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1

Linearization Method and Linear Complexity  

NASA Astrophysics Data System (ADS)

We focus on the relationship between the linearization method and linear complexity and show that the linearization method is another effective technique for calculating linear complexity. We analyze its effectiveness by comparing with the logic circuit method. We compare the relevant conditions and necessary computational cost with those of the Berlekamp-Massey algorithm and the Games-Chan algorithm. The significant property of a linearization method is that it needs no output sequence from a pseudo-random number generator (PRNG) because it calculates linear complexity using the algebraic expression of its algorithm. When a PRNG has n [bit] stages (registers or internal states), the necessary computational cost is smaller than O(2n). On the other hand, the Berlekamp-Massey algorithm needs O(N2) where N(?2n) denotes period. Since existing methods calculate using the output sequence, an initial value of PRNG influences a resultant value of linear complexity. Therefore, a linear complexity is generally given as an estimate value. On the other hand, a linearization method calculates from an algorithm of PRNG, it can determine the lower bound of linear complexity.

Tanaka, Hidema

2

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

3

Conservation Properties of Symmetric BVMs Applied to Linear Hamiltonian Problems  

Microsoft Academic Search

We consider the application of symmetric Boundary Value Methods to linear autonomous Hamiltonian systems. The numerical approximation\\u000a of the Hamiltonian function exhibits a superconvergence property, namely its order of convergence is p + 2 for a p order symmetric method. We exploit this result to define a natural projection procedure that slightly modifies the numerical\\u000a solution so that, without changing

Pierluigi Amodio; Felice Iavernaro; Donato Trigiante

2002-01-01

4

Complex PT-symmetric nonlinear Schrödinger equation and Burgers equation.  

PubMed

The complex -symmetric nonlinear wave models have drawn much attention in recent years since the complex -symmetric extensions of the Korteweg-de Vries (KdV) equation were presented in 2007. In this review, we focus on the study of the complex -symmetric nonlinear Schrödinger equation and Burgers equation. First of all, we briefly introduce the basic property of complex symmetry. We then report on exact solutions of one- and two-dimensional nonlinear Schrödinger equations (known as the Gross-Pitaevskii equation in Bose-Einstein condensates) with several complex -symmetric potentials. Finally, some complex -symmetric extension principles are used to generate some complex -symmetric nonlinear wave equations starting from both -symmetric (e.g. the KdV equation) and non- -symmetric (e.g. the Burgers equation) nonlinear wave equations. In particular, we discuss exact solutions of some representative ones of the complex -symmetric Burgers equation in detail. PMID:23509385

Yan, Zhenya

2013-03-18

5

Computational competition of symmetric mixed FEM in linear elasticity  

Microsoft Academic Search

The Navier–Lamé equation for linear elasticity has evoked the design of various non-standard finite element methods (FEM) in order to overcome the locking phenomenon. Recent developments of Arnold and Winther in 2002 involve a stable mixed method which strongly fulfils the symmetry constraint. Subsequently, two H(div) non-conforming symmetric mixed methods arose. This paper comments on the implementation of all those

C. Carstensen; M. Eigel; J. Gedicke

2011-01-01

6

A Generalized Conjugate Gradient Method for Non-Symmetric Systems of Linear Equations.  

National Technical Information Service (NTIS)

A new iterative method is presented for solving non-symmetric linear systems of equations. The method requires that the symmetric of the matrix of the linear system be positive definite, and the method is efficient only if the symmetric part is easily inv...

J. C. Strikwerda

1981-01-01

7

Mode Classification of Linear Adiabatic Oscillations of Spherically Symmetric Stars  

NASA Astrophysics Data System (ADS)

We propose a mathematical scheme to classify the eigenmodes of linear adiabatic oscillations of spherically symmetric stars, while fully taking account of the perturbation to the gravitational potential. The scheme allows us to allocate a unique and continuous integral index (the radial order) to each non-degenerate eigenmode with a positive squared eigenfrequency of any stellar structure, whereas a pair of degenerate eigenmodes, if exist, are assigned a unique pair of indices. The indices of the eigenmodes are invariant against any continuous change in the equilibrium structure. Based on these indices, we can unambiguously define the three kinds of eigenmodes of adiabatic stellar oscillations: p-modes, g-modes, and f-modes.

Takata, Masao

2012-08-01

8

Parallel gradient projection successive overrelaxation for symmetric linear complementarity problems and linear programs  

SciTech Connect

Gradient projection successive overrelaxation (GP-SOR) algorithm is proposed for the solution of symmetric linear complementarity problems and linear programs. A key distinguishing feature of this algorithm is that when appropriately parallelized, the relaxation factor interval (0,2) is not reduced. In a previously proposed parallel SOR schemes the substantially reduced relaxation interval mandated by the coupling terms of the problem often led to slow convergence. The proposed parallel algorithms are applied to finding the least 2-norm solution of linear programs. Efficiency of the algorithm is in the 50 to 100 percent range as demonstrated by computational results on the CRYSTAL token-ring multicomputer and the Sequent Balance 21000 multiprocessor.

Mangasarian, O.L.; DeLeone, R.

1986-01-01

9

Quantum communication complexity of symmetric predicates  

Microsoft Academic Search

We completely (that is, up to a logarithmic factor) characterize the bounded-error quantum communication complexity of every predicate f(x,y) x,y\\\\subseteq \\\\lbrack n \\\\rbrack ) depending only on \\\\vert x\\\\cap y\\\\vert. More precisely, given a predicate D on \\\\{0,1,\\\\dots,n\\\\}, we put \\\\displaystyle \\\\ell_0(D)\\\\displaystyle \\\\overset{\\\\mathrm{def}}{=}\\\\max\\\\{\\\\ell\\\\mid 1\\\\leqslant\\\\ell\\\\leqslant n\\/2\\\\land D(\\\\ell)\\\

A. A. Razborov

2003-01-01

10

Quantum communication complexity of symmetric predicates  

Microsoft Academic Search

We completely (that is, up to a logarithmic factor) characterize the\\u000abounded-error quantum communication complexity of every predicate $f(x,y)$\\u000adepending only on $|x\\\\cap y|$ ($x,y\\\\subseteq [n]$). Namely, for a predicate $D$\\u000aon $\\\\{0,1,...,n\\\\}$ let $\\\\ell_0(D)\\\\df \\\\max\\\\{\\\\ell : 1\\\\leq\\\\ell\\\\leq n\\/2\\\\land\\u000aD(\\\\ell)\\\

Alexander A. Razborov

2002-01-01

11

Local bifurcation in symmetric coupled cell networks: Linear theory  

Microsoft Academic Search

We consider a coupled cell network of differential equations with finite symmetry group ?, where ? permutes cells transitively. We show how the structure of the coupled cell network, represented by a directed graph whose vertices represent individual cells and edges represent couplings, can be taken into account in the bifurcation analysis of a fully symmetric steady-state solution.We focus on

Ana Paula S. Dias; Jeroen S. W. Lamb

2006-01-01

12

Linear and nonlinear parity-time-symmetric oligomers: a dynamical systems analysis.  

PubMed

In the present work, we focus on the cases of two-site (dimer) and three-site (trimer) configurations, i.e. oligomers, respecting the parity-time (PT) symmetry, i.e. with a spatially odd gain-loss profile. We examine different types of solutions of such configurations with linear and nonlinear gain/loss profiles. Solutions beyond the linear PT-symmetry critical point as well as solutions with asymmetric linearization eigenvalues are found in both the nonlinear dimer and trimer. The latter feature is absent in linear PT-symmetric trimers, while both of them are absent in linear PT-symmetric dimers. Furthermore, nonlinear gain/loss terms enable the existence of both symmetric and asymmetric solution profiles (and of bifurcations between them), while only symmetric solutions are present in the linear PT-symmetric dimers and trimers. The linear stability analysis around the obtained solutions is discussed and their dynamical evolution is explored by means of direct numerical simulations. Finally, a brief discussion is also given of recent progress in the context of PT-symmetric quadrimers. PMID:23509388

Duanmu, M; Li, K; Horne, R L; Kevrekidis, P G; Whitaker, N

2013-03-18

13

Light-heavy quark-type linear potential models with spin- and pseudospin-symmetric states  

NASA Astrophysics Data System (ADS)

Possible spin- and pseudospin-symmetric states with positive energies of the Dirac equation with linear scalar and vector potentials are investigated. Two exact relativistic spin symmetries of linear quark-type potential models are shown to exist for positive energies. It is known that positive-energy states which still exist in the non-relativistic limit are always of the spin-symmetric type, like those described in the Schrödinger framework. However, if significant relativistic corrections to the Schrödinger theory are considered and also different possible signs of vector and scalar potentials, there exist two exact spin symmetries: a spin-symmetric energy spectrum that tends to the previously known spectrum obtained by the Schrödinger theory in the non-relativistic limit, and a pseudospin-symmetric energy spectrum that does not. The exact symmetries are perturbed by modifying the strengths of the relativistic linear vector and scalar potentials and introducing a tensor coupling. These perturbations may cancel each other.

Thylwe, Karl-Erik; Hamzavi, Majid

2013-03-01

14

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

15

Stationary modes and integrals of motion in nonlinear lattices with a { {PT}}-symmetric linear part  

NASA Astrophysics Data System (ADS)

We consider finite-dimensional nonlinear systems with a linear part described by a parity-time ({ {PT}}-)symmetric operator. We investigate bifurcations of stationary nonlinear modes from the eigenstates of the linear operator and consider a class of { {PT}}-symmetric nonlinearities allowing the existence of families of nonlinear modes. We pay particular attention to situations when the underlying linear { {PT}}-symmetric operator is characterized by the presence of degenerate eigenvalues or an exceptional-point singularity. In each of the cases we construct formal expansions for small-amplitude nonlinear modes. We also report a class of nonlinearities allowing the system to admit one or several integrals of motion, which turn out to be determined by the pseudo-hermiticity of the nonlinear operator.

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

2013-10-01

16

Plane symmetric gravitational collapse and linear equation of state  

NASA Astrophysics Data System (ADS)

This paper examines the gravitational collapse in plane symmetry with a perfect fluid using a linear equation of state p= k?. We find a class of collapse models satisfying the Einstein field equations and also the regularity as well as energy conditions. For a given initial data, the outcome of the collapse turns out to be a black membrane or a naked singularity depending upon the equation of state parameter. We conclude that this parameter plays a crucial role in determining the final fate of the collapse.

Sharif, M.; Majid, Amal

2013-09-01

17

Solitons supported by complex PT-symmetric Gaussian potentials  

SciTech Connect

The existence and stability of fundamental, dipole, and tripole solitons in Kerr nonlinear media with parity-time-symmetric Gaussian complex potentials are reported. Fundamental solitons are stable not only in deep potentials but also in shallow potentials. Dipole and tripole solitons are stable only in deep potentials, and tripole solitons are stable in deeper potentials than for dipole solitons. The stable regions of solitons increase with increasing potential depth. The power of solitons increases with increasing propagation constant or decreasing modulation depth of the potentials.

Hu Sumei [Laboratory of Photonic Information Technology, South China Normal University, Guangzhou 510631 (China); Department of Physics, Guangdong University of Petrochemical Technology, Maoming 525000 (China); Ma Xuekai; Lu Daquan; Yang Zhenjun; Zheng Yizhou; Hu Wei [Laboratory of Photonic Information Technology, South China Normal University, Guangzhou 510631 (China)

2011-10-15

18

Symmetric linear functions of the restricted quantum group $\\\\bar{U}_qsl_2(\\\\mathbb{C})$  

Microsoft Academic Search

We determine a set of primitive idempotents and the basic algebra of the restricted quantum group $\\\\bar{U}_qsl_2(\\\\mathbb{C})$. As a result, we can show the dimension of the space of symmetric linear functions of $\\\\bar{U}_qsl_2(\\\\mathbb{C})$ is $3p-1$

Yusuke Arike

2007-01-01

19

On the Lanczos method for solving symmetric linear systems with several right-hand sides  

Microsoft Academic Search

This paper analyzes a few methods based on the Lanczos algorithm for solving large sparse symmetric linear systems with several right-hand sides. The methods examined are suitable for the situation when the right sides are not too different from one another, as is often the case in time-dependent or parameter-dependent problems. We propose a theoretical error bound for the approximation

Youcef Saad

1987-01-01

20

Generation and detection of linearly polarized axially symmetric beam by an amplitude computer-generated hologram  

NASA Astrophysics Data System (ADS)

A novel beam combination scheme was proposed to generate high order linearly polarized axially symmetric beam (LPASB) by superposing two Laguerre-Gaussian (LG) beams with opposite azimuthal quantum numbers. An amplitude computer-generated hologram (CGH) was not only used to generate two LG beams but also used in the combination scheme. Amplitude CGH was also used to detect the order of the LPASB.

Xin, Jingtao; Gao, Chunqing; Wang, Zheng; Chen, Li; Zhang, Qian; Wang, Zhengyong

2012-08-01

21

On the Computational Complexity of Binary and Analog Symmetric Hopfield Nets  

Microsoft Academic Search

We investigate the computational properties of finite binary- and analog-state discrete-time symmetric Hopfield nets. For binary networks, we obtain a simulation of convergent asymmetric networks by symmetric networks with only a linear increase in network size and computation time. Then we analyze the convergence time of Hopfield nets in terms of the length of their bit representations. Here we construct

Ji?í Šíma; Pekka Orponen; Teemu Antti-Poika

2000-01-01

22

Duality for symmetric second rank tensors. II. The linearized gravitational field  

NASA Astrophysics Data System (ADS)

The construction of dual theories for linearized gravity in four dimensions is considered. Our approach is based on the parent Lagrangian method previously developed for the massive spin-two case, but now considered for the zero mass case. This leads to a dual theory described in terms of a rank two symmetric tensor, analogous to the usual gravitational field, and an auxiliary antisymmetric field. This theory has an enlarged gauge symmetry, but with an adequate partial gauge fixing it can be reduced to a gauge symmetry similar to the standard one of linearized gravitation. We present examples illustrating the general procedure and the physical interpretation of the dual fields. The zero mass case of the massive theory dual to the massive spin-two theory is also examined, but we show that it only contains a spin-zero excitation.

Casini, H.; Montemayor, R.; Urrutia, Luis F.

2003-09-01

23

Lattice solitons in optical media described by the complex Ginzburg-Landau model with PT-symmetric periodic potentials  

NASA Astrophysics Data System (ADS)

We report the existence, stability, and rich dynamics of dissipative lattice solitons in optical media described by the cubic-quintic complex Ginzburg-Landau model with parity-time (PT) symmetric potentials. We focus on studying the generic spatial soliton propagation scenarios by changing (a) the linear loss coefficient in the complex Ginzburg-Landau model, (b) the amplitudes, and (c) the periods of real and imaginary parts of the complex-valued PT-symmetric optical lattice potential. Generically, it is found that if the period of the real part of the PT-symmetric optical lattice potential is close to ?, the spatial solitons are tightly bound and they can propagate straightly along the lattice, while if the period of the real part of the PT-symmetric optical lattice potential is larger than ?, the launched solitons are loosely bound and they can exhibit either a transverse (lateral) drift or a persistent swing around the input launching point due to gradient force arising from the spatially inhomogeneous loss. These latter features are intimately related to the dissipative nature of the system under consideration because they do not arise in the conservative counterpart of the dynamical model. These generic propagation scenarios can be effectively managed by properly changing the profile of the spatially inhomogeneous loss.

He, Yingji; Mihalache, Dumitru

2013-01-01

24

Complex bodies with memory: Linearized setting  

Microsoft Academic Search

The mechanics of complex bodies with memory effects is discussed in linearized setting. The attention is focused on the characterization of free energies in terms of minimum work and maximum recoverable work in the bulk and along a discontinuity surface endowed with its own surface energy, a surface internal to the body. To this aim, use is made of techniques

Paolo Maria Mariano; Paolo Paoletti

2009-01-01

25

Realization of Critical Eigenvalues for Scalar and Symmetric Linear Delay-Differential Equations  

NASA Astrophysics Data System (ADS)

This paper studies the link between the number of critical eigenvalues and the number of delays in certain classes of delay-differential equations. There are two main results. The first states that for k purely imaginary numbers which are linearly independent over the rationals, there exists a scalar delay-differential equation depending on k fixed delays whose spectrum contains those k purely imaginary numbers. The second result is a generalization of the first result for delay-differential equations which admit a characteristic equation consisting of a product of s factors of scalar type. In the second result, the k eigenvalues can be distributed amongst the different factors. Since the characteristic equation of scalar equations contain only exponential terms, the proof exploits a toroidal structure which comes from the arguments of the exponential terms in the characteristic equation. Our second result is applied to delay coupled D_n-symmetric cell systems with one-dimensional cells. In particular, we provide a general characterization of delay coupled D_n-symmetric systems with arbitrary number of delays and cell dimension.

Buono, P. L.; Leblanc, V. G.

2008-01-01

26

An efficient EM-ICP algorithm for symmetric consistent non-linear registration of point sets  

PubMed Central

In this paper, we present a new algorithm for non-linear registration of point sets. We estimate both forward and backward deformations fields best superposing the two point sets of interest and we make sure that they are consistent with each other by designing a symmetric cost function where they are coupled. Regularisation terms are included in this cost function to enforce deformation smoothness. Then we present a two-step iterative algorithm to optimise this cost function, where the two fields and the fuzzy matches between the two sets are estimated in turn. Building regularisers using the RKHS theory allows to obtain fast and efficient closed-form solutions for the optimal fields. The resulting algorithm is efficient and can deal with large point sets.

Combes, Benoit; Prima, Sylvain

2010-01-01

27

Interval linear systems with symmetric matrices, skew-symmetric matrices and dependencies in the right hand side  

Microsoft Academic Search

The methods of Interval Arithmetic permit to calculate guaranteed a posteriori bounds for the solution set of problems with interval input data. At present, these methods assume that all input data vary independently between their given lower and upper bounds. This paper shows for special interval linear systems how to handle the case where dependencies of the input data occur.

C. Jansson

1991-01-01

28

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

SciTech Connect

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

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

2010-08-15

29

Symmetric topological complexity of projective and lens spaces  

Microsoft Academic Search

For real projective spaces, (a) the Euclidean immersion dimension, (b) the\\u000aexistence of axial maps, and (c) the topological complexity are known to be\\u000athree facets of the same problem. But when it comes to embedding dimension, the\\u000aclassical work of Berrick, Feder and Gitler leaves a small indeterminacy when\\u000atrying to identify the existence of Euclidean embeddings of these

Jesus Gonzalez; Peter Landweber

2009-01-01

30

Preconditioning the bidomain model with almost linear complexity  

NASA Astrophysics Data System (ADS)

The bidomain model is widely used in electro-cardiology to simulate spreading of excitation in the myocardium and electrocardiograms. It consists of a system of two parabolic reaction diffusion equations coupled with an ODE system. Its discretisation displays an ill-conditioned system matrix to be inverted at each time step: simulations based on the bidomain model therefore are associated with high computational costs. In this paper we propose a preconditioning for the bidomain model either for an isolated heart or in an extended framework including a coupling with the surrounding tissues (the torso). The preconditioning is based on a formulation of the discrete problem that is shown to be symmetric positive semi-definite. A block LU decomposition of the system together with a heuristic approximation (referred to as the monodomain approximation) are the key ingredients for the preconditioning definition. Numerical results are provided for two test cases: a 2D test case on a realistic slice of the thorax based on a segmented heart medical image geometry, a 3D test case involving a small cubic slab of tissue with orthotropic anisotropy. The analysis of the resulting computational cost (both in terms of CPU time and of iteration number) shows an almost linear complexity with the problem size, i.e. of type nlog?(n) (for some constant ?) which is optimal complexity for such problems.

Pierre, Charles

2012-01-01

31

Iterative methods for complex symmetric systems with multiple right-hand sides  

Microsoft Academic Search

. The aim of this paper is to introduce and analyze block and nonblock iterative methods to solveA[x(1); : : : ; x(s)] = [b(1); : : : ; b(s)], where A is complex symmetric. The block methods are based on short termrecurrences combined with quasi-minimization of the residual. The inner iteration of the nonblock method appliesone residual polynomial to

V. Simoncini; E. Gallopoulos

1994-01-01

32

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

SciTech Connect

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

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

2010-09-30

33

A hybrid preconditioner of banded matrix approximation and alternating direction implicit iteration for symmetric Sinc–Galerkin linear systems  

Microsoft Academic Search

The symmetric Sinc–Galerkin method applied to a sparable second-order self-adjoint elliptic boundary value problem gives rise to a system of linear equations(?x?Dy+Dx??y)u=g,where? is the Kronecker product symbol, ?x and ?y are Toeplitz-plus-diagonal matrices, and Dx and Dy are diagonal matrices. The main contribution of this paper is to present and analyze a two-step preconditioning strategy based on the banded matrix

Michael K. Ng; Zhong-Zhi Bai

2003-01-01

34

Quasi-static and nonquasi-static compact MOSFET models based on symmetric linearization of the bulk and inversion charges  

Microsoft Academic Search

A particularly simple form of the charge-sheet model (CSM) is developed using symmetric linearization of the bulk charge as a function of the surface potential. The new formulation is verified by comparison with the original form of the CSM and is used to obtain a simple and accurate expressions for the quasi-static (QS) terminal charges based on the Ward-Dutton partition.

Hailing Wang; Ten-Lon Chen; Gennady Gildenblat

2003-01-01

35

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

PubMed

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

Serbes, G; Aydin, N

2011-01-01

36

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

SciTech Connect

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

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

2004-06-01

37

Grain Rotation in Ion-Complexed Symmetric Diblock Copolymer Thin Films under an Electric Field  

SciTech Connect

In symmetric polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer thin films, lithium-PMMA complexes were formed with the addition of lithium chloride (LiCl), significantly increasing both {chi} and dielectric constant. These led to a transition in the kinetic pathway of the orientation of lamellar microdomains under an applied electric field from a disruption and re-formation of the microdomains to a grain rotation mediated by movement of defects. By controlling the number of lithium-PMMA complexes, the microdomain alignment is possibly regulated in PS-b-PMMA copolymer thin films.

Wang,J.; Leiston-Belanger, J.; Sievert, J.; Russell, T.

2006-01-01

38

Reciprocity and unitarity in scattering from a non-Hermitian complex PT-symmetric potential  

NASA Astrophysics Data System (ADS)

In quantum scattering, Hermiticity is necessary for both reciprocity and unitarity. Reciprocity means that both reflectivity (R) and transmitivity (T) are insensitive to the direction of incidence of a wave (particle) at a scatterer from left/right. Unitarity means that R+T=1. In scattering from non-Hermitian PT-symmetric structures the (left/right) handedness (non-reciprocity) of reflectivity is known to be essential and unitarity remains elusive so far. Here we present a surprising occurrence of both reciprocity and unitarity in some parametric regimes of scattering from a complex PT-symmetric potential. In special cases, we show that this potential can even become invisible (R=0, T=1) remarkably this time from both left and right sides. We also find that this potential in a parametric regime enjoys a pseudo-unitarity of the type: T+RR=1.

Ahmed, Zafar

2013-05-01

39

Structural tailoring effects on the magnetic behavior of symmetric and asymmetric cubane-type Ni complexes.  

PubMed

Using two kinds of carboxylate ligands with small but significant differences in steric size, symmetric and asymmetric Fe(II) and Ni(II) cubanes have been synthesized in a controlled fashion. Fast sweeping pulsed field measurements showed magnetization hysteresis loops for two cubane-type molecular complexes, [Ni4(?-OMe)4(O2CAr(4F-Ph))4(HOMe)8] and [Ni4(?-OMe)4(O2CAr(Tol))4(HOMe)6], thus suggesting single-molecule magnet behavior. To differentiate the magnetic properties between the symmetric and asymmetric cubanes, detailed electron paramagnetic resonance (EPR) measurements were performed. From the EPR data, taken at various frequencies and temperatures, zero-field splitting parameters D, E, and other higher-order parameters for both cubane samples were extracted. Compared to the symmetric Ni-cubane, the asymmetric one shows an increase in the D and E values by about 20%, thereby suggesting structural engineering effects on the magnetic properties. By using the magnetic parameters determined by EPR, a static magnetization curve at 2?K and a temperature dependence of the magnetic susceptibility were simulated. A good agreement between theoretical and experimental data confirms the validity of the values obtained from EPR measurements. PMID:23509044

Ponomaryov, Alexey N; Kim, Namseok; Hwang, Jaewon; Nojiri, Hiroyuki; van Tol, Johan; Ozarowski, Andrew; Park, Jena; Jang, Zeehoon; Suh, Byoungjin; Yoon, Sungho; Choi, Kwang-Yong

2013-03-18

40

GEOMETRICALLY NON-LINEAR FREE VIBRATION OF FULLY CLAMPED SYMMETRICALLY LAMINATED RECTANGULAR COMPOSITE PLATES  

Microsoft Academic Search

The geometrically non-linear free vibration of thin composite laminated plates is investigated by using a theoretical model based on Hamilton's principle and spectral analysis previously applied to obtain the non-linear mode shapes and resonance frequencies of thin straight structures, such as beams, plates and shells (Benamar et al. 1991Journal of Sound and Vibration149 , 179–195; 1993, 164, 295–316; 1990 Proceedings

B. Harras; R. Benamar; R. G. WHITE

2002-01-01

41

A symmetrical tetramer for S. aureus pyruvate carboxylase in complex with coenzyme A  

PubMed Central

Pyruvate carboxylase (PC) is a conserved metabolic enzyme with important cellular functions. We report here crystallographic and cryoEM studies of S. aureus PC (SaPC) in complex with acetyl-CoA, an allosteric activator, as well as 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 may 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 cryoEM studies confirm the symmetrical nature of the tetramer. These observations are in sharp contrast to the highly asymmetrical tetramer of R. 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 may be catalytically more competent.

Yu, Linda P. C.; Xiang, Song; Lasso, Gorka; Gil, David; Valle, Mikel; Tong, Liang

2009-01-01

42

Deterministic self-similar models of complex networks based on very symmetric graphs  

NASA Astrophysics Data System (ADS)

Using very symmetric graphs we generalize several deterministic self-similar models of complex networks and we calculate the main network parameters of our generalization. More specifically, we calculate the order, size and the degree distribution, and we give an upper bound for the diameter and a lower bound for the clustering coefficient. These results yield conditions under which the network is a self-similar and scale-free small world network. We remark that all these conditions are posed on a small base graph which is used in the construction. As a consequence, we can construct complex networks having prescribed properties. We demonstrate this fact on the clustering coefficient. We propose eight new infinite classes of complex networks. One of these new classes is so rich that it is parametrized by three independent parameters.

Knor, Martin; Škrekovski, Riste

2013-10-01

43

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

NASA Astrophysics Data System (ADS)

It is well known that the two-dimensional (2D) nonlinear Schrödinger 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 have not been 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 unstable at a point of the direct bifurcation, which is followed, at larger values of the energy, by the reverse bifurcation restabilizing the symmetric solitons. However, on the contrary to the 1D system, both the direct and reverse bifurcation may be of the subcritical type, at sufficiently small values of the coupling constant, ?. Thus, the system demonstrates a double bistabilityfor the fundamental solitons. The stability of the solitons is investigated via the computation of instability growth rates for small perturbations. Vortex rings, which we study for two values of the “spin”, s=1 and 2, may be subject to the azimuthal instability, like in the single-component model. In particular, complete destabilization of asymmetric vortices is demonstrated for a sufficiently strong linear coupling. With the decrease of ?, a region of stable asymmetric vortices appears, and a single region of bistability for the vortices is found. We also develop a quasi-analytical approach to the description of the bifurcations diagrams, based on the variational approximation. Splitting of asymmetric vortices, induced by the azimuthal instability, is studied by means of direct simulations. Interactions between initially quiescent solitons of different types are studied too. In particular, we confirm the prediction of the reversal of the sign of the interaction (attractive/repulsive for in-phase/out-of-phase pairs) for the solitons with the odd spin, s=1, in comparison with the even values, s=0and 2.

Dror, Nir; Malomed, Boris A.

2011-03-01

44

Hybrid Logics on Linear Structures: Expressivity and Complexity  

Microsoft Academic Search

We investigate expressivity and complexity of hybrid log- ics on linear structures. Hybrid logics are an enrichment of modal logics with certain first-order features which are al- gorithmically well behaved. Therefore, they are well suited for the specification of certain properties of computational systems. We show that hybrid logics are more expressive than usual modal and temporal logics on linear

Massimo Franceschet; Maarten De Rijke; Bernd-holger Schlingloff

2003-01-01

45

A C3 Symmetric Nitrate Complex with a Thiophene-Based Tripodal Receptor  

PubMed Central

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 C3 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. 1H 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.

Isiklan, Muhammet; Saeed, Musabbir A.; Pramanik, Avijit; Wong, Bryan M.; Fronczek, Frank R.; Hossain, Alamgir

2011-01-01

46

New Fast Hartley Transform with Linear Multiplicative Complexity  

Microsoft Academic Search

In this paper, we introduced a new Hartley transform algorithm with linear multiplicative complexity. The proposed algorithm not only minimizes the number of multiplications, but also reduces the total number of operations (arithmetic complexity, or the number of multiplications and additions) compared to the existing and recently published methods, such as Heideman, Burrus, Bi et al., Bouguezel et al. (3-10,

Sos S. Agaian; Okan Caglayan

2006-01-01

47

Classification topologie des systemes lineaires complexes. (Topological classification of complex linear systems).  

National Technical Information Service (NTIS)

In this paper we show that a complex linear system (Sigma)(A,B) : dx/dz = Ax + Bu, z is a an element of C is linearly equivalent to a canonical direct product of the simple linear systems. After, we prove that two systems are topologically equivalent (r r...

Nguyen Huynh Phan

1995-01-01

48

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

2013-08-23

49

Axially-symmetrical oscillation of a semi-infinite layered medium with complex damping  

Microsoft Academic Search

A horizontally-layered, semi-infinite, isotropic medium with complex damping (O-damping) is considered to be excited by a prescribed periodic vertical motion at a point on the free surface. The resulting periodic displacement vector of the medium is expanded in a Neumann series of Bessel functions of the radial coordinate r. which ensures that the displacement vanishes as r->oo. Ordinary, linear, differential

Henry L. Langhaar; Arthur P. Boresi

1987-01-01

50

Infrared spectrum of a symmetrical phosphine-ozone complex in solid argon  

SciTech Connect

Cocondensation of Ar/PH/sub 2/ and Ar/O/sub 2/ samples at 12-18 K has produced sharp satellite absorptions at 1037.3 cm/sup -1/ below nu/sub 3/ of O/sub 3/ at 1039.9 cm/sup -1/, at 988.5 and 986.3 cm/sup -1/ below nu/sub 2/ of PH/sub 3/ at 994 cm/sup -1/, and at 705.2 cm/sup -1/ above nu/sub 2/ of O/sub 3/ at 704.4 cm/sup -1/. These bands, which photolyzed with red visible light and were reproduced on sample warming to allow reagent diffusion, are assigned to the PH/sub 3/-O/sub 3/ complex. A sharp sextet in /sup 16,18/O/sub 3/ experiments indicated a symmetrical attachment of ozone in the complex. The red visible photolysis is postulated to involve a charge-transfer mechanism. 32 references, 3 figures, 2 tables.

Withnall, R.; Hawkins, M.; Andrews, L.

1986-02-13

51

Modeling of Spherically Symmetric Droplet Flames Including Complex Chemistry: Effect of Water Addition on n-Heptane Droplet Combustion  

Microsoft Academic Search

A spherically symmetric quasi-steady model has been formulated for droplet combustion which includes complex chemistry and variable properties. The model is applied to mixtures of heptane and water.Calculations from the model show that the acetylene concentration inside a heptane flame increases with increasing droplet diameter. This trend suggests an increased propensity for soot formation with increasing droplet diameter which is

G. S. JACKSON; C. T. AVEDISIAN

1996-01-01

52

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

53

S. pombe linear elements: the modest cousins of synaptonemal complexes  

Microsoft Academic Search

Synaptonemal complexes (SCs) are not formed during meiotic prophase in the fission yeast, Schizosaccharomyces pombe. Instead, so-called linear elements (LinEs) are formed at the corresponding stages. LinEs are remarkable in that their number does not correspond to the number of chromosomes or bivalents and that the changes in their organisation during prophase do not evidently reflect the pairing of chromosomes.

Josef Loidl

2006-01-01

54

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

NASA Astrophysics Data System (ADS)

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

Baysal, Hüsnü

2012-12-01

55

A 2.5 mW 370 mV/pF high linearity stray-immune symmetrical readout circuit for capacitive sensors  

NASA Astrophysics Data System (ADS)

A stray-insensitive symmetrical capacitance-to-voltage converter for capacitive sensors is presented. By introducing a reference branch, a symmetrical readout circuit is realized. The linear input range is increased, and the systematic offsets of two input op-amps are cancelled. The common-mode noise and even-order distortion are also rejected. A chopper stabilization technique is adopted to further reduce the offset and flicker noise of the op-amps, and a Verilog-A-based varactor is used to model the real variable sensing capacitor. Simulation results show that the output voltage of this proposed readout circuit responds correctly, while the under-test capacitance changes with a frequency of 1 kHz. A metal-insulator-metal capacitor array is designed on chip for measurement, and the measurement results show that this circuit achieves sensitivity of 370 mV/pF, linearity error below 1% and power consumption as low as 2.5 mW. This symmetrical readout circuit can respond to an FPGA controlled sensing capacitor array changed every 1 ms.

Kaimin, Zhou; Ziqiang, Wang; Chun, Zhang; Zhihua, Wang

2012-06-01

56

Flexible, linear, tetranuclear palladium complexes supported by tetraphosphine ligands with electron-withdrawing groups.  

PubMed

A linearly ordered tetraphosphine containing electron-withdrawing substituent groups on the outer phosphorus atoms, meso-bis[{di(3,5-difluorophenyl)phosphinomethyl}phenylphosphino]methane (dpmppmF2), was prepared and reacted with [Pd2(RNC)6](PF6)2 and Pd(dba)2 to afford tetranuclear palladium complexes, [Pd4(?-dpmppmF2)2(RNC)3](PF6)2 (R = 2,6-xylyl (Xyl) (1), 2,4,6-mesityl (2), 2,6-diisopropylphenyl (3) and tert-butyl (4)), which involve an asymmetric {(RNC)Pd4(CNR)2}(2+) core supported by two dpmppmF2 ligands in anti-arrangement. Each terminal of the Pd4 chain was capped by terminal isocyanide and a semi-bridging RNC is introduced into one terminal Pd site. Mechanistic investigation suggested that the dipalladium(i) complex, [Pd2(?-dpmppmF2)2(RNC)2](PF6)2 (R = Xyl (6)), was a key intermediate to trap Pd(0) species by the uncoordinated outer phosphine pendants with electron-withdrawing groups. Variable-temperature UV-vis and (31)P{(1)H}, (1)H NMR spectroscopic studies demonstrated that the tetrapalladium complexes are quite fluxional in the solution state at high temperature (>20 °C) relating to a symmetric structure of [Pd4(?-dpmppmF2)2(RNC)2](PF6)2, and the asymmetric solid state structures are retained even in the solution at low temperature (<-60 °C). Theoretical calculations with DFT methods on the asymmetric (R = Xyl (1)) and symmetric (R = Xyl (1')) structures suggested that contribution of Pd(0)?Pd(I)-Pd(0)-Pd(I) with 60 cluster valence electrons (CVEs) would be dominant in 1, while the symmetric structure of 1' can be recognized as Pd(I)-Pd(0)-Pd(0)-Pd(I) with 58 CVEs. The new tetraphosphine dpmppmF2 was proven very effective in organizing dynamically flexible tetrapalladium chains. PMID:23880773

Tanase, Tomoaki; Hatada, Satoko; Mochizuki, Ayaka; Nakamae, Kanako; Kure, Bunsho; Nakajima, Takayuki

2013-07-24

57

Relaxation modulus—complex modulus interconversion for linear viscoelastic materials  

NASA Astrophysics Data System (ADS)

This paper is aimed at exploring the interconversion path between the relaxation modulus E(t) and the corresponding complex modulus E ?(?) for linear viscoelastic solid materials. In contrast to other approximate methods, the fast Fourier transform (FFT) algorithm is directly applied on the time-dependent part of the viscoelastic response R(t). Firstly, the method foundations are presented. Then, a theoretical example is performed by means of a generalized Maxwell model, where the influence of sampling conditions and eventual experimental error and data dispersion is analyzed. Finally, an application example using experimental data is carried out to assess the method. As a result, the proposed procedure allows obtaining the complex modulus by means of relaxation tests, and vice versa.

García-Barruetabeña, Jon; Cortés, Fernando; Abete, José Manuel; Fernández, Pelayo; Lamela, María Jesús; Fernández-Canteli, Alfonso

2012-10-01

58

Relaxation modulus—complex modulus interconversion for linear viscoelastic materials  

NASA Astrophysics Data System (ADS)

This paper is aimed at exploring the interconversion path between the relaxation modulus E( t) and the corresponding complex modulus E ?( ?) for linear viscoelastic solid materials. In contrast to other approximate methods, the fast Fourier transform (FFT) algorithm is directly applied on the time-dependent part of the viscoelastic response R( t). Firstly, the method foundations are presented. Then, a theoretical example is performed by means of a generalized Maxwell model, where the influence of sampling conditions and eventual experimental error and data dispersion is analyzed. Finally, an application example using experimental data is carried out to assess the method. As a result, the proposed procedure allows obtaining the complex modulus by means of relaxation tests, and vice versa.

García-Barruetabeña, Jon; Cortés, Fernando; Abete, José Manuel; Fernández, Pelayo; Lamela, María Jesús; Fernández-Canteli, Alfonso

2013-08-01

59

Equivalence of a complex PT-symmetric quartic Hamiltonian and a Hermitian quartic Hamiltonian with an anomaly  

Microsoft Academic Search

In a recent paper Jones and Mateo used operator techniques to show that the non-Hermitian PT-symmetric wrong-sign quartic Hamiltonian H=(1)\\/(2)p2-gx4 has the same spectrum as the conventional Hermitian Hamiltonian H˜=(1)\\/(2)p2+4gx4-2gx. Here, this equivalence is demonstrated very simply by means of differential-equation techniques and, more importantly, by means of functional-integration techniques. It is shown that the linear term in the Hermitian

Carl M. Bender; Dorje C. Brody; Jun-Hua Chen; Hugh F. Jones; Kimball A. Milton; Michael C. Ogilvie

2006-01-01

60

Geometrically non-linear analysis of symmetrically laminated composite and sandwich shells with a higher-order theory and C deg finite elements  

NASA Astrophysics Data System (ADS)

A C(sub 0) continuous displacement based finite element formulation of a higher-order theory for linear and geometrically non-linear analysis (which accounts for large displacements in the sense of von Karman) of symmetrically laminated composite and sandwich shells under transverse loads is presented. The displacement model accounts for non-linear and constant variation of tangential and transverse displacement components respectively, through the shell thickness. The assumed displacement model eliminates the use of shear correction coefficients. The discrete element chosen is nine-node quadrilateral element with nine degrees of freedom per node. The accuracy of the present formulation is then established by comparing the present results with the available analytical closed-form two-dimensional solutions, three-dimensional elasticity solutions and other finite element solutions. Some new results are generated for future comparisons to and evaluations of sandwich shells.

Kant, T.; Kommineni, J. R.

61

A C2-Symmetric, Basic Fe(III) Carboxylate Complex Derived from a Novel Triptycene-Based Chelating Carboxylate Ligand  

PubMed Central

A triptycene-based bis(benzoxazole) diacid ligand H2L2Ph4 bearing sterically encumbering groups was synthesized. Treatment of H2L2Ph4 with Fe(OTf)3 afforded a C2-symmetric trinuclear iron(III) complex, [NaFe3(L2Ph4)2(?3-O)(?-O2CCPh3)2(H2O)3](OTf)2 (8). The triiron core of this complex adopts the well known “basic iron acetate” structure where the heteroleptic carboxylates, comprising two dianionic ligands (L2Ph4)2? and two Ph3CCO2?, donate the six carboxylate bridges. The (L2Ph4)2? ligand undergoes only minor conformational changes upon formation of the complex.

Li, Yang; Wilson, Justin J.; Do, Loi H.; Apfel, Ulf-Peter; Lippard, Stephen J.

2012-01-01

62

Overlapping community detection in complex networks using symmetric binary matrix factorization.  

PubMed

Discovering overlapping community structures is a crucial step to understanding the structure and dynamics of many networks. In this paper we develop a symmetric binary matrix factorization model to identify overlapping communities. Our model allows us not only to assign community memberships explicitly to nodes, but also to distinguish outliers from overlapping nodes. In addition, we propose a modified partition density to evaluate the quality of community structures. We use this to determine the most appropriate number of communities. We evaluate our methods using both synthetic benchmarks and real-world networks, demonstrating the effectiveness of our approach. PMID:23848725

Zhang, Zhong-Yuan; Wang, Yong; Ahn, Yong-Yeol

2013-06-12

63

Overlapping community detection in complex networks using symmetric binary matrix factorization  

NASA Astrophysics Data System (ADS)

Discovering overlapping community structures is a crucial step to understanding the structure and dynamics of many networks. In this paper we develop a symmetric binary matrix factorization model to identify overlapping communities. Our model allows us not only to assign community memberships explicitly to nodes, but also to distinguish outliers from overlapping nodes. In addition, we propose a modified partition density to evaluate the quality of community structures. We use this to determine the most appropriate number of communities. We evaluate our methods using both synthetic benchmarks and real-world networks, demonstrating the effectiveness of our approach.

Zhang, Zhong-Yuan; Wang, Yong; Ahn, Yong-Yeol

2013-06-01

64

H NMR study of a complex between the lac repressor headpiece and a 22 base pair symmetric lac operator.  

PubMed

A complex between the lac repressor headpiece and a fully symmetric tight-binding 22 bp lac operator was studied by 2D NMR. Several 2D NOE spectra were recorded for the complex in both H2O and 2H2O. Many NOE cross-peaks between the headpiece and DNA could be identified, and changes in the chemical shift of the DNA protons upon complex formation were analyzed. Comparison of these data with those obtained for a complex between the headpiece and a 14 bp half-operator, studied previously [Boelens, R., Scheek, R. M., Lamerichs, R. M. J. N., de Vlieg, J., van Boom, J. H., & Kaptein, R. (1987) in DNA-ligand interactions (Guschlbauer, W., & Saenger, W., Eds.) pp 191-215, Plenum, New York], shows that two headpieces form a specific complex with the 22 bp lac operator in which each headpiece binds in the same way as found for the 14 bp complex. The orientation of the recognition helix in the major groove of DNA in these complexes is opposite with respect to the dyad axis to that found for other repressors. PMID:2742823

Lamerichs, R M; Boelens, R; van der Marel, G A; van Boom, J H; Kaptein, R; Buck, F; Fera, B; Rüterjans, H

1989-04-01

65

Error Correcting and Complexity Aspects of Linear Secret Sharing Schemes  

Microsoft Academic Search

\\u000a Linear secret sharing schemes and general access structures have played a key role in modern cryptography. Cramer-Damgård-Maurer\\u000a recently proved that any linear secret sharing scheme over a finite field can be a verifiable one. We give a simple proof based on error-correcting codes. Our proof allows us to generalize the Cramer-Damgård-Maurer’s\\u000a result to linear schemes over modules, which played an

Yvo Desmedt; Kaoru Kurosawa; Tri Van Le

2003-01-01

66

Accelerating the convergence of the Lanczos algorithm by the use of a complex symmetric Cholesky factorization: application to correlation functions in quantum molecular dynamics  

NASA Astrophysics Data System (ADS)

The theoretical description of reactive scattering, photo dissociation and a number of other problems in chemical physics can be formulated in terms of a correlation function between an initial and final state. It is shown by example that the convergence of correlation functions computed using a complex symmetric Lanczos algorithm can be significantly accelerated by using a complex symmetric version of the Cholesky decomposition. In fact, using the standard Lanczos approach without the Cholesky transformation, the correlation function might not converge at all. It is further demonstrated that a stopping criterion for the Lanczos recursions, based on an estimate for the upper bound of the error of the correlation function, can be extended to complex symmetric matrices and used as a reliable stopping criterion for the Cholesky-Lanczos approach.

Karlsson, Hans O.

2011-10-01

67

An analytical model to determine equilibrium quantities of azimuthally symmetric and mismatched charged particle beams under linear focusing  

SciTech Connect

The model developed here analytically allows to obtain equilibrium quantities of interest from high-intensity charged particle beams such as the emittance, beam envelope, and the number of beam halo particles. The results obtained in this work have been particularized to the case of initially homogeneous beams, with azimuthal symmetry, and focused by a constant magnetic field while confined in a linear channel. For validation, full self-consistent N-particle beam simulations have been carried out and its results compared with the predictions supplied by the developed hybrid numerical-analytical model. The agreement has been reasonable. Also, the model revealed to be useful to understand the basic physical aspects of the problem.

Nunes, R. P.; Pakter, R.; Rizzato, F. B. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, Caixa Postal 15051, CEP 91501-970, Porto Alegre, Rio Grande do Sul (Brazil)

2008-07-01

68

An algorithm for the k-error linear complexity of binary sequences with period 2n  

Microsoft Academic Search

Certain applications require pseudo-random sequences which are unpredictable in the sense that recovering more of the sequence from a short segment must be computationally infeasible. It is shown that linear complexity is useful in determining such sequences. A generalized linear complexity that has application to the security of stream ciphers is proposed, and an efficient algorithm is given for the

Mark Stamp; Clyde F. Martin

1993-01-01

69

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

2012-09-20

70

Tunable columnar mesophases utilizing C2 symmetric aromatic donor-acceptor complexes.  

PubMed

Derivatives of relatively electron rich 1,5-dialkoxynaphthalene (Dan) donors and relatively electron deficient 1,4,5,8-naphthalenetetracarboxylic diimide (Ndi) acceptors have been exploited in the folding and self-assembly of a variety of complex molecular systems in solution. Here, we report the use of Dan and Ndi derivatives to direct assembly of extended columns with alternating face-centered stacked structure in the solid state. A variety of 1:1 Dan:Ndi mixtures produced mesophases that were found to be stable over temperature ranges extending up to 110 degrees C. Analysis of these mesophases indicates mixtures with soft/plastic crystal phases and a few mixtures with the thermodynamic properties of true liquid crystals, all composed of alternating donor-acceptor columns within. Importantly, a correspondence was found between the clearing and crystallization points of the mesophase mixtures and the melting/clearing points of the component Ndi and Dan units, respectively. This correspondence enables the predictable tuning of mesophase phase transition temperatures. The study of sterically hindered derivatives led to a set of mixtures in which a dramatic and sudden color change (deep red to yellow) was observed upon crystallization of the mesophase due to a phase separation of the component donor and acceptor units. PMID:16771514

Reczek, Joseph J; Villazor, Karen R; Lynch, Vincent; Swager, Timothy M; Iverson, Brent L

2006-06-21

71

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

72

Use of nonlinear journal-bearing impedance descriptions to evaluate linear analysis of the steady-state imbalance response for a rigid symmetric rotor supported by two identical finite-length hydrodynamic journal bearings at high eccentricities  

Microsoft Academic Search

This paper concerns the investigation of validity limits of linear models in predicting rotor trajectory inside the bearing\\u000a clearance for a rigid symmetric rotor supported by two identical journal bearings operating at high eccentricities.\\u000a \\u000a \\u000a The inherent nonlinearity of hydrodynamic journal bearings becomes strong for eccentricities grater than 60% of the bearing\\u000a clearance where most existing linear models are not able

Jean-Claude Luneno; Jan-Olov Aidanpää

2010-01-01

73

Reducing the complexity of linear optics quantum circuits  

NASA Astrophysics Data System (ADS)

Integrated optical elements can simplify the linear optics used to simulate quantum circuits. These linear optical simulations of quantum circuits have been developed primarily in terms of the free space optics associated with single-photon interferometry. For an L-bit simulation the number of required free-space optical elements is ~2L if 50/50 beam splitters are used. The implementation (construction and alignment) of these circuits with these free-space elements is nontrivial. On the other hand, for the cases presented in this paper in which linear integrated optics (e.g., 2L×2L fiber couplers) are used, the number of optical devices does not grow exponentially with L. The problem is changed from having an exponential growth of the number of devices to having devices with an exponential growth in the number of ports. In addition to simplifying the construction, the association of an N×N fiber coupler with the discrete Fourier transform suggests alternative formulations for the circuits. Several examples of circuit reductions are given.

Howell, John C.; Yeazell, John A.

2000-05-01

74

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

PubMed

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

Vighneshvel, T; Arun, S P

2013-09-12

75

Stability and complexity of small random linear systems  

NASA Astrophysics Data System (ADS)

We explore the stability of the small random linear systems, typically involving 10-20 variables, motivated by dynamics of the world trade network and the US and Canadian power grid. This report was prepared as an account of work sponsored by an agency of the US Government. Neither the US Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the US Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the US Government or any agency thereof.

Hastings, Harold

2010-03-01

76

1. 2-GeV damping-ring complex for the Stanford Linear Collider  

SciTech Connect

The choice of parameters, the design, a 2-1/2 year consruction program and the early operation of a high field, high tune research and development damping ring complex for one of the two linear collider beams are described.

Fischer, G.E.; Davies-White, W.; Fieguth, T.; Wiedemann, H.

1983-07-01

77

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

78

Non-linear change in organizations: organization change management informed by complexity theory  

Microsoft Academic Search

Organizational change processes are often modeled on a linear understanding of change in which the process is composed of individual succeeding steps. In this paper, an organization change process in a Swedish telecommunication company, TelCo., is studied from the perspective of non-linearity. Complexity theory is used in the paper as a loosely coupled framework of theories and perspectives that do

Alexander Styhre

2002-01-01

79

Complex heat capacity measurements by TMDSC Part 1. Influence of non-linear thermal response  

Microsoft Academic Search

To treat data from temperature modulated differential scanning calorimetry (TMDSC) in terms of complex or reversing heat capacity one should know heat transfer and apparatus influences on experimental results. On the other hand one should pay attention that the response is linear because this is a prerequisite for data evaluation. The reason for non-linear thermal response is discussed and its

M. Merzlyakov; C. Schick

1999-01-01

80

Non-linear dynamic complexity of the human EEG during meditation  

Microsoft Academic Search

We used non-linear analysis to investigate the dynamical properties underlying the EEG in the model of Sahaja Yoga meditation. Non-linear dimensional complexity (DCx) estimates, indicating complexity of neuronal computations, were analyzed in 20 experienced meditators during rest and meditation using 62-channel EEG. When compared to rest, the meditation was accompanied by a focused decrease of DCx estimates over midline frontal

L. I. Aftanas; S. A. Golocheikine

2002-01-01

81

A design strategy of achievable linear optics for a complex storage ring lattice  

NASA Astrophysics Data System (ADS)

A design strategy is discussed in this paper, and it provides much convenience for effectively exploring achievable linear optics and globally investigating the flexibility of a complex lattice with super-periodicity. A matching method of fractional steps, which means separately finding the standard cell setting and the matching cell setting, is adopted to simplify the complexity of the linear beam optics design in the complex lattice. The multi-objective genetic algorithm is used to find most of all the stable linear optics, and reach a target solution after multi-generational propagation, both in the standard cell and the matching cell. A fitting algorithm with gradient information is used to restore the periodicity and symmetry of the lattice, and finely adjust the linear optics for further optimization. This design strategy is applied in the Shanghai Synchrotron Radiation Facility (SSRF) storage ring, and the results are presented.

Tian, Shun-Qiang

2010-07-01

82

Nonlinear and linear EEG complexity changes caused by gustatory stimuli in anorexia nervosa  

Microsoft Academic Search

The objective of the present study was to investigate the effects of pleasant and unpleasant gustatory stimuli on nonlinear and linear complexity measures of the EEG in healthy controls and in anorexia nervosa (AN) patients. The subjects were exposed to unpleasant (bitter tea) and pleasant (chocolate) gustatory stimuli for 2 min. Multichannel EEG was recorded and the dimensional complexity (point-correlation

Erika Tóth; István Kondákor; Ferenc Túry; Ágnes Gáti; Júlia Weisz; Márk Molnár

2004-01-01

83

On the complexity of minimum distance decoding of long linear codes  

Microsoft Academic Search

We suggest a decoding algorithm of -ary linear codes, which we call supercode decoding. It ensures the error probability that approaches the error probability of minimum- distance decoding as the length of the code grows. For the algorithm has the maximum-likelihood performance. The asymptotic complexity of supercode decoding is exponentially smaller than the complexity of all other methods known. The

Alexander Barg; Evgueni Krouk; Henk C. A. Van Tilborg

1999-01-01

84

Symmetric textures  

SciTech Connect

The Wolfenstein parametrization is extended to the quark masses in the deep ultraviolet, and an algorithm to derive symmetric textures which are compatible with existing data is developed. It is found that there are only five such textures.

Ramond, P. (Florida Univ., Gainesville, FL (United States). Dept. of Physics)

1993-01-01

85

Symmetric textures  

SciTech Connect

The Wolfenstein parametrization is extended to the quark masses in the deep ultraviolet, and an algorithm to derive symmetric textures which are compatible with existing data is developed. It is found that there are only five such textures.

Ramond, P. [Florida Univ., Gainesville, FL (United States). Dept. of Physics

1993-04-01

86

Monodentate non-C(2)-symmetric chiral N-heterocyclic carbene complexes for enantioselective synthesis. Cu-catalyzed conjugate additions of aryl- and alkenylsilylfluorides to cyclic enones.  

PubMed

A new class of enantioselective conjugate addition (ECA) reactions that involve aryl- or alkenylsilyl fluoride reagents and are catalyzed by chiral non-C(2)-symmetric Cu-based N-heterocyclic carbene (NHC) complexes are disclosed. Transformations have been designed based on the principle that a catalytically active chiral NHC-Cu-aryl or NHC-Cu-alkenyl complex can be accessed from reaction of a Cu-halide precursor with in situ-generated aryl- or alkenyltetrafluorosilicate. Reactions proceed in the presence of 1.5 equiv of the aryl- or alkenylsilane reagents and 1.5 equiv of tris(dimethylamino)sulfonium difluorotrimethylsilicate (TASF). Desired products are isolated in 63-97% yield and 73.5:26.5-98.5:1.5 enantiomeric ratio (47%-97% ee). A major focus of the present studies is the design, evaluation, and development of new chiral imidazolinium salts and their derived NHC-Cu complexes as catalysts that promote reactions of various carbosilanes to a range of electrophilic substrates. Toward this end, nearly 20 new chiral monodentate imidazolinium salts, most of which are non-C(2)-symmetric, have been prepared and fully characterized and their ability to serve as catalysts in the ECA reactions has been investigated. PMID:19445467

Lee, Kang-sang; Hoveyda, Amir H

2009-06-19

87

The Pipeback Switch: High Performance Packet Switching with Guaranteed Delivery and Linear Buffer Complexity  

Microsoft Academic Search

A high performance packet switching archi- tecture called the Pipeback switch is proposed. This archi- tecture ensures lossless packet delivery while maintaining linear buffer complexity. The Pipeback switch improves upon the popular Knockout switch proposed by Y. Yeh et al. Both switches use an N × N space division fabric with output queuing and both designs are motivated by the

Saqib Raza; Zartash Afzal Uzmi

88

Fast rational interpolation, Reed-Solomon decoding, and the linear complexity profiles of sequences  

Microsoft Academic Search

An asymptotically fast algorithm for solving the generalized rational interpolation problem is presented. This problem has been studied as part of system theory and is related to the solution of the classical and Welch-Berlekamp (1983) key equations which arise in Reed-Solomon decoding. The algorithm can also be used to compute the linear complexity profile of a binary sequence of length

Simon R. Blackburn

1997-01-01

89

Equivalence of a complex PT-symmetric quartic Hamiltonian and a Hermitian quartic Hamiltonian with an anomaly  

Microsoft Academic Search

In a recent paper Jones and Mateo used operator techniques to show that the\\u000anon-Hermitian $\\\\cP\\\\cT$-symmetric wrong-sign quartic Hamiltonian $H=\\\\half\\u000ap^2-gx^4$ has the same spectrum as the conventional Hermitian Hamiltonian\\u000a$\\\\tilde H=\\\\half p^2+4g x^4-\\\\sqrt{2g} x$. Here, this equivalence is demonstrated\\u000avery simply by means of differential-equation techniques and, more importantly,\\u000aby means of functional-integration techniques. It is shown that the

Carl M. Bender; Dorje C. Brody; Jun-Hua Chen; Hugh F. Jones; Kimball A. Milton; Michael C. Ogilvie

2006-01-01

90

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

91

Observation of a Linear Isomer of the C{_3}-Xe Van Der Waals Complex  

NASA Astrophysics Data System (ADS)

Our emission spectra of the C{_3}-Xe vdW (van der Waals) complex obtained near the 2^{2-}_0 band of the Ã-X˜ system of C{_3} showed that a stable linear isomer is present at high C{_3}-bending vibrational levels ({v_b} ? 4) of the ground electronic state. Ab initio calculations at the level of CCSD(T)/cc-pVTZ (effective core potential of the Xe atom) support our spectral assignments. The linear isomer lies about 250 cm ^{-1} above the T-shaped isomer. From the calculated potential, large amplitude vdW bending motion is expected in the high v_b levels; this explains the congested emission spectra observed from vdW bands near the 2^{4-}_0 band of C{_3} . Molecular orbitals at the level of HF-SCF showed that bonding with the 5p orbital of the Xe atom in a linear configuration (along the a-axis of C{_3}) is stabilized by mixing some high-lying ?^* bonding character into one of the C-C bonds. This type of bonding is not possible in the Ar and Kr complexes because in these two complexes 3p or 4p orbitals of the rare gas atoms are used. The isomerization from the T-shaped isomer to the linear isomer probably occurs rapidly in the à state.

Tham, Keng Seng; Chao, Jun-Mei; Zhang, Guiqiu; Merer, Anthony J.; Hsu, Yen-Chu; Hu, Wei-Ping

2009-06-01

92

Observation of Defect States in PT-Symmetric Optical Lattices  

NASA Astrophysics Data System (ADS)

We provide the first experimental demonstration of defect states in parity-time (PT) symmetric mesh-periodic potentials. Our results indicate that these localized modes can undergo an abrupt phase transition in spite of the fact that they remain localized in a PT-symmetric periodic environment. Even more intriguing is the possibility of observing a linearly growing radiation emission from such defects provided their eigenvalue is associated with an exceptional point that resides within the continuum part of the spectrum. Localized complex modes existing outside the band-gap regions are also reported along with their evolution dynamics.

Regensburger, Alois; Miri, Mohammad-Ali; Bersch, Christoph; Näger, Jakob; Onishchukov, Georgy; Christodoulides, Demetrios N.; Peschel, Ulf

2013-05-01

93

A self-consistent three-wave coupling model with complex linear frequencies  

SciTech Connect

A three-wave coupling model with complex linear frequencies is investigated for the nonlinear interaction in a triad that has linearly unstable and stable modes. Time scales associated with linear and nonlinear physics are identified and compared with features of the frequency spectrum. From appropriate time scales, the frequency spectra are well characterized even in the transition to the steady state. The nonlinear time scales that best match spectral features are the nonlinear frequency of the fixed point and a frequency that depends on the amplitude displacement from the fixed point through the large-amplitude Jacobian elliptic solution. Two limited efforts to model the effect of other triads suggest robustness in the single triad results.

Kim, J.-H.; Terry, P. W. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2011-09-15

94

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

95

Naphthalene Complexation by ?-Cyclodextrin: Influence of Added Short Chain Branched and Linear Alcohols  

Microsoft Academic Search

Naphthalene forms 1 : 1 complexes with ß-cyclodextrin (ß-CD)in water. The binding constant is 377 ± 35 M-1. Addition of linear or branched alcohols causes a reduction in the apparent strength of naphthalene binding (Kapp) compared to the value in the absence of additives. For example, 1% 1-pentanol reduces Kapp to 184 ± 31 M-1. Branching does not alter Kapp

Christopher H. Evans; Morgan Partyka; Jan Van Stam

2000-01-01

96

On the Computational Complexity of Decidable Fragments of First-Order Linear Temporal Logics  

Microsoft Academic Search

We study the complexity of some fragments of first-order temporal logic over natural numbers time. The one-variable fragment of linear first-order temporal logic even with sole temporal operator □ is EXPSPACE-complete (this solves an open problem of J. Halpern and M. Vardi (1989)). So are the one-variable, two-variable and monadic monodic fragments with Until and Since. If we add the

Ian M. Hodkinson; Roman Kontchakov; Agi Kurucz; Frank Wolter; Michael Zakharyaschev

2003-01-01

97

Novel 3DP Drug Delivery Devices with Complex Structures for Linear Drug Release Profiles  

Microsoft Academic Search

A novel drug delivery device (DDD) with complex structures for providing linear drug release profiles was designed and fabricated directly from the CAD models using three-dimensional printing technique (3DP) systems. The DDDs were in donut shape and had local concentration variations of the release-retarding polymer in their three regions. Environmental scanning electron microscopy clearly showed that the two dense regions,

Deng-Guang Yu; Li-Min Zhu; C. Branford-White; E. D. Welbeck; Xiao-Yan Li; Xiang-Liang Yang

2009-01-01

98

New titanium complexes with symmetric or asymmetric cis-9,10-dihydrophenanthrenediamide ligands formed through sequential intramolecular C-C bond-forming reactions.  

PubMed

A series of new titanium(IV) complexes with symmetric or asymmetric cis-9,10-dihydrophenanthrenediamide ligands, cis-9,10-PhenH(2)(NR)(2)Ti(O(i)Pr)(2) [PhenH(2) = 9,10-dihydrophenanthrene, R = 2,6-(i)Pr(2)C(6)H(3) (2a), 2,6-Et(2)C(6)H(3) (2b), 2,6-Me(2)C(6)H(3) (2c)], cis-9,10-PhenH(2)(NR(1))(NR(2))Ti(O(i)Pr)(2) [R(1) = 2,6-(i)Pr(2)C(6)H(3), R(2) = 2,6-Et(2)C(6)H(3) (2d); R(1) = 2,6-(i)Pr(2)C(6)H(3), R(2) = 2,6-Me(2)C(6)H(3) (2e)], and [cis-9,10-PhenH(2)(NR(1))(2)][o-C(6)H(4)(CH=NR(2))]TiO(i)Pr [R(1) = 2,6-(i)Pr(2)C(6)H(3), R(2) = 2,6-Et(2)C(6)H(3) (3a); R(1) = 2,6-(i)Pr(2)C(6)H(3), 2,6-Me(2)C(6)H(3) (3b)], have been synthesized from the reactions of TiCl(2)(O(i)Pr)(2) with o-C(6)H(4)(CH=NR)Li [R = 2,6-(i)Pr(2)C(6)H(3), 2,6-Et(2)C(6)H(3), 2,6-Me(2)C(6)H(3)]. The symmetric complexes 2a-2c were obtained from the reactions of TiCl(2)(O(i)Pr)(2) with 2 equiv of the corresponding o-C(6)H(4)(CH=NR)Li followed by intramolecular C-C bond-forming reductive elimination and oxidative coupling processes, while the asymmetric complexes 2d-2e were formed from the reaction of TiCl(2)(O(i)Pr)(2) with two different types of o-C(6)H(4)(CH=NR)Li sequentially. The complexes 3a and 3b were also isolated from the reactions for complexes 2d and 2e. All complexes were characterized by (1)H and (13)C NMR spectroscopy, and the molecular structures of 2a, 2b, 2e, and 3a were determined by X-ray crystallography. PMID:21114325

Zhao, Dapeng; Gao, Bo; Gao, Wei; Luo, Xuyang; Tang, Duihai; Mu, Ying; Ye, Ling

2010-11-29

99

The uranium-Xylidyl Blue I complex and its application in linear sweep polarography.  

PubMed

The linear sweep polarographic wave of the uranium-Xylidyl Blue I complex in ethylenediamine-1,10-phenanthroline-hydrochloric acid medium has been studied. The complex, corresponding to UO(2)(XBI)(2-)(2) with log beta' = 9.09 (by polarography), 8.81 (by spectrophotometry), is strongly adsorbed on the surface of the mercury electrode. The polarographic wave is attributed to the reduction of Xylidyl Blue I in the complex. The method is very sensitive with a detection limit of 3 x 10(-8)M. The wave height is proportional to the concentration of uranium over the range 8 x 10(-8)-7 x 10(-6)M. Solvent extraction is used to separate possible interferences. The recommended procedure has been applied to the determination of trace amounts of uranium in ores. PMID:18964412

Zhao, Z; Cai, X; Li, P

1987-09-01

100

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

PubMed

SHARPIN is a ubiquitin-binding and ubiquitin-like-domain-containing protein which, when mutated in mice, results in immune system disorders and multi-organ inflammation. 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 dysregulation of NF-?B and apoptotic signalling pathways, explaining the severe phenotypes displayed by chronic proliferative dermatitis (cpdm) in SHARPIN-deficient mice. Upon binding to the LUBAC subunit HOIP (also known as RNF31), SHARPIN stimulates the formation of linear ubiquitin chains in vitro and in vivo. Coexpression of SHARPIN and HOIP promotes linear ubiquitination of NEMO (also known as IKBKG), an adaptor of the I?B kinases (IKKs) and subsequent activation of NF-?B signalling, whereas 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 (also known as RBCK1), another HOIP-binding component of LUBAC. In addition, SHARPIN deficiency leads to rapid cell death upon tumour-necrosis factor ? (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

2011-03-31

101

Description and characterization of the complex modes in a linear chain of gold nanospheres  

NASA Astrophysics Data System (ADS)

In this paper, complex modes in a linear chain of gold nanospheres are analyzed, accounting for metal losses. Dispersion diagrams are computed for travelling modes with both longitudinal and transverse (with respect to the array axis) polarization states. The procedure outlined in this work allows for the description of single mode evolution varying frequency, thus the modal dispersion diagrams are composed by the superposition of all the different modes in the one dimensional array. Each nanoparticle is modeled as an electric dipole, by adopting the single dipole approximation, and the complex zeroes of the homogeneous equation characterizing the field in the periodic structure are computed. The Ewald method is employed to analytically continue the periodic Green's function into the complex spectral domain and to achieve rapid convergence. Full characterization of the modes is provided in terms of their direction of propagation (forward/backward), their guidance and radiation properties (bound/leaky), the position of their wavenumber on the Riemann sheet (proper/improper), and also in terms of their possible physical excitation in the structure by a source in proximity of the array or a defect (physical/nonphysical modes). Understanding the modes excitable in this kind of structures is essential for possible applications in which the linear chain can be employed, from near-field enhancement to SERS, and innovative sensors.

Campione, Salvatore; Steshenko, Sergiy; Capolino, Filippo

2011-02-01

102

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

103

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

104

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

2011-08-26

105

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

106

Organogold(I) complexes of a C 2-symmetric diacetylide ligand derived from 1,1?-bi-2-naphthol  

Microsoft Academic Search

Alkynylgold(I) complexes incorporating a chiral binaphthyl group have been prepared. Bis(alkyne) reagents [rac-1,1?-C20H12-2,2?-(OCH2CCH)2] (1) and [rac-1,1?-C20H12-2,2?-(OC(O)CH2CCH)2] (2), react with [AuCl(SMe2)] and base to give insoluble oligomeric alkynylgold(I) complexes [rac-1,1?-C20H12-2,2?-(OCH2CCAu)2]n (3) and [rac-1,1?-C20H12-2,2?-(OC(O)CH2CCAu)2]n (4), which react with phosphine or diphosphine ligands to give soluble complexes [rac-1,1?-C20H12-2,2?-(OCH2CCAuPR3)2] (5), R=Ph or Cy, [rac-1,1?-C20H12-2,2?-(OCH2CCAu)2(Ph2P(CH2)nPPh2)] (6), or [rac-1,1?-C20H12-2,2?-(OC(O)CH2CCAu)2(Ph2P(CH2)nPPh2)] (7), with n=3–5. Several of the complexes

Tara J. Burchell; Michael C. Jennings; Richard J. Puddephatt

2006-01-01

107

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

108

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

109

Dissipative particle dynamics simulations of complexes comprised of cylindrical polyelectrolyte brushes and oppositely charged linear polyelectrolytes.  

PubMed

Dissipative particle dynamics (DPD) approach is used to investigate the conformational behaviors and interactions of the complex between a cylindrical polyelectrolyte brush (CPB) and linear polyelectrolytes (LPs) with opposite charges. The effective complex between CPB and LPs and its dependence on the amount and length of LPs are examined. It is found that the CPB conformation presents collapse and reswelling with the increasing amount of LPs. The collapse is caused by the replacement of monovalent CPB counterions by LPs and the condensation of LPs on the CPB which reduce the osmotic pressure inside the brush. The swelling of the collapsed CPB is induced by the excluded volume effects of additionally absorbed LPs and LP counterions. The results show that the addition of LPs can not enhance the effective complex between the CPB and LPs when the total charge of LPs exceeds that of CPB. Our simulation also demonstrates that the increase of the LP length leads to a shrinking of the CPB which consequently exhibits rod-like or spherical conformations. The most effective complex between a CPB and LPs can be reached only when the contour length of LPs is not less than that of the CPB side chain. PMID:19708154

Yan, Li-Tang; Zhang, Xinjun

2009-04-01

110

Less symmetrical dicopper(II) complexes as catechol oxidase models--an adjacent thioether group increases catecholase activity.  

PubMed

Three new unsymmetrical compartmental dinucleating ligands, 4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-[{2-(1-piperidyl)ethyl}aminomethyl]phenol (HL1), 4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-[{2-(morpholin-4-yl)ethyl}aminomethyl]phenol (HL2), and 4-bromo-2-(4-methylpiperazin-1-ylmethyl)-6-[{2-(thiomorpholin-4-yl)ethyl}aminomethyl]phenol (HL3), have been synthesized in order to model the active site of type 3 copper proteins. The dicopper(II) complexes of these ligands give first hints about the influence of a thioether group close to the metal site. The bromophenol-based ligands have one piperazine arm and one other bidentate arm in positions 2 and 6 of the phenolic ring, respectively. With each ligand a dinuclear copper(II) complex was prepared and structurally characterized. The copper ions were found to have square pyramidal environments and a mixture of endogenous phenoxo and exogenous acetate bridging. The influence of a heteroatom in one arm of the ligand on catecholase activity and speciation in solution was studied by UV/Vis spectroscopy, ESI-MS experiments and, DFT calculations. PMID:15619727

Merkel, Michael; Möller, Niclas; Piacenza, Manuel; Grimme, Stefan; Rompel, Annette; Krebs, Bernt

2005-02-01

111

Spin depolarizing effect in collisions with neutral hydrogen. II. Application to simple/complex ions in spherically symmetric states  

NASA Astrophysics Data System (ADS)

Aims: We develop an accurate and general semi-classical formalism that deals with the definition and the calculation of the collisional depolarizing constants of the levels of simple and complex singly-ionized atoms in arbitrary s-states perturbed by collisions with hydrogen atoms. The case of ions with hyperfine structure is investigated fully. Methods: We obtain potential energy curves based on the MSMA exchange perturbation theory by employing the Unsöld approximation. These potentials enter the Schrödinger equation to determine the collisional T-matrix elements in a semi-classical description. We use the T-matrix elements for the calculation of the collisional depolarization rates of simple atoms. Then, we use these rates to calculate the collisional coefficients in cases of ions with hyperfine structure. Results: We evaluate the collisional depolarization and polarization transfer rates of the ground levels of the ionized alkaline earth metals Be II, Mg II, Ca II, Sr II, and Ba II. We study the variation of the collisional rates with effective principal quantum number n* characterizing an arbitrary s-state of a perturbed simple ion. We find that the collisional rates for simple ions obey simple power laws as a function of n^*. We present direct and indirect formulations of the problem of the calculation of the depolarization and polarization transfer rates of levels of complex atoms and hyperfine levels from those for simple atoms. In particular, the indirect method allows a quick and simple calculation with its simple power-law relations. For the state 4s ^2S{1/2} of Ca II, our computed rate of the destruction of orientation differs from existing quantum chemistry calculations by only 4% at T=5000 K.

Derouich, M.; Barklem, P. S.

2007-02-01

112

Linear and nonlinear optics of light harvesting complexes: TCL- and Bloch Equations for linear spectra and saturation dynamics  

Microsoft Academic Search

Bloch equations for the optical and electronic processes in light-harvesting-complexes, important nanostructures in photo-processes, are presented. The theory includes Förster excitation transfer, electron-phonon coupling and arbitrary strong light fields leading to saturation phenomena.

Marten Richter; Thomas Renger; Andreas Knorr

2007-01-01

113

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

PubMed

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

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

2006-03-20

114

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.L.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 RN-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 RNN 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

115

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

116

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.  

PubMed

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. PMID:23099161

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

2012-09-28

117

Multifrontal Parallel Distributed Symmetric and Unsymmetric Solvers.  

National Technical Information Service (NTIS)

The authors consider the solution of both symmetric of sparse linear equations. A new parallel distributed memory multifrontal approach is described. To handle numerical pivoting efficiently, a parallel asynchronous algorithm with dynamic scheduling of th...

P. R. Amestoy I. S. Duff J. Y. L'Excellent

1998-01-01

118

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

PubMed

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

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

2006-05-17

119

A Reduced Complexity Linear QC-LDPC Encoding with Parity Vector Correction Technique  

NASA Astrophysics Data System (ADS)

A new approach for encoding one class of quasi-cyclic low-density parity-check (QC-LDPC) codes is proposed. The proposed encoding method is applicable to parity-check matrices having dual-diagonal parity structure with single column of weight three in the parity generation region. Instead of finding the parity bits directly, the proposed method finds parity bits through vector correction. While the proposed LDPC encoding scheme is readily applicable to matrices defined in the IEEE physical layer standards, the computational complexity of the post processing operation for extraction of correction vector requires less effort than solving the linear equations involved with finding the parity bit as proposed by Myung et al.

Yoon, Chanho; Lee, Hoojin; Kang, Joonhyuk

120

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

121

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

SciTech Connect

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

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

2010-11-15

122

High-resolution ocean dynamics from microcanonical formulations in non linear complex signal analysis  

NASA Astrophysics Data System (ADS)

This article develops on a microcanonical formulation [1,2] for the analysis of the dynamics in acquisitions of remotely sensed oceanographic images using non-linear methods. In new approaches to complexity [3,4], fundamental quantities such as singularity exponents (SEs) are computed without any stationary hypothesis, i.e. in situations far from statistical equilibrium, as it is the case in Oceanography. SEs characterize rigorously complex oceanographic coherent structures and their relations. These quantities can be computed from the acquired data using advanced signal processing tools [5]. Computational precision is pivotal and we first give some details on techniques available in non-linear signal processing for computing SEs. SEs relate to the geometric structures linked with the cascading properties of indefinitely divisible variables in turbulent flows. In a second step, we show how cascading properties can be represented by optimal wavelets (OWs) [6]; this opens new and fascinating directions of research for the determination of ocean motion field at high spatial resolution. OWs in a microcanonical sense pave the way for the determination of the energy injection mechanisms between the scales. We describe a new method for the complete evaluation of oceanic motion field which consists in propagating along the scales the norm and the orientation of ocean dynamics deduced at low spatial resolution (geostrophic from altimetry [7] and a part of ageostrophic from wind stress products). Using this approach, there is no need to use several temporal occurences as in Optical Flow, Maximum Cross Correlation or FSLE techniques. Instead, the proper determination of the turbulent cascading and energy injection mechanisms in oceanographic signals allows the determination of oceanic motion field at the SST or Ocean colour spatial resolution (pixel size: 4 kms) which often surpasses the results obtained with SQG models. We use the Regional Ocean Modelling System (ROMS) [8] to validate the results on simulated data and compare the motion fields obtained with other techniques.

Yahia, H.; Sudre, J.; Garçon, V.; Pottier, C.

2012-04-01

123

DNA complex lesions induced by protons and ? -particles: track structure characteristics determining linear energy transfer and particle type dependence  

Microsoft Academic Search

The yield of DNA double-strand breaks (dsb) and DNA complex lesions induced by protons and ?-particles of various energies was simulated using a Monte Carlo track structure code (MOCA15) and a simple model of the DNA\\u000a molecule. DNA breaks of different complexity were analysed. The linear energy transfer (LET) and particle-type dependence\\u000a of lesions of higher complexity seems to confirm

A. Ottolenghi; M. Merzagora; H. G. Paretzke

1997-01-01

124

Hybrid organic/inorganic complexes based on electroactive tetrathiafulvalene-functionalized diphosphanes tethered to C(3)-symmetrized Mo(3)Q(4) (Q = S, Se) clusters.  

PubMed

A two-step procedure for the preparation of hybrid complexes based on electroactive tetrathiafulvalene (TTF)- functionalized o-P(2) diphosphanes (o-P(2) = 3,4-dimethyl-3,4-bis(diphenylphosphino)tetrathiafulvalene) and inorganic C(3)-symmetrized Mo(3)Q(4) (Q = S, Se) clusters, namely, [Mo(3)S(4)Cl(3)(o-P(2))(3)]PF(6) ([1]PF(6)) and [Mo(3)Se(4)Cl(3)(o-P(2))(3)]PF(6) ([2]PF(6)), is reported. Their molecular and electronic structures are also described on the basis of X-ray diffraction experiments and density functional theory (DFT) calculations aimed at understanding the interactions established between both the organic and the inorganic parts. Cyclic voltammograms of compounds [1]PF(6) and [2]PF(6) display reduction features associated to the Mo(3)Q(4) core and oxidation characteristics due to the TTF skeleton. The oxidation chemistry of [1]PF(6) and [2]PF(6) in solution is also investigated by means of in situ electrospray ionization (ESI) mass spectrometry, UV-vis, and, electron paramagnetic resonance (EPR) measurements. Upon addition of increasing amounts of NOPF(6) (less than 3 equiv), the sequential formation of 1(n+) (n = 1-4) species was observed whereas addition of a 3-fold excess of NOPF(6) allows to access the three-electron oxidized [Mo(3)S(4)Cl(3)(o-P(2))(3)](4+) (1(4+)) and [Mo(3)Se(4)Cl(3)(o-P(2))(3)](4+) (2(4+)) cations. These 1(4+) and 2(4+) cations represent still rare examples of complexes with oxidized TTF-ligands that are remarkably stable either toward diphosphane dissociation or phosphane oxidation. Polycrystalline samples of compound [1](PF(6))(4) were obtained by oxidation of compound [1]PF(6) using NOPF(6) which were analyzed by solid state absorption, UV-vis, and Raman spectroscopies. PMID:20085305

Avarvari, Narcis; Kiracki, Kaplan; Llusar, Rosa; Polo, Victor; Sorribes, Ivan; Vicent, Cristian

2010-02-15

125

Probabilistic cloning of three symmetric states  

SciTech Connect

We study the probabilistic cloning of three symmetric states. These states are defined by a single complex quantity, the inner product among them. We show that three different probabilistic cloning machines are necessary to optimally clone all possible families of three symmetric states. We also show that the optimal cloning probability of generating M copies out of one original can be cast as the quotient between the success probability of unambiguously discriminating one and M copies of symmetric states.

Jimenez, O. [Center for Optics and Photonics, Departamento de Fisica, Universidad de Concepcion, Casilla 4016, Concepcion (Chile); Departamento de Fisica, Facultad de Ciencias Basicas, Universidad de Antofagasta, Casilla 170, Antofagasta (Chile); Bergou, J. [Department of Physics, Hunter College, City University of New York, 695 Park Avenue, New York, New York 10021 (United States); Delgado, A. [Center for Optics and Photonics, Departamento de Fisica, Universidad de Concepcion, Casilla 4016, Concepcion (Chile); Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile)

2010-12-15

126

Linear dichroism studies of binding site structures in solution. Complexes between DNA and basic arylmethane dyes.  

PubMed

The interaction between B-form DNA and twelve cationic triaryl-methane dyes was studied with respect to optical properties and stabilities, using linear dichroism (LD) and aqueous two-phase partition techniques. Monovalent dyes derived from crystal violet as a rule form a single strong complex (K1 ca 10(5) M-1; site density per nucleotide base n1 ca 0.1 at 0.1M ionic strength) in which the plane of the dye is at an angle of less than 50 degrees to the local DNA helix axis. The complex with fuchsin is weaker (10(4) M-1) but can be explained by a similar orientation. For some of the dyes (those with pseudo-C2v symmetry) the angular orientations of two molecule-fixed axes can be obtained. For the divalent methyl green a second complex appears to be formed at low ionic strength. Methyl green (and to some extent 2-thiophene green and malachite green) show exciton splitting in the LD spectrum and circular dichroism assignable to exciton coupling between transition dipoles roughly parallel to the helical strands, indicating a dye-dye interaction. The optical data, supported by fitting experiments with space-filling models, suggests a general structure for the binding site. The dye is not intercalated but is bound to exposed hydrophobic regions in the major groove. The ligand is in part (the charged amino groups) in contact with the phosphoribose chain but its main surface lies against the hydrophobic base-pair stack. For a diphenylmethane dye, Michler's hydro blue, a perpendicular orientation was observed, possibly due to intercalation. PMID:647099

Nordén, B; Tjerneld, F; Palm, E

1978-03-01

127

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 (?=632.8 nm) by employing the Z-scan technique. The magnitude of nonlinear refractive index and nonlinear absorption coefficient were found to be -2.11×10-8 cm2/W and -1.201×10-3 cm/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 10-6 esu. 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

128

Adjusting for confounding by neighborhood using generalized linear mixed models and complex survey data.  

PubMed

When investigating health disparities, it can be of interest to explore whether adjustment for socioeconomic factors at the neighborhood level can account for, or even reverse, an unadjusted difference. Recently, we proposed new methods to adjust the effect of an individual-level covariate for confounding by unmeasured neighborhood-level covariates using complex survey data and a generalization of conditional likelihood methods. Generalized linear mixed models (GLMMs) are a popular alternative to conditional likelihood methods in many circumstances. Therefore, in the present article, we propose and investigate a new adaptation of GLMMs for complex survey data that achieves the same goal of adjusting for confounding by unmeasured neighborhood-level covariates. With the new GLMM approach, one must correctly model the expectation of the unmeasured neighborhood-level effect as a function of the individual-level covariates. We demonstrate using simulations that even if that model is correct, census data on the individual-level covariates are sometimes required for consistent estimation of the effect of the individual-level covariate. We apply the new methods to investigate disparities in recency of dental cleaning, treated as an ordinal outcome, using data from the 2008 Florida Behavioral Risk Factor Surveillance System (BRFSS) survey. We operationalize neighborhood as zip code and merge the BRFSS data with census data on ZIP Code Tabulated Areas to incorporate census data on the individual-level covariates. We compare the new results to our previous analysis, which used conditional likelihood methods. We find that the results are qualitatively similar. PMID:22975990

Brumback, Babette A; Zheng, Hao W; Dailey, Amy B

2012-09-13

129

Design and synthesis of novel hybrid metal complex-DNA conjugates: key building blocks for multimetallic linear DNA nanoarrays.  

PubMed

We describe here a short and efficient synthetic route for incorporating terpyridine based metal complexes at the 3'-extremity of both single and bis-oligonucleotide (bis-ODN) stretches to form novel metal complex-ODN conjugates. All single stranded mono and bis-ODN tethered metal complexes and the respective duplex ODNs were characterized by circular dichroism spectroscopy and UV-Vis melting experiments. Duplexes formed by these hybrid metal complex-DNA conjugates showed around 4-5 degrees C stabilization with respect to the unmodified duplexes. Moreover hybridization of two complementary bis-ODN tethered metal complexes at different ratios in solution gave rise to a self-assembled nanometric linear network, which was characterized by non-denaturing gel electrophoresis and TEM studies. Thus, our simple synthetic strategy would contribute to develop multimetallic 2D-DNA nanoarrays where we can place different metal complexes at regular intervals along the ODN stretches. PMID:19532989

Ghosh, Sumana; Pignot-Paintrand, Isabelle; Dumy, Pascal; Defrancq, Eric

2009-05-18

130

EVALUATING PREDICTIVE ERRORS OF A COMPLEX ENVIRONMENTAL MODEL USING A GENERAL LINEAR MODEL AND LEAST SQUARE MEANS  

EPA Science Inventory

A General Linear Model (GLM) was used to evaluate the deviation of predicted values from expected values for a complex environmental model. For this demonstration, we used the default level interface of the Regional Mercury Cycling Model (R-MCM) to simulate epilimnetic total mer...

131

Prediction of complex human traits using the genomic best linear unbiased predictor.  

PubMed

Despite important advances from Genome Wide Association Studies (GWAS), for most complex human traits and diseases, a sizable proportion of genetic variance remains unexplained and prediction accuracy (PA) is usually low. Evidence suggests that PA can be improved using Whole-Genome Regression (WGR) models where phenotypes are regressed on hundreds of thousands of variants simultaneously. The Genomic Best Linear Unbiased Prediction (G-BLUP, a ridge-regression type method) is a commonly used WGR method and has shown good predictive performance when applied to plant and animal breeding populations. However, breeding and human populations differ greatly in a number of factors that can affect the predictive performance of G-BLUP. Using theory, simulations, and real data analysis, we study the performance of G-BLUP when applied to data from related and unrelated human subjects. Under perfect linkage disequilibrium (LD) between markers and QTL, the prediction R-squared (R(2)) of G-BLUP reaches trait-heritability, asymptotically. However, under imperfect LD between markers and QTL, prediction R(2) based on G-BLUP has a much lower upper bound. We show that the minimum decrease in prediction accuracy caused by imperfect LD between markers and QTL is given by (1-b)(2), where b is the regression of marker-derived genomic relationships on those realized at causal loci. For pairs of related individuals, due to within-family disequilibrium, the patterns of realized genomic similarity are similar across the genome; therefore b is close to one inducing small decrease in R(2). However, with distantly related individuals b reaches very low values imposing a very low upper bound on prediction R(2). Our simulations suggest that for the analysis of data from unrelated individuals, the asymptotic upper bound on R(2) may be of the order of 20% of the trait heritability. We show how PA can be enhanced with use of variable selection or differential shrinkage of estimates of marker effects. PMID:23874214

de Los Campos, Gustavo; Vazquez, Ana I; Fernando, Rohan; Klimentidis, Yann C; Sorensen, Daniel

2013-07-11

132

Upscaling Radionuclide Retardation?Linking the Surface Complexation and Ion Exchange Mechanistic Approach to a Linear Kd Approach  

SciTech Connect

The LLNL near-field hydrologic source term (HST) model is based on a mechanistic approach to radionuclide retardation-that is, a thermodynamic description of chemical processes governing retardation in the near field, such as aqueous speciation, surface complexation, ion exchange, and precipitation The mechanistic approach allows for radionuclide retardation to vary both in space and time as a function of the complex reaction chemistry of the medium. This level of complexity is necessary for near-field HST transport modeling because of the non-linear reaction chemistry expected close to the radiologic source. Large-scale Corrective Action Unit (CAU) models-into which the near-field HST model results feed-require that the complexity of the mechanistic approach be reduced to a more manageable form (e.g. Linear, Langmuir, or Freundlich sorption isotherms, etc). The linear sorption isotherm (or K{sub d}) approach is likely the most simple approach for large-scale CAU models. It may also be the most appropriate since the reaction chemistry away from the near field is expected to be less complex and relatively steady state. However, if the radionuclide retardation approaches in near-field HST and large-scale CAU models are different, they must be proved consistent. In this report, we develop a method to link the near-field HST and large-scale CAU model radionuclide retardation approaches.

Zavarin, M; Carle, S; Maxwell, R

2004-05-14

133

Multipeaked gap solitons in PT-symmetric optical lattices.  

PubMed

We report the existence and stability properties of multipeaked solitons in a defocusing Kerr medium with an imprinted complex optical lattice featuring a parity-time (PT) symmetry. Various families of soliton solutions with a different number of peaks are found in the first finite gap of the lattice. Linear stability analysis corroborated by direct propagation simulations reveals that multipeaked gap solitons can propagate stably in a wide range, provided that their propagation constant exceeds a critical value. Our findings demonstrate, for the first time, the existence of stable multipeaked gap solitons in a PT-symmetric lattice. PMID:23114357

Li, Chunyan; Huang, Changming; Liu, Haidong; Dong, Liangwei

2012-11-01

134

Symmetric extension for lifted filter banks and obstructions to reversible implementation  

Microsoft Academic Search

Abstract Symmetric pre-extension is a standard approach to boundary handling for finite-length in- put vectors with linear phase filter banks. It works with both conventional linear imple- mentations and so-called reversible, or integer-to-integer, implementations of odd-length linear phase (whole-sample symmetric) filter banks. In comparison, significant di culties arise when using symmetric,pre-extension on reversible filter banks with even-length (half- sample symmetric)

Brendt Wohlberg; Christopher M. Brislawn

2008-01-01

135

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.

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

2012-01-01

136

Bis(arene) Actinide Sandwich Complexes, (eta6-C6H3R3)2An: Linear or bent?  

SciTech Connect

The syntheses of the sandwich complexes ferrocene, (n5-C5H5)2-Fe, in 1951 and uranocene, (n8-C8H8)2U, in 1968 ushered in the modern eras of organotransition metal and organoactinide chemistry, respectively. Ferrocene and uranocene are examples of linear sandwich complexes, that is, those in which the (ring centroid)-M-(ring centroid) angle (denoted 0) is 180 degrees. In the case of (n5-C5H5)2M chemistry, a number of bent (0 < 180 degrees) complexes are known when M is a main-group or rare-earth element. The explanation for the bent structures of these complexes has been the subject of some debate concerning the relative importance of covalent, electrostatic, and steric interactions.

Li, Jun (Ohio State University); Bursten, Bruce E. (Ohio State University)

1999-11-03

137

Tuneable intramolecular intermetallic interactions as a new tool for programming linear heterometallic 4f-4f complexes.  

PubMed

Statistical mechanics predicts that the design of pure organized heteropolymetallic chains of metal ions bound to linear receptors depends on controlled deviations from the mixing rule DeltaE(MiMj) = 1/2 (DeltaE(MiMi) + DeltaE(MjMj)), whereby DeltaE(MiMj) is the intramolecular intermetallic interaction between neighboring metal i and metal j along the receptor. A thorough investigation of linear polymetallic trivalent lanthanide triple-stranded helicates shows that such deviations are amplified by an increase in the nuclearity of the final complexes and are thus easily evidenced in the tetranuclear heterobimetallic helicates [La(4-y)Lu(y)(L6)3](12+) (y = 0-4). The chemical and physical origins of this unprecedented behavior are discussed together with its practical consequences for programming pure heteropolymetallic 4f-4f complexes. PMID:17915861

Dalla-Favera, Natalia; Hamacek, Josef; Borkovec, Michal; Jeannerat, Damien; Ercolani, Gianfranco; Piguet, Claude

2007-10-04

138

Symmetric Auslander and Bass categories  

NASA Astrophysics Data System (ADS)

We define the symmetric Auslander category A^s(R) to consist of complexes of projective modules whose left- and right-tails are equal to the left- and right tails of totally acyclic complexes of projective modules. The symmetric Auslander category contains A(R), the ordinary Auslander category. It is well known that A(R) is intimately related to Gorenstein projective modules, and our main result is that A^s(R) is similarly related to what can reasonably be called Gorenstein projective homomorphisms. Namely, there is an equivalence of triangulated categories: \\underline{GMor}(R) --> A^s(R) / K^b(Prj R). Here \\underline{GMor}(R) is the stable category of Gorenstein projective objects in the abelian category Mor(R) of homomorphisms of R-modules, and K^b(Prj R) is the homotopy category of bounded complexes of projective R-modules. This result is set in the wider context of a theory for A^s(R) and B^s(R), the symmetric Bass category which is defined dually.

Jørgensen, Peter; Kato, Kiriko

2011-03-01

139

Order Selection of the Linear Mixing Model for Complex-Valued FMRI Data  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) data are originally acquired as complex-valued images, which motivates the use\\u000a of complex-valued data analysis methods. Due to the high dimension and high noise level of fMRI data, order selection and\\u000a dimension reduction are important procedures for multivariate analysis methods such as independent component analysis (ICA).\\u000a In this work, we develop a complex-valued order selection

Wei Xiong; Yi-Ou Li; Nicolle Correa; Xi-Lin Li; Vince D. Calhoun; Tülay Adal?

140

Non-linear EEG synchronization during observation and execution of simple and complex sequential finger movements  

Microsoft Academic Search

The main aim of this study was to examine the temporal aspects of neuronal changes during the observation and execution of\\u000a simple and complex tasks to gain a greater understanding of the mirror neuron system’s involvement in complex motor tasks.\\u000a Eleven right-handed subjects observed simple and complex finger movement sequences. Electroencephalograms were recorded from\\u000a 19 electrodes. Activity was considered in

Claire Calmels; Magaly Hars; Paul Holmes; Gilbert Jarry; Cornelis J. Stam

2008-01-01

141

Conformally symmetric traversable wormholes  

SciTech Connect

Exact solutions of traversable wormholes are found under the assumption of spherical symmetry and the existence of a nonstatic conformal symmetry, which presents a more systematic approach in searching for exact wormhole solutions. In this work, a wide variety of solutions are deduced by considering choices for the form function, a specific linear equation of state relating the energy density and the pressure anisotropy, and various phantom wormhole geometries are explored. A large class of solutions impose that the spatial distribution of the exotic matter is restricted to the throat neighborhood, with a cutoff of the stress-energy tensor at a finite junction interface, although asymptotically flat exact solutions are also found. Using the 'volume integral quantifier', it is found that the conformally symmetric phantom wormhole geometries may, in principle, be constructed by infinitesimally small amounts of averaged null energy condition violating matter. Considering the tidal acceleration traversability conditions for the phantom wormhole geometry, specific wormhole dimensions and the traversal velocity are also deduced.

Boehmer, Christian G.; Harko, Tiberiu; Lobo, Francisco S. N. [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 2EG (United Kingdom); Department of Physics and Center for Theoretical and Computational Physics, University of Hong Kong, Pok Fu Lam Road, Hong Kong (China); Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 2EG, United Kingdom and Centro de Astronomia e Astrofisica da Universidade de Lisboa, Campo Grande, Ed. C8 1749-016 Lisbon (Portugal)

2007-10-15

142

A dense out-of-core solver (DOCS) for complex-valued linear systems  

SciTech Connect

Dense systems of linear equations are quite common in many science and engineering applications. Such linear systems place extreme storage and computational demands on computer resources and, in many cases, may severely limit the subsequent analysis. A dense out-of-core solver (DOCS) that operates on a partitioned coefficient matrix can reduce the in-core storage requirements of the linear system while spreading the associated computational burden over multiple processors (which reduces run time as well). In this report, I describe a DOCS that operates on a partitioned coefficient matrix that maybe distributed over multiple external storage devices. I have implemented this solver using Message-Passing Interface (MPI) protocols. This report presents petiormance data from a series of run time trials that compare the run time of both sequential and parallel implementations of the DOCS.

Lee, Cullen E.

1998-09-01

143

Complex-grid spectral algorithms for inviscid linear instability of boundary-layer flows  

Microsoft Academic Search

We present a suite of algorithms designed to obtain accurate numerical solutions of the generalised eigenvalue problem governing inviscid linear instability of boundary-layer type of flow in both the incompressible and compressible regimes on planar and axisymmetric curved geometries. The large gradient problems which occur in the governing equations at critical layers are treated by diverting the integration path into

V. Theofilis; A. Karabis; S. J. Shaw

2003-01-01

144

Algorithm of pulse position identification of complex wave form taken by linear CCD sensor  

Microsoft Academic Search

According to triangulation principle, optical mechanical and electrical structure of the geometrical parameters of the railway over head contact net auto-measuring equipment based on linear CCD sensors is proposed. For abnormal pulse wave form problem caused by each block of air multi-target, it proposed that the signal, in turn, should be done the following: normalization, a differential, quadratic differential, amplitude

Fubao Lil; Zhongke Li; Dexi Wang; Qin Li

2010-01-01

145

A comparative study of some red- and blue-shifted linear H-bonded complexes of N2.  

PubMed

Bond length changes, harmonic vibrational frequency shifts, and changes in the proton magnetic shielding of HX and HKrX (X = F, Cl) on complexation with N2 to form the linear red-shifted N2 ... HX and linear blue-shifted N2 ... HKrX complexes were determined by ab initio computations, with and without counterpoise correction, at the SCF and MP2(full) levels of theory using a 6-311++G(2d,2p) basis set. The MP2 computations agree with predictions from a perturbation theory model involving the first and second derivatives of the interaction energy with respect to displacement of the H--X and H--Kr bond lengths from their equilibrium values in the isolated monomers. The theoretical results agree qualitatively with the experimentally observed frequency shifts, with near quantitative agreement for N2 ... HKrCl. The characteristic downfield shift of the isotropic proton magnetic resonance in the red-shifted complexes was obtained, but for the blue-shifted complexes, the proton NMR shifts to higher fields. PMID:17573674

McDowell, Sean A C

2008-01-30

146

Symmetric Continued Fractions  

NASA Astrophysics Data System (ADS)

Explicit formulae for continued fractions with symmetric patterns in their partial quotients are constructed in the field of formal power series. Similar to the work of Cohn in 1996, which generalized the so-called folding lemma to ?-fold symmetry, the notion of ?-duplicating symmetric continued fractions is investigated using a modification of the 1995 technique due to Clemens, Merrill and Roeder.

Panprasitwech, Oranit; Laohakosol, Vichian; Chaichana, Tuangrat

2010-11-01

147

BiCGstab(ell) for Linear Equations involving Unsymmetric Matrices with Complex Spectrum  

Microsoft Academic Search

. For a number of linear systems of equations arising from realistic problems, using theBi-CGSTAB algorithm of van der Vorst [17] to solve these equations is very attractive. Unfortunately,for a large class of equations, where, for instance, Bi-CG performs well, the convergence of BiCGSTABstagnates. This was observed specifically in case of discretized advection dominated PDE's.The stagnation is due to the

Gerard Sleijpen; Diederik Fokkema

1993-01-01

148

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

SciTech Connect

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 existing PP-LFERs for pure solvents using either a volume-fraction weighted sum of partitioning coefficients K (linear model, R{sup 2} = 0.983, root-mean-squared error (rmse) = 0.23) or a volume-fraction weighted sum of log K (log linear model, R{sup 2} = 0.976, rmse = 0.28). Using the linear model, estimations were, in most cases, within a factor of 2 from the experimental values, regardless of the type of compounds and the presence of a fuel additive. In contrast, the log linear model considerably underestimated partitioning coefficients in the presence of strong solute-solvent hydrogen bonding. For coal tar-water partitioning coefficients (K{sub coal tar/w}), new PP-LFER equations were calculated based on experimental log K{sub coal tar/w} values of 35 compounds. The resulting regression equation was log K{sub coal tar/w} = 0.40({+-}0.33) + 0.34({+-}0.32)E + 0.61({+-}0.57)S - 0.55({+-}0.61)A - 5.07({+-}0.61)B + 3.22({+-}0.35)V with the rmse equal to 0.21, where E, S, A, B, and V are Abraham's solute descriptors. Partitioning coefficients for phenol and alcohols, were closer to the experimental values than to those estimated by the SP-LFER approach with octanol-water partitioning coefficients. The values of the coefficients also provide insight into the properties of coal tar in terms of molecular interactions with solutes. 45 refs., 5 figs., 4 tabs.

Satoshi Endo; Torsten C. Schmidt [Eberhard-Karls-University Tuebingen, Tuebingen (Germany). Center for Applied Geoscience (ZAG)

2006-01-15

149

Blended response algorithms for linear fluctuation-dissipation for complex nonlinear dynamical systems  

NASA Astrophysics Data System (ADS)

In a recent paper the authors developed and tested two novel computational algorithms for predicting the mean linear response of a chaotic dynamical system to small changes in external forcing via the fluctuation-dissipation theorem (FDT): the short-time FDT (ST-FDT), and the hybrid Axiom A FDT (hA-FDT). Unlike the earlier work in developing fluctuation-dissipation theorem-type computational strategies for chaotic nonlinear systems with forcing and dissipation, these two new methods are based on the theory of Sinai-Ruelle-Bowen probability measures, which commonly describe the equilibrium state of such dynamical systems. These two algorithms take into account the fact that the dynamics of chaotic nonlinear forced-dissipative systems often reside on chaotic fractal attractors, where the classical quasi-Gaussian (qG-FDT) approximation of the fluctuation-dissipation theorem often fails to produce satisfactory response prediction, especially in dynamical regimes with weak and moderate degrees of chaos. It has been discovered that the ST-FDT algorithm is an extremely precise linear response approximation for short response times, but numerically unstable for longer response times. On the other hand, the hA-FDT method is numerically stable for all times, but is less accurate for short times. Here we develop blended linear response algorithms, by combining accurate prediction of the ST-FDT method at short response times with numerical stability of qG-FDT and hA-FDT methods at longer response times. The new blended linear response algorithms are tested on the nonlinear Lorenz 96 model with 40 degrees of freedom, chaotic behaviour, forcing, dissipation, and mimicking large-scale features of real-world geophysical models in a wide range of dynamical regimes varying from weakly to strongly chaotic, and to fully turbulent. The results below for the blended response algorithms have a high level of accuracy for the linear response of both mean state and variance throughout all the different chaotic regimes of the 40-mode model. These results point the way towards the potential use of the blended response algorithms in operational long-term climate change projection.

Abramov, Rafail V.; Majda, Andrew J.

2007-12-01

150

Computational study of the linear proton bound ion-molecule complexes of HCNH+ with HCN and HNC.  

PubMed

This work reports the results of a high level ab initio study of the linear proton bound ion-molecule complex of HCNH(+) with HCN and its isomer HNC. The energetics, equilibrium geometries, and predicted equilibrium rotational constants of three strongly interacting ion-molecule complexes are reported from calculations performed at the coupled-cluster calculations including singles, doubles, and perturbative triple excitations (CCSD(T))?aug-cc-pVnZ (n = 2-5) level of theory. Harmonic vibrational frequencies from calculations performed at the CCSD(T)?aug-cc-pVnZ (n = 2-4) level of theory are presented. Additional calculations are performed at the CCSD(T)-F12b?VnZ-F12 level of theory, and the associated energetics, equilibrium geometries, and equilibrium spectroscopic properties are reported. Anharmonicity is treated with the vibrational configuration interaction method, and the predicted anharmonic vibrational frequencies are reported. The results of these calculations show that of the four possible linear interactions of HCNH(+) with HCN and HNC, there are three strongly interacting proton bound complexes. Further, the study presents results that the fourth possible interaction provides the basis for a novel HNC to HCN isomerization pathway in the interstellar medium. PMID:23822300

Eric Cotton, C; Francisco, Joseph S; Klemperer, William

2013-07-01

151

Developing Fuzzy Expert Systems Models for Supply Chain Complex Problem: A Comparison with Linear Programming  

Microsoft Academic Search

Supply chain management (SCM) system endeavors to achieve global optimum solution(s) in supply network problems. SCM systems are mostly large-scale and are recognized as complex systems. This paper concentrates on supply chain system modeling with fuzzy expert systems (FES). The FES is developed based on the knowledge and information of the experts in an automotive supply chain. Then the results

M. H. Fazel Zarandi; Soroosh Saghiri

2006-01-01

152

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

153

Multifrontal parallel distributed symmetric and unsymmetric solvers  

Microsoft Academic Search

We consider the solution of both symmetric and unsymmetric systems of sparse linear equations. A new parallel distributed memory multifrontal approach is described. To handle numerical pivoting efficiently, a parallel asynchronous algorithm with dynamic scheduling of the computing tasks has been developed. We discuss some of the main algorithmic choices and compare both implementation issues and the performance of the

P. R. Amestoy; I. S. Duff; J.-Y. L'Excellent

2000-01-01

154

Reducing the bandwidth of sparse symmetric matrices  

Microsoft Academic Search

The finite element displacement method of analyzing structures involves the solution of large systems of linear algebraic equations with sparse, structured, symmetric coefficient matrices. There is a direct correspondence between the structure of the coefficient matrix, called the stiffness matrix in this case, and the structure of the spatial network delineating the element layout. For the efficient solution of these

E. Cuthill; J. McKee

1969-01-01

155

Synthesis and Characterization of a Linear [Mn3(O2CMe)4(py)8]2+ Complex  

PubMed Central

Two new compounds that consist of the linear trinuclear manganese(II) cation [Mn3(O2CMe)4(py)8]2+ cocrystallizing with different counteranions (I3?, [1]; ClO4?, [2]) are reported. Complex 1 was prepared from the reaction of [Mn(O2CMe)2] · 4H2O with I2 in MeCO2H/py, whereas complex 2 was isolated from the reaction of [Mn3O(O2CMe)6(py)3] · py with [Mn(ClO4)2] · 6H2O in MeCN/py. The crystal structures of both compounds were determined by single crystal X-ray crystallography. Magnetic susceptibility studies that were performed in microcrystalline powder of 1 in the 2–300?K range revealed the presence of antiferromagnetic exchange interactions that resulted in an S = 5/2 ground spin state.

Moushi, Eleni E.; Kizas, Christos; Nastopoulos, Vassilios; Tasiopoulos, Anastasios J.

2010-01-01

156

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

NASA Astrophysics Data System (ADS)

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

Castrillón López, M.; Luján, I.

2013-11-01

157

PT-Symmetric Quantum Field Theory  

SciTech Connect

In 1998 it was discovered that the requirement that a Hamiltonian be Dirac Hermitian (H = H{sup {dagger}}) can be weakened and generalized to the requirement that a Hamiltonian be PT symmetric ([H,PT] = 0); that is, invariant under combined space reflection and time reversal. Weakening the constraint of Hermiticity allows one to consider new kinds of physically acceptable Hamiltonians and, in effect, it amounts to extending quantum mechanics from the real (Hermitian) domain into the complex domain. Much work has been done on the analysis of various PT-symmetric quantum-mechanical models. However, only very little analysis has been done on PT-symmetric quantum-field-theoretic models. Here, we describe some of what has been done in the context of PT-symmetric quantum field theory and describe some possible fundamental applications.

Bender, Carl M. [Physics Department, Washington University, St. Louis, MO 63130 (United States)

2011-09-22

158

PT-Symmetric Quantum Field Theory  

NASA Astrophysics Data System (ADS)

In 1998 it was discovered that the requirement that a Hamiltonian be Dirac Hermitian (H = H†) can be weakened and generalized to the requirement that a Hamiltonian be PT symmetric ([H,PT] = 0) that is, invariant under combined space reflection and time reversal. Weakening the constraint of Hermiticity allows one to consider new kinds of physically acceptable Hamiltonians and, in effect, it amounts to extending quantum mechanics from the real (Hermitian) domain into the complex domain. Much work has been done on the analysis of various PT-symmetric quantum-mechanical models. However, only very little analysis has been done on PT-symmetric quantum-field-theoretic models. Here, we describe some of what has been done in the context of PT-symmetric quantum field theory and describe some possible fundamental applications.

Bender, Carl M.

2011-09-01

159

Noncommutative spherically symmetric spaces  

SciTech Connect

We examine some noncommutative spherically symmetric spaces in three space dimensions. A generalization of Snyder's noncommutative (Euclidean) space allows the inclusion of the generator of dilations into the defining algebra of the coordinate and rotation operators. We then construct a spherically symmetric noncommutative Laplacian on this space having the correct limiting spectrum. This is presented via a creation and annihilation operator realization of the algebra, which may lend itself to a truncation of the Hilbert space.

Murray, Sean; Govaerts, Jan [Centre for Cosmology, Particle Physics and Phenomenology, Universite catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve (Belgium); Centre for Cosmology, Particle Physics and Phenomenology, Universite catholique de Louvain, Chemin du Cyclotron 2, B-1348 Louvain-la-Neuve (Belgium) and International Chair in Mathematical Physics and Applications, University of Abomey-Calavi, 072 B. P. 50, Cotonou (Benin)

2011-01-15

160

Twin salphen: asymmetric heterodinuclear complexes {M(a)M(b)L | M(a), M(b) = Ni, Cu, Zn} of a symmetrically fused salphen ligand.  

PubMed

Heterodinuclear complexes of a fully pi-conjugated salphen ligand were efficiently synthesized with arbitrary combinations of Ni(II), Cu(II), and Zn(II). The UV-vis spectra of the heterodinuclear complexes were approximately represented by a simple average of the spectra of the corresponding homodinuclear complexes. Systematic analysis of the spectra highlighted weak intracomplex interactions through the pi-conjugated system of the ligand. PMID:19831386

Houjou, Hirohiko; Ito, Muneyuki; Araki, Koji

2009-11-16

161

Controlled loading of cryoprotectants (CPAs) to oocyte with linear and complex CPA profiles on a microfluidic platform†  

PubMed Central

Oocyte cryopreservation has become an essential tool in the treatment of infertility by preserving oocytes for women undergoing chemotherapy. However, despite recent advances, pregnancy rates from all cryopreserved oocytes remain low. The inevitable use of the cryoprotectants (CPAs) during preservation affects the viability of the preserved oocytes and pregnancy rates either through CPA toxicity or osmotic injury. Current protocols attempt to reduce CPA toxicity by minimizing CPA concentrations, or by minimizing the volume changes via the step-wise addition of CPAs to the cells. Although the step-wise addition decreases osmotic shock to oocytes, it unfortunately increases toxic injuries due to the long exposure times to CPAs. To address limitations of current protocols and to rationally design protocols that minimize the exposure to CPAs, we developed a microfluidic device for the quantitative measurements of oocyte volume during various CPA loading protocols. We spatially secured a single oocyte on the microfluidic device, created precisely controlled continuous CPA profiles (step-wise, linear and complex) for the addition of CPAs to the oocyte and measured the oocyte volumetric response to each profile. With both linear and complex profiles, we were able to load 1.5 M propanediol to oocytes in less than 15 min and with a volumetric change of less than 10%. Thus, we believe this single oocyte analysis technology will eventually help future advances in assisted reproductive technologies and fertility preservation.

Heo, Yun Seok; Lee, Ho-Joon; Hassell, Bryan A.; Irimia, Daniel; Toth, Thomas L.; Elmoazzen, Heidi; Toner, Mehmet

2013-01-01

162

A new generation of metal string complexes: structure, magnetism, spectroscopy, theoretical analysis, and single molecular conductance of an unusual mixed-valence linear [Ni5]8+ complex.  

PubMed

Two new linear pentanickel complexes [Ni5(bna)4(Cl)2][PF6]2 (1) and [Ni5(bna)4(Cl)2][PF6]4 (2; bna=binaphthyridylamide), were synthesized and structurally characterized. A derivative of 1, [Ni5(bna)4(NCS)2][NCS]2 (3), was also isolated for the purpose of the conductance experiments carried out in comparison with [Ni5(tpda)4(NCS)2] (4; tpda=tripyridyldiamide). The metal framework of complex 2 is a standard [Ni5]10+ core, isoelectronic with that of [Ni5(tpda)4Cl2] (5). Also as in 5, complex 2 has an antiferromagnetic ground state (J=-15.86 cm(-1)) resulting from a coupling between the terminal nickel atoms, both in high-spin sate (S=1). Complex 1 displays the first characterized linear nickel framework in which the usual sequence of NiII atoms has been reduced by two electrons. Each dinickel unit attached to the naphthyridyl moieties is assumed to undergo a one-electron reduction, whereas the central nickel formally remains NiII. DFT calculations suggest that the metal framework of the mixed-valence complex 1 should be described as intermediate between a localized picture corresponding to NiII-NiI-NiII-NiI-NiII and a fully delocalized model represented as (Ni2)3+-NiII-(Ni2)3+. Assuming the latter model, the ground state of 1 results from an antiferromagnetic coupling (J=-34.03 cm(-1)) between the two (Ni2)3+ fragments, considered each as a single magnetic centre (S=3/2). An intervalence charge-transfer band is observed in the NIR spectrum of 1 at 1186 nm, suggesting, in accordance with DFT calculations, that 1 should be assigned to Robin-Day class II of mixed-valent complexes. Scanning tunnelling microscopy (STM) methodology was used to assess the conductance of single molecules of 3 and 4. Compound 3 was found approximately 40% more conductive than 4, a result that could be assigned to the electron mobility induced by mixed-valency in the naphthyridyl fragments. PMID:17847146

Liu, Isiah Po-Chun; Bénard, Marc; Hasanov, Hasan; Chen, I-Wen Peter; Tseng, Wei-Hsiang; Fu, Ming-Dung; Rohmer, Marie-Madeleine; Chen, Chun-hsien; Lee, Gene-Hsiang; Peng, Shie-Ming

2007-01-01

163

PT-symmetric optical lattices  

SciTech Connect

The basic properties of Floquet-Bloch (FB) modes in parity-time (PT)-symmetric optical lattices are examined in detail. Due to the parity-time symmetry of such complex periodic potentials, the corresponding FB modes are skewed (nonorthogonal) and nonreciprocal. The conjugate pairs of these FB modes are obtained by reflecting both the spatial coordinate and the Bloch momentum number itself. The orthogonality conditions are analytically derived for a single cell, for both a finite and an infinite lattice. Some of the peculiarities associated with the diffraction dynamics in PT lattices such as nonreciprocity, power oscillations, and phase dislocations, are also examined.

Makris, Konstantinos G.; El-Ganainy, Ramy; Christodoulides, Demetrios N.; Musslimani, Z. H. [College of Optics/CREOL, University of Central Florida, Orlando, Florida 32816 (United States); Department of Mathematics, Florida State University Tallahassee, Florida 32306-4510 (United States)

2010-06-15

164

Synthesis, characterization and electrochemical behaviour of cobalt(II) and cobalt(III):O 2 ? complexes, respectively, with linear and tripodal tetradentate ligands derived from Schiff bases  

Microsoft Academic Search

New octahedral cobalt complexes with linear and tripodal tetradentate ligands derived from Schiff bases have been synthesized and characterized using elemental analysis, molar conductance, IR spectra, magnetic measurements, electronic and ESR spectra.The experimental results support the binding of linear ligands with two N and two O donor sites to cobalt ion. They show a square planar geometry and tripodal ligands

S. Djebbar-Sid; O Benali-Baitich; J. P Deloume

2001-01-01

165

An Efficient Computation of LSP Frequencies Using Modified Complex-Free Ferrari Formula  

Microsoft Academic Search

In this paper, an efficient algorithm for computing line spectrum pair (LSP) frequencies from linear prediction coefficients\\u000a is described. Based on the decimation-in-degree algorithm proposed by Wu and Chen, this paper modifies the Ferrari formula\\u000a to reduce the computational complexity of finding the roots, i.e., LSPs, of the symmetric and anti-symmetric polynomials.\\u000a By the use of this modified complex-free Ferrari

Shi-huang Chen; Yaotsu Chang; Jiun-ching Ruan

2008-01-01

166

Multi-Party Privacy-Preserving Set Intersection with Quasi-Linear Complexity  

NASA Astrophysics Data System (ADS)

Secure computation of the set intersection functionality allows n parties to find the intersection between their datasets without revealing anything else about them. An efficient protocol for such a task could have multiple potential applications in commerce, health care, and security. However, all currently known secure set intersection protocols for n>2 parties have computational costs that are quadratic in the (maximum) number of entries in the dataset contributed by each party, making secure computation of the set intersection only practical for small datasets. In this paper, we describe the first multi-party protocol for securely computing the set intersection functionality with both the communication and the computation costs that are quasi-linear in the size of the datasets. For a fixed security parameter, our protocols require O(n2k) bits of communication and Õ(n2k) group multiplications per player in the malicious adversary setting, where k is the size of each dataset. Our protocol follows the basic idea of the protocol proposed by Kissner and Song, but we gain efficiency by using different representations of the polynomials associated with users' datasets and careful employment of algorithms that interpolate or evaluate polynomials on multiple points more efficiently. Moreover, the proposed protocol is robust. This means that the protocol outputs the desired result even if some corrupted players leave during the execution of the protocol.

Cheon, Jung Hee; Jarecki, Stanislaw; Seo, Jae Hong

167

A HLL-Rankine–Hugoniot Riemann solver for complex non-linear hyperbolic problems  

NASA Astrophysics Data System (ADS)

We present a new HLL-type approximate Riemann solver that aims at capturing any isolated discontinuity without necessitating extensive characteristic analysis of governing partial differential equations. This property is especially attractive for complex hyperbolic systems with more than two equations. Following Linde's (2002) approach [6], we introduce a generic middle wave into the classical two-state HLL solver. The property of this third wave is typified by the way of a "strength indicator" that is derived from polynomial considerations. The polynomial that constitutes the basis of the procedure is made non-oscillatory by an adapted fourth-order WENO algorithm (CWENO4). This algorithm makes it possible to derive an expression for the strength indicator. According to the size of this latter parameter, the resulting solver (HLL-RH), either computes the multi-dimensional Rankine–Hugoniot equations if an isolated discontinuity appears in the Riemann fan, or asymptotically tends towards the two-state HLL solver if the solution is locally smooth. The asymptotic version of the HLL-RH solver is demonstrated to be positively conservative and entropy satisfying in its first-order multi-dimensional form provided that a relevant and not too restrictive CFL condition is considered; specific limitations of the conservative increments of the numerical solution and a suited entropy condition enable to maintain these properties in its high-order version.With a monotonicity-preserving algorithm for the time integration, the numerical method so generated, is third order in time and fourth-order accurate in space for the smooth part of the solution; moreover, the scheme is stable and accurate when capturing a shock wave, whatever the complexity of the underlying differential system.Extensive numerical tests for the one- and two-dimensional Euler equation of gas dynamics and comparisons with classical Godunov-type methods help to point out the potentialities and insufficiencies of the method.

Guy, Capdeville

2013-10-01

168

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.

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

2001-01-01

169

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

170

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

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

2013-04-22

171

Copper(II) complexes of symmetrical and unsymmetrical tetradentate Schiff base ligands incorporating 1-benzoylacetone: Synthesis, crystal structures and electrochemical behavior  

Microsoft Academic Search

Three new copper(II) complexes [CuL1]2(ClO4)2 (1), [CuL2]ClO4 (2) and [CuL3] (3) with three Schiff base ligands [HL1=1-phenyl-3-{3-[(pyridin-2-ylmethylene)-amino]-propylimino}-butan-1-one, HL2=1-phenyl-3-[3-(1-pyridin-2-yl-ethylideneamino)-propylimino]-butan-1-one and H2L3=3-[3-(1-methyl-3-oxo-3-phenyl-propylideneamino)-propylimino]-1-phenyl-butan-1-one] have been synthesized and structurally characterized by X-ray crystallography. The mono-negative tetradentate asymmetric Schiff base ligands (L1)? and (L2)? are chelated in complexes 1 and 2 to form square planar copper(II) complexes. In complex 1, the two units are associated

Biswarup Sarkar; Gabriele Bocelli; Andrea Cantoni; Ashutosh Ghosh

2008-01-01

172

Isospecific polymerization of 1-hexene by C1-symmetric half-metallocene dimethyl complexes of group 4 metals with bidentate N-substituted iminomethylpyrrolyl ligands.  

PubMed

Non-bridged half-metallocene dimethyl complexes of group 4 metals 2a-4a with an N-4-methoxyphenyl(iminomethyl)pyrrolyl ligand 1a were synthesized and characterized by NMR spectroscopy and X-ray analysis. Upon activation with [Ph3C][B(C6F5)4], these complexes became active catalysts for the polymerization of 1-hexene. A series of hafnium complexes with various N-substituents on the imine group of ligands 1b-1g were also prepared and applied as catalysts for 1-hexene polymerization. The activation parameters for the exchange process between the two methyl groups bound to the metal for Cp*MMe2(R-pyr) complexes were estimated by NMR shape analysis at various temperatures. The findings indicated that the transition state of the ligand flipping process might be associated with the isoselectivity of the polymerization reaction. PMID:23235804

Yasumoto, Takahiro; Yamamoto, Keishi; Tsurugi, Hayato; Mashima, Kazushi

2012-12-12

173

Symmetry in Integer Linear Programming  

Microsoft Academic Search

\\u000a An integer linear program (ILP) is symmetric if its variables can be permuted without changing the structure of the problem.\\u000a Areas where symmetric ILPs arise range from applied settings (scheduling on identical machines), to combinatorics (code construction),\\u000a and to statistics (statistical designs construction). Relatively small symmetric ILPs are extremely difficult to solve using\\u000a branch-and-cut codes oblivious to the symmetry in

François Margot

174

Synthesis of linear polyamines with different amine spacings and their ability to form dsDNA/siRNA complexes suitable for transfection.  

PubMed

In this paper we report on the synthesis of diversified linear polyamine architectures with different chain lengths and compositions and their interaction with phosphate groups of DNA/siRNA. The polyplex formation between model nucleotide (dsDNA) and these linear polyamines has been determined at different nitrogen to phosphorus (N/P) ratios using small-angle neutron scattering (SANS) and atomic force microscopy (AFM) techniques. AFM images showed that while linear poly(ethylene imine) (PEI)/DNA complex results in bigger spherical aggregates, poly(propylene imine)s forms torroid and cigar shaped structures upon complexation with DNA. The poly(butylene imine)s (LPBI)s form compact and soluble DNA complexes with a radii range of R(g) = 15-30 nm. Among the studied linear polyamines, the LPBIs did show the best transfection efficiency. PMID:20715130

Fischer, Wiebke; Brissault, Blandine; Prévost, Sylvain; Kopaczynska, Marta; Andreou, Ioanna; Janosch, Andrea; Gradzielski, Michael; Haag, Rainer

2010-09-01

175

A perfect linear Cu-NNN-Cu unit inside the cryptand cavity and perchlorate entrapment within the channel formed by the cascade complex.  

PubMed

Dicopper complexes of bis-tren cryptand L1 having 1,4-xylyl spacers, becoming a potential receptor for perfect linear recognition of N3-, generate a Cu-NNN-Cu unit inside the cryptand cavity. Solid-state packing of this cascade complex shows the formation of a thorough channel which encapsulate perchlorate anion within the channel. PMID:17140207

Ravikumar, I; Suresh, E; Ghosh, Pradyut

2006-12-11

176

The symmetric parabolic resonance  

NASA Astrophysics Data System (ADS)

The parabolic resonance instability emerges in diverse applications ranging from optical systems to simple mechanical ones. It appears persistently in p-parameter families of near-integrable Hamiltonian systems with n degrees of freedom provided n + p >= 3. Here we study the simplest (n = 2, p = 1) symmetric case. The structure and the phase-space volume of the corresponding instability zones are characterized. It is shown that the symmetric case has six distinct non-degenerate normal forms, and two degenerate ones. In the regular cases, the instability zone has the usual O(\\sqrt{\\varepsilon}) extent in the action direction. However, the phase-space volume of this zone is found to be polynomial in the perturbation parameter ? (and not exponentially small as in the elliptic resonance case). Finally, the extent of the instability zone in some of the degenerate cases is explored. Three applications in which the symmetric parabolic resonance arises are presented and analysed.

Rom-Kedar, V.; Turaev, D.

2010-06-01

177

Complexation of Mercury(II) in Soil Organic Matter: EXAFS Evidence for Linear Two-Coordination with Reduced Sulfur Groups  

SciTech Connect

The chemical speciation of inorganic mercury (Hg) is to a great extent controlling biologically mediated processes, such as mercury methylation, in soils, sediments, and surface waters. Of utmost importance are complexation reactions with functional groups of natural organic matter (NOM), indirectly determining concentrations of bioavailable, inorganic Hg species. Two previous extended X-ray absorption fine structure (EXAFS) spectroscopic studies have revealed that reduced organic sulfur (S) and oxygen/nitrogen (O/N) groups are involved in the complexation of Hg(II) to humic substances extracted from organic soils. In this work, covering intact organic soils and extending to much lower concentrations of Hg than before, we show that Hg is complexed by two reduced organic S groups (likely thiols) at a distance of 2.33 Angstroms in a linear configuration. Furthermore, a third reduced S (likely an organic sulfide) was indicated to contribute with a weaker second shell attraction at a distance of 2.92-3.08 Angstroms. When all high-affinity S sites, corresponding to 20-30% of total reduced organic S, were saturated, a structure involving one carbonyl-O or amino-N at 2.07 Angstroms and one carboxyl-O at 2.84 Angstroms in the first shell, and two second shell C atoms at an average distance of 3.14 Angstroms, gave the best fit to data. Similar results were obtained for humic acid extracted from an organic wetland soil. We conclude that models that are in current use to describe the biogeochemistry of mercury and to calculate thermodynamic processes need to include a two-coordinated complexation of Hg(II) to reduced organic sulfur groups in NOM in soils and waters.

Skyllberg,U.; Bloom, P.; Qian, J.; Lin, C.; Bleam, W.

2006-01-01

178

Split Photosystem Protein, Linear-Mapping Topology, and Growth of Structural Complexity in the Plastid Genome of Chromera velia.  

PubMed

The canonical photosynthetic plastid genomes consist of a single circular-mapping chromosome that encodes a highly conserved protein core, involved in photosynthesis and ATP generation. Here, we demonstrate that the plastid genome of the photosynthetic relative of apicomplexans, Chromera velia, departs from this view in several unique ways. Core photosynthesis proteins PsaA and AtpB have been broken into two fragments, which we show are independently transcribed, oligoU-tailed, translated, and assembled into functional photosystem I and ATP synthase complexes. Genome-wide transcription profiles support expression of many other highly modified proteins, including several that contain extensions amounting to hundreds of amino acids in length. Canonical gene clusters and operons have been fragmented and reshuffled into novel putative transcriptional units. Massive genomic coverage by paired-end reads, coupled with pulsed-field gel electrophoresis and polymerase chain reaction, consistently indicate that the C. velia plastid genome is linear-mapping, a unique state among all plastids. Abundant intragenomic duplication probably mediated by recombination can explain protein splits, extensions, and genome linearization and is perhaps the key driving force behind the many features that defy the conventional ways of plastid genome architecture and function. PMID:23974208

Janouskovec, Jan; Sobotka, Roman; Lai, De-Hua; Flegontov, Pavel; Koník, Peter; Komenda, Josef; Ali, Shahjahan; Prásil, Ondrej; Pain, Arnab; Oborník, Miroslav; Lukes, Julius; Keeling, Patrick J

2013-08-22

179

Complex dynamics of isotropic 4-cyano-4-n-pentylbiphenyl (5CB) in linear and nonlinear dielectric relaxation studies  

NASA Astrophysics Data System (ADS)

A comprehensive presentation of the temperature evolution of ``linear'' and ``nonlinear'' dielectric relaxation in the isotropic phase of nematic liquid crystalline compound 5CB (4-cyano-4-n-pentylbiphenyl) is given. The ``nonlinear'' relaxation is related to the strong pretransitional rise in the lifetime of prenematic fluctuations. The ``linear'' relaxation has a clear non-Debye and non-Arrhenius form. In the immediate vicinity of the nematic clearing point it shows a weak pretransitional anomaly. Results obtained coincide with the complex liquid relaxation pattern found in transient grating optical Kerr effect studies [A. Sengupta and M. D. Fayer, J. Chem. Phys. 102, 4193 (1995); R. Torre et al., Philos. Mag. A 77, 645 (1997)]. The striking similarity to the behavior found in critical, binary mixtures suggests the extension of the ``fluidlike'' hypothesis for the isotropic-nematic transition to dynamic phenomena in the isotropic phase [P. K. Mukherjee. J. Phys.: Condens. Matter 10, 9191 (1998)]. The presence of both glassy and fluidlike features in isotropic 5CB coincides with the recent results of simulation analysis for the system of hard ellipsoids by Latz et al. [Phys. Rev. E 62, 5173 (2000)] and with the novel general picture for liquid-liquid transitions proposed by Tanaka [Phys. Rev. E 62, 6968 (2000)].

Drozd-Rzoska, A.; Rzoska, S. J.

2002-04-01

180

CLASSICAL AREAS OF PHENOMENOLOGY: Generation and classification of robust remote symmetric Dicke states  

Microsoft Academic Search

In this paper, we present an approach to generating arbitrary symmetric Dicke states with distant trapped ions and linear optics. Distant trapped ions can be prepared in the symmetric Dicke states by using two photon-number-resolving detectors and a polarization beam splitter. The atomic symmetric Dicke states are robust against decoherence, for atoms are in a metastable level. We discuss the

Yan-Wu Zhu; Ke-Lin Gao

2008-01-01

181

Braids, shuffles and symmetrizers  

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

182

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

183

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

184

Non-linear model for the kinetics of 10B in blood after BPA-fructose complex infusion  

NASA Astrophysics Data System (ADS)

A numerical model with a memory effect was created to describe the kinetics of 10B in blood after a single 4-dihydroxyborylphenylalanine-fructose complex (BPA-F) infusion in boron neutron capture therapy (BNCT). The model formulation was based on the averaged data from 10 glioma patients from the Brookhaven National Laboratory (BNL) BNCT-trials. These patients received a 2 h i.v. infusion of a BPA-fructose complex that delivered 290 mg BPA/kg body weight. The model was validated by fitting the original BNL patient data and new patient data from the Finnish BNCT-trials. The new 3-parameter non-linear model provided mean absolute differences between the measured and estimated 10B concentrations in blood that were less than 3.9% when used to simulate actual patient irradiations that comprised two irradiation fields separated by a break to reposition the patient. The flexibility of the model was successfully tested with two different infusion protocols. The patient data were modelled with a two-compartment model and a bi-exponential fit for comparison. The 3-parameter model is better than previously described models in predicting the time course of blood 10B concentration after cessation of intravenous infusion of BPA-fructose.

Ryynänen, Päivi; Kangasmäki, Aki; Hiismäki, Pekka; Coderre, Jeffrey; Diaz, Aidnag Z.; Kallio, Merja; Laakso, Juha; Kulvik, Martti; Savolainen, Sauli

2002-03-01

185

Horospherical Cauchy-Radon transform on compact symmetric spaces  

Microsoft Academic Search

Harmonic analysis on noncompact Riemannian symmetric spaces is in a sense equivalent to the theory of the horospherical transform. There are no horospheres on compact symmetric spaces, but we define a complex version of horospherical transform which plays a similar role for the harmonic analysis on them.

Simon Gindikin

2005-01-01

186

Isomorphic Steiner symmetrization  

Microsoft Academic Search

This paper proves that there exist 3 n Steiner symmetrizations that transform any convex set K?R n into an isomorphic Euclidean ball; i.e. if vol( K)= vol( D n) where D n is the standard Euclidean unit ball, then K can be transformed into a body K such that c 1 D n? K? c 2 D n, where c

B. Klartag; V. D. Milman

2003-01-01

187

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

Microsoft Academic Search

Nuclear quantum effects (NQE) on the geometry, energy, and electronic structure of the [CN.L.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

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

2011-01-01

188

Linear Free Energy Relationships for Metal-Ligand Complexation: Bidentate Binding to Negatively-Charged Oxygen Donor Atoms  

PubMed Central

Stability constants for metal complexation to bidentate ligands containing negatively-charged oxygen donor atoms can be estimated from the following linear free energy relationship (LFER): log KML = ?OO(?O log KHL,1 + ?O log KHL,2) where KML is the metal-ligand stability constant for a 1:1 complex, KHL,1 and KHL,2 are the proton-ligand stability constants (the ligand pKa values), and ?O is the Irving-Rossotti slope. The parameter ?OO is metal specific and has slightly different values for 5 and 6 membered chelate rings. LFERs are presented for 21 different metal ions and are accurate to within approximately 0.30 log units in predictions of log KML values. Ligands selected for use in LFER development include dicarboxylic acids, carboxyphenols, and ortho-diphenols. For ortho-hydroxybenzaldehydes, ?-hydroxycarboxylic acids, and ?-ketocarboxylic acids, a modification of the LFER where log KHL,2 is set equal to zero is required. The chemical interpretation of ?OO is that it accounts for the extra stability afforded to metal complexes by the chelate effect. Cu-NOM binding constants calculated from the bidentate LFERs are similar in magnitude to those used in WHAM 6. This LFER can be used to make log KML predictions for small organic molecules. Since natural organic matter (NOM) contains many of the same functional groups (i.e. carboxylic acids, phenols, alcohols), the LFER log KML predictions shed light on the range of appropriate values for use in modeling metal partitioning in natural systems.

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

2011-01-01

189

Theoretical and electrochemical studies on organometallic symmetrical schiff base complexes of Zn(II), Cu(II), Ni(II) and Co(II).  

PubMed

The electronic communication between two redox centres through a Schiff base complex has been investigated in a series of ethylenediimine-bis(1-ferrocenyl-1,3-butanedionate) complexes of Zn(II) 1, Cu(II) 2, Ni(II) 3 and Co(II) 4. Cyclic voltammetry experiments of 1 and 2 exhibit a unique two-electron reversible oxidation wave, whereas in the case of 3 and 4 two and three one-electron oxidation processes are, respectively, observed. These results suggest some electronic interaction between the iron atoms of the ferrocenyl groups. DFT calculations carried out on model complexes show that for all the studied compounds the removal of the first two electrons corresponds to the oxidation processes of the iron centres in the weakly coupled ferrocenyl termini. The electronic communication between the two iron centres increases on going from 1 to 4. Finally, a re-indexation of the bands observed in the UV-Visible spectra has been carried out using TDDFT calculations. PMID:18399232

Fuentealba, Mauricio; Garland, María Teresa; Carrillo, David; Manzur, Carolina; Hamon, Jean-René; Saillard, Jean-Yves

2008-01-01

190

Active and passive symmetrization of Runge-Kutta Lobatto IIIA methods  

NASA Astrophysics Data System (ADS)

Symmetrization of the Runge-Kutta Gauss methods have been shown to be robust in solving stiff linear and nonlinear initial value ordinary differential equations [4]. The most efficient way of applying symmmetrization was found to be passive symmetrization with passive extrapolation. In this paper we investigate symmetrization of the Lobatto IIIA methods. We show numerically that the same strategy of using passive symmetrization applied with passive extrapolation of the Lobbatto IIIA methods is also most efficient in solving the nonlinear problems tested.

Gorgey, A.; Chan, R. P. K.

2012-09-01

191

A linear regression model using triangular fuzzy number coefficients  

Microsoft Academic Search

Fuzzy regression analysis using fuzzy linear models with symmetric triangular fuzzy number coefficients has been formulated earlier. The goal of this regression is to find the coefficients of a proposed model for all given input-output data sets. In this paper, we extend the results of a fuzzy linear regression model that uses symmetric triangular coefficient to one with non-symmetric fuzzy

K. K. Yen; S. Ghoshray; G. Roig

1999-01-01

192

The Fc segment of IgE influences the kinetics of dissociation of a symmetrical bivalent ligand from cyclic dimeric complexes  

SciTech Connect

As part of a systematic effort to determine the features of immunoglobulin E-receptor (IgE-Fc{epsilon}RI) aggregation that are critical for cellular activation, we used fluorescence to examine the dissociation of a soluble bivalent ligand, N,N{prime}-bis[[{epsilon}-[(2,4-dinitrophenyl)amino]caproyl]-L-tyrosyl]-L-cystine ((DCT){sub 2{minus}}cys), from soluble bivalent IgE and its bivalent F(ab{prime}){sub 2} and monovalent Fab{prime} fragments. Cross-linking of Fab{prime} fragments by (DCT){sub 2}-cys is limited to linear dimers, and we find that (DCT){sub 2}-cys dissociation from Fab{prime} occurs with a single kinetic coefficient [(4.2 {plus_minus} 0.6) {times} 10{sup {minus}3}s{sup {minus}1}] that corresponds to the lower of the two kinetic coefficients observed with the bivalent IgE[(4.7 {plus_minus} 0.7) {times} 10{sup {minus}2} s{sup {minus}1} and (4.4 {plus_minus} 0.3) {times} 10{sup {minus}3} s{sup {minus}1}]. Similarly, the lower value is obtained for dissociation of (DCT){sub 2}-cys that is monovalently bound to IgE after incubation with a large excess of the ligand. (DCT){sub 2}-cys can bind to bivalent F(ab{prime}){sub 2} fragments and form a variety of linear and cyclic aggregates, similarly to IgE, but, unlike IgE, we find that dissociation occurs with a single kinetic coefficient similar to that observed for Fab{prime}. We find that IgE and its (Fab{prime}){sub 2} fragments form highly stable cyclic dimer rings with two (DCT){sub 2}-cys. We demonstrate that the kinetic coefficients are independent of enhanced fluorescence quenching observed for bound sites in cyclic dimers. 29 refs., 6 figs., 2 tabs.

Subramanian, K.; Holowka, D.; Baird, B. [Cornell Univ., Ithaca, NY (United States); Goldstein, B. [Los Alamos National Lab., Los Alamos, NM (United States)

1996-04-30

193

Experimental characterization of qutrits using symmetric informationally complete positive operator-valued measurements  

SciTech Connect

Generalized quantum measurements [also known as positive operator-valued measures (POVMs)] are of great importance in quantum information and quantum foundations but are often difficult to perform. We present an experimental approach which can in principle be used to perform arbitrary POVMs in a linear-optical context. One of the most interesting POVMs, the symmetric informationally complete (SIC) POVM, is the most compact set of measurements that can be used to fully describe a quantum state. We use our technique to carry out the first experimental characterization of the state of a qutrit using SIC POVMs. Because of the highly symmetric nature of this measurement, such a representation has the unique property that it permits all other measurement outcomes to be predicted by a simple extension of the classical Bayesian sum rule, making no use of complex amplitudes or Hilbert-space operators. We demonstrate this approach on several qutrit states encoded in single photons.

Medendorp, Z. E. D.; Shalm, L. K.; Steinberg, A. M. [Centre for Quantum Information and Quantum Control and Institute for Optical Sciences, Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario, M5S 1A7 (Canada); Torres-Ruiz, F. A. [Center for Optics and Photonics, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile); Departamento de Ciencias Fisicas, Universidad de La Frontera, Temuco, Casilla 54-D (Chile); Tabia, G. N. M.; Fuchs, C. A. [Perimeter Institute for Theoretical Physics, Waterloo, Ontario, N2L 2Y5 (Canada)

2011-05-15

194

Movement detection based on filter with symmetric impulse response  

Microsoft Academic Search

The continuous-time detection of movement is a time-domain operation. It usually requires lowpass filters ensuring small waveform distortion. To achieve small time- domain distortion, the filters approximating linear phase, such as Bessel and Gaussian filter, are often used. However, these filters have poor selectivity. Both, high selectivity and nearly linear phase are obtained by using the filters with symmetric impulse

Mislav Jordanic; Goran Molnar; Ratko Magjarevic

2011-01-01

195

General DMT optimality of LR-aided linear MIMO-MAC transceivers with worst-case complexity at most linear in sum-rate  

Microsoft Academic Search

In the setting of multiple-access MIMO channels, the work establishes the DMT optimality of lattice-reduction (LR)-aided regularized linear decoders. This is achieved irrespective of the lattice design applied by each user. The decoding algorithms employ efficient solutions to the Nearby Vector Problem with Preprocessing in the presence of a regularized non-Euclidean metric, and in the presence of time-outs. The decoders'

Petros Elia; J. Jalden

2010-01-01

196

Classical symmetric functions in superspace  

Microsoft Academic Search

We present the basic elements of a generalization of symmetric function theory involving functions of commuting and anticommuting (Grassmannian) variables. These new functions, called symmetric functions in superspace, are invariant under the diagonal action of the symmetric group on the sets of commuting and anticommuting variables. In this work, we present the superspace extension of the classical bases, namely, the

Patrick Desrosiers; Luc Lapointe; Pierre Mathieu

2006-01-01

197

Properties of Symmetric Fitness Functions  

Microsoft Academic Search

The properties of symmetric fitness functions are investigated. We show that the search spaces obtained from symmetric functions have the zero-correlation structures between fitness and distance. It is also proven that symmetric functions induce a class of the hardest problems in terms of the epistasis variance and its variants. These analyses suggest that the existing quantitative measures cannot discriminate among

Sung-soon Choi; Yung-keun Kwon; Byung-Ro Moon

2007-01-01

198

A Mn(III) triplesalen-based 1D pearl necklace: exchange interactions and zero-field splittings in a C3-symmetric Mn(III)6 complex.  

PubMed

The reaction of the tert-butyl-substituted triplesalen ligand H(6)talen(t-Bu(2)) with 2.8 equivalents of Mn(OAc)(2) x 4 H(2)O in MeOH in the presence of NaBPh(4) results in the formation of the one-dimensional (1D) coordination polymer {[{(talen(t-Bu(2)))Mn(3)(MeOH)}(2)(mu(2)-OAc)(3)](mu(2)-OAc)}(n)(BPh(4))(2n) ({[Mn(III)(6)](OAc)}(n)(BPh(4))(2n)) which has been characterized by FTIR, elemental analysis, ESI-MS, single-crystal X-ray diffraction and magnetic measurements. The triplesalen ligand (talen(t-Bu(2)))(6-) provides three salen-like coordination compartments bridged in a meta-phenylene arrangement by a phloroglucinol backbone resulting in the trinuclear Mn(III) base unit {(talen(t-Bu(2)))Mn(3)}(3+). Two of these base units are bridged by three inner acetate ligands giving rise to the hexanuclear complex [{(talen(t-Bu(2)))Mn(3)(MeOH)}(2)(mu(2)-OAc)(3)](3+) ([Mn(III)(6)](3+)). These complexes are bridged by a single external acetate to form a 1D chain as pearls in a pearl necklace. Variable temperature-variable field and mu(eff)vs. 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 have been obtained for parameters sets J(1) = -(0.60 +/- 0.15) cm(-1), J(2) = -(1.05 +/- 0.15) cm(-1), and D(Mn) = -(3.0 +/- 0.7) cm(-1) with J(1) describing the exchange through the phloroglucinol backbone and J(2) describing the exchange through the inner acetates. The non-necessity to incorporate the bridging outer acetates correlates with the longer Mn-O bonds. The experimental data can neither be analyzed without incorporating zero-field splitting nor by the application of a single effective spin ground state. PMID:20023950

Glaser, Thorsten; Heidemeier, Maik; Theil, Hubert; Stammler, Anja; Bögge, Hartmut; Schnack, Jürgen

2009-10-07

199

The pneumococcal MgaSpn virulence transcriptional regulator generates multimeric complexes on linear double-stranded DNA  

PubMed Central

The MgaSpn transcriptional regulator contributes to the virulence of Streptococcus pneumoniae. It is thought to be a member of the Mga/AtxA family of global regulators. MgaSpn was shown to activate in vivo the P1623B promoter, which is divergent from the promoter (Pmga) of its own gene. This activation required a 70-bp region (PB activation region) located between both promoters. In this work, we purified an untagged form of the MgaSpn protein, which formed dimers in solution. By gel retardation and footprinting assays, we analysed the binding of MgaSpn to linear double-stranded DNAs. MgaSpn interacted with the PB activation region when it was placed at internal position on the DNA. However, when it was positioned at one DNA end, MgaSpn recognized preferentially the Pmga promoter placed at internal position. In both cases, and on binding to the primary site, MgaSpn spread along the adjacent DNA regions generating multimeric protein–DNA complexes. When both MgaSpn-binding sites were located at internal positions on longer DNAs, electron microscopy experiments demonstrated that the PB activation region was the preferred target. DNA molecules totally or partially covered by MgaSpn were also visualized. Our results suggest that MgaSpn might recognize particular DNA conformations to achieve DNA-binding specificity.

Solano-Collado, Virtu; Lurz, Rudi; Espinosa, Manuel; Bravo, Alicia

2013-01-01

200

LQR-Based least-squares output feedback control of rotor vibrations using the complex mode and balanced realization methods. [Linear-Quadratic-Regulator  

Microsoft Academic Search

The complex mode and balanced realization methods are used separately to obtain reduced-order models for general linear asymmetric rotor systems. The methods are outlined and then applied to a typical rotor system represented by a 52 degree-or-freedom finite element model. The accuracy of the two methods is compared for this model and the complex model method is found to be

G. W. Fan; H. D. Nelson; P. E. Crouch; M. P. Mignolet

1993-01-01

201

Decentralized control of time-delayed uncertain symmetric composite systems  

Microsoft Academic Search

Reduced-order control design for a class of time–delayed uncertain nonlinear but nominally linear systems composed of identical nominal subsystems and symmetric interconnections is presented. Symmetric composite systems with time–delays and bounded parametric uncertainties both in subsystems and interconnections system matrices are considered for decentralized output control design using a controller–observer scheme. Luenberger–like delay–less observer is considered. First, an artificial reduced-order

L. Bakule

2003-01-01

202

Generalized symmetric extension for size-limited multirate filter banks  

Microsoft Academic Search

A multirate (MR) filter bank is called size-limited if the total number of output samples equals the number of input samples. A method called symmetric extension improved performance in subband image compression systems compared to the earlier method of circular convolution. However, the symmetric extension method was developed only for two-band uniform filter banks, and required even-length linear phase analysis

Roberto H. Bamberger; Steven L. Eddins; Veyis Nuri

1994-01-01

203

Convexity and symmetrization in relativistic theories  

NASA Astrophysics Data System (ADS)

There is a strong motivation for the desire to have symmetric hyperbolic field equations in thermodynamics, because they guarantee well-posedness of Cauchy problems. A generic quasi-linear first order system of balance laws — in the non-relativistic case — can be shown to be symmetric hyperbolic, if the entropy density is concave with respect to the variables. In relativistic thermodynamics this is not so. This paper shows that there exists a scalar quantity in relativistic thermodynamics whose concavity guarantees a symmetric hyperbolic system. But that quantity — we call it —bar h — is not the entropy, although it is closely related to it. It is formed by contracting the entropy flux vector — ha with a privileged time-like congruencebar ? _? . It is also shown that the convexity of h plus the requirement that all speeds be smaller than the speed of light c provide symmetric hyperbolic field equations for all choices of the direction of time. At this level of generality the physical meaning of —h is unknown. However, in many circumstances it is equal to the entropy. This is so, of course, in the non-relativistic limit but also in the non-dissipative relativistic fluid and even in relativistic extended thermodynamics for a non-degenerate gas.

Ruggeri, T.

1990-09-01

204

Optical realization of optimal symmetric real state quantum cloning machine  

NASA Astrophysics Data System (ADS)

We present an experimentally uniform linear optical scheme to implement the optimal 1?2 symmetric and optimal 1?3 symmetric economical real state quantum cloning machine of the polarization state of the single photon. This scheme requires single-photon sources and two-photon polarization entangled state as input states. It also involves linear optical elements and three-photon coincidence. Then we consider the realistic realization of the scheme by using the parametric down-conversion as photon resources. It is shown that under certain condition, the scheme is feasible by current experimental technology.

Hu, Gui-Yu; Zhang, Wen-Hai; Ye, Liu

2010-01-01

205

Combined topographic, spectroscopic, and model analyses of inhomogeneous energetic coupling of linear light harvesting complex II aggregates in native photosynthetic membranes.  

PubMed

Light harvesting by LH1 and LH2 antenna proteins in the photosynthetic membranes of purple bacteria has been extensively studied in recent years for the fundamental understanding of the energy transfer dynamics and mechanism. Here we report the inhomogeneous structural organization of the LH2 complexes in photosynthetic membranes, giving evidence for the existence of energetically coupled linear LH2 aggregates in the native photosynthetic membranes of purple bacteria. Focusing on systematic model analyses, we combined AFM imaging and spectroscopic analysis with energetic coupling model analysis to characterize the inhomogeneous linear aggregation of LH2. Our AFM imaging results reveal that the LH2 complexes form linear aggregates with the monomer number varying from one to eight and each monomer tilted along the aggregated structure in photosynthetic membranes. The spectroscopic results support the attribution of aggregated LH2 complexes in the photosynthetic membranes, and the model calculation values for the absorption, emission and lifetime are consistent with the experimentally determined spectroscopic values, further proving a molecular-level understanding of the energetic coupling and energy transfer among the LH2 complexes in the photosynthetic membranes. PMID:23474628

Rajapaksha, Suneth P; He, Yufan; Lu, H Peter

2013-04-21

206

An introduction to methods of complex analysis and geometry for classical mechanics and non-linear waves  

NASA Astrophysics Data System (ADS)

Contents: 1. Dealing with the singularities of analytic functions. 2. Singularities of differential equations and integrability. 3. Non-linear partial differential equations. 4. Painlevé transcendents in the theory of random matrices. 5. Symplectic geometry and physics: three introductory lectures.

Benest, Daniel; Froeschlé, Claude

207

Complex dynamics of isotropic 4-cyano-4-n-pentylbiphenyl (5CB) in linear and nonlinear dielectric relaxation studies  

Microsoft Academic Search

A comprehensive presentation of the temperature evolution of ``linear'' and ``nonlinear'' dielectric relaxation in the isotropic phase of nematic liquid crystalline compound 5CB (4-cyano-4-n-pentylbiphenyl) is given. The ``nonlinear'' relaxation is related to the strong pretransitional rise in the lifetime of prenematic fluctuations. The ``linear'' relaxation has a clear non-Debye and non-Arrhenius form. In the immediate vicinity of the nematic clearing

A. Drozd-Rzoska; S. J. Rzoska

2002-01-01

208

Solitons in PT-symmetric potential with competing nonlinearity  

NASA Astrophysics Data System (ADS)

We investigate the effect of competing nonlinearities on beam dynamics in PT-symmetric potentials. In particular, we consider the stationary nonlinear Schrödinger equation (NLSE) in one dimension with competing cubic and generalized nonlinearity in the presence of a PT-symmetric potential. Closed form solutions for localized states are obtained. These solitons are shown to be stable over a wide range of potential parameters. The transverse power flow associated with these complex solitons is also examined.

Khare, Avinash; Al-Marzoug, S. M.; Bahlouli, Hocine

2012-10-01

209

Thermal buckling of symmetrically laminated composite plates  

NASA Astrophysics Data System (ADS)

This paper discusses an investigation into the thermal buckling of symmetrically laminated composite plates. In this study thermal buckling is investigated for laminates under two different simple support conditions, fixed and sliding. These laminates are subjected to the conditions of a uniform temperature change, and a temperature change varying linearly along the length of the plate. The effects of the principal material axes not being aligned with the edges of the plate are also investigated. The buckling response is studied using variational methods, specifically the Trefftz criterion. A Rayleigh-Ritz formulation is used to obtain numerical results from the formulations for the prebuckling response and the buckling response.

Meyers, C. A.; Hyer, M. W.

210

DS\\/CDMA linear receiver based on Krylov-proportionate adaptive filtering technique—an extension to complex-valued signals  

Microsoft Academic Search

This paper presents a novel training-based adaptive linear receiver to suppress the multiple access interference, which has been one of the central issues in DS\\/CDMA wireless communication systems. The proposed receiver is derived by extending the Krylov-proportionate normalized least-mean-square (KPNLMS) algorithm to complex-valued signals. The key idea of KPNLMS is (a) sparse representation of the minimum mean square error (MMSE)

Masahiro Yukawa

2008-01-01

211

An iteration method for the symmetric solutions and the optimal approximation solution of the matrix equation AXB=C  

Microsoft Academic Search

An iteration method is constructed to solve the linear matrix equation AXB=C over symmetric X. By this iteration method, the solvability of the equation AXB=C over symmetric X can be determined automatically, when the equation AXB=C is consistent over symmetric X, its solution can be obtained within finite iteration steps, and its least-norm symmetric solution can be obtained by choosing

Ya-xin Peng; Xi-yan Hu; Lei Zhang

2005-01-01

212

Chirally symmetric but confining dense, cold matter  

SciTech Connect

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

Glozman, L. Ya.; Wagenbrunn, R. F. [Institute for Physics, Theoretical Physics Branch, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria)

2008-03-01

213

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

214

Dynamical behavior of a class of vibratory systems with symmetrical rigid stops near the point of codimension two bifurcation  

NASA Astrophysics Data System (ADS)

A multi-degree-of-freedom vibratory system having symmetrically placed rigid stops is considered. The system consists of linear components, but the maximum displacement of one of the masses is limited to a threshold value by the symmetrical rigid stops. Repeated impacts usually occur in the vibratory system due to the rigid amplitude constraints. Such models play an important role in the studies of mechanical systems with clearances or gaps. Local codimension two bifurcation of maps, involving a real eigenvalue and a complex conjugate pair escaping the unit circle simultaneously, is analyzed by using the center manifold theorem technique and normal form method for maps. Symmetrical double-impact periodic motion and Poincaré map of the system are derived analytically. A center manifold theorem technique is applied to reduce the Poincaré map to a three-dimensional one, and the normal form map associated with the codimension two bifurcation is obtained. Local behaviors of the vibratory systems with symmetrical rigid stops, near the points of codimension two bifurcations, are reported by the presentation of results for a two-degree-of-freedom vibratory system with symmetrical stops. The existence and stability of symmetrical double-impact periodic motion are analyzed explicitly. Also, local bifurcations at the points of change in stability, are analyzed. Near the point of codimension two bifurcation, there exists not only Hopf bifurcation of period-one double-impact motion, but also pitchfork bifurcation of the motion. Pitchfork bifurcation of period-one double-impact symmetrical motion results in the period-one double-impact unsymmetrical motion. The unsymmetrical double-impact motion is of two antisymmetrical forms due to different initial conditions and symmetrical stops. With change of the forcing frequency, the unsymmetrical double-impact periodic motion will undergo Hopf bifurcation. Moreover the period-one double-impact symmetrical motion will undergo Hopf bifurcation directly as the forcing frequency is changed in the contrary direction. The routes of quasi-periodic impact motions to chaos are observed by results from simulation.

Luo, G. W.; Zhang, Y. L.; Zhang, J. G.

2006-10-01

215

Study on complexity and non-linear of logistics finance management of supply chain system based on system dynamics  

Microsoft Academic Search

The structure of logistics financial management of supply chain system is an open system with complexity. The effectiveness of logisticspsila financial management of supply chain system is a nonlinear integration of fractal structurepsilas financial performance. The logistics financial management of supply chain system is a complex system of management and control. Its management areas have transcended the enterprisespsila borders, established

Yang Wang; Yu-lian Peng; Yuan-jing Luo

2008-01-01

216

Nonlinear Modes in Finite-Dimensional PT-Symmetric Systems  

NASA Astrophysics Data System (ADS)

By rearrangements of waveguide arrays with gain and losses one can simulate transformations among parity-time (PT-) symmetric systems not affecting their pure real linear spectra. Subject to such transformations, however, the nonlinear properties of the systems undergo significant changes. On an example of an array of four waveguides described by the discrete nonlinear Schrödinger equation with dissipation and gain, we show that the equivalence of the underlying linear spectra does not imply similarity of the structure or stability of the nonlinear modes in the arrays. Even the existence of one-parametric families of nonlinear modes is not guaranteed by the PT symmetry of a newly obtained system. In addition, the stability is not directly related to the PT symmetry: stable nonlinear modes exist even when the spectrum of the linear array is not purely real. We use a graph representation of PT-symmetric networks allowing for a simple illustration of linearly equivalent networks and indicating their possible experimental design.

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

2012-05-01

217

Interpreting Complex Binding Kinetics from Optical Biosensors: A Comparison of Analysis by Linearization, the Integrated Rate Equation, and Numerical Integration  

Microsoft Academic Search

The binding kinetics recorded for many interactions using BIAcore and IAsys optical biosensors do not fit a simple bimolecular interaction model (A + B ? AB). Three methods of analysis have been used to derive estimates for kinetic constants from such data: linearization, curve fitting using the integrated rate equation, and curve fitting using numerical integration. To test how well

T. A. Morton; D. G. Myszka; I. M. Chaiken

1995-01-01

218

O(Square root of n) Complexity Reduction for the Long-Step Path-Following Algorithm for Linear Programming.  

National Technical Information Service (NTIS)

The authors present a modification of a previously published long-step path-following algorithm for the solution of the linear programming problem. Our modification uses the simple Goldstein-Armijo rule, which enables us to show that an O(Sq rt(n) reducti...

D. den Hertog C. Roos J. P. Vial

1989-01-01

219

Averaging in spherically symmetric cosmology  

SciTech Connect

The averaging problem in cosmology is of fundamental importance. When applied to study cosmological evolution, the theory of macroscopic gravity (MG) can be regarded as a long-distance modification of general relativity. In the MG approach to the averaging problem in cosmology, the Einstein field equations on cosmological scales are modified by appropriate gravitational correlation terms. We study the averaging problem within the class of spherically symmetric cosmological models. That is, we shall take the microscopic equations and effect the averaging procedure to determine the precise form of the correlation tensor in this case. In particular, by working in volume-preserving coordinates, we calculate the form of the correlation tensor under some reasonable assumptions on the form for the inhomogeneous gravitational field and matter distribution. We find that the correlation tensor in a Friedmann-Lemaitre-Robertson-Walker (FLRW) background must be of the form of a spatial curvature. Inhomogeneities and spatial averaging, through this spatial curvature correction term, can have a very significant dynamical effect on the dynamics of the Universe and cosmological observations; in particular, we discuss whether spatial averaging might lead to a more conservative explanation of the observed acceleration of the Universe (without the introduction of exotic dark matter fields). We also find that the correlation tensor for a non-FLRW background can be interpreted as the sum of a spatial curvature and an anisotropic fluid. This may lead to interesting effects of averaging on astrophysical scales. We also discuss the results of averaging an inhomogeneous Lemaitre-Tolman-Bondi solution as well as calculations of linear perturbations (that is, the backreaction) in an FLRW background, which support the main conclusions of the analysis.

Coley, A. A.; Pelavas, N. [Department of Mathematics and Statistics, Dalhousie University, Halifax, Nova Scotia (Canada)

2007-02-15

220

Characterization of Mn(III) complexes of linear and cyclic desferrioxamines as mimics of superoxide dismutase activity.  

PubMed

The green complex of Mn(III) with desferrioxamine B has been prepared by air oxidation of Mn(II) in the presence of the ligand or by reaction of Mn(OH)3, or of MnO2, with the ligand. The resultant complex was purified by ion-exchange chromatography and shown by electrospray ionization mass spectrometry to be a 1:1 complex of Mn(III) with desferrioxamine B. A similar complex was prepared from the macrocyclic Tris hydroxamate desferrioxamine E. Mn(III) desferrioxamine B was not stable to equimolar EDTA while the Mn(III) desferrioxamine E was stable to a fivefold molar excess of EDTA. Chelex-100 decomposed the desferrioxamine B complex, but not the desferrioxamine E complex. These complexes prevented the reduction of cytochrome c by O2- but were less active than free Mn(II). The second-order rate constants for reaction with O2- at 25 degrees C and at pH 7.5 were 3.0 x 10(6), 1.0 x 10(6), and 9.5 x 10(4) for Mn(II), Mn(III) desferrioxamine B, and Mn(III) desferrioxamine E, respectively. PMID:8179317

Faulkner, K M; Stevens, R D; Fridovich, I

1994-05-01

221

Backbone dynamics of a symmetric calmodulin dimer in complex with the calmodulin-binding domain of the basic-helix-loop-helix transcription factor SEF2-1/E2-2: a highly dynamic complex.  

PubMed

Calmodulin (CaM) interacts specifically as a dimer with some dimeric basic-Helix-Loop-Helix (bHLH) transcription factors via a novel high affinity binding mode. Here we report a study of the backbone dynamics by (15)N-spin relaxation on the CaM dimer in complex with a dimeric peptide that mimics the CaM binding region of the bHLH transcription factor SEF2-1. The relaxation data were measured at multiple magnetic fields, and analyzed in a model-free manner using in-house written software designed to detect nanosecond internal motion. Besides picosecond motions, all residues also experience internal motion with an effective correlation time of approximately 2.5 ns with squared order parameter (S(2)) of approximately 0.75. Hydrodynamic calculations suggest that this can be attributed to motions of the N- and C-terminal domains of the CaM dimer in the complex. Moreover, residues with significant exchange broadening are found. They are clustered in the CaM:SEF2-1mp binding interface, the CaM:CaM dimer interface, and in the flexible helix connecting the CaM N- and C-terminal domains, and have similar exchange times (approximately 50 micros), suggesting a cooperative mechanism probably caused by protein:protein interactions. The dynamic features presented here support the conclusion that the conformationally heterogeneous bHLH mimicking peptide trapped inside the CaM dimer exchanges between different binding sites on both nanosecond and microsecond timescales. Nature has thus found a way to specifically recognize a relatively ill-fitting target. This novel mode of target-specific binding, which neither belongs to lock-and-key nor induced-fit binding, is characterized by dimerization and continuous exchange between multiple flexible binding alternatives. PMID:15894636

Larsson, Göran; Schleucher, Jürgen; Onions, Jacqueline; Hermann, Stefan; Grundström, Thomas; Wijmenga, Sybren S

2005-05-13

222

Backbone Dynamics of a Symmetric Calmodulin Dimer in Complex with the Calmodulin-Binding Domain of the Basic-Helix-Loop-Helix Transcription Factor SEF2-1/E2-2: A Highly Dynamic Complex  

PubMed Central

Calmodulin (CaM) interacts specifically as a dimer with some dimeric basic-Helix-Loop-Helix (bHLH) transcription factors via a novel high affinity binding mode. Here we report a study of the backbone dynamics by 15N-spin relaxation on the CaM dimer in complex with a dimeric peptide that mimics the CaM binding region of the bHLH transcription factor SEF2-1. The relaxation data were measured at multiple magnetic fields, and analyzed in a model-free manner using in-house written software designed to detect nanosecond internal motion. Besides picosecond motions, all residues also experience internal motion with an effective correlation time of ?2.5 ns with squared order parameter (S2) of ?0.75. Hydrodynamic calculations suggest that this can be attributed to motions of the N- and C-terminal domains of the CaM dimer in the complex. Moreover, residues with significant exchange broadening are found. They are clustered in the CaM:SEF2-1mp binding interface, the CaM:CaM dimer interface, and in the flexible helix connecting the CaM N- and C-terminal domains, and have similar exchange times (?50 ?s), suggesting a cooperative mechanism probably caused by protein:protein interactions. The dynamic features presented here support the conclusion that the conformationally heterogeneous bHLH mimicking peptide trapped inside the CaM dimer exchanges between different binding sites on both nanosecond and microsecond timescales. Nature has thus found a way to specifically recognize a relatively ill-fitting target. This novel mode of target-specific binding, which neither belongs to lock-and-key nor induced-fit binding, is characterized by dimerization and continuous exchange between multiple flexible binding alternatives.

Larsson, Goran; Schleucher, Jurgen; Onions, Jacqueline; Hermann, Stefan; Grundstrom, Thomas; Wijmenga, Sybren S.

2005-01-01

223

Principal Geodesic Analysis on Symmetric Spaces: Statistics of Diffusion Tensors  

Microsoft Academic Search

Diffusion tensor magnetic resonance imaging (DT-MRI) is emerging as an important tool in medical image analysis of the brain. However, relatively little work has been done on producing statistics of diffusion tensors. A main dif- ficulty is that the space of diffusion tensors, i.e., the space of symmetric, positive- definite matrices, does not form a vector space. Therefore, standard linear

P. Thomas Fletcher; Sarang C. Joshi

2004-01-01

224

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

225

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

226

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

Microsoft Academic Search

The analysis presented below suggests that the following equation models monodentate binding to negatively-charged oxygen donor atoms with no distinction between phenolic, carboxylic or inorganic hydroxide functional groups: logKML=?O logKHL+?O; where KML is the metal–ligand formation constant, KHL is the corresponding proton–ligand formation constant, and ?O and ?O are termed the Irving–Rossotti slope and intercept, respectively. Linear free energy relationships

Richard F. Carbonaro; Dominic M. Di Toro

2007-01-01

227

Imaging with tilted surfaces: an efficient matrix method for the generalized Scheimpflug condition and its application to rotationally symmetric triangulation  

NASA Astrophysics Data System (ADS)

An efficient two-dimensional matrix method is presented that facilitates the design of optical systems with tilted surfaces for which the requirement or knowledge of the orientation of the image plane is necessary, i.e., for which a generalized Scheimpflug condition is needed. In more general terms, the method results in imaging properties of second-order expansion, but the method is linear. Therefore the complexity of the design process is considerably reduced. The strength of the design method is demonstrated in detail for a novel application in which a reflective optical system of several surfaces is required for rotationally symmetric triangulation.

Ott, Peter

2005-06-01

228

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

2008-02-08

229

Progressive symmetrical erythrokeratodermia -- case report*.  

PubMed

Progressive symmetrical erythrokeratodermia is a rare autosomal dominant genodermatosis with variable penetrance described by Darier in 1911. It is characterized by erythematous and keratotic plaques, sharply defined and symmetrically distributed along the extremities, buttocks and, more rarely, on the face. We report a case of a 55-year-old patient with lesions on the dorsum of the hands, interphalangeal pads, wrists, groin and back feet. This case demonstrates a rare and late diagnosis, clinical profusion and presence of familiar involvement. PMID:23539014

Guaraldi, Bianca de Mello; Jaime, Thaís Jerez; Guaraldi, Rafael de Mello; Melo, Daniel Fernandes; Nogueira, Osvania Maris; Rodrigues, Nilton

230

Thin-shell wormholes: Linearization stability  

SciTech Connect

The class of spherically symmetric thin-shell wormholes provides a particularly elegant collection of exemplars for the study of traversable Lorentzian wormholes. In the present paper we consider linearized (spherically symmetric) perturbations around some assumed static solution of the Einstein field equations. This permits us to relate stability issues to the (linearized) equation of state of the exotic matter which is located at the wormhole throat. {copyright} 1995 The American Physical Society.

Poisson, E.; Visser, M. [Physics Department, Washington University, St. Louis, Missouri 63130-4899 (United States)

1995-12-15

231

PT-symmetric deformations of integrable models.  

PubMed

We review recent results on new physical models constructed as PT-symmetrical deformations or extensions of different types of integrable models. We present non-Hermitian versions of quantum spin chains, multi-particle systems of Calogero-Moser-Sutherland type and nonlinear integrable field equations of Korteweg-de Vries type. The quantum spin chain discussed is related to the first example in the series of the non-unitary models of minimal conformal field theories. For the Calogero-Moser-Sutherland models, we provide three alternative deformations: a complex extension for models related to all types of Coxeter/Weyl groups; models describing the evolution of poles in constrained real-valued field equations of nonlinear integrable systems; and genuine deformations based on antilinearly invariant deformed root systems. Deformations of complex nonlinear integrable field equations of Korteweg-de Vries type are studied with regard to different kinds of PT-symmetrical scenarios. A reduction to simple complex quantum mechanical models currently under discussion is presented. PMID:23509376

Fring, Andreas

2013-03-18

232

The structure of a polyQ-anti-polyQ complex reveals binding according to a linear lattice model.  

PubMed

Huntington and related neurological diseases result from expansion of a polyglutamine (polyQ) tract. The linear lattice model for the structure and binding properties of polyQ proposes that both expanded and normal polyQ tracts in the preaggregation state are random-coil structures but that an expanded polyQ repeat contains a larger number of epitopes recognized by antibodies or other proteins. The crystal structure of polyQ bound to MW1, an antibody against polyQ, reveals that polyQ adopts an extended, coil-like structure. Consistent with the linear lattice model, multimeric MW1 Fvs bind more tightly to longer than to shorter polyQ tracts and, compared with monomeric Fv, bind expanded polyQ repeats with higher apparent affinities. These results suggest a mechanism for the toxicity of expanded polyQ and a strategy to link anti-polyQ compounds to create high-avidity therapeutics. PMID:17450152

Li, Pingwei; Huey-Tubman, Kathryn E; Gao, Tiyu; Li, Xiaojun; West, Anthony P; Bennett, Melanie J; Bjorkman, Pamela J

2007-04-22

233

On the water dispersibility of a 1:1 stoichiometric complex between a cationic nanogel and linear polyanion.  

PubMed

This work aimed to obtain information on the water dispersibility of a 1:1 stoichiometric polyelectrolyte nanogel complex (SPENC). We synthesized a cationic polyelectrolyte nanogel (CPENG) composed of a cross-linked copolymer of 1-vinylimidazole and N-isopropylacrylamide. SPENC was then prepared at 25 degrees C from the mixing of equimolar amounts (based on fixed charges) of CPENG and potassium poly(vinyl alcohol) sulfate, which were dissolved in an aqueous solution without adding salt and at pH 3.0. We carefully observed at 25 degrees C the reduction of the imidazole-based cationic charge in the CPENG component of SPENC as a function of pH. Dynamic and static light scattering techniques were employed in combination with electrophoretic light scattering experiments. The amount of cationic charge in the SPENC was estimated from the potentiometric titration data of CPENG. It was found that, during the charge reduction process, the complex underwent aggregation, followed by a phase separation. The aggregation started at about 25% of the charge reduction (i.e., at pH approximately = 4.9), and the phase separation took place when almost half of the charge was eliminated (at pH approximately = 5.5). However, the phase-separated complexes became water-soluble again when about 90% of the charge was eliminated (pH approximately = 6.6). By colloid titration, the dissociated free polyanions were not detected in the aqueous SPENC solution before the phase separation but were detected in the complex-redispersed solution. When the pH (9.0) of the redispersion was slowly decreased to the original level (pH 3.0) by the gradual addition of HCl so as to cause again the phase separation, an intraparticle complex was reformed, the physical quantities of which were close to those of the initial SPENC. These findings clearly indicate that the whole and a part (segment) of the complexed polyanions undergoes dissociation-association reactions on the surface of a SPENC particle, depending on the ionization state of the cationic gel component. As a result, these reactions seem to be a key factor for the water dispersibility of the SPENC. PMID:20695607

Doi, Ryo; Kokufuta, Etsuo

2010-08-17

234

The role of 'hidden preferences' in the artificial co-evolution of symmetrical signals  

PubMed Central

Recently, within the biology literature, there has been some interest in exploring the evolutionary function of animal displays through computer simulations of evolutionary processes. Here we provide a critique of an exploration of the evolutionary function of complex symmetrical displays. We investigate the hypothesis that complex symmetrical signal form is the product of a 'hidden preference' inherent in all sensory systems (i.e. a universal sensory bias). Through extending previous work and relaxing its assumptions we reveal that the posited 'hidden preference' for complex symmetry is in reality a preference for homogeneity. The resulting implications for further accounts of the evolutionary function of complex symmetrical patterning are considered.

Bullock, S.; Cliff, D.

1997-01-01

235

Generalized linear mixed models for ordered responses in complex multilevel structures: effects beneath the school or college in education  

Microsoft Academic Search

The complexities of educational processes and structure and the need for disentangling effects beneath the level of the school or college are discussed. Ordinal response multilevel crossed random-effects models for educational grades are introduced. Weighted random effects for teacher contributions are then added. Estimation methodology is reviewed. Specially written macros for quasi-likelihood with second-order terms are described. The application discusses

Antony Fielding; Min Yang

2005-01-01

236

Mesomorphous structure change by tail chain number in ionic liquid crystalline complexes of linear polymer and amphiphiles  

Microsoft Academic Search

Three polymer–amphiphile complexes were prepared by combining poly(allylamine hydrochloride) (PAH) with the potassium salt of mono-, di-, and trisubstituted benzoic acid dendrons (4-octyloxybenzoic acid, 3,5-dioctyloxybenzoic acid, and 3,4,5-trioctyloxybenzoic acid). The solid structure and properties were monitored with FT-IR, XRD, TG, DSC, and polarized optical microscope (POM). Difference in the tail chain number of the dendritic amphiphile induced two different mesomorphous

Zhi Yu Cheng; Bi Ye Ren; Shu Ying He; Xin Xing Liu; Zhen Tong

2011-01-01

237

Is Symmetrical Communication Ethical and Effective?  

Microsoft Academic Search

The purpose of this paper is to explore two questions:(1) Is symmetrical communication in public relations practice inherently ethical?(2) Does symmetrical communication contribute to public relations effectiveness and organizational effectiveness? Three surveys are undertaken to test seven research hypotheses for the purpose of cross-validating research findings. The results suggest that symmetrical communication is inherently ethical. Moreover, symmetrical communication indeed contributes

Yi-Hui Huang

2004-01-01

238

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.

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

2012-01-01

239

APPROXIMATING SYMMETRIC POSITIVE SEMIDEFINITE TENSORS OF EVEN ORDER().  

PubMed

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 [Formula: see text] of 2m(th)-order symmetric positive semi-definite tensors is known to be a convex cone, enforcing positivity constraint directly on [Formula: see text] is usually not straightforward computationally because there is no known analytic description of [Formula: see text] for m > 1. In this paper, we propose a novel approach for enforcing the positivity constraint on even-order tensors by approximating the cone [Formula: see text] for the cases 0 < m < 3, and presenting an explicit characterization of the approximation ?(2) (m) ? ?(2) (m) for m ? 1, using the subset [Formula: see text] 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 ?(2) (m). Finally, we experimentally validate the proposed approach and we present an application for computing 2m(th)-order diffusion tensors from Diffusion Weighted Magnetic Resonance Images. PMID:23285313

Barmpoutis, Angelos; Jeffrey, Ho; Vemuri, Baba C

2012-03-20

240

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

241

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

PubMed Central

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

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

2011-01-01

242

Stability of spherically symmetric solutions in modified theories of gravity  

NASA Astrophysics Data System (ADS)

In recent years, a number of alternative theories of gravity have been proposed as possible resolutions of certain cosmological problems or as toy models for possible but heretofore unobserved effects. However, the implications of such theories for the stability structures such as stars have not been fully investigated. We use our "generalized variational principle", described in a previous work, to analyze the stability of static spherically symmetric solutions to spherically symmetric perturbations in three such alternative theories: Carroll et al.'s f(R) gravity, Jacobson & Mattingly's "Einstein-aether theory", and Bekenstein's TeVeS. We find that in the presence of matter, f(R) gravity is highly unstable; that the stability conditions for spherically symmetric curved vacuum Einstein-aether backgrounds are the same as those for linearized stability about flat spacetime, with one exceptional case; and that the "kinetic terms" of vacuum TeVeS are indefinite in a curved background, leading to an instability.

Seifert, Michael D.

243

Plane symmetric thin-shell wormholes: Solutions and stability  

SciTech Connect

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

Lemos, Jose P. S.; Lobo, Francisco S. N. [Centro Multidisciplinar de Astrofisica-CENTRA, Departamento de Fisica, Instituto Superior Tecnico-IST, Universidade Tecnica de Lisboa-UTL, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Institute of Gravitation and Cosmology, University of Portsmouth, Portsmouth PO1 2EG, United Kingdom and Centro de Astronomia e Astrofisica da Universidade de Lisboa, Campo Grande, Edificio C8, 1749-016 Lisboa (Portugal)

2008-08-15

244

Rotationally symmetric operators for surface interpolation  

SciTech Connect

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

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

1982-01-01

245

Looking for symmetric Bell inequalities  

NASA Astrophysics Data System (ADS)

Finding all Bell inequalities for a given number of parties, measurement settings and measurement outcomes is in general a computationally hard task. We show that all Bell inequalities which are symmetric under the exchange of parties can be found by examining a symmetrized polytope which is simpler than the full Bell polytope. As an illustration of our method, we generate 238 885 new Bell inequalities and 1085 new Svetlichny inequalities. We find, in particular, facet inequalities for Bell experiments involving two parties and two measurement settings that are not of the Collins-Gisin-Linden-Massar-Popescu type.

Bancal, Jean-Daniel; Gisin, Nicolas; Pironio, Stefano

2010-09-01

246

Linear and nonlinear two-coordinate vanadium complexes: synthesis, characterization, and magnetic properties of V(II) amides.  

PubMed

The synthesis and characterization of the first stable two-coordinate vanadium complexes are described. The vanadium(II) primary amido derivative V{N(H)Ar(iPr6)}2 [Ar(iPr6) = C6H3-2,6-(C6H2-2,4,6-iPr3)2] (1) was synthesized via the reaction of LiN(H)Ar(iPr6) with the V(III) complex VCl3·2NMe3 or the V(II) salt [V2Cl3(THF)6](+)I(-) in a 2:1 and 4:1 stoichiometry, respectively. Reaction of the less crowded LiN(H)Ar(Me6) with [V2Cl3(THF)6](+)I(-) afforded V{N(H)Ar(Me6)}2 [Ar(Me6) = C6H3-2,6-(C6H2-2,4,6-Me3)2] (2), which has a nonlinear [N-V-N = 123.47(9)°] vanadium coordination. Magnetometry studies showed that V{N(H)Ar(iPr6)}2 and V{N(H)Ar(Me6)}2 have ambient temperature magnetic moments of 3.41 and 2.77 ?B, respectively, which are consistent with a high-spin d(3) electron configuration. These values suggest a significant spin orbital angular momentum contribution that leads to a magnetic moment that is lower than their spin-only value of 3.87 ?B. DFT calculations showed that the major absorptions in their UV-vis spectra were due to ligand to metal charge transfer transitions. Exposure of the reaction mixture for 2 to dry O2 resulted in the formation of the diamagnetic V(V) oxocluster [V{N(H)Ar(Me6)}2]2(?-O-Li-O)2 (3). PMID:23782062

Boynton, Jessica N; Guo, Jing-Dong; Fettinger, James C; Melton, Christopher E; Nagase, Shigeru; Power, Philip P

2013-07-10

247

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.

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

2011-01-01

248

The topology of symmetric, second-order tensor fields  

Microsoft Academic Search

We study the topology of symmetric, second-order 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. We extract topological skeletons of the eigenvector fields, and we track their evolution over time. We study tensor topological transitions and correlate tensor and vector data.The basic constituents

Thierry Delmarcelle; Lambertus Hesselink

1994-01-01

249

Bis(arene) actinide sandwich complexes, ({eta}{sup 6}-C{sub 6}H{sub 3}R{sub 3}){sub 2}An: Linear or bent?  

SciTech Connect

The syntheses of the sandwich complexes ferrocene, ({eta}{sup 5}-C{sub 5}H{sub 5}){sub 2}-Fe, in 1951 and uranocene, ({eta}{sup 8}-C{sub 8}H{sub 8}){sub 2}U, in 1968 ushered in the modern eras of organotransition metal and organoactinide chemistry, respectively. Ferrocene and uranocene are examples of linear sandwich complexes, that is, those in which the (ring centroid)-M-(ring centroid) angle (denoted {theta}) is 180{degree}. In the case of ({eta}{sup 5}-C{sub 5}H{sub 5}){sub 2}M chemistry, a number of bent ({theta} < 180{degree}) complexes are known when M is a main-group or rare-earth element. The explanation for the bent structures of these complexes has been the subject of some debate concerning the relative importance of covalent, electrostatic, and steric interactions. The authors report optimized geometries of Bz{sub 2}An (An = Th-Am) and ({eta}{sup 6}-C{sub 6}H{sub 3}R{sub 3}){sub 2}An (An = Th, U, Pu; R = Me, {sup t}Bu) obtained by using local density approximation (LDA) and Perdew-Wang (PW91) gradient-corrected relativistic density functional theory (DFT) methods. These DFT methods are found to be able to reproduce the experimental geometries and vibrational frequencies of organoactinide complexes with satisfactory accuracy. The (TTB){sub 2}An calculations that are reported here are, to date, the largest full geometry optimizations to be carried out on an actinide system.

Li, J.; Bursten, B.E.

1999-11-03

250

A Symmetric Bipolar Nebula Around MWC 922  

NASA Astrophysics Data System (ADS)

We report regular and symmetric structure around dust-enshrouded Be star MWC 922 with infrared imaging. Biconical lobes that appear nearly square in aspect, forming this “Red Square” nebula, are crossed by a series of rungs that terminate in bright knots or “vortices,” while an equatorial dark band crossing the core delimits twin hyperbolic arcs. The intricate yet cleanly constructed forms that comprise the skeleton of the object argue for minimal perturbation from global turbulent or chaotic effects. We also report the presence of a linear comb structure, which may arise from optically projected shadows of a periodic feature in the inner regions, such as corrugations in the rim of a circumstellar disk. The sequence of nested polar rings draws comparison with the triple-ring system seen around the only naked-eye supernova in recent history: SN1987A.

Tuthill, P. G.; Lloyd, J. P.

2007-04-01

251

Canonical quantization of static spherically symmetric geometries  

NASA Astrophysics Data System (ADS)

The conditional symmetries of the reduced Einstein–Hilbert action emerging from a static, spherically symmetric geometry are used as supplementary conditions on the wave function. Based on their integrability conditions, only one of the three existing symmetries can be consistently imposed, while the unique Casimir invariant, being the product of the remaining two symmetries, is calculated as the only possible second condition on the wave function. This quadratic integral of motion is identified with the reparametrization generator, as an implication of the uniqueness of the dynamical evolution, by fixing a suitable parametrization of the r-lapse function. In this parametrization, the determinant of the supermetric plays the role of the mesure. The combined Wheeler – DeWitt and linear conditional symmetry equations are analytically solved. The solutions obtained depend on the product of the two "scale factors".

Christodoulakis, T.; Dimakis, N.; Terzis, P. A.; Doulis, G.; Grammenos, Th; Melas, E.; Spanou, A.

2013-08-01

252

Molecular Detection of Targeted Major Histocompatibility Complex I-Bound Peptides Using a Probabilistic Measure and Nanospray MS3 on a Hybrid Quadrupole-Linear Ion Trap  

PubMed Central

A nanospray MS3 method deployed on a quadrupole linear ion trap hybrid can detect targeted peptides with high dynamic range and high sensitivity from complex mixtures without separations. The method uses a recognition algorithm that is a modification of the relative (Kullback?Leibler, KL) entropy characterization of probabilistic distance to detect if reference MS3 fragmentation patterns are components of acquired MS3 spectra. The recognition reflects the probabilistic structure of physical MS measurements unlike the Euclidean or inner product metrics widely used for comparing spectra. It capably handles spectra with a significant chemical ion background in contrast to the Euclidean metric or the direct relative entropy. The full nanospray MS3 method allows both the detection and quantitation of targets without the need to obtain isotopically labeled standards. By avoiding chromatographic separations and its associated surface losses, the detection can be applied to complex samples on a very limited material scale. The methodology is illustrated by applications to the medically important problem of detecting targeted major histocompatibility complex (MHC) I associated peptides extracted from limited cell numbers.

2010-01-01

253

A note on symmetric connections  

NASA Astrophysics Data System (ADS)

In this paper we analyze a reciprocal of the fundamental theorem of Riemannian geometry. We give a condition for a symmetric connection to be locally the Levi-Civita connection of a metric. We also construct a couple of natural examples of connections on the n-dimensional torus and investigate the global problem.

Cocos, M.

2006-03-01

254

Shearfree Spherically Symmetric Fluid Models  

NASA Astrophysics Data System (ADS)

We attempt to discover some exact analytical models of the spherically symmetric spacetime of collapsing fluid under shearfree conditions. Two types of solution are considered: one is to impose a condition on the mass function, while the other is to restrict the pressure. We obtain five exact models in total, and some of them satisfy the Darmois conditions.

Sharif, M.; Yousaf, Z.

2012-05-01

255

Response matrix of symmetric nodes  

Microsoft Academic Search

Properties of a symmetric node's response matrix are discussed. The node may have an internal structure such that it remains invariant under the symmetry transformations of the considered node. A transformation diagonalizing the response matrix is given by means of symmetry considerations. The equivalence is demonstrated of the response matrix method to a finite difference scheme in which the dependent

Makai

1984-01-01

256

Characterisation of a symmetric AGATA detector using the ?-ray imaging scanning technique  

NASA Astrophysics Data System (ADS)

The imaging scanning technique for the characterisation of large volume, highly segmented, HPGe detectors is demonstrated by comparing the measured spatial response of a symmetric AGATA crystal versus the theoretical calculations obtained with the Multi-Geometry Simulation (MGS) code. The signal rise-times measured as a function of the gamma-ray interaction positions, in both coaxial and planar regions of the detection volume, are presented and confronted with the expected behaviour obtained via MGS. The transition in charge carrier transport behaviour as a function of the depth is studied for the region of the complex electric field. In general, a fairly good agreement between theory and experiment is obtained. Only systematic deviations between simulation and measurement are observed in the critical front part of the AGATA detector. They may be ascribed to a non-linear impurity concentration profile of the germanium crystal.

Goel, N.; Domingo-Pardo, C.; Habermann, T.; Ameil, F.; Engert, T.; Gerl, J.; Kojouharov, I.; Maruhn, J.; Pietralla, N.; Schaffner, H.

2013-02-01

257

Pyramid diffraction in parity-time-symmetric optical lattices.  

PubMed

Nonlinear dynamics of wave packets in two-dimensional parity-time-symmetric optical lattices near the phase transition point are analytically studied. A 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. PMID:23722794

Nixon, Sean; Yang, Jianke

2013-06-01

258

Solving Elliptic Finite Element Systems in Near-Linear Time with Support Preconditioners  

Microsoft Academic Search

We consider linear systems arising from the use of the finite element method for solving a certain class of linear elliptic problems. Our main result is that these linear systems, which are symmetric and positive semidefinite, are well approximated by symmetric diagonally dominant matrices. Our framework for defining matrix approximation is support theory. Significant graph theoretic work has already been

Erik G. Boman; Bruce Alan Hendrickson; Stephen A. Vavasis

2004-01-01

259

Linear correlations between sets of variables  

Microsoft Academic Search

While the traditional multiple correlation coefficient appears to be inherently an asymmetrical statistic, it is actually a special case of a more general measure of linear relationship between twosets of variables. Another symmetric generalization of linear correlation is to the total relatednesswithin a set of variables. Both of these developments rest upon thegeneralized variance of a multivariate distribution, which is

William W. Rozeboom

1965-01-01

260

Ordinary versus PT-symmetric ?3 quantum field theory  

NASA Astrophysics Data System (ADS)

A quantum-mechanical theory is PT-symmetric if it is described by a Hamiltonian that commutes with PT, where the operator P performs space reflection and the operator T performs time reversal. A PT-symmetric Hamiltonian often has a parametric region of unbroken PT symmetry in which the energy eigenvalues are all real. There may also be a region of broken PT symmetry in which some of the eigenvalues are complex. These regions are separated by a phase transition that has been repeatedly observed in laboratory experiments. This paper focuses on the properties of a PT-symmetric ig?3 quantum field theory. This quantum field theory is the analog of the PT-symmetric quantum-mechanical theory described by the Hamiltonian H=p2+ix3, whose eigenvalues have been rigorously shown to be all real. This paper compares the renormalization group properties of a conventional Hermitian g?3 quantum field theory with those of the PT-symmetric ig?3 quantum field theory. It is shown that while the conventional g?3 theory in d=6 dimensions is asymptotically free, the ig?3 theory is like a g?4 theory in d=4 dimensions; it is energetically stable, perturbatively renormalizable, and trivial.

Bender, Carl M.; Branchina, Vincenzo; Messina, Emanuele

2012-04-01

261

A Symmetric Triangle-Square Waveform Generator Using a Single Constant Current Source  

Microsoft Academic Search

A symmetric and accurate triangular waveform generating circuit is described. A simple approach in maintaining the symmetry and linearity of triangular waveform is made by using a single constant current generator to alternately charge and discharge a capacitor in a linear manner. This features perfect symmetry of the waveform over a wide frequency range while maintaining amplitude constancy. The circuit

Dipak K. Basu; Pradip K. Das

1972-01-01

262

Symmetric functions and P-recursiveness  

Microsoft Academic Search

Many enumeration problems, such as that of counting nonnegative integer matrices with given row and column sums, have solutions which can be expressed as coefficients of symmetric functions. We show here how useful formulas can be obtained from these symmetric function generating functions. In some cases, the symmetric functions yield reasonably simple explicit formulas or generating functions for the coefficients.

Ira M. Gessel

1990-01-01

263

Range Symmetric Matrices in Minkowski Space  

Microsoft Academic Search

The concept of range symmetric matrix is introduced in Minkowski space m. Equivalent conditions for a matrix to be range symmetric are determined. The existence of the Minkowski inverse of a range symmetric matrix in m is discussed. ? = n u u u u u L Let G be the Minkowski metric tensor defined by . ) , ,

A. R. MEENAKSHI

2000-01-01

264

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

265

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

266

Symmetrical Multifoil Shields for reducing Spray Drift  

Microsoft Academic Search

In this study, two symmetrical multi-foil shields were designed to minimise spray drift in both upwind and downwind travel directions. One shield was a symmetrical double foil that induced direct air assist (an air jet acting directly on the spray droplets), while the other shield was a symmetrical triple foil that induced both direct air assist and an air curtain

M. M Sidahmed; H. H Awadalla; M. A Haidar

2004-01-01

267

Symmetric informationally complete quantum measurements  

Microsoft Academic Search

We consider the existence in arbitrary finite dimensions d of a positive operator valued measure (POVM) comprised of d2 rank-one operators all of whose operator inner products are equal. Such a set is called a “symmetric, informationally complete” POVM (SIC–POVM) and is equivalent to a set of d2 equiangular lines in Cd. SIC–POVMs are relevant for quantum state tomography, quantum

Joseph M. Renes; Robin Blume-Kohout; A. J. Scott; Carlton M. Caves

2004-01-01

268

Symmetric Key Authentication Services Revisited  

Microsoft Academic Search

Most of the symmetric key authentication schemes deployed today are based on principles introduced by Needham and Schroeder (17) more than twenty years ago. However, since then, the computing environment has evolved from a LAN-based client-server world to include new paradigms, including wide area networks, peer-to-peer networks, mobile ad-hoc networks and ubiquitous computing. Also, there are new threats, including viruses,

Bruno Crispo; Bogdan C. Popescu; Andrew S. Tanenbaum

2004-01-01

269

Symmetric informationally complete quantum measurements  

Microsoft Academic Search

We consider the existence in arbitrary finite dimensions d of a positive operator valued measure (POVM) comprised of d2 rank-one operators all of whose operator inner products are equal. Such a set is called a ``symmetric, informationally complete'' POVM (SIC-POVM) and is equivalent to a set of d2 equiangular lines in Cd. SIC-POVMs are relevant for quantum state tomography, quantum

Joseph M. Renes; Robin Blume-Kohout; A. J. Scott; Carlton M. Caves

2004-01-01

270

Order-Preserving Symmetric Encryption  

Microsoft Academic Search

We initiate the cryptographic study of order-preserving symmetric encryption (OPE), a prim- itive suggested in the database community by Agrawal et al. (SIGMOD '04) for allowing ecient range queries on encrypted data. Interestingly, we rst show that a straightforward relaxation of standard security notions for encryption such as indistinguishability against chosen-plaintext attack (IND-CPA) is unachievable by a practical OPE scheme.

Alexandra Boldyreva; Nathan Chenette; Younho Lee; Adam O’Neill

2009-01-01

271

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

272

Modeling and analysis of the in-plane vibration of a complex cable-stayed bridge  

NASA Astrophysics Data System (ADS)

The in-plane vibration of a complex cable-stayed bridge that consists of a simply-supported four-cable-stayed deck beam and two rigid towers is studied. The nonlinear and linear partial differential equations that govern transverse and longitudinal vibrations of the cables and transverse vibrations of segments of the deck beam, respectively, are derived, along with their boundary and matching conditions. The undamped natural frequencies and mode shapes of the linearized model of the cable-stayed bridge are determined, and orthogonality relations of the mode shapes are established. Numerical analysis of the natural frequencies and mode shapes of the cable-stayed bridge is conducted for various symmetrical and non-symmetrical bridge cases with regards to the sizes of the components of the bridge and the initial sags of the cables. The results show that there are very close natural frequencies when the bridge model is symmetrical and/or partially symmetrical, and the mode shapes tend to be more localized when the bridge model is less symmetrical. The relationships between the natural frequencies and mode shapes of the cable-stayed bridge and those of a single fixed-fixed cable and the single simply-supported deck beam are analyzed. The results, which are validated by commercial finite element software, demonstrate some complex classical resonance behavior of the cable-stayed bridge.

Cao, D. Q.; Song, M. T.; Zhu, W. D.; Tucker, R. W.; Wang, C. H.-T.

2012-12-01

273

Analysis of bladder-outlet function with the linearized passive urethral resistance relation, linPURR, and a disease-specific approach for grading obstruction: from complex to simple  

Microsoft Academic Search

The concept of the passive urethral resistance relation (PURR) to quantify bladder outflow conditions in few parameters from the complex pressure\\/flow relation is generally accepted. The most simple, yet realistic, linearized format is the linear PURR (linPURR). This two-dimensional format allows clear identification of individual outflow conditions with distinction of different obstruction types. Unequivocal grading of obstruction, however, requires a

W. Schäfer

1995-01-01

274

Generic spherically symmetric dynamic thin-shell traversable wormholes in standard general relativity  

NASA Astrophysics Data System (ADS)

We consider the construction of generic spherically symmetric thin-shell traversable wormhole spacetimes in standard general relativity. By using the cut-and-paste procedure, we comprehensively analyze the stability of arbitrary spherically symmetric thin-shell wormholes to linearized spherically symmetric perturbations around static solutions. While a number of special cases have previously been dealt with in scattered parts of the literature, herein we take considerable effort to make the analysis as general and unified as practicable. We demonstrate in full generality that stability of the wormhole is equivalent to choosing suitable properties for the exotic material residing on the wormhole throat.

Garcia, Nadiezhda Montelongo; Lobo, Francisco S. N.; Visser, Matt

2012-08-01

275

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

276

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.

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

2011-01-01

277

On the characterization of dynamic supramolecular systems: a general mathematical association model for linear supramolecular copolymers and application on a complex two-component hydrogen-bonding system.  

PubMed

A general mathematical model for the characterization of the dynamic (kinetically labile) association of supramolecular assemblies in solution is presented. It is an extension of the equal K (EK) model by the stringent use of linear algebra to allow for the simultaneous presence of an unlimited number of different units in the resulting assemblies. It allows for the analysis of highly complex dynamic equilibrium systems in solution, including both supramolecular homo- and copolymers without the recourse to extensive approximations, in a field in which other analytical methods are difficult. The derived mathematical methodology makes it possible to analyze dynamic systems such as supramolecular copolymers regarding for instance the degree of polymerization, the distribution of a given monomer in different copolymers as well as its position in an aggregate. It is to date the only general means to characterize weak supramolecular systems. The model was fitted to NMR dilution titration data by using the program Matlab, and a detailed algorithm for the optimization of the different parameters has been developed. The methodology is applied to a case study, a hydrogen-bonded supramolecular system, salen 4+porphyrin 5. The system is formally a two-component system but in reality a three-component system. This results in a complex dynamic system in which all monomers are associated to each other by hydrogen bonding with different association constants, resulting in homo- and copolymers 4n5m as well as cyclic structures 6 and 7, in addition to free 4 and 5. The system was analyzed by extensive NMR dilution titrations at variable temperatures. All chemical shifts observed at different temperatures were used in the fitting to obtain the DeltaH degrees and DeltaS degrees values producing the best global fit. From the derived general mathematical expressions, system 4+5 could be characterized with respect to above-mentioned parameters. PMID:17868169

Odille, Fabrice G J; Jónsson, Stefán; Stjernqvist, Susann; Rydén, Tobias; Wärnmark, Kenneth

2007-01-01

278

Artificial Second Order Non-Linearity in Photonic Crystals.  

National Technical Information Service (NTIS)

We describe a technique for obtaining effective second order non- linearity X(sup 2) in non-centro-symmetric Photonic Crystal made from centro- symmetric materials (e.g., glass, Ge or Si). The effect is based on the electric quadrupole transition, strong ...

A. Feigel B. Sfez Z. Kotler

2002-01-01

279

Demixing in symmetric supersolid mixtures  

NASA Astrophysics Data System (ADS)

The droplet crystal phase of a symmetric binary mixture of soft-core bosons is studied by computer simulation. At high temperature each droplet comprises on average equal numbers of particles of either component, but the two components demix below the supersolid transition temperature, i.e., droplets mostly consist of particles of one component. Clustering of droplets of the same component is also observed. Demixing is driven by quantum tunneling of particles across droplets over the system and does not take place in an insulating crystal. This effect provides an unambiguous experimental signature of supersolidity.

Jain, Piyush; Moroni, Saverio; Boninsegni, Massimo; Pollet, Lode

2013-09-01

280

Conformally flat spherically symmetric spacetimes  

NASA Astrophysics Data System (ADS)

We deduce a simple expression for the Kretschmann curvature scalar of a conformally flat spacetime with a perfect fluid. Conformally flat, static, spherically symmetric spacetimes are investigated in various coordinate systems. The equation for a vanishing Weyl tensor and Einstein's field equations are integrated in curvature coordinates. We find conformally flat generalizations of the de Sitter spacetime and give new analyses of the internal Schwarzschild spacetime and texture-dominated spacetimes. The spacetimes are described in curvature coordinates, isotropic coordinates and in conformally flat spacetime coordinates.

Grøn, Øyvind; Johannesen, Steinar

2013-08-01

281

From particle in a box to PT -symmetric systems via isospectral deformation  

Microsoft Academic Search

A family of PT -symmetric complex potentials are obtained which is isospectral to free particle in an infinite complex box in one dimension (1-D). These are generalizations to the cosec2(x) potential, isospectral to particle in a real infinite box. In the complex plane, the infinite box is extended parallel to the real axis having a real width, which is found

Philip Cherian; Kumar Abhinav; P. K. Panigrahi

2011-01-01

282

PT-symmetric dimer of coupled nonlinear oscillators  

NASA Astrophysics Data System (ADS)

We provide a systematic analysis of a prototypical nonlinear oscillator system respecting PT symmetry i.e., one of them has gain and the other an equal and opposite amount of loss. Starting from the linear limit of the system, we extend considerations to the nonlinear case for both soft and hard cubic nonlinearities identifying symmetric and antisymmetric breather solutions, as well as symmetry-breaking variants thereof. We propose a reduction of the system to a Schrödinger-type PT-symmetric dimer, whose detailed earlier understanding can explain many of the phenomena observed herein, including the PT phase transition. Nevertheless, there are also significant parametric as well as phenomenological potential differences between the two models and we discuss where these arise and where they are most pronounced. Finally, we also provide examples of the evolution dynamics of the different states in their regimes of instability.

Cuevas, Jesús; Kevrekidis, Panayotis G.; Saxena, Avadh; Khare, Avinash

2013-09-01

283

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

284

Current simulation of symmetric contacts on CdTe  

NASA Astrophysics Data System (ADS)

This article presents the calculated current-voltage characteristics of symmetric Metal-Semiconductor-Metal configurations for Schottky, Ohmic, and injecting-Ohmic contacts on high resistivity CdTe. The results clearly demonstrate that in the wide band-gap, semi-insulating semiconductors, such as high resistivity CdTe, the linearity of the I - V curves cannot be considered a proof of the ohmicity of the contacts. It is shown that the linear I - V curves are expected for a wide range of contact barriers. Furthermore, the slope of these linear curves is governed by the barrier height, rather than the bulk doping concentration. Therefore the deduction of bulk's resistivity from the I - V curves may be false.

Ruzin, A.

2011-12-01

285

Symmetrical mixtures in external fields.  

PubMed

We have studied the behavior of symmetrical binary mixtures of Lennard-Jones particles in contact with strongly adsorbing walls using Monte Carlo simulation methods in the grand canonical and semi-grand canonical ensembles. Two types of the surface potential have been applied. The first depends on the distance from the surface only, while the second involves periodic modulations in the directions parallel to the wall. In the latter case, it has been assumed that the solid substrate is a fcc crystal with the surface being the (100) face. We have considered the systems in which the surface potential is strong enough to induce the layer-by-layer adsorption at low temperatures and discussed the interplay between the demixing transition and the structure of thin films for several systems characterized by different parameters describing the interactions in the system. PMID:23822318

Materniak, S; Patrykiejew, A

2013-07-01

286

A purely Lagrangian method for computing linearly-perturbed flows in spherical geometry  

NASA Astrophysics Data System (ADS)

In many physical applications, one wishes to control the development of multi-dimensional instabilities around a one-dimensional (1D) complex flow. For predicting the growth rates of these perturbations, a general numerical approach is viable which consists in solving simultaneously the one-dimensional equations and their linearized form for three-dimensional perturbations. In Clarisse et al. [J.-M. Clarisse, S. Jaouen, P.-A. Raviart, A Godunov-type method in Lagrangian coordinates for computing linearly-perturbed planar-symmetric flows of gas dynamics, J. Comp. Phys. 198 (2004) 80 105], a class of Godunov-type schemes for planar-symmetric flows of gas dynamics has been proposed. Pursuing this effort, we extend these results to spherically symmetric flows. A new method to derive the Lagrangian perturbation equations, based on the canonical form of systems of conservation laws with zero entropy flux [B. Després, Lagrangian systems of conservation laws. Invariance properties of Lagrangian systems of conservation laws, approximate Riemann solvers and the entropy condition, Numer. Math. 89 (2001) 99 134; B. Després, C. Mazeran, Lagrangian gas dynamics in two dimensions and Lagrangian systems, Arch. Rational Mech. Anal. 178 (2005) 327 372] is also described. It leads to many advantages. First of all, many physical problems we are interested in enter this formalism (gas dynamics, two-temperature plasma equations, ideal magnetohydrodynamics, etc.) whatever is the geometry. Secondly, a class of numerical entropic schemes is available for the basic flow [11]. Last, linearizing and devising numerical schemes for the perturbed flow is straightforward. The numerical capabilities of these methods are illustrated on three test cases of increasing difficulties and we show that due to its simplicity and its low computational cost the Linear Perturbations Code (LPC) is a powerful tool to understand and predict the development of hydrodynamic instabilities in the linear regime.

Jaouen, Stéphane

2007-07-01

287

Introduction to Linear Dynamical Systems  

NSDL National Science Digital Library

Introduction to applied linear algebra and linear dynamical systems, with applications to circuits, signal processing, communications, and control systems.Topics include: Least-squares approximations of over-determined equations and least-norm solutions of underdetermined equations. Symmetric matrices, matrix norm and singular value decomposition. Eigenvalues, left and right eigenvectors, and dynamical interpretation. Matrix exponential, stability, and asymptotic behavior. Multi-input multi-output systems, impulse and step matrices; convolution and transfer matrix descriptions. Control, reachability, state transfer, and least-norm inputs. Observability and least-squares state estimation.Prerequisites: Exposure to linear algebra and matrices. You should have seen the following topics: matrices and vectors, (introductory) linear algebra; differential equations, Laplace transform, transfer functions. Exposure to topics such as control systems, circuits, signals and systems, or dynamics is not required, but can increase your appreciation.

Boyd, Stephen

2010-12-24

288

Linear Accelerators  

SciTech Connect

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

Sidorin, A. [Joint Institute for Nuclear Research, Dubna (Russian Federation)

2007-11-26

289

Symmetrized plane waves: 3. nonsymmorphic space groups  

NASA Astrophysics Data System (ADS)

A procedure for systematically constructing symmetrized plane waves, or more generally, arbitrary Bloch-functions, is extended to the case of nonsymmorphic space groups. The technical part to compute those transformations coefficients that are necessary to determine symmetrized plane waves or Bloch-functions, is transferred to a correspondingly tailored software package.

Dirl, R.; Payer, K.; Davies, B. L.

1996-10-01

290

Angular Motion of Spinning Almost Symmetric Missiles.  

National Technical Information Service (NTIS)

An almost symmetric missile is a missile whose zero-spin pitch and yaw frequencies are 'nearly' equal. The angular motion of a spinning almost symmetric missile can be described by five rotating modal vectors. Two of these vectors vanish when the frequenc...

C. H. Murphy

1978-01-01

291

On Symmetric irreducible tensors in d -dimensions  

Microsoft Academic Search

This paper establishes the notion of symmetric irreducible tensors with arbitrary dimensions d̀. These tensors are generalisations of a symmetric traceless, second order tensor and their significance stems from their close connection to spherical harmonics. We introduce the general concepts and derive some fundamental relations with respect to these tensors. Special considerations are given to proofs, because those are hard

H. Ehrentraut; W. Muschik

1998-01-01

292

On the Symmetric Space ?-MODEL Kinematics  

NASA Astrophysics Data System (ADS)

The solvable Lie algebra parametrization of the symmetric spaces is discussed. Based on the solvable Lie algebra gauge two equivalent formulations of the symmetric space sigma model are studied. Their correspondence is established by inspecting the normalization conditions and deriving the field transformation laws.

Yilmaz, Nejat T.

293

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

294

Consequences of a linear two-coordinate geometry for the orbital magnetism and Jahn-Teller distortion behavior of the high spin iron(II) complex Fe[N(t-Bu)2]2.  

PubMed

Mossbauer, EPR, magnetic susceptibility, and DFT studies of the unusual two-coordinate iron(II) amide Fe[N(t-Bu)(2)](2) show that it retains a linear N-Fe-N framework due to the nonbonding delta nature of the (xy, x(2)-y(2)) orbitals. The resulting near-degenerate ground state gives rise to a large magnetic moment and a remarkably large internal hyperfine field. The results confirm that extraordinary orbital magnetic effects can arise in linear transition metal complexes in which orbital degeneracies are not broken by Jahn-Teller or Renner-Teller distortions. PMID:19113855

Reiff, William M; Schulz, Charles E; Whangbo, Myung-Hwan; Seo, Jung In; Lee, Yoon Sup; Potratz, Gregory R; Spicer, Charles W; Girolami, Gregory S

2009-01-21

295

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

SciTech Connect

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

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

2011-07-15

296

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

297

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

298

Heat conduction of symmetric lattices.  

PubMed

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

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

2013-06-28

299

Symmetric diffeomorphic registration of fibre orientation distributions.  

PubMed

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

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

2011-02-18

300

Subcritical flutter in the acoustics of friction of the spinning rotationally symmetric elastic continua  

Microsoft Academic Search

Linearized models of elastic bodies of revolution, spinning about their symmetrical axes, possess the eigen- frequency plots with respect to the rotational speed, which form a mesh with double semi-simple eigenfre- quencies at the nodes. At contact with friction pads, the rot ating continua, such as the singing wine glass or the squealing disc\\/drum brake, start to vibrate because of

O. N. Kirillov

301

Quasi-steady symmetric regimes of a rotating annulus differentially heated on the horizontal boundaries  

Microsoft Academic Search

The symmetric flows in a rotating annulus with horizontal boundaries maintained at temperatures as linear functions of radial distance, and with vertical boundaries thermally insulated are investigated for the infinitesimal Ekman number and the product of the Prandtl and thermal Rossby numbers ranging from infinitesimal to 0(10). The heat transfer is by conduction for the infinitesimal value of this product;

Charles Quon

1980-01-01

302

Test of a symmetrical four-detector compton polarimeter using low temperature nuclear orientation  

Microsoft Academic Search

A symmetrical four-detector Compton polarimeter was used to measure the linear polarization of gamma-rays emitted from nuclei oriented by the hyperfine interaction at low temperature. Its polarization detection efficiency was determined in the range 0.3 1.4 MeV and compared with some other polarimeters.

J. K. Deng; J. H. Hamilton; A. V. Ramayya; J. Rikovska; N. J. Stone; W. L. Croft; R. B. Piercey; J. C. Morgan; P. F. Mantica

1992-01-01

303

Test of a symmetrical four-detector compton polarimeter using low temperature nuclear orientation  

Microsoft Academic Search

A symmetrical four-detector Compton polarimeter was used to measure the linear polarization of gamma-rays emitted from nuclei\\u000a oriented by the hyperfine interaction at low temperature. Its polarization detection efficiency was determined in the range\\u000a 0.3–1.4 MeV and compared with some other polarimeters.

J. K. Deng; J. H. Hamilton; A. V. Ramayya; J. Rikovska; N. J. Stone; W. L. Croft; R. B. Piercey; J. C. Morgan

1992-01-01

304

Equations of motion for a system of rotating spherically symmetric bodies  

Microsoft Academic Search

The relativistic equations of motion for a system of rotating spherically symmetric bodies are reduced to Lagrange equations of the first kind. Introducing generalized momentum leads to a generalization of the force of universal gravitation. The obtained Lagrangian agrees with previous ones only up to terms containing linear velocities, the part of the Lagrange function responsible for rotation not being

B. G. Tepikin

1975-01-01

305

Stability of symmetrical rotor supported in flexibly mounted, self-acting gas journal bearings  

Microsoft Academic Search

This paper describes the results of numerical investigations of the stability problem of the rigid symmetrical rotor, supported in two self-acting gas journal bearings. Bushes of the bearings are mounted on a system of linear springs and viscous dampers. When the stiffness and damping coefficients of these springs and dampers are chosen correctly, it is possible to avoid the self-excited

Krzysztof Czo?czy?ski; Krzysztof Marynowski

1996-01-01

306

Theory of Ventilating or Cavitating Flows about Symmetric Surface-Piercing Struts.  

National Technical Information Service (NTIS)

Two stable states of high-speed strut flow are considered in three dimensions under linear boundary conditions. The strut is thin, symmetric, without angle of attack, and has base-ventilation or base cavitation without side cavitation. The strut and cavit...

B. Yim

1975-01-01

307

Experimental characterization of qutrits using symmetric informationally complete positive operator-valued measurements  

Microsoft Academic Search

Generalized quantum measurements [also known as positive operator-valued measures (POVMs)] are of great importance in quantum information and quantum foundations but are often difficult to perform. We present an experimental approach which can in principle be used to perform arbitrary POVMs in a linear-optical context. One of the most interesting POVMs, the symmetric informationally complete (SIC) POVM, is the most

Z. E. D. Medendorp; F. A. Torres-Ruiz; L. K. Shalm; G. N. M. Tabia; C. A. Fuchs; A. M. Steinberg

2011-01-01

308

Estimation of phase for noisy linear phase signals  

Microsoft Academic Search

It is well-known that a discrete-time symmetric signal has a linear-phase Fourier transform. This paper describes a procedure for estimating the parameters associated with a linear-phase signal from noisy measurements. When the data being modeled is composed of a linear-phase signal corrupted by additive Gaussian noise, the approach taken results in maximum-likelihood estimates of the linear-phase parameters. The Fisher information

Ramakrishna Kakarala; James A. Cadzow

1996-01-01

309

Symmetric-Galerkin BEM simulation of fracture with frictional contact  

NSDL National Science Digital Library

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

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

2003-04-09

310

Asymmetric wave propagation through nonlinear PT-symmetric oligomers  

NASA Astrophysics Data System (ADS)

In the present paper, we consider nonlinear PT-symmetric dimers and trimers (more generally, oligomers) embedded within a linear Schrödinger lattice. We examine the stationary states of such chains in the form of plane waves, and analytically compute their reflection and transmission coefficients through the nonlinear PT symmetric oligomer, as well as the corresponding rectification factors which clearly illustrate the asymmetry between left and right propagation in such systems. We examine not only the existence but also the dynamical stability of the plane wave states and interestingly find them to be unstable except in the vicinity of the linear limit. Lastly, we generalize our numerical considerations to the more physically relevant case of Gaussian initial wavepackets and confirm that the asymmetry in the transmission properties persists in the case of such wavepackets, as well. The role of potential asymmetries in the nonlinearity or in the gain/loss pattern is also considered. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.

D'Ambroise, J.; Kevrekidis, P. G.; Lepri, S.

2012-11-01

311

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

312

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

313

Dynamics of charged plane symmetric gravitational collapse  

NASA Astrophysics Data System (ADS)

In this paper, we study dynamics of the charged plane symmetric gravitational collapse. For this purpose, we discuss non-adiabatic flow of a viscous fluid and deduce the results for adiabatic case. The Einstein and Maxwell field equations are formulated for general plane symmetric spacetime in the interior. Junction conditions between the interior and exterior regions are derived. For the non-adiabatic case, the exterior is taken as plane symmetric charged Vaidya spacetime while for the adiabatic case, it is described charged plane symmetric spacetime. Using Misner and Sharp formalism, we obtain dynamical equations to investigate the effects of different forces over the rate of collapse. In non-adiabatic case, a dynamical equation is joined with transport equation of heat flux. Finally, a relation between the Weyl tensor and energy density is found.

Sharif, M.; Siddiqa, Aisha

2011-01-01

314

Gaussian Multiplicative Chaos for Symmetric Isotropic Matrices  

NASA Astrophysics Data System (ADS)

Motivated by isotropic fully developed turbulence, we define a theory of symmetric matrix valued isotropic Gaussian multiplicative chaos. Our construction extends the scalar theory developed by J.P. Kahane in 1985.

Chevillard, Laurent; Rhodes, Rémi; Vargas, Vincent

2013-02-01

315

Nonlocality and entanglement for symmetric states  

NASA Astrophysics Data System (ADS)

In this paper, building on some recent progress combined with numerical techniques, we shed some light on how the nonlocality of symmetric states is related to their entanglement properties and on their potential usefulness in quantum information processing. We use semidefinite programming techniques to devise a device-independent classification of three 4-qubit states into two classes inequivalent under local unitaries and permutation of systems. We study nonlocal properties when the number of parties grows large for two important classes of symmetric states: W states and GHZ states, showing that they behave differently under the inequalities we consider. We also discuss the monogamy arising from the nonlocal correlations of symmetric states. We show that although monogamy in a strict sense is not guaranteed for all symmetric states, strict monogamy is achievable for all Dicke states when the number of parties goes to infinity.

Wang, Zizhu; Markham, Damian

2013-01-01

316

Postpartum Peripheral Symmetrical Gangrene: A Case Report  

PubMed Central

Background Symmetrical peripheral gangrene is usually associated with underlying medical problems and it is seldom seen in pregnancy. Sepsis though common in a setting of delivery by unskilled midwife is rarely accompanied by symmetrical gangrene. Case Presentation We report a case of symmetrical peripheral gangrene which occurred in the winter, triggered possibly by sepsis and a single dose of ergot. A high index of suspicion, early diagnosis and intervention with appropriate measures will result in favorable outcome in such cases. Conclusion Although postpartum period is of high risk for sepsis and use of ergot alkaloids is common in labor but occurrence of peripheral symmetrical gangrene is rare. A high index of suspicion for the diagnosis and timely intervention will prevent irreparable damage and loss of limb.

Sharma, Lipi; Mehta, Sumita; Rajaram, Shalini; Aggarwal, Rachna; Gupta, Sanjay; Goel, Neerja

2012-01-01

317

Symmetric Space ?-MODEL Dynamics:. Current Formalism  

NASA Astrophysics Data System (ADS)

After explicitly constructing the symmetric space sigma model Lagrangian in terms of the coset scalars of the solvable Lie algebra gauge in the current formalism, we derive the field equations of the theory.

Yilmaz, Nejat T.

318

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

319

Symmetric informationally complete measurements of arbitrary rank  

Microsoft Academic Search

There has been much interest in so-called SIC-POVMs, i.e., rank 1 symmetric informationally complete positive operator valued\\u000a measures. In this paper we discuss the larger class of POVMs that are symmetric and informationally complete, but not necessarily\\u000a rank 1. This class of POVMs is of some independent interest. In particular it includes a POVM that is closely related to the

D. M. Appleby

2007-01-01

320

Vibration of a sandwich plate strip of linearly varying thickness  

Microsoft Academic Search

Free transverse vibration of a sandwich plate strip having a core of linearly varying thickness and symmetrical faces of constant thickness is considered. The materials of the core and the faces are assumed to be linearly elastic and isotropic. The effects of transverse shear deformation and rotary inertia are included in the core as well as in the faces. The

A. P. Gupta; R. R. Bhargava

1993-01-01

321

Benign symmetrical lipomatosis and pellagra associated with alcoholism.  

PubMed

A 42-year-old male patient, alcoholic, presented showing signs of tumors in the neck and around the shoulders, scaly, erythematous-violaceous lesions and some bullous lesions in sun-exposed areas of upper and lower limbs. Based on clinical features, laboratory tests and imaging studies we have established the diagnosis of pellagra associated with benign symmetrical lipomatosis, both justified by chronic alcoholism. Treated with intravenous B-complex and oriented about the importance of alcohol withdrawal, the patient showed complete remission of skin lesions, but with no change in the lipomatosis. PMID:22281911

Filgueiras, Fernanda de Marca; Stolarczuk, Dionne de Almeida; Gripp, Alexandre Carlos; Succi, Isabel Cristina Brasil

322

The parallel decomposition of linear programs  

SciTech Connect

This thesis introduces a new calculus for manipulating linear-program decomposition schemes. A linear program is represented by a communication network, which is decomposed by splitting nodes in two, and a transformation is defined to recover subproblems from the network. We also define a dual-symmetric oracle that provides solutions to linear programs, and can be performed by the simplex method, nested decomposition, and finally, parallel decomposition. Two important classes of linear program serve as examples for the above calculus: staircase linear programs and stochastic linear programs. For the former case, a sophisticated yet experimental computer code has been written for an IBM 3090/600E with six processors. The code performs the parallel decomposition algorithm and is tested on twenty-two small to medium sized real-world'' problems. Experiments show that in addition to speedups provided by decomposition alone, performance is improved by using parallel processors. 57 refs., 33 figs., 14 tabs.

Entriken, R.

1989-11-01

323

The parallel decomposition of linear programs  

SciTech Connect

This thesis introduces a new calculus for manipulating linear-program decomposition schemes. A linear program is represented by a communication network, which is decomposed by splitting nodes in two, and a transformation is defined to recover subproblems from the network. The author also defines a dual-symmetric oracle that provides solutions to linear programs, and can be performed by the simplex method, nested decomposition, and finally, parallel decomposition. Two important classes of linear program serve as examples for the above calculus: staircase linear programs and stochastic linear programs. For the former case, a sophisticated yet experimental computer code has been written for an IBM 3090/600E with six processors. The code performs the parallel decomposition algorithm and is tested on twenty-two small to medium sized real-world problems. Experiments show that in addition to speedups provided by decomposition alone, performance is improved by using parallel processors.

Entriken, R.

1989-01-01

324

Linear Transformations  

NSDL National Science Digital Library

Created by Stephanie Fitchett of the Connected Curriculum Project, the purpose of this module is to examine linear transformations, particularly those from R^2 to R^2. The is part of a larger collection of learning modules hosted by Duke University.

Fitchett, Stephanie

2010-05-20

325

PT-symmetric sinusoidal optical lattices at the symmetry-breaking threshold  

SciTech Connect

The PT-symmetric potential V{sub 0}[cos(2{pi}x/a)+i{lambda}sin(2{pi}x/a)] has a completely real spectrum for {lambda}{<=}1 and begins to develop complex eigenvalues for {lambda}>1. At the symmetry-breaking threshold {lambda}=1 some of the eigenvectors become degenerate, giving rise to a Jordan-block structure for each degenerate eigenvector. In general this is expected to result in a secular growth in the amplitude of the wave. However, it has been shown in a recent paper by Longhi, by numerical simulation and by the use of perturbation theory, that for a broad initial wave packet this growth is suppressed, and instead a saturation leading to a constant maximum amplitude is observed. We revisit this problem by explicitly constructing the Bloch wave functions and the associated Jordan functions and using the method of stationary states to find the dependence on the longitudinal distance z for a variety of different initial wave packets. This allows us to show in detail how the saturation of the linear growth arises from the close connection between the contributions of the Jordan functions and those of the neighboring Bloch waves.

Graefe, Eva-Maria [Mathematics Department, Imperial College, London SW7 2BZ (United Kingdom); Jones, H. F. [Physics Department, Imperial College, London SW7 2BZ (United Kingdom)

2011-07-15

326

Eigenvalue structure of a Bose–Einstein condensate in a {PT}-symmetric double well  

NASA Astrophysics Data System (ADS)

We study a Bose–Einstein condensate in a {PT}-symmetric double-well potential where particles are coherently injected in one well and removed from the other well. In mean-field approximation the condensate is described by the Gross–Pitaevskii equation thus falling into the category of nonlinear non-Hermitian quantum systems. After extending the concept of {PT} symmetry to such systems, we apply an analytic continuation to the Gross–Pitaevskii equation from complex to bicomplex numbers and show a thorough numerical investigation of the four-dimensional bicomplex eigenvalue spectrum. The continuation introduces additional symmetries to the system which are confirmed by the numerical calculations and furthermore allows us to analyse the bifurcation scenarios and exceptional points of the system. We present a linear matrix model and show the excellent agreement with our numerical results. The matrix model includes both exceptional points found in the double-well potential, namely an EP2 at the tangent bifurcation and an EP3 at the pitchfork bifurcation. When the two bifurcation points coincide the matrix model possesses four degenerate eigenvectors. Close to that point we observe the characteristic features of four interacting modes in both the matrix model and the numerical calculations, which provides clear evidence for the existence of an EP4.

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

2013-09-01

327

Symmetric positive 4th order tensors & their estimation from diffusion weighted MRI.  

PubMed

In Diffusion Weighted Magnetic Resonance Image (DW-MRI) processing a 2nd order tensor has been commonly used to approximate the diffusivity function at each lattice point of the DW-MRI data. It is now well known that this 2nd-order approximation fails to approximate complex local tissue structures, such as fibers crossings. In this paper we employ a 4th order symmetric positive semi-definite (PSD) tensor approximation to represent the diffusivity function and present a novel technique to estimate these tensors from the DW-MRI data guaranteeing the PSD property. There have been several published articles in literature on higher order tensor approximations of the diffusivity function but none of them guarantee the positive semi-definite constraint, which is a fundamental constraint since negative values of the diffusivity coefficients are not meaningful. In our methods, we parameterize the 4th order tensors as a sum of squares of quadratic forms by using the so called Gram matrix method from linear algebra and its relation to the Hilbert's theorem on ternary quartics. This parametric representation is then used in a nonlinear-least squares formulation to estimate the PSD tensors of order 4 from the data. We define a metric for the higher-order tensors and employ it for regularization across the lattice. Finally, performance of this model is depicted on synthetic data as well as real DW-MRI from an isolated rat hippocampus. PMID:17633709

Barmpoutis, Angelos; Jian, Bing; Vemuri, Baba C; Shepherd, Timothy M

2007-01-01

328

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

329

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

330

Linear Models  

NSDL National Science Digital Library

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

Wattenberg, Frank

1997-01-01

331

The effects of linear assembly of two carbazole groups on acid-base and DNA-binding properties of a ruthenium(II) complex  

NASA Astrophysics Data System (ADS)

A novel Ru(II) complex of [Ru(bpy)2(Hbcpip)](ClO4)2 {where bpy = 2,2-bipyridine, Hbcpip = 2-(4-(9H-3,9'-bicarbazol-9-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline} is synthesized and characterized. Calf-thymus DNA-binding properties of the complex were studied by UV-vis absorption and luminescence titrations, steady-state emission quenching by [Fe(CN)6]4-, DNA competitive binding with ethidium bromide, thermal denaturation and DNA viscosity measurements. The results indicate that the complex partially intercalated into the DNA with a binding constant of (5.5 ± 1.4) × 105 M-1 in buffered 50 mM NaCl. The acid-base properties of the complex were also studied by UV-visible and luminescence spectrophotometric pH titrations, and ground- and excited-state acidity ionization constant values were derived.

Chen, Xi; Xue, Long-Xin; Ju, Chun-Chuan; Wang, Ke-Zhi

2013-07-01

332

A modified direct preconditioner for indefinite symmetric Toeplitz systems  

SciTech Connect

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

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

1992-11-01

333

A modified direct preconditioner for indefinite symmetric Toeplitz systems  

SciTech Connect

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

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

1992-11-01

334

Inflation in spherically symmetric inhomogeneous models  

SciTech Connect

Exact analytical solutions of Einstein's equations are found for a spherically symmetric inhomogeneous metric in the presence of a massless scalar field with a flat potential. The process of isotropization and homogenization is studied in detail. It is found that the time dependence of the metric becomes de Sitter for large times. Two cases are studied. The first deals with a homogeneous scalar field, while the second with a spherically symmetric inhomogeneous scalar field. In the former case the metric is of the Robertson-Walker form, while the latter is intrinsically inhomogeneous. 16 refs.

Stein-Schabes, J.A.

1986-11-01

335

Turbulent Parameter Evolution in Madison Symmetric Torus RFP Plasmas  

NASA Astrophysics Data System (ADS)

Using Fourier analysis and chaos theory, the turbulent parameters have been used to characterize turbulence in many different plasma systems. The Fourier components measure the characteristic frequency that is associated with instabilities that drive turbulence, the amount of energy associated with turbulence and the rate at which that energy moves between scales. The chaos components measure the complexity and volatility of the fluctuations. The Madison Symmetric Torus provides a plethora of plasma regimes to study turbulence and its associated transitions. Magnetic field fluctuations measurements have been made during the ramp-up, sawtooth crash, and equilibrium phases of a standard discharge, along with the increased confinement period during poloidal pulse current drive (PPCD). While the Fourier components of the turbulent parameters are independent of plasma current, the chaotic components show that the complexity and volatility are dependent on both plasma current and density.

Titus, J. B.; Mezonlin, E. D.; Alexander, A. B.; Johnson, J. A., III

2012-10-01

336

Adiabatic and Viscous Simulations of Symmetric Instability: Structure, Evolution, and Energetics.  

NASA Astrophysics Data System (ADS)

This paper reports on simulations of dry-adiabatic and viscous symmetric instability circulations with a two-dimensional research version of the French Weather Service Limited Area Model PERIDOT. The simulations of an idealized two-dimensional case of a dry symmetric instability presented here constitute a preliminary work to future real case studies.As a first step, the capacity of the model to simulate circulations of the dry inviscid symmetric instability that are in agreement with the linear hydrostatic theory has been verified. This has allowed the design and verification of diagnostic tools. In order to use these diagnostics on simulations of real data cases, a spectral method has been developed to separate the basic state from the symmetric instability circulations. For all of our simulations, the energetics of the circulation show that the circulations draw their kinetic energy mainly from the term linked to the basic vertical shear and the correlation of the vertical and longitudinal components of the motion of the perturbation.Adequate horizontal and vertical resolution and diffusion formulation are found to be necessary to simulate a reasonable numerical evolution of the symmetric instability circulations. In particular, the nonlinear evolution of the dry viscous symmetric instability circulations has been studied by the inclusion of a realistic turbulent diffusion: a complete life cycle is obtained, and a quasi neutrality is reached at the end of the integrations. These simulations provide a first approach to the adjustment problem (i.e., how can the neutrality with respect to symmetric instability, which is frequently observed in real bands, be reached?) and of its representation in a numerical model.

Ducrocq, V.

1993-01-01

337

Symmetric displacement algorithms for the timing analysis of large scale circuits  

Microsoft Academic Search

A number of new techniques for the time domain simulation of MOS circuits based on 'one-sweep' symmetric displacement methods are proposed. Following standard numerical analysis procedures for the characterization of integration methods, the numerical properties of these new techniques are investigated by introducing test problems that are simple enough to be studied analytically and yet complex enough to provide insight

G. de Micheli; A. R. Newton; A. Sangiovanni-Vincentelli

1983-01-01

338

Exact expression of the ground-state energy for the symmetric anderson model  

NASA Astrophysics Data System (ADS)

The exact expression of the ground-state energy for the symmetric Anderson model is obtained with the use of the Wiegmann approach. It is found that some of the quasi-momenta appearing in Wiegmann's paper are necessarily complex to obtain the expression of the ground-state energy.

Kawakami, Norio; Okiji, Ayao

1981-12-01

339

Two loop QCD vertices at the symmetric point  

NASA Astrophysics Data System (ADS)

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 ? 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.

2011-10-01

340

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

341

Spherically symmetric cosmological spacetimes with dust and radiation — numerical implementation  

NASA Astrophysics Data System (ADS)

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; Regis, Marco; Clarkson, Chris

2013-10-01

342

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

343

Species Classification and Rotational Energy Level Patterns of Non-Linear Triatomic Molecules  

Microsoft Academic Search

With the object of making existing knowledge more readily available, the quantized energy levels of symmetrical and asymmetrical tops are discussed from the viewpoint of their classification into species defined by symmetry operations; and simple species nomenclatures are proposed. These are then applied in a discussion of the rotational levels of symmetrical non-linear triatomic molecules AB2. With SO2 as an

Robert S. Mulliken

1941-01-01

344

Probing the electronic communication of linear heptanickel and nonanickel string complexes by utilizing two redox-active [Ni2(napy)4]3+ moieties.  

PubMed

Two extended nickel string complexes, [Ni(7)(bnapy)(4)Cl(2)](Cl)(2) (2) and [Ni(9)(bnapya)(4)Cl(2)](PF(6))(2) (3) (bnapy(2-) = 2,6-bis(1,8-naphthyridylamido)pyridine and bnapya(3-) = bis(6-(1,8-naphthyridylamido)pyridyl)amido), which possess two redox-active [Ni(2)(napy)(4)](3+) units, were synthesized and characterized. The electronic communication between the two redox-active units in both complexes can be investigated not only by magnetic measurements but also by analyzing the difference between two consecutive one-electron oxidation peaks (DeltaE(1/2)) of 2 and 3. The antiferromagnetic coupling between the two [Ni(2)(napy)(4)](3+) fragments become weaker as the metal frameworks are elongated (J = -13.21 and -1.48 cm(-1) for 2 and 3, respectively). Moreover, the DeltaE(1/2) values of 2 and 3 are 110 and 84 mV, respectively, which are smaller than that (300 mV) of their pentanickel analogue [Ni(5)(bna)(4)(Cl)(2)](PF(6))(2) (bna(-) = bisnaphthyridylamido) (1). These DeltaE(1/2) values indicate that the electronic communication decreases with increasing number of inner diamagnetic nickel ions in nickel string complexes. PMID:20372713

Hua, Shao-An; Liu, Isiah Po-Chun; Hasanov, Hasan; Huang, Gin-Chen; Ismayilov, Rayyat Huseyn; Chiu, Chien-Lan; Yeh, Chen-Yu; Lee, Gene-Hsiang; Peng, Shie-Ming

2010-01-28

345

A design technique for symmetric dualband filters  

Microsoft Academic Search

This work describes a method for designing a class of microwave filters presenting a rejection bandwidth inside the passband; these filters are then characterized by two passbands separated by a stopband, which is created by suitably inserting transmission zeros inside the original passband. In case of passbands of equal extension and with the stopband symmetrically displaced between the passbands, the

Giuseppe Macchiarella; Stefano Tamiazzo

2005-01-01

346

Design of Rotationally Symmetric Triode Electron Guns.  

National Technical Information Service (NTIS)

The properties of the symmetric triode electron gun are given in design rules as a function of its geometry and the applied potentials. A numerical method to simulate electron guns is described. The simulation is sufficiently accurate to replace a large n...

M. H. L. M. Vandenbroek

1986-01-01

347

Scaling model for symmetric star polymers  

Microsoft Academic Search

Neutron scattering data from symmetric star polymers with six poly (urethane-ether) arms, chemically bonded to a C-60 molecule are fitted using a new scaling model and scattering function. The new scaling function can describe both good solvent and theta solvent conditions as well as resolve deviations in chain conformation due to steric interactions between star arms. The scaling model quantifies

Ram Ramachandran; Durgesh K. Rai; Gregory Beaucage

2010-01-01

348

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

349

Introduction to left-right symmetric models.  

National Technical Information Service (NTIS)

We motivate left-right symmetric models by the possibility of spontaneous parity breaking. Then we describe the multiplets and the Lagrangian of such models. Finally we discuss lower bounds on the right-handed scale. (author). (Atomindex citation 25:01224...

W. Grimus

1993-01-01

350

Left-Right Symmetric Electroweak Models.  

National Technical Information Service (NTIS)

We present a critical analysis of the spontaneous symmetry breaking and the Higgs sector of the conventional SU(2)(sub L)(circle times)SU(2)(sub R)(circle times)U(1)(sub B-L) left-right symmetric theory involving bi-doublet and triplet Higgs fields. We ex...

F. I. Olness

1989-01-01

351

Multifrontal parallel distributed symmetric and unsymmetric solvers  

Microsoft Academic Search

We consider the solution of both symmetric and unsymmetric systems of sparselinear equations. A new parallel distributed memory multifrontal approach isdescribed. To handle numerical pivoting efficiently, a parallel asynchronousalgorithm with dynamic scheduling of the computing tasks has been developed. Wediscuss some of the main algorithmic choices and compare both implementationissues and the performance of the LDLTand LU factorizations. Performanceanalysis on

P. R. Amestoy; I. S. Duff; J Y L'Excellent

1998-01-01

352

Symmetrical connector for solar panel arrays  

Microsoft Academic Search

The disclosed symmetrical plug and socket connector may be installed in a solar panel array so that the connector is directed towards the adjacent panel for forming an interconnect by the shortest possible route. The connector socket is an elongated, substantially rectangular housing having a groove formed about the entire periphery thereof adjacent one side and an annular bore extending

Bunnell

1981-01-01

353

REAL FORMS OF HERMITIAN SYMMETRIC SPACES1  

Microsoft Academic Search

Introduction. The results we give here only begin to answer the follow­ ing general problems: Let AT be a hermitian symmetric domain, T a group acting holomorphically and discontinuously, and U = T\\\\X the quotient. Then, by Kodaira if U is compact and smooth, or, by Baily-Borel if just {\\/has finite volume (and T arithmetic), U is algebraic. One can

HARRIS A. JAFFEE

354

Symmetric space description of carbon nanotubes  

NASA Astrophysics Data System (ADS)

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 parametrization 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) × U(1)] belonging to the DIII-odd Cartan class. We rederive the leading-order correction to the conductance of the perfectly conducting channel \\langle \\ln \\delta g \\rangle and its variance Var(ln ?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 \\mathrm {Var}(\\ln \\delta g)/\\langle \\ln \\delta g\\rangle , and as a by-product a novel expression for the localization length for the most general case of a symmetric space with BCm root system, in which all three types of roots are present.

Caselle, Michele; Magnea, Ulrika

2006-01-01

355

Dissociative Recombination of Highly Symmetric Polyatomic Ions  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

356

ECG compression using discrete symmetric wavelet transform  

Microsoft Academic Search

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

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

1995-01-01

357

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

358

A Maple Package for Symmetric Functions  

Microsoft Academic Search

We describe the man features of a package of Maple programs for manipulating symmetric polynomials and related structures. Among the highlights of the package are (1) a collection of procedures for converting between polynomial expressions involving several fundamental bases, and (2) a general mechanism that allows the user to easily add new bases to the existing collection. The latter facilitates

John R. Stembridge

1995-01-01

359

Asymmetric Versus Symmetric Pulses for Cortical Microstimulation  

Microsoft Academic Search

Intracortical microstimulation (ICMS), which has shown promise in the visual, auditory and somatosensory sys- tems as a platform for sensory prostheses, typically relies on charged balanced, symmetric, biphasic stimulation. However, neural stimulation models as well as experiments conducted in cochlear implant users have suggested that charge balanced asymmetric pulses could generate lower detection thresholds for stimulation in terms of charge

Andrew S. Koivuniemi; Kevin J. Otto

2011-01-01

360

Symmetrization of cyclic sigma-telluranes  

SciTech Connect

The authors examine reactions involving cyclic sigma-telluranes. Refluxing 5,5-dichlorodibenzotellurophene with tellurium tetrachloride in o-dichlorobenzene results in symmetrization and the formation of 2,2'-bis(trichlorotelluro)diphenyl in high yield. The other compounds formed and described are polymeric ditelluride, dibenzotellurophene, and dimethyltellurium dibromide.

Sadekov, I.D.; Rivkin, B.B.; Maslakov, A.G.; Minkin, V.I.

1987-09-01

361

Models of helically symmetric binary systems  

NASA Astrophysics Data System (ADS)

Results from helically symmetric scalar-field models and first results from a convergent helically symmetric binary neutron-star code are reported here; these are models stationary in the rotating frame of a source with constant angular velocity ?. In the scalar-field models and the neutron-star code, helical symmetry leads to a system of mixed elliptic hyperbolic character. The scalar-field models involve nonlinear terms of the form ?3, (??)2 and ?squ? that mimic nonlinear terms of the Einstein equation. Convergence is strikingly different for different signs of each nonlinear term; it is typically insensitive to the iterative method used, and it improves with an outer boundary in the near zone. In the neutron-star code, one has no control on the sign of the source, and convergence has been achieved only for an outer boundary less than ~1 wavelength from the source or for a code that imposes helical symmetry only inside a near zone of that size. The inaccuracy of helically symmetric solutions with appropriate boundary conditions should be comparable to the inaccuracy of a waveless formalism that neglects gravitational waves, and the (near zone) solutions we obtain for waveless and helically symmetric BNS codes with the same boundary conditions nearly coincide.

Yoshida, Shin'ichirou; Bromley, Benjamin C.; Read, Jocelyn S.; Uryu, Koji; Friedman, John L.

2006-08-01

362

Realizability of stationary spherically symmetric transonic accretion.  

PubMed

The spherically symmetric stationary transonic (Bondi) flow is considered a classic example of an accretion flow. This flow, however, is along a separatrix, which is usually not physically realizable. We demonstrate, using a pedagogical example, that it is the dynamics which selects the transonic flow. PMID:12513398

Ray, Arnab K; Bhattacharjee, J K

2002-12-10

363

Regeneration of Symmetrical Hindlimbs in Larval Salamanders  

Microsoft Academic Search

The complete circle rule of the polar coordinate model of pattern regulation was tested for regenerating hindlimbs of Ambystoma larvae. The hindlimbs were made symmetrical in the circumference of either the thigh or the shank, and their ability to regenerate from both levels was observed. Thighs composed of two anterior halves failed to regenerate, whereas thighs composed of two posterior

David L. Stocum

1978-01-01

364

Conversion Functions for Symmetric Key Ciphers  

Microsoft Academic Search

As a general design criterion, a symmetric key cipher should not be closed under functional com- position due to the implications on the security of the cipher. However, there are scenarios in which this prop- erty is desirable and can be obtained without reducing the security of a cipher by increasing the computational workload of the cipher. We expand the

Debra L. Cook; Angelos D. Keromytis

365

Geometrical Symmetry in Symmetric Galerkin BEM.  

National Technical Information Service (NTIS)

We consider a symmetric boundary integral formulation associated with a mixed boundary value problem defined on a domain Omega is an element of the set of real numbers(2) with piecewise smooth boundary Gamma. We assume that Omega is mapped onto itself by ...

A. Aimi M. Diligenti

2001-01-01

366

Symmetric Stereo Matching for Occlusion Handling  

Microsoft Academic Search

In this paper, we propose a symmetric stereo model to han- dle occlusion in dense two-frame stereo. Our occlusion reasoning is directly based on the visibility constraint that is more general than both ordering and uniqueness con- straints used in previous work. The visibility constraint requires occlusion in one image and disparity in the other to be consistent. We embed

Jian Sun; Yin Li; Sing Bing Kang; Heung-Yeung Shum

2005-01-01

367

Iris Recognition Using Circular Symmetric Filters  

Microsoft Academic Search

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

Li Ma; Yunhong Wang; Tieniu Tan

2002-01-01

368

Rounding in Symmetric Matrices and Undirected Graphs  

Microsoft Academic Search

We consider the problem of rounding the entries of a matrix without distorting the row, column, and grand totals. This problem arises in controlling statistical disclosure, in data analysis, and elsewhere. There are algorithms in the literature which produce roundings that are “tight” in the sense of distorting the totals very little. We concentrate on the case of symmetric matrices.

Pavol Hell; David G. Kirkpatrick; Brenda Li

1996-01-01

369

Circular symmetrization and extremal Robin conditions  

Microsoft Academic Search

: We study the average temperature in a homogeneous disk subject touniform heating in its interior and Newton's law of cooling, hv + @v=@n = 0, onits boundary. More precisely, among those h taking values in a prescribed interval,and of prescribed mean, we identify the minimizer and a maximizer of the averagetemperature. The latter characterization makes use of circular symmetrization.

Steven J. Cox; Bernhard Kawohl

1999-01-01

370

Cracked Shells under Skew-Symmetric Loading.  

National Technical Information Service (NTIS)

The general problem of a shell containing a through crack in one of the principal planes of curvature and under general skew-symmetric loading is considered. By employing a Reissner type shell theory which takes into account the effect of transverse shear...

F. Delale

1981-01-01

371

Rule learning approaches for symmetric multiplayer games  

Microsoft Academic Search

This paper describes a series of experiments involving rule learning for Samurai, a symmetric multiplayer strategy game. Rule based artificial intelligence is commonly used in a wide variety of computer strategy games. Automated rule learning processes have been used to derive rules both to improve the quality of AI play and to illuminate possible strategies and tactics for the games.

John Rushing; John Tiller

2011-01-01

372

Anion dependent self-assembly of a linear hexanuclear Yb(iii) salen complex with enhanced near-infrared (NIR) luminescence properties.  

PubMed

Reactions of H2salen (H2L, N,N'-ethylene bis(salicylideneimine)) with Yb(CF3SO3)3, Yb(OAc)3·4H2O and Yb(NO3)3·6H2O in MeOH-EtOH under reflux gave NIR luminescent complexes [Yb6L9(H2L)2] (), [Yb3L3(HL)(OH)2] () and [Yb2L2(H2L)2(NO3)(MeOH)2]·NO3 (), respectively. PMID:24019025

Yang, Xiaoping; Oye, Michael M; Jones, Richard A; Huang, Shaoming

2013-09-24

373

Probing nonequilibrium fluctuations through linear response  

NASA Astrophysics Data System (ADS)

Linear response analysis in the nonequilibrium steady state (Gaussian regime) provides two independent fluctuation-response relations. One, in the form of the symmetric matrix, manifests the departure from the equilibrium formula through the quantity so-called irreversible circulation. The other, in the antisymmetric form, connects the asymmetries in the fluctuation and the response function. These formulas represent characteristic features of fluctuations far from equilibrium, which have no counterparts in thermal equilibrium.

Sakaue, Takahiro; Ohta, Takao

2008-05-01

374

Trivalent Polygonal Complexes of Nonpositive Curvature and Platonic Symmetry  

Microsoft Academic Search

In this paper we study a natural generalization of Platonic solids: two-dimensional simply connected polygonal complexes with flag transitive group of combinatorial automorphisms. Our results give an almost complete description of such symmetric complexes with constant valency 3. The initial local data for the construction of such a complex are a regular k-gon and a (highly symmetric) graph L: the

1998-01-01

375

Symmetric displacement algorithms for the timing analysis of large scale circuits  

NASA Astrophysics Data System (ADS)

A number of new techniques for the time domain simulation of MOS circuits based on 'one-sweep' symmetric displacement methods are proposed. Following standard numerical analysis procedures for the characterization of integration methods, the numerical properties of these new techniques are investigated by introducing test problems that are simple enough to be studied analytically and yet complex enough to provide insight on how they will behave in general. The implementation of these methods in timing simulators is described and some experimental results that emphasize the superior accuracy and stability of symmetric displacement techniques are given.

de Micheli, G.; Newton, A. R.; Sangiovanni-Vincentelli, A.

1983-07-01

376

Compressive sensing with dispersion compensation on non-linear wavenumber sampled spectral domain optical coherence tomography  

PubMed Central

We propose a novel compressive sensing (CS) method on spectral domain optical coherence tomography (SDOCT). By replacing the widely used uniform discrete Fourier transform (UDFT) matrix with a new sensing matrix which is a modification of the non-uniform discrete Fourier transform (NUDFT) matrix, it is shown that undersampled non-linear wavenumber spectral data can be used directly in the CS reconstruction. Thus k-space grid filling and k-linear mask calibration which were proposed to obtain linear wavenumber sampling from the non-linear wavenumber interferometric spectra in previous studies of CS in SDOCT (CS-SDOCT) are no longer needed. The NUDFT matrix is modified to promote the sparsity of reconstructed A-scans by making them symmetric while preserving the value of the desired half. In addition, we show that dispersion compensation can be implemented by multiplying the frequency-dependent correcting phase directly to the real spectra, eliminating the need for constructing complex component of the real spectra. This enables the incorporation of dispersion compensation into the CS reconstruction by adding the correcting term to the modified NUDFT matrix. With this new sensing matrix, A-scan with dispersion compensation can be reconstructed from undersampled non-linear wavenumber spectral data by CS reconstruction. Experimental results show that proposed method can achieve high quality imaging with dispersion compensation.

Xu, Daguang; Huang, Yong; Kang, Jin U.

2013-01-01

377

Compressive sensing with dispersion compensation on non-linear wavenumber sampled spectral domain optical coherence tomography.  

PubMed

We propose a novel compressive sensing (CS) method on spectral domain optical coherence tomography (SDOCT). By replacing the widely used uniform discrete Fourier transform (UDFT) matrix with a new sensing matrix which is a modification of the non-uniform discrete Fourier transform (NUDFT) matrix, it is shown that undersampled non-linear wavenumber spectral data can be used directly in the CS reconstruction. Thus k-space grid filling and k-linear mask calibration which were proposed to obtain linear wavenumber sampling from the non-linear wavenumber interferometric spectra in previous studies of CS in SDOCT (CS-SDOCT) are no longer needed. The NUDFT matrix is modified to promote the sparsity of reconstructed A-scans by making them symmetric while preserving the value of the desired half. In addition, we show that dispersion compensation can be implemented by multiplying the frequency-dependent correcting phase directly to the real spectra, eliminating the need for constructing complex component of the real spectra. This enables the incorporation of dispersion compensation into the CS reconstruction by adding the correcting term to the modified NUDFT matrix. With this new sensing matrix, A-scan with dispersion compensation can be reconstructed from undersampled non-linear wavenumber spectral data by CS reconstruction. Experimental results show that proposed method can achieve high quality imaging with dispersion compensation. PMID:24049674

Xu, Daguang; Huang, Yong; Kang, Jin U

2013-08-02

378

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

379

Fourier-Transform Infrared Linear Dichroism: Stretched Polyethylene as a Solvent in IR Spectroscopy,  

National Technical Information Service (NTIS)

The infrared linear dichroism of several dozen symmetrical organic molecules of low polarity has been measured on their solid solutions in stretched polyethylene and stretched perdeuterated polyethylene. Both saturated and unsaturated molecules, ranging i...

J. G. Radziszewski J. Michl

1986-01-01

380

R-Symmetric Gauge Mediation and the Minimal R-Symmetric Supersymmetric Standard Model  

NASA Astrophysics Data System (ADS)

This is an invited summary of a seminar talk given at various institutions in the United States and Canada. After a brief introduction, a review of the minimal R-symmetric supersymmetric standard model is given, and the benefits to the flavor sector are discussed. R-symmetric gauge mediation is an attempt to realize this model using metastable supersymmetry breaking techniques. Sample low energy spectra are presented and tuning is discussed. Various other phenomenological results are summarized.

Blechman, Andrew E.

381

Higher density wavelet frames with symmetric low-pass and band-pass filters  

Microsoft Academic Search

This paper presents a new set of higher density wavelet frames with symmetric low-pass and band-pass wavelet filters. Based on the maximally flat low-pass linear-phase FIR filter and spectral factorization, two types of design approaches are proposed, which can respectively obtain odd-length FIR filters and even-length FIR filters. The two compact support wavelets respectively have a specified order of vanishing

Yi Qin; Jiaxu Wang; Baoping Tang; Yongfang Mao

2010-01-01

382

Quasi-steady symmetric regimes of a rotating annulus differentially heated on the horizontal boundaries  

NASA Astrophysics Data System (ADS)

The symmetric flows in a rotating annulus with horizontal boundaries maintained at temperatures as linear functions of radial distance, and with vertical boundaries thermally insulated are investigated for the infinitesimal Ekman number and the product of the Prandtl and thermal Rossby numbers ranging from infinitesimal to 0(10). The heat transfer is by conduction for the infinitesimal value of this product; vertical mass exchange is by Ekman suction through the interior.

Quon, C.

1980-11-01

383

NUMERICAL APPROXIMATION OF BLOW-UP OF RADIALLY SYMMETRIC SOLUTIONS OF THE NONLINEAR SCHR ¨ ODINGER EQUATION  

Microsoft Academic Search

We consider the initial-value problem for the radially symmetric nonlinear Schrodin- ger equation with cubic nonlinearity (NLS) in d = 2 and 3 space dimensions. To approximate smooth solutions of this problem, we construct and analyze a numerical method based on a standard Galerkin finite element spatial discretization with piecewise linear, continuous functions and on an implicit Crank-Nicolson type time-stepping

G. D. AKRIVIS; V. A. DOUGALIS; O. A. KARAKASHIAN; W. R. MCKINNEY

384

Facile synthesis and versatile topological transformation of mono-cleavable symmetric starlike terpolymers.  

PubMed

A straightforward strategy involving a RAFT process and ring-opening polymerization was used to construct symmetric reduction-responsive amphiphilic A(2m)B(2n)C(2) (m?n? 3) starlike terpolymers with precise microstructure, which could be efficiently converted into thiol-functionalized telechelic stars, degraded A(m)B(n)C miktoarm stars and comblike-linear multiblock copolymers via postmodification. PMID:22935725

Jiang, Xiao; Zhang, Meijing; Li, Shixian; Shao, Wei; Zhao, Youliang

2012-08-30

385

Phase space trajectories and quantization in PT-symmetric quantum mechanics  

NASA Astrophysics Data System (ADS)

For a fixed real energy, we prove that the classical turning points of a complex PT-symmetric potential occur as (z, -z*): either as (-a +ib, a + ib) or as ic. It is only in the former case that the potential possesses real discrete spectrum. The phase-space trajectories are closed and segregated in two parts: real (x, p real) and imaginary (x, p imag). The former are symmetric enclosing a finite area the latter are antisymmetric having null area. Nevertheless, the finite area accounts correctly for real discrete spectrum. We believe that with this, PT-symmetric quantum mechanics passes one of the most stringent tests towards a description that is consistent and compatible with conventional quantum mechanics.

Ahmed, Zafar

2005-09-01

386

Full and reduced model solutions of unsteady axi-symmetric ice sheet flow over a flat bed  

Microsoft Academic Search

A finite element algorithm is presented for the solution of the unsteady free-surface problem governed by the full, axi-symmetric, slow, linearly-viscous fluid flow equations for an isothermal ice sheet on a flat bed. A class of linearly viscous Reduced Model, Shallow Ice Approximation, exact solutions is also constructed, for which the relative error is of order of the very small

K. A. Cliffe; L. W. Morland

2004-01-01

387

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.

Roy, Kuntal; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

2013-01-01

388

Binary switching in a 'symmetric' potential landscape.  

PubMed

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

2013-10-24

389

PT-symmetric representations of fermionic algebras  

SciTech Connect

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

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

2011-08-15

390

Numerical Investigation of Symmetric and Asymmetric Periodic Oscillations  

Microsoft Academic Search

Global information for the periodic solutions --- symmetric and asymmetric --- of the `gravitational' spring-pendulum problem is given for the first time. For two different sets of the parameters of this problem, the families of symmetric periodic solutions which emanate from the equilibrium point have been determined. Further families of asymmetric and symmetric solutions which bifurcate from them have also

P. G. Kazantzis

1981-01-01

391

Symmetrically reduced Galileon equations and solutions  

NASA Astrophysics Data System (ADS)

The maximally complicated arbitrary-dimensional “maximal” Galileon field equations simplify dramatically for symmetric configurations. Thus, spherical symmetry reduces the equations from the D- to the two-dimensional (Monge-Ampere) equation, axial symmetry to its cubic extension, etc. We can then obtain explicit solutions, such as spherical or axial waves, and relate them to the (known) general, but highly implicit, lower-D solutions.

Deser, S.; Franklin, J.

2012-08-01

392

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

393

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

394

Cellular Programming and Symmetric Key Cryptography Systems  

Microsoft Academic Search

The problem of designing symmetric key cryptography algorithms based upon cellular automata (CAs) is considered. The reliability\\u000a of the Vernam cipher used in the process of encryption highly depends on a quality of used random numbers. One dimensional,\\u000a nonuniform CAs is considered as a generator of pseudorandom number sequences (PNSs). The quality of PNSs highly depends on\\u000a a set of

Franciszek Seredynski; Pascal Bouvry; Albert Y. Zomaya

2003-01-01

395

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

396

Tilted Cylindrically Symmetric Self-Similar Solutions  

NASA Astrophysics Data System (ADS)

This paper is devoted to explore tilted kinematic self-similar solutions of the the general cylindrical symmetric spacetimes. These solutions are of the first, zeroth, second and infinite kinds for the perfect fluid and dust cases. Three different equations of state are used to obtain these solutions. We obtain a total of five independent solutions. The correspondence of these solutions with those already available in the literature is also given.

Sharif, M.; Sultan, S.

2009-06-01

397

Asymmetric versus symmetric pulses for cortical microstimulation.  

PubMed

Intracortical microstimulation (ICMS), which has shown promise in the visual, auditory and somatosensory systems as a platform for sensory prostheses, typically relies on charged balanced, symmetric, biphasic stimulation. However, neural stimulation models as well as experiments conducted in cochlear implant users have suggested that charge balanced asymmetric pulses could generate lower detection thresholds for stimulation in terms of charge per phase. For this study, rats were chronically implanted with microelectrode arrays unilaterally in their right auditory cortex and then trained to detect ICMS delivered through a single electrode site in order to determine their behavioral threshold. This model was used in two experiments. The first experiment addressed the effect of lead phase direction, asymmetry, and phase duration on detection threshold. The second experiment fixed the cathode phase duration at 123 ?s and varied only the phase asymmetry and lead phase direction. Taken together, the results of these experiments suggest that, for ICMS, the primary determinant of threshold level is cathode phase duration, and that asymmetry provides no significant advantage when compared to symmetric, cathode leading pulses. However, symmetric anode leading pulses of less than or equal to 205 ?s per phase consistently showed higher thresholds when compared to all other pulses of equal cathode phase duration. PMID:21968793

Koivuniemi, Andrew S; Otto, Kevin J

2011-10-03

398

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

399

Electromagnetic scattering from skew-symmetric metallic grids  

NASA Astrophysics Data System (ADS)

In many applications for reflector antennas, the reflector is made from flexible, conducting material. The wires are weaved together, forming a very complex structure to study. So far, these mesh structures have been approximated by rectangular grids. In this study, the mesh geometry is approximated by a skew-symmetric grid. The FFT-conjugate gradient method (FFT-CGM) is employed to solve the problem of scattering from such grids. A convenient unit cell is chosen and utilized to study the effects of skewness on the reflection coefficients and current densities. Calculated values of the reflection coefficient for different angles of incidence for both the bonded and unbonded skewed gratings are presented and discussed.

Christodoulou, C. G.

1993-10-01

400

An antidynamo theorem for spherically symmetric generation-diffusion conditions  

NASA Astrophysics Data System (ADS)

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

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

401

Computed tomography of cylindrically symmetric object by use of digital holography  

NASA Astrophysics Data System (ADS)

Digital holographic tomography, a computed tomography by use of digital holography, has a huge potential for three-dimensional imaging of weakly-diffracting phase objects. But the need of multiple angles of illumination weakened imaging capability of dynamic objects. For cylindrically symmetric object, we can use complex amplitude data of single hologram under zero incidence angles to replace the other complex amplitude data under different incidence angles. Therefore, it is possible to achieve the dynamic imaging of cylindrically symmetric objects. The digital holographic tomography can provide a way for the dynamic imaging of phase-type objects having a cylindrically symmetric structure. We report an experimental example of the capillary tube having a cylindrically symmetric structure. Tomography of the capillary tube is performed by filtered back-projection algorithm and Fourier diffraction algorithm respectively to reconstruct the 3-D map of refractive index. Experimental results show that, comparing with the filtered back-projection reconstruction, diffraction tomography based on the Rytov approximation better respects the dimensions of the capillary tube.

Pan, Zhelang; Li, Shiping; Zhong, Jingang

2013-04-01

402

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

403

The Caenorhabditis elegans septin complex is nonpolar  

PubMed Central

Septins are conserved GTPases that form heteromultimeric complexes and assemble into filaments that play a critical role in cell division and polarity. Results from budding and fission yeast indicate that septin complexes form around a tetrameric core. However, the molecular structure of the core and its influence on the polarity of septin complexes and filaments is poorly defined. The septin complex of the nematode Caenorhabditis elegans is formed entirely by the core septins UNC-59 and UNC-61. We show that UNC-59 and UNC-61 form a dimer of coiled-coil-mediated heterodimers. By electron microscopy, this heterotetramer appears as a linear arrangement of four densities representing the four septin subunits. Fusion of GFP to the N termini of UNC-59 and UNC-61 and subsequent electron microscopic visualization suggests that the sequence of septin subunits is UNC-59/UNC-61/UNC-61/UNC-59. Visualization of GFP extensions fused to the extremity of the C-terminal coiled coils indicates that these extend laterally from the heterotetrameric core. Together, our study establishes that the septin core complex is symmetric, and suggests that septins form nonpolar filaments.

John, Corinne M; Hite, Richard K; Weirich, Christine S; Fitzgerald, Daniel J; Jawhari, Hatim; Faty, Mahamadou; Schlapfer, Dominik; Kroschewski, Ruth; Winkler, Fritz K; Walz, Tom; Barral, Yves; Steinmetz, Michel O

2007-01-01

404

A permanent magnet tubular linear generator for wave energy conversion  

NASA Astrophysics Data System (ADS)

A novel three-phase permanent magnet tubular linear generator (PMTLG) with Halbach array is proposed for the sea wave energy conversion. Non-linear axi-symmetrical finite element method (FEM) is implemented to calculate the magnetic fields along air-gap for different Halbach arrays of PMTLGs. The PMTLG characteristics are analyzed and the simulation results are validated by the experiment. An assistant tooth is implemented to greatly minimize the end and cogging effects which cause the oscillatory detent force.

Yu, Haitao; Liu, Chunyuan; Yuan, Bang; Hu, Minqiang; Huang, Lei; Zhou, Shigui

2012-04-01

405

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

2007-06-26

406

Characterisation of an AGATA symmetric prototype detector  

NASA Astrophysics Data System (ADS)

The Advanced GAmma Tracking Array (AGATA) symmetric prototype detector has been tested at the University of Liverpool. A 137Ce source, collimated to a 2 mm diameter, was scanned across the front face of the detector and data were acquired utilising digital electronics. Pulse shapes from a selection of well-defined photon interaction positions have been analysed to investigate the position sensitivity of the detector. Furthermore, the application of the electric field simulation software, Multi Geometry Simulation (MGS) to generate theoretical pulse shapes for AGATA detectors has been presented.

Nelson, L.; Dimmock, M. R.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Nolan, P. J.; Lazarus, I.; Simpson, J.; Medina, P.; Santos, C.; Parisel, C.

2007-04-01

407

Expanding symmetric multiprocessor capability through gang scheduling  

SciTech Connect

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

Jette, M.A.

1998-03-01

408

Design of spherical symmetric gradient index lenses  

NASA Astrophysics Data System (ADS)

Spherical symmetric refractive index distributions also known as Gradient Index lenses such as the Maxwell-Fish-Eye (MFE), the Luneburg or the Eaton lenses have always played an important role in Optics. The recent development of the technique called Transformation Optics has renewed the interest in these gradient index lenses. For instance, Perfect Imaging within the Wave Optics framework has recently been proved using the MFE distribution. We review here the design problem of these lenses, classify them in two groups (Luneburg moveable-limits and fixed-limits type), and establish a new design techniques for each type of problem.

Miñano, Juan C.; Grabovi?ki?, Dejan; Benítez, Pablo; González, Juan C.; Santamaría, Asunción

2012-10-01

409

Synthesis of symmetrical and nonsymmetrical bisthienylcyclopentenes.  

PubMed

Diarylethenes possess unique structural properties, which enabled them to find widespread applications in the field of photochromism. Nowadays, bisthienylcyclopentenes (BTCs) present the most popular subfamily of these compounds, which are widely used as P-type chromophores. This minireview summarises the main strategies for the synthesis of symmetrical and nonsymmetrical BTCs. In addition, attention is drawn to desymmetrisations achieved by monosubstitutions, which is not frequently utilised, although it can be highly advantageous. This is supported with some of the authors' latest results. PMID:23943569

Szalóki, György; Pozzo, Jean-Luc

2013-08-19

410

{PT} symmetric Hamiltonian model and Dirac equation in 1+1 dimensions  

NASA Astrophysics Data System (ADS)

In this paper, we have introduced a {PT} symmetric non-Hermitian Hamiltonian model which is given as \\hat{ {H}}=\\omega (\\hat{b}^{\\dag }\\hat{b}+\\frac{1}{2})+ \\alpha (\\hat{b}^{2}-(\\hat{b}^{\\dag })^{2}) where ? and ? are real constants, \\hat{b} and \\hat{b^{\\dag }} are first-order differential operators. The Hermitian form of the Hamiltonian {\\hat{ H}} is obtained by suitable mappings and it is interrelated to the time-independent one-dimensional Dirac equation in the presence of position-dependent mass. Then, Dirac equation is reduced to a Schrödinger-like equation and two new complex non- {PT} symmetric vector potentials are generated. We have obtained a real spectrum for these new complex vector potentials using the shape invariance method. We have searched the real energy values using numerical methods for the specific values of the parameters.

Ye?ilta?, Özlem

2013-01-01

411

The Tile Complexity of Linear Assemblies  

Microsoft Academic Search

Self-assembly is fundamental to both biological processes and nanoscience. Key features of self-assembly are its probabilistic nature and local programmability. These features can be leveraged to design better self-assembled systems. The conventional Tile Assembly Model (TAM) developed by Winfree using Wang tiles is a powerful, Turing-universal theoretical framework which models varied self-assembly processes. A particular challenge in DNA nanoscience is

Harish Chandran; Nikhil Gopalkrishnan; John H. Reif

2009-01-01

412

The Shroud around the `Compact, Symmetric' Radio Jets in NGC1052  

Microsoft Academic Search

This is a paper on young jet material in a frustratingly complex environment. NGC1052 has a compact, flat or GHz peaked spectrum radio nucleus consisting of bi-symmetric jets, oriented close to the plane of the sky. Many features on both sides move away at upsiloapp~0.26c (H0 = 65kms-1Mpc-1). VLBI at seven frequencies shows a wide range of spectral shapes and

R. C. Vermeulen; E. Ros; K. I. Kellermann; M. H. Cohen; J. A. Zensus; H. J. van Langevelde

2003-01-01

413

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

PubMed Central

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

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

2011-01-01

414

On adaptive EVD asymptotic distribution of centro-symmetric covariance matrices  

Microsoft Academic Search

This article investigates the gain in statistical performance\\/complexity of the adaptive estimation of the eigenvalue decomposition (EVD) of covariance matrices when the centro-symmetric (CS) structure of such matrices is utilized. After deriving the asymptotic distribution of the EVD estimators, it is shown, in particular, that the closed-form expressions for the asymptotic covariance of batch and adaptive EVD estimators are very

J.-P. Delmas

1999-01-01

415

BioClips of symmetric and asymmetric cell division.  

PubMed

Animations have long been used as tools to illustrate complex processes in such diverse fields as mechanical engineering, astronomy, bacteriology and physics. Animations in biology hold particular educational promise for depicting complex dynamic processes, such as photosynthesis, motility, viral replication and cellular respiration, which cannot be easily explained using static two-dimensional images. However, these animations have often been restrictive in scope, having been created for a specific classroom or research audience. In recent years, a new type of animation has emerged called the BioClip (http://www.bioclips.com) that strives to present science in an interactive multimedia format, which is, at once, informative and entertaining, by combining animations, text descriptions and music in one portable cross-platform document. In the present article, we illustrate the educational value of this new electronic resource by reviewing in depth two BioClips our group has created which describe the processes of symmetric and asymmetric cell division (http://www.wormclassroom.org/cb/bioclip). PMID:17437407

Lu, Fong-Mei; Eliceiri, Kevin W; White, John G

2007-05-01

416

Hermitian four-well potential as a realization of a PT-symmetric system  

NASA Astrophysics Data System (ADS)

A PT-symmetric Bose-Einstein condensate can be theoretically described using a complex optical potential; however, the experimental realization of such an optical potential describing the coherent in- and outcoupling of particles is a nontrivial task. We propose an experiment for a quantum mechanical realization of a PT-symmetric system, where the PT-symmetric currents of a two-well system are implemented by coupling two additional wells to the system, which act as particle reservoirs. In terms of a simple four-mode model we derive conditions under which the two middle wells of the Hermitian four-well system behave exactly as the two wells of the PT-symmetric system. We apply these conditions to calculate stationary solutions and oscillatory dynamics. By means of frozen Gaussian wave packets we relate the Gross-Pitaevskii equation to the four-mode model and give parameters required for the external potential, which provides approximate conditions for a realistic experimental setup.

Kreibich, Manuel; Main, Jörg; Cartarius, Holger; Wunner, Günter

2013-05-01

417

Operational multipartite entanglement classes for symmetric photonic qubit states  

SciTech Connect

We present experimental schemes that allow us to study the entanglement classes of all symmetric states in multiqubit photonic systems. We compare the efficiency of the proposed schemes and highlight the relation between the entanglement properties of symmetric Dicke states and a recently proposed entanglement scheme for atoms. In analogy to the latter, we obtain a one-to-one correspondence between well-defined sets of experimental parameters and multiqubit entanglement classes inside the symmetric subspace of the photonic system.

Kiesel, N.; Wieczorek, W.; Weinfurter, H. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Department fuer Physik, Ludwig-Maximilians-Universitaet, D-80797 Garching (Germany); Krins, S.; Bastin, T. [Institut de Physique Nucleaire, Atomique et de Spectroscopie, Universite de Liege, 4000 Liege (Belgium); Solano, E. [Departamento de Quimica Fisica, Universidad del Pais Vasco/Euskal Herriko Unibertsitatea, Apdo. 644, 48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, Alameda Urquijo 36, 48011 Bilbao (Spain)

2010-03-15

418

Fabrication Examples of Non-rotationally Symmetric Optical Elements  

Microsoft Academic Search

Two examples of a fabrication of non-rotationally symmetric optical elements are presented here, with a particular attention given to the techniques chosen for the process. Abrasive Grinding is mentioned briefly as the technique which originated many of the early applications of non-symmetric optics, followed by Fast Tool Servo turning and Diamond Milling. Metrology tools for non-symmetric optics, or lack thereof,

J. J. Mader; D. M. Combs; N. E. Claytor; O. M. Lechuga

419

Nonlinear coupling of tearing fluctuations in the Madison Symmetric Torus  

SciTech Connect

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

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

1992-11-01

420

Nonlinear coupling of tearing fluctuations in the Madison Symmetric Torus  

SciTech Connect

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

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

1992-11-01

421

Rectification in Symmetric Conjugated Molecules with Asymmetric Linkers  

NASA Astrophysics Data System (ADS)

Demonstrating single-molecule rectification is an important step towards the realization of molecule-based electronic devices. Most molecules put forward as potential rectifiers employ asymmetric molecular backbones. In contrast, we show that we can create rectifying junctions by designing asymmetry only into the linker groups used to bond the molecule to metal electrodes. Our molecules consist of a conjugated backbone terminated with methylsulfide on one end and methyl-trimethyltin on the other. These molecules couple to Au electrodes through an Au-SMe donor acceptor bond, which serves as the electronically weak link, and a Au-C covalent bond, which is created in-situ after the SnMe3 cleaves off [1]. We create thousands of molecular junctions using a modified STM setup in a solution of molecules, measure their current-voltage (IV) characteristics and create averaged IV curves. We find that asymmetrically terminated molecules show non-linear IV curves with significant rectification, while molecules terminated symmetrically with either SMe or SnMe3 do not show substantial rectification. We also find that the rectification direction is dependent on molecular orientation in the junction. [1] Chen, W., et al., J. Am. Chem. Soc., 2011. 133(43): p. 17160-17163

Batra, Arunabh; Meisner, Jeffrey S.; Widawsky, Jonathan R.; Huisman, Eek; Nuckolls, Colin; Venkataraman, Latha

2012-02-01

422

Symmetric and nonsymmetric Holmboe instabilities in an inviscid flow  

NASA Astrophysics Data System (ADS)

Using linear stability analysis we studied the effect of displacing a thin density interface with respect to the center of the shear layer on the stability of an inviscid, stably stratified, parallel flow. When no interface displacement is present and the flow is unbounded, pure Holmboe instabilities exist at all bulk Richardson numbers and are the most unstable instabilities for values of the bulk Richardson number greater than 0.046. When the interface displacement is nonzero the two modes of a Holmboe instability split into a stronger and a weaker mode. As the height of the vertical domain decreases the roles of the two modes switch with the originally weaker mode becoming the stronger mode and vice versa. The importance of including the height of the vertical domain in the stability analysis was illustrated by comparing theoretical results with the field data of Yoshida et al. [Yoshida, Ohtani, Nishida, and Linden, in Physical Processes in Lakes and Oceans, edited by J. Imberger (American Geophysical Union, Washington, DC, 1998), pp. 389-400]. The assumption that the instabilities are initially two-dimensional is examined. When the flow is unbounded, both symmetric and nonsymmetric Holmboe instabilities are initially two-dimensional. When boundaries are included, the two-dimensional assumption is valid except when the total vertical domain is small in which case three-dimensional primary instabilities are possible.

Haigh, S. P.; Lawrence, G. A.

1999-06-01

423

Stability for the spherically symmetric Einstein–Vlasov system–a coercivity estimate  

NASA Astrophysics Data System (ADS)

The stability of static solutions of the spherically symmetric, asymptotically flat Einstein-Vlasov system is studied using a Hamiltonian approach based on energy-Casimir functionals. The main result is a coercivity estimate for the quadratic part of the expansion of the natural energy-Casimir functional about an isotropic steady state. The estimate shows in a quantified way that this quadratic part is positive definite on a class of linearly dynamically accessible perturbations, provided the particle distribution of the steady state is a strictly decreasing function of the particle energy and provided the steady state is not too relativistic. This should be an essential step in a fully non-linear stability analysis for the Einstein-Vlasov system. In the present paper it is exploited for obtaining a linearized stability result.

Hadži?, Mahir; Rein, Gerhard

2013-11-01

424

Symmetric instability in the Gulf Stream  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

425

Covariant approach for perturbations of rotationally symmetric spacetimes  

SciTech Connect

We present a covariant decomposition of Einstein's field equations which is particularly suitable for perturbations of spherically symmetric - and general locally rotationally symmetric - spacetimes. Based upon the utility of the 1+3 covariant approach to perturbation theory in cosmology, the semi-tetrad, 1+1+2 approach presented here should be useful for analyzing perturbations of a variety of systems in a covariant and gauge-invariant manner. Such applications range from stellar objects to cosmological models such as the spherically symmetric Lemaitre-Tolman-Bondi solutions or the class of locally rotationally symmetric Bianchi models.

Clarkson, Chris [Cosmology and Gravity Group, Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa)

2007-11-15

426

Multiprocessing linear algebra algorithms on the CRAY X-MP-2: Experiences with small granularity  

Microsoft Academic Search

This paper gives a brief overview of the CRAY X-MP-2 general-purpose multiprocessor system and discusses how it can be used effectively to solve problems that have small granularity. An implementation is described for linear algebra algorithms that solve systems of linear equations when the matrix is general and when the matrix is symmetric and positive definite.

STEVEN S. CHEN; J. J. Dongarra; CHRISTOPHER C. HSIUNG

1984-01-01

427

A posteriori finite element bounds for linear-functional outputs of elliptic partial differential equations  

Microsoft Academic Search

We present a domain decomposition finite element technique for efficiently generating lower and upper bounds to outputs which are linear functionals of the solutions to symmetric or nonsymmetric second-order coercive linear partial differential equations in two space dimensions. The method is based upon the construction of an augmented Lagrangian, in which the objective is a quadratic ‘energy’ reformulation of the

Marius Paraschivoiu; Jaime Peraire; Anthony T. Patera

1997-01-01

428

Geometric inequalities for axially symmetric black holes  

NASA Astrophysics Data System (ADS)

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

Dain, Sergio

2012-04-01

429

Lovelock black holes with maximally symmetric horizons  

NASA Astrophysics Data System (ADS)

We investigate some properties of n( >= 4)-dimensional spacetimes having symmetries corresponding to the isometries of an (n - 2)-dimensional maximally symmetric space in Lovelock gravity under the null or dominant energy condition. The well-posedness of the generalized Misner-Sharp quasi-local mass proposed in the past study is shown. Using this quasi-local mass, we clarify the basic properties of the dynamical black holes defined by a future outer trapping horizon under certain assumptions on the Lovelock coupling constants. The C2 vacuum solutions are classified into four types: (i) Schwarzschild-Tangherlini-type solution; (ii) Nariai-type solution; (iii) special degenerate vacuum solution; and (iv) exceptional vacuum solution. The conditions for the realization of the last two solutions are clarified. The Schwarzschild-Tangherlini-type solution is studied in detail. We prove the first law of black-hole thermodynamics and present the expressions for the heat capacity and the free energy.

Maeda, Hideki; Willison, Steven; Ray, Sourya

2011-08-01

430

Horseshoes for the nearly symmetric heavy top  

NASA Astrophysics Data System (ADS)

We prove the existence of horseshoes in the nearly symmetric heavy top. This problem was previously addressed but treated inappropriately due to a singularity of the equations of motion. We introduce an (artificial) inclined plane to remove this singularity and use a Melnikov-type approach to show that there exist transverse homoclinic orbits to periodic orbits on four-dimensional level sets. The price we pay for removing the singularity is that the Hamiltonian system becomes a three-degree-of-freedom system with an additional first integral, unlike the two-degree-of-freedom formulation in the classical treatment. We therefore have to analyze three-dimensional stable and unstable manifolds of periodic orbits in a six-dimensional phase space. A new Melnikov-type technique is developed for this situation. Numerical evidence for the existence of transverse homoclinic orbits on a four-dimensional level set is also given.

van der Heijden, G. H. M.; Yagasaki, Kazuyuki

2013-05-01

431

Scaling model for symmetric star polymers  

NASA Astrophysics Data System (ADS)

Neutron scattering data from symmetric star polymers with six poly (urethane-ether) arms, chemically bonded to a C-60 molecule are fitted using a new scaling model and scattering function. The new scaling function can describe both good solvent and theta solvent conditions as well as resolve deviations in chain conformation due to steric interactions between star arms. The scaling model quantifies the distinction between invariant topological features for this star polymer and chain tortuosity which changes with goodness of solvent and steric interaction. Beaucage G, Phys. Rev. E 70 031401 (2004).; Ramachandran R, et al. Macromolecules 41 9802-9806 (2008).; Ramachandran R, et al. Macromolecules, 42 4746-4750 (2009); Rai DK et al. Europhys. Lett., (Submitted 10/2009).

Ramachandran, Ram; Rai, Durgesh K.; Beaucage, Gregory

2010-03-01

432

From symmetric glycerol derivatives to dissymmetric chlorohydrins.  

PubMed

The anticipated worldwide increase in biodiesel production will result in an accumulation of glycerol for which there are insufficient conventional uses. The surplus of this by-product has increased rapidly during the last decade, prompting a search for new glycerol applications. We describe here the synthesis of dissymmetric chlorohydrin esters from symmetric 1,3-dichloro-2-propyl esters obtained from glycerol. We studied the influence of two solvents: 1,4-dioxane and 1-butanol and two bases: sodium carbonate and 1-butylimidazole, on the synthesis of dissymmetric chlorohydrin esters. In addition, we studied the influence of other bases (potassium and lithium carbonates) in the reaction using 1,4-dioxane as the solvent. The highest yield was obtained using 1,4-dioxane and sodium carbonate. PMID:21368718

Solarte, Carmen; Escribà, Marc; Eras, Jordi; Villorbina, Gemma; Canela, Ramon; Balcells, Mercè

2011-03-02

433

mathcal{CPT}-Symmetric Discrete Square Well  

NASA Astrophysics Data System (ADS)

In an addendum to the recent systematic Hermitization of certain N by N matrix Hamiltonians H ( N)( ?) (Znojil in J. Math. Phys. 50:122105, 2009) we propose an amendment H ( N)( ?, ?) of the model. The gain is threefold. Firstly, the updated model acquires a natural mathematical meaning of Runge-Kutta approximant to a differential mathcal{PT}-symmetric square well in which mathcal{P} is parity. Secondly, the appeal of the model in physics is enhanced since the related operator mathcal{C} of the so called "charge" (the requirement of observability of which defines the most popular Bender's metric ?=mathcal{PC}) becomes also obtainable (and is constructed here) in an elementary antidiagonal matrix form at all N. Last but not least, the original phenomenological energy spectrum is not changed so that the domain of its reality (i.e., the interval of admissible couplings ??(-1,1)) remains the same.

Znojil, Miloslav; Tater, Miloš

2011-04-01

434

Circularly symmetric light scattering from nanoplasmonic spirals.  

PubMed

In this paper, we combine experimental dark-field imaging, scattering, and fluorescence spectroscopy with rigorous electrodynamics calculations in order to investigate light scattering from planar arrays of Au nanoparticles arranged in aperiodic spirals with diffuse, circularly symmetric Fourier space. In particular, by studying the three main types of Vogel's spirals fabricated by electron-beam lithography on quartz substrates, we demonstrate polarization-insensitive planar light diffraction in the visible spectral range. Moreover, by combining dark-field imaging with analytical multiparticle calculations in the framework of the generalized Mie theory, we show that plasmonic spirals support distinctive structural resonances with circular symmetry carrying orbital angular momentum. The engineering of light scattering phenomena in deterministic structures with circular Fourier space provides a novel strategy for the realization of optical devices that fully leverage on enhanced, polarization-insensitive light-matter coupling over planar surfaces, such as thin-film plasmonic solar cells, plasmonic polarization devices, and optical biosensors. PMID:21466155

Trevino, Jacob; Cao, Hui; Dal Negro, Luca

2011-04-05

435

VACUUM calculation in azimuthally symmetric geometry  

SciTech Connect

A robustly accurate and effective method is presented to solve Laplace`s equation in general azimuthally symmetric geometry for the magnetic scalar potential in the region surrounding a plasma discharge which may or may not contain external conducting shells. These shells can be topologically toroidal or spherical, and may have toroidal gaps in them. The solution is incorporated into the various MHD stability codes either through the volume integrated perturbed magnetic energy in the vacuum region or through the continuity requirements for the normal component of the perturbed magnetic field and the total perturbed pressure across the unperturbed plasma-vacuum boundary. The method is based upon using Green`s second identity and the method of collocation. As useful byproducts, the eddy currents and the simulation of Mirnov loop measurements are calculated.

Chance, M.S.

1996-11-01

436

Nonlinear dynamics in PT-symmetric lattices  

NASA Astrophysics Data System (ADS)

We consider nonlinear dynamics in a finite parity-time-symmetric chain of the discrete nonlinear Schrödinger (dNLS) type. For arbitrary values of the gain and loss parameter, we prove that the solutions of the dNLS equation do not blow up in a finite time but nevertheless, there exist trajectories starting with large initial data that grow exponentially fast for larger times with a rate that is rigorously identified. In the range of the gain and loss parameter, where the zero equilibrium state is neutrally stable, we prove that the trajectories starting with small initial data remain bounded for all times. Numerical computations illustrate these analytical results for dimers and quadrimers.

Kevrekidis, Panayotis G.; Pelinovsky, Dmitry E.; Y Tyugin, Dmitry

2013-09-01

437

New non-symmetrical choline kinase inhibitors.  

PubMed

Identification of novel and selective anticancer agents remains an important and challenging goal in pharmacological research. Choline kinase (ChoK) is the first enzyme in the CDP-choline pathway that synthesizes phosphatidylcholine (PC), the major phospholipid in eukaryotic cell membranes. In the present paper, a new family of non-symmetrical monocationic compounds is developed including a 3-aminophenol moiety, bound to 4-(dimethylamino)- or 4-(pyrrolidin-1-yl)pyridinium cationic heads through several linkers. The most promising compounds in these series as ChoK inhibitors are 3f and 4f, while compounds 3c, 3d and 4c are the better antiproliferative agents. The analysis of the biological data observed in the described series of compounds mays represents a platform for the design of more active molecules. PMID:24080101

Schiaffino-Ortega, Santiago; López-Cara, Luisa Carlota; Ríos-Marco, Pablo; Carrasco-Jimenez, Maria Paz; Gallo, Miguel A; Espinosa, Antonio; Marco, Carmen; Entrena, Antonio

2013-09-11

438

Symmetric Lipofibromatous Hamartoma Affecting Digital Nerves  

PubMed Central

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

Jung, Sung-No; Yim, Youngmin

2005-01-01

439

The complex pendulum  

SciTech Connect

In this talk we propose to broaden the conventional notion of quantum mechanics. In conventional quantum mechanics one imposes the condition H{sup {dagger}}=H, where {dagger} represents complex conjugation and matrix transpose, to ensure that the Hamiltonian has a real spectrum. Replacing this mathematical condition by the weaker and more physical requirement H{sup {double_dagger}}=H, where {double_dagger}=PT represents combined parity reflection and time reversal, one obtains new infinite classes of complex Hamiltonians whose spectra are also real and positive. These PT-symmetric theories may be viewed as analytic continuations of conventional theories from real to complex phase space. This talk describes the unusual classical and quantum properties of PT-symmetric quantum mechanical and quantum field theoretic models. {copyright} {ital 1998 American Institute of Physics.}

Bender, C.M. [Department of Physics, Washington University, St. Louis, Missouri 63130 (United States)

1998-12-01

440

The complex pendulum  

SciTech Connect

In this talk we propose to broaden the conventional notion of quantum mechanics. In conventional quantum mechanics one imposes the condition H{sup {dagger}}=H, where {dagger} represents complex conjugation and matrix transpose, to ensure that the Hamiltonian has a real spectrum. Replacing this mathematical condition by the weaker and more physical requirement H{sup {dagger}}=H, where {dagger}=PT represents combined parity reflection and time reversal, one obtains new infinite classes of complex Hamiltonians whose spectra are also real and positive. These PT-symmetric theories may be viewed as analytic continuations of conventional theories from real to complex phase space. This talk describes the unusual classical and quantum properties of PT-symmetric quantum mechanical and quantum field theoretic models.

Bender, Carl M. [Department of Physics, Washington University, St. Louis, Missouri 63130 (United States)

1998-12-15

441

Uranyl sequestering agents: Correlation of properties and efficacy with structure for UO{sub 2}{sup 2+} complexes of linear tetradentate 1-methyl-3-hydroxy-2(1H)-pyridinone ligands  

SciTech Connect

A rational design of uranyl sequestering agents based on 3-hydroxy-2(1H)-pyridinone ligands has resulted in the first effective agents for mammalian uranyl decorporation. In this study crystal structures of uranyl complexes with four of these agents are compared and correlated with the chemical and biological properties. These hydroxypyridinone ligands bind the uranyl ion in the equator of a pentagonal prism; a solvent molecule fills the fifth coordination site. The tetradentate ligands are composed of two hydroxypyridonate groups connected by a diamine linker via amide coupling. The dihedral angles between two pyridinone ring planes in these complexes differ as the length of linear backbone changes, giving these molecules a ruffled shape. The physical parameters (such as NMR chemical shifts) of the uranyl complexes with tetradentate Me-3,2-HOPO ligands correlate with the length of the diamine linker, as does the in vivo activity. The ligands are amides of 3-hydroxy-N-methyl-2-(1H)-4-carboxypyridone. For L{sup 1} the amine is propane amine. For the tetradentate bis-amides the linker groups are (L{sup 3}) 1,3-diaminopropane, (L{sup 4}) 1,4-diaminobutane, (L{sup 5}) 1,5-diaminopentane. Crystal data: [UO{sub 2}(L{sup 1}){sub 2}{center_dot}DMF], space group, C2/c, cell constants: a = 37.430(8) {angstrom}, b = 7.0808(14) {angstrom}, c = 26.781(5) {angstrom}, {beta} = 130.17(3){degree}, V = 5424(2) {angstrom}{sup 3}, Z = 8. [UO{sub 2}L{sup 3}{center_dot}DMSO], Pnma, a = 8.4113(1) {angstrom}, b = 16.0140(3) {angstrom}, c = 16.7339(3) {angstrom}, V = 2254.03(5) {angstrom}{sup 3}, Z = 4. [UO{sub 2}L{sup 4}{center_dot}DMSO]{center_dot}DMSO{center_dot}H{sub 2}O{center_dot}0.5C{sub 6}H{sub 12}, P2{sub 1}/n, a = 26.7382(4) {angstrom}, b = 7.4472(1) {angstrom}, c = 31.4876(2) {angstrom}, V = 6209.05(13) {angstrom}{sup 3}, Z = 8. [UO{sub 2}L{sup 5}{center_dot}DMSO]{center_dot}DMSO, Pnma, a = 7.3808(1) {angstrom}, b = 14.7403(3) {angstrom}, c = 23.134(3) {angstrom}, V = 2516.88(8) {angstrom}{sup 3}, Z = 4.

Xu, J. Raymond, K.N. [Lawrence Berkeley National Lab., CA (United States)

1999-01-25

442

On the existence of antisymmetric or symmetric Lamb waves at non-linear higher harmonics  

Microsoft Academic Search

This article theoretically studies the symmetry characteristics of Rayleigh-Lamb guided waves in nonlinear, isotropic plates. It has been known that the nonlinearity driven double harmonic in Lamb waves does not support antisymmetric motion. However the proof of this has not been obvious. Moreover, little is known on nonlinearity driven Lamb harmonics higher than double. These gaps were here studied by

A. Srivastava; F. Lanza di Scalea

2009-01-01

443

Linear polyubiquitin chains  

PubMed Central

The ubiquitin conjugation system regulates a wide variety of biological phenomena, including protein degradation and signal transduction, by regulating protein function via polyubiquitin conjugation in most cases. Several types of polyubiquitin chains exist in cells, and the type of polyubiquitin chain conjugated to a protein seems to determine how that protein is regulated. We identified a novel linear polyubiquitin chain and the ubiquitin-protein ligase complex that assembles it, designated LUBAC. Both were shown to have crucial roles in the canonical NF?B activation pathway. This year, three groups, including our laboratory, identified SHARPIN as a new subunit of LUBAC. Of great interest, Sharpin was identified as a causative gene of chronic proliferative dermatitis in mice (cpdm), which is characterized by numerous inflammatory symptoms including chronic dermatitis, arthritis and immune disorders. Deletion of SHARPIN drastically reduces the amount of LUBAC and attenuates signal-induced NF?B activation. The pleomorphic symptoms of cpdm mice suggest that LUBAC-mediated NF?B activation may play critical roles in mammals and be involved in various disorders. A forward look into the linear polyubiquitin research is also discussed.

2011-01-01

444

Synthesis and Physical Properties of Symmetrical and Non-symmetrical Triacylglycerols Containing Two Palmitic Fatty Acids  

Microsoft Academic Search

A series of symmetrical (ABA) and non-symmetrical (AAB) triacylglycerol (TAG) isomers containing “A,” palmitic (P; 16:0) acid,\\u000a and “B,” either oleic (O; 9c-18:1), elaidic (E; 9t-18:1), linoleic (L; 9c,12c-18:2) or linolenic (Ln; 9c,12c,15c-18:3) fatty\\u000a acids were synthesized by esterification of the thermodynamically more-stable 1,3-di- or 1(3)-monoacylglycerols [1,3-DAG or\\u000a 1(3)-MAG], respectively. 1,3-dipalmitoylglycerol (1,3P-DAG) was esterified with O, L or Ln acid

R. O. Adlof; G. R. List

2008-01-01

445

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

PubMed

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

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

2012-10-09

446

Linear sigma models with torsion  

NASA Astrophysics Data System (ADS)

Gauged linear sigma models with (0, 2) supersymmetry allow a larger choice of couplings than models with (2, 2) supersymmetry. We use this freedom to find a fully linear construction of torsional heterotic compactifications, including models with branes. As a non-compact example, we describe a family of metrics which correspond to deformations of the heterotic conifold by turning on H-flux. We then describe compact models which are gauge-invariant only at the quantum level. Our construction gives a generalization of symplectic reduction. The resulting spaces are non-Kähler analogues of familiar toric spaces like complex projective space. Perturbatively conformal models can be constructed by considering intersections.

Quigley, Callum; Sethi, Savdeep

2011-11-01

447

Spherically symmetric model atmospheres for late-type giant stars  

NASA Astrophysics Data System (ADS)

The ATHENA computer code was developed to model the extended atmospheres of late-type giant and supergiant stars. The atmospheres are assumed to be static, spherically symmetric and in radiative and hydrostatic equilibrium. Molecular line blanketing (for now) is handled using the simplifying assumption of mean opacity. The complete linearization method of Auer and Mihalas, adapted to spherical geometry, is used to solve the model system. The radiative transfer is solved by using variable Eddington factors to close the system of moment transfer equations, and the entire system of transfer equations plus constraints is solved efficiently by arrangement into the Rybicki block matrix form. The variable Eddington factors are calculated from the full angle-dependent formal solution of the radiative transfer problem using the impact parameter method of Hummer, Kunas. We were guided by the work of Mihalas and Hummer in their development of extended models of O stars, but our method differs in the choice of the independent variable. The radius depth scale used by Mihals and Hummer was found to fail because of the strongly temperature-dependent opacities of late-type atmospheres. Instead, we were able to achieve an exact linearization of the radius. This permitted the use of the numerically well-behaved column mass or optical depth scales. The resulting formulation is analogous to the plane-parallel complete linearization method and reduces to this method in the compact atmosphere limit. Models of M giants were calculated for Teff = 3000K and 3500K with opacities of the CN, TiO, and H2O molecules included, and the results were in general agreement with other published spherical models. These models were calculated assuming radiative equilibrium. The importance of convective energy transport was estimated by calculating the convective flux that would result from the temperature structure of the models. The standard local mixing length theory was used for this purpose. Convection was found to be important only at depths with tauRM greater than 15 for the low gravity models with log g = O, but significant out to tauRM is approximately 1 at the most transparent frequencies for the higher gravity models with log g = 2. Thus, the temperature structure of the surface layers and the emergent flux for the log g = O models should be accurately modelled but the emergent flux for the log g = 2 models may be in error by up to 5 percent at the most transparent frequencies.

Bennett, Philip Desmond

448

SIMULATION OF STRAIN INDUCED INTERFACE MIGRATION IN SYMMETRIC TILT GRAIN BOUNDARIES  

SciTech Connect

Grain boundary migration of flat symmetric tilt grain boundaries is simulated using molecular dynamics. The driving force for migration is achieved by applying uniaxial strain on one of the grains in the bicrystal, enabling the growth of strain free grain at the expense of strained grain. Arrhenius dependence of grain boundary mobility on temperature and a linear relation between mobility and grain boundary velocity are observed. Simulations suggest that the mechanism of migration is dependent on vacancy diffusion combined with local reshuffling of atoms near the grain boundary.

Namilae, Sirish [ORNL; Radhakrishnan, Balasubramaniam [ORNL; Gorti, Sarma B [ORNL

2007-01-01

449

The electrostatic potential of a two-layer three-element symmetric array  

NASA Astrophysics Data System (ADS)

The focusing of charged-particle beams by periodic electrostatic fields in such devices as linear accelerators and microwave oscillators can be carried out using a set of electrostatic lenses. An analysis is presented of the spatial distribution of electrostatic potential in this type of system in the form of a two-layer three-element symmetric array. The solution to the boundary value problem for the Laplace equation in the rigorous formulation is obtained by the method of the Riemann-Hilbert problem. The results are presented in the form of equipotential and force lines of the electric field.

Litvinenko, L. N.; Pogarskii, S. A.; Saprykin, I. I.; Sedykh, V. M.

450

The N-widths of spaces of holomorphic functions on bounded symmetric domains, II  

NASA Astrophysics Data System (ADS)

Let D be a bounded symmetric domain and [Sigma] be the Shilov boundary of D. For [lambda][set membership, variant]W, the Wallach set, and a nonnegative integer l, we study the weighted Bergman space A[lambda]2(D) and the weighted Bergman-Sobolev space A2,[lambda],l(D). For 0<[rho]<1 we obtain exact values of the Gel'fand and linear N-widths of A2,[lambda],l(D) in C([rho][Sigma]). We also obtain the Bernstein N-widths of the Hardy-Sobolev space H[infinity],l(D) in A[lambda]2([rho]D).

Ding, Hongming

2002-07-01

451

REVIEW The Use and Misuse of Conditional Symmetric Instability  

Microsoft Academic Search

A commonly employed explanation for single- and multiple-banded clouds and precipitation in the extratropics is slantwise convection due to the release of moist symmetric instability (MSI), of which one type is conditional symmetric instability (CSI). This article presents a review of CSI with the intent of synthesizing the results from previous observational, theoretical, and modeling studies. This review contends that

DAVID M. SCHULTZ; PHILIP N. SCHUMACHER

452

Constraints on the uncertainties of entangled symmetric qubits  

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

453

Lipoblastomatosis appearing as an unusual symmetric upper lip deformity.  

PubMed

We report an unusual case of a bilateral, symmetric upper lip deformity. The submucosal tissue of the resected redundant portion of the lip was occupied by a mass that was diagnosed histopathologically as lipoblastomatosis. Differential diagnoses of lesions with symmetric upper lip deformity and current controversy regarding the surgical treatment are discussed here. PMID:21784719

Morioka, Daichi; Amikura, Yoshiyasu

2011-07-23

454

Vacuum spherically symmetric solutions in f( T) gravity  

NASA Astrophysics Data System (ADS)

Spherically symmetric static vacuum solutions have been built in f( T) models of gravity theory. We apply some conditions on the metric components; then new vacuum spherically symmetric solutions are obtained. Also, by extracting metric coefficients we determine the analytical form of f( T).

Atazadeh, K.; Mousavi, Misha

2013-01-01

455

Minimum-error discrimination between symmetric mixed quantum states  

SciTech Connect

We provide a solution of finding optimal measurement strategy for distinguishing between symmetric mixed quantum states. It is assumed that the matrix elements of at least one of the symmetric quantum states are all real and non-negative in the basis of the eigenstates of the symmetry operator.

Chou, C.-L. [Department of Physics, Chung-Yuan Christian University, Taoyuan 32023, Taiwan (China); Hsu, L.Y. [Physics Division, National Center of Theoretical Science, Hsinchu 30055, Taiwan (China)

2003-10-01

456

Symmetric profile beams from waveguides with asymmetric grating couplers.  

PubMed

An accurate method to analyze integrated optics waveguides with a grating is used to design diffractive gratings. A novel approach to produce symmetric diffracted beams is proposed. In this approach, we vary the grating duty cycle along the propagation direction. We demonstrate that this method results in symmetrical diffracted beam profiles. PMID:18253245

Touam, T; Najafi, S I

1997-04-20

457

Generalized Symmetric Nonextensive Thermostatistics and q-MODIFIED Structures  

NASA Astrophysics Data System (ADS)

We formulate a convenient generalization of the q-expectation value, based on the analogy of the symmetric quantum groups and q-calculus, and show that the q? q-1 symmetric nonextensive entropy preserves all of the mathematical structure of thermodynamics just as in the case of nonsymmetric. Tsallis statistics. Basic propreties and analogies with quantum groups are discussed.

Lavagno, A.; Swamy, P. Narayana

458

Parity-Based Concurrent Error Detection in Symmetric Block Ciphers  

Microsoft Academic Search

Deliberate injection of faults into cryptographic devices is an effective cryptanalysis technique against symmetric and asymmetric encryption. We will describe a general concurrent error detection (CED) approach against such attacks on symmetric block ciphers using CS-cipher as an example. The proposed CED compares a carefully modified parity of the input plain text with that of the output cipher text. An

Ramesh Karri; Grigori Kuznetsov; Michael Goessel

2003-01-01

459

Stability of Trilateral Forces: II, Large Symmetric Force  

SciTech Connect

For large symmetric offensive forces, as for small, at few weapons per missile all forces are reserved, costs are constant, and configurations are stable. At many weapons permissile, no weapons are reserved, first strike costs decrease, fractionation is attractive, and stability degrades. These results a due to symmetries that would not be degraded by additional symmetric opponents.

Canavan, G.H.

1998-09-17

460

Directed cyclic Hamiltonian cycle systems of the complete symmetric digraph  

Microsoft Academic Search

In this paper, we prove that directed cyclic hamiltonian cycle systems of the complete symmetric digraph, K n, exist if and only if n 2 (mod4) and n 6= 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-independent digons, (Kn I) , exist

Heather Jordon; Joy Morris

2009-01-01