Dynamical basis set

International Nuclear Information System (INIS)

Blanco, M.; Heller, E.J.

1985-01-01

A new Cartesian basis set is defined that is suitable for the representation of molecular vibration-rotation bound states. The Cartesian basis functions are superpositions of semiclassical states generated through the use of classical trajectories that conform to the intrinsic dynamics of the molecule. Although semiclassical input is employed, the method becomes ab initio through the standard matrix diagonalization variational method. Special attention is given to classical-quantum correspondences for angular momentum. In particular, it is shown that the use of semiclassical information preferentially leads to angular momentum eigenstates with magnetic quantum number Vertical BarMVertical Bar equal to the total angular momentum J. The present method offers a reliable technique for representing highly excited vibrational-rotational states where perturbation techniques are no longer applicable

The ω-limit sets of a flow and periodic orbits

International Nuclear Information System (INIS)

Wang Xiaoxia; Blackmore, Denis; Wang Chengwen

2009-01-01

In this paper we discuss the ω-limit sets of a flow using the Conley theory, chain recurrence and Morse decompositions. Our results generalize and improve the related result in [Schropp J. A reduction principle for ω-limit sets. Z Angew Math Meth 1996;76(6):349-56], and we also show how they can be used as a basis for some new criteria for the existence of periodic orbits.

Density Functional Theory and the Basis Set Truncation Problem with Correlation Consistent Basis Sets: Elephant in the Room or Mouse in the Closet?

Science.gov (United States)

Feller, David; Dixon, David A

2018-03-08

Two recent papers in this journal called into question the suitability of the correlation consistent basis sets for density functional theory (DFT) calculations, because the sets were designed for correlated methods such as configuration interaction, perturbation theory, and coupled cluster theory. These papers focused on the ability of the correlation consistent and other basis sets to reproduce total energies, atomization energies, and dipole moments obtained from "quasi-exact" multiwavelet results. Undesirably large errors were observed for the correlation consistent basis sets. One of the papers argued that basis sets specifically optimized for DFT methods were "essential" for obtaining high accuracy. In this work we re-examined the performance of the correlation consistent basis sets by resolving problems with the previous calculations and by making more appropriate basis set choices for the alkali and alkaline-earth metals and second-row elements. When this is done, the statistical errors with respect to the benchmark values and with respect to DFT optimized basis sets are greatly reduced, especially in light of the relatively large intrinsic error of the underlying DFT method. When judged with respect to high-quality Feller-Peterson-Dixon coupled cluster theory atomization energies, the PBE0 DFT method used in the previous studies exhibits a mean absolute deviation more than a factor of 50 larger than the quintuple zeta basis set truncation error.

Basis set convergence on static electric dipole polarizability calculations of alkali-metal clusters

International Nuclear Information System (INIS)

Souza, Fabio A. L. de; Jorge, Francisco E.

2013-01-01

A hierarchical sequence of all-electron segmented contracted basis sets of double, triple and quadruple zeta valence qualities plus polarization functions augmented with diffuse functions for the atoms from H to Ar was constructed. A systematic study of basis sets required to obtain reliable and accurate values of static dipole polarizabilities of lithium and sodium clusters (n = 2, 4, 6 and 8) at their optimized equilibrium geometries is reported. Three methods are examined: Hartree-Fock (HF), second-order Moeller-Plesset perturbation theory (MP2), and density functional theory (DFT). By direct calculations or by fitting the directly calculated values through one extrapolation scheme, estimates of the HF, MP2 and DFT complete basis set limits were obtained. Comparison with experimental and theoretical data reported previously in the literature is done (author)

Basis set convergence on static electric dipole polarizability calculations of alkali-metal clusters

Energy Technology Data Exchange (ETDEWEB)

Souza, Fabio A. L. de; Jorge, Francisco E., E-mail: jorge@cce.ufes.br [Departamento de Fisica, Universidade Federal do Espirito Santo, 29060-900 Vitoria-ES (Brazil)

2013-07-15

A hierarchical sequence of all-electron segmented contracted basis sets of double, triple and quadruple zeta valence qualities plus polarization functions augmented with diffuse functions for the atoms from H to Ar was constructed. A systematic study of basis sets required to obtain reliable and accurate values of static dipole polarizabilities of lithium and sodium clusters (n = 2, 4, 6 and 8) at their optimized equilibrium geometries is reported. Three methods are examined: Hartree-Fock (HF), second-order Moeller-Plesset perturbation theory (MP2), and density functional theory (DFT). By direct calculations or by fitting the directly calculated values through one extrapolation scheme, estimates of the HF, MP2 and DFT complete basis set limits were obtained. Comparison with experimental and theoretical data reported previously in the literature is done (author)

Development of new auxiliary basis functions of the Karlsruhe segmented contracted basis sets including diffuse basis functions (def2-SVPD, def2-TZVPPD, and def2-QVPPD) for RI-MP2 and RI-CC calculations.

Science.gov (United States)

Hellweg, Arnim; Rappoport, Dmitrij

2015-01-14

We report optimized auxiliary basis sets for use with the Karlsruhe segmented contracted basis sets including moderately diffuse basis functions (Rappoport and Furche, J. Chem. Phys., 2010, 133, 134105) in resolution-of-the-identity (RI) post-self-consistent field (post-SCF) computations for the elements H-Rn (except lanthanides). The errors of the RI approximation using optimized auxiliary basis sets are analyzed on a comprehensive test set of molecules containing the most common oxidation states of each element and do not exceed those of the corresponding unaugmented basis sets. During these studies an unsatisfying performance of the def2-SVP and def2-QZVPP auxiliary basis sets for Barium was found and improved sets are provided. We establish the versatility of the def2-SVPD, def2-TZVPPD, and def2-QZVPPD basis sets for RI-MP2 and RI-CC (coupled-cluster) energy and property calculations. The influence of diffuse basis functions on correlation energy, basis set superposition error, atomic electron affinity, dipole moments, and computational timings is evaluated at different levels of theory using benchmark sets and showcase examples.

The Dirac Equation in the algebraic approximation. VII. A comparison of molecular finite difference and finite basis set calculations using distributed Gaussian basis sets

NARCIS (Netherlands)

Quiney, H. M.; Glushkov, V. N.; Wilson, S.; Sabin,; Brandas, E

2001-01-01

A comparison is made of the accuracy achieved in finite difference and finite basis set approximations to the Dirac equation for the ground state of the hydrogen molecular ion. The finite basis set calculations are carried out using a distributed basis set of Gaussian functions the exponents and

Novel gene sets improve set-level classification of prokaryotic gene expression data.

Science.gov (United States)

Holec, Matěj; Kuželka, Ondřej; Železný, Filip

2015-10-28

Set-level classification of gene expression data has received significant attention recently. In this setting, high-dimensional vectors of features corresponding to genes are converted into lower-dimensional vectors of features corresponding to biologically interpretable gene sets. The dimensionality reduction brings the promise of a decreased risk of overfitting, potentially resulting in improved accuracy of the learned classifiers. However, recent empirical research has not confirmed this expectation. Here we hypothesize that the reported unfavorable classification results in the set-level framework were due to the adoption of unsuitable gene sets defined typically on the basis of the Gene ontology and the KEGG database of metabolic networks. We explore an alternative approach to defining gene sets, based on regulatory interactions, which we expect to collect genes with more correlated expression. We hypothesize that such more correlated gene sets will enable to learn more accurate classifiers. We define two families of gene sets using information on regulatory interactions, and evaluate them on phenotype-classification tasks using public prokaryotic gene expression data sets. From each of the two gene-set families, we first select the best-performing subtype. The two selected subtypes are then evaluated on independent (testing) data sets against state-of-the-art gene sets and against the conventional gene-level approach. The novel gene sets are indeed more correlated than the conventional ones, and lead to significantly more accurate classifiers. The novel gene sets are indeed more correlated than the conventional ones, and lead to significantly more accurate classifiers. Novel gene sets defined on the basis of regulatory interactions improve set-level classification of gene expression data. The experimental scripts and other material needed to reproduce the experiments are available at http://ida.felk.cvut.cz/novelgenesets.tar.gz.

An expanded calibration study of the explicitly correlated CCSD(T)-F12b method using large basis set standard CCSD(T) atomization energies.

Science.gov (United States)

Feller, David; Peterson, Kirk A

2013-08-28

The effectiveness of the recently developed, explicitly correlated coupled cluster method CCSD(T)-F12b is examined in terms of its ability to reproduce atomization energies derived from complete basis set extrapolations of standard CCSD(T). Most of the standard method findings were obtained with aug-cc-pV7Z or aug-cc-pV8Z basis sets. For a few homonuclear diatomic molecules it was possible to push the basis set to the aug-cc-pV9Z level. F12b calculations were performed with the cc-pVnZ-F12 (n = D, T, Q) basis set sequence and were also extrapolated to the basis set limit using a Schwenke-style, parameterized formula. A systematic bias was observed in the F12b method with the (VTZ-F12/VQZ-F12) basis set combination. This bias resulted in the underestimation of reference values associated with small molecules (valence correlation energies 0.5 E(h)) and an even larger overestimation of atomization energies for bigger systems. Consequently, caution should be exercised in the use of F12b for high accuracy studies. Root mean square and mean absolute deviation error metrics for this basis set combination were comparable to complete basis set values obtained with standard CCSD(T) and the aug-cc-pVDZ through aug-cc-pVQZ basis set sequence. However, the mean signed deviation was an order of magnitude larger. Problems partially due to basis set superposition error were identified with second row compounds which resulted in a weak performance for the smaller VDZ-F12/VTZ-F12 combination of basis sets.

On the use of Locally Dense Basis Sets in the Calculation of EPR Hyperfine Couplings

DEFF Research Database (Denmark)

Hedegård, Erik D.; Sauer, Stephan P. A.; Milhøj, Birgitte O.

2013-01-01

The usage of locally dense basis sets in the calculation of Electron Paramagnetic Resonance (EPR) hyperne coupling constants is investigated at the level of Density Functional Theory (DFT) for two model systems of biologically important transition metal complexes: One for the active site in the c......The usage of locally dense basis sets in the calculation of Electron Paramagnetic Resonance (EPR) hyperne coupling constants is investigated at the level of Density Functional Theory (DFT) for two model systems of biologically important transition metal complexes: One for the active site...

On the use of locally dense basis sets in the calculation of EPR hyperfine couplings

DEFF Research Database (Denmark)

Milhøj, Birgitte Olai; Hedegård, Erik D.; Sauer, Stephan P. A.

2013-01-01

The usage of locally dense basis sets in the calculation of Electron Paramagnetic Resonance (EPR) hyperne coupling constants is investigated at the level of Density Functional Theory (DFT) for two model systems of biologically important transition metal complexes: One for the active site in the c......The usage of locally dense basis sets in the calculation of Electron Paramagnetic Resonance (EPR) hyperne coupling constants is investigated at the level of Density Functional Theory (DFT) for two model systems of biologically important transition metal complexes: One for the active site...

Quantum Dynamics with Short-Time Trajectories and Minimal Adaptive Basis Sets.

Science.gov (United States)

Saller, Maximilian A C; Habershon, Scott

2017-07-11

Methods for solving the time-dependent Schrödinger equation via basis set expansion of the wave function can generally be categorized as having either static (time-independent) or dynamic (time-dependent) basis functions. We have recently introduced an alternative simulation approach which represents a middle road between these two extremes, employing dynamic (classical-like) trajectories to create a static basis set of Gaussian wavepackets in regions of phase-space relevant to future propagation of the wave function [J. Chem. Theory Comput., 11, 8 (2015)]. Here, we propose and test a modification of our methodology which aims to reduce the size of basis sets generated in our original scheme. In particular, we employ short-time classical trajectories to continuously generate new basis functions for short-time quantum propagation of the wave function; to avoid the continued growth of the basis set describing the time-dependent wave function, we employ Matching Pursuit to periodically minimize the number of basis functions required to accurately describe the wave function. Overall, this approach generates a basis set which is adapted to evolution of the wave function while also being as small as possible. In applications to challenging benchmark problems, namely a 4-dimensional model of photoexcited pyrazine and three different double-well tunnelling problems, we find that our new scheme enables accurate wave function propagation with basis sets which are around an order-of-magnitude smaller than our original trajectory-guided basis set methodology, highlighting the benefits of adaptive strategies for wave function propagation.

Evolution in time of an N-atom system. I. A physical basis set for the projection of the master equation

International Nuclear Information System (INIS)

Freedhoff, Helen

2004-01-01

We study an aggregate of N identical two-level atoms (TLA's) coupled by the retarded interatomic interaction, using the Lehmberg-Agarwal master equation. First, we calculate the entangled eigenstates of the system; then, we use these eigenstates as a basis set for the projection of the master equation. We demonstrate that in this basis the equations of motion for the level populations, as well as the expressions for the emission and absorption spectra, assume a simple mathematical structure and allow for a transparent physical interpretation. To illustrate the use of the general theory in emission processes, we study an isosceles triangle of atoms, and present in the long wavelength limit the (cascade) emission spectrum for a hexagon of atoms fully excited at t=0. To illustrate its use for absorption processes, we tabulate (in the same limit) the biexciton absorption frequencies, linewidths, and relative intensities for polygons consisting of N=2,...,9 TLA's

The aug-cc-pVnZ-F12 basis set family: Correlation consistent basis sets for explicitly correlated benchmark calculations on anions and noncovalent complexes.

Science.gov (United States)

Sylvetsky, Nitai; Kesharwani, Manoj K; Martin, Jan M L

2017-10-07

We have developed a new basis set family, denoted as aug-cc-pVnZ-F12 (or aVnZ-F12 for short), for explicitly correlated calculations. The sets included in this family were constructed by supplementing the corresponding cc-pVnZ-F12 sets with additional diffuse functions on the higher angular momenta (i.e., additional d-h functions on non-hydrogen atoms and p-g on hydrogen atoms), optimized for the MP2-F12 energy of the relevant atomic anions. The new basis sets have been benchmarked against electron affinities of the first- and second-row atoms, the W4-17 dataset of total atomization energies, the S66 dataset of noncovalent interactions, the Benchmark Energy and Geometry Data Base water cluster subset, and the WATER23 subset of the GMTKN24 and GMTKN30 benchmark suites. The aVnZ-F12 basis sets displayed excellent performance, not just for electron affinities but also for noncovalent interaction energies of neutral and anionic species. Appropriate CABSs (complementary auxiliary basis sets) were explored for the S66 noncovalent interaction benchmark: between similar-sized basis sets, CABSs were found to be more transferable than generally assumed.

Gaussian basis sets for use in correlated molecular calculations. XI. Pseudopotential-based and all-electron relativistic basis sets for alkali metal (K-Fr) and alkaline earth (Ca-Ra) elements

Science.gov (United States)

Hill, J. Grant; Peterson, Kirk A.

2017-12-01

New correlation consistent basis sets based on pseudopotential (PP) Hamiltonians have been developed from double- to quintuple-zeta quality for the late alkali (K-Fr) and alkaline earth (Ca-Ra) metals. These are accompanied by new all-electron basis sets of double- to quadruple-zeta quality that have been contracted for use with both Douglas-Kroll-Hess (DKH) and eXact 2-Component (X2C) scalar relativistic Hamiltonians. Sets for valence correlation (ms), cc-pVnZ-PP and cc-pVnZ-(DK,DK3/X2C), in addition to outer-core correlation [valence + (m-1)sp], cc-p(w)CVnZ-PP and cc-pwCVnZ-(DK,DK3/X2C), are reported. The -PP sets have been developed for use with small-core PPs [I. S. Lim et al., J. Chem. Phys. 122, 104103 (2005) and I. S. Lim et al., J. Chem. Phys. 124, 034107 (2006)], while the all-electron sets utilized second-order DKH Hamiltonians for 4s and 5s elements and third-order DKH for 6s and 7s. The accuracy of the basis sets is assessed through benchmark calculations at the coupled-cluster level of theory for both atomic and molecular properties. Not surprisingly, it is found that outer-core correlation is vital for accurate calculation of the thermodynamic and spectroscopic properties of diatomic molecules containing these elements.

Gaussian basis sets for use in correlated molecular calculations. XI. Pseudopotential-based and all-electron relativistic basis sets for alkali metal (K-Fr) and alkaline earth (Ca-Ra) elements.

Science.gov (United States)

Hill, J Grant; Peterson, Kirk A

2017-12-28

New correlation consistent basis sets based on pseudopotential (PP) Hamiltonians have been developed from double- to quintuple-zeta quality for the late alkali (K-Fr) and alkaline earth (Ca-Ra) metals. These are accompanied by new all-electron basis sets of double- to quadruple-zeta quality that have been contracted for use with both Douglas-Kroll-Hess (DKH) and eXact 2-Component (X2C) scalar relativistic Hamiltonians. Sets for valence correlation (ms), cc-pVnZ-PP and cc-pVnZ-(DK,DK3/X2C), in addition to outer-core correlation [valence + (m-1)sp], cc-p(w)CVnZ-PP and cc-pwCVnZ-(DK,DK3/X2C), are reported. The -PP sets have been developed for use with small-core PPs [I. S. Lim et al., J. Chem. Phys. 122, 104103 (2005) and I. S. Lim et al., J. Chem. Phys. 124, 034107 (2006)], while the all-electron sets utilized second-order DKH Hamiltonians for 4s and 5s elements and third-order DKH for 6s and 7s. The accuracy of the basis sets is assessed through benchmark calculations at the coupled-cluster level of theory for both atomic and molecular properties. Not surprisingly, it is found that outer-core correlation is vital for accurate calculation of the thermodynamic and spectroscopic properties of diatomic molecules containing these elements.

Systematic determination of extended atomic orbital basis sets and application to molecular SCF and MCSCF calculations

Energy Technology Data Exchange (ETDEWEB)

Feller, D.F.

1979-01-01

The behavior of the two exponential parameters in an even-tempered gaussian basis set is investigated as the set optimally approaches an integral transform representation of the radial portion of atomic and molecular orbitals. This approach permits a highly accurate assessment of the Hartree-Fock limit for atoms and molecules.

Point Set Denoising Using Bootstrap-Based Radial Basis Function.

Science.gov (United States)

Liew, Khang Jie; Ramli, Ahmad; Abd Majid, Ahmad

2016-01-01

This paper examines the application of a bootstrap test error estimation of radial basis functions, specifically thin-plate spline fitting, in surface smoothing. The presence of noisy data is a common issue of the point set model that is generated from 3D scanning devices, and hence, point set denoising is one of the main concerns in point set modelling. Bootstrap test error estimation, which is applied when searching for the smoothing parameters of radial basis functions, is revisited. The main contribution of this paper is a smoothing algorithm that relies on a bootstrap-based radial basis function. The proposed method incorporates a k-nearest neighbour search and then projects the point set to the approximated thin-plate spline surface. Therefore, the denoising process is achieved, and the features are well preserved. A comparison of the proposed method with other smoothing methods is also carried out in this study.

Groebner basis, resultants and the generalized Mandelbrot set

Energy Technology Data Exchange (ETDEWEB)

Geum, Young Hee [Centre of Research for Computational Sciences and Informatics in Biology, Bioindustry, Environment, Agriculture and Healthcare, University of Malaya, 50603 Kuala Lumpur (Malaysia)], E-mail: conpana@empal.com; Hare, Kevin G. [Department of Pure Mathematics, University of Waterloo, Waterloo, Ont., N2L 3G1 (Canada)], E-mail: kghare@math.uwaterloo.ca

2009-10-30

This paper demonstrates how the Groebner basis algorithm can be used for finding the bifurcation points in the generalized Mandelbrot set. It also shows how resultants can be used to find components of the generalized Mandelbrot set.

Groebner basis, resultants and the generalized Mandelbrot set

International Nuclear Information System (INIS)

Geum, Young Hee; Hare, Kevin G.

2009-01-01

This paper demonstrates how the Groebner basis algorithm can be used for finding the bifurcation points in the generalized Mandelbrot set. It also shows how resultants can be used to find components of the generalized Mandelbrot set.

Localized atomic basis set in the projector augmented wave method

DEFF Research Database (Denmark)

Larsen, Ask Hjorth; Vanin, Marco; Mortensen, Jens Jørgen

2009-01-01

We present an implementation of localized atomic-orbital basis sets in the projector augmented wave (PAW) formalism within the density-functional theory. The implementation in the real-space GPAW code provides a complementary basis set to the accurate but computationally more demanding grid...

Point Set Denoising Using Bootstrap-Based Radial Basis Function.

Directory of Open Access Journals (Sweden)

Khang Jie Liew

Full Text Available This paper examines the application of a bootstrap test error estimation of radial basis functions, specifically thin-plate spline fitting, in surface smoothing. The presence of noisy data is a common issue of the point set model that is generated from 3D scanning devices, and hence, point set denoising is one of the main concerns in point set modelling. Bootstrap test error estimation, which is applied when searching for the smoothing parameters of radial basis functions, is revisited. The main contribution of this paper is a smoothing algorithm that relies on a bootstrap-based radial basis function. The proposed method incorporates a k-nearest neighbour search and then projects the point set to the approximated thin-plate spline surface. Therefore, the denoising process is achieved, and the features are well preserved. A comparison of the proposed method with other smoothing methods is also carried out in this study.

Dynamical pruning of static localized basis sets in time-dependent quantum dynamics

NARCIS (Netherlands)

McCormack, D.A.

2006-01-01

We investigate the viability of dynamical pruning of localized basis sets in time-dependent quantum wave packet methods. Basis functions that have a very small population at any given time are removed from the active set. The basis functions themselves are time independent, but the set of active

Basis Set Convergence of Indirect Spin-Spin Coupling Constants in the Kohn-Sham Limit for Several Small Molecules

Czech Academy of Sciences Publication Activity Database

Kupka, T.; Nieradka, M.; Stachów, M.; Pluta, T.; Nowak, P.; Kjaer, H.; Kongsted, J.; Kaminský, Jakub

2012-01-01

Roč. 116, č. 14 (2012), s. 3728-3738 ISSN 1089-5639 R&D Projects: GA ČR GPP208/10/P356 Institutional research plan: CEZ:AV0Z40550506 Keywords : consistent basis-sets * density-functional methods * ab-inition calculations * polarization propagator approximation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.771, year: 2012

Level-set reconstruction algorithm for ultrafast limited-angle X-ray computed tomography of two-phase flows.

Science.gov (United States)

Bieberle, M; Hampel, U

2015-06-13

Tomographic image reconstruction is based on recovering an object distribution from its projections, which have been acquired from all angular views around the object. If the angular range is limited to less than 180° of parallel projections, typical reconstruction artefacts arise when using standard algorithms. To compensate for this, specialized algorithms using a priori information about the object need to be applied. The application behind this work is ultrafast limited-angle X-ray computed tomography of two-phase flows. Here, only a binary distribution of the two phases needs to be reconstructed, which reduces the complexity of the inverse problem. To solve it, a new reconstruction algorithm (LSR) based on the level-set method is proposed. It includes one force function term accounting for matching the projection data and one incorporating a curvature-dependent smoothing of the phase boundary. The algorithm has been validated using simulated as well as measured projections of known structures, and its performance has been compared to the algebraic reconstruction technique and a binary derivative of it. The validation as well as the application of the level-set reconstruction on a dynamic two-phase flow demonstrated its applicability and its advantages over other reconstruction algorithms. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Accurate Ionization Potentials and Electron Affinities of Acceptor Molecules I. Reference Data at the CCSD(T) Complete Basis Set Limit

KAUST Repository

Richard, Ryan M.

2016-01-05

© 2016 American Chemical Society. In designing organic materials for electronics applications, particularly for organic photovoltaics (OPV), the ionization potential (IP) of the donor and the electron affinity (EA) of the acceptor play key roles. This makes OPV design an appealing application for computational chemistry since IPs and EAs are readily calculable from most electronic structure methods. Unfortunately reliable, high-accuracy wave function methods, such as coupled cluster theory with single, double, and perturbative triples [CCSD(T)] in the complete basis set (CBS) limit are too expensive for routine applications to this problem for any but the smallest of systems. One solution is to calibrate approximate, less computationally expensive methods against a database of high-accuracy IP/EA values; however, to our knowledge, no such database exists for systems related to OPV design. The present work is the first of a multipart study whose overarching goal is to determine which computational methods can be used to reliably compute IPs and EAs of electron acceptors. This part introduces a database of 24 known organic electron acceptors and provides high-accuracy vertical IP and EA values expected to be within ±0.03 eV of the true non-relativistic, vertical CCSD(T)/CBS limit. Convergence of IP and EA values toward the CBS limit is studied systematically for the Hartree-Fock, MP2 correlation, and beyond-MP2 coupled cluster contributions to the focal point estimates.

On the performance of atomic natural orbital basis sets: A full configuration interaction study

International Nuclear Information System (INIS)

Illas, F.; Ricart, J.M.; Rubio, J.; Bagus, P.S.

1990-01-01

The performance of atomic natural orbital (ANO) basis sets has been studied by comparing self-consistant field (SCF) and full configuration interaction (CI) results obtained for the first row atoms and hydrides. The ANO results have been compared with those obtained using a segmented basis set containing the same number of contracted basis functions. The total energies obtained with the ANO basis sets are always lower than the one obtained by using the segmented one. However, for the hydrides, differential electronic correlation energy obtained with the ANO basis set may be smaller than the one recovered with the segmented set. We relate this poorer differential correlation energy for the ANO basis set to the fact that only one contracted d function is used for the ANO and segmented basis sets

Molecular basis sets - a general similarity-based approach for representing chemical spaces.

Science.gov (United States)

Raghavendra, Akshay S; Maggiora, Gerald M

2007-01-01

A new method, based on generalized Fourier analysis, is described that utilizes the concept of "molecular basis sets" to represent chemical space within an abstract vector space. The basis vectors in this space are abstract molecular vectors. Inner products among the basis vectors are determined using an ansatz that associates molecular similarities between pairs of molecules with their corresponding inner products. Moreover, the fact that similarities between pairs of molecules are, in essentially all cases, nonzero implies that the abstract molecular basis vectors are nonorthogonal, but since the similarity of a molecule with itself is unity, the molecular vectors are normalized to unity. A symmetric orthogonalization procedure, which optimally preserves the character of the original set of molecular basis vectors, is used to construct appropriate orthonormal basis sets. Molecules can then be represented, in general, by sets of orthonormal "molecule-like" basis vectors within a proper Euclidean vector space. However, the dimension of the space can become quite large. Thus, the work presented here assesses the effect of basis set size on a number of properties including the average squared error and average norm of molecular vectors represented in the space-the results clearly show the expected reduction in average squared error and increase in average norm as the basis set size is increased. Several distance-based statistics are also considered. These include the distribution of distances and their differences with respect to basis sets of differing size and several comparative distance measures such as Spearman rank correlation and Kruscal stress. All of the measures show that, even though the dimension can be high, the chemical spaces they represent, nonetheless, behave in a well-controlled and reasonable manner. Other abstract vector spaces analogous to that described here can also be constructed providing that the appropriate inner products can be directly

Simple and efficient LCAO basis sets for the diffuse states in carbon nanostructures.

Science.gov (United States)

Papior, Nick R; Calogero, Gaetano; Brandbyge, Mads

2018-06-27

We present a simple way to describe the lowest unoccupied diffuse states in carbon nanostructures in density functional theory calculations using a minimal LCAO (linear combination of atomic orbitals) basis set. By comparing plane wave basis calculations, we show how these states can be captured by adding long-range orbitals to the standard LCAO basis sets for the extreme cases of planar sp 2 (graphene) and curved carbon (C 60 ). In particular, using Bessel functions with a long range as additional basis functions retain a minimal basis size. This provides a smaller and simpler atom-centered basis set compared to the standard pseudo-atomic orbitals (PAOs) with multiple polarization orbitals or by adding non-atom-centered states to the basis.

Dynamical basis sets for algebraic variational calculations in quantum-mechanical scattering theory

Science.gov (United States)

Sun, Yan; Kouri, Donald J.; Truhlar, Donald G.; Schwenke, David W.

1990-01-01

New basis sets are proposed for linear algebraic variational calculations of transition amplitudes in quantum-mechanical scattering problems. These basis sets are hybrids of those that yield the Kohn variational principle (KVP) and those that yield the generalized Newton variational principle (GNVP) when substituted in Schlessinger's stationary expression for the T operator. Trial calculations show that efficiencies almost as great as that of the GNVP and much greater than the KVP can be obtained, even for basis sets with the majority of the members independent of energy.

A Comparison of the Behavior of Functional/Basis Set Combinations for Hydrogen-Bonding in the Water Dimer with Emphasis on Basis Set Superposition Error

OpenAIRE

Plumley, Joshua A.; Dannenberg, J. J.

2011-01-01

We evaluate the performance of nine functionals (B3LYP, M05, M05-2X, M06, M06-2X, B2PLYP, B2PLYPD, X3LYP, B97D and MPWB1K) in combination with 16 basis sets ranging in complexity from 6-31G(d) to aug-cc-pV5Z for the calculation of the H-bonded water dimer with the goal of defining which combinations of functionals and basis sets provide a combination of economy and accuracy for H-bonded systems. We have compared the results to the best non-DFT molecular orbital calculations and to experimenta...

Correlation consistent basis sets for actinides. II. The atoms Ac and Np-Lr.

Science.gov (United States)

Feng, Rulin; Peterson, Kirk A

2017-08-28

New correlation consistent basis sets optimized using the all-electron third-order Douglas-Kroll-Hess (DKH3) scalar relativistic Hamiltonian are reported for the actinide elements Ac and Np through Lr. These complete the series of sets reported previously for Th-U [K. A. Peterson, J. Chem. Phys. 142, 074105 (2015); M. Vasiliu et al., J. Phys. Chem. A 119, 11422 (2015)]. The new sets range in size from double- to quadruple-zeta and encompass both those optimized for valence (6s6p5f7s6d) and outer-core electron correlations (valence + 5s5p5d). The final sets have been contracted for both the DKH3 and eXact 2-component (X2C) Hamiltonians, yielding cc-pVnZ-DK3/cc-pVnZ-X2C sets for valence correlation and cc-pwCVnZ-DK3/cc-pwCVnZ-X2C sets for outer-core correlation (n = D, T, Q in each case). In order to test the effectiveness of the new basis sets, both atomic and molecular benchmark calculations have been carried out. In the first case, the first three atomic ionization potentials (IPs) of all the actinide elements Ac-Lr have been calculated using the Feller-Peterson-Dixon (FPD) composite approach, primarily with the multireference configuration interaction (MRCI) method. Excellent convergence towards the respective complete basis set (CBS) limits is achieved with the new sets, leading to good agreement with experiment, where these exist, after accurately accounting for spin-orbit effects using the 4-component Dirac-Hartree-Fock method. For a molecular test, the IP and atomization energy (AE) of PuO 2 have been calculated also using the FPD method but using a coupled cluster approach with spin-orbit coupling accounted for using the 4-component MRCI. The present calculations yield an IP 0 for PuO 2 of 159.8 kcal/mol, which is in excellent agreement with the experimental electron transfer bracketing value of 162 ± 3 kcal/mol. Likewise, the calculated 0 K AE of 305.6 kcal/mol is in very good agreement with the currently accepted experimental value of 303.1 ± 5 kcal

Level-Set Topology Optimization with Aeroelastic Constraints

Science.gov (United States)

Dunning, Peter D.; Stanford, Bret K.; Kim, H. Alicia

2015-01-01

Level-set topology optimization is used to design a wing considering skin buckling under static aeroelastic trim loading, as well as dynamic aeroelastic stability (flutter). The level-set function is defined over the entire 3D volume of a transport aircraft wing box. Therefore, the approach is not limited by any predefined structure and can explore novel configurations. The Sequential Linear Programming (SLP) level-set method is used to solve the constrained optimization problems. The proposed method is demonstrated using three problems with mass, linear buckling and flutter objective and/or constraints. A constraint aggregation method is used to handle multiple buckling constraints in the wing skins. A continuous flutter constraint formulation is used to handle difficulties arising from discontinuities in the design space caused by a switching of the critical flutter mode.

Optimization of auxiliary basis sets for the LEDO expansion and a projection technique for LEDO-DFT.

Science.gov (United States)

Götz, Andreas W; Kollmar, Christian; Hess, Bernd A

2005-09-01

We present a systematic procedure for the optimization of the expansion basis for the limited expansion of diatomic overlap density functional theory (LEDO-DFT) and report on optimized auxiliary orbitals for the Ahlrichs split valence plus polarization basis set (SVP) for the elements H, Li--F, and Na--Cl. A new method to deal with near-linear dependences in the LEDO expansion basis is introduced, which greatly reduces the computational effort of LEDO-DFT calculations. Numerical results for a test set of small molecules demonstrate the accuracy of electronic energies, structural parameters, dipole moments, and harmonic frequencies. For larger molecular systems the numerical errors introduced by the LEDO approximation can lead to an uncontrollable behavior of the self-consistent field (SCF) process. A projection technique suggested by Löwdin is presented in the framework of LEDO-DFT, which guarantees for SCF convergence. Numerical results on some critical test molecules suggest the general applicability of the auxiliary orbitals presented in combination with this projection technique. Timing results indicate that LEDO-DFT is competitive with conventional density fitting methods. (c) 2005 Wiley Periodicals, Inc.

Setting limits on supersymmetry using simplified models

CERN Document Server

Gutschow, C.

2012-01-01

Experimental limits on supersymmetry and similar theories are difficult to set because of the enormous available parameter space and difficult to generalize because of the complexity of single points. Therefore, more phenomenological, simplified models are becoming popular for setting experimental limits, as they have clearer physical implications. The use of these simplified model limits to set a real limit on a concrete theory has not, however, been demonstrated. This paper recasts simplified model limits into limits on a specific and complete supersymmetry model, minimal supergravity. Limits obtained under various physical assumptions are comparable to those produced by directed searches. A prescription is provided for calculating conservative and aggressive limits on additional theories. Using acceptance and efficiency tables along with the expected and observed numbers of events in various signal regions, LHC experimental results can be re-cast in this manner into almost any theoretical framework, includ...

Zeroth-order exchange energy as a criterion for optimized atomic basis sets in interatomic force calculations

International Nuclear Information System (INIS)

Varandas, A.J.C.

1980-01-01

A suggestion is made for using the zeroth-order exchange term, at the one-exchange level, in the perturbation development of the interaction energy as a criterion for optmizing the atomic basis sets in interatomic force calculations. The approach is illustrated for the case of two helium atoms. (orig.)

Incomplete basis-set problem. V. Application of CIBS to many-electron systems

International Nuclear Information System (INIS)

McDowell, K.; Lewis, L.

1982-01-01

Five versions of CIBS (corrections to an incomplete basis set) theory are used to compute first and second corrections to Roothaan--Hartree--Fock energies via expansion of a given basis set. Version one is an order by order perturbation approximation which neglects virtual orbitals; version two is a full CIBS expansion which neglects virtual orbitals; version three is an order by order perturbation approximation which includes virtual orbitals; version four is a full CIBS expansion which includes orthogonalization to virtual orbitals but neglects virtual orbital coupling terms; and version five is a full CIBS expansion with inclusion of coupling to virtual orbitals. Results are presented for the atomic and molecular systems He, Be, H 2 , LiH, Li 2 , and H 2 O. Version five is shown to produce a corrected Hartree--Fock energy which is essentially in agreement with a comparable SCF result using the same expanded basis set. Versions one through four yield varying degrees of agreement; however, it is evident that the effect of the virtual orbitals must be included. From the results, CIBS version five is shown to be a viable quantitative procedure which can be used to expand or to study the use of basis sets in quantum chemistry

Exploring nurses' and patients' perspectives of limit setting in a forensic mental health setting.

Science.gov (United States)

Maguire, Tessa; Daffern, Michael; Martin, Trish

2014-04-01

Limit setting is an intervention that is frequently used by mental health nurses. However, limit setting is poorly conceptualized, its purpose is unclear, and there are few evidence-based guidelines to assist nurses to set limits in a safe and effective manner. What is known is that the manner in which nurses set limits influences patients' perceptions of the interactions and their emotional and behavioural responses. In this qualitative study, 12 nurses and 12 patients participated in personal, semistructured interviews that aimed to explore limit setting and to propose principles to guide practice. The findings suggested that: (i) limit setting is important to safety in mental health hospitals; (ii) engaging patients in an empathic manner is necessary when setting limits (when nurses engage in an empathic manner, the therapeutic relationship is more likely to be preserved and the risk of aggressive responses is reduced); and (iii) an authoritative (fair, respectful, consistent, and knowledgeable), rather than authoritarian (controlling and indifferent), limit-setting style enhances positive outcomes with regards to adherence, reduced likelihood of aggression, and preservation of the therapeutic relationship. In conclusion, a limit-setting style characterized by empathic responding and an authoritative, rather than authoritarian interpersonal, style is recommended. Elucidating the components of this style is critical for effective training and best practice of mental health nurses, and to reduce aggressive responses from limit setting. © 2013 Australian College of Mental Health Nurses Inc.

Polarization functions for the modified m6-31G basis sets for atoms Ga through Kr.

Science.gov (United States)

Mitin, Alexander V

2013-09-05

The 2df polarization functions for the modified m6-31G basis sets of the third-row atoms Ga through Kr (Int J Quantum Chem, 2007, 107, 3028; Int J. Quantum Chem, 2009, 109, 1158) are proposed. The performances of the m6-31G, m6-31G(d,p), and m6-31G(2df,p) basis sets were examined in molecular calculations carried out by the density functional theory (DFT) method with B3LYP hybrid functional, Møller-Plesset perturbation theory of the second order (MP2), quadratic configuration interaction method with single and double substitutions and were compared with those for the known 6-31G basis sets as well as with the other similar 641 and 6-311G basis sets with and without polarization functions. Obtained results have shown that the performances of the m6-31G, m6-31G(d,p), and m6-31G(2df,p) basis sets are better in comparison with the performances of the known 6-31G, 6-31G(d,p) and 6-31G(2df,p) basis sets. These improvements are mainly reached due to better approximations of different electrons belonging to the different atomic shells in the modified basis sets. Applicability of the modified basis sets in thermochemical calculations is also discussed. © 2013 Wiley Periodicals, Inc.

Energy optimized Gaussian basis sets for the atoms T1 - Rn

International Nuclear Information System (INIS)

Faegri, K. Jr.

1987-01-01

Energy optimized Gaussian basis sets have been derived for the atoms Tl-Rn. Two sets are presented - a (20,16,10,6) set and a (22,17,13,8) set. The smallest sets yield atomic energies 107 to 123 mH above the numerical Hartree-Fock values, while the larger sets give energies 11 mH above the numerical results. Energy trends from the smaller sets indicate that reduced shielding by p-electrons may place a greater demand on the flexibility of d- and f-orbital description for the lighter elements of the series

Basis set effects on the energy of intramolecular O-H...halogen hydrogen bridges in ortho-halophenols and 2,4-dihalo-malonaldehyde

International Nuclear Information System (INIS)

Buemi, Giuseppe

2004-01-01

Ab initio calculations of hydrogen bridge energies (E HB ) of 2-halophenols were carried out at various levels of sophistication using a variety of basis sets in order to verify their ability in reproducing the experimentally-determined gas phase ordering, and the related experimental frequencies of the O-H vibration stretching mode. The semiempirical AM1 and PM3 approaches were adopted, too. Calculations were extended to the O-H...X bridge of a particular conformation of 2,4-dihalo-malonaldehyde. The results and their trend with respect to the electronegativity of the halogen series are highly dependant on the basis set. The less sophisticated 3-21G, CEP121G and LANL2DZ basis sets (with and without correlation energy inclusion) predict E HB decreasing on decreasing the electronegativity power whilst the opposite is generally found when more extended bases are used. However, all high level calculations confirm the nearly negligible energy differences between the examined O-H...X bridges

Conductance calculations with a wavelet basis set

DEFF Research Database (Denmark)

Thygesen, Kristian Sommer; Bollinger, Mikkel; Jacobsen, Karsten Wedel

2003-01-01

We present a method based on density functional theory (DFT) for calculating the conductance of a phase-coherent system. The metallic contacts and the central region where the electron scattering occurs, are treated on the same footing taking their full atomic and electronic structure into account....... The linear-response conductance is calculated from the Green's function which is represented in terms of a system-independent basis set containing wavelets with compact support. This allows us to rigorously separate the central region from the contacts and to test for convergence in a systematic way...

Identifying finite-time coherent sets from limited quantities of Lagrangian data

Energy Technology Data Exchange (ETDEWEB)

Williams, Matthew O. [Program in Applied and Computational Mathematics, Princeton University, New Jersey 08544 (United States); Rypina, Irina I. [Department of Physical Oceanography, Woods Hole Oceanographic Institute, Massachusetts 02543 (United States); Rowley, Clarence W. [Department of Mechanical and Aerospace Engineering, Princeton University, New Jersey 08544 (United States)

2015-08-15

A data-driven procedure for identifying the dominant transport barriers in a time-varying flow from limited quantities of Lagrangian data is presented. Our approach partitions state space into coherent pairs, which are sets of initial conditions chosen to minimize the number of trajectories that “leak” from one set to the other under the influence of a stochastic flow field during a pre-specified interval in time. In practice, this partition is computed by solving an optimization problem to obtain a pair of functions whose signs determine set membership. From prior experience with synthetic, “data rich” test problems, and conceptually related methods based on approximations of the Perron-Frobenius operator, we observe that the functions of interest typically appear to be smooth. We exploit this property by using the basis sets associated with spectral or “mesh-free” methods, and as a result, our approach has the potential to more accurately approximate these functions given a fixed amount of data. In practice, this could enable better approximations of the coherent pairs in problems with relatively limited quantities of Lagrangian data, which is usually the case with experimental geophysical data. We apply this method to three examples of increasing complexity: The first is the double gyre, the second is the Bickley Jet, and the third is data from numerically simulated drifters in the Sulu Sea.

Identifying finite-time coherent sets from limited quantities of Lagrangian data

International Nuclear Information System (INIS)

Williams, Matthew O.; Rypina, Irina I.; Rowley, Clarence W.

2015-01-01

A data-driven procedure for identifying the dominant transport barriers in a time-varying flow from limited quantities of Lagrangian data is presented. Our approach partitions state space into coherent pairs, which are sets of initial conditions chosen to minimize the number of trajectories that “leak” from one set to the other under the influence of a stochastic flow field during a pre-specified interval in time. In practice, this partition is computed by solving an optimization problem to obtain a pair of functions whose signs determine set membership. From prior experience with synthetic, “data rich” test problems, and conceptually related methods based on approximations of the Perron-Frobenius operator, we observe that the functions of interest typically appear to be smooth. We exploit this property by using the basis sets associated with spectral or “mesh-free” methods, and as a result, our approach has the potential to more accurately approximate these functions given a fixed amount of data. In practice, this could enable better approximations of the coherent pairs in problems with relatively limited quantities of Lagrangian data, which is usually the case with experimental geophysical data. We apply this method to three examples of increasing complexity: The first is the double gyre, the second is the Bickley Jet, and the third is data from numerically simulated drifters in the Sulu Sea

Identifying finite-time coherent sets from limited quantities of Lagrangian data.

Science.gov (United States)

Williams, Matthew O; Rypina, Irina I; Rowley, Clarence W

2015-08-01

A data-driven procedure for identifying the dominant transport barriers in a time-varying flow from limited quantities of Lagrangian data is presented. Our approach partitions state space into coherent pairs, which are sets of initial conditions chosen to minimize the number of trajectories that "leak" from one set to the other under the influence of a stochastic flow field during a pre-specified interval in time. In practice, this partition is computed by solving an optimization problem to obtain a pair of functions whose signs determine set membership. From prior experience with synthetic, "data rich" test problems, and conceptually related methods based on approximations of the Perron-Frobenius operator, we observe that the functions of interest typically appear to be smooth. We exploit this property by using the basis sets associated with spectral or "mesh-free" methods, and as a result, our approach has the potential to more accurately approximate these functions given a fixed amount of data. In practice, this could enable better approximations of the coherent pairs in problems with relatively limited quantities of Lagrangian data, which is usually the case with experimental geophysical data. We apply this method to three examples of increasing complexity: The first is the double gyre, the second is the Bickley Jet, and the third is data from numerically simulated drifters in the Sulu Sea.

Accurate and balanced anisotropic Gaussian type orbital basis sets for atoms in strong magnetic fields

Science.gov (United States)

Zhu, Wuming; Trickey, S. B.

2017-12-01

In high magnetic field calculations, anisotropic Gaussian type orbital (AGTO) basis functions are capable of reconciling the competing demands of the spherically symmetric Coulombic interaction and cylindrical magnetic (B field) confinement. However, the best available a priori procedure for composing highly accurate AGTO sets for atoms in a strong B field [W. Zhu et al., Phys. Rev. A 90, 022504 (2014)] yields very large basis sets. Their size is problematical for use in any calculation with unfavorable computational cost scaling. Here we provide an alternative constructive procedure. It is based upon analysis of the underlying physics of atoms in B fields that allow identification of several principles for the construction of AGTO basis sets. Aided by numerical optimization and parameter fitting, followed by fine tuning of fitting parameters, we devise formulae for generating accurate AGTO basis sets in an arbitrary B field. For the hydrogen iso-electronic sequence, a set depends on B field strength, nuclear charge, and orbital quantum numbers. For multi-electron systems, the basis set formulae also include adjustment to account for orbital occupations. Tests of the new basis sets for atoms H through C (1 ≤ Z ≤ 6) and ions Li+, Be+, and B+, in a wide B field range (0 ≤ B ≤ 2000 a.u.), show an accuracy better than a few μhartree for single-electron systems and a few hundredths to a few mHs for multi-electron atoms. The relative errors are similar for different atoms and ions in a large B field range, from a few to a couple of tens of millionths, thereby confirming rather uniform accuracy across the nuclear charge Z and B field strength values. Residual basis set errors are two to three orders of magnitude smaller than the electronic correlation energies in multi-electron atoms, a signal of the usefulness of the new AGTO basis sets in correlated wavefunction or density functional calculations for atomic and molecular systems in an external strong B field.

Accurate and balanced anisotropic Gaussian type orbital basis sets for atoms in strong magnetic fields.

Science.gov (United States)

Zhu, Wuming; Trickey, S B

2017-12-28

In high magnetic field calculations, anisotropic Gaussian type orbital (AGTO) basis functions are capable of reconciling the competing demands of the spherically symmetric Coulombic interaction and cylindrical magnetic (B field) confinement. However, the best available a priori procedure for composing highly accurate AGTO sets for atoms in a strong B field [W. Zhu et al., Phys. Rev. A 90, 022504 (2014)] yields very large basis sets. Their size is problematical for use in any calculation with unfavorable computational cost scaling. Here we provide an alternative constructive procedure. It is based upon analysis of the underlying physics of atoms in B fields that allow identification of several principles for the construction of AGTO basis sets. Aided by numerical optimization and parameter fitting, followed by fine tuning of fitting parameters, we devise formulae for generating accurate AGTO basis sets in an arbitrary B field. For the hydrogen iso-electronic sequence, a set depends on B field strength, nuclear charge, and orbital quantum numbers. For multi-electron systems, the basis set formulae also include adjustment to account for orbital occupations. Tests of the new basis sets for atoms H through C (1 ≤ Z ≤ 6) and ions Li + , Be + , and B + , in a wide B field range (0 ≤ B ≤ 2000 a.u.), show an accuracy better than a few μhartree for single-electron systems and a few hundredths to a few mHs for multi-electron atoms. The relative errors are similar for different atoms and ions in a large B field range, from a few to a couple of tens of millionths, thereby confirming rather uniform accuracy across the nuclear charge Z and B field strength values. Residual basis set errors are two to three orders of magnitude smaller than the electronic correlation energies in multi-electron atoms, a signal of the usefulness of the new AGTO basis sets in correlated wavefunction or density functional calculations for atomic and molecular systems in an external strong B

Method and basis set dependence of anharmonic ground state nuclear wave functions and zero-point energies: Application to SSSH

Science.gov (United States)

Kolmann, Stephen J.; Jordan, Meredith J. T.

2010-02-01

One of the largest remaining errors in thermochemical calculations is the determination of the zero-point energy (ZPE). The fully coupled, anharmonic ZPE and ground state nuclear wave function of the SSSH radical are calculated using quantum diffusion Monte Carlo on interpolated potential energy surfaces (PESs) constructed using a variety of method and basis set combinations. The ZPE of SSSH, which is approximately 29 kJ mol-1 at the CCSD(T)/6-31G∗ level of theory, has a 4 kJ mol-1 dependence on the treatment of electron correlation. The anharmonic ZPEs are consistently 0.3 kJ mol-1 lower in energy than the harmonic ZPEs calculated at the Hartree-Fock and MP2 levels of theory, and 0.7 kJ mol-1 lower in energy at the CCSD(T)/6-31G∗ level of theory. Ideally, for sub-kJ mol-1 thermochemical accuracy, ZPEs should be calculated using correlated methods with as big a basis set as practicable. The ground state nuclear wave function of SSSH also has significant method and basis set dependence. The analysis of the nuclear wave function indicates that SSSH is localized to a single symmetry equivalent global minimum, despite having sufficient ZPE to be delocalized over both minima. As part of this work, modifications to the interpolated PES construction scheme of Collins and co-workers are presented.

Method and basis set dependence of anharmonic ground state nuclear wave functions and zero-point energies: application to SSSH.

Science.gov (United States)

Kolmann, Stephen J; Jordan, Meredith J T

2010-02-07

One of the largest remaining errors in thermochemical calculations is the determination of the zero-point energy (ZPE). The fully coupled, anharmonic ZPE and ground state nuclear wave function of the SSSH radical are calculated using quantum diffusion Monte Carlo on interpolated potential energy surfaces (PESs) constructed using a variety of method and basis set combinations. The ZPE of SSSH, which is approximately 29 kJ mol(-1) at the CCSD(T)/6-31G* level of theory, has a 4 kJ mol(-1) dependence on the treatment of electron correlation. The anharmonic ZPEs are consistently 0.3 kJ mol(-1) lower in energy than the harmonic ZPEs calculated at the Hartree-Fock and MP2 levels of theory, and 0.7 kJ mol(-1) lower in energy at the CCSD(T)/6-31G* level of theory. Ideally, for sub-kJ mol(-1) thermochemical accuracy, ZPEs should be calculated using correlated methods with as big a basis set as practicable. The ground state nuclear wave function of SSSH also has significant method and basis set dependence. The analysis of the nuclear wave function indicates that SSSH is localized to a single symmetry equivalent global minimum, despite having sufficient ZPE to be delocalized over both minima. As part of this work, modifications to the interpolated PES construction scheme of Collins and co-workers are presented.

Current-voltage curves for molecular junctions computed using all-electron basis sets

International Nuclear Information System (INIS)

Bauschlicher, Charles W.; Lawson, John W.

2006-01-01

We present current-voltage (I-V) curves computed using all-electron basis sets on the conducting molecule. The all-electron results are very similar to previous results obtained using effective core potentials (ECP). A hybrid integration scheme is used that keeps the all-electron calculations cost competitive with respect to the ECP calculations. By neglecting the coupling of states to the contacts below a fixed energy cutoff, the density matrix for the core electrons can be evaluated analytically. The full density matrix is formed by adding this core contribution to the valence part that is evaluated numerically. Expanding the definition of the core in the all-electron calculations significantly reduces the computational effort and, up to biases of about 2 V, the results are very similar to those obtained using more rigorous approaches. The convergence of the I-V curves and transmission coefficients with respect to basis set is discussed. The addition of diffuse functions is critical in approaching basis set completeness

Optimization of metabolite basis sets prior to quantitation in magnetic resonance spectroscopy: an approach based on quantum mechanics

International Nuclear Information System (INIS)

Lazariev, A; Graveron-Demilly, D; Allouche, A-R; Aubert-Frécon, M; Fauvelle, F; Piotto, M; Elbayed, K; Namer, I-J; Van Ormondt, D

2011-01-01

High-resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) is playing an increasingly important role for diagnosis. This technique enables setting up metabolite profiles of ex vivo pathological and healthy tissue. The need to monitor diseases and pharmaceutical follow-up requires an automatic quantitation of HRMAS 1 H signals. However, for several metabolites, the values of chemical shifts of proton groups may slightly differ according to the micro-environment in the tissue or cells, in particular to its pH. This hampers the accurate estimation of the metabolite concentrations mainly when using quantitation algorithms based on a metabolite basis set: the metabolite fingerprints are not correct anymore. In this work, we propose an accurate method coupling quantum mechanical simulations and quantitation algorithms to handle basis-set changes. The proposed algorithm automatically corrects mismatches between the signals of the simulated basis set and the signal under analysis by maximizing the normalized cross-correlation between the mentioned signals. Optimized chemical shift values of the metabolites are obtained. This method, QM-QUEST, provides more robust fitting while limiting user involvement and respects the correct fingerprints of metabolites. Its efficiency is demonstrated by accurately quantitating 33 signals from tissue samples of human brains with oligodendroglioma, obtained at 11.7 tesla. The corresponding chemical shift changes of several metabolites within the series are also analyzed

Optimization of metabolite basis sets prior to quantitation in magnetic resonance spectroscopy: an approach based on quantum mechanics

Science.gov (United States)

Lazariev, A.; Allouche, A.-R.; Aubert-Frécon, M.; Fauvelle, F.; Piotto, M.; Elbayed, K.; Namer, I.-J.; van Ormondt, D.; Graveron-Demilly, D.

2011-11-01

High-resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) is playing an increasingly important role for diagnosis. This technique enables setting up metabolite profiles of ex vivo pathological and healthy tissue. The need to monitor diseases and pharmaceutical follow-up requires an automatic quantitation of HRMAS 1H signals. However, for several metabolites, the values of chemical shifts of proton groups may slightly differ according to the micro-environment in the tissue or cells, in particular to its pH. This hampers the accurate estimation of the metabolite concentrations mainly when using quantitation algorithms based on a metabolite basis set: the metabolite fingerprints are not correct anymore. In this work, we propose an accurate method coupling quantum mechanical simulations and quantitation algorithms to handle basis-set changes. The proposed algorithm automatically corrects mismatches between the signals of the simulated basis set and the signal under analysis by maximizing the normalized cross-correlation between the mentioned signals. Optimized chemical shift values of the metabolites are obtained. This method, QM-QUEST, provides more robust fitting while limiting user involvement and respects the correct fingerprints of metabolites. Its efficiency is demonstrated by accurately quantitating 33 signals from tissue samples of human brains with oligodendroglioma, obtained at 11.7 tesla. The corresponding chemical shift changes of several metabolites within the series are also analyzed.

Localized orbitals vs. pseudopotential-plane waves basis sets: performances and accuracy for molecular magnetic systems

CERN Document Server

Massobrio, C

2003-01-01

Density functional theory, in combination with a) a careful choice of the exchange-correlation part of the total energy and b) localized basis sets for the electronic orbital, has become the method of choice for calculating the exchange-couplings in magnetic molecular complexes. Orbital expansion on plane waves can be seen as an alternative basis set especially suited to allow optimization of newly synthesized materials of unknown geometries. However, little is known on the predictive power of this scheme to yield quantitative values for exchange coupling constants J as small as a few hundredths of eV (50-300 cm sup - sup 1). We have used density functional theory and a plane waves basis set to calculate the exchange couplings J of three homodinuclear Cu-based molecular complexes with experimental values ranging from +40 cm sup - sup 1 to -300 cm sup - sup 1. The plane waves basis set proves as accurate as the localized basis set, thereby suggesting that this approach can be reliably employed to predict and r...

Localized orbitals vs. pseudopotential-plane waves basis sets: performances and accuracy for molecular magnetic systems

International Nuclear Information System (INIS)

Massobrio, C.; Ruiz, E.

2003-01-01

Density functional theory, in combination with a) a careful choice of the exchange-correlation part of the total energy and b) localized basis sets for the electronic orbital, has become the method of choice for calculating the exchange-couplings in magnetic molecular complexes. Orbital expansion on plane waves can be seen as an alternative basis set especially suited to allow optimization of newly synthesized materials of unknown geometries. However, little is known on the predictive power of this scheme to yield quantitative values for exchange coupling constants J as small as a few hundredths of eV (50-300 cm -1 ). We have used density functional theory and a plane waves basis set to calculate the exchange couplings J of three homodinuclear Cu-based molecular complexes with experimental values ranging from +40 cm -1 to -300 cm -1 . The plane waves basis set proves as accurate as the localized basis set, thereby suggesting that this approach can be reliably employed to predict and rationalize the magnetic properties of molecular-based materials. (author)

A Hartree–Fock study of the confined helium atom: Local and global basis set approaches

Energy Technology Data Exchange (ETDEWEB)

Young, Toby D., E-mail: tyoung@ippt.pan.pl [Zakład Metod Komputerowych, Instytut Podstawowych Prolemów Techniki Polskiej Akademia Nauk, ul. Pawińskiego 5b, 02-106 Warszawa (Poland); Vargas, Rubicelia [Universidad Autónoma Metropolitana Iztapalapa, División de Ciencias Básicas e Ingenierías, Departamento de Química, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, D.F. C.P. 09340, México (Mexico); Garza, Jorge, E-mail: jgo@xanum.uam.mx [Universidad Autónoma Metropolitana Iztapalapa, División de Ciencias Básicas e Ingenierías, Departamento de Química, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, D.F. C.P. 09340, México (Mexico)

2016-02-15

Two different basis set methods are used to calculate atomic energy within Hartree–Fock theory. The first is a local basis set approach using high-order real-space finite elements and the second is a global basis set approach using modified Slater-type orbitals. These two approaches are applied to the confined helium atom and are compared by calculating one- and two-electron contributions to the total energy. As a measure of the quality of the electron density, the cusp condition is analyzed. - Highlights: • Two different basis set methods for atomic Hartree–Fock theory. • Galerkin finite element method and modified Slater-type orbitals. • Confined atom model (helium) under small-to-extreme confinement radii. • Detailed analysis of the electron wave-function and the cusp condition.

Ab initio calculation of reaction energies. III. Basis set dependence of relative energies on the FH2 and H2CO potential energy surfaces

International Nuclear Information System (INIS)

Frisch, M.J.; Binkley, J.S.; Schaefer, H.F. III

1984-01-01

The relative energies of the stationary points on the FH 2 and H 2 CO nuclear potential energy surfaces relevant to the hydrogen atom abstraction, H 2 elimination and 1,2-hydrogen shift reactions have been examined using fourth-order Moller--Plesset perturbation theory and a variety of basis sets. The theoretical absolute zero activation energy for the F+H 2 →FH+H reaction is in better agreement with experiment than previous theoretical studies, and part of the disagreement between earlier theoretical calculations and experiment is found to result from the use of assumed rather than calculated zero-point vibrational energies. The fourth-order reaction energy for the elimination of hydrogen from formaldehyde is within 2 kcal mol -1 of the experimental value using the largest basis set considered. The qualitative features of the H 2 CO surface are unchanged by expansion of the basis set beyond the polarized triple-zeta level, but diffuse functions and several sets of polarization functions are found to be necessary for quantitative accuracy in predicted reaction and activation energies. Basis sets and levels of perturbation theory which represent good compromises between computational efficiency and accuracy are recommended

Geometrical correction for the inter- and intramolecular basis set superposition error in periodic density functional theory calculations.

Science.gov (United States)

Brandenburg, Jan Gerit; Alessio, Maristella; Civalleri, Bartolomeo; Peintinger, Michael F; Bredow, Thomas; Grimme, Stefan

2013-09-26

We extend the previously developed geometrical correction for the inter- and intramolecular basis set superposition error (gCP) to periodic density functional theory (DFT) calculations. We report gCP results compared to those from the standard Boys-Bernardi counterpoise correction scheme and large basis set calculations. The applicability of the method to molecular crystals as the main target is tested for the benchmark set X23. It consists of 23 noncovalently bound crystals as introduced by Johnson et al. (J. Chem. Phys. 2012, 137, 054103) and refined by Tkatchenko et al. (J. Chem. Phys. 2013, 139, 024705). In order to accurately describe long-range electron correlation effects, we use the standard atom-pairwise dispersion correction scheme DFT-D3. We show that a combination of DFT energies with small atom-centered basis sets, the D3 dispersion correction, and the gCP correction can accurately describe van der Waals and hydrogen-bonded crystals. Mean absolute deviations of the X23 sublimation energies can be reduced by more than 70% and 80% for the standard functionals PBE and B3LYP, respectively, to small residual mean absolute deviations of about 2 kcal/mol (corresponding to 13% of the average sublimation energy). As a further test, we compute the interlayer interaction of graphite for varying distances and obtain a good equilibrium distance and interaction energy of 6.75 Å and -43.0 meV/atom at the PBE-D3-gCP/SVP level. We fit the gCP scheme for a recently developed pob-TZVP solid-state basis set and obtain reasonable results for the X23 benchmark set and the potential energy curve for water adsorption on a nickel (110) surface.

Continuum contributions to dipole oscillator-strength sum rules for hydrogen in finite basis sets

DEFF Research Database (Denmark)

Oddershede, Jens; Ogilvie, John F.; Sauer, Stephan P. A.

2017-01-01

Calculations of the continuum contributions to dipole oscillator sum rules for hydrogen are performed using both exact and basis-set representations of the stick spectra of the continuum wave function. We show that the same results are obtained for the sum rules in both cases, but that the conver......Calculations of the continuum contributions to dipole oscillator sum rules for hydrogen are performed using both exact and basis-set representations of the stick spectra of the continuum wave function. We show that the same results are obtained for the sum rules in both cases......, but that the convergence towards the final results with increasing excitation energies included in the sum over states is slower in the basis-set cases when we use the best basis. We argue also that this conclusion most likely holds also for larger atoms or molecules....

The scientific basis for the establishment of threshold levels and dose response relationships of carcinogenesis

International Nuclear Information System (INIS)

1975-01-01

The International Atomic Energy Agency hosted a two day Symposium from 2-3 December 1974 at its Headquarters, organized by the 'International Academy for Environmental Safety and the Forum fur Wissenschaft, Wirtschaft und Politik' on the subject 'Scientific Basis for the Establishment of Threshold. Levels and Dose Response Relationships of Carcinogenesis'. Following an introductory paper by the Radiation Biology Section of the Agency on 'Radiation Carcinogenesis - Dose Response Relationship, Threshold and Risk Estimates', a series of papers dealt with this problem in chemical carcinogenesis.It was suggested that more experiments should be done using non-human primates for tests of carcinogens, especially chemicals. Preliminary experiments using monkeys with a potent carcinogen - nitrosoamine - indicate that there could possibly be a dose where no effect can be observed during the 5 year period of study. It was also pointed out that the overall cost/benefit and risk/ benefit relationships should be taken into consideration in determining limits for chemicals which are potentially carcinogenic but are used routinely by the public and industries; these considerations have been weighed in setting exposure limits for radiation

New basis set for the prediction of the specific rotation in flexible biological molecules

DEFF Research Database (Denmark)

Baranowska-Łaczkowska, Angelika; Z. Łaczkowski, Krzysztof Z. Łaczkowski; Henriksen, Christian

2016-01-01

are compared to those obtained with the (d-)aug-cc-pVXZ (X = D, T and Q) basis sets of Dunning et al. The ORP values are in good overall agreement with the aug-cc-pVTZ results making the ORP a good basis set for routine TD-DFT optical rotation calculations of conformationally flexible molecules. The results...

A two-center-oscillator-basis as an alternative set for heavy ion processes

International Nuclear Information System (INIS)

Tornow, V.; Reinhard, P.G.; Drechsel, D.

1977-01-01

The two-center-oscillator-basis, which is constructed from harmonic oscillator wave functions developing about two different centers, suffers from numerical problems at small center separations due to the overcompleteness of the set. In order to overcome these problems we admix higer oscillator wave functions before the orthogonalization, or antisymmetrization resp. This yields a numerically stable basis set at each center separation. The results obtained for the potential energy suface are comparable with the results of more elaborate models. (orig.) [de

Magnetic anisotropy basis sets for epitaxial (110) and (111) REFe2 nanofilms

International Nuclear Information System (INIS)

Bowden, G J; Martin, K N; Fox, A; Rainford, B D; Groot, P A J de

2008-01-01

Magnetic anisotropy basis sets for the cubic Laves phase rare earth intermetallic REFe 2 compounds are discussed in some detail. Such compounds can be either free standing, or thin films grown in either (110) or (111) mode using molecular beam epitaxy. For the latter, it is useful to rotate to a new coordinate system where the z-axis coincides with the growth axes of the film. In this paper, three symmetry adapted basis sets are given, for multi-pole moments up to n = 12. These sets can be used for free-standing compounds and for (110) and (111) epitaxial films. In addition, the distortion of REFe 2 films, grown on sapphire substrates, is also considered. The distortions are different for the (110) and (111) films. Strain-induced harmonic sets are given for both specific and general distortions. Finally, some predictions are made concerning the preferred direction of easy magnetization in (111) molecular beam epitaxy grown REFe 2 films

Guidelines for setting speed limits

CSIR Research Space (South Africa)

Wium, DJW

1986-02-01

Full Text Available , parking and loading manoeuvres, access to bounding properties, intersections, width of road without central median and clear roadside area. The method should result in greater uniformity in speed limits for similar circumstances as set by different...

Perspectives on setting limits for RF contact currents: a commentary.

Science.gov (United States)

Tell, Richard A; Tell, Christopher A

2018-01-15

Limits for exposure to radiofrequency (RF) contact currents are specified in the two dominant RF safety standards and guidelines developed by the Institute of Electrical and Electronics Engineers (IEEE) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP). These limits are intended to prevent RF burns when contacting RF energized objects caused by high local tissue current densities. We explain what contact currents are and review some history of the relevant limits with an emphasis on so-called "touch" contacts, i.e., contact between a person and a contact current source during touch via a very small contact area. Contact current limits were originally set on the basis of controlling the specific absorption rate resulting from the current flowing through regions of small conductive cross section within the body, such as the wrist or ankle. More recently, contact currents have been based on thresholds of perceived heating. In the latest standard from the IEEE developed for NATO, contact currents have been based on two research studies in which thresholds for perception of thermal warmth or thermal pain have been measured. Importantly, these studies maximized conductive contact between the subject and the contact current source. This factor was found to dominate the response to heating wherein high resistance contact, such as from dry skin, can result in local heating many times that from a highly conductive contact. Other factors such as electrode size and shape, frequency of the current and the physical force associated with contact are found to introduce uncertainty in threshold values when comparing data across multiple studies. Relying on studies in which the contact current is minimized for a given threshold does not result in conservative protection limits. Future efforts to develop limits on contact currents should include consideration of (1) the basis for the limits (perception, pain, tissue damage); (2) understanding of the

Distinguishing the elements of a full product basis set needs only projective measurements and classical communication

International Nuclear Information System (INIS)

Chen Pingxing; Li Chengzu

2004-01-01

Nonlocality without entanglement is an interesting field. A manifestation of quantum nonlocality without entanglement is the possible local indistinguishability of orthogonal product states. In this paper we analyze the character of operators to distinguish the elements of a full product basis set in a multipartite system, and show that distinguishing perfectly these product bases needs only local projective measurements and classical communication, and these measurements cannot damage each product basis. Employing these conclusions one can discuss local distinguishability of the elements of any full product basis set easily. Finally we discuss the generalization of these results to the locally distinguishability of the elements of incomplete product basis set

Basis of property limits for inflatable seal fluoroelastomers

International Nuclear Information System (INIS)

Sinha, N.K.; Raj, Baldev

2012-01-01

Identification of a set of governing physico-mechanical properties for inflatable seals of Prototype Fast Breeder Reactor (PFBR) and specification of their limits is described based on operating requirements, design practices and results from seal development. The limits of tensile strength, elongation at break, hardness, tear strength, fluid compatibility, compression set and specific gravity defined for the Viton GBL 200S/600S based inflatable seal formulation provide a standardized framework for regular production of reactor seals and a streamlined approach for compounding, design, manufacture and quality control. This assures significant reduction of efforts during the envisaged unification of Fast Breeder Reactor sealing based on four variations of inflatable seal compound which could result in a universal design code apart from significant gains in safety, reliability and life. The property set has potential use in Pressurized Heavy Water Reactor and Advanced Heavy Water Reactor. Inclusion of factors such as batch-to-batch variations of compound properties and their reproducibility during laboratory measurements, hot tensile behavior of fluoroelastomer, long term ageing effects and the margin of safety at the end of seal design life ensures the utility of property set in attaining its intended objective.

On the effects of basis set truncation and electron correlation in conformers of 2-hydroxy-acetamide

Science.gov (United States)

Szarecka, A.; Day, G.; Grout, P. J.; Wilson, S.

Ab initio quantum chemical calculations have been used to study the differences in energy between two gas phase conformers of the 2-hydroxy-acetamide molecule that possess intramolecular hydrogen bonding. In particular, rotation around the central C-C bond has been considered as a factor determining the structure of the hydrogen bond and stabilization of the conformer. Energy calculations include full geometiy optimization using both the restricted matrix Hartree-Fock model and second-order many-body perturbation theory with a number of commonly used basis sets. The basis sets employed ranged from the minimal STO-3G set to [`]split-valence' sets up to 6-31 G. The effects of polarization functions were also studied. The results display a strong basis set dependence.

Quality of Gaussian basis sets: direct optimization of orbital exponents by the method of conjugate gradients

International Nuclear Information System (INIS)

Kari, R.E.; Mezey, P.G.; Csizmadia, I.G.

1975-01-01

Expressions are given for calculating the energy gradient vector in the exponent space of Gaussian basis sets and a technique to optimize orbital exponents using the method of conjugate gradients is described. The method is tested on the (9/sups/5/supp/) Gaussian basis space and optimum exponents are determined for the carbon atom. The analysis of the results shows that the calculated one-electron properties converge more slowly to their optimum values than the total energy converges to its optimum value. In addition, basis sets approximating the optimum total energy very well can still be markedly improved for the prediction of one-electron properties. For smaller basis sets, this improvement does not warrant the necessary expense

Relativistic double-zeta, triple-zeta, and quadruple-zeta basis sets for the lanthanides La–Lu

NARCIS (Netherlands)

Dyall, K.G.; Gomes, A.S.P.; Visscher, L.

2010-01-01

Relativistic basis sets of double-zeta, triple-zeta, and quadruple-zeta quality have been optimized for the lanthanide elements La-Lu. The basis sets include SCF exponents for the occupied spinors and for the 6p shell, exponents of correlating functions for the valence shells (4f, 5d and 6s) and the

An approach to develop chemical intuition for atomistic electron transport calculations using basis set rotations

Energy Technology Data Exchange (ETDEWEB)

Borges, A.; Solomon, G. C. [Department of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø (Denmark)

2016-05-21

Single molecule conductance measurements are often interpreted through computational modeling, but the complexity of these calculations makes it difficult to directly link them to simpler concepts and models. Previous work has attempted to make this connection using maximally localized Wannier functions and symmetry adapted basis sets, but their use can be ambiguous and non-trivial. Starting from a Hamiltonian and overlap matrix written in a hydrogen-like basis set, we demonstrate a simple approach to obtain a new basis set that is chemically more intuitive and allows interpretation in terms of simple concepts and models. By diagonalizing the Hamiltonians corresponding to each atom in the molecule, we obtain a basis set that can be partitioned into pseudo-σ and −π and allows partitioning of the Landuaer-Büttiker transmission as well as create simple Hückel models that reproduce the key features of the full calculation. This method provides a link between complex calculations and simple concepts and models to provide intuition or extract parameters for more complex model systems.

Accurate Conformational Energy Differences of Carbohydrates: A Complete Basis Set Extrapolation

Czech Academy of Sciences Publication Activity Database

Csonka, G. I.; Kaminský, Jakub

2011-01-01

Roč. 7, č. 4 (2011), s. 988-997 ISSN 1549-9618 Institutional research plan: CEZ:AV0Z40550506 Keywords : MP2 * basis set extrapolation * saccharides Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.215, year: 2011

The oceanographic and radiological basis for the definition of high-level wastes unsuitable for dumping at sea

International Nuclear Information System (INIS)

1984-01-01

The document has taken two of the models recommended in the Group of Experts on the Scientific Aspects of Marine Pollution (GESAMP) Report in 1983 and applied them to the purpose of setting dumping rate limits into an ocean basin. This guide details the assumptions underlying oceanographic model selection, analytic solutions to the models and the radiological basis used

Density functional theory calculations of the lowest energy quintet and triplet states of model hemes: role of functional, basis set, and zero-point energy corrections.

Science.gov (United States)

Khvostichenko, Daria; Choi, Andrew; Boulatov, Roman

2008-04-24

We investigated the effect of several computational variables, including the choice of the basis set, application of symmetry constraints, and zero-point energy (ZPE) corrections, on the structural parameters and predicted ground electronic state of model 5-coordinate hemes (iron(II) porphines axially coordinated by a single imidazole or 2-methylimidazole). We studied the performance of B3LYP and B3PW91 with eight Pople-style basis sets (up to 6-311+G*) and B97-1, OLYP, and TPSS functionals with 6-31G and 6-31G* basis sets. Only hybrid functionals B3LYP, B3PW91, and B97-1 reproduced the quintet ground state of the model hemes. With a given functional, the choice of the basis set caused up to 2.7 kcal/mol variation of the quintet-triplet electronic energy gap (DeltaEel), in several cases, resulting in the inversion of the sign of DeltaEel. Single-point energy calculations with triple-zeta basis sets of the Pople (up to 6-311G++(2d,2p)), Ahlrichs (TZVP and TZVPP), and Dunning (cc-pVTZ) families showed the same trend. The zero-point energy of the quintet state was approximately 1 kcal/mol lower than that of the triplet, and accounting for ZPE corrections was crucial for establishing the ground state if the electronic energy of the triplet state was approximately 1 kcal/mol less than that of the quintet. Within a given model chemistry, effects of symmetry constraints and of a "tense" structure of the iron porphine fragment coordinated to 2-methylimidazole on DeltaEel were limited to 0.3 kcal/mol. For both model hemes the best agreement with crystallographic structural data was achieved with small 6-31G and 6-31G* basis sets. Deviation of the computed frequency of the Fe-Im stretching mode from the experimental value with the basis set decreased in the order: nonaugmented basis sets, basis sets with polarization functions, and basis sets with polarization and diffuse functions. Contraction of Pople-style basis sets (double-zeta or triple-zeta) affected the results

Geminal embedding scheme for optimal atomic basis set construction in correlated calculations

Energy Technology Data Exchange (ETDEWEB)

Sorella, S., E-mail: sorella@sissa.it [International School for Advanced Studies (SISSA), Via Beirut 2-4, 34014 Trieste, Italy and INFM Democritos National Simulation Center, Trieste (Italy); Devaux, N.; Dagrada, M., E-mail: mario.dagrada@impmc.upmc.fr [Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Université Pierre et Marie Curie, Case 115, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Mazzola, G., E-mail: gmazzola@phys.ethz.ch [Theoretische Physik, ETH Zurich, 8093 Zurich (Switzerland); Casula, M., E-mail: michele.casula@impmc.upmc.fr [CNRS and Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Université Pierre et Marie Curie, Case 115, 4 Place Jussieu, 75252 Paris Cedex 05 (France)

2015-12-28

We introduce an efficient method to construct optimal and system adaptive basis sets for use in electronic structure and quantum Monte Carlo calculations. The method is based on an embedding scheme in which a reference atom is singled out from its environment, while the entire system (atom and environment) is described by a Slater determinant or its antisymmetrized geminal power (AGP) extension. The embedding procedure described here allows for the systematic and consistent contraction of the primitive basis set into geminal embedded orbitals (GEOs), with a dramatic reduction of the number of variational parameters necessary to represent the many-body wave function, for a chosen target accuracy. Within the variational Monte Carlo method, the Slater or AGP part is determined by a variational minimization of the energy of the whole system in presence of a flexible and accurate Jastrow factor, representing most of the dynamical electronic correlation. The resulting GEO basis set opens the way for a fully controlled optimization of many-body wave functions in electronic structure calculation of bulk materials, namely, containing a large number of electrons and atoms. We present applications on the water molecule, the volume collapse transition in cerium, and the high-pressure liquid hydrogen.

Basis set effects on coupled cluster benchmarks of electronically excited states: CC3, CCSDR(3) and CC2

DEFF Research Database (Denmark)

Silva-Junior, Mario R.; Sauer, Stephan P. A.; Schreiber, Marko

2010-01-01

Vertical electronic excitation energies and one-electron properties of 28 medium-sized molecules from a previously proposed benchmark set are revisited using the augmented correlation-consistent triple-zeta aug-cc-pVTZ basis set in CC2, CCSDR(3), and CC3 calculations. The results are compared...... to those obtained previously with the smaller TZVP basis set. For each of the three coupled cluster methods, a correlation coefficient greater than 0.994 is found between the vertical excitation energies computed with the two basis sets. The deviations of the CC2 and CCSDR(3) results from the CC3 reference...... values are very similar for both basis sets, thus confirming previous conclusions on the intrinsic accuracy of CC2 and CCSDR(3). This similarity justifies the use of CC2- or CCSDR(3)-based corrections to account for basis set incompleteness in CC3 studies of vertical excitation energies. For oscillator...

Consistent structures and interactions by density functional theory with small atomic orbital basis sets.

Science.gov (United States)

Grimme, Stefan; Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas

2015-08-07

and reach that of triple-zeta AO basis set second-order perturbation theory (MP2/TZ) level at a tiny fraction of computational effort. Periodic calculations conducted for molecular crystals to test structures (including cell volumes) and sublimation enthalpies indicate very good accuracy competitive to computationally more involved plane-wave based calculations. PBEh-3c can be applied routinely to several hundreds of atoms on a single processor and it is suggested as a robust "high-speed" computational tool in theoretical chemistry and physics.

Consistent structures and interactions by density functional theory with small atomic orbital basis sets

International Nuclear Information System (INIS)

Grimme, Stefan; Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas

2015-01-01

methods and reach that of triple-zeta AO basis set second-order perturbation theory (MP2/TZ) level at a tiny fraction of computational effort. Periodic calculations conducted for molecular crystals to test structures (including cell volumes) and sublimation enthalpies indicate very good accuracy competitive to computationally more involved plane-wave based calculations. PBEh-3c can be applied routinely to several hundreds of atoms on a single processor and it is suggested as a robust “high-speed” computational tool in theoretical chemistry and physics

First-principle modelling of forsterite surface properties: Accuracy of methods and basis sets.

Science.gov (United States)

Demichelis, Raffaella; Bruno, Marco; Massaro, Francesco R; Prencipe, Mauro; De La Pierre, Marco; Nestola, Fabrizio

2015-07-15

The seven main crystal surfaces of forsterite (Mg2 SiO4 ) were modeled using various Gaussian-type basis sets, and several formulations for the exchange-correlation functional within the density functional theory (DFT). The recently developed pob-TZVP basis set provides the best results for all properties that are strongly dependent on the accuracy of the wavefunction. Convergence on the structure and on the basis set superposition error-corrected surface energy can be reached also with poorer basis sets. The effect of adopting different DFT functionals was assessed. All functionals give the same stability order for the various surfaces. Surfaces do not exhibit any major structural differences when optimized with different functionals, except for higher energy orientations where major rearrangements occur around the Mg sites at the surface or subsurface. When dispersions are not accounted for, all functionals provide similar surface energies. The inclusion of empirical dispersions raises the energy of all surfaces by a nearly systematic value proportional to the scaling factor s of the dispersion formulation. An estimation for the surface energy is provided through adopting C6 coefficients that are more suitable than the standard ones to describe O-O interactions in minerals. A 2 × 2 supercell of the most stable surface (010) was optimized. No surface reconstruction was observed. The resulting structure and surface energy show no difference with respect to those obtained when using the primitive cell. This result validates the (010) surface model here adopted, that will serve as a reference for future studies on adsorption and reactivity of water and carbon dioxide at this interface. © 2015 Wiley Periodicals, Inc.

Gaussian basis sets for use in correlated molecular calculations. IV. Calculation of static electrical response properties

International Nuclear Information System (INIS)

Woon, D.E.; Dunning, T.H. Jr.

1994-01-01

An accurate description of the electrical properties of atoms and molecules is critical for quantitative predictions of the nonlinear properties of molecules and of long-range atomic and molecular interactions between both neutral and charged species. We report a systematic study of the basis sets required to obtain accurate correlated values for the static dipole (α 1 ), quadrupole (α 2 ), and octopole (α 3 ) polarizabilities and the hyperpolarizability (γ) of the rare gas atoms He, Ne, and Ar. Several methods of correlation treatment were examined, including various orders of Moller--Plesset perturbation theory (MP2, MP3, MP4), coupled-cluster theory with and without perturbative treatment of triple excitations [CCSD, CCSD(T)], and singles and doubles configuration interaction (CISD). All of the basis sets considered here were constructed by adding even-tempered sets of diffuse functions to the correlation consistent basis sets of Dunning and co-workers. With multiply-augmented sets we find that the electrical properties of the rare gas atoms converge smoothly to values that are in excellent agreement with the available experimental data and/or previously computed results. As a further test of the basis sets presented here, the dipole polarizabilities of the F - and Cl - anions and of the HCl and N 2 molecules are also reported

Health Outcomes Survey - Limited Data Set

Data.gov (United States)

U.S. Department of Health & Human Services — The Medicare Health Outcomes Survey (HOS) limited data sets (LDS) are comprised of the entire national sample for a given 2-year cohort (including both respondents...

The Raman Spectrum of the Squarate (C4O4-2 Anion: An Ab Initio Basis Set Dependence Study

Directory of Open Access Journals (Sweden)

Miranda Sandro G. de

2002-01-01

Full Text Available The Raman excitation profile of the squarate anion, C4O4-2 , was calculated using ab initio methods at the Hartree-Fock using Linear Response Theory (LRT for six excitation frequencies: 632.5, 514.5, 488.0, 457.9, 363.8 and 337.1 nm. Five basis set functions (6-31G*, 6-31+G*, cc-pVDZ, aug-cc-pVDZ and Sadlej's polarizability basis set were investigated aiming to evaluate the performance of the 6-31G* set for numerical convergence and computational cost in relation to the larger basis sets. All basis sets reproduce the main spectroscopic features of the Raman spectrum of this anion for the excitation interval investigated. The 6-31G* basis set presented, on average, the same accuracy of numerical results as the larger sets but at a fraction of the computational cost showing that it is suitable for the theoretical investigation of the squarate dianion and its complexes and derivatives.

Influence of basis-set size on the X Σ 1 /2 +2 , A Π 1 /2 2 , A Π 3 /2 2 , and B Σ 1 /2 +2 potential-energy curves, A Π 3 /2 2 vibrational energies, and D1 and D2 line shapes of Rb+He

Science.gov (United States)

Blank, L. Aaron; Sharma, Amit R.; Weeks, David E.

2018-03-01

The X Σ 1 /2 +2 , A Π 1 /2 2 , A Π 3 /2 2 , and B2Σ1/2 + potential-energy curves for Rb+He are computed at the spin-orbit multireference configuration interaction level of theory using a hierarchy of Gaussian basis sets at the double-zeta (DZ), triple-zeta (TZ), and quadruple-zeta (QZ) levels of valence quality. Counterpoise and Davidson-Silver corrections are employed to remove basis-set superposition error and ameliorate size-consistency error. An extrapolation is performed to obtain a final set of potential-energy curves in the complete basis-set (CBS) limit. This yields four sets of systematically improved X Σ 1 /2 +2 , A Π 1 /2 2 , A Π 3 /2 2 , and B2Σ1/2 + potential-energy curves that are used to compute the A Π 3 /2 2 bound vibrational energies, the position of the D2 blue satellite peak, and the D1 and D2 pressure broadening and shifting coefficients, at the DZ, TZ, QZ, and CBS levels. Results are compared with previous calculations and experimental observation.

submitter Searches for New Physics, involving Top Quarks, Dark Matter and the Higgs Bosons, at the ATLAS, CDF and Fermi-LAT Particle Experiments, and a description of a new limit re-interpretation tool, Basis-Limits

CERN Document Server

Rao, Kanury Kanishka

Searches for new physics are presented in the lepton + jets channel at the CDF and ATLAS experiments. At CDF, we search for exotic quarks that couple to dark matter, new particle resonances in top-quark pairs, a Z' boson decaying quarks, and a two-Higgs doublet model. At ATLAS, we search for fourth generation down-type quarks, new particle resonances in top-quark pairs, and a multi-Higgs boson cascade. A novel methodology, Basis-limits, which allows for re-interpretation of experimental limits is presented. Basis-limits is used to extend ATLAS limits on fourth generation quarks to set limits on a new vector-like quark for all its decay modes. Finally, a spatial analysis of the gamma-ray excess, seen by the Fermi-LAT experiment, is performed. We find the location of the excess to be consistent with a dark matter halo at the Galactic center as the source.

Radiobiological basis for setting neutron radiation safety standards

International Nuclear Information System (INIS)

Straume, T.

1985-01-01

Present neutron standards, adopted more than 20 yr ago from a weak radiobiological data base, have been in doubt for a number of years and are currently under challenge. Moreover, recent dosimetric re-evaluations indicate that Hiroshima neutron doses may have been much lower than previously thought, suggesting that direct data for neutron-induced cancer in humans may in fact not be available. These recent developments make it urgent to determine the extent to which neutron cancer risk in man can be estimated from data that are available. Two approaches are proposed here that are anchored in particularly robust epidemiological and experimental data and appear most likely to provide reliable estimates of neutron cancer risk in man. The first approach uses gamma-ray dose-response relationships for human carcinogenesis, available from Nagasaki (Hiroshima data are also considered), together with highly characterized neutron and gamma-ray data for human cytogenetics. When tested against relevant experimental data, this approach either adequately predicts or somewhat overestimates neutron tumorigenesis (and mutagenesis) in animals. The second approach also uses the Nagasaki gamma-ray cancer data, but together with neutron RBEs from animal tumorigenesis studies. Both approaches give similar results and provide a basis for setting neutron radiation safety standards. They appear to be an improvement over previous approaches, including those that rely on highly uncertain maximum neutron RBEs and unnecessary extrapolations of gamma-ray data to very low doses. Results suggest that, at the presently accepted neutron dose limit of 0.5 rad/yr, the cancer mortality risk to radiation workers is not very different from accidental mortality risks to workers in various nonradiation occupations

Strategies for reducing basis set superposition error (BSSE) in O/AU and O/Ni

KAUST Repository

Shuttleworth, I.G.

2015-01-01

© 2015 Elsevier Ltd. All rights reserved. The effect of basis set superposition error (BSSE) and effective strategies for the minimisation have been investigated using the SIESTA-LCAO DFT package. Variation of the energy shift parameter ΔEPAO has been shown to reduce BSSE for bulk Au and Ni and across their oxygenated surfaces. Alternative strategies based on either the expansion or contraction of the basis set have been shown to be ineffective in reducing BSSE. Comparison of the binding energies for the surface systems obtained using LCAO were compared with BSSE-free plane wave energies.

Strategies for reducing basis set superposition error (BSSE) in O/AU and O/Ni

KAUST Repository

Shuttleworth, I.G.

2015-11-01

© 2015 Elsevier Ltd. All rights reserved. The effect of basis set superposition error (BSSE) and effective strategies for the minimisation have been investigated using the SIESTA-LCAO DFT package. Variation of the energy shift parameter ΔEPAO has been shown to reduce BSSE for bulk Au and Ni and across their oxygenated surfaces. Alternative strategies based on either the expansion or contraction of the basis set have been shown to be ineffective in reducing BSSE. Comparison of the binding energies for the surface systems obtained using LCAO were compared with BSSE-free plane wave energies.

Out-of-Core Computations of High-Resolution Level Sets by Means of Code Transformation

DEFF Research Database (Denmark)

Christensen, Brian Bunch; Nielsen, Michael Bang; Museth, Ken

2012-01-01

We propose a storage efficient, fast and parallelizable out-of-core framework for streaming computations of high resolution level sets. The fundamental techniques are skewing and tiling transformations of streamed level set computations which allow for the combination of interface propagation, re...... computations are now CPU bound and consequently the overall performance is unaffected by disk latency and bandwidth limitations. We demonstrate this with several benchmark tests that show sustained out-of-core throughputs close to that of in-core level set simulations....

Ab initio localized basis set study of structural parameters and elastic properties of HfO2 polymorphs

International Nuclear Information System (INIS)

Caravaca, M A; Casali, R A

2005-01-01

The SIESTA approach based on pseudopotentials and a localized basis set is used to calculate the electronic, elastic and equilibrium properties of P 2 1 /c, Pbca, Pnma, Fm3m, P4 2 nmc and Pa3 phases of HfO 2 . Using separable Troullier-Martins norm-conserving pseudopotentials which include partial core corrections for Hf, we tested important physical properties as a function of the basis set size, grid size and cut-off ratio of the pseudo-atomic orbitals (PAOs). We found that calculations in this oxide with the LDA approach and using a minimal basis set (simple zeta, SZ) improve calculated phase transition pressures with respect to the double-zeta basis set and LDA (DZ-LDA), and show similar accuracy to that determined with the PPPW and GGA approach. Still, the equilibrium volumes and structural properties calculated with SZ-LDA compare better with experiments than the GGA approach. The bandgaps and elastic and structural properties calculated with DZ-LDA are accurate in agreement with previous state of the art ab initio calculations and experimental evidence and cannot be improved with a polarized basis set. These calculated properties show low sensitivity to the PAO localization parameter range between 40 and 100 meV. However, this is not true for the relative energy, which improves upon decrease of the mentioned parameter. We found a non-linear behaviour in the lattice parameters with pressure in the P 2 1 /c phase, showing a discontinuity of the derivative of the a lattice parameter with respect to external pressure, as found in experiments. The common enthalpy values calculated with the minimal basis set give pressure transitions of 3.3 and 10.8?GPa for P2 1 /c → Pbca and Pbca → Pnma, respectively, in accordance with different high pressure experimental values

Basis for limiting exposure to ionizing radiation

International Nuclear Information System (INIS)

Bush, W.R.

1979-07-01

In view of the uncertainty about the size of the risk from radiation, it is assumed that all doses are potentially harmful with the probability of harm proportional to the dose, without threshold. Canada participates in the work of UNSCEAR, and the Canadian Atomic Energy Control Board follows the recommendations of the International Commission on Radiological Protection in setting its dose limits, encouraging the application of the ALARA (as low as reasonably achievable) concept through its licensing and compliance activities

Nuclear-electronic orbital reduced explicitly correlated Hartree-Fock approach: Restricted basis sets and open-shell systems

International Nuclear Information System (INIS)

Brorsen, Kurt R.; Sirjoosingh, Andrew; Pak, Michael V.; Hammes-Schiffer, Sharon

2015-01-01

The nuclear electronic orbital (NEO) reduced explicitly correlated Hartree-Fock (RXCHF) approach couples select electronic orbitals to the nuclear orbital via Gaussian-type geminal functions. This approach is extended to enable the use of a restricted basis set for the explicitly correlated electronic orbitals and an open-shell treatment for the other electronic orbitals. The working equations are derived and the implementation is discussed for both extensions. The RXCHF method with a restricted basis set is applied to HCN and FHF − and is shown to agree quantitatively with results from RXCHF calculations with a full basis set. The number of many-particle integrals that must be calculated for these two molecules is reduced by over an order of magnitude with essentially no loss in accuracy, and the reduction factor will increase substantially for larger systems. Typically, the computational cost of RXCHF calculations with restricted basis sets will scale in terms of the number of basis functions centered on the quantum nucleus and the covalently bonded neighbor(s). In addition, the RXCHF method with an odd number of electrons that are not explicitly correlated to the nuclear orbital is implemented using a restricted open-shell formalism for these electrons. This method is applied to HCN + , and the nuclear densities are in qualitative agreement with grid-based calculations. Future work will focus on the significance of nonadiabatic effects in molecular systems and the further enhancement of the NEO-RXCHF approach to accurately describe such effects

Nuclear-electronic orbital reduced explicitly correlated Hartree-Fock approach: Restricted basis sets and open-shell systems

Energy Technology Data Exchange (ETDEWEB)

Brorsen, Kurt R.; Sirjoosingh, Andrew; Pak, Michael V.; Hammes-Schiffer, Sharon, E-mail: shs3@illinois.edu [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Ave., Urbana, Illinois 61801 (United States)

2015-06-07

The nuclear electronic orbital (NEO) reduced explicitly correlated Hartree-Fock (RXCHF) approach couples select electronic orbitals to the nuclear orbital via Gaussian-type geminal functions. This approach is extended to enable the use of a restricted basis set for the explicitly correlated electronic orbitals and an open-shell treatment for the other electronic orbitals. The working equations are derived and the implementation is discussed for both extensions. The RXCHF method with a restricted basis set is applied to HCN and FHF{sup −} and is shown to agree quantitatively with results from RXCHF calculations with a full basis set. The number of many-particle integrals that must be calculated for these two molecules is reduced by over an order of magnitude with essentially no loss in accuracy, and the reduction factor will increase substantially for larger systems. Typically, the computational cost of RXCHF calculations with restricted basis sets will scale in terms of the number of basis functions centered on the quantum nucleus and the covalently bonded neighbor(s). In addition, the RXCHF method with an odd number of electrons that are not explicitly correlated to the nuclear orbital is implemented using a restricted open-shell formalism for these electrons. This method is applied to HCN{sup +}, and the nuclear densities are in qualitative agreement with grid-based calculations. Future work will focus on the significance of nonadiabatic effects in molecular systems and the further enhancement of the NEO-RXCHF approach to accurately describe such effects.

The Bethe Sum Rule and Basis Set Selection in the Calculation of Generalized Oscillator Strengths

DEFF Research Database (Denmark)

Cabrera-Trujillo, Remigio; Sabin, John R.; Oddershede, Jens

1999-01-01

Fulfillment of the Bethe sum rule may be construed as a measure of basis set quality for atomic and molecular properties involving the generalized oscillator strength distribution. It is first shown that, in the case of a complete basis, the Bethe sum rule is fulfilled exactly in the random phase...

High-level waste tank farm set point document

International Nuclear Information System (INIS)

Anthony, J.A. III.

1995-01-01

Setpoints for nuclear safety-related instrumentation are required for actions determined by the design authorization basis. Minimum requirements need to be established for assuring that setpoints are established and held within specified limits. This document establishes the controlling methodology for changing setpoints of all classifications. The instrumentation under consideration involve the transfer, storage, and volume reduction of radioactive liquid waste in the F- and H-Area High-Level Radioactive Waste Tank Farms. The setpoint document will encompass the PROCESS AREA listed in the Safety Analysis Report (SAR) (DPSTSA-200-10 Sup 18) which includes the diversion box HDB-8 facility. In addition to the PROCESS AREAS listed in the SAR, Building 299-H and the Effluent Transfer Facility (ETF) are also included in the scope

High-level waste tank farm set point document

Energy Technology Data Exchange (ETDEWEB)

Anthony, J.A. III

1995-01-15

Setpoints for nuclear safety-related instrumentation are required for actions determined by the design authorization basis. Minimum requirements need to be established for assuring that setpoints are established and held within specified limits. This document establishes the controlling methodology for changing setpoints of all classifications. The instrumentation under consideration involve the transfer, storage, and volume reduction of radioactive liquid waste in the F- and H-Area High-Level Radioactive Waste Tank Farms. The setpoint document will encompass the PROCESS AREA listed in the Safety Analysis Report (SAR) (DPSTSA-200-10 Sup 18) which includes the diversion box HDB-8 facility. In addition to the PROCESS AREAS listed in the SAR, Building 299-H and the Effluent Transfer Facility (ETF) are also included in the scope.

Consistent gaussian basis sets of double- and triple-zeta valence with polarization quality of the fifth period for solid-state calculations.

Science.gov (United States)

Laun, Joachim; Vilela Oliveira, Daniel; Bredow, Thomas

2018-02-22

Consistent basis sets of double- and triple-zeta valence with polarization quality for the fifth period have been derived for periodic quantum-chemical solid-state calculations with the crystalline-orbital program CRYSTAL. They are an extension of the pob-TZVP basis sets, and are based on the full-relativistic effective core potentials (ECPs) of the Stuttgart/Cologne group and on the def2-SVP and def2-TZVP valence basis of the Ahlrichs group. We optimized orbital exponents and contraction coefficients to supply robust and stable self-consistent field (SCF) convergence for a wide range of different compounds. The computed crystal structures are compared to those obtained with standard basis sets available from the CRYSTAL basis set database. For the applied hybrid density functional PW1PW, the average deviations of calculated lattice constants from experimental references are smaller with pob-DZVP and pob-TZVP than with standard basis sets. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Ecotoxicological assessments and the setting of limit values for chemicals in the environment

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-11-01

The Committee on the Setting of Limit Values for Chemicals held its first open conference in Denmark in March 1992 at Mogenstrup Kro, Zealand. The conference proceedings were entitled `Risk Management and Risk Assessment in Different Sectors in Denmark`. The conference focused on risk assessment and the setting of limit values for chemicals in connection with human exposure to chemicals. The conference held in January 1996, which is covered by the present proceedings, dealt with the exposure of the environment to chemicals and the state-of-the-art as well as perspectives of ecotoxicological research. Special emphasis was placed on the illustration and discussion of the problems that have to be solved in order to secure satisfactory levels of protection of soil and aquatic environments in connection with exposure to chemicals. Also, problems connected with exposure through the atmosphere were discussed and exemplified by the work on the setting of limit values for tropospheric ozone. Furthermore, the global problems pertaining to what is believed to be the greenhouse effect and the degradation of the stratospheric ozone layer as well as the damage to crops caused by ozone were mentioned. (au)

Ab initio localized basis set study of structural parameters and elastic properties of HfO{sub 2} polymorphs

Energy Technology Data Exchange (ETDEWEB)

Caravaca, M A [Facultad de Ingenieria, Universidad Nacional del Nordeste, Avenida Las Heras 727, 3500-Resistencia (Argentina); Casali, R A [Facultad de Ciencias Exactas y Naturales y Agrimensura, Universidad Nacional del Nordeste, Avenida Libertad, 5600-Corrientes (Argentina)

2005-09-21

The SIESTA approach based on pseudopotentials and a localized basis set is used to calculate the electronic, elastic and equilibrium properties of P 2{sub 1}/c, Pbca, Pnma, Fm3m, P4{sub 2}nmc and Pa3 phases of HfO{sub 2}. Using separable Troullier-Martins norm-conserving pseudopotentials which include partial core corrections for Hf, we tested important physical properties as a function of the basis set size, grid size and cut-off ratio of the pseudo-atomic orbitals (PAOs). We found that calculations in this oxide with the LDA approach and using a minimal basis set (simple zeta, SZ) improve calculated phase transition pressures with respect to the double-zeta basis set and LDA (DZ-LDA), and show similar accuracy to that determined with the PPPW and GGA approach. Still, the equilibrium volumes and structural properties calculated with SZ-LDA compare better with experiments than the GGA approach. The bandgaps and elastic and structural properties calculated with DZ-LDA are accurate in agreement with previous state of the art ab initio calculations and experimental evidence and cannot be improved with a polarized basis set. These calculated properties show low sensitivity to the PAO localization parameter range between 40 and 100 meV. However, this is not true for the relative energy, which improves upon decrease of the mentioned parameter. We found a non-linear behaviour in the lattice parameters with pressure in the P 2{sub 1}/c phase, showing a discontinuity of the derivative of the a lattice parameter with respect to external pressure, as found in experiments. The common enthalpy values calculated with the minimal basis set give pressure transitions of 3.3 and 10.8?GPa for P2{sub 1}/c {yields} Pbca and Pbca {yields} Pnma, respectively, in accordance with different high pressure experimental values.

Basis set approach in the constrained interpolation profile method

International Nuclear Information System (INIS)

Utsumi, T.; Koga, J.; Yabe, T.; Ogata, Y.; Matsunaga, E.; Aoki, T.; Sekine, M.

2003-07-01

We propose a simple polynomial basis-set that is easily extendable to any desired higher-order accuracy. This method is based on the Constrained Interpolation Profile (CIP) method and the profile is chosen so that the subgrid scale solution approaches the real solution by the constraints from the spatial derivative of the original equation. Thus the solution even on the subgrid scale becomes consistent with the master equation. By increasing the order of the polynomial, this solution quickly converges. 3rd and 5th order polynomials are tested on the one-dimensional Schroedinger equation and are proved to give solutions a few orders of magnitude higher in accuracy than conventional methods for lower-lying eigenstates. (author)

A risk-informed basis for establishing non-fixed surface contamination limits for spent fuel transportation casks

International Nuclear Information System (INIS)

Rawl, R.R.; Eckerman, K.F.; Bogard, J.S.; Cook, J.R.

2004-01-01

The current limits for non-fixed contamination on packages used to transport radioactive materials were introduced in the 1961 edition of the International Atomic Energy Agency (IAEA) transport regulations and were based on radiation protection guidance and practices in use at that time. The limits were based on exposure scenarios leading to intakes of radionuclides by inhalation and external irradiation of the hands. These considerations are collectively referred to as the Fairbairn model. Although formulated over 40 years ago, the model remains unchanged and is still the basis of current regulatory-derived limits on package non-fixed surface contamination. There can also be doses that while not resulting directly from the contamination, are strongly influenced by and attributable to transport regulatory requirements for contamination control. For example, actions necessary to comply with the current derived limits for light-water-reactor (LWR) spent nuclear fuel (SNF) casks can result in significant external doses to workers. This is due to the relatively high radiation levels around the loaded casks, where workers must function during the measurement of contamination levels and while decontaminating the cask. In order to optimize the total dose received due to compliance with cask contamination levels, it is necessary to take into account all the doses that vary as a result of the regulatory limit. Limits for non-fixed surface contamination on spent fuel casks should be established by using a model that considers and optimizes the appropriate exposure scenarios both in the workplace and in the public environment. A risk-informed approach is needed to ensure optimal use of personnel and material resources for SNF-based packaging operations. This paper is a summary of a study sponsored by the US Nuclear Regulatory Commission and performed by Oak Ridge National Laboratory that examined the dose implications for removable surface contamination limits on spent fuel

A method of setting limits for the purpose of quality assurance

International Nuclear Information System (INIS)

Sanghangthum, Taweap; Suriyapee, Sivalee; Kim, Gwe-Ya; Pawlicki, Todd

2013-01-01

The result from any assurance measurement needs to be checked against some limits for acceptability. There are two types of limits; those that define clinical acceptability (action limits) and those that are meant to serve as a warning that the measurement is close to the action limits (tolerance limits). Currently, there is no standard procedure to set these limits. In this work, we propose an operational procedure to set tolerance limits and action limits. The approach to establish the limits is based on techniques of quality engineering using control charts and a process capability index. The method is different for tolerance limits and action limits with action limits being categorized into those that are specified and unspecified. The procedure is to first ensure process control using the I-MR control charts. Then, the tolerance limits are set equal to the control chart limits on the I chart. Action limits are determined using the C pm process capability index with the requirements that the process must be in-control. The limits from the proposed procedure are compared to an existing or conventional method. Four examples are investigated: two of volumetric modulated arc therapy (VMAT) point dose quality assurance (QA) and two of routine linear accelerator output QA. The tolerance limits range from about 6% larger to 9% smaller than conventional action limits for VMAT QA cases. For the linac output QA, tolerance limits are about 60% smaller than conventional action limits. The operational procedure describe in this work is based on established quality management tools and will provide a systematic guide to set up tolerance and action limits for different equipment and processes. (paper)

Predicting Pt-195 NMR chemical shift using new relativistic all-electron basis set

NARCIS (Netherlands)

Paschoal, D.; Fonseca Guerra, C.; de Oliveira, M.A.L.; Ramalho, T.C.; Dos Santos, H.F.

2016-01-01

Predicting NMR properties is a valuable tool to assist the experimentalists in the characterization of molecular structure. For heavy metals, such as Pt-195, only a few computational protocols are available. In the present contribution, all-electron Gaussian basis sets, suitable to calculate the

Dynamic sensitivity analysis of long running landslide models through basis set expansion and meta-modelling

Science.gov (United States)

Rohmer, Jeremy

2016-04-01

Predicting the temporal evolution of landslides is typically supported by numerical modelling. Dynamic sensitivity analysis aims at assessing the influence of the landslide properties on the time-dependent predictions (e.g., time series of landslide displacements). Yet two major difficulties arise: 1. Global sensitivity analysis require running the landslide model a high number of times (> 1000), which may become impracticable when the landslide model has a high computation time cost (> several hours); 2. Landslide model outputs are not scalar, but function of time, i.e. they are n-dimensional vectors with n usually ranging from 100 to 1000. In this article, I explore the use of a basis set expansion, such as principal component analysis, to reduce the output dimensionality to a few components, each of them being interpreted as a dominant mode of variation in the overall structure of the temporal evolution. The computationally intensive calculation of the Sobol' indices for each of these components are then achieved through meta-modelling, i.e. by replacing the landslide model by a "costless-to-evaluate" approximation (e.g., a projection pursuit regression model). The methodology combining "basis set expansion - meta-model - Sobol' indices" is then applied to the La Frasse landslide to investigate the dynamic sensitivity analysis of the surface horizontal displacements to the slip surface properties during the pore pressure changes. I show how to extract information on the sensitivity of each main modes of temporal behaviour using a limited number (a few tens) of long running simulations. In particular, I identify the parameters, which trigger the occurrence of a turning point marking a shift between a regime of low values of landslide displacements and one of high values.

On compactoid and limited sets in non-Archimedean locally convex ...

African Journals Online (AJOL)

In [2] and [3] spaces in which every bounded subset is a compactoid was studied. Every compactoid set is limited but the converse is not true [3]. In this paper, we shall study some spaces in which every limited set is compactoid. Journal of the Nigerian Association of Mathematical Physics Vol. 10 2006: pp. 571-574.

A Within-Group Analysis of African American Mothers’ Authoritarian Attitudes, Limit-Setting and Children's Self-Regulation

Science.gov (United States)

LeCuyer, Elizabeth A.; Swanson, Dena Phillips

2016-01-01

Research suggests that higher levels of authoritarian parenting exist in African American (AA) families than in European American (EA) families, and that authoritarian attitudes may be associated with more positive outcomes in AA families than EA families. However, less is known about authoritarian attitudes and children's development within AA families. This within-group study of 50 African American mothers and their 3-year-old children examined associations between maternal authoritarian attitudes, observed maternal limit-setting strategies, and children's self-regulation during a limit-setting interaction. The findings indicate that while AA families may hold more authoritarian attitudes than EA families, the direction of effect of authoritarian attitudes on children's outcomes appears to be the same in both ethnic groups. In this sample, when examining AA authoritarian attitudes relative to those of other AA mothers, less or lower authoritarian attitudes were associated with authoritative limit-setting behavior (firm limits within the context of overall warmth and responsiveness) and better children's self-regulation. PMID:28408794

A Within-Group Analysis of African American Mothers' Authoritarian Attitudes, Limit-Setting and Children's Self-Regulation.

Science.gov (United States)

LeCuyer, Elizabeth A; Swanson, Dena Phillips

2017-03-01

Research suggests that higher levels of authoritarian parenting exist in African American (AA) families than in European American (EA) families, and that authoritarian attitudes may be associated with more positive outcomes in AA families than EA families. However, less is known about authoritarian attitudes and children's development within AA families. This within-group study of 50 African American mothers and their 3-year-old children examined associations between maternal authoritarian attitudes, observed maternal limit-setting strategies, and children's self-regulation during a limit-setting interaction. The findings indicate that while AA families may hold more authoritarian attitudes than EA families, the direction of effect of authoritarian attitudes on children's outcomes appears to be the same in both ethnic groups. In this sample, when examining AA authoritarian attitudes relative to those of other AA mothers, less or lower authoritarian attitudes were associated with authoritative limit-setting behavior (firm limits within the context of overall warmth and responsiveness) and better children's self-regulation.

Comparison of some dispersion-corrected and traditional functionals with CCSD(T) and MP2 ab initio methods: Dispersion, induction, and basis set superposition error

Science.gov (United States)

Roy, Dipankar; Marianski, Mateusz; Maitra, Neepa T.; Dannenberg, J. J.

2012-10-01

We compare dispersion and induction interactions for noble gas dimers and for Ne, methane, and 2-butyne with HF and LiF using a variety of functionals (including some specifically parameterized to evaluate dispersion interactions) with ab initio methods including CCSD(T) and MP2. We see that inductive interactions tend to enhance dispersion and may be accompanied by charge-transfer. We show that the functionals do not generally follow the expected trends in interaction energies, basis set superposition errors (BSSE), and interaction distances as a function of basis set size. The functionals parameterized to treat dispersion interactions often overestimate these interactions, sometimes by quite a lot, when compared to higher level calculations. Which functionals work best depends upon the examples chosen. The B3LYP and X3LYP functionals, which do not describe pure dispersion interactions, appear to describe dispersion mixed with induction about as accurately as those parametrized to treat dispersion. We observed significant differences in high-level wavefunction calculations in a basis set larger than those used to generate the structures in many of the databases. We discuss the implications for highly parameterized functionals based on these databases, as well as the use of simple potential energy for fitting the parameters rather than experimentally determinable thermodynamic state functions that involve consideration of vibrational states.

On the Convergence of the ccJ-pVXZ and pcJ-n Basis Sets in CCSD Calculations of Nuclear Spin-Spin Coupling Constants

DEFF Research Database (Denmark)

Faber, Rasmus; Sauer, Stephan P. A.

2018-01-01

The basis set convergence of nuclear spin-spin coupling constants (SSCC) calculated at the coupled cluster singles and doubles (CCSD) level has been investigated for ten difficult molecules. Eight of the molecules contain fluorine atoms and nine contain double or triple bonds. Results obtained...

Evaluating healthcare priority setting at the meso level: A thematic review of empirical literature

Science.gov (United States)

Waithaka, Dennis; Tsofa, Benjamin; Barasa, Edwine

2018-01-01

Background: Decentralization of health systems has made sub-national/regional healthcare systems the backbone of healthcare delivery. These regions are tasked with the difficult responsibility of determining healthcare priorities and resource allocation amidst scarce resources. We aimed to review empirical literature that evaluated priority setting practice at the meso (sub-national) level of health systems. Methods: We systematically searched PubMed, ScienceDirect and Google scholar databases and supplemented these with manual searching for relevant studies, based on the reference list of selected papers. We only included empirical studies that described and evaluated, or those that only evaluated priority setting practice at the meso-level. A total of 16 papers were identified from LMICs and HICs. We analyzed data from the selected papers by thematic review. Results: Few studies used systematic priority setting processes, and all but one were from HICs. Both formal and informal criteria are used in priority-setting, however, informal criteria appear to be more perverse in LMICs compared to HICs. The priority setting process at the meso-level is a top-down approach with minimal involvement of the community. Accountability for reasonableness was the most common evaluative framework as it was used in 12 of the 16 studies. Efficiency, reallocation of resources and options for service delivery redesign were the most common outcome measures used to evaluate priority setting. Limitations: Our study was limited by the fact that there are very few empirical studies that have evaluated priority setting at the meso-level and there is likelihood that we did not capture all the studies. Conclusions: Improving priority setting practices at the meso level is crucial to strengthening health systems. This can be achieved through incorporating and adapting systematic priority setting processes and frameworks to the context where used, and making considerations of both process

An editor for the maintenance and use of a bank of contracted Gaussian basis set functions

International Nuclear Information System (INIS)

Taurian, O.E.

1984-01-01

A bank of basis sets to be used in ab-initio calculations has been created. The bases are sets of contracted Gaussian type orbitals to be used as input to any molecular integral package. In this communication we shall describe the organization of the bank and a portable editor program which was designed for its maintenance and use. This program is operated by commands and it may be used to obtain any kind of information about the bases in the bank as well as to produce output to be directly used as input for different integral programs. The editor may also be used to format basis sets in the conventional way utilized in publications, as well as to generate a complete, or partial, manual of the contents of the bank if so desired. (orig.)

Ethical considerations in HIV prevention and vaccine research in resource-limited settings.

Science.gov (United States)

Garner, Samual A; Anude, Chuka J; Adams, Elizabeth; Dawson, Liza

2014-09-01

HIV prevention research has been facing increasing ethical and operational challenges. Factors influencing the design and conduct of HIV prevention trials include a rapidly changing evidence base, new biomedical prevention methods and modalities being tested, a large diversity of countries, sites and populations affected by HIV and participating in trials, and challenges of developing and making available products that will be feasible and affordable for at-risk populations. To discuss these challenges, a meeting, Ethical considerations around novel combination prevention modalities in HIV prevention and vaccine trials in resource-limited settings, was convened by NIH/NIAID/Division of AIDS on April 22-23, 2013. Several themes emerged from the meeting: (1) because of both trial design and ethical complexities, choosing prevention packages and designing combination prevention research trials will need to be evaluated on a case by case basis in different clinical trials, countries, and health systems; (2) multilevel stakeholder engagement from the beginning is vital to a fair and transparent process and also to designing ethical and relevant trials; (3) research should generally be responsive to a host country's needs, and sponsors and stakeholders should work together to address potential barriers to future access; and finally, (4) another meeting including a broader group of stakeholders is needed to address many of the outstanding ethical issues raised by this meeting. We offer an overview of the meeting and the key discussion points and recommendations to help guide the design and conduct of future HIV prevention and vaccine research in resource-limited settings.

Change in Vitamin D Levels Occurs Early after Antiretroviral Therapy Initiation and Depends on Treatment Regimen in Resource-Limited Settings

Science.gov (United States)

Havers, Fiona P.; Detrick, Barbara; Cardoso, Sandra W.; Berendes, Sima; Lama, Javier R.; Sugandhavesa, Patcharaphan; Mwelase, Noluthando H.; Campbell, Thomas B.; Gupta, Amita

2014-01-01

Study Background Vitamin D has wide-ranging effects on the immune system, and studies suggest that low serum vitamin D levels are associated with worse clinical outcomes in HIV. Recent studies have identified an interaction between antiretrovirals used to treat HIV and reduced serum vitamin D levels, but these studies have been done in North American and European populations. Methods Using a prospective cohort study design nested in a multinational clinical trial, we examined the effect of three combination antiretroviral (cART) regimens on serum vitamin D levels in 270 cART-naïve, HIV-infected adults in nine diverse countries, (Brazil, Haiti, Peru, Thailand, India, Malawi, South Africa, Zimbabwe and the United States). We evaluated the change between baseline serum vitamin D levels and vitamin D levels 24 and 48 weeks after cART initiation. Results Serum vitamin D levels decreased significantly from baseline to 24 weeks among those randomized to efavirenz/lamivudine/zidovudine (mean change: −7.94 [95% Confidence Interval (CI) −10.42, −5.54] ng/ml) and efavirenz/emtricitabine/tenofovir-DF (mean change: −6.66 [95% CI −9.40, −3.92] ng/ml) when compared to those randomized to atazanavir/emtricitabine/didanosine-EC (mean change: −2.29 [95% CI –4.83, 0.25] ng/ml). Vitamin D levels did not change significantly between week 24 and 48. Other factors that significantly affected serum vitamin D change included country (p<0.001), season (p<0.001) and baseline vitamin D level (p<0.001). Conclusion Efavirenz-containing cART regimens adversely affected vitamin D levels in patients from economically, geographically and racially diverse resource-limited settings. This effect was most pronounced early after cART initiation. Research is needed to define the role of Vitamin D supplementation in HIV care. PMID:24752177

Atomic Cholesky decompositions: A route to unbiased auxiliary basis sets for density fitting approximation with tunable accuracy and efficiency

Science.gov (United States)

Aquilante, Francesco; Gagliardi, Laura; Pedersen, Thomas Bondo; Lindh, Roland

2009-04-01

Cholesky decomposition of the atomic two-electron integral matrix has recently been proposed as a procedure for automated generation of auxiliary basis sets for the density fitting approximation [F. Aquilante et al., J. Chem. Phys. 127, 114107 (2007)]. In order to increase computational performance while maintaining accuracy, we propose here to reduce the number of primitive Gaussian functions of the contracted auxiliary basis functions by means of a second Cholesky decomposition. Test calculations show that this procedure is most beneficial in conjunction with highly contracted atomic orbital basis sets such as atomic natural orbitals, and that the error resulting from the second decomposition is negligible. We also demonstrate theoretically as well as computationally that the locality of the fitting coefficients can be controlled by means of the decomposition threshold even with the long-ranged Coulomb metric. Cholesky decomposition-based auxiliary basis sets are thus ideally suited for local density fitting approximations.

Performance assessment of density functional methods with Gaussian and Slater basis sets using 7σ orbital momentum distributions of N2O

Science.gov (United States)

Wang, Feng; Pang, Wenning; Duffy, Patrick

2012-12-01

Performance of a number of commonly used density functional methods in chemistry (B3LYP, Bhandh, BP86, PW91, VWN, LB94, PBe0, SAOP and X3LYP and the Hartree-Fock (HF) method) has been assessed using orbital momentum distributions of the 7σ orbital of nitrous oxide (NNO), which models electron behaviour in a chemically significant region. The density functional methods are combined with a number of Gaussian basis sets (Pople's 6-31G*, 6-311G**, DGauss TZVP and Dunning's aug-cc-pVTZ as well as even-tempered Slater basis sets, namely, et-DZPp, et-QZ3P, et-QZ+5P and et-pVQZ). Orbital momentum distributions of the 7σ orbital in the ground electronic state of NNO, which are obtained from a Fourier transform into momentum space from single point electronic calculations employing the above models, are compared with experimental measurement of the same orbital from electron momentum spectroscopy (EMS). The present study reveals information on performance of (a) the density functional methods, (b) Gaussian and Slater basis sets, (c) combinations of the density functional methods and basis sets, that is, the models, (d) orbital momentum distributions, rather than a group of specific molecular properties and (e) the entire region of chemical significance of the orbital. It is found that discrepancies of this orbital between the measured and the calculated occur in the small momentum region (i.e. large r region). In general, Slater basis sets achieve better overall performance than the Gaussian basis sets. Performance of the Gaussian basis sets varies noticeably when combining with different Vxc functionals, but Dunning's augcc-pVTZ basis set achieves the best performance for the momentum distributions of this orbital. The overall performance of the B3LYP and BP86 models is similar to newer models such as X3LYP and SAOP. The present study also demonstrates that the combinations of the density functional methods and the basis sets indeed make a difference in the quality of the

Appropriate criteria set for personnel promotion across organizational levels using analytic hierarchy process (AHP

Directory of Open Access Journals (Sweden)

Charles Noven Castillo

2017-01-01

Full Text Available Currently, there has been limited established specific set of criteria for personnel promotion to each level of the organization. This study is conducted in order to develop a personnel promotion strategy by identifying specific sets of criteria for each level of the organization. The complexity of identifying the criteria set along with the subjectivity of these criteria require the use of multi-criteria decision-making approach particularly the analytic hierarchy process (AHP. Results show different sets of criteria for each management level which are consistent with several frameworks in literature. These criteria sets would help avoid mismatch of employee skills and competencies and their job, and at the same time eliminate the issues in personnel promotion such as favouritism, glass ceiling, and gender and physical attractiveness preference. This work also shows that personality and traits, job satisfaction and experience and skills are more critical rather than social capital across different organizational levels. The contribution of this work is in identifying relevant criteria in developing a personnel promotion strategy across organizational levels.

Level-set techniques for facies identification in reservoir modeling

Science.gov (United States)

Iglesias, Marco A.; McLaughlin, Dennis

2011-03-01

In this paper we investigate the application of level-set techniques for facies identification in reservoir models. The identification of facies is a geometrical inverse ill-posed problem that we formulate in terms of shape optimization. The goal is to find a region (a geologic facies) that minimizes the misfit between predicted and measured data from an oil-water reservoir. In order to address the shape optimization problem, we present a novel application of the level-set iterative framework developed by Burger in (2002 Interfaces Free Bound. 5 301-29 2004 Inverse Problems 20 259-82) for inverse obstacle problems. The optimization is constrained by (the reservoir model) a nonlinear large-scale system of PDEs that describes the reservoir dynamics. We reformulate this reservoir model in a weak (integral) form whose shape derivative can be formally computed from standard results of shape calculus. At each iteration of the scheme, the current estimate of the shape derivative is utilized to define a velocity in the level-set equation. The proper selection of this velocity ensures that the new shape decreases the cost functional. We present results of facies identification where the velocity is computed with the gradient-based (GB) approach of Burger (2002) and the Levenberg-Marquardt (LM) technique of Burger (2004). While an adjoint formulation allows the straightforward application of the GB approach, the LM technique requires the computation of the large-scale Karush-Kuhn-Tucker system that arises at each iteration of the scheme. We efficiently solve this system by means of the representer method. We present some synthetic experiments to show and compare the capabilities and limitations of the proposed implementations of level-set techniques for the identification of geologic facies.

Level-set techniques for facies identification in reservoir modeling

International Nuclear Information System (INIS)

Iglesias, Marco A; McLaughlin, Dennis

2011-01-01

In this paper we investigate the application of level-set techniques for facies identification in reservoir models. The identification of facies is a geometrical inverse ill-posed problem that we formulate in terms of shape optimization. The goal is to find a region (a geologic facies) that minimizes the misfit between predicted and measured data from an oil–water reservoir. In order to address the shape optimization problem, we present a novel application of the level-set iterative framework developed by Burger in (2002 Interfaces Free Bound. 5 301–29; 2004 Inverse Problems 20 259–82) for inverse obstacle problems. The optimization is constrained by (the reservoir model) a nonlinear large-scale system of PDEs that describes the reservoir dynamics. We reformulate this reservoir model in a weak (integral) form whose shape derivative can be formally computed from standard results of shape calculus. At each iteration of the scheme, the current estimate of the shape derivative is utilized to define a velocity in the level-set equation. The proper selection of this velocity ensures that the new shape decreases the cost functional. We present results of facies identification where the velocity is computed with the gradient-based (GB) approach of Burger (2002) and the Levenberg–Marquardt (LM) technique of Burger (2004). While an adjoint formulation allows the straightforward application of the GB approach, the LM technique requires the computation of the large-scale Karush–Kuhn–Tucker system that arises at each iteration of the scheme. We efficiently solve this system by means of the representer method. We present some synthetic experiments to show and compare the capabilities and limitations of the proposed implementations of level-set techniques for the identification of geologic facies

Ultimate Limit State Model Basis for Assessment of Offshore Wind Energy Converters

DEFF Research Database (Denmark)

Thöns, Sebastian; Faber, M. H.; Rücker, W.

2012-01-01

then in combina-tion with the ultimate limit state requirements leads to the specific constitutive relations. As a result finite element models based on shell elements incorporating a structural and a loading model are introduced and described in detail. Applying these models the ultimate capacity of the support...... on the basis of literature review and measurement data from a prototype Multibrid M5000 support structure. In combination with the developed structural and loading models, sensitivity analyses in regard to the responses are peiformed to enhance the understanding and to refine the developed models. To this end...... variables on the responses including nonlinearity the refinement of the model is performed on a quantitative basis....

Solar Power Tower Design Basis Document, Revision 0

Energy Technology Data Exchange (ETDEWEB)

ZAVOICO,ALEXIS B.

2001-07-01

This report contains the design basis for a generic molten-salt solar power tower. A solar power tower uses a field of tracking mirrors (heliostats) that redirect sunlight on to a centrally located receiver mounted on top a tower, which absorbs the concentrated sunlight. Molten nitrate salt, pumped from a tank at ground level, absorbs the sunlight, heating it up to 565 C. The heated salt flows back to ground level into another tank where it is stored, then pumped through a steam generator to produce steam and make electricity. This report establishes a set of criteria upon which the next generation of solar power towers will be designed. The report contains detailed criteria for each of the major systems: Collector System, Receiver System, Thermal Storage System, Steam Generator System, Master Control System, and Electric Heat Tracing System. The Electric Power Generation System and Balance of Plant discussions are limited to interface requirements. This design basis builds on the extensive experience gained from the Solar Two project and includes potential design innovations that will improve reliability and lower technical risk. This design basis document is a living document and contains several areas that require trade-studies and design analysis to fully complete the design basis. Project- and site-specific conditions and requirements will also resolve open To Be Determined issues.

A systematic review of portable electronic technology for health education in resource-limited settings.

Science.gov (United States)

McHenry, Megan S; Fischer, Lydia J; Chun, Yeona; Vreeman, Rachel C

2017-08-01

The objective of this study is to conduct a systematic review of the literature of how portable electronic technologies with offline functionality are perceived and used to provide health education in resource-limited settings. Three reviewers evaluated articles and performed a bibliography search to identify studies describing health education delivered by portable electronic device with offline functionality in low- or middle-income countries. Data extracted included: study population; study design and type of analysis; type of technology used; method of use; setting of technology use; impact on caregivers, patients, or overall health outcomes; and reported limitations. Searches yielded 5514 unique titles. Out of 75 critically reviewed full-text articles, 10 met inclusion criteria. Study locations included Botswana, Peru, Kenya, Thailand, Nigeria, India, Ghana, and Tanzania. Topics addressed included: development of healthcare worker training modules, clinical decision support tools, patient education tools, perceptions and usability of portable electronic technology, and comparisons of technologies and/or mobile applications. Studies primarily looked at the assessment of developed educational modules on trainee health knowledge, perceptions and usability of technology, and comparisons of technologies. Overall, studies reported positive results for portable electronic device-based health education, frequently reporting increased provider/patient knowledge, improved patient outcomes in both quality of care and management, increased provider comfort level with technology, and an environment characterized by increased levels of technology-based, informal learning situations. Negative assessments included high investment costs, lack of technical support, and fear of device theft. While the research is limited, portable electronic educational resources present promising avenues to increase access to effective health education in resource-limited settings, contingent

Spectral properties of minimal-basis-set orbitals: Implications for molecular electronic continuum states

Science.gov (United States)

Langhoff, P. W.; Winstead, C. L.

Early studies of the electronically excited states of molecules by John A. Pople and coworkers employing ab initio single-excitation configuration interaction (SECI) calculations helped to simulate related applications of these methods to the partial-channel photoionization cross sections of polyatomic molecules. The Gaussian representations of molecular orbitals adopted by Pople and coworkers can describe SECI continuum states when sufficiently large basis sets are employed. Minimal-basis virtual Fock orbitals stabilized in the continuous portions of such SECI spectra are generally associated with strong photoionization resonances. The spectral attributes of these resonance orbitals are illustrated here by revisiting previously reported experimental and theoretical studies of molecular formaldehyde (H2CO) in combination with recently calculated continuum orbital amplitudes.

Current strategies for improving access and adherence to antiretroviral therapies in resource-limited settings

Directory of Open Access Journals (Sweden)

Scanlon ML

2013-01-01

Full Text Available Michael L Scanlon,1,2 Rachel C Vreeman1,21Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA; 2USAID, Academic Model Providing Access to Healthcare (AMPATH Partnership, Eldoret, KenyaAbstract: The rollout of antiretroviral therapy (ART significantly reduced human immunodeficiency virus (HIV-related morbidity and mortality, but good clinical outcomes depend on access and adherence to treatment. In resource-limited settings, where over 90% of the world’s HIV-infected population resides, data on barriers to treatment are emerging that contribute to low rates of uptake in HIV testing, linkage to and retention in HIV care systems, and suboptimal adherence rates to therapy. A review of the literature reveals limited evidence to inform strategies to improve access and adherence with the majority of studies from sub-Saharan Africa. Data from observational studies and randomized controlled trials support home-based, mobile and antenatal care HIV testing, task-shifting from doctor-based to nurse-based and lower level provider care, and adherence support through education, counseling and mobile phone messaging services. Strategies with more limited evidence include targeted HIV testing for couples and family members of ART patients, decentralization of HIV care, including through home- and community-based ART programs, and adherence promotion through peer health workers, treatment supporters, and directly observed therapy. There is little evidence for improving access and adherence among vulnerable groups such as women, children and adolescents, and other high-risk populations and for addressing major barriers. Overall, studies are few in number and suffer from methodological issues. Recommendations for further research include health information technology, social-level factors like HIV stigma, and new research directions in cost-effectiveness, operations, and implementation. Findings from this review make a

Basis set expansion for inverse problems in plasma diagnostic analysis

Energy Technology Data Exchange (ETDEWEB)

Jones, B.; Ruiz, C. L. [Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185 (United States)

2013-07-15

A basis set expansion method [V. Dribinski, A. Ossadtchi, V. A. Mandelshtam, and H. Reisler, Rev. Sci. Instrum. 73, 2634 (2002)] is applied to recover physical information about plasma radiation sources from instrument data, which has been forward transformed due to the nature of the measurement technique. This method provides a general approach for inverse problems, and we discuss two specific examples relevant to diagnosing fast z pinches on the 20–25 MA Z machine [M. E. Savage, L. F. Bennett, D. E. Bliss, W. T. Clark, R. S. Coats, J. M. Elizondo, K. R. LeChien, H. C. Harjes, J. M. Lehr, J. E. Maenchen, D. H. McDaniel, M. F. Pasik, T. D. Pointon, A. C. Owen, D. B. Seidel, D. L. Smith, B. S. Stoltzfus, K. W. Struve, W. A. Stygar, L. K. Warne, J. R. Woodworth, C. W. Mendel, K. R. Prestwich, R. W. Shoup, D. L. Johnson, J. P. Corley, K. C. Hodge, T. C. Wagoner, and P. E. Wakeland, in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, 2007), p. 979]. First, Abel inversion of time-gated, self-emission x-ray images from a wire array implosion is studied. Second, we present an approach for unfolding neutron time-of-flight measurements from a deuterium gas puff z pinch to recover information about emission time history and energy distribution. Through these examples, we discuss how noise in the measured data limits the practical resolution of the inversion, and how the method handles discontinuities in the source function and artifacts in the projected image. We add to the method a propagation of errors calculation for estimating uncertainties in the inverted solution.

Defining the anesthesia gap for reproductive health procedures in resource-limited settings.

Science.gov (United States)

Anderson, R Eleanor; Ahn, Roy; Nelson, Brett D; Chavez, Jean; de Redon, Emily; Burke, Thomas

2014-12-01

In resource-limited settings, severe shortages of anesthetists and anesthesiologists lead to surgical delays that increase maternal and neonatal mortality and morbidity. To more clearly understand the individual components of the anesthesia gap pertaining to reproductive health surgeries and procedures in resource-limited settings. Medline, the Cochrane Library, CINAHL, Embase, and POPLINE were systematically searched for reports published before December 31, 2013. Search terms were related to obstetric surgery, resource-limited settings, and anesthesia. Studies that addressed the use of anesthesia in reproductive procedures in resource-limited settings were included. Reviewers independently evaluated the full text of identified studies, extracted information related to study objectives and conclusions, and identified the anesthesia gap. Overall, 14 publications met the inclusion criteria. A significant lack of infrastructure, equipment and supplies, and trained personnel were identified as key factors responsible for a lack of anesthesia services. A shortage of trained anesthesia providers, equipment, supplies, medications, and infrastructure, along with limitations in transportation in resource-limited settings have produced a wide gap between available anesthesia services and the demand for them for reproductive health surgeries and procedures. Safe, affordable, and scalable solutions to address the anesthesia gap are urgently needed. Copyright © 2014 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

Volume Sculpting Using the Level-Set Method

DEFF Research Database (Denmark)

Bærentzen, Jakob Andreas; Christensen, Niels Jørgen

2002-01-01

In this paper, we propose the use of the Level--Set Method as the underlying technology of a volume sculpting system. The main motivation is that this leads to a very generic technique for deformation of volumetric solids. In addition, our method preserves a distance field volume representation....... A scaling window is used to adapt the Level--Set Method to local deformations and to allow the user to control the intensity of the tool. Level--Set based tools have been implemented in an interactive sculpting system, and we show sculptures created using the system....

Adaptive local basis set for Kohn–Sham density functional theory in a discontinuous Galerkin framework II: Force, vibration, and molecular dynamics calculations

Energy Technology Data Exchange (ETDEWEB)

Zhang, Gaigong [Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Lin, Lin, E-mail: linlin@math.berkeley.edu [Department of Mathematics, University of California, Berkeley, Berkeley, CA 94720 (United States); Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Hu, Wei, E-mail: whu@lbl.gov [Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Yang, Chao, E-mail: cyang@lbl.gov [Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Pask, John E., E-mail: pask1@llnl.gov [Physics Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)

2017-04-15

Recently, we have proposed the adaptive local basis set for electronic structure calculations based on Kohn–Sham density functional theory in a pseudopotential framework. The adaptive local basis set is efficient and systematically improvable for total energy calculations. In this paper, we present the calculation of atomic forces, which can be used for a range of applications such as geometry optimization and molecular dynamics simulation. We demonstrate that, under mild assumptions, the computation of atomic forces can scale nearly linearly with the number of atoms in the system using the adaptive local basis set. We quantify the accuracy of the Hellmann–Feynman forces for a range of physical systems, benchmarked against converged planewave calculations, and find that the adaptive local basis set is efficient for both force and energy calculations, requiring at most a few tens of basis functions per atom to attain accuracies required in practice. Since the adaptive local basis set has implicit dependence on atomic positions, Pulay forces are in general nonzero. However, we find that the Pulay force is numerically small and systematically decreasing with increasing basis completeness, so that the Hellmann–Feynman force is sufficient for basis sizes of a few tens of basis functions per atom. We verify the accuracy of the computed forces in static calculations of quasi-1D and 3D disordered Si systems, vibration calculation of a quasi-1D Si system, and molecular dynamics calculations of H{sub 2} and liquid Al–Si alloy systems, where we show systematic convergence to benchmark planewave results and results from the literature.

A geometrical correction for the inter- and intra-molecular basis set superposition error in Hartree-Fock and density functional theory calculations for large systems

Science.gov (United States)

Kruse, Holger; Grimme, Stefan

2012-04-01

A semi-empirical counterpoise-type correction for basis set superposition error (BSSE) in molecular systems is presented. An atom pair-wise potential corrects for the inter- and intra-molecular BSSE in supermolecular Hartree-Fock (HF) or density functional theory (DFT) calculations. This geometrical counterpoise (gCP) denoted scheme depends only on the molecular geometry, i.e., no input from the electronic wave-function is required and hence is applicable to molecules with ten thousands of atoms. The four necessary parameters have been determined by a fit to standard Boys and Bernadi counterpoise corrections for Hobza's S66×8 set of non-covalently bound complexes (528 data points). The method's target are small basis sets (e.g., minimal, split-valence, 6-31G*), but reliable results are also obtained for larger triple-ζ sets. The intermolecular BSSE is calculated by gCP within a typical error of 10%-30% that proves sufficient in many practical applications. The approach is suggested as a quantitative correction in production work and can also be routinely applied to estimate the magnitude of the BSSE beforehand. The applicability for biomolecules as the primary target is tested for the crambin protein, where gCP removes intramolecular BSSE effectively and yields conformational energies comparable to def2-TZVP basis results. Good mutual agreement is also found with Jensen's ACP(4) scheme, estimating the intramolecular BSSE in the phenylalanine-glycine-phenylalanine tripeptide, for which also a relaxed rotational energy profile is presented. A variety of minimal and double-ζ basis sets combined with gCP and the dispersion corrections DFT-D3 and DFT-NL are successfully benchmarked on the S22 and S66 sets of non-covalent interactions. Outstanding performance with a mean absolute deviation (MAD) of 0.51 kcal/mol (0.38 kcal/mol after D3-refit) is obtained at the gCP-corrected HF-D3/(minimal basis) level for the S66 benchmark. The gCP-corrected B3LYP-D3/6-31G* model

A geometrical correction for the inter- and intra-molecular basis set superposition error in Hartree-Fock and density functional theory calculations for large systems.

Science.gov (United States)

Kruse, Holger; Grimme, Stefan

2012-04-21

A semi-empirical counterpoise-type correction for basis set superposition error (BSSE) in molecular systems is presented. An atom pair-wise potential corrects for the inter- and intra-molecular BSSE in supermolecular Hartree-Fock (HF) or density functional theory (DFT) calculations. This geometrical counterpoise (gCP) denoted scheme depends only on the molecular geometry, i.e., no input from the electronic wave-function is required and hence is applicable to molecules with ten thousands of atoms. The four necessary parameters have been determined by a fit to standard Boys and Bernadi counterpoise corrections for Hobza's S66×8 set of non-covalently bound complexes (528 data points). The method's target are small basis sets (e.g., minimal, split-valence, 6-31G*), but reliable results are also obtained for larger triple-ζ sets. The intermolecular BSSE is calculated by gCP within a typical error of 10%-30% that proves sufficient in many practical applications. The approach is suggested as a quantitative correction in production work and can also be routinely applied to estimate the magnitude of the BSSE beforehand. The applicability for biomolecules as the primary target is tested for the crambin protein, where gCP removes intramolecular BSSE effectively and yields conformational energies comparable to def2-TZVP basis results. Good mutual agreement is also found with Jensen's ACP(4) scheme, estimating the intramolecular BSSE in the phenylalanine-glycine-phenylalanine tripeptide, for which also a relaxed rotational energy profile is presented. A variety of minimal and double-ζ basis sets combined with gCP and the dispersion corrections DFT-D3 and DFT-NL are successfully benchmarked on the S22 and S66 sets of non-covalent interactions. Outstanding performance with a mean absolute deviation (MAD) of 0.51 kcal/mol (0.38 kcal/mol after D3-refit) is obtained at the gCP-corrected HF-D3/(minimal basis) level for the S66 benchmark. The gCP-corrected B3LYP-D3/6-31G* model

Establishing Medical Schools in Limited Resource Settings | Girma ...

African Journals Online (AJOL)

Establishing Medical Schools in Limited Resource Settings. ... These countries face challenges related to the rapid scale up which is mostly done without proper strategic planning, without the basic elements of infrastructure development, educational as well as academic and administrative human resources. Medical ...

Fast Sparse Level Sets on Graphics Hardware

NARCIS (Netherlands)

Jalba, Andrei C.; Laan, Wladimir J. van der; Roerdink, Jos B.T.M.

The level-set method is one of the most popular techniques for capturing and tracking deformable interfaces. Although level sets have demonstrated great potential in visualization and computer graphics applications, such as surface editing and physically based modeling, their use for interactive

Multiple-level stakeholder engagement in malaria clinical trials: addressing the challenges of conducting clinical research in resource-limited settings.

Science.gov (United States)

Mtove, George; Kimani, Joshua; Kisinza, William; Makenga, Geofrey; Mangesho, Peter; Duparc, Stephan; Nakalembe, Miriam; Phiri, Kamija S; Orrico, Russell; Rojo, Ricardo; Vandenbroucke, Pol

2018-03-22

Multinational clinical trials are logistically complex and require close coordination between various stakeholders. They must comply with global clinical standards and are accountable to multiple regulatory and ethical bodies. In resource-limited settings, it is challenging to understand how to apply global clinical standards to international, national, and local factors in clinical trials, making multiple-level stakeholder engagement an important element in the successful conduct of these clinical trials. During the planning and implementation of a large multinational clinical trial for intermittent preventive treatment of malaria in pregnancy in resource-limited areas of sub-Saharan Africa, we encountered numerous challenges, which required implementation of a range of engagement measures to ensure compliance with global clinical and regulatory standards. These challenges included coordination with ongoing global malaria efforts, heterogeneity in national regulatory structures, sub-optimal healthcare infrastructure, local practices and beliefs, and perspectives that view healthcare providers with undue trust or suspicion. In addition to engagement with international bodies, such as the World Health Organization, the Malaria in Pregnancy Consortium, the Steve Biko Centre for Bioethics, and the London School of Hygiene and Tropical Medicine, in order to address the challenges just described, Pfizer Inc. and Medicines for Malaria Venture (the "Sponsoring Entities" for these studies) and investigators liaised with national- and district-level stakeholders such as health ministers and regional/local community health workers. Community engagement measures undertaken by investigators included local meetings with community leaders to explain the research aims and answer questions and concerns voiced by the community. The investigators also engaged with family members of prospective trial participants in order to be sensitive to local practices and beliefs. Engagement

A new level set model for multimaterial flows

Energy Technology Data Exchange (ETDEWEB)

Starinshak, David P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Karni, Smadar [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Mathematics; Roe, Philip L. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of AerospaceEngineering

2014-01-08

We present a new level set model for representing multimaterial flows in multiple space dimensions. Instead of associating a level set function with a specific fluid material, the function is associated with a pair of materials and the interface that separates them. A voting algorithm collects sign information from all level sets and determines material designations. M(M ₋1)/2 level set functions might be needed to represent a general M-material configuration; problems of practical interest use far fewer functions, since not all pairs of materials share an interface. The new model is less prone to producing indeterminate material states, i.e. regions claimed by more than one material (overlaps) or no material at all (vacuums). It outperforms existing material-based level set models without the need for reinitialization schemes, thereby avoiding additional computational costs and preventing excessive numerical diffusion.

An examination of intrinsic errors in electronic structure methods using the Environmental Molecular Sciences Laboratory computational results database and the Gaussian-2 set

International Nuclear Information System (INIS)

Feller, D.; Peterson, K.A.

1998-01-01

The Gaussian-2 (G2) collection of atoms and molecules has been studied with Hartree endash Fock and correlated levels of theory, ranging from second-order perturbation theory to coupled cluster theory with noniterative inclusion of triple excitations. By exploiting the systematic convergence properties of the correlation consistent family of basis sets, complete basis set limits were estimated for a large number of the G2 energetic properties. Deviations with respect to experimentally derived energy differences corresponding to rigid molecules were obtained for 15 basis set/method combinations, as well as the estimated complete basis set limit. The latter values are necessary for establishing the intrinsic error for each method. In order to perform this analysis, the information generated in the present study was combined with the results of many previous benchmark studies in an electronic database, where it is available for use by other software tools. Such tools can assist users of electronic structure codes in making appropriate basis set and method choices that will increase the likelihood of achieving their accuracy goals without wasteful expenditures of computer resources. copyright 1998 American Institute of Physics

42 CFR 415.170 - Conditions for payment on a fee schedule basis for physician services in a teaching setting.

Science.gov (United States)

2010-10-01

... physician services in a teaching setting. 415.170 Section 415.170 Public Health CENTERS FOR MEDICARE... BY PHYSICIANS IN PROVIDERS, SUPERVISING PHYSICIANS IN TEACHING SETTINGS, AND RESIDENTS IN CERTAIN SETTINGS Physician Services in Teaching Settings § 415.170 Conditions for payment on a fee schedule basis...

Need for reaction coordinates to ensure a complete basis set in an adiabatic representation of ion-atom collisions

Science.gov (United States)

Rabli, Djamal; McCarroll, Ronald

2018-02-01

This review surveys the different theoretical approaches, used to describe inelastic and rearrangement processes in collisions involving atoms and ions. For a range of energies from a few meV up to about 1 keV, the adiabatic representation is expected to be valid and under these conditions, inelastic and rearrangement processes take place via a network of avoided crossings of the potential energy curves of the collision system. In general, such avoided crossings are finite in number. The non-adiabatic coupling, due to the breakdown of the Born-Oppenheimer separation of the electronic and nuclear variables, depends on the ratio of the electron mass to the nuclear mass terms in the total Hamiltonian. By limiting terms in the total Hamiltonian correct to first order in the electron to nuclear mass ratio, a system of reaction coordinates is found which allows for a correct description of both inelastic channels. The connection between the use of reaction coordinates in the quantum description and the electron translation factors of the impact parameter approach is established. A major result is that only when reaction coordinates are used, is it possible to introduce the notion of a minimal basis set. Such a set must include all avoided crossings including both radial coupling and long range Coriolis coupling. But, only when reactive coordinates are used, can such a basis set be considered as complete. In particular when the centre of nuclear mass is used as centre of coordinates, rather than the correct reaction coordinates, it is shown that erroneous results are obtained. A few results to illustrate this important point are presented: one concerning a simple two-state Landau-Zener type avoided crossing, the other concerning a network of multiple crossings in a typical electron capture process involving a highly charged ion with a neutral atom.

Kohn-Sham potentials from electron densities using a matrix representation within finite atomic orbital basis sets

Science.gov (United States)

Zhang, Xing; Carter, Emily A.

2018-01-01

We revisit the static response function-based Kohn-Sham (KS) inversion procedure for determining the KS effective potential that corresponds to a given target electron density within finite atomic orbital basis sets. Instead of expanding the potential in an auxiliary basis set, we directly update the potential in its matrix representation. Through numerical examples, we show that the reconstructed density rapidly converges to the target density. Preliminary results are presented to illustrate the possibility of obtaining a local potential in real space from the optimized potential in its matrix representation. We have further applied this matrix-based KS inversion approach to density functional embedding theory. A proof-of-concept study of a solvated proton transfer reaction demonstrates the method's promise.

Formulation of improved basis sets for the study of polymer dynamics through diffusion theory methods.

Science.gov (United States)

Gaspari, Roberto; Rapallo, Arnaldo

2008-06-28

In this work a new method is proposed for the choice of basis functions in diffusion theory (DT) calculations. This method, named hybrid basis approach (HBA), combines the two previously adopted long time sorting procedure (LTSP) and maximum correlation approximation (MCA) techniques; the first emphasizing contributions from the long time dynamics, the latter being based on the local correlations along the chain. In order to fulfill this task, the HBA procedure employs a first order basis set corresponding to a high order MCA one and generates upper order approximations according to LTSP. A test of the method is made first on a melt of cis-1,4-polyisoprene decamers where HBA and LTSP are compared in terms of efficiency. Both convergence properties and numerical stability are improved by the use of the HBA basis set whose performance is evaluated on local dynamics, by computing the correlation times of selected bond vectors along the chain, and on global ones, through the eigenvalues of the diffusion operator L. Further use of the DT with a HBA basis set has been made on a 71-mer of syndiotactic trans-1,2-polypentadiene in toluene solution, whose dynamical properties have been computed with a high order calculation and compared to the "numerical experiment" provided by the molecular dynamics (MD) simulation in explicit solvent. The necessary equilibrium averages have been obtained by a vacuum trajectory of the chain where solvent effects on conformational properties have been reproduced with a proper screening of the nonbonded interactions, corresponding to a definite value of the mean radius of gyration of the polymer in vacuum. Results show a very good agreement between DT calculations and the MD numerical experiment. This suggests a further use of DT methods with the necessary input quantities obtained by the only knowledge of some experimental values, i.e., the mean radius of gyration of the chain and the viscosity of the solution, and by a suitable vacuum

Pseudo-atomic orbitals as basis sets for the O(N) DFT code CONQUEST

Energy Technology Data Exchange (ETDEWEB)

Torralba, A S; Brazdova, V; Gillan, M J; Bowler, D R [Materials Simulation Laboratory, UCL, Gower Street, London WC1E 6BT (United Kingdom); Todorovic, M; Miyazaki, T [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Choudhury, R [London Centre for Nanotechnology, UCL, 17-19 Gordon Street, London WC1H 0AH (United Kingdom)], E-mail: david.bowler@ucl.ac.uk

2008-07-23

Various aspects of the implementation of pseudo-atomic orbitals (PAOs) as basis functions for the linear scaling CONQUEST code are presented. Preliminary results for the assignment of a large set of PAOs to a smaller space of support functions are encouraging, and an important related proof on the necessary symmetry of the support functions is shown. Details of the generation and integration schemes for the PAOs are also given.

Conceptual basis for evaluating risk from low-level radiation exposure

International Nuclear Information System (INIS)

Bond, V.P.

1981-01-01

Serious or lethal injuries that may result from the exposure of animals or human beings to ionizing radiations can be divided into two distinctly different categories, on the basis of whether the injury results only from failure of an entire vital organ, or stems from impairment of the function of a single cell. These two categories of injury are termed here organ effects, normally induced by non-stochastic processes, and single cell effects, normally induced by stochastic processes. This presentation is limited to low-level radiation exposure (LLR) since: (1) only with single hit kinetics does the average number of cell doses per cell in the exposed population essentially equal the number of cells dosed; (2) in excluding multihit all-or-none effects, the functions developed are essentially independent of the time rate at which the (instantaneously deposited) cell doses are laid down, and of considerations of repair of sub-effect injury; and (3) it makes little or no difference with LLR if the incidence of single cell effects is expressed in terms of exposed or surviving cells

Basis set expansion for inverse problems in plasma diagnostic analysis

Science.gov (United States)

Jones, B.; Ruiz, C. L.

2013-07-01

A basis set expansion method [V. Dribinski, A. Ossadtchi, V. A. Mandelshtam, and H. Reisler, Rev. Sci. Instrum. 73, 2634 (2002)], 10.1063/1.1482156 is applied to recover physical information about plasma radiation sources from instrument data, which has been forward transformed due to the nature of the measurement technique. This method provides a general approach for inverse problems, and we discuss two specific examples relevant to diagnosing fast z pinches on the 20-25 MA Z machine [M. E. Savage, L. F. Bennett, D. E. Bliss, W. T. Clark, R. S. Coats, J. M. Elizondo, K. R. LeChien, H. C. Harjes, J. M. Lehr, J. E. Maenchen, D. H. McDaniel, M. F. Pasik, T. D. Pointon, A. C. Owen, D. B. Seidel, D. L. Smith, B. S. Stoltzfus, K. W. Struve, W. A. Stygar, L. K. Warne, J. R. Woodworth, C. W. Mendel, K. R. Prestwich, R. W. Shoup, D. L. Johnson, J. P. Corley, K. C. Hodge, T. C. Wagoner, and P. E. Wakeland, in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, 2007), p. 979]. First, Abel inversion of time-gated, self-emission x-ray images from a wire array implosion is studied. Second, we present an approach for unfolding neutron time-of-flight measurements from a deuterium gas puff z pinch to recover information about emission time history and energy distribution. Through these examples, we discuss how noise in the measured data limits the practical resolution of the inversion, and how the method handles discontinuities in the source function and artifacts in the projected image. We add to the method a propagation of errors calculation for estimating uncertainties in the inverted solution.

Can Oxygen Set Thermal Limits in an Insect and Drive Gigantism?

Science.gov (United States)

Verberk, Wilco C. E. P.; Bilton, David T.

2011-01-01

Background Thermal limits may arise through a mismatch between oxygen supply and demand in a range of animal taxa. Whilst this oxygen limitation hypothesis is supported by data from a range of marine fish and invertebrates, its generality remains contentious. In particular, it is unclear whether oxygen limitation determines thermal extremes in tracheated arthropods, where oxygen limitation may be unlikely due to the efficiency and plasticity of tracheal systems in supplying oxygen directly to metabolically active tissues. Although terrestrial taxa with open tracheal systems may not be prone to oxygen limitation, species may be affected during other life-history stages, particularly if these rely on diffusion into closed tracheal systems. Furthermore, a central role for oxygen limitation in insects is envisaged within a parallel line of research focussing on insect gigantism in the late Palaeozoic. Methodology/Principal Findings Here we examine thermal maxima in the aquatic life stages of an insect at normoxia, hypoxia (14 kPa) and hyperoxia (36 kPa). We demonstrate that upper thermal limits do indeed respond to external oxygen supply in the aquatic life stages of the stonefly Dinocras cephalotes, suggesting that the critical thermal limits of such aquatic larvae are set by oxygen limitation. This could result from impeded oxygen delivery, or limited oxygen regulatory capacity, both of which have implications for our understanding of the limits to insect body size and how these are influenced by atmospheric oxygen levels. Conclusions/Significance These findings extend the generality of the hypothesis of oxygen limitation of thermal tolerance, suggest that oxygen constraints on body size may be stronger in aquatic environments, and that oxygen toxicity may have actively selected for gigantism in the aquatic stages of Carboniferous arthropods. PMID:21818347

Can oxygen set thermal limits in an insect and drive gigantism?

Directory of Open Access Journals (Sweden)

Wilco C E P Verberk

Full Text Available BACKGROUND: Thermal limits may arise through a mismatch between oxygen supply and demand in a range of animal taxa. Whilst this oxygen limitation hypothesis is supported by data from a range of marine fish and invertebrates, its generality remains contentious. In particular, it is unclear whether oxygen limitation determines thermal extremes in tracheated arthropods, where oxygen limitation may be unlikely due to the efficiency and plasticity of tracheal systems in supplying oxygen directly to metabolically active tissues. Although terrestrial taxa with open tracheal systems may not be prone to oxygen limitation, species may be affected during other life-history stages, particularly if these rely on diffusion into closed tracheal systems. Furthermore, a central role for oxygen limitation in insects is envisaged within a parallel line of research focussing on insect gigantism in the late Palaeozoic. METHODOLOGY/PRINCIPAL FINDINGS: Here we examine thermal maxima in the aquatic life stages of an insect at normoxia, hypoxia (14 kPa and hyperoxia (36 kPa. We demonstrate that upper thermal limits do indeed respond to external oxygen supply in the aquatic life stages of the stonefly Dinocras cephalotes, suggesting that the critical thermal limits of such aquatic larvae are set by oxygen limitation. This could result from impeded oxygen delivery, or limited oxygen regulatory capacity, both of which have implications for our understanding of the limits to insect body size and how these are influenced by atmospheric oxygen levels. CONCLUSIONS/SIGNIFICANCE: These findings extend the generality of the hypothesis of oxygen limitation of thermal tolerance, suggest that oxygen constraints on body size may be stronger in aquatic environments, and that oxygen toxicity may have actively selected for gigantism in the aquatic stages of Carboniferous arthropods.

New STO(II-3Gmag family basis sets for the calculations of the molecules magnetic properties

Directory of Open Access Journals (Sweden)

Karina Kapusta

2015-10-01

Full Text Available An efficient approach for construction of physically justified STO(II-3Gmag family basis sets for calculation of molecules magnetic properties has been proposed. The procedure of construction based upon the taken into account the second order of perturbation theory in the magnetic field case. Analytical form of correction functions has been obtained using the closed representation of the Green functions by the solution of nonhomogeneous Schrödinger equation for the model problem of "one-electron atom in the external uniform magnetic field". Their performance has been evaluated for the DFT level calculations carried out with a number of functionals. The test calculations of magnetic susceptibility and 1H nuclear magnetic shielding tensors demonstrated a good agreement of the calculated values with the experimental data.

The limitations of using randomised controlled trials as a basis for developing treatment guidelines.

Science.gov (United States)

Mulder, Roger; Singh, Ajeet B; Hamilton, Amber; Das, Pritha; Outhred, Tim; Morris, Grace; Bassett, Darryl; Baune, Bernhard T; Berk, Michael; Boyce, Philip; Lyndon, Bill; Parker, Gordon; Malhi, Gin S

2018-02-01

Randomised controlled trials (RCTs) are considered the 'gold standard' by which novel psychotropic medications and psychological interventions are evaluated and consequently adopted into widespread clinical practice. However, there are some limitations to using RCTs as the basis for developing treatment guidelines. While RCTs allow researchers to determine whether a given medication or intervention is effective in a specific patient sample, for practicing clinicians it is more important to know whether it will work for their particular patient in their particular setting. This information cannot be garnered from an RCT. These inherent limitations are exacerbated by biases in design, recruitment, sample populations and data analysis that are inevitable in real-world studies. While trial registration and CONSORT have been implemented to correct and improve these issues, it is worrying that many trials fail to achieve such standards and yet their findings are used to inform clinical decision making. This perspective piece questions the assumptions of RCTs and highlights the widespread distortion of findings that currently undermine the credibility of this powerful design. It is recommended that the clinical guidelines include advice as to what should be considered good and relevant evidence and that external bodies continue to monitor RCTs to ensure that the outcomes published indeed reflect reality. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Exploring the level sets of quantum control landscapes

International Nuclear Information System (INIS)

Rothman, Adam; Ho, Tak-San; Rabitz, Herschel

2006-01-01

A quantum control landscape is defined by the value of a physical observable as a functional of the time-dependent control field E(t) for a given quantum-mechanical system. Level sets through this landscape are prescribed by a particular value of the target observable at the final dynamical time T, regardless of the intervening dynamics. We present a technique for exploring a landscape level set, where a scalar variable s is introduced to characterize trajectories along these level sets. The control fields E(s,t) accomplishing this exploration (i.e., that produce the same value of the target observable for a given system) are determined by solving a differential equation over s in conjunction with the time-dependent Schroedinger equation. There is full freedom to traverse a level set, and a particular trajectory is realized by making an a priori choice for a continuous function f(s,t) that appears in the differential equation for the control field. The continuous function f(s,t) can assume an arbitrary form, and thus a level set generally contains a family of controls, where each control takes the quantum system to the same final target value, but produces a distinct control mechanism. In addition, although the observable value remains invariant over the level set, other dynamical properties (e.g., the degree of robustness to control noise) are not specifically preserved and can vary greatly. Examples are presented to illustrate the continuous nature of level-set controls and their associated induced dynamical features, including continuously morphing mechanisms for population control in model quantum systems

Upper limit set for level of lightning activity on Titan

Science.gov (United States)

Desch, M. D.; Kaiser, M. L.

1990-01-01

Because optically thick cloud and haze layers prevent lightning detection at optical wavelength on Titan, a search was conducted for lightning-radiated signals (spherics) at radio wavelengths using the planetary radioastronomy instrument aboard Voyager 1. Given the maximum ionosphere density of about 3000/cu cm, lightning spherics should be detectable above an observing frequency of 500 kHz. Since no evidence for spherics is found, an upper limit to the total energy per flash in Titan lightning of about 10 to the 6th J, or about 1000 times weaker than that of typical terrestrial lightning, is inferred.

Symmetry-adapted basis sets automatic generation for problems in chemistry and physics

CERN Document Server

Avery, John Scales; Avery, James Emil

2012-01-01

In theoretical physics, theoretical chemistry and engineering, one often wishes to solve partial differential equations subject to a set of boundary conditions. This gives rise to eigenvalue problems of which some solutions may be very difficult to find. For example, the problem of finding eigenfunctions and eigenvalues for the Hamiltonian of a many-particle system is usually so difficult that it requires approximate methods, the most common of which is expansion of the eigenfunctions in terms of basis functions that obey the boundary conditions of the problem. The computational effort needed

Optimising Mycobacterium tuberculosis detection in resource limited settings.

Science.gov (United States)

Alfred, Nwofor; Lovette, Lawson; Aliyu, Gambo; Olusegun, Obasanya; Meshak, Panwal; Jilang, Tunkat; Iwakun, Mosunmola; Nnamdi, Emenyonu; Olubunmi, Onuoha; Dakum, Patrick; Abimiku, Alash'le

2014-03-03

The light-emitting diode (LED) fluorescence microscopy has made acid-fast bacilli (AFB) detection faster and efficient although its optimal performance in resource-limited settings is still being studied. We assessed the optimal performances of light and fluorescence microscopy in routine conditions of a resource-limited setting and evaluated the digestion time for sputum samples for maximum yield of positive cultures. Cross-sectional study. Facility-based involving samples of routine patients receiving tuberculosis treatment and care from the main tuberculosis case referral centre in northern Nigeria. The study included 450 sputum samples from 150 new patients with clinical diagnosis of pulmonary tuberculosis. The 450 samples were pooled into 150 specimens, examined independently with mercury vapour lamp (FM), LED CysCope (CY) and Primo Star iLED (PiLED) fluorescence microscopies, and with the Ziehl-Neelsen (ZN) microscopy to assess the performance of each technique compared with liquid culture. The cultured specimens were decontaminated with BD Mycoprep (4% NaOH-1% NLAC and 2.9% sodium citrate) for 10, 15 and 20 min before incubation in Mycobacterium growth incubator tube (MGIT) system and growth examined for acid-fast bacilli (AFB). Of the 150 specimens examined by direct microscopy: 44 (29%), 60 (40%), 49 (33%) and 64 (43%) were AFB positive by ZN, FM, CY and iLED microscopy, respectively. Digestion of sputum samples for 10, 15 and 20 min yielded mycobacterial growth in 72 (48%), 81 (54%) and 68 (45%) of the digested samples, respectively, after incubation in the MGIT system. In routine laboratory conditions of a resource-limited setting, our study has demonstrated the superiority of fluorescence microscopy over the conventional ZN technique. Digestion of sputum samples for 15 min yielded more positive cultures.

On the accuracy of density-functional theory exchange-correlation functionals for H bonds in small water clusters: Benchmarks approaching the complete basis set limit

Science.gov (United States)

Santra, Biswajit; Michaelides, Angelos; Scheffler, Matthias

2007-11-01

The ability of several density-functional theory (DFT) exchange-correlation functionals to describe hydrogen bonds in small water clusters (dimer to pentamer) in their global minimum energy structures is evaluated with reference to second order Møller-Plesset perturbation theory (MP2). Errors from basis set incompleteness have been minimized in both the MP2 reference data and the DFT calculations, thus enabling a consistent systematic evaluation of the true performance of the tested functionals. Among all the functionals considered, the hybrid X3LYP and PBE0 functionals offer the best performance and among the nonhybrid generalized gradient approximation functionals, mPWLYP and PBE1W perform best. The popular BLYP and B3LYP functionals consistently underbind and PBE and PW91 display rather variable performance with cluster size.

Experiences from occupational exposure limits set on aerosols containing allergenic proteins

DEFF Research Database (Denmark)

Nielsen, Gunnar; Larsen, Søren; Hansen, Jitka S

2012-01-01

Occupational exposure limits (OELs) together with determined airborne exposures are used in risk assessment based managements of occupational exposures to prevent occupational diseases. In most countries, OELs have only been set for few protein-containing aerosols causing IgE-mediated allergies. ...... is available for setting OELs for proteins and protein-containing aerosols where the critical effect is IgE sensitization and IgE-mediated airway diseases.......Occupational exposure limits (OELs) together with determined airborne exposures are used in risk assessment based managements of occupational exposures to prevent occupational diseases. In most countries, OELs have only been set for few protein-containing aerosols causing IgE-mediated allergies...... for setting OELs. Our aim is to analyse prerequisites for setting OELs for the allergenic protein-containing aerosols. Opposite to the key effect of toxicological reactions, two thresholds, one for the sensitization phase and one for elicitation of IgE-mediated symptoms in sensitized individuals, are used...

Goal oriented Mathematics Survey at Preparatory Level- Revised set ...

African Journals Online (AJOL)

This cross sectional study design on mathematical syllabi at preparatory levels of the high schools was to investigate the efficiency of the subject at preparatory level education serving as a basis for several streams, like Natural science, Technology, Computer Science, Health Science and Agriculture found at tertiary levels.

Therapeutic drug monitoring of nevirapine in resource-limited settings.

NARCIS (Netherlands)

L'homme, R.F.A.; Muro, E.P.; Droste, J.A.H.; Wolters, L.R.; Ewijk-Beneken Kolmer, E.W.J. van; Schimana, W.; Burger, D.M.

2008-01-01

BACKGROUND: We developed a simple and inexpensive thin-layer chromatography (TLC) assay for semiquantitative detection of saliva concentrations of nevirapine in resource-limited settings. The method was validated in an African target population. METHODS: Paired plasma and saliva nevirapine

Tuberculosis diagnosis in resource-limited settings: Clinical use of ...

African Journals Online (AJOL)

EB

GeneXpert in the diagnosis of smear-negative PTB: a case report ... Background: The Xpert MTB/RIF test (GeneXpert) has recently been endorsed for use in resource-limited settings for the ... normochromic anemia (9.2g/dl), hypoalbuminemia.

Advantages and limitations of the SETS method

International Nuclear Information System (INIS)

Mahaffy, J.H.

1983-01-01

The stability-enchancing two-step (SETS) method has been used successfully in the Transient Reactor Analysis Code (TRAC) for several years. The method consists of a basic semi-implicit step combined with a stabilizer step that, taken together, eliminate the material Courant stability limit associated with standard semi-implicit numerical methods. This approach toward stability requires significantly fewer computational operations than a fully implicit method, but currently maintains the first-order accuracy in space and time of its semi-implicit predecessors

On sets of vectors of a finite vector space in which every subset of basis size is a basis II

OpenAIRE

Ball, Simeon; De Beule, Jan

2012-01-01

This article contains a proof of the MDS conjecture for k a parts per thousand currency sign 2p - 2. That is, that if S is a set of vectors of in which every subset of S of size k is a basis, where q = p (h) , p is prime and q is not and k a parts per thousand currency sign 2p - 2, then |S| a parts per thousand currency sign q + 1. It also contains a short proof of the same fact for k a parts per thousand currency sign p, for all q.

Strengthening laboratory systems in resource-limited settings.

Science.gov (United States)

Olmsted, Stuart S; Moore, Melinda; Meili, Robin C; Duber, Herbert C; Wasserman, Jeffrey; Sama, Preethi; Mundell, Ben; Hilborne, Lee H

2010-09-01

Considerable resources have been invested in recent years to improve laboratory systems in resource-limited settings. We reviewed published reports, interviewed major donor organizations, and conducted case studies of laboratory systems in 3 countries to assess how countries and donors have worked together to improve laboratory services. While infrastructure and the provision of services have seen improvement, important opportunities remain for further advancement. Implementation of national laboratory plans is inconsistent, human resources are limited, and quality laboratory services rarely extend to lower tier laboratories (eg, health clinics, district hospitals). Coordination within, between, and among governments and donor organizations is also frequently problematic. Laboratory standardization and quality control are improving but remain challenging, making accreditation a difficult goal. Host country governments and their external funding partners should coordinate their efforts effectively around a host country's own national laboratory plan to advance sustainable capacity development throughout a country's laboratory system.

Crossing the quality chasm in resource-limited settings.

Science.gov (United States)

Maru, Duncan Smith-Rohrberg; Andrews, Jason; Schwarz, Dan; Schwarz, Ryan; Acharya, Bibhav; Ramaiya, Astha; Karelas, Gregory; Rajbhandari, Ruma; Mate, Kedar; Shilpakar, Sona

2012-11-30

Over the last decade, extensive scientific and policy innovations have begun to reduce the "quality chasm"--the gulf between best practices and actual implementation that exists in resource-rich medical settings. While limited data exist, this chasm is likely to be equally acute and deadly in resource-limited areas. While health systems have begun to be scaled up in impoverished areas, scale-up is just the foundation necessary to deliver effective healthcare to the poor. This perspective piece describes a vision for a global quality improvement movement in resource-limited areas. The following action items are a first step toward achieving this vision: 1) revise global health investment mechanisms to value quality; 2) enhance human resources for improving health systems quality; 3) scale up data capacity; 4) deepen community accountability and engagement initiatives; 5) implement evidence-based quality improvement programs; 6) develop an implementation science research agenda.

77 FR 69548 - Price for the 2012 Limited Edition Silver Proof SetTM

Science.gov (United States)

2012-11-19

... DEPARTMENT OF THE TREASURY United States Mint Price for the 2012 Limited Edition Silver Proof Set TM AGENCY: United States Mint, Department of the Treasury. ACTION: Notice. SUMMARY: The United States Mint is announcing a price of $149.95 for the 2012 Limited Edition Silver Proof Set TM . FOR FURTHER...

The static response function in Kohn-Sham theory: An appropriate basis for its matrix representation in case of finite AO basis sets

International Nuclear Information System (INIS)

Kollmar, Christian; Neese, Frank

2014-01-01

The role of the static Kohn-Sham (KS) response function describing the response of the electron density to a change of the local KS potential is discussed in both the theory of the optimized effective potential (OEP) and the so-called inverse Kohn-Sham problem involving the task to find the local KS potential for a given electron density. In a general discussion of the integral equation to be solved in both cases, it is argued that a unique solution of this equation can be found even in case of finite atomic orbital basis sets. It is shown how a matrix representation of the response function can be obtained if the exchange-correlation potential is expanded in terms of a Schmidt-orthogonalized basis comprising orbitals products of occupied and virtual orbitals. The viability of this approach in both OEP theory and the inverse KS problem is illustrated by numerical examples

The biological basis for dose limitation to the skin

International Nuclear Information System (INIS)

Fry, R.J.M.

1992-01-01

Ionizing radiation may cause deterministic effects and cancer. It has been the policy to base dose limits for radiation protection of the skin on the prevention of deterministic effects (1). In the case of cancer in general, dose limitation for radiation protection is based on limiting excess cancer mortality to low levels of radiation. Since skin cancers are seldom lethal, the general radiation protection standards will protect against an increase in excess mortality from skin cancer. However, with the dose limits selected to prevent deterministic effects, there is a significant probability of an excess incidence of skin cancer occurring as a result of exposure during a working lifetime. The induction of skin cancer by radiation is influenced significantly by subsequent exposure to ultraviolet radiation (UVR) from sunlight. This finding raises not only interesting questions about the mechanisms involved, but also about the differences in risk of skin cancer in different populations. The amount and distribution of melanin in the skin determines the degree of the effect of UVR. This paper discusses the mechanisms of the induction of both deterministic and stochastic effects in skin exposed to radiation in relation to radiation protection. (author)

Use of CHROMagar Candida for the presumptive identification of Candida species directly from clinical specimens in resource-limited settings

Science.gov (United States)

Nadeem, Sayyada Ghufrana; Hakim, Shazia Tabassum; Kazmi, Shahana Urooj

2010-01-01

Introduction Identification of yeast isolated from clinical specimens to the species level has become increasingly important. Ever-increasing numbers of immuno-suppressed patients, a widening range of recognized pathogens, and the discovery of resistance to antifungal drugs are contributing factors to this necessity. Material and methods A total of 487 yeast strains were studied for the primary isolation and presumptive identification, directly from clinical specimen. Efficacy of CHROMagar Candida has been evaluated with conventional methods including morphology on Corn meal–tween 80 agar and biochemical methods by using API 20 C AUX. Results The result of this study shows that CHROMagar Candida can easily identify three species of Candida on the basis of colonial color and morphology, and accurately differentiate between them i.e. Candida albicans, Candida tropicalis, and Candida krusei. The specificity and sensitivity of CHROMagar Candida for C. albicans calculated as 99%, for C. tropicalis calculated as 98%, and C. krusei it is 100%. Conclusion The data presented supports the use of CHROMagar Candida for the rapid identification of Candida species directly from clinical specimens in resource-limited settings, which could be very helpful in developing appropriate therapeutic strategy and management of patients. PMID:21483597

Use of CHROMagar Candida for the presumptive identification of Candida species directly from clinical specimens in resource-limited settings

Directory of Open Access Journals (Sweden)

Sayyada Ghufrana Nadeem

2010-02-01

Full Text Available Introduction: Identification of yeast isolated from clinical specimens to the species level has become increasingly important. Ever-increasing numbers of immuno-suppressed patients, a widening range of recognized pathogens, and the discovery of resistance to antifungal drugs are contributing factors to this necessity. Material and methods: A total of 487 yeast strains were studied for the primary isolation and presumptive identification, directly from clinical specimen. Efficacy of CHROMagar Candida has been evaluated with conventional methods including morphology on Corn meal–tween 80 agar and biochemical methods by using API 20 C AUX. Results: The result of this study shows that CHROMagar Candida can easily identify three species of Candida on the basis of colonial color and morphology, and accurately differentiate between them i.e. Candida albicans, Candida tropicalis, and Candida krusei. The specificity and sensitivity of CHROMagar Candida for C. albicans calculated as 99%, for C. tropicalis calculated as 98%, and C. krusei it is 100%. Conclusion: The data presented supports the use of CHROMagar Candida for the rapid identification of Candida species directly from clinical specimens in resource-limited settings, which could be very helpful in developing appropriate therapeutic strategy and management of patients.

Use of CHROMagar Candida for the presumptive identification of Candida species directly from clinical specimens in resource-limited settings.

Science.gov (United States)

Nadeem, Sayyada Ghufrana; Hakim, Shazia Tabassum; Kazmi, Shahana Urooj

2010-02-09

Identification of yeast isolated from clinical specimens to the species level has become increasingly important. Ever-increasing numbers of immuno-suppressed patients, a widening range of recognized pathogens, and the discovery of resistance to antifungal drugs are contributing factors to this necessity. A total of 487 yeast strains were studied for the primary isolation and presumptive identification, directly from clinical specimen. Efficacy of CHROMagar Candida has been evaluated with conventional methods including morphology on Corn meal-tween 80 agar and biochemical methods by using API 20 C AUX. The result of this study shows that CHROMagar Candida can easily identify three species of Candida on the basis of colonial color and morphology, and accurately differentiate between them i.e. Candida albicans, Candida tropicalis, and Candida krusei. The specificity and sensitivity of CHROMagar Candida for C. albicans calculated as 99%, for C. tropicalis calculated as 98%, and C. krusei it is 100%. The data presented supports the use of CHROMagar Candida for the rapid identification of Candida species directly from clinical specimens in resource-limited settings, which could be very helpful in developing appropriate therapeutic strategy and management of patients.

Improved inhalation technology for setting safe exposure levels for workplace chemicals

Science.gov (United States)

Stuart, Bruce O.

1993-01-01

Threshold Limit Values recommended as allowable air concentrations of a chemical in the workplace are often based upon a no-observable-effect-level (NOEL) determined by experimental inhalation studies using rodents. A 'safe level' for human exposure must then be estimated by the use of generalized safety factors in attempts to extrapolate from experimental rodents to man. The recent development of chemical-specific physiologically-based toxicokinetics makes use of measured physiological, biochemical, and metabolic parameters to construct a validated model that is able to 'scale-up' rodent response data to predict the behavior of the chemical in man. This procedure is made possible by recent advances in personal computer software and the emergence of appropriate biological data, and provides an analytical tool for much more reliable risk evaluation and airborne chemical exposure level setting for humans.

The Intermediate Set and Limiting Superdi erential for Coalition Games: Between the Core and the Weber Set

Czech Academy of Sciences Publication Activity Database

Adam, Lukáš; Kroupa, T.

2017-01-01

Roč. 46, č. 4 (2017), s. 891-918 ISSN 0020-7276 R&D Projects: GA ČR GA15-00735S Institutional support: RVO:67985556 Keywords : coalition game * limiting superdi erential * intermediate set * core * Weber set Subject RIV: BA - General Mathematics OBOR OECD: Statistics and probability Impact factor: 0.713, year: 2016 http://library.utia.cas.cz/separaty/2016/MTR/adam-0467365.pdf

Global patient safety and antiretroviral drug-drug interactions in the resource-limited setting.

Science.gov (United States)

Seden, Kay; Khoo, Saye H; Back, David; Byakika-Kibwika, Pauline; Lamorde, Mohammed; Ryan, Mairin; Merry, Concepta

2013-01-01

Scale-up of HIV treatment services may have contributed to an increase in functional health facilities available in resource-limited settings and an increase in patient use of facilities and retention in care. As more patients are reached with medicines, monitoring patient safety is increasingly important. Limited data from resource-limited settings suggest that medication error and antiretroviral drug-drug interactions may pose a significant risk to patient safety. Commonly cited causes of medication error in the developed world include the speed and complexity of the medication use cycle combined with inadequate systems and processes. In resource-limited settings, specific factors may contribute, such as inadequate human resources and high disease burden. Management of drug-drug interactions may be complicated by limited access to alternative medicines or laboratory monitoring. Improving patient safety by addressing the issue of antiretroviral drug-drug interactions has the potential not just to improve healthcare for individuals, but also to strengthen health systems and improve vital communication among healthcare providers and with regulatory agencies.

Risk newsboy: approach for addressing uncertainty in developing action levels and cleanup limits

International Nuclear Information System (INIS)

Cooke, Roger; MacDonell, Margaret

2007-01-01

Site cleanup decisions involve developing action levels and residual limits for key contaminants, to assure health protection during the cleanup period and into the long term. Uncertainty is inherent in the toxicity information used to define these levels, based on incomplete scientific knowledge regarding dose-response relationships across various hazards and exposures at environmentally relevant levels. This problem can be addressed by applying principles used to manage uncertainty in operations research, as illustrated by the newsboy dilemma. Each day a newsboy must balance the risk of buying more papers than he can sell against the risk of not buying enough. Setting action levels and cleanup limits involves a similar concept of balancing and distributing risks and benefits in the face of uncertainty. The newsboy approach can be applied to develop health-based target concentrations for both radiological and chemical contaminants, with stakeholder input being crucial to assessing 'regret' levels. Associated tools include structured expert judgment elicitation to quantify uncertainty in the dose-response relationship, and mathematical techniques such as probabilistic inversion and iterative proportional fitting. (authors)

Velocity-gauge real-time TDDFT within a numerical atomic orbital basis set

Science.gov (United States)

Pemmaraju, C. D.; Vila, F. D.; Kas, J. J.; Sato, S. A.; Rehr, J. J.; Yabana, K.; Prendergast, David

2018-05-01

The interaction of laser fields with solid-state systems can be modeled efficiently within the velocity-gauge formalism of real-time time dependent density functional theory (RT-TDDFT). In this article, we discuss the implementation of the velocity-gauge RT-TDDFT equations for electron dynamics within a linear combination of atomic orbitals (LCAO) basis set framework. Numerical results obtained from our LCAO implementation, for the electronic response of periodic systems to both weak and intense laser fields, are compared to those obtained from established real-space grid and Full-Potential Linearized Augmented Planewave approaches. Potential applications of the LCAO based scheme in the context of extreme ultra-violet and soft X-ray spectroscopies involving core-electronic excitations are discussed.

Characterizing omega-limit sets which are closed orbits

Science.gov (United States)

Bautista, S.; Morales, C.

Let X be a vector field in a compact n-manifold M, n⩾2. Given Σ⊂M we say that q∈M satisfies (P) Σ if the closure of the positive orbit of X through q does not intersect Σ, but, however, there is an open interval I with q as a boundary point such that every positive orbit through I intersects Σ. Among those q having saddle-type hyperbolic omega-limit set ω(q) the ones with ω(q) being a closed orbit satisfy (P) Σ for some closed subset Σ. The converse is true for n=2 but not for n⩾4. Here we prove the converse for n=3. Moreover, we prove for n=3 that if ω(q) is a singular-hyperbolic set [C. Morales, M. Pacifico, E. Pujals, On C robust singular transitive sets for three-dimensional flows, C. R. Acad. Sci. Paris Sér. I 26 (1998) 81-86], [C. Morales, M. Pacifico, E. Pujals, Robust transitive singular sets for 3-flows are partially hyperbolic attractors or repellers, Ann. of Math. (2) 160 (2) (2004) 375-432], then ω(q) is a closed orbit if and only if q satisfies (P) Σ for some Σ closed. This result improves [S. Bautista, Sobre conjuntos hiperbólicos-singulares (On singular-hyperbolic sets), thesis Uiversidade Federal do Rio de Janeiro, 2005 (in Portuguese)] and [C. Morales, M. Pacifico, Mixing attractors for 3-flows, Nonlinearity 14 (2001) 359-378].

Upper Limit for Regional Sea Level Projections

Science.gov (United States)

Jevrejeva, Svetlana; Jackson, Luke; Riva, Riccardo; Grinsted, Aslak; Moore, John

2016-04-01

With more than 150 million people living within 1 m of high tide future sea level rise is one of the most damaging aspects of warming climate. The latest Intergovernmental Panel on Climate Change report (AR5 IPCC) noted that a 0.5 m rise in mean sea level will result in a dramatic increase the frequency of high water extremes - by an order of magnitude, or more in some regions. Thus the flood threat to the rapidly growing urban populations and associated infrastructure in coastal areas are major concerns for society. Hence, impact assessment, risk management, adaptation strategy and long-term decision making in coastal areas depend on projections of mean sea level and crucially its low probability, high impact, upper range. With probabilistic approach we produce regional sea level projections taking into account large uncertainties associated with Greenland and Antarctica ice sheets contribution. We calculate the upper limit (as 95%) for regional sea level projections by 2100 with RCP8.5 scenario, suggesting that for the most coastlines upper limit will exceed the global upper limit of 1.8 m.

On multiple level-set regularization methods for inverse problems

International Nuclear Information System (INIS)

DeCezaro, A; Leitão, A; Tai, X-C

2009-01-01

We analyze a multiple level-set method for solving inverse problems with piecewise constant solutions. This method corresponds to an iterated Tikhonov method for a particular Tikhonov functional G α based on TV–H 1 penalization. We define generalized minimizers for our Tikhonov functional and establish an existence result. Moreover, we prove convergence and stability results of the proposed Tikhonov method. A multiple level-set algorithm is derived from the first-order optimality conditions for the Tikhonov functional G α , similarly as the iterated Tikhonov method. The proposed multiple level-set method is tested on an inverse potential problem. Numerical experiments show that the method is able to recover multiple objects as well as multiple contrast levels

A level set method for multiple sclerosis lesion segmentation.

Science.gov (United States)

Zhao, Yue; Guo, Shuxu; Luo, Min; Shi, Xue; Bilello, Michel; Zhang, Shaoxiang; Li, Chunming

2018-06-01

In this paper, we present a level set method for multiple sclerosis (MS) lesion segmentation from FLAIR images in the presence of intensity inhomogeneities. We use a three-phase level set formulation of segmentation and bias field estimation to segment MS lesions and normal tissue region (including GM and WM) and CSF and the background from FLAIR images. To save computational load, we derive a two-phase formulation from the original multi-phase level set formulation to segment the MS lesions and normal tissue regions. The derived method inherits the desirable ability to precisely locate object boundaries of the original level set method, which simultaneously performs segmentation and estimation of the bias field to deal with intensity inhomogeneity. Experimental results demonstrate the advantages of our method over other state-of-the-art methods in terms of segmentation accuracy. Copyright © 2017 Elsevier Inc. All rights reserved.

Perturbation expansion theory corrected from basis set superposition error. I. Locally projected excited orbitals and single excitations.

Science.gov (United States)

Nagata, Takeshi; Iwata, Suehiro

2004-02-22

The locally projected self-consistent field molecular orbital method for molecular interaction (LP SCF MI) is reformulated for multifragment systems. For the perturbation expansion, two types of the local excited orbitals are defined; one is fully local in the basis set on a fragment, and the other has to be partially delocalized to the basis sets on the other fragments. The perturbation expansion calculations only within single excitations (LP SE MP2) are tested for water dimer, hydrogen fluoride dimer, and colinear symmetric ArM+ Ar (M = Na and K). The calculated binding energies of LP SE MP2 are all close to the corresponding counterpoise corrected SCF binding energy. By adding the single excitations, the deficiency in LP SCF MI is thus removed. The results suggest that the exclusion of the charge-transfer effects in LP SCF MI might indeed be the cause of the underestimation for the binding energy. (c) 2004 American Institute of Physics.

Some free boundary problems in potential flow regime usinga based level set method

Energy Technology Data Exchange (ETDEWEB)

Garzon, M.; Bobillo-Ares, N.; Sethian, J.A.

2008-12-09

Recent advances in the field of fluid mechanics with moving fronts are linked to the use of Level Set Methods, a versatile mathematical technique to follow free boundaries which undergo topological changes. A challenging class of problems in this context are those related to the solution of a partial differential equation posed on a moving domain, in which the boundary condition for the PDE solver has to be obtained from a partial differential equation defined on the front. This is the case of potential flow models with moving boundaries. Moreover the fluid front will possibly be carrying some material substance which will diffuse in the front and be advected by the front velocity, as for example the use of surfactants to lower surface tension. We present a Level Set based methodology to embed this partial differential equations defined on the front in a complete Eulerian framework, fully avoiding the tracking of fluid particles and its known limitations. To show the advantages of this approach in the field of Fluid Mechanics we present in this work one particular application: the numerical approximation of a potential flow model to simulate the evolution and breaking of a solitary wave propagating over a slopping bottom and compare the level set based algorithm with previous front tracking models.

A parametric level-set method for partially discrete tomography

NARCIS (Netherlands)

A. Kadu (Ajinkya); T. van Leeuwen (Tristan); K.J. Batenburg (Joost)

2017-01-01

textabstractThis paper introduces a parametric level-set method for tomographic reconstruction of partially discrete images. Such images consist of a continuously varying background and an anomaly with a constant (known) grey-value. We express the geometry of the anomaly using a level-set function,

Sulfonylurea herbicides – methodological challenges in setting aquatic limit values

DEFF Research Database (Denmark)

Rosenkrantz, Rikke Tjørnhøj; Baun, Anders; Kusk, Kresten Ole

according to the EU Water Framework Directive, the resulting Water Quality Standards (WQSs) are below the analytical quantification limit, making it difficult to verify compliance with the limit values. However, several methodological concerns may be raised in relation to the very low effect concentrations...... and rimsulfuron. The following parameters were varied during testing: pH, exposure duration, temperature and light/dark cycle. Preliminary results show that a decrease in pH causes an increase in toxicity for all compounds. Exposure to a high concentration for 24 hours caused a reduction in growth rate, from...... for setting limit values for SUs or if more detailed information should be gained by taking methodological considerations into account....

Exploration of the NH3-H2 van der Waals interaction by high level ab initio calculations

International Nuclear Information System (INIS)

Mladenovic, Mirjana; Lewerenz, Marius; Cilpa, Geraldine; Rosmus, Pavel; Chambaud, Gilberte

2008-01-01

The intermolecular potential energy for the van der Waals complex between ammonia and the hydrogen molecule has been studied by means of the coupled cluster CCSD(T) method and aug-cc-pVXZ (X = D, T, Q, 5) basis sets and with inclusion of the Boys and Bernardi counterpoise correction. For sufficiently large basis sets the only true electronic minimum energy structure of NH 3 -H 2 is found to possess C 3v point group symmetry. Various minimum energy paths for the relative motion of NH 3 and H 2 are analysed in order to understand the topography of the intermolecular potential. The complete basis set limit for the electronic dissociation energy is estimated to be about 253 cm -1 at the CCSD(T) level

International Neurocognitive Normative Study: Neurocognitive Comparison Data in Diverse Resource Limited Settings: AIDS Clinical Trials Group A5271

Science.gov (United States)

Robertson, K; Jiang, H; Evans, SR; Marra, CM; Berzins, B; Hakim, J; Sacktor, N; Silva, M Tulius; Campbell, TB; Nair, A; Schouten, J; Kumwenda, J; Supparatpinyo, K; Tripathy, S.; Kumarasamy, N; La Rosa, A; Montano, S; Mwafongo, A; Firnhaber, C; Sanne, I; Naini, L.; Amod, F; Walawander, A

2016-01-01

Summary ACTG A5271 collected neurocognitive normative comparison test data in 2400 at-risk HIV seronegative participants from Brazil, India, Malawi, Peru, South Africa, Thailand and Zimbabwe. The participants were enrolled in strata by site (10 levels), age (2 levels), education (2 levels), and gender (2 levels). These data provide necessary normative data infrastructure for future clinical research and care in these diverse resource limited settings. Infrastructure for conducting neurological research in resource limited settings (RLS) is limited. The lack of neurological and neuropsychological (NP) assessment, and normative data needed for clinical interpretation impede research and clinical care. Here we report on ACTG 5271, which provided neurological training of clinical site personnel, and collected neurocognitive normative comparison data in diverse settings. At 10 sites in seven RLS countries, we provided training for NP assessments. We collected normative comparison data on HIV- participants from Brazil (n=240), India (n=480), Malawi (n=481), Peru (n=239), South Africa (480), Thailand (n=240) and Zimbabwe (n=240). Participants had a negative HIV test within 30 days before standardized NP exams were administered at baseline, and 770 at six-months. Participants were enrolled in 8 strata, gender (female and male), education (<10 years and ≥ 10 years), and age (<35 years and ≥35 years). Of 2400 enrolled, 770 completed the six-month follow up. As expected, significant between-country differences were evident in all the neurocognitive test scores (p<.0001). There was variation between the age, gender and education strata on the neurocognitive tests. Age and education were important variables for all tests; older participants had poorer performance and those with higher education had better performance. Women had better performance on verbal learning/memory and speed of processing tests, while men performed better on motor tests. This study provides the

Diesel Engine Exhaust: Basis for Occupational Exposure Limit Value.

Science.gov (United States)

Taxell, Piia; Santonen, Tiina

2017-08-01

Diesel engines are widely used in transport and power supply, making occupational exposure to diesel exhaust common. Both human and animal studies associate exposure to diesel exhaust with inflammatory lung effects, cardiovascular effects, and an increased risk of lung cancer. The International Agency for Research on Cancer has evaluated diesel exhaust as carcinogenic to humans. Yet national or regional limit values for controlling occupational exposure to diesel exhaust are rare. In recent decades, stricter emission regulations have led to diesel technologies evolving significantly, resulting in changes in exhaust emissions and composition. These changes are also expected to influence the health effects of diesel exhaust. This review provides an overview of the current knowledge on the health effects of diesel exhaust and the influence of new diesel technologies on the health risk. It discusses the relevant exposure indicators and perspectives for setting occupational exposure limit values for diesel exhaust, and outlines directions for future research. The review is based on a collaborative evaluation report by the Nordic Expert Group for Criteria Documentation of Health Risks from Chemicals and the Dutch Expert Committee on Occupational Safety. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Structural level set inversion for microwave breast screening

International Nuclear Information System (INIS)

Irishina, Natalia; Álvarez, Diego; Dorn, Oliver; Moscoso, Miguel

2010-01-01

We present a new inversion strategy for the early detection of breast cancer from microwave data which is based on a new multiphase level set technique. This novel structural inversion method uses a modification of the color level set technique adapted to the specific situation of structural breast imaging taking into account the high complexity of the breast tissue. We only use data of a few microwave frequencies for detecting the tumors hidden in this complex structure. Three level set functions are employed for describing four different types of breast tissue, where each of these four regions is allowed to have a complicated topology and to have an interior structure which needs to be estimated from the data simultaneously with the region interfaces. The algorithm consists of several stages of increasing complexity. In each stage more details about the anatomical structure of the breast interior is incorporated into the inversion model. The synthetic breast models which are used for creating simulated data are based on real MRI images of the breast and are therefore quite realistic. Our results demonstrate the potential and feasibility of the proposed level set technique for detecting, locating and characterizing a small tumor in its early stage of development embedded in such a realistic breast model. Both the data acquisition simulation and the inversion are carried out in 2D

Setting limits on Effective Field Theories: the case of Dark Matter

Science.gov (United States)

Pobbe, Federico; Wulzer, Andrea; Zanetti, Marco

2017-08-01

The usage of Effective Field Theories (EFT) for LHC new physics searches is receiving increasing attention. It is thus important to clarify all the aspects related with the applicability of the EFT formalism in the LHC environment, where the large available energy can produce reactions that overcome the maximal range of validity, i.e. the cutoff, of the theory. We show that this does not forbid to set rigorous limits on the EFT parameter space through a modified version of the ordinary binned likelihood hypothesis test, which we design and validate. Our limit-setting strategy can be carried on in its full-fledged form by the LHC experimental collaborations, or performed externally to the collaborations, through the Simplified Likelihood approach, by relying on certain approximations. We apply it to the recent CMS mono-jet analysis and derive limits on a Dark Matter (DM) EFT model. DM is selected as a case study because the limited reach on the DM production EFT Wilson coefficient and the structure of the theory suggests that the cutoff might be dangerously low, well within the LHC reach. However our strategy can also be applied, if needed, to EFT's parametrising the indirect effects of heavy new physics in the Electroweak and Higgs sectors.

Fluoroscopy in paediatric fractures - Setting a local diagnostic reference level

International Nuclear Information System (INIS)

Pillai, A.; McAuley, A.; McMurray, K.; Jain, M.

2006-01-01

Background: The ionizing radiations (Medical Exposure) Regulation 2000 has made it mandatory to establish diagnostic reference levels (DRLs) for all typical radiological examinations. Objectives: We attempt to provide dose data for some common fluoroscopic procedures used in orthopaedic trauma that may be used as the basis for setting DRLs for paediatric patients. Materials and methods: The dose area product (DAP) in 865 paediatric trauma examinations was analysed. Median DAP values and screening times for each procedure type along with quartile values for each range are presented. Results: In the upper limb, elbow examinations had maximum exposure with a median DAP value of 1.21 cGy cm 2 . Median DAP values for forearm and wrist examinations were 0.708 and 0.538 cGy cm 2 , respectively. In lower limb, tibia and fibula examinations had a median DAP value of 3.23 cGy cm 2 followed by ankle examinations with a median DAP of 3.10 cGy cm 2 . The rounded third quartile DAP value for each distribution can be used as a provisional DRL for the specific procedure type. (authors)

Limited parameter set IMRT for carcinoma breast

International Nuclear Information System (INIS)

Gopinath, M.; Sharma, Sanjiv; Vivek, T.R.; Suparna; Deka, Preeti; Manikandan; Giriraj

2008-01-01

Post operative radiotherapy after breast conservation surgery is an effective and widely accepted treatment modality in early stage breast cancer. The treatment is usually performed using two wedged tangential photon beams. The disadvantage of this technique is significant dose inhomogeneity as large as 15-20% in the superior and inferior regions of the breast due to lesser transmission thickness and in the medial and lateral aspect of the breast due to lower attenuation of lung tissue in the field. The aim of the study is to modify the conventional wedged tangential pair to achieve a more homogeneous dose distribution and a reduction in acute toxicity and improved cosmetic result. A comparative study is done between the conventional wedged technique and limited parameter set IMRT

Chemical bonding analysis for solid-state systems using intrinsic oriented quasiatomic minimal-basis-set orbitals

International Nuclear Information System (INIS)

Yao, Y.X.; Wang, C.Z.; Ho, K.M.

2010-01-01

A chemical bonding scheme is presented for the analysis of solid-state systems. The scheme is based on the intrinsic oriented quasiatomic minimal-basis-set orbitals (IO-QUAMBOs) previously developed by Ivanic and Ruedenberg for molecular systems. In the solid-state scheme, IO-QUAMBOs are generated by a unitary transformation of the quasiatomic orbitals located at each site of the system with the criteria of maximizing the sum of the fourth power of interatomic orbital bond order. Possible bonding and antibonding characters are indicated by the single particle matrix elements, and can be further examined by the projected density of states. We demonstrate the method by applications to graphene and (6,0) zigzag carbon nanotube. The oriented-orbital scheme automatically describes the system in terms of sp 2 hybridization. The effect of curvature on the electronic structure of the zigzag carbon nanotube is also manifested in the deformation of the intrinsic oriented orbitals as well as a breaking of symmetry leading to nonzero single particle density matrix elements. In an additional study, the analysis is performed on the Al 3 V compound. The main covalent bonding characters are identified in a straightforward way without resorting to the symmetry analysis. Our method provides a general way for chemical bonding analysis of ab initio electronic structure calculations with any type of basis sets.

The 6-31B(d) basis set and the BMC-QCISD and BMC-CCSD multicoefficient correlation methods.

Science.gov (United States)

Lynch, Benjamin J; Zhao, Yan; Truhlar, Donald G

2005-03-03

Three new multicoefficient correlation methods (MCCMs) called BMC-QCISD, BMC-CCSD, and BMC-CCSD-C are optimized against 274 data that include atomization energies, electron affinities, ionization potentials, and reaction barrier heights. A new basis set called 6-31B(d) is developed and used as part of the new methods. BMC-QCISD has mean unsigned errors in calculating atomization energies per bond and barrier heights of 0.49 and 0.80 kcal/mol, respectively. BMC-CCSD has mean unsigned errors of 0.42 and 0.71 kcal/mol for the same two quantities. BMC-CCSD-C is an equally effective variant of BMC-CCSD that employs Cartesian rather than spherical harmonic basis sets. The mean unsigned error of BMC-CCSD or BMC-CCSD-C for atomization energies, barrier heights, ionization potentials, and electron affinities is 22% lower than G3SX(MP2) at an order of magnitude less cost for gradients for molecules with 9-13 atoms, and it scales better (N6 vs N,7 where N is the number of atoms) when the size of the molecule is increased.

Formation and physical characteristics of van der Waals molecules, cations, and anions: Estimates of complete basis set values

Czech Academy of Sciences Publication Activity Database

Zahradník, Rudolf; Šroubková, Libuše

2005-01-01

Roč. 104, č. 1 (2005), s. 52-63 ISSN 0020-7608 Institutional research plan: CEZ:AV0Z40400503 Keywords : intermolecular complexes * van der Waals species * ab initio calculations * complete basis set values * estimates Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.192, year: 2005

Evaluating Diagnostic Point-of-Care Tests in Resource-Limited Settings

Science.gov (United States)

Drain, Paul K; Hyle, Emily P; Noubary, Farzad; Freedberg, Kenneth A; Wilson, Douglas; Bishai, William; Rodriguez, William; Bassett, Ingrid V

2014-01-01

Diagnostic point-of-care (POC) testing is intended to minimize the time to obtain a test result, thereby allowing clinicians and patients to make an expeditious clinical decision. As POC tests expand into resource-limited settings (RLS), the benefits must outweigh the costs. To optimize POC testing in RLS, diagnostic POC tests need rigorous evaluations focused on relevant clinical outcomes and operational costs, which differ from evaluations of conventional diagnostic tests. Here, we reviewed published studies on POC testing in RLS, and found no clearly defined metric for the clinical utility of POC testing. Therefore, we propose a framework for evaluating POC tests, and suggest and define the term “test efficacy” to describe a diagnostic test’s capacity to support a clinical decision within its operational context. We also proposed revised criteria for an ideal diagnostic POC test in resource-limited settings. Through systematic evaluations, comparisons between centralized diagnostic testing and novel POC technologies can be more formalized, and health officials can better determine which POC technologies represent valuable additions to their clinical programs. PMID:24332389

OBESITY OF ADULTS LIVING IN THE URBAN SETTINGS AS BASIS FOR DIFFERENT APPLICATIONS OF RECREATIONAL SPORTS

Directory of Open Access Journals (Sweden)

Vesko Drašković

2008-08-01

Full Text Available According to the World Health Organization’s data, obesity is one of the main risk factors for the human health, especially in so called “mature age”, that is in forties and fiftees of the human’s life. There are many causes of obesity, and the most common ones are unadequate or excessive nutrition, low quality food rich in fats and highly caloric sweetener, unsufficient physical activity – hypokinesy, but also technical and technological development of the modern World (TV, cell phones, elevators, cars etc.. The objective of this research is to define the obesity of adults living in the urban settings through BMI (body mass index and to create, on the basis of these findings, the basis for different applications of the recreational sports programme.

An evolutionary algorithm for tomographic reconstructions in limited data sets problems

International Nuclear Information System (INIS)

Turcanu, Catrinel; Craciunescu, Teddy

2000-01-01

The paper proposes a new method for tomographic reconstructions. Unlike nuclear medicine applications, in physical science problems we are often confronted with limited data sets: constraints in the number of projections or limited angle views. The problem of image reconstruction from projections may be considered as a problem of finding an image (solution) having projections that match the experimental ones. In our approach, we choose a statistical correlation coefficient to evaluate the fitness of any potential solution. The optimization process is carried out by an evolutionary algorithm. Our algorithm has some problem-oriented characteristics. One of them is that a chromosome, representing a potential solution, is not linear but coded as a matrix of pixels corresponding to a two-dimensional image. This kind of internal representation reflects the genuine manifestation and slight differences between two points situated in the original problem space give rise to similar differences once they become coded. Another particular feature is a newly built crossover operator: the grid-based crossover, suitable for high dimension two-dimensional chromosomes. Except for the population size and the dimension of the cutting grid for the grid-based crossover, all the other parameters of the algorithm are independent of the geometry of the tomographic reconstruction. The performances of the method are evaluated in comparison with a traditional tomographic method, based on the maximization of the entropy of the image, that proved to work well with limited data sets. The test phantom is typical for an application with limited data sets: the determination of the neutron energy spectra with time resolution in case of short-pulsed neutron emission. The qualitative judgement and also the quantitative one, based on some figures of merit, point out that the proposed method ensures an improved reconstruction of shapes, sizes and resolution in the image, even in the presence of noise

Limited Effects of Set Shifting Training in Healthy Older Adults

Directory of Open Access Journals (Sweden)

Petra Grönholm-Nyman

2017-03-01

Full Text Available Our ability to flexibly shift between tasks or task sets declines in older age. As this decline may have adverse effects on everyday life of elderly people, it is of interest to study whether set shifting ability can be trained, and if training effects generalize to other cognitive tasks. Here, we report a randomized controlled trial where healthy older adults trained set shifting with three different set shifting tasks. The training group (n = 17 performed adaptive set shifting training for 5 weeks with three training sessions a week (45 min/session, while the active control group (n = 16 played three different computer games for the same period. Both groups underwent extensive pre- and post-testing and a 1-year follow-up. Compared to the controls, the training group showed significant improvements on the trained tasks. Evidence for near transfer in the training group was very limited, as it was seen only on overall accuracy on an untrained computerized set shifting task. No far transfer to other cognitive functions was observed. One year later, the training group was still better on the trained tasks but the single near transfer effect had vanished. The results suggest that computerized set shifting training in the elderly shows long-lasting effects on the trained tasks but very little benefit in terms of generalization.

Discretisation Schemes for Level Sets of Planar Gaussian Fields

Science.gov (United States)

Beliaev, D.; Muirhead, S.

2018-01-01

Smooth random Gaussian functions play an important role in mathematical physics, a main example being the random plane wave model conjectured by Berry to give a universal description of high-energy eigenfunctions of the Laplacian on generic compact manifolds. Our work is motivated by questions about the geometry of such random functions, in particular relating to the structure of their nodal and level sets. We study four discretisation schemes that extract information about level sets of planar Gaussian fields. Each scheme recovers information up to a different level of precision, and each requires a maximum mesh-size in order to be valid with high probability. The first two schemes are generalisations and enhancements of similar schemes that have appeared in the literature (Beffara and Gayet in Publ Math IHES, 2017. https://doi.org/10.1007/s10240-017-0093-0; Mischaikow and Wanner in Ann Appl Probab 17:980-1018, 2007); these give complete topological information about the level sets on either a local or global scale. As an application, we improve the results in Beffara and Gayet (2017) on Russo-Seymour-Welsh estimates for the nodal set of positively-correlated planar Gaussian fields. The third and fourth schemes are, to the best of our knowledge, completely new. The third scheme is specific to the nodal set of the random plane wave, and provides global topological information about the nodal set up to `visible ambiguities'. The fourth scheme gives a way to approximate the mean number of excursion domains of planar Gaussian fields.

Identifying Heterogeneities in Subsurface Environment using the Level Set Method

Energy Technology Data Exchange (ETDEWEB)

Lei, Hongzhuan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lu, Zhiming [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vesselinov, Velimir Valentinov [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-08-25

These are slides from a presentation on identifying heterogeneities in subsurface environment using the level set method. The slides start with the motivation, then explain Level Set Method (LSM), the algorithms, some examples are given, and finally future work is explained.

Surface interpolation with radial basis functions for medical imaging

International Nuclear Information System (INIS)

Carr, J.C.; Beatson, R.K.; Fright, W.R.

1997-01-01

Radial basis functions are presented as a practical solution to the problem of interpolating incomplete surfaces derived from three-dimensional (3-D) medical graphics. The specific application considered is the design of cranial implants for the repair of defects, usually holes, in the skull. Radial basis functions impose few restrictions on the geometry of the interpolation centers and are suited to problems where interpolation centers do not form a regular grid. However, their high computational requirements have previously limited their use to problems where the number of interpolation centers is small (<300). Recently developed fast evaluation techniques have overcome these limitations and made radial basis interpolation a practical approach for larger data sets. In this paper radial basis functions are fitted to depth-maps of the skull's surface, obtained from X-ray computed tomography (CT) data using ray-tracing techniques. They are used to smoothly interpolate the surface of the skull across defect regions. The resulting mathematical description of the skull's surface can be evaluated at any desired resolution to be rendered on a graphics workstation or to generate instructions for operating a computer numerically controlled (CNC) mill

Setting-level influences on implementation of the responsive classroom approach.

Science.gov (United States)

Wanless, Shannon B; Patton, Christine L; Rimm-Kaufman, Sara E; Deutsch, Nancy L

2013-02-01

We used mixed methods to examine the association between setting-level factors and observed implementation of a social and emotional learning intervention (Responsive Classroom® approach; RC). In study 1 (N = 33 3rd grade teachers after the first year of RC implementation), we identified relevant setting-level factors and uncovered the mechanisms through which they related to implementation. In study 2 (N = 50 4th grade teachers after the second year of RC implementation), we validated our most salient Study 1 finding across multiple informants. Findings suggested that teachers perceived setting-level factors, particularly principal buy-in to the intervention and individualized coaching, as influential to their degree of implementation. Further, we found that intervention coaches' perspectives of principal buy-in were more related to implementation than principals' or teachers' perspectives. Findings extend the application of setting theory to the field of implementation science and suggest that interventionists may want to consider particular accounts of school setting factors before determining the likelihood of schools achieving high levels of implementation.

Voluntary limit setting and player choice in most intense online gamblers: an empirical study of gambling behaviour.

Science.gov (United States)

Auer, Michael; Griffiths, Mark D

2013-12-01

Social responsibility in gambling has become a major issue for the gaming industry. The possibility for online gamblers to set voluntary time and money limits are a social responsibility practice that is now widespread among online gaming operators. The main issue concerns whether the voluntary setting of such limits has any positive impact on subsequent gambling behaviour and whether such measures are of help to problem gamblers. In this paper, this issue is examined through data collected from a representative random sample of 100,000 players who gambled on the win2day gambling website. When opening an account at the win2day site, there is a mandatory requirement for all players to set time and cash-in limits (that cannot exceed 800 per week). During a 3-month period, all voluntary time and/or money limit setting behaviour by a subsample of online gamblers (n = 5,000) within this mandatory framework was tracked and recorded for subsequent data analysis. From the 5,000 gamblers, the 10 % most intense players (as measured by theoretical loss) were further investigated. Voluntary spending limits had the highest significant effect on subsequent monetary spending among casino and lottery gamblers. Monetary spending among poker players significantly decreased after setting a voluntary time limit. The highest significant decrease in playing duration was among poker players after setting a voluntary playing duration limit. The results of the study demonstrated that voluntary limit setting had a specific and significant effect on the studied gamblers. Therefore, voluntary limits appear to show an appropriate effect in the desired target group (i.e., the most gaming intense players).

Structural basis for inhibition of the histone chaperone activity of SET/TAF-Iβ by cytochrome c.

Science.gov (United States)

González-Arzola, Katiuska; Díaz-Moreno, Irene; Cano-González, Ana; Díaz-Quintana, Antonio; Velázquez-Campoy, Adrián; Moreno-Beltrán, Blas; López-Rivas, Abelardo; De la Rosa, Miguel A

2015-08-11

Chromatin is pivotal for regulation of the DNA damage process insofar as it influences access to DNA and serves as a DNA repair docking site. Recent works identify histone chaperones as key regulators of damaged chromatin's transcriptional activity. However, understanding how chaperones are modulated during DNA damage response is still challenging. This study reveals that the histone chaperone SET/TAF-Iβ interacts with cytochrome c following DNA damage. Specifically, cytochrome c is shown to be translocated into cell nuclei upon induction of DNA damage, but not upon stimulation of the death receptor or stress-induced pathways. Cytochrome c was found to competitively hinder binding of SET/TAF-Iβ to core histones, thereby locking its histone-binding domains and inhibiting its nucleosome assembly activity. In addition, we have used NMR spectroscopy, calorimetry, mutagenesis, and molecular docking to provide an insight into the structural features of the formation of the complex between cytochrome c and SET/TAF-Iβ. Overall, these findings establish a framework for understanding the molecular basis of cytochrome c-mediated blocking of SET/TAF-Iβ, which subsequently may facilitate the development of new drugs to silence the oncogenic effect of SET/TAF-Iβ's histone chaperone activity.

Multi-phase flow monitoring with electrical impedance tomography using level set based method

International Nuclear Information System (INIS)

Liu, Dong; Khambampati, Anil Kumar; Kim, Sin; Kim, Kyung Youn

2015-01-01

Highlights: • LSM has been used for shape reconstruction to monitor multi-phase flow using EIT. • Multi-phase level set model for conductivity is represented by two level set functions. • LSM handles topological merging and breaking naturally during evolution process. • To reduce the computational time, a narrowband technique was applied. • Use of narrowband and optimization approach results in efficient and fast method. - Abstract: In this paper, a level set-based reconstruction scheme is applied to multi-phase flow monitoring using electrical impedance tomography (EIT). The proposed scheme involves applying a narrowband level set method to solve the inverse problem of finding the interface between the regions having different conductivity values. The multi-phase level set model for the conductivity distribution inside the domain is represented by two level set functions. The key principle of the level set-based method is to implicitly represent the shape of interface as the zero level set of higher dimensional function and then solve a set of partial differential equations. The level set-based scheme handles topological merging and breaking naturally during the evolution process. It also offers several advantages compared to traditional pixel-based approach. Level set-based method for multi-phase flow is tested with numerical and experimental data. It is found that level set-based method has better reconstruction performance when compared to pixel-based method

Reaching the end of the line: Operational issues with implementing phone-based unannounced pill counts in resource-limited settings.

Directory of Open Access Journals (Sweden)

Yael Hirsch-Moverman

Full Text Available Accurate measurement of adherence is necessary to ensure that therapeutic outcomes can be attributed to the recommended treatment. Phone-based unannounced pill counts were shown to be feasible and reliable measures of adherence in developed settings; and have been further used as part of medication adherence interventions. However, it is not clear whether this method can be implemented successfully in resource-limited settings, where cellular network and mobile phone coverage may be low. Our objective is to describe operational issues surrounding the use of phone-based unannounced pill counts in Lesotho and Ethiopia.Phone-based monthly unannounced pill counts, using an adaptation of a standardized protocol from previous US-based studies, were utilized to measure anti-TB and antiretroviral medication adherence in two implementation science studies in resource-limited settings, START (Lesotho and ENRICH (Ethiopia.In START, 19.6% of calls were completed, with 71.9% of participants reached at least once; majority of failed call attempts were due to phones not being available (54.8% or because participants were away from the pills (32.7%. In ENRICH, 33.5% of calls were completed, with 86.7% of participants reached at least once; the main reasons for failed call attempts were phones being switched off (31.5%, participants not answering (27.3%, participants' discomfort speaking on the phone (15.4%, and network problems (13.2%. Structural, facility-level, participant-level, and data collection challenges were encountered in these settings.Phone-based unannounced pill counts were found to be challenging, and response rates suboptimal. While some of these challenges were specific to local contexts, most of them are generalizable to resource-limited settings. In a research study context, a possible solution to ease operational challenges may be to focus phone-based unannounced pill count efforts on a randomly selected sample from participants who are

Fatigue and Serviceability Limit State Model Basis for Assessment of Offshore Wind Energy Converters

DEFF Research Database (Denmark)

Thöns, Sebastian; Faber, M. H.; Rücker, W.

2012-01-01

, a probabilistic model is derived on the basis of literature review and measurement data from a prototype Multibrid M5000 support structure. The sensitivity study is based on the calculation of a nonlinear coefficient of correlation in conjunction with predetermined designs of experiments. This is conducted......This paper develops the models for the structural performance of the loading and probabilistic characterization for the fatigue and the serviceability limit states for the support structure of offshore wind energy converters. These models and a sensitivity study are part of a risk based assessment...... as the starting point for the development of the structural performance and loading models. With these models introduced in detail, several modeling aspects for both limit states are analyzed. This includes analyses of the influence on the hot spot stresses by applying a contact formulation for the pile guide...

Level Set Structure of an Integrable Cellular Automaton

Directory of Open Access Journals (Sweden)

Taichiro Takagi

2010-03-01

Full Text Available Based on a group theoretical setting a sort of discrete dynamical system is constructed and applied to a combinatorial dynamical system defined on the set of certain Bethe ansatz related objects known as the rigged configurations. This system is then used to study a one-dimensional periodic cellular automaton related to discrete Toda lattice. It is shown for the first time that the level set of this cellular automaton is decomposed into connected components and every such component is a torus.

Lithium photoionization cross-section and dynamic polarizability using square integrable basis sets and correlated wave functions

International Nuclear Information System (INIS)

Hollauer, E.; Nascimento, M.A.C.

1985-01-01

The photoionization cross-section and dynamic polarizability for lithium atom are calculated using a discrete basis set to represent both the bound and the continuum-states of the atom, to construct an approximation to the dynamic polarizability. From the imaginary part of the complex dynamic polarizability one extracts the photoionization cross-section and from its real part the dynamic polarizability. The results are in good agreement with the experiments and other more elaborate calculations (Author) [pt

Relationship between perceived limit-setting abilities, autism spectrum disorder severity, behaviour problems and parenting stress in mothers of children with autism spectrum disorder.

Science.gov (United States)

Reed, Phil; Howse, Jessie; Ho, Ben; Osborne, Lisa A

2017-11-01

Parenting stress in mothers of children with autism spectrum disorder (ASD) is high and impacts perceptions about parenting. This study examined the relationship between parenting stress and observer-perceived limit-setting ability. Participants' perceptions of other parents' limit-setting ability were assessed by showing participants video clips of parenting behaviours. Mothers of 93 children with autism spectrum disorder completed an online survey regarding the severity of their own child's autism spectrum disorder (Social Communication Questionnaire), their child's behaviour problems (Strengths and Difficulties Questionnaire) and their own levels of parenting stress (Questionnaire on Resources and Stress). They were shown five videos of other parents interacting with children with autism spectrum disorder and were asked to rate the limit-setting abilities observed in each video using the Parent-Child Relationship Inventory. Higher parenting stress negatively related to judgements about others' limit-setting skills. This mirrors the literature regarding the relationship between self-reported parenting stress and rating child behaviour more negatively. It suggests that stress negatively impacts a wide range of judgements and implies that caution may be required when interpreting the results of studies in which parenting skills are assessed by self-report.

Scope of physician procedures independently billed by mid-level providers in the office setting.

Science.gov (United States)

Coldiron, Brett; Ratnarathorn, Mondhipa

2014-11-01

Mid-level providers (nurse practitioners and physician assistants) were originally envisioned to provide primary care services in underserved areas. This study details the current scope of independent procedural billing to Medicare of difficult, invasive, and surgical procedures by medical mid-level providers. To understand the scope of independent billing to Medicare for procedures performed by mid-level providers in an outpatient office setting for a calendar year. Analyses of the 2012 Medicare Physician/Supplier Procedure Summary Master File, which reflects fee-for-service claims that were paid by Medicare, for Current Procedural Terminology procedures independently billed by mid-level providers. Outpatient office setting among health care providers. The scope of independent billing to Medicare for procedures performed by mid-level providers. In 2012, nurse practitioners and physician assistants billed independently for more than 4 million procedures at our cutoff of 5000 paid claims per procedure. Most (54.8%) of these procedures were performed in the specialty area of dermatology. The findings of this study are relevant to safety and quality of care. Recently, the shortage of primary care clinicians has prompted discussion of widening the scope of practice for mid-level providers. It would be prudent to temper widening the scope of practice of mid-level providers by recognizing that mid-level providers are not solely limited to primary care, and may involve procedures for which they may not have formal training.

Abstract sets and finite ordinals an introduction to the study of set theory

CERN Document Server

Keene, G B

2007-01-01

This text unites the logical and philosophical aspects of set theory in a manner intelligible both to mathematicians without training in formal logic and to logicians without a mathematical background. It combines an elementary level of treatment with the highest possible degree of logical rigor and precision.Starting with an explanation of all the basic logical terms and related operations, the text progresses through a stage-by-stage elaboration that proves the fundamental theorems of finite sets. It focuses on the Bernays theory of finite classes and finite sets, exploring the system's basi

Heat transfer calculations for the High Flux Isotope Reactor (HFIR). Technical specifications: bases for safety limits and limiting safety system settings

International Nuclear Information System (INIS)

Sims, T.M.; Swanks, J.H.

1977-09-01

Heat transfer analyses, in support of the preparation of the HFIR technical specifications, were made to establish the bases for the safety limits and limiting safety system settings applicable to the HFIR. The results of these analyses, along with the detailed bases, are presented

HEDIS Limited Data Set

Data.gov (United States)

U.S. Department of Health & Human Services — The Healthcare Effectiveness Data and Information Set (HEDIS) is a tool used by more than 90 percent of Americas health plans to measure performance on important...

A limit set trichotomy for order-preserving systems on time scales

Directory of Open Access Journals (Sweden)

Christian Poetzsche

2004-04-01

Full Text Available In this paper we derive a limit set trichotomy for abstract order-preserving 2-parameter semiflows in normal cones of strongly ordered Banach spaces. Additionally, to provide an example, Muller's theorem is generalized to dynamic equations on arbitrary time scales and applied to a model from population dynamics.

GPU accelerated edge-region based level set evolution constrained by 2D gray-scale histogram.

Science.gov (United States)

Balla-Arabé, Souleymane; Gao, Xinbo; Wang, Bin

2013-07-01

Due to its intrinsic nature which allows to easily handle complex shapes and topological changes, the level set method (LSM) has been widely used in image segmentation. Nevertheless, LSM is computationally expensive, which limits its applications in real-time systems. For this purpose, we propose a new level set algorithm, which uses simultaneously edge, region, and 2D histogram information in order to efficiently segment objects of interest in a given scene. The computational complexity of the proposed LSM is greatly reduced by using the highly parallelizable lattice Boltzmann method (LBM) with a body force to solve the level set equation (LSE). The body force is the link with image data and is defined from the proposed LSE. The proposed LSM is then implemented using an NVIDIA graphics processing units to fully take advantage of the LBM local nature. The new algorithm is effective, robust against noise, independent to the initial contour, fast, and highly parallelizable. The edge and region information enable to detect objects with and without edges, and the 2D histogram information enable the effectiveness of the method in a noisy environment. Experimental results on synthetic and real images demonstrate subjectively and objectively the performance of the proposed method.

Technical basis for staffing levels at nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Shurberg, D.A.; Haber, S.B. [Brookhaven National Lab., Upton, NY (United States); Morisseau, D. [Nuclear Regulatory Commission, Washington, DC (United States)] [and others

1995-04-01

The objective of this project is to provide a technical basis for the establishment of criteria for minimum staffing levels of licensed and non-licensed NPP shift personnel. Minimum staffing levels for the purpose of this study, are defined as those necessary for successful accomplishment of all safety and additional functions that must be performed in order for the licensee to meet applicable regulatory requirements. This project involves a multi-faceted approach to the investigation of the issue. Relevant NRC documentation was identified and reviewed. Using the information obtained from this documentation review, a test plan was developed to aid in the collection of further information regarding the adequacy of current shift staffing levels. The test plan addresses three different activities to be conducted to provide information to the NRC for use in the assessment of current minimum staffing levels. The first activity is collection of data related to industry shift staffing practices through site visits to seven nuclear power plants. The second activity is a simulator study, which will use licensed operator crews responding to a simulated event, under two different staffing levels. Finally, workload models will be constructed for both licensed and non-licensed personnel, using a priori knowledge of the simulator scenarios with data resulting from one of the staffing levels studied in the simulator, and the data collected from the site visits. The model will then be validated against the data obtained from the second staffing level studied in the simulator. The validated model can then be used to study the impact of changing staffing-related variables on the plant shift crew`s ability to effectively mitigate an event.

Dilution testing using rapid diagnostic tests in a HIV diagnostic algorithm: a novel alternative for confirmation testing in resource limited settings.

Science.gov (United States)

Shanks, Leslie; Siddiqui, M Ruby; Abebe, Almaz; Piriou, Erwan; Pearce, Neil; Ariti, Cono; Masiga, Johnson; Muluneh, Libsework; Wazome, Joseph; Ritmeijer, Koert; Klarkowski, Derryck

2015-05-14

Current WHO testing guidelines for resource limited settings diagnose HIV on the basis of screening tests without a confirmation test due to cost constraints. This leads to a potential risk of false positive HIV diagnosis. In this paper, we evaluate the dilution test, a novel method for confirmation testing, which is simple, rapid, and low cost. The principle of the dilution test is to alter the sensitivity of a rapid diagnostic test (RDT) by dilution of the sample, in order to screen out the cross reacting antibodies responsible for falsely positive RDT results. Participants were recruited from two testing centres in Ethiopia where a tiebreaker algorithm using 3 different RDTs in series is used to diagnose HIV. All samples positive on the initial screening RDT and every 10th negative sample underwent testing with the gold standard and dilution test. Dilution testing was performed using Determine™ rapid diagnostic test at 6 different dilutions. Results were compared to the gold standard of Western Blot; where Western Blot was indeterminate, PCR testing determined the final result. 2895 samples were recruited to the study. 247 were positive for a prevalence of 8.5 % (247/2895). A total of 495 samples underwent dilution testing. The RDT diagnostic algorithm misclassified 18 samples as positive. Dilution at the level of 1/160 was able to correctly identify all these 18 false positives, but at a cost of a single false negative result (sensitivity 99.6 %, 95 % CI 97.8-100; specificity 100 %, 95 % CI: 98.5-100). Concordance between the gold standard and the 1/160 dilution strength was 99.8 %. This study provides proof of concept for a new, low cost method of confirming HIV diagnosis in resource-limited settings. It has potential for use as a supplementary test in a confirmatory algorithm, whereby double positive RDT results undergo dilution testing, with positive results confirming HIV infection. Negative results require nucleic acid testing to rule out false

Reevaluation of steam generator level trip set point

Energy Technology Data Exchange (ETDEWEB)

Shim, Yoon Sub; Soh, Dong Sub; Kim, Sung Oh; Jung, Se Won; Sung, Kang Sik; Lee, Joon [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1994-06-01

The reactor trip by the low level of steam generator water accounts for a substantial portion of reactor scrams in a nuclear plant and the feasibility of modification of the steam generator water level trip system of YGN 1/2 was evaluated in this study. The study revealed removal of the reactor trip function from the SG water level trip system is not possible because of plant safety but relaxation of the trip set point by 9 % is feasible. The set point relaxation requires drilling of new holes for level measurement to operating steam generators. Characteristics of negative neutron flux rate trip and reactor trip were also reviewed as an additional work. Since the purpose of the trip system modification for reduction of a reactor scram frequency is not to satisfy legal requirements but to improve plant performance and the modification yields positive and negative aspects, the decision of actual modification needs to be made based on the results of this study and also the policy of a plant owner. 37 figs, 6 tabs, 14 refs. (Author).

Peptide dynamics by molecular dynamics simulation and diffusion theory method with improved basis sets

Energy Technology Data Exchange (ETDEWEB)

Hsu, Po Jen; Lai, S. K., E-mail: sklai@coll.phy.ncu.edu.tw [Complex Liquids Laboratory, Department of Physics, National Central University, Chungli 320, Taiwan and Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan (China); Rapallo, Arnaldo [Istituto per lo Studio delle Macromolecole (ISMAC) Consiglio Nazionale delle Ricerche (CNR), via E. Bassini 15, C.A.P 20133 Milano (Italy)

2014-03-14

Improved basis sets for the study of polymer dynamics by means of the diffusion theory, and tests on a melt of cis-1,4-polyisoprene decamers, and a toluene solution of a 71-mer syndiotactic trans-1,2-polypentadiene were presented recently [R. Gaspari and A. Rapallo, J. Chem. Phys. 128, 244109 (2008)]. The proposed hybrid basis approach (HBA) combined two techniques, the long time sorting procedure and the maximum correlation approximation. The HBA takes advantage of the strength of these two techniques, and its basis sets proved to be very effective and computationally convenient in describing both local and global dynamics in cases of flexible synthetic polymers where the repeating unit is a unique type of monomer. The question then arises if the same efficacy continues when the HBA is applied to polymers of different monomers, variable local stiffness along the chain and with longer persistence length, which have different local and global dynamical properties against the above-mentioned systems. Important examples of this kind of molecular chains are the proteins, so that a fragment of the protein transthyretin is chosen as the system of the present study. This peptide corresponds to a sequence that is structured in β-sheets of the protein and is located on the surface of the channel with thyroxin. The protein transthyretin forms amyloid fibrils in vivo, whereas the peptide fragment has been shown [C. P. Jaroniec, C. E. MacPhee, N. S. Astrof, C. M. Dobson, and R. G. Griffin, Proc. Natl. Acad. Sci. U.S.A. 99, 16748 (2002)] to form amyloid fibrils in vitro in extended β-sheet conformations. For these reasons the latter is given considerable attention in the literature and studied also as an isolated fragment in water solution where both experimental and theoretical efforts have indicated the propensity of the system to form β turns or α helices, but is otherwise predominantly unstructured. Differing from previous computational studies that employed implicit

Peptide dynamics by molecular dynamics simulation and diffusion theory method with improved basis sets

International Nuclear Information System (INIS)

Hsu, Po Jen; Lai, S. K.; Rapallo, Arnaldo

2014-01-01

Improved basis sets for the study of polymer dynamics by means of the diffusion theory, and tests on a melt of cis-1,4-polyisoprene decamers, and a toluene solution of a 71-mer syndiotactic trans-1,2-polypentadiene were presented recently [R. Gaspari and A. Rapallo, J. Chem. Phys. 128, 244109 (2008)]. The proposed hybrid basis approach (HBA) combined two techniques, the long time sorting procedure and the maximum correlation approximation. The HBA takes advantage of the strength of these two techniques, and its basis sets proved to be very effective and computationally convenient in describing both local and global dynamics in cases of flexible synthetic polymers where the repeating unit is a unique type of monomer. The question then arises if the same efficacy continues when the HBA is applied to polymers of different monomers, variable local stiffness along the chain and with longer persistence length, which have different local and global dynamical properties against the above-mentioned systems. Important examples of this kind of molecular chains are the proteins, so that a fragment of the protein transthyretin is chosen as the system of the present study. This peptide corresponds to a sequence that is structured in β-sheets of the protein and is located on the surface of the channel with thyroxin. The protein transthyretin forms amyloid fibrils in vivo, whereas the peptide fragment has been shown [C. P. Jaroniec, C. E. MacPhee, N. S. Astrof, C. M. Dobson, and R. G. Griffin, Proc. Natl. Acad. Sci. U.S.A. 99, 16748 (2002)] to form amyloid fibrils in vitro in extended β-sheet conformations. For these reasons the latter is given considerable attention in the literature and studied also as an isolated fragment in water solution where both experimental and theoretical efforts have indicated the propensity of the system to form β turns or α helices, but is otherwise predominantly unstructured. Differing from previous computational studies that employed implicit

Relaxation of functions of STO-3G and 6-31G* basis sets in the series of isoelectronic to LiF molecule

International Nuclear Information System (INIS)

Ermakov, A.I.; Belousov, V.V.

2007-01-01

Relaxation effect of functions of the basis sets (BS) STO-3G and 6-31G* on their equilibration in the series of isoelectron molecules: LiF, BeO, BN and C 2 is considered. Values of parameters (exponential factor of basis functions, orbital exponents of Gauss primitives and coefficients of their grouping) of basis functions in molecules are discovered using the criterion of minimum of energy by the unlimited Hartree-Fock method calculations (UHF) with the help of direct optimization of parameters: the simplex-method and Rosenbrock method. Certain schemes of optimization differing by the amount of varying parameters have been done. Interaction of basis functions parameters of concerned sets through medium values of the Gauss exponents is established. Effects of relaxation on the change of full energy and relative errors of the calculations of interatomic distances, normal oscillations frequencies, dissociation energy and other properties of molecules are considered. Change of full energy during the relaxation of basis functions (RBF) STO-3G and 6-31G* amounts 1100 and 80 kJ/mol correspondingly, and it is in need of the account during estimation of energetic characteristics, especially for systems with high-polar chemical bonds. The relaxation BS STO-3G practically in all considered cases improves description of molecular properties, whereas the relaxation BS 6-31G* lightly effects on its equilibration [ru

Numerical Aspects of Atomic Physics: Helium Basis Sets and Matrix Diagonalization

Science.gov (United States)

Jentschura, Ulrich; Noble, Jonathan

2014-03-01

We present a matrix diagonalization algorithm for complex symmetric matrices, which can be used in order to determine the resonance energies of auto-ionizing states of comparatively simple quantum many-body systems such as helium. The algorithm is based in multi-precision arithmetic and proceeds via a tridiagonalization of the complex symmetric (not necessarily Hermitian) input matrix using generalized Householder transformations. Example calculations involving so-called PT-symmetric quantum systems lead to reference values which pertain to the imaginary cubic perturbation (the imaginary cubic anharmonic oscillator). We then proceed to novel basis sets for the helium atom and present results for Bethe logarithms in hydrogen and helium, obtained using the enhanced numerical techniques. Some intricacies of ``canned'' algorithms such as those used in LAPACK will be discussed. Our algorithm, for complex symmetric matrices such as those describing cubic resonances after complex scaling, is faster than LAPACK's built-in routines, for specific classes of input matrices. It also offer flexibility in terms of the calculation of the so-called implicit shift, which is used in order to ``pivot'' the system toward the convergence to diagonal form. We conclude with a wider overview.

Gradient augmented level set method for phase change simulations

Science.gov (United States)

Anumolu, Lakshman; Trujillo, Mario F.

2018-01-01

A numerical method for the simulation of two-phase flow with phase change based on the Gradient-Augmented-Level-set (GALS) strategy is presented. Sharp capturing of the vaporization process is enabled by: i) identification of the vapor-liquid interface, Γ (t), at the subgrid level, ii) discontinuous treatment of thermal physical properties (except for μ), and iii) enforcement of mass, momentum, and energy jump conditions, where the gradients of the dependent variables are obtained at Γ (t) and are consistent with their analytical expression, i.e. no local averaging is applied. Treatment of the jump in velocity and pressure at Γ (t) is achieved using the Ghost Fluid Method. The solution of the energy equation employs the sub-grid knowledge of Γ (t) to discretize the temperature Laplacian using second-order one-sided differences, i.e. the numerical stencil completely resides within each respective phase. To carefully evaluate the benefits or disadvantages of the GALS approach, the standard level set method is implemented and compared against the GALS predictions. The results show the expected trend that interface identification and transport are predicted noticeably better with GALS over the standard level set. This benefit carries over to the prediction of the Laplacian and temperature gradients in the neighborhood of the interface, which are directly linked to the calculation of the vaporization rate. However, when combining the calculation of interface transport and reinitialization with two-phase momentum and energy, the benefits of GALS are to some extent neutralized, and the causes for this behavior are identified and analyzed. Overall the additional computational costs associated with GALS are almost the same as those using the standard level set technique.

Mapping topographic structure in white matter pathways with level set trees.

Directory of Open Access Journals (Sweden)

Brian P Kent

Full Text Available Fiber tractography on diffusion imaging data offers rich potential for describing white matter pathways in the human brain, but characterizing the spatial organization in these large and complex data sets remains a challenge. We show that level set trees--which provide a concise representation of the hierarchical mode structure of probability density functions--offer a statistically-principled framework for visualizing and analyzing topography in fiber streamlines. Using diffusion spectrum imaging data collected on neurologically healthy controls (N = 30, we mapped white matter pathways from the cortex into the striatum using a deterministic tractography algorithm that estimates fiber bundles as dimensionless streamlines. Level set trees were used for interactive exploration of patterns in the endpoint distributions of the mapped fiber pathways and an efficient segmentation of the pathways that had empirical accuracy comparable to standard nonparametric clustering techniques. We show that level set trees can also be generalized to model pseudo-density functions in order to analyze a broader array of data types, including entire fiber streamlines. Finally, resampling methods show the reliability of the level set tree as a descriptive measure of topographic structure, illustrating its potential as a statistical descriptor in brain imaging analysis. These results highlight the broad applicability of level set trees for visualizing and analyzing high-dimensional data like fiber tractography output.

The Technology Acceptance Model for Resource-Limited Settings (TAM-RLS): A Novel Framework for Mobile Health Interventions Targeted to Low-Literacy End-Users in Resource-Limited Settings.

Science.gov (United States)

Campbell, Jeffrey I; Aturinda, Isaac; Mwesigwa, Evans; Burns, Bridget; Santorino, Data; Haberer, Jessica E; Bangsberg, David R; Holden, Richard J; Ware, Norma C; Siedner, Mark J

2017-11-01

Although mobile health (mHealth) technologies have shown promise in improving clinical care in resource-limited settings (RLS), they are infrequently brought to scale. One limitation to the success of many mHealth interventions is inattention to end-user acceptability, which is an important predictor of technology adoption. We conducted in-depth interviews with 43 people living with HIV in rural Uganda who had participated in a clinical trial of a short messaging system (SMS)-based intervention designed to prompt return to clinic after an abnormal laboratory test. Interviews focused on established features of technology acceptance models, including perceived ease of use and perceived usefulness, and included open-ended questions to gain insight into unexplored issues related to the intervention's acceptability. We used conventional (inductive) and direct content analysis to derive categories describing use behaviors and acceptability. Interviews guided development of a proposed conceptual framework, the technology acceptance model for resource-limited settings (TAM-RLS). This framework incorporates both classic technology acceptance model categories as well as novel factors affecting use in this setting. Participants described how SMS message language, phone characteristics, and experience with similar technologies contributed to the system's ease of use. Perceived usefulness was shaped by the perception that the system led to augmented HIV care services and improved access to social support from family and colleagues. Emergent themes specifically related to mHealth acceptance among PLWH in Uganda included (1) the importance of confidentiality, disclosure, and stigma, and (2) the barriers and facilitators downstream from the intervention that impacted achievement of the system's target outcome. The TAM-RLS is a proposed model of mHealth technology acceptance based upon end-user experiences in rural Uganda. Although the proposed model requires validation, the TAM

A simple mass-conserved level set method for simulation of multiphase flows

Science.gov (United States)

Yuan, H.-Z.; Shu, C.; Wang, Y.; Shu, S.

2018-04-01

In this paper, a modified level set method is proposed for simulation of multiphase flows with large density ratio and high Reynolds number. The present method simply introduces a source or sink term into the level set equation to compensate the mass loss or offset the mass increase. The source or sink term is derived analytically by applying the mass conservation principle with the level set equation and the continuity equation of flow field. Since only a source term is introduced, the application of the present method is as simple as the original level set method, but it can guarantee the overall mass conservation. To validate the present method, the vortex flow problem is first considered. The simulation results are compared with those from the original level set method, which demonstrates that the modified level set method has the capability of accurately capturing the interface and keeping the mass conservation. Then, the proposed method is further validated by simulating the Laplace law, the merging of two bubbles, a bubble rising with high density ratio, and Rayleigh-Taylor instability with high Reynolds number. Numerical results show that the mass is a well-conserved by the present method.

Complexities of Providing Dental Hygiene Services in Community Care Settings.

Science.gov (United States)

Zarkowski, Pamela; Aksu, Mert N

2016-06-01

Direct access care provided by dental hygienists can reduce oral health disparities for the underserved, yet legal, regulatory, and ethical considerations create complexities and limits. Individual state dental practice acts regulate the scope of practice and level of supervision required when dental hygienists deliver care. Yet, inconsistent state practice act regulations contribute to ethical and legal limitations and dilemmas for practitioners. The dental hygienist is positioned to assume an increasingly larger role in the management of oral health disparities. However, there are several legal and ethical considerations that impact both dental hygienists and dentists providing care in complex community settings. This article informs dental hygienists and other related constituencies about conundrums that are encountered when providing care 'beyond the operatory.' An evidence-based view of ways in which dental hygienists are reducing oral health disparities illustrates the complex issues involved in providing such care. Potential scenarios that can occur during care provision in underserved settings provide the basis for a discussion of legal and other associated issues impacting dental hygiene practice. Copyright © 2016 Elsevier Inc. All rights reserved.

Reconstruction of thin electromagnetic inclusions by a level-set method

International Nuclear Information System (INIS)

Park, Won-Kwang; Lesselier, Dominique

2009-01-01

In this contribution, we consider a technique of electromagnetic imaging (at a single, non-zero frequency) which uses the level-set evolution method for reconstructing a thin inclusion (possibly made of disconnected parts) with either dielectric or magnetic contrast with respect to the embedding homogeneous medium. Emphasis is on the proof of the concept, the scattering problem at hand being so far based on a two-dimensional scalar model. To do so, two level-set functions are employed; the first one describes location and shape, and the other one describes connectivity and length. Speeds of evolution of the level-set functions are calculated via the introduction of Fréchet derivatives of a least-square cost functional. Several numerical experiments on noiseless and noisy data as well illustrate how the proposed method behaves

Level-Set Methodology on Adaptive Octree Grids

Science.gov (United States)

Gibou, Frederic; Guittet, Arthur; Mirzadeh, Mohammad; Theillard, Maxime

2017-11-01

Numerical simulations of interfacial problems in fluids require a methodology capable of tracking surfaces that can undergo changes in topology and capable to imposing jump boundary conditions in a sharp manner. In this talk, we will discuss recent advances in the level-set framework, in particular one that is based on adaptive grids.

Toward a W4-F12 approach: Can explicitly correlated and orbital-based ab initio CCSD(T) limits be reconciled?

Energy Technology Data Exchange (ETDEWEB)

Sylvetsky, Nitai, E-mail: gershom@weizmann.ac.il; Martin, Jan M. L., E-mail: gershom@weizmann.ac.il [Department of Organic Chemistry, Weizmann Institute of Science, 76100 Rehovot (Israel); Peterson, Kirk A., E-mail: kipeters@wsu.edu [Department of Chemistry, Washington State University, Pullman, Washington 99164-4630 (United States); Karton, Amir, E-mail: amir.karton@uwa.edu.au [School of Chemistry and Biochemistry, The University of Western Australia, Perth, WA 6009 (Australia)

2016-06-07

In the context of high-accuracy computational thermochemistry, the valence coupled cluster with all singles and doubles (CCSD) correlation component of molecular atomization energies presents the most severe basis set convergence problem, followed by the (T) component. In the present paper, we make a detailed comparison, for an expanded version of the W4-11 thermochemistry benchmark, between, on the one hand, orbital-based CCSD/AV{5,6}Z + d and CCSD/ACV{5,6}Z extrapolation, and on the other hand CCSD-F12b calculations with cc-pVQZ-F12 and cc-pV5Z-F12 basis sets. This latter basis set, now available for H–He, B–Ne, and Al–Ar, is shown to be very close to the basis set limit. Apparent differences (which can reach 0.35 kcal/mol for systems like CCl{sub 4}) between orbital-based and CCSD-F12b basis set limits disappear if basis sets with additional radial flexibility, such as ACV{5,6}Z, are used for the orbital calculation. Counterpoise calculations reveal that, while total atomization energies with V5Z-F12 basis sets are nearly free of BSSE, orbital calculations have significant BSSE even with AV(6 + d)Z basis sets, leading to non-negligible differences between raw and counterpoise-corrected extrapolated limits. This latter problem is greatly reduced by switching to ACV{5,6}Z core-valence basis sets, or simply adding an additional zeta to just the valence orbitals. Previous reports that all-electron approaches like HEAT (high-accuracy extrapolated ab-initio thermochemistry) lead to different CCSD(T) limits than “valence limit + CV correction” approaches like Feller-Peterson-Dixon and Weizmann-4 (W4) theory can be rationalized in terms of the greater radial flexibility of core-valence basis sets. For (T) corrections, conventional CCSD(T)/AV{Q,5}Z + d calculations are found to be superior to scaled or extrapolated CCSD(T)-F12b calculations of similar cost. For a W4-F12 protocol, we recommend obtaining the Hartree-Fock and valence CCSD components from CCSD-F12b

Fundamental energy limits of SET-based Brownian NAND and half-adder circuits. Preliminary findings from a physical-information-theoretic methodology

Science.gov (United States)

Ercan, İlke; Suyabatmaz, Enes

2018-06-01

The saturation in the efficiency and performance scaling of conventional electronic technologies brings about the development of novel computational paradigms. Brownian circuits are among the promising alternatives that can exploit fluctuations to increase the efficiency of information processing in nanocomputing. A Brownian cellular automaton, where signals propagate randomly and are driven by local transition rules, can be made computationally universal by embedding arbitrary asynchronous circuits on it. One of the potential realizations of such circuits is via single electron tunneling (SET) devices since SET technology enable simulation of noise and fluctuations in a fashion similar to Brownian search. In this paper, we perform a physical-information-theoretic analysis on the efficiency limitations in a Brownian NAND and half-adder circuits implemented using SET technology. The method we employed here establishes a solid ground that enables studying computational and physical features of this emerging technology on an equal footing, and yield fundamental lower bounds that provide valuable insights into how far its efficiency can be improved in principle. In order to provide a basis for comparison, we also analyze a NAND gate and half-adder circuit implemented in complementary metal oxide semiconductor technology to show how the fundamental bound of the Brownian circuit compares against a conventional paradigm.

An accurate conservative level set/ghost fluid method for simulating turbulent atomization

International Nuclear Information System (INIS)

Desjardins, Olivier; Moureau, Vincent; Pitsch, Heinz

2008-01-01

This paper presents a novel methodology for simulating incompressible two-phase flows by combining an improved version of the conservative level set technique introduced in [E. Olsson, G. Kreiss, A conservative level set method for two phase flow, J. Comput. Phys. 210 (2005) 225-246] with a ghost fluid approach. By employing a hyperbolic tangent level set function that is transported and re-initialized using fully conservative numerical schemes, mass conservation issues that are known to affect level set methods are greatly reduced. In order to improve the accuracy of the conservative level set method, high order numerical schemes are used. The overall robustness of the numerical approach is increased by computing the interface normals from a signed distance function reconstructed from the hyperbolic tangent level set by a fast marching method. The convergence of the curvature calculation is ensured by using a least squares reconstruction. The ghost fluid technique provides a way of handling the interfacial forces and large density jumps associated with two-phase flows with good accuracy, while avoiding artificial spreading of the interface. Since the proposed approach relies on partial differential equations, its implementation is straightforward in all coordinate systems, and it benefits from high parallel efficiency. The robustness and efficiency of the approach is further improved by using implicit schemes for the interface transport and re-initialization equations, as well as for the momentum solver. The performance of the method is assessed through both classical level set transport tests and simple two-phase flow examples including topology changes. It is then applied to simulate turbulent atomization of a liquid Diesel jet at Re=3000. The conservation errors associated with the accurate conservative level set technique are shown to remain small even for this complex case

Transport and diffusion of material quantities on propagating interfaces via level set methods

CERN Document Server

Adalsteinsson, D

2003-01-01

We develop theory and numerical algorithms to apply level set methods to problems involving the transport and diffusion of material quantities in a level set framework. Level set methods are computational techniques for tracking moving interfaces; they work by embedding the propagating interface as the zero level set of a higher dimensional function, and then approximate the solution of the resulting initial value partial differential equation using upwind finite difference schemes. The traditional level set method works in the trace space of the evolving interface, and hence disregards any parameterization in the interface description. Consequently, material quantities on the interface which themselves are transported under the interface motion are not easily handled in this framework. We develop model equations and algorithmic techniques to extend the level set method to include these problems. We demonstrate the accuracy of our approach through a series of test examples and convergence studies.

Transport and diffusion of material quantities on propagating interfaces via level set methods

International Nuclear Information System (INIS)

Adalsteinsson, David; Sethian, J.A.

2003-01-01

We develop theory and numerical algorithms to apply level set methods to problems involving the transport and diffusion of material quantities in a level set framework. Level set methods are computational techniques for tracking moving interfaces; they work by embedding the propagating interface as the zero level set of a higher dimensional function, and then approximate the solution of the resulting initial value partial differential equation using upwind finite difference schemes. The traditional level set method works in the trace space of the evolving interface, and hence disregards any parameterization in the interface description. Consequently, material quantities on the interface which themselves are transported under the interface motion are not easily handled in this framework. We develop model equations and algorithmic techniques to extend the level set method to include these problems. We demonstrate the accuracy of our approach through a series of test examples and convergence studies

Simulations of smog-chamber experiments using the two-dimensional volatility basis set: linear oxygenated precursors.

Science.gov (United States)

Chacon-Madrid, Heber J; Murphy, Benjamin N; Pandis, Spyros N; Donahue, Neil M

2012-10-16

We use a two-dimensional volatility basis set (2D-VBS) box model to simulate secondary organic aerosol (SOA) mass yields of linear oxygenated molecules: n-tridecanal, 2- and 7-tridecanone, 2- and 7-tridecanol, and n-pentadecane. A hybrid model with explicit, a priori treatment of the first-generation products for each precursor molecule, followed by a generic 2D-VBS mechanism for later-generation chemistry, results in excellent model-measurement agreement. This strongly confirms that the 2D-VBS mechanism is a predictive tool for SOA modeling but also suggests that certain important first-generation products for major primary SOA precursors should be treated explicitly for optimal SOA predictions.

A level set approach for shock-induced α-γ phase transition of RDX

Science.gov (United States)

Josyula, Kartik; Rahul; De, Suvranu

2018-02-01

We present a thermodynamically consistent level sets approach based on regularization energy functional which can be directly incorporated into a Galerkin finite element framework to model interface motion. The regularization energy leads to a diffusive form of flux that is embedded within the level sets evolution equation which maintains the signed distance property of the level set function. The scheme is shown to compare well with the velocity extension method in capturing the interface position. The proposed level sets approach is employed to study the α-γphase transformation in RDX single crystal shocked along the (100) plane. Example problems in one and three dimensions are presented. We observe smooth evolution of the phase interface along the shock direction in both models. There is no diffusion of the interface during the zero level set evolution in the three dimensional model. The level sets approach is shown to capture the characteristics of the shock-induced α-γ phase transformation such as stress relaxation behind the phase interface and the finite time required for the phase transformation to complete. The regularization energy based level sets approach is efficient, robust, and easy to implement.

Level Set Approach to Anisotropic Wet Etching of Silicon

Directory of Open Access Journals (Sweden)

Branislav Radjenović

2010-05-01

Full Text Available In this paper a methodology for the three dimensional (3D modeling and simulation of the profile evolution during anisotropic wet etching of silicon based on the level set method is presented. Etching rate anisotropy in silicon is modeled taking into account full silicon symmetry properties, by means of the interpolation technique using experimentally obtained values for the etching rates along thirteen principal and high index directions in KOH solutions. The resulting level set equations are solved using an open source implementation of the sparse field method (ITK library, developed in medical image processing community, extended for the case of non-convex Hamiltonians. Simulation results for some interesting initial 3D shapes, as well as some more practical examples illustrating anisotropic etching simulation in the presence of masks (simple square aperture mask, convex corner undercutting and convex corner compensation, formation of suspended structures are shown also. The obtained results show that level set method can be used as an effective tool for wet etching process modeling, and that is a viable alternative to the Cellular Automata method which now prevails in the simulations of the wet etching process.

INTEGRATED SFM TECHNIQUES USING DATA SET FROM GOOGLE EARTH 3D MODEL AND FROM STREET LEVEL

Directory of Open Access Journals (Sweden)

L. Inzerillo

2017-08-01

Full Text Available Structure from motion (SfM represents a widespread photogrammetric method that uses the photogrammetric rules to carry out a 3D model from a photo data set collection. Some complex ancient buildings, such as Cathedrals, or Theatres, or Castles, etc. need to implement the data set (realized from street level with the UAV one in order to have the 3D roof reconstruction. Nevertheless, the use of UAV is strong limited from the government rules. In these last years, Google Earth (GE has been enriched with the 3D models of the earth sites. For this reason, it seemed convenient to start to test the potentiality offered by GE in order to extract from it a data set that replace the UAV function, to close the aerial building data set, using screen images of high resolution 3D models. Users can take unlimited “aerial photos” of a scene while flying around in GE at any viewing angle and altitude. The challenge is to verify the metric reliability of the SfM model carried out with an integrated data set (the one from street level and the one from GE aimed at replace the UAV use in urban contest. This model is called integrated GE SfM model (i-GESfM. In this paper will be present a case study: the Cathedral of Palermo.

Technical basis for high-level waste repository land control requirements for Palo Duro Basin, Paradox Basin, and Richton Dome

International Nuclear Information System (INIS)

Chen, C.P.; Raines, G.E.

1987-02-01

Three sites, the Palo Duro Basin in Texas, the Paradox Basin in Utah, and the Richton Dome in Mississippi, are being investigated by the US Department of Energy for high-level radioactive-waste disposal in mined, deep geologic repositories in salt. This report delineates the use of regulatory, engineering, and performance assessment information to establish the technical basis for controlled area requirements. Based on the size of the controlled area determined, plus that of the geologic repository operations area, recommendations of possible land control or ownership area requirements for each locale are provided. On a technical basis, the following minimum land control or ownership requirements are recommended, assuming repository operations area of 2240 ac (907 ha), or 3.5 mi 2 (9.1 km 2 ): Palo Duro Basin - 4060 ac (1643 ha), or 6.3 mi 2 (16.4 km 2 ); Paradox Basin - 4060 ac (1643 ha), or 6.3 mi 2 (16.4 km 2 ); and Richton Dome - 5000 ac (2024 ha), or 7.8 mi 2 (20.2 km 2 ). Of the factors used to determine the technically based recommendations, one was found to dominate each locale. For the Palo Duro and Paradox Basins, the dominant factor was the need to limit potential radionuclide release by ground-water flow to the accessible environment. For the Richton Dome, the dominant factor was the need to limit the potential effects of solution mining on dome and repository integrity

Two Surface-Tension Formulations For The Level Set Interface-Tracking Method

International Nuclear Information System (INIS)

Shepel, S.V.; Smith, B.L.

2005-01-01

The paper describes a comparative study of two surface-tension models for the Level Set interface tracking method. In both models, the surface tension is represented as a body force, concentrated near the interface, but the technical implementation of the two options is different. The first is based on a traditional Level Set approach, in which the surface tension is distributed over a narrow band around the interface using a smoothed Delta function. In the second model, which is based on the integral form of the fluid-flow equations, the force is imposed only in those computational cells through which the interface passes. Both models have been incorporated into the Finite-Element/Finite-Volume Level Set method, previously implemented into the commercial Computational Fluid Dynamics (CFD) code CFX-4. A critical evaluation of the two models, undertaken in the context of four standard Level Set benchmark problems, shows that the first model, based on the smoothed Delta function approach, is the more general, and more robust, of the two. (author)

Establishing Medical Schools in Limited Resource Settings.

Science.gov (United States)

Tsinuel, Girma; Tsedeke, Asaminew; Matthias, Siebeck; Fischer, Martin R; Jacobs, Fabian; Sebsibe, Desalegn; Yoseph, Mamo; Abraham, Haileamlak

2016-05-01

One urgent goal of countries in sub-Saharan Africa is to dynamically scale up the education and work force of medical doctors in the training institutions and health facilities, respectively. These countries face challenges related to the rapid scale up which is mostly done without proper strategic planning, without the basic elements of infrastructure development, educational as well as academic and administrative human resources. Medical education done in the context of limited resources is thus compromising the quality of graduates. In the future, a collaborative and need-based approach involving major stakeholders such as medical educators concerned, ministries, planners and policy makers is needed. This article identifies the challenges of establishing medical schools and sustaining the quality of education through rapid scale-up in Sub-Saharan Africa in the settings of limited resources. It also outlines the minimum requirements for establishing medical schools. A consensus building workshop was conducted in Bishoftu, Ethiopia, from Nov 8-12, 2013. Participants were professionals from 13 Ethiopian medical schools, and representatives of medical schools from South Sudan, Somaliland, Somalia, and Mozambique. Participants are listed in Appendix 1. The governments and stakeholders should jointly develop strategic plans and a roadmaps for opening or expanding medical schools to scale up educational resources. It is advisable that medical schools have autonomy regarding the number of student-intake, student selection, curriculum ownership, resource allocation including for infrastructure and staff development. Health science and medical curricula should be integrated within and harmonized nationally. An educational evaluation framework needs to be embedded in the curricula, and all medical schools should have Health Science Education Development Centers.

A deep level set method for image segmentation

OpenAIRE

Tang, Min; Valipour, Sepehr; Zhang, Zichen Vincent; Cobzas, Dana; MartinJagersand

2017-01-01

This paper proposes a novel image segmentation approachthat integrates fully convolutional networks (FCNs) with a level setmodel. Compared with a FCN, the integrated method can incorporatesmoothing and prior information to achieve an accurate segmentation.Furthermore, different than using the level set model as a post-processingtool, we integrate it into the training phase to fine-tune the FCN. Thisallows the use of unlabeled data during training in a semi-supervisedsetting. Using two types o...

A LEVEL SET BASED SHAPE OPTIMIZATION METHOD FOR AN ELLIPTIC OBSTACLE PROBLEM

KAUST Repository

Burger, Martin

2011-04-01

In this paper, we construct a level set method for an elliptic obstacle problem, which can be reformulated as a shape optimization problem. We provide a detailed shape sensitivity analysis for this reformulation and a stability result for the shape Hessian at the optimal shape. Using the shape sensitivities, we construct a geometric gradient flow, which can be realized in the context of level set methods. We prove the convergence of the gradient flow to an optimal shape and provide a complete analysis of the level set method in terms of viscosity solutions. To our knowledge this is the first complete analysis of a level set method for a nonlocal shape optimization problem. Finally, we discuss the implementation of the methods and illustrate its behavior through several computational experiments. © 2011 World Scientific Publishing Company.

Gene set analysis: limitations in popular existing methods and proposed improvements.

Science.gov (United States)

Mishra, Pashupati; Törönen, Petri; Leino, Yrjö; Holm, Liisa

2014-10-01

Gene set analysis is the analysis of a set of genes that collectively contribute to a biological process. Most popular gene set analysis methods are based on empirical P-value that requires large number of permutations. Despite numerous gene set analysis methods developed in the past decade, the most popular methods still suffer from serious limitations. We present a gene set analysis method (mGSZ) based on Gene Set Z-scoring function (GSZ) and asymptotic P-values. Asymptotic P-value calculation requires fewer permutations, and thus speeds up the gene set analysis process. We compare the GSZ-scoring function with seven popular gene set scoring functions and show that GSZ stands out as the best scoring function. In addition, we show improved performance of the GSA method when the max-mean statistics is replaced by the GSZ scoring function. We demonstrate the importance of both gene and sample permutations by showing the consequences in the absence of one or the other. A comparison of asymptotic and empirical methods of P-value estimation demonstrates a clear advantage of asymptotic P-value over empirical P-value. We show that mGSZ outperforms the state-of-the-art methods based on two different evaluations. We compared mGSZ results with permutation and rotation tests and show that rotation does not improve our asymptotic P-values. We also propose well-known asymptotic distribution models for three of the compared methods. mGSZ is available as R package from cran.r-project.org. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

The NANOGrav Nine-year Data Set: Limits on the Isotropic Stochastic Gravitational Wave Background

OpenAIRE

Arzoumanian, Zaven; Brazier, Adam; Burke-Spolaor, Sarah; Chamberlin, Sydney; Chatterjee, Shami; Christy, Brian; Cordes, Jim; Cornish, Neil; Demorest, Paul; Deng, Xihao; Dolch, Tim; Ellis, Justin; Ferdman, Rob; Fonseca, Emmanuel; Garver-Daniels, Nate

2015-01-01

We compute upper limits on the nanohertz-frequency isotropic stochastic gravitational wave background (GWB) using the 9-year data release from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration. We set upper limits for a GWB from supermassive black hole binaries under power law, broken power law, and free spectral coefficient GW spectrum models. We place a 95\\% upper limit on the strain amplitude (at a frequency of yr$^{-1}$) in the power law model of $A...

Approaches for the development of occupational exposure limits for man-made mineral fibres (MMMFs)

International Nuclear Information System (INIS)

Ziegler-Skylakakis, Kyriakoula

2004-01-01

Occupational exposure limits (OELs) are an essential tool in the control of exposure to hazardous chemical agents, and serve to minimise the occurrence of occupational diseases associated with such exposure. The setting of OELs, together with other associated measures, forms an essential part of the European Community's strategy on health and safety at work, upon which the legislative framework for the protection of workers from risks related to chemical agents is based. The European Commission is assisted by the Scientific Committee on Occupational Exposure Limits (SCOEL) in its work of setting OELs for hazardous chemical agents. The procedure for setting OELs requires information on the toxic mechanisms of an agent that should allow to differentiate between thresholded and non-thresholded mechanisms. In the first case, a no-observed adverse effect level (NOAEL) can be defined, which can be the basis for a derivation of an OEL. In the latter case, any exposure is correlated with a certain risk. If adequate scientific data are available, SCOEL estimates the risk associated with a series of exposure levels. This can then be used for guidance, when setting OELs at European level. Man-made mineral fibres (MMMFs) are widely used at different worksites. MMMF products can release airborne respirable fibres during their production, use and removal. According to the classification of the EU system, all MMMF fibres are considered to be irritants and are classified for carcinogenicity. EU legislation foresees the use of limit values as one of the provisions for the protection of workers from the risks related to exposure to carcinogens. In the following paper, the research requirements identified by SCOEL for the development of OELs for MMMFs will be presented

Adjusting Limit Setting in Play Therapy with First-Generation Mexican-American Children

Science.gov (United States)

Perez, Roxanna; Ramirez, Sylvia Z.; Kranz, Peter L.

2007-01-01

This paper focuses on limit setting in play therapy with first-generation Mexican-American children in two important therapeutic environments that include the traditional indoor playroom and a proposed outdoor play area. The paper is based on a review of the literature and the authors' clinical experiences with this population. They concluded…

Experiencing a probabilistic approach to clarify and disclose uncertainties when setting occupational exposure limits.

Science.gov (United States)

Vernez, David; Fraize-Frontier, Sandrine; Vincent, Raymond; Binet, Stéphane; Rousselle, Christophe

2018-03-15

Assessment factors (AFs) are commonly used for deriving reference concentrations for chemicals. These factors take into account variabilities as well as uncertainties in the dataset, such as inter-species and intra-species variabilities or exposure duration extrapolation or extrapolation from the lowest-observed-adverse-effect level (LOAEL) to the noobserved- adverse-effect level (NOAEL). In a deterministic approach, the value of an AF is the result of a debate among experts and, often a conservative value is used as a default choice. A probabilistic framework to better take into account uncertainties and/or variability when setting occupational exposure limits (OELs) is presented and discussed in this paper. Each AF is considered as a random variable with a probabilistic distribution. A short literature was conducted before setting default distributions ranges and shapes for each AF commonly used. A random sampling, using Monte Carlo techniques, is then used for propagating the identified uncertainties and computing the final OEL distribution. Starting from the broad default distributions obtained, experts narrow it to its most likely range, according to the scientific knowledge available for a specific chemical. Introducing distribution rather than single deterministic values allows disclosing and clarifying variability and/or uncertainties inherent to the OEL construction process. This probabilistic approach yields quantitative insight into both the possible range and the relative likelihood of values for model outputs. It thereby provides a better support in decision-making and improves transparency. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Improving Limit Surface Search Algorithms in RAVEN Using Acceleration Schemes: Level II Milestone

Energy Technology Data Exchange (ETDEWEB)

Alfonsi, Andrea [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Rabiti, Cristian [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Cogliati, Joshua Joseph [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Sen, Ramazan Sonat [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Smith, Curtis Lee [Idaho National Laboratory (INL), Idaho Falls, ID (United States)

2015-07-01

The RAVEN code is becoming a comprehensive tool to perform Probabilistic Risk Assessment (PRA); Uncertainty Quantification (UQ) and Propagation; and Verification and Validation (V&V). The RAVEN code is being developed to support the Risk-Informed Safety Margin Characterization (RISMC) pathway by developing an advanced set of methodologies and algorithms for use in advanced risk analysis. The RISMC approach uses system simulator codes applied to stochastic analysis tools. The fundamental idea behind this coupling approach to perturb (by employing sampling strategies) timing and sequencing of events, internal parameters of the system codes (i.e., uncertain parameters of the physics model) and initial conditions to estimate values ranges and associated probabilities of figures of merit of interest for engineering and safety (e.g. core damage probability, etc.). This approach applied to complex systems such as nuclear power plants requires performing a series of computationally expensive simulation runs. The large computational burden is caused by the large set of (uncertain) parameters characterizing those systems. Consequently, exploring the uncertain/parametric domain, with a good level of confidence, is generally not affordable, considering the limited computational resources that are currently available. In addition, the recent tendency to develop newer tools, characterized by higher accuracy and larger computational resources (if compared with the presently used legacy codes, that have been developed decades ago), has made this issue even more compelling. In order to overcome to these limitations, the strategy for the exploration of the uncertain/parametric space needs to use at best the computational resources focusing the computational effort in those regions of the uncertain/parametric space that are “interesting” (e.g., risk-significant regions of the input space) with respect the targeted Figures Of Merit (FOM): for example, the failure of the system

Refined energetic ordering for sulphate-water (n = 3-6) clusters using high-level electronic structure calculations

Science.gov (United States)

Lambrecht, Daniel S.; McCaslin, Laura; Xantheas, Sotiris S.; Epifanovsky, Evgeny; Head-Gordon, Martin

2012-10-01

This work reports refinements of the energetic ordering of the known low-energy structures of sulphate-water clusters ? (n = 3-6) using high-level electronic structure methods. Coupled cluster singles and doubles with perturbative triples (CCSD(T)) is used in combination with an estimate of basis set effects up to the complete basis set limit using second-order Møller-Plesset theory. Harmonic zero-point energy (ZPE), included at the B3LYP/6-311 + + G(3df,3pd) level, was found to have a significant effect on the energetic ordering. In fact, we show that the energetic ordering is a result of a delicate balance between the electronic and vibrational energies. Limitations of the ZPE calculations, both due to electronic structure errors, and use of the harmonic approximation, probably constitute the largest remaining errors. Due to the often small energy differences between cluster isomers, and the significant role of ZPE, deuteration can alter the relative energies of low-lying structures, and, when it is applied in conjunction with calculated harmonic ZPEs, even alters the global minimum for n = 5. Experiments on deuterated clusters, as well as more sophisticated vibrational calculations, may therefore be quite interesting.

Electronic structure of crystalline uranium nitrides UN, U2N3 and UN2: LCAO calculations with the basis set optimization

International Nuclear Information System (INIS)

Evarestov, R A; Panin, A I; Bandura, A V; Losev, M V

2008-01-01

The results of LCAO DFT calculations of lattice parameters, cohesive energy and bulk modulus of the crystalline uranium nitrides UN, U 2 N 3 and UN 2 are presented and discussed. The LCAO computer codes Gaussian03 and Crystal06 are applied. The calculations are made with the uranium atom relativistic effective small core potential by Stuttgart-Cologne group (60 electrons in the core). The calculations include the U atom basis set optimization. Powell, Hooke-Jeeves, conjugated gradient and Box methods are implemented in the author's optimization package, being external to the codes for molecular and periodic calculations. The basis set optimization in LCAO calculations improves the agreement of the lattice parameter and bulk modulus of UN crystal with the experimental data, the change of the cohesive energy due to the optimization is small. The mixed metallic-covalent chemical bonding is found both in LCAO calculations of UN and U 2 N 3 crystals; UN 2 crystal has the semiconducting nature

A LEVEL SET BASED SHAPE OPTIMIZATION METHOD FOR AN ELLIPTIC OBSTACLE PROBLEM

KAUST Repository

Burger, Martin; Matevosyan, Norayr; Wolfram, Marie-Therese

2011-01-01

analysis of the level set method in terms of viscosity solutions. To our knowledge this is the first complete analysis of a level set method for a nonlocal shape optimization problem. Finally, we discuss the implementation of the methods and illustrate its

Calculations of wavefunctions and energies of electron system in Coulomb potential by variational method without a basis set

International Nuclear Information System (INIS)

Bykov, V.P.; Gerasimov, A.V.

1992-08-01

A new variational method without a basis set for calculation of the eigenvalues and eigenfunctions of Hamiltonians is suggested. The expansion of this method for the Coulomb potentials is given. Calculation of the energy and charge distribution in the two-electron system for different values of the nuclear charge Z is made. It is shown that at small Z the Coulomb forces disintegrate the electron cloud into two clots. (author). 3 refs, 4 figs, 1 tab

The use of an integrated variable fuzzy sets in water resources management

Science.gov (United States)

Qiu, Qingtai; Liu, Jia; Li, Chuanzhe; Yu, Xinzhe; Wang, Yang

2018-06-01

Based on the evaluation of the present situation of water resources and the development of water conservancy projects and social economy, optimal allocation of regional water resources presents an increasing need in the water resources management. Meanwhile it is also the most effective way to promote the harmonic relationship between human and water. In view of the own limitations of the traditional evaluations of which always choose a single index model using in optimal allocation of regional water resources, on the basis of the theory of variable fuzzy sets (VFS) and system dynamics (SD), an integrated variable fuzzy sets model (IVFS) is proposed to address dynamically complex problems in regional water resources management in this paper. The model is applied to evaluate the level of the optimal allocation of regional water resources of Zoucheng in China. Results show that the level of allocation schemes of water resources ranging from 2.5 to 3.5, generally showing a trend of lower level. To achieve optimal regional management of water resources, this model conveys a certain degree of accessing water resources management, which prominently improve the authentic assessment of water resources management by using the eigenvector of level H.

A local level set method based on a finite element method for unstructured meshes

International Nuclear Information System (INIS)

Ngo, Long Cu; Choi, Hyoung Gwon

2016-01-01

A local level set method for unstructured meshes has been implemented by using a finite element method. A least-square weighted residual method was employed for implicit discretization to solve the level set advection equation. By contrast, a direct re-initialization method, which is directly applicable to the local level set method for unstructured meshes, was adopted to re-correct the level set function to become a signed distance function after advection. The proposed algorithm was constructed such that the advection and direct reinitialization steps were conducted only for nodes inside the narrow band around the interface. Therefore, in the advection step, the Gauss–Seidel method was used to update the level set function using a node-by-node solution method. Some benchmark problems were solved by using the present local level set method. Numerical results have shown that the proposed algorithm is accurate and efficient in terms of computational time

A local level set method based on a finite element method for unstructured meshes

Energy Technology Data Exchange (ETDEWEB)

Ngo, Long Cu; Choi, Hyoung Gwon [School of Mechanical Engineering, Seoul National University of Science and Technology, Seoul (Korea, Republic of)

2016-12-15

A local level set method for unstructured meshes has been implemented by using a finite element method. A least-square weighted residual method was employed for implicit discretization to solve the level set advection equation. By contrast, a direct re-initialization method, which is directly applicable to the local level set method for unstructured meshes, was adopted to re-correct the level set function to become a signed distance function after advection. The proposed algorithm was constructed such that the advection and direct reinitialization steps were conducted only for nodes inside the narrow band around the interface. Therefore, in the advection step, the Gauss–Seidel method was used to update the level set function using a node-by-node solution method. Some benchmark problems were solved by using the present local level set method. Numerical results have shown that the proposed algorithm is accurate and efficient in terms of computational time.

Setting clear expectations for safety basis development

International Nuclear Information System (INIS)

MORENO, M.R.

2003-01-01

DOE-RL has set clear expectations for a cost-effective approach for achieving compliance with the Nuclear Safety Management requirements (10 CFR 830, Nuclear Safety Rule) which will ensure long-term benefit to Hanford. To facilitate implementation of these expectations, tools were developed to streamline and standardize safety analysis and safety document development resulting in a shorter and more predictable DOE approval cycle. A Hanford Safety Analysis and Risk Assessment Handbook (SARAH) was issued to standardized methodologies for development of safety analyses. A Microsoft Excel spreadsheet (RADIDOSE) was issued for the evaluation of radiological consequences for accident scenarios often postulated for Hanford. A standard Site Documented Safety Analysis (DSA) detailing the safety management programs was issued for use as a means of compliance with a majority of 3009 Standard chapters. An in-process review was developed between DOE and the Contractor to facilitate DOE approval and provide early course correction. As a result of setting expectations and providing safety analysis tools, the four Hanford Site waste management nuclear facilities were able to integrate into one Master Waste Management Documented Safety Analysis (WM-DSA)

Developing open source, self-contained disease surveillance software applications for use in resource-limited settings

Directory of Open Access Journals (Sweden)

Campbell Timothy C

2012-09-01

Full Text Available Abstract Background Emerging public health threats often originate in resource-limited countries. In recognition of this fact, the World Health Organization issued revised International Health Regulations in 2005, which call for significantly increased reporting and response capabilities for all signatory nations. Electronic biosurveillance systems can improve the timeliness of public health data collection, aid in the early detection of and response to disease outbreaks, and enhance situational awareness. Methods As components of its Suite for Automated Global bioSurveillance (SAGES program, The Johns Hopkins University Applied Physics Laboratory developed two open-source, electronic biosurveillance systems for use in resource-limited settings. OpenESSENCE provides web-based data entry, analysis, and reporting. ESSENCE Desktop Edition provides similar capabilities for settings without internet access. Both systems may be configured to collect data using locally available cell phone technologies. Results ESSENCE Desktop Edition has been deployed for two years in the Republic of the Philippines. Local health clinics have rapidly adopted the new technology to provide daily reporting, thus eliminating the two-to-three week data lag of the previous paper-based system. Conclusions OpenESSENCE and ESSENCE Desktop Edition are two open-source software products with the capability of significantly improving disease surveillance in a wide range of resource-limited settings. These products, and other emerging surveillance technologies, can assist resource-limited countries compliance with the revised International Health Regulations.

An efficient, scalable, and adaptable framework for solving generic systems of level-set PDEs

Directory of Open Access Journals (Sweden)

Kishore R. Mosaliganti

2013-12-01

Full Text Available In the last decade, level-set methods have been actively developed for applications in image registration, segmentation, tracking, and reconstruction. However, the development of a wide variety of level-set PDEs and their numerical discretization schemes, coupled with hybrid combinations of PDE terms, stopping criteria, and reinitialization strategies, has created a software logistics problem. In the absence of an integrative design, current toolkits support only specific types of level-set implementations which restrict future algorithm development since extensions require significant code duplication and effort. In the new NIH/NLM Insight Toolkit (ITK v4 architecture, we implemented a level-set software design that is flexible to different numerical (continuous, discrete, and sparse and grid representations (point, mesh, and image-based. Given that a generic PDE is a summation of different terms, we used a set of linked containers to which level-set terms can be added or deleted at any point in the evolution process. This container-based approach allows the user to explore and customize terms in the level-set equation at compile-time in a flexible manner. The framework is optimized so that repeated computations of common intensity functions (e.g. gradient and Hessians across multiple terms is eliminated. The framework further enables the evolution of multiple level-sets for multi-object segmentation and processing of large datasets. For doing so, we restrict level-set domains to subsets of the image domain and use multithreading strategies to process groups of subdomains or level-set functions. Users can also select from a variety of reinitialization policies and stopping criteria. Finally, we developed a visualization framework that shows the evolution of a level-set in real-time to help guide algorithm development and parameter optimization. We demonstrate the power of our new framework using confocal microscopy images of cells in a

Vibrational frequency scaling factors for correlation consistent basis sets and the methods CC2 and MP2 and their spin-scaled SCS and SOS variants

Energy Technology Data Exchange (ETDEWEB)

Friese, Daniel H., E-mail: daniel.h.friese@uit.no [Centre for Theoretical and Computational Chemistry CTCC, Department of Chemistry, University of Tromsø, N-9037 Tromsø (Norway); Törk, Lisa; Hättig, Christof, E-mail: christof.haettig@rub.de [Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44801 Bochum (Germany)

2014-11-21

We present scaling factors for vibrational frequencies calculated within the harmonic approximation and the correlated wave-function methods coupled cluster singles and doubles model (CC2) and Møller-Plesset perturbation theory (MP2) with and without a spin-component scaling (SCS or spin-opposite scaling (SOS)). Frequency scaling factors and the remaining deviations from the reference data are evaluated for several non-augmented basis sets of the cc-pVXZ family of generally contracted correlation-consistent basis sets as well as for the segmented contracted TZVPP basis. We find that the SCS and SOS variants of CC2 and MP2 lead to a slightly better accuracy for the scaled vibrational frequencies. The determined frequency scaling factors can also be used for vibrational frequencies calculated for excited states through response theory with CC2 and the algebraic diagrammatic construction through second order and their spin-component scaled variants.

XZP + 1d and XZP + 1d-DKH basis sets for second-row elements: application to CCSD(T) zero-point vibrational energy and atomization energy calculations.

Science.gov (United States)

Campos, Cesar T; Jorge, Francisco E; Alves, Júlia M A

2012-09-01

Recently, segmented all-electron contracted double, triple, quadruple, quintuple, and sextuple zeta valence plus polarization function (XZP, X = D, T, Q, 5, and 6) basis sets for the elements from H to Ar were constructed for use in conjunction with nonrelativistic and Douglas-Kroll-Hess Hamiltonians. In this work, in order to obtain a better description of some molecular properties, the XZP sets for the second-row elements were augmented with high-exponent d "inner polarization functions," which were optimized in the molecular environment at the second-order Møller-Plesset level. At the coupled cluster level of theory, the inclusion of tight d functions for these elements was found to be essential to improve the agreement between theoretical and experimental zero-point vibrational energies (ZPVEs) and atomization energies. For all of the molecules studied, the ZPVE errors were always smaller than 0.5 %. The atomization energies were also improved by applying corrections due to core/valence correlation and atomic spin-orbit effects. This led to estimates for the atomization energies of various compounds in the gaseous phase. The largest error (1.2 kcal mol(-1)) was found for SiH(4).

Relay protection coordination with generator capability curve, excitation system limiters and power system relay protections settings

OpenAIRE

Buha Danilo; Buha Boško; Jačić Dušan; Gligorov Saša; Božilov Marko; Marinković Savo; Milosavljević Srđan

2016-01-01

The relay protection settings performed in the largest thermal powerplant (TE "Nikola Tesla B") are reffered and explained in this paper. The first calculation step is related to the coordination of the maximum stator current limiter settings, the overcurrent protection with inverse characteristics settings and the permitted overload of the generator stator B1. In the second calculation step the settings of impedance generator protection are determined, and the methods and criteria according ...

A parametric level-set approach for topology optimization of flow domains

DEFF Research Database (Denmark)

Pingen, Georg; Waidmann, Matthias; Evgrafov, Anton

2010-01-01

of the design variables in the traditional approaches is seen as a possible cause for the slow convergence. Non-smooth material distributions are suspected to trigger premature onset of instationary flows which cannot be treated by steady-state flow models. In the present work, we study whether the convergence...... and the versatility of topology optimization methods for fluidic systems can be improved by employing a parametric level-set description. In general, level-set methods allow controlling the smoothness of boundaries, yield a non-local influence of design variables, and decouple the material description from the flow...... field discretization. The parametric level-set method used in this study utilizes a material distribution approach to represent flow boundaries, resulting in a non-trivial mapping between design variables and local material properties. Using a hydrodynamic lattice Boltzmann method, we study...

Discussion on the methods for calculation release limits for low-level radioactive waste

International Nuclear Information System (INIS)

Cao Fengbo; Liu Xiaochao

2012-01-01

The release request for low-level radioactive waste are briefly described in this paper. Associating with the conditions of low-level radioactive waste of some radioactive waste processing station, the methods and gist for calculating release limits for low-level radioactive waste with national release limits and annual effective dose limit for the public or the occupation are discussed. Then release limits for the low-level radioactive waste are also proposed. (authors)

Transmission Level High Temperature Superconducting Fault Current Limiter

Energy Technology Data Exchange (ETDEWEB)

Stewart, Gary [SuperPower, Inc., Schenectady, NY (United States)

2016-10-05

The primary objective of this project was to demonstrate the feasibility and reliability of utilizing high-temperature superconducting (HTS) materials in a Transmission Level Superconducting Fault Current Limiter (SFCL) application. During the project, the type of high-temperature superconducting material used evolved from 1^st generation (1G) BSCCO-2212 melt cast bulk high-temperature superconductors to 2^nd generation (2G) YBCO-based high-temperature superconducting tape. The SFCL employed SuperPower's “Matrix” technology, that offers modular features to enable scale up to transmission voltage levels. The SFCL consists of individual modules that contain elements and parallel inductors that assist in carrying the current during the fault. A number of these modules are arranged in an m x n array to form the current-limiting matrix.

Sleep Disordered Breathing in Four Resource-Limited Settings in Peru: Prevalence, Risk Factors, and Association with Chronic Diseases.

Science.gov (United States)

Schwartz, Noah G; Rattner, Adi; Schwartz, Alan R; Mokhlesi, Babak; Gilman, Robert H; Bernabe-Ortiz, Antonio; Miranda, J Jaime; Checkley, William

2015-09-01

Sleep disordered breathing (SDB) is a highly prevalent condition in high-income countries, with major consequences for cardiopulmonary health, public safety, healthcare utilization, and mortality. However, its prevalence and effect in low- and middle-income countries are less well known. We sought to determine the prevalence, risk factors, and comorbidities of SDB symptoms in four resource-limited settings. Cross-sectional analysis of the CRONICAS Cohort, a population-based age- and sex-stratified sample. Four resource-limited settings in Peru varying in altitude, urbanization, and air pollution. There were 2,682 adults aged 35 to 92 y. Self-reported SDB symptoms (habitual snoring, observed apneas, Epworth Sleepiness Scale), sociodemographics, medical history, anthropometrics, spirometry, blood biomarkers were reported. We found a high prevalence of habitual snoring (30.2%, 95% confidence interval [CI] 28.5-32.0%), observed apneas (20.9%, 95% CI 19.4-22.5%) and excessive daytime sleepiness (18.6%, 95% CI 17.1-20.1%). SDB symptoms varied across sites; prevalence and adjusted odds for habitual snoring were greatest at sea level, whereas those for observed apneas were greatest at high altitude. In multivariable analysis, habitual snoring was associated with older age, male sex, body mass index (BMI), and higher socioeconomic status; observed apneas were associated with BMI; and excessive daytime sleepiness was associated with older age, female sex, and medium socioeconomic status. Adjusted odds of cardiovascular disease, depression, and hypertension and total chronic disease burden increased progressively with the number of SDB symptoms. A threefold increase in the odds of having an additional chronic comorbid disease (adjusted odds ratio 3.57, 95% CI 2.18-5.84) was observed in those with all three versus no SDB symptoms. Sleep disordered breathing symptoms were highly prevalent, varied widely across four resource-limited settings in Peru, and exhibited strong

12 CFR 714.9 - Are indirect leasing arrangements subject to the purchase of eligible obligation limit set forth...

Science.gov (United States)

2010-01-01

... the purchase of eligible obligation limit set forth in § 701.23 of this chapter? 714.9 Section 714.9....9 Are indirect leasing arrangements subject to the purchase of eligible obligation limit set forth... underwriting decision and that the lease contract is assigned to you very soon after it is signed by the member...

Multi person detection and tracking based on hierarchical level-set method

Science.gov (United States)

Khraief, Chadia; Benzarti, Faouzi; Amiri, Hamid

2018-04-01

In this paper, we propose an efficient unsupervised method for mutli-person tracking based on hierarchical level-set approach. The proposed method uses both edge and region information in order to effectively detect objects. The persons are tracked on each frame of the sequence by minimizing an energy functional that combines color, texture and shape information. These features are enrolled in covariance matrix as region descriptor. The present method is fully automated without the need to manually specify the initial contour of Level-set. It is based on combined person detection and background subtraction methods. The edge-based is employed to maintain a stable evolution, guide the segmentation towards apparent boundaries and inhibit regions fusion. The computational cost of level-set is reduced by using narrow band technique. Many experimental results are performed on challenging video sequences and show the effectiveness of the proposed method.

Plastic Limit Loads for Slanted Circumferential Through-Wall Cracked Pipes Using 3D Finite-Element Limit Analyses

International Nuclear Information System (INIS)

Jang, Hyun Min; Cho, Doo Ho; Kim, Young Jin; Huh, Nam Su; Shim, Do Jun; Choi, Young Hwan; Park, Jung Soon

2011-01-01

On the basis of detailed 3D finite-element (FE) limit analyses, the plastic limit load solutions for pipes with slanted circumferential through-wall cracks (TWCs) subjected to axial tension, global bending, and internal pressure are reported. The FE model and analysis procedure employed in the present numerical study were validated by comparing the present FE results with existing solutions for plastic limit loads of pipes with idealized TWCs. For the quantification of the effect of slanted crack on plastic limit load, slant correction factors for calculating the plastic limit loads of pipes with slanted TWCs from pipes with idealized TWCs are newly proposed from extensive 3D FE calculations. These slant-correction factors are presented in tabulated form for practical ranges of geometry and for each set of loading conditions

Bush animal attacks: management of complex injuries in a resource-limited setting

Directory of Open Access Journals (Sweden)

Mitchell Katrina B

2011-12-01

Full Text Available Abstract Introduction Though animal-related injuries and fatalities have been documented throughout the world, the variety of attacks by wild animals native to rural East Africa are less commonly described. Given the proximity of our northwestern Tanzania hospital to Lake Victoria, Lake Tanganyika, and the Serengeti National Park, and presentation of several patients attacked by bush animals and suffering a variety of complex injuries, we sought to report the pattern of attacks and surgical management in a resource-limited setting. Materials and methods Four patients who were admitted to the northwestern Tanzania tertiary referral hospital, Bugando Medical Centre (BMC, in 2010-2011 suffered attacks by different bush animals: hyena, elephant, crocodile, and vervet monkey. These patients were triaged as trauma patients in the Casualty Ward, then admitted for inpatient monitoring and treatment. Their outcomes were followed to discharge. Results The age and gender of the patients attacked was variable, though all but the pediatric patient were participating in food gathering or guarding activities in rural locations at the time of the attacks. All patients required surgical management of their injuries, which included debridement and closure of wounds, chest tube insertion, amputation, and external fixation of an extremity fracture. All patients survived and were discharged home. Discussion Though human injuries secondary to encounters with undomesticated animals such as cows, moose, and camel are reported, they often are indirect traumas resulting from road traffic collisions. Snake attacks are well documented and common. However, this series of unique bush animal attacks describes the initial and surgical management of human injuries in the resource-limited setting of the developing world. Conclusion Animal attacks are common throughout the world, but their pattern may vary in Africa throughout jungle and bush environmental settings. It is

Level set methods for detonation shock dynamics using high-order finite elements

Energy Technology Data Exchange (ETDEWEB)

Dobrev, V. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Grogan, F. C. [Univ. of California, San Diego, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kolev, T. V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rieben, R [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tomov, V. Z. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-05-26

Level set methods are a popular approach to modeling evolving interfaces. We present a level set ad- vection solver in two and three dimensions using the discontinuous Galerkin method with high-order nite elements. During evolution, the level set function is reinitialized to a signed distance function to maintain ac- curacy. Our approach leads to stable front propagation and convergence on high-order, curved, unstructured meshes. The ability of the solver to implicitly track moving fronts lends itself to a number of applications; in particular, we highlight applications to high-explosive (HE) burn and detonation shock dynamics (DSD). We provide results for two- and three-dimensional benchmark problems as well as applications to DSD.

An investigation of children's levels of inquiry in an informal science setting

Science.gov (United States)

Clark-Thomas, Beth Anne

Elementary school students' understanding of both science content and processes are enhanced by the higher level thinking associated with inquiry-based science investigations. Informal science setting personnel, elementary school teachers, and curriculum specialists charged with designing inquiry-based investigations would be well served by an understanding of the varying influence of certain present factors upon the students' willingness and ability to delve into such higher level inquiries. This study examined young children's use of inquiry-based materials and factors which may influence the level of inquiry they engaged in during informal science activities. An informal science setting was selected as the context for the examination of student inquiry behaviors because of the rich inquiry-based environment present at the site and the benefits previously noted in the research regarding the impact of informal science settings upon the construction of knowledge in science. The study revealed several patterns of behavior among children when they are engaged in inquiry-based activities at informal science exhibits. These repeated behaviors varied in the children's apparent purposeful use of the materials at the exhibits. These levels of inquiry behavior were taxonomically defined as high/medium/low within this study utilizing a researcher-developed tool. Furthermore, in this study adult interventions, questions, or prompting were found to impact the level of inquiry engaged in by the children. This study revealed that higher levels of inquiry were preceded by task directed and physical feature prompts. Moreover, the levels of inquiry behaviors were haltered, even lowered, when preceded by a prompt that focused on a science content or concept question. Results of this study have implications for the enhancement of inquiry-based science activities in elementary schools as well as in informal science settings. These findings have significance for all science educators

The metabolic response of P. putida KT2442 producing high levels of polyhydroxyalkanoate under single- and multiple-nutrient-limited growth: Highlights from a multi-level omics approach

Directory of Open Access Journals (Sweden)

Poblete-Castro Ignacio

2012-03-01

Full Text Available Abstract Background Pseudomonas putida KT2442 is a natural producer of polyhydroxyalkanoates (PHAs, which can substitute petroleum-based non-renewable plastics and form the basis for the production of tailor-made biopolymers. However, despite the substantial body of work on PHA production by P. putida strains, it is not yet clear how the bacterium re-arranges its whole metabolism when it senses the limitation of nitrogen and the excess of fatty acids as carbon source, to result in a large accumulation of PHAs within the cell. In the present study we investigated the metabolic response of KT2442 using a systems biology approach to highlight the differences between single- and multiple-nutrient-limited growth in chemostat cultures. Results We found that 26, 62, and 81% of the cell dry weight consist of PHA under conditions of carbon, dual, and nitrogen limitation, respectively. Under nitrogen limitation a specific PHA production rate of 0.43 (g·(g·h-1 was obtained. The residual biomass was not constant for dual- and strict nitrogen-limiting growth, showing a different feature in comparison to other P. putida strains. Dual limitation resulted in patterns of gene expression, protein level, and metabolite concentrations that substantially differ from those observed under exclusive carbon or nitrogen limitation. The most pronounced differences were found in the energy metabolism, fatty acid metabolism, as well as stress proteins and enzymes belonging to the transport system. Conclusion This is the first study where the interrelationship between nutrient limitations and PHA synthesis has been investigated under well-controlled conditions using a system level approach. The knowledge generated will be of great assistance for the development of bioprocesses and further metabolic engineering work in this versatile organism to both enhance and diversify the industrial production of PHAs.

A projection-free method for representing plane-wave DFT results in an atom-centered basis

International Nuclear Information System (INIS)

Dunnington, Benjamin D.; Schmidt, J. R.

2015-01-01

Plane wave density functional theory (DFT) is a powerful tool for gaining accurate, atomic level insight into bulk and surface structures. Yet, the delocalized nature of the plane wave basis set hinders the application of many powerful post-computation analysis approaches, many of which rely on localized atom-centered basis sets. Traditionally, this gap has been bridged via projection-based techniques from a plane wave to atom-centered basis. We instead propose an alternative projection-free approach utilizing direct calculation of matrix elements of the converged plane wave DFT Hamiltonian in an atom-centered basis. This projection-free approach yields a number of compelling advantages, including strict orthonormality of the resulting bands without artificial band mixing and access to the Hamiltonian matrix elements, while faithfully preserving the underlying DFT band structure. The resulting atomic orbital representation of the Kohn-Sham wavefunction and Hamiltonian provides a gateway to a wide variety of analysis approaches. We demonstrate the utility of the approach for a diverse set of chemical systems and example analysis approaches

Variational Level Set Method for Two-Stage Image Segmentation Based on Morphological Gradients

Directory of Open Access Journals (Sweden)

Zemin Ren

2014-01-01

Full Text Available We use variational level set method and transition region extraction techniques to achieve image segmentation task. The proposed scheme is done by two steps. We first develop a novel algorithm to extract transition region based on the morphological gradient. After this, we integrate the transition region into a variational level set framework and develop a novel geometric active contour model, which include an external energy based on transition region and fractional order edge indicator function. The external energy is used to drive the zero level set toward the desired image features, such as object boundaries. Due to this external energy, the proposed model allows for more flexible initialization. The fractional order edge indicator function is incorporated into the length regularization term to diminish the influence of noise. Moreover, internal energy is added into the proposed model to penalize the deviation of the level set function from a signed distance function. The results evolution of the level set function is the gradient flow that minimizes the overall energy functional. The proposed model has been applied to both synthetic and real images with promising results.

Aerostructural Level Set Topology Optimization for a Common Research Model Wing

Science.gov (United States)

Dunning, Peter D.; Stanford, Bret K.; Kim, H. Alicia

2014-01-01

The purpose of this work is to use level set topology optimization to improve the design of a representative wing box structure for the NASA common research model. The objective is to minimize the total compliance of the structure under aerodynamic and body force loading, where the aerodynamic loading is coupled to the structural deformation. A taxi bump case was also considered, where only body force loads were applied. The trim condition that aerodynamic lift must balance the total weight of the aircraft is enforced by allowing the root angle of attack to change. The level set optimization method is implemented on an unstructured three-dimensional grid, so that the method can optimize a wing box with arbitrary geometry. Fast matching and upwind schemes are developed for an unstructured grid, which make the level set method robust and efficient. The adjoint method is used to obtain the coupled shape sensitivities required to perform aerostructural optimization of the wing box structure.

A Variational Level Set Model Combined with FCMS for Image Clustering Segmentation

Directory of Open Access Journals (Sweden)

Liming Tang

2014-01-01

Full Text Available The fuzzy C means clustering algorithm with spatial constraint (FCMS is effective for image segmentation. However, it lacks essential smoothing constraints to the cluster boundaries and enough robustness to the noise. Samson et al. proposed a variational level set model for image clustering segmentation, which can get the smooth cluster boundaries and closed cluster regions due to the use of level set scheme. However it is very sensitive to the noise since it is actually a hard C means clustering model. In this paper, based on Samson’s work, we propose a new variational level set model combined with FCMS for image clustering segmentation. Compared with FCMS clustering, the proposed model can get smooth cluster boundaries and closed cluster regions due to the use of level set scheme. In addition, a block-based energy is incorporated into the energy functional, which enables the proposed model to be more robust to the noise than FCMS clustering and Samson’s model. Some experiments on the synthetic and real images are performed to assess the performance of the proposed model. Compared with some classical image segmentation models, the proposed model has a better performance for the images contaminated by different noise levels.

Will the changes proposed to the conceptual framework’s definitions and recognition criteria provide a better basis for the IASB standard setting?

NARCIS (Netherlands)

Brouwer, A.; Hoogendoorn, M.; Naarding, E.

2015-01-01

In this paper we evaluate the International Accounting Standards Board’s (IASB) efforts, in a discussion paper (DP) of 2013, to develop a new conceptual framework (CF) in the light of its stated ambition to establish a robust and consistent basis for future standard setting, thereby guiding standard

Investigation of confined hydrogen atom in spherical cavity, using B-splines basis set

Directory of Open Access Journals (Sweden)

M Barezi

2011-03-01

Full Text Available Studying confined quantum systems (CQS is very important in nano technology. One of the basic CQS is a hydrogen atom confined in spherical cavity. In this article, eigenenergies and eigenfunctions of hydrogen atom in spherical cavity are calculated, using linear variational method. B-splines are used as basis functions, which can easily construct the trial wave functions with appropriate boundary conditions. The main characteristics of B-spline are its high localization and its flexibility. Besides, these functions have numerical stability and are able to spend high volume of calculation with good accuracy. The energy levels as function of cavity radius are analyzed. To check the validity and efficiency of the proposed method, extensive convergence test of eigenenergies in different cavity sizes has been carried out.

Addressing the immediate need for emergency providers in resource-limited settings: the model of a six-month emergency medicine curriculum in Haiti.

Science.gov (United States)

Rouhani, Shada A; Israel, Kerling; Leandre, Fernet; Pierre, Sosthène; Bollman, Brennan; Marsh, Regan H

2018-04-06

In many resource-limited settings, emergency medicine (EM) is underdeveloped and formal EM training limited. Residencies and fellowships are an ideal long-term solution but cannot meet immediate needs for emergency providers, while short-term programs are often too limited in content. We describe a third method successfully implemented in Haiti: a medium-duration certificate program to meet the immediate need for emergency specialists. In conjunction with the Haitian Ministry of Health and National Medical School, we developed and implemented a novel, 6-month EM certificate program to build human resources for health and emergency care capacity. The program consisted of didactic and supervised clinical components, covering core content in EM. Didactics included lectures, simulations, hands-on skill-sessions, and journal clubs. Supervised clinical time reinforced concepts and taught an EM approach to patient care. Fourteen physicians from around Haiti successfully completed the program; all improved from their pre-test to post-test. At the end of the program and 9-month post-program evaluations, participants rated the program highly, and most felt they used their new knowledge daily. Participants found clinical supervision and simulation particularly useful. Key components to our program's success included collaboration with the Ministry of Health and National Medical School, supervised clinical time, and the continual presence of a course director. The program could be improved by a more flexible curriculum and by grouping participants by baseline knowledge levels. Medium-duration certificate programs offer a viable option for addressing immediate human resource gaps in emergency care, and our program offers a model for implementation in resource-limited settings. Similar options should be considered for other emerging specialties in resource-limited settings.

Surface-to-surface registration using level sets

DEFF Research Database (Denmark)

Hansen, Mads Fogtmann; Erbou, Søren G.; Vester-Christensen, Martin

2007-01-01

This paper presents a general approach for surface-to-surface registration (S2SR) with the Euclidean metric using signed distance maps. In addition, the method is symmetric such that the registration of a shape A to a shape B is identical to the registration of the shape B to the shape A. The S2SR...... problem can be approximated by the image registration (IR) problem of the signed distance maps (SDMs) of the surfaces confined to some narrow band. By shrinking the narrow bands around the zero level sets the solution to the IR problem converges towards the S2SR problem. It is our hypothesis...... that this approach is more robust and less prone to fall into local minima than ordinary surface-to-surface registration. The IR problem is solved using the inverse compositional algorithm. In this paper, a set of 40 pelvic bones of Duroc pigs are registered to each other w.r.t. the Euclidean transformation...

System requirements and design description for the document basis database interface (DocBasis)

International Nuclear Information System (INIS)

Lehman, W.J.

1997-01-01

This document describes system requirements and the design description for the Document Basis Database Interface (DocBasis). The DocBasis application is used to manage procedures used within the tank farms. The application maintains information in a small database to track the document basis for a procedure, as well as the current version/modification level and the basis for the procedure. The basis for each procedure is substantiated by Administrative, Technical, Procedural, and Regulatory requirements. The DocBasis user interface was developed by Science Applications International Corporation (SAIC)

Potential low-level waste disposal limits for activation products from fusion

International Nuclear Information System (INIS)

Kennedy, W.E. Jr.; Peloquin, R.A.

1983-09-01

Hanford Engineering Development Laboratory (HEDL) scientists are involved in studies considering alternative construction materials for the first wall of commercial fusion reactors. To permit a comparison of radioactivity levels, both the level of activation and an acceptable limit for the radionuclides present must be known. Generic material composition guidelines can be developed using the US Nuclear Regulatory Commission (NRC) regulations governing the near-surface disposal of low-level radioactive wastes. These regulations consider wastes defined as containing source, special nuclear, or by-product materials arising from research, industrial, medical, and nuclear fuel-cycle activities. However, not all of the activation products produced in low-level wastes from fusion reactors are considered by the NRC in their regulations. The purpose of this report is to present potential low-level waste-disposal limits for ten radionuclides resulting from fusion reactor operations that are not considered in the NRC low-level waste regulations. These potential limits will be used by HEDL scientists to complete their generic material composition guidelines for the first wall of commercial fusion reactors

Microdosimetric basis for exposure limits

International Nuclear Information System (INIS)

Brackenbush, L.W.; Braby, L.A.

1986-10-01

The new organ-weighted effective dose equivalents should provide a much more accurate estimation of the degree of hazard for a worker's exposure to ionizing radiations. The method involves the microdosimetric concept of lineal energy to help establish exposure limits and will provide a unified system applicable to all types of ionizing radiation. Rather than being only calculated values, the effective dose equivalents and quality factors will be experimentally measured using tissue equivalent proportional counters. The measurement may be difficult to perform at various depths in an anthropomorphic phantom. Operational health physicists will be concerned about the lack of survey instruments and personnel dosimeters that measure lineal energy distributions. Their possible objections may be mitigated by the commercial introduction of instruments based upon tissue equivalent proportional counters or related devices containing inexpensive microprocessors. The many potential benefits include providing a uniform method for implementing the proposed increases in quality factors for neutrons and photons, providing a more unified approach for combining external and internal exposures, and potentially resolving questions about dosimeter placement and dose assessment for nonuniform exposures to mixed radiations. 16 refs., 3 figs

Predicting soil formation on the basis of transport-limited chemical weathering

Science.gov (United States)

Yu, Fang; Hunt, Allen Gerhard

2018-01-01

Soil production is closely related to chemical weathering. It has been shown that, under the assumption that chemical weathering is limited by solute transport, the process of soil production is predictable. However, solute transport in soil cannot be described by Gaussian transport. In this paper, we propose an approach based on percolation theory describing non-Gaussian transport of solute to predict soil formation (the net production of soil) by considering both soil production from chemical weathering and removal of soil from erosion. Our prediction shows agreement with observed soil depths in the field. Theoretical soil formation rates are also compared with published rates predicted using soil age-profile thickness (SAST) method. Our formulation can be incorporated directly into landscape evolution models on a point-to-point basis as long as such models account for surface water routing associated with overland flow. Further, our treatment can be scaled-up to address complications associated with continental-scale applications, including those from climate change, such as changes in vegetation, or surface flow organization. The ability to predict soil formation rates has implications for understanding Earth's climate system on account of the relationship to chemical weathering of silicate minerals with the associated drawdown of atmospheric carbon, but it is also important in geomorphology for understanding landscape evolution, including for example, the shapes of hillslopes, and the net transport of sediments to sedimentary basins.

78 FR 70414 - Pricing for the 2013 United States Mint Limited Edition Silver Proof SetTM

Science.gov (United States)

2013-11-25

... DEPARTMENT OF THE TREASURY United States Mint Pricing for the 2013 United States Mint Limited Edition Silver Proof Set TM AGENCY: United States Mint, Department of the Treasury. ACTION: Notice. SUMMARY: The United States Mint is announcing a price of $139.95 for the 2013 United States Mint Limited...

Creating Online Training for Procedures in Global Health with PEARLS (Procedural Education for Adaptation to Resource-Limited Settings).

Science.gov (United States)

Bensman, Rachel S; Slusher, Tina M; Butteris, Sabrina M; Pitt, Michael B; On Behalf Of The Sugar Pearls Investigators; Becker, Amanda; Desai, Brinda; George, Alisha; Hagen, Scott; Kiragu, Andrew; Johannsen, Ron; Miller, Kathleen; Rule, Amy; Webber, Sarah

2017-11-01

The authors describe a multiinstitutional collaborative project to address a gap in global health training by creating a free online platform to share a curriculum for performing procedures in resource-limited settings. This curriculum called PEARLS (Procedural Education for Adaptation to Resource-Limited Settings) consists of peer-reviewed instructional and demonstration videos describing modifications for performing common pediatric procedures in resource-limited settings. Adaptations range from the creation of a low-cost spacer for inhaled medications to a suction chamber for continued evacuation of a chest tube. By describing the collaborative process, we provide a model for educators in other fields to collate and disseminate procedural modifications adapted for their own specialty and location, ideally expanding this crowd-sourced curriculum to reach a wide audience of trainees and providers in global health.

Quench limits

International Nuclear Information System (INIS)

Sapinski, M.

2012-01-01

With thirteen beam induced quenches and numerous Machine Development tests, the current knowledge of LHC magnets quench limits still contains a lot of unknowns. Various approaches to determine the quench limits are reviewed and results of the tests are presented. Attempt to reconstruct a coherent picture emerging from these results is taken. The available methods of computation of the quench levels are presented together with dedicated particle shower simulations which are necessary to understand the tests. The future experiments, needed to reach better understanding of quench limits as well as limits for the machine operation are investigated. The possible strategies to set BLM (Beam Loss Monitor) thresholds are discussed. (author)

A Memory and Computation Efficient Sparse Level-Set Method

NARCIS (Netherlands)

Laan, Wladimir J. van der; Jalba, Andrei C.; Roerdink, Jos B.T.M.

Since its introduction, the level set method has become the favorite technique for capturing and tracking moving interfaces, and found applications in a wide variety of scientific fields. In this paper we present efficient data structures and algorithms for tracking dynamic interfaces through the

On what basis are medical cost-effectiveness thresholds set? Clashing opinions and an absence of data: a systematic review.

Science.gov (United States)

Cameron, David; Ubels, Jasper; Norström, Fredrik

2018-01-01

The amount a government should be willing to invest in adopting new medical treatments has long been under debate. With many countries using formal cost-effectiveness (C/E) thresholds when examining potential new treatments and ever-growing medical costs, accurately setting the level of a C/E threshold can be essential for an efficient healthcare system. The aim of this systematic review is to describe the prominent approaches to setting a C/E threshold, compile available national-level C/E threshold data and willingness-to-pay (WTP) data, and to discern whether associations exist between these values, gross domestic product (GDP) and health-adjusted life expectancy (HALE). This review further examines current obstacles faced with the presently available data. A systematic review was performed to collect articles which have studied national C/E thresholds and willingness-to-pay (WTP) per quality-adjusted life year (QALY) in the general population. Associations between GDP, HALE, WTP, and C/E thresholds were analyzed with correlations. Seventeen countries were identified from nine unique sources to have formal C/E thresholds within our inclusion criteria. Thirteen countries from nine sources were identified to have WTP per QALY data within our inclusion criteria. Two possible associations were identified: C/E thresholds with HALE (quadratic correlation of 0.63), and C/E thresholds with GDP per capita (polynomial correlation of 0.84). However, these results are based on few observations and therefore firm conclusions cannot be made. Most national C/E thresholds identified in our review fall within the WHO's recommended range of one-to-three times GDP per capita. However, the quality and quantity of data available regarding national average WTP per QALY, opportunity costs, and C/E thresholds is poor in comparison to the importance of adequate investment in healthcare. There exists an obvious risk that countries might either over- or underinvest in healthcare if they

Contribution of modifiable risk factors for hypertension and type-2 diabetes in Peruvian resource-limited settings.

Science.gov (United States)

Bernabé-Ortiz, Antonio; Carrillo-Larco, Rodrigo M; Gilman, Robert H; Checkley, William; Smeeth, Liam; Miranda, J Jaime

2016-01-01

It is important to understand the local burden of non-communicable diseases including within-country heterogeneity. The aim of this study was to characterise hypertension and type-2 diabetes profiles across different Peruvian geographical settings emphasising the assessment of modifiable risk factors. Analysis of the CRONICAS Cohort Study baseline assessment was conducted. Cardiometabolic outcomes were blood pressure categories (hypertension, prehypertension, normal) and glucose metabolism disorder status (diabetes, prediabetes, normal). Exposures were study setting and six modifiable factors (smoking, alcohol drinking, leisure time and transport-related physical activity levels, TV watching, fruit/vegetables intake and obesity). Poisson regression models were used to report prevalence ratios (PR). Population attributable risks (PAR) were also estimated. Data from 3238 participants, 48.3% male, mean age 45.3 years, were analysed. Age-standardised (WHO population) prevalence of prehypertension and hypertension was 24% and 16%, whereas for prediabetes and type-2 diabetes it was 18% and 6%, respectively. Outcomes varied according to study setting (pdiabetes. PAR showed that obesity was an important determinant for hypertension (15.7%) and type-2 diabetes (23.9%). There is an evident heterogeneity in the prevalence of and risk factors for hypertension and diabetes within Peru. Prehypertension and prediabetes are highly prevalent across settings. Our results emphasise the need of understanding the epidemiology of cardiometabolic conditions to appropriately implement interventions to tackle the burden of non-communicable diseases. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Sea ice in the Baltic Sea - revisiting BASIS ice, a~historical data set covering the period 1960/1961-1978/1979

Science.gov (United States)

Löptien, U.; Dietze, H.

2014-06-01

The Baltic Sea is a seasonally ice-covered, marginal sea, situated in central northern Europe. It is an essential waterway connecting highly industrialised countries. Because ship traffic is intermittently hindered by sea ice, the local weather services have been monitoring sea ice conditions for decades. In the present study we revisit a historical monitoring data set, covering the winters 1960/1961. This data set, dubbed Data Bank for Baltic Sea Ice and Sea Surface Temperatures (BASIS) ice, is based on hand-drawn maps that were collected and then digitised 1981 in a joint project of the Finnish Institute of Marine Research (today Finish Meteorological Institute (FMI)) and the Swedish Meteorological and Hydrological Institute (SMHI). BASIS ice was designed for storage on punch cards and all ice information is encoded by five digits. This makes the data hard to access. Here we present a post-processed product based on the original five-digit code. Specifically, we convert to standard ice quantities (including information on ice types), which we distribute in the current and free Network Common Data Format (NetCDF). Our post-processed data set will help to assess numerical ice models and provide easy-to-access unique historical reference material for sea ice in the Baltic Sea. In addition we provide statistics showcasing the data quality. The website www.baltic-ocean.org hosts the post-prossed data and the conversion code. The data are also archived at the Data Publisher for Earth & Environmental Science PANGEA (doi:10.1594/PANGEA.832353).

Sea ice in the Baltic Sea - revisiting BASIS ice, a historical data set covering the period 1960/1961-1978/1979

Science.gov (United States)

Löptien, U.; Dietze, H.

2014-12-01

The Baltic Sea is a seasonally ice-covered, marginal sea in central northern Europe. It is an essential waterway connecting highly industrialised countries. Because ship traffic is intermittently hindered by sea ice, the local weather services have been monitoring sea ice conditions for decades. In the present study we revisit a historical monitoring data set, covering the winters 1960/1961 to 1978/1979. This data set, dubbed Data Bank for Baltic Sea Ice and Sea Surface Temperatures (BASIS) ice, is based on hand-drawn maps that were collected and then digitised in 1981 in a joint project of the Finnish Institute of Marine Research (today the Finnish Meteorological Institute (FMI)) and the Swedish Meteorological and Hydrological Institute (SMHI). BASIS ice was designed for storage on punch cards and all ice information is encoded by five digits. This makes the data hard to access. Here we present a post-processed product based on the original five-digit code. Specifically, we convert to standard ice quantities (including information on ice types), which we distribute in the current and free Network Common Data Format (NetCDF). Our post-processed data set will help to assess numerical ice models and provide easy-to-access unique historical reference material for sea ice in the Baltic Sea. In addition we provide statistics showcasing the data quality. The website http://www.baltic-ocean.org hosts the post-processed data and the conversion code. The data are also archived at the Data Publisher for Earth & Environmental Science, PANGAEA (doi:10.1594/PANGAEA.832353).

Level sets and extrema of random processes and fields

CERN Document Server

Azais, Jean-Marc

2009-01-01

A timely and comprehensive treatment of random field theory with applications across diverse areas of study Level Sets and Extrema of Random Processes and Fields discusses how to understand the properties of the level sets of paths as well as how to compute the probability distribution of its extremal values, which are two general classes of problems that arise in the study of random processes and fields and in related applications. This book provides a unified and accessible approach to these two topics and their relationship to classical theory and Gaussian processes and fields, and the most modern research findings are also discussed. The authors begin with an introduction to the basic concepts of stochastic processes, including a modern review of Gaussian fields and their classical inequalities. Subsequent chapters are devoted to Rice formulas, regularity properties, and recent results on the tails of the distribution of the maximum. Finally, applications of random fields to various areas of mathematics a...

Skull defect reconstruction based on a new hybrid level set.

Science.gov (United States)

Zhang, Ziqun; Zhang, Ran; Song, Zhijian

2014-01-01

Skull defect reconstruction is an important aspect of surgical repair. Historically, a skull defect prosthesis was created by the mirroring technique, surface fitting, or formed templates. These methods are not based on the anatomy of the individual patient's skull, and therefore, the prosthesis cannot precisely correct the defect. This study presented a new hybrid level set model, taking into account both the global optimization region information and the local accuracy edge information, while avoiding re-initialization during the evolution of the level set function. Based on the new method, a skull defect was reconstructed, and the skull prosthesis was produced by rapid prototyping technology. This resulted in a skull defect prosthesis that well matched the skull defect with excellent individual adaptation.

76 FR 9004 - Public Comment on Setting Achievement Levels in Writing

Science.gov (United States)

2011-02-16

... DEPARTMENT OF EDUCATION Public Comment on Setting Achievement Levels in Writing AGENCY: U.S... Achievement Levels in Writing. SUMMARY: The National Assessment Governing Board (Governing Board) is... for NAEP in writing. This notice provides opportunity for public comment and submitting...

Basis set effects on the energy and hardness profiles of the ...

Indian Academy of Sciences (India)

Unknown

maximum hardness principle (MHP); spurious stationary points; hydrogen fluoride dimer. 1. Introduction ... This error can be solved when accounting for the basis ..... DURSI for financial support through the Distinguished. University Research ...

Global Health: Preparation for Working in Resource-Limited Settings.

Science.gov (United States)

St Clair, Nicole E; Pitt, Michael B; Bakeera-Kitaka, Sabrina; McCall, Natalie; Lukolyo, Heather; Arnold, Linda D; Audcent, Tobey; Batra, Maneesh; Chan, Kevin; Jacquet, Gabrielle A; Schutze, Gordon E; Butteris, Sabrina

2017-11-01

Trainees and clinicians from high-income countries are increasingly engaging in global health (GH) efforts, particularly in resource-limited settings. Concomitantly, there is a growing demand for these individuals to be better prepared for the common challenges and controversies inherent in GH work. This is a state-of-the-art review article in which we outline what is known about the current scope of trainee and clinician involvement in GH experiences, highlight specific considerations and issues pertinent to GH engagement, and summarize preparation recommendations that have emerged from the literature. The article is focused primarily on short-term GH experiences, although much of the content is also pertinent to long-term work. Suggestions are made for the health care community to develop and implement widely endorsed preparation standards for trainees, clinicians, and organizations engaging in GH experiences and partnerships. Copyright © 2017 by the American Academy of Pediatrics.

Demons versus level-set motion registration for coronary 18F-sodium fluoride PET

Science.gov (United States)

Rubeaux, Mathieu; Joshi, Nikhil; Dweck, Marc R.; Fletcher, Alison; Motwani, Manish; Thomson, Louise E.; Germano, Guido; Dey, Damini; Berman, Daniel S.; Newby, David E.; Slomka, Piotr J.

2016-03-01

Ruptured coronary atherosclerotic plaques commonly cause acute myocardial infarction. It has been recently shown that active microcalcification in the coronary arteries, one of the features that characterizes vulnerable plaques at risk of rupture, can be imaged using cardiac gated 18F-sodium fluoride (18F-NaF) PET. We have shown in previous work that a motion correction technique applied to cardiac-gated 18F-NaF PET images can enhance image quality and improve uptake estimates. In this study, we further investigated the applicability of different algorithms for registration of the coronary artery PET images. In particular, we aimed to compare demons vs. level-set nonlinear registration techniques applied for the correction of cardiac motion in coronary 18F-NaF PET. To this end, fifteen patients underwent 18F-NaF PET and prospective coronary CT angiography (CCTA). PET data were reconstructed in 10 ECG gated bins; subsequently these gated bins were registered using demons and level-set methods guided by the extracted coronary arteries from CCTA, to eliminate the effect of cardiac motion on PET images. Noise levels, target-to-background ratios (TBR) and global motion were compared to assess image quality. Compared to the reference standard of using only diastolic PET image (25% of the counts from PET acquisition), cardiac motion registration using either level-set or demons techniques almost halved image noise due to the use of counts from the full PET acquisition and increased TBR difference between 18F-NaF positive and negative lesions. The demons method produces smoother deformation fields, exhibiting no singularities (which reflects how physically plausible the registration deformation is), as compared to the level-set method, which presents between 4 and 8% of singularities, depending on the coronary artery considered. In conclusion, the demons method produces smoother motion fields as compared to the level-set method, with a motion that is physiologically

Development of limiting decay heat values

International Nuclear Information System (INIS)

Khotylev, V.A.; Thompson, J.W.; Gibb, R.A.

1999-01-01

A number of tools are used in the assessment of decay heat during an outage of the CANDU-6. Currently, the technical basis for all of these tools is 'CANDU Channel Decay Power', Reference 1. The methods used in that document were limited to channel decay powers. However, for most outage support analysis, decay heat limits are based on bundle heats. Since the production of that document in 1977, new versions of codes, and updates of general-purpose and CANDU-specific libraries have become available. These tools and libraries have both a more formal technical basis than Reference 1, and also a more formal validation base. Using these tools it is now possible to derive decay heat with more specific input parameters, such as fuel composition, heat per unit of fuel, and irradiation history, and to assign systematically derived uncertainty allowances to such decay heat values. In particular, we sought to examine a broad range of likely bundle histories, and thus establish a set of limiting bundle decay beat values, that could serve as a bounding envelope for use in Nuclear Safety Analysis. (author)

Modernized level limiters for petroleum products during pouring into railway cars

Energy Technology Data Exchange (ETDEWEB)

Batrakov, B.P.; Bakshi, A.S.; Efremov, V.A.

1983-01-01

The drawbacks of the POUN-1 and POUN-2 pouring limiters are examined and a brief description of the POUN-1M level limiter is given. The device is modernized and is designed for operation with pressure differentials up to 5 kilograms per square centimeter is approved for the premium quality level and is series manufactured by the ''Starorusspribor'' factory. It is noted that at the Neftekhimavtomatika Scientific and Industrial Association factory is planning to manufacture the first industrial series of the POUN-2M level limiters which are designed for pressure differentials up to seven kilograms per square centimeter. Unlike the basic design, the POUN-2M device is equipped with a hydraulic shock and a flow generator which controls the fluid flow rate during the time the sealing valve is closed.

Science Curriculum Guide, Level 4.

Science.gov (United States)

Newark School District, DE.

The fourth of four levels in a K-12 science curriculum is outlined. In Level 4 (grades 9-12), science areas include earth science, biology, chemistry, and physics. Six major themes provide the basis for study in all levels (K-12). These are: Change, Continuity, Diversity, Interaction, Limitation, and Organization. In Level 4, all six themes are…

Simulating Metabolite Basis Sets for in vivo MRS Quantification; Incorporating details of the PRESS Pulse Sequence by means of the GAMMA C++ library

NARCIS (Netherlands)

Van der Veen, J.W.; Van Ormondt, D.; De Beer, R.

2012-01-01

In this work we report on generating/using simulated metabolite basis sets for the quantification of in vivo MRS signals, assuming that they have been acquired by using the PRESS pulse sequence. To that end we have employed the classes and functions of the GAMMA C++ library. By using several

Excited state nuclear forces from the Tamm-Dancoff approximation to time-dependent density functional theory within the plane wave basis set framework

Science.gov (United States)

Hutter, Jürg

2003-03-01

An efficient formulation of time-dependent linear response density functional theory for the use within the plane wave basis set framework is presented. The method avoids the transformation of the Kohn-Sham matrix into the canonical basis and references virtual orbitals only through a projection operator. Using a Lagrangian formulation nuclear derivatives of excited state energies within the Tamm-Dancoff approximation are derived. The algorithms were implemented into a pseudo potential/plane wave code and applied to the calculation of adiabatic excitation energies, optimized geometries and vibrational frequencies of three low lying states of formaldehyde. An overall good agreement with other time-dependent density functional calculations, multireference configuration interaction calculations and experimental data was found.

Stabilized Conservative Level Set Method with Adaptive Wavelet-based Mesh Refinement

Science.gov (United States)

Shervani-Tabar, Navid; Vasilyev, Oleg V.

2016-11-01

This paper addresses one of the main challenges of the conservative level set method, namely the ill-conditioned behavior of the normal vector away from the interface. An alternative formulation for reconstruction of the interface is proposed. Unlike the commonly used methods which rely on the unit normal vector, Stabilized Conservative Level Set (SCLS) uses a modified renormalization vector with diminishing magnitude away from the interface. With the new formulation, in the vicinity of the interface the reinitialization procedure utilizes compressive flux and diffusive terms only in the normal direction to the interface, thus, preserving the conservative level set properties, while away from the interfaces the directional diffusion mechanism automatically switches to homogeneous diffusion. The proposed formulation is robust and general. It is especially well suited for use with adaptive mesh refinement (AMR) approaches due to need for a finer resolution in the vicinity of the interface in comparison with the rest of the domain. All of the results were obtained using the Adaptive Wavelet Collocation Method, a general AMR-type method, which utilizes wavelet decomposition to adapt on steep gradients in the solution while retaining a predetermined order of accuracy.

Some numerical studies of interface advection properties of level set ...

Indian Academy of Sciences (India)

explicit computational elements moving through an Eulerian grid. ... location. The interface is implicitly defined (captured) as the location of the discontinuity in the ... This level set function is advected with the background flow field and thus ...

Evaluation of a four-item DSM-5 Limited Prosocial Emotions specifier scale within and across settings with Spanish children.

Science.gov (United States)

Seijas, Raquel; Servera, Mateu; García-Banda, Gloria; Barry, Christopher T; Burns, G Leonard

2018-04-01

The objective was to evaluate a 4-item measure of the DSM-5 Limited Prosocial Emotions (LPE) specifier (a 4-item measure of prosocial emotions). Mothers, fathers, primary teachers, and ancillary teachers completed measures of prosocial emotions (PE), oppositional defiant disorder (ODD), attention-deficit/hyperactivity disorder (ADHD)-inattention (IN), ADHD-hyperactivity/impulsivity (HI), academic and social impairment on 811 Spanish first-grade children (46% girls). Confirmatory factor and structural regression analyses showed PE symptom scores to have (a) good reliability for the 4 sources (80% to 89% true score variance), (b) invariance of like-symptom loadings and intercepts across the 4 sources, (c) strong convergent and discriminant validity within home and school settings, (d) no convergent validity across settings, and (e) associations with academic and social impairment independent of the ODD dimension (the unique effects of PE also remained significant after controlling for ODD, ADHD-IN, and ADHD-HI for mothers and ancillary teachers). A graded response item response theory analysis indicated that PE scores provided an accurate measure of the PE trait across a wide trait range and especially at low PE trait levels (i.e., scores in the clinical range). Findings also supported the DSM-5 diagnostic criteria of 2 or more LPE symptoms in 2 or more settings (e.g., high levels of the LPE trait were associated with the occurrence of 2 or more symptoms with 4% of the sample showing 2 or more symptoms in both settings). Although additional studies are still required, the PE measure appears useful as a brief measure of the LPE specifier. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

A Cartesian Adaptive Level Set Method for Two-Phase Flows

Science.gov (United States)

Ham, F.; Young, Y.-N.

2003-01-01

In the present contribution we develop a level set method based on local anisotropic Cartesian adaptation as described in Ham et al. (2002). Such an approach should allow for the smallest possible Cartesian grid capable of resolving a given flow. The remainder of the paper is organized as follows. In section 2 the level set formulation for free surface calculations is presented and its strengths and weaknesses relative to the other free surface methods reviewed. In section 3 the collocated numerical method is described. In section 4 the method is validated by solving the 2D and 3D drop oscilation problem. In section 5 we present some results from more complex cases including the 3D drop breakup in an impulsively accelerated free stream, and the 3D immiscible Rayleigh-Taylor instability. Conclusions are given in section 6.

Setting Healthcare Priorities at the Macro and Meso Levels: A Framework for Evaluation.

Science.gov (United States)

Barasa, Edwine W; Molyneux, Sassy; English, Mike; Cleary, Susan

2015-09-16

Priority setting in healthcare is a key determinant of health system performance. However, there is no widely accepted priority setting evaluation framework. We reviewed literature with the aim of developing and proposing a framework for the evaluation of macro and meso level healthcare priority setting practices. We systematically searched Econlit, PubMed, CINAHL, and EBSCOhost databases and supplemented this with searches in Google Scholar, relevant websites and reference lists of relevant papers. A total of 31 papers on evaluation of priority setting were identified. These were supplemented by broader theoretical literature related to evaluation of priority setting. A conceptual review of selected papers was undertaken. Based on a synthesis of the selected literature, we propose an evaluative framework that requires that priority setting practices at the macro and meso levels of the health system meet the following conditions: (1) Priority setting decisions should incorporate both efficiency and equity considerations as well as the following outcomes; (a) Stakeholder satisfaction, (b) Stakeholder understanding, (c) Shifted priorities (reallocation of resources), and (d) Implementation of decisions. (2) Priority setting processes should also meet the procedural conditions of (a) Stakeholder engagement, (b) Stakeholder empowerment, (c) Transparency, (d) Use of evidence, (e) Revisions, (f) Enforcement, and (g) Being grounded on community values. Available frameworks for the evaluation of priority setting are mostly grounded on procedural requirements, while few have included outcome requirements. There is, however, increasing recognition of the need to incorporate both consequential and procedural considerations in priority setting practices. In this review, we adapt an integrative approach to develop and propose a framework for the evaluation of priority setting practices at the macro and meso levels that draws from these complementary schools of thought. © 2015

Setting Healthcare Priorities at the Macro and Meso Levels: A Framework for Evaluation

Science.gov (United States)

Barasa, Edwine W.; Molyneux, Sassy; English, Mike; Cleary, Susan

2015-01-01

Background: Priority setting in healthcare is a key determinant of health system performance. However, there is no widely accepted priority setting evaluation framework. We reviewed literature with the aim of developing and proposing a framework for the evaluation of macro and meso level healthcare priority setting practices. Methods: We systematically searched Econlit, PubMed, CINAHL, and EBSCOhost databases and supplemented this with searches in Google Scholar, relevant websites and reference lists of relevant papers. A total of 31 papers on evaluation of priority setting were identified. These were supplemented by broader theoretical literature related to evaluation of priority setting. A conceptual review of selected papers was undertaken. Results: Based on a synthesis of the selected literature, we propose an evaluative framework that requires that priority setting practices at the macro and meso levels of the health system meet the following conditions: (1) Priority setting decisions should incorporate both efficiency and equity considerations as well as the following outcomes; (a) Stakeholder satisfaction, (b) Stakeholder understanding, (c) Shifted priorities (reallocation of resources), and (d) Implementation of decisions. (2) Priority setting processes should also meet the procedural conditions of (a) Stakeholder engagement, (b) Stakeholder empowerment, (c) Transparency, (d) Use of evidence, (e) Revisions, (f) Enforcement, and (g) Being grounded on community values. Conclusion: Available frameworks for the evaluation of priority setting are mostly grounded on procedural requirements, while few have included outcome requirements. There is, however, increasing recognition of the need to incorporate both consequential and procedural considerations in priority setting practices. In this review, we adapt an integrative approach to develop and propose a framework for the evaluation of priority setting practices at the macro and meso levels that draws from these

Setting Healthcare Priorities at the Macro and Meso Levels: A Framework for Evaluation

Directory of Open Access Journals (Sweden)

Edwine W. Barasa

2015-11-01

Full Text Available Background Priority setting in healthcare is a key determinant of health system performance. However, there is no widely accepted priority setting evaluation framework. We reviewed literature with the aim of developing and proposing a framework for the evaluation of macro and meso level healthcare priority setting practices. Methods We systematically searched Econlit, PubMed, CINAHL, and EBSCOhost databases and supplemented this with searches in Google Scholar, relevant websites and reference lists of relevant papers. A total of 31 papers on evaluation of priority setting were identified. These were supplemented by broader theoretical literature related to evaluation of priority setting. A conceptual review of selected papers was undertaken. Results Based on a synthesis of the selected literature, we propose an evaluative framework that requires that priority setting practices at the macro and meso levels of the health system meet the following conditions: (1 Priority setting decisions should incorporate both efficiency and equity considerations as well as the following outcomes; (a Stakeholder satisfaction, (b Stakeholder understanding, (c Shifted priorities (reallocation of resources, and (d Implementation of decisions. (2 Priority setting processes should also meet the procedural conditions of (a Stakeholder engagement, (b Stakeholder empowerment, (c Transparency, (d Use of evidence, (e Revisions, (f Enforcement, and (g Being grounded on community values. Conclusion Available frameworks for the evaluation of priority setting are mostly grounded on procedural requirements, while few have included outcome requirements. There is, however, increasing recognition of the need to incorporate both consequential and procedural considerations in priority setting practices. In this review, we adapt an integrative approach to develop and propose a framework for the evaluation of priority setting practices at the macro and meso levels that draws from

Heritability and genetic basis of protein level variation in an outbred population.

Science.gov (United States)

Parts, Leopold; Liu, Yi-Chun; Tekkedil, Manu M; Steinmetz, Lars M; Caudy, Amy A; Fraser, Andrew G; Boone, Charles; Andrews, Brenda J; Rosebrock, Adam P

2014-08-01

The genetic basis of heritable traits has been studied for decades. Although recent mapping efforts have elucidated genetic determinants of transcript levels, mapping of protein abundance has lagged. Here, we analyze levels of 4084 GFP-tagged yeast proteins in the progeny of a cross between a laboratory and a wild strain using flow cytometry and high-content microscopy. The genotype of trans variants contributed little to protein level variation between individual cells but explained >50% of the variance in the population's average protein abundance for half of the GFP fusions tested. To map trans-acting factors responsible, we performed flow sorting and bulk segregant analysis of 25 proteins, finding a median of five protein quantitative trait loci (pQTLs) per GFP fusion. Further, we find that cis-acting variants predominate; the genotype of a gene and its surrounding region had a large effect on protein level six times more frequently than the rest of the genome combined. We present evidence for both shared and independent genetic control of transcript and protein abundance: More than half of the expression QTLs (eQTLs) contribute to changes in protein levels of regulated genes, but several pQTLs do not affect their cognate transcript levels. Allele replacements of genes known to underlie trans eQTL hotspots confirmed the correlation of effects on mRNA and protein levels. This study represents the first genome-scale measurement of genetic contribution to protein levels in single cells and populations, identifies more than a hundred trans pQTLs, and validates the propagation of effects associated with transcript variation to protein abundance. © 2014 Parts et al.; Published by Cold Spring Harbor Laboratory Press.

Risk based limits for Operational Safety Requirements

International Nuclear Information System (INIS)

Cappucci, A.J. Jr.

1993-01-01

OSR limits are designed to protect the assumptions made in the facility safety analysis in order to preserve the safety envelope during facility operation. Normally, limits are set based on ''worst case conditions'' without regard to the likelihood (frequency) of a credible event occurring. In special cases where the accident analyses are based on ''time at risk'' arguments, it may be desirable to control the time at which the facility is at risk. A methodology has been developed to use OSR limits to control the source terms and the times these source terms would be available, thus controlling the acceptable risk to a nuclear process facility. The methodology defines a new term ''gram-days''. This term represents the area under a source term (inventory) vs time curve which represents the risk to the facility. Using the concept of gram-days (normalized to one year) allows the use of an accounting scheme to control the risk under the inventory vs time curve. The methodology results in at least three OSR limits: (1) control of the maximum inventory or source term, (2) control of the maximum gram-days for the period based on a source term weighted average, and (3) control of the maximum gram-days at the individual source term levels. Basing OSR limits on risk based safety analysis is feasible, and a basis for development of risk based limits is defensible. However, monitoring inventories and the frequencies required to maintain facility operation within the safety envelope may be complex and time consuming

Advanced Fuel Cycle Cost Basis

Energy Technology Data Exchange (ETDEWEB)

D. E. Shropshire; K. A. Williams; W. B. Boore; J. D. Smith; B. W. Dixon; M. Dunzik-Gougar; R. D. Adams; D. Gombert; E. Schneider

2009-12-01

This report, commissioned by the U.S. Department of Energy (DOE), provides a comprehensive set of cost data supporting a cost analysis for the relative economic comparison of options for use in the Advanced Fuel Cycle Initiative (AFCI) Program. The report describes the AFCI cost basis development process, reference information on AFCI cost modules, a procedure for estimating fuel cycle costs, economic evaluation guidelines, and a discussion on the integration of cost data into economic computer models. This report contains reference cost data for 25 cost modules—23 fuel cycle cost modules and 2 reactor modules. The cost modules were developed in the areas of natural uranium mining and milling, conversion, enrichment, depleted uranium disposition, fuel fabrication, interim spent fuel storage, reprocessing, waste conditioning, spent nuclear fuel (SNF) packaging, long-term monitored retrievable storage, near surface disposal of low-level waste (LLW), geologic repository and other disposal concepts, and transportation processes for nuclear fuel, LLW, SNF, transuranic, and high-level waste.

Advanced Fuel Cycle Cost Basis

Energy Technology Data Exchange (ETDEWEB)

D. E. Shropshire; K. A. Williams; W. B. Boore; J. D. Smith; B. W. Dixon; M. Dunzik-Gougar; R. D. Adams; D. Gombert

2007-04-01

This report, commissioned by the U.S. Department of Energy (DOE), provides a comprehensive set of cost data supporting a cost analysis for the relative economic comparison of options for use in the Advanced Fuel Cycle Initiative (AFCI) Program. The report describes the AFCI cost basis development process, reference information on AFCI cost modules, a procedure for estimating fuel cycle costs, economic evaluation guidelines, and a discussion on the integration of cost data into economic computer models. This report contains reference cost data for 26 cost modules—24 fuel cycle cost modules and 2 reactor modules. The cost modules were developed in the areas of natural uranium mining and milling, conversion, enrichment, depleted uranium disposition, fuel fabrication, interim spent fuel storage, reprocessing, waste conditioning, spent nuclear fuel (SNF) packaging, long-term monitored retrievable storage, near surface disposal of low-level waste (LLW), geologic repository and other disposal concepts, and transportation processes for nuclear fuel, LLW, SNF, and high-level waste.

Advanced Fuel Cycle Cost Basis

Energy Technology Data Exchange (ETDEWEB)

D. E. Shropshire; K. A. Williams; W. B. Boore; J. D. Smith; B. W. Dixon; M. Dunzik-Gougar; R. D. Adams; D. Gombert; E. Schneider

2008-03-01

This report, commissioned by the U.S. Department of Energy (DOE), provides a comprehensive set of cost data supporting a cost analysis for the relative economic comparison of options for use in the Advanced Fuel Cycle Initiative (AFCI) Program. The report describes the AFCI cost basis development process, reference information on AFCI cost modules, a procedure for estimating fuel cycle costs, economic evaluation guidelines, and a discussion on the integration of cost data into economic computer models. This report contains reference cost data for 25 cost modules—23 fuel cycle cost modules and 2 reactor modules. The cost modules were developed in the areas of natural uranium mining and milling, conversion, enrichment, depleted uranium disposition, fuel fabrication, interim spent fuel storage, reprocessing, waste conditioning, spent nuclear fuel (SNF) packaging, long-term monitored retrievable storage, near surface disposal of low-level waste (LLW), geologic repository and other disposal concepts, and transportation processes for nuclear fuel, LLW, SNF, transuranic, and high-level waste.

Level Sets and Voronoi based Feature Extraction from any Imagery

DEFF Research Database (Denmark)

Sharma, O.; Anton, François; Mioc, Darka

2012-01-01

Polygon features are of interest in many GEOProcessing applications like shoreline mapping, boundary delineation, change detection, etc. This paper presents a unique new GPU-based methodology to automate feature extraction combining level sets, or mean shift based segmentation together with Voron...

Online monitoring of oil film using electrical capacitance tomography and level set method

International Nuclear Information System (INIS)

Xue, Q.; Ma, M.; Sun, B. Y.; Cui, Z. Q.; Wang, H. X.

2015-01-01

In the application of oil-air lubrication system, electrical capacitance tomography (ECT) provides a promising way for monitoring oil film in the pipelines by reconstructing cross sectional oil distributions in real time. While in the case of small diameter pipe and thin oil film, the thickness of the oil film is hard to be observed visually since the interface of oil and air is not obvious in the reconstructed images. And the existence of artifacts in the reconstructions has seriously influenced the effectiveness of image segmentation techniques such as level set method. Besides, level set method is also unavailable for online monitoring due to its low computation speed. To address these problems, a modified level set method is developed: a distance regularized level set evolution formulation is extended to image two-phase flow online using an ECT system, a narrowband image filter is defined to eliminate the influence of artifacts, and considering the continuity of the oil distribution variation, the detected oil-air interface of a former image can be used as the initial contour for the detection of the subsequent frame; thus, the propagation from the initial contour to the boundary can be greatly accelerated, making it possible for real time tracking. To testify the feasibility of the proposed method, an oil-air lubrication facility with 4 mm inner diameter pipe is measured in normal operation using an 8-electrode ECT system. Both simulation and experiment results indicate that the modified level set method is capable of visualizing the oil-air interface accurately online

Methodology for setting the reference levels in the measurements of the dose rate absorbed in air due to the environmental gamma radiation

International Nuclear Information System (INIS)

Dominguez Ley, Orlando; Capote Ferrera, Eduardo; Caveda Ramos, Celia; Alonso Abad, Dolores

2008-01-01

Full text: The methodology for setting the reference levels of the measurements of the gamma dose rate absorbed in the air is described. The registration level was obtained using statistical methods. To set the alarm levels, it was necessary to begin with certain affectation level, which activates the investigation operation mode when being reached. It is was necessary to transform this affectation level into values of the indicators selected to set the appearance of an alarm in the network, allowing its direct comparison and at the same time a bigger operability of this one. The affectation level was assumed as an effective dose of 1 mSv/y, which is the international dose limit for public. The conversion factor obtained in a practical way as a consequence of the Chernobyl accident was assumed, converting the value of annual effective dose into values of effective dose rate in air. These factors are the most important in our work, since the main task of the National Network of Environmental Radiological Surveillance of the Republic of Cuba is detecting accidents with a situations regional affectation, and this accident is precisely an example of pollution at this scale. The alarm level setting was based on the results obtained in the first year of the Chernobyl accident. For this purpose, some transformations were achieved. In the final results, a correction factor was introduced depending on the year season the measurement was made. It was taken into account the influence of different meteorological events on the measurement of this indicator. (author)

A level-set method for two-phase flows with soluble surfactant

Science.gov (United States)

Xu, Jian-Jun; Shi, Weidong; Lai, Ming-Chih

2018-01-01

A level-set method is presented for solving two-phase flows with soluble surfactant. The Navier-Stokes equations are solved along with the bulk surfactant and the interfacial surfactant equations. In particular, the convection-diffusion equation for the bulk surfactant on the irregular moving domain is solved by using a level-set based diffusive-domain method. A conservation law for the total surfactant mass is derived, and a re-scaling procedure for the surfactant concentrations is proposed to compensate for the surfactant mass loss due to numerical diffusion. The whole numerical algorithm is easy for implementation. Several numerical simulations in 2D and 3D show the effects of surfactant solubility on drop dynamics under shear flow.

Evaluation of a Low-Cost Bubble CPAP System Designed for Resource-Limited Settings.

Science.gov (United States)

Bennett, Desmond J; Carroll, Ryan W; Kacmarek, Robert M

2018-04-01

Respiratory compromise is a leading contributor to global neonatal death. CPAP is a method of treatment that helps maintain lung volume during expiration, promotes comfortable breathing, and improves oxygenation. Bubble CPAP is an effective alternative to standard CPAP. We sought to determine the reliability and functionality of a low-cost bubble CPAP device designed for low-resource settings. The low-cost bubble CPAP device was compared to a commercially available bubble CPAP system. The devices were connected to a lung simulator that simulated neonates of 4 different weights with compromised respiratory mechanics (∼1, ∼3, ∼5, and ∼10 kg). The devices' abilities to establish and maintain pressure and flow under normal conditions as well as under conditions of leak were compared. Multiple combinations of pressure levels (5, 8, and 10 cm H 2 O) and flow levels (3, 6, and 10 L/min) were tested. The endurance of both devices was also tested by running the systems continuously for 8 h and measuring the changes in pressure and flow. Both devices performed equivalently during the no-leak and leak trials. While our testing revealed individual differences that were statistically significant and clinically important (>10% difference) within specific CPAP and flow-level settings, no overall comparisons of CPAP or flow were both statistically significant and clinically important. Each device delivered pressures similar to the desired pressures, although the flows delivered by both machines were lower than the set flows in most trials. During the endurance trials, the low-cost device was marginally better at maintaining pressure, while the commercially available device was better at maintaining flow. The low-cost bubble CPAP device evaluated in this study is comparable to a bubble CPAP system used in developed settings. Extensive clinical trials, however, are necessary to confirm its effectiveness. Copyright © 2018 by Daedalus Enterprises.

Level set methods for inverse scattering—some recent developments

International Nuclear Information System (INIS)

Dorn, Oliver; Lesselier, Dominique

2009-01-01

We give an update on recent techniques which use a level set representation of shapes for solving inverse scattering problems, completing in that matter the exposition made in (Dorn and Lesselier 2006 Inverse Problems 22 R67) and (Dorn and Lesselier 2007 Deformable Models (New York: Springer) pp 61–90), and bringing it closer to the current state of the art

Global trends in antiretroviral resistance in treatment-naive individuals with HIV after rollout of antiretroviral treatment in resource-limited settings: a global collaborative study and meta-regression analysis

NARCIS (Netherlands)

Gupta, Ravindra K.; Jordan, Michael R.; Sultan, Binta J.; Hill, Andrew; Davis, Daniel H. J.; Gregson, John; Sawyer, Anthony W.; Hamers, Raph L.; Ndembi, Nicaise; Pillay, Deenan; Bertagnolio, Silvia

2012-01-01

Background The emergence and spread of high levels of HIV-1 drug resistance in resource-limited settings where combination antiretroviral treatment has been scaled up could compromise the effectiveness of national HIV treatment programmes. We aimed to estimate changes in the prevalence of HIV-1 drug

Internal Dosimetry Monitoring- Detection Limits for a Selected Set of Radionuclides and Their Translation Into Committed Effective Dose

International Nuclear Information System (INIS)

Brandl, A.; Hrnecek, E.; Steger, F.

2004-01-01

To harmonize the practice of internal dosimetry monitoring across the country, the Austrian Standards Institute is currently drafting a new set of standards which are concerned with occupational incorporation monitoring of individuals handling non-sealed radioactive material. This set of standards is expected to consist of three parts discussing the general necessity and frequency, the requirements for monitoring institutions, and the determination and rigorous calculation of committed effective dose after incorporation of radioactive material, respectively. Considerations of the requirements for routine monitoring laboratories have led to an evaluation of the detection limits for routine monitoring equipment. For a selected set of radionuclides, these detection limits are investigated in detail. The main emphasis is placed on the decay chains of naturally occurring radionuclides showing some significant potential for being out of equilibrium due to chemical processes in certain mining industries. The radionuclides considered in this paper are 226Ra, 228Ra, 228Th, 232Th, 234U, 235U, and 238U. Given the routine monitoring intervals of the Austrian Standard, these detection limits are translated into information on committed effective dose. This paper investigates whether routine monitoring equipment is sufficient to ensure compliance with EC directive 96/29/Euratom for this selected set of radionuclides. (Author) 9 refs

Effect of African- and European-American maternal attitudes and limit-setting strategies on children's self-regulation.

Science.gov (United States)

LeCuyer, Elizabeth A; Swanson, Dena P; Cole, Robert; Kitzman, Harriet

2011-12-01

The effect of maternal attitudes and limit-setting strategies on children's self-regulation (measured as committed compliance) was compared in 151 African-American (AA) and 108 European-American (EA) mothers and their 3-year-old children. There were no ethnic differences in children's compliance, however ethnicity moderated the relationship between maternal authoritarian attitudes and children's compliance. Higher authoritarian attitudes predicted less children's compliance in the EA sample, but greater compliance in the AA sample. Observational limit-setting data revealed that in both ethnic groups, maternal authoritarian attitudes influenced children's self-regulation through maternal use of lower-power (gentle) verbal strategies, fewer physical strategies, and judicious use of higher-power verbal strategies. The findings indicate that the meaning and purpose of authoritarian attitudes varies across these mothers' socio-cultural contexts. Copyright © 2011 Wiley Periodicals, Inc.

Agenda Setting for Health Promotion: Exploring an Adapted Model for the Social Media Era.

Science.gov (United States)

Albalawi, Yousef; Sixsmith, Jane

2015-01-01

The foundation of best practice in health promotion is a robust theoretical base that informs design, implementation, and evaluation of interventions that promote the public's health. This study provides a novel contribution to health promotion through the adaptation of the agenda-setting approach in response to the contribution of social media. This exploration and proposed adaptation is derived from a study that examined the effectiveness of Twitter in influencing agenda setting among users in relation to road traffic accidents in Saudi Arabia. The proposed adaptations to the agenda-setting model to be explored reflect two levels of engagement: agenda setting within the social media sphere and the position of social media within classic agenda setting. This exploratory research aims to assess the veracity of the proposed adaptations on the basis of the hypotheses developed to test these two levels of engagement. To validate the hypotheses, we collected and analyzed data from two primary sources: Twitter activities and Saudi national newspapers. Keyword mentions served as indicators of agenda promotion; for Twitter, interactions were used to measure the process of agenda setting within the platform. The Twitter final dataset comprised 59,046 tweets and 38,066 users who contributed by tweeting, replying, or retweeting. Variables were collected for each tweet and user. In addition, 518 keyword mentions were recorded from six popular Saudi national newspapers. The results showed significant ratification of the study hypotheses at both levels of engagement that framed the proposed adaptions. The results indicate that social media facilitates the contribution of individuals in influencing agendas (individual users accounted for 76.29%, 67.79%, and 96.16% of retweet impressions, total impressions, and amplification multipliers, respectively), a component missing from traditional constructions of agenda-setting models. The influence of organizations on agenda setting is

Agenda Setting for Health Promotion: Exploring an Adapted Model for the Social Media Era

Science.gov (United States)

2015-01-01

Background The foundation of best practice in health promotion is a robust theoretical base that informs design, implementation, and evaluation of interventions that promote the public’s health. This study provides a novel contribution to health promotion through the adaptation of the agenda-setting approach in response to the contribution of social media. This exploration and proposed adaptation is derived from a study that examined the effectiveness of Twitter in influencing agenda setting among users in relation to road traffic accidents in Saudi Arabia. Objective The proposed adaptations to the agenda-setting model to be explored reflect two levels of engagement: agenda setting within the social media sphere and the position of social media within classic agenda setting. This exploratory research aims to assess the veracity of the proposed adaptations on the basis of the hypotheses developed to test these two levels of engagement. Methods To validate the hypotheses, we collected and analyzed data from two primary sources: Twitter activities and Saudi national newspapers. Keyword mentions served as indicators of agenda promotion; for Twitter, interactions were used to measure the process of agenda setting within the platform. The Twitter final dataset comprised 59,046 tweets and 38,066 users who contributed by tweeting, replying, or retweeting. Variables were collected for each tweet and user. In addition, 518 keyword mentions were recorded from six popular Saudi national newspapers. Results The results showed significant ratification of the study hypotheses at both levels of engagement that framed the proposed adaptions. The results indicate that social media facilitates the contribution of individuals in influencing agendas (individual users accounted for 76.29%, 67.79%, and 96.16% of retweet impressions, total impressions, and amplification multipliers, respectively), a component missing from traditional constructions of agenda-setting models. The influence

Laser-Doppler-Velocimetry on the basis of frequency selective absorption: set-up and test of a Doppler Gloval Velocimeter; Laser-Doppler-Velocimetry auf der Basis frequenzselektiver Absorption: Aufbau und Einsatz eines Doppler Global Velocimeters

Energy Technology Data Exchange (ETDEWEB)

Roehle, I.

1999-11-01

A Doppler Global Velocimeter was set up in the frame of a PhD thesis. This velocimeter is optimized to carry out high accuracy, three component, time averaged planar velocity measurements. The anemometer was successfully applied to wind tunnel and test rig flows, and the measurement accuracy was investigated. A volumetric data-set of the flow field inside an industrial combustion chamber was measured. This data field contained about 400.000 vectors. DGV measurements in the intake of a jet engine model were carried out applying a fibre bundle boroskope. The flow structure of the wake of a car model in a wind tunnel was investigated. The measurement accuracy of the DGV-System is {+-}0.5 m/s when operated under ideal conditions. This study can serve as a basis to evaluate the use of DGV for aerodynamic development experiments. (orig.) [German] Im Rahmen der Dissertation wurde ein auf hohe Messgenauigkeit optimiertes DGV-Geraet fuer zeitlich gemittelte Drei-Komponenten-Geschwindigkeitsmessungen entwickelt und gebaut, an Laborstroemungen, an Teststaenden und an Windkanaelen erfolgreich eingesetzt und das Potential der Messtechnik, insbesondere im Hinblick auf Messgenauigkeit, untersucht. Im Fall einer industriellen Brennkammer konnte ein Volumen-Datensatz des Stroemungsfeldes erstellt werden, dessen Umfang bei ca. 400.000 Vektoren lag. Es wurden DGV-Messungen mittels eines flexiblen Endoskops auf Basis eines Faserbuendels durchgefuehrt und damit die Stroemung in einem Flugzeugeinlauf vermessen. Es wurden DGV-Messungen im Nachlauf eines PKW-Modells in einem Windkanal durchgefuehrt. Die Messgenauigkeit des erstellten DGV-Systems betraegt unter Idealbedingungen {+-}0,5 m/s. Durch die Arbeit wurde eine Basis zur Beurteilung des Nutzens der DGV-Technik fuer aerodynamische Entwicklungsarbeiten geschaffen. (orig.)

A level set method for cupping artifact correction in cone-beam CT

International Nuclear Information System (INIS)

Xie, Shipeng; Li, Haibo; Ge, Qi; Li, Chunming

2015-01-01

Purpose: To reduce cupping artifacts and improve the contrast-to-noise ratio in cone-beam computed tomography (CBCT). Methods: A level set method is proposed to reduce cupping artifacts in the reconstructed image of CBCT. The authors derive a local intensity clustering property of the CBCT image and define a local clustering criterion function of the image intensities in a neighborhood of each point. This criterion function defines an energy in terms of the level set functions, which represent a segmentation result and the cupping artifacts. The cupping artifacts are estimated as a result of minimizing this energy. Results: The cupping artifacts in CBCT are reduced by an average of 90%. The results indicate that the level set-based algorithm is practical and effective for reducing the cupping artifacts and preserving the quality of the reconstructed image. Conclusions: The proposed method focuses on the reconstructed image without requiring any additional physical equipment, is easily implemented, and provides cupping correction through a single-scan acquisition. The experimental results demonstrate that the proposed method successfully reduces the cupping artifacts

Level-set simulations of buoyancy-driven motion of single and multiple bubbles

International Nuclear Information System (INIS)

Balcázar, Néstor; Lehmkuhl, Oriol; Jofre, Lluís; Oliva, Assensi

2015-01-01

Highlights: • A conservative level-set method is validated and verified. • An extensive study of buoyancy-driven motion of single bubbles is performed. • The interactions of two spherical and ellipsoidal bubbles is studied. • The interaction of multiple bubbles is simulated in a vertical channel. - Abstract: This paper presents a numerical study of buoyancy-driven motion of single and multiple bubbles by means of the conservative level-set method. First, an extensive study of the hydrodynamics of single bubbles rising in a quiescent liquid is performed, including its shape, terminal velocity, drag coefficients and wake patterns. These results are validated against experimental and numerical data well established in the scientific literature. Then, a further study on the interaction of two spherical and ellipsoidal bubbles is performed for different orientation angles. Finally, the interaction of multiple bubbles is explored in a periodic vertical channel. The results show that the conservative level-set approach can be used for accurate modelling of bubble dynamics. Moreover, it is demonstrated that the present method is numerically stable for a wide range of Morton and Reynolds numbers.

Technical basis document for internal dosimetry

CERN Document Server

Hickman, D P

1991-01-01

This document provides the technical basis for the Chem-Nuclear Geotech (Geotech) internal dosimetry program. Geotech policy describes the intentions of the company in complying with radiation protection standards and the as low as reasonably achievable (ALARA) program. It uses this policy and applicable protection standards to derive acceptable methods and levels of bioassay to assure compliance. The models and computational methods used are described in detail within this document. FR-om these models, dose- conversion factors and derived limits are computed. These computations are then verified using existing documentation and verification information or by demonstration of the calculations used to obtain the dose-conversion factors and derived limits. Recommendations for methods of optimizing the internal dosimetry program to provide effective monitoring and dose assessment for workers are provided in the last section of this document. This document is intended to be used in establishing an accredited dosi...

Vaccination program in a resource-limited setting: A case study in the Philippines.

Science.gov (United States)

Chootipongchaivat, Sarocha; Chantarastapornchit, Varit; Kulpeng, Wantanee; Ceria, Joyce Anne; Tolentino, Niña Isabelle; Teerawattananon, Yot

2016-09-14

Implementing national-level vaccination programs involves long-term investment, which can be a significant financial burden, particularly in resource-limited settings. Although many studies have assessed the economic impacts of providing vaccinations, evidence on the positive and negative implications of human resources for health (HRH) is still lacking. Therefore, this study aims to estimate the HRH impact of introducing pneumococcal conjugate vaccine (PCV) using a model-based economic evaluation. This study adapted a Markov model from a prior study that was conducted in the Philippines for assessing the cost-effectiveness of 10-valent and 13-valent PCV compared to no vaccination. The Markov model was used for estimating the number of cases of pneumococcal-related diseases, categorized by policy options. HRH-related parameters were obtained from document reviews and interviews using the quantity, task, and productivity model (QTP model). The number of full-time equivalent (FTE) of general practitioners, nurses, and midwives increases significantly if the universal vaccine coverage policy is implemented. A universal coverage of PCV13 - which is considered to be the best value for money compared to other vaccination strategies - requires an additional 380 FTEs for general practitioners, 602 FTEs for nurses, and 205 FTEs for midwives; it can reduce the number of FTEs for medical social workers, paediatricians, infectious disease specialists, neurologists, anaesthesiologists, radiologists, ultrasonologists, medical technologists, radiologic technologists, and pharmacists by 7, 17.9, 9.7, 0.4, 0.1, 0.7, 0.1, 12.3, 2, and 9.7, respectively, when compared to the no vaccination policy. This is the first attempt to estimate the impact of HRH alongside a model-based economic evaluation study, which can be eventually applied to other vaccine studies, especially those which inform resource allocation in developing settings where not only financial resources but also HRH are

Threshold limit values, permissible exposure limits, and feasibility: The bases for exposure limits in the United States

International Nuclear Information System (INIS)

Rappaport, S.M.

1993-01-01

The development of exposure limits in the United States has always relied heavily upon the threshold limit values (TLVs) developed by the American Conference of Governmental Industrial Hygienists (ACGIH). In fact, the TLVs were adopted as official exposure limits by the Occupational Safety and Health Administration (OSHA) in 1972 and 1989. Given the continuing importance of the ACGIH limits, this paper compares the basis of the TLVs with that employed by OSHA de novo in its 12 new permissible exposure limits (PELs). Using benzene as an example, it is shown that OSHA's new PELs have been established following a rigorous assessment of the inherent risks and the feasibility of instituting the limit. The TLVs, on the other hand, have been developed by ad hoc procedures and appear to have traditionally reflected levels thought to be achievable at the time. However, this might be changing. Analysis of the historical reductions of TLVs, for 27 substances on the 1991-1992 list of intended changes, indicates smaller reductions in the past (median reduction of 2.0-2.5-fold between 1946 and 1988) compared to those currently being observed (median reduction of 7.5-fold between 1989 and 1991). Further analysis suggests a more aggressive policy of the ACGIH regarding TLVs for carcinogens but not for substances that produce effects other than cancer. Regardless of whether the basis of the TLVs has changed recently, it would take a relatively long time for the impact of any change to be felt, since the median age of the 1991-1992 TLVs is 16.5 years, and 75% of these limits are more than 10 years old. The implications of OSHA's continued reliance on the TLVs as a means of updating its PELs are discussed, and four alternatives are presented to the ACGIH regarding the future of its activities related to exposure limits. It is concluded that new mechanisms are needed for OSHA to update its PELs in a timely fashion so that the TLVs will not be adopted by default in the future

Machine learning (ML)-guided OPC using basis functions of polar Fourier transform

Science.gov (United States)

Choi, Suhyeong; Shim, Seongbo; Shin, Youngsoo

2016-03-01

With shrinking feature size, runtime has become a limitation of model-based OPC (MB-OPC). A few machine learning-guided OPC (ML-OPC) have been studied as candidates for next-generation OPC, but they all employ too many parameters (e.g. local densities), which set their own limitations. We propose to use basis functions of polar Fourier transform (PFT) as parameters of ML-OPC. Since PFT functions are orthogonal each other and well reflect light phenomena, the number of parameters can significantly be reduced without loss of OPC accuracy. Experiments demonstrate that our new ML-OPC achieves 80% reduction in OPC time and 35% reduction in the error of predicted mask bias when compared to conventional ML-OPC.

A Level Set Discontinuous Galerkin Method for Free Surface Flows

DEFF Research Database (Denmark)

Grooss, Jesper; Hesthaven, Jan

2006-01-01

We present a discontinuous Galerkin method on a fully unstructured grid for the modeling of unsteady incompressible fluid flows with free surfaces. The surface is modeled by embedding and represented by a levelset. We discuss the discretization of the flow equations and the level set equation...

Priority setting at the micro-, meso- and macro-levels in Canada, Norway and Uganda.

Science.gov (United States)

Kapiriri, Lydia; Norheim, Ole Frithjof; Martin, Douglas K

2007-06-01

The objectives of this study were (1) to describe the process of healthcare priority setting in Ontario-Canada, Norway and Uganda at the three levels of decision-making; (2) to evaluate the description using the framework for fair priority setting, accountability for reasonableness; so as to identify lessons of good practices. We carried out case studies involving key informant interviews, with 184 health practitioners and health planners from the macro-level, meso-level and micro-level from Canada-Ontario, Norway and Uganda (selected by virtue of their varying experiences in priority setting). Interviews were audio-recorded, transcribed and analyzed using a modified thematic approach. The descriptions were evaluated against the four conditions of "accountability for reasonableness", relevance, publicity, revisions and enforcement. Areas of adherence to these conditions were identified as lessons of good practices; areas of non-adherence were identified as opportunities for improvement. (i) at the macro-level, in all three countries, cabinet makes most of the macro-level resource allocation decisions and they are influenced by politics, public pressure, and advocacy. Decisions within the ministries of health are based on objective formulae and evidence. International priorities influenced decisions in Uganda. Some priority-setting reasons are publicized through circulars, printed documents and the Internet in Canada and Norway. At the meso-level, hospital priority-setting decisions were made by the hospital managers and were based on national priorities, guidelines, and evidence. Hospital departments that handle emergencies, such as surgery, were prioritized. Some of the reasons are available on the hospital intranet or presented at meetings. Micro-level practitioners considered medical and social worth criteria. These reasons are not publicized. Many practitioners lacked knowledge of the macro- and meso-level priority-setting processes. (ii) Evaluation

Embedded Real-Time Architecture for Level-Set-Based Active Contours

Directory of Open Access Journals (Sweden)

Dejnožková Eva

2005-01-01

Full Text Available Methods described by partial differential equations have gained a considerable interest because of undoubtful advantages such as an easy mathematical description of the underlying physics phenomena, subpixel precision, isotropy, or direct extension to higher dimensions. Though their implementation within the level set framework offers other interesting advantages, their vast industrial deployment on embedded systems is slowed down by their considerable computational effort. This paper exploits the high parallelization potential of the operators from the level set framework and proposes a scalable, asynchronous, multiprocessor platform suitable for system-on-chip solutions. We concentrate on obtaining real-time execution capabilities. The performance is evaluated on a continuous watershed and an object-tracking application based on a simple gradient-based attraction force driving the active countour. The proposed architecture can be realized on commercially available FPGAs. It is built around general-purpose processor cores, and can run code developed with usual tools.

Formation of organic aerosol in the Paris region during the MEGAPOLI summer campaign: evaluation of the volatility-basis-set approach within the CHIMERE model

Directory of Open Access Journals (Sweden)

Q. J. Zhang

2013-06-01

Full Text Available Simulations with the chemistry transport model CHIMERE are compared to measurements performed during the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric POLlution and climate effects, and Integrated tools for assessment and mitigation summer campaign in the Greater Paris region in July 2009. The volatility-basis-set approach (VBS is implemented into this model, taking into account the volatility of primary organic aerosol (POA and the chemical aging of semi-volatile organic species. Organic aerosol is the main focus and is simulated with three different configurations with a modified treatment of POA volatility and modified secondary organic aerosol (SOA formation schemes. In addition, two types of emission inventories are used as model input in order to test the uncertainty related to the emissions. Predictions of basic meteorological parameters and primary and secondary pollutant concentrations are evaluated, and four pollution regimes are defined according to the air mass origin. Primary pollutants are generally overestimated, while ozone is consistent with observations. Sulfate is generally overestimated, while ammonium and nitrate levels are well simulated with the refined emission data set. As expected, the simulation with non-volatile POA and a single-step SOA formation mechanism largely overestimates POA and underestimates SOA. Simulation of organic aerosol with the VBS approach taking into account the aging of semi-volatile organic compounds (SVOC shows the best correlation with measurements. High-concentration events observed mostly after long-range transport are well reproduced by the model. Depending on the emission inventory used, simulated POA levels are either reasonable or underestimated, while SOA levels tend to be overestimated. Several uncertainties related to the VBS scheme (POA volatility, SOA yields, the aging parameterization, to emission input data, and to simulated OH levels can be responsible for

Numerical Modelling of Three-Fluid Flow Using The Level-set Method

Science.gov (United States)

Li, Hongying; Lou, Jing; Shang, Zhi

2014-11-01

This work presents a numerical model for simulation of three-fluid flow involving two different moving interfaces. These interfaces are captured using the level-set method via two different level-set functions. A combined formulation with only one set of conservation equations for the whole physical domain, consisting of the three different immiscible fluids, is employed. Numerical solution is performed on a fixed mesh using the finite volume method. Surface tension effect is incorporated using the Continuum Surface Force model. Validation of the present model is made against available results for stratified flow and rising bubble in a container with a free surface. Applications of the present model are demonstrated by a variety of three-fluid flow systems including (1) three-fluid stratified flow, (2) two-fluid stratified flow carrying the third fluid in the form of drops and (3) simultaneous rising and settling of two drops in a stationary third fluid. The work is supported by a Thematic and Strategic Research from A*STAR, Singapore (Ref. #: 1021640075).

Validation of a pediatric early warning system for hospitalized pediatric oncology patients in a resource-limited setting.

Science.gov (United States)

Agulnik, Asya; Méndez Aceituno, Alejandra; Mora Robles, Lupe Nataly; Forbes, Peter W; Soberanis Vasquez, Dora Judith; Mack, Ricardo; Antillon-Klussmann, Federico; Kleinman, Monica; Rodriguez-Galindo, Carlos

2017-12-15

Pediatric oncology patients are at high risk of clinical deterioration, particularly in hospitals with resource limitations. The performance of pediatric early warning systems (PEWS) to identify deterioration has not been assessed in these settings. This study evaluates the validity of PEWS to predict the need for unplanned transfer to the pediatric intensive care unit (PICU) among pediatric oncology patients in a resource-limited hospital. A retrospective case-control study comparing the highest documented and corrected PEWS score before unplanned PICU transfer in pediatric oncology patients (129 cases) with matched controls (those not requiring PICU care) was performed. Documented and corrected PEWS scores were found to be highly correlated with the need for PICU transfer (area under the receiver operating characteristic, 0.940 and 0.930, respectively). PEWS scores increased 24 hours prior to unplanned transfer (P = .0006). In cases, organ dysfunction at the time of PICU admission correlated with maximum PEWS score (correlation coefficient, 0.26; P = .003), patients with PEWS results ≥4 had a higher Pediatric Index of Mortality 2 (PIM2) (P = .028), and PEWS results were higher in patients with septic shock (P = .01). The PICU mortality rate was 17.1%; nonsurvivors had higher mean PEWS scores before PICU transfer (P = .0009). A single-point increase in the PEWS score increased the odds of mechanical ventilation or vasopressors within the first 24 hours and during PICU admission (odds ratio 1.3-1.4). PEWS accurately predicted the need for unplanned PICU transfer in pediatric oncology patients in this resource-limited setting, with abnormal results beginning 24 hours before PICU admission and higher scores predicting the severity of illness at the time of PICU admission, need for PICU interventions, and mortality. These results demonstrate that PEWS aid in the identification of clinical deterioration in this high-risk population, regardless of a hospital

Use of 90% ethanol to decontaminate stethoscopes in resource limited settings

Directory of Open Access Journals (Sweden)

Bijendra Raj Raghubanshi

2017-06-01

Full Text Available Abstract Background In developing countries like Nepal, 90% ethanol is cheap and is available in most hospitals. The unavailability of isopropyl alcohol (IPA in these settings led us to compare the efficacy between 90% ethanol and isopropyl alcohol pads in reducing the bacterial contamination of diaphragm of stethoscope. Methods A randomized blinded experimental study was carried out to determine the difference between cleaning stethoscopes with 90% ethanol and IPA. Cultures of diaphragm were taken before and after cleaning with one of the cleaning agent. Colony forming units (CFU count and organism identification was done by a blinded investigator. CFU before and after cleaning were compared using Wilcoxon signed–rank test. Mann Whitney U test was used to compare the decrease in CFU count between the cleaning agents. Results About 30% of the stethoscopes harbored potential pathogens. Significant reduction in CFU was observed with both IPA (Wilcoxon signed–rank test, P value 0.05. Conclusions Both 90% ethanol and IPA are equally effective in decontaminating the diaphragm of stethoscope. Selection of agent should be done on the basis of cost and availability.

Use of 90% ethanol to decontaminate stethoscopes in resource limited settings.

Science.gov (United States)

Raghubanshi, Bijendra Raj; Sapkota, Supriya; Adhikari, Arjab; Dutta, Aman; Bhattarai, Utsuk; Bhandari, Rastriyata

2017-01-01

In developing countries like Nepal, 90% ethanol is cheap and is available in most hospitals. The unavailability of isopropyl alcohol (IPA) in these settings led us to compare the efficacy between 90% ethanol and isopropyl alcohol pads in reducing the bacterial contamination of diaphragm of stethoscope. A randomized blinded experimental study was carried out to determine the difference between cleaning stethoscopes with 90% ethanol and IPA. Cultures of diaphragm were taken before and after cleaning with one of the cleaning agent. Colony forming units (CFU) count and organism identification was done by a blinded investigator. CFU before and after cleaning were compared using Wilcoxon signed-rank test. Mann Whitney U test was used to compare the decrease in CFU count between the cleaning agents. About 30% of the stethoscopes harbored potential pathogens. Significant reduction in CFU was observed with both IPA (Wilcoxon signed-rank test, P value Wilcoxon signed-rank test, P value test; U = 1357, P value >0.05). Both 90% ethanol and IPA are equally effective in decontaminating the diaphragm of stethoscope. Selection of agent should be done on the basis of cost and availability.

A quantum molecular similarity analysis of changes in molecular electron density caused by basis set flotation and electric field application

Science.gov (United States)

Simon, Sílvia; Duran, Miquel

1997-08-01

Quantum molecular similarity (QMS) techniques are used to assess the response of the electron density of various small molecules to application of a static, uniform electric field. Likewise, QMS is used to analyze the changes in electron density generated by the process of floating a basis set. The results obtained show an interrelation between the floating process, the optimum geometry, and the presence of an external field. Cases involving the Le Chatelier principle are discussed, and an insight on the changes of bond critical point properties, self-similarity values and density differences is performed.

A set of nutrient limitations trigger yeast cell death in a nitrogen-dependent manner during wine alcoholic fermentation.

Directory of Open Access Journals (Sweden)

Camille Duc

Full Text Available Yeast cell death can occur during wine alcoholic fermentation. It is generally considered to result from ethanol stress that impacts membrane integrity. This cell death mainly occurs when grape musts processing reduces lipid availability, resulting in weaker membrane resistance to ethanol. However the mechanisms underlying cell death in these conditions remain unclear. We examined cell death occurrence considering yeast cells ability to elicit an appropriate response to a given nutrient limitation and thus survive starvation. We show here that a set of micronutrients (oleic acid, ergosterol, pantothenic acid and nicotinic acid in low, growth-restricting concentrations trigger cell death in alcoholic fermentation when nitrogen level is high. We provide evidence that nitrogen signaling is involved in cell death and that either SCH9 deletion or Tor inhibition prevent cell death in several types of micronutrient limitation. Under such limitations, yeast cells fail to acquire any stress resistance and are unable to store glycogen. Unexpectedly, transcriptome analyses did not reveal any major changes in stress genes expression, suggesting that post-transcriptional events critical for stress response were not triggered by micronutrient starvation. Our data point to the fact that yeast cell death results from yeast inability to trigger an appropriate stress response under some conditions of nutrient limitations most likely not encountered by yeast in the wild. Our conclusions provide a novel frame for considering both cell death and the management of nutrients during alcoholic fermentation.

Simplification of antiretroviral therapy: a necessary step in the public health response to HIV/AIDS in resource-limited settings.

Science.gov (United States)

Vitoria, Marco; Ford, Nathan; Doherty, Meg; Flexner, Charles

2014-01-01

The global scale-up of antiretroviral therapy (ART) over the past decade represents one of the great public health and human rights achievements of recent times. Moving from an individualized treatment approach to a simplified and standardized public health approach has been critical to ART scale-up, simplifying both prescribing practices and supply chain management. In terms of the latter, the risk of stock-outs can be reduced and simplified prescribing practices support task shifting of care to nursing and other non-physician clinicians; this strategy is critical to increase access to ART care in settings where physicians are limited in number. In order to support such simplification, successive World Health Organization guidelines for ART in resource-limited settings have aimed to reduce the number of recommended options for first-line ART in such settings. Future drug and regimen choices for resource-limited settings will likely be guided by the same principles that have led to the recommendation of a single preferred regimen and will favour drugs that have the following characteristics: minimal risk of failure, efficacy and tolerability, robustness and forgiveness, no overlapping resistance in treatment sequencing, convenience, affordability, and compatibility with anti-TB and anti-hepatitis treatments.

Challenges in the implementation of an electronic surveillance system in a resource-limited setting: Alerta, in Peru

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Soto Giselle

2008-11-01

Full Text Available Abstract Background Infectious disease surveillance is a primary public health function in resource-limited settings. In 2003, an electronic disease surveillance system (Alerta was established in the Peruvian Navy with support from the U.S. Naval Medical Research Center Detachment (NMRCD. Many challenges arose during the implementation process, and a variety of solutions were applied. The purpose of this paper is to identify and discuss these issues. Methods This is a retrospective description of the Alerta implementation. After a thoughtful evaluation according to the Centers for Disease Control and Prevention (CDC guidelines, the main challenges to implementation were identified and solutions were devised in the context of a resource-limited setting, Peru. Results After four years of operation, we have identified a number of challenges in implementing and operating this electronic disease surveillance system. These can be divided into the following categories: (1 issues with personnel and stakeholders; (2 issues with resources in a developing setting; (3 issues with processes involved in the collection of data and operation of the system; and (4 issues with organization at the central hub. Some of the challenges are unique to resource-limited settings, but many are applicable for any surveillance system. For each of these challenges, we developed feasible solutions that are discussed. Conclusion There are many challenges to overcome when implementing an electronic disease surveillance system, not only related to technology issues. A comprehensive approach is required for success, including: technical support, personnel management, effective training, and cultural sensitivity in order to assure the effective deployment of an electronic disease surveillance system.

Level set method for image segmentation based on moment competition

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Min, Hai; Wang, Xiao-Feng; Huang, De-Shuang; Jin, Jing; Wang, Hong-Zhi; Li, Hai

2015-05-01

We propose a level set method for image segmentation which introduces the moment competition and weakly supervised information into the energy functional construction. Different from the region-based level set methods which use force competition, the moment competition is adopted to drive the contour evolution. Here, a so-called three-point labeling scheme is proposed to manually label three independent points (weakly supervised information) on the image. Then the intensity differences between the three points and the unlabeled pixels are used to construct the force arms for each image pixel. The corresponding force is generated from the global statistical information of a region-based method and weighted by the force arm. As a result, the moment can be constructed and incorporated into the energy functional to drive the evolving contour to approach the object boundary. In our method, the force arm can take full advantage of the three-point labeling scheme to constrain the moment competition. Additionally, the global statistical information and weakly supervised information are successfully integrated, which makes the proposed method more robust than traditional methods for initial contour placement and parameter setting. Experimental results with performance analysis also show the superiority of the proposed method on segmenting different types of complicated images, such as noisy images, three-phase images, images with intensity inhomogeneity, and texture images.

Topological Hausdorff dimension and level sets of generic continuous functions on fractals

International Nuclear Information System (INIS)

Balka, Richárd; Buczolich, Zoltán; Elekes, Márton

2012-01-01

Highlights: ► We examine a new fractal dimension, the so called topological Hausdorff dimension. ► The generic continuous function has a level set of maximal Hausdorff dimension. ► This maximal dimension is the topological Hausdorff dimension minus one. ► Homogeneity implies that “most” level sets are of this dimension. ► We calculate the various dimensions of the graph of the generic function. - Abstract: In an earlier paper we introduced a new concept of dimension for metric spaces, the so called topological Hausdorff dimension. For a compact metric space K let dim H K and dim tH K denote its Hausdorff and topological Hausdorff dimension, respectively. We proved that this new dimension describes the Hausdorff dimension of the level sets of the generic continuous function on K, namely sup{ dim H f -1 (y):y∈R} =dim tH K-1 for the generic f ∈ C(K), provided that K is not totally disconnected, otherwise every non-empty level set is a singleton. We also proved that if K is not totally disconnected and sufficiently homogeneous then dim H f −1 (y) = dim tH K − 1 for the generic f ∈ C(K) and the generic y ∈ f(K). The most important goal of this paper is to make these theorems more precise. As for the first result, we prove that the supremum is actually attained on the left hand side of the first equation above, and also show that there may only be a unique level set of maximal Hausdorff dimension. As for the second result, we characterize those compact metric spaces for which for the generic f ∈ C(K) and the generic y ∈ f(K) we have dim H f −1 (y) = dim tH K − 1. We also generalize a result of B. Kirchheim by showing that if K is self-similar then for the generic f ∈ C(K) for every y∈intf(K) we have dim H f −1 (y) = dim tH K − 1. Finally, we prove that the graph of the generic f ∈ C(K) has the same Hausdorff and topological Hausdorff dimension as K.

No evidence for an item limit in change detection.

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Shaiyan Keshvari

Full Text Available Change detection is a classic paradigm that has been used for decades to argue that working memory can hold no more than a fixed number of items ("item-limit models". Recent findings force us to consider the alternative view that working memory is limited by the precision in stimulus encoding, with mean precision decreasing with increasing set size ("continuous-resource models". Most previous studies that used the change detection paradigm have ignored effects of limited encoding precision by using highly discriminable stimuli and only large changes. We conducted two change detection experiments (orientation and color in which change magnitudes were drawn from a wide range, including small changes. In a rigorous comparison of five models, we found no evidence of an item limit. Instead, human change detection performance was best explained by a continuous-resource model in which encoding precision is variable across items and trials even at a given set size. This model accounts for comparison errors in a principled, probabilistic manner. Our findings sharply challenge the theoretical basis for most neural studies of working memory capacity.

Relationships between college settings and student alcohol use before, during and after events: a multi-level study.

Science.gov (United States)

Paschall, Mallie J; Saltz, Robert F

2007-11-01

We examined how alcohol risk is distributed based on college students' drinking before, during and after they go to certain settings. Students attending 14 California public universities (N=10,152) completed a web-based or mailed survey in the fall 2003 semester, which included questions about how many drinks they consumed before, during and after the last time they went to six settings/events: fraternity or sorority party, residence hall party, campus event (e.g. football game), off-campus party, bar/restaurant and outdoor setting (referent). Multi-level analyses were conducted in hierarchical linear modeling (HLM) to examine relationships between type of setting and level of alcohol use before, during and after going to the setting, and possible age and gender differences in these relationships. Drinking episodes (N=24,207) were level 1 units, students were level 2 units and colleges were level 3 units. The highest drinking levels were observed during all settings/events except campus events, with the highest number of drinks being consumed at off-campus parties, followed by residence hall and fraternity/sorority parties. The number of drinks consumed before a fraternity/sorority party was higher than other settings/events. Age group and gender differences in relationships between type of setting/event and 'before,''during' and 'after' drinking levels also were observed. For example, going to a bar/restaurant (relative to an outdoor setting) was positively associated with 'during' drinks among students of legal drinking age while no relationship was observed for underage students. Findings of this study indicate differences in the extent to which college settings are associated with student drinking levels before, during and after related events, and may have implications for intervention strategies targeting different types of settings.

Individual-and Setting-Level Correlates of Secondary Traumatic Stress in Rape Crisis Center Staff.

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Dworkin, Emily R; Sorell, Nicole R; Allen, Nicole E

2016-02-01

Secondary traumatic stress (STS) is an issue of significant concern among providers who work with survivors of sexual assault. Although STS has been studied in relation to individual-level characteristics of a variety of types of trauma responders, less research has focused specifically on rape crisis centers as environments that might convey risk or protection from STS, and no research to knowledge has modeled setting-level variation in correlates of STS. The current study uses a sample of 164 staff members representing 40 rape crisis centers across a single Midwestern state to investigate the staff member-and agency-level correlates of STS. Results suggest that correlates exist at both levels of analysis. Younger age and greater severity of sexual assault history were statistically significant individual-level predictors of increased STS. Greater frequency of supervision was more strongly related to secondary stress for non-advocates than for advocates. At the setting level, lower levels of supervision and higher client loads agency-wide accounted for unique variance in staff members' STS. These findings suggest that characteristics of both providers and their settings are important to consider when understanding their STS. © The Author(s) 2014.

Electronic structure of crystalline uranium nitrides UN, U{sub 2}N{sub 3} and UN{sub 2}: LCAO calculations with the basis set optimization

Energy Technology Data Exchange (ETDEWEB)

Evarestov, R A; Panin, A I; Bandura, A V; Losev, M V [Department of Quantum Chemistry, St. Petersburg State University, University Prospect 26, Stary Peterghof, St. Petersburg, 198504 (Russian Federation)], E-mail: re1973@re1973.spb.edu

2008-06-01

The results of LCAO DFT calculations of lattice parameters, cohesive energy and bulk modulus of the crystalline uranium nitrides UN, U{sub 2}N{sub 3} and UN{sub 2} are presented and discussed. The LCAO computer codes Gaussian03 and Crystal06 are applied. The calculations are made with the uranium atom relativistic effective small core potential by Stuttgart-Cologne group (60 electrons in the core). The calculations include the U atom basis set optimization. Powell, Hooke-Jeeves, conjugated gradient and Box methods are implemented in the author's optimization package, being external to the codes for molecular and periodic calculations. The basis set optimization in LCAO calculations improves the agreement of the lattice parameter and bulk modulus of UN crystal with the experimental data, the change of the cohesive energy due to the optimization is small. The mixed metallic-covalent chemical bonding is found both in LCAO calculations of UN and U{sub 2}N{sub 3} crystals; UN{sub 2} crystal has the semiconducting nature.

Design and analysis of the TFTR fixed limiters - 1

International Nuclear Information System (INIS)

Winkler, P.; Fixler, S.; Timlen, W.V.

1981-01-01

The operation of the Tokamak Fusion Test Reactor (TFTR) consists of two phases. In the first phase, the Tokamak systems will be tested and an ohmic heated plasma of 4 MW produced. The plasma limiter system for this phase consists of a set of movable and a set of fixed limiters. Because of the low power level during this phase, a design of passively cooled fixed limiters without tiles will satisfy the requirements. This limiter will be replaced by an actively cooled tile-covered axisymmetric limiter in the second phase. This paper discusses the design of the first phase fixed limiters only

Geological basis and data set for assessing the long-term safety of the final repository for low- and intermediate-level radioactive wastes at the Wellenberg site (Community of Wolfenschiessen, NW)

International Nuclear Information System (INIS)

1993-09-01

This report forms part of the supporting documentation for the low- and intermediate-level waste repository site selection procedure. The aim of the report is to present the site-specific geological data, and the geosphere database derived therefrom, which were used as a basis for evaluating the long-term safety of a repository at Wellenberg. These data also form a key component of other reports appearing simultaneously with the present one, first on the intercomparison of the four potential sites, (NTB 93-02) and second, on the safety assessment of the Wellenberg site itself (NTB 93-26). The level of detail of the present report is determined by the requirements of the other two reports mentioned, which would include presenting, discussing and justifying the geosphere dataset used in the performance assessment model calculations. The introductory chapter discusses procedures and goals. The second chapter provides an overview of the geographical and geological situation at Wellenberg. Chapter 3 then discusses the planning and progress of the field programme, and the current status of investigations is presented. The fourth chapter presents the geological situation at the Wellenberg site and describes the concept and models formulated on the basis of this information. Chapter 5 derives the performance assessment and engineering datasets, based on the investigations, concepts and modelling exercises described in chapter 4. In summary, it can be said that, to date, the investigation results from Wellenberg have confirmed predictions in all relevant respects and, in some cases, have even exceeded expectations (e.g. in relation to the available volume of host rock). (author) figs., tabs., 141 refs

Limited capacity for contour curvature in iconic memory.

Science.gov (United States)

Sakai, Koji

2006-06-01

We measured the difference threshold for contour curvature in iconic memory by using the cued discrimination method. The study stimulus consisting of 2 to 6 curved contours was briefly presented in the fovea, followed by two lines as cues. Subjects discriminated the curvature of two cued curves. The cue delays were 0 msec. and 300 msec. in Exps. 1 and 2, respectively, and 50 msec. before the study offset in Exp. 3. Analysis of data from Exps. 1 and 2 showed that the Weber fraction rose monotonically with the increase in set size. Clear set-size effects indicate that iconic memory has a limited capacity. Moreover, clear set-size effect in Exp. 3 indicates that perception itself has a limited capacity. Larger set-size effects in Exp. 1 than in Exp. 3 suggest that iconic memory after perceptual process has limited capacity. These properties of iconic memory at threshold level are contradictory to the traditional view that iconic memory has a high capacity both at suprathreshold and categorical levels.

Hybrid approach for detection of dental caries based on the methods FCM and level sets

Science.gov (United States)

Chaabene, Marwa; Ben Ali, Ramzi; Ejbali, Ridha; Zaied, Mourad

2017-03-01

This paper presents a new technique for detection of dental caries that is a bacterial disease that destroys the tooth structure. In our approach, we have achieved a new segmentation method that combines the advantages of fuzzy C mean algorithm and level set method. The results obtained by the FCM algorithm will be used by Level sets algorithm to reduce the influence of the noise effect on the working of each of these algorithms, to facilitate level sets manipulation and to lead to more robust segmentation. The sensitivity and specificity confirm the effectiveness of proposed method for caries detection.

Fluoroscopy-guided insertion of nasojejunal tubes in children - setting local diagnostic reference levels

International Nuclear Information System (INIS)

Vitta, Lavanya; Raghavan, Ashok; Sprigg, Alan; Morrell, Rachel

2009-01-01

Little is known about the radiation burden from fluoroscopy-guided insertions of nasojejunal tubes (NJTs) in children. There are no recommended or published standards of diagnostic reference levels (DRLs) available. To establish reference dose area product (DAP) levels for the fluoroscopy-guided insertion of nasojejunal tubes as a basis for setting DRLs for children. In addition, we wanted to assess our local practice and determine the success and complication rates associated with this procedure. Children who had NJT insertion procedures were identified retrospectively from the fluoroscopy database. The age of the child at the time of the procedure, DAP, screening time, outcome of the procedure, and any complications were recorded for each procedure. As the radiation dose depends on the size of the child, the children were assigned to three different age groups. The sample size, mean, median and third-quartile DAPs were calculated for each group. The third-quartile values were used to establish the DRLs. Of 186 procedures performed, 172 were successful on the first attempt. These were performed in a total of 43 children with 60% having multiple insertions over time. The third-quartile DAPs were as follows for each age group: 0-12 months, 2.6 cGy cm 2 ; 1-7 years, 2.45 cGy cm 2 ; >8 years, 14.6 cGy cm 2 . High DAP readings were obtained in the 0-12 months (n = 4) and >8 years (n = 2) age groups. No immediate complications were recorded. Fluoroscopy-guided insertion of NJTs is a highly successful procedure in a selected population of children and is associated with a low complication rate. The radiation dose per procedure is relatively low. (orig.)

Technical meeting on progress in managing, and limiting the consequences of events exceeding the design basis

International Nuclear Information System (INIS)

Fabian, H.

2004-01-01

The Technical Groups on 'Reactor Safety' and 'Thermodynamics and Fluid Dynamics' of the Kerntechnische Gesellschaft e.V. organized a joint technical meeting on 'Progress in Managing, and Limiting the Consequences of, Events Exceeding the Design Basis' at the FTU Training Center of the Karlsruhe Research Center. The topic chosen, the papers presented, the presenters, and the non-technical part of the program met with lively interest on the part of institutions in the nuclear field. These were the objectives of the technical meeting: - Establishing a forum for communicating relevant topics. - In-depth discussion of the main topic, i.e. the advanced development of reactor safety, research in the field, and its application, in twenty selected papers presented by speakers from different institutions. - Presentation of topical work in a nuclear technology institution, the Karlsruhe Research Center. (orig.) [de

Density functional theory study of the interaction of vinyl radical, ethyne, and ethene with benzene, aimed to define an affordable computational level to investigate stability trends in large van der Waals complexes

Science.gov (United States)

Maranzana, Andrea; Giordana, Anna; Indarto, Antonius; Tonachini, Glauco; Barone, Vincenzo; Causà, Mauro; Pavone, Michele

2013-12-01

Our purpose is to identify a computational level sufficiently dependable and affordable to assess trends in the interaction of a variety of radical or closed shell unsaturated hydro-carbons A adsorbed on soot platelet models B. These systems, of environmental interest, would unavoidably have rather large sizes, thus prompting to explore in this paper the performances of relatively low-level computational methods and compare them with higher-level reference results. To this end, the interaction of three complexes between non-polar species, vinyl radical, ethyne, or ethene (A) with benzene (B) is studied, since these species, involved themselves in growth processes of polycyclic aromatic hydrocarbons (PAHs) and soot particles, are small enough to allow high-level reference calculations of the interaction energy ΔEAB. Counterpoise-corrected interaction energies ΔEAB are used at all stages. (1) Density Functional Theory (DFT) unconstrained optimizations of the A-B complexes are carried out, using the B3LYP-D, ωB97X-D, and M06-2X functionals, with six basis sets: 6-31G(d), 6-311 (2d,p), and 6-311++G(3df,3pd); aug-cc-pVDZ and aug-cc-pVTZ; N07T. (2) Then, unconstrained optimizations by Møller-Plesset second order Perturbation Theory (MP2), with each basis set, allow subsequent single point Coupled Cluster Singles Doubles and perturbative estimate of the Triples energy computations with the same basis sets [CCSD(T)//MP2]. (3) Based on an additivity assumption of (i) the estimated MP2 energy at the complete basis set limit [EMP2/CBS] and (ii) the higher-order correlation energy effects in passing from MP2 to CCSD(T) at the aug-cc-pVTZ basis set, ΔECC-MP, a CCSD(T)/CBS estimate is obtained and taken as a computational energy reference. At DFT, variations in ΔEAB with basis set are not large for the title molecules, and the three functionals perform rather satisfactorily even with rather small basis sets [6-31G(d) and N07T], exhibiting deviation from the computational

Density functional theory study of the interaction of vinyl radical, ethyne, and ethene with benzene, aimed to define an affordable computational level to investigate stability trends in large van der Waals complexes

International Nuclear Information System (INIS)

Maranzana, Andrea; Giordana, Anna; Indarto, Antonius; Tonachini, Glauco; Barone, Vincenzo; Causà, Mauro; Pavone, Michele

2013-01-01

Our purpose is to identify a computational level sufficiently dependable and affordable to assess trends in the interaction of a variety of radical or closed shell unsaturated hydro-carbons A adsorbed on soot platelet models B. These systems, of environmental interest, would unavoidably have rather large sizes, thus prompting to explore in this paper the performances of relatively low-level computational methods and compare them with higher-level reference results. To this end, the interaction of three complexes between non-polar species, vinyl radical, ethyne, or ethene (A) with benzene (B) is studied, since these species, involved themselves in growth processes of polycyclic aromatic hydrocarbons (PAHs) and soot particles, are small enough to allow high-level reference calculations of the interaction energy ΔE AB . Counterpoise-corrected interaction energies ΔE AB are used at all stages. (1) Density Functional Theory (DFT) unconstrained optimizations of the A−B complexes are carried out, using the B3LYP-D, ωB97X-D, and M06-2X functionals, with six basis sets: 6-31G(d), 6-311 (2d,p), and 6-311++G(3df,3pd); aug-cc-pVDZ and aug-cc-pVTZ; N07T. (2) Then, unconstrained optimizations by Møller-Plesset second order Perturbation Theory (MP2), with each basis set, allow subsequent single point Coupled Cluster Singles Doubles and perturbative estimate of the Triples energy computations with the same basis sets [CCSD(T)//MP2]. (3) Based on an additivity assumption of (i) the estimated MP2 energy at the complete basis set limit [E MP2/CBS ] and (ii) the higher-order correlation energy effects in passing from MP2 to CCSD(T) at the aug-cc-pVTZ basis set, ΔE CC-MP , a CCSD(T)/CBS estimate is obtained and taken as a computational energy reference. At DFT, variations in ΔE AB with basis set are not large for the title molecules, and the three functionals perform rather satisfactorily even with rather small basis sets [6-31G(d) and N07T], exhibiting deviation from the

Caring for the injured child in settings of limited resource.

Science.gov (United States)

Stephenson, Jacob

2016-02-01

Children represent the most vulnerable members of our global society, a truth that is magnified when they are physically wounded. In much of the developed world, society has responded by offering protection in the form of law, injury prevention guidelines, and effective trauma systems to provide care for the injured child. Much of our world, though, remains afflicted by poverty and a lack of protective measures. As the globe becomes smaller by way of ease of travel and technology, surgeons are increasingly able to meet these children where they live and in doing so offer their hands and voices to care and protect these young ones. This article is intended as an overview of current issues in pediatric trauma care in the developing world as well as to offer some tips for the volunteer surgeon who may be involved in the care of the injured child in a setting of limited resource availability. Published by Elsevier Inc.

Understanding and capturing NSSS design basis

International Nuclear Information System (INIS)

Palo, W.J.; Miller, B.

1993-01-01

Changes to, and technical evaluations of nuclear generating station designs are often warranted. Comprehensive documentation and understanding of the NSSS Design Basis are essential to support these activities. Effective configuration management tools are also needed to maintain the plant within design basis limits. Efficient design basis reconstitution can be realized via: In-depth understanding of the design process; Utilization of effective data collection methodology; State of the art data basing tools. A database can be created to generate a Design Basis Manual (DBM). This database can communicate electronically with other plant databases. A living document vice a static snapshot of the plant design is the goal. A design basis database can serve as the cornerstone for a global electronic information control system

Economic communication model set

Science.gov (United States)

Zvereva, Olga M.; Berg, Dmitry B.

2017-06-01

This paper details findings from the research work targeted at economic communications investigation with agent-based models usage. The agent-based model set was engineered to simulate economic communications. Money in the form of internal and external currencies was introduced into the models to support exchanges in communications. Every model, being based on the general concept, has its own peculiarities in algorithm and input data set since it was engineered to solve the specific problem. Several and different origin data sets were used in experiments: theoretic sets were estimated on the basis of static Leontief's equilibrium equation and the real set was constructed on the basis of statistical data. While simulation experiments, communication process was observed in dynamics, and system macroparameters were estimated. This research approved that combination of an agent-based and mathematical model can cause a synergetic effect.

Limited oxygen index levels of impregnated Scots pine wood

International Nuclear Information System (INIS)

Tomak, Eylem Dizman; Cavdar, Ayfer Donmez

2013-01-01

Highlights: • Scots pine samples were treated with 4 wood preservatives with various concentrations. • Limited oxygen index level was evaluated both for leached and un-leached samples. • All treatments improved fire retardance of samples despite some chemicals leached out. • Samples treated with fireproof agent showed the best results. • LOI of samples treated with boron powder and silicon oil was not changed by leaching. - Abstract: In this study, effect of various concentrations of boron powder, mixture of boric acid and borax, fireproof agent based on liquid blend of limestone, and silicon oil on limited oxygen index levels (LOI) of S. pine wood was investigated. Wood samples were first vacuum treated with the preservatives, and then were subjected to leaching procedure. Samples treated with fireproof agent showed the best results for improving the fire retardancy of wood, furthermore, samples treated with 25%, 50% and 100% of the solution did not burn. Leaching did not considerably change the LOI of wood samples treated with boron powder and silicon oil; however, LOI levels of samples treated with the mixture of boric acid and borax and fireproof agent were affected by leaching procedure probably arising those preservatives did not chemically bond to main wood components. All treatments improved fire retardancy of samples despite some amount of preservatives leached out from wood

Limited oxygen index levels of impregnated Scots pine wood

Energy Technology Data Exchange (ETDEWEB)

Tomak, Eylem Dizman, E-mail: eylemdizman@yahoo.com [Forest Industry Engineering Department, Faculty of Forestry, Bursa Technical University, 16200 Bursa (Turkey); Cavdar, Ayfer Donmez [Interior Architecture Department, Faculty of Architecture, Karadeniz Technical University, 61080 Trabzon (Turkey)

2013-12-10

Highlights: • Scots pine samples were treated with 4 wood preservatives with various concentrations. • Limited oxygen index level was evaluated both for leached and un-leached samples. • All treatments improved fire retardance of samples despite some chemicals leached out. • Samples treated with fireproof agent showed the best results. • LOI of samples treated with boron powder and silicon oil was not changed by leaching. - Abstract: In this study, effect of various concentrations of boron powder, mixture of boric acid and borax, fireproof agent based on liquid blend of limestone, and silicon oil on limited oxygen index levels (LOI) of S. pine wood was investigated. Wood samples were first vacuum treated with the preservatives, and then were subjected to leaching procedure. Samples treated with fireproof agent showed the best results for improving the fire retardancy of wood, furthermore, samples treated with 25%, 50% and 100% of the solution did not burn. Leaching did not considerably change the LOI of wood samples treated with boron powder and silicon oil; however, LOI levels of samples treated with the mixture of boric acid and borax and fireproof agent were affected by leaching procedure probably arising those preservatives did not chemically bond to main wood components. All treatments improved fire retardancy of samples despite some amount of preservatives leached out from wood.

Perinatal pathology: practice suggestions for limited-resource settings.

Science.gov (United States)

Roberts, Drucilla J

2013-06-01

The practice of perinatal pathology in much of the world suffers, as do all subspecialties of anatomic pathology, from inadequate resources (equipment, consumables, and both professional and technical personnel), from lack of education (not only of the pathologist but also of the clinicians responsible for sending the specimens, and the technicians processing the specimens), and from lack of appropriate government sector support. Perinatal pathology has significant public health-related utility and should be championing its service by providing maternal and fetal/infant mortality and morbidity data to governmental health ministries. It is with this pathologic data that informed decisions can be made on health-related courses of action and allocation of resources. These perinatal pathology data are needed to develop appropriate public health initiatives, specifically toward achieving the Millennium Developmental Goals as the best way to effectively decrease infant and maternal deaths and to determine causes of perinatal mortality and morbidity. The following overview will focus on the utility of perinatal pathology specifically as related to its public health function and will suggest methods to improve its service in resource-poor settings. This article is offered not as a critique of the current practice that most pathologists find themselves working in globally, but to provide suggestions for improving perinatal pathology services, which could be implemented with the limited available resources and manpower most pathology departments currently have. In addition, we offer suggestions for graded improvements ("ramping up") over time.

Perceived climate in physical activity settings.

Science.gov (United States)

Gill, Diane L; Morrow, Ronald G; Collins, Karen E; Lucey, Allison B; Schultz, Allison M

2010-01-01

This study focused on the perceived climate for LGBT youth and other minority groups in physical activity settings. A large sample of undergraduates and a selected sample including student teachers/interns and a campus Pride group completed a school climate survey and rated the climate in three physical activity settings (physical education, organized sport, exercise). Overall, school climate survey results paralleled the results with national samples revealing high levels of homophobic remarks and low levels of intervention. Physical activity climate ratings were mid-range, but multivariate analysis of variation test (MANOVA) revealed clear differences with all settings rated more inclusive for racial/ethnic minorities and most exclusive for gays/lesbians and people with disabilities. The results are in line with national surveys and research suggesting sexual orientation and physical characteristics are often the basis for harassment and exclusion in sport and physical activity. The current results also indicate that future physical activity professionals recognize exclusion, suggesting they could benefit from programs that move beyond awareness to skills and strategies for creating more inclusive programs.

Joint level-set and spatio-temporal motion detection for cell segmentation.

Science.gov (United States)

Boukari, Fatima; Makrogiannis, Sokratis

2016-08-10

Cell segmentation is a critical step for quantification and monitoring of cell cycle progression, cell migration, and growth control to investigate cellular immune response, embryonic development, tumorigenesis, and drug effects on live cells in time-lapse microscopy images. In this study, we propose a joint spatio-temporal diffusion and region-based level-set optimization approach for moving cell segmentation. Moving regions are initially detected in each set of three consecutive sequence images by numerically solving a system of coupled spatio-temporal partial differential equations. In order to standardize intensities of each frame, we apply a histogram transformation approach to match the pixel intensities of each processed frame with an intensity distribution model learned from all frames of the sequence during the training stage. After the spatio-temporal diffusion stage is completed, we compute the edge map by nonparametric density estimation using Parzen kernels. This process is followed by watershed-based segmentation and moving cell detection. We use this result as an initial level-set function to evolve the cell boundaries, refine the delineation, and optimize the final segmentation result. We applied this method to several datasets of fluorescence microscopy images with varying levels of difficulty with respect to cell density, resolution, contrast, and signal-to-noise ratio. We compared the results with those produced by Chan and Vese segmentation, a temporally linked level-set technique, and nonlinear diffusion-based segmentation. We validated all segmentation techniques against reference masks provided by the international Cell Tracking Challenge consortium. The proposed approach delineated cells with an average Dice similarity coefficient of 89 % over a variety of simulated and real fluorescent image sequences. It yielded average improvements of 11 % in segmentation accuracy compared to both strictly spatial and temporally linked Chan

Evaluation of recommendations on limits of exposure to ultraviolet radiation on the basis of data from the Austrian population

International Nuclear Information System (INIS)

Keck, G.; Schauberger, G.; Cabaj, A.

1996-01-01

For the application of solaria at present the following international recommendations on limits of exposure exist, which differ strongly: 1. IRPA/INIRC (1991): 30 MED/a (i.e. 7.5 kJ/a). 2. IEC 335-2-27 (1978, 1989): 25 kJ/m 2 /a for each region of the body, that is 100 MED/a. On the basis of our data from the Austrian population we give an evaluation of these recommendations for the entire population. This evaluation shows that 100 MED/a is much too high, it seduces rather to use solaria than to restrict their application

Evaluation of one-dimensional and two-dimensional volatility basis sets in simulating the aging of secondary organic aerosol with smog-chamber experiments.

Science.gov (United States)

Zhao, Bin; Wang, Shuxiao; Donahue, Neil M; Chuang, Wayne; Hildebrandt Ruiz, Lea; Ng, Nga L; Wang, Yangjun; Hao, Jiming

2015-02-17

We evaluate the one-dimensional volatility basis set (1D-VBS) and two-dimensional volatility basis set (2D-VBS) in simulating the aging of SOA derived from toluene and α-pinene against smog-chamber experiments. If we simulate the first-generation products with empirical chamber fits and the subsequent aging chemistry with a 1D-VBS or a 2D-VBS, the models mostly overestimate the SOA concentrations in the toluene oxidation experiments. This is because the empirical chamber fits include both first-generation oxidation and aging; simulating aging in addition to this results in double counting of the initial aging effects. If the first-generation oxidation is treated explicitly, the base-case 2D-VBS underestimates the SOA concentrations and O:C increase of the toluene oxidation experiments; it generally underestimates the SOA concentrations and overestimates the O:C increase of the α-pinene experiments. With the first-generation oxidation treated explicitly, we could modify the 2D-VBS configuration individually for toluene and α-pinene to achieve good model-measurement agreement. However, we are unable to simulate the oxidation of both toluene and α-pinene with the same 2D-VBS configuration. We suggest that future models should implement parallel layers for anthropogenic (aromatic) and biogenic precursors, and that more modeling studies and laboratory research be done to optimize the "best-guess" parameters for each layer.

A new level set model for cell image segmentation

Science.gov (United States)

Ma, Jing-Feng; Hou, Kai; Bao, Shang-Lian; Chen, Chun

2011-02-01

In this paper we first determine three phases of cell images: background, cytoplasm and nucleolus according to the general physical characteristics of cell images, and then develop a variational model, based on these characteristics, to segment nucleolus and cytoplasm from their relatively complicated backgrounds. In the meantime, the preprocessing obtained information of cell images using the OTSU algorithm is used to initialize the level set function in the model, which can speed up the segmentation and present satisfactory results in cell image processing.

TECHNICAL BASIS FOR VENTILATION REQUIREMENTS IN TANK FARMS OPERATING SPECIFICATIONS DOCUMENTS

Energy Technology Data Exchange (ETDEWEB)

BERGLIN, E J

2003-06-23

This report provides the technical basis for high efficiency particulate air filter (HEPA) for Hanford tank farm ventilation systems (sometimes known as heating, ventilation and air conditioning [HVAC]) to support limits defined in Process Engineering Operating Specification Documents (OSDs). This technical basis included a review of older technical basis and provides clarifications, as necessary, to technical basis limit revisions or justification. This document provides an updated technical basis for tank farm ventilation systems related to Operation Specification Documents (OSDs) for double-shell tanks (DSTs), single-shell tanks (SSTs), double-contained receiver tanks (DCRTs), catch tanks, and various other miscellaneous facilities.

Experiments in Reconstructing Twentieth-Century Sea Levels

Science.gov (United States)

Ray, Richard D.; Douglas, Bruce C.

2011-01-01

One approach to reconstructing historical sea level from the relatively sparse tide-gauge network is to employ Empirical Orthogonal Functions (EOFs) as interpolatory spatial basis functions. The EOFs are determined from independent global data, generally sea-surface heights from either satellite altimetry or a numerical ocean model. The problem is revisited here for sea level since 1900. A new approach to handling the tide-gauge datum problem by direct solution offers possible advantages over the method of integrating sea-level differences, with the potential of eventually adjusting datums into the global terrestrial reference frame. The resulting time series of global mean sea levels appears fairly insensitive to the adopted set of EOFs. In contrast, charts of regional sea level anomalies and trends are very sensitive to the adopted set of EOFs, especially for the sparser network of gauges in the early 20th century. The reconstructions appear especially suspect before 1950 in the tropical Pacific. While this limits some applications of the sea-level reconstructions, the sensitivity does appear adequately captured by formal uncertainties. All our solutions show regional trends over the past five decades to be fairly uniform throughout the global ocean, in contrast to trends observed over the shorter altimeter era. Consistent with several previous estimates, the global sea-level rise since 1900 is 1.70 +/- 0.26 mm/yr. The global trend since 1995 exceeds 3 mm/yr which is consistent with altimeter measurements, but this large trend was possibly also reached between 1935 and 1950.

Teamwork skills in actual, in situ, and in-center pediatric emergencies: performance levels across settings and perceptions of comparative educational impact.

Science.gov (United States)

Couto, Thomaz Bittencourt; Kerrey, Benjamin T; Taylor, Regina G; FitzGerald, Michael; Geis, Gary L

2015-04-01

Pediatric emergencies require effective teamwork. These skills are developed and demonstrated in actual emergencies and in simulated environments, including simulation centers (in center) and the real care environment (in situ). Our aims were to compare teamwork performance across these settings and to identify perceived educational strengths and weaknesses between simulated settings. We hypothesized that teamwork performance in actual emergencies and in situ simulations would be higher than for in-center simulations. A retrospective, video-based assessment of teamwork was performed in an academic, pediatric level 1 trauma center, using the Team Emergency Assessment Measure (TEAM) tool (range, 0-44) among emergency department providers (physicians, nurses, respiratory therapists, paramedics, patient care assistants, and pharmacists). A survey-based, cross-sectional assessment was conducted to determine provider perceptions regarding simulation training. One hundred thirty-two videos, 44 from each setting, were reviewed. Mean total TEAM scores were similar and high in all settings (31.2 actual, 31.1 in situ, and 32.3 in-center, P = 0.39). Of 236 providers, 154 (65%) responded to the survey. For teamwork training, in situ simulation was considered more realistic (59% vs. 10%) and more effective (45% vs. 15%) than in-center simulation. In a video-based study in an academic pediatric institution, ratings of teamwork were relatively high among actual resuscitations and 2 simulation settings, substantiating the influence of simulation-based training on instilling a culture of communication and teamwork. On the basis of survey results, providers favored the in situ setting for teamwork training and suggested an expansion of our existing in situ program.

Relay protection coordination with generator capability curve, excitation system limiters and power system relay protections settings

Directory of Open Access Journals (Sweden)

Buha Danilo

2016-01-01

Full Text Available The relay protection settings performed in the largest thermal powerplant (TE "Nikola Tesla B" are reffered and explained in this paper. The first calculation step is related to the coordination of the maximum stator current limiter settings, the overcurrent protection with inverse characteristics settings and the permitted overload of the generator stator B1. In the second calculation step the settings of impedance generator protection are determined, and the methods and criteria according to which the calculations are done are described. Criteria used to provide the protection to fulfill the backup protection role in the event of malfunction of the main protection of the transmission system. are clarified. The calculation of all protection functions (32 functions of generator B1 were performed in the project "Coordination of relay protection blocks B1 and B2 with the system of excitation and power system protections -TENT B".

Mobile learning for HIV/AIDS healthcare worker training in resource-limited settings

Directory of Open Access Journals (Sweden)

Zolfo Maria

2010-09-01

Full Text Available Abstract Background We present an innovative approach to healthcare worker (HCW training using mobile phones as a personal learning environment. Twenty physicians used individual Smartphones (Nokia N95 and iPhone, each equipped with a portable solar charger. Doctors worked in urban and peri-urban HIV/AIDS clinics in Peru, where almost 70% of the nation's HIV patients in need are on treatment. A set of 3D learning scenarios simulating interactive clinical cases was developed and adapted to the Smartphones for a continuing medical education program lasting 3 months. A mobile educational platform supporting learning events tracked participant learning progress. A discussion forum accessible via mobile connected participants to a group of HIV specialists available for back-up of the medical information. Learning outcomes were verified through mobile quizzes using multiple choice questions at the end of each module. Methods In December 2009, a mid-term evaluation was conducted, targeting both technical feasibility and user satisfaction. It also highlighted user perception of the program and the technical challenges encountered using mobile devices for lifelong learning. Results With a response rate of 90% (18/20 questionnaires returned, the overall satisfaction of using mobile tools was generally greater for the iPhone. Access to Skype and Facebook, screen/keyboard size, and image quality were cited as more troublesome for the Nokia N95 compared to the iPhone. Conclusions Training, supervision and clinical mentoring of health workers are the cornerstone of the scaling up process of HIV/AIDS care in resource-limited settings (RLSs. Educational modules on mobile phones can give flexibility to HCWs for accessing learning content anywhere. However lack of softwares interoperability and the high investment cost for the Smartphones' purchase could represent a limitation to the wide spread use of such kind mLearning programs in RLSs.

Relationship between Perceived Limit-Setting Abilities, Autism Spectrum Disorder Severity, Behaviour Problems and Parenting Stress in Mothers of Children with Autism Spectrum Disorder

Science.gov (United States)

Reed, Phil; Howse, Jessie; Ho, Ben; Osborne, Lisa A.

2017-01-01

Parenting stress in mothers of children with autism spectrum disorder (ASD) is high and impacts perceptions about parenting. This study examined the relationship between parenting stress and observer-perceived limit-setting ability. Participants' perceptions of other parents' limit-setting ability were assessed by showing participants video clips…

Level-set-based reconstruction algorithm for EIT lung images: first clinical results.

Science.gov (United States)

Rahmati, Peyman; Soleimani, Manuchehr; Pulletz, Sven; Frerichs, Inéz; Adler, Andy

2012-05-01

We show the first clinical results using the level-set-based reconstruction algorithm for electrical impedance tomography (EIT) data. The level-set-based reconstruction method (LSRM) allows the reconstruction of non-smooth interfaces between image regions, which are typically smoothed by traditional voxel-based reconstruction methods (VBRMs). We develop a time difference formulation of the LSRM for 2D images. The proposed reconstruction method is applied to reconstruct clinical EIT data of a slow flow inflation pressure-volume manoeuvre in lung-healthy and adult lung-injury patients. Images from the LSRM and the VBRM are compared. The results show comparable reconstructed images, but with an improved ability to reconstruct sharp conductivity changes in the distribution of lung ventilation using the LSRM.

Level-set-based reconstruction algorithm for EIT lung images: first clinical results

International Nuclear Information System (INIS)

Rahmati, Peyman; Adler, Andy; Soleimani, Manuchehr; Pulletz, Sven; Frerichs, Inéz

2012-01-01

We show the first clinical results using the level-set-based reconstruction algorithm for electrical impedance tomography (EIT) data. The level-set-based reconstruction method (LSRM) allows the reconstruction of non-smooth interfaces between image regions, which are typically smoothed by traditional voxel-based reconstruction methods (VBRMs). We develop a time difference formulation of the LSRM for 2D images. The proposed reconstruction method is applied to reconstruct clinical EIT data of a slow flow inflation pressure–volume manoeuvre in lung-healthy and adult lung-injury patients. Images from the LSRM and the VBRM are compared. The results show comparable reconstructed images, but with an improved ability to reconstruct sharp conductivity changes in the distribution of lung ventilation using the LSRM. (paper)

Principles for the limitation of releases of radionuclides from nuclear power plants to the atmosphere. A model of food chain system

International Nuclear Information System (INIS)

Pensko, J.; Stpiczynska, Z.

1976-01-01

On the basis of reference data the principles are set up for the limitation of releases of radioactive substances from nuclear power plants to the environment to maintain the radiation exposure of population to the level of accepted dose limits. The main attention is paid to the transfer of radionuclides released through food chain to man. For that purpose the mathematical model of population exposure by food chain which relates the radiation doses to the activity of radionuclides released is presented. The Laplace transformation is used to simplify the solution of the differential equations. It is shown that the estimation of the population exposure with the aid of a food chain mathematical model not only gives the permissible limits of release but also indicates the ways of proper radiological control program in the environment of nuclear installations. (author)

Why there is a need to revise the design basis threat concept

International Nuclear Information System (INIS)

Kondratov, S.; Steinhaeusler, F.

2005-01-01

Full text: The coordinated terrorist attacks in the United States on September 11, 2001, necessitated the review of the proven concept of the Design Basis Threat (DBT) for nuclear installations. It is safe to assume that revised and upgraded DBT will result in costly technical solutions. Since infrastructure deficits and financial limitations in many countries have already limited the practical application of the DBT in many instances, the revised threat assessment is likely to worsen the current dissatisfactory situation further. Therefore, a new realism in the use of the DBT concept is proposed, based on a three-level approach. This will enable countries to tailor the design of their physical protection systems in accordance with their means by implementing either a minimum required security level protecting only against the most probable threat, or aiming for an intermediate protection level reflecting the newly introduced AHARA - as high as reasonably achievable - principle, or providing the optimum protection level based on an externally reviewed, fully comprehensive DBT. (author)

Why there is a need to revise the Design Basis Threat concept

International Nuclear Information System (INIS)

Kondratov, S.; Steinhausler, F.

2006-01-01

The terrorist attacks in the USA on 11 September 2001 necessitated a review of the proven concept of the Design Basis Threat (DBT) for nuclear installations. It can be assumed that revised and upgraded DBT will result in costly technical solutions. Since infrastructure deficits and financial limitations in many countries have already limited the practical application of the DBT, the revised threat assessment is likely to worsen the current unsatisfactory situation. Therefore, a new realism in the use of the DBT concept is proposed based on a three-level approach. This will enable countries to tailor the design of their physical protection systems in accordance with their means by implementing either a minimum required security level protecting only against the most probable threat, or an intermediate protection level reflecting the newly introduced AHARA (As High As Reasonably Achievable) principle, or the optimum protection level based on an externally reviewed, fully comprehensive DBT. (author)

Many-Body Energy Decomposition with Basis Set Superposition Error Corrections.

Science.gov (United States)

Mayer, István; Bakó, Imre

2017-05-09

The problem of performing many-body decompositions of energy is considered in the case when BSSE corrections are also performed. It is discussed that the two different schemes that have been proposed go back to the two different interpretations of the original Boys-Bernardi counterpoise correction scheme. It is argued that from the physical point of view the "hierarchical" scheme of Valiron and Mayer should be preferred and not the scheme recently discussed by Ouyang and Bettens, because it permits the energy of the individual monomers and all the two-body, three-body, etc. energy components to be free of unphysical dependence on the arrangement (basis functions) of other subsystems in the cluster.

Level set segmentation of bovine corpora lutea in ex situ ovarian ultrasound images

Directory of Open Access Journals (Sweden)

Adams Gregg P

2008-08-01

Full Text Available Abstract Background The objective of this study was to investigate the viability of level set image segmentation methods for the detection of corpora lutea (corpus luteum, CL boundaries in ultrasonographic ovarian images. It was hypothesized that bovine CL boundaries could be located within 1–2 mm by a level set image segmentation methodology. Methods Level set methods embed a 2D contour in a 3D surface and evolve that surface over time according to an image-dependent speed function. A speed function suitable for segmentation of CL's in ovarian ultrasound images was developed. An initial contour was manually placed and contour evolution was allowed to proceed until the rate of change of the area was sufficiently small. The method was tested on ovarian ultrasonographic images (n = 8 obtained ex situ. A expert in ovarian ultrasound interpretation delineated CL boundaries manually to serve as a "ground truth". Accuracy of the level set segmentation algorithm was determined by comparing semi-automatically determined contours with ground truth contours using the mean absolute difference (MAD, root mean squared difference (RMSD, Hausdorff distance (HD, sensitivity, and specificity metrics. Results and discussion The mean MAD was 0.87 mm (sigma = 0.36 mm, RMSD was 1.1 mm (sigma = 0.47 mm, and HD was 3.4 mm (sigma = 2.0 mm indicating that, on average, boundaries were accurate within 1–2 mm, however, deviations in excess of 3 mm from the ground truth were observed indicating under- or over-expansion of the contour. Mean sensitivity and specificity were 0.814 (sigma = 0.171 and 0.990 (sigma = 0.00786, respectively, indicating that CLs were consistently undersegmented but rarely did the contour interior include pixels that were judged by the human expert not to be part of the CL. It was observed that in localities where gradient magnitudes within the CL were strong due to high contrast speckle, contour expansion stopped too early. Conclusion The

Level Set Projection Method for Incompressible Navier-Stokes on Arbitrary Boundaries

KAUST Repository

Williams-Rioux, Bertrand

2012-01-12

Second order level set projection method for incompressible Navier-Stokes equations is proposed to solve flow around arbitrary geometries. We used rectilinear grid with collocated cell centered velocity and pressure. An explicit Godunov procedure is used to address the nonlinear advection terms, and an implicit Crank-Nicholson method to update viscous effects. An approximate pressure projection is implemented at the end of the time stepping using multigrid as a conventional fast iterative method. The level set method developed by Osher and Sethian [17] is implemented to address real momentum and pressure boundary conditions by the advection of a distance function, as proposed by Aslam [3]. Numerical results for the Strouhal number and drag coefficients validated the model with good accuracy for flow over a cylinder in the parallel shedding regime (47 < Re < 180). Simulations for an array of cylinders and an oscillating cylinder were performed, with the latter demonstrating our methods ability to handle dynamic boundary conditions.

Amino acid limitation induces down-regulation of WNT5a at transcriptional level

International Nuclear Information System (INIS)

Wang Zuguang; Chen Hong

2009-01-01

An aberrant WNT signaling contributes to the development and progression of multiple cancers. WNT5a is one of the WNT signaling molecules. This study was designed to test the hypothesis that amino acid deprivation induces changes in the WNT signaling pathway in colon cancer cells. Results showed that targets of the amino acid response pathway, ATF3 and p21, were induced in the human colon cancer cell line SW480 during amino acid limitation. There was a significant decrease in the WNT5a mRNA level following amino acid deprivation. The down-regulation of WNT5a mRNA by amino acid deprivation is not due to mRNA destabilization. There is a reduction of nuclear β-catenin protein level by amino acid limitation. Under amino acid limitation, phosphorylation of ERK1/2 was increased and the blockage of ERK1/2 by the inhibitor U0126 partially restored WNT5a mRNA level. In conclusion, amino acid limitation in colon cancer cells induces phosphorylation of ERK1/2, which then down-regulates WNT5a expression.

Benchmark calculations with correlated molecular wave functions. VII. Binding energy and structure of the HF dimer

International Nuclear Information System (INIS)

Peterson, K.A.; Dunning, T.H. Jr.

1995-01-01

The hydrogen bond energy and geometry of the HF dimer have been investigated using the series of correlation consistent basis sets from aug-cc-pVDZ to aug-cc-pVQZ and several theoretical methods including Moller--Plesset perturbation and coupled cluster theories. Estimates of the complete basis set (CBS) limit have been derived for the binding energy of (HF) 2 at each level of theory by utilizing the regular convergence characteristics of the correlation consistent basis sets. CBS limit hydrogen bond energies of 3.72, 4.53, 4.55, and 4.60 kcal/mol are estimated at the SCF, MP2, MP4, and CCSD(T) levels of theory, respectively. CBS limits for the intermolecular F--F distance are estimated to be 2.82, 2.74, 2.73, and 2.73 A, respectively, for the same correlation methods. The effects of basis set superposition error (BSSE) on both the binding energies and structures have also been investigated for each basis set using the standard function counterpoise (CP) method. While BSSE has a negligible effect on the intramolecular geometries, the CP-corrected F--F distance and binding energy differ significantly from the uncorrected values for the aug-cc-pVDZ basis set; these differences decrease regularly with increasing basis set size, yielding the same limits in the CBS limit. Best estimates for the equilibrium properties of the HF dimer from CCSD(T) calculations are D e =4.60 kcal/mol, R FF =2.73 A, r 1 =0.922 A, r 2 =0.920 A, Θ 1 =7 degree, and Θ 2 =111 degree

Stochastic level-set variational implicit-solvent approach to solute-solvent interfacial fluctuations

Energy Technology Data Exchange (ETDEWEB)

Zhou, Shenggao, E-mail: sgzhou@suda.edu.cn, E-mail: bli@math.ucsd.edu [Department of Mathematics and Mathematical Center for Interdiscipline Research, Soochow University, 1 Shizi Street, Jiangsu, Suzhou 215006 (China); Sun, Hui; Cheng, Li-Tien [Department of Mathematics, University of California, San Diego, La Jolla, California 92093-0112 (United States); Dzubiella, Joachim [Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany and Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin (Germany); Li, Bo, E-mail: sgzhou@suda.edu.cn, E-mail: bli@math.ucsd.edu [Department of Mathematics and Quantitative Biology Graduate Program, University of California, San Diego, La Jolla, California 92093-0112 (United States); McCammon, J. Andrew [Department of Chemistry and Biochemistry, Department of Pharmacology, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, California 92093-0365 (United States)

2016-08-07

Recent years have seen the initial success of a variational implicit-solvent model (VISM), implemented with a robust level-set method, in capturing efficiently different hydration states and providing quantitatively good estimation of solvation free energies of biomolecules. The level-set minimization of the VISM solvation free-energy functional of all possible solute-solvent interfaces or dielectric boundaries predicts an equilibrium biomolecular conformation that is often close to an initial guess. In this work, we develop a theory in the form of Langevin geometrical flow to incorporate solute-solvent interfacial fluctuations into the VISM. Such fluctuations are crucial to biomolecular conformational changes and binding process. We also develop a stochastic level-set method to numerically implement such a theory. We describe the interfacial fluctuation through the “normal velocity” that is the solute-solvent interfacial force, derive the corresponding stochastic level-set equation in the sense of Stratonovich so that the surface representation is independent of the choice of implicit function, and develop numerical techniques for solving such an equation and processing the numerical data. We apply our computational method to study the dewetting transition in the system of two hydrophobic plates and a hydrophobic cavity of a synthetic host molecule cucurbit[7]uril. Numerical simulations demonstrate that our approach can describe an underlying system jumping out of a local minimum of the free-energy functional and can capture dewetting transitions of hydrophobic systems. In the case of two hydrophobic plates, we find that the wavelength of interfacial fluctuations has a strong influence to the dewetting transition. In addition, we find that the estimated energy barrier of the dewetting transition scales quadratically with the inter-plate distance, agreeing well with existing studies of molecular dynamics simulations. Our work is a first step toward the