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1

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

2

Conjugate gradient type methods for linear systems with complex symmetric coefficient matrices  

NASA Technical Reports Server (NTRS)

We consider conjugate gradient type methods for the solution of large sparse linear system Ax equals b with complex symmetric coefficient matrices A equals A(T). Such linear systems arise in important applications, such as the numerical solution of the complex Helmholtz equation. Furthermore, most complex non-Hermitian linear systems which occur in practice are actually complex symmetric. We investigate conjugate gradient type iterations which are based on a variant of the nonsymmetric Lanczos algorithm for complex symmetric matrices. We propose a new approach with iterates defined by a quasi-minimal residual property. The resulting algorithm presents several advantages over the standard biconjugate gradient method. We also include some remarks on the obvious approach to general complex linear systems by solving equivalent real linear systems for the real and imaginary parts of x. Finally, numerical experiments for linear systems arising from the complex Helmholtz equation are reported.

Freund, Roland

1989-01-01

3

Complex symmetric matrices with strongly stable iterates  

NASA Technical Reports Server (NTRS)

Complex-valued symmetric matrices are studied. A simple expression for the spectral norm of such matrices is obtained, by utilizing a unitarily congruent invariant form. A sharp criterion is provided for identifying those symmetric matrices whose spectral norm is not exceeding one: such strongly stable matrices are usually sought in connection with convergent difference approximations to partial differential equations. As an example, the derived criterion is applied to conclude the strong stability of a Lax-Wendroff scheme.

Tadmor, E.

1985-01-01

4

Symmetric nested complexes of fullerenes.  

PubMed

Large fullerenes such as C180 and C116 can be used as hosts for other molecules of the same family. Based on this idea, two complexes were designed, one in which C180 accepts a C60 molecule as a guest and the other in which C20 was placed inside C116. The behavior of these new assemblies was closer to that of a large endohedral complex rather than onion-like. There were marked differences between the systems. In the first system, there was minor interaction between the two cages but the association resulted in a more stable thermodynamic state. In the second system, there was strong electronic interchange between the cages, and the thermodynamic results suggest that such a combination might be useful for forming stable C20. PMID:25823391

Mar, Naveicy; Sansores, Luis Enrique; Muhl, Stephen; Ramos, Estrella; Salcedo, Roberto

2015-04-01

5

Experimental scheme for unambiguous discrimination of linearly independent symmetric states  

SciTech Connect

We propose an experimental setup for discriminating four linearly independent nonorthogonal symmetric quantum states. The setup is based on linear optics only and can be configured to implement both optimal unambiguous state discrimination [Chefles and Barnett, Phys. Lett. A 250, 223 (1998)] and minimum error discrimination. In both cases, the setup is characterized by an optimal success probability. The experimental setup can be generalized to the case of discrimination among N linearly nonorthogonal symmetric quantum states. We also study the discrimination between two incoherent superpositions of symmetric states. In this case, the setup also achieves an optimal success probability in the case of unambiguous discrimination as well as minimum error discrimination.

Jimenez, O.; Burgos-Inostroza, E.; Delgado, A.; Saavedra, C. [Center for Quantum Optics and Quantum Information, Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Sanchez-Lozano, X. [Center for Quantum Optics and Quantum Information, Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Instituto de Fisica, Universidad de Guanajuato, P. O. Box E-143, 37150, Leon Guanajuato (Mexico)

2007-12-15

6

COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES AND MATSUKI DUALITY  

E-print Network

COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES AND MATSUKI favorite subjects of last 10-* *15 years - complex crowns of Riemannian symmetric spaces. In the last year is that there is a canonical G-invariant Stein neighborhood of X - complex crown Crown (X)-which must universally appear

7

COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES AND MATSUKI DUALITY  

E-print Network

COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES AND MATSUKI DUALITY Simon Gindikin Soji Kaneyuki­15 years ­ complex crowns of Riemannian symmetric spaces. In the last year there was a substantial progress ­ complex crown Crown(X)­which must universally appear in geometric and analytic problems on X [G

8

SOME REMARKS ON COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES  

E-print Network

SOME REMARKS ON COMPLEX CROWNS OF RIEMANN SYMMETRIC not start from a formal definition of crowns of Riemann symmetric spaces. There is only a confidence that for each such space X there is a canonical Stein neighborhood Crown (X), on which it can be extended to all

9

SOME REMARKS ON COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES  

E-print Network

SOME REMARKS ON COMPLEX CROWNS OF RIEMANN SYMMETRIC SPACES Simon Gindikin Abstract. We discuss definition of crowns of Riemann symmetric spaces. There is only a confidence that for each such space X there is a canonical Stein neighborhood Crown(X), on which it can be extended to all natural geometrical constructions

10

Irreducible complexity of iterated symmetric bimodal maps  

Microsoft Academic Search

We introduce a tree structure for the iterates of symmetric bimodal maps and identify a subset which we prove to be isomorphic to the family of unimodal maps. This subset is used as a second factor for a $\\\\ast $-product that we define in the space of bimodal kneading sequences. Finally, we give some properties for this product and study

J. P. Lampreia; R. Severino; J. Sousa Ramos

2004-01-01

11

Trigonometry of 'complex Hermitian'-type homogeneous symmetric spaces  

Microsoft Academic Search

This paper contains a thorough study of the trigonometry of the homogeneous symmetric spaces in the Cayley-Klein-Dickson family of spaces of 'complex Hermitian' type and rank-one. The complex Hermitian elliptic CP^N and hyperbolic CH^N spaces, their analogues with indefinite Hermitian metric and some non-compact symmetric spaces associated to SL(N+1,R) are the generic members in this family. The method encapsulates trigonometry

Ramón Ortega; Mariano Santander

2002-01-01

12

Irreducible complexity of iterated symmetric bimodal maps  

Microsoft Academic Search

We introduce a tree structure for the iterates of symmetric bimodal maps and\\u000aidentify a subset which we prove to be isomorphic to the family of unimodal\\u000amaps. This subset is used as a second factor for a $\\\\ast $-product that we\\u000adefine in the space of bimodal kneading sequences. Finally, we give some\\u000aproperties for this product and study

J. P. Lampreia; R. Severino; J. Sousa Ramos

2004-01-01

13

Irreducible complexity of iterated symmetric bimodal maps  

E-print Network

We introduce a tree structure for the iterates of symmetric bimodal maps and identify a subset which we prove to be isomorphic to the family of unimodal maps. This subset is used as a second factor for a $\\ast $-product that we define in the space of bimodal kneading sequences. Finally, we give some properties for this product and study the *-product induced on the associated Markov shifts.

J. P. Lampreia; R. Severino; J. Sousa Ramos

2004-03-08

14

Norm estimates of complex symmetric operators applied to quantum systems  

E-print Network

This paper communicates recent results in theory of complex symmetric operators and shows, through two non-trivial examples, their potential usefulness in the study of Schr\\"odinger operators. In particular, we propose a formula for computing the norm of a compact complex symmetric operator. This observation is applied to two concrete problems related to quantum mechanical systems. First, we give sharp estimates on the exponential decay of the resolvent and the single-particle density matrix for Schr\\"odinger operators with spectral gaps. Second, we provide new ways of evaluating the resolvent norm for Schr\\"odinger operators appearing in the complex scaling theory of resonances.

Emil Prodan; Stephan R. Garcia; Mihai Putinar

2005-10-24

15

Regularized symmetric indefinite systems in interior point methods for linear and quadratic optimization  

Microsoft Academic Search

This paper presents linear algebra techniques used in the implementation of an interior point method for solving linear programs and convex quadratic programs with linear constraints. New regularization techniques for Newton systems applicable to both symmetric positive definite and symmetric indefinite systems are described. They transform the latter to quasidef-inite systems known to be strongly factorizable to a form of

Anna Altman; Jacek Gondzio

1999-01-01

16

AN ITERATIVE METHOD FOR SOLVING COMPLEX-SYMMETRIC SYSTEMS ARISING IN ELECTRICAL POWER MODELING  

Microsoft Academic Search

We propose an iterative method for solving a complex-symmetric linear system arising in electric power networks. Our method extends Gremban, Miller, and Zagha's (in Proceedings of the International Parallel Processing Symposium, IEEE Computer Society, Los Alamitos, CA, 1995) support-tree preconditioner to handle complex weights and vastly different admittances. Our underlying iteration is a modification to transpose-free QMR (6) to enhance

VICTORIA E. HOWLE; STEPHEN A. VAVASIS

2000-01-01

17

Trigonometry of 'complex Hermitian' type homogeneous symmetric spaces  

E-print Network

This paper contains a thorough study of the trigonometry of the homogeneous symmetric spaces in the Cayley-Klein-Dickson family of spaces of 'complex Hermitian' type and rank-one. The complex Hermitian elliptic CP^N and hyperbolic CH^N spaces, their analogues with indefinite Hermitian metric and some non-compact symmetric spaces associated to SL(N+1,R) are the generic members in this family. The method encapsulates trigonometry for this whole family of spaces into a single "basic trigonometric group equation", and has 'universality' and '(self)-duality' as its distinctive traits. All previously known results on the trigonometry of CP^N and CH^N follow as particular cases of our general equations. The physical Quantum Space of States of any quantum system belongs, as the complex Hermitian space member, to this parametrised family; hence its trigonometry appears as a rather particular case of the equations we obtain.

Ramon Ortega; Mariano Santander

2001-12-14

18

A CAD\\/CAPP interface for complex rotationally symmetric parts  

Microsoft Academic Search

A new methodology for interfacing Computer-Aided Design (CAD) and Computer-Aided Process Planning (CAPP) based on automatic feature recognition is proposed in the domain of complex rotationally symmetric parts. The interface system consists of three stages: (1) Initial Graphics Exchange Specification (1GES) data translation, (2) polygonal decomposition or splitting, (3) automatic recognition of precedences and features. In the data translation stage,

M. Y. JUNG; K. H. LEE

1996-01-01

19

A low-power high-linearity symmetrical readout circuit for capacitive sensors  

Microsoft Academic Search

This paper presents a symmetrical readout circuit for capacitive sensors. Based on charge transfer principle, it is insensitive to stray capacitors. Introducing a reference branch, this symmetrical readout circuit can enlarge its linear range, reduce amplifier offsets and reject common-mode noise and even-order distortions. Chopper stabilization technique is used to reduce the negative effects of the amplifier offset and flicker

Kaimin Zhou; Ziqiang Wang; Fule Li; Chun Zhang; Zhihua Wang

2011-01-01

20

Generalized Householder transformations for the complex symmetric eigenvalue problem  

NASA Astrophysics Data System (ADS)

We present an intuitive and scalable algorithm for the diagonalization of complex symmetric matrices, which arise from the projection of pseudo-Hermitian and complex scaled Hamiltonians onto a suitable basis set of "trial" states. The algorithm diagonalizes complex and symmetric (non-Hermitian) matrices and is easily implemented in modern computer languages. It is based on generalized Householder transformations and relies on iterative similarity transformations T ? T' = Q T T Q, where Q is a complex and orthogonal, but not unitary, matrix, i.e. Q T = Q -1 but Q + ? Q -1. We present numerical reference data to support the scalability of the algorithm. We construct the generalized Householder transformations from the notion that the conserved scalar product of eigenstates ? n and ? m of a pseudo-Hermitian quantum mechanical Hamiltonian can be reformulated in terms of the generalized indefinite inner product ? d x ? n ( x, t) ? m ( x, t), where the integrand is locally defined, and complex conjugation is avoided. A few example calculations are described which illustrate the physical origin of the ideas used in the construction of the algorithm.

Noble, J. H.; Lubasch, M.; Jentschura, U. D.

2013-08-01

21

Bounds for axially symmetric linear perturbations for the extreme Kerr black hole  

E-print Network

We obtain remarkably simple integral bounds for axially symmetric linear perturbations for the extreme Kerr black hole in terms of conserved energies. From these estimates we deduce pointwise bounds for the perturbations outside the horizon.

Sergio Dain; Ivan Gentile de Austria

2015-01-15

22

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

23

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

24

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

PubMed

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

2014-02-01

25

Two-dimensional complex parity-time-symmetric photonic structures  

NASA Astrophysics Data System (ADS)

We propose a simple realistic two-dimensional complex parity-time-symmetric photonic structure that is described by a non-Hermitian potential but possesses real-valued eigenvalues. The concept is developed from basic physical considerations to provide asymmetric coupling between harmonic wave components of the electromagnetic field. The structure results in a nonreciprocal chirality and asymmetric transmission between in- and out-coupling channels into the structure. The analytical results are supported by a numerical study of the Bloch-like mode formations and calculations of a realistic planar semiconductor structure.

Turduev, M.; Botey, M.; Giden, I.; Herrero, R.; Kurt, H.; Ozbay, E.; Staliunas, K.

2015-02-01

26

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

E-print Network

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 pointwise boundedness of the perturbation in a remarkable simple way.

Sergio Dain; Ivan Gentile de Austria

2014-09-19

27

MINRES-QLP for Singular Symmetric and Hermitian Linear ...  

E-print Network

Jan 12, 2013 ... or Hermitian linear systems or least-squares problems. If the system is ... 60637; email: sctchoi@uchicago.edu; M. A. Saunders, Department of Management Science and ...... the code is already linked to a BLAS library.

SOU-CHENG T. CHOI, MICHAEL A. SAUNDERS

2013-01-12

28

A new Krylov-subspace method for symmetric indefinite linear systems  

SciTech Connect

Many important applications involve the solution of large linear systems with symmetric, but indefinite coefficient matrices. For example, such systems arise in incompressible flow computations and as subproblems in optimization algorithms for linear and nonlinear programs. Existing Krylov-subspace iterations for symmetric indefinite systems, such as SYMMLQ and MINRES, require the use of symmetric positive definite preconditioners, which is a rather unnatural restriction when the matrix itself is highly indefinite with both many positive and many negative eigenvalues. In this note, the authors describe a new Krylov-subspace iteration for solving symmetric indefinite linear systems that can be combined with arbitrary symmetric preconditioners. The algorithm can be interpreted as a special case of the quasi-minimal residual method for general non-Hermitian linear systems, and like the latter, it produces iterates defined by a quasi-minimal residual property. The proposed method has the same work and storage requirements per iteration as SYMMLQ or MINRES, however, it usually converges in considerably fewer iterations. Results of numerical experiments are reported.

Freund, R.W. [AT and T Bell Labs., Murray Hill, NJ (United States); Nachtigal, N.M. [Oak Ridge National Lab., TN (United States). Mathematical Sciences Section

1994-10-01

29

A new solvable complex PT-symmetric potential  

E-print Network

We propose a new solvable one dimensional complex PT-symmetric potential as $V(x)= ig~ \\mbox{sgn}(x)~ |1-\\exp(2|x|/a)|$ and study the spectrum of $H=-d^2/dx^2+V(x)$. For smaller values of $a,g <1$, there are a finite number of real discrete eigenvalues. As $a$ and $g$ increase there exist exceptional points (EPs), $g_n$ (for fixed values of $a$) causing a scarcity of real discrete eigenvalues, but there exists at least one. We also show these real discrete eigenvalues as poles of reflection coefficient. We find that the energy-eigenstates $\\psi_n(x)$ satisfy (1): PT$\\psi_n(x)=1 \\psi_n(x)$ and (2): PT$\\psi_{E_n}(x)=\\psi_{E^*_n}(x)$, for real and complex energy-eigenvalues, respectively. The former is well known but the latter one has been generally missed out. Here, we prove this and also illustrate it in two more exactly solvable models.

Zafar Ahmed; Dona Ghosh; Joseph Amal Nathan

2015-02-17

30

A family of symmetric mixed finite elements for linear elasticity on tetrahedral grids  

NASA Astrophysics Data System (ADS)

A family of stable mixed finite elements for the linear elasticity on tetrahedral grids are constructed, where the stress is approximated by symmetric $H(\\d)$-$P_k$ polynomial tensors and the displacement is approximated by $C^{-1}$-$P_{k-1}$ polynomial vectors, for all $k\\ge 4$. Numerical tests are provided.

Hu, Jun; Zhang, ShangYou

2015-02-01

31

A self-adaptive projection and contraction method for monotone symmetric linear variational inequalities  

Microsoft Academic Search

In this paper, we present a self-adaptive projection and contraction (SAPC) method for solving symmetric linear variational inequalities. Preliminary numerical tests show that the proposed method is efficient and effective and depends only slightly on its initial parameter. The global convergence of the new method is also addressed.

Shengli Wang

2002-01-01

32

Solving symmetric indefinite systems in an interior-point method for linear programming  

Microsoft Academic Search

We describe an implementation of a primal—dual path following method for linear programming that solves symmetric indefinite “augmented” systems directly by Bunch—Parlett factorization, rather than reducing these systems to the positive definite “normal equations” that are solved by Cholesky factorization in many existing implementations. The augmented system approach is seen to avoid difficulties of numerical instability and inefficiency associated with

Robert Fourer; Sanjay Mehrotra

1993-01-01

33

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

SciTech Connect

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, E-mail: chienichiang@berkeley.edu, E-mail: izumi@phys.ntu.edu.tw, E-mail: chen@slac.stanford.edu [Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei 10617, Taiwan (China)

2012-12-01

34

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

35

The complexity of propositional linear temporal logics  

Microsoft Academic Search

The complexity of satisfiability and determination of truth in a particular finite structure are considered for different propositional linear temporal logics. It is shown that these problems are NP-complete for the logic with F and are PSPACE-complete for the logics with F, X, with U, with U, S, X operators and for the extended logic with regular operators given by

A. Prasad Sistla; Edmund M. Clarke

1985-01-01

36

Linear Complexity Hexahedral Mesh Generation David Eppstein  

E-print Network

cells are convex. To solve such a problem, one must typically add Steiner points interior to the polyhe to optimize the number of Steiner points) but one can efficiently find a set of O(n) Steiner pointsLinear Complexity Hexahedral Mesh Generation David Eppstein Department of Information and Computer

Eppstein, David

37

A Discontinuous Galerkin Method for Linear Symmetric Hyperbolic Systems in Inhomogeneous Media  

Microsoft Academic Search

The Discontinuous Galerkin (DG) method provides a powerful tool for approximating hyperbolic problems. Here we derive a new space-time DG method for linear time dependent hyperbolic problems written as a symmetric system (including the wave equation and Maxwell’s equations). The main features of the scheme are that it can handle inhomogeneous media, and can be time-stepped by solving a sequence

Peter Monk; Gerard R. Richter

2005-01-01

38

Buckling Behavior of Long Symmetrically Laminated Plates Subjected to Shear and Linearly Varying Axial Edge Loads  

NASA Technical Reports Server (NTRS)

A parametric study of the buckling behavior of infinitely long symmetrically laminated anisotropic plates that are subjected to linearly varying edge loads, uniform shear loads, or combinations of these loads is presented. The study focuses on the effects of the shape of linearly varying edge load distribution, plate orthotropy, and plate flexural anisotropy on plate buckling behavior. In addition, the study exmines the interaction of linearly varying edge loads and uniform shear loads with plate flexural anisotropy and orthotropy. Results obtained by using a special purpose nondimensional analysis that is well suited for parametric studies of clamped and simply supported plates are presented for [+/- theta](sub s), thin graphite-epoxy laminates that are representative of spacecraft structural components. Also, numerous generic buckling-design charts are presented for a wide range of nondimensional parameters that are applicable to a broad class of laminate constructions. These charts show explicitly the effects of flexural orthotropy and flexural anisotropy on plate buckling behavior for linearly varying edge loads, uniform shear loads, or combinations of these loads. The most important finding of the present study is that specially orthotropic and flexurally anisotropic plates that are subjected to an axial edge load distribution that is tension dominated can support shear loads that are larger in magnitude than the shear buckling load.

Nemeth, Michael P.

1997-01-01

39

Krylov subspace methods for complex non-Hermitian linear systems. Thesis  

NASA Technical Reports Server (NTRS)

We consider Krylov subspace methods for the solution of large sparse linear systems Ax = b with complex non-Hermitian coefficient matrices. Such linear systems arise in important applications, such as inverse scattering, numerical solution of time-dependent Schrodinger equations, underwater acoustics, eddy current computations, numerical computations in quantum chromodynamics, and numerical conformal mapping. Typically, the resulting coefficient matrices A exhibit special structures, such as complex symmetry, or they are shifted Hermitian matrices. In this paper, we first describe a Krylov subspace approach with iterates defined by a quasi-minimal residual property, the QMR method, for solving general complex non-Hermitian linear systems. Then, we study special Krylov subspace methods designed for the two families of complex symmetric respectively shifted Hermitian linear systems. We also include some results concerning the obvious approach to general complex linear systems by solving equivalent real linear systems for the real and imaginary parts of x. Finally, numerical experiments for linear systems arising from the complex Helmholtz equation are reported.

Freund, Roland W.

1991-01-01

40

Computational complexity of LCPs associated with positive definite symmetric matrices  

Microsoft Academic Search

Murty in a recent paper has shown that the computational effort required to solve a linear complementarity problem (LCP), by either of the two well known complementary pivot methods is not bounded above by a polynomial in the size of the problem. In that paper, by constructing a class of LCPs—one of ordern forn = 2—he has shown that to

Yahya Fathi

1979-01-01

41

Symmetric and asymmetric solitons in linearly coupled Bose-Einstein condensates trapped in optical lattices  

SciTech Connect

We study spontaneous symmetry breaking in a system of two parallel quasi-one-dimensional traps (cores), equipped with optical lattices (OLs) and filled with a Bose-Einstein condensate (BEC). The cores are linearly coupled by tunneling (the model may also be interpreted in terms of spatial solitons in parallel planar optical waveguides with a periodic modulation of the refractive index). Analysis of the corresponding system of linearly coupled Gross-Pitaevskii equations (GPEs) reveals that spectral band gaps of the single GPE split into subgaps. Symmetry breaking in two-component BEC solitons is studied in cases of the attractive (AA) and repulsive (RR) nonlinearity in both traps; the mixed situation, with repulsion in one trap and attraction in the other (RA), is considered too. In all the cases, stable asymmetric solitons are found, bifurcating from symmetric or antisymmetric ones (and destabilizing them), in the AA and RR systems, respectively. In either case, bistability is predicted, with a nonbifurcating stable branch, either antisymmetric or symmetric, coexisting with asymmetric ones. Solitons destabilized by the bifurcation tend to rearrange themselves into their stable asymmetric counterparts. In addition to the fundamental solitons, branches of twisted (odd) solitons in the AA system, and twisted bound states of fundamental solitons in both AA and RR systems, are found too. The impact of a phase mismatch, {delta}, between the OLs in the two cores is also studied. It is concluded that {delta}={pi}/2 only mildly deforms the picture, while {delta}={pi} changes it drastically, replacing the symmetry-breaking bifurcations by pseudobifurcations, with the branch of asymmetric solutions asymptotically approaching its symmetric or antisymmetric counterpart (in the AA and RR system, respectively), rather than splitting off from it. Also considered is a related model, for a binary BEC in a single-core trap with the OL, assuming that the two species (representing different spin states of the same atom) are coupled by linear interconversion. In that case, the symmetry-breaking bifurcations in the AA and RR models switch their character, if the interspecies nonlinear interaction becomes stronger than the intraspecies nonlinearity.

Gubeskys, Arthur; Malomed, Boris A. [Department of Interdisciplinary Studies, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)

2007-06-15

42

Analysis of the static properties of cluster formations in symmetric linear multiblock copolymers  

E-print Network

We use molecular dynamics simulations to study the static properties of a single linear multiblock copolymer chain under poor solvent conditions varying the block length $N$, the number of blocks $n$, and the solvent quality by variation of the temperature $T$. We study the most symmetrical case, where the number of blocks of monomers of type A, $n_{A}$, equals that of monomers B, $n_{B}$ ($n_{A}=n_{B}=n/2$), the length of all blocks is the same irrespective of their type, and potential parameters are also chosen symmetrically, as for a standard Lennard-Jones fluid. Under poor solvent conditions the chains collapse and blocks with monomers of the same type form clusters, which are phase separated from the clusters with monomers of the other type. We study the dependence of the size of the formed clusters on $n$, $N$ and $T$. Furthermore, we discuss our results with respect to recent simulation data on the phase behaviour of such macromolecules, providing a complete picture for the cluster formations in single multiblock copolymer chains under poor solvent conditions.

N. G. Fytas; P. E. Theodorakis

2011-04-22

43

Quasi-local variables, non-linear perturbations and back-reaction in spherically symmetric spacetimes  

E-print Network

We introduce a quasi-local integral functional and scalar quasi-local variables to examine a wide class of spherically symmetric inhomogeneous spacetimes that generalize the Lemaitre-Tolman-Bondi (LTB) dust solutions ("LTB" spacetimes). By using these variables, we can transform the fluid flow evolution equations into evolution equations for non-linear, covariant, gauge--invariant perturbations of Friedman-Lemaitre-Robertson-Walker (FLRW) cosmologies. In the linear limit, we obtain spherical perturbations in the synchronous gauge under the long wavelength approximation. The formalism has a significant potential for cosmological applications, as it allows one to examine a wide variety of sources with different "equations of state", generalizing known FLRW solutions to idealized but non-trivial and non-linear inhomogeneous conditions. The quasi-local functional can be reformulated as a weighed proper volume average distribution, with the weight factor given by a scalar invariant related to the quasi-local mass-energy function. The back-reaction terms, emerging in Buchert's proper averaging formalism, can be expressed as differences between fluctuations of averaged and quasi-local energy densities. By comparing this average with the weighed quasi-local one, we can define a binding energy functional related to spatial gradients of the averaged and quasi-local variables that appear in the back-reaction terms.

Roberto A Sussman

2008-09-19

44

Complex Spectrum of a Spontaneously Unbroken PT Symmetric Hamiltonian  

E-print Network

It is believed that unbroken PT symmetry is sufficient to guarantee that the spectrum of a non-Hermitian Hamiltonian is real. We prove that this is not true. We study a Hamiltonian with complex spectrum for which PT symmetry is not spontaneously broken.

C. Yuce

2007-03-25

45

On Computational Complexity of Counting Fixed Points in Symmetric Boolean Graph Automata  

Microsoft Academic Search

We study computational complexity of counting the fixed point con- figurations (FPs) in certain classes of graph automata viewed as discrete dy- namical systems. We prove that both exact and approximate counting of FPs in Sequential and Synchronous Dynamical Systems (SDSs and SyDSs, respec- tively) are computationally intractable, even when each node is required to update according to a symmetric

Predrag T. Tosica; Gul A. Agha

2005-01-01

46

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. Phys.: Condens. Matter 23 (2011) 235106 (9pp) doi:10.1088/0953-8984/23/23/235106 Analysis of the static properties of cluster formations in symmetric linear multiblock copolymers N G Fytas1 and P E Theodorakis2

Theodorakis, Panagiotis E.

47

Collision-induced absorption in mixtures of symmetrical linear and tetrahedral molecules - Methane-nitrogen  

NASA Technical Reports Server (NTRS)

The far infrared absorption of a CH4-N2 mixture was measured at 297, 195, and 162 K from 30 to 650/cm. The spectral invariants gamma1 and alpha1, proportional, respectively, to the zeroth and first spectral moments, due to bimolecular collisions between CH4 and N2 were obtained from these data and compared with theoretical values. The theory for collision-induced dipoles between a tetrahedral and a diatomic or symmetrical linear molecule includes contributions not previously considered. Whereas the theoretical values of gamma1 are only somewhat greater than experiment at all temperatures, the theoretical values of alpha1 are significantly lower than the experimental values. From the theoretical spectral moments for the various induced dipole components, the parameters of the BC shape were computed, and theoretical spectra were constructed. Good agreement was obtained at the lower frequencies, but with increasing frequencies the theoretical spectra were increasingly less intense than the experimental spectra. Although the accuracy of the theoretical results may suffer from the lack of a reliable potential function, it does not appear that this high frequency discrepancy can be removed by any conceivable modification in the potential.

Birnbaum, G.; Borysow, A.; Buechele, A.

1993-01-01

48

A Shared and Programmable Maximum-Confident Discrimination among Linearly Dependent Symmetric Qubit States  

NASA Astrophysics Data System (ADS)

We show how a shared and programmable maximum-confidence discrimination (SPMCD) can be implemented by two remote parters Alice and Bob. Here Bob is given a qubit prepared in one of N linearly dependent symmetric equiprobable states. Alice has the knowledge of Bob's signal states, but Bob has not. We build a quantum network that would be able to perform various desired maximum-confidence discrimination among Bob's measured (data) states depending on Alice's auxiliary (program) state. The SPMCD can be thought of as a two-step process, in which a two-outcome shared and programmable probability operator measure (POM) performed on data qubit B is firstly implemented by Alice and Bob followed by a N-outcome local POM on B implemented by Bob. We explicitly construct the required POMs. The fact that the nonlocal data-program conditional evolution, which induces the shared and programmable POM, can be realized deterministically using only two partially entangled qubit pairs is notable. The successful probability of implementing this SPMCD is optimal only for one program setting. However, for a relatively large set of program settings it can be very close to the optimal value in an ordinary, local, maximum-confidence discrimination. This protocol is feasible for current experimental technology.

Chen, LiBing; Lu, Hong

2014-11-01

49

The Computational Complexity of Linear Optics  

E-print Network

We give new evidence that quantum computers---moreover, rudimentary quantum computers built entirely out of linear-optical elements---cannot be efficiently simulated by classical computers. In particular, we define a model ...

Aaronson, Scott

2011-01-01

50

Symmetric and asymmetric solitons and vortices in linearly coupled two-dimensional waveguides with the cubic-quintic nonlinearity  

E-print Network

It is well known that the two-dimensional (2D) nonlinear Schr\\"odinger equation (NLSE) with the cubic-quintic (CQ) nonlinearity supports a family of stable fundamental solitons, as well as solitary vortices (alias vortex rings), which are stable for sufficiently large values of the norm. We study stationary localized modes in a symmetric linearly coupled system of two such equations, focusing on asymmetric states. The model may describe "optical bullets" in dual-core nonlinear optical waveguides (including spatiotemporal vortices that were not discussed before), or a Bose-Einstein condensate (BEC) loaded into a "dual-pancake" trap. Each family of solutions in the single-component model has two different counterparts in the coupled system, one symmetric and one asymmetric. Similarly to the earlier studied coupled 1D system with the CQ nonlinearity, the present model features bifurcation loops, for fundamental and vortex solitons alike: with the increase of the total energy (norm), the symmetric solitons become...

Dror, Nir

2010-01-01

51

A variant of the linear isotropic indeterminate couple stress model with symmetric local force-stress, symmetric nonlocal force-stress, symmetric couple-stresses and complete traction boundary conditions  

E-print Network

In this paper we venture a new look at the linear isotropic indeterminate couple stress model in the general framework of second gradient elasticity and we propose a new alternative formulation which obeys Cauchy-Boltzmann's axiom of the symmetry of the force stress tensor. For this model we prove the existence of solutions for the equilibrium problem. Relations with other gradient elastic theories and the possibility to switch from a {4th order} (gradient elastic) problem to a 2nd order micromorphic model are also discussed with a view of obtaining symmetric force-stress tensors. It is shown that the indeterminate couple stress model can be written entirely with symmetric force-stress and symmetric couple-stress. The difference of the alternative models rests in specifying traction boundary conditions of either rotational type or strain type. If rotational type boundary conditions are used in the partial integration, the classical anti-symmetric nonlocal force stress tensor formulation is obtained. Otherwise, the difference in both formulations is only a divergence--free second order stress field such that the field equations are the same, but the traction boundary conditions are different. For these results we employ a novel integrability condition, connecting the infinitesimal continuum rotation and the infinitesimal continuum strain. Moreover, we provide the complete, consistent traction boundary conditions for both models.

Ionel-Dumitrel Ghiba; Patrizio Neff; Angela Madeo; Ingo Münch

2015-04-03

52

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

53

Complex linear superfield as a model for Goldstino  

E-print Network

We propose a Goldstino model formulated in terms of a constrained complex linear superfield. Its comparison to other Goldstino models is given. Couplings to supersymmetric matter and supergravity are briefly described.

Sergei M. Kuzenko; Simon J. Tyler

2011-03-03

54

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

55

Passive control of the flow in a symmetric channel with a sudden expansion based on linear stability analysis  

NASA Astrophysics Data System (ADS)

In the present work we investigate the stability properties of the flow in a 2D-plane channel with a symmetric sudden expansion, which is a possible schematization of a plane diffuser. The laminar flow in 2D diffusers may produce either symmetric or nonsymmetric steady solutions, depending on the value of the Reynolds number Re as compared with some critical value Rec. The stability properties of the flow are studied in the context of linear theory, characterizing the sensitivity of the instability to both a structural perturbation of the linearized flow equations and a perturbation of the base flow. The information provided by the two kinds of analysis is used to propose a passive flow control strategy, obtained by the introduction of a small cylinder in the channel, aimed at stabilizing the symmetric solution at Re>Rec. The effectiveness of this control strategy in the nonlinear case is investigated, and ultimately verified by numerical simulations of the flow in which a real control cylinder is introduced. The robustness of the control is also tested by numerical simulations in which the position of the cylinder is slightly changed with respect to the optimal one given by the sensitivity analysis.

Fani, Andrea; Camarri, Simone; Salvetti, Maria-Vittoria

2011-11-01

56

EXPLICIT RUNGEKUTTA SCHEMES AND FINITE ELEMENTS WITH SYMMETRIC STABILIZATION FOR FIRST-ORDER LINEAR  

E-print Network

EXPLICIT RUNGE­KUTTA SCHEMES AND FINITE ELEMENTS WITH SYMMETRIC STABILIZATION FOR FIRST Runge­Kutta schemes in time combined with stabilized finite elements in space to approximate evolution discretization, we consider explicit second- and third-order Runge­Kutta schemes. We identify a general set

57

Reducing the parallel complexity of certain linear programming problems  

Microsoft Academic Search

The parallel complexity of solving linear programming problems is studied in the context of interior point methods. If n and m, respectively, denote the number of variables and the number of constraints in the given problem, an algorithm that solves linear programming problems in O((mn)1\\/4 (log 1 n)3L) time using O(M(n)m\\/n+1n3 ) processors is given. (M(n) is the number of

Pravin M. Vaidya

1990-01-01

58

A C Symmetric Nitrate Complex with a Thiophene-Based Tripodal Receptor.  

PubMed

A thiophene-based tripodal receptor has been synthesized and its complexes with nitrate and iodide have determined by single-crystal X-ray analysis. In the nitrate complex, one nitrate is encapsulated in a selective orientation forming a C(3) symmetric complex, which is bonded to three protonated secondary amines with six NH···O bonds. The anion is coordinated in a plane perpendicular to the principal rotation axis passing through the tertiary nitrogen of the receptor and the nitrogen of the encapsulated nitrate. High-level DFT calculations support the crystallographic results demonstrating that an adduct with trigonal binding of three oxygen atoms is more stable than that of one oxygen atom of the encapsulate nitrate. On the other hand, in the structure of the iodide complex, all three iodides lie outside the cavity. (1)H NMR titration studies indicate that the receptor forms a 1:1 complex with nitrate with a binding constant of K = 315 M(-1) in chloroform, showing a moderate selectivity over halides and perchlorate. PMID:21552352

I?iklan, Muhammet; Saeed, Musabbir A; Pramanik, Avijit; Wong, Bryan M; Fronczek, Frank R; Hossain, Alamgir

2011-04-01

59

Slice-selective J-coupled coherence transfer using symmetric linear phase pulses: applications to localized GABA spectroscopy  

NASA Astrophysics Data System (ADS)

Symmetric, linear phase, slice-selective RF pulses were analyzed theoretically for performing slice-selective coherence transfer. It was shown using numerical simulations of product operators that, when a prefocusing gradient of the same area as that of the refocusing gradient is added, these pulses become slice-selective universal rotator pulses, therefore, capable of performing slice-selective coherence transfer. As an example, a slice-selective universal rotator pulse based on a seven-lobe hamming-filtered sinc pulse was applied to in vivo single-shot simultaneous spectral editing and spatial localization of neurotransmitter GABA in the human brain.

Shen, Jun

2003-07-01

60

General theory of spherically symmetric boundary-value problems of the linear transport theory.  

NASA Technical Reports Server (NTRS)

A general theory of spherically symmetric boundary-value problems of the one-speed neutron transport theory is presented. The formulation is also applicable to the 'gray' problems of radiative transfer. The Green's function for the purely absorbing medium is utilized in obtaining the normal mode expansion of the angular densities for both interior and exterior problems. As the integral equations for unknown coefficients are regular, a general class of reduction operators is introduced to reduce such regular integral equations to singular ones with a Cauchy-type kernel. Such operators then permit one to solve the singular integral equations by the standard techniques due to Muskhelishvili. We discuss several spherically symmetric problems. However, the treatment is kept sufficiently general to deal with problems lacking azimuthal symmetry. In particular the procedure seems to work for regions whose boundary coincides with one of the coordinate surfaces for which the Helmholtz equation is separable.

Kanal, M.

1972-01-01

61

Complex limbal choristomas in linear nevus sebaceous syndrome  

Microsoft Academic Search

ObjectiveThis study aimed to describe the clinical and histopathologic findings in four patients with complex limbal choristomas associated with linear nevus sebaceous syndrome (LNSS), a rare disorder including nevus sebaceous, seizures, and mental retardation, and often accompanied by ocular anomalies.

Jacque L Duncan; Mahin Golabi; Douglas R Fredrick; Creig S Hoyt; David G Hwang; Steven G Kramer; Edward L Howes; Emmett T Cunningham

1998-01-01

62

Solving symmetric monotone linear variational inequalities by some modified Levitin-Polyak projection methods  

Microsoft Academic Search

Some modified Levitin-Polyak projection methods are proposed in this paper for solving monotone linear variational inequality\\u000a x ? ?,(x-x)T(hx+c+ c)?0, ?x ? ?. It is pointed out that there are similar methods for solving a general linear variational inequality.

Gao Yi

1998-01-01

63

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

64

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

PubMed

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 is a VL domain that binds malachite green (MG) dye 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 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 1000-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, Sarah; Waggoner, Alan S; Wilson, Ian A; Bruchez, Marcel P

2013-11-15

65

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

66

Linear Complexity Lossy Compressor for Binary Redundant Memoryless Sources  

E-print Network

A lossy compression algorithm for binary redundant i.i.d. sources is presented. The proposed scheme is based on sparse graph codes. By introducing a nonlinear function, redundant memoryless sequences can be compressed. We propose a linear complexity compressor based on the extended belief propagation, into which an inertia term is heuristically introduced, and show that it has near optimal performance for moderate blocklengths.

Mimura, Kazushi

2011-01-01

67

A ubiquitin ligase complex assembles linear polyubiquitin chains  

PubMed Central

The ubiquitin system plays important roles in the regulation of numerous cellular processes by conjugating ubiquitin to target proteins. In most cases, conjugation of polyubiquitin to target proteins regulates their function. In the polyubiquitin chains reported to date, ubiquitin monomers are linked via isopeptide bonds between an internal Lys and a C-terminal Gly. Here, we report that a protein complex consisting of two RING finger proteins, HOIL-1L and HOIP, exhibits ubiquitin polymerization activity by recognizing ubiquitin moieties of proteins. The polyubiquitin chain generated by the complex is not formed by Lys linkages, but by linkages between the C- and N-termini of ubiquitin, indicating that the ligase complex possesses a unique feature to assemble a novel head-to-tail linear polyubiquitin chain. Moreover, the complex regulates the stability of Ub-GFP (a GFP fusion protein with an N-terminal ubiquitin). The linear polyubiquitin chain generated post-translationally may function as a new modulator of proteins. PMID:17006537

Kirisako, Takayoshi; Kamei, Kiyoko; Murata, Shigeo; Kato, Michiko; Fukumoto, Hiromi; Kanie, Masato; Sano, Soichi; Tokunaga, Fuminori; Tanaka, Keiji; Iwai, Kazuhiro

2006-01-01

68

Trellis complexity bounds for decoding linear block codes  

NASA Technical Reports Server (NTRS)

We consider the problem of finding a trellis for a linear block code that minimizes one or more measures of trellis complexity. The domain of optimization may be different permutations of the same code or different codes with the same parameters. Constraints on trellises, including relationships between the minimal trellis of a code and that of the dual code, are used to derive bounds on complexity. We define a partial ordering on trellises: If a trellis is optimum with respect to this partial ordering, if has the desirable property that it simultaneously minimizes all of the complexity measures examined. We examine properties of such optimal trellises and give examples of optimal permutations of codes, most notably the (48,24,12) quadratic residue code.

Kiely, A. B.; Dolinar, S.; Ekroot, L.; Mceliece, R. J.; Lin, W.

1995-01-01

69

Orientation and linear dichroism characteristics of porphyrin-DNA complexes  

SciTech Connect

The linear dichroism spectra of complexes of tetrakis(N-methyl-4-pyridinio)porphine (H/sub 2/TMpyP) and its zinc(II) derivative (ZnTMpyP) with DNA oriented in a flow gradient have been investigated. The dichroism of H/sub 2/TMpyP determined within the Soret band and the Q/sub y/ band system is consistent with an intercalative conformation in which the plane of the porphyrin ring system is nearly parallel to the planes of the DNA bases. In the case of ZnTMpyP on the other hand, the porphyrin ring system is inclined at angles of 62-67/sup 0/ with respect to the axis of the DNA helix. The pyridyl groups in both cases are characterized by a low degree of orientation with respect to the axis of the helix. In contrast to H/sub 2/TMpyP which does not significantly affect the degree of alignment of the DNA in the flow gradient, the binding of ZnTMpyP causes a significant decrease (about 50% for a base pair/ZnTMpyP ratio of 20) in the intrinsic dichroism at 260 nm due to the oriented DNA bases; the binding of ZnTMpyP to DNA either gives rise to regions of higher flexibility or causes bends or kinks at the binding sites. Increasing the ionic strength has little influence on the linear dichroism of the ZnTMpyP-DNA complexes, but the number of molecules bound at intercalation sites diminishes in the case of the H/sub 2/TMpyP-DNA complexes; the accompanying changes in the linear dichroism characteristics suggest that external H/sub 2/TMpyP complexes are formed at the expense of intercalation complexes. Taken together, these linear dichroism results are consistent with the intercalative model for H/sub 2/TMpyP-DNA and the external binding model for ZnTMpyP-DNA complexes proposed by Fiel et al and Pasternack et al.

Geacintov, N.E.; Ibanez, V.; Rougee, M.; Bensasson, R.V.

1987-06-02

70

Complexity of necessary efficiency in interval linear programming and multiobjective linear programming  

Microsoft Academic Search

We present some complexity results on checking necessary efficiency in interval multiobjective linear programming. Supposing\\u000a that objective function coefficients perturb within prescribed intervals, a feasible point x* is called necessarily efficient if it is efficient for all instances of interval data. We show that the problem of checking\\u000a necessary efficiency is co-NP-complete even for the case of only one objective.

Milan Hladík

71

CMISTARK: Python package for the Stark-effect calculation and symmetry classification of linear, symmetric and asymmetric top wavefunctions in dc electric fields  

NASA Astrophysics Data System (ADS)

The Controlled Molecule Imaging group (CMI) at the Center for Free Electron Laser Science (CFEL) has developed the CMISTARK software to calculate, view, and analyze the energy levels of adiabatic Stark energy curves of linear, symmetric top and asymmetric top molecules. The program exploits the symmetry of the Hamiltonian to generate fully labeled adiabatic Stark energy curves.

Chang, Yuan-Pin; Filsinger, Frank; Sartakov, Boris G.; Küpper, Jochen

2014-01-01

72

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

2014-12-01

73

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

74

Chiral platinum and palladium complexes containing functionalized C 2-symmetric bisaminoaryl ‘Pincer’ ligands  

Microsoft Academic Search

The synthesis of enantiopure (oxo-functionalized) C2-symmetric NCN pincer ligands is described. A key step is the symmetric functionalization of the benzylic positions, which was achieved by enantioselective ketone reduction and subsequent stereoselective substitution protocols. The introduction of ?-alkyl substituents has a pronounced effect on the cavity for metal binding. For example, lithiation of the ?-ethyl-functionalized pincer ligand afforded mixed (alkyl)(aryl)lithium

Martin Albrecht; Betty M Kocks; Anthony L Spek; Gerard van Koten

2001-01-01

75

The complex structure of Abell 2345: a galaxy cluster with non-symmetric radio relics  

NASA Astrophysics Data System (ADS)

Context. The connection of cluster mergers with the presence of extended, diffuse radio sources in galaxy clusters is still debated. Aims: We aim to obtain new insights into the internal dynamics of the cluster Abell 2345. This cluster exhibits two non-symmetric radio relics well studied through recent, deep radio data. Methods: Our analysis is based on redshift data for 125 galaxies acquired at the Telescopio Nazionale Galileo and on new photometric data acquired at the Isaac Newton Telescope. We also use ROSAT/HRI archival X-ray data. We combine galaxy velocities and positions to select 98 cluster galaxies and analyze the internal dynamics of the cluster. Results: We estimate a mean redshift < z > = 0.1789 and a line-of-sight (LOS) velocity dispersion ?V ~ 1070 km s-1. The two-dimensional galaxy distribution reveals the presence of three significant peaks within a region of ~1 h70-1 Mpc (the E, NW, and SW peaks). The spectroscopic catalog confirms the presence of these three clumps. The SW and NW clumps have similar mean velocities, while the E clump has a larger mean velocity (? Vrf ~ 800 km s-1); this structure causes the presence of the two peaks we find in the cluster velocity distribution. The difficulty in separating the galaxy clumps leads to a very uncertain mass estimate M ~ 2 × 1015 h70-1 M?. Moreover, the E clump well coincides with the main mass peak as recovered from the weak gravitational lensing analysis and is off-set to the east from the BCG by ~1.3´. The ROSAT X-ray data also show a very complex structure, mainly elongated in the E-W direction, with two (likely three) peaks in the surface brightness distribution, which, however, are off-set from the position of the peaks in the galaxy density. The observed phenomenology agrees with the hypothesis that we are looking at a complex cluster merger occurring along two directions: a major merger along the ~E-W direction (having a component along the LOS) and a minor merger in the western cluster regions along the ~N-S direction, roughly parallel to the plane of the sky. The eastern radio relic is elongated in the direction perpendicular to that of the major merger, while the peculiar, western radio relic is elongated in the direction perpendicular to the bisecting of the two merger directions. Conclusions: Our scenario for the internal dynamics of Abell 2345 strongly supports the use of the “outgoing merger shocks” model to explain the two radio relics, suggesting a consistent justification for their asymmetry. Table 1 is only available in electronic form at http://www.aanda.org

Boschin, W.; Barrena, R.; Girardi, M.

2010-10-01

76

On complexity of trellis structure of linear block codes  

NASA Technical Reports Server (NTRS)

The trellis structure of linear block codes (LBCs) is discussed. The state and branch complexities of a trellis diagram (TD) for a LBC is investigated. The TD with the minimum number of states is said to be minimal. The branch complexity of a minimal TD for a LBC is expressed in terms of the dimensions of specific subcodes of the given code. Then upper and lower bounds are derived on the number of states of a minimal TD for a LBC, and it is shown that a cyclic (or shortened cyclic) code is the worst in terms of the state complexity among the LBCs of the same length and dimension. Furthermore, it is shown that the structural complexity of a minimal TD for a LBC depends on the order of its bit positions. This fact suggests that an appropriate permutation of the bit positions of a code may result in an equivalent code with a much simpler minimal TD. Boolean polynomial representation of codewords of a LBC is also considered. This representation helps in study of the trellis structure of the code. Boolean polynomial representation of a code is applied to construct its minimal TD. Particularly, the construction of minimal trellises for Reed-Muller codes and the extended and permuted binary primitive BCH codes which contain Reed-Muller as subcodes is emphasized. Finally, the structural complexity of minimal trellises for the extended and permuted, and double-error-correcting BCH codes is analyzed and presented. It is shown that these codes have relatively simple trellis structure and hence can be decoded with the Viterbi decoding algorithm.

Lin, Shu

1990-01-01

77

On the Complexities of Linear LL(1) and LR(1) Grammars  

Microsoft Academic Search

Several notions of deterministic linear languages are considered and comparedwith respect to their complexities and to the families of formal languages theygenerate. We exhibit close relationships between simple linear languages and thedeterministic linear languages both according to Nasu and Honda and to Ibarra,Jiang, and Ravikumar. Deterministic linear languages turn out to be special casesof languages generated by linear grammars restricted

Markus Holzer; Klaus-jörn Lange

1993-01-01

78

Linear Viscoelasticity and Swelling of Polyelectrolyte Complex Coacervates  

NASA Astrophysics Data System (ADS)

The addition of near equimolar amounts of poly(diallyldimethylammonium chloride) to poly(isobutylene-alt-maleate sodium), results in formation of a polyelectrolyte complex coacervate. Zeta-potential titrations conclude that these PE-complexes are nearly charge-neutral. Swelling and rheological properties are studied at different salt concentrations in the surrounding solution. The enhanced swelling observed at high salt concentration suggests the system behaves like a polyampholyte gel, and weaker swelling at very low salt concentrations implies polyelectrolyte gel behavior. Linear viscoelastic oscillatory shear measurements indicate that the coacervates are viscoelastic liquids and that increasing ionic strength of the medium weakens the electrostatic interactions between charged units, lowering the relaxation time and viscosity. We use the time-salt superposition idea recently proposed by Spruijt, et al., allowing us to construct master curves for these soft materials. Similar swelling properties observed when varying molecular weights. Rheological measurements reveal that PE-complexes with increasing molecular weight polyelectrolytes form a network with higher crosslink density, suggesting time-molecular weight superposition idea.

Hamad, Fawzi; Colby, Ralph

2012-02-01

79

Journal home page: http://www.sciencedirect.com/science/journal/00457949 Stability analysis and non-linear behaviour of structural systems using the complex non-linear modal  

E-print Network

and non-linear behaviour of structural systems using the complex non-linear modal analysis (CNLMA and L. Jezequel STABILITY ANALYSIS AND NON-LINEAR BEHAVIOUR OF STRUCTURAL SYSTEMS USING THE COMPLEX NON-LINEAR. ABSTRACT Herein, a novel non-linear procedure for producing non-linear behaviour and stable limit cycle

Paris-Sud XI, Université de

80

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

81

On the experimental verification of quantum complexity in linear optics  

NASA Astrophysics Data System (ADS)

Quantum computers promise to solve certain problems that are forever intractable to classical computers. The first of these devices are likely to tackle bespoke problems suited to their own particular physical capabilities. Sampling the probability distribution from many bosons interfering quantum-mechanically is conjectured to be intractable to a classical computer but solvable with photons in linear optics. However, the complexity of this type of problem means its solution is mathematically unverifiable, so the task of establishing successful operation becomes one of gathering sufficiently convincing circumstantial or experimental evidence. Here, we develop scalable methods to experimentally establish correct operation for this class of computation, which we implement for three, four and five photons in integrated optical circuits, on Hilbert spaces of up to 50,000 dimensions. Our broad approach is practical for all quantum computational architectures where formal verification methods for quantum algorithms are either intractable or unknown.

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

2014-08-01

82

Implementation of Simplicial Complexes for CPA functions in C++11 using the Armadillo Linear Algebra Library  

E-print Network

linear, nonlinear system, triangulation, simplicial complex, C++11, Armadillo linear algebra library linear algebra library. Es- pecially, we discuss some of the new language features in C++11 that lead, and the linking to and use of the excellent Armadillo linear algebra library. Thus, some parts of this paper

Hafstein, Sigurður Freyr

83

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

84

Use of Complex Lie Symmetries for Linearization of Systems of Differential Equations - I: Ordinary Differential Equations  

Microsoft Academic Search

The Lie linearizability criteria are extended to complex functions for complex ordinary differential equations. The linearizability of complex ordinary differential equations is used to study the linearizability of corresponding systems of two real ordinary differential equations. The transformations that map a system of two nonlinear ordinary differential equations into systems of linear ordinary differential equations are obtained from complex transformations.

S. Ali; F. M. Mahomed; Asghar Qadir

2007-01-01

85

Complexity of monodic guarded fragments over linear and real time  

E-print Network

that the monodic fragments based on all these first-order frag- ments are decidable over a wide range of linear of monodic frag- ments has begun. In [13], it was shown that the one-variable fragment of linear first- order

Hodkinson, Ian

86

Complex Non-Linear Modal Analysis for Mechanical Systems: Application to Turbomachinery Bladings With Friction  

E-print Network

Complex Non-Linear Modal Analysis for Mechanical Systems: Application to Turbomachinery Bladings.laxalde@ec-lyon.fr, fabrice.thouverez@ec-lyon.fr Abstract A method for modal analysis of non-linear and non-conservative mechanical systems is proposed. In particular, dry-friction non-linearities are considered although

Paris-Sud XI, Université de

87

Reasoning About Knowledge In Linear Logic: Modalities and Complexity  

Microsoft Academic Search

In this paper, we briefly argue, following ideas set forth by Jacques Dubucs, for a radical version of anti-realism and claim\\u000a that it leads to the adoption of a ‘substructural’ logic, linear logic. We further argue that, in order to avoids problems\\u000a such as that of ‘omniscience’, one should develop an epistemic linear logic, which would be weak enough so

Mathieu Marion; Mehrnouche Sadrzadeh

88

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

89

New Complexity Analysis of IIPMs for Linear Optimization Based on ...  

E-print Network

Jun 20, 2005 ... Primal-dual Interior-Point Methods (IPMs) have shown their ability in ... The landmark paper of Karmarkar [3] revitalized Linear Optimization ... Recently, a new variant of feasible IPMs based on Self-Regular ... Numerical experiences ...... programming, Computational Optimization and Applications, 6, pp.

2005-06-20

90

The linear and nonlinear rheology of multiscale complex fluids  

E-print Network

The microstructures of many complex fluids are typically characterized by a broad distribution of internal length scales. Examples of such multiscale materials include physically and chemically cross-linked gels, emulsions, ...

Jaishankar, Aditya

2014-01-01

91

A compact symmetric feature detector for face localization in complex background  

NASA Astrophysics Data System (ADS)

Human face localization in an image is a key component in many intelligent applications. A compact face detecting method, especially suitable for multiple faces in a complex background, is proposed in this paper based on the symmetry property of the face and facial organs. The detector has a low computation load, a simultaneous localizing capability and is robust to bad illumination. Experiments show the effectiveness of the algorithm so it is potentially useful in related intelligent applications.

Li, Ruonan; Zhang, Xudong

2005-10-01

92

Glyphosate and ATP binding by mononuclear Zn(II) complexes with non-symmetric ditopic polyamine ligands.  

PubMed

Binding of Zn(II) by the ditopic ligands L1py, L2py and L1para, composed of a cyclam unit linked to the linear polyamines 1,4,8,11-tetraazaundecane (L1py and L2para) and 1,4,7-triazaheptane (L2py) via a 2,6-dimethylpyridinyl (L1py and L2py) or a 1,4-dimethylbenzyl spacer (L2para), has been analyzed by means of potentiometric and (1)H and (13)C NMR measurements. All ligands form stable mononuclear Zn(II) complexes in a wide pH range, featuring the metal ion bound to the macrocyclic unit. The open-chain polyamine unit can easily bind several protons in aqueous solution affording protonated metal complexes at neutral and acidic pH values. These complexes behave as bifunctional receptors for the anionic substrates N-(phosphonomethyl)glycine (glyphosate or PMG) and ATP. Potentiometric, (1)H and (31)P NMR measurements show that the Zn(II) complex with L1py is the better receptor for both substrates, thanks to the simultaneous presence of a pyridine linker functionalized at its 2,6 positions and of a flexible linear tetraamine chain. In fact, these structural features allow a stronger interaction of PMG and ATP with both the protonated tetraamine moiety and the Zn(II)-cyclam core. PMID:22785253

Pouessel, Jacky; Le Bris, Nathalie; Bencini, Andrea; Giorgi, Claudia; Valtancoli, Barbara; Tripier, Raphaël

2012-09-21

93

Towards Low-Complexity Linear-Programming Decoding  

Microsoft Academic Search

We consider linear-programming (LP) decoding of low-density parity-check (LDPC) codes. While it is clear that one can use any general-purpose LP solver to solve the LP that appears in the decoding problem, we argue in this paper that the LP at hand is equipped with a lot of structure that one should take advantage of. Towards this goal, we study

Pascal O. Vontobel; Ralf Koetter

2006-01-01

94

Radical localization in a series of symmetric Ni(II) complexes with oxidized salen ligands.  

PubMed

Square-planar nickel(II) complexes of salen ligands, N,N'-bis(3-tert-butyl-(5R)-salicylidene)-1,2-cyclohexanediamine), in which R=tert-butyl (1), OMe (2), and NMe(2) (3), were prepared and the electronic structure of the one-electron-oxidized species [1-3](+·) was investigated in solution. Cyclic voltammograms of [1-3] showed two quasi-reversible redox waves that were assigned to the oxidation of the phenolate moieties to phenoxyl radicals. From the difference between the first and second redox potentials, the trend of electronic delocalization 1(+·) >2(+·) >3(+·) was obtained. The cations [1-3](+·) exhibited isotropic g tensors of 2.045, 2.023, and 2.005, respectively, reflecting a lower metal character of the singly occupied molecular orbital (SOMO) for systems that involve strongly electron-donating substituents. Pulsed-EPR spectroscopy showed a single population of equivalent imino nitrogen atoms for 1(+·), whereas two distinct populations were observed for 2(+·). The resonance Raman spectra of 2(+·) and 3(+·) displayed the ?(8a) band of the phenoxyl radicals at 1612 cm(-1), as well as the ?(8a) bands of the phenolates. In contrast, the Raman spectrum of 1(+·) exhibited the ?(8a) band at 1602 cm(-1), without any evidence of the phenolate peak. Previous work showed an intense near-infrared (NIR) electronic transition for 1(+·) (??(1/2) =660 cm(-1), ?=21,700 M(-1) cm(-1)), indicating that the electron hole is fully delocalized over the ligand. The broader and moderately intense NIR transition of 2(+·) (??(1/2) =1250 cm(-1) , ?=12,800 M(-1) cm(-1)) suggests a certain degree of ligand-radical localization, whereas the very broad NIR transition of 3(+·) (??(1/2) =8630 cm(-1), ?=2550 M(-1) cm(-1)) indicates significant localization of the ligand radical on a single ring. Therefore, 1(+·) is a Class III mixed-valence complex, 2(+·) is Class II/III borderline complex, and 3(+·) is a Class II complex according to the Robin-Day classification method. By employing the Coulomb-attenuated method (CAM-B3LYP) we were able to predict the electron-hole localization and NIR transitions in the series, and show that the energy match between the redox-active ligand and the metal d orbitals is crucial for delocalization of the radical SOMO. PMID:22997000

Chiang, Linus; Kochem, Amélie; Jarjayes, Olivier; Dunn, Tim J; Vezin, Hervé; Sakaguchi, Miyuki; Ogura, Takashi; Orio, Maylis; Shimazaki, Yuichi; Thomas, Fabrice; Storr, Tim

2012-10-29

95

Approximation and inversion of a complex meteorological system via local linear filters  

E-print Network

Approximation and inversion of a complex meteorological system via local linear filters Frederic to describe meteorological behavior. Approximations to such systems are often desired, particularly an adequate summary of the relationship among certain urban and meteorological variables. However, one problem

Schoenberg, Frederic Paik (Rick)

96

On non-linear lower bounds in computational complexity  

Microsoft Academic Search

The purpose of this paper is to explore the possibility that purely graph-theoretic reasons may account for the superlinear complexity of wide classes of computational problems. The results are therefore of two kinds: reductions to graph theoretic conjectures on the one hand, and graph theoretic results on the other. We show that the graph of any algorithm for any one

Leslie G. Valiant

1975-01-01

97

Characterization of a potentially axially symmetric europium(III) complex of a tetraacetate,tetraaza, macrocyclic ligand by luminescence excitation, emission and lifetime spectroscopy  

NASA Astrophysics Data System (ADS)

The Eu(III) complex of the octadentate macrocyclic ligand, 1,4,7,10-tetraazacyclododecane-N,N',N'',N''' -tetraacetate, DOTA, has been examined by luminescence excitation, emission, and lifetime spectroscopy using pulsed dye laser techniques. The results confirm the expected axially symmetric nature of the major component in solution and reveal that 1.2 ± 0.4 water molecules arc coordinatcd to the Eu(III) ion in the complex.

Albin, Michael; de, William; Horrocks, W., Jr.; Liotta, Frank J.

1982-01-01

98

Magnetic blocking in a linear iron(I) complex  

NASA Astrophysics Data System (ADS)

Single-molecule magnets that contain one spin centre may represent the smallest possible unit for spin-based computational devices. Such applications, however, require the realization of molecules with a substantial energy barrier for spin inversion, achieved through a large axial magnetic anisotropy. Recently, significant progress has been made in this regard by using lanthanide centres such as terbium(III) and dysprosium(III), whose anisotropy can lead to extremely high relaxation barriers. We contend that similar effects should be achievable with transition metals by maintaining a low coordination number to restrict the magnitude of the d-orbital ligand-field splitting energy (which tends to hinder the development of large anisotropies). Herein we report the first two-coordinate complex of iron(I), [Fe(C(SiMe3)3)2]-, for which alternating current magnetic susceptibility measurements reveal slow magnetic relaxation below 29 K in a zero applied direct-current field. This S = complex exhibits an effective spin-reversal barrier of Ueff = 226(4) cm-1, the largest yet observed for a single-molecule magnet based on a transition metal, and displays magnetic blocking below 4.5 K.

Zadrozny, Joseph M.; Xiao, Dianne J.; Atanasov, Mihail; Long, Gary J.; Grandjean, Fernande; Neese, Frank; Long, Jeffrey R.

2013-07-01

99

Magnetic blocking in a linear iron(I) complex.  

PubMed

Single-molecule magnets that contain one spin centre may represent the smallest possible unit for spin-based computational devices. Such applications, however, require the realization of molecules with a substantial energy barrier for spin inversion, achieved through a large axial magnetic anisotropy. Recently, significant progress has been made in this regard by using lanthanide centres such as terbium(III) and dysprosium(III), whose anisotropy can lead to extremely high relaxation barriers. We contend that similar effects should be achievable with transition metals by maintaining a low coordination number to restrict the magnitude of the d-orbital ligand-field splitting energy (which tends to hinder the development of large anisotropies). Herein we report the first two-coordinate complex of iron(I), [Fe(C(SiMe3)3)2](-), for which alternating current magnetic susceptibility measurements reveal slow magnetic relaxation below 29 K in a zero applied direct-current field. This S =  complex exhibits an effective spin-reversal barrier of Ueff = 226(4) cm(-1), the largest yet observed for a single-molecule magnet based on a transition metal, and displays magnetic blocking below 4.5 K. PMID:23787747

Zadrozny, Joseph M; Xiao, Dianne J; Atanasov, Mihail; Long, Gary J; Grandjean, Fernande; Neese, Frank; Long, Jeffrey R

2013-07-01

100

Hierarchical self-assembling of dendritic–linear diblock complex based on hydrogen bonding  

Microsoft Academic Search

An effective route was demonstrated to fabricate vesicles, cylindrical micelles, fibers and hierarchical structures by using dendritic–linear amphiphilic diblock complex as building block through hydrogen bonding. We tailored the formation and evolution of these aggregation morphologies as well as the transformation among them, and found that the concentration and solvent polarity could affect the aggregation states of the complex in

Qingtao Liu; Hui Zhang; Shengyan Yin; Lixin Wu; Chen Shao; Zhongmin Su

2007-01-01

101

Complex Craniofacial Changes in Blind Cave-Dwelling Fish Are Mediated by Genetically Symmetric and Asymmetric Loci  

PubMed Central

The genetic regulators of regressive craniofacial morphologies are poorly understood. To shed light on this problem, we examined the freshwater fish Astyanax mexicanus, a species with surface-dwelling and multiple independent eyeless cave-dwelling forms. Changes affecting the skull in cavefish include morphological alterations to the intramembranous circumorbital bones encircling the eye. Many of these modifications, however, have evolved separately from eye loss, such as fragmentation of the third suborbital bone. To understand the genetic architecture of these eye-independent craniofacial alterations, we developed and scored 33 phenotypes in the context of an F2 hybrid mapping pedigree bred from Pachón cavefish and surface fish. We discovered several individuals exhibiting dramatic left–right differences in bone formation, such as extensive fragmentation on the right side only. This observation, along with well-known eye size asymmetry in natural cave-dwelling animals, led us to further evaluate left–right genetic differences for the craniofacial complex. We discovered three phenotypes, inclusive of bone fragmentation and fusion, which demonstrated a directional heritable basis only on one side. Interestingly, the overall areas of affected bones were genetically symmetric. Phenotypic effect plots of these novel craniofacial QTL revealed that cave alleles are associated with abnormal conditions such as bony fusion and fragmentation. Moreover, many linked loci overlapped with other cave-associated traits, suggesting regressive craniofacial changes may evolve through linkage or as antagonistic pleiotropic consequences of cave-associated adaptations. These novel findings illuminate significant craniofacial changes accompanying evolution in complete darkness and reveal complex changes to the skull differentially influenced by genetic changes affecting the left and right sides. PMID:24496009

Gross, Joshua B.; Krutzler, Amanda J.; Carlson, Brian M.

2014-01-01

102

A nonlocal connection between certain linear and nonlinear ordinary differential equations - Part II: Complex nonlinear oscillators  

E-print Network

In this paper, we present a method to identify integrable complex nonlinear oscillator systems and construct their solutions. For this purpose, we introduce two types of nonlocal transformations which relate specific classes of nonlinear complex ordinary differential equations (ODEs) with complex linear ODEs, thereby proving the integrability of the former. We also show how to construct the solutions using the two types of nonlocal transformations with several physically interesting cases as examples.

R. Mohanasubha; Jane H. Sheeba; V. K. Chandrasekar; M. Senthilvelan; M. Lakshmanan

2013-09-12

103

Design of in vitro symmetric complexes and analysis by hybrid methods reveal mechanisms of HIV capsid assembly.  

PubMed

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 the synergy of hybrid methods in structural biology, a powerful approach for exploring the structure of pleomorphic macromolecular complexes. PMID:21762799

Yeager, Mark

2011-07-22

104

PT-symmetric strings  

SciTech Connect

We study both analytically and numerically the spectrum of inhomogeneous strings with PT-symmetric density. We discuss an exactly solvable model of PT-symmetric string which is isospectral to the uniform string; for more general strings, we calculate exactly the sum rules Z(p)??{sub n=1}{sup ?}1/E{sub n}{sup p}, with p=1,2,… and find explicit expressions which can be used to obtain bounds on the lowest eigenvalue. A detailed numerical calculation is carried out for two non-solvable models depending on a parameter, obtaining precise estimates of the critical values where pair of real eigenvalues become complex. -- Highlights: •PT-symmetric Hamiltonians exhibit real eigenvalues when PT symmetry is unbroken. •We study PT-symmetric strings with complex density. •They exhibit regions of unbroken PT symmetry. •We calculate the critical parameters at the boundaries of those regions. •There are exact real sum rules for some particular complex densities.

Amore, Paolo, E-mail: paolo.amore@gmail.com [Facultad de Ciencias, CUICBAS, Universidad de Colima, Bernal Díaz del Castillo 340, Colima, Colima (Mexico); Fernández, Francisco M., E-mail: fernande@quimica.unlp.edu.ar [INIFTA (UNLP, CCT La Plata-CONICET), División Química Teórica, Diag. 113 y 64 (S/N), Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina); Garcia, Javier [INIFTA (UNLP, CCT La Plata-CONICET), División Química Teórica, Diag. 113 y 64 (S/N), Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina); Gutierrez, German [Facultad de Ciencias, CUICBAS, Universidad de Colima, Bernal Díaz del Castillo 340, Colima, Colima (Mexico)

2014-04-15

105

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

106

The Parameterized Complexity of Some Fundamental Problems of Linear Codes and Integer Lattices  

E-print Network

The Parameterized Complexity of Some Fundamental Problems of Linear Codes and Integer Lattices and integer lattices is explored. Concerning codes, the main results are that Maximum Likelihood Decoding problem of determining, for an integer lattice L, given by a set of generators, and a positive integer k

107

Complex representations of the full linear group over a finite field  

Microsoft Academic Search

The properties of the system of irreducible complex representations of full linear groups are described, without making use of the characteristics of the representations. The description is given in terms involving the multiplication of irreducible representations, which was introduced by Green. Explicitly, the concept of prime and primary representations is introduced, theorems are proved on the unique decomposition into primary

D. K. Faddeev

1978-01-01

108

Almost Linear Complexity Methods for Delay-Doppler Channel Alexander Fish and Shamgar Gurevich  

E-print Network

provide a striking improvement over current methods in the presence of a substantial Doppler effect1 Almost Linear Complexity Methods for Delay-Doppler Channel Estimation Alexander Fish and Shamgar of delay-Doppler channel, i.e., a signal undergoes only delay and Doppler shifts, a widely used method

Sydney, University of

109

Infrared diode laser spectroscopy of O2—N2O van der Waals complex in the ?1 symmetric stretch region of N2O  

NASA Astrophysics Data System (ADS)

The rovibrational spectrum of O2—N2O van der Waals complex is measured in the ?1 symmetric stretch region of N2O monomer using a tunable diode laser spectrometer. The complex is generated by a slit-pulsed supersonic expansion with gas mixtures of O2, N2O, and He. Both a- and b-type transitions are observed. The effective Hamiltonian for an open-shell complex consisting of a diatomic molecule in a 3? electronic state and a closed-shell partner is used to analyze the observed spectrum. Molecular constants in the vibrationally excited state are determined accurately. The band-origin of the spectrum is determined to be 1284.7504(25) cm?1, red-shifted from that of the N2O monomer by ~ 0.1529 cm?1.

Li, Song; Zheng, Rui; Duan, Chuan-Xi

2014-12-01

110

New Symmetrical and Unsymmetrical Nickel-Dithiolene Complexes Useful as Near-IR Dyes and Precursors of Sulfur-Rich Donors  

Microsoft Academic Search

Novel symmetrical and unsymmetrical nickel dithiolene complexes based on a new ligand R2timdt (the -1 charged 1,3-dialkylimidazolidine-2,4,S-trithione) and dmit or mnt (dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate; mnt = maleonitriledithiolate) useful as NIR-dyes and electrochromic materials in the 880-1400 nm region arc described here. The R2 timdt ligand, where N-electron donor atoms of the imidazoline ring are forced into co-planarity with the dithiolene

Paola Deplano; Maria Laura Mercuri; Gloria Pintus; Emanuele F. Trogu

2001-01-01

111

Synthesis, spectral characterization, DNA binding ability and antibacterial screening of copper(II) complexes of symmetrical NOON tetradentate Schiff bases bearing different bridges  

NASA Astrophysics Data System (ADS)

A novel series of four copper(II) complexes were synthesized by thermal reaction of copper acetate salt with symmetrical tetradentate Schiff bases, N,N'bis(o-vanillin)4,5-dimethyl-l,2-phenylenediamine (H2L1), N,N'bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H2L2), N,N'bis(o-vanillin)4,5-dichloro-1,2-phenylenediamine (H2L3) and N,N'bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H2L4), respectively. All the new synthesized complexes were characterized by using of microanalysis, FT-IR, UV-Vis, magnetic measurements, ESR, and conductance measurements, respectively. The data revealed that all the Schiff bases (H2L1-4) coordinate in their deprotonated forms and behave as tetradentate NOON coordinated ligands. Moreover, their copper(II) complexes have square planar geometry with general formula [CuL1-4]. The binding of the complexes with calf thymus DNA (CT-DNA) was investigated by UV-Vis spectrophotometry, fluorescence quenching and viscosity measurements. The results indicated that the complexes bind to CT-DNA through an intercalative mode. From the biological activity view, the copper(II) complexes and their parent ligands were screened for their in vitro antibacterial activity against the bacterial species Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosai by well diffusion method. The complexes showed an increased activity in comparison to some standard drugs.

Bahaffi, Saleh O.; Abdel Aziz, Ayman A.; El-Naggar, Maher M.

2012-08-01

112

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

113

Bayesian Model Selection in Complex Linear Systems, as Illustrated in Genetic Association Studies  

PubMed Central

Summary Motivated by examples from genetic association studies, this paper considers the model selection problem in a general complex linear model system and in a Bayesian framework. We discuss formulating model selection problems and incorporating context-dependent a priori information through different levels of prior specifications. We also derive analytic Bayes factors and their approximations to facilitate model selection and discuss their theoretical and computational properties. We demonstrate our Bayesian approach based on an implemented Markov Chain Monte Carlo (MCMC) algorithm in simulations and a real data application of mapping tissue-specific eQTLs. Our novel results on Bayes factors provide a general framework to perform efficient model comparisons in complex linear model systems. PMID:24350677

Wen, Xiaoquan

2013-01-01

114

Finding Lower Bounds on the Complexity of Secret Sharing Schemes by Linear Programming  

Microsoft Academic Search

\\u000a Determining the optimal complexity of secret sharing schemes for every given access structure is a difficult and long-standing\\u000a open problem in cryptology. Lower bounds have been found by a combinatorial method that uses polymatroids. In this paper,\\u000a we point out that the best lower bound that can be obtained by this method can be determined by using linear programming,\\u000a and

Carles Padró; Leonor Vázquez

2010-01-01

115

The linear ubiquitin assembly complex (LUBAC) is essential for NLRP3 inflammasome activation  

PubMed Central

Linear ubiquitination is a newly discovered posttranslational modification that is currently restricted to a small number of known protein substrates. The linear ubiquitination assembly complex (LUBAC), consisting of HOIL-1L, HOIP, and Sharpin, has been reported to activate NF-?B–mediated transcription in response to receptor signaling by ligating linear ubiquitin chains to Nemo and Rip1. Despite recent advances, the detailed roles of LUBAC in immune cells remain elusive. We demonstrate a novel HOIL-1L function as an essential regulator of the activation of the NLRP3/ASC inflammasome in primary bone marrow–derived macrophages (BMDMs) independently of NF-?B activation. Mechanistically, HOIL-1L is required for assembly of the NLRP3/ASC inflammasome and the linear ubiquitination of ASC, which we identify as a novel LUBAC substrate. Consequently, we find that HOIL-1L?/? mice have reduced IL-1? secretion in response to in vivo NLRP3 stimulation and survive lethal challenge with LPS. Together, these data demonstrate that linear ubiquitination is required for NLRP3 inflammasome activation, defining the molecular events of NLRP3 inflammasome activation and expanding the role of LUBAC as an innate immune regulator. Furthermore, our observation is clinically relevant because patients lacking HOIL-1L expression suffer from pyogenic bacterial immunodeficiency, providing a potential new therapeutic target for enhancing inflammation in immunodeficient patients. PMID:24958845

Rodgers, Mary A.; Bowman, James W.; Fujita, Hiroaki; Orazio, Nicole; Shi, Mude; Liang, Qiming; Amatya, Rina; Kelly, Thomas J.; Iwai, Kazuhiro; Ting, Jenny

2014-01-01

116

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

117

Multi-index algorithm of identifying important nodes in complex networks based on linear discriminant analysis  

NASA Astrophysics Data System (ADS)

The evaluation of node importance has great significance to complex network, so it is important to seek and protect important nodes to ensure the security and stability of the entire network. At present, most evaluation algorithms of node importance adopt the single-index methods, which are incomplete and limited, and cannot fully reflect the complex situation of network. In this paper, after synthesizing multi-index factors of node importance, including eigenvector centrality, betweenness centrality, closeness centrality, degree centrality, mutual-information, etc., the authors are proposing a new multi-index evaluation algorithm of identifying important nodes in complex networks based on linear discriminant analysis (LDA). In order to verify the validity of this algorithm, a series of simulation experiments have been done. Through comprehensive analysis, the simulation results show that the new algorithm is more rational, effective, integral and accurate.

Hu, Fang; Liu, Yuhua

2015-02-01

118

Enantioselective Friedel-Crafts alkylation reactions catalyzed by a chiral nonracemic C2-symmetric 2,2'-bipyridyl copper(II) complex.  

PubMed

Enantioselective Friedel-Crafts alkylation reactions of a series of substituted indoles with methyl trifluoropyruvate, catalyzed by a chiral nonracemic C(2)-symmetric 2,2'-bipyridyl copper(II) triflate complex, are described. The corresponding 3,3,3-trifluoro-2-hydroxy-2-indole-3-yl-propionic acid methyl esters were formed in good yield and in high enantiomeric excess (up to 90%). This is the first report of the use of a chiral nonracemic 2,2'-bipyridyl ligand in catalytic and enantioselective Friedel-Crafts alkylation reactions. The structural characterization of a copper(II) chloride complex of the chiral 2,2'-bipyridyl ligand by X-ray crystallography is also presented. [reaction: see text] PMID:15727470

Lyle, Michael P A; Draper, Neil D; Wilson, Peter D

2005-03-01

119

Synthesis of two new linear trinuclear Cu(II) complexes: mechanism of magnetic coupling through hybrid B3LYP functional and CShM studies.  

PubMed

Two new Cu(II) linear trinuclear Schiff base complexes, [Cu3(L)2(CH3COO)2] (1) and [Cu3(L)2(CF3COO)2] (2), have been prepared using a symmetrical Schiff base ligand H2L [where H2L = N,N'-bis(2-hydroxyacetophenone)propylenediimine]. Both of the complexes have been characterized by elemental analyses, Fourier transform IR, UV/vis, and electron paramagnetic resonance spectroscopy. Single-crystal X-ray structures show that the adjacent Cu(II) ions are linked by double phenoxo bridges and a mu(2)-eta(1):eta(1) carboxylato bridge. In each complex, the central copper atom is located in an inversion center with distorted octahedral coordination geometry, while the terminal copper atoms have square-pyramidal geometry. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit a distinct antiferromagnetic interaction of J = -36.5 and -72.3 cm(-1) for 1 and 2, respectively. Density functional theory calculations (B3LYP functional) and continuous-shape measurement (CShM) studies have been performed on the trinuclear unit to provide a qualitative theoretical interpretation of the antiferromagnetic behavior shown by the complexes. PMID:18572912

Thakurta, Santarupa; Chakraborty, Joy; Rosair, Georgina; Tercero, Javier; El Fallah, M Salah; Garribba, Eugenio; Mitra, Samiran

2008-07-21

120

Linear complexity integral-equation based methods for large-scale electromagnetic analysis  

NASA Astrophysics Data System (ADS)

In general, to solve problems with N parameters, the optimal computational complexity is linear complexity O( N). However, for most computational electromagnetic methods, the complexity is higher than O(N). In this work, we introduced and further developed the H - and H2 -matrix based mathematical framework to break the computational barrier of existing integral-equation (IE)-based methods for large-scale electromagnetic analysis. Our significant contributions include the first-time dense matrix inversion and LU factorization of O(N) complexity for large-scale 3-D circuit extraction and a fast direct integral equation solver that outperforms existing direct solvers for large-scale electrodynamic analysis having millions of unknowns and ˜100 wavelengths. The major contributions of this work are: (1) Direct Matrix Solution of Linear Complexity for 3-D Integrated Circuit (IC) and Package Extraction • O(N) complexity dense matrix inversion and LU factorization algorithms and their applications to capacitance extraction and impedance extraction of large-scale 3-D circuits • O(N) direct matrix solution of highly irregular matrices consisting of both dense and sparse matrix blocks arising from full-wave analysis of general 3-D circuits with lossy conductors in multiple dielectrics. (2) Fast H - and H2 -Based IE Solvers for Large-Scale Electrodynamic Analysis • theoretical proof on the error bounded low-rank representation of electrodynamic integral operators • fast H2 -based iterative solver with O(N) computational cost and controlled accuracy from small to tens of wavelengths • fast H -based direct solver with computational cost minimized based on accuracy • Findings on how to reduce the complexity of H - and H2 -based methods for electrodynamic analysis, which are also applicable to many other fast IE solvers. (3) Fast Algorithms for Accelerating H - and H2 -Based Iterative and Direct Solvers • Optimal H -based representation and its applications from circuits to electrically large problems • Optimal H2 -based representation for dense matrices arising from IE-based analysis • Iterative as well as direct solvers significantly accelerated by optimal H - and H2 -based representations. (4) Advanced Mathematical Computing • The construction of a simple H2 -representation with Csp = 1 • Linear-time matrix-matrix multiplication with controlled accuracy. The proposed methods have successfully solved large-scale electromagnetic scattering problems having 100 wavelengths and integrated circuit problems involving millions of unknowns in fast CPU time, modest memory consumption, and without sacrificing accuracy. Comparisons with state-of-the-art solvers have demonstrated the clear advantages of the proposed methods. The proposed methods have important applications in a wide range of areas such as electromagnetics, optics, acoustics, plasmonics, etc.

Chai, Wenwen

121

SHARPIN forms a linear ubiquitin ligase complex regulating NF-?B activity and apoptosis  

PubMed Central

SHARPIN is a ubiquitin-binding and ubiquitin-like domain-containing protein which, when mutated in mice, results in immune system disorders and multiorgan inflammation1,2. Here we report that SHARPIN functions as a novel component of the Linear Ubiquitin Chain Assembly Complex (LUBAC) and that the absence of SHARPIN causes disregulation of NF-?B and apoptotic signalling pathways, explaining the severe phenotypes displayed by chronic proliferative dermatitis in SHARPIN deficient mice. Upon binding to the LUBAC subunit HOIP, SHARPIN stimulates the formation of linear ubiquitin chains in vitro and in vivo. Co-expression of SHARPIN and HOIP promotes linear ubiquitylation of NEMO, an adaptor of the I?B kinases (IKKs) and subsequent activation of NF-?B signalling, while SHARPIN deficiency in mice causes an impaired activation of the IKK complex and NF-?B in B cells, macrophages, and mouse embryonic fibroblasts (MEFs). This effect is further enhanced upon concurrent downregulation of HOIL-1L, another HOIP-binding component of LUBAC. In addition, SHARPIN deficiency leads to rapid cell death upon TNF? stimulation via FADD- and Caspase-8-dependent pathways. SHARPIN thus activates NF-?B and inhibits apoptosis via distinct pathways in vivo. PMID:21455181

Ikeda, Fumiyo; Deribe, Yonathan Lissanu; Skånland, Sigrid S.; Stieglitz, Benjamin; Grabbe, Caroline; Franz-Wachtel, Mirita; van Wijk, Sjoerd J. L.; Goswami, Panchali; Nagy, Vanja; Terzic, Janos; Tokunaga, Fuminori; Androulidaki, Ariadne; Nakagawa, Tomoko; Pasparakis, Manolis; Iwai, Kazuhiro; Sundberg, John P.; Schaefer, Liliana; Rittinger, Katrin; Macek, Boris; Dikic, Ivan

2011-01-01

122

Gliotoxin Suppresses NF-?B Activation by Selectively Inhibiting Linear Ubiquitin Chain Assembly Complex (LUBAC).  

PubMed

A linear ubiquitin chain, which consists of ubiquitin molecules linked via their N- and C-termini, is formed by a linear ubiquitin chain assembly complex (LUBAC) composed of HOIP, HOIL-1L, and SHARPIN, and conjugation of a linear ubiquitin chain on the NF-?B essential modulator (NEMO) is deeply involved in NF-?B activation induced by various signals. Since abnormal activation of NF-?B is associated with inflammatory disease and malignancy, we searched for an inhibitor of LUBAC by high-throughput screening (HTS) with a Tb(3+)-fluorescein FRET system. As a result, we found that the fungal metabolite gliotoxin inhibits LUBAC selectively by binding to the RING-IBR-RING domain of HOIP, the catalytic center of LUBAC. Gliotoxin has been well-known as an inhibitor of NF-?B activation, though its action mechanism has remained elusive. Here, we show that gliotoxin inhibits signal-induced NF-?B activation by selectively inhibiting LUBAC-mediated linear ubiquitin chain formation. PMID:25494483

Sakamoto, Hiroki; Egashira, Shinichiro; Saito, Nae; Kirisako, Takayoshi; Miller, Simon; Sasaki, Yoshiteru; Matsumoto, Tadahiko; Shimonishi, Manabu; Komatsu, Toru; Terai, Takuya; Ueno, Tasuku; Hanaoka, Kenjiro; Kojima, Hirotatsu; Okabe, Takayoshi; Wakatsuki, Soichi; Iwai, Kazuhiro; Nagano, Tetsuo

2015-03-20

123

Metal-metal interactions in linear tri-, penta-, hepta-, and nona-nuclear ruthenium string complexes.  

PubMed

Density functional theory (DFT) methodology was used to examine the structural properties of linear metal string complexes: [Ru(3)(dpa)(4)X(2)] (X = Cl(-), CN(-), NCS(-), dpa = dipyridylamine(-)), [Ru(5)(tpda)(4)Cl(2)], and hypothetical, not yet synthesized complexes [Ru(7)(tpta)(4)Cl(2)] and [Ru(9)(ppta)(4)Cl(2)] (tpda = tri-?-pyridyldiamine(2-), tpta = tetra-?-pyridyltriamine(3-), ppta = penta-?-pyridyltetraamine(4-)). Our specific focus was on the two longest structures and on comparison of the string complexes and unsupported ruthenium backboned chain complexes, which have weaker ruthenium-ruthenium interactions. The electronic structures were studied with the aid of visualized frontier molecular orbitals, and Bader's quantum theory of atoms in molecules (QTAIM) was used to study the interactions between ruthenium atoms. The electron density was found to be highest and distributed most evenly between the ruthenium atoms in the hypothetical [Ru(7)(tpta)(4)Cl(2)] and [Ru(9)(ppta)(4)Cl(2)] string complexes. PMID:21870194

Niskanen, Mika; Hirva, Pipsa; Haukka, Matti

2012-05-01

124

{PT}-symmetric optical superlattices  

NASA Astrophysics Data System (ADS)

The spectral and localization properties of {PT}-symmetric optical superlattices, either infinitely extended or truncated at one side, are theoretically investigated, and the criteria that ensure a real energy spectrum are derived. The analysis is applied to the case of superlattices describing a complex ( {PT}-symmetric) extension of the Harper Hamiltonian in the rational case.

Longhi, Stefano

2014-04-01

125

A complex linear least-squares method to derive relative and absolute orientations of seismic sensors  

NASA Astrophysics Data System (ADS)

Determining the relative 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 or ocean bottom seismometers deployed at the seafloor. To solve this problem we propose a new inversion method based on a complex linear algebra approach. Relative orientation angles are retrieved by minimizing, in a least-squares sense, the l2-norm between the complex traces (hodograms) of adjacent pairs of sensors. This methodology can be applied without restrictions only if the wavefield recorded by each pair of sensors is very similar. In most cases, it is possible to satisfy this condition by low-pass filtering the recorded waveforms. The main advantage of our methodology is that, in the complex domain, the relative orientations of seismic sensors can be viewed as a linear inverse problem, which ensures that the preferred solution corresponds to the global minimum of a misfit function. It is also possible to use simultaneously more than one independent data set (other seismic events) to better constrain the solution of the inverse problem. Furthermore, by a computational point of view, our method results faster than the relative orientation methods based on waveform cross-correlation. After several tests on synthetic data sets we applied successfully our methodology to different types of real data. These applications include the alignment of borehole sensors relative to a Vertical Seismic Profiling (VSP) acquisition and the orientation of Ocean Bottom Seismometers (OBS) relative to a neighbouring land station of known orientation. Using land stations, the absolute orientation of OBS can be retrieved. Finally, as a last application, we checked the correct orientation for land stations of a seismological array in Germany.

Grigoli, Francesco; Cesca, Simone; Dahm, Torsten; Krieger, Lars

2012-03-01

126

Metallogels self-assembled from linear rod-like platinum complexes: influence of the linkage.  

PubMed

Two linear rod-like platinum complexes, which only differed in the linkage, were prepared. They both self-assemble into metallogels in nonpolar solvents; however, a very big contrast was observed. Unexpectedly, a much weaker gel was acquired upon replacing the ester linkage by an amide group. The intermolecular hydrogen bonding offered by the amide motif leads to a different stacking fashion and mechanism. The results demonstrated herein contribute to the rational design of metallogels as well as other functional supramolecular materials. PMID:25644237

Chen, Mingming; Wei, Chengsha; Wu, Xibo; Khan, Majid; Huang, Ningdong; Zhang, Guobin; Li, Liangbin

2015-03-01

127

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

128

Linear Superposition and Prediction of Bacterial Promoter Activity Dynamics in Complex Conditions  

PubMed Central

Bacteria often face complex environments. We asked how gene expression in complex conditions relates to expression in simpler conditions. To address this, we obtained accurate promoter activity dynamical measurements on 94 genes in E. coli in environments made up of all possible combinations of four nutrients and stresses. We find that the dynamics across conditions is well described by two principal component curves specific to each promoter. As a result, the promoter activity dynamics in a combination of conditions is a weighted average of the dynamics in each condition alone. The weights tend to sum up to approximately one. This weighted-average property, called linear superposition, allows predicting the promoter activity dynamics in a combination of conditions based on measurements of pairs of conditions. If these findings apply more generally, they can vastly reduce the number of experiments needed to understand how E. coli responds to the combinatorially huge space of possible environments. PMID:24809350

Rothschild, Daphna; Dekel, Erez; Hausser, Jean; Bren, Anat; Aidelberg, Guy; Szekely, Pablo; Alon, Uri

2014-01-01

129

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

130

Stability of localized modes in PT-symmetric nonlinear potentials  

E-print Network

We report on detailed investigation of the stability of localized modes in the nonlinear Schrodinger equations with a nonlinear parity-time (alias PT) symmetric potential. We are particularly focusing on the case where the spatially-dependent nonlinearity is purely imaginary. We compute the Evans function of the linear operator determining the linear stability of localized modes. Results of the Evans function analysis predict that for sufficiently small dissipation localized modes become stable when the propagation constant exceeds certain threshold value. This is the case for periodic and $\\tanh$-shaped complex potentials where the modes having widths comparable with or smaller than the characteristic width of the complex potential are stable, while broad modes are unstable. In contrast, in complex potentials that change linearly with transverse coordinate all modes are stable, what suggests that the relation between width of the modes and spatial size of the complex potential define the stability in the gen...

Zezyulin, D A; Konotop, V V

2011-01-01

131

Stable 2D localized modes in anisotropic media with harmonic and PT -symmetric potentials  

NASA Astrophysics Data System (ADS)

The analytical spatial localized mode solutions of a two-dimensional nonlinear Schrödinger equation with constant diffraction and nonlinearity in PT -symmetric potential are obtained, and the linear stability of these solutions is discussed. Then, the analytical spatial localized mode solutions in anisotropic media with harmonic and PT -symmetric potentials are also derived based on the relation between two nonlinear Schrödinger equations with variable and constant diffraction and nonlinearity. At last, the diffraction management of spatial localized modes in PT -symmetric complex potentials is investigated.

Chen, Yi-Xiang

2015-05-01

132

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

133

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

134

Waste management under multiple complexities: Inexact piecewise-linearization-based fuzzy flexible programming  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Inexact piecewise-linearization-based fuzzy flexible programming is proposed. Black-Right-Pointing-Pointer It's the first application to waste management under multiple complexities. Black-Right-Pointing-Pointer It tackles nonlinear economies-of-scale effects in interval-parameter constraints. Black-Right-Pointing-Pointer It estimates costs more accurately than the linear-regression-based model. Black-Right-Pointing-Pointer Uncertainties are decreased and more satisfactory interval solutions are obtained. - Abstract: To tackle nonlinear economies-of-scale (EOS) effects in interval-parameter constraints for a representative waste management problem, an inexact piecewise-linearization-based fuzzy flexible programming (IPFP) model is developed. In IPFP, interval parameters for waste amounts and transportation/operation costs can be quantified; aspiration levels for net system costs, as well as tolerance intervals for both capacities of waste treatment facilities and waste generation rates can be reflected; and the nonlinear EOS effects transformed from objective function to constraints can be approximated. An interactive algorithm is proposed for solving the IPFP model, which in nature is an interval-parameter mixed-integer quadratically constrained programming model. To demonstrate the IPFP's advantages, two alternative models are developed to compare their performances. One is a conventional linear-regression-based inexact fuzzy programming model (IPFP2) and the other is an IPFP model with all right-hand-sides of fussy constraints being the corresponding interval numbers (IPFP3). The comparison results between IPFP and IPFP2 indicate that the optimized waste amounts would have the similar patterns in both models. However, when dealing with EOS effects in constraints, the IPFP2 may underestimate the net system costs while the IPFP can estimate the costs more accurately. The comparison results between IPFP and IPFP3 indicate that their solutions would be significantly different. The decreased system uncertainties in IPFP's solutions demonstrate its effectiveness for providing more satisfactory interval solutions than IPFP3. Following its first application to waste management, the IPFP can be potentially applied to other environmental problems under multiple complexities.

Sun Wei [Faculty of Engineering and Applied Science, University of Regina, Regina, Saskatchewan, S4S 0A2 (Canada); Huang, Guo H., E-mail: huang@iseis.org [Institute for Energy, Environment and Sustainability Research, UR-NCEPU, North China Electric Power University, Beijing 102206 (China); Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan, S4S 0A2 (Canada); Lv Ying; Li Gongchen [Faculty of Engineering and Applied Science, University of Regina, Regina, Saskatchewan, S4S 0A2 (Canada)

2012-06-15

135

Exploring complexity of large update interior-point methods for P*(kappa) linear complementarity problem based on Kernel function  

Microsoft Academic Search

Interior-point methods not only are the most effective methods in practice but also have polynomial-time complexity. The large update interior-point methods perform in practice much better than the small update methods which have the best known theoretical complexity. In this paper, motivated by the complexity results for linear optimization based on kernel functions, we extend a generic primal-dual interior-point algorithm

Keyvan Amini; M. Reza Peyghami

2009-01-01

136

Preparation, linear and NLO properties of DNA-CTMA-SBE complexes  

NASA Astrophysics Data System (ADS)

Synthesis of deoxyribonucleic acid (DNA) - was cetyltrimethylammonium (CTMA) - sea buckthorn extract (SBE) at different concentrations is decribed. The complexes were processed into good optical quality thin films by spin coating on different substrates such as: glass, silica and ITO covered glass substrates. SBE contains many bioactive substances that can be used in the treatment of several diseases, such as cardiovascular disease, cancer, and acute mountain sickness. The obtained thin films were characterized for their spectroscopic, fluorescent, linear and nonlinear optical properties as function of SBE concentration. The third-order nonlinear optical (NLO) properties of thin films were determined by the optical third-harmonic generation technique at 1 064.2 nm fundamental wavelength.

Manea, Ana-Maria; Rau, Ileana; Kajzar, Francois; Meghea, Aurelia

2013-10-01

137

Simple scheme for universal linear-optics quantum computing with constant experimental complexity using fiber loops  

NASA Astrophysics Data System (ADS)

Recently, Motes, Gilchrist, Dowling, and Rohde [Phys. Rev. Lett. 113, 120501 (2014)., 10.1103/PhysRevLett.113.120501] presented a scheme for photonic boson sampling using a fiber-loop architecture. Here we show that the same architecture can be modified to implement full, universal linear-optics quantum computing, in various incarnations. The scheme employs two embedded fiber loops, a single push-button photon source, three dynamically controlled beamsplitters, and a single time-resolved photodetector. The architecture has only a single point of interference, and thus may be significantly easier to align than other schemes. The experimental complexity of the scheme is constant, irrespective of the size of the computation, limited only by fiber lengths and their respective loss rates.

Rohde, Peter P.

2015-01-01

138

Exponential synchronization of complex networks of linear systems and nonlinear oscillators: a unified analysis.  

PubMed

A unified approach to the analysis of synchronization for complex dynamical networks, i.e., networks of partial-state coupled linear systems and networks of full-state coupled nonlinear oscillators, is introduced. It is shown that the developed analysis can be used to describe the difference between the state of each node and the weighted sum of the states of those nodes playing the role of leaders in the networks, thus making it feasible to consider the error dynamics for the whole network system. Different from the other various methods given in the existing literature, the analysis employed in this paper is demonstrated successfully in not only providing the consistent convergence analysis with much simpler form, but also explicitly specifying the convergence rate. PMID:25720007

Qin, Jiahu; Gao, Huijun; Zheng, Wei Xing

2015-03-01

139

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

140

Linear-algebraic bath transformation for simulating complex open quantum systems  

NASA Astrophysics Data System (ADS)

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; Mostame, Sarah; Fujita, Takatoshi; Yung, Man-Hong; Aspuru-Guzik, Alán

2014-12-01

141

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

NASA Astrophysics Data System (ADS)

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 (H2, HD, CO, O2, and CO2) and nonlinear (H2O and NH3) molecules in ultracold collisions with He and report the corresponding complex scattering lengths. It has been found that the ratio of the imaginary component ? to the real component ? of the scattering length generally increases with decreasing rotational constant for linear molecules. With the exception of CO, ? becomes significantly smaller than ? as the energy gap for rotational transitions increases. In all cases, ? decreases with rotational energy gap for relatively large rotational excitation, allowing for convenient fits to an exponential energy gap formula. Excited rotational levels of H2 and HD appear to be collisionally stable due to the very low values of ?/?. Rotationally excited H2O also appears to be a viable candidate for He buffer gas cooling due to relatively small values of ?.

Yang, Benhui; Forrey, R. C.; Stancil, P. C.; Balakrishnan, N.

2010-11-01

142

Synthesis and characterization of a series of transition metal complexes with a new symmetrical polyoxaaza macroacyclic Schiff base ligand: X-ray crystal structure of cobalt(II) and nickel(II) complexes and their antibacterial properties  

NASA Astrophysics Data System (ADS)

A new symmetrical [N4O2] hexadentate Schiff base ligand, (E)-N-(pyridin-2-ylmethylene)-2-(3-(2-((E)-pyridin-2-lmethyleneamino)phenoxy)naphthalen-2-yloxy)benzenamine, abbreviated to L, and its complexes of Ni(II), Cu(II), Zn(II), Co(II), Cd(II) and Mn(II) have been synthesized in the presence of metal ions. The complexes were structurally characterized by elemental analyses, IR, UV-Vis, NMR and molar conductivity. The crystal structures of two complexes, [NiL(ONO2)2]·2H2O and [CoLCl2]CH3OH·0.5H2O, have been determined by a single crystal X-ray diffraction study. In these complexes, the ligand is coordinated in a neutral form via pyridine and azomethine nitrogen atoms. The metal ions complete their six coordination with two coordinated nitrate or chloride ions, forming a distorted octahedral geometry. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Enterococcus faecalis, Bacillus cereus and Staphylococcus epid and also against the three Gram-negative bacteria: Citrobacter freundii, Enterobacter aerogenes and Salmonella typhi. The activity data show that the complexes are more potent antibacterials than the parent Schiff base.

Keypour, Hassan; Shayesteh, Maryam; Rezaeivala, Majid; Chalabian, Firoozeh; Valencia, Laura

2013-01-01

143

Turning symmetric an asymmetric hydrogen bond with the inclusion of nuclear quantum effects: The case of the [CN...H...NC]- complex  

NASA Astrophysics Data System (ADS)

Nuclear quantum effects (NQE) on the geometry, energy, and electronic structure of the [{CN}\\cdot {L} \\cdot {NC}]- complex (L = H, D, T) are investigated with the recently developed APMO/MP2 code. This code implements the nuclear molecular orbital approach (NMO) at the Hartree-Fock (HF) and MP2 levels of theory for electrons and quantum nuclei. In a first study, we examined the H/D/T isotope effects on the geometry and electronic structure of the CNH molecule at NMO/HF and NMO/MP2 levels of theory. We found that when increasing the hydrogen nuclear mass there is a reduction of the R_{{N-H}} bond distance and an increase of the electronic population on the hydrogen atom. Our calculated bond distances are in good agreement with experimental and other theoretical results. In a second investigation, we explored the hydrogen NQE on the geometry of [CNHNC] ^- complex at the NMO/HF and NMO/MP2 levels of theory. We discovered that while a NMO/HF calculation presented an asymmetric hydrogen bond, the NMO/MP2 calculation revealed a symmetric H-bond. We also examined the H/D/T isotope effects on the geometry and stabilization energy of the [CNHNC] ^- complex. We noted that gradual increases in hydrogen mass led to reductions of the R_{{NN}} distance and destabilization of the hydrogen bond (H-bond). A discussion of these results is given in terms of the hydrogen nuclear delocalization effects on the electronic structure and energy components. To the best of our knowledge, this is the first ab initio NMO study that reveals the importance of including nuclear quantum effects in conventional electronic structure calculations for an enhanced description of strong-low-barrier H-bonded systems.

Moreno, Diego V.; González, Sergio A.; Reyes, Andrés

2011-01-01

144

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

145

Dual emission and excited-state mixed-valence in a quasi-symmetric dinuclear Ru-Ru complex.  

PubMed

The synthesis and characterization of the new dinuclear dipeptide [(EtOOC-tpy)Ru(tpy-NHCO-tpy)Ru(tpy-NHCOCH3)](4+) 3(4+) of the bis(terpyridine)ruthenium amino acid [(HOOC-tpy)Ru(tpy-NH2)](2+) 1(2+) are described, and the properties of the dipeptide are compared to those of the mononuclear complex [(EtOOC-tpy)Ru(tpy-NHCOCH3)](2+) 4(2+) carrying the same functional groups. 3(4+) is designed to serve a high electronic similarity of the two ruthenium sites despite the intrinsic asymmetry arising from the amide bridge. This is confirmed via UV-vis absorption and NMR spectroscopy as well as cyclic voltammetry. 4(2+) and 3(4+) are emissive at room temperature, as expected. Moreover, 3(4+) exhibits dual emission from two different triplet states with different energies and lifetimes at room temperature. This is ascribed to the presence of a unique thermal equilibrium between coexisting [Ru(II)(tpy-NHCO-tpy(·-))Ru(III)] and [Ru(III)(tpy-NHCO-tpy(·-))Ru(II)] states leading to an unprecedented excited-state Ru(II)Ru(III) mixed-valent system via the radical anion bridge tpy-NHCO-tpy(·-). The mixed-valent cation 3(5+), on the other hand, shows no measurable interaction of the Ru(II)Ru(III) centers via the neutral bridge tpy-NHCO-tpy (Robin-Day class I). Reduction of 3(4+) to the radical cation 3(3+) by decamethylcobaltocene is bridge-centered as evidenced by rapid-freeze electron paramagnetic resonance spectroscopy. Interestingly, all attempts to observe 3(3+) via NMR and UV-vis absorption spectroscopy only led to the detection of the diamagnetic complex 3-H(3+) in which the bridging amide is deprotonated. Hence 3-H(3+) (and 4-H(+)) appear to reduce protons to dihydrogen. The ease of single and double deprotonation of 4(2+) and 3(4+) to 4-H(+), 3-H(3+), and 3-2H(2+) was demonstrated using a strong base and was studied using NMR and UV-vis absorption spectroscopies. The equilibrating excited triplet states of 3(4+) are reductively quenched by N,N-dimethylaniline assisted by hydrogen bonding to the bridging amide. PMID:25412276

Kreitner, Christoph; Grabolle, Markus; Resch-Genger, Ute; Heinze, Katja

2014-12-15

146

T-Matrix Modeling of Linear Depolarization by Morphologically Complex Soot and Soot-Containing Aerosols  

NASA Technical Reports Server (NTRS)

We use state-of-the-art public-domain Fortran codes based on the T-matrix method to calculate orientation and ensemble averaged scattering matrix elements for a variety of morphologically complex black carbon (BC) and BC-containing aerosol particles, with a special emphasis on the linear depolarization ratio (LDR). We explain theoretically the quasi-Rayleigh LDR peak at side-scattering angles typical of low-density soot fractals and conclude that the measurement of this feature enables one to evaluate the compactness state of BC clusters and trace the evolution of low-density fluffy fractals into densely packed aggregates. We show that small backscattering LDRs measured with groundbased, airborne, and spaceborne lidars for fresh smoke generally agree with the values predicted theoretically for fluffy BC fractals and densely packed near-spheroidal BC aggregates. To reproduce higher lidar LDRs observed for aged smoke, one needs alternative particle models such as shape mixtures of BC spheroids or cylinders.

Mishchenko, Michael I.; Liu, Li; Mackowski, Daniel W.

2013-01-01

147

T-matrix modeling of linear depolarization by morphologically complex soot and soot-containing aerosols  

NASA Astrophysics Data System (ADS)

We use state-of-the-art public-domain Fortran codes based on the T-matrix method to calculate orientation and ensemble averaged scattering matrix elements for a variety of morphologically complex black carbon (BC) and BC-containing aerosol particles, with a special emphasis on the linear depolarization ratio (LDR). We explain theoretically the quasi-Rayleigh LDR peak at side-scattering angles typical of low-density soot fractals and conclude that the measurement of this feature enables one to evaluate the compactness state of BC clusters and trace the evolution of low-density fluffy fractals into densely packed aggregates. We show that small backscattering LDRs measured with ground-based, airborne, and spaceborne lidars for fresh smoke generally agree with the values predicted theoretically for fluffy BC fractals and densely packed near-spheroidal BC aggregates. To reproduce higher lidar LDRs observed for aged smoke, one needs alternative particle models such as shape mixtures of BC spheroids or cylinders.

Mishchenko, Michael I.; Liu, Li; Mackowski, Daniel W.

2013-07-01

148

Complexity analysis of interior-point methods for linear optimization based on some conditions on kernel function  

Microsoft Academic Search

Interior point methods have shown their powers in solving linear optimization problems and large classes of other optimization problems. However, at present there is still a gap between the practical behavior of these algorithms and their theoretical worst case complexity. The so-called large update interior point methods perform in practice much better than the small update methods which have the

K. Amini; M. R. Peyghami

2006-01-01

149

On the holomorphic rigidity of linear operators on complex Banach spaces  

E-print Network

B for a linear operator L: E ! F with kLk = 1. Such linear operators L we also call rigid. The paper is organized study linear operators L: E ! F with kLk = 1 and call L rigid if the induced map between the open unit

Arazy, Jonathan

150

Light propagation in periodically modulated complex waveguides  

NASA Astrophysics Data System (ADS)

Light propagation in optical waveguides with periodically modulated index of refraction and alternating gain and loss are investigated for linear and nonlinear systems. Based on a multiscale perturbation analysis, it is shown that for many non-parity-time- (PT -) symmetric waveguides, their linear spectrum is partially complex; thus light exponentially grows or decays upon propagation, and this growth or decay is not altered by nonlinearity. However, several classes of non-PT -symmetric waveguides are also identified to possess all-real linear spectrum. For PT -symmetric waveguides, phase transition is predicted analytically. In the nonlinear regime longitudinally periodic and transversely quasilocalized modes are found for PT -symmetric waveguides both above and below phase transition. These nonlinear modes are stable under evolution and can develop from initially weak initial conditions.

Nixon, Sean; Yang, Jianke

2015-03-01

151

Lanthanide complexes of tritopic bis(hydrazone) ligands: single-molecule magnet behavior in a linear Dy(III)3 complex.  

PubMed

Tritopic pyridinebis(hydrazone)-based ligands typically produce square M(9) [3 × 3] grid complexes with first-row transition-metal ions (e.g., M = Mn, Fe, Co, Cu, Zn), but with larger lanthanide ions, such coordination motifs are not produced, and instead linear trinuclear complexes appear to be a preferred option. The reaction of 2pomp [derived from pyridine-2,6-bis(hydrazone) and 2-acetylpyridine] with La(III), Gd(III), and Dy(III) salts produces helical linear trinuclear [Ln(3)(2pomp)(2)]-based complexes, where each metal ion occupies one of the three tridentate ligand pockets. Two ligands encompass the three metal ions, and internal connections between metal ions occur through ?-O(hydrazone) bridges. Coligands include benzoate, nitrate, and N,N-dimethylformamide. The linear Dy(III)(3) complex exhibits single-molecule magnet behavior, demonstrated through alternating-current susceptibility measurements. Slow thermal magnetic relaxation was detected in an external field of 1800 Oe, where quantum-tunneling effects were suppressed (U(eff) = 14 K). PMID:22191543

Anwar, Muhammad U; Tandon, Santokh S; Dawe, Louise N; Habib, Fatemah; Murugesu, Muralee; Thompson, Laurence K

2012-01-16

152

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

153

Micelle formation in a dilute solution of block copolymers with a polyelectrolyte block complexed with oppositely charged linear chains  

NASA Astrophysics Data System (ADS)

The theory of micelle formation in a dilute solution mixture of polyelectrolyte/neutral diblock copolymers and oppositely charged linear chains has been developed. The core of the micelles is formed by the hydrophobic monomer units of polyelectrolyte complexes between the oppositely charged polyions while the hydrophilic uncharged blocks of the block copolymers comprise the micellar corona. The process of the formation of polyelectrolyte complexes and micelles in the solution has been described as sets of association-dissociation reactions with certain chemical constants and the concentration distribution of micellar aggregates of a given composition has been calculated for various concentrations of linear chains and block copolymer macromolecules in the solution. It was shown that the micelles are formed by nearly fully neutralized block copolymers, so that the micellar charge is close to zero. The aggregation number of the micelles and their charge slightly depend on the concentration of the block copolymers as well as the linear chains in the solution. Micelles in the solution coexist with single block copolymer chain/linear polymer complexes of different composition.

Kramarenko, E. Yu.; Khokhlov, A. R.; Reineker, P.

2003-09-01

154

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

155

Linearly Compressed Pages: A Main Memory Compression Framework with Low Complexity and Low Latency  

E-print Network

>on: Linearly Compressed Pages (LCP): fixed-size cache line granularity compression Compression Linearly Compressed Pages (LCP): Key Idea LCP Overview Key Results.5 Compression Ra>o GeoMean Zero Page FPC LCP (BDI) LCP (BDI+FPC-fixed) MXT LZ

Mutlu, Onur

156

Smoothed analysis of condition numbers and complexity implications for linear programming  

Microsoft Academic Search

We perform a smoothed analysis of Renegar's condition number for linear programming by analyzing the distribution of the distance to ill-posedness of a linear program subject to a slight Gaussian perturbation. In particular, we show that for every n-by-d matrix ¯

John Dunagan; Daniel A. Spielman; Shang-Hua Teng

2011-01-01

157

Nonlinear symmetric stability of planetary atmospheres  

SciTech Connect

The energy-Casimir method is applied to the problem of symmetric stability in the context of a compressible, hydrostatic planetary atmosphere with a general equation of state. Linear stability criteria for symmetric disturbances to a zonally symmetric baroclinic flow are obtained. In the special case of a perfect gas the results of Stevens (1983) are recovered. Nonlinear stability conditions are also obtained that, in addition to implying linear stability, provide an upper bound on a certain positive-definite measure of disturbance amplitude.

Bowman, J.C. [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies; Shepherd, T.G. [Toronto Univ., ON (Canada). Dept. of Physics

1994-11-01

158

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

159

Charge-resonance excitations in symmetric molecules - Comparison of linear response DFT with CC3 for the excited states of a model dimer  

NASA Astrophysics Data System (ADS)

We present a study on the excited states of an ethylene dimer as to investigate the presence of and perturbation from low-lying charge-resonance states calculated by linear response density functional theory (DFT) using the B3LYP and CAM-B3LYP functionals. The calculations are compared to a reference CC3 calculation revealing a better description of the excited states by CAM-B3LYP than that of B3LYP. The ? parameter introduced by Peach et al. [M.J.G. Peach, P. Benfield, T. Helgaker, D.J. Tozer, J. Chem. Phys. 128 (2008) 044118] does not always reveal the problematic charge-resonance states obtained with B3LYP. The generality of the problem is addressed by taking pentacene as an example.

Kuhlman, Thomas S.; Mikkelsen, Kurt V.; Møller, Klaus B.; Sølling, Theis I.

2009-08-01

160

Linearly Compressed Pages: A Main Memory Compression Framework with Low Complexity and Low Latency  

E-print Network

call Linearly Compressed Pages (LCP). The key idea of LCP is that if all the cache lines within a page (Frequent Pattern Compression [2] and Base- Delta-Immediate Compression [6]) to fit the requirements of LCP

161

Lower bounds and complete problems in nondeterministic linear time and sublinear space complexity classes  

Microsoft Academic Search

Proving lower bounds remains the most difficult of tasks in computational\\u000acomplexity theory. In this paper, we show that whereas most natural NP-complete\\u000aproblems belong to NLIN (linear time on nondeterministic RAMs), some of them,\\u000atypically the planar versions of many NP-complete problems are recognized by\\u000anondeterministic RAMs in linear time and sublinear space. The main results of\\u000athis paper

Philippe Chapdelaine; Etienne Grandjean

2006-01-01

162

Transmission of linear regression patterns between time series: from relationship in time series to complex networks.  

PubMed

The linear regression parameters between two time series can be different under different lengths of observation period. If we study the whole period by the sliding window of a short period, the change of the linear regression parameters is a process of dynamic transmission over time. We tackle fundamental research that presents a simple and efficient computational scheme: a linear regression patterns transmission algorithm, which transforms linear regression patterns into directed and weighted networks. The linear regression patterns (nodes) are defined by the combination of intervals of the linear regression parameters and the results of the significance testing under different sizes of the sliding window. The transmissions between adjacent patterns are defined as edges, and the weights of the edges are the frequency of the transmissions. The major patterns, the distance, and the medium in the process of the transmission can be captured. The statistical results of weighted out-degree and betweenness centrality are mapped on timelines, which shows the features of the distribution of the results. Many measurements in different areas that involve two related time series variables could take advantage of this algorithm to characterize the dynamic relationships between the time series from a new perspective. PMID:25122353

Gao, Xiangyun; An, Haizhong; Fang, Wei; Huang, Xuan; Li, Huajiao; Zhong, Weiqiong; Ding, Yinghui

2014-07-01

163

Transmission of linear regression patterns between time series: From relationship in time series to complex networks  

NASA Astrophysics Data System (ADS)

The linear regression parameters between two time series can be different under different lengths of observation period. If we study the whole period by the sliding window of a short period, the change of the linear regression parameters is a process of dynamic transmission over time. We tackle fundamental research that presents a simple and efficient computational scheme: a linear regression patterns transmission algorithm, which transforms linear regression patterns into directed and weighted networks. The linear regression patterns (nodes) are defined by the combination of intervals of the linear regression parameters and the results of the significance testing under different sizes of the sliding window. The transmissions between adjacent patterns are defined as edges, and the weights of the edges are the frequency of the transmissions. The major patterns, the distance, and the medium in the process of the transmission can be captured. The statistical results of weighted out-degree and betweenness centrality are mapped on timelines, which shows the features of the distribution of the results. Many measurements in different areas that involve two related time series variables could take advantage of this algorithm to characterize the dynamic relationships between the time series from a new perspective.

Gao, Xiangyun; An, Haizhong; Fang, Wei; Huang, Xuan; Li, Huajiao; Zhong, Weiqiong; Ding, Yinghui

2014-07-01

164

Two dimensional symmetric correlation functions of the ? operator and two dimensional Fourier transforms: considering the line coupling for P and R lines of linear molecules.  

PubMed

The refinement of the Robert-Bonamy (RB) formalism by considering the line coupling for isotropic Raman Q lines of linear molecules developed in our previous study [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] has been extended to infrared P and R lines. In these calculations, the main task is to derive diagonal and off-diagonal matrix elements of the Liouville operator iS1 - S2 introduced in the formalism. When one considers the line coupling for isotropic Raman Q lines where their initial and final rotational quantum numbers are identical, the derivations of off-diagonal elements do not require extra correlation functions of the ? operator and their Fourier transforms except for those used in deriving diagonal elements. In contrast, the derivations for infrared P and R lines become more difficult because they require a lot of new correlation functions and their Fourier transforms. By introducing two dimensional correlation functions labeled by two tensor ranks and making variable changes to become even functions, the derivations only require the latters' two dimensional Fourier transforms evaluated at two modulation frequencies characterizing the averaged energy gap and the frequency detuning between the two coupled transitions. With the coordinate representation, it is easy to accurately derive these two dimensional correlation functions. Meanwhile, by using the sampling theory one is able to effectively evaluate their two dimensional Fourier transforms. Thus, the obstacles in considering the line coupling for P and R lines have been overcome. Numerical calculations have been carried out for the half-widths of both the isotropic Raman Q lines and the infrared P and R lines of C2H2 broadened by N2. In comparison with values derived from the RB formalism, new calculated values are significantly reduced and become closer to measurements. PMID:24628166

Ma, Q; Boulet, C; Tipping, R H

2014-03-14

165

Two Dimensional Symmetric Correlation Functions of the S Operator and Two Dimensional Fourier Transforms: Considering the Line Coupling for P and R Lines of Linear Molecules  

NASA Technical Reports Server (NTRS)

The refinement of the Robert-Bonamy (RB) formalism by considering the line coupling for isotropic Raman Q lines of linear molecules developed in our previous study [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] has been extended to infrared P and R lines. In these calculations, the main task is to derive diagonal and off-diagonal matrix elements of the Liouville operator iS1 - S2 introduced in the formalism. When one considers the line coupling for isotropic Raman Q lines where their initial and final rotational quantum numbers are identical, the derivations of off-diagonal elements do not require extra correlation functions of the ^S operator and their Fourier transforms except for those used in deriving diagonal elements. In contrast, the derivations for infrared P and R lines become more difficult because they require a lot of new correlation functions and their Fourier transforms. By introducing two dimensional correlation functions labeled by two tensor ranks and making variable changes to become even functions, the derivations only require the latters' two dimensional Fourier transforms evaluated at two modulation frequencies characterizing the averaged energy gap and the frequency detuning between the two coupled transitions. With the coordinate representation, it is easy to accurately derive these two dimensional correlation functions. Meanwhile, by using the sampling theory one is able to effectively evaluate their two dimensional Fourier transforms. Thus, the obstacles in considering the line coupling for P and R lines have been overcome. Numerical calculations have been carried out for the half-widths of both the isotropic Raman Q lines and the infrared P and R lines of C2H2 broadened by N2. In comparison with values derived from the RB formalism, new calculated values are significantly reduced and become closer to measurements.

Ma, Q.; Boulet, C.; Tipping, R. H.

2014-01-01

166

Modern Symmetric Cryptography methodologies and its applications  

E-print Network

Nowadays, using cryptographic systems play an effective role in security and safety technologies. One of the most applied kind of cryptography is Symmetric Cryptography and its applications. New aspects of symmetric Cryptography methodologies and applications has been presented by this paper. Security-based networks and some complex technologies such as RFID and parallel security settings has been intro-duced by using Symmetric Cryptography is the main base of discussion in this paper. Designing an unique protocol for Symmetric Cryptography in security networks elements is our focus. Reviewing benefits of using these methodologies has been pre-sented and discussed in this paper.

Malayeri, Amin Daneshmand

2009-01-01

167

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

168

Performance comparison of iteratively filtered and decoded MDD and PSAM systems with linear complexity  

Microsoft Academic Search

Joint channel estimation and decoding in a time-varying Rayleigh fading channel is considered. Knowing that the optimal design has an exponential complexity which hinders the practicability, a reduced complexity approach is proposed. This approach keeps the existing channel estimation and decoding schemes almost intact, while applying the turbo or iterative processing principle to enable information exchange between them. Thus the

Hsuan-Jung Su; Evaggelos Geraniotis

1999-01-01

169

Interpolation via symmetric exponential functions  

NASA Astrophysics Data System (ADS)

Complex valued functions on the Euclidean space Bbb Rn, symmetric or antisymmetric with respect to the permutation group Sn, are often dealt with in various branches of physics, such as quantum theory or theory of integrable systems. One often needs to approximate such functions with series consisting of various special functions which satisfy nice properties. Questions of uniform convergence of such approximations are crucial for applications. In this article a family of special functions called the symmetric exponential functions are used for such approximation and the uniform convergence of their sums is considered.

Bezubik, Agata; Pošta, Severin

2013-11-01

170

Estimation of Complex Generalized Linear Mixed Models for Measurement and Growth  

ERIC Educational Resources Information Center

Maximum likelihood (ML) estimation of generalized linear mixed models (GLMMs) is technically challenging because of the intractable likelihoods that involve high dimensional integrations over random effects. The problem is magnified when the random effects have a crossed design and thus the data cannot be reduced to small independent clusters. A…

Jeon, Minjeong

2012-01-01

171

Scaled Langevin equation for complex systems: New linear scaling relation for weight factor  

Microsoft Academic Search

A set of scaled Langevin equations is proposed to study a long time tail of correlation functions for two model systems (Type I and Type II). Each system is composed of elements which are grouped into clusters according to dynamical activations for external forces. The clusters in Type I are characterized by linear scaling rules in repetitive operations, whereas the

S. Fujita; S. S. Lee; J. Koyama

1997-01-01

172

Decidability and complexity for the verification of safety properties of reasonable linear hybrid automata  

Microsoft Academic Search

This paper identifies an industrially relevant class of linear hybrid automata (LHA) called reasonable LHA for which parametric verification of safety properties with exhaustive entry conditions can be done in polynomial time and time-bounded reachability with exhaustive entry conditions can be decided in nondeterministic polynomial time for non-parametric verification and in exponential time for parametric verification. Deciding whether an LHA

Werner Damm; Carsten Ihlemann; Viorica Sofronie-Stokkermans

2011-01-01

173

The Complexity of Large-scale Convex Programming under a Linear ...  

E-print Network

complexity bound in terms of its dependence on ? after properly incorporating the randomized ...... These problems arise from certain important applications, including compressed sensing and portfolio ..... Automation and Remote Control,.

2013-09-21

174

Prediction of partitioning between complex organic mixtures and water: application of polyparameter linear free energy relationships  

Microsoft Academic Search

Equilibrium partitioning between nonaqueous phase liquids (NAPLs) and water is a governing process for contaminants leaching from NAPLs. This study introduces a polyparameter linear free energy relationship (PP-LFER) approach as a more general tool to predict NAPL-water partitioning coefficients. The approach was evaluated using 441 experimental partitioning data from 30 references. Experimental fuel-water partitioning coefficients were generally well reproduced by

Satoshi Endo; Torsten C. Schmidt

2006-01-01

175

Action of the complex Monge-Ampère operator on piecewise-linear functions and exponential tropical varieties  

NASA Astrophysics Data System (ADS)

We consider exponential tropical varieties, which appear as analogues of algebraic tropical varieties when we pass from algebraic varieties to varieties given by zero sets of systems of exponential sums. We describe a construction of exponential tropical varieties arising from the action of the complex Monge-Ampère operator on piecewise-linear functions and show that every such variety can be obtained in this way. As an application, we deduce a criterion for the vanishing of the value of the mixed Monge-Ampère operator. This is an analogue and generalization of the criterion for the vanishing of the mixed volume of convex bodies.

Kazarnovskii, B. Ya

2014-10-01

176

A (Not Really) Complex Method for Finding Solutions to Linear Differential Equations. Modules and Monographs in Undergraduate Mathematics and Its Applications Project. UMAP Unit 497.  

ERIC Educational Resources Information Center

This module considers ordinary linear differential equations with constant coefficients. The "complex method" used to find solutions is discussed, with numerous examples. The unit includes both problem sets and an exam, with answers provided for both. (MP)

Uebelacker, James W.

177

Multi?linear strategies for (re)presenting the complexity of young people in research  

Microsoft Academic Search

Within the current climate of unpredictability and constant change, young people at school are faced with a multitude of choices and contradictory influences. In this article, I argue that (re)presentations of young people in youth research need to reflect the complexity and multiplicity of their lives and changing priorities, and I attempt to (re)present a small group of young people

Mary Elizabeth Ryan

2010-01-01

178

A new complexity result on multiobjective linear integer programming using short rational generating functions  

Microsoft Academic Search

This paper presents a new complexity result for solving multiobjective integer programming problems. We prove that encoding\\u000a the entire set of nondominated solutions of the problem in a short sum of rational functions is polynomially doable, when\\u000a the dimension of the decision space is fixed. This result extends a previous result presented in De Loera et al. (INFORMS\\u000a J. Comput. 21(1):39–48,

Víctor Blanco; Justo Puerto

179

Activation of H2 by a highly distorted Rh(II) complex with a new C3-symmetric tripodal tetraphosphine ligand.  

PubMed

Facile oxidation of a sterically encumbered Rh(I) complex generates a stable Rh(II) metalloradical species; the latter is able to activate H(2) under formation of the corresponding Rh(III) complex. PMID:20449260

Wassenaar, Jeroen; de Bruin, Bas; Siegler, Maxime A; Spek, Anthony L; Reek, Joost N H; van der Vlugt, Jarl Ivar

2010-02-28

180

Linear oxygen-sensing response from a rhenium complex induced by heavy atom: synthesis, characterization, photophysical study and sensing performance.  

PubMed

In this paper, we synthesized a Br-containing ligand of 2-(4-bromophenyl)-5-(pyridin-2-yl)-1,3,4-oxadiazole and its corresponding Re(I) complex. Their synthesis, characterization, single crystal structure, electronic transitions and photophysical property were presented and discussed in detail. This Re(I) complex was found to be a yellow emitter with slim ???* radiative decay contribution, and its emission was also found to be sensitive towards O2. By doping this Re(I) complex into a polymer matrix, the oxygen-sensing performance of the resulted composite nanofibers was also investigated. Owing to the porous structure of the supporting matrix, the optimal sample gave the highest sensitivity of 3.91 with short response time of only 9 s. In addition, the linearity of the Stern-Volmer plots was greatly improved due to the highly pure emissive center triggered by heavy-atom turbulence effect from Br atom, as indicted by theoretical calculation result. PMID:23673241

Wan, Pu; Zhao, Lun; Wang, Lisha; Xu, Guangyang

2013-08-01

181

Weak antiferromagnetic coupling for novel linear hexanuclear nickel(II) string complexes (Ni6 12+) and partial metal-metal bonds in their one-electron reduction products (Ni6 11+).  

PubMed

The preparation, crystal structures, magnetic properties and electrochemistry of novel linear hexanuclear nickel string complexes (Ni6(12+)) and their corresponding 1-e(-) reduction products (Ni6(11+)) are reported. In these complexes, the hexanickel chain is in a symmetrical arrangement (approximately D(4) symmetry) and is helically supported by four bpyany(2-) ligands [bpyany(2-) = the dianion of 2,7-bis(alpha-pyridylamino)-1,8-naphthyridine]. The Ni6(12+) complexes show that the two terminal nickel ions have high-spin states (S = 1) and the four inner ones have low-spin states (S = 0). The two terminal nickel ions exhibit weak antiferromagnetic coupling of ca.-5 cm(-1). All of Ni6(12+) complexes display three reversible redox couples at about -0.70, -0.20 and +1.10 V (vs. Ag/AgCl). The first reduction wave at about -0.20 V suggests facility of 1-e(-) reduction for the Ni(6)(12+) compounds. The reaction of Ni(6)(12+) complexes with hydrazine afforded the 1-e(-) reduction products (Ni6(11+)). As far as we are aware, the shortest bond distance of 2.202 A with a partial metal-metal bond was observed in Ni6(11+) compounds. The magnetic results of these Ni6(11+) compounds are in agreement with a localized model, in which the two terminal nickel ions are in a spin state of S = 1 whereas the central Ni3-Ni4 pair in a spin state of S = 1/2. The N6(11+) compounds show relatively strong antiferromagnetic coupling of about 60 cm(-1) between the terminal and the central dinickel ions. PMID:16802043

Chien, Chih-Hsien; Chang, Jung-Che; Yeh, Chen-Yu; Lee, Gene-Hsiang; Fang, Jim-Min; Song, You; Peng, Shie-Ming

2006-07-14

182

Localization of c-di-GMP-binding protein with the linear terminal complexes of Acetobacter xylinum.  

PubMed

Specific labeling of a single row of cellulose-synthesizing complexes (terminal complexes, TC subunits, TCs, or TC arrays) in Acetobacter xylinum by antibodies raised against a 93-kDa protein (the cyclic dignanylic acid-binding protein) has been demonstrated by using the sodium dodecyl sulfate (SDS)-freeze-fracture labeling (FRL) technique. The antibodies to the 93-kDa protein specifically recognized the TC subunits on the protoplasmic fracture (PF) face of the outer membrane in A. xylinum; however, nonlabeled TCs were also observed. Two types of TC subunits (particles or pits) are observed on the PF face of the outer membrane: (i) immunogold-labeled TCs showing a line of depressions (pits) with an indistinct particle array and (ii) nonlabeled TC subunits with a distinct single row of particle arrays. The evidence indicates that the labeling patterns differ with respect to the presence or absence of certain TC subunits remaining attached to the replica after SDS treatment. This suggests the presence of at least two TC components, one in the outer membrane and the other in the cytoplasmic membrane. If the TC component in the outer membrane is preferentially fractured and remains attached to the ectoplasmic fracture face (or outer leaflet) of the outer membrane, subsequent replica formation reveals a pit or depression with positive antibody labeling on the PF face of the outer membrane. If the TC component in the outer membrane remains with the PF face (or inner leaflet) of the outer membrane, the innermost TC component is removed during SDS treatment and labeling does not occur. SDS-FRL of TCs in A. xylinum has enabled us to provide the first topological molecular analysis of component proteins in a cellulose-synthesizing TC structure in a prokaryotic organism. PMID:11544230

Kimura, S; Chen, H P; Saxena, I M; Brown, R M; Itoh, T

2001-10-01

183

Localization of c-di-GMP-Binding Protein with the Linear Terminal Complexes of Acetobacter xylinum  

PubMed Central

Specific labeling of a single row of cellulose-synthesizing complexes (terminal complexes, TC subunits, TCs, or TC arrays) in Acetobacter xylinum by antibodies raised against a 93-kDa protein (the cyclic dignanylic acid-binding protein) has been demonstrated by using the sodium dodecyl sulfate (SDS)–freeze-fracture labeling (FRL) technique. The antibodies to the 93-kDa protein specifically recognized the TC subunits on the protoplasmic fracture (PF) face of the outer membrane in A. xylinum; however, nonlabeled TCs were also observed. Two types of TC subunits (particles or pits) are observed on the PF face of the outer membrane: (i) immunogold-labeled TCs showing a line of depressions (pits) with an indistinct particle array and (ii) nonlabeled TC subunits with a distinct single row of particle arrays. The evidence indicates that the labeling patterns differ with respect to the presence or absence of certain TC subunits remaining attached to the replica after SDS treatment. This suggests the presence of at least two TC components, one in the outer membrane and the other in the cytoplasmic membrane. If the TC component in the outer membrane is preferentially fractured and remains attached to the ectoplasmic fracture face (or outer leaflet) of the outer membrane, subsequent replica formation reveals a pit or depression with positive antibody labeling on the PF face of the outer membrane. If the TC component in the outer membrane remains with the PF face (or inner leaflet) of the outer membrane, the innermost TC component is removed during SDS treatment and labeling does not occur. SDS-FRL of TCs in A. xylinum has enabled us to provide the first topological molecular analysis of component proteins in a cellulose-synthesizing TC structure in a prokaryotic organism. PMID:11544230

Kimura, Satoshi; Chen, He Ping; Saxena, Inder M.; Brown, R. Malcolm; Itoh, Takao

2001-01-01

184

Blue/red linear dichroic emission from a highly anisotropic crystal of triarylmethane dye conjugated with phenoxo-zinc complexes.  

PubMed

We have developed a novel triphenylmethane-based hexanuclear zinc complex that exhibits peculiar photochemical and photophysical properties. Upon UV irradiation, the compound turned from colorless to reddish purple, while the color of emission turned from blue to red. The color change was attributed to an oxidation of the ligand part. It was suggested that an intramolecular energy-transfer mechanism operates to give rise to the red emission. The UV treatment of a single crystal results in simultaneous emission of orthogonally polarized blue and red light. This color switching, namely linear dichroic emission was so distinct that one can recognize with by sight through optical microscope. The columnar arrangement of molecules in the crystal clearly accounts for the observed polarization of the emission. PMID:21243678

Houjou, Hirohiko; Takezawa, Shunpei; Oyamada, Issei; Matsumura, Kazunari; Seino, Hidetake; Yoshikawa, Isao; Mizobe, Yasushi; Araki, Koji

2011-01-24

185

The two band model for halogen-bridged transition metal linear chain complexes  

SciTech Connect

Halogen-bridged transition-metal complexes have been of interest to chemists for many decades as dyes and strongly dichroic materials. However they have only recently begun to receive detailed consideration in the physics community. Their potential important arises because of: the increasing appreciation of strong, competing electron-electron and electron-phonon interactions in low-dimensional materials and the consequent need to expand many-body techniques. The MX materials offer a rapidly expanding, near single-crystal, class of quasi-1-D systems which can be ''tuned'' (by chemistry, pressure, doping, etc.) between various ground state extremes: from strong charge-disproportionation and large lattice distortion to weak charge-density-wave and small lattice distortion, to magnetic and undistorted; the opportunity to probe doping- and photo-induced local defect states (polarons, bipolarons, kinks, excitons) and their interactions in controlled environments and the same large range of ground states; and, the similarities between models and theoretical issues in these materials and the recently discovered oxide superconductors. The MX materials are also closely connected conceptually with mixed-stack charge-transfer salts. The MX class, then, is important in its own right, but also as a template for concepts and electronic structure techniques in strongly interacting (both electron-electron (e-e) and electron-phonon (e-p)), low dimensional electronic materials. This paper discusses the two band model for the isolated MX chains. 14 refs., 6 figs.

Bishop, A.R.; Gammel, J.T.; Loh, E.Y. Jr.; Phillpot, S.R.; Weber-Milbrodt, S.M.

1988-01-01

186

Strongly exponential symmetric spaces  

E-print Network

We study the exponential map of connected symmetric spaces and characterize, in terms of midpoints and of infinitesimal conditions, when it is a diffeomorphism, generalizing the Dixmier-Saito theorem for solvable Lie groups. We then give a geometric characterization of the (strongly) exponential solvable symmetric spaces as those spaces for which every triangle admits a unique double triangle. This work is motivated by Weinstein's quantization by groupoids program applied to symmetric spaces.

Yannick Voglaire

2014-04-06

187

Non-symmetrical tetradentate vanadyl Schiff base complexes derived from 1,2-phenylene diamine and 1,3-naphthalene diamine as catalysts for the oxidation of cyclohexene  

Microsoft Academic Search

Two series of the novel unsymmetrical diimino tetradentate Schiff bases derived from phenylenediamine and 1,3-naphthalene diamine and their vanadyl complexes were synthesized by template and non-template methods and characterized by 1H, 13C NMR, IR, UV–Vis and elemental analysis. These complexes are used as catalysts for the selective aerobic oxidation of cyclohexene. The catalytic activity increases as the number of electron-donor

Daver M Boghaei; Sajjad Mohebi

2002-01-01

188

Enantioselective Synthesis of Homoallylic Amines through Reactions of (Pinacolato)allylborons with Aryl-, Heteroaryl-, Alkyl- or Alkene-Substituted Aldimines Catalyzed by Chiral C1-Symmetric NHC–Cu Complexes  

PubMed Central

A catalytic method for enantioselective synthesis of homoallylamides through Cu-catalyzed reactions of stable and easily accessible (pinacolato)allylborons with aryl-, heteroaryl-,alkyl- or alkenyl-substituted N-phosphinoylimines is disclosed. Transformations are promoted by 1–5 mol % of readily accessible NHC–Cu complexes, derived from C1-symmetric imidazolinium salts, which can be prepared in multi-gram quantities in four steps from commercially available materials. Allyl additions deliver the desired products in up to quantitative yield and 98.5:1.5 enantiomeric ratio and are amenable to gram-scale operations. A mechanistic model accounting for the observed selectivity levels and trends is proposed. PMID:21341657

Vieira, Erika M.; Snapper, Marc L.; Hoveyda, Amir H.

2011-01-01

189

Viscosity in spherically symmetric accretion  

E-print Network

The influence of viscosity on the flow behaviour in spherically symmetric accretion, has been studied here. The governing equation chosen has been the Navier-Stokes equation. It has been found that at least for the transonic solution, viscosity acts as a mechanism that detracts from the effectiveness of gravity. This has been conjectured to set up a limiting scale of length for gravity to bring about accretion, and the physical interpretation of such a length-scale has been compared with the conventional understanding of the so-called "accretion radius" for spherically symmetric accretion. For a perturbative presence of viscosity, it has also been pointed out that the critical points for inflows and outflows are not identical, which is a consequence of the fact that under the Navier-Stokes prescription, there is a breakdown of the invariance of the stationary inflow and outflow solutions -- an invariance that holds good under inviscid conditions. For inflows, the critical point gets shifted deeper within the gravitational potential well. Finally, a linear stability analysis of the stationary inflow solutions, under the influence of a perturbation that is in the nature of a standing wave, has indicated that the presence of viscosity induces greater stability in the system, than has been seen for the case of inviscid spherically symmetric inflows.

Arnab K. Ray

2004-09-27

190

Transition metal(II) complexes of a novel symmetrical benzothiazole-based ligand: synthesis, spectral/structural characterization and fluorescence properties.  

PubMed

2,6-bis (benzothiazol-2-yl)-4-(tert-butyl) phenol ligand (HL) derived from o-aminothiophenol and 4-tert-butyl-2,6-diformylphenol was synthesized and characterized by using elemental analysis, FTIR, X-ray crystallographic analysis, (1)H and (13)C-NMR and UV-vis spectra. Its complexes with Cu (II), Ni (II) and Co (II) were prepared and isolated as solid products and characterized by elemental analysis, spectral techniques as well as magnetic susceptibility. The FTIR spectra showed that the benzothiazole-based ligand under investigation behaves as a bidentate ligand. The UV-vis spectra and magnetic moment data suggested an octahedral geometry around Ni (II) and Co (II) complexes, and tetragonal geometry for Cu (II) complex. Moreover, the evaluation of absorption and emission properties of the ligand and its complexes were carried out in different solvents. The ligand and its complexes showed absorption maxima in the range of 275 - 432 nm, and emission maxima from 367 to 581 nm in toluene, tetrahydrofuran and ethyl acetate. PMID:25212791

Gulcan, Mehmet; Karata?, Ya?ar; I??k, Sema; Öztürk, Gülsiye; Akba?, Esvet; ?ahin, Ertan

2014-11-01

191

Theoretical prediction of the linear isomers for rare gas-carbon disulfide complexes: He-CS?, Ne-CS?, and Ar-CS?.  

PubMed

Theoretical studies of the potential energy surfaces (PESs) and bound states are performed for rare gas-carbon disulfide complexes, He-CS2, Ne-CS2, and Ar-CS2. Three two-dimensional intermolecular PESs are constructed from ab initio data points which are calculated at the CCSD(T) level with aug-cc-pVTZ basis set supplemented with bond functions. We find that the three PESs have very similar features and each PES can be characterized by a global T-shaped minimum, two equivalent local linear minima, and the saddle points between them. The T-shaped isomer is energetically more stable than the linear isomer for each complex. The linear isomers, which have not been observed in experiment so far, are predicted from our PESs and further identified by bound state calculations. Moreover, we assign several intermolecular vibrational states for both the T-shaped and linear isomers of the three complexes via the analysis of wavefunctions. The corresponding vibrational frequencies are calculated from the bound state energies for these assigned states. These frequencies could be helpful for further experimental studies, especially for the linear isomers. We also calculate the rovibrational transition frequencies for the three T-shaped isomers and the pure rotational transition frequencies for the linear isomers, respectively. The accuracy of the PESs is validated by the good agreement between theoretical and experimental results for the rovibrational transition frequencies and spectroscopic parameters. PMID:24655183

Zang, Limin; Dai, Wei; Zheng, Limin; Duan, Chuanxi; Lu, Yunpeng; Yang, Minghui

2014-03-21

192

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

E-print Network

Apr 26, 2013 ... tages of increasing either memory, conditioning, or computational costs. .... matrices, or applications in quantum dynamics, electromagnetics, and power systems, ... ?1; c and s cosine and sine of some angle ?; ek the kth unit vector; ...... ables, whose values were drawn from the standard uniform distribution ...

Sou-Cheng (Terrya) Choi

2013-04-26

193

Noncommutative symmetric functions  

Microsoft Academic Search

This paper presents a noncommutative theory of symmetric functions, based on the notion of quasi-determinant. We begin with a formal theory, corresponding to the case of symmetric functions in an infinite number of independent variables. This allows us to endow the resulting algebra with a Hopf structure, which leads to a new method for computing in descent algebras. It also

Israel Gelfand; D. Krob; Alain Lascoux; B. Leclerc; V. S. Retakh; J.-Y. Thibon

1994-01-01

194

Symmetric network computation  

Microsoft Academic Search

We introduce a simple new model of distributed compu- tation | nite-state symmetric graph automata (FSSGA) | which captures the qualitative properties common to fault-tolerant distributed algorithms. Roughly speaking, the computation evolves homogeneously in the entire network, with each node acting symmetrically and with limited re- sources. As a building block, we demonstrate the equiv- alence of two automaton models

David Pritchard; Santosh Vempala

2006-01-01

195

Multimetallic arrays: symmetrical bi-, tri- and tetrametallic complexes based on the group 10 metals and the functionalisation of gold nanoparticles with nickel-phosphine surface units.  

PubMed

Homobimetallic complexes of nickel, palladium and platinum, [(L2M)2(S2CNC4H8NCS2)]2+, are formed on reaction of the piperazine bis(dithiocarbamate) linker, KS2CNC4H8NCS2K, with [MCl2L2] (M=Ni, L2=dppe, dppf; M=Pd, L2=dppf; M=Pt, L=PEt3, PMePh2, PPh3, L2=dppf). [{Pd(C,N-C6H4CH2NMe2)}2(S2CNC4H8NCS2)] can be obtained in the same way. On reaction of [MCl2L2] (M=Pd, Pt) with the zwitterion S2CNC4H8NH2, a symmetrisation process occurs to yield a mixture of the complexes [M(S2CNC4H8NH2)L2]2+ and [(L2M)2(S2CNC4H8NCS2)]2+. However, the monometallic complexes [L2Ni(S2CNC4H8NH2)]2+ (L2=dppe, dppf) and [(L2Ni)2(S2CNC4H8NCS2)]2+ can be prepared without ready symmetrisation. Starting from the previously reported [(dppm)Ru(S2CNC4H8NH2)]2+, the heterotrimetallic products [(dppm)Ru(S2CNC4H8NCS2)M(dppf)]2+ (M=Pd, Pt) can be prepared without symmetrisation occurring. The crystal structures of five complexes are reported. The metalla-dithiocarbamate complexes [L2Ni(S2CNC4H8NCS2)] (L2=dppe, dppf) were used to functionalise the surface of gold nanoparticles by the displacement of a citrate shell to yield NiAu and FeNiAu materials. PMID:19417934

Knight, Edward R; Leung, Nina H; Lin, Yvonne H; Cowley, Andrew R; Watkin, David J; Thompson, Amber L; Hogarth, Graeme; Wilton-Ely, James D E T

2009-05-21

196

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

SciTech Connect

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 ?{sub rp,rw}?complex gain G{sub i} to optimize in the presence of rotation in this regime with ??>??{sub rp,iw} is presented. The effect of imaginary gain with tangential sensors is more complicated but essentially destabilizes above and below ?{sub rp,iw}.

Brennan, D. P. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States); Finn, J. M. [Applied Mathematics and Plasma Physics, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2014-10-15

197

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

198

Systems of Differential Equations with Skew-Symmetric, Orthogonal Matrices  

ERIC Educational Resources Information Center

The solution of a system of linear, inhomogeneous differential equations is discussed. The particular class considered is where the coefficient matrix is skew-symmetric and orthogonal, and where the forcing terms are sinusoidal. More general matrices are also considered.

Glaister, P.

2008-01-01

199

Technetium and rhenium in five-coordinate symmetrical and dissymmetrical nitrido complexes with alkyl phosphino-thiol ligands. Synthesis and structural characterization.  

PubMed

The reactivity of bulky alkylphosphino-thiol ligands (PSH) toward nitride-M(V, VI) (M = Tc/Re) precursors was investigated. Neutral five-coordinate monosubstituted complexes of the type [M(N)(PS)Cl(PPh(3))] (Tc1-4, Re1-2) were prepared in moderate to high yields. It was found that these [M(N)(PS)Cl(PPh(3))] species underwent ligand-exchange reactions under mild conditions when reacted with bidentate mononegative ligands having soft donor atoms such as dithiocarbamates (NaL(n)) to afford stable dissymmetrical mixed-substituted complexes of the type [M(N)(PS)(L(n))] (Tc5,8-10, Re5-9) containing two different bidentate chelating ligands bound to the [M[triple bond]N](2+) moiety. In these reactions, the dithiocarbamate replaced the two labile monodentate ligands (Cl and PPh(3)) leaving the [M(N)(PS)](+) building block intact. In the above reactions, technetium and rhenium were found to behave in a similar way. Instead, under more drastic conditions, reactions of PSH with [M(N)Cl(2)(PPh(3))(2)] gave a mixture of monosubstituted [M(N)(PS)Cl(PPh(3))] and bis-substituted species [M(N)(PS)(2)] (Tc11-14) in the case of technetium, whereas only monosubstituted [M(N)(PS)Cl(PPh(3))] complexes were recovered for rhenium. All isolated products were characterized by elemental analysis, IR and multinuclear ((1)H, (13)C, and (31)P) NMR spectroscopies, ESI MS spectrometry, and X-ray crystal structure determination of the representative monosubstituted [Tc(N)(PStbu)Cl(PPh(3))] (Tc4) and mixed-substituted [Re(N)(PScy)(L(3))] (Re7) and [Re(N)(PSiso)(L(4))] (Re9) complexes. The latter rhenium complexes represent the first example of a square-pyramidal nitrido Re species with the basal plane defined by a PS(3) donor set. Monosubstituted [M(N)(PS)Cl(PPh(3))] species bearing the substitution-inert [M(N)(PS)](+) moieties act as suitable building blocks proposed for the construction of new classes of dissymmetrical nitrido compounds with potential application in the development of essential and target specific (99m)Tc and (188)Re radiopharmaceuticals for imaging and therapy, respectively. PMID:19007158

Bolzati, Cristina; Cavazza-Ceccato, Mario; Agostini, Stefania; Tisato, Francesco; Bandoli, Giuliano

2008-12-15

200

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

201

Condition Number Complexity of an Elementary Algorithm for Computing a Reliable Solution of a Conic Linear System  

Microsoft Academic Search

. A conic linear system is a system of the form (FP d ) Ax = b x 2 CX ; where A : X ! Y is a linear operator between n- and m-dimensional linear spaces X and Y , b 2 Y , and CX X is a closed convex cone. The data for the system is d

Marina Epelman; Robert M. Freund

1997-01-01

202

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.

National Security Agency Central Security Service

2009-04-24

203

1 Weakly Symmetric Spaces  

E-print Network

well known consequence of being naturally reductive is that all geo- desics are images of one parameter] are the distance spheres in rank 1 symmetric spaces and tubes around some totally geodesic submanifolds in rank 1

Ziller, Wolfgang

204

Plane Symmetric Gravitational Collapse  

E-print Network

In this paper, we derive the general formulation by considering two arbitrary plane symmetric spacetimes using Israel's method. As an example, we apply this formulation to known plane symmetric spacetimes. We take the Taub's static metric in the interior region whereas Kasner's non-static metric in the exterior region. It is shown that the plane collapses in some cases whereas it expands in some other cases.

M. Sharif; Zahid Ahmad

2007-09-20

205

NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS Numer. Linear Algebra Appl. (2012)  

E-print Network

NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS Numer. Linear Algebra Appl. (2012) Published online for linear systems in the case of a standard quadratic optimization problem with symmetric positive definite- erates convergence of the alternating least squares (ALS) optimization method for the canonical tensor

De Sterck, Hans

2012-01-01

206

One-pot synthesis of symmetric and asymmetric p-quinone ligands and unprecedented substituent induced reactivity in their dinuclear ruthenium complexes.  

PubMed

The compounds 2-[2-(trifluoromethyl)-anilino]-5-hydroxy-1,4-benzoquinone (L(1)), 2,5-di-[2-(trifluoromethyl)-anilino]-1,4-benzoquinone (L(2)), 2-[2-(methylthio)-anilino]-5-hydroxy-1,4-benzoquinone (L(3)), and 2,5-di-[2-(methylthio)-anilino]-1,4-benzoquinone (L(4)) were prepared in high yields by reacting 2,5-dihydroxy-1,4-benzoquinone with the corresponding amines in a one-pot synthesis in refluxing acetic acid. This straightforward and "green" synthesis delivers biologically relevant asymmetric p-quinones such as L(1) and L(3) in a rare, simple, one-step process. The proposed synthetic route is general and can be applied to generate a variety of such molecules with different substituents on the nitrogen atoms. Structural characterization of L(2) and L(4) shows electron delocalization across the "upper" and "lower" parts of the molecule, thus showing the importance of charge separated species in the proper description of such molecules. Reactions of these ligands with [Cl(?(6)-Cym)Ru(?-Cl)(2)Ru(?(6)-Cym)Cl] (Cym = p-Cymene = 1-isopropyl-4-methyl-benzene) in the presence of a base result in the formation of complexes [{Cl(?(6)-Cym)Ru}(2)(?-L(-2H)(1))] (1), [{Cl(?(6)-Cym)Ru}(2)(?-L(-2H)(2))] (2), [{Cl(?(6)-Cym)Ru}(2)(?-L(-2H)(3))] (3), and [{Cl(?(6)-Cym)Ru}(2)(?-L(-2H)(4))] (4). Structural characterization of 2 and 4 shows a rare syn-coordination of the chloride atoms. The SMe groups in 3 and 4 are not coordinated to the ruthenium center, and the bridging ligands thus function in a bis-bidentate form. Abstraction of the chloride atoms in these complexes with AgClO(4) in CH(3)CN results in the expected formation of solvent substituted complexes [{(CH(3)CN)(?(6)-Cym)Ru}(2)(?-L(-2H)(1))][ClO(4)](2) (5[ClO(4)](2)) and [{(CH(3)CN)(?(6)-Cym)Ru}(2)(?-L(-2H)(2))][ClO(4)](2) (6[ClO(4)](2)) with the ligands where there are no additional donor atoms on the nitrogen substituents. The same chloride abstraction reaction in the cases of 3 and 4 leads to an unprecedented substituent induced release of the Cym ligand, resulting in complexes of the form [(CH(3)CN)(?(6)-Cym)Ru(?-L(-2H)(3))Ru(CH(3)CN)(3)][ClO(4)](2) (7[ClO(4)](2)) and [{(CH(3)CN)(3)Ru}(2)(?-L(-2H)(4))][ClO(4)](2) (8[ClO(4)](2)), where the SMe groups are now coordinated to the metal center. In the case of complex 3, which contains an asymmetric bridging ligand, Cym release is observed only at the side that contains an additional SMe donor, thus proving the necessity of such donor substituents for the observed reactivity. The increase in Lewis acidity at the ruthenium center on chloride abstraction is made responsible for SMe coordination and the rigidity of the ligand systems, and their concomitant failure to coordinate in a "fac" manner as is required for a piano stool configuration results in the eventual Cym release. The bridging ligand which then coordinates in a bis-meridional fashion in 8[ClO(4)](2) results in a bis-pincer type of coordination. These observations were validated by a structural analysis of 8[ClO(4)](2). The results show the potential hemilabile character of ligands such as L(3) and L(4). Electrochemical and spectroscopic investigations are reported on 8[ClO(4)](2), and substitution reactions of the CH(3)CN molecules are presented to show the use of 8[ClO(4)](2) as a versatile precursor for other reactions. PMID:21214266

Schweinfurth, David; Das, Hari Sankar; Weisser, Fritz; Bubrin, Denis; Sarkar, Biprajit

2011-02-01

207

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

208

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

209

Stability of rotor systems: A complex modelling approach  

Microsoft Academic Search

The dynamics of a large class of rotor systems can be modelled by a linearized complex matrix dierential equation of second order, M¨ +( D +iG)_z +( K +iN)z =0 , where the system matrices M;D;G;K and N are real symmetric. Moreover M and K are assumed to be positive denite and D;G andN to be positive semidenite. The complex

W. Kliem; C. Pommer; J. Stoustrup

1998-01-01

210

Construction of dynamics and time-ordered exponential for unbounded non-symmetric Hamiltonians  

SciTech Connect

We prove under certain assumptions that there exists a solution of the Schrödinger or the Heisenberg equation of motion generated by a linear operator H acting in some complex Hilbert space H, which may be unbounded, not symmetric, or not normal. We also prove that, under the same assumptions, there exists a time evolution operator in the interaction picture and that the evolution operator enjoys a useful series expansion formula. This expansion is considered to be one of the mathematically rigorous realizations of so-called “time-ordered exponential,” which is familiar in the physics literature. We apply the general theory to prove the existence of dynamics for the mathematical model of Quantum Electrodynamics quantized in the Lorenz gauge, the interaction Hamiltonian of which is not even symmetric or normal.

Futakuchi, Shinichiro; Usui, Kouta [Department of Mathematics, Hokkaido University, 060-0810 Sapporo (Japan)

2014-06-15

211

A Minimally Symmetric Higgs Boson  

E-print Network

Models addressing the naturalness of a light Higgs boson typically employ symmetries, either bosonic or fermionic, to stabilize the Higgs mass. We consider a setup with the minimal amount of symmetries: four shift symmetries acting on the four components of the Higgs doublet, subject to the constraints of linearly realized SU(2)xU(1) electroweak symmetry. Up to terms that explicitly violate the shift symmetries, the effective lagrangian can be derived, irrespective of the spontaneously broken group G in the ultraviolet, and is universal in all models where the Higgs arises as a pseudo-Nambu-Goldstone boson (PNGB). Very high energy scatterings of vector bosons could provide smoking gun signals of a minimally symmetric Higgs boson.

Ian Low

2014-12-05

212

Differential Salt-Induced Dissociation of the p53 Protein Complexes with Circular and Linear Plasmid DNA Substrates Suggest Involvement of a Sliding Mechanism  

PubMed Central

A study of the effects of salt conditions on the association and dissociation of wild type p53 with different ~3 kbp long plasmid DNA substrates (supercoiled, relaxed circular and linear, containing or lacking a specific p53 binding site, p53CON) using immunoprecipitation at magnetic beads is presented. Salt concentrations above 200 mM strongly affected association of the p53 protein to any plasmid DNA substrate. Strikingly different behavior was observed when dissociation of pre-formed p53-DNA complexes in increased salt concentrations was studied. While contribution from the p53CON to the stability of the p53-DNA complexes was detected between 100 and 170 mM KCl, p53 complexes with circular DNAs (but not linear) exhibited considerable resistance towards salt treatment for KCl concentrations as high as 2 M provided that the p53 basic C-terminal DNA binding site (CTDBS) was available for DNA binding. On the contrary, when the CTDBS was blocked by antibody used for immunoprecipitation, all p53-DNA complexes were completely dissociated from the p53 protein in KCl concentrations ?200 mM under the same conditions. These observations suggest: (a) different ways for association and dissociation of the p53-DNA complexes in the presence of the CTDBS; and (b) a critical role for a sliding mechanism, mediated by the C-terminal domain, in the dissociation process. PMID:25647416

Šebest, Peter; Brázdová, Marie; Fojta, Miroslav; Pivo?ková, Hana

2015-01-01

213

Bilateral symmetrical frontoparietal polymicrogyria.  

PubMed

A patient with bilateral symmetrical frontoparietal polymicrogyria is reported. Severe developmental delay, mental retardation, spastic tetraplegia, and seizures were the main clinical features. Magnetic resonance imaging revealed bilateral thick cortex with irregular gyri and festoon-like grey-white matter junction in the frontoparietal areas. Bilateral frontoparietal polymicrogyria might represent either a severe form of a spectrum of malformations involving the frontoparietal area or a further variety of the congenital bilateral symmetrical polymicrogyria syndromes in addition to bilateral frontal polymicrogyria, bilateral perisylvian syndrome, and bilateral parasagittal parieto-occipital polymicrogyria. PMID:12374591

Sztriha, László; Nork, Michael

2002-01-01

214

Symmetrohedra: Polyhedra from Symmetric  

E-print Network

Symmetrohedra: Polyhedra from Symmetric Placement of Regular Polygons Craig S. Kaplan University://www.georgehart.com george@georgehart.com Abstract In the quest for new visually interesting polyhedra with regular faces, we axes of a polyhedral symmetry group. This new technique can be used to generate many existing polyhedra

Kaplan, Craig S.

215

Yangian symmetric correlators  

NASA Astrophysics Data System (ADS)

Similarity transformations and eigenvalue relations of monodromy operators composed of Jordan-Schwinger type L matrices are considered and used to define Yangian symmetric correlators of n-dimensional theories. Explicit expressions are obtained and relations are formulated. In this way basic notions of the Quantum inverse scattering method provide a convenient formulation for high symmetry and integrability not only in lower dimensions.

Chicherin, D.; Kirschner, R.

2013-12-01

216

Symmetric Cryptography in Javascript  

Microsoft Academic Search

We take a systematic approach to developing a symmetric cryptography library in Javascript. We study various strategies for optimizing the code for the Javascript interpreter, and observe that traditional crypto optimization techniques do not apply when implemented in Javascript. We propose a number of optimizations that reduce both running time and code size. Our optimized library is about four times

Emily Stark; Michael Hamburg; Dan Boneh

2009-01-01

217

Condition number complexity of an elementary algorithm for computing a reliable solution of a conic linear system  

Microsoft Academic Search

.   A conic linear system is a system of the form¶¶(FP\\u000a d\\u000a \\u000a )Ax=b¶x?C\\u000a \\u000a X\\u000a ,¶¶where A:X?Y is a linear operator between n- and m-dimensional linear spaces X and Y, b?Y, and C\\u000a \\u000a X\\u000a \\u000a ?X is a closed convex cone. The data for the system is d=(A,b). This system is “well-posed” to the extent that (small) changes in the data d=(A,b)

Marina Epelman; Robert M. Freund

2000-01-01

218

Bilateral and symmetrical tinea mammae  

E-print Network

present a case of bilateral tinea mammae, which has not beenLetter Bilateral and symmetrical tinea mammae Murat Y?lmaz,bilateral symmetrical tinea infection on the breast area. Reported unilateral tinea mammae

Yilmaz, Murat; Kavak, Ayse; Yamaner, Nalan Jale

2013-01-01

219

Symmetric form of governing equations for capillary fluids  

E-print Network

In classical continuum mechanics, quasi-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 depends not only on the density but also on its derivatives with respect to space variables. Consequently, the governing equations belong to the class of dispersive systems. In that case we propose a symmetric form of governing equations which is different from the classical Godunov -Friedrichs - Lax representation. This new symmetric form implies the stability of constant solutions.

Sergey Gavrilyuk; Henri Gouin

2008-02-12

220

Complex Normal Form for Strongly Non-Linear Vibration Systems Exemplified by DUFFING-VAN Der Pol Equation  

NASA Astrophysics Data System (ADS)

We extend the normal form method to study the asymptotic solutions of strongly non-linear oscillatorsu+?2u=f](u,u), wheref(u,u) contains only linear and cubic non-linear terms. The novel contribution is the ansatzu=?+?,u=i?1(?-?) where ?1is to be determined, allowing for the change of the fundamental frequency during the course of vibration, rather than usingu=?+?,u=i?(?-?) as suggested by Nayfeh. With the present method, not only the stability of the periodic solutions but also the asymptotic expressions for the periodic solutions can be obtained easily. The results obtained by the method presented coincide very well with the results obtained by numerical integration for the Duffing-van der Pol oscillator withf(u,u)=?(1-u2)u-?u3. When ?=?=?=1, Nayfeh's method givers qualitatively different results from the numerical integration while our method works well even when ?=1, ?=?=3, since Nayfeh's method is based on weak non-linearities and ?=1, ?=?=3 is beyond the valid range of assumption.

Leung, A. Y. T.; Zhang, Q. C.

1998-06-01

221

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

222

Synthesis, structure, catalytic and calculated non-linear optical properties of cis- and trans-, mer-chlorobis(triphenyl phosphine/triphenyl arsine)-dipicolinato ruthenium III complexes  

NASA Astrophysics Data System (ADS)

The new mononuclear Ru III complexes cis-, mer-[Ru( k3-dipic)(EPh 3) 2Cl]·2H 2O (E = P ( 1), As ( 2)), (L = 2,6-pyridyldicarboxylate; dipic) have been synthesized and characterized. The X-ray crystal structure of 1 reveals that the coordination geometry around the Ru III center is distorted octahedral in which three sites are occupied by tridentate dipic ligand and remaining three sites are occupied by two mutually cis triphenyl phosphine ligands and one chloride ions. In chloroform solvent, cis-, mer-[Ru( k3-dipic)(EPh 3) 2Cl]·2H 2O (E = P ( 1), As ( 2)) complexes undergoes thermal rearrangement to more stable trans-, mer-[Ru( k3-dipic)(EPh 3) 2Cl] (E = P( 3), As( 4)) complexes. Complexes 1 and 2 show rhombic EPR spectral features, while complex 3 and 4 show tetragonal distortion. The new Ru III complexes 1 and 2 display both Ru III-Ru II reduction and Ru III-Ru IV oxidation processes. These geometric isomers exhibit textbook differences both in spectroscopic as well as structural properties in the solid state. The new complexes 1 and 2 were found to catalyze the oxidation of alcohols to carbonyl derivatives using N-methyl morpholine- N-oxide as co-oxidant. The first static hyperpolarizability ( ?) for all of the complexes have been investigated by density functional theory (DFT) which suggests ? value increases from trans to cis form. Also, the solvent-induced effects on the non-linear optical properties (NLO) were studied by using self-consistent reaction field (SCRF) method. As the solvent polarity increases, the ? value increases monotonically. The electronic absorption bands of 1 have been assigned by time dependent density functional theory (TD-DFT).

Trivedi, Manoj; Nagarajan, R.; Kumar, Abhinav; Singh, Narendra K.; Rath, Nigam P.

2011-05-01

223

On the optimum bit orders with respect to the state complexity of trellis diagrams for binary linear codes  

NASA Technical Reports Server (NTRS)

It was shown earlier that for a punctured Reed-Muller (RM) code or a primitive BCH code, which contains a punctured RM code of the same minimum distance as a large subcode, the state complexity of the minimal trellis diagram is much greater than that for an equivalent code obtained by a proper permutation on the bit positions. To find a permutation on the bit positions for a given code that minimizes the state complexity of its minimal trellis diagram is an interesting and challenging problem. This permutation problem is related to the generalized Hamming weight hierarchy of a code, and is shown that for RM codes, the standard binary order of bit positions is optimum at every bit position with respect to the state complexity of a minimal trellis diagram by using a theorem due to Wei. The state complexity of trellis diagram for the extended and permuted (64, 24) BCH code is discussed.

Kasami, Tadao; Takata, Toyoo; Fujiwara, Toru; Lin, Shu

1993-01-01

224

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

225

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

226

Symmetric iterative interpolation processes  

Microsoft Academic Search

Using a baseb and an even number of knots, we define a symmetric iterative interpolation process. The main properties of this process come from an associated functionF. The basic functional equation forF is thatF(t\\/b)=snF(n\\/b)F(t-n). We prove thatF is a continuous positive definite function. We find almost precisely in which Lipschitz classes derivatives ofF belong. If a functiony is defined only

Gilles Deslauriers; Serge Dubuc

1989-01-01

227

Enzymatic nanoreactors for environmentally benign biotransformations. 1. Formation and catalytic activity of supramolecular complexes of laccase and linear-dendritic block copolymers.  

PubMed

We describe the construction of enzymatic nanoreactors through noncovalent envelopment of a glycoprotein by amphiphilic linear-dendritic AB or ABA copolymers. The synthetic procedure is based on the regioselective adsorption of dendritic poly(benzyl ether)-block-linear poly(ethylene glycol)-block-dendritic poly(benzyl ether) or linear poly(ethylene oxide)-block-dendritic poly(benzyl ether) copolymers onto the oxidative enzyme laccase from Trametes versicolor in aqueous medium. The complexes formed have improved catalytic activity compared with the native enzyme (77-85 nkat/mL vs 60 nkat/mL, respectively) and are more stable at elevated temperatures up to 70 degrees C. Experiments with deglycosylated laccase confirm that the glycoside fragments in the native enzyme serve as the anchor sites for the linear-dendritic copolymers. The enzymatic nanoreactors are able to effectively oxidize series of substrates: phenolic compounds (syringaldazine) and hydrophobic polyaromatic hydrocarbons (anthracene and benzo[a]pyrene) under "green" chemistry conditions. PMID:18257555

Gitsov, Ivan; Hamzik, James; Ryan, Joseph; Simonyan, Arsen; Nakas, James P; Omori, Shigetoshi; Krastanov, Albert; Cohen, Tomer; Tanenbaum, Stuart W

2008-03-01

228

Bcl2 inhibits recruitment of Mre11 complex to DNA double-strand breaks in response to high-linear energy transfer radiation  

PubMed Central

High-linear energy transfer ionizing radiation, derived from high charge (Z) and energy (E) (HZE) particles, induces clustered/complex DNA double-strand breaks (DSBs) that include small DNA fragments, which are not repaired by the non-homologous end-joining (NHEJ) pathway. The homologous recombination (HR) DNA repair pathway plays a major role in repairing DSBs induced by HZE particles. The Mre11 complex (Mre11/Rad50/NBS1)-mediated resection of DSB ends is a required step in preparing for DSB repair via the HR DNA repair pathway. Here we found that expression of Bcl2 results in decreased HR activity and retards the repair of DSBs induced by HZE particles (i.e. 56iron and 28silicon) by inhibiting Mre11 complex activity. Exposure of cells to 56iron or 28silicon promotes Bcl2 to interact with Mre11 via the BH1 and BH4 domains. Purified Bcl2 protein directly suppresses Mre11 complex-mediated DNA resection in vitro. Expression of Bcl2 reduces the ability of Mre11 to bind DNA following exposure of cells to HZE particles. Our findings suggest that, after cellular exposure to HZE particles, Bcl2 may inhibit Mre11 complex-mediated DNA resection leading to suppression of the HR-mediated DSB repair in surviving cells, which may potentially contribute to tumor development. PMID:25567982

Xie, Maohua; Park, Dongkyoo; You, Shuo; Li, Rui; Owonikoko, Taofeek K.; Wang, Ya; Doetsch, Paul W.; Deng, Xingming

2015-01-01

229

Plane Symmetric, Cylindrically Symmetric and Spherically Symmetric Black Holes 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

2014-12-30

230

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

231

Synthesis, structure, and magnetic characterization of a C3-symmetric Mn(III)3Cr(III) assembly: molecular recognition between a trinuclear Mn(III) triplesalen complex and a fac-triscyano Cr(III) complex.  

PubMed

The reaction of the tris(tetradentate) triplesalen ligand H(6)talen(t-Bu(2)), which provides three salen-like coordination environments bridged in a meta-phenylene arrangement by a phloroglucinol backbone, with Mn(II) salts under aerobic conditions, affords, in situ, the trinuclear Mn(III) triplesalen complex [(talen(t-Bu(2))){Mn(III)(solv)(n)}(3)](3+). This species then reacts with [(Me(3)tacn)Cr(CN)(3)] to form the tetranuclear complex [{(talen(t-Bu(2)))Mn(III)(3)}{(Me(3)tacn)Cr(CN)(3)}](3+) ([Mn(III)(3)Cr(III)](3+)). The regular ligand folding observed in the trinuclear triplesalen complex preorganizes the three metal ions for the reaction with three facially coordinated nitrogen atoms of [(Me(3)tacn)Cr(CN)(3)]. [{(talen(t-Bu(2)))(Mn(III)(MeOH))(3)}{(Me(3)tacn)Cr(CN)(3)}](ClO(4))(3) (1) was characterized by infrared spectroscopy, elemental analysis, mass spectrometry, electron absorption spectroscopy, and magnetic measurements. The molecular structure was established for the acetate-substituted derivative [{(talen(t-Bu(2)))(Mn(III)(MeOH))(2)(Mn(III)(OAc))}{(Me(3)tacn)Cr(CN)(3)}](ClO(4))(2) (2) by single-crystal X-ray diffraction. Variable-temperature-variable-field and mu(eff) versus T magnetic data have been analyzed in detail by full-matrix diagonalization of the appropriate spin-Hamiltonian, consisting of isotropic exchange, zero-field splitting, and Zeeman interaction components. Satisfactory reproduction of the experimental data has been obtained for the parameters J(Mn-Cr) = -0.12 +/- 0.04 cm(-1), J(Mn-Mn) = -0.70 +/- 0.03 cm(-1), and D(Mn) = -3.0 +/- 0.4 cm(-1). These generate a triply degenerate pseudo S(t) = 7/2 spin manifold, which cannot be appropriately described by a giant spin model and which exhibits a weak easy-axis magnetic anisotropy. This is corroborated by the onset of a frequency-dependent chi'' signal at low temperatures, demonstrating a slow relaxation of the magnetization indicative of 1 being a single-molecule magnet. Comparing the properties to those of the heptanuclear analogue [{(talen(t-Bu(2)))Mn(III)(3)}(2){Cr(III)(CN)(6)}](3+) ([Mn(III)(6)Cr(III)](3+)) formed by the reaction of 2 equiv of [(talen(t-Bu(2))){Mn(III)(solv)(n)}(3)](3+) with 1 equiv of [Cr(CN)(6)](3-) [Glaser, T.; Heidemeier, M.; Weyhermüller, T.; Hoffmann, R.-D.; Rupp, H.; Müller, P. Angew. Chem. Int. Ed., 2006, 45, 6033-6037] demonstrates a lower driving force for formation, a strongly reduced J(Mn-Cr) exchange, a slightly reduced J(Mn-Mn) exchange, and a significantly longer Mn-N(N[triple bond]C) bond length in [Mn(III)(3)Cr(III)](3+). Taking into account magneto-structural correlations establishes a supramolecular interaction between the two [(talen(t-Bu(2)))Mn(III)(3)](3+) subunits in [Mn(III)(6)Cr(III)](3+) responsible for the structural distortion and the short Mn-N(N[triple bond]C) distance which results in a strong J(Mn-Cr) exchange and thus [Mn(III)(6)Cr(III)](3+) being a single-molecule magnet with a relatively high effective anisotropy barrier of 25.4 K. PMID:19803531

Freiherr von Richthofen, Carl-Georg; Stammler, Anja; Bögge, Hartmut; DeGroot, Marty W; Long, Jeffrey R; Glaser, Thorsten

2009-11-01

232

Spectroscopic demonstration of a large antisymmetric exchange contribution to the spin-frustrated ground state of a D3 symmetric hydroxy-bridged trinuclear Cu(II) complex: ground-to-excited state superexchange pathways.  

PubMed

The magnetic and electronic properties of a spin-frustrated ground state of an antiferromagnetically coupled 3-fold symmetric trinuclear copper complex (TrisOH) is investigated using a combination of variable-temperature variable-field magnetic circular dichroism (VTVH MCD) and powder/single-crystal EPR. Direct evidence for a low-lying excited S = (1)/(2) state from the zero-field split ground (2)E state is provided by the nonlinear dependence of the MCD intensity on 1/T and the nesting of the VTVH MCD isotherms. A consistent zero-field splitting (Delta) value of approximately 65 cm(-1) is obtained from both approaches. In addition, the strong angular dependence of the single-crystal EPR spectrum, with effective g-values from 2.32 down to an unprecedented 1.2, requires in-state spin-orbit coupling of the (2)E state via antisymmetric exchange. The observable EPR intensities also require lowering of the symmetry of the trimer structure, likely reflecting a magnetic Jahn-Teller effect. Thus, the Delta of the ground (2)E state is shown to be governed by the competing effects of antisymmetric exchange (G = 36.0 +/- 0.8 cm(-1)) and symmetry lowering (delta = 17.5 +/- 5.0 cm(-1)). G and delta have opposite effects on the spin distribution over the three metal sites where the former tends to delocalize and the latter tends to localize the spin of the S(tot) = (1)/(2) ground state on one metal center. The combined effects lead to partial delocalization, reflected by the observed EPR parallel hyperfine splitting of 74 x 10(-4) cm(-1). The origin of the large G value derives from the efficient superexchange pathway available between the ground d(x2-y2) and excited d(xy) orbitals of adjacent Cu sites, via strong sigma-type bonds with the in-plane p-orbitals of the bridging hydroxy ligands. This study provides significant insight into the orbital origin of the spin Hamiltonian parameters of a spin-frustrated ground state of a trigonal copper cluster. PMID:15453791

Yoon, Jungjoo; Mirica, Liviu M; Stack, T Daniel P; Solomon, Edward I

2004-10-01

233

Scattering in spherically symmetric media.  

PubMed

The scattering problem within a multilayered spherically symmetric medium due to a source of perturbation located in the external region is considered. Assuming that the refractive index and its derivative vary continuously, with the exception of a finite number of jump discontinuities, the electromagnetic field vectors are represented in terms of various well-known potentials suitable for describing the azimuthal dependence of the incident wave. The linear dependence between the permittivity and the specific conductivity is proved to be equivalent to the vanishing of the electric charge density. Exact expressions for the field energy characteristics in the external region have been derived without any supplementary suppositions with respect to the wave zone. Scattering from a dielectric coated sphere, whose refractive index is a continuous function while its derivative has two jump discontinuity points (a modified Mie problem), has been studied. The generalized van de Hulst phase angle transformation is introduced and used to show the coincidence of the cross sections for scattering and extinction for the transparent spherical shell mentioned. PMID:20212651

Perelman, A Y

1979-07-01

234

Linear coding of complex sound spectra by discharge rate in neurons of the medial nucleus of the trapezoid body (MNTB) and its inputs  

PubMed Central

The interaural level difference (ILD) cue to sound location is first encoded in the lateral superior olive (LSO). ILD sensitivity results because the LSO receives excitatory input from the ipsilateral cochlear nucleus and inhibitory input indirectly from the contralateral cochlear nucleus via glycinergic neurons of the ipsilateral medial nucleus of the trapezoid body (MNTB). It is hypothesized that in order for LSO neurons to encode ILDs, the sound spectra at both ears must be accurately encoded via spike rate by their afferents. This spectral-coding hypothesis has not been directly tested in MNTB, likely because MNTB neurons have been mostly described and studied recently in regards to their abilities to encode temporal aspects of sounds, not spectral. Here, we test the hypothesis that MNTB neurons and their inputs from the cochlear nucleus and auditory nerve code sound spectra via discharge rate. The Random Spectral Shape (RSS) method was used to estimate how the levels of 100-ms duration spectrally stationary stimuli were weighted, both linearly and non-linearly, across a wide band of frequencies. In general, MNTB neurons, and their globular bushy cell inputs, were found to be well-modeled by a linear weighting of spectra demonstrating that the pathways through the MNTB can accurately encode sound spectra including those resulting from the acoustical cues to sound location provided by head-related directional transfer functions (DTFs). Together with the anatomical and biophysical specializations for timing in the MNTB-LSO complex, these mechanisms may allow ILDs to be computed for complex stimuli with rapid spectrotemporally-modulated envelopes such as speech and animal vocalizations and moving sound sources. PMID:25565971

Koka, Kanthaiah; Tollin, Daniel J.

2014-01-01

235

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

236

Complex degree of mutual anisotropy of linear birefringence and optical activity of biological tissues in diagnostics of prostate cancer  

NASA Astrophysics Data System (ADS)

We present theoretical fundamentals of polarization and correlation analysis of the optical anisotropy of biological tissues. Results of measurements of coordinate distributions of the complex degree of mutual anisotropy (CDMA) that are formed by birefringent structures of the prostate tissue with benign and malignant changes are compared. Magnitudes and ranges of variation of statistical (the firstto fourth-order distribution moments) and correlation (excess of autocorrelation functions) parameters of the coordinate CDMA distributions of histological sections of the prostate postoperative bioptic material are studied. Objective criteria of the diagnostics of the appearance of pathology and of the differentiation of the degree of its severity are determined.

Ushenko, V. A.; Gorsky, M. P.

2013-08-01

237

Secure Linear Algebra Using Linearly Recurrent Sequences Eike Kiltz , Payman Mohassel , Enav Weinreb , and Matthew Franklin  

E-print Network

Secure Linear Algebra Using Linearly Recurrent Sequences Eike Kiltz , Payman Mohassel , Enav core problems in linear algebra. Our main result is a protocol to obliviously decide singularity with low round and communication complexity). Keywords. Secure Linear Algebra, Linearly Recurrent Sequences

Mohassel, Payman

238

Reversible switching between nonquenched and quenched states in nanoscale linear arrays of plant light-harvesting antenna complexes.  

PubMed

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

Vasilev, Cvetelin; Johnson, Matthew P; Gonzales, Edward; Wang, Lin; Ruban, Alexander V; Montano, Gabriel; Cadby, Ashley J; Hunter, C Neil

2014-07-22

239

Linear {NiII-LnIII-NiII} complexes containing twisted planar Ni(?-phenolate)2 Ln fragments: synthesis, structure, and magnetothermal properties.  

PubMed

Sequential reaction of a multisite LH(4) ligand {2-[2-hydroxy-3-(hydroxymethyl)-5-methylbenzylideneamino]-2-methylpropane-1,3-diol} with appropriate lanthanide salts followed by the addition of Ni(NO(3))(2)?6?H(2)O in a 4:1:2 stoichiometric ratio in the presence of triethylamine afforded four heterobimetallic trinuclear complexes [Ni(2)Gd(LH(3))(4)]?3NO(3)?3?MeOH?H(2)O?CH(3)CN (1), [Ni(2)Tb(LH(3))(4)]?(3?)NO(3)?3?MeOH?CH(3)CN (2), [Ni(2)Dy(LH(3))(4)]?3?NO(3)?3?MeOH?H(2)O?CH(3)CN (3), and [Ni(2)Ho(LH(3))(4)]?3?NO(3)?3?MeOH?H(2)O?CH(3)CN (4). Complexes 1-4 possess linear trimetallic cores with a central lanthanide ion. Magnetic studies revealed a predominant ferromagnetic interaction between the Ni and Ln centers. Alternating current susceptibility measurements of complex 3 showed a small frequency dependence of the out-of-phase signal, ?''(M), under zero direct current field, but without achieving a net maximum above 2?K. Magnetic studies on 1 revealed that it has a significant magnetocaloric effect. PMID:24817615

Das, Sourav; Dey, Atanu; Kundu, Subrata; Biswas, Sourav; Mota, A J; Colacio, Enrique; Chandrasekhar, Vadapalli

2014-07-01

240

The Madison Symmetric Torus  

SciTech Connect

The Madison Symmetric Torus (MST) is the newest and largest reversed field pinch presently in operation. It incorporates a number of design features that set it apart from other pinches, including the use of the conducting shell as both a vacuum vessel and single-turn toroidal field coil. Specially insulated voltage gaps are exposed to the plasma. Magnetic field errors at these gaps as well as at the various diagnostic and pumping ports are minimized through a variety of techniques. The physics goals of MST include study of the effect of large plasma size on confinement and the investigation, in detail, of RFP turbulence, dynamo and transport. Details of the design and initial operation of the device are presented.

Dexter, R.N.; Kerst, D.W.; Lovell, T.W.; Prager, S.C.; Sprott, J.C.

1990-03-01

241

Forecasting Transitions in Systems with High-Dimensional Stochastic Complex Dynamics: A Linear Stability Analysis of the Tangled Nature Model  

NASA Astrophysics Data System (ADS)

We propose a new procedure to monitor and forecast the onset of transitions in high-dimensional complex systems. We describe our procedure by an application to the tangled nature model of evolutionary ecology. The quasistable configurations of the full stochastic dynamics are taken as input for a stability analysis by means of the deterministic mean-field equations. Numerical analysis of the high-dimensional stability matrix allows us to identify unstable directions associated with eigenvalues with a positive real part. The overlap of the instantaneous configuration vector of the full stochastic system with the eigenvectors of the unstable directions of the deterministic mean-field approximation is found to be a good early warning of the transitions occurring intermittently.

Cairoli, Andrea; Piovani, Duccio; Jensen, Henrik Jeldtoft

2014-12-01

242

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

243

Weyl symmetric structure of QCD vacuum  

E-print Network

We consider Weyl symmetric structure of the classical vacuum in quantum chromodynamics. In the framework of formalism of gauge invariant Abelian projection we show that classical vacuums can be constructed in terms of Killing vector fields on the group SU(3). Consequently, homotopic classes of Killing vector fields determine the topological structure of the vacuum. In particular, the second homotopy group \\pi_2(SU(3)/U(1)\\times U(1)) describes all topologically non-equivalent vacuums which are classified by two topological numbers. For each given Killing vector field one can construct six vacuums forming Weyl sextet representation. An interesting feature of SU(3) gauge theory is that it admits a Weyl symmetric vacuum represented by a linear superposition of the six vacuums from the Weyl vacuum sextet. A non-trivial manifestation of Weyl symmetry is demonstrated on monopole solutions. We construct a family of finite energy monopole solutions in Yang-Mills-Higgs theory which includes Weyl monopole sextet. From the analysis of the classical vacuum structure and monopole solutions we conjecture that a similar Weyl symmetric vacuum structure can be realized in quantum theory.

Y. M. Cho; D. G. Pak; P. M. Zhang; L. P. Zou

2012-09-12

244

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

245

Pyramid diffraction in parity-time-symmetric optical lattices  

E-print Network

Pyramid diffraction in parity-time-symmetric optical lattices Sean Nixon and Jianke Yang diffraction pattern is demonstrated in both the linear and nonlinear regimes. Blow-up is also possible oscillation, unidirectional propagation, distinct pattern of diffraction, formation of solitons and breath

Yang, Jianke

246

Self-calibration of a general radially symmetric distortion model  

E-print Network

Self-calibration of a general radially symmetric distortion model Jean-Philippe Tardif1 , Peter make use of the pin-hole camera model. One benefit of such a model is the linearity of the projection lines in the scene are not in general projected onto straight lines in the image, contrary to pin

Tardif, Jean-Philippe

247

Self-calibration of a general radially symmetric distortion model  

E-print Network

Self-calibration of a general radially symmetric distortion model Jean-Philippe Tardif1 , Peter make use of the pin-hole camera model. One benefit of such a model is the linearity of the projection, contrary to pin-hole cameras. Many calibration algorithms can deal with distortion, but they are usually

Paris-Sud XI, Université de

248

Extension of primal-dual interior point methods to diff-convex problems on symmetric cones  

Microsoft Academic Search

We consider the extension of primal dual interior point methods for linear programming on symmetric cones, to a wider class of problems that includes approximate necessary optimality conditions for functions expressible as the difference of two convex functions of a special form. Our analysis applies the Jordan-algebraic approach to symmetric cones. As the basic method is local, we apply the

Tuomo Valkonen

2011-01-01

249

THE SNAP-BACK PIVOTING METHOD FOR SYMMETRIC BANDED INDEFINITE MATRICES  

E-print Network

THE SNAP-BACK PIVOTING METHOD FOR SYMMETRIC BANDED INDEFINITE MATRICES DROR IRONY AND SIVAN TOLEDO for linear-equation solvers. We propose a new pivoting method, which we call snap-back pivoting. When applied symmetric (unlike any previous method), and it is fast. In snap-back pivoting, if the next diagonal element

Toledo, Sivan

250

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

251

Molecular properties of a bis(ketoiminato)-bis(tricarbonyliron) complex obtained by symmetric cleavage from acetophenone azine. Idealized symmetry in anti and syn isomers studied by X-ray diffraction, NMR and density functional theory  

NASA Astrophysics Data System (ADS)

Distinct anti and syn isomers of the bis(? 2-acetophenoniminato)-bis(tricarbonyliron) obtained from iron dodecacarbonyl and 1,4-dimethyl-1,4-diphenyl-2,3-diazabuta-1,3-diene by symmetric cleavage of the azine have been compared in terms of molecular deviations from symmetry. The study was carried out by the analysis of intra- and intermolecular close contacts in crystals, quantum chemical DFT calculations for the isolated molecules and by NMR in solution. In the crystalline state the intramolecular contacts and also the symmetry perturbations were more strongly expressed in the syn form as compared with anti, and the same relation was perceived in the DFT-optimized single molecules. However, in solution only symmetric conformations were observed for both isomers anti and syn by 1H and 13C NMR at room temperature and at -70°C.

Zimniak, Andrzej; Bakalarski, Grzegorz

2001-10-01

252

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

253

Nonlinear localized modes in PT-symmetric optical media with competing gain and loss  

SciTech Connect

The existence and stability of the nonlinear spatial localized modes are investigated in parity-time symmetric optical media characterized by a generic complex hyperbolic refractive index distribution with competing gain and loss profile. The exact analytical expression of the localized modes are found for all values of the competing parameter and in the presence of both the self-focusing and self-defocusing Kerr nonlinearity. The effects of competing gain/loss profile on the stability structure of these localized modes are discussed with the help of linear stability analysis followed by the direct numerical simulation of the governing equation. The spatial localized modes in two-dimensional geometry as well as the transverse power-flow density associated with these localized modes are also examined. -- Highlights: • Existence of localized modes is investigated in PT-symmetric complex potentials. • Exact analytical expression of the localized modes is obtained. • Effect of gain/loss profile on the stability of these localized modes is discussed. • Localized modes in 2D and associated transverse power-flow density are also examined.

Midya, Bikashkali, E-mail: bikash.midya@gmail.com [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700108 (India)] [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata 700108 (India); Roychoudhury, Rajkumar, E-mail: rroychoudhury123@gmail.com [Advanced Center for Nonlinear and Complex Phenomena, Kolkata 700075 (India)] [Advanced Center for Nonlinear and Complex Phenomena, Kolkata 700075 (India)

2014-02-15

254

Mutations in NDUFB11, Encoding a Complex I Component of the Mitochondrial Respiratory Chain, Cause Microphthalmia with Linear Skin Defects Syndrome.  

PubMed

Microphthalmia with linear skin defects (MLS) syndrome is an X-linked male-lethal disorder also known as MIDAS (microphthalmia, dermal aplasia, and sclerocornea). Additional clinical features include neurological and cardiac abnormalities. MLS syndrome is genetically heterogeneous given that heterozygous mutations in HCCS or COX7B have been identified in MLS-affected females. Both genes encode proteins involved in the structure and function of complexes III and IV, which form the terminal segment of the mitochondrial respiratory chain (MRC). However, not all individuals with MLS syndrome carry a mutation in either HCCS or COX7B. The majority of MLS-affected females have severe skewing of X chromosome inactivation, suggesting that mutations in HCCS, COX7B, and other as-yet-unidentified X-linked gene(s) cause selective loss of cells in which the mutated X chromosome is active. By applying whole-exome sequencing and filtering for X-chromosomal variants, we identified a de novo nonsense mutation in NDUFB11 (Xp11.23) in one female individual and a heterozygous 1-bp deletion in a second individual, her asymptomatic mother, and an affected aborted fetus of the subject's mother. NDUFB11 encodes one of 30 poorly characterized supernumerary subunits of NADH:ubiquinone oxidoreductase, known as complex I (cI), the first and largest enzyme of the MRC. By shRNA-mediated NDUFB11 knockdown in HeLa cells, we demonstrate that NDUFB11 is essential for cI assembly and activity as well as cell growth and survival. These results demonstrate that X-linked genetic defects leading to the complete inactivation of complex I, III, or IV underlie MLS syndrome. Our data reveal an unexpected role of cI dysfunction in a developmental phenotype, further underscoring the existence of a group of mitochondrial diseases associated with neurocutaneous manifestations. PMID:25772934

van Rahden, Vanessa A; Fernandez-Vizarra, Erika; Alawi, Malik; Brand, Kristina; Fellmann, Florence; Horn, Denise; Zeviani, Massimo; Kutsche, Kerstin

2015-04-01

255

Achromatic axially symmetric wave plate.  

PubMed

An achromatic axially symmetric wave plate (AAS-WP) is proposed that is based on Fresnel reflections. The wave plate does not introduce spatial dispersion. It provides retardation in the wavelength domain with an axially symmetric azimuthal angle. The optical configuration, a numerical simulation, and the optical properties of the AAS-WP are described. It is composed of PMMA. A pair of them is manufactured on a lathe. In the numerical simulation, the achromatic angle is estimated and is used to design the devices. They generate an axially symmetric polarized beam. The birefringence distribution is measured in order to evaluate the AAS-WPs. PMID:23388751

Wakayama, Toshitaka; Komaki, Kazuki; Otani, Yukitoshi; Yoshizawa, Toru

2012-12-31

256

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

257

A symmetric block-matching framework for global registration  

NASA Astrophysics Data System (ADS)

Most registration algorithms suffer from a directionality bias that has been shown to largely impact on subsequent analyses. Several approaches have been proposed in the literature to address this bias in the context of non-linear registration but little work has been done in the context of global registration. We propose a symmetric approach based on a block-matching technique and least trimmed square regression. The proposed method is suitable for multi-modal registration and is robust to outliers in the input images. The symmetric framework is compared to the original asymmetric block-matching technique, outperforming it in terms accuracy and robustness.

Modat, Marc; Cash, David M.; Daga, Pankaj; Winston, Gawin P.; Duncan, John S.; Ourselin, Sébastien

2014-03-01

258

Extension of PT-symmetric quantum mechanics to the Dirac theory with position-dependent mass  

SciTech Connect

We present a new method to construct the exactly solvable PT-symmetric potentials within the framework of the position-dependent effective mass Dirac equation with the vector potential coupling scheme in 1 + 1 dimensions. In order to illustrate the procedure, we produce three PT-symmetric potentials as examples, which are PT-symmetric harmonic oscillator-like potential, PT-symmetric potential with the form of a linear potential plus an inversely linear potential, and PT-symmetric kink-like potential, respectively. The real relativistic energy levels and corresponding spinor components for the bound states are obtained by using the basic concepts of the supersymmetric quantum mechanics formalism and function analysis method.

Jia Chunsheng [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500 (China)], E-mail: chshjia@263.net; Souza Dutra, A. de [UNESP-Campus de Guaratingueta-DFQ, Av. Dr. Ariberto Pereira da Cunha, 333 C.P. 205, 12516-410 Guaratingueta, SP (Brazil)], E-mail: dutra@feg.unesp.br

2008-03-15

259

Symmetric and triangle-shaped variability of blazars  

NASA Astrophysics Data System (ADS)

Symmetric and triangle-shaped flux variability in X-ray and gamma-ray light curves is observed from many blazars. We derived the X-ray spectrum changing in time by using a kinetic equation of high energy electrons. Giving linearly changing the injection of low energy electrons into accelerating and emitting region, we obtained the preliminary results that represent the characteristic X-ray variability of the linear flux increase with hardening in the rise phase and the linear decrease with softening in the decay phase.

Yoshida, Kenji

2015-03-01

260

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

261

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

262

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

263

Staggered parity-time-symmetric ladders with cubic nonlinearity  

NASA Astrophysics Data System (ADS)

We introduce a ladder-shaped chain with each rung carrying a parity-time- (PT -) symmetric gain-loss dimer. The polarity of the dimers is staggered along the chain, meaning alternation of gain-loss and loss-gain rungs. This structure, which can be implemented as an optical waveguide array, is the simplest one which renders the system PT -symmetric in both horizontal and vertical directions. The system is governed by a pair of linearly coupled discrete nonlinear Schrödinger equations with self-focusing or defocusing cubic onsite nonlinearity. Starting from the analytically tractable anticontinuum limit of uncoupled rungs and using the Newton's method for continuation of the solutions with the increase of the inter-rung coupling, we construct families of PT -symmetric discrete solitons and identify their stability regions. Waveforms stemming from a single excited rung and double ones are identified. Dynamics of unstable solitons is investigated too.

D'Ambroise, Jennie; Kevrekidis, P. G.; Malomed, Boris A.

2015-03-01

264

Integrability and Vesture for Axially Symmetric Harmonic Maps  

NASA Astrophysics Data System (ADS)

We investigate the interrelationship between integrability, inverse-scattering (ISM), and vesture for harmonic maps into symmetric spaces. Motivated by the application of ISM to the Einstein Equations in the case of stationary, axisymmetric metrics, we show that the equations for an axially symmetric harmonic map of R3 into a symmetric space G/K are completely integrable. Furthermore, new solutions for these equations can be generated starting from a given seed solution. As an application to General Relativity, we consider the problem of finding N-solitonic harmonic maps into the noncompact Grassmann manifolds SU(p, q)/S(U(p) × U(q)) and find it is completely reducible via dressing to a problem in linear algebra. We indicate directions for further investigation.

Beheshti, Shabnam; Tahvildar-Zadeh, Shadi

2015-01-01

265

Jack-Laurent symmetric functions for special values of parameters  

E-print Network

We consider the Jack--Laurent symmetric functions for special values of parameters p_0=n+k^{-1}m, where k is not rational and m and n are natural numbers. In general, the coefficients of such functions may have poles at these values of p_0. The action of the corresponding algebra of quantum Calogero-Moser integrals D(k,p_0) on the space of Laurent symmetric functions defines the decomposition into generalised eigenspaces. We construct a basis in each generalised eigenspace as certain linear combinations of the Jack--Laurent symmetric functions, which are regular at p_0=n+k^{-1}m, and describe the action of D(k,p_0) in these eigenspaces.

A. N. Sergeev; A. P. Veselov

2014-12-29

266

SymmRef: a Flexible Refinement Method for Symmetric Multimers  

PubMed Central

Symmetric protein complexes are abundant in the living cell. Predicting their atomic structure can shed light on the mechanism of many important biological processes. Symmetric docking methods aim to predict the structure of these complexes given the unbound structure of a single monomer, or its model. Symmetry constraints reduce the search-space of these methods and make the prediction easier compared to asymmetric protein-protein docking. However the challenge of modeling the conformational changes that the monomer might undergo is a major obstacle. In this paper we present SymmRef, a novel method for refinement and re-ranking of symmetric docking solutions. The method models backbone and side-chain movements and optimizes the rigid-body orientations of the monomers. The backbone movements are modeled by normal modes minimization and the conformations of the side-chains are modeled by selecting optimal rotamers. Since solved structures of symmetric multimers show asymmetric side-chain conformations, we do not use symmetry constraints in the side-chain optimization procedure. The refined models are re-ranked according to an energy score. We tested the method on a benchmark of unbound docking challenges. The results show that the method significantly improves the accuracy and the ranking of symmetric rigid docking solutions. SymmRef is available for download at http://bioinfo3d.cs.tau.ac.il/SymmRef/download.html. PMID:21721046

Mashiach-Farkash, Efrat; Nussinov, Ruth; Wolfson, Haim J.

2011-01-01

267

Transformations between symmetric sets of quantum states  

E-print Network

We investigate probabilistic transformations of quantum states from a `source' set to a `target' set of states. Such transforms have many applications. They can be used for tasks which include state-dependent cloning or quantum state discrimination, and as interfaces between systems whose information encodings are not related by a unitary transform, such as continuous-variable systems and finite-dimensional systems. In a probabilistic transform, information may be lost or leaked, and we explain the concepts of leak and redundancy. Following this, we show how the analysis of probabilistic transforms significantly simplifies for symmetric source and target sets of states. In particular, we give a simple linear program which solves the task of finding optimal transforms, and a method of characterizing the introduced leak and redundancy in information-theoretic terms. Using the developed techniques, we analyse a class of transforms which convert coherent states with information encoded in their relative phase to symmetric qubit states. Each of these sets of states on their own appears in many well studied quantum information protocols. Finally, we suggest an asymptotic realization based on quantum scissors.

Vedran Dunjko; Erika Andersson

2012-06-22

268

Integrable deformations of strings on symmetric spaces  

NASA Astrophysics Data System (ADS)

A general class of deformations of integrable sigma-models with symmetric space F/G target-spaces are found. These deformations involve defining the non-abelian T dual of the sigma-model and then replacing the coupling of the Lagrange multiplier imposing flatness with a gauged F/F WZW model. The original sigma-model is obtained in the limit of large level. The resulting deformed theories are shown to preserve both integrability and the equations-of-motion, but involve a deformation of the symplectic structure. It is shown that this deformed symplectic structure involves a linear combination of the original Poisson bracket and a generalization of the Faddeev-Reshetikhin Poisson bracket which we show can be re-expressed as two decoupled F current algebras. It is then shown that the deformation can be incorporated into the classical model of strings on via a generalization of the Pohlmeyer reduction. In this case, in the limit of large sigma-model coupling it is shown that the theory becomes the relativistic symmetric space sine-Gordon theory. These results point to the existence of a deformation of this kind for the full Green-Schwarz superstring on AdS5 × S 5.

Hollowood, Timothy J.; Miramontes, J. Luis; Schmidtt, David M.

2014-11-01

269

Some New Results for Linear Transformations on Euclidean Jordan Algebras  

NASA Astrophysics Data System (ADS)

Generalizing the w-P property of a matrix, Tao [Some w-P properties for linear transformations on Euclidean Jordan algebras, to appear in Pacific J. Optimization] recently introduced and studied the w-P and the w-uniqueness properties for linear transformations defined on Euclidean Jordan algebras. In this paper, we study further to these properties. In particular, we specialize them to the space Sn of all n×n real symmetric matrices and the space Hn of all n n complex Hermitian matrices for Lyapunov and Stein transformations. We also present a sufficient condition for the w-uniqueness property on Sn. In addition, we give a characterization of the w-P and the column sufficiency properties for a matrix-induced transformation on Euclidean Jordan algebras.

Tao, Jiyuan

2009-09-01

270

Hamiltonian theory of symmetric optical network transforms  

NASA Astrophysics Data System (ADS)

We discuss the theory of extracting an interaction Hamiltonian from a preassigned unitary transformation of quantum states. Such a procedure is of significance in quantum computations and other optical information processing tasks. We particularize the problem to the construction of totally symmetric 2N ports as introduced by Zeilinger and his collaborators [A. Zeilinger, M. Zukowski, M. A. Horne, H. J. Bernstein, and D. M. Greenberger, in Fundamental Aspects of Quantum Theory, edited by J. Anandan and J. J. Safko (World Scientific, Singapore, 1994)]. These are realized by the discrete Fourier transform, which simplifies the construction of the Hamiltonian by known methods of linear algebra. The Hamiltonians found are discussed and alternative realizations of the Zeilinger class transformations are presented. We briefly discuss the applicability of the method to more general devices.

Törmä, Päivi; Stenholm, Stig

1995-12-01

271

Bunch-Kaufman factorization for real symmetric indefinite banded matrices  

NASA Technical Reports Server (NTRS)

The Bunch-Kaufman algorithm for factoring symmetric indefinite matrices was rejected for banded matrices because it destroys the banded structure of the matrix. Herein, it is shown that for a subclass of real symmetric matrices which arise in solving the generalized eigenvalue problem using Lanczos's method, the Bunch-Kaufman algorithm does not result in major destruction of the bandwidth. Space time complexities of the algorithm are given and used to show that the Bunch-Kaufman algorithm is a significant improvement over LU factorization.

Jones, Mark T.; Patrick, Merrell L.

1989-01-01

272

Phi-symmetric effect algebras  

NASA Astrophysics Data System (ADS)

The notion of a Sasaki projection on an orthomodular lattice is generalized to a mapping ?: E × E ? E, where E is an effect algebra. If E is lattice ordered and ? is symmetric, then E is called a ?-symmetric effect algebra. This paper launches a study of such effect algebras. In particular, it is shown that every interval effect algebra with a lattice-ordered ambient group is ?-symmetric, and its group is the one constructed by Ravindran in his proof that every effect algebra that has the Riesz decomposition property is an interval algebra. It is shown that the doubling construction introduced in the paper is connected to the conditional event algebras of Goodman, Nguyen, and Walker.

Bennett, M. K.; Foulis, D. J.

1995-12-01

273

Symmetric and antisymmetric nonlinear modes supported by dual local gain in lossy lattices  

NASA Astrophysics Data System (ADS)

We introduce a discrete lossy system, into which a double "hot spot" (HS) is inserted, i.e., two mutually symmetric sites carrying linear gain and cubic nonlinearity. The system can be implemented as an array of optical or plasmonic waveguides, with a pair of amplified nonlinear cores embedded into it. We focus on the case of self-defocusing nonlinearity and cubic losses acting at the HSs. Symmetric localized modes pinned to the double HS are constructed in an implicit analytical form, which is done separately for the cases of odd and even numbers of intermediate sites between the HSs. In the former case, some stationary solutions feature a W-like shape, with a low peak at the central site, added to tall peaks at the positions of the embedded HSs. The special case of two adjacent HSs is considered too. Stability of the solution families against small perturbations is investigated in a numerical form, which reveals stable and unstable subfamilies. The instability generated by an isolated positive eigenvalue leads to a spontaneous transformation into a co-existing stable antisymmetric mode, while a pair of complex-conjugate eigenvalues gives rise to persistent breathers. This article is a contribution to the volume dedicated to Professor Helmut Brand on the occasion of his 60th birhday.

Chow, K. W.; Ding, Edwin; Malomed, B. A.; Tang, A. Y. S.

2014-01-01

274

The Generalized Sidelobe Canceller Based on Quaternion Widely Linear Processing  

PubMed Central

We investigate the problem of quaternion beamforming based on widely linear processing. First, a quaternion model of linear symmetric array with two-component electromagnetic (EM) vector sensors is presented. Based on array's quaternion model, we propose the general expression of a quaternion semiwidely linear (QSWL) beamformer. Unlike the complex widely linear beamformer, the QSWL beamformer is based on the simultaneous operation on the quaternion vector, which is composed of two jointly proper complex vectors, and its involution counterpart. Second, we propose a useful implementation of QSWL beamformer, that is, QSWL generalized sidelobe canceller (GSC), and derive the simple expressions of the weight vectors. The QSWL GSC consists of two-stage beamformers. By designing the weight vectors of two-stage beamformers, the interference is completely canceled in the output of QSWL GSC and the desired signal is not distorted. We derive the array's gain expression and analyze the performance of the QSWL GSC in the presence of one type of interference. The advantage of QSWL GSC is that the main beam can always point to the desired signal's direction and the robustness to DOA mismatch is improved. Finally, simulations are used to verify the performance of the proposed QSWL GSC. PMID:24955425

Tao, Jian-wu; Chang, Wen-xiu

2014-01-01

275

Pyramid diffraction in parity-time-symmetric optical lattices  

E-print Network

Nonlinear dynamics of wave packets in two-dimensional parity-time-symmetric optical lattices near the phase-transition point are analytically studied. A novel fourth-order equation is derived for the envelope of these wave packets. A pyramid diffraction pattern is demonstrated in both the linear and nonlinear regimes. Blow-up is also possible in the nonlinear regime for both focusing and defocusing nonlinearities.

Nixon, Sean

2013-01-01

276

Canonical distributions on Riemannian homogeneous k-symmetric spaces  

NASA Astrophysics Data System (ADS)

It is known that distributions generated by almost product structures are applicable, in particular, to some problems in the theory of Monge-Ampère equations. In this paper, we characterize canonical distributions defined by canonical almost product structures on Riemannian homogeneous k-symmetric spaces in the sense of types AF (anti-foliation), F (foliation), TGF (totally geodesic foliation). Algebraic criteria for all these types on k-symmetric spaces of orders k = 4 , 5 , 6 were obtained. Note that canonical distributions on homogeneous k-symmetric spaces are closely related to special canonical almost complex structures and f-structures, which were recently applied by I. Khemar to studying elliptic integrable systems.

Balashchenko, Vitaly V.

2015-01-01

277

{PT}-symmetrically deformed shock waves  

NASA Astrophysics Data System (ADS)

We investigate for a large class of nonlinear wave equations, which allow for shock wave formations, how these solutions behave when they are {PT}-symmetrically deformed. For real solutions we find that they are transformed into peaked solutions with a discontinuity in the first derivative instead. The systems we investigate include the {PT}-symmetrically deformed inviscid Burgers equation recently studied by Bender and Feinberg, for which we show that it does not develop any shocks, but peaks instead. In this case we exploit the rare fact that the {PT}-deformation can be provided by an explicit map found by Curtright and Fairlie together with the property that the undeformed equation can be solved by the method of characteristics. We generalise the map and observe this type of behaviour for all integer values of the deformation parameter ?. The peaks are formed as a result of mapping the multi-valued self-avoiding shock profile to a multi-valued self-crossing function by means of the {PT}-deformation. For some deformation parameters we also investigate the deformation of complex solutions and demonstrate that in this case the deformation mechanism leads to discontinuities. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.

Cavaglia, Andrea; Fring, Andreas

2012-11-01

278

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

279

Synthesis of a symmetrical dithiirane  

SciTech Connect

The reaction of p-xylene with epichlorohydrin in the presence of aluminum chloride gave 1,4-dimethyl-2,5-bis(1-chloro-2-hydroxypropyl) benzene, which serves as the starting compound for the synthesis of the corresponding symmetrical dithiirane.

Allakverdiev, M.A.; Farzaliev, V.M.; Mamedov, C.I.

1986-04-01

280

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

281

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

282

Copper and iron complexes of linear and crosslinked polymers as catalysts for phosphoester hydrolysis and oxidative transformation of phenolic and catecholic substrates  

Microsoft Academic Search

The goal of this study is to utilize polymers as macromolecular ligands for the construction of catalysts by formation of coordination complexes with transition metals with the main focus on complexes of Cu(II) and Fe(III) and further determine (a) their catalytic efficiency (b) mechanism of action (c) similarities to enzymatic systems and synthetic metal complexes. The reactions of interest are

Vasiliki Lykourinou

2006-01-01

283

Tunable Band-Stop Plasmonic Filter Based on Symmetrical Tooth-Shaped Waveguide Couples  

NASA Astrophysics Data System (ADS)

A simple plasmonic filter with symmetrical tooth-shaped waveguides is proposed and investigated by using finite element method. It is found that the structure with a single symmetrical tooth-shaped waveguide couple can realize a tunable band-stop filter. Attributed to cascaded symmetrical tooth-shaped waveguide couples, the structure can achieve a flat band-stop response with no intensity variation over the transmission spectrum. And the central wavelength of the stopband linearly increases with the simultaneous increasing of depths of waveguides. Moreover, reduced structure size can be achieved by controlling the dielectric constant of the medium.

Cui, Luna; Song, Gang; Yu, Li; Lang, Peiling; Xiao, Jinghua

2013-06-01

284

DNA Security using Symmetric and Asymmetric Cryptography  

Microsoft Academic Search

This paper presents alternative security methods based on DNA. From the available alternative security methods, symmetric DNA algorithms were developed and implemented. The first symmetric DNA algorithm was implemented in the Java language, while the second DNA algorithm was implemented in BioJava and MatLab. Comparisons have been made between the performances of different standard symmetrical algorithms and the DNA proposed

Radu Terec; MirceaFlorin Vaida; Lenuta Alboaie; Ligia Chiorean

285

DNA Security using Symmetric and Asymmetric Cryptography  

Microsoft Academic Search

This paper presents alternative security methods based on DNA. From the available alternative security methods, symmetric DNA algorithms were developed and implemented. The first symmetric DNA algorithm was implemented in the Java language, while the second DNA algorithm was implemented in BioJava and MatLab. Comparisons have been made between the performances of different standard symmetrical algorithms and the DNA proposed

L. Alboaie L. Chiorean M. Vaida Radu Terec

2011-01-01

286

Perturbation theory of PT-symmetric Hamiltonians  

E-print Network

In the framework of perturbation theory the reality of the perturbed eigenvalues of a class of $\\PT$symmetric Hamiltonians is proved using stability techniques. We apply this method to $\\PT$symmetric unperturbed Hamiltonians perturbed by $\\PT$symmetric additional interactions.

E. Caliceti; F. Cannata; S. Graffi

2006-07-19

287

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

2014-08-01

288

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

289

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

290

Centralisers of spaces of symmetric tensor products and applications  

Microsoft Academic Search

We show that the centraliser of the space of n-fold symmetric injective tensors, n?2, on a real Banach space is trivial. With a geometric condition on the set of extreme points of its dual, the space of integral\\u000a polynomials we obtain the same result for complex Banach spaces. We give some applications of this results to centralisers\\u000a of spaces of

Christopher Boyd; Silvia Lassalle

2006-01-01

291

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)=g(2)(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

292

A polypeptide "building block" for the ?-trefoil fold identified by "top-down symmetric deconstruction".  

PubMed

Fibroblast growth factor-1, a member of the 3-fold symmetric ?-trefoil fold, was subjected to a series of symmetric constraint mutations in a process termed "top-down symmetric deconstruction." The mutations enforced a cumulative exact 3-fold symmetry upon symmetrically equivalent positions within the protein and were combined with a stability screen. This process culminated in a ?-trefoil protein with exact 3-fold primary-structure symmetry that exhibited excellent folding and stability properties. Subsequent fragmentation of the repeating primary-structure motif yielded a 42-residue polypeptide capable of spontaneous assembly as a homotrimer, producing a thermostable ?-trefoil architecture. The results show that despite pronounced reduction in sequence complexity, pure symmetry in the design of a foldable, thermostable ?-trefoil fold is possible. The top-down symmetric deconstruction approach provides a novel alternative means to successfully identify a useful polypeptide "building block" for subsequent "bottom-up" de novo design of target protein architecture. PMID:21315087

Lee, Jihun; Blaber, Sachiko I; Dubey, Vikash K; Blaber, Michael

2011-04-15

293

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; André, Ingemar

2011-01-01

294

A Levinson-like algorithm for symmetric strongly nonsingular higher order semiseparable plus band matrices  

NASA Astrophysics Data System (ADS)

In this paper, we will derive a solver for a symmetric strongly nonsingular higher order generator representable semiseparable plus band matrix. The solver we will derive is based on the Levinson algorithm, which is used for solving strongly nonsingular Toeplitz systems. In the first part an O(p2n) solver for a semiseparable matrix of semiseparability rank p is derived, and in a second part we derive an O(l2n) solver for a band matrix with bandwidth 2l+1. Both solvers are constructed in a similar way: firstly a Yule-Walker-like equation needs to be solved, and secondly this solution is used for solving a linear equation with an arbitrary right-hand side. Finally, a combination of the above methods is presented to solve linear systems with semiseparable plus band coefficient matrices. The overall complexity of this solver is 6(l+p)2n plus lower order terms. In the final section numerical experiments are performed. Attention is paid to the timing and the accuracy of the described methods.

Vandebril, Raf; Mastronardi, Nicola; van Barel, Marc

2007-01-01

295

Exchange interactions and zero-field splittings in C3-symmetric Mn(III)6Fe(III): using molecular recognition for the construction of a series of high spin complexes based on the triplesalen ligand.  

PubMed

The reaction of the tris(tetradentate) triplesalen ligand H6talen(t-Bu2), which provides three salen-like coordination environments bridged in a meta-phenylene arrangement by a phloroglucinol backbone, with Mn(II) salts under aerobic conditions affords, in situ, the trinuclear Mn(III) triplesalen complexes [(talen(t-Bu2)){Mn(III)(solv)n}3]3+. These can be used as molecular building blocks in the reaction with [Fe(CN)6]3- as a hexaconnector to form the heptanuclear complex [{(talen(t-Bu2)){Mn(III)(solv)n}3}2{Fe(III)(CN)6}]3+ ([Mn(III)6Fe(III)]3+). The regular ligand folding observed in the trinuclear triplesalen complexes preorganizes the three metal ions for the reaction of three facially coordinated nitrogen atoms of a hexacyanometallate and provides a driving force for the formation of the heptanuclear complexes [M(t)6M(c)]n+ (M(t), terminal metal ion of the triplesalen building block; M(c), central metal ion of the hexacyanometallate) by molecular recognition, as has already been demonstrated for the single-molecule magnet [Mn(III)6Cr(III)]3+. [{(talen(t-Bu2))(Mn(III)(MeOH))3}2{Fe(III)(CN)6}][Fe(III)(CN)6] (1) was characterized by single-crystal X-ray diffraction, FTIR, ESI- and MALDI-TOF-MS, Mössbauer spectroscopy, and magnetic measurements. The molecular structure of [Mn(III)6Fe(III)]3+ is overall identical to that of [Mn(III)6Cr(III)]3+ but exhibits a different ligand folding of the Mn(III) salen subunits with a helical distortion. The Mössbauer spectra demonstrate a stronger distortion from octahedral symmetry for the central [Fe(CN)6]3- in comparison to the ionic [Fe(CN)6]3-. At low temperatures in zero magnetic fields, the Mössbauer spectra show magnetic splittings indicative of slow relaxation of the magnetization on the Mössbauer time scale. Variable-temperature-variable-field and mu(eff) versus T magnetic data have been analyzed in detail by full-matrix diagonalization of the appropriate spin-Hamiltonian, consisting of isotropic exchange, zero-field splitting, and Zeeman interaction taking into account the relative orientation of the D tensors. Satisfactory reproduction of the experimental data has been obtained for parameters sets J(Mn-Mn) = -(0.85 +/- 0.15) cm(-1), J(Fe-Mn) = +(0.70 +/- 0.30) cm(-1), and D(Mn) = -(3.0 +/- 0.7) cm(-1). Comparing these values to those of [Mn(III)6Cr(III)]3+ provides insight into why [Mn(III)6Fe(III)]3+ is not a single-molecule magnet. PMID:19072685

Glaser, Thorsten; Heidemeier, Maik; Krickemeyer, Erich; Bögge, Hartmut; Stammler, Anja; Fröhlich, Roland; Bill, Eckhard; Schnack, Jürgen

2009-01-19

296

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

297

Linear Accelerators  

SciTech Connect

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 [Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna (Russian Federation)

2010-01-05

298

Critical binding and electron scattering by symmetric-top polar molecules  

SciTech Connect

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.

Garrett, W. R., E-mail: wrg@utk.edu [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States)

2014-10-28

299

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.

2010-07-30

300

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

301

Accuracy assessment of the linear Poisson-Boltzmann equation and reparametrization of the OBC generalized Born model for nucleic acids and nucleic acid-protein complexes.  

PubMed

The generalized Born model in the Onufriev, Bashford, and Case (Onufriev et al., Proteins: Struct Funct Genet 2004, 55, 383) implementation has emerged as one of the best compromises between accuracy and speed of computation. For simulations of nucleic acids, however, a number of issues should be addressed: (1) the generalized Born model is based on a linear model and the linearization of the reference Poisson-Boltmann equation may be questioned for highly charged systems as nucleic acids; (2) although much attention has been given to potentials, solvation forces could be much less sensitive to linearization than the potentials; and (3) the accuracy of the Onufriev-Bashford-Case (OBC) model for nucleic acids depends on fine tuning of parameters. Here, we show that the linearization of the Poisson Boltzmann equation has mild effects on computed forces, and that with optimal choice of the OBC model parameters, solvation forces, essential for molecular dynamics simulations, agree well with those computed using the reference Poisson-Boltzmann model. © 2015 Wiley Periodicals, Inc. PMID:25581160

Fogolari, Federico; Corazza, Alessandra; Esposito, Gennaro

2015-04-15

302

Matching method and exact solvability of discrete PT-symmetric square wells  

E-print Network

Discrete PT-symmetric square wells are studied. Their wave functions are found proportional to classical Tshebyshev polynomials of complex argument. The compact secular equations for energies are derived giving the real spectra in certain intervals of non-Hermiticity strengths Z. It is amusing to notice that although the known square well re-emerges in the usual continuum limit, a twice as rich, upside-down symmetric spectrum is exhibited by all its present discretized predecessors.

Miloslav Znojil

2006-05-24

303

Painleve Transcendents and PT-Symmetric Hamiltonians  

E-print Network

Unstable separatrix solutions for the first and second Painlev\\'e transcendents are studied both numerically and analytically. For a fixed initial condition, say $y(0)=0$, there is a discrete set of initial slopes $y'(0)=b_n$ that give rise to separatrix solutions. Similarly, for a fixed initial slope, say $y'(0)= 0$, there is a discrete set of initial values $y(0)=c_n$ that give rise to separatrix solutions. For Painlev\\'e I the large-$n$ asymptotic behavior of $b_n$ is $b_n\\sim B_{\\rm I}n^{3/5}$ and that of $c_n$ is $c_n\\sim C_{\\rm I}n^{2/ 5}$, and for Painlev\\'e II the large-$n$ asymptotic behavior of $b_n$ is $b_n \\sim B_{\\rm II}n^{2/3}$ and that of $c_n$ is $c_n\\sim C_{\\rm II}n^{1/3}$. The constants $B_{\\rm I}$, $C_{\\rm I}$, $B_{\\rm II}$, and $C_{\\rm II}$ are first determined numerically. Then, they are found analytically and in closed form by reducing the nonlinear equations to the linear eigenvalue problems associated with the cubic and quartic PT-symmetric Hamiltonians $H=\\frac{1}{2}p^2+2ix^3$ and $H=\\frac{1}{2}p^2-\\frac{1}{2}x^4$.

Carl M. Bender; Javad Komijani

2015-02-13

304

Boson sampling with displaced single-photon Fock states versus single-photon-added coherent states: The quantum-classical divide and computational-complexity transitions in linear optics  

NASA Astrophysics Data System (ADS)

Boson sampling is a specific quantum computation, which is likely hard to implement efficiently on a classical computer. The task is to sample the output photon-number distribution of a linear-optical interferometric network, which is fed with single-photon Fock-state inputs. A question that has been asked is if the sampling problems associated with any other input quantum states of light (other than the Fock states) to a linear-optical network and suitable output detection strategies are also of similar computational complexity as boson sampling. We consider the states that differ from the Fock states by a displacement operation, namely the displaced Fock states and the photon-added coherent states. It is easy to show that the sampling problem associated with displaced single-photon Fock states and a displaced photon-number detection scheme is in the same complexity class as boson sampling for all values of displacement. On the other hand, we show that the sampling problem associated with single-photon-added coherent states and the same displaced photon-number detection scheme demonstrates a computational-complexity transition. It transitions from being just as hard as boson sampling when the input coherent amplitudes are sufficiently small to a classically simulatable problem in the limit of large coherent amplitudes.

Seshadreesan, Kaushik P.; Olson, Jonathan P.; Motes, Keith R.; Rohde, Peter P.; Dowling, Jonathan P.

2015-02-01

305

Electronic Structure and Bonding in Transition Metal Inorganic and Organometallic Complexes: New Basis Sets, Linear Semibridging Carbonyls and Thiocarbonyls, and Oxidative Addition of Molecular Hydrogen to Square - Iridium Complexes  

Microsoft Academic Search

Approximate molecular orbital and ab initio quantum chemical techniques are used to investigate the electronic structure, bonding and reactivity of several transition metal inorganic and organometallic complexes. Modest-sized basis sets are developed for the second-row transition metal atoms and are designed for use in geometry optimizations of inorganic and organometallic complexes incorporating these atoms. The basis sets produce optimized equilibrium

Andrew Landman Sargent

1991-01-01

306

Competing {PT} potentials and the re-entrant {PT}-symmetric phase: a particle in a box  

NASA Astrophysics Data System (ADS)

We investigate the effects of competition between two complex, {PT}-symmetric potentials on the {PT}-symmetric phase of a ‘particle in a box’. These potentials, given by VZ(x) = iZsign(x) and V?(x) = i?[?(x - a) - ?(x + a)], represent long-range and localized gain/loss regions, respectively. We obtain the {PT}-symmetric phase in the (Z, ?) plane, and find that for locations ±a near the edge of the box, surprisingly, the {PT}-symmetric phase is strengthened by additional losses to the loss region. Consequently, we predict that a broken {PT}-symmetry will be restored by increasing the strength ? of the localized potential. By comparing the results for this problem and its lattice counterpart, we show that a robust {PT}-symmetric phase in the continuum is consistent with the fragile phase on the lattice. Our results demonstrate that systems with multiple, {PT}-symmetric potentials show unique, unexpected properties.

Joglekar, Yogesh N.; Bagchi, Bijan

2012-10-01

307

Linear Colliders  

NASA Astrophysics Data System (ADS)

An overview of linear collider programs is given. The history and technical challenges are described and the pioneering electron-positron linear collider, the SLC, is first introduced. For future energy frontier linear collider projects, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC) are introduced and their technical features are discussed. The ILC is based on superconducting RF technology and the CLIC is based on two-beam acceleration technology. The ILC collaboration completed the Technical Design Report in 2013, and has come to the stage of "Design to Reality." The CLIC collaboration published the Conceptual Design Report in 2012, and the key technology demonstration is in progress. The prospects for further advanced acceleration technology are briefly discussed for possible long-term future linear colliders.

Yamamoto, Akira; Yokoya, Kaoru

2015-02-01

308

Origin of symmetric PMNS and CKM matrices  

NASA Astrophysics Data System (ADS)

The Pontecorvo-Maki-Nakagawa-Sakata and Cabibbo-Kobayashi-Maskawa matrices are phenomenologically close to symmetric, and a symmetric form could be used as zeroth-order approximation for both matrices. We study the possible theoretical origin of this feature in flavor symmetry models. We identify necessary geometric properties of discrete flavor symmetry groups that can lead to symmetric mixing matrices. Those properties are actually very common in discrete groups such as A4 , S4 , or ? (96 ) . As an application of our theorem, we generate a symmetric lepton mixing scheme with ?12=?23=36.21 ° ; ?13=12.20 ° , and ? =0 , realized with the group ? (96 ) .

Rodejohann, Werner; Xu, Xun-Jie

2015-03-01

309

Partition Coefficients (Iog P) and HPLC Capacity Factors (k') of Some Gd(III) Complexes of Linear and Macrocyclic Polyamino Carboxylates  

Microsoft Academic Search

The partition coefficients (log P) in n-butanol\\/water and n-octanol\\/water together with the HPLC capacity factors (k') in 2% and 4% acetonitrile (ACN) and aqueous buffered mobile phase were determined for 21 Gd(III) chelates of linear and macrocyclic polyamino carboxylates. A C18 reversed-phase (Nucleosil) column was used for determination of k'. The log P values were calculated (clog P) for the

Krishan Kumar; K. Sukumaran; S. Taylor; C. Allen Chang; A. D. Nunn; M. F. Tweedle

1994-01-01

310

Metal ion complexes of. cap alpha. -amido acids. 2. Structure and magnetic properties of iron(II) hippurate, a linear-chain insulator  

Microsoft Academic Search

Iron(II) hippurate, Fe(hipp)â(HâO)â 2HâO, has been prepared and characterized. Single-crystal x-ray diffraction revealed the compound to be essentially isostructural with the previously reported cobalt(II) and nickel(II) hippurates, crystallizing as a linear chain with canted metal octahedra bridged by the oxygen atom of a water molecule. The space group is C2\\/c with four formula weights per unit cell. The structural properties

Maurice M. Morelock; Mary L. Good; Louis M. Trefonas; Richard. Majeste; David G. Karraker

1982-01-01

311

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

312

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

2006-06-07

313

Geometrodynamics in a spherically symmetric, static crossflow of null dust  

E-print Network

The spherically symmetric, static spacetime generated by a crossflow of non-interacting radiation streams, treated in the geometrical optics limit (null dust) is equivalent to an anisotropic fluid forming a radiation atmosphere of a star. This reference fluid provides a preferred / internal time, which is employed as a canonical coordinate. Among the advantages we encounter a new Hamiltonian constraint, which becomes linear in the momentum conjugate to the internal time (therefore yielding a functional Schr\\"{o}dinger equation after quantization), and a strongly commuting algebra of the new constraints.

Zsolt Horváth; Zoltán Kovács; László Á. Gergely

2006-10-12

314

Elementary Linear Algebra  

NSDL National Science Digital Library

This online textbook, Elementary Linear Algebra, is made available by Keith Matthews of the Department of Mathematics at the University of Queensland. Sections are organized into chapters such as Linear Equations, Matrices, Subspaces, Determinants, Complex Numbers, Eigenvalues and Eigenvectors, Identifying Second Degree Equations, and Three-dimensional Geometry. Each chapter features problems with the solutions available on-site. This is an excellent companion guide for college students taking linear algebra. In addition, the site includes an exact arithmetic matrix program, CMAT, that "performs exact calculations on matrices whose elements are rational numbers, complex rational numbers or numbers from a finite field of p (prime) elements." This program makes it easier to calculate problems such as the reduced row echelon form, the determinant, and the characteristic polynomial of a matrix.

Matthews, Keith R.

1991-01-01

315

Symmetry breaking of solitons in two-dimensional complex potentials  

NASA Astrophysics Data System (ADS)

Symmetry breaking is reported for continuous families of solitons in the nonlinear Schrödinger equation with a two-dimensional complex potential. This symmetry breaking is forbidden in generic complex potentials. However, for a special class of partially parity-time-symmetric potentials, it is allowed. At the bifurcation point, two branches of asymmetric solitons bifurcate out from the base branch of symmetry-unbroken solitons. Stability of these solitons near the bifurcation point are also studied, and two novel properties for the bifurcated asymmetric solitons are revealed. One is that at the bifurcation point, zero and simple imaginary linear-stability eigenvalues of asymmetric solitons can move directly into the complex plane and create oscillatory instability. The other is that the two bifurcated asymmetric solitons, even though having identical powers and being related to each other by spatial mirror reflection, can possess different types of unstable eigenvalues and thus exhibit nonreciprocal nonlinear evolutions under random-noise perturbations.

Yang, Jianke

2015-02-01

316

{\\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

317

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

318

Optimally smooth symmetric quadrature mirror filters for image coding  

NASA Astrophysics Data System (ADS)

Symmetric quadrature mirror filters (QMFs) offer several advantages for wavelet-based image coding. Symmetry and odd-length contribute to efficient boundary handling and preservation of edge detail. Symmetric QMFs can be obtained by mildly relaxing the filter bank orthogonality conditions. We describe a computational algorithm for these filter banks which is also symmetric in the sense that the analysis and synthesis operations have identical implementations, up to a delay. The essence of a wavelet transform is its multiresolution decomposition, obtained by iterating the lowpass filter. This allows one to introduce a new design criterion, smoothness (good behavior) of the lowpass filter under iteration. This design constraint can be expressed solely in terms of the lowpass filter tap values (via the eigenvalue decomposition of a certain finite-dimensional matrix). Our innovation is to design near- orthogonal QMFs with linear-phase symmetry which are optimized for smoothness under iteration, not for stopband rejection. The new class of optimally smooth QMF filter banks yields high performance in a practical image compression system.

Heller, Peter N.; Shapiro, Jerome M.; Wells, Raymond O., Jr.

1995-04-01

319

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

320

FULL NESTEROV-TODD STEP INTERIOR-POINT METHODS FOR SYMMETRIC OPTIMIZATION  

Microsoft Academic Search

Some Jordan algebras were proved more than a decade ago to be an indispensable tool in the unified study of interior-point methods. By using it, we generalize the infeasible interior- point method for linear optimization of Roos (SIAM J. Optim., 16(4):1110-1136 (electronic), 2006) to symmetric optimization. This unifies the analysis for linear, second-order cone and semidefinite optimizations.

G. GU; M. ZANGIABADI; C. ROOS

321

Identification of an S= {1}/{2} defect in linear trimer [Ni 3(dpa) 4Cl 2] complex by single-crystal EPR study  

NASA Astrophysics Data System (ADS)

We present a novel X-band electron paramagnetic resonance (EPR) signal in linear trimer Ni 3(dpa) 4Cl 2 crystal (dpa-dipyridylamine). The EPR signal displays rhombic symmetry with multi-nitrogen hyperfine splittings. The observed signal is assigned to S= {1}/{2} defect centered at the nickel site with gx=2.304, gy=2.199, gz=2.151 and hyperfine interaction strength of | A?|=7.7 G and | A?|=8.4 G with the four coordinating nitrogen nuclei.

Ke, S. C.; Gu, Y. T.

2003-06-01

322

On the Application of Symmetric Dirichlet Distributions and their Mixtures to Contingency Tables  

Microsoft Academic Search

Bayes factors against various hypotheses of independence are proposed for contingency tables and for multidimensional contingency tables. The priors assumed for the nonnull hypothesis are linear combinations of symmetric Dirichlet distributions as in some work of 1965 and later. The results can be used also for probability estimation. The evidence concerning independence, provided by the marginal totals alone, is evaluated,

I. J. Good

1976-01-01

323

Design and Implementation of a Scalable Parallel Direct Solver for Sparse Symmetric Positive Definite Systems  

E-print Network

equations is at the heart of many engineering and scientific computing applications. There are two methodsDesign and Implementation of a Scalable Parallel Direct Solver for Sparse Symmetric Positive Karypis z Vipin Kumar z Abstract Solving large sparse systems of linear equations is at the core of many

Kumar, Vipin

324

Design and Implementation of a Scalable Parallel Direct Solver for Sparse Symmetric Positive De nite Systems  

E-print Network

Design and Implementation of a Scalable Parallel Direct Solver for Sparse Symmetric Positive De Kumarz Abstract Solving large sparse systemsof linear equations is at the core of manyproblemsin engineering and scienti c computing. It has long been a challenge to develop parallel formulations of sparse

Karypis, George

325

Hamiltonian formulation of the standard PT-symmetric nonlinear Schrödinger dimer  

NASA Astrophysics Data System (ADS)

The standard PT-symmetric dimer is a linearly coupled two-site discrete nonlinear Schrödinger equation with one site losing and the other one gaining energy at the same rate. We show that despite gain and loss, the standard PT dimer is a Hamiltonian system. We also produce a Lagrangian formulation for the dimer.

Barashenkov, I. V.

2014-10-01

326

Quantum Chaos in Non-Symmetric Potential Well in a Tilted Magnetic Field  

Microsoft Academic Search

In this paper, the dynamical behavior of a non-symmetric double potential well in a tilted magnetic field is studied. The classical Poincare section is given to exhibit the chaotic behavior of the system, and non-linear resonant lead to chaos. The paper has also given the energy spectral statistics which satisfies Brody's distribution, tunnelling effect develops quantum chaos and also holds

Guoyong Yuan; Shiping Yang; Hongling Fan; Hong Chang

2004-01-01

327

Single-molecule magnet behavior and magnetocaloric effect in ferromagnetically coupled Ln(III)-Ni(II)-Ni(II)-Ln(III) (Ln(III) = Dy(III) and Gd(III)) linear complexes.  

PubMed

New types of linear tetranuclear Ln(III)-Ni(II)-Ni(II)-Ln(III) (Ln(III) = Dy (1), Gd (2)) complexes have been prepared using the multidentate ligand N,N'-bis(3-methoxysalicylidene)-1,3-diaminobenzene, which has two sets of NO and OO' coordination pockets that are able to selectively accommodate Ni(II) and Ln(III) ions, respectively. The X-ray structure analysis reveals that the Ni(II) ions are bridged by phenylenediimine groups forming a 12-membered metallacycle in the central body of the complex, whereas the Ln(III) ions are located at both sides of the metallacycle and linked to the Ni(II) ions by diphenoxo bridging groups. Phenylenediimine and diphenoxo bridging groups transmit ferromagnetic exchange interactions between the two Ni(II) ions and between the Ni(II) and the Ln(III) ions, respectively. Complex 1 shows slow relaxation of the magnetization at zero field and a thermal energy barrier Ueff = 7.4 K with HDC = 1000 Oe, whereas complex 2 exhibits an S = 9 ground state and significant magnetocaloric effect (-?Sm = 18.5 J kg(-1) K(-1) at T = 3 K and ?B = 5 T). PMID:25350578

Meseguer, Carlos; Titos-Padilla, Silvia; Hänninen, Mikko M; Navarrete, R; Mota, A J; Evangelisti, Marco; Ruiz, José; Colacio, Enrique

2014-11-17

328

Detecting Symmetry and Symmetric Constellations of Features  

Microsoft Academic Search

A novel and efficient method is presented for grouping feature points on the basis of their underlying symmetry and characterising the symmetries present in an image. We show how symmetric pairs of features can be efficiently detected, how the symmetry bonding each pair is extracted and evaluated, and how these can be grouped into symmetric constellations that specify the domi-

Gareth Loyand; Jan-olof Eklundh

2006-01-01

329

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

330

Unfolding the fold-Hopf bifurcation in piecewise linear continuous differential systems with symmetry  

NASA Astrophysics Data System (ADS)

Three-dimensional symmetric piecewise linear differential systems near the conditions corresponding to the fold-Hopf bifurcation for smooth systems are considered. By introducing one small parameter, we study the bifurcation of limit cycles in passing through its critical value, when the three eigenvalues of the linear part at the origin are at the imaginary axis of the complex plane. The simultaneous bifurcation of three limit cycles is proved. Conditions for stability of these limit cycles are provided, and analytical expressions for their period and amplitude are obtained. Finally, we apply the achieved theoretical results to a generalized version of Chua’s circuit, showing that the fold-Hopf bifurcation takes place for a certain range of parameters.

Ponce, Enrique; Ros, Javier; Vela, Elísabet

2013-05-01

331

A QMR-based interior-point algorithm for solving linear programs  

Microsoft Academic Search

A new approach for the implementation of interior-point methods for solving linear programs is proposed. Its main feature\\u000a is the iterative solution of the symmetric, but highly indefinite 2×2-block systems of linear equations that arise within\\u000a the interior-point algorithm. These linear systems are solved by a symmetric variant of the quasi-minimal residual (QMR) algorithm,\\u000a which is an iterative solver for

Roland W. Freund; Florian Jarre

1997-01-01

332

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

333

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.

2003-04-09

334

Implimenting cholesky factorization for interior point methods of linear programming  

Microsoft Academic Search

Every iteration of an interior point method of large scale linear programming requires computing at least one orthogonal projection of the objective function gradient onto the null space of a linear operator defined by the problem constraint matrix A. The orthogonal projection itself is in turn dominated by the inversion of the symmetric matrix of form AçA , where ç

J. Gondzio

1993-01-01

335

Linear induction motor parameter determination on force development applications  

Microsoft Academic Search

The main goal in this paper is to present a linear induction motor parameter determination method when its destination is mainly the thrust development. This method is developed basically from the equivalence between the linear induction motor (LIM) and the ordinary asymmetrical induction motor. In this case the theory of symmetrical and asymmetrical components or positive, negative and zero sequence

Luciano Martins Neto; Euler B. dos Santos; J. R. Camacho

2000-01-01

336

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

337

Linear Inequalities  

NSDL National Science Digital Library

In this activity, students graph up to four linear inequalities on the same graph. Students can also graph individual points to see if they satisfy the conditions of the inequalities they graphed. This activity allows students to explore linear inequalities and examine the region that will satisfy multiple inequalities at once. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2010-01-01

338

Linear alkylbenzene  

Microsoft Academic Search

Linear alkylbenzene (LAB) was introduced in the mid-1960s as a raw material for cleaning products. Since then, continuing\\u000a and explosive research on its biodegradation and on its environmental and human toxicity has been performed. The efficiency\\u000a of linear alkylbenzene sulfonate as surfactant is clearly established, and it is one of the safest and most cost-effective\\u000a products in widespread commercial use.

J. L. G. de Almeida; M. Dufaux; Y. Ben Taarit; C. Naccache

1994-01-01

339

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

340

Baryon symmetric big bang cosmology  

NASA Technical Reports Server (NTRS)

Both the quantum theory and Einsteins theory of special relativity lead to the supposition that matter and antimatter were produced in equal quantities during the big bang. It is noted that local matter/antimatter asymmetries may be reconciled with universal symmetry by assuming (1) a slight imbalance of matter over antimatter in the early universe, annihilation, and a subsequent remainder of matter; (2) localized regions of excess for one or the other type of matter as an initial condition; and (3) an extremely dense, high temperature state with zero net baryon number; i.e., matter/antimatter symmetry. Attention is given to the third assumption, which is the simplest and the most in keeping with current knowledge of the cosmos, especially as pertains the universality of 3 K background radiation. Mechanisms of galaxy formation are discussed, whereby matter and antimatter might have collided and annihilated each other, or have coexisted (and continue to coexist) at vast distances. It is pointed out that baryon symmetric big bang cosmology could probably be proved if an antinucleus could be detected in cosmic radiation.

Stecker, F. W.

1978-01-01

341

PT-symmetric laser absorber  

NASA Astrophysics Data System (ADS)

In a recent work, Y. D. Chong [Phys. Rev. Lett.0031-900710.1103/PhysRevLett.105.053901 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 (PT) symmetry condition ?(-r)=?*(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 thus be referred to as a PT-symmetric CPA laser. The general amplification or absorption features of the PT CPA laser below lasing threshold driven by two fields are determined.

Longhi, Stefano

2010-09-01

342

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

343

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

344

Symmetric Informationally Complete Measurements of Arbitrary Rank  

E-print Network

There has been much interest in so-called SIC-POVMs: rank 1 symmetric informationally complete positive operator valued measures. In this paper we discuss the larger class of POVMs which are symmetric and informationally complete but not necessarily rank 1. This class of POVMs is of some independent interest. In particular it includes a POVM which is closely related to the discrete Wigner function. However, it is interesting mainly because of the light it casts on the problem of constructing rank 1 symmetric informationally complete POVMs. In this connection we derive an extremal condition alternative to the one derived by Renes et al.

D. M. Appleby

2006-11-27

345

Target Space Pseudoduality Between Dual Symmetric Spaces  

E-print Network

A set of on shell duality equations is proposed that leads to a map between strings moving on symmetric spaces with opposite curvatures. The transformation maps "waves" on a riemannian symmetric space to "waves" on its dual riemannian symmetric space. This transformation preserves the energy momentum tensor though it is not a canonical transformation. The preservation of the energy momentum tensor has a natural geometrical interpretation. The transformation maps "particle-like solutions" into static "soliton-like solutions". The results presented here generalize earlier results of E. Ivanov.

Orlando Alvarez

2000-05-03

346

The cost of linearization  

NASA Astrophysics Data System (ADS)

Information processing in the brain is metabolically expensive and energy usage by the different components of the nervous system is not well understood. In a continuing effort to explore the costs and constraints of information processing at the single neuron level, dendritic processes are being studied. More specifically, the role of various ion channel conductances is explored in terms of integrating dendritic excitatory synaptic input. Biophysical simulations of dendritic behavior show that the complexity of voltage-dependent, non-linear dendritic conductances can produce simplicity in the form of linear synaptic integration. Over increasing levels of synaptic activity, it is shown that two types of voltage-dependent conductances produce linearization over a limited range. This range is determined by the parameters defining the ion channel and the 'passive' properties of the dendrite. A persistent sodium and a transient A-type potassium channel were considered at steady-state transmembrane potentials in the vicinity of and hyperpolarized to the threshold for action potential initiation. The persistent sodium is seen to amplify and linearize the synaptic input over a short range of low synaptic activity. In contrast, the A-type potassium channel has a broader linearization range but tends to operate at higher levels of synaptic bombardment. Given equivalent 'passive' dendritic properties, the persistent sodium is found to be less costly than the A-type potassium in linearizing synaptic input.

Morel, Danielle; Levy, William B.

2006-03-01

347

Reversal of multidrug resistance by reduction-sensitive linear cationic click polymer/iMDR1-pDNA complex nanoparticles.  

PubMed

A reduction-sensitive linear cationic click polymer (RCP) was specially designed for the efficient gene delivery to overcome multidrug resistance (MDR) by RNA interference to silence the expression of P-glycoprotein (P-gp). RCP was synthesized via the "click chemistry" with disulfide bonds, amide-triazole moieties and secondary amine groups in the main chain. RCP could efficiently condense pDNA into nanoparticles (RCPNs) around 150 nm. Polyplex dissociation was observed in the presence of 2.5 mm DTT due to the cleavage of disulfide bonds, which indicated the efficient DNA release under the reduction condition. In vitro transfection and cytotoxicity experiments against human breast cancer MCF-7 cells and drug-resistant MCF-7/ADR cells showed that RCPNs could bring about higher transfection efficiency with much lower cytotoxicity than PEI/DNA nanoparticles. RCPNs loaded with plasmid iMDR1-pDNA could inhibit P-gp expression, increase adriamycin (ADR) accumulation and enhance cytotoxicity of ADR against MCF-7/ADR cells. Combination of RCPNs and ADR could suppress the tumor growth more efficiently than using ADR only on mouse xenograft model bearing ADR resistant human breast cancer. These results suggested that this RCP could be a potential, safe and efficient non-viral vector for reversing MDR. PMID:21112086

Gao, Yu; Chen, Lingli; Zhang, Zhiwen; Chen, Yi; Li, Yaping

2011-02-01

348

Development of the complex general linear model in the Fourier domain: application to fMRI multiple input-output evoked responses for single subjects.  

PubMed

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

349

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

350

Towards an exact theory of linear absorbance and circular dichroism of pigment-protein complexes: Importance of non-secular contributions  

NASA Astrophysics Data System (ADS)

A challenge for the theory of optical spectra of pigment-protein complexes is the equal strength of the pigment-pigment and the pigment-protein couplings. Treating both on an equal footing so far can only be managed by numerically costly approaches. Here, we exploit recent results on a normal mode analysis derived spectral density that revealed the dominance of the diagonal matrix elements of the exciton-vibrational coupling in the exciton state representation. We use a cumulant expansion technique that treats the diagonal parts exactly, includes an infinite summation of the off-diagonal parts in secular and Markov approximations, and provides a systematic perturbative way to include non-secular and non-Markov corrections. The theory is applied to a model dimer and to chlorophyll (Chl) a and Chl b homodimers of the reconstituted water-soluble chlorophyll-binding protein (WSCP) from cauliflower. The model calculations reveal that the non-secular/non-Markov effects redistribute oscillator strength from the strong to the weak exciton transition in absorbance and they diminish the rotational strength of the exciton transitions in circular dichroism. The magnitude of these corrections is in a few percent range of the overall signal, providing a quantitative explanation of the success of time-local convolution-less density matrix theory applied earlier. A close examination of the optical spectra of Chl a and Chl b homodimers in WSCP suggests that the opening angle between Qy transition dipole moments in Chl b homodimers is larger by about 9? than for Chl a homodimers for which a crystal structure of a related WSCP complex exists. It remains to be investigated whether this change is due to a different mutual geometry of the pigments or due to the different electronic structures of Chl a and Chl b.

Dinh, Thanh-Chung; Renger, Thomas

2015-01-01

351

Towards an exact theory of linear absorbance and circular dichroism of pigment-protein complexes: importance of non-secular contributions.  

PubMed

A challenge for the theory of optical spectra of pigment-protein complexes is the equal strength of the pigment-pigment and the pigment-protein couplings. Treating both on an equal footing so far can only be managed by numerically costly approaches. Here, we exploit recent results on a normal mode analysis derived spectral density that revealed the dominance of the diagonal matrix elements of the exciton-vibrational coupling in the exciton state representation. We use a cumulant expansion technique that treats the diagonal parts exactly, includes an infinite summation of the off-diagonal parts in secular and Markov approximations, and provides a systematic perturbative way to include non-secular and non-Markov corrections. The theory is applied to a model dimer and to chlorophyll (Chl) a and Chl b homodimers of the reconstituted water-soluble chlorophyll-binding protein (WSCP) from cauliflower. The model calculations reveal that the non-secular/non-Markov effects redistribute oscillator strength from the strong to the weak exciton transition in absorbance and they diminish the rotational strength of the exciton transitions in circular dichroism. The magnitude of these corrections is in a few percent range of the overall signal, providing a quantitative explanation of the success of time-local convolution-less density matrix theory applied earlier. A close examination of the optical spectra of Chl a and Chl b homodimers in WSCP suggests that the opening angle between Qy transition dipole moments in Chl b homodimers is larger by about 9(?) than for Chl a homodimers for which a crystal structure of a related WSCP complex exists. It remains to be investigated whether this change is due to a different mutual geometry of the pigments or due to the different electronic structures of Chl a and Chl b. PMID:25612686

Dinh, Thanh-Chung; Renger, Thomas

2015-01-21

352

Radially-symmetric reflection maps  

Microsoft Academic Search

When designing lighting for outdoor scenes, area lights can represent distant sources such as the sun and sky with greater shading fidelity than is possible with simple directional or hemispherical lights, but the combination of dynamic area light sources and complex BRDFs is challenging to render efficiently in real-time. Prefiltered reflection maps are a popular solution to this problem, but

Jonathan Stone

2009-01-01

353

Dynamics of intense particle beam in axial-symmetric magnetic field  

NASA Astrophysics Data System (ADS)

Axial-symmetric magnetic field is often used in focusing of particle beams. Most existing ion Low Energy Beam Transport lines are based on solenoid focusing. Modern accelerator projects utilize superconducting solenoids in combination with superconducting accelerating cavities for acceleration of high-intensity particle beams. Present article discusses conditions for matched beam in axial-symmetric magnetic field. Analysis allows us to minimize power consumption of solenoids and beam emittance growth due to nonlinear space charge, lens aberrations, and maximize acceptance of the channel. Expressions for maximum beam current in focusing structure, beam emittance growth due to spherical aberrations and non-linear space charge forces are derived.

Batygin, Yuri K.

2015-02-01

354

Gaussian-type light bullets in power-law nonlinear media with PT-symmetric potentials  

NASA Astrophysics Data System (ADS)

The (3+1)-dimensional nonlinear Schrödinger equation with power-law nonlinearities in two kinds of PT-symmetric potentials is investigated, and two kinds of Gaussian-type light bullet (LB) solutions are analytically derived. Based on these analytical solutions, the powers, power-flow densities and the phase switches are discussed. The linear stability analysis and the direct numerical simulation show that LB solutions are stable only when the imaginary parts of PT-symmetric potentials are below some thresholds in the focusing power-law nonlinear media, while they are always unstable in the defocusing power-law nonlinear media.

Chen, Yi-Xiang; Dai, Chao-Qing

2015-03-01

355

Self-Gravitating Spherically Symmetric Solutions in Scalar-Torsion Theories  

E-print Network

We studied spherically symmetric solutions in scalar-torsion gravity theories in which a scalar field is coupled to torsion with a derivative coupling. We obtained the general field equations from which we extracted a decoupled master equation, the solution of which leads to the specification of all other unknown functions. We first obtained an exact solution which represents a new wormhole-like solution dressed with a regular scalar field. Then, we found large distance linearized spherically symmetric solutions in which the space asymptotically is AdS.

Kofinas, Georgios; Saridakis, Emmanuel N

2015-01-01

356

On the local form of static plane symmetric space-times in the presence of matter  

E-print Network

For any configuration of a static plane-symmetric distribution of matter along space-time, there are coordinates where the metric can be put explicitly as a functional of the energy density and pressures. It satisfies Einstein equations as far as we require the conservation of the energy-momentum tensor, which is the single ODE for self-gravitating hydrostatic equilibrium. As a direct application, a general solution is given when the pressures are linearly related to the energy density, recovering, as special cases, most of known solutions of static plane-symmetric Einstein equations.

Leandro G. Gomes

2015-02-10

357

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

2014-12-21

358

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

359

Linear theory and simulations of current sheet instabilities  

Microsoft Academic Search

A linear perturbation theory is developed for thin Harris-type current sheets in order to follow the continuous transition between different types of electromagnetic instabilities of plane current sheets. Only symmetrical perturbations across the sheet are considered. Thus, we do not discuss the drift-kink instability (DKI) but limit our scope to symmetric instabilities of tearing and sausage-types. The general dispersion relation

I. Silin; J. Büchner; L. Zelenyi

2001-01-01

360

Time-Symmetric Quantum Theory of Smoothing  

E-print Network

Smoothing is an estimation technique that takes into account both past and future observations and can be more accurate than filtering alone. In this Letter, a quantum theory of smoothing is constructed using a time-symmetric ...

Tsang, Mankei

361

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

362

PT Symmetric Quantum Electrodynamics Carl M. Bender #  

E-print Network

PT ­Symmetric Quantum Electrodynamics Carl M. Bender # Theoretical Physics, Blackett Laboratory, Norman, OK 73019, USA (Dated: January 21, 2005) Abstract The Hamiltonian for quantum electrodynamics­ Hermitian quantum electrodynamics is constructed perturbatively. This construction demonstrates

Milton, Kim

363

A Survey of Spherically Symmetric Spacetimes  

E-print Network

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.

Alan R. Parry

2014-09-20

364

Spherically symmetric brane spacetime with bulk gravity  

NASA Astrophysics Data System (ADS)

Introducing term in the five-dimensional bulk action we derive effective Einstein's equation on the brane using Gauss-Codazzi equation. This effective equation is then solved for different conditions on dark radiation and dark pressure to obtain various spherically symmetric solutions. Some of these static spherically symmetric solutions correspond to black hole solutions, with parameters induced from the bulk. Specially, the dark pressure and dark radiation terms (electric part of Weyl curvature) affect the brane spherically symmetric solutions significantly. We have solved for one parameter group of conformal motions where the dark radiation and dark pressure terms are exactly obtained exploiting the corresponding Lie symmetry. Various thermodynamic features of these spherically symmetric space-times are studied, showing existence of second order phase transition. This phenomenon has its origin in the higher curvature term with gravity in the bulk.

Chakraborty, Sumanta; SenGupta, Soumitra

2015-01-01

365

Linear stability of multilayer plane Poiseuille flows of Oldroyd B fluids  

Microsoft Academic Search

The linear stability of plane Poiseuille flows of two and three-symmetrical layers is studied by using both longwave and moderate wavelength analysis. The considered fluids follow Oldroyd-B constitutive equations and hence the stability is controlled by the viscous and elastic stratifications and the layer thicknesses. For the three symmetrical-layer Poiseuille flow, competition between varicose (symmetrical) and sinuous (antisymmetrical) mode is

P. Laure; H. Le Meur; Y. Demay; J. C. Saut; S. Scotto

1997-01-01

366

PSEUDOSPECTRA OF LINEAR OPERATORS  

Microsoft Academic Search

If a matrix or linear operator A is far from normal, its eigenvalues or, more generally, its spectrum may have little to do with its behavior as measured by quantities such as kAnk or kexp(tA)k. More may be learned by examining the sets in the complex plane known as the pseu- dospectra of A, dened by level curves of the

LLOYD N. TREFETHENy; SIAM REV

367

Time Symmetric Quantum Cosmology and Our Universe  

E-print Network

We investigate the time neutral formulation of quantum cosmology of Gell-Mann and Hartle. In particular we study the proposal discussed by them that our Universe corresponds to the time symmetric decoherence functional with initial and final density matrix of low entropy. We show that our Universe does not correspond to this proposal by investigating the behaviour of small inhomogeneous perturbations around a Friedman-Robertson-Walker model. These perturbations cannot be time symmetric if they were small at the Big Bang.

Raymond Laflamme

1993-01-08

368

Symmetric-key cryptosystem with DNA technology  

Microsoft Academic Search

DNA cryptography is a new field which has emerged with progress in the research of DNA computing. In our study, a symmetric-key\\u000a cryptosystem was designed by applying a modern DNA biotechnology, microarray, into cryptographic technologies. This is referred\\u000a to as DNA symmetric-key cryptosystem (DNASC). In DNASC, both encryption and decryption keys are formed by DNA probes, while\\u000a its ciphertext is

Mingxin Lu; Xuejia Lai; Guozhen Xiao; Lei Qin

2007-01-01

369

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

370

Characterization of Randomly Time-Variant Linear Channels  

Microsoft Academic Search

This paper is concerned with various aspects of the characterization of randomly time-variant linear channels. At the outset it is demonstrated that time-varying linear channels (or filters) may be characterized in an interesting symmetrical manner in time and frequency variables by arranging system functions in (timefrequency) dual pairs. Following this a statistical characterization of randomly time-variant linear channels is carried

P. Bello

1963-01-01

371

Optical Simulation of Axially Symmetrical Vertically Aligned Liquid Crystal Displays With Circularly Symmetric Iso-Contrast  

Microsoft Academic Search

This investigation reports the optical simulation of axially symmetric vertically aligned liquid crystal displays (ASVA LCDs). The circularly symmetric iso-light leakage and iso-transmittance contours of one subpixel result in the circularly symmetric iso-contrast contours. The contrast ratio of the area close to - and -axes at a polar angle of around 30 exceeds 10. The LCs near some azimuthal angles

Cheng-Kai Liu; Chi-Lun Ting; Ming-Shian Li; Andy Ying-Guey Fuh; Ko-Ting Cheng

2011-01-01

372

Informational approach to the quantum symmetrization postulate  

NASA Astrophysics Data System (ADS)

A remarkable feature of quantum theory is that particles with identical intrinsic properties must be treated as indistinguishable if the theory is to give valid predictions in all cases. In the quantum formalism, indistinguishability is expressed via the symmetrization postulate (Dirac P 1926 Proc. R. Soc. A 112 661, Heisenberg W 1926 Z. Phys. 38 411), which restricts a system of identical particles to the set of symmetric states (‘bosons’) or the set of antisymmetric states (‘fermions’). However, the physical basis and range of validity of the symmetrization postulate has not been established. A well-known topological derivation of the postulate implies that its validity depends on the dimensionality of the space in which the particles move (Laidlaw M and DeWitt C 1971 Phys. Rev. D 3 1375–8, Leinaas J M and Myrheim J 1977 Il Nuovo Cimento B 37 1–23). Here we show that the symmetrization postulate can be derived by strictly adhering to the informational requirement that particles which cannot be experimentally distinguished from one another are not labelled. Our key novel postulate is the operational indistinguishability postulate, which posits that the amplitude of a process involving several indistinguishable particles is determined by the amplitudes of all possible transitions of these particles when treated as distinguishable. The symmetrization postulate follows by requiring consistency with the rest of the quantum formalism. The derivation implies that the symmetrization postulate admits no natural variants. In particular, the possibility that identical particles generically exhibit anyonic behavior in two dimensions is excluded.

Goyal, Philip

2015-01-01

373

Competing PT potentials and re-entrant PT symmetric phase for a particle in a box  

E-print Network

We investigate the effects of competition between two complex, $\\mathcal{PT}$-symmetric potentials on the $\\mathcal{PT}$-symmetric phase of a "particle in a box". These potentials, given by $V_Z(x)=iZ\\mathrm{sign}(x)$ and $V_\\xi(x)=i\\xi[\\delta(x-a)-\\delta(x+a)]$, represent long-range and localized gain/loss regions respectively. We obtain the $\\mathcal{PT}$-symmetric phase in the $(Z,\\xi)$ plane, and find that for locations $\\pm a$ near the edge of the box, the $\\mathcal{PT}$-symmetric phase is strengthened by additional losses to the loss region. We also predict that a broken $\\mathcal{PT}$-symmetry will be restored by increasing the strength $\\xi$ of the localized potential. By comparing the results for this problem and its lattice counterpart, we show that a robust $\\mathcal{PT}$-symmetric phase in the continuum is consistent with the fragile phase on the lattice. Our results demonstrate that systems with multiple, $\\mathcal{PT}$-symmetric potentials show unique, unexpected properties.

Yogesh N. Joglekar; Bijan Bagchi

2012-06-14

374

Nonlinear Schrödinger equation for a PT symmetric delta-functions double well  

E-print Network

The time-independent nonlinear Schr\\"odinger equation is solved for two attractive delta-function shaped potential wells where an imaginary loss term is added in one well, and a gain term of the same size but with opposite sign in the other. We show that for vanishing nonlinearity the model captures all the features known from studies of PT symmetric optical wave guides, e.g., the coalescence of modes in an exceptional point at a critical value of the loss/gain parameter, and the breaking of PT symmetry beyond. With the nonlinearity present, the equation is a model for a Bose-Einstein condensate with loss and gain in a double well potential. We find that the nonlinear Hamiltonian picks as stationary eigenstates exactly such solutions which render the nonlinear Hamiltonian itself PT symmetric, but observe coalescence and bifurcation scenarios different from those known from linear PT symmetric Hamiltonians.

Holger Cartarius; Daniel Haag; Dennis Dast; Günter Wunner

2012-07-06

375

Advances in Interior Point Methods for Large-Scale Linear Programming  

Microsoft Academic Search

This research studies two computational techniques that improve the practical performance of existing implementations of interior point methods for linear programming. Both are based on the concept of symmetric neighbourhood as the driving tool for the analysis of the good performance of some practical algorithms. The symmetric neighbourhood adds explicit upper bounds on the complementarity pairs, besides the lower bound

Marco Colombo

2007-01-01

376

Symmetric Galerkin boundary formulations employing curved elements  

NASA Technical Reports Server (NTRS)

Accounts of the symmetric Galerkin approach to boundary element analysis (BEA) have recently been published. This paper attempts to add to the understanding of this method by addressing a series of fundamental issues associated with its potential computational efficiency. A new symmetric Galerkin theoretical formulation for both the (harmonic) heat conduction and the (biharmonic) elasticity problem that employs regularized singular and hypersingular boundary integral equations (BIEs) is presented. The novel use of regularized BIEs in the Galerkin context is shown to allow straightforward incorporation of curved, isoparametric elements. A symmetric reusable intrinsic sample point (RISP) numerical integration algorithm is shown to produce a Galerkin (i.e., double) integration strategy that is competitive with its counterpart (i.e., singular) integration procedure in the collocation BEA approach when the time saved in the symmetric equation solution phase is also taken into account. This new formulation is shown to be capable of employing hypersingular BIEs while obviating the requirement of C 1 continuity, a fact that allows the employment of the popular continuous element technology. The behavior of the symmetric Galerkin BEA method with regard to both direct and iterative equation solution operations is also addressed. A series of example problems are presented to quantify the performance of this symmetric approach, relative to the more conventional unsymmetric BEA, in terms of both accuracy and efficiency. It is concluded that appropriate implementations of the symmetric Galerkin approach to BEA indeed have the potential to be competitive with, if not superior to, collocation-based BEA, for large-scale problems.

Kane, J. H.; Balakrishna, C.

1993-01-01

377

An interior-point method for generalized linear-fractional programming  

Microsoft Academic Search

We develop an interior-point polynomial-time algorithm for a generalized linear-fractional problem. The latter problem can be regarded as a nonpolyhedral extension of the usual linear-fractional programming; typical example (which is of interest for control theory) is the minimization of the generalized eigenvalue of a pair of symmetric matrices linearly depending on the decision variables.

Yurii Nesterov; A. S. Nemirovskii

1995-01-01

378

Does Inflammatory Linear Verrucous Epidermal Nevus Represent a Segmental Type 1\\/Type 2 Mosaic of Psoriasis?  

Microsoft Academic Search

Background: A 6-year-old girl with a symmetric linear eruption on both of her legs, clinically and histologically resembling inflammatory linear verrucous epidermal nevus (ILVEN) or linear psoriasis (LP), with concomitant psoriasis of the guttata type and a positive family history of psoriasis is presented. The questions as to whether LP actually exists and ILVEN represents a distinct entity are still

Thomas Hofer

2006-01-01

379

Algebraic theory of linear viscoelastic nemattodynamics Part 2: Linear viscoelastic nematic viscoelasticity  

E-print Network

This second part of paper develops a theory of linear viscoelastic nematodynamics applicable to LCP. The viscous and elastic nematic components in theory are described by using the LEP approach for viscous nematics and de Gennes free energy for weakly elastic nematic elastomers. The case of applied external magnetic field exemplifies the occurrence of non-symmetric stresses. In spite of multi- (10) parametric character of the theory, the use of nematic operators presents it in an elegant form. When the magnetic field is absent, the theory is simplified for symmetric case with 6 parameters, and takes an extremely simple, 2-parametric form for viscoelastic nematodynamics with possible soft deformation modes. It is shown that the linear nematodynamics is always reduced to the LEP-like equations where the coefficients are changed for linear memory functionals whose parameters are calculated from original viscosities and moduli.

Arkady I. Leonov

2004-09-10

380

Complex Trajectories of a Simple Pendulum  

E-print Network

The motion of a classical pendulum in a gravitational field of strength g is explored. The complex trajectories as well as the real ones are determined. If g is taken to be imaginary, the Hamiltonian that describes the pendulum becomes PT-symmetric. The classical motion for this PT-symmetric Hamiltonian is examined in detail. The complex motion of this pendulum in the presence of an external periodic forcing term is also studied.

Carl M. Bender; Darryl D. Holm; Daniel W. Hook

2006-09-25

381

A Terminal, Fluxional ?(4) -Benzene Complex with a Thermally Accessible Triplet State is the Primary Photoproduct in the Intercyclobutadiene Haptotropism of (CpCo)phenylenes.  

PubMed

Low-temperature irradiation of linear [3]- and [4]phenylene cyclopentadienylcobalt complexes generates labile, fluxional ?(4) -arene complexes, in which the metal resides on the terminal ring. Warming induces a haptotropic shift to the neighboring cyclobutadiene rings, followed by the previously reported intercyclobutadiene migration. NMR scrutiny of the primary photoproduct reveals a thermally accessible 16-electron cobalt ?(2) -triplet species, which, according to DFT computations, is responsible for the rapid symmetrization of the molecules along their long axes. Calculations indicate that the entire haptotropic manifold along the phenylene frame is governed by dual-state reactivity of alternating 18-electron singlets and 16-electron triplets. PMID:25644142

Albright, Thomas A; Drissi, Rima; Gandon, Vincent; Oldenhof, Sander; Oloba-Whenu, Oluwakemi A; Padilla, Robin; Shen, Hao; Vollhardt, K Peter C; Vreeken, Vincent

2015-03-16

382

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.

Frank Wattenberg

1997-01-01

383

Elements of Cryptography.Elements of Cryptography. Symmetric Encryption.Symmetric Encryption.  

E-print Network

COMP 522 Elements of Cryptography.Elements of Cryptography. Symmetric Encryption.Symmetric Encryption. NSE, sections 2.1-2.2 WSPC, chapter 3 COMP 522 Cryptography · Cryptography is a collection of mathematical techniques for protecting information; · Most important technique is encryption/decryption; · We

Fisher, Michael

384

Synthesis and physical properties of symmetrical and non-symmetrical triacylglycerols containing two palmitic fatty acids  

Technology Transfer Automated Retrieval System (TEKTRAN)

Both the amounts of and specific structures of the triacylglycerols (TAG) present in the oil phase of a margarine or spread are considered responsible for such properties as its spreadability, resistance to water/oil loss, and melting characteristics. A series of symmetrical and non-symmetrical TAG...

385

An almost symmetric Strang splitting scheme for nonlinear evolution equations?  

PubMed Central

In this paper we consider splitting methods for the time integration of parabolic and certain classes of hyperbolic partial differential equations, where one partial flow cannot be computed exactly. Instead, we use a numerical approximation based on the linearization of the vector field. This is of interest in applications as it allows us to apply splitting methods to a wider class of problems from the sciences. However, in the situation described, the classic Strang splitting scheme, while still being a method of second order, is not longer symmetric. This, in turn, implies that the construction of higher order methods by composition is limited to order three only. To remedy this situation, based on previous work in the context of ordinary differential equations, we construct a class of Strang splitting schemes that are symmetric up to a desired order. We show rigorously that, under suitable assumptions on the nonlinearity, these methods are of second order and can then be used to construct higher order methods by composition. In addition, we illustrate the theoretical results by conducting numerical experiments for the Brusselator system and the KdV equation.

Einkemmer, Lukas; Ostermann, Alexander

2014-01-01

386

Mercury(II) cysteine complexes in alkaline aqueous solution.  

PubMed

Mercury(II) complexes with l-cysteine (H(2)Cys) in alkaline aqueous solutions have been structurally characterized by means of extended X-ray absorption fine structure (EXAFS) spectroscopy. The distribution of [Hg(Cys)(n)] (n = 2, 3, and 4) species in approximately 0.09 mol dm(-3) mercury(II) solutions with H(2)Cys/Hg(II) ratios varying from 2.2 to 10.1 has been evaluated by fitting linear combinations of simulated EXAFS functions for the separate complexes to the experimental EXAFS data, aided by (199)Hg NMR and Raman results. For the [Hg(Cys)(2)](2-) and [Hg(Cys)(3)](4-) complexes and the novel four-coordinated Hg(Cys)(4) species that dominates in solutions with excess of cysteine (H(2)Cys/Hg(II) > 5), the mean Hg-S bond distances were found to be 2.35(2), 2.44(2), and 2.52(2) Angstroms, respectively. The minor amount of the linear [Hg(Cys)(2)](2-) complex that can still be discerned in solutions with ratios up to H(2)Cys/Hg(II) = 5 was derived from the distinct S-Hg-S symmetric stretching Raman band at 334 cm(-1). From (199)Hg NMR spectra, the chemical shift of the Hg(Cys)(4) species was estimated to -340 ppm with an amount exceeding 85% in the highest excess of cysteine, consistent with the EXAFS data. PMID:16390041

Jalilehvand, Farideh; Leung, Bonnie O; Izadifard, Maryam; Damian, Emiliana

2006-01-01

387

Lifetimes of spherically symmetric closed universes  

E-print Network

It is proven that any spherically symmetric spacetime that possesses a compact Cauchy surface \\Sigma and that satisfies the dominant-energy and non-negative-pressures conditions must have a finite lifetime in the sense that all timelike curves in such a spacetime must have a length no greater than 10 \\max_\\Sigma(2m), where m is the mass associated with the spheres of symmetry. This result gives a complete resolution, in the spherically symmetric case, of one version of the closed-universe recollapse conjecture (though it is likely that a slightly better bound can be established). This bound has the desirable properties of being computable from the (spherically symmetric) initial data for the spacetime and having a very simple form. In fact, its form is the same as was established, using a different method, for the spherically symmetric massless scalar field spacetimes, thereby proving a conjecture offered in that work. Prospects for generalizing these results beyond the spherically symmetric case are discusse...

Burnett, G A

1995-01-01

388

p-n configurations of symmetric and mixed-symmetric states  

NASA Astrophysics Data System (ADS)

The first 2^+ state in collective even-even nuclei is a proton-neutron (pn) symmetric quadrupole excitation. It has a mixed-symmetric counterpart, which has p-n anti-symmetric parts in the wavefunction. A strong p-n interaction mixes the proton and neutron configuration, creating a low-lying symmetric state and a higher-lying mixed-symmetric state. The significant energy difference between the proton and neutron j=2 configurations and rather weak mixing between the proton and neutron state wavefunctions in Zr isotopes results in a 2^+1 state with neutron dominance and a 2^+2 state with proton dominance, which was identified as the one-phonon mixed-symmetry 2^+ state. This signature in Zr provides an ideal basis for studying configuration mixing. This mixing is studied experimentally by measuring g factors. Theoretical predictions will be compared with recent experimental results.

Perry, M.; Werner, V.; Pietralla, N.; Benczer-Koller, N.

2006-10-01

389

Stability analysis and control of the flow in a symmetric channel with a sudden expansion  

NASA Astrophysics Data System (ADS)

The laminar flow in two-dimensional diffusers may produce either symmetric or nonsymmetric steady solutions, depending on the value of the Reynolds number as compared with some critical value. The stability properties of the flow are studied in the context of linear theory. In this context, a sensitivity analysis of the flow instability is carried out with respect to perturbations that may be produced by a realistic passive control, thus providing qualitative hints and quantitative information for the control design. Following the so-obtained information, a passive control is built by introducing a small cylinder in the flow with the aim of stabilizing the unstable symmetric flow configuration in the diffuser. The effectiveness of this control is finally assessed by direct numerical simulation. It is shown that the introduction of the cylinder, placed following the indications of the linear sensitivity analysis in the stable asymmetric flow configuration, allows a steady completely symmetric or less asymmetric flow to be recovered. The flow transient between the uncontrolled asymmetric solution and the symmetric controlled one is analyzed in terms of streamlines and vorticity evolution; the effects of the cylinder introduction on flow dissipation are also assessed.

Fani, Andrea; Camarri, Simone; Salvetti, Maria Vittoria

2012-08-01

390

Honors problem 1: Complex numbers. Arithmetic of complex numbers  

E-print Network

Honors problem 1: Complex numbers. Arithmetic of complex numbers Recall that the complex numbers identify the complex numbers with the set of linear polynomials with real coefficients). The numbers as a subset of the complex numbers by identifying the real number a with a+0i. The imaginary numbers

Leininger, Christopher J.

391

Honors problem 1: Complex numbers. Arithmetic of complex numbers  

E-print Network

Honors problem 1: Complex numbers. Arithmetic of complex numbers Recall that the complex numbers we can identify the complex numbers with the set of linear polynomials with real coefficients as a subset of the complex numbers by identifying the real number a with a + 0i. The imaginary numbers

Leininger, Christopher J.

392

Application of Cellular Automata in Symmetric Key Cryptography  

NASA Astrophysics Data System (ADS)

The main concern of this paper is cryptosystems with a symmetric key, in particular block ciphers. The most important components of block ciphers are substitution boxes (S-boxes). Developing methods of cryptanalysis make ciphers worked on classical S-boxes not safe enough. Therefore, we propose a methodology of generation cellular automata (CA)-based S-boxes with enhanced quality. We provide an exhaustive experimental analysis of the proposed CA-based S-boxes in terms of non-linearity, autocorrelation, balance and strict avalanche criterion. We show that proposed S-boxes have high cryptographic quality. The interesting feature of the proposed S-boxes is a dynamic flexible structure, fully functionally realized by CA, while the classical S-boxes are represented by fixed table structures.

Szaban, Miroslaw; Nowacki, Jerzy Pawel; Drabik, Aldona; Seredynski, Franciszek; Bouvry, Pascal

393

Symmetric nonnegative matrix factorization: algorithms and applications to probabilistic clustering.  

PubMed

Nonnegative matrix factorization (NMF) is an unsupervised learning method useful in various applications including image processing and semantic analysis of documents. This paper focuses on symmetric NMF (SNMF), which is a special case of NMF decomposition. Three parallel multiplicative update algorithms using level 3 basic linear algebra subprograms directly are developed for this problem. First, by minimizing the Euclidean distance, a multiplicative update algorithm is proposed, and its convergence under mild conditions is proved. Based on it, we further propose another two fast parallel methods: ?-SNMF and ? -SNMF algorithms. All of them are easy to implement. These algorithms are applied to probabilistic clustering. We demonstrate their effectiveness for facial image clustering, document categorization, and pattern clustering in gene expression. PMID:22042156

He, Zhaoshui; Xie, Shengli; Zdunek, Rafal; Zhou, Guoxu; Cichocki, Andrzej

2011-12-01

394

Spherically symmetric cosmological spacetimes with dust and radiation — numerical implementation  

SciTech Connect

We present new numerical cosmological solutions of the Einstein Field Equations. The spacetime is spherically symmetric with a source of dust and radiation approximated as a perfect fluid. The dust and radiation are necessarily non-comoving due to the inhomogeneity of the spacetime. Such a model can be used to investigate non-linear general relativistic effects present during decoupling or big-bang nucleosynthesis, as well as for investigating void models of dark energy with isocurvature degrees of freedom. We describe the full evolution of the spacetime as well as the redshift and luminosity distance for a central observer. After demonstrating accuracy of the code, we consider a few example models, and demonstrate the sensitivity of the late time model to the degree of inhomogeneity of the initial radiation contrast.

Lim, Woei Chet [Department of Mathematics, University of Waikato, Private Bag 3105, Hamilton 3240 (New Zealand); Regis, Marco [Dipartimento di Fisica, Università di Torino and INFN, Torino (Italy); Clarkson, Chris, E-mail: wclim@waikato.ac.nz, E-mail: regis@to.infn.it, E-mail: chris.clarkson@gmail.com [Astrophysics, Cosmology and Gravity Centre, and Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa)

2013-10-01

395

Two loop QCD vertices at the symmetric point  

E-print Network

We compute the triple gluon, quark-gluon and ghost-gluon vertices of QCD at the symmetric subtraction point at two loops in the MSbar 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 MSbar 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.

J. A. Gracey

2011-08-24

396

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

397

Impact of semi-annihilation of Bbb Z3 symmetric dark matter with radiative neutrino masses  

NASA Astrophysics Data System (ADS)

We investigate a Bbb Z3 symmetric model with two-loop radiative neutrino masses. Dark matter in the model is either a Dirac fermion or a complex scalar as a result of an unbroken Bbb Z3 symmetry. In addition to standard annihilation processes, semi-annihilation of the dark matter contributes to the relic density. We study the effect of the semi-annihilation in the model and find that those contributions are important to obtain the observed relic density. The experimental signatures in dark matter searches are also discussed, where some of them are expected to be different from the signatures of dark matter in Bbb Z2 symmetric models.

Aoki, Mayumi; Toma, Takashi

2014-09-01

398

Finite element Calculations of {P}{T}-Symmetric Bose-Einstein Condensates  

NASA Astrophysics Data System (ADS)

PT-symmetric systems have been intensively studied in optical waveguides, where the PT symmetry is achieved by pumping and absorption processes. In such systems the PT symmetry leads to a wide range of effects promising technical and scientific applications. By analogy, balanced gain and loss of particles in Bose-Einstein condensates (BEC) can be described by introducing a PT-symmetric imaginary potential into the Gross-Pitaevskii equation (GPE). This equation can be solved numerically by various methods including the finite element approach. We apply this method to the GPE with arbitrary complex potentials and explicitly solve a double-well potential with shifted barriers.

Haag, Daniel; Dast, Dennis; Cartarius, Holger; Wunner, Günter

2015-01-01

399

PT-symmetric extensions of the supersymmetric Korteweg-de Vries equation  

E-print Network

We discuss several PT-symmetric deformations of superderivatives. Based on these various possibilities, we propose new families of complex PT-symmetric deformations of the supersymmetric Korteweg-de Vries equation. Some of these new models are mere fermionic extensions of the former in the sense that they are formulated in terms of superspace valued superfields containing bosonic and fermionic fields, breaking however the supersymmetry invariance. Nonetheless, we also find extensions, which may be viewed as new supersymmetric Korteweg-de Vries equation. Moreover, we show that these deformations allow for a non-Hermitian Hamiltonian formulation and construct three charges associated to the corresponding flow.

Bijan Bagchi; Andreas Fring

2008-07-11

400

Cervical Symmetric Dumbbell Ganglioneuromas Causing Severe Paresis  

PubMed Central

We report an extremely rare case with bilateral and symmetric dumbbell ganglioneuromas of the cervical spine in an elderly patient. A 72-year-old man came by ambulance to our hospital due to progressive incomplete paraplegia. Magnetic resonance imaging demonstrated bilateral symmetric dumbbell tumors at the C1/2 level. We performed total resection of the intracanalar tumor, aiming at complete decompression of the spinal cord, and partial and subtotal resection of foraminal outside portions. Histopathological examination of the surgical specimen indicated the tumor cells to be spindle cells with the presence of ganglion cells and no cellular pleomorphism, suggesting a diagnosis of ganglioneuroma. Although the surgery was not curative, the postoperative course was uneventful and provided a satisfactory outcome. This is the fourth known case of cervical ganglioneuromas of the bilateral symmetric dumbbell type. PMID:24596609

Miyamoto, Kei; Hirose, Yoshinobu; Kito, Yusuke; Fushimi, Kazunari; Shimizu, Katsuji

2014-01-01

401

Cervical symmetric dumbbell ganglioneuromas causing severe paresis.  

PubMed

We report an extremely rare case with bilateral and symmetric dumbbell ganglioneuromas of the cervical spine in an elderly patient. A 72-year-old man came by ambulance to our hospital due to progressive incomplete paraplegia. Magnetic resonance imaging demonstrated bilateral symmetric dumbbell tumors at the C1/2 level. We performed total resection of the intracanalar tumor, aiming at complete decompression of the spinal cord, and partial and subtotal resection of foraminal outside portions. Histopathological examination of the surgical specimen indicated the tumor cells to be spindle cells with the presence of ganglion cells and no cellular pleomorphism, suggesting a diagnosis of ganglioneuroma. Although the surgery was not curative, the postoperative course was uneventful and provided a satisfactory outcome. This is the fourth known case of cervical ganglioneuromas of the bilateral symmetric dumbbell type. PMID:24596609

Hioki, Akira; Miyamoto, Kei; Hirose, Yoshinobu; Kito, Yusuke; Fushimi, Kazunari; Shimizu, Katsuji

2014-02-01

402

Chiral light by symmetric optical antennas  

E-print Network

Chirality is at the origin of life and is ubiquitous in nature. An object is deemed chiral if it is non-superimposable with its own mirror image. This relates to how circularly polarized light interacts with such object, a circular dichroism, the differential absorption of right and left circularly polarized light. According to the common understanding in biology, chemistry and physics, the circular dichroism results from an internal chiral structure or external symmetry breaking by illumination. We show that circular dichroism is possible with simple symmetric optical nanoantennas at symmetric illumination. We experimentally and theoretically demonstrate that two electromagnetic dipole-like modes with a phase lag, in principle, suffice to produce circular dichroism in achiral structure. Examples of the latter are all visible spectrum optical nanoantennas, symmetric nanoellipses and nanodimers. The simplicity and generality of this finding reveal a whole new significance of the electromagnetic design at a nan...

Mekonnen, Addis; Zubritskaya, Irina; Jönsson, Gustav Edman; Dmitriev, Alexandre

2014-01-01

403

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

404

The quantum capacity with symmetric side channels  

E-print Network

We present an upper bound for the quantum channel capacity that is both additive and convex. Our bound can be interpreted as the capacity of a channel for high-fidelity quantum communication when assisted by a family of channels that have no capacity on their own. This family of assistance channels, which we call symmetric side channels, consists of all channels mapping symmetrically to their output and environment. The bound seems to be quite tight, and for degradable quantum channels it coincides with the unassisted channel capacity. Using this symmetric side channel capacity, we find new upper bounds on the capacity of the depolarizing channel. We also briefly indicate an analogous notion for distilling entanglement using the same class of (one-way) channels, yielding one of the few entanglement measures that is monotonic under local operations with one-way classical communication (1-LOCC), but not under the more general class of local operations with classical communication (LOCC).

Graeme Smith; John A. Smolin; Andreas Winter

2008-08-28

405

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

406

Systems of coupled PT-symmetric oscillators  

E-print Network

The Hamiltonian for a PT-symmetric chain of coupled oscillators is constructed. It is shown that if the loss-gain parameter $\\gamma$ is uniform for all oscillators, then as the number of oscillators increases, the region of unbroken PT-symmetry disappears entirely. However, if $\\gamma$ 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 pseudo-bound state. It is also shown that a planar configuration of coupled oscillators can have multiple disconnected regions of unbroken PT symmetry.

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

2014-06-23

407

Reduced-order modeling of large passive linear circuits by means of the SYPVL algorithm  

Microsoft Academic Search

. This paper discusses the analysis of large linear electrical networks consistingof passive components, resistors, capacitors, inductors, transformers, etc. Such networksresult in a symmetric formulation of circuit equations. The paper introduces SyPVL, anefficient and numerically stable algorithm for the computation of reduced-order models oflarge, linear, passive networks. SyPVL represents the specialization of the more generalPVL algorithm, to symmetric problems. Besides

Roland W. Freund; Peter Feldmann

1996-01-01

408

-symmetric nonlinear metamaterials and zero-dimensional systems  

NASA Astrophysics Data System (ADS)

A one dimensional, parity-time ()-symmetric magnetic metamaterial comprising split-ring resonators having both gain and loss is investigated. In the linear regime, the transition from the exact to the broken -phase is determined through the calculation of the eigenfrequency spectrum for two different configurations; the one with equidistant split-rings and the other with the split-rings forming a binary pattern ( dimer chain). The latter system features a two-band, gapped spectrum with its shape determined by the gain/loss coefficient as well as the interelement coupling. In the presence of nonlinearity, the dimer chain configuration with balanced gain and loss supports nonlinear localized modes in the form of a novel type of discrete breathers below the lower branch of the linear spectrum. These breathers that can be excited from a weak applied magnetic field by frequency chirping, can be subsequently driven solely by the gain for very long times. The effect of a small imbalance between gain and loss is also considered. Fundamental gain-driven breathers occupy both sites of a dimer, while their energy is almost equally partitioned between the two split-rings, the one with gain and the other with loss. We also introduce a model equation for the investigation of classical symmetry in zero dimensions, realized by a simple harmonic oscillator with matched time-dependent gain and loss that exhibits a transition from oscillatory to diverging motion. This behavior is similar to a transition from the exact to the broken phase in higher-dimensional -symmetric systems. A stability condition relating the parameters of the problem is obtained in the case of a piece-wise constant gain/loss function that allows the construction of a phase diagram with alternating stable and unstable regions.

Tsironis, G. P.; Lazarides, N.

2014-05-01

409

Classification of Six Derivative Lagrangians of Gravity and Static Spherically Symmetric Solutions  

E-print Network

We classify all the six derivative Lagrangians of gravity, whose traced field equations are of second or third order, in arbitrary dimensions. In the former case, the Lagrangian in dimensions greater than six, reduces to an arbitrary linear combination of the six dimensional Euler density and the two linearly independent cubic Weyl invariants. In five dimensions, besides the independent cubic Weyl invariant, we obtain an interesting cubic combination, whose field equations for static spherically symmetric spacetimes are of second order. In the later case, in arbitrary dimensions we obtain two combinations, which in dimension three, are equivalent to the complete contraction of two Cotton tensors. Moreover, we also recover all the conformal anomalies in six dimensions. Finally, we present some static, spherically symmetric solutions for these Lagrangians.

Julio Oliva; Sourya Ray

2010-11-15

410

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

411

CPT-symmetric discrete square well  

E-print Network

A new version of an elementary PT-symmetric square well quantum model is proposed in which a certain Hermiticity-violating end-point interaction leaves the spectrum real in a large domain of couplings $\\lambda\\in (-1,1)$. Within this interval we employ the usual coupling-independent operator P of parity and construct, in a systematic Runge-Kutta discrete approximation, a coupling-dependent operator of charge C which enables us to classify our P-asymmetric model as CPT-symmetric or, equivalently, hiddenly Hermitian alias cryptohermitian.

Znojil, Miloslav

2010-01-01

412

Influence of initial conditions in symmetric games  

NASA Astrophysics Data System (ADS)

It is known that quantum game is characterized by the payoff matrix as well as initial states of the quantum objects used as carriers of information in a game. Further, the initial conditions of the quantum states influence the strategies adopted by the quantum players. In this paper, we identify the necessary condition on the initial states of quantum objects for converting symmetric games into potential games, in which the players acquire the same payoff matrix. The necessary condition to preserve the symmetric type and potential type of the game is found to be the same. The present work emphasizes the influence of the initial states in the quantization of games.

Balakrishnan, S.

2014-12-01

413

Objective Non-linear  

E-print Network

Objective Linear Ferro- magnets Non-linear properties Electric. Conduct Ferro- magnets Non-linear properties Electric. Conduct. Tensors Elasticity;Objective Linear Ferro- magnets Non-linear properties Electric. Conduct. Tensors

Rollett, Anthony D.

414

Platonic Beasts: Spherically Symmetric Multilimbed Robots  

E-print Network

Platonic Beasts: Spherically Symmetric Multilimbed Robots Dinesh K. Pai Roderick A. Barman Scott K. Ralph Department of Computer Science University of British Columbia Vancouver, B.C. V6T 1Z4, Canada {pai beasts." A robot in this family is kinematically equivalent to a sym- metric polyhedron, such as one

Pai, Dinesh

415

NonceBased Symmetric Encryption Phillip Rogaway  

E-print Network

Nonce­Based Symmetric Encryption Phillip Rogaway Dept. of Computer Science, University encryption schemes are usually formalized so as to make the encryption operation a probabilistic or state­dependent func­ tion E of the message M and the key K: the user supplies M and K and the encryption process does

Rogaway, Phillip

416

Ch.19 Symmetric Encryption and Message Confidentiality  

E-print Network

1 1 Ch.19 Symmetric Encryption and Message Confidentiality · HW 9 and 10: upto this Wen · Next week: Ch.20 Public key Crypto · Conventional Encryption Principles · Conventional Encryption Algorithms: DES, AES · Cipher Block Modes of Operation: Block vs. stream · Location of Encryption Devices · Key

Dong, Yingfei

417

Cylindrically symmetric solutions in conformal gravity  

SciTech Connect

Cylindrically symmetric solutions in conformal gravity are investigated and several new solutions are presented and discussed, among them a family of vacuum solutions, generalizations of the Melvin solution, and cosmic strings of the Abelian Higgs model. The Melvin-like solutions have finite energy per unit length, while the stringlike solutions do not.

Brihaye, Y. [Physique Theorique et Mathematiques, Universite de Mons, Place du Parc, B-7000 Mons (Belgium); Verbin, Y. [Department of Natural Sciences, Open University of Israel, Raanana 43107 (Israel)

2010-06-15

418

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

2014-09-19

419

Spherically symmetric monopoles in noncommutative space  

E-print Network

We construct a spherically symmetric noncommutative space in three dimensions by foliating the space with concentric fuzzy spheres. We show how to construct a gauge theory in this space and in particular we derive the noncommutative version of a Yang-Mills-Higgs theory. We find numerical monopole solutions of the equations of motion.

E. F. Moreno

2005-06-16

420

1 Kastelyn's Theorem and Noneven Symmetric Digraphs*  

E-print Network

's Theorem and Noneven Symmetric Digraphs* By Chjan C. Lim e-mail: limc@rpi.edu Abstract A noneven digraph in no even cycles. A directed cycle in a weig* *hted digraph is even if the sum of weights of its arcs

Lim, Chjan C.

421

Vertex-symmetric Digraphs with Small Diameter  

Microsoft Academic Search

There is increasing interest in the design of dense vertex symmetric graphs and digraphs as models of interconnection networks for implementing parallelism. In these systems many nodes are connected with relatively few links and short paths between them and each node may execute, without modifications, the same com- munication software. In this paper we give new families of dense vertex

Francesc Comellas; Miguel Angel Fiol

1995-01-01

422

Symmetric space description of carbon nanotubes  

E-print Network

Using an innovative technique arising from the theory of symmetric spaces, we obtain an approximate analytic solution of the Dorokhov-Mello-Pereyra-Kumar (DMPK) equation in the insulating regime of a metallic carbon nanotube with symplectic symmetry and an odd number of conducting channels. This symmetry class is characterized by the presence of a perfectly conducting channel in the limit of infinite length of the nanotube. The derivation of the DMPK equation for this system has recently been performed by Takane, who also obtained the average conductance both analytically and numerically. Using the Jacobian corresponding to the transformation to radial coordinates and the parameterization of the transfer matrix given by Takane, we identify the ensemble of transfer matrices as the symmetric space of negative curvature SO^*(4m+2)/[SU(2m+1)xU(1)] belonging to the DIII-odd Cartan class. We rederive the leading-order correction to the conductance of the perfectly conducting channel and its variance Var(log(delta g)). Our results are in complete agreement with Takane's. In addition, our approach based on the mapping to a symmetric space enables us to obtain new universal quantities: a universal group theoretical expression for the ratio Var(log(delta g)/ and as a byproduct, a novel expression for the localization length for the most general case of a symmetric space with BC_m root system, in which all three types of roots are present.

M. Caselle; U. Magnea

2006-01-10

423

Support for Symmetric Shadow Memory in Multiprocessors  

E-print Network

(OMI) is then accompanied by additional shadow memory instructions (SMIs) that manipulate the meta data associated with the memory location. Often the SMIs associated with OMIs are symmetric, in that, origi- nal implementations need thread serialization to ensure that OMIs and SMIs are exe- cuted atomically [12]. Naturally

Gupta, Rajiv

424

Spherically symmetric monopoles in noncommutative space  

SciTech Connect

We construct a spherically symmetric noncommutative space in three dimensions by foliating the space with concentric fuzzy spheres. We show how to construct a gauge theory in this space, and, in particular, we derive the noncommutative version of a Yang-Mills-Higgs theory. We find numerical monopole solutions of the equations of motion.

Moreno, E.F. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina) and Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)

2005-08-15

425

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

426

Unidirectional nonlinear PT-symmetric optical structures  

SciTech Connect

We show that nonlinear optical structures involving a balanced gain-loss profile can act as unidirectional optical valves. This is made possible by exploiting the interplay between the fundamental symmetries of parity (P) and time (T), with optical nonlinear effects. This unidirectional dynamics is specifically demonstrated for the case of an integrable PT-symmetric nonlinear system.

Ramezani, Hamidreza [Department of Physics, Wesleyan University, Middletown, Connecticut 06459 (United States); Kottos, Tsampikos [Department of Physics, Wesleyan University, Middletown, Connecticut 06459 (United States); Max-Planck-Institute for Dynamics and Self-Organization, D-37073 Goettingen (Germany); El-Ganainy, Ramy; Christodoulides, Demetrios N. [College of Optics and Photonics-CREOL, University of Central Florida, Orlando, Florida 32816 (United States)

2010-10-15

427

Laws of Trigonometry in Symmetric Spaces  

Microsoft Academic Search

This paper consists of two parts. In the flrst part, we reformulate the work of E. Leuzinger on trigonometry in noncompact symmetric spaces. In the second part, we outline an alternative method using invariants of the isotropy group representation. Appropriately formulated, these methods apply to both compact and noncompact sym- metric spaces. This work is contained in the Ph.D. dissertation

Helmer Aslaksen; Hsueh-Ling Huynh

428

Axially symmetric potentials in the oscillator representation  

Microsoft Academic Search

The Wick-ordering method called the Oscillator Representation in the nonrelativistic Schrödinger equation is proposed to calculate the energy spectrum for axially symmetric potentials allowing the existence of a bound state. In particular, the method is applied to calculate the energy spectrum of (2s) states of a hydrogen atom in a uniform magnetic field of an arbitrary strength. In the perturbation

M. Dineykhan

1997-01-01

429

PT -Symmetric Quantum Electrodynamics Carl M. Bender  

E-print Network

PT -Symmetric Quantum Electrodynamics Carl M. Bender Theoretical Physics, Blackett Laboratory, OK 73019, USA (Dated: January 21, 2005) Abstract The Hamiltonian for quantum electrodynamics becomes is self-adjoint. In this paper the corresponding C operator for non- Hermitian quantum electrodynamics

Milton, Kim

430

Extending additivity from symmetric to asymmetric channels  

E-print Network

We prove a lemma which allows one to extend results about the additivity of the minimal output entropy from highly symmetric channels to a much larger class. A similar result holds for the maximal output $p$-norm. Examples are given showing its use in a variety of situations. In particular, we prove the additivity and the multiplicativity for the shifted depolarising channel.

Motohisa Fukuda

2005-08-14

431

Numerical evaluation of a symmetric potential function  

Microsoft Academic Search

We discuss the numerical evaluation of a symmetric potential func- tion which arises naturally in applications. We present a method designed to accurately and eciently compute this integral, and compare the performance of this method with two other popular techniques. This method requires con- siderably fewer function evaluations than all other techniques we tested, and is applicable to any integral

Lori A. Carmack

1998-01-01

432

Symmetric protein architecture in protein design: top-down symmetric deconstruction.  

PubMed

Top-down symmetric deconstruction (TDSD) is a joint experimental and computational approach to generate a highly stable, functionally benign protein scaffold for intended application in subsequent functional design studies. By focusing on symmetric protein folds, TDSD can leverage the dramatic reduction in sequence space achieved by applying a primary structure symmetric constraint to the design process. Fundamentally, TDSD is an iterative symmetrization process, in which the goal is to maintain or improve properties of thermodynamic stability and folding cooperativity inherent to a starting sequence (the "proxy"). As such, TDSD does not attempt to solve the inverse protein folding problem directly, which is computationally intractable. The present chapter will take the reader through all of the primary steps of TDSD-selecting a proxy, identifying potential mutations, establishing a stability/folding cooperativity screen-relying heavily on a successful TDSD solution for the common ?-trefoil fold. PMID:25213415

Longo, Liam M; Blaber, Michael

2014-01-01

433

Tensor Algebras, Symmetric Algebras and Exterior Algebras  

E-print Network

the space of sections of a tensor product of vector bundles. Given a linear map, f : E F, we know multilinear map, f : En F, is turned into a linear map, f : Symn (E) F, which is equivalent to f in a strong), and every alternating multilinear map is turned into a linear map, f : n (E) F, which is equivalent to f

Gallier, Jean

434

The Chernoff lower bound for symmetric quantum hypothesis testing  

E-print Network

We consider symmetric hypothesis testing in quantum statistics, where the hypotheses are density operators on a finite-dimensional complex Hilbert space, representing states of a finite quantum system. We prove a lower bound on the asymptotic rate exponents of Bayesian error probabilities. The bound represents a quantum extension of the Chernoff bound, which gives the best asymptotically achievable error exponent in classical discrimination between two probability measures on a finite set. In our framework, the classical result is reproduced if the two hypothetic density operators commute. Recently, it has been shown elsewhere [Phys. Rev. Lett. 98 (2007) 160504] that the lower bound is achievable also in the generic quantum (noncommutative) case. This implies that our result is one part of the definitive quantum Chernoff bound.

Michael Nussbaum; Arleta Szko?a

2009-04-27

435

Emittance growth in non-symmetric beam configurations  

SciTech Connect

Emittance growth in intense beams due to nonuniformity, mismatch, and misalignment has been analyzed by Reiser for the special case of axisymmetry. A more complex problem occurs in cases where a number of discrete beamlets are to be merged into a single focusing channel, for example, in designs for Heavy Ion Fusion drivers or Magnetic Fusion negative-ion systems. Celata, assuming the system to be perfectly matched and aligned, analyzed the case of four round beamlets arranged in a square array. We generalize these previous studies and analyze emittance growth in systems that are less symmetric. We include beam systems that are not necessarily matched and where the x and y moments may be unequal. We also include the possibility of initial convergence velocities that may differ in the two planes and allow for misalignment of the beam center-of-mass position and direction.

Anderson, O.A.

1996-06-01

436

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

437

47 CFR 51.711 - Symmetrical reciprocal compensation.  

Code of Federal Regulations, 2010 CFR

...Symmetrical reciprocal compensation. 51.711 Section...FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON...INTERCONNECTION Reciprocal Compensation for Transport and...Symmetrical reciprocal compensation. (a) Rates...incumbent LEC, a state commission shall establish...

2010-10-01

438

Linear IgA dermatosis induced by captopril  

Microsoft Academic Search

Summary Linear IgA dermatosis is an auto-immune bullous disease characterized by linear IgA deposition in the basement membrane. Most cases are idiopathic but some are drug-related. These lack mucosal involvement, have spontaneous remission and IgA deposition clearance at the basement membrane after drug cessation. A 89 year-old patient presenting with symmetric, itchy, tense and translucent bullous lesions located on the

N. Menezes

439

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

440

Multi-frequency EIT system with radially symmetric architecture: KHU Mark1.  

PubMed

We describe the development of a multi-frequency electrical impedance tomography (EIT) system (KHU Mark1) with a single balanced current source and multiple voltmeters. It was primarily designed for imaging brain function with a flexible strategy for addressing electrodes and a frequency range from 10 Hz-500 kHz. The maximal number of voltmeters is 64, and all of them can simultaneously acquire and demodulate voltage signals. Each voltmeter measures a differential voltage between a pair of electrodes. All voltmeters are configured in a radially symmetric architecture in order to optimize the routing of wires and minimize cross-talk. We adopted several techniques from existing EIT systems including digital waveform generation, a Howland current generator with a generalized impedance converter (GIC), digital phase-sensitive demodulation and tri-axial cables. New features of the KHU Mark1 system include multiple GIC circuits to maximize the output impedance of the current source at multiple frequencies. The voltmeter employs contact impedance measurements, data overflow detection, spike noise rejection, automatic gain control and programmable data averaging. The KHU Mark1 system measures both in-phase and quadrature components of trans-impedances. By using a script file describing an operating mode, the system setup can be easily changed. The performance of the developed multi-frequency EIT system was evaluated in terms of a common-mode rejection ratio, signal-to-noise ratio, linearity error and reciprocity error. Time-difference and frequency-difference images of a saline phantom with a banana object are presented showing a frequency-dependent complex conductivity of the banana. Future design of a more innovative system is suggested including miniaturization and wireless techniques. PMID:17664635

Oh, Tong In; Woo, Eung Je; Holder, David

2007-07-01

441

Symmetry, linear illusions, and the movements of the eye  

Microsoft Academic Search

Examines symmetrical forms, linear illusion, and validity of the Wundt-Lamansky law of eye-movements. Six Os were used to discover the most natural way of looking at figures. Results regarding the validity of the law indicate that in free movements of the eye, the rectus internus muscle is inclined to act, partly due to its relatively great size and strength, and

G. M. Stratton

1906-01-01

442

Tunneling control using classical non-linear oscillator  

SciTech Connect

A quantum particle is placed in symmetric double well potential which is coupled to a classical non-linear oscillator via a coupling function. With different spatial symmetry of the coupling and under various controlling fashions, the tunneling of the quantum particle can be enhanced or suppressed, or totally destroyed.

Kar, Susmita [Department of Physical Chemistry, Indian Association for the Cultivation of Science, Kolkata -700032 (India); Bhattacharyya, S. P., E-mail: pcspb@chem.iitb.ac.in [Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai- 400076 (India)

2014-04-24

443

Parametric device for symmetrization of three-phase potentials  

Microsoft Academic Search

The paper proposes a schematic design of a device for parametric symmetrization of three-phase potentials with simultaneous power supply from a three-phase network of single-phase and symmetric three-phase loads. The dependence of symmetric device parameters on the power transmission line impedance is computed, and it is shown that the effect of complete parametric symmetrization is not impaired by any changes

A. K. Shidlovskii; A. D. Muzychenko; I. V. Mostoviak; A. P. Trofimenko

1979-01-01

444

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

445

Honors question 3: Complex numbers (revisited). Arithmetic of complex numbers  

E-print Network

Honors question 3: Complex numbers (revisited). Arithmetic of complex numbers Recall that the complex numbers are formally defined as C = {a + bi} where a and b can be any real numbers and i is treated as a variable (so we can identify the complex numbers with the set of linear polynomials with real

Leininger, Christopher J.

446

Symmetrical factorization of the fast Fourier transform for efficient implementation  

Microsoft Academic Search

This paper shows a symmetrical decomposition of the Fast Fourier Transform (FFT) into stages such that butterflies of small radices can be applied efficiently. Due to symmetric, the bit reversal sorting is also symmetrical and allows semi in-place self-sorting to be carried out together with the butterfly processing at the middle stage. Furthermore, the mirroring effect due to the symmetry,

H. K. Sim

2004-01-01

447

DIRECTED CYCLIC HAMILTONIAN CYCLE SYSTEMS OF THE COMPLETE SYMMETRIC DIGRAPH  

E-print Network

DIRECTED CYCLIC HAMILTONIAN CYCLE SYSTEMS OF THE COMPLETE SYMMETRIC DIGRAPH HEATHER JORDON AND JOY symmetric digraph, K n, exist if and only if n 2 (mod 4) and n = 2p with p prime and 1. We also show that directed cyclic hamiltonian cycle systems of the complete symmetric digraph minus a set of n/2 vertex

Morris, Joy

448

Elliptical symmetric distribution based maximal margin classification for hyperspectral imagery  

Microsoft Academic Search

It has been verified that hyperspectral data is statistically characterized by elliptical symmetric distribution. Accordingly, we introduce the ellipsoidal discriminant boundaries and present an elliptical symmetric distribution based maximal margin (ESD-MM) classifier for hypespectral classification. In this method, the characteristic of elliptical symmetric distribution (ESD) of hyperspectral data is combined with the maximal margin rule. This strategy enables the ESD-MM

Lin He; Zhuliang Yu; Zhenghui Gu; Yuanqing Li

2011-01-01

449

A Berger type normal holonomy theorem for complex submanifolds  

Microsoft Academic Search

We prove a Berger type theorem for the normal holonomy group (i.e., the holonomy group of the normal connection) of a full complete complex submanifold of the complex projective space. Namely, if the normal holonomy does not act transitively, then the submanifold is the complex orbit, in the complex projective space, of the isotropy representation of an irreducible Hermitian symmetric

Sergio Console; Antonio J. Di Scala; Carlos Olmos

2008-01-01

450

Differential Complexes in Continuum Mechanics  

NASA Astrophysics Data System (ADS)

We study some differential complexes in continuum mechanics that involve both symmetric and non-symmetric second-order tensors. In particular, we show that the tensorial analogue of the standard grad-curl-div complex can simultaneously describe the kinematics and the kinetics of motion of a continuum. The relation between this complex and the de Rham complex allows one to readily derive the necessary and sufficient conditions for the compatibility of displacement gradient and the existence of stress functions on non-contractible bodies.We also derive the local compatibility equations in terms of the Green deformation tensor for motions of 2D and 3D bodies, and shells in curved ambient spaces with constant curvatures.

Angoshtari, Arzhang; Yavari, Arash

2015-04-01

451

Symmetrical Peripheral Gangrene Following Snake Bite  

PubMed Central

SPG (Symmetrical peripheral gangrene) is defined as symmetrical distal ischemic damage at two or more sites in the absence of large vessels obstruction. It has been ascribed to a number of infectious and non infectious conditions including connective tissue, cardiovascular, neoplastic and iatrogenic causes. We report a unique case of SPG in a 35-year-old Indian female who developed spontaneous gangrene of the distal phalanges of the right and left index, middle, ring and little fingers and the distal phalanges of all toes of the right and left foot following a snake bite. There have been very few cases of peripheral gangrene and acute renal failure associated with snake bite in literature. PMID:25386476

Shastri, Minal; Parikh, Mital; Patel, Dwijal; Chudasma, Ketan

2014-01-01

452

Symmetric scalar constraint for loop quantum gravity  

NASA Astrophysics Data System (ADS)

In the framework of loop quantum gravity, we define a new Hilbert space of states which are solutions of a large number of components of the diffeomorphism constraint. On this Hilbert space, using the methods of Thiemann, we obtain a family of gravitational scalar constraints. They preserve the Hilbert space for every choice of lapse function. Thus adjointness and commutator properties of the constraint can be investigated in a straightforward manner. We show how the space of solutions of the symmetrized constraint can be defined by spectral decomposition, and the Hilbert space of physical states by subsequently fully implementing the diffeomorphism constraint. The relationship of the solutions to those resulting from a proposal for a symmetric constraint operator by Thiemann remains to be elucidated.

Lewandowski, Jerzy; Sahlmann, Hanno

2015-02-01

453

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

454

Inertial defects of planar symmetric top molecules  

Microsoft Academic Search

A general expression for the inertial defects of planar symmetric top molecules has been derived and applied to H3+, CH3+, C3H3+, and C6H6-type molecules. It has been found that the inertial derivatives analphaalpha for these molecules can be expressed in terms of Coriolis constants. This allowed us to find a sufficient number of relations among Coriolis constants that the number

Mary-Frances Jagod; Takeshi Oka

1990-01-01

455

Symmetric voltage-controlled variable resistance  

NASA Technical Reports Server (NTRS)

Feedback network makes resistance of field-effect transistor (FET) same for current flowing in either direction. It combines control voltage with source and load voltages to give symmetric current/voltage characteristics. Since circuit produces same magnitude output voltage for current flowing in either direction, it introduces no offset in presense of altering polarity signals. It is therefore ideal for sensor and effector circuits in servocontrol systems.

Vanelli, J. C.

1978-01-01

456

Index-based symmetric DNA encryption algorithm  

Microsoft Academic Search

In this paper, a new index-based symmetric DNA encryption algorithm has been proposed. Adopting the methods of Block-Cipher and Index of string, the algorithm encrypts the DNA-sequence-based plaintext. First, the algorithm encodes each character into ASCII codes. And then, according to the nucleotide sequence, the researcher should convert it to the DNA coding. Besides, the researcher selects the special DNA

Zhang Yunpeng; Zhu Yu; Wang Zhong; Richard O. Sinnott

2011-01-01

457

Stabilization of Quantum Computations by Symmetrization  

Microsoft Academic Search

We propose a method for the stabilization of quantum computations (including quan- tum state storage). The method is based on the operation of projection intoSYM, the symmetric subspace of the full state space of R redundant copies of the computer. We describe an ecient algorithm and quantum network eectingSYM{projection and discuss the stabilizing eect of the proposed method in the

Adriano Barenco; Andre? Berthiaume; David Deutsch; Artur Ekert; Richard Jozsa; Chiara Macchiavello

1997-01-01

458

Peakedness and peakedness ordering in symmetric distributions  

Microsoft Academic Search

There are many ways to measure the dispersion of a random variable. One such method uses the concept of peakedness. If the random variable X is symmetric about a point ?, then Birnbaum [Z.W. Birnbaum, On random variables with comparable peakedness, The Annals of Mathematical Statistics 19 (1948) 76–81] defined the function P?(x)=P(|X??|?x),x?0, as the peakedness of X. If two

Hammou Elbarmi; Hari Mukerjee

2009-01-01

459

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

460

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

461

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

462

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

463

Nonthermal and geometric effects on the symmetric and anti-symmetric surface waves in a Lorentzian dusty plasma slab  

NASA Astrophysics Data System (ADS)

The nonthermal and geometric effects on the propagation of the surface dust acoustic waves are investigated in a Lorentzian dusty plasma slab. The symmetric and anti-symmetric dispersion modes of the dust acoustic waves are obtained by the plasma dielectric function with the spectral reflection conditions the slab geometry. The variation of the nonthermal and geometric effects on the symmetric and the anti-symmetric modes of the surface plasma waves is also discussed.

Lee, Myoung-Jae; Jung, Young-Dae

2015-02-01

464

Symmetric smoothing filters from global consistency constraints.  

PubMed

Many patch-based image denoising methods can be viewed as data-dependent smoothing filters that carry out a weighted averaging of similar pixels. It has recently been argued that these averaging filters can be improved using their doubly stochastic approximation, which are symmetric and stable smoothing operators. In this paper, we introduce a simple principle of consistency that argues that the relative similarities between pixels as imputed by the averaging matrix should be preserved in the filtered output. The resultant consistency filter has the theoretically desirable properties of being symmetric and stable, and is a generalized doubly stochastic matrix. In addition, we can also interpret our consistency filter as a specific form of Laplacian regularization. Thus, our approach unifies two strands of image denoising methods, i.e., symmetric smoothing filters and spectral graph theory. Our consistency filter provides high-quality image denoising and significantly outperforms the doubly stochastic version. We present a thorough analysis of the properties of our proposed consistency filter and compare its performance with that of other significant methods for image denoising in the literature. PMID:25532176

Haque, Sheikh Mohammadul; Pai, Gautam P; Govindu, Venu Madhav

2015-05-01

465

Universal horizons in maximally symmetric spaces  

E-print Network

Universal horizons in Ho\\v{r}ava-Lifshitz gravity and Einstein-{\\ae}ther theory are the equivalent of causal horizons in general relativity and appear to have many of the same properties, including a first law of horizon thermodynamics and thermal radiation. Since universal horizons are infrared solutions of a putative power counting renormalizable quantum gravitational theory, fully understanding their thermodynamics will shed light on the interplay between black hole thermodynamics and quantum gravity. In this paper, we provide a complete classification, including asymptotic charges, of all four dimensional static and spherically symmetric universal horizon solutions with maximally symmetric asymptotics -- the equivalents of the Schwarzschild, Schwarzschild de Sitter or Schwarzschild anti-de Sitter spacetimes. Additionally we derive the associated first laws for the universal horizon solutions. Finally we prove that independent of asymptotic boundary conditions, any spherically symmetric solution in Ho\\v{r}ava-Lifshitz gravity with a universal horizon is also a solution of Einstein-{\\ae}ther theory, thereby broadening and complementing the known equivalence region of the solution spaces.

Jishnu Bhattacharyya; David Mattingly

2014-08-27

466

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.

467

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

468

A Bayesian Approach to Empirical Local Linearization For Robotics   

E-print Network

Local linearizations are ubiquitous in the control of robotic systems. Analytical methods, if available, can be used to obtain the linearization, but in complex robotics systems where the dynamics and kinematics are ...

Ting, Jo-Anne; D'Souza, Aaron; Vijayakumar, Sethu; Schaal, Stefan

2008-01-01

469

Energy-momentum distribution of a general plane symmetric spacetime in metric f(R) gravity  

E-print Network

In this paper, the exact vacuum solution of a general plane symmetric spacetime is investigated in metric f(R) gravity with the assumption of constant Ricci scalar. For this solution, we have studied the generalized Landau-Lifshitz energy-momentum complex in this theory to determine the energy distribution expressions for some specific f(R) models. Also, we show that these models satisfy the constant curvature condition.

Morteza Yavari

2014-06-13

470

Robustness of linear quadratic state feedback designs in the presence of system uncertainty. [application to Augmentor Wing Jet STOL Research Aircraft flare control autopilot design  

NASA Technical Reports Server (NTRS)

The paper deals with the problem of expressing the robustness (stability) property of a linear quadratic state feedback (LQSF) design quantitatively in terms of bounds on the perturbations (modeling errors or parameter variations) in the system matrices so that the closed-loop system remains stable. Nonlinear time-varying and linear time-invariant perturbations are considered. The only computation required in obtaining a measure of the robustness of an LQSF design is to determine the eigenvalues of two symmetric matrices determined when solving the algebraic Riccati equation corresponding to the LQSF design problem. Results are applied to a complex dynamic system consisting of the flare control of a STOL aircraft. The design of the flare control is formulated as an LQSF tracking problem.

Patel, R. V.; Toda, M.; Sridhar, B.

1977-01-01

471

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

472

Hypothetical Datalog: Negation and Linear Recursion \\Lambda  

E-print Network

Hypothetical Datalog: Negation and Linear Recursion \\Lambda Anthony J. Bonner Department complexity. These restrictions are based on two ideas from Horn­clause logic: linear recursion and stratified negation. In particular, a notion of stratification is developed in which negation­as­failure alternates

Bonner, Anthony

473

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

474

Immunoblot Analysis of Linear Polyubiquitination of NEMO.  

PubMed

Stimulation with inflammatory cytokines such as TNF-? and IL-1 activates the canonical NF-?B pathway through the activation of the IKK complex. The mechanism underlying IKK activation has been extensively studied and the involvement of the ubiquitin system has been well documented. We have recently reported that a novel ubiquitin ligase complex, LUBAC is involved in the activation of the IKK complex. LUBAC consists of one catalytic subunit, HOIP and two accessory molecules, HOIL-1L and SHARPIN and activates the IKK complex by conjugating the linear polyubiquitin chains to NEMO (IKK?), the regulatory subunit of IKK complex. In this chapter, we describe the protocol for the detection of the linear polyubiquitination of NEMO by the immunoblotting using anti-linear ubiquitin antibody. PMID:25736756

Sasaki, Yoshiteru; Fujita, Hiroaki; Nakai, Misa; Iwai, Kazuhiro

2015-01-01

475

Gap solitons in PT-symmetric optical lattices with higher-order diffraction.  

PubMed

The existence and stability of gap solitons are investigated in the semi-infinite gap of a parity-time (PT)-symmetric periodic potential (optical lattice) with a higher-order diffraction. The Bloch bands and band gaps of this PT-symmetric optical lattice depend crucially on the coupling constant of the fourth-order diffraction, whereas the phase transition point of this PT optical lattice remains unchangeable. The fourth-order diffraction plays a significant role in destabilizing the propagation of dipole solitons. Specifically, when the fourth-order diffraction coupling constant increases, the stable region of the dipole solitons shrinks as new regions of instability appear. However, fundamental solitons are found to be always linearly stable with arbitrary positive value of the coupling constant. We also investigate nonlinear evolution of the PT solitons under perturbation. PMID:25606878

Ge, Lijuan; Shen, Ming; Ma, Chunlan; Zang, Taocheng; Dai, Lu

2014-12-01

476

Error reduction in retrievals of atmospheric species from symmetrically measured lidar sounding absorption spectra.  

PubMed

We report new methods for retrieving atmospheric constituents from symmetrically-measured lidar-sounding absorption spectra. The forward model accounts for laser line-center frequency noise and broadened line-shape, and is essentially linearized by linking estimated optical-depths to the mixing ratios. Errors from the spectral distortion and laser frequency drift are substantially reduced by averaging optical-depths at each pair of symmetric wavelength channels. Retrieval errors from measurement noise and model bias are analyzed parametrically and numerically for multiple atmospheric layers, to provide deeper insight. Errors from surface height and reflectance variations are reduced to tolerable levels by "averaging before log" with pulse-by-pulse ranging knowledge incorporated. PMID:25401639

Chen, Jeffrey R; Numata, Kenji; Wu, Stewart T

2014-10-20

477

Cutting Force Predication Based on Integration of Symmetric Fuzzy Number and Finite Element Method  

PubMed Central

In the process of turning, pointing at the uncertain phenomenon of cutting which is caused by the disturbance of random factors, for determining the uncertain scope of cutting force, the integrated symmetric fuzzy number and the finite element method (FEM) are used in the prediction of cutting force. The method used symmetric fuzzy number to establish fuzzy function between cutting force and three factors and obtained the uncertain interval of cutting force by linear programming. At the same time, the change curve of cutting force with time was directly simulated by using thermal-mechanical coupling FEM; also the nonuniform stress field and temperature distribution of workpiece, tool, and chip under the action of thermal-mechanical coupling were simulated. The experimental result shows that the method is effective for the uncertain prediction of cutting force. PMID:24790556

Wang, Zhanli; Hu, Yanjuan; Wang, Yao; Dong, Chao; Pang, Zaixiang

2014-01-01

478

Three-Dimensional Solutions for Contact Area in Laminated Composite Pinned Joints with Symmetric and Non-Symmetric Stacking Sequences  

NASA Astrophysics Data System (ADS)

The aim of this study is computing and evaluating the behavior of the laminated composite plate at the contact area in single lap, mechanically fastened joints. The analyses involve three dimensional finite element models performed by ABAQUS 6.4-PR11 code to evaluate the stress distribution in contact surface, separation angle, the magnitude and location of maximum radial stress. Results are determined for composite laminates with different layer configurations and attempts are made to validate the models with previous works. For cross ply and angle ply configurations only symmetric stacking sequences are used while for quasi-isotropic laminate both symmetric and non-symmetric models are generated. In cross-ply laminate symmetric separation about bearing plane could be found while in quasi-isotropic and angle-ply laminates non-symmetric separation occurs. Also, the separation angle is less than 90° in symmetric laminates and greater than 90° in some plies of non-symmetric laminates.

Javadi, H.; Rajabi, I.; Yavari, V.; Kadivar, M. H.

479

Symmetrical and anti-symmetrical coherent perfect absorption for acoustic waves  

SciTech Connect

We investigate tunable acoustic absorption enabled by the coherent control of input waves. It relies on coherent perfect absorption originally proposed in optics. By designing appropriate acoustic metamaterial structures with resonating effective bulk modulus or density, we show that complete absorption of incident waves impinging on the metamaterial can be achieved for either symmetrical or anti-symmetrical inputs in the forward and backward directions. By adjusting the relative phase between the two incident beams, absorption can be tuned effectively from unity to zero, making coherent control useful in applications like acoustic modulators, noise controllers, transducers, and switches.

Wei, Pengjiang; Croënne, Charles; Tak Chu, Sai [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Li, Jensen, E-mail: j.li@bham.ac.uk [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom)

2014-03-24

480

Symmetry-restrained flexible fitting for symmetric EM maps.  

PubMed

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

2011-09-01

481

Three-Dimensional Structures of the Spatiotemporal Nonlinear Schrödinger Equation with Power-Law Nonlinearity in PT-Symmetric Potentials  

PubMed Central

The spatiotemporal nonlinear Schrödinger equation with power-law nonlinearity in -symmetric potentials is investigated, and two families of analytical three-dimensional spatiotemporal structure solutions are obtained. The stability of these solutions is tested by the linear stability analysis and the direct numerical simulation. Results indicate that solutions are stable below some thresholds for the imaginary part of -symmetric potentials in the self-focusing medium, while they are always unstable for all parameters in the self-defocusing medium. Moreover, some dynamical properties of these solutions are discussed, such as the phase switch, power and transverse power-flow density. The span of phase switch gradually enlarges with the decrease of the competing parameter k in -symmetric potentials. The power and power-flow density are all positive, which implies that the power flow and exchange from the gain toward the loss domains in the cell. PMID:24983624

Dai, Chao-Qing; Wang, Yan

2014-01-01

482

Supersymmetric model of a Bose-Einstein condensate in a $\\mathcal{PT}$-symmetric double-delta trap  

E-print Network

The most important properties of a Bose-Einstein condensate subject to balanced gain and loss can be modelled by a Gross-Pitaevskii equation with an external $\\mathcal{PT}$-symmetric double-delta potential. We study its linear variant with a supersymmetric extension. It is shown that both in the $\\mathcal{PT}$-symmetric as well as in the $\\mathcal{PT}$-broken phase arbitrary stationary states can be removed in a supersymmetric partner potential without changing the energy eigenvalues of the other state. The characteristic structure of the singular delta potential in the supersymmetry formalism is discussed, and the applicability of the formalism to the nonlinear Gross-Pitaevskii equation is analysed. In the latter case the formalism could be used to remove $\\mathcal{PT}$-broken states introducing an instability to the stationary $\\mathcal{PT}$-symmetric states.

Nikolas Abt; Holger Cartarius; Günter Wunner

2014-12-24

483

Finite Neutrosophic Complex Numbers  

E-print Network

In this book for the first time the authors introduce the notion of real neutrosophic complex numbers. Further the new notion of finite complex modulo integers is defined. For every $C(Z_n)$ the complex modulo integer $i_F$ is such that $2F_i = n - 1$. Several algebraic structures on $C(Z_n)$ are introduced and studied. Further the notion of complex neutrosophic modulo integers is introduced. Vector spaces and linear algebras are constructed using these neutrosophic complex modulo integers.

W. B. Vasantha Kandasamy; Florentin Smarandache

2011-11-01

484

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

485