1

Digital Repository Infrastructure Vision for European Research (DRIVER)

Tafel back extrapolation of the cathodic reaction was used to interpret polarization data obtained for titanium alloyed with small amounts of ruthenium and palladium in concentrated hydrochloric acid. It was found that the ruthenium and palladium stimulated the cathodic reaction, but that the anodic...

Sandenbergh, R.F.; Van der Lingen, E.

2

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

1984-01-01

3

Method for restoring and extrapolating seismic traces

Energy Technology Data Exchange (ETDEWEB)

This paper discusses a method for enhancing a x-t domain seismic record. It comprises identifying a null seismic trace of restoration; selecting a group of traces surrounding the identified null seismic trace to be restored on the x-t domain seismic record; transforming the group of selected traces into the f-x domain by the application of a fast Fourier transform; selecting a series of complex numbers corresponding to the selected traces for each frequency component; estimating a set of autoregressive coefficients from the series of complex numbers; estimating a complex number for the missing number associated with the identified null trace from the series of complex numbers and autoregressive coefficients on either side of the missing number; repeating the last three steps for frequencies in the f-x domain and applying an inverse fast Fourier transform to the estimated complex numbers for the frequencies to produce restored seismic data for identified seismic traces on the x-t domain street record.

Laster, S.J.; Meek, R.A.; Shirley, T.E.

1990-08-28

4

Implicit extrapolation methods for multilevel finite element computations

Energy Technology Data Exchange (ETDEWEB)

The finite element package FEMGP has been developed to solve elliptic and parabolic problems arising in the computation of magnetic and thermomechanical fields. FEMGP implements various methods for the construction of hierarchical finite element meshes, a variety of efficient multilevel solvers, including multigrid and preconditioned conjugate gradient iterations, as well as pre- and post-processing software. Within FEMGP, multigrid {tau}-extrapolation can be employed to improve the finite element solution iteratively to higher order. This algorithm is based on an implicit extrapolation, so that the algorithm differs from a regular multigrid algorithm only by a slightly modified computation of the residuals on the finest mesh. Another advantage of this technique is, that in contrast to explicit extrapolation methods, it does not rely on the existence of global error expansions, and therefore neither requires uniform meshes nor global regularity assumptions. In the paper the authors will analyse the {tau}-extrapolation algorithm and present experimental results in the context of the FEMGP package. Furthermore, the {tau}-extrapolation results will be compared to higher order finite element solutions.

Jung, M.; Ruede, U. [Technische Universitaet Chemnitz-Zwickau (Germany)

1994-12-31

5

Assessment of Load Extrapolation Methods for Wind Turbines

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the present paper, methods for statistical load extrapolation of wind-turbine response are studied using a stationary Gaussian process model, which has approximately the same spectral properties as the response for the out-of-plane bending moment of a windturbine blade. For a Gaussian process, an...

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard; Veldkamp, Dick

6

Methods for Extrapolating Risk Equations Beyond Their Valid Intervals

Methods for Extrapolating Risk Equations Beyond Their Valid Intervals Griffin Weber, S.M., Nananda F. Col, M.D., M.P.P., M.P.H., F.A.C.P. Decision Systems Group, Division of Women’s Health, Harvard Medical School, Boston, MA Purpose: Decision models

7

Assessment of Load Extrapolation Methods for Wind Turbines

DEFF Research Database (Denmark)

In the present paper methods for statistical load extrapolation of wind turbine response are studied using a stationary Gaussian process model which has approximately the same spectral properties as the response for the flap bending moment of a wind turbine blade. For a Gaussian process an approximate analytical solution for the distribution of the peaks is given by Rice. In the present paper three different methods for statistical load extrapolation are compared with the analytical solution for one mean wind speed. The methods considered are global maxima, block maxima and the peak over threshold method with two different threshold values. The comparisons show that the goodness of fit for the local distribution has a significant influence on the results, but the peak over threshold method with a threshold value on the mean plus 1.4 standard deviations generally gives the best results. By considering Gaussian processes for twelve mean wind speeds the ‘fitting before aggregation’ and ‘aggregation before fitting’ approaches are studied. The results show that the ‘fitting before aggregation’ approach gives the best results.

Toft, Henrik Stensgaard; SØrensen, John Dalsgaard

2010-01-01

8

Comparison of methods for extrapolating breaking creep results

International Nuclear Information System (INIS)

Among all the methods of extrapolation, the following have been selected: - parametric methods (Larson-Miller, Dorn, Manson-Haferd); - digital and parametric method (minimum commitment); - digital method (finite differences); - descriptive method (Givar). The Larson-Miller, Dorn and Manson-Haferd methods are commonly used for analyzing the breaking creep results of materials for which the master curves can be described simply. The other methods have been developed in order to analyze the breaking creep results of materials where the structural changes over time modify the creep behaviour. In each case the assessment of the parameters is achieved by the least squares method. These methods were compared with each other on two steels, namely: Z6 CND 17-12 (316) and Z4 CND 35-20 (800 alloy). The various analyses performed show that (a) the predictions made as from the different methods are in good agreement between each other when there is a sufficient number of experimental values and (b) the predictions of the breaking times in the case of the 800 alloy differ from one method to the next. This result is due to the limited sampling data and to the complex behaviour of this alloy, the properties of which change with ageing.

1980-06-19

9

Type-insensitive ODE codes based on extrapolation methods

Energy Technology Data Exchange (ETDEWEB)

For a long time extrapolation of the (explicit) midpoint rule has been a popular way to solve non-stiff initial value problems for systems of ordinary differential equations (ODEs). In the last few years Bader and Deuflhard have been studying the theory and practice of extrapolation of a semi-implicit midpoint rule for the solution of stiff problems. They have developed an effective code, METAN1, which is the object of attention in this paper.

Shampine, L.F.

1982-06-01

10

Calculation of extrapolation curves in the 4??-? coincidence method

International Nuclear Information System (INIS)

A program has been realised to calculate theoretically the beta, gamma, and coincidence efficiencies and the extrapolated activity value of a given radionuclide which are obtained by 4??-? coincidence measurements, from the nuclear decay data and hypothetical detection efficiency values. It is used for studying more easily, especially in the case of complex decay schemes, the influence of the parameters involved. It can calculate a correction factor for obtaining the true activity value under experimental conditions. Some examples are presented; 133Ba, 51Cr, 195Au and 201Tl. (author)

1987-01-01

11

International Nuclear Information System (INIS)

The activity of electron capture radionuclides is usually determined by 4?(proportional counter, PC)-? coincidence counting. The corrections necessary for the final activity value calculation are obtained by an extrapolation method. Variation of the PC detection efficiency can be achieved through different methods, e.g. by changing the self-absorption of the source using absorbing foils or by adding carriers. Another possibility is a 'wet' extrapolation method, which utilises an absorption change during the drying of a water droplet added onto the source surface. In this paper, slopes of extrapolation curves and resulting activity values obtained by different methods are compared for several radionuclides (54Mn, 139Ce, 88Y, 57Co). In some cases a digital coincidence system was used for the analysis of measured data. The 'wet' extrapolation, due to its very simple procedure, seems to be convenient for routine measurement and its accuracy is similar to the other methods.

2008-01-01

12

UK PubMed Central (United Kingdom)

BACKGROUND: The first issue of this series proposed extrapolation chart with conventional reference range and suggested comparison of results with other methods. AIM: This work sets out to compare interpretative results from the extrapolation method with those from a digital viscometer method. MATERIALS AND METHODS: Five cases in our archived clinical pathology database that were specifically tested for whole blood viscosity by the digital method, and had results for haematocrit and serum proteins were pooled. The values of haematocrit and serum proteins were used to derive extrapolated values. The interpretative results of the extrapolation method were compared with those of digital viscometer-based clinical reports. Non-Newtonian fluids such as whole blood have different viscosities at different shear rates. Comparative statement can only be based on interpreted outcome. RESULTS: Two-fifth absolute concordance and one-fifth discordance is observed between extrapolation and viscometer-based clinical reports. The discordance is a case of hyperviscosity in the presence of neither hyperproteinaemia nor polycythemia. CONCLUSION: The extrapolation method may underestimate whole blood viscosity in some patients when compared with digital viscometer, which in turn may suggest hyperviscosity that cannot be explained by hyperproteinaemia or polycythemia concepts. The impact of oxidative stress is highlighted.

Nwose EU; Richards RS

2011-07-01

13

Extrapolation of Extreme and Fatigue Loads Using Probabilistic Methods

Energy Technology Data Exchange (ETDEWEB)

Probabilistic methods were used to determine the long-term extreme and fatigue loads of two different 1.5 MW wind turbine designs. Over the past decade, probabilistic methods for wind turbine design have acquired increasing levels of interest in both the research and industrial community. This interest has largely been driven by the desire to replace outdated empirical-based design models with more physically relevant models that can be accurately applied to the next generation of wind turbine designs. This study further extends previous works through further examination of moment-based probability methods, as well as the effects of using a joint distribution of mean wind speed and turbulence level, and the statistical uncertainty of moment-based methods, introducing refinements such as compensating for non-zero cyclic midpoints in fatigue calculations, application of a threshold technique and full integration of all probable operating conditions.

Moriarty, P. J.; Holley, W. E.; Butterfield, S. P.

2004-11-01

14

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

2000-01-01

15

A least square extrapolation method for improving solution accuracy of PDE computations

International Nuclear Information System (INIS)

[en] Richardson extrapolation (RE) is based on a very simple and elegant mathematical idea that has been successful in several areas of numerical analysis such as quadrature or time integration of ODEs. In theory, RE can be used also on PDE approximations when the convergence order of a discrete solution is clearly known. But in practice, the order of a numerical method often depends on space location and is not accurately satisfied on different levels of grids used in the extrapolation formula. We propose in this paper a more robust and numerically efficient method based on the idea of finding automatically the order of a method as the solution of a least square minimization problem on the residual. We introduce a two-level and three-level least square extrapolation method that works on nonmatching embedded grid solutions via spline interpolation. Our least square extrapolation method is a post-processing of data produced by existing PDE codes, that is easy to implement and can be a better tool than RE for code verification. It can be also used to make a cascade of computation more numerically efficient. We can establish a consistent linear combination of coarser grid solutions to produce a better approximation of the PDE solution at a much lower cost than direct computation on a finer grid. To illustrate the performance of the method, examples including two-dimensional turning point problem with sharp transition layer and the Navier-Stokes flow inside a lid-driven cavity are adopted

2003-03-20

16

New method for the extrapolation of finite-size data to infinite volume

We present a simple and powerful method for extrapolating finite-volume Monte Carlo data to infinite volume, based on finite-size-scaling theory. We discuss carefully its systematic and statistical errors, and we illustrate it using three examples: the two-dimensional three-state Potts antiferromagnet on the square lattice, and the two-dimensional O(3) and O(\\infty) \\sigma-models. In favorable cases it is possible to obtain reliable extrapolations (errors of a few percent) even when the correlation length is 1000 times larger than the lattice.

Caracciolo, Sergio; Ferreira, S J; Pelissetto, A; Sokal, A D; Caracciolo, Sergio; Edwards, Robert G; Ferreira, Sabino J; Pelissetto, Andrea; Sokal, Alan D

1994-01-01

17

Study on Two Methods for Nonlinear Force-Free Extrapolation Based on Semi-Analytical Field

In this paper, two semi-analytical solutions of force-free fields (Low and Lou, Astrophys. J. 352, 343, 1990) have been used to test two nonlinear force-free extrapolation methods. One is the boundary integral equation (BIE) method developed by Yan and Sakurai ( Solar Phys. 195, 89, 2000), and the other is the approximate vertical integration (AVI) method developed by Song et al. ( Astrophys. J. 649, 1084, 2006). Some improvements have been made to the AVI method to avoid the singular points in the process of calculation. It is found that the correlation coefficients between the first semi-analytical field and extrapolated field using the BIE method, and also that obtained by the improved AVI method, are greater than 90% below a height 10 of the 64×64 lower boundary. For the second semi-analytical field, these correlation coefficients are greater than 80% below the same relative height. Although differences between the semi-analytical solutions and the extrapolated fields exist for both the BIE and AVI methods, these two methods can give reliable results for heights of about 15% of the extent of the lower boundary.

Liu, S.; Zhang, H. Q.; Su, J. T.; Song, M. T.

2011-03-01

18

Numerical solutions of RLW equation using Galerkin method with extrapolation techniques

In this paper, we present a new Galerkin method for the regularized long wave (RLW) equation. Based on the Galerkin method using linear finite elements, the extrapolation technique is proposed to increase the order of the time discretization accuracy to O((), giving O((+h2) overall, which is quite efficient to solve the one-dimensional RLW. A stability analysis based on Von Neumann theory is performed. Propagation of solitary waves, interaction of two solitary waves and undular bores are simulated using the proposed method to validate the method which is found to be accurate and efficient.

Mei, Liquan; Chen, Yaping

2012-08-01

19

International Nuclear Information System (INIS)

The efficiency extrapolation method was improved by establishing ''linearity conditions'' for the discrimination on the gamma channel of the coincidence equipment. These conditions were proved to eliminate the systematic error of the method. A control procedure for the fulfilment of linearity conditions and estimation of residual systematic error was given. For law-energy gamma transitions an ''equivalent scheme principle'' was established, which allow for a correct application of the method. Solutions of Cs-134, Co-57, Ba-133 and Zn-65 were standardized with an ''effective standard deviation'' of 0.3-0.7 per cent. For Zn-65 ''special linearity conditions'' were applied. (author).

1976-01-01

20

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.

2010-01-01

21

Anodic Tafel behaviour of mild steel in presence of inhibitors

Energy Technology Data Exchange (ETDEWEB)

The kinetics of mild steel dissolution in 1.0 N H{sub 2}SO{sub 4} and 1.0 N HCI were studied by steady-state anodic vs potential measurements in presence of varying concentrations of thiourea and thiosemicarbazide. An anodic Tafel slope of 38-40 mV/decade was observed in both acids in accordance with the Bockris model. The anodic Tafel slope increases regularly with increasing the inhibitor concentration. A mechanism is proposed - after Kelly - to explain this effect semiquantitatively. A surface complex is assumed to be formed between the adsorbed inhibitor and the dissolution intermediates. A change of the rds for ion dissolution in presence of the inhibitor, is suggested. (orig.).

Khalil, M.W. (Cairo Univ., Giza (Egypt). Dept. of Chemistry)

1992-03-01

22

Kinetics of polypyrrole electrogeneration on Pt through Tafel slopes

Energy Technology Data Exchange (ETDEWEB)

A study of the Tafel slopes and the subsequent reaction orders, as a function of monomer and electrolyte concentrations, in different electrolytic medias, for polypyrrole electrogeneration, is presented. The evolution of the Tafel representations is similar in all the analyzed systems (acetonitrile, water and acetonitrile +2% of water). Two straight lines with a net change of slope are always present. The change of the Tafel slope is associated to a change of the electrode mechanism, due to the evolution of the chemical nature of the electrode surface from a bare platinum electrode to a polypyrrole coated electrode. The empirical kinetics obtained from the region of lower slope values (coated electrode), are: Rp = Pyrrole[sup x]ClO[sub 4-][sup y], with x = 0.5, for the three studied systems, and y = 0.5, 0.7, 0.5 for acetonitrile, water and acetonitrile/water solutions respectively, in agreement with reaction orders obtained from a gravimetric following of the electrogenerated polymer. (orig.)

Otero, T.F. (U.P.V., Facultad de Quimica, Lab. de Electroquimica, San Sebastian (Spain)); Rodriguez, J. (U.P.V., Facultad de Quimica, Lab. de Electroquimica, San Sebastian (Spain))

1993-03-22

23

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

Comparison of precipitation nowcasting by extrapolation and statistical-advection methods

Two models for nowcasting of 1-h, 2-h and 3-h precipitation in the warm part of the year were evaluated. The first model was based on the extrapolation of observed radar reflectivity (COTREC-IPA) and the second one combined the extrapolation with the application of a statistical model (SAMR). The accuracy of the model forecasts was evaluated on independent data using the standard measures of root-mean-squared-error, absolute error, bias and correlation coefficient as well as by spatial verification methods Fractions Skill Score and SAL technique. The results show that SAMR yields slightly better forecasts during the afternoon period. On the other hand very small or no improvement is realized at night and in the very early morning. COTREC-IPA and SAMR forecast a very similar horizontal structure of precipitation patterns but the model forecasts differ in values. SAMR, similarly as COTREC-IPA, is not able to develop new storms or significantly intensify already existing storms. This is caused by a large uncertainty regarding future development. On the other hand, the SAMR model can reliably predict decreases in precipitation intensity.

Sokol, Zbynek; Kitzmiller, David; Pesice, Petr; Mejsnar, Jan

2013-04-01

25

Model-derived electron and proton auroral FUV emission efficiencies of relevance to auroral FUV remote sensing methods are evaluated using coincident observations by Special Sensor Ultraviolet Spectrographic Imager (SSUSI) and Special Sensor J/5 (SSJ/5), both on board the Defense Meteorological Satellite Program (DMSP) satellite F16. This follows earlier work by Knight et al. (2008), which reported higher than expected proton Lyman-Birge-Hopfield (LBH) emission efficiencies based on F16 SSUSI and SSJ/5 comparisons, and Correira et al. (2011), which suggested a downward revision in the proton LBH efficiencies from Knight et al. (2008). These proton efficiency results rely on proton extrapolation methods to supply the unmeasured proton flux above 30 keV (the upper limit of SSJ/5). Correira et al. (2011) determined that there was a bias in the proton extrapolation method used by Knight et al. (2008) that was caused by column emission rate (CER) thresholding in the coincident SSUSI and SSJ/5 sets. In the latest work, a more robust proton flux extrapolation method is introduced which does not have the problem of CER threshold dependence. The new extrapolation method uses coincident SSUSI Lyman alpha observations to constrain the extrapolated proton flux above 30 keV in such a way that unknown Lyman alpha model yield errors and SSUSI and SSJ/5 calibration errors drop out without biasing the extrapolation. With the latest extrapolation method, SSUSI-SSJ/5 comparisons indicate that proton aurora is typically a factor of ˜4.5 more efficient per unit of energy flux in producing LBH than electron aurora.

Knight, H. K.; Strickland, D. J.; Correira, J.; Hecht, J. H.; Straus, P. R.

2012-11-01

26

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

27

New extrapolation method for low-lying states of nuclei in the sd and the pf shells

International Nuclear Information System (INIS)

We study extrapolation approaches to evaluate energies of low-lying states for nuclei in the sd and pf shells, by sorting the diagonal matrix elements of the nuclear shell-model Hamiltonian. We introduce an extrapolation method with perturbation and apply our new method to predict both low-lying state energies and E2 transition rates between low-lying states. Our predicted results arrive at an accuracy of the root-mean-squared deviations ?40-60 keV for low-lying states of these nuclei.

2011-01-01

28

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 by the spacetime conservation-element and solution-element (CESE) scheme. A magnetic field splitting method is used to further improve the computational accuracy. The bottom boundary condition is prescribed by changing the transverse field incrementally to match the magnetogram, and all other artificial boundaries of the computational box are simply fixed. We examine the code by two types of NLFFF benchmark tests, the Low & Lou (1990) semi-analytic force-free solutions and a more realistic solar-like case constructed by van Ballegooij...

Jiang, Chaowei

2012-01-01

29

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 $r

Justin Steven Prentice

2011-01-01

30

Energy Technology Data Exchange (ETDEWEB)

This study uses ultrasound in combination with tomography to obtain three-dimensional temperature measurements using projection data obtained from limited projection angle. The main feature of the new computerized tomography (CT) reconstruction algorithm is to employ extrapolation scheme to make up for the incomplete projection data, it is based on the conventional filtered back projection (FBP) method while on top of that taking into account the correlation between the projection data and Fourier transform-based extrapolation. Computer simulation is conducted to verify the above algorithm. An experimental 3D temperature distribution measurement is also carried out to validate the proposed algorithm. The simulation and experimental results demonstrate that the extrapolated FBP CT algorithm is highly effective in dealing with projection data from limited projection angle.

Zhu Ning; Jiang Yong; Kato, Seizo

2005-03-01

31

International Nuclear Information System (INIS)

[en] Advantages have been stated in the paper of application of the equivalent scheme of decay of radionuclides with complicated decay scheme and emitting low energy conversion electrons. In th e most cases it is possible to use the effectivity extrapolation method in the linear variant. Application of the equivalent sche me principle is illustrated by standardization of 57Co and 133Ba

1979-01-01

32

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.

Abdullah, Lazim; Rahman, Nurhakimah Ab

2013-04-01

33

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

International Nuclear Information System (INIS)

[en] 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

1978-01-01

34

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.).

1991-01-01

35

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

International Nuclear Information System (INIS)

[en] 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)

1979-01-01

36

Calculation of extrapolation curves in the 4. pi beta. -. gamma. coincidence method

Energy Technology Data Exchange (ETDEWEB)

A program has been realised to calculate theoretically the beta, gamma, and coincidence efficiencies and the extrapolated activity value of a given radionuclide which are obtained by 4..pi beta..-..gamma.. coincidence measurements, from the nuclear decay data and hypothetical detection efficiency values. It is used for studying more easily, especially in the case of complex decay schemes, the influence of the parameters involved. It can calculate a correction factor for obtaining the true activity value under experimental conditions. Some examples are presented; /sup 133/Ba, /sup 51/Cr, /sup 195/Au and /sup 201/Tl.

Chauvenet, B.; Bouchard, J.; Vatin, R.

1987-01-01

37

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.

1982-01-01

38

Numerical reconstruction/extrapolation of coronal nonlinear force-free magnetic field (NLFFF) usually takes the photospheric vector magnetogram as input at the bottom boundary. Magnetic field observed at the photosphere, however, contains force which is in conflict with the fundamental assumption of the force-free model and measurement noise which is unfavorable for practical computation. Preprocessing of the raw magnetogram has been proposed by Wiegelmann, Inhester, and Sakurai (2006) to remove the force and noise for providing better input for NLFFF modeling. In this paper we develop a new code of magnetogram preprocessing which is consistent with our extrapolation method CESE-MHD-NLFFF (Jiang, Feng, and Xiang, 2012; Jiang and Feng, 2012). Basing on a 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 deal with the two parts separately. Preprocessing of the magnetogram's potential part is based on a numerical potentia...

Jiang, Chaowei

2013-01-01

39

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 $O({\\cal N})$ operations where ${\\cal N}$ 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

2012-01-01

40

International Nuclear Information System (INIS)

The absolute standardization of radioactive solutions of low energy beta emitters and beta-gamma emitters with a high probability of disintegration to the ground state is described; the tracer and the efficiency extrapolation methods were used. Both types of radionuclides were mathematically and physically treated in an unified manner. The theoretical relations between different beta spectra were calculated according to Williams' model and experimentally verified for: 35S + 60Co, 35S + 95Nb, 147Pm + 60Co, 14C + 95Nb and two beta branches of 99Mo. The optimum range of beta efficiency variation was indicated. The basic supposition that all beta efficieny tend to unity in the same time was experimentally verified, using two 192Ir beta branches. Four computer programs, written in the FORTRAN IV language, were elaborated, for the adequate processing of the experimental data. Good precision coefficients according to international standards were obtained in the absolute standardization of 35S, 147Pm, 99Mo solutions. (author)

1978-01-01

41

Extraordinarily small Tafel slope for oxide formation reaction on Pt (1 1 1) surface

International Nuclear Information System (INIS)

[en] Oxide formation reaction current density on Pt (1 1 1) was estimated by time-differentiating oxide growth curves during a potential hold as a function of the potential and the coverage with the oxide below 0.35 ML (monolayer). The Tafel slope was 18–24 mV decade?1 in the condition where the Tafel plot is on a straight line. The reaction mechanism accounting for this small slope was proposed, in which the oxide formation process is assumed as a combination of a fast electron transfer step and a following slow step.

2012-09-01

42

Stable explicit depth extrapolation of seismic wavefields

Energy Technology Data Exchange (ETDEWEB)

Stable explicit filters for depth extrapolation of seismic wavefields may be derived through a modification of the conventional Taylor series method. The modified Taylor series method described here yields extrapolators with maximally-flat amplitude spectra in their passband, while ensuring that no spectral components in the wavefield are amplified by any factor greater than one. The price for stability is increased phase error. For low normalized frequencies, implicit extrapolators are more accurate than the 39-coefficient stable explicit extrapolator described here. However, the small spatial sampling intervals required to obtain high phase accuracy in implicit extrapolation imply that this accuracy is rarely achieved in practice. Over the wide range of normalized frequencies likely to be encountered in practice, stable explicit extrapolators outperform implicit ones. The method presented here for deriving stable explicit extrapolators is in no formal sense optimal. It is only guaranteed to yield stable extrapolators. In my limited experience with alternative methods for designing stable extrapolators, the method presented here produced the least phase error while ensuring stability. Nevertheless, a simple method for designing optimal (in some sense) stable explicit extrapolators would be preferred over the method presented here. 7 refs., 15 figs.

Hale, D.

1990-01-01

43

Chiral extrapolation of lattice data

We propose analytic approximations of chiral SU(3) amplitudes for the extrapolation of lattice data to the physical meson masses. The method allows the determination of NNLO low-energy constants in a controllable fashion. We test the approach with recent lattice data for the ratio F_K/F_pi of meson decay constants.

Ecker, Gerhard; Neufeld, Helmut

2010-01-01

44

Extrapolation of stable random fields

In this paper, we discuss three extrapolation methods for alpha-stable random fields with 1

Karcher, Wolfgang; Spodarev, Evgeny

2011-01-01

45

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

46

Quasi-onedimensional stereoregular polymers as for example polyacetylene are currently of considerable interest. There are basically two different approaches for doing electronic structure calculations: One method is essentially based on concepts of solid state theory. The other method is essentially a quantum chemical method since it approximates the polymer by oligomers consisting of a finite number of monomer units. In this way, the highly developed technology of quantum chemical molecular programs can be used. Unfortunately, oligomers of finite size are not necessarily able to model those features of a polymer which crucially depend of its in principle infinite extension. In such a case extrapolation techniques can be extremely helpful. For example, one can perform electronic structure calculations for a sequence of oligomers with an increasing number of monomer units. In the next step, one then can try to determine the limit of this sequence for an oligomer of infinite length with the help of suitable ex...

Weniger, E J

2000-01-01

47

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; N. R. P. Harris; S. B. Andersen; B. Christiansen; N. Larsen; M. Rex; B. Naujokat

2004-01-01

48

Directory of Open Access Journals (Sweden)

Full Text Available When crude petroleum is spilled onto soil, the oil’s properties have a large influence on the toxicity to soil organisms, the biodegradability of the oil, and potential for long term fertility problems in the soil. Furthermore, these properties of environmental concern are related to the crude’s density, commonly measured as API gravity. Currently, methods do not exist to determine the ºAPI of crude oil in contaminated soil. In this study a novel method is presented for the determination of API gravity in small volumes (

Carlos M. Morales-Bautista; Randy H. Adams; Francisco Guzmán-Osorio; Deysi Marín-García

2012-01-01

49

Directory of Open Access Journals (Sweden)

Full Text Available Regarding standards, it is well established that common mode currents are the main source of far field emitted by variable frequency drive (VFD)-cable-motor associations. These currents are generated by the combination of floating potentials with stray capacitances between these floating potential tracks and the mechanical parts connected to the earth (the heatsink or cables are usual examples). Nowadays, due to frequency and power increases, the systematic compliance to EMC (ElectroMagnetic Compatibility) becomes increasingly difficult and costly for industrials. As a consequence, there is a well-identified need to investigate practical and low cost solutions to reduce the radiated fields of VFD-cable-motor associations. A well-adapted solution is the shielding of wound components well known as the major source of near magnetic field. However, this solution is not convenient, it is expensive and may not be efficient regarding far field reduction. Optimizing the components placement could be a better and cheaper solution. As a consequence, dedicated tools have to be developed to efficiently investigate not easy comprehendible phenomena and finally to control EMC disturbances using component placement, layout geometry, shielding design if needed. However, none of the modeling methods usually used in industry complies with large frequency range and far field models including magnetic materials, multilayer PCBs, and shielding. The contribution of this paper is to show that alternatives regarding modeling solutions exist and can be used to get in-deep analysis of such complex structures. It is shown in this paper that near field investigations can give information on far field behavior. It is illustrated by an investigation of near field interactions and shielding influence using a FE-PEEC hybrid method. The test case combining a common mode filter with the floating potentials tracks of an inverter is based on an industrial and commercialized VFD. The near field interactions between the common mode inductance and the tracks with floating potentials are revealed. Then, the influence of the common mode inductance shielding is analyzed.

Edith Clavel; Thanh-Son Tran; Jérémie Aimé; Gérard Meunier; James Roudet

2013-01-01

50

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 are likely to cool the stratosphere further and to increase the amount of polar stratospheric clouds (PSCs). Future Arctic PSC areas have been extrapolated using the highly significant trends in the temperature record from 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 2010–2020 and only decrease slightly up to 2030. This approach is an alternative method of prediction to that based on the complex coupled chemistry-climate models (CCMs).

B. M. Knudsen; S. B. Andersen; B. Christiansen; N. Larsen; M. Rex; N. R. P. Harris; B. Naujokat

2004-01-01

51

UK PubMed Central (United Kingdom)

In vitro-in vivo extrapolation (IVIVE) is an important method for estimating the hepatic metabolic clearance (CL) of drugs. This study highlights a problematic area observed when using microsomal data to predict in vivo CL of drugs that are highly bound to plasma proteins, and further explores mechanisms for human CL predictions by associating additional processes to IVIVE disconnect. Therefore, this study attempts to develop a novel IVIVE calculation method, which consists of adjusting the binding terms in a well-stirred liver model. A comparative assessment between the IVIVE method proposed here and previously published methods of Obach (1999. Drug Metab Dispos 27:1350-1359) and Berezhkovskiy (2010. J Pharm Sci 100:1167-1783) was also performed. The assessment was confined by the availability of measured in vitro and in vivo data in humans for 25 drugs highly bound to plasma proteins, for which it can be assumed that metabolism is the major route of elimination. Here, we argue that a difference in drug ionization and binding proteins such as albumin (AL) and alpha-1-acid glycoprotein (AAG) in plasma and liver also needs to be considered in IVIVE based on mechanistic studies. Therefore, converting unbound fraction in plasma to liver essentially increased the predicted CL values, which resulted in much more accurate estimates of in vivo CL as compared with the other IVIVE methods tested. The impact on CL estimate was more apparent for drugs binding to AL than to AAG. This is a mechanistic rational for explaining a considerable proportion of the divergence between previously estimated and observed CL values. Human CL was predicted within 1.5-fold, twofold, and threefold of the observed CL for 84%, 96%, and 100% of the compounds, respectively. Overall, this study demonstrates a significant improvement in the mechanism-based prediction of metabolic CL for these 25 highly bound drugs from in vitro data determined with microsomes, which should facilitate the application of physiologically based pharmacokinetic (PBPK) models in drug discovery and development.

Poulin P; Kenny JR; Hop CE; Haddad S

2012-02-01

52

SPATIAL EXTRAPOLATION OF ANISOTROPIC ROAD TRAFFIC DATA

Directory of Open Access Journals (Sweden)

Full Text Available A method of spatial extrapolation of traffic data is proposed. The traffic data is given by GPS signals over downtown Berlin sent by approximately 300 taxis. To reconstruct the traffic situation at a given time spatially, i.e., in the form of traffic maps, kriging with moving neighborhood based on residuals is used. Due to significant anisotropy in directed traffic data, the classical kriging has to be modified in order to include additional information. To verify the extrapolation results, test examples on the basis of a well-known model of stochastic geometry, the Boolean random function are considered.

Hans Braxmeier; Volker Schmidt; Evgueni Spodarev

2004-01-01

53

Extrapolated implicit-explicit time stepping.

Energy Technology Data Exchange (ETDEWEB)

This paper constructs extrapolated implicit-explicit time stepping methods that allow one to efficiently solve problems with both stiff and nonstiff components. The proposed methods are based on Euler steps and can provide very high order discretizations of ODEs, index-1 DAEs, and PDEs in the method-of-lines framework. Implicit-explicit schemes based on extrapolation are simple to construct, easy to implement, and straightforward to parallelize. This work establishes the existence of perturbed asymptotic expansions of global errors, explains the convergence orders of these methods, and studies their linear stability properties. Numerical results with stiff ODE, DAE, and PDE test problems confirm the theoretical findings and illustrate the potential of these methods to solve multiphysics multiscale problems.

Constantinescu, E. M.; Sandu, A.; Mathematics and Computer Science; Virginia Polytechnic Inst. and State Univ.

2010-01-01

54

Load Extrapolation During Operation for Wind Turbines

DEFF Research Database (Denmark)

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 method is recommended. In this paper this method is considered and some of the assumptions are examined. The statistical uncertainty related to the limited number of simulations of the response during operation is explored together with the influence of the threshold value.

Toft, Henrik Stensgaard; SØrensen, John Dalsgaard

2008-01-01

55

Chiral extrapolations for nucleon magnetic moments

Lattice quantum chromodynamics (QCD) simulations have made significant progress in the calculation of nucleon electromagnetic form factors in the chiral regime in recent years. With simulation results achieving pion masses of order ~180 MeV, there is an apparent challenge as to how the physical regime is approached. By using contemporary methods in chiral effective field theory, both the quark-mass and finite-volume dependence of the isovector nucleon magnetic moment are carefully examined. The extrapolation to the physical point yields a result that is compatible with experiment, albeit with a combined statistical and systematic uncertainty of 10%. The extrapolation shows a strong finite-volume dependence; lattice sizes of L > 5 fm must be used to simulate results within 2% of the infinite-volume result for the magnetic moment at the physical pion mass.

Hall, J M M; Young, R D

2012-01-01

56

Vertical extrapolations of wind speed

Energy Technology Data Exchange (ETDEWEB)

The extrapolation of wind speeds and wind speed distributions from a lower to an upper level is examined, with particular emphasis on the power law approach. While the power laws are useful for representing the behavior of winds under a variety of conditions, they are shown to be inherently incorrect and misleading for extrapolations. The law's apparent simplicity nevertheless makes it attractive for certain purposes, and its performance at a number of windy sites is tested. The principal feature seems to be the large degree of scatter found from site to site, and even at a single site from one time to the next. Part of this is attributable to the effects of stability, as is seen by dividing the data into daytime and nighttime periods, but the scatter is by no means eliminated by this division. The behavior of the power law exponents is poorer still in complex terrain. While some general tendencies of these exponents can be found, their use cannot be recommended for anything more than a preliminary or rough estimate of wind speeds. Extrapolation formulas for Weibull distributions are also tested with the same data base. They are found to work reasonably well in the mean, but the uncertainties present make their use in any particular case somewhat risky. The use of kites to obtain estimates either of wind speed distributions or power law exponent distributions is simulated. As expected, there is a considerable degree of scatter associated with the results, but the use of kites seems to offer some small possibility of improvement compared to results obtained from the simple extrapolation formulas for Weibull distributions.

Doran, J.C.; Buck, J.W.; Heflick, S.K.

1982-09-01

57

Mechanistic considerations in toxicity extrapolation

Energy Technology Data Exchange (ETDEWEB)

Concerns over extrapolating toxicity from species to species are based in the inherent variability in sensitivity which is seen in the toxicological literature for any given chemical. The development of a rational means of effective extrapolation benefits from understanding the mechanisms underlying this variability. Mechanisms of differential toxicity are rooted in variations in the disposition of, and receptor sensitivity to, the chemical whose toxicity is under evaluation. These are often called toxicokinetic and toxicodynamic characteristics, respectively, An understanding of the mechanistic underpinnings of variations in toxicity improves the quality and accuracy of toxicity extrapolations made between species. Dispositional, or toxicokinetic influences occur due to variability in processes responsible for, or associated with, the absorption, distribution, metabolism and excretion of a chemical. Metabolic processing accounts for a large proportion of the dispositional influence. Species-specific variation in the mechanisms and rates of pro-toxicant activation and active toxicant degradation can lead to substantial differences in the amount of active toxicant that arrives at target tissues. Differences in target site interactions with toxicants occur due to variability in affinity between toxicant and target, availability and quantity of target molecules and the availability of alternative target sites. The latter can be particularly important when metabolic protection mechanisms are lacking in a species. An understanding of the mechanistic basis for extremes in sensitivity or tolerance can be used to predict species of concern or chemical classes and characteristics whose toxicity may pose a risk to particular classes of organisms.

Hooper, M.J. [Clemson Univ., SC (United States)

1995-12-31

58

Extrapolations to critical for systems with large inherent sources

Energy Technology Data Exchange (ETDEWEB)

An approach to delayed critical experiment was performed in 1981 at Pacific Northwest Laboratory with a cylindrical tank of plutonium-uranium nitrate solution. During this experiment, various methods to determine the critical height were used, including (1) extrapolation of the usual plot of inverse count rate vs. height, which estimates the delayed critical height (DCH); (2) the inverse count rate vs. height divided by count rate, which corrects somewhat for the change in inherent source size as the height changes; (3) ratio of spectral densities vs. height, which extrapolates to DCH; (4) extrapolations of prompt neutron decay constant vs. height, which extrapolates to the prompt critical height (PCH); and (5) inverse kinetics rod drop (IKRD) methods, which measure {Delta}k/k{Beta} very accurately for a particular solution height. The problem with some of the extrapolation methods is that the measured data are not linear with height, but, for lack of anything better, linear extrapolations are made. In addition to the measurements to determine the delayed critical height subcriticality measurements by the {sup 252}Cf source driven frequency analysis method were performed for a variety of subcriticality heights. This paper describes how all these methods were applied to obtain the critical height of a cylindrical tank of plutonium nitrate solution and how the subcritical neutron multiplication factor was obtained.

Mihalczo, J.T.; Wyatt, M.S.

1997-07-01

59

Mechanism and Tafel lines of electro-oxidation of water to oxygen on RuO2(110).

UK PubMed Central (United Kingdom)

How to efficiently oxidize H(2)O to O(2) (H(2)O ? 1/2O(2) + 2H(+) + 2e(-)) is a great challenge for electrochemical/photo water splitting owing to the high overpotential and catalyst corrosion. Here extensive periodic first-principles calculations integrated with modified-Poisson-Boltzmann electrostatics are utilized to reveal the physical origin of the high overpotential of the electrocatalytic oxygen evolution reaction (OER) on RuO(2)(110). By determining the surface phase diagram, exploring the possible reaction channels, and computing the Tafel lines, we are able to elucidate some long-standing puzzles on the OER kinetics from the atomic level. We show that OER occurs directly on an O-terminated surface phase above 1.58 V vs NHE, but indirectly on a OH/O mixed phase below 1.58 V by converting first the OH/O mixed phase to the O-terminated phase locally. The rate-determining step of OER involves an unusual water oxidation reaction following a Eley-Rideal-like mechanism, where a water molecule from solution breaks its OH bond over surface Os with concurrent new O-OH bond formation. The free energy barrier is 0.74 eV at 1.58 V, and it decreases linearly with the increase of potential above 1.58 V (a slope of 0.56). In contrast, the traditionally regarded surface oxygen coupling reaction with a Langmuir-Hinshelwood mechanism is energetically less favored and its barrier is weakly affected by the potential. Fundamentally, we show that the empirical linear barrier~potential relation is caused by the linear structural response of the solvated transition state to the change of potential. Finally, the general strategy for finding better OER anode is also presented.

Fang YH; Liu ZP

2010-12-01

60

Mechanism and Tafel lines of electro-oxidation of water to oxygen on RuO2(110).

How to efficiently oxidize H(2)O to O(2) (H(2)O ? 1/2O(2) + 2H(+) + 2e(-)) is a great challenge for electrochemical/photo water splitting owing to the high overpotential and catalyst corrosion. Here extensive periodic first-principles calculations integrated with modified-Poisson-Boltzmann electrostatics are utilized to reveal the physical origin of the high overpotential of the electrocatalytic oxygen evolution reaction (OER) on RuO(2)(110). By determining the surface phase diagram, exploring the possible reaction channels, and computing the Tafel lines, we are able to elucidate some long-standing puzzles on the OER kinetics from the atomic level. We show that OER occurs directly on an O-terminated surface phase above 1.58 V vs NHE, but indirectly on a OH/O mixed phase below 1.58 V by converting first the OH/O mixed phase to the O-terminated phase locally. The rate-determining step of OER involves an unusual water oxidation reaction following a Eley-Rideal-like mechanism, where a water molecule from solution breaks its OH bond over surface Os with concurrent new O-OH bond formation. The free energy barrier is 0.74 eV at 1.58 V, and it decreases linearly with the increase of potential above 1.58 V (a slope of 0.56). In contrast, the traditionally regarded surface oxygen coupling reaction with a Langmuir-Hinshelwood mechanism is energetically less favored and its barrier is weakly affected by the potential. Fundamentally, we show that the empirical linear barrier~potential relation is caused by the linear structural response of the solvated transition state to the change of potential. Finally, the general strategy for finding better OER anode is also presented. PMID:21133410

Fang, Ya-Hui; Liu, Zhi-Pan

2010-12-06

61

International Nuclear Information System (INIS)

[en] Study of the reaction ?-p ? ?-?0 p at 2.77 GeV/c carried out in the CERN 2 meter large liquid hydrogen bubble chamber at the proton synchrotron, shows that 70 per cent of this reaction goes through ?-p ? ?-p channel. The high statistics allow us to specify the mass and the width of the ?- resonance. In other hand, if the ?- production parameters are independent of the ?- width, it is not the same case for the decay parameters. In the second part, the Chew-Low extrapolation method allows us to determine the ?-?0 elastic cross section to the pole, and the phase shifts of the P waves in the isospin 1 state and S waves in the isospin 2 state. (author)

1969-01-01

62

Problems of extrapolating deposit characteristics in coal mining

Energy Technology Data Exchange (ETDEWEB)

An outline of the general problems of precalculation, with particular regard to the extrapolation of deposit characteristics, is followed by a description of the trends in motivation concerning this problem in German coal mining. Requirements on prediction and the resulting problems are gone into. Methods of calculation and sources of errors are listed. A model for optimum extrapolation of deposit characteristics is put up for discussion. The accuracies of different methods are compared, ways of assessing the quality of a method are pointed out, and conclusions are drawn for future investigations.

Leonhardt, J.

1986-02-01

63

Aspects of SU(3) baryon extrapolation

We report on a recent chiral extrapolation, based on an SU(3) framework, of octet baryon masses calculated in 2+1-flavour lattice QCD. Here we further clarify the form of the extrapolation, the estimation of the infinite-volume limit, the extracted low-energy constants and the corrections in the strange-quark mass.

Young, R D

2009-01-01

64

Extrapolations of nuclear binding energies from new linear mass relations

DEFF Research Database (Denmark)

We present a method to extrapolate nuclear binding energies from known values for neighboring 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 initially made for a nucleus by applying each of these relations. Very reliable estimates are then produced either by an average or by choosing the extrapolation where the smoothest structures enter. Corresponding mass relations for Q? values are used to study the general structure of superheavy elements. A minor neutron shell at N=152 is seen, but no sign of other shell structures are apparent in the superheavy region. Accuracies are typically substantially better than 0.5 MeV.

Hove, D.; Jensen, A. S.

2013-01-01

65

Fuzzy Model Comparison to Extrapolate Rainfall Data

Directory of Open Access Journals (Sweden)

Full Text Available This research presents two fuzzy rule-based models for extrapolating the missing rainfall data records of a station, utilizing as a reference the values from another meteorological station located in an adjacent area. The first one is constructed based on the least squares algorithm and the second one using ANFIS method. Three stations were used in this research, all located in Northern Greece. The values of Thessaloniki station were used as fuzzy premises and the values of Sindos and Kria Vrisi were used as fuzzy responses. The model performance was measured by testing several types and numbers of membership functions. Both models are compared with the classical method of linear regression. The comparison between the classical and fuzzy logic method, shows that the second one performs better in recovering the missing rainfall values. It was also found that a fuzzy rule based system, trained with the least squares algorithm, with two fully overlapping fuzzy numbers, is identical to the linear regression method.

C. Tzimopoulos; L. Mpallas; C. Evangelides

2008-01-01

66

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Toft, Henrik Stensgaard; Naess, Arvid; Saha, Nilanjan; Sørensen, John Dalsgaard

67

Frequency extrapolation by nonconvex compressive sensing

Energy Technology Data Exchange (ETDEWEB)

Tomographic imaging modalities sample subjects with a discrete, finite set of measurements, while the underlying object function is continuous. Because of this, inversion of the imaging model, even under ideal conditions, necessarily entails approximation. The error incurred by this approximation can be important when there is rapid variation in the object function or when the objects of interest are small. In this work, we investigate this issue with the Fourier transform (FT), which can be taken as the imaging model for magnetic resonance imaging (MRl) or some forms of wave imaging. Compressive sensing has been successful for inverting this data model when only a sparse set of samples are available. We apply the compressive sensing principle to a somewhat related problem of frequency extrapolation, where the object function is represented by a super-resolution grid with many more pixels than FT measurements. The image on the super-resolution grid is obtained through nonconvex minimization. The method fully utilizes the available FT samples, while controlling aliasing and ringing. The algorithm is demonstrated with continuous FT samples of the Shepp-Logan phantom with additional small, high-contrast objects.

Chartrand, Rick [Los Alamos National Laboratory; Sidky, Emil Y [UNIV OF CHICAGO; Pan, Xiaochaun [UNIV OF CHICAGO

2010-12-03

68

Surrogate endpoint analysis: an exercise in extrapolation.

UK PubMed Central (United Kingdom)

Surrogate endpoints offer the hope of smaller or shorter cancer trials. It is, however, important to realize they come at the cost of an unverifiable extrapolation that could lead to misleading conclusions. With cancer prevention, the focus is on hypothesis testing in small surrogate endpoint trials before deciding whether to proceed to a large prevention trial. However, it is not generally appreciated that a small surrogate endpoint trial is highly sensitive to a deviation from the key Prentice criterion needed for the hypothesis-testing extrapolation. With cancer treatment, the focus is on estimation using historical trials with both surrogate and true endpoints to predict treatment effect based on the surrogate endpoint in a new trial. Successively leaving out one historical trial and computing the predicted treatment effect in the left-out trial yields a standard error multiplier that summarizes the increased uncertainty in estimation extrapolation. If this increased uncertainty is acceptable, three additional extrapolation issues (biological mechanism, treatment following observation of the surrogate endpoint, and side effects following observation of the surrogate endpoint) need to be considered. In summary, when using surrogate endpoint analyses, an appreciation of the problems of extrapolation is crucial.

Baker SG; Kramer BS

2013-03-01

69

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; Peševski Igor; Papi? Jovan Br.

2012-01-01

70

Cosmogony as an extrapolation of magnetospheric research

International Nuclear Information System (INIS)

[en] 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)

1984-01-01

71

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 mus...

Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

72

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

73

Survival extrapolation using the poly-Weibull model.

Recent studies of (cost-) effectiveness in cardiothoracic transplantation have required estimation of mean survival over the lifetime of the recipients. In order to calculate mean survival, the complete survivor curve is required but is often not fully observed, so that survival extrapolation is necessary. After transplantation, the hazard function is bathtub-shaped, reflecting latent competing risks which operate additively in overlapping time periods. The poly-Weibull distribution is a flexible parametric model that may be used to extrapolate survival and has a natural competing risks interpretation. In addition, treatment effects and subgroups can be modelled separately for each component of risk. We describe the model and develop inference procedures using freely available software. The methods are applied to two problems from cardiothoracic transplantation. PMID:21937472

Demiris, Nikolaos; Lunn, David; Sharples, Linda D

2011-11-21

74

Survival extrapolation using the poly-Weibull model.

UK PubMed Central (United Kingdom)

Recent studies of (cost-) effectiveness in cardiothoracic transplantation have required estimation of mean survival over the lifetime of the recipients. In order to calculate mean survival, the complete survivor curve is required but is often not fully observed, so that survival extrapolation is necessary. After transplantation, the hazard function is bathtub-shaped, reflecting latent competing risks which operate additively in overlapping time periods. The poly-Weibull distribution is a flexible parametric model that may be used to extrapolate survival and has a natural competing risks interpretation. In addition, treatment effects and subgroups can be modelled separately for each component of risk. We describe the model and develop inference procedures using freely available software. The methods are applied to two problems from cardiothoracic transplantation.

Demiris N; Lunn D; Sharples LD

2011-11-01

75

Implicit 3-D depth migration by wavefield extrapolation with

UK PubMed Central (United Kingdom)

Wavefield extrapolation in the (#x) domain provides a tool for depth migration withstrong lateral variations in velocity. Implicit formulations of depth extrapolation have severaladvantages over explicit methods. However, the simple 3-D extension of conventional2-D wavefield extrapolation by implicit finite-differencing requires the inversion of a 2Dconvolution matrix which is computationally difficult. In this paper, we solve the 45 #wave equation with helical boundary conditions on one of the spatial axes. These boundaryconditions reduce the 2-D convolution into an equivalent 1-D filter operation. We thenfactor this 1-D filter into causal and anti-causal parts using an extension of Kolmogoroff'sspectral factorization method, and invert the convolution operator efficiently by 1-D recursivefiltering. We include lateral variations in velocity by factoring spatially variablefilters, and non-stationary deconvolution. The helical boundary conditions allow the 2-Dconvolution matrix to be inverted directly without the need for splitting approximations,with a cost that scales linearly with the size of the model space. Using this methodology,a whole range of implicit depth migrations may now be feasible in 3-D.

James Rickett; Jon Claerbout; Sergey Fomel

76

Extrapolated HPGe efficiency estimates based on a single calibration measurement

International Nuclear Information System (INIS)

Gamma spectroscopists often must analyze samples with geometries for which their detectors are not calibrated. The effort to experimentally recalibrate a detector for a new geometry can be quite time consuming, causing delay in reporting useful results. Such concerns have motivated development of a method for extrapolating HPGe efficiency estimates from an existing single measured efficiency. Overall, the method provides useful preliminary results for analyses that do not require exceptional accuracy, while reliably bracketing the credible range. The estimated efficiency element-of for a uniform sample in a geometry with volume V is extrapolated from the measured element-of 0 of the base sample of volume V0. Assuming all samples are centered atop the detector for maximum efficiency, element-of decreases monotonically as V increases about V0, and vice versa. Extrapolation of high and low efficiency estimates element-of h and element-of L provides an average estimate of element-of = 1/2 [element-of h + element-of L] ± 1/2 [element-of h - element-of L] (general) where an uncertainty D element-of = 1/2 (element-of h - element-of L] brackets limits for a maximum possible error. The element-of h and element-of L both diverge from element-of 0 as V deviates from V0, causing D element-of to increase accordingly. The above concepts guided development of both conservative and refined estimates for element-of

1994-01-01

77

Chiral extrapolations for nucleon electric charge radii

Lattice simulations for the electromagnetic form factors of the nucleon yield insights into the internal structure of hadrons. The logarithmic divergence of the charge radius in the chiral limit poses an interesting challenge in achieving reliable predictions from finite-volume lattice simulations. Recent results near the physical pion mass are examined in order to confront the issue of how the chiral regime is approached. The electric charge radius of the nucleon presents a forum for achieving consistent finite-volume corrections. Newly-developed techniques within the framework of chiral effective field theory are used to achieve a robust extrapolation of the electric charge radius to the physical pion mass, and to infinite volume. The chiral extrapolations exhibit considerable finite-volume dependence; lattice box sizes of L > 7 fm are required in order to achieve a direct lattice simulation result within 2% of the infinite-volume value at the physical point. Predictions of the volume-dependence are provide...

Hall, J M M; Young, R D

2013-01-01

78

Experiences and extrapolations from Hiroshima and Nagasaki

International Nuclear Information System (INIS)

This chapter examines events following the atomic bombings of Hiroshima and Nagasaki in 1945 and extrapolates from these experiences in an attempt to understand the possible consequences of detonations on a local area from weapons in the current world nuclear arsenal. The limitations of drawing upon the Hiroshima and Nagasaki experiences are discussed. Comparison is made of the scale of effects from other major disasters for urban systems, such as damages from conventional bombings, consequences of major earthquakes, historical effects of the Black Plague, widespread famines and other extreme natural events. It is concluded that mere extrapolation from the experiences of Hiroshima and Nagasaki has consistently led to a gross underestimation of what the consequences of the next nuclear war would be for the global human population. (UK)

1985-01-01

79

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)

2001-01-01

80

Explicit calculation of track extrapolation error

Energy Technology Data Exchange (ETDEWEB)

This paper presents a set of explicit formulas for calculating the track extrapolation errors of charged particles by small-step iterations. Formulas are also given to calculate the projected track errors and Kalman filtering for planar detectors, which are located in the dense material. The result can be used to find matches of the hits to the track in the downstream detector, such as in a muon detector.

Teramoto, Yoshiki E-mail: teramoto@hep.osaka-cu.ac.jp

2000-07-11

81

The "hazards" of extrapolating survival curves.

UK PubMed Central (United Kingdom)

BACKGROUND: It is widely recommended that health technology appraisals adopt a lifetime horizon to assess the relative costs and benefits of an intervention. However, most trials or clinical studies have relatively short follow-up periods, with the event of interest not occurring before the end of the study for many subjects. In such cases, survival analysis using parametric models can be used to extrapolate into the future. OBJECTIVE: To assess the accuracy of survival analysis in projecting future events beyond the sample estimation period. DESIGN: Using a previously published comparison of 2 alternative hip replacement prostheses based on 8 years of data as a case study, we extend the data set to include 8 years more data. Using the new data, the parametric assumptions of the previous study and its success in predicting the outcomes are assessed. RESULTS: The extended data set casts doubt on the previous study's findings. The failure curves of the 2 prostheses now cross, and the proportional hazards assumption no longer holds. Extrapolations from the original data set yielded very good predictions for one prosthesis for the full 16 years but were much poorer for the other, even when the proportionality assumption was relaxed. CONCLUSIONS: Care should be taken when extrapolating treatment benefits for new technologies early in their life cycle based on observational or randomized controlled trial data sources. This case study reveals that predictions of prosthesis failure based on a short follow-up period were inaccurate compared with those after a longer period of follow-up.

Davies C; Briggs A; Lorgelly P; Garellick G; Malchau H

2013-04-01

82

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

83

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

UK PubMed Central (United Kingdom)

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.

Joseph W; Verloock L; Goeminne F; Vermeeren G; Martens L

2012-09-01

84

Experiences and extrapolations from Hiroshima and Nagasaki

International Nuclear Information System (INIS)

[en] This paper examines the events following the atomic bombings of Hiroshima and Nagasaki in 1945 and extrapolates from these experiences to further understand the possible consequences of detonations on a local area from weapons in the current world nuclear arsenal. The first section deals with a report of the events that occurred in Hiroshima and Nagasaki just after the 1945 bombings with respect to the physical conditions of the affected areas, the immediate effects on humans, the psychological response of the victims, and the nature of outside assistance. Because there can be no experimental data to validate the effects on cities and their populations of detonations from current weapons, the data from the actual explosions on Hiroshima and Nagasaki provide a point of departure. The second section examines possible extrapolations from and comparisons with the Hiroshima and Nagasaki experiences. The limitations of drawing upon the Hiroshima and Nagasaki experiences are discussed. A comparison is made of the scale of effects from other major disasters for urban systems, such as damages from the conventional bombings of cities during World War II, the consequences of major earthquakes, the historical effects of the Black Plague and widespread famines, and other extreme natural events. The potential effects of detonating a modern 1 MT warhead on the city of Hiroshima as it exists today are simulated. This is extended to the local effects on a targeted city from a global nuclear war, and attention is directed to problems of estimating the societal effects from such a war

1985-01-01

85

Extrapolation models: Absolute and relative risk

International Nuclear Information System (INIS)

For lifetime experiences concerning the radiation-induced frequency of cancer, there are only a few data available form any of the larger epidemiological studies. Appropriate models must therefore be developed to extrapolate the limited period of life of those irradiated persons that were examined in these studies. Basically, two models may be differentiated for defining the radiation risk after a certain length of study and for extrapolating the risk for the irradiated persons over the actual length of the study. The absolute risk model is based on the assumption that radiation-induced cancer cases occur on a constant level or reach a maximum after a certain latency period, in addition to the spontaneously occurring cancer cases. For the relative risk model it is assumend that radiation-induced cancer increases proportionally to the spontaneous cases. The doubling dose, i.e. the dose which doubles the spontaneous risk, is a particular form of the relative risk and is used specifically for genetic radiation effect. From recent data is more and more apparent that epidemiological findings are better described by a relative rather than an absolute risk model. In consequence of a relative risk projection, the values for the assessed radiation risk are expected to be higher. (orig.).

1991-01-01

86

A New Code for Nonlinear Force-Free Field Extrapolation of the Global Corona

Reliable measurements of the solar magnetic field are still restricted to the photosphere, and our present knowledge of the three-dimensional coronal magnetic field is largely based on extrapolation from photospheric magnetogram using physical models, e.g., the nonlinear force-free field (NLFFF) model as usually adopted. Most of the currently available NLFFF codes have been developed with computational volume like Cartesian box or spherical wedge while a global full-sphere extrapolation is still under developing. A high-performance global extrapolation code is in particular urgently needed considering that Solar Dynamics Observatory (SDO) can provide full-disk magnetogram with resolution up to $4096\\times 4096$. In this work, we present a new parallelized code for global NLFFF extrapolation with the photosphere magnetogram as input. The method is based on magnetohydrodynamics relaxation approach, the CESE-MHD numerical scheme and a Yin-Yang spherical grid that is used to overcome the polar problems of the sta...

Jiang, Chaowei; Xiang, Changqing

2012-01-01

87

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.

2011-01-01

88

A Test for Coronal Magnetic Field Extrapolations

UK PubMed Central (United Kingdom)

As models for the physical properties of the corona above solar active regionsgrow more sophisticated, we will require better means for testing them. Inthis paper we discuss and apply such a test to a magnetic field model for anactive region. This test is based on the expectation that the temperatures atdifferent points on a given magnetic field line should be well correlated, dueto the rapid transport of heat along field lines in the corona. We use radioobservations of an active region to measure the temperatures on field lines asthey cross two isogauss surfaces (at 430 and 750 G) in the corona. The fieldlines and isogauss surfaces are derived from a coronal magnetic field modelobtained via a nonlinear force--free field extrapolation of a photospheric vectormagnetogram; for comparison, we also investigate a potential--field extrapolationof the same magnetogram. In a region where strongly sheared fields are present,the nonlinear force--free field model does indeed show a go...

Jeongwoo Lee; Stephen M. White; Mukul R. Kundu; A. N. Mcclymont

89

Extrapolation of Extreme Response for Wind Turbines based on FieldMeasurements

DEFF Research Database (Denmark)

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 independent and that peaks extracted are independent. In the present paper two new methods for loads extrapolation are presented. The first method is based on the same assumptions as the existing method but the statistical extrapolation is only performed for a limited number of mean wind speeds where the extreme load is likely to occur. For the second method the mean wind speeds are divided into storms which are assumed independent and the characteristic loads are determined from the extreme load in each storm.

Toft, Henrik Stensgaard; SØrensen, John Dalsgaard

2009-01-01

90

Energy Technology Data Exchange (ETDEWEB)

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.

Crawford, D.J.; Richmond, C.R.

1980-01-01

91

UK PubMed Central (United Kingdom)

Hot-wire spirometer is a kind of constant temperature anemometer (CTA). The working principle of CTA, used for the measurement of fluid velocity and flow turbulence, is based on convective heat transfer from a hot-wire sensor to a fluid being measured. The calibration curve of a CTA is nonlinear and cannot be easily extrapolated beyond its calibration range. Therefore, a method for extrapolation of CTA calibration curve will be of great practical application. In this paper, a novel approach based on the conventional neural network and self-organizing map (SOM) method has been proposed to extrapolate CTA calibration curve for measurement of velocity in the range 0.7-30 m/seconds. Results show that, using this approach for the extrapolation of the CTA calibration curve beyond its upper limit, the standard deviation is about -0.5%, which is acceptable in most cases. Moreover, this approach for the extrapolation of the CTA calibration curve below its lower limit produces standard deviation of about 4.5%, which is acceptable in spirometry applications. Finally, the standard deviation on the whole measurement range (0.7-30 m/s) is about 1.5%.

Ardekani MA; Nafisi VR; Farhani F

2012-10-01

92

Problems with using mechanisms to solve the problem of extrapolation.

UK PubMed Central (United Kingdom)

Proponents of evidence-based medicine and some philosophers of science seem to agree that knowledge of mechanisms can help solve the problem of applying results of controlled studies to target populations ('the problem of extrapolation'). We describe the problem of extrapolation, characterize mechanisms, and outline how mechanistic knowledge might be used to solve the problem. Our main thesis is that there are four often overlooked problems with using mechanistic knowledge to solve the problem of extrapolation. First, our understanding of mechanisms is often (and arguably, likely to remain) incomplete. Secondly, knowledge of mechanisms is not always applicable outside the tightly controlled laboratory conditions in which it is gained. Thirdly, mechanisms can behave paradoxically. Fourthly, as Daniel Steel points out, using mechanistic knowledge faces the problem of the 'extrapolator's circle'. At the same time, when the problems with mechanistic knowledge have been addressed, such knowledge can and should be used to mitigate (nothing can entirely solve) the problem of extrapolation.

Howick J; Glasziou P; Aronson JK

2013-08-01

93

Increased identification of veterinary pharmaceutical contaminants in aquatic environments has raised concerns regarding potential adverse effects of these chemicals on non-target organisms. The purpose of this work was to develop a method for predictive species extrapolation ut...

94

Trace correcting density matrix extrapolation in self-consistent geometry optimization.

A linear scaling trace correcting density matrix extrapolation method is proposed for accelerated self-consistency convergence in geometry optimization. The technique is based on nonorthogonal trace correcting purification and perturbation theory. Compared with alternative schemes, extrapolated total energies are often an order of magnitude closer to the self-consistent solution. For insulators, the computational cost is low and it scales linearly with the size of the perturbed region affected by the modified geometry, O(N(pert)). For local perturbations, the computational cost is therefore independent of the total size of the system and scales as O(1). PMID:20370111

Niklasson, Anders M N; Challacombe, Matt; Tymczak, C J; Németh, Károly

2010-03-28

95

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

International Nuclear Information System (INIS)

[en] 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)

1976-03-01

96

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, axial flux extrapolation distances are required. For this an analysis is carried out considering the reactor core as 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)

1976-03-03

97

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 registr...

Bopp, M; Zellweger, U; Faeh, D

98

Extrapolation and phase correction of non-uniformly broadened signals.

UK PubMed Central (United Kingdom)

The initial part of FID-signals cannot always be acquired experimentally. This is particularly true for signals characterised by strong inhomogeneous broadening, such as those in porous materials, e.g. cements, soils and rocks, those measured by portable NMR-apparatus, or EPR-signals. Here we report on a numerical method we designed to extrapolate those initial missing parts, i.e. to retrieve their amplitude and phase. Should the entire signal be available from an experiment, the algorithm can still be used as an automatic phase-corrector and a low-pass filter. The method is based on the use of cardinal series, applies to any oversampled signals and requires no prior knowledge of the system under study. We show that the method can also be used to restore entire one-dimensional MRI-data sets from those in which less than half of the k-space was sampled, thus not only potentially allowing to speed up data acquisition - when extended to two or three dimensions, but also to circumvent phase-distortions usually encountered when exploring the k-space near its origin.

Rodts S; Bytchenkoff D

2013-08-01

99

Extrapolation of nuclear properties to the region near Z=1841

International Nuclear Information System (INIS)

[en] The authors compare the extrapolation of nuclear properties to superheavy nuclei by means of the liquid drop model, a simple density functional model, Skyrme-force Hartree-Fock calculations, and a relativistic mean-field approach. (HSI)

1987-01-01

100

Extrapolation of Spectral Signatures Illustrates LANDSATs' Potential to Detect Wetlands.

Spectral signatures of a wetland area were determined using LANDSAT MSS data, hydromorphic soil information, and a pixel extraction technique. Investigations indicate that wetlands could be identified and that the same wetland signatures could be extrapol...

A. Howman

1988-01-01

101

Extrapolated ranges of electrons determined from transmission and projected-range straggling curves

Energy Technology Data Exchange (ETDEWEB)

Extrapolated ranges of electrons R{sub ex,t} and R{sub ex,p} have been determined from transmission and projected-range straggling curves, respectively. Data on the two kinds of curve have been obtained by Monte Carlo calculations for 0.1-50 MeV electrons incident on elemental absorbers of atomic numbers between 4 and 92. The two sets of extrapolated ranges, as well as another set, R{sub ex,q}, determined from charge-deposition curves (Nucl. Instrum. Methods B 119 (4) (1996) 463), have been found practically the same. Appreciable differences of R{sub ex,t} from R{sub ex,p} and R{sub ex,q} have been observed only for electrons of energies below 2 MeV incident on absorbers of the highest atomic numbers. The cause of these differences has been traced to the backscattering of electrons from the incident surface, phenomenon affecting only R{sub ex,t} among the extrapolated ranges determined by the three methods. The fact that the extrapolated range is in most cases independent of the method of determination establishes the usefulness of this quantity. An analytic expression fitted to the Monte Carlo results of R{sub ex,t} is given.

Tabata, Tatsuo E-mail: tttabata@pearl.ocn.ne.jp; Moskvin, Vadim; Andreo, Pedro; Lazurik, Valentin; Rogov, Yuri

2002-06-01

102

Role of animal studies in low-dose extrapolation

Energy Technology Data Exchange (ETDEWEB)

Current data indicate that in the case of low-LET radiation linear, extrapolation from data obtained at high doses appears to overestimate the risk at low doses to a varying degree. In the case of high-LET radiation, extrapolation from data obtained at doses as low as 40 rad (0.4 Gy) is inappropriate and likely to result in an underestimate of the risk.

Fry, R.J.M.

1981-01-01

103

Role of animal studies in low-dose extrapolation

International Nuclear Information System (INIS)

Current data indicate that in the case of low-LET radiation linear, extrapolation from data obtained at high doses appears to overestimate the risk at low doses to a varying degree. In the case of high-LET radiation, extrapolation from data obtained at doses as low as 40 rad (0.4 Gy) is inappropriate and likely to result in an underestimate of the risk.

1981-04-29

104

In this paper, the availability, applicability and deviation of nonlinear force-free (NLFF) fields extrapolated by Approximate Vertical Integration (AVI), Boundary Integral Equation (BIE) and Optimization (Opt.) methods are studied based on the comparison with two semi-analytical fields (Low & Lou 1990). These NLFF extrapolations based on the observational vector magnetograms are used to study the spatial magnetic field in the quiet Sun.

Liu, Suo; Zhang, Hongqi; Su, Jiangtao; Song, Mutao

2013-07-01

105

Delayed inhibition of an anticipatory action during motion extrapolation

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Continuous visual information is important for movement initiation in a variety of motor tasks. However, even in the absence of visual information people are able to initiate their responses by using motion extrapolation processes. Initiation of actions based on these cognitive processes, however, can demand more attentional resources than that required in situations in which visual information is uninterrupted. In the experiment reported we sought to determine whether the absence of visual information would affect the latency to inhibit an anticipatory action. Methods The participants performed an anticipatory timing task where they were instructed to move in synchrony with the arrival of a moving object at a determined contact point. On 50% of the trials, a stop sign appeared on the screen and it served as a signal for the participants to halt their movements. They performed the anticipatory task under two different viewing conditions: Full-View (uninterrupted) and Occluded-View (occlusion of the last 500 ms prior to the arrival at the contact point). Results The results indicated that the absence of visual information prolonged the latency to suppress the anticipatory movement. Conclusion We suggest that the absence of visual information requires additional cortical processing that creates competing demand for neural resources. Reduced neural resources potentially causes increased reaction time to the inhibitory input or increased time estimation variability, which in combination would account for prolonged latency.

Marinovic Welber; Reid Campbell S; Plooy Annaliese M; Riek Stephan; Tresilian James R

2010-01-01

106

Scientific Electronic Library Online (English)

Full Text Available 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 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 seguinte (more) s 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. 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 (more) (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.

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

2010-02-01

107

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; Nilson Oleskovicz; Aury Nunes de Moraes; Fabíola Niederauer Flôres; André Luís Corrêa; Júlio César Souza Júnior; André Vasconcelos Soares; Átila Costa

2010-01-01

108

Energy Technology Data Exchange (ETDEWEB)

An attempt is made to understand the nature of the statistical errors inherent in a method of analytic extrapolation of a discrepancy function which was recently used to estimate the effective KNY coupling constant from experimental data on Ksup(+-)p forward scattering. The method is applied to simulated data generated from a model function which has the general features of the actual scattering amplitude and which incorporates a known value of the coupling constant. It is found that the output value of the coupling constant obtained from this method of extrapolation is subject to uncertainties which are not reflected by the standard error-matrix technique for estimating the statistical errors in fits to error-affected data. The implications of these results for such fits are discussed.

Atkin, G.K.; Claudio, B. di; Violini, G.; Bowcock, J.E.; Queen, N.M.

1981-01-01

109

Vertical extrapolation of windspeeds for mean values and load cases

Energy Technology Data Exchange (ETDEWEB)

A complete set of data cannot be provided by measurements at all sites for which information on the wind field is required. However, there are nearly always values available at the level of 10 metres above the ground. It is necessary to have a process for assessing sites for wind turbines, which permits a first estimate to be made using extrapolation of the wind speeds at heights of 100 and 150 metres. Extrapolation from squalls of wind at 10 metres to greater heights is only possible to a limited extent.

Tetzlaff, G.; Laude, H.; Moeller, L.; Windheim, R. (ed.)

1981-11-01

110

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

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

A study on extrapolation algorithm of percent depth dose

International Nuclear Information System (INIS)

A mathematical model of extrapolating percent depth dose (PDD) was presented according to the principle of interaction between X-ray and water. The difference of extrapolated PDD by the model and measured PDD by 3D radiation field analyzer is very small. For fields of different sizes within 20cm depth, the maximum absolute difference is 0.006 x 100% and the maximum relative difference is 1.1%. With the mathematical model, appropriate PDD values for different field sizes can be abstained without 3D radiation field analyses

2001-01-01

112

Calibration of 90Sr+90Y chemical applicators using a mini extrapolation chamber as reference system

International Nuclear Information System (INIS)

90Sr + 90Y clinical applicators are beta radiation sources utilized in several radiotherapy Brazilian clinics, although don't be more manufactured. These sources are employed in brachytherapy procedures for the treatment of superficial lesions of skin and eyes. International recommendations and previous works determine that dermatological and ophthalmic applicators shall be calibrated periodically, and one of the methods for their calibration consists of the use of an extrapolation chamber. In this work, a method of calibration of 90Sr + 90Y clinical applicators was applied using a mini-extrapolation chamber of plane window, developed at the Calibration Laboratory at IPEN, as a reference system. The results obtained were considered satisfactory, when compared with the results given in the calibration certificates of the sources. (author)

2009-01-01

113

UK PubMed Central (United Kingdom)

The application of fourth order discretisations of the second derivative of concentration with respect to distance from the electrode, in electrochemical digital simulations, is examined. In the bulk of the diffusion space, a central five-point scheme is used, and six-point asymmetric schemes are used at the edges. In this paper, the scheme is applied to the extrapolation technique, based on the backward implicit (BI) algorithm for temporal integration, which (with extrapolation) allows higher orders in time as well. The method is found to be stable, using both the von Neumann and matrix methods. Exceptional efficiency is obtained both for Cottrell and chronopotentiometry simulations, requiring as few as 3-5 steps in time, starting at the dimensionless time t = 0 to gain four-decimal accuracy at t = 1.

Strutwolf J; Britz D

2001-09-01

114

UK PubMed Central (United Kingdom)

The application of fourth order discretisations of the second derivative of concentration with respect to distance from the electrode, in electrochemical digital simulations, is examined. In the bulk of the diffusion space, a central five-point scheme is used, and six-point asymmetric schemes are used at the edges. In this paper, the scheme is applied to the extrapolation technique, based on the backward implicit (BI) algorithm for temporal integration, which (with extrapolation) allows higher orders in time as well. The method is found to be stable, using both the von Neumann and matrix methods. Exceptional efficiency is obtained both for Cottrell and chronopotentiometry simulations, requiring as few as 3-5 steps in time, starting at the dimensionless time t = 0 to gain four-decimal accuracy at t = 1.

Strutwolf J; Britz D

2001-03-01

115

The application of fourth order discretisations of the second derivative of concentration with respect to distance from the electrode, in electrochemical digital simulations, is examined. In the bulk of the diffusion space, a central five-point scheme is used, and six-point asymmetric schemes are used at the edges. In this paper, the scheme is applied to the extrapolation technique, based on the backward implicit (BI) algorithm for temporal integration, which (with extrapolation) allows higher orders in time as well. The method is found to be stable, using both the von Neumann and matrix methods. Exceptional efficiency is obtained both for Cottrell and chronopotentiometry simulations, requiring as few as 3-5 steps in time, starting at the dimensionless time t = 0 to gain four-decimal accuracy at t = 1. PMID:11513241

Strutwolf, J; Britz, D

2001-09-01

116

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

1976-10-08

117

Enhancing Robustness to Extrapolate Synergies Learned from Motion Capture

Digital Repository Infrastructure Vision for European Research (DRIVER)

Reproducing the characteristics of human movements, is a crucial issue in studying motion. In the context of this work, an explicit model of synergies which can be parametrized is used for reproducing the main features of reaching motions. This paper evaluates the possibility to extrapolate learned ...

Aubry, Matthieu; De Loor, Pierre; Gibet, Sylvie

118

Extrapolation and Local Acceleration of an Iterative Process for Common Fixed Point Problems

We consider sequential iterative processes for the common fixed point problem of families of cutter operators on a Hilbert space. These are operators that have the property that, for any point x\\inH, the hyperplane through Tx whose normal is x-Tx always "cuts" the space into two half-spaces one of which contains the point x while the other contains the (assumed nonempty) fixed point set of T. We define and study generalized relaxations and extrapolation of cutter operators and construct extrapolated cyclic cutter operators. In this framework we investigate the Dos Santos local acceleration method in a unified manner and adopt it to a composition of cutters. For these we conduct convergence analysis of successive iteration algorithms.

Cegielski, Andrzej

2012-01-01

119

Outline of the uncertainty methodology based on accuracy extrapolation

Energy Technology Data Exchange (ETDEWEB)

Uncertainty methodology based on accuracy extrapolation (UMAE) is outlined. This methodology is suitable for evaluating the uncertainty in the prediction of transient scenarios in nuclear reactors when carried out by thermal-hydraulic system codes. It is based on the extrapolation of the accuracy resulting from a comparison between code results and relevant experimental data obtained in small scale facilities. A simplified diagram of the UMAE is compared with a similar one derived for the code scaling, applicability and uncertainty evaluation (CSAU) previously proposed by the US Nuclear Regulatory Commission. A few results related to the full application of the UMAE to a small-break loss-of-coolant accident in a pressurized water reactor, including core uncovery, are also reported.

D`Auria, F.; Galassi, G.M. [Univ. of Pisa (Italy); Debrecin, N. [Univ. of Zagreb (Croatia)

1995-01-01

120

Extrapolation of supersymmetry-breaking parameters to high energy scales

Energy Technology Data Exchange (ETDEWEB)

The author studies how well one can extrapolate the values of supersymmetry-breaking parameters to very high energy scales using future data from the Large Hadron Collider and an e{sup +}e{sup -} linear collider. He considers tests of the unification of squark and slepton masses in supergravity-inspired models. In gauge-mediated supersymmetry breaking models, he assess the ability to measure the mass scales associated with supersymmetry breaking. He also shows that it is possible to get good constraints on a scalar cubic stop-stop-Higgs couplings near the high scale. Different assumptions with varying levels of optimism about the accuracy of input parameter measurements are made, and their impact on the extrapolated results is documented.

Stephen P Martin

2002-11-07

121

Application of the Weibull extrapolation to 137Cs geochronology in Tokyo Bay and Ise Bay, Japan.

Considerable doubt surrounds the nature of processes by which 137Cs is deposited in marine sediments, leading to a situation where 137Cs geochronology cannot be always applied suitably. Based on extrapolation with Weibull distribution, the maximum concentration of 137Cs derived from asymptotic values for cumulative specific inventory was used to re-establish 137Cs geochronology, instead of original 137Cs profiles. Corresponding dating results for cores in Tokyo Bay and Ise Bay, Japan, by means of this new method, are in much closer agreement with those calculated from 210Pb method than the previous method. PMID:15023446

Lu, Xueqiang

2004-01-01

122

Application of the Weibull extrapolation to 137Cs geochronology in Tokyo Bay and Ise Bay, Japan.

UK PubMed Central (United Kingdom)

Considerable doubt surrounds the nature of processes by which 137Cs is deposited in marine sediments, leading to a situation where 137Cs geochronology cannot be always applied suitably. Based on extrapolation with Weibull distribution, the maximum concentration of 137Cs derived from asymptotic values for cumulative specific inventory was used to re-establish 137Cs geochronology, instead of original 137Cs profiles. Corresponding dating results for cores in Tokyo Bay and Ise Bay, Japan, by means of this new method, are in much closer agreement with those calculated from 210Pb method than the previous method.

Lu X

2004-01-01

123

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

1984-01-01

124

Continuum extrapolation of $B_K$ with staggered fermions

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

125

We present a technique to improve the least squares (LS) extrapolation of Earth orientation parameters (EOPs), consisting of fixing the last observed data point on the LS extrapolation curve, which customarily includes a polynomial and a few sinusoids. For the polar motion (PM), a more sophisticated two steps approach has been developed, which consists of estimating the amplitude of the more stable one of the annual (AW) and Chandler (CW) wobbles using data of longer time span, and then estimating the other parameters using a shorter time span. The technique is studied using hindcast experiments, and justified using year-by-year statistics of 8 years. In order to compare with the official predictions of the International Earth Rotation and Reference Systems Service (IERS) performed at the U.S. Navy Observatory (USNO), we have enforced short-term predictions by applying the ARIMA method to the residuals computed by subtracting the LS extrapolation curve from the observation data. The same as at USNO, we have also used atmospheric excitation function (AEF) to further improve predictions of UT1-UTC. As results, our short-term predictions are comparable to the USNO predictions, and our long-term predictions are marginally better, although not for every year. In addition, we have tested the use of AEF and oceanic excitation function (OEF) in PM prediction. We find that use of forecasts of AEF alone does not lead to any apparent improvement or worsening, while use of forecasts of AEF + OEF does lead to apparent improvement.

Guo, J. Y.; Li, Y. B.; Dai, C. L.; Shum, C. K.

2013-10-01

126

Extrapolating Monte Carlo simulations to infinite volume: Finite-size scaling at ?/L much-gt 1

International Nuclear Information System (INIS)

We present a simple and powerful method for extrapolating finite-volume Monte Carlo data to infinite volume, based on finite-size-scaling theory. We discuss carefully its systematic and statistical errors, and we illustrate it using three examples: the two-dimensional three-state Potts antiferromagnet on the square lattice, and the two-dimensional O(3) and O(?) ? models. In favorable cases it is possible to obtain reliable extrapolations (errors of a few percent) even when the correlation length is 1000 times larger than the lattice.

1995-01-01

127

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have determined the bulk melting temperature T[subscript m] of nickel according to a recent interatomic interaction model via Monte Carlo simulation by two methods: extrapolation from cluster melting temperatures based on the Pavlov model (a variant of the Gibbs-Thompson model) and by calculation...

Pellenq, Roland J. -M.; Los, J. H.

128

3D-Euler calculations using characteristic flux extrapolation

The characteristic-upwinding flux-extrapolation scheme developed by Eberle (1983 and 1984) for the numerical computation of solutions to the Euler equations is briefly characterized, and sample results are presented graphically. The technique requires no added artificial viscosity and only one grid sweep per iteration for the steady-state computation. The examples shown include the flow past an automobile, an ONERA M6 wing, a Dillner wing, an aircraft, and a Butler wing and demonstrate the promise of the technique in computations for low and high freestream Mach numbers, vortex flows, and unsteady flows.

Eberle, A.

1985-01-01

129

Chiral Extrapolation of the Strangeness Changing K \\pi Form Factor

We perform a chiral extrapolation of lattice data on the scalar $K \\pi$ form factor and the ratio of the kaon and pion decay constants within Chiral Perturbation Theory to two loops. We determine the value of the scalar form factor at zero momentum transfer, at the Callan-Treiman point and at its soft kaon analog as well as its slope. Results are in good agreement with their determination from experiment using the standard couplings of quarks to the W boson. The slope is however rather large. A study of the convergence of the chiral expansion is also performed.

Bernard, Veronique

2009-01-01

130

UK PubMed Central (United Kingdom)

We have implemented the sweep algorithm for the variational optimization of SU(2) U(1) (spin and particle number) invariant matrix product states (MPS) for general spin and particle number invariant fermionic Hamiltonians. This class includes non-relativistic quantum chemical systems within the Born-Oppenheimer approximation. High-accuracy ab initio finite field results of the longitudinal static polarizabilities and second hyperpolarizabilities of one-dimensional hydrogen chains are presented. This allows to assess the performance of other quantum chemical methods. For small basis sets, MPS calculations in the saturation regime of the optical response properties can be performed. These results are extrapolated to the thermodynamic limit.

Wouters S; Limacher PA; Van Neck D; Ayers PW

2012-04-01

131

We have implemented the sweep algorithm for the variational optimization of SU(2) x U(1) (spin and particle number) invariant matrix product states (MPS) for general spin and particle number invariant fermionic Hamiltonians. This class includes non-relativistic quantum chemical systems within the Born-Oppenheimer approximation. High-accuracy ab-initio finite field results of the longitudinal static polarizabilities and second hyperpolarizabilities of one-dimensional hydrogen chains are presented. This allows to assess the performance of other quantum chemical methods. For small basis sets, MPS calculations in the saturation regime of the optical response properties can be performed. These results are extrapolated to the thermodynamic limit.

Wouters, Sebastian; Van Neck, Dimitri; Ayers, Paul W

2012-01-01

132

We have implemented the sweep algorithm for the variational optimization of SU(2) ? U(1) (spin and particle number) invariant matrix product states (MPS) for general spin and particle number invariant fermionic Hamiltonians. This class includes non-relativistic quantum chemical systems within the Born-Oppenheimer approximation. High-accuracy ab initio finite field results of the longitudinal static polarizabilities and second hyperpolarizabilities of one-dimensional hydrogen chains are presented. This allows to assess the performance of other quantum chemical methods. For small basis sets, MPS calculations in the saturation regime of the optical response properties can be performed. These results are extrapolated to the thermodynamic limit.

Wouters, Sebastian; Limacher, Peter A.; Van Neck, Dimitri; Ayers, Paul W.

2012-04-01

133

Resolution enhancement in digital holography by self-extrapolation of holograms.

UK PubMed Central (United Kingdom)

It is generally believed that the resolution in digital holography is limited by the size of the captured holographic record. Here, we present a method to circumvent this limit by self-extrapolating experimental holograms beyond the area that is actually captured. This is done by first padding the surroundings of the hologram and then conducting an iterative reconstruction procedure. The wavefront beyond the experimentally detected area is thus retrieved and the hologram reconstruction shows enhanced resolution. To demonstrate the power of this concept, we apply it to simulated as well as experimental holograms.

Latychevskaia T; Fink HW

2013-03-01

134

Resolution enhancement in digital holography by self-extrapolation of holograms

It is generally believed that the resolution in digital holography is limited by the size of the captured holographic record. Here, we present a method to circumvent this limit by self-extrapolating experimental holograms beyond the area that is actually captured. This is done by first padding the surroundings of the hologram and then conducting an iterative reconstruction procedure. The wavefront beyond the experimentally detected area is thus retrieved and the hologram reconstruction shows enhanced resolution. To demonstrate the power of this concept, we apply it to simulated as well as experimental holograms.

Latychevskaia, Tatiana

2013-01-01

135

Resolution enhancement in digital holography by self-extrapolation of holograms.

It is generally believed that the resolution in digital holography is limited by the size of the captured holographic record. Here, we present a method to circumvent this limit by self-extrapolating experimental holograms beyond the area that is actually captured. This is done by first padding the surroundings of the hologram and then conducting an iterative reconstruction procedure. The wavefront beyond the experimentally detected area is thus retrieved and the hologram reconstruction shows enhanced resolution. To demonstrate the power of this concept, we apply it to simulated as well as experimental holograms. PMID:23546153

Latychevskaia, Tatiana; Fink, Hans-Werner

2013-03-25

136

International Nuclear Information System (INIS)

[en] In an earlier paper the critical size of the spheres and infinite slabs was calculated with a method by Garlvik for monoenergetic neutrons scattering anisotropically. From the results and from the work by Sanchez on the critical size of infinite cylinders, accurate extrapolation lengths have been derived for various dimensions and for an average cosine of the scattering angle up to 0.3. For not too thin slabs there is good agreement with an approximation formula derived by Davison. However, the formula is not applicable to spheres or cylinders in the presence of anisotropic scattering. (author)

1979-01-01

137

Coronal Magnetic Field Extrapolation from Photospheric Measurements Applied to an Active Region

We outline an MHD relaxation method that permits to extrapolate photospheric vector magnetograms into coronal nonlinear force-free fields. The method is applied to a magnetogram taken before an eruptive event in NOAA AR 7792 on 25 October 1994. The event produced a coronal mass ejection (CME) and eruptive flare with a prominent sigmoidal soft X-ray source. Multiwavelength observations as well as theoretical modeling indicate the importance of twisted magnetic configurations in solar active regions(ARs) in the initiation of such events. Manoharan et al. (1996) proposed a model for this event that included the merging of two slightly twisted flux bundles near the polarity inversion line into a flux rope of larger total twist and an overlying flux system much closer to a potential-field state. For the extrapolation we use a vector magnetogram taken at the Mees Solar Observatory 16 hours before the actual event. The magnetic field extrapolation is able to recover main parts of the structures suggested in the model by Manoharan et al. We find the overlying nearly potential flux and part of the sigmoidal field, i.e., one of the suggested weakly twisted flux bundles, in the location observed. This supports the notion that sigmoids are coronal manifestations of twisted magnetic flux tubes which start expanding in eruptive events and may exist even before the onset of such events. We tentatively attribute the incomplete reconstruction of the sigmoidal field structure to the strong evolution of the photospheric field at the suggested location of flux tube merging between the time of the magnetogram and the eruption, as indicated by a magnetogram on the following day.

Fuhrmann, M.; Kliem, B.; Valori, G.; Seehafer, N.

2008-09-01

138

Nowcasting of precipitation events, especially thunderstorm events or winter storms, has high impact on flight safety and efficiency for air traffic management. Future strategic planning by air traffic control will result in circumnavigation of potential hazardous areas, reduction of load around efficiency hot spots by offering alternatives, increase of handling capacity, anticipation of avoidance manoeuvres and increase of awareness before dangerous areas are entered by aircraft. To facilitate this rapid update forecasts of location, intensity, size, movement and development of local storms are necessary. Weather radar data deliver precipitation analysis of high temporal and spatial resolution close to real time by using clever scanning strategies. These data are the basis to generate rapid update forecasts in a time frame up to 2 hours and more for applications in aviation meteorological service provision, such as optimizing safety and economic impact in the context of sub-scale phenomena. On the basis of tracking radar echoes by correlation the movement vectors of successive weather radar images are calculated. For every new successive radar image a set of ensemble precipitation fields is collected by using different parameter sets like pattern match size, different time steps, filter methods and an implementation of history of tracking vectors and plausibility checks. This method considers the uncertainty in rain field displacement and different scales in time and space. By validating manually a set of case studies, the best verification method and skill score is defined and implemented into an online-verification scheme which calculates the optimized forecasts for different time steps and different areas by using different extrapolation ensemble members. To get information about the quality and reliability of the extrapolation process additional information of data quality (e.g. shielding in Alpine areas) is extrapolated and combined with an extrapolation-quality-index. Subsequently the probability and quality information of the forecast ensemble is available and flexible blending to numerical prediction model for each subarea is possible. Simultaneously with automatic processing the ensemble nowcasting product is visualized in a new innovative way which combines the intensity, probability and quality information for different subareas in one forecast image.

Kaltenboeck, Rudolf; Kerschbaum, Markus; Hennermann, Karin; Mayer, Stefan

2013-04-01

139

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

International Nuclear Information System (INIS)

[en] 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

1980-10-10

140

Sigma terms from an SU(3) chiral extrapolation

We report a new analysis of lattice simulation results for octet baryon masses in 2+1-flavor QCD, with an emphasis on a precise determination of the pion-nucleon and strangeness nucleon sigma terms. A controlled chiral extrapolation of a recent PACS-CS Collaboration data set yields baryon masses which exhibit remarkable agreement both with experimental values at the physical point and with the results of independent lattice QCD simulations at unphysical meson masses. Using the Feynman-Hellmann relation, we evaluate sigma commutators for all octet baryons. The small statistical uncertainty and considerably smaller model dependence allows a significantly more precise determination of the pion-nucleon sigma commutator and the strangeness sigma term than hitherto possible, subject to an unresolved issue concerning the lattice scale setting.

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

2013-04-01

141

UFOs in the LHC: Observations, studies and extrapolations

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

142

On the extrapolation to ITER of discharges in present tokamaks

An expression for the extrapolated fusion gain G = Pfusion /5 Pheat (Pfusion being the total fusion power and Pheat the total heating power) of ITER in terms of the confinement improvement factor (H) and the normalised beta (betaN) is derived in this paper. It is shown that an increase in normalised beta can be expected to have a negative or neutral influence on G depending on the chosen confinement scaling law. Figures of merit like H betaN / q95^2 should be used with care, since large values of this quantity do not guarantee high values of G, and might not be attainable with the heating power installed on ITER.

Peeters, A G; Sips, A C C

2007-01-01

143

Behavioral effects of carbon monoxide: Meta analyses and extrapolations

Energy Technology Data Exchange (ETDEWEB)

In the absence of reliable data, the present work was performed to estimate the dose effect function of carboxyhemoglobin (COHb) on behavior in humans. By meta analysis, a COHb-behavior dose-effects functions was estimated for rats and corrected for effects of hypothermia (which accompanies COHb increases in rats but not in humans). Using pulmonary function models and blood-gas equations, equivalent COHb values were calculated for data in the literature on hypoxic hypoxia (HH) and behavior. Another meta analysis was performed to fit a dose-effects function to the equivalent-COHb data and to correct for the behavioral effects of hypocapnia (which usually occurs during HH but not with COHb elevation). The two extrapolations agreed closely and indicated that for healthy, sedentary persons, it would require 18-25% COHb to produce a 10% decrement in behavior. Confidence intervals were computed to characterize the uncertainty. Frequent reports of lower-level effects were discussed.

Benignus, V.A.

1993-03-16

144

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

International Nuclear Information System (INIS)

[en] 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

1980-10-10

145

International Nuclear Information System (INIS)

We use rotation stereoscopy to estimate the height of a steady-state solar feature relative to the photosphere, based on its apparent motion in the image plane recorded over several days of observation. The stereoscopy algorithm is adapted to work with either one- or two-dimensional data (i.e., from images or from observations that record the projected position of the source along an arbitrary axis). The accuracy of the algorithm is tested on simulated data, and then the algorithm is used to estimate the coronal radio source heights associated with the active region NOAA 10956, based on multifrequency imaging data over seven days from the Siberian Solar Radio Telescope near 5.7 GHz, the Nobeyama Radio Heliograph at 17 GHz, as well as one-dimensional scans at multiple frequencies spanning the 5.98-15.95 GHz frequency range from the RATAN-600 instrument. The gyroresonance emission mechanism, which is sensitive to the coronal magnetic field strength, is applied to convert the estimated radio source heights at various frequencies, h(f), to information about magnetic field versus height B(h), and the results are compared to a magnetic field extrapolation derived from photospheric magnetic field observations obtained by Hinode and Michelson Doppler Imager. We found that the gyroresonant emission comes from heights exceeding the location of the third gyrolayer irrespective of the magnetic extrapolation method; implications of this finding for coronal magnetography and coronal plasma physics are discussed.

2011-08-20

146

UK PubMed Central (United Kingdom)

The first-principles calculation of non-covalent (particularly dispersion) interactions between molecules is a considerable challenge. In this work we studied the binding energies for ten small non-covalently bonded dimers with several combinations of correlation methods (MP2, coupled-cluster single double, coupled-cluster single double (triple) (CCSD(T))), correlation-consistent basis sets (aug-cc-pVXZ, X = D, T, Q), two-point complete basis set energy extrapolations, and counterpoise corrections. For this work, complete basis set results were estimated from averaged counterpoise and non-counterpoise-corrected CCSD(T) binding energies obtained from extrapolations with aug-cc-pVQZ and aug-cc-pVTZ basis sets. It is demonstrated that, in almost all cases, binding energies converge more rapidly to the basis set limit by averaging the counterpoise and non-counterpoise corrected values than by using either counterpoise or non-counterpoise methods alone. Examination of the effect of basis set size and electron correlation shows that the triples contribution to the CCSD(T) binding energies is fairly constant with the basis set size, with a slight underestimation with CCSD(T)?aug-cc-pVDZ compared to the value at the (estimated) complete basis set limit, and that contributions to the binding energies obtained by MP2 generally overestimate the analogous CCSD(T) contributions. Taking these factors together, we conclude that the binding energies for non-covalently bonded systems can be accurately determined using a composite method that combines CCSD(T)?aug-cc-pVDZ with energy corrections obtained using basis set extrapolated MP2 (utilizing aug-cc-pVQZ and aug-cc-pVTZ basis sets), if all of the components are obtained by averaging the counterpoise and non-counterpoise energies. With such an approach, binding energies for the set of ten dimers are predicted with a mean absolute deviation of 0.02 kcal/mol, a maximum absolute deviation of 0.05 kcal/mol, and a mean percent absolute deviation of only 1.7%, relative to the (estimated) complete basis set CCSD(T) results. Use of this composite approach to an additional set of eight dimers gave binding energies to within 1% of previously published high-level data. It is also shown that binding within parallel and parallel-crossed conformations of naphthalene dimer is predicted by the composite approach to be 9% greater than that previously reported in the literature. The ability of some recently developed dispersion-corrected density-functional theory methods to predict the binding energies of the set of ten small dimers was also examined.

Mackie ID; DiLabio GA

2011-10-01

147

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

International Nuclear Information System (INIS)

[en] 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)

2011-01-01

148

UK PubMed Central (United Kingdom)

Mathematical models of biological processes for the model yeast Saccharomyces cerevisiae are the subject of intensive effort and are available in increasing numbers. An open question is whether such models are informative for related yeasts of biotechnological and medical interest that will not themselves benefit from an equivalent effort. In this study, we assess a method for extrapolating reference models to other completely sequenced yeasts, using a combination of graph-theoretic analysis and reliable identification of homologous genes using Génolevures protein families. In this first assessment, we focus on subtractive modeling, identified through the correlated loss of input and output ports in metabolic pathways. We confirm that the major, highly connected, pathways of central metabolism are conserved and might be universal. In 60-80% of our results, further analysis is not required to determine whether the pathway is lost or conserved, so that our method can be systematically applied as a first step in developing species-specific models.

Iragne F; Nikolski M; Sherman D

2008-02-01

149

Mathematical models of biological processes for the model yeast Saccharomyces cerevisiae are the subject of intensive effort and are available in increasing numbers. An open question is whether such models are informative for related yeasts of biotechnological and medical interest that will not themselves benefit from an equivalent effort. In this study, we assess a method for extrapolating reference models to other completely sequenced yeasts, using a combination of graph-theoretic analysis and reliable identification of homologous genes using Génolevures protein families. In this first assessment, we focus on subtractive modeling, identified through the correlated loss of input and output ports in metabolic pathways. We confirm that the major, highly connected, pathways of central metabolism are conserved and might be universal. In 60-80% of our results, further analysis is not required to determine whether the pathway is lost or conserved, so that our method can be systematically applied as a first step in developing species-specific models. PMID:17714476

Iragne, Florian; Nikolski, Macha; Sherman, David

2007-08-22

150

Precise estimates by finite-size extrapolations of the S=1 Haldane-gapped system

Energy Technology Data Exchange (ETDEWEB)

We carry out finite-size extrapolations of numerical-diagonalization data of the S=1 Heisenberg chain having a nonzero energy gap between the unique singlet ground state and the first excited state, namely the Haldane gap. Very precise estimates of the ground-state energy per site E{sub g}/N -1.4014840447(39) and the staggered component of the magnetic structure factor S{sub {pi}} = 3.864356(31) at T=0 are successfully obtained from the finite-size data of system sizes up to N = 24 under the twisted boundary condition by the sequence interval squeeze method, which was applied to a precise estimation of the Haldane gap by Nakano and Terai [J. Phys. Soc. Jpn. 78 (2009) 014003]. The present estimates are compared with other estimates in previous studies from various methods including the quantum Monte Carlo simulation and the density matrix renormalization group calculation.

Nakano, Hiroki, E-mail: hnakano@sci.u-hyogo.ac.j [Graduate School of Material Science, University of Hyogo, Kouto, Kamigori, Ako 678-1297 (Japan)

2010-01-01

151

International Nuclear Information System (INIS)

An intercomparison of directional absorbed dose rates, D'(0.07,?), at radiation protection levels in beta dosimetry was performed by five European laboratories in 1993 and 1994 using extrapolation chambers. For this purpose, a 204Tl beta ray source with an activity of about 6 MBq, constituent of the PTB Beta Secondary Standard, was sent to the five laboratories for intercomparison measurements. The dose rates, without a beam flattening filter, were determined at a distance of 20 cm for angles of incidence of the radiation, ?, of 0o and 60o. In the first stage of the intercomparison some unexpected differences of up to ± 5% in the results were obtained. These could be explained by the different methods used by the participants for measuring depth-dose curves. After applying a consistent method, the results of all participants agreed to within ± 2%. (author).

1996-01-01

152

Characterization and extrapolation of a conceptual experimental accelerator driven system

International Nuclear Information System (INIS)

This paper deals with the neutronic Monte Carlo simulations in view of an eXperimental Accelerator Driven System (XADS) optimization and characterization. With this aim, the quite realistic concept of XADS chosen for our investigations, comes from the preliminary studies done by Framatome ANP. First, we simulate this basic concept with different fuels and characterize the time evolution of the conceivable fuels, especially with minor actinides. Secondly, we consider the neutronic parameters in view of an extrapolation of the XADS toward a large ADS. We also consider some alternative solutions to reduce the flux peak in the first assemblies around the spallation target of a large ADS and consequently to improve the shape factor and the efficiency of the core. Finally, we focus on the generation of 233U based on a plutonium and minor actinide fuel associated to thorium oxide to start power Molten Salt Reactors (MSR) and to accelerate the transition toward a 232Th/233U cycle which offers an interesting option for nuclear waste reduction and nuclear energy production during many centuries. (authors)

2001-01-01

153

Measurement of fatty acid oxidation: validation of isotopic equilibrium extrapolation

International Nuclear Information System (INIS)

[en] 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 diminished radioisotope exposure

1989-01-01

154

Adaptation to implied tilt: extensive spatial extrapolation of orientation gradients

To extract the global structure of an image, the visual system must integrate local orientation estimates across space. Progress is being made toward understanding this integration process, but very little is known about whether the presence of structure exerts a reciprocal influence on local orientation coding. We have previously shown that adaptation to patterns containing circular or radial structure induces tilt-aftereffects (TAEs), even in locations where the adapting pattern was occluded. These spatially “remote” TAEs have novel tuning properties and behave in a manner consistent with adaptation to the local orientation implied by the circular structure (but not physically present) at a given test location. Here, by manipulating the spatial distribution of local elements in noisy circular textures, we demonstrate that remote TAEs are driven by the extrapolation of orientation structure over remarkably large regions of visual space (more than 20°). We further show that these effects are not specific to adapting stimuli with polar orientation structure, but require a gradient of orientation change across space. Our results suggest that mechanisms of visual adaptation exploit orientation gradients to predict the local pattern content of unfilled regions of space.

Roach, Neil W.; Webb, Ben S.

2013-01-01

155

Adaptation to implied tilt: extensive spatial extrapolation of orientation gradients.

UK PubMed Central (United Kingdom)

To extract the global structure of an image, the visual system must integrate local orientation estimates across space. Progress is being made toward understanding this integration process, but very little is known about whether the presence of structure exerts a reciprocal influence on local orientation coding. We have previously shown that adaptation to patterns containing circular or radial structure induces tilt-aftereffects (TAEs), even in locations where the adapting pattern was occluded. These spatially "remote" TAEs have novel tuning properties and behave in a manner consistent with adaptation to the local orientation implied by the circular structure (but not physically present) at a given test location. Here, by manipulating the spatial distribution of local elements in noisy circular textures, we demonstrate that remote TAEs are driven by the extrapolation of orientation structure over remarkably large regions of visual space (more than 20°). We further show that these effects are not specific to adapting stimuli with polar orientation structure, but require a gradient of orientation change across space. Our results suggest that mechanisms of visual adaptation exploit orientation gradients to predict the local pattern content of unfilled regions of space.

Roach NW; Webb BS

2013-01-01

156

Rigorous absorbing boundary conditions for 3-D one-way wave extrapolation

Energy Technology Data Exchange (ETDEWEB)

Absorbing boundary conditions play in important role in one-way wave extrapolations by reducing reflection at grid edges. Clayton and Engquist's 2-D absorbing boundary conditions for one-way wave extrapolation by depth stepping in the frequency domain are extended to three dimensions using paraxial approximations of the scalar wave equation. Internal consistency is retained by incorporating the interior extrapolation equation with the absorbing boundary conditions. Numerical schemes are designed to make the proposed absorbing boundary conditions both mathematically correct and efficient with negligible extra cost. Synthetic examples illustrate the effectiveness of the algorithm for extrapolation with the 3-D 45{degree} one-way wave equation.

Zhou, H.; McMechan, G.A.

2000-04-01

157

Measurement of fatty acid oxidation: validation of isotopic equilibrium extrapolation

Energy Technology Data Exchange (ETDEWEB)

Measurement of whole body substrate oxidation requires prolonged isotope infusion to attain plateau specific activity (SA) of expired CO/sub 2/. We have investigated in 13 hospitalized patients a technique whereby plateau /sup 14/CO/sub 2/ SA is extrapolated using computer curve fitting based upon the early exponential rise. A primed-constant infusion of albumin-bound 1-/sup 14/C-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 /sup 14/CO/sub 2/ SA reached only 44% +/- 1% of the 190 to 260 minute values, which were consistently at plateau. The predicted steady state /sup 14/CO/sub 2/ 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 /sup 14/CO/sub 2/ 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 diminished radioisotope exposure.

Robin, A.P.; Jeevanandam, M.; Elwyn, D.H.; Askanazi, J.; Kinney, J.M.

1989-01-01

158

UK PubMed Central (United Kingdom)

Knowledge-based speech recognition systems extract acoustic cues from the signal to identify speech characteristics. For channel-deteriorated telephone speech, acoustic cues, especially those for stop consonant place, are expected to be degraded or absent. To investigate the use of knowledge-based methods in degraded environments, feature extrapolation of acoustic-phonetic features based on Gaussian mixture models is examined. This process is applied to a stop place detection module that uses burst release and vowel onset cues for consonant-vowel tokens of English. Results show that classification performance is enhanced in telephone channel-degraded speech, with extrapolated acoustic-phonetic features reaching or exceeding performance using estimated Mel-frequency cepstral coefficients (MFCCs). Results also show acoustic-phonetic features may be combined with MFCCs for best performance, suggesting these features provide information complementary to MFCCs.

Lee JW; Choi JY; Kang HG

2012-02-01

159

UK PubMed Central (United Kingdom)

The aim of this study was to propose an improved method for accurate dialysis dose evaluation and extrapolation by means of Kt/ V from online UV-absorbance measurements for real time and continuous treatment monitoring. The study included a total of 24 treatments from ten uremic patients, seven of whom were male and three females. All patients were on chronic thrice-weekly hemodialysis therapy. The study included both stable and unstable treatments. A known signal processing algorithm, Levenberg-Marquardt, and the newly developed SMART were utilized for the removal of disturbances not relevant for dialysis dose evaluation. Finally, the results were compared with the Kt/ V values based on the blood samples. The new data processing algorithm, SMART, removes disturbances, helps estimate the online Kt/ V with significant precision increase and without any time delay, and more effectively predicts the end Kt/ V for the treatment than the known algorithms.

Fridolin I; Karai D; Kostin S; Ubar R

2013-05-01

160

Energy Technology Data Exchange (ETDEWEB)

Ecological models of the seasonal exchange of carbon dioxide between the atmosphere and the terrestrial biosphere are needed in the study of changes in atmospheric CO/sub 2/ concentration. In response to this need, a set of site-specific models of seasonal terrestrial carbon dynamics was assembled from open-literature sources. The collection was chosen as a base for the development of biome-level models for each of the earth's principal terrestrial biomes or vegetation complexes. Two methods of extrapolation were tested. The first approach was a simple extrapolation that assumed relative within-biome homogeneity, and generated CO/sub 2/ source functions that differed dramatically from published estimates of CO/sub 2/ exchange. The differences were so great that the simple extrapolation was rejected as a means of incorporating site-specific models in a global CO/sub 2/ source function. The second extrapolation explicitly incorporated within-biome variability in the abiotic variables that drive seasonal biosphere-atmosphere CO/sub 2/ exchange. Simulated site-specific CO/sub 2/ dynamics were treated as a function of multiple random variables. The predicated regional CO/sub 2/ exchange is the computed expected value of simulated site-specific exchanges for that region times the area of the region. The test involved the regional extrapolation of tundra and a coniferous forest carbon exchange model. Comparisons between the CO/sub 2/ exchange estimated by extrapolation and published estimates of regional exchange for the latitude belt support the appropriateness of extrapolation by expected value.

King, A.W.

1986-01-01

161

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

Energy Technology Data Exchange (ETDEWEB)

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 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.

Sadeghi Naini, Ali; Pierce, Greg; Lee, Ting-Yim [Department of Electrical and Computer Engineering, University of Western Ontario, London, Ontario N6A 5B9 (Canada); and others

2011-02-15

162

Energy Technology Data Exchange (ETDEWEB)

Considerable doubt surrounds the nature of processes by which {sup 137}Cs is deposited in marine sediments, leading to a situation where {sup 137}Cs geochronology cannot be always applied suitably. Based on extrapolation with Weibull distribution, the maximum concentration of {sup 137}Cs derived from asymptotic values for cumulative specific inventory was used to re-establish {sup 137}Cs geochronology, instead of original {sup 137}Cs profiles. Corresponding dating results for cores in Tokyo Bay and Ise Bay, Japan, by means of this new method, are in much closer agreement with those calculated from {sup 210}Pb method than the previous method.

Lu Xueqiang E-mail: xueqianglu@yahoo.com

2004-07-01

163

Due to the absence of direct measurement, the magnetic field in the solar corona is usually extrapolated from the photosphere in 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 \\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 importa...

Jiang, Chaowei

2013-01-01

164

A new mini-extrapolation chamber for beta source uniformity measurements

Energy Technology Data Exchange (ETDEWEB)

According to recent international recommendations, beta particle sources should be specified in terms of absorbed dose rates to water at the reference point. However, because of the clinical use of these sources, additional information should be supplied in the calibration reports. This additional information include the source uniformity. A new small volume extrapolation chamber was designed and constructed at the Calibration Laboratory at Instituto de Pesquisas Energeticas e Nucleares, IPEN, Brazil, for the calibration of {sup 90}Sr+{sup 90}Y ophthalmic plaques. This chamber can be used as a primary standard for the calibration of this type of source. Recent additional studies showed the feasibility of the utilization of this chamber to perform source uniformity measurements. Because of the small effective electrode area, it is possible to perform independent measurements by varying the chamber position by small steps. The aim of the present work was to study the uniformity of a {sup 90}Sr+{sup 90}Y plane ophthalmic plaque utilizing the mini extrapolation chamber developed at IPEN. The uniformity measurements were performed by varying the chamber position by steps of 2 mm in the source central axis (x-and y-directions) and by varying the chamber position off-axis by 3 mm steps. The results obtained showed that this small volume chamber can be used for this purpose with a great advantage: it is a direct method, being unnecessary a previously calibration of the measurement device in relation to a reference instrument, and it provides real -time results, reducing the time necessary for the study and the determination of the uncertainties related to the measurements. (authors)

Oliveira, M.L. [Centro Regional de Ciencias Nucleares, CRCN/CNEN, Recife (Brazil); Caldas, L.V.E. [Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN, Sao Paulo (Brazil)

2006-07-01

165

Directory of Open Access Journals (Sweden)

Full Text Available Background: There are many different methods for the assessment of whole blood viscosity, but not every pathology unit has equipment for any of the methods. However, a validated arithmetic method exists whereby whole blood viscosity can be extrapolated from haematocrit and total serum proteins. Aims: The objective of this work is to develop an algorithm in the form of a chart by which clinicians can easily extrapolate whole blood viscosity values in their consulting rooms or on the ward. Another objective is to suggest normal, subnormal and critical reference ranges applicable to this method. Materials and Methods: Whole blood viscosity at high shear stress was determined, from various possible pairs of haematocrit and total proteins. A chart was formulated so that whole blood viscosity can be extrapolated. After determination of two standard deviations from the mean and ascertainment of symmetric distribution, normal and abnormal reference ranges were defined. Results: The clinicians’ user-friendly chart is presented. Considering presumptive lower and upper limits, the continuum of ?14.28, 14.29 – 15.00, 15.01 – 19.01, 19.02 – 19.39 and ?19.40 (208 Sec-1) is obtained as reference ranges for critically low, subnormal low, normal, subnormal high and critically high whole blood viscosity levels respectively. Conclusion: This article advances a validated method to provide a user-friendly chart that would enable clinicians to assess whole blood viscosity for any patients who has results for full blood count and total proteins. It would make the assessment of whole blood viscosity costless and the neglect of a known cardiovascular risk factor less excusable.

Ezekiel Uba Nwose

2010-01-01

166

International Nuclear Information System (INIS)

[en] Highlights: ? The DPE method predicts temperature and density profiles in a fusion reactor. ? This method is based on the gyro-Bohm type parameter dependence. ? The size of fusion reactor is determined to fulfill the power balance. ? The reactor size is proportional to a factor and ?4/3 power of the magnetic field. ? 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, Cexp, 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 Cexp 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.

2011-01-01

167

International Nuclear Information System (INIS)

[en] 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)

1995-01-01

168

In this paper, we apply Aitken extrapolation and epsilon algorithm as acceleration technique for the solution of a weakly singular nonlinear Volterra integral equation of the second kind. In this paper, based on Tao and Yong (2006 J. Math. Anal. Appl. 324 225-37.) the integral equation is solved by Navot's quadrature formula. Also, Tao and Yong (2006) for the first time applied Richardson extrapolation to accelerating convergence for the weakly singular nonlinear Volterra integral equations of the second kind. To our knowledge, this paper may be the first attempt to apply Aitken extrapolation and epsilon algorithm for the weakly singular nonlinear Volterra integral equations of the second kind.

Mesgarani, H.; Aghazadeh, N.; Parmour, P.

2010-02-01

169

International Nuclear Information System (INIS)

In this paper, we apply Aitken extrapolation and epsilon algorithm as acceleration technique for the solution of a weakly singular nonlinear Volterra integral equation of the second kind. In this paper, based on Tao and Yong (2006 J. Math. Anal. Appl. 324 225-37.) the integral equation is solved by Navot's quadrature formula. Also, Tao and Yong (2006) for the first time applied Richardson extrapolation to accelerating convergence for the weakly singular nonlinear Volterra integral equations of the second kind. To our knowledge, this paper may be the first attempt to apply Aitken extrapolation and epsilon algorithm for the weakly singular nonlinear Volterra integral equations of the second kind.

2010-01-01

170

Energy Technology Data Exchange (ETDEWEB)

In this paper, we apply Aitken extrapolation and epsilon algorithm as acceleration technique for the solution of a weakly singular nonlinear Volterra integral equation of the second kind. In this paper, based on Tao and Yong (2006 J. Math. Anal. Appl. 324 225-37.) the integral equation is solved by Navot's quadrature formula. Also, Tao and Yong (2006) for the first time applied Richardson extrapolation to accelerating convergence for the weakly singular nonlinear Volterra integral equations of the second kind. To our knowledge, this paper may be the first attempt to apply Aitken extrapolation and epsilon algorithm for the weakly singular nonlinear Volterra integral equations of the second kind.

Mesgarani, H; Parmour, P [Department of Mathematics, Shahid Rajaee University, Lavizan, Tehran (Iran, Islamic Republic of); Aghazadeh, N [Department of Applied Mathematics, Azarbaijan University of Tarbiat Moallem, Tabriz 53751 71379 (Iran, Islamic Republic of)], E-mail: hmesgarani@sru.ac.ir, E-mail: pparmour@yahoo.com, E-mail: aghazadeh@azaruniv.edu

2010-02-15

171

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.

2010-05-20

172

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

Energy confinement scaling and the extrapolation to ITER

International Nuclear Information System (INIS)

The fusion performance of ITER is predicted using three different techniques; statistical analysis of the global energy confinement data, a dimensionless physics parameter similarity method and the full 1-D modeling of the plasma profiles. Although the three methods give overlapping predictions for the performance of ITER, the confidence interval of all of the techniques is still quite wide.

1997-01-01

174

Energy confinement scaling and the extrapolation to ITER

Energy Technology Data Exchange (ETDEWEB)

The fusion performance of ITER is predicted using three different techniques; statistical analysis of the global energy confinement data, a dimensionless physics parameter similarity method and the full 1-D modeling of the plasma profiles. Although the three methods give overlapping predictions for the performance of ITER, the confidence interval of all of the techniques is still quite wide.

NONE

1997-11-01

175

Loop integration results using numerical extrapolation for a non-scalar integral

Energy Technology Data Exchange (ETDEWEB)

Loop integration results have been obtained using numerical integration and extrapolation. An extrapolation to the limit is performed with respect to a parameter in the integrand which tends to zero. Results are given for a non-scalar four-point diagram. Extensions to accommodate loop integration by existing integration packages are also discussed. These include: using previously generated partitions of the domain and roundoff error guards.

Doncker, E. de [Department of Computer Science, Western Michigan University, Kalamazoo, MI 49008 (United States)]. E-mail: elise@cs.wmich.edu; Shimizu, Y. [High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305 (Japan); Fujimoto, J. [High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305 (Japan)]. E-mail: junpei@suchi.kek.jp; Yuasa, F. [High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305 (Japan); Kaugars, K. [Department of Computer Science, Western Michigan University, Kalamazoo, MI 49008 (United States); Cucos, L. [Department of Computer Science, Western Michigan University, Kalamazoo, MI 49008 (United States); Van Voorst, J. [Department of Computer Science, Western Michigan University, Kalamazoo, MI 49008 (United States)

2004-11-21

176

Loop integration results using numerical extrapolation for a non-scalar integral

International Nuclear Information System (INIS)

[en] Loop integration results have been obtained using numerical integration and extrapolation. An extrapolation to the limit is performed with respect to a parameter in the integrand which tends to zero. Results are given for a non-scalar four-point diagram. Extensions to accommodate loop integration by existing integration packages are also discussed. These include: using previously generated partitions of the domain and roundoff error guards

2004-11-21

177

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

UK PubMed Central (United Kingdom)

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.

Fillard P; Arsigny V; Pennec X; Thompson PM; Ayache N

2005-01-01

178

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

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

179

Estimation and extrapolation of optimal treatment and testing strategies.

We review recent developments in the estimation of an optimal treatment strategy or regime from longitudinal data collected in an observational study. We also propose novel methods for using the data obtained from an observational database in one health-care system to determine the optimal treatment regime for biologically similar subjects in a second health-care system when, for cultural, logistical, or financial reasons, the two health-care systems differ (and will continue to differ) in the frequency of, and reasons for, both laboratory tests and physician visits. Finally, we propose a novel method for estimating the optimal timing of expensive and/or painful diagnostic or prognostic tests. Diagnostic or prognostic tests are only useful in so far as they help a physician to determine the optimal dosing strategy, by providing information on both the current health state and the prognosis of a patient because, in contrast to drug therapies, these tests have no direct causal effect on disease progression. Our new method explicitly incorporates this no direct effect restriction. PMID:18646286

Robins, James; Orellana, Liliana; Rotnitzky, Andrea

2008-10-15

180

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 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

1473-01-00

181

Energy Technology Data Exchange (ETDEWEB)

Ecological models of the seasonal exchange of carbon dioxide (CO/sub 2/) between the atmosphere and the terrestrial biosphere are needed in the study of changes in atmospheric CO/sub 2/ concentration. In response to this need, a set of site-specific models of seasonal terrestrial carbon dynamics was assembled from open-literature sources. The collection was chosen as a base for the development of biome-level models for each of the earth's principal terrestrial biomes or vegetation complexes. The primary disadvantage of this approach is the problem of extrapolating the site-specific models across large regions having considerable biotic, climatic, and edaphic heterogeneity. Two methods of extrapolation were tested. The first approach was a simple extrapolation that assumed relative within-biome homogeneity, and generated CO/sub 2/ source functions that differed dramatically from published estimates of CO/sub 2/ exchange. The second extrapolation explicitly incorporated within-biome variability in the abiotic variables that drive seasonal biosphere-atmosphere CO/sub 2/ exchange.

King, A.W.

1986-01-01

182

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

183

The hippocampus extrapolates beyond the view in scenes: An fMRI study of boundary extension.

Boundary extension (BE) is a pervasive phenomenon whereby people remember seeing more of a scene than was present in the physical input, because they extrapolate beyond the borders of the original stimulus. This automatic embedding of a scene into a wider context supports our experience of a continuous and coherent world, and is therefore highly adaptive. BE, whilst occurring rapidly, is nevertheless thought to comprise two stages. The first involves the active extrapolation of the scene beyond its physical boundaries, and is constructive in nature. The second phase occurs at retrieval, where the initial extrapolation beyond the original scene borders is revealed by a subsequent memory error. The brain regions associated with the initial, and crucial, extrapolation of a scene beyond the view have never been investigated. Here, using functional MRI (fMRI) and a classic BE paradigm, we found that this extrapolation of scenes occurred rapidly around the time a scene was first viewed, and was associated with engagement of the hippocampus (HC) and parahippocampal cortex (PHC). Using connectivity analyses we determined that the HC in particular seemed to drive the BE effect, exerting top-down influence on PHC and indeed as far back down the processing stream as early visual cortex (VC). These cortical regions subsequently displayed activity profiles that tracked the trial-by-trial subjective perception of the scenes, rather than physical reality, thereby reflecting the behavioural expression of the BE error. Together our results show that the HC is involved in the active extrapolation of scenes beyond their physical borders. This information is then automatically and rapidly channelled through the scene processing hierarchy as far back as early VC. This suggests that the anticipation and construction of scenes is a pervasive and important aspect of our online perception, with the HC playing a central role. PMID:23276398

Chadwick, Martin J; Mullally, Sinéad L; Maguire, Eleanor A

2012-11-29

184

The hippocampus extrapolates beyond the view in scenes: An fMRI study of boundary extension.

UK PubMed Central (United Kingdom)

Boundary extension (BE) is a pervasive phenomenon whereby people remember seeing more of a scene than was present in the physical input, because they extrapolate beyond the borders of the original stimulus. This automatic embedding of a scene into a wider context supports our experience of a continuous and coherent world, and is therefore highly adaptive. BE, whilst occurring rapidly, is nevertheless thought to comprise two stages. The first involves the active extrapolation of the scene beyond its physical boundaries, and is constructive in nature. The second phase occurs at retrieval, where the initial extrapolation beyond the original scene borders is revealed by a subsequent memory error. The brain regions associated with the initial, and crucial, extrapolation of a scene beyond the view have never been investigated. Here, using functional MRI (fMRI) and a classic BE paradigm, we found that this extrapolation of scenes occurred rapidly around the time a scene was first viewed, and was associated with engagement of the hippocampus (HC) and parahippocampal cortex (PHC). Using connectivity analyses we determined that the HC in particular seemed to drive the BE effect, exerting top-down influence on PHC and indeed as far back down the processing stream as early visual cortex (VC). These cortical regions subsequently displayed activity profiles that tracked the trial-by-trial subjective perception of the scenes, rather than physical reality, thereby reflecting the behavioural expression of the BE error. Together our results show that the HC is involved in the active extrapolation of scenes beyond their physical borders. This information is then automatically and rapidly channelled through the scene processing hierarchy as far back as early VC. This suggests that the anticipation and construction of scenes is a pervasive and important aspect of our online perception, with the HC playing a central role.

Chadwick MJ; Mullally SL; Maguire EA

2013-09-01

185

Measuring brain variability by extrapolating sparse tensor fields measured on sulcal lines.

UK PubMed Central (United Kingdom)

Modeling and understanding the variability of brain structures is a fundamental problem in neurosciences. Improved mathematical representations of structural brain variation are needed to help detect and understand genetic or disease related sources of abnormality, as well as to improve statistical power when integrating functional brain mapping data across subjects. In this paper, we develop a new mathematical model of normal brain variation based on a large set of cortical sulcal landmarks (72 per brain) delineated in each of 98 healthy human subjects scanned with 3D MRI (age: 51.8+/-6.2 years). We propose an original method to compute an average representation of the sulcal curves, which constitutes the mean anatomy. After affine alignment of the individual data across subjects, the second order moment distribution of the sulcal position 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 partial differential equations (PDEs) to tensor fields. As a result, we obtain a dense 3D variability map that agrees well with prior results on smaller subject samples. Moreover, "leave one (sulcus) out" tests show that our model is globally able to recover the missing information on brain variation when there is a consistent neighboring pattern of variability. Finally, we propose an innovative method to analyze the asymmetry of brain variability. As expected, the greatest asymmetries are found in regions that includes the primary language areas. Interestingly, any such asymmetries in anatomical variance, if it remains after anatomical normalization, could explain why there may be greater power to detect group activation in one hemisphere versus the other in fMRI studies.

Fillard P; Arsigny V; Pennec X; Hayashi KM; Thompson PM; Ayache N

2007-01-01

186

Measuring brain variability by extrapolating sparse tensor fields measured on sulcal lines.

Modeling and understanding the variability of brain structures is a fundamental problem in neurosciences. Improved mathematical representations of structural brain variation are needed to help detect and understand genetic or disease related sources of abnormality, as well as to improve statistical power when integrating functional brain mapping data across subjects. In this paper, we develop a new mathematical model of normal brain variation based on a large set of cortical sulcal landmarks (72 per brain) delineated in each of 98 healthy human subjects scanned with 3D MRI (age: 51.8+/-6.2 years). We propose an original method to compute an average representation of the sulcal curves, which constitutes the mean anatomy. After affine alignment of the individual data across subjects, the second order moment distribution of the sulcal position 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 partial differential equations (PDEs) to tensor fields. As a result, we obtain a dense 3D variability map that agrees well with prior results on smaller subject samples. Moreover, "leave one (sulcus) out" tests show that our model is globally able to recover the missing information on brain variation when there is a consistent neighboring pattern of variability. Finally, we propose an innovative method to analyze the asymmetry of brain variability. As expected, the greatest asymmetries are found in regions that includes the primary language areas. Interestingly, any such asymmetries in anatomical variance, if it remains after anatomical normalization, could explain why there may be greater power to detect group activation in one hemisphere versus the other in fMRI studies. PMID:17113311

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

2006-11-17

187

International Nuclear Information System (INIS)

[en] A recent study by Ahmed, Peterka, and Suits [J. Chem. Phys. 110, 4248 (1999)] has presented the first experimentally derived estimate of the singlet-triplet gap in the simplest alkyne, acetylene. Their value, T0(a(tilde sign) 3B2)=28 900 cm-1, does not agree with previous theoretical predictions using the coupled-cluster singles, doubles, and perturbative triples [CCSD(T)] method and a triple-? plus double polarization plus f-function basis set (TZ2P f ), which yields 30 500±1000 cm-1. This discrepancy has prompted us to investigate possible deficiencies in this usually-accurate theoretical approach. Employing extrapolations to the complete basis set limit along with corrections for full connected triple excitations, core correlation, and even relativistic effects, we obtain a value of 30 900 cm-1 (estimated uncertainty ±230 cm-1), demonstrating that the experimental value is underestimated. To assist in the interpretation of anticipated future experiments, we also present highly accurate excitation energies for the other three low-lying triplet states of acetylene, a(tilde sign) 3Bu(33 570±230 cm-1), b(tilde sign) 3Au(36 040±260 cm-1), and b(tilde sign) 3A2(38 380±260 cm-1), and the three lowest-lying states of vinylidene, X(tilde sign) 1A1(15 150±230 cm-1), a(tilde sign) 3B2(31 870±230 cm-1), and b(tilde sign) 3A2(36 840±350 cm-1). Finally, we assess the ability of density functional theory (DFT) and the Gaussian-3 method to match our benchmark results for adiabatic excitation energies of C2H2. (c) 2000 American Institute of Physics

2000-07-22

188

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).

1988-01-01

189

UK PubMed Central (United Kingdom)

Data on acute lethal inhalation toxicity from animal studies are commonly required for assessing the hazards to human health of volatile, gaseous and dusty chemicals or their mixtures. The International Maritime Organisation (IMO) made the provision of acute inhalation toxicity data a mandatory requirement for the carriage of bulk liquid chemicals transported by sea in tank ships, thereby creating the need for inhalation data on many hundreds of chemicals in bulk maritime transport. Taking note of previously published proposals for estimating acute inhalation toxicity hazards for chemicals, and the paucity of measured experimental data, an extrapolation method has been developed by the Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) to partly fulfil this need. This method should be seen as a pragmatic approach to the challenge of missing measured experimental test data, with the added benefit of reducing tests in experimental animals. The method is based on a route-to-route (i.e. between-route) extrapolation of information on acute oral and/or dermal toxicity, in combination with data on the potential for irritation and/or corrosion to skin and eyes. The validation of this method was based on the individual evaluation of inhalation toxicity studies for 330 chemicals, including mixtures and many important chemical groups, for which the IMO holds public and industry-confidential data. The authors contend that this extrapolation method offers a reliable basis for hazard evaluation in the context of bulk maritime transport, and the 'GESAMP inhalation toxicity extrapolation method' has become part of the IMO regulatory system for the carriage of bulk liquids (i.e. noxious liquid substances) on board tank ships.

Höfer T; James D; Syversen T; Bowmer T

2011-12-01

190

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

Energy Technology Data Exchange (ETDEWEB)

Accelerated aging tests play an important role in assessing the lifetime of manufactured products. There are two basic approaches to lifetime qualification. One tests a product to failure over range of accelerated conditions to calibrate a model, which is then used to calculate the failure time for conditions of use. A second approach is to test a component to a lifetime-equivalent dose (thermal or radiation) to see if it still functions to specification. Both methods have their advantages and limitations. A disadvantage of the 2nd method is that one does not know how close one is to incipient failure. This limitation can be mitigated by testing to some higher level of dose as a safety margin, but having a predictive model of failure via the 1st approach provides an additional measure of confidence. Even so, proper calibration of a failure model is non-trivial, and the extrapolated failure predictions are only as good as the model and the quality of the calibration. This paper outlines results for predicting the potential failure point of a system involving a mixture of two energetic materials, HMX (nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) and CP (2-(5-cyanotetrazalato) pentaammine cobalt (III) perchlorate). Global chemical kinetic models for the two materials individually and as a mixture are developed and calibrated from a variety of experiments. These include traditional thermal analysis experiments run on time scales from hours to a couple days, detonator aging experiments with exposures up to 50 months, and sealed-tube aging experiments for up to 5 years. 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; Adrzejewski, W J

2006-09-11

191

Energy Technology Data Exchange (ETDEWEB)

In radiated emission (RE) tests on an open area test site (OATS), measurements are often made at distances other than that relevant to the specification limit. In this case, the measured value is converted to the limit distance using a simple 1/{gamma} extrapolation. However, this extrapolation is not accurate because waves reflected from the metal ground plane are present on an OATS. In this paper, we have considered the extrapolation errors using a spherical dipole radiator (SDR) by experimental and theoretical works. The theoretical extrapolation factor is determined by the analytical solution of the SDR. The field strengths at 3 m and 10 m distances have been measured to obtain experimental extrapolation factors. The results show that the 1/{gamma} extrapolation introduces measurement uncertainty of -4.86 {approx} +0.44 dB for horizontal polarization and -9.16 {approx} -0.06 dB for vertical polarization. (author). 8 refs., 6 figs.

Kang, T.W.; Chung, W.C.; Kim, B.W.; Won, S.H. [Korea Research Institute of Standard and Science, Taejon (Korea); Kim, H.T. [Pohang University of Science and Technology, Pohang (Korea)

1999-08-01

192

Energy Technology Data Exchange (ETDEWEB)

An intercomparison of directional absorbed dose rates, D`(0.07,{alpha}), at radiation protection levels in beta dosimetry was performed by five European laboratories in 1993 and 1994 using extrapolation chambers. For this purpose, a {sup 204}Tl beta ray source with an activity of about 6 MBq, constituent of the PTB Beta Secondary Standard, was sent to the five laboratories for intercomparison measurements. The dose rates, without a beam flattening filter, were determined at a distance of 20 cm for angles of incidence of the radiation, {alpha}, of 0{sup o} and 60{sup o}. In the first stage of the intercomparison some unexpected differences of up to {+-} 5% in the results were obtained. These could be explained by the different methods used by the participants for measuring depth-dose curves. After applying a consistent method, the results of all participants agreed to within {+-} 2%. (author).

Helmstaedter, K.; Boehm, J. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Chartier, J.-L.; Cutarella, D. [CEA Centre d`Etudes Nucleaires de Fontenay-aux-Roses, 92 (France); Chauvenet, B.; Lecante, C. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France); Christensen, P. [Risoe National Lab., Roskilde (Denmark); Francis, T.M. [National Radiological Protection Board, Chilton (United Kingdom)

1996-08-01

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.)

2008-01-01

194

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

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

195

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

196

UK PubMed Central (United Kingdom)

Simple modifications of complete basis set extrapolation formulas chosen from the literature are examined with respect to their abilities to reproduce a diverse set of 183 reference atomization energies derived primarily from very large basis set standard, frozen core coupled-cluster singles, doubles plus perturbative triples (CCSD(T)) with the aug-cc-pVnZ basis sets. This reference set was augmented with a few larger chemical systems treated with explicitly correlated CCSD(T)-F12b using a quadruple zeta quality basis set followed by extrapolation to complete basis set limit. Tuning the extrapolation formula parameters for the present reference set resulted in substantial reductions in the error metrics. In the case of the best performing approach, the aVnZ extrapolated results are equivalent to or better than results obtained from raw aV(n + 3)Z basis set calculations. To the extent this behavior holds for molecules outside the reference set, it represents an improvement of at least one basis set level over the original formulations and a further significant reduction in the amount of computer time needed to accurately approximate the basis set limit.

Feller D

2013-02-01

197

International Nuclear Information System (INIS)

[en] The absorbed dose for equivalent soft tissue is determined,it is imparted by ophthalmologic applicators, (90 Sr/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)

1992-01-01

198

Photon neutrino-production in a chiral EFT for nuclei and extrapolation to $E_{\

We carry out a series of studies on pion and photon productions in neutrino/electron/photon--nucleus scatterings. The low energy region is investigated by using a chiral effective field theory for nuclei. The results for the neutral current induced photon production ($\\gamma$-NCP) are then extrapolated to neutrino energy $E_{\

Zhang, Xilin

2013-01-01

199

Potential Hydraulic Modelling Errors Associated with Rheological Data Extrapolation in Laminar Flow

Energy Technology Data Exchange (ETDEWEB)

The potential errors associated with the modelling of flows of non-Newtonian slurries through pipes, due to inadequate rheological models and extrapolation outside of the ranges of data bases, are demonstrated. The behaviors of both dilatant and pseudoplastic fluids with yield stresses, and the errors associated with treating them as Bingham plastics, are investigated.

Shadday, Martin A., Jr.

1997-03-20

200

International Nuclear Information System (INIS)

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

1994-01-01

201

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper we integrate heterogeneous inflation expectations into a simple monetary model. Guided by empirical evidence we assume that boundedly rational agents, selecting between extrapolative and regressive forecasting rules to predict the future inflation rate, prefer rules that have produced ...

Lines, Marji; Westerhoff, Frank

202

Slow Neutron Flux Extrapolation Distances in R-5 and Cirus Reactors.

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...

Kanchi S S. Sankaranarayanan N. Veeraraghavan

1976-01-01

203

Extrapolation and sharp norm estimates for classical operators on weighted Lebesgue spaces

Digital Repository Infrastructure Vision for European Research (DRIVER)

We obtain sharp weighted Lp estimates in the Rubio de Francia extrapolation theorem in terms of the Ap characteristic constant of the weight. Precisely, if for a given 1 < r < [infinity] the norm of a sublinear operator on Lr(w) is bounded by a function of the Ar characteristic...

Dragicevic, Oliver

204

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)

1975-01-01

205

Energy Technology Data Exchange (ETDEWEB)

Ecological models of the seasonal exchange of carbon dioxide (CO/sub 2/) between the atmosphere and the terrestrial biosphere are needed in the study of changes in atmospheric CO/sub 2/ concentration. In response to this need, a set of site-specific models of seasonal terrestrial carbon dynamics was assembled from open-literature sources. The collection was chosen as a base for the development of biome-level models for each of the earth's principal terrestrial biomes or vegetation complexes. The primary disadvantage of this approach is the problem of extrapolating the site-specific models across large regions having considerable biotic, climatic, and edaphic heterogeneity. Two methods of extrapolation were tested. 142 refs., 59 figs., 47 tabs

King, A.W.; DeAngelis, D.L.; Post, W.M.

1987-12-01

206

Extrapolation modeling of aerosol deposition in human and laboratory rat lungs

Energy Technology Data Exchange (ETDEWEB)

Laboratory test animals are often used as surrogates in exposure studies to assess the potential threat to human health following inhalation of airborne contaminants. To aid in the interpretation and extrapolation of data to man, dosimetric considerations need to be addressed. Therefore, a mathematical model describing the behavior and fate of inhaled particulate matter within the respiratory tracts of man and rats has been developed. In the computer simulations, the CO2 concentrations of inhalation exposure chamber atmospheres are controlled to produce desired breathing patterns in the rat which mimic human breathing patterns as functions of physical activity levels. Herein, deposition patterns in human and rat lung airways are specifically examined as functions of respiratory intensities and particle parameters. The model provides a basis for the re-evaluation of data from past experiments, and, perhaps most importantly, permits new inhalation exposure tests to be designed and conducted in a sound scientific manner regarding this endpoint: the extrapolation of results to human conditions.

Martonen, T.B.; Zhang, Z.; Yang, Y.

1992-01-01

207

Extrapolation of Nystrom solution for two dimensional nonlinear Fredholm integral equations

In this paper, we analyze the existence of asymptotic error expansion of the Nystrom solution for two-dimensional nonlinear Fredholm integral equations of the second kind. We show that the Nystrom solution admits an error expansion in powers of the step-size h and the step-size k. For a special choice of the numerical quadrature, the leading terms in the error expansion for the Nystrom solution contain only even powers of h and k, beginning with terms h2p and k2q. These expansions are useful for the application of Richardson extrapolation and for obtaining sharper error bounds. Numerical examples show that how Richardson extrapolation gives a remarkable increase of precision, in addition to faster convergence.

Guoqiang, Han; Jiong, Wang

2001-09-01

208

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

International Nuclear Information System (INIS)

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 125ISPGP biokinetic data were treated by MIRD formalism to perform Internal Dosimetry studies. Absorbed doses due to the 131I-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 131I were considered. (author)

2009-10-02

209

Boundary Conditions and Source Term for the One-Way Acoustic Depth Extrapolation

UK PubMed Central (United Kingdom)

The understanding of the source term in the one way equation is essential ifone wishes to use this equation for modeling seismic reflection data. A carefulintroduction of the source term and of the surface boundary condition in the oneway wave equations allow to recover with accuracy, using depth extrapolation, asynthetic field generated using the (two way) acoustic wave equation and initialtime conditions.1 IntroductionOne-way depth extrapolation is widely used in many seismic imaging techniques, in particularin migration (Claerbout, 1985; Berkhout, 1985; Stolt and Benson, 1986). In modelingof a seismic reflection experiment, sources and surface conditions are usually introducedin an ad hoc way. For instance, the source term is represented as a boundarycondition and boundary conditions are replaced by an approximation undertaking onlyupgoing energy. These approximations are due to the fact that the one-way wave equationsare either derived without a source term, or bounda...

Marwan Charara; Albert Tarantola

210

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

UK PubMed Central (United Kingdom)

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.

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

2010-10-01

211

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

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

212

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)

2009-10-02

213

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

Energy Technology Data Exchange (ETDEWEB)

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.

Hellesen, C.; Andersson Sunden, E.; Conroy, S.; Ericsson, G.; Eriksson, J.; Gatu Johnson, M.; Weiszflog, M. [Astronomy, EURATOM-VR, Uppsala University, Box 516, Uppsala 75120 (Sweden); Collaboration: JET-EFDA Contributors

2010-10-15

214

UK PubMed Central (United Kingdom)

I thank Dr. Atallah et al. for their comments (1) on our article regarding "universally achievable" techniques for cesarean hysterectomy for placenta previa accreta (2). They criticize that "Matsubara et al. have "extrapolated the cesarean hysterectomy from standard hysterectomy". I agree with this; however, I intentionally did it. The "extrapolatability" is what we wish to point out. This article is protected by copyright. All rights reserved.

Matsubara S

2013-08-01

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.

1989-01-01

216

When hadrons become unstable: a novel type of non-analyticity in chiral extrapolations

Hadron masses show a specific dependence on the quark masses. Therefore, the variation of these masses can cause a resonance in a hadronic scattering amplitude to become a bound state. Consequently, the amplitude exhibits a non-analytic behavior at this transition. Crossed amplitudes, where the resonance can be exchanged in the t-channel, can be shown to exhibit the same phenomenon by s-->t analytic continuation. This entails possible kinks in lattice quark mass extrapolations needed to compute hadronic observables.

Guo, F -K; Llanes-Estrada, F J; Meißner, U -G

2011-01-01

217

Energy Technology Data Exchange (ETDEWEB)

One of the central problems in environmental toxicology has been the extrapolation from laboratory tests to the field and from biomonitoring results to ecological impacts. The crossing of the boundary from molecular mechanisms to population impacts has always been difficult. Perhaps the problem in extrapolation is not so much the effects of physical scale as much as the transition boundary between two different types of systems, organismal and non-organismal. The basic properties of these systems are quite distinct. Organismal systems possess a central core of information, subject to natural selection, that can impose homeostasis (body temperature) or diversity (immune system) upon the constituents of that system. Unless there are changes in the genetic structure of the germ line, impacts to the somatic cells and structure of the organism are erased upon the establishment of a new generation. The integrity of the germplasm means that organismal systems are largely a historical. In contrast, non-organismal systems contain no central and inheritable repository of information, analogous to the genome, that serves as the blueprint for an ecological system. Non-organismal systems are historical in the terminology of complex systems. The irreversibility and historical nature of ecological systems has also been observed experimentally. Historical events and the derived heterogeneity in the field must be taken into account when the extrapolations are conducted. Genetic structure of the populations, the current spatial distribution of species, and the physical structure of the system must all be taken into account if accurate forecasts from experimental results can be made.

Landis, W.G. [Western Washington Univ., Bellingham, WA (United States)

1995-12-31

218

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

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

219

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 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.

2011-01-01

220

Energy Technology Data Exchange (ETDEWEB)

Because of the need to significantly extend the lifetimes of weapons, and because of potential implications of environmental O-ring failure on degradation of critical internal weapon components, the authors have been working on improved methods of predicting and verifying O-ring lifetimes. In this report, they highlight the successful testing of a new predictive method for deriving more confident lifetime extrapolations. This method involves ultrasensitive oxygen consumption measurements. The material studied is an EPDM formulation use for the environmental O-ring the W88. Conventional oven aging (155 C to 111 C) was done on compression molded sheet material; periodically, samples were removed from the ovens and subjected to various measurements, including ultimate tensile elongation, density and modulus profiles. Compression stress relaxation (CSR) measurements were made at 125 C and 111 C on disc shaped samples (12.7 mm diameter by 6 mm thick) using a Shawbury Wallace Compression Stress Relaxometer MK 2. Oxygen consumption measurements were made versus time, at temperatures ranging from 160 C to 52 C, using chromatographic quantification of the change in oxygen content caused by reaction with the EPDM material in sealed containers.

Gillen, K.T.; Wise, J.; Celina, M.; Clough, R.L.

1997-09-01

221

Identification of Fe XVII and Ni XIX in solar flares based on isoelectronic extrapolations

Energy Technology Data Exchange (ETDEWEB)

Twenty-four lines in solar flare spectra in the region 200-410 A have been identified as transitions between the 2s/sup 2/2p/sup 5/3s, 3p and 3d configurations in Fe XVII and Ni XIX. The identifications are based on isoelectronic extrapolations of differences between experimental and theoretical wave-numbers along the neon-like sequence. A predicted wavelength for the magnetic dipole transition 2s/sup 2/2p/sup 5/(/sup 3/P/sub 1/-/sup 3/P/sub 0/) in Fe XVII is also given.

Jupen, C.

1984-05-01

222

CHARACTERISTICS OF THE H-MODE PEDESTAL AND EXTRAPOLATION TO ITER

International Nuclear Information System (INIS)

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 ? 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.

2002-01-01

223

Standardization of beta dose rate using an extrapolation chamber for skin dose measurements

International Nuclear Information System (INIS)

The calibration of a beta skin dose monitor developed by Electronics Division, BARC was done as a first step to verify its conformity with the international standard ISO 6980-1. An extrapolation chamber was used to standardize the dose rate of a 90Sr- 90Y beta source. Standardization of the beta source was done in terms of dose to skin for calibration of field instruments. Effective area of the source was determined by determining the 50% isodose contours of the GAFCHROMIC films exposed. Field was standardized for various source to surface distances. The paper gives the details of measurement technique, analysis of data and the results. (author)

2010-01-01

224

On the internal stepsize of an extrapolation algorithm for IVP in ODE

We propose an extrapolation algorithm for initial value problems in ordinary differential equations. In the algorithm, an appropriately chosen stepsizeH is divided into smaller stepsizes by a sequence and a new stopping rule is proposed. The sequences applied to the algorithm are Romberg {2,4,8,16,32,...}, Bulirsch {2,4,6,8,16...} and Harmonic {2,4,6,8,10,12,...} types. The proposed algorithm is compared numerically with the algorithm introduced by Stoer. In view of the accuracy of numerical solutions, the relatively small number of calculations, the stability and reliability of the algorithm, we found that the algorithm with the Romberg sequence is the best.

Murofushi, Makoto; Nagasaka, Hideko

1992-12-01

225

Impact of new collider data on fits and extrapolations of cross sections and slopes

International Nuclear Information System (INIS)

The latest Collider data are compared with our earlier extrapolations. Fits that include the new data are made. Those for which sigma/sub tot/ grows as log2(s/s/sub o/) indefinitely give a significantly poorer chi2 than those for which sigma/sub tot/ eventually levels out. For the proposed SSC energy for the former fits predict sigma/sub tot/(?s = 40 TeV) approx. =200 mb while the latter give sigma/sub tot/(?s = 40 TeV) approx. = 100 mb. 6 refs.

1985-01-01

226

Impact of new collider data on fits and extrapolations of cross sections and slopes

Energy Technology Data Exchange (ETDEWEB)

The latest Collider data are compared with our earlier extrapolations. Fits that include the new data are made. Those for which sigma/sub tot/ grows as log/sup 2/(s/s/sub o/) indefinitely give a significantly poorer chi/sup 2/ than those for which sigma/sub tot/ eventually levels out. For the proposed SSC energy for the former fits predict sigma/sub tot/(..sqrt..s = 40 TeV) approx. =200 mb while the latter give sigma/sub tot/(..sqrt..s = 40 TeV) approx. = 100 mb. 6 refs.

Block, M.M.; Cahn, R.N.

1985-08-01

227

International Nuclear Information System (INIS)

The radioactive wastes that would be produced in demonstration and commercial fusion reactors which could be extrapolated from the design database that will be provided by ITER and its supporting R and D and from a design database supplemented by advanced physics and advanced materials R and 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. (orig.).

1994-07-01

228

Practical parallel implementation of the nonstationary integral wavefield extrapolators is presented. Two approaches, the windowed split-step algorithm and full integral algorithm, were implemented. The integral extrapolators are suitable for large-step wavefield extrapolation, even when lateral velocity variations are strong, provided that the static phase-shift and the focusing phase-shift velocities are replaced by time-average and depth-average velocities, respectively. Linear vertical wavefield interpolation between reference wavefields produced by large-step extrapolation algorithms can be used to compute the intermediate depth image. This dual algorithm significantly reduces the run time of the integral wavefield extrapolators. Nonstationary extrapolators are found to be very capable of imaging shallow events at large dipping angles as well as at deep events, even when severe topography variations and high near-surface velocity is present. The Marmousi synthetic data set and the Alberta Foothills synthetic data set were migrated and superior depth images were achieved. P-P prestack depth imaging techniques can be conveniently applied to converted-wave data based on the primary-only P-S wave propagation model. Prestack P-S shot gather migration with the dual algorithm produced a very good depth image for the 1997 Blackfoot 3C-2D survey. The concept of downward-continuation migration velocity analysis (DMVA) is proposed. It can be used to partially eliminate the assumption of laterally invariant velocity in the established migration velocity analysis techniques and hence provide a better velocity estimation.

Mi, Yanpeng

229

Evaluation of time extrapolation factors based on the database RepDose.

In chemical risk assessment for many substances only short-term animal studies are available for the evaluation of long-term human exposure. Therefore usually extrapolation factors (EF) are used to extrapolate NOAELs from existing short-term studies to NOAELs for long term exposure. In this report time EFs are derived, based on NOEL/C or LOEL/C ratios (short term N(L)OEL/long term N(L)OEL) from the large datasets of the database RepDose (www.fraunhofer-repdose.de) on repeated dose toxicity for oral or inhalation administration. Within a tiered approach several sources of variability, e.g. use of LOEL/C ratios or differences in dose spacing were analyzed and if needed subsequently excluded. The reduction of data variability resulted in "final" EFs datasets, which are as far as possible based on compound-specific, time-dependent differences in toxicity. For distribution functions of oral repeated dose toxicity studies characterised by GM, GSD and 90th percentiles the following data are obtained: subacute-to-subchronic - GM 1.3, GSD 2.4, 90th 4.0, subacute-to-chronic - GM 3.4, GSD 3.7, 90th 18.2, and subchronic-to-chronic - GM 1.4, GSD 2.1, 90th 3.6. The number of data for inhalation exposure is limited, but with regard to systemic toxicity the derived EFs confirm the respective oral EFs. PMID:21640805

Batke, M; Escher, S; Hoffmann-Doerr, S; Melber, C; Messinger, H; Mangelsdorf, I

2011-05-27

230

Evaluation of time extrapolation factors based on the database RepDose.

UK PubMed Central (United Kingdom)

In chemical risk assessment for many substances only short-term animal studies are available for the evaluation of long-term human exposure. Therefore usually extrapolation factors (EF) are used to extrapolate NOAELs from existing short-term studies to NOAELs for long term exposure. In this report time EFs are derived, based on NOEL/C or LOEL/C ratios (short term N(L)OEL/long term N(L)OEL) from the large datasets of the database RepDose (www.fraunhofer-repdose.de) on repeated dose toxicity for oral or inhalation administration. Within a tiered approach several sources of variability, e.g. use of LOEL/C ratios or differences in dose spacing were analyzed and if needed subsequently excluded. The reduction of data variability resulted in "final" EFs datasets, which are as far as possible based on compound-specific, time-dependent differences in toxicity. For distribution functions of oral repeated dose toxicity studies characterised by GM, GSD and 90th percentiles the following data are obtained: subacute-to-subchronic - GM 1.3, GSD 2.4, 90th 4.0, subacute-to-chronic - GM 3.4, GSD 3.7, 90th 18.2, and subchronic-to-chronic - GM 1.4, GSD 2.1, 90th 3.6. The number of data for inhalation exposure is limited, but with regard to systemic toxicity the derived EFs confirm the respective oral EFs.

Batke M; Escher S; Hoffmann-Doerr S; Melber C; Messinger H; Mangelsdorf I

2011-08-01

231

Extrapolation codes for modelling the magnetic field in the corona in cartesian geometry do not take the curvature of the Sun's surface into account and can only be applied to relatively small areas, \\textit{e.g.}, a single active region. We apply a method for nonlinear force-free coronal magnetic field modelling of photospheric vector magnetograms in spherical geometry which allows us to study the connectivity between multi-active regions. We use vector magnetograph data from the Synoptic Optical Long-term Investigations of the Sun survey (SOLIS)/Vector Spectromagnetograph(VSM) to model the coronal magnetic field, where we study three neighbouring magnetically connected active regions (ARs: 10987, 10988, 10989) observed on 28, 29, and 30 March 2008, respectively. We compare the magnetic field topologies and the magnetic energy densities and study the connectivities between the active regions(ARs). We have studied the time evolution of magnetic field over the period of three days and found no major changes in...

Tadesse, T; Inhester, B; Pevtsov, A; 10.1007/s11207-011-9764-z

2011-01-01

232

Directory of Open Access Journals (Sweden)

Full Text Available Background : Therapeutic drug monitoring for mycophenolic acid (MPA) is increasingly being advocated. Thepresent therapeutic range relates to the 12-hour area under the serum concentration time profile (AUC).However, this is a cumbersome, tedious, cost restricting procedure. Is it possible to reduce this samplingperiod? Aim : To compare the AUC from a reduced sampling strategy with the full 12-hour profile for MPA. Settings and Design : Clinical Pharmacology Unit of a tertiary care hospital in South India. Retrospective, paireddata. Materials and Methods : Thirty-four 12-hour profiles from post-renal transplant patients on Cellcept ® wereevaluated. Profiles were grouped according to steroid and immunosuppressant co-medication and the timeafter transplant. MPA was estimated by high performance liquid chromatography with UV detection. From the12-hour profiles the AUC up to only six hours was calculated by the trapezoidal rule and a correction factorapplied. These two AUCs were then compared. Statistical Analysis : Linear regression, intra-class correlations (ICC) and a two-tailed paired t-test were appliedto the data. Results : Comparing the 12-hour AUC with the paired 6-hour extrapolated AUC, the ICC and linear regression(r2) were very good for all three groups. No statistical difference was found by a two-tailed paired t-test. Nobias was seen with a Bland Altman plot or by calculation. Conclusion : For patients on Cellcept ® with prednisolone ± cyclosporine the 6-hour corrected is an accuratemeasure of the full 12-hour AUC.

Fleming D; Mathew B; John G; Chandy S; Manivannan J; Jeyaseelan V

2006-01-01

233

Energy Technology Data Exchange (ETDEWEB)

New experimental results on transient loads during ELMs and disruptions in present divertor tokamaks are described and used to carry out a extrapolation to ITER reference conditions and to draw consequences for its operation. In particular, the achievement of low energy/convective type I edge localized modes (ELMs) in ITER-like plasma conditions seems the only way to obtain transient loads which may be compatible with an acceptable erosion lifetime of plasma facing components (PFCs) in ITER. Power loads during disruptions, on the contrary, seem to lead in most cases to an acceptable divertor lifetime because of the relatively small plasma thermal energy remaining at the thermal quench and the large broadening of the power flux footprint during this phase. These conclusions are reinforced by calculations of the expected erosion lifetime, under these load conditions, which take into account a realistic temporal dependence of the power fluxes on PFCs during ELMs and disruptions.

Loarte, A [EFDA Close Support Unit Garching, D-85748 Garching (Germany); Saibene, G [EFDA Close Support Unit Garching, D-85748 Garching (Germany); Sartori, R [EFDA Close Support Unit Garching, D-85748 Garching (Germany); Riccardo, V [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon OX113 3EA (United Kingdom); Andrew, P [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon OX113 3EA (United Kingdom); Paley, J [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon OX113 3EA (United Kingdom); Fundamenski, W [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon OX113 3EA (United Kingdom); Eich, T [Association Euratom-Max-Planck Institut fuer Plasmaphysik, D-85748 Garching (Germany); Herrmann, A [Association Euratom-Max-Planck Institut fuer Plasmaphysik, D-85748 Garching (Germany); Pautasso, G [Association Euratom-Max-Planck Institut fuer Plasmaphysik, D-85748 Garching (Germany); Kirk, A [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon OX113 3EA (United Kingdom); Counsell, G [Euratom-UKAEA Fusion Association, Culham Science Centre, Abingdon OX113 3EA (United Kingdom); Federici, G [ITER International Team, Garching Working Site, D-85748 Garching (Germany); Strohmayer, G [ITER International Team, Garching Working Site, D-85748 Garching (Germany); Whyte, D [DIII-D National Fusion Facility, P O Box 85608, San Diego, CA 92186 (United States); Leonard, A [DIII-D National Fusion Facility, P O Box 85608, San Diego, CA 92186 (United States); Pitts, R A [CRPP-EPFL, Association EURATOM - Confederation Suisse, 1015 Lausanne (Switzerland); Landman, I [Forschungszentrum Karlsruhe, IHM, P O Box 3640, 76021 Karlsruhe (Germany); Bazylev, B [Forschungszentrum Karlsruhe, IHM, P O Box 3640, 76021 Karlsruhe (Germany); Pestchanyi, S [Forschungszentrum Karlsruhe, IHM, P O Box 3640, 76021 Karlsruhe (Germany)

2007-03-15

234

International Nuclear Information System (INIS)

New experimental results on transient loads during ELMs and disruptions in present divertor tokamaks are described and used to carry out a extrapolation to ITER reference conditions and to draw consequences for its operation. In particular, the achievement of low energy/convective type I edge localized modes (ELMs) in ITER-like plasma conditions seems the only way to obtain transient loads which may be compatible with an acceptable erosion lifetime of plasma facing components (PFCs) in ITER. Power loads during disruptions, on the contrary, seem to lead in most cases to an acceptable divertor lifetime because of the relatively small plasma thermal energy remaining at the thermal quench and the large broadening of the power flux footprint during this phase. These conclusions are reinforced by calculations of the expected erosion lifetime, under these load conditions, which take into account a realistic temporal dependence of the power fluxes on PFCs during ELMs and disruptions.

2007-01-01

235

Top background extrapolation for H?WW searches at the CERN LHC

International Nuclear Information System (INIS)

A leading order (LO) analysis is presented that demonstrates that key top backgrounds to H?W+W-?l±l±peT decays in weak boson fusion (WBF) and gluon fusion (GF) at the CERN Large Hadron Collider can be extrapolated from experimental data with an accuracy of order 5% to 10%. If LO scale variation is accepted as proxy for the theoretical error, parton level results indicate that the tt-barj background to the H?WW search in WBF can be determined with a theoretical error of about 5%, while the tt-bar background to the H?WW search in GF can be determined with a theoretical error of better than 1%. Uncertainties in the parton distribution functions contribute an estimated 3% to 10% to the total error

2004-07-01

236

UK PubMed Central (United Kingdom)

Recent research has shown that hatchery coho salmon (Oncorhynchus kisutch) are vulnerable to the olfactory neurotoxicity caused by copper from urban runoff, pesticide use, and mining activities. To explore the broader application of this data to salmonids living in the wild, we exposed naturally-reared steelhead (O. mykiss) to copper (5 and 20 ?g/L; 3h) and measured losses in olfactory function via electro-olfactogram (EOG) recordings. Copper exposure disrupted the olfactory responsiveness of steelhead to an amino acid (L-serine) in a dose-dependent manner that was equivalent to previously published data for hatchery coho. Our findings support extrapolation of copper toxicity data across species and from fish raised in hatcheries to fish in the wild.

Baldwin DH; Tatara CP; Scholz NL

2011-01-01

237

Linear Extrapolation Of Ultrarelativistic Nucleon-Nucleon Scattering To Nucleus-Nucleus Collisions

UK PubMed Central (United Kingdom)

We use a Glauber-like approach to describe very energetic nucleus-nucleus collisions asa sequence of binary nucleon-nucleon collisions. No free parameters are needed: all theinformation comes from simple parametrizations of nucleon-nucleon collision data. Producedmesons are assumed not to interact with each other or with the original baryons.Comparisons are made to published experimental measurements of baryon rapidity andtransverse momentum distributions, negative hadron rapidity and transverse momentumdistributions, average multiplicities of pions, kaons, hyperons, and antihyperons, and zerodegree energy distributions for sulfur-sulfur collisions at 200 GeV=c per nucleon and forlead-lead collisions at 158 GeV=c per nucleon. Good agreement is found except thatthe number of strange particles produced, especially antihyperons, is too small comparedwith experiment. We call this model LEXUS: it is a baseline linear extrapolation ofultrarelativistic nucleon-nucleon scattering to...

Sangyong Jeon; Joseph Kapusta

238

To examine the validity of extrapolating parenteral product bioequivalence determinations across target animal species, the relative bioavailability of two injectable formulations of ampicillin trihydrate (PolyflexR, a water-based suspension, and Ampi-kel 10R, an oil-based suspension) was examined in calves, sheep and swine. Employing products recognized to be bioinequivalent provided an opportunity to explore potential species-by-formulation interactions. As compared with PolyflexR, Ampi-kel 10R exhibited lower area under the curve (AUC) estimates but higher peak concentrations in all target animal species. Nevertheless, marked interspecies differences were noted in the width and bounds of the confidence intervals about the differences in treatment means. Potential physiological and physico-chemical reasons for these findings are discussed. PMID:11442787

Martinez, M N; Pedersoli, W M; Ravis, W R; Jackson, J D; Cullison, R

2001-04-01

239

UK PubMed Central (United Kingdom)

To examine the validity of extrapolating parenteral product bioequivalence determinations across target animal species, the relative bioavailability of two injectable formulations of ampicillin trihydrate (PolyflexR, a water-based suspension, and Ampi-kel 10R, an oil-based suspension) was examined in calves, sheep and swine. Employing products recognized to be bioinequivalent provided an opportunity to explore potential species-by-formulation interactions. As compared with PolyflexR, Ampi-kel 10R exhibited lower area under the curve (AUC) estimates but higher peak concentrations in all target animal species. Nevertheless, marked interspecies differences were noted in the width and bounds of the confidence intervals about the differences in treatment means. Potential physiological and physico-chemical reasons for these findings are discussed.

Martinez MN; Pedersoli WM; Ravis WR; Jackson JD; Cullison R

2001-04-01

240

Top Background Extrapolation for $H \\to WW$ Searches at the LHC

A leading order (LO) analysis is presented that demonstrates that key top backgrounds to H -> W^+W^- -> l^\\pm l^\\mp \\sla{p}_T decays in weak boson fusion (WBF) and gluon fusion (GF) at the CERN Large Hadron Collider can be extrapolated from experimental data with an accuracy of order 5% to 10%. If LO scale variation is accepted as proxy for the theoretical error, parton level results indicate that the tt~j background to the H -> WW search in WBF can be determined with a theoretical error of about 5%, while the tt~ background to the H -> WW search in GF can be determined with a theoretical error of better than 1%. Uncertainties in the parton distribution functions contribute an estimated 3% to 10% to the total error.

Kauer, N

2004-01-01

241

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

242

Age of Eocene/Oligocene boundary based on extrapolation from North American microtektite layer

Energy Technology Data Exchange (ETDEWEB)

Microtektites believed to belong to the North American tektite strewn field have been found in upper Eocene sediments in cores from nine Deep Sea Drilling Project sites in the Caribbean Sea, Gulf of Mexico, equatorial Pacific, and eastern equatorial Indian Ocean. The microtektite layer has an age of 34.2 +- 0.6 m.y. based on fission-track dating of the microtektites and K-Ar and fission-track dating of the North American tektites. Extrapolation from the microtektite layer to the overlying Eocene/Oligocene boundary indicates an age of 32.3 +- 0.9 m.y. for the Eocene/Oligocene boundary as defined at each site in the Initial Reports of the Deep Sea Drilling Project. This age is approximately 5 m.y. younger than the age of 37.5 m.y. that is generally assigned to the boundary based on recently published Cenozoic time scales. 3 figures, 5 tables.

Glass, B.P.; Crosbie, J.R.

1982-04-01

243

On the effectiveness of CCSD(T) complete basis set extrapolations for atomization energies

The leading cause of error in standard coupled cluster theory calculations of thermodynamic properties such as atomization energies and heats of formation originates with the truncation of the one-particle basis set expansion. Unfortunately, the use of finite basis sets is currently a computational necessity. Even with basis sets of quadruple zeta quality, errors can easily exceed 8 kcal/mol in small molecules, rendering the results of little practical use. Attempts to address this serious problem have led to a wide variety of proposals for simple complete basis set extrapolation formulas that exploit the regularity in the correlation consistent sequence of basis sets. This study explores the effectiveness of six formulas for reproducing the complete basis set limit. The W4 approach was also examined, although in lesser detail. Reference atomization energies were obtained from standard coupled-cluster singles, doubles, and perturbative triples (CCSD(T)) calculations involving basis sets of 6? or better quality for a collection of 141 molecules. In addition, a subset of 51 atomization energies was treated with explicitly correlated CCSD(T)-F12b calculations and very large basis sets. Of the formulas considered, all proved reliable at reducing the one-particle expansion error. Even the least effective formulas cut the error in the raw values by more than half, a feat requiring a much larger basis set without the aid of extrapolation. The most effective formulas cut the mean absolute deviation by a further factor of two. Careful examination of the complete body of statistics failed to reveal a single choice that out performed the others for all basis set combinations and all classes of molecules.

Feller, David; Peterson, Kirk A.; Grant Hill, J.

2011-07-01

244

On the effectiveness of CCSD(T) complete basis set extrapolations for atomization energies.

UK PubMed Central (United Kingdom)

The leading cause of error in standard coupled cluster theory calculations of thermodynamic properties such as atomization energies and heats of formation originates with the truncation of the one-particle basis set expansion. Unfortunately, the use of finite basis sets is currently a computational necessity. Even with basis sets of quadruple zeta quality, errors can easily exceed 8 kcal/mol in small molecules, rendering the results of little practical use. Attempts to address this serious problem have led to a wide variety of proposals for simple complete basis set extrapolation formulas that exploit the regularity in the correlation consistent sequence of basis sets. This study explores the effectiveness of six formulas for reproducing the complete basis set limit. The W4 approach was also examined, although in lesser detail. Reference atomization energies were obtained from standard coupled-cluster singles, doubles, and perturbative triples (CCSD(T)) calculations involving basis sets of 6? or better quality for a collection of 141 molecules. In addition, a subset of 51 atomization energies was treated with explicitly correlated CCSD(T)-F12b calculations and very large basis sets. Of the formulas considered, all proved reliable at reducing the one-particle expansion error. Even the least effective formulas cut the error in the raw values by more than half, a feat requiring a much larger basis set without the aid of extrapolation. The most effective formulas cut the mean absolute deviation by a further factor of two. Careful examination of the complete body of statistics failed to reveal a single choice that out performed the others for all basis set combinations and all classes of molecules.

Feller D; Peterson KA; Hill JG

2011-07-01

245

UK PubMed Central (United Kingdom)

Modeling historic air pollution exposures is often restricted by availability of monitored concentration data. We evaluated back-extrapolation of land use regression (LUR) models for annual mean NO2 concentrations in Great Britain for up to 18 years earlier. LUR variables were created in a geographic information system (GIS) using land cover and road network data summarized within buffers, site coordinates, and altitude. Four models were developed for 2009 and 2001 using 75% of monitoring sites (in different groupings) and evaluated on the remaining 25%. Variables selected were generally stable between models. Within year, hold-out validation yielded mean-squared-error-based R(2) (MSE-R(2)) (i.e., fit around the 1:1 line) values of 0.25-0.63 and 0.51-0.65 for 2001 and 2009, respectively. Back-extrapolation was conducted for 2009 and 2001 models to 1991 and for 2009 models to 2001, adjusting to the year using two background NO2 monitoring sites. Evaluation of back-extrapolated predictions used 100% of sites from an historic national NO2 diffusion tube network (n = 451) for 1991 and 70 independent sites from automatic monitoring in 2001. Values of MSE-R(2) for back-extrapolation to 1991 were 0.42-0.45 and 0.52-0.55 for 2001 and 2009 models, respectively, but model performance varied by region. Back-extrapolation of LUR models appears valid for exposure assessment for NO2 back to 1991 for Great Britain.

Gulliver J; de Hoogh K; Hansell A; Vienneau D

2013-07-01

246

UK PubMed Central (United Kingdom)

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%.

Neves LP; Silva EA; Perini AP; Maidana NL; Caldas LV

2012-07-01

247

In this paper, we generalize the $A_\\fz$ extrapolation theorem in \\cite{cmp} and the $A_p$ extrapolation theorem of Rubio de Francia to Schr\\"odinger settings. In addition, we also establish the weighted vector-valued inequalities for Schr\\"odinger type maximal operators by using weights belonging to $ A_p^{\\rho,\\tz}$ which includes $A_p$. As their applications, we establish the weighted vector-valued inequalities for some Sch\\"odinger type operators and pseudo-differential operators.

Tang, Lin

2011-01-01

248

Energy Technology Data Exchange (ETDEWEB)

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.

Singh, N.P.; Zimmerman, C.J.; Taylor, G.N.; Wrenn, M.E.

1988-03-01

249

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

250

Opportunities for improving techniques for interspecies extrapolation in the risk assessment process

Energy Technology Data Exchange (ETDEWEB)

Quantitative estimates of human carcinogenic risk from chemical exposure are currently derived primarily from linearized multistage model analyses of the tumor response as observed in chronic laboratory animal bioassays versus administered dose. The numerous ad hoc assumptions that provide a rationale for this generic approach to carcinogenic risk assessment can only be evaluated critically when mechanistic data directly relevant to the low-dose and interspecies extrapolation problems are available. Clear needs exist to develop such ancillary data bases and the mean for explicitly incorporating them into the risk estimation process. Target site dosimetry provides one useful organizing concept. Physiological response modeling can account systematically for interspecies variations in the distribution and disposition of chemicals in relation to external measures of exposure. Direct measurements of interactions of chemicals and their metabolites with specific target macromolecules can provide sensitive and biologically meaningful exposure indices. Alternatively, quantitation of toxic effects such as altered cell regulation and differentiation can serve the same purpose. Virus and oncogene activation, DNA damage and repair, and enhanced cell proliferation provide additional biological markers of exposure. They may also comprise critical elements of the carcinogenic process. Identification of the actual mechanisms involved should eventually lead to the development of risk assessment models that adequately reflect the unique biological and toxicological characteristics of different species-chemical combinations.

Gibson, J.E.; Starr, T.B.

1988-04-01

251

Evidence for Solar Tether-cutting Magnetic Reconnection from Coronal Field Extrapolations

Magnetic reconnection is one of the primary mechanisms for triggering solar eruptive events, but direct observation of its rapid process has been of challenge. In this Letter we present, using a nonlinear force-free field (NLFFF) extrapolation technique, a visualization of field line connectivity changes resulting from tether-cutting reconnection over about 30 minutes during the 2011 February 13 M6.6 flare in NOAA AR 11158. Evidence for the tether-cutting reconnection was first collected through multiwavelength observations and then by the analysis of the field lines traced from positions of four conspicuous flare 1700 A footpoints observed at the event onset. Right before the flare, the four footpoints are located very close to the regions of local maxima of magnetic twist index. Especially, the field lines from the inner two footpoints form two strongly twisted flux bundles (up to ~1.2 turns), which shear past each other and reach out close to the outer two footpoints, respectively. Immediately after the fl...

Liu, Chang; Lee, Jeongwoo; Wiegelmann, Thomas; Moore, Ronald L; Wang, Haimin

2013-01-01

252

Energy Technology Data Exchange (ETDEWEB)

The estimation of multimedia health risks associated with industrial chemical emissions involves the mathematical modeling of the fate and transport of chemicals in and between the different environmental media and the prediction of the corresponding concentrations in the foodchain. Among the various chemicals emitted by power plants, mercury has recently received special attention due to its high bioconcentration tendency in fish and the elevated toxicity of its organic, methyl-mercury form. As ingestion appears to be the dominant pathway for mercury risk, the reliable characterization of the processes affecting mercury concentrations in environmental media other than air is of particular importance. Such processes include: (1) intermedia transport (e.g., dry and wet deposition); (2) chemical speciation and transformations; and (3) chemical bioconcentration/bioaccumulation/biomagnification in the foodchain. In the context of this paper, the authors evaluate each of the factors and processes influencing multimedia risks and develop probability distributions for a set of extrapolation factors that can be used to provide estimates of multimedia risks associated with Hg power plant emissions. Particular emphasis is given to: (1) the effect of the hydrologic environment and Hg cycling in surface water bodies (including Hg aquatic chemistry); and (2) the mechanisms affecting Hg uptake by vegetation.

Constantinou, E.; Mitchell, D.; Gerath, M.; Seigneur, C.

1994-12-31

253

Reviewing extrapolation procedures of the electronic properties on the ?-conjugated polymer limit.

UK PubMed Central (United Kingdom)

In this article, the extrapolation procedures of ?-?* electronic transition energy on ?-conjugated oligomers are reexamined. Different models, including the simplest coupled oscillator, the free electron, the Hückel approach, the molecular exciton model, and some specific fitting-functions, are compared using the transition energies derived from theoretical calculations on three thiophene-based oligomer series. Specifically, oligomers of up to 30 repeating units have been considered to include the saturation effects as a function of chain length. The coupled oscillator model of W. Kuhn and the fitting-function of Hirayama are the models that present the better suit on the transition energy interpolation as a function of chain length. Using only the first four oligomers of the series (n = 2 up to 8) yields an estimation of the transition energy on the polymer limit with an average error of ?1.5%. The vertical and adiabatic ionization potential present a better fit with the Hückel model approach. Finally, implications of the environmental polarity on the electronic properties, molecular geometry, charge distribution, and aromaticity are shortly discussed.

Torras J; Casanovas J; Alemán C

2012-07-01

254

Dynamic effects of predators on cyclic voles: field experimentation and model extrapolation.

Mechanisms generating the well-known 3-5 year cyclic fluctuations in densities of northern small rodents (voles and lemmings) have remained an ecological puzzle for decades. The hypothesis that these fluctuations are caused by delayed density-dependent impacts of predators was tested by replicated field experimentation in western Finland. We reduced densities of all main mammalian and avian predators through a 3 year vole cycle and compared vole abundances between four reduction and four control areas (each 2.5-3 km(2)). The reduction of predator densities increased the autumn density of voles fourfold in the low phase, accelerated the increase twofold, increased the autumn density of voles twofold in the peak phase, and retarded the initiation of decline of the vole cycle. Extrapolating these experimental results to their expected long-term dynamic effects through a demographic model produces changes from regular multiannual cycles to annual fluctuations with declining densities of specialist predators. This supports the findings of the field experiment and is in agreement with the predation hypothesis. We conclude that predators may indeed generate the cyclic population fluctuations of voles observed in northern Europe. PMID:12028754

Korpimäki, Erkki; Norrdahl, Kai; Klemola, Tero; Pettersen, Terje; Stenseth, Nils Chr

2002-05-22

255

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

1984-01-01

256

QSAR analysis and data extrapolation among mammals in a series of aliphatic alcohols

Energy Technology Data Exchange (ETDEWEB)

Concepts of QSAR analysis and biological similarity models are combined for use in extrapolation of LD/sub 50/ values after IP application of a series of aliphatic alcohols (C/sub 1/-C/sub 5/) to mouse, hamster, rat, and guinea pig and rabbit. It has been found that although close correlation exists between LD/sub 50/ values after IP and IV applications for mouse and rat, the QSAR obtained with LD/sub 50/ after IV application are not suitable for a prediction of LD/sub 50/ values after IP application for rabbit. Different transformation or distribution processes in mouse, rat, and rabbit after the two types of applications might be the reason. The LD/sub 50/ values (expressed in mmole/m/sup 2/ of body surface) seem to be independent of mammalian species used (at least within the mouse, rat, hamster, and probably guinea pig series). This fact makes it possible to predict reasonable values of LD/sub 50/ after IP application for rabbit. Expression of toxicity in mmole/m/sup 2/ of body surface may be used in toxicological studies. 24 references, 2 figures, 8 tables.

Tichy, M.; Trcka, V.; Roth, Z.; Krivucova, M.

1985-09-01

257

Spatial extrapolation of light use efficiency model parameters to predict gross primary production

Directory of Open Access Journals (Sweden)

Full Text Available To capture the spatial and temporal variability of the gross primary production as a key component of the global carbon cycle, the light use efficiency modeling approach in combination with remote sensing data has shown to be well suited. Typically, the model parameters, such as the maximum light use efficiency, are either set to a universal constant or to land class dependent values stored in look-up tables. In this study, we employ the machine learning technique support vector regression to explicitly relate the model parameters of a light use efficiency model calibrated at several FLUXNET sites to site-specific characteristics obtained by meteorological measurements, ecological estimations and remote sensing data. A feature selection algorithm extracts the relevant site characteristics in a cross-validation, and leads to an individual set of characteristic attributes for each parameter. With this set of attributes, the model parameters can be estimated at sites where a parameter calibration is not possible due to the absence of eddy covariance flux measurement data. This will finally allow a spatially continuous model application. The performance of the spatial extrapolation scheme is evaluated with a cross-validation approach, which shows the methodology to be well suited to recapture the variability of gross primary production across the study sites.

Judith Elisabeth Horn; Karsten Schulz

2011-01-01

258

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

2005-03-10

259

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

260

Extrapolation of stress rupture data on 9 to 12% Cr steels

International Nuclear Information System (INIS)

In this document the stress rupture strengths at times of up to 300 000h have been evaluated. In relation to the stress rupture strength, data from four steels, namely 9Cr1Mo, 9Cr2MoNbV, 9Cr1MoVNb and 12CrMoV, were examined and in each case four different parameters (Larson-Miller, Orr-Sherby-Dorn (original), Orr-Sherby-Dorn (ORNL) and Manson-Haferd) were employed to extrapolate the data out to 300 000h. At temperatures relevant to steam generators (c. 500OC) there was found to be little difference in predicted long-term strength values using the four approaches. However, the lower 95% confidence limits have been evaluated and it was found that for some of the steels these were different to the often assumed minimum set at 80% of the average. The rupture ductility values have been statistically evaluated at specific temperatures to establish the trend in ductility with increasing rupture time

1989-01-01

261

UK PubMed Central (United Kingdom)

OBJECTIVES: To evaluate zolpidem as a mechanism-based inactivator of human CYP3A in vitro, and to assess its metabolic interaction potential with CYP3A drugs (in vitro-in vivo extrapolation; IV-IVE). METHODS: A co- vs. pre-incubation strategy was used to quantify time-dependent inhibition of human liver microsomal (HLM) and recombinant CYP3A4 (rCYP3A4) by zolpidem. Experiments involving a 10-fold dilution step were employed to determine the kinetic constants of inactivation (K (I) and k (inact)) and to assess the in vitro mechanism-based inactivation (MBI) criteria. Inactivation data were entered into the Simcyp population-based ADME simulator to predict the increase in the area under the plasma concentration-time curve (AUC) for orally administered midazolam. RESULTS: Consistent with MBI, the inhibitory potency of zolpidem toward CYP3A was increased following pre-incubation. In HLMs, the concentration required for half maximal inactivation (K (I)) was 122 microM and the maximal rate of inactivation (k (inact)) was 0.094 min(-1). In comparison, K (I) and k (inact) values with rCYP3A4 were 50 microM and 0.229 min(-1), respectively. Zolpidem fulfilled all other in vitro MBI criteria, including irreversible inhibition. The mean oral AUC for midazolam in healthy volunteers was predicted to increase 1.1- to 1.7-fold due to the inhibition of metabolic clearance by zolpidem. Elderly subjects were more sensitive to the interaction, with mean increases in midazolam AUC of 1.2- and 2.2-fold for HLM IV-IVE and rCYP3A4 IV-IVE, respectively. CONCLUSIONS: Zolpidem is a relatively weak mechanism-based inactivator of human CYP3A in vitro. Zolpidem is unlikely to act as a significant perpetrator of metabolic interactions involving CYP3A.

Polasek TM; Sadagopal JS; Elliot DJ; Miners JO

2010-03-01

262

Digital Repository Infrastructure Vision for European Research (DRIVER)

A methodology to efficiently calculate the steady-state solution of fixed-speed induction generator (FSIG) based wind turbines, using a Newton algorithm and a Numerical Differentiation (ND) process for the extrapolation to the limit cycle is presented. This approach can be extremely useful in the de...

Peña Rafael; Medina Aurelio; Anaya-Lara Olimpo

263

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...

264

International Nuclear Information System (INIS)

Indirect justification for extrapolating the Goff-Gratch formula for saturation vapor pressure over liquid water to temperatures as low as -600C has been obtained during a recent study of ice nucleation on aerosol particles in a laboratory cloud chamber.

1983-01-01

265

Energy Technology Data Exchange (ETDEWEB)

Indirect justification for extrapolating the Goff-Gratch formula for saturation vapor pressure over liquid water to temperatures as low as -60/sup 0/C has been obtained during a recent study of ice nucleation on aerosol particles in a laboratory cloud chamber.

Detwiler, A.

1983-03-01

266

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...

267

International Nuclear Information System (INIS)

[en] The Very High Temperature Reactor (VHTR), one of the generation IV reactor systems, is being focused and developed internationally. In Japan, the High Temperature Engineering Test Reactor (HTTR) of the Japan Atomic Energy Agency is in operation, and research and development for the development of commercial High Temperature Gas-Cooled Reactors (HTGRs) are carried out. Nuclear graphites are used for core components of the HTGRs and expansion of irradiation data is necessary when enough irradiation data are not established, because the graphite components in the HTGRs are used at severer condition than that in the HTTR. The necessary database can be established by expansion of existing irradiation data with appropriate interpolation and extrapolation methods. This paper shows the reasonable interpolation and extrapolation method, on dimensional change, thermal conductivity, Young's modulus, strength, irradiation creep strain and coefficient of thermal expansion for IG-110 graphite which is used for the HTTR and a major candidate for the VHTR. The interpolation and extrapolation method was developed so as to be general by using the irradiation data of the other graphites. As a result, irradiation properties of the IG-110 graphite were successfully expanded to the VHTR condition for the first time and the irradiation properties being necessary for the design could be developed. (author)

2009-01-01

268

Mangrove litter fall: Extrapolation from traps to a large tropical macrotidal harbour

Mangrove litter is a major source of organic matter for detrital food chains in many tropical coastal ecosystems, but scant attention has been paid to the substantial challenges in sampling and extrapolation of rates of litter fall. The challenges arise due to within-stand heterogeneity including incomplete canopy cover, and canopy that is below the high tide mark. We sampled litter monthly for three years at 35 sites across eight mapped communities in the macrotidal Darwin Harbour, northern Australia. Totals were adjusted for mean community canopy cover and the occurrence of canopy below the high tide mark. The mangroves of Darwin Harbour generate an estimated average of 5.0 t ha -1 yr -1 of litter. This amount would have been overestimated by 32% had we not corrected for limited canopy cover and underestimated by 11% had we not corrected for foliage that is below the high tide mark. Had we made neither correction, we would have overestimated litter fall by 17%. Among communities, rates varied 2.6-fold per unit area of canopy, and 3.9-fold among unit area of community. Seaward fringe mangroves were the most productive per unit of canopy area but the canopy was relatively open; Tidal creek forest was the most productive per unit area of community. Litter fall varied 1.1-fold among years and 2.0-fold among months though communities exhibited a range of seasonalities. Our study may be the most extensively stratified and sampled evaluation of mangrove litter fall in a tropical estuary. We believe our study is also the first such assessment to explicitly deal with canopy discontinuities and demonstrates that failure to do so can result in considerable overestimation of mangrove productivity.

Metcalfe, Kristin N.; Franklin, Donald C.; McGuinness, Keith A.

2011-11-01

269

International Nuclear Information System (INIS)

This paper deals with the neutronic Monte Carlo simulations with the MCNPX code in view of an experimental gas-cooled Accelerator Driven System (XADS) optimisation and characterization. Accelerator Driven System (ADS), based on a proton accelerator and a sub-critical core coupled with a spallation target, offer advantages in reducing the nuclear waste radiotoxicity before repository closure. Many studies carried out on the ADS should lead to the definition of an experimental plan, which would federate the different works in progress. With this aim, the quite realistic concept of XADS chosen for our investigations comes from the preliminary studies done by Framatome ANP. First, we simulate this basic concept with different fuels and characterize the time evolution of the conceivable fuels, especially with minor actinides. We have calculated the characteristic times and the transmutation rates, concerning minor actinides transmutation. Secondly, we have identified some neutronic differences between an experimental and a power ADS according to the infinite multiplication coefficient, the shape factor and the level of flux to extend the demonstrator concept. Also, we consider the neutronic parameters in view of an extrapolation of the XADS toward a large ADS. We also consider some alternative solutions to reduce the flux peak in the first assemblies around the spallation target of a large ADS and consequently to improve the shape factor and the efficiency of the core. Finally, we focus on the generation of 233U based on a plutonium and minor actinide fuel associated to thorium oxide to start power Molten Salt Reactors (MSR) and to accelerate the transition toward a 232Th/233U cycle which offers an interesting option for nuclear waste reduction and nuclear energy production during many centuries in view of a sustainable development of nuclear energy. (author)

2003-01-01

270

Evaluating the mutagenic potential of chemicals. The minimal battery and extrapolation problems

Energy Technology Data Exchange (ETDEWEB)

Adequate regulations to restrict exposure to chemical mutagens require recognition and evaluation of mutagenic activity. For this purpose a qualitative and an extrapolation phase can be distinguished. For the qualitative phase, the minimal battery should consist of at least three tests, that is: tests for gene- or point mutations in bacteria with and without metabolic activation; two tests for point mutations in eukaryotes, or one such test and a test for the detection of chromosome aberrations in mammalian cells in vitro. Depending on experience and facilities, a choice of two can be made out of the following four test systems: Tests for point mutations in mammalian cells in vitro, with and without metabolic activation; the sex-linked recessive lethal test with Drosophila melanogaster; tests with yeast, Saccharomyces cerevisiae, for point mutations, tests for chromosome aberrations in mammalian cells in vitro. Two different metabolic activation systems should be employed. For further selection of more sensitive test systems, studies on comparative mutagenesis are considered important. A mammalian test for chromosome aberrations in vivo is not included in this minimal battery. The finding that the effective concentration for the production of chromosome breakage events differs from that required to induce point mutations will be briefly discussed. When mutagenic compounds are indispensible or, in the case of ubiquitous exposure, a quantification of risks becomes necessary and here one is confronted with many difficulties. Information on damage that is hard to measure directly can be obtained in an indirect way by comparison with end-points that can be determined experimentally, such as alkylation per nucleotide.

Sobels, F.H.

1980-11-01

271

Accelerated aging embrittlement of cast duplex stainless steel: Activation energy for extrapolation

International Nuclear Information System (INIS)

Cast duplex stainless steels, used extensively in LWR systems for primary pressure boundary components such as primary coolant pipes, valves, and pumps, are susceptible to thermal aging embrittlement at reactor operating or higher temperatures. Since a realistic aging embrittlement for end-of-life or life-extension conditions (i.e., 32--50 yr of aging at 280--320 degree C) cannot be produced, it is customary to simulate the metallurgical structure by accelerated aging at ?400 degree C. Over the past several years, extensive data on accelerated aging have been reported from a number of laboratories. The most important information from these studies is the activation energy, namely, the temperature dependence of the aging kinetics between 280 and 400 degree C, which is used to extrapolate the aging characteristics to reactor operating conditions. The activation energies (in the range of 18--50 kcal/mole) are, in general, sensitive to material grade, chemical composition, and fabrication process, and a few empirical correlations, obtained as a function of bulk chemical composition, have been reported. In this paper, a mechanistic understanding of the activation energy is described on the basis of the results of microstructural characterization of various heats of CF-3, -8, and -8M grades that were used in aging studies at different laboratories. The primary mechanism of aging embrittlement at temperatures between 280 and 400 degree C is the spinodal decomposition of the ferrite phase, and M23C6 carbide precipitation on the ferrite/austenite boundaries is the secondary mechanism for high-carbon CF-8 grade. 20 refs., 10 figs., 3 tabs

1989-01-01

272

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

2000-01-01

273

DEFF Research Database (Denmark)

Model based short-term forecasting of urban storm water runoff can be applied in realtime control of drainage systems in order to optimize system capacity during rain and minimize combined sewer overflows, improve wastewater treatment or activate alarms if local flooding is impending. A novel online system, which forecasts flows and water levels in real-time with inputs from extrapolated radar rainfall data, has been developed. The fully distributed urban drainage model includes auto-calibration using online in-sewer measurements which is seen to improve forecast skills significantly. The radar rainfall extrapolation (nowcast) limits the lead time of the system to two hours. In this paper, the model set-up is tested on a small urban catchment for a period of 1.5 years. The 50 largest events are presented.

Thorndahl, SØren Liedtke; Rasmussen, Michael R.

2013-01-01

274

The aim of this paper is to derive spatiotemporal extrapolation maps of ocean surface temperature to investigate two global warming effects: On the one hand, the reduction of daily heat fluxes from the sea into the air at the end of the day and during the night, in tropical regions. On the other hand, the strengthening of ocean current flows, due to the increase of ocean surface minimum daily temperature differences between two connected ocean regions. These maps are constructed from the spatial functional time series framework. Specifically, the spatial functional extrapolation of ocean surface temperature from Hawaii Ocean to the Gulf of México reflects an increase of Hawaii Ocean surface temperature in the last 15 years, caused by the reduction of daily heat fluxes from the sea into the air. Furthermore, for the two connected regions of Indian Ocean, and the eastern coast of Australia, the spatial functional extrapolation results derived show more pronounced differences between ocean surface minimum daily temperatures in the year 2003 than in the years 1995-1997. Thus, a strengthening of the flow of the East Australian Current is appreciated.

Ruiz-Medina, M. D.; Espejo, R. M.

2013-06-01

275

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

1994-01-01

276

QUANTITATIVE METHODS FOR CROSS-SPECIES MAPPING (CSM)

Cross species extrapolation will be defined as prediction from one species to another without empirical verification. ross species mapping (CSM) is the same except empirical verification is performed. SM may be viewed as validation of methods for extrapolation. Algorithms for CSM...

277

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

2010-09-22

278

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

279

International Nuclear Information System (INIS)

[en] 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

1989-01-01

280

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

281

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

282

Energy Technology Data Exchange (ETDEWEB)

This appendix to a final report for the Swiss Federal Office of Energy (SFOE) presents the results of measurements made on trains and presents and discusses extrapolations made on the basis of these measurements. The evaluation and selection of the trains on which the measurements were to be made is discussed. Mainly passenger trains were selected as only few goods engines have the necessary equipment and equipping them would be costly. Measurements made on a Re 460 locomotive are presented and discussed. The methods used in the energy analysis are described and the results obtained on several itineraries that include partial single-track working are presented and discussed.

Meyer, M.; Lerjen, M.; Menth, S. [emkamatik GmbH, Wettingen (Switzerland); Luethi, M. [Swiss Federal Insitute of Technology (ETHZ), Institute for Transport Planning and Systems (IVT), Zuerich (Switzerland); Tuchschmid, M. [SBB AG, BahnUmwelt-Center, 3000 Bern (Switzerland)

2009-11-15

283

The present status of Skyrme-Hartree-Fock calculations of nuclear bulk properties is briefly reviewed. Comparison is made to the liquid drop plus shell-correction approach and to semiclassical methods. (48 refs) .

Brack, M

1981-01-01

284

Using a new analytic quantum mechanical method based on Slater's Xalpha method, we show that a fairly accurate estimate of the total energy of a molecule can be obtained from the exact energies of its constituent atoms. The mean absolute error in the total energies thus determined for the G2 set of 56 molecules is about 16 kcal/mol, comparable to or better than some popular pure and hybrid density functional models.

Zope, R R; Zope, Rajendra R.; Dunlap, Brett I.

2005-01-01

285

This paper introduces a surface model with two soil-layers for use in a high-resolution circulation model that has been modified with an extrapolated surface temperature, to be used for the calculation of turbulent fluxes. A quadratic temperature profile based on the layer mean and base temperature is assumed in each layer and extended to the surface. The model is tested at two sites on the Tibetan Plateau near Nam Co Lake during four days during the 2009 Monsoon season. In comparison to a two-layer model without explicit surface temperature estimate, there is a greatly reduced delay in diurnal flux cycles and the modelled surface temperature is much closer to observations. Comparison with a SVAT model and eddy covariance measurements shows an overall reasonable model performance based on RMSD and cross correlation comparisons between the modified and original model. A potential limitation of the model is the need for careful initialisation of the initial soil temperature profile, that requires field measurements. We show that the modified model is capable of reproducing fluxes of similar magnitudes and dynamics when compared to more complex methods chosen as a reference.

Gerken, T.; Babel, W.; Hoffmann, A.; Biermann, T.; Herzog, M.; Friend, A. D.; Li, M.; Ma, Y.; Foken, T.; Graf, H.-F.

2012-04-01

286

A full three-dimensional global potential energy surface is reported first time for the title system, which is important for the photodissociation processes. It is obtained using double many-body expansion theory and an extensive set of accurate ab initio energies extrapolated to the complete basis set limit. Such a work can be recommended for dynamics studies of the N(2D) + H2 reaction, a reliable theoretical treatment of the photodissociation dynamics and as building blocks for constructing the double many-body expansion potential energy surface of larger nitrogen/hydrogen containing systems. In turn, a preliminary theoretical study of the reaction N(2D)+H2(X1?g+)(?=0,j=0)-->NH(a1?)+H(2S) has been carried out with the method of quasi-classical trajectory on the new potential energy surface. Integral cross sections and thermal rate constants have been calculated, providing perhaps the most reliable estimate of the integral cross sections and the rate constants known thus far for such a reaction.

Li, Y. Q.; Ma, F. C.; Sun, M. T.

2013-10-01

287

Energy Technology Data Exchange (ETDEWEB)

Oceanic and atmospheric scientists are interested in the possible role of dimethyl sulfide (DMS) in regulating global climate. DMS is the most abundant volatile organic sulfur compound produced by the ocean. It is derived from biological activity and is the key source of non-sea-salt sulfate aerosols over the ocean. Ecosystem models of marine sulfur cycling can explain how DMS is regulated and how it might respond to climate change. The models consider both spatial/temporal scales and regional/global simulations driven by ocean general circulation models. This paper reviewed ecosystem modelling of carbon and nitrogen dynamics with particular attention to some of their commonalities. Currently, the empirical approach is widely used to extrapolate DMS cycling and fluxes to the global scale. This paper presented a semiempirical method based on a simple ecosystem model. It can reproduce gross features of the global distribution of DMS on surface waters. It can also provide the basis for future modelling of marine sulfur fluxes to the atmosphere. 44 refs., 3 tabs., 3 figs.

Vezina, A.F. [Department of Fisheries and Oceans, Dartmouth, NS (Canada). Bedford Inst. of Oceanography

2004-05-01

288

Influence of Paper Surface Compounds on Corrosion of Printing Machines

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals with investigation of corrosion processes on construction steel in contact with aqueous solutions of surface coatings of high gloss and standard uncoated papers for sheet-fed printing. During the period of four months, changes in the mass of steel specimens were measured (loss of material), as well as changes in pH values and conductivity of the examined solutions. Formation of corrosion products on the surface was identified by changes of spectrophotometric reemission in the visible portion of the steel spectrum and by FT-IR spectral recordings. In addition, the electrochemical potentiodynamic measurements were carried out with the direct current and the method of linear polarization and Tafel’s extrapolation, by which the corrosion parameters were determined: corrosion potential, corrosion current density, polarization resistance cathodic and anodic inclination of Tafel’s lines, as well as the corrosion rate.The results show that the dynamics of the corrosion in printing machines is directly influenced by the type of the paper used for printing. This investigation gave an insight into dynamics and mechanisms of corrosion under conditions close to those in printing production, thus facilitating better understanding of the entire process.

Kresimir Dragcevic; Ante Poljicak

2012-01-01

289

Full-disk nonlinear force-free field extrapolation of SDO/HMI and SOLIS/VSM magnetograms

Extrapolation codes in Cartesian geometry for modelling the magnetic field in the corona do not take the curvature of the Sun's surface into account and can only be applied to relatively small areas, e.g., a single active region. We compare the analysis of the photospheric magnetic field and subsequent force-free modeling based on full-disk vector maps from Helioseismic and Magnetic Imager (HMI) on board solar dynamics observatory (SDO) and Vector Spectromagnetograph (VSM) of the Synoptic Optical Long-term Investigations of the Sun (SOLIS). We use Helioseismic and Magnetic Imager and Vector Spectromagnetograph photospheric magnetic field measurements to model the force-free coronal field above multiple solar active regions, assuming magnetic forces to dominate. We solve the nonlinear force-free field equations by minimizing a functional in spherical coordinates over a full disk excluding the poles. After searching for the optimum modeling parameters for the particular data sets, we compare the resulting nonli...

Tadesse, Tilaye; Inhester, B; MacNeice, P; Pevtsov, A; Sun, X

2012-01-01

290

The SDO/HMI instruments provide photospheric vector magnetograms with a high spatial and temporal resolution. Our intention is to model the coronal magnetic field above active regions with the help of a nonlinear force-free extrapolation code. Our code is based on an optimization principle and has been tested extensively with semi-analytic and numeric equilibria and been applied before to vector magnetograms from Hinode and ground based observations. Recently we implemented a new version which takes measurement errors in photospheric vector magnetograms into account. Photospheric field measurements are often due to measurement errors and finite nonmagnetic forces inconsistent as a boundary for a force-free field in the corona. In order to deal with these uncertainties, we developed two improvements: 1.) Preprocessing of the surface measurements in order to make them compatible with a force-free field 2.) The new code keeps a balance between the force-free constraint and deviation from the photospheric field m...

Wiegelmann, T; Inhester, B; Tadesse, T; Sun, X; Hoeksema, J T

2012-01-01

291

Energy Technology Data Exchange (ETDEWEB)

The alpha emitter plutonium-238 ({sup 238}Pu), 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 {sup 238}PuO{sub 2} have occurred in association with the fabrication of radioisotope thermoelectric generators. Organs and tissue at risk for deterministic and stochastic effects of {sup 238}Pu-alpha irradiation include the lung, liver, skeleton, and lymphatic tissue. Little has been reported about the effects of inhaled {sup 238}PuO{sub 2} 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 {sup 238}PuO{sub 2} particles and to extrapolate results to humans.

Scott, B.R.; Muggenburg, B.A.; Welsh, C.A.; Angerstein, D.A.

1994-11-01

292

International Nuclear Information System (INIS)

The (1+1)-dimensional Hamiltonian q-state ferromagnetic Potts model in an external magnetic field H is studied using finite lattice extrapolation techniques. The possible phases and their boundaries are determined from the ground state energy and the gap in the excitation energy, for arbitrary values of q and both for positive and negative field. We found that, for H positive, there is a critical value qc, where a first order transition line appears for q>qc, starting at the zero field transition point and terminating at a critical point in (h/?, H/?) plane, which separates the disordered phase and the ordered phase in the direction of H. For h negative a critical transition line separating the disordered phase and the others (q-1) ordered phases becomes first order for q>qc. (author). 12 refs, 2 figs

1994-01-01

293

UK PubMed Central (United Kingdom)

Nuclear magnetic resonance (NMR) data for graphenes are mainly lacking in the literature. We provide quantitative first-principles quantum-chemical calculations of NMR chemical shifts and shielding anisotropies as well as spin-spin couplings and anisotropies for increasingly large, hexagon-like fragments of graphene, hydrogenated graphene (graphane) and fluorinated graphene (fluorographene). Due to the rapid convergence of finite molecular model results, the parameter values in the innermost region of large flakes of these materials approach the bulk limit. For nuclear shieldings in the finite band-gap graphane and fluorographene systems, as well as deuterium quadrupole couplings in graphane, these limiting values are verified by periodic gauge-including projector augmented wave (PAW) calculations at corresponding theoretical levels. The periodic PAW wave method was used for all systems to obtain periodic structures. A quantum-chemical cluster approach was used with novel completeness-optimised basis sets to calculate both the shielding and coupling tensors for planar carbon nanoflakes of increasing size. The geometry of the innermost part of the nanoflakes as well as the nuclear shieldings converge toward the periodic counterparts. The cluster method allows the calculation of the spin-spin coupling tensors of all the graphenes and--in contrast to the periodic approach--all the NMR properties for the zero-band-gap graphene itself. The obtained parameters provide a plausible starting point for experimental NMR investigations of graphenes.

Vähäkangas J; Ikäläinen S; Lantto P; Vaara J

2013-04-01

294

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; Jeffrey S. Plouffe

2011-01-01

295

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

1980-01-01

296

Extrapolation of Urn Models via Poissonization: Accurate Measurements of the Microbial Unknown

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 alpha-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 P...

Lladser, Manuel; Reeder, Jens; 10.1371/journal.pone.0021105

2011-01-01

297

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

UK PubMed Central (United Kingdom)

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.

Lladser ME; Gouet R; Reeder J

2011-01-01

298

UK PubMed Central (United Kingdom)

BACKGROUND AND AIM: Investigations on chemical enhancement of skin penetration of gold nanoparticles are considered crucial to have a deeper insight into the main barrier of particle penetration. METHODS: In this study, penetration of gold nanoparticles in the presence of several chemical enhancers - urea, sodium lauryl sulphate, polysorbate 80 and dimethyl sulfoxide (DMSO) - through human skin was studied. RESULTS: Among the tested chemical enhancers, DMSO could induce the penetration of hydrophilic (citrate-stabilized) gold colloid of no intrinsic penetration ability in a concentration-dependent manner. Pretreatment of the skin with DMSO however reduced the penetration of hydrophobic (cetrimide-coated) gold nanoparticles as a result of aggregation in the top layers of the stratum corneum limiting penetration into the deeper skin layers. In addition, nanoparticles-vehicle interaction and the stability of the nanoparticles in the applied vehicle were found important determinants of skin penetration. CONCLUSION: Our results demonstrate that the already established approaches for chemical permeation enhancement of drug molecules and their postulated mechanisms could be used as preliminary guidelines for enhancing the penetration of nanoparticles. At this size range of 15 nm, intercellular lipids provide the main barrier to particle penetration through the stratum corneum.

Labouta HI; El-Khordagui LK; Schneider M

2012-01-01

299

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?; Borut Poljšak

2012-01-01

300

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

301

Evaluation of extrapolation for creep-fatigue life by hysteresis energy

International Nuclear Information System (INIS)

The creep-fatigue life has been evaluated by the hysteresis energy in 316FR stainless steel with low carbon and medium nitrogen, which is a candidate for structural material in Fast Breeder Reactor (FBR) plant with the design life of 60 years. The creep-fatigue is a main damage mode to prevent. The hysteresis energy rate is considered as the parameter to predict the life time. It is clear that the relationship between this parameter and the time to failure can be approximately expressed by the power-law function. The function depends on the ratio of plastic strain to total strain. Total fracture energy for creep-fatigue loading intends to be independent of the ratio of plastic strain to total strain in long-term test condition. The value is related to grain boundary strength for creep-fatigue loading because fracture mode in long-term test condition is intergranular fracture. The life could be predicted by the function in the case of no significant change of fracture energy. Coarse precipitation, for example sigma phase, might be considered as a factor to change the fracture energy. It is important to predict the precipitation formation. The result of life prediction by the hysteresis energy rate is compared with that of the time fraction rule based on 'Demonstration Reactor Design Standard (Draft)'. The predicted lives by both methods for long-term region are comparable and independent of the ratio of plastic strain to total strain. (author)

2011-01-01

302

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.

2010-01-01

303

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

304

UK PubMed Central (United Kingdom)

The present invention provides methods and uses for treating pyropheophytin-containing compositions, particularly in order to remove pyropheophytin therefrom. The compositions are typically plant, algal, or bacterial derived products such as vegetable oils. The method comprises a step of contacting the compositions with an enzyme having pyropheophytinase activity. Also provided are related apparatus and products for performing such methods and uses.

SOEE JOERN BORCH; POULSEN CHARLOTTE HORSMANS; ZARGAHI MASOUD RAJABI; SOERENSEN JENS FRISBAEK; JOERGENSEN TINA; BRUNSTEDT JANNE; MIKKELSEN RENE; MADRID SUSAN MAMPUSTI

305

UK PubMed Central (United Kingdom)

Efavirenz is mainly cleared by the cytochrome P450 (CYP) 2B6. The CYP2B6*6 allele is associated with lower efavirenz clearance. While previous study show that efavirenz clearance is predictable using in vitro data for carriers of the CYP2B6*1/*1 genotype, its prediction in carriers of the CYP2B6*6 allele was poor. To test the hypothesis that incorporation of mechanism of reduced efavirenz metabolism by the CYP2B6*6 allele can predict genetic effect on efavirenz pharmacokinetics, in vitro-in vivo extrapolation (IVIVE) of efavirenz clearance was performed by physiologically-based pharmacokinetic (PBPK) modeling (Simcyp® Simulator) using data obtained from expressed CYP2B6.1 and CYP2B6.6 as well as human liver microsomes (HLMs) with CYP2B6*1/*1, *1/*6 and *6/*6 genotypes. Simulated pharmacokinetics of a single 600 mg oral dose of efavirenz for individuals with each genotype were compared to data observed in healthy subjects genotyped for the CYP2B6*6 allele (n=20). Efavirenz clearance for carriers of the CYP2B6*1/*1 genotype was predicted reasonably well using HLM data, but the clearance in carriers of the CYP2B6*6 allele was under-predicted using both expressed and HLM systems. Improved prediction of efavirenz clearance was obtained from expressed CYP2B6 after recalculating inter-system extrapolation factors for CYP2B6.1 and CYP2B6.6 based on in vitro intrinsic clearance of bupropion 4-hydroxylation. These findings suggest that genetic effect on both CYP2B6 protein expression and catalytic efficiency need to be taken into account for the prediction of pharmacokinetics in individuals carrying the CYP2B6*6/*6 genotype. Expressed CYP2B6 proteins may be a reliable in vitro system to predict effect of the CYP2B6*6 allele on the metabolism of CYP2B6 substrates.

Xu C; Quinney SK; Guo Y; Hall SD; Li L; Desta Z

2013-07-01

306

Absolute liquid scintillation counting of 35S and 45Ca using a modified integral counting method

International Nuclear Information System (INIS)

[en] The disintegration rates of 35S and 45Ca samples were determined by modified integral counting method, which extrapolates the integral count rate to the zero detection threshold of a liquid scintillation spectrometer. The agreement between the extrapolated value and the standardized disintegration rate of the sample is very satisfactory. (author) 6 refs.; 1 fig.; 2 tabs

1994-07-01

307

UK PubMed Central (United Kingdom)

The present invention provides a method of selectively activating and/or targeting stem cells which enables the cells to then be manipulated mechanically in a remote manner wherein the method comprises magnetically manipulating a stem cell in vivo or in vitro by the association of a magnetisable particle within the stem cell.

DOBSON JON; EL HAJ ALICIA

308

Energy Technology Data Exchange (ETDEWEB)

{sup 90}Sr + {sup 90}Y clinical applicators are beta radiation sources utilized in several radiotherapy Brazilian clinics, although don't be more manufactured. These sources are employed in brachytherapy procedures for the treatment of superficial lesions of skin and eyes. International recommendations and previous works determine that dermatological and ophthalmic applicators shall be calibrated periodically, and one of the methods for their calibration consists of the use of an extrapolation chamber. In this work, a method of calibration of {sup 90}Sr + {sup 90}Y clinical applicators was applied using a mini-extrapolation chamber of plane window, developed at the Calibration Laboratory at IPEN, as a reference system. The results obtained were considered satisfactory, when compared with the results given in the calibration certificates of the sources. (author)

Antonio, Patricia L.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Oliveira, Mercia L. [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

2009-07-01

309

UK PubMed Central (United Kingdom)

Accurately quantifying changes in soil carbon (C) stocks with land-use change is important for estimating the anthropogenic fluxes of greenhouse gases to the atmosphere and for implementing policies such as REDD (Reducing Emissions from Deforestation and Degradation) that provide financial incentives to reduce carbon dioxide fluxes from deforestation and land degradation. Despite hundreds of field studies and at least a dozen literature reviews, there is still considerable disagreement on the direction and magnitude of changes in soil C stocks with land-use change. We conducted a meta-analysis of studies that quantified changes in soil C stocks with land use in the tropics. Conversion from one land use to another caused significant increases or decreases in soil C stocks for 8 of the 14 transitions examined. For the three land-use transitions with sufficient observations, both the direction and magnitude of the change in soil C pools depended strongly on biophysical factors of mean annual precipitation and dominant soil clay mineralogy. When we compared the distribution of biophysical conditions of the field observations to the area-weighted distribution of those factors in the tropics as a whole or the tropical lands that have undergone conversion, we found that field observations are highly unrepresentative of most tropical landscapes. Because of this geographic bias we strongly caution against extrapolating average values of land-cover change effects on soil C stocks, such as those generated through meta-analysis and literature reviews, to regions that differ in biophysical conditions.

Powers JS; Corre MD; Twine TE; Veldkamp E

2011-04-01

310

UK PubMed Central (United Kingdom)

The aim of this study was to determine the penetration of doripenem administered intravenously into the rabbit aqueous and vitreous humors. Nineteen New Zealand White rabbits received a 20-mg dose of doripenem intravenously over 60 min. Specimens of aqueous humor, vitreous humor, and blood were obtained 30 min (n = 5), 1 h (n = 5), 2 h (n = 5), and 3 h (n = 4) after the beginning of the infusion and analyzed by high-performance liquid chromatography (HPLC). A pharmacokinetic (PK) model was developed to fit the experimental data. Doripenem concentrations in aqueous humor were lower than those in plasma ultrafiltrates at all sampling times, with an average aqueous humor-to-plasma ultrafiltrate area under the concentration-time curve ratio estimated as 8.3%. A pharmacokinetic model with peripheral elimination described the data adequately and was tentatively used to predict concentration-versus-time profiles and pharmacokinetic-pharmacodynamic (PK-PD) target attainment in patients under various dosing regimens. In conclusion, systematically administered doripenem does not seem to be a promising approach for the treatment of intraocular infections, especially since it could not be detected in the vitreous humor. However, this study has provided an opportunity to develop a new PK modeling approach to characterize the intraocular distribution of doripenem administered intravenously to rabbits, with tentative extrapolation to humans.

Semoun O; Marchand S; Grégoire N; Lamarche I; Adier C; Laroche L; Goldschmidt P; Couet W

2012-07-01

311

The aim of this study was to determine the penetration of doripenem administered intravenously into the rabbit aqueous and vitreous humors. Nineteen New Zealand White rabbits received a 20-mg dose of doripenem intravenously over 60 min. Specimens of aqueous humor, vitreous humor, and blood were obtained 30 min (n = 5), 1 h (n = 5), 2 h (n = 5), and 3 h (n = 4) after the beginning of the infusion and analyzed by high-performance liquid chromatography (HPLC). A pharmacokinetic (PK) model was developed to fit the experimental data. Doripenem concentrations in aqueous humor were lower than those in plasma ultrafiltrates at all sampling times, with an average aqueous humor-to-plasma ultrafiltrate area under the concentration-time curve ratio estimated as 8.3%. A pharmacokinetic model with peripheral elimination described the data adequately and was tentatively used to predict concentration-versus-time profiles and pharmacokinetic-pharmacodynamic (PK-PD) target attainment in patients under various dosing regimens. In conclusion, systematically administered doripenem does not seem to be a promising approach for the treatment of intraocular infections, especially since it could not be detected in the vitreous humor. However, this study has provided an opportunity to develop a new PK modeling approach to characterize the intraocular distribution of doripenem administered intravenously to rabbits, with tentative extrapolation to humans. PMID:22526310

Semoun, Oudy; Marchand, Sandrine; Grégoire, Nicolas; Lamarche, Isabelle; Adier, Christophe; Laroche, Laurent; Goldschmidt, Pablo; Couet, William

2012-04-23

312

Directory of Open Access Journals (Sweden)

Full Text Available Rates of denitrification in sediments were measured with the isotope pairing technique at different sites in the southern and central Baltic Sea. They varied between 0.5 ?mol m?2 h?1 in sands and 28.7 ?mol m?2 h?1 in muddy sediments and showed a good correlation to the organic carbon contents of the surface sediments. N-removal rates via sedimentary denitrification were estimated for the entire Baltic Sea calculating sediment specific denitrification rates and interpolating them to the whole Baltic Sea area. Another approach was carried out by using the relationship between the organic carbon content and the rate of denitrification. For the entire Baltic Sea the N-removal by denitrification in sediments varied between 426–652 kt N a?1, which is around 48–73% of the external N inputs delivered via rivers, coastal point sources and atmospheric deposition. Moreover, an expansion of the anoxic bottom areas was considered under the assumption of a rising oxycline from 100 to 80 m water depth. This leads to an increase of the area with anoxic conditions and an overall decrease in sedimentary denitrification by 14%. Overall we can show here that this type of data extrapolation is a powerful tool to estimate the nitrogen losses for a whole coastal sea and may be applicable to other coastal regions and enclosed seas, too.

B. Deutsch; S. Forster; M. Wilhelm; J. W. Dippner; M. Voss

2010-01-01

313

Directory of Open Access Journals (Sweden)

Full Text Available Rates of denitrification in sediments were measured with the isotope pairing technique at different sites in the southern and central Baltic Sea. The rates varied between 0.5 ?mol N m?2 h?1 in sands and 28.7 ?mol N m?2 h?1 in muddy sediments and showed a good correlation to the organic carbon contents of the surface sediments. N-removal rates via sedimentary denitrification were estimated for the entire Baltic Sea calculating sediment specific denitrification rates and interpolating them to the whole Baltic Sea area. Another approach was carried out by using the relationship between the organic carbon content and the rate of denitrification. The N-removal by denitrification in sediments varied between 426–652 kt N a?1, which is around 48–73% of the external N inputs delivered via rivers, coastal point sources, and atmospheric deposition. Moreover, an expansion of the anoxic bottom areas was considered under the assumption of a rising oxycline from 100 to 80 m water depth. This leads to an increase of the area with anoxic conditions and an overall decrease in sedimentary denitrification by 14%. Overall, we show here that this type of data extrapolation is a powerful tool to estimate the nitrogen losses for a whole coastal sea and may be applicable to other coastal regions and enclosed seas.

B. Deutsch; S. Forster; M. Wilhelm; J. W. Dippner; M. Voss

2010-01-01

314

The accurate assessment of structural errors plays a key role in protein structure prediction, constitutes the first step of protein structure refinement, and has a major impact on subsequent functional inference from structural data. In this study, we assess and compare the ability of different full atom knowledge-based potentials to detect small and localized errors in comparative protein structure models of known accuracy. We have evaluated the effect of incorporating close nonbonded pairwise atom terms on the task of classifying residue modeling accuracy. Since the direct and unbiased derivation of close nonbonded terms from current experimental data is not possible, we extrapolated those terms from the corresponding pseudo-energy functions of a nonlocal knowledge-based potential. It is shown that this methodology clearly improves the detection of errors in protein models, suggesting that a proper description of close nonbonded terms is important to achieve a more complete and accurate description of native protein conformations. The use of close nonbonded terms directly derived from experimental data exhibited a poor performance, demonstrating that these terms cannot be accurately obtained by using the current data and methodology. Some external knowledge-based energy functions that are widely used in model assessment also performed poorly, which suggests that the benchmark of models and the specific error detection task tested in this study constituted a difficult challenge. The methodology presented here could be useful to detect localized structural errors not only in high-quality protein models, but also in experimental protein structures. PMID:17586774

Ferrada, Evandro; Melo, Francisco

2007-07-01

315

UK PubMed Central (United Kingdom)

The accurate assessment of structural errors plays a key role in protein structure prediction, constitutes the first step of protein structure refinement, and has a major impact on subsequent functional inference from structural data. In this study, we assess and compare the ability of different full atom knowledge-based potentials to detect small and localized errors in comparative protein structure models of known accuracy. We have evaluated the effect of incorporating close nonbonded pairwise atom terms on the task of classifying residue modeling accuracy. Since the direct and unbiased derivation of close nonbonded terms from current experimental data is not possible, we extrapolated those terms from the corresponding pseudo-energy functions of a nonlocal knowledge-based potential. It is shown that this methodology clearly improves the detection of errors in protein models, suggesting that a proper description of close nonbonded terms is important to achieve a more complete and accurate description of native protein conformations. The use of close nonbonded terms directly derived from experimental data exhibited a poor performance, demonstrating that these terms cannot be accurately obtained by using the current data and methodology. Some external knowledge-based energy functions that are widely used in model assessment also performed poorly, which suggests that the benchmark of models and the specific error detection task tested in this study constituted a difficult challenge. The methodology presented here could be useful to detect localized structural errors not only in high-quality protein models, but also in experimental protein structures.

Ferrada E; Melo F

2007-07-01

316

Large scale changes in vegetation cover in the Sahelian zone of West Africa may produce changes in climate. However, before any reliable forecasts can be made, fundamental data on the physical and biological processes controlling the energy balance of Sahelian vegetation are urgently required for calibrating global circulation models. To provide some of these data the Institute of Hydrology has recently begun a collaborative project with the ICRISAT Sahelian Center called SEBEX; the Sahelian Energy Balance EXperiment. The main objective of this project is to obtain direct measurements of available energy, evaporation and sensible heat flux from contrasting Sahelian land types in order to see how they might be affected by a change in vegetation. To use these data to calibrate climate models it will be necessary to extrapolate them to much larger areas. A second objective of SEBEX is, therefore, to investigate the possibility of using satellite remote sensing to estimate energy fluxes for areas of the size required for making climate forecasts on a regional scale.

Wallace, J. S.; Wright, I. R.; Stewart, J. B.; Holwill, C. J.

317

International Nuclear Information System (INIS)

[en] The distributions of approximately 7000 flares of importance >= 1 were plotted relative to the sector-structure boundaries of the interplanetary magnetic field (+-) and (-+) extrapolated to the Sun. The data obtained for the time period July 1955 - December 1961 were used. The distributions obtained were analy ed jointly with the same distributions for 1964-1974. It is shown that stable concentration of the flares is observed only near the boundaries (-+) for both hemispheres of the Sun during the increase of the activity and near the maxima cycles No 19 and 20. There are no difference between ''Hale'' and ''non-Hale'' boundaries for these flares. The decrease of the flares was revealed even near the boundary type (+-). For activity decrease phase, after the Sun's general field polarity inversion the concentration of the flares to the boundaries is absent. The difference between Hale and non-Hale boundaries for flares is revealed only in some increase of the flare concentration near the Hale boundaries. The results obtained are likely to give additional evidence in favour of solar magnetic field and flare activity connection

318

The pharmacokinetics of N-(5-oxynicotinoyl)-L-glutamate (ONG) was studied in rats (doses, 20, 100 and 500 mg/kg) and rabbits (50 mg/kg) after bolus administration of calcium salt of N-(5-oxynicotinoyl)-L-glutamic acid (Ampasse preparation). The ONG concentration in the blood serum was determined by HPLC assay with fluorimetric detection. The lower limit of accurate detection for ONG was 100 ng/ml. The ONG pharmacokinetics in rats was linear at relatively small doses (20-100 mg/kg) but nonlinear at a large dose (500 mg/kg). The ONG concentration decay had a two-phase character in both rats and rabbits, so that the pharmacokinetic profiles were fitted to a biexponential equation of the two-compartment model. Systemic pharmacokinetic parameters determined in rats and rabbits, respectively, were as follows: total clearance, 18 and 15 ml/(min kg); steady state distribution volume, 330 and 880 ml/kg; mean retention time, 0.3 and 1.0 h; half-life, 0.73 and 2.3 h. Using the allometric approach to the interspecies extrapolation of the pharmacokinetic data, the half-life of ONG in humans is predicted to be 4 h. PMID:21395015

Firsov, A A; Portno?, Iu A; Dovzhenko, S A; Kobrin, M B; Kiselev, A V; Stovbun, S V; Dolgova, G V; Pomerantseva, T Ia

2010-12-01

319

UK PubMed Central (United Kingdom)

The pharmacokinetics of N-(5-oxynicotinoyl)-L-glutamate (ONG) was studied in rats (doses, 20, 100 and 500 mg/kg) and rabbits (50 mg/kg) after bolus administration of calcium salt of N-(5-oxynicotinoyl)-L-glutamic acid (Ampasse preparation). The ONG concentration in the blood serum was determined by HPLC assay with fluorimetric detection. The lower limit of accurate detection for ONG was 100 ng/ml. The ONG pharmacokinetics in rats was linear at relatively small doses (20-100 mg/kg) but nonlinear at a large dose (500 mg/kg). The ONG concentration decay had a two-phase character in both rats and rabbits, so that the pharmacokinetic profiles were fitted to a biexponential equation of the two-compartment model. Systemic pharmacokinetic parameters determined in rats and rabbits, respectively, were as follows: total clearance, 18 and 15 ml/(min kg); steady state distribution volume, 330 and 880 ml/kg; mean retention time, 0.3 and 1.0 h; half-life, 0.73 and 2.3 h. Using the allometric approach to the interspecies extrapolation of the pharmacokinetic data, the half-life of ONG in humans is predicted to be 4 h.

Firsov AA; Portno? IuA; Dovzhenko SA; Kobrin MB; Kiselev AV; Stovbun SV; Dolgova GV; Pomerantseva TIa

2010-12-01

320

Extrapolation of damage test data to predict performance of large-area NIF optics at 355 nm

Energy Technology Data Exchange (ETDEWEB)

For the aggressive fluence requirements of the NIF laser, some level of laser-induced damage to the large (40 x 40 cm) 351 nm final optics is inevitable. Planning and utilization of NIF therefore requires reliable prediction of the functional degradation of the final optics. Laser damage tests are typically carried out with Gaussian beams on relatively small test areas. The tests yield a damage probability vs energy fluence relation. These damage probabilities are shown to depend on both the beam fluence distribution and the size of area tested. Thus, some analysis is necessary in order to use these test results to determine expected damage levels for large aperture optics. The authors present a statistical approach which interprets the damage probability in terms of an underlying intrinsic surface density of damaging defects. This allows extrapolation of test results to different sized areas and different beam shapes (NIF has a flattop beam). The defect density is found to vary as a power of the fluence (Weibull distribution).

Schwartz, S; Feit, M D; Genin, F Y; Kozlowski, M R; Rubenchik, A M; Sheehan, L M

1998-12-22

321

UK PubMed Central (United Kingdom)

This case report describes the police investigation of a road-traffic accident involving a collision at night (01.00 am) between a car and a truck in which a passenger in the car was killed. The driver of the truck was found responsible for the crash although a roadside breath-alcohol test was negative (<0.1 mg/L breath or 20 mg/100 mL blood). Because of injuries sustained in the crash, the female driver of the car was not breath-tested at the time but was transported to a local hospital for emergency treatment. After swabbing the skin with isopropanol an indwelling catheter was inserted at 01.40 am. A blood sample was taken at 02.10 am and the plasma portion contained 8 mmol/L ethanol according to analysis at the hospital clinical laboratory using a gas chromatographic method. Another blood sample was taken at 05.45 am for analysis of ethanol at a forensic toxicology laboratory, although the result was negative (<10 mg/100 mL). The police authorities wanted an explanation for the discrepancy between the clinical and forensic laboratory results and inquired whether the driver of the car was above the legal alcohol limit (>20 mg/100 mL) at the time of the crash. The scientific basis for converting a plasma-ethanol concentration into a blood-ethanol concentration and back extrapolation of the driver's blood-alcohol concentration (BAC) is explained. The risk of contaminating a blood sample by swabbing the skin with isopropanol is discussed along with the use of alcohol biomarkers (ethyl glucuronide and ethyl sulphate) as evidence of recent drinking.

Jones AW

2011-07-01

322

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper introduces a surface model with two soil-layers for use in a high-resolution circulation model that has been modified with an extrapolated surface temperature, to be used for the calculation of turbulent fluxes. A quadratic temperature profile based on the layer mean and base temperature ...

T. Gerken; W. Babel; A. Hoffmann; T. Biermann; M. Herzog; A. D. Friend; M. Li; Y. Ma; T. Foken; H.-F. Graf

323

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...

324

The application of active carbon method in sandstone uranium region of northern Sichuan

International Nuclear Information System (INIS)

The paper discusses the basic principle of the active carbon method. The good significance of this method for extrapolating the hidden fault zone and deep uranium deposits in northern Sichuan is confirmed also.

1996-01-01

325

Rational Monte Carlo method for flood frequency analysis in urban catchments

Rational Monte Carlo method proposed for flood frequency analysis in urban catchments. Alternative method for Annual Series flood frequency analysis demonstrated for 2011 Toowoomba flash flood. Difficulty in extrapolation of flood probability estimation beyond historical record is demonstrated.

Brodie, Ian M.

2013-04-01

326

Digital Repository Infrastructure Vision for European Research (DRIVER)

Als toepassingsgericht en multidisciplinaire wetenschap behoeft de bestuurskunde een eigen methodologie, naast de algemene sociaalwetenschappelijke methodologie voor het doen van empirisch onderzoek. Deze eigen bestuurskundige methodologie zou kunnen uitgaan van een argumentatieve benadering, gerich...

Edwards, A.R.

327

International Nuclear Information System (INIS)

We exhibit a theoretically-motivated, extraordinarily accurate representation of the recently published probabilities which give the multiplicity distribution of charged hadrons from anti pp collisions at 900 GeV, the highest energy fully analyzed at present. The experimental, corrected probabilities for non-single-diffractive events with n=2 to 104 particles can be described with a ?2 per data point of 25/50, using a single, physically-interpreted parameter in a gamma distribution, in each of two domains. We also describe the data at 546 GeV, and we extrapolate to 2 TeV. (orig.)

1991-01-01

328

Corrosion inhibition of brass by aliphatic amines

International Nuclear Information System (INIS)

[en] 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)

2005-01-01

329

Methods for the assessment of the toxicity of environmental chemicals to earthworms

Energy Technology Data Exchange (ETDEWEB)

In view of the impending publication of standards for earthworm toxicity testing by the Commission of the European Communities, a review has been made of the recent literature on earthworm toxicology. Relevant studies are reviewed from the standpoints of methods used, reproducibility of results, and ability to extrapolate laboratory results to field situations. Eisenia foetida, a commonly used test species, is much less sensitive to agricultural chemicals than other, native earthworms and is of doubtful utility for extrapolating laboratory data to field conditions, but when native soil organisms are used, such extrapolations show good general agreement. Standardization of test conditions and broadening of the data base are encouraged.

Dean-Ross, D.

1983-03-01

330

International Nuclear Information System (INIS)

The austenitic stainless steel X6crni1811 (Din 1.4948) used as a structure material for the German Fast Breeder Reactor SNR 300 was creep tested in a temperature range of 550-650 degree centigree material condition as well as welded material condition. The main point of this program (Extrapolation-Program) lies in the knowledge of the creep-rupture-strength and creep-behaviour up to 3 x 104 hours higher temperatures in order to extrapolated up to ?105 hours for operating temperatures. In order to study the stress dependency of the minimum creep rate additional tests were carried out of 550 degree centigree - 750 degree centigree. The present report describes the state in the running program with test-times of 23.000 hours and results from tests up to 55.000 hours belonging to other parallel programs are taken into account. Besides the creep-rupture behaviour it is also made a study of ductility between 550 and 750 degree centigree. Extensive metallographic examinations have been made to study the fracture behaviour and changes in structure. (Author)

1982-01-01

331

International Nuclear Information System (INIS)

The austenitic stainless steel X6CrNi1811 (DIN 1.4948) 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 creep-rupture-strength and creepbehaviour up to 3 x 104 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 of 550 deg - 750 deg C. The present report describes the state in the running program with test-times of 23.000 hours and results from tests up to 55.000 hours belonging to other parallel programs are taken into account. Besides the creep-rupture behaviour it is also made a study of ductility between 550 and 750 deg C. Extensive metallographic examinations have been made to study the fracture behaviour and changes in structure. (author).

1982-01-01

332

UK PubMed Central (United Kingdom)

In order to determine copper toxicity (LC50) to a local species (Cnesterodon decemmaculatus) in the South American Pilcomayo River water and evaluate a cross-fish-species extrapolation of Biotic Ligand Model, a 96?h acute copper toxicity test was performed. The dissolved copper concentrations tested were 0.05, 0.19, 0.39, 0.61, 0.73, 1.01, and 1.42?mg Cu L(-1). The 96?h Cu LC50 calculated was 0.655?mg L(-1) (0.823 - 0.488). 96-h Cu LC50 predicted by BLM for Pimephales promelas was 0.722?mg L(-1). Analysis of the inter-seasonal variation of the main water quality parameters indicates that a higher protective effect of calcium, magnesium, sodium, sulphate, and chloride is expected during the dry season. The very high load of total suspended solids in this river might be a key factor in determining copper distribution between solid and solution phases. A cross-fish-species extrapolation of copper BLM is valid within the water quality parameters and experimental conditions of this toxicity test.

Casares MV; de Cabo LI; Seoane RS; Natale OE; Castro Ríos M; Weigandt C; de Iorio AF

2012-01-01

333

In order to determine copper toxicity (LC50) to a local species (Cnesterodon decemmaculatus) in the South American Pilcomayo River water and evaluate a cross-fish-species extrapolation of Biotic Ligand Model, a 96?h acute copper toxicity test was performed. The dissolved copper concentrations tested were 0.05, 0.19, 0.39, 0.61, 0.73, 1.01, and 1.42?mg Cu L(-1). The 96?h Cu LC50 calculated was 0.655?mg L(-1) (0.823 - 0.488). 96-h Cu LC50 predicted by BLM for Pimephales promelas was 0.722?mg L(-1). Analysis of the inter-seasonal variation of the main water quality parameters indicates that a higher protective effect of calcium, magnesium, sodium, sulphate, and chloride is expected during the dry season. The very high load of total suspended solids in this river might be a key factor in determining copper distribution between solid and solution phases. A cross-fish-species extrapolation of copper BLM is valid within the water quality parameters and experimental conditions of this toxicity test. PMID:22523491

Casares, María Victoria; de Cabo, Laura I; Seoane, Rafael S; Natale, Oscar E; Castro Ríos, Milagros; Weigandt, Cristian; de Iorio, Alicia F

2012-03-05

334

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)

2011-01-01

335

International Nuclear Information System (INIS)

[en] The austenitic stainless steel X6CrNi1811 (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 550-6500C under base material condition as well as welded material condition. The main point of this program ( Extrapolation Program ) lies in the knowledge of the creep-rupture-strength and creep-behaviour up to 3 x 104 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 of 550-7500C. The present report describes the state in the total running program with test-times up to 55 000 hours. Besides the creep-rupture behaviour it is possible to make a distinct quantitativ statement for the creep-behaviour and ductility. Extensive metallographic and electronmicroscopic examinations show the fracture behaviour and changes in structure. (orig.)

1981-01-01

336

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).

1979-01-01

337

UK PubMed Central (United Kingdom)

Biliary clearance (CLb ) is often underestimated by in vitro-in vivo extrapolation from sandwich-cultured hepatocytes (SCHs). The objective of this study was to compare the performance of a universal correction factor with transporter-based correction factors in correcting underestimation of CLb . The apparent in vitro CLb of a training set of 21 compounds was determined using the SCH model and extrapolated to apparent in vivo CLb (CLb, app ). A universal correction factor (10.2) was obtained by a linear regression of the predicted CLb, app and observed in vivo CLb of training set compounds and applied to an independent test set (n = 20); the corrected CLb predictions of 13 compounds were within twofold error of observed values. Furthermore, two transporter-based correction factors (Organic anion transporting polypeptides/multidrug-resistance-related protein 2 and diffusion/P-glycoprotein) were estimated by linear regression analysis of training set compounds. The applications of the two correction factors to the test set resulted in improved prediction precision. In conclusion, both the universal correction factor and transporter-based correction factors provided reasonable corrections of CLb values, which are often underestimated by the SCH model. The use of transporter-based correction factors resulted in an even greater improvement of predictions for compounds with intermediate-to-high CLb values.

Zou P; Liu X; Wong S; Feng MR; Liederer BM

2013-08-01

338

Multi-gamma windows coincidence method

International Nuclear Information System (INIS)

In 4??-? coincidence measurement of radioactivity, efficiency extrapolation method has been applied for a long time. According to the principle developed by P. J. Campion, usually a single gamma window is selected, and also an useful assumption is introduced that efficiency of individual ?-branch are linearly related to one another, resulting in a simply linear efficiency function. Generally, the extrapolation curve is not linear so in practice an unspecified efficiency function which is usually defined simply as a polynomial in Nc/N? is introduced. Because of the unspecification of the efficiency function, systematic errors may arise theoretically from which the polynominal function is either inaccurate or unsuitable for extrapolation. To solve this problem, a new method, which is called multi-gamma windows coincidence method is proposed, and a new linear extrapolation equation based on average ? efficiency is strictly derived from the basic coincidence equations with the least approximation. Theoretically, this method is applicable to any simple or complex decay (except pure ? decay and some decay with long life metastable energy level) with minimum systematic errors

1998-01-01

339

Mathematical methods for physical and analytical chemistry

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

340

Transport equation solving methods

International Nuclear Information System (INIS)

[en] This work is mainly devoted to Csub(N) and Fsub(N) methods. CN method: starting from a lemma stated by Placzek, an equivalence is established between two problems: the first one is defined in a finite medium bounded by a surface S, the second one is defined in the whole space. In the first problem the angular flux on the surface S is shown to be the solution of an integral equation. This equation is solved by Galerkin's method. The Csub(N) method is applied here to one-velocity problems: in plane geometry, slab albedo and transmission with Rayleigh scattering, calculation of the extrapolation length; in cylindrical geometry, albedo and extrapolation length calculation with linear scattering. Fsub(N) method: the basic integral transport equation of the Csub(N) method is integrated on Case's elementary distributions; another integral transport equation is obtained: this equation is solved by a collocation method. The plane problems solved by the Csub(N) method are also solved by the Fsub(N) method. The Fsub(N) method is extended to any polynomial scattering law. Some simple spherical problems are also studied. Chandrasekhar's method, collision probability method, Case's method are presented for comparison with Csub(N) and Fsub(N) methods. This comparison shows the respective advantages of the two methods: a) fast convergence and possible extension to various geometries for Csub(N) method; b) easy calculations and easy extension to polynomial scattering for Fsub(N) method[fr] Dans cette these sont etudiees principalement les methodes Csub(N) et Fsub(N). Methode Csub(N): par un lemme du a Placzek, on etablit une equivalence entre un probleme defini dans un volume limite par une surface S et un probleme defini dans tout l'espace. On obtient ainsi une equation integrale dont la solution est le flux angulaire sur la frontiere S, la variable d'espace n'apparaissant pas. On resout cette equation par une methode de Galerkin. En geometrie plane, cette methode est appliquee en theorie monocinetique avec loi de diffusion de Rayleigh a des calculs d'albedo, de facteur de transmission et de longueur d'extrapolation. En geometrie cylindrique, on etudie ces problemes (albedo et longueur d'extrapolation) pour une loi de diffusion lineairement anisotrope. Methode Fsub(N): l'equation integrale servant de base a la methode Csub(N) est integree sur les distributions propres de Case, ce qui conduit a une nouvelle equation integrale, resolue par une methode de collocation. Cette methode est appliquee aux memes problemes que ceux traites par la methode Csub(N) en geometrie plane; on la generalise aussi a une loi de diffusion polynomiale quelconque (geometrie plane) et a des problemes simples en geometrie spherique (diffusion isotrope). Les methodes de Chandrasekhar, des probabilites de collision, des distributions propres de Case sont presentees egalement pour comparaison avec les methodes Csub(N) et Fsub(N). Cette comparaison permet de mettre en evidence les avantages respectifs de la methode Csub(N) (rapidite de convergence, generalisation possible a diverses geometries) et de la methode Fsub(N) (facilite de mise en oeuvre, generalisation facile a des lois de diffusion polynomiales)

1984-01-01

341

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.

2010-01-01

342

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

343

UK PubMed Central (United Kingdom)

Challenges to improve toxicological risk assessment to meet the demands of the EU chemical's legislation, REACH, and the EU 7(th) Amendment of the Cosmetics Directive have accelerated the development of non-animal based methods. Unfortunately, uncertainties remain surrounding the power of alternative methods such as in vitro assays to predict in vivo dose-response relationships, which impedes their use in regulatory toxicology. One issue reviewed here, is the lack of a well-defined dose metric for use in concentration-effect relationships obtained from in vitro cell assays. Traditionally, the nominal concentration has been used to define in vitro concentration-effect relationships. However, chemicals may differentially and non-specifically bind to medium constituents, well plate plastic and cells. They may also evaporate, degrade or be metabolized over the exposure period at different rates. Studies have shown that these processes may reduce the bioavailable and biologically effective dose of test chemicals in in vitro assays to levels far below their nominal concentration. This subsequently hampers the interpretation of in vitro data to predict and compare the true toxic potency of test chemicals. Therefore, this review discusses a number of dose metrics and their dependency on in vitro assay setup. Recommendations are given on when to consider alternative dose metrics instead of nominal concentrations, in order to reduce effect concentration variability between in vitro assays and between in vitro and in vivo assays in toxicology.

Groothuis FA; Heringa MB; Nicol B; Hermens JL; Blaauboer BJ; Kramer NI

2013-08-01

344

Energy Technology Data Exchange (ETDEWEB)

Concentrations and organ distribution patterns of alpha-emitting isotopes of U (238U and 234U), Th (232Th, 230Th, and 228Th), and Pu (239,240Pu) were determined for beagle dogs of our colony. The dogs were exposed to environmental levels of U and Th isotopes through ingestion (food and water) and inhalation to stimulate environmental exposures of the general human population. The organ distribution patterns of these radionuclides in beagles are compared to patterns in humans to determine if it is appropriate to extrapolate organ content data from beagles to humans. The results indicated that approximately 80% of the U and Th accumulated in bone in both species. The organ content percentages of these radionuclides in soft tissues such as liver, kidney, etc. of both species were comparable. The human lung contained higher percentages of U and Th than the beagle lung, perhaps because the longer life span of humans resulted in a longer exposure time. If the U and Th content of dog lung is normalized to an exposure time of 58 y and 63 y, median ages of the U and Th study populations, respectively, the lung content for both species is comparable. The organ content of 239,240Pu in humans and beagles differed slightly. In the beagle, the liver contained more than 60%, and the skeleton contained less than 40% of the Pu body content. In humans, the liver contained approximately 37%, and the skeleton contained approximately 58% of the body 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.

Singh, N.P.; Wrenn, M.E. (Univ. of Utah, Salt Lake City (USA))

1989-01-01

345

UK PubMed Central (United Kingdom)

We investigated if the chronic zinc biotic ligand model (BLM) developed earlier for the arthropod Daphnia magna could be extrapolated to predict chronic ecotoxicity of zinc as a function of water chemistry to two species from other phyla, i.e. the mollusc Lymnaea stagnalis and the rotifer Brachionus calyciflorus. We chronically exposed these two species to zinc in six natural surface waters. These water covered a wide range of pH (6.8-8.3), dissolved organic carbon (1.2-12.7mg/L) and Ca (8.8-118mg/L). Across all waters tested, the 28d-EC10s (200-1629?g Zn/L) and EC50s (382-2026?g Zn/L) for L. stagnalis spanned a 8.1-fold and 5.3-fold range, respectively. The 2d-EC10s (142-550?g Zn/L) and 2d-EC50s (195-1104?g Zn/L) for B. calyciflorus spanned a 3.9-fold and 5.7-fold range, respectively. The data indicated that higher pH and higher concentrations of Ca and DOC were generally associated with lower toxicity (higher ECx values). Furthermore, the chronic Zn BLM for D. magna, when calibrated only to reflect the intrinsic sensitivity of L. stagnalis and B. calyciflorus, was able to predict all ECx values with a less than 1.6-fold error, which demonstrates that the chronic D. magna Zn BLM can be extrapolated to other invertebrate phyla. This lends further support to the use of the chronic Zn BLM to account for bioavailability of zinc in aquatic risk assessment and the derivation of environmental quality standards.

De Schamphelaere KA; Janssen CR

2010-10-01

346

We examined the effects of summer warmth on leaf area index (LAI), total aboveground phytomass (TAP), and normalized difference vegetation index (NDVI) across the Arctic bioclimate zone in Alaska and extrapolated our results to the circumpolar Arctic. Phytomass, LAI, and within homogeneous areas of vegetation on acidic and nonacidic soils were regressed against the total summer warmth index (SWI) at 12 climate stations in northern Alaska (SWI = sum of mean monthly temperatures greater than 0°C). SWI varies from 9°C at Barrow to 37°C at Happy Valley. A 5°C increase in the SWI is correlated with about a 120 g m-2 increase in the aboveground phytomass for zonal vegetation on acidic sites and about 60 g m-2 on nonacidic sites. Shrubs account for most of the increase on acidic substrates, whereas mosses account for most of the increase on nonacidic soils. LAI is positively correlated with SWI on acidic sites but not on nonacidic sites. The NDVI is positively correlated with SWI on both acidic and nonacidic soils, but the NDVI on nonacidic parent material is consistently lower than the NDVI on acidic substrates. Extrapolation to the whole Arctic using a five-subzone zonation approach to stratify the circumpolar NDVI and phytomass data showed that 60% of the aboveground phytomass is concentrated in the low-shrub tundra (subzone 5), whereas the high Arctic (subzones 1-3) has only 9% of the total. Estimated phytomass densities in subzones 1-5 are 47, 256, 102, 454, and 791 g m-2, respectively. Climate warming will likely result in increased phytomass, LAI, and NDVI on zonal sites. These changes will be most noticeable in acidic areas with abundant shrub phytomass.

Walker, D. A.; Epstein, H. E.; Jia, G. J.; Balser, A.; Copass, C.; Edwards, E. J.; Gould, W. A.; Hollingsworth, J.; Knudson, J.; Maier, H. A.; Moody, A.; Raynolds, M. K.

2003-01-01

347

UK PubMed Central (United Kingdom)

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.

Martin BT; Jager T; Nisbet RM; Preuss TG; Hammers-Wirtz M; Grimm V

2013-04-01

348

We present the details of predicting atmospheric turbulence by mining Zernike moment data obtained from simulations as well as experiments. Temporally correlated optical wave-fronts were simulated such that they followed Kolmogorov phase statistics. The wave-fronts reconstructed either by modal or zonal methods can be represented in terms of Zernike moments. The servo lag error in adaptive optics is minimized by predicting Zernike moments in the near future by using the data from the immediate past. It is shown statistically that the prediction accuracy depends on the number of past phase screens used for prediction and servo lag time scales. The algorithm is optimized in terms of these parameters for real time and efficient operation of the adaptive optics system. On an average, we report more than 3% improvement in the wave-front compensation after prediction. This analysis helps in optimizing the design parameters for sensing and correction in closed loop adaptive optics systems.

Vyas, Akondi; Prasad, B Raghavendra

2010-01-01

349

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.

2001-04-19

350

UK PubMed Central (United Kingdom)

BACKGROUND: Male circumcision (MC) has been shown to reduce the risk of HIV acquisition among heterosexual men, with WHO recommending MC as an essential component of comprehensive HIV prevention programs in high prevalence settings since 2007. While Papua New Guinea (PNG) has a current prevalence of only 1%, the high rates of sexually transmissible diseases and the extensive, but unregulated, practice of penile cutting in PNG have led the National Department of Health (NDoH) to consider introducing a MC program. Given public interest in circumcision even without active promotion by the NDoH, examining the potential health systems implications for MC without raising unrealistic expectations presents a number of methodological issues. In this study we examined health systems lessons learned from a national no-scalpel vasectomy (NSV) program, and their implications for a future MC program in PNG. METHODS: Fourteen in-depth interviews were conducted with frontline health workers and key government officials involved in NSV programs in PNG over a 3-week period in February and March 2011. Documentary, organizational and policy analysis of HIV and vasectomy services was conducted and triangulated with the interviews. All interviews were digitally recorded and later transcribed. Application of the WHO six building blocks of a health system was applied and further thematic analysis was conducted on the data with assistance from the analysis software MAXQDA. RESULTS: Obstacles in funding pathways, inconsistent support by government departments, difficulties with staff retention and erratic delivery of training programs have resulted in mixed success of the national NSV program. CONCLUSIONS: In an already vulnerable health system significant investment in training, resources and negotiation of clinical space will be required for an effective MC program. Focused leadership and open communication between provincial and national government, NGOs and community is necessary to assist in service sustainability. Ensuring clear policy and guidance across the entire sexual and reproductive health sector will provide opportunities to strengthen key areas of the health system.

Tynan A; Vallely A; Kelly A; Law G; Millan J; Siba P; Kaldor J; Hill PS

2012-01-01

351

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Male circumcision (MC) has been shown to reduce the risk of HIV acquisition among heterosexual men, with WHO recommending MC as an essential component of comprehensive HIV prevention programs in high prevalence settings since 2007. While Papua New Guinea (PNG) has a current prevalence of only 1%, the high rates of sexually transmissible diseases and the extensive, but unregulated, practice of penile cutting in PNG have led the National Department of Health (NDoH) to consider introducing a MC program. Given public interest in circumcision even without active promotion by the NDoH, examining the potential health systems implications for MC without raising unrealistic expectations presents a number of methodological issues. In this study we examined health systems lessons learned from a national no-scalpel vasectomy (NSV) program, and their implications for a future MC program in PNG. Methods Fourteen in-depth interviews were conducted with frontline health workers and key government officials involved in NSV programs in PNG over a 3-week period in February and March 2011. Documentary, organizational and policy analysis of HIV and vasectomy services was conducted and triangulated with the interviews. All interviews were digitally recorded and later transcribed. Application of the WHO six building blocks of a health system was applied and further thematic analysis was conducted on the data with assistance from the analysis software MAXQDA. Results Obstacles in funding pathways, inconsistent support by government departments, difficulties with staff retention and erratic delivery of training programs have resulted in mixed success of the national NSV program. Conclusions In an already vulnerable health system significant investment in training, resources and negotiation of clinical space will be required for an effective MC program. Focused leadership and open communication between provincial and national government, NGOs and community is necessary to assist in service sustainability. Ensuring clear policy and guidance across the entire sexual and reproductive health sector will provide opportunities to strengthen key areas of the health system.

Tynan Anna; Vallely Andrew; Kelly Angela; Law Greg; Millan John; Siba Peter; Kaldor John; Hill Peter S

2012-01-01

352

International Nuclear Information System (INIS)

[en] The austenitic stainless steel X6CrNi1811 (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 550-6500C under base material condition as well as welded material condition. The main point of this program ('Extrapolation-Program') lies in the knowledge of the creep-rupture-strength and creep-behaviour up to 3 x 104 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 of 5500C - 7500C. The present report describes the state in the running program with test-times up to 35.000 hours. Besides the creep-rupture behaviour it is possible to make a distinct quantitativ statement for the creep-behaviour and ductility. Extensive metallographic examinations show the fracture behaviour and changes in structure. (orig.)[de] An den austenitischen Stahl X6CrNi 1811 (DIN 1.4948), der als Anlagenstrukturwerkstoff im ersten deutschen Schnell-Brueter-Reakter SNR 300 verwendet wird, werden im Temperaturbereich 550-6500C Zeitstandversuche an Grundmaterial und geschweisstem Material durchgefuehrt. Der Schwerpunkt dieses Versuchsprogrammes ('Extrapolationsprogramm') liegt bei der experimentellen Erfassung des Zeitstandfestigkeits- und Kriechverhaltens bis 3 . 104 Stunden bei hoeheren Temperaturen, um auf das Werkstoffverhalten bis >= 105 std bei Betriebstemperaturen extrapolieren zu koennen. In einem weiteren Programmteil werden am Grundwerkstoff im Temperaturbereich 550-7500C zusaetzliche Versuche gefahren, zur Erfassung der Spannungsabhaengigkeit der minimalen Kriechgeschwindigkeit. Der vorliegende Bericht beschreibt den bisherigen Stand der Arbeiten mit Versuchszeiten bis zu 16.000 std und nimmt Bezug auf Ergebnisse bis zu rund 35.000 std an diesem Stahl aus anderen Programmteilen. Neben dem Zeitstandfestigkeitsverhalten lassen sich fuer 550-7500C klare quantitative Aussagen zum Kriechverhalten und zur Duktilitaet machen. Umfangreiche metallographische Untersuchungen geben Aufschluss ueber das Bruchverhalten und strukturelle Aenderungen. (orig.)

1978-01-01

353

-D data infill and extrapolation

UK PubMed Central (United Kingdom)

Here I deal with data given on a uniform 3-D mesh (or 1-D or 2-D). I providecode for recovering missing data in the interior of the cube or abutting one wallof the 3-D data cube by a two-stage linear least squares process. First I fit a 3-Dprediction-error filter (PEF) to the extended cube ignoring regression equationsthat involve missing elements. Then I estimate those missing elements by findingthe data that minimizes the power out of the PEF. As in my other work sinceSEP-73, the volume can be broken into subcubes in which separate problems aresolved and pieced together.INTRODUCTIONGeophysicists have known for many years how to compute the prediction-error filter(PEF) for a time series. Given a prediction filter, it is fairly obvious how to extrapolatethe signal beyond its ends or how to fill in gaps. (Classical theory focuses oninstabilities that can arise, but these instabilities do not arise when using the methodsfound in my recent book (Claerbout, 1992), cha...

Jon F. Claerbout

354

Cancer dose-response extrapolations

Energy Technology Data Exchange (ETDEWEB)

Quantitative dose-response modeling is an important contributor to cancer risk assessment; hence, it is a major factor in cancer risk management and the regulatory process. The dose-response models now used in the regulatory process are overly simplistic, probabilistic representations of highly complex biological phenomena; these models are not biological models. Several of these simplistic models provide similar fits to the high-dose data generated in chronic animal bioassays but provide dissimilar projections of risk at the lower doses of interest to man. The possibilities for the low-dose behavior of a simplistic model can be so independent of the fit of that model to the experimental data that an upper confidence limit, or upper bound, on the risk at a low dose can be orders of magnitude larger than the fitted model. The potency measures, such as unit risks and relative risks, cited by the regulatory agencies are based on upper bounds and not on fitted model values. These measurements do not differentiate between carcinogens on the basis of available experimental data about the shapes of the dose-response relationship. In order to obtain more useful quantitative dose-response assessments, the plethora of simplistic models must be replaced by more biologically reflective dose-response models that utilize the available scientific information. New dose-response modeling techniques can incorporate representations of the exposure in terms of dose scales based on cell turnover rates, repair processes, immune system responses, and physiological and pharmacokinetic models of the absorption, delivery, metabolism, and elimination of chemicals.

Sielken, R.L. Jr.

1987-11-01

355

Double error mode extrapolation procedure

Energy Technology Data Exchange (ETDEWEB)

A procedure is described for removing two error vectors from the approximation to the solution obtained iteratively. Such a scheme for accelerating convergence can reduce the computation cost of solving neutronics problems as is demonstrated for finite difference diffusion theory. 7 refs.

Vondy, D.R.; Fowler, T.B.

1982-01-01

356

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese OBJETIVO: Conhecer o perfil de pacientes adultos com bronquiectasias, comparando portadores de fibrose cística (FC) com aqueles com bronquiectasias de outra etiologia, a fim de determinar se é racional extrapolar terapêuticas instituídas em fibrocísticos para aqueles com bronquiectasias de outras etiologias. MÉTODOS: Análise retrospectiva dos prontuários de 87 pacientes adultos com diagnóstico de bronquiectasia em acompanhamento em nosso serviço. Pacientes com d (more) oença secundária a infecção por tuberculose corrente ou no passado foram excluídos. Foram avaliados dados clínicos, funcionais e terapêuticos dos pacientes. RESULTADOS: Dos 87 pacientes com bronquiectasias, 38 (43,7%) tinham diagnóstico confirmado de FC através de dosagem de sódio e cloro no suor ou análise genética, enquanto 49 (56,3%) apresentavam a doença por outra etiologia, 34 (39,0%) desses com bronquiectasia idiopática. Os pacientes com FC apresentavam média de idade ao diagnóstico mais baixa (14,2 vs. 24,2 anos; p Abstract in english OBJECTIVE: To profile the characteristics of adult patients with bronchiectasis, drawing comparisons between cystic fibrosis (CF) patients and those with bronchiectasis from other causes in order to determine whether it is rational to extrapolate the bronchiectasis treatment given to CF patients to those with bronchiectasis from other causes. METHODS: A retrospective analysis of the medical charts of 87 patients diagnosed with bronchiectasis and under follow-up treatment (more) at our outpatient clinic. Patients who had tuberculosis (current or previous) were excluded. We evaluated the clinical, functional, and treatment data of the patients. RESULTS: Of the 87 patients with bronchiectasis, 38 (43.7%) had been diagnosed with CF, through determination of sweat sodium and chloride concentrations or through genetic analysis, whereas the disease was due to another etiology in 49 (56.3%), of whom 34 (39.0%) had been diagnosed with idiopathic bronchiectasis. The mean age at diagnosis was lower in the patients with CF than in those without (14.2 vs. 24.2 years; p

Athanazio, Rodrigo Abensur; Rached, Samia Zahi; Rohde, Ciro; Pinto, Regina Carvalho; Fernandes, Frederico Leon Arrabal; Stelmach, Rafael

2010-08-01

357

UK PubMed Central (United Kingdom)

OBJECTIVES: This study aimed to characterize the effects of bovine serum albumin (BSA) on the kinetics of CYP2C8-catalyzed paclitaxel 6?-hydroxylation in vitro; determine whether the addition of BSA to incubations improves the prediction of paclitaxel hepatic clearance via this pathway in vivo; and assess interindividual variability in predicted clearance. METHODS: The kinetics of paclitaxel 6?-hydroxlation by human liver microsomes (HLM) and recombinant CYP2C8 were characterized in incubations performed with and without BSA (2% w/v) supplementation, and the in vitro kinetic data were extrapolated to provide estimates of in vivo clearances. The Simcyp population-based ADME simulator was used to determine interindividual variability in the predicted clearances. RESULTS: Supplementation of incubations of HLM with BSA resulted in a 3.6-fold increase in the microsomal intrinsic clearance for paclitaxel 6?-hydroxylation, due mainly to a reduction in K(m) (7.08?±?2.50 to 2.26?±?0.39 ?M), while addition of BSA to incubations of recombinant CYP2C8 resulted in an approximate doubling of intrinsic clearance. Mean values of predicted in vivo hepatic clearance were in good agreement with clinical data when in vitro data obtained in the presence of BSA were used for IV-IVE. Simcyp predicted 20- to 30-fold interindividual variability in in vivo paclitaxel hepatic clearance via the 6?-hydroxylation pathway. CONCLUSIONS: Human liver microsomal K(m) and intrinsic clearance values are over- and underpredicted, respectively, when incubations of the CYP2C8 substrate paclitaxel are performed without BSA supplementation. IV-IVE based on kinetic parameters generated in the presence of BSA improves the accuracy of predicted paclitaxel hepatic clearance.

Wattanachai N; Polasek TM; Heath TM; Uchaipichat V; Tassaneeyakul W; Tassaneeyakul W; Miners JO

2011-08-01

358

Introduction: Predicting the pharmacokinetics (PK) of prodrugs and their corresponding active drugs is challenging, as there are many variables to consider. Prodrug conversion characteristics in different tissues are generally measured, but integrating these variables to a PK profile is not a common practice. In this paper, a joined in vitro/in silico-in vivo extrapolation (IVIVE) and physiologically-based pharmacokinetic (PBPK) modeling approach is presented to predict active drug exposure in human after oral prodrug administration. Methods: Physico-chemical and in vitro assays as well as in silico predictions were proposed to characterize key pharmacokinetic properties (e.g. clearance, volume of distribution, conversion rates) of three marketed prodrugs. These data were used to parameterize a PBPK model for simulating human PK profiles of the active drugs after prodrug administration, which were compared to literature data by evaluating the accuracy and uncertainty of the predictions. Results: For mycophenate mofetil and midodrine the PK of their active moieties could be adequately predicted. The assumptions of the PBPK-IVIVE approach were valid, i.e. being hepatically cleared, converted in the gut lumen, blood and liver and not metabolized in the gut wall. However, the observed profiles after oral bambuterol administration clearly fell outside the prediction interval as the PBPK model failed to predict the observed bioavailability. Discussion: Adding quantitative information about prodrug conversion in the gut, liver and blood to a PBPK model for the absorption, distribution, metabolism and excretion (ADME) properties of prodrugs and their active moieties resulted, retrospectively, in reasonable predictions of the human PK when the ADME properties are well understood. Also in a prospective compound selection process, this integrative approach can improve decision making on prodrug candidates by putting relative differences in prodrug conversion of a large number of candidates into the perspective of their human PK profile, before conducting any in vivo experiments. PMID:23280406

Malmborg, Jonas; Ploeger, Bart A

2012-12-29

359

UK PubMed Central (United Kingdom)

Introduction: Predicting the pharmacokinetics (PK) of prodrugs and their corresponding active drugs is challenging, as there are many variables to consider. Prodrug conversion characteristics in different tissues are generally measured, but integrating these variables to a PK profile is not a common practice. In this paper, a joined in vitro/in silico-in vivo extrapolation (IVIVE) and physiologically-based pharmacokinetic (PBPK) modeling approach is presented to predict active drug exposure in human after oral prodrug administration. Methods: Physico-chemical and in vitro assays as well as in silico predictions were proposed to characterize key pharmacokinetic properties (e.g. clearance, volume of distribution, conversion rates) of three marketed prodrugs. These data were used to parameterize a PBPK model for simulating human PK profiles of the active drugs after prodrug administration, which were compared to literature data by evaluating the accuracy and uncertainty of the predictions. Results: For mycophenate mofetil and midodrine the PK of their active moieties could be adequately predicted. The assumptions of the PBPK-IVIVE approach were valid, i.e. being hepatically cleared, converted in the gut lumen, blood and liver and not metabolized in the gut wall. However, the observed profiles after oral bambuterol administration clearly fell outside the prediction interval as the PBPK model failed to predict the observed bioavailability. Discussion: Adding quantitative information about prodrug conversion in the gut, liver and blood to a PBPK model for the absorption, distribution, metabolism and excretion (ADME) properties of prodrugs and their active moieties resulted, retrospectively, in reasonable predictions of the human PK when the ADME properties are well understood. Also in a prospective compound selection process, this integrative approach can improve decision making on prodrug candidates by putting relative differences in prodrug conversion of a large number of candidates into the perspective of their human PK profile, before conducting any in vivo experiments.

Malmborg J; Ploeger BA

2013-05-01

360

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

361

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La corrosión de recipientes fabricados en hojalata expuestos a diferentes soluciones fue evaluada usando técnicas eletroquímicas. Los recipientes con y sin la aplicación de barniz fueron expuestos a diferentes soluciones. La susceptibilidad a sufrir corrosión se evaluó utilizando voltametría cíclica, curvas de polarización y espectroscopia de impedancia electroquímica. La posibilidad de formación de películas pasivas en la superfi cie de los recipientes se eva (more) luó según la histéresis presente en el primer ciclo de las medidas de voltametría. Las curvas de polarización revelaron que el comportamiento del recubrimiento de estaño puede cambiar de anódico a catódico según la naturaleza de la solución en contacto con el recipiente, alertando sobre el riesgo de corrosión localizada. Mediante impedancia electroquímica se evaluó el efecto del uso de un aditivo en las soluciones o productos empacados en dos recipientes. Las medidas de impedancia mostraron un efecto perjudicial del aditivo utilizado y una rápida aparición de procesos corrosivos cuando se usó la solución modifi cada con el aditivo. Abstract in english Corrosion of lacquered tinplate cans in different solutions was assessed using electrochemical methods. Samples with and without lacquer coating were exposed to different solutions and their susceptibility to corrosion was evaluated using cyclic voltammetry, Tafel curves and electrochemical impedance spectroscopy. The possible formation of a passive layer on the container surface was evaluated according to the kind of hysteresis presented in the fi rst cycle of voltammete (more) r measurements. Tafel plots showed how the behaviour of the tin layer can change from anodic to cathodic depending on the nature of the solution in contact with it, revealing the risk of localized corrosion. The effect of one additive in the solutions on the electrochemical performance containers was evaluated by electrochemical impedance. The impedance showed a deleterious effect of the additive, and corrosion processes appeared more quickly in containers packed with solutions modifi ed with additive.

Calderón, Jorge A; Buitrago, Carmen P

2007-12-01

362

Organic anion-transporting polypeptides (OATP) 1B1, 1B3, and 2B1 can serve as the loci of drug-drug interactions (DDIs). In the present work, the cynomolgus monkey was evaluated as a potential model for studying OATP-mediated DDIs. Three cynomolgus monkey OATPs (cOATPs), with a high degree of amino acid sequence identity (91.9, 93.5, and 96.6% for OATP1B1, 1B3, and 2B1, respectively) to their human counterparts, were cloned, expressed, and characterized. The cOATPs were stably transfected in human embryonic kidney cells and were functionally similar to the corresponding human OATPs (hOATPs), as evident from the similar uptake rate of typical substrates (estradiol-17?-d-glucuronide, cholecystokinin octapeptide, and estrone-3-sulfate). Moreover, six known hOATP inhibitors exhibited similar IC(50) values against cOATPs. To further evaluate the appropriateness of the cynomolgus monkey as a model, a known hOATP substrate [rosuvastatin (RSV)]-inhibitor [rifampicin (RIF)] pair was examined in vitro; the monkey-derived parameters (RSV K(m) and RIF IC(50)) were similar (within 3.5-fold) to those obtained with hOATPs and human primary hepatocytes. In vivo, the area under the plasma concentration-time curve of RSV (3 mg/kg, oral) given 1 hour after a single RIF dose (15 mg/kg, oral) was increased 2.9-fold in cynomolgus monkeys, consistent with the value (3.0-fold) reported in humans. A number of in vitro-in vivo extrapolation approaches, considering the fraction of the pathways affected and free versus total inhibitor concentrations, were also explored. It is concluded that the cynomolgus monkey has the potential to serve as a useful model for the assessment of OATP-mediated DDIs in a nonclinical setting. PMID:23297161

Shen, Hong; Yang, Zheng; Mintier, Gabe; Han, Yong-Hae; Chen, Cliff; Balimane, Praveen; Jemal, Mohammed; Zhao, Weiping; Zhang, Renjie; Kallipatti, Sanjith; Selvam, Sabariya; Sukrutharaj, Sunil; Krishnamurthy, Prasad; Marathe, Punit; Rodrigues, A David

2013-01-07

363

UK PubMed Central (United Kingdom)

Organic anion-transporting polypeptides (OATP) 1B1, 1B3, and 2B1 can serve as the loci of drug-drug interactions (DDIs). In the present work, the cynomolgus monkey was evaluated as a potential model for studying OATP-mediated DDIs. Three cynomolgus monkey OATPs (cOATPs), with a high degree of amino acid sequence identity (91.9, 93.5, and 96.6% for OATP1B1, 1B3, and 2B1, respectively) to their human counterparts, were cloned, expressed, and characterized. The cOATPs were stably transfected in human embryonic kidney cells and were functionally similar to the corresponding human OATPs (hOATPs), as evident from the similar uptake rate of typical substrates (estradiol-17?-d-glucuronide, cholecystokinin octapeptide, and estrone-3-sulfate). Moreover, six known hOATP inhibitors exhibited similar IC(50) values against cOATPs. To further evaluate the appropriateness of the cynomolgus monkey as a model, a known hOATP substrate [rosuvastatin (RSV)]-inhibitor [rifampicin (RIF)] pair was examined in vitro; the monkey-derived parameters (RSV K(m) and RIF IC(50)) were similar (within 3.5-fold) to those obtained with hOATPs and human primary hepatocytes. In vivo, the area under the plasma concentration-time curve of RSV (3 mg/kg, oral) given 1 hour after a single RIF dose (15 mg/kg, oral) was increased 2.9-fold in cynomolgus monkeys, consistent with the value (3.0-fold) reported in humans. A number of in vitro-in vivo extrapolation approaches, considering the fraction of the pathways affected and free versus total inhibitor concentrations, were also explored. It is concluded that the cynomolgus monkey has the potential to serve as a useful model for the assessment of OATP-mediated DDIs in a nonclinical setting.

Shen H; Yang Z; Mintier G; Han YH; Chen C; Balimane P; Jemal M; Zhao W; Zhang R; Kallipatti S; Selvam S; Sukrutharaj S; Krishnamurthy P; Marathe P; Rodrigues AD

2013-03-01

364

Proton NMR studies at 360 MHz were carried out on the trinucleoside diphosphate dApdApdA, the dinucleoside monophosphate dApdA and the methylphosphate esters of the monomers pdA, pdAp and dAp. The compounds were also investigated by means of circular dichroism at varying temperatures. Complete NMR spectral assignments are given. The thermodynamics of stacking derived from the circular dichroic spectra was used to extrapolate the observed coupling constants, measured at a range of temperatures, to values appropriate to the pure stacked states of the dimer and the trimer. The data were interpreted in terms of the N and S deoxyribose pseudorotational ranges [Altona, C. and Sundaralingam, M. (1972) J. Am. Chem. Soc. 94, 8205--8212] and it is shown that the right-handed single helix of the trimer occurs in two distinct forms: the major one corresponds to a B-DNA-like structure, S-S-S; the minor one (30%) has the sugar rings in a hitherto unsuspected S-S-N conformational sequence. The dimer behaves quite similarly, a mixture of 70% S-S and 30% S-N stacks being indicated. The detailed geometry of teh S-type sugar rings is not invariable but appears to undergo a slight shift when another base stacks on top of a given nucleotide unit. The backbone angles of the fully stacked B-DNA-like single helix in solution are (starting the notation at P) beta = 187 degrees, gamma = 50 degrees, delta = 138 degrees, epsilon = 186 degrees. PMID:6935052

Olsthoorn, C S; Bostelaar, L J; Van Boom, J H; Altona, C

1980-11-01

365

UK PubMed Central (United Kingdom)

The beagle dog is a widely used in vivo model to guide clinical formulation development and to explore the potential for food effects. However, the results in dogs are often not directly translatable to humans. Consequently, a physiologically based modeling strategy has been proposed, using the dog as a validation step to verify model assumptions before making predictions in humans. One current weakness in this strategy is the lack of validated tools to incorporate gut wall metabolism into the dog model. In this study, in vitro to in vivo extrapolation factors for CYP2B11 and CYP3A12 mediated metabolism were established based on tissue enzyme abundance data reported earlier. Thereafter, physiologically based modeling of intestinal absorption in beagle dog was conducted in GastroPlus using V(max) and K(m) determined in recombinant enzymes as inputs for metabolic turnover. The predicted fraction of absorbed dose escaping the gut wall metabolism (F(g)) of all five reference compounds studied (domperidone, felodipine, nitrendipine, quinidine, and sildenafil) were within a two-fold range of the value estimated from in vivo data at single dose levels. However, further in vivo studies and analysis of the dose-dependent pharmacokinetics of felodipine and nitrendipine showed that more work is required for robust forecasting of nonlinearities. In conclusion, this study demonstrates an approach for prediction of the gut wall extraction of CYP substrates in the beagle dog, thus enhancing the value of dog studies as a component in a strategy for the prediction of human pharmacokinetics.

Heikkinen AT; Fowler S; Gray L; Li J; Peng Y; Yadava P; Railkar A; Parrott N

2013-04-01

366

Determination of corrosion rate from electrode kinetic measurement

International Nuclear Information System (INIS)

[en] Electrode kinetic measurements provide a valuable technique for determining the corrosion rates of metals. The processes controlled by activation polarization are described by an exponential type of relation involving three unknowns. Corrosion behaviour of a metal can be fully described if these three parameters i.e. corrosion current, Ic and the two Tafel constants Beta/sub a/ and Beta/sub c/ are known. Experimentally the current density is measured as a function of the applied over relationship is such that an accurate determination of the three parameters by Ordinary Least Squares Fit is generally not possible. Various attempts have been made to simplify the equation using approximations. These are reflected in the well known methods such as Tafel Line Extrapolation and Linear Polarization. In Three Point and Four Point methods, selected data points are used which transform the original equation into similar relation such as a quadratic equation. Recently some computer based methods have been developed such as BETACRUNCH in which the method of averages is used. We have developed a new method to analyze experimental polarization data and determine the unknown parameters. We have formulated three independent relationships to solve for Ic, Ba and Beta/sub c/. In addition to the original version we have improved the methods by using some additional numerical approaches. These methods are robust and give accurate determination of Tafel constants and the corrosion current density for a wide range of systems. Using the suggested scheme, it is also possible to avoid data corresponding to very low and very high over potentials and yet obtain excellent results. These methods are less sensitive to experimental errors as compared to other existing methods. (author)

1993-01-01

367

Physical models and numerical methods of the reactor dynamic computer program RETRAN

International Nuclear Information System (INIS)

[en] This report describes the physical models and the numerical methods of the reactor dynamic code RETRAN simulating reactivity transients in Light-Water-Reactors. The neutron-physical part of RETRAN bases on the two-group-diffusion equations which are solved by discretization similar to the TWIGL-method. An exponential transformation is applied and the inner iterations are accelerated by a coarse-mesh-rebalancing procedure. The thermo-hydraulic model approximates the equation of state by a built-in steam-water-table and disposes of options for the calculation of heat-conduction coefficients and heat transfer coefficients. (Author)[de] Der vorliegende Bericht beschreibt die physikalischen Modelle und die numerischen Methoden des reaktordynamischen Codes RETRAN, der Reaktivitaetstransienten in Leichtwasserreaktoren simuliert. Der neutronenphysikalische Teil von RETRAN basiert auf den Zweigruppen-Diffusionsgleichungen, die aehnlich wie bei der TWIGL-Methode durch Diskretisierung geloest werden. Es wird eine Exponentialtransformation angewandt. Die inneren Iterationen werden durch ein Grobmaschenverfahren beschleunigt. Das thermo-hydraulische Modell approximiert die Kuehlmittelzustandsgleichung durch eine eingebaute Dampf-Wasser-Tafel und verfuegt ueber Optionen zur Berechnung der Waermeleitungs- und Waermeuebergangskoeffizienten. (Autor)

1984-01-01

368

On boundary conditions in lattice Boltzmann methods

Energy Technology Data Exchange (ETDEWEB)

A lattice Boltzmann boundary condition for simulation of fluid flow using simple extrapolation is proposed. Numerical simulations, including two-dimensional Poiseuille flow, unsteady Couette flow, lid-driven square cavity flow, and flow over a column of cylinders for a range of Reynolds numbers, are carried out, showing that this scheme is of second order accuracy in space discretization. Applications of the method to other boundary conditions, including pressure condition and flux condition are discussed. {copyright} {ital 1996 American Institute of Physics.}

Chen, S.; Martinez, D. [IBM Research Division, T. J. Watson Research Center, P. O. Box 218, Yorktown Heights, New York 10598 (United States)]|[Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Mei, R. [Department of Aerospace Engineering, Mechanics and Engineering Science, University of Florida, Gainesville, Florida 32611-6250 (United States)

1996-09-01

369

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 < 0.05) the K(m) values of the high-affinity components of human liver microsomal PHEN and LID deethylation by approximately 70%, without affecting V(max). The K(m) (or S(50)) values for PHEN and LID deethylation by rCYP1A2 were reduced to a similar extent. A fatty 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

2012-02-13

370

UK PubMed Central (United Kingdom)

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 < 0.05) the K(m) values of the high-affinity components of human liver microsomal PHEN and LID deethylation by approximately 70%, without affecting V(max). The K(m) (or S(50)) values for PHEN and LID deethylation by rCYP1A2 were reduced to a similar extent. A fatty 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.

Wattanachai N; Tassaneeyakul W; Rowland A; Elliot DJ; Bowalgaha K; Knights KM; Miners JO

2012-05-01

371

Configuration interaction (CI) methods, which rely on diagonalizing the Hamiltonian within a basis, are often used to develop a fully microscopic description for quantum many-body systems. CI methods, however, are limited in their applicability because the basis dimension grows dramatically with particle number. Since the computational effort for the Auxiliary-field Monte Carlo (AFMC) method scales more gently with particle number, it is a natural approach for large-scale problems. But, AFMC is often crippled by the notorious sign problem, which essentially makes the Monte Carlo sampling impossible. The sign problem substantially limits the efficacy of the AFMC method, and has limited nuclear applications to only even-particle systems with simple schematic interactions or the extrapolation method. We report a novel, but straightforward, solution to the sign problem: the shifted-contour method. We show exact results for sd- and fp-shell nuclei with fully realistic interactions without reliance on extrapolations.

Stoitcheva, Gergana; Ormand, Erich

2007-10-01

372

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

373

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

374

The factorization method for Monte Carlo simulations of systems with a complex action

Energy Technology Data Exchange (ETDEWEB)

We propose a method for Monte Carlo simulations of systems with a complex action. The method has the advantages of being in principle applicable to any such system and provides a solution to the overlap problem. In some cases, like in the IKKT matrix model, a finite size scaling extrapolation can provide results for systems whose size would make it prohibitive to simulate directly.

Ambjoern, J.; Anagnostopoulos, K.N.; Nishimura, J.; Verbaarschot, J.J.M

2004-03-01

375

The Factorization Method for Monte Carlo Simulations of Systems With a Complex Action

We propose a method for Monte Carlo simulations of systems with a complex action. The method has the advantages of being in principle applicable to any such system and provides a solution to the overlap problem. In some cases, like in the IKKT matrix model, a finite size scaling extrapolation can provide results for systems whose size would make it prohibitive to simulate directly.

Ambjørn, Jan; Nishimura, J; Verbaarschot, J J M

2004-01-01

376

The factorization method for Monte Carlo simulations of systems with a complex action

International Nuclear Information System (INIS)

We propose a method for Monte Carlo simulations of systems with a complex action. The method has the advantages of being in principle applicable to any such system and provides a solution to the overlap problem. In some cases, like in the IKKT matrix model, a finite size scaling extrapolation can provide results for systems whose size would make it prohibitive to simulate directly.

2004-01-01

377

Extended local Rytov Fourier migration method

Energy Technology Data Exchange (ETDEWEB)

The authors develop a novel depth-migration method termed the extended local Rytov Fourier (ELRF) migration method. It is based on the scalar wave equation and a local application of the Rytov approximation within each extrapolation interval. Wavefields are Fourier transformed back and forth between the frequency-space and frequency-wavenumber domains during wavefield extrapolation. The lateral slowness variations are taken into account in the frequency-space domain. The method is efficient due to the use of a fast Fourier transform algorithm. Under the small angle approximation, the ELRF method leads to the split-step Fourier (SSF) method that is unconditionally stable. The ELRF method and the extended local Born Fourier (ELBF) method that the authors previously developed can handle wider propagation angles than the SSF method and account for the phase and amplitude changes due to the lateral variations of slowness, whereas the SSF method only accounts for the phase changes. The stability of the ELRF method is controlled more easily than that of the ELBF method.

Huang, L.J.; Fehler, M.C.; Roberts, P.M.; Burch, C.C.

1999-10-01

378

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.; Bocchi Nerilso; Rocha-Filho Romeu C.

2000-01-01

379

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 an apparent 4-electron process.

2010-01-01

380

On prestack migration methods for common-offset seismic section

Energy Technology Data Exchange (ETDEWEB)

The authors analyze the geometrical principle of prestack migration methods for common-offset seismic section, and expound the new thinking of prestack full migration method. A wave equation method for prestack full migration is put forward, which is different from DMO method in means and image point position. This method performs in two steps: migrating CDP data with different offsets to their original reflecting positions by making first coordinate system transform then wave equation wavefield extrapolation and stacking the migrated data. This method stands for all dips. The trial result of physical model shows that the wave equation method for prestack full migration is feasible for real seismic data processing.

Zaitian, M.; Jianguo, S

1990-01-01

381

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

382

Digital Repository Infrastructure Vision for European Research (DRIVER)

An in vitro method of detecting synergy which is simple to perform, accurate, and reproducible and has the potential for clinical extrapolation is desirable. Time-kill and checkerboard methods are the most widely used techniques to assess synergy but are time-consuming and labor-intensive. The Epsil...

White, R L; Burgess, D S; Manduru, M; Bosso, J A

383

Improved quasi-steady-state-approximation methods for atmospheric chemistry integration

Energy Technology Data Exchange (ETDEWEB)

In the last fifteen years the quasi-steady-state-approximation (QSSA) method has been a commonly used method for integrating stiff ordinary differential equations arising from atmospheric chemistry problems. In this paper a theoretical analysis of the QSSA method is developed, stressing its strengths and its weaknesses. This theory leads to practical improvements to the QSSA method. New algorithms, including symmetric and extrapolated QSSA are presented.

Jay, L.O. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Computer Science; Sandu, A.; Potra, F.A.; Carmichael, G.R. [Univ. of Iowa, Iowa City, IA (United States)

1997-01-01

384

A method for measuring light ion reaction cross sections

Energy Technology Data Exchange (ETDEWEB)

An experimental procedure for measuring reaction cross sections of light ions in the energy range 20-50 MeV/nucleon, using a modified attenuation technique, is described. The detection method incorporates a forward detector that simultaneously measures the reaction cross sections for five different sizes of the solid angles in steps from 99.1 to 99.8% of the total solid angle. The final reaction cross section values are obtained by extrapolation to the full solid angle.

Carlson, R.F. [Univ. of Redlands, CA (United States). Dept. of Physics; Ingemarsson, A.; Lantz, M. [Uppsala Univ. (Sweden). Dept. of Radiation Sciences] [and others

2005-03-01

385

A Pseudo DNA Cryptography Method

The DNA cryptography is a new and very promising direction in cryptography research. DNA can be used in cryptography for storing and transmitting the information, as well as for computation. Although in its primitive stage, DNA cryptography is shown to be very effective. Currently, several DNA computing algorithms are proposed for quite some cryptography, cryptanalysis and steganography problems, and they are very powerful in these areas. However, the use of the DNA as a means of cryptography has high tech lab requirements and computational limitations, as well as the labor intensive extrapolation means so far. These make the efficient use of DNA cryptography difficult in the security world now. Therefore, more theoretical analysis should be performed before its real applications. In this project, We do not intended to utilize real DNA to perform the cryptography process; rather, We will introduce a new cryptography method based on central dogma of molecular biology. Since this method simulates some critical ...

Ning, Kang

2009-01-01

386

Report on the uncertainty methods study

International Nuclear Information System (INIS)

[en] 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

1998-01-01

387

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

UK PubMed Central (United Kingdom)

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.

Priyada P; Ramar R; Shivaramu

2012-10-01

388

Comparative study among calibration methods of clinical applicators of beta radiation

International Nuclear Information System (INIS)

[en] 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 applicators were studied, comparing the results with those given by the calibration certificates of the manufacturers. The methods included the use of the standard applicator of the Calibration Laboratory (LCI), calibrated by the National Institute of Standards and Technology; an Amersham applicator (LCI) as reference; a mini-extrapolation chamber developed at LCI as an absolute standard; and thermoluminescent dosimetry. The mini-extrapolation chamber and a PTW commercial extrapolation chamber were studied in relation to their performance through quality control tests of their response, as leakage current, repeatability and reproducibility. The distribution of the depth dose in water, that presents high importance in dosimetry of clinical applicators, was determined using the mini extrapolation chamber and the thermoluminescent dosimeters. The results obtained were considered satisfactory for the both cases, and comparable to the data of the IAEA (2002) standard. Furthermore, a dosimetry postal kit was developed for the calibration of clinical applicators using the thermoluminescent technique, to be sent to clinics and hospitals, without the need of the transport of the sources to IPEN for calibration. (author)

2009-01-01

389

On boundary conditions in lattice Boltzmann methods

International Nuclear Information System (INIS)

[en] A lattice Boltzmann boundary condition for simulation of fluid flow using simple extrapolation is proposed. Numerical simulations, including two-dimensional Poiseuille flow, unsteady Couette flow, lid-driven square cavity flow, and flow over a column of cylinders for a range of Reynolds numbers, are carried out, showing that this scheme is of second order accuracy in space discretization. Applications of the method to other boundary conditions, including pressure condition and flux condition are discussed. copyright 1996 American Institute of Physics

1996-01-01

390

International Nuclear Information System (INIS)

The effect of small addition of Al on the electrochemical performances was investigated by open circuit potential and Tafel Extrapolation method. The results show that open circuit potential reveals as-cast Mg containing Ca alloys with minor content of Al maintained highly negative potential with the range of -1.68 to -1.63 VSCE in comparison to both pure Mg (-1.60VSCE) and commercial high potential Mg content. Corrosion rate for the as-cast samples remains higher (30-17 mpy) than pure Mg (3 mpy) and commercial high potential Mg anode (14 mpy). The increasing small content of Al results in the reduction of corrosion rate significantly. Therefore, it proves that the performance of Mg containing Ca alloy is strongly influenced by the concentration of Al. (author)

2009-01-01

391

Dissolution of chromium in sulfuric acid

Directory of Open Access Journals (Sweden)

Full Text Available By combining electrochemical corrosion rate measurements and spectrophotometric analysis of the electrolyte it was shown that at room temperature chromium dissolves in deaerated 0.1 M Na2SO4 + H2SO4 (pH 1) solution as Cr(II) and Cr(III) ions in he ratio Cr(II) : Cr(III) @ 7 : 1. This process was stable over 4 h without any detectable change. The total corrosion rate of chromium calculated from the analytical data is about 12 times higher, than that determined electrochemically by cathodic Tafel line extrapolation to the corrosion potential. This finding was confirmed by applying the weight-loss method for the determination of the corrosion rate. This enormous difference between these experimentally determined corrosion rates can be explained by the rather fast, ?anomalous? dissolution process proposed by Kolotyrkin and coworkers (chemical reaction of Cr with H2O molecules) occurring simultaneously with the electrochemical corrosion process.

D. M. DRAZIC; J. P. POPIC

2002-01-01

392

Energy Technology Data Exchange (ETDEWEB)

The use of electrochemical techniques in assessing the porosity of electroless nickel deposits (1--24 {micro}m) on steel substrates from hypophosphite baths is considered. The corrosion rate of the coated samples immersed in 0.125M H{sub 2}SO{sub 4} at 22 C was determined using Tafel extrapolation and was found to decrease with decreasing porosity. Analysis of anodic polarization curves and current-time data at fixed potentials gave a good indication of the extent of deposit porosity. The use of galvanic coupling experiments between a non-porous coating and test samples of varying deposit thickness was also examined. The shape of the porosity vs. coating thickness curve was similar for all the methods investigated, the porosity decreasing for thicker deposits.

Kerr, C.; Barker, D.; Walsh, F. [Univ. of Portsmouth (United Kingdom). School of Chemistry, Physics and Radiography

1997-12-01

393

UK PubMed Central (United Kingdom)

BACKGROUND: Post-launch drug safety monitoring is essential for the detection of adverse drug signals that may be missed during preclinical trials. Traditional methods of postmarketing surveillance such as spontaneous reporting have intrinsic limitations, many of which can be overcome by the additional application of structured pharmacoepidemiological approaches. However, further improvement in drug safety monitoring requires a shift towards more proactive pharmacoepidemiological methods that can detect adverse drug signals as they occur in the population. OBJECTIVE: To assess the feasibility of using proactive monitoring of an electronic medical record system, in combination with an independent endpoint adjudication committee, to detect adverse events among users of selected drugs. METHODS: UK General Practice Research Database (GPRD) information was used to detect acute liver disorder associated with the use of amoxicillin/clavulanic acid (hepatotoxic) or low-dose aspirin (acetylsalicylic acid [non-hepatotoxic]). Individuals newly prescribed these drugs between 1 October 2005 and 31 March 2006 were identified. Acute liver disorder cases were assessed using GPRD computer records in combination with case validation by an independent endpoint adjudication committee. Signal generation thresholds were based on the background rate of acute liver disorder in the general population. RESULTS: Over a 6-month period, 8148 patients newly prescribed amoxicillin/clavulanic acid and 5577 patients newly prescribed low-dose aspirin were identified. Within this cohort, searches identified 11 potential liver disorder cases from computerized records: six for amoxicillin/clavulanic acid and five for low-dose aspirin. The independent endpoint adjudication committee refined this to four potential acute liver disorder cases for whom paper-based information was requested for final case assessment. Final case assessments confirmed no cases of acute liver disorder. The time taken for this study was 18 months (6 months for recruitment and 12 months for data management and case validation). To reach the estimated target exposure necessary to raise or rule out a signal of concern to public health, we determined that a recruitment period 2-3 times longer than that used in this study would be required. Based on the real market uptake of six commonly used medicinal products launched between 2001 and 2006 in the UK (budesonide/eformoterol [fixed-dose combination], duloxetine, ezetimibe, metformin/rosiglitazone [fixed-dose combination], tiotropium bromide and tadalafil) the target exposure would not have been reached until the fifth year of marketing using a single database. CONCLUSION: It is feasible to set up a system that actively monitors drug safety using a healthcare database and an independent endpoint adjudication committee. However, future successful implementation will require multiple databases to be queried so that larger study populations are included. This requires further development and harmonization of international healthcare databases.

Johansson S; Wallander MA; de Abajo FJ; García Rodríguez LA

2010-03-01

394

Modified method for obtaining the critical cooling rate for vitrification of polymers

Scientific Electronic Library Online (English)

Full Text Available Abstract in english Due to the relevance of the critical cooling rate, Rc, for glasses, Barandiarán and Colmenero (BC) developed a method for calculating Rc as a function of the crystallization temperature on cooling obtained from thermal analysis. The critical cooling rate is obtained by the extrapolation method to conditions of infinity undercooling. However, for polymers, there is a strong reason for modifying the original BC method. In this case, the extrapolation must be extended only (more) to the undercooling associated to the glass transition temperature, Tg, because no crystallization can occur below this temperature. Following this modified method (MBC) proposed by the present authors, the critical cooling rate for PP, PEEK, P10MS and PET were determined. The results showed that the new values are much lower than those obtained by the original BC method.

Canova, Claudia; Carvalho, Benjamim de Melo

2007-12-01

395

International Nuclear Information System (INIS)

[en] 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.)[de] Das praxisbezogene motortechnische Problem, Rueckschluesse von dem nur ueber kurze Zeiten kontinuierlich gemessenen Verschleissverhalten einiger kritischer Dieselmotorbauteile auf das sich nach langen Motorlaufzeiten einstellende Verschleissverhalten derselben Bauteile ziehen zu koennen, wird mit mathematisch statistischen Methoden behandelt. Es wurde ein System entwickelt, das auf der Basis in der Literatur bekannter statistischer Verfahren aus den Ergebnissen eines Einzelversuchs die Hoehe der oberen Grenze der Verschleissrate fuer berechnete Prozentsaetze der gleichen Bauteile bestimmt, wie sie im Einzelversuch benutzt werden. Des weiteren wird der Zusammenhang zwischen Kolbenringflanken-Verschleissbeschleunigung und Kolbenringbruch eroertert und ein Verfahren zur Lebensdauerabschaetzung bezueglich des Bruches von Kolbenringen in Dieselmotoren angegeben. Die Eignung der beschriebenen Verfahren fuer die Motorenentwicklung wird anhand praktischer Beipiele nachgewiesen. (orig.)

1979-01-01

396

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Introducción: la excursión sistólica del plano lateral del anillo tricuspídeo (TAPSE) es un parámetro útil en la evaluación de la función del ventrículo derecho en pacientes pediátricos. Objetivos: mostrar los valores normales del TAPSE en niños cubanos según grupos etarios, y describir su relación con la edad, gasto del ventrículo izquierdo, tiempo de aceleración pulmonar y la fracción de eyección del ventrículo izquierdo. Métodos: se realizó un estud (more) io prospectivo en el que se incluyeron 102 niños normales, a cuya medición del TAPSE se les realizó adaptando el programa para la mensuración de la distancia entre el punto E y el septum interventricular. Resultados: el TAPSE medio fue de 19,4 mm (DS±6) con valores medios en la primera semana de 9,5 mm hasta 21,2 a los 5 años y 24,1 en niños mayores. Se encontró correlación positiva significativa entre el TAPSE y la edad (r= 0,679) descrita por la ecuación TAPSE= 13,2787 + 5,2354 log (X). Se mostraron los valores del TAPSE en 5 grupos de edades. Se encontró también una correlación significativa entre el TAPSE, el tiempo de aceleración pulmonar y el gasto sistólico del ventrículo izquierdo. Conclusiones: existen 5 grupos etarios bien definidos, los mayores cambios del TAPSE se presentan antes de los 5 años de edad, y se encontró una relación logarítmica entre el TAPSE, la edad y el tiempo de aceleración pulmonar. Se recomienda el programa utilizado como alternativa en la medición del TAPSE. Abstract in english Introduction: the tricuspid annular plane systolic excursion (TAPSE) is a useful parameter to evaluate the right ventricular function in pediatric patients. Objectives: to show the normal values of TAPSE in Cuban children by age groups, and to describe their relationship with the age, the left ventricular output, the pulmonary acceleration time and the ejection fraction of the left ventricle. Methods: a prospective study included 102 normal children to whom TAPSE was meas (more) ured by adapting the program for distance mensuration between point E and the interventricular septum. Results: average TAPSE was 19.4 mm (DS±6) with mean values equal to 9.5 mm in the first week up to 21.2 mm at 5 years and 24.1 in older children. There was significant positive correlation between TAPSE figures and age (r= 0.679) described in equation TAPSE= 13.2787 + 5.2354 log (X). The TAPSE values were presented in five age groups. It was also found that there was significant correlation among TAPSE, pulmonary acceleration time and systolic output of the left ventricle. Conclusions: there exist five well-defined age groups, the major changes occur before 5 years of age and log relation was found among TAPSE, age and pulmonary acceleration time. The used program is recommended as an alternative to measure TAPSE.

Ozores Suárez, Francisco Javier

2013-09-01

397

International Nuclear Information System (INIS)

A simple method has been developed for determining the immunoreactivity of radiolabelled monoclonal antibodies to the TAG-72 antigen. The method involves binding of a constant small amount of the antibody to increasing concentrations of bovine submaxillary mucin. The immunoreactive fraction (IRF) is then determined by linear extrapolation of binding to infinite antigen excess. Using this assay, the IRF of radioiodinated anti-TAG-72 antibodies ranged from 0.22-0.48. (author).

1993-01-01

398

Express-method for evaluating residual life of structural members under creep

International Nuclear Information System (INIS)

An approximate method is suggested to estimate residual material life for members in creep. The method is based on comparison of extrapolated curves of the long-term material strength in the initial state and after operating time. An example is given to illustrate the determination of residual life for steel 13CrMo44 of the steam lines after 125 ths h of service

1983-01-01

399

The extrapolation of animal data to humans

Energy Technology Data Exchange (ETDEWEB)

With few exceptions, human epidemiological surveys do not provide statistically significant data on the dose-response relationship for radiation-induced cancers at doses and dose rates of relevance in radiological protection. An alternative source of information is provided by the extensive body of published data on radiogenic tumours in experimental animals. Such studies provide a basis for the mechanisms involved, but great care is needed in using the dose-response relationships from studies on site specific tumours to predict relationships for similar site specific cancers in man. (author).

Smith, H. (ICRP, Didcot (United Kingdom))

1992-01-01

400

Comment on "Flavor extrapolations and staggered fermions"

In a recent paper [hep-lat/0603020], Creutz claims that the rooting trick used in simulations of staggered fermions to reduce the number of tastes fails whenever the desired theory has an odd number of continuum flavors. Here we refute his argument.

Bernard, C; Shamir, Y; Sharpe, S; Bernard, Claude; Golterman, Maarten; Shamir, Yigal; Sharpe, Stephen

2006-01-01

401

International Nuclear Information System (INIS)

Comparative measurements of the beta-particle depth dose distribution for a planar 147Pm source were determined using an extrapolation chamber (ECH), radiochromic dye films (RDF) and 7LiF ultra thin thermoluminescence dosemeters (utTLD). The absolute dose estimates provided by the ECH are in excellent agreement with respect to those obtained from RDF dosemeters. In general the agreement between the ECH and the RDF were within 10%. The depth doses initially obtained using 7LiF utTLD dosemeters assuming the dosemeter centre as the effective point of measurement exhibited an overestimation from 18% for the first 10 mg.cm-2 up to 60% at 30 mg.cm-2 with respect to the ECH measurements. However in this assumption the utTLD estimations neglected the dose gradient inside the dosemeter. In order to take this into account the observed relation between the dose rate measured for each utTLD disc and its corresponding mass thickness was used to calculate the dose rate at the disc surface. A significant improvement in terms of agreement with the absolute measurements was achieved using this approach. The much higher sensitivity of utTLDs compared with ECH and RDF make this technique particularly useful for absorbed dose measurements for low activity beta particle sources. (author)

1999-01-01

402

Energy Technology Data Exchange (ETDEWEB)

Comparative measurements of the beta-particle depth dose distribution for a planar {sup 147}Pm source were determined using an extrapolation chamber (ECH), radiochromic dye films (RDF) and {sup 7}LiF ultra thin thermoluminescence dosemeters (utTLD). The absolute dose estimates provided by the ECH are in excellent agreement with respect to those obtained from RDF dosemeters. In general the agreement between the ECH and the RDF were within 10%. The depth doses initially obtained using {sup 7}LiF utTLD dosemeters assuming the dosemeter centre as the effective point of measurement exhibited an overestimation from 18% for the first 10 mg.cm{sup -2} up to 60% at 30 mg.cm{sup -2} with respect to the ECH measurements. However in this assumption the utTLD estima