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1

Solution of generalized shifted linear systems with complex symmetric matrices  

NASA Astrophysics Data System (ADS)

We develop the shifted COCG method [R. Takayama, T. Hoshi, T. Sogabe, S.-L. Zhang, T. Fujiwara, Linear algebraic calculation of Green's function for large-scale electronic structure theory, Phys. Rev. B 73 (165108) (2006) 1-9] and the shifted WQMR method [T. Sogabe, T. Hoshi, S.-L. Zhang, T. Fujiwara, On a weighted quasi-residual minimization strategy of the QMR method for solving complex symmetric shifted linear systems, Electron. Trans. Numer. Anal. 31 (2008) 126-140] for solving generalized shifted linear systems with complex symmetric matrices that arise from the electronic structure theory. The complex symmetric Lanczos process with a suitable bilinear form plays an important role in the development of the methods. The numerical examples indicate that the methods are highly attractive when the inner linear systems can efficiently be solved.

Sogabe, Tomohiro; Hoshi, Takeo; Zhang, Shao-Liang; Fujiwara, Takeo

2012-07-01

2

Complex geometric optics for symmetric hyperbolic systems I: linear theory  

E-print Network

We obtain an asymptotic solution for $\\ep \\to 0$ of the Cauchy problem for linear first-order symmetric hyperbolic systems with oscillatory initial values written in the eikonal form of geometric optics with frequency $1/\\ep$, but with complex phases. For the most common linear wave propagation models, this kind on Cauchy problems are well-known in the applied literature and their asymptotic theory, referred to as complex geometric optics, is attracting interest for applications. In this work, which is the first of a series of papers dedicated to complex geometric optics for nonlinear symmetric hyperbolic systems, we develop a rigorous linear theory and set the basis for the subsequent nonlinear analysis.

Omar Maj

2008-02-12

3

Existence and uniqueness for spherically symmetric linear transport  

Microsoft Academic Search

The purpose of this note is to establish an existence and uniqueness theorem for the spherically and azimuthally symmetric steady-state linear transport equation. The methods used are similar to those of Olhoeft for bounded three-dimensional geometry and of Nelson for linear transport in a slab. Our basic result contains the corollary that, for very general scattering laws, nonmultiplying transport of

Paul Nelson; John M. Paulling

1982-01-01

4

Linear relaxation processes governed by fractional symmetric kinetic equations  

Microsoft Academic Search

The fractional symmetric Fokker-Planck and Einstein-Smoluchowski kinetic equations that describe the evolution of systems\\u000a influenced by stochastic forces distributed with stable probability laws are derived. These equations generalize the known\\u000a kinetic equations of the Brownian motion theory and involve symmetric fractional derivatives with respect to velocity and\\u000a space variables. With the help of these equations, the linear relaxation processes in

A. V. Chechkin; V. Yu. Gonchar

2000-01-01

5

Invisibility in PT-symmetric complex crystals  

E-print Network

Bragg scattering in sinusoidal PT-symmetric complex crystals of finite thickness is theoretically investigated by the derivation of exact analytical expressions for reflection and transmission coefficients in terms of modified Bessel functions of first kind. The analytical results indicate that unidirectional invisibility, recently predicted for such crystals by coupled-mode theory [Z. Lin et al., Phys. Rev. Lett. 106, 213901 (2011)], breaks down for crystals containing a large number of unit cells. In particular, for a given modulation depth in a shallow sinusoidal potential, three regimes are encountered as the crystal thickness is increased. At short lengths the crystal is reflectionless and invisible when probed from one side (unidirectional invisibility), whereas at intermediate lengths the crystal remains reflectionless but not invisible; for longer crystals both unidirectional reflectionless and invisibility properties are broken.

Stefano Longhi

2011-11-15

6

Scattering of linear and nonlinear waves in a waveguide array with a PT-symmetric defect  

SciTech Connect

We study the scattering of linear and nonlinear waves in a long waveguide array with a parity-time (PT)-symmetric defect created by two waveguides with balanced gain and loss. We present exact solutions for the scattering of linear waves on such a defect, and then demonstrate numerically that the linear theory can describe, with a good accuracy, the soliton scattering in the case of weak nonlinearity. We reveal that the reflected and transmitted linear and nonlinear waves can be amplified substantially after interaction with the PT-symmetric defect thus allowing an active control of the wave scattering in the array.

Dmitriev, Sergey V.; Suchkov, Sergey V. [Institute for Metals Superplasticity Problems, Russian Academy of Science, Ufa RU-450001 (Russian Federation); Sukhorukov, Andrey A.; Kivshar, Yuri S. [Nonlinear Physics Centre, Research School of Physics and Engineering,Australian National University, Canberra, ACT 0200 (Australia)

2011-07-15

7

Transparency of PT-symmetric complex potentials for coherent injection  

E-print Network

It is known that when two identical waves are injected from left and right on a complex PT-symmetric scattering potential the two-port s-matrix can have uni-modular eigenvalues. If this happens for all energies, there occurs a perfect emission of waves at both ends. We call this phenomenon transparency. Using the versatile PT-Symmetric complex Scarf II potential, we demonstrate analytically that the transparency occurs when the potential has real discrete spectrum i.e., when PT-symmetry is exact(unbroken). Next, we find that exactness of PT-symmetry is only sufficient but not necessary for the transparency. Two other PT-symmetric domains of Scarf II reveal transparency without the PT-symmetry being exact. In these two cases there exist only scattering states. In one case the real part of the potential is a well devoid of real discrete spectrum and in the other real part is a barrier. Other numerically solved models also support our findings.

Zafar Ahmed; Joseph Amal Nathan

2014-10-21

8

Algorithm 937: MINRES-QLP for Symmetric and Hermitian Linear Equations and Least-Squares Problems  

PubMed Central

We describe algorithm MINRES-QLP and its FORTRAN 90 implementation for solving symmetric or Hermitian linear systems or least-squares problems. If the system is singular, MINRES-QLP computes the unique minimum-length solution (also known as the pseudoinverse solution), which generally eludes MINRES. In all cases, it overcomes a potential instability in the original MINRES algorithm. A positive-definite pre-conditioner may be supplied. Our FORTRAN 90 implementation illustrates a design pattern that allows users to make problem data known to the solver but hidden and secure from other program units. In particular, we circumvent the need for reverse communication. Example test programs input and solve real or complex problems specified in Matrix Market format. While we focus here on a FORTRAN 90 implementation, we also provide and maintain MATLAB versions of MINRES and MINRES-QLP. PMID:25328255

Choi, Sou-Cheng T.; Saunders, Michael A.

2014-01-01

9

A multilevel iterative method for symmetric, positive definite linear complementarity problems  

Microsoft Academic Search

A fast iterative method for the solution of large, sparse, symmetric, positive definite linear complementarity problems is presented. The iterations reduce to linear iterations in a neighborhood of the solution if the problem is nondegenerate. The variational setting of the method guarantees global convergence.

Jan Mandel

1984-01-01

10

On the linear stability of the extreme Kerr black hole under axially symmetric perturbations  

NASA Astrophysics Data System (ADS)

We prove that for axially symmetric linear gravitational perturbations of the extreme Kerr black hole, there exists a positive definite and conserved energy. This provides a basic criteria for linear stability in axial symmetry. In the particular case of Minkowski, using this energy we also prove the pointwise boundedness of the perturbation in a remarkably simple way.

Dain, Sergio; Gentile de Austria, Ivan

2014-10-01

11

Talbot self-imaging in PT-symmetric complex crystals  

NASA Astrophysics Data System (ADS)

The Talbot effect, i.e., the self-imaging property of a periodic wave in near-field diffraction, is a remarkable interference phenomenon in paraxial systems with continuous translational invariance. In crystals, i.e., systems with discrete translational invariance, self-imaging has been regarded so far as a rare effect, restricted to special sets of initial field distributions. Here it is shown that in a class of gapless PT-symmetric complex crystals at the symmetry-breaking threshold Talbot revivals can arise for almost any initial periodic wave distribution which is commensurate with the lattice period. A possible experimental realization of commensurate Talbot self-imaging for light pulses in complex "temporal" crystals, realized in an optical dispersive fiber loop with amplitude and phase modulators, is briefly discussed.

Longhi, Stefano

2014-10-01

12

Performance Bounds for Nonbinary Linear Block Codes Over Memoryless Symmetric Channels  

Microsoft Academic Search

The performance of nonbinary linear block codes is studied in this paper via the derivation of new upper bounds on the block error probability under maximum-likelihood (ML) decoding. The transmission of these codes is assumed to take place over a memoryless and symmetric channel. The new bounds, which are based on the Gallager bounds and their variations, are applied to

Eran Hof; Igal Sason; Shlomo Shamai

2009-01-01

13

Contrasting photophysical properties of star-shaped vs linear perylene diimide complexes.  

PubMed

The absorption line shapes of a series of linear and star-shaped perylene diimide (PDI) complexes are evaluated theoretically and compared to experiment. The cyclic trimer and tetrahedral complexes are part of the symmetric series, characterized by a single interchromophoric coupling, J(0), between any two PDI chromophores. The measured spectra of all complexes show pronounced vibronic progressions based on the symmetric ring stretching mode at ~1400 cm(-1). The spectral line shapes are accurately reproduced using a Holstein Hamiltonian parametrized with electronic couplings calculated using time-dependent density functional transition charge densities. Although the "head-to-tail" linear complexes display classic J-aggregate behavior, the star-shaped complexes display a unique photophysical response, which is neither J- nor H-like. In the symmetric N-mers (N = 2-4), absorption and emission are polarized along N - 1 directions in contrast to linear complexes where absorption and emission remain polarized along the long molecular axis. In the symmetric complexes the red-shift of the 0-0 peak with increasing |J(0)|, as well as the initial linear rise of the 0-0/1-0 oscillator strength ratio with increasing |J(0)|, are independent of the number of PDI chromophores, N, and are markedly smaller than what is found in the linear series, where the shifts and ratios depend on N. Moreover, whereas the radiative decay rate, ?(r), scales with N and is therefore superradiant in linear complexes, ?(r) scales with N/(N - 1) in the symmetric complexes. Vibronic/vibrational pair states (two-particle states) are found to profoundly affect the absorption line shapes of both linear and symmetric complexes for sufficiently large coupling. PMID:23402395

Pochas, Christopher M; Kistler, Kurt A; Yamagata, Hajime; Matsika, Spiridoula; Spano, Frank C

2013-02-27

14

Spherically symmetric analysis on open FLRW solution in non-linear massive gravity  

NASA Astrophysics Data System (ADS)

We study non-linear massive gravity in the spherically symmetric context. Our main motivation is to investigate the effect of helicity-0 mode which remains elusive after analysis of cosmological perturbation around an open Friedmann-Lemaitre-Robertson-Walker (FLRW) universe. The non-linear form of the effective energy-momentum tensor stemming from the mass term is derived for the spherically symmetric case. Only in the special case where the area of the two sphere is not deviated away from the FLRW universe, the effective energy momentum tensor becomes completely the same as that of cosmological constant. This opens a window for discriminating the non-linear massive gravity from general relativity (GR). Indeed, by further solving these spherically symmetric gravitational equations of motion in vacuum to the linear order, we obtain a solution which has an arbitrary time-dependent parameter. In GR, this parameter is a constant and corresponds to the mass of a star. Our result means that Birkhoff's theorem no longer holds in the non-linear massive gravity and suggests that energy can probably be emitted superluminously (with infinite speed) on the self-accelerating background by the helicity-0 mode, which could be a potential plague of this theory.

Chiang, Chien-I.; Izumi, Keisuke; Chen, Pisin

2012-12-01

15

Spherically symmetric analysis on open FLRW solution in non-linear massive gravity  

E-print Network

We study non-linear massive gravity in the spherically symmetric context. Our main motivation is to investigate the effect of helicity-0 mode which remains elusive after analysis of cosmological perturbation around an open Friedmann-Lemaitre-Robertson-Walker (FLRW) universe. The non-linear form of the effective energy-momentum tensor stemming from the mass term is derived for the spherically symmetric case. Only in the special case where the area of the two sphere is not deviated away from the FLRW universe, the effective energy momentum tensor becomes completely the same as that of cosmological constant. This opens a window for discriminating the non-linear massive gravity from general relativity (GR). Indeed, by further solving these spherically symmetric gravitational equations of motion in vacuum to the linear order, we obtain a solution which has an arbitrary time-dependent parameter. In GR, this parameter is a constant and corresponds to the mass of a star. Our result means that Birkhoff's theorem no longer holds in the non-linear massive gravity and suggests that energy can probably be emitted superluminously (with infinite speed) on the self-accelerating background by the helicity-0 mode, which could be a potential plague of this theory.

Chien-I Chiang; Keisuke Izumi; Pisin Chen

2012-08-06

16

Gallager-type bounds for non-binary linear block codes over memoryless symmetric channels  

Microsoft Academic Search

The performance analysis of non-binary linear block codes is studied under ML decoding where it is assumed that the transmission takes place over memoryless symmetric channels. Gallager-type bounds are derived, and the proposed bounds are exemplified for expurgated regular ensembles of non-binary low-density parity-check (LDPC) codes. These bounds are also compared with classical and recent improved sphere-packing bounds, indicating that

Eran Hof; Igal Sason; Shlomo Shamai

2008-01-01

17

Scattering of solitons by complex symmetric gaussian potentials.  

PubMed

Scattering of bright soliton by -symmetric potential well and barrier is investigated numerically. The numerical results show that increasing strength of real part of -symmetric potential can cause repeated reflection, transmission, and trapping regions due to energy exchange between the kinetic energy of incoming soliton and the internal modes of the potential structure. In addition, the width of the scattering windows increases with increase of the imaginary part of the -symmetric potential. The results obtained can be exploited in the development of interferometry as well as for diodes devices in information technology. PMID:25321582

Al-Marzoug, S M

2014-09-01

18

A COMBINATORIAL CONJECTURE RELATED WITH COMPLEX BOUNDED SYMMETRIC DOMAINS  

E-print Network

GUY ROOS 1. Motivations Let be a bounded irreducible symmetric: ____________ Date: 7th November 2004. 1 #12; 2 GUY. As the function FO,~ is related to the Bergman kernel of a family of bounded (non homogeneous) domains

19

Dynamics of Symmetric Conserved Mass Aggregation Model on Complex Networks  

Microsoft Academic Search

We investigate the dynamical behaviour of the aggregation process in the symmetric conserved mass aggregation model under three different topological structures. The dispersion sigma(t, L) = (sigmai(mi - rho0)2\\/L)½ is defined to describe the dynamical behaviour where rhoo is the density of particle and mi is the particle number on a site. It is found numerically that for a regular

Da-Yin Hua

2009-01-01

20

Future global non-linear stability of surface symmetric solutions of the Einstein-Vlasov system with a cosmological constant  

E-print Network

We show future global non-linear stability of surface symmetric solutions of the Einstein-Vlasov system with a positive cosmological constant. Estimates of higher derivatives of the metric and the matter terms are obtained using an inductive argument. In a recent research monograph Ringstr\\"{o}m shows future non-linear stability of (not necessarily symmetric) solutions of the Einstein-Vlasov system with a non-linear scalar field if certain local estimates on the geometry and the matter terms are fulfilled. We show that these assumptions are satisfied at late times for the case under consideration here which together with Cauchy stability leads to our main conclusion.

Ernesto Nungesser

2014-02-27

21

The complexity of propositional linear temporal logics  

Microsoft Academic Search

We consider the complexity of satisfiability and determination of truth in a particular finite structure for different propositional linear temporal logics. We show that both the above problems are NP-complete for the logic with F operator and are PSPACE-complete for the logics with F,X, with U, with U,S,X, and Wolper's extended logic with regular operators [Wo81].

A. Prasad Sistla; Edmund M. Clarke

1982-01-01

22

High-pulse-energy, linear optical parametric oscillator with narrow and symmetrical far field.  

PubMed

A new method to obtain a narrow and symmetrical far field from a high-pulse-energy optical parametric oscillator (OPO) with a linear resonator has been tested. The OPO employs two identical nonlinear crystals that are cut for type II phase matching, rotated such that their walk-off planes are orthogonal, and separated by a broadband half-wave plate. The OPO has a simple geometry, can be double-pass pumped, is wavelength tunable and operates stably with high conversion efficiency. The method has been demonstrated in a KTP-based OPO pumped at 1064 nm and a BBO-based OPO pumped at 532 nm, with output pulse energies up to 60 mJ and 75 mJ, respectively. PMID:24105562

Farsund, Øystein; Rustad, Gunnar

2013-08-26

23

A shared minimum-error discrimination among three linearly dependent mirror-symmetric qubit states  

NASA Astrophysics Data System (ADS)

We discuss how a shared minimum-error discrimination (SMD) may be implemented by two remote partners Alice and Bob. Here Bob is given a qubit prepared in one of three linearly dependent mirror-symmetric states with a priori probability. Alice has the knowledge of Bob's signal states, but Bob has not. We show that the shared generalized measurement could be realized by Alice performing a suitable unitary evolution from acting on her system to acting on Bob's system, and remotely rotating the optimal measurement directions to coincide with Bob's basis vectors. In this case, Bob could perform a local orthogonal measurement to determine his signal states with the smallest possible error and without inconclusive answers. A quantum network, which is realizable with current technology, is suggested to implement this SMD.

Chen, Libing; Lu, Hong

2013-08-01

24

The Real Anatomy of Complex Linear Superfields  

E-print Network

Recent work on classicication of off-shell representations of N-extended worldline supersymmetry without central charges has uncovered an unexpectedly vast number--trillions of even just (chromo)topology types--of so called adinkraic supermultiplets. Herein, we show by explicit analysis that a long-known but rarely used representation, the complex linear supermultiplet, is not adinkraic, cannot be decomposed locally, but may be reduced by means of a Wess-Zumino type gauge. This then indicates that the already unexpectedly vast number of adinkraic off-shell supersymmetry representations is but the proverbial tip of the iceberg.

S. J. Gates Jr; J. Hallett; T. Hubsch; K. Stiffler

2012-02-20

25

The Real Anatomy of Complex Linear Superfields  

E-print Network

Recent work on classicication of off-shell representations of N-extended worldline supersymmetry without central charges has uncovered an unexpectedly vast number--trillions of even just (chromo)topology types--of so called adinkraic supermultiplets. Herein, we show by explicit analysis that a long-known but rarely used representation, the complex linear supermultiplet, is not adinkraic, cannot be decomposed locally, but may be reduced by means of a Wess-Zumino type gauge. This then indicates that the already unexpectedly vast number of adinkraic off-shell supersymmetry representations is but the proverbial tip of the iceberg.

Gates, S J; Hubsch, T; Stiffler, K

2012-01-01

26

Response of Seismometer with Symmetric Triaxial Sensor Configuration to Complex Ground Motion  

NASA Astrophysics Data System (ADS)

Most instruments used in seismological practice to record ground motion in all directions use three sensors oriented toward North, East and upward. In this standard configuration horizontal and vertical sensors differ in their construction because of gravity acceleration always applied to a vertical sensor. An alternative way of symmetric sensor configuration was first introduced by Galperin (1955) for petroleum exploration. In this arrangement three identical sensors are also positioned orthogonally to each other but are tilted at the same angle of 54.7 degrees to the vertical axis (triaxial system of coordinate balanced on its corner). Records obtained using symmetric configuration must be rotated into an earth referenced X, Y, Z coordinate system. A number of recent seismological instruments (e.g., broadband seismometers Streckeisen STS-2, Trillium of Nanometrics and Cronos of Kinemetrics) are using symmetric sensor configuration. In most of seismological studies it is assumed that rotational (rocking and torsion) components of earthquake ground motion are small enough to be neglected. However, recently examples were shown when rotational components are significant relative to translational components of motions. Response of pendulums installed in standard configuration (vertical and two horizontals) to complex input motion that includes rotations has been studied in a number of publications. We consider the response of pendulums in a symmetric sensor configuration to complex input motions including rotations, and the resultant triaxial system response. Possible implications of using symmetric sensor configuration in strong motion studies are discussed. Considering benefits of equal design of all three sensors in symmetric configuration, and as a result potentially lower cost of the three-component accelerograph, it may be useful for strong motion measurements not requiring high resolution post signal processing. The disadvantage of this configuration is that if one of the sensors is not working properly or there is a misalignment of sensors, it results in degradation of all three components. Symmetric sensor configuration requires identical processing of each channel putting a number of limitations on further processing of strong motion records.

Graizer, V.

2007-12-01

27

Linear stability of spherically symmetric and wormhole solutions supported by the sine-Gordon ghost scalar field  

SciTech Connect

In this paper we investigate wormhole and spherically symmetric solutions in four-dimensional gravity plus a matter source consisting of a ghost scalar field with a sine-Gordon potential. For the wormhole solutions we also include the possibility of electric and/or magnetic charges. For both types of solutions we perform a linear stability analysis and show that the wormhole solutions are stable and that when one turns on the electric and/or magnetic field the solution remains stable. The linear stability analysis of the spherically symmetric solutions indicates that they can be stable or unstable depending on one of the parameters of the system. This result for the spherically symmetric solution is nontrivial since a previous investigation of four-dimensional gravity plus a ghost scalar field with a {lambda}{phi}{sup 4} interaction found only unstable spherically symmetric solutions. Both the wormhole and spherically symmetric solutions presented here asymptotically go to anti-de Sitter space-time.

Dzhunushaliev, Vladimir [Institute for Basic Research, Eurasian National University, Astana, 010008 (Kazakhstan); Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, 265 a, Chui Street, Bishkek, 720071 (Kyrgyzstan); Institut fuer Physik, Universitaet Oldenburg, Postfach 2503 D-26111 Oldenburg (Germany); Folomeev, Vladimir [Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, 265 a, Chui Street, Bishkek, 720071 (Kyrgyzstan); Institut fuer Physik, Universitaet Oldenburg, Postfach 2503 D-26111 Oldenburg (Germany); Singleton, Douglas [Physics Department, CSU Fresno, Fresno, California 93740-8031 (United States); Myrzakulov, Ratbay [Eurasian International Center for Theoretical Physics and Department of General and Theoretical Physics, Eurasian National University, Astana, 010008 (Kazakhstan)

2010-08-15

28

Geometry-based Computation of Symmetric Homo-oligomeric Protein Complexes  

Microsoft Academic Search

The need to engineer novel therapeutics and functional materials is driving the in-silico design of molecular complexes. This paper proposes a method to compute symmetric homo-oligomeric protein complexes when the structure of the replicated protein monomer is known and rigid. The relationship between the structure of a protein and its biological function brings the in-silico determina- tion of protein structures

Christopher Miles; Brian Olson; Amarda Shehu

29

Symmetrical modified dual tree complex wavelet transform for processing quadrature Doppler ultrasound signals.  

PubMed

Dual-tree complex wavelet transform (DTCWT), which is a shift invariant transform with limited redundancy, is an improved version of discrete wavelet transform. Complex quadrature signals are dual channel signals obtained from the systems employing quadrature demodulation. An example of such signals is quadrature Doppler signal obtained from blood flow analysis systems. Prior to processing Doppler signals using the DTCWT, directional flow signals must be obtained and then two separate DTCWT applied, increasing the computational complexity. In this study, in order to decrease computational complexity, a symmetrical modified DTCWT algorithm is proposed (SMDTCWT). A comparison between the new transform and the symmetrical phasing-filter technique is presented. Additionally denoising performance of SMDTCWT is compared with the DWT and the DTCWT using simulated signals. The results show that the proposed method gives the same output as the symmetrical phasing-filter method, the computational complexity for processing quadrature signals using DTCWT is greatly reduced and finally the SMDTCWT based denoising outperforms conventional DWT with same computational complexity. PMID:22255416

Serbes, G; Aydin, N

2011-01-01

30

Analysis of the static properties of cluster formations in symmetric linear multiblock This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Analysis of the static properties of cluster formations in symmetric linear multiblock copolymers This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2011 J. Phys properties of cluster formations in symmetric linear multiblock copolymers N G Fytas1 and P E Theodorakis2

Theodorakis, Panagiotis E.

31

Symmetrized complex amplitudes for He double photoionization from the time-dependent close coupling and exterior complex scaling methods  

SciTech Connect

Symmetrized complex amplitudes for the double photoionization of helium are computed by the time-dependent close-coupling and exterior complex scaling methods, and it is demonstrated that both methods are capable of the direct calculation of these amplitudes. The results are found to be in excellent agreement with each other and in very good agreement with results of other ab initio methods and experiment.

Horner, D.A.; Colgan, J.; Martin, F.; McCurdy, C.W.; Pindzola, M.S.; Rescigno, T.N.

2004-06-01

32

A Family of Symmetric Linear Multistep Methods for the Numerical Solution of the Schroedinger Equation and Related Problems  

SciTech Connect

We develop a new family of explicit symmetric linear multistep methods for the efficient numerical solution of the Schroedinger equation and related problems with oscillatory solution. The new methods are trigonometrically fitted and have improved intervals of periodicity as compared to the corresponding classical method with constant coefficients and other methods from the literature. We also apply the methods along with other known methods to real periodic problems, in order to measure their efficiency.

Anastassi, Z. A. [Department of Finance and Auditing, School of Management and Economics, Technological Educational Institute of Kalamata, GR-241 00 Antikalamos (Greece); Simos, T. E. [Laboratory of Computational Sciences, Department of Computer Science and Technology, Faculty of Sciences and Technology, University of Peloponnese, GR-22 100 Tripolis (Greece)

2010-09-30

33

Complex geometric optics for symmetric hyperbolic systems II: nonlinear theory in one space dimension  

E-print Network

This is the second part of a work aimed to study complex-phase oscillatory solutions of nonlinear symmetric hyperbolic systems. We consider, in particular, the case of one space dimension. That is a remarkable case, since one can always satisfy the \\emph{naive} coherence condition on the complex phases, which is required in the construction of the approximate solution. Formally the theory applies also in several space dimensions, but the \\emph{naive} coherence condition appears to be too restrictive; the identification of the optimal coherence condition is still an open problem.

Omar Maj

2008-02-12

34

Symmetrization in the geometric theory of functions of a complex variable  

NASA Astrophysics Data System (ADS)

CONTENTSIntroduction Chapter I. Symmetrization transformations §1. Capacities 1. Functions satisfying the Lipschitz condition 2. Condenser capacity 3. Reduced modulus and inner radius §2. Polarization §3. Symmetrization 1. Schwarz symmetrization 2. Steiner symmetrization 3. Circular symmetrization 4. Symmetrization of functions 5. Elliptic symmetrization 6. Symmetrization with respect to a circle §4. Piecewise separating symmetrization 1. Separating transformation 2. Other types of piecewise separating symmetrization §5. Averaging transformations §6. Dissymmetrization Comments on Chapter I Chapter II. Application of symmetrization transformations to some problems in geometric function theory §7. Inequalities for moduli and capacities 1. Annuli 2. The Fekete problem3. Subsets of the unit circle4. Gonchar's problem5. Polygons §8. Estimates of harmonic measure §9. Problems of extremal partitioning1. Fixed poles2. Free poles §10. Univalent functions 1. The Szegö problem 2. The Bazilevich problem 3. Distortion theorems 4. Covering theorems §11. Multivalent functions 1. Symmetrization of plane images 2. Symmetrization of a Riemann surface Unsolved problems References

Dubinin, V. N.

1994-02-01

35

A Symmetrical Tetramer for S. aureus Pyruvate Carboxylase in Complex with Coenzyme A  

SciTech Connect

Pyruvate carboxylase (PC) is a conserved metabolic enzyme with important cellular functions. We report crystallographic and cryo-electron microscopy (EM) studies of Staphylococcus aureus PC (SaPC) in complex with acetyl-CoA, an allosteric activator, and mutagenesis, biochemical, and structural studies of the biotin binding site of its carboxyltransferase (CT) domain. The disease-causing A610T mutation abolishes catalytic activity by blocking biotin binding to the CT active site, and Thr908 might play a catalytic role in the CT reaction. The crystal structure of SaPC in complex with CoA reveals a symmetrical tetramer, with one CoA molecule bound to each monomer, and cryo-EM studies confirm the symmetrical nature of the tetramer. These observations are in sharp contrast to the highly asymmetrical tetramer of Rhizobium etli PC in complex with ethyl-CoA. Our structural information suggests that acetyl-CoA promotes a conformation for the dimer of the biotin carboxylase domain of PC that might be catalytically more competent.

Yu, L.; Xiang, S; Lasso, G; Gil, D; Valle, M; Tong, L

2009-01-01

36

Talbot self-imaging in $\\mathcal{PT}$-symmetric complex crystals  

E-print Network

The Talbot effect, i.e. the self-imaging property of a periodic wave in near-field diffraction, is a remarkable interference phenomenon in paraxial systems with continuous translational invariance. In crystals, i.e. systems with discrete translational invariance, self-imaging has been regarded so far as a seldom effect, restricted to special sets of initial field distributions. Here it is shown that in a class of gapless $\\mathcal{PT}$-symmetric complex crystals at the symmetry breaking threshold Talbot revivals can arise for almost any initial periodic wave distribution which is commensurate with the lattice period. A possible experimental realization of commensurate Talbot self-imaging for light pulses in complex 'temporal' crystals, realized in an optical dispersive fiber loop with amplitude and phase modulators, is briefly discussed.

Longhi, Stefano

2014-01-01

37

WORKSHEET ON REAL AND COMPLEX LINEAR MAPS CHARLES REZK  

E-print Network

WORKSHEET ON REAL AND COMPLEX LINEAR MAPS CHARLES REZK These problems are about the relationship. This means that if V and W are vector spaces over C, we speak of a map f : V W being C-linear or R-linear. Date: October 31, 2011. 1 #12;2 CHARLES REZK (7) Show that Conj: CnÃ?1 CnÃ?1 is a C

Rezk, Charles

38

Low complexity iterative receiver for linear precoded MIMO systems  

E-print Network

Low complexity iterative receiver for linear precoded MIMO systems Pierre-Jean Bouvet, Maryline Email: pierrejean.bouvet@rd.francetelecom.com Abstract-- In a Multiple Input Multiple Output (MIMO of the space-time detector which consists of an MMSE MIMO PSIC equalizer and a linear deprecoder. Spectral

Paris-Sud XI, Université de

39

WORKSHEET ON REAL AND COMPLEX LINEAR MAPS CHARLES REZK  

E-print Network

WORKSHEET ON REAL AND COMPLEX LINEAR MAPS CHARLES REZK These problems are about the relationship. This means that if V and W are vector spaces over C, we speak of a map f : V W being C-linear or R a suitable choice of eigenvectors and eigenvalues.) Date: April 21, 2012. 1 #12;2 CHARLES REZK Recall

Rezk, Charles

40

Computational Complexity and Numerical Stability of Linear Problems  

Microsoft Academic Search

We survey classical and recent developments in numerical linear algebra, focusing on two issues: computational complexity, or arithmetic costs, and numerical stability, or perfor- mance under roundo error. We present a brief account of the algebraic complexity theory as well as the general error analysis for matrix multiplication and related problems. We em- phasize the central role played by the

Olga Holtz; Noam Shomron

2009-01-01

41

Infinitely many solutions to linearly coupled Schrödinger equations with non-symmetric potential  

E-print Network

We study the following linearly coupled Schr\\"{o}dinger equations in $\\R^N(N\\leq3),$ $$\\left\\{% \\begin{array}{ll} -\\Delta u+(1+\\epsilon P(x))u=u^3+\\beta v, & \\hbox{$x\\in \\R^N$}, \\vspace{0.2cm} -\\Delta v+(1+\\epsilon Q(x))v=v^3+\\beta u, & \\hbox{$x\\in\\R^N$}, \\end{array}% \\right.$$ where the potentials $P(x),Q(x)$ are continuous functions satisfying suitable decay assumptions, but without any symmetry properties, $\\epsilon$ is a positive constant, $\\beta\\in \\R$ is a coupling constant. Using the Liapunov-Schmidt reduction methods two times and localized energy method, we prove that the above problem has infinitely many positive synchronized solutions, which extends the result Theorem 1.2 about nonlinearly coupled Schr\\"{o}dinger equations in \\cite{aw} to our linearly coupled problem.

Chunhua Wang; Jing Yang

2014-03-10

42

Malachite green mediates homodimerization of antibody VL domains to form a fluorescent ternary complex with singular symmetric interfaces  

PubMed Central

We report that a symmetric small molecule ligand mediates the assembly of antibody light chain variable domains (VLs) into a correspondent symmetric ternary complex with novel interfaces. The L5* Fluorogen Activating Protein (FAP) is a VL domain that binds malachite green dye (MG) to activate intense fluorescence. Crystallography of liganded L5* reveals a 2:1 protein:ligand complex with inclusive C2 symmetry, where MG is almost entirely encapsulated between an antiparallel arrangement of the two VL domains. Unliganded L5* VL domains crystallize as a similar antiparallel VL/VL homodimer. The complementarity determining regions (CDRs) are spatially oriented to form novel VL/VL and VL/ligand interfaces that tightly constrain a propeller conformer of MG. Binding equilibrium analysis suggests highly cooperative assembly to form a very stable VL/MG/VL complex, such that MG behaves as a strong chemical inducer of dimerization. Fusion of two VL domains into a single protein tightens MG binding over 1,000-fold to low picomolar affinity without altering the large binding enthalpy, suggesting that bonding interactions with ligand and restriction of domain movements make independent contributions to binding. Fluorescence activation of a symmetrical fluorogen provides a selection mechanism for the isolation and directed evolution of ternary complexes where unnatural symmetric binding interfaces are favored over canonical antibody interfaces. As exemplified by L5*, these self-reporting complexes may be useful as modulators of protein association or as high affinity protein tags and capture reagents. PMID:23978698

Szent-Gyorgyi, Chris; Stanfield, Robyn L.; Andreko, Susan; Dempsey, Alison; Ahmed, Mushtaq; Capek, Sara; Waggoner, Alan; Wilson, Ian A.; Bruchez, Marcel P.

2013-01-01

43

Parity-time (PT) symmetric Double-lambda optical quadrimer waveguides in linear and nonlinear regimes  

E-print Network

We report a study on an optical quadrimer waveguides (WGs) system spatially arranged in the form of double-lambda structure, a configuration reminiscent of atomic physics and quantum optics. We have studied the beam dynamics of the system below, at and above the PT-threshold in both the linear and nonlinear regimes. We have also explored the effects of gain/loss parameter and the strength as well as the nature of the nonlinearity (i.e. focusing or defocusing) upon the evolution of optical intensity in each of the four sites. We observe saturation behaviors in the spatial power evolution, when nonlinearity is incorporated into the system, in the gain-guides, a feature that could be exploited for various practical applications.

Gupta, Samit Kumar; Sarma, Amarendra K

2014-01-01

44

Solving complex-valued linear systems via equivalent real formulations  

SciTech Connect

Most algorithms used in preconditioned iterative methods are generally applicable to complex valued linear systems, with real valued linear systems simply being a special case. However, most iterative solver packages available today focus exclusively on real valued systems, or deal with complex valued systems as an afterthought. One obvious approach to addressing this problem is to recast the complex problem into one of a several equivalent real forms and then use a real valued solver to solve the related system. However, well-known theoretical results showing unfavorable spectral properties for the equivalent real forms have diminished enthusiasm for this approach. At the same time, experience has shown that there are situations where using an equivalent real form can be very effective. In this paper, the authors explore this approach, giving both theoretical and experimental evidence that an equivalent real form can be useful for a number of practical situations. Furthermore, they show that by making good use of some of the advance features of modem solver packages, they can easily generate equivalent real form preconditioners that are computationally efficient and mathematically identical to their complex counterparts. Using their techniques, they are able to solve very ill-conditioned complex valued linear systems for a variety of large scale applications. However, more importantly, they shed more light on the effectiveness of equivalent real forms and more clearly delineate how and when they should be used.

DAY,DAVID M.; HEROUX,MICHAEL A.

2000-05-22

45

Charge-transfer complexes of some linear conjugated polyenes.  

PubMed Central

On adsorption of some electron-acceptor molecules on the solid films of all-trans-beta-carotene, beta-apo-8'-carotenal, astacene and methylbixin a new absorption band appears on the longer-wavelength side of the spectrum in addition to the original bands. The position of this new band is dependent on the electron affinity (EA) of the acceptor molecules, and the intensity of this band increases with the amount of adsorbed acceptor molecules. A linear relationship between the vmax. of the new band and EA was observed. The value of the ionization potential of the polyenes estimated from such linear relationship agrees satisfactorily with the value obtained by other methods. It has been concluded that the polyenes behave as electron donor and first form molecular charge-transfer complexes (of type [polyene . I2] with iodine) with electron acceptors, these finally dissociating to yield ionic complexes (of type [polyene . I+] with iodine). PMID:7213346

Mallik, B; Jain, K M; Misra, T N

1980-01-01

46

Modified linear polyethylenimine-cholesterol conjugates for DNA complexation.  

PubMed

Linear polyethylenimine (LPEI) is an effective nonviral gene carrier with transfection levels equal or above branched polyethylenimine (BPEI) and exhibits a lower cytotoxicity profile than BPEI. High molecular weight LPEI M(w) 25 k was modified with cholesterol in three different geometries: linear shaped (L), T-shaped (T), and a combined linear/T-shaped (LT) forming the LPEI-cholesterol (LPC) conjugates LPC-L, LPC-T, and LPC-LT, respectively. Physical characterization of LPC/pDNA complexes included particle size, zeta potential, DNase protection, mIL-12 p70 expression, and cytotoxicity. The particle size was further confirmed by atomic force microscopy (AFM). The LPC-T/pDNA complexes were optimal at N/P 10/1 that resulted in a particle size of approximately 250 nm, which was confirmed by AFM, and a surface charge of +10 mV. These complexes also effectively protected the pDNA for up to 180 min in the presence of DNase I. B16-F0 cells transfected with LPC-L and LPC-T showed protein expression levels higher than LPEI alone and twice that of BPEI but without any significant loss in cell viability. These results were confirmed with EGFP flow cytometry and transfection of Renca cells. The differences in rates of transfection of the LPC/pDNA complexes is due in part to conformational changes from the point of complex formation to interaction with the plasma membrane. These conformation changes provide protection for unprotonated secondary amines in the LPEI backbone by hydrophobic protection of the cholesterol moiety that we termed "unprotonated reserves". Finally, we show that LPC conjugates exploit receptor-mediated endocytosis via the LDL-R pathway with transgene expression levels decreasing nearly 20% after saturating the LDL-R sites on MCF-7 cells with hLDL-R-Ab. PMID:12862439

Furgeson, Darin Y; Chan, Winter S; Yockman, James W; Kim, Sung Wan

2003-01-01

47

MØLLER Energy-Momentum Complex for Higher-Dimensional Spherically Symmetric Spacetime in General Relativity  

NASA Astrophysics Data System (ADS)

We have calculated the total energy-momentum distribution associated with (n+2)-dimensional spherically symmetric model of the universe by using the Møller energy-momentum definition in general relativity (GR). We have found that components of Møller energy and momentum tensor for given spacetimes are different from zero. Also, we are able to get energy and momentum density of various well-known wormholes and black hole models by using the (n+2)-dimensional spherically symmetric metric. Also, our results have been discussed and compared with the results for four-dimensional spacetimes in literature.

Baysal, Hüsnü

2012-12-01

48

An optimal design of symmetric Hinfinity static output feedback controller using LMI for collocated second-order linear system  

Microsoft Academic Search

The symmetric control systems have some interesting properties. This paper studies a class of symmetric system consists of a collocated second-order plant and a static output feedback controller. For the system, it is known that the internal stability and the robustness of the closed-loop system are guaranteed based only on the non-parametric structure condition. Our objective is to propose an

Tomoyuki Nagashio; Takashi Kida

2009-01-01

49

Aluminum complexes incorporating symmetrical and asymmetrical tridentate pincer type pyrrolyl ligands: synthesis, characterization and reactivity study.  

PubMed

A series of aluminum complexes incorporating substituted symmetrical and asymmetrical tridentate pyrrolyl ligands are synthesized conveniently and the treatment of the derivatives with small organic molecules are analyzed. The reaction of lithiated [C4H2NH(2-CH2NH(t)Bu)(5-CH2NR1R2)], where for 1, R1 = R2 = Me; 2, R1 = H, R2 = (t)Bu, with AlCl3 in diethyl ether affords Al[C4H2N(2-CH2NH(t)Bu)(5-CH2NMe2)]Cl2 (3) and Al[C4H2N(2,5-CH2NH(t)Bu)2]Cl2 (4), respectively, in high yields. Furthermore, subjecting 3 and 4 to reaction with one equiv. of LiNMePh in diethyl ether generates Al[C4H2N(2-CH2NH(t)Bu)(5-CH2NMe2)][NMePh]Cl (5) and Al[C4H2N(2,5-CH2NH(t)Bu)2][NMePh]Cl (6), respectively, while eliminating one equiv. of LiCl. The reaction between compound 4 with two equiv. of LiO-Ph-4-Me in diethyl ether yields the aluminum di-phenoxide compound Al[C4H2N(2,5-CH2NH(t)Bu)2](O-Ph-4-Me)2 (7) whereas the combination of 3 and two equiv. of LiNH(t)Bu, produces Al[C4H2N(2-CH2N(t)Bu)(5-CH2NMe2)](NH(t)Bu)(NH2(t)Bu) (8). Additionally, the mixing of 1 and one equiv. of AlMe3 renders Al[C4H2N(2-CH2NH(t)Bu)(5-CH2NMe2)]Me2 (9). Adding one more equiv. of AlMe3 with 9 affords {Al[C4H2N(2-CH2NH(t)Bu)(5-CH2NMe2)AlMe3]Me2} (10), which can also be obtained by treating 1 with two equiv. of AlMe3 directly. The treatment of 9 with one equiv. of 2,6-dimethylphenol in diethyl ether gives the aluminum alkoxide derivative, Al[C4H2N(2-CH2NH(t)Bu)(5-CH2NMe2)](O-C6H3-2,6-Me2)Me (11). Furthermore, the reaction between 9 and one equiv. of 1-ethyl-1-phenyl ketene, initiates the aluminum dimethyl complex Al{C4H2N[2-CH2CEtPh-C(=O)-NH(t)Bu](5-CH2NMe2)}Me2 (12) with a C-N bond breakage and a C-C bond formation. All the Al-derivatives are characterized by (1)H and (13)C NMR spectroscopy and the molecular structures are determined by single crystal X-ray diffractometry in solid state. PMID:23907274

Liu, Pei-Hsin; Chuang, Fu-Jung; Tu, Cheng-Yi; Hu, Ching-Han; Lin, Tzu-Wei; Wang, Yu-Tang; Lin, Chia-Her; Datta, Amitabha; Huang, Jui-Hsien

2013-10-01

50

Trajectories of probe spheres in generalized linear viscoelastic complex fluids.  

PubMed

We have developed a fast simulation that generates a random walk of an isolated probe sphere in a generalized linear viscoelastic complex fluid over a highly extended dynamic range. We introduce a coupled harmonically bound Brownian particle (c-HBBP) model, in which the relaxation modes of the viscoelastic medium are treated as harmonic wells. These wells are coupled to the probe sphere and perform Brownian motion in bound harmonic potentials corresponding to the next-longer relaxation mode, according to the relaxation spectrum of the viscoelastic material. We implement this c-HBBP model by generating variable temporal step sizes that have a uniform distribution in logarithmic time. We create and analyze trajectories for several different viscoelastic complex fluids: a polymer system at its gel point, a dense emulsion system, a blend of two monodisperse polystyrene polymers for which the relaxation spectrum has been measured, and a model anisotropic soft system that shows dense emulsion-like and gel-point behaviors along two orthogonal directions. Except for unusual viscoelastic materials, such as the polymer system at its gel point, the generated trajectories are neither self-similar nor self-affine. The resulting mean square displacements predicted by the c-HBBP model are consistent with the single-particle generalized Stokes-Einstein relation of linear passive microrheology. PMID:25259775

Khan, Manas; Mason, Thomas G

2014-10-30

51

Seismic Sensor orientation by complex linear least squares  

NASA Astrophysics Data System (ADS)

Poorly known orientation of the horizontal components of seismic sensors is a common problem that limits data analysis and interpretation for several acquisition setups, including linear arrays of geophones deployed in borehole installations, ocean bottom seismometers deployed at the sea-floor and surface seismic arrays. To solve this problem we propose an inversion method based on complex linear least squares method. Relative orientation angles, with respect to a reference sensor, are retrieved by minimizing the l2-norm between the complex traces (hodograms) of adjacent pairs of sensors in a least-squares sense. The absolute orientations are obtained in a second step by the polarization analysis of stacked seismograms of a seismic event with known location. This methodology can be applied without restrictions, if the plane wave approximation for wavefields recorded by each pair of sensors is valid. In most cases, it is possible to satisfy this condition by low-pass filtering the recorded waveform. The main advantage of our methodology is that, finding the estimation of the relative orientations of seismic sensors in complex domain is a linear inverse problem, which allows a direct solution corresponding to the global minimum of a misfit function. It is also possible to use simultaneously more than one independent dataset (e.g. using several seismic events simultaneously) to better constrain the solution of the inverse problem itself. Furthermore, by a computational point of view, our method results faster than the relative orientation methods based on waveform cross-correlation. Our methodology can be also applied for testing the correct orientation/alignment of multicomponent land stations in seismological arrays or temporary networks and for determining the absolute orientation of OBS stations and borehole arrays. We first apply our method to real data resembling two different acquisition setups: a borehole sensor array deployed in a gas field located in the Netherlands and a surface network including a seismic array in Chile. The first acquisition setup consists of a linear array of six three-component geophones within a single borehole. Sensor alignment is performed using seismic a regional seismic event occurred in the North sea. A second application focus on broadband seismic sensors deployed in Northern Chile. The sensors from the former Iquique Local Network have been recently reinstalled in a small-scale seismic array configuration, with a single station remaining at the same location in both old and new network geometry. We obtain here relative orientations for both network configurations, using this station as reference, performing the sensor orientation using both low-frequency coherent seismic noise, regional and teleseismic events. This work has been funded by the German BMBF "Geotechnologien" project MINE (BMBF03G0737A).

Grigoli, Francesco; Cesca, Simone; Krieger, Lars; Olcay, Manuel; Tassara, Carlos; Sobiesiak, Monika; Dahm, Torsten

2014-05-01

52

Spreading of infectious diseases on complex networks with non-symmetric transmission probabilities  

E-print Network

We model the spread of a SIS infection on Small World and random networks using weighted graphs. The entry $w_{ij}$ in the weight matrix W holds information about the transmission probability along the edge joining node $v_i$ and node $v_j$. We use the analogy between the spread of a disease on a network and a random walk performed on this network to derive a master equation describing the dynamics of the process. We find conditions under which an epidemic does not break out and investigate numerically the effect of a non-symmetric weight distribution of the initially infected individual on the dynamics of the disease spread.

Britta Daudert; Bai-Lian Li

2006-11-23

53

Complex Dynamics of Compound Vesicles in Linear Flow  

NASA Astrophysics Data System (ADS)

We report first experimental observations of dynamics of compound vesicles in linear flow realized in a microfluidic four-roll mill. We show that while a compound vesicle undergoes the same main tank-treading, trembling (TR), and tumbling regimes, its dynamics are far richer and more complex than that of unilamellar vesicles. A new swinging motion of the inner vesicle is found in TR in accord with simulations. The inner and outer vesicles can exist simultaneously in different dynamical regimes and can undergo either synchronized or unsynchronized motions depending on the filling factor. A compound vesicle can be used as a physical model to study white blood cell dynamics in flow similar to a unilamellar vesicle used successfully to model anucleate cells.

Levant, Michael; Steinberg, Victor

2014-04-01

54

Evaluation of out-of-core computer programs for the solution of symmetric banded linear equations. [simultaneous equations  

NASA Technical Reports Server (NTRS)

FORTRAN coded out-of-core equation solvers that solve using direct methods symmetric banded systems of simultaneous algebraic equations. Banded, frontal and column (skyline) solvers were studied as well as solvers that can partition the working area and thus could fit into any available core. Comparison timings are presented for several typical two dimensional and three dimensional continuum type grids of elements with and without midside nodes. Extensive conclusions are also given.

Dunham, R. S.

1976-01-01

55

Non-centro-symmetric electron diffraction pattern of icosahedral quasicrystal induced by combination of linear phason strain and curvature of Ewald sphere.  

PubMed

Non-centro-symmetric characteristics are observed in the experimental electron diffraction patterns (EDPs) from the icosahedral quasicrystalline precipitates in ZrAlNiCuNb alloys. Different from the well-known breaking of the Friedel's law, where a strong dynamical effect will reveal in EDPs the concealed non-centro-symmetry originated from the crystal structures themselves, the current results can be interpreted in terms of changes in deviation parameters due to a delicate combination of the linear phason strain characteristic of quasicrystals and the curvature of Ewald sphere. After taking this effect into consideration, the corresponding simulated EDPs fit quite well to the experimental data. PMID:24041584

Xiong, Dongxia; Lu, Lu; Wang, Jianbo; Zhao, Dongshan; Sun, Yufeng

2013-01-01

56

Design, Activity, and 2.8 overset{circ}{A} Crystal Structure of a C_2 Symmetric Inhibitor Complexed to HIV-1 Protease  

NASA Astrophysics Data System (ADS)

A two-fold (C_2) symmetric inhibitor of the protease of human immunodeficiency virus type-1 (HIV-1) has been designed on the basis of the three-dimensional symmetry of the enzyme active site. The symmetric molecule inhibited both protease activity and acute HIV-1 infection in vitro, was at least 10,000-fold more potent against HIV-1 protease than against related enzymes, and appeared to be stable to degradative enzymes. The 2.8 angstrom crystal structure of the inhibitor-enzyme complex demonstrated that the inhibitor binds to the enzyme in a highly symmetric fashion.

Erickson, John; Neidhart, David J.; Vandrie, John; Kempf, Dale J.; Wang, Xiu Chun; Norbeck, Daniel W.; Plattner, Jacob J.; Rittenhouse, Judith W.; Turon, Mary; Wideburg, Norman; Kohlbrenner, William E.; Simmer, Robert; Helfrich, Rosalind; Paul, Deborah A.; Knigge, Mark

1990-08-01

57

Spherically symmetric dynamical horizons  

E-print Network

We determine sufficient and necessary conditions for a spherically symmetric initial data set to satisfy the dynamical horizon conditions in the spacetime development. The constraint equations reduce to a single second order linear master equation, which leads to a systematic construction of all spherically symmetric dynamical horizons (SSDH) satisfying certain boundedness conditions. We also find necessary and sufficient conditions for a given spherically symmetric spacetime to contain a SSDH.

Robert Bartnik; Jim Isenberg

2005-12-15

58

Synthesis and metal complexes of chiral c(2)-symmetric diamino-bisoxazoline ligands.  

PubMed

A synthetic route to tetradentate chiral N(4) ligands has been developed with the aim to study the potential of corresponding iron and manganese complexes as catalysts for enantioselective epoxidation. These ligands, which contain two oxazoline rings and two trialkylamino groups as coordinating units, are readily prepared in enantiomerically pure form by the reaction of chiral 2-chloromethyloxazolines with achiral N,N'-dimethylethane-1,2-diamine or chiral (R,R)-N,N'-dimethylcyclohexane-1,2-diamine. The ligands derived from N,N'-dimethylethane-1,2-diamine reacted with anhydrous metal halides MnCl(2) and FeCl(2) in a stereoselective manner to give octahedral mononuclear complexes that have the general formula Delta-[(L)MCl(2)]. In contrast, the ligands derived from N,N'-dimethylcyclohexane-1,2-diamine formed complexes with different coordination modes depending on the diastereomer employed: in one case the metal ion was found to be pentacoordinate, in the other case a hexacoordinated complex was observed. The structure of a series of Fe and Mn complexes was determined by X-ray analysis. The coordination chemistry of these ligands was further studied by X-ray and NMR analyses of the diamagnetic isostructural complexes [(L)ZnCl(2)]. Analogous ionic complexes, which were prepared by removing chloride with silver trifluoromethanesulfonate or hexafluoroantimonate, were tested as catalysts for the epoxidation of olefins. PMID:17721893

Guillemot, Geoffroy; Neuburger, Markus; Pfaltz, Andreas

2007-01-01

59

C{sub 2}-symmetric Copper(II) complexes as chiral Lewis acids  

SciTech Connect

Two new Cu(II)-derived Lewis acid catalysts 1 and 2 have been prepared and their utility as catalysts in the Diels-Alder reaction documented. While complex 1 is effective in catalyzing the cycloaddition of unsaturated aldehyde dienophiles with cyclopentadiene complex 2 is optimal for imide dienophiles. This study provides a rational basis for the design of Lewis acids based on the coordinating capacity of cationic Cu(II) complexes which possess sufficient Lewis acidity to catalyze a range of synthetically useful Diels-Alder reactions. In particular, documentation of the importance of counterion structure in the use of cationic metal centers as Lewis acids has been made for the first time.

Evans, D.A.; Murry, J.A.; Matt, P. von [Harvard Univ., Cambridge, MA (United States)] [and others

1995-12-01

60

Assembly of symmetrical and unsymmetrical platinum(ii) rollover complexes with bidentate phosphine ligands.  

PubMed

The reaction of the cyclometalated rollover complex [Pt(bpy-H)(Me)(DMSO)] (bpy-H = cyclometalated 2,2'-bipyridine) with two diphosphines, dppm (1,1-bis(diphenylphosphino)methane) and dppe (1,2-bis(diphenylphosphino)ethane), was investigated. According to the reaction conditions, dppm behaves as a monodentate, bridging or chelated ligand, whereas dppe gave only chelated species. Some aspects of the reactivity of the isolated species were studied, including protonation with [H3O·18-crown-6][BF4] and coordination reactions of mononuclear complexes, obtaining, inter alia, rare examples of unsymmetrical organometallic species with bridging dppm. PMID:25162179

Maidich, Luca; Zuri, Giuseppina; Stoccoro, Sergio; Cinellu, Maria Agostina; Zucca, Antonio

2014-09-16

61

On the experimental verification of quantum complexity in linear optics  

E-print Network

The first quantum technologies to solve computational problems that are beyond the capabilities of classical computers are likely to be devices that exploit characteristics inherent to a particular physical system, to tackle a bespoke problem suited to those characteristics. Evidence implies that the detection of ensembles of photons, which have propagated through a linear optical circuit, is equivalent to sampling from a probability distribution that is intractable to classical simulation. However, it is probable that the complexity of this type of sampling problem means that its solution is classically unverifiable within a feasible number of trials, and the task of establishing correct operation becomes one of gathering sufficiently convincing circumstantial evidence. Here, we develop scalable methods to experimentally establish correct operation for this class of sampling algorithm, which we implement with two different types of optical circuits for 3, 4, and 5 photons, on Hilbert spaces of up to 50,000 dimensions. With only a small number of trials, we establish a confidence >99% that we are not sampling from a uniform distribution or a classical distribution, and we demonstrate a unitary specific witness that functions robustly for small amounts of data. Like the algorithmic operations they endorse, our methods exploit the characteristics native to the quantum system in question. Here we observe and make an application of a "bosonic clouding" phenomenon, interesting in its own right, where photons are found in local groups of modes superposed across two locations. Our broad approach is likely to be practical for all architectures for quantum technologies where formal verification methods for quantum algorithms are either intractable or unknown.

Jacques Carolan; Jasmin D. A. Meinecke; Pete Shadbolt; Nicholas J. Russell; Nur Ismail; Kerstin Wörhoff; Terry Rudolph; Mark G. Thompson; Jeremy L. O'Brien; Jonathan C. F. Matthews; Anthony Laing

2013-11-12

62

On the solutions of some linear complex quaternionic equations.  

PubMed

Some complex quaternionic equations in the type AX - XB = C are investigated. For convenience, these equations were called generalized Sylvester-quaternion equations, which include the Sylvester equation as special cases. By the real matrix representations of complex quaternions, the necessary and sufficient conditions for the solvability and the general expressions of the solutions are obtained. PMID:25101318

Bolat, Cennet; ?pek, Ahmet

2014-01-01

63

On the Solutions of Some Linear Complex Quaternionic Equations  

PubMed Central

Some complex quaternionic equations in the type AX ? XB = C are investigated. For convenience, these equations were called generalized Sylvester-quaternion equations, which include the Sylvester equation as special cases. By the real matrix representations of complex quaternions, the necessary and sufficient conditions for the solvability and the general expressions of the solutions are obtained. PMID:25101318

Ipek, Ahmet

2014-01-01

64

Linear phase variable 2-D filter design using real-complex decomposition  

Microsoft Academic Search

This paper proposes a new method for designing two-dimensional (2-D) variable digital filters with arbitrary variable magnitude characteristics and linear phases. By combining the given variable magnitude specification with linear phase specification, we first form a variable 2-D frequency response specification. Then we propose a real-complex decomposition method for decomposing the complex-valued variable specification into real-valued and complex-valued components. Finally,

Tian-Bo Deng

1997-01-01

65

Does linear separability really matter? Complex visual search is explained by simple search  

PubMed Central

Visual search in real life involves complex displays with a target among multiple types of distracters, but in the laboratory, it is often tested using simple displays with identical distracters. Can complex search be understood in terms of simple searches? This link may not be straightforward if complex search has emergent properties. One such property is linear separability, whereby search is hard when a target cannot be separated from its distracters using a single linear boundary. However, evidence in favor of linear separability is based on testing stimulus configurations in an external parametric space that need not be related to their true perceptual representation. We therefore set out to assess whether linear separability influences complex search at all. Our null hypothesis was that complex search performance depends only on classical factors such as target-distracter similarity and distracter homogeneity, which we measured using simple searches. Across three experiments involving a variety of artificial and natural objects, differences between linearly separable and nonseparable searches were explained using target-distracter similarity and distracter heterogeneity. Further, simple searches accurately predicted complex search regardless of linear separability (r = 0.91). Our results show that complex search is explained by simple search, refuting the widely held belief that linear separability influences visual search. PMID:24029822

Vighneshvel, T.; Arun, S. P.

2013-01-01

66

Design of in vitro Symmetric Complexes and Analysis by Hybrid Methods Reveal Mechanisms of HIV Capsid Assembly  

PubMed Central

Unlike the capsids of icosahedral viruses, retroviral capsids are pleomorphic, with variably curved, closed fullerene shells composed of ~250 hexamers and exactly 12 pentamers of the viral CA protein. Structures of CA oligomers have been difficult to obtain because the subunit-subunit interactions are inherently weak, and CA tends to spontaneously assemble into capsid-like particles. Guided by a cryoEM-based model of the hexagonal lattice of HIV-1 CA, we used a two-step biochemical strategy to obtain soluble CA hexamers and pentamers for crystallization. First, each oligomer was stabilized by engineering disulfide cross-links between the N-terminal domains of adjacent subunits. Second, the cross-linked oligomers were prevented from polymerizing into hyperstable, capsid-like structures by mutations that weakened the dimeric association between the C-terminal domains that link adjacent oligomers. The X-ray structures revealed that the oligomers are comprised of a fairly rigid, central symmetric ring of N-terminal domains encircled by mobile C-terminal domains. Assembly of the quasi-equivalent oligomers requires remarkably subtle rearrangements in inter-subunit quaternary bonding interactions, and appears to be controlled by an electrostatic switch that favors hexamers over pentamers. An atomic model of the complete HIV-1 capsid was then built using the fullerene cone as a template. Rigid-body rotations around two assembly interfaces are sufficient to generate the full range of continuously varying lattice curvature in the fullerene cone. The steps in determining this HIV-1 capsid atomic model exemplify how structural biology can be leveraged by the use of hybrid methods, a powerful approach for exploring the structure of pleomorphic macromolecular complexes. PMID:21762799

Yeager, Mark

2011-01-01

67

Linear genetics, non-linear epigenetics: Complementary approaches to understanding complex diseases  

Microsoft Academic Search

Recent discoveries and rediscoveries in molecular and cell biology, in population and evolutionary biology, and in disease\\u000a natural history raise new doubts about the ability of genetic analysis alone to predict multifactorial (polygenic) human diseases\\u000a and other complex phenotypes. These doubts serve to redirect our attention to epigenetic regulation as a second informational\\u000a system in parallel with the genome. Epigenetic

Richard C. Strohman

1995-01-01

68

Design of linear phase variable 2-D digital filters using real-complex decomposition  

Microsoft Academic Search

Variable digital filters are especially difficult to design when the given variable design specifications are complicated. This paper proposes a new method for designing two dimensional (2-D) variable digital filters with arbitrarily variable, magnitude characteristics and linear phase. By combining variable magnitude specification with linear phase specification, we first form a variable 2-D frequency response specification, which is complex-valued. Then

Tian-Bo Deng

1998-01-01

69

A numerical study of the Schrodinger-Newton equation 1: Perturbing the spherically-symmetric stationary states  

E-print Network

We consider the linear stability of the spherically-symmetric stationary solutions of the Schrodinger-Newton equations. We find that the ground state is linearly stable, with only imaginary eigenvalues, while the n-th excited state has n quadruples of complex eigenvalues as well as purely imaginary ones and so is linearly unstable.

R. Harrison; I. Moroz; K. P. Tod

2002-08-30

70

Symmetric factorization Riccati equations  

E-print Network

Symmetric factorization Riccati equations and Bezoutians collaboration with I. Karelin and L. Lerer() - C(I - A)-1B is analytic over the whole complex plane, and · (A, B, C) is minimal. #12;Special case�-invariant subspace is of the form M� = Im X I , where X = X satisfies the algebraic Riccati equation XCCX + X(A - BC

71

COMPLEXITY REGULARIZED VIDEO WATERMARKING VIA QUANTIZATION OF PSEUDORANDOM SEMI-GLOBAL LINEAR STATISTICS  

Microsoft Academic Search

In this paper, we propose a semi-blind video watermarking scheme for the verification problem, where mark embedding is car- ried out by designing a complexity-adaptive watermark signal via solving a constrained optimization problem. By adding the resulting watermark to the unmarked host, we effectively quantize pseudo- random linear statistics of the host in the wavelet domain using a secret codebook.

Oztan Harmanci; M. KivancMihcak

2005-01-01

72

Theory of the Spatial Structure of Non-linear Modes in Novel and Complex Laser Cavities  

E-print Network

ICTON 2007 Theory of the Spatial Structure of Non-linear Modes in Novel and Complex Laser Cavities and applied to conventional edge-emitting lasers and to lasers with chaotic or random cavities. The theory solves a long-standing problem in lasing theory: how to describe the multi-mode lasing states of an open

Rotter, Stefan

73

Linear phase 1-D variable filter design based on real-complex decomposition  

Microsoft Academic Search

Variable digital filters are especially difficult to design in the case that the given variable design specifications are complicated. This paper proposes a new method for designing variable one-dimensional (1-D) digital filters approximating both the given variable magnitude specification and the linear phase specification based on the complex array decomposition

Tian-Bo Deng

1997-01-01

74

Power-SLAM: A Linear-Complexity, Anytime Algorithm for SLAM  

E-print Network

1 Power-SLAM: A Linear-Complexity, Anytime Algorithm for SLAM Esha D. Nerurkar, Student Member Filter (EKF)-based estimator for simultaneous localization and mapping (SLAM) with processing SLAM, is based on three key ideas. Firstly, by introducing the Global Map Postponement method

Roumeliotis, Stergios I.

75

Synthesis, DNA-cleaving activities and cytotoxicities of C?-symmetrical dipyrrole-polyamide dimer-based Cu(II) complexes: a comparative study.  

PubMed

Two C?-symmetrical dipyrrole-polyamide dimers 2 and 3 that were tethered with triethylenetetramine and spermine, respectively, and their corresponding Cu(II) complexes 2@Cu(2+) and 3@Cu(2+), were synthesized and fully characterized. Agarose gel electrophoresis studies on pBR322 DNA cleavage indicated that both Cu(II) complexes exhibited potent DNA-cleaving activities under physiological conditions, most probably via an oxidative mechanism. Kinetic assay indicate that 2@Cu(2+) and 3@Cu(2+) exhibited comparable catalytic efficiency with the Cu(II) complex of their 2,2'-(ethane-1,2-diylbis(oxy))diethanamine-tethered analog 1. The finding that compounds 2 and 3 showed higher Cu(II) ion-complexing abilities than compound 1, suggests that strong metal complexation does not necessarily lead to an enhancement in the catalytic efficiency of a DNA-cleaving agent. In addition, three Cu(II) complexes displayed moderate inhibitory activities toward three tumor cell lines. PMID:23832255

Zhou, Chun-Qiong; Lin, Yan-Ling; Yang, Jian-Wei; Chen, Jin-Xiang; Chen, Wen-Hua

2013-08-01

76

Structures of KcsA in complex with symmetrical quaternary ammonium compounds reveal a hydrophobic binding site.  

PubMed

Potassium channels allow for the passive movement of potassium ions across the cell membrane and are instrumental in controlling the membrane potential in all cell types. Quaternary ammonium (QA) compounds block potassium channels and have long been used to study the functional and structural properties of these channels. Here we describe the interaction between three symmetrical hydrophobic QAs and the prokaryotic potassium channel KcsA. The structures demonstrate the presence of a hydrophobic pocket between the inner helices of KcsA and provide insight into the binding site and blocking mechanism of hydrophobic QAs. The structures also reveal a structurally hidden pathway between the central cavity and the outside membrane environment reminiscent of the lateral fenestration observed in sodium channels that can be accessed through small conformational changes in the pore wall. We propose that the hydrophobic binding pocket stabilizes the alkyl chains of long-chain QA molecules and may play a key role in hydrophobic drug binding in general. PMID:25093676

Lenaeus, Michael J; Burdette, Dylan; Wagner, Tobias; Focia, Pamela J; Gross, Adrian

2014-08-19

77

Multi-cavity complex controller with vector simulator for TESLA technology linear accelerator  

NASA Astrophysics Data System (ADS)

A digital control, as the main part of the Low Level RF system, for superconducting cavities of a linear accelerator is presented. The FPGA based controller, supported by MATLAB system, was developed to investigate a novel firmware implementation. The complex control algorithm based on the non-linear system identification is the proposal verified by the preliminary experimental results. The general idea is implemented as the Multi-Cavity Complex Controller (MCC) and is still under development. The FPGA based controller executes procedure according to the prearranged control tables: Feed-Forward, Set-Point and Corrector unit, to fulfill the required cavity performance: driving in the resonance during filling and field stabilization for the flattop range. Adaptive control algorithm is applied for the feed-forward and feedback modes. The vector Simulator table has been introduced for an efficient verification of the FPGA controller structure. Experimental results of the internal simulation, are presented for a cavity representative condition.

Czarski, Tomasz; Pozniak, Krzysztof T.; Romaniuk, Ryszard S.; Szewinski, Jaroslaw

2008-01-01

78

Low-Complexity Design of Variable Bandedge Linear Phase FIR Filters With Sharp Transition Band  

Microsoft Academic Search

This paper presents a very low-complexity design of variable bandedge linear phase finite-impulse-response (FIR) filters with fixed sharp transition width. The idea is to first decompose the input signal into several channels in the frequency domain. The channel(s) involved with the transition band of the variable filter due to the variation of the bandedge is (are) shaped to produce the

Ya Jun Yu; Yong Ching Lim; Dong Shi

2009-01-01

79

Linear response theory for statistical ensembles in complex systems with time-periodic forcing  

Microsoft Academic Search

New linear response formulas for unperturbed chaotic (stochastic) complex dynamical\\u000asystems with time periodic coefficients are developed here. Such time periodic systems arise\\u000anaturally in climate change studies due to the seasonal cycle. These response formulas are developed\\u000athrough the mathematical interplay between statistical solutions for the time-periodic dynamical\\u000asystems and the related skew-product system. This interplay is utilized to

Andrew J. Majda; Xiaoming Wang

2010-01-01

80

A Simple Modification in CMA-ES Achieving Linear Time and Space Complexity  

Microsoft Academic Search

This paper proposes a simple modification of the Covariance Matrix Adaptation Evolution Strategy (CMA-ES) for high dimensional objective func- tions, reducing the internal time and space complexity from quadratic to linear. The covariance matrix is constrained to be diagonal and the resulting algorithm, sep-CMA-ES, samples each coordinate independently. Because the model com- plexity is reduced, the learning rate for the

Raymond Ros; Nikolaus Hansen

2008-01-01

81

1. Mono((8)annulene)Uranium(4) half-sandwich complexes, 2. Novel syntheses of symmetrically substituted cyclooctatetetraenes  

SciTech Connect

A reproducible, high-yield synthesis of mono((8)annulene)uranium(4)dichloride (1) is reported, along with the X-ray crystal structural of the bis(pyridine) adduct. Metathesis reactions of the half-sandwich complex 1 with a variety of simple alkyl and alkoxy reagents failed to generate any isolable mono-ring complexes. Reactions of 1 with polydentate, delocalized anions did produce stable derivatives, including mono((8)annulene)uranium(4)bis(acetylacetonate) (4). An X-ray crystal structure of 4 is reported.

Boussie, T.R.

1991-10-01

82

1. Mono([8]annulene)Uranium(4) half-sandwich complexes, 2. Novel syntheses of symmetrically substituted cyclooctatetetraenes  

SciTech Connect

A reproducible, high-yield synthesis of mono([8]annulene)uranium(4)dichloride (1) is reported, along with the X-ray crystal structural of the bis(pyridine) adduct. Metathesis reactions of the half-sandwich complex 1 with a variety of simple alkyl and alkoxy reagents failed to generate any isolable mono-ring complexes. Reactions of 1 with polydentate, delocalized anions did produce stable derivatives, including mono([8]annulene)uranium(4)bis(acetylacetonate) (4). An X-ray crystal structure of 4 is reported.

Boussie, T.R.

1991-10-01

83

Surface chemistry of the linear chromium chain complex on GaN(0001)  

SciTech Connect

Better understanding about the chemistry of the organometallic chain complexes reacting on the solid surface can foster concepts of nanowire fabrication which are central to the continued advance of the electronic and optoelectronic industries. In this study, the adsorption and thermal reactivity of a trinuclear chromium chain complex, tetrakis (2,2{sup '}-dipyridylamino)chromium(VI) chloride, on the GaN(0001) surface were investigated using x-ray photoelectron spectroscopy, temperature-programmed desorption, and static secondary ion mass spectrometry in order to obtain some insight into the bonding changes involved in the reaction of the linear metal chain complex on the compound semiconductor surface. One of the two terminal Cr-Cl bonds of the complex may be cleaved upon adsorption at 110 K, leading to the formation of the Ga-Cl bonds on the surface, although some complexes remained intact upon adsorption and bonded strongly to the surface. No ligand was dissociated from the chromium chain complex during the adsorption. The Cl-cleaved complex residue preserved its original chemical configuration. Both the Cl-cleaved and the intact complexes in the first layer were stable on the surface in the substrate temperature range between 110 and 260 K. A partial decomposition in which some ligands were dissociated from the adsorbed complex took place before the substrate temperature reaching 400 K. Additional Cr-Cl bonds were disrupted, resulting in a larger population of Ga-Cl bonds on the surface. Further thermal reaction at higher temperatures led to the dominance of the Ga-Cl bonding for the Cl presence on the surface. Surface etching of Ga by the dissociated Cl atoms started at a substrate temperature of {approx}525 K and the etching rate reached its maximum at {approx}590 K.

Lung, C.-H.; Peng, S.-M.; Chang, C.-C. [Department of Chemistry, National Taiwan University, Taipei, Taiwan 10617 (China)

2004-09-01

84

The effects of asymmetric vs. symmetric probability of targets following probe and irrelevant stimuli in the complex trial protocol for detection of concealed information with P300.  

PubMed

The complex trial protocol (CTP, [J.P. Rosenfeld, E. Labkovsky, M. Winograd, M.A. Lui, C. Vandenboom & E. Chedid (2008), The complex trial protocol (CTP): a new, countermeasure-resistant, accurate P300-based method for detection of concealed information. Psychophysiology, 45, 906-919.]) is a sensitive, new, countermeasure-resistant, P300-based concealed information protocol in which a first stimulus (Probe or Irrelevant) is followed after about 1.4-1.8 s by a Target or Non-Target second stimulus within one trial. It has been previously run with a potentially confounding asymmetric conditional probability of Targets following Probes vs. Irrelevants. This present study compared asymmetric vs. symmetric conditional probability groups and found no significant differences in detection rates or Probe-minus-Irrelevant P300 differences between groups. Group differences were seen in error rates and reaction times (RT) to second stimuli. These differences were, however, not diagnostic for deception vs. truth-telling, and were attributable to response perseveration. PMID:19374912

Rosenfeld, J Peter; Tang, Monica; Meixner, John; Winograd, Michael; Labkovsky, Elena

2009-08-01

85

Higher derivative discontinuous solutions to linear ordinary differential equations: A new route to complexity?  

E-print Network

We present a new one parameter family of second derivative discontinuous solutions to the simplest scale invariant linear ordinary differential equation. We also point out how the construction could be extended to generate families of higher derivative discontinuous solutions as well. The discontinuity can occur only for a subset of even order derivatives, viz.,2nd, 4th, 8th, 16th, ....The solutions are shown to break the discrete parity (reflection) symmetry of the underlying equation. These results are expected to gain significance in the contemporary search of a new {\\em dynamical principle} for understanding complex phenomena in Nature.

Dhurjati Prasad Datta; Manoj Kumar Bose

2010-01-10

86

Simply Symmetric  

ERIC Educational Resources Information Center

Symmetry is found in the visual arts, architecture and design of artefacts since the earliest time. Many natural objects, both organic and inorganic, display symmetry: from microscopic crystals and sub-atomic particles to macro-cosmic galaxies. Today it features strongly in higher mathematics such as Linear and Abstract Algebra, Projective and…

de Villiers, Michael

2011-01-01

87

Determination of stability constants for complexes from catalytic linear scan voltammetric currents  

NASA Astrophysics Data System (ADS)

A linear scan voltammetric method for determining stability constants for complexes formed in the bulk solution between metal ions and ligands that catalyse their reduction is proposed. The method is based on the pure limiting kinetic current produced in the electrocatalytic process, which is recorded following preconcentration of ligands by convective transport on a hanging mercury drop electrode until surface excesses reach the values for adsorption equilibrium with the bulk solution. The stability constant for the Ni(o-phenylenediamine)2+ complex provided by the proposed method is reasonably consistent with reported values obtained from catalytic dc polarographic currents. Une méthode voltammétrique à balayage linéaire de potentiel a été développée pour la détermination des constants de stabilité des complexes des ions métalliques avec des ligands capables de catalyser leur réduction. La méthode utilise le courant limite cinétique produite par la réaction électrocatalytique. Cette courante est enregistrée après une période de préconcentration du ligand à la surface de l'électrode de goutte pendante de mercure jusqu'à la concentration superficiale atteint la valeur correspondante à l'équilibre d'adsorption avec la solution. La valeur de la constant de stabilité mesurée avec cette méthode pour le complexe Ni(o-phénylénédiamine) est d'accord avec les valeurs obtenues de la courant catalytique en polarographie de courant continu.

Muñiz Alvarez, J. L.; García Calzón, J. A.; López Fonseca, J. M.

1998-05-01

88

Atropisomeric discrimination in new Ru(II) complexes containing the C(2)-symmetric didentate chiral phenyl-1,2-bisoxazolinic ligand.  

PubMed

A new family of Ru(II) complexes containing the tridentate meridional 2,2':6',2''-terpyridine (trpy) ligand, a C(2)-symmetric didentate chiral oxazolinic ligand 1,2-bis[4'-alkyl-4',5'-dihydro-2'-oxazolyl]benzene (Phbox-R, R = Et or iPr), and a monodentate ligand, of general formula [Ru(Y)(trpy)(Phbox-R)](n+) (Y = Cl, H(2)O, py, MeCN, or 2-OH-py (2-hydroxypyridine)) have been prepared and thoroughly characterized. In the solid state the complexes have been characterized by IR spectroscopy and by X-ray diffraction analysis in two cases. In solution, UV/Vis, cyclic voltammetry (CV), and one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy techniques have been used. We have also performed density functional theory (DFT) calculations with these complexes to interpret and complement experimental results. The oxazolinic ligand Phbox-R exhibits free rotation along the phenyloxazoline axes. Upon coordination this rotation is restricted by an energy barrier of 26.0 kcal mol(-1) for the case of [Ru(trpy)(Phbox-iPr)(MeCN)](2+) thus preventing its potential interconversion. Furthermore due to steric effects the two atropisomers differ in energy by 5.7 kcal mol(-1) and as a consequence only one of them is obtained in the synthesis. Subtle but important structural effects occur upon changing the monodentate ligands that are detected by NMR spectroscopy in solution and interpreted by using their calculated DFT structures. PMID:16416493

Sala, Xavier; Plantalech, Elena; Romero, Isabel; Rodríguez, Montserrat; Llobet, Antoni; Poater, Albert; Duran, Miquel; Solà, Miquel; Jansat, Susanna; Gómez, Montserrat; Parella, Teodor; Stoeckli-Evans, Helen; Benet-Buchholz, Jordi

2006-03-20

89

Power-SLAM: A Linear-Complexity, Consistent Algorithm for SLAM Esha D. Nerurkar and Stergios I. Roumeliotis  

E-print Network

Power-SLAM: A Linear-Complexity, Consistent Algorithm for SLAM Esha D. Nerurkar and Stergios I (SLAM) with processing requirements that are linear in the number of features in the map. The proposed of the proposed algorithm (Power-SLAM) when compared to the quadratic computational cost standard EKF-based SLAM

Roumeliotis, Stergios I.

90

Investigation of non-linear free vibrations of fully clamped symmetrically laminated carbon-fibre-reinforced PEEK (AS4\\/APC2) rectangular composite panels  

Microsoft Academic Search

In an earlier publication, the optimum parameters for ultrasonic welding of carbon-fibre\\/PEEK (AS4\\/APC-2) composites have been determined; the physico-chemical properties and fracture surface morphology of modes I and II have been described. The objective of this paper is further to extend our understanding of the dynamic behaviour of the AS4\\/APC-2 by the theoretical modelling of its geometrically non-linear dynamic behaviour

B. Harras; R. Benamar; R. G. White

2002-01-01

91

Experimental and theoretical study of lanthanide complexes based on linear and macrocyclic polyaminopolycarboxylic acids containing pyrazolylethyl arms.  

PubMed

We report the synthesis of two novel Gd(III)-complexes derived from linear and macrocyclic polyaminopolycarboxylic acids 1 and 2, which contain a 3,5- dimethylpyrazolyl-ethyl arm, and a study of their relaxivity properties. The relationships between the experimental and theoretical results have provided interesting information about the kinetic and thermodynamic stability of these complexes. PMID:17962766

Pérez-Mayoral, Elena; Soriano, Elena; Cerdán, Sebastián; Ballesteros, Paloma

2006-01-01

92

Modelling the Burstiness of Complex Space Plasmas Using Linear Fractional Stable Motion  

NASA Astrophysics Data System (ADS)

The Earth's magnetosphere is quite clearly “complex" in the everyday sense of the word. However, in the last 15 to 20 years there has been a growing thread in space physics (e.g. Freeman & Watkins [Science, 2002] , Chapman & Watkins [Space Science Reviews, 2001]) using and developing some of the emerging science of complex systems (e.g. Sornette, 2nd Edition, 2004). A particularly well-studied set of system properties has been derived from those used in the study of critical phenomena, notably correlation functions, power spectra, distributions of bursts above a threshold, and so on (e.g. Watkins [Nonlinear Processes in Geophysics, 2002]). These have revealed behaviours familiar from many other complex systems, such as burstiness, long range dependence, heavy tailed probability distributions and so forth. The results of these studies are typically interpreted within existing paradigms, most notably self-organised criticality. However, just as in other developing areas of complexity science (Sornette, op. cit.; Watkins & Freeman [Science, 2008]), it is increasingly being realised that the diagnostics in use have not been extensively studied outside the context in which they were originally proposed. This means that, for example, it is not well established what the expected distribution of bursts above a fixed threshold will be for time series other than Brownian (or fractional Brownian) motion. We will describe some preliminary investigations (Watkins et al [Physical Review E, 2009]) into the burst distribution problem, using Linear Fractional Stable Motion as a controllable toy model of a process exhibiting both long-range dependence and heavy tails. A by product of the work was a differential equation for LFSM (Watkins et al, op cit), which we also briefly discuss. Current and future work will also focus on the thorny problem of distinguishing turbulence from SOC in natural datasets (Watkins et al; Uritsky et al [Physical Review Letters, 2009]) with limited dynamic range, an area which will also be briefly discussed.

Watkins, N. W.; Rosenberg, S. J.; Chapman, S. C.; Sanchez, R.; Credgington, D.

2009-12-01

93

Complex adsorption of short linear alkanes in the flexible metal-organic-framework MIL-53(Fe).  

PubMed

This investigation is based on a combination of experimental tools completed by a computational approach to deeply characterize the unusual adsorption behavior of the flexible MIL-53(Fe) in the presence of short linear alkanes. In contrast to the aluminum or chromium analogues we previously reported, the iron MIL-53 solid, which initially exhibits a closed structure in the dry state, shows more complex adsorption isotherms with multisteps occurring at pressures that depend on the nature of the alkane. This behavior has been attributed to the existence of four discrete pore openings during the whole adsorption process. Molecular simulations coupled with in situ X-ray powder diffraction were able to uncover these various structural states. PMID:19697934

Llewellyn, P L; Horcajada, P; Maurin, G; Devic, T; Rosenbach, N; Bourrelly, S; Serre, C; Vincent, D; Loera-Serna, S; Filinchuk, Y; Férey, G

2009-09-16

94

Linear-algebraic bath transformation for simulating complex open quantum systems  

E-print Network

In studying open quantum systems, the environment is often approximated as a collection of non-interacting harmonic oscillators, a configuration also known as the star-bath model. It is also well known that the star-bath can be transformed into a nearest-neighbor interacting chain of oscillators. The chain-bath model has been widely used in renormalization group approaches. The transformation can be obtained by recursion relations or orthogonal polynomials. Based on a simple linear algebraic approach, we propose a bath partition strategy to reduce the system-bath coupling strength. As a result, the non-interacting star-bath is transformed into a set of weakly-coupled multiple parallel chains. The transformed bath model allows complex problems to be practically implemented on quantum simulators, and it can also be employed in various numerical simulations of open quantum dynamics.

Huh, Joonsuk; Fujita, Takatoshi; Yung, Man-Hong; Aspuru-Guzik, Alán

2014-01-01

95

Massive parallelization of serial inference algorithms for a complex generalized linear model  

PubMed Central

Following a series of high-profile drug safety disasters in recent years, many countries are redoubling their efforts to ensure the safety of licensed medical products. Large-scale observational databases such as claims databases or electronic health record systems are attracting particular attention in this regard, but present significant methodological and computational concerns. In this paper we show how high-performance statistical computation, including graphics processing units, relatively inexpensive highly parallel computing devices, can enable complex methods in large databases. We focus on optimization and massive parallelization of cyclic coordinate descent approaches to fit a conditioned generalized linear model involving tens of millions of observations and thousands of predictors in a Bayesian context. We find orders-of-magnitude improvement in overall run-time. Coordinate descent approaches are ubiquitous in high-dimensional statistics and the algorithms we propose open up exciting new methodological possibilities with the potential to significantly improve drug safety. PMID:25328363

Suchard, Marc A.; Simpson, Shawn E.; Zorych, Ivan; Ryan, Patrick; Madigan, David

2014-01-01

96

Complex scattering lengths for ultracold He collisions with rotationally excited linear and nonlinear molecules  

SciTech Connect

The translational and internal level cooling of atoms and molecules in ultracold gases results from a combination of elastic and inelastic collisional processes. While elastic collisions lead to rapid thermalization, exoergic inelastic collisions may lead to heating and trap loss. To date, most collisional studies have targeted low-lying levels of diatomic molecules. Here we investigate inelastic quenching and elastic scattering of rotationally excited linear (H{sub 2}, HD, CO, O{sub 2}, and CO{sub 2}) and nonlinear (H{sub 2}O and NH{sub 3}) molecules in ultracold collisions with He and report the corresponding complex scattering lengths. It has been found that the ratio of the imaginary component {beta} to the real component {alpha} of the scattering length generally increases with decreasing rotational constant for linear molecules. With the exception of CO, {beta} becomes significantly smaller than {alpha} as the energy gap for rotational transitions increases. In all cases, {beta} decreases with rotational energy gap for relatively large rotational excitation, allowing for convenient fits to an exponential energy gap formula. Excited rotational levels of H{sub 2} and HD appear to be collisionally stable due to the very low values of {beta}/{alpha}. Rotationally excited H{sub 2}O also appears to be a viable candidate for He buffer gas cooling due to relatively small values of {beta}.

Yang Benhui; Stancil, P. C. [Department of Physics and Astronomy and the Center for Simulational Physics, University of Georgia, Athens, Georgia 30602 (United States); Forrey, R. C. [Department of Physics, Penn State University, Berks Campus, Reading, Pennsylvania 19610 (United States); Balakrishnan, N. [Department of Chemistry, University of Nevada Las Vegas, Las Vegas, Nevada 89154 (United States)

2010-11-15

97

LETTER TO THE EDITOR: {\\cal P}{\\cal T} -symmetric quantum theory defined in a Krein space  

NASA Astrophysics Data System (ADS)

We provide a mathematical framework for {\\cal P}{\\cal T} -symmetric quantum theory, which is applicable irrespective of whether a system is defined on {\\bb R} or a complex contour, whether {\\cal P}{\\cal T} symmetry is unbroken, and so on. The linear space in which {\\cal P}{\\cal T} -symmetric quantum theory is naturally defined is a Krein space constructed by introducing an indefinite metric into a Hilbert space composed of square integrable complex functions in a complex contour. We show that in this Krein space every {\\cal P}{\\cal T} -symmetric operator is {\\cal P} -Hermitian if and only if it has transposition symmetry as well, from which the characteristic properties of the {\\cal P}{\\cal T} -symmetric Hamiltonians found in the literature follow. Some possible ways to construct physical theories are discussed within the restriction to the class K(H).

Tanaka, Toshiaki

2006-06-01

98

A new ion mobility-linear ion trap instrument for complex mixture analysis.  

PubMed

A new instrument that couples a low-pressure drift tube with a linear ion trap mass spectrometer is demonstrated for complex mixture analysis. The combination of the low-pressure separation with the ion trapping capabilities provides several benefits for complex mixture analysis. These include high sensitivity, unique ion fragmentation capabilities, and high reproducibility. Even though the gas-phase separation and the mass measurement steps are each conducted in an ion filtering mode, detection limits for mobility-selected peptide ions are in the tens of attomole range. In addition to ion separation, the low-pressure drift tube can be used as an ion fragmentation cell yielding mobility-resolved fragment ions that can be subsequently analyzed by multistage tandem mass spectrometry (MS(n)) methods in the ion trap. Because of the ion trap configuration, these methods can be comprised of any number (limited by ion signal) of collision-induced dissociation (CID) and electron transfer dissociation (ETD) processes. The high reproducibility of the gas-phase separation allows for comparison of two-dimensional ion mobility spectrometry (IMS)-MS data sets in a pixel-by-pixel fashion without the need for data set alignment. These advantages are presented in model analyses representing mixtures encountered in proteomics and metabolomics experiments. PMID:25068446

Donohoe, Gregory C; Maleki, Hossein; Arndt, James R; Khakinejad, Mahdiar; Yi, Jinghai; McBride, Carroll; Nurkiewicz, Timothy R; Valentine, Stephen J

2014-08-19

99

Affine Stanley symmetric functions  

Microsoft Academic Search

We define a new family of symmetric functions which are affine analogues of Stanley symmetric functions. We establish basic properties of these functions including symmetry, dominance and conjugation. We conjecture certain positivity properties in terms of a subfamily of symmetric functions called affine Schur functions. As applications, we show how affine Stanley symmetric functions generalise the (dual of the) $k$-Schur

Thomas Lam

2005-01-01

100

Synthesis and structures of niobium(V) complexes stabilized by linear-linked aryloxide trimers.  

PubMed

The preparation and characterization of a series of niobium(V) complexes that incorporate the linear-linked aryloxide trimers 2,6-bis(4,6-dimethylsalicyl)-4-tert-butylphenol [H3(Me-L)] and 2,6-bis(4-methyl-6-tert-butylsalicyl)-4-tert-butylphenol [H3(tBu-L)] are described. The chloride complex [Nb(Me-L)Cl2]2 (1) was prepared in high yield by reaction of NbCl5 with H3(Me-L) in toluene. In contrast, the analogous reaction with H3(tBu-L) gave a mixture of [Nb(tBu-L)Cl2]2 (2) and [Nb(de-tBu-L)Cl2]2 (3a). During the formation of 3a, one of tert-butyl groups at the ortho position in the tBu-L ligand was lost. When the NbCl5/H3(tBu-L) reaction was carried out in acetonitrile, Nb[H(tBu-L)]Cl3(NCMe) (4) was obtained. Heating a solution of 4 in toluene generated 2 and 3a. The isolated complex 4 underwent ligand redistribution in acetonitrile to produce Nb[H(tBu-L)]2Cl(NCMe) (5). Treatment of NbCl5 with Li3(tBu-L) in toluene afforded 2. The chloride ligands in 1 and 2 smoothly reacted with 4 equiv of MeMgI and LiStBu, resulting in [Nb(R-L)Me2]2 [R = Me (6), tBu (7)] and Nb(Me-L)(StBu)2 (8), respectively. A number of the above complexes have been characterized by X-ray crystallography. In the structures of 1, 2, and 6, the R-L ligand is bound to the metal center with a U-coordination mode, while an alternative S-conformation is adopted for 3a and 8. Complexes 4 and 5 contain a bidentate H(tBu-L) diphenoxide-monophenol ligand. PMID:12425637

Matsuo, Tsukasa; Kawaguchi, Hiroyuki

2002-11-18

101

Symmetric Novikov superalgebras  

SciTech Connect

We study Novikov superalgebras with nondegenerate associative supersymmetric bilinear forms which are called symmetric Novikov superalgebras. We show that Novikov symmetric superalgebras are associative superalgebras with additional condition. Several examples of symmetric Novikov superalgebras are included, in particular, examples of symmetric Novikov superalgebras which are not 2-nilpotent. Finally, we introduce some notions of double extensions in order to give inductive descriptions of symmetric Novikov superalgebras.

Ayadi, Imen; Benayadi, Saied [Laboratoire de Mathematiques et Applications de Metz, CNRS-UMR 7122, Universite Paul Verlaine-Metz, Ile du Saulcy, F-57045 Metz Cedex 1 (France)

2010-02-15

102

Investigation on the linear and nonlinear optical properties of a metal organic complex—Bis thiourea zinc acetate single crystal  

NASA Astrophysics Data System (ADS)

The third order nonlinear optical properties of bis thiourea zinc acetate single crystal were measured using He-Ne laser (?=632.8nm) by employing the Z-scan technique. The magnitude of nonlinear refractive index and nonlinear absorption coefficient were found to be -2.11×10-8cm2/W and -1.201×10-3cm/W respectively. The linear refractive index of the complex was measured by the Brewster angle method and was found to be 1.483. The third order non-linear optical susceptibility ?(3) was found to be in the order of 10-6esu. The negative non-linear absorption coefficient shows the defocusing nature of the complex which is an essential property required for the application in optical limiting application. The second harmonic generation efficiency of the complex was studied using the Powder Kurtz method and was found to be 1.5 times greater than that of KDP.

Pabitha, G.; Dhanasekaran, R.

2013-09-01

103

Diffusion of the Linear CH3S-Au-SCH3 Complex on Au(111) from First Principles  

SciTech Connect

Recent experimental and computational advances have clearly established the importance of the linear alkylthiolate-Au-alkylthiolate (RS-Au-SR) complex at the interface between the thiolate groups and the gold surface. By using density functional theory-based first principles method, here we show that the elementary diffusion step of this linear complex on Au(111) has a barrier of only {approx}0.5 eV in the case of methylthiolate, indicating great mobility of the linear complex on Au(111). The role of this low barrier in the formation of a self-assembled monolayer of thiolate groups in the form of RS-Au-SR on Au(111) is discussed.

Jiang, Deen [ORNL; Dai, Sheng [ORNL

2009-01-01

104

Uranium-nitrogen multiple bonding: isostructural anionic, neutral, and cationic uranium nitride complexes featuring a linear U=N=U core.  

PubMed

Reaction of the uranium(III) tris(anilide) complex (THF)U(N[t-Bu]Ar)(3) (1, THF = tetrahydrofuran; Ar = 3,5-Me(2)C(6)H(3)) with MN(3) (M = Na, [N(n-Bu)(4)]) results in the formation of the bimetallic diuranium(IV/IV) complexes M[(mu-N)(U(N[t-Bu]Ar)(3))(2)] (M[3]), which feature a single nitride ligand engaged as a linear, symmetric bridge between two uranium centers. The stability of the U=N=U core across multiple charge states is illustrated by stepwise chemical oxidation of Na[3] to the diuranium(IV/V) complex (mu-N)(U(N[t-Bu]Ar)(3))(2) (3) and the diuranium(V/V) complex [(mu-N)(U(N[t-Bu]Ar)(3))(2)][B(Ar(F))(4)] {[3][B(Ar(F))(4)]; Ar(F) = 3,5-(CF(3))(2)C(6)H(3)}. M[3], 3, and [3][B(Ar(F))(4)] were characterized by NMR spectroscopy, single-crystal X-ray diffraction, and elemental analysis. The cyclic voltammogram of 3 reveals two clean, reversible one-electron electrochemical events at E(1/2) = -1.69 and -0.67 V, assigned to the [3](-)/3 and 3/[3](+) redox couples, respectively. The X-ray crystal structures of [N(n-Bu)(4)][3], 3, and [3][B(Ar(F))(4)] reveal a linear U=N=U core that contracts by only approximately 0.03 A across the [3](n) (n = -1, 0, +1) series, an effect that is rationalized as being primarily electrostatic in origin. [3][B(Ar(F))(4)] reacts with NaCN, eliminating Na[B(Ar(F))(4)] and forming the known diuranium(IV/IV) cyanoimide complex (mu-NCN)(U(N[t-Bu]Ar)(3))(2), suggesting that the U=N=U core has metallonitrene-like character. PMID:20178384

Fox, Alexander R; Arnold, Polly L; Cummins, Christopher C

2010-03-17

105

Pyramid diffraction in parity-time-symmetric optical lattices  

E-print Network

-symmetric systems can be realized by employing symmetric index guiding and an antisym- metric gain in the nonlinear regime for both focusing and defocusing nonlinearities. © 2013 Optical Society of America OCIS.38.001933 Parity-time (PT )-symmetric wave systems have the un- intuitive property that their linear

Yang, Jianke

106

Left-symmetric algebroids  

E-print Network

In this paper, we introduce a notion of a left-symmetric algebroid, which is a generalization of a left-symmetric algebra from a vector space to a vector bundle. The left multiplication gives rise to a representation of the corresponding sub-adjacent Lie algebroid. We construct left-symmetric algebroids from $\\mathcal O$-operators on Lie algebroids. We study phase spaces of Lie algebroids in terms of left-symmetric algebroids. Representations of left-symmetric algebroids are studied in detail. At last, we study deformations of left-symmetric algebroids, which could be controlled by the second cohomology class in the deformation cohomology.

Jiefeng Liu; Yunhe Sheng; Chengming Bai; Zhiqi Chen

2013-12-23

107

Symmetrical Bi-Aromatics  

Microsoft Academic Search

RECORDED instances of the preparation of symmetrically substituted bithienyls appear only scattered in the literature1. Furthermore, no work has been published concerning the symmetrically substituted 3,3'-bithienyls.

Louis J. Owen; F. F. Nord

1951-01-01

108

Prediction of rheometrical and complex flows of entangled linear polymers using the DCR model with chain stretch  

E-print Network

Tecchio, 80125 Napoli, Italy (November 16, 2005) Abstract We study the rheometrical and complex flow by Ianniruberto and Marrucci (2002) for entangled linear polymers. The single- and two-mode differential versions the rheometrical shear behavior of the fluid in the mod- est experimental range of deformation rates. Our

Wapperom, Peter

109

Pseudooctahedral Cobalt(III), Nickel(II), and Cadmium(II) Complexes of Linear, Sexadentate, Fluorinated Schiff Base Ligands.  

National Technical Information Service (NTIS)

New pseudooctahedral complexes, Ni(BTAT), Ni(BHAT), Cd(BTAT), C(BTAT)X, Co(BTAT)X. and (Co(BTAT))2CoY4 where X(-) = Br(-), I(-), NO3(-), and ClO4(-) and Y(-) = Cl(-) and SCN(-), have been prepared from the linear Schiff base ligands bis(trifluoroacetylace...

R. E. Sievers, S. C. Cummings

1971-01-01

110

Two-color hybridization with high complexity chromosome-specific probes and a degenerate alpha satellite probe DNA allows unambiguous discrimination between symmetrical and asymmetrical translocations  

Microsoft Academic Search

This report describes a fluorescence in situ hybridization approach to chromosome staining that facilitates detection of structural aberrations and allows discrimination between dicentric chromosomes and symmetrically translocated chromosomes. In this approach, selected whole chromosomes are stained in one color by hybridization with composite probes whose elements have DNA sequence homology along the length of the target chromosomes. In addition, all

Heinz-Ulrich G. Weier; Joe N. Lucas; Marilyn Poggensee; Richard Segraves; Daniel Pinkel; Joe W. Gray

1991-01-01

111

Modifications to Axially Symmetric Simulations Using New DSMC (2007) Algorithms  

NASA Technical Reports Server (NTRS)

Several modifications aimed at improving physical accuracy are proposed for solving axially symmetric problems building on the DSMC (2007) algorithms introduced by Bird. Originally developed to solve nonequilibrium, rarefied flows, the DSMC method is now regularly used to solve complex problems over a wide range of Knudsen numbers. These new algorithms include features such as nearest neighbor collisions excluding the previous collision partners, separate collision and sampling cells, automatically adaptive variable time steps, a modified no-time counter procedure for collisions, and discontinuous and event-driven physical processes. Axially symmetric solutions require radial weighting for the simulated molecules since the molecules near the axis represent fewer real molecules than those farther away from the axis due to the difference in volume of the cells. In the present methodology, these radial weighting factors are continuous, linear functions that vary with the radial position of each simulated molecule. It is shown that how one defines the number of tentative collisions greatly influences the mean collision time near the axis. The method by which the grid is treated for axially symmetric problems also plays an important role near the axis, especially for scalar pressure. A new method to treat how the molecules are traced through the grid is proposed to alleviate the decrease in scalar pressure at the axis near the surface. Also, a modification to the duplication buffer is proposed to vary the duplicated molecular velocities while retaining the molecular kinetic energy and axially symmetric nature of the problem.

Liechty, Derek S.

2008-01-01

112

Optimal symmetric flight studies  

NASA Technical Reports Server (NTRS)

Several topics in optimal symmetric flight of airbreathing vehicles are examined. In one study, an approximation scheme designed for onboard real-time energy management of climb-dash is developed and calculations for a high-performance aircraft presented. In another, a vehicle model intermediate in complexity between energy and point-mass models is explored and some quirks in optimal flight characteristics peculiar to the model uncovered. In yet another study, energy-modelling procedures are re-examined with a view to stretching the range of validity of zeroth-order approximation by special choice of state variables. In a final study, time-fuel tradeoffs in cruise-dash are examined for the consequences of nonconvexities appearing in the classical steady cruise-dash model. Two appendices provide retrospective looks at two early publications on energy modelling and related optimal control theory.

Weston, A. R.; Menon, P. K. A.; Bilimoria, K. D.; Cliff, E. M.; Kelley, H. J.

1985-01-01

113

A linear S-bridged trinuclear cobalt(III) complex with 2-aminobenzenethiol: Synthesis, crystal structure, and spectroscopic characterization  

PubMed Central

Treatment of cobalt(II) perchlorate hexahydrate with 2 molar equiv. of 2-aminobenzenethiol (Habt) in acetonitrile afforded a tricationic tricobalt complex, [Co{Co(abt)3}2](ClO4)3·2CH3CN, by aerial oxidation. The molecular structure of the meso (??) form of the complex was determined by X-ray crystallography. In the complex cation, the central Co is coordinated by six thiolate groups from two terminal fac(S)-[Co(abt)3] units in an octahedral geometry, forming a linear S-bridged tricobalt structure. PMID:24465064

PANJA, ANANGAMOHAN; MOORE, CURTIS E.; EICHHORN, DAVID M.

2013-01-01

114

Three Steps in One Pot: Synthesis of Linear Bilateral Extended 2,2':6',2?-Terpyridineruthenium(II) Complexes.  

PubMed

Metal complexes of linear bilateral extended 2,2':6',2?-terpyridine [2,6-bis(2-substituted furo[2,3-c]pyridin-5-yl)pyridine] are topological tridentate analogues of 5,5'-functionalized 2,2'-bipyridine. The present methodology provides access to linear bilateral extended 2,2':6',2?-terpyridineruthenium(II) complexes starting from 5,5?-bis(methoxymethoxy)-4,4?-bis(substituted ethynyl)-2,2':6',2?-terpyridines via one-pot cleavage of the methoxymethyl (MOM) protecting group, cycloisomerization, and metal complexation in the presence of Ru(DMSO)4Cl2. In this reaction, ruthenium(II) likely plays a triple role, acting as a Lewis acid to cleave the MOM ether, a catalyst facilitating 5-endo-dig cyclization, and a coordination metal center, being an integral part of the final product. PMID:25350686

Veliks, Janis; Blacque, Olivier; Siegel, Jay S

2014-11-17

115

Differential Dynamic Engagement within 24 SH3 Domain: Peptide Complexes Revealed by Co-Linear Chemical Shift Perturbation Analysis  

PubMed Central

There is increasing evidence for the functional importance of multiple dynamically populated states within single proteins. However, peptide binding by protein-protein interaction domains, such as the SH3 domain, has generally been considered to involve the full engagement of peptide to the binding surface with minimal dynamics and simple methods to determine dynamics at the binding surface for multiple related complexes have not been described. We have used NMR spectroscopy combined with isothermal titration calorimetry to comprehensively examine the extent of engagement to the yeast Abp1p SH3 domain for 24 different peptides. Over one quarter of the domain residues display co-linear chemical shift perturbation (CCSP) behavior, in which the position of a given chemical shift in a complex is co-linear with the same chemical shift in the other complexes, providing evidence that each complex exists as a unique dynamic rapidly inter-converting ensemble. The extent the specificity determining sub-surface of AbpSH3 is engaged as judged by CCSP analysis correlates with structural and thermodynamic measurements as well as with functional data, revealing the basis for significant structural and functional diversity amongst the related complexes. Thus, CCSP analysis can distinguish peptide complexes that may appear identical in terms of general structure and percent peptide occupancy but have significant local binding differences across the interface, affecting their ability to transmit conformational change across the domain and resulting in functional differences. PMID:23251481

Stollar, Elliott J.; Lin, Hong; Davidson, Alan R.; Forman-Kay, Julie D.

2012-01-01

116

Crystal Structure of a Symmetric Football-Shaped GroEL:GroES2-ATP14 Complex Determined at 3.8Å Reveals Rearrangement between Two GroEL Rings.  

PubMed

The chaperonin GroEL is an essential chaperone that assists in protein folding with the aid of GroES and ATP. GroEL forms a double-ring structure, and both rings can bind GroES in the presence of ATP. Recent progress on the GroEL mechanism has revealed the importance of a symmetric 1:2 GroEL:GroES2 complex (the "football"-shaped complex) as a critical intermediate during the functional GroEL cycle. We determined the crystal structure of the football GroEL:GroES2-ATP14 complex from Escherichia coli at 3.8Å, using a GroEL mutant that is extremely defective in ATP hydrolysis. The overall structure of the football complex resembled the GroES-bound GroEL ring of the asymmetric 1:1 GroEL:GroES complex (the "bullet" complex). However, the two GroES-bound GroEL rings form a modified interface by an ~7° rotation about the 7-fold axis. As a result, the inter-ring contacts between the two GroEL rings in the football complex differed from those in the bullet complex. The differences provide a structural basis for the apparently impaired inter-ring negative cooperativity observed in several biochemical analyses. PMID:25174333

Koike-Takeshita, Ayumi; Arakawa, Takatoshi; Taguchi, Hideki; Shimamura, Tatsuro

2014-10-23

117

Asymmetric Diels–Alder and ene reactions promoted by a Ti(IV) complex bearing a C 2-symmetric tridentate ligand 1 Dedicated to Professor K. K. Balasubramanian on the occasion of his 60th birthday 1  

Microsoft Academic Search

A new Ti(IV) complex obtained from the C2-symmetric amino diol (1R,5R)-3-aza-3-benzyl-1,5-diphenyl pentan-1,5-diol, (1R,5R)-1, is used effectively as a Lewis acid promoter in asymmetric Diels–Alder reactions. Using various Evans' oxazolidinones as dienophiles and cyclopentadiene as the diene high yields of the adducts with moderate enantioselectivity, under different reaction conditions are achieved. The effects of solvent, temperature and ligand on the enantioselectivity

G. Manickam; G. Sundararajan

1999-01-01

118

Normalized linear variance decay dimension density and its application of dynamical complexity detection in physiological (fMRI) time series  

NASA Astrophysics Data System (ADS)

The upper and lower bounds of the linear variance decay (LVD) dimension density are analytically deduced using multivariate series with uncorrelated and perfectly correlated component series. Then, the normalized LVD dimension density ( ?) is introduced. In order to measure the complexity of a scalar series with ?, a pseudo-multivariate series was constructed from the scalar time series using time-delay embedding. Thus, ? is used to characterize the complexity of the pseudo-multivariate series. The results from the model systems and fMRI data of anxiety subjects reveal that this method can be used to analyze short and noisy time series.

Xie, Xiaoping; Zhao, Xiaohu; Fang, Youtong; Cao, Zhitong; He, Guoguang

2011-04-01

119

Low complexity linear MMSE detector with recursive update algorithm for iterative detection-decoding MIMO OFDM system  

Microsoft Academic Search

Iterative turbo processing between detection and decoding shows near-capacity performance on a multiple-antenna system. Combining iterative processing with optimum front-end detection is particularly challenging because the front-end maximum a posteriori (MAP) algorithm has a computational complexity that is exponential in the throughput. Sub-optimum detector such as the soft interference cancellation linear minimum mean square error (SIC-LMMSE) detector with near front-end

Daniel N. Liu; Michael P. Fitz

2006-01-01

120

Non-linear resistance associated to complex geometry at high flow rates in vascular access for hemodialysis  

Microsoft Academic Search

\\u000a Successful maturation and long-term function of a vascular access for hemodialysis relies on the creation and maintenance\\u000a a low-resistance route between the arterial and the venous system. In this work, we demonstrate how vascular segments characterized\\u000a by complex geometry can be associated with non-linear resistance behavior at the sustained flow rates required for hemodialysis\\u000a treatment. Using an image-based computational hemodynamics

L. Antiga; R. N. Planken; K. Canneyt; L. Botti; A. Caroli; B. Ene-Iordache; J. Tordoir; P. Verdonck; A. Remuzzi

121

Quantization effects in the complex LMS adaptive algorithm: Linearization using dither-theory  

Microsoft Academic Search

This paper describes the use of dither to linearize the gradient quantizer in a digitally implemented LMS adaptive algorithm. When the LMS algorithm is implemented in a fixed-point digital processor, a choice must be made between rounding the gradient estimate before addition to the contents of the weight accumulator, or rounding the weight at the accumulator output and operating a

DOUGLAS T. SHERWOOD; NEIL J. BERSHAD

1987-01-01

122

Linear motif-mediated interactions have contributed to the evolution of modularity in complex protein interaction networks.  

PubMed

The modular architecture of protein-protein interaction (PPI) networks is evident in diverse species with a wide range of complexity. However, the molecular components that lead to the evolution of modularity in PPI networks have not been clearly identified. Here, we show that weak domain-linear motif interactions (DLIs) are more likely to connect different biological modules than strong domain-domain interactions (DDIs). This molecular division of labor is essential for the evolution of modularity in the complex PPI networks of diverse eukaryotic species. In particular, DLIs may compensate for the reduction in module boundaries that originate from increased connections between different modules in complex PPI networks. In addition, we show that the identification of biological modules can be greatly improved by including molecular characteristics of protein interactions. Our findings suggest that transient interactions have played a unique role in shaping the architecture and modularity of biological networks over the course of evolution. PMID:25299147

Kim, Inhae; Lee, Heetak; Han, Seong Kyu; Kim, Sanguk

2014-10-01

123

Linear Motif-Mediated Interactions Have Contributed to the Evolution of Modularity in Complex Protein Interaction Networks  

PubMed Central

The modular architecture of protein-protein interaction (PPI) networks is evident in diverse species with a wide range of complexity. However, the molecular components that lead to the evolution of modularity in PPI networks have not been clearly identified. Here, we show that weak domain-linear motif interactions (DLIs) are more likely to connect different biological modules than strong domain-domain interactions (DDIs). This molecular division of labor is essential for the evolution of modularity in the complex PPI networks of diverse eukaryotic species. In particular, DLIs may compensate for the reduction in module boundaries that originate from increased connections between different modules in complex PPI networks. In addition, we show that the identification of biological modules can be greatly improved by including molecular characteristics of protein interactions. Our findings suggest that transient interactions have played a unique role in shaping the architecture and modularity of biological networks over the course of evolution. PMID:25299147

Kim, Inhae; Lee, Heetak; Han, Seong Kyu; Kim, Sanguk

2014-01-01

124

Preparation of Linear ?-Conjugated Coordination Polymers Having Ruthenium(II) Complex in the Main Chain  

Microsoft Academic Search

Soluble p-conjugated coordination polymers having a ruthenium(II) complex in the main chain were prepared from a “soluble metal complex monomer” and a “bridging ligand” via coordination. Refluxing of an ethanol-water suspension containing (4,4'-dinonyl-2,2'-bipyridyl)Ru(III) with 2,3-bis(2'-pyridyl)pyrazine gave the coordination polymer. The resulting polymer was soluble in common organic solvents. The structure was confirmed by uv\\/vis spectra and gpc analysis.

Gen-ichi Konishi; Kensuke Naka; Yoshiki Chujo

1999-01-01

125

Main Vector Adaptation: A CMA Variant with Linear Time and Space Complexity  

Microsoft Academic Search

The covariance matrix adaptation (CMA)is one of the most powerful self adaptationmechanisms for Evolution Strategies.However, for increasing search space dimension N , the performance declines, since theCMA has space and time complexity O(N2).Adapting the main mutation vector insteadof the covariance matrix yields an adaptationmechanism with space and time complexityO(N ). Thus, the main vector adaptation(MVA) is appropriate for large-scale problemsin

Andreas Zell

2001-01-01

126

Direct synthesis of linear trinuclear M2IIMn complexes with acetate and NN donor ligands  

NASA Astrophysics Data System (ADS)

Two novel heterometallic complexes with general formula [M2Mn(OAc)6L2], where M = Cd (1), Cu (2) and L = 2,2'-bipyridyl (bpy) for (1), 1,10-phenanthroline (phen) for (2), were obtained using "direct synthesis" approach. Trinuclear molecular structure of the complexes was determined by single crystal X-ray analysis. EPR studies of 2 indicate that the coordination environment in Cu(II) equatorial plane remains unchanged in solution as compared to the initial compound. Due to low volatility of phen the products of its decomposition probably remain on the surface of metal oxides and, therefore, in contrary to previously studied bpy-containing complexes, the compounds with phen are not suitable precursors for binary oxides preparation.

Nahorna, Oksana V.; Makhankova, Valeria G.; Kokozay, Vladimir N.; Omelchenko, Iryna V.; Dyakonenko, Viktoriya V.; Shishkin, Oleg V.; Jezierska, Julia

2013-04-01

127

Structure of an antibody in complex with its mucin domain linear epitope that is protective against Ebola virus.  

PubMed

Antibody 14G7 is protective against lethal Ebola virus challenge and recognizes a distinct linear epitope in the prominent mucin-like domain of the Ebola virus glycoprotein GP. The structure of 14G7 in complex with its linear peptide epitope has now been determined to 2.8 Å. The structure shows that this GP sequence forms a tandem ?-hairpin structure that binds deeply into a cleft in the antibody-combining site. A key threonine at the apex of one turn is critical for antibody interaction and is conserved among all Ebola viruses. This work provides further insight into the mechanism of protection by antibodies that target the protruding, highly accessible mucin-like domain of Ebola virus and the structural framework for understanding and characterizing candidate immunotherapeutics. PMID:22171276

Olal, Daniel; Kuehne, Ana I; Bale, Shridhar; Halfmann, Peter; Hashiguchi, Takao; Fusco, Marnie L; Lee, Jeffrey E; King, Liam B; Kawaoka, Yoshihiro; Dye, John M; Saphire, Erica Ollmann

2012-03-01

128

Structure of an Antibody in Complex with Its Mucin Domain Linear Epitope That Is Protective against Ebola Virus  

PubMed Central

Antibody 14G7 is protective against lethal Ebola virus challenge and recognizes a distinct linear epitope in the prominent mucin-like domain of the Ebola virus glycoprotein GP. The structure of 14G7 in complex with its linear peptide epitope has now been determined to 2.8 Å. The structure shows that this GP sequence forms a tandem ?-hairpin structure that binds deeply into a cleft in the antibody-combining site. A key threonine at the apex of one turn is critical for antibody interaction and is conserved among all Ebola viruses. This work provides further insight into the mechanism of protection by antibodies that target the protruding, highly accessible mucin-like domain of Ebola virus and the structural framework for understanding and characterizing candidate immunotherapeutics. PMID:22171276

Olal, Daniel; Kuehne, Ana I.; Bale, Shridhar; Halfmann, Peter; Hashiguchi, Takao; Fusco, Marnie L.; Lee, Jeffrey E.; King, Liam B.; Kawaoka, Yoshihiro; Dye, John M.

2012-01-01

129

Prediction of rheometrical and complex flows of entangled linear polymers using the double-convection-  

E-print Network

found that the DCR model with stretch predicts the rheometrical shear behavior of the fluid well in simulations of complex flow reveal anomalous or questionable behavior, namely, shear thickening over in the modest experimental range of deformation rates. Our calculations for the higher shear rates reached

Keunings, Roland

130

PT-Symmetric Acoustics  

NASA Astrophysics Data System (ADS)

We introduce here the concept of acoustic parity-time (PT) symmetry and demonstrate the extraordinary scattering characteristics of the acoustic PT medium. On the basis of exact calculations, we show how an acoustic PT-symmetric medium can become unidirectionally transparent at given frequencies. Combining such a PT-symmetric medium with transformation acoustics, we design two-dimensional symmetric acoustic cloaks that are unidirectionally invisible in a prescribed direction. Our results open new possibilities for designing functional acoustic devices with directional responses.

Zhu, Xuefeng; Ramezani, Hamidreza; Shi, Chengzhi; Zhu, Jie; Zhang, Xiang

2014-07-01

131

Strongly degenerate homogeneous pseudo-Kähler structures of linear type and complex plane waves  

NASA Astrophysics Data System (ADS)

We study the class K2+K4 of homogeneous pseudo-Kähler structures in the strongly degenerate case. The local form and the holonomy of a pseudo-Kähler manifold admitting such a structure are obtained, leading to a possible complex generalization of homogeneous plane waves. The same question is tackled in the case of pseudo-hyper-Kähler and pseudo-quaternion Kähler manifolds.

Castrillón López, M.; Luján, I.

2013-11-01

132

Linear free energy relations and solvent effects for complexes of m-cresol and various bases  

SciTech Connect

The enthalpies, entropies, and equilibrium constants for the hydrogen bonded complexes of m-cresol with ten bases in cyclohexane solvent have been determined by calorimetric and spectroscopic methods. The logarithm of the equilibrium constant correlates well with the dipole moment of the base and the solvatochromic parameter {beta} which measures the electron donating ability of the base. The enthalpy and entropy data show that the dipole term does not enter into the log K correlation as a consequence of electrostatic interactions between acid and base in the complex. The free base-solvent interaction, which appears to be dipolar in origin, reduces the entropy of the free base and hence contributes to a favorable entropy change for complex formation. The present data are compared to previously reported data obtained in CCl{sub 4} solvent. Solvent effects on the thermodynamic parameters in CCl{sub 4} and cyclohexane appear to be related to dipolar interactions by m-cresol and the bases with the two solvents.

Spencer, J.N.; Allott, K.N.; Chanandin, S.; Enders, B.G.; Grushow, A.; Kneizys, S.P.; Mobley, D.; Naghdi, J.; Patti, L.M.; Salata, J.S. (Franklin and Marshall College, Lancaster, PA (USA))

1988-03-01

133

Minimal Residual Methods for Complex Symmetric, Skew Symmetric ...  

E-print Network

Apr 26, 2013 ... Foundation grant SES-0951576 through the Center for Robust Decision Making on Climate and ..... If A is changed to A ? ?I for some scalar shift ?, Tk becomes Tk ? ?I and ...... [26] P. C. Hansen and D. P. O'Leary. The use of ...

Sou-Cheng (Terrya) Choi

2013-04-26

134

Creating a Symmetrical Design  

NSDL National Science Digital Library

This unit teaches students the meaning of symmetry by having them manipulate a variety of objects. Using this knowledge, they will create a symmetrical design and write an informative paragraph about the quilt design and the importance of symmetry.

Service, National S.

2009-04-24

135

Complexation Between Weakly Basic Dendrimers and Linear Polyelectrolytes: Effects of Chain Stiffness, Grafts, and pOH  

NASA Astrophysics Data System (ADS)

The unique architecture and high charge density of dendrimer molecules have attracted interest for their utilization in gene delivery applications. The strong binding affinity of cationic dendrimers to genetic materials make them effective gene delivery vectors not only by shielding the nucleic acid (NA) material from degradative enzymes in the blood stream, but also by reducing the overall negative charge of the dendrimer-NA material complex, which in turn creates more favorable interaction with the anionic cell membrane. However, the high cytotoxicities of cationic dendrimers have motivated the development of polyethylene glycol (PEG) conjugated dendrimer molecules, which have been shown to reduce dendrimer cytotoxicity while still retaining transfection ability. In order to gain insight into how the addition of neutral grafts affects the binding affinity and conformations of dendrimer-NA material complexes, we have developed and numerically solved a Self-Consistent Field Theory approach for both grafted and non-grafted annealed charged dendrimer molecules in the presence of linear polyelectrolyte molecules. Specifically, this work examines the effect of linear polyelectrolyte stiffness, grafting chain length, and solution pOH.

Lewis, Thomas; Pandav, Gunja; Omar, Ahmad; Ganesan, Venkat

2013-03-01

136

In vitro cytotoxicity studies of palladacyclic complexes containing the symmetric diphosphine bridging ligand. Studies of their interactions with DNA and BSA.  

PubMed

The reactions between [Pd2{(C,N)-C6H4CH2NH(Et)}2(?-X)2] (X = Cl or Br) and 1,2-bis(diphenylphosphino)ethane (dppe) in the 1:1 molar ratio resulted in the dppe-bridged Pd(II) complexes, [Pd2{(C,N)-C6H4CH2NH(Et)}2(?-dppe)(Cl)2] (1) and [Pd2{(C,N)-C6H4CH2NH(Et)}2(?-dppe)(Br)2] (2), respectively, which were characterized by elemental analyses, infrared (IR), (1)H- and (31)P{(1)H} NMR spectroscopy. The molecular structure of 1 was determined by single-crystal X-ray diffraction. In vitro cytotoxicity of 1, 2, dppe, PhCH2NH(Et) and cisplatin were carried out against four human tumor cell lines. The interactions of complexes towards DNA and protein are investigated. The results suggested that both complexes could interact with FS-DNA through the intercalation mode. Moreover, the reactivity towards BSA revealed that the microenvironment and the secondary structure of BSA were changed in the presence of Pd(II) complexes. PMID:24374348

Karami, Kazem; Hosseini-Kharat, Mahboubeh; Sadeghi-Aliabadi, Hojjat; Lipkowski, Janusz; Mirian, Mina

2014-02-12

137

Linear free energy relationships for metal-ligand complexation: Bidentate binding to negatively-charged oxygen donor atoms  

NASA Astrophysics Data System (ADS)

Stability constants for metal complexation to bidentate ligands containing negatively-charged oxygen donor atoms can be estimated from the following linear free energy relationship (LFER): log KML = ?OO( ?O log KHL,1 + ?O log KHL,2) where KML is the metal-ligand stability constant for a 1:1 complex, KHL,1 and KHL,2 are the proton-ligand stability constants (the ligand p Ka values), and ?O is the Irving-Rossotti slope. The parameter ?OO is metal specific and has slightly different values for five and six membered chelate rings. LFERs are presented for 21 different metal ions and are accurate to within approximately 0.30 log units in predictions of log KML values. Ligands selected for use in LFER development include dicarboxylic acids, carboxyphenols, and ortho-diphenols. For ortho-hydroxybenzaldehydes, ?-hydroxycarboxylic acids, and ?-ketocarboxylic acids, a modification of the LFER where log KHL,2 is set equal to zero is required. The chemical interpretation of ?OO is that it accounts for the extra stability afforded to metal complexes by the chelate effect. Cu-NOM binding constants calculated from the bidentate LFERs are similar in magnitude to those used in WHAM 6. This LFER can be used to make log KML predictions for small organic molecules. Since natural organic matter (NOM) contains many of the same functional groups (i.e. carboxylic acids, phenols, alcohols), the LFER log KML predictions shed light on the range of appropriate values for use in modeling metal partitioning in natural systems.

Carbonaro, Richard F.; Atalay, Yasemin B.; Di Toro, Dominic M.

2011-05-01

138

Different molecular complexity of linear-isomaltomegalosaccharides and ?-cyclodextrin on enhancing solubility of azo dye ethyl red: Towards dye biodegradation.  

PubMed

Intermolecular interaction of linear-type ?-(1?6)-glucosyl megalosaccharide rich (L-IMS) and water-insoluble anionic ethyl red was firstly characterized in a comparison with inclusion complexation by cyclodextrins (CDs) to overcome the problem of poor solubility and bioavailability. Phase solubility studies indicated an enhancement of 3- and 9-fold over the solubility in water upon the presence of L-IMS and ?-CD, respectively. (1)H NMR and circular dichrosim spectra revealed the dye forms consisted of 1:1 stoichiometric inclusion complex within the ?-CD cavity, whereas they exhibited non-specific hydrophobic interaction, identified by solvent polarity changes, with L-IMS. The inclusion complex delivered by ?-CD showed an uncompetitive inhibitory-type effect to azoreductase, particularly with high water content that did not promote dye liberation. Addition of the solid dye dispersed into coupled-enzyme reaction system supplied by L-IMS as the dye solubilizer provided usual degradation rate. The dye intermission in series exhibited successful removal with at least 5 cycles was economically feasible. PMID:25087215

Lang, Weeranuch; Kumagai, Yuya; Sadahiro, Juri; Maneesan, Janjira; Okuyama, Masayuki; Mori, Haruhide; Sakairi, Nobuo; Kimura, Atsuo

2014-10-01

139

Cylindrically symmetric electrohydrodynamic patterning.  

PubMed

Cylindrically symmetric structures such as concentric rings and rosettes arise out of thin polymeric films subjected to strong electric fields. Experiments that formed concentric rings and theory capable of explaining these and other cylindrical structures are presented. These rings represent an additional member of a class of structures, including pillars and holes, formed by electrohydrodynamic patterning of thin films, occasionally referred to as lithographically induced self-assembly. Fabrication of a set of concentric rings begins by spin coating a thin poly(methyl methacrylate) film onto a silicon wafer. A mask is superimposed parallel to the film leaving a similarly thin air gap. Electric fields, acting in opposition to surface tension, destabilize the free interface when raised above the glass transition temperature. Central pillars nucleate under small cylindrical protrusions patterned on the mask. Rings then emerge sequentially, with larger systems having as many as 10 fully formed rings. Ring-to-ring spacings and annular widths, typically on the order of a micron, are approximately constant within a concentric cluster. The formation rate is proportional to the viscosity and, consequently, has the expected Williams-Landel-Ferry dependence on temperature. In light of these developments we have undertaken a linear stability analysis in cylindrical coordinates to describe these rings and ringlike structures. The salient feature of this analysis is the use of perturbations that incorporate their radial dependence in terms of Bessel functions as opposed to the traditional sinusoids of Cartesian coordinates. The theory predicts approximately constant ring-to-ring spacings, constant annular widths, and growth rates that agree with experiment. A secondary instability is observed at higher temperatures, which causes the rings to segment into arcs or pillar arrays. The cylindrical theory may be generalized to describe hexagonal pillar/hole packing, gratings, and rosettes with the first being of particular importance given the ubiquitous observation of hexagonal packing. The perturbation analysis presented here is relevant to any system with cylindrical symmetry, for which the radial dependence can be described in terms of Bessel functions. PMID:15600415

Deshpande, Paru; Pease, Leonard F; Chen, Lei; Chou, Stephen Y; Russel, William B

2004-10-01

140

Cylindrically symmetric electrohydrodynamic patterning  

NASA Astrophysics Data System (ADS)

Cylindrically symmetric structures such as concentric rings and rosettes arise out of thin polymeric films subjected to strong electric fields. Experiments that formed concentric rings and theory capable of explaining these and other cylindrical structures are presented. These rings represent an additional member of a class of structures, including pillars and holes, formed by electrohydrodynamic patterning of thin films, occasionally referred to as lithographically induced self-assembly. Fabrication of a set of concentric rings begins by spin coating a thin poly(methyl methacrylate) film onto a silicon wafer. A mask is superimposed parallel to the film leaving a similarly thin air gap. Electric fields, acting in opposition to surface tension, destabilize the free interface when raised above the glass transition temperature. Central pillars nucleate under small cylindrical protrusions patterned on the mask. Rings then emerge sequentially, with larger systems having as many as 10 fully formed rings. Ring-to-ring spacings and annular widths, typically on the order of a micron, are approximately constant within a concentric cluster. The formation rate is proportional to the viscosity and, consequently, has the expected Williams-Landel-Ferry dependence on temperature. In light of these developments we have undertaken a linear stability analysis in cylindrical coordinates to describe these rings and ringlike structures. The salient feature of this analysis is the use of perturbations that incorporate their radial dependence in terms of Bessel functions as opposed to the traditional sinusoids of Cartesian coordinates. The theory predicts approximately constant ring-to-ring spacings, constant annular widths, and growth rates that agree with experiment. A secondary instability is observed at higher temperatures, which causes the rings to segment into arcs or pillar arrays. The cylindrical theory may be generalized to describe hexagonal pillar/hole packing, gratings, and rosettes with the first being of particular importance given the ubiquitous observation of hexagonal packing. The perturbation analysis presented here is relevant to any system with cylindrical symmetry, for which the radial dependence can be described in terms of Bessel functions.

Deshpande, Paru; Pease, Leonard F., III; Chen, Lei; Chou, Stephen Y.; Russel, William B.

2004-10-01

141

The optical solitons in the Scarff parity-time symmetric potentials  

NASA Astrophysics Data System (ADS)

We investigate the existence and stability of solitons in parity-time (PT) symmetric Scarff complex potentials, including linear case, and self-focusing and self-defocusing nonlinear cases. For linear case, the PT-breaking points, the eigenvalues and eigenfunction for different modulated depths of PT symmetry Scarff complex potential are obtained numerically. For nonlinear cases, the existence and stability of fundamental and multipole solitons are studied in self-focusing and self-defocusing media. For a fixed modulated depth, the eigenvalue for fundamental or multipole linear modes is equal to the critical propagation constant bc of fundamental and multipole solitons existence. Fundamental solitons are stable in the self-defocusing nonlinear media and low power region for the self-focusing nonlinear case. Multipole solitons are stable with the propagation constants close to bc both for self-focusing and self-defocusing nonlinearities.

Chen, Haibo; Hu, Sumei; Qi, Lingmin

2014-11-01

142

Benchmarking of linear and nonlinear approaches for quantitative structure-property relationship studies of metal complexation with ionophores.  

PubMed

A benchmark of several popular methods, Associative Neural Networks (ANN), Support Vector Machines (SVM), k Nearest Neighbors (kNN), Maximal Margin Linear Programming (MMLP), Radial Basis Function Neural Network (RBFNN), and Multiple Linear Regression (MLR), is reported for quantitative-structure property relationships (QSPR) of stability constants logK1 for the 1:1 (M:L) and logbeta2 for 1:2 complexes of metal cations Ag+ and Eu3+ with diverse sets of organic molecules in water at 298 K and ionic strength 0.1 M. The methods were tested on three types of descriptors: molecular descriptors including E-state values, counts of atoms determined for E-state atom types, and substructural molecular fragments (SMF). Comparison of the models was performed using a 5-fold external cross-validation procedure. Robust statistical tests (bootstrap and Kolmogorov-Smirnov statistics) were employed to evaluate the significance of calculated models. The Wilcoxon signed-rank test was used to compare the performance of methods. Individual structure-complexation property models obtained with nonlinear methods demonstrated a significantly better performance than the models built using multilinear regression analysis (MLRA). However, the averaging of several MLRA models based on SMF descriptors provided as good of a prediction as the most efficient nonlinear techniques. Support Vector Machines and Associative Neural Networks contributed in the largest number of significant models. Models based on fragments (SMF descriptors and E-state counts) had higher prediction ability than those based on E-state indices. The use of SMF descriptors and E-state counts provided similar results, whereas E-state indices lead to less significant models. The current study illustrates the difficulties of quantitative comparison of different methods: conclusions based only on one data set without appropriate statistical tests could be wrong. PMID:16563012

Tetko, Igor V; Solov'ev, Vitaly P; Antonov, Alexey V; Yao, Xiaojun; Doucet, Jean Pierre; Fan, Botao; Hoonakker, Frank; Fourches, Denis; Jost, Piere; Lachiche, Nicolas; Varnek, Alexandre

2006-01-01

143

Braids, shuffles and symmetrizers  

NASA Astrophysics Data System (ADS)

Multiplicative analogues of the shuffle elements of the braid group rings are introduced; in local representations they give rise to certain graded associative algebras (b-shuffle algebras). For the Hecke and BMW algebras, the (anti)-symmetrizers have simple expressions in terms of the multiplicative shuffles. The (anti)-symmetrizers can be expressed in terms of the highest multiplicative 1-shuffles (for the Hecke and BMW algebras) and in terms of the highest additive 1-shuffles (for the Hecke algebras). The spectra and multiplicities of eigenvalues of the operators of the multiplication by the multiplicative and additive 1-shuffles are examined. Dedicated to the memory of Aleosha Zamolodchikov.

Isaev, A. P.; Ogievetsky, O. V.

2009-07-01

144

Infrared diode laser spectroscopy of the Kr-N2O van der Waals complex: the v1 symmetric stretch region of N2O  

Microsoft Academic Search

The rovibrational spectra of four isotopomers of the Kr–N2O van der Waals complex, namely Kr–N2O, Kr–N2O, Kr–N2O and Kr–N2O, were measured in the v1 vibrational band region of the N2O monomer (?1285?cm) using a tunable diode laser spectrometer to probe a pulsed supersonic slit jet. Rotational constants for both ground and excited vibrational states of these four isotopomers were accurately

Rui Zheng; Yu Zhu; Song Li; Chuanxi Duan

2011-01-01

145

Supramolecular solvatochromism. Effect of solvents on the self-assembly and charge transfer absorption characteristics of lipid-packaged, linear mixed-valence platinum complexes  

Microsoft Academic Search

Lipid-packaged, mixed-valence linear platinum complexes are dispersed in chloroform, chlorocyclohexane and in methylcyclohexane. They show indigo-colors, which are identical to solid samples. These lipid-complexes display supramolecular thermochromism, resulting from heat-induced dissociation and recovery of coordination chains. Unexpectedly, reassembled samples show altered CT absorption spectra. In chloroform, the reassembled complex gives indigo-color, while the chlorocyclohexane and methylcyclohexane dispersions show blue and

K. Kuroiwa; N. Oda; N. Kimizuka

2006-01-01

146

A Concrete Security Treatment of Symmetric Encryption  

Microsoft Academic Search

We study notions and schemes for symmetric (ie. private key) encryption in a concrete security framework. We give four different notions of security against chosen plaintext attack and analyze the concrete complexity of reductions among them, providing both upper and lower bounds, and obtaining tight relations. In this way we classify notions (even though polynomially reducible to each other) as

Mihir Bellare; Anand Desai; E. Jokipii; Phillip Rogaway

1997-01-01

147

Resonances for Symmetric Two-Barrier Potentials  

ERIC Educational Resources Information Center

We describe a method for the accurate calculation of bound-state and resonance energies for one-dimensional potentials. We calculate the shape resonances for symmetric two-barrier potentials and compare them with those coming from the Siegert approximation, the complex scaling method and the box-stabilization method. A comparison of the…

Fernandez, Francisco M.

2011-01-01

148

Symmetric differential capacitive pressure sensor  

NASA Astrophysics Data System (ADS)

Differential capacitive sensors are common to pressure gauges. Previous sensors of the bridge type have utilized only two variable (active) components, resulting in a half-bridge electrical equivalent circuit. There are numerous advantages of a symmetric full bridge, using four active components. The symmetry improves linearity and increases signal to noise ratio, especially when supported by electronics based on synchronous detection. Another advantage of symmetry is invariance to scaling, through immunity to stray capacitance. This feature is especially important in relationship to the current trend toward micro-electro-mechanical systems. A crude, inexpensive, macroscopic prototype of the present design was built with attention to high sensitivity. Constructed with a thin aluminized Mylar diaphragm, this device can readily resolve pressure changes smaller than 10-2 Pa.

Peters, Randall D.

1993-08-01

149

Symmetric and irregular aromatic silicon nanoclusters  

NASA Astrophysics Data System (ADS)

Based on first-principles calculations, we predict the existence of two classes of aromatic hydrogenated silicon nanoclusters. Despite their completely different structure, they both exhibit quite comparable physical and chemical properties due to the common presence of overcoordinated silicon atoms inducing extensive electron delocalization. Due to a complex interplay between strain relaxation and aromatic stabilization, apparently ill-defined nanoclusters might sometimes turn out to be more stable than their symmetric counterparts. Both symmetric and irregular aromatic silicon nanoclusters are extremely stable at ambient conditions and might readily find applications in future nano-technological devices.

Vach, Holger

2014-10-01

150

Symmetric Controller Design for Symmetric Plant Using Matrix Inequality Conditions  

Microsoft Academic Search

For symmetric systems, the useage of symmetric controllers is known to be effective. The existence conditions of the controller have been shown in several studies. They require the symmetry of the plant as well as the control specifications. This paper describes the condition by matrix inequalities and relaxes it to be applicable to the case of non-symmetric sepcifications for the

Tomoyuki Nagashio; Takashi Kida

2005-01-01

151

Symmetric modular torsatron  

DOEpatents

A fusion reactor device is provided in which the magnetic fields for plasma confinement in a toroidal configuration is produced by a plurality of symmetrical modular coils arranged to form a symmetric modular torsatron referred to as a symmotron. Each of the identical modular coils is helically deformed and comprise one field period of the torsatron. Helical segments of each coil are connected by means of toroidally directed windbacks which may also provide part of the vertical field required for positioning the plasma. The stray fields of the windback segments may be compensated by toroidal coils. A variety of magnetic confinement flux surface configurations may be produced by proper modulation of the winding pitch of the helical segments of the coils, as in a conventional torsatron, winding the helix on a noncircular cross section and varying the poloidal and radial location of the windbacks and the compensating toroidal ring coils.

Rome, J.A.; Harris, J.H.

1984-01-01

152

Control of linear modes in cylindrical resistive magnetohydrodynamics with a resistive wall, plasma rotation, and complex gain  

NASA Astrophysics Data System (ADS)

Feedback stabilization of magnetohydrodynamic (MHD) modes in a tokamak is studied in a cylindrical model with a resistive wall, plasma resistivity, viscosity, and toroidal rotation. The control is based on a linear combination of the normal and tangential components of the magnetic field just inside the resistive wall. The feedback includes complex gain, for both the normal and for the tangential components, and it is known that the imaginary part of the feedback for the former is equivalent to plasma rotation [J. M. Finn and L. Chacon, Phys. Plasmas 11, 1866 (2004)]. The work includes (1) analysis with a reduced resistive MHD model for a tokamak with finite ? and with stepfunction current density and pressure profiles, and (2) computations with a full compressible visco-resistive MHD model with smooth decreasing profiles of current density and pressure. The equilibria are stable for ? = 0 and the marginal stability values ?rp,rw < ?rp,iw < ?ip,rw < ?ip,iw (resistive plasma, resistive wall; resistive plasma, ideal wall; ideal plasma, resistive wall; and ideal plasma, ideal wall) are computed for both models. The main results are: (a) imaginary gain with normal sensors or plasma rotation stabilizes below ?rp,iw because rotation suppresses the diffusion of flux from the plasma out through the wall and, more surprisingly, (b) rotation or imaginary gain with normal sensors destabilizes above ?rp,iw because it prevents the feedback flux from entering the plasma through the resistive wall to form a virtual wall. A method of using complex gain Gi to optimize in the presence of rotation in this regime with ? > ?rp,iw is presented. The effect of imaginary gain with tangential sensors is more complicated but essentially destabilizes above and below ?rp,iw.

Brennan, D. P.; Finn, J. M.

2014-10-01

153

How much does inclusion of non-linearity and multi-point pattern recognition improve the spatial mapping of complex patterns of groundwater contamination?  

NASA Astrophysics Data System (ADS)

In this brief communication, we discuss the implication of the hypothesis that "non-linearity and multi-point pattern recognition can improve the spatial mapping of complex patterns of groundwater contamination". The discussion is based on our recently published work in Stochastic Environmental Research and Risk Assessment. Therein we have found that the use of a highly non-linear pattern learning technique in the form of an artificial neural network (ANN) can yield significantly superior results under the same set of constraints when compared to the more linear two-point ordinary kriging method.

Chowdhury, M.; Alouani, A.; Hossain, F.

2009-04-01

154

Symmetrical Bi-Aromatics  

Microsoft Academic Search

PREVIOUSLY reported work1 from this laboratory indicated the feasibility of condensing 2-halo-3-thenoic acids to form symmetrically substituted 2,2'-bithienyls. This provided the experimental basis for the continuation of our studies in the field of mixed bi-aromatics, wherein it was shown2 that an unsymmetrically substituted alpha-phenylthiophene actually exists in two stereoisomeric forms due to restricted rotation. In view of this fact, the

George N. Jean; Louis J. Owen; F. F. Nord

1952-01-01

155

Ejs Symmetric Top Model  

NSDL National Science Digital Library

The Ejs Symmetric Top model displays the motion of a top, in both the space frame and body frame, with no net toque applied. The top has an initial angular speed in the x, y, and z directions. The moments of inertia in each direction, and the initial angular positions and angular speeds can be changed via textboxes. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Symmetric Top model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ehu_rigid_bodies_symmetric.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for rigid body dynamics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Aguirregabiria, Juan

2008-08-18

156

Symmetrical reconfiguration of tensegrity structures  

Microsoft Academic Search

In this article we first present a mathematical model which describes the nonlinear dynamics of tensegrity structures. For certain tensegrity structures a particular class of motions, coined symmetrical motions, is defined. The corresponding equations of motion are derived and the conditions under which symmetrical motions occur are established. Reconfiguration procedures through symmetrical motions are proposed and examples are given.

Cornel Sultan; Martin Corless; Robert E. Skelton

2002-01-01

157

An application of the complex general linear model to analysis of fMRI single subjects multiple stimuli input data  

NASA Astrophysics Data System (ADS)

The general linear model (GLM) has been extensively applied to fMRI data in the time domain. However, traditionally time series data can be analyzed in the Fourier domain where the assumptions made as to the noise in the signal can be less restrictive and statistical tests are mathematically more rigorous. A complex form of the GLM in the Fourier domain has been applied to the analysis of fMRI (BOLD) data. This methodology has a number of advantages over temporal methods: 1. Noise in the fMRI data is modeled more generally and closer to that actually seen in the data. 2. Any input function is allowed regardless of the timing. 3. Non-parametric estimation of the transfer functions at each voxel are possible. 4. Rigorous statistical inference of single subjects is possible. This is demonstrated in the analysis of an experimental design with random exponentially distributed stimulus inputs (a two way ANOVA design with input stimuli images of alcohol, non-alcohol beverage and positive or negative images) sampled at 400 milliseconds. This methodology applied to a pair of subjects showed precise and interesting results (e.g. alcoholic beverage images attenuate the response of negative images in an alcoholic as compared to a control subject).

Rio, Daniel; Rawlings, Robert; Woltz, Lawrence; Gilman, Jodi; Hommer, Daniel

2009-02-01

158

Solution of the embedding problem and decomposition of symmetric matrices.  

PubMed Central

A solution of the problem of calculating cartesian coordinates from a matrix of interpoint distances (the embedding problem) is reported. An efficient and numerically stable algorithm for the transformation of distances to coordinates is then obtained. It is shown that the embedding problem is intimately related to the theory of symmetric matrices, since every symmetric matrix is related to a general distance matrix by a one-to-one transformation. Embedding of a distance matrix yields a decomposition of the associated symmetric matrix in the form of a sum over outer products of a linear independent system of coordinate vectors. It is shown that such a decomposition exists for every symmetric matrix and that it is numerically stable. From this decomposition, the rank and the numbers of positive, negative, and zero eigenvalues of the symmetric matrix are obtained directly. PMID:3857574

Sippl, M J; Scheraga, H A

1985-01-01

159

Plane Symmetric, Cylindrically Symmetric and Spherically Symmetric Black Solutions of Einstein Field Equations  

E-print Network

In this paper we present Plane symmetric, Cylindrically Symmetric and Spherically Symmetric Black hole or Vacuum solutions of Einstein Field Equations(EFEs). Some of these solutions are new which we have not seen in the literature. This calculation will help us in understanding the gravitational wave and gravitational wave spacetimes.

Farhad Ali

2014-10-19

160

An adaptive neural network-fuzzy linear regression approach for improved car ownership estimation and forecasting in complex and uncertain environments: the case of Iran  

Microsoft Academic Search

This paper applies a novel adaptive approach consisting of Artificial Neural Network (ANN) and Fuzzy Linear Regression (FLR) to improve car ownership forecasting in complex, ambiguous, and uncertain environments. This integrated approach is applied to forecast car ownership in Iran from 1930 to 2007. In this study, the level of car ownership is viewed as the result of demographic, politico-social,

A. Azadeh; N. Neshat; K. Rafiee; A. M. Zohrevand

2012-01-01

161

Linear optimal control of tokamak fusion devices  

SciTech Connect

The control of plasma position, shape and current in a tokamak fusion reactor is examined using linear optimal control. These advanced tokamaks are characterized by non up-down symmetric coils and structure, thick structure surrounding the plasma, eddy currents, shaped plasmas, superconducting coils, vertically unstable plasmas, and hybrid function coils providing ohmic heating, vertical field, radial field, and shaping field. Models of the electromagnetic environment in a tokamak are derived and used to construct control gains that are tested in nonlinear simulations with initial perturbations. The issues of applying linear optimal control to advanced tokamaks are addressed, including complex equilibrium control, choice of cost functional weights, the coil voltage limit, discrete control, and order reduction. Results indicate that the linear optimal control is a feasible technique for controlling advanced tokamaks where the more common classical control will be severely strained or will not work. 28 refs., 13 figs.

Kessel, C.E.; Firestone, M.A.; Conn, R.W.

1989-05-01

162

Linear-dendritic supramolecular complexes as nanoscale reaction vessels for "green" chemistry. Diels-Alder reactions between fullerene C60 and polycyclic aromatic hydrocarbons in aqueous medium.  

PubMed

This study describes the first Diels-Alder (DA) reaction performed in aqueous medium with highly hydrophobic compounds-fullerene (C 60) as the dienophile and anthracene (An) or tetracene (Tet) as the dienes, respectively. The reactions are performed in nanocontainers, constructed by self-assembly of linear-dendritic amphiphilic copolymers with poly(ethylene glycol), PEG or poly(ethylene oxide), PEO as the hydrophilic blocks and poly(benzyl ether) monodendrons as the hydrophobic fragments: G3PEO13k, dG3 and dG2. Comparative studies under identical conditions are carried out with an amphiphilic linear-linear copolymer, poly(styrene)1800- block-PEO2100, PSt-PEO, and the nonionic surfactant Igepal CO-720, IP720. The binding affinity of supermolecules built of these amphiphiles toward the DA reagents decreases in the following order: G3PEO13k > dG3 > PSt-PEO > dG2 > IP720. The kinetic constant of binding is evaluated for tetracene and decreases in a similar fashion: 5 x 10 (-7) M/min (G3PEO13k), through 4 x 10 (-7) M/min (PSt-PEO) down to 1.5 x 10 (-7) M/min for IP720. The mobility of substrates encapsulated in the micellar core, estimated by pyrene fluorescence decay, is 95-121 ns for the micelles of the linear-dendritic copolymers and notably higher for PSt-PEO (152 ns), revealing the much denser interior of the linear analogue. The apparent kinetic constant for the DA reaction of C 60 and Tet within the G3PEO13k supermolecule in aqueous medium is markedly higher than in organic solvent (toluene), 208 vs 1.82 M /min. With G3PEO13k the conversions reach 49% for the DA reaction between C 60 and An, and 55% for C 60 and Tet. Besides the monoadduct (26.5% yield) the reaction with An produces exclusively increasing amounts of D 2 h -symmetric antipodal bis-adduct, whose yield reaches up to 22.5% after 48 h. In addition to the environmentally friendly conditions notable advantages of the synthetic strategy described are the extended stability of the linear-dendritic nanovessels, the easy collection of the products formed, and the recovery and reuse of unreacted reagents and linear-dendritic copolymers. PMID:18781794

Simonyan, Arsen; Gitsov, Ivan

2008-10-21

163

Symmetrization for redundant channels  

NASA Technical Reports Server (NTRS)

A plurality of redundant channels in a system each contain a global image of all the configuration data bases in each of the channels in the system. Each global image is updated periodically from each of the other channels via cross channel data links. The global images of the local configuration data bases in each channel are separately symmetrized using a voting process to generate a system signal configuration data base which is not written into by any other routine and is available for indicating the status of the system within each channel. Equalization may be imposed on a suspect signal and a number of chances for that signal to heal itself are provided before excluding it from future votes. Reconfiguration is accomplished upon detecting a channel which is deemed invalid. A reset function is provided which permits an externally generated reset signal to permit a previously excluded channel to be reincluded within the system. The updating of global images and/or the symmetrization process may be accomplished at substantially the same time within a synchronized time frame common to all channels.

Tulplue, Bhalchandra R. (Inventor); Collins, Robert E. (Inventor)

1988-01-01

164

Novel Identification of Symmetric and Anti-Symmetric Quantum Functions  

E-print Network

Procedures are given below to construct symmetric and anti-symmetric quantum functions. If hidden in an oracle, such functions can be identified exactly, without iterative interrogation. This is another example of quantum search. The resulting positive (or negative) functions also serve to uniquely reorganize a superposition of states to give a basis state for testing purposes.

John Robert Burger

2003-08-28

165

Identifying Redundant Linear Constraints in Systems of Linear ...  

E-print Network

Jun 22, 2006 ... In semidefinite programming one optimizes a convex (often linear) objective ... Our methods extend certain redundancy techniques from linear programming ...... nation of the gradients of the other constraints binding at x? .... J. F. Sturm, “Using sedumi 1.02, a matlab toolbox for optimizing over symmetric ...

2006-06-22

166

Symmetric multilayer megampere X-pinch  

SciTech Connect

Raising the power of X-ray emission from an X-pinch by increasing the pinch current to the megampere level requires the corresponding increase in the initial linear mass of the load. This can be achieved by increasing either the number of wires or their diameter. In both cases, special measures should be undertaken to prevent the formation of a complicated configuration with an uncontrolled spatial structure in the region of wire crossing, because such a structure breaks the symmetry of the neck formed in the crossing region, destabilizes plasma formation, and degrades X-ray generation. To improve the symmetry of the wire crossing region, X-pinch configurations with a regular multilayer arrangement of wires in this region were proposed and implemented. The results of experiments with various symmetric X-pinch configurations on the COBRA facility at currents of {approx}1MA are presented. It is shown that an X-pinch with a symmetric crossing region consisting of several layers of wires made of different materials can be successfully used in megampere facilities. The most efficient combinations of wires in symmetric multilayer X-pinches are found in which only one hot spot forms and that are characterized by a high and stable soft X-ray yield.

Shelkovenko, T. A.; Pikuz, S. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); McBride, R. D. [Sandia National Laboratories (United States); Knapp, P. F.; Wilhelm, G. [Cornell University (United States); Sinars, D. B. [Sandia National Laboratories (United States); Hammer, D. A. [Cornell University (United States); Orlov, N. Yu. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2010-01-15

167

Symmetric multilayer megampere X-pinch  

NASA Astrophysics Data System (ADS)

Raising the power of X-ray emission from an X-pinch by increasing the pinch current to the megampere level requires the corresponding increase in the initial linear mass of the load. This can be achieved by increasing either the number of wires or their diameter. In both cases, special measures should be undertaken to prevent the formation of a complicated configuration with an uncontrolled spatial structure in the region of wire crossing, because such a structure breaks the symmetry of the neck formed in the crossing region, destabilizes plasma formation, and degrades X-ray generation. To improve the symmetry of the wire crossing region, X-pinch configurations with a regular multilayer arrangement of wires in this region were proposed and implemented. The results of experiments with various symmetric X-pinch configurations on the COBRA facility at currents of ˜1MA are presented. It is shown that an X-pinch with a symmetric crossing region consisting of several layers of wires made of different materials can be successfully used in megampere facilities. The most efficient combinations of wires in symmetric multilayer X-pinches are found in which only one hot spot forms and that are characterized by a high and stable soft X-ray yield.

Shelkovenko, T. A.; Pikuz, S. A.; McBride, R. D.; Knapp, P. F.; Wilhelm, G.; Sinars, D. B.; Hammer, D. A.; Orlov, N. Yu.

2010-01-01

168

Møller energy of the nonstatic spherically symmetric metrics  

E-print Network

The energy distribution in the most general nonstatic spherically symmetric space-time is obtained using M{\\o}ller's energy-momentum complex. This result is compared with the energy expression obtained by using the energy-momentum complex of Einstein. Some examples of energy distributions in different prescriptions are discussed.

S. S. Xulu

2000-10-19

169

Decay Structure for Symmetric Hyperbolic Systems with Non-Symmetric Relaxation and its Application  

NASA Astrophysics Data System (ADS)

This paper is concerned with the decay structure for linear symmetric hyperbolic systems with relaxation. When the relaxation matrix is symmetric, the dissipative structure of the systems is completely characterized by the Kawashima-Shizuta stability condition formulated in Umeda et al. (Jpn J Appl Math 1:435-457, 1984) and Shizuta and Kawashima (Hokkaido Math J 14:249-275, 1985) and we obtain the asymptotic stability result together with the explicit time-decay rate under that stability condition. However, some physical models which satisfy the stability condition have non-symmetric relaxation term (for example, the Timoshenko system and the Euler-Maxwell system). Moreover, it had been already known that the dissipative structure of such systems is weaker than the standard type and is of the regularity-loss type (see Duan in J Hyperbolic Differ Equ 8:375-413, 2011; Ide et al. in Math Models Meth Appl Sci 18:647-667, 2008; Ide and Kawashima in Math Models Meth Appl Sci 18:1001-1025, 2008; Ueda et al. in SIAM J Math Anal 2012; Ueda and Kawashima in Methods Appl Anal 2012). Therefore our purpose in this paper is to formulate a new structural condition which includes the Kawashima-Shizuta condition, and to analyze the weak dissipative structure for general systems with non-symmetric relaxation.

Ueda, Yoshihiro; Duan, Renjun; Kawashima, Shuichi

2012-07-01

170

Synthesis and spectral studies on metal complexes of s-triazine based ligand and non linear optical properties  

NASA Astrophysics Data System (ADS)

A series of transition metal complexes of type [ML] and [ML2]Cl2 (where M = Cu(II), Ni(II), Co(II) have synthesized from 2-phenylamino-4,6-dichloro-s-triazine and 3,5-dimethyl pyrazole; their characteristics have been investigated by means of elemental analyses, magnetic susceptibility, molar conductance, IR, UV-Vis, Mass, NMR and ESR spectra. The electrochemical behavior of copper(II) complexes we have studied, by using cyclic voltammetry. The ESR spectra of copper(II) complexes are recorded at 300 K and 77 K and their salient features are appropriately reported. Spectral datas, we found, show that the ligand acts as a neutral tridentate, and coordinates through the triazine ring nitrogen and pyrazolyl ring nitrogen atoms to the metal ion. Evident from our findings, the metal(II) complexes of [ML] type exhibit square pyramidal geometry, and that of [ML2]Cl2 exhibit octahedral geometry. The in vitro antimicrobial activities of the ligand and its complexes are evaluated against Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Proteus vulgaris, Cryptococcus neoformans, Pseudomonas aeruginosa, Salmonella typhi, Serratia marcescens, Shigella flexneri, Vibrio cholera, Vibris parahaemolyticus, Aspergillus niger, Candida albicans and Penicillium oxalicum by well-diffusion method. The second harmonic generation efficiency of the ligand and its complexes are determined and compared with urea and KDP.

Shanmugakala, R.; Tharmaraj, P.; Sheela, C. D.

2014-11-01

171

14 CFR 23.331 - Symmetrical flight conditions.  

Code of Federal Regulations, 2011 CFR

...conservative manner when determining the wing loads and linear inertia loads corresponding to any of the symmetrical flight conditions...due to maneuvering and gusts must be reacted by the angular inertia of the airplane in a rational or conservative manner....

2011-01-01

172

14 CFR 23.331 - Symmetrical flight conditions.  

Code of Federal Regulations, 2013 CFR

...conservative manner when determining the wing loads and linear inertia loads corresponding to any of the symmetrical flight conditions...due to maneuvering and gusts must be reacted by the angular inertia of the airplane in a rational or conservative manner....

2013-01-01

173

14 CFR 23.331 - Symmetrical flight conditions.  

Code of Federal Regulations, 2012 CFR

...conservative manner when determining the wing loads and linear inertia loads corresponding to any of the symmetrical flight conditions...due to maneuvering and gusts must be reacted by the angular inertia of the airplane in a rational or conservative manner....

2012-01-01

174

14 CFR 23.331 - Symmetrical flight conditions.  

Code of Federal Regulations, 2010 CFR

...conservative manner when determining the wing loads and linear inertia loads corresponding to any of the symmetrical flight conditions...due to maneuvering and gusts must be reacted by the angular inertia of the airplane in a rational or conservative manner....

2010-01-01

175

Axially symmetric motion of a rotating stratified fluid  

Microsoft Academic Search

The spherical modeling of geophysical fluid flow is examined. In particular the extension of some previous work done in spherical geometry to the specific case of interest in the Spacelab atmospheric circulation experiment is discussed. This involves changing the boundary conditions under which the basic equations are to be solved. For simplicity the linear, axially symmetric steady state solution is

B. J. Martin

1980-01-01

176

Diagonalization and simultaneous symmetrization of the gas-dynamic matrices  

NASA Technical Reports Server (NTRS)

The hyperbolic nature of the unsteady, inviscid, gas-dynamic equations implies the existence of a similarity transformation for diagonalizing an arbitrary linear combination of coefficient matrices. It is shown that the individual matrices are simultaneously symmetrized by the similarity transformation. The transformations and their norms can be applied to the well-posedness of the Cauchy problem, linear stability theory for finite-difference approximations, and simplification of block-tridiagonal systems that arise in implicit time-split algorithms.

Warming, R. F.; Beam, R. M.; Hyett, B. J.

1975-01-01

177

Self-assembly behavior of a linear-star supramolecular amphiphile based on host-guest complexation.  

PubMed

A star polymer, ?-cyclodextrin-poly(l-lactide) (?-CD-PLLA), and a linear polymer, azobenzene-poly(ethylene glycol) (Azo-PEG), could self-assemble into a supramolecular amphiphilic copolymer (?-CD-PLLA@Azo-PEG) based on the host-guest interaction between ?-CD and azobenzene moieties. This linear-star supramolecular amphiphilic copolymer further self-assembled into a variety of morphologies, including sphere-like micelle, carambola-like micelle, naan-like micelle, shuttle-like lamellae, tube-like fiber, and random curled-up lamellae, by tuning the length of hydrophilic or hydrophobic chains. The variation of morphology was closely related to the topological structure and block ratio of the supramolecular amphiphiles. These self-assembly structures could disassemble upon an ultraviolet (UV) light irradiation. PMID:25310380

Wang, Juan; Wang, Xing; Yang, Fei; Shen, Hong; You, Yezi; Wu, Decheng

2014-11-01

178

C2-symmetric inhibitors of Plasmodium falciparum plasmepsin II: synthesis and theoretical predictions.  

PubMed

A series of C(2)-symmetric compounds with a mannitol-based scaffold has been investigated, both theoretically and experimentally, as Plm II inhibitors. Four different stereoisomers with either benzyloxy or allyloxy P1/P1' side chains were studied. Computational ranking of the binding affinities of the eight compounds was carried out using the linear interaction energy (LIE) method relying on a complex previously determined by crystallography. Within both series of isomers the theoretical binding energies were in agreement with the enzymatic measurements, illustrating the power of the LIE method for the prediction of ligand affinities prior to synthesis. The structural models of the enzyme-inhibitor complexes obtained from the MD simulations provided a basis for interpretation of further structure-activity relationships. Hence, the affinity of a structurally similar ligand, but with a different P2/P2' substituent was examined using the same procedure. The predicted improvement in binding constant agreed well with experimental results. PMID:12901917

Ersmark, Karolina; Feierberg, Isabella; Bjelic, Sinisa; Hultén, Johan; Samuelsson, Bertil; Aqvist, Johan; Hallberg, Anders

2003-08-15

179

Symmetric States in Quantum Geometry  

Microsoft Academic Search

Symmetric states are defined in the kinematical sector of loop quantum\\u000agravity and applied to spherical symmetry and homogeneity. Consequences for the\\u000aphysics of black holes and cosmology are discussed.

M. Bojowaldand; H. A. Kastrup

2001-01-01

180

Computational design of a self-assembling symmetrical ?-propeller protein.  

PubMed

The modular structure of many protein families, such as ?-propeller proteins, strongly implies that duplication played an important role in their evolution, leading to highly symmetrical intermediate forms. Previous attempts to create perfectly symmetrical propeller proteins have failed, however. We have therefore developed a new and rapid computational approach to design such proteins. As a test case, we have created a sixfold symmetrical ?-propeller protein and experimentally validated the structure using X-ray crystallography. Each blade consists of 42 residues. Proteins carrying 2-10 identical blades were also expressed and purified. Two or three tandem blades assemble to recreate the highly stable sixfold symmetrical architecture, consistent with the duplication and fusion theory. The other proteins produce different monodisperse complexes, up to 42 blades (180 kDa) in size, which self-assemble according to simple symmetry rules. Our procedure is suitable for creating nano-building blocks from different protein templates of desired symmetry. PMID:25288768

Voet, Arnout R D; Noguchi, Hiroki; Addy, Christine; Simoncini, David; Terada, Daiki; Unzai, Satoru; Park, Sam-Yong; Zhang, Kam Y J; Tame, Jeremy R H

2014-10-21

181

hal-00252237,version1-12Feb2008 Symmetric form of governing equations  

E-print Network

hal-00252237,version1-12Feb2008 Symmetric form of governing equations for capillary fluids Sergey-linear systems of conservation laws can be symmetrized if they admit an additional convex conservation law. In particular, this implies the hyperbolicity of governing equations. For capillary fluids, the internal energy

Paris-Sud XI, Université de

182

On the Stability of Spherically Symmetric Configurations in Newtonian Limit of Jordan, Brans-Dicke Theory  

E-print Network

We discuss stability of spherically symmetric static solutions in Newtonian limit of Jordan, Brans-Dicke field equations. The behavior of the stable equilibrium solutions for the spherically symmetric configurations considered here, it emerges that the more compact a model is, the more stable it is. Moreover, linear stability analysis shows the existence of stable configurations for any polytropic index.

S. Kozyrev

2003-04-08

183

Dynamics of supercoiled and linear pTZ18U plasmids observed with a long-lifetime metal-ligand complex.  

PubMed

The metal-ligand complex, [Ru(bpy)2(dppz)]2+ (bpy = 2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazine) (Ru-BD), was used as a spectroscopic probe for studying nucleic acid dynamics. The Ru-BD complex displays a long lifetime of over 100 ns and a molecular light switch property upon DNA binding due to shielding of its dppz ligand from water. To further show the usefulness of this luminophore (Ru-BD) for probing DNA dynamics, we examined its intensity and anisotropy decays when intercalated into supercoiled and linear pTZ18U plasmids using frequency-domain fluorometry with a light-emitting diode (LED) as the modulated light source. Compared to the supercoiled plasmids with an average intensity decay time of 120.8 ns at 25 degrees C, we obtained somewhat longer lifetimes for the linear plasmids ((tau) = 141.4 ns at 25 degrees C), suggesting a more efficient shielding from water by the linear plasmids. The anisotropy decay data also showed longer rotational correlation times for the linear plasmids (495 and 35 ns at 25 degrees C) as compared to the supercoiled plasmids (412 and 27 ns at 25 degrees C). The slow and fast rotational correlation times appear to be consistent with the bending and torsional motions of the plasmids, respectively. The anisotropy values were quite similar, although the values of the supercoiled plasmids were slightly higher in both the steady-state and anisotropy decay measurements. These results indicate that Ru-BD can be applied in the study of both bending and torsional dynamics of nucleic acids. PMID:12073934

Kang, Jung Sook; Abugo, Omoefe O; Lakowicz, Joseph R

2002-01-01

184

The new WAsP flow model: a fast, linearized Mixed Spectral-Integration model applicable to complex terrain  

E-print Network

challenge for the wind energy industry is the prediction of the wind resource in complex terrain-up in certain areas, leading to a locally high wind resource. Currently missing, however, is a flow model, Roskilde, Denmark. *Communicating author. E-mail: jean-francois.corbett@risoe.dk Introduction A current

185

A new conformal duality of spherically symmetric space-times  

E-print Network

A contribution linear in r to the gravitational potential can be created by a suitable conformal duality transformation: the conformal factor is 1/(1+r)^2 and r will be replaced by r/(1+r), where r is the Schwarzschild radial coordinate. Thus, every spherically symmetric solution of conformal Weyl gravity is conformally related to an Einstein space. This result finally resolves a long controversy about this topic. As a byproduct, we present an example of a spherically symmetric Einstein space which is a limit of a sequence of Schwarzschild-de Sitter space-times but which fails to be expressable in Schwarzschild coordinates. This example also resolves a long controversy.

H. -J. Schmidt

1999-05-28

186

APPROXIMATING SYMMETRIC POSITIVE SEMIDEFINITE TENSORS OF EVEN ORDER*  

PubMed Central

Tensors of various orders can be used for modeling physical quantities such as strain and diffusion as well as curvature and other quantities of geometric origin. Depending on the physical properties of the modeled quantity, the estimated tensors are often required to satisfy the positivity constraint, which can be satisfied only with tensors of even order. Although the space P02m of 2mth-order symmetric positive semi-definite tensors is known to be a convex cone, enforcing positivity constraint directly on P02m is usually not straightforward computationally because there is no known analytic description of P02m for m > 1. In this paper, we propose a novel approach for enforcing the positivity constraint on even-order tensors by approximating the cone P02m for the cases 0 < m < 3, and presenting an explicit characterization of the approximation ?2m ? ?2m for m ? 1, using the subset ?2m?P02m of semi-definite tensors that can be written as a sum of squares of tensors of order m. Furthermore, we show that this approximation leads to a non-negative linear least-squares (NNLS) optimization problem with the complexity that equals the number of generators in ?2m. Finally, we experimentally validate the proposed approach and we present an application for computing 2mth-order diffusion tensors from Diffusion Weighted Magnetic Resonance Images. PMID:23285313

BARMPOUTIS, ANGELOS; JEFFREY, HO; VEMURI, BABA C.

2012-01-01

187

Reversible Switching between Nonquenched and Quenched States in Nanoscale Linear Arrays of Plant Light-Harvesting Antenna Complexes  

PubMed Central

A simple and robust nanolithographic method that allows sub-100 nm chemical patterning on a range of oxide surfaces was developed in order to fabricate nanoarrays of plant light-harvesting LHCII complexes. The site-specific immobilization and the preserved functionality of the LHCII complexes were confirmed by fluorescence emission spectroscopy. Nanopatterned LHCII trimers could be reversibly switched between fluorescent and quenched states by controlling the detergent concentration in the imaging buffer. A 3-fold quenching of the average fluorescence intensity was accompanied by a decrease in the average (amplitude-weighted) fluorescence lifetime from approximately 2.24 ns to approximately 0.4 ns, attributed to the intrinsic ability of LHCII to switch between fluorescent and quenched states upon changes in its conformational state. The nanopatterning methodology was extended by immobilizing a second protein, the enhanced green fluorescent protein (EGFP), onto LHCII-free areas of the chemically patterned surfaces. This very simple surface chemistry, which allows simultaneous selective immobilization and therefore sorting of the two types of protein molecules on the surface, is a key underpinning step toward the integration of LHCII into switchable biohybrid antenna constructs. PMID:24988144

2014-01-01

188

"Green" Synthesis of Unnatural Poly(Amino Acid)s with Zwitterionic Character and pH-Responsive Solution Behavior, Mediated by Linear-Dendritic Laccase Complexes.  

PubMed

This article describes the enzyme-catalyzed "green" synthesis of an unnatural poly(amino acid). dl-Tyrosine was polymerized under environmentally friendly conditions using linear-dendritic laccase complexes as initiators and water as solvent. The influence of the dendron generation in the linear-dendritic copolymers, the monomer concentration, and time and temperature on the polymer yields and molecular masses was investigated. Depending on the reaction conditions poly(tyrosine) with molecular mass (Mw) up to 82 kDa could be obtained in yields ranging between 45 and 69%. It was found that the linear-dendritic laccase complexes can induce further chain growth upon addition of fresh monomer to the preformed poly(tyrosine) in a fashion resembling the classic "living" polymerization. The structure of the poly(tyrosine) was investigated by NMR, FT-IR, and MALDI-TOF and it was discovered that the polymer chains consist of phenol repeating units linked together by C-C and C-O bonds randomly distributed along the backbone of the polymers. The materials formed are completely water-soluble and behave as typical poly(zwitterions) changing charge and size with the medium pH. DLS measurements reveal that the zeta potential of the polymers can vary between +15 mV at pH 1.2 with hydrodynamic diameter (Dh) = 6.7 nm to -35 mV at pH 11.8 and Dh = 10 nm. The isoelectric point was found at pH = 2.3-2.6, where Dh of the polymer is at the minimum (2.4 nm). PMID:25325886

Gitsov, Ivan; Wang, Lili; Vladimirov, Nikolay; Simonyan, Arsen; Kiemle, David J; Schutz, Andri

2014-11-10

189

Temporal linear mode complexity as a surrogate measure of the effect of remifentanil on the central nervous system in healthy volunteers  

PubMed Central

AIMS Previously, electroencephalographic approximate entropy (ApEn) effectively described both depression of central nervous system (CNS) activity and rebound during and after remifentanil infusion. ApEn is heavily dependent on the record length. Linear mode complexity, which is algorithmatically independent of the record length, was investigated to characterize the effect of remifentanil on the CNS using the combined effect and tolerance, feedback and sigmoid Emax models. METHODS The remifentanil blood concentrations and electroencephalographic data obtained in our previous study were used. With the recording of the electroencephalogram, remifentanil was infused at a rate of 1, 2, 3, 4, 5, 6, 7 or 8 µg kg?1 min?1 for 15–20 min. The areas below (AUCeffect) or above (AACrebound) the effect vs. time curve of temporal linear mode complexity (TLMC) and ApEn were calculated to quantitate the decrease of the CNS activity and rebound. The coefficients of variation (CV) of median baseline (E0), maximal (Emax), and individual median E0 minus Emaxvalues of TLMC were compared with those of ApEn. The concentration–TLMC relationship was characterized by population analysis using non-linear mixed effects modelling. RESULTS Median AUCeffectand AACreboundwere 1016 and 5.3 (TLMC), 787 and 4.5 (ApEn). The CVs of individual median E0 minus Emax were 35.6, 32.5% (TLMC, ApEn). The combined effect and tolerance model demonstrated the lowest Akaike information criteria value and the highest positive predictive value of rebound in tolerance. CONCLUSIONS The combined effect and tolerance model effectively characterized the time course of TLMC as a surrogate measure of the effect of remifentanil on the CNS. PMID:21223358

Choi, Byung-Moon; Shin, Da-Huin; Noh, Moon-Ho; Kim, Young-Hac; Jeong, Yong-Bo; Lee, Soo-Han; Lee, Eun-Kyung; Noh, Gyu-Jeong

2011-01-01

190

Plane symmetric thin-shell wormholes: Solutions and stability  

NASA Astrophysics Data System (ADS)

Using the cut-and-paste procedure, we construct static and dynamic, plane symmetric wormholes by surgically grafting together two spacetimes of plane symmetric vacuum solutions with a negative cosmological constant. These plane symmetric wormholes can be interpreted as domain walls connecting different universes, having planar topology, and upon compactification of one or two coordinates, cylindrical topology or toroidal topology, respectively. A stability analysis is carried out for the dynamic case by taking into account specific equations of state, and a linearized stability analysis around static solutions is also explored. It is found that thin-shell wormholes made of a dark energy fluid or of a cosmological constant fluid are stable, while thin-shell wormholes made of phantom energy are unstable.

Lemos, José P. S.; Lobo, Francisco S. N.

2008-08-01

191

Rotationally symmetric operators for surface interpolation  

SciTech Connect

The use of rotationally symmetric operators in vision is reviewed and conditions for rotational symmetry are derived for linear and quadratic forms in the first and second partial directional derivatives of a function f(x,y). Surface interpolation is considered to be the process of computing the most conservative solution consistent with boundary conditions. The 'most conservative' solution is modelled using the calculus of variations to find the minimum function that satisfies a given performance index. To guarantee the existence of a minimum function, Grimson has recently suggested that the performance index should be a seminorm. It is shown that all quadratic forms in the second partial derivatives of the surface satisfy this criterion. The seminorms that are, in addition, rotationally symmetric form a vector space whose basis is the square Laplacian and the quadratic variation. Whereas both seminorms give rise to the same Euler condition in the interior, the quadratic variation offers the tighter constraint at the boundary and is to be preferred for surface interpolation.

Brady, M.; Horn, B.K.P.

1982-01-01

192

Minimizing the symmetric difference distance in conic spline approximation  

E-print Network

Minimizing the symmetric difference distance in conic spline approximation Sunayana Ghosh and Gert Vegter Abstract. We show that the complexity (the number of elements) of an op- timal parabolic or conic of general conic arcs of varying type. The constants c1 and c2 are ex- pressed in the affine curvature

Vegter, Gert

193

Nonlinear Maximal Monotone Extensions of Symmetric Operators  

E-print Network

Given a linear semi-bounded symmetric operator $S\\ge -\\omega$, we explicitly define, and provide their nonlinear resolvents, nonlinear maximal monotone operators $A_\\Theta$ of type $\\lambda>\\omega$ (i.e. generators of one-parameter continuous nonlinear semi-groups of contractions of type $\\lambda$) which coincide with the Friedrichs extension of $S$ on a convex set $\\mathscr K$ containing ${\\mathscr D}(S)$. The extension parameter $\\Theta\\subset{\\mathfrak h}\\times{\\mathfrak h}$ ranges over the set of nonlinear maximal monotone relations on an auxiliary Hilbert space $\\mathfrak h$ isomorphic to the deficiency subspace of $S$. Moreover $A_\\Theta+\\lambda$ is a sub-potential operator (i.e. is the sub-differential of a lower semicontinuos convex function) whenever $\\Theta$ is sub-potential. Examples describing Laplacians with nonlinear singular perturbations supported on null sets and Laplacians with nonlinear boundary conditions on a bounded set are given.

Andrea Posilicano

2014-04-09

194

On the complex non-linear interaction between bacteria and redox dynamics in sediments and its effects on water quality  

NASA Astrophysics Data System (ADS)

Despite the fact that the prognoses on the availability of resources related to different climate scenarios have been already formulated, the complex hydrological and biogeochemical reactions taking place in different compartments in natural environmental media are poorly understood, especially regarding the interactions between water bodies, and the reactions taking place at soil-water interfaces. Amongst them, the inter-relationship between hydrology, chemistry and biology has important implications in natural (rivers, lakes) and man-made water facilities (lagoons, artificial recharge pounds, reservoirs, slow infiltration systems, etc). The consequences involve environment, economic, social and health-risk aspects. At the current stage, only limited explanations are available to understand the implications of these relationships on ecosystem services, water quality and water quantity. Therefore, there is an urgent need to seek a full understanding of these physical-biogeochemical processes in water-bodies, sediments and biota and its implications in ecological and health risk. We present a soil column experiment and a mathematical model which aim to study the mutual interplay between water and bacteria activity in porous media, the corresponding dynamics and the feedback on nutrient cycling by using a multidisciplinary approach.

Sanchez-Vila, X.; Rubol, S.; Fernandez-Garcia, D.

2011-12-01

195

Secure Symmetrical Multilevel Diversity Coding  

E-print Network

Secure symmetrical multilevel diversity coding (S-SMDC) is a source coding problem, where a total of L - N discrete memoryless sources (S1,...,S_L-N) are to be encoded by a total of L encoders. This thesis considers a natural generalization of SMDC...

Li, Shuo

2012-07-16

196

The symmetric strong moment problem  

Microsoft Academic Search

Sequences of polynomials that occur as denominators in the two point Paté table for two series expansions are considered in the special case when the series coefficients are solutions of a strong symmetric Stieltjes moment problem. The continued fractions whose convergents generate these polynomials as denominators are presented, together with determinant representations for the polynomials and the continued fraction coefficients.

A. K. Common; J. H. McCabe

1996-01-01

197

Simulation of Symmetrical Induction Machinery  

Microsoft Academic Search

The effectiveness of an analog computer in studying the performance of induction machinery is demonstrated with computer results which show the dynamic behavior of 2-phase and 3-phase machines during balanced and unbalanced operation. The computer simulation for these various modes of operation is conveniently obtained from the equations which describe the symmetrical induction machine in an arbitrary reference frame. Of

P. C. Krause; C. H. Thomas

1965-01-01

198

Method of Multiple Reference Frames Applied to the Analysis of Symmetrical Induction Machinery  

Microsoft Academic Search

A method of analyzing the constant-speed performance of a symmetrical induction machine with applied stator phase voltages of any periodic form is presented. Symmetrical components are not used in this analysis. Instead, it is shown that by employing a series of reference frames, dc circuit theory may be used to determine the performance of induction machines. Since phasor and complex

PAUL C. KRAUSE

1968-01-01

199

On the Energy-Momentum Densities of the Cylindrically Symmetric Gravitational Waves  

E-print Network

In this study, using Moller and Tolman prescriptions we calculate energy and momentum densities for the general cylindrically symmetric spacetime metric. We find that results are finite and well defined in these complexes. We also give the results for some cylindrically symmetric spacetime models.

Ali Havare; Mustafa Salti; Taylan Yetkin

2005-02-12

200

Quantitative phase reconstruction from input-output intensities using a shift-invariant linear imaging system  

SciTech Connect

We formulate an iteration scheme for quantitative two-dimensional phase retrieval of complex scalar wave fields from input-output intensity profiles using a coherent rotationally symmetric shift-invariant linear optical imaging system. This method is a generalization of our previous method for quantitative single-image pure phase reconstruction using an imperfect shift-invariant linear imaging system. The method is somewhat analogous to the Gerchberg-Saxton iterative phase-retrieval algorithm, but typically converges much more rapidly. We have demonstrated the efficacy of the method using simulated data in the presence of noise.

Yu, Rotha P.; Paganin, David M. [School of Physics, Monash University, Victoria 3800 (Australia)

2009-05-15

201

Absence of inflation symmetric commensurate states in inflation symmetric networks  

Microsoft Academic Search

In this paper we présent measurements of thé normal-to superconducting phase boundary T_c(H) for three différent networks possessing inflation symmetry. Fluxoid quantization constraints induce thé formation of a lattice of fluxoid quanta for any non-zéro perpendicular magnetic field, and at particular fields, T_c(H) exhibits cusp-like structure indicating that thé lattice is commensurate with thé underlying network geometry. For inflation symmetric

M. A. Itzler; R. Bojko; P. M. Chaikin

1994-01-01

202

Linear electric field mass spectrometry  

DOEpatents

A mass spectrometer and methods for mass spectrometry. The apparatus is compact and of low weight and has a low power requirement, making it suitable for use on a space satellite and as a portable detector for the presence of substances. High mass resolution measurements are made by timing ions moving through a gridless cylindrically symmetric linear electric field.

McComas, David J. (Los Alamos, NM); Nordholt, Jane E. (Los Alamos, NM)

1992-01-01

203

Linear electric field mass spectrometry  

DOEpatents

A mass spectrometer and methods for mass spectrometry are described. The apparatus is compact and of low weight and has a low power requirement, making it suitable for use on a space satellite and as a portable detector for the presence of substances. High mass resolution measurements are made by timing ions moving through a gridless cylindrically symmetric linear electric field. 8 figs.

McComas, D.J.; Nordholt, J.E.

1992-12-01

204

Nuclear physics with spherically symmetric supernova models  

E-print Network

Few years ago, Boltzmann neutrino transport led to a new and reliable generation of spherically symmetric models of stellar core collapse and postbounce evolution. After the failure to prove the principles of the supernova explosion mechanism, these sophisticated models continue to illuminate the close interaction between high-density matter under extreme conditions and the transport of leptons and energy in general relativistically curved space-time. We emphasize that very different input physics is likely to be relevant for the different evolutionary phases, e.g. nuclear structure for weak rates in collapse, the equation of state of bulk nuclear matter during bounce, multidimensional plasma dynamics in the postbounce evolution, and neutrino cross sections in the explosive nucleosynthesis. We illustrate the complexity of the dynamics using preliminary 3D MHD high-resolution simulations based on parameterized deleptonization. With established spherically symmetric models we show that typical features of the different phases are reflected in the predicted neutrino signal and that a consistent neutrino flux leads to electron fractions larger than 0.5 in neutrino-driven supernova ejecta.

M. Liebendoerfer; T. Fischer; C. Fröhlich; F. -K. Thielemann; S. Whitehouse

2007-08-31

205

Universal symmetric cloning: No-signalling and nonlinear quantum mechanics  

E-print Network

We present a pseudo-spin representation for universal symmetric 1-to-M cloning of qubits, including both linear and nonlinear evolutions. We derive a set of equations to be satisfied by the cloning transformation under the no-signalling condition, and find an expression for the fidelity. We further introduce the linearity constraint, and obtain the unique universal symmetric quantum cloning machine for "an arbitrary" fidelity. No-signalling condition alone leads to fidelities higher than those of the quantum machines, and the maximum value converges to 3/4 rather than the optimal quantum limit of 2/3. We introduce the "prime cloners" whose fidelities have multiplicative property and show that the infinite copy limit of the prime cloners is 1/2.

Gedik, Z

2012-01-01

206

Bounded symmetric homogeneous domains in infinite dimensional spaces  

Microsoft Academic Search

In this article, we exhibit a large class of Banach spaces whose open unit balls are bounded symmetric homogeneous domains. These Banach spaces, which we call J*-algebras, are linear spaces of operators mapping one Hilbert space into another and have a kind of Jordan tripte product structure. In particular, all Hilbert spaces and all B*--algebras are J*-algebras. Moreover, all four

Lawrence A. Harris

207

PT-symmetric phonon laser.  

PubMed

By exploiting recent developments associated with coupled microcavities, we introduce the concept of the PT-symmetric phonon laser with balanced gain and loss. This is accomplished by introducing gain to one of the microcavities such that it balances the passive loss of the other. In the vicinity of the gain-loss balance, a strong nonlinear relation emerges between the intracavity-photon intensity and the input power. This then leads to a giant enhancement of both optical pressure and mechanical gain, resulting in a highly efficient phonon-lasing action. These results provide a promising approach for manipulating optomechanical systems through PT-symmetric concepts. Potential applications range from enhancing mechanical cooling to designing phonon-laser amplifiers. PMID:25126921

Jing, Hui; Özdemir, S K; Lü, Xin-You; Zhang, Jing; Yang, Lan; Nori, Franco

2014-08-01

208

PT-Symmetric Phonon Laser  

E-print Network

By exploiting recent developments associated with coupled microcavities, we introduce the concept of PT-symmetric phonon laser with balanced gain and loss. This is accomplished by introducing gain to one of the microcavities such that it balances the passive loss of the other. In the vicinity of the gain-loss balance, a strong nonlinear relation emerges between the intracavity photon intensity and the input power. This then leads to a giant enhancement of both optical pressure and mechanical gain, resulting in a highly efficient phonon-lasing action. These results provide a promising approach for manipulating optomechanical systems through PT-symmetric concepts. Potential applications range from enhancing mechanical cooling to designing phonon-laser amplifiers.

H. Jing; Sahin K. Ozdemir; Xin-You Lv; Jing Zhang; Lan Yang; Franco Nori

2014-03-04

209

Symmetrization, quantum images and measurement  

E-print Network

We argue that symmetrization of an incoming microstate with similar states in a sea of microstates contained in a macroscopic detector can produce an effective image, which does not contradict the no-cloning theorem, and such a combinatorial set can then be used with first passage random walk interactions suggested in an earlier work to give the right quantum mechanical weight for measured eigenvalues.

Shafee, F

2005-01-01

210

Symmetrization, quantum images and measurement  

E-print Network

We argue that symmetrization of an incoming microstate with similar states in a sea of microstates contained in a macroscopic detector can produce an effective image, which does not contradict the no-cloning theorem, and such a combinatorial set can then be used with first passage random walk interactions suggested in an earlier work to give the right quantum mechanical weight for measured eigenvalues.

Fariel Shafee

2005-07-11

211

Spherically symmetric canonical quantum gravity  

E-print Network

Canonical quantization of spherically symmetric space-times is carried out, using real-valued densitized triads and extrinsic curvature components, with specific factor ordering choices. Comparison with previous work [1] reveals that the resulting physical Hilbert space has the same form, although the basic canonical variables are different in the two approaches. As an extension, holonomy modifications from Loop Quantum Gravity are shown to deform the Dirac space-time algebra, while going beyond 'effective' calculations.

Brahma, Suddhasattwa

2014-01-01

212

Greedy algorithm and symmetric matroids  

Microsoft Academic Search

Symmetric matroids are set systems which are obtained, in some sense, by a weakening of the structure of a matroid. These\\u000a set systems are characterized by a greedy algorithm and they are suitable for dealing with autodual properties of matroids.\\u000a Applications are given to the eulerian tours of 4-regular graphs and the theory ofg-matroids.

André Bouchet

1987-01-01

213

Skyrmions and vector mesons: a symmetric approach  

SciTech Connect

We propose an extension of the effective, low-energy chiral Lagrangian known as the Skyrme model, to one formulated by a non-linear sigma model generalized to include vector mesons in a symmetric way. The model is based on chiral SU(6) x SU(6) symmetry spontaneously broken to static SU(6). The rho and other vector mesons are dormant Goldstone bosons since they are in the same SU(6) multiplet as the pion and other pseudoscalars. Hence the manifold of our generalized non-linear sigma model is the coset space (SU(6) x SU(6))/Su(6). Relativistic effects, via a spin-dependent mass term, break the static SU(6) and give the vectors a mass. The model can then be fully relativistic and covariant. The lowest-lying Skyrmion in this model is the whole baryonic 56-plet, which splits into the octet and decuplet in the presence of relativistic SU(6)-breaking. Due to the built-in SU(6) and the presence of vector mesons, the model is expected to have better phenomenological results, as well as providing a conceptually more unified picture of mesons and baryons. 29 references.

Caldi, D.G.

1984-01-01

214

Modeling Symmetric Macromolecular Structures in Rosetta3  

PubMed Central

Symmetric protein assemblies play important roles in many biochemical processes. However, the large size of such systems is challenging for traditional structure modeling methods. This paper describes the implementation of a general framework for modeling arbitrary symmetric systems in Rosetta3. We describe the various types of symmetries relevant to the study of protein structure that may be modeled using Rosetta's symmetric framework. We then describe how this symmetric framework is efficiently implemented within Rosetta, which restricts the conformational search space by sampling only symmetric degrees of freedom, and explicitly simulates only a subset of the interacting monomers. Finally, we describe structure prediction and design applications that utilize the Rosetta3 symmetric modeling capabilities, and provide a guide to running simulations on symmetric systems. PMID:21731614

DiMaio, Frank; Leaver-Fay, Andrew; Bradley, Phil; Baker, David; Andre, Ingemar

2011-01-01

215

Mitochondrial respiratory rates and activities of respiratory chain complexes correlate linearly with heteroplasmy of deleted mtDNA without threshold and independently of deletion size.  

PubMed

To clarify the importance of deleted protein and tRNA genes on the impairment of mitochondrial function, we performed a quantitative analysis of biochemical, genetic and morphological findings in skeletal muscles of 16 patients with single deletions and 5 patients with multiple deletions of mtDNA. Clinically, all patients showed chronic progressive external ophthalmoplegia (CPEO). The size of deletions varied between 2.5 and 9 kb, and heteroplasmy between 31% and 94%. In patients with single deletions, the citrate synthase (CS) activity was nearly doubled. Decreased ratios of pyruvate- and succinate-dependent respiration were detected in fibers of all patients in comparison to controls. Inverse and linear correlations without thresholds were established between heteroplasmy and (i) CS referenced activities of the complexes of respiratory chain, (ii) CS referenced maximal respiratory rates, (iii) and cytochrome-c-oxidase (COX) negative fibers. In patients with single and multiple deletions, all respiratory chain complexes as well as the respiratory rates were decreased to a similar extent. All changes detected in patients with single deletions were independent of deletion size. In one patient, only genes of ND5, ND4L as well as tRNA(Leu(CUN)), tRNA(Ser(AGY)), and tRNA(His) were deleted. The pronounced decrease in COX activity in this patient points to the high pathological impact of these missing tRNA genes. The activity of nuclear encoded SDH was also significantly decreased in patients, but to a lesser extent. This is an indication of secondary disturbances of mitochondria at CPEO. In conclusion, we have shown that different deletions cause mitochondrial impairments of the same phenotype correlating with heteroplasmy. The missing threshold at the level of mitochondrial function seems to be characteristic for large-scale deletions were tRNA and protein genes are deleted. PMID:12351217

Gellerich, Frank Norbert; Deschauer, Marcus; Chen, Ying; Müller, Tobias; Neudecker, Stephan; Zierz, Stephan

2002-10-01

216

A linear fractional transformation is a mapping f : C ! C of the form where a; b; c; d are complex numbers with ad bc 6= 0. The linear fractional  

E-print Network

.e., the subgroup those matrices mapped to the identity transformation) con- sists of the diagonal matricesA linear fractional transformation is a mapping f : C ! C of the form f(z) = az + b cz + d where a- mations f; g; h (3) (identity) Setting e(z) = z (a linear fractional transformation with a = 1; d = 1; b

Perry, Peter A.

217

Entanglement preparation using symmetric multiports  

NASA Astrophysics Data System (ADS)

We investigate the entanglement produced by a multi-path interferometer that is composed of two symmetric multiports, with phase shifts applied to the output of the first multiport. Particular attention is paid to the case when we have a single photon entering the interferometer. For this situation we derive a simple condition that characterizes the types of entanglement that one can generate. We then show how one can use the results from the single-photon case to determine what kinds of multi-photon entangled states one can prepare using the interferometer.

Brougham, T.; Košt'ák, V.; Jex, I.; Andersson, E.; Kiss, T.

2011-01-01

218

Experimental demonstration of optimal universal asymmetric quantum cloning of polarization states of single photons by partial symmetrization  

E-print Network

Experimental demonstration of optimal universal asymmetric quantum cloning of polarization states asymmetric 12 quantum cloning machine for qubits encoded into polarization states of single photons. Our linear-optical machine performs asymmetric cloning by partially symmetrizing the input polarization state

Dusek, Miloslav

219

Linear and star-shaped polynuclear Ru(II) complexes of 2-(2'-pyridyl)benzimidazolyl derivatives: syntheses, photophysical properties and red light-emitting devices.  

PubMed

Two new star-shaped ligands with a 1,3,5-triphenylbenzene core, tmpb (1,3,5-tris[p-2-(2'-pyridyl)benzimidazolylphenyl]benzene), and a 2,4,6-tris(p-biphenyl)-1,3,5-triazine core, tmbt (2,4,6-tris[p-2-(2'-pyridyl)benzimidazolylbiphenyl]-1,3,5-triazine), have been synthesized. Their corresponding trinuclear Ru(II) complexes [Ru3(tmpb)(bpy)6](PF6)6 (3) and [Ru3(tmpt)(bpy)6](PF6)6 (4) have been obtained. Two dinuclear linear Ru(II) complexes with previously reported ligands bmb (1,4-bis[2-(2'-pyridyl)benzimidazolyl]benzene) and bmbp (4,4'-bis[2-(2'-pyridyl)benzimidazolyl]biphenyl) and formulae [Ru2(bmb)(bpy)4](PF6)4 (1) and [Ru2(bmbp)(bpy)4](PF6)4 (2) have also been synthesized. Photophysical and electrochemical properties of the new compounds have been investigated. All four compounds display a characteristic metal-to-ligand-charge transfer (MLCT) absorption band and emit a red light when excited at the maximum of the MLCT band with emission maximum at 624, 629, 623 and 625 nm, respectively in neat films at ambient temperature. The emission quantum efficiency of the four complexes in neat films was determined to be 0.15, 0.17, 0.04 and 0.05, respectively. Light emitting devices based on these four compounds were fabricated by spin-casting the compound as a neat film to an ITO substrate, followed by the deposition of an aluminium metal layer. All devices emit a deep red light and the device behavior resembles that of a light emitting electrochemical cell. The EL maximum of the devices 1, 2, 3, and 4 is at 637, 657, 678, and 655 nm, respectively. All four devices have a fast response time when a sufficiently high voltage is applied. The device based on 2 is the brightest with a maximum luminance of 133 cd m(-2) at 7 V. The performance of devices based on 1, 2, and 4 is in general much more efficient than the device based on [Ru(bpy)3](PF6)2, which was fabricated and evaluated under the same experimental conditions as for the devices based on 1-4. PMID:16568181

Jia, Wen-Li; Hu, Yu-Feng; Gao, Jun; Wang, Suning

2006-04-14

220

Conjugate linear filtering  

Microsoft Academic Search

Aspects of optimum filtering for complex valued random processes are presented. Ordinary linear filters are complemented with conjugate linear filters. It is found that the incorporation of conjugate linear filtering improves signal-to-noise ratio by a factor of two in matched filter receivers. For optimum least squares filtering the inclusion of conjugate processing reduces mean-square error by a factor as great

W. Brown; R. Crane

1969-01-01

221

Integrability properties of symmetric-space fields reduced from axially symmetric Einstein and Yang-Mills equations  

SciTech Connect

A gauge-covariant symmetric-space formulation and integrability properties are given for symmetric-space fields reduced from the stationary axially symmetric Einstein equation and static axially symmetric self-dual Yang-Mills equations.

Chau, L.; Chou, K.; Hou, B.; Song, X.

1986-09-15

222

Dust Static Spherically Symmetric Solution in $f(R)$ Gravity  

E-print Network

In this paper, we take dust matter and investigate static spherically symmetric solution of the field equations in metric f(R) gravity. The solution is found with constant Ricci scalar curvature and its energy distribution is evaluated by using Landau-Lifshitz energy-momentum complex. We also discuss the stability condition and constant scalar curvature condition for some specific popular choices of f(R) models in addition to their energy distribution.

Muhammad Sharif; Hafiza Rizwana Kausar

2011-02-21

223

Spectral studies, cyclic voltammetry and synthesis of cobalt(II) and ruthenium(III) complexes with symmetric and asymmetric ring containing membered N 2S 2, N 4, and N 5 donor macrocyclic ligands  

Microsoft Academic Search

Reaction of divalent cobalt(II) and trivalent ruthenium(III) salts (NO3, SCN and SO4) with macrocyclic ligands L1, L2 and L3 having N2S2, N4 and N5 core, have been designed and carry out. All these three macrocyclic ligands and their complexes were obtained in pure form. Their structures were investigated by using microanalytical analyses, IR, mass, magnetic moments, electronic and EPR spectral

Sulekh Chandra; Rajiv Kumar

2005-01-01

224

Linear lattice gauge theory  

NASA Astrophysics Data System (ADS)

Linear lattice gauge theory is based on link variables that are arbitrary complex or real N×N matrices, in distinction to the usual (non-linear) formulation with unitary or orthogonal matrices. For a large region in parameter space both formulations belong to the same universality class, such that the continuum limits of linear and non-linear lattice gauge theory are identical. We explore if the linear formulation can help to find a non-perturbative continuum limit formulated in terms of continuum fields. Linear lattice gauge theory exhibits excitations beyond the gauge fields. In the linear formulation the running gauge coupling corresponds to the flow of the minimum of a "link potential". This minimum occurs for a nonzero value of the link variable l0 in the perturbative regime, while l0 vanishes in the confinement regime. We discuss a flow equation for the scale-dependent location of the minimum l0(k).

Wetterich, C.

2014-07-01

225

Symmetry breaking of solitons in one-dimensional parity-time-symmetric optical potentials.  

PubMed

Symmetry breaking of solitons in a class of one-dimensional parity-time (PT) symmetric complex potentials with cubic nonlinearity is reported. In generic PT-symmetric potentials, such symmetry breaking is forbidden. However, in a special class of PT-symmetric potentials V(x)=g2(x)+?g(x)+ig'(x), where g(x) is a real and even function and ? a real constant, symmetry breaking of solitons can occur. That is, a branch of non-PT-symmetric solitons can bifurcate out from the base branch of PT-symmetric solitons when the base branch's power reaches a certain threshold. At the bifurcation point, the base branch changes stability, and the bifurcated branch can be stable. PMID:25360924

Yang, Jianke

2014-10-01

226

The power of symmetric extensions for entanglement detection  

E-print Network

In this paper, we present new progress on the study of the symmetric extension criterion for separability. First, we show that a perturbation of order O(1/N) is sufficient and, in general, necessary to destroy the entanglement of any state admitting an N Bose symmetric extension. On the other hand, the minimum amount of local noise necessary to induce separability on states arising from N Bose symmetric extensions with Positive Partial Transpose (PPT) decreases at least as fast as O(1/N^2). From these results, we derive upper bounds on the time and space complexity of the weak membership problem of separability when attacked via algorithms that search for PPT symmetric extensions. Finally, we show how to estimate the error we incur when we approximate the set of separable states by the set of (PPT) N -extendable quantum states in order to compute the maximum average fidelity in pure state estimation problems, the maximal output purity of quantum channels, and the geometric measure of entanglement.

Miguel Navascues; Masaki Owari; Martin B. Plenio

2009-06-15

227

The power of symmetric extensions for entanglement detection  

E-print Network

In this paper, we present new progress on the study of the symmetric extension criterion for separability. First, we show that a perturbation of order O(1/N) is sufficient and, in general, necessary to destroy the entanglement of any state admitting an N Bose symmetric extension. On the other hand, the minimum amount of local noise necessary to induce separability on states arising from N Bose symmetric extensions with Positive Partial Transpose (PPT) decreases at least as fast as O(1/N^2). From these results, we derive upper bounds on the time and space complexity of the weak membership problem of separability when attacked via algorithms that search for PPT symmetric extensions. Finally, we show how to estimate the error we incur when we approximate the set of separable states by the set of (PPT) N -extendable quantum states in order to compute the maximum average fidelity in pure state estimation problems, the maximal output purity of quantum channels, and the geometric measure of entanglement.

Navascues, Miguel; Plenio, Martin B

2009-01-01

228

Walking dynamics are symmetric (enough)  

E-print Network

Many biological phenomena, such as locomotion, circadian cycles, and breathing are quasi-periodic in nature and can be modeled as rhythmic dynamical systems. Dynamical systems modeling often involves neglecting certain characteristics of a physical system as a modeling convenience. For example, in the dynamics of locomotion, the musculoskeletal system is commonly treated as symmetric about the sagittal plane. Here we extend statistical cross validation techniques in order to examine the consequences of assuming (or not) bilateral symmetry. Indeed, we verify that there are statistically significant asymmetries in the dynamics of human walking, but nevertheless show that ignoring these asymmetries results in a more consistent and predictive model. In general, neglecting evident characteristics of a system can be more than a modeling convenience---it can produce a better model.

Ankaral?, M Mert; Madhav, Manu S; Long, Andrew; Bastian, Amy J; Cowan, Noah J

2014-01-01

229

Linear identities and commuting maps in rings with involution  

Microsoft Academic Search

Abstract. In this paper we extend Martindale's result by showing that the symmetric elements or the skew elements of a prime ring with involution of characteristic not 2 do not satisfy certain linear generalized polynomial identities. As applications, we determine the centralizing additive maps and the commuting traces of biadditive maps on the symmetric elements of a prime ring.

Pjek-Hwee Lee; Tsiu-Kwen Lee

1997-01-01

230

Critical binding and electron scattering by symmetric-top polar molecules.  

PubMed

Quantum treatments of electron interactions with polar symmetric-top rotor molecules show features not present in the treatment of the linear-polar-rotor model. For symmetric tops possessing non-zero angular momentum about the symmetry axis, a new critical dipole can be defined that guarantees an infinite set of dipole-bound states independent of the values of the components of the inertial tensor. Additionally, for this same class, the scattering cross section diverges for all nonzero values of dipole moments and inertial moments, similar to solutions for the fixed linear dipole. Additional predictions are presented for electron affinities and rotational resonances of these systems. PMID:25362310

Garrett, W R

2014-10-28

231

Efficient Complex Continuous-Time IIR Filter Design via Generalized Vector Fitting  

Microsoft Academic Search

We present a novel model identifica- tion technique for designing complex infinite-impulse- response (IIR) continuous-time filters through gen- eralizing the Vector Fitting (VF) algorithm, which is extensively used for continuous-time frequency- domain rational approximation to symmetric func- tions, to asymmetrical cases. VF involves a two- step pole refinement process based on a linear least- squares solve and an eigenvalue problem.

Chi-Un Lei; Chung-Man Cheung; Hing-Kit Kwan; Ngai Wong

2008-01-01

232

Bart Preneel An introduction to symmetric cryptography  

E-print Network

Bart Preneel An introduction to symmetric cryptography January 2003 1 An Introduction to Symmetric Cryptology Prof. Bart Preneel Katholieke Universiteit Leuven, Belgium Bart.Preneel@esat.kuleuven.ac.be http detectionresponse Data confidentiality Alice Bob Eve Entity authentication BobEve Hello, I am Alice #12;Bart Preneel

Bachoc, Christine

233

COMMUNICATION-AVOIDING SYMMETRIC-INDEFINITE FACTORIZATION  

E-print Network

COMMUNICATION-AVOIDING SYMMETRIC-INDEFINITE FACTORIZATION GREY BALLARD, DULCENEIA BECKER, JAMES and banded. The algorithm is the first symmetric-indefinite communication-avoiding factorization: it performs, communication-avoiding algorithms, Aasen's fac- torization AMS subject classifications. 65F05, 15A23, 65Y20 1

Dongarra, Jack

234

Continuity and Separation in Symmetric Topologies  

ERIC Educational Resources Information Center

In this note, it is shown that in a symmetric topological space, the pairs of sets separated by the topology determine the topology itself. It is then shown that when the codomain is symmetric, functions which separate only those pairs of sets that are already separated are continuous, generalizing a result found by M. Lynch.

Harris, J.; Lynch, M.

2007-01-01

235

CONVEX, ROTATIONALLY SYMMETRIC LIQUID BRIDGES BETWEEN SPHERES  

E-print Network

CONVEX, ROTATIONALLY SYMMETRIC LIQUID BRIDGES BETWEEN SPHERES Thomas I. Vogel Department of Mathematics Texas A&M University College Station, TX 77843 tvogel@math.tamu.edu A liquid bridge between two different contact an- gles: one for each ball). If we consider rotationally symmetric bridges, then the free

Vogel, Thomas

236

Higher Dimensional Spherically Symmetric Expanding Wormholes in Einstein's Gravity  

NASA Astrophysics Data System (ADS)

We present ( n+1)-dimensional expanding structures in a cosmological background. Due to the expansion of spacetime the throat of wormholes enlarge with time. These solutions are examined in the Einstein's framework. A general linear relation between diagonal elements of an anisotropic energy-momentum tensor is assumed and the spherically symmetric structures are obtained. Solutions include naked singularity and expanding wormholes in an open universe. The traversibility of wormhole solutions is explored and we find that they are basically traversable. Finally, we consider the corresponding energy-momentum tensor properties and specially take into account the standard energy conditions.

Ebrahimi, Esmaeil

2014-06-01

237

Linear Algebra  

NSDL National Science Digital Library

This course provides an introduction to linear algebra. Topics include vector spaces, systems of linear equations, bases, linear independence, matrices, determinants, eigenvalues, inner products, quadratic forms and more. The course includes assignments, exams and study materials. MIT presents OpenCourseWare as free educational material online. No registration or enrollment is required to use the materials.

Ciubotaru, Dan

2010-12-28

238

Linear Accelerators  

NASA Astrophysics Data System (ADS)

In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

Sidorin, Anatoly

2010-01-01

239

{\\cal CPT} -symmetric spin-orbit-coupled condensate  

NASA Astrophysics Data System (ADS)

We consider a mean-field model of a spin-orbit-coupled atomic system (Bose-Einstein condensate) accounting for pumping and removal of atoms from the two ground states. This model introduces a concept of charge-parity-time ({\\cal CPT}) -symmetric system with a complex potential featuring a purely real spectrum. The introduced spin-orbit-coupled BEC possesses properties such as control of the stability by the external trap, singular {\\cal CPT} symmetry phase breaking, the existence of stable nonlinear modes with nonzero currents in repulsive and attractive condensates, multiply re-entrant {\\cal CPT} -symmetric phase, splitting of nonlinear modes into sets of solitons (wave packets) moving with different velocities and in different directions in the condensate released from the trap.

Kartashov, Y. V.; Konotop, V. V.; Zezyulin, D. A.

2014-09-01

240

Entropic gravity versus gravitational pseudotensors in static spherically symmetric spacetimes  

NASA Astrophysics Data System (ADS)

We present some well-known energy-momentum complexes and evaluate the gravitational energy associated with static spherically symmetric spacetimes. In fact, the energy distribution of the aforementioned gravitational background that is contained in a two-sphere of radius r shows that a test particle situated at a finite distance r experiences the gravitational field of the effective gravitational mass. In addition, we apply Verlinde's entropic gravity to find the emergent gravitational energy on static spherically symmetric screens. In this setup, we find that the energy distribution in the prescription of Møller is similar to the energy derived from the emergent gravity, while other prescriptions give the different results. This result may confirm the argument of Lessner who argues that Møller's definition of energy is a powerful concept of energy in General Relativity.

Mehdipour, S. Hamid

2014-08-01

241

Entropic gravity versus gravitational pseudotensors in static spherically symmetric spacetimes  

E-print Network

We present some well-known energy-momentum complexes and evaluate the gravitational energy associated with static spherically symmetric spacetimes. In fact, the energy distribution of the aforementioned gravitational background that is contained in a two-sphere of radius $r$ shows that a test particle situated at a finite distance $r$ experiences the gravitational field of the effective gravitational mass. In addition, we apply Verlinde's entropic gravity to find the emergent gravitational energy on static spherically symmetric screens. In this setup, we find that the energy distribution in the prescription of M{\\o}ller is similar to the energy derived from the emergent gravity, while other prescriptions give the different results. This result may confirm the argument of Lessner who argues that M{\\o}ller's definition of energy is a powerful concept of energy in General Relativity.

S. Hamid Mehdipour

2014-04-15

242

Chirally symmetric but confining dense and cold matter  

E-print Network

The folklore tradition about the QCD phase diagram is that at the chiral restoration phase transition at finite density hadrons are deconfined and there appears the quark matter. We address this question within the only known exactly solvable confining and chirally symmetric model. It is postulated within this model that there exists linear Coulomb-like confining interaction. The chiral symmetry breaking and the quark Green function are obtained from the Schwinger-Dyson (gap) equation while the color-singlet meson spectrum results from the Bethe-Salpeter equation. We solve this model at T=0 and finite chemical potential $\\mu$ and obtain a clear chiral restoration phase transition at the critical value \\mu_{cr}. Below this value the spectrum is similar to the previously obtained one at \\mu = 0. At \\mu > \\mu_{cr} the quarks are still confined and the physical spectrum consists of bound states which are arranged into a complete set of exact chiral multiplets. This explicitly demonstrates that a chirally symmetric matter consisting of confined but chirally symmetric hadrons at finite chemical potential is also possible in QCD. If so, there must be nontrivial implications for astrophysics.

L. Ya. Glozman; R. F. Wagenbrunn

2007-09-19

243

Maximum-confidence discrimination among symmetric qudit states  

SciTech Connect

We study the maximum-confidence (MC) measurement strategy for discriminating among nonorthogonal symmetric qudit states. Restricting to linearly dependent and equally likely pure states, we find the optimal positive operator valued measure (POVM) that maximizes our confidence in identifying each state in the set and minimizes the probability of obtaining inconclusive results. The physical realization of this POVM is completely determined and it is shown that after an inconclusive outcome, the input states may be mapped into a new set of equiprobable symmetric states, restricted, however, to a subspace of the original qudit Hilbert space. By applying the MC measurement again onto this new set, we can still gain some information about the input states, although with less confidence than before. This leads us to introduce the concept of sequential maximum-confidence (SMC) measurements, where the optimized MC strategy is iterated in as many stages as allowed by the input set, until no further information can be extracted from an inconclusive result. Within each stage of this measurement our confidence in identifying the input states is the highest possible, although it decreases from one stage to the next. In addition, the more stages we accomplish within the maximum allowed, the higher will be the probability of correct identification. We will discuss an explicit example of the optimal SMC measurement applied in the discrimination among four symmetric qutrit states and propose an optical network to implement it.

Jimenez, O. [Departamento de Fisica, Facultad de Ciencias Basicas, Universidad de Antofagasta, Casilla 170, Antofagasta (Chile); Center for Optics and Photonics, Universidad de Concepcion, Casilla 4016, Concepcion (Chile); Solis-Prosser, M. A.; Delgado, A.; Neves, L. [Center for Optics and Photonics, Universidad de Concepcion, Casilla 4016, Concepcion (Chile); MSI-Nucleus on Advanced Optics, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile)

2011-12-15

244

Heat conduction of symmetric lattices.  

PubMed

Heat conduction of symmetric Frenkel-Kontorova (FK) lattices with a coupling displacement was investigated. Through simplifying the model, we derived analytical expression of thermal current of the system in the overdamped case. By means of numerical calculations, the results indicate that: (i) As the coupling displacement d equals to zero, temperature oscillations of the heat baths linked with the lattices can control magnitude and direction of the thermal current; (ii) Whether there is a temperature bias or not, the thermal current oscillates periodically with d, whose amplitudes become greater and greater; (iii) As d is not equal to zero, the thermal current monotonically both increases and decreases with temperature oscillation amplitude of the heat baths, dependent on values of d; (iv) The coupling displacement also induces nonmonotonic behaviors of the thermal current vs spring constant of the lattice and coupling strength of the lattices; (v) These dynamical behaviors come from interaction of the coupling displacement with periodic potential of the FK lattices. Our results have the implication that the coupling displacement plays a crucial role in the control of heat current. PMID:23848662

Nie, Linru; Yu, Lilong; Zheng, Zhigang; Shu, Changzheng

2013-06-01

245

Intermittency on catalysts: symmetric exclusion  

E-print Network

We continue our study of intermittency for the parabolic Anderson equation $\\partial u/\\partial t = \\kappa\\Delta u + \\xi u$, where $u\\colon \\Z^d\\times [0,\\infty)\\to\\R$, $\\kappa$ is the diffusion constant, $\\Delta$ is the discrete Laplacian, and $\\xi\\colon \\Z^d\\times [0,\\infty)\\to\\R$ is a space-time random medium. The solution of the equation describes the evolution of a ``reactant'' $u$ under the influence of a ``catalyst'' $\\xi$. In this paper we focus on the case where $\\xi$ is exclusion with a symmetric random walk transition kernel, starting from equilibrium with density $\\rho\\in (0,1)$. We consider the annealed Lyapunov exponents, i.e., the exponential growth rates of the successive moments of $u$. We show that these exponents are trivial when the random walk is recurrent, but display an interesting dependence on the diffusion constant $\\kappa$ when the random walk is transient, with qualitatively different behavior in different dimensions. Special attention is given to the asymptotics of the exponents for $\\kappa\\to\\infty$, which is controlled by moderate deviations of $\\xi$ requiring a delicate expansion argument. In G\\"artner and den Hollander \\cite{garhol04} the case where $\\xi$ is a Poisson field of independent (simple) random walks was studied. The two cases show interesting differences and similarities. Throughout the paper, a comparison of the two cases plays a crucial role.

J. Gaertner; F. den Hollander; G. Maillard

2006-05-24

246

Design of a vertical ultra-precision linear axis modular driven by dual linear motors  

NASA Astrophysics Data System (ADS)

Non-rotational symmetric surface machining requires at least three numerically controlled axes, so there exists a desperately need of an ultra-precision vertical linear axis for ultra-precision machine tools. Based on the above consideration, a vertical ultra-precision linear axis has been developed to satisfy the need for non-rotational symmetric surface ultra-precision machining. The paper discusses the design challenges of the vertical ultra-precision linear axis and presents the mechanical structure designed with dual linear motor drive. A guide component and a gravity compensation mechanism have been designed. Finite element models for the vertical ultra-precision were established to evaluate the dynamic performance of the vertical ultra-precision linear axis. Analysis results show that the configuration of the vertical ultra-precision linear axis is reasonable with good dynamic performance.

Qi, Enbing; Fang, Zhenyong; Sun, Tao; Wang, Bo

2014-08-01

247

Linear Equations  

NSDL National Science Digital Library

This unit is a full lesson on linear equations with many problems for students and notes to teachers embedded. It begins with a question which illustrates the eight points students most often do not understand in order to answer it correctly. The unit is divided into ten sections: Characteristics of Linear Equations, Tables of Values for Graphing, Using Intercepts for Graphing, Using Slope-Intercept Form with Graphs, Families of Linear Equations, Graphing Linear vs. Non-Linear Equations, Creating, Graphing and Using Linear Equations, Simple System of Equations, What Went Wrong? (in which students observe how another student incorrectly answered a question), and Exploring with a Graphing Calculator. This is an excellent unit, used whole or in its parts, for students beginning with linear equations.

Czajkowski, Katrine

1997-01-01

248

Linear systems on tropical curves  

Microsoft Academic Search

A tropical curve ? is a metric graph with possibly unbounded edges, and tropical rational functions are continuous piecewise\\u000a linear functions with integer slopes. We define the complete linear system |D| of a divisor D on a tropical curve ? analogously to the classical counterpart. We investigate the structure of |D| as a cell complex and show that linear systems

Christian Haase; Gregg Musiker; Josephine Yu

249

Riemann Zeta Function Expressed as the Difference of Two Symmetrized Factorials Whose Zeros All Have Real Part of 1/2  

E-print Network

In this paper, some new results are reported for the study of Riemann zeta function $\\zeta(s)$ in the critical strip $0expressed in a generalized Euler product only involving prime numbers. Particularly, some new absolutely convergent series representations of $\\zeta(s)$ based on binomial expansion are presented. The crucial progress is to find that $\\zeta(s)$ can be expressed as a linear combination of polynomials of infinite degree, whose consequences are shown in several aspects: (i) numerically it provides a scenario to construct very fast convergent algorithm to calculate $\\zeta(s)$; (ii) interestingly it shows that Lagrange interpolation using infinite number of integer Euler zeta functions reproduces the exact complex $\\zeta(s)$; (iii) surprisingly it demonstrates that alternating Riemann zeta function (or other entire functions removing the pole of zeta function) is admissible to Melzak combinatorial transform for polynomials. Applying the functional symmetry on $\\zeta(s)$ in the form of Melzak transform induces $\\zeta(s)$ being written as the difference of two symmetrized factorials whose zeros are proved to all have real part of 1/2. Furthermore, the two symmetrized factorials are proved to have interlacing between the two sequences of the imaginary part of their zeros on upper (or lower) half plane, which ensures the difference of the two symmetrized factorials [proportional to $\\zeta(s)$] attaining the same feature of zeros with real part of 1/2 to endorse Riemann hypothesis.

Wusheng Zhu

2012-08-06

250

Strong photon antibunching of symmetric and antisymmetric modes in weakly nonlinear photonic molecules  

NASA Astrophysics Data System (ADS)

We study the photon statistics of symmetric and antisymmetric modes in a photonic molecule consisting of two linearly coupled nonlinear cavity modes. Our calculations show that strong photon antibunching of both symmetric and antisymmetric modes can be obtained even when the nonlinearity in the photonic molecule is weak. The strong antibunching effect results from the destructive interference between different paths for two-photon excitation. Moreover, we find that the optimal frequency detunings for strong photon antibunching in the symmetric and antisymmetric modes are linearly dependent on the coupling strength between the cavity modes in the photonic molecule. This implies that the photonic molecules can be used to generate tunable single-photon sources by tuning the values of the coupling strength between the cavity modes with weak nonlinearity.

Xu, Xun-Wei; Li, Yong

2014-09-01

251

Nonlinearly PT-symmetric systems: Spontaneous symmetry breaking and transmission resonances  

SciTech Connect

We consider a class of PT-symmetric systems which include mutually matched nonlinear loss and gain (in other words, a class of PT-invariant Hamiltonians in which both the harmonic and anharmonic parts are non-Hermitian). For a basic system in the form of a dimer, symmetric and asymmetric eigenstates, including multistable ones, are found analytically. We demonstrate that, if coupled to a linear chain, such a nonlinear PT-symmetric dimer generates previously unexplored types of nonlinear Fano resonances, with completely suppressed or greatly amplified transmission, as well as a regime similar to the electromagnetically induced transparency. The implementation of the systems is possible in various media admitting controllable linear and nonlinear amplification of waves.

Miroshnichenko, Andrey E.; Kivshar, Yuri S. [Nonlinear Physics Centre, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Malomed, Boris A. [Department of Physical Electronics, Faculty of Engineering, Tel Aviv University, IL-69978 Tel Aviv (Israel)

2011-07-15

252

Symmetric diffeomorphic registration of fibre orientation distributions.  

PubMed

Registration of diffusion-weighted images is an important step in comparing white matter fibre bundles across subjects, or in the same subject at different time points. Using diffusion-weighted imaging, Spherical Deconvolution enables multiple fibre populations within a voxel to be resolved by computing the fibre orientation distribution (FOD). In this paper, we present a novel method that employs FODs for the registration of diffusion-weighted images. Registration was performed by optimising a symmetric diffeomorphic non-linear transformation model, using image metrics based on the mean squared difference, and cross-correlation of the FOD spherical harmonic coefficients. The proposed method was validated by recovering known displacement fields using FODs represented with maximum harmonic degrees (l(max)) of 2, 4 and 6. Results demonstrate a benefit in using FODs at l(max)=4 compared to l(max)=2. However, a decrease in registration accuracy was observed when l(max)=6 was used; this was likely caused by noise in higher harmonic degrees. We compared our proposed method to fractional anisotropy driven registration using an identical code base and parameters. FOD registration was observed to perform significantly better than FA in all experiments. The cross-correlation metric performed significantly better than the mean squared difference. Finally, we demonstrated the utility of this method by computing an unbiased group average FOD template that was used for probabilistic fibre tractography. This work suggests that using crossing fibre information aids in the alignment of white matter and could therefore benefit several methods for investigating population differences in white matter, including voxel based analysis, tensor based morphometry, atlas based segmentation and labelling, and group average fibre tractography. PMID:21316463

Raffelt, David; Tournier, J-Donald; Fripp, Jurgen; Crozier, Stuart; Connelly, Alan; Salvado, Olivier

2011-06-01

253

Plane symmetric analogue of NUT space  

E-print Network

In this article on the basis of a new definition of spacetime symmetry, which is in accordance with the symmetry of the curvature invariants, we investigate exact vacuum solutions of Einstein field equations corresponding to both static and stationary plane symmetric spacetimes using the concepts of the (1+3)-decomposition or threading formalism. Demanding the presence of a plane symmetric gravitomagnetic field we find a family of two parameter (m and l) solutions, every member of which being the plane symmetric analogue of NUT space.

Mohammad Nouri-Zonoz; Ali Reza Tavanfar

2001-05-24

254

Discussion: Time-Symmetric Quantum Counterfactuals  

E-print Network

There is a trend to consider counterfactuals as invariably time-asymmetric. Recently, this trend manifested itself in the controversy about validity of counterfactual application of a time-symmetric quantum probability rule. Kastner (2003) analyzed this controversy and concluded that there are time-symmetric quantum counterfactuals which are consistent, but they turn out to be trivial. I correct Kastner's misquotation of my defense of time-symmetric quantum counterfactuals and explain their non-trivial aspects, thus contesting the claim that counterfactuals have to be time-asymmetric.

Lev Vaidman

2014-01-24

255

Morphological behavior spanning the symmetric AB and ABC block copolymer states  

NASA Astrophysics Data System (ADS)

The phase behavior expressed between the symmetric AB and ABC copolymer states was investigated for triblock copolymer systems differing only in the linear sequence of the same three constituent blocks: polystyrene (PS), polyisoprene (PI), and polyethylene oxide (PEO). Ten poly(styrene-b-isoprene-b-ethylene oxide) (PS-PI-PEO) and thirteen poly(isoprene-b-styrene-b-ethylene oxide) (PI-PS-PEO) triblock copolymers distributed along the same compositional isopleth (fA = fB) were characterized using a combination of small angle x-ray scattering, transmission electron microscopy, rheology, and static birefringence measurements. Differences in phase behavior exhibited by these two series of molecules are explained in terms of contrasting thermodynamic relationships imposed by the specific connectivity of each system. Only a single morphology, albeit a previously unreported non-cubic network phase, was found to span the two- and three-domain lamellar regions bounding the symmetric states in the PI-PS-PEO system. Both the simplicity of behavior and the formation of a new morphology are discussed in terms of the primary interaction parameter symmetry (chiAB ˜ chi BC) and the lack of frustration (chiAC > chiAB and chiBC in these molecules. In direct contrast, the frustration condition (chiAC < chiBC and/or chiAB ) and primary interaction parameter asymmetry (chiBC > chi AB) inherent to the PS-PI-PEO molecules was found to generate behavior of comparatively greater complexity. In this case, four distinct morphologies were identified between the two lamellar states, including core-shell analogs of the cylinder and gyroid phases, and two tentatively assigned lamellar-like structures both possessing regions of A/C interfacial contact.

Bailey, Travis Slade

256

Symmetric-Galerkin BEM simulation of fracture with frictional contact  

NSDL National Science Digital Library

A symmetric-Galerkin boundary element framework for fracture analysis with frictional contact (crack friction) on the crack surfaces is presented. The algorithm employs a continuous interpolation on the crack surface (utilizing quadratic boundary elements) and enables the determination of two important quantities for the problem, namely the local normal tractions and sliding displacements on the crack surfaces. An effective iterative scheme for solving this non-linear boundary value problem is proposed. The results of test examples are compared with available analytical solutions or with those obtained from the displacement discontinuity method (DDM) using linear elements and internal collocation. The results demonstrate that the method works well for difficult kinked junction crack problems. Copyright 2003 John Wiley & Sons, Ltd.

Phan, A.-V.; Napier, J. A.; Gray, L. J.; Kaplan, T.

2003-04-09

257

The free-electron laser in a symmetrical confocal resonator  

NASA Technical Reports Server (NTRS)

A tapered wiggler is used in a FEL oscillator to improve the saturation efficiency. During signal buildup the tapered wiggler does not provide optimum phase synchronism between the electron beam and the electromagnetic wave, resulting in an appreciable loss in small-signal gain. This problem can be ameliorated by using a multicomponent wiggler, which is a combination of a uniform wiggler and a tapered section. During buildup, gain is primarily contributed by the linear element, and at high power levels the gain and efficiency are enhanced by the taper. Ideally, one would like to have the optical waist location near the linear section at small-signal levels and at near the tapered section at high power levels. Placing the FEL in a symmetrical confocal resonator approaches this desired effect automatically since it has the unique characteristic that a stable mode exists for all locations of the waist of a Gaussian beam along the axis of the interferometer.

Ozcan, Meric; Pantell, Richard H.

1993-01-01

258

A small sample model selection criterion based on Kullback's symmetric divergence  

Microsoft Academic Search

The Kullback information criterion (KIC) is a recently developed tool for statistical model selection. KIC serves as an asymptotically unbiased estimator of a variant (within a constant) of the Kullback symmetric divergence, known also as J-divergence between the generating model and the fitted candidate model. In this paper, a bias correction to KIC is derived for linear regression models. The

Abd-Krim Seghouane; Maïza Bekara

2004-01-01

259

The dynamics of a laminar flow in a symmetric channel with a sudden expansion  

Microsoft Academic Search

Bifurcation analysis, linear stability study, and direct numerical simulations of the dynamics of a two-dimensional, incompressible, and laminar flow in a symmetric long channel with a sudden expansion with right angles and with an expansion ratio D=d (d is the width of the channel inlet section and D is the width of the outlet section) are presented. The bifurcation analysis

T. H AWA; Z. R USAK

2001-01-01

260

A survey of spherically symmetric spacetimes  

NASA Astrophysics Data System (ADS)

We survey many of the important properties of spherically symmetric spacetimes as follows. We present several different ways of describing a spherically symmetric spacetime and the resulting metrics. We then focus our discussion on an especially useful form of the metric of a spherically symmetric spacetime in polar-areal coordinates and its properties. In particular, we show how the metric component functions chosen are extremely compatible with notions in Newtonian mechanics. We also show the monotonicity of the Hawking mass in these coordinates. As an example, we discuss how these coordinates and the metric can be used to solve the spherically symmetric Einstein-Klein-Gordon equations. We conclude with a brief mention of some applications of these properties.

Parry, Alan R.

2014-12-01

261

On Radially Symmetric Solutions to Conservation Laws  

Microsoft Academic Search

\\u000a Radially symmetric solutions to multi-dimensional systems of conservations laws are important in applications and computations,\\u000a as well as in the general theory of conservative systems. Notwithstanding their one-dimensional nature they are poorly understood.\\u000a In particular this is true for the Euler equations in gas-dynamics. After a short review of symmetric solutions to the Euler\\u000a system, we introduce a scalar model

Helge Kristian Jenssen

262

The Stark Effect in Linear Potentials  

ERIC Educational Resources Information Center

We examine the Stark effect (the second-order shifts in the energy spectrum due to an external constant force) for two one-dimensional model quantum mechanical systems described by linear potentials, the so-called quantum bouncer (defined by V(z) = Fz for z greater than 0 and V(z) = [infinity] for z less than 0) and the symmetric linear potential…

Robinett, R. W.

2010-01-01

263

Properties of internal solitary waves in a symmetric three-layer fluid  

NASA Astrophysics Data System (ADS)

Though all the natural media have smooth density stratifications (with the exception of special cases such as sea surface, inversion layer in the atmosphere), the scales of density variations can be different, and some of them can be considered as very sharp. Therefore for the description of internal wave propagation and interaction in the ocean and atmosphere the n-layer models are often used. In these models density profile is usually approximated by a piecewise-constant function. The advantage of the layered models is the finite number of parameters and relatively simple solutions of linear and weakly nonlinear problems. Layered models are also very popular in the laboratory experiments with stratified fluid. In this study we consider symmetric, continuously stratified, smoothed three-layer fluid bounded by rigid horizontal surface and bottom. Three-layer stratification is proved to be a proper approximation of sea water density profile in some basins in the World Ocean with specific hydrological conditions. Such a medium is interesting from the point of view of internal gravity wave dynamics, because in the symmetric case it leads to disappearing of quadratic nonlinearity when described in the framework of weakly nonlinear evolutionary models, that are derived through the asymptotic expansion in small parameters of nonlinearity and dispersion. The goal of our study is to determine the properties of localized stationary internal gravity waveforms (solitary waves) in this symmetric three-layer fluid. The investigation is carried out in the framework of improved mathematical model describing the transformation of internal wave fields generated by an initial disturbance. The model is based on the program complex for the numerical simulation of the two-dimensional (vertical plane) fully nonlinear Euler equations for incompressible stratified fluid under the Boussinesq approximation. Initial disturbances of both polarities evolve into stationary, solitary-like waves of corresponding polarity, for which we found the amplitude-width, amplitude-velocity, mass-amplitude, and energy-amplitude relations. Small-amplitude impulses to a good approximation can be described by the modified Korteweg-de Vries equation, but larger waves tend to become wide, and absolute value of their amplitude is bounded by the upper limit. Authors thank prof. K.G. Lamb for the opportunity to use the program code for numerical simulations of Euler equations. The research was supported by RFBR (09-05-00447, 09-05-00204) and by President of RF (MD-3024.2008.5 for young doctors of science).

Vladykina, E. A.; Polukhina, O. E.; Kurkin, A. A.

2009-04-01

264

Experimental determination of the stress intensity factor for cracks with a curvi-linear front in complex components (gas-turbine engine blades)  

Microsoft Academic Search

The use of equipment of linear fracture mechanics to describe laws governing the propagation of fatigue cracks makes itpossible to compum the viability of any design on the most fundamental principles under various conditions of loading and initial crack lengths. The relative simplicity of these computations is possible only with the condition that equations for determination of the stress intensity

A. V. Prokopenko

1981-01-01

265

Dynamics of supercoiled and linear pBluescript II SK(+) Phagemids probed with a long-lifetime metal-ligand complex.  

PubMed

We extended the measurable time scale of DNA dynamics to microsecond using [Ru(phen)(2)(dppz)](2+)(phen = 1,10-phenanthroline, dppz=dipyrido[3,2-a:2',3'-c]phenazine)(RuPD) , which displays a mean lifetime near 500 ns. To evaluate the usefulness of this luminophore (RuPD) for probing nucleic acid dynamics, its intensity and anisotropy decays when intercalated into supercoiled and linear pBluescript (pBS) II SK(+) phagemids were examined using frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetime for the supercoiled phagemids ( = 489.7 ns) was somewhat shorter than that for the linear phagemids ( = 506.4 ns), suggesting a more efficient shielding from water by the linear phagemids. The anisotropy decay data also showed somewhat shorter slow rotational correlation times for supercoiled phagemids (997.2 ns) than for the linear phagemids (1175.6 ns). The slow and fast rotational correlation times appear to be consistent with the bending and torsional motions of the phagemids, respectively. These results indicate that RuPD can have applications in studies of both bending and torsional dynamics of nucleic acids. PMID:15715954

Kang, Jung Sook; Son, Byeng Wha; Choi, Hong Dae; Yoon, Ji Hye; Son, Woo Sung

2005-01-31

266

Heat conduction in a symmetric body subjected to a current flow of symmetric input and output  

Microsoft Academic Search

Steady heat conduction in symmetrical electro-thermal problems is analyzed under the influence of a steady direct current passing through symmetrical regions of the boundary. In the present approach, solution is obtained by dividing the temperature field of the electro-thermal problem into two fields—one is related to the heat conduction problem without Joule heating and the other corresponds to a symmetric

M. Saka; Y. X. Sun; S. Reaz Ahmed

2009-01-01

267

The Topology of Three-Dimensional Symmetric Tensor Fields  

NASA Technical Reports Server (NTRS)

We study the topology of 3-D symmetric tensor fields. The goal is to represent their complex structure by a simple set of carefully chosen points and lines analogous to vector field topology. The basic constituents of tensor topology are the degenerate points, or points where eigenvalues are equal to each other. First, we introduce a new method for locating 3-D degenerate points. We then extract the topological skeletons of the eigenvector fields and use them for a compact, comprehensive description of the tensor field. Finally, we demonstrate the use of tensor field topology for the interpretation of the two-force Boussinesq problem.

Lavin, Yingmei; Levy, Yuval; Hesselink, Lambertus

1994-01-01

268

Symmetric Tensor Decomposition Description of Fermionic Many-Body Wavefunctions  

E-print Network

The configuration interaction (CI) is a versatile wavefunction theory for interacting fermions but it involves an extremely long CI series. Using a symmetric tensor decomposition (STD) method, we convert the CI series into a compact and numerically tractable form. The converted series encompasses the Hartree-Fock state in the first term and rapidly converges to the full-CI state, as numerically tested using small molecules. Provided that the length of the STD-CI series grows only moderately with the increasing complexity of the system, the new method will serve as one of the alternative variational methods to achieve full-CI with enhanced practicability.

Uemura, Wataru

2012-01-01

269

Linear Functions  

NSDL National Science Digital Library

In this tutorial, "Linear functions of the form f(x) = ax + b and the properties of their graphs are explored interactively using an applet." The applet allows students to manipulate variables to discover the changes in intercepts and slope of the graphed line. There are six questions for students to answer, exploring the applet and observing changes. The questions' answers are included on this site. Additionally, a tutorial for graphing linear functions by hand is included.

Shodor

2012-03-29

270

Majorana representation of symmetric multiqubit states  

E-print Network

As early as 1932, Majorana had proposed that a pure permutation symmetric state of N spin- 1 2 particles can be represented by N spinors, which correspond geometrically to N points on the Bloch sphere. Several decades after its conception, the Majorana representation has recently attracted a great deal of attention in connection with multiparticle entanglement. A novel use of this represen- tation led to the classification of entanglement families of permutation symmetric qubits - based on the number of distinct spinors and their arrangement in constituting the multiqubit state. An elegant approach to explore how correlation information of the whole pure symmetric state gets imprinted in its parts is developed for specific entanglement classes of symmetric states. More- over, an elegant and simplified method to evaluate geometric measure of entanglement in N-qubit states obeying exchange symmetry has been developed based on the distribution of the constituent Majorana spionors over the unit sphere. Multiparticle entanglement being a key resource in sev- eral quantum information processing tasks, its deeper understanding is essential. In this review, we present a detailed description of the Majorana representation of pure symmetric states and its applicability in investigating various aspects of multiparticle entanglement.

A. R. Usha Devi; Sudha; A. K. Rajagopal

2011-03-18

271

Bohmian Quantum Gravity in the Linear Field Approximation  

E-print Network

In this paper we have applied Bohmian quantum theory to the linear field approximation of gravity and present a self--consistent quantum gravity theory in the linear field approximation. The theory is then applied to some specific problems, the Newtonian limit, and the static spherically symmetric solution. Some observable effects of the theory are investigated.

Ali Shojai; Fatimah Shojai

2003-06-22

272

Systems of coupled PT-symmetric oscillators  

NASA Astrophysics Data System (ADS)

The Hamiltonian for a PT-symmetric chain of coupled oscillators is constructed. It is shown that if the loss-gain parameter ? is uniform for all oscillators, then as the number of oscillators increases, the region of unbroken PT symmetry disappears entirely. However, if ? is localized in the sense that it decreases for more distant oscillators, then the unbroken PT-symmetric region persists even as the number of oscillators approaches infinity. In the continuum limit the oscillator system is described by a PT-symmetric pair of wave equations, and a localized loss-gain impurity leads to a pseudobound state. It is also shown that a planar configuration of coupled oscillators can have multiple disconnected regions of unbroken PT symmetry.

Bender, Carl M.; Gianfreda, Mariagiovanna; Klevansky, S. P.

2014-08-01

273

Symmetric extension of two-qubit states  

NASA Astrophysics Data System (ADS)

A bipartite state ?AB is symmetric extendible if there exists a tripartite state ?ABB' whose AB and AB' marginal states are both identical to ?AB. Symmetric extendibility of bipartite states is of vital importance in quantum information because of its central role in separability tests, one-way distillation of Einstein-Podolsky-Rosen pairs, one-way distillation of secure keys, quantum marginal problems, and antidegradable quantum channels. We establish a simple analytic characterization for symmetric extendibility of any two-qubit quantum state ?AB; specifically, tr(?B2)?tr(?AB2)-4? det?AB . As a special case we solve the bosonic three-representability problem for the two-body reduced density matrix.

Chen, Jianxin; Ji, Zhengfeng; Kribs, David; Lütkenhaus, Norbert; Zeng, Bei

2014-09-01

274

Spherically Symmetric Thick Branes Cosmological Evolution  

E-print Network

Spherically symmetric time-dependent solutions for the 5D system of a scalar field canonically coupled to gravity are obtained and identified as an extension of recent results obtained by Ahmed, Grzadkowskia and Wudkab. The corresponding cosmology of models with regularized branes generated by such a 5D scalar field scenario is also investigated. It has been shown that the anisotropic evolution of the warp factor and consequently the Hubble like parameter are both driven by the radial coordinate on the brane, which leads to an emergent thick brane-world scenario with spherically symmetric time dependent warp factor. Meanwhile, the separability of variables depending on fifth dimension, y, which is exhibited by the equations of motion, allows one to recover the extra dimensional profiles obtained in the literature, namely the extra dimensional part of the scale (warp) factor and the scalar field dependence on y. Therefore, our results are mainly concerned with the time dependence of a spherically symmetric war...

Bernardini, Alex E; da Rocha, Roldao

2014-01-01

275

A Mn(III)-superoxo complex of a zwitterionic calix[4]arene with an unprecedented linear end-on Mn(III)-O2 arrangement and good catalytic performance for alkene epoxidation.  

PubMed

Reactions of [H(4)L][PF(6)](4) with 4 equiv. of Mn(OAc)(2)·4H(2)O in the presence of air gave rise to a mononuclear Mn(III)-superoxo complex [Mn(III)L(O(2))(H(2)O)](PF(6))(2), which contains a bowl-shaped cationic structure with a D(4d) symmetry. It has an unprecedented linear end-on Mn(III)-O(2) unit and exhibited good efficiency and selectivity in the catalytic oxidation of alkenes with O(2) plus isobutyraldehyde under mild conditions. PMID:21892451

Liu, Lei-Lei; Li, Hong-Xi; Wan, Li-Min; Ren, Zhi-Gang; Wang, Hui-Fang; Lang, Jian-Ping

2011-10-21

276

Observational tests of Baryon symmetric cosmology  

NASA Technical Reports Server (NTRS)

Observational evidence for Baryon symmetric (matter/antimatter) cosmology and future observational tests are reviewed. The most significant consequences of Baryon symmetric cosmology lie in the prediction of an observable cosmic background of gamma radiation from the decay of pi(0)-mesons produced in nucleon-antinucleon annihilations. Equations for the prediction of the amma ray background spectrum for the case of high redshifts are presented. The theoretical and observational plots of the background spectrum are shown to be in good agreement. Measurement of cosmic ray antiprotons and the use of high energy neutrino astronomy to look for antimatter elsewhere in the universe are also addressed.

Stecker, F. W.

1982-01-01

277

Symmetric integrator for nonintegrable Hamiltonian relativistic systems  

NASA Astrophysics Data System (ADS)

By combining a standard symmetric, symplectic integrator with a new step size controller, we provide an integration scheme that is symmetric, reversible and conserves the values of the constants of motion. This new scheme is appropriate for long-term numerical integrations of geodesic orbits in spacetime backgrounds, whose corresponding Hamiltonian system is nonintegrable, and, in general, for any nonintegrable Hamiltonian system whose kinetic part depends on the position variables. We show by numerical examples that the new integrator is faster and more accurate (i) than the standard symplectic integration schemes with or without standard adaptive step size controllers and (ii) than an adaptive step Runge-Kutta scheme.

Seyrich, Jonathan; Lukes-Gerakopoulos, Georgios

2012-12-01

278

Modelling of partially-resolved oceanic symmetric instability  

NASA Astrophysics Data System (ADS)

A series of idealized numerical models have been developed to investigate the effects of partially resolved symmetric instability (SI) in oceanic general circulation models. An analysis of the energetics of symmetric instability is used to argue that the mixed layer can be at least partially restratified even when some SI modes are absent due to either large horizontal viscosity or coarse model resolution. Linear stability analysis reveals that in the idealized models the amount of restratification can be predicted as a function of the grid spacing and viscosity. The models themselves are used to demonstrate these predictions and reveal three possible outcomes in steady-state: (1) incomplete restratification due to viscosity, (2) incomplete restratification due to resolution, and (3) excessive restratification due to anisotropy of the viscosity. The third outcome occurs even on a high-resolution isotropic grid and in two separate numerical models, and thus appears to be a sort of robust numerical feature. The three outcomes are used to recommend criteria that a successful SI parameterization should satisfy.

Bachman, S. D.; Taylor, J. R.

2014-10-01

279

A modified direct preconditioner for indefinite symmetric Toeplitz systems  

SciTech Connect

A modification is presented of the classical O(n[sup 2]) algorithm of Trench for the direct solution of Toeplitz systems of equations. The Trench algorithm can be guaranteed to be stable only for matrices that are (symmetric) positive definite; it is generally unstable otherwise. The modification permits extension of the algorithm to compute an approximate inverse in the indefinite symmetric case, for which the unmodified algorithm breaks down when principal submatrices are singular. As a preconditioner, this approximate inverse has an advantage that only matrix-vector multiplications are required for the solution of a linear system, without forward and backward solves. The approximate inverse so obtained can be sufficiently accurate, moreover, that, when it is used as a preconditioner for the applications investigated, subsequent iteration may not even be necessary. Numerical results are given for several test matrices. The perturbation to the original matrix that defines the modification is related to a perturbation in a quantity generated in the Trench algorithm; the associated stability of the Trench algorithm is discussed.

Concus, P. (Lawrence Berkeley Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Mathematics); Saylor, P. (Illinois Univ., Urbana, IL (United States). Dept. of Computer Science)

1992-11-01

280

A modified direct preconditioner for indefinite symmetric Toeplitz systems  

SciTech Connect

A modification is presented of the classical O(n{sup 2}) algorithm of Trench for the direct solution of Toeplitz systems of equations. The Trench algorithm can be guaranteed to be stable only for matrices that are (symmetric) positive definite; it is generally unstable otherwise. The modification permits extension of the algorithm to compute an approximate inverse in the indefinite symmetric case, for which the unmodified algorithm breaks down when principal submatrices are singular. As a preconditioner, this approximate inverse has an advantage that only matrix-vector multiplications are required for the solution of a linear system, without forward and backward solves. The approximate inverse so obtained can be sufficiently accurate, moreover, that, when it is used as a preconditioner for the applications investigated, subsequent iteration may not even be necessary. Numerical results are given for several test matrices. The perturbation to the original matrix that defines the modification is related to a perturbation in a quantity generated in the Trench algorithm; the associated stability of the Trench algorithm is discussed.

Concus, P. [Lawrence Berkeley Lab., CA (United States)]|[California Univ., Berkeley, CA (United States). Dept. of Mathematics; Saylor, P. [Illinois Univ., Urbana, IL (United States). Dept. of Computer Science

1992-11-01

281

Linear Algebra  

NSDL National Science Digital Library

A mathematics professor from Saint Michael's College is the author of this free online textbook about linear algebra. Being just shy of 450 pages, the book is very comprehensive and of high quality. It gives an excellent introduction into topics such as vector spaces, linear systems, and determinants, and the author is quite good at defining a consistent notation throughout the book. Each chapter has several examples that demonstrate the concepts, concluding with exercises to be solved by the reader. Solutions to the exercises are given in a separate file. [CL

Hefferon, Jim.

282

Eigenmodes of symmetric plasmonic waveguides S. F. Helfert, A. G. Edelmann, J. Jahns  

E-print Network

Eigenmodes of symmetric plasmonic waveguides S. F. Helfert, A. G. Edelmann, J. Jahns At the interface between metals and dielectric materials so called plasmon waves can propagate [1]. Due) Two-dimensional plasmonic waveguide; b) propagation constant in the complex plane [1] H. Raether

Jahns, Jürgen

283

Critical mass phenomenon for a chemotaxis kinetic model with spherically symmetric initial data  

E-print Network

' process performed by E. coli [13]. However, this fits well with motion of bigger and more complex cellsCritical mass phenomenon for a chemotaxis kinetic model with spherically symmetric initial data a critical mass phenomenon occuring in a model for cell self-organization via chemotaxis. The very well known

Paris-Sud XI, Université de

284

Two loop QCD vertices at the symmetric point  

SciTech Connect

We compute the triple gluon, quark-gluon and ghost-gluon vertices of QCD at the symmetric subtraction point at two loops in the MS scheme. In addition we renormalize each of the three vertices in their respective momentum subtraction schemes, MOMggg, MOMq and MOMh. The conversion functions of all the wave functions, coupling constant and gauge parameter renormalization constants of each of the schemes relative to MS are determined analytically. These are then used to derive the three loop anomalous dimensions of the gluon, quark, Faddeev-Popov ghost and gauge parameter as well as the {beta} function in an arbitrary linear covariant gauge for each MOM scheme. There is good agreement of the latter with earlier Landau gauge numerical estimates of Chetyrkin and Seidensticker.

Gracey, J. A. [Theoretical Physics Division, Department of Mathematical Sciences, University of Liverpool, P.O. Box 147, Liverpool, L69 3BX (United Kingdom)

2011-10-15

285

Exciton scattering on symmetric branching centers in conjugated molecules.  

PubMed

The capability of the exciton scattering approach, an efficient methodology for excited states in branched conjugated molecules, is extended to include symmetric triple and quadruple joints that connect linear segments on the basis of the phenylacetylene backbone. The obtained scattering matrices that characterize these vertices are used in application of our approach to several test structures, where we find excellent agreement with the transition energies computed by the reference quantum chemistry. We introduce topological charges, associated with the scattering matrices, which help to formulate useful relations between the number of excitations in the exciton band and the number of repeat units. The obtained features of the scattering phases are analyzed in terms of the observed excited state electronic structure. PMID:21194223

Li, Hao; Wu, Chao; Malinin, Sergey V; Tretiak, Sergei; Chernyak, Vladimir Y

2011-05-12

286

Clay content analysis across landscape by means of linear and non-linear empirical models  

NASA Astrophysics Data System (ADS)

In soil science literature there exist many applications that deals with the spatial prediction of soil features by means of a set of statistical techniques. In this work the amount of clay content at level of soil horizon was put in a spatial framework and analyzed using four alternative models for describing its variability in a geopedological complex landscape such as Telese valley (Campania, South Italy) study area. Three statistical models were involved, that is (i) the multiple linear regression (MLR), (ii) the multicollocated ordinary cokriging (MOCOK), and (iii) a two-layers FFBP (FeedForward Back-Propagation) neural network with topology 6 : 1 (ANN). Apart from these technologies (neurocomputing, and multivariate regression and geostatistics) a polygonal soil map (UDP) was also used for the sake of comparing complex and sometimes cumbersome models with the standard approach of representing the soil spatial distribution. Clay data was splitted in calibration/validation subsets in order to unbiasedly compare the four models (in order of complexity UDP, MLR, MOCOK, ANN). Comparison was based on multi-criteria assessment using six measures of performance: RMSE (root mean square error), MBE (mean bias error), Pearson's correlation (r), an efficiency index (eff), SMAPE (symmetrical mean absolute percent error), and Wilmott's agreement index (D). Generally all indicators seem to demonstrate that the more complex (from UDP to ANN) the models the better their performance in representing the spatial variability of some pedological parameters. Despite such statement much endeavour should be spent in model comparison by considering also the cost/profit trade off incorporating a cost function.

Langella, G.; Minieri, L.; Terribile, F.

2009-04-01

287

Local conservation laws in nonlinear sigma models based on symmetric spaces  

SciTech Connect

The formalism of a class of two-dimensional field theories known as nonlinear sigma models based on a symmetric space is reviewed, and the projective representation of such a symmetric space is used to find a natural geometric interpretation for the Riccati-like equations, and the consequent infinity of local conservation laws, for these models. The inverse scattering method, which has been used to great effect in the search for exact solutions to certain nonlinear partial differential equations in two variables is reviewed. These general methods are illustrated by applying them to the Korteweg-de Vries equation. After a short mathematical digression on symmetric spaces, the inverse scattering formalism is developed for nonlinear sigma models in which the fundamental field takes values in a symmetric space G/H, where G is the global invariance group of the model, and H is a subset of G is the hidden local invariance group. The isospectral pair of the inverse scattering method is interpreted as expressing the infinitesimal linear action of the group G on itself. On the other hand, the group G can be taken to act nonlinear on one of its associated symmetric spaces G/H. This nonlinear action is taken to be infinitesimal. A pair of Riccati-like equations is found. A natural geometric interpretation for the Riccati equations which in the literature appear ex nihilo is found.

Snyder, M.A.

1982-01-01

288

Amplituhedron cells and Stanley symmetric functions  

E-print Network

The amplituhedron was recently introduced in the study of scattering amplitudes in $N=4$ super Yang-Mills. We compute the cohomology class of a tree amplituhedron subvariety of the Grassmannian to be the truncation of an affine Stanley symmetric function.

Thomas Lam

2014-08-23

289

ccsd00002799, KILLING FORMS ON SYMMETRIC SPACES  

E-print Network

de#12;nitions of Killing vector #12;elds on Riemannian manifolds. A vector #12;eld X is Killing AND UWE SEMMELMANN Proposition 1.2. A symmetric space admitting real Killing spinors is locally confor carry Killing spinors is locally irreducible (cf. [3]) and using the squaring construction one can

290

ECG compression using discrete symmetric wavelet transform  

Microsoft Academic Search

This paper proposes a new ECG signal compression algorithm using a discrete symmetric wavelet transform. This proposed compression scheme may find applications in digital Holter recording, in ECG signal archiving and in ECG data transmission through communication channels. Using the new method, a compression ratio of 8 to 1 can be achieved with PRD=3.9%, in contrast to the AZTEC compression

A. Djohan; T. Q. Nguyen; W. J. Tompkins

1995-01-01

291

Symmetries of Locally Rotationally Symmetric Models  

E-print Network

Matter collineations of locally rotationally symmetric spacetimes are considered. These are investigated when the energy-momentum tensor is degenerate. We know that the degenerate case provides infinite dimensional matter collineations in most of the cases. However, an interesting case arises where we obtain proper matter collineations. We also solve the constraint equations for a particular case to obtain some cosmological models.

M. Sharif

2005-06-08

292

Reciprocal Symmetric and Origin of Quantum Statistics  

E-print Network

Boltzmann's differential equation is replaced by the corresponding reciprocal symmetric finite difference equation. Finite difference translates discreteness of energy. Boltzmann's function, then, splits into two reciprocally related functions. One of them gives Planck's radiation relation and the other one gives the corresponding Fermi-Dirac relation.

Mushfiq Ahmad

2007-03-21

293

Network Organizations: Symmetric Cooperation or Multivalent Negotiation?  

E-print Network

Network Organizations: Symmetric Cooperation or Multivalent Negotiation? Hamid R. Ekbia1 & Rob-169 Abstract The network model of organization plays a central role in recent sociological accounts and technology intensive. Such themes are normally based on a "networking logic" that assumes the trustful

Indiana University

294

Dissociative Recombination of Highly Symmetric Polyatomic Ions  

NASA Astrophysics Data System (ADS)

A general first-principles theory of dissociative recombination is developed for highly symmetric molecular ions and applied to H3O+ and CH3+, which play an important role in astrophysical, combustion, and laboratory plasma environments. The theoretical cross sections obtained for the dissociative recombination of the two ions are in good agreement with existing experimental data from storage ring experiments.

Douguet, Nicolas; Orel, Ann E.; Greene, Chris H.; Kokoouline, Viatcheslav

2012-01-01

295

Acoustic horizons in axially symmetric relativistic accretion  

Microsoft Academic Search

Transonic accretion onto astrophysical objects is a unique example of an analogue black hole realized in nature. In the framework of acoustic geometry, we study axially symmetric accretion and wind of a rotating astrophysical black hole or of a neutron star assuming isentropic flow of a fluid described by a polytropic equation of state. In particular, we analyse the causal

Hrvoje Abraham; Neven Bili?; Tapas K. Das

2006-01-01

296

Geometry of PT-symmetric quantum mechanics  

Microsoft Academic Search

Recently, much research has been carried out on Hamiltonians that are not Hermitian but are symmetric under space-time reflection, that is, Hamiltonians that exhibit PT symmetry. Investigations of the Sturm-Liouville eigenvalue problem associated with such Hamiltonians have shown that in many cases the entire energy spectrum is real and positive and that the eigenfunctions form an orthogonal and complete basis.

Carl M. Bender; Dorje C. Brody; Bernhard K. Meister

2007-01-01

297

Entanglement classes of symmetric Werner states  

SciTech Connect

The symmetric Werner states for n qubits, important in the study of quantum nonlocality and useful for applications in quantum information, have a surprisingly simple and elegant structure in terms of tensor products of Pauli matrices. Further, each of these states forms a unique local unitary equivalence class, that is, no two of these states are interconvertible by local unitary operations.

Lyons, David W.; Walck, Scott N. [Lebanon Valley College, Annville, Pennsylvania 17003 (United States)

2011-10-15

298

Entanglement classes of symmetric Werner states  

E-print Network

The symmetric Werner states for $n$ qubits, important in the study of quantum nonlocality and useful for applications in quantum information, have a surprisingly simple and elegant structure in terms of tensor products of Pauli matrices. Further, each of these states forms a unique local unitary equivalence class, that is, no two of these states are interconvertible by local unitary operations.

David W. Lyons; Scott N. Walck

2011-06-21

299

Iris Recognition Using Circular Symmetric Filters  

Microsoft Academic Search

This paper proposes a new method for personal identification based on iris recognition. The method consists of three major components: image preprocessing, feature extraction and classifier design. A bank of circular symmetric filters is used to capture local iris characteristics to form a fixed length feature vector. In iris matching, an efficient approach called nearest feature line (NFL) is used.

Li Ma; Yunhong Wang; Tieniu Tan

2002-01-01

300

Ferromagnetic behavior in linear charge-transfer complexes. Structural and magnetic characterization of octamethylferrocene salts: (Fe(C sub 5 Me sub 4 H) sub 2 ) sup sm bullet + (A) sup sm bullet minus (A = TCNE, TCNQ)  

SciTech Connect

The reaction of Fe{sup II}({eta}{sup 5}-C{sub 5}Me{sub 4}H){sub 2} with cyano acceptors A (A = TCNE (tetracyanoethylene), TCNQ (7,7,8,8-tetracyano-p-quanodimethane), n-C{sub 4}(CN){sub 6} (n-hexacyanobutadiene), C{sub 6}(CN){sub 6} (tris(dicyanomethylene)cyclopropane), DDQ (2,3-dichloro-5,6-dicyanobenzoquinone), TCNQF{sub 4} (perfluoro-7,7,8,8-tetracyano-p-quinodimethane) results in formation of 1:1 charge-transfer salts of (Fe{sup III})(C{sub 5}Me{sub 4}H){sub 2}){sup {sm bullet}+}(A){sup {sm bullet}{minus}} composition. The TCNE and TCNQ complexes have been structurally characterized. The high-temperature magnetic susceptibility for polycrystalline samples of these complexes can be fit by the Curie-Qeiss law, {chi} = C(T-{theta}){sup {minus}1}, with {theta} = +0.5 {plus minus} 2.2 K, and {mu}{sub eff} ranges from 2.71 to 3.97 {mu}{sub B}, suggesting that the polycrystalline samples measured had varying degrees of orientation. The 7.0 K EPR spectrum of the radical cation exhibits an axially symmetric powder pattern with g{sub {parallel}} = 4.11 and g{sub {perpendicular}} = 1.42, and the EPR parameters are essentially identical with those reported for ferrocenium and decamethylferrocenium. No EPR spectrum is observed at 78 K. Akin to the (Fe(C{sub 5}Me{sub 5}){sub 2}){sup {sm bullet}+} salts, these salts have {sup 57}Fe Moessbauer spectra consistent with complete charge transfer; however, unlike the case for the former complexes, quadrupole splittings of 0.30 and 0.220 mm/s are observed at 4.8 and 298 K, respectively. The absence of strong interionic magnetic coupling for the (Fe(C{sub 5}Me{sub 4}H){sub 2}){sup {sm bullet}+} salts contrasts with the behavior of the (Fe(C{sub 5}Me{sub 5}){sub 2}){sup {sm bullet}+} salts. 26 refs., 13 figs., 8 tabs.

Miller, J.S.; Glatzhofer, D.T.; O'Hare, D.M. (E.I. de Pont de Nemours and Co., Inc., Wilmington, DE (USA)); Reiff, W.M. (Northeastern Univ., Boston, MA (USA)); Chakraborty, A.; Epstein, A.J. (Ohio Sate Univ., Columbus (USA))

1989-07-26

301

Differential complexes and exterior calculus  

E-print Network

In this paper we present a new theory of calculus over $k$-dimensional domains in a smooth $n$-manifold, unifying the discrete, exterior, and continuum theories. The calculus begins at a single point and is extended to chains of finitely many points by linearity, or superposition. It converges to the smooth continuum with respect to a norm on the space of ``pointed chains,'' culminating in the chainlet complex. Through this complex, we discover a broad theory of coordinate free, multivector analysis in smooth manifolds for which both the classical Newtonian calculus and the Cartan exterior calculus become special cases. The chainlet operators, products and integrals apply to both symmetric and antisymmetric tensor cochains. As corollaries, we obtain the full calculus on Euclidean space, cell complexes, bilayer structures (e.g., soap films) and nonsmooth domains, with equal ease. The power comes from the recently discovered prederivative and preintegral that are antecedent to the Newtonian theory. These lead to new models for the continuum of space and time, and permit analysis of domains that may not be locally Euclidean, or locally connected, or with locally finite mass.

Jenny Harrison

2006-01-09

302

Application of non-linear angle synchronous spectrofluorimetry to the determination of complex mixtures of drugs in urine: a comparative study.  

PubMed

Synchronous fluorescence spectroscopy (SFS) is a rapid, sensitive and non-destructive method suitable for the analysis of multifluorophoric mixtures. In this study non linear variable angle synchronous spectrofluorimetry was applied to the determination of three fluoroquinololes in urine. Although this technique provides very good results, total resolution of multicomponent mixtures is not always achieved when the spectral profiles strongly overlap. Partial least-squares regression (PLS-1) was utilized to a develop calibration model that related synchronous fluorescence spectra to the analytical concentration of fluoroquinolones in the presence of urine. The same multicomponent mixture was determined using excitation emission matrix fluorescence (EEMF) along with N-way partial least squares regression (N-PLS and U-PLS). The determination was carried out in micellar medium 0.01 M with a pH of 4.8 provided by 0.2 M sodium acetate/acetic acid buffer. A central composite design was selected to obtain a calibration matrix of 25 standards plus a blank sample. The proposed methods were validated by application to a test set of synthetic samples. The results show that SFS with PLS-1 is a better method compared to EEMF with N-PLS or U-PLS because of the low RMSEP values of the former. PMID:23021891

Murillo Pulgarín, J A; Alañón Molina, A; Boras, N

2012-12-01

303

Development of the Complex General Linear Model in the Fourier Domain: Application to fMRI Multiple Input-Output Evoked Responses for Single Subjects  

PubMed Central

A linear time-invariant model based on statistical time series analysis in the Fourier domain for single subjects is further developed and applied to functional MRI (fMRI) blood-oxygen level-dependent (BOLD) multivariate data. This methodology was originally developed to analyze multiple stimulus input evoked response BOLD data. However, to analyze clinical data generated using a repeated measures experimental design, the model has been extended to handle multivariate time series data and demonstrated on control and alcoholic subjects taken from data previously analyzed in the temporal domain. Analysis of BOLD data is typically carried out in the time domain where the data has a high temporal correlation. These analyses generally employ parametric models of the hemodynamic response function (HRF) where prewhitening of the data is attempted using autoregressive (AR) models for the noise. However, this data can be analyzed in the Fourier domain. Here, assumptions made on the noise structure are less restrictive, and hypothesis tests can be constructed based on voxel-specific nonparametric estimates of the hemodynamic transfer function (HRF in the Fourier domain). This is especially important for experimental designs involving multiple states (either stimulus or drug induced) that may alter the form of the response function. PMID:23840281

Rio, Daniel E.; Rawlings, Robert R.; Woltz, Lawrence A.; Gilman, Jodi; Hommer, Daniel W.

2013-01-01

304

Symmetric and skew-symmetric weight functions in perturbation models of 2D interfacial cracks  

E-print Network

In this paper we address the vector problem of a 2D interfacial crack loaded by a general asymmetric distribution of forces acting on its faces. It is shown that the general integral formula for the evaluation of stress intensity factors, as well as high-order terms, requires both symmetric and skew-symmetric weight function matrices. The symmetric weight function matrix is obtained via the solution of a Wiener-Hopf functional equation, whereas the derivation of the skew-symmetric weight function matrix requires the construction of the corresponding full field singular solution. The weight function matrices are then used in the perturbation analysis of a crack advancing quasi-statically along the interface between two dissimilar media. A general and rigorous asymptotic procedure is developed to compute the perturbations of stress intensity factors as well as high-order terms.

Piccolroaz, A; Movchan, A B

2008-01-01

305

Symmetric and skew-symmetric weight functions in perturbation models of 2D interfacial cracks  

E-print Network

In this paper we address the vector problem of a 2D half-plane interfacial crack loaded by a general asymmetric distribution of forces acting on its faces. It is shown that the general integral formula for the evaluation of stress intensity factors, as well as high-order terms, requires both symmetric and skew-symmetric weight function matrices. The symmetric weight function matrix is obtained via the solution of a Wiener-Hopf functional equation, whereas the derivation of the skew-symmetric weight function matrix requires the construction of the corresponding full field singular solution. The weight function matrices are then used in the perturbation analysis of a crack advancing quasi-statically along the interface between two dissimilar media. A general and rigorous asymptotic procedure is developed to compute the perturbations of stress intensity factors as well as high-order terms.

A. Piccolroaz; G. Mishuris; A. B. Movchan

2008-12-24

306

Linear Algebra  

NSDL National Science Digital Library

This course, presented by MIT and taught by Professor Gilbert Strang, provides undergraduate level algebra instruction. The materials cover matrix theory and linear algebra including systems of equations, vector spaces, determinants, eigenvalues, similarity, and positive definite matrices. The course includes video lectures, assignments and exams (with solutions) and lecture notes. MIT presents OpenCourseWare as free educational material online. No registration or enrollment is required to use the materials.

Strang, Gilbert

2010-12-09

307

Linear Models  

NSDL National Science Digital Library

This site uses linear models to demonstrate the change in bird populations on a barren island over time, supply and demand, and the natural cleaning of a polluted lake by fresh water over time. The problems are laid out and turned into both graphic and equation form in order to understand the rate of change happening in each scenario. There are also links to previously covered materials that can help student review material from past math lessons.

Wattenberg, Frank

1997-01-01

308

Photophysics and non-linear absorption of Au(i) and Pt(ii) acetylide complexes of a thienyl-carbazole chromophore.  

PubMed

In order to understand the photophysics and non-linear optical properties of carbazole containing ?-conjugated oligomers of the type ET-Cbz-TE (E = ethynylene, T = 2,5-thienylene, Cbz = 3,6-carbazole), a detailed investigation was carried out on a series of oligomers that feature Au(i) or Pt(ii) acetylide "end groups", as well as a Pt(ii)-acetylide linked polymer (CBZ-Au-1 and CBZ-Pt-1, CBZ-Poly-Pt). These organometallic chromophores were characterized by UV-visible absorption and variable temperature photoluminescence spectroscopy, nanosecond transient absorption spectroscopy, open aperture nanosecond z-scan and two photon absorption (2PA) spectroscopy. The Au(i) and Pt(ii) oligomers and polymer exhibit weak fluorescence in fluid solution at room temperature. Efficient phosphorescence is observed from the Pt(ii) systems below 150 K in a solvent glass; however, the Au(i) oligomer exhibits only weak phosphorescence at 77 K. Taken together, the emission results indicate that the intersystem crossing efficiency for the Pt(ii) chromophores is greater than for the Au(i) oligomer. Nonetheless, nanosecond transient absorption indicates that direct excitation affords moderately long-lived triplet states for all of the chromophores. Open aperture z-scan measurement shows effective optical attenuation can be achieved by using these materials. The 2PA cross section in the degenerate S0?S1 transition region was in the range 10-100 GM, and increased monotonically toward shorter wavelengths, reaching 800-1000 GM at 550 nm. PMID:25222112

Goswami, Subhadip; Wicks, Geoffrey; Rebane, Aleksander; Schanze, Kirk S

2014-11-12

309

Perturbed Self-Similar Massless Scalar Field in Spherically Symmetric Spaceimes  

E-print Network

In this paper, we investigate the linear perturbations of the spherically symmetric spacetimes with kinematic self-similarity of the second kind. The massless scalar field equations are solved which yield the background and an exact solutions for the perturbed equations. We discuss the boundary conditions of the resulting perturbed solutions. The possible perturbation modes turn out to be stable as well as unstable. The analysis leads to the conclusion that there does not exist any critical solution.

M. Sharif

2007-04-27

310

Dynamic response and stability of a rotor-support system with non-symmetric bearing clearances  

Microsoft Academic Search

The non-linear vibrations of a rotordynamic system that is subjected to non-symmetric bearing clearance effects, are considered. Particular attention is paid to the system response near the primary resonance. Based on a Jeffcott rotor model, the steady-state oscillations and their stability are analysed employing the method of multiple scales. The “normal-loose” rotor stiffness condition, that occurs due to the bearing

R. Ganesan

1996-01-01

311

Correlation between slow magnetic relaxation and the coordination structures of a family of linear trinuclear Zn(II)-Ln(III)-Zn(II) complexes (Ln = Tb, Dy, Ho, Er, Tm and Yb).  

PubMed

Six linear trinuclear [Ln{Zn(L)(AcO)}(2)]BPh(4) complexes (H(2)L denotes the Schiff-base ligand formed by a condensation reaction between ethylenediamine and two equivalents of o-vanillin), including Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5) and Yb (6) were synthesized and were confirmed to be isostructural via X-ray crystallographic analyses. The Ln(III) ion in each complex is deca-coordinated by four equatorial oxygen donors from the methoxo groups of the Schiff-base ligands, two oxygen donors from the acetate anions and four axial oxygen donors from the phenoxo groups of the Schiff-base ligands. AC susceptibility measurements, with an oscillating frequency of 10 to 10,000 Hz, revealed that 1, 2, 4 and 6 show slow magnetic relaxation under a 1000 Oe DC bias field, which occurs via a single process, as confirmed by the semi-circular Cole-Cole plots. These complexes are considered to be field-induced single-molecule magnets under these conditions. The presence or absence of the slow magnetic relaxation process is discussed by correlating the characteristic magnetic anisotropy of each Ln(III) ion with the ligand field anisotropy. PMID:22898750

Maeda, Moe; Hino, Shiori; Yamashita, Kei; Kataoka, Yumiko; Nakano, Motohiro; Yamamura, Tomoo; Kajiwara, Takashi

2012-11-28

312

(1+1)-Dirac particle with position-dependent mass in complexified Lorentz scalar interactions: effectively PT-symmetric  

E-print Network

The effect of the built-in supersymmetric quantum mechanical language on the spectrum of the (1+1)-Dirac equation, with position-dependent mass (PDM) and complexified Lorentz scalar interactions, is re-emphasized. The signature of the "quasi-parity" on the Dirac particles' spectra is also studied. A Dirac particle with PDM and complexified scalar interactions of the form S(z)=S(x-ib) (an inversely linear plus linear, leading to a PT-symmetric oscillator model), and S(x)=S_{r}(x)+iS_{i}(x) (a PT-symmetric Scarf II model) are considered. Moreover, a first-order intertwining differential operator and an $\\eta$-weak-pseudo-Hermiticity generator are presented and a complexified PT-symmetric periodic-type model is used as an illustrative example.

Omar Mustafa; S. Habib Mazharimousavi

2006-11-14

313

PT-symmetric representations of fermionic algebras  

SciTech Connect

A recent paper by Jones-Smith and Mathur, Phys. Rev. A 82, 042101 (2010) extends PT-symmetric quantum mechanics from bosonic systems (systems for which T{sup 2}=1) to fermionic systems (systems for which T{sup 2}=-1). The current paper shows how the formalism developed by Jones-Smith and Mathur can be used to construct PT-symmetric matrix representations for operator algebras of the form {eta}{sup 2}=0, {eta}{sup 2}=0, {eta}{eta}+{eta}{eta}={alpha}1, where {eta}={eta}{sup PT}=PT{eta}T{sup -1}P{sup -1}. It is easy to construct matrix representations for the Grassmann algebra ({alpha}=0). However, one can only construct matrix representations for the fermionic operator algebra ({alpha}{ne}0) if {alpha}=-1; a matrix representation does not exist for the conventional value {alpha}=1.

Bender, Carl M. [Physics Department, Washington University, St. Louis, Missouri 63130 (United States); Klevansky, S. P. [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 19, D-69120 Heidelberg (Germany)

2011-08-15

314

Spherically symmetric random walks in noninteger dimension  

SciTech Connect

A previous article proposed a new kind of random walk on a spherically symmetric lattice in arbitrary noninteger dimension [ital D]. Such a lattice avoids the problems associated with a hypercubic lattice in noninteger dimension. This article examines the nature of spherically symmetric random walks in detail. A large-time asymptotic analysis of these random walks is performed and the results are used to determine the Hausdorff dimension of the process. Exact results are obtained in terms of Hurwitz functions (incomplete zeta functions) for the probability of a walker going from one region of the spherical lattice to another. Finally, it is shown that the probability that the paths of [ital K] independent random walkers will intersect vanishes in the continuum limit if [ital D][gt]2[ital K]/([ital K][minus]1).

Bender, C.M. (Department of Physics, Washington University, St. Louis, Missouri 63130-4899 (United States)); Boettcher, S. (Department of Physics, Brookhaven National Laboratory, Upton, New York 11973 (United States)); Moshe, M. (Department of Physics, Technion Israel Institute of Technology, Haifa 32000 (Israel))

1994-09-01

315

Binary switching in a 'symmetric' potential landscape  

PubMed Central

A binary switch is the basic building block for information processing. The potential energy profile of a bistable binary switch is a ‘symmetric' double well. The traditional method of switching it from one state (one well) to the other is to tilt the profile towards the desired state. Here, we present a case, where no such tilting is necessary to switch successfully, even in the presence of thermal noise. This happens because of the built-in dynamics inside the switch itself. It differs from the general perception on binary switching that in a ‘symmetric' potential landscape, the switching probability is 50% in the presence of thermal noise. Our results, considering the complete three-dimensional potential landscape, demonstrate intriguing phenomena on binary switching mechanism. With experimentally feasible parameters, we theoretically demonstrate such intriguing possibility in electric field induced magnetization switching of a shape-anisotropic single-domain magnetostrictive nanomagnet with two stable states at room-temperature. PMID:24154561

Roy, Kuntal; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

2013-01-01

316

Parity-time-symmetric plasmonic metamaterials  

NASA Astrophysics Data System (ADS)

We theoretically investigate the optical properties of parity-time (PT)-symmetric three-dimensional metamaterials composed of strongly coupled planar plasmonic waveguides. By tuning the loss-gain balance, we show how the initially isotropic material becomes both asymmetric and unidirectional. Investigation of the band structure near the material's exceptional point reveals several interesting optical properties, including double negative refraction, Bloch power oscillations, unidirectional invisibility, and reflection and transmission coefficients that are simultaneously equal to or greater than unity. The highly tunable optical dispersion of PT-symmetric metamaterials provides a foundation for designing an unconventional class of three-dimensional bulk synthetic media, with applications ranging from lossless subdiffraction-limited optical lenses to nonreciprocal nanophotonic devices.

Alaeian, Hadiseh; Dionne, Jennifer A.

2014-03-01

317

General theory for multiple input-output perturbations in complex molecular systems. 1. Linear QSPR electronegativity models in physical, organic, and medicinal chemistry.  

PubMed

In general perturbation methods starts with a known exact solution of a problem and add "small" variation terms in order to approach to a solution for a related problem without known exact solution. Perturbation theory has been widely used in almost all areas of science. Bhor's quantum model, Heisenberg's matrix mechanincs, Feyman diagrams, and Poincare's chaos model or "butterfly effect" in complex systems are examples of perturbation theories. On the other hand, the study of Quantitative Structure-Property Relationships (QSPR) in molecular complex systems is an ideal area for the application of perturbation theory. There are several problems with exact experimental solutions (new chemical reactions, physicochemical properties, drug activity and distribution, metabolic networks, etc.) in public databases like CHEMBL. However, in all these cases, we have an even larger list of related problems without known solutions. We need to know the change in all these properties after a perturbation of initial boundary conditions. It means, when we test large sets of similar, but different, compounds and/or chemical reactions under the slightly different conditions (temperature, time, solvents, enzymes, assays, protein targets, tissues, partition systems, organisms, etc.). However, to the best of our knowledge, there is no QSPR general-purpose perturbation theory to solve this problem. In this work, firstly we review general aspects and applications of both perturbation theory and QSPR models. Secondly, we formulate a general-purpose perturbation theory for multiple-boundary QSPR problems. Last, we develop three new QSPR-Perturbation theory models. The first model classify correctly >100,000 pairs of intra-molecular carbolithiations with 75-95% of Accuracy (Ac), Sensitivity (Sn), and Specificity (Sp). The model predicts probabilities of variations in the yield and enantiomeric excess of reactions due to at least one perturbation in boundary conditions (solvent, temperature, temperature of addition, or time of reaction). The model also account for changes in chemical structure (connectivity structure and/or chirality paterns in substrate, product, electrophile agent, organolithium, and ligand of the asymmetric catalyst). The second model classifies more than 150,000 cases with 85-100% of Ac, Sn, and Sp. The data contains experimental shifts in up to 18 different pharmacological parameters determined in >3000 assays of ADMET (Absorption, Distribution, Metabolism, Elimination, and Toxicity) properties and/or interactions between 31723 drugs and 100 targets (metabolizing enzymes, drug transporters, or organisms). The third model classifies more than 260,000 cases of perturbations in the self-aggregation of drugs and surfactants to form micelles with Ac, Sn, and Sp of 94-95%. The model predicts changes in 8 physicochemical and/or thermodynamics output parameters (critic micelle concentration, aggregation number, degree of ionization, surface area, enthalpy, free energy, entropy, heat capacity) of self-aggregation due to perturbations. The perturbations refers to changes in initial temperature, solvent, salt, salt concentration, solvent, and/or structure of the anion or cation of more than 150 different drugs and surfactants. QSPR-Perturbation Theory models may be useful for multi-objective optimization of organic synthesis, physicochemical properties, biological activity, metabolism, and distribution profiles towards the design of new drugs, surfactants, asymmetric ligands for catalysts, and other materials. PMID:23889050

González-Díaz, Humberto; Arrasate, Sonia; Gómez-SanJuan, Asier; Sotomayor, Nuria; Lete, Esther; Besada-Porto, Lina; Ruso, Juan M

2013-01-01

318

Z scan using circularly symmetric beams  

Microsoft Academic Search

We report general characteristics of on-axis Z-scan transmittance for arbitrary circularly symmetric beams. Some experimental results are presented for a nearly top-hat-shaped beam and for a trimmed Airy beam whose electric field profile is the central portion of an Airy function inside its first zero. The sensitivity of Z-scan method with a trimmed Airy beam for measuring an induced index-of-refraction

Bum Ku Rhee; Jin Seob Byun; E. W. Van Stryland

1996-01-01

319

PT symmetric Aubry-Andre model  

NASA Astrophysics Data System (ADS)

PT symmetric Aubry-Andre model describes an array of N coupled optical waveguides with position-dependent gain and loss. We show that the reality of the spectrum depends sensitively on the degree of quasi-periodicity for small number of lattice sites. We obtain the Hofstadter butterfly spectrum and discuss the existence of the phase transition from extended to localized states. We show that rapidly changing periodical gain/loss materials almost conserve the total intensity.

Yuce, C.

2014-06-01

320

Expansion-free Cylindrically Symmetric Models  

E-print Network

This paper investigates cylindrically symmetric distribution of an-isotropic fluid under the expansion-free condition, which requires the existence of vacuum cavity within the fluid distribution. We have discussed two family of solutions which further provide two exact models in each family. Some of these solutions satisfy Darmois junction condition while some show the presence of thin shell on both boundary surfaces. We also formulate a relation between the Weyl tensor and energy density.

M. Sharif; Z. Yousaf

2013-10-30

321

Numerical analysis of the symmetric methods  

Microsoft Academic Search

Aimed at the initial value problem of the particular second-order ordinary differential equations,y?=f(x, y), the symmetric methods (Quinlan and Tremaine, 1990) and our methods (Xu and Zhang, 1994) have been compared in detail by integrating the artificial earth satellite orbits in this paper. In the end, we point out clearly that the integral accuracy of numerical integration of the satellite

Ji-Hong Xu; A-Li Zhang

1995-01-01

322

Highly symmetric travelling waves in pipe flow  

Microsoft Academic Search

The recent theoretical discovery of finite-amplitude travelling waves in pipe flow has re-ignited interest in the transitional phenomena that Osborne Reynolds studied 125 years ago. Despite all being unstable, these waves are providing fresh insight into the flow dynamics. Here we describe two new classes of highly-symmetric travelling waves (possessing rotational, shift-&-reflect and mirror symmetries) and report a new family

Chris C. T. Pringle; Yohann Duguet; Rich R. Kerswell

2009-01-01

323

Symmetric correlations as seen at RHIC  

E-print Network

We analyze the forward-backward multiplicity correlation coefficient as measured by STAR. We show that in the most central Au+Au collisions bins located symmetrically around \\eta = 0 with large separation in pseudorapidity are more strongly correlated than bins located asymmetrically with smaller separation. In proton-proton collisions the opposite effect is observed. It suggests a qualitatively different behavior of the two-particle correlation as a function of pseudorapidity sum in p+p and Au+Au collisions.

Adam Bzdak

2011-08-03

324

Solitons in PT-symmetric nonlinear lattices  

SciTech Connect

The existence of localized modes supported by the PT-symmetric nonlinear lattices is reported. The system considered reveals unusual properties: unlike other typical dissipative systems, it possesses families (branches) of solutions, which can be parametrized by the propagation constant; relatively narrow localized modes appear to be stable, even when the conservative nonlinear lattice potential is absent; and finally, the system supports stable multipole solutions.

Abdullaev, Fatkhulla Kh.; Konotop, Vladimir V.; Zezyulin, Dmitry A. [Centro de Fisica Teorica e Computacional, Faculdade de Ciencias, Universidade de Lisboa, Avenida Professor Gama Pinto 2, P-1649-003 Lisboa (Portugal); Kartashov, Yaroslav V. [ICFO-Institut de Ciencies Fotoniques, and Universitat Politecnica de Catalunya, Mediterranean Technology Park, E-08860 Castelldefels, Barcelona (Spain)

2011-04-15

325

Wave equation on spherically symmetric Lorentzian metrics  

SciTech Connect

Wave equation on a general spherically symmetric spacetime metric is constructed. Noether symmetries of the equation in terms of explicit functions of {theta} and {phi} are derived subject to certain differential constraints. By restricting the metric to flat Friedman case the Noether symmetries of the wave equation are presented. Invertible transformations are constructed from a specific subalgebra of these Noether symmetries to convert the wave equation with variable coefficients to the one with constant coefficients.

Bokhari, Ashfaque H.; Al-Dweik, Ahmad Y.; Zaman, F. D. [Department of Mathematics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Kara, A. H. [School of Mathematics, University of the Witwatersrand, Johannesburg (South Africa); Karim, M. [Department of Physics, St. John Fisher College, Rochester, New York 14618 (United States)

2011-06-15

326

Time-symmetrized quantum theory: A critique  

NASA Astrophysics Data System (ADS)

This dissertation considers various claims which have been made by proponents of time-symmetrized quantum theory (TSQT), focusing in particular on the work of Lev Vaidman, who has been the strongest advocate in recent years. These claims attribute ``elements of reality,'' corresponding to dispersion-free values of noncommuting observables, to pre- and post-selected quantum systems via the Aharonov-Bermann-Lebowitz (ABL) rule of time-symmetrized quantum theory. The novelty of the TSQT approach is the assertion that more information can be gained about a system in a symmetric time interval bounded by given past and future measurement outcomes than via the usual, time-asymmetric Born rule requiring that only a pre-selection outcome be given. Such claims, if true, would be valuable for a realist interpretation of quantum theory. The value would lie in the possibility of quantum states with dispersion-free values for noncommuting observables, provided such states are defined time-symmetrically through the use of two-state vectors according to the prescription of TSQT. Thus the basic question to be addressed is: Does TSQT shed any new light on the debate concerning the adequacy of realist interpretations of quantum theory? Answering this question requires a careful evaluation of the counterfactual usage of the ABL rule, which is the only way to obtain the inferences about dispersion-free values. The analysis shows that the counterfactual usage is, in general, invalid, and therefore the program advocated by Vaidman, Aharonov, and others fails to provide new insights into, or support for, a realist interpretation of quantum theory.

Kastner, Ruth Elinor

327

Random walks on highly symmetric graphs  

Microsoft Academic Search

We consider uniform random walks on finite graphs withn nodes. When the hitting times are symmetric, the expected covering time is at least 1\\/2n logn-O(n log logn) uniformly over all such graphs. We also obtain bounds for the covering times in terms of the eigenvalues of the transition matrix of the Markov chain. For distance-regular graphs, a general lower bound

Luc Devroye; Amine Sbihi

1990-01-01

328

Geometry of PT-symmetric quantum mechanics  

Microsoft Academic Search

Recently, much research has been carried out on Hamiltonians that are not\\u000aHermitian but are symmetric under space-time reflection, that is, Hamiltonians\\u000athat exhibit PT symmetry. Investigations of the Sturm-Liouville eigenvalue\\u000aproblem associated with such Hamiltonians have shown that in many cases the\\u000aentire energy spectrum is real and positive and that the eigenfunctions form an\\u000aorthogonal and complete basis.

Carl M. Bender; Dorje C. Brody; Bernhard K. Meister

2007-01-01

329

Planar Poincaré domains: Geometry and Steiner symmetrization  

Microsoft Academic Search

We determine geometric necessary and sufficient conditions on a class of strip-like planar domains in order for them to satisfy\\u000a the Poincaré inequality with exponentp, where 1?pp and generalizes the quasi-hyperbolic metric in the casep=2. As an application, we show that the Poincaré inequality is preserved under Steiner symmetrization of these domains but\\u000a not in general.\\u000a \\u000a We also show that

Wayne Smith; Alexander Stanoyevitch; David A. Stegenga

1995-01-01

330

Symmetric states: local unitary equivalence via stabilizers  

E-print Network

We classify local unitary equivalence classes of symmetric states via a classification of their local unitary stabilizer subgroups. For states whose local unitary stabilizer groups have a positive number of continuous degrees of freedom, the classification is exhaustive. We show that local unitary stabilizer groups with no continuous degrees of freedom are isomorphic to finite subgroups of the rotation group SO(3), and give examples of states with discrete stabilizers.

Curt D. Cenci; David W. Lyons; Laura M. Snyder; Scott N. Walck

2010-07-22

331

Effects of Large Deflection and Transverse Shear on Response of Rectangular Symmetric Composite Laminates Subjected to Acoustic Excitation  

Microsoft Academic Search

Nonlinear equations of motion of symmetrically laminated anisotropic plates are derived considering von Karman strains and transverse shear effects. Using a single-mode Galerkin procedure, a nonlinear modal equation is obtained and a direct equivalent linearization method is employed for solution of this equation. The response of acoustic excitation of moderately thick composite panels is then studied. Further, the effects of

Chuh Mei; C. B. Prasad

1989-01-01

332

High-efficiency Fresnel lens fabricated by axially symmetric photoalignment method.  

PubMed

In this study, a Fresnel lens with radial and azimuthal liquid crystal (LC) alignments in the odd and even zones was fabricated using the photoalignment technique based on an azo dye doped in LC cells. The lens has approximately 35% focusing efficiency as determined using a linearly polarized probe beam. In addition, the lens converts the input linear polarization into axially symmetrical polarization at the focal plane. The fabricated Fresnel lens is polarization-independent and has electrically controllable focusing efficiency. Moreover, the far-field pattern of a probe beam through the device placed between the polarizers agrees with the pattern obtained from the simulation. PMID:23142883

Huang, Yao-Han; Ko, Shih-Wei; Chu, Shu-Chun; Fuh, Andy Ying-Guey

2012-11-10

333

Spatial-frequency Fourier polarimetry of the complex degree of mutual anisotropy of linear and circular birefringence in the diagnostics of oncological changes in morphological structure of biological tissues  

NASA Astrophysics Data System (ADS)

Theory of polarisation-correlation analysis of laser images of histological sections of biopsy material from cervix tissue based on spatial frequency selection of linear and circular birefringence mechanisms is formulated. Comparative results of measuring the coordinate distributions of the complex degree of mutual anisotropy (CDMA), produced by fibrillar networks formed by myosin and collagen fibres of cervix tissue in different pathological conditions, namely, pre-cancer (dysplasia) and cancer (adenocarcinoma), are presented. The values and variation ranges of statistical (moments of the first — fourth order), correlation (excess-autocorrelation functions), and fractal (slopes of approximating curves and dispersion of extrema of logarithmic dependences of power spectra) parameters of the CDMA coordinate distributions are studied. Objective criteria for pathology diagnostics and differentiation of its severity degree are determined.

Ushenko, Yu A.; Gorskii, M. P.; Dubolazov, A. V.; Motrich, A. V.; Ushenko, V. A.; Sidor, M. I.

2012-08-01

334

Spatial-frequency Fourier polarimetry of the complex degree of mutual anisotropy of linear and circular birefringence in the diagnostics of oncological changes in morphological structure of biological tissues  

SciTech Connect

Theory of polarisation-correlation analysis of laser images of histological sections of biopsy material from cervix tissue based on spatial frequency selection of linear and circular birefringence mechanisms is formulated. Comparative results of measuring the coordinate distributions of the complex degree of mutual anisotropy (CDMA), produced by fibrillar networks formed by myosin and collagen fibres of cervix tissue in different pathological conditions, namely, pre-cancer (dysplasia) and cancer (adenocarcinoma), are presented. The values and variation ranges of statistical (moments of the first - fourth order), correlation (excess-autocorrelation functions), and fractal (slopes of approximating curves and dispersion of extrema of logarithmic dependences of power spectra) parameters of the CDMA coordinate distributions are studied. Objective criteria for pathology diagnostics and differentiation of its severity degree are determined. (image processing)

Ushenko, Yu A; Gorskii, M P; Dubolazov, A V; Motrich, A V; Ushenko, V A; Sidor, M I [Yuriy Fedkovych Chernivtsi National University, Chernivtsi (Ukraine)

2012-08-31

335

An antidynamo theorem for spherically symmetric generation-diffusion conditions  

NASA Astrophysics Data System (ADS)

We consider a mean magnetic induction field B evolving in an electrically conducting turbulently convecting fluid sphere V, where gravity acting radially is the only force imposing order. The turbulence is radially stratified and mirror-symmetric about planes through the origin. The only possible mean flow is spherically symmetric and radial. For small-scale turbulence, a large-scale mean field emf is generated that to a good approximation is linear in B and VB. This emf comprises the spherically symmetric 1, 2, 1 and r1 effects of Rädler (1980). In combination with the molecular magnetic diffusivity ?m, these effects produce anisotropic diffusion, different for poloidal S and toroidal T magnetic fields, and characterised by generalised diffusion coefficients ?i(i = 0, 1, 2). The ?1 and ?r1 effects also produce field generation similar to induction by a radial compressible laminar flow or equivalent (e.g. thermomagnetic) effect. Reasoning that usually ?i > 0, we prove decay of the norms max|r2Br| and ||T/r|| 1,v. For each of these norms, we give a bounding function that decays exponentially with a prescribed decay rate. Furthermore, the decay of each norm is strictly monotonic, regardless of time variations in the generation or diffusion terms. We infer that a self-exciting mean field dynamo cannot persist unless some mechanism, such as rotation, is present to break either the spherical or mirror symmetry of the turbulence. For low conductivity (large ?m) or strong turbulence (large ?1), and relatively weak anisotropy (smaller ?2, ?r1) the decay occurs on the total diffusion time-scale determined by ?m + ?1 In stars where ?;1 probably dominates, the decay is therefore very fast on the molecular diffusion time-scale. In such cases rotation is an obvious choice for symmetry-breaker, and possible field maintenance. The results herein extend the earlier result of Reichert (1982), who proved that the magnetic energy decays in some non-specific not necessarily monotonic fashion, assuming ?m, ?1, ?2, ?1 and ?r1 to be time-independent. Allowance for non-steady conditions as herein, necessitates a very different method of proof. As a special case, our results strengthen the already established Radial Velocity Theorem [references in Ivers and James (1986)], by supplying more rigour and faster decaying bounds.

Ivers, D. J.; James, R. W.

336

Substrate protein switches GroE chaperonins from asymmetric to symmetric cycling by catalyzing nucleotide exchange.  

PubMed

The complex kinetics of Pi and ADP release by the chaperonin GroEL/GroES is influenced by the presence of unfolded substrate protein (SP). Without SP, the kinetics of Pi release are described by four phases: a "lag," a "burst" of ATP hydrolysis by the nascent cis ring, a "delay" caused by ADP release from the nascent trans ring, and steady-state ATP hydrolysis. The release of Pi precedes the release of ADP. The rate-determining step of the asymmetric cycle is the release of ADP from the trans ring of the GroEL-GroES1 "bullet" complex that is, consequently, the predominant species. In the asymmetric cycle, the two rings of GroEL function alternately, 180° out of phase. In the presence of SP, a change in the kinetic mechanism occurs. With SP present, the kinetics of ADP release are also described by four phases: a lag, a "surge" of ADP release attributable to SP-induced ADP/ATP exchange, and a "pause" during which symmetrical "football" particles are formed, followed by steady-state ATP hydrolysis. SP catalyzes ADP/ATP exchange on the trans ring. Now ADP release precedes the release of Pi, and the rate-determining step of the symmetric cycle becomes the hydrolysis of ATP by the symmetric GroEL-GroES2 football complex that is, consequently, the predominant species. A FRET-based analysis confirms that asymmetric GroEL-GroES1 bullets predominate in the absence of SP, whereas symmetric GroEL-GroES2 footballs predominate in the presence of SP. This evidence suggests that symmetrical football particles are the folding functional form of the chaperonin machine in vivo. PMID:24167257

Ye, Xiang; Lorimer, George H

2013-11-12

337

Optical Linear Polarimetry of Ultra Cool Dwarfs  

E-print Network

Optical linear polarimetry of 8 ultra cool field dwarfs, with spectral types ranging from M9 to L8, is presented. The linear polarisation, P, of each dwarf we measured is P < 0.2%. Three dwarfs have polarisations compatible with zero, two are marginal detections, and three have significant polarisation. Due to their small distance, an insterstellar origin for the detected polarisation can be safely ruled out. Our detections confirm that dust is present in the atmosphere of these brown dwarfs and that the scattering geometry is not symmetric. Possibilities for asymmetry include the dwarfs rotating rapidly and being oblate, or the cloud coverage in the atmosphere being inhomogenous.

Francois Menard; Xavier Delfosse; Jean-Louis Monin

2002-11-14

338

Partially PT symmetric optical potentials with all-real spectra and soliton families in multidimensions.  

PubMed

Multidimensional complex optical potentials with partial parity-time (PT) symmetry are proposed. The usual PT symmetry requires that the potential is invariant under complex conjugation and simultaneous reflection in all spatial directions. However, we show that if the potential is only partially PT symmetric, i.e., it is invariant under complex conjugation and reflection in a single spatial direction, then it can also possess all-real spectra and continuous families of solitons. These results are established analytically and corroborated numerically. PMID:24690689

Yang, Jianke

2014-03-01

339

Linear metal-metal-bonded tetranuclear M-Mo-Mo-M complexes (M = Ir and Rh): oxidative metal-metal bond formation in a tetrametallic system and 1,4-addition reaction of alkyl halides.  

PubMed

Reaction of Mo2(pyphos)4 (1) with [MCl(CO)2]2 (M = Ir and Rh) afforded linear tetranuclear complexes of a formula Mo2M2(CO)2(Cl)2(pyphos)4 (2, M = Ir; 3, M = Rh). X-ray diffraction studies confirmed that two "MCl(CO)" fragments are introduced into both axial sites of the Mo2 core in 1 and coordinated by two PPh2 groups in a trans fashion, thereby forming a square-planar geometry around each M(I) metal. Treatment of 2 and 3 with an excess amount of tBuNC and XylNC induced dissociation of the carbonyl and chloride ligands to yield the corresponding dicationic complexes [Mo2M2(pyphos)4(tBuNC)4](Cl)2 (5a, M = Ir; 6a, M = Rh) and [Mo2M2(pyphos)4(XylNC)4](Cl)2 (7, M = Ir; 8, M = Rh). Their molecular structures were characterized by spectroscopic data as well as X-ray diffraction studies of BPh4 derivatives [Mo2M2(pyphos)4(tBuNC)4](BPh4)2 (5b, M = Ir; 6c, M = Rh), which confirmed that there is no direct sigma-bonding interaction between the M(I) atom and the Mo2 core. The M(I) atom in 5 and 6 can be oxidized by either 2 equiv of [Cp2Fe][PF6] or an equimolar amount of I2 to afford Mo(II)2M(II)2 complexes, [Mo2M2(X)2(tBuNC)4(pyphos)4]2+ in which two Mo-M(II) single bonds are formed and the bond order of the Mo-Mo moiety has been decreased to three. The Ir(I) complex 5a reacted not only with methyl iodide but also with dichloromethane to afford the 1,4-oxidative addition products [Mo2Ir2(CH3)(I)(tBuNC)4(pyphos)4](Cl)2 (13) and [Mo2Ir2(CH2Cl)(Cl)(tBuNC)4(pyphos)4](Cl)2 (15), respectively, although the corresponding reactions using the Rh(I) analogue 6 did not proceed. Kinetic analysis of the reaction with CH3I suggested that the 1,4-oxidative addition to the Ir(I) complex occurs in an SN2 reaction mechanism. PMID:17608413

Ohashi, Masato; Shima, Asuka; Rüffer, Tobias; Mizomoto, Hitoshi; Kaneda, Yutaka; Mashima, Kazushi

2007-08-01

340

An Approximate Solution and Master Curves for Buckling of Symmetrically Laminated Composite Cylinders  

NASA Technical Reports Server (NTRS)

Nondimensional linear-bifurcation buckling equations for balanced, symmetrically laminated cylinders with negligible shell-wall anisotropies and subjected to uniform axial compression loads are presented. These equations are solved exactly for the practical case of simply supported ends. Nondimensional quantities are used to characterize the buckling behavior that consist of a stiffness-weighted length-to-radius parameter, a stiffness-weighted shell-thinness parameter, a shell-wall nonhomogeneity parameter, two orthotropy parameters, and a nondimensional buckling load. Ranges for the nondimensional parameters are established that encompass a wide range of laminated-wall constructions and numerous generic plots of nondimensional buckling load versus a stiffness-weighted length-to-radius ratio are presented for various combinations of the other parameters. These plots are expected to include many practical cases of interest to designers. Additionally, these plots show how the parameter values affect the distribution and size of the festoons forming each response curve and how they affect the attenuation of each response curve to the corresponding solution for an infinitely long cylinder. To aid in preliminary design studies, approximate formulas for the nondimensional buckling load are derived, and validated against the corresponding exact solution, that give the attenuated buckling response of an infinitely long cylinder in terms of the nondimensional parameters presented herein. A relatively small number of "master curves" are identified that give a nondimensional measure of the buckling load of an infinitely long cylinder as a function of the orthotropy and wall inhomogeneity parameters. These curves reduce greatly the complexity of the design-variable space as compared to representations that use dimensional quantities as design variables. As a result of their inherent simplicity, these master curves are anticipated to be useful in the ongoing development of buckling-design technology.

Nemeth, Michael P.

2013-01-01

341

Expanding symmetric multiprocessor capability through gang scheduling  

SciTech Connect

Symmetric Multiprocessor (SMP) systems normally provide both space- sharing and time-sharing to insure high system utilization and good responsiveness. However the prevailing lack of concurrent scheduling for parallel programs precludes SMP use in addressing many large-scale problems. Tightly synchronized communications are impractical and normal time-sharing reduces the benefit of cache memory. Evidence gathered at Lawrence Livermore National Laboratory (LLNL) indicates that gang scheduling can increase the capability of SMP systems and parallel program performance without adverse impact upon system utilization or responsiveness.

Jette, M.A.

1998-03-01

342

Entanglement and symmetry in permutation symmetric states  

E-print Network

We investigate the relationship between multipartite entanglement and symmetry, focusing on permutation symmetric states. We use the Majorana representation, where these states correspond to points on a sphere. Symmetry of the representation under rotation is equivalent to symmetry of the states under products of local unitaries. The geometric measure of entanglement is thus phrased entirely as a geometric optimisation, and a condition for the equivalence of entanglement measures written in terms of point symmetries. Finally we see that different symmetries of the states correspond to different types of entanglement with respect to SLOCC interconvertibility.

Damian J. H. Markham

2010-01-03

343

Matter Collineations of Plane Symmetric Spacetimes  

E-print Network

This paper is devoted to the study of matter collineations of plane symmetric spacetimes (for a particular class of spacetimes) when the energy-momentum tensor is non-degenerate. There exists many interesting cases where we obtain proper matter collineations. The matter collineations in these cases are {\\it four}, \\emph{five}, {\\it six}, \\emph{seven} and {\\it ten} with some constraints on the energy-momentum tensor. We have solved some of these constraints to obtain solutions of the Einstein field equations.

M. Sharif; Nousheen Ilyas

2008-09-09

344

Chaos in symmetric phase oscillator networks.  

PubMed

Phase-coupled oscillators serve as paradigmatic models of networks of weakly interacting oscillatory units in physics and biology. The order parameter which quantifies synchronization so far has been found to be chaotic only in systems with inhomogeneities. Here we show that even symmetric systems of identical oscillators may not only exhibit chaotic dynamics, but also chaotically fluctuating order parameters. Our findings imply that neither inhomogeneities nor amplitude variations are necessary to obtain chaos; i.e., nonlinear interactions of phases give rise to the necessary instabilities. PMID:22243002

Bick, Christian; Timme, Marc; Paulikat, Danilo; Rathlev, Dirk; Ashwin, Peter

2011-12-01

345

Quantum exchange interaction of spherically symmetric plasmoids  

E-print Network

We study nano-sized spherically symmetric plasma structures which are radial nonlinear oscillations of electrons in plasma. The effective interaction of these plasmoids via quantum exchange forces between ions is described. We calculate the energy of this interaction for the realistic case of an atmospheric plasma. The conditions when the exchange interaction is attractive are examined and it is shown that separate plasmoids can form a single object. The application of our results to the theoretical description of stable atmospheric plasma structures is considered.

Dvornikov, Maxim

2011-01-01

346

Single mode PT symmetric large area lasers  

NASA Astrophysics Data System (ADS)

We experimentally demonstrate single longitudinal mode operation in microring laser using the concept of PT symmetry. A PT-symmetric coupled resonator arrangement can considerably enhance the maximum achievable gain of single mode microring cavity. The method is broadband thus work well for inhomogenously broadened gain mediums. It doesn't rely on any additional component to ensure its mode selective performance, and it is robust with respect to fabrication inaccuracies. This result may pave the way for a novel way of designing integrated laser sources based on PT symmetry.

Hodaei, Hossein; Miri, Mohammad-Ali; Heinrich, Matthias; Christodoulides, Demetrios N.; Khajavikhan, Mercedeh

2014-09-01

347

Communities and classes in symmetric fractals  

E-print Network

Two aspects of fractal networks are considered: the community structure and the class structure, where classes of nodes appear as a consequence of a local symmetry of nodes. The analysed systems are the networks constructed for two selected symmetric fractals: the Sierpinski triangle and the Koch curve. Communities are searched for by means of a set of differential equations. Overlapping nodes which belong to two different communities are identified by adding some noise to the initial connectivity matrix. Then, a node can be characterized by a spectrum of probabilities of belonging to different communities. Our main goal is that the overlapping nodes with the same spectra belong to the same class.

Krawczyk, M J

2014-01-01

348

An accurate Fourier splitting scheme for solving the cubic quintic complex Ginzburg-Landau equation  

NASA Astrophysics Data System (ADS)

In this paper, we present a splitting scheme for the pseudo-spectral numerical method namely the Split-Step Fourier method (SSFM), in our approach we expand the exponential term in a manner that a succession of linear and nonlinear terms are distributed uniformly along one step size, the splitting will be performed symmetrically, this new scheme will be tested on one of the most used nonlinear partial deferential equation in optics, namely the cubic quintic complex Ginzburg-Landau (CQCGL) equation, in this work we demonstrate that the accuracy of the Split Step Fourier method scheme can be improved by expanding and distributing it in small parts within one step.

Mohammedi, Tidjani; Aissat, Abdelkader

2014-11-01

349

PT-symmetric sine-Gordon breathers  

NASA Astrophysics Data System (ADS)

In this work, we explore a prototypical example of a genuine continuum breather (i.e., not a standing wave) and the conditions under which it can persist in a PT-symmetric medium. As our model of interest, we will explore the sine-Gordon equation in the presence of a PT-symmetric perturbation. Our main finding is that the breather of the sine-Gordon model will only persist at the interface between gain and loss that PT-symmetry imposes but will not be preserved if centered at the lossy or at the gain side. The latter dynamics is found to be interesting in its own right giving rise to kink–antikink pairs on the gain side and complete decay of the breather on the lossy side. Lastly, the stability of the breathers centered at the interface is studied. As may be anticipated on the basis of their ‘delicate’ existence properties such breathers are found to be destabilized through a Hopf bifurcation in the corresponding Floquet analysis.

Lu, Nan; Kevrekidis, Panayotis G.; Cuevas-Maraver, Jesús

2014-11-01

350

Compressible flow about symmetrical Joukowski profiles  

NASA Technical Reports Server (NTRS)

The method of Poggi is employed for the determination of the effects of compressibility upon the flow past an obstacle. A general expression for the velocity increment due to compressibility is obtained. The general result holds whatever the shape of the obstacle; but, in order to obtain the complete solution, it is necessary to know a certain Fourier expansion of the square of the velocity of flow past the obstacle. An application is made to the case flow of a symmetrical Joukowski profile with a sharp trailing edge, fixed in a stream of an arbitrary angle of attack and with the circulation determined by the Kutta condition. The results are obtained in a closed form and are exact insofar as the second approximation to the compressible flow is concerned, the first approximation being the result for the corresponding incompressible flow. Formulas for lift and moment analogous to the Blasius formulas in incompressible flow are developed and are applied to thin symmetrical Joukowski profiles for small angles of attack.

Kaplan, Carl

1938-01-01

351

Analysis of non-symmetrical flapping airfoils  

NASA Astrophysics Data System (ADS)

Simulations have been done to assess the lift, thrust and propulsive efficiency of different types of non-symmetrical airfoils under different flapping configurations. The variables involved are reduced frequency, Strouhal number, pitch amplitude and phase angle. In order to analyze the variables more efficiently, the design of experiments using the response surface methodology is applied. Results show that both the variables and shape of the airfoil have a profound effect on the lift, thrust, and efficiency. By using non-symmetrical airfoils, average lift coefficient as high as 2.23 can be obtained. The average thrust coefficient and efficiency also reach high values of 2.53 and 0.61, respectively. The lift production is highly dependent on the airfoil’s shape while thrust production is influenced more heavily by the variables. Efficiency falls somewhere in between. Two-factor interactions are found to exist among the variables. This shows that it is not sufficient to analyze each variable individually. Vorticity diagrams are analyzed to explain the results obtained. Overall, the S1020 airfoil is able to provide relatively good efficiency and at the same time generate high thrust and lift force. These results aid in the design of a better ornithopter’s wing.

Tay, W. B.; Lim, K. B.

2009-08-01

352

Local and Global Stability ofLocal and Global Stability of Symmetric HeterogeneouslySymmetric Heterogeneously--  

E-print Network

Symmetric Heterogeneously-- Delayed Control SystemsDelayed Control Systems Yueping Zhang and Dmitri Loguinov Department heterogeneous delay: ­ Each flow has a different RTT equal to time units ­ Metric can be fixed for each flow or changing over time (i.e., random) #12;5 · Not only are real Internet delays heterogeneous, they are also

Loguinov, Dmitri

353

Design and Synthesis of C2-Symmetric N-Heterocyclic Carbene Precursors and Metal Carbenoids  

PubMed Central

Chiral, C2-symmetric imidazolium and imidazolinium ions, as well as the corresponding copper or silver bound carbenoids, have been prepared. Structural study of these compounds by X-ray crystallography reveals a chiral pocket that surrounds the putative carbene site or the metal-carbene bond, at carbon 2, in three of the four ligands prepared. Preliminary investigation into the application of these complexes has shown one of them to be highly enantioselective in the hydrosilylation of acetophenone. PMID:21823580

Albright, Abigail; Eddings, Daniel; Black, Regina; Welch, Christopher J.; Gerasimchuk, Nikolay N.; Gawley, Robert E.

2011-01-01

354

Symmetry-restrained flexible fitting for symmetric EM maps  

PubMed Central

Summary Many large biological macromolecules have inherent structural symmetry, being composed of a few distinct subunits, repeated in a symmetric array. These complexes are often not amenable to traditional high-resolution structural determination methods, but can be imaged in functionally relevant states using cryo-electron microscopy (cryo-EM). A number of methods for fitting atomic-scale structures into cryo-EM maps have been developed, including the molecular dynamics flexible fitting (MDFF) method. However, quality and resolution of the cryo-EM map are the major determinants of a method’s success. In order to incorporate knowledge of structural symmetry into the fitting procedure, we developed the symmetry-restrained MDFF method. The new method adds to the cryo-EM map-derived potential further restraints on the allowed conformations of a complex during fitting, thereby improving the quality of the resultant structure. The benefit of using symmetry-based restraints during fitting, particularly for medium to low-resolution data, is demonstrated for three different systems. PMID:21893283

Chan, Kwok-Yan; Gumbart, James; McGreevy, Ryan; Watermeyer, Jean M.; Sewell, B. Trevor; Schulten, Klaus

2011-01-01

355

Transition metal complexes with the C 1-symmetric diphosphines ( R)-( R)-3-benzyl-2,4-bis(diphenylphosphino)pentane and ( R)-( R)-3-benzyl( p-sulphonate)-2,4-bis(diphenylphosphino)pentane sodium salt. Applications to enantioselective catalysis in different phase systems  

Microsoft Academic Search

The C1-symmetric diphosphine (R)-(R)-3-benzyl-2,4-bis(diphenylphosphino)pentane [(R)-(R)-BDPBzP] has been employed, in combination with Ru(II), Rh(I), Ir(I) and Pd(II) ions, in a variety of homogeneous asymmetric reactions spanning from the hydrogenation of dimethyl itaconate, methyl 2-acetamidocinnamate, 2-methylquinoxaline, methyl pyruvate and dihydro-4,4-dimethyl-2,3-furandione, to the hydroboration of styrene, to the allylic alkylation of (rac)-(E)-3-acetoxy-1,3-diphenyl-1-propene with dimethyl malonate. The aqueous-biphase hydrogenation of dimethyl itaconate has been

Claudio Bianchini; Pierluigi Barbaro; Giancarlo Scapacci

2001-01-01

356

Group Lifting Structures For Multirate Filter Banks, II: Linear Phase Filter Banks  

SciTech Connect

The theory of group lifting structures is applied to linear phase lifting factorizations for the two nontrivial classes of two-channel linear phase perfect reconstruction filter banks, the whole-and half-sample symmetric classes. Group lifting structures defined for the reversible and irreversible classes of whole-and half-sample symmetric filter banks are shown to satisfy the hypotheses of the uniqueness theorem for group lifting structures. It follows that linear phase lifting factorizations of whole-and half-sample symmetric filter banks are therefore independent of the factorization methods used to compute them. These results cover the specification of user-defined whole-sample symmetric filter banks in Part 2 of the ISO JPEG 2000 standard.

Brislawn, Christopher M [Los Alamos National Laboratory

2008-01-01

357

Exact quantization of a PT-symmetric (reversible) Liénard-type nonlinear oscillator  

NASA Astrophysics Data System (ADS)

We carry out an exact quantization of a PT-symmetric (reversible) Liénard-type one-dimensional nonlinear oscillator both semiclassically and quantum mechanically. The associated time-independent classical Hamiltonian is of nonstandard type and is invariant under a combined coordinate reflection and time reversal transformation. We use the von Roos symmetric ordering procedure to write down the appropriate quantum Hamiltonian. While the quantum problem cannot be tackled in coordinate space, we show how the problem can be successfully solved in momentum space by solving the underlying Schrödinger equation therein. We explicitly obtain the eigenvalues and eigenfunctions (in momentum space) and deduce the remarkable result that the spectrum agrees exactly with that of the linear harmonic oscillator, which is also confirmed by a semiclassical modified Bohr-Sommerfeld quantization rule, while the eigenfunctions are completely different.

Chithiika Ruby, V.; Senthilvelan, M.; Lakshmanan, M.

2012-09-01

358

Categorical Glueing and Logical Predicates for Models of Linear Logic  

E-print Network

Categorical Glueing and Logical Predicates for Models of Linear Logic Masahito Hasegawa Research Abstract We give a series of glueing constructions for categorical models of fragments of lin- ear logic. Specifically, we consider the glueing of (i) symmetric monoidal closed cat- egories (models of Multiplicative

Hasegawa, Masahito

359

Shrink-Wrapping trajectories for Linear Programming - Optimization ...  

E-print Network

May 30, 2010 ... The elementary symmetric polynomials in the example above play an ...... with a system of orthonormal coordinates where the first coordinate axis is aligned with ...... that the composite k-linear operator f?(z)?1f(k)(z) acting on a fixed k-tuple ? ..... short-step method would typically fail due to round-off errors.

2010-05-30

360

A non linear ADC for sensor linearization  

Microsoft Academic Search

A successive approximation ADC with nonlinear characteristic is presented as an effective method for sensor linearization. Drastic simplification of the ADC structure was obtained by implementing a piece wise linear approximation of the required non linear curve. The design and simulated performance of an 8-bit prototype, applied to the linearization of a real flow sensor, are presented.

Emilio Volpi; Nicolò Nizza; Paolo Bruschi

2007-01-01

361

Effects of the Chain Architecture on the Miscibility of Symmetric Linear/Linear and Star/Star Polymer Blends  

E-print Network

and molecular weights causes changes in the phase diagram due to shielding in the core region.1,2 Neighboring of monomers in the core is high. The extent of the changes in the phase diagram would be expected to vary in the blend. The one-loop diagrams that describe the two-point correlations between Gaussian chains

Theodorakis, Panagiotis E.

362

Complexity and Relations  

ERIC Educational Resources Information Center

A central feature of complexity is that it is based on non-linear, recursive relations. However, in most current accounts of complexity such relations, while non-linear, are based on the reductive relations of a Newtonian onto-epistemological framework. This means that the systems that are emergent from the workings of such relations are a…

Lancaster, Jeanette Elizabeth

2013-01-01

363

Symmetric instability in the Gulf Stream  

NASA Astrophysics Data System (ADS)

Analyses of wintertime surveys of the Gulf Stream (GS) conducted as part of the CLIvar MOde water Dynamic Experiment (CLIMODE) reveal that water with negative potential vorticity (PV) is commonly found within the surface boundary layer (SBL) of the current. The lowest values of PV are found within the North Wall of the GS on the isopycnal layer occupied by Eighteen Degree Water, suggesting that processes within the GS may contribute to the formation of this low-PV water mass. In spite of large heat loss, the generation of negative PV was primarily attributable to cross-front advection of dense water over light by Ekman flow driven by winds with a down-front component. Beneath a critical depth, the SBL was stably stratified yet the PV remained negative due to the strong baroclinicity of the current, suggesting that the flow was symmetrically unstable. A large eddy simulation configured with forcing and flow parameters based on the observations confirms that the observed structure of the SBL is consistent with the dynamics of symmetric instability (SI) forced by wind and surface cooling. The simulation shows that both strong turbulence and vertical gradients in density, momentum, and tracers coexist in the SBL of symmetrically unstable fronts. SI is a shear instability that draws its energy from geostrophic flows. A parameterization for the rate of kinetic energy (KE) extraction by SI applied to the observations suggests that SI could result in a net dissipation of 33 mW m-2 and 1 mW m-2 for surveys with strong and weak fronts, respectively. The surveys also showed signs of baroclinic instability (BCI) in the SBL, namely thermally direct vertical circulations that advect biomass and PV. The vertical circulation was inferred using the omega equation and used to estimate the rate of release of available potential energy (APE) by BCI. The rate of APE release was found to be comparable in magnitude to the net dissipation associated with SI. This result points to an energy pathway where the GS's reservoir of APE is drained by BCI, converted to KE, and then dissipated by SI and its secondary instabilities. Similar dynamics are likely to be found at other strong fronts forced by winds and/or cooling and could play an important role in the energy balance of the ocean circulation.

Thomas, Leif N.; Taylor, John R.; Ferrari, Raffaele; Joyce, Terrence M.

2013-07-01

364

UNREDUCED SYMMETRIC KKT SYSTEMS ARISING FROM ...  

E-print Network

May 16, 2014 ... programming problems in standard form by Interior Point methods. ... order methods, a linear algebra phase constitutes their computational core and its ... unsymmetric 3 × 3 matrix and block elimination, it is common to use a ...

2014-05-16

365

Local Polynomial Regression for Symmetric Positive Definite Matrices.  

PubMed

Local polynomial regression has received extensive attention for the nonparametric estimation of regression functions when both the response and the covariate are in Euclidean space. However, little has been done when the response is in a Riemannian manifold. We develop an intrinsic local polynomial regression estimate for the analysis of symmetric positive definite (SPD) matrices as responses that lie in a Riemannian manifold with covariate in Euclidean space. The primary motivation and application of the proposed methodology is in computer vision and medical imaging. We examine two commonly used metrics, including the trace metric and the Log-Euclidean metric on the space of SPD matrices. For each metric, we develop a cross-validation bandwidth selection method, derive the asymptotic bias, variance, and normality of the intrinsic local constant and local linear estimators, and compare their asymptotic mean square errors. Simulation studies are further used to compare the estimators under the two metrics and to examine their finite sample performance. We use our method to detect diagnostic differences between diffusion tensors along fiber tracts in a study of human immunodeficiency virus. PMID:23008683

Yuan, Ying; Zhu, Hongtu; Lin, Weili; Marron, J S

2012-09-01

366

Nonlinear coupling of tearing fluctuations in the Madison Symmetric Torus  

SciTech Connect

Three-wave, nonlinear, tearing mode coupling has been measured in the Madison Symmetric Torus (MST) reversed-field pinch (RFP) [Fusion Technol. 19, 131 (1991)] using bispectral analysis of edge magnetic fluctuations resolved in k-space. The strength of nonlinear three-wave interactions satisfying the sum rules m[sub 1] + m[sub 2] = m[sub 3] and n[sub 1] + n[sub 2] = n[sub 3] is measured by the bicoherency. In the RFP, m=l, n[approximately]2R/a (6 for MST) internally resonant modes are linearly unstable and grow to large amplitude. Large values of bicoherency occur for two m=l modes coupled to an m=2 mode and the coupling of intermediate toroidal modes, e.g., n=6 and 7 coupled to n=13. These experimental bispectral features agree with predicted bispectral features derived from MHD computation. However, in the experiment, enhanced coupling occurs in the crash'' phase of a sawtooth oscillation concomitant with a broadened mode spectrum suggesting the onset of a nonlinear cascade.

Sarff, J.S.; Almagri, A.F.; Cekic, M.; Den Hartog, D.J.; Fiksel, G.; Hokin, S.A.; Ji, H.; Prager, S.C.; Shen, W.; Stoneking, M.R. (Wisconsin Univ., Madison, WI (United States)); Assadi, S. (Fermi National Accelerator Lab., Batavia, IL (United States)); Sidikman, K.L. (Oak Ridge National Lab., TN (United States))

1992-11-01

367

Nonlinear coupling of tearing fluctuations in the Madison Symmetric Torus  

SciTech Connect

Three-wave, nonlinear, tearing mode coupling has been measured in the Madison Symmetric Torus (MST) reversed-field pinch (RFP) [Fusion Technol. 19, 131 (1991)] using bispectral analysis of edge magnetic fluctuations resolved in ``k-space. The strength of nonlinear three-wave interactions satisfying the sum rules m{sub 1} + m{sub 2} = m{sub 3} and n{sub 1} + n{sub 2} = n{sub 3} is measured by the bicoherency. In the RFP, m=l, n{approximately}2R/a (6 for MST) internally resonant modes are linearly unstable and grow to large amplitude. Large values of bicoherency occur for two m=l modes coupled to an m=2 mode and the coupling of intermediate toroidal modes, e.g., n=6 and 7 coupled to n=13. These experimental bispectral features agree with predicted bispectral features derived from MHD computation. However, in the experiment, enhanced coupling occurs in the ``crash`` phase of a sawtooth oscillation concomitant with a broadened mode spectrum suggesting the onset of a nonlinear cascade.

Sarff, J.S.; Almagri, A.F.; Cekic, M.; Den Hartog, D.J.; Fiksel, G.; Hokin, S.A.; Ji, H.; Prager, S.C.; Shen, W.; Stoneking, M.R. [Wisconsin Univ., Madison, WI (United States); Assadi, S. [Fermi National Accelerator Lab., Batavia, IL (United States); Sidikman, K.L. [Oak Ridge National Lab., TN (United States)

1992-11-01

368

Concrete Representation and Separability Criteria for Symmetric Quantum State  

NASA Astrophysics Data System (ADS)

Using the typical generators of the special unitary groups S U(2), the concrete representation of symmetric quantum state is established, then the relations satisfied by those coefficients in the representation are presented. Based on the representation of density matrix, the PPT criterion and CCNR criterion are proved to be equivalent on judging the separability of symmetric quantum states. Moreover, it is showed that the matrix ? ? of symmetric quantum state only has five efficient entries, thus the calculation of ?? ? ? is simplified. Finally, the quantitative expressions of real symmetric quantum state under the ?? ? ? separability criterion are obtained.

Li, Chang'e.; Tao, Yuanhong; Zhang, Jun; Li, Linsong; Nan, Hua

2014-09-01

369

On the structure of symmetric self-dual Lie algebras  

NASA Astrophysics Data System (ADS)

A finite-dimensional Lie algebra is called (symmetric) self-dual, if it possesses an invariant nondegenerate (symmetric) bilinear form. Symmetric self-dual Lie algebras have been studied by Medina and Revoy, who have proven a very useful theorem about their structure. In this paper we prove a refinement of their theorem that has wide applicability in conformal field theory, where symmetric self-dual Lie algebras start to play an important role due to the fact that they are precisely the Lie algebras that admit a Sugawara construction. We also prove a few corollaries that are important in conformal field theory.

Figueroa-O'Farrill, José M.; Stanciu, Sonia

1996-08-01

370

The Symmetrization Method in Problems on Nonoverlapping Domains  

NASA Astrophysics Data System (ADS)

A new approach to the use of symmetrization is considered. Sterner symmetrization is taken as the main tool. An arbitrary symmetrization transformation connected with a given quadratic differential \\mathcal{Q}(z)\\,dz^2 is obtained by successive application of the mapping \\zeta=\\int \\mathcal{Q}^{1/2}(z)\\,dz and Steiner symmetrization. As a consequence of the main theorem, the corresponding results of Lavrent'ev, Goluzin, Jenkins, and others are refined and generalized to the case of domains of arbitrary connectivity (not necessarily having a filling).Bibliography: 21 titles.

Dubinin, V. N.

1987-02-01

371

Geometric inequalities for axially symmetric black holes  

E-print Network

A geometric inequality in General Relativity relates quantities that have both a physical interpretation and a geometrical definition. It is well known that the parameters that characterize the Kerr-Newman black hole satisfy several important geometric inequalities. Remarkably enough, some of these inequalities also hold for dynamical black holes. This kind of inequalities play an important role in the characterization of the gravitational collapse, they are closed related with the cosmic censorship conjecture. Axially symmetric black holes are the natural candidates to study these inequalities because the quasi-local angular momentum is well defined for them. We review recent results in this subject and we also describe the main ideas behind the proofs. Finally, a list of relevant open problem is presented.

Sergio Dain

2011-11-15

372

Quantum searches on highly symmetric graphs  

NASA Astrophysics Data System (ADS)

We study scattering quantum walks on highly symmetric graphs and use the walks to solve search problems on these graphs. The particle making the walk resides on the edges of the graph, and at each time step scatters at the vertices. All of the vertices have the same scattering properties except for a subset of special vertices. The object of the search is to find a special vertex. A quantum circuit implementation of these walks is presented in which the set of special vertices is specified by a quantum oracle. We consider the complete graph, a complete bipartite graph, and an M -partite graph. In all cases, the dimension of the Hilbert space in which the time evolution of the walk takes place is small (between three and six), so the walks can be completely analyzed analytically. Such dimensional reduction is due to the fact that these graphs have large automorphism groups. We find the usual quadratic quantum speedups in all cases considered.

Reitzner, Daniel; Hillery, Mark; Feldman, Edgar; Bužek, Vladimír

2009-01-01

373

Cracked shells under skew-symmetric loading  

NASA Technical Reports Server (NTRS)

A shell containing a through crack in one of the principal planes of curvature and under general skew-symmetric loading is considered. By employing a Reissner type shell theory which takes into account the effect of transverse shear strains, all boundary conditions on the crack surfaces are satisfied separately. Consequently, unlike those obtained from the classical shell theory, the angular distributions of the stress components around the crack tips are shown to be identical to the distributions obtained from the plane and antiplane elasticity solutions. Extensive results are given for axially and circumferentially cracked cylindrical shells, spherical shells, and toroidal shells under uniform inplane shearing, out of plane shearing, and torsion. The effect of orthotropy on the results is also studied.

Lelale, F.

1982-01-01

374

Implications of nonlinearity for spherically symmetric accretion  

E-print Network

Stationary solutions of spherically symmetric accretion processes have been subjected to a time-dependent radial perturbation, whose equation includes nonlinearity to any arbitrary order. Regardless of the order of nonlinearity, the equation of the perturbation bears a form that is remarkably similar to the metric equation of an analogue acoustic black hole. Casting the perturbation as a standing wave and maintaining nonlinearity in it up to the second order, brings out the time-dependence of the perturbation in the form of a Lienard system. A dynamical systems analysis of this Lienard system reveals a saddle point in real time, with the implication that instabilities will develop in the accreting system when the perturbation is extended into the nonlinear regime. The instability of initial subsonic states may also adversely affect the temporal evolution of the flow towards a final stable transonic state.

Sen, Sourav

2012-01-01

375

Symmetric Lipofibromatous Hamartoma Affecting Digital Nerves  

PubMed Central

Lipofibromatous hamartoma of the nerve is a benign tumor, which affects the major nerves and their branches in the human body. It is often found in the median nerve of the hand and is commonly associated with macrodactyly, but it is rarely found in the digital nerves at the peripheral level. This tumor is often found in young adults and may go through a self-limiting course. However, operation is indicated when the tumor size is large or when the associated nerve compressive symptoms are present. We have experienced a rare case of lipofibromatous hamartoma that symmetrically involved the volar digital nerves of both index fingers on the ulnar side. With the aid of a microscope, we dissected and removed the tumor as much as possible without sacrificing the nerve. No sensory change occurred in both fingers and no sign of recurrence was observed upon follow-up. PMID:15744823

Jung, Sung-No; Yim, Youngmin

2005-01-01

376

Axially Symmetric Post-Newtonian Stellar Systems  

E-print Network

We introduce a method to obtain self-consistent, axially symmetric, thin disklike stellar models in the first post-Newtonian (1PN) approximation. The models obtained are fully analytical and corresponds to the post-Newtonian generalizations of classical ones. By introducing in the field equations provided by the 1PN approximation a known distribution function (DF) corresponding to a Newtonian model, two fundamental equations determining the 1PN corrections are obtained, which are solved using the Hunter method. The rotation curves of the 1PN-corrected models differs from the classical ones and, for the generalized Kalnajs discs, the 1PN corrections are clearly appreciable with values of the mass and radius of a typical galaxy. On the other hand, the relativistic mass correction can be ignored for all models.

Camilo Akimushkin; Javier Ramos-Caro; Guillermo A. González

2009-10-08

377

Acoustic horizons in axially symmetric relativistic accretion  

E-print Network

Transonic accretion onto astrophysical objects is a unique example of analogue black hole realized in nature. In the framework of acoustic geometry we study axially symmetric accretion and wind of a rotating astrophysical black hole or of a neutron star assuming isentropic flow of a fluid described by a polytropic equation of state. In particular we analyze the causal structure of multitransonic configurations with two sonic points and a shock. Retarded and advanced null curves clearly demonstrate the presence of the acoustic black hole at regular sonic points and of the white hole at the shock. We calculate the analogue surface gravity and the Hawking temperature for the inner and the outer acoustic horizons.

Hrvoje Abraham; Neven Bilic; Tapas K. Das

2005-09-15

378

New VLBA Identifications of Compact Symmetric Objects  

E-print Network

The class of radio sources known as Compact Symmetric Objects (CSOs) is of particular interest in the study of the evolution of radio galaxies. CSOs are thought to be young (probably ~10^4 years), and a very high fraction of them exhibit HI absorption toward the central parsecs. The HI, which is thought to be part of a circumnuclear torus of accreting gas, can be observed using the VLBA with high enough angular resolution to map the velocity field of the gas. This velocity field provides new information on the accretion process in the central engines of these young sources. We have identified 9 new CSOs from radio continuum observations for the VLBA Calibrator Survey, increasing the number of known CSOs by almost 50%.

A. B. Peck; G. B. Taylor

1999-11-16

379

Exact Spherically Symmetric Solutions in Massive Gravity  

E-print Network

A phase of massive gravity free from pathologies can be obtained by coupling the metric to an additional spin-two field. We study the gravitational field produced by a static spherically symmetric body, by finding the exact solution that generalizes the Schwarzschild metric to the case of massive gravity. Besides the usual 1/r term, the main effects of the new spin-two field are a shift of the total mass of the body and the presence of a new power-like term, with sizes determined by the mass and the shape (the radius) of the source. These modifications, being source dependent, give rise to a dynamical violation of the Strong Equivalence Principle. Depending on the details of the coupling of the new field, the power-like term may dominate at large distances or even in the ultraviolet. The effect persists also when the dynamics of the extra field is decoupled.

Z. Berezhiani; D. Comelli; F. Nesti; L. Pilo

2008-03-12

380

Multiphoton states related via linear optics  

NASA Astrophysics Data System (ADS)

We investigate which pure states of n photons in d modes can be transformed into each other via passive linear optics, without postselection. In other words, we study the local unitary (LU) equivalence classes of symmetric many-qudit states. Writing our state as f†|?>, with f† a homogeneous polynomial in the mode creation operators, we propose two sets of LU invariants: spectral invariants, which are the eigenvalues of the operator ff†, and moments, each given by the norm of the symmetric component of a tensor power of the initial state, which can be computed as vacuum expectation values of fk(f†)k. We provide a scheme for experimental measurement of the later, as related to the postselection probability of creating state f†k|?> from k copies of f†|?>.

Migda?, Piotr; Rodríguez-Laguna, Javier; Oszmaniec, Micha?; Lewenstein, Maciej

2014-06-01

381

Non-linear Spectroscopy  

NSDL National Science Digital Library

First, the Wright research group at the University of Wisconsin-Madison presents its research using "narrow frequency distribution of tunable laser sources to gain spectral selectivity in an analytical measurement" (1). Along with a summary of its research and techniques, this website offers a great introduction to the fundamentals of non-linear spectroscopy. The second site describes the Ernest Orlando Lawrence Berkeley National Laboratory's success in observing non-linear spectra from chiral molecules (2). With the help of a pictorial poster, users can understand the complex issues of chiral vibrations and spectra. Next, the Sasada lab at Keio University summarizes its research interests in optical communications (3 ). Visitors can find diagrams illustrating absolute frequency difference measurements and the techniques used in the work. The fourth website describes the Regional Laser and Biomedical Technology Laboratories (RLBL) of the University of Pennsylvania's applications of laser spectroscopy in the biochemical, biophysical, and biomedical fields (4 ). Researchers can find out about using the laboratory's facilities, its technological developments, educational opportunities, and much more. Next, the University of Durham describes its examination of spectroscopy of Rubidium vapor (5). Users can learn about its conclusions that "the standard designation of 'saturation spectroscopy' is a misnomer in multilevel systems where hyperfine pumping can occur." At the sixth site, the Laboratories for Biophysical Dynamics' Nano-Biophotonics group addresses its applications of nanotechnology and non-linear spectroscopy to the biology field (6). Visitors can find synopses of its four main research projects and a list of publications. Lastly, the European Laboratory for Non Linear Spectroscopy (LENS) offers an introduction to its goal "to provide advanced laser and spectroscopic facilities for researchers from European countries and to promote and facilitate the exchange of ideas, scientific techniques, and technical skills" (7). Individuals can fine descriptions of past and upcoming events and seminars, lists of publication, and training and job opportunities.

382

BRAIN TUMOR SEGMENTATION WITH SYMMETRIC TEXTURE AND SYMMETRIC INTENSITY-BASED DECISION FORESTS  

PubMed Central

Accurate automated segmentation of brain tumors in MR images is challenging due to overlapping tissue intensity distributions and amorphous tumor shape. However, a clinically viable solution providing precise quantification of tumor and edema volume would enable better pre-operative planning, treatment monitoring and drug development. Our contributions are threefold. First, we design efficient gradient and LBPTOP based texture features which improve classification accuracy over standard intensity features. Second, we extend our texture and intensity features to symmetric texture and symmetric intensity which further improve the accuracy for all tissue classes. Third, we demonstrate further accuracy enhancement by extending our long range features from 100mm to a full 200mm. We assess our brain segmentation technique on 20 patients in the BraTS 2012 dataset. Impact from each contribution is measured and the combination of all the features is shown to yield state-of-the-art accuracy and speed.

Bianchi, Anthony; Miller, James V.; Tan, Ek Tsoon; Montillo, Albert

2014-01-01

383

PT-Symmetric Extension of the Korteweg-de Vries Equation  

E-print Network

The Korteweg-de Vries equation u_t+uu_x+u_{xxx}=0 is PT symmetric (invariant under space-time reflection). Therefore, it can be generalized and extended into the complex domain in such a way as to preserve the PT symmetry. The result is the family of complex nonlinear wave equations u_t-iu(i u_x)^epsilon+u_{xxx}=0, where epsilon is real. The features of these equations are discussed. Special attention is given to the epsilon=3 equation, for which conservation laws are derived and solitary waves are investigated.

Carl M. Bender; Dorje C. Brody; Junhua Chen; Elisabetta Furlan

2006-10-02

384

Dinuclear complexes containing linear M-F-M [M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II)] bridges: trends in structures, antiferromagnetic superexchange interactions, and spectroscopic properties.  

PubMed

The reaction of M(BF(4))(2)·xH(2)O, where M is Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), with the new ditopic ligand m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene (L(m)*) leads to the formation of monofluoride-bridged dinuclear metallacycles of the formula [M(2)(?-F)(?-L(m)*)(2)](BF(4))(3). The analogous manganese(II) species, [Mn(2)(?-F)(?-L(m)*)(2)](ClO(4))(3), was isolated starting with Mn(ClO(4))(2)·6H(2)O using NaBF(4) as the source of the bridging fluoride. In all of these complexes, the geometry around the metal centers is trigonal bipyramidal, and the fluoride bridges are linear. The (1)H, (13)C, and (19)F NMR spectra of the zinc(II) and cadmium(II) compounds and the (113)Cd NMR of the cadmium(II) compound indicate that the metallacycles retain their structure in acetonitrile and acetone solution. The compounds with M = Mn(II), Fe(II), Co(II), Ni(II), and Cu(II) are antiferromagnetically coupled, although the magnitude of the coupling increases dramatically with the metal as one moves to the right across the periodic table: Mn(II) (-6.7 cm(-1)) < Fe(II) (-16.3 cm(-1)) < Co(II) (-24.1 cm(-1)) < Ni(II) (-39.0 cm(-1)) ? Cu(II) (-322 cm(-1)). High-field EPR spectra of the copper(II) complexes were interpreted using the coupled-spin Hamiltonian with g(x) = 2.150, g(y) = 2.329, g(z) = 2.010, D = 0.173 cm(-1), and E = 0.089 cm(-1). Interpretation of the EPR spectra of the iron(II) and manganese(II) complexes required the spin Hamiltonian using the noncoupled spin operators of two metal ions. The values g(x) = 2.26, g(y) = 2.29, g(z) = 1.99, J = -16.0 cm(-1), D(1) = -9.89 cm(-1), and D(12) = -0.065 cm(-1) were obtained for the iron(II) complex and g(x) = g(y) = g(z) = 2.00, D(1) = -0.3254 cm(-1), E(1) = -0.0153, J = -6.7 cm(-1), and D(12) = 0.0302 cm(-1) were found for the manganese(II) complex. Density functional theory (DFT) calculations of the exchange integrals and the zero-field splitting on manganese(II) and iron(II) ions were performed using the hybrid B3LYP functional in association with the TZVPP basis set, resulting in reasonable agreement with experiment. PMID:23043562

Reger, Daniel L; Pascui, Andrea E; Smith, Mark D; Jezierska, Julia; Ozarowski, Andrew

2012-11-01

385

Psychophysical and physiological responses to lifting symmetrical and asymmetrical loads symmetrically and asymmetrically  

Microsoft Academic Search

Eighteen adult males (mean age 22·6 years, weight 78·6kg and height 176·6cm) participated in a study designed to investigate the effects of symmetrical and asymmetrical lifting on the maximum acceptable weight of lift and the resulting physiological cost. Each subject performed sixty different lifting tasks involving two lifting heights, three lifting frequencies and five containers. For each lifting task, the

ANIL MITAL; HAMID F. FARD

1986-01-01

386

Symmetry matters: photodissociation dynamics of symmetrically versus asymmetrically substituted phenols.  

PubMed

We report a combined experimental (H (Rydberg) atom photofragment translational spectroscopy) and theoretical (ab initio electronic structure and vibronic coupling calculations) study of the effects of symmetry on the photodissociation dynamics of phenols. Ultraviolet photoexcitation to the bound S1((1)??*) state of many phenols leads to some O-H bond fission by tunneling through the barrier under the conical intersection (CI) between the S1 and dissociative S2((1)??*) potential energy surfaces in the R(O-H) stretch coordinate. Careful analysis of the total kinetic energy release spectra of the resulting products shows that the radicals formed following S1 ? S0 excitation of phenol and symmetrically substituted phenols like 4-fluorophenol all carry an odd number of quanta in vibrational mode ?(16a), whereas those deriving from asymmetrically substituted systems like 3-fluorophenol or 4-methoxyphenol do not. This contrasting behavior can be traced back to symmetry. Symmetrically substituted phenols exist in two equivalent rotamers, which interconvert by tunneling through the barrier to OH torsional motion. Their states are thus best considered in the non-rigid G4 molecular symmetry group, wherein radiationless transfer from the S1 to S2 state requires a coupling mode of a2 symmetry. Of the three a2 symmetry parent modes, the out-of-plane ring puckering mode ?(16a) shows much the largest interstate coupling constant in the vicinity of the S1/S2 CI. The nuclear motions associated with ?(16a) are orthogonal to the dissociation coordinate, and are thus retained in the radical products. Introducing asymmetry (even a non-linear substituent in the 4-position) lifts the degeneracy of the rotamers, and lowers the molecular symmetry to Cs. Many more parent motions satisfy the reduced (a'') symmetry requirement to enable S1/S2 coupling, the most effective of which is OH torsion. This motion 'disappears' on O-H bond fission; symmetry thus imposes no restriction to forming radical products with vibrational quantum number v = 0. The present work yields values for the O-H bond strengths in 3-FPhOH and 4-MeOPhOH, and recommends modest revisions to the previously reported O-H bond strengths in other asymmetrically substituted phenols like 3- and 2-methylphenol and 4-hydroxyindole. PMID:24201655

Karsili, Tolga N V; Wenge, Andreas M; Marchetti, Barbara; Ashfold, Michael N R

2014-01-14

387

Complex Systems and Human Complexity in Medicine  

Microsoft Academic Search

Concepts taken from complex systems theory, such as ‘agents’ and ‘attractors’, have been proposed as metaphors in medical practice.This proposal is assessed by a comparison of the notions of complex adaptive systems (CAS) and human complexity. CAS are characterized by the emergence of sophisticated output features of rule-governed non-linear systems. Human complexity is the result of higher mental capacities and

Roger Strand; Guri Rortveit; Edvin Schei

2005-01-01

388

Semi-invariants and Integrals of the Full Symmetric sl(n) Toda Lattice  

E-print Network

We consider the full symmetric version of the Lax operator of the Toda lattice which is known as the full symmetric Toda lattice. The phase space of this system is the generic orbit of the coadjoint action of the Borel subgroup B^+(n) of SL(n,R). This system is integrable. We propose a new method of constructing semi-invariants and integrals of the full symmetric Toda lattice. Using only the Toda equations for the Lax eigenvector matrix we prove the existence of the semi-invariants which are Plucker coordinates in the corresponding projective spaces. Then we use these semi-invariants to construct the integrals. It is known that the full symmetric sl(n) Toda lattice has additional integrals which can be produced by Kostant procedure except for the integrals which can be derived by the chopping procedure. Altogether these integrals constitute a full set of the independent non-involutive integrals. Yet the unsolved complicated technical problem is their explicit derivation since Kostant procedure has crucial computational complexities even for low-rank Lax matrices and is practically unapplicable for higher ranks. Our new approach provides a resolution of this problem and results in simple explicit formulae for the full set of independent semi-invariants and integrals expressed both in terms of the Lax matrix and its eigenvector and eigenvalue matrices of the full symmetric sl(n) Toda lattice without using the chopping and Kostant procedures. We also describe the structure of the additional integrals of motion as functions on the flag space modulo the Toda flows and show how Plucker coordinates of different projective spaces define different families of the additional integrals. In this paper we present detailed proofs of the propositions of [24].

Yu. B. Chernyakov; A. S. Sorin

2013-12-16

389

Solution of the spherically symmetric linear thermoviscoelastic problem in the inertia-free limit  

E-print Network

The coupling between mechanical and thermal properties due to thermal expansion complicates the problem of measuring frequency-dependent thermoviscoelastic properties, in particular for highly viscous liquids. A simplification arises if there is spherical symmetry where - as detailed in the present paper - the thermoviscoelastic problem may be solved analytically in the inertia-free limit, i.e., the limit where the sample is much smaller than the wavelength of sound waves at the frequencies of interest. As for the one-dimensional thermoviscoelastic problem [Christensen et al., Phys. Rev. E 75, 041502 (2007)], the solution is conveniently formulated in terms of the so-called transfer matrix, which directly links to the boundary conditions that can be experimentally controlled. Once the transfer matrix has been calculated, it is fairly easy to deduce the equations describing various experimentally relevant special cases (boundary conditions that are adiabatic, isothermal, isochoric, etc.). In most situations the relevant frequency-dependent specific heat is the longitudinal specific heat, a quantity that is in between the isochoric and isobaric frequency-dependent specific heats.

Tage Christensen; Jeppe C. Dyre

2008-01-28

390

Vibration control of large linear quadratic symmetric systems. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

Some unique properties on a class of the second order lambda matrices were found and applied to determine a damping matrix of the decoupled subsystem in such a way that the damped system would have preassigned eigenvalues without disturbing the stiffness matrix. The resulting system was realized as a time invariant velocity only feedback control system with desired poles. Another approach using optimal control theory was also applied to the decoupled system in such a way that the mode spillover problem could be eliminated. The procedures were tested successfully by numerical examples.

Jeon, G. J.

1983-01-01

391

Constraints on the uncertainties of entangled symmetric qubits  

E-print Network

We derive necessary and sufficient inseparability conditions imposed on the variance matrix of symmetric qubits. These constraints are identified by examining a structural parallelism between continuous variable states and two qubit states. Pairwise entangled symmetric multiqubit states are shown here to obey these constraints. We also bring out an elegant local invariant structure exhibited by our constraints.

A. R. Usha Devi; M. S. Uma; R. Prabhu; A. K. Rajagopal

2006-01-05

392

Progressive symmetric erythrokeratoderma with nephrotic syndrome: Coincidence or new association?  

PubMed Central

Progressive symmetric erythrokeratoderma (PSEK) is a rare genodermatosis with variable inheritance. It is characterized by symmetrical, erythematous, and hyperkeratotic plaques on the extremities. We report a case of a 15-year-old boy with PSEK of autosomal recessive inheritance associated with nephrotic syndrome. PMID:24350023

Sacchidanand, S; Sahana, M. S.; Kamoji, Sushruth G.; Asha, G. S.

2013-01-01

393

Second-order symmetric duality with cone constraints  

NASA Astrophysics Data System (ADS)

Wolfe and Mond-Weir type second-order symmetric duals are formulated and appropriate duality theorems are established under [eta]-bonvexity/[eta]-pseudobonvexity assumptions. This formulation removes several omissions in an earlier second-order primal dual pair introduced by Devi [Symmetric duality for nonlinear programming problems involving [eta]-bonvex functions, European J. Oper. Res. 104 (1998) 615-621].

Gulati, T. R.; Gupta, S. K.; Ahmad, I.

2008-10-01

394

A Bootstrap Model Selection Criterion Based on Kullback's Symmetric Divergence  

E-print Network

A Bootstrap Model Selection Criterion Based on Kullback's Symmetric Divergence Katholieke corrected variant of KIC develop for the purpose of sources separation. Our variant utilizes bootstrapping is assumed by the authors. 1 #12; A BOOTSTRAP MODEL SELECTION CRITERION BASED ON KULLBACK'S SYMMETRIC

395

Reducing symmetric polarization aberrations in a lens by annealing  

Microsoft Academic Search

Radially symmetric retardance was found in antireflection coated, molded aspheric glass lenses by measurement with a Mueller matrix imaging polarimeter. The source of the unexpected polarization aberration is traced to a remarkably symmetric radial stress birefringence in the glass believed to arise during fire-polishing of the surfaces. While annealing the lenses relieves much of the stress birefringence, reducing the retardance

J. Wolfe; R. A. Chipman

2004-01-01

396

Twistor spinors on Lorentzian symmetric spaces August 25, 1999  

E-print Network

(see [Pen67], [PR86], [NW84]). They are related to Killing vector fields in semiTwistor spinors on Lorentzian symmetric spaces Helga Baum August 25, 1999 Abstract An indecomposable Riemannian symmetric space which admits nontrivial twistor spinors has constant sectional

Baum, Helga

397

New spin on Einstein's non-symmetric metric tensor  

E-print Network

A solution to the gravitational field equations based on a non-symmetric metric tensor is examined. Unlike Einstein's interpretation of electromagnetism, or Moffat's generalized gravity, it is shown that the non-symmetric part of the metric tensor is the potential of the spin field. This is in agreement with string theory and provides a natural coupling between gravitation and strings.

Richard T. Hammond

2012-07-21

398

Spherically Symmetric Solution in Bi-metric theory of Gravity  

E-print Network

The possibility of spherically symmetric solutions in bi-metric theory of gravity is examined. It is shown that two possible black hole type solutions exists in the model. Spherically symmetric solution of general theory of relativity is recovered in the absence of the second metric. The result is compared with other bi-metric models as well as general theory of relativity.

Anoop Narayanan P E; P K Suresh

2014-03-27

399

Symmetric designs on Lie algebras and interactions of hamiltonian systems  

Microsoft Academic Search

Nonhamiltonian interaction of hamiltonian systems is considered. Dynamical equations are constructed by use of symmetric designs on Lie algebras. The results of analysis of these equations show that some class of symmetric designs on Lie algebras beyond Jordan ones may be useful for a description of almost periodic, asymptotically periodic, almost asymptotically periodic, and, possibly, more chaotic systems. However, the

Denis V. Juriev; Erwin Schrodinger

1995-01-01

400

CASCADIC MULTILEVEL ALGORITHMS FOR SYMMETRIC SADDLE POINT SYSTEMS  

E-print Network

CASCADIC MULTILEVEL ALGORITHMS FOR SYMMETRIC SADDLE POINT SYSTEMS CONSTANTIN BACUTA Abstract. In this paper, we introduce a multilevel algorithm for ap- proximating variational formulations of symmetric an efficient solver such as the gradient or the conjugate gradient algorithm for inverting a Schur complement

Bacuta, Constantin

401

Spherically Symmetric Space-Time with Two Cosmological Constants  

Microsoft Academic Search

We present the analytic spherically symmetric solution of the Einstein equations, which has de Sitter asymptotics for both r ? 8 and r ? 0. This two-lambda spherically symmetric solution is globally regular. At the range of mass parameter Mcr1 cr2 it has three horizons and describes a neutral black hole whose singularity is replaced by a cosmological constant ?

I. Dymnikova; B. Soltysek

1998-01-01

402

Reciprocal Symmetric Boltzmann Function and Unified Boson-Fermion Statistics  

E-print Network

The differential equation for Boltzmann's function is replaced by the corresponding discrete finite difference equation. The difference equation is, then, symmetrized so that the equation remains invariant when step d is replaced by -d. The solutions of this equation come in Boson-Fermion pairs. Reciprocal symmetric Boltzmann's function, thus, unifies both Bosonic and Fermionic distributions.

Mushfiq Ahmad; Muhammad O. G. Talukder

2007-05-05

403

A symmetric surface micromachined gyroscope with decoupled oscillation modes  

E-print Network

A symmetric surface micromachined gyroscope with decoupled oscillation modes Said Emre Alper Abstract This paper reports a new symmetric gyroscope structure that allows both matched resonant beam design. The gyroscope structure is designed using a standard three-layer polysilicon surface

Akin, Tayfun

404

Sign elements in symmetric groups Jrn B. Olsson  

E-print Network

Sign elements in symmetric groups Jørn B. Olsson Dept. of Mathematical Sciences University of Copenhagen, Denmark Nagoya, September 4, 2008 Jørn B. Olsson Sign elements in symmetric groups #12 definition of sign elements and sign classes in finite groups. Content of talk: · Generalities about group

Takahashi, Ryo

405

Cotton-Type and Joint Invariants for Linear Elliptic Systems  

PubMed Central

Cotton-type invariants for a subclass of a system of two linear elliptic equations, obtainable from a complex base linear elliptic equation, are derived both by spliting of the corresponding complex Cotton invariants of the base complex equation and from the Laplace-type invariants of the system of linear hyperbolic equations equivalent to the system of linear elliptic equations via linear complex transformations of the independent variables. It is shown that Cotton-type invariants derived from these two approaches are identical. Furthermore, Cotton-type and joint invariants for a general system of two linear elliptic equations are also obtained from the Laplace-type and joint invariants for a system of two linear hyperbolic equations equivalent to the system of linear elliptic equations by complex changes of the independent variables. Examples are presented to illustrate the results. PMID:24453871

Aslam, A.; Mahomed, F. M.

2013-01-01

406

Fast axis servo for the fast and precise machining of non-rotational symmetric optics  

NASA Astrophysics Data System (ADS)

A new long range tool servo-fast axis servo is developed, which is used for fabricating the non-rotational symmetric optics surface with millimeters' sag. The mechanism design, motion modeling and development of FAS device were studied. The FAS consists of a linear motor, aerostatic bearings, high-resolution encoder and a motion controller. A control strategy consists of a proportional, integral and derivative (PID) feedback controller and velocity/acceleration feedforward controller is implemented to accommodate the system control performance. Experimental tests have been carried out to verify the performance of the FAS system.

Tian, Fujing; Yin, Ziqiang; Li, Shengyi

2014-08-01

407

An optimal system and invariant solutions of dark energy Models in cylindrically symmetric space-time  

E-print Network

In this paper, we derive some new invariant solutions of dark energy models in cylindrically symmetric space-time. To quantify the deviation of pressure from isotropy, we introduce three different time dependent skewness parameters along the spatial directions. The matter source consists of dark energy which is minimally interact with perfect fluid. We use symmetry analysis method for solving the non-linear partial differential equations (NLPDEs) which is more powerful than the classical methods of solving NLPDEs. The geometrical and kinematical features of the models and the behaviour of the anisotropy of dark energy, are examined in detail.

Anil Kumar Yadav; Ahmad T Ali

2014-05-12

408

Neutrino Self-energy in a Magnetized Charge-symmetric Medium  

SciTech Connect

In this talk we present the calculation of the neutrino self-energy in presence of a magnetized medium. The magnetized medium consists of electrons, positrons, neutrinos and a uniform classical magnetic field. The background magnetic field is assumed to be weak compared to the W-Boson mass as a consequence of which only linear order corrections in the field are included in the W boson propagator. The electron propagator consists all order corrections in the background field. Our calculation is specifically suited for situations where the background plasma may be CP symmetric.

Bravo Garcia, Alberto; Bhattacharya, Kaushik; Sahu, Sarira [Nacional Autonoma de Mexico, Circuito Exterior, C.U., A. Postal 70-543, C.P. 04510 Mexico DF (Mexico)

2008-07-02

409

On spherically symmetric metric satisfying the positive kinetic energy coordinate condition  

E-print Network

Generally speaking, there is a negative kinetic energy term in the Lagrangian of the Einstein-Hilbert action of general relativity; On the other hand, the negative kinetic energy term can be vanished by designating a special coordinate system. For general spherically symmetric metric, the question that seeking special coordinate system that satisfies the positive kinetic energy coordinate condition is referred to solving a linear first-order partial differential equation. And then, we present a metric corresponding to the Reissner-Nordstrom solution that satisfies the positive kinetic energy coordinate condition. Finally, we discuss simply the case of the Tolman metric.

T. Mei

2007-11-02

410

Quantum and electromagnetic propagation with the conjugate symmetric Lanczos method.  

PubMed

The conjugate symmetric Lanczos (CSL) method is introduced for the solution of the time-dependent Schrodinger equation. This remarkably simple and efficient time-domain algorithm is a low-order polynomial expansion of the quantum propagator for time-independent Hamiltonians and derives from the time-reversal symmetry of the Schrodinger equation. The CSL algorithm gives forward solutions by simply complex conjugating backward polynomial expansion coefficients. Interestingly, the expansion coefficients are the same for each uniform time step, a fact that is only spoiled by basis incompleteness and finite precision. This is true for the Krylov basis and, with further investigation, is also found to be true for the Lanczos basis, important for efficient orthogonal projection-based algorithms. The CSL method errors roughly track those of the short iterative Lanczos method while requiring fewer matrix-vector products than the Chebyshev method. With the CSL method, only a few vectors need to be stored at a time, there is no need to estimate the Hamiltonian spectral range, and only matrix-vector and vector-vector products are required. Applications using localized wavelet bases are made to harmonic oscillator and anharmonic Morse oscillator systems as well as electrodynamic pulse propagation using the Hamiltonian form of Maxwell's equations. For gold with a Drude dielectric function, the latter is non-Hermitian, requiring consideration of corrections to the CSL algorithm. PMID:18282024

Acevedo, Ramiro; Lombardini, Richard; Turner, Matthew A; Kinsey, James L; Johnson, Bruce R

2008-02-14

411

SOLVING REDUCED KKT SYSTEMS IN BARRIER METHODS FOR LINEAR AND QUADRATIC PROGRAMMING  

Microsoft Academic Search

In barrier methods for constrained optimization, the main work lies in solv- ing large linear systems Kp = r, where K is symmetric and indefinite. For linear programs, these KKT systems are usually reduced to smaller positive-definite systems AH 1ATq = s, where H is a large principal submatrix of K. These systems can be solved more efficiently, butAH 1AT

Philip E. GILL; Walter MURRAY; Dulce B. PONCELE; Michael A. SAUNDERS

412

Studies on linear multistep algorithm for the orbital integration of artificial Earth satellites  

Microsoft Academic Search

The progress in the author's studies on linear multistep algorithm for the orbital integration of artificial Earth satellites are summarized. Three basic principles are introduced to determine the spurious roots of the eigen-polynomial. Five linear multistep integrators are recommended to use in practice, and they have obvious advantages over both symmetric and Cowell methods by means of their comparisons of

Jihong Xu

1999-01-01

413

PT-symmetric coupler with a coupling defect: soliton interaction with exceptional point.  

PubMed

We study the interaction of a soliton in a parity-time (PT) symmetric coupler which has local perturbation of the coupling constant. This defect does not change the PT-symmetry of the system, but locally can achieve the exceptional point. We found that the symmetric solitons after interaction with the defect either transform into breathers or blow up. The dynamics of antisymmetric solitons are more complex, showing domains of successive broadening of the beam and of the beam splitting in two outward propagating solitons, in addition to the single breather generation and blowup. All the effects are preserved when the coupling strength in the center of the defect deviates from the exceptional point. If the coupling is strong enough, the only observable outcome of the soliton-defect interaction is the generation of the breather. PMID:24978491

Bludov, Yuli V; Hang, Chao; Huang, Guoxiang; Konotop, Vladimir V

2014-06-15

414

LINEAR DIFFUSION Erkut Erdem  

E-print Network

LINEAR DIFFUSION Erkut Erdem Hacettepe University February 24th, 2012 CONTENTS 1 Linear Diffusion 1 2 Appendix - The Calculus of Variations 5 References 6 1 LINEAR DIFFUSION The linear diffusion (heat (noisy) input image and u(x, t) be initialized with u(x, 0) = u0(x) = f (x). Then, the linear diffusion

Erdem, Erkut

415

SL(2,R) duality-symmetric action for electromagnetic theory with electric and magnetic sources  

SciTech Connect

For the SL(2,R) duality-invariant generalization of Maxwell electrodynamics in the presence of both electric and magnetic sources, we formulate a local, manifestly duality-symmetric, Zwanziger-type action by introducing a pair of four-potentials A{sup ?} and B{sup ?} in a judicious way. On the two potentials A{sup ?} and B{sup ?} the SL(2,R) duality transformation acts in a simple linear manner. In quantum theory including charged source fields, this action can be recast as a SL(2,Z)-invariant action. Also given is a Zwanziger-type action for SL(2,R) duality-invariant Born–Infeld electrodynamics which can be important for D-brane dynamics in string theory. -- Highlights: •We formulate a local, manifestly duality-symmetric, Zwanziger-type action. •Maxwell electrodynamics is generalized to include dilaton and axion fields. •SL(2,R) symmetry is manifest. •We formulate a local, manifestly duality-symmetric, nonlinear Born–Infeld action with SL(2,R) symmetry.

Lee, Choonkyu, E-mail: cklee@phya.snu.ac.kr [Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747 (Korea, Republic of) [Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747 (Korea, Republic of); School of Physics, Korea Institute for Advanced Study, Seoul 130-722 (Korea, Republic of); Min, Hyunsoo, E-mail: hsmin@dirac.uos.ac.kr [Department of Physics, University of Seoul, Seoul 130-743 (Korea, Republic of)] [Department of Physics, University of Seoul, Seoul 130-743 (Korea, Republic of)

2013-12-15

416

PT-symmetric laser-absorber  

E-print Network

In a recent work, Y.D. Chong et al. [Phys. Rev. Lett. {\\bf 105}, 053901 (2010)] proposed the idea of a coherent perfect absorber (CPA) as the time-reversed counterpart of a laser, in which a purely incoming radiation pattern is completely absorbed by a lossy medium. The optical medium that realizes CPA is obtained by reversing the gain with absorption, and thus it generally differs from the lasing medium. Here it is shown that a laser with an optical medium that satisfies the parity-time $(\\mathcal{PT})$ symmetry condition $\\epsilon(-\\mathbf{r})=\\epsilon^*(\\mathbf{r})$ for the dielectric constant behaves simultaneously as a laser oscillator (i.e. it can emit outgoing coherent waves) and as a CPA (i.e. it can fully absorb incoming coherent waves with appropriate amplitudes and phases). Such a device can be thus referred to as a $\\mathcal{PT}$-symmetric CPA-laser. The general amplification/absorption features of the $\\mathcal{PT}$ CPA-laser below lasing threshold driven by two fields are determined.

Stefano Longhi

2010-08-31

417

Phase Behavior of Symmetric Sulfonated Block Copolymers  

SciTech Connect

Phase behavior of poly(styrenesulfonate-methylbutylene) (PSS-PMB) block copolymers was studied by varying molecular weight, sulfonation level, and temperature. Molecular weights of the copolymers range from 2.9 to 117 kg/mol. Ordered lamellar, gyroid, hexagonally perforated lamellae, and hexagonally packed cylinder phases were observed in spite of the fact that the copolymers are nearly symmetric with PSS volume fractions between 0.45 and 0.50. The wide variety of morphologies seen in our copolymers is inconsistent with current theories on block copolymer phase behavior such as self-consistent field theory. Low molecular weight PSS-PMB copolymers (<6.2 kg/mol) show order-order and order-disorder phase transitions as a function of temperature. In contrast, the phase behavior of high molecular weight PSS-PMB copolymers (>7.7 kg/mol) is independent of temperature. Due to the large value of Flory-Huggins interaction parameter, x, between the sulfonated and non-sulfonated blocks, PSS-PMB copolymers with PSS and PMB molecular weights of 1.8 and 1.4 kg/mol, respectively, show the presence of an ordered gyroid phase with a 2.5 nm diameter PSS network. A variety of methods are used to estimate x between PSS and PMB chains as a function of sulfonation level. Some aspects of the observed phase behavior of PSS-PMB copolymers can be rationalized using x.

Park, Moon Jeong; Balsara, Nitash P. (UCB)

2008-08-21

418

Surface gravity in dynamical spherically symmetric spacetimes  

E-print Network

A definition of surface gravity at the apparent horizon of dynamical spherically symmetric spacetimes is proposed. It is based on a unique foliation by ingoing null hypersurfaces. The function parametrizing the hypersurfaces can be interpreted as the phase of a light wave uniformly emitted by some far-away static observer. The definition gives back the accepted value of surface gravity in the static case by virtue of its nonlocal character. Although the definition is motivated by the behavior of outgoing null rays, it turns out that there is a simple connection between the generalized surface gravity, the acceleration of any radially moving observer, and the observed frequency change of the infalling light signal. In particular, this gives a practical and simple method of how any geodesic observer can determine surface gravity by measuring only the redshift of the infalling light wave. The surface gravity can be expressed as an integral of matter field quantities along an ingoing null line, which shows that it is a continuous function along the apparent horizon. A formula for the area change of the apparent horizon is presented, and the possibility of thermodynamical interpretation is discussed. Finally, concrete expressions of surface gravity are given for a number of four-dimensional and two-dimensional dynamical black hole solutions.

G. Fodor; K. Nakamura; Y. Oshiro; A. Tomimatsu

1996-03-22

419

Linear Thermodynamics of Rodlike DNA Filtration  

E-print Network

Linear thermodynamics transportation theory is employed to study filtration of rodlike DNA molecules. Using the repeated nanoarray consisting of alternate deep and shallow regions, it is demonstrated that the complex ...

Li, Zirui

420

Baroclinic tides in an axially symmetric basin  

E-print Network

INTRODUCTION AViD LITERATURE REVIEW . 1 Barotropic Tides . 2 Recognition and Observation of Baroclinic Tides 3 Baroclinic Tide Generation Mechanisms 4 t'Iodels of Baroclinic Tides . , 5 Overview of the Present Study . . RESEARCH METHODS 1 Linearized... Equations of Motion on an f-plane. . . . 2 Local Vertical Structure Functions . 3 Coupled Normal Mode Equations . 4 The Coupling Matrix . . 5 Transform of Modal Equations to the Frequency Domain . 6 Inner and Outer Boundary Conditions . 7 Solution...

Dever, Edward Paul

2012-06-07

421

International Workshop on Linear Colliders 2010  

ScienceCinema

IWLC2010 International Workshop on Linear Colliders 2010ECFA-CLIC-ILC joint meeting: Monday 18 October - Friday 22 October 2010Venue: CERN and CICG (International Conference Centre Geneva, Switzerland) This year, the International Workshop on Linear Colliders organized by the European Committee for Future Accelerators (ECFA) will study the physics, detectors and accelerator complex of a linear collider covering both CLIC and ILC options.Contact Workshop Secretariat  IWLC2010 is hosted by CERN

None

2011-10-06

422

Regularizing Linear Discriminant Analysis for Speech Recognition  

E-print Network

Regularizing Linear Discriminant Analysis for Speech Recognition Hakan Erdogan Faculty in a pattern recognition system is the feature extractor. Feature extraction is an important step for speech recognition since the time-domain speech signal is highly variable, thus complex linear and nonlinear

Erdogan, Hakan

423

Hydrogen-bonded complexes between dimethyl sulfoxide and monoprotic acids: molecular properties and IR spectroscopy.  

PubMed

MP2/6-31++G(d,p) and DFT B3LYP/6-31++G(d,p) calculations were performed of the structure, binding energies, and vibrational modes of complexes between dimethyl sulfoxide (DMSO) as a proton acceptor and monoprotic linear acids HX (X = F, Cl, CN) as well as monoprotic carboxylic acids HOOCR (R?=?-H, -CH3, -C6H5) in 1:1 and 1:2 stoichiometric ratios. The results show that two different structures are possible in the 1:2 ratio: in the first, the DMSO molecule interacts with both acid molecules (leading to a "Y" structure); in the second, the DMSO interacts with only one monoprotic acid. The second structure shows a lower stability per hydrogen bond. The spontaneities of the reactions to form the 1:1 and 1:2 complexes are greatly influenced by the X group of the linear acid. With the exception of HCN, all the reactions are spontaneous. In the 1:2 complexes with Y structure, we observed that the hydrogen atoms of the linear acid are coupled in symmetric and asymmetric modes, while this type of coupling is absent from the other 1:2 complexes. PMID:25342154

Belarmino, Márcia K D L; Cruz, Vanessa F; Lima, Nathália B D

2014-11-01

424

Design Concepts for Power Distribution Equipment Serving Non-Linear Loads  

E-print Network

, transformers, and power capacitors. SYMMETRICAL COMPONENT ANALYSIS The phase currents on a balanced, three-phase, four-wire, grounded-neutral distribution system, separated by 120? and equal in magnitude, add vectorially and cancel in the grounded... conductor overload, high neutral-to-ground voltage drop, and circulating current in the delta primary winding of delta-wye connected distribution transformers. Symmetrical Components and Non-Linear Loads A balanced load on a power distribution system...

Massey, G. W.

425

Role of skew-symmetric differential forms in mathematics  

E-print Network

Skew-symmetric forms possess unique capabilities. The properties of closed exterior and dual forms, namely, invariance, covariance, conjugacy and duality, either explicitly or implicitly appear in all invariant mathematical formalisms. This enables one to see an internal connection between various branches of mathematics. However, the theory of closed exterior forms cannot be completed without an answer to a question of how the closed exterior forms emerge. In the present paper we discus essentially new skew-symmetric forms, which generate closed exterior forms. Such skew-symmetric forms, which are evolutionary ones, are derived from differential equations, and, in contrast to exterior forms, they are defined on nonintegrable manifolds.

L. I. Petrova

2010-04-05

426

Highly-dispersive electromagnetic induced transparency in planar symmetric metamaterials.  

PubMed

We propose, design and experimentally demonstrate highly-dispersive electromagnetically induced transparency (EIT) in planar symmetric metamaterials actively switched and controlled by angles of incidence. Full-wave simulation and measurement results show EIT phenomena, trapped-mode excitations and the associated local field enhancement of two symmetric metamaterials consisting of symmetrically split rings (SSR) and a fishscale (FS) metamaterial pattern, respectively, strongly depend on angles of incidence. The FS metamaterial shows much broader spectral splitting than the SSR metamaterial due to the surface current distribution variation. PMID:23038311

Lu, Xiqun; Shi, Jinhui; Liu, Ran; Guan, Chunying

2012-07-30

427

Chirally symmetric but confined hadrons at finite density  

E-print Network

At a critical finite chemical potential and low temperature QCD undergoes the chiral restoration phase transition. The folklore tradition is that simultaneously hadrons are deconfined and there appears the quark matter. We demonstrate that it is possible to have confined but chirally symmetric hadrons at a finite chemical potential and hence beyond the chiral restoration point at a finite chemical potential and low temperature there could exist a chirally symmetric matter consisting of chirally symmetric but confined hadrons. If it does happen in QCD, then the QCD phase diagram should be reconsidered with obvious implications for heavy ion programs and astrophysics.

L. Ya. Glozman; R. F. Wagenbrunn

2008-02-03

428

SYMMETRIC LIVIDITY OF THE SOLES AS SEEN IN PRIVATE PRACTICE  

PubMed Central

As seen in private practice, symmetric lividity of the soles is a relatively common condition which occurs predominantly in males in the first three decades of life. Untreated, the syndrome may persist for many years or it may be self-limiting, lasting only a few days. Occupation does not seem to be a factor predisposing to symmetric lividity of the soles. There is a high incidence of family occurrence of this condition. Any form of treatment which controls the hyperhidrosis controls the other symptoms of symmetric lividity of the soles. PMID:13364666

Nelson, Lawrence M.

1956-01-01

429

Geometric characteristics of aberrations of plane-symmetric optical systems  

SciTech Connect

The geometric characteristics of aberrations of plane-symmetric optical systems are studied in detail with a wave-aberration theory. It is dealt with as an extension of the Seidel aberrations to realize a consistent aberration theory from axially symmetric to plane-symmetric systems. The aberration distribution is analyzed with the spot diagram of a ray and an aberration curve. Moreover, the root-mean-square value and the centroid of aberration distribution are discussed. The numerical results are obtained with the focusing optics of a toroidal mirror at grazing incidence.

Lu Lijun; Deng Zhiyong

2009-12-20

430

Signature for local Mixmaster dynamics in U(1) symmetric cosmologies  

E-print Network

Previous studies \\cite{berger98a} have provided strong support for a local, oscillatory approach to the singularity in U(1) symmetric, spatially inhomogeneous vacuum cosmologies on $T^3 \\times R$. The description of a vacuum Bianchi type IX, spatially homogeneous Mixmaster cosmology (on $S^3 \\times R$) in terms of the variables used to describe the U(1) symmetric cosmologies indicates that the oscillations in the latter are in fact those of local Mixmaster dynamics. One of the variables of the U(1) symmetric models increases only at the end of a Mixmaster era. Such an increase therefore yields a qualitative signature for local Mixmaster dynamics in spatially inhomogeneous cosmologies.

Beverly K. Berger; Vincent Moncrief

2000-06-20

431

Bayesian Nonparametric Inference of Switching Dynamic Linear Models  

E-print Network

Many complex dynamical phenomena can be effectively modeled by a system that switches among a set of conditionally linear dynamical modes. We consider two such models: the switching linear dynamical system (SLDS) and the ...

Fox, Emily

432

Enhanced Sensitivity of Anti-Symmetrically Structured Surface Plasmon Resonance Sensors with Zinc Oxide Intermediate Layers  

PubMed Central

We report a novel design wherein high-refractive-index zinc oxide (ZnO) intermediary layers are used in anti-symmetrically structured surface plasmon resonance (SPR) devices to enhance signal quality and improve the full width at half maximum (FWHM) of the SPR reflectivity curve. The surface plasmon (SP) modes of the ZnO intermediary layer were excited by irradiating both sides of the Au film, thus inducing a high electric field at the Au/ZnO interface. We demonstrated that an improvement in the ZnO (002) crystal orientation led to a decrease in the FWHM of the SPR reflectivity curves. We optimized the design of ZnO thin films using different parameters and performed analytical comparisons of the ZnO with conventional chromium (Cr) and indium tin oxide (ITO) intermediary layers. The present study is based on application of the Fresnel equation, which provides an explanation and verification for the observed narrow SPR reflectivity curve and optical transmittance spectra exhibited by (ZnO/Au), (Cr/Au), and (ITO/Au) devices. On exposure to ethanol, the anti-symmetrically structured showed a huge electric field at the Au/ZnO interface and a 2-fold decrease in the FWHM value and a 1.3-fold larger shift in angle interrogation and a 4.5-fold high-sensitivity shift in intensity interrogation. The anti-symmetrically structured of ZnO intermediate layers exhibited a wider linearity range and much higher sensitivity. It also exhibited a good linear relationship between the incident angle and ethanol concentration in the tested range. Thus, we demonstrated a novel and simple method for fabricating high-sensitivity, high-resolution SPR biosensors that provide high accuracy and precision over relevant ranges of analyte measurement. PMID:24361929

Tu, Yi-Chen; Huang, Teng-Yi; Chiu, Nan-Fu

2014-01-01

433

Enhanced sensitivity of anti-symmetrically structured surface plasmon resonance sensors with zinc oxide intermediate layers.  

PubMed

We report a novel design wherein high-refractive-index zinc oxide (ZnO) intermediary layers are used in anti-symmetrically structured surface plasmon resonance (SPR) devices to enhance signal quality and improve the full width at half maximum (FWHM) of the SPR reflectivity curve. The surface plasmon (SP) modes of the ZnO intermediary layer were excited by irradiating both sides of the Au film, thus inducing a high electric field at the Au/ZnO interface. We demonstrated that an improvement in the ZnO (002) crystal orientation led to a decrease in the FWHM of the SPR reflectivity curves. We optimized the design of ZnO thin films using different parameters and performed analytical comparisons of the ZnO with conventional chromium (Cr) and indium tin oxide (ITO) intermediary layers. The present study is based on application of the Fresnel equation, which provides an explanation and verification for the observed narrow SPR reflectivity curve and optical transmittance spectra exhibited by (ZnO/Au), (Cr/Au), and (ITO/Au) devices. On exposure to ethanol, the anti-symmetrically structured showed a huge electric field at the Au/ZnO interface and a 2-fold decrease in the FWHM value and a 1.3-fold larger shift in angle interrogation and a 4.5-fold high-sensitivity shift in intensity interrogation. The anti-symmetrically structured of ZnO intermediate layers exhibited a wider linearity range and much higher sensitivity. It also exhibited a good linear relationship between the incident angle and ethanol concentration in the tested range. Thus, we demonstrated a novel and simple method for fabricating high-sensitivity, high-resolution SPR biosensors that provide high accuracy and precision over relevant ranges of analyte measurement. PMID:24361929

Chiu, Nan-Fu; Tu, Yi-Chen; Huang, Teng-Yi

2013-01-01

434

Implementation of a symmetric boundary integral formulation for cohesive cracks in homogeneous media and at interfaces  

SciTech Connect

A symmetric boundary integral formulation for cohesive cracks growing in the interior of homogeneous linear elastic isotropic media and/or at interfaces between these media is developed and implemented in a numerical code. The solution of a problem that includes cohesive cracks depends on the cohesive law adopted. In the present work, models based on the concept of free energy density per unit undeformed area are considered. The corresponding constitutive cohesive equations present a softening branch which induces to the problem a potential instability. Thus, the development and implementation of a suitable solution algorithm capable of following the growth of the cohesive zone becomes an important issue. An arc-length control combined with a Newton-Raphson algorithm for iterative solution of nonlinear equations is used. The Boundary Element Method is very attractive for modeling cohesive crack problems as all nonlinearities are located on the boundaries (including the crack boundaries) of linear elastic domains. A Galerkin approximation scheme, applied to a suitable symmetric integral formulation, ensures an easy treatment of cracks in homogeneous media and excellent convergence behavior of the numerical solution. Numerical results for the wedge split test are presented and compared with experimental results available in the literature.

Tavara, Luis [University of Seville; Mantic, Vladislav [University of Seville; Salvadori, Alberto [ORNL; Gray, Leonard J [ORNL; Paris, Federico [University of Seville

2009-01-01

435

A Possible Method for Non-Hermitian and Non-PT-Symmetric Hamiltonian Systems  

PubMed Central

A possible method to investigate non-Hermitian Hamiltonians is suggested through finding a Hermitian operator ?+ and defining the annihilation and creation operators to be ?+ -pseudo-Hermitian adjoint to each other. The operator ?+ represents the ?+ -pseudo-Hermiticity of Hamiltonians. As an example, a non-Hermitian and non-PT-symmetric Hamiltonian with imaginary linear coordinate and linear momentum terms is constructed and analyzed in detail. The operator ?+ is found, based on which, a real spectrum and a positive-definite inner product, together with the probability explanation of wave functions, the orthogonality of eigenstates, and the unitarity of time evolution, are obtained for the non-Hermitian and non-PT-symmetric Hamiltonian. Moreover, this Hamiltonian turns out to be coupled when it is extended to the canonical noncommutative space with noncommutative spatial coordinate operators and noncommutative momentum operators as well. Our method is applicable to the coupled Hamiltonian. Then the first and second order noncommutative corrections of energy levels are calculated, and in particular the reality of energy spectra, the positive-definiteness of inner products, and the related properties (the probability explanation of wave functions, the orthogonality of eigenstates, and the unitarity of time evolution) are found not to be altered by the noncommutativity. PMID:24896084

Li, Jun-Qing; Miao, Yan-Gang; Xue, Zhao

2014-01-01

436

A parallel algorithm for the non-symmetric eigenvalue problem  

SciTech Connect

This paper describes a parallel algorithm for computing the eigenvalues and eigenvectors of a non-symmetric matrix. The algorithm is based on a divide-and-conquer procedure and uses an iterative refinement technique.

Dongarra, J.; Sidani, M. (Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science Oak Ridge National Lab., TN (United States))

1991-12-01

437

Twistor spinors on Lorentzian symmetric spaces Helga Baum  

E-print Network

.Penrose in General Relativity (see [Pen67], [PR86 * *], [NW84 ]). They are related to Killing vector fields in semi Twistor spinors on Lorentzian symmetric spaces spinors has constant sectional curvature. Furthermore, each homog* *eneous Riemannian manifold

Baum, Helga

438

Symmetric Pin Diversion Detection using a Partial Defect Detector (PDET)  

SciTech Connect

Since the signature from the Partial Defect Detector (PDET) is principally dependent on the geometric layout of the guide tube locations, the capability of the technique in detecting symmetric diversion of pins needs to be determined. The Monte Carlo simulation study consisted of cases where pins were removed in a symmetric manner and the resulting signatures were examined. In addition to the normalized gamma-to-neutron ratios, the neutron and gamma signatures normalized to their maximum values, were also examined. Examination of the shape of the three curves as well as of the peak-to-valley differences in excess of the maximum expected in intact assemblies, indicated pin diversion. A set of simulations with various symmetric patterns of diversion were examined. The results from these studies indicated that symmetric diversions as low as twelve percent could be detected by this methodology.

Sitaraman, S; Ham, Y S

2009-06-01

439

Toward an Efficient Column Minimum Degree Code for Symmetric Multiprocessors  

E-print Network

Toward an Efficient Column Minimum Degree Code for Symmetric Multiprocessors Tzu­Yi Chen \\Lambda machines, as well as on a Sun Enterprise 5000). We present our conclusions in Section 6. 2 Background

Chen, Tzu-Yi

440

Local unitary group stabilizers and entanglement for multiqubit symmetric states  

E-print Network

We refine recent local unitary entanglement classification for symmetric pure states of $n$ qubits (that is, states invariant under permutations of qubits) using local unitary stabilizer subgroups and Majorana configurations. Stabilizer subgroups carry more entanglement distinguishing power than do the stabilizer subalgebras used in our previous work. We extend to mixed states recent results about local operations on pure symmetric states by showing that if two symmetric density operators are equivalent by a local unitary operation, then they are equivalent via a local unitary operation that is the {\\em same} in each qubit. A geometric consequence, used in our entanglement classification, is that two symmetric pure states are local unitary equivalent if and only if their Majorana configurations can be interchanged by a rotation of the Bloch sphere.

Curt D. Cenci; David W. Lyons; Scott N. Walck

2010-11-23

441

Microgrid Fault Protection Based on Symmetrical and Differential Current Components  

E-print Network

Microgrid Fault Protection Based on Symmetrical and Differential Current Components Prepared.1. SINGLE LINE-TO-GROUND (SLG) FAULTS................................................12 3.2. LINE-TO-LINE (L-TO-L) FAULTS ..............................................................14 4. PROTECTION BASED

442

Scheduling Multiple Multithreaded Applications on Asymmetric and Symmetric Chip Multiprocessors  

E-print Network

Scheduling Multiple Multithreaded Applications on Asymmetric and Symmetric Chip Multiprocessors to improve performance, fairness and jitter of workloads consisting of multiple multithreaded applications and jitter in execution runtimes when dealing with multiple multithreaded applications running in parallel

Kolodny, Avinoam

443

Scheduling Multiple Multithreaded Applications on Asymmetric and Symmetric Chip Multiprocessors  

E-print Network

Scheduling Multiple Multithreaded Applications on Asymmetric and Symmetric Chip Multiprocessors techniques to improve performance, fairness and jitter of workloads consisting of multiple multithreaded between applications and jitter in execution runtimes when dealing with multiple multithreaded

Kolodny, Avinoam

444

Application of linear logic to simulation  

NASA Astrophysics Data System (ADS)

Linear logic, since its introduction by Girard in 1987 has proven expressive and powerful. Linear logic has provided natural encodings of Turing machines, Petri nets and other computational models. Linear logic is also capable of naturally modeling resource dependent aspects of reasoning. The distinguishing characteristic of linear logic is that it accounts for resources; two instances of the same variable are considered differently from a single instance. Linear logic thus must obey a form of the linear superposition principle. A proportion can be reasoned with only once, unless a special operator is applied. Informally, linear logic distinguishes two kinds of conjunction, two kinds of disjunction, and also introduces a modal storage operator that explicitly indicates propositions that can be reused. This paper discuses the application of linear logic to simulation. A wide variety of logics have been developed; in addition to classical logic, there are fuzzy logics, affine logics, quantum logics, etc. All of these have found application in simulations of one sort or another. The special characteristics of linear logic and its benefits for simulation will be discussed. Of particular interest is a connection that can be made between linear logic and simulated dynamics by using the concept of Lie algebras and Lie groups. Lie groups provide the connection between the exponential modal storage operators of linear logic and the eigen functions of dynamic differential operators. Particularly suggestive are possible relations between complexity result for linear logic and non-computability results for dynamical systems.

Clarke, Thomas L.

1998-08-01

445

A linear quadratic regulator approach to the stabilization of uncertain linear systems  

NASA Technical Reports Server (NTRS)

This paper presents a linear quadratic regulator approach to the stabilization of uncertain linear systems. The uncertain systems under consideration are described by state equations with the presence of time-varying unknown-but-bounded uncertainty matrices. The method is based on linear quadratic regulator (LQR) theory and Liapunov stability theory. The robust stabilizing control law for a given uncertain system can be easily constructed from the symmetric positive-definite solution of the associated augmented Riccati equation. The proposed approach can be applied to matched and/or mismatched systems with uncertainty matrices in which only their matrix norms are bounded by some prescribed values and/or their entries are bounded by some prescribed constraint sets. Several numerical examples are presented to illustrate the results.

Shieh, L. S.; Sunkel, J. W.; Wang, Y. J.

1990-01-01

446

Crossing symmetric potential model of pion-nucleon scattering  

SciTech Connect

A crossing symmetric {pi}N scattering amplitude is constructed through a complete attachment of two external pions to the dressed nucleon propagator of an underlying {pi}N potential model. Our formulation automatically provides expressions also for the crossing symmetric and gauge invariant pion photoproduction and Compton scattering amplitudes. We show that our amplitudes are unitary if they coincide on-shell with the amplitudes obtained by attaching one pion to the dressed {pi}NN vertex of the same potential model.

Blankleider, B.; Skawronski, T. [School of Chemical and Physical Sciences, Flinders University, South Australia (Australia); Kvinikhidze, A. N. [Razmadze Mathematical Institute (Georgia)

2010-07-27

447

A wave refraction analysis for an axially symmetrical island  

E-print Network

A WAVE REFRACTION ANALYSIS FOR AN AXIALLY SYMMETRICAL ISLAND A Thesis By LIEUTENANT RONALD J FORST UNITED STATES NAVY Submitted to the Graduate College of the Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE l966 Major Subject Oceanography A WAVE REFRACTION ANALYSIS FOR AN AXIALLY SYMMETRICAL ISLAND A Thesis By LIEUTENANT RONALD J FORST UNITED STATES NAVY Approved as to style and content by; ( airma Committee) Head of Dep rtme t...

Forst, Ronald John

2012-06-07

448

On the Averaging of Symmetric Positive-Definite Tensors  

Microsoft Academic Search

In this paper we present properly invariant averaging procedures for symmetric positive-definite tensors which are based on different measures of nearness of symmetric positive-definite tensors. These procedures intrinsically account for the positive-definite property of the tensors to be averaged. They are independent of the coordinate system, preserve material symmetries, and more importantly, they are invariant under inversion. The results of

Maher Moakher

2006-01-01

449

Frequency estimation by linear prediction  

Microsoft Academic Search

The application of linear prediction to frequency estimation for sinusoidal signals in noise is investigated. It is shown that improved performance is obtained by processing a complex-valued version of the real-valued input signal, with the corresponsing sampling rate reduced by one-half. The case of a single sinusoid in white noise is studied in detail, including the eigenvalues of the covariance

Leland B. Jackson; Donald W. Tufts; Frank K. Soong; Rahul M. Rao

1978-01-01

450

Regular Descriptor Linear Systems  

Microsoft Academic Search

\\u000a We have pointed out in Sect. 1.3 that regularity is a very important property for descriptor linear systems. It guarantees\\u000a the existence and uniqueness of solutions to descriptor linear systems. This chapter studies regular descriptor linear systems\\u000a and starts in Sect. 3.1 with the definition of regularity of descriptor linear systems and its relation with solutions of\\u000a descriptor linear systems.

Guang-Ren Duan

451

Linear Dependencies in Weyl-Heisenberg Orbits  

E-print Network

Five years ago, Lane Hughston showed that some of the symmetric informationally complete positive operator valued measures (SICs) in dimension 3 coincide with the Hesse configuration (a structure well known to algebraic geometers, which arises from the torsion points of a certain elliptic curve). This connection with elliptic curves is signalled by the presence of linear dependencies among the SIC vectors. Here we look for analogous connections between SICs and algebraic geometry by performing computer searches for linear dependencies in higher dimensional SICs. We prove that linear dependencies will always emerge in Weyl-Heisenberg orbits when the fiducial vector lies in a certain subspace of an order 3 unitary matrix. This includes SICs when the dimension is divisible by 3 or equal to 8 mod 9. We examine the linear dependencies in dimension 6 in detail and show that smaller dimensional SICs are contained within this structure, potentially impacting the SIC existence problem. We extend our results to look for linear dependencies in orbits when the fiducial vector lies in an eigenspace of other elements of the Clifford group that are not order 3. Finally, we align our work with recent studies on representations of the Clifford group.

Hoan Bui Dang; Kate Blanchfield; Ingemar Bengtsson; D. M. Appleby

2012-11-01

452

Robustness of differentiation cascades with symmetric stem cell division.  

PubMed

Stem cells (SCs) perform the task of maintaining tissue homeostasis by both self-renewal and differentiation. While it has been argued that SCs divide asymmetrically, there is also evidence that SCs undergo symmetric division. Symmetric SC division has been speculated to be key for expanding cell numbers in development and regeneration after injury. However, it might lead to uncontrolled growth and malignancies such as cancer. In order to explore the role of symmetric SC division, we propose a mathematical model of the effect of symmetric SC division on the robustness of a population regulated by a serial differentiation cascade and we show that this may lead to extinction of such population. We examine how the extinction likelihood depends on defining characteristics of the population such as the number of intermediate cell compartments. We show that longer differentiation cascades are more prone to extinction than systems with less intermediate compartments. Furthermore, we have analysed the possibility of mixed symmetric and asymmetric cell division against invasions by mutant invaders in order to find optimal architecture. Our results show that more robust populations are those with unfrequent symmetric behaviour. PMID:24718457

Sánchez-Taltavull, Daniel; Alarcón, Tomás

2014-06-01

453

Space Complexity Algorithms & Complexity  

E-print Network

Space Complexity Algorithms & Complexity Space Complexity Nicolas Stroppa Patrik Lambert - plambert@computing.dcu.ie CA313@Dublin City University. 2008-2009. December 4, 2008 #12;Space Complexity Hierarchy of problems #12;Space Complexity NP-intermediate Languages If P = NP, then are there languages which neither in P

Way, Andy

454

Mode competition of rotating waves in reflection-symmetric Taylor-Couette flow  

NASA Astrophysics Data System (ADS)

We report on the results of a combined experimental and numerical study on mode interactions of rotating waves in Taylor Couette flow. Our work shows that rotating waves which originate at a Hopf bifurcation from the steady axisymmetric Taylor vortex flow interact with this axisymmetric flow in a codimension-two fold-Hopf bifurcation. This interaction gives rise to an (unstable) low-frequency modulated wave via a subcritical Neimark Sacker bifurcation from the rotating wave. At higher Reynolds numbers, a complicated mode interation between stable modulated waves originating at a different Neimark Sacker bifurcation and a pair of symmetrically related rotating waves that originate at a cyclic pitchfork bifurcation is found to organize complex Z_2-symmetry breaking of rotating waves via global bifurcations. In addition to symmetry breaking of rotating waves via a (local) cyclic pitchfork bifurcation, we found symmetry breaking of modulated waves via a saddle-node-infinite-period (SNIP) global bifurcation. Tracing these local and global bifurcation curves in Reynolds number/aspect ratio parameter space toward their apparant merging point, unexpected complexity arises in the bifurcation structure involving non-symmetric two-tori undergoing saddle-loop homoclinic bifurcations. The close agreement between the numerics and the experiment is indicative of the robustness of the observed complex dynamics.

Abshagen, J.; Lopez, J. M.; Marques, F.; Pfister, G.

2005-09-01

455

Absence of topological insulator phases in non-Hermitian PT-symmetric Hamiltonians  

SciTech Connect

In this work, we consider a generalization of the symmetry classification of topological insulators to non-Hermitian Hamiltonians, which satisfy a combined PT symmetry (parity and time reversal). We show via examples and explicit proofs from separate bulk and gapless boundary-state perspectives that the typical paradigm of forming topological insulator states from Dirac Hamiltonians is not compatible with the construction of non-Hermitian PT-symmetric Hamiltonians. The topological insulator states are PT-breaking phases and have energy spectra that are complex (not real) and, thus, are not consistent quantum theories.

Hu Yichen; Hughes, Taylor L. [Department of Physics, University of Illinois, 1110 West Green St., Urbana, Illinois 61801 (United States)

2011-10-15

456

Families of particles with different masses in PT-symmetric quantum field theory  

E-print Network

An elementary field-theoretic mechanism is proposed that allows one Lagrangian to describe a family of particles having different masses but otherwise similar physical properties. The mechanism relies on the observation that the Dyson-Schwinger equations derived from a Lagrangian can have many different but equally valid solutions. Nonunique solutions to the Dyson-Schwinger equations arise when the functional integral for the Green's functions of the quantum field theory converges in different pairs of Stokes' wedges in complex field space, and the solutions are physically viable if the pairs of Stokes' wedges are PT symmetric.

C. M. Bender; S. P. Klevansky

2010-02-17

457

Families of Particles with Different Masses in PT-Symmetric Quantum Field Theory  

SciTech Connect

An elementary field-theoretic mechanism is proposed that allows one Lagrangian to describe a family of particles having different masses but otherwise similar physical properties. The mechanism relies on the observation that the Dyson-Schwinger equations derived from a Lagrangian can have many different but equally valid solutions. Nonunique solutions to the Dyson-Schwinger equations arise when the functional integral for the Green's functions of the quantum field theory converges in different pairs of Stokes' wedges in complex-field space, and the solutions are physically viable if the pairs of Stokes' wedges are PT symmetric.

Bender, Carl M. [Physics Department, Washington University, St. Louis, Missouri 63130 (United States); Klevansky, S. P. [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 19, 69120 Heidelberg (Germany)

2010-07-16

458

Complex Systems  

PubMed Central

Physiologic systems in health and disease display an extraordinary range of temporal behaviors and structural patterns that defy understanding based on linear constructs, reductionist strategies, and classical homeostasis. Application of concepts and computational tools derived from the contemporary study of complex systems, including nonlinear dynamics, fractals and “chaos theory,” is having an increasing impact on biology and medicine. This presentation provides a brief overview of an emerging area of biomedical research, including recent applications to cardiopulmonary medicine and chronic obstructive lung disease. PMID:16921107

Goldberger, Ary L.

2006-01-01

459

How (non-) linear is the hydrodynamics of heavy ion collisions?  

E-print Network

We provide evidence from full numerical solutions that the hydrodynamical evolution of initial density fluctuations in heavy ion collisions can be understood order-by-order in a perturbative series in deviations from a smooth and azimuthally symmetric background solution. To leading linear order, modes with different azimuthal wave numbers do not mix. Quadratic and higher order corrections are small and can be understood as overtones with corresponding wave numbers.

Stefan Floerchinger; Urs Achim Wiedemann; Andrea Beraudo; Luca Del Zanna; Gabriele Inghirami; Valentina Rolando

2013-12-19

460

Filter bank algorithms for piecewise linear prewavelets on arbitrary triangulations  

NASA Astrophysics Data System (ADS)

This paper studies algorithms for decomposition, reconstruction, and approximation based on piecewise linear prewavelets on bounded triangulations of arbitrary topology. Our key mathematical result is showing that the Schur complement of the associated two scale matrix is symmetric, positive definite, and well conditioned. Numerical examples suggest that thresholding based on prewavelets yields a smaller approximation error than when based on the simple [`]Faber' decomposition scheme.

Floater, Michael S.; Quak, Ewald G.; Reimers, Martin

2000-07-01

461

A multi-level method for sparse linear systems  

SciTech Connect

A multi-level method for the solution of sparse linear systems is introduced. The definition of the method is based on data from the coefficient matrix alone. An upper bound for the condition number is available for certain symmetric positive definite (SPD) problems. Numerical experiments confirm the analysis and illustrate the efficiency of the method for diffusion problems with discontinuous coefficients with discontinuities which are not aligned with the coarse meshes.

Shapira, Y.

1997-09-01

462

Cohesive-zone-model formulation and implementation using the symmetric Galerkin boundary element method for homogeneous solids  

NASA Astrophysics Data System (ADS)

A new symmetric boundary integral formulation for cohesive cracks growing in the interior of homogeneous linear elastic isotropic media with a known crack path is developed and implemented in a numerical code. A crack path can be known due to some symmetry implications or the presence of a weak or bonded surface between two solids. The use of a two-dimensional exponential cohesive law and of a special technique for its inclusion in the symmetric Galerkin boundary element method allows us to develop a simple and efficient formulation and implementation of a cohesive zone model. This formulation is dependent on only one variable in the cohesive zone (relative displacement). The corresponding constitutive cohesive equations present a softening branch which induces to the problem a potential instability. The development and implementation of a suitable solution algorithm capable of following the growth of the cohesive zone and subsequent crack growth becomes an important issue. An arc-length control combined with a Newton-Raphson algorithm for iterative solution of nonlinear equations is developed. The boundary element method is very attractive for modeling cohesive crack problems as all nonlinearities are located along the boundaries (including the crack boundaries) of linear elastic domains. A Galerkin approximation scheme, applied to a suitable symmetric integral formulation, ensures an easy treatment of cracks in homogeneous media and excellent convergence behavior of the numerical solution. Numerical results for the wedge split and mixed-mode flexure tests are presented.

Távara, Luis; Manti?, Vladislav; Salvadori, Alberto; Gray, Leonard J.; París, Federico

2013-04-01

463

Linear Accelerator (LINAC)  

MedlinePLUS

... position doesn't vary from the original plan. Safety of the staff operating the linear accelerator is also important. The linear accelerator sits in a room with lead and concrete walls so that the ...

464

Positive Linear Function Machine  

NSDL National Science Digital Library

Students investigate linear functions with positive slopes by trying to guess the slope and intercept from inputs and outputs. Positive Linear Function Machine is one of the Interactivate assessment explorers.

465

Linear-algebraic ?-calculus  

Microsoft Academic Search

With a view towards models of quantum computation and\\/or the inter- pretation of linear logic, we define a functional language wh ere all functions are linear operators by construction. A small step operatio nal semantic (and hence an interpreter\\/simulator) is provided for this langu age in the form of a term rewrite system. The linear-algebraic ?-calculus hereby constructed is linear

Pablo ArrighiGilles Dowek

466

Approximate Noether Symmetries from Lagrangian for Plane Symmetric Spacetimes  

E-print Network

Noether symmetries from geodetic Lagrangian for time-conformal plane symmetric spacetime are presented. Here, time conformal factor is used to find the approximate Noether symmetries. This is a generalization of the idea discussed by I. Hussain and A. Noether symmetries from geodetic Lagrangian for time-conformal plane symmetric spacetime are presented. Here, time conformal factor is used to find the approximate Noether symmetries. This is a generalization of the idea discussed by I. Hussain and A. Qadir [3,4], where they obtained approximate Noether symmetries from Lagrangian for a particular plane symmetric static spacetime. In the present article, the most general plane symmetric static spacetime is considered and perturb it by introducing a general time conformal factor $e^{\\epsilon f(t)}$, where $\\epsilon$ is very small which causes the perturbation in the spacetime. Taking the perturbation up to the first order, we find all Lagrangian for plane symmetric spactimes from which approximate Noether symmetries exist. PACS 11.30.-j-Symmetries and conservation laws PACS 04.20.-q-Classical general Relativity

Farhad Ali; Tooba Feroze

2014-11-07

467

Linear-Algebra Programs  

NASA Technical Reports Server (NTRS)

The Basic Linear Algebra Subprograms (BLAS) library is a collection of 38 FORTRAN-callable routines for performing basic operations of numerical linear algebra. BLAS library is portable and efficient source of basic operations for designers of programs involving linear algebriac computations. BLAS library is supplied in portable FORTRAN and Assembler code versions for IBM 370, UNIVAC 1100 and CDC 6000 series computers.

Lawson, C. L.; Krogh, F. T.; Gold, S. S.; Kincaid, D. R.; Sullivan, J.; Williams, E.; Hanson, R. J.; Haskell, K.; Dongarra, J.; Moler, C. B.

1982-01-01