Sokalski, W. A.; Shibata, M.; Ornstein, R. L.; Rein, R.
1992-01-01
The quality of several atomic charge models based on different definitions has been analyzed using cumulative atomic multipole moments (CAMM). This formalism can generate higher atomic moments starting from any atomic charges, while preserving the corresponding molecular moments. The atomic charge contribution to the higher molecular moments, as well as to the electrostatic potentials, has been examined for CO and HCN molecules at several different levels of theory. The results clearly show that the electrostatic potential obtained from CAMM expansion is convergent up to R-5 term for all atomic charge models used. This illustrates that higher atomic moments can be used to supplement any atomic charge model to obtain more accurate description of electrostatic properties.
HPAM: Hirshfeld partitioned atomic multipoles
Elking, Dennis M.; Perera, Lalith; Pedersen, Lee G.
2012-02-01
An implementation of the Hirshfeld (HD) and Hirshfeld-Iterated (HD-I) atomic charge density partitioning schemes is described. Atomic charges and atomic multipoles are calculated from the HD and HD-I atomic charge densities for arbitrary atomic multipole rank l on molecules of arbitrary shape and size. The HD and HD-I atomic charges/multipoles are tested by comparing molecular multipole moments and the electrostatic potential (ESP) surrounding a molecule with their reference ab initio values. In general, the HD-I atomic charges/multipoles are found to better reproduce ab initio electrostatic properties over HD atomic charges/multipoles. A systematic increase in precision for reproducing ab initio electrostatic properties is demonstrated by increasing the atomic multipole rank from l=0 (atomic charges) to l=4 (atomic hexadecapoles). Both HD and HD-I atomic multipoles up to rank l are shown to exactly reproduce ab initio molecular multipole moments of rank L for L⩽l. In addition, molecular dipole moments calculated by HD, HD-I, and ChelpG atomic charges only ( l=0) are compared with reference ab initio values. Significant errors in reproducing ab initio molecular dipole moments are found if only HD or HD-I atomic charges used. Program summaryProgram title: HPAM Catalogue identifier: AEKP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKP_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License v2 No. of lines in distributed program, including test data, etc.: 500 809 No. of bytes in distributed program, including test data, etc.: 13 424 494 Distribution format: tar.gz Programming language: C Computer: Any Operating system: Linux RAM: Typically, a few hundred megabytes Classification: 16.13 External routines: The program requires 'formatted checkpoint' files obtained from the Gaussian 03 or Gaussian 09 quantum chemistry program. Nature of problem: An ab initio
Multipole correction of atomic monopole models of molecular charge distribution. I. Peptides
Sokalski, W. A.; Keller, D. A.; Ornstein, R. L.; Rein, R.
1993-01-01
The defects in atomic monopole models of molecular charge distribution have been analyzed for several model-blocked peptides and compared with accurate quantum chemical values. The results indicate that the angular characteristics of the molecular electrostatic potential around functional groups capable of forming hydrogen bonds can be considerably distorted within various models relying upon isotropic atomic charges only. It is shown that these defects can be corrected by augmenting the atomic point charge models by cumulative atomic multipole moments (CAMMs). Alternatively, sets of off-center atomic point charges could be automatically derived from respective multipoles, providing approximately equivalent corrections. For the first time, correlated atomic multipoles have been calculated for N-acetyl, N'-methylamide-blocked derivatives of glycine, alanine, cysteine, threonine, leucine, lysine, and serine using the MP2 method. The role of the correlation effects in the peptide molecular charge distribution are discussed.
Prediction of conformationally dependent atomic multipole moments in carbohydrates.
Cardamone, Salvatore; Popelier, Paul L A
2015-12-15
The conformational flexibility of carbohydrates is challenging within the field of computational chemistry. This flexibility causes the electron density to change, which leads to fluctuating atomic multipole moments. Quantum Chemical Topology (QCT) allows for the partitioning of an "atom in a molecule," thus localizing electron density to finite atomic domains, which permits the unambiguous evaluation of atomic multipole moments. By selecting an ensemble of physically realistic conformers of a chemical system, one evaluates the various multipole moments at defined points in configuration space. The subsequent implementation of the machine learning method kriging delivers the evaluation of an analytical function, which smoothly interpolates between these points. This allows for the prediction of atomic multipole moments at new points in conformational space, not trained for but within prediction range. In this work, we demonstrate that the carbohydrates erythrose and threose are amenable to the above methodology. We investigate how kriging models respond when the training ensemble incorporating multiple energy minima and their environment in conformational space. Additionally, we evaluate the gains in predictive capacity of our models as the size of the training ensemble increases. We believe this approach to be entirely novel within the field of carbohydrates. For a modest training set size of 600, more than 90% of the external test configurations have an error in the total (predicted) electrostatic energy (relative to ab initio) of maximum 1 kJ mol(-1) for open chains and just over 90% an error of maximum 4 kJ mol(-1) for rings. © 2015 Wiley Periodicals, Inc.
Deriving static atomic multipoles from the electrostatic potential.
Kramer, Christian; Bereau, Tristan; Spinn, Alexander; Liedl, Klaus R; Gedeck, Peter; Meuwly, Markus
2013-12-23
The description of molecular systems using multipolar electrostatics calls for automated methods to fit the necessary parameters. In this paper, we describe an open-source software package that allows fitting atomic multipoles (MTPs) from the ab initio electrostatic potential by adequate atom typing and judicious assignment of the local axis system. By enabling the simultaneous fit of several molecules and/or conformations, the package addresses issues of parameter transferability and lack of sampling for buried atoms. We illustrate the method by studying a series of small alcohol molecules, as well as various conformations of protonated butylamine.
Polarizable Atomic Multipole Solutes in a Poisson-Boltzmann Continuum
Schnieders, Michael J.; Baker, Nathan A.; Ren, Pengyu; Ponder, Jay W.
2008-01-01
Modeling the change in the electrostatics of organic molecules upon moving from vacuum into solvent, due to polarization, has long been an interesting problem. In vacuum, experimental values for the dipole moments and polarizabilities of small, rigid molecules are known to high accuracy; however, it has generally been difficult to determine these quantities for a polar molecule in water. A theoretical approach introduced by Onsager used vacuum properties of small molecules, including polarizability, dipole moment and size, to predict experimentally known permittivities of neat liquids via the Poisson equation. Since this important advance in understanding the condensed phase, a large number of computational methods have been developed to study solutes embedded in a continuum via numerical solutions to the Poisson-Boltzmann equation (PBE). Only recently have the classical force fields used for studying biomolecules begun to include explicit polarization in their functional forms. Here we describe the theory underlying a newly developed Polarizable Multipole Poisson-Boltzmann (PMPB) continuum electrostatics model, which builds on the Atomic Multipole Optimized Energetics for Biomolecular Applications (AMOEBA) force field. As an application of the PMPB methodology, results are presented for several small folded proteins studied by molecular dynamics in explicit water as well as embedded in the PMPB continuum. The dipole moment of each protein increased on average by a factor of 1.27 in explicit water and 1.26 in continuum solvent. The essentially identical electrostatic response in both models suggests that PMPB electrostatics offers an efficient alternative to sampling explicit solvent molecules for a variety of interesting applications, including binding energies, conformational analysis, and pKa prediction. Introduction of 150 mM salt lowered the electrostatic solvation energy between 2–13 kcal/mole, depending on the formal charge of the protein, but had only a
Revised Parameters for the AMOEBA Polarizable Atomic Multipole Water Model.
Laury, Marie L; Wang, Lee-Ping; Pande, Vijay S; Head-Gordon, Teresa; Ponder, Jay W
2015-07-23
A set of improved parameters for the AMOEBA polarizable atomic multipole water model is developed. An automated procedure, ForceBalance, is used to adjust model parameters to enforce agreement with ab initio-derived results for water clusters and experimental data for a variety of liquid phase properties across a broad temperature range. The values reported here for the new AMOEBA14 water model represent a substantial improvement over the previous AMOEBA03 model. The AMOEBA14 model accurately predicts the temperature of maximum density and qualitatively matches the experimental density curve across temperatures from 249 to 373 K. Excellent agreement is observed for the AMOEBA14 model in comparison to experimental properties as a function of temperature, including the second virial coefficient, enthalpy of vaporization, isothermal compressibility, thermal expansion coefficient, and dielectric constant. The viscosity, self-diffusion constant, and surface tension are also well reproduced. In comparison to high-level ab initio results for clusters of 2-20 water molecules, the AMOEBA14 model yields results similar to AMOEBA03 and the direct polarization iAMOEBA models. With advances in computing power, calibration data, and optimization techniques, we recommend the use of the AMOEBA14 water model for future studies employing a polarizable water model.
Polarizable atomic multipole X-ray refinement: application to peptide crystals
Energy Technology Data Exchange (ETDEWEB)
Schnieders, Michael J. [Department of Chemistry, Stanford, CA 94305 (United States); Fenn, Timothy D. [Department of Molecular and Cellular Physiology, Stanford, CA 94305 (United States); Howard Hughes Medical Institute (United States); Pande, Vijay S., E-mail: pande@stanford.edu [Department of Chemistry, Stanford, CA 94305 (United States); Brunger, Axel T., E-mail: pande@stanford.edu [Department of Molecular and Cellular Physiology, Stanford, CA 94305 (United States); Howard Hughes Medical Institute (United States); Department of Chemistry, Stanford, CA 94305 (United States)
2009-09-01
A method to accelerate the computation of structure factors from an electron density described by anisotropic and aspherical atomic form factors via fast Fourier transformation is described for the first time. Recent advances in computational chemistry have produced force fields based on a polarizable atomic multipole description of biomolecular electrostatics. In this work, the Atomic Multipole Optimized Energetics for Biomolecular Applications (AMOEBA) force field is applied to restrained refinement of molecular models against X-ray diffraction data from peptide crystals. A new formalism is also developed to compute anisotropic and aspherical structure factors using fast Fourier transformation (FFT) of Cartesian Gaussian multipoles. Relative to direct summation, the FFT approach can give a speedup of more than an order of magnitude for aspherical refinement of ultrahigh-resolution data sets. Use of a sublattice formalism makes the method highly parallelizable. Application of the Cartesian Gaussian multipole scattering model to a series of four peptide crystals using multipole coefficients from the AMOEBA force field demonstrates that AMOEBA systematically underestimates electron density at bond centers. For the trigonal and tetrahedral bonding geometries common in organic chemistry, an atomic multipole expansion through hexadecapole order is required to explain bond electron density. Alternatively, the addition of interatomic scattering (IAS) sites to the AMOEBA-based density captured bonding effects with fewer parameters. For a series of four peptide crystals, the AMOEBA–IAS model lowered R{sub free} by 20–40% relative to the original spherically symmetric scattering model.
Jakobsen, Sofie; Jensen, Frank
2014-12-09
We assess the accuracy of force field (FF) electrostatics at several levels of approximation from the standard model using fixed partial charges to conformational specific multipole fits including up to quadrupole moments. Potential-derived point charges and multipoles are calculated using least-squares methods for a total of ∼1000 different conformations of the 20 natural amino acids. Opposed to standard charge fitting schemes the procedure presented in the current work employs fitting points placed on a single isodensity surface, since the electrostatic potential (ESP) on such a surface determines the ESP at all points outside this surface. We find that the effect of multipoles beyond partial atomic charges is of the same magnitude as the effect due to neglecting conformational dependency (i.e., polarizability), suggesting that the two effects should be included at the same level in FF development. The redundancy at both the partial charge and multipole levels of approximation is quantified. We present an algorithm which stepwise reduces or increases the dimensionality of the charge or multipole parameter space and provides an upper limit of the ESP error that can be obtained at a given truncation level. Thereby, we can identify a reduced set of multipole moments corresponding to ∼40% of the total number of multipoles. This subset of parameters provides a significant improvement in the representation of the ESP compared to the simple point charge model and close to the accuracy obtained using the complete multipole parameter space. The selection of the ∼40% most important multipole sites is highly transferable among different conformations, and we find that quadrupoles are of high importance for atoms involved in π-bonding, since the anisotropic electric field generated in such regions requires a large degree of flexibility.
Elking, Dennis M
2016-08-15
New equations for torque and atomic force are derived for use in flexible molecule force fields with atomic multipoles. The expressions are based on Cartesian tensors with arbitrary multipole rank. The standard method for rotating Cartesian tensor multipoles and calculating torque is to first represent the tensor with n indexes and 3(n) redundant components. In this work, new expressions for directly rotating the unique (n + 1)(n + 2)/2 Cartesian tensor multipole components Θpqr are given by introducing Cartesian tensor rotation matrix elements X(R). A polynomial expression and a recursion relation for X(R) are derived. For comparison, the analogous rotation matrix for spherical tensor multipoles are the Wigner functions D(R). The expressions for X(R) are used to derive simple equations for torque and atomic force. The torque and atomic force equations are applied to the geometry optimization of small molecule crystal unit cells. In addition, a discussion of computational efficiency as a function of increasing multipole rank is given for Cartesian tensors. © 2016 Wiley Periodicals, Inc.
The Polarizable Atomic Multipole-based AMOEBA Force Field for Proteins.
Shi, Yue; Xia, Zhen; Zhang, Jiajing; Best, Robert; Wu, Chuanjie; Ponder, Jay W; Ren, Pengyu
2013-01-01
Development of the AMOEBA (Atomic Multipole Optimized Energetics for Biomolecular Simulation) force field for proteins is presented. The current version (AMOEBA-2013) utilizes permanent electrostatic multipole moments through the quadrupole at each atom, and explicitly treats polarization effects in various chemical and physical environments. The atomic multipole electrostatic parameters for each amino acid residue type are derived from high-level gas phase quantum mechanical calculations via a consistent and extensible protocol. Molecular polarizability is modeled via a Thole-style damped interactive induction model based upon distributed atomic polarizabilities. Inter- and intramolecular polarization is treated in a consistent fashion via the Thole model. The intramolecular polarization model ensures transferability of electrostatic parameters among different conformations, as demonstrated by the agreement between QM and AMOEBA electrostatic potentials, and dipole moments of dipeptides. The backbone and side chain torsional parameters were determined by comparing to gas-phase QM (RI-TRIM MP2/CBS) conformational energies of dipeptides and to statistical distributions from the Protein Data Bank. Molecular dynamics simulations are reported for short peptides in explicit water to examine their conformational properties in solution. Overall the calculated conformational free energies and J-coupling constants are consistent with PDB statistics and experimental NMR results, respectively. In addition, the experimental crystal structures of a number of proteins are well maintained during molecular dynamics (MD) simulation. While further calculations are necessary to fully validate the force field, initial results suggest the AMOEBA polarizable multipole force field is able to describe the structure and energetics of peptides and proteins, in both gas-phase and solution environments.
Szmytkowski, Radosław; Łukasik, Grzegorz
2016-09-01
We present tabulated data for several families of static electric and magnetic multipole susceptibilities for hydrogenic atoms with nuclear charge numbers from the range 1 ⩽ Z ⩽ 137. Atomic nuclei are assumed to be point-like and spinless. The susceptibilities considered include the multipole electric polarizabilities α E L → E L and magnetizabilities (magnetic susceptibilities) χ M L → M L with 1 ⩽ L ⩽ 4 (i.e., the dipole, quadrupole, octupole and hexadecapole ones), the electric-to-magnetic cross-susceptibilities α E L → M(L - 1) with 2 ⩽ L ⩽ 5 and α E L → M(L + 1) with 1 ⩽ L ⩽ 4, the magnetic-to-electric cross-susceptibilities χ M L → E(L - 1) with 2 ⩽ L ⩽ 5 and χ M L → E(L + 1) with 1 ⩽ L ⩽ 4 (it holds that χ M L → E(L ∓ 1) =α E(L ∓ 1) → M L), and the electric-to-toroidal-magnetic cross-susceptibilities α E L → T L with 1 ⩽ L ⩽ 4. Numerical values are computed from general exact analytical formulas, derived by us elsewhere within the framework of the Dirac relativistic quantum mechanics, and involving generalized hypergeometric functions 3F2 of the unit argument.
Pyzer-Knapp, Edward O.; Thompson, Hugh P. G.; Day, Graeme M.
2016-01-01
We present a re-parameterization of a popular intermolecular force field for describing intermolecular interactions in the organic solid state. Specifically we optimize the performance of the exp-6 force field when used in conjunction with atomic multipole electrostatics. We also parameterize force fields that are optimized for use with multipoles derived from polarized molecular electron densities, to account for induction effects in molecular crystals. Parameterization is performed against a set of 186 experimentally determined, low-temperature crystal structures and 53 measured sublimation enthalpies of hydrogen-bonding organic molecules. The resulting force fields are tested on a validation set of 129 crystal structures and show improved reproduction of the structures and lattice energies of a range of organic molecular crystals compared with the original force field with atomic partial charge electrostatics. Unit-cell dimensions of the validation set are typically reproduced to within 3% with the re-parameterized force fields. Lattice energies, which were all included during parameterization, are systematically underestimated when compared with measured sublimation enthalpies, with mean absolute errors of between 7.4 and 9.0%. PMID:27484370
Woo Kim, Hyun; Rhee, Young Min
2012-07-30
Recently, many polarizable force fields have been devised to describe induction effects between molecules. In popular polarizable models based on induced dipole moments, atomic polarizabilities are the essential parameters and should be derived carefully. Here, we present a parameterization scheme for atomic polarizabilities using a minimization target function containing both molecular and atomic information. The main idea is to adopt reference data only from quantum chemical calculations, to perform atomic polarizability parameterizations even when relevant experimental data are scarce as in the case of electronically excited molecules. Specifically, our scheme assigns the atomic polarizabilities of any given molecule in such a way that its molecular polarizability tensor is well reproduced. We show that our scheme successfully works for various molecules in mimicking dipole responses not only in ground states but also in valence excited states. The electrostatic potential around a molecule with an externally perturbing nearby charge also exhibits a near-quantitative agreement with the reference data from quantum chemical calculations. The limitation of the model with isotropic atoms is also discussed to examine the scope of its applicability.
High-Multipole Excitations of Hydrogen-Like Atoms by Twisted Photons near Phase Singularity
Afanasev, Andrei; Mukherjee, Asmita
2016-01-01
We calculate transition amplitudes and cross sections for excitation of hydrogen-like atoms by the twisted photon states, or photon states with angular momentum projection on the direction of propagation exceeding $\\hbar$. If the target atom is located at distances of the order of atomic size near the phase singularity in the vortex center, the transitions rates into the states with orbital angular momentum $l_f>1$ become comparable with the rates for electric dipole transitions. It is shown that when the transition rates are normalized to the local photon flux, the resulting cross sections for $l_f>1$ are singular near the optical vortex center. Relation to the "quantum core" concept introduced by Berry and Dennis is discussed.
On the combination of a low energy hydrogen atom beam with a cold multipole ion trap
Energy Technology Data Exchange (ETDEWEB)
Borodi, Gheorghe
2008-12-09
The first part of the activities of this thesis was to develop a sophisticated ion storage apparatus dedicated to study chemical processes with atomic hydrogen. The integration of a differentially pumped radical beam source into an existing temperature variable 22- pole trapping machine has required major modifications. Since astrophysical questions have been in the center of our interest, the introduction first gives a short overview of astrophysics and -chemistry. The basics of ion trapping in temperature variable rf traps is well-documented in the literature; therefore, the description of the basic instrument (Chapter 2) is kept rather short. Much effort has been put into the development of an intense and stable source for hydrogen atoms the kinetic energy of which can be changed. Chapter 3 describes this module in detail with emphasis on the integration of magnetic hexapoles for guiding the atoms and special treatments of the surfaces for reducing H-H recombination. Due to the unique sensitivity of the rf ion trapping technique, this instrument allows one to study a variety of reactions of astrochemical and fundamental interest. The results of this work are summarized in Chapter 4. Reactions of CO{sub 2}{sup +} with hydrogen atoms and molecules have been established as calibration standard for in situ determination of H and H{sub 2} densities over the full temperature range of the apparatus (10 K-300 K). For the first time, reactions of H- and D-atoms with the ionic hydrocarbons CH{sup +}, CH{sub 2}{sup +}, and CH{sub 4}{sup +} have been studied at temperatures of interstellar space. A very interesting, not yet fully understood collision system is the interaction of protonated methane with H. The outlook presents some ideas, how to improve the new instrument and a few reaction systems are mentioned which may be studied next. (orig.)
Szmytkowski, Radosław
2016-01-01
The ground state of the Dirac one-electron atom, placed in a weak, static electric field of definite $2^{L}$-polarity, is studied within the framework of the first-order perturbation theory. The Sturmian expansion of the generalized Dirac-Coulomb Green function [R. Szmytkowski, J. Phys. B 30 (1997) 825, erratum: 30 (1997) 2747] is used to derive closed-form analytical expressions for various far-field and near-nucleus static electric multipole susceptibilities of the atom. The far-field multipole susceptibilities --- the polarizabilities $\\alpha_{L}$, electric-to-magnetic cross-susceptibilities $\\alpha_{\\mathrm{E}L\\to\\mathrm{M}(L\\mp1)}$ and electric-to-toroidal-magnetic cross-susceptibilities $\\alpha_{\\mathrm{E}L\\to\\mathrm{T}L}$ --- are found to be expressible in terms of one or two non-terminating generalized hypergeometric functions ${}_{3}F_{2}$ with the unit argument. Counterpart formulas for the near-nucleus multipole susceptibilities --- the electric nuclear shielding constants $\\sigma_{\\mathrm{E}L\\to\\m...
Latina, A
2012-01-01
The electromagnetic radio-frequency (RF) field of accelerating structures and crab-cavities can exhibit transverse field components due to asymmetries in the azimuthal direction of the element geometry. Tracking simulations must be performed to evaluate the impact of such transverse RF deflections on the beam dynamics. In an ultra-relativistic regime where the Panofsky-Wenzel theorem is applicable, these RF deflections can be modeled via a multipolar expansion of the generating RF field similarly to what is done with static magnetic elements. The element implementing such RF multipolar fields has been called RF multipole. In this note we present an analytical formulation of a thin RF multipole Hamiltonian, and we explicitly calculate the RF kick and the elements of its first- and second- order transfer matrices. Also, we present the implementation of the corresponding code in MAD-X, plus some tests of tracking, simplecticity, consistency, and reflected maps that we successfully applied to verify the correctne...
Multipole Expansion in Generalized Electrodynamics
Bonin, C A; Ortega, P H
2016-01-01
In this article we study some classical aspects of Podolsky Electrodynamics in the static regime. We develop the multipole expansion for the theory in both the electrostatic and the magnetostatic cases. We also address the problem of consistently truncating the infinite series associated with the several kinds of multipoles, yielding approximations for the static Podolskian electromagnetic field to any degree of precision required. Moreover, we apply the general theory of multipole expansion to some specific physical problems. In those problems we identify the first terms of the series with the monopole, dipole and quadrupole terms in the generalized theory. We also propose a situation in which Podolsky theory can be experimentally tested.
On the dynamic toroidal multipoles
Fernandez-Corbaton, Ivan; Rockstuhl, Carsten
2015-01-01
Toroidal multipoles are attracting research attention, particularly in the field of metamaterials. They are often understood as a multipolar family in its own right. The dynamic toroidal multipoles emerge from the separation of one of the two transverse multipoles into two parts, referred to as electric and toroidal. Here, we establish that the dynamic toroidal multipolar components of an electric current distribution cannot be determined by measuring the radiation from the source or its coupling to external electromagnetic waves. We analytically show how the split into electric and toroidal parts causes the appearance of non-radiative components in each of the two parts, which cancel when summed back together. The toroidal multipoles do not have an independent meaning with respect to their interaction with the radiation field. Their formal meaning is clear, however. They are the higher order terms of an expansion of the multipolar coefficients of electric parity with respect to the electromagnetic size of th...
Multipole structure of compact objects
Quevedo, Hernando
2016-01-01
We analyze the applications of general relativity in relativistic astrophysics in order to solve the problem of describing the geometric and physical properties of the interior and exterior gravitational and electromagnetic fields of compact objects. We focus on the interpretation of exact solutions of Einstein's equations in terms of their multipole moments structure. In view of the lack of physical interior solutions, we propose an alternative approach in which higher multipoles should be taken into account.
A Guide to Electronic Multipoles in Photon Scattering and Absorption
Lovesey, Stephen William; Balcar, Ewald
2013-02-01
The practice of replacing matrix elements in atomic calculations by those of convenient operators with strong physical appeal has a long history, and in condensed matter physics it is perhaps best known through use of operator equivalents in electron resonance by Elliott and Stevens. Likewise, electronic multipoles, created with irreducible spherical-tensors, to represent charge-like and magnetic-like quantities are widespread in modern physics. Examples in recent headlines include a magnetic charge (a monopole), an anapole (a dipole) and a triakontadipole (a magnetic-like atomic multipole of rank 5). In this communication, we aim to guide the reader through use of atomic, spherical multipoles in photon scattering, and resonant Bragg diffraction and dichroic signals in particular. Applications to copper oxide CuO and neptunium dioxide (NpO2) are described. In keeping with it being a simple guide, there is sparse use in the communication of algebra and expressions are gathered from the published literature and not derived, even when central to the exposition. An exception is a thorough grounding, contained in an Appendix, for an appropriate version of the photon scattering length based on quantum electrodynamics. A theme of the guide is application of symmetry in scattering, in particular constraints imposed on results by symmetry in crystals. To this end, a second Appendix catalogues constraints on multipoles imposed by symmetry in crystal point-groups.
Radiation reaction of multipole moments
Kazinski, P. O.
2007-08-01
A Poincaré-invariant description is proposed for the effective dynamics of a localized system of charged particles in classical electrodynamics in terms of the intrinsic multipole moments of the system. A relativistic-invariant definition for the intrinsic multipole moments of a system of charged particles is given. A new generally covariant action functional for a relativistic perfect fluid is proposed. In the case of relativistic charged dust, it is proven that the description of the problem of radiation reaction of multipole moments by the model of particles is equivalent to the description of this problem by a hydrodynamic model. An effective model is obtained for a pointlike neutral system of charged particles that possesses an intrinsic dipole moment, and the free dynamics of this system is described. The bound momentum of a point dipole is found.
Radiation reaction for multipole moments
Kazinski, P O
2006-01-01
We propose a Poincare-invariant description for the effective dynamics of systems of charged particles by means of intrinsic multipole moments. To achieve this goal we study the effective dynamics of such systems within two frameworks -- the particle itself and hydrodynamical one. We give a relativistic-invariant definition for the intrinsic multipole moments both pointlike and extended relativistic objects. Within the hydrodynamical framework we suggest a covariant action functional for a perfect fluid with pressure. In the case of a relativistic charged dust we prove the equivalence of the particle approach to the hydrodynamical one to the problem of radiation reaction for multipoles. As the particular example of a general procedure we obtain the effective model for a neutral system of charged particles with dipole moment.
Multipole expansion method for supernova neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Duan, Huaiyu; Shalgar, Shashank, E-mail: duan@unm.edu, E-mail: shashankshalgar@unm.edu [Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States)
2014-10-01
We demonstrate a multipole expansion method to calculate collective neutrino oscillations in supernovae using the neutrino bulb model. We show that it is much more efficient to solve multi-angle neutrino oscillations in multipole basis than in angle basis. The multipole expansion method also provides interesting insights into multi-angle calculations that were accomplished previously in angle basis.
Multipole vector solitons in nonlocal nonlinear media.
Kartashov, Yaroslav V; Torner, Lluis; Vysloukh, Victor A; Mihalache, Dumitru
2006-05-15
We show that multipole solitons can be made stable via vectorial coupling in bulk nonlocal nonlinear media. Such vector solitons are composed of mutually incoherent nodeless and multipole components jointly inducing a nonlinear refractive index profile. We found that stabilization of the otherwise highly unstable multipoles occurs below certain maximum energy flow. Such a threshold is determined by the nonlocality degree.
A SMALL UNBALANCED MAGNETRON SPUTTERING SOURCE WITH MULTIPOLE MAGNETIC FIELD ANODE
Institute of Scientific and Technical Information of China (English)
郑思孝; 孙官清; 等
1994-01-01
A small unbalanced magnetron atom source with multipole cusp magnetic field anode is described.The co-axial magnetron rpinciple is extended to the circular planar magnetron atom source,which raises the efficiency of sputtering target area up to 60%.The multipole magnetic field is put in the anode.which makes the unbalanced magnetron atom source run in a higher discharge current at a lower arc voltage condition.Meanwhile.the sputtering atoms through out the anode can be ionized partially,because the electron reaching the anode have to suffer multiple collisons in order to advance across the multipole magnetic field lines in the anode,which enhances the chemical reactivity of the ejecting atoms in film growth and improve the property of film depositing.
Extension of the Multipole Approach to Random Metamaterials
Directory of Open Access Journals (Sweden)
A. Chipouline
2012-01-01
Full Text Available Influence of the short-range lateral disorder in the meta-atoms positioning on the effective parameters of the metamaterials is investigated theoretically using the multipole approach. Random variation of the near field quasi-static interaction between metaatoms in form of double wires is shown to be the reason for the effective permittivity and permeability changes. The obtained analytical results are compared with the known experimental ones.
Vacuum energies and multipole interactions
Rangel, Fabricio Augusto Barone
2016-01-01
In this paper, we present a quantum-field-theoretical description of the interaction between stationary and localized external sources linearly coupled to bosonic fields (specifically, we study models with a scalar and the Maxwell field). We consider external sources that simulate not only point charges but also higher-multipole distributions along D-dimensional branes. Our results complement the ones previously obtained in reference [1].
Electromagnetic multipole fields of neutron stars
Roberts, W. J.
1979-01-01
A formalism is developed for treating general multipole electromagnetic fields of neutron stars. The electric multipoles induced in a neutron star by its rotation with an arbitrary magnetic multipole at its center are presented. It is shown how to express a family of off-centered multipoles having the same l weight as an infinite array of centered multipoles of increasing l weight referred to the rotational axis. General expressions are given for the linear momentum present in the superposition of arbitrary multipole fields, and the results are combined to compute the radiation rate of linear momentum by an off-centered dipole to zeroth order in the parameter Omega x R/c. The general Deutsch (1955) solution is then rederived in a clear consistent manner, and some minor additions and corrections are provided.
Multipole surface solitons in layered thermal media
Kartashov, Yaroslav V; Torner, Lluis
2008-01-01
We address the existence and properties of multipole solitons localized at a thermally insulating interface between uniform or layered thermal media and a linear dielectric. We find that in the case of uniform media, only surface multipoles with less than three poles can be stable. In contrast, we reveal that periodic alternation of the thermo-optic coefficient in layered thermal media makes possible the stabilization of higher order multipoles.
Multipole Moments of numerical spacetimes
Pappas, George
2012-01-01
In this article we present some recent results on identifying correctly the relativistic multipole moments of numerically constructed spacetimes, and the consequences that this correction has on searching for appropriate analytic spacetimes that can approximate well the previously mentioned numerical spacetimes. We also present expressions that give the quadrupole and the spin octupole as functions of the spin parameter of a neutron star for various equations of state and in a range of masses for every equation of state used. These results are relevant for describing the exterior spacetime of rotating neutron stars that are made up of matter obeying realistic equations of state.
Energy Technology Data Exchange (ETDEWEB)
Wang, Z.; Lupo, J.; Patnaik, S.S.; McKenney, A.; Pachter, R.
1999-07-01
The Fast Multipole Method (FMM) offers an efficient way (order O(N)) to handle long range electrostatic interactions, thus enabling more realistic molecular dynamics simulations of large molecular systems. The performance of the fast molecular dynamics (FMD) code, a parallel MD code being developed in the group, using the three-dimensional fast multipole method, shows a good speedup. The application to the full atomic-scale molecular dynamics simulation of a liquid crystalline droplet of 4-n-pentyl-4{prime}-cyanobiphenyl (5CB) molecules, of size 35,872 atoms, shows strong surface effects on various orientational order parameters.
Description of complex time series by multipoles
DEFF Research Database (Denmark)
Lewkowicz, M.; Levitan, J.; Puzanov, N.
2002-01-01
We present a new method to describe time series with a highly complex time evolution. The time series is projected onto a two-dimensional phase-space plot which is quantified in terms of a multipole expansion where every data point is assigned a unit mass. The multipoles provide an efficient...... characterization of the original time series....
Investigation of Multipole Electrostatics in Hydration Free Energy Calculations
Shi, Yue; Wu, Chuanjie; Ponder, Jay W.; Ren, Pengyu
2010-01-01
Hydration free energy (HFE) is generally used for evaluating molecular solubility, which is an important property for pharmaceutical and chemical engineering processes. Accurately predicting HFE is also recognized as one fundamental capability of molecular mechanics force field. Here we present a systematic investigation on HFE calculations with AMOEBA polarizable force field at various parameterization and simulation conditions. The HFEs of seven small organic molecules have been obtained alchemically using the Bennett Acceptance Ratio (BAR) method. We have compared two approaches to derive the atomic multipoles from quantum mechanical (QM) calculations: one directly from the new distributed multipole analysis (DMA) and the other involving fitting to the electrostatic potential around the molecules. Wave functions solved at the MP2 level with four basis sets (6-311G*, 6-311++G(2d,2p), cc-pVTZ, and aug-cc-pVTZ) are used to derive the atomic multipoles. HFEs from all four basis sets show a reasonable agreement with experimental data (root mean square error 0.63 kcal/mol for aug-ccpVTZ). We conclude that aug-cc-pVTZ gives the best performance when used with AMOEBA, and 6-311++G(2d,2p) is comparable but more efficient for larger systems. The results suggest that the inclusion of diffuse basis functions is important for capturing intermolecular interactions. The effect of long-range correction to van der Waals interaction on the hydration free energies is about 0.1 kcal/mol when the cutoff is 12Å, and increases linearly with the number of atoms in the solute/ligand. In addition, we also discussed the results from a hybrid approach that combines polarizable solute with fixed-charge water in the hydration free energy calculation. PMID:20925089
Tailoring the multipoles in THz toroidal metamaterials
Cong, Longqing; Srivastava, Yogesh Kumar; Singh, Ranjan
2017-08-01
The multipoles play a significant role in determining the resonant behavior of subwavelength resonators that form the basis of metamaterial and plasmonic systems. Here, we study the impact of multipoles including toroidal dipole on the resonance intensity and linewidth of the fundamental inductive-capacitance (LC) resonance of a metamaterial array. The dominant multipoles that strongly contribute to the resonances are tailored by spatial rearrangement of the neighboring resonators such that the mutual interactions between the magnetic, electric, and toroidal configurations lead to enormous change in the linewidth as well as the resonance intensity of the LC mode. Manipulation of the multipoles in a metamaterial array provides a general strategy for the optimization of the quality factor of metamaterial resonances, which is fundamental to its applications in broad areas of sensing, lasing and nonlinear optics where stronger field confinement plays a significant role.
Multipole electron-density modelling of synchrotron powder diffraction data: the case of diamond
DEFF Research Database (Denmark)
Svendsen, H.; Overgaard, J.; Busselez, R.;
2010-01-01
Accurate structure factors are extracted from synchrotron powder diffraction data measured on crystalline diamond based on a novel multipole model division of overlapping reflection intensities. The approach limits the spherical-atom bias in structure factors extracted from overlapping powder data...... parameter. This directly exposes a correlation between electron density and thermal parameters even for a light atom such as carbon, and it also underlines that in organic systems proper deconvolution of thermal motion is important for obtaining correct static electron densities....
A pragmatic overview of fast multipole methods
Energy Technology Data Exchange (ETDEWEB)
Strickland, J.H.; Baty, R.S.
1995-12-01
A number of physics problems can be modeled by a set of N elements which have pair-wise interactions with one another. A direct solution technique requires computational effort which is O(N{sup 2}). Fast multipole methods (FMM) have been widely used in recent years to obtain solutions to these problems requiring a computational effort of only 0 (N lnN) or O (N). In this paper we present an overview of several variations of the fast multipole method along with examples of its use in solving a variety of physical problems.
Simulation of Monopole and Multipole Seismoelectric Logging
Directory of Open Access Journals (Sweden)
Zhiwen Cui
2011-01-01
Full Text Available In a fluid-saturated porous formation, acoustics and electromagnetic waves are coupled based on Pride seismoelectric theory. An exact treatment of the nonaxisymmetric seismoelectric field excited by acoustic multipole sources is presented. The frequency wavenumber domain representations of the acoustic field and associated seismoelectric field due to acoustic multipole sources are formulated. The full waveforms of acoustic waves and electric and magnetic fields in the time domain propagation in borehole are simulated by using discrete wave number integration, and frequency versus axial-wave number responses are presented and analyzed.
Suppressing CMB low multipoles with ISW effect
Das, Santanu
2013-01-01
Recent results of Planck data reveal that the power in the low multipoles of the CMB angular power spectrum, approximately up to $l=30$, is significantly lower than the theoretically predicted in the best fit $\\Lambda$CDM model. In this paper we investigate the possibility of invoking the Integrated Sachs-Wolfe (ISW) effect to explain this power deficit at low multipoles. The ISW effect that originates from the late time expansion history of the universe is rich in possibilities given the limited understanding of the origin of dark energy (DE). It is a common understanding that the ISW effect adds to the power at the low multipoles of the CMB angular power spectrum. In this paper we carry out an analytic study to show that there are some expansion histories in which the ISW effect, instead of adding power, provides negative contribution to the power at low multipoles. Guided by the analytic study, we present examples of the features required in the late time expansion history of the universe that could explai...
Multipole Analysis of Circular Cylindircal Magnetic Systems
Energy Technology Data Exchange (ETDEWEB)
Selvaggi, Jerry P. [Rensselaer Polytechnic Inst., Troy, NY (United States)
2005-12-01
This thesis deals with an alternate method for computing the external magnetic field from a circular cylindrical magnetic source. The primary objective is to characterize the magnetic source in terms of its equivalent multipole distribution. This multipole distribution must be valid at points close to the cylindrical source and a spherical multipole expansion is ill-equipped to handle this problem; therefore a new method must be introduced. This method, based upon the free-space Green's function in cylindrical coordinates, is developed as an alternative to the more familiar spherical harmonic expansion. A family of special functions, called the toroidal functions or Q-functions, are found to exhibit the necessary properties for analyzing circular cylindrical geometries. In particular, the toroidal function of zeroth order, which comes from the integral formulation of the free-space Green's function in cylindrical coordinates, is employed to handle magnetic sources which exhibit circular cylindrical symmetry. The toroidal functions, also called Q-functions, are the weighting coefficients in a ''Fourier series-like'' expansion which represents the free-space Green's function. It is also called a toroidal expansion. This expansion can be directly employed in electrostatic, magnetostatic, and electrodynamic problems which exhibit cylindrical symmetry. Also, it is shown that they can be used as an alternative to the Elliptic integral formulation. In fact, anywhere that an Elliptic integral appears, one can replace it with its corresponding Q-function representation. A number of problems, using the toroidal expansion formulation, are analyzed and compared to existing known methods in order to validate the results. Also, the equivalent multipole distribution is found for most of the solved problems along with its corresponding physical interpretation. The main application is to characterize the external magnetic field due to a six
Modeling and Optimizing RF Multipole Ion Traps
Fanghaenel, Sven; Asvany, Oskar; Schlemmer, Stephan
2016-06-01
Radio frequency (rf) ion traps are very well suited for spectroscopy experiments thanks to the long time storage of the species of interest in a well defined volume. The electrical potential of the ion trap is determined by the geometry of its electrodes and the applied voltages. In order to understand the behavior of trapped ions in realistic multipole traps it is necessary to characterize these trapping potentials. Commercial programs like SIMION or COMSOL, employing the finite difference and/or finite element method, are often used to model the electrical fields of the trap in order to design traps for various purposes, e.g. introducing light from a laser into the trap volume. For a controlled trapping of ions, e.g. for low temperature trapping, the time dependent electrical fields need to be known to high accuracy especially at the minimum of the effective (mechanical) potential. The commercial programs are not optimized for these applications and suffer from a number of limitations. Therefore, in our approach the boundary element method (BEM) has been employed in home-built programs to generate numerical solutions of real trap geometries, e.g. from CAD drawings. In addition the resulting fields are described by appropriate multipole expansions. As a consequence, the quality of a trap can be characterized by a small set of multipole parameters which are used to optimize the trap design. In this presentation a few example calculations will be discussed. In particular the accuracy of the method and the benefits of describing the trapping potentials via multipole expansions will be illustrated. As one important application heating effects of cold ions arising from non-ideal multipole fields can now be understood as a consequence of imperfect field configurations.
Institute of Scientific and Technical Information of China (English)
刘洪毓
2007-01-01
Atoms(原子)are all around us.They are something like the bricks (砖块)of which everything is made. The size of an atom is very,very small.In just one grain of salt are held millions of atoms. Atoms are very important.The way one object acts depends on what
On the evaluation of molecular dipole moments from multipole refinement of X-ray diffraction data
Abramov, Yu. A.; Volkov, A. V.; Coppens, P.
1999-09-01
Lack of physical constraints in the purely mathematical multipole refinement model can lead to basis set overlap errors in the evaluation of static molecular properties from X-ray diffraction data. For the molecular dipole moment, the error is large for several of the crystals tested in this study: DL-histidine, DL-proline, p-nitroaniline and p-amino- p'-nitrobiphenyl. Two restricted models are tested. In the first, atomic charges are constrained at κ-refinement values, while in the second κ'-values based on multipole refinements of theoretical ab-initio structure factors are used to reduce the flexibility of the model. Both models provide a more localized description of the pseudo atoms compared with an unrestricted refinement, but the κ'-restricted model gives a more consistent representation of the molecular dipole moments and superior agreement with the theoretical deformation density for DL-histidine.
Institute of Scientific and Technical Information of China (English)
黄时中; 李增
2012-01-01
在Tang和Chan所给出的氢原子的2l-极动态极化率的微分表达式的基础上,进一步导出了氢原子电多极动态极化率的解析表达式,从而完全解决了氢原子动态极化率的计算问题.应用此解析表达式,首次计算了氢原子H(2s)-H(2s)-H(2s)体系的三体相互作用系数.%An analytic expression for the 2l-pole dynamic polarizability of hydrogen atom in an arbitrary state is derived from a differential expression obtained by Tang and Chan,and the problem of calculating the 2l-pole dynamic polarizability of hydrogen is solved.As an application,new three-body van der Waals dispersion coefficients for the H (2s)-H(2s)-H (2s) system are calculated from integrals of products of the dynamic polarizabilities of the interacting atoms.
Multipole moments for embedding potentials
DEFF Research Database (Denmark)
Nørby, Morten Steen; Olsen, Jógvan Magnus Haugaard; Kongsted, Jacob
2016-01-01
Polarizable quantum mechanical (QM)/molecular mechanics (MM)-embedding methods are currently among the most promising methods for computationally feasible, yet reliable, production calculations of localized excitations and molecular response properties of large molecular complexes, such as proteins...... extended with site polarizabilities including internal charge transfer terms. We present a new way of dealing with well-known problems in relation to the use of basis sets with diffuse functions in conventional atomic allocation algorithms, avoiding numerical integration schemes. Using this approach, we...
Multipole Traps as Tools in Environmental Studies
Mihalcea, Bogdan M; Giurgiu, Liviu C; Groza, Andreea; Surmeian, Agavni; Ganciu, Mihai; Filinov, Vladimir; Lapitsky, Dmitry; Deputatova, Lidiya; Vasilyak, Leonid; Pecherkin, Vladimir; Vladimirov, Vladimir; Syrovatka, Roman
2015-01-01
Trapping of microparticles, nanoparticles and aerosols is an issue of major interest for physics and chemistry. We present a setup intended for microparticle trapping in multipole linear Paul trap geometries, operating under Standard Ambient Temperature and Pressure (SATP) conditions. A 16-electrode linear trap geometry has been designed and tested, with an aim to confine a larger number of particles with respect to quadrupole traps and thus enhance the signal to noise ratio, as well as to study microparticle dynamical stability in electrodynamic fields. Experimental tests and numerical simulations suggest that multipole traps are very suited for high precision mass spectrometry measurements in case of different microparticle species or to identify the presence of certain aerosols and polluting agents in the atmosphere. Particle traps represent versatile tools for environment monitoring or for the study of many-body Coulomb systems and dusty plasmas.
Multipole invariants and non-Gaussianity
Land, K; Land, Kate; Magueijo, Joao
2004-01-01
We propose a framework for separating the information contained in the CMB multipoles, $a_{\\ell m}$, into its algebraically independent components. Thus we cleanly separate information pertaining to the power spectrum, non-Gaussianity and preferred axis effects. The formalism builds upon the recently proposed multipole vectors (Copi, Huterer & Starkman 2003; Schwarz & al 2004; Katz & Weeks 2004), and we elucidate a few features regarding these vectors, namely their lack of statistical independence for a Gaussian random process. In a few cases we explicitly relate our proposed invariants to components of the $n$-point correlation function (power spectrum, bispectrum). We find the invariants' distributions using a mixture of analytical and numerical methods. We also evaluate them for the co-added WMAP first year map.
Multipole solutions in metric-affine gravity
Socorro, J; Macías, A; Mielke, E W; Socorro, José; Lämmerzahl, Claus; Macías, Alfredo; Mielke, Eckehard W.
1998-01-01
Above Planck energies, the spacetime might become non--Riemannian, as it is known fron string theory and inflation. Then geometries arise in which nonmetricity and torsion appear as field strengths, side by side with curvature. By gauging the affine group, a metric affine gauge theory emerges as dynamical framework. Here, by using the harmonic map ansatz, a new class of multipole like solutions in the metric affine gravity theory (MAG) is obtained.
Poloidal OHMIC heating in a multipole
Energy Technology Data Exchange (ETDEWEB)
Holly, D.J.
1982-01-01
The feasibility of using poloidal currents to heat plasmas confined by a multipole field has been examined experimentaly in Tokapole II. The machine is operated as a toroidal octupole, with a time-varying toroidal magnetic field driving poloidal plasma currents I/sub plasma/ - 20 kA to give densities n/sub e/ - 10/sup 13/ cm/sup -3/ and temperatures T/sub e/ - 30 eV.
Optimization of RF multipole ion trap geometries
Fanghänel, Sven; Asvany, Oskar; Schlemmer, Stephan
2017-02-01
Radio-frequency (rf) traps are ideal places to store cold ions for spectroscopic experiments. Specific multipole configurations are suited best for different applications but have to be modified to allow e.g. for a proper overlap of a laser beam waist with the ion cloud. Therefore the corresponding trapping fields should be shaped accordingly. To achieve this goal highly accurate electrical potentials of rf multipole traps and the resulting effective trapping potentials are calculated using the boundary element method (BEM). These calculations are used to evaluate imperfections and to optimize the field geometry. For that purpose the complex fields are reduced to a small set of multipole expansion coefficients. Desirable values for these coefficients are met by systematic changes of real trap dimensions from CAD designs. The effect of misalignment of a linear quadrupole, the optimization of an optically open Paul trap, the influence of steering electrodes (end electrode and ring electrode) on a 22-pole ion trap and the effect of the micro motion on the lowest reachable temperatures in such a trap are discussed.
Least Square Approximation by Linear Combinations of Multi(Poles).
1983-04-01
ID-R134 069 LEAST SQUARE APPROXIMATION BY LINEAR COMBINATIONS OF i/i MULTI(POLES). 1U OHIO STATE UNIV COLUMBUS DEPT OF GEODETIC SCIENCE AND SURVEY...TR-83-0 117 LEAST SQUARE APPROXIMATION BY LINEAR COMBINATIONS OF (MULTI)POLES WILLI FREEDEN DEPARTMENT OF GEODETIC SCIENCE AND SURVEYING THE OHIO...Subtitle) S. TYPE OF REPORT & PERIOD COVERED LEAST SQUARE APPROXIMATION BY LINEAR Scientific Report No. 3 COMBINATIONS OF (MULTI)POLES 6. PERFORMING ORG
Complex space multipole theory for scattering and diffraction problems
Lindell, Ismo V.; Nikoskinen, Keijo I.
1987-01-01
Classical multipole theory can be extended to multipoles located in complex space and applied in scattering and diffraction problems with the advantage that, if the point of the multipole is correctly chosen, the first term may give an order of magnitude better approximation to the source than when the multipole is in real space. The basic theory, given elsewhere, is presented here in a more straightforward manner and the improvement in radiation pattern is demonstrated for sources of constant polarization. Applications on scattering by spheroidal dielectric bodies and diffraction by a dielectric half-space are discussed.
The Soft Cumulative Constraint
Petit, Thierry
2009-01-01
This research report presents an extension of Cumulative of Choco constraint solver, which is useful to encode over-constrained cumulative problems. This new global constraint uses sweep and task interval violation-based algorithms.
Wu, Xiongwu; Pickard, Frank C.; Brooks, Bernard R.
2016-10-01
Isotropic periodic sum (IPS) is a method to calculate long-range interactions based on the homogeneity of simulation systems. By using the isotropic periodic images of a local region to represent remote structures, long-range interactions become a function of the local conformation. This function is called the IPS potential; it folds long-ranged interactions into a short-ranged potential and can be calculated as efficiently as a cutoff method. It has been demonstrated that the IPS method produces consistent simulation results, including free energies, as the particle mesh Ewald (PME) method. By introducing the multipole homogeneous background approximation, this work derives multipole IPS potentials, abbreviated as IPSMm, with m being the maximum order of multipole interactions. To efficiently calculate the multipole interactions in Cartesian space, we propose a vector relation that calculates a multipole tensor as a dot product of a radial potential vector and a directional vector. Using model systems with charges, dipoles, and/or quadrupoles, with and without polarizability, we demonstrate that multipole interactions of order m can be described accurately with the multipole IPS potential of order 2 or m - 1, whichever is higher. Through simulations with the multipole IPS potentials, we examined energetic, structural, and dynamic properties of the model systems and demonstrated that the multipole IPS potentials produce very similar results as PME with a local region radius (cutoff distance) as small as 6 Å.
Kelvin transformation and inverse multipoles in electrostatics
Amaral, R L P G; Lemos, N A
2016-01-01
The inversion in the sphere or Kelvin transformation, which exchanges the radial coordinate for its inverse, is used as a guide to relate distinct electrostatic problems with dual features. The exact solution of some nontrivial problems are obtained through the mapping from simple highly symmetric systems. In particular, the concept of multipole expansion is revisited from a point of view opposed to the usual one: the sources are distributed in a region far from the origin while the electrostatic potential is described at points close to it.
Multipole stack for the 4 rings of the PS Booster
1976-01-01
The PS Booster (originally 800 MeV, now 1.4 GeV) saw first beam in 1972, routine operation began in 1973. The strive for ever higher intensities required the addition of multipoles. Manufacture of 8 stacks of multipoles was launched in 1974, for installation in 1976. For details, see 7511120X.
The Effect of Multipole-Enhanced Diffusion on the Joule Heating of a Cold Non-Neutral Plasma
Chapman, Steven Francis
One proposed technique for trapping anti-atoms is to superimpose a Ioffe-Pritchard style magnetic-minimum neutral trap on a standard Penning trap used to trap the charged atomic constituents. Adding a magnetic multipole field in this way removes the azimuthal symmetry of the ideal Penning trap and introduces a new avenue for radial diffusion. Enhanced diffusion will lead to increased Joule heating of a non-neutral plasma, potentially adversely affecting the formation rate of anti-atoms and increasing the required trap depth. We present a model of this effect, along with an approach to minimizing it, with comparison to measurements from an intended anti-atom trap.
Reflection and refraction of multipole radiation by an interface.
Arnoldus, Henk F
2005-01-01
Reflection and refraction of electromagnetic multipole radiation by an interface is studied. The multipole can be electric or magnetic and is of arbitrary order (dipole, quadrupole). From the angular spectrum representation of the radiation emitted by the multipole, I have obtained the angular spectrum representations of the reflected and transmitted fields, which involve the Fresnel reflection and transmission coefficients. The intensity distribution in the far field is evaluated with the method of stationary phase. The result is very simple in appearance and can be expressed in terms of two auxiliary functions of a complex variable. By exchanging the Fresnel coefficients for s and p polarization, the result for an electric multipole can be obtained from the result for a magnetic multipole.
A fast multipole transformation for global climate calculations
Energy Technology Data Exchange (ETDEWEB)
Holmes, J.A.; Wang, Z.; Drake, J.B.; Lyon, B.F.; Chen, W.T.
1996-01-01
A fast multipole transformation is adapted to the evaluation of summations that occur in global climate calculations when transforming between spatial and spherical harmonic representations. For each summation, the timing of the fast multipole transformation scales linearly with the number of latitude gridpoints, but the timing for direct evaluations scales quadratically. In spite of a larger computational overhead, this scaling advantage renders the fast multipole method faster than direct evaluation for transformations involving greater than approximately 300 to 500 gridpoints. Convergence of the fast multipole transformation is accurate to machine precision. As the resolution in global climate calculations continues to increase, an increasingly large fraction of the computational work involves the transformation between spatial and spherical harmonic representations. The fast multipole transformation offers a significant reduction in computational time for these high-resolution cases.
Microscopic Theory of Multipole Ordering in f-Electron Systems
Directory of Open Access Journals (Sweden)
Takashi Hotta
2012-01-01
Full Text Available A microscopic framework to determine multipole ordering in f-electron systems is provided on the basis of the standard quantum field theory. For the construction of the framework, a seven-orbital Hubbard Hamiltonian with strong spin-orbit coupling is adopted as a prototype model. A type of multipole and ordering vector is determined from the divergence of multipole susceptibility, which is evaluated in a random phase approximation. As an example of the application of the present framework, a multipole phase diagram on a three-dimensional simple cubic lattice is discussed for the case of n=2, where n denotes the average f-electron number per site. Finally, future problems concerning multipole ordering and fluctuations are briefly discussed.
The Multipole Vectors of WMAP, and their frames and invariants
Land, K; Land, Kate; Magueijo, Joao
2005-01-01
We investigate the Statistical Isotropy and Gaussianity of the CMB fluctuations, using a set of multipole vector functions capable of separating these two issues. In general a multipole is broken into a frame and $2\\ell-3$ ordered invariants. The multipole frame is found to be suitably sensitive to galactic cuts. We then apply our method to real WMAP datasets; a coadded masked map, the Internal Linear Combinations map, and Wiener filtered and cleaned maps. Taken as a whole, multipoles in the range $\\ell=2-10$ or $\\ell=2-20$ show consistency with statistical isotropy, as proved by the Kolmogorov test applied to the frame's Euler angles. This result in {\\it not} inconsistent with previous claims for a preferred direction in the sky for $\\ell=2,...5$. The multipole invariants also show overall consistency with Gaussianity apart from a few anomalies of limited significance (98%), listed at the end of this paper.
Multipole Stack for the 800 MeV PS Booster
1975-01-01
The 800 MeV PS Booster had seen first beam in its 4 superposed rings in 1972, routine operation began in 1973. In the strive for ever higher beam intensities, the need for additional multipole lenses became evident. After detailed studies, the manufacture of 8 stacks of multipoles was launched in 1974. Each stack consists of 4 superposed multipoles and each multipole has 4 concentric shells. From the innermost to the outermost shell, Type A contains octupole, skew-octupole, sextupole, skew-sextupole. Type B contains skew-octupole, skew-sextupole, vertical dipole, horizontal dipole. Completion of installation in 1976 opened the way to higher beam intensities. M. Battiaz is seen here with a multipole stack and its many electrical connections.
Multipole charge conservation and implications on electromagnetic radiation
Seraj, Ali
2016-01-01
It is shown that conserved charges associated with a specific subclass of gauge symmetries of Maxwell electrodynamics are proportional to the well known electric multipole moments. The symmetries are residual gauge transformations surviving after fixing the Lorenz gauge, and have nontrivial charge. These "Multipole charges" receive contributions both from the charged matter and electromagnetic fields. The former is nothing but the electric multipole moment of the source. In a stationary configuration, there is a novel equipartition relation between the two contributions. The multipole charge, while conserved, can freely interpolate between the source and the electromagnetic field, and therefore can be propagated with the radiation. Using the multipole charge conservation, we obtain infinite number of constraints over the radiation produced by the dynamics of charged matter.
Gniewek, Piotr
2016-01-01
The conventional surface integral formula $J_{\\rm surf}[\\Phi]$ and an alternative volume integral formula $J_{\\rm var}[\\Phi]$ are used to compute the asymptotic exchange splitting of the interaction energy of the hydrogen atom and a proton employing the primitive function $\\Phi$ in the form of its truncated multipole expansion. Closed-form formulas are obtained for the asymptotics of $J_{\\rm surf}[\\Phi_N]$ and $J_{\\rm var}[\\Phi_N]$, where $\\Phi_N$ is the multipole expansion of $\\Phi$ truncated after the $1/R^N$ term, $R$ being the internuclear separation. It is shown that the obtained sequences of approximations converge to the exact results with the rate corresponding to the convergence radius equal to 2 and 4 when the surface and the volume integral formulas are used, respectively. When the multipole expansion of a truncated, $K$th order polarization function is used to approximate the primitive function the convergence radius becomes equal to unity in the case of $J_{\\textrm{var}}[\\Phi]$. At low order the ...
Bereau, Tristan; von Lilienfeld, O Anatole
2015-01-01
Accurate predictions of van der Waals forces require faithful models of dispersion, permanent and induced multipole-moments, as well as penetration and repulsion. We introduce a universal combined physics- and data-driven model of dispersion and multipole-moment contributions, respectively. Atomic multipoles are estimated "on-the-fly" for any organic molecule in any conformation using a machine learning approach trained on quantum chemistry results for tens of thousands of atoms in varying chemical environments drawn from thousands of organic molecules. Globally neutral, cationic, and anionic molecular charge states can be treated with individual models. Dispersion interactions are included via recently-proposed classical many-body potentials. For nearly one thousand intermolecular dimers, this approximate van der Waals model is found to reach an accuracy similar to that of state-of-the-art force fields, while bypassing the need for parametrization. Estimates of cohesive energies for the benzene crystal confi...
United polarizable multipole water model for molecular mechanics simulation
Energy Technology Data Exchange (ETDEWEB)
Qi, Rui; Wang, Qiantao; Ren, Pengyu, E-mail: pren@mail.utexas.edu [Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Wang, Lee-Ping; Pande, Vijay S. [Department of Chemistry, Stanford University, Stanford, California 94305 (United States)
2015-07-07
We report the development of a united AMOEBA (uAMOEBA) polarizable water model, which is computationally 3–5 times more efficient than the three-site AMOEBA03 model in molecular dynamics simulations while providing comparable accuracy for gas-phase and liquid properties. In this coarse-grained polarizable water model, both electrostatic (permanent and induced) and van der Waals representations have been reduced to a single site located at the oxygen atom. The permanent charge distribution is described via the molecular dipole and quadrupole moments and the many-body polarization via an isotropic molecular polarizability, all located at the oxygen center. Similarly, a single van der Waals interaction site is used for each water molecule. Hydrogen atoms are retained only for the purpose of defining local frames for the molecular multipole moments and intramolecular vibrational modes. The parameters have been derived based on a combination of ab initio quantum mechanical and experimental data set containing gas-phase cluster structures and energies, and liquid thermodynamic properties. For validation, additional properties including dimer interaction energy, liquid structures, self-diffusion coefficient, and shear viscosity have been evaluated. The results demonstrate good transferability from the gas to the liquid phase over a wide range of temperatures, and from nonpolar to polar environments, due to the presence of molecular polarizability. The water coordination, hydrogen-bonding structure, and dynamic properties given by uAMOEBA are similar to those derived from the all-atom AMOEBA03 model and experiments. Thus, the current model is an accurate and efficient alternative for modeling water.
Limitation of Multipoles in BOSS DR12 results
Lee, Seokcheon
2016-01-01
Recently, the power spectrum (PS) multipoles using the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 12 (DR12) sample are analyzed \\cite{160703150}. Even though the based model for the analysis is the so-called TNS quasi-linear model including the multipole up to the eighth order in the window function \\cite{TNS}, the analysis provides the multipoles up to the hexadecapole. Thus, one might be able to recover the galaxy PS by using the combination of multipoles to investigate the cosmology \\cite{0407214}. We provide the analytic form of this combination of multipoles of the quasi-linear PS including the Fingers of God (FoG) effect to recover the PS at the linear regime. In order to confirm the consistency of the multipole data, we compare the multipole ratios of the linear theory including the FoG effect with those of observation. The data of the ratio of quadrupole to monopole is consistent with that of the linear theory prediction even though the current observational error is too large to dist...
Scoring multipole electrostatics in condensed-phase atomistic simulations.
Bereau, Tristan; Kramer, Christian; Monnard, Fabien W; Nogueira, Elisa S; Ward, Thomas R; Meuwly, Markus
2013-05-09
Permanent multipoles (MTPs) embody a natural extension to common point-charge (PC) representations in atomistic simulations. In this work, we propose an alternative to the computationally expensive MTP molecular dynamics simulations by running a simple PC simulation and later reevaluate-"score''-all energies using the more detailed MTP force field. The method, which relies on the assumption that the PC and MTP force fields generate closely related phase spaces, is accomplished by enforcing identical sets of monopoles between the two force fields-effectively highlighting the higher MTP terms as a correction to the PC approximation. We first detail our consistent parametrization of the electrostatics and van der Waals interactions for the two force fields. We then validate the method by comparing the accuracy of protein-ligand binding free energies from both PC and MTP-scored representations with experimentally determined binding constants obtained by us. Specifically, we study the binding of several arylsulfonamide ligands to human carbonic anhydrase II. We find that both representations yield an accuracy of 1 kcal/mol with respect to experiment. Finally, we apply the method to rank the energetic contributions of individual atomic MTP coefficients for molecules solvated in water. All in all, MTP scoring is a computationally appealing method that can provide insight into the multipolar electrostatic interactions of condensed-phase systems.
Multipole moments of bumpy black holes
Vigeland, Sarah J
2010-01-01
General relativity predicts the existence of black holes, compact objects whose spacetimes depend on only their mass and spin (the famous "no hair" theorem). As various observations probe deeper into the strong fields of black hole candidates, it is becoming possible to test this prediction. Previous work suggested that such tests can be performed by measuring whether the multipolar structure of black hole candidates has the form that general relativity demands, and introduced a family of "bumpy black hole" spacetimes to be used for making these measurements. These spacetimes are black holes with the "wrong" multipoles, where the deviation from general relativity depends on the spacetime's "bumpiness." In this paper, we show how to compute the Geroch-Hansen moments of a bumpy black hole, demonstrating that there is a clean mapping between the deviations used in the bumpy black hole formalism and the Geroch-Hansen moments. We also extend our previous results to define bumpy black holes whose {\\it current} mome...
Fast Multipole-Based Elliptic PDE Solver and Preconditioner
Ibeid, Huda
2016-12-07
Exascale systems are predicted to have approximately one billion cores, assuming Gigahertz cores. Limitations on affordable network topologies for distributed memory systems of such massive scale bring new challenges to the currently dominant parallel programing model. Currently, there are many efforts to evaluate the hardware and software bottlenecks of exascale designs. It is therefore of interest to model application performance and to understand what changes need to be made to ensure extrapolated scalability. Fast multipole methods (FMM) were originally developed for accelerating N-body problems for particle-based methods in astrophysics and molecular dynamics. FMM is more than an N-body solver, however. Recent efforts to view the FMM as an elliptic PDE solver have opened the possibility to use it as a preconditioner for even a broader range of applications. In this thesis, we (i) discuss the challenges for FMM on current parallel computers and future exascale architectures, with a focus on inter-node communication, and develop a performance model that considers the communication patterns of the FMM for spatially quasi-uniform distributions, (ii) employ this performance model to guide performance and scaling improvement of FMM for all-atom molecular dynamics simulations of uniformly distributed particles, and (iii) demonstrate that, beyond its traditional use as a solver in problems for which explicit free-space kernel representations are available, the FMM has applicability as a preconditioner in finite domain elliptic boundary value problems, by equipping it with boundary integral capability for satisfying conditions at finite boundaries and by wrapping it in a Krylov method for extensibility to more general operators. Compared with multilevel methods, FMM is capable of comparable algebraic convergence rates down to the truncation error of the discretized PDE, and it has superior multicore and distributed memory scalability properties on commodity
Multipole Matrix Elements for Dh-Systems and Their Asymptotics
Tarasov, V. F.
A “DH-system” is defined as a multidimensional hydrogen atom (or its one-particle analogue), D≥1. Investigating many Coulomb problems in ℝD it is necessary to know exact analytical expressions of multipole matrix elements D for DH-systems, where q=(N, µ) is a set of parameters, N —"principal” and µ — "orbital” quantum numbers. The paper deals with the new method for the evaluation of similar matrix elements using new properties of Appell’s function F2(x, y) to the vicinity of the singular point (1, 1). Such approach allows: 1) to get exact analytical expressions of these matrix elements (considering the selection rules) by means of Appell’s F2 (or Clausen’s 3F2) functions; 2) to reveal “latent” symmetry of diagonal matrix elements with respect to the point k0=-3/2, the above symmetry is connected with the property of Appell’s function F2 (1,1) mirror-like symmetry; 3) to find (exact) asymptotics of the off-diagonal matrix elements in terms of Horn’s function ψ1 (x, y); 4) to prove that the orthogonality of radial functions fNµ (D, r) over N and μ for DH-systems is connected with the properties of Appell’s F2 function to the vicinity of the singular point (1, 1), it generalizes the known result for 3H-atom by Pasternack and Sternheimer, J. Math. Phys. 3, 1280 (1962).
Multipole Matrix of Green Function of Laplace Equation
Makuch, K.; Górka, P.
Multipole matrix elements of Green function of Laplace equation are calculated. The multipole matrix elements of Green function in electrostatics describe potential on a sphere which is produced by a charge distributed on the surface of a different (possibly overlapping) sphere of the same radius. The matrix elements are defined by double convolution of two spherical harmonics with the Green function of Laplace equation. The method we use relies on the fact that in the Fourier space the double convolution has simple form. Therefore we calculate the multipole matrix from its Fourier transform. An important part of our considerations is simplification of the three dimensional Fourier transformation of general multipole matrix by its rotational symmetry to the one-dimensional Hankel transformation.
QCD Multipole Expansion and Hadronic Transitions in Heavy Quarkonium Systems
Institute of Scientific and Technical Information of China (English)
KUANG Yu-ping
2006-01-01
We review the developments of the multipole expansion approach in quantum chromodynamics and its applications to hadronic transitions and some radiative decays of heavy quarkonia.Theoretical predictions are compared with updated experimental results.
Point charges optimally placed to represent the multipole expansion of charge distributions.
Directory of Open Access Journals (Sweden)
Ramu Anandakrishnan
Full Text Available We propose an approach for approximating electrostatic charge distributions with a small number of point charges to optimally represent the original charge distribution. By construction, the proposed optimal point charge approximation (OPCA retains many of the useful properties of point multipole expansion, including the same far-field asymptotic behavior of the approximate potential. A general framework for numerically computing OPCA, for any given number of approximating charges, is described. We then derive a 2-charge practical point charge approximation, PPCA, which approximates the 2-charge OPCA via closed form analytical expressions, and test the PPCA on a set of charge distributions relevant to biomolecular modeling. We measure the accuracy of the new approximations as the RMS error in the electrostatic potential relative to that produced by the original charge distribution, at a distance 2x the extent of the charge distribution--the mid-field. The error for the 2-charge PPCA is found to be on average 23% smaller than that of optimally placed point dipole approximation, and comparable to that of the point quadrupole approximation. The standard deviation in RMS error for the 2-charge PPCA is 53% lower than that of the optimal point dipole approximation, and comparable to that of the point quadrupole approximation. We also calculate the 3-charge OPCA for representing the gas phase quantum mechanical charge distribution of a water molecule. The electrostatic potential calculated by the 3-charge OPCA for water, in the mid-field (2.8 Å from the oxygen atom, is on average 33.3% more accurate than the potential due to the point multipole expansion up to the octupole order. Compared to a 3 point charge approximation in which the charges are placed on the atom centers, the 3-charge OPCA is seven times more accurate, by RMS error. The maximum error at the oxygen-Na distance (2.23 Å is half that of the point multipole expansion up to the octupole
The symmetry group and harmonic potentials of an electrostatic generalized multipole
Institute of Scientific and Technical Information of China (English)
李钰
1995-01-01
The concept of an electrostatic ordinary multipole has been extended to an electrostatic generalized multipole which consists of a pair of close placed electrostatic ordinary multipole and electrostatic round lens. The definition of the M function for an electrostatic ordinary multipole has been extended to that of the M function for an electrostatic generalized multipole. The relation between the symmetry group of anelectrostaticordinary multipole and that of its corresponding electrostatic generalized multipole, and the relation between their constraint relations among their mth partial harmonic potentials have been derived. By analyzing some important electrostatic generalized multipoles, it is concluded that if an electrostatic deflector-multipole and an electrostatic round lens are placed close to each other , one cannot assert that this combined system can always be treated by the aberration theory of a combined focusing-deflection system.
Scalable fast multipole accelerated vortex methods
Hu, Qi
2014-05-01
The fast multipole method (FMM) is often used to accelerate the calculation of particle interactions in particle-based methods to simulate incompressible flows. To evaluate the most time-consuming kernels - the Biot-Savart equation and stretching term of the vorticity equation, we mathematically reformulated it so that only two Laplace scalar potentials are used instead of six. This automatically ensuring divergence-free far-field computation. Based on this formulation, we developed a new FMM-based vortex method on heterogeneous architectures, which distributed the work between multicore CPUs and GPUs to best utilize the hardware resources and achieve excellent scalability. The algorithm uses new data structures which can dynamically manage inter-node communication and load balance efficiently, with only a small parallel construction overhead. This algorithm can scale to large-sized clusters showing both strong and weak scalability. Careful error and timing trade-off analysis are also performed for the cutoff functions induced by the vortex particle method. Our implementation can perform one time step of the velocity+stretching calculation for one billion particles on 32 nodes in 55.9 seconds, which yields 49.12 Tflop/s.
Kaon photoproduction in a multipole approach
Mart, T
2006-01-01
The recently published experimental data on K+Lambda photoproduction by the SAPHIR, CLAS, and LEPS collaborations are analyzed by means of a multipole approach. For this purpose the background amplitudes are constructed from appropriate Feynman diagrams in a gauge-invariant and crossing-symmetric fashion. The results of our calculation emphasize the lack of mutual consistency between the SAPHIR and CLAS data previously found by several independent research groups, whereas the LEPS data are found to be more consistent with those of CLAS. The use of SAPHIR and CLAS data, individually or simultaneously, leads to quite different resonance parameters which, therefore, could lead to different conclusions on ``missing resonances''. Fitting to the SAPHIR and LEPS data simultaneously indicates that the S_{11}(1650), P_{13}(1720), D_{13}(1700), D_{13}(2080), F_{15}(1680), and F_{15}(2000) resonances are required, while fitting to the combination of CLAS and LEPS data leads alternatively to the P_{13}(1900), D_{13}(2080...
A new simple multidomain fast multipole boundary element method
Huang, S.; Liu, Y. J.
2016-09-01
A simple multidomain fast multipole boundary element method (BEM) for solving potential problems is presented in this paper, which can be applied to solve a true multidomain problem or a large-scale single domain problem using the domain decomposition technique. In this multidomain BEM, the coefficient matrix is formed simply by assembling the coefficient matrices of each subdomain and the interface conditions between subdomains without eliminating any unknown variables on the interfaces. Compared with other conventional multidomain BEM approaches, this new approach is more efficient with the fast multipole method, regardless how the subdomains are connected. Instead of solving the linear system of equations directly, the entire coefficient matrix is partitioned and decomposed using Schur complement in this new approach. Numerical results show that the new multidomain fast multipole BEM uses fewer iterations in most cases with the iterative equation solver and less CPU time than the traditional fast multipole BEM in solving large-scale BEM models. A large-scale fuel cell model with more than 6 million elements was solved successfully on a cluster within 3 h using the new multidomain fast multipole BEM.
Cardiac magnetic source imaging based on current multipole model
Institute of Scientific and Technical Information of China (English)
Tang Fa-Kuan; Wang Qian; Hua Ning; Lu Hong; Tang Xue-Zheng; Ma Ping
2011-01-01
It is widely accepted that the heart current source can be reduced into a current multipole. By adopting three linear inverse methods, the cardiac magnetic imaging is achieved in this article based on the current multipole model expanded to the first order terms. This magnetic imaging is realized in a reconstruction plane in the centre of human heart, where the current dipole array is employed to represent realistic cardiac current distribution. The current multipole as testing source generates magnetic fields in the measuring plane, serving as inputs of cardiac magnetic inverse problem. In the heart-torso model constructed by boundary element method, the current multipole magnetic field distribution is compared with that in the homogeneous infinite space, and also with the single current dipole magnetic field distribution.Then the minimum-norm least-squares (MNLS) method, the optimal weighted pseuDOInverse method (OWPIM), and the optimal constrained linear inverse method (OCLIM) are selected as the algorithms for inverse computation based on current multipole model innovatively, and the imaging effects of these three inverse methods are compared. Besides,two reconstructing parameters, residual and mean residual, are also discussed, and their trends under MNLS, OWPIM and OCLIM each as a function of SNR are obtained and compared.
Cumulative fatigue damage models
Mcgaw, Michael A.
1988-01-01
The problem of calculating expected component life under fatigue loading conditions is complicated by the fact that component loading histories contain, in many cases, cyclic loads of widely varying amplitudes. In such a case a cumulative damage model is required, in addition to a fatigue damage criterion, or life relationship, in order to compute the expected fatigue life. The traditional cumulative damage model used in design is the linear damage rule. This model, while being simple to use, can yield grossly unconservative results under certain loading conditions. Research at the NASA Lewis Research Center has led to the development of a nonlinear cumulative damage model, named the double damage curve approach (DDCA), that has greatly improved predictive capability. This model, which considers the life (or loading) level dependence of damage evolution, was applied successfully to two polycrystalline materials, 316 stainless steel and Haynes 188. The cumulative fatigue behavior of the PWA 1480 single-crystal material is currently being measured to determine the applicability of the DDCA for this material.
Michels, M.A.J.; Suttorp, L.G.
1972-01-01
The multipole expansion of the retarded interatomic dispersion energy is evaluated in the spherical-tensor formalism. The multipole expansion of the electrostatic dispersion energy follows as a special case.
A parallel fast multipole method for elliptic difference equations
Liska, Sebastian
2014-01-01
A new fast multipole formulation for solving elliptic PDEs on unbounded domains and its parallel implementation are presented. This method formally discretizes the PDE on an infinite Cartesian grid, and then solves the corresponding difference equations. In the analog to solving continuous inhomogeneous differential equations using Green's functions, the proposed method uses the fundamental solution of the discrete operator on an infinite grid, or lattice Green's function. Fast solutions O(N) are achieved by using a kernel-independent interpolation-based fast multipole method. Unlike other fast multipole algorithms, our approach exploits the regularity of the underlying Cartesian grid and the efficiency of FFTs to reduce the computation time. Our parallel implementation allows communications and computations to be overlapped and requires minimal global synchronization. The accuracy, efficiency, and parallel performance of the method are demonstrated through numerical experiments on the discrete 3D Poisson equ...
Advanced multipoles for accelerator magnets theoretical analysis and their measurement
Schnizer, Pierre
2017-01-01
This monograph presents research on the transversal beam dynamics of accelerators and evaluates and describes the respective magnetic field homogeneity. The widely used cylindrical circular multipoles have disadvantages for elliptical apertures or curved trajectories, and the book also introduces new types of advanced multipole magnets, detailing their application, as well as the numerical data and measurements obtained. The research presented here provides more precise descriptions of the field and better estimates of the beam dynamics. Moreover, the effects of field inhomogeneity can be estimated with higher precision than before. These findings are further elaborated to demonstrate their usefulness for real magnets and accelerator set ups, showing their advantages over cylindrical circular multipoles. The research findings are complemented with data obtained from the new superconducting beam guiding magnet models (SIS100) for the FAIR (Facility for Antiproton and Ion Research) project. Lastly, the book...
Gaussian translation operator for Multi-Level Fast Multipole Method
DEFF Research Database (Denmark)
Borries, Oscar Peter; Hansen, Per Christian; Sorensen, Stig B.
2014-01-01
Results using a new translation operator for the Multi-Level Fast Multipole Method are presented. Based on Gaussian beams, the translation operator allows a significant portion of the plane-wave directions to be neglected, resulting in a much faster translation step.......Results using a new translation operator for the Multi-Level Fast Multipole Method are presented. Based on Gaussian beams, the translation operator allows a significant portion of the plane-wave directions to be neglected, resulting in a much faster translation step....
Analysis of the diamagnetic effect in multipole Galatea traps
Bishaev, A. M.; Bugrova, A. I.; Gavrikov, M. B.; Kozintseva, M. V.; Lipatov, A. S.; Savel'ev, V. V.; Sigov, A. S.; Smirnov, P. G.; Tarelkin, I. A.; Khramtsov, P. P.
2013-04-01
The toroidal current emerging after the injection of a plasmoid through the magnetic shell of the Trimyx-3M (microwave) multipole trap is measured using the Rogowski loop. This current is due to diamagnetism of the plasma. The relation between the diamagnetic current and the maximal plasma pressure produced at the magnetic field separatrix is obtained. It is shown hence that magnetic measurements in a multi-pole trap for a known concentration make it possible to determine the plasma temperature in the trap and the energy confinement time.
Spiralling solitons and multipole localized modes in nonlocal nonlinear media
DEFF Research Database (Denmark)
Buccoliero, Daniel; Lopez-Aguayo, Servando; Skupin, Stefan
2007-01-01
We analyze the propagation of rotating multi-soliton localized structures in optical media with spatially nonlocal nonlinearity. We demonstrate that nonlocality stabilizes the azimuthal breakup of rotating dipole as well as multipole localized soliton modes. We compare the results for two differe...... models of nonlocal nonlinearity and suggest that the stabilization mechanism is a generic property of a spatial nonlocal nonlinear response independent of its particular functional form.......We analyze the propagation of rotating multi-soliton localized structures in optical media with spatially nonlocal nonlinearity. We demonstrate that nonlocality stabilizes the azimuthal breakup of rotating dipole as well as multipole localized soliton modes. We compare the results for two different...
Performance Benchmarking of Fast Multipole Methods
Al-Harthi, Noha A.
2013-06-01
The current trends in computer architecture are shifting towards smaller byte/flop ratios, while available parallelism is increasing at all levels of granularity – vector length, core count, and MPI process. Intel’s Xeon Phi coprocessor, NVIDIA’s Kepler GPU, and IBM’s BlueGene/Q all have a Byte/flop ratio close to 0.2, which makes it very difficult for most algorithms to extract a high percentage of the theoretical peak flop/s from these architectures. Popular algorithms in scientific computing such as FFT are continuously evolving to keep up with this trend in hardware. In the meantime it is also necessary to invest in novel algorithms that are more suitable for computer architectures of the future. The fast multipole method (FMM) was originally developed as a fast algorithm for ap- proximating the N-body interactions that appear in astrophysics, molecular dynamics, and vortex based fluid dynamics simulations. The FMM possesses have a unique combination of being an efficient O(N) algorithm, while having an operational intensity that is higher than a matrix-matrix multiplication. In fact, the FMM can reduce the requirement of Byte/flop to around 0.01, which means that it will remain compute bound until 2020 even if the cur- rent trend in microprocessors continues. Despite these advantages, there have not been any benchmarks of FMM codes on modern architectures such as Xeon Phi, Kepler, and Blue- Gene/Q. This study aims to provide a comprehensive benchmark of a state of the art FMM code “exaFMM” on the latest architectures, in hopes of providing a useful reference for deciding when the FMM will become useful as the computational engine in a given application code. It may also serve as a warning to certain problem size domains areas where the FMM will exhibit insignificant performance improvements. Such issues depend strongly on the asymptotic constants rather than the asymptotics themselves, and therefore are strongly implementation and hardware
Exchange splitting of the interaction energy and the multipole expansion of the wave function
Gniewek, Piotr
2015-01-01
The exchange splitting $J$ of the interaction energy of the hydrogen atom with a proton is calculated using the conventional surface-integral formula $J_{\\textrm{surf}}[\\varphi]$, the volume-integral formula of the symmetry-adapted perturbation theory $J_{\\textrm{SAPT}}[\\varphi]$, and a variational volume-integral formula $J_{\\textrm{var}}[\\varphi]$. The calculations are based on the multipole expansion of the wave function $\\varphi$, which is divergent for any internuclear distance $R$. Nevertheless, the resulting approximations to the leading coefficient $j_0$ in the large-$R$ asymptotic series $J(R) = 2 e^{-R-1} R ( j_0 + j_1 R^{-1} + j_2 R^{-2} +\\cdots ) $ converge, with the rate corresponding to the convergence radii equal to 4, 2, and 1 when the $J_{\\textrm{var}}[\\varphi]$, $J_{\\textrm{surf}}[\\varphi]$, and $J_{\\textrm{SAPT}}[\\varphi]$ formulas are used, respectively. Additionally, we observe that also the higher $j_k$ coefficients are predicted correctly when the multipole expansion is used in the $J_{...
Werner, Hans-Joachim
2016-11-01
The accuracy of multipole approximations for distant pair energies in local second-order Møller-Plesset perturbation theory (LMP2) as introduced by Hetzer et al. [Chem. Phys. Lett. 290, 143 (1998)] is investigated for three chemical reactions involving molecules with up to 92 atoms. Various iterative and non-iterative approaches are compared, using different energy thresholds for distant pair selection. It is demonstrated that the simple non-iterative dipole-dipole approximation, which has been used in several recent pair natural orbitals (PNO)-LMP2 and PNO-LCCSD (local coupled-cluster with singles and doubles) methods, may underestimate the distant pair energies by up to 50% and can lead to significant errors in relative energies, unless very tight thresholds are used. The accuracy can be much improved by including higher multipole orders and by optimizing the distant pair amplitudes iteratively along with all other amplitudes. A new approach is presented in which very small special PNO domains for distant pairs are used in the iterative approach. This reduces the number of distant pair amplitudes by 3 orders of magnitude and keeps the additional computational effort for the iterative optimization of distant pair amplitudes minimal.
Multilevel Fast Multipole Method for Higher Order Discretizations
DEFF Research Database (Denmark)
Borries, Oscar Peter; Meincke, Peter; Jorgensen, Erik;
2014-01-01
The multi-level fast multipole method (MLFMM) for a higher order (HO) discretization is demonstrated on high-frequency (HF) problems, illustrating for the first time how an efficient MLFMM for HO can be achieved even for very large groups. Applying several novel ideas, beneficial to both lower or...
Two-center-multipole expansion method: application to macromolecular systems
DEFF Research Database (Denmark)
Solov'yov, Ilia; Yakubovich, Alexander V.; Solov'yov, Andrey V.;
2007-01-01
We propose a theoretical method for the calculation of the interaction energy between macromolecular systems at large distances. The method provides a linear scaling of the computing time with the system size and is considered as an alternative to the well-known fast multipole method. Its...
Concept of multipole magnetic ﬁeld rotation in ECRIS
Indian Academy of Sciences (India)
M H Rashid; R K Bhandari
2002-11-01
The conventional type of magnetic well is formed by superposition of two types of magnetic ﬁeld, axial bumpy ﬁeld and radial multipole ﬁeld. It is used to contain plasma that consists of neutrals, ions and electrons. These particles are in constant motion in the well and energetic electrons create plasma by violent collisions with neutrals and ions. The conﬁned electrons are constantly heated by ECR technique in the presence of magnetic ﬁeld. In this paper it has been shown theoretically that how the electron motion is inﬂuenced in terms of heating, containment and azimuthal uniformity of plasma, by the axial rotation of the multipole magnetic ﬁeld [1,2]. Afterwards, the feasibility of achieving a rotating magnetic multipole ﬁeld is discussed to some extent. And it is seen that it is not beyond the capability of the scientiﬁc community in the present scenario of the advanced technology. Presently, it can be achieved for lesser ﬁeld and slightly larger size of the multipole electromagnet and can be used for improvement of the ECR ion source (ECRIS).
Improved Multilevel Fast Multipole Method for Higher-Order discretizations
DEFF Research Database (Denmark)
Borries, Oscar Peter; Meincke, Peter; Jorgensen, Erik
2014-01-01
The Multilevel Fast Multipole Method (MLFMM) allows for a reduced computational complexity when solving electromagnetic scattering problems. Combining this with the reduced number of unknowns provided by Higher-Order discretizations has proven to be a difficult task, with the general conclusion b...
Cumulative Timers for Microprocessors
Battle, John O.
2007-01-01
It has been proposed to equip future microprocessors with electronic cumulative timers, for essentially the same reasons for which land vehicles are equipped with odometers (total-distance-traveled meters) and aircraft are equipped with Hobbs meters (total-engine-operating time meters). Heretofore, there has been no way to determine the amount of use to which a microprocessor (or a product containing a microprocessor) has been subjected. The proposed timers would count all microprocessor clock cycles and could only be read by means of microprocessor instructions but, like odometers and Hobbs meters, could never be reset to zero without physically damaging the chip.
Cumulative Vehicle Routing Problems
Kara, &#;mdat; Kara, Bahar Yeti&#;; Yeti&#;, M. Kadri
2008-01-01
This paper proposes a new objective function and corresponding formulations for the vehicle routing problem. The new cost function defined as the product of the distance of the arc and the flow on that arc. We call a vehicle routing problem with this new objective function as the Cumulative Vehicle Routing Problem (CumVRP). Integer programming formulations with O(n2) binary variables and O(n2) constraints are developed for both collection and delivery cases. We show that the CumVRP is a gener...
Price, Sarah L; Leslie, Maurice; Welch, Gareth W A; Habgood, Matthew; Price, Louise S; Karamertzanis, Panagiotis G; Day, Graeme M
2010-08-14
Crystal structure prediction for organic molecules requires both the fast assessment of thousands to millions of crystal structures and the greatest possible accuracy in their relative energies. We describe a crystal lattice simulation program, DMACRYS, emphasizing the features that make it suitable for use in crystal structure prediction for pharmaceutical molecules using accurate anisotropic atom-atom model intermolecular potentials based on the theory of intermolecular forces. DMACRYS can optimize the lattice energy of a crystal, calculate the second derivative properties, and reduce the symmetry of the spacegroup to move away from a transition state. The calculated terahertz frequency k = 0 rigid-body lattice modes and elastic tensor can be used to estimate free energies. The program uses a distributed multipole electrostatic model (Q, t = 00,...,44s) for the electrostatic fields, and can use anisotropic atom-atom repulsion models, damped isotropic dispersion up to R(-10), as well as a range of empirically fitted isotropic exp-6 atom-atom models with different definitions of atomic types. A new feature is that an accurate model for the induction energy contribution to the lattice energy has been implemented that uses atomic anisotropic dipole polarizability models (alpha, t = (10,10)...(11c,11s)) to evaluate the changes in the molecular charge density induced by the electrostatic field within the crystal. It is demonstrated, using the four polymorphs of the pharmaceutical carbamazepine C(15)H(12)N(2)O, that whilst reproducing crystal structures is relatively easy, calculating the polymorphic energy differences to the accuracy of a few kJ mol(-1) required for applications is very demanding of assumptions made in the modelling. Thus DMACRYS enables the comparison of both known and hypothetical crystal structures as an aid to the development of pharmaceuticals and other speciality organic materials, and provides a tool to develop the modelling of the
Pillet, S; Souhassou, M; Lecomte, C; Schwarz, K; Blaha, P; Rérat, M; Lichanot, A; Roversi, P
2001-05-01
This electron-density study on corundum (alpha-Al2O3) is part of the Multipole Refinement Project supported by the IUCr Commission on Charge, Spin and Momentum Densities. For this purpose, eight different data sets (two experimental and six theoretical) were chosen from which the electron density was derived by multipolar refinement (using the MOLLY program). The two experimental data sets were collected on a conventional CAD4 and at ESRF, ID11 with a CCD detector, respectively. The theoretical data sets consist of static, dynamic, static noisy and dynamic noisy moduli of structure factors calculated at the Hartree-Fock (HF) and density functional theory (DFT) levels. Comparisons of deformation and residual densities show that the multipolar analysis works satisfactorily but also indicate some drawbacks in the refinement. Some solutions and improvements during the refinements are proposed like contraction or expansion of the inner atomic shells or increasing the order of the spherical harmonic expansion.
Lorenzen, Konstantin; Mathias, Gerald; Tavan, Paul
2015-11-14
Hamiltonian Dielectric Solvent (HADES) is a recent method [S. Bauer et al., J. Chem. Phys. 140, 104103 (2014)] which enables atomistic Hamiltonian molecular dynamics (MD) simulations of peptides and proteins in dielectric solvent continua. Such simulations become rapidly impractical for large proteins, because the computational effort of HADES scales quadratically with the number N of atoms. If one tries to achieve linear scaling by applying a fast multipole method (FMM) to the computation of the HADES electrostatics, the Hamiltonian character (conservation of total energy, linear, and angular momenta) may get lost. Here, we show that the Hamiltonian character of HADES can be almost completely preserved, if the structure-adapted fast multipole method (SAMM) as recently redesigned by Lorenzen et al. [J. Chem. Theory Comput. 10, 3244-3259 (2014)] is suitably extended and is chosen as the FMM module. By this extension, the HADES/SAMM forces become exact gradients of the HADES/SAMM energy. Their translational and rotational invariance then guarantees (within the limits of numerical accuracy) the exact conservation of the linear and angular momenta. Also, the total energy is essentially conserved-up to residual algorithmic noise, which is caused by the periodically repeated SAMM interaction list updates. These updates entail very small temporal discontinuities of the force description, because the employed SAMM approximations represent deliberately balanced compromises between accuracy and efficiency. The energy-gradient corrected version of SAMM can also be applied, of course, to MD simulations of all-atom solvent-solute systems enclosed by periodic boundary conditions. However, as we demonstrate in passing, this choice does not offer any serious advantages.
Energy Technology Data Exchange (ETDEWEB)
Lorenzen, Konstantin; Mathias, Gerald; Tavan, Paul, E-mail: tavan@physik.uni-muenchen.de [Lehrstuhl für BioMolekulare Optik, Ludig–Maximilians Universität München, Oettingenstr. 67, 80538 München (Germany)
2015-11-14
Hamiltonian Dielectric Solvent (HADES) is a recent method [S. Bauer et al., J. Chem. Phys. 140, 104103 (2014)] which enables atomistic Hamiltonian molecular dynamics (MD) simulations of peptides and proteins in dielectric solvent continua. Such simulations become rapidly impractical for large proteins, because the computational effort of HADES scales quadratically with the number N of atoms. If one tries to achieve linear scaling by applying a fast multipole method (FMM) to the computation of the HADES electrostatics, the Hamiltonian character (conservation of total energy, linear, and angular momenta) may get lost. Here, we show that the Hamiltonian character of HADES can be almost completely preserved, if the structure-adapted fast multipole method (SAMM) as recently redesigned by Lorenzen et al. [J. Chem. Theory Comput. 10, 3244-3259 (2014)] is suitably extended and is chosen as the FMM module. By this extension, the HADES/SAMM forces become exact gradients of the HADES/SAMM energy. Their translational and rotational invariance then guarantees (within the limits of numerical accuracy) the exact conservation of the linear and angular momenta. Also, the total energy is essentially conserved—up to residual algorithmic noise, which is caused by the periodically repeated SAMM interaction list updates. These updates entail very small temporal discontinuities of the force description, because the employed SAMM approximations represent deliberately balanced compromises between accuracy and efficiency. The energy-gradient corrected version of SAMM can also be applied, of course, to MD simulations of all-atom solvent-solute systems enclosed by periodic boundary conditions. However, as we demonstrate in passing, this choice does not offer any serious advantages.
Indian Academy of Sciences (India)
R Saravanan; K S Syed Ali; S Israel
2008-04-01
The local, average and electronic structure of the semiconducting materials Si and Ge has been studied using multipole, maximum entropy method (MEM) and pair distribution function (PDF) analyses, using X-ray powder data. The covalent nature of bonding and the interaction between the atoms are clearly revealed by the two-dimensional MEM maps plotted on (1 0 0) and (1 1 0) planes and one-dimensional density along [1 0 0], [1 1 0] and [1 1 1] directions. The mid-bond electron densities between the atoms are 0.554 e/Å3 and 0.187 e/Å3 for Si and Ge respectively. In this work, the local structural information has also been obtained by analyzing the atomic pair distribution function. An attempt has been made in the present work to utilize the X-ray powder data sets to refine the structure and electron density distribution using the currently available versatile methods, MEM, multipole analysis and determination of pair distribution function for these two systems.
Cumulative environmental effects. Summary
Energy Technology Data Exchange (ETDEWEB)
NONE
2012-07-01
This report presents a compilation of knowledge about the state of the environment and human activity in the Norwegian part of the North Sea and Skagerrak. The report gives an overview of pressures and impacts on the environment from normal activity and in the event of accidents. This is used to assess the cumulative environmental effects, which factors have most impact and where the impacts are greatest, and to indicate which problems are expected to be most serious in the future. The report is intended to provide relevant information that can be used in the management of the marine area in the future. It also provides input for the identification of environmental targets and management measures for the North Sea and Skagerrak.(Author)
Optical theorem for multipole sources in wave diffraction theory
Eremin, Yu. A.; Sveshnikov, A. G.
2016-05-01
The optical theorem is generalized to the case of local body excitation by multipole sources. It is found that, to calculate the extinction cross section, it is sufficient to calculate the scattered field derivatives at a single point. It is shown that the Purcell factor, which is a rather important parameter, can be represented in analytic form. The result is generalized to the case of a local scatterer incorporated in a homogeneous halfspace.
PROGRAM-PATTERN MULTIPOLE BOUNDARY ELEMENT METHOD FOR FRICTIONAL CONTACT
Institute of Scientific and Technical Information of China (English)
Yu Chunxiao; Shen Guangxian; Liu Deyi
2005-01-01
A mathematical program is proposed for the highly nonlinear problem involving frictional contact. A program-pattern using the fast multipole boundary element method (FMBEM) is given for 3-D elastic contact with friction to replace the Monte Carlo method. A new optimized generalized minimal residual (GMRES) algorithm is presented. Numerical examples demonstrate the validity of the program-pattern optimization model for node-to-surface contact with friction. The GMRES algorithm greatly improves the computational efficiency.
Mathematical Programming Solution for the Frictional Contact Multipole BEM
Institute of Scientific and Technical Information of China (English)
YU Chunxiao; SHEN Guangxian; LIU Deyi
2005-01-01
This paper presents a new mathematical model for the highly nonlinear problem of frictional contact. A programming model, multipole boundary element method (BEM), was developed for 3-D elastic contact with friction to replace the Monte Carlo method. A numerical example shows that the optimization programming model for the point-to-surface contact with friction and the fast optimization generalized minimal residual algorithm (GMRES(m)) significantly improve the analysis of such problems relative to the conventional BEM.
A single-site multipole model for liquid water
Tran, Kelly N.; Tan, Ming-Liang; Ichiye, Toshiko
2016-07-01
Accurate and efficient empirical potential energy models that describe the atomistic interactions between water molecules in the liquid phase are essential for computer simulations of many problems in physics, chemistry, and biology, especially when long length or time scales are important. However, while models with non-polarizable partial charges at four or five sites in a water molecule give remarkably good values for certain properties, deficiencies have been noted in other properties and increasing the number of sites decreases computational efficiency. An alternate approach is to utilize a multipole expansion of the electrostatic potential due to the molecular charge distribution, which is exact outside the charge distribution in the limits of infinite distances or infinite orders of multipoles while partial charges are a qualitative representation of electron density as point charges. Here, a single-site multipole model of water is presented, which is as fast computationally as three-site models but is also more accurate than four- and five-site models. The dipole, quadrupole, and octupole moments are from quantum mechanical-molecular mechanical calculations so that they account for the average polarization in the liquid phase, and represent both the in-plane and out-of-plane electrostatic potentials of a water molecule in the liquid phase. This model gives accurate thermodynamic, dynamic, and dielectric properties at 298 K and 1 atm, as well as good temperature and pressure dependence of these properties.
Development of a multi-pole magnetorheological brake
Shiao, Yaojung; Nguyen, Quang-Anh
2013-06-01
This paper presents a new approach in the design and optimization of a novel multi-pole magnetorheological (MR) brake that employs magnetic flux more effectively on the surface of the rotor. MR brakes with conventional single ring-type electromagnetic poles have reached the limits of torque enhancement. One major reason is the limitation of the magnetic field strength within the active area of the MR fluid due to the geometric constraints of the coil. The multi-pole MR brake design features multiple electromagnetic poles surrounded by several coils. As a result, the active chaining areas for the MR fluid are greatly increased, and significant brake torque improvement is achieved. The coil structure, as a part of the stator, becomes flexible and customizable in terms of space usage for the winding and bobbin design. In addition, this brake offers extra options in its dimensions for torque enhancement because either the radial or the axial dimensions of the rotor can be increased. Magnetic circuit analysis was conducted to analyze the effects of the design parameters on the field torque. After that, simulations were done to find the optimal design under all major geometric constraints with a given power supply. The results show that the multi-pole MR brake provides a considerable braking torque increase while maintaining a compact and solid design. This is confirmation of its feasibility in actual braking applications.
Petascale molecular dynamics simulation using the fast multipole method on K computer
Ohno, Yousuke
2014-10-01
In this paper, we report all-atom simulations of molecular crowding - a result from the full node simulation on the "K computer", which is a 10-PFLOPS supercomputer in Japan. The capability of this machine enables us to perform simulation of crowded cellular environments, which are more realistic compared to conventional MD simulations where proteins are simulated in isolation. Living cells are "crowded" because macromolecules comprise ∼30% of their molecular weight. Recently, the effects of crowded cellular environments on protein stability have been revealed through in-cell NMR spectroscopy. To measure the performance of the "K computer", we performed all-atom classical molecular dynamics simulations of two systems: target proteins in a solvent, and target proteins in an environment of molecular crowders that mimic the conditions of a living cell. Using the full system, we achieved 4.4 PFLOPS during a 520 million-atom simulation with cutoff of 28 Å. Furthermore, we discuss the performance and scaling of fast multipole methods for molecular dynamics simulations on the "K computer", as well as comparisons with Ewald summation methods. © 2014 Elsevier B.V. All rights reserved.
Cluster-Based Multipolling Sequencing Algorithm for Collecting RFID Data in Wireless LANs
Choi, Woo-Yong; Chatterjee, Mainak
2015-03-01
With the growing use of RFID (Radio Frequency Identification), it is becoming important to devise ways to read RFID tags in real time. Access points (APs) of IEEE 802.11-based wireless Local Area Networks (LANs) are being integrated with RFID networks that can efficiently collect real-time RFID data. Several schemes, such as multipolling methods based on the dynamic search algorithm and random sequencing, have been proposed. However, as the number of RFID readers associated with an AP increases, it becomes difficult for the dynamic search algorithm to derive the multipolling sequence in real time. Though multipolling methods can eliminate the polling overhead, we still need to enhance the performance of the multipolling methods based on random sequencing. To that extent, we propose a real-time cluster-based multipolling sequencing algorithm that drastically eliminates more than 90% of the polling overhead, particularly so when the dynamic search algorithm fails to derive the multipolling sequence in real time.
UBIQUITOUS POLLUTANTS FROM CUMULATIVE ...
The occurrence of pharmaceuticals and personal care products (PPCPS) as environmental pollutants is a multifaceted issue whose scope continues to become better delineated since the escalation of concerted attention beginning in the 1980s. PPCPs typically occur as trace environmental pollutants (primarily in surface but also in ground waters) as a result of their widespread, continuous, combined usage in a broad range of human and veterinary therapeutic activities and practices. With respect to the risk-assessment paradigm, the growing body of published work has focused primarily on the origin and occurrence of these substances. Comparatively less is known about human and ecological exposure, and even less about the known or even potential hazards associated with exposure to these anthropogenic substances, many of which are highly bioactive. The continually growing, worldwide importance of freshwater resources underscores the need for ensuring that any aggregate or cumulative impacts on water supplies and resultant potential for human or ecological exposure be minimized. This has prompted the more recent investigations on waste treatment processes for one of the major sources of environmental disposition, namely sewage. Despite the paucity of health effects data for long-term, simultaneous exposure to multiple xenobiotics (particularly PPCPS) at low doses (a major toxicological issue that can be described by the
Multipole interference in the second-harmonic optical radiation from gold nanoparticles.
Kujala, Sami; Canfield, Brian K; Kauranen, Martti; Svirko, Yuri; Turunen, Jari
2007-04-20
We provide experimental evidence of higher multipole (magnetic dipole and electric quadrupole) radiation in second-harmonic (SH) generation from arrays of metal nanoparticles. Fundamental differences in the radiative properties of electric dipoles and higher multipoles yield opposite interference effects observed in the SH intensities measured in the reflected and transmitted directions. These interference effects clearly depend on the polarization of the fundamental field, directly indicating the importance of multipole effects in the nonlinear response. We estimate that higher multipoles contribute up to 20% of the total emitted SH field amplitude for certain polarization configurations.
Hickstein, Daniel D.; Cole, Jacqueline M.; Turner, Michael J.; Jayatilaka, Dylan
2013-08-01
The rational design of next-generation optical materials requires an understanding of the connection between molecular structure and the solid-state optical properties of a material. A fundamental challenge is to utilize the accurate structural information provided by X-ray diffraction to explain the properties of a crystal. For years, the multipole refinement has been the workhorse technique for transforming high-resolution X-ray diffraction datasets into the detailed electron density distribution of crystalline material. However, the electron density alone is not sufficient for a reliable calculation of the nonlinear optical properties of a material. Recently, the X-ray constrained wavefunction refinement has emerged as a viable alternative to the multipole refinement, offering several potential advantages, including the calculation of a wide range of physical properties and seeding the refinement process with a physically reasonable starting point. In this study, we apply both the multipole refinement and the X-ray constrained wavefunction technique to four molecules with promising nonlinear optical properties and diverse structural motifs. In general, both techniques obtain comparable figures of merit and generate largely similar electron densities, demonstrating the wide applicability of the X-ray constrained wavefunction method. However, there are some systematic differences between the electron densities generated by each technique. Importantly, we find that the electron density generated using the X-ray constrained wavefunction method is dependent on the exact location of the nuclei. The X-ray constrained wavefunction refinement makes smaller changes to the wavefunction when coordinates from the Hartree-Fock-based Hirshfeld atom refinement are employed rather than coordinates from the multipole refinement, suggesting that coordinates from the Hirshfeld atom refinement allow the X-ray constrained wavefunction method to produce more accurate wavefunctions. We
Bereau, Tristan
2014-01-01
We estimate polarizabilities of atoms in molecules without electron density, using a Voronoi partitioning approach instead. The resulting atomic dispersion coefficients are calculated, as well as many-body dispersion effects on intermolecular potential energies. We also estimate contributions from multipole electrostatics and compare them to dispersion. We assess the performance of the resulting intermolecular potential from dispersion and electrostatics for more than 1,300 neutral and charged, small organic molecular dimers. Applications to water clusters, the benzene crystal, the anti-cancer drug ellipticine---intercalated between two Watson-Crick DNA base pairs, as well as six macro-molecular host-guest complexes highlight the potential of this method and help to identify points of future improvement. Overall, the method achieves an accuracy well within sophisticated empirical force fields, such as OPLS and Amber FF03, while exhibiting a simple parametrization protocol without the need for experimental inp...
Multipole expansions in the representation of current sources.
Trontelj, Z; Jazbinsek, V; Erné, S N; Trahms, L
1991-01-01
After obtaining the measured magnetic field or its components in the form of an isofield map one has to decide which approximation to use in solving the inverse problem. A single current dipole as an equivalent current source is often used. It will be shown when this approximation fails and one possible way to improve the equivalent source description. The expansion of current multipoles is discussed up to the second order. The localization of an equivalent current source in this case is considered. The application of this type of expansion is analysed and discussed.
Experimental demonstration of a surface-electrode multipole ion trap
Maurice, Mark; Green, Dylan; Farr, Andrew; Burke, Timothy; Hilleke, Russell; Clark, Robert
2015-01-01
We report on the design and experimental characterization of a surface-electrode multipole ion trap. Individual microscopic sugar particles are confined in the trap. The trajectories of driven particle motion are compared with a theoretical model, both to verify qualitative predictions of the model, and to measure the charge-to-mass ratio of the confined particle. The generation of harmonics of the driving frequency is observed as a key signature of the nonlinear nature of the trap. We remark on possible applications of our traps, including to mass spectrometry.
Analytical expressions for fringe fields in multipole magnets
Directory of Open Access Journals (Sweden)
B. D. Muratori
2015-06-01
Full Text Available Fringe fields in multipole magnets can have a variety of effects on the linear and nonlinear dynamics of particles moving along an accelerator beam line. An accurate model of an accelerator must include realistic models of the magnet fringe fields. Fringe fields for dipoles are well understood and can be modeled at an early stage of accelerator design in such codes as mad8, madx, gpt or elegant. Existing techniques for quadrupole and higher order multipoles rely either on the use of a numerical field map, or on a description of the field in the form of a series expansion about a chosen axis. Usually, it is not until the later stages of a design project that such descriptions (based on magnet modeling or measurement become available. Furthermore, series expansions rely on the assumption that the beam travels more or less on axis throughout the beam line; but in some types of machines (for example, Fixed Field Alternating Gradients or FFAGs this is not a good assumption. Furthermore, some tracking codes, such as gpt, use methods for including space charge effects that require fields to vary smoothly and continuously along a beam line: in such cases, realistic fringe field models are of significant importance. In this paper, a method for constructing analytical expressions for multipole fringe fields is presented. Such expressions allow fringe field effects to be included in beam dynamics simulations from the start of an accelerator design project, even before detailed magnet design work has been undertaken. The magnetostatic Maxwell equations are solved analytically and a solution that fits all orders of multipoles is derived. Quadrupole fringe fields are considered in detail as these are the ones that give the strongest effects. The analytic expressions for quadrupole fringe fields are compared with data obtained from numerical modeling codes in two cases: a magnet in the high luminosity upgrade of the Large Hadron Collider inner triplet, and a
Multipole shimming of permanent magnets using harmonic corrector rings.
Jachmann, R C; Trease, D R; Bouchard, L-S; Sakellariou, D; Martin, R W; Schlueter, R D; Budinger, T F; Pines, A
2007-03-01
Shimming systems are required to provide sufficient field homogeneity for high resolution nuclear magnetic resonance (NMR). In certain specialized applications, such as rotating-field NMR and mobile ex situ NMR, permanent magnet-based shimming systems can provide considerable advantages. We present a simple two-dimensional shimming method based on harmonic corrector rings which can provide arbitrary multipole order shimming corrections. Results demonstrate, for example, that quadrupolar order shimming improves the linewidth by up to an order of magnitude. An additional order of magnitude reduction is in principle achievable by utilizing this shimming method for z-gradient correction and higher order xy gradients.
New Multipole Method for 3-D Capacitance Extraction
Institute of Scientific and Technical Information of China (English)
Zhao-Zhi Yang; Ze-Yi Wang
2004-01-01
This paper describes an effcient improvement of the multipole accelerated boundary element method for 3-D capacitance extraction.The overall relations between the positions of 2-D boundary elements are considered instead of only the relations between the center-points of the elements,and a new method of cube partitioning is introduced.Numerical results are presented to demonstrate that the method is accurate and has nearly linear computational growth as O(n),where n is the number of panels/boundary elements.The proposed method is more accurate and much faster than Fastcap.
Magnetostatic solution by hybrid technique and fast multipole method
Energy Technology Data Exchange (ETDEWEB)
Gruosso, G. [Politecnico di Milano, Dipartimento di Elettronica e Informazione, I-20133 Milan (Italy); Repetto, M. [Politecnico di Torino, Dipartimento di Ingegneria Elettrica, C.so Duca Abruzzi 24, I-10129 Turin (Italy)], E-mail: maurizio.repetto@polito.it
2008-02-01
The use of fast multipole method (FMM) in the solution of a magnetostatic problem is presented. The magnetostatic solution strategy is based on finite formulation of electromagnetic field coupled with an integral formulation for the definition of boundary conditions on the external surface of the unstructured mesh. Due to the hypothesis of micromagnetic problem, the resulting matrix structure is sparse and integral terms are only on the RHS. Magnetic surface charge is used as source of these integral terms and is localized on the faces between tetrahedra. The computation of the integral terms can be performed by analytical formulas for the near field contributes and by FMM for far field ones.
Multipole Expansions of Aggregate Charge: How Far to Go?
Matthews, Lorin S; Hyde, Truell W
2015-01-01
Aggregates immersed in a plasma or radiative environment will have charge distributed over their extended surface. Previous studies have modeled the aggregate charge using the monopole and dipole terms of a multipole expansion, with results indicating that the dipole-dipole interactions play an important role in increasing the aggregation rate and altering the morphology of the resultant aggregates. This study examines the effect that including the quadrupole terms has on the dynamics of aggregates interacting with each other and the confining electric fields in laboratory experiments. Results are compared to modeling aggregates as a collection of point charges located at the center of each spherical monomer comprising the aggregate.
Multipole approach for photo- and electroproduction of kaon
Mart, T
2007-01-01
We have analyzed the experimental data on K+Lambda photoproduction by using a multipole approach. In this analysis we use the background amplitudes constructed from appropriate Feynman diagrams in a gauge-invariant and crossing-symmetric fashion. Results of our analysis reveal the problem of mutual consistency between the new SAPHIR and CLAS data. We found that the problem could lead to different conclusions on ``missing resonances''. We have also extended our analysis to the finite Q^2 region and compared the result with the corresponding electroproduction data.
Atomic Structure Theory Lectures on Atomic Physics
Johnson, Walter R
2007-01-01
Atomic Structure Theory is a textbook for students with a background in quantum mechanics. The text is designed to give hands-on experience with atomic structure calculations. Material covered includes angular momentum methods, the central field Schrödinger and Dirac equations, Hartree-Fock and Dirac-Hartree-Fock equations, multiplet structure, hyperfine structure, the isotope shift, dipole and multipole transitions, basic many-body perturbation theory, configuration interaction, and correlation corrections to matrix elements. Numerical methods for solving the Schrödinger and Dirac eigenvalue problems and the (Dirac)-Hartree-Fock equations are given as well. B-spline basis sets are used to carry out sums arising in higher-order many-body calculations. Illustrative problems are provided, together with solutions. FORTRAN programs implementing the numerical methods in the text are included.
Directory of Open Access Journals (Sweden)
Daniel J Kuster
Full Text Available Theoretical and experimental evidence for non-linear hydrogen bonds in protein helices is ubiquitous. In particular, amide three-centered hydrogen bonds are common features of helices in high-resolution crystal structures of proteins. These high-resolution structures (1.0 to 1.5 Å nominal crystallographic resolution position backbone atoms without significant bias from modeling constraints and identify Φ = -62°, ψ = -43 as the consensus backbone torsional angles of protein helices. These torsional angles preserve the atomic positions of α-β carbons of the classic Pauling α-helix while allowing the amide carbonyls to form bifurcated hydrogen bonds as first suggested by Némethy et al. in 1967. Molecular dynamics simulations of a capped 12-residue oligoalanine in water with AMOEBA (Atomic Multipole Optimized Energetics for Biomolecular Applications, a second-generation force field that includes multipole electrostatics and polarizability, reproduces the experimentally observed high-resolution helical conformation and correctly reorients the amide-bond carbonyls into bifurcated hydrogen bonds. This simple modification of backbone torsional angles reconciles experimental and theoretical views to provide a unified view of amide three-centered hydrogen bonds as crucial components of protein helices. The reason why they have been overlooked by structural biologists depends on the small crankshaft-like changes in orientation of the amide bond that allows maintenance of the overall helical parameters (helix pitch (p and residues per turn (n. The Pauling 3.6(13 α-helix fits the high-resolution experimental data with the minor exception of the amide-carbonyl electron density, but the previously associated backbone torsional angles (Φ, Ψ needed slight modification to be reconciled with three-atom centered H-bonds and multipole electrostatics. Thus, a new standard helix, the 3.6(13/10-, Némethy- or N-helix, is proposed. Due to the use of
Kuster, Daniel J; Liu, Chengyu; Fang, Zheng; Ponder, Jay W; Marshall, Garland R
2015-01-01
Theoretical and experimental evidence for non-linear hydrogen bonds in protein helices is ubiquitous. In particular, amide three-centered hydrogen bonds are common features of helices in high-resolution crystal structures of proteins. These high-resolution structures (1.0 to 1.5 Å nominal crystallographic resolution) position backbone atoms without significant bias from modeling constraints and identify Φ = -62°, ψ = -43 as the consensus backbone torsional angles of protein helices. These torsional angles preserve the atomic positions of α-β carbons of the classic Pauling α-helix while allowing the amide carbonyls to form bifurcated hydrogen bonds as first suggested by Némethy et al. in 1967. Molecular dynamics simulations of a capped 12-residue oligoalanine in water with AMOEBA (Atomic Multipole Optimized Energetics for Biomolecular Applications), a second-generation force field that includes multipole electrostatics and polarizability, reproduces the experimentally observed high-resolution helical conformation and correctly reorients the amide-bond carbonyls into bifurcated hydrogen bonds. This simple modification of backbone torsional angles reconciles experimental and theoretical views to provide a unified view of amide three-centered hydrogen bonds as crucial components of protein helices. The reason why they have been overlooked by structural biologists depends on the small crankshaft-like changes in orientation of the amide bond that allows maintenance of the overall helical parameters (helix pitch (p) and residues per turn (n)). The Pauling 3.6(13) α-helix fits the high-resolution experimental data with the minor exception of the amide-carbonyl electron density, but the previously associated backbone torsional angles (Φ, Ψ) needed slight modification to be reconciled with three-atom centered H-bonds and multipole electrostatics. Thus, a new standard helix, the 3.6(13/10)-, Némethy- or N-helix, is proposed. Due to the use of constraints from
Higher Electric Multipole Moments for Some Polyatomic Molecules from Accurate SCF Calculations
Institute of Scientific and Technical Information of China (English)
Telhat Ozdogan
2002-01-01
Higher electric multipole moments for the ground-state electronic configuration of some polyatomicmolecules, i.e. CH4, NH3, H2O, were calculated from SCF-HFR wavefunctions using Slater-type orbital basis sets.The calculated results for electric multipole moments of these molecules are in good agreement with the theoretical andexperimental ones.
The gravitational time delay in the field of a slowly moving body with arbitrary multipoles
Energy Technology Data Exchange (ETDEWEB)
Soffel, Michael H., E-mail: michael.soffel@tu-dresden.de [Shanghai Astronomical Observatory, 80 Nandan Road, Shanghai, 200030 (China); Lohmann Observatory, Helmholtzstrasse 10, D-01062 Dresden (Germany); Han, Wen-Biao, E-mail: wbhan@shao.ac.cn [Shanghai Astronomical Observatory, 80 Nandan Road, Shanghai, 200030 (China)
2015-02-06
We calculate the time delay of light in the gravitational field of a slowly moving body with arbitrary multipoles (mass and spin multipole moments) by the Time-Transfer-Function (TTF) formalism. The parameters we use, first introduced by Kopeikin for a gravitational source at rest, make the integration of the TTF very elegant and simple. Results completely coincide with expressions from the literature. The results for a moving body (with constant velocity) with complete multipole-structure are new, according to our knowledge. - Highlights: • The Time-Transfer-Function (TTF) is used to calculate the gravitational time delay. • The time delay for a body with arbitrary multipoles at rest is calculated in a very simply manner. • The gravitational time delay induced by a slowly moving body with arbitrary multipoles is derived for the first time.
Optimal design of a new multipole bilayer magnetorheological brake
Shiao, Yaojung; Ngoc, Nguyen Anh; Lai, Chien-Hung
2016-11-01
This article presents a new high-torque multipole bilayer magneto-rheological brake (MRB). This MRB has a unique structural design with multiple electromagnetic poles and multiple media layers of magnetorheological fluid (MRF). The MRB has two rotors located on the outer and inner sides of a six-pole stator, and therefore, it can provide higher torque and a larger torque-to-volume ratio (TVR) than conventional single- or multipole single-layer MRBs can. Moreover, the problem of potential MRF leakage is solved by using cylindrical separator rings around the stator. In this study, first, the structure of the proposed MRB is introduced. An analog magnetic circuit was built for the MRB to investigate the effects of the MRB parameters on the magnetic field intensity of the MRF layers. In addition, a 3D electromagnetic model of the MRB was developed to simulate and examine the magnetic flux intensity and corresponding braking torque. An approximate optimization method was then applied to obtain the optimal geometric dimensions for the major dimensional parameters of the MRB. The MRB was manufactured and tested to validate its torque and dynamic characteristics. The results showed that the proposed MRB exhibited great enhancement of the braking torque and TVR.
Alleviating the tension at low multipole through Axion Monodromy
Meerburg, P Daniel
2014-01-01
There exists some tension on large scales between the Planck data and the LCDM concordance model of the Universe, which has been amplified by the recently claimed discovery of non-zero tensor to scalar ratio $r$. At the same time, the current best-fit value of $r$ suggests large field inflation delta phi>M_p, which requires a UV complete description of inflation. A very promising working example that predicts large tensor modes and can be UV completed is axion monodromy inflation. This realization of inflation naturally produces oscillating features, as consequence of a broken shift symmetry. We analyse a combination of Planck, ACT, SPT, WMAP low l polarization and BICEP2 data, and show a long wavelength feature from a periodic potential can alleviate the tension at low multipoles with an improvement delta chi^2 ~2.5-4 per degree of freedom, depending on the level of foreground subtraction. As with an introduction of running, one expects that any scale dependence should lead to a worsened fit at high multipol...
Scalable force directed graph layout algorithms using fast multipole methods
Yunis, Enas Abdulrahman
2012-06-01
We present an extension to ExaFMM, a Fast Multipole Method library, as a generalized approach for fast and scalable execution of the Force-Directed Graph Layout algorithm. The Force-Directed Graph Layout algorithm is a physics-based approach to graph layout that treats the vertices V as repelling charged particles with the edges E connecting them acting as springs. Traditionally, the amount of work required in applying the Force-Directed Graph Layout algorithm is O(|V|2 + |E|) using direct calculations and O(|V| log |V| + |E|) using truncation, filtering, and/or multi-level techniques. Correct application of the Fast Multipole Method allows us to maintain a lower complexity of O(|V| + |E|) while regaining most of the precision lost in other techniques. Solving layout problems for truly large graphs with millions of vertices still requires a scalable algorithm and implementation. We have been able to leverage the scalability and architectural adaptability of the ExaFMM library to create a Force-Directed Graph Layout implementation that runs efficiently on distributed multicore and multi-GPU architectures. © 2012 IEEE.
A Multipole Expansion Method for Analyzing Lightning Field Changes
Koshak, William J.; Krider, E. Philip; Murphy, Martin J.
1999-01-01
Changes in the surface electric field are frequently used to infer the locations and magnitudes of lightning-caused changes in thundercloud charge distributions. The traditional procedure is to assume that the charges that are effectively deposited by the flash can be modeled either as a single point charge (the Q model) or a point dipole (the P model). The Q model has four unknown parameters and provides a good description of many cloud-to-ground (CG) flashes. The P model has six unknown parameters and describes many intracloud (IC) discharges. In this paper we introduce a new analysis method that assumes that the change in the cloud charge can be described by a truncated multipole expansion, i.e., there are both monopole and dipole terms in the unknown source distribution, and both terms are applied simultaneously. This method can be used to analyze CG flashes that are accompanied by large changes in the cloud dipole moment and complex IC discharges. If there is enough information content in the measurements, the model can also be generalized to include quadrupole and higher order terms. The parameters of the charge moments are determined using a dme-dimensional grid search in combination with a linear inversion, and because of this, local minima in the error function and the associated solution ambiguities are avoided. The multipole method has been tested on computer-simulated sources and on natural lightning at the NASA Kennedy Space Center and U.S. Air Force Eastern Range.
On the Fly Doppler Broadening Using Multipole Representation
Energy Technology Data Exchange (ETDEWEB)
Khassenov, Azamat; Choi, Sooyoung; Lee, Deokjung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)
2015-05-15
On the Fly Doppler broadening is the technique to avoid pre-generation of the microscopic cross section, in other words, reduce the amount of storage. Currently, there are different types of formalisms used by NJOY code to generate reaction cross section and accomplish its Doppler broadening. Single-Level Breit-Wigner (SLBW) formalism is limited to well-separated resonances, in other words, it does not consider interference between energy levels. Multi-Level Breit- Wigner formalism (MLBW) was tested as the candidate for the cross section generation in the Monte Carlo code, which is under development in UNIST. According to the results, MLBW method requires huge amount of computational time to produce cross section at certain energy point. Reich-Moore (RM) technique can generate only 0K cross section, which means that it cannot produce broaden cross section directly from resonance parameters. The first step was to convert resonance parameters given in nuclear data file into multipoles. MPR shows very high potential to be used as the formalism in the on-the-fly Doppler broadening module of MCS. One of the main reasons is that comparison of the time cost shown in Table IV supports application of multipole representation.
Long-range interactions between Rydberg atoms
Deiglmayr, Johannes
2016-10-01
We present an overview over theoretical models to describe adiabatic potential-energy curves, experimental excitation spectra, and electronic and nuclear dynamics in interacting Rydberg-atom pairs at large internuclear separations. The potential-energy curves and molecular wavefunctions are determined from the multipole expansion of the static Coulomb interaction which is evaluated numerically in a product basis of atomic orbitals. The convergence of this approach both in the truncation of the multipole expansion as well as in the size of the product basis is discussed, and the comparison of simulated excitation spectra is established as a useful criterium to test the convergence of the calculation. We finally discuss the dynamics of electronic and nuclear motions of pairs of Rydberg atoms, focusing on the stability of ultralong range Rydberg molecules with respect to autoionization.
Energy Technology Data Exchange (ETDEWEB)
Schwörer, Magnus; Lorenzen, Konstantin; Mathias, Gerald; Tavan, Paul, E-mail: paul.tavan@physik.uni-muenchen.de [Lehrstuhl für BioMolekulare Optik, Ludwig–Maximilians Universität München, Oettingenstr. 67, 80538 München (Germany)
2015-03-14
Recently, a novel approach to hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations has been suggested [Schwörer et al., J. Chem. Phys. 138, 244103 (2013)]. Here, the forces acting on the atoms are calculated by grid-based density functional theory (DFT) for a solute molecule and by a polarizable molecular mechanics (PMM) force field for a large solvent environment composed of several 10{sup 3}-10{sup 5} molecules as negative gradients of a DFT/PMM hybrid Hamiltonian. The electrostatic interactions are efficiently described by a hierarchical fast multipole method (FMM). Adopting recent progress of this FMM technique [Lorenzen et al., J. Chem. Theory Comput. 10, 3244 (2014)], which particularly entails a strictly linear scaling of the computational effort with the system size, and adapting this revised FMM approach to the computation of the interactions between the DFT and PMM fragments of a simulation system, here, we show how one can further enhance the efficiency and accuracy of such DFT/PMM-MD simulations. The resulting gain of total performance, as measured for alanine dipeptide (DFT) embedded in water (PMM) by the product of the gains in efficiency and accuracy, amounts to about one order of magnitude. We also demonstrate that the jointly parallelized implementation of the DFT and PMM-MD parts of the computation enables the efficient use of high-performance computing systems. The associated software is available online.
Coe, J P; Paterson, M J
2013-01-01
The method of Monte Carlo configuration interaction (MCCI) [1,2] is applied to the calculation of multipole moments. We look at the ground and excited state dipole moments in carbon monoxide. We then consider the dipole of NO, the quadrupole of the nitrogen molecule and of BH. An octupole of methane is also calculated. We consider experimental geometries and also stretched bonds. We show that these non-variational quantities may be found to relatively good accuracy when compared with FCI results, yet using only a small fraction of the full configuration interaction space. MCCI results in the aug-cc-pVDZ basis are seen to generally have reasonably good agreement with experiment. We also investigate the performance of MCCI when applied to ionisation energies and electron affinities of atoms in an aug-cc-pVQZ basis. We compare the MCCI results with full configuration-interaction quantum Monte Carlo [3,4] and `exact' non-relativistic results [3,4]. We show that MCCI could be a useful alternative for the calculati...
A Generalized Grid-Based Fast Multipole Method for Integrating Helmholtz Kernels.
Parkkinen, Pauli; Losilla, Sergio A; Solala, Eelis; Toivanen, Elias A; Xu, Wen-Hua; Sundholm, Dage
2017-02-14
A grid-based fast multipole method (GB-FMM) for optimizing three-dimensional (3D) numerical molecular orbitals in the bubbles and cube double basis has been developed and implemented. The present GB-FMM method is a generalization of our recently published GB-FMM approach for numerically calculating electrostatic potentials and two-electron interaction energies. The orbital optimization is performed by integrating the Helmholtz kernel in the double basis. The steep part of the functions in the vicinity of the nuclei is represented by one-center bubbles functions, whereas the remaining cube part is expanded on an equidistant 3D grid. The integration of the bubbles part is treated by using one-center expansions of the Helmholtz kernel in spherical harmonics multiplied with modified spherical Bessel functions of the first and second kind, analogously to the numerical inward and outward integration approach for calculating two-electron interaction potentials in atomic structure calculations. The expressions and algorithms for massively parallel calculations on general purpose graphics processing units (GPGPU) are described. The accuracy and the correctness of the implementation has been checked by performing Hartree-Fock self-consistent-field calculations (HF-SCF) on H2, H2O, and CO. Our calculations show that an accuracy of 10(-4) to 10(-7) Eh can be reached in HF-SCF calculations on general molecules.
Multipole-preserving quadratures for discretization of functions
Genovese, Luigi
2015-01-01
Discretizing an analytic function on a uniform real-space grid is often done via a straightforward collocation method. This is ubiquitous in all areas of computational physics and quantum chemistry. An example in Density Functional Theory is given by the local external potential describing the interaction between ions and electrons. Also notable examples are given by the analytic functions defining compensation charges for range-separated electrostatic treatments. The accuracy of the collocation method used is therefore very important for the reliability of subsequent treatments like self-consistent field solutions of the electronic structure problems. When the real-space grid is too coarse, the collocation method introduces numerical artifacts typical of real-space treatments, like the so-called egg-box error, that may spoil the numerical stability of the description. We present in this paper a new quadrature scheme that is able to exactly preserve the multipoles of a given analytic function for a wide range...
Fast Multipole-Based Preconditioner for Sparse Iterative Solvers
Ibeid, Huda
2014-05-04
Among optimal hierarchical algorithms for the computational solution of elliptic problems, the Fast Multipole Method (FMM) stands out for its adaptability to emerging architectures, having high arithmetic intensity, tunable accuracy, and relaxed global synchronization requirements. We demonstrate that, beyond its traditional use as a solver in problems for which explicit free-space kernel representations are available, the FMM has applicability as a preconditioner in finite domain elliptic boundary value problems, by equipping it with boundary integral capability for finite boundaries and by wrapping it in a Krylov method for extensibility to more general operators. Compared with multilevel methods, it is capable of comparable algebraic convergence rates down to the truncation error of the discretized PDE, and it has superior multicore and distributed memory scalability properties on commodity architecture supercomputers.
Point sources and multipoles in inverse scattering theory
Potthast, Roland
2001-01-01
Over the last twenty years, the growing availability of computing power has had an enormous impact on the classical fields of direct and inverse scattering. The study of inverse scattering, in particular, has developed rapidly with the ability to perform computational simulations of scattering processes and led to remarkable advances in a range of applications, from medical imaging and radar to remote sensing and seismic exploration. Point Sources and Multipoles in Inverse Scattering Theory provides a survey of recent developments in inverse acoustic and electromagnetic scattering theory. Focusing on methods developed over the last six years by Colton, Kirsch, and the author, this treatment uses point sources combined with several far-reaching techniques to obtain qualitative reconstruction methods. The author addresses questions of uniqueness, stability, and reconstructions for both two-and three-dimensional problems.With interest in extracting information about an object through scattered waves at an all-ti...
Real space electrostatics for multipoles. III. Dielectric Properties
Lamichhane, Madan; Newman, Kathie E; Gezelter, J Daniel
2016-01-01
In the first two papers in this series, we developed new shifted potential (SP), gradient shifted force (GSF), and Taylor shifted force (TSF) real-space methods for multipole interactions in condensed phase simulations. Here, we discuss the dielectric properties of fluids that emerge from simulations using these methods. Most electrostatic methods (including the Ewald sum) require correction to the conducting boundary fluctuation formula for the static dielectric constants, and we discuss the derivation of these corrections for the new real space methods. For quadrupolar fluids, the analogous material property is the quadrupolar susceptibility. As in the dipolar case, the fluctuation formula for the quadrupolar susceptibility has corrections that depend on the electrostatic method being utilized. One of the most important effects measured by both the static dielectric and quadrupolar susceptibility is the ability to screen charges embedded in the fluid. We use potentials of mean force between solvated ions to...
Planar Multipol-Resonance-Probe: A Spectral Kinetic Approach
Friedrichs, Michael; Gong, Junbo; Brinkmann, Ralf Peter; Oberrath, Jens; Wilczek, Sebastian
2016-09-01
Measuring plasma parameters, e.g. electron density and electron temperature, is an important procedure to verify the stability and behavior of a plasma process. For this purpose the multipole resonance probe (MRP) represents a satisfying solution to measure the electron density. However the influence of the probe on the plasma through its physical presence makes it unattractive for some processes in industrial application. A solution to combine the benefits of the spherical MRP with the ability to integrate the probe into the plasma reactor is introduced by the planar model of the MRP (pMRP). Introducing the spectral kinetic formalism leads to a reduced simulation-circle compared to particle-in-cell simulations. The model of the pMRP is implemented and first simulation results are presented.
Collisionless Spectral Kinetic Simulation of Ideal Multipole Resonance Probe
Gong, Junbo; Wilczek, Sebastian; Szeremley, Daniel; Oberrath, Jens; Eremin, Denis; Dobrygin, Wladislaw; Schilling, Christian; Friedrichs, Michael; Brinkmann, Ralf Peter
2016-09-01
Active Plasma Resonance Spectroscopy denotes a class of industry-compatible plasma diagnostic methods which utilize the natural ability of plasmas to resonate on or near the electron plasma frequency ωpe. One particular realization of APRS with a high degree of geometric and electric symmetry is the Multipole Resonance Probe (MRP). The Ideal MRP(IMRP) is an even more symmetric idealization which is suited for theoretical investigations. In this work, a spectral kinetic scheme is presented to investigate the behavior of the IMRP in the low pressure regime. However, due to the velocity difference, electrons are treated as particles whereas ions are only considered as stationary background. In the scheme, the particle pusher integrates the equations of motion for the studied particles, the Poisson solver determines the electric field at each particle position. The proposed method overcomes the limitation of the cold plasma model and covers kinetic effects like collisionless damping.
Elliptical multipole wiggler beamlines at the advanced photon source
Energy Technology Data Exchange (ETDEWEB)
Beno, M.A. E-mail: beno@anl.gov; Kurtz, C.; Munkholm, A.; Ruett, U.; Engbretson, M.; Jennings, G.; Linton, J.; Knapp, G.S.; Montano, P.A
2001-07-21
The Basic Energy Sciences Synchrotron Radiation Center Collaborative Access Team has built three independent beamlines, which simultaneously utilize the X-ray radiation from an elliptical multipole wiggler, located at Sector 11 of the Advanced Photon Source. This insertion device produces circularly polarized X-rays on-axis and linearly polarized X-rays above and below the ring plane. The lower linearly polarized radiation is used in the monochromatic 11ID-D station for scattering and spectroscopy experiments in the 5-40 keV range. The on-axis circularly polarized photons are used for magnetic Compton scattering experiments in the 11ID-B station. The upper linearly polarized radiation is utilized by the high-energy diffraction station, 11ID-C. We report here on the beamline optics and experimental station equipment.
Pipelining the Fast Multipole Method over a Runtime System
Agullo, Emmanuel; Coulaud, Olivier; Darve, Eric; Messner, Matthias; Toru, Takahashi
2012-01-01
Fast Multipole Methods (FMM) are a fundamental operation for the simulation of many physical problems. The high performance design of such methods usually requires to carefully tune the algorithm for both the targeted physics and the hardware. In this paper, we propose a new approach that achieves high performance across architectures. Our method consists of expressing the FMM algorithm as a task flow and employing a state-of-the-art runtime system, StarPU, in order to process the tasks on the different processing units. We carefully design the task flow, the mathematical operators, their Central Processing Unit (CPU) and Graphics Processing Unit (GPU) implementations, as well as scheduling schemes. We compute potentials and forces of 200 million particles in 48.7 seconds on a homogeneous 160 cores SGI Altix UV 100 and of 38 million particles in 13.34 seconds on a heterogeneous 12 cores Intel Nehalem processor enhanced with 3 Nvidia M2090 Fermi GPUs.
An adaptive fast multipole accelerated Poisson solver for complex geometries
Askham, T.; Cerfon, A. J.
2017-09-01
We present a fast, direct and adaptive Poisson solver for complex two-dimensional geometries based on potential theory and fast multipole acceleration. More precisely, the solver relies on the standard decomposition of the solution as the sum of a volume integral to account for the source distribution and a layer potential to enforce the desired boundary condition. The volume integral is computed by applying the FMM on a square box that encloses the domain of interest. For the sake of efficiency and convergence acceleration, we first extend the source distribution (the right-hand side in the Poisson equation) to the enclosing box as a C0 function using a fast, boundary integral-based method. We demonstrate on multiply connected domains with irregular boundaries that this continuous extension leads to high accuracy without excessive adaptive refinement near the boundary and, as a result, to an extremely efficient ;black box; fast solver.
Fourier-Based Fast Multipole Method for the Helmholtz Equation
Cecka, Cris
2013-01-01
The fast multipole method (FMM) has had great success in reducing the computational complexity of solving the boundary integral form of the Helmholtz equation. We present a formulation of the Helmholtz FMM that uses Fourier basis functions rather than spherical harmonics. By modifying the transfer function in the precomputation stage of the FMM, time-critical stages of the algorithm are accelerated by causing the interpolation operators to become straightforward applications of fast Fourier transforms, retaining the diagonality of the transfer function, and providing a simplified error analysis. Using Fourier analysis, constructive algorithms are derived to a priori determine an integration quadrature for a given error tolerance. Sharp error bounds are derived and verified numerically. Various optimizations are considered to reduce the number of quadrature points and reduce the cost of computing the transfer function. © 2013 Society for Industrial and Applied Mathematics.
The Formation of Multipoles during the High-Temperature Creep of Austenitic Stainless Steels
DEFF Research Database (Denmark)
Howell, J.; Nielsson, O.; Horsewell, Andy
1981-01-01
It is shown that multipole dislocation configurations can arise during power-law creep of certain austenitic stainless steels. These multipoles have been analysed in some detail for two particular steels (Alloy 800 and a modified AISI 316L) and it is suggested that they arise either during...... instantaneous loading or during the primary creep stage. Trace analysis has shown that the multipoles are confined to {1 1 1} planes during primary creep but are not necessarily confined to these planes during steady-state creep unless they are pinned by interstitials....
Analytical study of the conjecture rule for the combination of multipole effects in LHC
Guignard, Gilbert
1997-01-01
This paper summarizes the analytical investigation done on the conjecture law found by tracking for the effect on the dynamic aperture of the combination of two multipoles of various order. A one-dimensional model leading to an integrable system has been used to find closed formulae for the dynamic aperture associated with a fully distributed multipole. The combination has then been studied and the resulting expression compared with the assumed conjecture law. For integrated multipoles small with respect to the focusing strength, the conjecture appears to hold, though with an exponent different from the one expected by crude reasoning.
The gravitational time delay in the field of a slowly moving body with arbitrary multipoles
Soffel, Michael H
2014-01-01
We calculate the time delay of light in the gravitational field of a slowly moving body with arbitrary multipoles (mass and spin multipole moments) by the time-transfer-function (TTF) formalism. The parameters we use, first introduced by Kopeikin for a gravitational source at rest, make the integration of the TTF very elegant and simple. Results completely coincide with expressions from the literature. The results for a moving body (with constant velocity) with complete multipole-structure are new, according to our knowledge.
Energy Technology Data Exchange (ETDEWEB)
Chung, Ting-Yi; Huang, Szu-Jung; Fu, Huang-Wen; Chang, Ho-Ping; Chang, Cheng-Hsiang [National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Hwang, Ching-Shiang [National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Department of Electrophysics, National Chiao Tung University, Hsinchu 30050, Taiwan (China)
2016-08-01
The effect of an APPLE II-type elliptically polarized undulator (EPU) on the beam dynamics were investigated using active and passive methods. To reduce the tune shift and improve the injection efficiency, dynamic multipole errors were compensated using L-shaped iron shims, which resulted in stable top-up operation for a minimum gap. The skew quadrupole error was compensated using a multipole corrector, which was located downstream of the EPU for minimizing betatron coupling, and it ensured the enhancement of the synchrotron radiation brightness. The investigation methods, a numerical simulation algorithm, a multipole error correction method, and the beam-based measurement results are discussed.
Łazarski, Roman; Burow, Asbjörn Manfred; Grajciar, Lukáš; Sierka, Marek
2016-10-30
A full implementation of analytical energy gradients for molecular and periodic systems is reported in the TURBOMOLE program package within the framework of Kohn-Sham density functional theory using Gaussian-type orbitals as basis functions. Its key component is a combination of density fitting (DF) approximation and continuous fast multipole method (CFMM) that allows for an efficient calculation of the Coulomb energy gradient. For exchange-correlation part the hierarchical numerical integration scheme (Burow and Sierka, Journal of Chemical Theory and Computation 2011, 7, 3097) is extended to energy gradients. Computational efficiency and asymptotic O(N) scaling behavior of the implementation is demonstrated for various molecular and periodic model systems, with the largest unit cell of hematite containing 640 atoms and 19,072 basis functions. The overall computational effort of energy gradient is comparable to that of the Kohn-Sham matrix formation. © 2016 Wiley Periodicals, Inc.
Energy Technology Data Exchange (ETDEWEB)
Poursina, Mohammad [Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721 (United States); Anderson, Kurt S. [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute (RPI), Troy, NY 12180 (United States)
2014-08-01
This paper presents a novel algorithm to approximate the long-range electrostatic potential field in the Cartesian coordinates applicable to 3D coarse-grained simulations of biopolymers. In such models, coarse-grained clusters are formed via treating groups of atoms as rigid and/or flexible bodies connected together via kinematic joints. Therefore, multibody dynamic techniques are used to form and solve the equations of motion of such coarse-grained systems. In this article, the approximations for the potential fields due to the interaction between a highly negatively/positively charged pseudo-atom and charged particles, as well as the interaction between clusters of charged particles, are presented. These approximations are expressed in terms of physical and geometrical properties of the bodies such as the entire charge, the location of the center of charge, and the pseudo-inertia tensor about the center of charge of the clusters. Further, a novel substructuring scheme is introduced to implement the presented far-field potential evaluations in a binary tree framework as opposed to the existing quadtree and octree strategies of implementing fast multipole method. Using the presented Lagrangian grids, the electrostatic potential is recursively calculated via sweeping two passes: assembly and disassembly. In the assembly pass, adjacent charged bodies are combined together to form new clusters. Then, the potential field of each cluster due to its interaction with faraway resulting clusters is recursively calculated in the disassembly pass. The method is highly compatible with multibody dynamic schemes to model coarse-grained biopolymers. Since the proposed method takes advantage of constant physical and geometrical properties of rigid clusters, improvement in the overall computational cost is observed comparing to the tradition application of fast multipole method.
Long-range interactions of excited He atoms with the alkaline earth atoms Mg, Ca, and Sr
Zhang, J.-Y.
2013-04-05
Dispersion coefficients for the long-range interactions of the first four excited states of He, i.e., He(2 1, 3 S) and He(2 1, 3 P), with the low-lying states of the alkaline earth atoms Mg, Ca, and Sr are calculated by summing over the reduced matrix elements of multipole transition operators.
A detailed proof of the fundamental theorem of STF multipole expansion in linearized gravity
Zschocke, Sven
2014-01-01
The linearized field equations of general relativity in harmonic coordinates are given by an inhomogeneous wave equation. In the region exterior to the matter field, the retarded solution of this wave equation can be expanded in terms of 10 Cartesian symmetric and tracefree (STF) multipoles in post-Minkowskian approximation. For such a multipole decomposition only three and rather weak assumptions are required: 1. No-incoming radiation condition. 2. The matter source is spatially compact. 3. A spherical expansion for the metric outside the matter source is possible. During the last decades, the STF multipole expansion has been established as a powerful tool in several fields of gravitational physics: celestial mechanics, theory of gravitational waves and in the theory of light propagation and astrometry. But despite its formidable importance, an explicit proof of the fundamental theorem of STF multipole expansion has not been presented thus far, while only some parts of it are distributed into several publica...
Review of non-Gaussianity at low and high multipoles from WMAP data
Verkhodanov, O. V.; Naselsky, P. D.; Chiang, L.-Y.; Doroshkevich, A. G.; Novikov, I. D.
2008-09-01
We review problems of non-Gaussianity analysis of the WMAP data. The non-Gaussianity has been detected by different methods in several multipole ranges. To our opinion, it could be due to some systematic effects of data analysis.
Adaptation and performance of the fast multipole method for dipolar systems
Energy Technology Data Exchange (ETDEWEB)
Gorn, N.L. E-mail: db@innovent-jena.de; Berkov, D.V
2004-05-01
We have developed a new specialized version of the fast multipole method (FMM) for dipolar systems. For this purpose we have derived general expressions of the multipole expansion coefficients (in spherical coordinates) for a system of point dipoles with the potential phi (cursive,open) Greek{sub dip}{approx}1/r{sup 2}. Our version is especially useful for simulations of fine magnetic particle systems (magnetic nanocomposites, ferrofluids), molecular dipolar fluids or electric dipolar glasses.
Cumulant expansions for atmospheric flows
Ait-Chaalal, Farid; Meyer, Bettina; Marston, J B
2015-01-01
The equations governing atmospheric flows are nonlinear, and consequently the hierarchy of cumulant equations is not closed. But because atmospheric flows are inhomogeneous and anisotropic, the nonlinearity may manifests itself only weakly through interactions of mean fields with disturbances such as thermals or eddies. In such situations, truncations of the hierarchy of cumulant equations hold promise as a closure strategy. We review how truncations at second order can be used to model and elucidate the dynamics of turbulent atmospheric flows. Two examples are considered. First, we study the growth of a dry convective boundary layer, which is heated from below, leading to turbulent upward energy transport and growth of the boundary layer. We demonstrate that a quasilinear truncation of the equations of motion, in which interactions of disturbances among each other are neglected but interactions with mean fields are taken into account, can successfully capture the growth of the convective boundary layer. Seco...
Electro-cumulation CNF project
Grishin, V G
2000-01-01
bound or free ion current within solid substances; non-plain symmetry; cumulation of the ion interaction. Experimental result: an Ice SuperPolarization. Cold nuclear fusion ? At http://www.shortway.to/to2084 . Keywords: ion, current, solid, symmetry, cumulation, cold nuclear fusion, polarization, depolarization, ionic conductor, superionic conductor, ice, crystal, strain, V-center, V-centre, doped crystal, interstitial impurity, intrinsic color center, high pressure technology, Bridgman, experiment, crowdion, dielectric, proton, layer, defect, lattice, dynamics, electromigration, mobility, muon catalysis, concentration, doping, dopant, conductivity, pycnonuclear reaction, permittivity, dielectric constant, point defects, interstitials, polarizability, imperfection, defect centers, glass, epitaxy, sodium hydroxide, metallic substrate, crystallization, point, tip, susceptibility, ferroelectric, ordering, force, correlation, collective, shift, distortion, coalescence, crowdions, electrolysis.
Directory of Open Access Journals (Sweden)
Ingo Klein
2016-07-01
Full Text Available A new kind of entropy will be introduced which generalizes both the differential entropy and the cumulative (residual entropy. The generalization is twofold. First, we simultaneously define the entropy for cumulative distribution functions (cdfs and survivor functions (sfs, instead of defining it separately for densities, cdfs, or sfs. Secondly, we consider a general “entropy generating function” φ, the same way Burbea et al. (IEEE Trans. Inf. Theory 1982, 28, 489–495 and Liese et al. (Convex Statistical Distances; Teubner-Verlag, 1987 did in the context of φ-divergences. Combining the ideas of φ-entropy and cumulative entropy leads to the new “cumulative paired φ-entropy” ( C P E φ . This new entropy has already been discussed in at least four scientific disciplines, be it with certain modifications or simplifications. In the fuzzy set theory, for example, cumulative paired φ-entropies were defined for membership functions, whereas in uncertainty and reliability theories some variations of C P E φ were recently considered as measures of information. With a single exception, the discussions in the scientific disciplines appear to be held independently of each other. We consider C P E φ for continuous cdfs and show that C P E φ is rather a measure of dispersion than a measure of information. In the first place, this will be demonstrated by deriving an upper bound which is determined by the standard deviation and by solving the maximum entropy problem under the restriction of a fixed variance. Next, this paper specifically shows that C P E φ satisfies the axioms of a dispersion measure. The corresponding dispersion functional can easily be estimated by an L-estimator, containing all its known asymptotic properties. C P E φ is the basis for several related concepts like mutual φ-information, φ-correlation, and φ-regression, which generalize Gini correlation and Gini regression. In addition, linear rank tests for scale that
High Heat-Load Slits for the PLS Multipole Wiggler
Gil, Kyehwan; Kim, Young-Chan; Lee, Heung-Soo; Wha Chung, Chin
2005-01-01
The HFMX (High Flux Macromolecular X-ray crystallography) beamline under commissioning at Pohang Accelerator Laboratory uses beam from a multipole wiggler for MAD experiment. Two horizontal and vertical slits relevant to high heat load are installed at its front-end. In order to treat high heat load and to reduce beam scattering, the horizontal slit has two glidcop blocks with 10° of vertical inclination and its tungsten blades defining beam size are bolted on backsides of both blocks. The blocks of the slit are adjusted on fixed slides by two actuating bars, respectively. Water through channels machined along the actuating bars cool down the heat load of both blocks. The vertical slit has the same structure as the horizontal slit except its installation direction and angle of vertical inclination. The installed slits show stable operation performance and no alignment for the blocks is required by virtue of a pair of blocks translating on slides. The cooling performance of two slits is also shown to ...
Multipole analysis of redshift-space distortions around cosmic voids
Hamaus, Nico; Cousinou, Marie-Claude; Pisani, Alice; Aubert, Marie; Escoffier, Stéphanie; Weller, Jochen
2017-07-01
We perform a comprehensive redshift-space distortion analysis based on cosmic voids in the large-scale distribution of galaxies observed with the Sloan Digital Sky Survey. To this end, we measure multipoles of the void-galaxy cross-correlation function and compare them with standard model predictions in cosmology. Merely considering linear-order theory allows us to accurately describe the data on the entire available range of scales and to probe void-centric distances down to about 2 h-1Mpc. Common systematics, such as the Fingers-of-God effect, scale-dependent galaxy bias, and nonlinear clustering do not seem to play a significant role in our analysis. We constrain the growth rate of structure via the redshift-space distortion parameter β at two median redshifts, β(bar z=0.32)=0.599+0.134-0.124 and β(bar z=0.54)=0.457+0.056-0.054, with a precision that is competitive with state-of-the-art galaxy-clustering results. While the high-redshift constraint perfectly agrees with model expectations, we observe a mild 2σ deviation at bar z=0.32, which increases to 3σ when the data is restricted to the lowest available redshift range of 0.15
A task parallel implementation of fast multipole methods
Taura, Kenjiro
2012-11-01
This paper describes a task parallel implementation of ExaFMM, an open source implementation of fast multipole methods (FMM), using a lightweight task parallel library MassiveThreads. Although there have been many attempts on parallelizing FMM, experiences have almost exclusively been limited to formulation based on flat homogeneous parallel loops. FMM in fact contains operations that cannot be readily expressed in such conventional but restrictive models. We show that task parallelism, or parallel recursions in particular, allows us to parallelize all operations of FMM naturally and scalably. Moreover it allows us to parallelize a \\'\\'mutual interaction\\'\\' for force/potential evaluation, which is roughly twice as efficient as a more conventional, unidirectional force/potential evaluation. The net result is an open source FMM that is clearly among the fastest single node implementations, including those on GPUs; with a million particles on a 32 cores Sandy Bridge 2.20GHz node, it completes a single time step including tree construction and force/potential evaluation in 65 milliseconds. The study clearly showcases both programmability and performance benefits of flexible parallel constructs over more monolithic parallel loops. © 2012 IEEE.
On the origin dependence of multipole moments in electromagnetism
Energy Technology Data Exchange (ETDEWEB)
Visschere, Patrick De [Ghent University, Department ELIS Sint-Pietersnieuwstraat 41, B-9000 Gent (Belgium)
2006-10-07
The standard description of material media in electromagnetism is based on multipoles. It is well known that these moments depend on the point of reference chosen, except for the lowest order. It is shown that this 'origin dependence' is not unphysical as has been claimed in the literature but forms only part of the effect of moving the point of reference. When the complementary part is also taken into account then different points of reference lead to different but equivalent descriptions of the same physical reality. This is shown at the microscopic as well as at the macroscopic level. A similar interpretation is valid regarding the 'origin dependence' of the reflection coefficients for reflection on a semi-infinite medium. We show that the 'transformation theory' which has been proposed to remedy this situation (and which is thus not needed) is unphysical since the transformation considered does not leave the boundary conditions invariant.
Data-driven execution of fast multipole methods
Ltaief, Hatem
2013-09-17
Fast multipole methods (FMMs) have O (N) complexity, are compute bound, and require very little synchronization, which makes them a favorable algorithm on next-generation supercomputers. Their most common application is to accelerate N-body problems, but they can also be used to solve boundary integral equations. When the particle distribution is irregular and the tree structure is adaptive, load balancing becomes a non-trivial question. A common strategy for load balancing FMMs is to use the work load from the previous step as weights to statically repartition the next step. The authors discuss in the paper another approach based on data-driven execution to efficiently tackle this challenging load balancing problem. The core idea consists of breaking the most time-consuming stages of the FMMs into smaller tasks. The algorithm can then be represented as a directed acyclic graph where nodes represent tasks and edges represent dependencies among them. The execution of the algorithm is performed by asynchronously scheduling the tasks using the queueing and runtime for kernels runtime environment, in a way such that data dependencies are not violated for numerical correctness purposes. This asynchronous scheduling results in an out-of-order execution. The performance results of the data-driven FMM execution outperform the previous strategy and show linear speedup on a quad-socket quad-core Intel Xeon system.Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.
Fast multipole method applied to Lagrangian simulations of vortical flows
Ricciardi, Túlio R.; Wolf, William R.; Bimbato, Alex M.
2017-10-01
Lagrangian simulations of unsteady vortical flows are accelerated by the multi-level fast multipole method, FMM. The combination of the FMM algorithm with a discrete vortex method, DVM, is discussed for free domain and periodic problems with focus on implementation details to reduce numerical dissipation and avoid spurious solutions in unsteady inviscid flows. An assessment of the FMM-DVM accuracy is presented through a comparison with the direct calculation of the Biot-Savart law for the simulation of the temporal evolution of an aircraft wake in the Trefftz plane. The role of several parameters such as time step restriction, truncation of the FMM series expansion, number of particles in the wake discretization and machine precision is investigated and we show how to avoid spurious instabilities. The FMM-DVM is also applied to compute the evolution of a temporal shear layer with periodic boundary conditions. A novel approach is proposed to achieve accurate solutions in the periodic FMM. This approach avoids a spurious precession of the periodic shear layer and solutions are shown to converge to the direct Biot-Savart calculation using a cotangent function.
Infrared Extrapolations of Electromagnetic Multipole Moments and Transitions
Odell, Daniel; Papenbrock, Thomas; Platter, Lucas
2017-01-01
Basis truncations introduce systematic errors in observables calculated by representing the nuclear Hamiltonian in finite Hilbert spaces. Recent studies of the infrared convergence of finite basis calculations of energies and radii have led to accurate descriptions of numerical data. I will discuss how these concepts can be applied to the study of bound-state quadrupole moments and transitions as well as multipole transitions between bound-states and the continuum. I will show that good agreement is obtained between analytically derived and numerically computed convergence behavior in finite harmonic oscillator spaces for the nucleon-nucleon system. This opens the way to a more precise understanding of structure and reactions involving heavier nuclei. U.S. Dept of Energy, Office of Science under Nos. DEFG02-96ER40963, DE-AC05-00OR22725, DE-SC0008499; US-Israel Binational Science Foundation under Grant No. 2012212; National Science Foundation under Grant No. PHY-1516077 and No. PHY-1555030.
Scalable fast multipole methods for vortex element methods
Hu, Qi
2012-11-01
We use a particle-based method to simulate incompressible flows, where the Fast Multipole Method (FMM) is used to accelerate the calculation of particle interactions. The most time-consuming kernelsâ\\'the Biot-Savart equation and stretching term of the vorticity equationâ\\'are mathematically reformulated so that only two Laplace scalar potentials are used instead of six, while automatically ensuring divergence-free far-field computation. Based on this formulation, and on our previous work for a scalar heterogeneous FMM algorithm, we develop a new FMM-based vortex method capable of simulating general flows including turbulence on heterogeneous architectures, which distributes the work between multi-core CPUs and GPUs to best utilize the hardware resources and achieve excellent scalability. The algorithm also uses new data structures which can dynamically manage inter-node communication and load balance efficiently but with only a small parallel construction overhead. This algorithm can scale to large-sized clusters showing both strong and weak scalability. Careful error and timing trade-off analysis are also performed for the cutoff functions induced by the vortex particle method. Our implementation can perform one time step of the velocity+stretching for one billion particles on 32 nodes in 55.9 seconds, which yields 49.12 Tflop/s. © 2012 IEEE.
Instability of reconstruction of the low CMB multipoles
DEFF Research Database (Denmark)
Naselsky, Pavel D.; Verkhodanov, Oleg V.; Nielsen, Mikkel T. B.
2007-01-01
We discuss the problem of the bias of the Internal Linear Combination (ILC) CMB map and show that it is closely related to the coefficient of cross-correlation K(l) of the true CMB and the foreground for each multipole l. We present analysis of the cross-correlation for the WMAP ILC quadrupole...... and octupole from the first (ILC(I)) and the third (ILC(III)) year data releases and show that these correlations are about -0.52-0.6. Analysing 10^4 Monte Carlo simulations of the random Gaussian CMB signals, we show that the distribution function for the corresponding coefficient of the cross-correlation has...... of debiasing of the ILC CMB and pointed out that reconstruction of the bias seems to be very problematic due to statistical uncertainties. In addition, instability of the debiasing illuminates itself for the quadrupole and octupole components through the flip-effect, when the even (l+m) modes can...
The Algebra of the Cumulative Percent Operation.
Berry, Andrew J.
2002-01-01
Discusses how to help students avoid some pervasive reasoning errors in solving cumulative percent problems. Discusses the meaning of ."%+b%." the additive inverse of ."%." and other useful applications. Emphasizes the operational aspect of the cumulative percent concept. (KHR)
Adaptive strategies for cumulative cultural learning.
Ehn, Micael; Laland, Kevin
2012-05-21
The demographic and ecological success of our species is frequently attributed to our capacity for cumulative culture. However, it is not yet known how humans combine social and asocial learning to generate effective strategies for learning in a cumulative cultural context. Here we explore how cumulative culture influences the relative merits of various pure and conditional learning strategies, including pure asocial and social learning, critical social learning, conditional social learning and individual refiner strategies. We replicate the Rogers' paradox in the cumulative setting. However, our analysis suggests that strategies that resolved Rogers' paradox in a non-cumulative setting may not necessarily evolve in a cumulative setting, thus different strategies will optimize cumulative and non-cumulative cultural learning.
Lin, Dejun
2015-09-01
Accurate representation of intermolecular forces has been the central task of classical atomic simulations, known as molecular mechanics. Recent advancements in molecular mechanics models have put forward the explicit representation of permanent and/or induced electric multipole (EMP) moments. The formulas developed so far to calculate EMP interactions tend to have complicated expressions, especially in Cartesian coordinates, which can only be applied to a specific kernel potential function. For example, one needs to develop a new formula each time a new kernel function is encountered. The complication of these formalisms arises from an intriguing and yet obscured mathematical relation between the kernel functions and the gradient operators. Here, I uncover this relation via rigorous derivation and find that the formula to calculate EMP interactions is basically invariant to the potential kernel functions as long as they are of the form f(r), i.e., any Green's function that depends on inter-particle distance. I provide an algorithm for efficient evaluation of EMP interaction energies, forces, and torques for any kernel f(r) up to any arbitrary rank of EMP moments in Cartesian coordinates. The working equations of this algorithm are essentially the same for any kernel f(r). Recently, a few recursive algorithms were proposed to calculate EMP interactions. Depending on the kernel functions, the algorithm here is about 4-16 times faster than these algorithms in terms of the required number of floating point operations and is much more memory efficient. I show that it is even faster than a theoretically ideal recursion scheme, i.e., one that requires 1 floating point multiplication and 1 addition per recursion step. This algorithm has a compact vector-based expression that is optimal for computer programming. The Cartesian nature of this algorithm makes it fit easily into modern molecular simulation packages as compared with spherical coordinate-based algorithms. A
"Buddha's Light" of Cumulative Particles
Kopeliovich, Vladimir B; Potashnikova, Irina K
2014-01-01
We show analytically that in the cumulative particles production off nuclei multiple interactions lead to a glory-like backward focusing effect. Employing the small phase space method we arrived at a characteristic angular dependence of the production cross section $d\\sigma \\sim 1/ \\sqrt {\\pi - \\theta}$ near the strictly backward direction. This effect takes place for any number $n\\geq 3 $ of interactions of rescattered particle, either elastic or inelastic (with resonance excitations in intermediate states), when the final particle is produced near corresponding kinematical boundary. Such a behaviour of the cross section near the backward direction is in qualitative agreement with some of available data.
A Resource Cost Aware Cumulative
Simonis, Helmut; Hadzic, Tarik
We motivate and introduce an extension of the well-known cumulative constraint which deals with time and volume dependent cost of resources. Our research is primarily interested in scheduling problems under time and volume variable electricity costs, but the constraint equally applies to manpower scheduling when hourly rates differ over time and/or extra personnel incur higher hourly rates. We present a number of possible lower bounds on the cost, including a min-cost flow, different LP and MIP models, as well as greedy algorithms, and provide a theoretical and experimental comparison of the different methods.
Multipolar electrostatics for proteins: atom-atom electrostatic energies in crambin.
Yuan, Yongna; Mills, Matthew J L; Popelier, Paul L A
2014-02-15
Accurate electrostatics necessitates the use of multipole moments centered on nuclei or extra point charges centered away from the nuclei. Here, we follow the former alternative and investigate the convergence behavior of atom-atom electrostatic interactions in the pilot protein crambin. Amino acids are cut out from a Protein Data Bank structure of crambin, as single amino acids, di, or tripeptides, and are then capped with a peptide bond at each side. The atoms in the amino acids are defined through Quantum Chemical Topology (QCT) as finite volume electron density fragments. Atom-atom electrostatic energies are computed by means of a multipole expansion with regular spherical harmonics, up to a total interaction rank of L = ℓA+ ℓB + 1 = 10. The minimum internuclear distance in the convergent region of all the 15 possible types of atom-atom interactions in crambin that were calculated based on single amino acids are close to the values calculated from di and tripeptides. Values obtained at B3LYP/aug-cc-pVTZ and MP2/aug-cc-pVTZ levels are only slightly larger than those calculated at HF/6-31G(d,p) level. This convergence behavior is transferable to the well-known amyloid beta polypeptide Aβ1-42. Moreover, for a selected central atom, the influence of its neighbors on its multipole moments is investigated, and how far away this influence can be ignored is also determined. Finally, the convergence behavior of AMBER becomes closer to that of QCT with increasing internuclear distance.
A paradox of cumulative culture.
Kobayashi, Yutaka; Wakano, Joe Yuichiro; Ohtsuki, Hisashi
2015-08-21
Culture can grow cumulatively if socially learnt behaviors are improved by individual learning before being passed on to the next generation. Previous authors showed that this kind of learning strategy is unlikely to be evolutionarily stable in the presence of a trade-off between learning and reproduction. This is because culture is a public good that is freely exploited by any member of the population in their model (cultural social dilemma). In this paper, we investigate the effect of vertical transmission (transmission from parents to offspring), which decreases the publicness of culture, on the evolution of cumulative culture in both infinite and finite population models. In the infinite population model, we confirm that culture accumulates largely as long as transmission is purely vertical. It turns out, however, that introduction of even slight oblique transmission drastically reduces the equilibrium level of culture. Even more surprisingly, if the population size is finite, culture hardly accumulates even under purely vertical transmission. This occurs because stochastic extinction due to random genetic drift prevents a learning strategy from accumulating enough culture. Overall, our theoretical results suggest that introducing vertical transmission alone does not really help solve the cultural social dilemma problem. Copyright © 2015 Elsevier Ltd. All rights reserved.
a Detailed Proof of the Fundamental Theorem of STF Multipole Expansion in Linearized Gravity
Zschocke, Sven
2014-10-01
The linearized field equations of general relativity in harmonic coordinates are given by an inhomogeneous wave equation. In the region exterior to the matter field, the retarded solution of this wave equation can be expanded in terms of 10 Cartesian symmetric and tracefree (STF) multipoles in post-Minkowskian approximation. For such a multipole decomposition only three and rather weak assumptions are required: (1) No-incoming-radiation condition. (2) The matter source is spatially compact. (3) A spherical expansion for the metric outside the matter source is possible. During the last decades, the STF multipole expansion has been established as a powerful tool in several fields of gravitational physics: celestial mechanics, theory of gravitational waves and in the theory of light propagation and astrometry. But despite its formidable importance, an explicit proof of the fundamental theorem of STF multipole expansion has not been presented so far, while only some parts of it are distributed into several publications. In a technical but more didactical form, an explicit and detailed mathematical proof of each individual step of this important theorem of STF multipole expansion is represented.
Institute of Scientific and Technical Information of China (English)
Chang-Jun Zheng; Hai-Bo Chen; Lei-Lei Chen
2013-01-01
This paper presents a novel wideband fast multipole boundary element approach to 3D half-space/planesymmetric acoustic wave problems.The half-space fundamental solution is employed in the boundary integral equations so that the tree structure required in the fast multipole algorithm is constructed for the boundary elements in the real domain only.Moreover,a set of symmetric relations between the multipole expansion coefficients of the real and image domains are derived,and the half-space fundamental solution is modified for the purpose of applying such relations to avoid calculating,translating and saving the multipole/local expansion coefficients of the image domain.The wideband adaptive multilevel fast multipole algorithm associated with the iterative solver GMRES is employed so that the present method is accurate and efficient for both lowand high-frequency acoustic wave problems.As for exterior acoustic problems,the Burton-Miller method is adopted to tackle the fictitious eigenfrequency problem involved in the conventional boundary integral equation method.Details on the implementation of the present method are described,and numerical examples are given to demonstrate its accuracy and efficiency.
Energy Technology Data Exchange (ETDEWEB)
Safronova, U I; Safronova, A S; Beiersdorfer, P
2007-10-08
Transition rates and line strengths are calculated for electric-multipole (E2 and E3) and magnetic-multipole (M1, M2, and M3) transitions between 3s{sup 2}3p{sup 6}3d{sup 10}, 3s{sup 2}3p{sup 6}3d{sup 9}4l, 3s{sup 2}3p{sup 5}3d{sup 10}4l, and 3s3p{sup 6}3d{sup 10}4l states (with 4l = 4s, 4p, 4d, and 4f) in Ni-like ions with the nuclear charges ranging from Z = 34 to 100. Relativistic many-body perturbation theory (RMBPT), including the Breit interaction, is used to evaluate retarded multipole matrix elements. Transition energies used in the calculation of line strengths and transition rates are from second-order RMBPT. Lifetimes of the 3s{sup 2}3p{sup 6}3d{sup 9}4s levels are given for Z = 34-100. Taking into account that calculations were performed in a very broad range of Z, most of the data are presented in graphs as Z-dependencies. The full set of data is given only for Ni-like W ion. In addition, we also give complete results for the 3d4s{sup 3}D{sub 2}-3d4s {sup 3}D{sub 1} magnetic-dipole transition, as the transition may be observed in future experiments, which measure both transition energies and radiative rates. These atomic data are important in the modeling of radiation spectra from Ni-like multiply-charged ions generated in electron beam ion trap experiments as well as for laboratory plasma diagnostics including fusion research.
Energy Technology Data Exchange (ETDEWEB)
Bereau, Tristan, E-mail: bereau@mpip-mainz.mpg.de [Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany and Department of Chemistry, University of Basel, 4056 Basel (Switzerland); Lilienfeld, O. Anatole von [Department of Chemistry, Institute of Physical Chemistry, University of Basel, 4056 Basel, Switzerland and Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2014-07-21
We estimate polarizabilities of atoms in molecules without electron density, using a Voronoi tesselation approach instead of conventional density partitioning schemes. The resulting atomic dispersion coefficients are calculated, as well as many-body dispersion effects on intermolecular potential energies. We also estimate contributions from multipole electrostatics and compare them to dispersion. We assess the performance of the resulting intermolecular interaction model from dispersion and electrostatics for more than 1300 neutral and charged, small organic molecular dimers. Applications to water clusters, the benzene crystal, the anti-cancer drug ellipticine—intercalated between two Watson-Crick DNA base pairs, as well as six macro-molecular host-guest complexes highlight the potential of this method and help to identify points of future improvement. The mean absolute error made by the combination of static electrostatics with many-body dispersion reduces at larger distances, while it plateaus for two-body dispersion, in conflict with the common assumption that the simple 1/R{sup 6} correction will yield proper dissociative tails. Overall, the method achieves an accuracy well within conventional molecular force fields while exhibiting a simple parametrization protocol.
Self-similar oscillations of a Z pinch bounded by a magnetic multipole
Energy Technology Data Exchange (ETDEWEB)
Tendler, M.
1988-11-01
A new analytic, self-similar solution of the fluid equations with losses in a stabilized Z pinch is presented. A scaling is suggested for the net energy loss with plasma density and temperature typical for a Z pinch immersed in an external multipole magnetic field. The solution of the strongly nonlinear system of fluid equations is obtained by self-similar methods. Strongly aharmonic high frequency oscillations of the plasma parameters are found. It is emphasized that a static Z pinch cannot be stabilized by a stationary field of a magnetic multipole. Therefore the potentiality of these oscillations to affect the stability of Z pinches embedded in a magnetic multipole is investigated. The effect of the dynamic stabilization is considered by taking estimates.
Multipole analysis for electromagnetism and linearized gravity with irreducible Cartesian tensors
Energy Technology Data Exchange (ETDEWEB)
Damour, T.; Iyer, B.R. (Institut des Hautes Etudes Scientifiques 91440 Bures sur Yvette, France Departement d' Astrophysique Relativiste et de Cosmologie, Centre National de la Recherche Scientifique-Observatoire de Paris, 92195 Meudon CEDEX, France (FR))
1991-05-15
The relativistic time-dependent multipole expansion for electromagnetism and linearized gravity in the region outside a spatially compact source has been obtained directly using the formalism of irreducible Cartesian (i.e., symmetric trace-free) tensors. In the electromagnetic case, our results confirm the validity of the results obtained earlier by Campbell, Macek, and Morgan using the Debye potential formalism. However, in the more complicated linearized gravity case, the greater algebraic transparence of the Cartesian multipole approach has allowed us to obtain, for the first time, fully correct closed-form expressions for the time-dependent mass and spin multipole moments (the results of Campbell {ital et} {ital al}. for the mass moments turning out to be incorrect). The first two terms in the slow-motion expansion of the gravitational moments are explicitly calculated and shown to be equivalent to earlier results by Thorne and by Blanchet and Damour.
Energy Technology Data Exchange (ETDEWEB)
Kanduc, M; Podgornik, R [Department of Theoretical Physics, J Stefan Institute, SI-1000 Ljubljana (Slovenia); Naji, A [Department of Physics, Department of Chemistry and Biochemistry, Materials Research Laboratory, University of California, Santa Barbara, CA 93106 (United States); Jho, Y S; Pincus, P A [Materials Research Laboratory, University of California, Santa Barbara, CA 93106 (United States)
2009-10-21
We present general arguments for the importance, or lack thereof, of structure in the charge distribution of counterions for counterion-mediated interactions between bounding symmetrically charged surfaces. We show that on the mean field or weak coupling level, the charge quadrupole contributes the lowest order modification to the contact value theorem and thus to the intersurface electrostatic interactions. The image effects are non-existent on the mean field level even with multipoles. On the strong coupling level the quadrupoles and higher order multipoles contribute additional terms to the interaction free energy only in the presence of dielectric inhomogeneities. Without them, the monopole is the only multipole that contributes to the strong coupling electrostatics. We explore the consequences of these statements in all their generality.
Platonic topology and CMB fluctuations: Homotopy, anisotropy, and multipole selection rules
Kramer, Peter
2009-01-01
The Cosmic Microwave Background CMB originates from an early stage in the history of the universe. Observed low multipole contributions of CMB fluctuations have motivated the search for selection rules from the underlying topology of 3-space. Everitt (2004) has generated all homotopies for Platonic spherical 3-manifolds by face gluings. We transform the glue generators into isomorphic deck transformations. The deck transformations act on a spherical Platonic 3-manifold as prototile and tile the 3-sphere by its images. A complete set of orthonormal functions on the 3-sphere is spanned by the Wigner harmonic polynomials. For a tetrahedral, two cubic and three octahedral manifolds we construct algebraically linear combinations of Wigner polynomials, invariant under deck transformations and with domain the manifold. We prove boundary conditions on polyhedral faces from homotopy. By algebraic means we pass to a multipole expansion. Assuming random models of the CMB radiation, we derive multipole selection rules, d...
Institute of Scientific and Technical Information of China (English)
Metin Orbay; Telhat Ozdogan
2001-01-01
As an example of the use of the analytical formulas derived for electric multipole moment integrals over STOs in our previous work (I.L Guseinov,et al.,J.Mol.Struct.(Theochem) 465 (1999) 5),the 2v-pole electric moments have been calculated for the ground electronic states of LiH,BH and FH of the first-row diatomic hydride molecules. Calculated electric multipole moment values are in agreement with literatures.By the use of these analytical formulas the 2v -pole moments for multiatomic molecules can be evaluated most efficiently and accurately by employing STOs as basis sets.
Lim, Wen Xiang; Han, Song; Gupta, Manoj; MacDonald, Kevin F.; Singh, Ranjan
2017-08-01
We report on an experimental and computational (multipole decomposition) study of Fano resonance modes in complementary near-IR plasmonic metamaterials. Resonance wavelengths and linewidths can be controlled by changing the symmetry of the unit cell so as to manipulate the balance among multipole contributions. In the present case, geometrically inverting one half of a four-slot (paired asymmetric double bar) unit cell design changes the relative magnitude of magnetic quadrupole and toroidal dipole contributions leading to the enhanced quality factor, figure of merit, and spectral tuning of the plasmonic Fano resonance.
Termination shock thermal processes as a possible source for the CMB low-order multipole anomalies
2009-01-01
We discuss the possibility that the observed low-order multipole features of the cosmic microwave background radiation (CMB) all originate in the termination shock (TS) region of the heliosheath that surrounds the solar system. If the intrinsic CMB spectrum is assumed to be a pure monopole (2.73K) then thermodynamic processes occurring within the plasma region of the TS could imprint the observed power spectrum of the low-order multipoles and their alignment (the so-called "axis of evil") ont...
Directory of Open Access Journals (Sweden)
A. Schroeder
2012-09-01
Full Text Available This paper proposes a compression of far field matrices in the fast multipole method and its multilevel extension for electromagnetic problems. The compression is based on a spherical harmonic representation of radiation patterns in conjunction with a radiating mode expression of the surface current. The method is applied to study near field effects and the far field of an antenna placed on a ship surface. Furthermore, the electromagnetic scattering of an electrically large plate is investigated. It is demonstrated, that the proposed technique leads to a significant memory saving, making multipole algorithms even more efficient without compromising the accuracy.
Fast Multipole BEM for 3-D Elastostatic Problems with Applications for Thin Structures
Institute of Scientific and Technical Information of China (English)
ZHAO Libin; YAO Zhenhan
2005-01-01
The fast multipole method (FMM) has been used to reduce the computing operations and memory requirements in large numerical analysis problems. In this paper, the FMM based on Taylor expansions is combined with the boundary element method (BEM) for three-dimensional elastostatic problems to solve thin plate and shell structures. The fast multipole boundary element method (FM-BEM) requires O(N) operations and memory for problems with N unknowns. The numerical results indicate that for the analysis of thin structures, the FM-BEM is much more efficient than the conventional BEM and the accuracy achieved is sufficient for engineering applications.
Apparatus and method of dissociating ions in a multipole ion guide
Webb, Ian K.; Tang, Keqi; Smith, Richard D.; Ibrahim, Yehia M.; Anderson, Gordon A.
2014-07-08
A method of dissociating ions in a multipole ion guide is disclosed. A stream of charged ions is supplied to the ion guide. A main RF field is applied to the ion guide to confine the ions through the ion guide. An excitation RF field is applied to one pair of rods of the ion guide. The ions undergo dissociation when the applied excitation RF field is resonant with a secular frequency of the ions. The multipole ion guide is, but not limited to, a quadrupole, a hexapole, and an octopole.
Multipole Field Effects for the Superconducting Parallel-Bar Deflecting/Crabbing Cavities
Energy Technology Data Exchange (ETDEWEB)
De Silva, Payagalage Subashini Uddika [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States) and Old Dominion University, Norfolk, VA (United States); Delayen, Jean Roger [Old Dominion University, Norfolk, VA (United States)
2012-09-01
The superconducting parallel-bar deflecting/crabbing cavity is currently being considered as one of the design options in rf separation for the Jefferson Lab 12 GeV upgrade and for the crabbing cavity for the proposed LHC luminosity upgrade. Knowledge of multipole field effects is important for accurate beam dynamics study of rf structures. The multipole components can be accurately determined numerically using the electromagnetic surface field data in the rf structure. This paper discusses the detailed analysis of those components for the fundamental deflecting/crabbing mode and higher order modes in the parallel-bar deflecting/crabbing cavity.
Effects of Crab Cavities' Multipole Content in an Electron-Ion Collider
Energy Technology Data Exchange (ETDEWEB)
Satogata, Todd J. [Jefferson Lab., Newport News, VA (United States); Morozov, Vasiliy [Jefferson Lab., Newport News, VA (United States); Delayen, Jean R. [Old Dominion Univ., Norfolk, VA (United States); Jefferson Lab., Newport News, VA (United States); Castillo, Alejandro [Old Dominion Univ., Norfolk, VA (United States)
2015-09-01
The impact on the beam dynamics of the Medium Energy Electron-Ion Colider (MEIC) due to the multipole content of the 750 MHz crab cavity was studied using thin multipole elements for 6D phase space particle tracking in ELEGANT. Target values of the sextupole component for the cavity’s field expansion were used to perform preliminary studies on the proton beam stability when compared to the case of pure dipole content of the rf kicks. Finally, important effects on the beam sizes due to non-linear components of the crab cavities’ fields were identified, and some criteria for their future study were proposed.
Palmesi, Pietro; Bruckner, Florian; Abert, Claas; Suess, Dieter
2016-01-01
The long-range magnetic field is the most time-consuming part in micromagnetic simulations. Improvements both on a numerical and computational basis can relief problems related to this bottleneck. This work presents an efficient implementation of the Fast Multipole Method [FMM] for the magnetic scalar potential as used in micromagnetics. We assume linearly magnetized tetrahedral sources, treat the near field directly and use analytical integration on the multipole expansion in the far field. This approach tackles important issues like the vectorial and continuous nature of the magnetic field. By using FMM the calculations scale linearly in time and memory.
Geodynamic simulations using the fast multipole boundary element method
Drombosky, Tyler W.
Interaction between viscous fluids models two important phenomena in geophysics: (i) the evolution of partially molten rocks, and (ii) the dynamics of Ultralow-Velocity Zones. Previous attempts to numerically model these behaviors have been plagued either by poor resolution at the fluid interfaces or high computational costs. We employ the Fast Multipole Boundary Element Method, which tracks the evolution of the fluid interfaces explicitly and is scalable to large problems, to model these systems. The microstructure of partially molten rocks strongly influences the macroscopic physical properties. The fractional area of intergranular contact, contiguity, is a key parameter that controls the elastic strength of the grain network in the partially molten aggregate. We study the influence of matrix deformation on the contiguity of an aggregate by carrying out pure shear and simple shear deformations of an aggregate. We observe that the differential shortening, the normalized difference between the major and minor axes of grains is inversely related to the ratio between the principal components of the contiguity tensor. From the numerical results, we calculate the seismic anisotropy resulting from melt redistribution during pure and simple shear deformation. During deformation, the melt is expelled from tubules along three grain corners to films along grain edges. The initially isotropic fractional area of intergranular contact, contiguity, becomes anisotropic due to deformation. Consequently, the component of contiguity evaluated on the plane parallel to the axis of maximum compressive stress decreases. We demonstrate that the observed global shear wave anisotropy and shear wave speed reduction of the Lithosphere-Asthenosphere Boundary are best explained by 0.1 vol% partial melt distributed in horizontal films created by deformation. We use our microsimulation in conjunction with a large scale mantle deep Earth simulation to gain insight into the formation of
Nitadori, Keigo
2014-01-01
We propose an efficient algorithm for the evaluation of the potential and its gradient of gravitational/electrostatic $N$-body systems, which we call particle mesh multipole method (PMMM or PM$^3$). PMMM can be understood both as an extension of the particle mesh (PM) method and as an optimization of the fast multipole method (FMM).In the former viewpoint, the scalar density and potential held by a grid point are extended to multipole moments and local expansions in $(p+1)^2$ real numbers, where $p$ is the order of expansion. In the latter viewpoint, a hierarchical octree structure which brings its $\\mathcal O(N)$ nature, is replaced with a uniform mesh structure, and we exploit the convolution theorem with fast Fourier transform (FFT) to speed up the calculations. Hence, independent $(p+1)^2$ FFTs with the size equal to the number of grid points are performed. The fundamental idea is common to PPPM/MPE by Shimada et al. (1993) and FFTM by Ong et al. (2003). PMMM differs from them in supporting both the open ...
Computational Study of Plasma Response to a Variable Electric Multipole Configuration
Hicks, Nathaniel
2016-10-01
A computational study is presented of the behavior of a low temperature, quasi-neutral plasma in a three-dimensional, time-varying electric multipole field. A 3-D particle- in-cell (PIC) plasma code is used to simulate the process. The simulations study the effect of the plasma species' mass difference on the plasma response, with the multipole field frequency being chosen, for example, to interact strongly with light particles but negligibly with heavy ones. The effect of focusing the light species to the center of the multipole structure is examined, with space charge neutralized by the presence of the heavy species. The dependence of plasma density on driving field parameters and geometry (order of multipole, shape of equipotential surfaces) is studied, as well as the behavior of the plasma near gyroresonance in the presence of a background magnetic field. The formation and dependences of the RF plasma sheath are studied, as the sheath responds to variation of the plasma and external field characteristics. The results of the computer modeling study are to inform an initial experimental design and study of the same effects. Supported by NSF/DOE Partnership in Basic Plasma Physics and Engineering Award PHY-1619615.
Identifying the Development in Phase and Amplitude of Dipole and Multipole Radiation
Rice, E. M.; Bradshaw, D. S.; Saadi, K.; Andrews, D. L.
2012-01-01
The spatial variation in phase and the propagating wave-front of plane wave electromagnetic radiation are widely familiar text-book territory. In contrast, the developing amplitude and phase of radiation emitted by a dipole or multipole source generally receive less attention, despite the prevalence of these systems. There is additional complexity…
Cumulate Fragments in Silicic Ignimbrites
Bachmann, O.; Ellis, B. S.; Wolff, J.
2014-12-01
Increasingly, studies are concluding that silicic ignimbrites are the result of the amalgamation of multiple discrete magma batches. Yet the existence of discrete batches presents a conundrum for magma generation and storage; if silicic magma batches are not generated nearly in situ in the upper crust, they must traverse, and reside within, a thermally hostile environment with large temperature gradients, resulting in low survivability in their shallow magmatic hearths. The Snake River Plain (Idaho, USA) is a type example of this 'multi-batch' assembly with ignimbrites containing multiple populations of pyroxene crystals, glass shards, and crystal aggregates. The ubiquitous crystal aggregates hint at a mechanism to facilitate the existence of multiple, relatively small batches of rhyolite in the upper crust. These aggregates contain the same plagioclase, pyroxene, and oxide mineral compositions as single phenocrysts of the same minerals in their host rocks, but they have significantly less silicic bulk compositions and lack quartz and sanidine, which occur as single phenocrysts in the deposits. This implies significant crystallization followed by melt extraction from mushy reservoir margins. The extracted melt then continues to evolve (crystallizing sanidine and quartz) while the melt-depleted margins provide an increasingly rigid and refractory network segregating the crystal-poor batches of magma. The hot, refractory, margins insulate the crystal-poor lenses, allowing (1) extended residence in the upper crust, and (2) preservation of chemical heterogeneities among batches. In contrast, systems that produce cumulates richer in low-temperature phases (quartz, K-feldspars, and/or biotite) favour remelting upon recharge, leading to less segregation of eruptible melt pockets and the formation of gradationally zoned ignimbrites. The occurrence of similar crystal aggregates from a variety of magmatic lineages suggests the generality of this process.
Production of high-PT cumulative particles in proton-nuclear interactions at 50 GeV
Ammosov, V V; Viktorov, V A; Gapienko, V A; Gapienko, G S; Gres, V N; Korotkov, V A; Mysnik, A I; Prudkoglyad, A F; Sviridov, Yu M; Semak, A A; Terekhov, V I; Uglekov, V Ya; Ukhanov, M N; Chuiko, B V; Baldin, A A; Shimanskiy, S S
2014-01-01
The data on production of cumulative particles in the high transverse momenta domain (up to ~ 3.5 GeV/c) in proton-nuclear interactions are presented for the first time. An indication on the local character of particle production in the cumulative domain is obtained. The observed strong dependence of the particle production cross section on the atomic mass of the target does not fit the A - dependence obtained in the pre-cumulative and cumulative domains for low transverse momenta at constant part of the exponent. The experiment was performed at U70 (IHEP) with the extracted 50 GeV/c proton beam.
Lin, Dejun
2015-01-01
Accurate representation of intermolecular forces has been the central task of classical atomic simulations, known as molecular mechanics. Recent advancements in molecular mechanics models have put forward the explicit representation of permanent and/or induced electric multipole (EMP) moments. The formulas developed so far to calculate EMP interactions tend to have complicated expressions, especially in Cartesian coordinates, which can only be applied to a specific kernel potential function. For example, one needs to develop a new formula each time a new kernel function is encountered. The complication of these formalisms arises from an intriguing and yet obscured mathematical relation between the kernel functions and the gradient operators. Here, I uncover this relation via rigorous derivation and find that the formula to calculate EMP interactions is basically invariant to the potential kernel functions as long as they are of the form f(r), i.e., any Green’s function that depends on inter-particle distance. I provide an algorithm for efficient evaluation of EMP interaction energies, forces, and torques for any kernel f(r) up to any arbitrary rank of EMP moments in Cartesian coordinates. The working equations of this algorithm are essentially the same for any kernel f(r). Recently, a few recursive algorithms were proposed to calculate EMP interactions. Depending on the kernel functions, the algorithm here is about 4–16 times faster than these algorithms in terms of the required number of floating point operations and is much more memory efficient. I show that it is even faster than a theoretically ideal recursion scheme, i.e., one that requires 1 floating point multiplication and 1 addition per recursion step. This algorithm has a compact vector-based expression that is optimal for computer programming. The Cartesian nature of this algorithm makes it fit easily into modern molecular simulation packages as compared with spherical coordinate-based algorithms. A
Energy Technology Data Exchange (ETDEWEB)
Lin, Dejun, E-mail: dejun.lin@gmail.com [Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York 14642 (United States)
2015-09-21
Accurate representation of intermolecular forces has been the central task of classical atomic simulations, known as molecular mechanics. Recent advancements in molecular mechanics models have put forward the explicit representation of permanent and/or induced electric multipole (EMP) moments. The formulas developed so far to calculate EMP interactions tend to have complicated expressions, especially in Cartesian coordinates, which can only be applied to a specific kernel potential function. For example, one needs to develop a new formula each time a new kernel function is encountered. The complication of these formalisms arises from an intriguing and yet obscured mathematical relation between the kernel functions and the gradient operators. Here, I uncover this relation via rigorous derivation and find that the formula to calculate EMP interactions is basically invariant to the potential kernel functions as long as they are of the form f(r), i.e., any Green’s function that depends on inter-particle distance. I provide an algorithm for efficient evaluation of EMP interaction energies, forces, and torques for any kernel f(r) up to any arbitrary rank of EMP moments in Cartesian coordinates. The working equations of this algorithm are essentially the same for any kernel f(r). Recently, a few recursive algorithms were proposed to calculate EMP interactions. Depending on the kernel functions, the algorithm here is about 4–16 times faster than these algorithms in terms of the required number of floating point operations and is much more memory efficient. I show that it is even faster than a theoretically ideal recursion scheme, i.e., one that requires 1 floating point multiplication and 1 addition per recursion step. This algorithm has a compact vector-based expression that is optimal for computer programming. The Cartesian nature of this algorithm makes it fit easily into modern molecular simulation packages as compared with spherical coordinate-based algorithms. A
Liu, Yangfan; Bolton, J Stuart
2016-08-01
The (Cartesian) multipole series, i.e., the series comprising monopole, dipoles, quadrupoles, etc., can be used, as an alternative to the spherical or cylindrical wave series, in representing sound fields in a wide range of problems, such as source radiation, sound scattering, etc. The proofs of the completeness of the spherical and cylindrical wave series in these problems are classical results, and it is also generally agreed that the Cartesian multipole series spans the same space as the spherical waves: a rigorous mathematical proof of that statement has, however, not been presented. In the present work, such a proof of the completeness of the Cartesian multipole series, both in two and three dimensions, is given, and the linear dependence relations among different orders of multipoles are discussed, which then allows one to easily extract a basis from the multipole series. In particular, it is concluded that the multipoles comprising the two highest orders in the series form a basis of the whole series, since the multipoles of all the lower source orders can be expressed as a linear combination of that basis.
Beu, Steven C; Hendrickson, Christopher L; Marshall, Alan G
2011-03-01
Radiofrequency (rf) multipole ion guides are widely used to transfer ions through the strong magnetic field gradient between source and analyzer regions of external source Fourier transform ion cyclotron resonance mass spectrometers. Although ion transfer as determined solely by the electric field in a multipole ion guide has been thoroughly studied, transfer influenced by immersion in a strong magnetic field gradient has not been as well characterized. Recent work has indicated that the added magnetic field can have profound effects on ion transfer, ultimately resulting in loss of ions initially contained within the multipole. Those losses result from radial ejection of ions due to transient cyclotron resonance that occurs when ions traverse a region in which the magnetic field results in an effective cyclotron frequency equal to the multipole rf drive frequency divided by the multipole order (multipole order is equal to one-half the number of poles). In this work, we describe the analytical basis for ion resonance in a rf multipole ion guide with superposed static magnetic field and compare with results of numerical trajectory simulations. © American Society for Mass Spectrometry, 2011
Cumulative human impacts on marine predators
DEFF Research Database (Denmark)
Maxwell, Sara M; Hazen, Elliott L; Bograd, Steven J
2013-01-01
Stressors associated with human activities interact in complex ways to affect marine ecosystems, yet we lack spatially explicit assessments of cumulative impacts on ecologically and economically key components such as marine predators. Here we develop a metric of cumulative utilization and impact...
Selective addressing of high-rank atomic polarization moments
Yashchuk, V V; Gawlik, W; Kimball, D F; Malakyan, Y P; Rochester, S M; Malakyan, Yu. P.
2003-01-01
We describe a method of selective generation and study of polarization moments of up to the highest rank $\\kappa=2F$ possible for a quantum state with total angular momentum $F$. The technique is based on nonlinear magneto-optical rotation with frequency-modulated light. Various polarization moments are distinguished by the periodicity of light-polarization rotation induced by the atoms during Larmor precession and exhibit distinct light-intensity and frequency dependences. We apply the method to study polarization moments of $^{87}$Rb atoms contained in a vapor cell with antirelaxation coating. Distinct ultra-narrow (1-Hz wide) resonances, corresponding to different multipoles, appear in the magnetic-field dependence of the optical rotation. The use of the highest-multipole resonances has important applications in quantum and nonlinear optics and in magnetometry.
Antimatter Plasmas in a Multipole Trap for Antihydrogen
Andresen, G B; Boston, A; Bowe, P D; Cesar, C L; Chapman, S; Charlton, M; Chartier, M; Deutsch, A; Fajans, J; Fujiwara, M C; Funakoshi, R; Gill, D R; Gomberoff, K; Hangst, J S; Hayano, R S; Hydomako, R; Jenkins, M J; Jørgensen, L V; Kurchaninov, L; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Robicheaux, F; Sarid, E; Silveira, D M; Storey, J W; Telle, H H; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y
2007-01-01
We have demonstrated storage of plasmas of the charged constituents of the antihydrogen atom, antiprotons and positrons, in a Penning trap surrounded by a minimum-B magnetic trap designed for holding neutral antiatoms. The neutral trap comprises a superconducting octupole and two superconducting, solenoidal mirror coils. We have measured the storage lifetimes of antiproton and positron plasmas in the combined Penning-neutral trap, and compared these to lifetimes without the neutral trap fields. The magnetic well depth was 0.6 T, deep enough to trap ground state antihydrogen atoms of up to about 0.4 K in temperature. We have demonstrated that both particle species can be stored for times long enough to permit antihydrogen production and trapping studies.
Dispersion forces at arbitrary distances. [between closed-shell atoms
Jacobi, N.; Csanak, G.
1975-01-01
The formalism of Boehm and Yaris is used to evaluate explicitly the leading term of the London dispersion force between closed-shell atoms. Instead of using the usual multipole expansion, which breaks down at intermediate internuclear distances, an analytic representation of the Born amplitude together with a general angular momentum analysis is used. As a result, expressions are obtained which reduce to the usual dispersion forces at large distances and are finite at all distances.
Forbidden atomic transitions driven by an intensity-modulated laser trap.
Moore, Kaitlin R; Anderson, Sarah E; Raithel, Georg
2015-01-20
Spectroscopy is an essential tool in understanding and manipulating quantum systems, such as atoms and molecules. The model describing spectroscopy includes the multipole-field interaction, which leads to established spectroscopic selection rules, and an interaction that is quadratic in the field, which is not often employed. However, spectroscopy using the quadratic (ponderomotive) interaction promises two significant advantages over spectroscopy using the multipole-field interaction: flexible transition rules and vastly improved spatial addressability of the quantum system. Here we demonstrate ponderomotive spectroscopy by using optical-lattice-trapped Rydberg atoms, pulsating the lattice light and driving a microwave atomic transition that would otherwise be forbidden by established spectroscopic selection rules. This ability to measure frequencies of previously inaccessible transitions makes possible improved determinations of atomic characteristics and constants underlying physics. The spatial resolution of ponderomotive spectroscopy is orders of magnitude better than the transition frequency would suggest, promising single-site addressability in dense particle arrays for quantum computing applications.
Forbidden atomic transitions driven by an intensity-modulated laser trap
Moore, Kaitlin R; Raithel, Georg
2014-01-01
Spectroscopy is an essential tool in understanding and manipulating quantum systems, such as atoms and molecules. The model describing spectroscopy includes a multipole-field interaction, which leads to established spectroscopic selection rules, and an interaction that is quadratic in the field, which is often neglected. However, spectroscopy using the quadratic (ponderomotive) interaction promises two significant advantages over spectroscopy using the multipole-field interaction: flexible transition rules and vastly improved spatial addressability of the quantum system. For the first time, we demonstrate ponderomotive spectroscopy by using optical-lattice-trapped Rydberg atoms, pulsating the lattice light at a microwave frequency, and driving a microwave atomic transition that would otherwise be forbidden by established spectroscopic selection rules. This new ability to measure frequencies of previously inaccessible transitions makes possible improved determinations of atomic characteristics and constants un...
Nonlinear cumulative damage model for multiaxial fatigue
Institute of Scientific and Technical Information of China (English)
SHANG De-guang; SUN Guo-qin; DENG Jing; YAN Chu-liang
2006-01-01
On the basis of the continuum fatigue damage theory,a nonlinear uniaxial fatigue cumulative damage model is first proposed.In order to describe multiaxial fatigue damage characteristics,a nonlinear multiaxial fatigue cumulative damage model is developed based on the critical plane approach,The proposed model can consider the multiaxial fatigue limit,mean hydrostatic pressure and the unseparated characteristic for the damage variables and loading parameters.The recurrence formula of fatigue damage model was derived under multilevel loading,which is used to predict multiaxial fatigue life.The results showed that the proposed nonlinear multiaxial fatigue cumulative damage model is better than Miner's rule.
Reply to Comment on 'On the origin dependence of multipole moments in electromagnetism'
Energy Technology Data Exchange (ETDEWEB)
De Visschere, Patrick [UGent, ELIS, Sint-Pietersnieuwstraat 41, B-9000 Gent (Belgium)
2010-12-22
In this reply, we emphasize that the goal of our original paper was to show that a straightforward application of standard multipole theory does not lead to unphysical results as claimed by Raab and de Lange. We stress once more that an origin shift for calculating the multipoles must be accompanied by a relocation of these multipoles, which compensates the effects of the origin dependence of the multipoles. We point out that the position of the macroscopic boundary is a relevant parameter. We agree that the transformation proposed by Raab and de Lange could still be useful supposing it only affects the phase of the reflected/trasmitted waves. We dispute that the transformation as derived by Raab and de Lange is unique. (reply)
Cumulative cultural learning: Development and diversity.
Legare, Cristine H
2017-07-24
The complexity and variability of human culture is unmatched by any other species. Humans live in culturally constructed niches filled with artifacts, skills, beliefs, and practices that have been inherited, accumulated, and modified over generations. A causal account of the complexity of human culture must explain its distinguishing characteristics: It is cumulative and highly variable within and across populations. I propose that the psychological adaptations supporting cumulative cultural transmission are universal but are sufficiently flexible to support the acquisition of highly variable behavioral repertoires. This paper describes variation in the transmission practices (teaching) and acquisition strategies (imitation) that support cumulative cultural learning in childhood. Examining flexibility and variation in caregiver socialization and children's learning extends our understanding of evolution in living systems by providing insight into the psychological foundations of cumulative cultural transmission-the cornerstone of human cultural diversity.
Goussev, Arseni; Schubert, Roman; Waalkens, Holger; Wiggins, Stephen
2009-01-01
The quantum normal form approach to quantum transition state theory is used to compute the cumulative reaction probability for collinear exchange reactions. It is shown that for heavy-atom systems such as the nitrogen-exchange reaction, the quantum normal form approach gives excellent results and
Calculating Cumulative Binomial-Distribution Probabilities
Scheuer, Ernest M.; Bowerman, Paul N.
1989-01-01
Cumulative-binomial computer program, CUMBIN, one of set of three programs, calculates cumulative binomial probability distributions for arbitrary inputs. CUMBIN, NEWTONP (NPO-17556), and CROSSER (NPO-17557), used independently of one another. Reliabilities and availabilities of k-out-of-n systems analyzed. Used by statisticians and users of statistical procedures, test planners, designers, and numerical analysts. Used for calculations of reliability and availability. Program written in C.
The fast multipole method and point dipole moment polarizable force fields
Coles, Jonathan P.; Masella, Michel
2015-01-01
We present an implementation of the fast multipole method for computing Coulombic electrostatic and polarization forces from polarizable force-fields based on induced point dipole moments. We demonstrate the expected O(N) scaling of that approach by performing single energy point calculations on hexamer protein subunits of the mature HIV-1 capsid. We also show the long time energy conservation in molecular dynamics at the nanosecond scale by performing simulations of a protein complex embedded in a coarse-grained solvent using a standard integrator and a multiple time step integrator. Our tests show the applicability of fast multipole method combined with state-of-the-art chemical models in molecular dynamical systems.
Hierarchy of Universal Relations for Neutron Stars in Terms of Multipole Moments
Manko, V S
2016-01-01
Recent studies of the analytical and numerical models of neutron stars strongly suggest that their exterior field can be described by only four arbitrary parameters of the 2-soliton solution of Einstein's equations. Assuming that this is the case, we show that there exists an infinite hierarchy of the universal relations for neutron stars in terms of multipole moments that arises as a series of the degeneration conditions for generic soliton solutions. The simplest of these relations yields a correct expression for the mass-hexadecapole moment as a function of the angular momentum, revealing a need for a more precise definition of this and higher multipole moments in the numerical models of neutron stars.
Termination shock thermal processes as a possible source for the CMB low-order multipole anomalies
Sharpe, H N
2009-01-01
We discuss the possibility that the observed low-order multipole features of the cosmic microwave background radiation (CMB) all originate in the termination shock (TS) region of the heliosheath that surrounds the solar system. If the intrinsic CMB spectrum is assumed to be a pure monopole (2.73K) then thermodynamic processes occurring within the plasma region of the TS could imprint the observed power spectrum of the low-order multipoles and their alignment (the so-called "axis of evil") onto this background isotropic CMB. Conditions are outlined for the geometric shape of the TS region. A key requirement of this model is that the TS plasma be characterized as an optically thin graybody with non-LTE perturbations. Data from the ongoing Voyager missions is critical to this study.
Method of reducing multipole content in a conductor assembly during manufacture
Energy Technology Data Exchange (ETDEWEB)
Meinke, Rainer
2016-05-24
A method for manufacture of a conductor assembly. The assembly is of the type which, when conducting current, generates a magnetic field or in which, in the presence of a changing magnetic field, a voltage is induced. In an example embodiment one or more first coil rows are formed. The assembly has multiple coil rows about an axis with outer coil rows formed about inner coil rows. A determination is made of deviations from specifications associated with the formed one or more first coil rows. One or more deviations correspond to a magnitude of a multipole field component which departs from a field specification. Based on the deviations, one or more wiring patterns are generated for one or more second coil rows to be formed about the one or more first coil rows. The one or more second coil rows are formed in the assembly. The magnitude of each multipole field component that departs from the field specification is offset.
Efficient evaluation of antenna fields by a time-domain multipole analysis
Directory of Open Access Journals (Sweden)
J. Adam
2009-05-01
Full Text Available The contribution describes a systematic method to efficiently determine frequency-domain electromagnetic antenna fields and characteristics for a broad spectrum via a single time-domain (e.g., Finite-Difference Time-Domain, FDTD calculation. From a time-domain simulation of an antenna driven by a wide-band signal, a single modified Fourier transformation yields the frequency-domain multipole amplitudes. The corresponding multipole expansions are valid for the entire spectrum of the input pulse and at any point outside a minimum sphere enclosing the antenna. This allows a computationally cheap and elegant post-processing of arbitrary antenna characteristics. As an example of use the method is applied to determine high-resolution three-dimensional radiation patterns of an antipodal Vivaldi antenna.
Local geometry of electromagnetic fields and its role in molecular multipole transitions
Yang, Nan
2010-01-01
Electromagnetic fields with complex spatial variation routinely arise in Nature. We study the response of a small molecule to monochromatic fields of arbitrary three-dimensional geometry. First, we consider the allowed configurations of the fields and field gradients at a single point in space. Many configurations cannot be generated from a single plane wave, regardless of polarization, but any allowed configuration can be generated by superposition of multiple plane waves. There is no local configuration of the fields and gradients that requires near-field effects. Second, we derive a set of local electromagnetic quantities, where each couples to a particular multipole transition. These quantities are small or zero in plane waves, but can be large in regions of certain superpositions of plane waves. Our findings provide a systematic framework for designing far-field and near-field experiments to drive multipole transitions. The proposed experiments provide information on molecular structure that is inaccessi...
Rapid modelling of the redshift-space power spectrum multipoles for a masked density field
Wilson, M. J.; Peacock, J. A.; Taylor, A. N.; de la Torre, S.
2017-01-01
In this work, we reformulate the forward modelling of the redshift-space power spectrum multipole moments for a masked density field, as encountered in galaxy redshift surveys. Exploiting the symmetries of the redshift-space correlation function, we provide a masked-field generalization of the Hankel transform relation between the multipole moments in real and Fourier space. Using this result, we detail how a likelihood analysis requiring computation for a broad range of desired P(k) models may be executed 103-104 times faster than with other common approaches, together with significant gains in spectral resolution. We present a concrete application to the complex angular geometry of the VIMOS Public Extragalactic Redshift Survey PDR-1 release and discuss the validity of this technique for finite-angle surveys.
FRICTIONAL CONTACT MULTIPOLE-BEM AND 3-D ANALYSIS OF SCREWPAIRS
Institute of Scientific and Technical Information of China (English)
Chen Xiumin; Shen Guangxian; Liu Deyi
2004-01-01
The 3-D traction field in the pressure screw-pair of a 3 500 heavy and medium plate mill press down system is successfully calculated by applying the 3-D frictional contact multipole-BEM and the corresponding program that has been developed. The computing results show the medium diameter orientation is unreliable, especially under the interference of an outer force couple. Under such working conditions, the circumferential traction distribution on the screw teeth is extremely uneven, which is the main reason for the destruction and short life time of screw-pairs. When utilizing the same precision (the relative tolerance is 10×10-5),the mltipole-BEM uses almost the CPU time as used by the FEM,but the needed computer menory size is only one eighieth of that needed by the FEM(10 MB vs.800 MB).The multipole-BEM is well suited for computing large-scale engineering problems.
Cumulative cultural evolution: the role of teaching.
Castro, Laureano; Toro, Miguel A
2014-04-21
In humans, cultural transmission occurs usually by cumulative inheritance, generating complex adaptive behavioral features. Cumulative culture requires key psychological processes (fundamentally imitation and teaching) that are absent or impoverished in non-human primates. In this paper we analyze the role that teaching has played in human cumulative cultural evolution. We assume that a system of cumulative culture generates increasingly adaptive behaviors, that are also more complex and difficult to imitate. Our thesis is that, as cultural traits become more complex, cumulative cultural transmission requires teaching to ensure accurate transmission from one generation to the next. In an increasingly complex cultural environment, we consider that individuals commit errors in imitation. We develop a model of cumulative cultural evolution in a changing environment and show that these errors hamper the process of cultural accumulation. We also show that a system of teaching between parents and offspring that increases the fidelity of imitation unblocks the accumulation and becomes adaptive whenever the gain in fitness compensates the cost of teaching.
Human cumulative culture: a comparative perspective.
Dean, Lewis G; Vale, Gill L; Laland, Kevin N; Flynn, Emma; Kendal, Rachel L
2014-05-01
Many animals exhibit social learning and behavioural traditions, but human culture exhibits unparalleled complexity and diversity, and is unambiguously cumulative in character. These similarities and differences have spawned a debate over whether animal traditions and human culture are reliant on homologous or analogous psychological processes. Human cumulative culture combines high-fidelity transmission of cultural knowledge with beneficial modifications to generate a 'ratcheting' in technological complexity, leading to the development of traits far more complex than one individual could invent alone. Claims have been made for cumulative culture in several species of animals, including chimpanzees, orangutans and New Caledonian crows, but these remain contentious. Whilst initial work on the topic of cumulative culture was largely theoretical, employing mathematical methods developed by population biologists, in recent years researchers from a wide range of disciplines, including psychology, biology, economics, biological anthropology, linguistics and archaeology, have turned their attention to the experimental investigation of cumulative culture. We review this literature, highlighting advances made in understanding the underlying processes of cumulative culture and emphasising areas of agreement and disagreement amongst investigators in separate fields.
Multipoles of Even/Odd Split-Ring Resonators
Directory of Open Access Journals (Sweden)
Andrew Chen
2015-08-01
Full Text Available The ultimate goal of metamaterial engineering is to have complete control over the electromagnetic constitutive parameters in three-dimensional space. This engineering can be done by considering either single meta-atoms or full meta-arrays. We follow the first route and perform numerical simulations of split-ring resonators, with different gap numbers and under varying illumination scenarios, to investigate their individual multipolar scattering response. For the fundamental resonance, we observe that odd-gap rings always exhibit overlapping electric and magnetic dipole responses while even-gap rings only exhibit that behavior accidentally. We expect our results to foster progress in the engineering of three-dimensional disordered metamaterials.
Multipole plasmons and their disappearance in few-nanometre silver nanoparticles
DEFF Research Database (Denmark)
Raza, Søren; Kadkhodazadeh, Shima; Christensen, Thomas
2015-01-01
Electron energy-loss spectroscopy can be used for detailed spatial and spectral characterization of optical excitations in metal nanoparticles. In previous electron energy-loss experiments on silver nanoparticles with radii smaller than 20 nm, only the dipolar surface plasmon resonance was assumed...... theoretical predictions. Unlike in optical spectra, multipole surface plasmons are important in electron energy-loss spectra even of ultrasmall metallic nanoparticles....
Burt, E. A.; Taghavi-Larigani, S.; Prestage, J. D.; Tjoelker, R. L.
2009-04-01
We have developed a compensated multi-pole Linear Ion Trap Standard (LITS) that eliminates nearly all frequency sensitivity to residual ion number variations. When operated with 199Hg+, this trapped ion clock has recently demonstrated extremely good stability over a 9-month period. The short-term stability has been measured at 5 × 10-14/τ1/2 and an upper limit on long-term fractional frequency deviations of REFID="9789812838223_0037FN001">
Ergul, Ozgur
2014-01-01
The Multilevel Fast Multipole Algorithm (MLFMA) for Solving Large-Scale Computational Electromagnetic Problems provides a detailed and instructional overview of implementing MLFMA. The book: Presents a comprehensive treatment of the MLFMA algorithm, including basic linear algebra concepts, recent developments on the parallel computation, and a number of application examplesCovers solutions of electromagnetic problems involving dielectric objects and perfectly-conducting objectsDiscusses applications including scattering from airborne targets, scattering from red
Energy Technology Data Exchange (ETDEWEB)
White, J.; Phillips, J.R.; Korsmeyer, T. [Massachusetts Institute of Technology, Cambridge, MA (United States)
1994-12-31
Mixed first- and second-kind surface integral equations with (1/r) and {partial_derivative}/{partial_derivative} (1/r) kernels are generated by a variety of three-dimensional engineering problems. For such problems, Nystroem type algorithms can not be used directly, but an expansion for the unknown, rather than for the entire integrand, can be assumed and the product of the singular kernal and the unknown integrated analytically. Combining such an approach with a Galerkin or collocation scheme for computing the expansion coefficients is a general approach, but generates dense matrix problems. Recently developed fast algorithms for solving these dense matrix problems have been based on multipole-accelerated iterative methods, in which the fast multipole algorithm is used to rapidly compute the matrix-vector products in a Krylov-subspace based iterative method. Another approach to rapidly computing the dense matrix-vector products associated with discretized integral equations follows more along the lines of a multigrid algorithm, and involves projecting the surface unknowns onto a regular grid, then computing using the grid, and finally interpolating the results from the regular grid back to the surfaces. Here, the authors describe a precorrectted-FFT approach which can replace the fast multipole algorithm for accelerating the dense matrix-vector product associated with discretized potential integral equations. The precorrected-FFT method, described below, is an order n log(n) algorithm, and is asymptotically slower than the order n fast multipole algorithm. However, initial experimental results indicate the method may have a significant constant factor advantage for a variety of engineering problems.
High-order multipole radiation from quantum Hall states in Dirac materials
Gullans, Michael J.; Taylor, Jacob M.; Imamoǧlu, Ataç; Ghaemi, Pouyan; Hafezi, Mohammad
2017-06-01
We investigate the optical response of strongly disordered quantum Hall states in two-dimensional Dirac materials and find qualitatively different effects in the radiation properties of the bulk versus the edge. We show that the far-field radiation from the edge is characterized by large multipole moments (>50 ) due to the efficient transfer of angular momentum from the electrons into the scattered light. The maximum multipole transition moment is a direct measure of the coherence length of the edge states. Accessing these multipole transitions would provide new tools for optical spectroscopy and control of quantum Hall edge states. On the other hand, the far-field radiation from the bulk appears as random dipole emission with spectral properties that vary with the local disorder potential. We determine the conditions under which this bulk radiation can be used to image the disorder landscape. Such optical measurements can probe submicron-length scales over large areas and provide complementary information to scanning probe techniques. Spatially resolving this bulk radiation would serve as a novel probe of the percolation transition near half filling.
A Dialogue of Multipoles: Matched Asymptotic Expansion for Caged Black Holes
Gorbonos, Dan; Gorbonos, Dan; Kol, Barak
2004-01-01
No analytic solution is known to date for a black hole in a compact dimension. We develop an analytic perturbation theory where the small parameter is the size of the black hole relative to the size of the compact dimension. We set up a general procedure for an arbitrary order in the perturbation series based on an asymptotic matched expansion between two coordinate patches: the near horizon zone and the asymptotic zone. The procedure is ordinary perturbation expansion in each zone, where additionally some boundary data comes from the other zone, and so the procedure alternates between the zones. It can be viewed as a dialogue of multipoles where the black hole changes its shape (mass multipoles) in response to the field (multipoles) created by its periodic "mirrors", and that in turn changes its field and so on. We present the leading correction to the full metric including the first correction to the area-temperature relation, the leading term for black hole eccentricity and the "Archimedes effect". The nex...
A Dialogue of Multipoles: Matched Asymptotic Expansion for Caged Black Holes
Gorbonos, Dan; Kol, Barak
2004-06-01
No analytic solution is known to date for a black hole in a compact dimension. We develop an analytic perturbation theory where the small parameter is the size of the black hole relative to the size of the compact dimension. We set up a general procedure for an arbitrary order in the perturbation series based on an asymptotic matched expansion between two coordinate patches: the near horizon zone and the asymptotic zone. The procedure is ordinary perturbation expansion in each zone, where additionally some boundary data comes from the other zone, and so the procedure alternates between the zones. It can be viewed as a dialogue of multipoles where the black hole changes its shape (mass multipoles) in response to the field (multipoles) created by its periodic ``mirrors'', and that in turn changes its field and so on. We present the leading correction to the full metric including the first correction to the area-temperature relation, the leading term for black hole eccentricity and the ``Archimedes effect''. The next order corrections will appear in a sequel. On the way we determine independently the static perturbations of the Schwarzschild black hole in dimension d geq 5, where the system of equations can be reduced to ``a master equation'' — a single ordinary differential equation. The solutions are hypergeometric functions which in some cases reduce to polynomials.
Application of EEG multipole model in the diagnosis of Alzheimer's disease
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
In order to find the electroencephalogram (EEG) characteristic parameters typical of Alzheimer's disease (AD) and explore an effective diagnostic method, a new mobile current multipole model was proposed to simulate the AD patient's cortical dipole source activities.The indicators of goodness of fit (GOF) and DtononD (DD) were calculated from EEG samples to evaluate the performance of this model. Relevant results showed that this multipole model with higher GOF values and larger DD change well fitted the pathological electrical activities of cortical neurons aroused by AD's extended sulcus and gyrus in the cerebral cortex. Meanwhile, the products of DD mean & standard variance were found in a clear linear correlation with the diagnostic data of mini-mental state examination (MMSE) used in AD clinics. Furthermore, by tracing this multipole model's indicators in typical patients and contrasting with the functional magnetic resonance image (fMRI) as AD progressed, we suggested that the DD index may be suitable for monitoring the AD developments as a new diagnostic parameter.
Analysis of grain boundary dynamics using event detection and cumulative averaging
Energy Technology Data Exchange (ETDEWEB)
Gautam, A.; Ophus, C. [National Center for Electron Microscopy, LBNL, Berkeley, CA 94720 (United States); Lançon, F. [Laboratoire de Simulation Atomistique L-Sim, SP2M, INAC, CEA, 38054 Grenoble (France); Denes, P. [National Center for Electron Microscopy, LBNL, Berkeley, CA 94720 (United States); Dahmen, U., E-mail: udahmen@lbl.gov [National Center for Electron Microscopy, LBNL, Berkeley, CA 94720 (United States)
2015-04-15
To analyze extended time series of high resolution images, we have employed automated frame-by-frame comparisons that are able to detect dynamic changes in the structure of a grain boundary in Au. Using cumulative averaging of images between events allowed high resolution measurements of the atomic relaxation in the interface with sufficient accuracy for comparison with atomistic models. Cumulative averaging was also used to observe the structural rearrangement of atomic columns at a moving step in the grain boundary. The technique of analyzing changing features in high resolution images by averaging between incidents can be used to deconvolute stochastic events that occur at random intervals and on time scales well beyond that accessible to single-shot imaging. - Highlights: • We have observed dynamic structural changes in extended time series of atomic resolution images. • Application of edge detection in the time domain isolates stochastic events in dynamic observations. • Splitting time series at stochastic events highlights changes in local atomic structure. • Cumulative averaging between events generates precise atomic resolution structural images.
Predicting Cumulative Incidence Probability by Direct Binomial Regression
DEFF Research Database (Denmark)
Scheike, Thomas H.; Zhang, Mei-Jie
Binomial modelling; cumulative incidence probability; cause-specific hazards; subdistribution hazard......Binomial modelling; cumulative incidence probability; cause-specific hazards; subdistribution hazard...
Couch, Sean M.; Graziani, Carlo; Flocke, Norbert
2013-12-01
Self-gravity computation by multipole expansion is a common approach in problems such as core-collapse and Type Ia supernovae, where single large condensations of mass must be treated. The standard formulation of multipole self-gravity in arbitrary coordinate systems suffers from two significant sources of error, which we correct in the formulation presented in this article. The first source of error is due to the numerical approximation that effectively places grid cell mass at the central point of the cell, then computes the gravitational potential at that point, resulting in a convergence failure of the multipole expansion. We describe a new scheme that avoids this problem by computing gravitational potential at cell faces. The second source of error is due to sub-optimal choice of location for the expansion center, which results in angular power at high multipole l values in the gravitational field, requiring a high—and expensive—value of multipole cutoff l max. By introducing a global measure of angular power in the gravitational field, we show that the optimal coordinate for the expansion is the square-density-weighted mean location. We subject our new multipole self-gravity algorithm, implemented in the FLASH simulation framework, to two rigorous test problems: MacLaurin spheroids for which exact analytic solutions are known, and core-collapse supernovae. We show that key observables of the core-collapse simulations, particularly shock expansion, proto-neutron star motion, and momentum conservation, are extremely sensitive to the accuracy of the multipole gravity, and the accuracy of their computation is greatly improved by our reformulated solver.
Vale, G. L.; Flynn, E. G.; Kendal, R. L.
2012-01-01
Cumulative culture denotes the, arguably, human capacity to build on the cultural behaviors of one's predecessors, allowing increases in cultural complexity to occur such that many of our cultural artifacts, products and technologies have progressed beyond what a single individual could invent alone. This process of cumulative cultural evolution…
Beyond Schiff Moment: Atomic EDMs from Two-Photon Exchange
Inoue, Satoru; Ramsey-Musolf, Michael
2016-09-01
Interpretation of atomic EDM searches requires careful consideration of the Schiff theorem, which states that a neutral system of non-relativistic point charges interacting only electrostatically has zero net EDM. Atomic EDMs arise from breakdowns in the assumptions to the Schiff theorem. Conventionally, the leading contributions to EDMs of diamagnetic atoms are thought to be nuclear Schiff moments, which arise due to finite sizes of nuclei. We revisit the argument to derive the Schiff moment contribution to atomic EDMs and find that atomic EDMs can be generated from non-electrostatic interactions, namely 2 successive electron-nucleus interactions involving transverse electric multipoles. We estimate that this contribution can be comparable to the Schiff moment effect.
Couch, Sean M; Flocke, Norbert
2013-01-01
Self-gravity computation by multipole expansion is a common approach in problems such as core-collapse and Type Ia supernovae, where single large condensations of mass must be treated. The standard formulation of multipole self-gravity suffers from two significant sources of error, which we correct in the formulation presented in this article. The first source of error is due to the numerical approximation that effectively places grid cell mass at the central point of the cell, then computes the gravitational potential at that point, resulting in a convergence failure of the multipole expansion. We describe a new scheme that avoids this problem by computing gravitational potential at cell faces. The second source of error is due to sub-optimal choice of location for the expansion center, which results in angular power at high multipole $l$ values in the gravitational field, requiring a high --- and expensive --- value of multipole cutoff \\lmax. By introducing a global measure of angular power in the gravitati...
Is cumulated pyrethroid exposure associated with prediabetes?
DEFF Research Database (Denmark)
Hansen, Martin Rune; Jørs, Erik; Lander, Flemming;
2014-01-01
, cumulative exposure) was assessed from questionnaire data. Participants were asked about symptoms of diabetes. Blood samples were analyzed for glycosylated hemoglobin (HbA1c), a measure of glucose regulation. No association was found between pyrethroid exposure and diabetes symptoms. The prevalence...
Cumulative Disadvantage among the Highly Ambitious.
McClelland, Katherine
1990-01-01
Using a social reproduction theory framework, analyzes the process by which high school seniors aspiring to high-level positions are sorted out after graduation. Analyzes early educational attainments and changes in occupational expectations. Shows a process of cumulative disadvantage in which White males are more likely to achieve their goals.…
Pavlovian conditioning and cumulative reinforcement rate.
Harris, Justin A; Patterson, Angela E; Gharaei, Saba
2015-04-01
In 5 experiments using delay conditioning of magazine approach with rats, reinforcement rate was varied either by manipulating the mean interval between onset of the conditioned stimulus (CS) and unconditioned stimulus (US) or by manipulating the proportion of CS presentations that ended with the US (trial-based reinforcement rate). Both manipulations influenced the acquisition of responding. In each experiment, a specific comparison was made between 2 CSs that differed in their mean CS-US interval and in their trial-based reinforcement rate, such that the cumulative reinforcement rate-the cumulative duration of the CS between reinforcements-was the same for the 2 CSs. For example, a CS reinforced on 100% of trials with a mean CS-US interval of 60 s was compared with a CS reinforced on 33% of trials and a mean duration of 20 s. Across the 5 experiments, conditioning was virtually identical for the 2 CSs with matched cumulative reinforcement rate. This was true as long as the timing of the US was unpredictable and, thus, response rates were uniform across the length of the CS. We conclude that the effects of CS-US interval and of trial-based reinforcement rate are reducible entirely to their common effect on cumulative reinforcement rate. We discuss the implications of this for rate-based, trial-based, and real-time associative models of conditioning.
An Axiomatization of Cumulative Prospect Theory
Wakker, P.P.; Tversky, A.
1993-01-01
This paper presents a method for axiomatizing a variety of models for decision making under uncertainty, including Expected Utility and Cumulative Prospect Theory. This method identifies, for each model, the situations that permit consistent inferences about the ordering of value differences. Exampl
Cumulative Disadvantage among the Highly Ambitious.
McClelland, Katherine
1990-01-01
Using a social reproduction theory framework, analyzes the process by which high school seniors aspiring to high-level positions are sorted out after graduation. Analyzes early educational attainments and changes in occupational expectations. Shows a process of cumulative disadvantage in which White males are more likely to achieve their goals.…
Neutron source capability assessment for cumulative fission yields measurements
Energy Technology Data Exchange (ETDEWEB)
Descalle, M A; Dekin, W; Kenneally, J
2011-04-06
A recent analysis of high-quality cumulative fission yields data for Pu-239 published in the peer-reviewed literature showed that the quoted experimental uncertainties do not allow a clear statement on how the fission yields vary as a function of energy. [Prussin2009] To make such a statement requires a set of experiments with well 'controlled' and understood sources of experimental errors to reduce uncertainties as low as possible, ideally in the 1 to 2% range. The Inter Laboratory Working Group (ILWOG) determined that Directed Stockpile Work (DSW) would benefit from an experimental program with the stated goal to reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Following recent discussions between Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL), there is a renewed interest in developing a concerted experimental program to measure fission yields in a neutron energy range from thermal energy (0.025 eV) to 14 MeV with an emphasis on discrete energies from 0.5 to 4 MeV. Ideally, fission yields would be measured at single energies, however, in practice there are only 'quasi-monoenergetic' neutrons sources of finite width. This report outlines a capability assessment as of June 2011 of available neutron sources that could be used as part of a concerted experimental program to measure cumulative fission yields. In a framework of international collaborations, capabilities available in the United States, at the Atomic Weapons Establishment (AWE) in the United Kingdom and at the Commissariat Energie Atomique (CEA) in France are listed. There is a need to develop an experimental program that will reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Fission and monoenergetic neutron sources
Self-Consistent Description of Multipole Strength in Exotic Nuclei I: Method
Terasaki, J; Bender, M; Dobaczewski, J; Nazarewicz, W; Stoitsov, M V
2004-01-01
We use the canonical Hartree-Fock-Bogoliubov basis to implement a completely self-consistent quasiparticle-random-phase approximation with arbitrary Skyrme energy density functionals and density-dependent pairing functionals. The point of the approach is to accurately describe multipole strength functions in spherical even-even nuclei, including weakly-bound drip-line systems. We describe the method and carefully test its accuracy, particularly in handling spurious modes. To illustrate our approach, we calculate isoscalar and isovector monopole, dipole, and quadrupole strength functions in several Sn isotopes, both in the stable region and at the drip lines.
Enhancing monochromatic multipole emission by a subwavelength enclosure of degenerate Mie resonances
Zhao, Jiajun
2017-07-06
Sound emission is inefficient at low frequencies as limited by source size. This letter presents enhancing emission of monochromatic monopole and multipole sources by enclosing the source with a subwavelength circular enclosure filled of an anisotropic material of a low radial sound speed. The anisotropy is associated with an infinite tangential density along the azimuth. Numerical simulations show that emission gain is produced at frequencies surrounding degenerate Mie resonant frequencies of the enclosure, and meanwhile the radiation directivity pattern is well preserved. The degeneracy is theoretically analyzed. A realization of the material is suggested by using a space-coiling structure.
Chremmos, Ioannis; Giamalaki, Melpomeni; Yannopapas, Vassilios; Paspalakis, Emmanuel
2014-01-01
We present a formulation for deriving effective medium properties of infinitely periodic two-dimensional metamaterial lattice structures beyond the static and quasi-static limits. We utilize the multipole expansions, where the polarization currents associated with the supported Bloch modes are expressed via the electric dipole, magnetic dipole, and electric quadrupole moments per unit length. We then propose a method to calculate the Bloch modes based on the lattice geometry and individual unit element structure. The results revert to well-known formulas in the quasistatic limit and are useful for the homogenization of nanorod-type metamaterials which are frequently used in optical applications.
Plasma confinement time in trimix-M galatea multipole magnetic trap
Bishaev, A. M.; Bugrova, A. I.; Kozintseva, M. V.; Lipatov, A. S.; Sigov, A. S.; Kharchevnikov, V. K.
2010-05-01
The confinement time of hydrogen plasma trapped in a Trimix-M magnetic multipole galatea was studied in a range of plasma densities (1 × 1016 - 6 × 1018 m-3) and ion energies (˜100-300 eV). It is established that (i) the confinement time increases with decreasing plasma density in the trap and (ii) as the barrier magnetic field is increased, the plasma confinement time grows faster than according to a linear law. The obtained results are indicative of a collisional character of plasma diffusion through the barrier field in the trap.
Adaptive grouping for the higher-order multilevel fast multipole method
DEFF Research Database (Denmark)
Borries, Oscar Peter; Jørgensen, Erik; Meincke, Peter
2014-01-01
An alternative parameter-free adaptive approach for the grouping of the basis function patterns in the multilevel fast multipole method is presented, yielding significant memory savings compared to the traditional Octree grouping for most discretizations, particularly when using higher-order basis...... functions. Results from both a uniformly and nonuniformly meshed scatterer are presented, showing how the technique is worthwhile even for regular meshes, and demonstrating that there is no loss of accuracy in spite of the large reduction in memory requirements and the relatively low computational cost....
Application of A Fast Multipole BIEM for Flow Diffraction from A 3D Body
Institute of Scientific and Technical Information of China (English)
滕斌; 宁德志
2004-01-01
A Fast Multipole Method (FMM) is developed as a numerical approach to the reduction of the computational cost and requirement memory capacity for a large in solving large-scale problems. In this paper it is applied to the boundary integral equation method (BIEM) for current diffraction from arbitrary 3D bodies. The boundary integral equation is discretized by higher order elements, the FMM is applied to avoid the matrix/vector product, and the resulting algebraic equation is solved by the Generalized Conjugate Residual method (GCR). Numerical examination shows that the FMM is more efficient than the direct evaluation method in computational cost and storage of computers.
Kinjo, Ryota; Kagamihata, Akihiro; Seike, Takamitsu; Kishimoto, Hikaru; Ohashi, Haruhiko; Yamamoto, Shigeru; Tanaka, Takashi
2017-07-01
A lightweight-compact variable-gap undulator (LCVGU) having the force-cancellation system based on the multipole monolithic magnets (MMMs) has been developed. The LCVGU is free from the heavy mechanical frames, which is a fundamental element specific to conventional variable-gap undulators (VGUs) because of a strong attractive force, and thus the cost and time for construction and installation are expected to be significantly reduced; the MMMs counteract the strong attractive force in a cost-effective manner. Results of mechanical tests and magnetic-field measurements of two prototype LCVGUs equipped with the proposed force cancellation system have revealed the comparable performance with the conventional VGUs.
Institute of Scientific and Technical Information of China (English)
BAI Sha; P. Bambade; WANG Dou; GAO Jie; M. Woodley; M. Masuzawa
2012-01-01
The ATF2 project is the final focus system prototype for the ILC and CLIC linear collider projects,with the purpose of reaching a 37nm vertical beam size at the interaction point.In the nanometer beam size regime,higher order multipoles in magnets become a crucial point for consideration.The strength and rotation angle of the ATF2 QEA magnets were reconstructed from the IHEP measurements and compared with the KEK ones to be identical.Based on the study of the skew multipoles sensitivity,we report on the analysis of the possible mitigation of the measured multipoles.A suggestion is given which will benefit the ATF2 present commissioning to reach the goal beam size,and also the reduced β optics in future.
Complexity and demographic explanations of cumulative culture.
Directory of Open Access Journals (Sweden)
Adrien Querbes
Full Text Available Formal models have linked prehistoric and historical instances of technological change (e.g., the Upper Paleolithic transition, cultural loss in Holocene Tasmania, scientific progress since the late nineteenth century to demographic change. According to these models, cumulation of technological complexity is inhibited by decreasing--while favoured by increasing--population levels. Here we show that these findings are contingent on how complexity is defined: demography plays a much more limited role in sustaining cumulative culture in case formal models deploy Herbert Simon's definition of complexity rather than the particular definitions of complexity hitherto assumed. Given that currently available empirical evidence doesn't afford discriminating proper from improper definitions of complexity, our robustness analyses put into question the force of recent demographic explanations of particular episodes of cultural change.
Avoiding Program-Induced Cumulative Overload (PICO).
Orr, Robin; Knapik, Joseph J; Pope, Rodney
2016-01-01
This article defines the concept of program-induced cumulative overload (PICO), provides examples, and advises ways to mitigate the adverse effects. PICO is the excessive cumulative physical workload that can be imparted to military personnel by a military training program with an embedded physical training component. PICO can be acute (accumulating within a single day) or chronic (accumulating across the entirety of the program) and results in adverse outcomes for affected personnel, including detrimental fatigue, performance degradation, injuries, or illness. Strategies to mitigate PICO include focusing administration and logistic practices during the development and ongoing management of a trainee program and implementing known musculoskeletal injury prevention strategies. More training is not always better, and trainers need to consider the total amount of physical activity that military personnel experience across both operational training and physical training if PICO is to be mitigated.
Sharing a quota on cumulative carbon emissions
Raupach, Michael R.; Davis, Steven J.; Peters, Glen P.; Andrew, Robbie M.; Canadell, Josep G.; Ciais, Philippe; Friedlingstein, Pierre; Jotzo, Frank; van Vuuren, Detlef P.; Le Quéré, Corinne
2014-10-01
Any limit on future global warming is associated with a quota on cumulative global CO2 emissions. We translate this global carbon quota to regional and national scales, on a spectrum of sharing principles that extends from continuation of the present distribution of emissions to an equal per-capita distribution of cumulative emissions. A blend of these endpoints emerges as the most viable option. For a carbon quota consistent with a 2 °C warming limit (relative to pre-industrial levels), the necessary long-term mitigation rates are very challenging (typically over 5% per year), both because of strong limits on future emissions from the global carbon quota and also the likely short-term persistence in emissions growth in many regions.
Structural Vibration Monitoring Using Cumulative Spectral Analysis
Directory of Open Access Journals (Sweden)
Satoru Goto
2013-01-01
Full Text Available This paper describes a resonance decay estimation for structural health monitoring in the presence of nonstationary vibrations. In structural health monitoring, the structure's frequency response and resonant decay characteristics are very important for understanding how the structure changes. Cumulative spectral analysis (CSA estimates the frequency decay by using the impulse response. However, measuring the impulse response of buildings is impractical due to the need to shake the building itself. In a previous study, we reported on system damping monitoring using cumulative harmonic analysis (CHA, which is based on CSA. The current study describes scale model experiments on estimating the hidden resonance decay under non-stationary noise conditions by using CSA for structural condition monitoring.
Cumulative carbon emissions and the Green Paradox
Ploeg, Frederick Van der
2013-01-01
The green paradox states that a gradually more ambitious climate policy such as a renewables subsidy or an anticipated carbon tax induces fossil fuel owners to extract more rapidly and accelerate global warming. However, if extraction becomes more costly as reserves are depleted, such policies also shorten the fossil fuel era, induce more fossil fuel to be left in the earth, and thus curb cumulative carbon emissions. These consequences are relevant, as global warming depends primarily on cumu...
A genetic algorithm for optimizing multi-pole Debye models of tissue dielectric properties
Clegg, J.; Robinson, M. P.
2012-10-01
Models of tissue dielectric properties (permittivity and conductivity) enable the interactions of tissues and electromagnetic fields to be simulated, which has many useful applications in microwave imaging, radio propagation, and non-ionizing radiation dosimetry. Parametric formulae are available, based on a multi-pole model of tissue dispersions, but although they give the dielectric properties over a wide frequency range, they do not convert easily to the time domain. An alternative is the multi-pole Debye model which works well in both time and frequency domains. Genetic algorithms are an evolutionary approach to optimization, and we found that this technique was effective at finding the best values of the multi-Debye parameters. Our genetic algorithm optimized these parameters to fit to either a Cole-Cole model or to measured data, and worked well over wide or narrow frequency ranges. Over 10 Hz-10 GHz the best fits for muscle, fat or bone were each found for ten dispersions or poles in the multi-Debye model. The genetic algorithm is a fast and effective method of developing tissue models that compares favourably with alternatives such as the rational polynomial fit.
Multipole Theory in Electromagnetism: Classical, Quantum and Symmetry Aspects, with Applications
Energy Technology Data Exchange (ETDEWEB)
Sihvola, Ari [Helsinki University of Technology (Finland)
2005-03-11
'Good reasons must, of force, give place to better', observes Brutus to Cassius, according to William Shakespeare in Julius Caesar. Roger Raab and Owen de Lange seem to agree, as they cite this sentence in the concluding chapter of their new book on the importance of exact multipole analysis in macroscopic electromagnetics. Very true and essential to remember in our daily research work. The two scientists from the University of Natal in Pietermaritzburg, South Africa (presently University of KwaZulu-Natal) have been working for a very long time on the accurate description of electric and magnetic response of matter and have published much of their findings in various physics journals. The present book gives us a clear and coherent exposition of many of these results. The important message of Raab and de Lange is that in the macroscopic description of matter, a correct balance between the various orders of electric and magnetic multipole terms has to be respected. If the inclusion of magnetic dipole terms is not complemented with electric quadrupoles, there is a risk of losing the translational invariance of certain important quantities. This means that the values of these quantities depend on the choice of the origin{exclamation_point} 'It can't be Nature, for it is not sense' is another of the apt literary citations in the book. Often monographs written by researchers look like they have been produced using a cut-and-paste technique; earlier published articles are included in the same book but, unfortunately, too little additional effort is expended into moulding the totality into a unified story. This is not the case with Raab and de Lange. The structure and the text flow of the book serve perfectly its important message. After the obligatory introduction of material response to electromagnetic fields, constitutive relations, basic quantum theory and spacetime properties, a chapter follows with transmission and scattering effects where
Multipole and field uniformity tailoring of a 750 MHz rf dipole
Energy Technology Data Exchange (ETDEWEB)
Delayen, Jean R. [JLAB, Old Dominion University; Castillo, Alejandro [JLAB, Old Dominion University
2014-12-01
In recent years great interest has been shown in developing rf structures for beam separation, correction of geometrical degradation on luminosity, and diagnostic applications in both lepton and hadron machines. The rf dipole being a very promising one among all of them. The rf dipole has been tested and proven to have attractive properties that include high shunt impedance, low and balance surface fields, absence of lower order modes and far-spaced higher order modes that simplify their damping scheme. As well as to be a compact and versatile design in a considerable range of frequencies, its fairly simple geometry dependency is suitable both for fabrication and surface treatment. The rf dipole geometry can also be optimized for lowering multipacting risk and multipole tailoring to meet machine specific field uniformity tolerances. In the present work a survey of field uniformities, and multipole contents for a set of 750 MHz rf dipole designs is presented as both a qualitative and quantitative analysis of the inherent flexibility of the structure and its limitations.
A genetic algorithm for optimizing multi-pole Debye models of tissue dielectric properties.
Clegg, J; Robinson, M P
2012-10-01
Models of tissue dielectric properties (permittivity and conductivity) enable the interactions of tissues and electromagnetic fields to be simulated, which has many useful applications in microwave imaging, radio propagation, and non-ionizing radiation dosimetry. Parametric formulae are available, based on a multi-pole model of tissue dispersions, but although they give the dielectric properties over a wide frequency range, they do not convert easily to the time domain. An alternative is the multi-pole Debye model which works well in both time and frequency domains. Genetic algorithms are an evolutionary approach to optimization, and we found that this technique was effective at finding the best values of the multi-Debye parameters. Our genetic algorithm optimized these parameters to fit to either a Cole-Cole model or to measured data, and worked well over wide or narrow frequency ranges. Over 10 Hz-10 GHz the best fits for muscle, fat or bone were each found for ten dispersions or poles in the multi-Debye model. The genetic algorithm is a fast and effective method of developing tissue models that compares favourably with alternatives such as the rational polynomial fit.
Sihvola, Ari
2005-03-01
`Good reasons must, of force, give place to better', observes Brutus to Cassius, according to William Shakespeare in Julius Caesar. Roger Raab and Owen de Lange seem to agree, as they cite this sentence in the concluding chapter of their new book on the importance of exact multipole analysis in macroscopic electromagnetics. Very true and essential to remember in our daily research work. The two scientists from the University of Natal in Pietermaritzburg, South Africa (presently University of KwaZulu-Natal) have been working for a very long time on the accurate description of electric and magnetic response of matter and have published much of their findings in various physics journals. The present book gives us a clear and coherent exposition of many of these results. The important message of Raab and de Lange is that in the macroscopic description of matter, a correct balance between the various orders of electric and magnetic multipole terms has to be respected. If the inclusion of magnetic dipole terms is not complemented with electric quadrupoles, there is a risk of losing the translational invariance of certain important quantities. This means that the values of these quantities depend on the choice of the origin! `It canÂ't be Nature, for it is not sense' is another of the apt literary citations in the book. Often monographs written by researchers look like they have been produced using a cut-and-paste technique; earlier published articles are included in the same book but, unfortunately, too little additional effort is expended into moulding the totality into a unified story. This is not the case with Raab and de Lange. The structure and the text flow of the book serve perfectly its important message. After the obligatory introduction of material response to electromagnetic fields, constitutive relations, basic quantum theory and spacetime properties, a chapter follows with transmission and scattering effects where everything seems to work well with the `old
Orientation measurement based on magnetic inductance by the extended distributed multi-pole model.
Wu, Fang; Moon, Seung Ki; Son, Hungsun
2014-06-27
This paper presents a novel method to calculate magnetic inductance with a fast-computing magnetic field model referred to as the extended distributed multi-pole (eDMP) model. The concept of mutual inductance has been widely applied for position/orientation tracking systems and applications, yet it is still challenging due to the high demands in robust modeling and efficient computation in real-time applications. Recently, numerical methods have been utilized in design and analysis of magnetic fields, but this often requires heavy computation and its accuracy relies on geometric modeling and meshing that limit its usage. On the other hand, an analytical method provides simple and fast-computing solutions but is also flawed due to its difficulties in handling realistic and complex geometries such as complicated designs and boundary conditions, etc. In this paper, the extended distributed multi-pole model (eDMP) is developed to characterize a time-varying magnetic field based on an existing DMP model analyzing static magnetic fields. The method has been further exploited to compute the mutual inductance between coils at arbitrary locations and orientations. Simulation and experimental results of various configurations of the coils are presented. Comparison with the previously published data shows not only good performance in accuracy, but also effectiveness in computation.
Fast multipole boundary element analysis of 2D viscoelastic composites with imperfect interfaces
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
A fast multipole boundary element method(FMBEM)is developed for the analysis of 2D linear viscoelastic composites with imperfect viscoelastic interfaces.The transformed fast multipole formulations are established using the time domain method. To simulate the viscoelastic behavior of imperfect interfaces that are frequently encountered in practice,the Kelvin type model is introduced.The FMBEM is further improved by incorporating naturally the interaction among inclusions as well as eliminating the phenomenon of material penetration.Since all the integrals are evaluated analytically,high accuracy and fast convergence of the numerical scheme are obtained.Several numerical examples,including planar viscoelastic composites with a single inclusion or randomly distributed multi-inclusions are presented.The numerical results are compared with the developed analytical solutions,which illustrates that the proposed FMBEM is very efficient in determining the macroscopic viscoelastic behavior of the particle-reinforced composites with the presence of imperfect interfaces.The laboratory measurements of the mixture creep compliance of asphalt concrete are also compared with the prediction by the developed model.
Lu, Benzhuo; Cheng, Xiaolin; Huang, Jingfang; McCammon, J. Andrew
2013-11-01
A Fortran program package is introduced for rapid evaluation of the electrostatic potentials and forces in biomolecular systems modeled by the linearized Poisson-Boltzmann equation. The numerical solver utilizes a well-conditioned boundary integral equation (BIE) formulation, a node-patch discretization scheme, a Krylov subspace iterative solver package with reverse communication protocols, and an adaptive new version of the fast multipole method in which the exponential expansions are used to diagonalize the multipole-to-local translations. The program and its full description, as well as several closely related libraries and utility tools are available at http://lsec.cc.ac.cn/~lubz/afmpb.html and a mirror site at http://mccammon.ucsd.edu/. This paper is a brief summary of the program: the algorithms, the implementation and the usage. Restrictions: Only three or six significant digits options are provided in this version. Unusual features: Most of the codes are in Fortran77 style. Memory allocation functions from Fortran90 and above are used in a few subroutines. Additional comments: The current version of the codes is designed and written for single core/processor desktop machines. Check http://lsec.cc.ac.cn/lubz/afmpb.html for updates and changes. Running time: The running time varies with the number of discretized elements (N) in the system and their distributions. In most cases, it scales linearly as a function of N.
A Fast Multipole Algorithm with Virtual Cube Partitioning for 3-D Capacitance Extraction
Institute of Scientific and Technical Information of China (English)
YANGZhaozhi; WANGZeyi
2004-01-01
In this paper a fast indirect boundaryelement method based on the multipole algorithm for capacitance extraction of three-dimensional (3-D) geometries, virtual cube multipole algorithm, is described. First,each 2-D boundary element is regarded as a set of particles with charge rather than a single particle, so the relations between the positions of elements themselves are considered instead of the relations between the center-points of the elements, and a new strategy for cube partitioning is introduced. This strategy overcomes the inadequacy of the methods that associating panels to particles, does not need to break up every panel contained in more than one cube, and has higher speed and precision. Next, a new method is proposed to accelerate the potential integration between the panels that are near to each other. Making good use of the similarity in the 2-D boundary integration,the fast potential integral approach decreases the burden of direct potential computing. Experiments confirm that the algorithm is accurate and has nearly linear computational growth as O(nm), where n is the number of panels and rn is the number of conductors. The new algorithm is implemented and the performance is compared with previous algorithms, such as Fastcap2 of MIT, for k×k bus examples.
Local geometry of electromagnetic fields and its role in molecular multipole transitions.
Yang, Nan; Cohen, Adam E
2011-05-12
Electromagnetic fields with complex spatial variation routinely arise in Nature. We study the response of a small molecule to monochromatic fields of arbitrary three-dimensional geometry. First, we consider the allowed configurations of the fields and field gradients at a single point in space. Many configurations cannot be generated from a single plane wave, regardless of polarization, but any allowed configuration can be generated by superposition of multiple plane waves. There is no local configuration of the fields and gradients that requires near-field effects. Second, we derive a set of local electromagnetic quantities, each of which couples to a particular multipole transition. These quantities are small or zero in plane waves, but can be large in regions of certain superpositions of plane waves. Our findings provide a systematic framework for designing far-field and near-field experiments to drive multipole transitions. The proposed experiments provide information on molecular structure that is inaccessible to other spectroscopic techniques and open the possibility for new types of optical control of molecules.
Expansive Soil Crack Depth under Cumulative Damage
Directory of Open Access Journals (Sweden)
Bei-xiao Shi
2014-01-01
Full Text Available The crack developing depth is a key problem to slope stability of the expansive soil and its project governance and the crack appears under the roles of dry-wet cycle and gradually develops. It is believed from the analysis that, because of its own cohesion, the expansive soil will have a certain amount of deformation under pulling stress but without cracks. The soil body will crack only when the deformation exceeds the ultimate tensile strain that causes cracks. And it is also believed that, due to the combined effect of various environmental factors, particularly changes of the internal water content, the inherent basic physical properties of expansive soil are weakened, and irreversible cumulative damages are eventually formed, resulting in the development of expansive soil cracks in depth. Starting from the perspective of volumetric strain that is caused by water loss, considering the influences of water loss rate and dry-wet cycle on crack developing depth, the crack developing depth calculation model which considers the water loss rate and the cumulative damages is established. Both the proposal of water loss rate and the application of cumulative damage theory to the expansive soil crack development problems try to avoid difficulties in matrix suction measurement, which will surely play a good role in promoting and improving the research of unsaturated expansive soil.
EPA Workshop on Epigenetics and Cumulative Risk ...
Agenda Download the Workshop Agenda (PDF) The workshop included presentations and discussions by scientific experts pertaining to three topics (i.e., epigenetic changes associated with diverse stressors, key science considerations in understanding epigenetic changes, and practical application of epigenetic tools to address cumulative risks from environmental stressors), to address several questions under each topic, and included an opportunity for attendees to participate in break-out groups, provide comments and ask questions. Workshop Goals The workshop seeks to examine the opportunity for use of aggregate epigenetic change as an indicator in cumulative risk assessment for populations exposed to multiple stressors that affect epigenetic status. Epigenetic changes are specific molecular changes around DNA that alter expression of genes. Epigenetic changes include DNA methylation, formation of histone adducts, and changes in micro RNAs. Research today indicates that epigenetic changes are involved in many chronic diseases (cancer, cardiovascular disease, obesity, diabetes, mental health disorders, and asthma). Research has also linked a wide range of stressors including pollution and social factors with occurrence of epigenetic alterations. Epigenetic changes have the potential to reflect impacts of risk factors across multiple stages of life. Only recently receiving attention is the nexus between the factors of cumulative exposure to environmental
Observation of Rydberg-atom macrodimers: micrometer-sized diatomic molecules
Saßmannshausen, Heiner
2016-01-01
Long-range metastable molecules consisting of two cesium atoms in high Rydberg states have been observed in an ultracold gas. A sequential three-photon two-color photoassociation scheme was employed to form these molecules in states which correlate to $np(n+1)s$ dissociation asymptotes. Spectral signatures of bound molecular states are clearly resolved at the positions of avoided crossings between long-range van der Waals potential curves. The experimental results are in agreement with simulations based on a detailed model of the long-range multipole-multipole interactions of Rydberg-atom pair states. We show that a full model is required to accurately predict the occurrence of bound Rydberg macrodimers. The macrodimers are distinguished from repulsive molecular states by their behavior with respect to spontaneous ionization and possible decay channels are discussed.
Jansen, Thomas L. C.
2014-01-01
The effect of solvent polarizability and multipole effects on the amide I vibrational spectra of a peptide unit is investigated. Four molecular dynamics force fields of increasing complexity for the solvent are used to model both the linear absorption and two-dimensional infrared spectra. It is obse
Cumulative risks of foster care placement for Danish children
National Research Council Canada - National Science Library
Fallesen, Peter; Emanuel, Natalia; Wildeman, Christopher
2014-01-01
Although recent research suggests that the cumulative risk of foster care placement is far higher for American children than originally suspected, little is known about the cumulative risk of foster...
Recursive Numerical Evaluation of the Cumulative Bivariate Normal Distribution
Meyer, Christian
2010-01-01
We propose an algorithm for evaluation of the cumulative bivariate normal distribution, building upon Marsaglia's ideas for evaluation of the cumulative univariate normal distribution. The algorithm is mathematically transparent, delivers competitive performance and can easily be extended to arbitrary precision.
Climate mitigation: sustainable preferences and cumulative carbon
Buckle, Simon
2010-05-01
We develop a stylized AK growth model with both climate damages to ecosystem goods and services and sustainable preferences that allow trade-offs between present discounted utility and long-run climate damages. The simplicity of the model permits analytical solutions. Concern for the long-term provides a strong driver for mitigation action. One plausible specification of sustainable preferences leads to the result that, for a range of initial parameter values, an optimizing agent would choose a level of cumulative carbon dioxide (CO2) emissions independent of initial production capital endowment and CO2 levels. There is no technological change so, for economies with sufficiently high initial capital and CO2 endowments, optimal mitigation will lead to disinvestment. For lower values of initial capital and/or CO2 levels, positive investment can be optimal, but still within the same overall level of cumulative emissions. One striking aspect of the model is the complexity of possible outcomes, in addition to these optimal solutions. We also identify a resource constrained region and several regions where climate damages exceed resources available for consumption. Other specifications of sustainable preferences are discussed, as is the case of a hard constraint on long-run damages. Scientists are currently highlighting the potential importance of the cumulative carbon emissions concept as a robust yet flexible target for climate policymakers. This paper shows that it also has an ethical interpretation: it embodies an implicit trade off in global welfare between present discounted welfare and long-term climate damages. We hope that further development of the ideas presented here might contribute to the research and policy debate on the critical areas of intra- and intergenerational welfare.
Long and Short Term Cumulative Structural Priming Effects
Kaschak, Michael P.; Kutta, Timothy J.; Coyle, Jacqueline M.
2012-01-01
We present six experiments that examine cumulative structural priming effects (i.e., structural priming effects that accumulate across many utterances). Of particular interest is whether (1) cumulative priming effects transfer across language production tasks and (2) the transfer of cumulative priming effects across tasks persists over the course of a week. Our data suggest that cumulative structural priming effects do transfer across language production tasks (e.g., from written stem complet...
Preserved cumulative semantic interference despite amnesia
Directory of Open Access Journals (Sweden)
Gary Michael Oppenheim
2015-05-01
As predicted by Oppenheim et al’s (2010 implicit incremental learning account, WRP’s BCN RTs demonstrated strong (and significant repetition priming and semantic blocking effects (Figure 1. Similar to typical results from neurally intact undergraduates, WRP took longer to name pictures presented in semantically homogeneous blocks than in heterogeneous blocks, an effect that increased with each cycle. This result challenges accounts that ascribe cumulative semantic interference in this task to explicit memory mechanisms, instead suggesting that the effect has the sort of implicit learning bases that are typically spared in hippocampal amnesia.
Cumulant matching for independent source extraction.
Phlypo, Ronald; Zarzoso, Vicente; Comon, Pierre; Lemahieu, Ignace
2008-01-01
In this work we show how one can make use of priors on signal statistics under the form of cumulant guesses to extract an independent source from an observed mixture. The advantage of using statistical priors on the signal lies in the fact that no specific knowledge is needed about its temporal behavior, neither about its spatial distribution. We show that these statistics can be obtained either by reasoning on the theoretical values of a supposed waveform, either by using a subset of the observations from which we know that their statistics are merely hindered by interferences. Results on an electro-cardiographic recording confirm the above assumptions.
Energy Technology Data Exchange (ETDEWEB)
Strauss, Lewis L.
1956-07-30
The sixteenth through the twentieth semiannual reports of the United States Atomic Energy Commission to Congress are covered in this cumulative index, which included both a name and subject index as aids to finding information in the full reports.. The full semiannual reports themselves cover the major unclassified activities of the Commission from January 1954 through June 1956.
Energy Technology Data Exchange (ETDEWEB)
Dean, Gordon
1954-01-31
The first fifteen semiannual reports of the United States Atomic Energy Commission to Congress cover the major unclassified activities of the Commission from January 1947 through December 1953. This cumulative name and subject index provides a guide to the information published in these reports.
Ab initio atom-atom potentials using CamCASP: Application to pyridine
Misquitta, Alston J
2015-01-01
In Part I of this two-part investigation we described a methodology for the development of robust, analytic, many-body atom-atom potentials for small organic molecules from first principles. Here we demonstrate how these theoretical ideas, which are implemented in the CamCASP suite of programs, can be used to develop a series of many-body potentials for the pyridine system. Even the simplest of these potentials exhibit r.m.s. errors of only about 0.5kJ mol$^{-1}$, significantly surpassing the best empirical potentials. Further, the functional form can be made systematically more elaborate so as to improve the accuracy without a significant increase in the human-time spent in their generation. We investigate the effects of anisotropy, rank of multipoles, and choice of polarizability and dispersion models.
A Missing Link in the Evolution of the Cumulative Recorder
Asano, Toshio; Lattal, Kennon A.
2012-01-01
A recently recovered cumulative recorder provides a missing link in the evolution of the cumulative recorder from a modified kymograph to a reliably operating, scientifically and commercially successful instrument. The recorder, the only physical evidence of such an early precommercial cumulative recorder yet found, was sent to Keio University in…
Original and cumulative prospect theory: a discussion of empirical differences
P.P. Wakker; H. Fennema
1997-01-01
This note discusses differences between prospect theory and cumulative prospect theory. It shows that cumulative prospect theory is not merely a formal correction of some theoretical problems in prospect theory, but it also gives different predictions. Experiments are described that favor cumulative
Analysis and Design of Backing Beam for Multipole Wiggler (MPW14) at PLS
Lee, Hong-Gi; Jung, Young-Gyu; Park, Ki-Hyeon; Sik Han, Hong; Suck Suh, Hyung; Wha Chung, Chin; Woo Lee, Wol
2005-01-01
Pohang Accelerator Laboratory (PAL) had developed and installed a Multipole Wiggler (MPW14) to utilize high energy synchrotron radiation at Pohang Light Source (PLS). The MPW14 is a hybrid type device with period of 14 cm, minimum gap of 14 mm, maximum flux density of 2.02 Tesla and total magnetic structure length of 2056 mm. The support locations and structure of an insertion device are optimized to achieve a minimum deflection due to the magnetic loads. A Finite Element Analysis (FEA) is performed to find out the amount of maximum deflection and optimal support positions on the backing beam, the support and drive structures of the MPW14 under expected magnetic load of 14 tons. To reduce the deflection effect further, two springs are designed and installed to compensate the gap dependent magnetic loads. The optimized deflection is estimated to be about 20.6 ? while the deflection before optimization is 238 ?.
Role of multipole moments in electric-field-induced order of dense molecular systems.
Acebal, Pablo; Carretero, Luis; Blaya, Salvador
2010-07-12
A new model is developed to describe the orientational order of dense molecular systems under an applied external electric field as a function of the n-particle distribution functions of a system under no external perturbation. From an approximation of this expression, the effects of several variables on this orientational order, such as the microscopic properties of the oriented molecules (the molecular geometry and multipole moments) and the solvent or matrix properties, are studied. The theoretical predictions show that, for a correct description of the orientational order, quadrupole and octupole moments must be included, as they play an important role in the orientational order achieved, depending on the molecular geometry. Furthermore, to verify the validity of the model, theoretical predictions are compared with experimental results, and show a good concordance.
Periodic boundary conditions and the error-controlled fast multipole method
Energy Technology Data Exchange (ETDEWEB)
Kabadshow, Ivo
2012-08-22
The simulation of pairwise interactions in huge particle ensembles is a vital issue in scientific research. Especially the calculation of long-range interactions poses limitations to the system size, since these interactions scale quadratically with the number of particles. Fast summation techniques like the Fast Multipole Method (FMM) can help to reduce the complexity to O(N). This work extends the possible range of applications of the FMM to periodic systems in one, two and three dimensions with one unique approach. Together with a tight error control, this contribution enables the simulation of periodic particle systems for different applications without the need to know and tune the FMM specific parameters. The implemented error control scheme automatically optimizes the parameters to obtain an approximation for the minimal runtime for a given energy error bound.
The Fast Multipole Method and Point Dipole Moment Polarizable Force Fields
Coles, Jonathan P
2014-01-01
We present a momentum conserving implementation of the fast multipole method for computing coulombic electrostatic and polarization forces from polarizable force-fields based on induced point dipole moments. We demonstrate the expected $O(N)$ scaling of that approach by performing single energy point calculations on hexamer protein subunits of the mature HIV-1 capsid. We also show the long time energy conservation in molecular dynamics at the nanosecond scale by performing simulations of a protein complex embedded in a coarse-grained solvent using both a standard integrator and a multiple time step one. Our tests show the applicability of FMM combined with state-of-the-art chemical models in molecular dynamical systems.
Efficient analysis of dielectric radomes using multilevel fast multipole algorithm with CRWG basis
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
A full-wave analysis of the electromagnetic problem of a three-dimensional (3-D) antenna radiating through a 3-D dielectric radome is preserued.The problem is formulated using the Poggio-Miller-Chang-Harrington-Wu(PMCHW) approach for homogeneous dielectric objects and the electric field integral equation for conducting objects.The integral equations are discretized by the method of moment (MoM),in which the conducting and dielectric surface/interfaces are represented by curvilinear triangular patches and the unknown equivalent electric and magnetic currents are expanded using curvilinear RWG basis functions.The resultant matrix equation is then solved by the multilevel fast multipole algorithm (MLFMA) and fast far-field approximation (FAFFA) is used to further accelerate the computation.The radiation patterns of dipole arrays in the presence of radomes are presented.The numerical results demonstrate the accuracy and versatility of this method.
Higher-order multipole amplitude measurement in $\\pspto\\g\\chict$
,
2011-01-01
Using $106\\times10^6$ $\\psp$ events collected with the BESIII detector at the BEPCII storage ring, the higher-order multipole amplitudes in the radiative transition $\\pspto\\g\\chictto\\g\\pp/\\g\\kk$ are measured. A fit to the $\\chict$ production and decay angular distributions yields $M2=0.046\\pm0.010\\pm0.013$ and $E3=0.015\\pm0.008\\pm0.018$, where the first errors are statistical and the second systematic. Here $M2$ denotes the normalized magnetic quadrupole amplitude and $E3$ the normalized electric octupole amplitude. This measurement shows evidence for the existence of the $M2$ signal with $4.4\\sigma$ statistical significance and is consistent with the charm quark having no anomalous magnetic moment.
Mihalcea, Bogdan M; Stan, Cristina; Visan, Gina T; Ganciu, Mihai; Filinov, Vladimir E; Lapitsky, Dmitry S; Deputatova, Lidiya V; Syrovatka, Roman A
2015-01-01
Trapping of microparticles and aerosols is of great interest for physics and chemistry. We report microparticle trapping in multipole linear Paul trap geometries, operating under Standard Ambient Temperature and Pressure (SATP) conditions. An 8-electrode and a 12-electrode linear trap geometries have been designed and tested with an aim to achieve trapping for larger number of particles and to study microparticle dynamical stability in electrodynamic fields. We report emergence of planar and volume ordered structures of the microparticles, depending on the a.c. trapping frequency and particle specific charge ratio. The electric potential within the trap was mapped using the electrolytic tank method. Particle dynamics was simulated using a stochastic Langevin equation. We emphasize extended regions of stable trapping with respect to quadrupole traps, as well as good agreement between experiment and numerical simulations.
Axion like particle Dark Matter may explain the anomalies of CMB multipoles
Yang, Qiaoli
2015-01-01
The axions/axion like particles (ALPs) may constitute a major part of dark matter. Recently people find that dark matter axions can thermalize and form a Bose-Einstein condensate with a long correlation length. For the ALPs the thermalization scenario is similar. We find that for the linear regime of perturbation the ALPs are different from ordinary point like dark matter particles with additional terms in the first order velocity equation. The differences are especially compelling for string theory originated lighter ALPs. Also, axions/ALPs with a long correlation length can be thermalized due to gravitational interaction therefore alter the entropy of large scale. We propose that it can be a mechanism to explain the anomalies of Cosmic Microwave Background (CMB) multipoles if the mass of ALPs is order of $10^{-29}{\\rm eV}$.
Institute of Scientific and Technical Information of China (English)
Pan Xiaomin; Sheng Xinqing
2008-01-01
A general and efficient parallel approach is proposed for the first time to parallelize the hybrid finite-element-boundary-integral-multi-level fast multipole algorithm (FE-BI-MLFMA). Among many algorithms of FE-BI-MLFMA, the decomposition algorithm (DA) is chosen as a basis for the parallelization of FE-BI-MLFMA because of its distinct numerical characteristics suitable for parallelization. On the basis of the DA, the parallelization of FE-BI-MLFMA is carried out by employing the parallelized multi-frontal method for the matrix from the finite-element method and the parallelized MLFMA for the matrix from the boundary integral method respectively. The programming and numerical experiments of the proposed parallel approach are carried out in the high perfor-mance computing platform CEMS-Liuhui. Numerical experiments demonstrate that FE-BI-MLFMA is efficiently parallelized and its computational capacity is greatly improved without losing accuracy, efficiency, and generality.
A circuit QED controlled-Z ``AMP'' gate (Adiabatic MultiPole gate)
McKay, David C.; Naik, Ravi; Bishop, Lev S.; Schuster, David I.
2014-03-01
Circuit quantum electrodynamics -- superconducting Josephson junction ``transmon'' qubits coupled via microwave cavities -- is a promising route towards scalable quantum computing. Here we report on experiments coupling two transmon qubits through multiple strongly coupled planar superconducting cavities -- the multipole cavity QED architecture. This design enables large interactions (mediated by real cavity photons) when the transmons are resonant with the cavities, and low off rates when the qubits are tuned away from the cavity resonance. In this talk we will discuss our gate protocol -- the AMP gate -- and report on producing a high fidelity Bell state (| gg > + | ee >) measured from state and process tomography. We will discuss future plans for scaling this architecture beyond two qubits.
Neutron diffraction study of multipole order in light rare-earth hexaborides
Indian Academy of Sciences (India)
J-M Mignat; J Robert; M Sera; F Iga
2008-10-01
Multipole interactions are known to play a central role in the unconventional properties of light rare-earth hexaborides and especially of CeB6. Substituting Pr at the Ce sites has the effect of enhancing exchange interactions and changing the symmetry of the local 4f charge distribution, while suppressing the octupole moment. The (,) magnetic phase diagrams of the CePr1-B6 compounds display a large variety of ordered phases involving magnetic and/or charge degrees of freedom. Here we focus on the compound Ce0.7Pr0:3B6, which is located slightly beyond the Pr concentration where the antiferroquadrupolar phase of pure CeB6 is suppressed in zero field. The different magnetic structures have been characterized by neutron diffraction and their origin is discussed in connection with recent non-resonant X-ray results by Tanaka et al.
From geodesics of the multipole solutions to the perturbed Kepler problem
Hernandez-Pastora, J L; 10.1103/PhysRevD.82.104001
2010-01-01
A static and axisymmetric solution of the Einstein vacuum equations with a finite number of Relativistic Multipole Moments (RMM) is written in MSA coordinates up to certain order of approximation, and the structure of its metric components is explicitly shown. From the equation of equatorial geodesics we obtain the Binet equation for the orbits and it allows us to determine the gravitational potential that leads to the equivalent classical orbital equations of the perturbed Kepler problem. The relativistic corrections to Keplerian motion are provided by the different contributions of the RMM of the source starting from the Monopole (Schwarzschild correction). In particular, the perihelion precession of the orbit is calculated in terms of the quadrupole and 2$^4$-pole moments. Since the MSA coordinates generalize the Schwarzschild coordinates, the result obtained allows measurement of the relevance of the quadrupole moment in the first order correction to the perihelion frequency-shift.
Cumulative Environmental Management Association : Wood Buffalo Region
Energy Technology Data Exchange (ETDEWEB)
Friesen, B. [Syncrude Canada Ltd., Edmonton, AB (Canada)
2001-07-01
The recently announced oil sands development of the Wood Buffalo Region in Alberta was the focus of this power point presentation. Both mining and in situ development is expected to total $26 billion and 2.6 million barrels per day of bitumen production. This paper described the economic, social and environmental challenges facing the resource development of this region. In addition to the proposed oil sands projects, this region will accommodate the needs of conventional oil and gas production, forestry, building of pipelines and power lines, municipal development, recreation, tourism, mining exploration and open cast mining. The Cumulative Environmental Management Association (CEMA) was inaugurated as a non-profit association in April 2000, and includes 41 members from all sectors. Its major role is to ensure a sustainable ecosystem and to avoid any cumulative impacts on wildlife. Other work underway includes the study of soil and plant species diversity, and the effects of air emissions on human health, wildlife and vegetation. The bioaccumulation of heavy metals and their impacts on surface water and fish is also under consideration to ensure the quality and quantity of surface water and ground water. 3 figs.
Cumulative environmental management and the oil sands
Energy Technology Data Exchange (ETDEWEB)
NONE
2005-07-01
In response to concerns regarding the cumulative environmental impacts of oil sands development within the Athabasca oil sands deposit, the government of Alberta established a Regional Sustainable Development Strategy (RSDS) to balance development with environmental protection. The environmental issues identified through the RSDS were addressed by the Cumulative Environmental Management Association (CEMA). CEMA's boundary is the Wood Buffalo region of northeastern Alberta. It identifies existing and future environmental effects in the region and proposes recommendations to regulatory bodies for reducing environmental impacts associated with oil sands development. This presentation outlined some of the 55 stakeholder representatives of CEMA, including Alberta government departments associated with resource development, oil sand developers within the region, and Aboriginal communities and First Nations. These stakeholders provide input on sector priorities and agree on environmental thresholds. Established working groups also address technical and scientific research issues identified in the RSDS such as sustainable ecosystems; surface waters; trace metals and air contaminants; nitrogen oxides and sulphur dioxides; and land reclamation. To date, CEMA has submitted more than 50 reports and has made 4 major environmental recommendations for trace metal management, ecosystem management tools, a framework for acid deposition management, and a landscape design checklist. tabs., figs.
Higher Order Cumulants in Colorless Partonic Plasma
Cherif, S; Ladrem, M
2016-01-01
Any physical system considered to study the QCD deconfinement phase transition certainly has a finite volume, so the finite size effects are inevitably present. This renders the location of the phase transition and the determination of its order as an extremely difficult task, even in the simplest known cases. In order to identify and locate the colorless QCD deconfinement transition point in finite volume $T_{0}(V)$, a new approach based on the finite-size cumulant expansion of the order parameter and the $\\mathscr{L}_{m,n}$-Method is used.We have shown that both cumulants of higher order and their ratios, associated to the thermodynamical fluctuations of the order parameter, in QCD deconfinement phase transition behave in a particular enough way revealing pronounced oscillations in the transition region. The sign structure and the oscillatory behavior of these in the vicinity of the deconfinement phase transition point might be a sensitive probe and may allow one to elucidate their relation to the QCD phase...
Innovativeness, population size and cumulative cultural evolution.
Kobayashi, Yutaka; Aoki, Kenichi
2012-08-01
Henrich [Henrich, J., 2004. Demography and cultural evolution: how adaptive cultural processes can produce maladaptive losses-the Tasmanian case. Am. Antiquity 69, 197-214] proposed a model designed to show that larger population size facilitates cumulative cultural evolution toward higher skill levels. In this model, each newborn attempts to imitate the most highly skilled individual of the parental generation by directly-biased social learning, but the skill level he/she acquires deviates probabilistically from that of the exemplar (cultural parent). The probability that the skill level of the imitator exceeds that of the exemplar can be regarded as the innovation rate. After reformulating Henrich's model rigorously, we introduce an overlapping-generations analog based on the Moran model and derive an approximate formula for the expected change per generation of the highest skill level in the population. For large population size, our overlapping-generations model predicts a much larger effect of population size than Henrich's discrete-generations model. We then investigate by way of Monte Carlo simulations the case where each newborn chooses as his/her exemplar the most highly skilled individual from among a limited number of acquaintances. When the number of acquaintances is small relative to the population size, we find that a change in the innovation rate contributes more than a proportional change in population size to the cumulative cultural evolution of skill level.
1996-01-01
Interviews following the 1991 co-operation Agreement between the Department of Atomic Energy (DAE) of the Government of India and the European Organization for Nuclear Research (CERN) concerning the participation in the Large Hadron Collider Project (LHC) . With Chidambaram, R, Chairman, Atomic Energy Commission and Secretary, Department of Atomic Energy, Department of Atomic Energy (DAE) of the Government of India and Professor Llewellyn-Smith, Christopher H, Director-General, CERN.
Reichel, Jakob
2010-01-01
This book provides a stimulating and multifaceted picture of a rapidly developing field. The first part reviews fundamentals of atom chip research in tutorial style, while subsequent parts focus on the topics of atom-surface interaction, coherence on atom chips, and possible future directions of atom chip research. The articles are written by leading researchers in the field in their characteristic and individual styles.
Ion cumulation by conical cathode electrolysis.
Grishin, V G
2002-01-01
Results of solid-state sodium stearate electrolysis with conical and cylindrical cathodes is presented here. Both electric measurement and conical samples destruction can be explained if a stress developing inside the conical sample is much bigger than in the cylindrical case and there is its unlimited amplification along cone slopes. OTHER KEYWORDS: ion, current, solid, symmetry, cumulation, polarization, depolarization, ionic conductor,superionic conductor, ice, crystal, strain, V-center, V-centre, doped crystal, interstitial impurity, intrinsic color center, high pressure technology, Bridgman, anvil, experiment, crowdion, dielectric, proton, layer, defect, lattice, dynamics, electromigration, mobility, muon catalysis, concentration, doping, dopant, conductivity, pycnonuclear reaction, permittivity, dielectric constant, point defects, interstitials, polarizability, imperfection, defect centers, glass, epitaxy, sodium hydroxide, metallic substrate, crystallization, point, tip, susceptibility, ferroelectric, ...
[Cumulative trauma disorders: work or professional disease?].
de Carvalho, Marcus Vitor Diniz; Cavalcanti, Francisco Ivo Dantas; Soriano, Evelyne Pessoa; de Miranda, Hênio Ferreira
2009-06-01
This study aimed at reviewing the Brazilian legislation applied to occupational health. It refers to the diseases embodied in the Repetition Strain Injury (RSI) and Cumulative Trauma Disorders (CTD) regarded as work or professional diseases. This analysis allowed to perform the historical evolution of legislation concerning the issue, noting that the state of the art of regulation on RSI-CTD is anchored in specific regulation present in the Normative Instruction 98/2003, that establishes the diagnostic criteria and classification of RSI-CTD. It was concluded that according to the existing legislation in Brazil, the pathologies related to RSI-CTD are considered as work diseases and their legal effects are similar to the work-related accidents.
Blockade involving high- n, n ~ 300 , strontium Rydberg atoms
Yoshida, Shuhei; Burgdörfer, Joachim; Zhang, Xinyue; Dunning, F. Barry
2016-05-01
The blockade of high- n strontium n1F3 Rydberg states contained in a hot atomic beam is investigated both theoretically and experimentally. One difficulty in such experiments is that, once created, Rydberg atoms move out of the excitation volume reducing blockade effects. While the effects of such motion are apparent, the data provide strong evidence of blockade, consistent with theoretical predictions. Because of their relatively high angular momentum (L = 3) , a pair of n1F3 Rydberg atoms have many degenerate states whose degeneracy is removed by Rydberg-Rydberg interactions yielding a high density of states near the target energy. To evaluate the effect of blockade not only the energy shifts but also the modification of the oscillator strengths for excitation have to be taken into account. The n-scaling of the interactions and the importance of high-order multipoles will also be discussed. Research supported by the NSF and Robert A. Welch Foundation.
Polarization, alignment, and orientation in atomic collisions
Andersen, Nils
2017-01-01
This book covers polarization, alignment, and orientation effects in atomic collisions induced by electron, heavy particle, or photon impact. The first part of the book presents introductory chapters on light and particle polarization, experimental and computational methods, and the density matrix and state multipole formalism. Examples and exercises are included. The second part of the book deals with case studies of electron impact and heavy particle excitation, electron transfer, impact ionization, and autoionization. A separate chapter on photo-induced processes by new-generation light sources has been added. The last chapter discusses related topics and applications. Part III includes examples of charge clouds and introductory summaries of selected seminal papers of tutorial value from the early history of the field (1925 – 1975). The book is a significant update to the previous (first) edition, particularly in experimental and computational methods, the inclusion of key results obtained during the pas...
Energy Technology Data Exchange (ETDEWEB)
Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)
2015-01-22
The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.
Hirshfeld atom refinement for modelling strong hydrogen bonds.
Woińska, Magdalena; Jayatilaka, Dylan; Spackman, Mark A; Edwards, Alison J; Dominiak, Paulina M; Woźniak, Krzysztof; Nishibori, Eiji; Sugimoto, Kunihisa; Grabowsky, Simon
2014-09-01
High-resolution low-temperature synchrotron X-ray diffraction data of the salt L-phenylalaninium hydrogen maleate are used to test the new automated iterative Hirshfeld atom refinement (HAR) procedure for the modelling of strong hydrogen bonds. The HAR models used present the first examples of Z' > 1 treatments in the framework of wavefunction-based refinement methods. L-Phenylalaninium hydrogen maleate exhibits several hydrogen bonds in its crystal structure, of which the shortest and the most challenging to model is the O-H...O intramolecular hydrogen bond present in the hydrogen maleate anion (O...O distance is about 2.41 Å). In particular, the reconstruction of the electron density in the hydrogen maleate moiety and the determination of hydrogen-atom properties [positions, bond distances and anisotropic displacement parameters (ADPs)] are the focus of the study. For comparison to the HAR results, different spherical (independent atom model, IAM) and aspherical (free multipole model, MM; transferable aspherical atom model, TAAM) X-ray refinement techniques as well as results from a low-temperature neutron-diffraction experiment are employed. Hydrogen-atom ADPs are furthermore compared to those derived from a TLS/rigid-body (SHADE) treatment of the X-ray structures. The reference neutron-diffraction experiment reveals a truly symmetric hydrogen bond in the hydrogen maleate anion. Only with HAR is it possible to freely refine hydrogen-atom positions and ADPs from the X-ray data, which leads to the best electron-density model and the closest agreement with the structural parameters derived from the neutron-diffraction experiment, e.g. the symmetric hydrogen position can be reproduced. The multipole-based refinement techniques (MM and TAAM) yield slightly asymmetric positions, whereas the IAM yields a significantly asymmetric position.
DEFF Research Database (Denmark)
Krüger, Peter; Hofferberth, S.; Haller, E.
2005-01-01
Miniaturized potentials near the surface of atom chips can be used as flexible and versatile tools for the manipulation of ultracold atoms on a microscale. The full scope of possibilities is only accessible if atom-surface distances can be reduced to microns. We discuss experiments in this regime...
Simmonett, Andrew C.; Pickard, Frank C.; Schaefer, Henry F.; Brooks, Bernard R.
2014-05-01
Next-generation molecular force fields deliver accurate descriptions of non-covalent interactions by employing more elaborate functional forms than their predecessors. Much work has been dedicated to improving the description of the electrostatic potential (ESP) generated by these force fields. A common approach to improving the ESP is by augmenting the point charges on each center with higher-order multipole moments. The resulting anisotropy greatly improves the directionality of the non-covalent bonding, with a concomitant increase in computational cost. In this work, we develop an efficient strategy for enumerating multipole interactions, by casting an efficient spherical harmonic based approach within a particle mesh Ewald (PME) framework. Although the derivation involves lengthy algebra, the final expressions are relatively compact, yielding an approach that can efficiently handle both finite and periodic systems without imposing any approximations beyond PME. Forces and torques are readily obtained, making our method well suited to modern molecular dynamics simulations.
Kneller, Gerald R.; Chevrot, Guillaume
2012-12-01
This paper addresses the question to which extent anisotropic atomic motions in proteins impact angular-averaged incoherent neutron scattering intensities, which are typically recorded for powder samples. For this purpose, the relevant correlation functions are represented as multipole series in which each term corresponds to a different degree of intrinsic motional anisotropy. The approach is illustrated by a simple analytical model and by a simulation-based example for lysozyme, considering in both cases the elastic incoherent structure factor. The second example shows that the motional anisotropy of the protein atoms is considerable and contributes significantly to the scattering intensity.
Long and Short Term Cumulative Structural Priming Effects.
Kaschak, Michael P; Kutta, Timothy J; Coyle, Jacqueline M
We present six experiments that examine cumulative structural priming effects (i.e., structural priming effects that accumulate across many utterances). Of particular interest is whether (1) cumulative priming effects transfer across language production tasks and (2) the transfer of cumulative priming effects across tasks persists over the course of a week. Our data suggest that cumulative structural priming effects do transfer across language production tasks (e.g., from written stem completion to picture description, and from picture description to written stem completion), but only when both tasks are presented in the same experimental session. When cumulative priming effects are established in one task, and the second (changed) task is not presented until a week later, the cumulative priming effects are not observed.
Why Veterinary Medical Educators Should Embrace Cumulative Final Exams.
Royal, Kenneth D
2017-01-03
The topic of cumulative final examinations often elicits polarizing opinions from veterinary medical educators. While some faculty prefer cumulative finals, there are many who perceive these types of examinations as problematic. Specifically, faculty often cite cumulative examinations are more likely to cause students' greater stress, which may in turn result in negative student evaluations of teaching. Cumulative finals also restrict the number of items one may present to students on most recent material. While these cited disadvantages may have some merit, the advantages of cumulative examinations far exceed the disadvantages. The purpose of this article is to discuss the advantages of cumulative examinations with respect to learning evidence, grade/score validity, fairness issues, and implications for academic policy.
Multipole generator wind energy converter without gearbox and with variable speed
Energy Technology Data Exchange (ETDEWEB)
Wortmann, B.; Hansen, L.H.
2000-01-01
The idea of this industrial research project was a totally new concept of WTG for NEG Micon A/S. The result has been a multiple range of concepts. Siemens realised a complete design and construction of a multipole PMG generator. However, it was soon recognised that the multipole synchronous PMG concept of Siemens was too expensive. The change to a WRG concept improved the situation. However, it is still doubtful if an economic feasible solution can be obtained for use in a WTG. Evidently, it is necessary looking on other concepts of synchronous generators for wind energy conversion. One way of verifying the economic feasibility was to clarify uncertainty about necessary support technologies. Two support technologies were investigated: variable speed control and blade turning system. Both systems turned out to be interesting concepts on their own. A complete specification of the safety and control strategy for variable speed was developed within this project. The strategy was implemented onthe test WTG on the test site of Risoe National Laboratory. The test set-up is very flexible and is based on the use of a Siemens IGBT Frequency Converter. The WTG can be operated as a conventional stall regulated WTG or as variable speed WTG. For calculation purpose HawC has been enlarged as a first step by the possibility to simulate a stall controlled WTG equipped with an asynchronous generator. Various tests on loads and electrical grid quality can be realised for this case. The second element of the project was the blade turning system, A full scale test set-up made a lifecycle test program possible. Many new tools and valuable knowledge were gathered and developed. The FLEX 4 load calculation program has been adapted to active stall operation. The results of the project were very promising. Today, this research forms the basis for NEG Migon A/S active stall concept on the NM 2000. The project has broaden ed NEG Micon A/S horizon for new control strategies. New areas for
Analysis of experimental data on correlations between cumulative particles
Energy Technology Data Exchange (ETDEWEB)
Vlasov, A.V.; Doroshkevich, E.A.; Leksin, G.A. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation)] [and others
1995-04-01
Experimental data on correlations between cumulative particles are analyzed. A space-time and energy-transfer pattern of hadron-nucleus interaction based on both correlation data and data on the inclusive spectra of cumulative particles is considered. A new variable that is convenient for describing the production of cumulative particles is proposed using the concept of symmetry between the one-particle and multiparticle distributions. 32 refs., 9 figs., 1 tab.
Moroz, Alexander
2009-01-01
The contribution of higher-order multipoles to radiative and non-radiative decay of a single dipole emitter close to a spherical metallic nanoparticle is re-examined. Taking a Ag spherical nanoparticle (AgNP) with the radius of 5 nm as an example, a significant contribution (between 50% and 101% of the total value) of higher-order multipoles to non-radiative rates is found even at the emitter distance of 5 nm from the AgNP surface. On the other hand, the higher-order multipole contribution to radiative rates is negligible. Consequently, a dipole-dipole approximation can yield only an upper bound on the apparent quantum yield. In contrast, the non-radiative rates calculated with the quasistatic Gersten and Nitzan method are found to be in much better agreement with exact electrodynamic results. Finally, the size corrected metal dielectric function is shown to decrease the non-radiative rates near the dipolar surface plasmon resonance.
Völlinger, C
2000-01-01
This note presents a scheme for compensating the persistent current multipole errors of the LHC dipoles by making the coil protection sheets from soft magnetic material of 0.5 mm thickness. The material properties assumed in this study are those of iron sheets with a very low content of impurities (99.99% pure Fe). The non-linearities in the upramp cycle on the b3 multipole component can be reduced by the factor of four (while decreasing the b5 variation by the factor of two. Using sheets of slightly different thicknesses offers a tuning possibility for the series magnet coils and can compensate deviations arising from cables of different suppliers. The calculation method is based on a semi-analytical hysteresis model for hard superconductors and an M(B) - iteration using the method of coupled boundary elements - finite elements (BEM - FEM). It is now possible to compute persistent current multipole errors of geometries with arbitrarily shaped iron yokes and thin layers of soft magnetic material such as tunin...
STEM-EELS analysis of multipole surface plasmon modes in symmetry-broken AuAg nanowire dimers
Schubert, Ina; Sigle, Wilfried; van Aken, Peter A.; Trautmann, Christina; Toimil-Molares, Maria Eugenia
2015-03-01
Surface plasmon coupling in nanowires separated by small gaps generates high field enhancements at the position of the gap and is thus of great interest for sensing applications. It is known that the nanowire dimensions and in particular the symmetry of the structures has strong influence on the plasmonic properties of the dimer structure. Here, we report on multipole surface plasmon coupling in symmetry-broken AuAg nanowire dimers. Our dimers, consisting of two nanowires with different lengths and separated by gaps of only 10 to 30 nm, were synthesized by pulsed electrochemical deposition in ion track-etched polymer templates. Electron energy-loss spectroscopy in scanning transmission electron microscopy allows us to resolve up to nine multipole order surface plasmon modes of these dimers spectrally separated from each other. The spectra evidence plasmon coupling between resonances of different multipole order, resulting in the generation of additional plasmonic modes. Since such complex structures require elaborated synthesis techniques, dimer structures with complex composition, morphology and shape are created. We demonstrate that finite element simulations on pure Au dimers can predict the generated resonances in the fabricated structures. The excellent agreement of our experiment on AuAg dimers with finite integration simulations using CST microwave studio manifests great potential to design complex structures for sensing applications.
DDEC6: A Method for Computing Even-Tempered Net Atomic Charges in Periodic and Nonperiodic Materials
Manz, Thomas A
2015-01-01
Net atomic charges (NACs) are widely used in all chemical sciences to concisely summarize key information about the partitioning of electrons among atoms in materials. Although widely used, there is currently no atomic population analysis method suitable for being used as a default method in quantum chemistry programs. To address this challenge, we introduce a new atoms-in-materials method with the following nine properties: (1) exactly one electron distribution is assigned to each atom, (2) core electrons are assigned to the correct host atom, (3) NACs are formally independent of the basis set type because they are functionals of the total electron distribution, (4) the assigned atomic electron distributions give an efficiently converging polyatomic multipole expansion, (5) the assigned NACs usually follow Pauling scale electronegativity trends, (6) NACs for a particular element have good transferability among different conformations that are equivalently bonded, (7) the assigned NACs are chemically consiste...
Analysis of Memory Codes and Cumulative Rehearsal in Observational Learning
Bandura, Albert; And Others
1974-01-01
The present study examined the influence of memory codes varying in meaningfulness and retrievability and cumulative rehearsal on retention of observationally learned responses over increasing temporal intervals. (Editor)
Continuously Cumulating Meta-Analysis and Replicability.
Braver, Sanford L; Thoemmes, Felix J; Rosenthal, Robert
2014-05-01
The current crisis in scientific psychology about whether our findings are irreproducible was presaged years ago by Tversky and Kahneman (1971), who noted that even sophisticated researchers believe in the fallacious Law of Small Numbers-erroneous intuitions about how imprecisely sample data reflect population phenomena. Combined with the low power of most current work, this often leads to the use of misleading criteria about whether an effect has replicated. Rosenthal (1990) suggested more appropriate criteria, here labeled the continuously cumulating meta-analytic (CCMA) approach. For example, a CCMA analysis on a replication attempt that does not reach significance might nonetheless provide more, not less, evidence that the effect is real. Alternatively, measures of heterogeneity might show that two studies that differ in whether they are significant might have only trivially different effect sizes. We present a nontechnical introduction to the CCMA framework (referencing relevant software), and then explain how it can be used to address aspects of replicability or more generally to assess quantitative evidence from numerous studies. We then present some examples and simulation results using the CCMA approach that show how the combination of evidence can yield improved results over the consideration of single studies.
Casimir-Polder forces on atoms in the presence of magnetoelectronic bodies
Energy Technology Data Exchange (ETDEWEB)
Buhmann, S.Y.
2007-07-05
In this work, the CP force between a single neutral atom or molecule and neutral magnetoelectric bodies is studied. The focus lies on the pure vacuum CP force, i.e., the electromagnetic field is in general understood to be in its ground state. Furthermore, we assume that the atom-body separation is sufficiently large to ensure that the atom is adequately characterised as an electric dipole, while the body can be described by its macroscopic magnetoelectric properties; and that repulsive exchange forces due to the overlap between the electronic wave functions of the atom and the bodies can be neglected. Interactions due to non-vanishing net charges, permanent electric dipole moments, magnetisability, quadrupole (or higher multipole) polarisabilities of the atom and those resulting from non-local or anisotropic magnetoelectric properties of the bodies are ignored. (orig.)
Strong coupling effects between a meta-atom and MIM nanocavity
Directory of Open Access Journals (Sweden)
San Chen
2012-09-01
Full Text Available In this paper, we investigate the strong coupling effects between a meta-atom and a metal-insulator-metal (MIM nanocavity. By changing the meta-atom sizes, we achieve the meta-atomic electric dipole, quadrupole or multipole interaction with the plasmonic nanocavity, in which characteristic anticrossing behaviors demonstrate the occurrence of the strong coupling. The various interactions present obviously different splitting values and behaviors of dependence on the meta-atomic position. The largest Rabi-type splittings, about 360.0 meV and 306.1 meV, have been obtained for electric dipole and quadrupole interaction, respectively. We attribute the large splitting to the highly-confined cavity mode and the large transition dipole of the meta-atom. Also the Rabi-type oscillation in time domain is given.
Low loss pole configuration for multi-pole homopolar magnetic bearings
Blumenstock, Kenneth A. (Inventor); Hakun, Claef F. (Inventor)
2001-01-01
A new pole configuration for multi-pole homopolar bearings proposed in this invention reduces rotational losses caused by eddy-currents generated when non-uniform flux distributions exist along the rotor surfaces. The new homopolar magnetic bearing includes a stator with reduced pole-to-pole and exhibits a much more uniform rotor flux than with large pole-to-pole gaps. A pole feature called a pole-link is incorporated into the low-loss poles to provide a uniform pole-to-pole gap and a controlled path for pole-to-pole flux. In order to implement the low-loss pole configuration of magnetic bearings with small pole-to-pole gaps, a new stator configuration was developed to facilitate installation of coil windings. The stator was divided into sector shaped pieces, as many pieces as there are poles. Each sector-shaped pole-piece can be wound on a standard coil winding machine, and it is practical to wind precision layer wound coils. To achieve maximum actuation efficiency, it is desirable to use all the available space for the coil formed by the natural geometric configuration. Then, the coils can be wound in a tapered shape. After winding, the sectored-pole-pieces are installed into and fastened by bonding or other means, to a ring of material which encloses the sectored-pole-pieces, forming a complete stator.
Combining the multilevel fast multipole method with the uniform geometrical theory of diffraction
Directory of Open Access Journals (Sweden)
A. Tzoulis
2005-01-01
Full Text Available The presence of arbitrarily shaped and electrically large objects in the same environment leads to hybridization of the Method of Moments (MoM with the Uniform Geometrical Theory of Diffraction (UTD. The computation and memory complexity of the MoM solution is improved with the Multilevel Fast Multipole Method (MLFMM. By expanding the k-space integrals in spherical harmonics, further considerable amount of memory can be saved without compromising accuracy and numerical speed. However, until now MoM-UTD hybrid methods are restricted to conventional MoM formulations only with Electric Field Integral Equation (EFIE. In this contribution, a MLFMM-UTD hybridization for Combined Field Integral Equation (CFIE is proposed and applied within a hybrid Finite Element - Boundary Integral (FEBI technique. The MLFMM-UTD hybridization is performed at the translation procedure on the various levels of the MLFMM, using a far-field approximation of the corresponding translation operator. The formulation of this new hybrid technique is presented, as well as numerical results.
Collective multipole excitations based on correlated realistic nucleon-nucleon interactions
Energy Technology Data Exchange (ETDEWEB)
Paar, N. [Zagreb Univ. (Croatia). Fac. of Science, Physics Dept.; Papakonstantinou, P.; Hergert, H.; Roth, R. [Technische Univ. Darmstadt (Germany). Inst. fuer Kernphysik
2006-05-24
We investigate collective multipole excitations for closed shell nuclei from {sup 16}O to {sup 208}Pb using correlated realistic nucleon-nucleon interactions in the framework of the random phase approximation (RPA). The dominant short-range central and tensor correlations a re treated explicitly within the Unitary Correlation Operator Method (UCOM), which provides a phase-shift equivalent correlated interaction VUCOM adapted to simple uncorrelated Hilbert spaces. The same unitary transformation that defines the correlated interaction is used to derive correlated transition operators. Using VUCOM we solve the Hartree-Fock problem and employ the single-particle states as starting point for the RPA. By construction, the UCOM-RPA is fully self-consistent, i.e. the same correlated nucleon-nucleon interact ion is used in calculations of the HF ground state and in the residual RPA interaction. Consequently, the spurious state associated with the center-of-mass motion is properly removed and the sum-rules are exhausted within {+-}3%. The UCOM-RPA scheme results in a collective character of giant monopole, dipole, and quadrupole resonances in closed-shell nuclei across the nuclear chart. For the isoscalar giant monopole resonance, the resonance energies are in agreement with experiment hinting at a reasonable compressibility. However, in the 1{sup -} and 2{sup +} channels the resonance energies are overestimated due to missing long-range correlations and three-body contributions. (orig.)
Application of Fast Multipole Methods to the NASA Fast Scattering Code
Dunn, Mark H.; Tinetti, Ana F.
2008-01-01
The NASA Fast Scattering Code (FSC) is a versatile noise prediction program designed to conduct aeroacoustic noise reduction studies. The equivalent source method is used to solve an exterior Helmholtz boundary value problem with an impedance type boundary condition. The solution process in FSC v2.0 requires direct manipulation of a large, dense system of linear equations, limiting the applicability of the code to small scales and/or moderate excitation frequencies. Recent advances in the use of Fast Multipole Methods (FMM) for solving scattering problems, coupled with sparse linear algebra techniques, suggest that a substantial reduction in computer resource utilization over conventional solution approaches can be obtained. Implementation of the single level FMM (SLFMM) and a variant of the Conjugate Gradient Method (CGM) into the FSC is discussed in this paper. The culmination of this effort, FSC v3.0, was used to generate solutions for three configurations of interest. Benchmarking against previously obtained simulations indicate that a twenty-fold reduction in computational memory and up to a four-fold reduction in computer time have been achieved on a single processor.
Multipole expansion of Green's function for guided waves in a transversely isotropic plate
Energy Technology Data Exchange (ETDEWEB)
Lee, Heung Son; Kim, Yoon Young [Seoul National University, Seoul (Korea, Republic of)
2015-05-15
The multipole expansion of Green's function in a transversely isotropic plate is derived based on the eigenfunction expansion method. For the derivation, Green's function is expressed in a bilinear form composed of the regular and singular Lamb-type (or shear-horizontal) wave eigenfunctions. The specific form of the derived Green's function facilitates the handling of general scattering problems in an elastic plate when numerical methods such as the methods of the null-field integral equations are employed. In the derivation, the integral transform of an arbitrary guided wave field is first constructed by the Lamb-type and shear horizontal wave eigenfunctions that work as the kernel functions. After showing that the thickness-dependent parts of the eigenfunctions are orthogonal to each other in the transformed space, Green's function is explicitly derived by using the orthogonality. As an application of the derived Green's function, a scattering problem is solved by the transition matrix method.
Some Physical Consequences of Abrupt Changes in the Multipole Moments of a Gravitating Body
Barrabès, C; Hogan, P A
1997-01-01
The Barrabès-Israel theory of light-like shells in General Relativity= is used to show explicitly that in general a light-like shell is accompanied= by an impulsive gravitational wave. The gravitational wave is identified by = its Petrov Type N contribution to a Dirac delta-function term in the Weyl conformal curvature tensor (with the delta-function singular on the null hypersurface history of the wave and shell). An example is described in w= hich an asymptotically flat static vacuum Weyl space-time experiences a sudden change across a null hypersurface in the multipole moments of its isolate= d axially symmetric source. A light-like shell and an impulsive gravitation= al wave are identified, both having the null hypersurface as history. The stress-energy in the shell is dominated (at large distance from the sourc= e) by the jump in the monopole moment (the mass) of the source with the jump in= the quadrupole moment mainly responsible for the stress being anisotropic. Th= e gravitational wave owes its exis...
Oberberg, Moritz; Styrnoll, Tim; Ries, Stefan; Bienholz, Stefan; Awakowicz, Peter
2015-09-01
Reactive sputter processes are used for the deposition of hard, wear-resistant and non-corrosive ceramic layers such as aluminum oxide (Al2O3) . A well known problem is target poisoning at high reactive gas flows, which results from the reaction of the reactive gas with the metal target. Consequently, the sputter rate decreases and secondary electron emission increases. Both parameters show a non-linear hysteresis behavior as a function of the reactive gas flow and this leads to process instabilities. This work presents a new control method of Al2O3 deposition in a multiple frequency CCP (MFCCP) based on plasma parameters. Until today, process controls use parameters such as spectral line intensities of sputtered metal as an indicator for the sputter rate. A coupling between plasma and substrate is not considered. The control system in this work uses a new plasma diagnostic method: The multipole resonance probe (MRP) measures plasma parameters such as electron density by analyzing a typical resonance frequency of the system response. This concept combines target processes and plasma effects and directly controls the sputter source instead of the resulting target parameters.
Stability of spherically symmetric, charged black holes and multipole moments for stationary systems
Energy Technology Data Exchange (ETDEWEB)
Gursel, H.Y.
1983-01-01
This dissertation is written in two parts. Part I deals with the question of stability of a spherically symmetric, charged black hole against scalar, electromagnetic, and gravitational perturbations. It consists of two papers written in collaboration with Igor D. Novikov, Vernon D. Sandberg and A.A. Starobinsky. In these papers the dynamical evolution of these perturbations on the interior of a Reissner-Nordstrom black hole is described. The instability of the hole's Cauchy horizon is discussed in detail in terms of the energy densities of the test fields as measured by a freely falling observer approaching the Cauchy horizon. It is concluded that the Cauchy horizon of the analytically extended Reissner-Nordstrom solution is highly unstable and not a physical feature of a realistic gravitational collapse. Part II of this dissertation addresses two problems closely connected with multipole structure of stationary, asymptotically flat spacetimes. It consists of two papers written in collaboration with Kip S. Thorne. The first one shows the equivalence of the moments defined by Kip S. Thorne and the moments defined by Robert Geroch and Richard Hansen. The second proves a conjecture by Kip S. Thorne: In the limit of ''slow'' motion, general relativistic gravity produces no changes whatsoever in the classical Euler equations of rigid body motion. This conjecture is proved by giving an algorithm for generating rigidly rotating solutions of Einstein's equation from nonrotating, static solutions.
Inexact Krylov iterations and relaxation strategies with fast-multipole boundary element method
Layton, Simon K
2015-01-01
Boundary element methods produce dense linear systems that can be accelerated via multipole expansions. Solved with Krylov methods, this implies computing the matrix-vector products within each iteration with some error, at an accuracy controlled by the order of the expansion, $p$. We take advantage of a unique property of Krylov iterations that allow lower accuracy of the matrix-vector products as convergence proceeds, and propose a relaxation strategy based on progressively decreasing $p$. Via extensive numerical tests, we show that the relaxed Krylov iterations converge with speed-ups of between 2x and 4x for Laplace problems and between 3.5x and 4.5x for Stokes problems. We include an application to Stokes flow around red blood cells, computing with up to 64 cells and problem size up to 131k boundary elements and nearly 400k unknowns. The study was done with an in-house multi-threaded C++ code, on a quad-core CPU.
Revision of FMM-Yukawa: An adaptive fast multipole method for screened Coulomb interactions
Zhang, Bo; Huang, Jingfang; Pitsianis, Nikos P.; Sun, Xiaobai
2010-12-01
FMM-YUKAWA is a mathematical software package primarily for rapid evaluation of the screened Coulomb interactions of N particles in three dimensional space. Since its release, we have revised and re-organized the data structure, software architecture, and user interface, for the purpose of enabling more flexible, broader and easier use of the package. The package and its documentation are available at http://www.fastmultipole.org/, along with a few other closely related mathematical software packages. New version program summaryProgram title: FMM-Yukawa Catalogue identifier: AEEQ_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEQ_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPL 2.0 No. of lines in distributed program, including test data, etc.: 78 704 No. of bytes in distributed program, including test data, etc.: 854 265 Distribution format: tar.gz Programming language: FORTRAN 77, FORTRAN 90, and C. Requires gcc and gfortran version 4.4.3 or later Computer: All Operating system: Any Classification: 4.8, 4.12 Catalogue identifier of previous version: AEEQ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 180 (2009) 2331 Does the new version supersede the previous version?: Yes Nature of problem: To evaluate the screened Coulomb potential and force field of N charged particles, and to evaluate a convolution type integral where the Green's function is the fundamental solution of the modified Helmholtz equation. Solution method: The new version of fast multipole method (FMM) that diagonalizes the multipole-to-local translation operator is applied with the tree structure adaptive to sample particle locations. Reasons for new version: To handle much larger particle ensembles, to enable the iterative use of the subroutines in a solver, and to remove potential contention in assignments for parallelization. Summary of revisions: The software package FMM-Yukawa has been
MULTIPOLE GRAVITATIONAL LENSING AND HIGH-ORDER PERTURBATIONS ON THE QUADRUPOLE LENS
Energy Technology Data Exchange (ETDEWEB)
Chu, Z.; Lin, W. P. [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Li, G. L. [Purple Mountain Observatory, 2 West Beijing Road, Nanjing 210008 (China); Kang, X., E-mail: chuzhe@shao.ac.cn, E-mail: linwp@shao.ac.cn [Partner Group of MPI for Astronomy, Purple Mountain Observatory, 2 West Beijing Road, Nanjing 210008 (China)
2013-03-10
An arbitrary surface mass density of the gravitational lens can be decomposed into multipole components. We simulate the ray tracing for the multipolar mass distribution of the generalized Singular Isothermal Sphere model based on deflection angles, which are analytically calculated. The magnification patterns in the source plane are then derived from an inverse shooting technique. As has been found, the caustics of odd mode lenses are composed of two overlapping layers for some lens models. When a point source traverses this kind of overlapping caustics, the image numbers change by {+-}4, rather than {+-}2. There are two kinds of caustic images. One is the critical curve and the other is the transition locus. It is found that the image number of the fold is exactly the average value of image numbers on two sides of the fold, while the image number of the cusp is equal to the smaller one. We also focus on the magnification patterns of the quadrupole (m = 2) lenses under the perturbations of m = 3, 4, and 5 mode components and found that one, two, and three butterfly or swallowtail singularities can be produced, respectively. With the increasing intensity of the high-order perturbations, the singularities grow up to bring sixfold image regions. If these perturbations are large enough to let two or three of the butterflies or swallowtails make contact, then eightfold or tenfold image regions can be produced as well. The possible astronomical applications are discussed.
Cumulative Effect of Depression on Dementia Risk
Directory of Open Access Journals (Sweden)
J. Olazarán
2013-01-01
Full Text Available Objective. To analyze a potential cumulative effect of life-time depression on dementia and Alzheimer’s disease (AD, with control of vascular factors (VFs. Methods. This study was a subanalysis of the Neurological Disorders in Central Spain (NEDICES study. Past and present depression, VFs, dementia status, and dementia due to AD were documented at study inception. Dementia status was also documented after three years. Four groups were created according to baseline data: never depression (nD, past depression (pD, present depression (prD, and present and past depression (prpD. Logistic regression was used. Results. Data of 1,807 subjects were investigated at baseline (mean age 74.3, 59.3% women, and 1,376 (81.6% subjects were evaluated after three years. The prevalence of dementia at baseline was 6.7%, and dementia incidence was 6.3%. An effect of depression was observed on dementia prevalence (OR [CI 95%] 1.84 [1.01–3.35] for prD and 2.73 [1.08–6.87] for prpD, and on dementia due to AD (OR 1.98 [0.98–3.99] for prD and OR 3.98 [1.48–10.71] for prpD (fully adjusted models, nD as reference. Depression did not influence dementia incidence. Conclusions. Present depression and, particularly, present and past depression are associated with dementia at old age. Multiple mechanisms, including toxic effect of depression on hippocampal neurons, plausibly explain these associations.
Cumulative social disadvantage and child health.
Bauman, Laurie J; Silver, Ellen J; Stein, Ruth E K
2006-04-01
Disparities in child health are a major public health concern. However, it is unclear whether these are predominantly the result of low income, race, or other social risk factors that may contribute to their health disadvantage. Although others have examined the effects of the accumulation of risk factors, this methodology has not been applied to child health. We tested 4 social risk factors (poverty, minority race/ethnicity, low parental education, and not living with both biological parents) to assess whether they have cumulative effects on child health and examined whether access to health care reduced health disparities. We analyzed data on 57,553 children low parental education, and single-parent household) were consistently associated with child health. These were summed, generating the Social Disadvantage Index (range: 0-3). A total of 43.6% of children had no social disadvantages, 30.8% had 1, 15.6% had 2, and 10.0% had all 3. Compared with those with no social disadvantages, the odds ratios (ORs) of being in "good, fair, or poor health" (versus "excellent or very good") were 1.95 for 1 risk, 3.22 for 2 risks, and 4.06 for 3 risks. ORs of having a chronic condition increased from 1.25 (1 risk) to 1.60 (2 risks) to 2.11 (3 risks). ORs for activity limitation were 1.51 (1 risk) to 2.14 (2 risks) and 2.88 (3 risks). Controlling for health insurance did not affect these findings. The accumulation of social disadvantage among children was strongly associated with poorer child health and having insurance did not reduce the observed health disparities.
Born, Max
1989-01-01
The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.
Imboden, Matthias; Pardo, Flavio; Bolle, Cristian; Han, Han; Tareen, Ammar; Chang, Jackson; Christopher, Jason; Corman, Benjamin; Bishop, David
2013-03-01
Here we present a MEMS based method to fabricate devices with a small number of atoms. In standard semiconductor fabrication, a large amount of material is deposited, after which etching removes what is not wanted. This technique breaks down for structures that approach the single atom limit, as it is inconceivable to etch away all but one atom. What is needed is a bottom up method with single or near single atom precision. We demonstrate a MEMS device that enables nanometer position controlled deposition of gold atoms. A digitally driven plate is swept as a flux of gold atoms passes through an aperture. Appling voltages on four comb capacitors connected to the central plate by tethers enable nanometer lateral precision in the xy plane over 15x15 sq. microns. Typical MEMS structures have manufacturing resolutions on the order of a micron. Using a FIB it is possible to mill apertures as small as 10 nm in diameter. Assuming a low incident atomic flux, as well as an integrated MEMS based shutter with microsecond response time, it becomes possible to deposit single atoms. Due to their small size and low power consumption, such nano-printers can be mounted directly in a cryogenic system at ultrahigh vacuum to deposit clean quench condensed metallic structures.
Long-range interactions of excited He atoms with ground-state noble-gas atoms
Zhang, J.-Y.
2013-10-09
The dispersion coefficients C6, C8, and C10 for long-range interactions of He(n1,3S) and He(n1,3P), 2≤n≤10, with the ground-state noble-gas atoms Ne, Ar, Kr, and Xe are calculated by summing over the reduced matrix elements of multipole transition operators. The large-n expansions for the sums over the He oscillator strength divided by the corresponding transition energy are presented for these series. Using the expansions, the C6 coefficients for the systems involving He(131,3S) and He(131,3P) are calculated and found to be in good agreement with directly calculated values.
A Framework for Treating Cumulative Trauma with Art Therapy
Naff, Kristina
2014-01-01
Cumulative trauma is relatively undocumented in art therapy practice, although there is growing evidence that art therapy provides distinct benefits for resolving various traumas. This qualitative study proposes an art therapy treatment framework for cumulative trauma derived from semi-structured interviews with three art therapists and artistic…
Cumulative Effects of Human Activities on Marine Mammal Populations
2015-09-30
1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Cumulative Effects of Human Activities on Marine Mammal ...marine mammals . OBJECTIVES The National Academies of Sciences, Engineering, and Medicine has convened a volunteer committee that will...Review the present scientific understanding of cumulative effects of anthropogenic stressors on marine mammals with a focus on anthropogenic sound
A Framework for Treating Cumulative Trauma with Art Therapy
Naff, Kristina
2014-01-01
Cumulative trauma is relatively undocumented in art therapy practice, although there is growing evidence that art therapy provides distinct benefits for resolving various traumas. This qualitative study proposes an art therapy treatment framework for cumulative trauma derived from semi-structured interviews with three art therapists and artistic…
Cumulative Estrogen Exposure and Prospective Memory in Older Women
Hesson, Jacqueline
2012-01-01
This study looked at cumulative lifetime estrogen exposure, as estimated with a mathematical index (Index of Cumulative Estrogen Exposure (ICEE)) that included variables (length of time on estrogen therapy, age at menarche and menopause, postmenopausal body mass index, time since menopause, nulliparity and duration of breastfeeding) known to…
Lattice QCD results on cumulant ratios at freeze-out
Karsch, Frithjof
2016-01-01
Ratios of cumulants of net proton-number fluctuations measured by the STAR Collaboration show strong deviations from a skellam distribution, which should describe thermal properties of cumulant ratios, if proton-number fluctuations are generated in equilibrium and a hadron resonance gas (HRG) model would provide a suitable description of thermodynamics at the freeze-out temperature. We present some results on sixth order cumulants entering the calculation of the QCD equation of state at non-zero values of the baryon chemical potential (mu_B) and discuss limitations on the applicability of HRG thermodynamics deduced from a comparison between QCD and HRG model calculations of cumulants of conserved charge fluctuations. We show that basic features of the $\\mu_B$-dependence of skewness and kurtosis ratios of net proton-number fluctuations measured by the STAR Collaboration resemble those expected from a O(mu_B^2) QCD calculation of the corresponding net baryon-number cumulant ratios.
A new family of cumulative indexes for measuring scientific performance.
Directory of Open Access Journals (Sweden)
Marcin Kozak
Full Text Available In this paper we propose a new family of cumulative indexes for measuring scientific performance which can be applied to many metrics, including h index and its variants (here we apply it to the h index, h(2 index and Google Scholar's i10 index. These indexes follow the general principle of repeating the index calculation for the same publication set. Using bibliometric data and reviewer scores for accepted and rejected fellowship applicants we examine how valid the cumulative variant is compared to the original variant. These analyses showed that the cumulative indexes result in higher correlations with the reviewer scores than their original variants. Thus, the cumulative indexes better reflect the assessments by peers than the original variants and are useful extensions of the original indexes. In contrast to many other measures of scientific performance proposed up to now, the cumulative indexes seem not only to be effective, but they are also easy to understand and calculate.
Indian Academy of Sciences (India)
MIN-T SAI LAI; SHIH-CHIH CHEN
2016-05-01
In this paper, a bivariate replacement policy (n, T) for a cumulative shock damage process is presented that included the concept of cumulative repair cost limit. The arrival shocks can be divided into two kinds of shocks. Each type-I shock causes a random amount of damage and these damages are additive. When the total damage exceeds a failure level, the system goes into serious failure. Type-II shock causes the system into minor failure and such a failure can be corrected by minimal repair. When a minor failure occurs, the repaircost will be evaluated and minimal repair is executed if the accumulated repair cost is less than a predetermined limit L. The system is replaced at scheduled time T, at n-th minor failure, or at serious failure. The long-term expected cost per unit time is derived using the expected costs as the optimality criterion. The minimum-cost policy is derived, and existence and uniqueness of the optimal n* and T* are proved. This bivariate optimal replacement policy (n, T) is showed to be better than the optimal T* and the optimal n* policy.
Longhi Games, Internal Reservoirs, and Cumulate Porosity
Morse, S. A.
2009-05-01
Fe in plagioclase at an early age, T-rollers (or not) on the Di-Trid boundary in Fo-Di-Sil, the mantle solidus, origins of anorthosites, esoteric uses of Schreinemakers rules and many more topics are all fresh and pleasant memories of John Longhi's prolific and creative work. The Fram-Longhi experimental effect of pressure on plagioclase partitioning with liquid in mafic rocks became essential to an understanding of multiphase Rayleigh fractionation of plagioclase in big layered intrusions. Only by using the pressure effect could I find a good equation through the data for the Kiglapait intrusion, and that result among others required the existence with probability 1.0 of an internal reservoir (Morse, JPet 2008). Knowledge of cumulate porosity is a crucial key to the understanding of layered igneous rocks. We seek both the initial (inverse packing fraction) and residual porosity to find the time and process path from sedimentation to solidification. In the Kiglapait Lower Zone we have a robust estimate of mean residual porosity from the modes of the excluded phases augite, oxides, sulfide, and apatite. To this we apply the maximum variance of plagioclase composition (the An range) to find an algorithm that extends through the Upper Zone and to other intrusions. Of great importance is that all these measurements were made in grain mounts concentrated from typically about 200 g of core or hand specimen, hence the represented sample volume is thousands of times greater than for a thin section. The resulting distribution and scatter of the An range is novel and remarkable. It is V-shaped in the logarithmic representation of stratigraphic height, running from about 20 mole % at both ends (base to top of the Layered Series) to near-zero at 99 PCS. The intercept of the porosity-An range relation gives An range = 3.5 % at zero residual porosity. Petrographic analysis reveals that for PCS less than 95 and greater than 99.9, the An range is intrinsic, i.e. pre-cumulus, for
Multilevel fast multipole algorithm for elastic wave scattering by large three-dimensional objects
Tong, Mei Song; Chew, Weng Cho
2009-02-01
Multilevel fast multipole algorithm (MLFMA) is developed for solving elastic wave scattering by large three-dimensional (3D) objects. Since the governing set of boundary integral equations (BIE) for the problem includes both compressional and shear waves with different wave numbers in one medium, the double-tree structure for each medium is used in the MLFMA implementation. When both the object and surrounding media are elastic, four wave numbers in total and thus four FMA trees are involved. We employ Nyström method to discretize the BIE and generate the corresponding matrix equation. The MLFMA is used to accelerate the solution process by reducing the complexity of matrix-vector product from O(N2) to O(NlogN) in iterative solvers. The multiple-tree structure differs from the single-tree frame in electromagnetics (EM) and acoustics, and greatly complicates the MLFMA implementation due to the different definitions for well-separated groups in different FMA trees. Our Nyström method has made use of the cancellation of leading terms in the series expansion of integral kernels to handle hyper singularities in near terms. This feature is kept in the MLFMA by seeking the common near patches in different FMA trees and treating the involved near terms synergistically. Due to the high cost of the multiple-tree structure, our numerical examples show that we can only solve the elastic wave scattering problems with 0.3-0.4 millions of unknowns on our Dell Precision 690 workstation using one core.
Nuclear photonics at ultra-high counting rates and higher multipole excitations
Energy Technology Data Exchange (ETDEWEB)
Thirolf, P. G.; Habs, D.; Filipescu, D.; Gernhaeuser, R.; Guenther, M. M.; Jentschel, M.; Marginean, N.; Pietralla, N. [Fakultaet f. Physik, Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany); Fakultaet f. Physik, Ludwig-Maximilians-Universitaet Muenchen, Garching, Germany and Max-Planck-Institute f. Quantum Optics, Garching (Germany); IFIN-HH, Bucharest-Magurele (Romania); Physik Department E12,Technische Universitaet Muenchen, Garching (Germany); Max-Planck-Institute f. Quantum Optics, Garching (Germany); Institut Laue-Langevin, Grenoble (France); Physik Department E12,Technische Universitaet Muenchen, Garching (Germany); Institut f. Kernphysik, Technische Universitaet Darmstadt (Germany)
2012-07-09
Next-generation {gamma} beams from laser Compton-backscattering facilities like ELI-NP (Bucharest)] or MEGa-Ray (Livermore) will drastically exceed the photon flux presently available at existing facilities, reaching or even exceeding 10{sup 13}{gamma}/sec. The beam structure as presently foreseen for MEGa-Ray and ELI-NP builds upon a structure of macro-pulses ({approx}120 Hz) for the electron beam, accelerated with X-band technology at 11.5 GHz, resulting in a micro structure of 87 ps distance between the electron pulses acting as mirrors for a counterpropagating intense laser. In total each 8.3 ms a {gamma} pulse series with a duration of about 100 ns will impinge on the target, resulting in an instantaneous photon flux of about 10{sup 18}{gamma}/s, thus introducing major challenges in view of pile-up. Novel {gamma} optics will be applied to monochromatize the {gamma} beam to ultimately {Delta}E/E{approx}10{sup -6}. Thus level-selective spectroscopy of higher multipole excitations will become accessible with good contrast for the first time. Fast responding {gamma} detectors, e.g. based on advanced scintillator technology (e.g. LaBr{sub 3}(Ce)) allow for measurements with count rates as high as 10{sup 6}-10{sup 7}{gamma}/s without significant drop of performance. Data handling adapted to the beam conditions could be performed by fast digitizing electronics, able to sample data traces during the micro-pulse duration, while the subsequent macro-pulse gap of ca. 8 ms leaves ample time for data readout. A ball of LaBr{sub 3} detectors with digital readout appears to best suited for this novel type of nuclear photonics at ultra-high counting rates.
Ibeid, Huda
2016-03-04
Exascale systems are predicted to have approximately 1 billion cores, assuming gigahertz cores. Limitations on affordable network topologies for distributed memory systems of such massive scale bring new challenges to the currently dominant parallel programing model. Currently, there are many efforts to evaluate the hardware and software bottlenecks of exascale designs. It is therefore of interest to model application performance and to understand what changes need to be made to ensure extrapolated scalability. The fast multipole method (FMM) was originally developed for accelerating N-body problems in astrophysics and molecular dynamics but has recently been extended to a wider range of problems. Its high arithmetic intensity combined with its linear complexity and asynchronous communication patterns make it a promising algorithm for exascale systems. In this paper, we discuss the challenges for FMM on current parallel computers and future exascale architectures, with a focus on internode communication. We focus on the communication part only; the efficiency of the computational kernels are beyond the scope of the present study. We develop a performance model that considers the communication patterns of the FMM and observe a good match between our model and the actual communication time on four high-performance computing (HPC) systems, when latency, bandwidth, network topology, and multicore penalties are all taken into account. To our knowledge, this is the first formal characterization of internode communication in FMM that validates the model against actual measurements of communication time. The ultimate communication model is predictive in an absolute sense; however, on complex systems, this objective is often out of reach or of a difficulty out of proportion to its benefit when there exists a simpler model that is inexpensive and sufficient to guide coding decisions leading to improved scaling. The current model provides such guidance.
Wilson, David B.
1981-01-01
Surveys the research of scientists like Joule, Kelvin, Maxwell, Clausius, and Boltzmann as it comments on the basic conceptual issues involved in the development of a more precise kinetic theory and the idea of a kinetic atom. (Author/SK)
Cumulative stress and autonomic dysregulation in a community sample.
Lampert, Rachel; Tuit, Keri; Hong, Kwang-Ik; Donovan, Theresa; Lee, Forrester; Sinha, Rajita
2016-05-01
Whether cumulative stress, including both chronic stress and adverse life events, is associated with decreased heart rate variability (HRV), a non-invasive measure of autonomic status which predicts poor cardiovascular outcomes, is unknown. Healthy community dwelling volunteers (N = 157, mean age 29 years) participated in the Cumulative Stress/Adversity Interview (CAI), a 140-item event interview measuring cumulative adversity including major life events, life trauma, recent life events and chronic stressors, and underwent 24-h ambulatory ECG monitoring. HRV was analyzed in the frequency domain and standard deviation of NN intervals (SDNN) calculated. Initial simple regression analyses revealed that total cumulative stress score, chronic stressors and cumulative adverse life events (CALE) were all inversely associated with ultra low-frequency (ULF), very low-frequency (VLF) and low-frequency (LF) power and SDNN (all p stress and chronic stress each was significantly associated with SDNN and ULF even after the highly significant contributions of age and sex, with no other covariates accounting for additional appreciable variance. For VLF and LF, both total cumulative stress and chronic stress significantly contributed to the variance alone but were not longer significant after adjusting for race and health behaviors. In summary, total cumulative stress, and its components of adverse life events and chronic stress were associated with decreased cardiac autonomic function as measured by HRV. Findings suggest one potential mechanism by which stress may exert adverse effects on mortality in healthy individuals. Primary preventive strategies including stress management may prove beneficial.
Energy Technology Data Exchange (ETDEWEB)
McCone, John A.
1960-01-31
The first twenty five semiannual reports of the United States Atomic Energy Commission to Congress cover the major unclassified activities of the Commission from January 1947 through January 1959. In addition to the semiannual summaries, a series of special reports on important atomic energy programs were included in many of the semiannual reports. This cumulative name and subject index provides a guide to the information published in these reports. Beginning in 1960, the Commission will be issuing annual reports, each separately indexed, ceasing the semiannual reporting.
Entanglement entropy and particle number cumulants of disordered fermions
Burmistrov, I. S.; Tikhonov, K. S.; Gornyi, I. V.; Mirlin, A. D.
2017-08-01
We study the entanglement entropy and particle number cumulants for a system of disordered noninteracting fermions in d dimensions. We show, both analytically and numerically, that for a weak disorder the entanglement entropy and the second cumulant (particle number variance) are proportional to each other with a universal coefficient. The corresponding expressions are analogous to those in the clean case but with a logarithmic factor regularized by the mean free path rather than by the system size. We also determine the scaling of higher cumulants by analytical (weak disorder) and numerical means. Finally, we predict that the particle number variance and the entanglement entropy are nonanalytic functions of disorder at the Anderson transition.
Bajaj, Chandrajit; Chen, Shun-Chuan; Rand, Alexander
2011-01-01
In order to compute polarization energy of biomolecules, we describe a boundary element approach to solving the linearized Poisson-Boltzmann equation. Our approach combines several important features including the derivative boundary formulation of the problem and a smooth approximation of the molecular surface based on the algebraic spline molecular surface. State of the art software for numerical linear algebra and the kernel independent fast multipole method is used for both simplicity and efficiency of our implementation. We perform a variety of computational experiments, testing our method on a number of actual proteins involved in molecular docking and demonstrating the effectiveness of our solver for computing molecular polarization energy. PMID:21660123
The polarization observables T, P, and H and their impact on $\\gamma p \\to p\\pi^0$ multipoles
Hartmann, J; Anisovich, A V; Bayadilov, D; Beck, R; Becker, M; Beloglazov, Y; Berlin, A; Bichow, M; Böse, S; Brinkmann, K -Th; Crede, V; Dieterle, M; Eberhardt, H; Elsner, D; Fornet-Ponse, K; Friedrich, St; Frommberger, F; Funke, Ch; Gottschall, M; Gridnev, A; Grüner, M; Görtz, St; Gutz, E; Hammann, Ch; Hannappel, J; Hannen, V; Herick, J; Hillert, W; Hoffmeister, Ph; Honisch, Ch; Jahn, O; Jude, T; Käser, A; Kaiser, D; Kalinowsky, H; Kalischewski, F; Klassen, P; Keshelashvili, I; Klein, F; Klempt, E; Koop, K; Krusche, B; Kube, M; Lang, M; Lopatin, I; Makonyi, K; Messi, F; Metag, V; Meyer, W; Müller, J; Nanova, M; Nikonov, V; Novinski, D; Novotny, R; Piontek, D; Reeve, S; Rosenbaum, Ch; Roth, B; Reicherz, G; Rostomyan, T; Runkel, St; Sarantsev, A; Schmidt, Ch; Schmieden, H; Schmitz, R; Seifen, T; Sokhoyan, V; Thämer, Ph; Thiel, A; Thoma, U; Urban, M; van Pee, H; Walther, D; Wendel, Ch; Wiedner, U; Wilson, A; Winnebeck, A; Witthauer, L
2015-01-01
Data on the polarization observables T, P, and H for the reaction $\\gamma p\\to p\\pi^0$ are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction.
The polarization observables T, P, and H and their impact on γp→pπ0 multipoles
Directory of Open Access Journals (Sweden)
J. Hartmann
2015-09-01
Full Text Available Data on the polarization observables T, P, and H for the reaction γp→pπ0 are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction.
Institute of Scientific and Technical Information of China (English)
Ting Lei; Zhenhan Yao; Haitao Wang; Pengbo Wang
2006-01-01
In this paper, an adaptive boundary element method (BEM) is presented for solving 3-D elasticity problems. The numerical scheme is accelerated by the new version of fast multipole method (FMM) and parallelized on distributed memory architectures. The resulting solver is applied to the study of representative volume element (RVE)for short fiberreinforced composites with complex inclusion geometry. Numerical examples performed on a 32-processor cluster show that the proposed method is both accurate and efficient. And can solve problems of large size that are challenging to existing state-of-the-art domain methods.
Stöhlker, T; Ma, X; Ludziejewski, T; Beyer, H F; Bosch, F; Brinzanescu, O; Dunford, R W; Eichler, J; Hagmann, S; Ichihara, A; Kozhuharov, C; Krämer, A; Liesen, D; Mokler, P H; Stachura, Z; Swiat, P; Warczak, A
2001-02-05
Radiative electron capture, the time-reversed photoionization process occurring in ion-atom collisions, provides presently the only access to photoionization studies for very highly charged ions. By applying the deceleration mode of the ESR storage ring, we studied this process in low-energy collisions of bare uranium ions with low- Z target atoms. This technique allows us to extend the current information about photoionization to much lower energies than those accessible for neutral heavy elements in the direct reaction channel. The results prove that for high- Z systems, higher-order multipole contributions and magnetic corrections persist even at energies close to the threshold.
Misquitta, Alston J; Stone, Anthony J
2016-09-13
Creating accurate, analytic atom-atom potentials for small organic molecules from first principles can be a time-consuming and computationally intensive task, particularly if we also require them to include explicit polarization terms, which are essential in many systems. We describe how the CamCASP suite of programs can be used to generate such potentials using some of the most accurate electronic structure methods currently applicable. We derive the long-range terms from monomer properties and determine the short-range anisotropy parameters by a novel and robust method based on the iterated stockholder atom approach. Using these techniques, we develop distributed multipole models for the electrostatic, polarization, and dispersion interactions in the pyridine dimer and develop a series of many-body potentials for the pyridine system. Even the simplest of these potentials exhibits root mean square errors of only about 0.6 kJ mol(-1) for the low-energy pyridine dimers, significantly surpassing the best empirical potentials. Our best model is shown to support eight stable minima, four of which have not been reported before in the literature. Further, the functional form can be made systematically more elaborate so as to improve the accuracy without a significant increase in the human-time spent in their generation. We investigate the effects of anisotropy, rank of multipoles, and choice of polarizability and dispersion models.
Hettema, Hinne; Wormer, Paul E. S.; Thakkar, Ajit J.
Ab initio many body perturbation theory is used to calculate the imaginary frequency multipole polarizabilities of N2, Cl2, CO, HCl and HBr as a function of bond length. These are combined with previously calculated dynamic polarizabilities for rare gas atoms to obtain the intramolecular bond length dependence of the anisotropic dispersion and induction coefficients through R-8 for AB-X (AB = N2, Cl2, CO, HCl, HBr and X = He, Ne, Ar, Kr, Xe) interactions.
Online Scheduling in Manufacturing A Cumulative Delay Approach
Suwa, Haruhiko
2013-01-01
Online scheduling is recognized as the crucial decision-making process of production control at a phase of “being in production" according to the released shop floor schedule. Online scheduling can be also considered as one of key enablers to realize prompt capable-to-promise as well as available-to-promise to customers along with reducing production lead times under recent globalized competitive markets. Online Scheduling in Manufacturing introduces new approaches to online scheduling based on a concept of cumulative delay. The cumulative delay is regarded as consolidated information of uncertainties under a dynamic environment in manufacturing and can be collected constantly without much effort at any points in time during a schedule execution. In this approach, the cumulative delay of the schedule has the important role of a criterion for making a decision whether or not a schedule revision is carried out. The cumulative delay approach to trigger schedule revisions has the following capabilities for the ...
Cumulative Risks of Foster Care Placement for Danish Children
DEFF Research Database (Denmark)
Fallesen, Peter; Emanuel, Natalia; Wildeman, Christopher
2014-01-01
Although recent research suggests that the cumulative risk of foster care placement is far higher for American children than originally suspected, little is known about the cumulative risk of foster care placement in other countries, which makes it difficult to gauge the degree to which factor...... is for Danish children. Results suggest that at the beginning of the study period (in 1998) the cumulative risk of foster care placement for Danish children was roughly in line with the risk for American children. Yet, by the end of the study period (2010), the risk had declined to half the risk for American...... foster care placement is salient in other contexts. In this article, we provide companion estimates to those provided in recent work on the US by using Danish registry data and synthetic cohort life tables to show how high and unequally distributed the cumulative risk of foster care placement...
Mapping cumulative human impacts in the eastern North Sea
DEFF Research Database (Denmark)
Stock, A.; Andersen, Jesper; Heinänen, S.
of the MSFD; and 3) to deepen the understanding of how errors in expert judgment affect the resulting cumulative human impact maps by means of Monte Carlo simulations. We combined existing data sets on the spatial distribution of 33 anthropogenic stressors (linked to the MSFD pressures) and 28 key habitats....... In contrast, the predicted impacts for much of the Norwegian EEZ and areas far offshore were lower. The Monte Carlo simulations confirmed earlier findings that mapping cumulative impacts is generally "robust", but also showed that specific combinations of errors can seriously change local and regional...... on marine ecosystems have only recently been developed. The aims of our study were: 1) to develop a map of cumulative human impacts for the Danish, Swedish, Norwegian and German parts of the Greater North Sea; 2) to adjust the existing methods for mapping cumulative human impacts to fit the requirements...
Cumulative Production Per Township - SaMiRa
U.S. Geological Survey, Department of the Interior — This dataset contains a selected township grid within the Sagebrush Mineral Resource Assessment project (SaMiRa) study area attributed with cumulative oil and gas...
Cumulative radiation exposure in children with cystic fibrosis.
LENUS (Irish Health Repository)
O'Reilly, R
2010-02-01
This retrospective study calculated the cumulative radiation dose for children with cystic fibrosis (CF) attending a tertiary CF centre. Information on 77 children with a mean age of 9.5 years, a follow up time of 658 person years and 1757 studies including 1485 chest radiographs, 215 abdominal radiographs and 57 computed tomography (CT) scans, of which 51 were thoracic CT scans, were analysed. The average cumulative radiation dose was 6.2 (0.04-25) mSv per CF patient. Cumulative radiation dose increased with increasing age and number of CT scans and was greater in children who presented with meconium ileus. No correlation was identified between cumulative radiation dose and either lung function or patient microbiology cultures. Radiation carries a risk of malignancy and children are particularly susceptible. Every effort must be made to avoid unnecessary radiation exposure in these patients whose life expectancy is increasing.
Macroscopic cumulative fatigue damage of material under nonsymmetrical cycle
Institute of Scientific and Technical Information of China (English)
盖秉政
2002-01-01
Hashin's macroscopic theory of fatigue damage is further discussed and a new method has been proposed for prediction of cumulative fatigue damage of material and its lifetime under nonsymmetrical cyclic loading.
Translation-Invariant Representation for Cumulative Foot Pressure Images
Zheng, Shuai; Tan, Tieniu
2010-01-01
Human can be distinguished by different limb movements and unique ground reaction force. Cumulative foot pressure image is a 2-D cumulative ground reaction force during one gait cycle. Although it contains pressure spatial distribution information and pressure temporal distribution information, it suffers from several problems including different shoes and noise, when putting it into practice as a new biometric for pedestrian identification. In this paper, we propose a hierarchical translation-invariant representation for cumulative foot pressure images, inspired by the success of Convolutional deep belief network for digital classification. Key contribution in our approach is discriminative hierarchical sparse coding scheme which helps to learn useful discriminative high-level visual features. Based on the feature representation of cumulative foot pressure images, we develop a pedestrian recognition system which is invariant to three different shoes and slight local shape change. Experiments are conducted on...
Saßmannshausen, Heiner; Deiglmayr, Johannes; Merkt, Frédéric
2016-12-01
We present an overview of our recent investigations of long-range interactions in an ultracold Cs Rydberg gas. These interactions are studied by high-resolution photoassociation spectroscopy, using excitation close to one-photon transitions into np3/2 Rydberg states with pulsed and continuous-wave ultraviolet laser radiation, and lead to the formation of long-range Cs2 molecules. We observe two types of molecular resonances. The first type originates from the correlated excitation of two atoms into Rydberg-atom-pair states interacting at long range via multipole-multipole interactions. The second type results from the interaction of one atom excited to a Rydberg state with one atom in the electronic ground state. Which type of resonances is observed in the experiments depends on the laser intensity and frequency and on the pulse sequences used to prepare the Rydberg states. We obtain insights into both types of molecular resonances by modelling the interaction potentials, using a multipole expansion of the long-range interaction for the first type of resonances and a Fermi-contact pseudo-potential for the second type of resonances. We analyse the relation of these long-range molecular resonances to molecular Rydberg states and ion-pair states, and discuss their decay channels into atomic and molecular ions. In experiments carried out with a two-colour two-photon excitation scheme, we observe a large enhancement of Rydberg-excitation probability, which we interpret as a saturable autocatalytic antiblockade phenomenon.
Some Characterization Results on Dynamic Cumulative Residual Tsallis Entropy
Directory of Open Access Journals (Sweden)
Madan Mohan Sati
2015-01-01
Full Text Available We propose a generalized cumulative residual information measure based on Tsallis entropy and its dynamic version. We study the characterizations of the proposed information measure and define new classes of life distributions based on this measure. Some applications are provided in relation to weighted and equilibrium probability models. Finally the empirical cumulative Tsallis entropy is proposed to estimate the new information measure.
Steps and pips in the history of the cumulative recorder.
Lattal, Kennon A.
2004-01-01
From its inception in the 1930s until very recent times, the cumulative recorder was the most widely used measurement instrument in the experimental analysis of behavior. It was an essential instrument in the discovery and analysis of schedules of reinforcement, providing the first real-time analysis of operant response rates and patterns. This review traces the evolution of the cumulative recorder from Skinner's early modified kymographs through various models developed by Skinner and his co...
Childhood Cumulative Risk Exposure and Adult Amygdala Volume and Function.
Evans, Gary W; Swain, James E; King, Anthony P; Wang, Xin; Javanbakht, Arash; Ho, S Shaun; Angstadt, Michael; Phan, K Luan; Xie, Hong; Liberzon, Israel
2016-06-01
Considerable work indicates that early cumulative risk exposure is aversive to human development, but very little research has examined the neurological underpinnings of these robust findings. This study investigates amygdala volume and reactivity to facial stimuli among adults (mean 23.7 years of age, n = 54) as a function of cumulative risk exposure during childhood (9 and 13 years of age). In addition, we test to determine whether expected cumulative risk elevations in amygdala volume would mediate functional reactivity of the amygdala during socioemotional processing. Risks included substandard housing quality, noise, crowding, family turmoil, child separation from family, and violence. Total and left hemisphere adult amygdala volumes were positively related to cumulative risk exposure during childhood. The links between childhood cumulative risk exposure and elevated amygdala responses to emotionally neutral facial stimuli in adulthood were mediated by the corresponding amygdala volumes. Cumulative risk exposure in later adolescence (17 years of age), however, was unrelated to subsequent adult amygdala volume or function. Physical and socioemotional risk exposures early in life appear to alter amygdala development, rendering adults more reactive to ambiguous stimuli such as neutral faces. These stress-related differences in childhood amygdala development might contribute to the well-documented psychological distress as a function of early risk exposure.
Loring, FH
2014-01-01
Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec
Charge Changing Experiments and Multipole Expansions of Electron Loss to the Continuum.
Atan, H.
Available from UMI in association with The British Library. Charge changing processes involving single electron loss for 0.6-2.2 MeV _sp{2}{4 }He^{+} ions and 2.0-3.0 MeV _sp{2}{3 }He^{+} ions, and single electron capture for 0.6-2.2 MeV _sp {2}{4}He^{+ } ions colliding with He, Ne and Ar have bee studied. The gas target was in the form of a gas beam jet, well localised and directed, obtained using a multicapillary array system. The measured absolute cross sections for single electron loss sigma_{12 }, were in good agreement with most other experimental data. These results were also compared with the theoretical quantal, semi-classical and classical calculations. For a He target, quantal Born approximation calculations gave good agreement especially towards the high energy region but not for an Ar target. The semi-classical calculations gave good agreement for all three target systems, in terms of the magnitude, velocity dependence as well the Z _{t}, dependence. The classical calculations gave not only a good estimate of the cross -sections but also predicted the velocity dependence quite accurately. The measured absolute cross sections for single electron capture sigma_{10} agreed well with most other experimental data and with the classical binary encounter calculations. Electron loss to the continuum (ELC) for 1.4-2.8 MeV He^{+} colliding with He, Ne and Ar have also been studied using a second-order focussing, 30^circ parallel plate spectrometer. The analysis was performed using a specially developed multipole expansion method, allowing an extraction of the parameters in an apparatus independent manner. The first order anisotropy parameter beta_1, was found to exhibit a systematic target dependence, with negative values for Ne and Ar targets, indicating an asymmetric cusp with an enhanced intensity of electrons at velocities lower than that of the ions. Such cusp shape was not predicted by any existing first-order theory. The second-order anisotropy parameter
Real-time digital signal recovery for a multi-pole low-pass transfer function system
Lee, Jhinhwan
2017-08-01
In order to solve the problems of waveform distortion and signal delay by many physical and electrical systems with multi-pole linear low-pass transfer characteristics, a simple digital-signal-processing (DSP)-based method of real-time recovery of the original source waveform from the distorted output waveform is proposed. A mathematical analysis on the convolution kernel representation of the single-pole low-pass transfer function shows that the original source waveform can be accurately recovered in real time using a particular moving average algorithm applied on the input stream of the distorted waveform, which can also significantly reduce the overall delay time constant. This method is generalized for multi-pole low-pass systems and has noise characteristics of the inverse of the low-pass filter characteristics. This method can be applied to most sensors and amplifiers operating close to their frequency response limits to improve the overall performance of data acquisition systems and digital feedback control systems.
Multipole analysis of IceCube data to search for dark matter accumulated in the Galactic halo
Energy Technology Data Exchange (ETDEWEB)
Aartsen, M.G.; Hill, G.C.; Robertson, S.; Whelan, B.J. [University of Adelaide, School of Chemistry and Physics, Adelaide, SA (Australia); Ackermann, M.; Berghaus, P.; Bernardini, E.; Bretz, H.P.; Cruz Silva, A.H.; Gluesenkamp, T.; Gora, D.; Jacobi, E.; Kaminsky, B.; Karg, T.; Middell, E.; Mohrmann, L.; Nahnhauer, R.; Schoenwald, A.; Shanidze, R.; Spiering, C.; Stoessl, A.; Terliuk, A.; Yanez, J.P. [DESY, Zeuthen (Germany); Adams, J.; Brown, A.M.; Hickford, S.; Macias, O. [University of Canterbury, Department of Physics and Astronomy, Christchurch (New Zealand); Aguilar, J.A.; Altmann, D.; Christov, A.; Montaruli, T.; Rameez, M.; Vallecorsa, S. [Universite de Geneve, Departement de physique nucleaire et corpusculaire, Geneva (Switzerland); Ahlers, M.; Arguelles, C.; BenZvi, S.; Chirkin, D.; Day, M.; Desiati, P.; Diaz-Velez, J.C.; Eisch, J.; Fadiran, O.; Feintzeig, J.; Gladstone, L.; Halzen, F.; Hoshina, K.; Jacobsen, J.; Jero, K.; Karle, A.; Kauer, M.; Kelley, J.L.; Kheirandish, A.; Kopper, C.; Kurahashi, N.; Larsen, D.T.; Maruyama, R.; McNally, F.; Middlemas, E.; Morse, R.; Rees, I.; Riedel, B.; Rodrigues, J.P.; Santander, M.; Tobin, M.N.; Tosi, D.; Vandenbroucke, J.; Van Santen, J.; Weaver, C.; Wellons, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N. [University of Wisconsin, Department of Physics, Wisconsin IceCube Particle Astrophysics Center, Madison, WI (United States); Ahrens, M.; Bohm, C.; Danninger, M.; Finley, C.; Flis, S.; Hulth, P.O.; Hultqvist, K.; Walck, C.; Wolf, M.; Zoll, M. [Stockholm University, Department of Physics, Oskar Klein Centre, Stockholm (Sweden); Anderson, T.; Arlen, T.C.; De Andre, J.P.A.M.; DeYoung, T.; Dunkman, M.; Eagan, R.; Groh, J.C.; Huang, F.; Quinnan, M.; Smith, M.W.E.; Stanisha, N.A.; Tesic, G. [Pennsylvania State University, Department of Physics, University Park, PA (United States); Auffenberg, J.; Bissok, M.; Blumenthal, J.; Gier, D.; Gretskov, P.; Haack, C.; Hallen, P.; Heinen, D.; Hellwig, D.; Jagielski, K.; Koob, A.; Kriesten, A.; Krings, K.; Leuermann, M.; Paul, L.; Penek, Oe.; Puetz, J.; Raedel, L.; Reimann, R.; Rongen, M.; Schoenen, S.; Schukraft, A.; Vehring, M.; Wallraff, M.; Wichary, C.; Wiebusch, C.H.; Zierke, S. [RWTH Aachen University, III. Physikalisches Institut, Aachen (Germany); Bai, X. [South Dakota School of Mines and Technology, Physics Department, Rapid City, SD (United States); Barwick, S.W.; Yodh, G. [University of California, Department of Physics and Astronomy, Irvine, CA (United States); Baum, V.; Eberhardt, B.; Koepke, L.; Kroll, G.; Luenemann, J.; Sander, H.G.; Schatto, K.; Wiebe, K. [University of Mainz, Institute of Physics, Mainz (Germany); Beatty, J.J. [Ohio State University, Department of Physics, Center for Cosmology and Astro-Particle Physics, Columbus, OH (United States); Ohio State University, Department of Astronomy, Columbus, OH (United States); Becker Tjus, J.; Bos, F.; Eichmann, B.; Fedynitch, A.; Kroll, M.; Saba, S.M.; Schoeneberg, S.; Unger, E. [Ruhr-Universitaet Bochum, Fakultaet fuer Physik und Astronomie, Bochum (Germany); Becker, K.H.; Bindig, D.; Fischer-Wasels, T.; Helbing, K.; Hoffmann, R.; Klaes, J.; Kopper, S.; Naumann, U.; Obertacke, A.; Omairat, A.; Posselt, J.; Soldin, D.; Tepe, A. [University of Wuppertal, Department of Physics, Wuppertal (Germany); Berley, D.; Blaufuss, E.; Christy, B.; Felde, J.; Goodman, J.A.; Hellauer, R.; Hoffman, K.D.; Huelsnitz, W.; Meagher, K.; Olivas, A.; Redl, P.; Richman, M.; Schmidt, T.; Sullivan, G.W.; Wissing, H. [University of Maryland, Department of Physics, College Park, MD (United States); Bernhard, A.; Coenders, S.; Gross, A.; Jurkovic, M.; Leute, J.; Resconi, E.; Schulz, O.; Sestayo, Y. [Technische Universitaet Muenchen, Garching (Germany); Besson, D.Z. [University of Kansas, Department of Physics and Astronomy, Lawrence, KS (United States); Binder, G.; Gerhardt, L.; Ha, C.; Klein, S.R.; Miarecki, S. [University of California, Department of Physics, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Boersma, D.J.; Botner, O.; Euler, S.; Hallgren, A.; Perez de los Heros, C.; Stroem, R.; Taavola, H. [Uppsala University, Department of Physics and Astronomy, Uppsala (Sweden); Bose, D.; Rott, C. [Sungkyunkwan University, Department of Physics, Suwon (Korea, Republic of); Collaboration: IceCube Collaboration; and others
2015-01-01
Dark matter which is bound in the Galactic halo might self-annihilate and produce a flux of stable final state particles, e.g. high energy neutrinos. These neutrinos can be detected with IceCube, a cubic-kilometer sized Cherenkov detector. Given IceCube's large field of view, a characteristic anisotropy of the additional neutrino flux is expected. In this paper we describe a multipole method to search for such a large-scale anisotropy in IceCube data. This method uses the expansion coefficients of a multipole expansion of neutrino arrival directions and incorporates signal-specific weights for each expansion coefficient. We apply the technique to a high-purity muon neutrino sample from the Northern Hemisphere. The final result is compatible with the nullhypothesis. As no signal was observed, we present limits on the self-annihilation cross-section averaged over the relative velocity distribution left angle σ{sub A}υ right angle down to 1.9 x 10{sup -23} cm{sup 3} s{sup -1} for a dark matter particle mass of 700-1,000 GeV and direct annihilation into ν anti ν. The resulting exclusion limits come close to exclusion limits from γ-ray experiments, that focus on the outer Galactic halo, for high dark matter masses of a few TeV and hard annihilation channels. (orig.)
Multipole analysis of IceCube data to search for dark matter accumulated in the Galactic halo
Aartsen, M G; Adams, J; Aguilar, J A; Ahlers, M; Ahrens, M; Altmann, D; Anderson, T; Arguelles, C; Arlen, T C; Auffenberg, J; Bai, X; Barwick, S W; Baum, V; Beatty, J J; Tjus, J Becker; Becker, K -H; BenZvi, S; Berghaus, P; Berley, D; Bernardini, E; Bernhard, A; Besson, D Z; Binder, G; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bos, F; Bose, D; Böser, S; Botner, O; Brayeur, L; Bretz, H -P; Brown, A M; Casey, J; Casier, M; Chirkin, D; Christov, A; Christy, B; Clark, K; Classen, L; Clevermann, F; Coenders, S; Cowen, D F; Silva, A H Cruz; Danninger, M; Daughhetee, J; Davis, J C; Day, M; de André, J P A M; De Clercq, C; De Ridder, S; Desiati, P; de Vries, K D; de With, M; DeYoung, T; Díaz-Vélez, J C; Dunkman, M; Eagan, R; Eberhardt, B; Eichmann, B; Eisch, J; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Felde, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Frantzen, K; Fuchs, T; Gaisser, T K; Gallagher, J; Gerhardt, L; Gier, D; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Golup, G; Gonzalez, J G; Goodman, J A; Góra, D; Grandmont, D T; Grant, D; Gretskov, P; Groh, J C; Groß, A; Ha, C; Haack, C; Ismail, A Haj; Hallen, P; Hallgren, A; Halzen, F; Hanson, K; Hebecker, D; Heereman, D; Heinen, D; Helbing, K; Hellauer, R; Hellwig, D; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, R; Homeier, A; Hoshina, K; Huang, F; Huelsnitz, W; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Jagielski, K; Japaridze, G S; Jero, K; Jlelati, O; Jurkovic, M; Kaminsky, B; Kappes, A; Karg, T; Karle, A; Kauer, M; Kelley, J L; Kheirandish, A; Kiryluk, J; Kläs, J; Klein, S R; Köhne, J -H; Kohnen, G; Kolanoski, H; Koob, A; Köpke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Kriesten, A; Krings, K; Kroll, G; Kroll, M; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Larsen, D T; Larson, M J; Lesiak-Bzdak, M; Leuermann, M; Leute, J; Lünemann, J; Macías, O; Madsen, J; Maggi, G; Maruyama, R; Mase, K; Matis, H S; McNally, F; Meagher, K; Medici, M; Meli, A; Meures, T; Miarecki, S; Middell, E; Middlemas, E; Milke, N; Miller, J; Mohrmann, L; Montaruli, T; Morse, R; Nahnhauer, R; Naumann, U; Niederhausen, H; Nowicki, S C; Nygren, D R; Obertacke, A; Odrowski, S; Olivas, A; Omairat, A; O'Murchadha, A; Palczewski, T; Paul, L; Penek, Ö; Pepper, J A; Heros, C Pérez de los; Pfendner, C; Pieloth, D; Pinat, E; Posselt, J; Price, P B; Przybylski, G T; Pütz, J; Quinnan, M; Rädel, L; Rameez, M; Rawlins, K; Redl, P; Rees, I; Reimann, R; Resconi, E; Rhode, W; Richman, M; Riedel, B; Robertson, S; Rodrigues, J P; Rongen, M; Rott, C; Ruhe, T; Ruzybayev, B; Ryckbosch, D; Saba, S M; Sander, H -G; Sandroos, J; Santander, M; Sarkar, S; Schatto, K; Scheriau, F; Schmidt, T; Schmitz, M; Schoenen, S; Schöneberg, S; Schönwald, A; Schukraft, A; Schulte, L; Schulz, O; Seckel, D; Sestayo, Y; Seunarine, S; Shanidze, R; Sheremata, C; Smith, M W E; Soldin, D; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stanisha, N A; Stasik, A; Stezelberger, T; Stokstad, R G; Stößl, A; Strahler, E A; Ström, R; Strotjohann, N L; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Tepe, A; Ter-Antonyan, S; Terliuk, A; Tešić, G; Tilav, S; Toale, P A; Tobin, M N; Tosi, D; Tselengidou, M; Unger, E; Usner, M; Vallecorsa, S; van Eijndhoven, N; Vandenbroucke, J; van Santen, J; Vehring, M; Voge, M; Vraeghe, M; Walck, C; Wallraff, M; Weaver, Ch; Wellons, M; Wendt, C; Westerhoff, S; Whelan, B J; Whitehorn, N; Wichary, C; Wiebe, K; Wiebusch, C H; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Ziemann, J; Zierke, S; Zoll, M
2014-01-01
Dark matter which is bound in the Galactic halo might self-annihilate and produce a flux of stable final state particles, e.g. high energy neutrinos. These neutrinos can be detected with IceCube, a cubic-kilometer sized Cherenkov detector. Given IceCube's large field of view, a characteristic anisotropy of the additional neutrino flux is expected. In this paper we describe a multipole method to search for such a large-scale anisotropy in IceCube data. This method uses the expansion coefficients of a multipole expansion of neutrino arrival directions and incorporates signal-specific weights for each expansion coefficient. We apply the technique to a high-purity muon neutrino sample from the Northern Hemisphere. The final result is compatible with the null-hypothesis. As no signal was observed, we present limits on the self-annihilation cross-section averaged over the relative velocity distribution $\\langle\\sigma v\\rangle$ down to $1.9\\cdot 10^{-23}\\,\\mathrm{cm}^3\\mathrm{s}^{-1}$ for a dark matter particle mass...
Wang, Han; Nakamura, Haruki; Fukuda, Ikuo
2016-03-21
We performed extensive and strict tests for the reliability of the zero-multipole (summation) method (ZMM), which is a method for estimating the electrostatic interactions among charged particles in a classical physical system, by investigating a set of various physical quantities. This set covers a broad range of water properties, including the thermodynamic properties (pressure, excess chemical potential, constant volume/pressure heat capacity, isothermal compressibility, and thermal expansion coefficient), dielectric properties (dielectric constant and Kirkwood-G factor), dynamical properties (diffusion constant and viscosity), and the structural property (radial distribution function). We selected a bulk water system, the most important solvent, and applied the widely used TIP3P model to this test. In result, the ZMM works well for almost all cases, compared with the smooth particle mesh Ewald (SPME) method that was carefully optimized. In particular, at cut-off radius of 1.2 nm, the recommended choices of ZMM parameters for the TIP3P system are α ≤ 1 nm(-1) for the splitting parameter and l = 2 or l = 3 for the order of the multipole moment. We discussed the origin of the deviations of the ZMM and found that they are intimately related to the deviations of the equilibrated densities between the ZMM and SPME, while the magnitude of the density deviations is very small.
Directory of Open Access Journals (Sweden)
Junqiang Lou
2017-03-01
Full Text Available This paper presents experimental identification and vibration suppression of a flexible manipulator with piezoelectric actuators and strain sensors using optimal multi-poles placement control. To precisely identify the system model, a reduced order transfer function with relocated zeros is proposed, and a first-order inertia element is added to the model. Comparisons show the identified model match closely with the experimental results both in the time and frequency domains, and a fit of 97.2% is achieved. Based on the identified model, a full-state multi-poles placement controller is designed, and the optimal locations of the closed loop poles are determined where the move distance of the closed loop poles is the shortest. The feasibility of the proposed controller is validated by simulations. Moreover, the controller is tested for different locations of the closed loop poles, and an excellent performance of the optimal locations of the closed loop poles is shown. Finally, the effectiveness of the proposed controller is demonstrated by experiments. Results show that the vibrations of the expected modes are significantly diminished. Accordingly, multi-mode vibrations of the manipulator are well attenuated.
Wang, Han; Nakamura, Haruki; Fukuda, Ikuo
2016-03-01
We performed extensive and strict tests for the reliability of the zero-multipole (summation) method (ZMM), which is a method for estimating the electrostatic interactions among charged particles in a classical physical system, by investigating a set of various physical quantities. This set covers a broad range of water properties, including the thermodynamic properties (pressure, excess chemical potential, constant volume/pressure heat capacity, isothermal compressibility, and thermal expansion coefficient), dielectric properties (dielectric constant and Kirkwood-G factor), dynamical properties (diffusion constant and viscosity), and the structural property (radial distribution function). We selected a bulk water system, the most important solvent, and applied the widely used TIP3P model to this test. In result, the ZMM works well for almost all cases, compared with the smooth particle mesh Ewald (SPME) method that was carefully optimized. In particular, at cut-off radius of 1.2 nm, the recommended choices of ZMM parameters for the TIP3P system are α ≤ 1 nm-1 for the splitting parameter and l = 2 or l = 3 for the order of the multipole moment. We discussed the origin of the deviations of the ZMM and found that they are intimately related to the deviations of the equilibrated densities between the ZMM and SPME, while the magnitude of the density deviations is very small.
Bertinelli, F; Berthollon-Vitte, S; Glaude, D; Vanenkov, I
2006-01-01
The quality control implemented at all LHC dipole assemblers includes precise mechanical measurements of the geometry of collared coils. A cross-analysis performed between mechanical and magnetic measurements data shows a correlation between collared coils outer dimensions and the normal quadrupole multipole (b2) for one dipole assembler. The profile geometry of the single collars - as determined from 3D measurements at the collar suppliers and CERN - could not account alone for the significant left â right aperture asymmetry observed. This triggered a deeper investigation on different elements of the geometry of single collars. The results of this work show that the relative positioning of the collaring holes, allowing a small bending deformation of collars under the effect of coil pre-stress, is an important effect that generates a b2 multipole at the limit of specification. The study has deepened the understanding of the factors affecting collared coil geometry and field quality. The precision of 3D m...
Institute of Scientific and Technical Information of China (English)
LIU Yong; HAO Shuang-hui; HAO Ming-hui
2009-01-01
We developed a novel absolute multi-pole encoder structure to improve the resolution of the multi-pole encoder, realize absolute output and reduce the manufacturing cost of the encoder. The structure includes two ring alnicos defined as index track and sub-division track, respectively. The index track is magnetized based on the improved gray code, with linear halls placed around the track evenly. The outputs of linear halls show the region the rotor belongs to. The sub-division track is magnetized to N-S-N-S (north-south-north-south), and the number of N-S pole pairs is determined by the index track. Three linear hall sensors with an air-gap of 2 mm are used to translate the magnetic filed to voltage signals. The relative offset in a single N-S is obtained through look-up. The magnetic encoder is calibrated using a higher-resolution incremental optical encoder. The pulse output from the optical encoder and hall signals from the magnetic encoder are sampled at the same time and transmitted to a computer, and the relation between them is calculated, and stored in the FLASH of MCU (micro controller unit) for look-up. In the working state, the absolute angle is derived by looking-up with hall signals. The structure is simple and the manufacturing cost is very low and suitable for mass production.
An efficient blocking M2L translation for low-frequency fast multipole method in three dimensions
Takahashi, Toru; Shimba, Yuta; Isakari, Hiroshi; Matsumoto, Toshiro
2016-05-01
We propose an efficient scheme to perform the multipole-to-local (M2L) translation in the three-dimensional low-frequency fast multipole method (LFFMM). Our strategy is to combine a group of matrix-vector products associated with M2L translation into a matrix-matrix product in order to diminish the memory traffic. For this purpose, we first developed a grouping method (termed as internal blocking) based on the congruent transformations (rotational and reflectional symmetries) of M2L-translators for each target box in the FMM hierarchy (adaptive octree). Next, we considered another method of grouping (termed as external blocking) that was able to handle M2L translations for multiple target boxes collectively by using the translational invariance of the M2L translation. By combining these internal and external blockings, the M2L translation can be performed efficiently whilst preservingthe numerical accuracy exactly. We assessed the proposed blocking scheme numerically and applied it to the boundary integral equation method to solve electromagnetic scattering problems for perfectly electrical conductor. From the numerical results, it was found that the proposed M2L scheme achieved a few times speedup compared to the non-blocking scheme.
Cumulative risks of foster care placement for Danish children.
Fallesen, Peter; Emanuel, Natalia; Wildeman, Christopher
2014-01-01
Although recent research suggests that the cumulative risk of foster care placement is far higher for American children than originally suspected, little is known about the cumulative risk of foster care placement in other countries, which makes it difficult to gauge the degree to which factor foster care placement is salient in other contexts. In this article, we provide companion estimates to those provided in recent work on the US by using Danish registry data and synthetic cohort life tables to show how high and unequally distributed the cumulative risk of foster care placement is for Danish children. Results suggest that at the beginning of the study period (in 1998) the cumulative risk of foster care placement for Danish children was roughly in line with the risk for American children. Yet, by the end of the study period (2010), the risk had declined to half the risk for American children. Our results also show some variations by parental ethnicity and sex, but these differences are small. Indeed, they appear quite muted relative to racial/ethnic differences in these risks in the United States. Last, though cumulative risks are similar between Danish and American children (especially at the beginning of the study period), the age-specific risk profiles are markedly different, with higher risks for older Danish children than for older American children.
Latino Mothers' Cumulative Food Insecurity Exposure and Child Body Composition.
Hernandez, Daphne C
2016-01-01
To document whether an intergenerational transmission of food insecurity is occurring by assessing low-income foreign-born Latino mothers' experiences with food insecurity as none, once (either childhood or adulthood) or twice (during both childhood and adulthood). Also the association between maternal cumulative food insecurity and children's body composition was examined. Maternal self-reported surveys on retrospective measures of food insecurity during childhood, current measures of food insecurity, and demographics were collected from Houston-area community centers (N = 96). Children's body mass index (BMI) and waist circumference (WC) were directly assessed. Covariate-adjusted logistic regression models analyzed the association between cumulative food insecurity experiences and children's body composition. Fifty-eight percent of mothers experienced food insecurity both as a child and as an adult and 31% of the mothers experienced food insecurity either as a child or adult. Maternal cumulative exposure to food insecurity was unrelated to BMI but was negatively related to elevated WC. Although an intergenerational transmission of food insecurity does exist, maternal cumulative exposure to food insecurity does not impact children's body composition negatively in the short term. Studying the long-term effects of cumulative food insecurity exposure can provide information for the development and timing of obesity interventions.
USING CUMULATIVE NUMBER DENSITIES TO COMPARE GALAXIES ACROSS COSMIC TIME
Energy Technology Data Exchange (ETDEWEB)
Behroozi, Peter S.; Wechsler, Risa H. [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Stanford, CA 94305 (United States); Marchesini, Danilo [Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Muzzin, Adam [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Papovich, Casey [Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Stefanon, Mauro [Physics and Astronomy Department, University of Missouri, Columbia, MO 65211 (United States)
2013-11-01
Comparing galaxies across redshifts at fixed cumulative number density is a popular way to estimate the evolution of specific galaxy populations. This method ignores scatter in mass accretion histories and galaxy-galaxy mergers, which can lead to errors when comparing galaxies over large redshift ranges (Δz > 1). We use abundance matching in the ΛCDM paradigm to estimate the median change in cumulative number density with redshift and provide a simple fit (+0.16 dex per unit Δz) for progenitors of z = 0 galaxies. We find that galaxy descendants do not evolve in the same way as galaxy progenitors, largely due to scatter in mass accretion histories. We also provide estimates for the 1σ range of cumulative number densities corresponding to galaxy progenitors and descendants. Finally, we discuss some limits on cumulative number density comparisons, which arise due to difficulties measuring physical quantities (e.g., stellar mass) consistently across redshifts. A public tool to calculate cumulative number density evolution for galaxies, as well as approximate halo masses, is available online.
Maintenance hemodialysis patients have high cumulative radiation exposure.
LENUS (Irish Health Repository)
Kinsella, Sinead M
2010-10-01
Hemodialysis is associated with an increased risk of neoplasms which may result, at least in part, from exposure to ionizing radiation associated with frequent radiographic procedures. In order to estimate the average radiation exposure of those on hemodialysis, we conducted a retrospective study of 100 patients in a university-based dialysis unit followed for a median of 3.4 years. The number and type of radiological procedures were obtained from a central radiology database, and the cumulative effective radiation dose was calculated using standardized, procedure-specific radiation levels. The median annual radiation dose was 6.9 millisieverts (mSv) per patient-year. However, 14 patients had an annual cumulative effective radiation dose over 20 mSv, the upper averaged annual limit for occupational exposure. The median total cumulative effective radiation dose per patient over the study period was 21.7 mSv, in which 13 patients had a total cumulative effective radiation dose over 75 mSv, a value reported to be associated with a 7% increased risk of cancer-related mortality. Two-thirds of the total cumulative effective radiation dose was due to CT scanning. The average radiation exposure was significantly associated with the cause of end-stage renal disease, history of ischemic heart disease, transplant waitlist status, number of in-patient hospital days over follow-up, and death during the study period. These results highlight the substantial exposure to ionizing radiation in hemodialysis patients.
Energy Technology Data Exchange (ETDEWEB)
Goldschmidt, B.
1990-01-01
This book is a memoir of rivalries among the Allies over the bomb, by a participant and observer. Nuclear proliferation began in the uneasy wartime collaboration of the United States, England, Canada, and Free France to produce the atom bomb. Through the changes of history, a young French chemist had a role in almost every act of this international drama. This memoir is based on Goldschmidt's own recollections, interviews with other leading figures, and 3,000 pages of newly declassified documents in Allied archives. From his own start as Marie Curie's lab assistant, Goldschmidt's career was closely intertwined with Frances complicated rise to membership in the nuclear club. As a refugee from the Nazis, he became part of the wartime nuclear energy project in Canada and found himself the only French scientist to work (although briefly) on the American atom bomb project.
Energy Technology Data Exchange (ETDEWEB)
Livingston, A.E.; Kukla, K.; Cheng, S. [Univ. of Toledo, OH (United States)] [and others
1995-08-01
In a collaboration with the Atomic Physics group at Argonne and the University of Toledo, the Atomic Physics group at the University of Notre Dame is measuring the fine structure transition energies in highly-charged lithium-like and helium-like ions using beam-foil spectroscopy. Precise measurements of 2s-2p transition energies in simple (few-electron) atomic systems provide stringent tests of several classes of current atomic- structure calculations. Analyses of measurements in helium-like Ar{sup 16+} have been completed, and the results submitted for publication. A current goal is to measure the 1s2s{sup 3}S{sub 1} - 1s2p{sup 3}P{sub 0} transition wavelength in helium-like Ni{sup 26+}. Measurements of the 1s2s{sup 2}S{sub 1/2} - 1s2p{sup 2}P{sub 1/2,3/2} transition wavelengths in lithium-like Kr{sup 33+} is planned. Wavelength and lifetime measurements in copper-like U{sup 63+} are also expected to be initiated. The group is also participating in measurements of forbidden transitions in helium-like ions. A measurement of the lifetime of the 1s2s{sup 3}S{sub 1} state in Kr{sup 34+} was published recently. In a collaboration including P. Mokler of GSI, Darmstadt, measurements have been made of the spectral distribution of the 2E1 decay continuum in helium-like Kr{sup 34+}. Initial results have been reported and further measurements are planned.
Indian Academy of Sciences (India)
Adya Prasad Mishra; T K Balasubramanian
2001-10-01
Rovibrational matrix elements of the multipole moments ℓ up to rank 10 and of the linear polarizability of the H2 molecule in the condensed phase have been computed taking into account the effect of the intermolecular potential. Comparison with gas phase matrix elements shows that the effect of solid state interactions is marginal.
2015-06-01
Particle-to- Particle (P2P) Graphics Processor Unit (GPU) Kernel for Black-Box Adaptive Fast Multipole Method by Richard H Haney and Dale Shires......ARL-TR-7315 ● JUNE 2015 US Army Research Laboratory Analysis and Implementation of Particle-to- Particle (P2P) Graphics Processor
Meichsner, J
2015-01-01
Perturbations of satellite orbits in the gravitational field of a body with a mass monopole and arbitrary spin multipole moments are considered for an axisymmetric and stationary situation. Periodic and secular effects caused by the central gravitomagnetic field are derived by a first order perturbation theory. For a central spin-dipole field these results reduce to the well known Lense-Thirring effects.
Souza, R de Melo e; Farina, C; Moriconi, M
2008-01-01
We show how to obtain the first multipole contributions to the electromagnetic radiation emited by an arbitrary localized source directly from the Jefimenko equation for the magnetic field and the Panofsky-Phillips equation for the electric field. This procedure avoids the unnecessary calculation of the electromagnetic potentials.
de Melo e Souza, R.; Cougo-Pinto, M. V.; Farina, C.; Moriconi, M.
2009-01-01
We show how to obtain the first multipole contributions to the electromagnetic radiation emitted by an arbitrary localized source directly from the Jefimenko equation for the magnetic field and the Panofsky-Phillips equation for the electric field. This procedure avoids the unnecessary calculation of the electromagnetic potentials.
Cumulative Trauma Among Mayas Living in Southeast Florida.
Millender, Eugenia I; Lowe, John
2016-01-04
Mayas, having experienced genocide, exile, and severe poverty, are at high risk for the consequences of cumulative trauma that continually resurfaces through current fear of an uncertain future. Little is known about the mental health and alcohol use status of this population. This correlational study explored t/he relationship of cumulative trauma as it relates to social determinants of health (years in the United States, education, health insurance status, marital status, and employment), psychological health (depression symptoms), and health behaviors (alcohol use) of 102 Guatemalan Mayas living in Southeast Florida. The results of this study indicated that, as specific social determinants of health and cumulative trauma increased, depression symptoms (particularly among women) and the risk for harmful alcohol use (particularly among men) increased. Identifying risk factors at an early stage before serious disease or problems are manifest provides room for early screening leading to early identification, early treatment, and better outcomes.
Analysis of sensory ratings data with cumulative link models
DEFF Research Database (Denmark)
Christensen, Rune Haubo Bojesen; Brockhoff, Per B.
2013-01-01
Examples of categorical rating scales include discrete preference, liking and hedonic rating scales. Data obtained on these scales are often analyzed with normal linear regression methods or with omnibus Pearson chi2 tests. In this paper we propose to use cumulative link models that allow...... for regression methods similar to linear models while respecting the categorical nature of the observations. We describe how cumulative link models are related to the omnibus chi2 tests and how they can lead to more powerful tests in the non-replicated setting. For replicated categorical ratings data we present...... a quasi-likelihood approach and a mixed effects approach both being extensions of cumulative link models. We contrast population-average and subject-specific interpretations based on these models and discuss how different approaches lead to different tests. In replicated settings, naive tests that ignore...
Cumulative pion production via successive collisions in nuclear medium
Motornenko, A
2016-01-01
Production of pions in proton-nucleus (p+A) reactions outside of a kinematical boundary of proton-nucleon collisions, the so-called cumulative effect, is studied. The kinematical restrictions on pions emitted in backward direction in the target rest frame are analyzed. It is shown that cumulative pion production requires a presence of massive baryonic resonances that are produced during successive collisions of projectile with nuclear nucleons. After each successive collision the mass of created resonance may increase and, simultaneously, its longitudinal velocity decreases. Simulations within Ultra relativistic Quantum Molecular Dynamics model reveals that successive collisions of baryonic resonances with nuclear nucleons plays the dominant role in cumulative pion production in p+A reactions.
Solid-state electro-cumulation effect numerical simulation
Grishin, V G
2001-01-01
It is an attempt to simulate as really as possible a crystal's interatomic interaction under conditions of "Solid-state electro-cumulation (super-polarization) effect". Some theoretical and experimental reasons to believe that within solid substances an interparticles interaction could concentrate from the surface to a centre were given formerly. Now, numerical results show the conditions that could make the cumulation more effective. Another keywords: ion, current, solid, symmetry, cumulation, polarization, depolarization, ionic conductor,superionic conductor, ice, crystal, strain, V-center, V-centre, doped crystal, interstitial impurity, intrinsic color center, high pressure technology, Bridgman, anvil, experiment, crowdion, dielectric, proton, layer, defect, lattice, dynamics, electromigration, mobility, muon catalysis, concentration, doping, dopant, conductivity, pycnonuclear reaction, permittivity, dielectric constant, point defects, interstitials, polarizability, imperfection, defect centers, glass, epi...
Association between diastolic blood pressure and cumulative work time
Directory of Open Access Journals (Sweden)
Ricardo Cordeiro
1999-01-01
Full Text Available Diastolic blood pressure was viewed as a generic indicator of aging, and its association with cumulative work time was studied after controlling for age as a potential confounding factor. The study was conducted among production line workers at a Brazilian tannery in July 1993. The association between diastolic blood pressure and cumulative work time was verified by fitting a second-order linear regression model, where diastolic blood pressure was a function of worker's age and cumulative work time. By fitting the model, one can predict that, in the beginning of working life at the tannery, on average each 1-year period is associated with an increase of about 1.5 mmHg in diastolic blood pressure. The fit obtained highlights one component directly associated with work as part of the rate of pressure increase in the study group. This component is twice as high as that directly associated with age.
Baltic Sea biodiversity status vs. cumulative human pressures
DEFF Research Database (Denmark)
Andersen, Jesper H.; Halpern, Benjamin S.; Korpinen, Samuli
2015-01-01
Abstract Many studies have tried to explain spatial and temporal variations in biodiversity status of marine areas from a single-issue perspective, such as fishing pressure or coastal pollution, yet most continental seas experience a wide range of human pressures. Cumulative impact assessments have...... been developed to capture the consequences of multiple stressors for biodiversity, but the ability of these assessments to accurately predict biodiversity status has never been tested or ground-truthed. This relationship has similarly been assumed for the Baltic Sea, especially in areas with impaired...... status, but has also never been documented. Here we provide a first tentative indication that cumulative human impacts relate to ecosystem condition, i.e. biodiversity status, in the Baltic Sea. Thus, cumulative impact assessments offer a promising tool for informed marine spatial planning, designation...
Session: What do we know about cumulative or population impacts
Energy Technology Data Exchange (ETDEWEB)
Kerlinger, Paul; Manville, Al; Kendall, Bill
2004-09-01
This session at the Wind Energy and Birds/Bats workshop consisted of a panel discussion followed by a discussion/question and answer period. The panelists were Paul Kerlinger, Curry and Kerlinger, LLC, Al Manville, U.S. Fish and Wildlife Service, and Bill Kendall, US Geological Service. The panel addressed the potential cumulative impacts of wind turbines on bird and bat populations over time. Panel members gave brief presentations that touched on what is currently known, what laws apply, and the usefulness of population modeling. Topics addressed included which sources of modeling should be included in cumulative impacts, comparison of impacts from different modes of energy generation, as well as what research is still needed regarding cumulative impacts of wind energy development on bird and bat populations.
Cumulant dynamics in a finite population linkage equilibrium theory
Rattray, M; Rattray, Magnus; Shapiro, Jonathan L.
1999-01-01
The evolution of a finite population at linkage equilibrium is described in terms of the dynamics of phenotype distribution cumulants. This provides a powerful method for describing evolutionary transients and we elucidate the relationship between the cumulant dynamics and the diffusion approximation. A separation of time-scales between the first and higher cumulants for low mutation rates is demonstrated in the diffusion limit and provides a significant simplification of the dynamical system. However, the diffusion limit may not be appropriate for strong selection as the standard Fisher-Wright model of genetic drift can break down in this case. Two novel examples of this effect are considered: we shown that the dynamics may depend on the number of loci under strong directional selection and that environmental variance results in a reduced effective population size. We also consider a simple model of a changing environment which cannot be described by a diffusion equation and we derive the optimal mutation ra...
Effect of correlation on cumulants in heavy-ion collisions
Mishra, D K; Netrakanti, P K
2015-01-01
We study the effects of correlation on cumulants and their ratios of net-proton multiplicity distribution which have been measured for central (0-5\\%) Au+Au collisions at Relativistic Heavy Ion Collider (RHIC). This effect has been studied assuming individual proton and anti-proton distributions as Poisson or Negative Binomial Distribution (NBD). In-spite of significantly correlated production due to baryon number, electric charge conservation and kinematical correlations of protons and anti-protons, the measured cumulants of net-proton distribution follow the independent production model. In the present work we demonstrate how the introduction of correlations will affect the cumulants and their ratios for the difference distributions. We have also demonstrated this study using the proton and anti-proton distributions obtained from HIJING event generator.
Long-range interactions between the alkali-metal atoms and alkaline earth ions
Kaur, Jasmeet; Arora, Bindiya; Sahoo, B K
2014-01-01
Accurate knowledge of interaction potentials among the alkali atoms and alkaline earth ions is very useful in the studies of cold atom physics. Here we carry out theoretical studies of the long-range interactions among the Li, Na, K, and Rb alkali atoms with the Ca$^+$, Ba$^+$, Sr$^+$, and Ra$^+$ alkaline earth ions systematically which are largely motivated by their importance in a number of applications. These interactions are expressed as a power series in the inverse of the internuclear separation $R$. Both the dispersion and induction components of these interactions are determined accurately from the algebraic coefficients corresponding to each power combination in the series. Ultimately, these coefficients are expressed in terms of the electric multipole polarizabilities of the above mentioned systems which are calculated using the matrix elements obtained from a relativistic coupled-cluster method and core contributions to these quantities from the random phase approximation. We also compare our estim...
Angle and Spin Resolved Auger Emission Theory and Applications to Atoms and Molecules
Lohmann, Bernd
2009-01-01
The Auger effect must be interpreted as the radiationless counterpart of photoionization and is usually described within a two-step model. Angle and spin resolved Auger emission physics deals with the theoretical and numerical description, analysis and interpretation of such types of experiments on free atoms and molecules. This monograph derives the general theory applying the density matrix formalism and, in terms of irreducible tensorial sets, so called state multipoles and order parameters, for parameterizing the atomic and molecular systems, respectively. Propensity rules and non-linear dependencies between the angular distribution and spin polarization parameters are included in the discussion. The numerical approaches utilizing relativistic distorted wave (RDWA), multiconfigurational Dirac-Fock (MCDF), and Greens operator methods are described. These methods are discussed and applied to theoretical predictions, numerical results and experimental data for a variety of atomic systems, especially the rare...
System Dynamics and Modified Cumulant Neglect Closure Schemes
DEFF Research Database (Denmark)
Köylüoglu, H. Ugur; Nielsen, Søren R.K.
Dealing with multipeaked problems, the goal of the paper is to improve the quality of the approximations for the expectations appearing in the differential equations written for the statistical moments of the state vector, guided by insight in the system dynamics. For systems with polynomial non......-linearities, modifications in the cumulant neglect closure scheme are suggested. The methodology is illustrated using the two wells oscillator. An error analysis is performed to compare the modified and ordinary cumulant neglect closure schemes applied at the second and fourth order levels with the exact results available....
Baltic Sea biodiversity status vs. cumulative human pressures
DEFF Research Database (Denmark)
Andersen, Jesper H.; Halpern, Benjamin S.; Korpinen, Samuli
2015-01-01
been developed to capture the consequences of multiple stressors for biodiversity, but the ability of these assessments to accurately predict biodiversity status has never been tested or ground-truthed. This relationship has similarly been assumed for the Baltic Sea, especially in areas with impaired...... status, but has also never been documented. Here we provide a first tentative indication that cumulative human impacts relate to ecosystem condition, i.e. biodiversity status, in the Baltic Sea. Thus, cumulative impact assessments offer a promising tool for informed marine spatial planning, designation...
Aspect of cumulative fatigue damage under multiaxial strain cycling.
Zamrik, S. Y.; Tang, P. Y.
1972-01-01
The concept of order of loading and its effect on cumulative fatigue damage under multiaxial strain cyclings was investigated. The effect is illustrated through nonlinear relationships between biaxial fatigue damage and cycle-ratio diagrams. Uniaxial theories such as Miner's method, the convergence method, and the double linear damage rule in its special and generalized form, were examined and extended to the biaxial case through the octahedral shear strain theory. The generalized double linear damage rule was found more applicable to biaxial cumulative fatigue damage.
Cumulative Incidence of Cancer After Solid Organ Transplantation
Hall, Erin C.; Pfeiffer, Ruth M.; Segev, Dorry L.; Engels, Eric A.
2014-01-01
BACKGROUND Solid organ transplantation recipients have elevated cancer incidence. Estimates of absolute cancer risk after transplantation can inform prevention and screening. METHODS The Transplant Cancer Match Study links the US transplantation registry with 14 state/regional cancer registries. The authors used nonparametric competing risk methods to estimate the cumulative incidence of cancer after transplantation for 2 periods (1987–1999 and 2000–2008). For recipients from 2000 to 2008, the 5-year cumulative incidence, stratified by organ, sex, and age at transplantation, was estimated for 6 preventable or screen-detectable cancers. For comparison, the 5-year cumulative incidence was calculated for the same cancers in the general population at representative ages using Surveillance, Epidemiology, and End Results data. RESULTS Among 164,156 recipients, 8520 incident cancers were identified. The absolute cancer risk was slightly higher for recipients during the period from 2000 to 2008 than during the period from 1987 to 1999 (5-year cumulative incidence: 4.4% vs 4.2%; P =.006); this difference arose from the decreasing risk of competing events (5-year cumulative incidence of death, graft failure, or retransplantation: 26.6% vs 31.9%; P 50 years; range, 0.36%–2.22%). For recipients aged >50 years, the 5-year cumulative incidence was higher for colorectal cancer (range, 0.33%–1.94%) than for the general population at the recommended screening age (aged 50 years: range, 0.25%–0.33%). For recipients aged >50 years, the 5-year cumulative incidence was high for lung cancer among thoracic organ recipients (range, 1.16%–3.87%) and for kidney cancer among kidney recipients (range, 0.53%–0.84%). The 5-year cumulative incidence for prostate cancer and breast cancer was similar or lower in transplantation recipients than at the recommended ages of screening in the general population. CONCLUSIONS Subgroups of transplantation recipients have a high absolute risk
A study of cumulative fatigue damage in AISI 4130 steel
Jeelani, S.; Musial, M.
1986-01-01
Experimental data were obtained using AISI 4130 steel under stress ratios of -1 and 0. A study of cumulative fatigue damage using Miner's and Kramer's equations for stress ratios of -1 and 0 for low-high, low-high-mixed, high-low, and high-low-mixed stress sequences has revealed that there is a close agreement between the theoretical and experimental values of fatigue damage and fatigue life. Kramer's equation predicts less conservative and more realistic cumulative fatigue damage than the popularly used Miner's rule does.
Institute of Scientific and Technical Information of China (English)
Dilip Das
2015-01-01
There is a large class of problems in the field of fluid structure interaction where higher-order boundary conditions arise for a second-order partial differential equation. Various methods are being used to tackle these kind of mixed boundary-value problems associated with the Laplace’s equation (or Helmholtz equation) arising in the study of waves propagating through solids or fluids. One of the widely used methods in wave structure interaction is the multipole expansion method. This expansion involves a general combination of a regular wave, a wave source, a wave dipole and a regular wave-free part. The wave-free part can be further expanded in terms of wave-free multipoles which are termed as wave-free potentials. These are singular solutions of Laplace’s equation or two-dimensional Helmholz equation. Construction of these wave-free potentials and multipoles are presented here in a systematic manner for a number of situations such as two-dimensional non-oblique and oblique waves, three dimensional waves in two-layer fluid with free surface condition with higher order partial derivative are considered. In particular, these are obtained taking into account of the effect of the presence of surface tension at the free surface and also in the presence of an ice-cover modelled as a thin elastic plate. Also for limiting case, it can be shown that the multipoles and wave-free potential functions go over to the single layer multipoles and wave-free potential.
The Atomic orbitals of the topological atom
Ramos-Cordoba, Eloy; Salvador Sedano, Pedro
2013-01-01
The effective atomic orbitals have been realized in the framework of Bader's atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These c...
Chen, La; Maybeck, Vanessa; Offenhäusser, Andreas; Krause, Hans-Joachim
2016-06-01
We implemented a novel 2D magnetic twisting cytometry (MTC) based on a previously reported multi-pole high permeability electromagnet, in which both the strength and direction of the twisting field can be controlled. Thanks to the high performance twisting electromagnet and the heterodyning technology, the measurement frequency has been extended to the 1 kHz range. In order to obtain high remanence of the ferromagnetic beads, a separate electromagnet with feedback control was adopted for the high magnetic field polarization. Our setup constitutes the first instrument which can be operated both in MTC mode and in magnetic tweezers (MT) mode. In this work, the mechanical properties of HL-1 cardiomyocytes were characterized in MTC mode. Both anisotropy and log-normal distribution of cell stiffness were observed, which agree with our previous results measured in MT mode. The response from these living cells at different frequencies can be fitted very well by the soft glassy rheology model.
Fajardo, Kristel C Meza; Chaillat, Stéphanie; Lenti, Luca
2016-01-01
In this work, we study seismic wave amplification in alluvial basins having 3D standard geometries through the Fast Multipole Boundary Element Method in the frequency domain. We investigate how much 3D amplification differs from the 1D (horizontal layering) case. Considering incident fields of plane harmonic waves, we examine the relationships between the amplification level and the most relevant physical parameters of the problem (impedance contrast, 3D aspect ratio, vertical and oblique incidence of plane waves). The FMBEM results show that the most important parameters for wave amplification are the impedance contrast and the so-called equivalent shape ratio. Using these two parameters, we derive simple rules to compute the fundamental frequency for various 3D basin shapes and the corresponding 3D/1D amplification factor for 5% damping. Effects on amplification due to 3D basin asymmetry are also studied and incorporated in the derived rules.
Electron Trapping in Multipole Magnet%多极场的电子云俘获效应研究
Institute of Scientific and Technical Information of China (English)
朱雄伟; 国智元
2004-01-01
The electron cloud effect limits the performance of several accelerators with high beam current, such as SLAC and KEK Bfactories, the CERN SPS and the CERN PS. In this paper, the electron trapping in general 2n multipole magnet ( n is integer) isstudied, and we find that there exists electron trapping in the adiabatic region of the multiple magnet ( n＞1 ).%电子云效应限制了几台加速器的高束流密度运行,例如SLAC和KEK的B工厂,CERN的SPS与PS.本文运用辛流形上的1-form李摄动法研究了2n多极场的电子云俘获效应,结果发现在多极磁铁(n＞1)的绝热区存在电子俘获.
Klinkenbusch, Ludger; Brüns, Hendrik
2016-11-01
The paper addresses the combination of the spherical-multipole analysis in sphero-conal coordinates with a uniform complex-source beam (CSB) in order to analyze the scattering of a localized electromagnetic plane wave by any desired part of a perfectly conducting elliptic cone. The concept of uniform CSB is introduced and rigorously applied to the diffraction by a semi-infinite elliptic cone. The analysis takes into account the fact that the incident CSB does not satisfy the radiation condition. A new modal form of the Green's function for the elliptic cone is derived based on the principle that there is no energy loss to infinity. The numerical evaluation includes the scattered far fields of a CSB incident on the corner of a plane angular sector with different opening angles. xml:lang="fr"
Chattaraj, Swarnabha
2016-01-01
We present an analysis of the optical response of a class of on-chip integrated nano-photonic systems comprising all-dielectric building block based multifunctional light manipulating units (LMU) integrated with quantum dot (QD) light sources. The multiple functions (such as focusing excitation light, QD emission rate enhancement, photon guidance, and lossless propagation) are simultaneously realized using the collective Mie resonances of dipole and higher order multipole modes of the dielectric building blocks (DBBs) constituting a single structural unit, the LMU. Using analytical formulation based on Mie theory we demonstrate enhancement of the excitation light simultaneously with the guiding and propagation of the emitted light from a QD emitter integrated with the DBB based LMU. The QD-DBB integrated structures can serve as the basic element for building nano-optical active circuits for optical information processing in both classical and quantum realms.
Kano, Yoshiaki; Kosaka, Takashi; Matsui, Nobuyuki
This paper presents a simple non-linear magnetic analysis-based optimum design of a multi-pole permanent magnet machine as an assistant design tool of 3D-FEM. The proposed analysis is based on the equivalent magnetic circuit and the air gap permeance model between the stator and rotor teeth of the motor, taking into account the local magnetic saturation in the pointed end of teeth. The availability of the proposed analysis is verified by comparing with 3D-FEM analysis from the standpoints of the torque calculation accuracy for the variations of design free parameter and the computation time. After verification, the proposed analysis-based optimum design of the dimensions of permanent magnet is examined, by which the minimization of magnet volume is realized while keeping torque/current ratio at the specified value.
Energy Technology Data Exchange (ETDEWEB)
Papakonstantinou, P. [Technische Univ. Darmstadt (Germany). Inst. fuer Kernphysik]|[Athens Univ. (Greece). Physics Dept., Nuclear and Particle Physics Section; Mavrommatis, E. [Athens Univ. (Greece). Physics Dept., Nuclear and Particle Physics Section; Wambach, J.; Ponomarev, V.Y. [Technische Univ. Darmstadt (Germany). Inst. fuer Kernphysik
2004-12-20
We have used a self-consistent Skyrme-Hartree-Fock plus continuum-RPA model to study the low-multipole response of stable and neutron/proton-rich Ni and Sn isotopes. We focus on the momentum-transfer dependence of the strength distribution, as it provides information on the structure of excited nuclear states and in particular on the variations of the transition form factor (TFF) with the energy. Our results show, among other things, that the TFF may show significant energy dependence in the region of the isoscalar giant monopole resonance and that the TFF corresponding to the threshold strength in the case of neutron-rich nuclei is different compared to the one corresponding to the respective giant resonance. Perspectives are given for more detailed future investigations. (orig.)
Friedrichs, Michael; Brinkmann, Ralf Peter; Oberrath, Jens
2016-09-01
Measuring plasma parameters, e.g. electron density and electron temperature, is an important procedure to verify the stability and behavior of a plasma process. For this purpose the multipole resonance probe (MRP) represents a satisfying solution to measure the electron density. However the influence of the probe on the plasma through its physical presence makes it unattractive for some processes in industrial application. A solution to combine the benefits of the spherical MRP with the ability to integrate the probe into the plasma reactor is introduced by the planar model of the MRP. By coupling the model of the cold plasma with the maxwell equations for electrostatics an analytical model for the admittance of the plasma is derivated, adjusted to cylindrical geometry and solved analytically for the planar MRP using functional analytic methods.
Burt, Eric A.; Tjoelker, R. L.
2007-01-01
A recent long-term comparison between the compensated multi-pole Linear Ion Trap Standard (LITS) and the laser-cooled primary standards via GPS carrier phase time transfer showed a deviation of less than 2.7x10(exp -17)/day. A subsequent evaluation of potential drift contributors in the LITS showed that the leading candidates are fluctuations in background gases and the neon buffer gas. The current vacuum system employs a "flow-through" turbomolecular pump and a diaphragm fore pump. Here we consider the viability of a "sealed" vacuum system pumped by a non-evaporable getter for long-term ultra-stable clock operation. Initial tests suggests that both further stability improvement and longer mean-time-between-maintenance can be achieved using this approach
Chang, Zhe; Wang, Sai; Li, Xin
2011-01-01
Confirmed by the WMAP 7-year results, the quadrupole $C_{\\ell}(\\ell=2)$ moment of the angular power spectrum of the Cosmic Microwave Background(CMB) temperature fluctuations has an anomalously low amplitude compared to the prediction of the standard inflationary scenario and the $\\Lambda$-CDM model. In this paper, we try to take into account the effect of a cosmological-constant type dark energy during the inflation period in the early universe. This is accommodated by a new dispersion relation in a four dimensional de Sitter space, i.e. $\\omega^2= k^2+\\epsilon^{*2}_{\\gamma}$. A modified inflation model of a minimally-coupled scalar field is proposed as a possible dark-energy explanation of the low-$\\ell$ multipole suppression of the CMB spectrum. For $\\epsilon^{*2}_{\\gamma}\\sim 10^{-5} (\\textmd{GeV}^2)$, a smaller theoretical value of $C_{\\ell}(\\ell=2)$ is obtained.
DEFF Research Database (Denmark)
Hansen, Anca Daniela; Michalke, G.
2009-01-01
. A control strategy is presented, which enhances the fault ride-through and voltage support capability of such wind turbines during grid faults. Its design has special focus on power converters' protection and voltage control aspects. The performance of the presented control strategy is assessed......Emphasis in this paper is on the fault ride-through and grid support capabilities of multi-pole permanent magnet synchronous generator (PMSG) wind turbines with a full-scale frequency converter. These wind turbines are announced to be very attractive, especially for large offshore wind farms...... and discussed by means of simulations with the use of a transmission power system generic model developed and delivered by the Danish Transmission System Operator Energinet.dk. The simulation results show how a PMSG wind farm equipped with an additional voltage control can help a nearby active stall wind farm...
Energy Technology Data Exchange (ETDEWEB)
Machicoane, Nathanaël; Cortet, Pierre-Philippe; Moisy, Frédéric [Laboratoire FAST, CNRS, Université Paris-Sud, Orsay (France); Voisin, Bruno [Laboratoire LEGI, CNRS, Université Grenoble Alpes, Grenoble (France)
2015-06-15
We analyze theoretically and experimentally the far-field viscous decay of a two-dimensional inertial wave beam emitted by a harmonic line source in a rotating fluid. By identifying the relevant conserved quantities along the wave beam, we show how the beam structure and decay exponent are governed by the multipole order of the source. Two wavemakers are considered experimentally, a pulsating and an oscillating cylinder, aiming to produce a monopole and a dipole source, respectively. The relevant conserved quantity which discriminates between these two sources is the instantaneous flow rate along the wave beam, which is non-zero for the monopole and zero for the dipole. For each source, the beam structure and decay exponent, measured using particle image velocimetry, are in good agreement with the predictions.
Machicoane, Nathanaël; Voisin, Bruno; Moisy, Frédéric
2015-01-01
We analyze theoretically and experimentally the far-field viscous decay of a two-dimensional inertial wave beam emitted by a harmonic line source in a rotating fluid. By identifying the relevant conserved quantities along the wave beam, we show how the beam structure and decay exponent are governed by the multipole order of the source. Two wavemakers are considered experimentally, a pulsating and an oscillating cylinder, aiming to produce a monopole and a dipole source, respectively. The relevant conserved quantity which discriminates between these two sources is the instantaneous flowrate along the wave beam, which is non-zero for the monopole and zero for the dipole. For each source the beam structure and decay exponent, measured using particle image velocimetry, are in good agreement with the predictions.
Beck, A V Anisovich R; Gottschall, M; Hartmann, J; Kashevarov, V; Klempt, E; Meißner, Ulf-G; Nikonov, V; Ostrick, M; Rönchen, D; Sarantsev, A; Strakovsky, I; Thiel, A; Tiator, L; Thoma, U; Workman, R; Wunderlich, Y
2016-01-01
New data on pion-photoproduction off the proton have been included in the partial wave analyses Bonn-Gatchina and SAID and in the dynamical coupled-channel approach J\\"ulich-Bonn. All reproduce the recent new data well: the double polarization data for E, G, H, P and T in $\\gamma p \\to \\pi^0 p$ from ELSA, the beam asymmetry $\\Sigma$ for $\\gamma p \\to \\pi^0 p$ and $\\pi^+ n$ from Jefferson Laboratory, and the precise new differential cross section and beam asymmetry data $\\Sigma$ for $\\gamma p \\to \\pi^0 p$ from MAMI. The new fit results for the multipoles are compared with predictions not taking into account the new data. The mutual agreement is improved considerably but still far from being perfect.
Sullivan, M.; Caspi, S.; Forest, E.; Robin, D.; Zholents, A.; Cai, Y.; Destaebler, H.; Donald, M.; Helm, R.; Irwin, J.
1994-06-01
The low-energy beam of the proposed PEP-II B factory enters the first quadrupole (Q1) after the interaction point off axis in order to separate the low-energy beam from the high-energy beam. The off-axis beam orbit in Q1 gives rise to significant feed-down terms from higher multipoles that originate from systematic effects and random fabrication errors. The authors study superconducting and permanent magnet designs of Q1, and look at the effect these different designs have on the dynamic aperture. Including a dipole field in a superconducting design allows one to offset the magnetic axis from the mechanical axis, thereby maintaining the separation of the beams while greatly reducing the feed-down effect. They illustrate relevant points of the discussion with tracking results for the PEP-II low-energy ring.
Selection rules for electric multipole transition of diatomic molecule in scattering experiments
Institute of Scientific and Technical Information of China (English)
朱林繁; 田红春; 刘亚伟; 康旭; 刘国兴
2015-01-01
The knowledge of the energy level structures of atoms and molecules is mainly obtained by spectroscopic experiments. Both photoabsorption and photoemission spectra are subject to the electric dipole selection rules (also known as optical selection rules). However, the selection rules for atoms and molecules in the scattering experiments are not identical to those in the optical experiments. In this paper, based on the theory of the molecular point group, the selection rules are derived and summarized for the electric monopole, electric dipole, electric quadrupole, and electric octupole transitions of diatomic molecules under the first Born approximation in scattering experiments. Then based on the derived selection rules, the electron scattering spectra and x-ray scattering spectra of H2, N2, and CO at different momentum transfers are explained, and the discrepancies between the previous experimental results measured by different groups are elucidated.
A Parametric Cumulative Sum Statistic for Person Fit
Armstrong, Ronald D.; Shi, Min
2009-01-01
This article develops a new cumulative sum (CUSUM) statistic to detect aberrant item response behavior. Shifts in behavior are modeled with quadratic functions and a series of likelihood ratio tests are used to detect aberrancy. The new CUSUM statistic is compared against another CUSUM approach as well as traditional person-fit statistics. A…
RECURSIVE CLASSIFICATION OF MQAM SIGNALS BASED ON HIGHER ORDER CUMULANTS
Institute of Scientific and Technical Information of China (English)
Chen Weidong; Yang Shaoquan
2002-01-01
A new feature based on higher order cumulants is proposed for classification of MQAM signals. Theoretical analysis justify that the new feature is invariant with respect to translation (shift), scale and rotation transform of signal constellations, and can suppress color or white additive Gaussian noise. Computer simulation shows that the proposed recursive orderreduction based classification algorithm can classify MQAM signals with any order.
Hierarchical Bayesian parameter estimation for cumulative prospect theory
Nilsson, H.; Rieskamp, J.; Wagenmakers, E.-J.
2011-01-01
Cumulative prospect theory (CPT Tversky & Kahneman, 1992) has provided one of the most influential accounts of how people make decisions under risk. CPT is a formal model with parameters that quantify psychological processes such as loss aversion, subjective values of gains and losses, and
Cumulative psychosocial stress, coping resources, and preterm birth.
McDonald, Sheila W; Kingston, Dawn; Bayrampour, Hamideh; Dolan, Siobhan M; Tough, Suzanne C
2014-12-01
Preterm birth constitutes a significant international public health issue, with implications for child and family well-being. High levels of psychosocial stress and negative affect before and during pregnancy are contributing factors to shortened gestation and preterm birth. We developed a cumulative psychosocial stress variable and examined its association with early delivery controlling for known preterm birth risk factors and confounding environmental variables. We further examined this association among subgroups of women with different levels of coping resources. Utilizing the All Our Babies (AOB) study, an ongoing prospective pregnancy cohort study in Alberta, Canada (n = 3,021), multinomial logistic regression was adopted to examine the independent effect of cumulative psychosocial stress and preterm birth subgroups compared to term births. Stratified analyses according to categories of perceived social support and optimism were undertaken to examine differential effects among subgroups of women. Cumulative psychosocial stress was a statistically significant risk factor for late preterm birth (OR = 1.73; 95 % CI = 1.07, 2.81), but not for early preterm birth (OR = 2.44; 95 % CI = 0.95, 6.32), controlling for income, history of preterm birth, pregnancy complications, reproductive history, and smoking in pregnancy. Stratified analyses showed that cumulative psychosocial stress was a significant risk factor for preterm birth at psychosocial stress on the risk for early delivery.
The proportional odds cumulative incidence model for competing risks
DEFF Research Database (Denmark)
Eriksson, Frank; Li, Jianing; Scheike, Thomas
2015-01-01
We suggest an estimator for the proportional odds cumulative incidence model for competing risks data. The key advantage of this model is that the regression parameters have the simple and useful odds ratio interpretation. The model has been considered by many authors, but it is rarely used in pr...
Is learning in problem-based learning cumulative?
E.H.J. Yew (Elaine); E. Chng (Esther); H.G. Schmidt (Henk)
2011-01-01
textabstractProblem-based learning (PBL) is generally organized in three phases, involving collaborative and self-directed learning processes. The hypothesis tested here is whether learning in the different phases of PBL is cumulative, with learning in each phase depending on that of the previous ph
Cumulative assessment : Strategic choices to influence students' study effort
Kerdijk, Wouter; Tio, Rene A.; Mulder, B. Florentine; Cohen-Schotanus, Janke
2013-01-01
Background: It has been asserted that assessment can and should be used to drive students' learning. In the current study, we present a cumulative assessment program in which test planning, repeated testing and compensation are combined in order to influence study effort. The program is aimed at hel
Repeated mild injury causes cumulative damage to hippocampal cells
E.J. Matser (Amy); C.I. de Zeeuw (Chris); J.T. Weber (John)
2002-01-01
textabstractAn interesting hypothesis in the study of neurotrauma is that repeated traumatic brain injury may result in cumulative damage to cells of the brain. However, post-injury sequelae are difficult to address at the cellular level in vivo. Therefore, it is necessary to compl
The effects of cumulative practice on mathematics problem solving.
Mayfield, Kristin H; Chase, Philip N
2002-01-01
This study compared three different methods of teaching five basic algebra rules to college students. All methods used the same procedures to teach the rules and included four 50-question review sessions interspersed among the training of the individual rules. The differences among methods involved the kinds of practice provided during the four review sessions. Participants who received cumulative practice answered 50 questions covering a mix of the rules learned prior to each review session. Participants who received a simple review answered 50 questions on one previously trained rule. Participants who received extra practice answered 50 extra questions on the rule they had just learned. Tests administered after each review included new questions for applying each rule (application items) and problems that required novel combinations of the rules (problem-solving items). On the final test, the cumulative group outscored the other groups on application and problem-solving items. In addition, the cumulative group solved the problem-solving items significantly faster than the other groups. These results suggest that cumulative practice of component skills is an effective method of training problem solving.
A Parametric Cumulative Sum Statistic for Person Fit
Armstrong, Ronald D.; Shi, Min
2009-01-01
This article develops a new cumulative sum (CUSUM) statistic to detect aberrant item response behavior. Shifts in behavior are modeled with quadratic functions and a series of likelihood ratio tests are used to detect aberrancy. The new CUSUM statistic is compared against another CUSUM approach as well as traditional person-fit statistics. A…
Variable cultural acquisition costs constrain cumulative cultural evolution.
Directory of Open Access Journals (Sweden)
Alex Mesoudi
Full Text Available One of the hallmarks of the human species is our capacity for cumulative culture, in which beneficial knowledge and technology is accumulated over successive generations. Yet previous analyses of cumulative cultural change have failed to consider the possibility that as cultural complexity accumulates, it becomes increasingly costly for each new generation to acquire from the previous generation. In principle this may result in an upper limit on the cultural complexity that can be accumulated, at which point accumulated knowledge is so costly and time-consuming to acquire that further innovation is not possible. In this paper I first review existing empirical analyses of the history of science and technology that support the possibility that cultural acquisition costs may constrain cumulative cultural evolution. I then present macroscopic and individual-based models of cumulative cultural evolution that explore the consequences of this assumption of variable cultural acquisition costs, showing that making acquisition costs vary with cultural complexity causes the latter to reach an upper limit above which no further innovation can occur. These models further explore the consequences of different cultural transmission rules (directly biased, indirectly biased and unbiased transmission, population size, and cultural innovations that themselves reduce innovation or acquisition costs.
Cumulative index 1981-1985, Volumes 138-157.
1985-01-01
This cumulative index also includes listings of all major papers from the American Journal of Neuroradiology, American Journal of Roentgenology, Clinics in Diagnostic Ultrasound, Journal of Computer Assisted Tomography, Journal of Ultrasound in Medicine, RadioGraphics, Radiologic Clinics of North America, Seminars in Nuclear Medicine, Seminars in Roentgenology, and Seminars in Ultrasound, CT and MR.
Cumulative index 1981-1985, Volumes 138-157
Energy Technology Data Exchange (ETDEWEB)
1985-01-01
This cumulative index also includes listings of all major papers from the American Journal of Neuroradiology, American Journal of Roentgenology, Clinics in Diagnostic Ultrasound, Journal of Computer Assisted Tomography, Journal of Ultrasound in Medicine, RadioGraphics, Radiologic Clinics of North America, Seminars in Nuclear Medicine, Seminars in Roentgenology, and Seminars in Ultrasound, CT and MR.
Atom Skimmers and Atom Lasers Utilizing Them
Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.
2005-01-01
Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.
CUMULANTS OF STOCHASTIC RESPONSE FOR A CLASS OF SPECIAL NONHOLONOMIC SYSTEMS
Institute of Scientific and Technical Information of China (English)
SHANG MEI; ZHANG YI
2001-01-01
This paper studies the response cumulants for a kind of special nonholonomic systems under non-Gaussian, delta- correlated excitations. We present a new methodology for formulating the equations governing the evolution of the response cumulants of the stochastic dynamic systems. The response cumulant differential equations (CDEs) derived can be used to calculate the response cumulants for both linear and nonlinear systems. One example is given to illustrate how to use the CDEs for calculating response cumulants.
Correlation effects in double rydberg atoms
Energy Technology Data Exchange (ETDEWEB)
Camus, P. (Lab. Aime Cotton, Centre National de la Recherche Scientifique 2, 91 Orsay (France))
1994-01-01
The present review is devoted to the recent advances performed in alkaline-earth atoms by the selective laser preparation of autoionizing asymmetrical double Rydberg states which have, so far, not been observed in natural environments. Because the great amount of flexibility achieved by the sequential laser electron excitations, a wide choice of two-electron situations have been investigated and analyzed which exhibit spectral features due to long-range effects of the Coulomb electron-electron repulsion. To overcome the autoionization broadening of the lines, double Rydberg states with a non-core penetrating high-l outer electron were produced by combining temporal laser excitation technique with the electric-field switching method. The study of the spectral correlation signatures in N snl double Rydberg states versus l allow to understand their evolution from simple spectra (l [>=] 10) due to long-range dipole interaction to more complex data (l [<=] 7) induced by short-range multipole effects when two electrons start to influence more each other. (orig.).
Schwindt, Peter [Albuquerque, NM; Johnson, Cort N [Albuquerque, NM
2012-07-03
An atomic magnetometer is disclosed which uses a pump light beam at a D1 or D2 transition of an alkali metal vapor to magnetically polarize the vapor in a heated cell, and a probe light beam at a different D2 or D1 transition to sense the magnetic field via a polarization rotation of the probe light beam. The pump and probe light beams are both directed along substantially the same optical path through an optical waveplate and through the heated cell to an optical filter which blocks the pump light beam while transmitting the probe light beam to one or more photodetectors which generate electrical signals to sense the magnetic field. The optical waveplate functions as a quarter waveplate to circularly polarize the pump light beam, and as a half waveplate to maintain the probe light beam linearly polarized.
High Atom Number in Microsized Atom Traps
2015-12-14
Final Performance Report on ONR Grant N00014-12-1-0608 High atom number in microsized atom traps for the period 15 May 2012 through 14 September...TYPE Final Technical Report 3. DATES COVERED (From - To) 05/15/2012-09/14/2012 4. TITLE AND SUBTITLE High atom number in microsized atom traps...forces for implementing a small-footprint, large-number atom -chip instrument. Bichromatic forces rely on absorption and stimulated emission to produce
Detecting Neutral Atoms on an Atom Chip
Wilzbach, M.; Haase, A.; Schwarz, M; Heine, D.; Wicker, K.; Liu, X; Brenner, K. -H.; Groth, S.; Fernholz, Th.; Hessmo, B.; Schmiedmayer, J.
2006-01-01
Detecting single atoms (qubits) is a key requirement for implementing quantum information processing on an atom chip. The detector should ideally be integrated on the chip. Here we present and compare different methods capable of detecting neutral atoms on an atom chip. After a short introduction to fluorescence and absorption detection we discuss cavity enhanced detection of single atoms. In particular we concentrate on optical fiber based detectors such as fiber cavities and tapered fiber d...
A cumulative entropy method for distribution recognition of model error
Liang, Yingjie; Chen, Wen
2015-02-01
This paper develops a cumulative entropy method (CEM) to recognize the most suitable distribution for model error. In terms of the CEM, the Lévy stable distribution is employed to capture the statistical properties of model error. The strategies are tested on 250 experiments of axially loaded CFT steel stub columns in conjunction with the four national building codes of Japan (AIJ, 1997), China (DL/T, 1999), the Eurocode 4 (EU4, 2004), and United States (AISC, 2005). The cumulative entropy method is validated as more computationally efficient than the Shannon entropy method. Compared with the Kolmogorov-Smirnov test and root mean square deviation, the CEM provides alternative and powerful model selection criterion to recognize the most suitable distribution for the model error.
Experience of cumulative effects assessment in the UK
Directory of Open Access Journals (Sweden)
Piper Jake
2004-01-01
Full Text Available Cumulative effects assessment (CEA is a development of environmental impact assessment which attempts to take into account the wider picture of what impacts may affect the environment as a result of either multiple or linear projects, or development plans. CEA is seen as a further valuable tool in promoting sustainable development. The broader canvas upon which the assessment is made leads to a suite of issues such as complexity in methods and assessment of significance, the desirability of co-operation between developers and other parties, new ways of addressing mitigation and monitoring. After outlining the legislative position and the process of CEA, this paper looks at three cases studies in the UK where cumulative assessment has been carried out - the cases concern wind farms, major infrastructure and off-shore developments.
Petrogenesis of the nakhlite meteorites - Evidence from cumulate mineral zoning
Harvey, Ralph P.; Mcsween, Harry Y., Jr.
1992-01-01
Attention is given to a simple igneous petrogenesis for the meteorite Nakhla, which was previously called into question because Mg/Fe ratios in olivine indicate substantial disequilibrium between the predominant cumulus minerals (olivine and augite). Comparative analyses of simulated diffusive zoning and the observed cumulus mineral zoning for all three nakhlites (Nakhla, Governador Valadares, and Lafayette) show that their current compositions do not necessarily reflect parental magma compositions. Diffusion has altered primary cumulus compositions to varying degrees, Nakhla being the least affected, and Lafayette being almost completely reequilibrated. Since mineral zoning in each meteorite is strongly concentric around mesostasis areas, it is inferred that reaction with intercumulus liquid has controlled the observed zoning. It is argued that the nakhlites appear to be a series of relatively simple cumulate rocks which have undergone various amounts of late-magmatic and subsolidus diffusion, possibly reflecting their relative positions in a cooling cumulate pile.
Cumulative dietary exposure of the population of Denmark to pesticides
DEFF Research Database (Denmark)
Jensen, Bodil Hamborg; Petersen, Annette; Nielsen, Elsa
2015-01-01
We used the Hazard Index (HI) method to carry out a cumulative risk assessment after chronic dietary exposure to all monitored pesticides in fruit, vegetables and cereals for various consumer groups in Denmark. Residue data for all the pesticides were obtained from the Danish monitoring programme...... that included processing factors and set non-detects to ½ LOR, but limited the correction (Model 3), gave the most realistic exposure estimate. With Model 3 the HI was calculated to be 0.44 for children and 0.18 for adults, indicating that there is no risk of adverse health effects following chronic cumulative...... exposure to the pesticides found in fruit, vegetables and cereals on the Danish market. The HI was below 1 even for consumers who eat more than 550 g of fruit and vegetables per day, corresponding to 1/3 of the population. Choosing Danish-produced commodities whenever possible could reduce the HI...
Determination of radionuclides and pathways contributing to cumulative dose
Energy Technology Data Exchange (ETDEWEB)
Napier, B.A.
1992-12-01
A series of scoping calculations has been undertaken to evaluate the absolute and relative contributions of different radionuclides and exposure pathways to doses that may have been received by individuals living in the vicinity of the Hanford Site. This scoping calculation (Calculation 004) examined the contributions of numerous radionuclides to cumulative dose via environmental exposures and accumulation in foods. Addressed in this calculation were the contributions to organ and effective dose of infants and adults from (1) air submersion and groundshine external dose, (2) inhalation, (3) ingestion of soil by humans, (4) ingestion of leafy vegetables, (5) ingestion of other vegetables and fruits, (6) ingestion of meat, (7) ingestion of eggs, and (8) ingestion of cows' milk from Feeding Regime 1, as described in calculation 002. This calculation specifically addresses cumulative radiation doses to infants and adults resulting from releases occurring over the period 1945 through 1972.
Cumulative impacts of oil fields on northern alaskan landscapes.
Walker, D A; Webber, P J; Binnian, E F; Everett, K R; Lederer, N D; Nordstrand, E A; Walker, M D
1987-11-06
Proposed further developments on Alaska's Arctic Coastal Plain raise questions about cumulative effects on arctic tundra ecosystems of development of multiple large oil fields. Maps of historical changes to the Prudhoe Bay Oil Field show indirect impacts can lag behind planned developments by many years and the total area eventually disturbed can greatly exceed the planned area of construction. For example, in the wettest parts of the oil field (flat thaw-lake plains), flooding and thermokarst covered more than twice the area directly affected by roads and other construction activities. Protecting critical wildlife habitat is the central issue for cumulative impact analysis in northern Alaska. Comprehensive landscape planning with the use of geographic information system technology and detailed geobotanical maps can help identify and protect areas of high wildlife use.
Effective Carrier Sensing in CSMA Networks under Cumulative Interference
Fu, Liqun; Huang, Jianwei
2009-01-01
This paper proposes and investigates the concept of a safe carrier-sensing range that can guarantee interference safe (also termed hidden-node-free) transmissions in CSMA networks under the cumulative interference model. Compared with the safe carrier-sensing range under the commonly assumed but less realistic pairwise interference model, we show that the safe carrier-sensing range required under the cumulative interference model is larger by a constant multiplicative factor. The concept of a safe carrier-sensing range, although amenable to elegant analytical results, is inherently not compatible with the conventional power threshold carrier-sensing mechanism (e.g., that used in IEEE 802.11). Specifically, the absolute power sensed by a node in the conventional mechanism does not contain enough information for it to derive its distances from other concurrent transmitter nodes. We show that, fortunately, a carrier-sensing mechanism called Incremental-Power Carrier-Sensing (IPCS) can realize the carrier-sensing...
Cumulants and Correlation Functions vs the QCD phase diagram
Bzdak, Adam; Strodthoff, Nils
2016-01-01
In this note we discuss the relation of particle number cumulants and correlation functions related to them. It is argued that measuring couplings of the genuine correlation functions could provide cleaner information on possible non-trivial dynamics in heavy-ion collisions. We extract integrated multi-particle correlation functions from the presently available experimental data on proton cumulants. We find that the STAR data contain significant four-particle correlations, at least at the lower energies, with indication of changing dynamics in central collisions. We also find that these correlations are rather long-ranged in rapidity. Finally based on the signs of genuine correlation functions we provide exclusion plots for the QCD phase diagram.
Cumulants of heat transfer across nonlinear quantum systems
Li, Huanan; Agarwalla, Bijay Kumar; Li, Baowen; Wang, Jian-Sheng
2013-12-01
We consider thermal conduction across a general nonlinear phononic junction. Based on two-time observation protocol and the nonequilibrium Green's function method, heat transfer in steady-state regimes is studied, and practical formulas for the calculation of the cumulant generating function are obtained. As an application, the general formalism is used to study anharmonic effects on fluctuation of steady-state heat transfer across a single-site junction with a quartic nonlinear on-site pinning potential. An explicit nonlinear modification to the cumulant generating function exact up to the first order is given, in which the Gallavotti-Cohen fluctuation symmetry is found still valid. Numerically a self-consistent procedure is introduced, which works well for strong nonlinearity.
Dittrich, Birger; Wandtke, Claudia M; Meents, Alke; Pröpper, Kevin; Mondal, Kartik Chandra; Samuel, Prinson P; Amin Sk, Nurul; Singh, Amit Pratap; Roesky, Herbert W; Sidhu, Navdeep
2015-02-02
Single-crystal X-ray diffraction (XRD) is often considered the gold standard in analytical chemistry, as it allows element identification as well as determination of atom connectivity and the solid-state structure of completely unknown samples. Element assignment is based on the number of electrons of an atom, so that a distinction of neighboring heavier elements in the periodic table by XRD is often difficult. A computationally efficient procedure for aspherical-atom least-squares refinement of conventional diffraction data of organometallic compounds is proposed. The iterative procedure is conceptually similar to Hirshfeld-atom refinement (Acta Crystallogr. Sect. A- 2008, 64, 383-393; IUCrJ. 2014, 1,61-79), but it relies on tabulated invariom scattering factors (Acta Crystallogr. Sect. B- 2013, 69, 91-104) and the Hansen/Coppens multipole model; disordered structures can be handled as well. Five linear-coordinate 3d metal complexes, for which the wrong element is found if standard independent-atom model scattering factors are relied upon, are studied, and it is shown that only aspherical-atom scattering factors allow a reliable assignment. The influence of anomalous dispersion in identifying the correct element is investigated and discussed.
Seasonal climate change patterns due to cumulative CO2 emissions
Partanen, Antti-Ilari; Leduc, Martin; Damon Matthews, H.
2017-07-01
Cumulative CO2 emissions are near linearly related to both global and regional changes in annual-mean surface temperature. These relationships are known as the transient climate response to cumulative CO2 emissions (TCRE) and the regional TCRE (RTCRE), and have been shown to remain approximately constant over a wide range of cumulative emissions. Here, we assessed how well this relationship holds for seasonal patterns of temperature change, as well as for annual-mean and seasonal precipitation patterns. We analyzed an idealized scenario with CO2 concentration growing at an annual rate of 1% using data from 12 Earth system models from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Seasonal RTCRE values for temperature varied considerably, with the highest seasonal variation evident in the Arctic, where RTCRE was about 5.5 °C per Tt C for boreal winter and about 2.0 °C per Tt C for boreal summer. Also the precipitation response in the Arctic during boreal winter was stronger than during other seasons. We found that emission-normalized seasonal patterns of temperature change were relatively robust with respect to time, though they were sub-linear with respect to emissions particularly near the Arctic. Moreover, RTCRE patterns for precipitation could not be quantified robustly due to the large internal variability of precipitation. Our results suggest that cumulative CO2 emissions are a useful metric to predict regional and seasonal changes in precipitation and temperature. This extension of the TCRE framework to seasonal and regional climate change is helpful for communicating the link between emissions and climate change to policy-makers and the general public, and is well-suited for impact studies that could make use of estimated regional-scale climate changes that are consistent with the carbon budgets associated with global temperature targets.
Heavy metal cumulation in crops after the sewage sludge application
Directory of Open Access Journals (Sweden)
Gondová Andrea
1998-12-01
Full Text Available During 1995 - 1996 the crops samples after the sewage sludge application were collected. The heavy metals cumulation in investigated crops from Bardejov increased in order: Zn > Cu > Pb > Ni > Cr > Cd and Banská Bystrica : Zn > Cu > Cr > Ni > Pb > Cd. Heavy metals contents after the sewage sludge application were increased in comparison with the highest admissible concentration in eatable part of crops. The sewage sludge application were not recommended in soils for the growth of vegetables
Finite-volume cumulant expansion in QCD-colorless plasma
Energy Technology Data Exchange (ETDEWEB)
Ladrem, M. [Taibah University, Physics Department, Faculty of Science, Al-Madinah, Al-Munawwarah (Saudi Arabia); Physics Department, Algiers (Algeria); ENS-Vieux Kouba (Bachir El-Ibrahimi), Laboratoire de Physique et de Mathematiques Appliquees (LPMA), Algiers (Algeria); Ahmed, M.A.A. [Taibah University, Physics Department, Faculty of Science, Al-Madinah, Al-Munawwarah (Saudi Arabia); ENS-Vieux Kouba (Bachir El-Ibrahimi), Laboratoire de Physique et de Mathematiques Appliquees (LPMA), Algiers (Algeria); Taiz University in Turba, Physics Department, Taiz (Yemen); Alfull, Z.Z. [Taibah University, Physics Department, Faculty of Science, Al-Madinah, Al-Munawwarah (Saudi Arabia); Cherif, S. [ENS-Vieux Kouba (Bachir El-Ibrahimi), Laboratoire de Physique et de Mathematiques Appliquees (LPMA), Algiers (Algeria); Ghardaia University, Sciences and Technologies Department, Ghardaia (Algeria)
2015-09-15
Due to the finite-size effects, the localization of the phase transition in finite systems and the determination of its order, become an extremely difficult task, even in the simplest known cases. In order to identify and locate the finite-volume transition point T{sub 0}(V) of the QCD deconfinement phase transition to a colorless QGP, we have developed a new approach using the finite-size cumulant expansion of the order parameter and the L{sub mn}-method. The first six cumulants C{sub 1,2,3,4,5,6} with the corresponding under-normalized ratios (skewness Σ, kurtosis κ, pentosis Π{sub ±}, and hexosis H{sub 1,2,3}) and three unnormalized combinations of them, (O = σ{sup 2}κΣ{sup -1},U = σ{sup -2}Σ{sup -1},N = σ{sup 2}κ) are calculated and studied as functions of (T, V). A new approach, unifying in a clear and consistent way the definitions of cumulant ratios, is proposed.Anumerical FSS analysis of the obtained results has allowed us to locate accurately the finite-volume transition point. The extracted transition temperature value T{sub 0}(V) agrees with that expected T{sub 0}{sup N}(V) from the order parameter and the thermal susceptibility χ{sub T} (T, V), according to the standard procedure of localization to within about 2%. In addition to this, a very good correlation factor is obtained proving the validity of our cumulants method. The agreement of our results with those obtained by means of other models is remarkable. (orig.)
The cumulation of methylmercury in fish (Poecilia reticulata)
Energy Technology Data Exchange (ETDEWEB)
Stary, J.; Kratzer, K.; Havlik, B.; Prasilova, J.; Hanusova, J.
1980-01-01
Methylmercury labelled with mercury-203 was used for the investigation of the uptake and the release of methylmercury in fish. It has been found that methylmercury compounds adsorbed on fish food remain completely in fish and that they are released with the biological half-time of 110 days. The cumulation of methylmercury from water is very rapid. Equations for the calculation of the concentration of methylmercury in fish were derived and compared with the uptake of phenylmercury and inorganic mercury.
Erupted cumulate fragments in rhyolites from Lipari (Aeolian Islands)
Forni, Francesca; Ellis, Ben S.; Bachmann, Olivier; Lucchi, Federico; Tranne, Claudio A.; Agostini, Samuele; Dallai, Luigi
2015-12-01
Over the last ~267 ky, the island of Lipari has erupted magmas ranging in compositions from basaltic andesites to rhyolites, with a notable compositional gap in the dacite field. Bulk geochemical and isotopic compositions of the volcanic succession, in conjunction with major and trace elemental compositions of minerals, indicate that the rhyolites were dominantly generated via crystal fractionation processes, with subordinate assimilation. Radiogenic (Sr, Nd, and Pb) and stable (O) isotopes independently suggest ≤30 % of crustal contamination with the majority of it occurring in mafic compositions, likely relatively deep in the system. Within the rhyolites, crystal-rich, K2O-rich enclaves are common. In contrast to previous interpretations, we suggest that these enclaves represent partial melting, remobilization and eruption of cumulate fragments left-over from rhyolite melt extraction. Cumulate melting and remobilization is supported by the presence of (1) resorbed, low-temperature minerals (biotite and sanidine), providing the potassic signature to these clasts, (2) reacted Fo-rich olivine, marking the presence of mafic recharge, (3) An38-21 plagioclase, filling the gap in feldspar composition between the andesites and the rhyolites and (4) strong enrichment in Sr and Ba in plagioclase and sanidine, suggesting crystallization from a locally enriched melt. Based on Sr-melt partitioning, the high-Sr plagioclase would require ~2300 ppm Sr in the melt, a value far in excess of Sr contents in Lipari and Vulcano magmas (50-1532 ppm) but consistent with melting of a feldspar-rich cumulate. Due to the presence of similar crystal-rich enclaves within the rhyolites from Vulcano, we propose that the eruption of remobilized cumulates associated with high-SiO2 rhyolites may be a common process at the Aeolian volcanoes, as already attested for a variety of volcanic systems around the world.
[Cumulative effect of Coriolis acceleration on coronary hemodynamics].
Lapaev, E V; Bednenko, V S
1985-01-01
Time-course variations in coronary circulation and cardiac output were measured in 29 healthy test subjects who performed tests with a continuous cumulation of Coriolis accelerations and in 12 healthy test subjects who were exposed to Coriolis accelerations combined with acute hypoxia. Adaptive changes in coronary circulation were seen. It is recommended to monitor coronary circulation during vestibulometric tests as part of medical expertise of the flying personnel.
Cumulative Risk Assessment Toolbox: Methods and Approaches for the Practitioner
Directory of Open Access Journals (Sweden)
Margaret M. MacDonell
2013-01-01
Full Text Available The historical approach to assessing health risks of environmental chemicals has been to evaluate them one at a time. In fact, we are exposed every day to a wide variety of chemicals and are increasingly aware of potential health implications. Although considerable progress has been made in the science underlying risk assessments for real-world exposures, implementation has lagged because many practitioners are unaware of methods and tools available to support these analyses. To address this issue, the US Environmental Protection Agency developed a toolbox of cumulative risk resources for contaminated sites, as part of a resource document that was published in 2007. This paper highlights information for nearly 80 resources from the toolbox and provides selected updates, with practical notes for cumulative risk applications. Resources are organized according to the main elements of the assessment process: (1 planning, scoping, and problem formulation; (2 environmental fate and transport; (3 exposure analysis extending to human factors; (4 toxicity analysis; and (5 risk and uncertainty characterization, including presentation of results. In addition to providing online access, plans for the toolbox include addressing nonchemical stressors and applications beyond contaminated sites and further strengthening resource accessibility to support evolving analyses for cumulative risk and sustainable communities.
Finite Volume Cumulant Expansion in QCD-Colorless Plasma
Ladrem, M; Al-Full, Z; Cherif, S
2015-01-01
Due to the finite size effects, the localisation of the phase transition in finite systems and the determination of its order, become an extremely difficult task, even in the simplest known cases. In order to identify and locate the finite volume transition point $T_{0}(V)$ of the QCD deconfinement phase transition to a Colorless QGP, we have developed a new approach using the finite size cumulant expansion of the order parameter and the $L_{mn}$-method. The first six cumulants $C_{1,2,3,4,5,6}$ with the corresponding under-normalized ratios(skewness $\\Sigma$, kurtosis $\\kappa$ ,pentosis $\\Pi_{\\pm}$ and hexosis $\\mathcal{H}_{1,2,3}$) and three unnormalized combinations of them ($\\mathcal{O}={\\mathcal{\\sigma }^{2} \\mathcal{\\kappa } }{\\mathbf{\\Sigma }^{-1} }$, $\\mathcal{U} ={\\mathcal{\\sigma }^{-2} \\mathbf{\\Sigma }^{-1} }$, $\\mathcal{N} = \\mathcal{\\sigma }^{2} \\mathcal{\\kappa }$) are calculated and studied as functions of $(T,V)$. A new approach, unifying in a clear and consistent way the definitions of cumulant...
Cumulative Risk Assessment Toolbox: Methods and Approaches for the Practitioner
MacDonell, Margaret M.; Haroun, Lynne A.; Teuschler, Linda K.; Rice, Glenn E.; Hertzberg, Richard C.; Butler, James P.; Chang, Young-Soo; Clark, Shanna L.; Johns, Alan P.; Perry, Camarie S.; Garcia, Shannon S.; Jacobi, John H.; Scofield, Marcienne A.
2013-01-01
The historical approach to assessing health risks of environmental chemicals has been to evaluate them one at a time. In fact, we are exposed every day to a wide variety of chemicals and are increasingly aware of potential health implications. Although considerable progress has been made in the science underlying risk assessments for real-world exposures, implementation has lagged because many practitioners are unaware of methods and tools available to support these analyses. To address this issue, the US Environmental Protection Agency developed a toolbox of cumulative risk resources for contaminated sites, as part of a resource document that was published in 2007. This paper highlights information for nearly 80 resources from the toolbox and provides selected updates, with practical notes for cumulative risk applications. Resources are organized according to the main elements of the assessment process: (1) planning, scoping, and problem formulation; (2) environmental fate and transport; (3) exposure analysis extending to human factors; (4) toxicity analysis; and (5) risk and uncertainty characterization, including presentation of results. In addition to providing online access, plans for the toolbox include addressing nonchemical stressors and applications beyond contaminated sites and further strengthening resource accessibility to support evolving analyses for cumulative risk and sustainable communities. PMID:23762048
4D Near-Field Source Localization Using Cumulant
Directory of Open Access Journals (Sweden)
Zhao Feng
2007-01-01
Full Text Available This paper proposes a new cumulant-based algorithm to jointly estimate four-dimensional (4D source parameters of multiple near-field narrowband sources. Firstly, this approach proposes a new cross-array, and constructs five high-dimensional Toeplitz matrices using the fourth-order cumulants of some properly chosen sensor outputs; secondly, it forms a parallel factor (PARAFAC model in the cumulant domain using these matrices, and analyzes the unique low-rank decomposition of this model; thirdly, it jointly estimates the frequency, two-dimensional (2D directions-of-arrival (DOAs, and range of each near-field source from the matrices via the low-rank three-way array (TWA decomposition. In comparison with some available methods, the proposed algorithm, which efficiently makes use of the array aperture, can localize sources using sensors. In addition, it requires neither pairing parameters nor multidimensional search. Simulation results are presented to validate the performance of the proposed method.
4D Near-Field Source Localization Using Cumulant
Directory of Open Access Journals (Sweden)
Junying Zhang
2007-01-01
Full Text Available This paper proposes a new cumulant-based algorithm to jointly estimate four-dimensional (4D source parameters of multiple near-field narrowband sources. Firstly, this approach proposes a new cross-array, and constructs five high-dimensional Toeplitz matrices using the fourth-order cumulants of some properly chosen sensor outputs; secondly, it forms a parallel factor (PARAFAC model in the cumulant domain using these matrices, and analyzes the unique low-rank decomposition of this model; thirdly, it jointly estimates the frequency, two-dimensional (2D directions-of-arrival (DOAs, and range of each near-field source from the matrices via the low-rank three-way array (TWA decomposition. In comparison with some available methods, the proposed algorithm, which efficiently makes use of the array aperture, can localize N−3 sources using N sensors. In addition, it requires neither pairing parameters nor multidimensional search. Simulation results are presented to validate the performance of the proposed method.
Cumulative risk: toxicity and interactions of physical and chemical stressors.
Rider, Cynthia V; Boekelheide, Kim; Catlin, Natasha; Gordon, Christopher J; Morata, Thais; Selgrade, Maryjane K; Sexton, Kenneth; Simmons, Jane Ellen
2014-01-01
Recent efforts to update cumulative risk assessment procedures to incorporate nonchemical stressors ranging from physical to psychosocial reflect increased interest in consideration of the totality of variables affecting human health and the growing desire to develop community-based risk assessment methods. A key roadblock is the uncertainty as to how nonchemical stressors behave in relationship to chemical stressors. Physical stressors offer a reasonable starting place for measuring the effects of nonchemical stressors and their modulation of chemical effects (and vice versa), as they clearly differ from chemical stressors; and "doses" of many physical stressors are more easily quantifiable than those of psychosocial stressors. There is a commonly held belief that virtually nothing is known about the impact of nonchemical stressors on chemically mediated toxicity or the joint impact of coexposure to chemical and nonchemical stressors. Although this is generally true, there are several instances where a substantial body of evidence exists. A workshop titled "Cumulative Risk: Toxicity and Interactions of Physical and Chemical Stressors" held at the 2013 Society of Toxicology Annual Meeting provided a forum for discussion of research addressing the toxicity of physical stressors and what is known about their interactions with chemical stressors, both in terms of exposure and effects. Physical stressors including sunlight, heat, radiation, infectious disease, and noise were discussed in reference to identifying pathways of interaction with chemical stressors, data gaps, and suggestions for future incorporation into cumulative risk assessments.
Childhood poverty and health: cumulative risk exposure and stress dysregulation.
Evans, Gary W; Kim, Pilyoung
2007-11-01
A massive literature documents the inverse association between poverty or low socioeconomic status and health, but little is known about the mechanisms underlying this robust relation. We examined longitudinal relations between duration of poverty exposure since birth, cumulative risk exposure, and physiological stress in two hundred seven 13-year-olds. Chronic stress was assessed by basal blood pressure and overnight cortisol levels; stress regulation was assessed by cardiovascular reactivity to a standard acute stressor and recovery after exposure to this stressor. Cumulative risk exposure was measured by multiple physical (e.g., substandard housing) and social (e.g., family turmoil) risk factors. The greater the number of years spent living in poverty, the more elevated was overnight cortisol and the more dysregulated was the cardiovascular response (i.e., muted reactivity). Cardiovascular recovery was not affected by duration of poverty exposure. Unlike the duration of poverty exposure, concurrent poverty (i.e., during adolescence) did not affect these physiological stress outcomes. The effects of childhood poverty on stress dysregulation are largely explained by cumulative risk exposure accompanying childhood poverty.
Multiway Filtering Based on Fourth-Order Cumulants
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Salah Bourennane
2005-05-01
Full Text Available We propose a new multiway filtering based on fourth-order cumulants for the denoising of noisy data tensor with correlated Gaussian noise. The classical multiway filtering is based on the TUCKALS3 algorithm that computes a lower-rank tensor approximation. The presented method relies on the statistics of the analyzed multicomponent signal. We first recall how the well-known lower rank-(K1,Ã¢Â€Â¦,KN tensor approximation processed by TUCKALS3 alternating least square algorithm exploits second-order statistics. Then, we propose to introduce the fourth-order statistics in the TUCKALS3-based method. Indeed, the use of fourth-order cumulants enables to remove the Gaussian components of an additive noise. In the presented method the estimation of the n-mode projector on the n-mode signal subspace are built from the eigenvectors associated with the largest eigenvalues of a fourth-order cumulant slice matrix instead of a covariance matrix. Each projector is applied by means of the n-mode product operator on the n-mode of the data tensor. The qualitative results of the improved multiway TUCKALS3-based filterings are shown for the case of noise reduction in a color image and multicomponent seismic data.
Cumulative risk hypothesis: Predicting and preventing child maltreatment recidivism.
Solomon, David; Åsberg, Kia; Peer, Samuel; Prince, Gwendolyn
2016-08-01
Although Child Protective Services (CPS) and other child welfare agencies aim to prevent further maltreatment in cases of child abuse and neglect, recidivism is common. Having a better understanding of recidivism predictors could aid in preventing additional instances of maltreatment. A previous study identified two CPS interventions that predicted recidivism: psychotherapy for the parent, which was related to a reduced risk of recidivism, and temporary removal of the child from the parent's custody, which was related to an increased recidivism risk. However, counter to expectations, this previous study did not identify any other specific risk factors related to maltreatment recidivism. For the current study, it was hypothesized that (a) cumulative risk (i.e., the total number of risk factors) would significantly predict maltreatment recidivism above and beyond intervention variables in a sample of CPS case files and that (b) therapy for the parent would be related to a reduced likelihood of recidivism. Because it was believed that the relation between temporary removal of a child from the parent's custody and maltreatment recidivism is explained by cumulative risk, the study also hypothesized that that the relation between temporary removal of the child from the parent's custody and recidivism would be mediated by cumulative risk. After performing a hierarchical logistic regression analysis, the first two hypotheses were supported, and an additional predictor, psychotherapy for the child, also was related to reduced chances of recidivism. However, Hypothesis 3 was not supported, as risk did not significantly mediate the relation between temporary removal and recidivism.
Energy Technology Data Exchange (ETDEWEB)
Crespillo, M.L., E-mail: mcrespil@utk.edu [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain); Department of Materials Science & Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Agulló-López, F., E-mail: fal@uam.es [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain); Zucchiatti, A. [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain)
2017-03-01
Highlights: • Extensive survey formation energies Frenkel pairs and electronic stopping thresholds. • Correlation: track formation thresholds and the energies for Frenkel pair formation. • Formation energies Frenkel pairs discussed in relation to the cumulative mechanisms. • Amorphous track formation mechanisms: defect accumulation models versus melting. • Advantages cumulative models to deal with new hot topics: nuclear-electronic synergy. - Abstract: An extensive survey for the formation energies of Frenkel pairs, as representative candidates for radiation-induced point defects, is presented and discussed in relation to the cumulative mechanisms (CM) of track formation in dielectric materials under swift heavy ion (SHI) irradiation. These mechanisms rely on the generation and accumulation of point defects during irradiation followed by collapse of the lattice once a threshold defect concentration is reached. The physical basis of those approaches has been discussed by Fecht as a defect-assisted transition to an amorphous phase. Although a first quantitative analysis of the CM model was previously performed for LiNbO{sub 3} crystals, we have, here, adopted a broader phenomenological approach. It explores the correlation between track formation thresholds and the energies for Frenkel pair formation for a broad range of materials. It is concluded that the threshold stopping powers can be roughly scaled with the energies required to generate a critical Frenkel pair concentration in the order of a few percent of the total atomic content. Finally, a comparison with the predictions of the thermal spike model is discussed within the analytical Szenes approximation.
Zhuo, Congshan; Sagaut, Pierre
2017-06-01
In this paper, a variant of the acoustic multipole source (AMS) method is proposed within the framework of the lattice Boltzmann method. A quadrupole term is directly included in the stress system (equilibrium momentum flux), and the dependency of the quadrupole source in the inviscid limit upon the fortuitous discretization error reported in the works of E. M. Viggen [Phys. Rev. E 87, 023306 (2013)PLEEE81539-375510.1103/PhysRevE.87.023306] is removed. The regularized lattice Boltzmann (RLB) method with this variant AMS method is presented for the 2D and 3D acoustic problems in the inviscid limit, and without loss of generality, the D3Q19 model is considered in this work. To assess the accuracy and the advantage of the RLB scheme with this AMS for acoustic point sources, the numerical investigations and comparisons with the multiple-relaxation-time (MRT) models and the analytical solutions are performed on the 2D and 3D acoustic multipole point sources in the inviscid limit, including monopoles, x dipoles, and xx quadrupoles. From the present results, the good precision of this AMS method is validated, and the RLB scheme exhibits some superconvergence properties for the monopole sources compared with the MRT models, and both the RLB and MRT models have the same accuracy for the simulations of acoustic dipole and quadrupole sources. To further validate the capability of the RLB scheme with AMS, another basic acoustic problem, the acoustic scattering from a solid cylinder presented at the Second Computational Aeroacoustics Workshop on Benchmark Problems, is numerically considered. The directivity pattern of the acoustic field is computed at r=7.5; the present results agree well with the exact solutions. Also, the effects of slip and no-slip wall treatments within the regularized boundary condition on this pure acoustic scattering problem are tested, and compared with the exact solution, the slip wall treatment can present a better result. All simulations demonstrate
Willden, Jeff
2001-01-01
"Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…
The atomic orbitals of the topological atom.
Ramos-Cordoba, Eloy; Salvador, Pedro; Mayer, István
2013-06-07
The effective atomic orbitals have been realized in the framework of Bader's atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These correspond to atomic hybrids that closely resemble the core and valence shells of the atom. The occupation numbers of the remaining effective orbitals are almost negligible, except for atoms with hypervalent character. In addition, the molecular orbitals of a calculation can be exactly expressed as a linear combination of this orthonormalized set of numerical atomic orbitals, and the Mulliken population analysis carried out on this basis set exactly reproduces the original QTAIM atomic populations of the atoms. Approximate expansion of the molecular orbitals over a much reduced set of orthogonal atomic basis functions can also be accomplished to a very good accuracy with a singular value decomposition procedure.
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Dugand Armando
1944-03-01
Full Text Available Nombres vulgares: Carreto (Atlántico, Bolívar, Magdalena; Cumulá, Cumulá (Cundinamarca, ToIima. Según el Dr. Emilio Robledo (Lecciones de Bot. ed. 3, 2: 544. 1939 el nombre Carreto también es empleado en Puerto Berrío (Antioquia. El mismo autor (loc. cit. da el nombre Comulá para una especie indeterminada de Viburnum en Mariquita (Tolima y J. M. Duque, refiriendose a la misma planta y localidad (en Bot. Gen. Colomb. 340, 356. 1943 atribuye este nombre vulgar al Aspidosperma ellipticum Rusby. Sin embargo, las muestras de madera de Cumulá o Comulá que yo he examinado, procedentes de la región de Mariquita -una de las cuales me fue recientemente enviada por el distinguido ictiólogo Sr. Cecil Miles- pertenecen sin duda alguna al A. Dugandii StandI. Por otra parte, Santiago Cortés (FI. Colomb. 206. 1898; ed, 2: 239. 1912 cita el Cumulá "de Anapoima y otros lugares del (rio Magdalena" diciendo que pertenece a las Leguminosas, pero la brevísima descripción que este autor hace de la madera "naranjada y notable por densidad, dureza y resistencia a la humedad", me induce a creer que se trata del mismo Cumula coleccionado recientemente en Tocaima, ya que esta población esta situada a pocos kilómetros de Anapoima. Nombres vulgares: Carreto (Atlántico, Bolívar, Magdalena; Cumulá, Cumulá (Cundinamarca, ToIima. Según el Dr. Emilio Robledo (Lecciones de Bot. ed. 3, 2: 544. 1939 el nombre Carreto también es empleado en Puerto Berrío (Antioquia. El mismo autor (loc. cit. da el nombre Comulá para una especie indeterminada de Viburnum en Mariquita (Tolima y J. M. Duque, refiriendose a la misma planta y localidad (en Bot. Gen. Colomb. 340, 356. 1943 atribuye este nombre vulgar al Aspidosperma ellipticum Rusby. Sin embargo, las muestras de madera de Cumulá o Comulá que yo he examinado, procedentes de la región de Mariquita -una de las cuales me fue recientemente enviada por el distinguido ictiólogo Sr. Cecil Miles- pertenecen sin
Fast multipole boundary element method for Helmholtz equation problems%Helmholtz方程问题的快速多极边界元求解方法
Institute of Scientific and Technical Information of China (English)
于海源; 陈一鸣; 于春肖
2012-01-01
In order to overcome the difficulties of low computational efficiency and high memory requirement in the conventional boundary element method for solving large-scale Helmholtz equation problems, a fast multipole boundary element method for the problems of Helmholtz equation is presented. Two theorems are obtained based on the multipole expansion and the local expansion of the boundary element method fundamental solutions'Kernel function. What's more, the basic formulas and the main steps of the fast multipole boundary element method are described for 2D and 3D Helmholtz equation problems.%为了改善传统边界元在求解大规模Helmholtz方程的实际问题时计算效率低、存储量大的缺点,针对快速多极边界元法求解Helmholtz方程进行了理论分析.通过对二维和三维Helmholtz方程的基本解的核函数进行多极展开和局部展开,得到了相应的展开定理,并基于展开定理分别推导了二维和三维问题Helmholtz方程的快速多极边界元计算公式,给出了快速多极边界元法求解Helmholtz方程的主要计算步骤.
Domagała, Sławomir; Fournier, Bertrand; Liebschner, Dorothee; Guillot, Benoît; Jelsch, Christian
2012-05-01
ELMAM2 is a generalized and improved library of experimentally derived multipolar atom types. The previously published ELMAM database is restricted mostly to protein atoms. The current database is extended to common functional groups encountered in organic molecules and is based on optimized local axes systems taking into account the local pseudosymmetry of the molecular fragment. In this approach, the symmetry-restricted multipoles have zero populations, while others take generally significant values. The various applications of the database are described. The deformation electron densities, electrostatic potentials and interaction energies calculated for several tripeptides and aromatic molecules are calculated using ELMAM2 electron-density parameters and compared with the former ELMAM database and density functional theory calculations.
Lin, Jeffrey; Scalo, Carlo; Hesselink, Lambertus
2015-11-01
We have carried out the first high-fidelity Navier-Stokes simulation of a complete thermoacoustic engine with piezoelectric energy extraction. The standing-wave thermoacoustic piezoelectric (TAP) engine model comprises a 51 cm long cylindrical resonator, containing a thermoacoustic stack on one end and capped by a PZT-5A piezoelectric diaphragm on the other end, tuned to the frequency of the thermoacoustically-amplified mode (388 Hz). A multi-pole broadband time-domain impedance model has been adopted to accurately simulate the measured electromechanical properties of the piezoelectric diaphragm. Simulations are first carried out from quasi-quiescent conditions to a limit cycle, with varying temperature gradients and stack configurations. Stack geometry and boundary layers are fully resolved. Acoustic energy extraction is then activated, achieving a new limit cycle at lower pressure amplitudes. The scaling of the modeled electrical power output and attainable thermal-to-electric energy conversion efficiencies are discussed. Limitations of extending a quasi-one-dimensional linear approximation based on Rott's theory to a (low amplitude) limit cycle are discussed, as well as nonlinear effects such as thermoacoustic energy transport and viscous dissipation.
Michálek, Tomáš; Zemánek, Jiří
2017-03-16
Mathematical models of dielectrophoresis play an important role in the design of experiments, analysis of results, and even operation of some devices. In this paper, we test the accuracy of existing models in both simulations and laboratory experiments. We test the accuracy of the most common model that involves a point-dipole approximation of the induced field, when the small-particle assumption is broken. In simulations, comparisons against a model based on the Maxwell stress tensor show that even the point-dipole approximation provides good results for a large particle close to the electrodes. In addition, we study a refinement of the model offered by multipole approximations (quadrupole, and octupole). We also show that the voltages on the electrodes influence the error of the model because they affect the positions of the field nulls and the nulls of the higher-order derivatives. Experiments with a parallel electrode array and a polystyrene microbead reveal that the models predict the force with an error that cannot be eliminated even with the most accurate model. Nonetheless, it is acceptable for some purposes such as a model-based control system design. This article is protected by copyright. All rights reserved.
Ren, Zhengyong; Tang, Jingtian; Kalscheuer, Thomas; Maurer, Hansruedi
2017-01-01
A novel fast and accurate algorithm is developed for large-scale 3-D gravity and magnetic modeling problems. An unstructured grid discretization is used to approximate sources with arbitrary mass and magnetization distributions. A novel adaptive multilevel fast multipole (AMFM) method is developed to reduce the modeling time. An observation octree is constructed on a set of arbitrarily distributed observation sites, while a source octree is constructed on a source tetrahedral grid. A novel characteristic is the independence between the observation octree and the source octree, which simplifies the implementation of different survey configurations such as airborne and ground surveys. Two synthetic models, a cubic model and a half-space model with mountain-valley topography, are tested. As compared to analytical solutions of gravity and magnetic signals, excellent agreements of the solutions verify the accuracy of our AMFM algorithm. Finally, our AMFM method is used to calculate the terrain effect on an airborne gravity data set for a realistic topography model represented by a triangular surface retrieved from a digital elevation model. Using 16 threads, more than 5800 billion interactions between 1,002,001 observation points and 5,839,830 tetrahedral elements are computed in 453.6 s. A traditional first-order Gaussian quadrature approach requires 3.77 days. Hence, our new AMFM algorithm not only can quickly compute the gravity and magnetic signals for complicated problems but also can substantially accelerate the solution of 3-D inversion problems.
Mismatch or cumulative stress : Toward an integrated hypothesis of programming effects
Nederhof, Esther; Schmidt, Mathias V.
2012-01-01
This paper integrates the cumulative stress hypothesis with the mismatch hypothesis, taking into account individual differences in sensitivity to programming. According to the cumulative stress hypothesis, individuals are more likely to suffer from disease as adversity accumulates. According to the
Institute of Scientific and Technical Information of China (English)
LI Shichun
2004-01-01
Based on the Thomas-Fermi-Dirac-Cheng model, atomic phase diagram or electron density versus atomic radius diagram describing the interaction properties of atoms of different kinds in equilibrium state is developed. Atomic phase diagram is established based on the two-atoms model. Besides atomic radius, electron density and continuity condition for electron density on interfaces between atoms, the lever law of atomic phase diagram involving other physical parameters is taken into account, such as the binding energy, for the sake of simplicity.
Mapping cumulative noise from shipping to inform marine spatial planning.
Erbe, Christine; MacGillivray, Alexander; Williams, Rob
2012-11-01
Including ocean noise in marine spatial planning requires predictions of noise levels on large spatiotemporal scales. Based on a simple sound transmission model and ship track data (Automatic Identification System, AIS), cumulative underwater acoustic energy from shipping was mapped throughout 2008 in the west Canadian Exclusive Economic Zone, showing high noise levels in critical habitats for endangered resident killer whales, exceeding limits of "good conservation status" under the EU Marine Strategy Framework Directive. Error analysis proved that rough calculations of noise occurrence and propagation can form a basis for management processes, because spending resources on unnecessary detail is wasteful and delays remedial action.
The Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS) trial.
Eichhorn, Eric J; Bristow, Michael R
2001-01-01
Previous trials (Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure [MERIT-HF], Cardiac Insufficiency Bisoprolol Study [CIBIS] II) have demonstrated a mortality benefit of beta-adrenergic blockade in patients with mild to moderate heart failure. The recent Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS) trial has extended these results to a more advanced patient population. This trial did not, however, include patients who could not reach compensation, patients with far advanced heart failure symptoms, or a significant number of black patients. Future studies of beta-blockade may focus on these patients or patients with asymptomatic left ventricular dysfunction.
The Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS trial
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Bristow Michael R
2001-02-01
Full Text Available Abstract Previous trials (Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure [MERIT-HF], Cardiac Insufficiency Bisoprolol Study [CIBIS] II have demonstrated a mortality benefit of β-adrenergic blockade in patients with mild to moderate heart failure. The recent Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS trial has extended these results to a more advanced patient population. This trial did not, however, include patients who could not reach compensation, patients with far advanced heart failure symptoms, or a significant number of black patients. Future studies of β-blockade may focus on these patients or patients with asymptomatic left ventricular dysfunction.
Generalized Cumulative Residual Entropy for Distributions with Unrestricted Supports
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Noomane Drissi
2008-01-01
Full Text Available We consider the cumulative residual entropy (CRE a recently introduced measure of entropy. While in previous works distributions with positive support are considered, we generalize the definition of CRE to the case of distributions with general support. We show that several interesting properties of the earlier CRE remain valid and supply further properties and insight to problems such as maximum CRE power moment problems. In addition, we show that this generalized CRE can be used as an alternative to differential entropy to derive information-based optimization criteria for system identification purpose.
Lee, Louis P; Limas, Nidia Gabaldon; Cole, Daniel J; Payne, Mike C; Skylaris, Chris-Kriton; Manz, Thomas A
2014-12-01
The density derived electrostatic and chemical (DDEC/c3) method is implemented into the onetep program to compute net atomic charges (NACs), as well as higher-order atomic multipole moments, of molecules, dense solids, nanoclusters, liquids, and biomolecules using linear-scaling density functional theory (DFT) in a distributed memory parallel computing environment. For a >1000 atom model of the oxygenated myoglobin protein, the DDEC/c3 net charge of the adsorbed oxygen molecule is approximately -1e (in agreement with the Weiss model) using a dynamical mean field theory treatment of the iron atom, but much smaller in magnitude when using the generalized gradient approximation. For GaAs semiconducting nanorods, the system dipole moment using the DDEC/c3 NACs is about 5% higher in magnitude than the dipole computed directly from the quantum mechanical electron density distribution, and the DDEC/c3 NACs reproduce the electrostatic potential to within approximately 0.1 V on the nanorod's solvent-accessible surface. As examples of conducting materials, we study (i) a 55-atom Pt cluster with an adsorbed CO molecule and (ii) the dense solids Mo2C and Pd3V. Our results for solid Mo2C and Pd3V confirm the necessity of a constraint enforcing exponentially decaying electron density in the tails of buried atoms.
Cold Matter Assembled Atom-by-Atom
Endres, Manuel; Keesling, Alexander; Levine, Harry; Anschuetz, Eric R; Krajenbrink, Alexandre; Senko, Crystal; Vuletic, Vladan; Greiner, Markus; Lukin, Mikhail D
2016-01-01
The realization of large-scale fully controllable quantum systems is an exciting frontier in modern physical science. We use atom-by-atom assembly to implement a novel platform for the deterministic preparation of regular arrays of individually controlled cold atoms. In our approach, a measurement and feedback procedure eliminates the entropy associated with probabilistic trap occupation and results in defect-free arrays of over 50 atoms in less than 400 ms. The technique is based on fast, real-time control of 100 optical tweezers, which we use to arrange atoms in desired geometric patterns and to maintain these configurations by replacing lost atoms with surplus atoms from a reservoir. This bottom-up approach enables controlled engineering of scalable many-body systems for quantum information processing, quantum simulations, and precision measurements.
Weber, Valéry; Tymczak, Christopher J; Challacombe, Matt
2006-06-14
The application of theoretical methods based on density-functional theory is known to provide atomic and cell parameters in very good agreement with experimental values. Recently, construction of the exact Hartree-Fock exchange gradients with respect to atomic positions and cell parameters within the Gamma-point approximation has been introduced. In this article, the formalism is extended to the evaluation of analytical Gamma-point density-functional atomic and cell gradients. The infinite Coulomb summation is solved with an effective periodic summation of multipole tensors. While the evaluation of Coulomb and exchange-correlation gradients with respect to atomic positions are similar to those in the gas phase limit, the gradients with respect to cell parameters needs to be treated with some care. The derivative of the periodic multipole interaction tensor needs to be carefully handled in both direct and reciprocal space and the exchange-correlation energy derivative leads to a surface term that has its origin in derivatives of the integration limits that depend on the cell. As an illustration, the analytical gradients have been used in conjunction with the QUICCA algorithm to optimize one-dimensional and three-dimensional periodic systems at the density-functional theory and hybrid Hartree-Fock/density-functional theory levels. We also report the full relaxation of forsterite supercells at the B3LYP level of theory.
Determining source cumulants in femtoscopy with Gram-Charlier and Edgeworth series
DEFF Research Database (Denmark)
Eggers, H. C.; De Kock, M. B.; Schmiegel, Jürgen
2011-01-01
Lowest-order cumulants provide important information on the shape of the emission source in femtoscopy. For the simple case of noninteracting identical particles, we show how the fourth-order source cumulant can be determined from measured cumulants in momentum space. The textbook Gram–Charlier s...
High-resolution harmonic retrieval using the full fourth-order cumulant
Vossen, S.H.J.A.; Naus, H.W.L.; Zwamborn, A.P.M.
2010-01-01
The harmonic retrieval (HR) problem concerns the estimation of the frequencies in a sum of real or complex harmonics. Both correlation and cumulant-based approaches are used for this purpose. Cumulant-based HR algorithms use a single 1-D slice of the fourth-order cumulant that is estimated directly
2010-11-15
... AGENCY Workshop: Cumulative Mixtures Risk of Six Selected Phthalates in Support of Summary Information on...: Notice of Peer Consultation Workshop on the Cumulative Mixtures Risk of Six Selected Phthalates; Request... phthalates as set forth in the National Academies of Science (NAS) report ``Phthalates and Cumulative...
Stefańska, Patrycja
2016-01-01
We consider a Dirac one-electron atom placed in a weak, static, uniform magnetic field. We show that, to the first order in the strength B of the external field, the only electric multipole moments, which are induced by the perturbation in the atom, are those of an even order. Using the Sturmian expansion of the generalized Dirac-Coulomb Green function [R. Szmytkowski, J. Phys. B 30, 825 (1997); 30, 2747(E) (1997)], we derive a closed-form expression for the electric quadrupole moment induced in the atom in an arbitrary discrete energy eigenstate. The result, which has the form of a double finite sum involving the generalized hypergeometric functions 3F2 of the unit argument, agrees with the earlier relativistic formula for that quantity, obtained by us for the ground state of the atom.
Stefańska, Patrycja
2016-02-01
We consider a Dirac one-electron atom placed in a weak, static, uniform magnetic field. We show that, to the first order in the strength B of the external field, the only electric multipole moments, which are induced by the perturbation in the atom, are those of an even order. Using the Sturmian expansion of the generalized Dirac-Coulomb Green function [R. Szmytkowski, J. Phys. B 30, 825 (1997), 10.1088/0953-4075/30/4/007; J. Phys. B 30, 2747 (1997), 10.1088/0953-4075/30/11/023], We derive a closed-form expression for the electric quadrupole moment induced in the atom in an arbitrary discrete energy eigenstate. The result, which has the form of a double finite sum involving the generalized hypergeometric functions 3F2 of the unit argument, agrees with the earlier relativistic formula for that quantity, obtained by us for the ground state of the atom.
The seven-year cumulative survival rate of Osstem implants
Kim, Young-Kyun; Kim, Bum-Su; Yun, Pil-Young; Mun, Sang-Un; Yi, Yang-Jin; Jeong, Kyung-In
2014-01-01
Objectives This study was performed to analyze the cumulative survival rate of Osstem implants (Osstem Implant Co., Ltd.) over a seven-year period. Materials and Methods A total of 105 patients who had 467 Osstem implants that were placed at the Section of Dentistry, Seoul National University Bundang Hospital (Seongnam, Korea) from June 2003 through December 2005 were analyzed. The life table method and a cross-tubulation analysis, log rank test were used to evaluate the survival curve and the influence that the prognostic factors. The prognostic factors, i.e., age and gender of patients, diameter and length, type of implants, bone graft history and loading time were determined with a Cox proportional hazard model based on logistic regression analysis. Results The seven-year cumulative survival rate of Osstem implants was 95.37%. The Cox proportional hazard model revealed that the following factors had a significant influence on survival rate; increased diameter, reduced prosthetic loading period and performance of bone grafting. Conclusion The osstem implants showed satisfactory results over the seven-year study period. PMID:24868503
Cumulative human threats on fish biodiversity components in Tunisian waters
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F. BEN RAIS LASRAM
2015-02-01
Full Text Available Human activities are increasingly impacting biodiversity. To improve conservation planning measures in an ecosystem-based management context, we need to explore how the effects of these activities interact with different biodiversity components. In this study, we used a semi-quantitative method to assess the cumulative impacts of human activities on three biodiversity components (species richness, phylogenetic diversity, and functional diversity in Tunisia’s exclusive economic zone. For each of the nine activities considered, we developed an understanding of their effects from local studies and the expert opinion of stakeholders with country-specific experience. We mapped the cumulative effects and the three biodiversity components and then assessed the degree to which these elements overlapped using an overlap index. This is the first time such an assessment has been made for Tunisia’s marine ecosystems and our assessment highlight the inappropriateness of current conservation measures. The results of this study have specific application for the prioritization of future management actions.
Cumulative human threats on fish biodiversity components in Tunisian waters
Directory of Open Access Journals (Sweden)
F. BEN RAIS LASRAM
2014-06-01
Full Text Available Human activities are increasingly impacting biodiversity. To improve conservation planning measures in an ecosystem-based management context, we need to explore how the effects of these activities interact with different biodiversity components. In this study, we used a semi-quantitative method to assess the cumulative impacts of human activities on three biodiversity components (species richness, phylogenetic diversity, and functional diversity in Tunisia’s exclusive economic zone. For each of the nine activities considered, we developed an understanding of their effects from local studies and the expert opinion of stakeholders with country-specific experience. We mapped the cumulative effects and the three biodiversity components and then assessed the degree to which these elements overlapped using an overlap index. This is the first time such an assessment has been made for Tunisia’s marine ecosystems and our assessment highlight the inappropriateness of current conservation measures. The results of this study have specific application for the prioritization of future management actions.
Cumulative dietary exposure of the population of Denmark to pesticides.
Jensen, Bodil Hamborg; Petersen, Annette; Nielsen, Elsa; Christensen, Tue; Poulsen, Mette Erecius; Andersen, Jens Hinge
2015-09-01
We used the Hazard Index (HI) method to carry out a cumulative risk assessment after chronic dietary exposure to all monitored pesticides in fruit, vegetables and cereals for various consumer groups in Denmark. Residue data for all the pesticides were obtained from the Danish monitoring programme during the period 2004-2011. Food consumption data were obtained from DANSDA (the DAnish National Survey of Diet and physical Activity) for the period 2005-2008. The calculations were made using three different models to cope with residues below the limit of reporting (LOR). We concluded that a model that included processing factors and set non-detects to ½ LOR, but limited the correction (Model 3), gave the most realistic exposure estimate. With Model 3 the HI was calculated to be 0.44 for children and 0.18 for adults, indicating that there is no risk of adverse health effects following chronic cumulative exposure to the pesticides found in fruit, vegetables and cereals on the Danish market. The HI was below 1 even for consumers who eat more than 550 g of fruit and vegetables per day, corresponding to 1/3 of the population. Choosing Danish-produced commodities whenever possible could reduce the HI by a factor of 2.
Extraction of Facial Feature Points Using Cumulative Histogram
Paul, Sushil Kumar; Bouakaz, Saida
2012-01-01
This paper proposes a novel adaptive algorithm to extract facial feature points automatically such as eyebrows corners, eyes corners, nostrils, nose tip, and mouth corners in frontal view faces, which is based on cumulative histogram approach by varying different threshold values. At first, the method adopts the Viola-Jones face detector to detect the location of face and also crops the face region in an image. From the concept of the human face structure, the six relevant regions such as right eyebrow, left eyebrow, right eye, left eye, nose, and mouth areas are cropped in a face image. Then the histogram of each cropped relevant region is computed and its cumulative histogram value is employed by varying different threshold values to create a new filtering image in an adaptive way. The connected component of interested area for each relevant filtering image is indicated our respective feature region. A simple linear search algorithm for eyebrows, eyes and mouth filtering images and contour algorithm for nos...
A Cumulant-based Analysis of Nonlinear Magnetospheric Dynamics
Energy Technology Data Exchange (ETDEWEB)
Jay R. Johnson; Simon Wing
2004-01-28
Understanding magnetospheric dynamics and predicting future behavior of the magnetosphere is of great practical interest because it could potentially help to avert catastrophic loss of power and communications. In order to build good predictive models it is necessary to understand the most critical nonlinear dependencies among observed plasma and electromagnetic field variables in the coupled solar wind/magnetosphere system. In this work, we apply a cumulant-based information dynamical measure to characterize the nonlinear dynamics underlying the time evolution of the Dst and Kp geomagnetic indices, given solar wind magnetic field and plasma input. We examine the underlying dynamics of the system, the temporal statistical dependencies, the degree of nonlinearity, and the rate of information loss. We find a significant solar cycle dependence in the underlying dynamics of the system with greater nonlinearity for solar minimum. The cumulant-based approach also has the advantage that it is reliable even in the case of small data sets and therefore it is possible to avoid the assumption of stationarity, which allows for a measure of predictability even when the underlying system dynamics may change character. Evaluations of several leading Kp prediction models indicate that their performances are sub-optimal during active times. We discuss possible improvements of these models based on this nonparametric approach.
Cumulative Effects Assessment: Linking Social, Ecological, and Governance Dimensions
Directory of Open Access Journals (Sweden)
Marian Weber
2012-06-01
Full Text Available Setting social, economic, and ecological objectives is ultimately a process of social choice informed by science. In this special feature we provide a multidisciplinary framework for the use of cumulative effects assessment in land use planning. Forest ecosystems are facing considerable challenges driven by population growth and increasing demands for resources. In a suite of case studies that span the boreal forest of Western Canada to the interior Atlantic forest of Paraguay we show how transparent and defensible methods for scenario analysis can be applied in data-limited regions and how social dimensions of land use change can be incorporated in these methods, particularly in aboriginal communities that have lived in these ecosystems for generations. The case studies explore how scenario analysis can be used to evaluate various land use options and highlight specific challenges with identifying social and ecological responses, determining thresholds and targets for land use, and integrating local and traditional knowledge in land use planning. Given that land use planning is ultimately a value-laden and often politically charged process we also provide some perspective on various collective and expert-based processes for identifying cumulative impacts and thresholds. The need for good science to inform and be informed by culturally appropriate democratic processes calls for well-planned and multifaceted approaches both to achieve an informed understanding of both residents and governments of the interactive and additive changes caused by development, and to design action agendas to influence such change at the ecological and social level.