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1

Electrochemical frequency modulation and inductively coupled plasma atomic emission spectroscopy methods for monitoring corrosion rates and inhibition of low alloy steel corrosion in HCl solutions and a test for validity of the Tafel extrapolation method  

International Nuclear Information System (INIS)

The inhibition effect of glycine (Gly) towards the corrosion of low alloy steel ASTM A213 grade T22 boiler steel was studied in aerated stagnant 0.50 M HCl solutions in the temperature range 20-60 deg. C using potentiodynamic polarization (Tafel polarization and linear polarization) and impedance techniques, complemented with scanning electron microscope (SEM) and energy dispersive X-ray (EDX). Electrochemical frequency modulation (EFM), a non-destructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, is also presented here. Experimental corrosion rates determined by the Tafel extrapolation method are compared with corrosion rates obtained by electrochemical, namely EFM technique, and chemical (i.e., non-electrochemical) method for steel in HCl. The chemical method of confirmation of the corrosion rates involved determination of the dissolved cation, using ICP-AES (inductively coupled plasma atomic emission spectrometry) method of analysis. Corrosion rates (in mm y-1) obtained from the electrochemical (Tafel extrapolation and EFM) and the chemical method, ICP, are in a good agreement. Polarization studies have shown that Gly is a good 'green', mixed-type inhibitor with cathodic predominance. The inhibition process was attributed to the formation of an adsorbed film on the metal surface that protects the metal against corrosive agents. Scanning electron microscopy (SEM) and energanning electron microscopy (SEM) and energy dispersion X-ray (EDX) examinations of the electrode surface confirmed the existence of such an adsorbed film. The inhibition efficiency increases with increase in Gly concentration, while it decreases with solution temperature. Temkin isotherm is successfully applied to describe the adsorption process. Thermodynamic functions for the adsorption process were determined.

2

? ? scattering by pole extrapolation methods  

International Nuclear Information System (INIS)

A 25-inch hydrogen bubble chamber was used at the Lawrence Berkeley Laboratory Bevatron to produce 300,000 pictures of ?+p interactions at an incident momentum of the ?+ of 2.67 GeV/c. The 2-prong events were processed using the FSD and the FOG-CLOUDY-FAIR data reduction system. Events of the nature ?+p ? ?+p?0 and ?+p ? ?+?+n with values of momentum transfer to the proton of -t less than or equal to 0.238 GeV2 were selected. These events were used to extrapolate to the pion pole (t = m/sub ?/2) in order to investigate the ? ? interaction with isospins of both T = 1 and T = 2. Two methods were used to do the extrapolation: the original Chew-Low method developed in 1959 and the Durr-Pilkuhn method developed in 1965 which takes into account centrifugal barrier penetration factors. At first it seemed that, while the Durr-Pilkuhn method gave better values for the total ? ? cross section, the Chew-Low method gave better values for the angular distribution. Further analysis, however, showed that if the requirement of total OPE (one-pion-exchange) were dropped, then the Durr-Pilkuhn method gave more reasonable values of the angular distribution as well as for the total ? ? cross section

3

An efficient method to evaluate energy variances for extrapolation methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The energy variance extrapolation method consists in relating the approximate energies in many-body calculations to the corresponding energy variances and inferring eigenvalues by extrapolating to zero variance. The method needs a fast evaluation of the energy variances. For many-body methods that expand the nuclear wave functions in terms of deformed Slater determinants, the best available method for the evaluation of energy variances scales with the sixth power of the numb...

Puddu, G.

2012-01-01

4

An efficient method to evaluate energy variances for extrapolation methods  

CERN Document Server

The energy variance extrapolation method consists in relating the approximate energies in many-body calculations to the corresponding energy variances and inferring eigenvalues by extrapolating to zero variance. The method needs a fast evaluation of the energy variances. For many-body methods that expand the nuclear wave functions in terms of deformed Slater determinants, the best available method for the evaluation of energy variances scales with the sixth power of the number of single-particle states. We propose a new method which depends on the number of single-particle orbits and the number of particles rather than the number of single-particle states. We discuss as an example the case of ${}^4He$ using the chiral N3LO interaction in a basis consisting up to 184 single-particle states.

Puddu, G

2012-01-01

5

Multiparameter extrapolation and deflation methods for solving equation systems  

Directory of Open Access Journals (Sweden)

Full Text Available Most models in economics and the applied sciences are solved by first order iterative techniques, usually those based on the Gauss-Seidel algorithm. This paper examines the convergence of multiparameter extrapolations (accelerations of first order iterations, as an improved approximation to the Newton method for solving arbitrary nonlinear equation systems. It generalises my earlier results on single parameter extrapolations. Richardson's generalised method and the deflation method for detecting successive solutions in nonlinear equation systems are also presented as multiparameter extrapolations of first order iterations. New convergence results are obtained for those methods.

A. J. Hughes Hallett

1984-12-01

6

Efficient extrapolation methods for electro- and magnetoquasistatic field simulations  

Directory of Open Access Journals (Sweden)

Full Text Available In magneto- and electroquasi-static time domain simulations with implicit time stepping schemes the iterative solvers applied to the large sparse (non-linear systems of equations are observed to converge faster if more accurate start solutions are available. Different extrapolation techniques for such new time step solutions are compared in combination with the preconditioned conjugate gradient algorithm. Simple extrapolation schemes based on Taylor series expansion are used as well as schemes derived especially for multi-stage implicit Runge-Kutta time stepping methods. With several initial guesses available, a new subspace projection extrapolation technique is proven to produce an optimal initial value vector. Numerical tests show the resulting improvements in terms of computational efficiency for several test problems. In quasistatischen elektromagnetischen Zeitbereichsimulationen mit impliziten Zeitschrittverfahren zeigt sich, dass die iterativen Lösungsverfahren für die großen dünnbesetzten (nicht-linearen Gleichungssysteme schneller konvergieren, wenn genauere Startlösungen vorgegeben werden. Verschiedene Extrapolationstechniken werden für jeweils neue Zeitschrittlösungen in Verbindung mit dem präkonditionierten Konjugierte Gradientenverfahren vorgestellt. Einfache Extrapolationsverfahren basierend auf Taylorreihenentwicklungen werden ebenso benutzt wie speziell für mehrstufige implizite Runge-Kutta-Verfahren entwickelte Verfahren. Sind verschiedene Startlösungen verfügbar, so erlaubt ein neues Unterraum-Projektion- Extrapolationsverfahren die Konstruktion eines optimalen neuen Startvektors. Numerische Tests zeigen die aus diesen Verfahren resultierenden Verbesserungen der numerischen Effizienz.

M. Clemens

2003-01-01

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The extrapolated successive overrelaxation (ESOR method for consistently ordered matrices  

Directory of Open Access Journals (Sweden)

Full Text Available This paper develops the theory of the Extrapolated Successive Overrelaxation (ESOR method as introduced by Sisler in [1], [2], [3] for the numerical solution of large sparse linear systems of the form Au=b, when A is a consistently ordered 2-cyclic matrix with non-vanishing diagonal elements and the Jacobi iteration matrix B possesses only real eigenvalues. The region of convergence for the ESOR method is described and the optimum values of the involved parameters are also determined. It is shown that if the minimum of the moduli of the eigenvalues of B, μ¯ does not vanish, then ESOR attains faster rate of convergence than SOR when 1−μ¯2<(1−μ¯212, where μ¯ denotes the spectral radius of B.

D. J. Evans

1984-06-01

8

MMOC- MODIFIED METHOD OF CHARACTERISTICS SONIC BOOM EXTRAPOLATION  

Science.gov (United States)

The Modified Method of Characteristics Sonic Boom Extrapolation program (MMOC) is a sonic boom propagation method which includes shock coalescence and incorporates the effects of asymmetry due to volume and lift. MMOC numerically integrates nonlinear equations from data at a finite distance from an airplane configuration at flight altitude to yield the sonic boom pressure signature at ground level. MMOC accounts for variations in entropy, enthalpy, and gravity for nonlinear effects near the aircraft, allowing extrapolation to begin nearer the body than in previous methods. This feature permits wind tunnel sonic boom models of up to three feet in length, enabling more detailed, realistic models than the previous six-inch sizes. It has been shown that elongated airplanes flying at high altitude and high Mach numbers can produce an acceptably low sonic boom. Shock coalescence in MMOC includes three-dimensional effects. The method is based on an axisymmetric solution with asymmetric effects determined by circumferential derivatives of the standard shock equations. Bow shocks and embedded shocks can be included in the near-field. The method of characteristics approach in MMOC allows large computational steps in the radial direction without loss of accuracy. MMOC is a propagation method rather than a predictive program. Thus input data (the flow field on a cylindrical surface at approximately one body length from the axis) must be supplied from calculations or experimental results. The MMOC package contains a uniform atmosphere pressure field program and interpolation routines for computing the required flow field data. Other user supplied input to MMOC includes Mach number, flow angles, and temperature. MMOC output tabulates locations of bow shocks and embedded shocks. When the calculations reach ground level, the overpressure and distance are printed, allowing the user to plot the pressure signature. MMOC is written in FORTRAN IV for batch execution and has been implemented on a CDC 170 series computer operating under NOS with a central memory requirement of approximately 223K of 60 bit words. This program was developed in 1983.

Darden, C. M.

1994-01-01

9

Extrapolation Method for System Reliability Assessment : A New Scheme  

DEFF Research Database (Denmark)

The present paper presents a new scheme for probability integral solution for system reliability analysis, which takes basis in the approaches by Naess et al. (2009) and Bucher (2009). The idea is to evaluate the probability integral by extrapolation, based on a sequence of MC approximations of integrals with scaled domains. The performance of this class of approximation depends on the approach applied for the scaling and the functional form utilized for the extrapolation. A scheme for this task is derived here taking basis in the theory of asymptotic solutions to multinormal probability integrals. The scheme is extended so that it can be applied to cases where the asymptotic property may not be valid and/or the random variables are not normally distributed. The performance of the scheme is investigated by four principal series and parallel systems and some practical examples. The results indicate that the proposed scheme is efficient and adds to generality for this class of approximations for probability integrals.

Nishijima, Kazuyoshi; Faber, Michael Havbro

2012-01-01

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The splitting extrapolation method a new technique in numerical solution of multidimensional problems  

CERN Document Server

The splitting extrapolation method is a newly developed technique for solving multidimensional mathematical problems. It overcomes the difficulties arising from Richardson's extrapolation when applied to these problems and obtains higher accuracy solutions with lower cost and a high degree of parallelism. The method is particularly suitable for solving large scale scientific and engineering problems.This book presents applications of the method to multidimensional integration, integral equations and partial differential equations. It also gives an introduction to combination methods which are

Tao, Lu

1995-01-01

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Nonlinear Force-free Extrapolation of the Coronal Magnetic Field Based on the Magnetohydrodynamic Relaxation Method  

Science.gov (United States)

We develop a nonlinear force-free field (NLFFF) extrapolation code based on the magnetohydrodynamic (MHD) relaxation method. We extend the classical MHD relaxation method in two important ways. First, we introduce an algorithm initially proposed by Dedner et al. to effectively clean the numerical errors associated with ? · B . Second, the multigrid type method is implemented in our NLFFF to perform direct analysis of the high-resolution magnetogram data. As a result of these two implementations, we successfully extrapolated the high resolution force-free field introduced by Low & Lou with better accuracy in a drastically shorter time. We also applied our extrapolation method to the MHD solution obtained from the flux-emergence simulation by Magara. We found that NLFFF extrapolation may be less effective for reproducing areas higher than a half-domain, where some magnetic loops are found in a state of continuous upward expansion. However, an inverse S-shaped structure consisting of the sheared and twisted loops formed in the lower region can be captured well through our NLFFF extrapolation method. We further discuss how well these sheared and twisted fields are reconstructed by estimating the magnetic topology and twist quantitatively.

Inoue, S.; Magara, T.; Pandey, V. S.; Shiota, D.; Kusano, K.; Choe, G. S.; Kim, K. S.

2014-01-01

12

Technique of Critical Current Density Measurement of Bulk Superconductor with Linear Extrapolation Method  

International Nuclear Information System (INIS)

Technique of critical current density measurement (Jc) of HTc bulk ceramic superconductor has been performed by using linear extrapolation with four-point probes method. The measurement of critical current density HTc bulk ceramic superconductor usually causes damage in contact resistance. In order to decrease this damage factor, we introduce extrapolation method. The extrapolating data show that the critical current density Jc for YBCO (123) and BSCCO (2212) at 77 K are 10,85(6) Amp.cm-2 and 14,46(6) Amp.cm-2, respectively. This technique is easier, simpler, and the use of the current flow is low, so it will not damage the contact resistance of the sample. We expect that the method can give a better solution for bulk superconductor application. Key words. : superconductor, critical temperature, and critical current density

13

Some practical applications of tracing and extrapolation methods in absolute standardization  

International Nuclear Information System (INIS)

The absolute standardization of solutions of 137Cs and of 144Ce + 144Pr was achieved by tracing and extrapolation methods. For 137Cs, a 134Cs standard solution was used as tracer. The overall uncertainties in the standardization of the two solutions were 1.5% and 1%, respectively. (author)

14

Nonlinear Force-Free Extrapolation of the Coronal Magnetic Field Based on the MHD Relaxation Method  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We develop a nonlinear force-free field (NLFFF) extrapolation code based on the magnetohydrodynamic (MHD) relaxation method. We extend the classical MHD relaxation method in two important ways. First, we introduce an algorithm initially proposed by cite{2002JCoPh.175..645D} to effectively clean the numerical errors associated with $nabla cdot vec{B}$. Second, the multi-grid type method is implemented in our NLFFF to perform direct analysis of the high-resolution magnetogram ...

Inoue, S.; Magara, T.; Pandey, V. S.; Shiota, D.; Kusano, K.; Choe, G. S.; Kim, K. S.

2013-01-01

15

A New Implementation of the Magnetohydrodynamics-Relaxation Method for Nonlinear Force-Free Field Extrapolation in the Solar Corona  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Magnetic field in the solar corona is usually extrapolated from photospheric vector magnetogram using a nonlinear force-free field (NLFFF) model. NLFFF extrapolation needs a considerable effort to be devoted for its numerical realization. In this paper we present a new implementation of the magnetohydrodynamics (MHD)-relaxation method for NLFFF extrapolation. The magneto-frictional approach which is introduced for speeding the relaxation of the MHD system is novelly realized...

Jiang, Chaowei; Feng, Xueshang

2012-01-01

16

Extrapolation of extreme sea levels: incorporation of Over-Threshold-Modeling to the Joint Probability Method  

Science.gov (United States)

In France, the storm Xynthia of February 27-28th, 2010 reminded engineers and stakeholders of the necessity for an accurate estimation of extreme sea levels for the risk assessment in coastal areas. Traditionally, two main approaches exist for the statistical extrapolation of extreme sea levels: the direct approach performs a direct extrapolation on the sea level data, while the indirect approach carries out a separate analysis of the deterministic component (astronomical tide) and stochastic component (meteorological residual, or surge). When the tidal component is large compared with the surge one, the latter approach is known to perform better. In this approach, the statistical extrapolation is performed on the surge component then the distribution of extreme seal levels is obtained by convolution of the tide and surge distributions. This model is often referred to as the Joint Probability Method. Different models from the univariate extreme theory have been applied in the past for extrapolating extreme surges, in particular the Annual Maxima Method (AMM) and the r-largest method. In this presentation, we apply the Peaks-Over-Threshold (POT) approach for declustering extreme surge events, coupled with the Poisson-GPD model for fitting extreme surge peaks. This methodology allows a sound estimation of both lower and upper tails of the stochastic distribution, including the estimation of the uncertainties associated to the fit by computing the confidence intervals. After convolution with the tide signal, the model yields the distribution for the whole range of possible sea level values. Particular attention is paid to the necessary distinction between sea level values observed at a regular time step, such as hourly, and sea level events, such as those occurring during a storm. Extremal indexes for both surges and levels are thus introduced. This methodology will be illustrated with a case study at Brest, France.

Mazas, Franck; Hamm, Luc; Kergadallan, Xavier

2013-04-01

17

Extrapolation methods for obtaining low-lying eigenvalues of a large-dimensional shell model Hamiltonian matrix  

International Nuclear Information System (INIS)

We propose some new, efficient, and practical extrapolation methods to obtain a few low-lying eigenenergies of a large-dimensional Hamiltonian matrix in the nuclear shell model. We obtain those energies at the desired accuracy by extrapolation after diagonalizing small-dimensional submatrices of the sorted Hamiltonian matrix.

18

The Impacts of Atmospheric Stability on the Accuracy of Wind Speed Extrapolation Methods  

Directory of Open Access Journals (Sweden)

Full Text Available The building of utility-scale wind farms requires knowledge of the wind speed climatology at hub height (typically 80–100 m. As most wind speed measurements are taken at 10 m above ground level, efforts are being made to relate 10-m measurements to approximate hub-height wind speeds. One common extrapolation method is the power law, which uses a shear parameter to estimate the wind shear between a reference height and hub height. The shear parameter is dependent on atmospheric stability and should ideally be determined independently for different atmospheric stability regimes. In this paper, data from the Oklahoma Mesonet are used to classify atmospheric stability and to develop stability-dependent power law fits for a nearby tall tower. Shear exponents developed from one month of data are applied to data from different seasons to determine the robustness of the power law method. In addition, similarity theory-based methods are investigated as possible alternatives to the power law. Results indicate that the power law method performs better than similarity theory methods, particularly under stable conditions, and can easily be applied to wind speed data from different seasons. In addition, the importance of using co-located near-surface and hub-height wind speed measurements to develop extrapolation fits is highlighted.

Jennifer F. Newman

2014-01-01

19

A method of creep rupture data extrapolation based on physical processes  

International Nuclear Information System (INIS)

There is a need for a reliable method to extrapolate generic creep rupture data to failure times in excess of the currently published times. A method based on well-understood and mathematically described physical processes is likely to be stable and reliable. Creep process descriptions have been developed based on accepted theory, to the extent that good fits with published data have been obtained. Methods have been developed to apply these descriptions to extrapolate creep rupture data to stresses below the published values. The relationship creep life parameter=f(ln(sinh(stress))) has been shown to be justifiable over the stress ranges of most interest, and gives realistic results at high temperatures and long times to failure. In the interests of continuity with past and present practice, the suggested method is intended to extend existing polynomial descriptions of life parameters at low stress. Where no polynomials exist, the method can be used to describe the behaviour of life parameters throughout the full range of a particular failure mode in the published data

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The Impacts of Atmospheric Stability on the Accuracy of Wind Speed Extrapolation Methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The building of utility-scale wind farms requires knowledge of the wind speed climatology at hub height (typically 80–100 m). As most wind speed measurements are taken at 10 m above ground level, efforts are being made to relate 10-m measurements to approximate hub-height wind speeds. One common extrapolation method is the power law, which uses a shear parameter to estimate the wind shear between a reference height and hub height. The shear parameter is dependent on atmospheric stability an...

Newman, Jennifer F.; Klein, Petra M.

2014-01-01

 
 
 
 
21

Low-cost extrapolation method for maximal lte radio base station exposure estimation: Test and validation  

International Nuclear Information System (INIS)

An experimental validation of a low-cost method for extrapolation and estimation of the maximal electromagnetic-field exposure from long-term evolution (LTE) radio base station installations are presented. No knowledge on down-link band occupation or service characteristics is required for the low-cost method. The method is applicable in situ. It only requires a basic spectrum analyser with appropriate field probes without the need of expensive dedicated LTE decoders. The method is validated both in laboratory and in situ, for a single-input single-output antenna LTE system and a 2x2 multiple-input multiple-output system, with low deviations in comparison with signals measured using dedicated LTE decoders. (authors)

22

Low-cost extrapolation method for maximal LTE radio base station exposure estimation: test and validation.  

Science.gov (United States)

An experimental validation of a low-cost method for extrapolation and estimation of the maximal electromagnetic-field exposure from long-term evolution (LTE) radio base station installations are presented. No knowledge on downlink band occupation or service characteristics is required for the low-cost method. The method is applicable in situ. It only requires a basic spectrum analyser with appropriate field probes without the need of expensive dedicated LTE decoders. The method is validated both in laboratory and in situ, for a single-input single-output antenna LTE system and a 2×2 multiple-input multiple-output system, with low deviations in comparison with signals measured using dedicated LTE decoders. PMID:23179190

Verloock, Leen; Joseph, Wout; Gati, Azeddine; Varsier, Nadège; Flach, Björn; Wiart, Joe; Martens, Luc

2013-06-01

23

An ADI extrapolated Crank-Nicolson orthogonal spline collocation method for nonlinear reaction-diffusion systems  

Science.gov (United States)

An alternating direction implicit (ADI) orthogonal spline collocation (OSC) method is described for the approximate solution of a class of nonlinear reaction-diffusion systems. Its efficacy is demonstrated on the solution of well-known examples of such systems, specifically the Brusselator, Gray-Scott, Gierer-Meinhardt and Schnakenberg models, and comparisons are made with other numerical techniques considered in the literature. The new ADI method is based on an extrapolated Crank-Nicolson OSC method and is algebraically linear. It is efficient, requiring at each time level only O(N) operations where N is the number of unknowns. Moreover, it is shown to produce approximations which are of optimal global accuracy in various norms, and to possess superconvergence properties.

Fernandes, Ryan I.; Fairweather, Graeme

2012-08-01

24

An extrapolation method for compressive strength prediction of hydraulic cement products  

Energy Technology Data Exchange (ETDEWEB)

The basis for the AMEBA Method is presented. A strength-time function is used to extrapolate the predicted cementitious material strength for a late (ALTA) age, based on two earlier age strengths--medium (MEDIA) and low (BAIXA) ages. The experimental basis for the method is data from the IPT-Brazil laboratory and the field, including a long-term study on concrete, research on limestone, slag, and fly-ash additions, and quality control data from a cement factory, a shotcrete tunnel lining, and a grout for structural repair. The method applicability was also verified for high-performance concrete with silica fume. The formula for predicting late age (e.g., 28 days) strength, for a given set of involved ages (e.g., 28,7, and 2 days) is normally a function only of the two earlier ages` (e.g., 7 and 2 days) strengths. This equation has been shown to be independent on materials variations, including cement brand, and is easy to use also graphically. Using the AMEBA method, and only needing to know the type of cement used, it has been possible to predict strengths satisfactorily, even without the preliminary tests which are required in other methods.

Siqueira Tango, C.E. de [IPT-Technological Research Inst., Sao Paulo (Brazil)

1998-07-01

25

Stepwise Global Error Control in an Explicit Runge-Kutta Method Using Local Extrapolation with High-Order Selective Quenching  

Directory of Open Access Journals (Sweden)

Full Text Available Stepwise local error control using local extrapolation in Runge-Kutta methods is well-known. In this paper, we introduce an algorithm, designated RK$rv$Q$z,$ that is capable of controlling local and global errors in a stepwise manner. The algorithm utilizes three Runge-Kutta methods, of orders $r,v$ and $z$, with $rextrapolation, whereas global error is controlled using a technique we have termed `quenching', which exploits the availability of a very high order solution and the use of a `safety factor', often present in local extrapolation methods. An example using RK34Q8 gives a clear indication of the effectiveness of the method.

Justin Steven Prentice

2011-05-01

26

Propagation of internal errors in explicit Runge–Kutta methods and internal stability of SSP and extrapolation methods  

In practical computation with Runge--Kutta methods, the stage equations are not satisfied exactly, due to roundoff errors, algebraic solver errors, and so forth. We show by example that propagation of such errors within a single step can have catastrophic effects for otherwise practical and well-known methods. We perform a general analysis of internal error propagation, emphasizing that it depends significantly on how the method is implemented. We show that for a fixed method, essentially any set of internal stability polynomials can be obtained by modifying the implementation details. We provide bounds on the internal error amplification constants for some classes of methods with many stages, including strong stability preserving methods and extrapolation methods. These results are used to prove error bounds in the presence of roundoff or other internal errors.

Ketcheson, David I.

2014-04-11

27

An investigation of the relationship between extrapolation parameters and approximate solutions in solving fuzzy linear systems using refinement of jacobi over relaxation method  

International Nuclear Information System (INIS)

Extrapolation parameters in Refinement of Jacobi over Relation method in solving fuzzy linear systems were hypothesized to influence the rate of convergence. This paper aims to investigate the relationship between extrapolation parameters and approximate solutions of fuzzy linear systems when solved using Refinement of Jacobi over Relaxation method. The Algorithms of Refinement of Jacobi over Relaxation method are proposed based on the Jacobi method that specifically used in solving the system. A five by five fuzzy linear system is given to investigate the convergence to exact solution with three different values of extrapolation parameters. The numerical results show that there is a positive correlation between extrapolation parameter and convergence to exact solution. The three extrapolation parameters suggest that convergence to exact solution can be increased in line with the increase in the values of extrapolation parameters.

28

Linear extrapolation distance for a black cylindrical control rod with the pulsed neutron method  

International Nuclear Information System (INIS)

The objective of this experiment was to measure the linear extrapolation distance for a central black cylindrical control rod in a cylindrical water moderator. The radius for both the control rod and the moderator was varied. The pulsed neutron technique was used and the decay constant was measured for both a homogeneous and a heterogeneous system. From the difference in the decay constants the extrapolation distance could be calculated. The conclusion is that within experimental error it is safe to use the approximate formula given by Pellaud or the more exact one given by Kavenoky. We can also conclude that linear anisotropic scattering is accounted for in a correct way in the approximate formula given by Pellaud and Prinja and Williams

29

Principal components analysis and polynomials as methods for the track extrapolation/interpolation for SAPHIR  

International Nuclear Information System (INIS)

A program to investigate the possibility of track extrapolation and interpolation for drift chambers with the Principal Components Analysis and polynoms was written for SAPHIR. The results for the most significant configurations at SAPHIR were pointed out. It was shown that the Principal Components Analysis is a good basis to write a fast track reconstruction program for a drift chamber using a global track model in an inhomogeneous magnetic field. A data input/output package was written, too. (orig.)

30

Comparison of extrapolation methods for creep rupture stresses of 12Cr and 18Cr10NiTi steels  

International Nuclear Information System (INIS)

As a part of a Soviet-Swedish research programme the creep rupture properties of two heat resisting steels namely a 12% Cr steel and an 18% Cr12% Ni titanium stabilized steel have been studied. One heat from each country of both steels were creep tested. The strength of the 12% Cr steels was similar to earlier reported strength values, the Soviet steel being some-what stronger due to a higher tungsten content. The strength of the Swedish 18/12 Ti steel agreed with earlier results, while the properties of the Soviet steel were inferior to those reported from earlier Soviet creep testings. Three extrapolation methods were compared on creep rupture data collected in both countries. Isothermal extrapolation and an algebraic method of Soviet origin gave in many cases rather similar results, while the parameter method recommended by ISO resulted in higher rupture strength values at longer times. (author)

31

A comparison of high-order explicit Runge–Kutta, extrapolation, and deferred correction methods in serial and parallel  

We compare the three main types of high-order one-step initial value solvers: extrapolation, spectral deferred correction, and embedded Runge–Kutta pairs. We consider orders four through twelve, including both serial and parallel implementations. We cast extrapolation and deferred correction methods as fixed-order Runge–Kutta methods, providing a natural framework for the comparison. The stability and accuracy properties of the methods are analyzed by theoretical measures, and these are compared with the results of numerical tests. In serial, the eighth-order pair of Prince and Dormand (DOP8) is most efficient. But other high-order methods can be more efficient than DOP8 when implemented in parallel. This is demonstrated by comparing a parallelized version of the wellknown ODEX code with the (serial) DOP853 code. For an N-body problem with N = 400, the experimental extrapolation code is as fast as the tuned Runge–Kutta pair at loose tolerances, and is up to two times as fast at tight tolerances.

Ketcheson, David I.

2014-06-13

32

Accurate ab initio potential of CO(X1?+) at low cost via correlation scaling and extrapolation method  

International Nuclear Information System (INIS)

The potential energy curve (PEC) for the ground state of CO(X1?+) has been investigated by the highly accurate valence internally contracted multi-reference configuration interaction with the Davidson correction (MRCI+Q) method in combination with a series of correlation-consistent basis sets of Dunning and co-workers. The scheme proposed by Varandas, which enables high-quality molecular potentials to be obtained from small basis set calculations via scaling and extrapolation of the electron correlation to the complete basis set limit plus extrapolation to the complete basis set limit of the complete-active-space self-consistent field energy, has been applied to the system under consideration here. The present results are compared with the other theoretical and experimental data, and show that the present methods are credible and accurate.

33

Preprocessing the Photospheric Vector Magnetograms for an NLFFF Extrapolation Using a Potential-Field Model and an Optimization Method  

Science.gov (United States)

Numerical reconstruction/extrapolation of the coronal nonlinear force-free magnetic field (NLFFF) usually takes the photospheric vector magnetogram as input at the bottom boundary. The magnetic field observed at the photosphere, however, contains a force that is in conflict with the fundamental assumption of the force-free model. It also contains measurement noise, which hinders the practical computation. Wiegelmann, Inhester, and Sakurai ( Solar Phys. 233, 215, 2006) have proposed to preprocess the raw magnetogram to remove the force and noise to provide better input for NLFFF modeling. In this paper we develop a new code of magnetogram preprocessing that is consistent with our extrapolation method CESE-MHD-NLFFF (Jiang, Feng, and Xiang in Astrophys. J. 755, 62, 2012; Jiang and Feng in Astrophys. J. 749, 135, 2012a). Based on the magnetic-splitting rule that a magnetic field can be split into a potential-field part and a non-potential part, we split the magnetogram and dealt with the two parts separately. The preprocessing of the magnetogram's potential part is based on a numerical potential-field model, and the non-potential part is preprocessed using the similar optimization method of Wiegelmann, Inhester, and Sakurai (2006). The code was applied to the SDO/HMI data, and results show that the method can remove the force and noise efficiently and improve the extrapolation quality.

Jiang, Chaowei; Feng, Xueshang

2014-01-01

34

Comparison among creep rupture strength extrapolation methods with application to data for AISI 316 SS from Italy, France, U.K. and F.R.G  

International Nuclear Information System (INIS)

Inside Activity 3 ''Materials'' of WGCS, the member states UK and FRG have developed a work regarding extrapolation methods for creep data. This work has been done by comparising extrapolation methods in use in their countries by applying them to creep rupture strength data on AISI 316 SS obtained in UK and FRG. This work has been issued on April 1978 and the Community has dealed it to all Activity 3 Members. Italy, in the figure of NIRA S.p.A., has received, from the European Community a contract to extend the work to Italian and French data, using extrapolation methods currently in use in Italy. The work should deal with the following points: - Collect of Italian experimental data; - Chemical analysis on Italian Specimen; - Comparison among Italian experimental data with French, FRG and UK data; - Description of extrapolation methods in use in Italy; - Application of these extrapolation methods to Italian, French, British and Germany data; - Extensions of a Final Report

35

Improvement of flux distribution calculation using the extrapolation method of Richardson  

International Nuclear Information System (INIS)

Richardson have advanced a method for increasing the accuracy in numerical solving of linear differential equations. So, he proposed several schemes for performing algorythms, in which various approximtion parameters are used. It has been proved that a linear combination of this solution under certain circumstances gives a higher accuracy. Starting from these facts the present paper descpibes the application of the Richardson's method in improving the neutron flux calculation by using the EXTERMINATOR-2-INPR code. The considered benchmark problem has been conceived by D.R.Vondy from ORNL-USA. It consists of solving the multigroup diffusion equations for homogeneous two-dimensional slab. The results obtained show the efficiency of the Richardson method in improving the neutron flux calculation and constitutes a basis for achieving algorythms for other categories of problems. (authors)

36

An approach to estimating and extrapolating model error based on inverse problem methods: towards accurate numerical weather prediction  

Science.gov (United States)

Model error is one of the key factors restricting the accuracy of numerical weather prediction (NWP). Considering the continuous evolution of the atmosphere, the observed data (ignoring the measurement error) can be viewed as a series of solutions of an accurate model governing the actual atmosphere. Model error is represented as an unknown term in the accurate model, thus NWP can be considered as an inverse problem to uncover the unknown error term. The inverse problem models can absorb long periods of observed data to generate model error correction procedures. They thus resolve the deficiency and faultiness of the NWP schemes employing only the initial-time data. In this study we construct two inverse problem models to estimate and extrapolate the time-varying and spatial-varying model errors in both the historical and forecast periods by using recent observations and analogue phenomena of the atmosphere. Numerical experiment on Burgers' equation has illustrated the substantial forecast improvement using inverse problem algorithms. The proposed inverse problem methods of suppressing NWP errors will be useful in future high accuracy applications of NWP.

Hu, Shu-Juan; Qiu, Chun-Yu; Zhang, Li-Yun; Huang, Qi-Can; Yu, Hai-Peng; Chou, Ji-Fan

2014-08-01

37

Life of the Tafel equation: Current understanding and prospects for the second century  

International Nuclear Information System (INIS)

The life of Tafel equation is considered briefly as evolution in the understanding of Tafel's empiric parameters in the framework of various phenomenological and theoretical approaches. Modern theories of the interfacial charge transfer reactions are employed to explain the behavior of transfer coefficient versus electrode overvoltage and deviations of this quantity from 0.5 at low overvoltage. The effects of intramolecular reorganization, orbital overlap, reactant quantum modes and solvent dynamics are addressed and illustrated by model calculations. An attempt is made to propose new explanations of some data reported in the literature

38

A review of creep-fatigue life prediction methods: Identification and extrapolation to long term and low strain cyclic loading  

International Nuclear Information System (INIS)

Eight creep-fatigue interaction models are identified on a set of LCF experimental data. The material is 316 L type stainless steel, the temperature is 6000C. The general agreement between tests and predictions is good in the experimental range. Tentative extrapolations are made towards low strain and along dwell. Opposite trends are then pointed out on stress dependent and strain range dependent models. The final results are still encouraging and general rules are given concerning the long term life prediction. (orig.)

39

Interpolation and extrapolation method to analyze irradiation-induced dimensional change data of graphite for design of core components in very high temperature reactor (VHTR)  

International Nuclear Information System (INIS)

Graphite materials are used as core components in the High-Temperature Gas-Cooled Reactor (HTGR) and Very High Temperature Reactor (VHTR). The authors prepared technical documents for design, material, products, in-service inspection and maintenance of the graphite components for the HTGR/VHTR, which were summarized as a draft of standard for the graphite components through discussion made in a 'Special committee on research on preparation for codes for graphite components in HTGR' set up within AESJ. The draft of standard contains graphical expressions for the irradiated material properties of IG-110 graphite. It is possible to use the graphical expressions for the components design of VHTR. The graphs were obtained based on the interpolation and extrapolation of the irradiation data. The irradiation-induced dimensional change of IG-110 graphite was obtained through the interpolation and extrapolation of the irradiation data with a quadratic equation of fast neutron fluence. The irradiation data for H-451 and ATR-2E graphites were used for the evaluation of the interpolation and extrapolation of irradiation data for IG-110. It was shown in this study that the proposed interpolation and extrapolation method is reasonable for IG-110 with regard to the database available at present. (author)

40

Impedance and Tafel-plot techniques of indium in acidic media  

International Nuclear Information System (INIS)

The corrosion and electrochemical behaviour of indium in various concentrations of hydrochloric and sulphuric acids have been studied using impedance and Tafel-plot measurements over cathodic and anodic regions. Numerical values of polarisation resistances, double layer capacitances, corrosion potentials and corrosion currents are calculated, compared and discussed. (author). 15 refs., 6 figs., 2 tabs

 
 
 
 
41

Infrared extrapolations for atomic nuclei  

CERN Document Server

Harmonic oscillator model-space truncations introduce systematic errors to the calculation of binding energies and other observables. We identify the relevant infrared scaling variable and give values for this nucleus-dependent quantity. We consider isotopes of oxygen computed with the coupled-cluster method from chiral nucleon-nucleon interactions at next-to-next-to-leading order and show that the infrared component of the error is sufficiently understood to permit controlled extrapolations. By employing oscillator spaces with relatively large frequencies, well above the energy minimum, the ultraviolet corrections can be suppressed while infrared extrapolations over tens of MeVs are accurate for ground-state energies. However, robust uncertainty quantification for extrapolated quantities that fully accounts for systematic errors is not yet developed.

Furnstahl, R J; Papenbrock, T; Wendt, K A

2014-01-01

42

The nanostructure and microstructure of steels: Electrochemical Tafel behaviour and atomic force microscopy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The influence of chemical composition and heat treatment on a low-carbon steel, chromium steel and high speed steel has been examined by polarisation curves and electrochemical parameters deduced from the Tafel plots. The electrochemical corrosion resistance, which is small between the as-received steels become greater after heat treatment, following the order: carbon steel < chromium steel ~ high speed steel. To explain these differences, the nano- and microstructure of the steel...

Alves, Vale?ria A.; Paquim, Ana M. Chiorcea; Cavaleiro, Albano; Brett, Christopher M. A.

2005-01-01

43

Principles of animal extrapolation  

Energy Technology Data Exchange (ETDEWEB)

Animal Extrapolation presents a comprehensive examination of the scientific issues involved in extrapolating results of animal experiments to human response. This text attempts to present a comprehensive synthesis and analysis of the host of biomedical and toxicological studies of interspecies extrapolation. Calabrese's work presents not only the conceptual basis of interspecies extrapolation, but also illustrates how these principles may be better used in selection of animal experimentation models and in the interpretation of animal experimental results. The book's theme centers around four types of extrapolation: (1) from average animal model to the average human; (2) from small animals to large ones; (3) from high-risk animal to the high risk human; and (4) from high doses of exposure to lower, more realistic, doses. Calabrese attacks the issues of interspecies extrapolation by dealing individually with the factors which contribute to interspecies variability: differences in absorption, intestinal flora, tissue distribution, metabolism, repair mechanisms, and excretion. From this foundation, Calabrese then discusses the heterogeneticity of these same factors in the human population in an attempt to evaluate the representativeness of various animal models in light of interindividual variations. In addition to discussing the question of suitable animal models for specific high-risk groups and specific toxicological endpoints, the author also examines extrapolation questions related to the use of short-term tests to predict long-term human carcinogenicity and birth defects. The book is comprehensive in scope and specific in detail; for those environmental health professions seeking to understand the toxicological models which underlay health risk assessments, Animal Extrapolation is a valuable information source.

Calabrese, E.J.

1991-01-01

44

A Fourier method and an extrapolation technique for Stokes' first problem for a heated generalized second grade fluid with fractional derivative  

Science.gov (United States)

In this article, we consider Stokes' first problem for a heated generalized second grade fluid with fractional derivative (SFP-HGSGF). Implicit and explicit numerical approximation schemes for the SFP-HGSGF are presented. The stability and convergence of the numerical schemes are discussed using a Fourier method. In addition, the solvability of the implicit numerical approximation scheme is also analyzed. A Richardson extrapolation technique for improving the order of convergence of the implicit scheme is proposed. Finally, a numerical test is given. The numerical results demonstrate the good performance of our theoretical analysis.

Chen, Chang-Ming; Liu, F.; Anh, V.

2009-01-01

45

Loomemajandus - Eesti loojad on valmis, Eesti tööstus veel mitte / Erik Terk, Külliki Tafel-Viia, Silja Lassur ; intervjueerinud Mikk Salu  

Index Scriptorium Estoniae

Eestis korraldatud uuringu "Eesti loomemajanduse potentsiaal ja arenguks vajalikud riikud toetusmeetmed" tulemustest lähtudes püütakse leida optimaalseid suhteid loovinimeste toetusmeetmete ja iseorganiseerumise vahel. Vestlusringis Eesti Tuleviku-uuringute Instituudi direktor Erik Terk ja teadurid Silja Lassur ja Külliki Tafel-Viia

Terk, Erik, 1952-

2009-01-01

46

Finite lattice extrapolation algorithms  

International Nuclear Information System (INIS)

Two algorithms for sequence extrapolation, due to von den Broeck and Schwartz and Bulirsch and Stoer are reviewed and critically compared. Applications to three states and six states quantum chains and to the (2+1)D Ising model show that the algorithm of Bulirsch and Stoer is superior, in particular if only very few finite lattice data are available. (orig.)

47

The nanostructure and microstructure of steels: Electrochemical Tafel behaviour and atomic force microscopy  

International Nuclear Information System (INIS)

The influence of chemical composition and heat treatment on a low-carbon steel, chromium steel and high speed steel has been examined by polarisation curves and electrochemical parameters deduced from the Tafel plots. The electrochemical corrosion resistance, which is small between the as-received steels become greater after heat treatment, following the order: carbon steel 3 in ethanol). This causes preferential attack of the ferrite phases showing the carbide phases more clearly. From these nanostructural studies it was possible to better understand why the passive films formed on chromium steel and high speed steel have superior protective properties to those formed on carbon steel

48

Extrapolating future Arctic ozone losses  

Directory of Open Access Journals (Sweden)

Full Text Available Future increases in the concentration of greenhouse gases and water vapour may cool the stratosphere further and increase the amount of polar stratospheric clouds (PSCs. Future Arctic PSC areas have been extrapolated from the highly significant trends 1958-2001. Using a tight correlation between PSC area and the total vortex ozone depletion and taking the decreasing amounts of ozone depleting substances into account we make empirical estimates of future ozone. The result is that Arctic ozone losses increase until 2010-2015 and decrease only slightly afterwards. However, for such a long extrapolation into the future caution is necessary. Tentatively taking the modelled decrease in the ozone trend in the future into account results in almost constant ozone depletions until 2020 and slight decreases afterwards. This approach is a complementary method of prediction to that based on the complex coupled chemistry-climate models (CCMs.

B. M. Knudsen

2004-01-01

49

Ecotoxicological effects extrapolation models  

Energy Technology Data Exchange (ETDEWEB)

One of the central problems of ecological risk assessment is modeling the relationship between test endpoints (numerical summaries of the results of toxicity tests) and assessment endpoints (formal expressions of the properties of the environment that are to be protected). For example, one may wish to estimate the reduction in species richness of fishes in a stream reach exposed to an effluent and have only a fathead minnow 96 hr LC50 as an effects metric. The problem is to extrapolate from what is known (the fathead minnow LC50) to what matters to the decision maker, the loss of fish species. Models used for this purpose may be termed Effects Extrapolation Models (EEMs) or Activity-Activity Relationships (AARs), by analogy to Structure-Activity Relationships (SARs). These models have been previously reviewed in Ch. 7 and 9 of and by an OECD workshop. This paper updates those reviews and attempts to further clarify the issues involved in the development and use of EEMs. Although there is some overlap, this paper does not repeat those reviews and the reader is referred to the previous reviews for a more complete historical perspective, and for treatment of additional extrapolation issues.

Suter, G.W. II

1996-09-01

50

A fast marching approach to multidimensional extrapolation  

Science.gov (United States)

A computationally efficient approach to extrapolating a data field with second order accuracy is presented. This is achieved through the sequential solution of non-homogeneous linear static Hamilton-Jacobi equations, which can be performed rapidly using the fast marching methodology. In particular, the method relies on a fast marching calculation of the distance from the manifold ? that separates the subdomain ?in over which the quanity is known from the subdomain ?out over which the quantity is to be extrapolated. A parallel algorithm is included and discussed in the appendices. Results are compared to the multidimensional partial differential equation (PDE) extrapolation approach of Aslam (Aslam (2004) [31]). It is shown that the rate of convergence of the extrapolation within a narrow band near ? is controlled by both the number of successive extrapolations performed and the order of accuracy of the spatial discretization. For m successive extrapolating steps and a spatial discretization scheme of order N, the rate of convergence in a narrow band is shown to be min(N+1,m+1). Results show that for a wide range of error levels, the fast marching extrapolation strategy leads to dramatic improvements in computational cost when compared to the PDE approach.

McCaslin, Jeremy O.; Courtine, Émilien; Desjardins, Olivier

2014-10-01

51

Load Extrapolation During Operation for Wind Turbines  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the recent years load extrapolation for wind turbines has been widely considered in the wind turbine industry. Loads on wind turbines during operations are normally dependent on the mean wind speed, the turbulence intensity and the type and settings of the control system. All these parameters must be taken into account when characteristic load effects during operation are determined. In the wind turbine standard IEC 61400-1 a method for load extrapolation using the peak over threshold meth...

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

2008-01-01

52

Experimental check of the use of unconventional reference materials for EDS analysis in a TEM by extrapolation method based on pure elements  

Science.gov (United States)

In this work, the use of unconventional reference materials to determine experimentally the Cliff-Lorimer factor for EDS quantitative analysis with a TEM is checked by means of an alternative experimental procedure. The k-factor is determined by the extrapolation method based on pure elements, by measuring the normalized X-ray intensities emitted by thin films of pure gold and pure silver of different thickness, accurately measured by X-ray reflectivity. The goal of this work is to confirm the value of the k-factor previously obtained by the use of unconventional reference materials consisting of a bi-layer of pure gold on pure silver. The current result is in accordance with the previous one when considering their error bars, however, their relative difference is about 13 %, probably due to some uncertainties in mass thickness measurements. The mass thickness measurement of the layers of pure elements needs to be performed by different methods in order to reduce its uncertainty.

Nacucchi, M.; Alvisi, M.; Altamura, D.; Pfister, V.; Valerini, D.; Mello, D.; Giannini, C.

2012-03-01

53

Gauging station rating curve extrapolation using HEC-RAS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Rating curve represents stage-discharge relationship and is used to transform observed water level into discharge. At high water levels, the stage-discharge relationship often has to be extrapolated due to lack of measured data. The graduation thesis analyses rating curve extrapolation for gauging station Litija on river Sava. The intent of thesis is to narrow the expansion area of extrapolation. There are different methods for extrapolating stage-discharge relationships and most advanced of ...

S?upek, Miha

2008-01-01

54

Ground-state inversion method applied to calculation of molecular photoionization cross-sections by atomic extrapolation: Interference effects at low energies  

International Nuclear Information System (INIS)

The ground-state inversion method, which we have previously developed for the calculation of atomic cross-sections, is applied to the calculation of molecular photoionization cross-sections. These are obtained as a weighted sum of atomic subshell cross-sections plus multi-centre interference terms. The atomic cross-sections are calculated directly for the atomic functions which when summed over centre and symmetry yield the molecular orbital wave function. The use of the ground-state inversion method for this allows the effect of the molecular environment on the atomic cross-sections to be calculated. Multi-centre terms are estimated on the basis of an effective plane-wave expression for this contribution to the total cross-section. Finally the method is applied to the range of photon energies from 0 to 44 eV where atomic extrapolation procedures have not previously been tested. Results obtained for H2, N2 and CO show good agreement with experiment, particularly when interference effects and effects of the molecular environment on the atomic cross-sections are included. The accuracy is very much better than that of previous plane-wave and orthogonalized plane-wave methods, and can stand comparison with that of recent more sophisticated approaches. It is a feature of the method that calculation of cross-sections either of atoms or of large molecules requires very little computer time, provided that good quality wave functions are available, and itality wave functions are available, and it is then of considerable potential practical interest for photoelectorn spectroscopy. (orig.)

55

Quantitation from Tafel analysis in solid-state voltammetry. Application to the study of cobalt and copper pigments in severely damaged frescoes.  

Science.gov (United States)

A novel method, using Tafel plots, for quantifying electroactive species in solid materials when their voltammetric signals are strongly overlapped is described. This is applied to the analysis of submicrosamples from the highly damaged frescoes painted by Palomino (1707) in the ceiling vault of the Sant Joan del Mercat church in Valencia, Spain. These paintings, which were fired in 1936, contained cobalt smalt plus azurite mixtures, this last being altered to tenorite (CuO). The reported method provides a quantitation of the cobalt smalt/azurite, tenorite/(azurite + smalt) relationships in samples, thus providing direct information on pigment dosage (smalt/azurite ratio) in pristine paintings, extent of alteration, and temperature experienced by the frescoes during the gunfire episode. Distinction between Palomino paintings and other painters was clearly obtained due to the presence of malachite in these last. PMID:18324838

Doménech, Antonio; Doménech-Carbó, María Teresa; Edwards, Howell G M

2008-04-15

56

Extrapolation Distances for Pulsed Neutron Experiments  

International Nuclear Information System (INIS)

Attention has been drawn in earlier work to the effect of uncertainty in extrapolation distance on the results of pulsed neutron experiments and hence to the need for more accurate knowledge of this parameter. The extrapolated endpoints can be obtained from flux plots and the value for large systems can be deduced from diffusion coefficients. Information from both approaches is given and the dependence of extrapolated endpoint on temperature and on buckling is discussed. Decay times and time-dependent flux plots have been measured in pulsed source experiments on small, accurately-known, volumes of water and Dowtherm A (thermex) by the use of a small scintillation detector and a time analyser; a separate scintillation detector or a BF3 counter has been used as a monitor. Spatial harmonic analysis of the flux plots was performed by the method of least squares to obtain the extrapolated endpoints once appropriate corrections have been made to the recorded counts. Some consideration was given to the possibility of testing for the effect of flux distortion near the boundary by successive removal of the outer points and to the effects on extrapolated endpoint of the flux perturbation produced by the detector. The results presented are mainly for measurements at 20°C in 4-in and 7-in cubic containers lined with cadmium, but very preliminary information was obtained for water at temperatures up to 80°C and equipment is being designed to extend the range of temperatures still further. (author)

57

Elementary calculation of the extrapolation  

International Nuclear Information System (INIS)

A simple projectional technique combined with an equally simple parametric representation of the transient part of the neutron total flux is proposed for an elementary straightforward calculation of the extrapolation distance in diffusing media. (author)

58

Uncertainties of Euclidean Time Extrapolation in Lattice Effective Field Theory  

CERN Document Server

Extrapolations in Euclidean time form a central part of Nuclear Lattice Effective Field Theory (NLEFT) calculations using the Projection Monte Carlo method, as the sign problem in many cases prevents simulations at large Euclidean time. We review the next-to-next-to-leading order NLEFT results for the alpha nuclei up to $^{28}$Si, with emphasis on the Euclidean time extrapolations, their expected accuracy and potential pitfalls. We also discuss possible avenues for improving the reliability of Euclidean time extrapolations in NLEFT.

Lähde, Timo A; Krebs, Hermann; Lee, Dean; Meißner, Ulf-G; Rupak, Gautam

2014-01-01

59

One-way Wavefield Extrapolation in Riemannian Coordinates  

Science.gov (United States)

Images of crustal and lithospheric-scale structure can be created through seismic wavefield extrapolation, which extends surface-recorded data to depth through application of a wave-equation operator. The one-way extrapolation operators are derived from the acoustic wave-equation dispersion relation, and are usually defined in a Cartesian coordinate system with a vertical extrapolation axis. However, in this formulation there is an assumption that a vertical extrapolation axis can handle all wavefield propagation effects. In particular, there are numerous seismic imaging experiments where challenges such as incorporating rough topography, modeling overturning waves, and accounting for spherical Earth effects make extrapolation in Cartesian coordinates impractical. Riemannian wavefield extrapolation (RWE) (Sava and Fomel, 2004) is a generalization of the downward continuation concept to coordinate systems that incorporate geometrical or wave propagation effects. For example, geometrical effects such as topography can be directly incorporated into the coordinate system, and wavefield extrapolation commenced directly from relief (Shragge and Sava, AGU 2004). Another example is modeling path propagation effects directly in the coordinate system enabling accurate one-way wavefield extrapolation, even in situations where wavefields overturn. The method is implemented with a mixed domain solution involving both Fourier and space-domain finite differences. The algorithm is modestly more costly than wavefield extrapolation performed on a Cartesian computational mesh.

Sava, P. C.; Shragge, J. C.; Fomel, S. B.

2004-12-01

60

Effective orthorhombic anisotropic models for wavefield extrapolation  

Science.gov (United States)

Wavefield extrapolation in orthorhombic anisotropic media incorporates complicated but realistic models to reproduce wave propagation phenomena in the Earth's subsurface. Compared with the representations used for simpler symmetries, such as transversely isotropic or isotropic, orthorhombic models require an extended and more elaborated formulation that also involves more expensive computational processes. The acoustic assumption yields more efficient description of the orthorhombic wave equation that also provides a simplified representation for the orthorhombic dispersion relation. However, such representation is hampered by the sixth-order nature of the acoustic wave equation, as it also encompasses the contribution of shear waves. To reduce the computational cost of wavefield extrapolation in such media, we generate effective isotropic inhomogeneous models that are capable of reproducing the first-arrival kinematic aspects of the orthorhombic wavefield. First, in order to compute traveltimes in vertical orthorhombic media, we develop a stable, efficient and accurate algorithm based on the fast marching method. The derived orthorhombic acoustic dispersion relation, unlike the isotropic or transversely isotropic ones, is represented by a sixth order polynomial equation with the fastest solution corresponding to outgoing P waves in acoustic media. The effective velocity models are then computed by evaluating the traveltime gradients of the orthorhombic traveltime solution, and using them to explicitly evaluate the corresponding inhomogeneous isotropic velocity field. The inverted effective velocity fields are source dependent and produce equivalent first-arrival kinematic descriptions of wave propagation in orthorhombic media. We extrapolate wavefields in these isotropic effective velocity models using the more efficient isotropic operator, and the results compare well, especially kinematically, with those obtained from the more expensive anisotropic extrapolator.

Ibanez-Jacome, Wilson; Alkhalifah, Tariq; Waheed, Umair bin

2014-09-01

 
 
 
 
61

Extrapolation of Incomplete Image Data with Discrete Orthogonal Transforms  

Directory of Open Access Journals (Sweden)

Full Text Available In image processing and transmission, interpolation andextrapolation are of great importance whenever missing pixels have tobe filled in, and many methods have been proposed to solve thisproblem. In this paper we present a method for extrapolating themissing data with an existing set of basis functions of a selectedorthogonal transform. The best extrapolation is found according tolinear approximation theory as a weighted sum of basis functions, wherecoefficients of the sum are solutions of the derived matrix equation.

J. Polec

2004-12-01

62

In vitro-in vivo extrapolation of quantitative hepatic biotransformation data for fish - I. A review of methods, and strategies for incorporating intrinsic clearance estimates into chemical kinetic models  

Energy Technology Data Exchange (ETDEWEB)

Mammalian researchers have developed a stepwise approach to predict in vivo hepatic clearance from measurements of in vitro hepatic metabolism. The resulting clearance estimates have been used to screen drug candidates, identify potential drug-drug interactions, investigate idiosyncratic drug responses, and support toxicology risk assessments. In this report we review these methods, discuss their potential application to studies with fish, and describe how extrapolated values could be incorporated into well-known compartmental kinetic models. Empirical equations that relate extrapolation factors to chemical log Kow are given to facilitate the incorporation of metabolism data into bioconcentration and bioaccumulation models. Because they explicitly incorporate the concept of clearance, compartmental clearance volume models are particularly well suited for incorporating hepatic clearance estimates. The manner in which these clearance values are incorporated into a given model depends, however, on the measurement frame of reference. Procedures for the incorporation of in vitro metabolism data into physiologically based toxicokinetic (PBTK) models are also described. Unlike most compartmental models, PBTK models are developed to describe the effects of metabolism in the tissue where it occurs. In addition, PBTK models are well suited to modeling metabolism in more than one tissue.

Nichols, John W.; Schultz, Irv R.; Fitzsimmons, Patrick N..

2006-06-10

63

Extrapolations of nuclear binding energies from new linear mass relations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a method to extrapolate nuclear binding energies from known values for neighbouring nuclei. We select four specific mass relations constructed to eliminate smooth variation of the binding energy as function nucleon numbers. The fast odd-even variations are avoided by comparing nuclei with same parity. The mass relations are first tested and shown to either be rather accurately obeyed or revealing signatures of quickly varying structures. Extrapolations are initial...

Hove, D.; Jensen, A. S.; Riisager, K.

2014-01-01

64

Application of Curve Fitting Extrapolation in Measuring Transient Surface Temperature  

Directory of Open Access Journals (Sweden)

Full Text Available The engine inner wall surface temperature was measured by the plug blind-hole extrapolation, and multiple thermocouples were installed at different depths in the substrate. The engine wall extrapolation model of transient high temperature was established according to the basic principles of heat transfer. The transient temperatures were measured by thermocouples buried at different depths of the engine wall and fitting curve was got. The transient temperature field which was generated by the three oxy-hydrogen flame guns was used to simulate the transient high temperature field inside the engine wall. The simulated inner wall surface temperature curves of the engine could be got by the curve fitting extrapolation of temperature sensor and the infrared thermometer respectively, which show good agreement in the overall trend and at the peak point, and verify the correctness of the extrapolation model and method.

Xiaojian Hao

2013-08-01

65

The Magnetic Field of Active Region 11158 During the 2011 February 12-17 Flares : Differences between Photospheric Extrapolation and Coronal Forward-Fitting Methods  

CERN Document Server

We developed a {\\sl coronal non-linear force-free field (COR-NLFFF)} forward-fitting code that fits an approximate {\\sl non-linear force-free field (NLFFF)} solution to the observed geometry of automatically traced coronal loops. In contrast to photospheric NLFFF codes, which calculate a magnetic field solution from the constraints of the transverse photospheric field, this new code uses coronal constraints instead, and this way provides important information on systematic errors of each magnetic field calculation method, as well as on the non-forcefreeness in the lower chromosphere. In this study we applied the COR-NLFFF code to active region NOAA 11158, during the time interval of 2011 Feb 12 to 17, which includes an X2.2 GOES-class flare plus 35 M and C-class flares. We calcuated the free magnetic energy with a 6-minute cadence over 5 days. We find good agreement between the two types of codes for the total nonpotential $E_N$ and potential energy $E_P$, but find up to a factor of 4 discrepancy in the free ...

Aschwanden, Markus J; Liu, Yang

2014-01-01

66

Efficient depth extrapolation of waves in elastic isotropic media  

CERN Document Server

We propose a computationally efficient technique for extrapolating seismic waves in an arbitrary isotropic elastic medium. The method is based on factorizing the full elastic wave equation into a product of pseudo-differential operators. The method extrapolates displacement fields, hence can be used for modeling both pressure and shear waves. The proposed method can achieve a significant reduction in the cost of elastic modeling compared to the currently prevalent time- and frequency-domain numeric modeling methods and can contribute to making multicomponent elastic modeling part of the standard seismic processing work flow.

Maharramov, Musa

2012-01-01

67

Corrosion Study of Zinc, Nickel, and Zinc-Nickel Alloys in Alkaline Solutions by Tafel Plot and Impedance Techniques  

Science.gov (United States)

The article describes the use of Tafel plot and electrochemical impedance spectroscopy (EIS) techniques, in order to study the corrosion process of pure zinc, nickel, and synthetic Zn-Ni alloys in various concentrations (0.25 to 1 M) of KOH solution in a temperature range 298 K to 328 K (25 °C to 55 °C). The corrosion rate increases with increasing both concentration of KOH and temperature for all investigated electrodes. The results showed that the increase in Ni content improves the corrosion resistance and increases the barrier of activation energy, and the higher value of corrosion resistance is obtained at 10 pct Ni. The electrochemical measurements using two mentioned techniques are in good agreement with the results of microhardness in that the microhardness gradually increases with increasing Ni content in the alloy. Thus, the corrosion rate of these alloys is significantly reduced compared with that of pure zinc. It is observed that the Warburg tail at low frequency completely disappears at the applied potentials in the case of alloy IV (10 pct Ni) only. This indicates that the diffusion of Zn ion species is strongly reduced. Therefore, addition of Ni to Zn has a beneficial effect, because it leads to lower loss of anode material. The results obtained at certain positive potential (+420 mV vs SCE) exhibited that the semicircle diameter in the case of alloys is lower compared with that of pure zinc. This result means that the values of the charge transfer resistance ( R ct ) in the case of alloys are decreased, due to the breakdown of the oxide layer at this potential. This behavior can be considered as an important criterion for a good battery anode, due to reactivation of the alloy surface at certain positive potential (+0.420 V vs SCE) and suppression of hydrogen gas compared with those of pure zinc.

El-Sayed, Abdel-Rahman; Mohran, Hossnia S.; Abd El-Lateef, Hany M.

2012-02-01

68

Chiral extrapolation beyond the power-counting regime  

International Nuclear Information System (INIS)

Chiral effective field theory can provide valuable insight into the chiral physics of hadrons when used in conjunction with nonperturbative schemes such as lattice quantum chromodynamics (QCD). In this discourse, the attention is focused on extrapolating the mass of the ? meson to the physical pion mass in quenched QCD. With the absence of a known experimental value, this serves to demonstrate the ability of the extrapolation scheme to make predictions without prior bias. By using extended effective field theory developed previously, an extrapolation is performed using quenched lattice QCD data that extends outside the chiral power-counting regime. The method involves an analysis of the renormalization flow curves of the low-energy coefficients in a finite-range regularized effective field theory. The analysis identifies an optimal regularization scale, which is embedded in the lattice QCD data themselves. This optimal scale is the value of the regularization scale at which the renormalization of the low-energy coefficients is approximately independent of the range of quark masses considered. By using recent precision, quenched lattice results, the extrapolation is tested directly by truncating the analysis to a set of points above 380 MeV, while temporarily disregarding the simulation results closer to the chiral regime. This tests the ability of the method to make predictions of the simulation results, without phenomenologically motivated bias. The result is a succally motivated bias. The result is a successful extrapolation to the chiral regime.

69

AXES OF EXTRAPOLATION IN RISK ASSESSMENTS  

Science.gov (United States)

Extrapolation in risk assessment involves the use of data and information to estimate or predict something that has not been measured or observed. Reasons for extrapolation include that the number of combinations of environmental stressors and possible receptors is too large to c...

70

Chiral extrapolation beyond the power-counting regime  

CERN Document Server

Chiral effective field theory can provide valuable insight into the chiral physics of hadrons when used in conjunction with non-perturbative schemes such as lattice QCD. In this discourse, the attention is focused on extrapolating the mass of the rho meson to the physical pion mass in quenched QCD (QQCD). With the absence of a known experimental value, this serves to demonstrate the ability of the extrapolation scheme to make predictions without prior bias. By using extended effective field theory developed previously, an extrapolation is performed using quenched lattice QCD data that extends outside the chiral power-counting regime (PCR). The method involves an analysis of the renormalization flow curves of the low energy coefficients in a finite-range regularized effective field theory. The analysis identifies an optimal regulator, which is embedded in the lattice QCD data themselves. This optimal regulator is the regulator value at which the renormalization of the low energy coefficients is approximately i...

Hall, J M M; Leinweber, D B; Liu, K F; Mathur, N; Young, R D; Zhang, J B

2011-01-01

71

Finite-range regularisation and chiral extrapolation  

International Nuclear Information System (INIS)

We study the expansion of the nucleon mass in chiral effective field theory. We describe finite-range regularisation and demonstrate its application to the chiral extrapolation problem for lattice QCD

72

Hot particle dosimetry using extrapolation chambers and radiochromic foils  

International Nuclear Information System (INIS)

Results are presented of a comparison between extrapolation chambers and radiochromic foils for the dosimetry of small radio-active (''hot'') particles. While it is possible to measure average dose over arbitrary areas using both methods, the radiochromic foil method has the advantage of displaying full two-dimensional dose distributions with a single measurement. With multiple layers of foils, three dimensional dose distributions are measurable. The foils used employ a new, relatively sensitive emulsion which is 6-8 ?m thick and coated on a 0.1 mm thick polyester base. They require no processing; upon irradiation a very fine-grained, stable, blue image forms which is nearly linear over an absorbed dose range of 0.05 to 1.2 kGy. The readout is done with a scanning laser microdensitometer. The foils used for this study were calibrated using 90Sr/90Y beta particle spectra and were found to respond nearly identically to 60Co gamma rays. Results from such radiochromic foil measurements are compared with measurements with the same source using an extrapolation chamber. Pitfalls in the use of extrapolation chambers for these surface dose rate measurements are explored, including the effect of non-linear current relative to air gap functions on extrapolated slopes. (author)

73

Systematic expansion for infrared oscillator basis extrapolations  

CERN Document Server

Recent work has demonstrated that the infrared effects of harmonic oscillator basis truncations are well approximated by imposing a partial-wave Dirichlet boundary condition at a properly identified radius L. This led to formulas for extrapolating the corresponding energy E_L and other observables to infinite L and thus infinite basis size. Here we reconsider the energy for a two-body system with a Dirichlet boundary condition at L to identify and test a consistent and systematic expansion for E_L that depends only on observables. We also generalize the energy extrapolation formula to nonzero angular momentum, and apply it to the deuteron. Formulas given previously for extrapolating the radius are derived in detail.

Furnstahl, R J; More, S N

2013-01-01

74

Essentially nonoscillatory (ENO) reconstructions via extrapolation  

Science.gov (United States)

In this paper, the algorithm for determining the stencil of a one-dimensional Essentially Nonoscillatory (ENO) reconstruction scheme on a uniform grid is reinterpreted as being based on extrapolation. This view leads to another extension of ENO reconstruction schemes to two-dimensional unstructured triangular meshes. The key idea here is to select several cells of the stencil in one step based on extrapolation rather than one cell at a time. Numerical experiments confirm that the new scheme yields sharp nonoscillatory reconstructions and that it is about five times faster than previous schemes.

Suresh, Ambady; Jorgenson, Philip C. E.

1995-01-01

75

Methodology for extrapolation of rock mass deformability parameters in tunneling  

Directory of Open Access Journals (Sweden)

Full Text Available This article proposes one approach for extrapolation of necessary parameters for numerical analyses in tunnelling. The approach is named as an empirical - statical - dynamical method for extrapolation. The proposed methodology is based on combination of empirical classification rock mass methods, geophysical measurements and direct dilatometer deformability testing on a field. The analyses are prepared for purposes of investigation and design for several tunnels in Republic of Macedonia. One example for dividing of tunnel length in quasi-homogenous zones, as a basis for forming of geotechnical and numerical model that can be a basis for interaction analyses of rock - structures system and stress-strain behaviour of rock massif, is also given. The several original regressive models between rock mass quality, deformability and velocity of longitudinal seismic waves are shown.

Zafirovski Zlatko

2012-01-01

76

Cosmogony as an extrapolation of magnetospheric research  

International Nuclear Information System (INIS)

A theory of the origin and evolution of the Solar System (Alfven and Arrhenius, 1975: 1976) which considered electromagnetic forces and plasma effects is revised in the light of new information supplied by space research. In situ measurements in the magnetospheres and solar wind have changed our views of basic properties of cosmic plasmas. These results can be extrapolated both outwards in space, to interstellar clouds, backwards in time, to the formation of the solar system. The first extrapolation leads to a revision of some cloud properties which are essential for the early phases in the formation of stars and solar nebule. The latter extrapolation makes possible to approach the cosmogonic processes by extrapolation of (rather) well-known magnetospheric phenomena. Pioneer-Voyager observations of the Saturnian rings indicate that essential parts of their structure are fossils from cosmogonic times. By using detailed information from these space missions, it seems possible to reconstruct certain events 4-5 billion years ago with an accuracy of a few percent. This will cause a change in our views of the evolution of the solar system.(author)

77

Interpolation and Extrapolation of Precipitation Quantities in Serbia  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this paper is to indicate the problems with filling the missing data in precipitation database using interpolation and extrapolation methods. Investigated periods were from 1981 to 2010 for Northern (Autonomous Province of Vojvodina and Proper Serbia and from 1971 to 2000 for Southern Serbia (Autonomous Province of Kosovo and Metohia. Database included time series from 78 meteorological stations that had less than 20% of missing data. Interpolation was performed if station had missing data for five consecutive months or less. If station had missing data for six consecutive months or more, extrapolation was performed. For every station with mising data correlation with at least three surrounding stations was performed. The lowest acceptable value of correlation coefficient for precipitation was set at 0,300

Rastislav Stojsavljevi?

2013-01-01

78

Evaluation of uncertainty in vertical extrapolation of wind speeds and its implications  

Energy Technology Data Exchange (ETDEWEB)

This paper reported on a study that investigated the influence that topography, surface roughness and atmospheric stability have on wind speed vertical extrapolation and the financial impact throughout the service life of a wind power project. The wind resource should be assessed at hub height in order to calculate the energy yield of a wind turbine and the noise propagation or to determine the structural integrity of a wind tower. The accuracy of the hub height wind speed estimate depends on how well the vertical extrapolation has been done. In this study, directionally, monthly and hourly computed wind shear coefficients were used to extrapolate the measured wind speeds to hub height in order to compare extrapolated and measured wind speed values under different conditions. Boundary layer equations were used to evaluate the atmospheric stability. Wind speeds were extrapolated using the appropriate stability correction function and were verified against measured wind speeds. Different methods to define the stability classes were compared with the measured data. Several WAsP simulations were run with measured and extrapolated wind series in order to evaluate the influence of vertical extrapolation on the horizontal distribution of the wind resource. All evaluated extrapolation methods performed well, with uncertainty of up to 3 per cent for studied cases. The uncertainty was lower in less complex conditions and when more measured data was available. Future work will focus on extending validation of the extrapolation methods using other tall tower data in terrain of varying complexity, as well as further investigating the effects of stability on extrapolation. 8 refs., 2 tabs., 10 figs.

Dimitrijevic, M.; Zaganescu, C.; Dokouzian, S. [Helimax Energy Inc., Montreal, PQ (Canada)

2008-07-01

79

Monitoring corrosion and corrosion control of iron in HCl by non-ionic surfactants of the TRITON-X series - Part I. Tafel polarisation, ICP-AES and EFM studies  

International Nuclear Information System (INIS)

The corrosion inhibition characteristics of non-ionic surfactants of the TRITON-X series, known as TRITON-X-100 (TX-100), TRITON-X-165 (TX-165) and TRITON-X-305 (TX-305), on iron in 1.0 M HCl solution were studied. Measurements were conducted in 1.0 M HCl solutions without and with various concentrations of the three selected surfactants using chemical (ICP-AES method of analysis of dissolved cations) and electrochemical (Tafel polarisation and EFM) techniques at 25 deg. C. These measurements were complemented with SEM and EDX examinations of the electrode surface. Polarisation data showed that the non-ionic surfactants used in this study acted as mixed-type inhibitors with cathodic predominance. The protection efficiency increased with increase in surfactant concentration. Maximum protection efficiency of the surfactant was observed at concentrations around its CMC. From their molecular structure, these surfactants may adsorb on the metal surface through two lone pairs of electrons on the oxygen atoms of the hydrophilic head group.

80

Analysis of ?-p ? ?-p, ?-p ? ?-?0p et ?-p ? ?+?-n reactions at 2,77 GeV/c and study of the ?? elastic scattering by the Chew-Low extrapolation method applied to ?-p ? ?-?0p and ?-p ? ?+?-n reactions  

International Nuclear Information System (INIS)

180000 pictures taken in the 2 m CERN hydrogen bubble chamber with an incident beam of 2.77 GeV/e were examined. High statistics obtained in the whole angular production range allowed to study the d?/dt differential cross section behaviour, the mass and width of the ? meson, and the multipole parameters of this resonance. Nevertheless, the aim of this experiment was the application of the CHEW - LOW extrapolation method. Different types of extrapolation procedures were compared. Phase shift analysis of the elastic ?? scattering between 500 and 1100 MeV, performed with conformal mappings, allowed to determine the values of the S0, S2, P1, D0, D2 waves. Forward dispersion relations were used to obtain scattering length values of the S2 and P1 phase shifts. (author)

 
 
 
 
81

National pattern for the realization of the unit of the dose speed absorbed in air for beta radiation. (Method: Ionometer, cavity of Bragg-Gray implemented in an extrapolation chamber with electrodes of variable separation, exposed to a field of beta radiation of 90Sr/90Y)  

International Nuclear Information System (INIS)

From the year of 1987 the Department of Metrology of the ININ, in their Secondary Laboratory of Calibration Dosimetric, has a patron group of sources of radiation beta and an extrapolation chamber of electrodes of variable separation.Their objective is to carry out of the unit of the dose speed absorbed in air for radiation beta. It uses the ionometric method, cavity Bragg-Gray in the extrapolation chamber with which it counts. The services that offers are: i) it Calibration : Radioactive Fuentes of radiation beta, isotopes: 90Sr/90Y; Ophthalmic applicators 90Sr/90Y; Instruments for detection of beta radiation with to the radiological protection: Ionization chambers, Geiger-Muller, etc.; Personal Dosemeters. ii) Irradiation with beta radiation of materials to the investigation. (Author)

82

Extrapolation of toxic indices among test objects  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Oligochaeta Tubifex tubifex, fish fathead minnow (Pimephales promelas), hepatocytes isolated from rat liver and ciliated protozoan are absolutely different organisms and yet their acute toxicity indices correlate. Correlation equations for special effects were developed for a large heterogeneous series of compounds (QSAR, quantitative structure-activity relationships). Knowing those correlation equations and their statistic evaluation, one can extrapolate the toxic indices. The reason is that...

Tichy?, Milon?; Rucki, Maria?n; Roth, Zdene?k; Hanzli?kova?, Iveta; Vlkova?, Alena; Tumova?, Jana; Uzlova?, Ru?t

2010-01-01

83

Surface dose extrapolation measurements with radiographic film  

International Nuclear Information System (INIS)

Assessment of surface dose delivered from radiotherapy x-ray beams for optimal results should be performed both inside and outside the prescribed treatment fields. An extrapolation technique can be used with radiographic film to perform surface dose assessment for open field high energy x-ray beams. This can produce an accurate two-dimensional map of surface dose if required. Results have shown that the surface percentage dose can be estimated within ±3% of parallel plate ionization chamber results with radiographic film using a series of film layers to produce an extrapolated result. Extrapolated percentage dose assessment for 10 cm, 20 cm and 30 cm square fields was estimated to be 15% ± 2%, 29% ± 3% and 38% ± 3% at the central axis and relatively uniform across the treatment field. The corresponding parallel plate ionization chamber measurements are 16%, 27% and 37%, respectively. Surface doses are also measured outside the treatment field which are mainly due to scattered electron contamination. To achieve this result, film calibration curves must be irradiated to similar x-ray field sizes as the experimental film to minimize quantitative variations in film optical density caused by varying x-ray spectrum with field size. (note)

84

Effective Orthorhombic Anisotropic Models for Wave field Extrapolation  

Wavefield extrapolation in orthorhombic anisotropic media incorporates complicated but realistic models, to reproduce wave propagation phenomena in the Earth\\'s subsurface. Compared with the representations used for simpler symmetries, such as transversely isotropic or isotropic, orthorhombic models require an extended and more elaborated formulation that also involves more expensive computational processes. The acoustic assumption yields more efficient description of the orthorhombic wave equation that also provides a simplified representation for the orthorhombic dispersion relation. However, such representation is hampered by the sixth-order nature of the acoustic wave equation, as it also encompasses the contribution of shear waves. To reduce the computational cost of wavefield extrapolation in such media, I generate effective isotropic inhomogeneous models that are capable of reproducing the first-arrival kinematic aspects of the orthorhombic wavefield. First, in order to compute traveltimes in vertical orthorhombic media, I develop a stable, efficient and accurate algorithm based on the fast marching method. The derived orthorhombic acoustic dispersion relation, unlike the isotropic or transversely isotropic one, is represented by a sixth order polynomial equation that includes the fastest solution corresponding to outgoing P-waves in acoustic media. The effective velocity models are then computed by evaluating the traveltime gradients of the orthorhombic traveltime solution, which is done by explicitly solving the isotropic eikonal equation for the corresponding inhomogeneous isotropic velocity field. The inverted effective velocity fields are source dependent and produce equivalent first-arrival kinematic descriptions of wave propagation in orthorhombic media. I extrapolate wavefields in these isotropic effective velocity models using the more efficient isotropic operator, and the results compare well, especially kinematically, with those obtained from the more expensive anisotropic extrapolator.

Ibanez Jacome, Wilson

2013-05-01

85

Extrapolation of Creep Test Results Accounting for Long Term Material Degradation.  

Science.gov (United States)

A universal creep equation is shown to form the basis of a creep extrapolation method which accounts for long term material degradation but which makes use of separate parameters for creep and material degradation.

H. P. Vanleeuwen

1977-01-01

86

Response Load Extrapolation for Wind Turbines during Operation Based on Average Conditional Exceedance Rates  

DEFF Research Database (Denmark)

The paper explores a recently developed method for statistical response load (load effect) extrapolation for application to extreme response of wind turbines during operation. The extrapolation method is based on average conditional exceedance rates and is in the present implementation restricted to cases where the Gumbel distribution is the appropriate asymptotic extreme value distribution. However, two extra parameters are introduced by which a more general and flexible class of extreme value distributions is obtained with the Gumbel distribution as a subclass. The general method is implemented within a hierarchical model where the variables that influence the loading are divided into ergodic variables and time-invariant non-ergodic variables. The presented method for statistical response load extrapolation was compared with the existing methods based on peak extrapolation for the blade out-of-plane bending moment and the tower mudline bending moment of a pitch-controlled wind turbine. In general, the results show that the method based on average conditional exceedance rates predicts the extrapolated characteristic response loads at the individual mean wind speeds well and results in more consistent estimates than the methods based on peak extrapolation.

Toft, Henrik Stensgaard; Naess, Arvid

2011-01-01

87

On extrapolation blowups in the scale  

Directory of Open Access Journals (Sweden)

Full Text Available Yano's extrapolation theorem dated back to 1951 establishes boundedness properties of a subadditive operator acting continuously in for close to and/or taking into as and/or with norms blowing up at speed and/or , . Here we give answers in terms of Zygmund, Lorentz-Zygmund and small Lebesgue spaces to what happens if as . The study has been motivated by current investigations of convolution maximal functions in stochastic analysis, where the problem occurs for . We also touch the problem of comparison of results in various scales of spaces.

Fiorenza Alberto

2006-01-01

88

Chiral and Continuum Extrapolation of Partially-Quenched Hadron Masses  

CERN Document Server

Using the finite-range regularisation (FRR) of chiral effective field theory, the chiral extrapolation formula for the vector meson mass is derived for the case of partially-quenched QCD. We re-analyse the dynamical fermion QCD data for the vector meson mass from the CP-PACS collaboration. A global fit, including finite lattice spacing effects, of all 16 of their ensembles is performed. We study the FRR method together with a naive polynomial approach and find excellent agreement ~1% with the experimental value of M_rho from the former approach. These results are extended to the case of the nucleon mass.

Allton, C R; Leinweber, D B; Thomas, A W; Young, R D

2005-01-01

89

Calculation of angle-dependent extrapolation lengths at the control channel edge of absorber assemblies  

International Nuclear Information System (INIS)

Based on a model formulated within the framework of two-group diffusion equation for the absorber section of WWER-440 type control elements and the Fourier series expansion of the corresponding solution of the modified one-group diffusion approximation, the extrapolation length on the control channel edge is investigated as a function of angle for an absorber eccentrically positioned in a homogeneous cylindrical reactor core. The angle-depending extrapolation length is shown to be calculable in a sufficient approximation from absorber-specific parameters and a flux distribution resulting from the assumption of a constant extrapolation length. The method of calculating angle-dependent extrapolation lengths is transferred onto the coarse-mesh difference schema method of the one-group diffusion equation and is also appropriate for a more exact consideration of heterogeneous core configurations. (author)

90

In situ LTE exposure of the general public: Characterization and extrapolation.  

Science.gov (United States)

In situ radiofrequency (RF) exposure of the different RF sources is characterized in Reading, United Kingdom, and an extrapolation method to estimate worst-case long-term evolution (LTE) exposure is proposed. All electric field levels satisfy the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels with a maximal total electric field value of 4.5 V/m. The total values are dominated by frequency modulation (FM). Exposure levels for LTE of 0.2 V/m on average and 0.5 V/m maximally are obtained. Contributions of LTE to the total exposure are limited to 0.4% on average. Exposure ratios from 0.8% (LTE) to 12.5% (FM) are obtained. An extrapolation method is proposed and validated to assess the worst-case LTE exposure. For this method, the reference signal (RS) and secondary synchronization signal (S-SYNC) are measured and extrapolated to the worst-case value using an extrapolation factor. The influence of the traffic load and output power of the base station on in situ RS and S-SYNC signals are lower than 1 dB for all power and traffic load settings, showing that these signals can be used for the extrapolation method. The maximal extrapolated field value for LTE exposure equals 1.9 V/m, which is 32 times below the ICNIRP reference levels for electric fields. PMID:22271226

Joseph, Wout; Verloock, Leen; Goeminne, Francis; Vermeeren, Günter; Martens, Luc

2012-09-01

91

Scintillation counting: an extrapolation into the future  

International Nuclear Information System (INIS)

Progress in scintillation counting is intimately related to advances in a variety of other disciplines such as photochemistry, photophysics, and instrumentation. And while there is steady progress in the understanding of luminescent phenomena, there is a virtual explosion in the application of semiconductor technology to detectors, counting systems, and data processing. The exponential growth of this technology has had, and will continue to have, a profound effect on the art of scintillation spectroscopy. This paper will review key events in technology that have had an impact on the development of scintillation science (solid and liquid) and will attempt to extrapolate future directions based on existing and projected capability in associated fields. Along the way there have been occasional pitfalls and several false starts; these too will be discussed as a reminder that if you want the future to be different than the past, study the past

92

Edge database analysis for extrapolation to ITER  

International Nuclear Information System (INIS)

An edge database has been archived to facilitate cross-machine comparisons of SOL and edge pedestal characteristics, and to enable comparison with theoretical models with an aim to extrapolate to ITER. The SOL decay lengths of power, density and temperature become broader for increasing density and q95 . The power decay length is predicted to be 1.4-3.5 cm (L-mode) and 1.4-2.7 cm (H-mode) at the midplane in ITER. Analysis of Type I ELMs suggests that each giant ELM on ITER would exceed the ablation threshold of the divertor plates. Theoretical models are proposed for the H-mode transition, for Type I and Type III ELMs and are compared with the edge pedestal database. (author)

93

The extrapolation of creep rupture data by PD6605 - An independent case study  

International Nuclear Information System (INIS)

The worked example presented in BSI document PD6605-1:1998, to illustrate the selection, validation and extrapolation of a creep rupture model using statistical analysis, was independently examined. Alternative rupture models were formulated and analysed by the same statistical methods, and were shown to represent the test data more accurately than the original model. Median rupture lives extrapolated from the original and alternative models were found to diverge widely under some conditions of practical interest. The tests prescribed in PD6605 and employed to validate the original model were applied to the better of the alternative models. But the tests were unable to discriminate between the two, demonstrating that these tests fail to ensure reliability in extrapolation. The difficulties of determining when a model is sufficiently reliable for use in extrapolation are discussed and some proposals are made.

94

The extrapolation of creep rupture data by PD6605 - An independent case study  

Energy Technology Data Exchange (ETDEWEB)

The worked example presented in BSI document PD6605-1:1998, to illustrate the selection, validation and extrapolation of a creep rupture model using statistical analysis, was independently examined. Alternative rupture models were formulated and analysed by the same statistical methods, and were shown to represent the test data more accurately than the original model. Median rupture lives extrapolated from the original and alternative models were found to diverge widely under some conditions of practical interest. The tests prescribed in PD6605 and employed to validate the original model were applied to the better of the alternative models. But the tests were unable to discriminate between the two, demonstrating that these tests fail to ensure reliability in extrapolation. The difficulties of determining when a model is sufficiently reliable for use in extrapolation are discussed and some proposals are made.

Bolton, J., E-mail: john.bolton@uwclub.net [65 Fisher Avenue, Rugby, Warks CV22 5HW (United Kingdom)

2011-04-15

95

Waveform Inversion by One-way Wavefield Extrapolation  

Science.gov (United States)

Forward modeling in frequency-domain waveform inversion is often implemented using finite difference (FD) methods. However, the cost of FD modeling remains too expensive for typical 3D seismic data volumes. One- way wavefield extrapolation is one alternative strategy considerably cheaper to implement. This approach, though, comes with caveats that typically include lower accuracy at steep propagation angles in laterally varying media, a difficulty for incorporating source radiation patterns, and an inability to propagate turning or multiply reflected waves. Each of these factors can play a role in determining the success or failure of a waveform inversion analysis. This study examines the potential for using one-way Riemannian wavefield extrapolation (RWE) operators in the forward modeling component of frequency-domain waveform inversion. RWE is carried out on computational meshes designed to conform to the general direction of turning-wave propagation, which enables the calculation of the direct arrivals, wide-angle reflections and refractions important for a successful waveform inversion. The waveform inversion procedure otherwise closely resembles the frequency-domain approach of Pratt. Forward modeling test results indicate that RWE waveforms match fairly well with those generated by FD modeling fairly at wider offsets. Preliminary tests of the RWE waveform inversion scheme demonstrate its ability to invert FD-generated synthetic data for moderate (10%) 1D velocity perturbations.

Shragge, J. C.

2006-12-01

96

Hard hadronic collisions: extrapolation of standard effects  

Energy Technology Data Exchange (ETDEWEB)

We study hard hadronic collisions for the proton-proton (pp) and the proton-antiproton (p anti p) option in the CERN LEP tunnel. Based on our current knowledge of hard collisions at the present CERN p anti p Collider, and with the help of quantum chromodynamics (QCD), we extrapolate to the next generation of hadron colliders with a centre-of-mass energy E/sub cm/ = 10 to 20 TeV. We estimate various signatures, trigger rates, event topologies, and associated distributions for a variety of old and new physical processes, involving prompt photons, leptons, jets, W/sup + -/ and Z bosons in the final state. We also calculate the maximum fermion and boson masses accessible at the LEP Hadron Collider. The standard QCD and electroweak processes studied here, being the main body of standard hard collisions, quantify the challenge of extracting new physics with hadron colliders. We hope that our estimates will provide a useful profile of the final states, and that our experimental physics colleagues will find this of use in the design of their detectors. 84 references.

Ali, A.; Aurenche, P.; Baier, R.; Berger, E.; Douiri, A.; Fontannaz, M.; Humpert, B.; Ingelman, G.; Kinnunen, R.; Pietarinen, E.

1984-01-01

97

Towards a Thomas-Fermi mass formula for extrapolation to the neutron-drip line  

International Nuclear Information System (INIS)

For an analysis of the r-process of stellar nucleosynthesis, binding energies of the unknown nuclei close to the neutron drip line are required. The way to get these energies is to use the nuclear mass formula to extrapolate from the known nuclei to the unknown nuclei close to the neutron-drip line. It is observed that the mass formulas based on existing forms of the droplet model (DM) extrapolate very badly out to the neutron-drip line, but a mass formula based on the Extended Thomas-Fermi (ETF) method with Skyrme-type force extrapolates out to the neutron-drip line almost as well as the Hartree-Fock (HF) method and is computationally much faster than HF method. (M.G.B.)

98

Dose rates from a C-14 source using extrapolation chamber and MC calculations  

International Nuclear Information System (INIS)

The extrapolation chamber technique and the Monte Carlo (MC) calculation technique based on the EGS4 system have been studied for application for determination of dose rates in a low-energy ? radiation field e.g., that from a 14C source. The extrapolation chamber measurement method is the basic method for determination of dose rates in ? radiation fields. Applying a number of correction factors and the stopping power ratio, tissue to air, the measured dose rate in an air volume surrounded by tissue equivalent material is converted into dose to tissue. Various details of the extrapolation chamber measurement method and evaluation procedure have been studied and further developed, and a complete procedure for the experimental determination of dose rates from a14C source is presented. A number of correction factors and other parameters used in the evaluation procedure for the measured data have been obtained by MC calculations. The whole extrapolation chamber measurement procedure was simulated using the MC method. The measured dose rates showed an increasing deviation from the MC calculated dose rates as the absorber thickness increased. This indicates that the EGS4 code may have some limitations for transport of very low-energy electrons. i.e., electrons with estimated energies less than 10 - 20 keV. MC calculations of dose to tissue were performed using two models: a cylindrical tissue phantom and a computer model of the extrapolation chamber. The dose to tissue in the extrapolation chamber model showed an additional buildup dose compared to the dose in the tissue model. (au) 10 tabs., 11 ills., 18 refs

99

A physically based methodology to extrapolate performance maps of radial turbines  

International Nuclear Information System (INIS)

Highlights: ? Physical based methodology to extrapolate radial turbine efficiency measured data. ? Equation relating efficiency versus blade to speed ratio (?) have been developed. ? Developed efficiency equation takes into account turbine mass flow parameter. ? Efficiency versus ? at constant pressure ratio is discussed, also at constant speed. ? The methodology has been validated with a broad range of experimental results. - Abstract: This paper details a physically based methodology to perform an extrapolation of the radial turbine performance maps, both mass flow characteristics and the efficiency curve. This method takes into account a narrow range of experimental data, which is usually the data available when such turbines are part of a turbocharger. Therefore, the extrapolation methodology is especially useful when data from third parties are being used or when the compressor of a turbocharger is used as the turbine brake in a gas stand. The nozzle equation is used to develop an interpolation and extrapolation of the mass flow rate trough the turbine. Then, specific information is extracted from this extrapolation and is fed into a total-to-static efficiency equation to carry out an extension of the efficiency curve. This equation is developed using the definition of the total-to-static efficiency, velocity triangles and thermodynamic and fluid fundamental equations. This procedure has been applied to five radial turbines of different sizes and types. Results are compared against experimental information available in the literature or provided by the turbine manufacturers and a good agreement has been found between theoretical and experimentally estimated data.

100

Slow neutron flux extrapolation distances in R-5 and CIRUS reactors  

International Nuclear Information System (INIS)

In order to calculate the core reactivity, fuel channel power outputs and neutron flux levels in the R-5 reactor at Trombay, axial flux extrapolation distances are required. For this, an analysis is carried out considering the reactor core as a two region neutron multiplying system in axial direction. The slow neutron diffusion equations for both the regions are solved analytically by applying suitable boundary conditions. Application of this method for the estimation of top extrapolation distances in CIRUS, has given results which agree well with accepted values for the reactor. (author)

 
 
 
 
101

Thermal neutron extrapolation distances for slabs of beryllium and water  

International Nuclear Information System (INIS)

Extrapolation distances for thermal neutrons have been obtained for slabs of beryllium and light water by minimising the difference between the steady-state leakage spectra calculated on the basis of diffusion and transport theories. Using the present values of extrapolation distance ensures that neutron spectra (both in beryllium and water) calculated on the basis of diffusion theory agree well with the corresponding transport theory spectra, even at distances close to the free surface. The extrapolation distance is found to be dependent on the thickness of the slab, increasing with increase in the thickness. (author)

102

Border extrapolation using fractal attributes in remote sensing images  

Science.gov (United States)

In management, monitoring and rational use of natural resources the knowledge of precise and updated information is essential. Satellite images have become an attractive option for quantitative data extraction and morphologic studies, assuring a wide coverage without exerting negative environmental influence over the study area. However, the precision of such practice is limited by the spatial resolution of the sensors and the additional processing algorithms. The use of high resolution imagery (i.e., Ikonos) is very expensive for studies involving large geographic areas or requiring long term monitoring, while the use of less expensive or freely available imagery poses a limit in the geographic accuracy and physical precision that may be obtained. We developed a methodology for accurate border estimation that can be used for establishing high quality measurements with low resolution imagery. The method is based on the original theory by Richardson, taking advantage of the fractal nature of geographic features. The area of interest is downsampled at different scales and, at each scale, the border is segmented and measured. Finally, a regression of the dependence of the measured length with respect to scale is computed, which then allows for a precise extrapolation of the expected length at scales much finer than the originally available. The method is tested with both synthetic and satellite imagery, producing accurate results in both cases.

Cipolletti, M. P.; Delrieux, C. A.; Perillo, G. M. E.; Piccolo, M. C.

2014-01-01

103

Associação de cetamina S(+) e midazolam pelo método convencional de cálculo e pela extrapolação alométrica em bugios-ruivo (Alouatta guariba clamitans): resposta clínica e cardiorrespiratória / S(+) ketamine and midazolam association by the conventional method of calculation and allometric extrapolation in red howler monkeys (Alouatta guariba clamitans): clinical and cardiopulmonary response  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste estudo foi avaliar o protocolo de contenção química com cetamina S(+) e midazolam em bugios-ruivos, comparando o cálculo de doses pelo método convencional e o método de extrapolação alométrica. Foram utilizados 12 macacos bugios (Alouatta guariba clamitans) hígidos, com peso médio d [...] e 4,84±0,97kg, de ambos os sexos. Após jejum alimentar de 12 horas e hídrico de seis horas, realizou-se contenção física manual e aferiram-se os seguintes parâmetros: frequência cardíaca (FC), frequência respiratória (f), tempo de preenchimento capilar (TPC), temperatura retal (TR), pressão arterial sistólica não invasiva (PANI) e valores de hemogasometria arterial. Posteriormente, os animais foram alocados em dois grupos: GC (Grupo Convencional, n=06), os quais receberam cetamina S(+) (5mg kg-1) e midazolam (0,5mg kg-1), pela via intramuscular, com doses calculadas pelo método convencional; e GA (Grupo Alometria, n=06), os quais receberam o mesmo protocolo, pela mesma via, utilizando-se as doses calculadas pelo método de extrapolação alométrica. Os parâmetros descritos foram mensurados novamente nos seguintes momentos: M5, M10, M20 e M30 (cinco, 10, 20 e 30 minutos após a administração dos fármacos, respectivamente). Também foram avaliados: qualidade de miorrelaxamento, reflexo podal e caudal, pinçamento interdigital, tempo para indução de decúbito, tempo hábil de sedação, qualidade de sedação, e tempo e qualidade de recuperação. O GA apresentou menor tempo para indução ao decúbito, maior grau e tempo de sedação, bem como redução significativa da FC e PANI de M5 até M30, quando comparado ao GC. Conclui-se que o grupo no qual o cálculo de dose foi realizado por meio da alometria (GA) apresentou melhor grau de relaxamento muscular e sedação, sem produzir depressão cardiorrespiratória significativa. Abstract in english The aim of this study was to evaluate a protocol of chemical restraint comparing the conventional method of calculation (weight dose) and allometric extrapolation. Twelve healthy red howler monkeys (Alouatta guariba clamitans), average weight 4.84±0.97kg, male and female, were used for this study. A [...] fter a 12-hour period of food restriction and 6 hours of water restriction, the animals were physically restraint and the following parameters were measured: heart rate (HR), respiratory rate (RR), capillary refill time (CRT), rectal temperature (RT), non invasive systolic arterial pressure (NISAP) and arterial blood gases analysis. The animals were distributed into two groups: CG (Conventional Group, n=6), in which the animals received S(+) ketamine (5mg kg-1) and midazolam (0.5mg kg-1), by intramuscular (IM) injection; and AG (Allometry Group, n=6), in which the animals also received S(+) ketamine and midazolan IM, but the doses were calculated by allometric extrapolation. Parameters were evaluated at the following moments: M5, M10, M20 and M30 (5, 10, 20 and 30 minutes after IM injection, respectively). Muscle relaxation, pedal and caudal reflexes, interdigital pinch, recumbency time, sedation's quality and duration, and recovery time and its quality were also evaluated. The AG had a faster time for recumbency, higher period and quality of sedation, and a significantly reduction on HR and SAP from M5 to M30 when compared to CG. It was concluded that allometric extrapolation presented a better muscle relaxation and sedation without significant cardiorespiratory depression.

Joana Aurora Braun, Chagas; Nilson, Oleskovicz; Aury Nunes de, Moraes; Fabíola Niederauer, Flôres; André Luís, Corrêa; Júlio César, Souza Júnior; André Vasconcelos, Soares; Átila, Costa.

2010-02-01

104

Associação de cetamina S(+ e midazolam pelo método convencional de cálculo e pela extrapolação alométrica em bugios-ruivo (Alouatta guariba clamitans: resposta clínica e cardiorrespiratória S(+ ketamine and midazolam association by the conventional method of calculation and allometric extrapolation in red howler monkeys (Alouatta guariba clamitans: clinical and cardiopulmonary response  

Directory of Open Access Journals (Sweden)

Full Text Available O objetivo deste estudo foi avaliar o protocolo de contenção química com cetamina S(+ e midazolam em bugios-ruivos, comparando o cálculo de doses pelo método convencional e o método de extrapolação alométrica. Foram utilizados 12 macacos bugios (Alouatta guariba clamitans hígidos, com peso médio de 4,84±0,97kg, de ambos os sexos. Após jejum alimentar de 12 horas e hídrico de seis horas, realizou-se contenção física manual e aferiram-se os seguintes parâmetros: frequência cardíaca (FC, frequência respiratória (f, tempo de preenchimento capilar (TPC, temperatura retal (TR, pressão arterial sistólica não invasiva (PANI e valores de hemogasometria arterial. Posteriormente, os animais foram alocados em dois grupos: GC (Grupo Convencional, n=06, os quais receberam cetamina S(+ (5mg kg-1 e midazolam (0,5mg kg-1, pela via intramuscular, com doses calculadas pelo método convencional; e GA (Grupo Alometria, n=06, os quais receberam o mesmo protocolo, pela mesma via, utilizando-se as doses calculadas pelo método de extrapolação alométrica. Os parâmetros descritos foram mensurados novamente nos seguintes momentos: M5, M10, M20 e M30 (cinco, 10, 20 e 30 minutos após a administração dos fármacos, respectivamente. Também foram avaliados: qualidade de miorrelaxamento, reflexo podal e caudal, pinçamento interdigital, tempo para indução de decúbito, tempo hábil de sedação, qualidade de sedação, e tempo e qualidade de recuperação. O GA apresentou menor tempo para indução ao decúbito, maior grau e tempo de sedação, bem como redução significativa da FC e PANI de M5 até M30, quando comparado ao GC. Conclui-se que o grupo no qual o cálculo de dose foi realizado por meio da alometria (GA apresentou melhor grau de relaxamento muscular e sedação, sem produzir depressão cardiorrespiratória significativa.The aim of this study was to evaluate a protocol of chemical restraint comparing the conventional method of calculation (weight dose and allometric extrapolation. Twelve healthy red howler monkeys (Alouatta guariba clamitans, average weight 4.84±0.97kg, male and female, were used for this study. After a 12-hour period of food restriction and 6 hours of water restriction, the animals were physically restraint and the following parameters were measured: heart rate (HR, respiratory rate (RR, capillary refill time (CRT, rectal temperature (RT, non invasive systolic arterial pressure (NISAP and arterial blood gases analysis. The animals were distributed into two groups: CG (Conventional Group, n=6, in which the animals received S(+ ketamine (5mg kg-1 and midazolam (0.5mg kg-1, by intramuscular (IM injection; and AG (Allometry Group, n=6, in which the animals also received S(+ ketamine and midazolan IM, but the doses were calculated by allometric extrapolation. Parameters were evaluated at the following moments: M5, M10, M20 and M30 (5, 10, 20 and 30 minutes after IM injection, respectively. Muscle relaxation, pedal and caudal reflexes, interdigital pinch, recumbency time, sedation's quality and duration, and recovery time and its quality were also evaluated. The AG had a faster time for recumbency, higher period and quality of sedation, and a significantly reduction on HR and SAP from M5 to M30 when compared to CG. It was concluded that allometric extrapolation presented a better muscle relaxation and sedation without significant cardiorespiratory depression.

Joana Aurora Braun Chagas

2010-02-01

105

Pair interaction potentials of colloids by extrapolation of confocal microscopy measurements of collective suspension structure  

Science.gov (United States)

A method for measuring the pair interaction potential between colloidal particles by extrapolation measurement of collective structure to infinite dilution is presented and explored using simulation and experiment. The method is particularly well suited to systems in which the colloid is fluorescent and refractive index matched with the solvent. The method involves characterizing the potential of mean force between colloidal particles in suspension by measurement of the radial distribution function using 3D direct visualization. The potentials of mean force are extrapolated to infinite dilution to yield an estimate of the pair interaction potential, U(r). We use Monte Carlo simulation to test and establish our methodology as well as to explore the effects of polydispersity on the accuracy. We use poly-12-hydroxystearic acid-stabilized poly(methyl methacrylate) particles dispersed in the solvent dioctyl phthalate to test the method and assess its accuracy for three different repulsive systems for which the range has been manipulated by addition of electrolyte.

Iacovella, Christopher R.; Rogers, Reginald E.; Glotzer, Sharon C.; Solomon, Michael J.

2010-10-01

106

Accelerating Monte Carlo Molecular Simulations Using Novel Extrapolation Schemes Combined with Fast Database Generation on Massively Parallel Machines  

We introduce an efficient thermodynamically consistent technique to extrapolate and interpolate normalized Canonical NVT ensemble averages like pressure and energy for Lennard-Jones (L-J) fluids. Preliminary results show promising applicability in oil and gas modeling, where accurate determination of thermodynamic properties in reservoirs is challenging. The thermodynamic interpolation and thermodynamic extrapolation schemes predict ensemble averages at different thermodynamic conditions from expensively simulated data points. The methods reweight and reconstruct previously generated database values of Markov chains at neighboring temperature and density conditions. To investigate the efficiency of these methods, two databases corresponding to different combinations of normalized density and temperature are generated. One contains 175 Markov chains with 10,000,000 MC cycles each and the other contains 3000 Markov chains with 61,000,000 MC cycles each. For such massive database creation, two algorithms to parallelize the computations have been investigated. The accuracy of the thermodynamic extrapolation scheme is investigated with respect to classical interpolation and extrapolation. Finally, thermodynamic interpolation benefiting from four neighboring Markov chains points is implemented and compared with previous schemes. The thermodynamic interpolation scheme using knowledge from the four neighboring points proves to be more accurate than the thermodynamic extrapolation from the closest point only, while both thermodynamic extrapolation and thermodynamic interpolation are more accurate than the classical interpolation and extrapolation. The investigated extrapolation scheme has great potential in oil and gas reservoir modeling.That is, such a scheme has the potential to speed up the MCMC thermodynamic computation to be comparable with conventional Equation of State approaches in efficiency. In particular, this makes it applicable to large-scale optimization of L-J model parameters for hydrocarbons and other important reservoir species. The efficiency of the thermodynamic dependent techniques is expected to make the Markov chains simulation an attractive alternative in compositional multiphase flow simulation.

Amir, Sahar Z.

2013-05-01

107

A new approach for stress rupture data extrapolation  

International Nuclear Information System (INIS)

In the paper a new approach for long time extrapolation of stress rupture data is presented. The main results which first have been applied on SS AISI 304 can be summarized as follows: For long time extrapolation the analytical description of stress rupture lines (SRL) by usual log sigma vs. log tsub(f) diagrams is inappropriate. There are other stress rupture functions F(sigma,tsub(f)) which are more suitable for life time extrapolations. Best results were obtained with a function of the type tsub(f)(sigma) proportional sinh ?sigma. This function allows a better understanding about the nature of the life time determining mechanisms. The analysis of the stress rupture data from SS AISI 304 has shown, that two sequentially dependent mechanisms govern the life time. (orig./RW)

108

Comparing magnetic field extrapolations with measurements of magnetic loops  

CERN Document Server

We compare magnetic field extrapolations from a photospheric magnetogram with the observationally inferred structure of magnetic loops in a newly developed active region. This is the first time that the reconstructed 3D-topology of the magnetic field is available to test the extrapolations. We compare the observations with potential fields, linear force-free fields and non-linear force-free fields. This comparison reveals that a potential field extrapolation is not suitable for a reconstruction of the magnetic field in this young, developing active region. The inclusion of field-line-parallel electric currents, the so called force-free approach, gives much better results. Furthermore, a non-linear force-free computation reproduces the observations better than the linear force-free approximation, although no free parameters are available in the former case.

Wiegelmann, T; Solanki, S K; Inhester, B; Woch, J

2008-01-01

109

Properties of infrared extrapolations in a harmonic oscillator basis  

CERN Document Server

We continue our studies of infrared (ir) and ultraviolet (uv) regulators of no-core shell model calculations. We extend our results that an extrapolation in the ir cutoff with the uv cutoff above the intrinsic uv scale of the interaction is quite successful, not only for the eigenstates of the Hamiltonian but also for expectation values of operators considered long range. The latter results are obtained with Hamiltonians transformed by the similarity renormalization group (SRG) evolution. On the other hand, a suggested extrapolation in the uv cutoff when the ir cutoff is below the intrinsic ir scale is neither robust nor reliable.

Coon, Sidney A

2014-01-01

110

Rubio de Francia's extrapolation theory: estimates for the distribution function  

CERN Document Server

Let $T$ be an arbitrary operator bounded from $L^{p_0}(w)$ into $L^{p_0, \\infty}(w)$ for every weight $w$ in the Muckenhoupt class $A_{p_0}$. It is proved in this article that the distribution function of $Tf$ with respect to any weight $u$ can be essentially majorized by the distribution function of $Mf$ with respect to $u$ (plus an integral term easy to control). As a consequence, well-known extrapolation results, including results in a multilinear setting, can be obtained with very simple proofs. New applications in extrapolation for two-weight problems and estimates on rearrangement invariant spaces are established too.

Carro, María J; Torres, Rodolfo H

2010-01-01

111

Extrapolation of horizontal motion to linear targets of different orientation.  

Science.gov (United States)

In a motion extrapolation task the subjects were asked to press a button at the moment of the imaginary impact between a concealed moving stimulus and a stationary target-line intersecting with the extension of motion trajectory. Horizontal motion of constant velocity was used. The target-line had two possible orientations: vertical and tilted at an angle of 30 degrees with respect to the moving stimulus trajectory. Four extrapolation distances subtending 4.5, 6.0, 7.5, and 9.0 degs of visual angle were used. The target-line was presented 2 s before the disappearance of the moving stimulus. Target-line position and orientation were chosen at random. Four out of five subjects were significantly faster in predicting the impact between the moving stimulus and the tilted target-line. The results are compared to data obtained in line-segment extrapolation experiments and the existence of a common mechanism for spatial extrapolation in static and dynamic conditions is discussed. PMID:3832792

Yakimoff, N

1985-01-01

112

Extrapolation of ZPR sodium void measurements to the power reactor  

International Nuclear Information System (INIS)

Sodium-voiding measurements of ZPPR assemblies 2 and 5 are analyzed with ENDF/B Version IV data. Computations include directional diffusion coefficients to account for streaming effects resulting from the plate structure of the critical assembly. Bias factors for extrapolating critical assembly data to the CRBR design are derived from the results of this analysis

113

Performance characteristics of an extrapolation chamber for beta radiation detection  

International Nuclear Information System (INIS)

The performance of an extrapolation chamber was evaluated in ? radiation fields. The main characteristics such as calibration factors, energy and angular dependence, transmission factors in tissue and source-detector distance dependence have been determined. The influence of the collecting electrode area on the calibration factors was also investigated. (author)

114

Freeze-out parameters from continuum extrapolated lattice data  

CERN Document Server

We present continuum extrapolated lattice results for the higher order fluctuations of conserved charges in high temperature Quantum Chromodynamics. Through the matching of the grand canonical ensemble on the lattice to the net charge and net baryon distribution realized in heavy ion experiments the temperature and the chemical potential may be estimated at the time of chemical freeze-out

Borsanyi, S; Katz, S D; Krieg, S; Ratti, C; Szabo, K K

2013-01-01

115

Modelization of hydrocyclone performance and extrapolation by means of adimensional groups  

Energy Technology Data Exchange (ETDEWEB)

The author presents one approach - chemical engineering - to the modelling of hydrocyclone performance ratings and their extrapolation by means of adimensional groups. The article examines the case of hydrocyclone families of similar geometrical design and of cyclones of different types. He shows that modelling can be achieved as with other methods of solid-liquid modelling: a basic model, whose constants are given, by reduced-scale tests, in an adimensional form. 10 references.

Svarovsky, L.

1984-11-01

116

Routine data sources challenge international diabetes Federation extrapolations of national diabetes prevalence in Switzerland  

Digital Repository Infrastructure Vision for European Research (DRIVER)

OBJECTIVE Information on diabetes prevalence in the general population is scarce and often based on extrapolations. We evaluated whether prevalence could be estimated from routine data sources. RESEARCH DESIGN AND METHODS The sources were 1) hospital discharges (2008, n = 828,171), 2) death registry (2007/2008, n = 118,659), and 3) Swiss Health Survey (SHS; 2007, n = 18,665). Persons without diabetes as underlying cause of death (death registry) or principal diagnosis (hospital discharges) w...

Bopp, Matthias; Zellweger, Ulrich; Faeh, David

2011-01-01

117

Extrapolation of Extreme Response for Wind Turbines based on FieldMeasurements  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The characteristic loads on wind turbines during operation are among others dependent on the mean wind speed, the turbulence intensity and the type and settings of the control system. These parameters must be taken into account in the assessment of the characteristic load. The characteristic load is normally determined by statistical extrapolation of the simulated response during operation according to IEC 61400-1 2005. However, this method assumes that the individual 10 min. time series are ...

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

2009-01-01

118

Comparing Gravitational Waveform Extrapolation to Cauchy-Characteristic Extraction in Binary Black Hole Simulations  

CERN Document Server

We extract gravitational waveforms from numerical simulations of black hole binaries computed using the Spectral Einstein Code. We compare two extraction methods: direct construction of the Newman-Penrose (NP) scalar $\\Psi_4$ at a finite distance from the source and Cauchy-characteristic extraction (CCE). The direct NP approach is simpler than CCE, but NP waveforms can be contaminated by near-zone effects---unless the waves are extracted at several distances from the source and extrapolated to infinity. Even then, the resulting waveforms can in principle be contaminated by gauge effects. In contrast, CCE directly provides, by construction, gauge-invariant waveforms at future null infinity. We verify the gauge invariance of CCE by running the same physical simulation using two different gauge conditions. We find that these two gauge conditions produce the same CCE waveforms but show differences in extrapolated-$\\Psi_4$ waveforms. We examine data from several different binary configurations and measure the domi...

Taylor, Nicholas W; Reisswig, Christian; Scheel, Mark A; Chu, Tony; Kidder, Lawrence E; Szilagyi, Bela

2013-01-01

119

Low-energy particle physics and chiral extrapolations  

CERN Document Server

In this review I discuss the role of chiral extrapolations for the determination of several phenomenologically relevant quantities, including light quark masses, meson decay constants and the axial charge of the nucleon. In particular, I investigate whether chiral extrapolations are sufficiently controlled in order to rightfully claim the accuracy which is quoted in recent compilations of these quantities. While this is the case for the masses of the light quarks and the ratio fK/fpi of decay constants, small inconsistencies in the chiral and continuum behaviour of individual decay constants fK and fpi, as well as the hadronic radii r0, r1 remain and must be clarified. In the case of the nucleon axial charge, gA, the chiral behaviour is still poorly understood due to the presence of other systematic effects.

Wittig, Hartmut

2012-01-01

120

Extrapolation and optimal decompositions with applications to analysis  

CERN Document Server

This book develops a theory of extrapolation spaces with applications to classical and modern analysis. Extrapolation theory aims to provide a general framework to study limiting estimates in analysis. The book also considers the role that optimal decompositions play in limiting inequalities incl. commutator estimates. Most of the results presented are new or have not appeared in book form before. A special feature of the book are the applications to other areas of analysis. Among them Sobolev imbedding theorems in different contexts including logarithmic Sobolev inequalities are obtained, commutator estimates are connected to the theory of comp. compactness, a connection with maximal regularity for abstract parabolic equations is shown, sharp estimates for maximal operators in classical Fourier analysis are derived.

Milman, Mario

1994-01-01

 
 
 
 
121

An efficient extrapolation to the (T)/CBS limit  

Energy Technology Data Exchange (ETDEWEB)

We extrapolate to the perturbative triples (T)/complete basis set (CBS) limit using double ? basis sets without polarization functions (Wesleyan-1-Triples-2? or “Wes1T-2Z”) and triple ? basis sets with a single level of polarization functions (Wesleyan-1-Triples-3? or “Wes1T-3Z”). These basis sets were optimized for 102 species representing the first two rows of the Periodic Table. The species include the entire set of neutral atoms, positive and negative atomic ions, as well as several homonuclear diatomic molecules, hydrides, rare gas dimers, polar molecules, such as oxides and fluorides, and a few transition states. The extrapolated Wes1T-(2,3)Z triples energies agree with (T)/CBS benchmarks to within ±0.65 mE{sub h}, while the rms deviations of comparable model chemistries W1, CBS-APNO, and CBS-QB3 for the same test set are ±0.23 mE{sub h}, ±2.37 mE{sub h}, and ±5.80 mE{sub h}, respectively. The Wes1T-(2,3)Z triples calculation time for the largest hydrocarbon in the G2/97 test set, C{sub 6}H{sub 5}Me{sup +}, is reduced by a factor of 25 when compared to W1. The cost-effectiveness of the Wes1T-(2,3)Z extrapolation validates the usefulness of the Wes1T-2Z and Wes1T-3Z basis sets which are now available for a more efficient extrapolation of the (T) component of any composite model chemistry.

Ranasinghe, Duminda S. [Hall-Atwater Laboratories of Chemistry, Wesleyan University, Middletown, Connecticut 06459-0180 (United States); Barnes, Ericka C., E-mail: barnese8@southernct.edu [Department of Chemistry, Southern Connecticut State University, 501 Crescent Street, New Haven, Connecticut 06515-1355 (United States)

2014-05-14

122

Properties of a commercial extrapolation chamber in ? radiation fields  

International Nuclear Information System (INIS)

A commercial extrapolation chamber was tested in different ? radiation fields and its properties investigated. Its usefulness for ? radiation calibration and dosimetry was verified. Experiments were performed in order to obtain the main characteristics such as the calibration factors (and consequently the energy dependence) for all chamber collecting electrodes (between 10 and 40 mm diameter), the transmission factors in tissue and the useful source-detector distance range

123

Interspecies extrapolation in carcinogenesis: prediction between rats and mice.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Interspecies extrapolation in carcinogenesis is studied by evaluating prediction from rats to mice and from mice to rats. The Carcinogenic Potency Database, which includes 3500 cancer tests conducted in rats or mice on 955 compounds, is used for the analysis. About half of the chemicals tested for carcinogenicity are positive in at least one test, and this proportion is similar when rats and mice are considered separately. For 392 chemicals tested in both species, 76% of the rat carcinogens a...

Gold, L. S.; Bernstein, L.; Magaw, R.; Slone, T. H.

1989-01-01

124

An efficient extrapolation to the (T)/CBS limit  

International Nuclear Information System (INIS)

We extrapolate to the perturbative triples (T)/complete basis set (CBS) limit using double ? basis sets without polarization functions (Wesleyan-1-Triples-2? or “Wes1T-2Z”) and triple ? basis sets with a single level of polarization functions (Wesleyan-1-Triples-3? or “Wes1T-3Z”). These basis sets were optimized for 102 species representing the first two rows of the Periodic Table. The species include the entire set of neutral atoms, positive and negative atomic ions, as well as several homonuclear diatomic molecules, hydrides, rare gas dimers, polar molecules, such as oxides and fluorides, and a few transition states. The extrapolated Wes1T-(2,3)Z triples energies agree with (T)/CBS benchmarks to within ±0.65 mEh, while the rms deviations of comparable model chemistries W1, CBS-APNO, and CBS-QB3 for the same test set are ±0.23 mEh, ±2.37 mEh, and ±5.80 mEh, respectively. The Wes1T-(2,3)Z triples calculation time for the largest hydrocarbon in the G2/97 test set, C6H5Me+, is reduced by a factor of 25 when compared to W1. The cost-effectiveness of the Wes1T-(2,3)Z extrapolation validates the usefulness of the Wes1T-2Z and Wes1T-3Z basis sets which are now available for a more efficient extrapolation of the (T) component of any composite model chemistry

125

An efficient extrapolation to the (T)/CBS limit  

Science.gov (United States)

We extrapolate to the perturbative triples (T)/complete basis set (CBS) limit using double ? basis sets without polarization functions (Wesleyan-1-Triples-2? or "Wes1T-2Z") and triple ? basis sets with a single level of polarization functions (Wesleyan-1-Triples-3? or "Wes1T-3Z"). These basis sets were optimized for 102 species representing the first two rows of the Periodic Table. The species include the entire set of neutral atoms, positive and negative atomic ions, as well as several homonuclear diatomic molecules, hydrides, rare gas dimers, polar molecules, such as oxides and fluorides, and a few transition states. The extrapolated Wes1T-(2,3)Z triples energies agree with (T)/CBS benchmarks to within ±0.65 mEh, while the rms deviations of comparable model chemistries W1, CBS-APNO, and CBS-QB3 for the same test set are ±0.23 mEh, ±2.37 mEh, and ±5.80 mEh, respectively. The Wes1T-(2,3)Z triples calculation time for the largest hydrocarbon in the G2/97 test set, C6H5Me+, is reduced by a factor of 25 when compared to W1. The cost-effectiveness of the Wes1T-(2,3)Z extrapolation validates the usefulness of the Wes1T-2Z and Wes1T-3Z basis sets which are now available for a more efficient extrapolation of the (T) component of any composite model chemistry.

Ranasinghe, Duminda S.; Barnes, Ericka C.

2014-05-01

126

Revisiting Chiral Extrapolation by Studying a Lattice Quark Propagator  

International Nuclear Information System (INIS)

The quark propagator in the Landau gauge is studied on the lattice, including the quenched and the unquenched results. No obvious unquenched effects are found by comparing the quenched quark propagator with the dynamical one. For the quenched and unquenched configurations, the results with different quark masses have been computed. For the quark mass function, a nonlinear chiral extrapolating behavior is found in the infrared region for both the quenched and dynamical results. (the physics of elementary particles and fields)

127

Revisiting chiral extrapolation by studying a lattice quark propagator  

International Nuclear Information System (INIS)

The quark propagator in the Landau gauge is studied on the lattice, including the quenched and the unquenched results. No obvious unquenched effects are found by comparing the quenched quark propagator with the dynamical one. For the quenched and unquenched configurations, the results with different quark masses have been computed. For the quark mass function, a nonlinear chiral extrapolating behavior is found in the infrared region for both the quenched and dynamical results. (authors)

128

Improved Richardson's extrapolation spreadsheet calculator for numerical differentiation  

Science.gov (United States)

In this paper, we have improved the limitations of our previous Richardson's extrapolation spreadsheet calculator for computing differentiations numerically. These limitations are the value of D(0,0) keyed in by users using 3-point central difference formula, and the fact that the previous spreadsheet calculator can only calculate the approximate definite differentiation up to level 4 × 4. If the function to be differentiated is complicated, calculating D(0,0) using 3-point central difference formula can be tedious as parentheses should be put in a proper order when writing the calculation command. Otherwise, the calculation command may lead to a wrong answer. In this improved Richardson's extrapolation spreadsheet calculator, we redesigned the Richardson's extrapolation spreadsheet calculator, where users are only required to give the value of x, the function to be differentiated f(x), and the step size h value without writing the command to obtain D(0,0). Consequently, the calculations will be done automatically to approximate the definite differentiation up to level 10 × 10.

Tay, Kim Gaik; Kek, Sie Long; Abdul-Kahar, Rosmila

2014-07-01

129

Continuum extrapolation of $B_K$ with staggered fermions  

CERN Document Server

We report on recent progress in the calculation of $B_K$ using HYP-smeared staggered fermions on the MILC asqtad lattices. Our main focus is on the continuum extrapolation, which is done using (up to) four different lattice spacings---$a\\approx$ 0.12, 0.09, 0.06 and 0.045 fm. Since Lattice 2010, we have reduced the statistical errors on the $a\\approx 0.09\\;$fm lattices by a factor of $\\sim 3$, and roughly doubled the size of the $a\\approx0.045\\;$fm ensemble. We find that these improvements have a very significant impact on the continuum extrapolation, with the $a\\approx 0.12\\;$fm data lying outside the range of applicability of simple functional forms. Hence we use only the three smallest lattice spacings to perform the extrapolation, finding $\\hat{B}_K = B_K(\\text{RGI}) = 0.725 \\pm 0.004(\\text{stat}) \\pm 0.038(\\text{sys}) $. This value is consistent with our published value from 2010 (based the three coarsest lattice spacings), but has smaller errors.

Lee, Weonjong; Kim, Hyung-Jin; Kim, Jangho; Kim, Kwangwoo; Yoon, Boram; Bae, Taegil; Jung, Chulwoo; Kim, Jongjeong; Sharpe, Stephen R

2011-01-01

130

Three dimensional image guided extrapolation for cone-beam CT image reconstruction  

Science.gov (United States)

In cone-beam CT the range of projection views measured for each given image voxel is spatially variant. In the corners of the image volume there is less projection data available to be used by the image reconstruction algorithm, due to data truncation in the z direction (i.e. along the scanner axis). Given the desire to increase the fraction of the voxels which may be reconstructed from a given scan there is a desire to incorporate some extrapolated data into the image reconstruction procedure. In this work one approach is described which consists of a two-pass procedure where the first pass image reconstruction is performed over a larger extent in the z direction, a non-linear transform is applied to the initial reconstruction and a forward projection is applied in order to estimate the extrapolated image data. Initial results are presented which compare the method to zeroth order extrapolation and demonstrate that improvement in the reconstruction of the corner regions with a simple numerical phantom and with anatomical phantom data from a prototype wide coverage CT system.

Nett, Brian

2014-03-01

131

Chiral extrapolation of nucleon wave function normalization constants  

Energy Technology Data Exchange (ETDEWEB)

In the framework of two-flavor covariant baryon chiral perturbation theory, we have expressed the Chernyak-Zhitnitsky, Ioffe and Dosch currents in terms of chiral fields to provide leading one-loop extrapolation formulae for the respective leading and next-to-leading twist normalization constants f{sub N}, {lambda}{sub 1} and {lambda}{sub 2}. The occurring low energy constants are fitted to data obtained from recent lattice QCD simulations in order to extract the values at the physical point.

Wein, Philipp; Schaefer, Andreas; Hemmert, Thomas [Universitaet Regensburg (Germany)

2011-07-01

132

Chiral extrapolation of nucleon wave function normalization constants  

CERN Document Server

Within the framework of two-flavor covariant baryon chiral perturbation theory we have expressed the Chernyak-Zhitnitsky, Ioffe and Dosch currents in terms of chiral fields to provide leading one-loop extrapolation formulae for the leading and next-to-leading twist normalization constants $f_N$, $\\lambda_1$ and $\\lambda_2$. Finite volume effects due to pion loops have been taken into account. The occurring low energy constants are fitted to data obtained from recent lattice QCD simulations in order to extract the values at the physical point.

Wein, Philipp; Hemmert, Thomas R; Schäfer, Andreas

2011-01-01

133

Chiral extrapolation of nucleon wave function normalization constants  

Science.gov (United States)

Within the framework of two-flavor covariant baryon chiral perturbation theory we have expressed the Chernyak-Zhitnitsky, Ioffe and Dosch currents in terms of chiral fields to provide leading one-loop extrapolation formulae for the leading and next-to-leading twist normalization constants f N , ?1 and ?2. Finite-volume effects due to pion loops have been taken into account. The occurring low-energy constants are fitted to data obtained from recent lattice QCD simulations in order to extract the values at the physical point.

Wein, P.; Bruns, P. C.; Hemmert, T. R.; Schäfer, A.

2011-11-01

134

Chiral extrapolation of nucleon wave function normalization constants  

Energy Technology Data Exchange (ETDEWEB)

Within the framework of two-flavor covariant baryon chiral perturbation theory we have expressed the Chernyak-Zhitnitsky, Ioffe and Dosch currents in terms of chiral fields to provide leading one-loop extrapolation formulae for the leading and next-to-leading twist normalization constants f{sub N}, {lambda}{sub 1} and {lambda}{sub 2}. Finite-volume effects due to pion loops have been taken into account. The occurring low-energy constants are fitted to data obtained from recent lattice QCD simulations in order to extract the values at the physical point. (orig.)

Wein, P.; Bruns, P.C.; Hemmert, T.R.; Schaefer, A. [Universitaet Regensburg, Regensburg (Germany)

2011-11-15

135

Frequency extrapolation to enhance the deconvolution of transmitted seismic waves  

International Nuclear Information System (INIS)

We investigate the enhanced deconvolution of transmitted seismic waves from distant natural sources using autoregressive extrapolation (AR) and extended time-domain deconvolution. The amplitude spectrum of deconvolved seismograms is often restricted to a reduced frequency range from the use of a water table for the deconvolution. The attenuation effects on the teleseismic seismic waves also reduce the frequency content of the data. We compare the deconvolved spectra obtained from an AR-extended deconvolution (EARD) and an extended time-domain deconvolution (ETDD) technique for teleseismic waves. For EARD, we analyse the spectral content for the deconvolved spectra to differentiate between the domains of known and unknown spectral values. A prediction error filter is used to perform the autoregressive extrapolation to estimate the unknown spectral values. This procedure is applied on 1D and 2D synthetic data to test the approach. The EARD approach is then compared with the ETDD approach which applies an extended high-pass filter to the time-domain deconvolution approach. Both the EARD and ETDD approaches for extending the effective frequency range of the deconvolution results are then compared using observed teleseismic data recorded in southern India

136

The challenge of indication extrapolation for infliximab biosimilars.  

Science.gov (United States)

A biosimilar is intended to be highly similar to a reference biologic such that any differences in quality attributes (i.e., molecular characteristics) do not affect safety or efficacy. Achieving this benchmark for biologics, especially large glycoproteins such as monoclonal antibodies, is challenging given their complex structure and manufacturing. Regulatory guidance on biosimilars issued by the U.S. Food and Drug Administration, Health Canada and European Medicines Agency indicates that, in addition to a demonstration of a high degree of similarity in quality attributes, a reduced number of nonclinical and clinical comparative studies can be sufficient for approval. Following a tiered approach, clinical studies are required to address concerns about possible clinically significant differences that remain after laboratory and nonclinical evaluations. Consequently, a critical question arises: can clinical studies that satisfy concerns regarding safety and efficacy in one condition support "indication extrapolation" to other conditions? This question will be addressed by reviewing the case of a biosimilar to infliximab that was approved recently in South Korea, Europe, and Canada for multiple indications through extrapolation. The principles discussed should also apply to biosimilars of other monoclonal antibodies that are approved to treat multiple distinct conditions. PMID:24962198

Feagan, Brian G; Choquette, Denis; Ghosh, Subrata; Gladman, Dafna D; Ho, Vincent; Meibohm, Bernd; Zou, Guangyong; Xu, Zhenhua; Shankar, Gopi; Sealey, David C; Russell, Anthony S

2014-07-01

137

Assessing ecological effects of radionuclides: data gaps and extrapolation issues  

Energy Technology Data Exchange (ETDEWEB)

By inspection of the FASSET database on radiation effects on non-human biota, one of the major difficulties in the implementation of ecological risk assessments for radioactive pollutants is found to be the lack of data for chronic low-level exposure. A critical review is provided of a number of extrapolation issues that arise in undertaking an ecological risk assessment: acute versus chronic exposure regime; radiation quality including relative biological effectiveness and radiation weighting factors; biological effects from an individual to a population level, including radiosensitivity and lifestyle variations throughout the life cycle; single radionuclide versus multi-contaminants. The specificities of the environmental situations of interest (mainly chronic low-level exposure regimes) emphasise the importance of reproductive parameters governing the demography of the population within a given ecosystem and, as a consequence, the structure and functioning of that ecosystem. As an operational conclusion to keep in mind for any site-specific risk assessment, the present state-of-the-art on extrapolation issues allows us to grade the magnitude of the uncertainties as follows: one species to another > acute to chronic = external to internal = mixture of stressors> individual to population> ecosystem structure to function.

Garnier-Laplace, Jacqueline [Institute of Radioprotection and Nuclear Safety, Laboratory of Radioecology and Ecotoxicology, Cadarache, Bldg 186, BP 3, 13115 St Paul lez Durance cedex (France); Gilek, Michael [Department of Systems Ecology, Stockholm University, S-106 91 Stockholm (Sweden); Sundell-Bergman, Synnoeve [Swedish Radiation Protection Authority, S-171 16 Stockholm (Sweden); Larsson, Carl-Magnus [Swedish Radiation Protection Authority, S-171 16 Stockholm (Sweden)

2004-12-01

138

Assessing ecological effects of radionuclides: data gaps and extrapolation issues.  

Science.gov (United States)

By inspection of the FASSET database on radiation effects on non-human biota, one of the major difficulties in the implementation of ecological risk assessments for radioactive pollutants is found to be the lack of data for chronic low-level exposure. A critical review is provided of a number of extrapolation issues that arise in undertaking an ecological risk assessment: acute versus chronic exposure regime; radiation quality including relative biological effectiveness and radiation weighting factors; biological effects from an individual to a population level, including radiosensitivity and lifestyle variations throughout the life cycle; single radionuclide versus multi-contaminants. The specificities of the environmental situations of interest (mainly chronic low-level exposure regimes) emphasise the importance of reproductive parameters governing the demography of the population within a given ecosystem and, as a consequence, the structure and functioning of that ecosystem. As an operational conclusion to keep in mind for any site-specific risk assessment, the present state-of-the-art on extrapolation issues allows us to grade the magnitude of the uncertainties as follows: one species to another > acute to chronic = external to internal = mixture of stressors > individual to population > ecosystem structure to function. PMID:15700703

Garnier-Laplace, Jacqueline; Gilek, Michael; Sundell-Bergman, Synnöve; Larsson, Carl-Magnus

2004-12-01

139

Assessing ecological effects of radionuclides: data gaps and extrapolation issues  

International Nuclear Information System (INIS)

By inspection of the FASSET database on radiation effects on non-human biota, one of the major difficulties in the implementation of ecological risk assessments for radioactive pollutants is found to be the lack of data for chronic low-level exposure. A critical review is provided of a number of extrapolation issues that arise in undertaking an ecological risk assessment: acute versus chronic exposure regime; radiation quality including relative biological effectiveness and radiation weighting factors; biological effects from an individual to a population level, including radiosensitivity and lifestyle variations throughout the life cycle; single radionuclide versus multi-contaminants. The specificities of the environmental situations of interest (mainly chronic low-level exposure regimes) emphasise the importance of reproductive parameters governing the demography of the population within a given ecosystem and, as a consequence, the structure and functioning of that ecosystem. As an operational conclusion to keep in mind for any site-specific risk assessment, the present state-of-the-art on extrapolation issues allows us to grade the magnitude of the uncertainties as follows: one species to another > acute to chronic = external to internal = mixture of stressors> individual to population> ecosystem structure to function

140

National pattern for the realization of the unit of the dose speed absorbed in air for beta radiation. (Method: Ionometer, cavity of Bragg-Gray implemented in an extrapolation chamber with electrodes of variable separation, exposed to a field of beta radiation of {sup 90}Sr/{sup 90}Y); Patron Nacional para la realizacion de la unidad de la rapidez de dosis absorbida en aire para radiacion beta. (Metodo: Ionometrico, cavidad de Bragg-Gray implementada en una camara de extrapolacion con electrodos de separacion variable, expuesta a un campo de radiacion beta de {sup 90}Sr/{sup 90}Y)  

Energy Technology Data Exchange (ETDEWEB)

From the year of 1987 the Department of Metrology of the ININ, in their Secondary Laboratory of Calibration Dosimetric, has a patron group of sources of radiation beta and an extrapolation chamber of electrodes of variable separation.Their objective is to carry out of the unit of the dose speed absorbed in air for radiation beta. It uses the ionometric method, cavity Bragg-Gray in the extrapolation chamber with which it counts. The services that offers are: i) it Calibration : Radioactive Fuentes of radiation beta, isotopes: {sup 90}Sr/{sup 90}Y; Ophthalmic applicators {sup 9}0{sup S}r/{sup 90}Y; Instruments for detection of beta radiation with to the radiological protection: Ionization chambers, Geiger-Muller, etc.; Personal Dosemeters. ii) Irradiation with beta radiation of materials to the investigation. (Author)

Alvarez R, M. T.; Morales P, J. R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2001-01-15

 
 
 
 
141

3D Drop Size Distribution Extrapolation Algorithm Using a Single Disdrometer  

Science.gov (United States)

Determining the Z-R relationship (where Z is the radar reflectivity factor and R is rainfall rate) from disdrometer data has been and is a common goal of cloud physicists and radar meteorology researchers. The usefulness of this quantity has traditionally been limited since radar represents a volume measurement, while a disdrometer corresponds to a point measurement. To solve that problem, a 3D-DSD (drop-size distribution) method of determining an equivalent 3D Z-R was developed at the University of Central Florida and tested at the Kennedy Space Center, FL. Unfortunately, that method required a minimum of three disdrometers clustered together within a microscale network (.1-km separation). Since most commercial disdrometers used by the radar meteorology/cloud physics community are high-cost instruments, three disdrometers located within a microscale area is generally not a practical strategy due to the limitations of these kinds of research budgets. A relatively simple modification to the 3D-DSD algorithm provides an estimate of the 3D-DSD and therefore, a 3D Z-R measurement using a single disdrometer. The basis of the horizontal extrapolation is mass conservation of a drop size increment, employing the mass conservation equation. For vertical extrapolation, convolution of a drop size increment using raindrop terminal velocity is used. Together, these two independent extrapolation techniques provide a complete 3DDSD estimate in a volume around and above a single disdrometer. The estimation error is lowest along a vertical plane intersecting the disdrometer position in the direction of wind advection. This work demonstrates that multiple sensors are not required for successful implementation of the 3D interpolation/extrapolation algorithm. This is a great benefit since it is seldom that multiple sensors in the required spatial arrangement are available for this type of analysis. The original software (developed at the University of Central Florida, 1998.- 2000) has also been modified to read standardized disdrometer data format (Joss-Waldvogel format). Other modifications to the software involve accounting for vertical ambient wind motion, as well as evaporation of the raindrop during its flight time.

Lane, John

2012-01-01

142

UFOs in the LHC: Observations, studies and extrapolations  

CERN Document Server

Unidentified falling objects (UFOs) are potentially a major luminosity limitation for nominal LHC operation. They are presumably micrometer sized dust particles which lead to fast beam losses when they interact with the beam. With large-scale increases and optimizations of the beam loss monitor (BLM) thresholds, their impact on LHC availability was mitigated from mid 2011 onwards. For higher beam energy and lower magnet quench limits, the problem is expected to be considerably worse, though. In 2011/12, the diagnostics for UFO events were significantly improved: dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theoretical studies. The state of knowledge, extrapolations for nominal LHC operation and mitigation strategies are presented

Baer, T; Cerutti, F; Ferrari, A; Garrel, N; Goddard, B; Holzer, EB; Jackson, S; Lechner, A; Mertens, V; Misiowiec, M; Nebot del Busto, E; Nordt, A; Uythoven, J; Vlachoudis, V; Wenninger, J; Zamantzas, C; Zimmermann, F; Fuster, N

2012-01-01

143

A new clinical scintillation camera with pulse tail extrapolation electronics  

International Nuclear Information System (INIS)

This paper reports the performance of a new scintillation camera, designed for high event rate capability, evaluated. The system consisted of a 400 mm field-of-view NaI(Tl) camera with 61 photomultiplier tubes and modified Starcam electronics. A significant feature of the system was circuitry for performing pulse tail extrapolation and separation of individual pulses involved in pulse pile-up events. System deadtime, flood field uniformity, energy resolution, linearity, spatial resolution bar phantom image quality and misplaced events were evaluated for count rates up to 200 kcps in a 20% photopeak window. The authors' results indicate that this camera design does not compromise image quality at normal clinical count rates and at higher event rates can provide better image quality and increased sensitivity over many Anger cameras currently employed in nuclear medicine

144

2D interpolation and extrapolation of discrete magnetic measurements with toroidal harmonics for equilibrium reconstruction in a tokamak  

Science.gov (United States)

We present a method based on the use of toroidal harmonics and on a modelization of the poloidal field coils and divertor coils for the 2D interpolation and extrapolation of discrete magnetic measurements in a tokamak. The method is generic and can be used to provide the Cauchy boundary conditions needed as input by a fixed domain equilibrium reconstruction code like Equinox (Blum et al 2012 J. Comput. Phys. 231 960–80). It can also be used to extrapolate the magnetic measurements in order to compute the plasma boundary itself. The proposed method and algorithm are detailed in this paper and results from numerous numerical experiments are presented. The method is foreseen to be used in the real-time plasma control loop on the WEST tokamak (Bucalossi et al 2011 Fusion Eng. Des. 86 684–8).

Faugeras, Blaise; Blum, Jacques; Boulbe, Cedric; Moreau, Philippe; Nardon, Eric

2014-11-01

145

Characterization of an extrapolation chamber as a primary standard dosimeter for beta radiation  

Energy Technology Data Exchange (ETDEWEB)

In beta or electron radiation fields, operational dose equivalent quantities, based on absorbed dose in tissue, are used for radiation protection of the workers. Low penetration and high scattering in matter are characteristics of beta radiation that make its dosimetry more complex. Reliable measurements of absorbed dose in tissue must be traceable to an extrapolation chamber, which is the only primary standard dosimeter available for beta radiation. This ionization chamber uses the extrapolation to zero volume as the method of measurement of absorbed doses in 0.07 mm of tissue, D{sub T}(0.07); its requires the determination of correction factors related to influences from the detector itself and from the radiation field geometry. In this work, a 23392 model PTW extrapolation chamber was characterized by determining its collector electrode area, its true-null depth and the influence in its response of temperature, humidity and chamber depth. Values of the true-null depth were 0.46±0.04 mm and 0.40±0.04 mm for {sup 90}Sr/{sup 90}Y and {sup 85}Kr beta field sources, respectively. Corrections of the chamber ionization current, according to the ideal gas law significantly reduced the high influence of temperature; air humidity influence showed to be negligible within the 50% to 70% range. The high dependence of the chamber response with its volume addressed the need to determine accurately its true-null depth. These results are to be used as appropriate corrections for accurate absorbed dose in tissue determination. (author)

Reynaldo, S.R.; Benavente, J.A.; Silva, T.A. da, E-mail: sirr@cdtn.br, E-mail: silvata@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2013-08-15

146

Extrapolation from animals to the human for the retention of radiothallium in the blood  

International Nuclear Information System (INIS)

The extrapolation of tissue distribution data from animal to human has implications in the clinical application of new radiopharmaceuticals, in studies of biodistribution and biokinetics, and in estimation of radiation absorbed dose. The extrapolative method described in this study is based on the assumption that the mechanism of tissue distribution of a radionuclide in different mammalian species is similar. This assumption implies that the fractional distribution function, ?/sub h/(t), of a radionuclide in a specific tissue of one species is related to the corresponding fractional distribution function in any other species by linear transformations in the activity and time variables. Hence, the successful application of the extrapolative technique requires determining a reference ?/sub h/(t) based on a conveniently studied species and finding the relationships between the factors of the transformations and one or more measurable species-dependent parameters. To test this approach, data for retention of T1-201 in the blood of several species were used. Detailed biokinetic data in mice, collected in our laboratory, were used to determine the reference ?/sub h/(t) mouse. Data for other species were extracted from the literature and compared with ?/sub h/(t) mouse to determine the transformation factors, using the least squares fitting technique. These factors appear, on the basis of the data available, to be power functions of body weight. Retention of activity in blood was chosen as a test of the theory because data have been published for several nonhuman species as well as verifying values for the human

147

Image extrapolation for photo stitching using nonlocal patch-based inpainting  

Science.gov (United States)

Image alignment and mosaicing are usually performed on a set of overlapping images, using features in the area of overlap for seamless stitching. In many cases such images have different size and shape. So we need to crop panoramas or to use image extrapolation for them. This paper focuses on novel image inpainting method based on modified exemplar-based technique. The basic idea is to find an example (patch) from an image using local binary patterns, and replacing non-existed (`lost') data with it. We propose to use multiple criteria for a patch similarity search since often in practice existed exemplar-based methods produce unsatisfactory results. The criteria for searching the best matching uses several terms, including Euclidean metric for pixel brightness and Chi-squared histogram matching distance for local binary patterns. A combined use of textural geometric characteristics together with color information allows to get more informative description of the patches. In particular, we show how to apply this strategy for image extrapolation for photo stitching. Several examples considered in this paper show the effectiveness of the proposed approach on several test images.

Voronin, V. V.; Marchuk, V. I.; Sherstobitov, A. I.; Semenischev, E. A.; Agaian, S.; Egiazarian, K.

2014-05-01

148

Extrapolation of extreme response for different mooring line systems of floating wave energy converters  

DEFF Research Database (Denmark)

Mooring systems for floating wave energy converters (WECs) are a major cost driver. Failure of mooring systems often occurs due to extreme loads. This paper introduces an extrapolation method for extreme response which accounts for the control system of a WEC that controls the loads onto the structure and the harvested power of the device as well as the fact that extreme loads may occur during operation and not at extreme wave states when the device is in storm protection mode. The extrapolation method is based on shortterm load time series and applied to a case study where up-scaled surge load measurements from lab-scaled WEPTOS WEC are taken. Different catenary anchor leg mooring (CALM) systems as well as single anchor legmooring (SALM)mooring systemsare implemented for a dynamic simulation with different number of mooring lines. Extreme tension loads with a return period of 50 years are assessed for the hawser as well as at the different mooring lines. Furthermore, the extreme load impact given failure of one mooring line is assessed and compared with extreme loads given no system failure.

Ambühl, Simon; Sterndorff, Martin

2014-01-01

149

Vector Extrapolation-Based Acceleration of Regularized Richardson Lucy Image Deblurring  

Science.gov (United States)

Confocal fluorescence microscopy has become an important tool in biological and medical sciences for imaging thin specimen, even living ones. Due to out-of-focus blurring and noise the acquired images are degraded and thus it is necessary to restore them. One of the most popular methods is an iterative Richardson-Lucy algorithm with total variation regularization. This algorithm while improving the image quality is converging slowly whereas with a constantly increasing amount of image data fast methods are required. In this paper, we present an accelerated version of the algorithm and investigate the achieved speed up. The acceleration method is based on a vector extrapolation technique and avoids a computational intensive evaluation of the underlying cost function. To evaluate the acceleration two synthetic test images are used. The accelerated algorithm reaches an acceptable result within 30% to 40% less computational time.

Remmele, Steffen; Hesser, Jürgen

150

Extrapolation from animals to the human for the retention of radiothallium in the blood  

International Nuclear Information System (INIS)

The extrapolation of tissue distribution data from animal to human has implications in the clinical application of new radiopharmaceuticals, in studies of biodistribution and biokinetics, and in estimation of radiation absorbed dose. The extrapolative method described in this study is based on the assumption that the mechanism of tissue distribution of a radionuclide in different mammalian species is similar. This assumption implies that the fractional distribution function, ?/sub h/(t), of a radionuclide in a specific tissue of one species is related to the corresponding fractional distribution function in any other species by linear transformations in the activity and time variables. To test this approach, data for retention of T1-201 in the blood of several species were used. Detailed biokinetic data in mice, collected in our laboratory, were used to determine the reference ?/sub h/(t)/sub mouse/. Data for other species were extracted from the literature and compared with ?/sub h/(t)/sub mouse/ to determine the transformation factors, using the least squares fitting technique. These factors appear, on the basis of the data available, to be power functions of body weight. Retention of activity in blood was chosen as a test of the theory because data have been published for several nonhuman species as well as verifying values for the human

151

Dose measurement in heterogeneous phantoms with an extrapolation chamber  

Science.gov (United States)

A hybrid phantom-embedded extrapolation chamber (PEEC) made of Solid Water(TM) and bone-equivalent material was used for determining absolute dose in a bone-equivalent phantom irradiated with clinical radiation beams (cobalt-60 gamma rays; 6 and 18 MV x-rays; and 9 and 15 MeV electrons). The dose was determined with the Spencer-Attix cavity theory, using ionization gradient measurements and an indirect determination of the chamber air-mass through measurements of chamber capacitance. The air gaps used were between 2 and 3 mm and the sensitive air volume of the extrapolation chamber was remotely controlled through the motion of the motorized piston with a precision of +/-0.0025 mm. The collected charge was corrected for ionic recombination and diffusion in the chamber air volume following the standard two-voltage technique. Due to the hybrid chamber design, correction factors accounting for scatter deficit and electrode composition were determined and applied in the dose equation to obtain dose data for the equivalent homogeneous bone phantom. Correction factors for graphite electrodes were calculated with Monte Carlo techniques and the calculated results were verified through relative air cavity dose measurements for three different polarizing electrode materials: graphite, steel, and brass in conjunction with a graphite collecting electrode. Scatter deficit, due mainly to loss of lateral scatter in the hybrid chamber, reduces the dose to the air cavity in the hybrid PEEC in comparison with full bone PEEC from 0.7 to ˜2% depending on beam quality and energy. In megavoltage photon and electron beams, graphite electrodes do not affect the dose measurement in the Solid Water(TM) PEEC but decrease the cavity dose by up to 5% in the bone-equivalent PEEC even for very thin graphite electrodes (<0.0025 cm). The collecting electrode material in comparison with the polarizing electrode material has a larger effect on the electrode correction factor; the thickness of thin electrodes, on the other hand, has a negligible effect on dose determination. The uncalibrated hybrid PEEC is an accurate and absolute device for measuring the dose directly in bone material in conjunction with appropriate correction factors determined with Monte Carlo techniques.

Deblois, Francois

152

Extrapolation procedures for calculating high-temperature Gibbs free energies of aqueous electrolytes  

International Nuclear Information System (INIS)

Methods for calculating high-temperature Gibbs free energies of mononuclear cations and anions from room-temperature data are reviewed. Emphasis is given to species required for oxide solubility calculations relevant to mass transport situations in the nuclear industry. Free energies predicted by each method are compared with selected values calculated from recently reported solubility studies and other literature data. Values for monatomic ions estimated using the assumption anti Csub(p)0(T)=anti Csub(p)0(298) agree best with experiment to 423 K. From 423 to 523 K, free energies from an electrostatic model for ion hydration are more accurate. Extrapolations for hydrolysed species are limited by a lack of room-temperature entropy data and expressions for estimating these entropies are discussed. (author)

153

Measurement of fatty acid oxidation: validation of isotopic equilibrium extrapolation  

International Nuclear Information System (INIS)

Measurement of whole body substrate oxidation requires prolonged isotope infusion to attain plateau specific activity (SA) of expired CO2. We have investigated in 13 hospitalized patients a technique whereby plateau 14CO2 SA is extrapolated using computer curve fitting based upon the early exponential rise. A primed-constant infusion of albumin-bound 1-14C-palmitate was continued for 260 minutes with isotope priming of the secondary bicarbonate pool at 70 minutes. Plasma free fatty acid (FFA) SA reached steady state by 40 minutes and was 91% +/- 4% (SE) of values obtained at 190 to 260 minutes. At 70 minutes 14CO2 SA reached only 44% +/- 1% of the 190 to 260 minute values, which were consistently at plateau. The predicted steady state 14CO2 SA from the 40 to 70 minute curves and the FFA oxidation rates calculated from those values were 94% +/- 2% and 102% +/- 4%, respectively, of values measured at steady state (190 to 260 minutes). The relationship between predicted and measured values approximated the line of identity for 14CO2 SA (y = 0.90x + 0.14, r = .98, P less than .001) and FFA oxidation (y = 1.02x, r = .98, P less than .001). The results suggest that FFA oxidation can be accurately calculated using a short infusion of labeled FFA without bicarbonate pool priming, thus avoiding overpriming or underpriming and possibly allowing multiple studies and dimiossibly allowing multiple studies and diminished radioisotope exposure

154

Chiral Extrapolations and the Covariant Small Scale Expansion  

CERN Document Server

We calculate the nucleon and the delta mass to fourth order in a covariant formulation of the small scale expansion. We analyze lattice data from the MILC collaboration and demonstrate that the available lattice data combined with our knowledge of the physical values for the nucleon and delta masses lead to consistent chiral extrapolation functions for both observables up to fairly large pion masses. This holds in particular for very recent data on the delta mass from the QCDSF collaboration. The resulting pion-nucleon sigma term is sigma_{piN} = 48.9 MeV. This first quantitative analysis of the quark-mass dependence of the structure of the Delta(1232) in full QCD within chiral effective field theory suggests that (the real part of) the nucleon-delta mass-splitting in the chiral limit, Delta_0 = 0.33 GeV, is slightly larger than at the physical point. Further analysis of simultaneous fits to nucleon and delta lattice data are needed for a precision determination of the properties of the first excited state of...

Bernard, V; Meißner, Ulf G; Hemmert, Thomas R.; Mei{\\ss}ner, Ulf-G.

2005-01-01

155

Characterization and application of two extrapolation chambers in standard X radiation beams  

International Nuclear Information System (INIS)

The extrapolation chambers are ionization chambers with variable volume, and they are mainly utilized as beta radiation detectors. In this work two extrapolation chambers were characterized, a commercial PTW extrapolation chamber and another extrapolation chamber developed at the Calibration Laboratory of IPEN, for application as reference systems in mammography, conventional diagnostic radiology and radiotherapy beams. The results obtained from the characterization tests of the chamber response: leakage current, short- and medium terms stability, determination of the saturation currents and the ion collection efficiencies, angular and energy dependence, show that these extrapolation chambers may be utilized for low-energy X radiation beam dosimetry. The transmission factors in tissue and the calibration factors were also determined for all cited radiation qualities. Finally, a procedure was established for calibration of radiation detectors in standard X radiation beams, using the extrapolation chambers. (author)

156

Epistemological considerations in the extrapolation of metabolic data from non-humans to humans  

International Nuclear Information System (INIS)

The rationale underlying interspecies extrapolation of metabolic data has been based primarily on pragmatic concerns. Little attention has been given to the extent to which such extrapolations have a firm epistemological basis. The strength of this approach for model-free (purely empirical) extrapolation and for extrapolation involving a variety of theoretical constructs is examined in this paper. An attempt is made to provide some understanding of the degree of confidence that can be placed in the extrapolation of metabolic data from one species to another. Published results for a wide variety of radionuclides are analyzed and the importance of these results to the field of nuclear medicine is explored. Problems inherent in the logic of extrapolation are then delineated in view of these historical data

157

The extrapolation of short term observation to time periods for isolation of long lived radioactive wastes (India)  

International Nuclear Information System (INIS)

The work presented covers different parts of a repository system such as near and far field aspects. Investigations are reported for the degradation of HLW glass, for the corrosion of container materials, for changes of geochemical environment in geological repositories, and for the thermo-mechanical behaviour of granitic host rock. Extrapolation methods are developed and applied for temperature and stress development in the host rock and for the radionuclide transport through a fractured system. (author)

158

Extrapolation from , vector-valued inequalities and applications in the Schrödinger settings  

Science.gov (United States)

In this paper, we generalize the A ? extrapolation theorem ( Cruz-Uribe-Martell-Pérez, Extrapolation from A ? weights and applications, J. Funct. Anal. 213 (2004), 412-439) and the A p extrapolation theorem of Rubio de Francia to Schrödinger settings. In addition, we also establish weighted vector-valued inequalities for Schrödinger-type maximal operators by using weights belonging to which includes A p . As applications, we establish weighted vector-valued inequalities for some Schrödinger-type operators.

Tang, Lin

2014-04-01

159

Constraining 3D Magnetic Field Extrapolations Using The Twin Perspectives of STEREO  

CERN Document Server

The 3D magnetic topology of a solar active region (NOAA 10956) was reconstructed using a linear force-free field extrapolation constrained using the twin perspectives of \\emph{STEREO}. A set of coronal field configurations was initially generated from extrapolations of the photospheric magnetic field observed by the Michelson Doppler Imager (MDI) on \\emph{SOHO}. Using an EUV intensity-based cost function, the extrapolated field lines that were most consistent with 171\\AA\\ passband images from the Extreme UltraViolet Imager (EUVI) on \\emph{STEREO} were identified. This facilitated quantitative constraints to be placed on the twist ($\\alpha$) of the extrapolated field lines, where $\

Conlon, Paul A

2010-01-01

160

A Visual Basic Program to Generate Sediment Grain-Size Statistics and Extrapolate Particle Distributions  

Science.gov (United States)

Methods that describe and summarize grain-size distributions are important to geologists because of the large amount of information contained in textural data sets. Therefore, to facilitate reduction of sedimentologic data, we have written a computer program (GSSTAT) to generate grain-size statistics and extrapolate particle distributions. Our program is written in Microsoft Visual Basic 6.0, runs on Windows 95/98/ME/NT/2000/XP computers, provides a window to facilitate execution, and allows users to select options with mouse-click events or through interactive dialogue boxes. The program permits users to select output in either inclusive graphics or moment statistics, to extrapolate distributions to the colloidal-clay boundary by three methods, and to convert between frequency and cumulative frequency percentages. Detailed documentation is available within the program. Input files to the program must be comma-delimited ASCII text and have 20 fields that include: sample identifier, latitude, longitude, and the frequency or cumulative frequency percentages of the whole-phi fractions from 11 phi through -5 phi. Individual fields may be left blank, but the sum of the phi fractions must total 100% (+/- 0.2%). The program expects the first line of the input file to be a header showing attribute names; no embedded commas are allowed in any of the fields. Error messages warn the user of potential problems. The program generates an output file in the requested destination directory and allows the user to view results in a display window to determine the occurrence of errors. The output file has a header for its first line, but now has 34 fields; the original descriptor fields plus percentages of gravel, sand, silt and clay, statistics, classification, verbal descriptions, frequency or cumulative frequency percentages of the whole- phi fractions from 13 phi through -5 phi, and a field for error messages. If the user has selected extrapolation, the two additional phi-fraction fields will be populated with data. The software with the necessary support files, installation instructions, and documentation is available free of charge from the USGS.

Poppe, L. J.; Eliason, A. E.; Hastings, M. E.

2004-05-01

 
 
 
 
161

Multi-threaded adaptive extrapolation procedure for Feynman loop integrals in the physical region  

International Nuclear Information System (INIS)

Feynman loop integrals appear in higher order corrections of interaction cross section calculations in perturbative quantum field theory. The integrals are computationally intensive especially in view of singularities which may occur within the integration domain. For the treatment of threshold and infrared singularities we developed techniques using iterated (repeated) adaptive integration and extrapolation. In this paper we describe a shared memory parallelization and its application to one- and two-loop problems, by multi-threading in the outer integrations of the iterated integral. The implementation is layered over OpenMP and retains the adaptive procedure of the sequential method exactly. We give performance results for loop integrals associated with various types of diagrams including one-loop box, pentagon, two-loop self-energy and two-loop vertex diagrams

162

Quark number density at imaginary chemical potential and its extrapolation to large real chemical potential by the effective model  

CERN Document Server

We evaluate quark number densities at imaginary chemical potential by lattice QCD with clover-improved two-flavor Wilson fermion. The quark number densities are extrapolated to the small real chemical potential region by assuming some function forms. The extrapolated quark number densities are consistent with those calculated at real chemical potential with the Taylor expansion method for the reweighting factors. In order to study the large real chemical potential region, we use the two-phase model consisting of the quantum hadrodynamics model for the hadron phase and the entanglement-PNJL model for the quark phase. The quantum hadrodynamics model is constructed to reproduce nuclear saturation properties, while the entanglement-PNJL model reproduces well lattice QCD data for the order parameters such as the Polyakov loop, the thermodynamic quantities and the screening masses. Then, we calculate the mass-radius relation of neutron stars and explore the hadron-quark phase transition with the two-phase model.

Takahashi, Junichi; Ishii, Masahiro; Kouno, Hiroaki; Yahiro, Masanobu

2014-01-01

163

CT image construction of a totally deflated lung using deformable model extrapolation  

International Nuclear Information System (INIS)

Purpose: A novel technique is proposed to construct CT image of a totally deflated lung from a free-breathing 4D-CT image sequence acquired preoperatively. Such a constructed CT image is very useful in performing tumor ablative procedures such as lung brachytherapy. Tumor ablative procedures are frequently performed while the lung is totally deflated. Deflating the lung during such procedures renders preoperative images ineffective for targeting the tumor. Furthermore, the problem cannot be solved using intraoperative ultrasound (U.S.) images because U.S. images are very sensitive to small residual amount of air remaining in the deflated lung. One possible solution to address these issues is to register high quality preoperative CT images of the deflated lung with their corresponding low quality intraoperative U.S. images. However, given that such preoperative images correspond to an inflated lung, such CT images need to be processed to construct CT images pertaining to the lung's deflated state. Methods: To obtain the CT images of deflated lung, we present a novel image construction technique using extrapolated deformable registration to predict the deformation the lung undergoes during full deflation. The proposed construction technique involves estimating the lung's air volume in each preoperative image automatically in order to track the respiration phase of each 4D-CT image throughout a respiratory cycle; i.e., the technique does not need any external marker to fque does not need any external marker to form a respiratory signal in the process of curve fitting and extrapolation. The extrapolated deformation field is then applied on a preoperative reference image in order to construct the totally deflated lung's CT image. The technique was evaluated experimentally using ex vivo porcine lung. Results: The ex vivo lung experiments led to very encouraging results. In comparison with the CT image of the deflated lung we acquired for the purpose of validation, the constructed CT image was very similar. The intensity mean absolute difference between these two images was calculated to be at 1%. Tumor center as well as a number of anatomical fiducial markers were traced in different corresponding slices of the two images. The average misalignment obtained for the constructed CT image was (0.64, 0.39, 0.11) mm, which indicates a very desirable accuracy for lung brachytherapy applications. Conclusions: The image construction accuracy obtained in this research is suitable for intraoperative tasks; e.g., tumor localization and fusing with real time navigation data in lung brachytherapy. These applications involve image registration with intraoperative U.S. images in order to enhance their poor quality. The proposed technique is also useful for preoperative tasks such as planning of lung brachytherapy treatment.

164

Fuel cycle design for ITER and its extrapolation to DEMO  

International Nuclear Information System (INIS)

ITER is the first fusion device that continuously processes DT plasma exhaust and supplies recycled fuel in a closed loop. All the tritium and deuterium in the exhaust are recovered, purified and returned to the tokamak with minimal delay, so that extended burn can be sustained with limited inventory. To maintain the safety of the entire facility, plant scale detritiation systems will also continuously run to remove tritium from the effluents at the maximum efficiency. In this entire tritium plant system, extremely high decontamination factor, that is the ratio of the tritium loss to the processing flow rate, is required for fuel economy and minimized tritium emissions, and the system design based on the state-of-the-art technology is expected to satisfy all the requirements without significant technical challenges. Considerable part of the fusion tritium system will be verified with ITER and its decades of operation experiences. Toward the DEMO plant that will actually generate energy and operate its closed fuel cycle, breeding blanket and power train that caries high temperature and pressure media from the fusion device to the generation system will be the major addition. For the tritium confinement, safety and environmental emission, particularly blanket, its coolant, and generation systems such as heat exchanger, steam generator and turbine will be the critical systems, because the tritium permeation from the breeder and handling large amount of high temperature, andling large amount of high temperature, high pressure coolant will be further more difficult than that required for ITER. Detritiation of solid waste such as used blanket and divertor will be another issue for both tritium economy and safety. Unlike in the case of ITER that is regarded as experimental facility, DEMO will be expected to demonstrate the safety, reliability and social acceptance issue, even if economical feature is excluded. Fuel and environmental issue to be tested in the DEMO will determine the viability of the fusion as a future energy source. Some of the subjects cannot be expected to be within the extrapolation of ITER technology and require long term efforts paralleling ITER

165

Dosimetry of planar and punctiform beta sources using an automated extrapolation chamber and radiochromic dye films  

International Nuclear Information System (INIS)

A Loevinger extrapolation chamber has been automated and used to determine detailed dose distributions around beta emitting sources of varied geometry. The absolute dose estimates provided by the extrapolation chamber have been compared with those obtained from radiochromic dye film dosemeters. For large area planar sources, extrapolation chamber estimates obtained by conventional linear extrapolation of the ionisation current/electrode spacing characteristic are in reasonable agreement with the radiochromic film values. The shape of the curve for punctiform sources, however, indicates that significant curvature may still be present at the smallest practically attainable electrode separations. In such situations non-linear extrapolation of the current/spacing curve appears to provide estimates which are in better agreement with those obtained using radiochromic film. This is in accord with the predictions of a simple theoretical model for an idealised point source. (author)

166

Direct extrapolation of radial profile data to a self-ignited fusion reactor based on the gyro-Bohm model  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer The DPE method predicts temperature and density profiles in a fusion reactor. Black-Right-Pointing-Pointer This method is based on the gyro-Bohm type parameter dependence. Black-Right-Pointing-Pointer The size of fusion reactor is determined to fulfill the power balance. Black-Right-Pointing-Pointer The reactor size is proportional to a factor and -4/3 power of the magnetic field. Black-Right-Pointing-Pointer This factor can be a measure of plasma performance like the fusion triple product. - Abstract: A new method named direct profile extrapolation (DPE) has been developed to estimate the radial profiles of temperature and density in a fusion reactor. This method directly extrapolates the radial profiles observed in present experiments to the fusion reactor condition assuming gyro-Bohm type parameter dependence. The magnetohydrodynamic equilibrium that fits the experimental profile data is used to determine the plasma volume. Four enhancement factors for the magnetic field strength, the density, the plasma beta, and the energy confinement are assumed. Then, the plasma size is determined so as to fulfill the power balance in the reactor plasma. The plasma performance can be measured by an index, C{sub exp}, introduced in the DPE method. The minimum magnetic stored energy of the fusion reactor to achieve self-ignition is shown to be proportional to the cube of C{sub exp} and inversely proportional to the square of magnetic field strength. Using this method, the design window of a self-ignited fusion reactor that can be extrapolated from recent experimental results in the Large Helical Device (LHD) is considered. Also discussed is how large an enhancement is needed for the LHD experiment to ensure the helical reactor design of FFHR2m2.

Miyazawa, J., E-mail: miyazawa@LHD.nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Goto, T.; Morisaki, T.; Goto, M.; Sakamoto, R.; Motojima, G.; Peterson, B.J.; Suzuki, C.; Ida, K.; Yamada, H.; Sagara, A. [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan)

2011-12-15

167

Design and construction of an interface system for the extrapolation chamber from the beta secondary standard  

International Nuclear Information System (INIS)

The Interface System for the Extrapolation Chamber (SICE) contains several devices handled by a personal computer (PC), it is able to get the required data to calculate the absorbed dose due to Beta radiation. The main functions of the system are: a) Measures the ionization current or charge stored in the extrapolation chamber. b) Adjusts the distance between the plates of the extrapolation chamber automatically. c) Adjust the bias voltage of the extrapolation chamber automatically. d) Acquires the data of the temperature, atmospheric pressure, relative humidity of the environment and the voltage applied between the plates of the extrapolation chamber. e) Calculates the effective area of the plates of the extrapolation chamber and the real distance between them. f) Stores all the obtained information in hard disk or diskette. A comparison between the desired distance and the distance in the dial of the extrapolation chamber, show us that the resolution of the system is of 20 ?m. The voltage can be changed between -399.9 V and +399.9 V with an error of less the 3 % with a resolution of 0.1 V. These uncertainties are between the accepted limits to be used in the determination of the absolute absorbed dose due to beta radiation. (Author)

168

CONSTRAINING THREE-DIMENSIONAL MAGNETIC FIELD EXTRAPOLATIONS USING THE TWIN PERSPECTIVES OF STEREO  

International Nuclear Information System (INIS)

The three-dimensional magnetic topology of a solar active region (NOAA 10956) was reconstructed using a linear force-free field extrapolation constrained using the twin perspectives of STEREO. A set of coronal field configurations was initially generated from extrapolations of the photospheric magnetic field observed by the Michelson Doppler Imager on SOHO. Using an EUV intensity-based cost function, the extrapolated field lines that were most consistent with 171 A passband images from the Extreme UltraViolet Imager on STEREO were identified. This facilitated quantitative constraints to be placed on the twist (?) of the extrapolated field lines, where ? x B = ?B. Using the constrained values of ?, the evolution in time of twist, connectivity, and magnetic energy were then studied. A flux emergence event was found to result in significant changes in the magnetic topology and total magnetic energy of the region.

169

Melting of "non-magic" argon clusters and extrapolation to the bulk limit  

Science.gov (United States)

The melting of argon clusters ArN is investigated by applying a parallel-tempering Monte Carlo algorithm for all cluster sizes in the range from 55 to 309 atoms. Extrapolation to the bulk gives a melting temperature of 85.9 K in good agreement with the previous value of 88.9 K using only Mackay icosahedral clusters for the extrapolation [E. Pahl, F. Calvo, L. Ko?i, and P. Schwerdtfeger, "Accurate melting temperatures for neon and argon from ab initio Monte Carlo simulations," Angew. Chem., Int. Ed. 47, 8207 (2008)]. Our results for argon demonstrate that for the extrapolation to the bulk one does not have to restrict to magic number cluster sizes in order to obtain good estimates for the bulk melting temperature. However, the extrapolation to the bulk remains a problem, especially for the systematic selection of suitable cluster sizes.

Senn, Florian; Wiebke, Jonas; Schumann, Ole; Gohr, Sebastian; Schwerdtfeger, Peter; Pahl, Elke

2014-01-01

170

Melting of “non-magic” argon clusters and extrapolation to the bulk limit  

International Nuclear Information System (INIS)

The melting of argon clusters ArN is investigated by applying a parallel-tempering Monte Carlo algorithm for all cluster sizes in the range from 55 to 309 atoms. Extrapolation to the bulk gives a melting temperature of 85.9 K in good agreement with the previous value of 88.9 K using only Mackay icosahedral clusters for the extrapolation [E. Pahl, F. Calvo, L. Ko?i, and P. Schwerdtfeger, “Accurate melting temperatures for neon and argon from ab initio Monte Carlo simulations,” Angew. Chem., Int. Ed. 47, 8207 (2008)]. Our results for argon demonstrate that for the extrapolation to the bulk one does not have to restrict to magic number cluster sizes in order to obtain good estimates for the bulk melting temperature. However, the extrapolation to the bulk remains a problem, especially for the systematic selection of suitable cluster sizes

171

Melting of “non-magic” argon clusters and extrapolation to the bulk limit  

Energy Technology Data Exchange (ETDEWEB)

The melting of argon clusters Ar{sub N} is investigated by applying a parallel-tempering Monte Carlo algorithm for all cluster sizes in the range from 55 to 309 atoms. Extrapolation to the bulk gives a melting temperature of 85.9 K in good agreement with the previous value of 88.9 K using only Mackay icosahedral clusters for the extrapolation [E. Pahl, F. Calvo, L. Ko?i, and P. Schwerdtfeger, “Accurate melting temperatures for neon and argon from ab initio Monte Carlo simulations,” Angew. Chem., Int. Ed. 47, 8207 (2008)]. Our results for argon demonstrate that for the extrapolation to the bulk one does not have to restrict to magic number cluster sizes in order to obtain good estimates for the bulk melting temperature. However, the extrapolation to the bulk remains a problem, especially for the systematic selection of suitable cluster sizes.

Senn, Florian, E-mail: f.senn@massey.ac.nz; Wiebke, Jonas; Schumann, Ole; Gohr, Sebastian; Schwerdtfeger, Peter, E-mail: p.a.schwerdtfeger@massey.ac.nz [Centre for Theoretical Chemistry and Physics, The New Zealand Institute for Advanced Study, Massey University Albany, Private Bag 102904, Auckland 0745 (New Zealand); Pahl, Elke, E-mail: e.pahl@massey.ac.nz [Centre for Theoretical Chemistry and Physics, Institute of Natural and Mathematical Sciences, Massey University Albany, Private Bag 102904, Auckland 0745 (New Zealand)

2014-01-28

172

Accuracy of basis-set extrapolation schemes for DFT-RPA correlation energies in molecular calculations  

CERN Document Server

We construct a reference benchmark set for atomic and molecular random-phase-approximation (RPA) correlation energies in a density functional theory (DFT) framework at the complete basis set limit. This set is used to evaluate the accuracy of some popular extrapolation schemes for RPA all-electron molecular calculations. The results indicate that for absolute energies accurate results, clearly outperforming raw data, are achievable with two-point extrapolation schemes based on quintuple- and sextuple-zeta basis sets. Moreover, we show that results in good agreement with the benchmark can also be also obtained by using a semiempirical extrapolation procedure based on quadruple- and quintuple-zeta basis sets. Finally, we analyze the performance of different extrapolation schemes for atomization energies.

Fabiano, E; 10.1007/s00214-012-1278-8

2013-01-01

173

Extrapolation of sparse tensor fields: application to the modeling of brain variability.  

Science.gov (United States)

Modeling the variability of brain structures is a fundamental problem in the neurosciences. In this paper, we start from a dataset of precisely delineated anatomical structures in the cerebral cortex: a set of 72 sulcal lines in each of 98 healthy human subjects. We propose an original method to compute the average sulcal curves, which constitute the mean anatomy in this context. The second order moment of the sulcal distribution is modeled as a sparse field of covariance tensors (symmetric, positive definite matrices). To extrapolate this information to the full brain, one has to overcome the limitations of the standard Euclidean matrix calculus. We propose an affine-invariant Riemannian framework to perform computations with tensors. In particular, we generalize radial basis function (RBF) interpolation and harmonic diffusion PDEs to tensor fields. As a result, we obtain a dense 3D variability map which proves to be in accordance with previously published results on smaller samples subjects. Moreover, leave one (sulcus) out tests show that our model is globally able to recover the missing information when there is a consistent neighboring variability. Last but not least, we propose innovative methods to analyze the asymmetry of brain variability. As expected, the greatest asymmetries are found in regions that includes the primary language areas. Interestingly, such an asymmetry in anatomical variance could explain why there may be greater power to detect group activation in one hemisphere than the other in fMRI studies. PMID:17354682

Fillard, Pierre; Arsigny, Vincent; Pennec, Xavier; Thompson, Paul M; Ayache, Nicholas

2005-01-01

174

Extrapolation chamber for absolute energy dose rate measurement of beta and soft x radiation  

International Nuclear Information System (INIS)

A new extrapolation chamber is described, which is used as absolute standard for the determination of the absorbed beta radiation dose. The construction simulates a semi-infinite phantom and the absorbed dose to tissue was determined in tissue equivalent material. With a new system of concentric collecting electrodes it is possible to obtain the absorbed dose at the centre of the electrodes, which is extrapolated from five values of the surface of the collecting electrodes. (Author)

175

Terahertz in-line digital holography of dragonfly hindwing: amplitude and phase reconstruction at enhanced resolution by extrapolation.  

Science.gov (United States)

We report here on terahertz (THz) digital holography on a biological specimen. A continuous-wave (CW) THz in-line holographic setup was built based on a 2.52 THz CO(2) pumped THz laser and a pyroelectric array detector. We introduced novel statistical method of obtaining true intensity values for the pyroelectric array detector's pixels. Absorption and phase-shifting images of a dragonfly's hindwing were reconstructed simultaneously from single in-line hologram. Furthermore, we applied phase retrieval routines to eliminate twin image and enhanced the resolution of the reconstructions by hologram extrapolation beyond the detector area. The finest observed features are 35 ?m width cross veins. PMID:25090537

Rong, Lu; Latychevskaia, Tatiana; Wang, Dayong; Zhou, Xun; Huang, Haochong; Li, Zeyu; Wang, Yunxin

2014-07-14

176

Do different types of dynamic extrapolation rely on the same mechanism?  

Science.gov (United States)

Observers can estimate the position of occluded moving objects, and this ability could be mediated by the oculomotor control system. However, other forms of motion cannot be tracked with pursuit eye movements. In Experiment 1, 2 kinds of motion extrapolation tasks were interleaved. In the Position extrapolation trials, participants observed a moving target that became occluded. They attempted to press a button when it arrived at the end of the occluder. In novel Accumulation extrapolation trials, they observed a matrix of Gabors with new elements appearing over time. The participants pressed when Gabors would have filled the entire matrix, had they continued accumulating at the same rate. In both tasks completion time estimates were related to presentation parameters in the same way. Moreover, there were robust intertask correlations: Participants who responded earlier in the position task also responded earlier in the accumulation task. Experiment 2 replicated these results with a third form of extrapolation. Although performance was not identical in all tasks, there were enough similarities to suggest that overlapping systems guide all forms of extrapolation. We propose that a common rate control mechanism guides extrapolation, like the velocity store in oculomotor control, but with a broader function than previously envisaged. PMID:24842064

Makin, Alexis David James; Bertamini, Marco

2014-08-01

177

Rank regularization and Bayesian inference for tensor completion and extrapolation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A novel regularizer of the PARAFAC decomposition factors capturing the tensor's rank is proposed in this paper, as the key enabler for completion of three-way data arrays with missing entries. Set in a Bayesian framework, the tensor completion method incorporates prior information to enhance its smoothing and prediction capabilities. This probabilistic approach can naturally accommodate general models for the data distribution, lending itself to various fitting criteria that...

Bazerque, Juan Andres; Mateos, Gonzalo; Giannakis, Georgios B.

2013-01-01

178

Skeletal 212Pb retention following 224Ra injection: extrapolation of animal data to adult humans  

International Nuclear Information System (INIS)

Two methods of interspecies extrapolation, one based on a correlation of skeletal 212Pb/224Ra with body weight, the other based on the mechanistic relationship between skeletal 212Pb/224Ra and reciprocal bone surface-to-volume ratio, lead to the conclusion that the retention of 212Pb in the adult human skeleton is approximately complete a few days after injection. The correlation-based method gives most probable values for 212Pb/224Ra of 1.0 and 1.1 at 2 d and 7 d after injection, compared with values of 1.05 and 1.27 expected at these same times if the retention of 212Pb were complete from the time of injection and if no 212Pb were in the injection solution. The range of values corresponding to one geometric standard error on either side of the most probable value is 0.87 to 1.21 at 2 d post-injection. With the method based on the reciprocal bone surface-to-volume ratio, the best estimate of 212Pb/224Ra at 2 d after injection is 0.88, equal to the value observed in young adult beagles. An alternative interpretation of the results of this latter method leads to the conclusion that retention is complete, with 212Pb/224Ra equal to 1.0 for a 212Pb-free injection solution and 1.1 for a solution containing 212Pb in secular equilibrium with 224Ra. This work, which uses 224Ra daughter product retention data from mice, rats and dogs following 224Ra injection, provides a scientific foundation for retention assumptions made in the calculation of mean skeletal dose for adult humans. There now appear to be few uncertainties in these latter dose values, stemming from inaccurate retention assumptions; but substantial uncertainties remain in the mean skeletal dose values for juveniles and in the endosteal tissue doses regardless of age

179

Extrapolation of Nitrogen Fertiliser Recommendation Zones for Maize in Kisii District Using Geographical Information Systems  

International Nuclear Information System (INIS)

A GIS database was established for fertiliser recommendation domains in Kisii District by using FURP fertiliser trial results, KSS soils data and MDBP climatic data. These are manipulated in ESRI's (Personal Computer Environmental Systems Research Institute) ARCINFO and ARCVIEW softwares. The extrapolations were only done for the long rains season (March- August) with three to four years data. GIS technology was used to cluster fertiliser recommendation domains as a geographical area expressed in terms of variation over space and not limited to the site of experiment where a certain agronomic or economic fertiliser recommendation was made. The extrapolation over space was found to be more representative for any recommendation, the result being digital maps describing each area in the geographical space. From the results of the extrapolations, approximately 38,255 ha of the district require zero Nitrogen (N) fertilisation while 94,330 ha requires 75 kg ha-1 Nitrogen fertilisation during the (March-August) long rains. The extrapolation was made difficult since no direct relationships could be established to occur between the available-N, % Carbon (C) or any of the other soil properties with the obtained yields. Decision rules were however developed based on % C which was the soil variable with values closest to the obtained yields. 3% organic carbon was found to be the boundary between 0 application and 75 kg-N application. GIS techniques made it possible to ation. GIS techniques made it possible to model and extrapolates the results using the available data. The extrapolations still need to be verified with more ground data from fertiliser trials. Data gaps in the soil map left some soil mapping units with no recommendations. Elevation was observed to influence yields and it should be included in future extrapolation by clustering digital elevation models with rainfall data in a spatial model at the district scale

180

EXTRAPOLATION OF THE SOLAR CORONAL MAGNETIC FIELD FROM SDO/HMI MAGNETOGRAM BY A CESE-MHD-NLFFF CODE  

International Nuclear Information System (INIS)

Due to the absence of direct measurement, the magnetic field in the solar corona is usually extrapolated from the photosphere in a numerical way. At the moment, the nonlinear force-free field (NLFFF) model dominates the physical models for field extrapolation in the low corona. Recently, we have developed a new NLFFF model with MHD relaxation to reconstruct the coronal magnetic field. This method is based on CESE-MHD model with the conservation-element/solution-element (CESE) spacetime scheme. In this paper, we report the application of the CESE-MHD-NLFFF code to Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) data with magnetograms sampled for two active regions (ARs), NOAA AR 11158 and 11283, both of which were very non-potential, producing X-class flares and eruptions. The raw magnetograms are preprocessed to remove the force and then inputted into the extrapolation code. Qualitative comparison of the results with the SDO/AIA images shows that our code can reconstruct magnetic field lines resembling the EUV-observed coronal loops. Most important structures of the ARs are reproduced excellently, like the highly sheared field lines that suspend filaments in AR 11158 and twisted flux rope which corresponds to a sigmoid in AR 11283. Quantitative assessment of the results shows that the force-free constraint is fulfilled very well in the strong-field regions but apparently not that well in the weak-field regions because of data noise and numerical gions because of data noise and numerical errors in the small currents.

 
 
 
 
181

Application of the largest Lyapunov exponent and non-linear fractal extrapolation algorithm to short-term load forecasting  

International Nuclear Information System (INIS)

Highlights: ? The maximal predictive step size is determined by the largest Lyapunov exponent. ? A proper forecasting step size is applied to load demand forecasting. ? The improved approach is validated by the actual load demand data. ? Non-linear fractal extrapolation method is compared with three forecasting models. ? Performance of the models is evaluated by three different error measures. - Abstract: Precise short-term load forecasting (STLF) plays a key role in unit commitment, maintenance and economic dispatch problems. Employing a subjective and arbitrary predictive step size is one of the most important factors causing the low forecasting accuracy. To solve this problem, the largest Lyapunov exponent is adopted to estimate the maximal predictive step size so that the step size in the forecasting is no more than this maximal one. In addition, in this paper a seldom used forecasting model, which is based on the non-linear fractal extrapolation (NLFE) algorithm, is considered to develop the accuracy of predictions. The suitability and superiority of the two solutions are illustrated through an application to real load forecasting using New South Wales electricity load data from the Australian National Electricity Market. Meanwhile, three forecasting models: the gray model, the seasonal autoregressive integrated moving average approach and the support vector machine method, which received high approval in STLF, are selected to compare with the NLFE algorithm. Comparison results also show that the NLFE model is outstanding, effective, practical and feasible.

182

Data-driven scale extrapolation: estimating yearly discharge for a large region by small sub-basins  

Science.gov (United States)

Large-scale hydrological models and land surface models are so far the only tools for assessing current and future water resources. Those models estimate discharge with large uncertainties, due to the complex interaction between climate and hydrology, the limited availability and quality of data, as well as model uncertainties. A new purely data-driven scale-extrapolation method to estimate discharge for a large region solely from selected small sub-basins, which are typically 1-2 orders of magnitude smaller than the large region, is proposed. Those small sub-basins contain sufficient information, not only on climate and land surface, but also on hydrological characteristics for the large basin. In the Baltic Sea drainage basin, best discharge estimation for the gauged area was achieved with sub-basins that cover 5% of the gauged area. There exist multiple sets of sub-basins whose climate and hydrology resemble those of the gauged area equally well. Those multiple sets estimate annual discharge for the gauged area consistently well with 6 % average error. The scale-extrapolation method is completely data-driven; therefore it does not force any modelling error into the prediction. The multiple predictions are expected to bracket the inherent variations and uncertainties of the climate and hydrology of the basin.

Gong, L.

2014-01-01

183

Chiral extrapolation of lattice data for the hyperfine splittings of heavy mesons  

International Nuclear Information System (INIS)

Full text: Hyperfine splittings between the heavy vector (D*, B*) and pseudoscalar (D, B) mesons have been calculated numerically in lattice QCD, where the pion mass (which is related to the light quark mass) is much larger than its physical value. Naive linear chiral extrapolations of the lattice data to the physical mass of the pion lead to hyperfine splittings which are smaller than experimental data. In order to extrapolate these lattice data to the physical mass of the pion more reasonably, we apply the effective chiral perturbation theory for heavy mesons, which is invariant under chiral symmetry when the light quark masses go to zero and heavy quark symmetry when the heavy quark masses go to infinity. This leads to a phenomenological functional form with three parameters to extrapolate the lattice data. It is found that the extrapolated hyperfine splittings are even smaller than those obtained using linear extrapolation. We conclude that the source of the discrepancy between lattice data for hyperfine splittings and experiment must lie in non-chiral physics

184

A Practical Approach to Coronal Magnetic Field Extrapolation Based on the Principle of Minimum Dissipation Rate  

CERN Document Server

We present a newly developed approach to solar coronal magnetic field extrapolation from vector magnetograms, based on the Principle of Minimum Dissipation Rate (MDR). The MDR system was derived from a variational problem that is more suitable for an open and externally driven system, like the solar corona. The resulting magnetic field equation is more general than force-free. Its solution can be expressed as the superposition of two linear (constant-$\\alpha$) force-free fields (LFFFs) with distinct $\\alpha$ parameters, and one potential field. Thus the original extrapolation problem is decomposed into three LFFF extrapolations, utilizing boundary data. The full MDR-based approach requires two layers of vector magnetograph measurements on solar surface, while a slightly modified practical approach only requires one. We test both approaches against 3D MHD simulation data in a finite volume. Both yield quantitatively good results. The errors in the magnetic energy estimate are within a few percents. In particul...

Hu, Q; Choudhary, D P; Büchner, J

2007-01-01

185

Comparison between the response of two extrapolation chambers in low energy X-rays  

International Nuclear Information System (INIS)

Full text: Extrapolation chambers are important metrological instruments for detection of beta radiation and low energy X-rays, since they are able to determine absolute measurements of radiations of soft penetration. These chambers are very useful, because they allow the determination of superficial doses through the variation of the air mass in its sensible volume. In this work, two extrapolation chambers were tested in order to establish which chamber presents the best response in some standard qualities of X-ray beams, radiotherapy level. For comparison, a commercial PTW extrapolation chamber model 23391 and an extrapolation chamber designed and constructed at the Radiation Metrology Laboratory of Instituto de Pesquisas Energeticas e Nucleares, were studied. The commercial chamber has a collecting electrode (40 mm diameter) and guard rings made of aluminum, and entrance window (0.025 mm thick) made of polyamide; the developed chamber presents a collecting electrode (10 mm diameter) and guard rings made of graphite, and entrance window (0,84 mg/cm2 thick) made of aluminized polyethylene terephthalate. Both chambers were positioned at 50 cm from the X-ray system focus. The ionization currents were measured at negative and positive polarities, and the mean values were considered. A Keithley 617 electrometer was utilized. The main characteristics of the extrapolation chambers, as ion collection efficiency, saturation curve, polarity effect, repeatability, long time stability, stabilization time, linearity response, extrapolation curve, energy dependency, and transmission factors were determined. The results show that both chambers present adequate responses for the verified X-ray beam qualities, confirming previous studies realized with these detectors. In conclusion, both chambers can be used for accurate measurements in low energy X-ray beams. (author)

186

Extrapolation ionisation chamber measurements on beta-emitting sources produced for the CEGB collaborative radiobiology programme  

International Nuclear Information System (INIS)

This report describes the structure and application of an extrapolation ionisation chamber used for measuring dose-rates from plane and point beta-emitting sources. These measurements form the basis of the dosimetry for a collaborative radiobiological study of skin to study both stochastic and non-stochastic effects. A small sample from the wide range of measurements undertaken in the programme has been selected to illustrate the procedures involved. The extrapolation chamber is currently being automated and it is intended that this report should provide a source reference to the basis of the measurements made between 1977-86. (author)

187

Windtunnel Rebuilding and Extrapolation to Flight at Transsonic Speed for ExoMars  

Science.gov (United States)

The static as well as the dynamic behaviour of the EXOMARS vehicle in the transonic velocity regime has been investigated experimentally by the Supersonic and Hypersonic Technology Department of DLR in order to investigate the behaviour prior to parachute opening. Since the experimental work was performed in air, a numerical extrapolation to flight by means of CFD is necessary. At low supersonic speed this extrapolation to flight was performed by the Spacecraft Department of the Institute of Flow Technology of DLR employing the CFD code TAU. Numerical as well as experimental results for the wind tunnel test at Mach 1.2 will be compared and discussed for three different angles of attack.

Fertig, M.; Neeb, D.; Gülhan, A.

2011-08-01

188

Atmospheric effects on the performance and threshold extrapolation of multi-temporal Landsat derived dNBR for burn severity assessment  

Science.gov (United States)

The Landsat derived differenced Normalized Burn Ratio (dNBR) is widely used for burn severity assessments. Studies of regional wildfire trends in response to climate change require consistency in dNBR mapping across multiple image dates, which may vary in atmospheric condition. Conversion of continuous dNBR images into categorical burn severity maps often requires extrapolation of dNBR thresholds from present fires for which field severity measurements such as Composite Burn Index (CBI) data are available, to historical fires for which CBI data are typically unavailable. Although differential atmospheric effects between image collection dates could lead to biased estimates of historical burn severity patterns, little is known concerning the influence of atmospheric effects on dNBR performance and threshold extrapolation. In this study, we compared the performance of dNBR calculated from six atmospheric correction methods using an optimality approach. The six correction methods included one partial (Top of atmosphere reflectance, TOA), two absolute, and three relative methods. We assessed how the correction methods affected the CBI-dNBR correlation and burn severity mapping in a Chinese boreal forest fire which occurred in 2010. The dNBR thresholds of the 2010 fire for each of the correction methods were then extrapolated to classify a historical fire from 2000. Classification accuracies of threshold extrapolations were assessed based on Cohen's Kappa analysis with 73 field-based validation plots. Our study found most correction methods improved mean dNBR optimality of the two fires. The relative correction methods generated 32% higher optimality than both TOA and absolute correction methods. All the correction methods yielded high CBI-dNBR correlations (mean R2 = 0.847) but distinctly different dNBR thresholds for severity classification of 2010 fire. Absolute correction methods could substantially increase optimality score, but were insufficient to provide a consistent scale of radiometric condition between multi-temporal Landsat images, which resulted in lower severity classification accuracies (Kappa = 0.53) than those relative correction methods (Kappa = 0.72) for the 2000 fire. Consistent radiometric response in remote sensing datasets proved essential for accuracy in regional burn severity trends monitoring. Extrapolation of empirical dNBR thresholds to historical conditions without relative normalization will likely lead to biased burn severity classifications.

Fang, Lei; Yang, Jian

2014-12-01

189

Understanding the Larson-Miller parameter. [for extrapolating stress rupture and creep properties of steels and superalloys  

Science.gov (United States)

The Larson-Miller (L-M) method of extrapolating stress rupture and creep results is based on the contention that the absolute temperature-compensated time function should have a unique value for a given material. This value should depend only on the applied stress level. The L-M method has been found satisfactory in the case of many steels and superalloys. The derivation of the L-M relation is discussed, taking into account a power law creep relationship considered by Dorn (1965) and Barrett et al. (1964), a correlation expression reported by Garofalo et al. (1961), and relations concerning the constant C. Attention is given to a verification of the validity of the considered derivation with the aid of suitable materials.

Furillo, F. T.; Purushothaman, S.; Tien, J. K.

1977-01-01

190

The riskiness of extrapolating short term nutrient retention observations to long term trends in tidal marshes  

Science.gov (United States)

Tidal marshes are among the most dynamic aquatic systems in the world. While astronomical and wind driven tides are the major driver to displace water volumes, rainfall events and evapotranspiration move the overall balance towards water export or import, respectively. Until now, only glimpses of the associated biogeochemical functioning could be obtained, usually at one or several tidal cycles scale, because there was no obvious method to obtain long term water quality data at a high temporal frequency. We have successfully managed, using UV-Vis spectrophotometers in the field, to obtain water quality and flow data on a 15-min frequency for over 20 months in a restored brackish marsh in North Carolina. This marsh was designed to intercept water generated by subsurface drainage of adjacent agricultural land before discharge to the nearby estuary. It is particularly tempting in tidal systems where tides may look very similar from one to the next, to extrapolate results obtained possibly over several days or weeks to a ';seasonal biogeochemical functioning'. The lessons learned from high frequency data at the tidal scale are fascinating, but in the longer term, we have learned that a few and inherently rare rainfall events drove the overall nutrient balance in the marsh. Continuous water quality monitoring is thus essential for two reasons: 1) to observe the short term dynamics, as they are the key to unveil possibly misunderstood biogeochemical processes, and 2) to capture the rare yet essential events which drive the system's response. However, continuous water quality monitoring on a long term basis in harsh coastal environments is not without challenges.

Birgand, F.; Etheridge, J. R.; Burchell, M. R.

2013-12-01

191

Extrapolation of multiplicity distribution in p+p(\\bar{p}) collisions to LHC energies  

Science.gov (United States)

The multiplicity (Nch) and pseudorapidity distribution (dNch/d?) of primary charged particles in p + p collisions at Large Hadron Collider (LHC) energies of \\sqrt{s} = 10 and 14 TeV are obtained from extrapolation of existing measurements at lower \\sqrt{s}. These distributions are then compared to calculations from PYTHIA and PHOJET models. The existing \\sqrt{s} measurements are unable to distinguish between a logarithmic and power law dependence of the average charged particle multiplicity (langNchrang) on \\sqrt{s}, and their extrapolation to energies accessible at LHC give very different values. Assuming a reasonably good description of inclusive charged particle multiplicity distributions by negative binomial distribution (NBD) at lower \\sqrt{s} to hold for LHC energies, we observe that the logarithmic \\sqrt{s} dependences of langNchrang are favored by the models at midrapidity. The dNch/d? versus ? distributions for the existing measurements are found to be reasonably well described by a function with three parameters which accounts for the basic features of the distribution, height at midrapidity, central rapidity plateau and the higher rapidity fall-off. Extrapolation of these parameters as a function of \\sqrt{s} is used to predict the pseudorapidity distributions of charged particles at LHC energies. dNch/d? calculations from PYTHIA and PHOJET models are found to be lower compared to those obtained from the extrapolated dNch/d? versus ? distributions for a broad ? range.

Dash, Ajay Kumar; Mohanty, Bedangadas

2010-02-01

192

Scaling and chiral extrapolation of pion mass and decay constant with maximally twisted mass QCD  

CERN Document Server

We present an update of the results for pion mass and pion decay constant as obtained by the ETM collaboration in large scale simulations with maximally twisted mass fermions and two mass degenerate flavours of light quarks. We discuss the continuum, chiral and infinite volume extrapolation of these quantities as well as the extraction of low energy constants, and investigate possible systematic uncertainties.

Dimopoulos, P; Herdoiza, G; Jansen, K; Michael, C; Urbach, C

2008-01-01

193

Scaling and chiral extrapolation of pion mass and decay constant with maximally twisted mass QCD  

International Nuclear Information System (INIS)

We present an update of the results for pion mass and pion decay constant as obtained by the ETM collaboration in large scale simulations with maximally twisted mass fermions and two mass degenerate flavours of light quarks. We discuss the continuum, chiral and infinite volume extrapolation of these quantities as well as the extraction of low energy constants, and investigate possible systematic uncertainties. (orig.)

194

Scaling and chiral extrapolation of pion mass and decay constant with maximally twisted mass QCD  

Energy Technology Data Exchange (ETDEWEB)

We present an update of the results for pion mass and pion decay constant as obtained by the ETM collaboration in large scale simulations with maximally twisted mass fermions and two mass degenerate flavours of light quarks. We discuss the continuum, chiral and infinite volume extrapolation of these quantities as well as the extraction of low energy constants, and investigate possible systematic uncertainties. (orig.)

Dimopoulos, Petros; Frezzotti, Roberto [Roma Univ. (Italy). Dipt. die Fisica; Herdoiza, Gregorio; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Michael, Chris [Liverpool Univ. (United Kingdom). Theoretical Physics Division, Dept. of Mathematical Sciences; Urbach, Carsten [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik

2008-10-15

195

Corrosion allowances for sodium heated steam generators: evaluation of effects and extrapolation to component life time  

International Nuclear Information System (INIS)

Steam generator tubes are subjected to two categories of corrosion; metal/sodium reactions and metal/water-steam interactions. Referring to these environmental conditions the relevant parameters are discussed. The influences of these parameters on the sodium corrosion and water/steam-reactions are evaluated. Extrapolations of corrosion values to steam generator design conditions are performed and discussed in detail. (author)

196

Establishing macroecological trait datasets: digitalization, extrapolation, and validation of diet preferences in terrestrial mammals worldwide  

DEFF Research Database (Denmark)

Ecological trait data are essential for understanding the broad-scale distribution of biodiversity and its response to global change. For animals, diet represents a fundamental aspect of species’ evolutionary adaptations, ecological and functional roles, and trophic interactions. However, the importance of diet for macroevolutionary and macroecological dynamics remains little explored, partly because of the lack of comprehensive trait datasets. We compiled and evaluated a comprehensive global dataset of diet preferences of mammals (“MammalDIET”). Diet information was digitized from two global and cladewide data sources and errors of data entry by multiple data recorders were assessed. We then developed a hierarchical extrapolation procedure to fill-in diet information for species with missing information. Missing data were extrapolated with information from other taxonomic levels (genus, other species within the same genus, or family) and this extrapolation was subsequently validated both internally (with a jack-knife approach applied to the compiled species-level diet data) and externally (using independent species-level diet information from a comprehensive continentwide data source). Finally, we grouped mammal species into trophic levels and dietary guilds, and their species richness as well as their proportion of total richness were mapped at a global scale for those diet categories with good validation results. The success rate of correctly digitizing data was 94%, indicating that the consistency in data entry among multiple recorders was high. Data sources provided species-level diet information for a total of 2033 species (38% of all 5364 terrestrial mammal species, based on the IUCN taxonomy). For the remaining 3331 species, diet information was mostly extrapolated from genus-level diet information (48% of all terrestrial mammal species), and only rarely from other species within the same genus (6%) or from family level (8%). Internal and external validation showed that: (1) extrapolations were most reliable for primary food items; (2) several diet categories (“Animal”, “Mammal”, “Invertebrate”, “Plant”, “Seed”, “Fruit”, and “Leaf”) had high proportions of correctly predicted diet ranks; and (3) the potential of correctly extrapolating specific diet categories varied both within and among clades. Global maps of species richness and proportion showed congruence among trophic levels, but also substantial discrepancies between dietary guilds. MammalDIET provides a comprehensive, unique and freely available dataset on diet preferences for all terrestrial mammals worldwide. It enables broad-scale analyses for specific trophic levels and dietary guilds, and a first assessment of trait conservatism in mammalian diet preferences at a global scale. The digitalization, extrapolation and validation procedures could be transferable to other trait data and taxa.

Kissling, W. Daniel; Dalby, Lars

2014-01-01

197

Establishing macroecological trait datasets: digitalization, extrapolation, and validation of diet preferences in terrestrial mammals worldwide.  

Science.gov (United States)

Ecological trait data are essential for understanding the broad-scale distribution of biodiversity and its response to global change. For animals, diet represents a fundamental aspect of species' evolutionary adaptations, ecological and functional roles, and trophic interactions. However, the importance of diet for macroevolutionary and macroecological dynamics remains little explored, partly because of the lack of comprehensive trait datasets. We compiled and evaluated a comprehensive global dataset of diet preferences of mammals ("MammalDIET"). Diet information was digitized from two global and cladewide data sources and errors of data entry by multiple data recorders were assessed. We then developed a hierarchical extrapolation procedure to fill-in diet information for species with missing information. Missing data were extrapolated with information from other taxonomic levels (genus, other species within the same genus, or family) and this extrapolation was subsequently validated both internally (with a jack-knife approach applied to the compiled species-level diet data) and externally (using independent species-level diet information from a comprehensive continentwide data source). Finally, we grouped mammal species into trophic levels and dietary guilds, and their species richness as well as their proportion of total richness were mapped at a global scale for those diet categories with good validation results. The success rate of correctly digitizing data was 94%, indicating that the consistency in data entry among multiple recorders was high. Data sources provided species-level diet information for a total of 2033 species (38% of all 5364 terrestrial mammal species, based on the IUCN taxonomy). For the remaining 3331 species, diet information was mostly extrapolated from genus-level diet information (48% of all terrestrial mammal species), and only rarely from other species within the same genus (6%) or from family level (8%). Internal and external validation showed that: (1) extrapolations were most reliable for primary food items; (2) several diet categories ("Animal", "Mammal", "Invertebrate", "Plant", "Seed", "Fruit", and "Leaf") had high proportions of correctly predicted diet ranks; and (3) the potential of correctly extrapolating specific diet categories varied both within and among clades. Global maps of species richness and proportion showed congruence among trophic levels, but also substantial discrepancies between dietary guilds. MammalDIET provides a comprehensive, unique and freely available dataset on diet preferences for all terrestrial mammals worldwide. It enables broad-scale analyses for specific trophic levels and dietary guilds, and a first assessment of trait conservatism in mammalian diet preferences at a global scale. The digitalization, extrapolation and validation procedures could be transferable to other trait data and taxa. PMID:25165528

Kissling, Wilm Daniel; Dalby, Lars; Fløjgaard, Camilla; Lenoir, Jonathan; Sandel, Brody; Sandom, Christopher; Trøjelsgaard, Kristian; Svenning, Jens-Christian

2014-07-01

198

Establishing macroecological trait datasets: digitalization, extrapolation, and validation of diet preferences in terrestrial mammals worldwide  

Science.gov (United States)

Ecological trait data are essential for understanding the broad-scale distribution of biodiversity and its response to global change. For animals, diet represents a fundamental aspect of species’ evolutionary adaptations, ecological and functional roles, and trophic interactions. However, the importance of diet for macroevolutionary and macroecological dynamics remains little explored, partly because of the lack of comprehensive trait datasets. We compiled and evaluated a comprehensive global dataset of diet preferences of mammals (“MammalDIET”). Diet information was digitized from two global and cladewide data sources and errors of data entry by multiple data recorders were assessed. We then developed a hierarchical extrapolation procedure to fill-in diet information for species with missing information. Missing data were extrapolated with information from other taxonomic levels (genus, other species within the same genus, or family) and this extrapolation was subsequently validated both internally (with a jack-knife approach applied to the compiled species-level diet data) and externally (using independent species-level diet information from a comprehensive continentwide data source). Finally, we grouped mammal species into trophic levels and dietary guilds, and their species richness as well as their proportion of total richness were mapped at a global scale for those diet categories with good validation results. The success rate of correctly digitizing data was 94%, indicating that the consistency in data entry among multiple recorders was high. Data sources provided species-level diet information for a total of 2033 species (38% of all 5364 terrestrial mammal species, based on the IUCN taxonomy). For the remaining 3331 species, diet information was mostly extrapolated from genus-level diet information (48% of all terrestrial mammal species), and only rarely from other species within the same genus (6%) or from family level (8%). Internal and external validation showed that: (1) extrapolations were most reliable for primary food items; (2) several diet categories (“Animal”, “Mammal”, “Invertebrate”, “Plant”, “Seed”, “Fruit”, and “Leaf”) had high proportions of correctly predicted diet ranks; and (3) the potential of correctly extrapolating specific diet categories varied both within and among clades. Global maps of species richness and proportion showed congruence among trophic levels, but also substantial discrepancies between dietary guilds. MammalDIET provides a comprehensive, unique and freely available dataset on diet preferences for all terrestrial mammals worldwide. It enables broad-scale analyses for specific trophic levels and dietary guilds, and a first assessment of trait conservatism in mammalian diet preferences at a global scale. The digitalization, extrapolation and validation procedures could be transferable to other trait data and taxa. PMID:25165528

Kissling, Wilm Daniel; Dalby, Lars; Fl?jgaard, Camilla; Lenoir, Jonathan; Sandel, Brody; Sandom, Christopher; Tr?jelsgaard, Kristian; Svenning, Jens-Christian

2014-01-01

199

New technique of azimuthal ambiguity resolution and non-linear force-free extrapolation applicable to near-limb magnetic regions  

Science.gov (United States)

A possibility for satisfactory removing of azimuthal ambiguity in the transverse field of vector magnetograms and the extrapolation of magnetic fields independently of the region position on the solar disk is shown. It is demonstrated an exact correspondence between the calculated field and the nonpotential loop structure in a near-limb region. The new technique of azimuthal ambiguity removing consists of the following parts: -translation of data in the form of artificial Stokes parameters into the working "quasi-spherical" coordinate system with subsequent smoothing to reduce noise component of the transverse field and with the inverse transformation to the vector form; -FFT extrapolation of the boundary potential field with constant direction of the oblique derivative corresponding to the observed line-of-sight component in the "quasi-spherical" coordinate system; -modification of the Metropolis's minimum energy method to spherical geometry with no need for data grid uniformity. Based on a version of the optimization method from Rudenko and Myshyakov (2009, Solar Phys. V. 257, 28), we use magnetograms corrected with modification of the Metropolis's method as boundary conditions for magnetic field extrapolation in the nonlinear force-free approximation.

Rudenko, George; Myshyakov, Ivan; Anfinogentov, Sergey

200

Terahertz in-line digital holography of dragonfly hindwing: amplitude and phase reconstruction at enhanced resolution by extrapolation  

CERN Document Server

We report here on terahertz (THz) digital holography on a biological specimen. A continuous-wave (CW) THz in-line holographic setup was built based on a 2.52 THz CO2 pumped THz laser and a pyroelectric array detector. We introduced novel statistical method of obtaining true intensity values for the pyroelectric array detector's pixels. Absorption and phase-shifting images of a dragonfly's hind wing were reconstructed simultaneously from single in-line hologram. Furthermore, we applied phase retrieval routines to eliminate twin image and enhanced the resolution of the reconstructions by hologram extrapolation beyond the detector area. The finest observed features are 35 {\\mu}m width cross veins.

Rong, Lu; Wang, Dayong; Zhou, Xun; Huang, Haochong; Li, Zeyu; Wang, Yunxin

2014-01-01

 
 
 
 
201

EVALUATION OF THE ADEQUACY OF THE WIND SPEED EXTRAPOLATION LAWS FOR TWO DIFFERENT ROUGHNESS METEOROLOGICAL SITES  

Directory of Open Access Journals (Sweden)

Full Text Available Increasing knowledge on wind shear models to strengthen their reliability appears as a crucial issue, markedly for energy investors to accurately predict the average wind speed at different turbine hub heights and thus the expected wind energy output. This is particularly helpful during the feasibility study to abate the costs of a wind power project. The extrapolation laws were found to provide the finest representation of the wind speed according to heights, thus avoiding installation of tall towers, or even more expensive devices such as LIDAR or SODAR. The proposed models are based on theories that determine the vertical wind profile from implicit relationships. However, these empirical extrapolation formulas have been developed for specific meteorological conditions and appropriate sites for wind turbines; reason that several studies have been made by various authors to determine the best suited formula to their own conditions. This study is aimed at proceeding the research issue addressed within a previous study, where some extrapolation models were tested and compared by extrapolating the energy resources at different heights. However, comparable results are returned by the power law and the log law which indeed proved to be preferable. In this context, this study deals the assessment of several wind speed extrapolation laws (six laws, by comparing the analytical results obtained with real data for two different meteorological Sites, different roughness, different altitudes and different measurement periods. The first site studied is an extremely rough site with daily measurements of March 2007, wind speed measurements are available at four different heights of Gantour/Gao site, obtained by the water, energy and environment company Senegal. The second site studied is a feeble rough site with monthly measurements for 2005, wind speed measurements are available at three different heights of Kuujjuarapik Site obtained by Hydro-Quebec Energy Helimax Canada. The study aims to determine the effectiveness and concordance between the extrapolation laws and the real measured data. The results show that the adjusted law is efficiently adequate for an extremely rough site and the modified laws with two other laws are efficiently adequate for a feeble rough site. The experimental results and numerical calculations exploited for the evaluation of the Weibull parameters fall the shape factors k greater than 9. The increase in altitude often causes an increase in the Weibull parameters values, however, our results show that the shape factor k can take lower values to those established in the reference altitude.

Dalila Khalfa

2014-01-01

202

{sup 131}I-CRTX internal dosimetry: animal model and human extrapolation  

Energy Technology Data Exchange (ETDEWEB)

Snake venoms molecules have been shown to play a role not only in the survival and proliferation of tumor cells but also in the processes of tumor cell adhesion, migration and angiogenesis. {sup 125}I-Crtx, a radiolabeled version of a peptide derived from Crotalus durissus terrificus snake venom, specifically binds to tumor and triggers apoptotic signalling. At the present work, {sup 125}I-Crtx biokinetic data (evaluated in mice bearing Erlich tumor) were treated by MIRD formalism to perform Internal Dosimetry studies. Doses in several organs of mice were determinate, as well as in implanted tumor, for {sup 131}I-Crtx. Doses results obtained for animal model were extrapolated to humans assuming a similar concentration ratio among various tissues between mouse and human. In the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from {sup 131}I in the tissue were considered in dose calculations. (author)

Andrade, Henrique Martins de; Ferreira, Andrea Vidal; Soares, Marcella Araugio; Silveira, Marina Bicalho; Santos, Raquel Gouvea dos [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN-CNEN-MG), Belo Horizonte, MG (Brazil)], e-mail: hma@cdtn.br

2009-07-01

203

Electric form factors of the octet baryons from lattice QCD and chiral extrapolation  

Energy Technology Data Exchange (ETDEWEB)

We apply a formalism inspired by heavy baryon chiral perturbation theory with finite-range regularization to dynamical 2+1-flavor CSSM/QCDSF/UKQCD Collaboration lattice QCD simulation results for the electric form factors of the octet baryons. The electric form factor of each octet baryon is extrapolated to the physical pseudoscalar masses, after finite-volume corrections have been applied, at six fixed values of Q{sup 2} in the range 0.2-1.3 GeV{sup 2}. The extrapolated lattice results accurately reproduce the experimental form factors of the nucleon at the physical point, indicating that omitted disconnected quark loop contributions are small. Furthermore, using the results of a recent lattice study of the magnetic form factors, we determine the ratio ?{sub p}G{sub E}{sup p}/G{sub M}{sup p}. This quantity decreases with Q{sup 2} in a way qualitatively consistent with recent experimental results.

Shanahan, P.E.; Thomas, A.W.; Young, R.D.; Zanotti, J.M. [Adelaide Univ., SA (Australia). ARC Centre of Excellence in Particle Physics at the Terascale and CSSM; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo (Japan); Pleiter, D. [Forschungszentrum Juelich (Germany). JSC; Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stueben, H. [Hamburg Univ. (Germany). Regionales Rechenzentrum; Collaboration: CSSM and QCDSF/UKQCD Collaborations

2014-03-15

204

131I-CRTX internal dosimetry: animal model and human extrapolation  

International Nuclear Information System (INIS)

Snake venoms molecules have been shown to play a role not only in the survival and proliferation of tumor cells but also in the processes of tumor cell adhesion, migration and angiogenesis. 125I-Crtx, a radiolabeled version of a peptide derived from Crotalus durissus terrificus snake venom, specifically binds to tumor and triggers apoptotic signalling. At the present work, 125I-Crtx biokinetic data (evaluated in mice bearing Erlich tumor) were treated by MIRD formalism to perform Internal Dosimetry studies. Doses in several organs of mice were determinate, as well as in implanted tumor, for 131I-Crtx. Doses results obtained for animal model were extrapolated to humans assuming a similar concentration ratio among various tissues between mouse and human. In the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from 131I in the tissue were considered in dose calculations. (author)

205

{sup 131}I-SPGP internal dosimetry: animal model and human extrapolation  

Energy Technology Data Exchange (ETDEWEB)

Scorpaena plumieri is commonly called moreia-ati or manganga and is the most venomous and one of the most abundant fish species of the Brazilian coast. Soprani 2006, demonstrated that SPGP - an isolated protein from S. plumieri fish- possess high antitumoral activity against malignant tumours and can be a source of template molecules for the development (design) of antitumoral drugs. In the present work, Soprani's {sup 125}ISPGP biokinetic data were treated by MIRD formalism to perform Internal Dosimetry studies. Absorbed doses due to the {sup 131}I-SPGP uptake were determinate in several organs of mice, as well as in the implanted tumor. Doses obtained for animal model were extrapolated to humans assuming a similar ratio for various mouse and human tissues. For the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from {sup 131}I were considered. (author)

Andrade, Henrique Martins de; Ferreira, Andrea Vidal; Soprani, Juliana; Santos, Raquel Gouvea dos [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN-CNEN-MG), Belo Horizonte, MG (Brazil)], e-mail: hma@cdtn.br; Figueiredo, Suely Gomes de [Universidade Federal do Espirito Santo, (UFES), Vitoria, ES (Brazil). Dept. de Ciencias Fisiologicas. Lab. de Quimica de Proteinas

2009-07-01

206

Applications and limitations of interspecies scaling and in vitro extrapolation in pharmacokinetics.  

Science.gov (United States)

The search for new drugs is an extremely time-consuming and costly endeavor. Much of the time and cost are expended on generating data that support the efficacy and safety profiles of the drug. Because of ethical constraints, relevant pharmacological and toxicological assessments must be made in laboratory animals and in in vitro systems before human testing can begin. In support of the efficacy and safety evaluation during drug development, two fundamental challenges facing industrial drug metabolism scientists are (1) how to "scale-up" the pharmacokinetic data from animals to humans and (2) how to extrapolate the in vitro data to the in vivo situation. This review examines the applications and limitations of interspecies scaling and in vitro extrapolation in pharmacokinetics. PMID:9860929

Lin, J H

1998-12-01

207

Chiral extrapolation and finite-volume dependence of the hyperon vector couplings  

Science.gov (United States)

The hyperon vector form factors at zero momentum transfer, f1(0), play an important role in a precise determination of the Cabibbo-Kobayashi-Maskawa matrix element Vus. Recent studies based on lattice chromodynamics (LQCD) simulations and covariant baryon chiral perturbation theory yield contradicting results. In this work, we study chiral extrapolation of and finite-volume corrections to the latest nf=2+1 LQCD simulations. Our results show that finite-volume corrections are relatively small and can be safely ignored at the present LQCD setup of m?L =4.6, but chiral extrapolation needs to be performed more carefully. Nevertheless, the discrepancy remains, and further studies are needed to fully understand it.

Geng, Li-Sheng; Li, Kai-Wen; Camalich, J. Martin

2014-06-01

208

Chiral extrapolation and finite-volume dependence of the hyperon vector couplings  

CERN Document Server

The hyperon vector form factors at zero momentum transfer, $f_1(0)$, play an important role in a precise determination of the Cabibbo-Kobayashi-Maskawa matrix element $V_{us}$. Recent studies based on lattice chromodynamics (LQCD) simulations and covariant baryon chiral perturbation theory yield contradicting results. In this work, we study chiral extrapolation of and finite-volume corrections to the latest $n_f=2+1$ LQCD simulations. Our results show that finite-volume corrections are relatively small and can be safely ignored at the present LQCD setup of $m_\\pi L=4.6$ but chiral extrapolation needs to be performed more carefully. Nevertheless, the discrepancy remains and further studies are needed to fully understand it.

Geng, Li-Sheng; Camalich, J Martin

2014-01-01

209

Chiral extrapolations in 2+1 flavor domain wall fermion simulations  

Science.gov (United States)

Simulations with 2+1 flavors of domain wall fermions provide us with the opportunity to compare the lattice data directly to the predictions of continuum chiral perturbation theory, up to correc- tions from the residual chiral symmetry breaking, mres , and O(a) lattice artefacts, which are rela- tively small for domain wall fermions. We present preliminary results for the pseudoscalar meson masses and decay constants from partially quenched simulations and examine the next-to-leading order chiral extrapolations at small quark masses. The simulations were carried out on two lattice volumes : 163 × 32 and 243 × 64, with the lattice spacing fixed at about 0.1 fm. The subtleties of the chiral fits are discussed. We also explore the roles of mres and O(a) terms in the NLO chiral expansions and their effects on the chiral extrapolations for the pseudoscalar masses and decay constants.

Lin, Meifeng

2006-12-01

210

Neutron spectroscopy results of JET high-performance plasmas and extrapolations to DT performance.  

Science.gov (United States)

In a fusion reactor with high energy gain, the fusion power will be mainly thermonuclear (THN). Measurements of the THN neutron rate are a good performance indicator of a fusion plasma, requiring neutron emission spectroscopy (NES) measurements to distinguish thermal and nonthermal contributions. We report here on recent NES results from JET high-performance plasmas with high fractions (about 65%) of THN emission. The analysis is made with a framework for analyzing NES data, taking into account THN reactions and beam-target reactions. The results are used to extrapolate to the equivalent DT rates. Finally, we discuss the applicability of using NES in the deuterium phase of ITER, both for the extrapolations to ITER’s future DT performance as well as for the measurements of confined energetic ions. PMID:21058461

Hellesen, C; Andersson Sundén, E; Conroy, S; Ericsson, G; Eriksson, J; Gatu Johnson, M; Weiszflog, M

2010-10-01

211

Multiphase-field approach for multicomponent alloys with extrapolation scheme for numerical application.  

Science.gov (United States)

A multiphase-field model previously proposed by the authors is reformulated in a thermodynamically consistent form and extended to multicomponent systems. The phase-field and diffusion equations, derived from a free energy functional, are compared to those postulated in the previous model in the limit of a binary alloy. The constraint of local quasiequilibrium, which is equivalent to the postulate of equal diffusion potentials for coexisting phases, is deduced from a variational principle. Solute partitioning and evaluation of the thermodynamic driving force for phase transformation are done by numerical minimization of the free energy of the multiphase system using the Calphad approach. A local extrapolation scheme which enhances the computational efficiency for complex numerical simulations of technical alloys is presented. It is shown that this extrapolation scheme, used in a "multibinary" approximation, reproduces the former model without restriction to dilute solutions. PMID:16906929

Eiken, J; Böttger, B; Steinbach, I

2006-06-01

212

Electric form factors of the octet baryons from lattice QCD and chiral extrapolation  

CERN Document Server

We apply a formalism inspired by heavy baryon chiral perturbation theory with finite-range regularization to dynamical $2+1-$flavor CSSM/QCDSF/UKQCD Collaboration lattice QCD simulation results for the electric form factors of the octet baryons. The electric form factor of each octet baryon is extrapolated to the physical pseudoscalar masses, after finite-volume corrections have been applied, at six fixed values of $Q^2$ in the range 0.2-1.3 GeV$^2$. The extrapolated lattice results accurately reproduce the experimental form factors of the nucleon at the physical point, indicating that omitted disconnected quark loop contributions are small. Furthermore, using the results of a recent lattice study of the magnetic form factors, we determine the ratio $\\mu_p G^p_E/G^p_M$. This quantity decreases with $Q^2$ in a way qualitatively consistent with recent experimental results.

Shanahan, P E; Young, R D; Zanotti, J M; Horsley, R; Nakamura, Y; Pleiter, D; Rakow, P E L; Schierholz, G; Stüben, H

2014-01-01

213

Spatial extrapolation of foF2 predictions using nonlinear techniques  

Science.gov (United States)

Time series of ionospheric F2 layer critical frequency, foF2, from European ionosonde stations are used to evaluate the spatial extrapolation of foF2 from one station to another using nonlinear techniques. One-hour ahead prediction models are constructed using radial basis function neural networks (RBF-NNs). Model predictive accuracy is presented in the form of normalized root-mean-squared error (NRMSE) for both self-predictions and cross-predictions of foF2. The results show a clear improvement in predictive accuracy when compared with the reference persistence model. Furthermore, the nonlinear cross-predictions from one station to another show improvements over persistence self-predictions. The longitudinal and latitudinal dependencies of spatial extrapolations are examined. Preliminary results suggest that the longitudinal dependency of the model predictions dominates over their latitude dependency.

Chan, A.; Cannon, P.

214

Subsequent entry biologics (biosimilars in Canada: approaches to interchangeability and the extrapolation of indications and uses  

Directory of Open Access Journals (Sweden)

Full Text Available The principles Health Canada use when extrapolating the indications and uses of a biosimilar product subsequent to a single clinical trial or limited number and scope of clinical trials during product development are discussed. The principles underlying the regulatory framework for Subsequent Entry Biologics (SEBs or biosimilars in Canada explain the position taken by the regulator in respect of the substitutability and/or interchangeability of SEBs.

Agnes V Klein

2014-11-01

215

About extrapolation of coupling constant of vertex ? ? 3? to low-energy limit  

International Nuclear Information System (INIS)

The use of some model procedures for extrapolation of coupling constant F3? of ? ? 3? vertex from physical region to low-energy limit is examined. It is shown that in all the model concerned a possible difference between experimental value F3? = (12.9±0.9±0.5) GeV-3 and F3?(0) is about 1 GeV-3. 8 refs.; 1 tab

216

Charge symmetry breaking from a chiral extrapolation of moments of quark distribution functions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a determination, from lattice QCD, of charge symmetry violation in the spin- independent and spin-dependent parton distribution functions of the nucleon. This is done by chirally extrapolating recent QCDSF/UKQCD Collaboration lattice simulations of the first several Mellin moments of the parton distribution functions of octet baryons to the physical point. We find small chiral corrections for the polarized moments, while the corrections are quantitatively signific...

Shanahan, P. E.; Thomas, A. W.; Young, R. D.

2013-01-01

217

Assessment of aquatic experimental versus predicted and extrapolated chronic toxicity data of four structural analogues.  

Science.gov (United States)

The present study was developed to assess the chronic toxicity predictions and extrapolations for a set of chlorinated anilines (aniline (AN), 4-chloroaniline (CA), 3,5-dichloroaniline (DCA) and 2,3,4-trichloroaniline (TCA)). Daphnia magna 21 d chronic experimental data was compared to the chronic toxicity predictions made by the US EPA ECOSAR QSAR tools and to acute-to-chronic extrapolations. Additionally, Species Sensitivity Distributions (SSDs) were constructed to assess the chronic toxicity variability among different species and to investigate the acute versus chronic toxicity in a multi-species context. Since chlorinated anilines are structural analogues with a designated polar narcotic mode of action, similar toxicity responses were assumed. However, rather large interchemical and interspecies differences in toxicity were observed. Compared to the other three test compounds, TCA exposure had a significantly larger impact on growth and reproduction of D. magna. Furthermore, this study illustrated that QSARs or a fixed ACR are not able to account for these interchemical and interspecies differences. Consequently, ECOSAR was found to be inadequate to predict the chronic toxicity of the anilines and the use of a fixed ACR (of 10) led to under of certain species. The experimental ACRs determined in D. magna were substantially different among the four aromatic amines (ACR of 32 for AN, 16.9 for CA, 5.7 for DCA and 60.8 for TCA). Furthermore, the SSDs illustrated that Danio rerio was rather insensitive to AN in comparison to another fish species, Phimphales promelas. It was therefore suggested that available toxicity data should be used in an integrative multi-species way, rather than using individual-based toxicity extrapolations. In this way, a relevant overview of the differences in species sensitivity is given, which in turn can serve as the basis for acute to chronic extrapolations. PMID:21944038

Dom, Nathalie; Knapen, Dries; Blust, Ronny

2012-01-01

218

Accelerated, energy-conserving Born-Oppenheimer molecular dynamics via Fock matrix extrapolation.  

Science.gov (United States)

Born-Oppenheimer molecular dynamics calculations, especially those that exploit information retained from previous time steps in order to accelerate convergence of the electronic structure calculations, can suffer from systematic error in the energy gradient that manifests as a drift in the microcanonical energy. Here, we demonstrate that this is only the case when the self-consistent field (SCF) convergence criterion is set too low; using only a marginally tighter threshold (still two orders of magnitude lower than what is standard for geometry optimizations), the drift disappears completely, for a time scale of several picoseconds. Using a Fock matrix extrapolation technique, SCF convergence is achieved in as few as three iterations per time step, without sacrificing energy conservation. In test calculations for C2F4, (H2O4-, (H2O6, and [Fe(H2O6]2+, we demonstrate energy-conserving Fock matrix extrapolation that reduces the number of SCF cycles by up to 70% and reduces the computer time per molecular dynamics step by 45-55%, relative to simulations performed without extrapolation. PMID:16240040

Herbert, John M; Head-Gordon, Martin

2005-09-21

219

Estimation of the extrapolation error in the calibration of type S thermocouples  

Science.gov (United States)

Measurement results from the calibration performed at NIST of ten new type S thermocouples have been analyzed to estimate the extrapolation error. Thermocouples have been calibrated at the fixed points of Zn, Al, Ag and Au and calibration curves were calculated using different numbers of FPs. It was found for these thermocouples that the absolute value of the extrapolation error, evaluated by measurement at the Au freezing-point temperature, is at most 0.10 °C and 0.27 °C when the fixed-points of Zn, Al and Ag, or the fixed-points of Zn and Al, are respectively used to calculate the calibration curve. It is also shown that absolute value of the extrapolation error, evaluated by measurement at the Ag freezing-point temperature is at most 0.25 °C when the fixed-points of Zn and Al, are used to calculate the calibration curve. This study is oriented to help those labs that lack a direct mechanism to achieve a high temperature calibration. It supports, up to 1064 °C, the application of a similar procedure to that used by Burns and Scroger in NIST SP-250-35 for calibrating a new type S thermocouple. The uncertainty amounts a few tenths of a degree Celsius.

Giorgio, P.; Garrity, K. M.; Rebagliati, M. Jiménez; García Skabar, J.

2013-09-01

220

Böhm extrapolation chamber: Study of its behavior in beta radiation fields at the Calibration Laboratory of IPEN  

Science.gov (United States)

The Calibration Laboratory (LCI) at the Instituto de Pesquisas Energéticas e Nucleares (IPEN) is going to establish a Böhm extrapolation chamber as a primary standard system for the dosimetry and calibration of beta radiation sources and detectors. This chamber was already tested in beta radiation beams with an aluminized Mylar entrance window, and now, it was characterized with an original Hostaphan entrance window. A comparison between the results of the extrapolation chamber with the two entrance windows was performed. The results showed that this extrapolation chamber presents the same effectiveness in beta radiation fields as a primary standard system with both entrance windows, showing that any one of them may be utilized.

Antonio, Patrícia L.; Xavier, Marcos; Caldas, Linda V. E.

2014-11-01

 
 
 
 
221

Neural extrapolation of motion for a ball rolling down an inclined plane.  

Science.gov (United States)

It is known that humans tend to misjudge the kinematics of a target rolling down an inclined plane. Because visuomotor responses are often more accurate and less prone to perceptual illusions than cognitive judgments, we asked the question of how rolling motion is extrapolated for manual interception or drawing tasks. In three experiments a ball rolled down an incline with kinematics that differed as a function of the starting position (4 different positions) and slope (30°, 45° or 60°). In Experiment 1, participants had to punch the ball as it fell off the incline. In Experiment 2, the ball rolled down the incline but was stopped at the end; participants were asked to imagine that the ball kept moving and to punch it. In Experiment 3, the ball rolled down the incline and was stopped at the end; participants were asked to draw with the hand in air the trajectory that would be described by the ball if it kept moving. We found that performance was most accurate when motion of the ball was visible until interception and haptic feedback of hand-ball contact was available (Experiment 1). However, even when participants punched an imaginary moving ball (Experiment 2) or drew in air the imaginary trajectory (Experiment 3), they were able to extrapolate to some extent global aspects of the target motion, including its path, speed and arrival time. We argue that the path and kinematics of a ball rolling down an incline can be extrapolated surprisingly well by the brain using both visual information and internal models of target motion. PMID:24940874

La Scaleia, Barbara; Lacquaniti, Francesco; Zago, Myrka

2014-01-01

222

Two photon decay of the pseudoscalars, the extrapolation to the mass-shell  

CERN Document Server

The extrapolation of the decay amplitude of the pseudoscalar mesons into two photons from the soft meson limit where it is obtained from the axial anomaly to the mass-shell involves the contribution of the 0 minus continuum. The corrections to the soft-meson limit is estimated and turns out to be very large for the eta and eta'. The results, however, remain consistent with the values of the singlet-octet mixing angle theta =-19.5 degree and the ratio f8/fpi=1.25 obtained from the chiral perturbation theory.

Nasrallah, N F

2001-01-01

223

Model of a realistic InP surface quantum dot extrapolated from atomic force microscopy results.  

Science.gov (United States)

We report on numerical simulations of a zincblende InP surface quantum dot (QD) on In?.??Ga?.?? buffer. Our model is strictly based on experimental structures, since we extrapolated a three-dimensional dot directly by atomic force microscopy results. Continuum electromechanical, [Formula: see text] bandstructure and optical calculations are presented for this realistic structure, together with benchmark calculations for a lens-shape QD with the same radius and height of the extrapolated dot. Interesting similarities and differences are shown by comparing the results obtained with the two different structures, leading to the conclusion that the use of a more realistic structure can provide significant improvements in the modeling of QDs fact, the remarkable splitting for the electron p-like levels of the extrapolated dot seems to prove that a realistic experimental structure can reproduce the right symmetry and a correct splitting usually given by atomistic calculations even within the multiband [Formula: see text] approach. Moreover, the energy levels and the symmetry of the holes are strongly dependent on the shape of the dot. In particular, as far as we know, their wave function symmetries do not seem to resemble to any results previously obtained with simulations of zincblende ideal structures, such as lenses or truncated pyramids. The magnitude of the oscillator strengths is also strongly dependent on the shape of the dot, showing a lower intensity for the extrapolated dot, especially for the transition between the electrons and holes ground state, as a result of a relevant reduction of the wave functions overlap. We also compare an experimental photoluminescence spectrum measured on an homogeneous sample containing about 60 dots with a numerical ensemble average derived from single dot calculations. The broader energy range of the numerical spectrum motivated us to perform further verifications, which have clarified some aspects of the experimental results and helped us to develop a suitable model for the spectrum, by assuming a not equiprobable weight from each dot, a model which is extremely consistent with the experimental data. PMID:24763365

Barettin, Daniele; De Angelis, Roberta; Prosposito, Paolo; Auf der Maur, Matthias; Casalboni, Mauro; Pecchia, Alessandro

2014-05-16

224

Magnetic form factors of the octet baryons from lattice QCD and chiral extrapolation  

Energy Technology Data Exchange (ETDEWEB)

We present a 2+1-flavor lattice QCD calculation of the electromagnetic Dirac and Pauli form factors of the octet baryons. The magnetic Sachs form factor is extrapolated at six fixed values of Q{sup 2} to physical pseudoscalar masses and infinite volume using a formulation based on heavy baryon chiral perturbation theory with finite-range regularization. We properly account for omitted disconnected quark contractions using a partially-quenched effective field theory formalism. The results compare well with the experimental form factors of the nucleon and the magnetic moments of the octet baryons.

Shanahan, P.E.; Thomas, A.W.; Young, R.D.; Zanotti, J.M. [Adelaide Univ. (Australia). School of Chemistry and Physics; Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo (Japan); Pleiter, D. [Forschungszentrum Juelich GmbH (Germany). Juelich Supercomputing Centre (JSC); Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stueben, H. [Hamburg Univ. (Germany). Regionales Rechenzentrum; Collaboration: CSSM and QCDSF/UKQCD Collaborations

2014-01-15

225

Magnetic form factors of the octet baryons from lattice QCD and chiral extrapolation  

CERN Document Server

We present a 2+1--flavor lattice QCD calculation of the electromagnetic Dirac and Pauli form factors of the octet baryons. The magnetic Sachs form factor is extrapolated at six fixed values of $Q^2$ to physical pseudoscalar masses and infinite volume using a formulation based on heavy baryon chiral perturbation theory with finite-range regularization. We properly account for omitted disconnected quark contractions using a partially-quenched effective field theory formalism. The results compare well with the experimental form factors of the nucleon and the magnetic moments of the octet baryons.

Shanahan, P E; Young, R D; Zanotti, J M; Horsley, R; Nakamura, Y; Pleiter, D; Rakow, P E L; Schierholz, G; Stüben, H

2014-01-01

226

R-matrix and Potential Model Extrapolations for NACRE Update and Extension Project  

International Nuclear Information System (INIS)

NACRE, the 'nuclear astrophysics compilation of reaction rates', has been widely utilized in stellar evolution and nucleosynthesis studies. Its update and extension programme started within a Konan-Universite Libre de Bruxelles (ULB) collaboration. At the present moment, experimental data in refereed journals have been collected, and their theoretical extrapolations are being performed using the R-matrix or potential models. For the 3H(d,n)4He and 2H(p,?)3He reactions, we present preliminary results that could well reproduce the experimental data

227

R-matrix and Potential Model Extrapolations for NACRE Update and Extension Project  

Science.gov (United States)

NACRE, the `nuclear astrophysics compilation of reaction rates', has been widely utilized in stellar evolution and nucleosynthesis studies. Its update and extension programme started within a Konan-Université Libre de Bruxelles (ULB) collaboration. At the present moment, experimental data in refereed journals have been collected, and their theoretical extrapolations are being performed using the R-matrix or potential models. For the 3H(d,n)4He and 2H(p,?)3He reactions, we present preliminary results that could well reproduce the experimental data.

Aikawa, Masayuki; Arai, Koji; Katsuma, Masahiko; Takahashi, Kohji; Arnould, Marcel; Utsunomiya, Hiroaki

2006-07-01

228

Model of a realistic InP surface quantum dot extrapolated from atomic force microscopy results  

Science.gov (United States)

We report on numerical simulations of a zincblende InP surface quantum dot (QD) on \\text{I}{{\\text{n}}_{0.48}}\\text{G}{{\\text{a}}_{0.52}}\\text{P} buffer. Our model is strictly based on experimental structures, since we extrapolated a three-dimensional dot directly by atomic force microscopy results. Continuum electromechanical, \\vec{k}\\;\\cdot \\;\\vec{p} bandstructure and optical calculations are presented for this realistic structure, together with benchmark calculations for a lens-shape QD with the same radius and height of the extrapolated dot. Interesting similarities and differences are shown by comparing the results obtained with the two different structures, leading to the conclusion that the use of a more realistic structure can provide significant improvements in the modeling of QDs fact, the remarkable splitting for the electron p-like levels of the extrapolated dot seems to prove that a realistic experimental structure can reproduce the right symmetry and a correct splitting usually given by atomistic calculations even within the multiband \\vec{k}\\;\\cdot \\;\\vec{p} approach. Moreover, the energy levels and the symmetry of the holes are strongly dependent on the shape of the dot. In particular, as far as we know, their wave function symmetries do not seem to resemble to any results previously obtained with simulations of zincblende ideal structures, such as lenses or truncated pyramids. The magnitude of the oscillator strengths is also strongly dependent on the shape of the dot, showing a lower intensity for the extrapolated dot, especially for the transition between the electrons and holes ground state, as a result of a relevant reduction of the wave functions overlap. We also compare an experimental photoluminescence spectrum measured on an homogeneous sample containing about 60 dots with a numerical ensemble average derived from single dot calculations. The broader energy range of the numerical spectrum motivated us to perform further verifications, which have clarified some aspects of the experimental results and helped us to develop a suitable model for the spectrum, by assuming a not equiprobable weight from each dot, a model which is extremely consistent with the experimental data.

Barettin, Daniele; De Angelis, Roberta; Prosposito, Paolo; Auf der Maur, Matthias; Casalboni, Mauro; Pecchia, Alessandro

2014-05-01

229

RF-sheath heat flux estimates on Tore Supra and JET ICRF antennae. Extrapolation to ITER  

International Nuclear Information System (INIS)

RF-sheath induced heat loads are identified from infrared thermography measurements on Tore Supra ITER-like prototype and JET A2 antennae, and are quantified by fitting thermal calculations. Using a simple scaling law assessed experimentally, the estimated heat fluxes are then extrapolated to the ITER ICRF launcher delivering 20 MW RF power for several plasma scenarios. Parallel heat fluxes up to 6.7 MW/m2 are expected very locally on ITER antenna front face. The role of edge density on operation is stressed as a trade-off between easy RF coupling and reasonable heat loads. Sources of uncertainty on the results are identified.

230

Extrapolation of the Dutch 1 MW tunable free electron maser to a 5 MW ECRH source  

International Nuclear Information System (INIS)

A Free Electron Maser (FEM) is now under construction at the FOM Institute (Rijnhuizen) Netherlands with the goal of producing 1 MW long pulse to CW microwave output in the range 130 GHz to 250 GHz with wall plug efficiencies of 50% (Verhoeven, et al EC-9 Conference). An extrapolated version of this device is proposed which by scaling up the beam current, would produce microwave power levels of up to 5 MW CW in order to reduce the cost per watt and increase the power per module, thus providing the fusion community with a practical ECRH source

231

Magnetic form factors of the octet baryons from lattice QCD and chiral extrapolation  

International Nuclear Information System (INIS)

We present a 2+1-flavor lattice QCD calculation of the electromagnetic Dirac and Pauli form factors of the octet baryons. The magnetic Sachs form factor is extrapolated at six fixed values of Q2 to physical pseudoscalar masses and infinite volume using a formulation based on heavy baryon chiral perturbation theory with finite-range regularization. We properly account for omitted disconnected quark contractions using a partially-quenched effective field theory formalism. The results compare well with the experimental form factors of the nucleon and the magnetic moments of the octet baryons.

232

CHARACTERISTICS OF THE H-MODE PEDESTAL AND EXTRAPOLATION TO ITER  

Energy Technology Data Exchange (ETDEWEB)

A271 CHARACTERISTICS OF THE H-MODE PEDESTAL AND EXTRAPOLATION TO ITER. The peeling-ballooning mode model for edge stability along with a model for the H-mode transport barrier width is used as an approach to estimating the H-mode pedestal conditions in ITER. Scalings of the barrier width based on ion-orbit loss, neutral penetration, and turbulence suppression are examined and empirical scalings of the barrier width are presented. An empirical scaling for the pedestal {beta} is derived based on ideas from stability and the empirical width scaling. The impact of the stability model and other factors on ELM size is discussed.

OSBORNE,TH; CORDEY,JG; GROEBNER,RJ; HATAE,T; HUBBARD,A; HORTON,LD; KAMADA,Y; KRITZ,A; LAO,LL; LEONARD,AW; LOARTE,A; MAHDAVI,MA; MOSSESSIAN,D; ONJUN,T; OSSENPENKO,M; ROGNLIEN,TD; SAIBNE,G; SNYDER,PB; SUGIHARA,M; SHURYGIN,R; THOMSEN,K; WADE,MR; WILSON,HR; XU,XQ; YATSU,K

2002-11-01

233

On the problem of extrapolating the data on Sr90 behaviour in dogs to a human organism  

International Nuclear Information System (INIS)

Regularities in the metabolism of radiostrontium have been comparatively studied in dogs and man. The fact revealed that they are the same makes it possible to extrapolate the radiostrontium doses used for dogs to a human organism

234

Evolution of the Fine Structure of Magnetic Fields in the Quiet Sun: Observations from Sunrise/IMaX and Extrapolations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Observations with the balloon-borne Sunrise/Imaging Magnetograph eXperiment (IMaX) provide high spatial resolution (roughly 100 km at disk center) measurements of the magnetic field in the photosphere of the quiet Sun. To investigate the magnetic structure of the chromosphere and corona, we extrapolate these photospheric measurements into the upper solar atmosphere and analyze a 22-minute long time series with a cadence of 33 seconds. Using the extrapolated magnetic-field lines as tracer, w...

Wiegelmann, T.; Solanki, S.; Borrero, J.; Peter, H.; Barthol, P.; Gandorfer, A.; Marti?nez pillet, V.; Schmidt, W.; Kno?lker, M.

2013-01-01

235

Accuracy of the diffusion equation with extrapolated-boundary condition for transmittance of light through a turbid medium  

CERN Document Server

The linear intensity profile of multiply scattered light in a slab geometry extrapolates to zero at a certain distance beyond the boundary. The diffusion equation with this "extrapolated boundary condition" has been used in the literature to obtain analytical formulas for the transmittance of light through the slab as a function of angle of incidence and refractive index. The accuracy of these formulas is determined by comparison with a numerical solution of the Boltzmann equation for radiative transfer.

Paasschens, J C J; Beenakker, C W J

2008-01-01

236

Corrosion and corrosion control of mild steel in concentrated H2SO4 solutions by a newly synthesized glycine derivative  

International Nuclear Information System (INIS)

Graphical abstract: Display Omitted Research highlights: ? GlyD1 exhibits inhibiting properties more than GlyD2 and Gly. ? Inhibition efficiency increases with inhibitor concentration. ? Inhibition efficiency decreases with temperature, suggesting physical adsorption. ? Validation of corrosion rates measured by Tafel extrapolation method is confirmed. - Abstract: A newly synthesized glycine derivative (GlyD1), 2-(4-(dimethylamino)benzylamino)acetic acid hydrochloride, was used to control mild steel corrosion in 4.0 M H2SO4 solutions at different temperatures (278-338 K). Tafel extrapolation, linear polarization resistance (LPR) and impedance methods were used to test corrosion inhibitor efficiency. An independent method of chemical analysis, namely ICP-AES (inductively coupled plasma atomic emission spectrometry) was also used to test validity of corrosion rate measured by Tafel extrapolation method. Results obtained were compared with an available glycine derivative (GlyD2) and glycine (Gly). Tafel polarization measurements revealed that the three tested inhibitors function as mixed-type compounds. The inhibition efficiency increased with increase in inhibitor concentration and decreased with temperature, suggesting the occurrence of physical adsorption. The adsorptive behaviour of the three inhibitors followed Temkin-type isotherm and the standard free energy changes of adsorption (?Gadso) were evaluated for the to) were evaluated for the three tested inhibitors as a function of temperature. The inhibition performance of GlyD1 was much better than those of GlyD2 and Gly itself. Results obtained from the different corrosion evaluation techniques were in good agreement.

237

Improved spatial resolution in time-resolved transillumination imaging using temporal extrapolation with the cumulant expansion solution to the transport equation  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish Este artículo presenta resultados de un método para la formación de imágenes resueltas temporalmente mediante la transmisión de luz usando una extrapolación temporal. La extrapolación temporal se realiza mediante la solución a la ecuación de transporte mediante la expansión en cumulantes. Los result [...] ados obtenidos se comparan con los resultados del mismo método pero usando la solución mediante la aproximación de difusión. Se encuentra que los resultados son consistentes pero la el método usando la expansión en cumulantes da mejor resolución, en un factor de aproximadamente 3, para el proceso de formación de imágenes, esto debido a que da una mejor estimación de la contribución de los fotones con tiempos de integración menores. Abstract in english This paper presents results of a time-resolved transillumination imaging method using temporal extrapolation. The temporal extrapolation is performed with the cumulant expansion solution to the transport equation. The results obtained are compared to results of the same method but using the diffusio [...] n approximation solution. It is found that the results are consistent but that the cumulant expansion method gives better resolution, by a factor of approximately 3, for the imaging process, because it gives a better estimation of the photon contribution for shorter integration times.

E., Ortiz-Rascón; N. C., Bruce; A. A., Rodríguez-Rosales; J., Garduño-Mejía; R., Ortega-Martínez.

2014-02-01

238

Monitoring corrosion and corrosion control of iron in HCl by non-ionic surfactants of the TRITON-X series - Part II. Temperature effect, activation energies and thermodynamics of adsorption  

International Nuclear Information System (INIS)

Research highlights: ? TX-305 exhibits inhibiting properties for iron corrosion more than TX-165 and TX 100. ? Inhibition efficiency increases with temperature, suggesting chemical adsorption. ? The three tested surfactants act as mixed-type inhibitors with cathodic predominance. ? Validation of corrosion rates measured by Tafel extrapolation method is confirmed. - Abstract: The inhibition characteristics of non-ionic surfactants of the TRITON-X series, namely TRITON-X-100 (TX-100), TRITON-X-165 (TX-165) and TRITON-X-305 (TX-305), on the corrosion of iron was studied in 1.0 M HCl solutions as a function of inhibitor concentration (0.005-0.075 g L-1) and solution temperature (278-338 K). Measurements were conducted based on Tafel extrapolation method. Electrochemical frequency modulation (EFM), a non-destructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, is also presented. Experimental corrosion rates determined by the Tafel extrapolation method were compared with corrosion rates obtained by the EFM technique and an independent method of chemical analysis. The chemical method of confirmation of the corrosion rates involved determination of the dissolved cation, using ICP-AES (inductively coupled plasma atomic emission spectrometry). The aim was to confirm validation of corrosion rates measured by the Tafel extrapolation method. Results obtained showed that, in all cass obtained showed that, in all cases, the inhibition efficiency increased with increase in temperature, suggesting that chemical adsorption occurs. The adsorptive behaviour of the three surfactants followed Temkin-type isotherm. The standard free energies of adsorption decreased with temperature, reflecting better inhibition performance. These findings confirm chemisorption of the tested inhibitors. Thermodynamic activation functions of the dissolution process were also calculated as a function of each inhibitor concentration. All the results obtained from the methods employed are in reasonable agreement.

239

Monitoring corrosion and corrosion control of iron in HCl by non-ionic surfactants of the TRITON-X series - Part II. Temperature effect, activation energies and thermodynamics of adsorption  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: TX-305 exhibits inhibiting properties for iron corrosion more than TX-165 and TX 100. Inhibition efficiency increases with temperature, suggesting chemical adsorption. The three tested surfactants act as mixed-type inhibitors with cathodic predominance. Validation of corrosion rates measured by Tafel extrapolation method is confirmed. - Abstract: The inhibition characteristics of non-ionic surfactants of the TRITON-X series, namely TRITON-X-100 (TX-100), TRITON-X-165 (TX-165) and TRITON-X-305 (TX-305), on the corrosion of iron was studied in 1.0 M HCl solutions as a function of inhibitor concentration (0.005-0.075 g L{sup -1}) and solution temperature (278-338 K). Measurements were conducted based on Tafel extrapolation method. Electrochemical frequency modulation (EFM), a non-destructive corrosion measurement technique that can directly give values of corrosion current without prior knowledge of Tafel constants, is also presented. Experimental corrosion rates determined by the Tafel extrapolation method were compared with corrosion rates obtained by the EFM technique and an independent method of chemical analysis. The chemical method of confirmation of the corrosion rates involved determination of the dissolved cation, using ICP-AES (inductively coupled plasma atomic emission spectrometry). The aim was to confirm validation of corrosion rates measured by the Tafel extrapolation method. Results obtained showed that, in all cases, the inhibition efficiency increased with increase in temperature, suggesting that chemical adsorption occurs. The adsorptive behaviour of the three surfactants followed Temkin-type isotherm. The standard free energies of adsorption decreased with temperature, reflecting better inhibition performance. These findings confirm chemisorption of the tested inhibitors. Thermodynamic activation functions of the dissolution process were also calculated as a function of each inhibitor concentration. All the results obtained from the methods employed are in reasonable agreement.

Amin, Mohammed A., E-mail: maaismail@yahoo.co [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia); Department of Chemistry, Faculty of Science, Ain shams University, 11566 Abbassia, Cairo (Egypt); Ahmed, M.A. [Physics Department, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia); Arida, H.A. [Materials and Corrosion Lab (MCL), Department of Chemistry, Faculty of Science, Taif University, 888 Hawiya (Saudi Arabia); Arslan, Taner [Department of Chemistry, Eskisehir Osmangazi University, 26480 Eskisehir (Turkey); Saracoglu, Murat [Faculty of Education, Erciyes University, 38039 Kayseri (Turkey); Kandemirli, Fatma [Department of Chemistry, Nigde University, 41000 Nigde (Turkey)

2011-02-15

240

Eco-label - simple environmental choice / Andres Viia, Külliki Tafel  

Index Scriptorium Estoniae

Autorid selgitavad ökomärgistuse olemust ja vajalikkust tarbijate teavitamisel vähem keskkonda kahjustavatest toodetest ning teenustest. Lisatud näiteid regionaalsetest ja rahvuslikest ökomärkidest EL-is, tuntumatest ökomärkidest väljaspool Euroopat, hoiatavatest ja informatiivsetest keskkonnamärkidest ning libaökomärkidest. Vt. samas: North-East Estonia - a seat of an environment-friendly batteries' recycling

Viia, Andres

2003-01-01

 
 
 
 
241

Mediatransformasie dek die tafel vir ’n nuwe joernalistiek  

Directory of Open Access Journals (Sweden)

Full Text Available Media transformation sets the scene for a new journalismSince 1993 the South African media have been going through a period of fundamental transformation. This process has resulted in a phenomenon of black journalists and whites with credentials as anti-apartheid activists, moving into senior editorial positions at the South African Broadcasting Corporation (SABC as well as at newspapers. This article briefly describes the said transformational steps within the framework of existing media models, inter alia the developmental, social-responsibility and democratic-participatory models. Journalism covering the arts, culture and literature is thereby placed within a broader media context. It is concluded that the dominant media model(s will determine the kind of journalism we can expect in future.

J. D. Froneman

1997-05-01

242

Flow Forecasting in Drainage Systems with Extrapolated Radar Rainfall Data and Auto Calibration on Flow Observations  

DEFF Research Database (Denmark)

Forecasting of flows, overflow volumes, water levels, etc. in drainage systems can be applied in real time control of drainage systems in the future climate in order to fully utilize system capacity and thus save possible construction costs. An online system for forecasting flows and water levels in a small urban catchment has been developed. The forecast is based on application of radar rainfall data, which by a correlation based technique, is extrapolated with a lead time up to two hours. The runoff forecast in the drainage system is based on a fully distributed MOUSE model which is auto-calibrated on flow measurements in order to produce the best possible forecast for the drainage system at all times. The system shows great potential for the implementation of real time control in drainage systems and forecasting flows and water levels.

Thorndahl, SØren Liedtke; Grum, M.

2011-01-01

243

Hematological responses after inhaling 238PuO2: An extrapolation from beagle dogs to humans  

International Nuclear Information System (INIS)

The alpha emitter plutonium-238 (238Pu), which is produced in uranium-fueled, light-water reactors, is used as a thermoelectric power source for space applications. Inhalation of a mixed oxide form of Pu is the most likely mode of exposure of workers and the general public. Occupational exposures to 238PuO2 have occurred in association with the fabrication of radioisotope thermoelectric generators. Organs and tissue at risk for deterministic and stochastic effects of 238Pu-alpha irradiation include the lung, liver, skeleton, and lymphatic tissue. Little has been reported about the effects of inhaled 238PuO2 on peripheral blood cell counts in humans. The purpose of this study was to investigate hematological responses after a single inhalation exposure of Beagle dogs to alpha-emitting 238PuO2 particles and to extrapolate results to humans

244

Méthodologie de l'extrapolation des réacteurs chimiques Methodology for Scaling Up Chemical Reactors  

Directory of Open Access Journals (Sweden)

Full Text Available Après un exposé général relatif à la méthodologie du développement des procédés, applicable à l'extrapolation des réacteurs, est présenté un rapide examen critique des deux principales techniques mises en oeuvre, à savoir : - la théorie de la similitude ; - l'élaboration de modèles mathématiques. Deux exemples pratiques, relatifs aux réacteurs homogènes et aux réacteurs catalytiques à lit fixe et deux phases fluides, sont ensuite examinés à la lumière des considérations générales précédentes. After giving a general description of process-development methodology applicable to scaling up reactors, this article makes a quick critical examination of the two main techniques involved, i. e. : (a the theory of similarity, and (b the compiling of mathematical models. Two practical examples relating to homogeneous reactors and trickle-bed catalytic reactors are then examined in the light of the preceding general considerations.

Trambouze P.

2006-11-01

245

Statistical validation of engineering and scientific models : bounds, calibration, and extrapolation.  

Energy Technology Data Exchange (ETDEWEB)

Numerical models of complex phenomena often contain approximations due to our inability to fully model the underlying physics, the excessive computational resources required to fully resolve the physics, the need to calibrate constitutive models, or in some cases, our ability to only bound behavior. Here we illustrate the relationship between approximation, calibration, extrapolation, and model validation through a series of examples that use the linear transient convective/dispersion equation to represent the nonlinear behavior of Burgers equation. While the use of these models represents a simplification relative to the types of systems we normally address in engineering and science, the present examples do support the tutorial nature of this document without obscuring the basic issues presented with unnecessarily complex models.

Dowding, Kevin J.; Hills, Richard Guy (New Mexico State University, Las Cruces, NM)

2005-04-01

246

Modeling of systematic retention of beryllium in rats. Extrapolation to humans  

International Nuclear Information System (INIS)

In this work, we analyzed different approaches, assayed in order to numerically describe the systemic behaviour of Beryllium. The experimental results used in this work, were previously obtained by Furchner et al. (1973), using Sprague-Dawley rats, and other animal species. Furchner's work includes the obtained model for whole body retention in rats but not for each target organ. In this work we present the results obtained by modeling the kinetic behaviour of Beryllium in several target organs. The results of this kind of models were used in order to establish correlations among the estimated kinetic constants. The parameters of the model were extrapolated to humans and, finally, compared with other previously published

247

Quantifying regional changes in terrestrial carbon storage by extrapolation from local ecosystem models  

Energy Technology Data Exchange (ETDEWEB)

A general procedure for quantifying regional carbon dynamics by spatial extrapolation of local ecosystem models is presented Monte Carlo simulation to calculate the expected value of one or more local models, explicitly integrating the spatial heterogeneity of variables that influence ecosystem carbon flux and storage. These variables are described by empirically derived probability distributions that are input to the Monte Carlo process. The procedure provides large-scale regional estimates based explicitly on information and understanding acquired at smaller and more accessible scales.Results are presented from an earlier application to seasonal atmosphere-biosphere CO{sub 2} exchange for circumpolar ``subarctic`` latitudes (64{degree}N-90{degree}N). Results suggest that, under certain climatic conditions, these high northern ecosystems could collectively release 0.2 Gt of carbon per year to the atmosphere. I interpret these results with respect to questions about global biospheric sinks for atmospheric CO{sub 2} .

King, A W

1991-12-31

248

Upper bounds for the error in some interpolation and extrapolation designs  

CERN Document Server

This paper deals with probabilistic upper bounds for the error in functional estimation defined on some interpolation and extrapolation designs, when the function to estimate is supposed to be analytic. The error pertaining to the estimate may depend on various factors: the frequency of observations on the knots, the position and number of the knots, and also on the error committed when approximating the function through its Taylor expansion. When the number of observations is fixed, then all these parameters are determined by the choice of the design and by the choice estimator of the unknown function. The scope of the paper is therefore to determine a rule for the minimal number of observation required to achieve an upper bound of the error on the estimate with a given maximal probability.

Broniatowski, Michel; Di Battista, Marco; Leoni-Aubin, Samuela

2011-01-01

249

Extrapolation of lattice QCD results beyond the power-counting regime  

CERN Document Server

Resummation of the chiral expansion is necessary to make accurate contact with current lattice simulation results of full QCD. Resummation techniques including relativistic formulations of chiral effective field theory and finite-range regularization (FRR) techniques are reviewed, with an emphasis on using lattice simulation results to constrain the parameters of the chiral expansion. We illustrate how the chiral extrapolation problem has been solved and use FRR techniques to identify the power-counting regime (PCR) of chiral perturbation theory. To fourth-order in the expansion at the 1% tolerance level, we find $0 \\le m_\\pi \\le 0.18$ GeV for the PCR, extending only a small distance beyond the physical pion mass.

Leinweber, D B; Young, R D

2005-01-01

250

Integrated scenario with type-III ELMy H-mode edge: extrapolation to ITER  

International Nuclear Information System (INIS)

One of the most severe problems for fusion reactors is the power load on the plasma facing components. The challenge is to develop operation scenarios, which combine sufficient energy confinement with benign heat loads to the plasma facing components. The radiative type-III ELMy H-mode seems a possible solution for such an integrated ITER scenario. Nitrogen seeded type-III ELMy H-modes for the standard inductive scenario and the high beta stationary hybrid scenario are investigated with respect to their transient and steady-state power fluxes to the divertor, confinement properties, edge operational space, core operational space, plasma purity and MHD behaviour. A large database of highly radiative type-III ELMy H-modes on JET is used for extrapolations to ITER. On this basis the transient heat load should be acceptable for ITER. It was found that the scaling of the confinement time with respect to the ion gyroradius is close to the gyro-Bohm scaling. Scalings with respect to the plasma collisionality suggest that the confinement will be good enough for an ITER scenario at 17 MA with a power amplification factor (Q) of 10 and might be marginally good enough for a Q = 10 scenario at 15 MA. Those extrapolations are supported by simulations with an integrated core/edge model COREDIV. In addition the hybrid scenario with type-III edge localized modes has been proven to have improved edge conditions without any modification of the central plasma current profile, indicating it is compatible with a high beta operation for a steady-state ITER Q = 5 scenario.

251

Extrapolating glacier mass balance to the mountain range scale: the European Alps 1900–2100  

Directory of Open Access Journals (Sweden)

Full Text Available This study addresses the extrapolation of single glacier mass balance measurements to the mountain range scale and aims at deriving time series of area-averaged mass balance and ice volume change for all glaciers in the European Alps for the period 1900–2100. Long-term mass balance series for 50 Swiss glaciers based on a combination of field data and modelling, and WGMS data for glaciers in Austria, France and Italy are used. A complete glacier inventory is available for the year 2003. Mass balance extrapolation is performed based on (1 arithmetic averaging, (2 glacier hypsometry, and (3 multiple regression. Given a sufficient number of data series, multiple regression with variables describing glacier geometry performs best in reproducing observed spatial mass balance variability. Future mass changes are calculated by driving a combined model for mass balance and glacier geometry with GCM ensembles based on four emission scenarios. Mean glacier mass balance in the European Alps is ?0.32 ± 0.04 m w.e. a?1 in 1900–2011, and ?1 m w.e. a?1 over the last decade. Total ice volume change since 1900 is ?100 ± 13 km3; annual values vary between ?5.9 km3 (1947 and +3.9 km3 (1977. Mean mass balances are expected to be around ?1.3 m w.e. a?1 by 2050. Model results indicate a glacier area reduction to 4–18% relative to 2003 for the end of the 21st century.

M. Huss

2012-03-01

252

Torsional profile of 2,2,2-trifluoroethanol: A theoretical analysis with basis set extrapolation  

Science.gov (United States)

The conformational potential for rotation around the C bond C bond O bond H torsional angle of 2,2,2-trifluoroethanol (TFE) has been investigated at second-order Möller-Plesset (MP2) perturbation theory with two series of Dunning's correlation consistent basis sets, cc-pVNZ and aug-cc-pVNZ, N = D, T, Q, and 5. Single-point energy calculations with MP4(SDQ)/(aug-)cc-pVTZ and MP4(SDQT)/cc-pVTZ were also performed. It was found that the geometries of stationary points on this conformational profile are dependent on the basis set size, particularly the torsional angle of the gauche-isomer and the transition structure between the gauche- and anti-isomers (from 61° and 142°, respectively, at cc-pVDZ, to 65° and 149° at aug-cc-pVQZ), requiring at least a aug-cc-pVTZ basis set to be correctly optimized. Additionaly, an even lower barrier height (as low as 0.04 kcal/mol) than that previously calculated by Senent et al. for the conversion of anti-TFE to its more stable (by about 1.95 kcal/mol) gauche-conformer has been obtained, which reinforces the prediction that the main, if not the only, component of TFE in gas phase is its gauche-isomer. The MP2 data were also used in different schemes of basis set extrapolation. Unfortunately, maybe because third-order correlation energy contributions were not considered, these schemes have failed in providing suitable extrapolated energies.

de Amorim, Mauro B.

253

Generation of Co3O4 microparticles by solution combustion method and its Zn–Co3O4 composite thin films for corrosion protection  

International Nuclear Information System (INIS)

Graphical abstract: The pseudo-cubic cobalt oxide microparticles have been successfully synthesized by a solution combustion method using Co(NO3)2·6H2O (oxidizer) and dextrose (sugar; fuel). The as-synthesized Co3O4 microparticles are crystalline and Rietveld refinement of calcined samples exhibited cubic structure with space group of Fm3m (No. 227). The generated Co3O4 microparticles were used to fabricate Zn–Co3O4 composite thin films for corrosion protection. Highlights: ? Synthesis of pseudo-cubic Co3O4 microparticles by solution combustion method. ? As-prepared Co3O4 compounds are calcined and structurally characterized. ? Prepared Co3O4 are utilized for the fabrication of Zn–Co3O4 composite thin films. - Abstract: Microcrystalline cobalt oxide (Co3O4) powder was successfully synthesized by a simple, fast, economical and eco-friendly solution-combustion method. The as-synthesized powder was calcined for an hour at temperatures ranging from 100 to 900 °C. The crystallite size, morphology, and chemical state of synthesized powders were characterized by powder XRD, TG-DTA, XPS, SEM/EDAX, TEM and FT-IR spectral methods. The as-synthesized Co3O4 powder was single-crystalline and Rietveld refinement of calcined samples exhibited cf calcined samples exhibited cubic structure with space group of Fm3m (No. 227). The effect of calcination temperature on crystallite size and morphology was assessed. Scanning electron micrographs show a uniform, randomly oriented pseudo-cubic particle with porous like morphology and EDAX measurement showed its chemical composition. Thermal behavior of as-synthesized compound was examined. The TEM result revealed that, the particles are pseudo-cubic in nature with diameter of 0.2–0.6 ?m and a length of 0.9–1.2 ?m. The crystallite size increased with increase of calcination temperature. The synthesized Co3O4 powder was used to fabricate Zn–Co3O4 composite thin films and its corrosion behavior was analyzed by anodic polarization, tafel extrapolation and electrochemical impedance spectroscopy. The results indicate that the Zn–Co3O4 composite thin films have potential applications to corrosion protection.

254

Extrapolated experimental critical parameters of unreflected and steel-reflected massive enriched uranium metal spherical and hemispherical assemblies  

Energy Technology Data Exchange (ETDEWEB)

Sixty-nine critical configurations of up to 186 kg of uranium are reported from very early experiments (1960s) performed at the Rocky Flats Critical Mass Laboratory near Denver, Colorado. Enriched (93%) uranium metal spherical and hemispherical configurations were studied. All were thick-walled shells except for two solid hemispheres. Experiments were essentially unreflected; or they included central and/or external regions of mild steel. No liquids were involved. Critical parameters are derived from extrapolations beyond subcritical data. Extrapolations, rather than more precise interpolations between slightly supercritical and slightly subcritical configurations, were necessary because experiments involved manually assembled configurations. Many extrapolations were quite long; but the general lack of curvature in the subcritical region lends credibility to their validity. In addition to delayed critical parameters, a procedure is offered which might permit the determination of prompt critical parameters as well for the same cases. This conjectured procedure is not based on any strong physical arguments.

Rothe, R.E.

1997-12-01

255

Extrapolated experimental critical parameters of unreflected and steel-reflected massive enriched uranium metal spherical and hemispherical assemblies  

International Nuclear Information System (INIS)

Sixty-nine critical configurations of up to 186 kg of uranium are reported from very early experiments (1960s) performed at the Rocky Flats Critical Mass Laboratory near Denver, Colorado. Enriched (93%) uranium metal spherical and hemispherical configurations were studied. All were thick-walled shells except for two solid hemispheres. Experiments were essentially unreflected; or they included central and/or external regions of mild steel. No liquids were involved. Critical parameters are derived from extrapolations beyond subcritical data. Extrapolations, rather than more precise interpolations between slightly supercritical and slightly subcritical configurations, were necessary because experiments involved manually assembled configurations. Many extrapolations were quite long; but the general lack of curvature in the subcritical region lends credibility to their validity. In addition to delayed critical parameters, a procedure is offered which might permit the determination of prompt critical parameters as well for the same cases. This conjectured procedure is not based on any strong physical arguments

256

Characterization of an extrapolation chamber for low-energy X-rays: experimental and Monte Carlo preliminary results.  

Science.gov (United States)

The extrapolation chamber is a parallel-plate ionization chamber that allows variation of its air-cavity volume. In this work, an experimental study and MCNP-4C Monte Carlo code simulations of an ionization chamber designed and constructed at the Calibration Laboratory at IPEN to be used as a secondary dosimetry standard for low-energy X-rays are reported. The results obtained were within the international recommendations, and the simulations showed that the components of the extrapolation chamber may influence its response up to 11.0%. PMID:22182629

Neves, Lucio P; Silva, Eric A B; Perini, Ana P; Maidana, Nora L; Caldas, Linda V E

2012-07-01

257

The new track extrapolation package of the ATLAS tracking software in a case study of a high precision W mass measurement  

International Nuclear Information System (INIS)

Full text: The desired precision of 25 MeV for the W mass with the ATLAS detector is planed to be achieved by using the leptonic decay channel of the W : W ? l?, where l = e, ? . As the longitudinal momentum of the neutrino can not be measured, the measurement is done using the transverse momentum of lepton and neutrino, which is calculated through a recoil method. Results from CDF and D0 have shown that an unprecise knowledge of the total lepton energy and momentum scale is the dominating source of uncertainty of the W mass measurement. The knowledge of the lepton mass scale requires a deep understanding of the material in the ATLAS Inner Detector with a uncertainty of about 1 % which is of an order of magnitude better than in any comparable high energy physics experiment so far. In addition the magnetic field map has to be known with a precision of 0.1 %. This also requires tracking algorithms to process this detailed input. The methodology on how to achieve such a detailed description and its correct treatment including energy loss and multiple scattering effects during track extrapolation will be presented. In addition, results from the ATLAS Combined Testbeam 2004 using the new extrapolation scheme will be included into the presentation. (author)

258

Accelerating Monte Carlo molecular simulations by reweighting and reconstructing Markov chains: Extrapolation of canonical ensemble averages and second derivatives to different temperature and density conditions  

Science.gov (United States)

Accurate determination of thermodynamic properties of petroleum reservoir fluids is of great interest to many applications, especially in petroleum engineering and chemical engineering. Molecular simulation has many appealing features, especially its requirement of fewer tuned parameters but yet better predicting capability; however it is well known that molecular simulation is very CPU expensive, as compared to equation of state approaches. We have recently introduced an efficient thermodynamically consistent technique to regenerate rapidly Monte Carlo Markov Chains (MCMCs) at different thermodynamic conditions from the existing data points that have been pre-computed with expensive classical simulation. This technique can speed up the simulation more than a million times, making the regenerated molecular simulation almost as fast as equation of state approaches. In this paper, this technique is first briefly reviewed and then numerically investigated in its capability of predicting ensemble averages of primary quantities at different neighboring thermodynamic conditions to the original simulated MCMCs. Moreover, this extrapolation technique is extended to predict second derivative properties (e.g. heat capacity and fluid compressibility). The method works by reweighting and reconstructing generated MCMCs in canonical ensemble for Lennard-Jones particles. In this paper, system's potential energy, pressure, isochoric heat capacity and isothermal compressibility along isochors, isotherms and paths of changing temperature and density from the original simulated points were extrapolated. Finally, an optimized set of Lennard-Jones parameters (?, ?) for single site models were proposed for methane, nitrogen and carbon monoxide.

Kadoura, Ahmad; Sun, Shuyu; Salama, Amgad

2014-08-01

259

Beagle: an appropriate experimental animal for extrapolating the organ distribution pattern of Th in humans  

International Nuclear Information System (INIS)

The concentrations and the organ distribution patterns of 228Th, 230Th and 232Th in two 9-y-old dogs of our beagle colony were determined. The dogs were exposed only to background environmental levels of Th isotopes through ingestion (food and water) and inhalation as are humans. The organ distribution patterns of the isotopes in the beagles were compared to the organ distribution patterns in humans to determine if it is appropriate to extrapolate the beagle organ burden data to humans. Among soft tissues, only the lungs, lymph nodes, kidney and liver, and skeleton contained measurable amounts of Th isotopes. The organ distribution pattern of Th isotopes in humans and dog are similar, the majority of Th being in the skeleton of both species. The average skeletal concentrations of 228Th in dogs were 30 to 40 times higher than the average skeletal concentrations of the parent 232Th, whereas the concentration of 228Th in human skeleton was only four to five times higher than 232Th. This suggests that dogs have a higher intake of 228Ra through food than humans. There is a similar trend in the accumulations of 232Th, 230Th and 228Th in the lungs of dog and humans. The percentages of 232Th, 230Th and 228Th in human lungs are 26, 9.7 and 4.8, respectively, compared to 4.2, 2.6 and 0.48, respectively, in dog lungs. The larger percentages of Th isotopes in human lungs may be due simply to the longer life span of humans. If the burdens of Th isotopes in human lungs are normalized to an exposure time of 9.2 y (mean age of dogs at the time of sacrifice), the percent burden of 232Th, 230Th and 228Th in human lungs are estimated to be 3.6, 1.3 and 0.66, respectively. These results suggest that the beagle may be an appropriate experimental animal for extrapolating the organ distribution pattern of Th in humans

260

The risk of extrapolation in neuroanatomy: the case of the mammalian vomeronasal system  

Directory of Open Access Journals (Sweden)

Full Text Available The sense of smell plays a crucial role in mammalian social and sexual behaviour, identification of food, and detection of predators. Nevertheless, mammals vary in their olfactory ability. One reason for this concerns the degree of development of their pars basalis rhinencephali, an anatomical feature that has has been considered in classifying this group of animals as macrosmatic, microsmatic or anosmatic. In mammals, different structures are involved in detecting odours: the main olfactory system, the vomeronasal system (VNS, and two subsystems, namely the ganglion of Grüneberg and the septal organ. Here, we review and summarise some aspects of the comparative anatomy of the VNS and its putative relationship to other olfactory structures. Even in the macrosmatic group, morphological diversity is an important characteristic of the VNS, specifically of the vomeronasal organ and the accessory olfactory bulb. We conclude that it is a big mistake to extrapolate anatomical data of the VNS from species to species, even in the case of relatively close evolutionary proximity between them. We propose to study other mammalian VNS than those of rodents in depth as a way to clarify its exact role in olfaction. Our experience in this field leads us to hypothesise that the VNS, considered for all mammalian species, could be a system undergoing involution or regression, and could serve as one more integrated olfactory subsystem.

IgnacioSalazar

2009-10-01

 
 
 
 
261

Physiological modeling and extrapolation of pharmacokinetic interactions from binary to more complex chemical mixtures.  

Science.gov (United States)

The available data on binary interactions are yet to be considered within the context of mixture risk assessment because of our inability to predict the effect of a third or a fourth chemical in the mixture on the interacting binary pairs. Physiologically based pharmacokinetic (PBPK) models represent a potentially useful framework for predicting the consequences of interactions in mixtures of increasing complexity. This article highlights the conceptual basis and validity of PBPK models for extrapolating the occurrence and magnitude of interactions from binary to more complex chemical mixtures. The methodology involves the development of PBPK models for all mixture components and interconnecting them at the level of the tissue where the interaction is occurring. Once all component models are interconnected at the binary level, the PBPK framework simulates the kinetics of all mixture components, accounting for the interactions occurring at various levels in more complex mixtures. This aspect was validated by comparing the simulations of a binary interaction-based PBPK model with experimental data on the inhalation kinetics of m-xylene, toluene, ethyl benzene, dichloromethane, and benzene in mixtures of varying composition and complexity. The ability to predict the kinetics of chemicals in complex mixtures by accounting for binary interactions alone within a PBPK model is a significant step toward the development of interaction-based risk assessment for chemical mixtures. PMID:12634130

Krishnan, Kannan; Haddad, Sami; Béliveau, Martin; Tardif, Robert

2002-12-01

262

Can the Thermodynamic Hodgkin-Huxley Model of Voltage-Dependent Conductance Extrapolate for Temperature?  

Directory of Open Access Journals (Sweden)

Full Text Available Hodgkin and Huxley (H-H fitted their model of voltage-dependent conductances to experimental data using empirical functions of voltage. The thermodynamic H-H model of voltage dependent conductances is more physically plausible, as it constrains and parameterises its empirical fit by assuming that ion channel transition rates depend exponentially on a free energy barrier that in turn, linearly or non-linearly, depends on voltage. The original H-H model contains no explicit temperature terms and requires Q10 factors to describe data at different temperatures. The thermodynamic H-H model does have explicit terms for temperature. Do these endow the model with extrapolation for temperature? We utilised voltage clamp data for a voltage-gated K+ current, recorded at three different temperatures. The thermodynamic H-H model’s free parameters were fitted (Marquardt-Levenberg algorithm to a data set recorded at one (or more temperature(s. Then we assessed whether it could describe another data set, recorded at a different temperature, with these same free parameter values and its temperature terms set to the new temperature. We found that it could not.

Michael D. Forrest

2014-05-01

263

Root crack sizing using phased array inspections and autoregressive spectral extrapolation signal processing  

Science.gov (United States)

Phased array inspection was conducted on a V-butt welded steel sample with multiple shallow flaws of varying depths. The inspection measurements were processed using Wiener filtering and Autoregressive Spectral Extrapolation (AS) to enhance the signals. Phased array inspections were conducted using multiple phased array probes of varying nominal central frequencies (2.25, 4, 5 and 10 MHz). This paper describes the measured results, which show high accuracy, typically in the range of 0.1-0.2 mm. The results concluded that: 1. There was no statistical difference between the calculated flaw depths from phased array inspections at different flaw tip angles. 2. There was no statistical difference in flaw depths calculated using phased array data collected from either side of the weld. 3. Flaws with depths less than the estimated probe signal shear wavelength could not be sized. 4. Finally, there was no statistical difference in the calculated flaw depths using phased array probes with different sampling frequencies and destructive measurements of the flaws.

Caldwell, J.; Shakibi, B.; Moles, M.; Sinclair, A. N.

2013-01-01

264

Natural basaltic glass analogue for the long-term extrapolation of nuclear waste glass aging  

International Nuclear Information System (INIS)

Increased confidence is provided to the extrapolation of long-term waste form behavior by comparing the alteration of experimentally aged natural basaltic glass to the condition of the same glass as it has been geologically aged. The similarity between the laboratory and geologic alterations indicates that important aging variables have been identified and incorporated into the laboratory experiments. This provides credibility to the long-term predictions made for waste form borosilicate glasses using similar experimental procedures. In addition, these experiments have demonstrated that the aging processes for natural basaltic glass are relevant to the alteration of nuclear waste glasses, as both appear to react via similar processes. The alteration of a synthetic basaltic glass was measured in MCC-1 tests done at 900C, a SA/V of 0.1 cm-1 and time periods up to 182 days. Tests were also done using (1) MCC-2 procedures at 1900C, a SA/V of 0.1 cm-1 and time periods up to 91 days and (2) hydration tests in saturated water vapor at 2400C, a SA/V of approx. 106 cm-1, and time periods up to 63 days. These results are compared to alteration observed in natural basaltic glasses of great age. 6 references, 6 figures, 1 table

265

Kinetics of HMX and CP Decomposition and Their Extrapolation for Lifetime Assessment  

Energy Technology Data Exchange (ETDEWEB)

Decomposition kinetics are determined for HMX (nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) and CP (2-(5-cyanotetrazalato) pentaammine cobalt (III) perchlorate) separately and together. For high levels of thermal stress, the two materials decompose faster as a mixture than individually. This effect is observed both in high-temperature thermal analysis experiments and in long-term thermal aging experiments. An Arrhenius plot of the 10% level of HMX decomposition by itself from a diverse set of experiments is linear from 120 to 260 C, with an apparent activation energy of 165 kJ/mol. Similar but less extensive thermal analysis data for the mixture suggests a slightly lower activation energy for the mixture, and an analogous extrapolation is consistent with the amount of gas observed in the long-term detonator aging experiments, which is about 30 times greater than expected from HMX by itself for 50 months at 100 C. Even with this acceleration, however, it would take {approx}10,000 years to achieve 10% decomposition at {approx}30 C. Correspondingly, negligible decomposition is predicted by this kinetic model for a few decades aging at temperatures slightly above ambient. This prediction is consistent with additional sealed-tube aging experiments at 100-120 C, which are estimated to have an effective thermal dose greater than that from decades of exposure to temperatures slightly above ambient.

Burnham, A K; Weese, R K; Andrzejewski, W J

2004-11-18

266

Employing Measures of Heterogeneity and an Object-Based Approach to Extrapolate Tree Species Distribution Data  

Directory of Open Access Journals (Sweden)

Full Text Available Information derived from high spatial resolution remotely sensed data is critical for the effective management of forested ecosystems. However, high spatial resolution data-sets are typically costly to acquire and process and usually provide limited geographic coverage. In contrast, moderate spatial resolution remotely sensed data, while not able to provide the spectral or spatial detail required for certain types of products and applications, offer inexpensive, comprehensive landscape-level coverage. This study assessed using an object-based approach to extrapolate detailed tree species heterogeneity beyond the extent of hyperspectral/LiDAR flightlines to the broader area covered by a Landsat scene. Using image segments, regression trees established ecologically decipherable relationships between tree species heterogeneity and the spectral properties of Landsat segments. The spectral properties of Landsat bands 4 (i.e., NIR: 0.76–0.90 µm, 5 (i.e., SWIR: 1.55–1.75 µm and 7 (SWIR: 2.08–2.35 µm were consistently selected as predictor variables, explaining approximately 50% of variance in richness and diversity. Results have important ramifications for ongoing management initiatives in the study area and are applicable to wide range of applications.

Trevor G. Jones

2014-07-01

267

Interpolating and Extrapolating Contaminant Concentrations from Monitor Wells to Model Grids for Fate-and-Transport Calculations  

Energy Technology Data Exchange (ETDEWEB)

Geostatistical interpolation of groundwater characterization data to visualize contaminant distributions in three dimensions is often hindered by the sparse distribution of samples relative to the size of the plume and scale of heterogeneities. Typically, placement of expensive monitoring wells is guided by the conceptualized plume rather than geostatistical considerations, focusing on contaminated areas rather than thoroughly gridding the plume boundary. The resulting data sets require careful analysis in order to produce plausible plume shells. A purely geostatistical approach is usually impractical; kriging parameters based on the observed data structure can extrapolate contamination far beyond the demonstrated extent of the plume. When more appropriate kriging parameters are selected, holes often occur in the interpolated distribution because realistic kriging ranges may not bridge large gaps between data points. Such artifacts obscure the probable location of the plume boundary and distort the contaminant distribution, obstructing quantitative modeling of remedial strategies. Two methods of constraining kriging can successfully eliminate these geostatistical artifacts. Laterally, the plume boundary may be controlled using a manually constructed mask that delineates the plan-view extent of the plume. After kriging, the mask is used to set all grid cells outside of the plume to a concentration of zero. Use of non-zero control points is a more refined but laborious approach that also bridges data gaps within the body of a plume and permits use of tighter kriging parameters. These can be obtained by manual linear interpolation between measured samples, or derived from historical data migrated along flow paths while accounting for all attenuative processes. Masking and use of non-zero control points result in a plume shell that reflects the intuition and professional judgment of the hydrologist, and can be interpolated automatically to any desired grid, providing initial conditions for fate-and-transport simulations. Error maps are a valuable aid in assessing data density, identifying areas that require additional sampling, or that must be filled by control points, if additional sampling is impractical.

Ward, D. B.; Clement, P.; Bostick, K.

2002-02-26

268

Characterization and application of two extrapolation chambers in standard X radiation beams; Caracterizacao e aplicacao de duas camaras de extrapolacao em feixes padronizados de radiacao X  

Energy Technology Data Exchange (ETDEWEB)

The extrapolation chambers are ionization chambers with variable volume, and they are mainly utilized as beta radiation detectors. In this work two extrapolation chambers were characterized, a commercial PTW extrapolation chamber and another extrapolation chamber developed at the Calibration Laboratory of IPEN, for application as reference systems in mammography, conventional diagnostic radiology and radiotherapy beams. The results obtained from the characterization tests of the chamber response: leakage current, short- and medium terms stability, determination of the saturation currents and the ion collection efficiencies, angular and energy dependence, show that these extrapolation chambers may be utilized for low-energy X radiation beam dosimetry. The transmission factors in tissue and the calibration factors were also determined for all cited radiation qualities. Finally, a procedure was established for calibration of radiation detectors in standard X radiation beams, using the extrapolation chambers. (author)

Silva, Eric Alexandre Brito da

2011-07-01

269

EVALUATION OF THE EFFICACY OF EXTRAPOLATION POPULATION MODELING TO PREDICT THE DYNAMICS OF AMERICAMYSIS BAHIA POPULATIONS IN THE LABORATORY  

Science.gov (United States)

An age-classified projection matrix model has been developed to extrapolate the chronic (28-35d) demographic responses of Americamysis bahia (formerly Mysidopsis bahia) to population-level response. This study was conducted to evaluate the efficacy of this model for predicting t...

270

DOSE-RESPONSE BEHAVIOR OF ANDROGENIC AND ANTIANDROGENIC CHEMICALS: IMPLICATIONS FOR LOW-DOSE EXTRAPOLATION AND CUMULATIVE TOXICITY  

Science.gov (United States)

DOSE-RESPONSE BEHAVIOR OF ANDROGENIC AND ANTIANDROGENIC CHEMICALS: IMPLICATIONS FOR LOW-DOSE EXTRAPOLATION AND CUMULATIVE TOXICITY. LE Gray Jr, C Wolf, J Furr, M Price, C Lambright, VS Wilson and J Ostby. USEPA, ORD, NHEERL, EB, RTD, RTP, NC, USA. Dose-response behavior of a...

271

Validity of extrapolated response dose as clinical prognostic indicator for incidence of spinal cord myelitis in altered fractionation  

International Nuclear Information System (INIS)

The aim of this study was to test the validity of extrapolated response dose (ERD) of linear quadratic model for altered fractionation schedules to the spinal cord using compiled clinical literature data and clinically reported data of spinal cord myelitis for altered fractionation

272

Multiple time step molecular dynamics in the optimized isokinetic ensemble steered with the molecular theory of solvation: Accelerating with advanced extrapolation of effective solvation forces  

International Nuclear Information System (INIS)

We develop efficient handling of solvation forces in the multiscale method of multiple time step molecular dynamics (MTS-MD) of a biomolecule steered by the solvation free energy (effective solvation forces) obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model complemented with the Kovalenko-Hirata closure approximation). To reduce the computational expenses, we calculate the effective solvation forces acting on the biomolecule by using advanced solvation force extrapolation (ASFE) at inner time steps while converging the 3D-RISM-KH integral equations only at large outer time steps. The idea of ASFE consists in developing a discrete non-Eckart rotational transformation of atomic coordinates that minimizes the distances between the atomic positions of the biomolecule at different time moments. The effective solvation forces for the biomolecule in a current conformation at an inner time step are then extrapolated in the transformed subspace of those at outer time steps by using a modified least square fit approach applied to a relatively small number of the best force-coordinate pairs. The latter are selected from an extended set collecting the effective solvation forces obtained from 3D-RISM-KH at outer time steps over a broad time interval. The MTS-MD integration with effective solvation forces obtained by converging 3D-RISM-KH at outer time steps and applying ASFE at inner time steps is stabilized by employing the optimized isokinetic Nosé-Hoover chain (OIN) ensemble. Compared to the previous extrapolation schemes used in combination with the Langevin thermostat, the ASFE approach substantially improves the accuracy of evaluation of effective solvation forces and in combination with the OIN thermostat enables a dramatic increase of outer time steps. We demonstrate on a fully flexible model of alanine dipeptide in aqueous solution that the MTS-MD/OIN/ASFE/3D-RISM-KH multiscale method of molecular dynamics steered by effective solvation forces allows huge outer time steps up to tens of picoseconds without affecting the equilibrium and conformational properties, and thus provides a 100- to 500-fold effective speedup in comparison to conventional MD with explicit solvent. With the statistical-mechanical 3D-RISM-KH account for effective solvation forces, the method provides efficient sampling of biomolecular processes with slow and/or rare solvation events such as conformational transitions of hydrated alanine dipeptide with the mean life times ranging from 30 ps up to 10 ns for “flip-flop” conformations, and is particularly beneficial for biomolecular systems with exchange and localization of solvent and ions, ligand binding, and molecular recognition

273

Multiple time step molecular dynamics in the optimized isokinetic ensemble steered with the molecular theory of solvation: Accelerating with advanced extrapolation of effective solvation forces  

Science.gov (United States)

We develop efficient handling of solvation forces in the multiscale method of multiple time step molecular dynamics (MTS-MD) of a biomolecule steered by the solvation free energy (effective solvation forces) obtained from the 3D-RISM-KH molecular theory of solvation (three-dimensional reference interaction site model complemented with the Kovalenko-Hirata closure approximation). To reduce the computational expenses, we calculate the effective solvation forces acting on the biomolecule by using advanced solvation force extrapolation (ASFE) at inner time steps while converging the 3D-RISM-KH integral equations only at large outer time steps. The idea of ASFE consists in developing a discrete non-Eckart rotational transformation of atomic coordinates that minimizes the distances between the atomic positions of the biomolecule at different time moments. The effective solvation forces for the biomolecule in a current conformation at an inner time step are then extrapolated in the transformed subspace of those at outer time steps by using a modified least square fit approach applied to a relatively small number of the best force-coordinate pairs. The latter are selected from an extended set collecting the effective solvation forces obtained from 3D-RISM-KH at outer time steps over a broad time interval. The MTS-MD integration with effective solvation forces obtained by converging 3D-RISM-KH at outer time steps and applying ASFE at inner time steps is stabilized by employing the optimized isokinetic Nosé-Hoover chain (OIN) ensemble. Compared to the previous extrapolation schemes used in combination with the Langevin thermostat, the ASFE approach substantially improves the accuracy of evaluation of effective solvation forces and in combination with the OIN thermostat enables a dramatic increase of outer time steps. We demonstrate on a fully flexible model of alanine dipeptide in aqueous solution that the MTS-MD/OIN/ASFE/3D-RISM-KH multiscale method of molecular dynamics steered by effective solvation forces allows huge outer time steps up to tens of picoseconds without affecting the equilibrium and conformational properties, and thus provides a 100- to 500-fold effective speedup in comparison to conventional MD with explicit solvent. With the statistical-mechanical 3D-RISM-KH account for effective solvation forces, the method provides efficient sampling of biomolecular processes with slow and/or rare solvation events such as conformational transitions of hydrated alanine dipeptide with the mean life times ranging from 30 ps up to 10 ns for "flip-flop" conformations, and is particularly beneficial for biomolecular systems with exchange and localization of solvent and ions, ligand binding, and molecular recognition.

Omelyan, Igor; Kovalenko, Andriy

2013-12-01

274

The cerebellum and visual perceptual learning: evidence from a motion extrapolation task.  

Science.gov (United States)

Visual perceptual learning is widely assumed to reflect plastic changes occurring along the cerebro-cortical visual pathways, including at the earliest stages of processing, though increasing evidence indicates that higher-level brain areas are also involved. Here we addressed the possibility that the cerebellum plays an important role in visual perceptual learning. Within the realm of motor control, the cerebellum supports learning of new skills and recalibration of motor commands when movement execution is consistently perturbed (adaptation). Growing evidence indicates that the cerebellum is also involved in cognition and mediates forms of cognitive learning. Therefore, the obvious question arises whether the cerebellum might play a similar role in learning and adaptation within the perceptual domain. We explored a possible deficit in visual perceptual learning (and adaptation) in patients with cerebellar damage using variants of a novel motion extrapolation, psychophysical paradigm. Compared to their age- and gender-matched controls, patients with focal damage to the posterior (but not the anterior) cerebellum showed strongly diminished learning, in terms of both rate and amount of improvement over time. Consistent with a double-dissociation pattern, patients with focal damage to the anterior cerebellum instead showed more severe clinical motor deficits, indicative of a distinct role of the anterior cerebellum in the motor domain. The collected evidence demonstrates that a pure form of slow-incremental visual perceptual learning is crucially dependent on the intact cerebellum, bearing the notion that the human cerebellum acts as a learning device for motor, cognitive and perceptual functions. We interpret the deficit in terms of an inability to fine-tune predictive models of the incoming flow of visual perceptual input over time. Moreover, our results suggest a strong dissociation between the role of different portions of the cerebellum in motor versus non-motor functions, with only the posterior lobe being responsible for learning in the perceptual domain. PMID:24959702

Deluca, Cristina; Golzar, Ashkan; Santandrea, Elisa; Lo Gerfo, Emanuele; Ešto?inová, Jana; Moretto, Giuseppe; Fiaschi, Antonio; Panzeri, Marta; Mariotti, Caterina; Tinazzi, Michele; Chelazzi, Leonardo

2014-09-01

275

Deposition of inhaled radionuclides in bronchial airways: Implications for extrapolation modeling  

International Nuclear Information System (INIS)

The laboratory rat has frequently been used as a human surrogate to estimate potential health effects following the inhalation of radioactive aerosol particles. Interspecies differences in biological response are commonly related to interspecies differences in particle deposition efficiencies. In addition, the documented site selectivity of bronchial carcinomas suggests that localized particle deposition patterns within bronchial airway bifurcations may have important implications for inhalation risk assessments. Interspecies differences in particle deposition patterns may be related primarily to differences in airway morphometries. Thus the validity of extrapolating rat deposition data to human inhalation conditions depends on their morphometric similarities and differences. It is well known that there are significant structural differences between the human - rather symmetric - and the rat - monopodial - airway systems. In the present approach, we focus on localized deposition patterns and deposition efficiencies in selected asymmetric bronchial airway bifurcations, whose diameters, lengths and branching angles were derived from the stochastic airway models of human and rat lungs (Koblinger and Hofmann, 1985;1988), which are based on the morphometric data of Raabe et al. (1976). The effects of interspecies differences in particle deposition patterns are explored in this study for two asymmetric bifurcation geometries in segmental bronchi and terminal bronchioles of both the human and rat lungs at different particle sizes. In order to examine the effect of flow rate on particle deposition in the human lung, we selected two different minute volumes, i.e., 10 and 60 1 min-1 , which are representative of low and heavy physical activity breathing conditions. In the case of the rat we used a minute volume of 0.234 1 min-1 (Hofmann et al., 1993)

276

Cross-Species Extrapolation of Prediction Models for Cadmium Transfer from Soil to Corn Grain  

Science.gov (United States)

Cadmium (Cd) is a highly toxic heavy metal for both plants and animals. The presence of Cd in agricultural soils is of great concern regarding its transfer in the soil-plant system. This study investigated the transfer of Cd (exogenous salts) from a wide range of Chinese soils to corn grain (Zhengdan 958). Through multiple stepwise regressions, prediction models were developed, with the combination of Cd bioconcentration factor (BCF) of Zhengdan 958 and soil pH, organic matter (OM) content, and cation exchange capacity (CEC). Moreover, these prediction models from Zhengdan 958 were applied to other non-model corn species through cross-species extrapolation approach. The results showed that the pH of the soil was the most important factor that controlled Cd uptake and lower pH was more favorable for Cd bioaccumulation in corn grain. There was no significant difference among three prediction models in the different Cd levels. When the prediction models were applied to other non-model corn species, the ratio ranges between the predicted BCF values and the measured BCF values were within an interval of 2 folds and close to the solid line of 1?1 relationship. Furthermore, these prediction models also reduced the measured BCF intra-species variability for all non-model corn species. Therefore, the prediction models established in this study can be applied to other non-model corn species and be useful for predicting the Cd bioconcentration in corn grain and assessing the ecological risk of Cd in different soils. PMID:24324636

Yang, Hua; Li, Zhaojun; Lu, Lu; Long, Jian; Liang, Yongchao

2013-01-01

277

A new approach to bridge the effect of organofacies variations on kinetic modelling and geological extrapolations  

Energy Technology Data Exchange (ETDEWEB)

Reliable prediction of petroleum formation is impeded by significant variations in organofacies that result from varying conditions during source rock deposition. Basin simulation programs can model lateral variations but are limited in their ability to account for vertical variations due to the impact on computation time and lack of representative kinetic parameters. Here we present a model that merges the petroleum formation characteristics of different organofacies, vertically distributed in a heterogeneous source rock, prior to kinetic modelling. This approach allows the evaluation of one single overall kinetic model that accounts for the different petroleum generation characteristics of a variety of organofacies preserved in a source rock and balance the different petroleum formation processes according to their importance within the different organofacies. Bulk petroleum generation kinetics were determined on eleven Draupne Formation samples taken from a well in the Tampen Spur area using programmed temperature open system pyrolysis at 0.1, 0.7 and 5.0 K/min. The samples covered the entire Draupne Formation from its bottom to its top in the studied well. Individual measurements taken at the same heating rate were summed to one pyrolysis yield curve and normalized to the average Rock-Eval S2 value. The three summed curves were then used as input to determine a kinetic model that is representative of the Draupne Formation in this well. Enhanced kinetic modelling was applied in order to account for the expected variations of frequency factors. After geological extrapolation, the resulting kinetic model represents the petroleum generation characteristics of the entire Draupne Formation in the study area, accounting for the variability in source potential across organofacies. (author)

Dieckmann, V.; Keym, M. [GeoForschungszentrum Potsdam (Germany)

2006-06-15

278

Extrapolation of short term observations to time periods relevant to the isolation of long lived radioactive waste. Results of a co-ordinated research project 1995-2000  

International Nuclear Information System (INIS)

This report addresses safety analysis of the whole repository life-cycle that may require long term performance assessment of its components and evaluation of potential impacts of the facility on the environment. Generic consideration of procedures for the development of predictive tools are completed by detailed characterization of selected principles and methods that were applied and presented within the co-ordinated research project (CRP). The project focused on different approaches to extrapolation, considering radionuclide migration/sorption, physical, geochemical and geotechnical characteristics of engineered barriers, irradiated rock and backfill performance, and on corrosion of metallic and vitreous materials. This document contains a comprehensive discussion of the overall problem and the practical results of the individual projects preformed within the CRP. Each of the papers on the individual projects has been indexed separately

279

A fish of many scales: extrapolating sublethal pesticide exposures to the productivity of wild salmon populations.  

Science.gov (United States)

For more than a decade, numerous pesticides have been detected in river systems of the western United States that support anadromous species of Pacific salmon and steelhead. Over the same interval, several declining wild salmon populations have been listed as either threatened or endangered under the U.S. Endangered Species Act (ESA). Because pesticides occur in surface waters that provide critical habitat for ESA-listed stocks, they are an ongoing concern for salmon conservation and recovery throughout California and the Pacific Northwest. Because pesticide exposures are typically sublethal, a key question is whether toxicological effects at (or below) the scale of the individual animal ultimately reduce the productivity and recovery potential of wild populations. In this study we evaluate how the sublethal impacts of pesticides on physiology and behavior can reduce the somatic growth of juvenile chinook salmon (Oncorhynchus tshawytscha) and, by extension, subsequent size-dependent survival when animals migrate to the ocean and overwinter in their first year. Our analyses focused on the organophosphate and carbamate classes of insecticides. These neurotoxic chemicals have been widely detected in aquatic environments. They inhibit acetylcholinesterase, an enzyme in the salmon nervous system that regulates neurotransmitter-mediated signaling at synapses. Based on empirical data, we developed a model that explicitly links sublethal reductions in acetylcholinesterase activity to reductions in feeding behavior, food ration, growth, and size at migration. Individual size was then used to estimate size-dependent survival during migration and transition to the sea. Individual survival estimates were then integrated into a life-history population projection matrix and used to calculate population productivity and growth rate. Our results indicate that short-term (i.e., four-day) exposures that are representative of seasonal pesticide use may be sufficient to reduce the growth and size at ocean entry of juvenile chinook. The consequent reduction in individual survival over successive years reduces the intrinsic productivity (lambda) of a modeled ocean-type chinook population. Overall, we show that exposures to common pesticides may place important constraints on the recovery of ESA-listed salmon species, and that simple models can be used to extrapolate toxicological impacts across several scales of biological complexity. PMID:20014574

Baldwin, David H; Spromberg, Julann A; Collier, Tracy K; Scholz, Nathaniel L

2009-12-01

280

Characterization of a extrapolation chamber in standard X-ray beam, radiodiagnosis level; Caracterizacao de uma camara de extrapolacao em feixes padroes de raios X, nivel radiodiagnostico  

Energy Technology Data Exchange (ETDEWEB)

The extrapolation chamber is a ionization chamber used for detection low energy radiation and can be used as an standard instrument for beta radiation beams. This type of ionization chamber have as main characteristic the variation of sensible volume. This paper performs a study of characterization of a PTW commercial extrapolation chamber, in the energy interval of the qualities of conventional radiodiagnostic

Silva, Eric A.B. da; Caldas, Linda V.E., E-mail: ebrito@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-10-26

 
 
 
 
281

Some new aspects of comparison of cell survival-dose curves (statistical analysis and extrapolation number modification factor)  

International Nuclear Information System (INIS)

The formulae are presented permitting to calculate, by the regression analysis, the values of n, D0, Dsub(q1, D37, D50, etc., and D0MF,Dsub(q)MF, D37MF, D50MF, etc., and their errors. The ratios between different doses and DMF were determined. It seemed expedient to use the variance analysis in determining the linearity of exponential parts of the dose-survival curves in the lg S-D coordinates, and the parallelism between them. Eight variants of changes in the main parameters of the dose-survival curves are discussed. New indices are proposed: the extrapolation number modification factor and the extrapolation number logarithm modification factor; the expedience of using thereof is reasoned

282

Extrapolation to a demonstration reactor from the ITER and advanced physics and materials data bases. Demo and commercial fusion reactors extrapolated from the ITER and advanced physics and materials data bases. Radioactive waste produced by demo and commercial fusion reactors extrapolated from ITER and advanced data bases  

International Nuclear Information System (INIS)

The report contains 2 papers. In the first paper, the characteristics of demonstration (DEMO) reactors that could be conservatively extrapolated from the data base that will be provided by ITER and its supporting R ampersand D and from a data base supplemented by advanced physics and advanced materials R ampersand D programs are identified. In the second paper, the radioactive wastes that would be produced in demonstration (DEMO) and commercial (CFR) fusion reactors which could be extrapolated from the design data base that will be provided by ITER and its supporting R ampersand D and from a design data base supplemented by advanced physics and advanced materials R ampersand D programs are identified and characterized in terms of a number of possible criteria for near-surface burial. The results indicate that there is a possibility that all fusion wastes could satisfy a 'low level' waste criterion for 'near-surface' burial

283

Interferometric synthetic aperture radar deformation data used to interpolate and extrapolate hydraulic head time-series  

Science.gov (United States)

A 2004 court decision established that hydraulic head levels within the confined aquifer system of the San Luis Valley (SLV), Colorado be maintained within the range experienced in the years between 1978 and 2000. The current groundwater flow model for this area is not able to predict hydraulic head accurately in the confined aquifer system due to a dearth of calibration points, i.e., hydraulic head measurements, during the time period of interest. The work presented here investigates the extent to which spatially and temporally dense measurements of deformation from Interferometric Synthetic Aperture Radar (InSAR) data could be used to interpolate and extrapolate temporal and spatial gaps in the hydraulic head dataset by performing a calibration at the well locations. We first predicted the magnitude of the seasonal deformation at the confined aquifer well locations by using aquifer thickness/lithology information from well logs and estimates of the aquifer compressibility from the literature. At 11 well locations the seasonal magnitude of the deformation was sufficiently large so as to be reliably measured with InSAR, given the accepted level of uncertainty of the measurement (~ 5 mm). Previous studies in arid or urban areas have shown that high quality InSAR deformation measurements are often collocated with hydraulic head measurements at monitoring wells, making such a calibration approach relatively straightforward. In contrast, the SLV is an agricultural area where many factors, e.g. crop growth, can seriously degrade the quality of the InSAR data. We used InSAR data from the ERS-1 and ERS-2 satellites, which have a temporal sampling of 35 days and a spatial sampling on the order of 10's of meters, and found that the InSAR data were not of sufficiently high quality at any of the 11 selected well locations. Hence, we used geostatistical techniques to analyze the high quality InSAR deformation data elsewhere in the scene and to estimate the deformation at the selected well locations. At the 11 locations we estimated the compressibility parameter that relates the deformation and the hydraulic head. We found that this calibration was effective at 3 of the well locations where the magnitude of the seasonal deformation was > 3 cm, well above the uncertainty of the InSAR measurement. We then estimated the hydraulic head prior to and within the temporal sampling window of the hydraulic head measurements at the 3 well locations. We found that 59% of the InSAR-predicted hydraulic head values agree with the measured hydraulic head values, within the uncertainty of the data. Given our success in extending the hydraulic head data temporally, the next step in our research is to use InSAR data to interpolate spatially between hydraulic head measurements at field sites where the magnitude of the deformation is large enough to be accurately measured by InSAR.

Reeves, J. A.; Knight, R. J.; Zebker, H. A.; Kitanidis, P. K.; Schreuder, W. A.

2013-12-01

284

Diagnostic, Explanatory, and Detection Models of Munchausen by Proxy: Extrapolations from Malingering and Deception  

Science.gov (United States)

Objective: The overriding objective is a critical examination of Munchausen syndrome by proxy (MSBP) and its closely-related alternative, factitious disorder by proxy (FDBP). Beyond issues of diagnostic validity, assessment methods and potential detection strategies are explored. Methods: A painstaking analysis was conducted of the MSBP and FDBP…

Rogers, Richard

2004-01-01

285

Application of physiologically-based toxicokinetic modelling in oral-to-dermal extrapolation of threshold doses of cosmetic ingredients.  

Science.gov (United States)

The application of physiologically based toxicokinetic (PBTK) modelling in route-to-route (RtR) extrapolation of three cosmetic ingredients: coumarin, hydroquinone and caffeine is shown in this study. In particular, the oral no-observed-adverse-effect-level (NOAEL) doses of these chemicals are extrapolated to their corresponding dermal values by comparing the internal concentrations resulting from oral and dermal exposure scenarios. The PBTK model structure has been constructed to give a good simulation performance of biochemical processes within the human body. The model parameters are calibrated based on oral and dermal experimental data for the Caucasian population available in the literature. Particular attention is given to modelling the absorption stage (skin and gastrointestinal tract) in the form of several sub-compartments. This gives better model prediction results when compared to those of a PBTK model with a simpler structure of the absorption barrier. In addition, the role of quantitative structure-property relationships (QSPRs) in predicting skin penetration is evaluated for the three substances with a view to incorporating QSPR-predicted penetration parameters in the PBTK model when experimental values are lacking. Finally, PBTK modelling is used, first to extrapolate oral NOAEL doses derived from rat studies to humans, and then to simulate internal systemic/liver concentrations - Area Under Curve (AUC) and peak concentration - resulting from specified dermal and oral exposure conditions. Based on these simulations, AUC-based dermal thresholds for the three case study compounds are derived and compared with the experimentally obtained oral threshold (NOAEL) values. PMID:24731971

Gajewska, M; Worth, A; Urani, C; Briesen, H; Schramm, K-W

2014-06-16

286

Is the climate right for pleistocene rewilding? Using species distribution models to extrapolate climatic suitability for mammals across continents.  

Science.gov (United States)

Species distribution models (SDMs) are increasingly used for extrapolation, or predicting suitable regions for species under new geographic or temporal scenarios. However, SDM predictions may be prone to errors if species are not at equilibrium with climatic conditions in the current range and if training samples are not representative. Here the controversial "Pleistocene rewilding" proposal was used as a novel example to address some of the challenges of extrapolating modeled species-climate relationships outside of current ranges. Climatic suitability for three proposed proxy species (Asian elephant, African cheetah and African lion) was extrapolated to the American southwest and Great Plains using Maxent, a machine-learning species distribution model. Similar models were fit for Oryx gazella, a species native to Africa that has naturalized in North America, to test model predictions. To overcome biases introduced by contracted modern ranges and limited occurrence data, random pseudo-presence points generated from modern and historical ranges were used for model training. For all species except the oryx, models of climatic suitability fit to training data from historical ranges produced larger areas of predicted suitability in North America than models fit to training data from modern ranges. Four naturalized oryx populations in the American southwest were correctly predicted with a generous model threshold, but none of these locations were predicted with a more stringent threshold. In general, the northern Great Plains had low climatic suitability for all focal species and scenarios considered, while portions of the southern Great Plains and American southwest had low to intermediate suitability for some species in some scenarios. The results suggest that the use of historical, in addition to modern, range information and randomly sampled pseudo-presence points may improve model accuracy. This has implications for modeling range shifts of organisms in response to climate change. PMID:20877563

Richmond, Orien M W; McEntee, Jay P; Hijmans, Robert J; Brashares, Justin S

2010-01-01

287

Extrapolation of contrail investigations by LIDAR to larger scale measurements. Analysis and calibration of CCD camera and satellite images  

Energy Technology Data Exchange (ETDEWEB)

The CCD image of a persistent contrail and the coincident LIDAR measurement are presented. To extrapolate the LIDAR derived optical thickness to the video field of view an anisotropy correction and calibration has to be performed. Observed bright halo components result from highly regular oriented hexagonal crystals with sizes of 200 {mu}m-2 mm. This explained by measured ambient humidities below the formation threshold of natural cirrus. Optical thickness from LIDAR shows significant discrepancies to the result from coincident NOAA-14 data. Errors result from anisotropy correction and parameterized relations between AVHRR channels and optical properties. (author) 28 refs.

Sussmann, R.; Homburg, F.; Freudenthaler, V.; Jaeger, H. [Frauenhofer Inst. fuer Atmosphaerische Umweltforschung, Garmisch-Partenkirchen (Germany)

1997-12-31

288

Analytical solutions for diffuse fluorescence spectroscopy/imaging in biological tissues. Part I: zero and extrapolated boundary conditions.  

Science.gov (United States)

The mathematical model for diffuse fluorescence spectroscopy/imaging is represented by coupled partial differential equations (PDEs), which describe the excitation and emission light propagation in soft biological tissues. The generic closed-form solutions for these coupled PDEs are derived in this work for the case of regular geometries using the Green's function approach using both zero and extrapolated boundary conditions. The specific solutions along with the typical data types, such as integrated intensity and the mean time of flight, for various regular geometries were also derived for both time- and frequency-domain cases. PMID:23456130

Ayyalasomayajula, Kalyan Ram; Yalavarthy, Phaneendra K

2013-03-01

289

Continuum Limit of Lattice QCD with Staggered Quarks in the Quenched Approximation: A Critical Role for the Chiral Extrapolation  

International Nuclear Information System (INIS)

We calculate the light quark spectrum of lattice QCD in the quenched approximation using staggered quarks. We take the light quark mass, infinite volume, continuum limit. With nonlinear chiral extrapolations, we find that the nucleon to ? mass ratio is mN/m?=1.254±0.018± 0.028 , where the errors are statistical and systematic (within the quenched approximation), respectively. Since the experimental value is 1.22, our results indicate that the error due to quenching is approx-lt 5% . copyright 1998 The American Physical Society

290

Continuum limit of lattice QCD with staggered quarks in the quenched approximation a critical role for the chiral extrapolation  

CERN Document Server

We calculate the light quark spectrum of lattice QCD in the quenched approximation using Kogut-Susskind quarks. By combining results for different lattice spacings, several volumes and five quark masses, we are able to take the light quark mass, infinite volume, continuum limit. When we use non-linear chiral extrapolations, we find that the nucleon to rho mass ratio is 1.254 +- 0.018 +- 0.027, where the errors are statistical and systematic (within the quenched approximation), respectively. This should be compared with the experimental value of 1.22. Our results indicate that the error due to quenching is less than about 5%.

Bernard, C W; DeTar, C E; Gottlieb, S; Heller, U M; Hetrick, J E; McNeile, C; Rummukainen, K; Sugar, R; Toussaint, D; Bernard, Claude; Blum, Tom; Tar, Carleton De; Gottlieb, Steven; Heller, Urs M.; Hetrick, James E.; Neile, Craig Mc

1998-01-01

291

Extrapolation of the FOM 1MW free electron maser to a multi-megawatt millimeter microwave source  

Energy Technology Data Exchange (ETDEWEB)

A Free Electron Maser is now under test at the FOM Institute (Rijnhuizen) Netherlands with the goal of producing 1 MW long pulse to CW microwave output in the range 130 GHz to 250 GHz with wall plug efficiencies of 60%. An extrapolated version of this device is proposed, which would produce microwave power levels of up to 5 MW CW. This would allow for practical applications in such diverse areas as space power beaming, heating of fusion plasmas and hearing of high Mach number wind tunnels.

Caplan, M. [Lawrence Livermore National Lab., CA (United States); Valentini, M.; Verhoeven, A.; Urbanus, W. [FOM-Instituut voor Plasmafysica, Rijnhuizen (Netherlands); Tulupov, A. [Soliton-NTT Research Centre, Moscow (Russian Federation)

1996-12-01

292

Effect of heterogeneity of human population in cell radiosensitivity on the extrapolation of dose-response relationships to low doses  

International Nuclear Information System (INIS)

Presented are the results of an investigation of the dose-response relationship for the yield of chromosome aberrations in peripheral blood lymphocytes of persons with some hereditary diseases which represent the high risk group with respect to the increased incidence of malignant tumors and decreased life span. Despite substantially different absolute radiosensitivities of chromosomes, the variations of the alpha/beta ratio determining the extrapolation of experimental dose-response relationships to low doses did not prove to be too high, the mean deviation from the control being 15%. This points to the possible practical use of the dose-response relationships averaged over the human population as a whole

293

Estimated UV clutter levels at 10-100 meter sensor pixel resolution extrapolated from recent Polar Bear measurements  

International Nuclear Information System (INIS)

This paper describes the methodology and the results obtained at 1304 A wavelength from an analysis of the AFGL Polar Bear experiment. The basic measurement equipment provided data of a spatial resolution of 20 km over a large portion of the earth. The instrumentation also provided sampled outputs as the footprint scanned along the measurement track. The combination of the fine scanning and large area coverage provided opportunity for a spatial power spectral analysis that in turn provided a means for extrapolation to finer spatial scale

294

Ab initio post-HF CCSD(T Calculations for Triplet and Singlet Methylene in Four consecutive Dunning Basis Sets with Extrapolations to Infinite Limits for Various Molecular Properties  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract : Stationary points for four geometrically different states of methylene: bent and linear triplet methylene, bent and linear singlet methylene were investigated using the highly reliable post-HF CCSD(T method. Extrapolations to the CCSD(T basis set (CBS limit from Dunning triple to quintuple correlation consistent polarized basis sets were performed for total energies, for the equilibrium CH distances re(CH, for singlettriplet separation energies, for energy barriers to linearity and for correlation energies. Post-HF calculations with Dunning basis sets of the literature are presented for comparisons.

Günter Häfelinger

2005-01-01

295

Inflammatory findings on species extrapolations : humans are definitely no 70-kg mice  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Modern toxicology has embraced in vitro methods, and major hopes are based on the Omics technologies and systems biology approaches they bring along (Hartung and McBride in ALTEX 28(2):83–93, 2011; Hartung et al. in ALTEX 29(2):119–28, 2012). A culture of stringent validation has been developed for such approaches (Leist et al. in ALTEX 27(4):309–317, 2010; ALTEX 29(4):373–88, 2012a; Toxicol Res 1:8–22, 2012b), while the quality and usefulness of animal experiments have been little ...

Leist, Marcel; Hartung, Thomas

2013-01-01

296

The Fuzzy Logic Method for Simpler Forecasting  

Directory of Open Access Journals (Sweden)

Full Text Available Fildes and Makridakis (1998, Makridakis and Hibon (2000, and Fildes (2001 indicate that simple extrapolative forecasting methods that are robust forecast equally as well or better than more complicated methods, i.e. Box-Jenkins and other methods. We study the Direct Set Assignment (DSA extrapolative forecasting method. The DSA method is a non-linear extrapolative forecasting method developed within the Mamdani Development Framework, and designed to mimic the architecture of a fuzzy logic control system. We combine the DSA method Winters' Exponential smoothing. This combination provides the best observed forecast accuracy in seven of nine subcategories of time series, and is the top three in terms of observed accuracy in two subcategories. Hence, fuzzy logic which is the basis of the DSA method often is the best method for forecasting.

Jeffrey E. Jarrett

2011-08-01

297

Accurate potential energy surface for the 1(2)A' state of NH(2): scaling of external correlation versus extrapolation to the complete basis set limit.  

Science.gov (United States)

An accurate single-sheeted double many-body expansion potential energy surface is reported for the title system which is suitable for dynamics and kinetics studies of the reactions of N(2D) + H2(X1Sigmag+) NH(a1Delta) + H(2S) and their isotopomeric variants. It is obtained by fitting ab initio energies calculated at the multireference configuration interaction level with the aug-cc-pVQZ basis set, after slightly correcting semiempirically the dynamical correlation using the double many-body expansion-scaled external correlation method. The function so obtained is compared in detail with a potential energy surface of the same family obtained by extrapolating the calculated raw energies to the complete basis set limit. The topographical features of the novel global potential energy surface are examined in detail and found to be in general good agreement with those calculated directly from the raw ab initio energies, as well as previous calculations available in the literature. The novel function has been built so as to become degenerate at linear geometries with the ground-state potential energy surface of A'' symmetry reported by our group, where both form a Renner-Teller pair. PMID:20218704

Li, Y Q; Varandas, A J C

2010-09-16

298

Effects of partitioning and extrapolation on the connectivity of potential magnetic fields  

CERN Document Server

Coronal magnetic field may be characterized by how its field lines interconnect regions of opposing photospheric flux -- its connectivity. Connectivity can be quantified as the net flux connecting pairs of opposing regions, once such regions are identified. One existing algorithm will partition a typical active region into a number of unipolar regions ranging from a few dozen to a few hundred, depending on algorithmic parameters. This work explores how the properties of the partitions depend on some algorithmic parameters, and how connectivity depends on the coarseness of partitioning for one particular active region magnetogram. We find the number of connections among them scales with the number of regions even as the number of possible connections scales with its square. There are several methods of generating a coronal field, even a potential field. The field may be computed inside conducting boundaries or over an infinite half-space. For computation of connectivity, the unipolar regions may be replaced by...

Longcope, D W; Beveridge, C

2008-01-01

299

Extrapolation of urn models via poissonization: accurate measurements of the microbial unknown.  

Science.gov (United States)

The availability of high-throughput parallel methods for sequencing microbial communities is increasing our knowledge of the microbial world at an unprecedented rate. Though most attention has focused on determining lower-bounds on the ?-diversity i.e. the total number of different species present in the environment, tight bounds on this quantity may be highly uncertain because a small fraction of the environment could be composed of a vast number of different species. To better assess what remains unknown, we propose instead to predict the fraction of the environment that belongs to unsampled classes. Modeling samples as draws with replacement of colored balls from an urn with an unknown composition, and under the sole assumption that there are still undiscovered species, we show that conditionally unbiased predictors and exact prediction intervals (of constant length in logarithmic scale) are possible for the fraction of the environment that belongs to unsampled classes. Our predictions are based on a poissonization argument, which we have implemented in what we call the Embedding algorithm. In fixed i.e. non-randomized sample sizes, the algorithm leads to very accurate predictions on a sub-sample of the original sample. We quantify the effect of fixed sample sizes on our prediction intervals and test our methods and others found in the literature against simulated environments, which we devise taking into account datasets from a human-gut and -hand microbiota. Our methodology applies to any dataset that can be conceptualized as a sample with replacement from an urn. In particular, it could be applied, for example, to quantify the proportion of all the unseen solutions to a binding site problem in a random RNA pool, or to reassess the surveillance of a certain terrorist group, predicting the conditional probability that it deploys a new tactic in a next attack. PMID:21738613

Lladser, Manuel E; Gouet, Raúl; Reeder, Jens

2011-01-01

300

Quantitative Cross-Species Extrapolation between Humans and Fish: The Case of the Anti-Depressant Fluoxetine.  

Science.gov (United States)

Fish are an important model for the pharmacological and toxicological characterization of human pharmaceuticals in drug discovery, drug safety assessment and environmental toxicology. However, do fish respond to pharmaceuticals as humans do? To address this question, we provide a novel quantitative cross-species extrapolation approach (qCSE) based on the hypothesis that similar plasma concentrations of pharmaceuticals cause comparable target-mediated effects in both humans and fish at similar level of biological organization (Read-Across Hypothesis). To validate this hypothesis, the behavioural effects of the anti-depressant drug fluoxetine on the fish model fathead minnow (Pimephales promelas) were used as test case. Fish were exposed for 28 days to a range of measured water concentrations of fluoxetine (0.1, 1.0, 8.0, 16, 32, 64 µg/L) to produce plasma concentrations below, equal and above the range of Human Therapeutic Plasma Concentrations (HTPCs). Fluoxetine and its metabolite, norfluoxetine, were quantified in the plasma of individual fish and linked to behavioural anxiety-related endpoints. The minimum drug plasma concentrations that elicited anxiolytic responses in fish were above the upper value of the HTPC range, whereas no effects were observed at plasma concentrations below the HTPCs. In vivo metabolism of fluoxetine in humans and fish was similar, and displayed bi-phasic concentration-dependent kinetics driven by the auto-inhibitory dynamics and saturation of the enzymes that convert fluoxetine into norfluoxetine. The sensitivity of fish to fluoxetine was not so dissimilar from that of patients affected by general anxiety disorders. These results represent the first direct evidence of measured internal dose response effect of a pharmaceutical in fish, hence validating the Read-Across hypothesis applied to fluoxetine. Overall, this study demonstrates that the qCSE approach, anchored to internal drug concentrations, is a powerful tool to guide the assessment of the sensitivity of fish to pharmaceuticals, and strengthens the translational power of the cross-species extrapolation. PMID:25338069

Margiotta-Casaluci, Luigi; Owen, Stewart F; Cumming, Rob I; de Polo, Anna; Winter, Matthew J; Panter, Grace H; Rand-Weaver, Mariann; Sumpter, John P

2014-01-01

 
 
 
 
301

Quantitative Cross-Species Extrapolation between Humans and Fish: The Case of the Anti-Depressant Fluoxetine  

Science.gov (United States)

Fish are an important model for the pharmacological and toxicological characterization of human pharmaceuticals in drug discovery, drug safety assessment and environmental toxicology. However, do fish respond to pharmaceuticals as humans do? To address this question, we provide a novel quantitative cross-species extrapolation approach (qCSE) based on the hypothesis that similar plasma concentrations of pharmaceuticals cause comparable target-mediated effects in both humans and fish at similar level of biological organization (Read-Across Hypothesis). To validate this hypothesis, the behavioural effects of the anti-depressant drug fluoxetine on the fish model fathead minnow (Pimephales promelas) were used as test case. Fish were exposed for 28 days to a range of measured water concentrations of fluoxetine (0.1, 1.0, 8.0, 16, 32, 64 µg/L) to produce plasma concentrations below, equal and above the range of Human Therapeutic Plasma Concentrations (HTPCs). Fluoxetine and its metabolite, norfluoxetine, were quantified in the plasma of individual fish and linked to behavioural anxiety-related endpoints. The minimum drug plasma concentrations that elicited anxiolytic responses in fish were above the upper value of the HTPC range, whereas no effects were observed at plasma concentrations below the HTPCs. In vivo metabolism of fluoxetine in humans and fish was similar, and displayed bi-phasic concentration-dependent kinetics driven by the auto-inhibitory dynamics and saturation of the enzymes that convert fluoxetine into norfluoxetine. The sensitivity of fish to fluoxetine was not so dissimilar from that of patients affected by general anxiety disorders. These results represent the first direct evidence of measured internal dose response effect of a pharmaceutical in fish, hence validating the Read-Across hypothesis applied to fluoxetine. Overall, this study demonstrates that the qCSE approach, anchored to internal drug concentrations, is a powerful tool to guide the assessment of the sensitivity of fish to pharmaceuticals, and strengthens the translational power of the cross-species extrapolation. PMID:25338069

Margiotta-Casaluci, Luigi; Owen, Stewart F.; Cumming, Rob I.; de Polo, Anna; Winter, Matthew J.; Panter, Grace H.; Rand-Weaver, Mariann; Sumpter, John P.

2014-01-01

302

Extrapolating population size from the occupancy-abundance relationship and the scaling pattern of occupancy  

DEFF Research Database (Denmark)

The estimation of species abundances at regional scales requires a cost-efficient method that can be applied to existing broadscale data. We compared the performance of eight models for estimating species abundance and community structure from presence-absence maps of the southern African avifauna. Six models were based on the intraspecific occupancy-abundance relationship (OAR); the other two on the scaling pattern of species occupancy (SPO), which quantifies the decline in species range size when measured across progressively finer scales. The performance of these models was examined using five tests: the first three compared the predicted community structure against well-documented macroecological patterns; the final two compared published abundance estimates for rare species and the total regional abundance estimate against predicted abundances. Approximately two billion birds were estimated as occurring in South Africa, Lesotho, and Swaziland. SPO models outperformed the OAR models, due to OAR models assuming environmental homogeneity and yielding scale-dependent estimates. Therefore, OAR models should only be applied across small, homogenous areas. By contrast, SPO models are suitable for data at larger spatial scales because they are based on the scale dependence of species range size and incorporate environmental heterogeneity (assuming fractal habitat structure or performing a Bayesian estimate of occupancy). Therefore, SPO models are recommended for assemblage-scale regional abundance estimation based on spatially explicit presence-absence data.

Hui, Cang; McGeoch, Melodie A.

2009-01-01

303

A totally deflated lung's CT image construction by means of extrapolated deformable registration  

Science.gov (United States)

A novel technique is proposed to construct CT image of a totally deflated lung using breath-hold lung's preoperative CT images acquired during respiration. Such a constructed CT image is very useful in tumor targeting during tumor ablative procedures such as lung brachytherapy used for lung cancer treatment. To minimize motion within the target lung, tumor ablative procedures are frequently performed while the lung is totally deflated. Deflating the lung during such procedures renders pre-operative images ineffective for tumor targeting, because those images correspond to the lung while it is partially inflated. Furthermore, the problem cannot be solved using intra-operative Ultrasound (US) images. This is because the quality of lung US images degrades substantially as a result of the residual air inside the deflated lung, thus it is not an effective intra-operative imaging modality by itself. One possible approach for image-guided lung brachytherapy is to register high quality preoperative CT images of the deflated lung with their corresponding low quality intra-operative US images. To obtain the CT images of deflated lung, a novel image construction technique is presented. The proposed technique was implemented using two deformable registration methods: multi-resolution B-spline and multi-resolution demons. The technique was applied to ex vivo porcine lungs where results obtained were found to be very encouraging.

Sadeghi Naini, Ali; Patel, Rajni V.; Samani, Abbas

2011-03-01

304

Antioxidant potential of selected supplements in vitro and the problem of its extrapolation for in vivo  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: antioxidants, free radicals and oxidative stress have been studied extensively for quite some time but their role in diseases and their prevention has not been clearly determined. Because commercialantioxidants do not need to pass clinical tests in order to be sold over the counter we have decided to test the antioxidant potential of different commercial preparations with the antioxidative properties.Methods: pH, rH and oxidant-reduction potential of different preparations in aqueous solution was measured. Afterwards antioxidant potential using FormPlus® after adding the preparation to human blood as a morecomplex environment with different homeostasis mechanisms was determined.Results: all the results showed expected change compared to the control but the results in aqueous solution did not match the results obtained from the human blood, as was expected.Conclusion: from the experiments it can be concluded that while the preparations did show antioxidant activity, it is very difficult and even wrong to predict the antioxidant potential of an antioxidant preparationadded to human blood, let alone in a living organism, based just on the results obtained in aqueous solution. Further possibilities for research include more extensive studies of antioxidant preparations in more complex environment and last but not least in test organisms or in human trials.

Julija Ogrin Papi?

2012-04-01

305

Inflammatory findings on species extrapolations: humans are definitely no 70-kg mice.  

Science.gov (United States)

Modern toxicology has embraced in vitro methods, and major hopes are based on the Omics technologies and systems biology approaches they bring along (Hartung and McBride in ALTEX 28(2):83-93, 2011; Hartung et al. in ALTEX 29(2):119-28, 2012). A culture of stringent validation has been developed for such approaches (Leist et al. in ALTEX 27(4):309-317, 2010; ALTEX 29(4):373-88, 2012a; Toxicol Res 1:8-22, 2012b), while the quality and usefulness of animal experiments have been little scrutinized. A new study (Seok et al. 2013) now shows the low predictivity of animal responses in the field of inflammation. These findings corroborate earlier findings from comparisons in the fields of neurodegeneration, stroke and sepsis. The low predictivity of animal experiments in research areas allowing direct comparisons of mouse versus human data puts strong doubt on the usefulness of animal data as key technology to predict human safety. PMID:23503654

Leist, Marcel; Hartung, Thomas

2013-04-01

306

Phase shift analysis of ?? system at energies between 500 and 1370 MeV with Chew-Low extrapolation results from reactions ?-p?p?-?0 and ?-p?n?+?- at 3.92 GeV/c  

International Nuclear Information System (INIS)

Experimental data (12 evts/?N???N reactions) were derived from the analysis of 450000 pictures obtained with the 2 meter hydrogen bubble chamber at CERN. The Chew-Low extrapolation method was used to obtain total and differential cross-sections of ?+0?-??+0?- reactions. Pseudo-peripherism hypothesis, in agreement with data at energy less 1 GeV, was modified to take into account the non-vanishing reactions amplitude at t=0, observed above 1 GeV. Several phase shift analyses were done, either with energy parametrisation of phase shifts, or at fixed energy. Main results concern the parameters of S* (Jsup(P)=0+) resonance which come out from a meromorphic parametrisation of the S0 wave amplitude in the region of the KantiK channel threshold (987 MeV) and the dynamical wave structures in the f0 (Jsup(P)=2+) resonance region. The agreement observed between these results and those of main previous experiments is a proof of the usefulness of the extrapolation method above 1 GeV

307

Extrapolation of Normal Tissue Complication Probability for Different Fractionations in Liver Irradiation  

International Nuclear Information System (INIS)

Purpose: The ability to predict normal tissue complication probability (NTCP) is essential for NTCP-based treatment planning. The purpose of this work is to estimate the Lyman NTCP model parameters for liver irradiation from published clinical data of different fractionation regimens. A new expression of normalized total dose (NTD) is proposed to convert NTCP data between different treatment schemes. Method and Materials: The NTCP data of radiation- induced liver disease (RILD) from external beam radiation therapy for primary liver cancer patients were selected for analysis. The data were collected from 4 institutions for tumor sizes in the range of of 8-10 cm. The dose per fraction ranged from 1.5 Gy to 6 Gy. A modified linear-quadratic model with two components corresponding to radiosensitive and radioresistant cells in the normal liver tissue was proposed to understand the new NTD formalism. Results: There are five parameters in the model: TD50, m, n, ?/? and f. With two parameters n and ?/? fixed to be 1.0 and 2.0 Gy, respectively, the extracted parameters from the fitting are TD50(1) = 40.3 ± 8.4Gy, m =0.36 ± 0.09, f = 0.156 ± 0.074 Gy and TD50(1) = 23.9 ± 5.3Gy, m = 0.41 ± 0.15, f = 0.0 ± 0.04 Gy for patients with liver cirrhosis scores of Child-Pugh A and Child-Pugh B, respectively. The fitting results showed that the liver cirrhosis score significantly affects fractional dose dependence of NTD. Conclusion: The Lyman parameters generated presently and the new form of NTD may be used to predict NTCP for treatment planning of innovative liver irradiation with different fractionations, such as hypofractioned stereotactic body radiation therapy.

308

Searching for Inflationary B-modes: Can dust emission properties be extrapolated from 350 GHz to 150 GHz?  

CERN Document Server

Recent Planck results have shown that the path to isolating an inflationary B-mode signal in microwave polarization passes through understanding and modeling the interstellar dust polarized emission foreground, even in regions of the sky with the lowest level of dust emission. One of the most commonly used ways to remove the dust foreground is to extrapolate the polarized dust emission signal from frequencies where it dominates (e.g., 350 GHz) to frequencies commonly targeted by cosmic microwave background experiments (e.g., 150 GHz). We show, using a simple 2-cloud model, that if more than one cloud is present along the line-of-sight, with even mildly different temperature and dust column density, but severely misaligned magnetic field, then the 350 GHz polarized sky map is not predictive of that at 150 GHz. This problem is intrinsic to all microwave experiments and is due to information loss due to line-of-sight integration. However, it can be alleviated through interstellar medium tomography: a reconstruct...

Tassis, Konstantinos

2014-01-01

309

Instability of D-dimensional extremally charged Reissner-Nordstrom(-de Sitter) black holes: extrapolation to arbitrary D  

CERN Document Server

In our earlier work (PRL 103 (2009) 161101) it was shown that nonextremal highly charged Reissner-Nordstrom-de Sitter black holes are gravitationally unstable in D>6-dimensional space-times. Here, we find accurate threshold values of the $\\Lambda$-term at which the instability of the extremally charged black holes starts. The larger D, the smaller is the threshold $\\Lambda$. Extrapolation of the data for D=7, 8,... 11 shows that the threshold instability value of the ratio $\\rho = r_{h}/r_{cos}$ (where $r_{cos}$ and $r_{h}$ are the cosmological and event horizons) approaches zero as $\\sim e^{-(D-4)/2}$, when D goes to infinity. This is numerical evidence that extremally charged Reissner-Nodtrom-de Sitter black holes are gravitationally unstable for all D>6, while asymptotically flat extremally charged Reissner-Nordstrom black holes are stable for all D. The instability is not connected to the horizon instability discussed recently in the literature, and, unlike the later one, develops also outside the event h...

Konoplya, R A

2014-01-01

310

What you see may not always be what you get : Bioavailability and extrapolation from in vitro tests  

DEFF Research Database (Denmark)

In human risk assessment, bioavailability needs to be considered when relying on in vitro toxicity results. For single chemicals, this quantitative challenge is often handled through a bioavailability factor. For mixtures, however, things are more complicated. Thus, individual constituents may not only interact toxicodynamically and toxicokinetically, but the composition of constituents reaching the target site may also differ from what was present at the site of exposure due to the differences in their bioavailabilities. A recent study concluded on the in vivo potential of Australian tea-tree oil (TTO) to act as an endocrine disruptor based on an in vitro protocol measuring the growth of MCF-7 cells following chemical exposure to TTO. TTO is primarily used topically in humans, and is not a single chemical but is a mixture with some constituents penetrating the skin which others do not. The present study evaluated in an identical in vitro model to what extent TTO and its skin penetrating constituents affected the growth of MCF-7 cells. The estrogenic potency of TTO was confirmed, but none of the bioavailable TTO constituents demonstrated estrogenicity. The present study, therefore, cautions in vitro to in vivo extrapolations from the mixtures of constituents with potentially varying bioavailabilities. Udgivelsesdato: June

Nielsen, Jesper Bo

2008-01-01

311

Using the fish plasma model for comparative hazard identification for pharmaceuticals in the environment by extrapolation from human therapeutic data.  

Science.gov (United States)

Thousands of drugs are currently in use, but only for a few of them experimental chronic fish data exist. Therefore, Huggett et al. (Human Ecol Risk Assess 2003; 9:1789-1799) proposed the fish plasma model (FPM) to extrapolate the potential of unintended long-term effects in fish. The FPM compares human therapeutic plasma concentrations (HPC(T)) with estimated fish steady-state concentrations (FPC(ss)), under the assumption that biological drug targets may be conserved across the species. In this study, the influence of using different input parameters on the model result was characterised for 42 drugs. The existence of structurally and functionally conserved protein targets in zebrafish could not be refuted. Thus, the FPM model application was not in contradiction to its basic assumption. Further, dissociation of drugs was shown to be important in determining the output and model robustness. As the proposed model for FPC(ss) estimation was considered to predict accurate values for neutral and lipophilic chemicals only, a modified bioconcentration model was used with D(OW) as predictor. Using reasonable worst case assumptions, a hazard was indicated for one third of the selected drugs. Our results support the notion that this approach might help to prioritise among in use drugs to identify compounds where follow up evidence should be considered. PMID:21889559

Schreiber, René; Gündel, Ulrike; Franz, Stephanie; Küster, Anette; Rechenberg, Bettina; Altenburger, Rolf

2011-12-01

312

The 16O(p,?)17F direct capture cross section with an extrapolation to astrophysical energies  

International Nuclear Information System (INIS)

The cross section for the direct radiative capture of protons by 16O has been measured relative to the proton elastic scattering cross section for energies from 800 to 2400 keV (CM). The elastic scattering cross section was normalized to the Rutherford scattering cross section at 385.5 keV. The capture cross section for the reaction 16O(p,?)17F, which plays a role in hydrogen burning stars, has been extrapolated to stellar energies using a theoretical model which gives a good fit to the measured cross sections. The model involves calculation of electromagnetic matrix elements between initial and final state wave functions evaluated for Saxon-Woods potentials with parameters adjusted to fit both elastic scattering data and binding energies for the ground and first excited states of 17F. Cross sections for capture to the 5/2+ ground and 1/2+ first excited states of 17F in terms of astrophysical S factors valid for energies less than or equal to 100 keV have been found. (author)

313

Extrapolation of the dna fragment-size distribution after high-dose irradiation to predict effects at low doses  

Science.gov (United States)

The patterns of DSBs induced in the genome are different for sparsely and densely ionizing radiations: In the former case, the patterns are well described by a random-breakage model; in the latter, a more sophisticated tool is needed. We used a Monte Carlo algorithm with a random-walk geometry of chromatin, and a track structure defined by the radial distribution of energy deposition from an incident ion, to fit the PFGE data for fragment-size distribution after high-dose irradiation. These fits determined the unknown parameters of the model, enabling the extrapolation of data for high-dose irradiation to the low doses that are relevant for NASA space radiation research. The randomly-located-clusters formalism was used to speed the simulations. It was shown that only one adjustable parameter, Q, the track efficiency parameter, was necessary to predict DNA fragment sizes for wide ranges of doses. This parameter was determined for a variety of radiations and LETs and was used to predict the DSB patterns at the HPRT locus of the human X chromosome after low-dose irradiation. It was found that high-LET radiation would be more likely than low-LET radiation to induce additional DSBs within the HPRT gene if this gene already contained one DSB.

Ponomarev, A. L.; Cucinotta, F. A.; Sachs, R. K.; Brenner, D. J.; Peterson, L. E.

2001-01-01

314

A study of the inhibition of iron corrosion in HCl solutions by some amino acids  

International Nuclear Information System (INIS)

The performance of three selected amino acids, namely alanine (Ala), cysteine (Cys) and S-methyl cysteine (S-MCys) as safe corrosion inhibitors for iron in aerated stagnant 1.0 M HCl solutions was evaluated by Tafel polarization and impedance measurements. Results indicate that Ala acts mainly as a cathodic inhibitor, while Cys and S-MCys function as mixed-type inhibitors. Cys, which contains a mercapto group in its molecular structure, was the most effective among the inhibitors tested, while Ala was less effective than S-MCys. The low inhibition efficiency recorded for S-MCys compared with that of Cys was attributed to steric effects caused by the substituent methyl on the mercapto group. Electrochemical frequency modulation (EFM) technique and inductively coupled plasma atomic emission spectrometry (ICP-AES), were also applied to make accurate determination of corrosion rates. Validation of the Tafel extrapolation method for measuring corrosion rates was tested. Rates of corrosion rates (in ?m y-1) obtained from Tafel extrapolation method are in good agreement with those measured using EFM and ICP methods. Some theoretical studies, including molecular dynamics (MD) and density functional theory (DFT), were also employed to establish the correlation between the structure (molecular and electronic) of the three tested inhibitors and the inhibition efficiency. Adsorption via hydrogen bonding was discussed here based on some theoretical studies. Experimental and theoretical results were in good agreement.

315

A study of the inhibition of iron corrosion in HCl solutions by some amino acids  

Energy Technology Data Exchange (ETDEWEB)

The performance of three selected amino acids, namely alanine (Ala), cysteine (Cys) and S-methyl cysteine (S-MCys) as safe corrosion inhibitors for iron in aerated stagnant 1.0 M HCl solutions was evaluated by Tafel polarization and impedance measurements. Results indicate that Ala acts mainly as a cathodic inhibitor, while Cys and S-MCys function as mixed-type inhibitors. Cys, which contains a mercapto group in its molecular structure, was the most effective among the inhibitors tested, while Ala was less effective than S-MCys. The low inhibition efficiency recorded for S-MCys compared with that of Cys was attributed to steric effects caused by the substituent methyl on the mercapto group. Electrochemical frequency modulation (EFM) technique and inductively coupled plasma atomic emission spectrometry (ICP-AES), were also applied to make accurate determination of corrosion rates. Validation of the Tafel extrapolation method for measuring corrosion rates was tested. Rates of corrosion rates (in {mu}m y{sup -1}) obtained from Tafel extrapolation method are in good agreement with those measured using EFM and ICP methods. Some theoretical studies, including molecular dynamics (MD) and density functional theory (DFT), were also employed to establish the correlation between the structure (molecular and electronic) of the three tested inhibitors and the inhibition efficiency. Adsorption via hydrogen bonding was discussed here based on some theoretical studies. Experimental and theoretical results were in good agreement.

Amin, Mohammed A. [Chemistry Department, Faculty of Science, Ain Shams University, Abbassia, 11566 Cairo (Egypt); Materials and Corrosion Lab (MCL), Chemistry Department, Faculty of Science, Taif University, 888 Hawaiya (Saudi Arabia)], E-mail: maaismail@yahoo.com; Khaled, K.F. [Materials and Corrosion Lab (MCL), Chemistry Department, Faculty of Science, Taif University, 888 Hawaiya (Saudi Arabia); Electrochemistry Research Laboratory, Chemistry Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Mohsen, Q. [Materials and Corrosion Lab (MCL), Chemistry Department, Faculty of Science, Taif University, 888 Hawaiya (Saudi Arabia); Arida, H.A. [Materials and Corrosion Lab (MCL), Chemistry Department, Faculty of Science, Taif University, 888 Hawaiya (Saudi Arabia); Hot Laboratories Center, Atomic Energy Authority, 13759 Cairo (Egypt)

2010-05-15

316

Hot tensile and creep rupture data extrapolation on 2.25Cr-1Mo steel using the CDM Penny-Kachanov methodology  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Hot tensile and creep data were obtained for 2.25Cr-1Mo steel, ASTM A387 Gr.22CL2, at the temperatures of 500-550-600-650-700 °C. Using the concept of equivalence between hot tensile data and creep data, the results were analyzed according to the methodology based on Kachanov Continuum Damage Mechan [...] ics proposed by Penny, which suggests the possibility of using short time creep data obtained in laboratory for extrapolation to long operating times corresponding to tens of thousands hours. The hot tensile data (converted to creep) define in a better way the region where ?=0 and the creep data define the region where ?=1, according to the methodology. Extrapolation to 10,000 h and 100,000 h is performed and the results compared with results obtained by other extrapolation procedures such as the Larson-Miller and Manson-Haferd methodologies. Extrapolation from ASTM and NIMS Datasheets for 10,000 h and 100,000 h as well as data from other authors on 2.25Cr-1Mo steel are used for assessing the reliability of the results.

José Francisco dos, Reis Sobrinho; Levi de Oliveira, Bueno.

2014-04-01

317

CDNA CLONING OF FATHEAD MINNOW (PIMEPHALES PROMELAS) ESTROGEN AND ANDROGEN RECEPTORS FOR USE IN STEROID RECEPTOR EXTRAPOLATION STUDIES FOR ENDOCRINE DISRUPTING CHEMICALS  

Science.gov (United States)

cDNA Cloning of Fathead minnow (Pimephales promelas) Estrogen and Androgen Receptors for Use in Steroid Receptor Extrapolation Studies for Endocrine Disrupting Chemicals. Wilson, V.S.1,, Korte, J.2, Hartig P. 1, Ankley, G.T.2, Gray, L.E., Jr 1, , and Welch, J.E.1. 1U.S...

318

Hot tensile and creep rupture data extrapolation on 2.25Cr-1Mo steel using the CDM Penny-Kachanov methodology  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Hot tensile and creep data were obtained for 2.25Cr-1Mo steel, ASTM A387 Gr.22CL2, at the temperatures of 500-550-600-650-700 °C. Using the concept of equivalence between hot tensile data and creep data, the results were analyzed according to the methodology based on Kachanov Continuum Damage Mechan [...] ics proposed by Penny, which suggests the possibility of using short time creep data obtained in laboratory for extrapolation to long operating times corresponding to tens of thousands hours. The hot tensile data (converted to creep) define in a better way the region where ?=0 and the creep data define the region where ?=1, according to the methodology. Extrapolation to 10,000 h and 100,000 h is performed and the results compared with results obtained by other extrapolation procedures such as the Larson-Miller and Manson-Haferd methodologies. Extrapolation from ASTM and NIMS Datasheets for 10,000 h and 100,000 h as well as data from other authors on 2.25Cr-1Mo steel are used for assessing the reliability of the results.

José Francisco dos, Reis Sobrinho; Levi de Oliveira, Bueno.

319

Is the beagle dog an appropriate experimental animal for extrapolating data to humans on organ distribution patterns of U, Th, and Pu  

International Nuclear Information System (INIS)

dy content. This difference may have been due to differences in the mode of intake of Pu in each species or to differences in the chemical form of Pu. In general, the results suggest that the beagle may be an appropriate experimental animal from which to extrapolate data to humans with reference to the percentage of U, Th, and Pu found in the organs

320

Extrapolation of creep behavior of high-density polyethylene liner in the Catch Basin of grout vaults  

International Nuclear Information System (INIS)

Testing was performed to determine if gravel particles will creep into and puncture the high-density polyethylene (HDPE) liner in the catch basin of a grout vault over a nominal 30-year period. Testing was performed to support a design without a protective geotextile cover after the geotextile was removed from the design. Recently, a protective geotextile cover over the liner was put back into the design. The data indicate that the geotextile has an insignificant effect on the creep of gravel into the liner. However, the geotextile may help to protect the liner during construction. Two types of tests were performed to evaluate the potential for creep-related puncture. In the first type of test, a very sensitive instrument measured the rate at which a probe crept into HDPE over a 20-minute period at temperatures of 176 degrees F to 212 degrees F (80 degrees C to 100 degrees C). The second type of test consisted of placing the liner between gravel and mortar at 194 degrees F (90 degrees C) and 45.1 psi overburden pressure for periods up to 1 year. By combining data from the two tests, the long-term behavior of the creep was extrapolated to 30 years of service. After 30 years of service, the liner will be in a nearly steady condition and further creep will be extremely small. The results indicate that the creep of gravel into the liner will not create a puncture during service at 194 degrees F (90 degrees C). The estimated creep over 30 years is expected to be less than 25 mils out of the total initial thickness of 60 mils. The test temperature of 194 degrees F (90 degrees C) corresponds to the design basis temperature of the vault. Lower temperatures are expected at the liner, which makes the test conservative. Only the potential for failure of the liner resulting from creep of gravel is addressed in this report

 
 
 
 
321

Cross-species extrapolation of prediction model for lead transfer from soil to corn grain under stress of exogenous lead.  

Science.gov (United States)

There has been increasing concern in recent years regarding lead (Pb) transfer in the soil-plant system. In this study the transfer of Pb (exogenous salts) was investigated from a wide range of Chinese soils to corn grain (Zhengdan 958). Prediction models were developed with combination of the Pb bioconcentration factor (BCF) of Zhengdan 958, and soil pH, organic matter (OM) content, and cation exchange capacity (CEC) through multiple stepwise regressions. Moreover, these prediction models from Zhengdan 958 were applied to other non-model corn species through cross-species extrapolation approach. The results showed that the soil pH and OM were the major factors that controlled Pb transfer from soil to corn grain. The lower pH and OM could improve the bioaccumulation of Pb in corn grain. No significant differences were found between two prediction models derived from the different exogenous Pb contents. When the prediction models were applied to other non-model corn species, the ratio ranges between the predicted BCF values and the measured BCF values were within an interval of 2-fold and close to the solid line of 1?1 relationship. Moreover, the prediction model i.e. Log[BCF]?=?-0.098 pH-0.150 log[OM] -1.894 at the treatment of high Pb can effectively reduce the measured BCF intra-species variability for all non-model corn species. These suggested that this prediction model derived from the high Pb content was more adaptable to be applied to other non-model corn species to predict the Pb bioconcentration in corn grain and assess the ecological risk of Pb in different agricultural soils. PMID:24416440

Li, Zhaojun; Yang, Hua; Li, Yupeng; Long, Jian; Liang, Yongchao

2014-01-01

322

Extrapolation-to-Flight of Aerodynamic Heating Measurements and Determination of In-Flight Radiation-Equilibrium Surface Temperature in Hypersonic / High Enthalpy Flow Conditions  

Science.gov (United States)

The previously demonstrated success of the reference enthalpy concept in heat transfer prediction at hypersonic flow conditions is utilized herein to propose a cost- effective methodology for extrapolation- o-flight of Stanton number measurements (or baseline computational results), and the determination of radiation-equilibrium surface temperatures that develop on actual vehicle surfaces during hypersonic / high enthalpy flight conditions. The methodology couples the (analytical) generalized reference enthalpy solution with Euler computations (providing input data along the edge of thin boundary layers) and is, therefore, significantly cheaper and more efficient than the execution of full Navier- Stokes computations that are presently incorporated, particularly so in the thermo-chemically active high enthalpy flow regime. The validity of the proposed methodology is demonstrated in a first step by means of two- dimensional test cases, whereby extrapolated data accuracy is better than 20%.

Simeonides, G. A.

2009-01-01

323

Assessment of the hepatic veins in poor contrast conditions using dual energy CT. Evaluation of a novel monoenergetic extrapolation software algorithm  

Energy Technology Data Exchange (ETDEWEB)

Purpose: To evaluate a novel monoenergetic post-processing algorithm (MEI+) in patients with poor intrahepatic contrast enhancement. Materials and Methods: 25 patients were retrospectively included in this study. Late-phase imaging of the upper abdomen, which was acquired in dual-energy mode (100/140 kV), was used as a model for poor intrahepatic contrast enhancement. Traditional monoenergetic images (MEI), linearly weighted mixed images with different mixing ratios (MI), sole 100 and 140 kV and MEI+ images were calculated. MEI+ is a novel technique which applies frequency-based mixing of the low keV images and an image of optimal keV from a noise perspective to combine the benefits of both image stacks. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the intrahepatic vasculature (IHV) and liver parenchyma (LP) were objectively measured and depiction of IHV was subjectively rated and correlated with portal venous imaging by two readers in consensus. Results: MEI+ was able to increase the SNR of the IHV (5.7 ± 0.4 at 40 keV) and LP (4.9 ± 1.0 at 90 keV) and CNR (2.1 ± 0.6 at 40 keV) greatly compared to MEI (5.1 ± 1.1 at 80 keV, 4.7 ± 1.0 at 80 keV, 1.0 ± 0.4 at 70 keV), MI (5.2 ± 1.1 M5:5, 4.8 ± 1.0 M5:5, 1.0 ± 3.5 M9:1), sole 100 kV images (4.4 ± 1.0, 3.7 ± 0.8, 1.0 ± 0.3) and 140 kV images (2.8 ± 0.5, 3.1 ± 0.6, 0.1 ± 0.2). Subjective assessment rated MEI+ of virtual 40 keV superior to all other images. Conclusion: MEI+ is a very promising algorithm for monoenergetic extrapolation which is able to overcome noise limitations associated with traditional monoenergetic techniques at low virtual keV levels and consequently does not suffer from a decline of SNR and CNR at low keV values. This algorithm allows an improvement of IHV depiction in the presence of poor contrast. (orig.)

Schabel, C.; Bongers, M.; Grosse, U.; Mangold, S.; Claussen, C.D.; Thomas, C. [University Hospital of Tuebingen (Germany). Dept. of Diagnostic and Interventional Radiology; Sedlmair, M. [Siemens AG, Forchheim (Germany). Healthcare; Korn, A. [University Hospital of Tuebingen (Germany). Dept. of Diagnostic and Interventional Neuroradiology

2014-06-15

324

Assessment of the hepatic veins in poor contrast conditions using dual energy CT. Evaluation of a novel monoenergetic extrapolation software algorithm  

International Nuclear Information System (INIS)

Purpose: To evaluate a novel monoenergetic post-processing algorithm (MEI+) in patients with poor intrahepatic contrast enhancement. Materials and Methods: 25 patients were retrospectively included in this study. Late-phase imaging of the upper abdomen, which was acquired in dual-energy mode (100/140 kV), was used as a model for poor intrahepatic contrast enhancement. Traditional monoenergetic images (MEI), linearly weighted mixed images with different mixing ratios (MI), sole 100 and 140 kV and MEI+ images were calculated. MEI+ is a novel technique which applies frequency-based mixing of the low keV images and an image of optimal keV from a noise perspective to combine the benefits of both image stacks. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the intrahepatic vasculature (IHV) and liver parenchyma (LP) were objectively measured and depiction of IHV was subjectively rated and correlated with portal venous imaging by two readers in consensus. Results: MEI+ was able to increase the SNR of the IHV (5.7 ± 0.4 at 40 keV) and LP (4.9 ± 1.0 at 90 keV) and CNR (2.1 ± 0.6 at 40 keV) greatly compared to MEI (5.1 ± 1.1 at 80 keV, 4.7 ± 1.0 at 80 keV, 1.0 ± 0.4 at 70 keV), MI (5.2 ± 1.1 M5:5, 4.8 ± 1.0 M5:5, 1.0 ± 3.5 M9:1), sole 100 kV images (4.4 ± 1.0, 3.7 ± 0.8, 1.0 ± 0.3) and 140 kV images (2.8 ± 0.5, 3.1 ± 0.6, 0.1 ± 0.2). Subjective assessment rated MEI+ of virtual 40 keV superior to all other images. Conclusion: MEI+ is a very promising algorithm for monoenergetic extrapolation which is able to overcome noise limitations associated with traditional monoenergetic techniques at low virtual keV levels and consequently does not suffer from a decline of SNR and CNR at low keV values. This algorithm allows an improvement of IHV depiction in the presence of poor contrast. (orig.)

325

Nonlinear force-free field extrapolation in spherical geometry: improved boundary data treatment applied to a SOLIS/VSM vector magnetogram  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Routine measurements of the solar magnetic field are mainly carried out in the photosphere. Therefore, one has to infer the field strength in the higher layers of the solar atmosphere from the measured photospheric field based on the assumption that the corona is force-free. Meanwhile, those measured data are inconsistent with the above force-free assumption. Therefore, one has to apply some transformations to these data before nonlinear force-free extrapolation codes can be...

Tadesse, Tilaye; Wiegelmann, T.; Inhester, B.; Pevtsov, A.

2010-01-01

326

Nonlinear Force-Free Field Extrapolation of a Coronal Magnetic Flux Rope Supporting a Large-Scale Filament from Photospheric Vector Magnetogram  

CERN Document Server

Solar filament are commonly thought to be supported in magnetic dips, in particular, of magnetic flux ropes (FRs). In this Letter, from the observed photospheric vector magnetogram, we implement a nonlinear force-free field (NLFFF) extrapolation of a coronal magnetic FR that supports a large-scale intermediate filament between an active region and a weak polarity region. This result is the first in that current NLFFF extrapolations with presence of FRs are limited to relatively small-scale filaments that are close to sunspots and along main polarity inversion line (PIL) with strong transverse field and magnetic shear, and the existence of a FR is usually predictable. In contrast, the present filament lies along the weak-field region (photospheric field strength $\\lesssim 100$ G), where the PIL is very fragmented due to small parasitic polarities on both side of the PIL and the transverse field has a low value of signal-to-noise ratio. Thus it represents a far more difficult challenge to extrapolate a large-sc...

Jiang, Chaowei; Feng, Xueshang; Hu, Qiang

2014-01-01

327

Identification of the viscoelastic properties of soft materials at low frequency: performance, ill-conditioning and extrapolation capabilities of fractional and exponential models.  

Science.gov (United States)

We report about the experimental identification of viscoelastic constitutive models for frequencies ranging within 0-10Hz. Dynamic moduli data are fitted forseveral materials of interest to medical applications: liver tissue (Chatelin et al., 2011), bioadhesive gel (Andrews et al., 2005), spleen tissue (Nicolle et al., 2012) and synthetic elastomer (Osanaiye, 1996). These materials actually represent a rather wide class of soft viscoelastic materials which are usually subjected to low frequencies deformations. We also provide prescriptions for the correct extrapolation of the material behavior at higher frequencies. Indeed, while experimental tests are more easily carried out at low frequency, the identified viscoelastic models are often used outside the frequency range of the actual test. We consider two different classes of models according to their relaxation function: Debye models, whose kernel decays exponentially fast, and fractional models, including Cole-Cole, Davidson-Cole, Nutting and Havriliak-Negami, characterized by a slower decay rate of the material memory. Candidate constitutive models are hence rated according to the accurateness of the identification and to their robustness to extrapolation. It is shown that all kernels whose decay rate is too fast lead to a poor fitting and high errors when the material behavior is extrapolated to broader frequency ranges. PMID:24967977

Ciambella, J; Paolone, A; Vidoli, S

2014-09-01

328

Grafting of HEMA onto dopamine coated stainless steel by 60Co-? irradiation method  

Science.gov (United States)

A novel method for grafting of 2-hydroxyethyl methacrylate (HEMA) onto the surface of stainless steel (SS) was explored by using 60Co-? irradiation. The surface of SS was modified by coating of dopamine before radiation grafting. The grafting reaction was performed in a simultaneous irradiation condition. The chemical structures change of the surface before and after grafting was demonstrated by Fourier transform infrared (FTIR) spectrometer. The hydrophilicity of the samples was determined by water contact angle measurement in the comparison of the stainless steel in the conditions of pristine, dopamine coated and HEMA grafted. Surface morphology of the samples was characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). The corrosion resistance properties of the samples were evaluated by Tafel polarization curve. The hemocompatibility of the samples were tested by platelet adhesion assay.

Jin, Wanqin; Yang, Liming; Yang, Wei; Chen, Bin; Chen, Jie

2014-12-01

329

Extrapolating surface structures to depth in transpressional systems: the role of rheology and convergence angle deduced from analogue experiments  

Science.gov (United States)

The internal structure of major strike-slip faults is still poorly understood, particularly how the deep structure could be inferred from its surface expression (Molnar and Dayem, 2011 and references therein). Previous analogue experiments suggest that the convergence angle is the most influential factor (Leever et al., 2011). Further analogue modeling may allow a better understanding how to extrapolate surface structures to the subsurface geometry of strike-slip faults. Various scenarios of analogue experiments were designed to represent strike-slip faults in nature from different geological settings. As such key parameters, which are investigated in this study include: (a) the angle of convergence, (b) the thickness of brittle layer, (c) the influence of a rheological weak layer within the crust, and (d) influence of a thick and rheologically weak layer at the base of the crust. The latter aimed to simulate the effect of a hot metamorphic core complex or an alignment of uprising plutons bordered by a transtensional/transpressional strike-slip fault. The experiments are aimed to explain first order structures along major transcurrent strike-slip faults such as the Altyn, Kunlun, San Andrea and Greendale (Darfield earthquake 2010) faults. The preliminary results show that convergence angle significantly influences the overall geometry of the transpressive system with greater convergence angles resulting in wider fault zones and higher elevation. Different positions, densities and viscosities of weak rheological layers have not only different surface expressions but also affect the fault geometry in the subsurface. For instance, rheological weak material in the bottom layer results in stretching when experiment reaches a certain displacement and a buildup of a less segmented, wide positive flower structure. At the surface, a wide fault valley in the middle of the fault zone is the reflection of stretching along the velocity discontinuity at depth. In models with a thin and rheologically weaker layer in the middle of the brittle layer, deformation is distributed over more faults and the geometry of the fault zone below and above the weak zone shows significant differences, suggesting that the correlation of structures across a weak layer has to be supported by geophysical data, which help constraining the geometry of the deep part. This latter experiment has significantly similar phenomena in reality, such as few pressure ridges along Altyn fault. The experimental results underline the need to understand the role of the convergence angle and the influence of rheology on fault evolution, in order to connect between surface deformation and subsurface geometry. References Leever, K. A., Gabrielsen, R. H., Sokoutis, D., Willingshofer, E., 2011. The effect of convergence angle on the kinematic evolution of strain partitioning in transpressional brittle wedges: Insight from analog modeling and high-resolution digital image analysis. Tectonics, 30(2), TC2013. Molnar, P., Dayem, K.E., 2010. Major intracontinental strike-slip faults and contrasts in lithospheric strength. Geosphere, 6, 444-467.

Hsieh, Shang Yu; Neubauer, Franz; Cloetingh, Sierd; Willingshofer, Ernst; Sokoutis, Dimitrios

2014-05-01

330

Adverse Outcome Pathways and Systems Biology as Conceptual Approaches to Support Development of 21st Century Test Methods and Extrapolation Tools  

Science.gov (United States)

The proposed paradigm for ?Toxicity Testing in the 21st Century? supports the development of mechanistically-based, high-throughput in vitro assays as a potential cost effective and scientifically-sound alternative to some whole animal hazard testing. To accomplish this long-term...

331

The Magnetic Field of Active Region 11158 During the 2011 February 12-17 Flares : Differences between Photospheric Extrapolation and Coronal Forward-Fitting Methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We developed a {\\sl coronal non-linear force-free field (COR-NLFFF)} forward-fitting code that fits an approximate {\\sl non-linear force-free field (NLFFF)} solution to the observed geometry of automatically traced coronal loops. In contrast to photospheric NLFFF codes, which calculate a magnetic field solution from the constraints of the transverse photospheric field, this new code uses coronal constraints instead, and this way provides important information on systematic e...

Aschwanden, Markus J.; Sun, Xudong; Liu, Yang

2014-01-01

332

Measurement of extrapolation curves for the secondary pattern of beta radiation Nr. 86 calibrated in rapidity of absorbed dose for tissue equivalent by the Physikalisch Technische Bundesanstalt  

International Nuclear Information System (INIS)

The following report has as objective to present the obtained results of measuring - with a camera of extrapolation of variable electrodes (CE) - the dose speed absorbed in equivalent fabric given by the group of sources of the secondary pattern of radiation Beta Nr. 86, (PSB), and to compare this results with those presented by the calibration certificates that accompany the PSB extended by the primary laboratory Physikalisch Technische Bundesanstalt, (PTB), of the R.F.A. as well as the uncertainties associated to the measure process. (Author)

333

Measurement of very low oxygen tensions in liquids: does the extrapolation number for mammalian survival curves decrease after x-irradiation under anoxic conditions  

International Nuclear Information System (INIS)

Measurements of very low partial pressures of oxygen show that a vacuum degassing system combined with an oxygen consuming agent (sodium dithionite) and/or radiochemical oxygen consumption removes all of the oxygen from cells plated on glass dishes. When these cells are x-irradiated, the extrapolation number n remains the same under both aerobic and anoxic conditions, and an oxygen enhancement ratio of 3.0 is observed. Several other physical and chemical factors tested also have no effect on n. (author)

334

Raffaels Astronomische Tafel entschlüsselt - Kopernikanisches Weltsystem und Jupitermonde in Raffaels Schule von Athen (1509-14)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The analysis of the Astronomical Table in Raphael´s School of Athens shows that the "crayon-drawing" is based on Copernicus´ Commentariolus, the first textual document of the modern era. For its visualization Raphael used triangles and arithmetic fractions. After Giorgione did before, he also succeeded in discovering the four Jupiter satellites which he had depicted in the fresco as the mythic figures Callisto, Arcas, Io and Epaphus.

Keim, Frank

2014-01-01

335

Raffaels Astronomische Tafel entschlüsselt - Kopernikanisches Weltsystem und Jupitermonde in Raffaels Schule von Athen (1509-14)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The analysis of the Astronomical Table in Raphaels School of Athens shows that the "crayon-drawing" is based on Copernicus’ Commentariolus, the first textual document of the modern era. For its visualization Raphael used triangles and arithmetic fractions. After Giorgione did before, he also succeeded in discovering the four Jupiter satellites which he had depicted in the fresco as the mythic figures Callisto, Arcas, Io and Epaphus.

Keim, Frank

2013-01-01

336

‘Als de tafel danst, dan wankelt de wetenschap’. De relatie tussen spiritisme en wetenschap rond 1900  

Directory of Open Access Journals (Sweden)

Full Text Available

'If the table turns, science will stagger'. The relationship between spiritualism and science in the Netherlands around 1900


Spiritualism is the belief that living men can keep contact, usually through an intermediary called a 'medium', with spirits of the dead. The history of modern spiritualism started in 1848 in America and in the decades that followed it spread all over the world. Especially as a result of British influences modern Anglo-Saxon spiritualism is characterized by a search for scientific proof of the so-called spiritualist phenomena. In the 1920s the Netherlands were late in comparison with neighbouring countries to institutionalize the scientific study of these phenomena. But this does not imply that there was no earlier discussion about it. Indeed, around 1900 there were attempts for a debate about the scientific underpinning of spiritualism and the main stage for it was the journal Het toekomstig leven [The future life]. In the historical conceptualization of this debate it has long been common to see the spiritualists as an anti-modern counterculture and the scientists as the representatives of modernity. Recently this dichotomic order has been replaced for a nuanced view that does more justice to the historical reality. Although Het toekomstig leven often used rhetoric strategies that emphasized the confrontation with science, the journal also lavishly incorporated scientific elements and made inexhaustible attempts for a scientific debate and study of the paranormal phenomena. Unlike in neighbouring countries there were hardly any natural scientists who responded, but there were some physicians as well as pioneers of the new field of parapsychology who pleaded for scientific research of spiritualism. This research eventually became reality in 1920 under the direction of some heavyweight scientists, but just as Het toekomstig leven the Dutch Society for Psychical Research was also marked by the difference between the critical-scientific approach and the not so critical approach of the believers. In my contribution I have showed that this demarcation was however not the same as the one between science and spiritualism, because these boundaries were considerably permeable.

Leonieke Vermeer

2007-01-01

337

Mathematical methods for physical and analytical chemistry  

CERN Document Server

Mathematical Methods for Physical and Analytical Chemistry presents mathematical and statistical methods to students of chemistry at the intermediate, post-calculus level. The content includes a review of general calculus; a review of numerical techniques often omitted from calculus courses, such as cubic splines and Newton's method; a detailed treatment of statistical methods for experimental data analysis; complex numbers; extrapolation; linear algebra; and differential equations. With numerous example problems and helpful anecdotes, this text gives chemistry students the mathematical

Goodson, David Z

2011-01-01

338

Evolution of the N=50 gap from Z=30 to Z=38 and extrapolation towards 78Ni  

CERN Document Server

The evolution of the N=50 gap is analyzed as a function of the occupation of the proton f5/2 and p3/2 orbits. It is based on experimental atomic masses, using three different methods of one or two-neutron separation energies of ground or isomeric states. We show that the effect of correlations, which is maximized at Z=32 could be misleading with respect to the determination of the size of the shell gap, especially when using the method with two-neutron separation energies. From the methods that are the least perturbed by correlations, we estimate the N=50 spherical shell gap in 78Ni. Whether 78Ni would be a rigid spherical or deformed nucleus is discussed in comparison with other nuclei in which similar nucleon-nucleon forces are at play.

Porquet, M -G

2012-01-01

339

Copper complex N(4)-ortho-toluyl-2-acetylpyridine thiosemicarbazone - (64Cu)(H2Ac4oT)Cl - internal dosimetry: animal model and human extrapolation  

International Nuclear Information System (INIS)

Thiosemicarbazones have attracted great pharmacological interest because of their biological properties, such as cytotoxic activity against multiple strains of human tumors. Due to the excellent properties of 64Cu, the copper complex N(4)-ortho-toluyl-2-acetylpyridine thiosemicarbazone ( (64Cu)(H2Ac4oT)Cl) was developed for tumor detection by positron emission tomography. The radiopharmaceuticals were produced in the nuclear reactor TRIGA-IPR-R1 from CDTN. At the present work, (64Cu)(H2Ac4oT)Cl biokinetic data (evaluated in mice bearing Ehrlich tumor) were treated by MIRD formalism to perform Internal Dosimetry studies. Doses in several organs of mice were determinate, as well as in implanted tumor, for (64Cu)(H2Ac4oT)Cl. Doses results obtained for animal model were extrapolated to humans assuming a similar concentration ratio among various tissues between mouse and human. In the extrapolation, it was used human organ masses from Cristy/Eckerman phantom. Both penetrating and non-penetrating radiation from 64Cu in the tissue were considered in dose calculations. (author)

340

Creep-rupture-tests on thestainless steel X6 CrNi1811 (DIN 1.4948) in the frame of the ''Extrapolation-Program'' Pt. 2  

International Nuclear Information System (INIS)

The austenitic stainless steel X6 CrNi 1811 (DIN 1.4948) that is used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-650 deg under base material condition as well as welded material condition. The main point of this program (''Extrapolation-Program'') lies in the knowledge of the cree-rupture-strength and creep-behaviour up to 3X10-4 hours at higher temperatures in order to extrapolate up to (>=)105 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out over temperature range 550 deg - 750 deg C. The present report describes the state in the running program with test-time up to 35.000 hours. Besides the cree-rupture behaviour it is possible to make a distinct quantitative statement for the creep-behaviour and ductility. Extensive metallographic examinations show the fracture behaviour and changes in structure. (author)

 
 
 
 
341

Irradiation dose assessment in persons exposed to ionizing radiation through extrapolation of data from clinic-chemical changes in irradiated laboratory animals  

International Nuclear Information System (INIS)

An attempt is made to determine the dose within 24,48 and 72 hours of eventual exposure of healthy individuals to ionizing radiation through extrapolation of data retrieved from rats exposed to irradiation with 1, 3, 6 and 9 Gy X-rays. Seven clinic-chemical parameters are used: urea in the urine, taurine in the urine, urea in the serum, serum alkaline phosphatase, total serum lipids, sialic acid and thromboxane in the serum. A special formula is worked out and used for extrapolation of the experimental data, retrieved from irradiated rats, with due consideration to differences in the intensity of metabolic processes and species' radiosensitivity of rats and humans. The values of the aforementioned parameters that could be obtained upon eventual exposure of persons to ionizing irradiation are determined through computerization of the experimental data. It is believed that an accessible model for radiation dose assessment in the first three days after accidental exposure of human beings to ionizing irradiation is created. 5 refs., 4 figs. (author)

342

Kinetic modeling of ?-chloroprene metabolism: Probabilistic in vitro-in vivo extrapolation of metabolism in the lung, liver and kidneys of mice, rats and humans.  

Science.gov (United States)

?-Chloroprene (chloroprene) is carcinogenic in inhalation bioassays with B6C3F1 mice and Fischer rats, but the potential effects in humans have not been adequately characterized. In order to provide a better basis for evaluating chloroprene exposures and potential effects in humans, we have explored species and tissue differences in chloroprene metabolism. This study implemented an in vitro-in vivo extrapolation (IVIVE) approach to parameterize a physiologically based pharmacokinetic (PBPK) model for chloroprene and evaluate the influence of species and gender differences in metabolism on target tissue dosimetry. Chloroprene metabolism was determined in vitro using liver, lung and kidney microsomes from male or female mice, rats, and humans. A two compartment PK model was used to estimate metabolism parameters for chloroprene in an in vitro closed vial system, which were then extrapolated to the whole body PBPK model. Two different strategies were used to estimate parameters for the oxidative metabolism of chloroprene: a deterministic point-estimation using the Nelder-Mead nonlinear optimization algorithm and probabilistic Bayesian analysis using the Markov Chain Monte Carlo technique. Target tissue dosimetry (average amount of chloroprene metabolized in lung per day) was simulated with the PBPK model using the in vitro-based metabolism parameters. The model-predicted target tissue dosimetry, as a surrogate for a risk estimate, was similar between the two approaches; however, the latter approach provided a measure of uncertainty in the metabolism parameters and the opportunity to evaluate the impact of that uncertainty on predicted risk estimates. PMID:22543297

Yang, Yuching; Himmelstein, Matthew W; Clewell, Harvey J

2012-09-01

343

A Method for Specific Activity Measurement of 241Am Solution  

International Nuclear Information System (INIS)

According to the principle of coincidence theory, the specific activity of 241Am solution was determined on 4??+4?? counting standard device by ? efficiency extrapolation, and the problems of constant correction coefficients of self-absorption and scattering in ? ionization chamber method were solved. The method was based on the alteration of detection efficiency when the height of elevator was altered, and the activity was obtained by ? fitting extrapolation according to detection efficiency. The results of more than 20 alpha radioactive sources by this method in our work are accordant with those of 2?? ionization chamber, and their uncertainties are improved to 0.4%. (authors)

344

The assessment of errors in past radiation doses extrapolated from ESR/TL dose-response data  

Energy Technology Data Exchange (ETDEWEB)

We employ a method for generating dose-response data artificially in which each response is computed as the sum of a saturating exponential function and a random error. Data sets generated in this way are used to check two computing strategies, straight line conversion and the simplex procedure, and to investigate the optimal distribution of data points, and the role of the selection of correct weights for the fitting of the data sets. Additionally, three methods for error estimation are tested: the analytical expression, jack-knifing and Monte Carlo simulation. Jack-knifing turns out to be the least suitable technique for error estimation of ESR/TL dose-response data. (Author).

Grun, R. [Australian National Univ., Canberra, ACT (Australia); Brumby, S. [Australian National Univ., Canberra, ACT (Australia). Research School of Chemistry

1994-04-01

345

Mapping coexistence lines via free-energy extrapolation: Application to order-disorder phase transitions of hard-core mixtures  

Science.gov (United States)

In this work, a variant of the Gibbs-Duhem integration (GDI) method is proposed to trace phase coexistence lines that combines some of the advantages of the original GDI methods such as robustness in handling large system sizes, with the ability of histogram-based methods (but without using histograms) to estimate free-energies and hence avoid the need of on-the-fly corrector schemes. This is done by fitting to an appropriate polynomial function not the coexistence curve itself (as in GDI schemes) but the underlying free-energy function of each phase. The availability of a free-energy model allows the post-processing of the simulated data to obtain improved estimates of the coexistence line. The proposed method is used to elucidate the phase behavior for two non-trivial hard-core mixtures: a binary blend of spheres and cubes and a system of size-polydisperse cubes. The relative size of the spheres and cubes in the first mixture is chosen such that the resulting eutectic pressure-composition phase diagram is nearly symmetric in that the maximum solubility of cubes in the sphere-rich solid (˜20%) is comparable to the maximum solubility of spheres in the cube-rich solid. In the polydisperse cube system, the solid-liquid coexistence line is mapped out for an imposed Gaussian activity distribution, which produces near-Gaussian particle-size distributions in each phase. A terminal polydispersity of 11.3% is found, beyond which the cubic solid phase would not be stable, and near which significant size fractionation between the solid and isotropic phases is predicted.

Escobedo, Fernando A.

2014-03-01

346

Lits fluidisés pour l'industrie chimique. Extrapolation et amélioration des catalyseurs. Première partie : Etudes et modèles. Enseignements issus des pilotes Fluidized Beds in Chemical Industry. Scale Up and Catalysts Improvement. First Part: Studies, Models, Learning from Pilot Plants  

Directory of Open Access Journals (Sweden)

Full Text Available Les unités de production en lits fluidisés catalytiques sont apparues vers 1942 dans l'industrie pétrolière et vers 1960 dans l'industrie chimique. On se limitera ici au problème de l'extrapolation des lits fluidisés catalytiques pour l'industrie chimique, qui exigent de très hautes performances (> 99 % de conversion. Leur mise au point a, dans le passé, nécessité l'exploitation sur des sites industriels de coûteux pilotes de 0,5 m de diamètre et de plus de 10 m de hauteur. Nous montrerons que ces pilotes peuvent être évités et que le passage direct du laboratoire à l'échelle industrielle est réalisable. Cette possibilité offre en plus une méthode simple pour améliorer les catalyseurs des unités industrielles. Elle ouvre aussi cette technique, très appréciée en production, aux produits de petits tonnages. La présentation de cet article sera faite en trois parties : - La première, présentée ci-après, expose les problèmes majeurs posés par l'extrapolation, puis résume les études effectuées. Les travaux d'extrapolation relatifs à deux procédés effectués avec des pilotes sont ensuite présentés, à titre d'exemples. De ces travaux sont déduites les performances que l'on peut espérer obtenir avec un réacteur catalytique à lit fluidisé, ainsi que les règles de tendances à suivre pour y parvenir. - La deuxième partie, intitulée Stratégie n'utilisant que des expériences de laboratoire , propose une stratégie expérimentale permettant d'obtenir en laboratoire les informations nécessaires pour passer directement à l'échelle industrielle avec des expériences suggérées en partie par les résultats exposés dans le premier article. Les relations expérimentales établies lors de ces études montrent que les propriétés d'un lit fluidisé ne dépendent (mis à part quelquefois le diamètre du réacteur que d'un paramètre appelé vitesse minimum de fluidisation de comportement . - La troisième partie est intitulée Études théoriques, réalités expérimentales, suggestions . Les bulles des lits fluidisés ont fait l'objet de très nombreux travaux, dont les résultats sont très souvent explicités sous la forme de modèles mécanistiques à un paramètre qui est le diamètre des bulles. Pour confronter ces modèles à l'expérience, une relation est établie entre le diamètre des bulles et la vitesse minimum de fluidisation de comportement. Des suggestions sont alors faites pour améliorer les modèles, et l'on propose des conclusions générales sur les lits fluidisés. The firsts catalytic fluidized beds appear near 1942 in petroleum industry and near 1960 in chemical industry. We only consider very high performances chemical fluidized bed reactors (> 99%. In the past, they were developed through the use of very expensive pilot plants of about 0. 5 m diameter and 10 in high. We will demonstrate that direct scale up from laboratory data is possible. This possibility gives also a simple method to improve catalysts used into operating units and opens fluidized bed technique to products that need only low production. Presentation is made with three articles:- In the first, Studies, Models, Learning from Pilot Plants : after a description of the major scale-up problems, studies to solve then are summarized. Then scale-up works of two processes with the use of about 0. 5 m diameter pilot plant are given. From the results it is deduced the possible performances of a catalytic fluidized bed and how to operate to obtain then. - In the second*, Scale up with Only Laboratory Data , it is experimentally demonstrated that the information's scale-up can be obtained in a laboratory. A strategy to obtain them is suggested. An another result of theses experimental studies is that all physical properties of catalytic fluidized bed depends of only one parameter. It is called comportment incipient fluidization velocity . - In the third*, Theoretical Studies, Experimental Reality, Suggestionsresults of theoretical studies about bubbles of the fluidized beds are summarize

Botton R.

2006-12-01

347

Corrosion Behaviour of 18%Ni M250 Grade Maraging Steel under Welded Condition in Hydrochloric Acid Medium  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in english The corrosion behaviour of welded maraging steel in hydrochloric acid solutions was studied over a range of acid concentration and solution temperature by electrochemical techniques like Tafel extrapolation method and electrochemical impedance spectroscopy. The corrosion rate of welded maraging stee [...] l increases with the increase in temperature and concentration of hydrochloric acid in the medium. The energies of activation, enthalpy of activation and entropy of activation for the corrosion process were calculated. The surface morphology of the corroded sample was evaluated by surface examination using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).

Pradeep, Kumar; A. Nityananda, Shetty.

2013-01-01

348

Corrosion inhibition of brass by aliphatic amines  

International Nuclear Information System (INIS)

Aliphatic amines hexylamine (HCA), octylamine (OCA) and decylamine (DCA) have been used as corrosion inhibitors for (70/30) brass in 0.I M HCIO4. The inhibitor efficiency (%P) calculated using weight loss, Tafel extrapolation, linear polarization and impedance methods was found to be in the order DCA> OCA> HCA. These adsorb on brass surface following bockris-swinkels' isotherm. DCA, OCA and HCA displaced 4, 3 and 2 molecules of water from interface respectively. Displacement of water molecules brought a great reorganization of double layer at the interface. These amines during corrosion form complexes with dissolved zinc and copper ions.(Author)

349

Corrosion Behaviour of 18%Ni M250 Grade Maraging Steel under Welded Condition in Hydrochloric Acid Medium  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in english The corrosion behaviour of welded maraging steel in hydrochloric acid solutions was studied over a range of acid concentration and solution temperature by electrochemical techniques like Tafel extrapolation method and electrochemical impedance spectroscopy. The corrosion rate of welded maraging stee [...] l increases with the increase in temperature and concentration of hydrochloric acid in the medium. The energies of activation, enthalpy of activation and entropy of activation for the corrosion process were calculated. The surface morphology of the corroded sample was evaluated by surface examination using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).

Pradeep, Kumar; A. Nityananda, Shetty.

350

Extrapolating active layer thickness measurements across Arctic polygonal terrain using LiDAR and NDVI data sets  

Science.gov (United States)

attributes that vary with microtopography, such as active layer thickness (ALT), are labor intensive and difficult to document effectively through in situ methods at kilometer spatial extents, thus rendering remotely sensed methods desirable. Spatially explicit estimates of ALT can provide critically needed data for parameterization, initialization, and evaluation of Arctic terrestrial models. In this work, we demonstrate a new approach using high-resolution remotely sensed data for estimating centimeter-scale ALT in a 5 km2 area of ice-wedge polygon terrain in Barrow, Alaska. We use a simple regression-based, machine learning data-fusion algorithm that uses topographic and spectral metrics derived from multisensor data (LiDAR and WorldView-2) to estimate ALT (2 m spatial resolution) across the study area. Comparison of the ALT estimates with ground-based measurements, indicates the accuracy (r2 = 0.76, RMSE ±4.4 cm) of the approach. While it is generally accepted that broad climatic variability associated with increasing air temperature will govern the regional averages of ALT, consistent with prior studies, our findings using high-resolution LiDAR and WorldView-2 data, show that smaller-scale variability in ALT is controlled by local eco-hydro-geomorphic factors. This work demonstrates a path forward for mapping ALT at high spatial resolution and across sufficiently large regions for improved understanding and predictions of coupled dynamics among permafrost, hydrology, and land-surface processes from readily available remote sensing data.

Gangodagamage, Chandana; Rowland, Joel C.; Hubbard, Susan S.; Brumby, Steven P.; Liljedahl, Anna K.; Wainwright, Haruko; Wilson, Cathy J.; Altmann, Garrett L.; Dafflon, Baptiste; Peterson, John; Ulrich, Craig; Tweedie, Craig E.; Wullschleger, Stan D.

2014-08-01

351

Comparative studies of parameters based on the most probable versus an approximate linear extrapolation distance estimates for circular cylindrical absorbing rod  

International Nuclear Information System (INIS)

Estimates and techniques that are valid to calculate the linear extrapolation distance for an infinitely long circular cylindrical absorbing region are reviewed. Two estimates, in particular, are put into consideration, that is the most probable and the value resulting from an approximate technique based on matching the integral transport equation inside the absorber with the diffusion approximation in the surrounding infinite scattering medium. Consequently, the effective diffusion parameters and the blackness of the cylinder are derived and subjected to comparative studies. A computer code is set up to calculate and compare the different parameters, which is useful in reactor analysis and serves to establish a beneficial estimates that are amenable to direct application to reactor design codes

352

Precision ground state mass of 12Be and an isobaric multiplet mass equation (IMME) extrapolation for 2+ and 02+ states in the T=2, A=12 multiplet  

International Nuclear Information System (INIS)

We report the mass measurement of the short-lived 12Be nuclide (T1/2=21.5 ms) performed using the Penning trap mass spectrometer TITAN at TRIUMF. Our mass excess value of 25 078.0(2.1) keV is in agreement with previous measurements, but is a factor of 7 more precise than the Atomic Mass Evaluation of 2003. To address an unresolved discussion on the spin assignment of isospin T=2 states in 12C and 12O, we reevaluate the isobaric mass multiplet equation for the lowest lying T=2 multiplet in the A=12 system and use the extracted parameters to extrapolate from the known excited 2+ and 0+ states in 12Be. Though this analysis favors the second known T=2 state in 12C to be 2+, 0+ cannot be excluded.

353

Extrapolation of data from simulant-material experiments to the work potential of fuel penetrating through upper core structures in core disruptive accidents  

International Nuclear Information System (INIS)

This report addresses questions that arose after having completed a detailed study of a simulant-material experimental investigation of flow dynamics in the Upper Core Structures during a Core Disruptive Accident of a Liquid-Metal Fast Breeder Reactor. The main findings of the experiments were about the reduction of work potential of the expanding fuel by the presence of the Upper Core Structures. This report describes how the experimental data can be extrapolated to prototypic conditions, which phenomena modelled in code predictions by SIMMER-II are different for simulant and prototypic transients, and how the experimental results compare to effects of prototypic phenomena which could not be modelled in the experiment. (orig.)

354

Modeling the systemic retention of beryllium in rat. Extrapolation to human; Modelizacion de la retencion sistemica del berilio en la rata. Extrapolacion al Hombre  

Energy Technology Data Exchange (ETDEWEB)

In this work, we analyzed different approaches, assayed in order to numerically describe the systemic behaviour of Beryllium. The experimental results used in this work, were previously obtained by Furchner et al. (1973), using Sprague-Dawley rats, and others animal species. Furchner's work includes the obtained model for whole body retention in rats, but not for each target organ. In this work we present the results obtained by modeling the kinetic behaviour of Beryllium in several target organs. The results of this kind of models were used in order to establish correlations among the estimated kinetic constants. The parameters of the model were extrapolated to humans and, finally, compared with others previously published. (Author) 12 refs.

Montero Prieto, M.; Vidania Munoz, R. de

1994-07-01

355

Physiologically based pharmacokinetics joined with in vitro-in vivo extrapolation of ADME: a marriage under the arch of systems pharmacology.  

Science.gov (United States)

Classic pharmacokinetics (PK) rarely takes into account the full knowledge of physiology and biology of the human body. However, physiologically based PK (PBPK) is built mainly from drug-independent "system" information. PBPK is not a new concept, but it has shown a very rapid rise in recent years. This has been attributed to a greater connectivity to in vitro-in vivo extrapolation (IVIVE) techniques for predicting drug absorption, distribution, metabolism, and excretion (ADME) and their variability in humans. The marriage between PBPK and IVIVE under the overarching umbrella of "systems biology" has removed many constraints related to cutoff approaches on prediction of ADME. PBPK-IVIVE linked models have repeatedly shown their value in guiding decisions when predicting the effects of intrinsic and extrinsic factors on PK of drugs. A review of the achievements and shortcomings of the models might suggest better strategies in extending the success of PBPK-IVIVE to pharmacodynamics (PD) and drug safety. PMID:22644330

Rostami-Hodjegan, A

2012-07-01

356

Extrapolating ecotoxicological effects from individuals to populations: a generic approach based on Dynamic Energy Budget theory and individual-based modeling.  

Science.gov (United States)

Individual-based models (IBMs) predict how dynamics at higher levels of biological organization emerge from individual-level processes. This makes them a particularly useful tool for ecotoxicology, where the effects of toxicants are measured at the individual level but protection goals are often aimed at the population level or higher. However, one drawback of IBMs is that they require significant effort and data to design for each species. A solution would be to develop IBMs for chemical risk assessment that are based on generic individual-level models and theory. Here we show how one generic theory, Dynamic Energy Budget (DEB) theory, can be used to extrapolate the effect of toxicants measured at the individual level to effects on population dynamics. DEB is based on first principles in bioenergetics and uses a common model structure to model all species. Parameterization for a certain species is done at the individual level and allows to predict population-level effects of toxicants for a wide range of environmental conditions and toxicant concentrations. We present the general approach, which in principle can be used for all animal species, and give an example using Daphnia magna exposed to 3,4-dichloroaniline. We conclude that our generic approach holds great potential for standardized ecological risk assessment based on ecological models. Currently, available data from standard tests can directly be used for parameterization under certain circumstances, but with limited extra effort standard tests at the individual would deliver data that could considerably improve the applicability and precision of extrapolation to the population level. Specifically, the measurement of a toxicant's effect on growth in addition to reproduction, and presenting data over time as opposed to reporting a single EC50 or dose response curve at one time point. PMID:23430409

Martin, Benjamin T; Jager, Tjalling; Nisbet, Roger M; Preuss, Thomas G; Hammers-Wirtz, Monika; Grimm, Volker

2013-04-01

357

The Trojan horse method in nuclear astrophysics  

International Nuclear Information System (INIS)

Because of the Coulomb barrier, reaction cross sections in astrophysics cannot be accessed directly at the relevant Gamow energies, unless very favourable conditions are met (e.g. LUNA--underground experiments). Theoretical extrapolations of available data are then needed to derive the astrophysical S(0)-factor. Various indirect processes have been used in order to obtain additional information on the parameters entering these extrapolations. The Trojan Horse Method is an indirect method which might help to bypass some of the problems typically encountered in direct measurements, namely the presence of the Coulomb barrier and the effect of the electron screening. However, a comparison with direct data in an appropriate energy region (e.g. around the Coulomb barrier) is crucial before extending the method to the relevant Gamow energy. Additionally, experimental and theoretical tests are needed to validate the assumptions underlying the method. The application of the Trojan Horse Method to some cases of interest is discussed

358

Extrapolating EISCAT Pedersen conductances to other parts of the sky using ground-based TV auroral images  

Directory of Open Access Journals (Sweden)

Full Text Available Ionospheric conductivity is not very easily measured directly. Incoherent scatter radars perhaps offer the best method but can only measure at one point in the sky at any one time and are limited in their time resolution. Statistical models of average conductivity are available but these may not be applied to individual case studies such as substorms. There are many instances where a real-time estimate of ionospheric conductivity over a large field-of-view is highly desirable at a high temporal and spatial resolution. We show that it is possible to make a reasonable estimate of the noctural height-integrated Pedersen conductivity, or conductance, with a single all-sky TV camera operating at 557.7 nm. This is not so in the case of the Hall conductance where at least two auroral wavelengths should be imaged in order to estimate additionally the energy of the precipitating particles.

Key words. Atmospheric composition and structure (airglow and aurora · Magnetospheric physics (auroral phenomena · instruments and techniques

M. J. Kosch

359

Chiral extrapolation of light resonances from one and two-loop unitarized chiral perturbation theory versus lattice results  

Science.gov (United States)

We study the pion mass dependence of the ?(770) and f0(600) masses and widths from one and two-loop unitarized chiral perturbation theory (ChPT). We show the consistency of one-loop calculations with lattice results for the M?, f?, and the isospin-2 scattering length a20. Then, we develop and apply the modified inverse amplitude method formalism for two-loop ChPT. In contrast to the f0(600), the ?(770) is rather sensitive to the two-loop ChPT parameters—our main source of systematic uncertainty. We thus provide two-loop unitarized fits constrained by lattice information on M?, f?, by the qq¯ leading 1/Nc behavior of the ? and by existing estimates of low-energy constants. These fits yield relatively stable predictions up to m??300-350MeV for the ? coupling and width as well as for all the f0(600) parameters. We confirm, to two loops, the weak m? dependence of the ? coupling and the Kawarabayashi-Suzuki-Riazuddin-Fayyazuddin relation, and the existence of two virtual f0(600) poles for sufficiently high m?. At two loops one of these poles becomes a bound state when m? is somewhat larger than 300 MeV.

Peláez, J. R.; Ríos, G.

2010-12-01

360

Peptide models. XXXIII. Extrapolation of low-level Hartree-Fock data of peptide conformation to large basis set SCF, MP2, DFT, and CCSD(T) results. The Ramachandran surface of alanine dipeptide computed at various levels of theory.  

Science.gov (United States)

At the dawn of the new millenium, new concepts are required for a more profound understanding of protein structures. Together with NMR and X-ray-based 3D-structure determinations in silico methods are now widely accepted. Homology-based modeling studies, molecular dynamics methods, and quantum mechanical approaches are more commonly used. Despite the steady and exponential increase in computational power, high level ab initio methods will not be in common use for studying the structure and dynamics of large peptides and proteins in the near future. We are presenting here a novel approach, in which low- and medium-level ab initio energy results are scaled, thus extrapolating to a higher level of information. This scaling is of special significance, because we observed previously on molecular properties such as energy, chemical shielding data, etc., determined at a higher theoretical level, do correlate better with experimental data, than those originating from lower theoretical treatments. The Ramachandran surface of an alanine dipeptide now determined at six different levels of theory [RHF and B3LYP 3-21G, 6-31+G(d) and 6-311++G(d,p)] serves as a suitable test. Minima, first-order critical points and partially optimized structures, determined at different levels of theory (SCF, DFT), were completed with high level energy calculations such as MP2, MP4D, and CCSD(T). For the first time three different CCSD(T) sets of energies were determined for all stable B3LYP/6-311++G(d,p) minima of an alanine dipeptide. From the simplest ab initio data (e.g., RHF/3-21G) to more complex results [CCSD(T)/6-311+G(d,p)//B3LYP/6-311++G(d,p)] all data sets were compared, analyzed in a comprehensive manner, and evaluated by means of statistics. PMID:12759903

Perczel, András; Farkas, Odön; Jákli, Imre; Topol, Igor A; Csizmadia, Imre G

2003-07-15

 
 
 
 
361

Extrapolating Ground-Based Aircraft Engine Exhaust Emissions to Cruise Conditions: Lessons From the 2013 ACCESS Chase Plane Experiment  

Science.gov (United States)

Aircraft engine emissions constitute a tiny fraction of the global black carbon mass, but can have a disproportionate climatic impact because they are emitted high in the troposphere and in remote regions with otherwise low aerosol concentrations. Consequently, these particles are likely to strongly influence cirrus and contrail formation by acting as ice nuclei (IN). However, the ice nucleating properties of aircraft exhaust at relevant atmospheric conditions are not well known, and thus, the overall impact of aviation on cloud formation remains very uncertain. While a number of aircraft engine emissions studies have previously been conducted at sea level temperature and pressure (e.g., APEX, AAFEX-1 and 2), it unclear the extent to which exhaust emissions on the ground translate to emissions at cruise conditions with much lower inlet gas temperatures and pressures. To address this need, the NASA Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) was conducted in February-April, 2013 to examine the aerosol and gas emissions from the NASA DC-8 under a variety of different fuel types, engine power, and altitude/meteorological conditions. Two different fuel types were studied: a traditional JP-8 fuel and a 50:50 blend of JP-8 and a camelina-based hydro-treated renewable jet (HRJ) fuel. Emissions were sampled using a comprehensive suite of gas- and aerosol-phase instrumentation integrated on an HU-25 Falcon jet that was positioned in the DC-8 exhaust plume at approximately 100-500m distance behind the engines. In addition, a four-hour ground test was carried out with sample probes positioned at 30 m behind each of the inboard engines. Measurements of aerosol concentration, size distribution, soot mass, and hygroscopicity were carried out along with trace gas measurements of CO2, NO, NO2, O3, and water vapor. NOx emissions were reconciled by employing the well-established Boeing method for normalizing engine fuel flow rates to STP; however, comparison of aerosol emissions between ground and altitude is less straight forward. The implications of these factors for developing new aviation emissions factors / inventories related to aerosol species will be discussed.

Moore, R.; Shook, M.; Thornhill, K. L.; Winstead, E.; Anderson, B. E.

2013-12-01

362

HIV infection in older adults in sub-Saharan Africa: extrapolating prevalence from existing data / Infection à VIH chez les adultes âgés en Afrique subsaharienne: extrapolation de la prévalence à partir de données existantes / Infección por el VIH entre los adultos de mayor edad en el África subsahariana: extrapolación de la prevalencia a partir de los datos existentes  

Scientific Electronic Library Online (English)

Full Text Available SciELO Public Health | Language: English Abstract in spanish OBJETIVO: Cuantificar el número de casos y la prevalencia de la infección por el virus de la inmunodeficiencia humana (VIH) entre los adultos de mayor edad en el África subsahariana. MÉTODOS: Se han analizado los datos procedentes de las Encuestas demográficas y de salud (EDS). Aunque en estos estud [...] ios todas las mujeres entrevistadas son menores de 50 años, 18 de estas encuestas contenían datos sobre la infección por VIH en hombres con una edad igual o superior a los 50 años. Para calcular el porcentaje de adultos de mayor edad (es decir, personas de 50 o más años de edad) con positividad al VIH (VIH+), se extrapolaron los datos procedentes del Programa Conjunto de las Naciones Unidas sobre el VIH/SIDA sobre la cantidad estimada de personas con el VIH y sobre la prevalencia de la infección por este virus entre los adultos con edades comprendidas entre 15 y 49 años. RESULTADOS: En 2007, en el África subsahariana había unos 3 millones de personas de 50 años o mayores con el VIH. La prevalencia de la infección por el VIH en este grupo fue del 4,0%, en comparación con el 5,0% correspondiente al grupo con edades comprendidas entre 15 y 49 años. De la cantidad aproximada de 21 millones de personas > 15 años con VIH en el África subsahariana, el 14,3% tenía 50 años de edad o más. CONCLUSIÓN: Para poder reflejar mejor la mayor supervivencia de las personas con VIH y el envejecimiento de la población VIH+, se deben ampliar los indicadores de la prevalencia de la infección por el VIH, de manera que incluyan a las personas mayores de 49 años. Se sabe poco sobre la morbilidad asociada y el comportamiento sexual de los adultos VIH+ de mayor edad o acerca de los factores biológicos y culturales que aumentan el riesgo de transmisión. Los servicios relacionados con el VIH deben orientarse mejor para responder a las necesidades crecientes de los adultos de edad más avanzada que se ven afectados por esta enfermedad. Abstract in english OBJECTIVE: To quantify the number of cases and prevalence of human immunodeficiency virus (HIV) infection among older adults in sub-Saharan Africa. METHODS: We reviewed data from Demographic and Health Surveys (DHS). Although in these surveys all female respondents are [...] urveys contained data on HIV infection among men aged > 50 years. To estimate the percentage of older adults (i.e. people > 50 years of age) who were positive for HIV (HIV+), we extrapolated from data from the Joint United Nations Programme on HIV/AIDS on the estimated number of people living with HIV and on HIV infection prevalence among adults aged 15-49 years. FINDINGS: In 2007, approximately 3 million people aged > 50 years were living with HIV in sub-Saharan Africa. The prevalence of HIV infection in this group was 4.0%, compared with 5.0% among those aged 15-49 years. Of the approximately 21 million people in sub-Saharan Africa aged > 15 years that were HIV+, 14.3% were > 50 years old. CONCLUSION: To better reflect the longer survival of people living with HIV and the ageing of the HIV+ population, indicators of the prevalence of HIV infection should be expanded to include people > 49 years of age. Little is known about comorbidity and sexual behaviour among HIV+ older adults or about the biological and cultural factors that increase the risk of transmission. HIV services need to be better targeted to respond to the growing needs of older adults living with HIV.

Joel, Negin; Robert G, Cumming.

363

The method of triple-tube TDCR quench efficiency curve measured for liquid scintillation source radioactive  

International Nuclear Information System (INIS)

The principle and method of measured for liquid scintillation source by triple-tube TDCR method. Using a set of known number radioactive 14C (n-HEXADECANE) liquid scintillation quench series source for verified the aforementioned method. Suggest a method for improving detect efficiency and discounting extrapolation error. Draw up a computer procedure of measurement process. (authors)

364

A critical evaluation of the experimental design of studies of mechanism based enzyme inhibition, with implications for in vitro-in vivo extrapolation.  

Science.gov (United States)

The published literature on mechanism based inhibition (MBI) of CYPs was evaluated with respect to experimental design, methodology and data analysis. Significant variation was apparent in the dilution factor, ratio of preincubation to incubation times and probe substrate concentrations used, and there were some anomalies in the estimation of associated kinetic parameters (k(inact), K(I), r). The impact of the application of inaccurate values of k(inact) and K(I) when extrapolating to the extent of inhibition in vivo is likely to be greatest for those compounds of intermediate inhibitory potency, but this also depends on the fraction of the net clearance of substrate subject to MBI and the pre-systemic and systemic exposure to the inhibitor. For potent inhibitors, the experimental procedure is unlikely to have a material influence on the maximum inhibition. Nevertheless, the bias in the values of the kinetic parameters may influence the time for recovery of enzyme activity following re-synthesis of the enzyme. Careful attention to the design of in vitro experiments to obtain accurate kinetic parameters is necessary for a reliable prediction of different aspects of the in vivo consequences of MBI. The review calls for experimental studies to quantify the impact of study design in studies of MBI, with a view to better harmonisation of protocols. PMID:16611025

Ghanbari, F; Rowland-Yeo, K; Bloomer, J C; Clarke, S E; Lennard, M S; Tucker, G T; Rostami-Hodjegan, A

2006-04-01

365

The evaluation of high-stress creep ductility for 316 stainless steel at 550 deg. C by extrapolation of constitutive equations derived for lower stress levels  

International Nuclear Information System (INIS)

The CDM-based constitutive equations for the creep of 316 Stainless Steel at 550 deg. C are reviewed. During creep tests carried out under these conditions, it has been observed that as time elapses inelastic straining takes place due to time independent plasticity and to creep. It has been recognised that at high stress levels the time dependent plastic strain accumulated during constant load creep tests forms a major part of the inelastic strain and dominates over the creep strain. Hence, due to the plastic strain the true stress level is not constant during the test. The time independent plastic strain has been evaluated using a stress-strain curve obtained at a high strain rate, and the creep strains have been evaluated for the relevant stress history by integration of the constitutive equations. Minimum creep rates and lifetimes have been extrapolated from low stresses to higher stresses using linear stress versus logarithmic plots. In this way, the creep strain-time history, the minimum creep rates, lifetimes and ductilities have been evaluated. In the stress range 325-450 MPa a lower shelf ductility of 1.1% has been found. The model is also shown to predict the isochronous rupture locus determined from multi-axial test data obtained from a range of different sources

366

Thyroid dose assessment for the Chernigov region (Ukraine): estimation based on {sup 131}I thyroid measurements and extrapolation of the results to districts without monitoring  

Energy Technology Data Exchange (ETDEWEB)

Based on the results of {sup 131}I thyroid activity measurements in three districts of the Chernigov region (Ukraine), individual doses were calculated and an approach of the age dependence of the average thyroid exposure was derived. Using the relationships between the thyroid doses and the {sup 137}Cs deposition as well as the location relative to the Chernobyl Nuclear Power plant (NPP), age-dependent average thyroid doses were extrapolated also for those settlements of this region where no monitoring measurements have been carried out. The highest doses were found in the west of the region with the lowest distance to the Chernobyl NPP. In this part, the highest mean of the thyroid dose in a settlement was 3.3 Gy for infants and 0.5 Gy for adults. The collective thyroid dose was 31000 and 27000 person-Gy for children and adults, respectively. Based on this assessment, 140 and 21 excess thyroid cancer cases are predicted for children and adults, respectively. In the years 1989 to 1991, in the whole contaminated territory of the Ukraine 0.4-1.2 cases per 100000 children were observed. Although the absolute numbers are very small, this indicates the possibility of an increase in thyroid cancer morbidity among children. The same trend also seems to be indicated in the Chernigov region. (orig./MG)

Likhtarev, I.A. [Ukrainian Scientific Center of Radiation Medicine, Kiev (Ukraine); Gulko, G.M. [Ukrainian Scientific Center of Radiation Medicine, Kiev (Ukraine); Sobolev, B.G. [Ukrainian Scientific Center of Radiation Medicine, Kiev (Ukraine); Kairo, I.A. [Ukrainian Scientific Center of Radiation Medicine, Kiev (Ukraine); Chepurnoy, N.I. [Ukrainian Scientific Center of Radiation Medicine, Kiev (Ukraine); Proehl, G. [GSF-Forschungszentrum fuer Umwelt und Gesundheit, Inst. fuer Strahlenschutz, Oberschleissheim (Germany); Henrichs, K. [Siemens AG, Muenchen (Germany)

1994-04-01

367

Regression models in the determination of the absorbed dose with extrapolation chamber for ophthalmological applicators; Modelos de regresion en la determinacion de la dosis absorbida con camara de extrapolacion para aplicadores oftalmologicos  

Energy Technology Data Exchange (ETDEWEB)

The absorbed dose for equivalent soft tissue is determined,it is imparted by ophthalmologic applicators, ({sup 90} Sr/{sup 90} Y, 1850 MBq) using an extrapolation chamber of variable electrodes; when estimating the slope of the extrapolation curve using a simple lineal regression model is observed that the dose values are underestimated from 17.7 percent up to a 20.4 percent in relation to the estimate of this dose by means of a regression model polynomial two grade, at the same time are observed an improvement in the standard error for the quadratic model until in 50%. Finally the global uncertainty of the dose is presented, taking into account the reproducibility of the experimental arrangement. As conclusion it can infers that in experimental arrangements where the source is to contact with the extrapolation chamber, it was recommended to substitute the lineal regression model by the quadratic regression model, in the determination of the slope of the extrapolation curve, for more exact and accurate measurements of the absorbed dose. (Author)

Alvarez R, J.T.; Morales P, R

1992-06-15

368

An empirical method to correlate and predict solute distribution in ternary liquid-liquid systems  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a method that combines activity coefficient models with Hand's equation for tie lines. The proposed method calculates solute distribution in liquid-liquid ternary systems. The combination improves the calculated solute distributions using activity coefficient models while Hand's equation gives a good correlation of the experimental tie lines. The method could be used to extrapolate experimental information.

J.M. Zamaro

2002-07-01

369

Effect of albumin on human liver microsomal and recombinant CYP1A2 activities: impact on in vitro-in vivo extrapolation of drug clearance.  

Science.gov (United States)

Long-chain unsaturated fatty acids inhibit several cytochrome P450 and UDP-glucuronosyltransferase (UGT) enzymes involved in drug metabolism, including CYP2C8, CYP2C9, UGT1A9, UGT2B4, and UGT2B7. Bovine serum albumin (BSA) enhances these cytochrome P450 and UGT activities by sequestering fatty acids that are released from membranes, especially with human liver microsomes (HLM) as the enzyme source. Here, we report the effects of BSA on CYP1A2-catalyzed phenacetin (PHEN) O-deethylation and lidocaine (LID) N-deethylation using HLM and Escherichia coli-expressed recombinant human CYP1A2 (rCYP1A2) as the enzyme sources. BSA (2% w/v) reduced (p acid mixture, comprising 3 ?M concentrations each of oleic acid and linoleic acid plus 1.5 ?M arachidonic acid, doubled the K(m) value for PHEN O-deethylation by rCYP1A2. Inhibition was reversed by the addition of BSA. K(i) values for the individual fatty acids ranged from 4.7 to 16.7 ?M. Single-point in vitro-in vivo extrapolation (IV-IVE) based on the human liver microsomal kinetic parameters obtained in the presence, but not absence, of BSA predicted in vivo hepatic clearances of PHEN O-deethylation and LID N-deethylation that were comparable to values reported in humans, although in vivo intrinsic clearances were underpredicted. Prediction of the in vivo clearances of the CYP1A2 substrates observed here represents an improvement on other experimental systems used for IV-IVE. PMID:22331994

Wattanachai, Nitsupa; Tassaneeyakul, Wichittra; Rowland, Andrew; Elliot, David J; Bowalgaha, Kushari; Knights, Kathleen M; Miners, John O

2012-05-01

370

Scale extrapolation for the first wall of fusion reactor DEMO of deuterium recycling parameter in MANET obtained in a plasma simulator of JRC/IAM/ISPRA  

International Nuclear Information System (INIS)

The paper presents the main characteristics of the plasma/implantation/recycling experiment been carried out at the IAM, JRC-Ispra. The modelling aspects for the case of deuterium bombardment in martensitic steel DIN 1.9141 (MANET) are detailed. Once verified that release is surface-limited the surface constants, recombination (K2) and dissociation (K1) constants are determined by fitting the experimental pressure due to the gas desorbed in the measuring chamber. The values obtained for the dissociation constant are: K1=7.10''-6 (mol.Pa''-1.m''-2.s''-1). The recombination constant K2 follows the Arrhenius law:?.K2=2.414* exp(-1571/RT) (m''4.mol''-1.s''-1), R=8.314 J.mol''-1. K''-1 (?:sticking factor). We have obtained quite high reflection coefficients (R>80%) in good agreement with other existing results and with the classical low-energy scattering theory. For temperatures ranging between: 300 and 600 K, ionic fluxes between: 2.10''20??(m''-2 s''-1)?1.10''21 and ion energies for D3 ''+ from 150 to 300 eV the obtained results for K2, K1 and R show a light dispersion. Activation energies for dissociation and recombination are comparable to those obtained from permeation experiments. The design of our experiment allows simple but accurate scale-extrapolations for the tracking of tritium at the First Wall of fusion reactor DEMO. Without taking into consideration other structura into consideration other structural phenomena (erosion. redeposition,...) having synergistic effects, the results obtained would minimise the negative impact of tritium related problems for the design of the First Wall of fusion reactor DEMO. (Author) 6 refs

371

Primary standardization of activity using the coincidence method based on analogue instrumentation  

Energy Technology Data Exchange (ETDEWEB)

Widely implemented at national metrology institutes (NMIs), the coincidence method is a technique to assay a wide variety of radionuclides which decay through two or more types of radiation. Through a survey of the literature, this paper seeks to describe the main aspects of one of the most powerful direct methods available in radionuclide metrology. The basics of coincidence counting and the efficiency extrapolation method are covered. The problem of non-linearities in the extrapolation curve is also considered. The main characteristics of variants to the conventional coincidence instrumentation are presented. (author)

Bobin, Ch. [Laboratoire National Henri Becquerel CEA/Saclay, (LNE-LNHB), 91 - Gif sur Yvette (France)

2007-08-15

372

Primary standardization of activity using the coincidence method based on analogue instrumentation  

International Nuclear Information System (INIS)

Widely implemented at national metrology institutes (NMIs), the coincidence method is a technique to assay a wide variety of radionuclides which decay through two or more types of radiation. Through a survey of the literature, this paper seeks to describe the main aspects of one of the most powerful direct methods available in radionuclide metrology. The basics of coincidence counting and the efficiency extrapolation method are covered. The problem of non-linearities in the extrapolation curve is also considered. The main characteristics of variants to the conventional coincidence instrumentation are presented. (author)

373

ELMs and disruptions in ITER: Expected energy fluxes on plasma-facing components from multi-machine experimental extrapolations and consequences for ITER operation  

International Nuclear Information System (INIS)

Operation of ITER in high fusion gain regimes comes associated with plasma conditions in which Plasma Facing Components (PFCs) can be subject to large energy fluxes by ELMs and disruptions. These loads can contribute significantly to the overall erosion rate and lifetime of these components. Significant progress in the characterisation of the ELM and disruption transient loads in divertor tokamak experiments has taken place in the last few years. The measurements obtained have provided a physics-based framework on which the expected transient energy loads on ITER PFCs can be estimated. The expected ELM power fluxes depend on the mechanism dominating the energy loss from the plasma during ELMs: conduction and convection. Convective ELMs are associated with small normalised ELM energy losses, which would be compatible with the required lifetime of the ITER PFCs, but are obtained in conditions which are not compatible (pedestal collisionality or normalised energy confinement) with the ITER reference scenario. Studies of the energy balance and power fluxes during disruptions have shown that the thermal energy of the plasma at the thermal quench is a factor of 2-4 lower than that of the full performance plasma for most plasma conditions. Most of the plasma thermal energy during disruptions is deposited on PFCs by conduction/convection during the thermal quench, onto an area which is a factor of 5-10 larger than for normal plasma operation. On the basis of these results, theration. On the basis of these results, the expected fluxes on the ITER PFCs during transients are : (1) Divertor target. Type I ELM energy fluxes: 0.5-4 MJ/m2 in timescales of 300-600 microseconds, Thermal quench energy fluxes of 2-13 MJ/m2 in timescales of 1-3 ms. (2) Main wall. Type I ELM energy fluxes: 0.5-2 MJ/m2 in timescales of 300-600 microseconds. Thermal quench energy fluxes of 0.5-5 MJ/m2 in timescales of 1-3 ms. Mitigated disruption radiative loads of 0.1-2 MJ/m2 in timescales of 0.2-1.0 ms. The physics models used to perform the extrapolations from present devices to ITER and the results of the experimental and modelling studies carried out to determine the associated erosion of the divertor and main chamber PFCs in ITER and the implications for the plasma discharge and the operation of the device for transient loads in these ranges will be discussed. (author)

374

Production and characterization of TI/PbO2 electrodes by a thermal-electrochemical method  

Directory of Open Access Journals (Sweden)

Full Text Available Looking for electrodes with a high overpotential for the oxygen evolution reaction (OER, useful for the oxidation of organic pollutants, Ti/PbO2 electrodes were prepared by a thermal-electrochemical method and their performance was compared with that of electrodeposited electrodes. The open-circuit potential for these electrodes in 0.5 mol L-1 H2SO4 presented quite stable similar values. X-ray diffraction analyses showed the thermal-electrochemical oxide to be a mixture of ort-PbO, tetr-PbO and ort-PbO2. On the other hand, the electrodes obtained by electrodeposition were in the tetr-PbO2 form. Analyses by scanning electron microscopy showed that the basic morphology of the thermal-electrochemical PbO2 is determined in the thermal step, being quite distinct from that of the electrodeposited electrodes. Polarization curves in 0.5 mol L-1 H2SO4 showed that in the case of the thermal-electrochemical PbO2 electrodes the OER was shifted to more positive potentials. However, the values of the Tafel slopes, quite high, indicate that passivating films were possibly formed on the Ti substrates, which could eventually explain the somewhat low current values for OER.

Laurindo Edison A.

2000-01-01

375

Corporate Governance in Post-Socialist Countries - Theoretical Dilemmas, Peculiarities, Research Opportunities / Külliki Tafel, Erik Terk, Alari Purju  

Index Scriptorium Estoniae

Äriühingute valitsemine postsotsialistlikes riikides - teoreetilised dilemmad, eripärad, uurimisvõimalused. Skeemid: Internal and external relations of corporate governanace; The changing context of corporate governance

Tafel, Külliki

2006-01-01

376

Abnormalities Of Larval Male Gonads Of SPODOPTERA LITTORALIS (BOISD.) After Exposure To GAMMA Radiation In Combined With Tafel Leaves Extract  

International Nuclear Information System (INIS)

The effect of sub-sterilizing dose of gamma radiation (125 Gy) alone or in joint with different concentrations of tafla leaves extract Nerium oleander on the histology and histochemistry of the larval male reproductive system were studied. The treatment caused histopathological changes in the testes including necrosis of spermatocytes, retardation of sperm maturation, bursting of sperm bundles and the vacuolated area resulting from depletion of spermatogonia that increased in size.Histochemical studies showed that protein contents and RNA were increased while DNA content was decreased in male gonads.

377

Kolm linna ja kolm lähenemist loovusele ja kultuuri arendamisele : Tartu, Turu ja Bergen : loomemajandus / Külliki Tafel, Erik Terk  

Index Scriptorium Estoniae

Tartu, Turu ja Bergen koostasid Põhjamaade Innovatsioonikeskuse projekti "Nordic Model for Creative Industries Development Center" raames oma linnade loomemajanduse arendamise dokumendi. Võrreldakse valminud dokumente

Tafel, Külliki

2008-01-01

378

Lits fluidisés pour l'industrie chimique. Extrapolation et amélioration des catalyseurs. Première partie : Etudes et modèles. Enseignements issus des pilotes Fluidized Beds in Chemical Industry. Scale Up and Catalysts Improvement. First Part: Studies, Models, Learning from Pilot Plants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Les unités de production en lits fluidisés catalytiques sont apparues vers 1942 dans l'industrie pétrolière et vers 1960 dans l'industrie chimique. On se limitera ici au problème de l'extrapolation des lits fluidisés catalytiques pour l'industrie chimique, qui exigent de très hautes performances (> 99 % de conversion). Leur mise au point a, dans le passé, nécessité l'exploitation sur des sites industriels de coûteux pilotes de 0,5 m de diamètre et de plus de 10 m de hauteur. Nous ...

Botton R.

2006-01-01

379

Characterization of an extrapolation chamber and radiochromic films for verifying the metrological coherence among beta radiation fields; Caracterizacao de uma camara de extrapolacao e filmes radiocromicos para verificacao da coerencia metrologica entre campos padroes de radiacao beta  

Energy Technology Data Exchange (ETDEWEB)

The metrological coherence among standard systems is a requirement for assuring the reliability of dosimetric quantities measurements in ionizing radiation field. Scientific and technologic improvements happened in beta radiation metrology with the installment of the new beta secondary standard BSS2 in Brazil and with the adoption of the internationally recommended beta reference radiations. The Dosimeter Calibration Laboratory of the Development Center for Nuclear Technology (LCD/CDTN), in Belo Horizonte, implemented the BSS2 and methodologies are investigated for characterizing the beta radiation fields by determining the field homogeneity, the accuracy and uncertainties in the absorbed dose in air measurements. In this work, a methodology to be used for verifying the metrological coherence among beta radiation fields in standard systems was investigated; an extrapolation chamber and radiochromic films were used and measurements were done in terms of absorbed dose in air. The reliability of both the extrapolation chamber and the radiochromic film was confirmed and their calibrations were done in the LCD/CDTN in {sup 90}Sr/{sup 90}Y, {sup 85}Kr and {sup 147}Pm beta radiation fields. The angular coefficients of the extrapolation curves were determined with the chamber; the field mapping and homogeneity were obtained from dose profiles and isodose with the radiochromic films. A preliminary comparison between the LCD/CDTN and the Instrument Calibration Laboratory of the Nuclear and Energy Research Institute / Sao Paulo (LCI/IPEN) was carried out. Results with the extrapolation chamber measurements showed in terms of absorbed dose in air rates showed differences between both laboratories up to de -I % e 3%, for {sup 90}Sr/{sup 90}Y, {sup 85}Kr and {sup 147}Pm beta radiation fields, respectively. Results with the EBT radiochromic films for 0.1, 0.3 and 0.15 Gy absorbed dose in air, for the same beta radiation fields, showed differences up to 3%, -9% and -53%. The beta radiation field mappings with radiochromic films in both BSS2 showed that some of them were not geometrically aligned. (author)

Castillo, Jhonny Antonio Benavente

2011-07-01

380

An Individual-based Model for Extrapolating Standard Toxicity Test Data into Population-level Adverse Outcomes in the Fathead Minnow  

Science.gov (United States)

While environmental toxicity testing typically focuses on organism-level endpoints such as mortality, growth, and reproduction, risk assessment guidelines specify protection goals at the level of the population and above. One method of linking these different levels of biological...

 
 
 
 
381

Copper corrosion inhibition in O2-saturated H2SO4 solutions  

International Nuclear Information System (INIS)

Corrosion inhibition of copper in O2-saturated 0.50 M H2SO4 solutions by four selected amino acids, namely glycine (Gly), alanine (Ala), valine (Val), or tyrosine (Tyr), was studied using Tafel polarization, linear polarization, impedance, and electrochemical frequency modulation (EFM) at 30 deg. C. Protection efficiencies of almost 98% and 91% were obtained with 50 mM Tyr and Gly, respectively. On the other hand, Ala and Val reached only about 75%. Corrosion rates determined by the Tafel extrapolation method were in good agreement with those obtained by EFM and an independent chemical (i.e., non-electrochemical) method. The chemical method of confirmation of the corrosion rates involved determination of the dissolved Cu2+, using ICP-AES (inductively coupled plasma atomic emission spectrometry) method of chemical analysis. Nyquist plots exhibited a high frequency depressed semicircle followed by a straight line portion (Warburg diffusion tail) in the low-frequency region. The impedance data were interpreted according to two suitable equivalent circuits. The kinetics of dissolved O2 reduction and hydrogen evolution reactions on copper surface were also studied in O2-saturated 0.50 M H2SO4 solutions using polarization measurements combined with the rotating disc electrode (RDE). The Koutecky-Levich plot indicated that the dissolved O2 reduction at the copper electrode was ub> reduction at the copper electrode was an apparent 4-electron process.

382

Report on the uncertainty methods study  

International Nuclear Information System (INIS)

The Uncertainty Methods Study (UMS) Group, following a mandate from CSNI, has compared five methods for calculating the uncertainty in the predictions of advanced 'best estimate' thermal-hydraulic codes: the Pisa method (based on extrapolation from integral experiments) and four methods identifying and combining input uncertainties. Three of these, the GRS, IPSN and ENUSA methods, use subjective probability distributions, and one, the AEAT method, performs a bounding analysis. Each method has been used to calculate the uncertainty in specified parameters for the LSTF SB-CL-18 5% cold leg small break LOCA experiment in the ROSA-IV Large Scale Test Facility (LSTF). The uncertainty analysis was conducted essentially blind and the participants did not use experimental measurements from the test as input apart from initial and boundary conditions. Participants calculated uncertainty ranges for experimental parameters including pressurizer pressure, primary circuit inventory and clad temperature (at a specified position) as functions of time

383

Splitting methods for Levitron Problems  

CERN Document Server

In this paper we describe splitting methods for solving Levitron, which is motivated to simulate magnetostatic traps of neutral atoms or ion traps. The idea is to levitate a magnetic spinning top in the air repelled by a base magnet. The main problem is the stability of the reduced Hamiltonian, while it is not defined at the relative equilibrium. Here it is important to derive stable numerical schemes with high accuracy. For the numerical studies, we propose novel splitting schemes and analyze their behavior. We deal with a Verlet integrator and improve its accuracy with iterative and extrapolation ideas. Such a Hamiltonian splitting method, can be seen as geometric integrator and saves computational time while decoupling the full equation system. Experiments based on the Levitron model are discussed.

Geiser, Juergen

2012-01-01

384

Generalized 4{pi}(LS){beta}-{gamma} tracer method for standardization of pure beta emitters  

Energy Technology Data Exchange (ETDEWEB)

The basic mathematical relationships, as well as experimental results, are presented for a generalized tracer method, with a multiparameter coincidence and anti-coincidence system, for absolute activity measurements of pure beta-emitters. A liquid scintillation counter, with two photomultipliers working in coincidence, was used for beta-particle detection and two scintillation counters with NaI(Tl) crystals for gamma-photon detection. A double extrapolation procedure has been applied: first, extrapolation as a function of tracer counting efficiency, and second, extrapolation as a function of emitter to tracer concentration ratio in the mixed radioactive solution. It should be emphasized that application of the second extrapolation procedure minimizes the counting uncertainty given by the first procedure. The experimental results are illustrated by {sup 63}Ni and {sup 147}Pm activity measurements with the same tracer, {sup 60}Co. The uncertainties obtained were within a limit of 1% for a 0.99 confidence level. The radioactive solutions in question ({sup 63}Ni, {sup 147}Pm) were measured afterwards by the TDCR method (triple to double coincidence ratio) and the results compared. Good agreement (within the uncertainties of both methods) was obtained. (orig.).

Chylinski, A. [Radioisotope Centre, Swierk (Poland); Radoszewski, T. [Radioisotope Centre, Swierk (Poland)

1996-02-01

385

Generalized 4?(LS)?—? tracer method for standardization of pure beta emitters  

Science.gov (United States)

The basic mathematical relationships, as well as experimental results, are presented for a generalized tracer method, with a multiparameter coincidence and anti-coincidence system, for absolute activity measurements of pure beta-emitters. A liquid scintillation counter, with two photomultipliers working in coincidence, was used for beta-particle detection and two scintillation counters with NaI(Tl) crystals for gamma-photon detection. A double extrapolation procedure has been applied: first, extrapolation as a function of tracer counting efficiency, and second, extrapolation as a function of emitter to tracer concentration ratio in the mixed radioactive solution. It should be emphasized that application of the second extrapolation procedure minimizes the counting uncertainty given by the first procedure. The experimental results are illustrated by 63Ni and 147Pm activity measurements with the same tracer, 60Co. The uncertainties obtained were within a limit of 1% for a 0.99 confidence level. The radioactive solutions in question ( 63Ni, 147Pm) were measured afterwards by the TDCR method (triple to double coincidence ratio) and the results compared. Good agreement (within the uncertainties of both methods) was obtained.

Chyliñski, A.; Radoszewski, T.

1996-02-01

386

An improved Compton scattering method for determination of concentration of solutions.  

Science.gov (United States)

An improved Compton scattering method for determination of concentration of low-Z solutions is presented. The Monte Carlo (MC) numerical simulation of the scattering phenomena is done using the MCNP code. A unique non-linear extrapolation method is followed in correcting the scattered intensity for self-absorption and multiple scattering. The density ratios obtained using non linear extrapolated scattered intensity values are free from self-absorption and multiple scattering and agree well with the standard ones within experimental errors. The sensitivity study of transmission and scattering methods for determination of concentration of solutions having closer attenuation parameters at 661.6 keV is carried out to predict the range of effectiveness and suitability of these methods. The slopes (sensitivity/unit concentration) of the curves obtained from scattering method are higher by a factor of 1.26 compared to those of the transmission method in the measured range of concentrations. PMID:22871448

Priyada, P; Ramar, R; Shivaramu

2012-10-01

387

Contribution to the extrapolation from short time to long time wear behaviour of cylinder liners and faces and flanks of piston rings  

International Nuclear Information System (INIS)

It is a problem frequently encountered in experiments with combustion engines that conclusions on the wear behaviour after long periods of running should be drawn from the data of wear measurements over a short running interval only. For diesel engines and the case of continuous wear measurements on critical engine components over a short period of time this problem was treated with mathematical statistics known in literature. When the system developed in this work is applied to the results of a short time experiment, it is possible to calculate maximum wear niveaus for calculated percentages of engine components identical to those used in this single experiment. A dependance of the fracture of piston rings on piston ring flank wear acceleration is discussed, and a method for life time predictions with respect to the fracture of piston rings in diesel engines is given. With several practical examples the suitability of the methods presented ist demonstrated for work engine development. (orig.)

388

An improved Compton scattering method for determination of concentration of solutions  

International Nuclear Information System (INIS)

An improved Compton scattering method for determination of concentration of low-Z solutions is presented. The Monte Carlo (MC) numerical simulation of the scattering phenomena is done using the MCNP code. A unique non-linear extrapolation method is followed in correcting the scattered intensity for self-absorption and multiple scattering. The density ratios obtained using non linear extrapolated scattered intensity values are free from self-absorption and multiple scattering and agree well with the standard ones within experimental errors. The sensitivity study of transmission and scattering methods for determination of concentration of solutions having closer attenuation parameters at 661.6 keV is carried out to predict the range of effectiveness and suitability of these methods. The slopes (sensitivity/unit concentration) of the curves obtained from scattering method are higher by a factor of 1.26 compared to those of the transmission method in the measured range of concentrations. - Highlights: ? Improved Compton scattering method for determination of concentration of solutions. ? The Monte Carlo (MC) numerical simulation of the scattering phenomena is done. ? A unique extrapolation method of correcting self-absorption and multiple scattering. ? The sensitivity of the scattering method is higher compared to the transmission method.

389

Research of method for activity measurement of neutron-activation-foil  

International Nuclear Information System (INIS)

This paper puts forward a new method measuring the activity of neutron-activation-foil using 4??-? coincidence equipment without making thin film source. By changing the voltage of photomultiplier tube, keeping the same efficiency of the ? detector in detection of ? photon and X ray of K shell, we can obtain the activity of neutron-activation-foil, without using efficiency extrapolation method. Theory analysis indicates that the method is feasible. (authors)

390

On the equivalence of LIST and DIIS methods for convergence acceleration  

CERN Document Server

Self-consistent field extrapolation methods play a pivotal role in quantum chemistry and electronic structure theory. We here demonstrate the mathematical equivalence between the recently proposed family of LIST methods [J. Chem. Phys. 134, 241103 (2011); J. Chem. Theory Comput. 7, 3045 (2011)] with Pulay's DIIS [Chem. Phys. Lett. 73, 393 (1980)]. Our results also explain the differences in performance among the various LIST methods.

Garza, Alejandro J

2014-01-01

391

A comparison of methods of determining the 100 percent survival of preserved red cells  

International Nuclear Information System (INIS)

Studies were done to compare three methods to determine the 100 percent survival value from which to estimate the 24-hour posttransfusion survival of preserved red cells. The following methods using small aliquots of 51Cr-labeled autologous preserved red cells were evaluated: First, the 125I-albumin method, which is an indirect measurement of the recipient's red cell volume derived from the plasma volume measured using 125I-labeled albumin and the total body hematocrit. Second, the body surface area method (BSA) in which the recipient's red cell volume is derived from a body surface area nomogram. Third, an extrapolation method, which extrapolates to zero time the radioactivity associated with the red cells in the recipient's circulation from 10 to 20 or 15 to 30 minutes after transfusion. The three methods gave similar results in all studies in which less than 20 percent of the transfused red cells were nonviable (24-hour posttransfusion survival values of between 80-100%), but not when more than 20 percent of the red cells were nonviable. When 21 to 35 percent of the transfused red cells were nonviable (24-hour posttransfusion survivals of 65 to 79%), values with the 125I-albumin method and the body surface area method were about 5 percent lower (p less than 0.001) than values with the extrapolation method. When greater than 35 percent of the red cells were nonviable (24-hour posttransfusion survival values of less than 65ransfusion survival values of less than 65%), values with the 125I-albumin method and the body surface area method were about 10 percent lower (p less than 0.001) than those obtained by the extrapolation method

392

Corrosion behavior of aluminum 6061 alloy joined by friction stir welding and gas tungsten arc welding methods  

International Nuclear Information System (INIS)

Highlights: ? FSW demonstrated higher corrosion resistance than GTAW of 6061 Al alloy. ? FSW and GTAW both demonstrated poorer corrosion behavior than the base metal. ? FSW produced ?1–2 ?m equiaxed grains in joint region and ?150 ?m in base metal. ? GTAW resulted in semi-cast dendritic structure. ? T6 heat treatment improved corrosion resistance of both FSW and GTAW joints. -- Abstract: Wrought aluminum sheets with thickness of 13 mm were square butt-welded by friction stir welding (FSW) and gas tungsten arc welding (GTAW) methods. Corrosion behavior of the welding zone was probed by Tafel polarization curve. Optical metallography (OM) and scanning electron microscopy together with energy dispersive spectroscopy (SEM-EDS) were used to determine morphology and semi-quantitative analysis of the welded zone. FSW resulted in equiaxed grains of about 1–2 ?m, while GTAW caused dendritic structure of the welded region. Resistance to corrosion was greater for the FSW grains than the GTAW structure. In both cases, susceptibility to corrosion attack was greater in the welded region than the base metal section. T6 heat treatment resulted in shifting of the corrosion potential towards bigger positive values. This effect was stronger in the welded regions than the base metal section.

393

Alternative curved-boundary treatment for the lattice Boltzmann method and its application in simulation of flow and potential fields.  

Science.gov (United States)

Since the lattice Boltzmann method originally carries out the simulations on the regular Cartesian lattices, curved boundaries are often approximated as a series of stair steps. The most commonly employed technique for resolving curved-boundary problems is extrapolating or interpolating macroscopic properties of boundary nodes. Previous investigations have indicated that using more than one equation for extrapolation or interpolation in boundary conditions potentially causes abrupt changes in particle distributions. Therefore, a curved-boundary treatment is introduced to improve computational accuracy of the conventional stair-shaped approximation used in lattice Boltzmann simulations by using a unified equation for extrapolation of macroscopic variables. This boundary condition is not limited to fluid flow and can be extended to potential fields. The proposed treatment is tested against several well-established problems and the solutions order of accuracy is evaluated. Numerical results show that the present treatment is of second-order accuracy and has reliable stability characteristics. PMID:24580362

Mohammadipoor, O R; Niazmand, H; Mirbozorgi, S A

2014-01-01

394

Molecular polarizability of organic molecules and their complexes. Communication LIV. Molar volumes of polyaryl organoelement compounds in solutions, extrapolated to infinite dilution, and steric structure of the molecules  

International Nuclear Information System (INIS)

Molar volumes in various solvents were determined for organic derivatives of silicon, phosphorus, arsenic, sulfur, and tellurium, containing aryl nuclei capable to internal rotation about single bonds between them and bridging groups. Additive analysis of the molar volumes of these compounds showed that the aryl nuclei are acoplanar with respect to the bridging groups. Most probable is a conrotatory mutual orientation of the aromatic rings. Molar volumes were also determined for a series of compounds with two bridging groups, which can serve as models of an extreme case of mutual proximity of aryl ring planes in diaryl systems with one bridging group. A possibility for considerably simplifying the methods for determination of dipole moments and Kerr constants for compounds whose molar volumes can be calculated by our developed additive scheme is demonstrated

395

Comparative study among calibration methods of clinical applicators of beta radiation  

International Nuclear Information System (INIS)

90Sr+90Y clinical applicators are instruments used in brachytherapy procedures and they have to be periodically calibrated, according to international standards and recommendations. In this work, four calibration methods of dermatological and ophthalmic applica