The finite scaling for S = 1 XXZ chains with uniaxial single-ion-type anisotropy

NASA Astrophysics Data System (ADS)

Wang, Honglei; Xiong, Xingliang

2014-03-01

The scaling behavior of criticality for spin-1 XXZ chains with uniaxial single-ion-type anisotropy is investigated by employing the infinite matrix product state representation with the infinite time evolving block decimation method. At criticality, the accuracy of the ground state of a system is limited by the truncation dimension χ of the local Hilbert space. We present four evidences for the scaling of the entanglement entropy, the largest eigenvalue of the Schmidt decomposition, the correlation length, and the connection between the actual correlation length ξ and the energy. The result shows that the finite scalings are governed by the central charge of the critical system. Also, it demonstrates that the infinite time evolving block decimation algorithm by the infinite matrix product state representation can be a quite accurate method to simulate the critical properties at criticality.

8-Hy­droxy­quinolin-1-ium hydrogen sulfate monohydrate

PubMed Central

Damous, Maamar; Dénès, George; Bouacida, Sofiane; Hamlaoui, Meriem; Merazig, Hocine; Daran, Jean-Claude

2013-01-01

In the crystal structure of the title salt hydrate, C9H8NO+·HSO4 −·H2O, the quinoline N—H atoms are hydrogen bonded to the bis­ulfate anions. The bis­ulfate anions and water mol­ecules are linked together by O—H⋯O hydrogen-bonding inter­actions. The cations and anions form separate layers alternating along the c axis, which are linked by N—H⋯O and O—H⋯O hydrogen bonds into a two-dimensional network parallel to (100). Further O—H⋯O contacts connect these layers, forming a three-dimensional network, in which two R 4 4(12) rings and C 2 2(13) infinite chains can be identified. PMID:24427083

Gacs quantum algorithmic entropy in infinite dimensional Hilbert spaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benatti, Fabio, E-mail: benatti@ts.infn.it; Oskouei, Samad Khabbazi, E-mail: kh.oskuei@ut.ac.ir; Deh Abad, Ahmad Shafiei, E-mail: shafiei@khayam.ut.ac.ir

We extend the notion of Gacs quantum algorithmic entropy, originally formulated for finitely many qubits, to infinite dimensional quantum spin chains and investigate the relation of this extension with two quantum dynamical entropies that have been proposed in recent years.

Entangled state teleportation through a couple of quantum channels composed of XXZ dimers in an Ising- XXZ diamond chain

NASA Astrophysics Data System (ADS)

Rojas, M.; de Souza, S. M.; Rojas, Onofre

2017-02-01

The quantum teleportation plays an important role in quantum information process, in this sense, the quantum entanglement properties involving an infinite chain structure is quite remarkable because real materials could be well represented by an infinite chain. We study the teleportation of an entangled state through a couple of quantum channels, composed by Heisenberg dimers in an infinite Ising-Heisenberg diamond chain, the couple of chains are considered sufficiently far away from each other to be ignored the any interaction between them. To teleporting a couple of qubits through the quantum channel, we need to find the average density operator for Heisenberg spin dimers, which will be used as quantum channels. Assuming the input state as a pure state, we can apply the concept of fidelity as a useful measurement of teleportation performance of a quantum channel. Using the standard teleportation protocol, we have derived an analytical expression for the output concurrence, fidelity, and average fidelity. We study in detail the effects of coupling parameters, external magnetic field and temperature dependence of quantum teleportation. Finally, we explore the relations between entanglement of the quantum channel, the output entanglement and the average fidelity of the system. Through a kind of phase diagram as a function of Ising-Heisenberg diamond chain model parameters, we illustrate where the quantum teleportation will succeed and a region where the quantum teleportation could fail.

Synthesis and crystal structure of novel fluorescent 1,3,4-oxadiazole-containing carboxylate ligands

NASA Astrophysics Data System (ADS)

Mikhailov, Igor E.; Popov, Leonid D.; Tkachev, Valery V.; Aldoshin, Sergey M.; Dushenko, Galina A.; Revinskii, Yurii V.; Minkin, Vladimir I.

2018-04-01

Novel chelating ligands, 3-(5-aryl-1,3,4-oxadiazol-2-yl)acrylic acids and their zinc complexes were synthesized and their spectral and luminescent properties studied. The compounds intensively (quantum efficiencies φ = 0.18-0.76) luminesce in nonpolar solvents in the blue-green region (λmaxPL = 458-504 nm) of the spectrum. Molecular and crystal structures of 3-[5-(4-dimethylaminophenyl)-1,3,4-oxadiazol-2-yl]acrylic acid were established using X-ray crystallography. In crystal, the infinite chains of the molecules lie in the parallel planes and are arranged by the "head to tail" type to provide for strong π-π stacking interactions between the layers facilitating appearance of high electron transport properties and formation of excimers.

Synthesis, crystal structure, and electrical and magnetic properties of BaMo{sub 6}Te{sub 6}: A novel reduced molybdenum telluride containing infinite chains of trans-face shared Mo{sub 6} octahedra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gall, Philippe; Guizouarn, Thierry; Potel, Michel

Powder samples and single crystals of the new ternary compound BaMo{sub 6}Te{sub 6} were obtained by solid state reaction. The structure was determined by single-crystal X-ray diffraction. BaMo{sub 6}Te{sub 6} crystallizes in the hexagonal space group P6{sub 3}/m (No. 176) with unit-cell parameters a=9.3941(2) Å, c=4.5848(1) Å and Z=1. Full-matrix least-squares refinement on F{sup 2} using 452 independent reflections for 17 refinable parameters resulted in R1=0.0208 and wR2=0.0539. The structure consists of one-dimensional infinite chains of trans-face shared Mo{sub 6} octahedra capped by Se atoms. These chains that are running along the c axis are separated from each other bymore » nine-coordinate Ba atoms. Resistivity measurements on a single crystal indicated that the BaMo{sub 6}Te{sub 6} compound is metallic down to 160 K and semiconductor below. Magnetic susceptibility measurements showed that BaMo{sub 6}Te{sub 6} is weakly diamagnetic with no anomaly at the metal–semiconductor transition. - Graphical abstract: We present here the synthesis, the crystal structure, and the electrical and magnetic properties of the new compound BaMo{sub 6}Te{sub 6} containing infinite chains of trans-face shared Mo{sub 6} octahedra. - Highlights: • BaMo{sub 6}Te{sub 6} contains infinite chains of trans-face-sharing Mo{sub 6} octahedra |Mo{sub 6/2}|{sub ∞}{sup 1}. • Synthesis by solid state reaction. • Single-crystal X-ray study. • Continuous metal–nonmetal transition. • Anderson localization.« less

Infinite number of solvable generalizations of XY-chain, with cluster state, and with central charge c = m/2

NASA Astrophysics Data System (ADS)

Minami, Kazuhiko

2017-12-01

An infinite number of spin chains are solved and it is derived that the ground-state phase transitions belong to the universality classes with central charge c = m / 2, where m is an integer. The models are diagonalized by automatically obtained transformations, many of which are different from the Jordan-Wigner transformation. The free energies, correlation functions, string order parameters, exponents, central charges, and the phase diagram are obtained. Most of the examples consist of the stabilizers of the cluster state. A unified structure of the one-dimensional XY and cluster-type spin chains is revealed, and other series of solvable models can be obtained through this formula.

Poly[bis­{3,3′-[(biphenyl-4,4′-di­yl)dimethyl­ene]diimidazol-1-ium} γ-octa­molybdate(VI)

PubMed Central

Liu, Hongsheng; Su, Lianjiang; Wang, Limin; Li, Weihong

2010-01-01

In the title compound, {(C20H20N4)2[Mo8O26]}n, the asymmetric unit contains half of an [Mo8O26]4− anion and one 3,3′-[(biphenyl-4,4′-di­yl)dimethyl­ene]diimidazol-1-ium dication. In the anion, four distorted [MoO6] octa­hedra are connected via edge-sharing, forming an [Mo4O13]2− building block, composed of Mo—O(t), Mo—O(μ2), Mo—O(μ3) and Mo—O(μ4) units, with Mo—O distances ranging from 1.6858 (15) to 2.4785 (13) Å. The γ-type [Mo8O26]4− anion is completed by crystallographic inversion symmetry and is linked into an infinite chain along [100] by corner-sharing. The anionic chains and the cations are joined by N—H⋯O hydrogen bonds, generating layers extending parallel to (001). PMID:21580534

Quantum transverse-field Ising model on an infinite tree from matrix product states

NASA Astrophysics Data System (ADS)

Nagaj, Daniel; Farhi, Edward; Goldstone, Jeffrey; Shor, Peter; Sylvester, Igor

2008-06-01

We give a generalization to an infinite tree geometry of Vidal’s infinite time-evolving block decimation (iTEBD) algorithm [G. Vidal, Phys. Rev. Lett. 98, 070201 (2007)] for simulating an infinite line of quantum spins. We numerically investigate the quantum Ising model in a transverse field on the Bethe lattice using the matrix product state ansatz. We observe a second order phase transition, with certain key differences from the transverse field Ising model on an infinite spin chain. We also investigate a transverse field Ising model with a specific longitudinal field. When the transverse field is turned off, this model has a highly degenerate ground state as opposed to the pure Ising model whose ground state is only doubly degenerate.

A motif for infinite metal atom wires.

PubMed

Yin, Xi; Warren, Steven A; Pan, Yung-Tin; Tsao, Kai-Chieh; Gray, Danielle L; Bertke, Jeffery; Yang, Hong

2014-12-15

A new motif for infinite metal atom wires with tunable compositions and properties is developed based on the connection between metal paddlewheel and square planar complex moieties. Two infinite Pd chain compounds, [Pd4(CO)4(OAc)4Pd(acac)2] 1 and [Pd4(CO)4(TFA)4Pd(acac)2] 2, and an infinite Pd-Pt heterometallic chain compound, [Pd4(CO)4(OAc)4Pt(acac)2] 3, are identified by single-crystal X-ray diffraction analysis. In these new structures, the paddlewheel moiety is a Pd four-membered ring coordinated by bridging carboxylic ligands and μ2 carbonyl ligands. The planar moiety is either Pd(acac)2 or Pt(acac)2 (acac = acetylacetonate). These moieties are connected by metallophilic interactions. The results showed that these one-dimensional metal wire compounds have photoluminescent properties that are tunable by changing ligands and metal ions. 3 can also serve as a single source precursor for making Pd4Pt bimetallic nanostructures with precise control of metal composition. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Infinite coherence time of edge spins in finite-length chains

NASA Astrophysics Data System (ADS)

Maceira, Ivo A.; Mila, Frédéric

2018-02-01

Motivated by the recent observation that exponentially long coherence times can be achieved for edge spins in models with strong zero modes, we study the impact of level crossings in finite-length spin chains on the dynamics of the edge spins. Focusing on the X Y spin-1 /2 chain with a transverse or longitudinal magnetic field, two models relevant to understanding recent experimental results on cobalt adatoms, we show that the edge spins can remain coherent for an infinite time even for a finite-length chain if the magnetic field is tuned to a value at which there is a level crossing. Furthermore, we show that the edge spins remain coherent for any initial state for the integrable case of a transverse field because all states have level crossings at the same value of the field, while the coherence time is increasingly large for lower temperatures in the case of a longitudinal field, which is nonintegrable.

Layered transition metal carboxylates: synthesis, structural aspects and observation of multi-step magnetic transition through phase diagram.

PubMed

Sen, Rupam; Mal, Dasarath; Lopes, Armandina M L; Brandão, Paula; Araújo, João P; Lin, Zhi

2013-10-01

Two new layered transition metal carboxylate frameworks, [Co3(L)2(H2O)6]·2H2O () and [Ni3(L)2(H2O)6]·2H2O () (L = tartronate anion or hydroxymalonic acid), have been synthesized and characterized by X-ray single crystal analysis. Both compounds have similar 2D structures. In both compounds there are two types of metal centers where one center is doubly bridged by the alkoxy oxygen atoms through μ2-O bridging to form a 1D infinite chain parallel to the crystallographic b-axis with the corners shared between the metal polyhedra. Magnetic susceptibility measurements revealed the existence of antiferromagnetic short range correlations between Co(Ni) intra-chain metal centers (with exchange constants JCo = -22.6 and JNi = -35.4 K). At low temperatures, long range order is observed in both compounds at Néel temperatures of 11 (for ) and 16 (for ) K, revealing that other exchange interactions, rather than the intra-chain ones, play a role in these systems. Whereas compound has an antiferromagnetic ground state, compound exhibits a ferromagnetic component, probably due to spin canting. Isothermal magnetization data unveiled a rich phase diagram with three metamagnetic phase transitions below 8 K in compound .

A high frequency analysis of electromagnetic plane wave scattering by perfectly-conducting semi-infinite parallel plate and rectangular waveguides with absorber coated inner walls

NASA Technical Reports Server (NTRS)

Noh, H. M.; Pathak, P. H.

1986-01-01

An approximate but sufficiently accurate high frequency solution which combines the uniform geometrical theory of diffraction (UTD) and the aperture integration (AI) method is developed for analyzing the problem of electromagnetic (EM) plane wave scattering by an open-ended, perfectly-conducting, semi-infinite hollow rectangular waveguide (or duct) with a thin, uniform layer of lossy or absorbing material on its inner wall, and with a planar termination inside. In addition, a high frequency solution for the EM scattering by a two dimensional (2-D), semi-infinite parallel plate waveguide with a absorber coating on the inner walls is also developed as a first step before analyzing the open-ended semi-infinite three dimensional (3-D) rectangular waveguide geometry. The total field scattered by the semi-infinite waveguide consists firstly of the fields scattered from the edges of the aperture at the open-end, and secondly of the fields which are coupled into the waveguide from the open-end and then reflected back from the interior termination to radiate out of the open-end. The first contribution to the scattered field can be found directly via the UTD ray method. The second contribution is found via the AI method which employs rays to describe the fields in the aperture that arrive there after reflecting from the interior termination. It is assumed that the direction of the incident plane wave and the direction of observation lie well inside the forward half space tht exists outside the half space containing the semi-infinite waveguide geometry. Also, the medium exterior to the waveguide is assumed to be free space.

Experimental Investigations, Modeling, and Analyses of High-Temperature Devices for Space Applications. Part 1

DTIC Science & Technology

1999-01-01

Cylinder and Another Interior Shell of Different Length (Reid and Tennant 1973) 429 C. 1.19. View Factors between Two Infinitely-Long Parallel and Opposed...by Another Parallel Cylinder of Different Radius 433 X C. 1.21. View Factor between Two Parallel and Opposed Cylinders of Unequal Radii and Equal...Length (Juul 1982) 435 C. 1.22. View Factor between Two Parallel Cylindrical Sections at Different Levels and of Different Length 439 C.2 CALCULATION OF

Simplification of Markov chains with infinite state space and the mathematical theory of random gene expression bursts.

PubMed

Jia, Chen

2017-09-01

Here we develop an effective approach to simplify two-time-scale Markov chains with infinite state spaces by removal of states with fast leaving rates, which improves the simplification method of finite Markov chains. We introduce the concept of fast transition paths and show that the effective transitions of the reduced chain can be represented as the superposition of the direct transitions and the indirect transitions via all the fast transition paths. Furthermore, we apply our simplification approach to the standard Markov model of single-cell stochastic gene expression and provide a mathematical theory of random gene expression bursts. We give the precise mathematical conditions for the bursting kinetics of both mRNAs and proteins. It turns out that random bursts exactly correspond to the fast transition paths of the Markov model. This helps us gain a better understanding of the physics behind the bursting kinetics as an emergent behavior from the fundamental multiscale biochemical reaction kinetics of stochastic gene expression.

Simplification of Markov chains with infinite state space and the mathematical theory of random gene expression bursts

NASA Astrophysics Data System (ADS)

Jia, Chen

2017-09-01

Here we develop an effective approach to simplify two-time-scale Markov chains with infinite state spaces by removal of states with fast leaving rates, which improves the simplification method of finite Markov chains. We introduce the concept of fast transition paths and show that the effective transitions of the reduced chain can be represented as the superposition of the direct transitions and the indirect transitions via all the fast transition paths. Furthermore, we apply our simplification approach to the standard Markov model of single-cell stochastic gene expression and provide a mathematical theory of random gene expression bursts. We give the precise mathematical conditions for the bursting kinetics of both mRNAs and proteins. It turns out that random bursts exactly correspond to the fast transition paths of the Markov model. This helps us gain a better understanding of the physics behind the bursting kinetics as an emergent behavior from the fundamental multiscale biochemical reaction kinetics of stochastic gene expression.

From {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}O(MoO{sub 4}){sub 4}]{sup 6-} to {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})]{sup 6-} infinite chains in A{sub 6}U{sub 2}Mo{sub 4}O{sub 21} (A=Na, K, Rb, Cs) compounds: Synthesis and crystal structure of Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yagoubi, S.; Groupe de Radiochimie, Institut de Physique Nucleaire d'Orsay, Universite Paris-Sud XI, 91406 Orsay Cedex; Obbade, S., E-mail: said.obbade@phelma.grenoble-inp.f

2011-05-15

A new caesium uranyl molybdate belonging to the M{sub 6}U{sub 2}Mo{sub 4}O{sub 21} family has been synthesized by solid-state reaction and its structure determined from single-crystal X-ray diffraction data. Contrary to the other alkali uranyl molybdates of this family (A=Na, K, Rb) where molybdenum atoms adopt only tetrahedral coordination and which can be formulated A{sub 6}[(UO{sub 2}){sub 2}O(MoO{sub 4}){sub 4}], the caesium compound Cs{sub 6}U{sub 2}Mo{sub 4}O{sub 21} should be written Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})] with molybdenum atoms in tetrahedral and square pyramidal environments. Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})] crystallizes in the triclinic symmetry withmore » space group P1-bar and a=10.4275(14) A, b=15.075(2) A, c=17.806(2) A, {alpha}=70.72(1){sup o}, {beta}=80.38(1){sup o} and {gamma}=86.39(1){sup o}, V=2604.7(6) A{sup 3}, Z=4, {rho}{sub mes}=5.02(2) g/cm{sup 3} and {rho}{sub cal}=5.08(3) g/cm{sup 3}. A full-matrix least-squares refinement on the basis of F{sup 2} yielded R{sub 1}=0.0464 and wR{sub 2}=0.0950 for 596 parameters with 6964 independent reflections with I{>=}2{sigma}(I) collected on a BRUKER AXS diffractometer with Mo(K{alpha}) radiation and a CCD detector. The crystal structure of Cs compound is characterized by {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})]{sup 6-} parallels chains built from U{sub 2}O{sub 13} dimeric units, MoO{sub 4} tetrahedra and MoO{sub 5} square pyramids, whereas, Na, K and Rb compounds are characterized by {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}O(MoO{sub 4}){sub 4}]{sup 6-} parallel chains formulated simply of U{sub 2}O{sub 13} units and MoO{sub 4} tetrahedra. Infrared spectroscopy measurements using powdered samples synthesized by solid-state reaction, confirm the structural results. The thermal stability and the electrical conductivity are also studied. The four compounds decompose at low temperature (between 540 and 610 {sup o}C). -- Graphical abstract: The staking of {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})]{sup 6-} infinite uranyl molybdate ribbons in the Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})] structure. Display Omitted Highlights: {yields} Cs{sub 6}U{sub 2}Mo{sub 4}O{sub 2} a new compound with bidimensional crystal structure, characterized by infinite uranyl molybdate chains. {yields} Crystal structure similar to these of the compounds containing Na, K, Rb. {yields} Molybdenum atoms surrounded by five oxygen atoms to form an original and strongly distorted MoO{sub 5} environment. {yields} The chains arrangement illustrates the key role of the alkaline ionic radius, in the crystal structure distortion for Cs compound.« less

Graph determined symbolic dynamics and hybrid systems

NASA Astrophysics Data System (ADS)

Ayers, Kimberly Danielle

In this paper we explore the concept of symbolic dynamical systems whose structure is determined by a directed graph, and then discrete-continuous hybrid systems that arise from such dynamical systems. Typically, symbolic dynamics involve the study of a left shift of a bi-infinite sequence. We examine the case when the bi-infinite system is dictated by a graph; that is, the sequence is a bi-infinite path of a directed graph. We then use the concept to study a system of dynamical systems all on the same compact space M, where "switching" between the systems occurs as given by the bi-infinite sequence in question. The concepts of limit sets, chain recurrent sets, chaos, and Morse sets for these systems are explored.

Syntheses, structures, and properties of two new zinc(II) metal-organic frameworks based on flexible 1,6-bis(2-methyl-imidazole-1-yl)hexane ligand

NASA Astrophysics Data System (ADS)

Jin, Jun-Cheng; Fu, Ai-Yun; Li, Dian; Chang, Wen-Gui; Wu, Ju; Yang, Mei; Xie, Cheng-Gen; Xu, Guang-Nian; Cai, An-Xing; Wu, Ai-Hua

2014-11-01

Two new zinc(II) metal-organic compounds of [Zn(ADC)(bimh)]n (1) and [Zn(ADA)(bimh)]n (2) (H2ADC = 1,3-adamantanedicarboxylic acid, H2ADA = 1,3-adamantanediacetic acid, bimh = 1,6-bis(2-methyl-imidazole-1-yl)-hexane, have been structurally characterized by X-ray diffraction analysis. In compound 1, the zinc(II) ions are bridged by ADC and bimh ligands to form a 1D looped chain. In compound 2, the ADA molecules alternately bridge Zn(II) atoms to form infinite chains, and then the 1D chain is connected through the bimh ligand resulting in an undulating infinite two-dimensional (2D) polymeric network. Additionally, TG analysis, XRPD and fluorescent properties for compounds 1 and 2 are also measured and discussed.

Killing and Noether Symmetries of Plane Symmetric Spacetime

NASA Astrophysics Data System (ADS)

Shamir, M. Farasat; Jhangeer, Adil; Bhatti, Akhlaq Ahmad

2013-09-01

This paper is devoted to investigate the Killing and Noether symmetries of static plane symmetric spacetime. For this purpose, five different cases have been discussed. The Killing and Noether symmetries of Minkowski spacetime in cartesian coordinates are calculated as a special case and it is found that Lie algebra of the Lagrangian is 10 and 17 dimensional respectively. The symmetries of Taub's universe, anti-deSitter universe, self similar solutions of infinite kind for parallel perfect fluid case and self similar solutions of infinite kind for parallel dust case are also explored. In all the cases, the Noether generators are calculated in the presence of gauge term. All these examples justify the conjecture that Killing symmetries form a subalgebra of Noether symmetries (Bokhari et al. in Int. J. Theor. Phys. 45:1063, 2006).

Photon escape probabilities in a semi-infinite plane-parallel medium. [from electron plasma surrounding galactic X-ray sources

NASA Technical Reports Server (NTRS)

Williams, A. C.; Elsner, R. F.; Weisskopf, M. C.; Darbro, W.

1984-01-01

It is shown in this work how to obtain the probabilities of photons escaping from a cold electron plasma environment after having undergone an arbitrary number of scatterings. This is done by retaining the exact differential cross section for Thomson scattering as opposed to using its polarization and angle averaged form. The results are given in the form of recursion relations. The geometry used is the semi-infinite plane-parallel geometry witlh a photon source located on a plane at an arbitrary optical depth below the surface. Analytical expressions are given for the probabilities which are accurate over a wide range of initial optical depth. These results can be used to model compact X-ray galactic sources which are surrounded by an electron-rich plasma.

Emission of sound from turbulence convected by a parallel flow in the presence of solid boundaries

NASA Technical Reports Server (NTRS)

Goldstein, M. E.; Rosenbaum, B. M.

1973-01-01

A theoretical description is given of the sound emitted from an arbitrary point in a parallel or nearly parallel turbulent shear flow confined to a region near solid boundaries. The analysis begins with Lighthill's formulation of aerodynamic noise and assumes that the turbulence is axisymmetric. Specific results are obtained for the sound emitted from an arbitrary point in a turbulent flow within a semi-infinite, open-ended duct.

A Novel Coordination Polymer Based on Trinuclear Cobalt Building Blocks Cluster: Synthesis, Crystal Structure, and Properties

NASA Astrophysics Data System (ADS)

Lu, J. F.; Tang, Z. H.; Shi, J.; Ge, H. G.; Jiang, M.; Song, J.; Jin, L. X.

2017-12-01

The title compound {[Co3(μ3-OH)(μ2-H2O)2(H2O)5(BTC)2] · 6H2O} n (H3BTC is a 1,3,5-benzenetricarboxylic acid) was prepared and characterized by single crystal and powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric and elemental analyses. The single crystal X-ray diffraction reveals that the title compound consists of 1D infinite zigzag chains which were constructed by trinuclear cobalt cluster and BTC3- ligand. Neighbouring above-mentioned 1D infinite zigzag chains are further linked by intermolecular hydrogen bonding to form a 3D supermolecular structure. In addition, the luminescent properties of the title compound were investigated.

Direct Connection between the RII Chain and the Nonautonomous Discrete Modified KdV Lattice

NASA Astrophysics Data System (ADS)

Maeda, Kazuki; Tsujimoto, Satoshi

2013-11-01

The spectral transformation technique for symmetric RII polynomials is developed. Use of this technique reveals that the nonautonomous discrete modified KdV (nd-mKdV) lattice is directly connected with the RII chain. Hankel determinant solutions to the semi-infinite nd-mKdV lattice are also presented.

A Study of the Behavior and Micromechanical Modelling of Granular Soil. Volume 2. An Experimental Investigation of the Behavior of Granular Media Under Load

DTIC Science & Technology

1991-05-22

infinite number of possi’le crystal orientations is assumed, this infinitely sided polyhedron becomes a curved yield surface. Plastic strain in the...families, each surface of yield polyhedron mentioned above expands and shifts differently. These slip directions are all more or less parallel to the...result, only the monotonic portion of test D29 was corrected for membrane compliance and used as part of the monotonic proportional test database

Parallel Markov chain Monte Carlo - bridging the gap to high-performance Bayesian computation in animal breeding and genetics.

PubMed

Wu, Xiao-Lin; Sun, Chuanyu; Beissinger, Timothy M; Rosa, Guilherme Jm; Weigel, Kent A; Gatti, Natalia de Leon; Gianola, Daniel

2012-09-25

Most Bayesian models for the analysis of complex traits are not analytically tractable and inferences are based on computationally intensive techniques. This is true of Bayesian models for genome-enabled selection, which uses whole-genome molecular data to predict the genetic merit of candidate animals for breeding purposes. In this regard, parallel computing can overcome the bottlenecks that can arise from series computing. Hence, a major goal of the present study is to bridge the gap to high-performance Bayesian computation in the context of animal breeding and genetics. Parallel Monte Carlo Markov chain algorithms and strategies are described in the context of animal breeding and genetics. Parallel Monte Carlo algorithms are introduced as a starting point including their applications to computing single-parameter and certain multiple-parameter models. Then, two basic approaches for parallel Markov chain Monte Carlo are described: one aims at parallelization within a single chain; the other is based on running multiple chains, yet some variants are discussed as well. Features and strategies of the parallel Markov chain Monte Carlo are illustrated using real data, including a large beef cattle dataset with 50K SNP genotypes. Parallel Markov chain Monte Carlo algorithms are useful for computing complex Bayesian models, which does not only lead to a dramatic speedup in computing but can also be used to optimize model parameters in complex Bayesian models. Hence, we anticipate that use of parallel Markov chain Monte Carlo will have a profound impact on revolutionizing the computational tools for genomic selection programs.

Parallel Markov chain Monte Carlo - bridging the gap to high-performance Bayesian computation in animal breeding and genetics

PubMed Central

2012-01-01

Background Most Bayesian models for the analysis of complex traits are not analytically tractable and inferences are based on computationally intensive techniques. This is true of Bayesian models for genome-enabled selection, which uses whole-genome molecular data to predict the genetic merit of candidate animals for breeding purposes. In this regard, parallel computing can overcome the bottlenecks that can arise from series computing. Hence, a major goal of the present study is to bridge the gap to high-performance Bayesian computation in the context of animal breeding and genetics. Results Parallel Monte Carlo Markov chain algorithms and strategies are described in the context of animal breeding and genetics. Parallel Monte Carlo algorithms are introduced as a starting point including their applications to computing single-parameter and certain multiple-parameter models. Then, two basic approaches for parallel Markov chain Monte Carlo are described: one aims at parallelization within a single chain; the other is based on running multiple chains, yet some variants are discussed as well. Features and strategies of the parallel Markov chain Monte Carlo are illustrated using real data, including a large beef cattle dataset with 50K SNP genotypes. Conclusions Parallel Markov chain Monte Carlo algorithms are useful for computing complex Bayesian models, which does not only lead to a dramatic speedup in computing but can also be used to optimize model parameters in complex Bayesian models. Hence, we anticipate that use of parallel Markov chain Monte Carlo will have a profound impact on revolutionizing the computational tools for genomic selection programs. PMID:23009363

Structure cristalline, caractérisation spectroscopique, calcul DFT et analyse de surface Hirshfeld du perchlorate de p-toluidinium.

PubMed

Ben Jomaa, Meriam; Chebbi, Hammouda; Fakhar Bourguiba, Noura; Zid, Mohamed Faouzi

2018-02-01

The synthesis of p -toluidinium perchlorate (systematic name: 4-methyl-anilinium perchlorate), C 7 H 10 N + ·ClO 4 - , was carried out from an aqueous reaction of perchloric acid with p -toluidine. This compound was characterized by powder XRD, IR and UV-Vis spectroscopy. The structure was further confirmed by a single-crystal X-ray diffraction study. The crystal structure is formed by a succession of two-dimensional mol-ecular layers consisting of perchlorate anions and organic cations parallel to the (100) plane and located at x = 2 n  + ½ ( n ∈ Z ). Each mixed layer is formed by infinite chains {C 7 H 10 N + ·ClO 4 - } n parallel to the [010] direction and developing along the c axis, generating R 2 4 (8), R 2 2 (4) and R 4 4 (12) graph-set motifs. The results of a theoretical study using the DFT method at the B3LYP/6-311++G(d,p) level are in good agreement with the experimental data. Hirshfeld surface and fingerprint plots reveal that the structure is dominated by O⋯H/H⋯O (54.2%), H⋯H (26.9%) and C-H ⋯π (14.3%) contacts. The studied crystal was refined as a two-component twin.

Density functional theory study of the conformational space of an infinitely long polypeptide chain

NASA Astrophysics Data System (ADS)

Ireta, Joel; Scheffler, Matthias

2009-08-01

The backbone conformational space of infinitely long polyalanine is investigated with density-functional theory and mapping the potential energy surface in terms of (L, θ) cylindrical coordinates. A comparison of the obtained (L, θ) Ramachandran-like plot with results from an extended set of protein structures shows excellent conformity, with the exception of the polyproline II region. It is demonstrated the usefulness of infinitely long polypeptide models for investigating the influence of hydrogen bonding and its cooperative effect on the backbone conformations. The results imply that hydrogen bonding together with long-range electrostatics is the main actuator for most of the structures assumed by protein residues.

H2-control and the separation principle for discrete-time jump systems with the Markov chain in a general state space

NASA Astrophysics Data System (ADS)

Figueiredo, Danilo Zucolli; Costa, Oswaldo Luiz do Valle

2017-10-01

This paper deals with the H2 optimal control problem of discrete-time Markov jump linear systems (MJLS) considering the case in which the Markov chain takes values in a general Borel space ?. It is assumed that the controller has access only to an output variable and to the jump parameter. The goal, in this case, is to design a dynamic Markov jump controller such that the H2-norm of the closed-loop system is minimised. It is shown that the H2-norm can be written as the sum of two H2-norms, such that one of them does not depend on the control, and the other one is obtained from the optimal filter for an infinite-horizon filtering problem. This result can be seen as a separation principle for MJLS with Markov chain in a Borel space ? considering the infinite time horizon case.

SQDFT: Spectral Quadrature method for large-scale parallel O(N) Kohn-Sham calculations at high temperature

NASA Astrophysics Data System (ADS)

Suryanarayana, Phanish; Pratapa, Phanisri P.; Sharma, Abhiraj; Pask, John E.

2018-03-01

We present SQDFT: a large-scale parallel implementation of the Spectral Quadrature (SQ) method for O(N) Kohn-Sham Density Functional Theory (DFT) calculations at high temperature. Specifically, we develop an efficient and scalable finite-difference implementation of the infinite-cell Clenshaw-Curtis SQ approach, in which results for the infinite crystal are obtained by expressing quantities of interest as bilinear forms or sums of bilinear forms, that are then approximated by spatially localized Clenshaw-Curtis quadrature rules. We demonstrate the accuracy of SQDFT by showing systematic convergence of energies and atomic forces with respect to SQ parameters to reference diagonalization results, and convergence with discretization to established planewave results, for both metallic and insulating systems. We further demonstrate that SQDFT achieves excellent strong and weak parallel scaling on computer systems consisting of tens of thousands of processors, with near perfect O(N) scaling with system size and wall times as low as a few seconds per self-consistent field iteration. Finally, we verify the accuracy of SQDFT in large-scale quantum molecular dynamics simulations of aluminum at high temperature.

Limitations of discrete-time quantum walk on a one-dimensional infinite chain

NASA Astrophysics Data System (ADS)

Lin, Jia-Yi; Zhu, Xuanmin; Wu, Shengjun

2018-04-01

How well can we manipulate the state of a particle via a discrete-time quantum walk? We show that the discrete-time quantum walk on a one-dimensional infinite chain with coin operators that are independent of the position can only realize product operators of the form eiξ A ⊗1p, which cannot change the position state of the walker. We present a scheme to construct all possible realizations of all the product operators of the form eiξ A ⊗1p. When the coin operators are dependent on the position, we show that the translation operators on the position can not be realized via a DTQW with coin operators that are either the identity operator 1 or the Pauli operator σx.

Synthesis, crystal structure and optical properties of a novel sodium lead pentaborate, NaPbB{sub 5}O{sub 9}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Min; Graduate University of Chinese Academy of Sciences, Beijing 100049; Pan, Shilie, E-mail: slpan@ms.xjb.ac.c

A novel sodium lead pentaborate, NaPbB{sub 5}O{sub 9}, has been successfully synthesized by standard solid-state reaction. The single-crystal X-ray structural analysis showed that NaPbB{sub 5}O{sub 9} crystallizes in the monoclinic space group P2{sub 1}/c with a=6.5324(10) A, b=13.0234(2) A, c=8.5838(10) A, {beta}=104.971(10){sup o}, and Z=4. The crystal structure is composed of double ring [B{sub 5}O{sub 9}]{sup 3-} units, [PbO{sub 7}] and [NaO{sub 7}] polyhedra. [B{sub 5}O{sub 9}]{sup 3-} groups connect with each other forming two-dimensional infinite {sub {infinity}}[B{sub 5}O{sub 9}]{sup 3-} layers, while [PbO{sub 7}] and [NaO{sub 7}] polyhedra are located between the layers. [PbO{sub 7}] polyhedra linked together viamore » corner-sharing O atom forming novel infinite {sub {infinity}}[PbO{sub 6}] chains along the c axis. The thermal behavior, IR spectrum and the optical diffuse reflectance spectrum of NaPbB{sub 5}O{sub 9} were reported. -- Graphical abstract: A new phase, NaPbB{sub 5}O{sub 9}, has been discovered in the ternary M{sub 2}O-PbO-B{sub 2}O{sub 3} (M=alkali-metal) system. The crystal structure consists of a novel infinite {sub {infinity}}[PbO{sub 6}] chains. Display Omitted Research highlights: NaPbB{sub 5}O{sub 9} is the first borate discovered in the ternary M{sub 2}O-PbO-B{sub 2}O{sub 3} (M=alkali-metal) system. NaPbB{sub 5}O{sub 9} crystal structure includes a two-dimensional infinite {sub {infinity}}[B{sub 5}O{sub 9}]{sup 3-} layers and a novel one-dimensional infinite {sub {infinity}}[PbO{sub 6}] chains. [PbO{sub 7}] polyhedron has a highly asymmetric bonding configuration.« less

Analytical study on the generalized Davydov model in the alpha helical proteins

NASA Astrophysics Data System (ADS)

Wang, Pan; Xiao, Shu-Hong; Chen, Li; Yang, Gang

2017-06-01

In this paper, we investigate the dynamics of a generalized Davydov model derived from an infinite chain of alpha helical protein molecules which contain three hydrogen bonding spines running almost parallel to the helical axis. Through the introduction of the auxiliary function, the bilinear form, one-, two- and three-soliton solutions for the generalized Davydov model are obtained firstly. Propagation and interactions of solitons have been investigated analytically and graphically. The amplitude of the soliton is only related to the complex parameter μ and real parameter 𝜃 with a range of [0, 2π]. The velocity of the soliton is only related to the complex parameter μ, real parameter 𝜃, lattice parameter 𝜀, and physical parameters β1, β3 and β4. Overtaking and head-on interactions of two and three solitons are presented. The common in the interactions of three solitons is the directions of the solitons change after the interactions. The soliton derived in this paper is expected to have potential applications in the alpha helical proteins.

Dynamics of hot random quantum spin chains: from anyons to Heisenberg spins

NASA Astrophysics Data System (ADS)

Parameswaran, Siddharth; Potter, Andrew; Vasseur, Romain

2015-03-01

We argue that the dynamics of the random-bond Heisenberg spin chain are ergodic at infinite temperature, in contrast to the many-body localized behavior seen in its random-field counterpart. First, we show that excited-state real-space renormalization group (RSRG-X) techniques suffer from a fatal breakdown of perturbation theory due to the proliferation of large effective spins that grow without bound. We repair this problem by deforming the SU (2) symmetry of the Heisenberg chain to its `anyonic' version, SU(2)k , where the growth of effective spins is truncated at spin S = k / 2 . This enables us to construct a self-consistent RSRG-X scheme that is particularly simple at infinite temperature. Solving the flow equations, we compute the excited-state entanglement and show that it crosses over from volume-law to logarithmic scaling at a length scale ξk ~eαk3 . This reveals that (a) anyon chains have random-singlet-like excited states for any finite k; and (b) ergodicity is restored in the Heisenberg limit k --> ∞ . We acknowledge support from the Quantum Materials program of LBNL (RV), the Gordon and Betty Moore Foundation (ACP), and UC Irvine startup funds (SAP).

On Condensation Properties of Bethe Roots Associated with the XXZ Chain

NASA Astrophysics Data System (ADS)

Kozlowski, Karol K.

2018-02-01

I prove that the Bethe roots describing either the ground state or a certain class of "particle-hole" excited states of the XXZ spin-1/2 chain in any sector with magnetisation m \\in [0;1/2] exist, are uniquely defined, and form, in the infinite volume limit, a dense distribution on a subinterval of R. The results hold for any value of the anisotropy {Δ ≥ -1}. In fact, I establish an even stronger result, namely the existence of an all order asymptotic expansion of the counting function associated with such roots. As a corollary, these results allow one to prove the existence and form of the infinite volume limit of various observables attached to the model -the excitation energy, momentum, the zero temperature correlation functions, so as to name a few- that were argued earlier in the literature.

Crystal structure of a looped-chain CoII coordination polymer: catena-poly[[bis-(nitrato-κO)cobalt(II)]bis-[μ-bis-(pyridin-3-ylmeth-yl)sulfane-κ2N:N'

PubMed

Moon, Suk-Hee; Seo, Joobeom; Park, Ki-Min

2017-11-01

The asymmetric unit of the title compound, [Co(NO 3 ) 2 (C 12 H 12 N 2 S) 2 ] n , contains a bis-(pyridin-3-ylmeth-yl)sulfane ( L ) ligand, an NO 3 - anion and half a Co II cation, which lies on an inversion centre. The Co II cation is six-coordinated, being bound to four pyridine N atoms from four symmetry-related L ligands. The remaining coordination sites are occupied by two O atoms from two symmetry-related nitrate anions in a monodentate manner. Thus, the Co II centre adopts a distorted octa-hedral geometry. Two symmetry-related L ligands are connected by two symmetry-related Co II cations, forming a 20-membered cyclic dimer, in which the Co II atoms are separated by 10.2922 (7) Å. The cyclic dimers are connected to each other by sharing Co II atoms, giving rise to the formation of an infinite looped chain propagating along the [101] direction. Inter-molecular C-H⋯π (H⋯ring centroid = 2.89 Å) inter-actions between one pair of corresponding L ligands and C-H⋯O hydrogen bonds between the L ligands and the nitrate anions occur in the looped chain. In the crystal, adjacent looped chains are connected by inter-molecular π-π stacking inter-actions [centroid-to-centroid distance = 3.8859 (14) Å] and C-H⋯π hydrogen bonds (H⋯ring centroid = 2.65 Å), leading to the formation of layers parallel to (101). These layers are further connected through C-H⋯O hydrogen bonds between the layers, resulting in the formation of a three-dimensional supra-molecular architecture.

SQDFT: Spectral Quadrature method for large-scale parallel O ( N ) Kohn–Sham calculations at high temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suryanarayana, Phanish; Pratapa, Phanisri P.; Sharma, Abhiraj

We present SQDFT: a large-scale parallel implementation of the Spectral Quadrature (SQ) method formore » $$\\mathscr{O}(N)$$ Kohn–Sham Density Functional Theory (DFT) calculations at high temperature. Specifically, we develop an efficient and scalable finite-difference implementation of the infinite-cell Clenshaw–Curtis SQ approach, in which results for the infinite crystal are obtained by expressing quantities of interest as bilinear forms or sums of bilinear forms, that are then approximated by spatially localized Clenshaw–Curtis quadrature rules. We demonstrate the accuracy of SQDFT by showing systematic convergence of energies and atomic forces with respect to SQ parameters to reference diagonalization results, and convergence with discretization to established planewave results, for both metallic and insulating systems. Here, we further demonstrate that SQDFT achieves excellent strong and weak parallel scaling on computer systems consisting of tens of thousands of processors, with near perfect $$\\mathscr{O}(N)$$ scaling with system size and wall times as low as a few seconds per self-consistent field iteration. Finally, we verify the accuracy of SQDFT in large-scale quantum molecular dynamics simulations of aluminum at high temperature.« less

SQDFT: Spectral Quadrature method for large-scale parallel O ( N ) Kohn–Sham calculations at high temperature

DOE PAGES

Suryanarayana, Phanish; Pratapa, Phanisri P.; Sharma, Abhiraj; ...

2017-12-07

We present SQDFT: a large-scale parallel implementation of the Spectral Quadrature (SQ) method formore » $$\\mathscr{O}(N)$$ Kohn–Sham Density Functional Theory (DFT) calculations at high temperature. Specifically, we develop an efficient and scalable finite-difference implementation of the infinite-cell Clenshaw–Curtis SQ approach, in which results for the infinite crystal are obtained by expressing quantities of interest as bilinear forms or sums of bilinear forms, that are then approximated by spatially localized Clenshaw–Curtis quadrature rules. We demonstrate the accuracy of SQDFT by showing systematic convergence of energies and atomic forces with respect to SQ parameters to reference diagonalization results, and convergence with discretization to established planewave results, for both metallic and insulating systems. Here, we further demonstrate that SQDFT achieves excellent strong and weak parallel scaling on computer systems consisting of tens of thousands of processors, with near perfect $$\\mathscr{O}(N)$$ scaling with system size and wall times as low as a few seconds per self-consistent field iteration. Finally, we verify the accuracy of SQDFT in large-scale quantum molecular dynamics simulations of aluminum at high temperature.« less

On an adaptive preconditioned Crank-Nicolson MCMC algorithm for infinite dimensional Bayesian inference

NASA Astrophysics Data System (ADS)

Hu, Zixi; Yao, Zhewei; Li, Jinglai

2017-03-01

Many scientific and engineering problems require to perform Bayesian inference for unknowns of infinite dimension. In such problems, many standard Markov Chain Monte Carlo (MCMC) algorithms become arbitrary slow under the mesh refinement, which is referred to as being dimension dependent. To this end, a family of dimensional independent MCMC algorithms, known as the preconditioned Crank-Nicolson (pCN) methods, were proposed to sample the infinite dimensional parameters. In this work we develop an adaptive version of the pCN algorithm, where the covariance operator of the proposal distribution is adjusted based on sampling history to improve the simulation efficiency. We show that the proposed algorithm satisfies an important ergodicity condition under some mild assumptions. Finally we provide numerical examples to demonstrate the performance of the proposed method.

Markov chain sampling of the O(n) loop models on the infinite plane

NASA Astrophysics Data System (ADS)

Herdeiro, Victor

2017-07-01

A numerical method was recently proposed in Herdeiro and Doyon [Phys. Rev. E 94, 043322 (2016), 10.1103/PhysRevE.94.043322] showing a precise sampling of the infinite plane two-dimensional critical Ising model for finite lattice subsections. The present note extends the method to a larger class of models, namely the O(n) loop gas models for n ∈(1 ,2 ] . We argue that even though the Gibbs measure is nonlocal, it is factorizable on finite subsections when sufficient information on the loops touching the boundaries is stored. Our results attempt to show that provided an efficient Markov chain mixing algorithm and an improved discrete lattice dilation procedure the planar limit of the O(n) models can be numerically studied with efficiency similar to the Ising case. This confirms that scale invariance is the only requirement for the present numerical method to work.

Evaluation of the operatorial Q-system for non-compact super spin chains

NASA Astrophysics Data System (ADS)

Frassek, Rouven; Marboe, Christian; Meidinger, David

2017-09-01

We present an approach to evaluate the full operatorial Q-system of all u(p,q\\Big|r+s) -invariant spin chains with representations of Jordan-Schwinger type. In particular, this includes the super spin chain of planar N=4 super Yang-Mills theory at one loop in the presence of a diagonal twist. Our method is based on the oscillator construction of Q-operators. The Q-operators are built as traces over Lax operators which are degenerate solutions of the Yang-Baxter equation. For non-compact representations these Lax operators may contain multiple infinite sums that conceal the form of the resulting functions. We determine these infinite sums and calculate the matrix elements of the lowest level Q-operators. Transforming the Lax operators corresponding to the Q-operators into a representation involving only finite sums allows us to take the supertrace and to obtain the explicit form of the Q-operators in terms of finite matrices for a given magnon sector. Imposing the functional relations, we then bootstrap the other Q-operators from those of the lowest level. We exemplify this approach for non-compact spin - s spin chains and apply it to N=4 at the one-loop level using the BMN vacuum as an example.

Plasmon-Polariton Properties in Metallic Nanosphere Chains

PubMed Central

Jacak, Witold Aleksander; Krasnyj, Jurij; Chepok, Andrej

2015-01-01

The propagation of collective wave type plasmonic excitations along infinite chains of metallic nanospheres has been analyzed, including near-, medium- and far-field contributions to the plasmon dipole interaction with all retardation effects taken into account. It is proven that there exist weakly-damped self-modes of plasmon-polaritons in the chain for which the propagation range is limited by relatively small Ohmic losses only. In this regime, the Lorentz friction irradiation losses on each nanosphere in the chain are ideally compensated by the energy income from the rest of the chain. The completely undamped collective waves were identified in the case of the presence of persistent external excitation of some fragment of the chain. The obtained characteristics of these excitations fit the experimental observations well. PMID:28793415

Chain-reaction crash in traffic flow controlled by taillights

NASA Astrophysics Data System (ADS)

Nagatani, Takashi

2015-02-01

We study the chain-reaction crash (multiple-vehicle collision) in low-visibility condition on a road. In the traffic situation, drivers brake according to taillights of the forward vehicle. The first crash may induce more collisions. We investigate whether or not the first collision induces the chain-reaction crash, numerically and analytically. The dynamic transitions occur from no collisions through a single collision, double collisions and triple collisions, to multiple collisions with decreasing the headway. Also, we find that the dynamic transition occurs from the finite chain reaction to the infinite chain reaction when the headway is less than the critical value. We derive, analytically, the transition points and the region maps for the chain-reaction crash in traffic flow controlled by taillights.

2 + 1 Toda chain. I. Inverse scattering method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipovskii, V.D.; Shirokov, A.V.

A formal scheme of the inverse scattering method is constructed for the2 + 1 Toda chain in the class of rapidly decreasing Cauchy data. Application of the inverse scattering method to the two-dimensional infinite Toda chain was made difficult by the circumstance that this system is a (2 + 1)-dimensional object, i.e., possesses time and two spatial variables, the role of one of these being played by the chain site number. Because of this, our information about the 2 + 1 Toda chain was limited to a rich set of particular solutions of soliton type obtained in the cycle ofmore » studies by the Darboux transformation method.« less

Backscatter RCS for TE and TM excitations of dielectric-filled cavity-backed apertures in two-dimensional bodies

NASA Technical Reports Server (NTRS)

Goggans, Paul M.; Shumpert, Thomas H.

1991-01-01

Transverse electric (TE) and transverse magnetic (TM) scattering from dielectric-filled, cavity-backed apertures in two-dimensional bodies are treated using the method of moments technique to solve a set of combined-field integral equations for the equivalent induced electric and magnetic currents on the exterior of the scattering body and on the associated aperture. Results are presented for the backscatter radar cross section (RCS) versus the electrical size of the scatterer for two different dielectric-filled cavity-backed geometries. The first geometry is a circular cylinder of infinite length which has an infinite length slot aperture along one side. The cavity inside the cylinder is dielectric filled and is also of circular cross section. The two cylinders (external and internal) are of different radii and their respective longitudinal axes are parallel but not collocated. The second is a square cylinder of infinite length which has an infinite length slot aperture along one side. The cavity inside the square cylinder is dielectric-filled and is also of square cross section.

A new antibacterial silver(I) complex incorporating 2,5-dimethylpyrazine and the anti-inflammatory diclofenac.

PubMed

Hamamci Alisir, Sevim; Dege, Necmi

2016-12-01

Ag I -containing coordination complexes have attracted attention because of their photoluminescence properties and antimicrobial activities and, in principle, these properties depend on the nature of the structural topologies. A novel two-dimensional silver(I) complex with the anti-inflammatory diclofenac molecule, namely bis{μ-2-[2-(2,6-dichloroanilino)phenyl]acetato-κ 3 O,O':O}bis(μ-2,5-dimethylpyrazine-κ 2 N:N')silver(I), [Ag 2 (C 14 H 10 Cl 2 NO 2 ) 2 (C 6 H 8 N 2 )] n , (I), has been synthesized and characterized by single-crystal X-ray diffraction, revealing that the Ag I ions are chelated by the carboxylate groups of the anionic 2-[2-(2,6-dichloroanilino)phenyl]acetate (dicl) ligand in a μ 3 -η 1 :η 2 coordination mode. Each dicl ligand links three Ag I atoms to generate a one-dimensional infinite chain. Adjacent chains are connected through 2,5-dimethylpyrazine (dmpyz) ligands to form a two-dimensional layer structure parallel to the crystallographic bc plane. The layers are further connected by C-H...π interactions to generate a three-dimensional supramolecular structure. Additionally, the most striking feature is that the structure contains an intramolecular C-H ...Ag anagostic interaction. Furthermore, the title complex has been tested for its in vitro antibacterial activity and is determined to be highly effective on the studied microorganisms.

Calculation of longitudinal polarizability and second hyperpolarizability of polyacetylene with the coupled perturbed Hartree-Fock/Kohn-Sham scheme: Where it is shown how finite oligomer chains tend to the infinite periodic polymer

NASA Astrophysics Data System (ADS)

Lacivita, Valentina; Rèrat, Michel; Orlando, Roberto; Ferrero, Mauro; Dovesi, Roberto

2012-03-01

The longitudinal polarizability, αxx, and second hyperpolarizability, γxxxx, of polyacetylene are evaluated by using the coupled perturbed Hartree-Fock/Kohn-Sham (HF/KS) scheme as implemented in the periodic CRYSTAL code and a split valence type basis set. Four different density functionals, namely local density approximation (LDA) (pure local), Perdew-Becke-Ernzerhof (PBE) (gradient corrected), PBE0, and B3LYP (hybrid), and the Hartree-Fock Hamiltonian are compared. It is shown that very tight computational conditions must be used to obtain well converged results, especially for γxxxx, that is, very sensitive to the number of k points in reciprocal space when the band gap is small (as for LDA and PBE), and to the extension of summations of the exact exchange series (HF and hybrids). The band gap in LDA is only 0.01 eV: at least 300 k points are required to obtain well converged total energy and equilibrium geometry, and 1200 for well converged optical properties. Also, the exchange series convergence is related to the band gap. The PBE0 band gap is as small as 1.4 eV and the exchange summation must extend to about 130 Å from the origin cell. Total energy, band gap, equilibrium geometry, polarizability, and second hyperpolarizability of oligomers -(C2H2)m-, with m up to 50 (202 atoms), and of the polymer have been compared. It turns out that oligomers of that length provide an extremely poor representation of the infinite chain polarizability and hyperpolarizability when the gap is smaller than 0.2 eV (that is, for LDA and PBE). Huge differences are observed on αxx and γxxxx of the polymer when different functionals are used, that is in connection to the well-known density functional theory (DFT) overshoot, reported in the literature about short oligomers: for the infinite model the ratio between LDA (or PBE) and HF becomes even more dramatic (about 500 for αxx and 1010 for γxxxx). On the basis of previous systematic comparisons of results obtained with various approaches including DFT, HF, Moller-Plesset (MP2) and coupled cluster for finite chains, we can argue that, for the infinite chain, the present HF results are the most reliable.

Scalable Computing of the Mesh Size Effect on Modeling Damage Mechanics in Woven Armor Composites

DTIC Science & Technology

2008-12-01

manner of a user defined material subroutine to provide overall stress increments to, the parallel LS-DYNA3D a Lagrangian explicit code used in...finite element code, as a user defined material subroutine . The ability of this subroutine to model the effect of the progressions of a select number...is added as a user defined material subroutine to parallel LS-DYNA3D. The computations of the global mesh are handled by LS-DYNA3D and are spread

Riemann-Hilbert technique scattering analysis of metamaterial-based asymmetric 2D open resonators

NASA Astrophysics Data System (ADS)

Kamiński, Piotr M.; Ziolkowski, Richard W.; Arslanagić, Samel

2017-12-01

The scattering properties of metamaterial-based asymmetric two-dimensional open resonators excited by an electric line source are investigated analytically. The resonators are, in general, composed of two infinite and concentric cylindrical layers covered with an infinitely thin, perfect conducting shell that has an infinite axial aperture. The line source is oriented parallel to the cylinder axis. An exact analytical solution of this problem is derived. It is based on the dual-series approach and its transformation to the equivalent Riemann-Hilbert problem. Asymmetric metamaterial-based configurations are found to lead simultaneously to large enhancements of the radiated power and to highly steerable Huygens-like directivity patterns; properties not attainable with the corresponding structurally symmetric resonators. The presented open resonator designs are thus interesting candidates for many scientific and engineering applications where enhanced directional near- and far-field responses, tailored with beam shaping and steering capabilities, are highly desired.

Cooperativity of halogen, chalcogen, and pnictogen bonds in infinite molecular chains by electronic structure theory.

PubMed

George, Janine; Deringer, Volker L; Dronskowski, Richard

2014-05-01

Halogen bonds (XBs) are intriguing noncovalent interactions that are frequently being exploited for crystal engineering. Recently, similar bonding mechanisms have been proposed for adjacent main-group elements, and noncovalent "chalcogen bonds" and "pnictogen bonds" have been identified in crystal structures. A fundamental question, largely unresolved thus far, is how XBs and related contacts interact with each other in crystals; similar to hydrogen bonding, one might expect "cooperativity" (bonds amplifying each other), but evidence has been sparse. Here, we explore the crucial step from gas-phase oligomers to truly infinite chains by means of quantum chemical computations. A periodic density functional theory (DFT) framework allows us to address polymeric chains of molecules avoiding the dreaded "cluster effects" as well as the arbitrariness of defining a "large enough" cluster. We focus on three types of molecular chains that we cut from crystal structures; furthermore, we explore reasonable substitutional variants in silico. We find evidence of cooperativity in chains of halogen cyanides and also in similar chalcogen- and pnictogen-bonded systems; the bonds, in the most extreme cases, are amplified through cooperative effects by 79% (I···N), 90% (Te···N), and 103% (Sb···N). Two experimentally known organic crystals, albeit with similar atomic connectivity and XB characteristics, show signs of cooperativity in one case but not in another. Finally, no cooperativity is observed in alternating halogen/acetone and halogen/1,4-dioxane chains; in fact, these XBs weaken each other by up to 26% compared to the respective gas-phase dimers.

A Comparison of Numerical and Analytical Radiative-Transfer Solutions for Plane Albedo of Natural Waters

EPA Science Inventory

Three numerical algorithms were compared to provide a solution of a radiative transfer equation (RTE) for plane albedo (hemispherical reflectance) in semi-infinite one-dimensional plane-parallel layer. Algorithms were based on the invariant imbedding method and two different var...

Multiple scattering by infinitely long cylindrical glass inclusions in a saturated Biot porous medium of glass beads.

PubMed

Trabelsi, W; Franklin, H; Tinel, A

2016-05-01

The resonance spectrum of sets of two to five infinitely long parallel cylindrical glass inclusions in a fluid saturated porous matrix of unconsolidated glass beads is investigated. The ratio of bead diameters to inclusion diameters is 1/5. The far field form functions and the related phase derivatives are calculated by using an exact multiple scattering formalism and by assuming that the porous medium obeys Biot's model. In order to validate this hypothesis, comparisons between theory and experiments are done in the special case of a fast incident wave on a set of two and three inclusions.

Numerical experiments with flows of elongated granules

NASA Technical Reports Server (NTRS)

Elrod, Harold G.; Brewe, David E.

1992-01-01

Theory and numerical results are given for a program simulating two dimensional granular flow (1) between two infinite, counter-moving, parallel, roughened walls, and (2) for an infinitely wide slider. Each granule is simulated by a central repulsive force field ratcheted with force restitution factor to introduce dissipation. Transmission of angular momentum between particles occurs via Coulomb friction. The effect of granular hardness is explored. Gaps from 7 to 28 particle diameters are investigated, with solid fractions ranging from 0.2 to 0.9. Among features observed are: slip flow at boundaries, coagulation at high densities, and gross fluctuation in surface stress. A videotape has been prepared to demonstrate the foregoing effects.

Comparison of infinite and wedge fringe settings in Mach Zehnder interferometer for temperature field measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haridas, Divya; P, Vibin Antony; Sajith, V.

2014-10-15

Interferometric method, which utilizes the interference of coherent light beams, is used to determine the temperature distribution in the vicinity of a vertical heater plate. The optical components are arranged so as to obtain wedge fringe and infinite fringe patterns and isotherms obtained in each case were compared. In wedge fringe setting, image processing techniques has been used for obtaining isotherms by digital subtraction of initial parallel fringe pattern from deformed fringe pattern. The experimental results obtained are compared with theoretical correlations. The merits and demerits of the fringe analysis techniques are discussed on the basis of the experimental results.

Density matrix renormalization group for a highly degenerate quantum system: Sliding environment block approach

NASA Astrophysics Data System (ADS)

Schmitteckert, Peter

2018-04-01

We present an infinite lattice density matrix renormalization group sweeping procedure which can be used as a replacement for the standard infinite lattice blocking schemes. Although the scheme is generally applicable to any system, its main advantages are the correct representation of commensurability issues and the treatment of degenerate systems. As an example we apply the method to a spin chain featuring a highly degenerate ground-state space where the new sweeping scheme provides an increase in performance as well as accuracy by many orders of magnitude compared to a recently published work.

Alternating currents and shear waves in viscous electronics

NASA Astrophysics Data System (ADS)

Semenyakin, M.; Falkovich, G.

2018-02-01

Strong interaction among charge carriers can make them move like viscous fluid. Here we explore alternating current (ac) effects in viscous electronics. In the Ohmic case, incompressible current distribution in a sample adjusts fast to a time-dependent voltage on the electrodes, while in the viscous case, momentum diffusion makes for retardation and for the possibility of propagating slow shear waves. We focus on specific geometries that showcase interesting aspects of such waves: current parallel to a one-dimensional defect and current applied across a long strip. We find that the phase velocity of the wave propagating along the strip respectively increases/decreases with the frequency for no-slip/no-stress boundary conditions. This is so because when the frequency or strip width goes to zero (alternatively, viscosity go to infinity), the wavelength of the current pattern tends to infinity in the no-stress case and to a finite value in a general case. We also show that for dc current across a strip with a no-stress boundary, there are only one pair of vortices, while there is an infinite vortex chain for all other types of boundary conditions.

La 1–xBi 1+xS 3 ( x ≈ 0.08): An n-Type Semiconductor

DOE PAGES

Han, Fei; Liu, Huimei; Malliakas, Christos D.; ...

2016-03-21

We study the new bismuth chalcogenide La 0.92Bi 1.08S 3 which crystallizes in the monoclinic space group C2/m with a = 28.0447(19) Å, b = 4.0722(2) Å, c = 14.7350(9) Å, and β = 118.493(5)°. The structure of La 0.92Bi 1.08S 3 is built of NaCl-type Bi 2S 5 blocks and BiS 4 and LaS 5 infinitely long chains, forming a compact three-dimensional framework with parallel tunnels. Optical spectroscopy and resistivity measurements reveal a semiconducting behavior with a band gap of ~1 eV and activation energy for transport of 0.36(1) eV. Thermopower measurements suggest the majority carriers of La 0.92Bimore » 1.08S 3 are electrons. Heat capacity measurements indicate no phase transitions from 2 to 300 K. Lastly, band structure calculations at the density functional theory level confirm the semiconducting nature and the indirect gap of La 0.92Bi 1.08S 3.« less

β-Li0.37Na0.63Fe(MoO4)2

PubMed Central

Souilem, Amira; Zid, Mohamed Faouzi; Driss, Ahmed

2014-01-01

The title compound, lithium/sodium iron(III) bis­[ortho­molyb­date(VI)], was obtained by a solid-state reaction. The main structure units are an FeO6 octa­hedron, a distorted MoO6 octa­hedron and an MoO4 tetra­hedron sharing corners. The crystal structure is composed of infinite double MoFeO11 chains along the b-axis direction linked by corner-sharing to MoO4 tetra­hedra so as to form Fe2Mo3O19 ribbons. The cohesion between ribbons via mixed Mo—O—Fe bridges leads to layers arranged parallel to the bc plane. Adjacent layers are linked by corners shared between MoO4 tetra­hedra of one layer and FeO6 octa­hedra of the other layer. The Na+ and Li+ ions partially occupy the same general position, with a site-occupancy ratio of 0.631 (9):0.369 (1). A comparison is made with AFe(MoO4)2 (A = Li, Na, K and Cs) structures. PMID:24764805

Anomalous dynamical phase in quantum spin chains with long-range interactions

NASA Astrophysics Data System (ADS)

Homrighausen, Ingo; Abeling, Nils O.; Zauner-Stauber, Valentin; Halimeh, Jad C.

2017-09-01

The existence or absence of nonanalytic cusps in the Loschmidt-echo return rate is traditionally employed to distinguish between a regular dynamical phase (regular cusps) and a trivial phase (no cusps) in quantum spin chains after a global quench. However, numerical evidence in a recent study (J. C. Halimeh and V. Zauner-Stauber, arXiv:1610.02019) suggests that instead of the trivial phase, a distinct anomalous dynamical phase characterized by a novel type of nonanalytic cusps occurs in the one-dimensional transverse-field Ising model when interactions are sufficiently long range. Using an analytic semiclassical approach and exact diagonalization, we show that this anomalous phase also arises in the fully connected case of infinite-range interactions, and we discuss its defining signature. Our results show that the transition from the regular to the anomalous dynamical phase coincides with Z2-symmetry breaking in the infinite-time limit, thereby showing a connection between two different concepts of dynamical criticality. Our work further expands the dynamical phase diagram of long-range interacting quantum spin chains, and can be tested experimentally in ion-trap setups and ultracold atoms in optical cavities, where interactions are inherently long range.

Magneto-elastic modeling of composites containing chain-structured magnetostrictive particles

NASA Astrophysics Data System (ADS)

Yin, H. M.; Sun, L. Z.; Chen, J. S.

2006-05-01

Magneto-elastic behavior is investigated for two-phase composites containing chain-structured magnetostrictive particles under both magnetic and mechanical loading. To derive the local magnetic and elastic fields, three modified Green's functions are derived and explicitly integrated for the infinite domain containing a spherical inclusion with a prescribed magnetization, body force, and eigenstrain. A representative volume element containing a chain of infinite particles is introduced to solve averaged magnetic and elastic fields in the particles and the matrix. Effective magnetostriction of composites is derived by considering the particle's magnetostriction and the magnetic interaction force. It is shown that there exists an optimal choice of the Young's modulus of the matrix and the volume fraction of the particles to achieve the maximum effective magnetostriction. A transversely isotropic effective elasticity is derived at the infinitesimal deformation. Disregarding the interaction term, this model provides the same effective elasticity as Mori-Tanaka's model. Comparisons of model results with the experimental data and other models show the efficacy of the model and suggest that the particle interactions have a considerable effect on the effective magneto-elastic properties of composites even for a low particle volume fraction.

A Comparison of Numerical and Analytical Radiative-Transfer Solutions for Plane Albedo in Natural Waters

EPA Science Inventory

Several numerical and analytical solutions of the radiative transfer equation (RTE) for plane albedo were compared for solar light reflection by sea water. The study incorporated the simplest case, that being a semi-infinite one-dimensional plane-parallel absorbing and scattering...

Improved packing of protein side chains with parallel ant colonies.

PubMed

Quan, Lijun; Lü, Qiang; Li, Haiou; Xia, Xiaoyan; Wu, Hongjie

2014-01-01

The accurate packing of protein side chains is important for many computational biology problems, such as ab initio protein structure prediction, homology modelling, and protein design and ligand docking applications. Many of existing solutions are modelled as a computational optimisation problem. As well as the design of search algorithms, most solutions suffer from an inaccurate energy function for judging whether a prediction is good or bad. Even if the search has found the lowest energy, there is no certainty of obtaining the protein structures with correct side chains. We present a side-chain modelling method, pacoPacker, which uses a parallel ant colony optimisation strategy based on sharing a single pheromone matrix. This parallel approach combines different sources of energy functions and generates protein side-chain conformations with the lowest energies jointly determined by the various energy functions. We further optimised the selected rotamers to construct subrotamer by rotamer minimisation, which reasonably improved the discreteness of the rotamer library. We focused on improving the accuracy of side-chain conformation prediction. For a testing set of 442 proteins, 87.19% of X1 and 77.11% of X12 angles were predicted correctly within 40° of the X-ray positions. We compared the accuracy of pacoPacker with state-of-the-art methods, such as CIS-RR and SCWRL4. We analysed the results from different perspectives, in terms of protein chain and individual residues. In this comprehensive benchmark testing, 51.5% of proteins within a length of 400 amino acids predicted by pacoPacker were superior to the results of CIS-RR and SCWRL4 simultaneously. Finally, we also showed the advantage of using the subrotamers strategy. All results confirmed that our parallel approach is competitive to state-of-the-art solutions for packing side chains. This parallel approach combines various sources of searching intelligence and energy functions to pack protein side chains. It provides a frame-work for combining different inaccuracy/usefulness objective functions by designing parallel heuristic search algorithms.

Partitioning problems in parallel, pipelined and distributed computing

NASA Technical Reports Server (NTRS)

Bokhari, S.

1985-01-01

The problem of optimally assigning the modules of a parallel program over the processors of a multiple computer system is addressed. A Sum-Bottleneck path algorithm is developed that permits the efficient solution of many variants of this problem under some constraints on the structure of the partitions. In particular, the following problems are solved optimally for a single-host, multiple satellite system: partitioning multiple chain structured parallel programs, multiple arbitrarily structured serial programs and single tree structured parallel programs. In addition, the problems of partitioning chain structured parallel programs across chain connected systems and across shared memory (or shared bus) systems are also solved under certain constraints. All solutions for parallel programs are equally applicable to pipelined programs. These results extend prior research in this area by explicitly taking concurrency into account and permit the efficient utilization of multiple computer architectures for a wide range of problems of practical interest.

Self-dual gravity is completely integrable

NASA Astrophysics Data System (ADS)

Nutku, Y.; Sheftel, M. B.; Kalayci, J.; Yazıcı, D.

2008-10-01

We discover a multi-Hamiltonian structure of a complex Monge-Ampère equation (CMA) set in a real first-order 2-component form. Therefore, by Magri's theorem this is a completely integrable system in four real dimensions. We start with Lagrangian and Hamiltonian densities and obtain a symplectic form and the Hamiltonian operator that determines the Dirac bracket. We have calculated all point symmetries of the 2-component CMA system and Hamiltonians of the symmetry flows. We have found two new real recursion operators for symmetries which commute with the operator of a symmetry condition on solutions of the CMA system. These operators form two Lax pairs for the 2-component system. The recursion operators, applied to the first Hamiltonian operator, generate infinitely many real Hamiltonian structures. We show how to construct an infinite hierarchy of higher commuting flows together with the corresponding infinite chain of their Hamiltonians.

Synthesis, structure, and physicochemical investigations of the new α Cu 0.50TiO(PO 4) oxyphosphate

NASA Astrophysics Data System (ADS)

Benmokhtar, S.; Belmal, H.; El Jazouli, A.; Chaminade, J. P.; Gravereau, P.; Pechev, S.; Grenier, J. C.; Villeneuve, G.; de Waal, D.

2007-02-01

The room-temperature crystal structure of a new Cu(II) oxyphosphate— α Cu 0.50IITiO(PO 4)—was determined from X-ray single crystals diffraction data, in the monoclinic system, space group P2 1/c. The refinement from 5561 independent reflections lead to the following parameters: a=7.5612(4)Å, b=7.0919(4)Å, c=7.4874(4)Å, β=122.25(1)°, Z=4, with the final R=0.0198, wR=0.0510. The structure of α Cu 0.50IITiO(PO 4) can be described as a TiOPO 4 framework constituted by chains of tilted corner-sharing [TiO 6] octahedra running parallel to the c-axis and cross linked by phosphate [PO 4] tetrahedra, where one-half of octahedral cavities created are occupied by Cu atoms. Ti atoms are displaced from the center of octahedra units in alternating long (2.308 Å) and short (1.722 Å) Ti-O(1) bonds along chains. Such O(1) atoms not linked to P atoms justify the oxyphosphate formulation α Cu 0.50TiO(PO 4). The divalent cations Cu 2+ occupy a Jahn-Teller distorted octahedron sharing two faces with two [TiO 6] octahedra. EPR and optical measurements are in good agreement with structural data. The X-ray diffraction results are supported by Raman and infrared spectroscopy studies that confirmed the existence of the infinite chains -Ti-O-Ti-O-Ti-. α Cu 0.50TiO(PO 4) shows a Curie-Weiss paramagnetic behavior in the temperature range 4-80 K.

Chain-reaction crash on a highway in high visibility

NASA Astrophysics Data System (ADS)

Nagatani, Takashi

2016-05-01

We study the chain-reaction crash (multiple-vehicle collision) in high-visibility condition on a highway. In the traffic situation, drivers control their vehicles by both gear-changing and braking. Drivers change the gears according to the headway and brake according to taillights of the forward vehicle. We investigate whether or not the first collision induces the chain-reaction crash numerically. It is shown that dynamic transitions occur from no collisions, through a single collision, to multiple collisions with decreasing the headway. Also, we find that the dynamic transition occurs from the finite chain reaction to the infinite chain reaction when the headway is less than the critical value. We compare the multiple-vehicle collisions in high-visibility with that in low-visibility. We derive the transition points and the region maps for the chain-reaction crash in high visibility.

The Nature of Bonding in Bulk Tellurium Composed of One-Dimensional Helical Chains.

PubMed

Yi, Seho; Zhu, Zhili; Cai, Xiaolin; Jia, Yu; Cho, Jun-Hyung

2018-05-07

Bulk tellurium (Te) is composed of one-dimensional (1D) helical chains which have been considered to be coupled by van der Waals (vdW) interactions. However, on the basis of first-principles density functional theory calculations, we here propose a different bonding nature between neighboring chains: i.e., helical chains made of normal covalent bonds are connected together by coordinate covalent bonds. It is revealed that the lone pairs of electrons of Te atoms participate in forming coordinate covalent bonds between neighboring chains, where each Te atom behaves as both an electron donor to neighboring chains and an electron acceptor from neighboring chains. This ligand-metal-like bonding nature in bulk Te results in the same order of bulk moduli along the directions parallel and perpendicular to the chains, contrasting with the large anisotropy of bulk moduli in vdW crystals. We further find that the electron effective masses parallel and perpendicular to the chains are almost the same as each other, consistent with the observed nearly isotropic electrical resistivity. It is thus demonstrated that the normal/coordinate covalent bonds parallel/perpendicular to the chains in bulk Te lead to a minor anisotropy in structural and transport properties.

Grid-free density functional calculations on periodic systems.

PubMed

Varga, Stefan

2007-09-21

Density fitting scheme is applied to the exchange part of the Kohn-Sham potential matrix in a grid-free local density approximation for infinite systems with translational periodicity. It is shown that within this approach the computational demands for the exchange part scale in the same way as for the Coulomb part. The efficiency of the scheme is demonstrated on a model infinite polymer chain. For simplicity, the implementation with Dirac-Slater Xalpha exchange functional is presented only. Several choices of auxiliary basis set expansion coefficients were tested with both Coulomb and overlap metric. Their effectiveness is discussed also in terms of robustness and norm preservation.

Grid-free density functional calculations on periodic systems

NASA Astrophysics Data System (ADS)

Varga, Štefan

2007-09-01

Density fitting scheme is applied to the exchange part of the Kohn-Sham potential matrix in a grid-free local density approximation for infinite systems with translational periodicity. It is shown that within this approach the computational demands for the exchange part scale in the same way as for the Coulomb part. The efficiency of the scheme is demonstrated on a model infinite polymer chain. For simplicity, the implementation with Dirac-Slater Xα exchange functional is presented only. Several choices of auxiliary basis set expansion coefficients were tested with both Coulomb and overlap metric. Their effectiveness is discussed also in terms of robustness and norm preservation.

Propagation of SH waves in an infinite/semi-infinite piezoelectric/piezomagnetic periodically layered structure.

PubMed

Pang, Yu; Liu, Yu-Shan; Liu, Jin-Xi; Feng, Wen-Jie

2016-04-01

In this paper, SH bulk/surface waves propagating in the corresponding infinite/semi-infinite piezoelectric (PE)/piezomagnetic (PM) and PM/PE periodically layered composites are investigated by two methods, the stiffness matrix method and the transfer matrix method. For a semi-infinite PE/PM or PM/PE medium, the free surface is parallel to the layer interface. Both PE and PM materials are assumed to be transversely isotropic solids. Dispersion equations are derived by the stiffness/transfer matrix methods, respectively. The effects of electric-magnetic (ME) boundary conditions at the free surface and the layer thickness ratios on dispersion curves are considered in detail. Numerical examples show that the results calculated by the two methods are the same. The dispersion curves of SH surface waves are below the bulk bands or inside the frequency gaps. The ratio of the layer thickness has an important effect not only on the bulk bands but also on the dispersion curves of SH surface waves. Electric and magnetic boundary conditions, respectively, determine the dispersion curves of SH surface waves for the PE/PM and PM/PE semi-infinite structures. The band structures of SH bulk waves are consistent for the PE/PM and PM/PE structures, however, the dispersive behaviors of SH surface waves are indeed different for the two composites. The realization of the above-mentioned characteristics of SH waves will make it possible to design PE/PM acoustic wave devices with periodical structures and achieve the better performance. Copyright © 2016 Elsevier B.V. All rights reserved.

Thin-Film Nanocapacitor and Its Characterization

ERIC Educational Resources Information Center

Hunter, David N.; Pickering, Shawn L.; Jia, Dongdong

2007-01-01

An undergraduate thin-film nanotechnology laboratory was designed. Nanocapacitors were fabricated on silicon substrates by sputter deposition. A mask was designed to form the shape of the capacitor and its electrodes. Thin metal layers of Au with a 80 nm thickness were deposited and used as two infinitely large parallel plates for a capacitor.…

Interuniversal entanglement in a cyclic multiverse

NASA Astrophysics Data System (ADS)

Robles-Pérez, Salvador; Balcerzak, Adam; Dąbrowski, Mariusz P.; Krämer, Manuel

2017-04-01

We study scenarios of parallel cyclic multiverses which allow for a different evolution of the physical constants, while having the same geometry. These universes are classically disconnected, but quantum-mechanically entangled. Applying the thermodynamics of entanglement, we calculate the temperature and the entropy of entanglement. It emerges that the entropy of entanglement is large at big bang and big crunch singularities of the parallel universes as well as at the maxima of the expansion of these universes. The latter seems to confirm earlier studies that quantum effects are strong at turning points of the evolution of the universe performed in the context of the timeless nature of the Wheeler-DeWitt equation and decoherence. On the other hand, the entropy of entanglement at big rip singularities is going to zero despite its presumably quantum nature. This may be an effect of total dissociation of the universe structures into infinitely separated patches violating the null energy condition. However, the temperature of entanglement is large/infinite at every classically singular point and at maximum expansion and seems to be a better measure of quantumness.

Calculation of longitudinal polarizability and second hyperpolarizability of polyacetylene with the coupled perturbed Hartree-Fock/Kohn-Sham scheme: where it is shown how finite oligomer chains tend to the infinite periodic polymer.

PubMed

Lacivita, Valentina; Rèrat, Michel; Orlando, Roberto; Ferrero, Mauro; Dovesi, Roberto

2012-03-21

The longitudinal polarizability, α(xx), and second hyperpolarizability, γ(xxxx), of polyacetylene are evaluated by using the coupled perturbed Hartree-Fock/Kohn-Sham (HF/KS) scheme as implemented in the periodic CRYSTAL code and a split valence type basis set. Four different density functionals, namely local density approximation (LDA) (pure local), Perdew-Becke-Ernzerhof (PBE) (gradient corrected), PBE0, and B3LYP (hybrid), and the Hartree-Fock Hamiltonian are compared. It is shown that very tight computational conditions must be used to obtain well converged results, especially for γ(xxxx), that is, very sensitive to the number of k(->) points in reciprocal space when the band gap is small (as for LDA and PBE), and to the extension of summations of the exact exchange series (HF and hybrids). The band gap in LDA is only 0.01 eV: at least 300 k(->) points are required to obtain well converged total energy and equilibrium geometry, and 1200 for well converged optical properties. Also, the exchange series convergence is related to the band gap. The PBE0 band gap is as small as 1.4 eV and the exchange summation must extend to about 130 Å from the origin cell. Total energy, band gap, equilibrium geometry, polarizability, and second hyperpolarizability of oligomers -(C(2)H(2))(m)-, with m up to 50 (202 atoms), and of the polymer have been compared. It turns out that oligomers of that length provide an extremely poor representation of the infinite chain polarizability and hyperpolarizability when the gap is smaller than 0.2 eV (that is, for LDA and PBE). Huge differences are observed on α(xx) and γ(xxxx) of the polymer when different functionals are used, that is in connection to the well-known density functional theory (DFT) overshoot, reported in the literature about short oligomers: for the infinite model the ratio between LDA (or PBE) and HF becomes even more dramatic (about 500 for α(xx) and 10(10) for γ(xxxx)). On the basis of previous systematic comparisons of results obtained with various approaches including DFT, HF, Moller-Plesset (MP2) and coupled cluster for finite chains, we can argue that, for the infinite chain, the present HF results are the most reliable. © 2012 American Institute of Physics

Structural study and physical properties of a new phosphate KCuFe(PO 4) 2

NASA Astrophysics Data System (ADS)

Badri, Abdessalem; Hidouri, Mourad; López, María Luisa; Pico, Carlos; Wattiaux, Alain; Amara, Mongi Ben

2011-04-01

Single crystals of a new phosphate KCuFe(PO 4) 2 have been prepared by the flux method and its structural and physical properties have been investigated. This compound crystallizes in the monoclinic system with the space group P2 1/ n and its parameters are: a=7.958(3) Å, b=9.931(2) Å, c=9.039(2) Å, β=115.59(3)° and Z=4. Its structure consists of FeO 6 octahedra sharing corners with Cu 2O 8 units of edge-sharing CuO 5 polyhedra to form undulating chains extending infinitely along the b-axis. These chains are connected by the phosphate tetrahedra giving rise to a 3D framework with six-sided tunnels parallel to the [101] direction, where the K + ions are located. The Mössbauer spectroscopy results confirm the exclusive presence of octahedral Fe 3+ ions. The magnetic measurements show the compound to be antiferromagnetic with Cm=5.71 emu K/mol and θ=-156.5 K. The derived experimental effective moment μex=6.76 μB is somewhat higher than the theoretical one of μth=6.16 μB, calculated taking only into account the spin contribution for Fe 3+ and Cu 2+ cations. Electrical measurements allow us to obtain the activation energy (1.22 eV) and the conductivity measurements suggest that the charge carriers through the structure are the potassium cations.

Improved packing of protein side chains with parallel ant colonies

PubMed Central

2014-01-01

Introduction The accurate packing of protein side chains is important for many computational biology problems, such as ab initio protein structure prediction, homology modelling, and protein design and ligand docking applications. Many of existing solutions are modelled as a computational optimisation problem. As well as the design of search algorithms, most solutions suffer from an inaccurate energy function for judging whether a prediction is good or bad. Even if the search has found the lowest energy, there is no certainty of obtaining the protein structures with correct side chains. Methods We present a side-chain modelling method, pacoPacker, which uses a parallel ant colony optimisation strategy based on sharing a single pheromone matrix. This parallel approach combines different sources of energy functions and generates protein side-chain conformations with the lowest energies jointly determined by the various energy functions. We further optimised the selected rotamers to construct subrotamer by rotamer minimisation, which reasonably improved the discreteness of the rotamer library. Results We focused on improving the accuracy of side-chain conformation prediction. For a testing set of 442 proteins, 87.19% of X1 and 77.11% of X12 angles were predicted correctly within 40° of the X-ray positions. We compared the accuracy of pacoPacker with state-of-the-art methods, such as CIS-RR and SCWRL4. We analysed the results from different perspectives, in terms of protein chain and individual residues. In this comprehensive benchmark testing, 51.5% of proteins within a length of 400 amino acids predicted by pacoPacker were superior to the results of CIS-RR and SCWRL4 simultaneously. Finally, we also showed the advantage of using the subrotamers strategy. All results confirmed that our parallel approach is competitive to state-of-the-art solutions for packing side chains. Conclusions This parallel approach combines various sources of searching intelligence and energy functions to pack protein side chains. It provides a frame-work for combining different inaccuracy/usefulness objective functions by designing parallel heuristic search algorithms. PMID:25474164

A time scheduling model of logistics service supply chain based on the customer order decoupling point: a perspective from the constant service operation time.

PubMed

Liu, Weihua; Yang, Yi; Xu, Haitao; Liu, Xiaoyan; Wang, Yijia; Liang, Zhicheng

2014-01-01

In mass customization logistics service, reasonable scheduling of the logistics service supply chain (LSSC), especially time scheduling, is benefit to increase its competitiveness. Therefore, the effect of a customer order decoupling point (CODP) on the time scheduling performance should be considered. To minimize the total order operation cost of the LSSC, minimize the difference between the expected and actual time of completing the service orders, and maximize the satisfaction of functional logistics service providers, this study establishes an LSSC time scheduling model based on the CODP. Matlab 7.8 software is used in the numerical analysis for a specific example. Results show that the order completion time of the LSSC can be delayed or be ahead of schedule but cannot be infinitely advanced or infinitely delayed. Obtaining the optimal comprehensive performance can be effective if the expected order completion time is appropriately delayed. The increase in supply chain comprehensive performance caused by the increase in the relationship coefficient of logistics service integrator (LSI) is limited. The relative concern degree of LSI on cost and service delivery punctuality leads to not only changes in CODP but also to those in the scheduling performance of the LSSC.

A Time Scheduling Model of Logistics Service Supply Chain Based on the Customer Order Decoupling Point: A Perspective from the Constant Service Operation Time

PubMed Central

Yang, Yi; Xu, Haitao; Liu, Xiaoyan; Wang, Yijia; Liang, Zhicheng

2014-01-01

In mass customization logistics service, reasonable scheduling of the logistics service supply chain (LSSC), especially time scheduling, is benefit to increase its competitiveness. Therefore, the effect of a customer order decoupling point (CODP) on the time scheduling performance should be considered. To minimize the total order operation cost of the LSSC, minimize the difference between the expected and actual time of completing the service orders, and maximize the satisfaction of functional logistics service providers, this study establishes an LSSC time scheduling model based on the CODP. Matlab 7.8 software is used in the numerical analysis for a specific example. Results show that the order completion time of the LSSC can be delayed or be ahead of schedule but cannot be infinitely advanced or infinitely delayed. Obtaining the optimal comprehensive performance can be effective if the expected order completion time is appropriately delayed. The increase in supply chain comprehensive performance caused by the increase in the relationship coefficient of logistics service integrator (LSI) is limited. The relative concern degree of LSI on cost and service delivery punctuality leads to not only changes in CODP but also to those in the scheduling performance of the LSSC. PMID:24715818

Many-body localization in Ising models with random long-range interactions

NASA Astrophysics Data System (ADS)

Li, Haoyuan; Wang, Jia; Liu, Xia-Ji; Hu, Hui

2016-12-01

We theoretically investigate the many-body localization phase transition in a one-dimensional Ising spin chain with random long-range spin-spin interactions, Vi j∝|i-j |-α , where the exponent of the interaction range α can be tuned from zero to infinitely large. By using exact diagonalization, we calculate the half-chain entanglement entropy and the energy spectral statistics and use them to characterize the phase transition towards the many-body localization phase at infinite temperature and at sufficiently large disorder strength. We perform finite-size scaling to extract the critical disorder strength and the critical exponent of the divergent localization length. With increasing α , the critical exponent experiences a sharp increase at about αc≃1.2 and then gradually decreases to a value found earlier in a disordered short-ranged interacting spin chain. For α <αc , we find that the system is mostly localized and the increase in the disorder strength may drive a transition between two many-body localized phases. In contrast, for α >αc , the transition is from a thermalized phase to the many-body localization phase. Our predictions could be experimentally tested with an ion-trap quantum emulator with programmable random long-range interactions, or with randomly distributed Rydberg atoms or polar molecules in lattices.

Parallelization of the TRIGRS model for rainfall-induced landslides using the message passing interface

USGS Publications Warehouse

Alvioli, M.; Baum, R.L.

2016-01-01

We describe a parallel implementation of TRIGRS, the Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Model for the timing and distribution of rainfall-induced shallow landslides. We have parallelized the four time-demanding execution modes of TRIGRS, namely both the saturated and unsaturated model with finite and infinite soil depth options, within the Message Passing Interface framework. In addition to new features of the code, we outline details of the parallel implementation and show the performance gain with respect to the serial code. Results are obtained both on commercial hardware and on a high-performance multi-node machine, showing the different limits of applicability of the new code. We also discuss the implications for the application of the model on large-scale areas and as a tool for real-time landslide hazard monitoring.

3D printed soft parallel actuator

NASA Astrophysics Data System (ADS)

Zolfagharian, Ali; Kouzani, Abbas Z.; Khoo, Sui Yang; Noshadi, Amin; Kaynak, Akif

2018-04-01

This paper presents a 3-dimensional (3D) printed soft parallel contactless actuator for the first time. The actuator involves an electro-responsive parallel mechanism made of two segments namely active chain and passive chain both 3D printed. The active chain is attached to the ground from one end and constitutes two actuator links made of responsive hydrogel. The passive chain, on the other hand, is attached to the active chain from one end and consists of two rigid links made of polymer. The actuator links are printed using an extrusion-based 3D-Bioplotter with polyelectrolyte hydrogel as printer ink. The rigid links are also printed by a 3D fused deposition modelling (FDM) printer with acrylonitrile butadiene styrene (ABS) as print material. The kinematics model of the soft parallel actuator is derived via transformation matrices notations to simulate and determine the workspace of the actuator. The printed soft parallel actuator is then immersed into NaOH solution with specific voltage applied to it via two contactless electrodes. The experimental data is then collected and used to develop a parametric model to estimate the end-effector position and regulate kinematics model in response to specific input voltage over time. It is observed that the electroactive actuator demonstrates expected behaviour according to the simulation of its kinematics model. The use of 3D printing for the fabrication of parallel soft actuators opens a new chapter in manufacturing sophisticated soft actuators with high dexterity and mechanical robustness for biomedical applications such as cell manipulation and drug release.

New Factorization Techniques and Parallel (log N) Algorithms for Forward Dynamics Solution of Single Closed-Chain Robot Manipulators

NASA Technical Reports Server (NTRS)

Fijany, Amir

1993-01-01

In this paper parallel 0(log N) algorithms for dynamic simulation of single closed-chain rigid multibody system as specialized to the case of a robot manipulatoar in contact with the environment are developed.

Hall effects on unsteady MHD reactive flow of second grade fluid through porous medium in a rotating parallel plate channel

NASA Astrophysics Data System (ADS)

Krishna, M. Veera; Swarnalathamma, B. V.

2017-07-01

We considered the transient MHD flow of a reactive second grade fluid through porous medium between two infinitely long horizontal parallel plates when one of the plate is set into uniform accelerated motion in the presence of a uniform transverse magnetic field under Arrhenius reaction rate. The governing equations are solved by Laplace transform technique. The effects of the pertinent parameters on the velocity, temperature are discussed in detail. The shear stress and Nusselt number at the plates are also obtained analytically and computationally discussed with reference to governing parameters.

Lunar electromagnetic scattering. 1: Propagation parallel to the diamagnetic cavity axis

NASA Technical Reports Server (NTRS)

Schwartz, K.; Schubert, G.

1972-01-01

An analytic theory is developed for the time dependent magnetic fields inside the Moon and the diamagnetic cavity when the interplanetary electromagnetic field fluctuation propagates parallel to the cavity axis. The Moon model has an electrical conductivity which is an arbitrary function of radius. The lunar cavity is modelled by a nonconducting cylinder extending infinitely far downstream. For frequencies less than about 50 Hz, the cavity is a cylindrical waveguide below cutoff. Thus, cavity field perturbations due to the Moon do not propagate down the cavity, but are instead attenuated with distance downstream from the Moon.

How can we make stable linear monoatomic chains? Gold-cesium binary subnanowires as an example of a charge-transfer-driven approach to alloying.

PubMed

Choi, Young Cheol; Lee, Han Myoung; Kim, Woo Youn; Kwon, S K; Nautiyal, Tashi; Cheng, Da-Yong; Vishwanathan, K; Kim, Kwang S

2007-02-16

On the basis of first-principles calculations of clusters and one dimensional infinitely long subnanowires of the binary systems, we find that alkali-noble metal alloy wires show better linearity and stability than either pure alkali metal or noble metal wires. The enhanced alternating charge buildup on atoms by charge transfer helps the atoms line up straight. The cesium doped gold wires showing significant charge transfer from cesium to gold can be stabilized as linear or circular monoatomic chains.

Linear-to-λ-Shape P-O-P Bond Transmutation in Polyphosphates with Infinite (PO3)∞ Chain.

PubMed

Wang, Ying; Li, Lin; Han, Shujuan; Lei, Bing-Hua; Abudoureheman, Maierhaba; Yang, Zhihua; Pan, Shilie

2017-09-05

A new metal polyphosphate, α-CsBa 2 (PO 3 ) 5 , exhibiting the first example of a linear P-O-P bond angle in a one-dimensional (PO 3 ) ∞ chain has been reported. Interestingly, α → β phase transition occurs in CsBa 2 (PO 3 ) 5 along with the P-O-P bonds varying from linear to λ-shape, suggesting that α-CsBa 2 (PO 3 ) 5 with unfavorable linear P-O-P bonds is more stable at ambient temperature.

Q-operators for the open Heisenberg spin chain

NASA Astrophysics Data System (ADS)

Frassek, Rouven; Szécsényi, István M.

2015-12-01

We construct Q-operators for the open spin-1/2 XXX Heisenberg spin chain with diagonal boundary matrices. The Q-operators are defined as traces over an infinite-dimensional auxiliary space involving novel types of reflection operators derived from the boundary Yang-Baxter equation. We argue that the Q-operators defined in this way are polynomials in the spectral parameter and show that they commute with transfer matrix. Finally, we prove that the Q-operators satisfy Baxter's TQ-equation and derive the explicit form of their eigenvalues in terms of the Bethe roots.

3-Benzyl­sulfanyl-1H-1,2,4-triazol-5-amine

PubMed Central

Zhang, Shuai; Liu, Pei-Jiang; Ma, Dong-Sheng; Hou, Guang-Feng

2012-01-01

In the title mol­ecule, C9H10N4S, the dihedral angle between the benzene and triazole rings is 81.05 (5)°. In the crystal, N—H⋯N hydrogen bonds link the mol­ecules into infinite zigzag chains along [010]. PMID:22259582

Synthesis and structure determination of La{sub 8}Ti{sub 10}S{sub 24}O{sub 4}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cario, L.; Deudon, C.; Meerschaut, A.

1998-02-15

The new compound La{sub 8}Ti{sub 10}S{sub 24}O{sub 4} has been prepared from a mixture of La{sub 2}Ti{sub 2}O{sub 7} and La{sub 2}O{sub 3} (in a 5:1 ratio) heated at 1,200 C under a H{sub 2}S gas flow. This new quaternary phase was obtained due to an incomplete sulfidizing process. Single-crystal X-ray diffraction studies show that La{sub 8}Ti{sub 10}S{sub 24}O{sub 4} crystallizes in space group P4/mmm, with Z = 1, in a cell of dimensions a = b = 10.421 {angstrom} and c = 8.384 {angstrom}. Least-squares refinement converged to values of R - 0.045 and R{sub w} = 0.048. Themore » structure can be viewed as a stacking of two types of layers along the {rvec c} axis. These layers are built up from infinite rutile-like chains (Ti octahedra) that cross perpendicularly. La atoms, in a tricapped prismatic coordination, are located in tunnels that develop parallel to the {rvec c} direction.« less

Exact mapping between system-reservoir quantum models and semi-infinite discrete chains using orthogonal polynomials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chin, Alex W.; Rivas, Angel; Huelga, Susana F.

2010-09-15

By using the properties of orthogonal polynomials, we present an exact unitary transformation that maps the Hamiltonian of a quantum system coupled linearly to a continuum of bosonic or fermionic modes to a Hamiltonian that describes a one-dimensional chain with only nearest-neighbor interactions. This analytical transformation predicts a simple set of relations between the parameters of the chain and the recurrence coefficients of the orthogonal polynomials used in the transformation and allows the chain parameters to be computed using numerically stable algorithms that have been developed to compute recurrence coefficients. We then prove some general properties of this chain systemmore » for a wide range of spectral functions and give examples drawn from physical systems where exact analytic expressions for the chain properties can be obtained. Crucially, the short-range interactions of the effective chain system permit these open-quantum systems to be efficiently simulated by the density matrix renormalization group methods.« less

Towards the Solution of the Many-Electron Problem in Real Materials: Equation of State of the Hydrogen Chain with State-of-the-Art Many-Body Methods

DOE PAGES

Motta, Mario; Ceperley, David M.; Chan, Garnet Kin-Lic; ...

2017-09-28

We present numerical results for the equation of state of an infinite chain of hydrogen atoms. A variety of modern many-body methods are employed, with exhaustive cross-checks and validation. Approaches for reaching the continuous space limit and the thermodynamic limit are investigated, proposed, and tested. The detailed comparisons provide a benchmark for assessing the current state of the art in many-body computation, and for the development of new methods. The ground-state energy per atom in the linear chain is accurately determined versus bond length, with a confidence bound given on all uncertainties.

Towards the Solution of the Many-Electron Problem in Real Materials: Equation of State of the Hydrogen Chain with State-of-the-Art Many-Body Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Motta, Mario; Ceperley, David M.; Chan, Garnet Kin-Lic

We present numerical results for the equation of state of an infinite chain of hydrogen atoms. A variety of modern many-body methods are employed, with exhaustive cross-checks and validation. Approaches for reaching the continuous space limit and the thermodynamic limit are investigated, proposed, and tested. The detailed comparisons provide a benchmark for assessing the current state of the art in many-body computation, and for the development of new methods. The ground-state energy per atom in the linear chain is accurately determined versus bond length, with a confidence bound given on all uncertainties.

The parallel reaction monitoring method contributes to a highly sensitive polyubiquitin chain quantification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsuchiya, Hikaru; Tanaka, Keiji, E-mail: tanaka-kj@igakuken.or.jp; Saeki, Yasushi, E-mail: saeki-ys@igakuken.or.jp

2013-06-28

Highlights: •The parallel reaction monitoring method was applied to ubiquitin quantification. •The ubiquitin PRM method is highly sensitive even in biological samples. •Using the method, we revealed that Ufd4 assembles the K29-linked ubiquitin chain. -- Abstract: Ubiquitylation is an essential posttranslational protein modification that is implicated in a diverse array of cellular functions. Although cells contain eight structurally distinct types of polyubiquitin chains, detailed function of several chain types including K29-linked chains has remained largely unclear. Current mass spectrometry (MS)-based quantification methods are highly inefficient for low abundant atypical chains, such as K29- and M1-linked chains, in complex mixtures thatmore » typically contain highly abundant proteins. In this study, we applied parallel reaction monitoring (PRM), a quantitative, high-resolution MS method, to quantify ubiquitin chains. The ubiquitin PRM method allows us to quantify 100 attomole amounts of all possible ubiquitin chains in cell extracts. Furthermore, we quantified ubiquitylation levels of ubiquitin-proline-β-galactosidase (Ub-P-βgal), a historically known model substrate of the ubiquitin fusion degradation (UFD) pathway. In wild-type cells, Ub-P-βgal is modified with ubiquitin chains consisting of 21% K29- and 78% K48-linked chains. In contrast, K29-linked chains are not detected in UFD4 knockout cells, suggesting that Ufd4 assembles the K29-linked ubiquitin chain(s) on Ub-P-βgal in vivo. Thus, the ubiquitin PRM is a novel, useful, quantitative method for analyzing the highly complicated ubiquitin system.« less

Effects of Cloud Particles on Remote Sensing from Space in the 10-Micrometer Infrared Region.

DTIC Science & Technology

1977-01-01

ayers , that is , a plane-parallel atmosphere wi th infinite hori zontal extent . As a matter of fact, this is how the planeta ry atmosphere is being...Remote Probin g of the Atmosphe re, 1973. 43 . Hansen , J. E. and L. D. Travis , 1974 , “Light Scattering in Planeta ry • Atmospheres ,” Goddard

Micromechanics-based magneto-elastic constitutive modeling of particulate composites

NASA Astrophysics Data System (ADS)

Yin, Huiming

Modified Green's functions are derived for three situations: a magnetic field caused by a local magnetization, a displacement field caused by a local body force and a displacement field caused by a local prescribed eigenstrain. Based on these functions, an explicit solution is derived for two magnetic particles embedded in the infinite medium under external magnetic and mechanical loading. A general solution for numerable magnetic particles embedded in an infinite domain is then provided in integral form. Two-phase composites containing spherical magnetic particles of the same size are considered for three kinds of microstructures. With chain-structured composites, particle interactions in the same chain are considered and a transversely isotropic effective elasticity is obtained. For periodic composites, an eight-particle interaction model is developed and provides a cubic symmetric effective elasticity. In the random composite, pair-wise particle interactions are integrated from all possible positions and an isotropic effective property is reached. This method is further extended to functionally graded composites. Magneto-mechanical behavior is studied for the chain-structured composite and the random composite. Effective magnetic permeability, effective magnetostriction and field-dependent effective elasticity are investigated. It is seen that the chain-structured composite is more sensitive to the magnetic field than the random composite; a composite consisting of only 5% of chain-structured particles can provide a larger magnetostriction and a larger change of effective elasticity than an equivalent composite consisting of 30% of random dispersed particles. Moreover, the effective shear modulus of the chain-structured composite rapidly increases with the magnetic field, while that for the random composite decreases. An effective hyperelastic constitutive model is further developed for a magnetostrictive particle-filled elastomer, which is sampled by using a network of body-centered cubic lattices of particles connected by macromolecular chains. The proposed hyperelastic model is able to characterize overall nonlinear elastic stress-stretch relations of the composites under general three-dimensional loading. It is seen that the effective strain energy density is proportional to the length of stretched chains in unit volume and volume fraction of particles.

Complete devil's staircase and crystal-superfluid transitions in a dipolar XXZ spin chain: a trapped ion quantum simulation

NASA Astrophysics Data System (ADS)

Hauke, Philipp; Cucchietti, Fernando M.; Müller-Hermes, Alexander; Bañuls, Mari-Carmen; Cirac, J. Ignacio; Lewenstein, Maciej

2010-11-01

Systems with long-range interactions show a variety of intriguing properties: they typically accommodate many metastable states, they can give rise to spontaneous formation of supersolids, and they can lead to counterintuitive thermodynamic behavior. However, the increased complexity that comes with long-range interactions strongly hinders theoretical studies. This makes a quantum simulator for long-range models highly desirable. Here, we show that a chain of trapped ions can be used to quantum simulate a one-dimensional (1D) model of hard-core bosons with dipolar off-site interaction and tunneling, equivalent to a dipolar XXZ spin-1/2 chain. We explore the rich phase diagram of this model in detail, employing perturbative mean-field theory, exact diagonalization and quasi-exact numerical techniques (density-matrix renormalization group and infinite time-evolving block decimation). We find that the complete devil's staircase—an infinite sequence of crystal states existing at vanishing tunneling—spreads to a succession of lobes similar to the Mott lobes found in Bose-Hubbard models. Investigating the melting of these crystal states at increased tunneling, we do not find (contrary to similar 2D models) clear indications of supersolid behavior in the region around the melting transition. However, we find that inside the insulating lobes there are quasi-long-range (algebraic) correlations, as opposed to models with nearest-neighbor tunneling, that show exponential decay of correlations.

Teaching Wave Propagation and the Emergence of Viete's Formula

ERIC Educational Resources Information Center

Cullerne, J. P.; Goekjian, M. C. Dunn

2012-01-01

The well-known result for the frequency of a simple spring-mass system may be combined with elementary concepts like speed = wavelength x frequency to obtain wave propagation speeds for an infinite chain of springs and masses (masses "m" held apart at equilibrium distance "a" by springs of stiffness "gamma"). These propagation speeds are dependent…

1-Benzyl-2-(1H-indol-3-yl)-5-oxo-pyrrolidine-2-carbonitrile.

PubMed

Tamazyan, Rafael; Armen, Ayvazyan; Ashot, Martirosyan; Sahak, Gasparyan; Schinazi, Raymond

2008-01-04

In the title compound, C(20)H(17)N(3)O, a potential anti-human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse-transcriptase inhibitor, the pyrrolidine ring has an envelope conformation. In the crystal structure, adjacent mol-ecules are connected into infinite chains via an N-H⋯O hydrogen bond.

Distributed parameter system coupled ARMA expansion identification and adaptive parallel IIR filtering - A unified problem statement. [Auto Regressive Moving-Average

NASA Technical Reports Server (NTRS)

Johnson, C. R., Jr.; Balas, M. J.

1980-01-01

A novel interconnection of distributed parameter system (DPS) identification and adaptive filtering is presented, which culminates in a common statement of coupled autoregressive, moving-average expansion or parallel infinite impulse response configuration adaptive parameterization. The common restricted complexity filter objectives are seen as similar to the reduced-order requirements of the DPS expansion description. The interconnection presents the possibility of an exchange of problem formulations and solution approaches not yet easily addressed in the common finite dimensional lumped-parameter system context. It is concluded that the shared problems raised are nevertheless many and difficult.

Analytical theory of coherent synchrotron radiation wakefield of short bunches shielded by conducting parallel plates

NASA Astrophysics Data System (ADS)

Stupakov, Gennady; Zhou, Demin

2016-04-01

We develop a general model of coherent synchrotron radiation (CSR) impedance with shielding provided by two parallel conducting plates. This model allows us to easily reproduce all previously known analytical CSR wakes and to expand the analysis to situations not explored before. It reduces calculations of the impedance to taking integrals along the trajectory of the beam. New analytical results are derived for the radiation impedance with shielding for the following orbits: a kink, a bending magnet, a wiggler of finite length, and an infinitely long wiggler. All our formulas are benchmarked against numerical simulations with the CSRZ computer code.

Analytical theory of coherent synchrotron radiation wakefield of short bunches shielded by conducting parallel plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stupakov, Gennady; Zhou, Demin

2016-04-21

We develop a general model of coherent synchrotron radiation (CSR) impedance with shielding provided by two parallel conducting plates. This model allows us to easily reproduce all previously known analytical CSR wakes and to expand the analysis to situations not explored before. It reduces calculations of the impedance to taking integrals along the trajectory of the beam. New analytical results are derived for the radiation impedance with shielding for the following orbits: a kink, a bending magnet, a wiggler of finite length, and an infinitely long wiggler. All our formulas are benchmarked against numerical simulations with the CSRZ computer code.

Diverging conductance at the contact between random and pure quantum XX spin chains

NASA Astrophysics Data System (ADS)

Chatelain, Christophe

2017-11-01

A model consisting of two quantum XX spin chains, one homogeneous and the second with random couplings drawn from a binary distribution, is considered. The two chains are coupled to two different non-local thermal baths and their dynamics is governed by a Lindblad equation. In the steady state, a current J is induced between the two chains by coupling them together by their edges and imposing different chemical potentials μ to the two baths. While a regime of linear characteristics J versus Δμ is observed in the absence of randomness, a gap opens as the disorder strength is increased. In the infinite-randomness limit, this behavior is related to the density of states of the localized states contributing to the current. The conductance is shown to diverge in this limit.

A COMPARISON OF TRANSIENT INFINITE ELEMENTS AND TRANSIENT KIRCHHOFF INTEGRAL METHODS FOR FAR FIELD ACOUSTIC ANALYSIS

DOE PAGES

WALSH, TIMOTHY F.; JONES, ANDREA; BHARDWAJ, MANOJ; ...

2013-04-01

Finite element analysis of transient acoustic phenomena on unbounded exterior domains is very common in engineering analysis. In these problems there is a common need to compute the acoustic pressure at points outside of the acoustic mesh, since meshing to points of interest is impractical in many scenarios. In aeroacoustic calculations, for example, the acoustic pressure may be required at tens or hundreds of meters from the structure. In these cases, a method is needed for post-processing the acoustic results to compute the response at far-field points. In this paper, we compare two methods for computing far-field acoustic pressures, onemore » derived directly from the infinite element solution, and the other from the transient version of the Kirchhoff integral. Here, we show that the infinite element approach alleviates the large storage requirements that are typical of Kirchhoff integral and related procedures, and also does not suffer from loss of accuracy that is an inherent part of computing numerical derivatives in the Kirchhoff integral. In order to further speed up and streamline the process of computing the acoustic response at points outside of the mesh, we also address the nonlinear iterative procedure needed for locating parametric coordinates within the host infinite element of far-field points, the parallelization of the overall process, linear solver requirements, and system stability considerations.« less

Translational Dielectric Friction on a Chain of Charged Spheres

PubMed Central

Boughammoura, Sondès; M'halla, Jalel

2014-01-01

We have proved in details that the dielectric friction remains the principal frictional effect for a stretched polyion modeled as a chain of charged spheres, whereas, in the case of Manning's model (infinite thread with a continuous distribution of charge), this friction effect is nonexistent. According to this chain model, it is therefore possible to detect by conductivity measurements any transition from a coiled configuration (ellipsoidal model) to a stretched configuration during dilution process. We have also underlined the important interdependence between the dielectric friction and the ionic condensation of the counterions, in order to distinguish between the Ostwald regime and the Manning regime for which the degree of condensation is practically constant in a large range of concentrations. PMID:24672333

Determination of backbone chain direction of PDA using FFM

NASA Astrophysics Data System (ADS)

Jo, Sadaharu; Okamoto, Kentaro; Takenaga, Mitsuru

2010-01-01

The effect of backbone chains on friction force was investigated on both Langmuir-Blodgett (LB) films of 10,12-heptacosadiynoic acid and the (0 1 0) surfaces of single crystals of 2,4-hexadiene-1,6-diol using friction force microscopy (FFM). It was observed that friction force decreased when the scanning direction was parallel to the [0 0 1] direction in both samples. Moreover, friction force decreased when the scanning direction was parallel to the crystallographic [1 0 2], [1 0 1], [1 0 0] and [1 0 1¯] directions in only the single crystals. For the LB films, the [0 0 1] direction corresponds to the backbone chain direction of 10,12-heptacosadiynoic acid. For the single crystals, both the [0 0 1] and [1 0 1] directions correspond to the backbone chain direction, and the [1 0 2], [1 0 0] and [1 0 1¯] directions correspond to the low-index crystallographic direction. In both the LB films and single crystals, the friction force was minimized when the directions of scanning and the backbone chain were parallel.

Probability distributions for Markov chain based quantum walks

NASA Astrophysics Data System (ADS)

Balu, Radhakrishnan; Liu, Chaobin; Venegas-Andraca, Salvador E.

2018-01-01

We analyze the probability distributions of the quantum walks induced from Markov chains by Szegedy (2004). The first part of this paper is devoted to the quantum walks induced from finite state Markov chains. It is shown that the probability distribution on the states of the underlying Markov chain is always convergent in the Cesaro sense. In particular, we deduce that the limiting distribution is uniform if the transition matrix is symmetric. In the case of a non-symmetric Markov chain, we exemplify that the limiting distribution of the quantum walk is not necessarily identical with the stationary distribution of the underlying irreducible Markov chain. The Szegedy scheme can be extended to infinite state Markov chains (random walks). In the second part, we formulate the quantum walk induced from a lazy random walk on the line. We then obtain the weak limit of the quantum walk. It is noted that the current quantum walk appears to spread faster than its counterpart-quantum walk on the line driven by the Grover coin discussed in literature. The paper closes with an outlook on possible future directions.

1-Benzyl-2-(1H-indol-3-yl)-5-oxo­pyrrolidine-2-carbonitrile

PubMed Central

Tamazyan, Rafael; Armen, Ayvazyan; Ashot, Martirosyan; Sahak, Gasparyan; Schinazi, Raymond

2008-01-01

In the title compound, C20H17N3O, a potential anti-human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse-transcriptase inhibitor, the pyrrolidine ring has an envelope conformation. In the crystal structure, adjacent mol­ecules are connected into infinite chains via an N—H⋯O hydrogen bond. PMID:21201400

Crystal structure of di­methyl­ammonium hydrogen oxalate hemi(oxalic acid)

PubMed Central

Diallo, Waly; Gueye, Ndongo; Crochet, Aurélien; Plasseraud, Laurent; Cattey, Hélène

2015-01-01

Single crystals of the title salt, Me2NH2 +·HC2O4 −·0.5H2C2O4, were isolated as a side product from the reaction involving Me2NH, H2C2O4 and Sn(n-Bu)3Cl in a 1:2 ratio in methanol or by the reaction of the (Me2NH2)2C2O4 salt and Sn(CH3)3Cl in a 2:1 ratio in ethanol. The asymmetric unit comprises a di­methyl­ammonium cation (Me2NH2 +), an hydrogenoxalate anion (HC2O4 −), and half a mol­ecule of oxalic acid (H2C2O4) situated about an inversion center. From a supra­molecular point of view, the three components inter­act together via hydrogen bonding. The Me2NH2 + cations and the HC2O4 − anions are in close proximity through bifurcated N—H⋯(O,O) hydrogen bonds, while the HC2O4 − anions are organized into infinite chains via O—H⋯O hydrogen bonds, propagating along the a-axis direction. In addition, the oxalic acid (H2C2O4) mol­ecules play the role of connectors between these chains. Both the carbonyl and hydroxyl groups of each diacid are involved in four inter­molecular inter­actions with two Me2NH2 + and two HC2O4 − ions of four distinct polymeric chains, via two N—H⋯O and two O—H⋯O hydrogen bonds, respectively. The resulting mol­ecular assembly can be viewed as a two-dimensional bilayer-like arrangement lying parallel to (010), and reinforced by a C—H⋯O hydrogen bond. PMID:25995858

An organic jelly made fractal logic gate with an infinite truth table

PubMed Central

Ghosh, Subrata; Fujita, Daisuke; Bandyopadhyay, Anirban

2015-01-01

Widely varying logic gates invented over a century are all finite. As data deluge problem looms large on the information processing and communication industry, the thrust to explore radical concepts is increasing rapidly. Here, we design and synthesis a molecule, wherein, the input energy transmits in a cycle inside the molecular system, just like an oscillator, then, we use the molecule to make a jelly that acts as chain of oscillators with a fractal like resonance band. Hence, with the increasing detection resolution, in the vacant space between two energy levels of a given resonance band, a new band appears, due to fractal nature, generation of newer energy levels never stops. This is natural property of a linear chain oscillator. As we correlate each energy level of the resonance band of organic jelly, as a function of pH and density of the jelly, we realize a logic gate, whose truth table is finite, but if we zoom any small part, a new truth table appears. In principle, zooming of truth table would continue forever. Thus, we invent a new class of infinite logic gate for the first time. PMID:26086417

Structure and magnetism of a new hydrogen-bonded layered cobalt(II) network, constructed by the unprecedented carboxylate-phosphinate ligand [O2(C6H5)PCH2CO2]2-.

PubMed

Midollini, Stefano; Orlandini, Annabella; Rosa, Patrick; Sorace, Lorenzo

2005-03-21

By hydrothermal reaction of CoCl2 x 6H2O with K2pcc (H2pcc = phenyl(carboxymethyl) phosphinic acid) at 423 K, a novel hybrid material of formula [Co2(pcc)2 (H2O)2] x H2O has been obtained. The compound, which is the first pcc/metal complex reported, exhibits a polymeric arrangement, where cobalt metal ions, linked together by bridging carboxylate and phosphinate oxygens, form infinite chains of edge-shared CoO6 octahedra. The cobalt chains are in turn linked together through important hydrogen-bonding interactions, which create an infinite 2D architecture. The two crystallographically independent cobalt centers, both displaying distorted octahedral coordination, present different environments as one is surrounded by six ligand oxygens and the other by four ligand oxygens and by two water oxygens. Careful magnetic studies performed by a home-built alternating current susceptometer reveal that the system undergoes an antiferromagnetic transition below 2.0 K leading to a canted structure. Field-dependent studies further indicate the occurrence of a metamagnetic transition at a critical field of 650 +/- 50 G.

Architectures for reasoning in parallel

NASA Technical Reports Server (NTRS)

Hall, Lawrence O.

1989-01-01

The research conducted has dealt with rule-based expert systems. The algorithms that may lead to effective parallelization of them were investigated. Both the forward and backward chained control paradigms were investigated in the course of this work. The best computer architecture for the developed and investigated algorithms has been researched. Two experimental vehicles were developed to facilitate this research. They are Backpac, a parallel backward chained rule-based reasoning system and Datapac, a parallel forward chained rule-based reasoning system. Both systems have been written in Multilisp, a version of Lisp which contains the parallel construct, future. Applying the future function to a function causes the function to become a task parallel to the spawning task. Additionally, Backpac and Datapac have been run on several disparate parallel processors. The machines are an Encore Multimax with 10 processors, the Concert Multiprocessor with 64 processors, and a 32 processor BBN GP1000. Both the Concert and the GP1000 are switch-based machines. The Multimax has all its processors hung off a common bus. All are shared memory machines, but have different schemes for sharing the memory and different locales for the shared memory. The main results of the investigations come from experiments on the 10 processor Encore and the Concert with partitions of 32 or less processors. Additionally, experiments have been run with a stripped down version of EMYCIN.

Resonant scattering from a two-dimensional honeycomb PT dipole structure

NASA Astrophysics Data System (ADS)

Markoš, P.; Kuzmiak, V.

2018-05-01

We studied numerically the electromagnetic response of the finite periodic structure consisting of the PT dipoles represented by two infinitely long, parallel cylinders with the opposite sign of the imaginary part of a refractive index, which are centered at the positions of a two-dimensional honeycomb lattice. We observed that the total scattered energy reveals a series of sharp resonances at which the energy increases by two orders of magnitude and an incident wave is scattered only in a few directions given by spatial symmetry of the periodic structure. We explain this behavior by analysis of the complex frequency spectra associated with an infinite honeycomb array of the PT dipoles and identify the lowest resonance with the broken PT -symmetry mode formed by a doubly degenerate pair with complex conjugate eigenfrequencies corresponding to the K point of the reciprocal lattice.

Linear and nonlinear susceptibilities from diffusion quantum Monte Carlo: application to periodic hydrogen chains.

PubMed

Umari, P; Marzari, Nicola

2009-09-07

We calculate the linear and nonlinear susceptibilities of periodic longitudinal chains of hydrogen dimers with different bond-length alternations using a diffusion quantum Monte Carlo approach. These quantities are derived from the changes in electronic polarization as a function of applied finite electric field--an approach we recently introduced and made possible by the use of a Berry-phase, many-body electric-enthalpy functional. Calculated susceptibilities and hypersusceptibilities are found to be in excellent agreement with the best estimates available from quantum chemistry--usually extrapolations to the infinite-chain limit of calculations for chains of finite length. It is found that while exchange effects dominate the proper description of the susceptibilities, second hypersusceptibilities are greatly affected by electronic correlations. We also assess how different approximations to the nodal surface of the many-body wave function affect the accuracy of the calculated susceptibilities.

Almost-dispersionless pulse transport in long quasiuniform spring-mass chains: A different kind of Newton's cradle

NASA Astrophysics Data System (ADS)

Vaia, Ruggero

2018-04-01

Almost-dispersionless pulse transfer between the extremal masses of a uniform harmonic spring-mass chain of arbitrary length can be induced by suitably modifying two masses and their spring's elastic constant at both extrema of the chain. It is shown that a deviation (or a pulse) imposed to the first mass gives rise to a wave packet that, after a time of the order of the chain length, almost perfectly reproduces the same deviation (pulse) at the opposite end, with an amplitude loss that is as small as 1.3% in the infinite-length limit; such a dynamics can continue back and forth again for several times before dispersion cleared the effect. The underlying coherence mechanism is that the initial condition excites a bunch of normal modes with almost equal frequency spacing. This constitutes a possible mechanism for efficient energy transfer, e.g., in nanofabricated structures.

Laboratory Graduate Fellowship Program, 1989. Appendix E

DTIC Science & Technology

1989-01-01

odd number of (100) sublattice planes across the film. 3Nonreciprocal properties also have a number of important technological applications. 8 ,9 A...as connecting a receiver and transmitter to the same antenna) by using the I property that ferromagnetic magnetostatic waves on thick films only...geometry used throughout this dissertation is I semi-infinite with the surface plane parallel to the easy axis. The net magnetization normal to the easy

Reactive silica transport in fractured porous media: Analytical solutions for a system of parallel fractures

NASA Astrophysics Data System (ADS)

Yang, Jianwen

2012-04-01

A general analytical solution is derived by using the Laplace transformation to describe transient reactive silica transport in a conceptualized 2-D system involving a set of parallel fractures embedded in an impermeable host rock matrix, taking into account of hydrodynamic dispersion and advection of silica transport along the fractures, molecular diffusion from each fracture to the intervening rock matrix, and dissolution of quartz. A special analytical solution is also developed by ignoring the longitudinal hydrodynamic dispersion term but remaining other conditions the same. The general and special solutions are in the form of a double infinite integral and a single infinite integral, respectively, and can be evaluated using Gauss-Legendre quadrature technique. A simple criterion is developed to determine under what conditions the general analytical solution can be approximated by the special analytical solution. It is proved analytically that the general solution always lags behind the special solution, unless a dimensionless parameter is less than a critical value. Several illustrative calculations are undertaken to demonstrate the effect of fracture spacing, fracture aperture and fluid flow rate on silica transport. The analytical solutions developed here can serve as a benchmark to validate numerical models that simulate reactive mass transport in fractured porous media.

Albedo of an irradiated plane-parallel atmosphere with finite optical depth

NASA Astrophysics Data System (ADS)

Fukue, Jun

2018-03-01

We analytically derive albedo for a plane-parallel atmosphere with finite optical depth, irradiated by an external source, under the local thermodynamic equilibrium approximation. Albedo is expressed as a function of the photon destruction probability ɛ and optical depth τ, with several parameters such as dilution factors of the external source. In the particular case of the infinite optical depth, albedo A is expressed as A=[1 + (1-W_J/W_H)√{3ɛ}/3]/(1+√{3ɛ}), where WJ and WH are the dilution factors for the mean intensity and Eddington flux, respectively. An example of a model atmosphere is also presented under a gray approximation.

Analytical theory of coherent synchrotron radiation wakefield of short bunches shielded by conducting parallel plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stupakov, Gennady; Zhou, Demin

2016-04-21

We develop a general model of coherent synchrotron radiation (CSR) impedance with shielding provided by two parallel conducting plates. This model allows us to easily reproduce all previously known analytical CSR wakes and to expand the analysis to situations not explored before. It reduces calculations of the impedance to taking integrals along the trajectory of the beam. New analytical results are derived for the radiation impedance with shielding for the following orbits: a kink, a bending magnet, a wiggler of finite length, and an infinitely long wiggler. Furthermore, all our formulas are benchmarked against numerical simulations with the CSRZ computermore » code.« less

Localized Single Frequency Lasing States in a Finite Parity-Time Symmetric Resonator Chain

PubMed Central

Phang, Sendy; Vukovic, Ana; Creagh, Stephen C.; Sewell, Phillip D.; Gradoni, Gabriele; Benson, Trevor M.

2016-01-01

In this paper a practical case of a finite periodic Parity Time chain made of resonant dielectric cylinders is considered. The paper analyzes a more general case where PT symmetry is achieved by modulating both the real and imaginary part of the material refractive index along the resonator chain. The band-structure of the finite periodic PT resonator chains is compared to infinite chains in order to understand the complex interdependence of the Bloch phase and the amount of the gain/loss in the system that causes the PT symmetry to break. The results show that the type of the modulation along the unit cell can significantly affect the position of the threshold point of the PT system. In all cases the lowest threshold is achieved near the end of the Brillouin zone. In the case of finite PT-chains, and for a particular type of modulation, early PT symmetry breaking is observed and shown to be caused by the presence of termination states localized at the edges of the finite chain resulting in localized lasing and dissipative modes at each end of the chain. PMID:26848095

Electronic band gaps of confined linear carbon chains ranging from polyyne to carbyne

NASA Astrophysics Data System (ADS)

Shi, Lei; Rohringer, Philip; Wanko, Marius; Rubio, Angel; Waßerroth, Sören; Reich, Stephanie; Cambré, Sofie; Wenseleers, Wim; Ayala, Paola; Pichler, Thomas

2017-12-01

Ultralong linear carbon chains of more than 6000 carbon atoms have recently been synthesized within double-walled carbon nanotubes (DWCNTs), and they show a promising route to one-atom-wide semiconductors with a direct band gap. Theoretical studies predicted that this band gap can be tuned by the length of the chains, the end groups, and their interactions with the environment. However, different density functionals lead to very different values of the band gap of infinitely long carbyne. In this work, we applied resonant Raman excitation spectroscopy with more than 50 laser wavelengths to determine the band gap of long carbon chains encapsulated inside DWCNTs. The experimentally determined band gaps ranging from 2.253 to 1.848 eV follow a linear relation with Raman frequency. This lower bound is the smallest band gap of linear carbon chains observed so far. The comparison with experimental data obtained for short chains in gas phase or in solution demonstrates the effect of the DWCNT encapsulation, leading to an essential downshift of the band gap. This is explained by the interaction between the carbon chain and the host tube, which greatly modifies the chain's bond-length alternation.

Quantum communication beyond the localization length in disordered spin chains.

PubMed

Allcock, Jonathan; Linden, Noah

2009-03-20

We study the effects of localization on quantum state transfer in spin chains. We show how to use quantum error correction and multiple parallel spin chains to send a qubit with high fidelity over arbitrary distances, in particular, distances much greater than the localization length of the chain.

Low frequency full waveform seismic inversion within a tree based Bayesian framework

NASA Astrophysics Data System (ADS)

Ray, Anandaroop; Kaplan, Sam; Washbourne, John; Albertin, Uwe

2018-01-01

Limited illumination, insufficient offset, noisy data and poor starting models can pose challenges for seismic full waveform inversion. We present an application of a tree based Bayesian inversion scheme which attempts to mitigate these problems by accounting for data uncertainty while using a mildly informative prior about subsurface structure. We sample the resulting posterior model distribution of compressional velocity using a trans-dimensional (trans-D) or Reversible Jump Markov chain Monte Carlo method in the wavelet transform domain of velocity. This allows us to attain rapid convergence to a stationary distribution of posterior models while requiring a limited number of wavelet coefficients to define a sampled model. Two synthetic, low frequency, noisy data examples are provided. The first example is a simple reflection + transmission inverse problem, and the second uses a scaled version of the Marmousi velocity model, dominated by reflections. Both examples are initially started from a semi-infinite half-space with incorrect background velocity. We find that the trans-D tree based approach together with parallel tempering for navigating rugged likelihood (i.e. misfit) topography provides a promising, easily generalized method for solving large-scale geophysical inverse problems which are difficult to optimize, but where the true model contains a hierarchy of features at multiple scales.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hao; Malliakas, Christos D.; Han, Fei

The quaternary compound TlHgInS3 crystallizes in a new structure type of space group, C2/c, with cell parameters a = 13.916(3) angstrom, b = 3.9132(8) angstrom, c = 21.403(4) angstrom, beta = 104.16(3)degrees, V = 1130.1(8) angstrom(3), and rho = 7.241 g/cm(3). The structure is a unique three-dimensional framework with parallel tunnels, which is formed by (1)(infinity)[InS33-] infinite chains bridged by linearly coordinated Hg2+ ions. TlHgInS3 is a semiconductor with a band gap of 1.74 eV and a resistivity of similar to 4.32 G Omega cm. TlHgInS3 single crystals exhibit photocurrent response when exposed to Ag X-rays. The mobility-lifetime product (mumore » tau) of the electrons and holes estimated from the photocurrent measurements are (mu tau)(e) approximate to 3.6 x 10(-4) cm(2)/V and (mu tau)(h) approximate to 2.0 x 10(-4) cm(2)/V. Electronic structure calculations at the density functional theory level indicate an indirect band gap and a relatively small effective mass for both electrons and holes. Based on the photoconductivity data, TlHgInS3 is a potential material for radiation detection applications.« less

Analysis of Streamline Separation at Infinity Using Time-Discrete Markov Chains.

PubMed

Reich, W; Scheuermann, G

2012-12-01

Existing methods for analyzing separation of streamlines are often restricted to a finite time or a local area. In our paper we introduce a new method that complements them by allowing an infinite-time-evaluation of steady planar vector fields. Our algorithm unifies combinatorial and probabilistic methods and introduces the concept of separation in time-discrete Markov-Chains. We compute particle distributions instead of the streamlines of single particles. We encode the flow into a map and then into a transition matrix for each time direction. Finally, we compare the results of our grid-independent algorithm to the popular Finite-Time-Lyapunov-Exponents and discuss the discrepancies.

Crystal structure of methyl (4R)-4-(4-meth-oxy-benzo-yl)-4-{[(1R)-1-phenyl-eth-yl]carbamo-yl}butano-ate.

PubMed

Manchado, Alejandro; Salgado, Mateo M; Vicente, Álvaro; Díez, David; Sanz, Francisca; Garrido, Narciso M

2017-04-01

The title compound, C 22 H 25 NO 5 , was prepared by CAN [cerium(IV) ammonium nitrate] oxidation of the corresponding β-lactam. The dihedral angle between the benzene rings is 13.3 (4)° and the C-N-C(=O)-C torsion angle is 176.1 (6)°. In the crystal, amide- C (4) N-H⋯O and reinforcing C-H⋯O hydrogen bonds link the mol-ecules into infinite [010] chains. Further C-H⋯O hydrogen bonds cross-link the chains in the c -axis direction.

Functions Character

NASA Astrophysics Data System (ADS)

Dugave, Maxime; Göhmann, Frank; Kozlowski, Karol Kajetan

2014-04-01

We establish several properties of the solutions to the linear integral equations describing the infinite volume properties of the XXZ spin-1/2 chain in the disordered regime. In particular, we obtain lower and upper bounds for the dressed energy, dressed charge and density of Bethe roots. Furthermore, we establish that given a fixed external magnetic field (or a fixed magnetization) there exists a unique value of the boundary of the Fermi zone.

Topology of polymer chains under nanoscale confinement.

PubMed

Satarifard, Vahid; Heidari, Maziar; Mashaghi, Samaneh; Tans, Sander J; Ejtehadi, Mohammad Reza; Mashaghi, Alireza

2017-08-24

Spatial confinement limits the conformational space accessible to biomolecules but the implications for bimolecular topology are not yet known. Folded linear biopolymers can be seen as molecular circuits formed by intramolecular contacts. The pairwise arrangement of intra-chain contacts can be categorized as parallel, series or cross, and has been identified as a topological property. Using molecular dynamics simulations, we determine the contact order distributions and topological circuits of short semi-flexible linear and ring polymer chains with a persistence length of l p under a spherical confinement of radius R c . At low values of l p /R c , the entropy of the linear chain leads to the formation of independent contacts along the chain and accordingly, increases the fraction of series topology with respect to other topologies. However, at high l p /R c , the fraction of cross and parallel topologies are enhanced in the chain topological circuits with cross becoming predominant. At an intermediate confining regime, we identify a critical value of l p /R c , at which all topological states have equal probability. Confinement thus equalizes the probability of more complex cross and parallel topologies to the level of the more simple, non-cooperative series topology. Moreover, our topology analysis reveals distinct behaviours for ring- and linear polymers under weak confinement; however, we find no difference between ring- and linear polymers under strong confinement. Under weak confinement, ring polymers adopt parallel and series topologies with equal likelihood, while linear polymers show a higher tendency for series arrangement. The radial distribution analysis of the topology reveals a non-uniform effect of confinement on the topology of polymer chains, thereby imposing more pronounced effects on the core region than on the confinement surface. Additionally, our results reveal that over a wide range of confining radii, loops arranged in parallel and cross topologies have nearly the same contact orders. Such degeneracy implies that the kinetics and transition rates between the topological states cannot be solely explained by contact order. We expect these findings to be of general importance in understanding chaperone assisted protein folding, chromosome architecture, and the evolution of molecular folds.

Ultrastrong coupling in supersymmetric gauge theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buchel, Alex

1999-10-04

We study 'ultrastrong' coupling points in scale-invariant N=2 gauge theories. These are theories where, naively, the coupling becomes infinite, and is not related by S-duality to a weak coupling point. These theories have been somewhat of a mystery, since in the M-theory description they correspond to points where parallel M 5-branes coincide. Using the low-energy effective field theory arguments we relate these theories to other known N=2 CFT.

Anomalous critical slowdown at a first order phase transition in single polymer chains.

PubMed

Zhang, Shuangshuang; Qi, Shuanhu; Klushin, Leonid I; Skvortsov, Alexander M; Yan, Dadong; Schmid, Friederike

2017-08-14

Using Brownian dynamics, we study the dynamical behavior of a polymer grafted onto an adhesive surface close to the mechanically induced adsorption-stretching transition. Even though the transition is first order (in the infinite chain length limit, the stretching degree of the chain jumps discontinuously), the characteristic relaxation time is found to grow according to a power law as the transition point is approached. We present a dynamic effective interface model which reproduces these observations and provides an excellent quantitative description of the simulation data. The generic nature of the theoretical model suggests that the unconventional mixing of features that are characteristic for first-order transitions (a jump in an order parameter) and features that are characteristic of critical points (an anomalous slowdown) may be a common phenomenon in force-driven phase transitions of macromolecules.

Quasineutral plasma expansion into infinite vacuum as a model for parallel ELM transport

NASA Astrophysics Data System (ADS)

Moulton, D.; Ghendrih, Ph; Fundamenski, W.; Manfredi, G.; Tskhakaya, D.

2013-08-01

An analytic solution for the expansion of a plasma into vacuum is assessed for its relevance to the parallel transport of edge localized mode (ELM) filaments along field lines. This solution solves the 1D1V Vlasov-Poisson equations for the adiabatic (instantaneous source), collisionless expansion of a Gaussian plasma bunch into an infinite space in the quasineutral limit. The quasineutral assumption is found to hold as long as λD0/σ0 ≲ 0.01 (where λD0 is the initial Debye length at peak density and σ0 is the parallel length of the Gaussian filament), a condition that is physically realistic. The inclusion of a boundary at x = L and consequent formation of a target sheath is found to have a negligible effect when L/σ0 ≳ 5, a condition that is physically plausible. Under the same condition, the target flux densities predicted by the analytic solution are well approximated by the ‘free-streaming’ equations used in previous experimental studies, strengthening the notion that these simple equations are physically reasonable. Importantly, the analytic solution predicts a zero heat flux density so that a fluid approach to the problem can be used equally well, at least when the source is instantaneous. It is found that, even for JET-like pedestal parameters, collisions can affect the expansion dynamics via electron temperature isotropization, although this is probably a secondary effect. Finally, the effect of a finite duration, τsrc, for the plasma source is investigated. As is found for an instantaneous source, when L/σ0 ≳ 5 the presence of a target sheath has a negligible effect, at least up to the explored range of τsrc = L/cs (where cs is the sound speed at the initial temperature).

Elastic relaxation of a truncated circular cylinder with uniform dilatational eigenstrain in a half space

NASA Astrophysics Data System (ADS)

Glas, Frank

2003-06-01

We give a fully analytical solution for the displacement and strain fields generated by the coherent elastic relaxation of a type of misfitting inclusions with uniform dilatational eigenstrain lying in a half space, assuming linear isotropic elasticity. The inclusion considered is an infinitely long circular cylinder having an axis parallel to the free surface and truncated by two arbitrarily positioned planes parallel to this surface. These calculations apply in particular to strained semiconductor quantum wires. The calculations are illustrated by examples showing quantitatively that, depending on the depth of the wire under the free surface, the latter may significantly affect the magnitude and the distribution of the various strain components inside the inclusion as well as in the surrounding matrix.

Verification and Planning Based on Coinductive Logic Programming

NASA Technical Reports Server (NTRS)

Bansal, Ajay; Min, Richard; Simon, Luke; Mallya, Ajay; Gupta, Gopal

2008-01-01

Coinduction is a powerful technique for reasoning about unfounded sets, unbounded structures, infinite automata, and interactive computations [6]. Where induction corresponds to least fixed point's semantics, coinduction corresponds to greatest fixed point semantics. Recently coinduction has been incorporated into logic programming and an elegant operational semantics developed for it [11, 12]. This operational semantics is the greatest fix point counterpart of SLD resolution (SLD resolution imparts operational semantics to least fix point based computations) and is termed co- SLD resolution. In co-SLD resolution, a predicate goal p( t) succeeds if it unifies with one of its ancestor calls. In addition, rational infinite terms are allowed as arguments of predicates. Infinite terms are represented as solutions to unification equations and the occurs check is omitted during the unification process. Coinductive Logic Programming (Co-LP) and Co-SLD resolution can be used to elegantly perform model checking and planning. A combined SLD and Co-SLD resolution based LP system forms the common basis for planning, scheduling, verification, model checking, and constraint solving [9, 4]. This is achieved by amalgamating SLD resolution, co-SLD resolution, and constraint logic programming [13] in a single logic programming system. Given that parallelism in logic programs can be implicitly exploited [8], complex, compute-intensive applications (planning, scheduling, model checking, etc.) can be executed in parallel on multi-core machines. Parallel execution can result in speed-ups as well as in larger instances of the problems being solved. In the remainder we elaborate on (i) how planning can be elegantly and efficiently performed under real-time constraints, (ii) how real-time systems can be elegantly and efficiently model- checked, as well as (iii) how hybrid systems can be verified in a combined system with both co-SLD and SLD resolution. Implementations of co-SLD resolution as well as preliminary implementations of the planning and verification applications have been developed [4]. Co-LP and Model Checking: The vast majority of properties that are to be verified can be classified into safety properties and liveness properties. It is well known within model checking that safety properties can be verified by reachability analysis, i.e, if a counter-example to the property exists, it can be finitely determined by enumerating all the reachable states of the Kripke structure.

Transport in simple networks described by an integrable discrete nonlinear Schrödinger equation.

PubMed

Nakamura, K; Sobirov, Z A; Matrasulov, D U; Sawada, S

2011-08-01

We elucidate the case in which the Ablowitz-Ladik (AL)-type discrete nonlinear Schrödinger equation (NLSE) on simple networks (e.g., star graphs and tree graphs) becomes completely integrable just as in the case of a simple one-dimensional (1D) discrete chain. The strength of cubic nonlinearity is different from bond to bond, and networks are assumed to have at least two semi-infinite bonds with one of them working as an incoming bond. The present work is a nontrivial extension of our preceding one [Sobirov et al., Phys. Rev. E 81, 066602 (2010)] on the continuum NLSE to the discrete case. We find (1) the solution on each bond is a part of the universal (bond-independent) AL soliton solution on the 1D discrete chain, but it is multiplied by the inverse of the square root of bond-dependent nonlinearity; (2) nonlinearities at individual bonds around each vertex must satisfy a sum rule; and (3) under findings 1 and 2, there exist an infinite number of constants of motion. As a practical issue, with the use of an AL soliton injected through the incoming bond, we obtain transmission probabilities inversely proportional to the strength of nonlinearity on the outgoing bonds.

Thiobarbiturate and barbiturate salts of pefloxacin drug: Growth, structure, thermal stability and IR-spectra

NASA Astrophysics Data System (ADS)

Golovnev, Nicolay N.; Molokeev, Maxim S.; Lesnikov, Maxim K.; Sterkhova, Irina V.; Atuchin, Victor V.

2017-12-01

Three new salts of pefloxacin (PefH) with thiobarbituric (H2tba) and barbituric (H2ba) acids, pefloxacinium 2-thiobarbiturate trihydrate, PefH2(Htba)·3H2O (1), pefloxacinium 2-thiobarbiturate, PefH2(Htba) (2) and bis(pefloxacinium barbiturate) hydrate, (PefH2)2(Hba)2·2.56H2O (3) are synthesized and structurally characterized by the X-ray single-crystal diffraction. The structures of 1-3 contain intramolecular hydrogen bonds Csbnd H⋯F, Osbnd H⋯O. Intermolecular hydrogen bonds Nsbnd H⋯O and Osbnd H⋯O form a 2D plane network in 1. In 2 and 3, intermolecular hydrogen bonds Nsbnd H⋯O form the infinite chains. In 1-3, the Htba- and Hba- ions are connected with PefH2+ only by one intermolecular hydrogen bond Nsbnd H⋯O. In 2 and 3, two Htba- and Hba- ions are connected by two hydrogen bonds Nsbnd H⋯O. These pairs form infinite chains. All three structures are stabilized by the π-π interactions of the head-to-tail type between PefH2+ ions. Compounds 2 and 3 are characterized by powder XRD, TG-DSC and FT-IR.

SAChES: Scalable Adaptive Chain-Ensemble Sampling.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swiler, Laura Painton; Ray, Jaideep; Ebeida, Mohamed Salah

We present the development of a parallel Markov Chain Monte Carlo (MCMC) method called SAChES, Scalable Adaptive Chain-Ensemble Sampling. This capability is targed to Bayesian calibration of com- putationally expensive simulation models. SAChES involves a hybrid of two methods: Differential Evo- lution Monte Carlo followed by Adaptive Metropolis. Both methods involve parallel chains. Differential evolution allows one to explore high-dimensional parameter spaces using loosely coupled (i.e., largely asynchronous) chains. Loose coupling allows the use of large chain ensembles, with far more chains than the number of parameters to explore. This reduces per-chain sampling burden, enables high-dimensional inversions and the usemore » of computationally expensive forward models. The large number of chains can also ameliorate the impact of silent-errors, which may affect only a few chains. The chain ensemble can also be sampled to provide an initial condition when an aberrant chain is re-spawned. Adaptive Metropolis takes the best points from the differential evolution and efficiently hones in on the poste- rior density. The multitude of chains in SAChES is leveraged to (1) enable efficient exploration of the parameter space; and (2) ensure robustness to silent errors which may be unavoidable in extreme-scale computational platforms of the future. This report outlines SAChES, describes four papers that are the result of the project, and discusses some additional results.« less

Multiscale implementation of infinite-swap replica exchange molecular dynamics.

PubMed

Yu, Tang-Qing; Lu, Jianfeng; Abrams, Cameron F; Vanden-Eijnden, Eric

2016-10-18

Replica exchange molecular dynamics (REMD) is a popular method to accelerate conformational sampling of complex molecular systems. The idea is to run several replicas of the system in parallel at different temperatures that are swapped periodically. These swaps are typically attempted every few MD steps and accepted or rejected according to a Metropolis-Hastings criterion. This guarantees that the joint distribution of the composite system of replicas is the normalized sum of the symmetrized product of the canonical distributions of these replicas at the different temperatures. Here we propose a different implementation of REMD in which (i) the swaps obey a continuous-time Markov jump process implemented via Gillespie's stochastic simulation algorithm (SSA), which also samples exactly the aforementioned joint distribution and has the advantage of being rejection free, and (ii) this REMD-SSA is combined with the heterogeneous multiscale method to accelerate the rate of the swaps and reach the so-called infinite-swap limit that is known to optimize sampling efficiency. The method is easy to implement and can be trivially parallelized. Here we illustrate its accuracy and efficiency on the examples of alanine dipeptide in vacuum and C-terminal β-hairpin of protein G in explicit solvent. In this latter example, our results indicate that the landscape of the protein is a triple funnel with two folded structures and one misfolded structure that are stabilized by H-bonds.

Characterizing quantum phase transition by teleportation

NASA Astrophysics Data System (ADS)

Wu, Meng-He; Ling, Yi; Shu, Fu-Wen; Gan, Wen-Cong

2018-04-01

In this paper we provide a novel way to explore the relation between quantum teleportation and quantum phase transition. We construct a quantum channel with a mixed state which is made from one dimensional quantum Ising chain with infinite length, and then consider the teleportation with the use of entangled Werner states as input qubits. The fidelity as a figure of merit to measure how well the quantum state is transferred is studied numerically. Remarkably we find the first-order derivative of the fidelity with respect to the parameter in quantum Ising chain exhibits a logarithmic divergence at the quantum critical point. The implications of this phenomenon and possible applications are also briefly discussed.

Intermolecular hydrogen bonded and self-assembled β-pleated sheet structures of β-sulfidocarbonyls

NASA Astrophysics Data System (ADS)

Hussain, Sahid; Das, Gopal; Chaudhuri, Mihir K.

2007-06-01

The three crystal structures of β-sulfidocarbonyls 1, 2 and 3 synthesized from the reaction of acryl amide with cystiene, 1,2-dithiol and 1,3-dithiols, respectively, in water catalyzed by borax, have been determined at 273 K. The characteristic features of the structures are self-assembly through intermolecular hydrogen bonding leading to infinite chains of molecules in one direction, in addition to the stacking of layers of such molecular chains in the perpendicular direction ultimately giving rise to β-pleated sheets of 3D molecular network involving N-H⋯O, C-H⋯O and C-H⋯S bonding in the crystal lattice.

Predicting the stability of a compressible periodic parallel jet flow

NASA Technical Reports Server (NTRS)

Miles, Jeffrey H.

1996-01-01

It is known that mixing enhancement in compressible free shear layer flows with high convective Mach numbers is difficult. One design strategy to get around this is to use multiple nozzles. Extrapolating this design concept in a one dimensional manner, one arrives at an array of parallel rectangular nozzles where the smaller dimension is omega and the longer dimension, b, is taken to be infinite. In this paper, the feasibility of predicting the stability of this type of compressible periodic parallel jet flow is discussed. The problem is treated using Floquet-Bloch theory. Numerical solutions to this eigenvalue problem are presented. For the case presented, the interjet spacing, s, was selected so that s/omega =2.23. Typical plots of the eigenvalue and stability curves are presented. Results obtained for a range of convective Mach numbers from 3 to 5 show growth rates omega(sub i)=kc(sub i)/2 range from 0.25 to 0.29. These results indicate that coherent two-dimensional structures can occur without difficulty in multiple parallel periodic jet nozzles and that shear layer mixing should occur with this type of nozzle design.

Influences of the chemical structure of entrainers on the activity coefficients in presence of biodiesel

NASA Astrophysics Data System (ADS)

Mäder, A.; Fleischmann, A.; Fang, Ye; Ruck, W.; Krahl, J.

2012-05-01

In this work we analyzed the strength of the intermolecular forces between biodiesel and the entrainer and their influence on the entrainer's ability to interact with biodiesel. Furthermore we investigated the influence of the chemical structure of an entrainer to the interaction with biodiesel. For this purpose the activity coefficients γ∞ at infinite dilution of acids, aldehydes, ketones and alcohols in biodiesel were measured with the method of headspace gas chromatography (HSGC). Short-chained acids showed the highest interaction of the analyzed entrainers caused by their ability to build hydrogen bonds with biodiesel. Increased chain length of the acids cause reduced interaction with biodiesel, which is mainly due to the higher obstruction of the acid molecule and therefore the reduced ability to build hydrogen bonds with biodiesel. Aldehydes, ketones and alcohols showed lower interaction with biodiesel compared to the acids. Longer-chained alcohols showed increased interaction with biodiesel due to the raised London Forces and an inductive +I effect of the molecule chain.

Thermodynamics of Inozemtsev's elliptic spin chain

NASA Astrophysics Data System (ADS)

Klabbers, Rob

2016-06-01

We study the thermodynamic behaviour of Inozemtsev's long-range elliptic spin chain using the Bethe ansatz equations describing the spectrum of the model in the infinite-length limit. We classify all solutions of these equations in that limit and argue which of these solutions determine the spectrum in the thermodynamic limit. Interestingly, some of the solutions are not selfconjugate, which puts the model in sharp contrast to one of the model's limiting cases, the Heisenberg XXX spin chain. Invoking the string hypothesis we derive the thermodynamic Bethe ansatz equations (TBA-equations) from which we determine the Helmholtz free energy in thermodynamic equilibrium and derive the associated Y-system. We corroborate our results by comparing numerical solutions of the TBA-equations to a direct computation of the free energy for the finite-length hamiltonian. In addition we confirm numerically the interesting conjecture put forward by Finkel and González-López that the original and supersymmetric versions of Inozemtsev's elliptic spin chain are equivalent in the thermodynamic limit.

Half the entanglement in critical systems is distillable from a single specimen

NASA Astrophysics Data System (ADS)

Orús, R.; Latorre, J. I.; Eisert, J.; Cramer, M.

2006-06-01

We establish a quantitative relationship between the entanglement content of a single quantum chain at a critical point and the corresponding entropy of entanglement. We find that, surprisingly, the leading critical scaling of the single-copy entanglement with respect to any bipartitioning is exactly one-half of the entropy of entanglement, in a general setting of conformal field theory and quasifree systems. Conformal symmetry imposes that the single-copy entanglement scales as E1(ρL)=(c/6)lnL-(c/6)(π2/lnL)+O(1/L) , where L is the number of constituents in a block of an infinite chain and c denotes the central charge. This shows that from a single specimen of a critical chain, already half the entanglement can be distilled compared to the rate that is asymptotically available. The result is substantiated by a quantitative analysis for all translationally invariant quantum spin chains corresponding to all isotropic quasifree fermionic models. An example of the XY spin chain shows that away from criticality the above relation is maintained only near the quantum phase transition.

Pit-chain in Noctis Labyrinthus

NASA Image and Video Library

2002-12-20

These pit-chain features in this NASA Mars Odyssey image of south Noctis Labryinthus are oriented parallel to grabens in the area, suggesting that tensional stresses may have been responsible for their formation.

Probability distribution of the entanglement across a cut at an infinite-randomness fixed point

NASA Astrophysics Data System (ADS)

Devakul, Trithep; Majumdar, Satya N.; Huse, David A.

2017-03-01

We calculate the probability distribution of entanglement entropy S across a cut of a finite one-dimensional spin chain of length L at an infinite-randomness fixed point using Fisher's strong randomness renormalization group (RG). Using the random transverse-field Ising model as an example, the distribution is shown to take the form p (S |L ) ˜L-ψ (k ) , where k ≡S /ln[L /L0] , the large deviation function ψ (k ) is found explicitly, and L0 is a nonuniversal microscopic length. We discuss the implications of such a distribution on numerical techniques that rely on entanglement, such as matrix-product-state-based techniques. Our results are verified with numerical RG simulations, as well as the actual entanglement entropy distribution for the random transverse-field Ising model which we calculate for large L via a mapping to Majorana fermions.

Mixed-order phase transition of the contact process near multiple junctions.

PubMed

Juhász, Róbert; Iglói, Ferenc

2017-02-01

We have studied the phase transition of the contact process near a multiple junction of M semi-infinite chains by Monte Carlo simulations. As opposed to the continuous transitions of the translationally invariant (M=2) and semi-infinite (M=1) system, the local order parameter is found to be discontinuous for M>2. Furthermore, the temporal correlation length diverges algebraically as the critical point is approached, but with different exponents on the two sides of the transition. In the active phase, the estimate is compatible with the bulk value, while in the inactive phase it exceeds the bulk value and increases with M. The unusual local critical behavior is explained by a scaling theory with an irrelevant variable, which becomes dangerous in the inactive phase. Quenched spatial disorder is found to make the transition continuous in agreement with earlier renormalization group results.

Chiral Luttinger liquids and a generalized Luttinger's theorem in fractional quantum Hall edges via finite-entanglement scaling

NASA Astrophysics Data System (ADS)

Varjas, Daniel; Zaletel, Michael; Moore, Joel

2014-03-01

We use bosonic field theories and the infinite system density matrix renormalization group (iDMRG) method to study infinite strips of fractional quantum Hall (FQH) states starting from microscopic Hamiltonians. Finite-entanglement scaling allows us to accurately measure chiral central charge, edge mode exponents and momenta without finite-size errors. We analyze states in the first and second level of the standard hierarchy and compare our results to predictions of the chiral Luttinger liquid (χLL) theory. The results confirm the universality of scaling exponents in chiral edges and demonstrate that renormalization is subject to universal relations in the non-chiral case. We prove a generalized Luttinger's theorem involving all singularities in the momentum-resolved density, which naturally arises when mapping Landau levels on a cylinder to a fermion chain and deepens our understanding of non-Fermi liquids in 1D.

Chiral Luttinger liquids and a generalized Luttinger theorem in fractional quantum Hall edges via finite-entanglement scaling

NASA Astrophysics Data System (ADS)

Varjas, Dániel; Zaletel, Michael P.; Moore, Joel E.

2013-10-01

We use bosonic field theories and the infinite system density matrix renormalization group method to study infinite strips of fractional quantum Hall states starting from microscopic Hamiltonians. Finite-entanglement scaling allows us to accurately measure chiral central charge, edge-mode exponents, and momenta without finite-size errors. We analyze states in the first and second levels of the standard hierarchy and compare our results to predictions of the chiral Luttinger liquid theory. The results confirm the universality of scaling exponents in chiral edges and demonstrate that renormalization is subject to universal relations in the nonchiral case. We prove a generalized Luttinger theorem involving all singularities in the momentum-resolved density, which naturally arises when mapping Landau levels on a cylinder to a fermion chain and deepens our understanding of non-Fermi liquids in one dimension.

The effect of magnetic nanoparticle concentration on the structure organisation of a microferrogel

NASA Astrophysics Data System (ADS)

Ryzhkov, A. V.; Melenev, P. V.; Balasoiu, M.; Raikher, Yu L.

2018-03-01

Coarse-grained molecular dynamics simulation is applied to study the structural response of micro-sized magnetopolymer objects – microferrogels (MFG). The results for MFGs with different magnetic properties and concentrations of magnetic filler nanoparticles are analysed to detect the transition between non-aggregated configurations and the states with pronounced chains. The nanoparticles are assumed to be either magnetically isotropic or to possess infinite magnetic anisotropy. It is shown that, depending on the type of the particle anisotropy, an applied field in rather different ways affects the MFG structure and shape. Diagrams describing the degree of aggregation as a function of the parameter of the interparticle magnetodipolar interaction and concentration are presented. In particular, it is found that in the case of infinitely anisotropic nanoparticles the aggregation transitions undergoes via a non-trivial scenario. The effect of the structure transformations on the volume change of the MFG objects is studied as well.

Infinite charge mobility in muscovite at 300 K

NASA Astrophysics Data System (ADS)

Russell, F. Michael; Archilla, Juan F. R.; Frutos, Fabian; Medina-Carrasco, Santiago

2017-11-01

Evidence is presented for infinite charge mobility in natural crystals of muscovite mica at room temperature. Muscovite has a basic layered structure containing a flat monatomic sheet of potassium sandwiched between mirror silicate layers. It is an excellent electrical insulator. Studies of defects in muscovite crystals indicated that positive charge could propagate over great distances along atomic chains in the potassium sheets in the absence of an applied electric potential. The charge moved in association with anharmonic lattice excitations that moved at about sonic speed and created by nuclear recoil of the radioactive isotope 40K. This was verified by measuring currents passing through crystals when irradiated with energetic alpha particles at room temperature. The charge propagated more than 1000 times the range of the alpha particles of average energy and 250 times the range of channelling particles of maximum energy. The range is limited only by size of the crystal.

Morphology of poly-p-xylylene crystallized during polymerization.

NASA Technical Reports Server (NTRS)

Kubo, S.; Wunderlich, B.

1971-01-01

The morphology of as-polymerized poly-p-xylylene grown between -17 and 30 C is found to consist of lame llar alpha crystals oriented with the (010) plane parallel to the support surface. The crystallinity decreases with decreasing polymerization temperature. Spherulitic and nonspherulitic portions of the polymer film consist of folded chain lamellas with the chain axis parallel to the support surface. The results were obtained by small- and wide-angle X-ray measurements, electron and optical microscopy, and differential thermal analysis.

Parallel algorithms for simulating continuous time Markov chains

NASA Technical Reports Server (NTRS)

Nicol, David M.; Heidelberger, Philip

1992-01-01

We have previously shown that the mathematical technique of uniformization can serve as the basis of synchronization for the parallel simulation of continuous-time Markov chains. This paper reviews the basic method and compares five different methods based on uniformization, evaluating their strengths and weaknesses as a function of problem characteristics. The methods vary in their use of optimism, logical aggregation, communication management, and adaptivity. Performance evaluation is conducted on the Intel Touchstone Delta multiprocessor, using up to 256 processors.

Circuit topology of self-interacting chains: implications for folding and unfolding dynamics.

PubMed

Mugler, Andrew; Tans, Sander J; Mashaghi, Alireza

2014-11-07

Understanding the relationship between molecular structure and folding is a central problem in disciplines ranging from biology to polymer physics and DNA origami. Topology can be a powerful tool to address this question. For a folded linear chain, the arrangement of intra-chain contacts is a topological property because rearranging the contacts requires discontinuous deformations. Conversely, the topology is preserved when continuously stretching the chain while maintaining the contact arrangement. Here we investigate how the folding and unfolding of linear chains with binary contacts is guided by the topology of contact arrangements. We formalize the topology by describing the relations between any two contacts in the structure, which for a linear chain can either be in parallel, in series, or crossing each other. We show that even when other determinants of folding rate such as contact order and size are kept constant, this 'circuit' topology determines folding kinetics. In particular, we find that the folding rate increases with the fractions of parallel and crossed relations. Moreover, we show how circuit topology constrains the conformational phase space explored during folding and unfolding: the number of forbidden unfolding transitions is found to increase with the fraction of parallel relations and to decrease with the fraction of series relations. Finally, we find that circuit topology influences whether distinct intermediate states are present, with crossed contacts being the key factor. The approach presented here can be more generally applied to questions on molecular dynamics, evolutionary biology, molecular engineering, and single-molecule biophysics.

Division Algebras, Supersymmetry and Higher Gauge Theory

NASA Astrophysics Data System (ADS)

Huerta, John Gmerek

2011-12-01

Starting from the four normed division algebras---the real numbers, complex numbers, quaternions and octonions, with dimensions k = 1, 2, 4 and 8, respectively---a systematic procedure gives a 3-cocycle on the Poincare Lie superalgebra in dimensions k + 2 = 3, 4, 6 and 10. A related procedure gives a 4-cocycle on the Poincare Lie superalgebra in dimensions k+3 = 4, 5, 7 and 11. The existence of these cocycles follow from certain spinor identities that hold only in these dimensions, and which are closely related to the existence of superstring and super-Yang--Mills theory in dimensions k + 2, and super-2-brane theory in dimensions k + 3. In general, an (n+1)-cocycle on a Lie superalgebra yields a 'Lie n-superalgebra': that is, roughly speaking, an n-term chain complex equipped with a bracket satisfying the axioms of a Lie superalgebra up to chain homotopy. We thus obtain Lie 2-superalgebras extending the Poincare superalgebra in dimensions 3, 4, 6, and 10, and Lie 3-superalgebras extending the Poincare superalgebra in dimensions 4, 5, 7 and 11. As shown in Sati, Schreiber and Stasheff's work on generalized connections valued in Lie n-superalgebras, Lie 2-superalgebra connections describe the parallel transport of strings, while Lie 3-superalgebra connections describe the parallel transport of 2-branes. Moreover, in the octonionic case, these connections concisely summarize the fields appearing in 10- and 11-dimensional supergravity. Generically, integrating a Lie n-superalgebra to a Lie n-supergroup yields a 'Lie n-supergroup' that is hugely infinite-dimensional. However, when the Lie n-superalgebra is obtained from an (n + 1)-cocycle on a nilpotent Lie superalgebra, there is a geometric procedure to integrate the cocycle to one on the corresponding nilpotent Lie supergroup. In general, a smooth (n+1)-cocycle on a supergroup yields a 'Lie n-supergroup': that is, a weak n-group internal to supermanifolds. Using our geometric procedure to integrate the 3-cocycle in dimensions 3, 4, 6 and 10, we obtain a Lie 2-supergroup extending the Poincare supergroup in those dimensions, and similarly integrating the 4-cocycle in dimensions 4, 5, 7 and 11, we obtain a Lie 3-supergroup extending the Poincare supergroup in those dimensions.

High-pressure synthesis and characterization of the first cerium fluoride borate CeB{sub 2}O{sub 4}F

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinteregger, Ernst; Wurst, Klaus; Tribus, Martina

2013-08-15

CeB{sub 2}O{sub 4}F is the first cerium fluoride borate, which is exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO{sub 3}]{sup 3−} groups. This new cerium fluoride borate was synthesized under high-pressure/high-temperature conditions of 0.9 GPa and 1450 °C in a Walker-type multianvil apparatus. The compound crystallizes in the orthorhombic space group Pbca (No. 61) with eight formula units and the lattice parameters a=821.63(5), b=1257.50(9), c=726.71(6) pm, V=750.84(9) Å{sup 3}, R{sub 1}=0.0698, and wR{sub 2}=0.0682 (all data). The structure exhibits a 9+1 coordinated cerium ion, one three-fold coordinated fluoride ion and a one-dimensional chain of [BO{sub 3}]{sup 3−}more » groups. Furthermore, IR spectroscopy, Electron Micro Probe Analysis and temperature-dependent X-ray powder diffraction measurements were performed. - Graphical abstract: A new rare-earth fluoride borate CeB{sub 2}O{sub 4}F could be synthesized under high-pressure/high-temperature conditions of 0.9 °GPa and 1450 °Cin a Walker-type multianvil apparatus. The crystal structure represents a new structure type in the class of rare-earth fluoride borates. The structure exhibits a 9+1 coordinated cerium ion, one three-fold coordinated fluoride ion and a one-dimensional chain of [BO{sub 3}]{sup 3−} groups. A closer view on the ac-plane shows an interesting wave-like modulation of the borate chains. Highlights: • CeB{sub 2}O{sub 4}F is the first fluoride borate exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO{sub 3}]{sup 3−} groups. • CeB{sub 2}O{sub 4}F is the first cerium fluoride borate. • High-pressure conditions were necessary to synthesize CeB{sub 2}O{sub 4}F.« less

Cherenkov radiation due to the passage of an oscillatory dipole moving parallel to a conducting barrier

DOE Office of Scientific and Technical Information (OSTI.GOV)

De, P.K.

1973-08-01

The Cherenkov radiation emitted by an oscillating dipole moving in a semi-infinite dielectric with a constant velocity along a straight line parallel to the conducting boundary is calculated by using Maxwell's equations. The wave nature of electromagnetic intensities reveals that waves propagate in two modes, and the radiation takes place in the form of two cones which are semicircular in section, the axes of the cones coinciding wiih the path of the dipole. Conditions for the existence of only one cone are given. The intensity of radiation fluctuates spatially. The conducting boundary acts as a promoter and plays an importantmore » role in the graduation of energy loss which is technically important for concentration of radiation. (RWR)« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jalas, S.; Dornmair, I.; Lehe, R.

Particle in Cell (PIC) simulations are a widely used tool for the investigation of both laser- and beam-driven plasma acceleration. It is a known issue that the beam quality can be artificially degraded by numerical Cherenkov radiation (NCR) resulting primarily from an incorrectly modeled dispersion relation. Pseudo-spectral solvers featuring infinite order stencils can strongly reduce NCR - or even suppress it - and are therefore well suited to correctly model the beam properties. For efficient parallelization of the PIC algorithm, however, localized solvers are inevitable. Arbitrary order pseudo-spectral methods provide this needed locality. Yet, these methods can again be pronemore » to NCR. Here in this paper, we show that acceptably low solver orders are sufficient to correctly model the physics of interest, while allowing for parallel computation by domain decomposition.« less

Hydration of non-polar anti-parallel β-sheets

NASA Astrophysics Data System (ADS)

Urbic, Tomaz; Dias, Cristiano L.

2014-04-01

In this work we focus on anti-parallel β-sheets to study hydration of side chains and polar groups of the backbone using all-atom molecular dynamics simulations. We show that: (i) water distribution around the backbone does not depend significantly on amino acid sequence, (ii) more water molecules are found around oxygen than nitrogen atoms of the backbone, and (iii) water molecules around nitrogen are highly localized in the planed formed by peptide backbones. To study hydration around side chains we note that anti-parallel β-sheets exhibit two types of cross-strand pairing: Hydrogen-Bond (HB) and Non-Hydrogen-Bond (NHB) pairing. We show that distributions of water around alanine, leucine, and valine side chains are very different at HB compared to NHB faces. For alanine pairs, the space between side chains has a higher concentration of water if residues are located in the NHB face of the β-sheet as opposed to the HB face. For leucine residues, the HB face is found to be dry while the space between side chains at the NHB face alternates between being occupied and non-occupied by water. Surprisingly, for valine residues the NHB face is dry, whereas the HB face is occupied by water. We postulate that these differences in water distribution are related to context dependent propensities observed for β-sheets.

Hydration of non-polar anti-parallel β-sheets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Urbic, Tomaz; Dias, Cristiano L., E-mail: cld@njit.edu

2014-04-28

In this work we focus on anti-parallel β-sheets to study hydration of side chains and polar groups of the backbone using all-atom molecular dynamics simulations. We show that: (i) water distribution around the backbone does not depend significantly on amino acid sequence, (ii) more water molecules are found around oxygen than nitrogen atoms of the backbone, and (iii) water molecules around nitrogen are highly localized in the planed formed by peptide backbones. To study hydration around side chains we note that anti-parallel β-sheets exhibit two types of cross-strand pairing: Hydrogen-Bond (HB) and Non-Hydrogen-Bond (NHB) pairing. We show that distributions ofmore » water around alanine, leucine, and valine side chains are very different at HB compared to NHB faces. For alanine pairs, the space between side chains has a higher concentration of water if residues are located in the NHB face of the β-sheet as opposed to the HB face. For leucine residues, the HB face is found to be dry while the space between side chains at the NHB face alternates between being occupied and non-occupied by water. Surprisingly, for valine residues the NHB face is dry, whereas the HB face is occupied by water. We postulate that these differences in water distribution are related to context dependent propensities observed for β-sheets.« less

Geometric MCMC for infinite-dimensional inverse problems

NASA Astrophysics Data System (ADS)

Beskos, Alexandros; Girolami, Mark; Lan, Shiwei; Farrell, Patrick E.; Stuart, Andrew M.

2017-04-01

Bayesian inverse problems often involve sampling posterior distributions on infinite-dimensional function spaces. Traditional Markov chain Monte Carlo (MCMC) algorithms are characterized by deteriorating mixing times upon mesh-refinement, when the finite-dimensional approximations become more accurate. Such methods are typically forced to reduce step-sizes as the discretization gets finer, and thus are expensive as a function of dimension. Recently, a new class of MCMC methods with mesh-independent convergence times has emerged. However, few of them take into account the geometry of the posterior informed by the data. At the same time, recently developed geometric MCMC algorithms have been found to be powerful in exploring complicated distributions that deviate significantly from elliptic Gaussian laws, but are in general computationally intractable for models defined in infinite dimensions. In this work, we combine geometric methods on a finite-dimensional subspace with mesh-independent infinite-dimensional approaches. Our objective is to speed up MCMC mixing times, without significantly increasing the computational cost per step (for instance, in comparison with the vanilla preconditioned Crank-Nicolson (pCN) method). This is achieved by using ideas from geometric MCMC to probe the complex structure of an intrinsic finite-dimensional subspace where most data information concentrates, while retaining robust mixing times as the dimension grows by using pCN-like methods in the complementary subspace. The resulting algorithms are demonstrated in the context of three challenging inverse problems arising in subsurface flow, heat conduction and incompressible flow control. The algorithms exhibit up to two orders of magnitude improvement in sampling efficiency when compared with the pCN method.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peterson, Steven K

The U.S. Department of Energy (DOE) has a significant programmatic interest in the safe and secure routing and transportation of Spent Nuclear Fuel (SNF) and High Level Waste (HLW) in the United States, including shipments entering the country from locations outside U.S borders. In any shipment of SNF/HLW, there are multiple chains; a jurisdictional chain as the material moves between jurisdictions (state, federal, tribal, administrative), a physical supply chain (which mode), as well as a custody chain (which stakeholder is in charge/possession) of the materials being transported. Given these interconnected networks, there lies vulnerabilities, whether in lack of communication betweenmore » interested stakeholders or physical vulnerabilities such as interdiction. By identifying key links and nodes as well as administrative weaknesses, decisions can be made to harden the physical network and improve communication between stakeholders. This paper examines the parallel chains of oversight and custody as well as the chain of stakeholder interests for the shipments of SNF/HLW and the potential impacts on systemic resiliency. Using the Crystal River shutdown location as well as a hypothetical international shipment brought into the United States, this paper illustrates the parallel chains and maps them out visually.« less

Infinite-disorder critical points of models with stretched exponential interactions

NASA Astrophysics Data System (ADS)

Juhász, Róbert

2014-09-01

We show that an interaction decaying as a stretched exponential function of distance, J(l)˜ e-cl^a , is able to alter the universality class of short-range systems having an infinite-disorder critical point. To do so, we study the low-energy properties of the random transverse-field Ising chain with the above form of interaction by a strong-disorder renormalization group (SDRG) approach. We find that the critical behavior of the model is controlled by infinite-disorder fixed points different from those of the short-range model if 0 < a < 1/2. In this range, the critical exponents calculated analytically by a simplified SDRG scheme are found to vary with a, while, for a > 1/2, the model belongs to the same universality class as its short-range variant. The entanglement entropy of a block of size L increases logarithmically with L at the critical point but, unlike the short-range model, the prefactor is dependent on disorder in the range 0 < a < 1/2. Numerical results obtained by an improved SDRG scheme are found to be in agreement with the analytical predictions. The same fixed points are expected to describe the critical behavior of, among others, the random contact process with stretched exponentially decaying activation rates.

Bayesian tomography by interacting Markov chains

NASA Astrophysics Data System (ADS)

Romary, T.

2017-12-01

In seismic tomography, we seek to determine the velocity of the undergound from noisy first arrival travel time observations. In most situations, this is an ill posed inverse problem that admits several unperfect solutions. Given an a priori distribution over the parameters of the velocity model, the Bayesian formulation allows to state this problem as a probabilistic one, with a solution under the form of a posterior distribution. The posterior distribution is generally high dimensional and may exhibit multimodality. Moreover, as it is known only up to a constant, the only sensible way to addressthis problem is to try to generate simulations from the posterior. The natural tools to perform these simulations are Monte Carlo Markov chains (MCMC). Classical implementations of MCMC algorithms generally suffer from slow mixing: the generated states are slow to enter the stationary regime, that is to fit the observations, and when one mode of the posterior is eventually identified, it may become difficult to visit others. Using a varying temperature parameter relaxing the constraint on the data may help to enter the stationary regime. Besides, the sequential nature of MCMC makes them ill fitted toparallel implementation. Running a large number of chains in parallel may be suboptimal as the information gathered by each chain is not mutualized. Parallel tempering (PT) can be seen as a first attempt to make parallel chains at different temperatures communicate but only exchange information between current states. In this talk, I will show that PT actually belongs to a general class of interacting Markov chains algorithm. I will also show that this class enables to design interacting schemes that can take advantage of the whole history of the chain, by authorizing exchanges toward already visited states. The algorithms will be illustrated with toy examples and an application to first arrival traveltime tomography.

2-(3-Chloro­phen­yl)-4,5-dihydro-1H-imidazole

PubMed Central

Kia, Reza; Fun, Hoong-Kun; Kargar, Hadi

2009-01-01

In the title compound, C9H9ClN2, a substituted imidazoline, the six- and five-membered rings are twisted from each other, making a dihedral angle of 17.07 (5)°. In the crystal structure, a short Cl⋯Cl [3.3540 (3) Å] inter­action is observed. Neighbouring mol­ecules are linked together by inter­molecular N—H⋯N hydrogen bonds into a one-dimensional infinite chain along the [101] direction and short Cl⋯Cl contacts link the chains into a three-dimensional network. There is also a significant π-stacking inter­action between the planar sections of the six- and five-membered rings. PMID:21581940

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vourdas, A.

The finite set of subsystems of a finite quantum system with variables in Z(n), is studied as a Heyting algebra. The physical meaning of the logical connectives is discussed. It is shown that disjunction of subsystems is more general concept than superposition. Consequently, the quantum probabilities related to commuting projectors in the subsystems, are incompatible with associativity of the join in the Heyting algebra, unless if the variables belong to the same chain. This leads to contextuality, which in the present formalism has as contexts, the chains in the Heyting algebra. Logical Bell inequalities, which contain “Heyting factors,” are discussed.more » The formalism is also applied to the infinite set of all finite quantum systems, which is appropriately enlarged in order to become a complete Heyting algebra.« less

The crystal structures of iron and cobalt pyridine (py)–sulfates, [Fe(SO4)(py)4]n and [Co3(SO4)3(py)11]n

PubMed Central

Pham, Duyen N. K.; Roy, Mrittika; Kreider-Mueller, Ava; Golen, James A.; Manke, David R.

2018-01-01

The solid-state structures of two metal–pyridine–sulfate compounds, namely catena-poly[[tetra­kis­(pyridine-κN)iron(II)]-μ-sulfato-κ2 O:O′], [Fe(SO4)(C5H5N)4]n, (1), and catena-poly[[tetra­kis­(pyridine-κN)cobalt(II)]-μ-sulfato-κ2 O:O′-[tetra­kis­(pyridine-κN)cobalt(II)]-μ-sulfato-κ3 O,O′:O′′-[tris­(pyridine-κN)cobalt(II)]-μ-sulfato-κ2 O:O′], [Co3(SO4)3(C5H5N)11]n, (2), are reported. The iron compound (1) displays a polymeric structure, with infinite chains of FeII atoms adopting octa­hedral N4O2 coordination environments that involve four pyridine ligands and two bridging sulfate ligands. The cobalt compound (2) displays a polymeric structure, with infinite chains of CoII atoms. Two of the three Co centers have an octa­hedral N4O2 coordination environment that involves four pyridine ligands and two bridging sulfate ligands. The third Co center has an octa­hedral N3O3 coordination environment that involves three pyridine ligands, and two bridging sulfate ligands with one sulfate chelating the cobalt atom.

Structures of nitrato-(2-hydroxybenzaldehydo) (2,2 Prime -bipyridyl)copper and nitrato-(2-hydroxy-5-nitrobenzaldehydo)(2,2 Prime -bipyridyl)copper

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chumakov, Yu. M.; Paladi, L. G.; Antosyak, B. Ya.

2011-03-15

Nitrato-(2-hydroxy-5-nitrobenzaldehydo)(2,2 Prime -bipyridyl)copper (I) and nitrato-(2-hydroxybenzaldehydo)(2,2 Prime -bipyridyl)copper (II) were synthesized and characterized by X-ray diffraction. The coordination polyhedron of the central copper atom in complex I can be described as a distorted tetragonal pyramid whose base is formed by the phenol and carbonyl oxygen atoms of the monodeprotonated 2-hydroxy-5nitrobenzaldehyde molecule and the nitrogen atoms of the 2,2 Prime -bipyridyl ligand and whose apex is occupied by the oxygen atom of the nitrato group. In the crystal structure, complexes I are linked by the acido ligands and the NO{sub 2} groups of the aldehyde molecule into infinite chains. In complexmore » II, the central copper atom is coordinated by 2-hydroxybenzaldehyde, 2,2 Prime -bipyridyl, and the nitrato group, resulting in the formation of centrosymmetric dimers. The coordination polyhedron of the central copper atom can be described as a bipyramid (4 + 1 + 1) with the same base as in complex I. The axial vertices of the bipyramid are occupied by the oxygen atom of the nitrato group and the bridging phenol oxygen atom of the adjacent complex related to the initial complex by a center of symmetry. In the crystal structure, complexes II are hydrogen bonded into infinite chains.« less

Formation and evolution of bubbly screens in confined oscillating bubbly liquids.

PubMed

Shklyaev, Sergey; Straube, Arthur V

2010-01-01

We consider the dynamics of dilute monodisperse bubbly liquid confined by two plane solid walls and subject to small-amplitude high-frequency oscillations normal to the walls. The initial state corresponds to the uniform distribution of bubbles and motionless liquid. The period of external driving is assumed much smaller than typical relaxation times for a single bubble but larger than the period of volume eigenoscillations. The time-averaged description accounting for the two-way coupling between the liquid and the bubbles is applied. We show that the model predicts accumulation of bubbles in thin sheets parallel to the walls. These singular structures, which are formally characterized by infinitely thin width and infinitely high concentration, are referred to as bubbly screens. The formation of a bubbly screen is described analytically in terms of a self-similar solution, which is in agreement with numerical simulations. We study the evolution of bubbly screens and detect a one-dimensional stationary state, which is shown to be unconditionally unstable.

Modeling and control of flexible structures

NASA Technical Reports Server (NTRS)

Gibson, J. S.; Mingori, D. L.

1988-01-01

This monograph presents integrated modeling and controller design methods for flexible structures. The controllers, or compensators, developed are optimal in the linear-quadratic-Gaussian sense. The performance objectives, sensor and actuator locations and external disturbances influence both the construction of the model and the design of the finite dimensional compensator. The modeling and controller design procedures are carried out in parallel to ensure compatibility of these two aspects of the design problem. Model reduction techniques are introduced to keep both the model order and the controller order as small as possible. A linear distributed, or infinite dimensional, model is the theoretical basis for most of the text, but finite dimensional models arising from both lumped-mass and finite element approximations also play an important role. A central purpose of the approach here is to approximate an optimal infinite dimensional controller with an implementable finite dimensional compensator. Both convergence theory and numerical approximation methods are given. Simple examples are used to illustrate the theory.

Formation and evolution of bubbly screens in confined oscillating bubbly liquids

NASA Astrophysics Data System (ADS)

Shklyaev, Sergey; Straube, Arthur V.

2010-01-01

We consider the dynamics of dilute monodisperse bubbly liquid confined by two plane solid walls and subject to small-amplitude high-frequency oscillations normal to the walls. The initial state corresponds to the uniform distribution of bubbles and motionless liquid. The period of external driving is assumed much smaller than typical relaxation times for a single bubble but larger than the period of volume eigenoscillations. The time-averaged description accounting for the two-way coupling between the liquid and the bubbles is applied. We show that the model predicts accumulation of bubbles in thin sheets parallel to the walls. These singular structures, which are formally characterized by infinitely thin width and infinitely high concentration, are referred to as bubbly screens. The formation of a bubbly screen is described analytically in terms of a self-similar solution, which is in agreement with numerical simulations. We study the evolution of bubbly screens and detect a one-dimensional stationary state, which is shown to be unconditionally unstable.

Electromagnetic radiation from filamentary sources in the presence of axially magnetized cylindrical plasma scatterers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Es’kin, V. A.; Ivoninsky, A. V.; Kudrin, A. V., E-mail: kud@rf.unn.ru

Electromagnetic radiation from filamentary electric-dipole and magnetic-current sources of infinite length in the presence of gyrotropic cylindrical scatterers in the surrounding free space is studied. The scatterers are assumed to be infinitely long, axially magnetized circular plasma columns parallel to the axis of the filamentary source. The field and the radiation pattern of each source are calculated in the case where the source frequency is equal to one of the surface plasmon resonance frequencies of the cylindrical scatterers. It is shown that the presence of even a single resonant magnetized plasma scatterer of small electrical radius or a few suchmore » scatterers significantly affects the total fields of the filamentary sources, so that their radiation patterns become essentially different from those in the absence of scatterers or the presence of isotropic scatterers of the same shape and size. It is concluded that the radiation characteristics of the considered sources can efficiently be controlled using their resonance interaction with the neighboring gyrotropic scatterers.« less

Analysis of the electromagnetic scattering from an inlet geometry with lossy walls

NASA Technical Reports Server (NTRS)

Myung, N. H.; Pathak, P. H.; Chunang, C. D.

1985-01-01

One of the primary goals is to develop an approximate but sufficiently accurate analysis for the problem of electromagnetic (EM) plane wave scattering by an open ended, perfectly-conducting, semi-infinite hollow circular waveguide (or duct) with a thin, uniform layer of lossy or absorbing material on its inner wall, and with a simple termination inside. The less difficult but useful problem of the EM scattering by a two-dimensional (2-D), semi-infinite parallel plate waveguide with an impedance boundary condition on the inner walls was chosen initially for analysis. The impedance boundary condition in this problem serves to model a thin layer of lossy dielectric/ferrite coating on the otherwise perfectly-conducting interior waveguide walls. An approximate but efficient and accurate ray solution was obtained recently. That solution is presently being extended to the case of a moderately thick dielectric/ferrite coating on the walls so as to be valid for situations where the impedance boundary condition may not remain sufficiently accurate.

Frustrated magnetism in the spin–chain metal Yb 2Fe 12P 7

DOE PAGES

Baumbach, Ryan E.; Hamlin, James J.; Janoschek, Marc; ...

2016-01-08

Here, magnetization measurements for magnetic fieldsmore » $${{\\mu}_{0}}H$$ up to 60 T are reported for the noncentrosymmetric spin–chain metal Yb 2Fe 12P 7. These measurements reveal behavior that is consistent with Ising-like spin chain magnetism that produces pronounced spin degeneracy. In particular, we find that although a Brillouin field dependence is observed in M( H) for $$H\\bot ~c$$ with a saturation moment that is close to the expected value for free ions of Yb 3+, non-Brillouin-like behavior is seen for $$H~\\parallel ~c$$ with an initial saturation moment that is nearly half the free ion value. In addition, hysteretic behavior that extends above the ordering temperature $${{T}_{\\text{M}}}$$ is seen for $$H~\\parallel ~c$$ but not for $$H~\\bot ~c$$ , suggesting out-of-equilibrium physics. This point of view is strengthened by the observation of a spin reconfiguration in the ordered state for $$H~\\parallel ~c$$ which is only seen for $$T\\leqslant {{T}_{\\text{M}}}$$ and after polarizing the spins. Together with the heat capacity data, these results suggest that the anomalous low temperature phenomena that were previously reported are driven by spin degeneracy that is related to the Ising-like one dimensional chain-like configuration of the Yb ions.« less

The cognitive architecture for chaining of two mental operations.

PubMed

Sackur, Jérôme; Dehaene, Stanislas

2009-05-01

A simple view, which dates back to Turing, proposes that complex cognitive operations are composed of serially arranged elementary operations, each passing intermediate results to the next. However, whether and how such serial processing is achieved with a brain composed of massively parallel processors, remains an open question. Here, we study the cognitive architecture for chained operations with an elementary arithmetic algorithm: we required participants to add (or subtract) two to a digit, and then compare the result with five. In four experiments, we probed the internal implementation of this task with chronometric analysis, the cued-response method, the priming method, and a subliminal forced-choice procedure. We found evidence for an approximately sequential processing, with an important qualification: the second operation in the algorithm appears to start before completion of the first operation. Furthermore, initially the second operation takes as input the stimulus number rather than the output of the first operation. Thus, operations that should be processed serially are in fact executed partially in parallel. Furthermore, although each elementary operation can proceed subliminally, their chaining does not occur in the absence of conscious perception. Overall, the results suggest that chaining is slow, effortful, imperfect (resulting partly in parallel rather than serial execution) and dependent on conscious control.

Interaction of CO with an Au monatomic chain at different strains: Electronic structure and ballistic transport

NASA Astrophysics Data System (ADS)

Sclauzero, Gabriele; Dal Corso, Andrea; Smogunov, Alexander

2012-04-01

We study the energetics, the electronic structure, and the ballistic transport of an infinite Au monatomic chain with an adsorbed CO molecule. We find that the bridge adsorption site is energetically favored with respect to the atop site, both at the equilibrium Au-Au spacing of the chain and at larger spacings. Instead, a substitutional configuration requires a very elongated Au-Au bond, well above the rupture distance of the pristine Au chain. The electronic structure properties can be described by the Blyholder model, which involves the formation of bonding/antibonding pairs of 5σ and 2π states through the hybridization between molecular levels of CO and metallic states of the chain. In the atop geometry, we find an almost vanishing conductance due to the 5σ antibonding states giving rise to a Fano-like destructive interference close to the Fermi energy. In the bridge geometry, instead, the same states are shifted to higher energies and the conductance reduction with respect to pristine Au chain is much smaller. We also examine the effects of strain on the ballistic transport, finding opposite behaviors for the atop and bridge conductances. Only the bridge geometry shows a strain dependence compatible with the experimental conductance traces.

Polymerase chain reaction system

DOEpatents

Benett, William J.; Richards, James B.; Stratton, Paul L.; Hadley, Dean R.; Milanovich, Fred P.; Belgrader, Phil; Meyer, Peter L.

2004-03-02

A portable polymerase chain reaction DNA amplification and detection system includes one or more chamber modules. Each module supports a duplex assay of a biological sample. Each module has two parallel interrogation ports with a linear optical system. The system is capable of being handheld.

Parallel O(log n) algorithms for open- and closed-chain rigid multibody systems based on a new mass matrix factorization technique

NASA Technical Reports Server (NTRS)

Fijany, Amir

1993-01-01

In this paper, parallel O(log n) algorithms for computation of rigid multibody dynamics are developed. These parallel algorithms are derived by parallelization of new O(n) algorithms for the problem. The underlying feature of these O(n) algorithms is a drastically different strategy for decomposition of interbody force which leads to a new factorization of the mass matrix (M). Specifically, it is shown that a factorization of the inverse of the mass matrix in the form of the Schur Complement is derived as M(exp -1) = C - B(exp *)A(exp -1)B, wherein matrices C, A, and B are block tridiagonal matrices. The new O(n) algorithm is then derived as a recursive implementation of this factorization of M(exp -1). For the closed-chain systems, similar factorizations and O(n) algorithms for computation of Operational Space Mass Matrix lambda and its inverse lambda(exp -1) are also derived. It is shown that these O(n) algorithms are strictly parallel, that is, they are less efficient than other algorithms for serial computation of the problem. But, to our knowledge, they are the only known algorithms that can be parallelized and that lead to both time- and processor-optimal parallel algorithms for the problem, i.e., parallel O(log n) algorithms with O(n) processors. The developed parallel algorithms, in addition to their theoretical significance, are also practical from an implementation point of view due to their simple architectural requirements.

Accurate modeling of plasma acceleration with arbitrary order pseudo-spectral particle-in-cell methods

DOE PAGES

Jalas, S.; Dornmair, I.; Lehe, R.; ...

2017-03-20

Particle in Cell (PIC) simulations are a widely used tool for the investigation of both laser- and beam-driven plasma acceleration. It is a known issue that the beam quality can be artificially degraded by numerical Cherenkov radiation (NCR) resulting primarily from an incorrectly modeled dispersion relation. Pseudo-spectral solvers featuring infinite order stencils can strongly reduce NCR - or even suppress it - and are therefore well suited to correctly model the beam properties. For efficient parallelization of the PIC algorithm, however, localized solvers are inevitable. Arbitrary order pseudo-spectral methods provide this needed locality. Yet, these methods can again be pronemore » to NCR. Here in this paper, we show that acceptably low solver orders are sufficient to correctly model the physics of interest, while allowing for parallel computation by domain decomposition.« less

Linear-scaling density-functional simulations of charged point defects in Al2O3 using hierarchical sparse matrix algebra.

PubMed

Hine, N D M; Haynes, P D; Mostofi, A A; Payne, M C

2010-09-21

We present calculations of formation energies of defects in an ionic solid (Al(2)O(3)) extrapolated to the dilute limit, corresponding to a simulation cell of infinite size. The large-scale calculations required for this extrapolation are enabled by developments in the approach to parallel sparse matrix algebra operations, which are central to linear-scaling density-functional theory calculations. The computational cost of manipulating sparse matrices, whose sizes are determined by the large number of basis functions present, is greatly improved with this new approach. We present details of the sparse algebra scheme implemented in the ONETEP code using hierarchical sparsity patterns, and demonstrate its use in calculations on a wide range of systems, involving thousands of atoms on hundreds to thousands of parallel processes.

An Exactly Soluble Model for Hopping Particles Moving with Correlations Between States due to Exchange Sites

NASA Astrophysics Data System (ADS)

Zhao, Xian-Geng; Jia, Sue-Tang

1992-09-01

The motion of hopping particles on an infinite chain is investigated. The model is characterized by the correlations between states due to exchange sites. The analytic solutions for this system are discussed in general case. For some special cases, exact results are obtained with the help of explicit calculations of propagators and mean square displacement deviation. Both probability propagators for the creation and annihilation of two particles or for the deformation and formation of Frenkel excitons are indicated.

8-Hydr­oxy-5,6,7-trimeth­oxy-2-phenyl-4H-chromen-4-one

PubMed Central

Theodoro, Jahyr E.; Santos, Djalma; Pérez, Hiram; da Silva, Maria Fátima das Graças Fernandes; Ellena, J.

2008-01-01

In the title compound, C18H16O6, the benzopyran group is essentially planar, with the O atoms of the substituent groups lying close to its mean plane. The mol­ecular conformation is governed by intra­molecular inter­actions. The crystal packing is mainly determined by one classical inter­molecular hydrogen bond which gives rise to the formation of an infinite chain along the a axis. PMID:21202382

A parallel algorithm for step- and chain-growth polymerization in molecular dynamics.

PubMed

de Buyl, Pierre; Nies, Erik

2015-04-07

Classical Molecular Dynamics (MD) simulations provide insight into the properties of many soft-matter systems. In some situations, it is interesting to model the creation of chemical bonds, a process that is not part of the MD framework. In this context, we propose a parallel algorithm for step- and chain-growth polymerization that is based on a generic reaction scheme, works at a given intrinsic rate and produces continuous trajectories. We present an implementation in the ESPResSo++ simulation software and compare it with the corresponding feature in LAMMPS. For chain growth, our results are compared to the existing simulation literature. For step growth, a rate equation is proposed for the evolution of the crosslinker population that compares well to the simulations for low crosslinker functionality or for short times.

A parallel algorithm for step- and chain-growth polymerization in molecular dynamics

NASA Astrophysics Data System (ADS)

de Buyl, Pierre; Nies, Erik

2015-04-01

Classical Molecular Dynamics (MD) simulations provide insight into the properties of many soft-matter systems. In some situations, it is interesting to model the creation of chemical bonds, a process that is not part of the MD framework. In this context, we propose a parallel algorithm for step- and chain-growth polymerization that is based on a generic reaction scheme, works at a given intrinsic rate and produces continuous trajectories. We present an implementation in the ESPResSo++ simulation software and compare it with the corresponding feature in LAMMPS. For chain growth, our results are compared to the existing simulation literature. For step growth, a rate equation is proposed for the evolution of the crosslinker population that compares well to the simulations for low crosslinker functionality or for short times.

Ionizable side chains at catalytic active sites of enzymes.

PubMed

Jimenez-Morales, David; Liang, Jie; Eisenberg, Bob

2012-05-01

Catalytic active sites of enzymes of known structure can be well defined by a modern program of computational geometry. The CASTp program was used to define and measure the volume of the catalytic active sites of 573 enzymes in the Catalytic Site Atlas database. The active sites are identified as catalytic because the amino acids they contain are known to participate in the chemical reaction catalyzed by the enzyme. Acid and base side chains are reliable markers of catalytic active sites. The catalytic active sites have 4 acid and 5 base side chains, in an average volume of 1,072 Å(3). The number density of acid side chains is 8.3 M (in chemical units); the number density of basic side chains is 10.6 M. The catalytic active site of these enzymes is an unusual electrostatic and steric environment in which side chains and reactants are crowded together in a mixture more like an ionic liquid than an ideal infinitely dilute solution. The electrostatics and crowding of reactants and side chains seems likely to be important for catalytic function. In three types of analogous ion channels, simulation of crowded charges accounts for the main properties of selectivity measured in a wide range of solutions and concentrations. It seems wise to use mathematics designed to study interacting complex fluids when making models of the catalytic active sites of enzymes.

Ionizable Side Chains at Catalytic Active Sites of Enzymes

PubMed Central

Jimenez-Morales, David; Liang, Jie

2012-01-01

Catalytic active sites of enzymes of known structure can be well defined by a modern program of computational geometry. The CASTp program was used to define and measure the volume of the catalytic active sites of 573 enzymes in the Catalytic Site Atlas database. The active sites are identified as catalytic because the amino acids they contain are known to participate in the chemical reaction catalyzed by the enzyme. Acid and base side chains are reliable markers of catalytic active sites. The catalytic active sites have 4 acid and 5 base side chains, in an average volume of 1072 Å3. The number density of acid side chains is 8.3 M (in chemical units); the number density of basic side chains is 10.6 M. The catalytic active site of these enzymes is an unusual electrostatic and steric environment in which side chains and reactants are crowded together in a mixture more like an ionic liquid than an ideal infinitely dilute solution. The electrostatics and crowding of reactants and side chains seems likely to be important for catalytic function. In three types of analogous ion channels, simulation of crowded charges accounts for the main properties of selectivity measured in a wide range of solutions and concentrations. It seems wise to use mathematics designed to study interacting complex fluids when making models of the catalytic active sites of enzymes. PMID:22484856

Parallel and serial grouping of image elements in visual perception.

PubMed

Houtkamp, Roos; Roelfsema, Pieter R

2010-12-01

The visual system groups image elements that belong to an object and segregates them from other objects and the background. Important cues for this grouping process are the Gestalt criteria, and most theories propose that these are applied in parallel across the visual scene. Here, we find that Gestalt grouping can indeed occur in parallel in some situations, but we demonstrate that there are also situations where Gestalt grouping becomes serial. We observe substantial time delays when image elements have to be grouped indirectly through a chain of local groupings. We call this chaining process incremental grouping and demonstrate that it can occur for only a single object at a time. We suggest that incremental grouping requires the gradual spread of object-based attention so that eventually all the object's parts become grouped explicitly by an attentional labeling process. Our findings inspire a new incremental grouping theory that relates the parallel, local grouping process to feedforward processing and the serial, incremental grouping process to recurrent processing in the visual cortex.

Generalized analytical solutions to sequentially coupled multi-species advective-dispersive transport equations in a finite domain subject to an arbitrary time-dependent source boundary condition

NASA Astrophysics Data System (ADS)

Chen, Jui-Sheng; Liu, Chen-Wuing; Liang, Ching-Ping; Lai, Keng-Hsin

2012-08-01

SummaryMulti-species advective-dispersive transport equations sequentially coupled with first-order decay reactions are widely used to describe the transport and fate of the decay chain contaminants such as radionuclide, chlorinated solvents, and nitrogen. Although researchers attempted to present various types of methods for analytically solving this transport equation system, the currently available solutions are mostly limited to an infinite or a semi-infinite domain. A generalized analytical solution for the coupled multi-species transport problem in a finite domain associated with an arbitrary time-dependent source boundary is not available in the published literature. In this study, we first derive generalized analytical solutions for this transport problem in a finite domain involving arbitrary number of species subject to an arbitrary time-dependent source boundary. Subsequently, we adopt these derived generalized analytical solutions to obtain explicit analytical solutions for a special-case transport scenario involving an exponentially decaying Bateman type time-dependent source boundary. We test the derived special-case solutions against the previously published coupled 4-species transport solution and the corresponding numerical solution with coupled 10-species transport to conduct the solution verification. Finally, we compare the new analytical solutions derived for a finite domain against the published analytical solutions derived for a semi-infinite domain to illustrate the effect of the exit boundary condition on coupled multi-species transport with an exponential decaying source boundary. The results show noticeable discrepancies between the breakthrough curves of all the species in the immediate vicinity of the exit boundary obtained from the analytical solutions for a finite domain and a semi-infinite domain for the dispersion-dominated condition.

Efficient dynamic simulation for multiple chain robotic mechanisms

NASA Technical Reports Server (NTRS)

Lilly, Kathryn W.; Orin, David E.

1989-01-01

An efficient O(mN) algorithm for dynamic simulation of simple closed-chain robotic mechanisms is presented, where m is the number of chains, and N is the number of degrees of freedom for each chain. It is based on computation of the operational space inertia matrix (6 x 6) for each chain as seen by the body, load, or object. Also, computation of the chain dynamics, when opened at one end, is required, and the most efficient algorithm is used for this purpose. Parallel implementation of the dynamics for each chain results in an O(N) + O(log sub 2 m+1) algorithm.

Infinite hidden conditional random fields for human behavior analysis.

PubMed

Bousmalis, Konstantinos; Zafeiriou, Stefanos; Morency, Louis-Philippe; Pantic, Maja

2013-01-01

Hidden conditional random fields (HCRFs) are discriminative latent variable models that have been shown to successfully learn the hidden structure of a given classification problem (provided an appropriate validation of the number of hidden states). In this brief, we present the infinite HCRF (iHCRF), which is a nonparametric model based on hierarchical Dirichlet processes and is capable of automatically learning the optimal number of hidden states for a classification task. We show how we learn the model hyperparameters with an effective Markov-chain Monte Carlo sampling technique, and we explain the process that underlines our iHCRF model with the Restaurant Franchise Rating Agencies analogy. We show that the iHCRF is able to converge to a correct number of represented hidden states, and outperforms the best finite HCRFs--chosen via cross-validation--for the difficult tasks of recognizing instances of agreement, disagreement, and pain. Moreover, the iHCRF manages to achieve this performance in significantly less total training, validation, and testing time.

Synthesis, Structure and bonding Analysis of the Polar Intermetallic Phase Ca2Pt2Cd

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samal, Saroj L.; Corbett, John D.

The polar intermetallic phase Ca2Pt2Cd was discovered during explorations of the Ca-Pt-Cd system. The compound was synthesized by high temperature reactions, and its structure refined by single-crystal X-ray diffraction as orthorhombic, Immm, a = 4.4514(5), b = 5.8415(6), c = 8.5976(9) Å, Z = 2. The structure formally contains infinite, planar networks of [Pt2Cd]4– along the ab plane, which can be described as tessellation of six and four-member rings of the anions, with cations stuffed between the anion layers. The infinite condensed platinum chains show a substantial long–short distortion of 0.52 Å, an appreciable difference between Ca2Pt2Cd (26 valence electrons)more » and the isotypic but regular Ca2Cu2Ga (29 VE). The relatively large cation proportion diminishes the usual dominance of polar (Pt–Cd) and 5d–5d (Pt–Pt) contributions to the total Hamilton populations.« less

Targeted energy transfers and passive acoustic wave redirection in a two-dimensional granular network under periodic excitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yijing, E-mail: yzhng123@illinois.edu; Moore, Keegan J.; Vakakis, Alexander F.

2015-12-21

We study passive pulse redirection and nonlinear targeted energy transfer in a granular network composed of two semi-infinite, ordered homogeneous granular chains mounted on linear elastic foundations and coupled by weak linear stiffnesses. Periodic excitation in the form of repetitive half-sine pulses is applied to one of the chains, designated as the “excited chain,” whereas the other chain is initially at rest and is regarded as the “absorbing chain.” We show that passive pulse redirection and targeted energy transfer from the excited to the absorbing chain can be achieved by macro-scale realization of the spatial analog of the Landau-Zener quantummore » tunneling effect. This is realized by finite stratification of the elastic foundation of the excited chain and depends on the system parameters (e.g., the percentage of stratification) and on the parameters of the periodic excitation. Utilizing empirical mode decomposition and numerical Hilbert transforms, we detect the existence of two distinct nonlinear phenomena in the periodically forced network; namely, (i) energy localization in the absorbing chain due to sustained 1:1 resonance capture leading to irreversible pulse redirection from the excited chain, and (ii) continuous energy exchanges in the form of nonlinear beats between the two chains in the absence of resonance capture. Our results extend previous findings of transient passive energy redirection in impulsively excited granular networks and demonstrate that steady state passive pulse redirection in these networks can be robustly achieved under periodic excitation.« less

Heat conduction in diatomic chains with correlated disorder

NASA Astrophysics Data System (ADS)

Savin, Alexander V.; Zolotarevskiy, Vadim; Gendelman, Oleg V.

2017-01-01

The paper considers heat transport in diatomic one-dimensional lattices, containing equal amounts of particles with different masses. Ordering of the particles in the chain is governed by single correlation parameter - the probability for two neighboring particles to have the same mass. As this parameter grows from zero to unity, the structure of the chain varies from regular staggering chain to completely random configuration, and then - to very long clusters of particles with equal masses. Therefore, this correlation parameter allows a control of typical cluster size in the chain. In order to explore different regimes of the heat transport, two interatomic potentials are considered. The first one is an infinite potential wall, corresponding to instantaneous elastic collisions between the neighboring particles. In homogeneous chains such interaction leads to an anomalous heat transport. The other one is classical Lennard-Jones interatomic potential, which leads to a normal heat transport. The simulations demonstrate that the correlated disorder of the particle arrangement does not change the convergence properties of the heat conduction coefficient, but essentially modifies its value. For the collision potential, one observes essential growth of the coefficient for fixed chain length as the limit of large homogeneous clusters is approached. The thermal transport in these models remains superdiffusive. In the Lennard-Jones chain the effect of correlation appears to be not monotonous in the limit of low temperatures. This behavior stems from the competition between formation of long clusters mentioned above, and Anderson localization close to the staggering ordered state.

Solvothermal syntheses and characterization of three new silver(I)/copper(I)-thioarsenates based on As2+/As3+ ions

NASA Astrophysics Data System (ADS)

Yao, Hua-Gang; Tang, Cheng-Fei; An, Yong-Lin; Ou, Zi-Jian; Wu, Guo-Hao; Lan, Pei; Zheng, Yi-Long

2017-02-01

Three new silver(I)/copper(I)-thioarsenates KAgAsIIS2 (1), RbCu2AsIIIS3 (2) and RbCu4AsIIIS4 (3) have been solvothermally synthesized and structurally characterized. 1 exhibits a two-dimensional anionic network built up by As-As bond connecting the left- and right-handed helical [AgS2]4- chains, and represents the first examples of thioarsenates(II). The structure of 2 consists of two kinds of helical [Cu2S3]4- chains linked by the arsenic atoms to form double layers with rubidium ions between the layers. Compound 3 is built up of infinite [Cu2S2]2- chain and layered [Cu6As2S6] linked to form a three-dimensional anionic framework, [Cu4AsS4]-, and containing channels in which the rubidium cations reside. The optical properties of 1-3 have been investigated by UV-vis spectroscopy.

Large bond-dimension time-evolution block decimation study of the XXZ quantum spin chains of S = 1/2 and 1

NASA Astrophysics Data System (ADS)

Choi, Hwan Bin; Lee, Ji-Woo

2017-09-01

We study quantum phase transitions of a XXZ spin model with spin S = 1/2 and 1 in one dimension. The XXZ spin chain is one of basic models in understanding various one-dimensional magnetic materials. To study this model, we construct infinite-lattice matrix product state (iMPS), which is a tensor product form for a one-dimensional many-body quantum wave function. By using timeevolution- block-decimation method (TEBD) on iMPS, we obtain the ground states of the XXZ model at zero temperature. This method is very delicate in calculating ground states so that we developed a reliable method of finding the ground state with the dimension of entanglement coefficients up to 300, which is beyond the previous works. By analyzing ground-state energies, half-chain entanglement entropies, and entanglement spectrum, we found the signatures of quantum phase transitions between ferromagnetic phase, XY phase, Haldane phase, and antiferromagnetic phase.

Seismic anisotropy and large-scale deformation of the Eastern Alps

NASA Astrophysics Data System (ADS)

Bokelmann, Götz; Qorbani, Ehsan; Bianchi, Irene

2013-12-01

Mountain chains at the Earth's surface result from deformation processes within the Earth. Such deformation processes can be observed by seismic anisotropy, via the preferred alignment of elastically anisotropic minerals. The Alps show complex deformation at the Earth's surface. In contrast, we show here that observations of seismic anisotropy suggest a relatively simple pattern of internal deformation. Together with earlier observations from the Western Alps, the SKS shear-wave splitting observations presented here show one of the clearest examples yet of mountain chain-parallel fast orientations worldwide, with a simple pattern nearly parallel to the trend of the mountain chain. In the Eastern Alps, the fast orientations do not connect with neighboring mountain chains, neither the present-day Carpathians, nor the present-day Dinarides. In that region, the lithosphere is thin and the observed anisotropy thus resides within the asthenosphere. The deformation is consistent with the eastward extrusion toward the Pannonian basin that was previously suggested based on seismicity and surface geology.

Anisotropic upper critical magnetic fields in Rb 2 Cr 3 As 3 superconductor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Zhang-Tu; Liu, Yi; Bao, Jin-Ke

Rb2Cr3As3 is a structurally one-dimensional superconductor containing Cr3As3 chains with a superconducting transition temperature of T-c = 4.8 K. Here we report the electrical resistance measurements for Rb2Cr3As3 single crystals, under magnetic fields up to 29.5 T and at temperatures down to 0.36 K, from which the upper critical fields, H-c2(T), can be obtained in a broad temperature range. For field parallel to the Cr3As3 chains, H-c2(parallel to)(T) is paramagnetically limited with an initial slope of mu(0)dH(c2)(parallel to)/dT|T-c = - 16 T K-1 and a zero-temperature upper critical field of mu H-0(c2)parallel to(0) = 17.5 T. For field perpendicular tomore » the Cr3As3 chains, however, H-c2(perpendicular to)(T) is only limited by orbital pair-breaking effect with mu(0)dH(c2)(perpendicular to)/dT|(Tc) = - 3 T K-1. As a consequence, the anisotropy gamma H = H-c2(parallel to)/H-c2(perpendicular to) decreases sharply near T-c and reverses below 2 K. Remarkably, the low- temperature H-c2(perpendicular to)(T) down to 0.075 T-c remains to increase linearly up to over three times the Pauli paramagnetic limit, which strongly suggests dominant spin-triplet superconductivity in Rb2Cr3As3.« less

The Mendeleev Crater chain: A description and discussion of origin

NASA Technical Reports Server (NTRS)

Eppler, D.; Heiken, G.

1974-01-01

A 113-kilometer-long crater chain on the floor of Mendeleev Crater is the best morphological example of several similar chains on the lunar far side. Age relationships relative to Mendeleev Crater indicate that it is a younger feature that may have developed over a fault parallel to the lunar grid system. The dumbbell shape of the chain may be related to a differential stress along a fault crossing the floor that resulted in varying resistance to magma invasion.

Pressure-induced stable BeN4 as a high-energy density material

NASA Astrophysics Data System (ADS)

Zhang, Shoutao; Zhao, Ziyuan; Liu, Lulu; Yang, Guochun

2017-10-01

Polynitrogens are the ideal rocket fuels or propellants. Due to strong triple N≡N bond in N2, the direct polymerization of nitrogen is rather difficult (i.e. extreme high temperature and high pressure). However, the use of nitrides as precursors or the reaction of N2 with other elements has been proved to be an effective way to obtain polynitrogens. Here, with assistance of the advanced first-principles swarm-intelligence structure searches, we found that P 1 bar -BeN4, containing infinite zigzag-like polymeric nitrogen chains, can be synthesized by compressing the mixture of Be3N2 and N2 at 25.4 GPa, which is greatly lower than 110 GPa for synthesizing cubic gauche nitrogen and other polynitrogen compounds (e.g. bulk CNO at 52 GPa and SN4 at 49 GPa). Its structural stability can be attributed to the coexistence of ionic Be-N and covalent N-N bonds. Intriguingly, this phase has high kinetic stability and remains metastable at ambient pressure. The exceptional properties, including high energy density (3.60 kJ g-1), high nitrogen content (86.1%), high dynamical stability, and low polymerization pressure, make P 1 bar -structured BeN4 a promising high energy material. Infinite nitrogen chains in P 1 bar -BeN4 transform to N10 rings network in P21/c phase at 115.1 GPa. P 1 bar -BeN4 is metallic, while P21/c-BeN4 is an insulator.

Theoretical and computational studies of excitons in conjugated polymers

NASA Astrophysics Data System (ADS)

Barford, William; Bursill, Robert J.; Smith, Richard W.

2002-09-01

We present a theoretical and computational analysis of excitons in conjugated polymers. We use a tight-binding model of π-conjugated electrons, with 1/r interactions for large r. In both the weak-coupling limit (defined by W>>U) and the strong-coupling limit (defined by W<

Probing amyloid fibril formation of the NFGAIL peptide by computer simulations

NASA Astrophysics Data System (ADS)

Melquiond, Adrien; Gelly, Jean-Christophe; Mousseau, Normand; Derreumaux, Philippe

2007-02-01

Amyloid fibril formation, as observed in Alzheimer's disease and type II diabetes, is currently described by a nucleation-condensation mechanism, but the details of the process preceding the formation of the nucleus are still lacking. In this study, using an activation-relaxation technique coupled to a generic energy model, we explore the aggregation pathways of 12 chains of the hexapeptide NFGAIL. The simulations show, starting from a preformed parallel dimer and ten disordered chains, that the peptides form essentially amorphous oligomers or more rarely ordered β-sheet structures where the peptides adopt a parallel orientation within the sheets. Comparison between the simulations indicates that a dimer is not a sufficient seed for avoiding amorphous aggregates and that there is a critical threshold in the number of connections between the chains above which exploration of amorphous aggregates is preferred.

The structure of denisovite, a fibrous nanocrystalline polytypic disordered ‘very complex’ silicate, studied by a synergistic multi-disciplinary approach employing methods of electron crystallography and X-ray powder diffraction

PubMed Central

Schowalter, Marco; Schmidt, Martin U.; Czank, Michael; Depmeier, Wulf; Rosenauer, Andreas

2017-01-01

Denisovite is a rare mineral occurring as aggregates of fibres typically 200–500 nm diameter. It was confirmed as a new mineral in 1984, but important facts about its chemical formula, lattice parameters, symmetry and structure have remained incompletely known since then. Recently obtained results from studies using microprobe analysis, X-ray powder diffraction (XRPD), electron crystallography, modelling and Rietveld refinement will be reported. The electron crystallography methods include transmission electron microscopy (TEM), selected-area electron diffraction (SAED), high-angle annular dark-field imaging (HAADF), high-resolution transmission electron microscopy (HRTEM), precession electron diffraction (PED) and electron diffraction tomography (EDT). A structural model of denisovite was developed from HAADF images and later completed on the basis of quasi-kinematic EDT data by ab initio structure solution using direct methods and least-squares refinement. The model was confirmed by Rietveld refinement. The lattice parameters are a = 31.024 (1), b = 19.554 (1) and c = 7.1441 (5) Å, β = 95.99 (3)°, V = 4310.1 (5) Å3 and space group P12/a1. The structure consists of three topologically distinct dreier silicate chains, viz. two xonotlite-like dreier double chains, [Si6O17]10−, and a tubular loop-branched dreier triple chain, [Si12O30]12−. The silicate chains occur between three walls of edge-sharing (Ca,Na) octahedra. The chains of silicate tetrahedra and the octahedra walls extend parallel to the z axis and form a layer parallel to (100). Water molecules and K+ cations are located at the centre of the tubular silicate chain. The latter also occupy positions close to the centres of eight-membered rings in the silicate chains. The silicate chains are geometrically constrained by neighbouring octahedra walls and present an ambiguity with respect to their z position along these walls, with displacements between neighbouring layers being either Δz = c/4 or −c/4. Such behaviour is typical for polytypic sequences and leads to disorder along [100]. In fact, the diffraction pattern does not show any sharp reflections with l odd, but continuous diffuse streaks parallel to a* instead. Only reflections with l even are sharp. The diffuse scattering is caused by (100) nano­lamellae separated by stacking faults and twin boundaries. The structure can be described according to the order–disorder (OD) theory as a stacking of layers parallel to (100). PMID:28512570

Comparison of the crystal structures of methyl 4-bromo-2-(meth-oxy-meth-oxy)benzoate and 4-bromo-3-(meth-oxy-meth-oxy)benzoic acid.

PubMed

Suchetan, P A; Suneetha, V; Naveen, S; Lokanath, N K; Krishna Murthy, P

2016-04-01

The title compounds, C10H11BrO4, (I), and C9H9BrO4, (II), are derivatives of bromo-hy-droxy-benzoic acids. Compound (II) crystallizes with two independent mol-ecules (A and B) in the asymmetric unit. In both (I) and (II), the O-CH2-O-CH3 side chain is not in its fully extended conformation; the O-C-O-C torsion angle is 67.3 (3) ° in (I), and -65.8 (3) and -74.1 (3)° in mol-ecules A and B, respectively, in compound (II). In the crystal of (I), mol-ecules are linked by C-H⋯O hydrogen bonds, forming C(5) chains along [010]. The chains are linked by short Br⋯O contacts [3.047 (2) Å], forming sheets parallel to the bc plane. The sheets are linked via C-H⋯π inter-actions, forming a three-dimensional architecture. In the crystal of (II), mol-ecules A and B are linked to form R 2 (2)(8) dimers via two strong O-H⋯O hydrogen bonds. These dimers are linked into ⋯A-B⋯A-B⋯A-B⋯ [C 2 (2)(15)] chains along [011] by C-H⋯O hydrogen bonds. The chains are linked by slipped parallel π-π inter-actions [inter-centroid distances = 3.6787 (18) and 3.8431 (17) Å], leading to the formation of slabs parallel to the bc plane.

Near-ridge seamount chains in the northeastern Pacific Ocean

NASA Astrophysics Data System (ADS)

Clague, David A.; Reynolds, Jennifer R.; Davis, Alicé S.

2000-07-01

High-resolution bathymetry and side-scan data of the Vance, President Jackson, and Taney near-ridge seamount chains in the northeast Pacific were collected with a hull-mounted 30-kHz sonar. The central volcanoes in each chain consist of truncated cone-shaped volcanoes with steep sides and nearly flat tops. Several areas are characterized by frequent small eruptions that result in disorganized volcanic regions with numerous small cones and volcanic ridges but no organized truncated conical structure. Several volcanoes are crosscut by ridge-parallel faults, showing that they formed within 30-40 km of the ridge axis where ridge-parallel faulting is still active. Magmas that built the volcanoes were probably transported through the crust along active ridge-parallel faults. The volcanoes range in volume from 11 to 187 km3, and most have one or more multiple craters and calderas that modify their summits and flanks. The craters (<1 km diameter) and calderas (>1 km diameter) range from small pit craters to calderas as large as 6.5×8.5 km, although most are 2-4 km across. Crosscutting relationships commonly show a sequence of calderas stepping toward the ridge axis. The calderas overlie crustal magma chambers at least as large as those that underlie Kilauea and Mauna Loa Volcanoes in Hawaii, perhaps 4-5 km in diameter and ˜1-3 km below the surface. The nearly flat tops of many of the volcanoes have remnants of centrally located summit shields, suggesting that their flat tops did not form from eruptions along circumferential ring faults but instead form by filling and overflowing of earlier large calderas. The lavas retain their primitive character by residing in such chambers for only short time periods prior to eruption. Stored magmas are withdrawn, probably as dikes intruded into the adjacent ocean crust along active ridge-parallel faults, triggering caldera collapse, or solidified before the next batch of magma is intruded into the volcano, probably 1000-10,000 years later. The chains are oriented parallel to subaxial asthenospheric flow rather than absolute or relative plate motion vectors. The subaxial asthenospheric flow model yields rates of volcanic migration of 3.4, 3.3 and 5.9 cm yr-1 for the Vance, President Jackson, and Taney Seamounts, respectively. The modeled lifespans of the individual volcanoes in the three chains vary from 75 to 95 kyr. These lifespans, coupled with the geologic observations based on the bathymetry, allow us to construct models of magma supply through time for the volcanoes in the three chains.

Rapid optimization of tension distribution for cable-driven parallel manipulators with redundant cables

NASA Astrophysics Data System (ADS)

Ouyang, Bo; Shang, Weiwei

2016-03-01

The solution of tension distributions is infinite for cable-driven parallel manipulators(CDPMs) with redundant cables. A rapid optimization method for determining the optimal tension distribution is presented. The new optimization method is primarily based on the geometry properties of a polyhedron and convex analysis. The computational efficiency of the optimization method is improved by the designed projection algorithm, and a fast algorithm is proposed to determine which two of the lines are intersected at the optimal point. Moreover, a method for avoiding the operating point on the lower tension limit is developed. Simulation experiments are implemented on a six degree-of-freedom(6-DOF) CDPM with eight cables, and the results indicate that the new method is one order of magnitude faster than the standard simplex method. The optimal distribution of tension distribution is thus rapidly established on real-time by the proposed method.

A real time, FEM based optimal control algorithm and its implementation using parallel processing hardware (transistors) in a microprocessor environment

NASA Technical Reports Server (NTRS)

Patten, William Neff

1989-01-01

There is an evident need to discover a means of establishing reliable, implementable controls for systems that are plagued by nonlinear and, or uncertain, model dynamics. The development of a generic controller design tool for tough-to-control systems is reported. The method utilizes a moving grid, time infinite element based solution of the necessary conditions that describe an optimal controller for a system. The technique produces a discrete feedback controller. Real time laboratory experiments are now being conducted to demonstrate the viability of the method. The algorithm that results is being implemented in a microprocessor environment. Critical computational tasks are accomplished using a low cost, on-board, multiprocessor (INMOS T800 Transputers) and parallel processing. Progress to date validates the methodology presented. Applications of the technique to the control of highly flexible robotic appendages are suggested.

Radiant Heat Transfer Between Nongray Parallel Plates of Tungsten

NASA Technical Reports Server (NTRS)

Branstetter, J. Robert

1961-01-01

Net radiant heat flow between two infinite, parallel, tungsten plates was computed by summing the monochromatic energy exchange; the results are graphically presented as a function of the temperatures of the two surfaces. In general these fluxes range from approximately a to 25 percent greater than the results of gray-body computations based on the same emissivity data. The selection of spectral emissivity data and the computational procedure are discussed. The present analytical procedure is so arranged that, as spectral emissivity data for a material become available, these data can be readily introduced into the NASA data-reduction equipment, which has been programmed to compute the net heat flux for the particular geometry and basic assumptions cited in the text. Nongray-body computational techniques for determining radiant heat flux appear practical provided the combination of select spectral emissivity data and the proper mechanized data-reduction equipment are brought to bear on the problem.

Softening of the stiffness of bottle-brush polymers by mutual interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolisetty, S.; Airaud, C.; Rosenfeldt, S.

2007-04-15

We study bottle-brush macromolecules in a good solvent by small-angle neutron scattering (SANS), static light scattering (SLS), and dynamic light scattering (DLS). These polymers consist of a linear backbone to which long side chains are chemically grafted. The backbone contains about 1600 monomer units (weight average) and every second monomer unit carries side chains with approximately 60 monomer units. The SLS and SANS data extrapolated to infinite dilution lead to the form factor of the polymer that can be described in terms of a wormlike chain with a contour length of 380 nm and a persistence length of 17.5 nm.more » An analysis of the DLS data confirms these model parameters. The scattering intensities taken at finite concentration can be modeled using the polymer reference interaction site model. It reveals a softening of the bottle-brush polymers caused by their mutual interaction. We demonstrate that the persistence decreases from 17.5 nm down to 5 nm upon increasing the concentration from dilute solution to the highest concentration (40.59 g/l) under consideration. The observed softening of the chains is comparable to the theoretically predicted decrease of the electrostatic persistence length of linear polyelectrolyte chains at finite concentrations.« less

Spatial data analytics on heterogeneous multi- and many-core parallel architectures using python

USGS Publications Warehouse

Laura, Jason R.; Rey, Sergio J.

2017-01-01

Parallel vector spatial analysis concerns the application of parallel computational methods to facilitate vector-based spatial analysis. The history of parallel computation in spatial analysis is reviewed, and this work is placed into the broader context of high-performance computing (HPC) and parallelization research. The rise of cyber infrastructure and its manifestation in spatial analysis as CyberGIScience is seen as a main driver of renewed interest in parallel computation in the spatial sciences. Key problems in spatial analysis that have been the focus of parallel computing are covered. Chief among these are spatial optimization problems, computational geometric problems including polygonization and spatial contiguity detection, the use of Monte Carlo Markov chain simulation in spatial statistics, and parallel implementations of spatial econometric methods. Future directions for research on parallelization in computational spatial analysis are outlined.

Redirection and Splitting of Sound Waves by a Periodic Chain of Thin Perforated Cylindrical Shells

NASA Astrophysics Data System (ADS)

Bozhko, Andrey; Sánchez-Dehesa, José; Cervera, Francisco; Krokhin, Arkadii

2017-06-01

The scattering of sound by finite and infinite chains of equally spaced perforated metallic cylindrical shells in an ideal (inviscid) and viscous fluid is theoretically studied using rigorous analytical and numerical approaches. Because of perforations, a chain of thin shells is practically transparent for sound within a wide range of frequencies. It is shown that strong scattering and redirection of sound by 90° may occur only for a discrete set of frequencies (Wood's anomalies) where the leaky eigenmodes are excited. The spectrum of eigenmodes consists of antisymmetric and symmetric branches with normal and anomalous dispersion, respectively. The antisymmetric eigenmode turns out to be a deaf mode, since it cannot be excited at normal incidence. However, at slightly oblique incidence, both modes can be resonantly excited at different but close frequencies. The symmetric mode, due to its anomalous dispersion, scatters sound in the "wrong" direction. This property may find an application for the splitting of the two resonant harmonics of the incoming signal into two beams propagating along the chain in the opposite directions. A chain of perforated cylinders may also be used as a passive antenna that detects the direction to the incoming signal by measuring the frequencies of the waves excited in the chain. Calculations are presented for aluminum shells in viscous air where the effects of anomalous scattering, redirection, and signal splitting are well manifested.

Electroosmotic flow in a rectangular channel with variable wall zeta-potential: comparison of numerical simulation with asymptotic theory.

PubMed

Datta, Subhra; Ghosal, Sandip; Patankar, Neelesh A

2006-02-01

Electroosmotic flow in a straight micro-channel of rectangular cross-section is computed numerically for several situations where the wall zeta-potential is not constant but has a specified spatial variation. The results of the computation are compared with an earlier published asymptotic theory based on the lubrication approximation: the assumption that any axial variations take place on a long length scale compared to a characteristic channel width. The computational results are found to be in excellent agreement with the theory even when the scale of axial variations is comparable to the channel width. In the opposite limit when the wavelength of fluctuations is much shorter than the channel width, the lubrication theory fails to describe the solution either qualitatively or quantitatively. In this short wave limit the solution is well described by Ajdari's theory for electroosmotic flow between infinite parallel plates (Ajdari, A., Phys. Rev. E 1996, 53, 4996-5005.) The infinitely thin electric double layer limit is assumed in the theory as well as in the simulation.

A hydrodynamic mechanism for spontaneous formation of ordered drop arrays in confined shear flow

NASA Astrophysics Data System (ADS)

Singha, Sagnik; Zurita-Gotor, Mauricio; Loewenberg, Michael; Migler, Kalman; Blawzdziewicz, Jerzy

2017-11-01

It has been experimentally demonstrated that a drop monolayer driven by a confined shear flow in a Couette device can spontaneously arrange into a flow-oriented parallel chain microstructure. However, the hydrodynamic mechanism of this puzzling self-assembly phenomenon has so far eluded explanation. In a recent publication we suggested that the observed spontaneous drop ordering may arise from hydrodynamic interparticle interactions via a far-field quadrupolar Hele-Shaw flow associated with drop deformation. To verify this conjecture we have developed a simple numerical-simulation model that includes the far-field Hele-Shaw flow quadrupoles and a near-field short-range repulsion. Our simulations show that an initially disordered particle configuration self-organizes into a system of particle chains, similar to the experimentally observed drop-chain structures. The initial stage of chain formation is fast; subsequently, microstructural defects in a partially ordered system are removed by slow annealing, leading to an array of equally spaced parallel chains with a small number of defects. The microstructure evolution is analyzed using angular and spatial order parameters and correlation functions. Supported by NSF Grants No. CBET 1603627 and CBET 1603806.

On the existence of a high-temperature polymorph of Na2Ca6Si4O15—implications for the phase equilibria in the system Na2O-CaO-SiO2

NASA Astrophysics Data System (ADS)

Kahlenberg, Volker; Maier, Matthias

2016-12-01

Singe crystals of a new high-temperature polymorph of Na2Ca6Si4O15 have been obtained from solid state reactions performed at 1300 °C. The basic crystallographic data of this so-called β-phase at ambient conditions are as follows: space group P1 c1, a = 9.0112(5) Å, b = 7.3171(5) Å, c = 10.9723(6) Å, β = 107.720(14)°, V = 689.14(7) Å3, Z = 2. The crystals showed twinning by reticular merohedry (mimicking an orthorhombic C-centred unit cell) which was accounted for during data processing and structure solution. Structure determination was accomplished by direct methods. Least-squares refinements resulted in a residual of R(|F|) = 0.043 for 5811 observed reflections with I > 2σ(I). From a structural point of view β-Na2Ca6Si4O15 can be attributed to the group of mixed-anion silicates containing [Si2O7]-dimers as well as isolated [SiO4]-tetrahedra in the ratio 1:2, i.e. more precisely the formula can be written as Na2Ca6[SiO4]2[Si2O7]. The tetrahedral groups are arranged in layers parallel to (100). Sodium and calcium cations are located between the silicate anions for charge compensation and are coordinated by six to eight nearest oxygen ligands. Alternatively, the structure can be described as a mixed tetrahedral-octahedral framework based on kröhnkite-type [Ca(SiO4)2O2]-chains in which the CaO6-octahedra are corner-linked to bridging SiO4-tetrahedra. The infinite chains are running parallel to [001] and are concentrated in layers parallel to (010). Adjacent layers are shifted relative to each other by an amount of +δ or -δ along a*. Consequently, a …ABABAB… stacking sequence is created. A detailed comparison with related structures such as α-Na2Ca6Si4O15 and other A2B6Si4O15 representatives including topological as well as group theoretical aspects is presented. There are strong indications that monoclinic Na2Ca3Si2O8 mentioned in earlier studies is actually misinterpreted β-Na2Ca6Si4O15. In addition to the detailed crystallographic analysis of the previously unknown compound our results will also help to improve the interpretation of the phase relationships between the compounds in the ternary system Na2O-CaO-SiO2 which are of interest for several applications related to the field of applied mineralogy and materials science.

Thermoreversible gelation of poly(vinylidene fluoride) in phthalates: the influence of aliphatic chain length of solvents.

PubMed

Yadav, P Jaya Prakash; Ghosh, Goutam; Maiti, Biswajit; Aswal, Vinod K; Goyal, P S; Maiti, Pralay

2008-04-17

Thermoreversible gelation of poly(vinylidene fluoride) (PVDF) has been studied in a new series of solvents (phthalates), for example, dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), and dihexyl phthalate (DHP) as a function of temperature and polymer concentration, both by test tube tilting and dynamic light scattering (DLS) method. The effect of aliphatic chain length (n) of diesters on the gelation kinetics, structure/microstructure and morphology of PVDF gels has been examined. Gelation rate was found to increase with increasing aliphatic chain length of diester. DLS results indicate that the sol-gel transformation proceeds via two-steps: first, microgel domains were formed, and then the infinite three-dimensional (3D) network is established by connecting microgels through polymer chains. The crystallites are responsible for 3D network for gelation in phthalates, and alpha-polymorph is formed during gelation producing higher amount of crystallinity with increasing aliphatic chain length of diester. Morphology of the networks of dried gels in different phthalates showed that fibril thickness and lateral dimensions decrease with higher homologues of phthalates. The scattering intensity is fitted with Debye-Bueche model in small-angle neutron scattering and suggested that both the correlation length and interlamellar spacing increases with n. A model has been proposed, based on electronic structure calculations, to explain the conformation of PVDF chain in presence of various phthalates and their complexes, which offer the cause of higher gelation rate for longer aliphatic chain length.

Entanglement spreading after a geometric quench in quantum spin chains

NASA Astrophysics Data System (ADS)

Alba, Vincenzo; Heidrich-Meisner, Fabian

2014-08-01

We investigate the entanglement spreading in the anisotropic spin-1/2 Heisenberg (XXZ) chain after a geometric quench. This corresponds to a sudden change of the geometry of the chain or, in the equivalent language of interacting fermions confined in a box trap, to a sudden increase of the trap size. The entanglement dynamics after the quench is associated with the ballistic propagation of a magnetization wave front. At the free fermion point (XX chain), the von Neumann entropy SA exhibits several intriguing dynamical regimes. Specifically, at short times a logarithmic increase is observed, similar to local quenches. This is accurately described by an analytic formula that we derive from heuristic arguments. At intermediate times partial revivals of the short-time dynamics are superposed with a power-law increase SA˜tα, with α <1. Finally, at very long times a steady state develops with constant entanglement entropy, apart from oscillations. As expected, since the model is integrable, we find that the steady state is nonthermal, although it exhibits extensive entanglement entropy. We also investigate the entanglement dynamics after the quench from a finite to the infinite chain (sudden expansion). While at long times the entanglement vanishes, we demonstrate that its relaxation dynamics exhibits a number of scaling properties. Finally, we discuss the short-time entanglement dynamics in the XXZ chain in the gapless phase. The same formula that describes the time dependence for the XX chain remains valid in the whole gapless phase.

Synthesis and crystal structure of two new uranyl oxychloro-vanadate layered compounds: M7(UO 2) 8(VO 4) 2O 8Cl with M=Rb, Cs

NASA Astrophysics Data System (ADS)

Duribreux, I.; Saadi, M.; Obbade, S.; Dion, C.; Abraham, F.

2003-05-01

Two new alkali uranyl oxychloro vanadates M7(UO 2) 8(VO 4) 2O 8Cl with M=Rb, Cs, have been synthesized by solid-state reactions and their structures determined from single-crystal X-ray diffraction data. They crystallize in the orthorhombic system with space groups Pmcn and Pmmn, respectively. The a and b unit cell parameters are almost identical in both compounds while the c parameter in the Rb compound is doubled: Rb— a=21.427(5) Å, b=11.814(3) Å, c=14.203(3) Å, V=3595.1(1) Å 3, Z=4, ρmes=5.93(2) g/cm 3, ρcal=5.82(1) g/cm 3; Cs— a=21.458(3) Å, b=11.773(2) Å, c=7.495(1) Å, V=1893.6(5) Å 3, Z=2, ρmes=6.09(2) g/cm 3, ρcal=6.11(1) g/cm 3. A full-matrix least-squares refinement yielded R1=0.0221, w R2=0.0562 for 2675 independent reflections and R1=0.0386, w R2=0.1042 for 2446 independent reflections, for the Rb and Cs compounds, respectively. Data were collected with Mo( Kα) radiation and a charge coupled device (CCD) detector of a Bruker diffractometer. Both structures are characterized by [(UO 2) 8(VO 4) 2O 8Cl] n7 n- layers parallel to the (001) plane. The layers are built up from VO 4 tetrahedra, UO 7 and UO 6Cl pentagonal bipyramids, and UO 6 distorded octahedra. The UO 7 and UO 6Cl pentagonal bipyramids are associated by sharing opposite equatorial edges to form infinite chains (UO 5-UO 4Cl-UO 5) n parallel to the a axis. These chains are linked together by VO 4 tetrahedra, UO 6 octahedra, UO 7 corner sharing and UO 6Cl, Cl sharing. Both structures differ simply by the symmetry of the layers. The unit cell contains one centrosymmetric layer in the Cs compound, whereas in the two-layer unit cell of the Rb compound, two non-centrosymmetric consecutive layers are related by an inversion center. The layers appear to be held together by the alkali ions. The mobility of the M+ ions within the interlayer space in M7(UO 2) 8(VO 4) 2O 8Cl and carnotite analog compounds is compared.

Universal scaling for the quantum Ising chain with a classical impurity

NASA Astrophysics Data System (ADS)

Apollaro, Tony J. G.; Francica, Gianluca; Giuliano, Domenico; Falcone, Giovanni; Palma, G. Massimo; Plastina, Francesco

2017-10-01

We study finite-size scaling for the magnetic observables of an impurity residing at the end point of an open quantum Ising chain with transverse magnetic field, realized by locally rescaling the field by a factor μ ≠1 . In the homogeneous chain limit at μ =1 , we find the expected finite-size scaling for the longitudinal impurity magnetization, with no specific scaling for the transverse magnetization. At variance, in the classical impurity limit μ =0 , we recover finite scaling for the longitudinal magnetization, while the transverse one basically does not scale. We provide both analytic approximate expressions for the magnetization and the susceptibility as well as numerical evidences for the scaling behavior. At intermediate values of μ , finite-size scaling is violated, and we provide a possible explanation of this result in terms of the appearance of a second, impurity-related length scale. Finally, by going along the standard quantum-to-classical mapping between statistical models, we derive the classical counterpart of the quantum Ising chain with an end-point impurity as a classical Ising model on a square lattice wrapped on a half-infinite cylinder, with the links along the first circle modified as a function of μ .

A vast amount of various invariant tori in the Nosé-Hoover oscillator.

PubMed

Wang, Lei; Yang, Xiao-Song

2015-12-01

This letter restudies the Nosé-Hoover oscillator. Some new averagely conservative regions are found, each of which is filled with different sequences of nested tori with various knot types. Especially, the dynamical behaviors near the border of "chaotic region" and conservative regions are studied showing that there exist more complicated and thinner invariant tori around the boundaries of conservative regions bounded by tori. Our results suggest an infinite number of island chains in a "chaotic sea" for the Nosé-Hoover oscillator.

A TBA approach to thermal transport in the XXZ Heisenberg model

NASA Astrophysics Data System (ADS)

Zotos, X.

2017-10-01

We show that the thermal Drude weight and magnetothermal coefficient of the 1D easy-plane Heisenberg model can be evaluated by an extension of the Bethe ansatz thermodynamics formulation by Takahashi and Suzuki (1972 Prog. Theor. Phys. 48 2187). They have earlier been obtained by the quantum transfer matrix method (Klümper 1999 Z. Phys. B 91 507). Furthermore, this approach can be applied to the study of the far-out of equilibrium energy current generated at the interface between two semi-infinite chains held at different temperatures.

Electron-phonon interaction in quantum transport through quantum dots and molecular systems

NASA Astrophysics Data System (ADS)

Ojeda, J. H.; Duque, C. A.; Laroze, D.

2016-12-01

The quantum transport and effects of decoherence properties are studied in quantum dots systems and finite homogeneous chains of aromatic molecules connected to two semi-infinite leads. We study these systems based on the tight-binding approach through Green's function technique within a real space renormalization and polaron transformation schemes. In particular, we calculate the transmission probability following the Landauer-Büttiker formalism, the I - V characteristics and the noise power of current fluctuations taken into account the decoherence. Our results may explain the inelastic effects through nanoscopic systems.

A vast amount of various invariant tori in the Nosé-Hoover oscillator

NASA Astrophysics Data System (ADS)

Wang, Lei; Yang, Xiao-Song

2015-12-01

This letter restudies the Nosé-Hoover oscillator. Some new averagely conservative regions are found, each of which is filled with different sequences of nested tori with various knot types. Especially, the dynamical behaviors near the border of "chaotic region" and conservative regions are studied showing that there exist more complicated and thinner invariant tori around the boundaries of conservative regions bounded by tori. Our results suggest an infinite number of island chains in a "chaotic sea" for the Nosé-Hoover oscillator.

A vast amount of various invariant tori in the Nosé-Hoover oscillator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lei; Department of Mathematics and Physics, Hefei University, Hefei 230601; Yang, Xiao-Song, E-mail: yangxs@hust.edu.cn

2015-12-15

This letter restudies the Nosé-Hoover oscillator. Some new averagely conservative regions are found, each of which is filled with different sequences of nested tori with various knot types. Especially, the dynamical behaviors near the border of “chaotic region” and conservative regions are studied showing that there exist more complicated and thinner invariant tori around the boundaries of conservative regions bounded by tori. Our results suggest an infinite number of island chains in a “chaotic sea” for the Nosé-Hoover oscillator.

FPGA-based protein sequence alignment : A review

NASA Astrophysics Data System (ADS)

Isa, Mohd. Nazrin Md.; Muhsen, Ku Noor Dhaniah Ku; Saiful Nurdin, Dayana; Ahmad, Muhammad Imran; Anuar Zainol Murad, Sohiful; Nizam Mohyar, Shaiful; Harun, Azizi; Hussin, Razaidi

2017-11-01

Sequence alignment have been optimized using several techniques in order to accelerate the computation time to obtain the optimal score by implementing DP-based algorithm into hardware such as FPGA-based platform. During hardware implementation, there will be performance challenges such as the frequent memory access and highly data dependent in computation process. Therefore, investigation in processing element (PE) configuration where involves more on memory access in load or access the data (substitution matrix, query sequence character) and the PE configuration time will be the main focus in this paper. There are various approaches to enhance the PE configuration performance that have been done in previous works such as by using serial configuration chain and parallel configuration chain i.e. the configuration data will be loaded into each PEs sequentially and simultaneously respectively. Some researchers have proven that the performance using parallel configuration chain has optimized both the configuration time and area.

An obstacle to building a time machine

NASA Astrophysics Data System (ADS)

Carroll, Sean M.; Farhi, Edward; Guth, Alan H.

1992-01-01

Gott (1991) has shown that a spacetime with two infinite parallel cosmic strings passing each other with sufficient velocity contains closed timelike curves. An attempt to build such a time machine is discussed. Using the energy-momentum conservation laws in the equivalent (2 + 1)-dimensional theory, the spacetime representing the decay of one gravitating particle into two is explicitly constructed; there is never enough mass in an open universe to build the time machine from the products of decays of stationary particles. More generally, the Gott time machine cannot exist in any open (2 + 1)-dimensional universe for which the total momentum is timelike.

1+1 dimensional compactifications of string theory.

PubMed

Goheer, Naureen; Kleban, Matthew; Susskind, Leonard

2004-05-14

We argue that stable, maximally symmetric compactifications of string theory to 1+1 dimensions are in conflict with holography. In particular, the finite horizon entropies of the Rindler wedge in 1+1 dimensional Minkowski and anti-de Sitter space, and of the de Sitter horizon in any dimension, are inconsistent with the symmetries of these spaces. The argument parallels one made recently by the same authors, in which we demonstrated the incompatibility of the finiteness of the entropy and the symmetries of de Sitter space in any dimension. If the horizon entropy is either infinite or zero, the conflict is resolved.

Magnon localization and Bloch oscillations in finite Heisenberg spin chains in an inhomogeneous magnetic field.

PubMed

Kosevich, Yuriy A; Gann, Vladimir V

2013-06-19

We study the localization of magnon states in finite defect-free Heisenberg spin-1/2 ferromagnetic chains placed in an inhomogeneous magnetic field with a constant spatial gradient. Continuous transformation from the extended magnon states to the localized Wannier-Zeeman states in a finite spin chain placed in an inhomogeneous field is described both analytically and numerically. We describe for the first time the non-monotonic dependence of the energy levels of magnons, both long and short wavelength, on the magnetic field gradient, which is a consequence of magnon localization in a finite spin chain. We show that, in contrast to the destruction of the magnon band and the establishment of the Wannier-Stark ladder in a vanishingly small field gradient in an infinite chain, the localization of magnon states at the chain ends preserves the memory of the magnon band. Essentially, the localization at the lower- or higher-field chain end resembles the localization of the positive- or negative-effective-mass band quasiparticles. We also show how the beat dynamics of coherent superposition of extended spin waves in a finite chain in a homogeneous or weakly inhomogeneous field transforms into magnon Bloch oscillations of the superposition of localized Wannier-Zeeman states in a strongly inhomogeneous field. We provide a semiclassical description of the magnon Bloch oscillations and show that the correspondence between the quantum and semiclassical descriptions is most accurate for Bloch oscillations of the magnon coherent states, which are built from a coherent superposition of a large number of the nearest-neighbour Wannier-Zeeman states.

The Epistemological Chain: Practical Applications in Sports

ERIC Educational Resources Information Center

Grecic, David; Collins, Dave

2013-01-01

This article highlights the role of personal epistemology in decision-making and proposes the construct of an epistemological chain (EC) to support this process in the domain of sports coaching. First, the EC is outlined using examples from education and other parallel disciplines. What it looks like to sports coaches is then described, and its…

Sharp organic interface of molecular C60 chains and a pentacene derivative SAM on Au(788): A combined STM & DFT study

NASA Astrophysics Data System (ADS)

Wang, Jun; Tang, Jian-Ming; Larson, Amanda M.; Miller, Glen P.; Pohl, Karsten

2013-12-01

Controlling the molecular structure of the donor-acceptor interface is essential to overcoming the efficiency bottleneck in organic photovoltaics. We present a study of self-assembled fullerene (C60) molecular chains on perfectly ordered 6,13-dichloropentacene (DCP) monolayers forming on a vicinal Au(788) surface using scanning tunneling microscopy in conjunction with density functional theory calculations. DCP is a novel pentacene derivative optimized for photovoltaic applications. The molecules form a brick-wall patterned centered rectangular lattice with the long axis parallel to the monatomic steps that separate the 3.9 nm wide Au(111) terraces. The strong interaction between the C60 molecules and the gold substrate is well screened by the DCP monolayer. At submonolayer C60 coverage, the fullerene molecules form long parallel chains, 1.1 nm apart, with a rectangular arrangement instead of the expected close-packed configuration along the upper step edges. The perfectly ordered DCP structure is unaffected by the C60 chain formation. The controlled sharp highly-ordered organic interface has the potential to improve the conversion efficiency in organic photovoltaics.

Conformation transitions of a single polyelectrolyte chain in a poor solvent: a replica-exchange lattice Monte-Carlo study.

PubMed

Wang, Lang; Wang, Zheng; Jiang, Run; Yin, Yuhua; Li, Baohui

2017-03-15

The thermodynamic behaviors of a strongly charged polyelectrolyte chain in a poor solvent are studied using replica-exchange Monte-Carlo simulations on a lattice model, focusing on the effects of finite chain length and the solvent quality on the chain conformation and conformation transitions. The neutralizing counterions and solvent molecules are considered explicitly. The thermodynamic quantities that vary continuously with temperature over a wide range are computed using the multiple histogram reweighting method. Our results suggest that the strength of the short-range hydrophobic interaction, the chain length, and the temperature of the system, characterized by ε, N, and T, respectively, are important parameters that control the conformations of a charged chain. When ε is moderate, the competition between the electrostatic energy and the short-range hydrophobic interaction leads to rich conformations and conformation transitions for a longer chain with a fixed length. Our results have unambiguously demonstrated the stability of the n-pearl-necklace structures, where n has a maximum value and decreases with decreasing temperature. The maximum n value increases with increasing chain length. Our results have also demonstrated the first-order nature of the conformation transitions between the m-pearl and the (m-1)-pearl necklaces. With the increase of ε, the transition temperature increases and the first-order feature becomes more pronounced. It is deduced that at the thermodynamic limit of infinitely long chain length, the conformational transitions between the m-pearl and the (m-1)-pearl necklaces may remain first order when ε > 0 and m = 2 or 3. Pearl-necklace conformations cannot be observed when either ε is too large or N is too small. To observe a pearl-necklace conformation, the T value needs to be carefully chosen for simulations performed at only a single temperature.

Image sensor with high dynamic range linear output

NASA Technical Reports Server (NTRS)

Yadid-Pecht, Orly (Inventor); Fossum, Eric R. (Inventor)

2007-01-01

Designs and operational methods to increase the dynamic range of image sensors and APS devices in particular by achieving more than one integration times for each pixel thereof. An APS system with more than one column-parallel signal chains for readout are described for maintaining a high frame rate in readout. Each active pixel is sampled for multiple times during a single frame readout, thus resulting in multiple integration times. The operation methods can also be used to obtain multiple integration times for each pixel with an APS design having a single column-parallel signal chain for readout. Furthermore, analog-to-digital conversion of high speed and high resolution can be implemented.

Exact analytical modeling of lightwave propagation in planar media with arbitrarily graded index profiles

NASA Astrophysics Data System (ADS)

Krapez, J.-C.

2018-02-01

Applying the Darboux transformation in the optical-depth space allows building infinite chains of exact analytical solutions of the electromagnetic (EM) fields in planar 1D-graded dielectrics. As a matter of fact, infinite chains of solvable admittance profiles (e.g. refractive-index profiles, in the case of non-magnetic materials), together with the related EM fields are simultaneously and recursively obtained. The whole procedure has received the name "PROFIDT method" for PROperty and FIeld Darboux Transformation method. By repeating the Darboux transformations we can find out progressively more complex profiles and their EM solutions. An alternative is to stop after the first step and settle for a particular class of four-parameter admittance profiles that were dubbed of "sech(ξ)-type". These profiles are highly flexible. For this reason, they can be used as elementary bricks for building and modeling profiles of arbitrary shape. In addition, the corresponding transfer matrix involves only elementary functions. The sub-class of "sech(ξ)-type" profiles with horizontal end-slopes (S-shaped function) is particularly interesting: these can be used for high-level modeling of piecewise-sigmoidal refractive-index profiles encountered in various photonic devices such as matchinglayers, antireflection layers, rugate filters, chirped mirrors and photonic crystals. These simple analytical tools also allow exploring the fascinating properties of a new kind of structure, namely smooth quasicrystals. They can also be applied to model propagation of other types of waves in graded media such as acoustic waves and electric waves in tapered transmission lines.

Marginally specified priors for non-parametric Bayesian estimation

PubMed Central

Kessler, David C.; Hoff, Peter D.; Dunson, David B.

2014-01-01

Summary Prior specification for non-parametric Bayesian inference involves the difficult task of quantifying prior knowledge about a parameter of high, often infinite, dimension. A statistician is unlikely to have informed opinions about all aspects of such a parameter but will have real information about functionals of the parameter, such as the population mean or variance. The paper proposes a new framework for non-parametric Bayes inference in which the prior distribution for a possibly infinite dimensional parameter is decomposed into two parts: an informative prior on a finite set of functionals, and a non-parametric conditional prior for the parameter given the functionals. Such priors can be easily constructed from standard non-parametric prior distributions in common use and inherit the large support of the standard priors on which they are based. Additionally, posterior approximations under these informative priors can generally be made via minor adjustments to existing Markov chain approximation algorithms for standard non-parametric prior distributions. We illustrate the use of such priors in the context of multivariate density estimation using Dirichlet process mixture models, and in the modelling of high dimensional sparse contingency tables. PMID:25663813

MD simulation study of the diffusion and local structure of n-alkanes in liquid and supercritical methanol at infinite dilution.

PubMed

Feng, Huajie; Gao, Wei; Su, Li; Sun, Zhenfan; Chen, Liuping

2017-06-01

The diffusion coefficients of 14 n-alkanes (ranging from methane to n-tetradecane) in liquid and supercritical methanol at infinite dilution (at a pressure of 10.5 MPa and at temperatures of 299 K and 515 K) were deduced via molecular dynamics simulations. Values for the radial distribution function, coordination number, and number of hydrogen bonds were then calculated to explore the local structure of each fluid. The flexibility of the n-alkane (as characterized by the computed dihedral distribution, end-to-end distance, and radius of gyration) was found to be a major influence and hydrogen bonding to be a minor influence on the local structure. Hydrogen bonding reduces the flexibility of the n-alkane, whereas increasing the temperature enhances its flexibility, with temperature having a greater effect than hydrogen bonding on flexibility. Graphical abstract The flexibility of the alkane is a major influence and the hydrogen bonding is a minor influence on the first solvation shell; the coordination numbers of long-chain n-alkanes in the first solvation shell are rather low.

Improved numerical methods for infinite spin chains with long-range interactions

NASA Astrophysics Data System (ADS)

Nebendahl, V.; Dür, W.

2013-02-01

We present several improvements of the infinite matrix product state (iMPS) algorithm for finding ground states of one-dimensional quantum systems with long-range interactions. As a main ingredient, we introduce the superposed multioptimization method, which allows an efficient optimization of exponentially many MPS of different lengths at different sites all in one step. Here, the algorithm becomes protected against position-dependent effects as caused by spontaneously broken translational invariance. So far, these have been a major obstacle to convergence for the iMPS algorithm if no prior knowledge of the system's translational symmetry was accessible. Further, we investigate some more general methods to speed up calculations and improve convergence, which might be partially interesting in a much broader context, too. As a more special problem, we also look into translational invariant states close to an invariance-breaking phase transition and show how to avoid convergence into wrong local minima for such systems. Finally, we apply these methods to polar bosons with long-range interactions. We calculate several detailed Devil's staircases with the corresponding phase diagrams and investigate some supersolid properties.

Current reversals and metastable states in the infinite Bose-Hubbard chain with local particle loss

NASA Astrophysics Data System (ADS)

Kiefer-Emmanouilidis, M.; Sirker, J.

2017-12-01

We present an algorithm which combines the quantum trajectory approach to open quantum systems with a density-matrix renormalization-group scheme for infinite one-dimensional lattice systems. We apply this method to investigate the long-time dynamics in the Bose-Hubbard model with local particle loss starting from a Mott-insulating initial state with one boson per site. While the short-time dynamics can be described even quantitatively by an equation of motion (EOM) approach at the mean-field level, many-body interactions lead to unexpected effects at intermediate and long times: local particle currents far away from the dissipative site start to reverse direction ultimately leading to a metastable state with a total particle current pointing away from the lossy site. An alternative EOM approach based on an effective fermion model shows that the reversal of currents can be understood qualitatively by the creation of holon-doublon pairs at the edge of the region of reduced particle density. The doublons are then able to escape while the holes move towards the dissipative site, a process reminiscent—in a loose sense—of Hawking radiation.

Low-temperature transport in out-of-equilibrium XXZ chains

NASA Astrophysics Data System (ADS)

Bertini, Bruno; Piroli, Lorenzo

2018-03-01

We study the low-temperature transport properties of out-of-equilibrium XXZ spin-1/2 chains. We consider the protocol where two semi-infinite chains are prepared in two thermal states at small but different temperatures and suddenly joined together. We focus on the qualitative and quantitative features of the profiles of local observables, which at large times t and distances x from the junction become functions of the ratio \\zeta=x/t . By means of the generalized hydrodynamic equations, we analyse the rich phenomenology arising by considering different regimes of the phase diagram. In the gapped phases, variations of the profiles are found to be exponentially small in the temperatures, but described by non-trivial functions of ζ. We provide analytical formulae for the latter, which give accurate results also for small but finite temperatures. In the gapless regime, we show how the three-step conformal predictions for the profiles of energy density and energy current are naturally recovered from the hydrodynamic equations. Moreover, we also recover the recent non-linear Luttinger liquid predictions for low-temperature transport: universal peaks of width \

The Role of Instability Waves in Predicting Jet Noise

NASA Technical Reports Server (NTRS)

Goldstein, M. E.; Leib, S. J.

2004-01-01

There has been an ongoing debate about the role of linear instability waves in the prediction of jet noise. Parallel mean flow models, such as the one proposed by Lilley, usually neglect these waves because they cause the solution to become infinite. The resulting solution is then non-causal and can, therefore, be quite different from the true causal solution for the chaotic flows being considered here. The present paper solves the relevant acoustic equations for a non-parallel mean flow by using a vector Green s function approach and assuming the mean flow to be weakly non-parallel, i.e., assuming the spread rate to be small. It demonstrates that linear instability waves must be accounted for in order to construct a proper causal solution to the jet noise problem. . Recent experimental results (e.g., see Tam, Golebiowski, and Seiner,1996) show that the small angle spectra radiated by supersonic jets are quite different from those radiated at larger angles (say, at 90deg) and even exhibit dissimilar frequency scalings (i.e., they scale with Helmholtz number as opposed to Strouhal number). The present solution is (among other things )able to explain this rather puzzling experimental result.

CudaChain: an alternative algorithm for finding 2D convex hulls on the GPU.

PubMed

Mei, Gang

2016-01-01

This paper presents an alternative GPU-accelerated convex hull algorithm and a novel S orting-based P reprocessing A pproach (SPA) for planar point sets. The proposed convex hull algorithm termed as CudaChain consists of two stages: (1) two rounds of preprocessing performed on the GPU and (2) the finalization of calculating the expected convex hull on the CPU. Those interior points locating inside a quadrilateral formed by four extreme points are first discarded, and then the remaining points are distributed into several (typically four) sub regions. For each subset of points, they are first sorted in parallel; then the second round of discarding is performed using SPA; and finally a simple chain is formed for the current remaining points. A simple polygon can be easily generated by directly connecting all the chains in sub regions. The expected convex hull of the input points can be finally obtained by calculating the convex hull of the simple polygon. The library Thrust is utilized to realize the parallel sorting, reduction, and partitioning for better efficiency and simplicity. Experimental results show that: (1) SPA can very effectively detect and discard the interior points; and (2) CudaChain achieves 5×-6× speedups over the famous Qhull implementation for 20M points.

The Acquisition of Pronouns by French Children: A Parallel Study of Production and Comprehension

ERIC Educational Resources Information Center

Zesiger, Pascal; Zesiger, Laurence Chillier; Arabatzi, Marina; Baranzini, Lara; Cronel-Ohayon, Stephany; Franck, Julie; Frauenfelder, Ulrich Hans; Hamann, Cornelia; Rizzi, Luigi

2010-01-01

This study examines syntactic and morphological aspects of the production and comprehension of pronouns by 99 typically developing French-speaking children aged 3 years, 5 months to 6 years, 5 months. A fine structural analysis of subject, object, and reflexive clitics suggests that whereas the object clitic chain crosses the subject chain, the…

Renormalized charge in a two-dimensional model of colloidal suspension from hypernetted chain approach.

PubMed

Camargo, Manuel; Téllez, Gabriel

2008-04-07

The renormalized charge of a simple two-dimensional model of colloidal suspension was determined by solving the hypernetted chain approximation and Ornstein-Zernike equations. At the infinite dilution limit, the asymptotic behavior of the correlation functions is used to define the effective interactions between the components of the system and these effective interactions were compared to those derived from the Poisson-Boltzmann theory. The results we obtained show that, in contrast to the mean-field theory, the renormalized charge does not saturate, but exhibits a maximum value and then decays monotonically as the bare charge increases. The results also suggest that beyond the counterion layer near to the macroion surface, the ionic cloud is not a diffuse layer which can be handled by means of the linearized theory, as the two-state model claims, but a more complex structure is settled by the correlations between microions.

Crystal structure and luminescence properties of silver in AgM(PO{sub 3}){sub 3} (M = Mg, Zn, Ba) polyphosphates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belharouak, I.; Parent, C.; Tanguy, B.

1999-06-01

The relationships between the crystal structures and the luminescent properties of the AgM(PO{sub 3}){sub 3} (M = Mg, Zn, Ba) polyphosphates are reported in comparison with those of AgPO{sub 3}. The structure of the magnesium and zinc phosphates is characterized by long polyphosphates chains connected to infinite chains of [AgO{sub 6}] and [MO{sub 6}] polyhedra sharing faces. The basic structural phosphate unit in AgBa(PO{sub 3}){sub 3} is a P{sub 3}O{sub 9} ring. Silver atoms are located in distorted octahedral sites. Two types of luminescent centers have been observed. The UV emission observed in all these materials is typical of isolatedmore » Ag{sup +} ions. The visible emission observed only in the zinc phosphate is probably the result of a silver-zinc association. 16 refs., 8 figs., 3 tabs.« less

Finite-temperature dynamic structure factor of the spin-1 XXZ chain with single-ion anisotropy

NASA Astrophysics Data System (ADS)

Lange, Florian; Ejima, Satoshi; Fehske, Holger

2018-02-01

Improving matrix-product state techniques based on the purification of the density matrix, we are able to accurately calculate the finite-temperature dynamic response of the infinite spin-1 XXZ chain with single-ion anisotropy in the Haldane, large-D , and antiferromagnetic phases. Distinct thermally activated scattering processes make a significant contribution to the spectral weight in all cases. In the Haldane phase, intraband magnon scattering is prominent, and the on-site anisotropy causes the magnon to split into singlet and doublet branches. In the large-D phase response, the intraband signal is separated from an exciton-antiexciton continuum. In the antiferromagnetic phase, holons are the lowest-lying excitations, with a gap that closes at the transition to the Haldane state. At finite temperatures, scattering between domain-wall excitations becomes especially important and strongly enhances the spectral weight for momentum transfer π .

dl-Asparaginium nitrate

PubMed Central

Moussa Slimane, Nabila; Cherouana, Aouatef; Bendjeddou, Lamia; Dahaoui, Slimane; Lecomte, Claude

2009-01-01

In the title compound, C4H9N2O3 +·NO3 −, alternatively called (1RS)-2-carbamoyl-1-carboxy­ethanaminium nitrate, the asymmetric unit comprises one asparaginium cation and one nitrate anion. The strongest cation–cation O—H⋯O hydrogen bond in the structure, together with other strong cation–cation N—H⋯O hydrogen bonds, generates a succession of infinite chains of R 2 2(8) rings along the b axis. Additional cation–cation C—H⋯O hydrogen bonds link these chains into two-dimensional layers formed by alternating R 4 4(24) and R 4 2(12) rings. Connections between these layers are provided by the strong cation–anion N—H⋯O hydrogen bonds, as well as by one weak C—H⋯O inter­action, thus forming a three-dimensional network. Some of the cation–anion N—H⋯O hydrogen bonds are bifurcated of the type D—H⋯(A 1,A 2). PMID:21577586

Continuous higher-order sliding mode control with time-varying gain for a class of uncertain nonlinear systems.

PubMed

Han, Yaozhen; Liu, Xiangjie

2016-05-01

This paper presents a continuous higher-order sliding mode (HOSM) control scheme with time-varying gain for a class of uncertain nonlinear systems. The proposed controller is derived from the concept of geometric homogeneity and super-twisting algorithm, and includes two parts, the first part of which achieves smooth finite time stabilization of pure integrator chains. The second part conquers the twice differentiable uncertainty and realizes system robustness by employing super-twisting algorithm. Particularly, time-varying switching control gain is constructed to reduce the switching control action magnitude to the minimum possible value while keeping the property of finite time convergence. Examples concerning the perturbed triple integrator chains and excitation control for single-machine infinite bus power system are simulated respectively to demonstrate the effectiveness and applicability of the proposed approach. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Generalized thermalization for integrable system under quantum quench.

PubMed

Muralidharan, Sushruth; Lochan, Kinjalk; Shankaranarayanan, S

2018-01-01

We investigate equilibration and generalized thermalization of the quantum Harmonic chain under local quantum quench. The quench action we consider is connecting two disjoint harmonic chains of different sizes and the system jumps between two integrable settings. We verify the validity of the generalized Gibbs ensemble description for this infinite-dimensional Hilbert space system and also identify equilibration between the subsystems as in classical systems. Using Bogoliubov transformations, we show that the eigenstates of the system prior to the quench evolve toward the Gibbs Generalized Ensemble description. Eigenstates that are more delocalized (in the sense of inverse participation ratio) prior to the quench, tend to equilibrate more rapidly. Further, through the phase space properties of a generalized Gibbs ensemble and the strength of stimulated emission, we identify the necessary criterion on the initial states for such relaxation at late times and also find out the states that would potentially not be described by the generalized Gibbs ensemble description.

Synthesis, structure, and magnetic properties of two 1-D helical coordination polymeric Cu(II) complexes

NASA Astrophysics Data System (ADS)

Bian, He-Dong; Yang, Xiao-E.; Yu, Qing; Chen, Zi-Lu; Liang, Hong; Yan, Shi-Ping; Liao, Dai-Zheng

2008-01-01

Two helical coordination polymeric copper(II) complexes bearing amino acid Schiff bases HL or HL', which are condensed from 2-hydroxy-1-naphthaldehyde with 2-aminobenzoic acid or L-valine, respectively, have been prepared and characterised by X-ray crystallography. In [CuL] n ( 1) the copper(II) atoms are bridged by syn- anti carboxylate groups giving infinite 1-D right-handed helical chains which are further connected by weak C-H⋯Cu interactions to build a 2-D network. While in [CuL'] n ( 2) the carboxylate group acts as a rare monatomic bridge to connect the adjacent copper(II) atoms leading to the formation of a left-handed helical chain. Magnetic susceptibility measurements indicate that 1 exhibits weak ferromagnetic interactions whereas an antiferromagnetic coupling is established for 2. The magnetic behavior can be satisfactorily explained on the basis of the structural data.

Spin-filtering and giant magnetoresistance effects in polyacetylene-based molecular devices

NASA Astrophysics Data System (ADS)

Chen, Tong; Yan, Shenlang; Xu, Liang; Liu, Desheng; Li, Quan; Wang, Lingling; Long, Mengqiu

2017-07-01

Using the non-equilibrium Green's function formalism in combination with density functional theory, we performed ab initio calculations of spin-dependent electron transport in molecular devices consisting of a polyacetylene (CnHn+1) chain vertically attached to a carbon chain sandwiched between two semi-infinite zigzag-edged graphene nanoribbon electrodes. Spin-charge transport in the device could be modulated to different magnetic configurations by an external magnetic field. The results showed that single spin conduction could be obtained. Specifically, the proposed CnHn+1 devices exhibited several interesting effects, including (dual) spin filtering, spin negative differential resistance, odd-even oscillation, and magnetoresistance (MR). Marked spin polarization with a filtering efficiency of up to 100% over a large bias range was found, and the highest MR ratio for the CnHn+1 junctions reached 4.6 × 104. In addition, the physical mechanisms for these phenomena were also revealed.

A two-dimensional ZnII coordination polymer constructed from benzene-1,2,3-tricarboxylic acid and N,N'-bis[(pyridin-4-yl)methylidene]hydrazine.

PubMed

Wang, Xiangfei; Yang, Fang; Tang, Meng; Yuan, Limin; Liu, Wenlong

2015-07-01

The hydrothermal synthesis of the novel complex poly[aqua(μ4-benzene-1,2,3-tricarboxylato)[μ2-4,4'-(hydrazine-1,2-diylidenedimethanylylidene)dipyridine](μ3-hydroxido)dizinc(II)], [Zn(C9H3O6)(OH)(C12H10N4)(H2O)]n, is described. The benzene-1,2,3-tricarboxylate ligand connects neighbouring Zn4(OH)2 secondary building units (SBUs) producing an infinite one-dimensional chain. Adjacent one-dimensional chains are connected by the N,N'-bis[(pyridin-4-yl)methylidene]hydrazine ligand, forming a two-dimensional layered structure. Adjacent layers are stacked to generate a three-dimensional supramolecular architecture via O-H...O hydrogen-bond interactions. The thermal stability of this complex is described and the complex also appears to have potential for application as a luminescent material.

A menu-driven software package of Bayesian nonparametric (and parametric) mixed models for regression analysis and density estimation.

PubMed

Karabatsos, George

2017-02-01

Most of applied statistics involves regression analysis of data. In practice, it is important to specify a regression model that has minimal assumptions which are not violated by data, to ensure that statistical inferences from the model are informative and not misleading. This paper presents a stand-alone and menu-driven software package, Bayesian Regression: Nonparametric and Parametric Models, constructed from MATLAB Compiler. Currently, this package gives the user a choice from 83 Bayesian models for data analysis. They include 47 Bayesian nonparametric (BNP) infinite-mixture regression models; 5 BNP infinite-mixture models for density estimation; and 31 normal random effects models (HLMs), including normal linear models. Each of the 78 regression models handles either a continuous, binary, or ordinal dependent variable, and can handle multi-level (grouped) data. All 83 Bayesian models can handle the analysis of weighted observations (e.g., for meta-analysis), and the analysis of left-censored, right-censored, and/or interval-censored data. Each BNP infinite-mixture model has a mixture distribution assigned one of various BNP prior distributions, including priors defined by either the Dirichlet process, Pitman-Yor process (including the normalized stable process), beta (two-parameter) process, normalized inverse-Gaussian process, geometric weights prior, dependent Dirichlet process, or the dependent infinite-probits prior. The software user can mouse-click to select a Bayesian model and perform data analysis via Markov chain Monte Carlo (MCMC) sampling. After the sampling completes, the software automatically opens text output that reports MCMC-based estimates of the model's posterior distribution and model predictive fit to the data. Additional text and/or graphical output can be generated by mouse-clicking other menu options. This includes output of MCMC convergence analyses, and estimates of the model's posterior predictive distribution, for selected functionals and values of covariates. The software is illustrated through the BNP regression analysis of real data.

Template-directed atomically precise self-organization of perfectly ordered parallel cerium silicide nanowire arrays on Si(110)-16 × 2 surfaces.

PubMed

Hong, Ie-Hong; Liao, Yung-Cheng; Tsai, Yung-Feng

2013-11-05

The perfectly ordered parallel arrays of periodic Ce silicide nanowires can self-organize with atomic precision on single-domain Si(110)-16 × 2 surfaces. The growth evolution of self-ordered parallel Ce silicide nanowire arrays is investigated over a broad range of Ce coverages on single-domain Si(110)-16 × 2 surfaces by scanning tunneling microscopy (STM). Three different types of well-ordered parallel arrays, consisting of uniformly spaced and atomically identical Ce silicide nanowires, are self-organized through the heteroepitaxial growth of Ce silicides on a long-range grating-like 16 × 2 reconstruction at the deposition of various Ce coverages. Each atomically precise Ce silicide nanowire consists of a bundle of chains and rows with different atomic structures. The atomic-resolution dual-polarity STM images reveal that the interchain coupling leads to the formation of the registry-aligned chain bundles within individual Ce silicide nanowire. The nanowire width and the interchain coupling can be adjusted systematically by varying the Ce coverage on a Si(110) surface. This natural template-directed self-organization of perfectly regular parallel nanowire arrays allows for the precise control of the feature size and positions within ±0.2 nm over a large area. Thus, it is a promising route to produce parallel nanowire arrays in a straightforward, low-cost, high-throughput process.

Template-directed atomically precise self-organization of perfectly ordered parallel cerium silicide nanowire arrays on Si(110)-16 × 2 surfaces

PubMed Central

2013-01-01

The perfectly ordered parallel arrays of periodic Ce silicide nanowires can self-organize with atomic precision on single-domain Si(110)-16 × 2 surfaces. The growth evolution of self-ordered parallel Ce silicide nanowire arrays is investigated over a broad range of Ce coverages on single-domain Si(110)-16 × 2 surfaces by scanning tunneling microscopy (STM). Three different types of well-ordered parallel arrays, consisting of uniformly spaced and atomically identical Ce silicide nanowires, are self-organized through the heteroepitaxial growth of Ce silicides on a long-range grating-like 16 × 2 reconstruction at the deposition of various Ce coverages. Each atomically precise Ce silicide nanowire consists of a bundle of chains and rows with different atomic structures. The atomic-resolution dual-polarity STM images reveal that the interchain coupling leads to the formation of the registry-aligned chain bundles within individual Ce silicide nanowire. The nanowire width and the interchain coupling can be adjusted systematically by varying the Ce coverage on a Si(110) surface. This natural template-directed self-organization of perfectly regular parallel nanowire arrays allows for the precise control of the feature size and positions within ±0.2 nm over a large area. Thus, it is a promising route to produce parallel nanowire arrays in a straightforward, low-cost, high-throughput process. PMID:24188092

The effect of electrodes on 11 acene molecular spin valve: Semi-empirical study

NASA Astrophysics Data System (ADS)

Aadhityan, A.; Preferencial Kala, C.; John Thiruvadigal, D.

2017-10-01

A new revolution in electronics is molecular spintronics, with the contemporary evolution of the two novel disciplines of spintronics and molecular electronics. The key point is the creation of molecular spin valve which consists of a diamagnetic molecule in between two magnetic leads. In this paper, non-equilibrium Green's function (NEGF) combined with Extended Huckel Theory (EHT); a semi-empirical approach is used to analyse the electron transport characteristics of 11 acene molecular spin valve. We examine the spin-dependence transport on 11 acene molecular junction with various semi-infinite electrodes as Iron, Cobalt and Nickel. To analyse the spin-dependence transport properties the left and right electrodes are joined to the central region in parallel and anti-parallel configurations. We computed spin polarised device density of states, projected device density of states of carbon and the electrode element, and transmission of these devices. The results demonstrate that the effect of electrodes modifying the spin-dependence behaviours of these systems in a controlled way. In Parallel and anti-parallel configuration the separation of spin up and spin down is lager in the case of iron electrode than nickel and cobalt electrodes. It shows that iron is the best electrode for 11 acene spin valve device. Our theoretical results are reasonably impressive and trigger our motivation for comprehending the transport properties of these molecular-sized contacts.

General polytropic self-gravitating cylinder free-fall and accreting mass string with a chain of collapsed objects

NASA Astrophysics Data System (ADS)

Lou, Yu-Qing; Hu, Xu-Yao

2016-06-01

We present a theoretical model framework for general polytropic (GP) hydrodynamic cylinder under self-gravity of infinite length with axial uniformity and axisymmetry. For self-similar dynamic solutions, we derive valuable integrals, analytic asymptotic solutions, sonic critical curves, shock conditions, and global numerical solutions with or without expansion shocks. Among others, we investigate various dynamic solutions featured with central free-fall asymptotic behaviours, corresponding to a collapsed mass string with a sustained dynamic accretion from a surrounding mass reservoir. Depending on the allowed ranges of a scaling index a < -1, such cylindrical dynamic mass accretion rate could be steady, increasing with time and decreasing with time. Physically, such a collapsed mass string or filament would break up into a sequence of sub-clumps and segments as induced by gravitational Jeans instabilities. Depending on the scales involved, such sub-clumps would evolve into collapsed objects or gravitationally bound systems. In diverse astrophysical and cosmological contexts, such a scenario can be adapted on various temporal, spatial and mass scales to form a chain of collapsed clumps and/or compact objects. Examples include the formation of chains of proto-stars, brown dwarfs and gaseous planets along molecular filaments; the formation of luminous massive stars along magnetized spiral arms and circum-nuclear starburst rings in barred spiral galaxies; the formation of chains of compact stellar objects such as white dwarfs, neutron stars, and black holes along a highly condensed mass string. On cosmological scales, one can perceive the formation of chains of galaxies, chains of galaxy clusters or even chains of supermassive and hypermassive black holes in the Universe including the early Universe. All these chains referred to above include possible binaries.

Quantum quenches in two spatial dimensions using chain array matrix product states

DOE PAGES

A. J. A. James; Konik, R.

2015-10-15

We describe a method for simulating the real time evolution of extended quantum systems in two dimensions (2D). The method combines the benefits of integrability and matrix product states in one dimension to avoid several issues that hinder other applications of tensor based methods in 2D. In particular, it can be extended to infinitely long cylinders. As an example application we present results for quantum quenches in the 2D quantum [(2+1)-dimensional] Ising model. As a result, in quenches that cross a phase boundary we find that the return probability shows nonanalyticities in time.

Crystal structure of 1,3-bis-(1H-benzotriazol-1-yl-meth-yl)benzene.

PubMed

Macías, Mario A; Nuñez-Dallos, Nelson; Hurtado, John; Suescun, Leopoldo

2016-06-01

The mol-ecular structure of the title compound, C20H16N6, contains two benzotriazole units bonded to a benzene nucleus in a meta configuration, forming dihedral angles of 88.74 (11) and 85.83 (10)° with the central aromatic ring and 57.08 (9)° with each other. The three-dimensional structure is controlled mainly by weak C-H⋯N and C-H⋯π inter-actions. The mol-ecules are connected in inversion-related pairs, forming the slabs of infinite chains that run along the [-110] and [110] directions.

Computer simulations of polymer chain structure and dynamics on a hypersphere in four-space

NASA Astrophysics Data System (ADS)

Râsmark, Per Johan; Ekholm, Tobias; Elvingson, Christer

2005-05-01

There is a rapidly growing interest in performing computer simulations in a closed space, avoiding periodic boundary conditions. To extend the range of potential systems to include also macromolecules, we describe an algorithm for computer simulations of polymer chain molecules on S3, a hypersphere in four dimensions. In particular, we show how to generate initial conformations with a bond angle distribution given by the persistence length of the chain and how to calculate the bending forces for a molecule moving on S3. Furthermore, we discuss how to describe the shape of a macromolecule on S3, by deriving the radius of gyration tensor in this non-Euclidean space. The results from both Monte Carlo and Brownian dynamics simulations in the infinite dilution limit show that the results on S3 and in R3 coincide, both with respect to the size and shape as well as for the diffusion coefficient. All data on S3 can also be described by master curves by suitable scaling by the corresponding values in R3. We thus show how to extend the use of spherical boundary conditions, which are most effective for calculating electrostatic forces, to polymer chain molecules, making it possible to perform simulations on S3 also for polyelectrolyte systems.

Crystal structure of catena-poly[N,N,N′,N′-tetra­methyl­guanidinium [(chlorido­cadmate)-di-μ-chlorido

PubMed Central

Ndiaye, Mamadou; Samb, Abdoulaye; Diop, Libasse; Maris, Thierry

2016-01-01

In the structure of the title salt, {(C5H14N3)[CdCl3]}n, the CdII atom of the complex anion is five-coordinated by one terminal and four bridging Cl atoms. The corresponding coordination polyhedron is a distorted trigonal bipyramid, with Cd—Cl distances in the range 2.4829 (4)–2.6402 (4) Å. The bipyramids are condensed into a polyanionic zigzag chain extending parallel to [101]. The tetra­methyl­guanidinium cations are situated between the polyanionic chains and are linked to them through N—H⋯Cl hydrogen bonds, forming a layered network parallel to (010). PMID:26870572

Resolution of Infinite-Loop in Hyperincursive and Nonlocal Cellular Automata: Introduction to Slime Mold Computing

NASA Astrophysics Data System (ADS)

Aono, Masashi; Gunji, Yukio-Pegio

2004-08-01

How can non-algorithmic/non-deterministic computational syntax be computed? "The hyperincursive system" introduced by Dubois is an anticipatory system embracing the contradiction/uncertainty. Although it may provide a novel viewpoint for the understanding of complex systems, conventional digital computers cannot run faithfully as the hyperincursive computational syntax specifies, in a strict sense. Then is it an imaginary story? In this paper we try to argue that it is not. We show that a model of complex systems "Elementary Conflictable Cellular Automata (ECCA)" proposed by Aono and Gunji is embracing the hyperincursivity and the nonlocality. ECCA is based on locality-only type settings basically as well as other CA models, and/but at the same time, each cell is required to refer to globality-dominant regularity. Due to this contradictory locality-globality loop, the time evolution equation specifies that the system reaches the deadlock/infinite-loop. However, we show that there is a possibility of the resolution of these problems if the computing system has parallel and/but non-distributed property like an amoeboid organism. This paper is an introduction to "the slime mold computing" that is an attempt to cultivate an unconventional notion of computation.

Modelling of Rail Vehicles and Track for Calculation of Ground-Vibration Transmission Into Buildings

NASA Astrophysics Data System (ADS)

Hunt, H. E. M.

1996-05-01

A methodology for the calculation of vibration transmission from railways into buildings is presented. The method permits existing models of railway vehicles and track to be incorporated and it has application to any model of vibration transmission through the ground. Special attention is paid to the relative phasing between adjacent axle-force inputs to the rail, so that vibration transmission may be calculated as a random process. The vehicle-track model is used in conjunction with a building model of infinite length. The tracking and building are infinite and parallel to each other and forces applied are statistically stationary in space so that vibration levels at any two points along the building are the same. The methodology is two-dimensional for the purpose of application of random process theory, but fully three-dimensional for calculation of vibration transmission from the track and through the ground into the foundations of the building. The computational efficiency of the method will interest engineers faced with the task of reducing vibration levels in buildings. It is possible to assess the relative merits of using rail pads, under-sleeper pads, ballast mats, floating-slab track or base isolation for particular applications.

Re-radiation of acoustic waves from the A0 wave on a submerged elastic shell

NASA Astrophysics Data System (ADS)

Ahyi, A. C.; Cao, Hui; Raju, P. K.; Überall, Herbert

2005-07-01

We consider evacuated thin semi-infinite shells immersed in a fluid, which may be either of cylindrical shape with a hemispherical shell endcap, or formed two-dimensionally by semi-infinite parallel plates joined together by a semi-cylinder. The connected shell portions are joined in a manner to satisfy continuity but with a discontinuous radius of curvature. Acoustic waves are considered incident along the axis of symmetry (say the z axis) onto the curved portion of the shell, where they, at the critical angle of coincidence, generate Lamb and Stoneley-type waves in the shell. Computations were carried out using a code developed by Cao et al. [Chinese J. Acoust. 14, 317 (1995)] and was used in order to computationally visualize the waves in the fluid that have been re-radiated by the shell waves a the critical angle. The frequency range was below that of the lowest Lamb wave, and only the A0 wave (and partly the S0 wave) was observed to re-radiate into the fluid under our assumptions. The results will be compared to experimental results in which the re-radiated waves are optically visualized by the Schardin-Cranz schlieren method. .

Bolzano`s Approach to the Paradoxes of Infinity: Implications for Teaching

NASA Astrophysics Data System (ADS)

Waldegg, Guillermina

2005-08-01

In this paper we analyze excerpts of Paradoxes of the Infinite, the posthumous work of Bernard Bolzano (1781-1848), in order to show that Georg Cantor‘s (1845-1918) approach to the problem of defining actual mathematical infinity is not the most natural. In fact, Bolzano‘s approach to the paradoxes of infinity is more intuitive, while remaining internally coherent. Bolzano‘s approach, however, had limitations. We discuss implications for teaching, which include a better understanding of the responses of students to situations involving actual mathematical infinity, for it is possible to draw a kind of parallel between these responses and Bolzano‘s reasoning.

Linear stability of three-dimensional boundary layers - Effects of curvature and non-parallelism

NASA Technical Reports Server (NTRS)

Malik, M. R.; Balakumar, P.

1993-01-01

In this paper we study the effect of in-plane (wavefront) curvature on the stability of three-dimensional boundary layers. It is found that this effect is stabilizing or destabilizing depending upon the sign of the crossflow velocity profile. We also investigate the effects of surface curvature and nonparallelism on crossflow instability. Computations performed for an infinite-swept cylinder show that while convex curvature stabilizes the three-dimensional boundary layer, nonparallelism is, in general, destabilizing and the net effect of the two depends upon meanflow and disturbance parameters. It is also found that concave surface curvature further destabilizes the crossflow instability.

The effective propagation constants of SH wave in composites reinforced by dispersive parallel nanofibers

NASA Astrophysics Data System (ADS)

Qiang, FangWei; Wei, PeiJun; Li, Li

2012-07-01

In the present paper, the effective propagation constants of elastic SH waves in composites with randomly distributed parallel cylindrical nanofibers are studied. The surface stress effects are considered based on the surface elasticity theory and non-classical interfacial conditions between the nanofiber and the host are derived. The scattering waves from individual nanofibers embedded in an infinite elastic host are obtained by the plane wave expansion method. The scattering waves from all fibers are summed up to obtain the multiple scattering waves. The interactions among random dispersive nanofibers are taken into account by the effective field approximation. The effective propagation constants are obtained by the configurational average of the multiple scattering waves. The effective speed and attenuation of the averaged wave and the associated dynamical effective shear modulus of composites are numerically calculated. Based on the numerical results, the size effects of the nanofibers on the effective propagation constants and the effective modulus are discussed.

Development of structural schemes of parallel structure manipulators using screw calculus

NASA Astrophysics Data System (ADS)

Rashoyan, G. V.; Shalyukhin, K. A.; Gaponenko, EV

2018-03-01

The paper considers the approach to the structural analysis and synthesis of parallel structure robots based on the mathematical apparatus of groups of screws and on a concept of reciprocity of screws. The results are depicted of synthesis of parallel structure robots with different numbers of degrees of freedom, corresponding to the different groups of screws. Power screws are applied with this aim, based on the principle of static-kinematic analogy; the power screws are similar to the orts of axes of not driven kinematic pairs of a corresponding connecting chain. Accordingly, kinematic screws of the outlet chain of a robot are simultaneously determined which are reciprocal to power screws of kinematic sub-chains. Solution of certain synthesis problems is illustrated with practical applications. Closed groups of screws can have eight types. The three-membered groups of screws are of greatest significance, as well as four-membered screw groups [1] and six-membered screw groups. Three-membered screw groups correspond to progressively guiding mechanisms, to spherical mechanisms, and to planar mechanisms. The four-membered group corresponds to the motion of the SCARA robot. The six-membered group includes all possible motions. From the works of A.P. Kotelnikov, F.M. Dimentberg, it is known that closed fifth-order screw groups do not exist. The article presents examples of the mechanisms corresponding to the given groups.

Strong contributions from vertical triads to helix-partner preferences in parallel coiled coils.

PubMed

Steinkruger, Jay D; Bartlett, Gail J; Woolfson, Derek N; Gellman, Samuel H

2012-09-26

Pairing preferences in heterodimeric coiled coils are determined by complementarities among side chains that pack against one another at the helix-helix interface. However, relationships between dimer stability and interfacial residue identity are not fully understood. In the context of the "knobs-into-holes" (KIH) packing pattern, one can identify two classes of interactions between side chains from different helices: "lateral", in which a line connecting the adjacent side chains is perpendicular to the helix axes, and "vertical", in which the connecting line is parallel to the helix axes. We have previously analyzed vertical interactions in antiparallel coiled coils and found that one type of triad constellation (a'-a-a') exerts a strong effect on pairing preferences, while the other type of triad (d'-d-d') has relatively little impact on pairing tendencies. Here, we ask whether vertical interactions (d'-a-d') influence pairing in parallel coiled-coil dimers. Our results indicate that vertical interactions can exert a substantial impact on pairing specificity, and that the influence of the d'-a-d' triad depends on the lateral a' contact within the local KIH motif. Structure-informed bioinformatic analyses of protein sequences reveal trends consistent with the thermodynamic data derived from our experimental model system in suggesting that heterotriads involving Leu and Ile are preferred over homotriads involving Leu and Ile.

An Evaluation of Kernel Equating: Parallel Equating with Classical Methods in the SAT Subject Tests[TM] Program. Research Report. ETS RR-09-06

ERIC Educational Resources Information Center

Grant, Mary C.; Zhang, Lilly; Damiano, Michele

2009-01-01

This study investigated kernel equating methods by comparing these methods to operational equatings for two tests in the SAT Subject Tests[TM] program. GENASYS (ETS, 2007) was used for all equating methods and scaled score kernel equating results were compared to Tucker, Levine observed score, chained linear, and chained equipercentile equating…

Carotid chemoreceptors tune breathing via multipath routing: reticular chain and loop operations supported by parallel spike train correlations.

PubMed

Morris, Kendall F; Nuding, Sarah C; Segers, Lauren S; Iceman, Kimberly E; O'Connor, Russell; Dean, Jay B; Ott, Mackenzie M; Alencar, Pierina A; Shuman, Dale; Horton, Kofi-Kermit; Taylor-Clark, Thomas E; Bolser, Donald C; Lindsey, Bruce G

2018-02-01

We tested the hypothesis that carotid chemoreceptors tune breathing through parallel circuit paths that target distinct elements of an inspiratory neuron chain in the ventral respiratory column (VRC). Microelectrode arrays were used to monitor neuronal spike trains simultaneously in the VRC, peri-nucleus tractus solitarius (p-NTS)-medial medulla, the dorsal parafacial region of the lateral tegmental field (FTL-pF), and medullary raphe nuclei together with phrenic nerve activity during selective stimulation of carotid chemoreceptors or transient hypoxia in 19 decerebrate, neuromuscularly blocked, and artificially ventilated cats. Of 994 neurons tested, 56% had a significant change in firing rate. A total of 33,422 cell pairs were evaluated for signs of functional interaction; 63% of chemoresponsive neurons were elements of at least one pair with correlational signatures indicative of paucisynaptic relationships. We detected evidence for postinspiratory neuron inhibition of rostral VRC I-Driver (pre-Bötzinger) neurons, an interaction predicted to modulate breathing frequency, and for reciprocal excitation between chemoresponsive p-NTS neurons and more downstream VRC inspiratory neurons for control of breathing depth. Chemoresponsive pericolumnar tonic expiratory neurons, proposed to amplify inspiratory drive by disinhibition, were correlationally linked to afferent and efferent "chains" of chemoresponsive neurons extending to all monitored regions. The chains included coordinated clusters of chemoresponsive FTL-pF neurons with functional links to widespread medullary sites involved in the control of breathing. The results support long-standing concepts on brain stem network architecture and a circuit model for peripheral chemoreceptor modulation of breathing with multiple circuit loops and chains tuned by tegmental field neurons with quasi-periodic discharge patterns. NEW & NOTEWORTHY We tested the long-standing hypothesis that carotid chemoreceptors tune the frequency and depth of breathing through parallel circuit operations targeting the ventral respiratory column. Responses to stimulation of the chemoreceptors and identified functional connectivity support differential tuning of inspiratory neuron burst duration and firing rate and a model of brain stem network architecture incorporating tonic expiratory "hub" neurons regulated by convergent neuronal chains and loops through rostral lateral tegmental field neurons with quasi-periodic discharge patterns.

Molecular dynamics simulation study of solvent effects on conformation and dynamics of polyethylene oxide and polypropylene oxide chains in water and in common organic solvents.

PubMed

Hezaveh, Samira; Samanta, Susruta; Milano, Giuseppe; Roccatano, Danilo

2012-03-28

In this paper, the conformation and dynamics properties of polyethylene oxide (PEO) and polypropylene oxide (PPO) polymer chains at 298 K have been studied in the melt and at infinite dilution condition in water, methanol, chloroform, carbon tetrachloride, and n-heptane using molecular dynamics simulations. The calculated density of PEO melt with chain lengths of n = 2, 3, 4, 5 and, for PPO, n = 7 are in good agreement with the available experimental data. The conformational properties of PEO and PPO show an increasing gauche preference for the O-C-C-O dihedral in the following order water>methanol>chloroform>carbon tetrachloride = n-heptane. On the contrary, the preference for trans conformation has a maximum in carbon tetrachloride and n-heptane followed in the order by chloroform, methanol, and water. The PEO conformational preferences are in qualitative agreement with results of NMR studies. PEO chains formed different types of hydrogen bonds with polar solvent molecules. In particular, the occurrence of bifurcated hydrogen bonding in chloroform was also observed. Radii of gyration of PEO chains of length larger than n = 9 monomers showed a good agreement with light scattering data in water and in methanol. For the shorter chains the observed deviations are probably due to the enhanced hydrophobic effects caused by the terminal methyl groups. For PEO the fitting of end-to-end distance distributions with the semi-flexible chain model at 298 K provided persistence lengths of 0.375 and 0.387 nm in water and methanol, respectively. Finally, the radius of gyration of Pluronic P85 turned out to be 2.25 ± 0.4 nm at 293 K in water in agreement with experimental data.

Molecular dynamics simulation study of solvent effects on conformation and dynamics of polyethylene oxide and polypropylene oxide chains in water and in common organic solvents

NASA Astrophysics Data System (ADS)

Hezaveh, Samira; Samanta, Susruta; Milano, Giuseppe; Roccatano, Danilo

2012-03-01

In this paper, the conformation and dynamics properties of polyethylene oxide (PEO) and polypropylene oxide (PPO) polymer chains at 298 K have been studied in the melt and at infinite dilution condition in water, methanol, chloroform, carbon tetrachloride, and n-heptane using molecular dynamics simulations. The calculated density of PEO melt with chain lengths of n = 2, 3, 4, 5 and, for PPO, n = 7 are in good agreement with the available experimental data. The conformational properties of PEO and PPO show an increasing gauche preference for the O-C-C-O dihedral in the following order water>methanol>chloroform>carbon tetrachloride = n-heptane. On the contrary, the preference for trans conformation has a maximum in carbon tetrachloride and n-heptane followed in the order by chloroform, methanol, and water. The PEO conformational preferences are in qualitative agreement with results of NMR studies. PEO chains formed different types of hydrogen bonds with polar solvent molecules. In particular, the occurrence of bifurcated hydrogen bonding in chloroform was also observed. Radii of gyration of PEO chains of length larger than n = 9 monomers showed a good agreement with light scattering data in water and in methanol. For the shorter chains the observed deviations are probably due to the enhanced hydrophobic effects caused by the terminal methyl groups. For PEO the fitting of end-to-end distance distributions with the semi-flexible chain model at 298 K provided persistence lengths of 0.375 and 0.387 nm in water and methanol, respectively. Finally, the radius of gyration of Pluronic P85 turned out to be 2.25 ± 0.4 nm at 293 K in water in agreement with experimental data.

Mechanical desorption of a single chain: unusual aspects of phase coexistence at a first-order transition.

PubMed

Skvortsov, Alexander M; Klushin, Leonid I; Polotsky, Alexey A; Binder, Kurt

2012-03-01

The phase transition occurring when a single polymer chain adsorbed at a planar solid surface is mechanically desorbed is analyzed in two statistical ensembles. In the force ensemble, a constant force applied to the nongrafted end of the chain (that is grafted at its other end) is used as a given external control variable. In the z-ensemble, the displacement z of this nongrafted end from the surface is taken as the externally controlled variable. Basic thermodynamic parameters, such as the adsorption energy, exhibit a very different behavior as a function of these control parameters. In the thermodynamic limit of infinite chain length the desorption transition with the force as a control parameter clearly is discontinuous, while in the z-ensemble continuous variations are found. However, one should not be misled by a too-naive application of the Ehrenfest criterion to consider the transition as a continuous transition: rather, one traverses a two-phase coexistence region, where part of the chain is still adsorbed and the other part desorbed and stretched. Similarities with and differences from two-phase coexistence at vapor-liquid transitions are pointed out. The rounding of the singularities due to finite chain length is illustrated by exact calculations for the nonreversal random walk model on the simple cubic lattice. A new concept of local order parameter profiles for the description of the mechanical desorption of adsorbed polymers is suggested. This concept give evidence for both the existence of two-phase coexistence within single polymer chains for this transition and the anomalous character of this two-phase coexistence. Consequences for the proper interpretation of experiments performed in different ensembles are briefly mentioned.

A reinvestigation of the crystal structure of α-Pb 2BiVO 6

NASA Astrophysics Data System (ADS)

Labidi, O.; Wignacourt, J. P.; Roussel, P.; Drache, M.; Conflant, P.; Steinfink, H.

2004-08-01

A previously reported β phase for Pb 2BiVO 6 has been characterized as a stable phase, and the phase transitions α→ β and β→ δ were identified in the mother phase as well as in Pb 2BiV 1- xM xO 6- y solid solutions (M=Cr, Mn); the high temperature form δ-Pb 2BiVO 6 eventually decomposes at 480 °C to a mixture of PbBiVO 5 and Pb 4BiVO 8 before showing recombination at 650 °C. The related substituted compositions behave the same way. The crystal structure of α-Pb 2BiVO 6 (I) is monoclinic, P2 1/ n, a=7.717(3) Å, b=5.845(3) Å, c=29.081(8) Å, β=94.27(1)°, Z=8. Oxygen atoms are in tetrahedral interstices formed by four Bi and Pb atoms. These tetrahedra articulate by BiPb edge sharing in two dimensions parallel to the b axis to form infinite chains. Mixed O(V Bi Pb) 4 tetrahedra bridge the O(Bi Pb) 4 ribbons by edge sharing to complete the three-dimensional articulation of the structure. α-Pb 2BiV 1- xMn xO 6- y ( x=0.06) (II) is monoclinic, P2 1/ m, a=7.684(3) Å, b=5.822(3) Å, c=14.708(6) Å, β=100.92(1)°, Z=4. Tetrahedral units of O(2Bi 2Pb) are also present in (II). They form dimers O 2Bi 4Pb 4 by BiBi edge sharing. The dimers form a chain along the b axis by sharing BiPb edges. Two independent MO 4 tetrahedra (M=V, Mn) are present in which one has V/Mn mixed occupancy. Both tetrahedra show statistical disorder by rotation around a VO apex. The disordered tetrahedral oxygen atoms are part of the coordination sphere of Bi and Pb. The matrix {-1 0 0, 0 -1 0, 1 0 2} relates the structures and unit cells of [I], and [II].

2,2′-Dimethoxy-4,4′-[rel-(2R,3S)-2,3-di­methylbutane-1,4-diyl]diphenol

PubMed Central

Salinas-Salazar, Carmen L.; del Rayo Camacho-Corona, María; Bernès, Sylvain; Waksman de Torres, Noemi

2009-01-01

The title mol­ecule, C20H26O4, commonly known as meso-dihydro­guaiaretic acid, is a naturally occurring lignan extracted from Larrea tridentata and other plants. The mol­ecule has a noncrystallographic inversion center situated at the midpoint of the central C—C bond, generating the meso stereoisomer. The central C—C—C—C alkyl chain displays an all-trans conformation, allowing an almost parallel arrangement of the benzene rings, which make a dihedral angle of 5.0 (3)°. Both hydr­oxy groups form weak O—H⋯O—H chains of hydrogen bonds along [100]. The resulting supra­molecular structure is an undulating plane parallel to (010). PMID:21583141

Scaling up antiretroviral therapy in Uganda: using supply chain management to appraise health systems strengthening.

PubMed

Windisch, Ricarda; Waiswa, Peter; Neuhann, Florian; Scheibe, Florian; de Savigny, Don

2011-08-01

Strengthened national health systems are necessary for effective and sustained expansion of antiretroviral therapy (ART). ART and its supply chain management in Uganda are largely based on parallel and externally supported efforts. The question arises whether systems are being strengthened to sustain access to ART. This study applies systems thinking to assess supply chain management, the role of external support and whether investments create the needed synergies to strengthen health systems. This study uses the WHO health systems framework and examines the issues of governance, financing, information, human resources and service delivery in relation to supply chain management of medicines and the technologies. It looks at links and causal chains between supply chain management for ART and the national supply system for essential drugs. It combines data from the literature and key informant interviews with observations at health service delivery level in a study district. Current drug supply chain management in Uganda is characterized by parallel processes and information systems that result in poor quality and inefficiencies. Less than expected health system performance, stock outs and other shortages affect ART and primary care in general. Poor performance of supply chain management is amplified by weak conditions at all levels of the health system, including the areas of financing, governance, human resources and information. Governance issues include the lack to follow up initial policy intentions and a focus on narrow, short-term approaches. The opportunity and need to use ART investments for an essential supply chain management and strengthened health system has not been exploited. By applying a systems perspective this work indicates the seriousness of missing system prerequisites. The findings suggest that root causes and capacities across the system have to be addressed synergistically to enable systems that can match and accommodate investments in disease-specific interventions. The multiplicity and complexity of existing challenges require a long-term and systems perspective essentially in contrast to the current short term and program-specific nature of external assistance.

Parallelism in Manipulator Dynamics. Revision.

DTIC Science & Technology

1983-12-01

computing the motor torques required to drive a lower-pair kinematic chain (e.g., a typical manipulator arm in free motion, or a mechanical leg in the... computations , and presents two "mathematically exact" formulationsespecially suited to high-speed, highly parallel implementa- tions using special-purpose...YNAMICS by I(IIAR) IIAROLI) LATIROP .4ISTRACT This paper addresses the problem of efficiently computing the motor torques required to drive a lower-pair

Partitioning of electron flux between the respiratory chains of the yeast Candida parapsilosis: parallel working of the two chains.

PubMed

Guerin, M G; Camougrand, N M

1994-02-08

Partitioning of the electron flux between the classical and the alternative respiratory chains of the yeast Candida parapsilosis, was measured as a function of the oxidation rate and of the Q-pool redox poise. At low respiration rate, electrons from external NADH travelled preferentially through the alternative pathway as indicated by the antimycin A-insensitivity of electron flow. Inhibition of the alternative pathway by SHAM restored full antimycin A-sensitivity to the remaining electro flow. The dependence of the respiratory rate on the redox poise of the quinone pool was investigated when the electron flux was mediated either by the main respiratory chain (growth in the absence of antimycin A) or by the second respiratory chain (growth in the presence of antimycin A). In the former case, a linear relationship was found between these two parameters. In contrast, in the latter case, the relationship between Q-pool reduction level and electron flux was non-linear, but it could be resolved into two distinct curves. This second quinone is not reducible in the presence of antimycin A but only in the presence of high concentrations of myxothiazol or cyanide. Since two quinone species exist in C. parapsilosis, UQ9 and Qx (C33H54O4), we hypothesized that these two curves could correspond to the functioning of the second quinone engaged during the alternative pathway activity. Partitioning of electrons between both respiratory chains could occur upstream of complex III with the second chain functioning in parallel to the main one, and with the additional possibility of merging into the main one at the complex IV level.

Properties of one-dimensional anharmonic lattice solitons

NASA Astrophysics Data System (ADS)

Szeftel, Jacob; Laurent-Gengoux, Pascal; Ilisca, Ernest; Hebbache, Mohamed

2000-12-01

The existence of bell- and kink-shaped solitons moving at constant velocity while keeping a permanent profile is studied in infinite periodic monoatomic chains of arbitrary anharmonicity by taking advantage of the equation of motion being integrable with respect to solitons. A second-order, non-linear differential equation involving advanced and retarded terms must be solved, which is done by implementing a scheme based on the finite element and Newton's methods. If the potential has a harmonic limit, the asymptotic time-decay behaves exponentially and there is a dispersion relation between propagation velocity and decay time. Inversely if the potential has no harmonic limit, the asymptotic regime shows up either as a power-law or faster than exponential. Excellent agreement is achieved with Toda's model. Illustrative examples are also given for the Fermi-Pasta-Ulam and sine-Gordon potentials. Owing to integrability an effective one-body potential is worked out in each case. Lattice and continuum solitons differ markedly from one another as regards the amplitude versus propagation velocity relationship and the asymptotic time behavior. The relevance of the linear stability analysis when applied to solitons propagating in an infinite crystal is questioned. The reasons preventing solitons from arising in a diatomic lattice are discussed.

Implementation of a fully-balanced periodic tridiagonal solver on a parallel distributed memory architecture

NASA Technical Reports Server (NTRS)

Eidson, T. M.; Erlebacher, G.

1994-01-01

While parallel computers offer significant computational performance, it is generally necessary to evaluate several programming strategies. Two programming strategies for a fairly common problem - a periodic tridiagonal solver - are developed and evaluated. Simple model calculations as well as timing results are presented to evaluate the various strategies. The particular tridiagonal solver evaluated is used in many computational fluid dynamic simulation codes. The feature that makes this algorithm unique is that these simulation codes usually require simultaneous solutions for multiple right-hand-sides (RHS) of the system of equations. Each RHS solutions is independent and thus can be computed in parallel. Thus a Gaussian elimination type algorithm can be used in a parallel computation and the more complicated approaches such as cyclic reduction are not required. The two strategies are a transpose strategy and a distributed solver strategy. For the transpose strategy, the data is moved so that a subset of all the RHS problems is solved on each of the several processors. This usually requires significant data movement between processor memories across a network. The second strategy attempts to have the algorithm allow the data across processor boundaries in a chained manner. This usually requires significantly less data movement. An approach to accomplish this second strategy in a near-perfect load-balanced manner is developed. In addition, an algorithm will be shown to directly transform a sequential Gaussian elimination type algorithm into the parallel chained, load-balanced algorithm.

Drastic stabilization of parallel DNA hybridizations by a polylysine comb-type copolymer with hydrophilic graft chain.

PubMed

Miyoshi, Daisuke; Ueda, Yu-Mi; Shimada, Naohiko; Nakano, Shu-Ichi; Sugimoto, Naoki; Maruyama, Atsushi

2014-09-01

Electrostatic interactions play a major role in protein-DNA interactions. As a model system of a cationic protein, herein we focused on a comb-type copolymer of a polycation backbone and dextran side chains, poly(L-lysine)-graft-dextran (PLL-g-Dex), which has been reported to form soluble interpolyelectrolyte complexes with DNA strands. We investigated the effects of PLL-g-Dex on the conformation and thermodynamics of DNA oligonucleotides forming various secondary structures. Thermodynamic analysis of the DNA structures showed that the parallel conformations involved in both DNA duplexes and triplexes were significantly and specifically stabilized by PLL-g-Dex. On the basis of thermodynamic parameters, it was further possible to design DNA switches that undergo structural transition responding to PLL-g-Dex from an antiparallel duplex to a parallel triplex even with mismatches in the third strand hybridization. These results suggest that polycationic molecules are able to induce structural polymorphism of DNA oligonucleotides, because of the conformation-selective stabilization effects. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Room-temperature synthesis of two-dimensional ultrathin gold nanowire parallel array with tunable spacing.

PubMed

Morita, Clara; Tanuma, Hiromitsu; Kawai, Chika; Ito, Yuki; Imura, Yoshiro; Kawai, Takeshi

2013-02-05

A series of long-chain amidoamine derivatives with different alkyl chain lengths (CnAA where n is 12, 14, 16, or 18) were synthesized and studied with regard to their ability to form organogels and to act as soft templates for the production of Au nanomaterials. These compounds were found to self-assemble into lamellar structures and exhibited gelation ability in some apolar solvents. The gelation concentration, gel-sol phase transition temperature, and lattice spacing of the lamellar structures in organic solvent all varied on the basis of the alkyl chain length of the particular CnAA compound employed. The potential for these molecules to function as templates was evaluated through the synthesis of Au nanowires (NWs) in their organogels. Ultrathin Au NWs were obtained from all CnAA/toluene gel systems, each within an optimal temperature range. Interestingly, in the case of C12AA and C14AA, it was possible to fabricate ultrathin Au NWs at room temperature. In addition, two-dimensional parallel arrays of ultrathin Au NWs were self-assembled onto TEM copper grids as a result of the drying of dispersion solutions of these NWs. The use of CnAA compounds with differing alkyl chain lengths enabled precise tuning of the distance between the Au NWs in these arrays.

Crystal structure of 1,3-bis­(1H-benzotriazol-1-yl­meth­yl)benzene

PubMed Central

Macías, Mario A.; Nuñez-Dallos, Nelson; Hurtado, John; Suescun, Leopoldo

2016-01-01

The mol­ecular structure of the title compound, C20H16N6, contains two benzotriazole units bonded to a benzene nucleus in a meta configuration, forming dihedral angles of 88.74 (11) and 85.83 (10)° with the central aromatic ring and 57.08 (9)° with each other. The three-dimensional structure is controlled mainly by weak C—H⋯N and C—H⋯π inter­actions. The mol­ecules are connected in inversion-related pairs, forming the slabs of infinite chains that run along the [-110] and [110] directions. PMID:27308049

Dannie Heineman Prize for Mathematical Physics Prize Lecture: Correlation Functions in Integrable Models II: The Role of Quantum Affine Symmetry

NASA Astrophysics Data System (ADS)

Jimbo, Michio

2013-03-01

Since the beginning of 1980s, hidden infinite dimensional symmetries have emerged as the origin of integrability: first in soliton theory and then in conformal field theory. Quest for symmetries in quantum integrable models has led to the discovery of quantum groups. On one hand this opened up rapid mathematical developments in representation theory, combinatorics and other fields. On the other hand it has advanced understanding of correlation functions of lattice models, leading to multiple integral formulas in integrable spin chains. We shall review these developments which continue up to the present time.

Design of Particulate-Reinforced Composite Materials

PubMed Central

Muc, Aleksander; Barski, Marek

2018-01-01

A microstructure-based model is developed to study the effective anisotropic properties (magnetic, dielectric or thermal) of two-phase particle-filled composites. The Green’s function technique and the effective field method are used to theoretically derive the homogenized (averaged) properties for a representative volume element containing isolated inclusion and infinite, chain-structured particles. Those results are compared with the finite element approximations conducted for the assumed representative volume element. In addition, the Maxwell–Garnett model is retrieved as a special case when particle interactions are not considered. We also give some information on the optimal design of the effective anisotropic properties taking into account the shape of magnetic particles. PMID:29401678

N-(2-Chloro­eth­yl)morpholine-4-carbox­amide

PubMed Central

Ujam, Oguejiofo T.; Asegbeloyin, Jonnie N.; Nicholson, Brian K.; Ukoha, Pius O.; Ukwueze, Nkechi N.

2014-01-01

The title compound, C7H13ClN2O2, synthesized by the reaction of 2-chloro­ethyl iso­cyanate and morpholine, crystallizes with four molecules in the asymmetric unit, which have similar conformations and comprise two pairs each related by approximate non-crystallographic inversion centres. Two of them have a modest orientational disorder of the 2-chloro­ethyl fragments [occupancy ratio of 0.778 (4):0.222 (4)]. In the crystal, mol­ecules are linked by N—H⋯O=C hydrogen bonds, forming three crystallographically different kinds of infinite hydrogen-bonded chains extending along [001]. PMID:24826162

Design-Parameters Setup for Power-Split Dual-Regime IVT

NASA Astrophysics Data System (ADS)

Preda, Ion; Ciolan, Gheorghe; Covaciu, Dinu

2017-10-01

To analyze the working possibilities of power-split infinitely variable transmissions (IVTs) it is necessary to follow a systematic approach. The method proposed in this paper consists of generating a block diagram of the transmission and then, based on this diagram, to derive the kinematics and dynamics equations of the transmission. For an actual numerical case, the derived equations are used to find characteristic values of the transmission components (gear and chain drives, planetary units) necessary to calculate the speed ratios, the speeds, torques and powers acting on the shafts and coupling (control) elements, and even to estimate the overall efficiency of the transmission.

Optimizing the way kinematical feed chains with great distance between slides are chosen for CNC machine tools

NASA Astrophysics Data System (ADS)

Lucian, P.; Gheorghe, S.

2017-08-01

This paper presents a new method, based on FRISCO formula, for optimizing the choice of the best control system for kinematical feed chains with great distance between slides used in computer numerical controlled machine tools. Such machines are usually, but not limited to, used for machining large and complex parts (mostly in the aviation industry) or complex casting molds. For such machine tools the kinematic feed chains are arranged in a dual-parallel drive structure that allows the mobile element to be moved by the two kinematical branches and their related control systems. Such an arrangement allows for high speed and high rigidity (a critical requirement for precision machining) during the machining process. A significant issue for such an arrangement it’s the ability of the two parallel control systems to follow the same trajectory accurately in order to address this issue it is necessary to achieve synchronous motion control for the two kinematical branches ensuring that the correct perpendicular position it’s kept by the mobile element during its motion on the two slides.

Transmittance tuning by particle chain polarization in electrowetting-driven droplets

PubMed Central

Fan, Shih-Kang; Chiu, Cheng-Pu; Huang, Po-Wen

2010-01-01

A tiny droplet containing nano∕microparticles commonly handled in digital microfluidic lab-on-a-chip is regarded as a micro-optical component with tunable transmittance at programmable positions for the application of micro-opto-fluidic-systems. Cross-scale electric manipulations of droplets on a millimeter scale as well as suspended particles on a micrometer scale are demonstrated by electrowetting-on-dielectric (EWOD) and particle chain polarization, respectively. By applying electric fields at proper frequency ranges, EWOD and polarization can be selectively achieved in designed and fabricated parallel plate devices. At low frequencies, the applied signal generates EWOD to pump suspension droplets. The evenly dispersed particles reflect and∕or absorb the incident light to exhibit a reflective or dark droplet. When sufficiently high frequencies are used on to the nonsegmented parallel electrodes, a uniform electric field is established across the liquid to polarize the dispersed neutral particles. The induced dipole moments attract the particles each other to form particle chains and increase the transmittance of the suspension, demonstrating a transmissive or bright droplet. In addition, the reflectance of the droplet is measured at various frequencies with different amplitudes. PMID:21267088

An efficient high-frequency analysis of modal reflection and transmission coefficients for a class of waveguide discontinuities

NASA Technical Reports Server (NTRS)

Pathak, P. H.; Altintas, A.

1988-01-01

A high-frequency analysis of electromagnetic modal reflection and transmission coefficients is presented for waveguide discontinuities formed by joining different waveguide sections. The analysis uses an extended version of the concept of geometrical theory of diffraction based equivalent edge currents in conjunction with the reciprocity theorem to describe interior scattering effects. If the waveguide modes and their associated modal rays can be found explicitly, general two- and three-dimensional waveguide geometries can be analyzed. Expressions are developed for two-dimensional reflection and transmission coefficients. Numerical results are given for a flanged, semi-infinite parallel plate waveguide and for the junction between two linearly tapered waveguides.

An internal crack parallel to the boundary of a nonhomogeneous half plane under thermal loading

NASA Astrophysics Data System (ADS)

Jin, Zhi-He; Noda, Naotake

1993-05-01

This paper considers the crack problem for a semi-infinite nonhomogeneous thermoelastic solid subjected to steady heat flux over the boundary. The crack faces are assumed to be insulated. The research is aimed at understanding the effect of nonhomogeneities of materials on stress intensity factors. By using the Fourier transform, the problem is reduced to a system of singular integral equations which are solved numerically. Results are presented illustrating the influence of the nonhomogeneity of the material on the stress intensity factors. Zero Mode I stress intensity factors are found for some groups of the material constants, which may be interesting for the understanding of compositions of advanced Functionally Gradient Materials.

The Kirillov picture for the Wigner particle

NASA Astrophysics Data System (ADS)

Gracia-Bondía, J. M.; Lizzi, F.; Várilly, J. C.; Vitale, P.

2018-06-01

We discuss the Kirillov method for massless Wigner particles, usually (mis)named ‘continuous spin’ or ‘infinite spin’ particles. These appear in Wigner’s classification of the unitary representations of the Poincaré group, labelled by elements of the enveloping algebra of the Poincaré Lie algebra. Now, the coadjoint orbit procedure introduced by Kirillov is a prelude to quantization. Here we exhibit for those particles the classical Casimir functions on phase space, in parallel to quantum representation theory. A good set of position coordinates are identified on the coadjoint orbits of the Wigner particles; the stabilizer subgroups and the symplectic structures of these orbits are also described. In memory of E C G Sudarshan.

Viscous cavity damping of a microlever in a simple fluid.

PubMed

Siria, A; Drezet, A; Marchi, F; Comin, F; Huant, S; Chevrier, J

2009-06-26

We consider the problem of oscillation damping in air of a thermally actuated microlever as it gradually approaches an infinite wall in parallel geometry. As the gap is decreased from 20 microm down to 400 nm, we observe the increasing damping of the lever Brownian motion in the fluid laminar regime. This manifests itself as a linear decrease in the lever quality factor accompanied by a dramatic softening of its resonance, and eventually leads to the freezing of the CL oscillation. We are able to quantitatively explain this behavior by analytically solving the Navier-Stokes equation with perfect slip boundary conditions. Our findings may have implications for microfluidics and micro- and nanoelectromechanical applications.

How normal is grammatical development in the right hemisphere following hemispherectomy? The root infinitive stage and beyond.

PubMed

Curtiss, Susan; de Bode, Stella

2003-08-01

We examined the morphosyntax of eight left hemispherectomized children at two different stages and compared it to MLU-matched normals. We found that the language of the hemispherectomies paralleled that of their MLU matches with respect to the specific morphosyntactic characteristics of each stage. Our findings provide strong evidence for the presence of functional categories in all early grammars and demonstrate that grammatical development, regardless of its neural substrate, is highly constrained by UG and follows a narrowly determined course. We discuss our findings within a neurobiological framework in which etiology defines the integrity of the remaining hemisphere, which in turn, determines its potential for linguistic reorganization and/or acquisition.

Cobotic architecture for prosthetics.

PubMed

Faulring, Eeic L; Colgate, J Edward; Peshkin, Michael A

2006-01-01

We envision cobotic infinitely-variable transmissions (IVTs) as an enabling technology for haptics and prosthetics that will allow for increases in the dynamic range of these devices while simultaneously permitting reductions in actuator size and power requirements. Use of cobotic IVTs eliminates the need to make compromises on output flow and effort, which are inherent to choosing a fixed transmission ratio drivetrain. The result is a mechanism with enhanced dynamic range that extends continuously from a completely clutched state to a highly backdrivable state. This high dynamic range allows cobotic devices to control impedance with a high level of fidelity. In this paper, we discuss these and other motivations for using parallel cobotic transmission architecture in prosthetic devices.

Stability of a viscous fluid in a rectangular cavity in the presence of a magnetic field

NASA Technical Reports Server (NTRS)

Liang, C. Y.; Hung, Y. Y.

1976-01-01

The stability of an electrically conducting fluid subjected to two dimensional disturbance was investigated. A physical system consisting of two parallel infinite vertical plates which are thermally insulated was studied. An external magnetic field of constant strength was applied to normal plates. The fluid was heated from below so that a steady temperature gradient was maintained in the fluid. The governing equations were derived by perturbation technique, and solutions were obtained by a modified Galerkin method. It was found that the presence of the magnetic field increases the stability of the physical system and instability can occur in the form of neutral or oscillatory instability.

Stability of vertical magnetic chains

PubMed Central

2017-01-01

A linear stability analysis is performed for a pair of coaxial vertical chains made from permanently magnetized balls under the influence of gravity. While one chain rises from the ground, the other hangs from above, with the remaining ends separated by a gap of prescribed length. Various boundary conditions are considered, as are situations in which the magnetic dipole moments in the two chains are parallel or antiparallel. The case of a single chain attached to the ground is also discussed. The stability of the system is examined with respect to three quantities: the number of balls in each chain, the length of the gap between the chains, and a single dimensionless parameter which embodies the competition between magnetic and gravitational forces. Asymptotic scaling laws involving these parameters are provided. The Hessian matrix is computed in exact form, allowing the critical parameter values at which the system loses stability and the respective eigenmodes to be determined up to machine precision. A comparison with simple experiments for a single chain attached to the ground shows good agreement. PMID:28293135

Stability of vertical magnetic chains

NASA Astrophysics Data System (ADS)

Schönke, Johannes; Fried, Eliot

2017-02-01

A linear stability analysis is performed for a pair of coaxial vertical chains made from permanently magnetized balls under the influence of gravity. While one chain rises from the ground, the other hangs from above, with the remaining ends separated by a gap of prescribed length. Various boundary conditions are considered, as are situations in which the magnetic dipole moments in the two chains are parallel or antiparallel. The case of a single chain attached to the ground is also discussed. The stability of the system is examined with respect to three quantities: the number of balls in each chain, the length of the gap between the chains, and a single dimensionless parameter which embodies the competition between magnetic and gravitational forces. Asymptotic scaling laws involving these parameters are provided. The Hessian matrix is computed in exact form, allowing the critical parameter values at which the system loses stability and the respective eigenmodes to be determined up to machine precision. A comparison with simple experiments for a single chain attached to the ground shows good agreement.

Solvation Thermodynamics of Oligoglycine with Respect to Chain Length and Flexibility.

PubMed

Drake, Justin A; Harris, Robert C; Pettitt, B Montgomery

2016-08-23

Oligoglycine is a backbone mimic for all proteins and is prevalent in the sequences of intrinsically disordered proteins. We have computed the absolute chemical potential of glycine oligomers at infinite dilution by simulation with the CHARMM36 and Amber ff12SB force fields. We performed a thermodynamic decomposition of the solvation free energy (ΔG(sol)) of Gly2-5 into enthalpic (ΔH(sol)) and entropic (ΔS(sol)) components as well as their van der Waals and electrostatic contributions. Gly2-5 was either constrained to a rigid/extended conformation or allowed to be completely flexible during simulations to assess the effects of flexibility on these thermodynamic quantities. For both rigid and flexible oligoglycine models, the decrease in ΔG(sol) with chain length is enthalpically driven with only weak entropic compensation. However, the apparent rates of decrease of ΔG(sol), ΔH(sol), ΔS(sol), and their elec and vdw components differ for the rigid and flexible models. Thus, we find solvation entropy does not drive aggregation for this system and may not explain the collapse of long oligoglycines. Additionally, both force fields yield very similar thermodynamic scaling relationships with respect to chain length despite both force fields generating different conformational ensembles of various oligoglycine chains. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Heat conduction in a chain of colliding particles with a stiff repulsive potential

NASA Astrophysics Data System (ADS)

Gendelman, Oleg V.; Savin, Alexander V.

2016-11-01

One-dimensional billiards, i.e., a chain of colliding particles with equal masses, is a well-known example of a completely integrable system. Billiards with different particle masses is generically not integrable, but it still exhibits divergence of a heat conduction coefficient (HCC) in the thermodynamic limit. Traditional billiards models imply instantaneous (zero-time) collisions between the particles. We relax this condition of instantaneous impact and consider heat transport in a chain of stiff colliding particles with the power-law potential of the nearest-neighbor interaction. The instantaneous collisions correspond to the limit of infinite power in the interaction potential; for finite powers, the interactions take nonzero time. This modification of the model leads to a profound physical consequence—the probability of multiple (in particular triple) -particle collisions becomes nonzero. Contrary to the integrable billiards of equal particles, the modified model exhibits saturation of the heat conduction coefficient for a large system size. Moreover, the identification of scattering events with triple-particle collisions leads to a simple definition of the characteristic mean free path and a kinetic description of heat transport. This approach allows us to predict both the temperature and density dependencies for the HCC limit values. The latter dependence is quite counterintuitive—the HCC is inversely proportional to the particle density in the chain. Both predictions are confirmed by direct numerical simulations.

Elasticity and photoelasticity relationships for polyethylene terephthalate fiber networks by molecular simulation

NASA Astrophysics Data System (ADS)

Nayak, Kapileswar; Das, Sushanta; Nanavati, Hemant

2008-01-01

We present a framework for the development of elasticity and photoelasticity relationships for polyethylene terephthalate fiber networks, incorporating aspects of the primary molecular structure. Semicrystalline polymeric fiber networks are modeled as sequentially arranged crystalline and amorphous regions. Rotational isomeric states-Monte Carlo simulations of amorphous chains of up to 360 bonds (degree of polymerization, DP =60), confined between and bridging infinite impenetrable crystalline walls, have been characterized by Ω, the probability density of the intercrystal separation h, and Δβ, the polarizability anisotropy. lnΩ and Δβ have been modeled as functions of h, yielding the chain deformation relationships. The development has been extended to the fiber network to yield the photoelasticity relationships. We execute our framework by fitting to experimental stress-elongation data and employing the single fitted parameter to directly predict the birefringence-elongation behavior, without any further fitting. Incorporating the effect of strain-induced crystallization into the framework makes it physically more meaningful and yields accurate predictions of the birefringence-elongation behavior.

K0.78Na0.22MoO2AsO4

PubMed Central

Jouini, Raja; Bouzidi, Chahira; Zid, Mohamed Faouzi; Driss, Ahmed

2013-01-01

The title compound, potassium sodium dioxidomolybden­um(VI) arsenate, K0.78Na0.22MoO2AsO4, was synthesized by a solid-state reaction route. The structure is built up from corner-sharing MoO6 octa­hedra and AsO4 tetra­hedra, creating infinite [MoAsO8]∞ chains running along the b-axis direction. As, Mo and all but one O atom are on special positions (4c) with m symmetry and K (occupancy 0.78) is on a position (4a) of -1 in the tunnels. The possible motion of the alkali cations has been investigated by means of the bond-valance sum (BVS) model. The simulation shows that the Na+ motion appears to be easier mainly along the b-axis direction. Structural relationships between the different compounds of the AMoO2AsO4 (A = Ag, Li, Na, K, Rb) series and MXO8 (M = V; X = P, As) chains are discussed. PMID:24109253

Exact Markov chain and approximate diffusion solution for haploid genetic drift with one-way mutation.

PubMed

Hössjer, Ola; Tyvand, Peder A; Miloh, Touvia

2016-02-01

The classical Kimura solution of the diffusion equation is investigated for a haploid random mating (Wright-Fisher) model, with one-way mutations and initial-value specified by the founder population. The validity of the transient diffusion solution is checked by exact Markov chain computations, using a Jordan decomposition of the transition matrix. The conclusion is that the one-way diffusion model mostly works well, although the rate of convergence depends on the initial allele frequency and the mutation rate. The diffusion approximation is poor for mutation rates so low that the non-fixation boundary is regular. When this happens we perturb the diffusion solution around the non-fixation boundary and obtain a more accurate approximation that takes quasi-fixation of the mutant allele into account. The main application is to quantify how fast a specific genetic variant of the infinite alleles model is lost. We also discuss extensions of the quasi-fixation approach to other models with small mutation rates. Copyright © 2015 Elsevier Inc. All rights reserved.

Numerical estimation of structure constants in the three-dimensional Ising conformal field theory through Markov chain uv sampler

NASA Astrophysics Data System (ADS)

Herdeiro, Victor

2017-09-01

Herdeiro and Doyon [Phys. Rev. E 94, 043322 (2016), 10.1103/PhysRevE.94.043322] introduced a numerical recipe, dubbed uv sampler, offering precise estimations of the conformal field theory (CFT) data of the planar two-dimensional (2D) critical Ising model. It made use of scale invariance emerging at the critical point in order to sample finite sublattice marginals of the infinite plane Gibbs measure of the model by producing holographic boundary distributions. The main ingredient of the Markov chain Monte Carlo sampler is the invariance under dilation. This paper presents a generalization to higher dimensions with the critical 3D Ising model. This leads to numerical estimations of a subset of the CFT data—scaling weights and structure constants—through fitting of measured correlation functions. The results are shown to agree with the recent most precise estimations from numerical bootstrap methods [Kos, Poland, Simmons-Duffin, and Vichi, J. High Energy Phys. 08 (2016) 036, 10.1007/JHEP08(2016)036].

catena-Poly[[bis­(4-carboxy­cyclo­hexane­carboxyl­ato-κ2 O 1,O 1′)cadmium(II)]-μ-1,4-bis­(imidazol-1-ylmeth­yl)benzene-κ2 N 3:N 3′

PubMed Central

Li, Bing-Bing; Xiao, Bo

2009-01-01

In the title coordination polymer, [Cd(C8H11O4)2(C14H14N4)]n, the Cd atom (site symmetry 2) is six-coordin­ated by two O,O′-bidentate 4-carboxy­cyclo­hexa­necarboxyl­ate (Hchdc) ligands and two N atoms from two different 1,4-bis­(imidazol-1-ylmeth­yl)benzene (1,4-bix) mol­ecules in a very distorted cis-CdN2O4 octa­hedral environment. The 1,4-bix mol­ecules act as bridging ligands that bind two CdII atoms, thus forming an infinite chain propagating in [100], which is decorated by the Hchdc anions. The structure is completed by O—H⋯O hydrogen bonds, which link the chains together. PMID:21582692

Probing the statistics of transport in the Hénon Map

NASA Astrophysics Data System (ADS)

Alus, O.; Fishman, S.; Meiss, J. D.

2016-09-01

The phase space of an area-preserving map typically contains infinitely many elliptic islands embedded in a chaotic sea. Orbits near the boundary of a chaotic region have been observed to stick for long times, strongly influencing their transport properties. The boundary is composed of invariant "boundary circles." We briefly report recent results of the distribution of rotation numbers of boundary circles for the Hénon quadratic map and show that the probability of occurrence of small integer entries of their continued fraction expansions is larger than would be expected for a number chosen at random. However, large integer entries occur with probabilities distributed proportionally to the random case. The probability distributions of ratios of fluxes through island chains is reported as well. These island chains are neighbours in the sense of the Meiss-Ott Markov-tree model. Two distinct universality families are found. The distributions of the ratio between the flux and orbital period are also presented. All of these results have implications for models of transport in mixed phase space.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koch, D.; Fertitta, E.; Paulus, B.

Due to the importance of both static and dynamical correlation in the bond formation, low-dimensional beryllium systems constitute interesting case studies to test correlation methods. Aiming to describe the whole dissociation curve of extended Be systems we chose to apply the method of increments (MoI) in its multireference (MR) formalism. To gain insight into the main characteristics of the wave function, we started by focusing on the description of small Be chains using standard quantum chemical methods. In a next step we applied the MoI to larger beryllium systems, starting from the Be{sub 6} ring. The complete active space formalismmore » was employed and the results were used as reference for local MR calculations of the whole dissociation curve. Although this is a well-established approach for systems with limited multireference character, its application regarding the description of whole dissociation curves requires further testing. Subsequent to the discussion of the role of the basis set, the method was finally applied to larger rings and extrapolated to an infinite chain.« less

MC3: Multi-core Markov-chain Monte Carlo code

NASA Astrophysics Data System (ADS)

Cubillos, Patricio; Harrington, Joseph; Lust, Nate; Foster, AJ; Stemm, Madison; Loredo, Tom; Stevenson, Kevin; Campo, Chris; Hardin, Matt; Hardy, Ryan

2016-10-01

MC3 (Multi-core Markov-chain Monte Carlo) is a Bayesian statistics tool that can be executed from the shell prompt or interactively through the Python interpreter with single- or multiple-CPU parallel computing. It offers Markov-chain Monte Carlo (MCMC) posterior-distribution sampling for several algorithms, Levenberg-Marquardt least-squares optimization, and uniform non-informative, Jeffreys non-informative, or Gaussian-informative priors. MC3 can share the same value among multiple parameters and fix the value of parameters to constant values, and offers Gelman-Rubin convergence testing and correlated-noise estimation with time-averaging or wavelet-based likelihood estimation methods.

Ab initio optimization principle for the ground states of translationally invariant strongly correlated quantum lattice models.

PubMed

Ran, Shi-Ju

2016-05-01

In this work, a simple and fundamental numeric scheme dubbed as ab initio optimization principle (AOP) is proposed for the ground states of translational invariant strongly correlated quantum lattice models. The idea is to transform a nondeterministic-polynomial-hard ground-state simulation with infinite degrees of freedom into a single optimization problem of a local function with finite number of physical and ancillary degrees of freedom. This work contributes mainly in the following aspects: (1) AOP provides a simple and efficient scheme to simulate the ground state by solving a local optimization problem. Its solution contains two kinds of boundary states, one of which play the role of the entanglement bath that mimics the interactions between a supercell and the infinite environment, and the other gives the ground state in a tensor network (TN) form. (2) In the sense of TN, a novel decomposition named as tensor ring decomposition (TRD) is proposed to implement AOP. Instead of following the contraction-truncation scheme used by many existing TN-based algorithms, TRD solves the contraction of a uniform TN in an opposite way by encoding the contraction in a set of self-consistent equations that automatically reconstruct the whole TN, making the simulation simple and unified; (3) AOP inherits and develops the ideas of different well-established methods, including the density matrix renormalization group (DMRG), infinite time-evolving block decimation (iTEBD), network contractor dynamics, density matrix embedding theory, etc., providing a unified perspective that is previously missing in this fields. (4) AOP as well as TRD give novel implications to existing TN-based algorithms: A modified iTEBD is suggested and the two-dimensional (2D) AOP is argued to be an intrinsic 2D extension of DMRG that is based on infinite projected entangled pair state. This paper is focused on one-dimensional quantum models to present AOP. The benchmark is given on a transverse Ising chain and 2D classical Ising model, showing the remarkable efficiency and accuracy of the AOP.

Li0.5Al0.5Mg2(MoO4)3

PubMed Central

Ennajeh, Ines; Zid, Mohamed Faouzi; Driss, Ahmed

2013-01-01

The title compound, lithium/aluminium dimagnesium tetra­kis­[orthomolybdate(VI)], was prepared by a solid-state reaction route. The crystal structure is built up from MgO6 octa­hedra and MoO4 tetra­hedra sharing corners and edges, forming two types of chains running along [100]. These chains are linked into layers parallel to (010) and finally linked by MoO4 tetra­hedra into a three-dimensional framework structure with channels parallel to [001] in which lithium and aluminium cations equally occupy the same position within a distorted trigonal–bipyramidal coordination environment. The title structure is isotypic with LiMgIn(MoO4)3, with the In site becoming an Mg site and the fully occupied Li site a statistically occupied Li/Al site in the title structure. PMID:24426975

Catabolism of Branched Chain Amino Acids Contributes Significantly to Synthesis of Odd-Chain and Even-Chain Fatty Acids in 3T3-L1 Adipocytes.

PubMed

Crown, Scott B; Marze, Nicholas; Antoniewicz, Maciek R

2015-01-01

The branched chain amino acids (BCAA) valine, leucine and isoleucine have been implicated in a number of diseases including obesity, insulin resistance, and type 2 diabetes mellitus, although the mechanisms are still poorly understood. Adipose tissue plays an important role in BCAA homeostasis by actively metabolizing circulating BCAA. In this work, we have investigated the link between BCAA catabolism and fatty acid synthesis in 3T3-L1 adipocytes using parallel 13C-labeling experiments, mass spectrometry and model-based isotopomer data analysis. Specifically, we performed parallel labeling experiments with four fully 13C-labeled tracers, [U-13C]valine, [U-13C]leucine, [U-13C]isoleucine and [U-13C]glutamine. We measured mass isotopomer distributions of fatty acids and intracellular metabolites by GC-MS and analyzed the data using the isotopomer spectral analysis (ISA) framework. We demonstrate that 3T3-L1 adipocytes accumulate significant amounts of even chain length (C14:0, C16:0 and C18:0) and odd chain length (C15:0 and C17:0) fatty acids under standard cell culture conditions. Using a novel GC-MS method, we demonstrate that propionyl-CoA acts as the primer on fatty acid synthase for the production of odd chain fatty acids. BCAA contributed significantly to the production of all fatty acids. Leucine and isoleucine contributed at least 25% to lipogenic acetyl-CoA pool, and valine and isoleucine contributed 100% to lipogenic propionyl-CoA pool. Our results further suggest that low activity of methylmalonyl-CoA mutase and mass action kinetics of propionyl-CoA on fatty acid synthase result in high rates of odd chain fatty acid synthesis in 3T3-L1 cells. Overall, this work provides important new insights into the connection between BCAA catabolism and fatty acid synthesis in adipocytes and underscores the high capacity of adipocytes for metabolizing BCAA.

Levitation properties of maglev systems using soft ferromagnets

NASA Astrophysics Data System (ADS)

Huang, Chen-Guang; Zhou, You-He

2015-03-01

Soft ferromagnets are widely used as flux-concentration materials in the design of guideways for superconducting magnetic levitation transport systems. In order to fully understand the influence of soft ferromagnets on the levitation performance, in this work we apply a numerical model based on the functional minimization method and the Bean’s critical state model to study the levitation properties of an infinitely long superconductor immersed in the magnetic field created by a guideway of different sets of infinitely long parallel permanent magnets with soft ferromagnets between them. The levitation force, guidance force, magnetic stiffness and magnetic pole density are calculated considering the coupling between the superconductor and soft ferromagnets. The results show that the levitation performance is closely associated with the permanent magnet configuration and with the location and dimension of the soft ferromagnets. Introducing the soft ferromagnet with a certain width in a few configurations always decreases the levitation force. However, for most configurations, the soft ferromagnets contribute to improve the levitation performance only when they have particular locations and dimensions in which the optimized location and thickness exist to increase the levitation force the most. Moreover, if the superconductor is laterally disturbed, the presence of soft ferromagnets can effectively improve the lateral stability for small lateral displacement and reduce the degradation of levitation force.

Full-Potential Modeling of Blade-Vortex Interactions. Degree awarded by George Washington Univ., Feb. 1987

NASA Technical Reports Server (NTRS)

Jones, Henry E.

1997-01-01

A study of the full-potential modeling of a blade-vortex interaction was made. A primary goal of this study was to investigate the effectiveness of the various methods of modeling the vortex. The model problem restricts the interaction to that of an infinite wing with an infinite line vortex moving parallel to its leading edge. This problem provides a convenient testing ground for the various methods of modeling the vortex while retaining the essential physics of the full three-dimensional interaction. A full-potential algorithm specifically tailored to solve the blade-vortex interaction (BVI) was developed to solve this problem. The basic algorithm was modified to include the effect of a vortex passing near the airfoil. Four different methods of modeling the vortex were used: (1) the angle-of-attack method, (2) the lifting-surface method, (3) the branch-cut method, and (4) the split-potential method. A side-by-side comparison of the four models was conducted. These comparisons included comparing generated velocity fields, a subcritical interaction, and a critical interaction. The subcritical and critical interactions are compared with experimentally generated results. The split-potential model was used to make a survey of some of the more critical parameters which affect the BVI.

Size-scaling behaviour of the electronic polarizability of one-dimensional interacting systems

NASA Astrophysics Data System (ADS)

Chiappe, G.; Louis, E.; Vergés, J. A.

2018-05-01

Electronic polarizability of finite chains is accurately calculated from the total energy variation of the system produced by small but finite static electric fields applied along the chain direction. Normalized polarizability, that is, polarizability divided by chain length, diverges as the second power of length for metallic systems but approaches a constant value for insulating systems. This behaviour provides a very convenient way to characterize the wave-function malleability of finite systems as it avoids the need of attaching infinite contacts to the chain ends. Hubbard model calculations at half filling show that the method works for a small U  =  1 interaction value that corresponds to a really small spectral gap of 0.005 (hopping t  =  ‑1 is assumed). Once successfully checked, the method has been applied to the long-range hopping model of Gebhard and Ruckenstein showing 1/r hopping decay (Gebhard and Ruckenstein 1992 Phys. Rev. Lett. 68 244; Gebhard et al 1994 Phys. Rev. B 49 10926). Metallicity for U values below the reported metal-insulator transition is obtained but the surprise comes for U values larger than the critical one (when a gap appears in the spectral density of states) because a steady increase of the normalized polarizability with size is obtained. This critical size-scaling behaviour can be understood as corresponding to a molecule which polarizability is unbounded. We have checked that a real transfer of charge from one chain end to the opposite occurs as a response to very small electric fields in spite of the existence of a large gap of the order of U for one-particle excitations. Finally, ab initio quantum chemistry calculations of realistic poly-acetylene chains prove that the occurrence of such critical behaviour in real systems is unlikely.

GPU-accelerated low-latency real-time searches for gravitational waves from compact binary coalescence

NASA Astrophysics Data System (ADS)

Liu, Yuan; Du, Zhihui; Chung, Shin Kee; Hooper, Shaun; Blair, David; Wen, Linqing

2012-12-01

We present a graphics processing unit (GPU)-accelerated time-domain low-latency algorithm to search for gravitational waves (GWs) from coalescing binaries of compact objects based on the summed parallel infinite impulse response (SPIIR) filtering technique. The aim is to facilitate fast detection of GWs with a minimum delay to allow prompt electromagnetic follow-up observations. To maximize the GPU acceleration, we apply an efficient batched parallel computing model that significantly reduces the number of synchronizations in SPIIR and optimizes the usage of the memory and hardware resource. Our code is tested on the CUDA ‘Fermi’ architecture in a GTX 480 graphics card and its performance is compared with a single core of Intel Core i7 920 (2.67 GHz). A 58-fold speedup is achieved while giving results in close agreement with the CPU implementation. Our result indicates that it is possible to conduct a full search for GWs from compact binary coalescence in real time with only one desktop computer equipped with a Fermi GPU card for the initial LIGO detectors which in the past required more than 100 CPUs.

On the Transition from Two-Dimensional to Three-Dimensional MHD Turbulence

NASA Technical Reports Server (NTRS)

Thess, A.; Zikanov, Oleg

2004-01-01

We report a theoretical investigation of the robustness of two-dimensional inviscid MHD flows at low magnetic Reynolds numbers with respect to three-dimensional perturbations. We analyze three model problems, namely flow in the interior of a triaxial ellipsoid, an unbounded vortex with elliptical streamlines, and a vortex sheet parallel to the magnetic field. We demonstrate that motion perpendicular to the magnetic field with elliptical streamlines becomes unstable with respect to the elliptical instability once the velocity has reached a critical magnitude whose value tends to zero as the eccentricity of the streamlines becomes large. Furthermore, vortex sheets parallel to the magnetic field, which are unstable for any velocity and any magnetic field, are found to emit eddies with vorticity perpendicular to the magnetic field and with an aspect ratio proportional to N(sup 1/2). The results suggest that purely two-dimensional motion without Joule energy dissipation is a singular type of flow which does not represent the asymptotic behaviour of three-dimensional MHD turbulence in the limit of infinitely strong magnetic fields.

Material Implementation of Hyperincursive Field on Slime Mold Computer

NASA Astrophysics Data System (ADS)

Aono, Masashi; Gunji, Yukio-Pegio

2004-08-01

"Elementary Conflictable Cellular Automaton (ECCA)" was introduced by Aono and Gunji as a problematic computational syntax embracing the non-deterministic/non-algorithmic property due to its hyperincursivity and nonlocality. Although ECCA's hyperincursive evolution equation indicates the occurrence of the deadlock/infinite-loop, we do not consider that this problem declares the fundamental impossibility of implementing ECCA materially. Dubois proposed to call a computing system where uncertainty/contradiction occurs "the hyperincursive field". In this paper we introduce a material implementation of the hyperincursive field by using plasmodia of the true slime mold Physarum polycephalum. The amoeboid organism is adopted as a computing media of ECCA slime mold computer (ECCA-SMC) mainly because; it is a parallel non-distributed system whose locally branched tips (components) can act in parallel with asynchronism and nonlocal correlation. A notable characteristic of ECCA-SMC is that a cell representing a spatio-temporal segment of computation is occupied (overlapped) redundantly by multiple spatially adjacent computing operations and by temporally successive computing events. The overlapped time representation may contribute to the progression of discussions on unconventional notions of the time.

Molecular-dynamics simulations of self-assembled monolayers (SAM) on parallel computers

NASA Astrophysics Data System (ADS)

Vemparala, Satyavani

The purpose of this dissertation is to investigate the properties of self-assembled monolayers, particularly alkanethiols and Poly (ethylene glycol) terminated alkanethiols. These simulations are based on realistic interatomic potentials and require scalable and portable multiresolution algorithms implemented on parallel computers. Large-scale molecular dynamics simulations of self-assembled alkanethiol monolayer systems have been carried out using an all-atom model involving a million atoms to investigate their structural properties as a function of temperature, lattice spacing and molecular chain-length. Results show that the alkanethiol chains tilt from the surface normal by a collective angle of 25° along next-nearest neighbor direction at 300K. At 350K the system transforms to a disordered phase characterized by small tilt angle, flexible tilt direction, and random distribution of backbone planes. With increasing lattice spacing, a, the tilt angle increases rapidly from a nearly zero value at a = 4.7A to as high as 34° at a = 5.3A at 300K. We also studied the effect of end groups on the tilt structure of SAM films. We characterized the system with respect to temperature, the alkane chain length, lattice spacing, and the length of the end group. We found that the gauche defects were predominant only in the tails, and the gauche defects increased with the temperature and number of EG units. Effect of electric field on the structure of poly (ethylene glycol) (PEG) terminated alkanethiol self assembled monolayer (SAM) on gold has been studied using parallel molecular dynamics method. An applied electric field triggers a conformational transition from all-trans to a mostly gauche conformation. The polarity of the electric field has a significant effect on the surface structure of PEG leading to a profound effect on the hydrophilicity of the surface. The electric field applied anti-parallel to the surface normal causes a reversible transition to an ordered state in which the oxygen atoms are exposed. On the other hand, an electric field applied in a direction parallel to the surface normal introduces considerable disorder in the system and the oxygen atoms are buried inside.

Concentration and saturation effects of tethered polymer chains on adsorbing surfaces

NASA Astrophysics Data System (ADS)

Descas, Radu; Sommer, Jens-Uwe; Blumen, Alexander

2006-12-01

We consider end-grafted chains at an adsorbing surface under good solvent conditions using Monte Carlo simulations and scaling arguments. Grafting of chains allows us to fix the surface concentration and to study a wide range of surface concentrations from the undersaturated state of the surface up to the brushlike regime. The average extension of single chains in the direction parallel and perpendicular to the surface is analyzed using scaling arguments for the two-dimensional semidilute surface state according to Bouchaud and Daoud [J. Phys. (Paris) 48, 1991 (1987)]. We find good agreement with the scaling predictions for the scaling in the direction parallel to the surface and for surface concentrations much below the saturation concentration (dense packing of adsorption blobs). Increasing the grafting density we study the saturation effects and the oversaturation of the adsorption layer. In order to account for the effect of excluded volume on the adsorption free energy we introduce a new scaling variable related with the saturation concentration of the adsorption layer (saturation scaling). We show that the decrease of the single chain order parameter (the fraction of adsorbed monomers on the surface) with increasing concentration, being constant in the ideal semidilute surface state, is properly described by saturation scaling only. Furthermore, the simulation results for the chains' extension from higher surface concentrations up to the oversaturated state support the new scaling approach. The oversaturated state can be understood using a geometrical model which assumes a brushlike layer on top of a saturated adsorption layer. We provide evidence that adsorbed polymer layers are very sensitive to saturation effects, which start to influence the semidilute surface scaling even much below the saturation threshold.

Vapor-liquid equilibrium and critical asymmetry of square well and short square well chain fluids.

PubMed

Li, Liyan; Sun, Fangfang; Chen, Zhitong; Wang, Long; Cai, Jun

2014-08-07

The critical behavior of square well fluids with variable interaction ranges and of short square well chain fluids have been investigated by grand canonical ensemble Monte Carlo simulations. The critical temperatures and densities were estimated by a finite-size scaling analysis with the help of histogram reweighting technique. The vapor-liquid coexistence curve in the near-critical region was determined using hyper-parallel tempering Monte Carlo simulations. The simulation results for coexistence diameters show that the contribution of |t|(1-α) to the coexistence diameter dominates the singular behavior in all systems investigated. The contribution of |t|(2β) to the coexistence diameter is larger for the system with a smaller interaction range λ. While for short square well chain fluids, longer the chain length, larger the contribution of |t|(2β). The molecular configuration greatly influences the critical asymmetry: a short soft chain fluid shows weaker critical asymmetry than a stiff chain fluid with same chain length.

Chain representations of Open Quantum Systems and Lieb-Robinson like bounds for the dynamics

NASA Astrophysics Data System (ADS)

Woods, Mischa

2013-03-01

This talk is concerned with the mapping of the Hamiltonian of open quantum systems onto chain representations, which forms the basis for a rigorous theory of the interaction of a system with its environment. This mapping progresses as an interaction which gives rise to a sequence of residual spectral densities of the system. The rigorous mathematical properties of this mapping have been unknown so far. Here we develop the theory of secondary measures to derive an analytic, expression for the sequence solely in terms of the initial measure and its associated orthogonal polynomials of the first and second kind. These mappings can be thought of as taking a highly nonlocal Hamiltonian to a local Hamiltonian. In the latter, a Lieb-Robinson like bound for the dynamics of the open quantum system makes sense. We develop analytical bounds on the error to observables of the system as a function of time when the semi-infinite chain in truncated at some finite length. The fact that this is possible shows that there is a finite ``Speed of sound'' in these chain representations. This has many implications of the simulatability of open quantum systems of this type and demonstrates that a truncated chain can faithfully reproduce the dynamics at shorter times. These results make a significant and mathematically rigorous contribution to the understanding of the theory of open quantum systems; and pave the way towards the efficient simulation of these systems, which within the standard methods, is often an intractable problem. EPSRC CDT in Controlled Quantum Dynamics, EU STREP project and Alexander von Humboldt Foundation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Jing-Yun, E-mail: jyunwu@ncnu.edu.tw; Tsai, Chi-Jou; Chang, Ching-Yun

A Zn(II)−salicylaldimine complex [Zn(L{sup salpyca})(H{sub 2}O)]{sub n} (1, where H{sub 2}L{sup salpyca}=4-hydroxy-3-(((pyridin-2-yl)methylimino)methyl)benzoic acid), with a one-dimensional (1D) chain structure, has been successfully converted to a discrete Ni(II)−salicylaldimine complex [Ni(L{sup salpyca})(H{sub 2}O){sub 3}] (2) and an infinite Cu(II)−salicylaldimine complex ([Cu(L{sup salpyca})]·3H{sub 2}O){sub n} (3) through a metal-ion exchange induced structural transformation process. However, such processes do not worked by Mn(II) and Co(II) ions. Solid-state structure analyses reveal that complexes 1–3 form comparable coordinative or supramolecular zigzag chains running along the crystallographic [201] direction. In addition, replacing Zn(II) ion by Ni(II) and Cu(II) ions caused changes in coordination environment and sphere ofmore » metal centers, from a 5-coordinate intermediate geometry of square pyramidal and trigonal bipyramidal in 1 to a 6-coordinate octahedral geometry in 2, and to a 4-coordiante square planar geometry in 3. This study shows that metal-ion exchange serves as a very efficient way of forming new coordination complexes that may not be obtained through direct synthesis. - Graphical abstract: A Zn(II)−salicylaldimine zigzag chain has been successfully converted to a Ni(II)−salicylaldimine supramolecular zigzag chain and a Cu(II)−salicylaldimine coordinative zigzag chain through metal-ion exchange induced structural transformations, which is not achieved by Mn(II) and Co(II) ions.« less

Parallel-SymD: A Parallel Approach to Detect Internal Symmetry in Protein Domains.

PubMed

Jha, Ashwani; Flurchick, K M; Bikdash, Marwan; Kc, Dukka B

2016-01-01

Internally symmetric proteins are proteins that have a symmetrical structure in their monomeric single-chain form. Around 10-15% of the protein domains can be regarded as having some sort of internal symmetry. In this regard, we previously published SymD (symmetry detection), an algorithm that determines whether a given protein structure has internal symmetry by attempting to align the protein to its own copy after the copy is circularly permuted by all possible numbers of residues. SymD has proven to be a useful algorithm to detect symmetry. In this paper, we present a new parallelized algorithm called Parallel-SymD for detecting symmetry of proteins on clusters of computers. The achieved speedup of the new Parallel-SymD algorithm scales well with the number of computing processors. Scaling is better for proteins with a larger number of residues. For a protein of 509 residues, a speedup of 63 was achieved on a parallel system with 100 processors.

Parallel-SymD: A Parallel Approach to Detect Internal Symmetry in Protein Domains

PubMed Central

Jha, Ashwani; Flurchick, K. M.; Bikdash, Marwan

2016-01-01

Internally symmetric proteins are proteins that have a symmetrical structure in their monomeric single-chain form. Around 10–15% of the protein domains can be regarded as having some sort of internal symmetry. In this regard, we previously published SymD (symmetry detection), an algorithm that determines whether a given protein structure has internal symmetry by attempting to align the protein to its own copy after the copy is circularly permuted by all possible numbers of residues. SymD has proven to be a useful algorithm to detect symmetry. In this paper, we present a new parallelized algorithm called Parallel-SymD for detecting symmetry of proteins on clusters of computers. The achieved speedup of the new Parallel-SymD algorithm scales well with the number of computing processors. Scaling is better for proteins with a larger number of residues. For a protein of 509 residues, a speedup of 63 was achieved on a parallel system with 100 processors. PMID:27747230

Parallel DSMC Solution of Three-Dimensional Flow Over a Finite Flat Plate

NASA Technical Reports Server (NTRS)

Nance, Robert P.; Wilmoth, Richard G.; Moon, Bongki; Hassan, H. A.; Saltz, Joel

1994-01-01

This paper describes a parallel implementation of the direct simulation Monte Carlo (DSMC) method. Runtime library support is used for scheduling and execution of communication between nodes, and domain decomposition is performed dynamically to maintain a good load balance. Performance tests are conducted using the code to evaluate various remapping and remapping-interval policies, and it is shown that a one-dimensional chain-partitioning method works best for the problems considered. The parallel code is then used to simulate the Mach 20 nitrogen flow over a finite-thickness flat plate. It is shown that the parallel algorithm produces results which compare well with experimental data. Moreover, it yields significantly faster execution times than the scalar code, as well as very good load-balance characteristics.

Supply chain dynamics in healthcare services.

PubMed

Samuel, Cherian; Gonapa, Kasiviswanadh; Chaudhary, P K; Mishra, Ananya

2010-01-01

The purpose of this paper is to analyse health service supply chain systems. A great deal of literature is available on supply chain management in finished goods inventory situations; however, little research exists on managing service capacity when finished goods inventories are absent. System dynamics models for a typical service-oriented supply chain such as healthcare processes are developed, wherein three service stages are presented sequentially. Just like supply chains with finished goods inventory, healthcare service supply chains also show dynamic behaviour. Comparing options, service reduction, and capacity adjustment delays showed that reducing capacity adjustment and service delays gives better results. The study is confined to health service-oriented supply chains. Further work includes extending the study to service-oriented supply chains with parallel processing, i.e. having more than one stage to perform a similar operation and also to study the behaviour in service-oriented supply chains that have re-entrant orders and applications. Specific case studies can also be developed to reveal factors relevant to particular service-oriented supply chains. The paper explains the bullwhip effect in healthcare service-oriented supply chains. Reducing stages and capacity adjustment are strategic options for service-oriented supply chains. The paper throws light on policy options for managing healthcare service-oriented supply chain dynamics.

catena-Poly[[[4,6-bis-(2-pyrid-yl)-1,3,5-triazin-2-olato]copper(II)]-μ-chlorido].

PubMed

Cao, Man-Li

2011-06-01

The title compound, [Cu(C(13)H(8)N(5)O)Cl](n), has a chain structure parallel to [100] with Cu(2+) cations in a trigonal-bipyramidal coordination environment. The ligand adopts a tridentate tripyridyl coordination mode and a chloride ion acts as a bridge. The chains are linked via weak C-H⋯O and C-H⋯Cl hydrogen bonds into a three-dimensional supra-molecular network.

Anisotropy effects in the ferromagnetic quantum chain systems (C 6H 11NH 3)CuCl 3 (CHAC) and (C 6H 11NH 3)CuBr 3 (CHAB)

NASA Astrophysics Data System (ADS)

Kopinga, K.; Nishihara, H.; De Jonge, W. J. M.

1983-02-01

Heat capacity and magnetization measurements on the title compounds revealed that they are very good approximations of a ferromagnetic S = {1}/{2} Heisenberg chain system. The small anisotropy present in these compounds gives rise to very pronounced cross-over effects. In CHAC, the cross-over temperature is increased by a magnetic field parallel to the easy axis.

Scaling up antiretroviral therapy in Uganda: using supply chain management to appraise health systems strengthening

PubMed Central

2011-01-01

Background Strengthened national health systems are necessary for effective and sustained expansion of antiretroviral therapy (ART). ART and its supply chain management in Uganda are largely based on parallel and externally supported efforts. The question arises whether systems are being strengthened to sustain access to ART. This study applies systems thinking to assess supply chain management, the role of external support and whether investments create the needed synergies to strengthen health systems. Methods This study uses the WHO health systems framework and examines the issues of governance, financing, information, human resources and service delivery in relation to supply chain management of medicines and the technologies. It looks at links and causal chains between supply chain management for ART and the national supply system for essential drugs. It combines data from the literature and key informant interviews with observations at health service delivery level in a study district. Results Current drug supply chain management in Uganda is characterized by parallel processes and information systems that result in poor quality and inefficiencies. Less than expected health system performance, stock outs and other shortages affect ART and primary care in general. Poor performance of supply chain management is amplified by weak conditions at all levels of the health system, including the areas of financing, governance, human resources and information. Governance issues include the lack to follow up initial policy intentions and a focus on narrow, short-term approaches. Conclusion The opportunity and need to use ART investments for an essential supply chain management and strengthened health system has not been exploited. By applying a systems perspective this work indicates the seriousness of missing system prerequisites. The findings suggest that root causes and capacities across the system have to be addressed synergistically to enable systems that can match and accommodate investments in disease-specific interventions. The multiplicity and complexity of existing challenges require a long-term and systems perspective essentially in contrast to the current short term and program-specific nature of external assistance. PMID:21806826

Chaining direct memory access data transfer operations for compute nodes in a parallel computer

DOEpatents

Archer, Charles J.; Blocksome, Michael A.

2010-09-28

Methods, systems, and products are disclosed for chaining DMA data transfer operations for compute nodes in a parallel computer that include: receiving, by an origin DMA engine on an origin node in an origin injection FIFO buffer for the origin DMA engine, a RGET data descriptor specifying a DMA transfer operation data descriptor on the origin node and a second RGET data descriptor on the origin node, the second RGET data descriptor specifying a target RGET data descriptor on the target node, the target RGET data descriptor specifying an additional DMA transfer operation data descriptor on the origin node; creating, by the origin DMA engine, an RGET packet in dependence upon the RGET data descriptor, the RGET packet containing the DMA transfer operation data descriptor and the second RGET data descriptor; and transferring, by the origin DMA engine to a target DMA engine on the target node, the RGET packet.

Automatic target recognition apparatus and method

DOEpatents

Baumgart, Chris W.; Ciarcia, Christopher A.

2000-01-01

An automatic target recognition apparatus (10) is provided, having a video camera/digitizer (12) for producing a digitized image signal (20) representing an image containing therein objects which objects are to be recognized if they meet predefined criteria. The digitized image signal (20) is processed within a video analysis subroutine (22) residing in a computer (14) in a plurality of parallel analysis chains such that the objects are presumed to be lighter in shading than the background in the image in three of the chains and further such that the objects are presumed to be darker than the background in the other three chains. In two of the chains the objects are defined by surface texture analysis using texture filter operations. In another two of the chains the objects are defined by background subtraction operations. In yet another two of the chains the objects are defined by edge enhancement processes. In each of the analysis chains a calculation operation independently determines an error factor relating to the probability that the objects are of the type which should be recognized, and a probability calculation operation combines the results of the analysis chains.

4,4′-[4,4′-Sulfonyl­bis­(p-phenyl­ene­oxy)]dibutanoic acid

PubMed Central

Fu, Chun-Yan; Liu, Yong-Hui; Zhou, Zhong-Liu; Tang, Hong

2011-01-01

In the title compound, C20H22O8S, the dihedral angle between the two benzene rings is 81.6 (3)°. The benzene-connected portions of the alk­oxy substituents are almost coplanar with their respective rings [C—C—O—C torsion angles of 174.77 (17) and −178.5 (4)°]. One of the butanoic acid groups is disordered over two conformations with a site-occupancy ratio 0.719 (6):0.281 (6). In the crystal, pairs of O—H⋯O hydrogen bonds link the mol­ecules into infinite zigzag chains along [130]. PMID:21754375

Thermodynamic study of quercetin and rutin mixtures with alcohols

NASA Astrophysics Data System (ADS)

Szymczyk, Katarzyna; Taraba, Anna

2018-04-01

The paper presents interactions between quercetin (3,3‧,4‧,5,7-pentahydroxyflavone) and its glycoside, rutin with short chain alcohols, methanol, ethanol and 1-propanol studied by the surface tension measurements. An attempt was made to investigate the effect of flavonoid and alcohol concentrations as well as temperature on the thermodynamic parameters of alcohols adsorption at the water-air interface that is the standard free enthalpy, enthalpy and entropy of adsorption as well as the infinite dilution activity coefficient. The obtained results show that the mixtures of quercetin with methanol and rutin with ethanol are characterized by the best adsorption properties but all studied systems become less structured after adsorption.

Recombination Processes and Nonlinear Markov Chains.

PubMed

Pirogov, Sergey; Rybko, Alexander; Kalinina, Anastasia; Gelfand, Mikhail

2016-09-01

Bacteria are known to exchange genetic information by horizontal gene transfer. Since the frequency of homologous recombination depends on the similarity between the recombining segments, several studies examined whether this could lead to the emergence of subspecies. Most of them simulated fixed-size Wright-Fisher populations, in which the genetic drift should be taken into account. Here, we use nonlinear Markov processes to describe a bacterial population evolving under mutation and recombination. We consider a population structure as a probability measure on the space of genomes. This approach implies the infinite population size limit, and thus, the genetic drift is not assumed. We prove that under these conditions, the emergence of subspecies is impossible.

Exact infinite-time statistics of the Loschmidt echo for a quantum quench.

PubMed

Campos Venuti, Lorenzo; Jacobson, N Tobias; Santra, Siddhartha; Zanardi, Paolo

2011-07-01

The equilibration dynamics of a closed quantum system is encoded in the long-time distribution function of generic observables. In this Letter we consider the Loschmidt echo generalized to finite temperature, and show that we can obtain an exact expression for its long-time distribution for a closed system described by a quantum XY chain following a sudden quench. In the thermodynamic limit the logarithm of the Loschmidt echo becomes normally distributed, whereas for small quenches in the opposite, quasicritical regime, the distribution function acquires a universal double-peaked form indicating poor equilibration. These findings, obtained by a central limit theorem-type result, extend to completely general models in the small-quench regime.

2-[4-(4,5-Dihydro-1H-pyrrol-2-yl)phen­yl]-4,5-dihydro-1H-imidazole

PubMed Central

Kia, Reza; Fun, Hoong-Kun; Kargar, Hadi

2008-01-01

The mol­ecule of the title compound, C12H14N4, lies about a crystallographic inversion centre. The five- and six-membered rings are twisted from each other, forming a dihedral angle of 18.06 (7)°. In the crystal structure, neighbouring mol­ecules are linked by inter­molecular N—H⋯N hydrogen bonds into one-dimensional infinite chains forming 18-membered rings with R 2 2(18) motifs. The crystal structure is further stabilized by weak inter­molecular π–π stacking [centroid–centroid distance = 3.8254 (6) Å] and C—H⋯π inter­actions. PMID:21581375

Baxter operators and Hamiltonians for "nearly all" integrable closed gl(n) spin chains

NASA Astrophysics Data System (ADS)

Frassek, Rouven; Łukowski, Tomasz; Meneghelli, Carlo; Staudacher, Matthias

2013-09-01

We continue our systematic construction of Baxter Q-operators for spin chains, which is based on certain degenerate solutions of the Yang-Baxter equation. Here we generalize our approach from the fundamental representation of gl(n) to generic finite-dimensional representations in quantum space. The results equally apply to non-compact representations of highest or lowest weight type. We furthermore fill an apparent gap in the literature, and provide the nearest-neighbor Hamiltonians of the spin chains in question for all cases where the gl(n) representations are described by rectangular Young diagrams, as well as for their infinite-dimensional generalizations. They take the form of digamma functions depending on operator-valued shifted weights. We believe that this condition follows from [R0,I,Jba]=0, [R0,I,Jb˙a˙]=0, [R0,I,Jbc˙Jc˙a]=0, which are specializations, respectively, of the last equation in (2.14), (2.16) and (2.19) in the case of minimal representations. Clearly R0,I can be considered as a function of the Casimir operators of gl(n) as well. These are just constants in a given irreducible representation and will not enter the discussion regarding the determination of R0,I.

Time-dependent real space RG on the spin-1/2 XXZ chain

NASA Astrophysics Data System (ADS)

Mason, Peter; Zagoskin, Alexandre; Betouras, Joseph

In order to measure the spread of information in a system of interacting fermions with nearest-neighbour couplings and strong bond disorder, one could utilise a dynamical real space renormalisation group (RG) approach on the spin-1/2 XXZ chain. Under such a procedure, a many-body localised state is established as an infinite randomness fixed point and the entropy scales with time as log(log(t)). One interesting further question that results from such a study is the case when the Hamiltonian explicitly depends on time. Here we answer this question by considering a dynamical renormalisation group treatment on the strongly disordered random spin-1/2 XXZ chain where the couplings are time-dependent and chosen to reflect a (slow) evolution of the governing Hamiltonian. Under the condition that the renormalisation process occurs at fixed time, a set of coupled second order, nonlinear PDE's can be written down in terms of the random distributions of the bonds and fields. Solution of these flow equations at the relevant critical fixed points leads us to establish the dynamics of the flow as we sweep through the quantum critical point of the Hamiltonian. We will present these critical flows as well as discussing the issues of duality, entropy and many-body localisation.

Synthesis, crystal structure, optical and thermal properties of lanthanide hydrogen-polyphosphates Ln[H(PO3)4] (Ln = Tb, Dy, Ho).

PubMed

Förg, Katharina; Höppe, Henning A

2015-11-28

Lanthanide hydrogen-polyphosphates Ln[H(PO3)4] (Ln = Tb, Dy, Ho) were synthesised as colourless (Ln = Tb, Dy) and light pink (Ln = Ho) crystalline powders by reaction of Tb4O7/Dy2O3/Ho2O3 with H3PO3 at 380 °C. All compounds crystallise isotypically (P2(1)/c (no. 14), Z = 4, a(Tb) = 1368.24(4) pm, b(Tb) = 710.42(2) pm, c(Tb) = 965.79(3) pm, β(Tb) = 101.200(1)°, 3112 data, 160 parameters, wR2 = 0.062, a(Ho) = 1363.34(5) pm, b(Ho) = 709.24(3) pm, c(Ho) = 959.07(4) pm, β(Ho) = 101.055(1)°, 1607 data, 158 parameters, wR2 = 0.058). The crystal structure comprises two different infinite helical chains of corner-sharing phosphate tetrahedra. In-between these chains the lanthanide ions are located, coordinated by seven oxygen atoms belonging to four different polyphosphate chains. Vibrational, UV/Vis and fluorescence spectra of Ln[H(PO3)4] (Ln = Tb, Dy, Ho) as well as Dy[H(PO3)4]:Ln (Ln = Ce, Eu) and the magnetic and thermal behaviour of Tb[H(PO3)4] are reported.

Allele Age Under Non-Classical Assumptions is Clarified by an Exact Computational Markov Chain Approach.

PubMed

De Sanctis, Bianca; Krukov, Ivan; de Koning, A P Jason

2017-09-19

Determination of the age of an allele based on its population frequency is a well-studied problem in population genetics, for which a variety of approximations have been proposed. We present a new result that, surprisingly, allows the expectation and variance of allele age to be computed exactly (within machine precision) for any finite absorbing Markov chain model in a matter of seconds. This approach makes none of the classical assumptions (e.g., weak selection, reversibility, infinite sites), exploits modern sparse linear algebra techniques, integrates over all sample paths, and is rapidly computable for Wright-Fisher populations up to N e  = 100,000. With this approach, we study the joint effect of recurrent mutation, dominance, and selection, and demonstrate new examples of "selective strolls" where the classical symmetry of allele age with respect to selection is violated by weakly selected alleles that are older than neutral alleles at the same frequency. We also show evidence for a strong age imbalance, where rare deleterious alleles are expected to be substantially older than advantageous alleles observed at the same frequency when population-scaled mutation rates are large. These results highlight the under-appreciated utility of computational methods for the direct analysis of Markov chain models in population genetics.

Supramolecular hydrogen-bonding networks in bis(adeninium) phthalate phthalic acid 1.45-hydrate.

PubMed

Sridhar, Balasubramanian; Ravikumar, Krishnan

2007-04-01

In the title compound, 2C(5)H(6)N(5)(+).C(8)H(4)O(4)(2-).C(8)H(6)O(4).1.45H(2)O, the asymmetric unit comprises two adeninium cations, two half phthalate anions with crystallographic C(2) symmetry, one neutral phthalic acid molecule, and one fully occupied and one partially occupied site (0.45) for water molecules. The adeninium cations form N-H...O hydrogen bonds with the phthalate anions. The cations also form infinite one-dimensional polymeric ribbons via N-H...N interactions. In the crystal packing, hydrogen-bonded columns of cations, anions and phthalate anions extend parallel to the c axis. The water molecules crosslink adjacent columns into hydrogen-bonded layers.

Controlling the Morphology of Side Chain Liquid Crystalline Block Copolymer Thin Films through Variations in Liquid Crystalline Content

PubMed Central

Verploegen, Eric; Zhang, Tejia; Jung, Yeon Sik; Ross, Caroline; Hammond, Paula T.

2009-01-01

In this paper we describe methods for manipulating the morphology of side-chain liquid crystalline block copolymers through variations in the liquid crystalline content. By systematically controlling the covalent attachment of side chain liquid crystals to a block copolymer (BCP) backbone, the morphology of both the liquid crystalline (LC) mesophase and the phase segregated BCP microstructures can be precisely manipulated. Increases in LC functionalization lead to stronger preferences for the anchoring of the LC mesophase relative to the substrate and the inter-material dividing surface (IMDS). By manipulating the strength of these interactions the arrangement and ordering of the ultrathin film block copolymer nanostructures can be controlled, yielding a range of morphologies that includes perpendicular and parallel cylinders, as well as both perpendicular and parallel lamellae. Additionally, we demonstrate the utilization of selective etching to create a nanoporous liquid crystalline polymer thin film. The unique control over the orientation and order of the self-assembled morphologies with respect to the substrate will allow for the custom design of thin films for specific nano-patterning applications without manipulation of the surface chemistry or the application of external fields. PMID:18763835

Synchronized Molecular-Dynamics simulation for thermal lubrication of a polymeric liquid between parallel plates

NASA Astrophysics Data System (ADS)

Yasuda, Shugo; Yamamoto, Ryoichi

2015-11-01

The Synchronized Molecular-Dynamics simulation which was recently proposed by authors is applied to the analysis of polymer lubrication between parallel plates. In the SMD method, the MD simulations are assigned to small fluid elements to calculate the local stresses and temperatures and are synchronized at certain time intervals to satisfy the macroscopic heat- and momentum-transport equations.The rheological properties and conformation of the polymer chains coupled with local viscous heating are investigated with a non-dimensional parameter, the Nahme-Griffith number, which is defined as the ratio of the viscous heating to the thermal conduction at the characteristic temperature required to sufficiently change the viscosity. The present simulation demonstrates that strong shear thinning and a transitional behavior of the conformation of the polymer chains are exhibited with a rapid temperature rise when the Nahme-Griffith number exceeds unity.The results also clarify that the reentrant transition of the linear stress-optical relation occurs for large shear stresses due to the coupling of the conformation of polymer chains with heat generation under shear flows. This study was financially supported by JSPS KAKENHI Grant Nos. 26790080 and 26247069.

Controlling the morphology of side chain liquid crystalline block copolymer thin films through variations in liquid crystalline content.

PubMed

Verploegen, Eric; Zhang, Tejia; Jung, Yeon Sik; Ross, Caroline; Hammond, Paula T

2008-10-01

In this paper, we describe methods for manipulating the morphology of side-chain liquid crystalline block copolymers through variations in the liquid crystalline content. By systematically controlling the covalent attachment of side chain liquid crystals to a block copolymer (BCP) backbone, the morphology of both the liquid crystalline (LC) mesophase and the phase-segregated BCP microstructures can be precisely manipulated. Increases in LC functionalization lead to stronger preferences for the anchoring of the LC mesophase relative to the substrate and the intermaterial dividing surface. By manipulating the strength of these interactions, the arrangement and ordering of the ultrathin film block copolymer nanostructures can be controlled, yielding a range of morphologies that includes perpendicular and parallel cylinders, as well as both perpendicular and parallel lamellae. Additionally, we demonstrate the utilization of selective etching to create a nanoporous liquid crystalline polymer thin film. The unique control over the orientation and order of the self-assembled morphologies with respect to the substrate will allow for the custom design of thin films for specific nanopatterning applications without manipulation of the surface chemistry or the application of external fields.

Universal Broadening of the Light Cone in Low-Temperature Transport

NASA Astrophysics Data System (ADS)

Bertini, Bruno; Piroli, Lorenzo; Calabrese, Pasquale

2018-04-01

We consider the low-temperature transport properties of critical one-dimensional systems that can be described, at equilibrium, by a Luttinger liquid. We focus on the prototypical setting where two semi-infinite chains are prepared in two thermal states at small but different temperatures and suddenly joined together. At large distances x and times t , conformal field theory characterizes the energy transport in terms of a single light cone spreading at the sound velocity v . Energy density and current take different constant values inside the light cone, on its left, and on its right, resulting in a three-step form of the corresponding profiles as a function of ζ =x /t . Here, using a nonlinear Luttinger liquid description, we show that for generic observables this picture is spoiled as soon as a nonlinearity in the spectrum is present. In correspondence of the transition points x /t =±v , a novel universal region emerges at infinite times, whose width is proportional to the temperatures on the two sides. In this region, expectation values have a different temperature dependence and show smooth peaks as a function of ζ . We explicitly compute the universal function describing such peaks. In the specific case of interacting integrable models, our predictions are analytically recovered by the generalized hydrodynamic approach.

Zirconium tetrachloride revisited

DOE PAGES

Borjas Nevarez, Rosendo; Balasekaran, Samundeeswari Mariappan; Kim, Eunja; ...

2018-02-19

We present that zirconium tetrachloride, ZrCl 4, is a strategic material with wide-ranging applications. Until now, only one crystallographic study on ZrCl 4has been reported [Krebs (1970).Z. Anorg. Allg. Chem.378, 263–272] and that was more than 40 years ago. The compound used for the previous determination was prepared from ZrO 2 and Cl 2–CCl 4, and single-crystal X-ray diffraction (SCXRD) studies on ZrCl 4 obtained from Zr metal have not yet been reported. In this context, we prepared ZrCl 4 from the reaction of Zr metal and Cl 2 gas in a sealed tube and investigated its structure at 100,more » 150, 200, 250, and 300 K. At 300 K, the SCXRD analysis indicates that ZrCl 4 crystallizes in the orthorhombic space group Pca2 1 [a= 6.262 (9),b= 7.402 (11),c= 12.039 (17) Å, andV= 558.0 (14) Å 3] and consists of infinite zigzag chains of edge-sharing ZrCl 6 octahedra. This chain motif is similar to that observed previously in ZrCl 4, but the structural parameters and space group differ. Finally, in the temperature range 100–300 K, no phase transformation was identified, while elongation of intra-chain Zr...Zr [3.950 (1) Å at 100 K and 3.968 (5) Å at 300 K] and inter-chain Cl...Cl [3.630 (3) Å at 100 K and 3.687 (9) Å at 300 K] distances occurred.« less

Negativity as the entanglement measure to probe the Kondo regime in the spin-chain Kondo model

NASA Astrophysics Data System (ADS)

Bayat, Abolfazl; Sodano, Pasquale; Bose, Sougato

2010-02-01

We study the entanglement of an impurity at one end of a spin chain with a block of spins using negativity as a true measure of entanglement to characterize the unique features of the gapless Kondo regime in the spin-chain Kondo model. For this spin chain in the Kondo regime we determine—with a true entanglement measure—the spatial extent of the Kondo screening cloud, we propose an ansatz for its ground state and demonstrate that the impurity spin is indeed maximally entangled with the cloud. To better evidence the peculiarities of the Kondo regime, we carry a parallel analysis of the entanglement properties of the Kondo spin-chain model in the gapped dimerized regime. Our study shows how a genuine entanglement measure stemming from quantum information theory can fully characterize also nonperturbative regimes accessible to certain condensed matter systems.

Individuals' knowledge and practices of the cold chain.

PubMed

Uçar, Aslı; Ozçelik, Ayşe Özfer

2013-01-01

This study aims to identify the influence of education on the practices and knowledge of consumers to protect or maintain the cold chain in the Turkish capital of Ankara. Data were gathered by using a questionnaire. Participants were 700 randomly selected volunteering adults. The majority of the participants had a university degree (69.0%) and did not know the definition of cold chain but had some knowledge about it, and differences existed between primary school and university graduates. The scores of consumers' attitudes to maintain cold chain were determined to increase in parallel with education level. The rate of people knowing refrigerator temperature, the coldest part of refrigerator, and controlling whether shops correctly store the products was highest in university graduates. Adults were observed to believe that shop assistants were responsible for maintaining a cold chain. However, the actual importance of consumers in this process reveals the importance of education for individuals.

Human disease mortality kinetics are explored through a chain model embodying principles of extreme value theory and competing risks.

PubMed

Juckett, D A; Rosenberg, B

1992-04-21

The distributions for human disease-specific mortality exhibit two striking characteristics: survivorship curves that intersect near the longevity limit; and, the clustering of best-fitting Weibull shape parameter values into groups centered on integers. Correspondingly, we have hypothesized that the distribution intersections result from either competitive processes or population partitioning and the integral clustering in the shape parameter results from the occurrence of a small number of rare, rate-limiting events in disease progression. In this report we initiate a theoretical examination of these questions by exploring serial chain model dynamics and parameteric competing risks theory. The links in our chain models are composed of more than one bond, where the number of bonds in a link are denoted the link size and are the number of events necessary to break the link and, hence, the chain. We explored chains with all links of the same size or with segments of the chain composed of different size links (competition). Simulations showed that chain breakage dynamics depended on the weakest-link principle and followed kinetics of extreme-values which were very similar to human mortality kinetics. In particular, failure distributions for simple chains were Weibull-type extreme-value distributions with shape parameter values that were identifiable with the integral link size in the limit of infinite chain length. Furthermore, for chains composed of several segments of differing link size, the survival distributions for the various segments converged at a point in the S(t) tails indistinguishable from human data. This was also predicted by parameteric competing risks theory using Weibull underlying distributions. In both the competitive chain simulations and the parametric competing risks theory, however, the shape values for the intersecting distributions deviated from the integer values typical of human data. We conclude that rare events can be the source of integral shapes in human mortality, that convergence is a salient feature of multiple endpoints, but that pure competition may not be the best explanation for the exact type of convergence observable in human mortality. Finally, while the chain models were not motivated by any specific biological structures, interesting biological correlates to them may be useful in gerontological research.

Methanesulfonates of high-valent metals: syntheses and structural features of MoO2(CH3SO3)2, UO2(CH3SO3)2, ReO3(CH3SO3), VO(CH3SO3)2, and V2O3(CH3SO3)4 and their thermal decomposition under N2 and O2 atmosphere.

PubMed

Betke, Ulf; Neuschulz, Kai; Wickleder, Mathias S

2011-11-04

Oxide methanesulfonates of Mo, U, Re, and V have been prepared by reaction of MoO(3), UO(2)(CH(3)COO)(2)·2H(2)O, Re(2)O(7)(H(2)O)(2), and V(2)O(5) with CH(3)SO(3)H or mixtures thereof with its anhydride. These compounds are the first examples of solvent-free oxide methanesulfonates of these elements. MoO(2)(CH(3)SO(3))(2) (Pbca, a=1487.05(4), b=752.55(2), c=1549.61(5) pm, V=1.73414(9) nm(3), Z=8) contains [MoO(2)] moieties connected by [CH(3)SO(3)] ions to form layers parallel to (100). UO(2)(CH(3)SO(3))(2) (P2(1)/c, a=1320.4(1), b=1014.41(6), c=1533.7(1) pm, β=112.80(1)°, V=1.8937(3) nm(3), Z=8) consists of linear UO(2)(2+) ions coordinated by five [CH(3)SO(3)] ions, forming a layer structure. VO(CH(3)SO(3))(2) (P2(1)/c, a=1136.5(1), b=869.87(7), c=915.5(1) pm, β=113.66(1)°, V=0.8290(2) nm(3), Z=4) contains [VO] units connected by methanesulfonate anions to form corrugated layers parallel to (100). In ReO(3)(CH(3)SO(3)) (P1, a=574.0(1), b=1279.6(3), c=1641.9(3) pm, α=102.08(2), β=96.11(2), γ=99.04(2)°, V=1.1523(4) nm(3), Z=8) a chain structure exhibiting infinite O-[ReO(2)]-O-[ReO(2)]-O chains is formed. Each [ReO(2)]-O-[ReO(2)] unit is coordinated by two bidentate [CH(3)SO(3)] ions. V(2)O(3)(CH(3)SO(3))(4) (I2/a, a=1645.2(3), b=583.1(1), c=1670.2(3) pm, β=102.58(3), V=1.5637(5) pm(3), Z=4) adopts a chain structure, too, but contains discrete [VO]-O-[VO] moieties, each coordinated by two bidentate [CH(3)SO(3)] ligands. Additional methanesulfonate ions connect the [V(2)O(3)] groups along [001]. Thermal decomposition of the compounds was monitored under N(2) and O(2) atmosphere by thermogravimetric/differential thermal analysis and XRD measurements. Under N(2) the decomposition proceeds with reduction of the metal leading to the oxides MoO(2), U(3)O(7), V(4)O(7), and VO(2); for MoO(2)(CH(3)SO(3))(2), a small amount of MoS(2) is formed. If the thermal decomposition is carried out in a atmosphere of O(2) the oxides MoO(3) and V(2)O(5) are formed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

catena-Poly[[[4,6-bis­(2-pyrid­yl)-1,3,5-triazin-2-olato]copper(II)]-μ-chlorido

PubMed Central

Cao, Man-Li

2011-01-01

The title compound, [Cu(C13H8N5O)Cl]n, has a chain structure parallel to [100] with Cu2+ cations in a trigonal–bipyramidal coordination environment. The ligand adopts a tridentate tripyridyl coordination mode and a chloride ion acts as a bridge. The chains are linked via weak C—H⋯O and C—H⋯Cl hydrogen bonds into a three-dimensional supra­molecular network. PMID:21754632

Sentinel-1 data massive processing for large scale DInSAR analyses within Cloud Computing environments through the P-SBAS approach

NASA Astrophysics Data System (ADS)

Lanari, Riccardo; Bonano, Manuela; Buonanno, Sabatino; Casu, Francesco; De Luca, Claudio; Fusco, Adele; Manunta, Michele; Manzo, Mariarosaria; Pepe, Antonio; Zinno, Ivana

2017-04-01

The SENTINEL-1 (S1) mission is designed to provide operational capability for continuous mapping of the Earth thanks to its two polar-orbiting satellites (SENTINEL-1A and B) performing C-band synthetic aperture radar (SAR) imaging. It is, indeed, characterized by enhanced revisit frequency, coverage and reliability for operational services and applications requiring long SAR data time series. Moreover, SENTINEL-1 is specifically oriented to interferometry applications with stringent requirements based on attitude and orbit accuracy and it is intrinsically characterized by small spatial and temporal baselines. Consequently, SENTINEL-1 data are particularly suitable to be exploited through advanced interferometric techniques such as the well-known DInSAR algorithm referred to as Small BAseline Subset (SBAS), which allows the generation of deformation time series and displacement velocity maps. In this work we present an advanced interferometric processing chain, based on the Parallel SBAS (P-SBAS) approach, for the massive processing of S1 Interferometric Wide Swath (IWS) data aimed at generating deformation time series in efficient, automatic and systematic way. Such a DInSAR chain is designed to exploit distributed computing infrastructures, and more specifically Cloud Computing environments, to properly deal with the storage and the processing of huge S1 datasets. In particular, since S1 IWS data are acquired with the innovative Terrain Observation with Progressive Scans (TOPS) mode, we could benefit from the structure of S1 data, which are composed by bursts that can be considered as separate acquisitions. Indeed, the processing is intrinsically parallelizable with respect to such independent input data and therefore we basically exploited this coarse granularity parallelization strategy in the majority of the steps of the SBAS processing chain. Moreover, we also implemented more sophisticated parallelization approaches, exploiting both multi-node and multi-core programming techniques. Currently, Cloud Computing environments make available large collections of computing resources and storage that can be effectively exploited through the presented S1 P-SBAS processing chain to carry out interferometric analyses at a very large scale, in reduced time. This allows us to deal also with the problems connected to the use of S1 P-SBAS chain in operational contexts, related to hazard monitoring and risk prevention and mitigation, where handling large amounts of data represents a challenging task. As a significant experimental result we performed a large spatial scale SBAS analysis relevant to the Central and Southern Italy by exploiting the Amazon Web Services Cloud Computing platform. In particular, we processed in parallel 300 S1 acquisitions covering the Italian peninsula from Lazio to Sicily through the presented S1 P-SBAS processing chain, generating 710 interferograms, thus finally obtaining the displacement time series of the whole processed area. This work has been partially supported by the CNR-DPC agreement, the H2020 EPOS-IP project (GA 676564) and the ESA GEP project.

Liquid crystalline polymers in good nematic solvents: Free chains, mushrooms, and brushes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, D.R.M.; Halperin, A.

1993-08-02

The swelling of main chain liquid crystalline polymers (LCPs) in good nematic solvents is theoretically studied, focusing on brushes of terminally anchored, grafted LCPs. The analysis is concerned with long LCPs, of length L, with n[sub 0] >> 1 hairpin defects. The extension behavior of the major axis, R[parallel], of these ellipsoidal objects gives rise to an Ising elasticity with a free energy penalty of F[sub el](R[parallel])/kT [approx] n[sub 0] [minus] n[sub 0](1 [minus] R[parallel][sup 2]/L[sup 2])[sup 1/2]. The theory of the extension behavior enables the formulation of a Flory type theory of swelling of isolated LCPs yielding R[parallel] [approx]more » exp(2U[sub h]/5kT)N[sup 3/5] and R [perpendicular] [approx] exp([minus]U[sub h]/10kT)N[sup 3/5], with N the degree of polymerization and U[sub h] the hairpin energy. It also allows the generalization of the Alexander model for polymer brushes to the case of grafted LCPs. The behavior of LCP brushes depends on the alignment imposed by the grafting surface and the liquid crystalline solvent. A tilting phase transition is predicted as the grafting density is increased for a surface imposing homogeneous, parallel anchoring. A related transition is expected upon compression of a brush subject to homeotropic, perpendicular alignment. The effect of magnetic or electric fields on these phase transitions is also studied. The critical magnetic/electric field for the Frederiks transition can be lowered to arbitrarily small values by using surfaces coated by brushes of appropriate density.« less

Comparison principle for impulsive functional differential equations with infinite delays and applications

NASA Astrophysics Data System (ADS)

Li, Xiaodi; Shen, Jianhua; Akca, Haydar; Rakkiyappan, R.

2018-04-01

We introduce the Razumikhin technique to comparison principle and establish some comparison results for impulsive functional differential equations (IFDEs) with infinite delays, where the infinite delays may be infinite time-varying delays or infinite distributed delays. The idea is, under the help of Razumikhin technique, to reduce the study of IFDEs with infinite delays to the study of scalar impulsive differential equations (IDEs) in which the solutions are easy to deal with. Based on the comparison principle, we study the qualitative properties of IFDEs with infinite delays , which include stability, asymptotic stability, exponential stability, practical stability, boundedness, etc. It should be mentioned that the developed results in this paper can be applied to IFDEs with not only infinite delays but also persistent impulsive perturbations. Moreover, even for the special cases of non-impulsive effects or/and finite delays, the criteria prove to be simpler and less conservative than some existing results. Finally, two examples are given to illustrate the effectiveness and advantages of the proposed results.

Two series of reactant's ratio-dependent lanthanide organic frameworks derived from nicotinic acid N-oxide and oxalate: synthesis, crystal structures and luminescence properties.

PubMed

Yu, Yanyan; Zhang, Lijuan; Zhou, Yunshan; Zuhra, Zareen

2015-03-14

Two series of lanthanide(III)–organic frameworks with the molecular formula [Ln2(NNO)2(OX)2(H2O)4]n (Ln = Eu 1, Tb 2, Sm 3, Dy 4, Gd 5) and [Ln2(NNO)4(OX)(H2O)2]n (Ln = Eu 6, Tb 7, Sm 8, Dy 9, Gd 10) were synthesized successfully under the same hydrothermal conditions with nicotinic N-oxide (HNNO) and oxalic acid (H2OX) as the mixed ligands merely through varying the molar ratio of the reactants. The compounds were characterized by IR, elemental analysis, UV, TG-DTA and powder X-ray diffraction (XRD). X-ray single-crystal diffraction analyses of compounds 1 and 7 selected as representatives and powder XRD analysis of the compounds revealed that both the series of compounds feature three-dimensional (3-D) open frameworks, and crystallize in the triclinic P1 space group while with different unit cell parameters. In compound 1, pairs of Eu(3+) ions and pairs of NNO(−) ligands connect with each other alternately to form a 1-D infinite Eu-NNO double chain, the adjacent 1-D double-chains are then joined together through OX(2−) ligands leading to a 2D layer, the 2-D layers are further ‘pillared’ by OX(2−) ligands resulting in a 3-D framework. In compound 7, the 1-D Tb-NNO infinite chain and its 2-D layer are formed in an almost similar fashion to that in compound 1. The difference between the structures of the two compounds 1 and 7 is that the adjacent 2-D layers in compound 7 are further connected by NNO(−) ligands resulting in a 3-D framework. The photoluminescence properties and energy transfer mechanism of the compounds were studied systematically. The energy level of the lowest triplet states of the HNNO ligand (23148 cm(−1)) was determined based on the phosphorescence spectrum of compound 5 at 77 K. The (5)D0 (Eu(3+)) and (5)D4 (Tb(3+)) emission lifetimes are 0.46 ms, 0.83 ms, 0.69 ms and 0.89 ms and overall quantum yields are 1.03%, 3.29%, 2.58% and 3.78% for the compounds 1, 2, 6 and 7, respectively.

Fast dynamic electron transfer along infinite anion-cation chains in technetium and rhenium acido clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antipov, B.G.; Kryuchkov, S.V.; Grigor`ev, M.S.

1995-09-01

New technetium and rhenium compounds with ferricenium cations - [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 3}[Tc{sub 6}I{sub 14}], [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 3}[Tc{sub 6}Cl{sub 14}], [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 2}[Tc{sub 8}Br{sub 14}], and [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 2}[Re{sub 2}Br{sub 8}] - are synthesized and identified. The compounds are characterized by the methods of static magnetic susceptibility and differential scanning calorimetry; solid-state conductivity measurements; and IR, EPR, {sup 57}Fe Moessbauer, and X-ray photoelectron spectroscopic data. These data are compared with the physicochemical characteristics of ferricenium pertechnetate and hexachlorotechnetate, as well as of a number of reference technetium and rhenium compounds containing the samemore » anions but different cations. The structure of [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 3}[Tc{sub 6}I{sub 14}] is determined by X-ray diffraction analysis of a single crystal [space group P6/m, a = 15.34(2), c = 12.70(1) {angstrom}]. The structures of the remaining compounds were confirmed by comparing their spectroscopic properties with corresponding properties of compounds with known composition and structure. None of the compounds with ferricenium cations exhibit covalent or other localized bonds between anions and cations. However, the physicochemical properties of these compounds indicate the occurrence of a fast dynamic electron transfer along infinite anion-cation chains. Compounds [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 3}[Tc{sub 6}Cl{sub 14}] and [Fe(C{sub 5}H{sub 5}){sub 2}]{sub 2}[Tc{sub 8}Br{sub 14}] were found to exhibit a new phenomenon of X-ray-induced low-temper ature high-energy electron emission.« less

On Kronecker-Capelli type theorems for infinite systems

NASA Astrophysics Data System (ADS)

Fedorov, Foma M.; Potapova, Sargylana V.

2017-11-01

On the basis of the new concept of the decrement of an infinite matrices and determinants, we studied the inconsistency of a general infinite systems of linear algebraic equations. We proved the theorem on inconsistency of a infinite system when the decrement of its matrix is nonzero.

Structural considerations for functional anti-EGFR × anti-CD3 bispecific diabodies in light of domain order and binding affinity.

PubMed

Asano, Ryutaro; Nagai, Keisuke; Makabe, Koki; Takahashi, Kento; Kumagai, Takashi; Kawaguchi, Hiroko; Ogata, Hiromi; Arai, Kyoko; Umetsu, Mitsuo; Kumagai, Izumi

2018-03-02

We previously reported a functional humanized bispecific diabody (bsDb) that targeted EGFR and CD3 (hEx3-Db) and enhancement of its cytotoxicity by rearranging the domain order in the V domain. Here, we further dissected the effect of domain order in bsDbs on their cross-linking ability and binding kinetics to elucidate general rules regarding the design of functional bsDbs. Using Ex3-Db as a model system, we first classified the four possible domain orders as anti-parallel (where both chimeric single-chain components are variable heavy domain (VH)-variable light domain (VL) or VL-VH order) and parallel types (both chimeric single-chain components are mixed with VH-VL and VL-VH order). Although anti-parallel Ex3-Dbs could cross-link the soluble target antigens, their cross-linking ability between soluble targets had no correlation with their growth inhibitory effects. In contrast, the binding affinity of one of the two constructs with a parallel-arrangement V domain was particularly low, and structural modeling supported this phenomenon. Similar results were observed with E2x3-Dbs, in which the V region of the anti-EGFR antibody clone in hEx3 was replaced with that of another anti-EGFR clone. Only anti-parallel types showed affinity-dependent cancer inhibitory effects in each molecule, and E2x3-LH (both components in VL-VH order) showed the most intense anti-tumor activity in vitro and in vivo . Our results showed that, in addition to rearranging the domain order of bsDbs, increasing their binding affinity may be an ideal strategy for enhancing the cytotoxicity of anti-parallel constructs and that E2x3-LH is particularly attractive as a candidate next-generation anti-cancer drug.

Influence of movement direction on levitation performance and energy dissipation in a superconducting maglev system

NASA Astrophysics Data System (ADS)

Huang, Chen-Guang; Yong, Hua-Dong; Zhou, You-He

2017-11-01

During the regular operation of a maglev system, the superconducting levitation body may move away from the working position due to the external disturbance and the curved part of the guideway. Based on the A - V formulation of magnetoquasistatic Maxwell's equations, in this paper, a two-dimensional numerical model is applied to study the influence of movement direction on a typical maglev system consisting of an infinitely long high-temperature superconductor and a guideway of two infinitely long parallel permanent magnets with opposite horizontal magnetization. After the highly nonlinear current-voltage characteristic of the superconductor is taken into account, the levitation performance change and the energy dissipation induced by the relative movement of the superconductor and the guideway are discussed. The results show that the levitation force, guidance force and power loss are strongly dependent on the movement direction and speed of the superconductor when it moves away from the working position. If the superconductor moves periodically through the working position, these three physical quantities will change periodically with time. Interestingly, the power loss drastically increases during the first cycle, and after the first cycle it starts to decrease and finally tends to a dynamic steady state. Moreover, an increase in the tilt angle of movement direction will improve the maximum levitation force and, simultaneously, enhance the energy dissipation of the maglev system.

Sound radiated by the interaction of non-homogeneous turbulence on a transversely sheared flow with leading and trailing edges of semi-infinite flat plate

NASA Astrophysics Data System (ADS)

Afsar, Mohammed; Sassanis, Vasilis

2017-11-01

The small amplitude unsteady motion on a transversely sheared mean flow is determined by two arbitrary convected quantities with a particular choice of gauge in which the Fourier transform of the pressure is linearly-related to a scalar potential whose integral solution can be written in terms of one of these convected quantities. This formulation becomes very useful for studying Rapid-distortion theory problems involving solid surface interaction. Recent work by Goldstein et al. (JFM, 2017) has shown that the convected quantities are related to the turbulence by exact conservation laws, which allow the upstream boundary conditions for interaction of a turbulent shear flow with a solid-surface (for example) to be derived self-consistently with appropriate asymptotic separation of scales. This result requires the imposition of causality on an intermediate variable within the conservation laws that represents the local particle displacement. In this talk, we use the model derived in Goldstein et al. for trailing edge noise and compare it to leading edge noise on a semi-infinite flat plate positioned parallel to the level curves of the mean flow. Since the latter represents the leading order solution for the aerofoil interaction problem, these results are expected to be generic. M.Z.A. would also like to thank Strathclyde University for financial support from the Chancellor's Fellowship.

Spin and topological order in a periodically driven spin chain

NASA Astrophysics Data System (ADS)

Russomanno, Angelo; Friedman, Bat-el; Dalla Torre, Emanuele G.

2017-07-01

The periodically driven quantum Ising chain has recently attracted a large attention in the context of Floquet engineering. In addition to the common paramagnet and ferromagnet, this driven model can give rise to new topological phases. In this work, we systematically explore its quantum phase diagram by examining the properties of its Floquet ground state. We specifically focus on driving protocols with time-reversal invariant points, and demonstrate the existence of an infinite number of distinct phases. These phases are separated by second-order quantum phase transitions, accompanied by continuous changes of local and string order parameters, as well as sudden changes of a topological winding number and of the number of protected edge states. When one of these phase transitions is adiabatically crossed, the correlator associated to the order parameter is nonvanishing over a length scale which shows a Kibble-Zurek scaling. In some phases, the Floquet ground state spontaneously breaks the discrete time-translation symmetry of the Hamiltonian. Our findings provide a better understanding of topological phases in periodically driven clean integrable models.

Multicast Delayed Authentication For Streaming Synchrophasor Data in the Smart Grid

PubMed Central

Câmara, Sérgio; Anand, Dhananjay; Pillitteri, Victoria; Carmo, Luiz

2017-01-01

Multicast authentication of synchrophasor data is challenging due to the design requirements of Smart Grid monitoring systems such as low security overhead, tolerance of lossy networks, time-criticality and high data rates. In this work, we propose inf -TESLA, Infinite Timed Efficient Stream Loss-tolerant Authentication, a multicast delayed authentication protocol for communication links used to stream synchrophasor data for wide area control of electric power networks. Our approach is based on the authentication protocol TESLA but is augmented to accommodate high frequency transmissions of unbounded length. inf TESLA protocol utilizes the Dual Offset Key Chains mechanism to reduce authentication delay and computational cost associated with key chain commitment. We provide a description of the mechanism using two different modes for disclosing keys and demonstrate its security against a man-in-the-middle attack attempt. We compare our approach against the TESLA protocol in a 2-day simulation scenario, showing a reduction of 15.82% and 47.29% in computational cost, sender and receiver respectively, and a cumulative reduction in the communication overhead. PMID:28736582

Bilinear forms and soliton solutions for a fourth-order variable-coefficient nonlinear Schrödinger equation in an inhomogeneous Heisenberg ferromagnetic spin chain or an alpha helical protein

NASA Astrophysics Data System (ADS)

Yang, Jin-Wei; Gao, Yi-Tian; Wang, Qi-Min; Su, Chuan-Qi; Feng, Yu-Jie; Yu, Xin

2016-01-01

In this paper, a fourth-order variable-coefficient nonlinear Schrödinger equation is studied, which might describe a one-dimensional continuum anisotropic Heisenberg ferromagnetic spin chain with the octuple-dipole interaction or an alpha helical protein with higher-order excitations and interactions under continuum approximation. With the aid of auxiliary function, we derive the bilinear forms and corresponding constraints on the variable coefficients. Via the symbolic computation, we obtain the Lax pair, infinitely many conservation laws, one-, two- and three-soliton solutions. We discuss the influence of the variable coefficients on the solitons. With different choices of the variable coefficients, we obtain the parabolic, cubic, and periodic solitons, respectively. We analyse the head-on and overtaking interactions between/among the two and three solitons. Interactions between a bound state and a single soliton are displayed with different choices of variable coefficients. We also derive the quasi-periodic formulae for the three cases of the bound states.

Self-assembly of [Pt(3n)(CO)(6n)]2- (n = 4-8) carbonyl clusters: from molecules to conducting molecular metal wires.

PubMed

Femoni, Cristina; Iapalucci, Maria Carmela; Longoni, Giuliano; Lovato, Tatiana; Stagni, Stefano; Zacchini, Stefano

2010-07-05

A comprehensive study discussing the different parameters that influence the self-assembly of [Pt(3n)(CO)(6n)](2-) (n = 4-8) clusters with miscellaneous mono- and dications into 0-D, 1-D, 2-D, and 3-D materials is herein reported. As an unexpected bonus, the use of Ru(II) dications allowed the first structural characterization of the previously unknown [Pt(21)(CO)(42)](2-) dianion. 0-D structures, which contain isolated ions, are electrical insulators in solid form. Conversely, as soon as infinite chains of clusters are formed, the electrical resistivity, measured in pressed pellets, decreases to 10(5)-10(6), 10(4), and 10(2) ohms cm for discontinuous, semicontinuous, and continuous chains, respectively. Therefore, the resemblance of these materials to molecular metal wires is not only morphological but also functional. Preliminary results of possible self-assembly phenomena in a solution of [Pt(15)(CO)(30)](2-) and [Pt(18)(CO)(36)](2-) according to dynamic light scattering experiments are also reported.

Concentrated Solutions of Single-Chain Nanoparticles: A Simple Model for Intrinsically Disordered Proteins under Crowding Conditions.

PubMed

Moreno, Angel J; Lo Verso, Federica; Arbe, Arantxa; Pomposo, José A; Colmenero, Juan

2016-03-03

By means of large-scale computer simulations and small-angle neutron scattering (SANS), we investigate solutions of single-chain nanoparticles (SCNPs), covering the whole concentration range from infinite dilution to melt density. The analysis of the conformational properties of the SCNPs reveals that these synthetic nano-objects share basic ingredients with intrinsically disordered proteins (IDPs), as topological polydispersity, generally sparse conformations, and locally compact domains. We investigate the role of the architecture of the SCNPs in their collapse behavior under macromolecular crowding. Unlike in the case of linear macromolecules, which experience the usual transition from self-avoiding to Gaussian random-walk conformations, crowding leads to collapsed conformations of SCNPs resembling those of crumpled globules. This behavior is already found at volume fractions (about 30%) that are characteristic of crowding in cellular environments. The simulation results are confirmed by the SANS experiments. Our results for SCNPs--a model system free of specific interactions--propose a general scenario for the effect of steric crowding on IDPs: collapse from sparse conformations at high dilution to crumpled globular conformations in cell environments.

Multicast Delayed Authentication For Streaming Synchrophasor Data in the Smart Grid.

PubMed

Câmara, Sérgio; Anand, Dhananjay; Pillitteri, Victoria; Carmo, Luiz

2016-01-01

Multicast authentication of synchrophasor data is challenging due to the design requirements of Smart Grid monitoring systems such as low security overhead, tolerance of lossy networks, time-criticality and high data rates. In this work, we propose inf -TESLA, Infinite Timed Efficient Stream Loss-tolerant Authentication, a multicast delayed authentication protocol for communication links used to stream synchrophasor data for wide area control of electric power networks. Our approach is based on the authentication protocol TESLA but is augmented to accommodate high frequency transmissions of unbounded length. inf TESLA protocol utilizes the Dual Offset Key Chains mechanism to reduce authentication delay and computational cost associated with key chain commitment. We provide a description of the mechanism using two different modes for disclosing keys and demonstrate its security against a man-in-the-middle attack attempt. We compare our approach against the TESLA protocol in a 2-day simulation scenario, showing a reduction of 15.82% and 47.29% in computational cost, sender and receiver respectively, and a cumulative reduction in the communication overhead.

Quasiparticle energies and lifetimes in a metallic chain model of a tunnel junction.

PubMed

Szepieniec, Mark; Yeriskin, Irene; Greer, J C

2013-04-14

As electronics devices scale to sub-10 nm lengths, the distinction between "device" and "electrodes" becomes blurred. Here, we study a simple model of a molecular tunnel junction, consisting of an atomic gold chain partitioned into left and right electrodes, and a central "molecule." Using a complex absorbing potential, we are able to reproduce the single-particle energy levels of the device region including a description of the effects of the semi-infinite electrodes. We then use the method of configuration interaction to explore the effect of correlations on the system's quasiparticle peaks. We find that when excitations on the leads are excluded, the device's highest occupied molecular orbital and lowest unoccupied molecular orbital quasiparticle states when including correlation are bracketed by their respective values in the Hartree-Fock (Koopmans) and ΔSCF approximations. In contrast, when excitations on the leads are included, the bracketing property no longer holds, and both the positions and the lifetimes of the quasiparticle levels change considerably, indicating that the combined effect of coupling and correlation is to alter the quasiparticle spectrum significantly relative to an isolated molecule.

Critical effects of alkyl chain length on fibril structures in benzene-trans(RR)- or (SS)-N,N'-alkanoyl-1,2-diaminocyclohexane gels.

PubMed

Sato, Hisako; Nakae, Takahiro; Morimoto, Kazuya; Tamura, Kenji

2012-02-28

Vibrational circular dichroism (VCD) spectra were recorded on benzene-d(6) gels formed by chiral low molecular mass gelators (LMGs), trans(RR)- or trans(SS)-N,N'-alkanoyl-1,2-diaminocyclohexane (denoted by RR-C(n) or SS-C(n), respectively; n = the number of carbon atoms in an introduced alkanoyl group). Attention was focused on the effects of alkyl chain length on the structures of the gels. When n was changed from 6 to 12, the signs of the coupled peaks around 1550 cm(-1) in the VCD spectra, which were assigned to the symmetric and asymmetric C=O stretching vibrations from the higher to lower wavenumber, respectively, critically depended on the alkyl chain length. In the case of RR-C(n), for example, the signs of the couplet were plus and minus for n = 8, 9, 10 and 12, while the signs of the same couplet were reversed for n = 6 and 7. The conformations of LMGs in fibrils were determined by comparing the observed IR and VCD spectra with those calculated for a monomeric molecule. The observed reversal of signs in the C=O couplet was rationalized in terms of the different modes of hydrogen bonding. In the case of C(8), C(9), C(10) and C(12), gelator molecules were stacked with their cyclohexyl rings in parallel, forming double anti-parallel chains of intermolecular hydrogen bonds using two pairs of >NH and >C=O groups. In case of C(6) and C(7), gelator molecules were stacked through a single chain of intermolecular hydrogen bonds using a pair of >NH and >C=O groups. The remaining pair of >NH and >C=O groups formed an intramolecular hydrogen bond.

Modality, Infinitives, and Finite Bare Verbs in Dutch and English Child Language

ERIC Educational Resources Information Center

Blom, Elma

2007-01-01

This article focuses on the meaning of nonfinite clauses ("root infinitives") in Dutch and English child language. I present experimental and naturalistic data confirming the claim that Dutch root infinitives are more often modal than English root infinitives. This cross-linguistic difference is significantly smaller than previously assumed,…

1H-Indole-3-carbaldehyde.

PubMed

Dileep, C S; Abdoh, M M M; Chakravarthy, M P; Mohana, K N; Sridhar, M A

2012-11-01

In the title compound, C(9)H(7)NO, the benzene ring forms a dihedral angle of 3.98 (12)° with the pyrrole ring. In the crystal, N-H⋯O hydrogen bonds links the mol-ecules into chains which run parallel to [02-1].

Raising the PT -transition threshold by strong coupling to neutral chains

NASA Astrophysics Data System (ADS)

Agarwal, Kaustubh S.; Pathak, Rajeev K.; Joglekar, Yogesh N.

2018-04-01

The PT -symmetry-breaking threshold in discrete realizations of systems with balanced gain and loss is determined by the effective coupling between the gain and loss sites. In one-dimensional chains, this threshold is maximum when the two sites are closest to each other or the farthest. We investigate the fate of this threshold in the presence of parallel, strongly coupled, Hermitian (neutral) chains and find that it is increased by a factor proportional to the number of neutral chains. We present numerical results and analytical arguments for this enhancement. We then consider the effects of adding neutral sites to PT -symmetric dimer and trimer configurations and show that the threshold is more than doubled, or tripled by their presence. Our results provide a surprising way to engineer the PT threshold in experimentally accessible samples.

Scalable L-infinite coding of meshes.

PubMed

Munteanu, Adrian; Cernea, Dan C; Alecu, Alin; Cornelis, Jan; Schelkens, Peter

2010-01-01

The paper investigates the novel concept of local-error control in mesh geometry encoding. In contrast to traditional mesh-coding systems that use the mean-square error as target distortion metric, this paper proposes a new L-infinite mesh-coding approach, for which the target distortion metric is the L-infinite distortion. In this context, a novel wavelet-based L-infinite-constrained coding approach for meshes is proposed, which ensures that the maximum error between the vertex positions in the original and decoded meshes is lower than a given upper bound. Furthermore, the proposed system achieves scalability in L-infinite sense, that is, any decoding of the input stream will correspond to a perfectly predictable L-infinite distortion upper bound. An instantiation of the proposed L-infinite-coding approach is demonstrated for MESHGRID, which is a scalable 3D object encoding system, part of MPEG-4 AFX. In this context, the advantages of scalable L-infinite coding over L-2-oriented coding are experimentally demonstrated. One concludes that the proposed L-infinite mesh-coding approach guarantees an upper bound on the local error in the decoded mesh, it enables a fast real-time implementation of the rate allocation, and it preserves all the scalability features and animation capabilities of the employed scalable mesh codec.

A parallel finite element simulator for ion transport through three-dimensional ion channel systems.

PubMed

Tu, Bin; Chen, Minxin; Xie, Yan; Zhang, Linbo; Eisenberg, Bob; Lu, Benzhuo

2013-09-15

A parallel finite element simulator, ichannel, is developed for ion transport through three-dimensional ion channel systems that consist of protein and membrane. The coordinates of heavy atoms of the protein are taken from the Protein Data Bank and the membrane is represented as a slab. The simulator contains two components: a parallel adaptive finite element solver for a set of Poisson-Nernst-Planck (PNP) equations that describe the electrodiffusion process of ion transport, and a mesh generation tool chain for ion channel systems, which is an essential component for the finite element computations. The finite element method has advantages in modeling irregular geometries and complex boundary conditions. We have built a tool chain to get the surface and volume mesh for ion channel systems, which consists of a set of mesh generation tools. The adaptive finite element solver in our simulator is implemented using the parallel adaptive finite element package Parallel Hierarchical Grid (PHG) developed by one of the authors, which provides the capability of doing large scale parallel computations with high parallel efficiency and the flexibility of choosing high order elements to achieve high order accuracy. The simulator is applied to a real transmembrane protein, the gramicidin A (gA) channel protein, to calculate the electrostatic potential, ion concentrations and I - V curve, with which both primitive and transformed PNP equations are studied and their numerical performances are compared. To further validate the method, we also apply the simulator to two other ion channel systems, the voltage dependent anion channel (VDAC) and α-Hemolysin (α-HL). The simulation results agree well with Brownian dynamics (BD) simulation results and experimental results. Moreover, because ionic finite size effects can be included in PNP model now, we also perform simulations using a size-modified PNP (SMPNP) model on VDAC and α-HL. It is shown that the size effects in SMPNP can effectively lead to reduced current in the channel, and the results are closer to BD simulation results. Copyright © 2013 Wiley Periodicals, Inc.

LMC: Logarithmantic Monte Carlo

NASA Astrophysics Data System (ADS)

Mantz, Adam B.

2017-06-01

LMC is a Markov Chain Monte Carlo engine in Python that implements adaptive Metropolis-Hastings and slice sampling, as well as the affine-invariant method of Goodman & Weare, in a flexible framework. It can be used for simple problems, but the main use case is problems where expensive likelihood evaluations are provided by less flexible third-party software, which benefit from parallelization across many nodes at the sampling level. The parallel/adaptive methods use communication through MPI, or alternatively by writing/reading files, and mostly follow the approaches pioneered by CosmoMC (ascl:1106.025).

Massively parallel multicanonical simulations

NASA Astrophysics Data System (ADS)

Gross, Jonathan; Zierenberg, Johannes; Weigel, Martin; Janke, Wolfhard

2018-03-01

Generalized-ensemble Monte Carlo simulations such as the multicanonical method and similar techniques are among the most efficient approaches for simulations of systems undergoing discontinuous phase transitions or with rugged free-energy landscapes. As Markov chain methods, they are inherently serial computationally. It was demonstrated recently, however, that a combination of independent simulations that communicate weight updates at variable intervals allows for the efficient utilization of parallel computational resources for multicanonical simulations. Implementing this approach for the many-thread architecture provided by current generations of graphics processing units (GPUs), we show how it can be efficiently employed with of the order of 104 parallel walkers and beyond, thus constituting a versatile tool for Monte Carlo simulations in the era of massively parallel computing. We provide the fully documented source code for the approach applied to the paradigmatic example of the two-dimensional Ising model as starting point and reference for practitioners in the field.

Improving the scalability of hyperspectral imaging applications on heterogeneous platforms using adaptive run-time data compression

NASA Astrophysics Data System (ADS)

Plaza, Antonio; Plaza, Javier; Paz, Abel

2010-10-01

Latest generation remote sensing instruments (called hyperspectral imagers) are now able to generate hundreds of images, corresponding to different wavelength channels, for the same area on the surface of the Earth. In previous work, we have reported that the scalability of parallel processing algorithms dealing with these high-dimensional data volumes is affected by the amount of data to be exchanged through the communication network of the system. However, large messages are common in hyperspectral imaging applications since processing algorithms are pixel-based, and each pixel vector to be exchanged through the communication network is made up of hundreds of spectral values. Thus, decreasing the amount of data to be exchanged could improve the scalability and parallel performance. In this paper, we propose a new framework based on intelligent utilization of wavelet-based data compression techniques for improving the scalability of a standard hyperspectral image processing chain on heterogeneous networks of workstations. This type of parallel platform is quickly becoming a standard in hyperspectral image processing due to the distributed nature of collected hyperspectral data as well as its flexibility and low cost. Our experimental results indicate that adaptive lossy compression can lead to improvements in the scalability of the hyperspectral processing chain without sacrificing analysis accuracy, even at sub-pixel precision levels.

Relationships among classes of self-oscillating transistor parallel inverters. [for power conditioning applications

NASA Technical Reports Server (NTRS)

Wilson, T. G.; Lee, F. C. Y.; Burns, W. W., III; Owen, H. A., Jr.

1975-01-01

It recently has been shown in the literature that many dc-to-square-wave parallel inverters which are widely used in power-conditioning applications can be grouped into one of two families. Each family is characterized by an equivalent RLC network. Based on this approach, a classification procedure is presented for self-oscillating parallel inverters which makes evident natural relationships which exist between various inverter configurations. By utilizing concepts from the basic theory of negative resistance oscillators and the principle of duality as applied to nonlinear networks, a chain of relationships is established which enables a methodical transfer of knowledge gained about one family of inverters to any of the other families in the classification array.

Excitation of a Parallel Plate Waveguide by an Array of Rectangular Waveguides

NASA Technical Reports Server (NTRS)

Rengarajan, Sembiam

2011-01-01

This work addresses the problem of excitation of a parallel plate waveguide by an array of rectangular waveguides that arises in applications such as the continuous transverse stub (CTS) antenna and dual-polarized parabolic cylindrical reflector antennas excited by a scanning line source. In order to design the junction region between the parallel plate waveguide and the linear array of rectangular waveguides, waveguide sizes have to be chosen so that the input match is adequate for the range of scan angles for both polarizations. Electromagnetic wave scattered by the junction of a parallel plate waveguide by an array of rectangular waveguides is analyzed by formulating coupled integral equations for the aperture electric field at the junction. The integral equations are solved by the method of moments. In order to make the computational process efficient and accurate, the method of weighted averaging was used to evaluate rapidly oscillating integrals encountered in the moment matrix. In addition, the real axis spectral integral is evaluated in a deformed contour for speed and accuracy. The MoM results for a large finite array have been validated by comparing its reflection coefficients with corresponding results for an infinite array generated by the commercial finite element code, HFSS. Once the aperture electric field is determined by MoM, the input reflection coefficients at each waveguide port, and coupling for each polarization over the range of useful scan angles, are easily obtained. Results for the input impedance and coupling characteristics for both the vertical and horizontal polarizations are presented over a range of scan angles. It is shown that the scan range is limited to about 35 for both polarizations and therefore the optimum waveguide is a square of size equal to about 0.62 free space wavelength.

Transverse spin correlations of the random transverse-field Ising model

NASA Astrophysics Data System (ADS)

Iglói, Ferenc; Kovács, István A.

2018-03-01

The critical behavior of the random transverse-field Ising model in finite-dimensional lattices is governed by infinite disorder fixed points, several properties of which have already been calculated by the use of the strong disorder renormalization-group (SDRG) method. Here we extend these studies and calculate the connected transverse-spin correlation function by a numerical implementation of the SDRG method in d =1 ,2 , and 3 dimensions. At the critical point an algebraic decay of the form ˜r-ηt is found, with a decay exponent being approximately ηt≈2 +2 d . In d =1 the results are related to dimer-dimer correlations in the random antiferromagnetic X X chain and have been tested by numerical calculations using free-fermionic techniques.

Periodically driven ergodic and many-body localized quantum systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ponte, Pedro; Department of Physics and Astronomy, University of Waterloo, ON N2L 3G1; Chandran, Anushya

2015-02-15

We study dynamics of isolated quantum many-body systems whose Hamiltonian is switched between two different operators periodically in time. The eigenvalue problem of the associated Floquet operator maps onto an effective hopping problem. Using the effective model, we establish conditions on the spectral properties of the two Hamiltonians for the system to localize in energy space. We find that ergodic systems always delocalize in energy space and heat up to infinite temperature, for both local and global driving. In contrast, many-body localized systems with quenched disorder remain localized at finite energy. We support our conclusions by numerical simulations of disorderedmore » spin chains. We argue that our results hold for general driving protocols, and discuss their experimental implications.« less

Crystal structure of ethyl (E)-2-cyano-3-(thio-phen-2-yl)acrylate: two conformers forming a discrete disorder.

PubMed

Castro Agudelo, Brian; Cárdenas, Juan C; Macías, Mario A; Ochoa-Puentes, Cristian; Sierra, Cesar A

2017-09-01

In the title compound, C 10 H 9 NO 2 S, all the non-H atoms, except for the ethyl fragment, lie nearly in the same plane. Despite the mol-ecular planarity, the ethyl fragment presents more than one conformation, giving rise to a discrete disorder, which was modelled with two different crystallographic sites for the eth-oxy O and eth-oxy α-C atoms, with occupancy values of 0.5. In the crystal, the three-dimensional array is mainly directed by C-H⋯(O,N) inter-actions, giving rise to inversion dimers with R 2 2 (10) and R 2 2 (14) motifs and infinite chains running along the [100] direction.

Discrete-time Markovian stochastic Petri nets

NASA Technical Reports Server (NTRS)

Ciardo, Gianfranco

1995-01-01

We revisit and extend the original definition of discrete-time stochastic Petri nets, by allowing the firing times to have a 'defective discrete phase distribution'. We show that this formalism still corresponds to an underlying discrete-time Markov chain. The structure of the state for this process describes both the marking of the Petri net and the phase of the firing time for each transition, resulting in a large state space. We then modify the well-known power method to perform a transient analysis even when the state space is infinite, subject to the condition that only a finite number of states can be reached in a finite amount of time. Since the memory requirements might still be excessive, we suggest a bounding technique based on truncation.

Exact Correlation Functions in S U (2 ) N =2 Superconformal QCD

NASA Astrophysics Data System (ADS)

Baggio, Marco; Niarchos, Vasilis; Papadodimas, Kyriakos

2014-12-01

We report an exact solution of 2- and 3-point functions of chiral primary fields in S U (2 ) N =2 super-Yang-Mills theory coupled to four hypermultiplets. It is shown that these correlation functions are nontrivial functions of the gauge coupling, obeying differential equations which take the form of the semi-infinite Toda chain. We solve these equations recursively in terms of the Zamolodchikov metric that can be determined exactly from supersymmetric localization on the four-sphere. Our results are verified independently in perturbation theory with a Feynman diagram computation up to 2 loops. This is a short version of a companion paper that contains detailed technical remarks, additional material, and aspects of an extension to the S U (N ) gauge group.

Isospin degree of freedom in even-even 68-76Ge and 62-70Zn isotopes

NASA Astrophysics Data System (ADS)

Jalili Majarshin, A.

2018-01-01

The introduction of isotopic spin is significant in light nuclei as Ge and Zn isotopes in order to take into account isospin effects on energy spectra. Dynamical symmetries in spherical, γ-soft limits and transition in the interacting boson model IBM-3 are analyzed. Analytic expressions and exact eigenenergies, electromagnetic transitions probabilities are obtained for the transition between spherical and γ-soft shapes by using the Bethe ansatz within an infinite-dimensional Lie algebra in light mass nuclei. The corresponding algebraic structure and reduction chain are studied in IBM-3. For examples, the nuclear structure of the 68-76Ge and 62-70Zn isotopes is calculated in IBM-3 and compared with experimental results.

Rotation of an immersed cylinder sliding near a thin elastic coating

NASA Astrophysics Data System (ADS)

Rallabandi, Bhargav; Saintyves, Baudouin; Jules, Theo; Salez, Thomas; Schönecker, Clarissa; Mahadevan, L.; Stone, Howard A.

2017-07-01

It is known that an object translating parallel to a soft wall in a viscous fluid produces hydrodynamic stresses that deform the wall, which in turn results in a lift force on the object. Recent experiments with cylinders sliding under gravity near a soft incline, which confirmed theoretical arguments for the lift force, also reported an unexplained steady-state rotation of the cylinders [B. Saintyves et al., Proc. Natl. Acad. Sci. USA 113, 5847 (2016), 10.1073/pnas.1525462113]. Motivated by these observations, we show, in the lubrication limit, that an infinite cylinder that translates in a viscous fluid parallel to a soft wall at constant speed and separation distance must also rotate in order to remain free of torque. Using the Lorentz reciprocal theorem, we show analytically that for small deformations of the elastic layer, the angular velocity of the cylinder scales with the cube of the sliding speed. These predictions are confirmed numerically. We then apply the theory to the gravity-driven motion of a cylinder near a soft incline and find qualitative agreement with the experimental observations, namely, that a softer elastic layer results in a greater angular speed of the cylinder.

Crystal structure of BaMn2(AsO4)2 containing discrete [Mn4O18]28- units.

PubMed

Alcantar, Salvador; Ledbetter, Hollis R; Ranmohotti, Kulugammana G S

2017-12-01

In our attempt to search for mixed alkaline-earth and transition metal arsenates, the title compound, barium dimanganese(II) bis-(arsenate), has been synthesized by employing a high-temperature RbCl flux. The crystal structure of BaMn 2 (AsO 4 ) 2 is made up of MnO 6 octa-hedra and AsO 4 tetra-hedra assembled by sharing corners and edges into infinite slabs with composition [Mn 2 (AsO 4 ) 2 ] 2- that extend parallel to the ab plane. The barium cations reside between parallel slabs maintaining the inter-slab connectivity through coordination to eight oxygen anions. The layered anionic framework comprises weakly inter-acting [Mn 4 O 18 ] 28- tetra-meric units. In each tetra-mer, the manganese(II) cations are in a planar arrangement related by a center of inversion. Within the slabs, the tetra-meric units are separated from each other by 6.614 (2) Å (Mn⋯Mn distances). The title compound has isostructural analogues amongst synthetic Sr M 2 ( X O 4 ) 2 compounds with M = Ni, Co, and X = As, P.

Analysis of liquid-metal-jet impingement cooling in a corner region and for a row of jets

NASA Technical Reports Server (NTRS)

Siegel, R.

1975-01-01

A conformal mapping method was used to analyze liquid-metal-jet impingement heat transfer. The jet flow region and energy equation are transformed to correspond to uniform flow in a parallel plate channel with nonuniform heat addition along a portion of one wall. The exact solution for the wall-temperature distribution was obtained in the transformed channel, and the results are mapped back into the physical plane. Two geometries are analyzed. One is for a single slot jet directed either into an interior corner formed by two flat plates, or over the external sides of the corner; the flat plates are uniformly heated, and the corner can have various included angles. The heat-transfer coefficient at the stagnation point at the apex of the plates is obtained as a function of the corner angle, and temperature distributions are calculated along the heated walls. The second geometry is an infinite row of uniformly spaced parallel slot jets impinging normally against a uniformly heated plate. The heat-transfer behavior is obtained as a function of the spacing between the jets. Results are given for several jet Peclet numbers from 5 to 50.

Parallel Quantum Circuit in a Tunnel Junction

NASA Astrophysics Data System (ADS)

Faizy Namarvar, Omid; Dridi, Ghassen; Joachim, Christian

2016-07-01

Spectral analysis of 1 and 2-states per line quantum bus are normally sufficient to determine the effective Vab(N) electronic coupling between the emitter and receiver states through the bus as a function of the number N of parallel lines. When Vab(N) is difficult to determine, an Heisenberg-Rabi time dependent quantum exchange process must be triggered through the bus to capture the secular oscillation frequency Ωab(N) between those states. Two different linear and regimes are demonstrated for Ωab(N) as a function of N. When the initial preparation is replaced by coupling of the quantum bus to semi-infinite electrodes, the resulting quantum transduction process is not faithfully following the Ωab(N) variations. Because of the electronic transparency normalisation to unity and of the low pass filter character of this transduction, large Ωab(N) cannot be captured by the tunnel junction. The broadly used concept of electrical contact between a metallic nanopad and a molecular device must be better described as a quantum transduction process. At small coupling and when N is small enough not to compensate for this small coupling, an N2 power law is preserved for Ωab(N) and for Vab(N).

Parallel Quantum Circuit in a Tunnel Junction

PubMed Central

Faizy Namarvar, Omid; Dridi, Ghassen; Joachim, Christian

2016-01-01

Spectral analysis of 1 and 2-states per line quantum bus are normally sufficient to determine the effective Vab(N) electronic coupling between the emitter and receiver states through the bus as a function of the number N of parallel lines. When Vab(N) is difficult to determine, an Heisenberg-Rabi time dependent quantum exchange process must be triggered through the bus to capture the secular oscillation frequency Ωab(N) between those states. Two different linear and regimes are demonstrated for Ωab(N) as a function of N. When the initial preparation is replaced by coupling of the quantum bus to semi-infinite electrodes, the resulting quantum transduction process is not faithfully following the Ωab(N) variations. Because of the electronic transparency normalisation to unity and of the low pass filter character of this transduction, large Ωab(N) cannot be captured by the tunnel junction. The broadly used concept of electrical contact between a metallic nanopad and a molecular device must be better described as a quantum transduction process. At small coupling and when N is small enough not to compensate for this small coupling, an N2 power law is preserved for Ωab(N) and for Vab(N). PMID:27453262

Parallel Quantum Circuit in a Tunnel Junction.

PubMed

Faizy Namarvar, Omid; Dridi, Ghassen; Joachim, Christian

2016-07-25

Spectral analysis of 1 and 2-states per line quantum bus are normally sufficient to determine the effective Vab(N) electronic coupling between the emitter and receiver states through the bus as a function of the number N of parallel lines. When Vab(N) is difficult to determine, an Heisenberg-Rabi time dependent quantum exchange process must be triggered through the bus to capture the secular oscillation frequency Ωab(N) between those states. Two different linear and regimes are demonstrated for Ωab(N) as a function of N. When the initial preparation is replaced by coupling of the quantum bus to semi-infinite electrodes, the resulting quantum transduction process is not faithfully following the Ωab(N) variations. Because of the electronic transparency normalisation to unity and of the low pass filter character of this transduction, large Ωab(N) cannot be captured by the tunnel junction. The broadly used concept of electrical contact between a metallic nanopad and a molecular device must be better described as a quantum transduction process. At small coupling and when N is small enough not to compensate for this small coupling, an N(2) power law is preserved for Ωab(N) and for Vab(N).

Casimir-Lifshitz interaction between dielectrics of arbitrary geometry: A dielectric contrast perturbation theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golestanian, Ramin

2009-07-15

The general theory of electromagnetic-fluctuation-induced interactions in dielectric bodies as formulated by Dzyaloshinskii, Lifshitz, and Pitaevskii is rewritten as a perturbation theory in terms of the spatial contrast in (imaginary) frequency dependent dielectric function. The formulation can be used to calculate the Casimir-Lifshitz forces for dielectric objects of arbitrary geometry, as a perturbative expansion in the dielectric contrast, and could thus complement the existing theories that use perturbation in geometrical features. We find that expansion in dielectric contrast recasts the resulting Lifshitz energy into a sum of the different many-body contributions. The limit of validity and convergence properties of themore » perturbation theory is discussed using the example of parallel semi-infinite objects for which the exact result is known.« less

Nonlinear wave interaction in a plasma column

NASA Technical Reports Server (NTRS)

Larsen, J.

1972-01-01

Two particular cases of nonlinear wave interaction in a plasma column were investigated. The frequencies of the waves were on the order of magnitude of the electron plasma frequency, and ion motion was neglected. The nonlinear coupling of slow waves on a plasma column was studied by means of cold plasma theory, and the case of a plasma column surrounded by an infinite dielectric in the absence of a magnetic field was also examined. Nonlinear scattering from a plasma column in an electromagnetic field having it's magnetic field parallel to the axis of the column was investigated. Some experimental results on mode conversion in the presence of loss are presented along with some observations of nonlinear scattering, The effect of the earth's magnetic field and of discharge symmetry on the radiation pattern are discussed.

Mean-field theory of active electrolytes: Dynamic adsorption and overscreening

NASA Astrophysics Data System (ADS)

Frydel, Derek; Podgornik, Rudolf

2018-05-01

We investigate active electrolytes within the mean-field level of description. The focus is on how the double-layer structure of passive, thermalized charges is affected by active dynamics of constituting ions. One feature of active dynamics is that particles adhere to hard surfaces, regardless of chemical properties of a surface and specifically in complete absence of any chemisorption or physisorption. To carry out the mean-field analysis of the system that is out of equilibrium, we develop the "mean-field simulation" technique, where the simulated system consists of charged parallel sheets moving on a line and obeying active dynamics, with the interaction strength rescaled by the number of sheets. The mean-field limit becomes exact in the limit of an infinite number of movable sheets.

Infinite Multiplets

DOE R&D Accomplishments Database

Nambu, Y.

1967-01-01

The main ingredients of the method of infinite multiplets consist of: 1) the use of wave functions with an infinite number of components for describing an infinite tower of discrete states of an isolated system (such as an atom, a nucleus, or a hadron), 2) the use of group theory, instead of dynamical considerations, in determining the properties of the wave functions.

Boundary Conditions for Infinite Conservation Laws

NASA Astrophysics Data System (ADS)

Rosenhaus, V.; Bruzón, M. S.; Gandarias, M. L.

2016-12-01

Regular soliton equations (KdV, sine-Gordon, NLS) are known to possess infinite sets of local conservation laws. Some other classes of nonlinear PDE possess infinite-dimensional symmetries parametrized by arbitrary functions of independent or dependent variables; among them are Zabolotskaya-Khokhlov, Kadomtsev-Petviashvili, Davey-Stewartson equations and Born-Infeld equation. Boundary conditions were shown to play an important role for the existence of local conservation laws associated with infinite-dimensional symmetries. In this paper, we analyze boundary conditions for the infinite conserved densities of regular soliton equations: KdV, potential KdV, Sine-Gordon equation, and nonlinear Schrödinger equation, and compare them with boundary conditions for the conserved densities obtained from infinite-dimensional symmetries with arbitrary functions of independent and dependent variables.

Large Spatial Scale Ground Displacement Mapping through the P-SBAS Processing of Sentinel-1 Data on a Cloud Computing Environment

NASA Astrophysics Data System (ADS)

Casu, F.; Bonano, M.; de Luca, C.; Lanari, R.; Manunta, M.; Manzo, M.; Zinno, I.

2017-12-01

Since its launch in 2014, the Sentinel-1 (S1) constellation has played a key role on SAR data availability and dissemination all over the World. Indeed, the free and open access data policy adopted by the European Copernicus program together with the global coverage acquisition strategy, make the Sentinel constellation as a game changer in the Earth Observation scenario. Being the SAR data become ubiquitous, the technological and scientific challenge is focused on maximizing the exploitation of such huge data flow. In this direction, the use of innovative processing algorithms and distributed computing infrastructures, such as the Cloud Computing platforms, can play a crucial role. In this work we present a Cloud Computing solution for the advanced interferometric (DInSAR) processing chain based on the Parallel SBAS (P-SBAS) approach, aimed at processing S1 Interferometric Wide Swath (IWS) data for the generation of large spatial scale deformation time series in efficient, automatic and systematic way. Such a DInSAR chain ingests Sentinel 1 SLC images and carries out several processing steps, to finally compute deformation time series and mean deformation velocity maps. Different parallel strategies have been designed ad hoc for each processing step of the P-SBAS S1 chain, encompassing both multi-core and multi-node programming techniques, in order to maximize the computational efficiency achieved within a Cloud Computing environment and cut down the relevant processing times. The presented P-SBAS S1 processing chain has been implemented on the Amazon Web Services platform and a thorough analysis of the attained parallel performances has been performed to identify and overcome the major bottlenecks to the scalability. The presented approach is used to perform national-scale DInSAR analyses over Italy, involving the processing of more than 3000 S1 IWS images acquired from both ascending and descending orbits. Such an experiment confirms the big advantage of exploiting large computational and storage resources of Cloud Computing platforms for large scale DInSAR analysis. The presented Cloud Computing P-SBAS processing chain can be a precious tool in the perspective of developing operational services disposable for the EO scientific community related to hazard monitoring and risk prevention and mitigation.

2,2′-[2,4-Bis(naphthalen-1-yl)cyclo­butane-1,3-di­yl]bis­(1-methyl­pyridinium) bis­(4-chloro­benzene­sulfonate): thermal-induced [2 + 2] cyclo­addition reaction of a heterostilbene

PubMed Central

Chantrapromma, Suchada; Chanawanno, Kullapa; Boonnak, Nawong; Fun, Hoong-Kun

2014-01-01

The asymmetric unit of the title salt, C36H32N2 2+·2C6H4ClO3S−, consists of one anion and one half-cation, the other half being generated by inversion symmetry. The dihedral angle between the pyridinium ring and the napthalene ring system in the asymmetric unit is 42.86 (6)°. In the crystal, cations and anions are linked by weak C—H⋯O inter­actions into chains along [010]. Adjacent chains are further arranged in an anti­parallel manner into sheets parallel to the bc plane. π–π inter­actions are observed involving the cations, with centroid–centroid distances of 3.7664 (8) and 3.8553 (8) Å. PMID:24860326

Compression-Induced Conformation and Orientation Changes in an n-Alkane Monolayer on a Au(111) Surface.

PubMed

Endo, Osamu; Nakamura, Masashi; Amemiya, Kenta; Ozaki, Hiroyuki

2017-04-25

The influence of the preparation method and adsorbed amount of n-tetratetracontane (n-C 44 H 90 ) on its orientation in a monolayer on the Au(111) surface is studied by near carbon K-edge X-ray absorption fine structure spectroscopy (C K-NEXAFS), scanning tunneling microscopy (STM) under ultrahigh vacuum, and infrared reflection-absorption spectroscopy (IRAS) at the electrochemical interface in sulfuric acid solution. The n-C 44 H 90 molecules form self-assembled lamellar structures with the chain axis parallel to the surface, as observed by STM. For small amounts adsorbed, the carbon plane is parallel to the surface (flat-on orientation). An increase in the adsorbed amount by ∼10-20% induces compression of the lamellar structure either along the lamellar axis or alkyl chain axis. The compressed molecular arrangement is observed by STM, and induced conformation and orientation changes are confirmed by in situ IRAS and C K-NEXAFS.

Million city traveling salesman problem solution by divide and conquer clustering with adaptive resonance neural networks.

PubMed

Mulder, Samuel A; Wunsch, Donald C

2003-01-01

The Traveling Salesman Problem (TSP) is a very hard optimization problem in the field of operations research. It has been shown to be NP-complete, and is an often-used benchmark for new optimization techniques. One of the main challenges with this problem is that standard, non-AI heuristic approaches such as the Lin-Kernighan algorithm (LK) and the chained LK variant are currently very effective and in wide use for the common fully connected, Euclidean variant that is considered here. This paper presents an algorithm that uses adaptive resonance theory (ART) in combination with a variation of the Lin-Kernighan local optimization algorithm to solve very large instances of the TSP. The primary advantage of this algorithm over traditional LK and chained-LK approaches is the increased scalability and parallelism allowed by the divide-and-conquer clustering paradigm. Tours obtained by the algorithm are lower quality, but scaling is much better and there is a high potential for increasing performance using parallel hardware.

Structure of a short-chain dehydrogenase/reductase from Bacillus anthracis

PubMed Central

Hou, Jing; Wojciechowska, Kamila; Zheng, Heping; Chruszcz, Maksymilian; Cooper, David R.; Cymborowski, Marcin; Skarina, Tatiana; Gordon, Elena; Luo, Haibin; Savchenko, Alexei; Minor, Wladek

2012-01-01

The crystal structure of a short-chain dehydrogenase/reductase from Bacillus anthracis strain ‘Ames Ancestor’ complexed with NADP has been determined and refined to 1.87 Å resolution. The structure of the enzyme consists of a Rossmann fold composed of seven parallel β-strands sandwiched by three α-­helices on each side. An NADP molecule from an endogenous source is bound in the conserved binding pocket in the syn conformation. The loop region responsible for binding another substrate forms two perpendicular short helices connected by a sharp turn. PMID:22684058

Maximally reliable Markov chains under energy constraints.

PubMed

Escola, Sean; Eisele, Michael; Miller, Kenneth; Paninski, Liam

2009-07-01

Signal-to-noise ratios in physical systems can be significantly degraded if the outputs of the systems are highly variable. Biological processes for which highly stereotyped signal generations are necessary features appear to have reduced their signal variabilities by employing multiple processing steps. To better understand why this multistep cascade structure might be desirable, we prove that the reliability of a signal generated by a multistate system with no memory (i.e., a Markov chain) is maximal if and only if the system topology is such that the process steps irreversibly through each state, with transition rates chosen such that an equal fraction of the total signal is generated in each state. Furthermore, our result indicates that by increasing the number of states, it is possible to arbitrarily increase the reliability of the system. In a physical system, however, an energy cost is associated with maintaining irreversible transitions, and this cost increases with the number of such transitions (i.e., the number of states). Thus, an infinite-length chain, which would be perfectly reliable, is infeasible. To model the effects of energy demands on the maximally reliable solution, we numerically optimize the topology under two distinct energy functions that penalize either irreversible transitions or incommunicability between states, respectively. In both cases, the solutions are essentially irreversible linear chains, but with upper bounds on the number of states set by the amount of available energy. We therefore conclude that a physical system for which signal reliability is important should employ a linear architecture, with the number of states (and thus the reliability) determined by the intrinsic energy constraints of the system.

Alternating-current conductivity and dielectric relaxation of bulk iodoargentate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Hai-Bao, E-mail: duanhaibao4660@163.com; Yu, Shan-Shan; Zhou, Hong

Graphical abstract: The electric modulus shows single dielectric relaxation process in the measured frequency range. - Highlights: • The conduction mechanism is described by quantum mechanical tunneling model. • The applications of dielectric modulus give a simple method for evaluating the activation energy of the dielectric relaxation. • The [Ag{sub 2}I{sub 4}]{sup 2−}1-D chain and [Cu(en){sub 2}]{sup 2+} cation column form the layered stacks by hydrogen bond interactions. - Abstract: An inorganic-organic hybrid compound Cu(en){sub 2}Ag{sub 2}I{sub 4} (en = ethylenediamine) (1) was synthesized and single crystal structurally characterized. Along the [001] direction, the inorganic parts form an infinite 1-Dmore » chain and [Cu(en){sub 2}]{sup 2+} cations are separated by inorganic chain. The electrical conductivity and dielectric properties of 1 have been investigated over wide ranges of frequency. The alternating-current conductivities have been fitted to the Almond–West type power law expression with use of a single value of S. It is found that S values for 1 are nearly temperature-independent, which indicates that the conduction mechanism could be quantum mechanical tunneling (QMT) model. The dielectric loss and electric modulus show single dielectric relaxation process. The activation energy obtained from temperature-dependent electric modulus compare with the calculated from the dc conductivity plots.« less

Single-coil properties and concentration effects for polyelectrolyte-like wormlike micelles: a Monte Carlo study

NASA Astrophysics Data System (ADS)

Cannavacciuolo, Luigi; Skov Pedersen, Jan; Schurtenberger, Peter

2002-03-01

Results of an extensive Monte Carlo (MC) study on both single and many semiflexible charged chains with excluded volume (EV) are summarized. The model employed has been tailored to mimic wormlike micelles in solution. Simulations have been performed at different ionic strengths of added salt, charge densities, chain lengths and volume fractions Φ, covering the dilute to concentrated regime. At infinite dilution the scattering functions can be fitted by the same fitting functions as for uncharged semiflexible chains with EV, provided that an electrostatic contribution bel is added to the bare Kuhn length. The scaling of bel is found to be more complex than the Odijk-Skolnick-Fixman predictions, and qualitatively compatible with more recent variational calculations. Universality in the scaling of the radius of gyration is found if all lengths are rescaled by the total Kuhn length. At finite concentrations, the simple model used is able to reproduce the structural peak in the scattering function S(q) observed in many experiments, as well as other properties of polyelectrolytes (PELs) in solution. Universal behaviour of the forward scattering S(0) is established after a rescaling of Φ. MC data are found to be in very good agreement with experimental scattering measurements with equilibrium PELs, which are giant wormlike micelles formed in mixtures of nonionic and ionic surfactants in dilute aqueous solution, with added salt.

From Intermolecular Interactions to Texture in Polycrystalline Surfaces of 1,ω-alkanediols (ω = 10-13).

PubMed

Luis-Raya, Gilgamesh; Ramírez-Cardona, Màrius; Luna-Bárcenas, Gabriel; Hernández-Landaverde, Martín A; Jiménez-Nieto, Adair; García-Rivas, Jose Luis; España-Sánchez, Beatriz Liliana; Sanchez, Isaac C

2017-06-08

Differences on herringbone molecular arrangement in two forms of long-chain 1,ω-alkanediols (C n H 2 n +2 O₂ with n = 10, 11, 12, 13) are explained from the analysis of O-H···O hydrogen-bond sequences in infinite chains and the role of a C-H···O intramolecular hydrogen-bond in stabilization of a gauche defect, as well as the inter-grooving effectiveness on molecular packing. GIXD (Glancing Incidence X-ray Diffraction) experiments were conducted on polycrystalline monophasic samples. Diffracted intensities were treated with the multi-axial March-Dollase method to correlate energetic and geometrical features of molecular interactions with the crystalline morphology and textural pattern of samples. The monoclinic (P 2 ₁/ c , Z = 2) crystals of the even-numbered members ( n = 10, 12; DEDOL and DODOL, respectively) are diametrical prisms with combined form {104}/{-104}/{001} and present a two-fold platelet-like preferred orientation, whereas orthorhombic (P 2 ₁ 2 ₁ 2 ₁, Z = 4) odd-numbered members ( n = 11, 13; UNDOL and TRDOL, respectively) present a dominant needle-like orientation on direction [101] (fiber texture). We show that crystalline structures of medium complexity and their microstructures can be determined from rapid GIXD experiments from standard radiation, combined with molecular replacement procedure using crystal structures of compounds with higher chain lengths as reference data.

Identification of globular mechanochemical heads of kinesin.

PubMed

Scholey, J M; Heuser, J; Yang, J T; Goldstein, L S

1989-03-23

Kinesin is a mechanoenzyme which uses energy liberated from ATP hydrolysis to transport particles towards the 'plus ends' of microtubules. The enzyme consists of two polypeptide heavy chains of relative molecular mass (Mr) approximately 110,000-140,000 (110K-140K) plus copurifying light chains; these polypeptides are arranged in a structure consisting of two globular heads attached to a fibrous stalk which terminates in a 'feathered' tail. Here we report that a function-disrupting monoclonal antikinesin, which binds to the 45K fragment of the kinesin heavy chain, recognizes an epitope located towards the N-terminal end of the heavy chain, and decorates the two globular heads lying at one end of the intact molecules (one antibody per head). The results show that the two heavy chains of native kinesin are arranged in parallel, and that the 45K fragments, which display nucleotide-sensitive interactions with microtubules, represent mechanochemical 'heads' located at the N-terminal regions of the heavy chains. Thus, it is likely that the kinesin heads are analogous to the subfragment-1 domains of myosin.

Finite size effect on hydrogen bond cooperativity in (Ala)n polypeptides: A DFT study using numeric atom-centered orbitals

NASA Astrophysics Data System (ADS)

Blum, Volker; Ireta, Joel; Scheffler, Matthias

2007-03-01

An accurate representation of the energetic contribution Ehb of hydrogen bonds to structure formation is paramount to understand the secondary structure stability of proteins, both qualitatively and quantitatively. However, Ehb depends strongly on its environment, and even on the surrounding peptide conformation itself. For instance, a short α-helical polypeptide (Ala)4 can not be stabilized by its single hydrogen bond, whereas an infinite α-helical chain (Ala)∞ is clearly energetically stable over a fully extended conformation. We here use all-electron density functional calculations in the PBE generalized gradient approximation by a recently developed, computationally efficient numeric atom-centered orbital based code^1 to investigate this H-bond cooperativity that is intrinsic to Alanine-based polypeptides (Ala)n (n=1-20,∞). We compare finite and infinite prototypical helical conformations (α, π, 310) on equal footing, with both neutral and ionic termination for finite (Ala)n peptides. Moderately sized NAO basis sets allow to capture Ehb with meV accuracy, revealing a clear jump in Ehb (cooperativity) when two H-bonds first appear in line, followed by slower and more continuous increase of Ehb towards n->∞. ^1 V. Blum, R. Gehrke, P. Havu, V. Havu, M. Scheffler, The FHI Ab Initio Molecular Simulations (aims) Project, Fritz-Haber-Institut, Berlin (2006).

Solid dispersions of Myricetin with enhanced solubility: Formulation, characterization and crystal structure of stability-impeding Myricetin monohydrate crystals

NASA Astrophysics Data System (ADS)

Mureşan-Pop, M.; Pop, M. M.; Borodi, G.; Todea, M.; Nagy-Simon, T.; Simon, S.

2017-08-01

Three solid dispersion forms of Myricetin combined with the Polyvinylpyrrolidone were successfully prepared by spray drying method, and characterized by X-ray powder diffraction, thermal analysis, infrared spectroscopy and optical microscopy. Zeta potential measurements provided indications on solid dispersions stability in aqueous suspension related to their storage at elevated temperature and relative humidity, which depends on the Myricetin load. By increase of Myricetin load, the stability of the solid dispersion is impeded due to growth of Myricetin monohydrate crystals. The amorphous dispersions with 10% and 50% Myricetin load are stable and, compared to pure Myricetin, their aqueous solubility is enhanced by a factor of 47 and 13, respectively. The dispersion with 80% Myricetin load is unstable on storage, and this behavior acts in conjunction with the development of Myricetin monohydrate crystals. Single-crystal X-ray diffraction results obtained for Myricetin monohydrate reveal a structure of an infinite 2D network of hydrogen-bonded molecules involving all six hydroxyl groups of Myricetin. The water molecules are positioned in between the infinite chains, and contribute via H-bonds to robust crystal packing. The calculated needle-like morphology of monohydrate form is in agreement with the optical microscopy results. The study shows that the solid amorphous dispersions with up to 50% Myricetin load are a viable option for achieving substantial solubility improvement of Myricetin, and supports their potential use in pharmaceutical applications.

Construction and optical properties of infinite Cd and finite Cu molecules stairs

NASA Astrophysics Data System (ADS)

Zhao, Qiang; Mao, Wutao; Shen, Zhi; Wang, Qinghong; Zhou, Qian

2017-02-01

Two coordination complexes, namely [(hpdq)(pta)Cd]n (1) and [(pptp)(pta)Cu2Cl] (2) have been synthesized by solvothermal method based on two polypyridyl ligands, 2,3,6,7,10,11-hexakis- (2-pyridyl)dipyrazino[2,3-f:2‧,3‧-h]quinoxaline) (hpdq), 4‧-(4- (3H-pyrrol-3-yl)phenyl)- 2,2‧:6‧,2″- terpyridine (pptp) and auxiliary ligand p-phthalic acid (pta), respectively. Single crystal x-ray diffraction analyses reveal that complexes 1 and 2 assembled based on distinct asymmetric unit comprising one and two respective polypyridyl ligands but one Cd(II) and two Cu(I)ions, respectively. Among them, The asymmetric units in 1 was extended to one dimensional chain via the link of auxiliary ligand pta, just like infinite layers of stairs that connected by cadmium ions as the node. While that in 2 to Zero dimensional tetranuclear structure via the link of auxiliary ligand pta, just like finite four layers of stairs that Copper ion as the node connection. Furthermore, solid fluorescence spectra properties of two complexes were also investigated, and the result shows the fluorescence intensity of complex 1 is stronger than that of the hpdq ligand, but the fluorescence intensity of complex 2 is weaker than that of the pptp ligand. CCDC number of 1and 2 are 1483301 and 1483302.

Implications of hydrogen/halogen-bond in the stabilization of confined water and anion-water clusters by a cationic receptor

NASA Astrophysics Data System (ADS)

Hoque, Md. Najbul; Das, Gopal

2016-03-01

Anion complexation of benzene capped flexible tripodal receptor and solid state stabilization of discrete hybrid anion-water or infinite water clusters by various supramolecular interactions are reported here. The crystal structure of the receptor in protonated states shows all the three arms projected in one direction. We structurally demonstrate discrete fluoride-water cluster [F2-H2O]2- and square shaped chloride-water cluster [Cl2-(H2O)2]2- inside the cationic channel of the receptor. Structural analysis also reveals that these clusters are stabilized inside the channel through active participation of N/C/Ow‧H⋯Ow, N/C/Ow‧H⋯X- (X- = F-, Cl- and I-) H-bonds and electrostatic interactions. Moreover, C-H⋯π and π⋯π types weak intermolecular interactions appear to play crucial role in supramolecular assembly of receptor. Additionally, on treatment with hydroiodic acid (HI) L resulted zwitterionic iodide complex. Crystal structure reveals the presence of S···I halogen bonded dimer, I2···I halogen bond, 1D infinite water chain and neutral iodine molecules. It is comprehensible that ligand basal structure (benzene capped and N-bridge head in two tripodal) play crucial roles in the formation of diverse halide-water cluster. All structures were well examined by different techniques such as NMR, IR, TGA, DSC, PXRD and XRD.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuura, Yukihito, E-mail: matsuura@chem.nara-k.ac.jp

The tunneling magnetoresistance (TMR) of a silicon chain sandwiched between nickel electrodes was examined by using first-principles density functional theory. The relative orientation of the magnetization in a parallel-alignment (PA) configuration of two nickel electrodes enhanced the current with a bias less than 0.4 V compared with that in an antiparallel-alignment configuration. Consequently, the silicon chain-nickel electrodes yielded good TMR characteristics. In addition, there was polarized spin current in the PA configuration. The spin polarization of sulfur atoms functioning as a linking bridge between the chain and nickel electrode played an important role in the magnetic effects of the electric current.more » Moreover, the hybridization of the sulfur 3p orbital and σ-conjugated silicon 3p orbital contributed to increasing the total current.« less

Parallel and automated library synthesis of 2-long alkyl chain benzoazoles and azole[4,5-b]pyridines under microwave irradiation.

PubMed

Martínez-Palou, Rafael; Zepeda, L Gerardo; Höpfl, Herbert; Montoya, Ascensión; Guzmán-Lucero, Diego J; Guzmán, Javier

2005-01-01

A versatile route to 40-membered library of 2-long alkyl chain substituted benzoazoles (1 and 2) and azole[4,5-b]pyridines (3 and 4) via microwave-assisted combinatorial synthesis was developed. The reactions were carried out in both monomode and multimode microwave oven. With the latter, all reactions were performed in high-throughput experimental settings consisting of an 8 x 5 combinatorial library designed to synthesize 40 compounds. Each step, from the addition of reagents to the recovery of final products, was automated. The microwave-assisted N-long chain alkylation reactions of 2-alkyl-1H-benzimidazole (1) and 2-alkyl-1H-benzimidazole[4,5-b] pyridines (3) were also studied.

1H-Indole-3-carbaldehyde

PubMed Central

Dileep, C. S.; Abdoh, M. M. M.; Chakravarthy, M. P.; Mohana, K. N.; Sridhar, M. A.

2012-01-01

In the title compound, C9H7NO, the benzene ring forms a dihedral angle of 3.98 (12)° with the pyrrole ring. In the crystal, N–H⋯O hydrogen bonds links the mol­ecules into chains which run parallel to [02-1]. PMID:23284457

Metrics for Labeled Markov Systems

NASA Technical Reports Server (NTRS)

Desharnais, Josee; Jagadeesan, Radha; Gupta, Vineet; Panangaden, Prakash

1999-01-01

Partial Labeled Markov Chains are simultaneously generalizations of process algebra and of traditional Markov chains. They provide a foundation for interacting discrete probabilistic systems, the interaction being synchronization on labels as in process algebra. Existing notions of process equivalence are too sensitive to the exact probabilities of various transitions. This paper addresses contextual reasoning principles for reasoning about more robust notions of "approximate" equivalence between concurrent interacting probabilistic systems. The present results indicate that:We develop a family of metrics between partial labeled Markov chains to formalize the notion of distance between processes. We show that processes at distance zero are bisimilar. We describe a decision procedure to compute the distance between two processes. We show that reasoning about approximate equivalence can be done compositionally by showing that process combinators do not increase distance. We introduce an asymptotic metric to capture asymptotic properties of Markov chains; and show that parallel composition does not increase asymptotic distance.

Aggregation and Gelation of Aromatic Polyamides with Parallel and Anti-parallel Alignment of Molecular Dipole Along the Backbone

NASA Astrophysics Data System (ADS)

Zhu, Dan; Shang, Jing; Ye, Xiaodong; Shen, Jian

2016-12-01

The understanding of macromolecular structures and interactions is important but difficult, due to the facts that a macromolecules are of versatile conformations and aggregate states, which vary with environmental conditions and histories. In this work two polyamides with parallel or anti-parallel dipoles along the linear backbone, named as ABAB (parallel) and AABB (anti-parallel) have been studied. By using a combination of methods, the phase behaviors of the polymers during the aggregate and gelation, i.e., the forming or dissociation processes of nuclei and fibril, cluster of fibrils, and cluster-cluster aggregation have been revealed. Such abundant phase behaviors are dominated by the inter-chain interactions, including dispersion, polarity and hydrogen bonding, and correlatd with the solubility parameters of solvents, the temperature, and the polymer concentration. The results of X-ray diffraction and fast-mode dielectric relaxation indicate that AABB possesses more rigid conformation than ABAB, and because of that AABB aggregates are of long fibers while ABAB is of hairy fibril clusters, the gelation concentration in toluene is 1 w/v% for AABB, lower than the 3 w/v% for ABAB.

Flow induced/ refined solution crystallization of a semiconducting polymer

NASA Astrophysics Data System (ADS)

Nguyen, Ngoc A.

Organic photovoltaics, a new generation of solar cells, has gained scientific and economic interests due to the ability of solution-processing and potentially low-cost power production. Though, the low power conversion efficiency of organic/ plastic solar cells is one of the most pertinent challenges that has appealed to research communities from many different fields including materials science and engineering, electrical engineering, chemical engineering, physics and chemistry. This thesis focuses on investigating and controlling the morphology of a semi-conducting, semi-crystalline polymer formed under shear-flow. Molecular structures and processing techniques are critical factors that significantly affect the morphology formation in the plastic solar cells, thus influencing device performance. In this study, flow-induced solution crystallization of poly (3-hexylthiophene) (P3HT) in a poor solvent, 2-ethylnapthalene (2-EN) was utilized to make a paint-like, structural liquid. The polymer crystals observed in this structured paint are micrometers long, nanometers in cross section and have a structure similar to that formed under quiescent conditions. There is pi-pi stacking order along the fibril axis, while polymer chain folding occurs along the fibril width and the order of the side-chain stacking is along fibril height. It was revealed that shear-flow not only induces P3HT crystallization from solution, but also refines and perfects the P3HT crystals. Thus, a general strategy to refine the semiconducting polymer crystals from solution under shear-flow has been developed and employed by simply tuning the processing (shearing) conditions with respect to the dissolution temperature of P3HT in 2-EN. The experimental results demonstrated that shear removes defects and allows more perfect crystals to be formed. There is no glass transition temperature observed in the crystals formed using the flow-induced crystallization indicating a significantly different morphology formation in comparison to that of the pristine (as-received) P3HT. As a result, single P3HT crystals with high surface energy chain folds were analyzed and determined. Previous reported results of infinite melting enthalpy of extended chain P3HT crystals are much higher than the result discovered in this study. The findings in this study revealed that the infinite melting enthalpy of chain-folded P3HT crystals is considerably decreased due to the presence of this P3HT chain-folded surface energy. In this study, the kinetics and mechanism of P3HT crystallization under shear-flow was thoroughly investigated as well. A homogeneous nucleation of P3HT was observed that allows one dimensional fibril crystal growth. The micrometer long P3HT crystals are formed and limited by the contact time between the P3HT molecules. Furthermore, it was found that phenyl-C61-butyric acid methyl ester (PCBM) nanoparticles inhibit the crystallization of P3HT under shear. However, the shear-flow leads to nanophase agglomeration of PCBM and creates percolation of P3HT fibril crystal networks and the PCBM phase separated domains that apparently present better pathways for transporting electrons and holes. Interestingly, the structured liquid was simply applied onto substrates with a paintbrush resulting in similar device performance to those made with current techniques in which the morphology is commonly formed during application or post-processing steps. These detailed findings are given and discussed in the thesis.

Temperature field determination in slabs, circular plates and spheres with saw tooth heat generating sources

NASA Astrophysics Data System (ADS)

Diestra Cruz, Heberth Alexander

The Green's functions integral technique is used to determine the conduction heat transfer temperature field in flat plates, circular plates, and solid spheres with saw tooth heat generating sources. In all cases the boundary temperature is specified (Dirichlet's condition) and the thermal conductivity is constant. The method of images is used to find the Green's function in infinite solids, semi-infinite solids, infinite quadrants, circular plates, and solid spheres. The saw tooth heat generation source has been modeled using Dirac delta function and Heaviside step function. The use of Green's functions allows obtain the temperature distribution in the form of an integral that avoids the convergence problems of infinite series. For the infinite solid and the sphere, the temperature distribution is three-dimensional and in the cases of semi-infinite solid, infinite quadrant and circular plate the distribution is two-dimensional. The method used in this work is superior to other methods because it obtains elegant analytical or quasi-analytical solutions to complex heat conduction problems with less computational effort and more accuracy than the use of fully numerical methods.

LOCAL AND GLOBAL DYNAMICS OF POLYLACTIDES. (R826733)

EPA Science Inventory

Polylactides (PLAs) are a family of degradable plastics having a component of the dipole moment both perpendicular and parallel to the polymer backbone (i.e. is a type-A polymer). We have studied the sub-glass, segmental and global chain dynamics in a series of fully amorphous...

Flexible intuitions of Euclidean geometry in an Amazonian indigene group

PubMed Central

Izard, Véronique; Pica, Pierre; Spelke, Elizabeth S.; Dehaene, Stanislas

2011-01-01

Kant argued that Euclidean geometry is synthesized on the basis of an a priori intuition of space. This proposal inspired much behavioral research probing whether spatial navigation in humans and animals conforms to the predictions of Euclidean geometry. However, Euclidean geometry also includes concepts that transcend the perceptible, such as objects that are infinitely small or infinitely large, or statements of necessity and impossibility. We tested the hypothesis that certain aspects of nonperceptible Euclidian geometry map onto intuitions of space that are present in all humans, even in the absence of formal mathematical education. Our tests probed intuitions of points, lines, and surfaces in participants from an indigene group in the Amazon, the Mundurucu, as well as adults and age-matched children controls from the United States and France and younger US children without education in geometry. The responses of Mundurucu adults and children converged with that of mathematically educated adults and children and revealed an intuitive understanding of essential properties of Euclidean geometry. For instance, on a surface described to them as perfectly planar, the Mundurucu's estimations of the internal angles of triangles added up to ∼180 degrees, and when asked explicitly, they stated that there exists one single parallel line to any given line through a given point. These intuitions were also partially in place in the group of younger US participants. We conclude that, during childhood, humans develop geometrical intuitions that spontaneously accord with the principles of Euclidean geometry, even in the absence of training in mathematics. PMID:21606377

Modeling dynamic behavior of superconducting maglev systems under external disturbances

NASA Astrophysics Data System (ADS)

Huang, Chen-Guang; Xue, Cun; Yong, Hua-Dong; Zhou, You-He

2017-08-01

For a maglev system, vertical and lateral displacements of the levitation body may simultaneously occur under external disturbances, which often results in changes in the levitation and guidance forces and even causes some serious malfunctions. To fully understand the effect of external disturbances on the levitation performance, in this work, we build a two-dimensional numerical model on the basis of Newton's second law of motion and a mathematical formulation derived from magnetoquasistatic Maxwell's equations together with a nonlinear constitutive relation between the electric field and the current density. By using this model, we present an analysis of dynamic behavior for two typical maglev systems consisting of an infinitely long superconductor and a guideway of different arrangements of infinitely long parallel permanent magnets. The results show that during the vertical movement, the levitation force is closely associated with the flux motion and the moving velocity of the superconductor. After being disturbed at the working position, the superconductor has a disturbance-induced initial velocity and then starts to periodically vibrate in both lateral and vertical directions. Meanwhile, the lateral and vertical vibration centers gradually drift along their vibration directions. The larger the initial velocity, the faster their vibration centers drift. However, the vertical drift of the vertical vibration center seems to be independent of the direction of the initial velocity. In addition, due to the lateral and vertical drifts, the equilibrium position of the superconductor in the maglev systems is not a space point but a continuous range.

DCOMP Award Lecture (Metropolis): A 3D Spectral Anelastic Hydrodynamic Code for Shearing, Stratified Flows

NASA Astrophysics Data System (ADS)

Barranco, Joseph

2006-03-01

We have developed a three-dimensional (3D) spectral hydrodynamic code to study vortex dynamics in rotating, shearing, stratified systems (eg, the atmosphere of gas giant planets, protoplanetary disks around newly forming protostars). The time-independent background state is stably stratified in the vertical direction and has a unidirectional linear shear flow aligned with one horizontal axis. Superposed on this background state is an unsteady, subsonic flow that is evolved with the Euler equations subject to the anelastic approximation to filter acoustic phenomena. A Fourier-Fourier basis in a set of quasi-Lagrangian coordinates that advect with the background shear is used for spectral expansions in the two horizontal directions. For the vertical direction, two different sets of basis functions have been implemented: (1) Chebyshev polynomials on a truncated, finite domain, and (2) rational Chebyshev functions on an infinite domain. Use of this latter set is equivalent to transforming the infinite domain to a finite one with a cotangent mapping, and using cosine and sine expansions in the mapped coordinate. The nonlinear advection terms are time integrated explicitly, whereas the Coriolis force, buoyancy terms, and pressure/enthalpy gradient are integrated semi- implicitly. We show that internal gravity waves can be damped by adding new terms to the Euler equations. The code exhibits excellent parallel performance with the Message Passing Interface (MPI). As a demonstration of the code, we simulate vortex dynamics in protoplanetary disks and the Kelvin-Helmholtz instability in the dusty midplanes of protoplanetary disks.

A 3D spectral anelastic hydrodynamic code for shearing, stratified flows

NASA Astrophysics Data System (ADS)

Barranco, Joseph A.; Marcus, Philip S.

2006-11-01

We have developed a three-dimensional (3D) spectral hydrodynamic code to study vortex dynamics in rotating, shearing, stratified systems (e.g., the atmosphere of gas giant planets, protoplanetary disks around newly forming protostars). The time-independent background state is stably stratified in the vertical direction and has a unidirectional linear shear flow aligned with one horizontal axis. Superposed on this background state is an unsteady, subsonic flow that is evolved with the Euler equations subject to the anelastic approximation to filter acoustic phenomena. A Fourier Fourier basis in a set of quasi-Lagrangian coordinates that advect with the background shear is used for spectral expansions in the two horizontal directions. For the vertical direction, two different sets of basis functions have been implemented: (1) Chebyshev polynomials on a truncated, finite domain, and (2) rational Chebyshev functions on an infinite domain. Use of this latter set is equivalent to transforming the infinite domain to a finite one with a cotangent mapping, and using cosine and sine expansions in the mapped coordinate. The nonlinear advection terms are time-integrated explicitly, the pressure/enthalpy terms are integrated semi-implicitly, and the Coriolis force and buoyancy terms are treated semi-analytically. We show that internal gravity waves can be damped by adding new terms to the Euler equations. The code exhibits excellent parallel performance with the message passing interface (MPI). As a demonstration of the code, we simulate the merger of two 3D vortices in the midplane of a protoplanetary disk.

Countability of Planck Boxes in Quantum Branching Models

NASA Astrophysics Data System (ADS)

Berezin, Alexander A.

2002-04-01

Two popular paradigms of cosmological quantum branching are Many World (MW) model of parallel universes (Everett, Deutsch) and inflationary quantum foam (IQF) model (Guth, Linde). Taking Planck L,T units as physically smallest, our Big Bang miniverse with size 10E28 cm and duration 10E18 sec has some 10E244 (N) elementary 4D Planck Boxes (PB) in its entire spacetime history. Using combinatorics, N! (about 10E10E247) is upper estimate for number of all possible 4D states, i.e. scale of "eternal return" (ER; Nietzsche, Eliade) for such miniverses. To count all states in full Megaverse (all up and down branches of infinite tree of all MW and/or IQF miniverses) we recall that all countable infinities have same (aleph-naught) cardinality (Cantor). Using Godel-type numbering, count PB in our miniverse by primes. This uses first N primes. Both MW and IQF models presume splitting of miniverses as springing (potentially) from each PB, making each PB infinitely rich, inexhaustible and unique. Next branching level is counted by integers p1Ep2, third level by p1Ep2Ep3 integers, etc, ad infinitum. To count in up and down directions from "our" miniverse, different branching subsets of powers of primes can be used at all levels of tower exponentiation. Thus, all PB in all infinitude of MW and/or IQF branches can be uniquely counted by never repeating integers (tower exponents of primes), offering escape from grim ER scenarios.

Electromagnetic Scattering by Multiple Cavities Embedded in the Infinite 2D Ground Plane

DTIC Science & Technology

2014-07-01

Electromagnetic Scattering by Multiple Cavities Embedded in the Infinite 2D Ground Plane Peijun Li 1 and Aihua W. Wood 2 1 Department of...of the electromagnetic wave scattering by multiple open cavities, which are embedded in an infinite two-dimensional ground plane . By introducing a...equation, variational formulation. I. INTRODUCTION A cavity is referred to as a local perturbation of the infinite ground plane . Given the cavity

Construction and characterization of VL-VH tail-parallel genetically engineered antibodies against staphylococcal enterotoxins.

PubMed

He, Xianzhi; Zhang, Lei; Liu, Pengchong; Liu, Li; Deng, Hui; Huang, Jinhai

2015-03-01

Staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus have increasingly given rise to human health and food safety. Genetically engineered small molecular antibody is a useful tool in immuno-detection and treatment for clinical illness caused by SEs. In this study, we constructed the V(L)-V(H) tail-parallel genetically engineered antibody against SEs by using the repertoire of rearranged germ-line immunoglobulin variable region genes. Total RNA were extracted from six hybridoma cell lines that stably express anti-SEs antibodies. The variable region genes of light chain (V(L)) and heavy chain (V(H)) were cloned by reverse transcription PCR, and their classical murine antibody structure and functional V(D)J gene rearrangement were analyzed. To construct the eukaryotic V(H)-V(L) tail-parallel co-expression vectors based on the "5'-V(H)-ivs-IRES-V(L)-3'" mode, the ivs-IRES fragment and V(L) genes were spliced by two-step overlap extension PCR, and then, the recombined gene fragment and V(H) genes were inserted into the pcDNA3.1(+) expression vector sequentially. And then the constructed eukaryotic expression clones termed as p2C2HILO and p5C12HILO were transfected into baby hamster kidney 21 cell line, respectively. Two clonal cell lines stably expressing V(L)-V(H) tail-parallel antibodies against SEs were obtained, and the antibodies that expressed intracytoplasma were evaluated by enzyme-linked immunosorbent assay, immunofluorescence assay, and flow cytometry. SEs can stimulate the expression of some chemokines and chemokine receptors in porcine IPEC-J2 cells; mRNA transcription level of four chemokines and chemokine receptors can be blocked by the recombinant SE antibody prepared in this study. Our results showed that it is possible to get functional V(L)-V(H) tail-parallel genetically engineered antibodies in same vector using eukaryotic expression system.

What band rocks the MTB? (Invited)

NASA Astrophysics Data System (ADS)

Kind, J.; García-Rubio, I.; Gehring, A. U.

2013-12-01

Magnetotactic bacteria (MTB) are a polyphyletic group of bacteria that have been found in marine and lacustrine environments and soils [e.g. 1]. The hallmark of MTB is their intracellular formation of magnetosomes, single-domain ferrimagnetic particles that are aligned in chains. The chain configuration generates a strong magnetic dipole, which is used as magnetic compass to move the MTB into their favorable habit. The term band corresponds to a frequency window of microwaves in the gigahertz (GHz) range. Ferromagnetic resonance (FMR) spectroscopy uses the microwave absorption in a magnetic field to analyze the anisotropy properties and the domain state of magnetic materials. Specific microwave frequency causes absorption in a characteristic magnetic field range. For the investigation of MTB we use S-band (4.02 GHz), X-band (9.47 GHz), and Q-band (34.16 GHz). Experiments on cultured MTB and on sediment samples of Holocene age showed that absorption in X- and Q-band occurs when the sample is in a saturated or nearly saturated state [2, 3]. By contrast, absorption in the S-band appears in lower magnetic fields, where the sample is far from saturation. All FMR spectra show two distinct low-field features that can be assigned to magnetite particles in chains, aligned parallel and perpendicular to the external magnetic field. The detailed separation of the parallel and perpendicular components in the bulk samples is hampered, because of the random orientation of the chains in the sample. The comparison of S-, X-, and Q-band shows that the lower the frequency the better the separation of the components. In the S-band FMR spectroscopy, the separation of chains parallel to the external magnetic field is supported by the internal field of the sample. This field is caused by the remanence that contributes to the external magnetic field to fulfill the resonance condition [3,4]. Considering the different FMR responses, it can be postulated that a lower microwave frequency generally leads to a better resolution of the chain configuration. Finally, for the investigation of geological samples, the application of S-band can be a powerful tool to complement the commonly used X-band FMR spectroscopy, i.e. multiple band rock the MTB. [1] Blakemore R.P., 1975, Magnetotactic bacteria, Science, 190, 377-379 [2] Mastogiacomo G., Fischer H., Garcia-Rubio I., and Gehring A. U., 2010, Ferromagnetic resonance spectroscopic response of magnetic chains in a biological matrix, J. Magn. Magn. Matter, 322, 661-663, doi: 10.1016/j.jmmm.2009.10.035 [3] Gehring A. U., Kind. J., Charilaou M., Garcia-Rubio I., 2011, S-band ferromagnetic resonance spectroscopy and the detection of magnetofossils, J. R. Soc. Interface, 10(80), doi: 10.1098/rsif.2012.0790 [4] Kind J., van Raden U., Garcia-Rubio I., and Gehring A. U., 2012, Rock magnetic techniques complemented by ferromagnetic resonance spectroscopy to analyse a sediment record, Geophys. J. Int., 191, 51-61, doi: 10.1111/j.1365-246X.2012.05620.x

Quantum correlation properties in Matrix Product States of finite-number spin rings

NASA Astrophysics Data System (ADS)

Zhu, Jing-Min; He, Qi-Kai

2018-02-01

The organization and structure of quantum correlation (QC) of quantum spin-chains are very rich and complex. Hence the depiction and measures about the QC of finite-number spin rings deserved to be investigated intensively by using Matrix Product States(MPSs) in addition to the case with infinite-number. Here the dependencies of the geometric quantum discord(GQD) of two spin blocks on the total spin number, the spacing spin number and the environment parameter are presented in detail. We also compare the GQD with the total correlation(TC) and the classical correlation(CC) and illustrate its characteristics. Predictably, our findings may provide the potential of designing the optimal QC experimental detection proposals and pave the way for the designation of optimal quantum information processing schemes.

Intermittent many-body dynamics at equilibrium

NASA Astrophysics Data System (ADS)

Danieli, C.; Campbell, D. K.; Flach, S.

2017-06-01

The equilibrium value of an observable defines a manifold in the phase space of an ergodic and equipartitioned many-body system. A typical trajectory pierces that manifold infinitely often as time goes to infinity. We use these piercings to measure both the relaxation time of the lowest frequency eigenmode of the Fermi-Pasta-Ulam chain, as well as the fluctuations of the subsequent dynamics in equilibrium. The dynamics in equilibrium is characterized by a power-law distribution of excursion times far off equilibrium, with diverging variance. Long excursions arise from sticky dynamics close to q -breathers localized in normal mode space. Measuring the exponent allows one to predict the transition into nonergodic dynamics. We generalize our method to Klein-Gordon lattices where the sticky dynamics is due to discrete breathers localized in real space.

Nanopteron solutions of diatomic Fermi-Pasta-Ulam-Tsingou lattices with small mass-ratio

NASA Astrophysics Data System (ADS)

Hoffman, Aaron; Wright, J. Douglas

2017-11-01

Consider an infinite chain of masses, each connected to its nearest neighbors by a (nonlinear) spring. This is a Fermi-Pasta-Ulam-Tsingou lattice. We prove the existence of traveling waves in the setting where the masses alternate in size. In particular we address the limit where the mass ratio tends to zero. The problem is inherently singular and we find that the traveling waves are not true solitary waves but rather ;nanopterons;, which is to say, waves which are asymptotic at spatial infinity to very small amplitude periodic waves. Moreover, we can only find solutions when the mass ratio lies in a certain open set. The difficulties in the problem all revolve around understanding Jost solutions of a nonlocal Schrödinger operator in its semi-classical limit.

Protecting clean critical points by local disorder correlations

NASA Astrophysics Data System (ADS)

Hoyos, J. A.; Laflorencie, Nicolas; Vieira, André.; Vojta, Thomas

2011-03-01

We show that a broad class of quantum critical points can be stable against locally correlated disorder even if they are unstable against uncorrelated disorder. Although this result seemingly contradicts the Harris criterion, it follows naturally from the absence of a random-mass term in the associated order-parameter field theory. We illustrate the general concept with explicit calculations for quantum spin-chain models. Instead of the infinite-randomness physics induced by uncorrelated disorder, we find that weak locally correlated disorder is irrelevant. For larger disorder, we find a line of critical points with unusual properties such as an increase of the entanglement entropy with the disorder strength. We also propose experimental realizations in the context of quantum magnetism and cold-atom physics. Financial support: Fapesp, CNPq, NSF, and Research Corporation.

Interpenetrating and non-interpenetrating 3-dimensional coordination polymer frameworks from multiple building blocks

NASA Astrophysics Data System (ADS)

Bradshaw, Darren; Rosseinsky, Matthew J.

2005-12-01

Reaction of Co(NO3)2ṡ6H2O with the multidentate ligands benzene-1,3,5-tricarboxylate (btc) and the flexible bipyridyl ligand 1,2-bis(4-pyridyl)ethane (bpe) affords the 3-dimensional coordination polymers [Co3(btc)2(bpe)3(eg)2]ṡ(guests) 1, where eg = ethylene glycol, and [Co2(Hbtc)2(bpe)2]ṡ(bpe) 2. Both phases are comprised of infinite metal-carboxylate dimer chains, linked into 2-dimensional sheets by the bpe ligands. These sheets are further linked to adjacent sheets through covalent interactions, 1, or through hydrogen-bonding interactions, 2, to yield the 3-dimensional structures. Phase 1 exhibits solvent filled 1-dimensional pores, whereas 2 is triply-interpenetrated to form a dense solid array.

Microporous Materials of Metal Carboxylates

NASA Astrophysics Data System (ADS)

Mori, Wasuke; Takamizawa, Satoshi

2000-06-01

Copper(II) terephthalate absorbs a large amount of gases such as N2, Ar, O2, and Xe. The maximum amounts of absorption of gases were 1.8, 1.9, 2.2, and 0.9 mole per mole of the copper(II) salt for N2, Ar, O2, and Xe, respectively, indicating that the gases were not adsorbed on the surface but occluded within the solid. Other microporous copper(II) dicarboxylates are also reviewed. The porous structure of copper(II) terephthalate, in which the gas is occluded, is deduced from the temperature dependence of magnetic susceptibilities and the linear structure of terephthalate. Microporous molybdenum(II) and ruthenium(II, III) dicarboxylates are discussed. We describe that rhodium(II) monocarboxylate bridged by pyrazine form stable micropores by self-assembly of infinite linear chain complexes.

Using Crystal Structure Groups to Understand Mössbauer parameters of Ferric Sulfates

NASA Astrophysics Data System (ADS)

Knutson, J.; Dyar, M. D.; Sklute, E. C.; Lane, M. D.; Bishop, J. L.

2008-12-01

A Mössbauer doublet assigned to ferric sulfate (Fe3D2) was identified in Paso Robles, Mars, spectra by Morris et al. (2006), who noted that its parameters are not diagnostic of any specific mineral because a number of different sulfates with varying parageneses might be responsible for this doublet. Work by Lane et al. (2008) used a multi-instrument approach based on Fe3+ sulfate spectra acquired with VNIR and midinfrared reflectance, mid-infrared emission and Mössbauer spectrometers to narrow down the possible ferric sulfate phases present at Paso Robles to ferricopiapite possibly mixed with other ferric sulfates such as butlerite, parabutlerite, fibroferrite, or metahomanite. Thus, we explore here the crystal-chemical rationale behind these interpretations of the Mössbauer results, using similarities and difference among mineral structures to explore which phases might have similar coordination polyhedra around the Fe atoms in sulfates. Work by Hawthorne et al. (2000) organizes the sulfate minerals into groups with analogous crystal structures. Mössbauer doublets assigned to ferric sulfates ubiquitously have isomer shifts (IS) of 0.40-53 mm/s so that IS is non-diagnostic. However, quadrupole splitting of doublets in these mineral groups has a wide range (0-1.4 mm/s) and the variation can be systematically correlated with different structure types. Members of the hydration series Fe2(SO4)3 · n H2O, which includes quenstedtite, coquimbite, paracoquimbite, kornelite, and lausenite have Mössbauer spectra that closely resemble singlets because of their near-zero QS. These minerals share structures involving finite clusters of sulfate tetrahedral and Fe octahedral or chains of depolymerized clusters, and all mineral species with these structures share similar Mössbauer parameters. At the other extreme, ferric sulfates with structures based on infinite sheets (hydrotalcite, alunite, jarosite), tend to have large electric field gradients at the nucleus of the Fe3+ cation, resulting in larger QS values (1-1.4 mm/s). Between these extremes of QS are two populations of structures based on finite clusters of polyhedra with QS = 0.36-0.80 mm/s (coquimbite, römerite, halotrichite, rozenite) and infinite chains with QS = 0.70-0.97 mm/s (chalcanthite, butlerite, fibroferrite, metahomanite). Our fits to the Paso Robles sol 429A data show two ferric doublets, both with IS = 0.42-0.43 mm/s but with differing QS = 0.36 and 0.93 mm/s; these parameters rule out mineral structures that have spectra with very high or very low QS. Ferric sulfates with structures composed of finite clusters and infinite chains thus provide the closest matches to the Paso Robles Mössbauer doublets, as well as spectra of other bright soils. Further constraints provided by other types of spectroscopy are then needed to determine which species within these structure groups are present. As additional sulfate structures are characterized, it will be possible to better understand the interrelationships among sulfate crystal structures and their spectral characteristics may provide additional constraints on mineral identification from ferric materials of all types. Morris et al. (2006) JGR, 111, doi: 10.1029/2005JE002584. Lane et al. (2008) Amer. Mineral., 93, 738-739. Hawthorne et al. (2000) Revs. Mineral., 40, 1-112.

Point interactions, metamaterials, and PT-symmetry

NASA Astrophysics Data System (ADS)

Mostafazadeh, Ali

2016-05-01

We express the boundary conditions for TE and TM waves at the interfaces of an infinite planar slab of homogeneous metamaterial as certain point interactions and use them to compute the transfer matrix of the system. This allows us to demonstrate the omnidirectional reflectionlessness of Veselago's slab for waves of arbitrary wavelength, reveal the translational and reflection symmetry of this slab, explore the laser threshold condition and coherent perfect absorption for active negative-index metamaterials, introduce a point interaction modeling phase-conjugation, determine the corresponding antilinear transfer matrix, and offer a simple proof of the equivalence of Veselago's slab with a pair of parallel phase-conjugating plates. We also study the connection between certain optical setups involving metamaterials and a class of PT-symmetric quantum systems defined on wedge-shape contours in the complex plane. This provides a physical interpretation for the latter.

Induced Eddy Currents in Simple Conductive Geometries: Mathematical Formalism Describes the Excitation of Electrical Eddy Currents in a Time-Varying Magnetic Field

DOE PAGES

Nagel, James R.

2017-12-22

In this paper, a complete mathematical formalism is introduced to describe the excitation of electrical eddy currents due to a time-varying magnetic field. The process works by applying a quasistatic approximation to Ampere's law and then segregating the magnetic field into impressed and induced terms. The result is a nonhomogeneous vector Helmholtz equation that can be analytically solved for many practical geometries. Four demonstration cases are then solved under a constant excitation field over all space—an infinite slab in one dimension, a longitudinal cylinder in two dimensions, a transverse cylinder in two dimensions, and a sphere in three dimensions. Numericalmore » simulations are also performed in parallel with analytic computations, all of which verify the accuracy of the derived expressions.« less

Emission of Sound from Turbulence Convected by a Parallel Mean Flow in the Presence of a Confining Duct

NASA Technical Reports Server (NTRS)

Goldstein, Marvin E.; Leib, Stewart J.

1999-01-01

An approximate method for calculating the noise generated by a turbulent flow within a semi-infinite duct of arbitrary cross section is developed. It is based on a previously derived high-frequency solution to Lilley's equation, which describes the sound propagation in a transversely-sheared mean flow. The source term is simplified by assuming the turbulence to be axisymmetric about the mean flow direction. Numerical results are presented for the special case of a ring source in a circular duct with an axisymmetric mean flow. They show that the internally generated noise is suppressed at sufficiently large upstream angles in a hard walled duct, and that acoustic liners can significantly reduce the sound radiated in both the upstream and downstream regions, depending upon the source location and Mach number of the flow.

Emission of Sound From Turbulence Convected by a Parallel Mean Flow in the Presence of a Confining Duct

NASA Technical Reports Server (NTRS)

Goldstein, Marvin E.; Leib, Stewart J.

1999-01-01

An approximate method for calculating the noise generated by a turbulent flow within a semi-infinite duct of arbitrary cross section is developed. It is based on a previously derived high-frequency solution to Lilley's equation, which describes the sound propagation in transversely-sheared mean flow. The source term is simplified by assuming the turbulence to be axisymmetric about the mean flow direction. Numerical results are presented for the special case of a ring source in a circular duct with an axisymmetric mean flow. They show that the internally generated noise is suppressed at sufficiently large upstream angles in a hard walled duct, and that acoustic liners can significantly reduce the sound radiated in both the upstream and downstream regions, depending upon the source location and Mach number of the flow.

Thermocapillary convection in two immiscible liquid layers with free surface

NASA Technical Reports Server (NTRS)

Doi, Takao; Koster, Jean N.

1993-01-01

Thermocapillary convection is studied in two immiscible liquid layers with one free surface, one liquid/liquid interface, and differential heating applied parallel to the interfaces. An analytical solution is introduced for infinite horizontal layers. The defining parameter for the flow pattern is lambda, the ratio of the temperature coefficient of the interfacial tension to that of the surface tension. Four different flow patterns exist under zero gravity conditions. 'Halt' conditions which halt the fluid motion in the lower encapsulated liquid layer have been found. A numerical experiment is carried out to study effects of vertical end walls on the double layer convection in a 2D cavity. The halt condition obtained from the analytical study is found to be valid in the limit of small Reynolds numbers. The flow in the encapsulated liquid layer can be suppressed substantially.

Crystal structure of a new amine nitrate: 4-dimethylaminopyridinium nitrate (C{sub 7}H{sub 11}N{sub 2})NO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benhassan, D., E-mail: houcine-naili@yahoo.com; Rekik, W.; Naïli, H.

2015-12-15

The title compound (C{sub 7}H{sub 11}N{sub 2})NO{sub 3} (I) was obtained by the slow evaporation method at room temperature. Its crystal structure consists of organic cations (C{sub 7}H{sub 11}N{sub 2}){sup +} and nitrate anions (NO{sub 3}){sup –} linked by two types of hydrogen bonds. Each monoprotonated nitrogen atom, called bifurcated, is engaged in two N–H···O hydrogen bonds with two symmetric oxygen atoms. In addition, the crystal structure stability is established by C–H···O hydrogen bonds that ensure the formation of infinite layers, parallel to (001) plane. These layers are related together through π···π interactions established between aromatic amines.

Couette flow of an incompressible fluid in a porous channel with mass transfer

NASA Astrophysics Data System (ADS)

Niranjana, N.; Vidhya, M.; Govindarajan, A.

2018-04-01

The present discussion deals with the study of couette flow through a porous medium of a viscous incompressible fluid between two infinite horizontal parallel porous flat plates with heat and mass transfer. The stationary plate and the plate in uniform motion are subjected to transverse sinusoidal injection and uniform suction of the fluid. Due to this type of injection velocity, the flow becomes three dimensional. The analytical solutions of the nonlinear partial differential equations of this problem are obtained by using perturbation technique. Expressions for the velocity, temperature fields and the rate of heat and mass transfers are obtained. Effects of the following parameters Schmidt number (Sc), Modified Grashof number (Gm) on the velocity, temperature and concentration fields are obtained numerically and depicted through graphs. The rate of heat and mass transfer are also analyzed.

Induced Eddy Currents in Simple Conductive Geometries: Mathematical Formalism Describes the Excitation of Electrical Eddy Currents in a Time-Varying Magnetic Field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagel, James R.

In this paper, a complete mathematical formalism is introduced to describe the excitation of electrical eddy currents due to a time-varying magnetic field. The process works by applying a quasistatic approximation to Ampere's law and then segregating the magnetic field into impressed and induced terms. The result is a nonhomogeneous vector Helmholtz equation that can be analytically solved for many practical geometries. Four demonstration cases are then solved under a constant excitation field over all space—an infinite slab in one dimension, a longitudinal cylinder in two dimensions, a transverse cylinder in two dimensions, and a sphere in three dimensions. Numericalmore » simulations are also performed in parallel with analytic computations, all of which verify the accuracy of the derived expressions.« less

Accelerated sampling by infinite swapping of path integral molecular dynamics with surface hopping

NASA Astrophysics Data System (ADS)

Lu, Jianfeng; Zhou, Zhennan

2018-02-01

To accelerate the thermal equilibrium sampling of multi-level quantum systems, the infinite swapping limit of a recently proposed multi-level ring polymer representation is investigated. In the infinite swapping limit, the ring polymer evolves according to an averaged Hamiltonian with respect to all possible surface index configurations of the ring polymer and thus connects the surface hopping approach to the mean-field path-integral molecular dynamics. A multiscale integrator for the infinite swapping limit is also proposed to enable efficient sampling based on the limiting dynamics. Numerical results demonstrate the huge improvement of sampling efficiency of the infinite swapping compared with the direct simulation of path-integral molecular dynamics with surface hopping.

The infinite limit as an eliminable approximation for phase transitions

NASA Astrophysics Data System (ADS)

Ardourel, Vincent

2018-05-01

It is generally claimed that infinite idealizations are required for explaining phase transitions within statistical mechanics (e.g. Batterman 2011). Nevertheless, Menon and Callender (2013) have outlined theoretical approaches that describe phase transitions without using the infinite limit. This paper closely investigates one of these approaches, which consists of studying the complex zeros of the partition function (Borrmann et al., 2000). Based on this theory, I argue for the plausibility for eliminating the infinite limit for studying phase transitions. I offer a new account for phase transitions in finite systems, and I argue for the use of the infinite limit as an approximation for studying phase transitions in large systems.

A computer model of molecular arrangement in a n-paraffinic liquid

NASA Astrophysics Data System (ADS)

Vacatello, Michele; Avitabile, Gustavo; Corradini, Paolo; Tuzi, Angela

1980-07-01

A computer model of a bulk liquid polymer was built to investigate the problem of local order. The model is made of C30 n-alkane molecules; it is not a lattice model, but it allows for a continuous variability of torsion angles and interchain distances, subject to realistic intra- and intermolecular potentials. Experimental x-ray scattering curves and radial distribution functions are well reproduced. Calculated properties like end-to-end distances, distribution of torsion angles, radial distribution functions, and chain direction correlation parameters, all indicate a random coil conformation and no tendency to form bundles of parallel chains.

Interest of new communicating material paradigm: An attempt in wood industry

NASA Astrophysics Data System (ADS)

Jover, J.; Thomas, A.; Leban, J. M.; Canet, D.

2013-03-01

This paper present a new paradigm in which the wood material could become communicating. We decide to use Nuclear Quadrupole Resonance to mass marking the wood. We imagine a new method to create identification codes. At first, we examine the feasibility of this mass marking method by impregnating wood to obtain a specific marking signal. In parallel, we study the interest to abide information provided by this marker to control the supply chain. We model the supply chain (e.g. the information/decisional flow) to understand which information is important and how to use it.

New species from the Galoka and Kalabenono massifs: two unknown and severely threatened mountainous areas in NW Madagascar

PubMed Central

Callmander, Martin W.; Rakotovao, Charles; Razafitsalama, Jeremi; Phillipson, Peter B.; Buerki, Sven; Hong-Wa, Cynthia; Rakotoarivelo, Nivo; Andriambololonera, Sylvie; Koopman, Margaret M.; Johnson, David M.; Deroin, Thierry; Ravoahangy, Andriamandranto; Solo, Serge; Labat, Jean-Noël; Lowry, Porter P.

2011-01-01

The Galoka mountain chain, comprising principally the Galoka and Kalabenono massifs, situated at the northern edge of the Sambirano Region in NW Madagascar is an area that was virtually unknown botanically. It was visited three times between 2005 and 2007 as part of a floristic inventory. Both massifs contain the last remaining primary forests in the Galoka chain, which extends parallel to the coastline from South of Ambilobe to North of Ambanja. Several new species have been discovered amongst the collections, eight of which are described here. PMID:21857767

Inverse relaxation effect of azo-dye molecules: The role of the film anisotropy

NASA Astrophysics Data System (ADS)

Sehnem, A. L.; Faita, F. L.; Cabrera, F. C.; Job, A. E.; Bechtold, I. H.

2013-11-01

We investigated the effect generally treated in the literature as inverse relaxation, which is related to an increase in the birefringence of azopolymer films after the inscription laser is turned off. The results demonstrate that films prepared with the casting method on anisotropic substrates induce a preferential organization of the polymeric chains. Inverse relaxation is evidenced only when the photo-alignment of the azo groups is induced parallel to the orientation of the polymeric chains. Thus, it is possible to enhance the optical storage in these systems with appropriate alignment methods.

Microfluidic integration of parallel solid-phase liquid chromatography.

PubMed

Huft, Jens; Haynes, Charles A; Hansen, Carl L

2013-03-05

We report the development of a fully integrated microfluidic chromatography system based on a recently developed column geometry that allows for robust packing of high-performance separation columns in poly(dimethylsiloxane) microfluidic devices having integrated valves made by multilayer soft lithography (MSL). The combination of parallel high-performance separation columns and on-chip plumbing was used to achieve a fully integrated system for on-chip chromatography, including all steps of automated sample loading, programmable gradient generation, separation, fluorescent detection, and sample recovery. We demonstrate this system in the separation of fluorescently labeled DNA and parallel purification of reverse transcription polymerase chain reaction (RT-PCR) amplified variable regions of mouse immunoglobulin genes using a strong anion exchange (AEX) resin. Parallel sample recovery in an immiscible oil stream offers the advantage of low sample dilution and high recovery rates. The ability to perform nucleic acid size selection and recovery on subnanogram samples of DNA holds promise for on-chip genomics applications including sequencing library preparation, cloning, and sample fractionation for diagnostics.

Quantum Markov chains, sufficiency of quantum channels, and Rényi information measures

NASA Astrophysics Data System (ADS)

Datta, Nilanjana; Wilde, Mark M.

2015-12-01

A short quantum Markov chain is a tripartite state {ρ }{ABC} such that system A can be recovered perfectly by acting on system C of the reduced state {ρ }{BC}. Such states have conditional mutual information I(A;B| C) equal to zero and are the only states with this property. A quantum channel {N} is sufficient for two states ρ and σ if there exists a recovery channel using which one can perfectly recover ρ from {N}(ρ ) and σ from {N}(σ ). The relative entropy difference D(ρ \\parallel σ )-D({N}(ρ )\\parallel {N}(σ )) is equal to zero if and only if {N} is sufficient for ρ and σ. In this paper, we show that these properties extend to Rényi generalizations of these information measures which were proposed in (Berta et al 2015 J. Math. Phys. 56 022205; Seshadreesan et al 2015 J. Phys. A: Math. Theor. 48 395303), thus providing an alternate characterization of short quantum Markov chains and sufficient quantum channels. These results give further support to these quantities as being legitimate Rényi generalizations of the conditional mutual information and the relative entropy difference. Along the way, we solve some open questions of Ruskai and Zhang, regarding the trace of particular matrices that arise in the study of monotonicity of relative entropy under quantum operations and strong subadditivity of the von Neumann entropy.

Valence-bond theory of linear Hubbard and Pariser-Parr-Pople models

NASA Astrophysics Data System (ADS)

Soos, Z. G.; Ramasesha, S.

1984-05-01

The ground and low-lying states of finite quantum-cell models with one state per site are obtained exactly through a real-space basis of valence-bond (VB) diagrams that explicitly conserve the total spin. Regular and alternating Hubbard and Pariser-Parr-Pople (PPP) chains and rings with Ne electrons on N(<=12) sites are extrapolated to infinite arrays. The ground-state energy and optical gap of regular U=4|t| Hubbard chains agree with exact results, suggesting comparable accuracy for alternating Hubbard and PPP models, but differ from mean-field results. Molecular PPP parameters describe well the excitations of finite polyenes, odd polyene ions, linear cyanine dyes, and slightly overestimate the absorption peaks in polyacetylene (CH)x. Molecular correlations contrast sharply with uncorrelated descriptions of topological solitons, which are modeled by regular polyene radicals and their ions for both wide and narrow alternation crossovers. Neutral solitons have no midgap absorption and negative spin densities, while the intensity of the in-gap excitation of charged solitons is not enhanced. The properties of correlated states in quantum-cell models with one valence state per site are discussed in the adiabatic limit for excited-state geometries and instabilities to dimerization.

New process of preparation, X-ray characterisation, structure and vibrational studies of a solid solution LiTiOAs 1-xP xO 4 (0⩽ x⩽1)

NASA Astrophysics Data System (ADS)

Chakir, M.; El Jazouli, A.; Chaminade, J. P.; Bouree, F.; de Waal, D.

2006-01-01

LiTiOAs 1-xP xO 4 (0⩽ x⩽1) compounds have been prepared using solutions of Li, Ti, As and P elements as starting products. Selected compositions have been investigated by powder X-ray or neutrons diffraction analysis, Raman and infrared spectroscopy. The structure of LiTiOAs 1-xP xO 4 ( x=0, 0.5 and 1) samples determined by Rietveld analysis is orthorhombic with Pnma space group. It is formed by a 3D network of TiO 6 octahedra and XO 4 ( X=As 1-xP x) tetrahedra where octahedral cavities are occupied by lithium atoms. TiO 6 octahedra are linked together by corners and form infinite chains along a-axis. Ti atoms are displaced from the centre of octahedral units in alternating short (1.700-1.709 Å) and long (2.301-2.275 Å) Ti-O bonds. Raman and infrared studies confirm the existence of Ti-O-Ti chains. Thermal stability of LiTiOAsO 4 has been reported.

Different water clusters dependent on long-chain dicarboxylates in two Ag(I) coordination polymers: Synthesis, structure and thermal stability

NASA Astrophysics Data System (ADS)

Sun, Di; Liu, Fu-Jing; Hao, Hong-Jun; Huang, Rong-Bin; Zheng, Lan-Sun

2011-10-01

Two mixed-ligand Ag(I) coordination polymers (CPs), [Ag 2(bipy) 2(sub)·5H 2O] n ( 1), [Ag 2(bipy) 2(aze)·3H 2O] n ( 2), (bipy = 4,4'-bipyridine, H 2sub = suberic acid, H 2aze = azelaic acid) have been synthesized and structurally characterized by elemental analysis, infrared (IR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric (TG) analysis, and single crystal X-ray diffraction. Both 1 and 2 are two-dimensional (2D) sheets based on infinite [Ag(bipy)] n double chain incorporating Ag⋯Ag interactions. Interestingly, two different water clusters are encapsulated in the voids between the sheets of 1 and 2. For 1, one water decamer (H 2O) 10 based on a cyclic water tetramer was hydrogen-bonded with the host 2D sheet. While, one water hexamer (H 2O) 6 also based on a cyclic water tetramer was observed in 2. Comparing the experimental results, it is comprehensible that the dicarboxylates play a crucial role in the formation of the different water clusters. Moreover, the thermal stabilities of them were also discussed.

Structurally complex Zintl compounds for high temperature thermoelectric power generation

NASA Astrophysics Data System (ADS)

Zevalkink, Alexandra; Pomrehn, Gregory; Gibbs, Zachary; Snyder, Jeffrey

2014-03-01

Zintl phases, characterized by covalently-bonded substructures surrounded by highly electropositive cations, exhibit many of the characteristics desired for thermoelectric applications. Recently, we demonstrated promising thermoelectric performance (zT values between 0.4 and 0.9) in a class of Zintl antimonides that share a common structural motif: anionic moieties resembling infinite chains of linked tetrahedra. These compounds (A5M2 Sb6 and A3 M Sb3 compounds where A = Ca or Sr and M = Al, Ga and In) crystallize as four distinct, but closely related chain-forming structure types. Their large unit cells lead to exceptionally low lattice thermal conductivity due to the containment of heat in low velocity optical phonon modes. Here, we show that chemical substitutions on the A and M sites can be used to control the electronic and thermal transport properties and optimize the thermoelectric figure of merit. Doping with alio-valent elements allows for rational control of the carrier concentration, while isoelectronic substitutions can be used to fine-tune the intrinsic properties. A combination of Density Functional calculations and classical transport models was used to explain the experimentally observed transport properties of these compounds.

Four unprecedented cobalt(II) and cadmium(II) metal-organic frameworks based on a rigid tricarboxylate ligand: Synthesis, crystal structures, magnetic and fluorescence properties

NASA Astrophysics Data System (ADS)

Liu, Yaru; Liu, Lan; Zhang, Xiao; Wu, Jie

2018-03-01

A Co(II) MOF {[Co3(L)2(H2O)4](DMF)2}n (1) and three Cd(II) MOFs [Cd3(L)2(H2O)7]n (2), [Cd3(L)2(H2O)11]n (3) and [Cd3(L)2(DMF)2(H2O)]n (4) are synthesized based on the promising multifunctional tricarboxylate ligand 6-(3, 5-dicarboxyl phenyl) nicotinic acid (H3L). 1 exhibits a 3D framework with 1D channels which contains opposite-handedness helical chains based on the trinuclear Co(II) clusters. 2-4 are obtained depend on different reaction conditions. 2 displays a 3D framework, which is composed of two kinds of 2D layers linked with each other. 3 shows a rare tongue-and-groove-type bilayer structure. And 4 is an interesting 3D framework containing infinite 1D inorganic Cdsbnd Osbnd Cd chains. In these MOFs, the H3L ligand shows the versatile coordination modes and strong coordination ability. Furthermore, the magnetic and solid-state luminescent properties of the MOFs have been investigated.

Crystal structure of fac-tri-carbonyl-chlorido-bis-(4-hy-droxy-pyridine)-rhenium(I)-pyridin-4(1H)-one (1/1).

PubMed

Argibay-Otero, Saray; Carballo, Rosa; Vázquez-López, Ezequiel M

2017-10-01

The asymmetric unit of the title compound, [ReCl(C 5 H 5 NO) 2 (CO) 3 ]·C 5 H 5 NO, contains one mol-ecule of the complex fac -[ReCl(4-pyOH) 2 (CO) 3 ] (where 4-pyOH represents 4-hy-droxy-pyridine) and one mol-ecule of pyridin-4(1 H )-one (4-HpyO). In the mol-ecule of the complex, the Re atom is coordinated to two N atoms of the two 4-pyOH ligands, three carbonyl C atoms, in a facial configuration, and the Cl atom. The resulting geometry is slightly distorted octa-hedral. In the crystal structure, both fragments are associated by hydrogen bonds; two 4-HpyO mol-ecules bridge between two mol-ecules of the complex using the O=C group as acceptor for two different HO- groups of coordinated 4-pyOH from two neighbouring metal complexes. The resulting square arrangements are extented into infinite chains by hydrogen bonds involving the N-H groups of the 4-HpyO mol-ecule and the chloride ligands. The chains are further stabilized by π-stacking inter-actions.

Model of directed lines for square ice with second-neighbor and third-neighbor interactions

NASA Astrophysics Data System (ADS)

Kirov, Mikhail V.

2018-02-01

The investigation of the properties of nanoconfined systems is one of the most rapidly developing scientific fields. Recently it has been established that water monolayer between two graphene sheets forms square ice. Because of the energetic disadvantage, in the structure of the square ice there are no longitudinally arranged molecules. The result is that the structure is formed by unidirectional straight-lines of hydrogen bonds only. A simple but accurate discrete model of square ice with second-neighbor and third-neighbor interactions is proposed. According to this model, the ground state includes all configurations which do not contain three neighboring unidirectional chains of hydrogen bonds. Each triplet increases the energy by the same value. This new model differs from an analogous model with long-range interactions where in the ground state all neighboring chains are antiparallel. The new model is suitable for the corresponding system of point electric (and magnetic) dipoles on the square lattice. It allows separately estimating the different contributions to the total binding energy and helps to understand the properties of infinite monolayers and finite nanostructures. Calculations of the binding energy for square ice and for point dipole system are performed using the packages TINKER and LAMMPS.

ASSET: Analysis of Sequences of Synchronous Events in Massively Parallel Spike Trains

PubMed Central

Canova, Carlos; Denker, Michael; Gerstein, George; Helias, Moritz

2016-01-01

With the ability to observe the activity from large numbers of neurons simultaneously using modern recording technologies, the chance to identify sub-networks involved in coordinated processing increases. Sequences of synchronous spike events (SSEs) constitute one type of such coordinated spiking that propagates activity in a temporally precise manner. The synfire chain was proposed as one potential model for such network processing. Previous work introduced a method for visualization of SSEs in massively parallel spike trains, based on an intersection matrix that contains in each entry the degree of overlap of active neurons in two corresponding time bins. Repeated SSEs are reflected in the matrix as diagonal structures of high overlap values. The method as such, however, leaves the task of identifying these diagonal structures to visual inspection rather than to a quantitative analysis. Here we present ASSET (Analysis of Sequences of Synchronous EvenTs), an improved, fully automated method which determines diagonal structures in the intersection matrix by a robust mathematical procedure. The method consists of a sequence of steps that i) assess which entries in the matrix potentially belong to a diagonal structure, ii) cluster these entries into individual diagonal structures and iii) determine the neurons composing the associated SSEs. We employ parallel point processes generated by stochastic simulations as test data to demonstrate the performance of the method under a wide range of realistic scenarios, including different types of non-stationarity of the spiking activity and different correlation structures. Finally, the ability of the method to discover SSEs is demonstrated on complex data from large network simulations with embedded synfire chains. Thus, ASSET represents an effective and efficient tool to analyze massively parallel spike data for temporal sequences of synchronous activity. PMID:27420734

Adsorption of 1- and 2-butylimidazoles at the copper/air and steel/air interfaces studied by sum frequency generation vibrational spectroscopy.

PubMed

Casford, Michael T L; Davies, Paul B

2012-07-24

The structure of thin films of 1- and 2-butylimidazoles adsorbed on copper and steel surfaces under air was examined using sum frequency generation (SFG) vibrational spectroscopy in the ppp and ssp polarizations. Additionally, the SFG spectra of both isomers were recorded at 55 °C at the liquid imidazole/air interface for reference. Complementary bulk infrared, reflection-absorption infrared spectroscopy (RAIRS), and Raman spectra of both imidazoles were recorded for assignment purposes. The SFG spectra in the C-H stretching region at the liquid/air interface are dominated by resonances from the methyl end group of the butyl side chain of the imidazoles, indicating that they are aligned parallel or closely parallel to the surface normal. These are also the most prominent features in the SFG spectra on copper and steel. In addition, both the ppp and ssp spectra on copper show resonances from the C-H stretching modes of the imidazole ring for both isomers. The ring C-H resonances are completely absent from the spectra on steel and at the liquid/air interface. The relative intensities of the SFG spectra can be interpreted as showing that, on copper, under air, both butylimidazoles are adsorbed with their butyl side chains perpendicular to the interface and with the ring significantly inclined away from the surface plane and toward the surface normal. The SFG spectra of both imidazoles on steel indicate an orientation where the imidazole rings are parallel or nearly parallel to the surface. The weak C-H resonances from the ring at the liquid/air interface suggest that the tilt angle of the ring from the surface normal at this interface is significantly greater than it is on copper.

The Metropolis Monte Carlo method with CUDA enabled Graphic Processing Units

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, Clifford; School of Physics, Astronomy, and Computational Sciences, George Mason University, 4400 University Dr., Fairfax, VA 22030; Ji, Weixiao

2014-02-01

We present a CPU–GPU system for runtime acceleration of large molecular simulations using GPU computation and memory swaps. The memory architecture of the GPU can be used both as container for simulation data stored on the graphics card and as floating-point code target, providing an effective means for the manipulation of atomistic or molecular data on the GPU. To fully take advantage of this mechanism, efficient GPU realizations of algorithms used to perform atomistic and molecular simulations are essential. Our system implements a versatile molecular engine, including inter-molecule interactions and orientational variables for performing the Metropolis Monte Carlo (MMC) algorithm,more » which is one type of Markov chain Monte Carlo. By combining memory objects with floating-point code fragments we have implemented an MMC parallel engine that entirely avoids the communication time of molecular data at runtime. Our runtime acceleration system is a forerunner of a new class of CPU–GPU algorithms exploiting memory concepts combined with threading for avoiding bus bandwidth and communication. The testbed molecular system used here is a condensed phase system of oligopyrrole chains. A benchmark shows a size scaling speedup of 60 for systems with 210,000 pyrrole monomers. Our implementation can easily be combined with MPI to connect in parallel several CPU–GPU duets. -- Highlights: •We parallelize the Metropolis Monte Carlo (MMC) algorithm on one CPU—GPU duet. •The Adaptive Tempering Monte Carlo employs MMC and profits from this CPU—GPU implementation. •Our benchmark shows a size scaling-up speedup of 62 for systems with 225,000 particles. •The testbed involves a polymeric system of oligopyrroles in the condensed phase. •The CPU—GPU parallelization includes dipole—dipole and Mie—Jones classic potentials.« less

Synthesis, crystal structure, and magnetic properties of two-dimensional divalent metal glutarate/dipyridylamine coordination polymers, with a single crystal-to-single crystal transformation in the copper derivative

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montney, Matthew R.; Supkowski, Ronald M.; Staples, Richard J.

Hydrothermal reaction of divalent metal chlorides with glutaric acid and 4,4'-dipyridylamine (dpa) has afforded an isostructural family of coordination polymers with formulation [M(glu)(dpa)]{sub n} (M=Co (1), Ni (2), Cu (3); glu=glutarate). Square pyramidal coordination is seen in 1-3, with semi-ligation of a sixth donor to produce a '5+1' extended coordination sphere. Neighboring metal atoms are linked into 1D [M(glu)]{sub n} neutral chains through chelating/monodentate bridging glutarate moieties with a syn-anti binding mode, and semi-chelation of the pendant carboxylate oxygen. These chains further connect into 2D layers through dipodal dpa ligands. Neighboring layers stack into the pseudo 3D crystal structure ofmore » 1-3 through supramolecular hydrogen bonding between dpa amine units and the semi-chelated glutarate oxygen atoms. The variable temperature magnetic behavior of 1-3 was explored and modeled as infinite 1D Heisenberg chains. Notably, complex 3 undergoes a thermally induced single crystal-to-single crystal transformation between centric and acentric space groups, with a conformationally disordered unilayer structure at 293 K and an ordered bilayer structure at 173 K. All materials were further characterized via infrared spectroscopy and elemental and thermogravimetric analyses. - Graphical abstract: The coordination polymers [M(glu)(dpa)]{sub n} (M=Co (1), Ni (2), Cu (3); glu=glutarate, dpa=4,4'-dipyridylamine) exhibit 2D layer structures based on 1D [M(glu)]{sub n} chains linked through dpa tethers. Antiferromagnetic coupling is observed for 2 and 3, while ferromagnetism is predominant in 1. Compound 3 undergoes a thermally induced single crystal-to-single crystal transformation from an acentric to a centrosymmetric space group.« less

Integrability of conformal fishnet theory

NASA Astrophysics Data System (ADS)

Gromov, Nikolay; Kazakov, Vladimir; Korchemsky, Gregory; Negro, Stefano; Sizov, Grigory

2018-01-01

We study integrability of fishnet-type Feynman graphs arising in planar four-dimensional bi-scalar chiral theory recently proposed in arXiv:1512.06704 as a special double scaling limit of gamma-deformed N = 4 SYM theory. We show that the transfer matrix "building" the fishnet graphs emerges from the R-matrix of non-compact conformal SU(2 , 2) Heisenberg spin chain with spins belonging to principal series representations of the four-dimensional conformal group. We demonstrate explicitly a relationship between this integrable spin chain and the Quantum Spectral Curve (QSC) of N = 4 SYM. Using QSC and spin chain methods, we construct Baxter equation for Q-functions of the conformal spin chain needed for computation of the anomalous dimensions of operators of the type tr( ϕ 1 J ) where ϕ 1 is one of the two scalars of the theory. For J = 3 we derive from QSC a quantization condition that fixes the relevant solution of Baxter equation. The scaling dimensions of the operators only receive contributions from wheel-like graphs. We develop integrability techniques to compute the divergent part of these graphs and use it to present the weak coupling expansion of dimensions to very high orders. Then we apply our exact equations to calculate the anomalous dimensions with J = 3 to practically unlimited precision at any coupling. These equations also describe an infinite tower of local conformal operators all carrying the same charge J = 3. The method should be applicable for any J and, in principle, to any local operators of bi-scalar theory. We show that at strong coupling the scaling dimensions can be derived from semiclassical quantization of finite gap solutions describing an integrable system of noncompact SU(2 , 2) spins. This bears similarities with the classical strings arising in the strongly coupled limit of N = 4 SYM.

Yb5Ga2Sb6: a mixed valent and narrow-band gap material in the RE5M2X6 family.

PubMed

Subbarao, Udumula; Sarkar, Sumanta; Gudelli, Vijay Kumar; Kanchana, V; Vaitheeswaran, G; Peter, Sebastian C

2013-12-02

A new compound Yb5Ga2Sb6 was synthesized by the metal flux technique as well as high frequency induction heating. Yb5Ga2Sb6 crystallizes in the orthorhombic space group Pbam (no. 55), in the Ba5Al2Bi6 structure type, with a unit cell of a = 7.2769(2) Å, b = 22.9102(5) Å, c = 4.3984(14) Å, and Z = 2. Yb5Ga2Sb6 has an anisotropic structure with infinite anionic double chains (Ga2Sb6)(10-) cross-linked by Yb(2+) and Yb(3+) ions. Each single chain is made of corner-sharing GaSb4 tetrahedra. Two such chains are bridged by Sb2 groups to form double chains of 1/∞ [Ga2Sb6(10-)]. The compound satisfies the classical Zintl-Klemm concept and is a narrow band gap semiconductor with an energy gap of around 0.36 eV calculated from the electrical resistivity data corroborating with the experimental absorption studies in the IR region (0.3 eV). Magnetic measurements suggest Yb atoms in Yb5Ga2Sb6 exist in the mixed valent state. Temperature dependent magnetic susceptibility data follows the Curie-Weiss behavior above 100 K and no magnetic ordering was observed down to 2 K. Experiments are accompanied by all electron full-potential linear augmented plane wave (FP-LAPW) calculations based on density functional theory to calculate the electronic structure and density of states. The calculated band structure shows a weak overlap of valence band and conduction band resulting in a pseudo gap in the density of states revealing semimetallic character.

Stretching of Single Polymer Chains Using the Atomic Force Microscope

NASA Astrophysics Data System (ADS)

Ortiz, C.; van der Vegte, E. W.; van Swieten, E.; Robillard, G. T.; Hadziioannou, G.

1998-03-01

A variety of macroscopic phenomenon involve "nanoscale" polymer deformation including rubber elasticity, shear yielding, strain hardening, stress relaxation, fracture, and flow. With the advent of new and improved experimental techniques, such as the atomic force microscope (AFM), the probing of physical properties of polymers has reached finer and finer scales. The development of mixed self-assembling monolayer techniques and the chemical functionalization of AFM probe tips has allowed for mechanical experiments on single polymer chains of molecular dimensions. In our experiments, mixed monolayers are prepared in which end-functionalized, flexible polymer chains of thiol-terminated poly(methacrylic acid) are covalently bonded, isolated, and randomly distributed on gold substrates. The coils are then imaged, tethered to a gold-coated AFM tip, and stretched between the tip and the substrate in a conventional force / distance experiment. An increase in the attractive force due to entropic, elastic resistance to stretching, as well as fracture of the polymer chain is observed. The effect of chain stiffness, topological constraints, strain rate, mechanical hysteresis, and stress relaxation were investigated. Force modulation techniques were also employed in order to image the viscoelastic character of the polymer chains. Parallel work includes similar studies of biological systems such as wheat gluten proteins and polypeptides.

Low bias negative differential conductance and reversal of current in coupled quantum dots in different topological configurations

NASA Astrophysics Data System (ADS)

Devi, Sushila; Brogi, B. B.; Ahluwalia, P. K.; Chand, S.

2018-06-01

Electronic transport through asymmetric parallel coupled quantum dot system hybridized between normal leads has been investigated theoretically in the Coulomb blockade regime by using Non-Equilibrium Green Function formalism. A new decoupling scheme proposed by Rabani and his co-workers has been adopted to close the chain of higher order Green's functions appearing in the equations of motion. For resonant tunneling case; the calculations of current and differential conductance have been presented during transition of coupled quantum dot system from series to symmetric parallel configuration. It has been found that during this transition, increase in current and differential conductance of the system occurs. Furthermore, clear signatures of negative differential conductance and negative current appear in series case, both of which disappear when topology of system is tuned to asymmetric parallel configuration.

The Cognitive Architecture for Chaining of Two Mental Operations

ERIC Educational Resources Information Center

Sackur, Jerome; Dehaene, Stanislas

2009-01-01

A simple view, which dates back to Turing, proposes that complex cognitive operations are composed of serially arranged elementary operations, each passing intermediate results to the next. However, whether and how such serial processing is achieved with a brain composed of massively parallel processors, remains an open question. Here, we study…

4-[(3-Chloro-2-methyl-phen-yl)imino-meth-yl]phenol.

PubMed

Manjunath, B C; Abdoh, M M M; Mallesha, L; Mohana, K N; Lokanath, N K

2012-11-01

In the title compound, C(14)H(12)ClNO, the dihedral angle between the aromatic rings is 39.84 (7)°. In th crystal, mol-ecules are connected by O-H⋯N hydrogen bonds into chains parallel to [001]. In addition, a C-H⋯π contact occurs.

Wood

Treesearch

David W. Green; Robert H. White; Antoni TenWolde; William Simpson; Joseph Murphy; Robert J. Ross; Roland Hernandez; Stan T. Lebow

2006-01-01

Wood is a naturally formed organic material consisting essentially of elongated tubular elements called cells arranged in a parallel manner for the most part. These cells vary in dimensions and wall thickness with position in the tree, age, conditions of growth, and kind of tree. The walls of the cells are formed principally of chain molecules of cellulose, polymerized...

Crystal structure, magnetism, and luminescent properties of two isostructural pcu MOFs based on a triangular ligand

NASA Astrophysics Data System (ADS)

Yan, Pen-Ji; Yao, Xiao-Qiang; Xie, Hua; Xiao, Guo-Bin; Liu, Jia-Cheng; Xu, Xin-Jian

2018-05-01

Two isomorphous metal-organic frameworks, {[M(TIPA) (btec)½]H2O}n, [M = Co (1) or Zn (2)] were synthesized hydrothermally based on a semi-rigid N-center triangular ligand TIPA, where TIPA = tris(4-(1H-imidazol-1-yl)-phenyl)amine, H4btec = 1,2,4,5-benzenetetracarboxylic acid. Single crystal structural analyses show that complexes 1 and 2 are isostructural and both feature a twofold interpenetrated pcu topology. In 1 and 2, the btec4- ligand adopting μ2-η2:η1 and μ1-η1:η0 coordination modes connect adjacent dinuclear Co/Zn units to form a 1D straight polymeric chain. Then these chains arranged in parallel/parallel fashion were further extended to a 3D network by exo-tridentate ligand TIPA with μ2-κ2N:N‧ coordination mode. The magnetic property of 1 and the luminescent property of 2 were investigated. Furthermore, the structure and spectroscopic property of 2 were further investigated by DFT and TD-DFT calculations.

Infinity: The Twilight Zone of Mathematics.

ERIC Educational Resources Information Center

Love, William P.

1989-01-01

The theorems and proofs presented are designed to enhance student understanding of the theory of infinity as developed by Cantor and others. Three transfinite numbers are defined to express the cardinality of infinite algebraic sets, infinite sets of geometric points and infinite sets of functions. (DC)

Generalized analytic solutions and response characteristics of magnetotelluric fields on anisotropic infinite faults

NASA Astrophysics Data System (ADS)

Bing, Xue; Yicai, Ji

2018-06-01

In order to understand directly and analyze accurately the detected magnetotelluric (MT) data on anisotropic infinite faults, two-dimensional partial differential equations of MT fields are used to establish a model of anisotropic infinite faults using the Fourier transform method. A multi-fault model is developed to expand the one-fault model. The transverse electric mode and transverse magnetic mode analytic solutions are derived using two-infinite-fault models. The infinite integral terms of the quasi-analytic solutions are discussed. The dual-fault model is computed using the finite element method to verify the correctness of the solutions. The MT responses of isotropic and anisotropic media are calculated to analyze the response functions by different anisotropic conductivity structures. The thickness and conductivity of the media, influencing MT responses, are discussed. The analytic principles are also given. The analysis results are significant to how MT responses are perceived and to the data interpretation of the complex anisotropic infinite faults.

Synthesis and characterization of two novel inorganic/organic hybrid materials based on polyoxomolybdate clusters: (C5H5N5)2(C5H6N5)4[(HAsO4)2Mo6O18]·11H2O and Na2(Himi)3[SeMo6O21(CH3COO)3]·6H2O

NASA Astrophysics Data System (ADS)

Ayed, Meriem; Mestiri, Imen; Ayed, Brahim; Haddad, Amor

2017-01-01

Two new organic-inorganic hybrid compound, (C5H5N5)2(C5H6N5)4[(HAsO4)2Mo6O18]·11H2O (I) and Na2(Himi)3[SeMo6O21(CH3COO)3]·6H2O (II) were synthesized and structurally characterized by scanning electron microscopy (SEM), elemental analyses, FTIR, UV spectroscopy, thermal stability analysis, XRD and single crystal X-ray diffraction. Crystal data: (I) triclinic system, space group P-1, a = 11,217 (9) Å, b = 11,637 (8) Å, c = 14,919 (8) Å, α = 70,90 (5)°, β = 70,83 (2)°, γ = 62,00(1)° and Z = 1; (II) triclinic system, space group P-1, a = 10.6740(1) Å, b = 10.6740(1) Å, c = 20.0570(1) Å, α = 76.285(1)°, β = 82.198(2)°, γ = 87.075(1)°, Z = 1. The crystal structure of (I) can be described by infinite polyanions [(HAsO4)2Mo6O18]4- organized with water molecules in layers parallel to the c-direction; adjacent layers are further joined up by hydrogen bonding interactions with organic groups which were associated in chains spreading along the b-direction. The structure of (II) consists of functionalized selenomolybdate clusters [SeMo6O21(CH3COO)3]5-, protonated imidazole cations, sodium ions and lattice water molecules, which are held together to generate a three-dimensional supramolecular network via hydrogen-bonding interaction. Furthermore, the electrochemical properties of these compounds have been studied.

Electrostatic persistence length.

PubMed

Fixman, Marshall

2010-03-11

The persistence length is calculated for polyelectrolyte chains with fixed bond lengths and bond angles (pi-theta), and a potential energy consisting of the screened Coulomb interaction between beads, potential wells alpha phi(i)2 for the dihedral angles phi(i), and coupling terms beta phi(i) phi(i+/-1). This model defines a librating chain that reduces in appropriate limits to the freely rotating or wormlike chains, it can accommodate local crumpling or extreme stiffness, and it is easy to simulate. A planar-quadratic (pq), analytic approximation is based on an expansion of the electrostatic energy in eigenfunctions of the quadratic form that describes the backbone energy, and on the assumption that the quadratic form not only is positive but also adequately confines the chain in an infinite phase space of dihedral angles to the physically unique part with all |phi(i)| < pi. The pq approximation is available under these weak constraints, but the simulations confirm its quantitative accuracy only under the expected condition that alpha is large, that is, for very stiff chains. Stiff chains can also be simulated with small alpha and small theta and compared to an OSF approximation suitably generalized to chains with finite rather than vanishing theta, and increasing agreement with OSF is found the smaller is theta. The two approximations, one becoming exact as alpha --> infinity with fixed theta, the other as theta --> 0 with fixed alpha, are quantitatively similar in behavior, both giving a persistence length P = P0 + aD2 for stiff chains, where D is the Debye length. However, the coefficient apq is about twice the value of aOSF. Under other conditions the simulations show that P may or not be linear in D2 at small or moderate D, depending on the magnitudes of alpha, beta, theta, and the charge density but always becomes linear at large D. Even at a moderately low charge density, corresponding to fewer than 20% of the beads being charged, and with strong crumpling induced by large beta, increasing D dissolves blobs and recovers a linear dependence of P on D2, although a lower power of D gives an adequate fit at moderate D. For the class of models considered, it is concluded that the only universal feature is the asymptotic linearity of P in D2, regardless of flexibility or stiffness.

Nonmetallic electronegativity equalization and point-dipole interaction model including exchange interactions for molecular dipole moments and polarizabilities.

PubMed

Smalø, Hans S; Astrand, Per-Olof; Jensen, Lasse

2009-07-28

The electronegativity equalization model (EEM) has been combined with a point-dipole interaction model to obtain a molecular mechanics model consisting of atomic charges, atomic dipole moments, and two-atom relay tensors to describe molecular dipole moments and molecular dipole-dipole polarizabilities. The EEM has been phrased as an atom-atom charge-transfer model allowing for a modification of the charge-transfer terms to avoid that the polarizability approaches infinity for two particles at infinite distance and for long chains. In the present work, these shortcomings have been resolved by adding an energy term for transporting charges through individual atoms. A Gaussian distribution is adopted for the atomic charge distributions, resulting in a damping of the electrostatic interactions at short distances. Assuming that an interatomic exchange term may be described as the overlap between two electronic charge distributions, the EEM has also been extended by a short-range exchange term. The result is a molecular mechanics model where the difference of charge transfer in insulating and metallic systems is modeled regarding the difference in bond length between different types of system. For example, the model is capable of modeling charge transfer in both alkanes and alkenes with alternating double bonds with the same set of carbon parameters only relying on the difference in bond length between carbon sigma- and pi-bonds. Analytical results have been obtained for the polarizability of a long linear chain. These results show that the model is capable of describing the polarizability scaling both linearly and nonlinearly with the size of the system. Similarly, a linear chain with an end atom with a high electronegativity has been analyzed analytically. The dipole moment of this model system can either be independent of the length or increase linearly with the length of the chain. In addition, the model has been parametrized for alkane and alkene chains with data from density functional theory calculations, where the polarizability behaves differently with the chain length. For the molecular dipole moment, the same two systems have been studied with an aldehyde end group. Both the molecular polarizability and the dipole moment are well described as a function of the chain length for both alkane and alkene chains demonstrating the power of the presented model.

Kenneth Wilson and Lattice QCD

NASA Astrophysics Data System (ADS)

Ukawa, Akira

2015-09-01

We discuss the physics and computation of lattice QCD, a space-time lattice formulation of quantum chromodynamics, and Kenneth Wilson's seminal role in its development. We start with the fundamental issue of confinement of quarks in the theory of the strong interactions, and discuss how lattice QCD provides a framework for understanding this phenomenon. A conceptual issue with lattice QCD is a conflict of space-time lattice with chiral symmetry of quarks. We discuss how this problem is resolved. Since lattice QCD is a non-linear quantum dynamical system with infinite degrees of freedom, quantities which are analytically calculable are limited. On the other hand, it provides an ideal case of massively parallel numerical computations. We review the long and distinguished history of parallel-architecture supercomputers designed and built for lattice QCD. We discuss algorithmic developments, in particular the difficulties posed by the fermionic nature of quarks, and their resolution. The triad of efforts toward better understanding of physics, better algorithms, and more powerful supercomputers have produced major breakthroughs in our understanding of the strong interactions. We review the salient results of this effort in understanding the hadron spectrum, the Cabibbo-Kobayashi-Maskawa matrix elements and CP violation, and quark-gluon plasma at high temperatures. We conclude with a brief summary and a future perspective.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pratapa, Phanisri P.; Suryanarayana, Phanish; Pask, John E.

We present the Clenshaw–Curtis Spectral Quadrature (SQ) method for real-space O(N) Density Functional Theory (DFT) calculations. In this approach, all quantities of interest are expressed as bilinear forms or sums over bilinear forms, which are then approximated by spatially localized Clenshaw–Curtis quadrature rules. This technique is identically applicable to both insulating and metallic systems, and in conjunction with local reformulation of the electrostatics, enables the O(N) evaluation of the electronic density, energy, and atomic forces. The SQ approach also permits infinite-cell calculations without recourse to Brillouin zone integration or large supercells. We employ a finite difference representation in order tomore » exploit the locality of electronic interactions in real space, enable systematic convergence, and facilitate large-scale parallel implementation. In particular, we derive expressions for the electronic density, total energy, and atomic forces that can be evaluated in O(N) operations. We demonstrate the systematic convergence of energies and forces with respect to quadrature order as well as truncation radius to the exact diagonalization result. In addition, we show convergence with respect to mesh size to established O(N 3) planewave results. In conclusion, we establish the efficiency of the proposed approach for high temperature calculations and discuss its particular suitability for large-scale parallel computation.« less

Analytical model for vibration prediction of two parallel tunnels in a full-space

NASA Astrophysics Data System (ADS)

He, Chao; Zhou, Shunhua; Guo, Peijun; Di, Honggui; Zhang, Xiaohui

2018-06-01

This paper presents a three-dimensional analytical model for the prediction of ground vibrations from two parallel tunnels embedded in a full-space. The two tunnels are modelled as cylindrical shells of infinite length, and the surrounding soil is modelled as a full-space with two cylindrical cavities. A virtual interface is introduced to divide the soil into the right layer and the left layer. By transforming the cylindrical waves into the plane waves, the solution of wave propagation in the full-space with two cylindrical cavities is obtained. The transformations from the plane waves to cylindrical waves are then used to satisfy the boundary conditions on the tunnel-soil interfaces. The proposed model provides a highly efficient tool to predict the ground vibration induced by the underground railway, which accounts for the dynamic interaction between neighbouring tunnels. Analysis of the vibration fields produced over a range of frequencies and soil properties is conducted. When the distance between the two tunnels is smaller than three times the tunnel diameter, the interaction between neighbouring tunnels is highly significant, at times in the order of 20 dB. It is necessary to consider the interaction between neighbouring tunnels for the prediction of ground vibrations induced underground railways.

Spectral Quadrature method for accurate O ( N ) electronic structure calculations of metals and insulators

DOE PAGES

Pratapa, Phanisri P.; Suryanarayana, Phanish; Pask, John E.

2015-12-02

We present the Clenshaw–Curtis Spectral Quadrature (SQ) method for real-space O(N) Density Functional Theory (DFT) calculations. In this approach, all quantities of interest are expressed as bilinear forms or sums over bilinear forms, which are then approximated by spatially localized Clenshaw–Curtis quadrature rules. This technique is identically applicable to both insulating and metallic systems, and in conjunction with local reformulation of the electrostatics, enables the O(N) evaluation of the electronic density, energy, and atomic forces. The SQ approach also permits infinite-cell calculations without recourse to Brillouin zone integration or large supercells. We employ a finite difference representation in order tomore » exploit the locality of electronic interactions in real space, enable systematic convergence, and facilitate large-scale parallel implementation. In particular, we derive expressions for the electronic density, total energy, and atomic forces that can be evaluated in O(N) operations. We demonstrate the systematic convergence of energies and forces with respect to quadrature order as well as truncation radius to the exact diagonalization result. In addition, we show convergence with respect to mesh size to established O(N 3) planewave results. In conclusion, we establish the efficiency of the proposed approach for high temperature calculations and discuss its particular suitability for large-scale parallel computation.« less

Diffusive Imaging of Hydraulically Induced and Natural Fracture Systems

NASA Astrophysics Data System (ADS)

Eftekhari, B.; Marder, M. P.; Patzek, T. W.

2017-12-01

Hydraulic fracturing of tight shales continues to provide the US with a major source of energy. Efficiency of gas recovery in shales depends upon the geometry of the resulting network of fractures, the details of which are not yet fully understood. The present research explores how much of the underlying geometry can be deduced from the time dependence of the flow of gas out of the reservoir. We consider both ideal and real gas. In the case of real gas, we calculate production rate for parallel planar hydrofractures embedded in an infinite reservoir. Transport is governed by a nonlinear diffusion equation, which we solve exactly with a scaling curve. The scaling curve production rate declines initially as 1 over square root time, then as an exponential, and finally as 1 over square root of time again at late time. We show that for a given hydraulically fractured well, the onsets of transition between different decline regimes provides a direct estimate of a characteristic spacing of the underlying fracture network. We show that the scaling solution accurately fits the production history of more than 15,000 wells in the Barnett Shale. Almost all of the wells either have not yet transitioned into the late time decline or have been refractured while in exponential decline. However, there are 36 wells which show the late time transition. These allow us to calculate the characteristic spacing, which turns out to have a mode at about 10 m, a minimum at 1.6 m and a maximum at 13.3 m. We estimate that over 30 years these wells will produce on average about 45% more gas because of diffusion from the infinite external reservoir than they would if this contribution is neglected. Finally, we compute the rate at which ideal gas diffuses within an infinite region of rock into a specific absorbing fractal fracture network, which we model using geological constraints and percolation theory. Our solution employs a Brownian walk and the first passage kinetic Monte Carlo algorithm that is robust and efficient. A striking feature of this solution is the presence of a power law decline.

Time-dependent density functional theory with twist-averaged boundary conditions

NASA Astrophysics Data System (ADS)

Schuetrumpf, B.; Nazarewicz, W.; Reinhard, P.-G.

2016-05-01

Background: Time-dependent density functional theory is widely used to describe excitations of many-fermion systems. In its many applications, three-dimensional (3D) coordinate-space representation is used, and infinite-domain calculations are limited to a finite volume represented by a spatial box. For finite quantum systems (atoms, molecules, nuclei, hadrons), the commonly used periodic or reflecting boundary conditions introduce spurious quantization of the continuum states and artificial reflections from boundary; hence, an incorrect treatment of evaporated particles. Purpose: The finite-volume artifacts for finite systems can be practically cured by invoking an absorbing potential in a certain boundary region sufficiently far from the described system. However, such absorption cannot be applied in the calculations of infinite matter (crystal electrons, quantum fluids, neutron star crust), which suffer from unphysical effects stemming from a finite computational box used. Here, twist-averaged boundary conditions (TABC) have been used successfully to diminish the finite-volume effects. In this work, we extend TABC to time-dependent modes. Method: We use the 3D time-dependent density functional framework with the Skyrme energy density functional. The practical calculations are carried out for small- and large-amplitude electric dipole and quadrupole oscillations of 16O. We apply and compare three kinds of boundary conditions: periodic, absorbing, and twist-averaged. Results: Calculations employing absorbing boundary conditions (ABC) and TABC are superior to those based on periodic boundary conditions. For low-energy excitations, TABC and ABC variants yield very similar results. With only four twist phases per spatial direction in TABC, one obtains an excellent reduction of spurious fluctuations. In the nonlinear regime, one has to deal with evaporated particles. In TABC, the floating nucleon gas remains in the box; the amount of nucleons in the gas is found to be roughly the same as the number of absorbed particles in ABC. Conclusion: We demonstrate that by using TABC, one can reduce finite-volume effects drastically without adding any additional parameters associated with absorption at large distances. Moreover, TABC are an obvious choice for time-dependent calculations for infinite systems. Since TABC calculations for different twists can be performed independently, the method is trivially adapted to parallel computing.

Effect of experimental diabetes on the levels of aromatic and branched-chain amino acids in rat blood and brain.

PubMed

Crandall, E A; Fernstrom, J D

1983-03-01

Male rats treated 3 wk earlier with streptozotocin showed abnormally high blood levels of leucine, isoleucine, and valine throughout the 24-h period. Serum phenylalanine levels were slightly increased, while those of tryptophan and tyrosine were occasionally reduced. In brain, the level of each branched-chain amino acid was significantly increased above normal at all times. The brain concentration of each aromatic amino acid was always below normal. These changes were restored almost to normal by exogenous insulin therapy. Since the ingestion of protein is normally a major factor influencing blood amino acid levels, the effect of ingesting single, protein-containing meals on the blood and brain levels of these amino acids was also studied. After an overnight fast, the ingestion of a protein-containing meal by diabetic rats increased substantially both blood and brain levels of each branched-chain amino acid. No such increases occurred in normal rats. Ingestion of this meal produced only small changes in the brain and blood levels of the aromatic amino acids in both diabetic and normal rats. The changes in the brain level of each large neutral amino acid in some cases paralleled those in its blood level. More often, they paralleled the changes in the blood ratio of each amino acid to the sum of the other aromatic and branched-chain amino acids. This ratio is often a good predictor of the competitive transport of these amino acids into brain (Fernstrom and Faller, 1978). The observed changes in the brain levels of these amino acids in diabetes may influence the rates at which they are consumed in metabolic pathways within this organ.

Cyanide-bridged Fe(III)-Mn(III) bimetallic complexes with dimeric and chain structures constructed from a newly made mer-Fe tricyanide: structures and magnetic properties.

PubMed

Kim, Jae Il; Kwak, Hyun Young; Yoon, Jung Hee; Ryu, Dae Won; Yoo, In Young; Yang, Namgeun; Cho, Beong Ki; Park, Je-Geun; Lee, Hyosug; Hong, Chang Seop

2009-04-06

Four cyanide-linked Fe(III)-Mn(III) complexes were prepared by reacting Mn Schiff bases with a new molecular precursor (PPh(4))[Fe(qcq)(CN)(3)] [1; qcq = 8-(2-quinolinecarboxamido)quinoline anion]. They include a dimeric molecule, [Fe(qcq)(CN)(3)][Mn(3-MeOsalen)(H(2)O)] x 2 H(2)O [2 x 2 H(2)O; 3-MeOsalen = N,N'-ethylenebis(3-methoxysalicylideneiminato) dianion], and three 1D zigzag chains, [Fe(qcq)(CN)(3)][Mn(5-Clsalen)] x 3 H(2)O [3 x 2 MeOH; 5-Clsalen = N,N'-ethylenebis(5-chlorosalicylideneiminato) dianion], [Fe(qcq)(CN)(3)][Mn(5-Brsalen)] x 2 MeOH [4 x 2 MeOH; 5-Brsalen = N,N'-ethylenebis(5-bromosalicylideneiminato) dianion], and Fe(qcq)(CN)(3)][Mn(salen)].MeCN x H(2)O [5 x MeCN; salen = N,N'-ethylenebis(salicylideneiminato) dianion]. The complexes consist of extensive hydrogen bonding and pi-pi stacking interactions, generating multidimensional structures. Magnetic studies demonstrate that antiferromagnetic couplings are operative between Fe(III) and Mn(III) centers bridged by cyanide ligands. On the basis of an infinite chain model, magnetic coupling parameters of 2-5 range from -9.3 to -14.1 cm(-1). A long-range order is observed at 2.3 K for 3 and 2.2 K for 4, while compound 5 shows spin glass behavior possibly coupled with magnetic ordering.

Thermodynamics of a dilute XX chain in a field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timonin, P. N., E-mail: pntim@live.ru

Gapless phases in ground states of low-dimensional quantum spin systems are rather ubiquitous. Their peculiarity is a remarkable sensitivity to external perturbations due to permanent criticality of such phases manifested by a slow (power-low) decay of pair correlations and the divergence of the corresponding susceptibility. A strong influence of various defects on the properties of the system in such a phase can then be expected. Here, we consider the influence of vacancies on the thermodynamics of the simplest quantum model with a gapless phase, the isotropic spin-1/2 XX chain. The existence of the exact solution of this model gives amore » unique opportunity to describe in detail the dramatic effect of dilution on the gapless phase—the appearance of an infinite series of quantum phase transitions resulting from level crossing under the variation of a longitudinal magnetic field. We calculate the jumps in the field dependences of the ground-state longitudinal magnetization, susceptibility, entropy, and specific heat appearing at these transitions and show that they result in a highly nonlinear temperature dependence of these parameters at low T. Also, the effect of enhancement of the magnetization and longitudinal correlations in the dilute chain is established. The changes of the pair spin correlators under dilution are also analyzed. The universality of the mechanism of the quantum transition generation suggests that similar effects of dilution can also be expected in gapless phases of other low-dimensional quantum spin systems.« less

Solvothermal syntheses and characterization of three new silver(I)/copper(I)-thioarsenates based on As{sup 2+}/As{sup 3+} ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Hua-Gang, E-mail: hgyao@gdpu.edu.cn; Guangdong Cosmetics Engineering & Technology Research Center, Zhongshan 528458; Tang, Cheng-Fei

2017-02-15

Three new silver(I)/copper(I)-thioarsenates KAgAs{sup II}S{sub 2} (1), RbCu{sub 2}As{sup III}S{sub 3} (2) and RbCu{sub 4}As{sup III}S{sub 4} (3) have been solvothermally synthesized and structurally characterized. 1 exhibits a two-dimensional anionic network built up by As−As bond connecting the left- and right-handed helical [AgS{sub 2}]{sup 4−} chains, and represents the first examples of thioarsenates(II). The structure of 2 consists of two kinds of helical [Cu{sub 2}S{sub 3}]{sup 4–} chains linked by the arsenic atoms to form double layers with rubidium ions between the layers. Compound 3 is built up of infinite [Cu{sub 2}S{sub 2}]{sup 2–} chain and layered [Cu{sub 6}As{sub 2}S{submore » 6}] linked to form a three-dimensional anionic framework, [Cu{sub 4}AsS{sub 4}]{sup –}, and containing channels in which the rubidium cations reside. The optical properties of 1–3 have been investigated by UV–vis spectroscopy. - Graphical abstract: Three new silver(I)/copper(I)-thioarsenates have been solvothermally synthesized and structurally characterized. 1 represents the first examples of thioarsenates(II) while compounds 2 and 3 possess noncondensed pyramidal AsS{sub 3}{sup 3–} unit.« less

Large-amplitude nonlinear normal modes of the discrete sine lattices.

PubMed

Smirnov, Valeri V; Manevitch, Leonid I

2017-02-01

We present an analytical description of the large-amplitude stationary oscillations of the finite discrete system of harmonically coupled pendulums without any restrictions on their amplitudes (excluding a vicinity of π). Although this model has numerous applications in different fields of physics, it was studied earlier in the infinite limit only. The discrete chain with a finite length can be considered as a well analytical analog of the coarse-grain models of flexible polymers in the molecular dynamics simulations. The developed approach allows to find the dispersion relations for arbitrary amplitudes of the nonlinear normal modes. We emphasize that the long-wavelength approximation, which is described by well-known sine-Gordon equation, leads to an inadequate zone structure for the amplitudes of about π/2 even if the chain is long enough. An extremely complex zone structure at the large amplitudes corresponds to multiple resonances between nonlinear normal modes even with strongly different wave numbers. Due to the complexity of the dispersion relations the modes with shorter wavelengths may have smaller frequencies. The stability of the nonlinear normal modes under condition of the resonant interaction are discussed. It is shown that this interaction of the modes in the vicinity of the long wavelength edge of the spectrum leads to the localization of the oscillations. The thresholds of instability and localization are determined explicitly. The numerical simulation of the dynamics of a finite-length chain is in a good agreement with obtained analytical predictions.

A series of Cadmium(II) complexes with 2-substituted terephthalate building block and N-Donor co-ligands: Structural diversity and fluorescence properties

NASA Astrophysics Data System (ADS)

Ren, Yixia; Zhou, Shanhong; Wang, Zhixiang; Zhang, Meili; Wang, Jijiang; Cao, Jia

2017-11-01

Four new Cd(II) complexes have been prepared based on 1,2,4-trimellitic acid (H3tma) and monosodium 2-sulfoterephthalate (2-NaH2stp), formulated as [Cd2(Htma)2 (dpp)2(H2O)] (1), [Cd3 (tma)2 (2,4-bipy)4(H2O)2] (2), [Cd (2-Hstp) (2,2'-bipy)2]·2H2O (3) and [Cd (2-Hstp) (2,4-bipy) (H2O)2] (4) (dpp = dipyrido [3,2-a:2‧,3'-c] phenazine, 2,4-bipy = 2,4-bipyridine, 2,2'-bipy = 2,2'- bipyridine) by hydrothermal method. X-ray diffraction structural analyses show all these complexes crystallized in triclinic crystal system of Pī space group, but their structures are diverse. Complex 1 exhibits an infinite one-dimensional chain featuring the left- and right-handed stranded chains interweaved each other. For 2, the two-dimensional network is constructed by one-dimensional ladder-like chain linked by Cd2 ions. In complex 3, the cadmium ion is surrounded with one 2-Hstp2- anion and two 2,2'-bipy molecules. Complex 4 is also a discrete structure based on a metallic dimer unit. In all these complexes, the N-donor co-ligands take the important roles in the assembly of three-dimensional supramolecular structures. The fluorescence properties of complexes 1-4 could be assigned to the π - π* transition of organic ligands.

Stochastic dynamics of time correlation in complex systems with discrete time

NASA Astrophysics Data System (ADS)

Yulmetyev, Renat; Hänggi, Peter; Gafarov, Fail

2000-11-01

In this paper we present the concept of description of random processes in complex systems with discrete time. It involves the description of kinetics of discrete processes by means of the chain of finite-difference non-Markov equations for time correlation functions (TCFs). We have introduced the dynamic (time dependent) information Shannon entropy Si(t) where i=0,1,2,3,..., as an information measure of stochastic dynamics of time correlation (i=0) and time memory (i=1,2,3,...). The set of functions Si(t) constitute the quantitative measure of time correlation disorder (i=0) and time memory disorder (i=1,2,3,...) in complex system. The theory developed started from the careful analysis of time correlation involving dynamics of vectors set of various chaotic states. We examine two stochastic processes involving the creation and annihilation of time correlation (or time memory) in details. We carry out the analysis of vectors' dynamics employing finite-difference equations for random variables and the evolution operator describing their natural motion. The existence of TCF results in the construction of the set of projection operators by the usage of scalar product operation. Harnessing the infinite set of orthogonal dynamic random variables on a basis of Gram-Shmidt orthogonalization procedure tends to creation of infinite chain of finite-difference non-Markov kinetic equations for discrete TCFs and memory functions (MFs). The solution of the equations above thereof brings to the recurrence relations between the TCF and MF of senior and junior orders. This offers new opportunities for detecting the frequency spectra of power of entropy function Si(t) for time correlation (i=0) and time memory (i=1,2,3,...). The results obtained offer considerable scope for attack on stochastic dynamics of discrete random processes in a complex systems. Application of this technique on the analysis of stochastic dynamics of RR intervals from human ECG's shows convincing evidence for a non-Markovian phenomemena associated with a peculiarities in short- and long-range scaling. This method may be of use in distinguishing healthy from pathologic data sets based in differences in these non-Markovian properties.