Multicritical phase diagrams of the Blume-Emery-Griffiths model with repulsive biquadratic coupling including metastable phases: the pair approximation and the path probability method with pair distribution

International Nuclear Information System (INIS)

Keskin, Mustafa; Erdinc, Ahmet

2004-01-01

As a continuation of the previously published work, the pair approximation of the cluster variation method is applied to study the temperature dependences of the order parameters of the Blume-Emery-Griffiths model with repulsive biquadratic coupling on a body centered cubic lattice. We obtain metastable and unstable branches of the order parameters besides the stable branches and phase transitions of these branches are investigated extensively. We study the dynamics of the model by the path probability method with pair distribution in order to make sure that we find and define the metastable and unstable branches of the order parameters completely and correctly. We present the metastable phase diagram in addition to the equilibrium phase diagram and also the first-order phase transition line for the unstable branches of the quadrupole order parameter is superimposed on the phase diagrams. It is found that the metastable phase diagram and the first-order phase boundary for the unstable quadrupole order parameter always exist at the low temperatures which are consistent with experimental and theoretical works

Symmetry of order-parameters in high-Tc layered superconductors

International Nuclear Information System (INIS)

Rajagopal, A.K.; Jha, Sudhanshu S.

1997-01-01

It is well known that the anisotropy and wave-vector dependence of the energy-gap function determine many important properties of a superconductor which are relevant for device applications. Apart from a weak dependence on the wave-vector k - > in the direction perpendicular to the reciprocal layer-plane of a high-T c layered superconductor, it is shown that anisotropic superconducting order parameters for intra-layer pairing in the class of such materials with orthorhombic crystal structures, can have either pure s-wave like symmetry or mixed d-wave and anisotropic extended s-wave like symmetries in the reciprocal layer-plane. However, in such materials with tetragonal crystal structures, it is possible to have a pure s-wave like symmetry, which may be either isotropic or anisotropic in the layer k - >-space, or a pure d-wave like symmetry, as far the k - >-dependence in the reciprocal layer plane is concerned. In view of this, some suggestions for analysing experimental data will also be presented. (author)

Entanglement-assisted quantum parameter estimation from a noisy qubit pair: A Fisher information analysis

Energy Technology Data Exchange (ETDEWEB)

Chapeau-Blondeau, François, E-mail: chapeau@univ-angers.fr

2017-04-25

Benefit from entanglement in quantum parameter estimation in the presence of noise or decoherence is investigated, with the quantum Fisher information to asses the performance. When an input probe experiences any (noisy) transformation introducing the parameter dependence, the performance is always maximized by a pure probe. As a generic estimation task, for estimating the phase of a unitary transformation on a qubit affected by depolarizing noise, the optimal separable probe and its performance are characterized as a function of the level of noise. By entangling qubits in pairs, enhancements of performance over that of the optimal separable probe are quantified, in various settings of the entangled pair. In particular, in the presence of the noise, enhancement over the performance of the one-qubit optimal probe can always be obtained with a second entangled qubit although never interacting with the process to be estimated. Also, enhancement over the performance of the two-qubit optimal separable probe can always be achieved by a two-qubit entangled probe, either partially or maximally entangled depending on the level of the depolarizing noise. - Highlights: • Quantum parameter estimation from a noisy qubit pair is investigated. • The quantum Fisher information is used to assess the ultimate best performance. • Theoretical expressions are established and analyzed for the Fisher information. • Enhanced performances are quantified with various entanglements of the pair. • Enhancement is shown even with one entangled qubit noninteracting with the process.

Possibilities of paired comparison of receptor binding parameters obtained in a single experiment

International Nuclear Information System (INIS)

Mashilova, K.V.; Kiriakov, G.V.; Malin, K.M.; Rozhanets, V.V.

1987-01-01

The authors explore the use of comparing control and experimental groups on the basis of extrapolation parameters obtained from a single pair of experiments. One of the experiments study the parameters of specific binding of 3 H-D-ala-2-enkephelin-5-D-leucine in the striatum of different groups of rats. The analysis was done by the Cornish-Bowden method

Examining a Thermodynamic Order Parameter of Protein Folding.

Science.gov (United States)

Chong, Song-Ho; Ham, Sihyun

2018-05-08

Dimensionality reduction with a suitable choice of order parameters or reaction coordinates is commonly used for analyzing high-dimensional time-series data generated by atomistic biomolecular simulations. So far, geometric order parameters, such as the root mean square deviation, fraction of native amino acid contacts, and collective coordinates that best characterize rare or large conformational transitions, have been prevailing in protein folding studies. Here, we show that the solvent-averaged effective energy, which is a thermodynamic quantity but unambiguously defined for individual protein conformations, serves as a good order parameter of protein folding. This is illustrated through the application to the folding-unfolding simulation trajectory of villin headpiece subdomain. We rationalize the suitability of the effective energy as an order parameter by the funneledness of the underlying protein free energy landscape. We also demonstrate that an improved conformational space discretization is achieved by incorporating the effective energy. The most distinctive feature of this thermodynamic order parameter is that it works in pointing to near-native folded structures even when the knowledge of the native structure is lacking, and the use of the effective energy will also find applications in combination with methods of protein structure prediction.

Testing for one Generalized Linear Single Order Parameter

DEFF Research Database (Denmark)

Ellegaard, Niels Langager; Christensen, Tage Emil; Dyre, Jeppe

We examine a linear single order parameter model for thermoviscoelastic relaxation in viscous liquids, allowing for a distribution of relaxation times. In this model the relaxation of volume and entalpy is completely described by the relaxation of one internal order parameter. In contrast to prior...... work the order parameter may be chosen to have a non-exponential relaxation. The model predictions contradict the general consensus of the properties of viscous liquids in two ways: (i) The model predicts that following a linear isobaric temperature step, the normalized volume and entalpy relaxation...... responses or extrapolate from measurements of a glassy state away from equilibrium. Starting from a master equation description of inherent dynamics, we calculate the complex thermodynamic response functions. We device a way of testing for the generalized single order parameter model by measuring 3 complex...

Quantum fluctuation of the order parameter in polyacetylene

International Nuclear Information System (INIS)

Su Zhao-bin; Wang Ya-xin; Yu Lu.

1984-07-01

The effects of the lattice quantum fluctuation upon the order parameter in the Peierls systems are studied by using the Green's function technique. The order parameter is reduced but survives the quantum fluctuations in agreement with the Monte Carlo simulations. (author)

Pairing fluctuations in trapped Fermi gases

International Nuclear Information System (INIS)

Viverit, Luciano; Bruun, Georg M.; Minguzzi, Anna; Fazio, Rosario

2004-01-01

We examine the contribution of pairing fluctuations to the superfluid order parameter for harmonically trapped atomic Fermi gases in the BCS regime. In the limit of small systems we consider, both analytically and numerically, their space and temperature dependence. We predict a parity effect, i.e., that pairing fluctuations show a maximum or a minimum at the center of the trap, depending on the value of the last occupied shell being even or odd. We propose to detect pairing fluctuations by measuring the density-density correlation function after a ballistic expansion of the gas

Pairing of parafermions of order 2: seniority model

International Nuclear Information System (INIS)

Nelson, Charles A

2004-01-01

As generalizations of the fermion seniority model, four multi-mode Hamiltonians are considered to investigate some of the consequences of the pairing of parafermions of order 2. Two- and four-particle states are explicitly constructed for H A ≡ -GA†A with A† ≡ 1/2 Σ m>0 c† m c† -m and the distinct H C ≡ -GC†C with C† ≡ 1/2 Σ m>0 c† -m c† m , and for the time-reversal invariant H (-) ≡ -G(A† - C†)(A - C) and H (+) ≡ -G(A† + C†)(A + C), which has no analogue in the fermion case. The spectra and degeneracies are compared with those of the usual fermion seniority model

Determination of the pairing-strength constants in the isovector plus isoscalar pairing case

Science.gov (United States)

Mokhtari, D.; Fellah, M.; Allal, N. H.

2016-05-01

A method for the determination of the pairing-strength constants, in the neutron-proton (n-p) isovector plus isoscalar pairing case, is proposed in the framework of the BCS theory. It is based on the fitting of these constants to reproduce the experimentally known pairing gap parameters as well as the root-mean-squared (r.m.s) charge radii values. The method is applied to some proton-rich even-even nuclei. The single-particle energies used are those of a deformed Woods-Saxon mean field. It is shown that the obtained value of the ratio GnpT=0/G npT=1 is of the same order as the ones, arbitrary chosen, of some previous works. The effect of the inclusion of the isoscalar n-p pairing in the r.m.s matter radii is then numerically studied for the same nuclei.

Order parameters in smectic liquid crystals[Smectics

Energy Technology Data Exchange (ETDEWEB)

Beldon, Stephen M

2001-07-01

This thesis explores some of the important mechanisms for switching in smectic liquid crystals. It is mainly concerned with the interaction of the electric field and various order parameters in smectic phases. Distortion of these order parameters and also the layer structures associated with smectics are discussed in depth. Initial work is concentrated on the electroclinic effect of commercially available FLC mixtures, where experimental results suggest the presence of non-uniformity in the molecular director profile. Two possible models are suggested assuming a variation of the order parameter {theta} through the cell. The first model assumes that the smectic layers remain bookshelf-like, and the second that the layers tilt in a vertical chevron structure when a cone angle is induced electroclinically or otherwise. The latter model is the first 'order parameter' model of an electric field induced vertical chevron. The presence of non-uniformity in the director profile is sensed by a method similar to wavelength extinction spectroscopy. Investigations are undertaken on racemic smectic materials with high dielectric biaxiality. Modelling of such a material reveals a new electroclinic effect which shows a discrete second order phase transition on application of a field. It is suggested that a bistable electroclinic effect stabilised with a high frequency ac field may be realised if a residual polarisation is present in the high biaxiality material, and that this might be useful in the displays industry. Experimental investigations of such a material confirm the above effects close to the smectic A-C transition. Finally a higher order smectic phase, the smectic I* phase, is considered. The distortion of the hexagonal bond orientational order is investigated experimentally during application of an electric field. The first dynamic model of the switching process is presented, showing good agreement with the experimental results. It is suggested that the bond

BAYESIAN ANALYSIS FOR THE PAIRED COMPARISON MODEL WITH ORDER EFFECTS (USING NON-INFORMATIVE PRIORS

Directory of Open Access Journals (Sweden)

Ghausia Masood Gilani

2008-07-01

Full Text Available Sometimes it may be difficult for a panelist to rank or compare more than two objects or treatments at the same time. For this reason, paired comparison method is used. In this study, the Davidson and Beaver (1977 model for paired comparisons with order effects is analyzed through the Bayesian Approach. For this purpose, the posterior means and the posterior modes are compared using the noninformative priors.

Order parameter analysis of synchronization transitions on star networks

Science.gov (United States)

Chen, Hong-Bin; Sun, Yu-Ting; Gao, Jian; Xu, Can; Zheng, Zhi-Gang

2017-12-01

The collective behaviors of populations of coupled oscillators have attracted significant attention in recent years. In this paper, an order parameter approach is proposed to study the low-dimensional dynamical mechanism of collective synchronizations, by adopting the star-topology of coupled oscillators as a prototype system. The order parameter equation of star-linked phase oscillators can be obtained in terms of the Watanabe-Strogatz transformation, Ott-Antonsen ansatz, and the ensemble order parameter approach. Different solutions of the order parameter equation correspond to the diverse collective states, and different bifurcations reveal various transitions among these collective states. The properties of various transitions in the star-network model are revealed by using tools of nonlinear dynamics such as time reversibility analysis and linear stability analysis.

Amperean Pairing and the Pseudogap Phase of Cuprate Superconductors

Science.gov (United States)

Lee, Patrick A.

2014-07-01

The enigmatic pseudogap phase in underdoped cuprate high-Tc superconductors has long been recognized as a central puzzle of the Tc problem. Recent data show that the pseudogap is likely a distinct phase, characterized by a medium range and quasistatic charge ordering. However, the origin of the ordering wave vector and the mechanism of the charge order is unknown. At the same time, earlier data show that precursive superconducting fluctuations are also associated with this phase. We propose that the pseudogap phase is a novel pairing state where electrons on the same side of the Fermi surface are paired, in strong contrast with conventional Bardeen-Cooper-Schrieffer theory which pairs electrons on opposite sides of the Fermi surface. In this state the Cooper pair carries a net momentum and belongs to a general class called pair density wave. The microscopic pairing mechanism comes from a gauge theory formulation of the resonating valence bond (RVB) picture, where spinons traveling in the same direction feel an attractive force in analogy with Ampere's effects in electromagnetism. We call this Amperean pairing. Charge order automatically appears as a subsidiary order parameter even when long-range pair order is destroyed by phase fluctuations. Our theory gives a prediction of the ordering wave vector which is in good agreement with experiment. Furthermore, the quasiparticle spectrum from our model explains many of the unusual features reported in photoemission experiments. The Fermi arc, the unusual way the tip of the arc terminates, and the relation of the spanning vector of the arc tips to the charge ordering wave vector also come out naturally. Finally, we propose an experiment that can directly test the notion of Amperean pairing.

A continuum order parameter for deconfinement

International Nuclear Information System (INIS)

Roberts, C.D.

1997-01-01

Dyson-Schwinger equations are presented as a non-perturbative tool for the study and modeling of QCD at finite-T. An order parameter for deconfinement, applicable for both light and heavy quarks, is introduced. In a simple Dyson-Schwinger equation model of two-flavor QCD, coincident, 2nd-order chiral symmetry restoration and deconfinement transitions occur at T ∼ 150 MeV, with the same critical exponent, Β ∼ 0.33

Local and nonlocal order parameters in the Kitaev chain

Science.gov (United States)

Chitov, Gennady Y.

2018-02-01

We have calculated order parameters for the phases of the Kitaev chain with interaction and dimerization at a special symmetric point applying the Jordan-Wigner and other duality transformations. We use string order parameters (SOPs) defined via the correlation functions of the Majorana string operators. The SOPs are mapped onto the local order parameters of some dual Hamiltonians and easily calculated. We have shown that the phase diagram of the interacting dimerized chain comprises the phases with the conventional local order as well as the phases with nonlocal SOPs. From the results for the critical indices, we infer the two-dimensional Ising universality class of criticality at the particular symmetry point where the model is exactly solvable.

Time- and Space-Order Effects in Timed Discrimination of Brightness and Size of Paired Visual Stimuli

Science.gov (United States)

Patching, Geoffrey R.; Englund, Mats P.; Hellstrom, Ake

2012-01-01

Despite the importance of both response probability and response time for testing models of choice, there is a dearth of chronometric studies examining systematic asymmetries that occur over time- and space-orders in the method of paired comparisons. In this study, systematic asymmetries in discriminating the magnitude of paired visual stimuli are…

Orbitally limited pair-density-wave phase of multilayer superconductors

Science.gov (United States)

Möckli, David; Yanase, Youichi; Sigrist, Manfred

2018-04-01

We investigate the magnetic field dependence of an ideal superconducting vortex lattice in the parity-mixed pair-density-wave phase of multilayer superconductors within a circular cell Ginzburg-Landau approach. In multilayer systems, due to local inversion symmetry breaking, a Rashba spin-orbit coupling is induced at the outer layers. This combined with a perpendicular paramagnetic (Pauli) limiting magnetic field stabilizes a staggered layer dependent pair-density-wave phase in the superconducting singlet channel. The high-field pair-density-wave phase is separated from the low-field BCS phase by a first-order phase transition. The motivating guiding question in this paper is: What is the minimal necessary Maki parameter αM for the appearance of the pair-density-wave phase of a superconducting trilayer system? To address this problem we generalize the circular cell method for the regular flux-line lattice of a type-II superconductor to include paramagnetic depairing effects. Then, we apply the model to the trilayer system, where each of the layers are characterized by Ginzburg-Landau parameter κ0 and a Maki parameter αM. We find that when the spin-orbit Rashba interaction compares to the superconducting condensation energy, the orbitally limited pair-density-wave phase stabilizes for Maki parameters αM>10 .

Order parameters for symmetry-breaking structural transitions: The tetragonal-monoclinic transition in ZrO2

Science.gov (United States)

Thomas, John C.; Van der Ven, Anton

2017-10-01

Group/subgroup structural phase transitions are exploited in a wide variety of technologies, including those that rely on shape-memory behavior and on transformation toughening. Here, we introduce an approach to identify symmetry-adapted strain and shuffle order parameters for any group/subgroup structural transition between a high-symmetry parent phase and its symmetrically equivalent low-symmetry product phases. We show that symmetry-adapted atomic shuffle order parameters can be determined by the diagonalization of an orbital covariance matrix, formed by taking the covariance among the atomic displacement vectors of all symmetrically equivalent product phase variants. We use this approach to analyze the technologically important tetragonal to monoclinic structural phase transformation of ZrO2. We explore the energy landscapes, as calculated with density functional theory, along distinct paths that connect m ZrO2 to t ZrO2 and to other m ZrO2 variants. The calculations indicate favorable pairs of variants and reveal intermediate structures likely to exist at coherent twin boundaries and having relatively low deformation energy. We identify crystallographic features of the monoclinic ZrO2 variant that make it very sensitive to shape changing strains.

Dynamical vanishing of the order parameter in a confined Bardeen-Cooper-Schrieffer Fermi gas after an interaction quench

Science.gov (United States)

Hannibal, S.; Kettmann, P.; Croitoru, M. D.; Axt, V. M.; Kuhn, T.

2018-01-01

We present a numerical study of the Higgs mode in an ultracold confined Fermi gas after an interaction quench and find a dynamical vanishing of the superfluid order parameter. Our calculations are done within a microscopic density-matrix approach in the Bogoliubov-de Gennes framework which takes the three-dimensional cigar-shaped confinement explicitly into account. In this framework, we study the amplitude mode of the order parameter after interaction quenches starting on the BCS side of the BEC-BCS crossover close to the transition and ending in the BCS regime. We demonstrate the emergence of a dynamically vanishing superfluid order parameter in the spatiotemporal dynamics in a three-dimensional trap. Further, we show that the signal averaged over the whole trap mirrors the spatiotemporal behavior and allows us to systematically study the effects of the system size and aspect ratio on the observed dynamics. Our analysis enables us to connect the confinement-induced modifications of the dynamics to the pairing properties of the system. Finally, we demonstrate that the signature of the Higgs mode is contained in the dynamical signal of the condensate fraction, which, therefore, might provide a new experimental access to the nonadiabatic regime of the Higgs mode.

Junctionless Cooper pair transistor

Energy Technology Data Exchange (ETDEWEB)

Arutyunov, K. Yu., E-mail: konstantin.yu.arutyunov@jyu.fi [National Research University Higher School of Economics , Moscow Institute of Electronics and Mathematics, 101000 Moscow (Russian Federation); P.L. Kapitza Institute for Physical Problems RAS , Moscow 119334 (Russian Federation); Lehtinen, J.S. [VTT Technical Research Centre of Finland Ltd., Centre for Metrology MIKES, P.O. Box 1000, FI-02044 VTT (Finland)

2017-02-15

Highlights: • Junctionless Cooper pair box. • Quantum phase slips. • Coulomb blockade and gate modulation of the Coulomb gap. - Abstract: Quantum phase slip (QPS) is the topological singularity of the complex order parameter of a quasi-one-dimensional superconductor: momentary zeroing of the modulus and simultaneous 'slip' of the phase by ±2π. The QPS event(s) are the dynamic equivalent of tunneling through a conventional Josephson junction containing static in space and time weak link(s). Here we demonstrate the operation of a superconducting single electron transistor (Cooper pair transistor) without any tunnel junctions. Instead a pair of thin superconducting titanium wires in QPS regime was used. The current–voltage characteristics demonstrate the clear Coulomb blockade with magnitude of the Coulomb gap modulated by the gate potential. The Coulomb blockade disappears above the critical temperature, and at low temperatures can be suppressed by strong magnetic field.

Single-order-parameter description of glass-forming liquids

DEFF Research Database (Denmark)

Ellegaard, Niels Langager; Christensen, Tage Emil; Christiansen, Peder Voetmann

2007-01-01

Thermoviscoelastic linear-response functions are calculated from the master equation describing viscous liquid inherent dynamics. From the imaginary parts of the frequency-dependent isobaric specific heat, isothermal compressibility, and isobaric thermal expansion coefficient, we define a "linear...... dynamic Prigogine-Defay ratio" with the property that if this ratio is unity at one frequency, then it is unity at all frequencies. This happens if and only if there is a single-order-parameter description of the thermoviscoelastic linear responses via an order parameter which may be nonexponential...

The role of visual representations within working memory for paired-associate and serial order of spoken words.

Science.gov (United States)

Ueno, Taiji; Saito, Satoru

2013-09-01

Caplan and colleagues have recently explained paired-associate learning and serial-order learning with a single-mechanism computational model by assuming differential degrees of isolation. Specifically, two items in a pair can be grouped together and associated to positional codes that are somewhat isolated from the rest of the items. In contrast, the degree of isolation among the studied items is lower in serial-order learning. One of the key predictions drawn from this theory is that any variables that help chunking of two adjacent items into a group should be beneficial to paired-associate learning, more than serial-order learning. To test this idea, the role of visual representations in memory for spoken verbal materials (i.e., imagery) was compared between two types of learning directly. Experiment 1 showed stronger effects of word concreteness and of concurrent presentation of irrelevant visual stimuli (dynamic visual noise: DVN) in paired-associate memory than in serial-order memory, consistent with the prediction. Experiment 2 revealed that the irrelevant visual stimuli effect was boosted when the participants had to actively maintain the information within working memory, rather than feed it to long-term memory for subsequent recall, due to cue overloading. This indicates that the sensory input from irrelevant visual stimuli can reach and affect visual representations of verbal items within working memory, and that this disruption can be attenuated when the information within working memory can be efficiently supported by long-term memory for subsequent recall.

Pair plasma relaxation time scales.

Science.gov (United States)

Aksenov, A G; Ruffini, R; Vereshchagin, G V

2010-04-01

By numerically solving the relativistic Boltzmann equations, we compute the time scale for relaxation to thermal equilibrium for an optically thick electron-positron plasma with baryon loading. We focus on the time scales of electromagnetic interactions. The collisional integrals are obtained directly from the corresponding QED matrix elements. Thermalization time scales are computed for a wide range of values of both the total-energy density (over 10 orders of magnitude) and of the baryonic loading parameter (over 6 orders of magnitude). This also allows us to study such interesting limiting cases as the almost purely electron-positron plasma or electron-proton plasma as well as intermediate cases. These results appear to be important both for laboratory experiments aimed at generating optically thick pair plasmas as well as for astrophysical models in which electron-positron pair plasmas play a relevant role.

Analytic energy derivatives for the calculation of the first-order molecular properties using the domain-based local pair-natural orbital coupled-cluster theory

Science.gov (United States)

Datta, Dipayan; Kossmann, Simone; Neese, Frank

2016-09-01

The domain-based local pair-natural orbital coupled-cluster (DLPNO-CC) theory has recently emerged as an efficient and powerful quantum-chemical method for the calculation of energies of molecules comprised of several hundred atoms. It has been demonstrated that the DLPNO-CC approach attains the accuracy of a standard canonical coupled-cluster calculation to about 99.9% of the basis set correlation energy while realizing linear scaling of the computational cost with respect to system size. This is achieved by combining (a) localized occupied orbitals, (b) large virtual orbital correlation domains spanned by the projected atomic orbitals (PAOs), and (c) compaction of the virtual space through a truncated pair natural orbital (PNO) basis. In this paper, we report on the implementation of an analytic scheme for the calculation of the first derivatives of the DLPNO-CC energy for basis set independent perturbations within the singles and doubles approximation (DLPNO-CCSD) for closed-shell molecules. Perturbation-independent one-particle density matrices have been implemented in order to account for the response of the CC wave function to the external perturbation. Orbital-relaxation effects due to external perturbation are not taken into account in the current implementation. We investigate in detail the dependence of the computed first-order electrical properties (e.g., dipole moment) on the three major truncation parameters used in a DLPNO-CC calculation, namely, the natural orbital occupation number cutoff used for the construction of the PNOs, the weak electron-pair cutoff, and the domain size cutoff. No additional truncation parameter has been introduced for property calculation. We present benchmark calculations on dipole moments for a set of 10 molecules consisting of 20-40 atoms. We demonstrate that 98%-99% accuracy relative to the canonical CCSD results can be consistently achieved in these calculations. However, this comes with the price of tightening the

Top-quark pair production at next-to-next-to-leading order QCD in electron positron collisions

Energy Technology Data Exchange (ETDEWEB)

Chen, Long [Institut für Theoretische Teilchenphysik und Kosmologie, RWTH Aachen University,52056 Aachen (Germany); Dekkers, Oliver [PRISMA Cluster of Excellence and Institut für Physik,Johannes-Gutenberg-Universität Mainz,55099 Mainz (Germany); Heisler, Dennis; Bernreuther, Werner [Institut für Theoretische Teilchenphysik und Kosmologie, RWTH Aachen University,52056 Aachen (Germany); Si, Zong-Guo [School of Physics, Shandong University,Jinan, Shandong 250100 (China)

2016-12-19

We set up a formalism, within the antenna subtraction framework, for computing the production of a massive quark-antiquark pair in electron positron collisions at next-to-next-to-leading order in the coupling α{sub s} of quantum chromodynamics at the differential level. Our formalism applies to the calculation of any infrared-safe observable. We apply this set-up to the production of top-quark top antiquark pairs in the continuum. We compute the production cross section and several distributions. We determine, in particular, the top-quark forward-backward asymmetry at order α{sub s}{sup 2}. Our result agrees with previous computations of this observable.

QCD pairing in primordial nuggets

Science.gov (United States)

Lugones, G.; Horvath, J. E.

2003-08-01

We analyze the problem of boiling and surface evaporation of quark nuggets in the cosmological quark-hadron transition. Recently, it has been shown that QCD pairing modifies the stability properties of strange quark matter. More specifically, strange quark matter in a color-flavor locked state was found to be absolutely stable for a much wider range of the parameters than ordinary unpaired strange quark matter (G. Lugones and J. E. Horvath, Phys. Rev. D, 66, 074017 (2002)). Assuming that primordial quark nuggets are actually formed we analyze the consequences of pairing on the rates of boiling and surface evaporation in order to determine whether they could have survived.

Glass-forming liquids: one or more "order" parameters"

DEFF Research Database (Denmark)

Bailey, Nicholas; Christensen, Tage Emil; Jakobsen, Bo

2008-01-01

We first summarize the classical arguments that the vast majority of glass-forming liquids require more than one ‘order' parameter for their description. Critiques against this conventional wisdom are then presented, and it is argued that the matter deserves to be reconsidered in the light...... that a description with a single "order" parameter applies to a good approximation whenever thermal equilibrium fluctuations of fundamental variables like energy and pressure are strongly correlated. Results from computer simulations showing that this is the case for a number of simple glass-forming liquids, as well...

Quasiclassical description of multi-band superconductors with two order parameters

Energy Technology Data Exchange (ETDEWEB)

Moor, Andreas

2014-05-19

This Thesis deals with multi-band superconductors with two order parameters, i.e., the superconductivity and the spin-density wave, also touching on one-band superconductors with a charge-density wave, as well as with only the superconducting order parameter. Quasiclassical description of suchlike structures is developed and applied to investigation of various effects, inter alia, the Josephson and the proximity effects, the Knight shift, the Larkin-Ovchinnikov-Fulde-Ferrell-like state, and the interplay of the order parameters in coexistence regime. The applicability of the developed approach to pnictides is discussed.

Electron spin resonance for the detection of long-range spin nematic order

Science.gov (United States)

Furuya, Shunsuke C.; Momoi, Tsutomu

2018-03-01

Spin nematic phase is a quantum magnetic phase characterized by a quadrupolar order parameter. Since the quadrupole operators are directly coupled to neither the magnetic field nor the neutron, currently, it is an important issue to develop a method for detecting the long-range spin nematic order. In this paper, we propose that electron spin resonance (ESR) measurements enable us to detect the long-range spin nematic order. We show that the frequency of the paramagnetic resonance peak in the ESR spectrum is shifted by the ferroquadrupolar order parameter together with other quantities. The ferroquadrupolar order parameter is extractable from the angular dependence of the frequency shift. In contrast, the antiferroquadrupolar order parameter is usually invisible in the frequency shift. Instead, the long-range antiferroquadrupolar order yields a characteristic resonance peak in the ESR spectrum, which we call a magnon-pair resonance peak. This resonance corresponds to the excitation of the bound magnon pair at the wave vector k =0 . Reflecting the condensation of bound magnon pairs, the field dependence of the magnon-pair resonance frequency shows a singular upturn at the saturation field. Moreover, the intensity of the magnon-pair resonance peak shows a characteristic angular dependence and it vanishes when the magnetic field is parallel to one of the axes that diagonalize the weak anisotropic interactions. We confirm these general properties of the magnon-pair resonance peak in the spin nematic phase by studying an S =1 bilinear-biquadratic model on the square lattice in the linear flavor-wave approximation. In addition, we argue applications to the S =1/2 frustrated ferromagnets and also the S =1/2 orthogonal dimer spin system SrCu2(BO3)2, both of which are candidate materials of spin nematics. Our theory for the antiferroquadrupolar ordered phase is consistent with many features of the magnon-pair resonance peak experimentally observed in the low

Solliton-like order parameter distributions in the critical region

Directory of Open Access Journals (Sweden)

A.V.Babich

2006-01-01

Full Text Available Some exact one-component order parameter distributions for the Michelson thermodynamic potential are obtained. The phase transition of second kind in Ginzburg-Landau type model is investigated. The exact partial distribution of the order parameter in the form of Jakobi elliptic function is obtained. The energy of this distribution is lower at some temperature interval than for the best known models.

New de-embedding structures for extracting the electrical parameters of a through-silicon-via pair

International Nuclear Information System (INIS)

Zhou Jing; Wan Lixi; Li Jun; Wang Huijuan; Dai Fengwei; Cao Liqiang; Yu Daquan; Guidotti, Daniel

2013-01-01

Two innovative de-embedding methods are proposed for extracting an electrical model for a through-silicon-via (TSV) pair consisting of a ground-signal (GS) structure. In addition, based on microwave network theory, a new solution scheme is developed for dealing with multiple solutions of the transfer matrix during the process of de-embedding. A unique solution is determined based on the amplitude and the phase characteristic of S parameters. In the first de-embedding method, a typical “π“ type model of the TSV pair is developed, which illustrates the need to allow for frequency dependence in the equivalent TSV pair Spice model. This de-embedding method is shown to be effective for extracting the electrical properties of the TSVs. The feasibility of a second de-embedding method is also investigated. (semiconductor integrated circuits)

Fluctuations of order parameters in the high Tc superconductors

International Nuclear Information System (INIS)

Das, M.P.; Saif, A.G.

1987-07-01

Recently we have proposed a phenomenological approach in terms of two coexisting macroscopic order parameters corresponding to the superconducting and insulating states and have discussed the electrodynamical responses of the superconducting ceramics. In this paper we discuss the fluctuations of the order parameters both in the static and in the dynamical situations in the mean field approach and obtain results for the electrical conductivity which possesses anomalies as in granular materials. (author). 22 refs

A universal order parameter for synchrony in networks of limit cycle oscillators

Science.gov (United States)

Schröder, Malte; Timme, Marc; Witthaut, Dirk

2017-07-01

We analyze the properties of order parameters measuring synchronization and phase locking in complex oscillator networks. First, we review network order parameters previously introduced and reveal several shortcomings: none of the introduced order parameters capture all transitions from incoherence over phase locking to full synchrony for arbitrary, finite networks. We then introduce an alternative, universal order parameter that accurately tracks the degree of partial phase locking and synchronization, adapting the traditional definition to account for the network topology and its influence on the phase coherence of the oscillators. We rigorously prove that this order parameter is strictly monotonously increasing with the coupling strength in the phase locked state, directly reflecting the dynamic stability of the network. Furthermore, it indicates the onset of full phase locking by a diverging slope at the critical coupling strength. The order parameter may find applications across systems where different types of synchrony are possible, including biological networks and power grids.

TEMPORAL ORDER OF DISEASE PAIRS AFFECTS SUBSEQUENT DISEASE TRAJECTORIES

DEFF Research Database (Denmark)

Beck, Mette K; Westergaard, David; Jensen, Anders Boeck

2016-01-01

order of appearance. We discuss these different types of disease co-occurrences, and use the two diseases "sleep apnea" and "diabetes" to showcase the approach which otherwise can be applied to any disease pair. We benefit from seven million electronic medical records covering the entire population...... of Denmark for more than 20 years. Sleep apnea is the most common sleep-related breathing disorder and it has previously been shown to be bidirectionally linked to diabetes, meaning that each disease increases the risk of acquiring the other. We confirm that there is no significant temporal relationship......, as approximately half of patients with both diseases are diagnosed with diabetes first. However, we also show that patients diagnosed with diabetes before sleep apnea have a higher disease burden compared to patients diagnosed with sleep apnea before diabetes. The study clearly demonstrates that it is not only...

Order parameters and synchronization of FitzHugh–Nagumo small-world networks

International Nuclear Information System (INIS)

Yan-Long, Li; Jun, Ma; Yan-Jun, Liu; Wei, Zhang

2009-01-01

This paper numerically investigates the order parameter and synchronisation in the small world connected FitzHugh–Nagumo excitable systems. The simulations show that the order parameter continuously decreases with increasing D, the quality of the synchronisation worsens for large noise intensity. As the coupling intensity goes up, the quality of the synchronisation worsens, and it finds that the larger rewiring probability becomes the larger order parameter. It obtains the complete phase diagram for a wide range of values of noise intensity D and control parameter g. (cross-disciplinary physics and related areas of science and technology)

Variances as order parameter and complexity measure for random Boolean networks

International Nuclear Information System (INIS)

Luque, Bartolo; Ballesteros, Fernando J; Fernandez, Manuel

2005-01-01

Several order parameters have been considered to predict and characterize the transition between ordered and disordered phases in random Boolean networks, such as the Hamming distance between replicas or the stable core, which have been successfully used. In this work, we propose a natural and clear new order parameter: the temporal variance. We compute its value analytically and compare it with the results of numerical experiments. Finally, we propose a complexity measure based on the compromise between temporal and spatial variances. This new order parameter and its related complexity measure can be easily applied to other complex systems

Variances as order parameter and complexity measure for random Boolean networks

Energy Technology Data Exchange (ETDEWEB)

Luque, Bartolo [Departamento de Matematica Aplicada y EstadIstica, Escuela Superior de Ingenieros Aeronauticos, Universidad Politecnica de Madrid, Plaza Cardenal Cisneros 3, Madrid 28040 (Spain); Ballesteros, Fernando J [Observatori Astronomic, Universitat de Valencia, Ed. Instituts d' Investigacio, Pol. La Coma s/n, E-46980 Paterna, Valencia (Spain); Fernandez, Manuel [Departamento de Matematica Aplicada y EstadIstica, Escuela Superior de Ingenieros Aeronauticos, Universidad Politecnica de Madrid, Plaza Cardenal Cisneros 3, Madrid 28040 (Spain)

2005-02-04

Several order parameters have been considered to predict and characterize the transition between ordered and disordered phases in random Boolean networks, such as the Hamming distance between replicas or the stable core, which have been successfully used. In this work, we propose a natural and clear new order parameter: the temporal variance. We compute its value analytically and compare it with the results of numerical experiments. Finally, we propose a complexity measure based on the compromise between temporal and spatial variances. This new order parameter and its related complexity measure can be easily applied to other complex systems.

Ordering dynamics of microscopic models with nonconserved order parameter of continuous symmetry

DEFF Research Database (Denmark)

Zhang, Z.; Mouritsen, Ole G.; Zuckermann, Martin J.

1993-01-01

crystals. For both models, which have a nonconserved order parameter, it is found that the linear scale, R(t), of the evolving order, following quenches to below the transition temperature, grows at late times in an effectively algebraic fashion, R(t)∼tn, with exponent values which are strongly temperature......Numerical Monte Carlo temperature-quenching experiments have been performed on two three-dimensional classical lattice models with continuous ordering symmetry: the Lebwohl-Lasher model [Phys. Rev. A 6, 426 (1972)] and the ferromagnetic isotropic Heisenberg model. Both models describe a transition...... from a disordered phase to an orientationally ordered phase of continuous symmetry. The Lebwohl-Lasher model accounts for the orientational ordering properties of the nematic-isotropic transition in liquid crystals and the Heisenberg model for the ferromagnetic-paramagnetic transition in magnetic...

On the Interplay between Order Parameter Dynamics and System Parameter Dynamics in Human Perceptual-Cognitive-Behavioral Systems.

Science.gov (United States)

Frank, T D

2015-04-01

Previous research has demonstrated that perceiving, thinking, and acting are human activities that correspond to self-organized patterns. The emergence of such patterns can be completely described in terms of the dynamics of the pattern amplitudes, which are referred to as order parameters. The patterns emerge at bifurcations points when certain system parameters internal and external to a human agent exceed critical values. At issue is how one might study the order parameter dynamics for sequences of consecutive, emergent perceptual, cognitive, or behavioral activities. In particular, these activities may in turn impact the system parameters that have led to the emergence of the activities in the first place. This interplay between order parameter dynamics and system parameter dynamics is discussed in general and formulated in mathematical terms. Previous work that has made use of this two-tiered framework of order parameter and system parameter dynamics are briefly addressed. As an application, a model for perception under functional fixedness is presented. Finally, it is argued that the phenomena that emerge in this framework and can be observed when human agents perceive, think, and act are just as likely to occur in pattern formation systems of the inanimate world. Consequently, these phenomena do not necessarily have a neurophysiological basis but should instead be understood from the perspective of the theory of self-organization.

Riccati-parameter solutions of nonlinear second-order ODEs

International Nuclear Information System (INIS)

Reyes, M A; Rosu, H C

2008-01-01

It has been proven by Rosu and Cornejo-Perez (Rosu and Cornejo-Perez 2005 Phys. Rev. E 71 046607, Cornejo-Perez and Rosu 2005 Prog. Theor. Phys. 114 533) that for some nonlinear second-order ODEs it is a very simple task to find one particular solution once the nonlinear equation is factorized with the use of two first-order differential operators. Here, it is shown that an interesting class of parametric solutions is easy to obtain if the proposed factorization has a particular form, which happily turns out to be the case in many problems of physical interest. The method that we exemplify with a few explicitly solved cases consists in using the general solution of the Riccati equation, which contributes with one parameter to this class of parametric solutions. For these nonlinear cases, the Riccati parameter serves as a 'growth' parameter from the trivial null solution up to the particular solution found through the factorization procedure

N-representability of the Jastrow wave function pair density of the lowest-order.

Science.gov (United States)

Higuchi, Katsuhiko; Higuchi, Masahiko

2017-08-08

Conditions for the N-representability of the pair density (PD) are needed for the development of the PD functional theory. We derive sufficient conditions for the N-representability of the PD that is calculated from the Jastrow wave function within the lowest order. These conditions are used as the constraints on the correlation function of the Jastrow wave function. A concrete procedure to search the suitable correlation function is also presented.

The Order Parameter in a Spin Glass

NARCIS (Netherlands)

Enter, A.C.D. van; Griffiths, Robert B.

1983-01-01

Various possible precise definitions of an Edwards-Anderson type of order parameter for an Ising model spin glass are considered, using boundary conditions for a finite system, states of an infinite system, and a duplicate-system approach. Several of these definitions are shown to yield identical

Half-integer flux quantum effect in cuprate superconductors - a probe of pairing symmetry

International Nuclear Information System (INIS)

Tsuei, C.C.; Kirtley, J.R.; Gupta, A.; Sun, J.Z.; Moler, K.A.; Wang, J.H.

1996-01-01

Based on macroscopic quantum coherence effects arising from pair tunneling and flux quantization, a series of tricrystal experiments have been designed and carried out to test the order parameter symmetry in high-T c cuprate superconductors. By using a scanning SQUID microscope, we have directly and non-invasively observed the spontaneously generated half-integer flux quantum effect in controlled-orientation tricrystal cuprate superconducting systems. The presence or absence of the half-integer flux quantum effect as a function of the tricrystal geometry allows us to prove that the order parameter symmetry in the YBCO and Tl2201 systems is consistent with that of the d x 2 -y 2 pair state. (orig.)

The CP-violating 2HDM in light of a strong first order electroweak phase transition and implications for Higgs pair production

Science.gov (United States)

Basler, P.; Mühlleitner, M.; Wittbrodt, J.

2018-03-01

We investigate the strength of the electroweak phase transition (EWPT) within the CP-violating 2-Higgs-Doublet Model (C2HDM). The 2HDM is a simple and well-studied model, which can feature CP violation at tree level in its extended scalar sector. This makes it, in contrast to the Standard Model (SM), a promising candidate for explaining the baryon asymmetry of the universe through electroweak baryogenesis. We apply a renormalisation scheme which allows efficient scans of the C2HDM parameter space by using the loop-corrected masses and mixing matrix as input parameters. This procedure enables us to investigate the possibility of a strong first order EWPT required for baryogenesis and study its phenomenological implications for the LHC. Like in the CP-conserving (real) 2HDM (R2HDM) we find that a strong EWPT favours mass gaps between the non-SM-like Higgs bosons. These lead to prominent final states comprised of gauge+Higgs bosons or pairs of Higgs bosons. In contrast to the R2HDM, the CP-mixing of the C2HDM also favours approximately mass degenerate spectra with dominant decays into SM particles. The requirement of a strong EWPT further allows us to distinguish the C2HDM from the R2HDM using the signal strengths of the SM-like Higgs boson. We additionally find that a strong EWPT requires an enhancement of the SM-like trilinear Higgs coupling at next-to-leading order (NLO) by up to a factor of 2.4 compared to the NLO SM coupling, establishing another link between cosmology and collider phenomenology. We provide several C2HDM benchmark scenarios compatible with a strong EWPT and all experimental and theoretical constraints. We include the dominant branching ratios of the non-SM-like Higgs bosons as well as the Higgs pair production cross section of the SM-like Higgs boson for every benchmark point. The pair production cross sections can be substantially enhanced compared to the SM and could be observable at the high-luminosity LHC, allowing access to the trilinear

Wigner function and tomogram of the pair coherent state

International Nuclear Information System (INIS)

Meng, Xiang-Guo; Wang, Ji-Suo; Fan, Hong-Yi

2007-01-01

Using the entangled state representation of Wigner operator and the technique of integration within an ordered product (IWOP) of operators, the Wigner function of the pair coherent state is derived. The variations of the Wigner function with the parameters α and q in the ρ-γ phase space are discussed. The physical meaning of the Wigner function for the pair coherent state is given by virtue of its marginal distributions. The tomogram of the pair coherent state is calculated with the help of the Radon transform between the Wigner operator and the projection operator of the entangled state |η 1 ,η 2 ,τ 1 ,τ 2 >

Hybrid superconducting-magnetic memory device using competing order parameters.

Science.gov (United States)

Baek, Burm; Rippard, William H; Benz, Samuel P; Russek, Stephen E; Dresselhaus, Paul D

2014-05-28

In a hybrid superconducting-magnetic device, two order parameters compete, with one type of order suppressing the other. Recent interest in ultra-low-power, high-density cryogenic memories has spurred new efforts to simultaneously exploit superconducting and magnetic properties so as to create novel switching elements having these two competing orders. Here we describe a reconfigurable two-layer magnetic spin valve integrated within a Josephson junction. Our measurements separate the suppression in the superconducting coupling due to the exchange field in the magnetic layers, which causes depairing of the supercurrent, from the suppression due to the stray magnetic field. The exchange field suppression of the superconducting order parameter is a tunable and switchable behaviour that is also scalable to nanometer device dimensions. These devices demonstrate non-volatile, size-independent switching of Josephson coupling, in magnitude as well as phase, and they may enable practical nanoscale superconducting memory devices.

Tricritical behaviour in the phase transition induced by electron-hole pairing

International Nuclear Information System (INIS)

Crisan, M.

1980-01-01

The electron-hole pairing, which is possible in metals or semiconductors, can give condensed phases with two order parameters. If the coupling between the two order parameters is considered, the free energy functional is similar with the free energy of a n-component spin system with cubic anisotropy. Using the Wagner hypothesis (tricritical scaling) the non-linear scaling fields have been calculated. In order to perform the calculation of the nonlinear fields we used the method given by Rudnick and Nelson to solve the recursion relations for the 4-epsilon-dimensional system with n=6 components. The present calculation in the frame-work of the renormalization-group approach confirms the result obtained in the mean-field theory that the coupling of the two order parameters induces a first order phase transition. (author)

A pair of new moisture-dynamic diagnostic parameters for heavy rain location

Science.gov (United States)

Yuan, Kai; Zhu, Zhiwei; Li, Ming

2018-06-01

In this study, the regional persistent heavy rain process occurred in the middle and lower reaches of the Yangtze River valley from 30 June 2016 to 7 July 2016 is analyzed. We find that the pure dynamic parameters [e.g., vorticity ( V) and divergence ( D)] and two-dimensional moisture-dynamic parameters [e.g., moist vorticity ( MV), moist divergence ( MD)] have difficulty in capturing the rainfall location during such a critical process. Given the poor performance of these traditional parameters, a pair of new parameters [namely, one-dimensional moist vorticity ( ODMV) and one-dimensional moist divergence ( ODMD)] based on low-level jet is proposed for diagnosing heavy rain location. The results show that (1) ODMV and ODMD have better relations with rain belt in terms of spatial distribution. Precipitation occurs in positive (negative) region of ODMV ( ODMD), and heavy rainfall accurately locates in the positive (negative) center of ODMV ( ODMD); (2) ODMV and ODMD also have good correlation with the precipitation in terms of temporal variation (significant at the 99% confidence level). When ODMV ( ODMD) is in strong positive (negative) phase, precipitation is large, and vice versa; (3) the threat score of ODMV and ODMD for the areal-mean rainfall is improved by 119% and 16%, respectively, compared to V/ D and MV/ MD. It is anticipated that the proposed new parameters would facilitate the skills of diagnosing and forecasting the heavy rainfall.

Third-order QCD corrections to heavy quark pair production near threshold

Energy Technology Data Exchange (ETDEWEB)

Schuller, Kurt

2008-11-07

The measurement of the top quark mass is an important task at the future International Linear Collider. The most promising process is the top quark pair production in the threshold region. In this region the top quarks behave non-relativistically and a perturbative treatment using effective field theories is possible. Current second order theoretical predictions in a fixed order approach show an uncertainty which is bigger than the expected experimental errors. Therefore, an improvement of the cross section calculation is desirable. There are two ways to incorporate higher order effects, one is to calculate the full next order in the fixed order approach, another possibility is to resum large logarithms. In this work, the fixed order calculation has been extended to the third order in perturbation theory for the QCD corrections. The result is a strongly improved scale behavior and a better understanding of heavy quarkonium systems. The Green function result is given in a semi-analytic form. The energy levels and wave functions for heavy quarkonium states have been calculated from the poles of the Green function and are presented for arbitrary quantum number n. The results have been implemented in a Mathematica program which makes the data easily accessible. Once some missing matching coefficients are calculated, and a complete electroweak calculation is available, the results of this work can be used to improve the precision of the top quark mass measurement to an uncertainty of less than 50 MeV. An inclusion of initial state radiation and beam effects are essential for a realistic observable. In the future, the results obtained could be used for a third order resummation of large logarithms. Further applications are also the extraction of the bottom quark mass with sum rules. (orig.)

On the restoration of symmetry in paired Fermion systems

International Nuclear Information System (INIS)

Flocard, H.

1997-01-01

We consider the problem of symmetry restoration as treated by the method of variation after projection (VAP) on good quantum numbers. We show that for compact groups, the convergence of the connected-linked expansion of the VAP kernels over the physically relevant interval of integration of the pairing gauge angle is not guaranteed. We propose instead a method which generates approximations of increasing precision which are periodic with respect to the gauge angle while differing from truncations of the Fourier expansion of the VAP kernels. For the projection on good particle number in paired fermion systems, this new approach is shown to be equivalent to an expansion in powers of the pairing tensor. For the lowest order approximation, an analytical integration over the gauge angle is performed explicitly. It provides the algebraic forms of the single particle Hamiltonian and of the pairing field entering generalized Hartree endash Fock endash Bogoljubov equations. Contrary to most approximations, the validity of the expressions for the energy and mean values of operators thus obtained is not a priori restricted where the fluctuation of the operator associated with the broken symmetry is large. We also derive the first-order correction to the pairing-order parameter. We test the quality of the proposed method on a non-trivial soluble model. copyright 1997 Academic Press, Inc

Model for pairing phase transition in atomic nuclei

International Nuclear Information System (INIS)

Schiller, A.; Guttormsen, M.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.

2002-01-01

A model is developed which allows the investigation and classification of the pairing phase transition in atomic nuclei. The regions of the parameter space are discussed for which a pairing phase transition can be observed. The model parameters include number of particles, attenuation of pairing correlations with increasing seniority, single-particle level spacing, and pairing gap parameter

Eliciting hyperparameters of prior distributions for the parameters of paired comparison models

Directory of Open Access Journals (Sweden)

Nasir Abbas

2013-02-01

Full Text Available Normal 0 false false false EN-US X-NONE AR-SA In the study of paired comparisons (PC, items may be ranked or issues may be prioritized through subjective assessment of certain judges. PC models are developed and then used to serve the purpose of ranking. The PC models may be studied through classical or Bayesian approach. Bayesian inference is a modern statistical technique used to draw conclusions about the population parameters. Its beauty lies in incorporating prior information about the parameters into the analysis in addition to current information (i.e. data. The prior and current information are formally combined to yield a posterior distribution about the population parameters, which is the work bench of the Bayesian statisticians. However, the problems the Bayesians face correspond to the selection and formal utilization of prior distribution. Once the type of prior distribution is decided to be used, the problem of estimating the parameters of the prior distribution (i.e. elicitation still persists. Different methods are devised to serve the purpose. In this study an attempt is made to use Minimum Chi-square (hence forth MCS for the elicitation purpose. Though it is a classical estimation technique, but is used here for the election purpose. The entire elicitation procedure is illustrated through a numerical data set.

Dual origin of pairing in nuclei

Energy Technology Data Exchange (ETDEWEB)

Idini, A. [University of Jyvaskyla, Department of Physics (Finland); Potel, G. [Michigan State University, National Superconducting Cyclotron Laboratory (United States); Barranco, F. [Escuela Superior de Ingenieros, Universidad de Sevilla, Departamento de Fìsica Aplicada III (Spain); Vigezzi, E., E-mail: enrico.vigezzi@mi.infn.it [INFN Sezione di Milano (Italy); Broglia, R. A. [Università di Milano, Dipartimento di Fisica (Italy)

2016-11-15

The pairing correlations of the nucleus {sup 120}Sn are calculated by solving the Nambu–Gor’kov equations, including medium polarization effects resulting from the interweaving of quasiparticles, spin and density vibrations, taking into account, within the framework of nuclear field theory (NFT), processes leading to self-energy and vertex corrections and to the induced pairing interaction. From these results one can not only demonstrate the inevitability of the dual origin of pairing in nuclei, but also extract information which can be used at profit to quantitatively disentangle the contributions to the pairing gap Δ arising from the bare and from the induced pairing interaction. The first is the strong {sup 1}S{sub 0} short-range NN potential resulting from meson exchange between nucleons moving in time reversal states within an energy range of hundreds of MeV from the Fermi energy. The second results from the exchange of vibrational modes between nucleons moving within few MeV from the Fermi energy. Short- (v{sub p}{sup bare}) and long-range (v{sub p}{sup ind}) pairing interactions contribute essentially equally to nuclear Cooper pair stability. That is to the breaking of gauge invariance in open-shell superfluid nuclei and thus to the order parameter, namely to the ground state expectation value of the pair creation operator. In other words, to the emergent property of generalized rigidity in gauge space, and associated rotational bands and Cooper pair tunneling between members of these bands.

Dual origin of pairing in nuclei

Science.gov (United States)

Idini, A.; Potel, G.; Barranco, F.; Vigezzi, E.; Broglia, R. A.

2016-11-01

The pairing correlations of the nucleus 120Sn are calculated by solving the Nambu-Gor'kov equations, including medium polarization effects resulting from the interweaving of quasiparticles, spin and density vibrations, taking into account, within the framework of nuclear field theory (NFT), processes leading to self-energy and vertex corrections and to the induced pairing interaction. From these results one can not only demonstrate the inevitability of the dual origin of pairing in nuclei, but also extract information which can be used at profit to quantitatively disentangle the contributions to the pairing gap Δ arising from the bare and from the induced pairing interaction. The first is the strong 1 S 0 short-range NN potential resulting from meson exchange between nucleons moving in time reversal states within an energy range of hundreds of MeV from the Fermi energy. The second results from the exchange of vibrational modes between nucleons moving within few MeV from the Fermi energy. Short- ( v p bare) and long-range ( v p ind) pairing interactions contribute essentially equally to nuclear Cooper pair stability. That is to the breaking of gauge invariance in open-shell superfluid nuclei and thus to the order parameter, namely to the ground state expectation value of the pair creation operator. In other words, to the emergent property of generalized rigidity in gauge space, and associated rotational bands and Cooper pair tunneling between members of these bands.

Experimental First Order Pairing Phase Transition in Atomic Nuclei

International Nuclear Information System (INIS)

Moretto, L G; Larsen, A C; Giacoppo, F; Guttormsen, M; Siem, S

2015-01-01

The natural log of experimental nuclear level densities at low energy is linear with energy. This can be interpreted in terms of a nearly 1st order phase transition from a superfluid to an ideal gas of quasi particles. The transition temperature coincides with the BCS critical temperature and yields gap parameters in good agreement with the values extracted from even- odd mass differences from rotational states. This converging evidence supports the relevance of the BCS theory to atomic nuclei

Self-assembled fluids with order-parameter-dependent mobility: The ...

Indian Academy of Sciences (India)

The study is for quenching from an uncorrelated high temperature state into the Lifshitz line within the microemulsion phase. In the later stage of the ordering process, the structure factor exhibits multiscaling behavior with characteristic length scale (/ ln )1/2(2+3). The order-parameter-dependent mobility is found to slow ...

Crossover from phonon-mediated to repulsion-induced superconducting pairing with large momentum

International Nuclear Information System (INIS)

Belyavsky, V.I.; Kopaev, Yu.V.; Nguyen, N.T.; Togushova, Yu.N.

2005-01-01

There are asymmetric and symmetric solutions of the self-consistency equation which takes into account both phonon-mediated and Coulomb pairing interactions. The first of them leads to the order parameter with a nodal line and, in the case of pairing with large momentum, exists at any repulsive and attractive strengths. The second one arises if the attraction exceeds a level depending on the repulsion strength and dominates the pairing in the strong attraction limit. The competition of attraction and repulsion results in unusual isotope-effect exponent observed in the cuprates

Mesoscopic pairing without superconductivity

Science.gov (United States)

Hofmann, Johannes

2017-12-01

We discuss pairing signatures in mesoscopic nanowires with a variable attractive pairing interaction. Depending on the wire length, density, and interaction strength, these systems realize a simultaneous bulk-to-mesoscopic and BCS-BEC crossover, which we describe in terms of the parity parameter that quantifies the odd-even energy difference and generalizes the bulk Cooper pair binding energy to mesoscopic systems. We show that the parity parameter can be extracted from recent measurements of conductance oscillations in SrTiO3 nanowires by Cheng et al. [Nature (London) 521, 196 (2015), 10.1038/nature14398], where it marks the critical magnetic field that separates pair and single-particle currents. Our results place the experiment in the fluctuation-dominated mesoscopic regime on the BCS side of the crossover.

A counter-rotating vortex pair in inviscid fluid

Science.gov (United States)

Habibah, Ummu; Fukumoto, Yasuhide

2017-12-01

We study the motion of a counter-rotating vortex pair with the circulations ±Γ move in incompressible fluid. The assumption is made that the core is very thin, that is the core radius σ is much smaller than the vortex radius d such that ɛ = σ/d ≪ 1. With this condition, the method of matched asymptotic expansion is employed. The solutions of the Navier-Stokes equations and the Biot-Savart law, regarding the inner and outer solutions respectively, are constructed in the form of a small parameter. An asymptotic expansion of the Biot-Savart law near the vortex core provides with the matching condition for an asymptotic expansion for limiting the Navier-Stokes equations for large radius r. The general formula of an anti-parallel vortex pair is established. At leading order O(ɛ0), we apply the special case in inviscid fluid, the Rankine vortex, a circular vortex of uniform vorticity. Furthermore at leading order O(ɛ5) we show the traveling speed of a vortex pair.

Mechanical properties of ordered alloys

International Nuclear Information System (INIS)

Kroupa, F.

1977-06-01

A survey is given of the metallophysical fundamentals of the mechanical properties of ordered two-phase alloys. Alloys of this type have a superlattice structure in a substitution mixed crystal. Ordering is achieved by slow cooling or by annealing below the critical temperature, during which ordering domains (antiphase domains) are formed. At a high degree of ordering, the dislocations are concentrated to form pairs, so-called super-dislocations. The mechanical properties may be selectively changed by varying different parameters (size of the ordering domains, degree of ordering, energy of the antiphase boundaries) by a special composition and heat treatment.(GSC) [de

Kernel methods for interpretable machine learning of order parameters

Science.gov (United States)

Ponte, Pedro; Melko, Roger G.

2017-11-01

Machine learning is capable of discriminating phases of matter, and finding associated phase transitions, directly from large data sets of raw state configurations. In the context of condensed matter physics, most progress in the field of supervised learning has come from employing neural networks as classifiers. Although very powerful, such algorithms suffer from a lack of interpretability, which is usually desired in scientific applications in order to associate learned features with physical phenomena. In this paper, we explore support vector machines (SVMs), which are a class of supervised kernel methods that provide interpretable decision functions. We find that SVMs can learn the mathematical form of physical discriminators, such as order parameters and Hamiltonian constraints, for a set of two-dimensional spin models: the ferromagnetic Ising model, a conserved-order-parameter Ising model, and the Ising gauge theory. The ability of SVMs to provide interpretable classification highlights their potential for automating feature detection in both synthetic and experimental data sets for condensed matter and other many-body systems.

Inferring microRNA regulation of mRNA with partially ordered samples of paired expression data and exogenous prediction algorithms.

Directory of Open Access Journals (Sweden)

Brian Godsey

Full Text Available MicroRNAs (miRs are known to play an important role in mRNA regulation, often by binding to complementary sequences in "target" mRNAs. Recently, several methods have been developed by which existing sequence-based target predictions can be combined with miR and mRNA expression data to infer true miR-mRNA targeting relationships. It has been shown that the combination of these two approaches gives more reliable results than either by itself. While a few such algorithms give excellent results, none fully addresses expression data sets with a natural ordering of the samples. If the samples in an experiment can be ordered or partially ordered by their expected similarity to one another, such as for time-series or studies of development processes, stages, or types, (e.g. cell type, disease, growth, aging, there are unique opportunities to infer miR-mRNA interactions that may be specific to the underlying processes, and existing methods do not exploit this. We propose an algorithm which specifically addresses [partially] ordered expression data and takes advantage of sample similarities based on the ordering structure. This is done within a Bayesian framework which specifies posterior distributions and therefore statistical significance for each model parameter and latent variable. We apply our model to a previously published expression data set of paired miR and mRNA arrays in five partially ordered conditions, with biological replicates, related to multiple myeloma, and we show how considering potential orderings can improve the inference of miR-mRNA interactions, as measured by existing knowledge about the involved transcripts.

Effects of temperature and electric field on order parameters in ferroelectric hexagonal manganites

Science.gov (United States)

Zhang, C. X.; Yang, K. L.; Jia, P.; Lin, H. L.; Li, C. F.; Lin, L.; Yan, Z. B.; Liu, J.-M.

2018-03-01

In Landau-Devonshire phase transition theory, the order parameter represents a unique property for a disorder-order transition at the critical temperature. Nevertheless, for a phase transition with more than one order parameter, such behaviors can be quite different and system-dependent in many cases. In this work, we investigate the temperature (T) and electric field (E) dependence of the two order parameters in improper ferroelectric hexagonal manganites, addressing the phase transition from the high-symmetry P63/mmc structure to the polar P63cm structure. It is revealed that the trimerization as the primary order parameter with two components: the trimerization amplitude Q and phase Φ, and the spontaneous polarization P emerging as the secondary order parameter exhibit quite different stability behaviors against various T and E. The critical exponents for the two parameters Q and P are 1/2 and 3/2, respectively. As temperature increases, the window for the electric field E enduring the trimerization state will shrink. An electric field will break the Z2 part of the Z2×Z3 symmetry. The present work may shed light on the complexity of the vortex-antivortex domain structure evolution near the phase transition temperature.

Order parameter fluctuations at a critical point - an exact result about percolation -

International Nuclear Information System (INIS)

Botet, Robert

2011-01-01

The order parameter of the system in the critical state, is expected to undergo large non-Gaussian fluctuations. However, almost nothing is known about the mathematical forms of the possible probability distributions of the order parameter. A remarkable exception is the site-percolation on the Bethe lattice, for which the complete order-parameter distribution has been recently derived at the critical point. Surprisingly, it appears to be the Kolmogorov-Smirnov distribution, well known in very different areas of mathematical statistics. In the present paper, we explain first how this special distribution could appear naturally in the context of the critical systems, under the assumption (still virtually unstudied) of the exponential distribution of the number of domains of a given size. In a second part, we present for the first time the complete derivation of the order-parameter distribution for the critical percolation model on the Bethe lattice, thus completing a recent publication announcing this result.

Pair breaking and density of states in disordered superconductors

International Nuclear Information System (INIS)

Weinkauf, A.; Zittartz, J.

1975-01-01

It is shown that pair breaking occurs in a disordered superconductor due to spatial variations of the order parameter, although the system is time reversal invariant. The pair breaking effect is reflected by the occurence of some interesting fine structure in the one particle density of states. Discrete bound states and split-off impurity bands show up in the single impurity case and for very dilute alloys, respectively. For finite alloy concentrations the calculations are done within the CPA. Although principally important, the fine structure is concentrated in an energy range too narrow to be detected experimentally. (orig.) [de

Renormalization group analysis of order parameter fluctuations in fermionic superfluids

International Nuclear Information System (INIS)

Obert, Benjamin

2014-01-01

In this work fluctuation effects in two interacting fermion systems exhibiting fermionic s-wave superfluidity are analyzed with a modern renormalization group method. A description in terms of a fermion-boson theory allows an investigation of order parameter fluctuations already on the one-loop level. In the first project a quantum phase transition between a semimetal and a s-wave superfluid in a Dirac cone model is studied. The interplay between fermions and quantum critical fluctuations close to and at the quantum critical point at zero and finite temperatures are studied within a coupled fermion-boson theory. At the quantum critical point non-Fermi liquid and non-Gaussian behaviour emerge. Close to criticality several quantities as the susceptibility show a power law behaviour with critical exponents. We find an infinite correlation length in the entire semimetallic ground state also away from the quantum critical point. In the second project, the ground state of an s-wave fermionic superfluid is investigated. Here, the mutual interplay between fermions and order parameter fluctuations is studied, especially the impact of massless Goldstone fluctuations, which occur due to spontaneous breaking of the continuous U(1)-symmetry. Fermionic gap and bosonic order parameter are distinguished. Furthermore, the bosonic order parameter is decomposed in transverse and longitudinal fluctuations. The mixing between transverse and longitudinal fluctuations is included in our description. Within a simple truncation of the fermion-boson RG flow, we describe the fermion-boson theory for the first time in a consistent manner. Several singularities appear due the Goldstone fluctuations, which partially cancel due to symmetry. Our RG flow captures the correct infrared asymptotics of the system, where the collective excitations act as an interacting Bose gas. Lowest order Ward identities and the massless Goldstone mode are fulfilled in our truncation.

Electromagnetic lepton-pair production in relativistic collisions

International Nuclear Information System (INIS)

Albert, C.J.; Ernst, D.J.; Strayer, M.R.; Bottcher, C.

1991-01-01

Electromagnetic lepton-pair production in relativistic collisions is studied in an ab initio approach with no free parameters. After a semi-classical approximation to the relative motion of the two incident particles is made, the resulting second-order diagram is calculated using a Monte Carlo technique to evaluate the resulting seven-dimensional integral. We examine the case of electron-positron pair production in π - p collisions at p pi = 17 GeV. We find that a significant fraction of the measured pairs in this reaction are produced via the magnetic spin-flip current of the proton. Approaches, such as the equivalent photon approximation, which neglect this part of the current predict much too small a cross section. This feature is traced to the cuts imposed in taking the experimental data. Lepton-pair production in the scattering of 3 He, 4 He and 4 He, 4 He is proposed as a clean way of experimentally separating the spin-flip and non-flip processes; predictions are made for these systems

Infinitely robust order and local order-parameter tulips in Apollonian networks with quenched disorder

Science.gov (United States)

Kaplan, C. Nadir; Hinczewski, Michael; Berker, A. Nihat

2009-06-01

For a variety of quenched random spin systems on an Apollonian network, including ferromagnetic and antiferromagnetic bond percolation and the Ising spin glass, we find the persistence of ordered phases up to infinite temperature over the entire range of disorder. We develop a renormalization-group technique that yields highly detailed information, including the exact distributions of local magnetizations and local spin-glass order parameters, which turn out to exhibit, as function of temperature, complex and distinctive tulip patterns.

Coupling of order parameters, chirality, and interfacial structures in multiferroic materials.

Science.gov (United States)

Conti, Sergio; Müller, Stefan; Poliakovsky, Arkady; Salje, Ekhard K H

2011-04-13

We study optimal interfacial structures in multiferroic materials with a biquadratic coupling between two order parameters. We discover a new duality relation between the strong coupling and the weak coupling regime for the case of isotropic gradient terms. We analyze the phase diagram depending on the coupling constant and anisotropy of the gradient term, and show that in a certain regime the secondary order parameter becomes activated only in the interfacial region.

ON THE POLAR CAP CASCADE PAIR MULTIPLICITY OF YOUNG PULSARS

Energy Technology Data Exchange (ETDEWEB)

Timokhin, A. N.; Harding, A. K., E-mail: andrey.timokhin@nasa.gov [Astrophysics Science Division, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2015-09-10

We study the efficiency of pair production in polar caps of young pulsars under a variety of conditions to estimate the maximum possible multiplicity of pair plasma in pulsar magnetospheres. We develop a semi-analytic model for calculation of cascade multiplicity which allows efficient exploration of the parameter space and corroborate it with direct numerical simulations. Pair creation processes are considered separately from particle acceleration in order to assess different factors affecting cascade efficiency, with acceleration of primary particles described by recent self-consistent non-stationary model of pair cascades. We argue that the most efficient cascades operate in the curvature radiation/synchrotron regime, the maximum multiplicity of pair plasma in pulsar magnetospheres is ∼few × 10{sup 5}. The multiplicity of pair plasma in magnetospheres of young energetic pulsars weakly depends on the strength of the magnetic field and the radius of curvature of magnetic field lines and has a stronger dependence on pulsar inclination angle. This result questions assumptions about very high pair plasma multiplicity in theories of pulsar wind nebulae.

On top-pair hadro-production at next-to-next-to-leading order

International Nuclear Information System (INIS)

Moch, S.; Uwer, P.; Vogt, A.

2012-03-01

We study the QCD corrections at next-to-next-to-leading order (NNLO) to the cross section for the hadronic pair-production of top quarks. We present new results in the high-energy limit using the well-known framework of k t -factorization. We combine these findings with the known threshold corrections and present improved approximate NNLO results over the full kinematic range. This approach is employed to quantify the residual theoretical uncertainty of the approximate NNLO results which amounts to about 4% for the Tevatron and 5% for the LHC cross-section predictions. Our analytic results in the high-energy limit will provide an important check on future computations of the complete NNLO cross sections.

NMR determination of the order parameter in proton and deuteron glasses

International Nuclear Information System (INIS)

Blinc, R.; Dolinsek, J.; Zalar, B.

1989-01-01

The inhomogeneous broadening of the ND + deuteron, O-D--O deuteron and 87 Rb quadrapole perturbed NMR spectra in Rb 0.56 (ND 4 ) 0.44 D 2 PO 4 is used for a direct determination of the Edwards-Anderson pseudo-spin glass order parameter. The data provide strong support for a model where the basic difference between magnetic spin glasses and proton or deuteron glasses is the presence of an inherent random field resulting from substitutional disorder which linearly couples to the O-D--O pseudo spins. In these systems we do not deal with a transition from a paraelectric to a pseudo-spin glass phase but rather with a transition from an ergodic pseudo-spin glass phase with a single order parameter q to a non-ergodic pseudo-spin glass phase with an infinite number of order parameters. (author). 11 refs.; 6 figs

Electromagnetic heavy-lepton pair production in relativistic heavy-ion collisions

Energy Technology Data Exchange (ETDEWEB)

Senguel, M.Y. [Atakent Mahallesi, 3. Etap, Halkali-Kuecuekcekmece, Istanbul (Turkey); Gueclue, M.C.; Mercan, Oe.; Karakus, N.G. [istanbul Technical University, Faculty of Science and Letters, Istanbul (Turkey)

2016-08-15

We calculate the cross sections of electromagnetic productions of muon- and tauon-pair productions from the ultra-relativistic heavy ion collisions. Since the Compton wavelengths of muon and tauon are comparable to the radius of the colliding ions, nuclear form factors play important roles for calculating the cross sections. Recent measurement (Abrahamyan et al., Phys Rev Lett 108:112502, 2012) indicates that the neutrons are differently distributed from the protons; therefore this affects the cross section of the heavy-lepton pair production. In order to see the effects of the neutron distributions in the nucleus, we used analytical expression of the Fourier transforms of the Wood-Saxon distribution. Cross section calculations show that the Wood-Saxon distribution function is more sensitive to the parameter R compared to the parameter a. (orig.)

Pair production of Dirac particles in a d + 1-dimensional noncommutative space-time

Energy Technology Data Exchange (ETDEWEB)

Ousmane Samary, Dine [Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada); University of Abomey-Calavi, International Chair in Mathematical Physics and Applications (ICMPA-UNESCO Chair), Cotonou (Benin); N' Dolo, Emanonfi Elias; Hounkonnou, Mahouton Norbert [University of Abomey-Calavi, International Chair in Mathematical Physics and Applications (ICMPA-UNESCO Chair), Cotonou (Benin)

2014-11-15

This work addresses the computation of the probability of fermionic particle pair production in d + 1-dimensional noncommutative Moyal space. Using Seiberg-Witten maps, which establish relations between noncommutative and commutative field variables, up to the first order in the noncommutative parameter θ, we derive the probability density of vacuum-vacuum pair production of Dirac particles. The cases of constant electromagnetic, alternating time-dependent, and space-dependent electric fields are considered and discussed. (orig.)

Finite-thickness effect on speed of a counter-rotating vortex pair at high Reynolds numbers

Science.gov (United States)

Habibah, Ummu; Nakagawa, Hironori; Fukumoto, Yasuhide

2018-03-01

We establish a general formula for the translational speed of a counter-rotating vortex pair, valid for thick cores, moving in an incompressible fluid with and without viscosity. We extend to higher order the method of matched asymptotic expansions developed by Ting and Tung (1965 Phys. Fluids 8 1039–51). The solution of the Euler or the Navier–Stokes equations is constructed in the form of a power series in a small parameter, the ratio of the core radius to the distance between the core centers. For a viscous vortex pair, the small parameter should be \\sqrt{ν /{{Γ }}} where ν is the kinematic viscosity of the fluid and Γ is the circulation of each vortex. A correction due to the effect of finite thickness of the vortices to the traveling speed makes its appearance at fifth order. A drastic simplification is achieved of expressing it solely in terms of the strength of the second-order quadrupole field associated with the elliptical deformation of the core. For a viscous vortex pair, we exploit the conservation law for the hydrodynamic impulse to derive the growth of the distance between the vortices, which is cubic in time.

Order parameters in lanthanum gallate lightly doped with manganese and paramagnetic resonance

Science.gov (United States)

Vazhenin, V. A.; Potapov, A. P.; Artyomov, M. Yu.; Guseva, V. B.

2010-09-01

The Cr3+ centers have been revealed, transitions at room temperature have been identified, and spin Hamiltonian parameters have been determined for the Cr3+ and Fe3+ triclinic centers in lanthanum gallate lightly doped with manganese. The principal axes of the fourth-rank fine-structure tensor for the Fe3+ triclinic centers have been established and used to determine the order parameters, i.e., the angles of rotation of oxygen octahedra of lanthanum gallate with respect to the perovskite structure. The order parameter in the rhombohedral phase has been estimated.

Cooper pairs' magnetic moment in MCFL color superconductivity

International Nuclear Information System (INIS)

Feng Bo; Ferrer, Efrain J.; Incera, Vivian de la

2011-01-01

We investigate the effect of the alignment of the magnetic moments of Cooper pairs of charged quarks that form at high density in three-flavor quark matter. The high-density phase of this matter in the presence of a magnetic field is known to be the Magnetic Color-Flavor-Locked (MCFL) phase of color superconductivity. We derive the Fierz identities of the theory and show how the explicit breaking of the rotational symmetry by the uniform magnetic field opens new channels of interactions and allows the formation of a new diquark condensate. The new order parameter is a spin-1 condensate proportional to the component in the field direction of the average magnetic moment of the pairs of charged quarks. The magnitude of the spin-1 condensate becomes comparable to the larger of the two scalar gaps in the region of large fields. The existence of the spin-1 condensate is unavoidable, as in the presence of a magnetic field there is no solution of the gap equations with nonzero scalar gaps and zero magnetic moment condensate. This is consistent with the fact that the extra condensate does not break any symmetry that has not already been broken by the known MCFL gaps. The spin-1 condensate enhances the condensation energy of pairs formed by charged quarks and the magnetization of the system. We discuss the possible consequences of the new order parameter on the issue of the chromomagnetic instability that appears in color superconductivity at moderate density.

Ginsburg-Landau theory of two antagonistic order parameters: magnetism and superconductivity

International Nuclear Information System (INIS)

Suhl, H.

1978-01-01

An attempt is made to construct a Ginsburg-Landau theory of so-called magnetic superconductors. Two order parameters, the magnetization field and the gap function, are introduced in such a way as to inhibit each others growth. It is found that the non-local character of the superconducting order parameter must be taken into account in any evaluation of effects of the critical magnetic fluctuations. Some predictions are made within the limits of Ornstein-Zoernicke-like fluctuation theory and some comparison is made with available data. (Auth.)

Coexistence of pairing gaps in three-component Fermi gases

International Nuclear Information System (INIS)

Nummi, O H T; Kinnunen, J J; Toermae, P

2011-01-01

We study a three-component superfluid Fermi gas in a spherically symmetric harmonic trap using the Bogoliubov-deGennes method. We predict a coexistence phase in which two pairing field order parameters are simultaneously non-zero, in stark contrast to studies performed for trapped gases using local density approximation. We also discuss the role of atom number conservation in the context of a homogeneous system.

Parameters and Fractional Differentiation Orders Estimation for Linear Continuous-Time Non-Commensurate Fractional Order Systems

KAUST Repository

Belkhatir, Zehor; Laleg-Kirati, Taous-Meriem

2017-01-01

This paper proposes a two-stage estimation algorithm to solve the problem of joint estimation of the parameters and the fractional differentiation orders of a linear continuous-time fractional system with non-commensurate orders. The proposed algorithm combines the modulating functions and the first-order Newton methods. Sufficient conditions ensuring the convergence of the method are provided. An error analysis in the discrete case is performed. Moreover, the method is extended to the joint estimation of smooth unknown input and fractional differentiation orders. The performance of the proposed approach is illustrated with different numerical examples. Furthermore, a potential application of the algorithm is proposed which consists in the estimation of the differentiation orders of a fractional neurovascular model along with the neural activity considered as input for this model.

Parameters and Fractional Differentiation Orders Estimation for Linear Continuous-Time Non-Commensurate Fractional Order Systems

KAUST Repository

Belkhatir, Zehor

2017-05-31

This paper proposes a two-stage estimation algorithm to solve the problem of joint estimation of the parameters and the fractional differentiation orders of a linear continuous-time fractional system with non-commensurate orders. The proposed algorithm combines the modulating functions and the first-order Newton methods. Sufficient conditions ensuring the convergence of the method are provided. An error analysis in the discrete case is performed. Moreover, the method is extended to the joint estimation of smooth unknown input and fractional differentiation orders. The performance of the proposed approach is illustrated with different numerical examples. Furthermore, a potential application of the algorithm is proposed which consists in the estimation of the differentiation orders of a fractional neurovascular model along with the neural activity considered as input for this model.

Transition from Sign-Reversed to Sign-Preserved Cooper-Pairing Symmetry in Sulfur-Doped Iron Selenide Superconductors.

Science.gov (United States)

Wang, Qisi; Park, J T; Feng, Yu; Shen, Yao; Hao, Yiqing; Pan, Bingying; Lynn, J W; Ivanov, A; Chi, Songxue; Matsuda, M; Cao, Huibo; Birgeneau, R J; Efremov, D V; Zhao, Jun

2016-05-13

An essential step toward elucidating the mechanism of superconductivity is to determine the sign or phase of the superconducting order parameter, as it is closely related to the pairing interaction. In conventional superconductors, the electron-phonon interaction induces attraction between electrons near the Fermi energy and results in a sign-preserved s-wave pairing. For high-temperature superconductors, including cuprates and iron-based superconductors, prevalent weak coupling theories suggest that the electron pairing is mediated by spin fluctuations which lead to repulsive interactions, and therefore that a sign-reversed pairing with an s_{±} or d-wave symmetry is favored. Here, by using magnetic neutron scattering, a phase sensitive probe of the superconducting gap, we report the observation of a transition from the sign-reversed to sign-preserved Cooper-pairing symmetry with insignificant changes in T_{c} in the S-doped iron selenide superconductors K_{x}Fe_{2-y}(Se_{1-z}S_{z})_{2}. We show that a rather sharp magnetic resonant mode well below the superconducting gap (2Δ) in the undoped sample (z=0) is replaced by a broad hump structure above 2Δ under 50% S doping. These results cannot be readily explained by simple spin fluctuation-exchange pairing theories and, therefore, multiple pairing channels are required to describe superconductivity in this system. Our findings may also yield a simple explanation for the sometimes contradictory data on the sign of the superconducting order parameter in iron-based materials.

A positive-weight next-to-leading-order Monte Carlo for Z pair hadroproduction

International Nuclear Information System (INIS)

Nason, Paolo; Ridolfi, Giovanni

2006-01-01

We present a first application of a previously published method for the computation of QCD processes that is accurate at next-to-leading order, and that can be interfaced consistently to standard shower Monte Carlo programs. We have considered Z pair production in hadron-hadron collisions, a process whose complexity is sufficient to test the general applicability of the method. We have interfaced our result to the HERWIG and PYTHIA shower Monte Carlo programs. Previous work on next-to-leading order corrections in a shower Monte Carlo (the MC-NLO program) may involve the generation of events with negative weights, that are avoided with the present method. We have compared our results with those obtained with MC-NLO, and found remarkable consistency. Our method can also be used as a standalone, alternative implementation of QCD corrections, with the advantage of positivity, improved convergence, and next-to-leading logarithmic accuracy in the region of small transverse momentum of the radiated parton

Random textures of the order parameter of superfluid sup 3 He-B in aerogel

CERN Document Server

Fomin, Yu A

2002-01-01

The scheme for describing the properties of the superfluid sup 3 He in the aerogel is proposed in accordance with the Ginzburg and Landau theory. The aerogel effect on the order parameter is described by the random tensor field. This field exerts desorientation effect on the order parameter in the sup 3 He A-phase, but it does not influence the order parameter orientation in the B-phase, if there is no magnetic field. The change in the order parameter texture, originating in the B-phase in the aerogel in the magnetic field, is considered. Fluctuations of the sup 3 He-B anisotropy axis direction are correlated on the length, inversely proportional to the field intensity and having the macroscopic scale

Two-Order-Parameter Description of Liquids: Critical Phenomena and Phase Separation of Supercooled Liquids

OpenAIRE

Tanaka, Hajime

1997-01-01

Because of the isotropic and disordered nature of liquids, the anisotropy hidden in intermolecular interactions are often neglected. Accordingly, the order parameter describing a simple liquid has so far been believed to be only density. In contrast to this common sense, we propose that two order parameters, namely, density and bond order parameters, are required to describe the phase behavior of liquids since they intrinsically tend to form local bonds. This model gives us clear physical exp...

Chaos and order in models of black hole pairs

International Nuclear Information System (INIS)

Levin, Janna

2006-01-01

Chaos in the orbits of black hole pairs has by now been confirmed by several independent groups. While the chaotic behavior of binary black hole orbits is no longer argued, it remains difficult to quantify the importance of chaos to the evolutionary dynamics of a pair of comparable mass black holes. None of our existing approximations are robust enough to offer convincing quantitative conclusions in the most highly nonlinear regime. It is intriguing to note that, in three different approximations to a black hole pair built of a spinning black hole and a nonspinning companion, two approximations exhibit chaos and one approximation does not. The fully relativistic scenario of a spinning test mass around a Schwarzschild black hole shows chaos, as does the post-Newtonian Lagrangian approximation. However, the approximately equivalent post-Newtonian Hamiltonian approximation does not show chaos when only one body spins. It is well known in dynamical systems theory that one system can be regular while an approximately related system is chaotic, so there is no formal conflict. However, the physical question remains: Is there chaos for comparable mass binaries when only one object spins? We are unable to answer this question given the poor convergence of the post-Newtonian approximation to the fully relativistic system. A resolution awaits better approximations that can be trusted in the highly nonlinear regime

Efficient and accurate local approximations to coupled-electron pair approaches: An attempt to revive the pair natural orbital method.

Science.gov (United States)

Neese, Frank; Wennmohs, Frank; Hansen, Andreas

2009-03-21

Coupled-electron pair approximations (CEPAs) and coupled-pair functionals (CPFs) have been popular in the 1970s and 1980s and have yielded excellent results for small molecules. Recently, interest in CEPA and CPF methods has been renewed. It has been shown that these methods lead to competitive thermochemical, kinetic, and structural predictions. They greatly surpass second order Moller-Plesset and popular density functional theory based approaches in accuracy and are intermediate in quality between CCSD and CCSD(T) in extended benchmark studies. In this work an efficient production level implementation of the closed shell CEPA and CPF methods is reported that can be applied to medium sized molecules in the range of 50-100 atoms and up to about 2000 basis functions. The internal space is spanned by localized internal orbitals. The external space is greatly compressed through the method of pair natural orbitals (PNOs) that was also introduced by the pioneers of the CEPA approaches. Our implementation also makes extended use of density fitting (or resolution of the identity) techniques in order to speed up the laborious integral transformations. The method is called local pair natural orbital CEPA (LPNO-CEPA) (LPNO-CPF). The implementation is centered around the concepts of electron pairs and matrix operations. Altogether three cutoff parameters are introduced that control the size of the significant pair list, the average number of PNOs per electron pair, and the number of contributing basis functions per PNO. With the conservatively chosen default values of these thresholds, the method recovers about 99.8% of the canonical correlation energy. This translates to absolute deviations from the canonical result of only a few kcal mol(-1). Extended numerical test calculations demonstrate that LPNO-CEPA (LPNO-CPF) has essentially the same accuracy as parent CEPA (CPF) methods for thermochemistry, kinetics, weak interactions, and potential energy surfaces but is up to 500

Magnetic phase transitions with incommensurate structures in systems with coupled order parameters

International Nuclear Information System (INIS)

Izyumov, Yu.A.; Laptev, V.M.; Petrov, S.B.

1984-01-01

Modulated magnetic phases are investigated for the case when symmetry does not allow linear by gradients Lifshits invariants and magnetic momenta are converted by two irreducible representations. Possible phase diagrams with participation of incommensurable phases are plotted on the base of Ginsburg-Landau functional for 2 bound parameters of the order. The role of the highest harmonics in spatial distribution of the order parameters is clarified on the example of magnetic phase transitions in Er

A second order QCD effect. quark-quark bremsstrahlung contribution to transverse momentum of lepton pairs

International Nuclear Information System (INIS)

Chaichian, M.; Hayashi, M.; Honkaranta, T.

1980-01-01

We consider in QCD the second order, in gluon-quark coupling constant, contribution of the quark-quark scatte-ring (bremsstrahlung) to the transverse momentum distribution of muon pairs produced in proton-proton collisions. In certain kinematical regions accesible to experimental tests, this contribution is quite large in comparison with the first order calculations. This happens for a specific choice of scale violating structure functions which fit the deep inelastic data. Thus the first order QCD calcula-tion alone is not conclusive in trying to fit the data -one must necessarily check the effect of the second order quark-quark scattering as compared with the first order quark-gluon and the quark-antiquark scattering. This remark concerns also the case when in the first order diagrams the effect of primordial transverse momentum of partons is included as well as the case when the first order is replaced by DDT type of formulae. Mass regularization and different prescriptions for the constant term in q → g + q vertex are considered. Results are presented for the energies √s=6.5, 27, 63, 800 GeV and are compared with experiment. Implications of these results for the detection of W +- -mesons via psub(T) distribution of their decay products μ +- in proton-proton collisions are mentioned. (author)

Pairing-bag excitations in small-coherence-length superconductors

International Nuclear Information System (INIS)

Bishop, A.R.; Lomdahl, P.S.; Schrieffer, J.R.; Trugman, S.A.

1988-01-01

Localized baglike solutions in the pairing theory of superconductivity are studied. Starting from the Bogoliubov--de Gennes equations on a two-dimensional square lattice for half-filled negative-U Hubbard model, cigar- and star-shaped bags are numerically obtained, inside of which the order parameter is reduced, self-consistently trapping an added quasiparticle. These nonlinear excitations are important when the coherence length is small as for the new high-temperature superconductors. Several experimental consequences are discussed

Molecular dynamics study of some non-hydrogen-bonding base pair DNA strands

Science.gov (United States)

Tiwari, Rakesh K.; Ojha, Rajendra P.; Tiwari, Gargi; Pandey, Vishnudatt; Mall, Vijaysree

2018-05-01

In order to elucidate the structural activity of hydrophobic modified DNA, the DMMO2-D5SICS, base pair is introduced as a constituent in different set of 12-mer and 14-mer DNA sequences for the molecular dynamics (MD) simulation in explicit water solvent. AMBER 14 force field was employed for each set of duplex during the 200ns production-dynamics simulation in orthogonal-box-water solvent by the Particle-Mesh-Ewald (PME) method in infinite periodic boundary conditions (PBC) to determine conformational parameters of the complex. The force-field parameters of modified base-pair were calculated by Gaussian-code using Hartree-Fock /ab-initio methodology. RMSD Results reveal that the conformation of the duplex is sequence dependent and the binding energy of the complex depends on the position of the modified base-pair in the nucleic acid strand. We found that non-bonding energy had a significant contribution to stabilising such type of duplex in comparison to electrostatic energy. The distortion produced within strands by such type of base-pair was local and destabilised the duplex integrity near to substitution, moreover the binding energy of duplex depends on the position of substitution of hydrophobic base-pair and the DNA sequence and strongly supports the corresponding experimental study.

Anyonic order parameters for discrete gauge theories on the lattice

International Nuclear Information System (INIS)

Bais, F.A.; Romers, J.C.

2009-01-01

We present a new family of gauge invariant non-local order parameters Δ α A for (non-abelian) discrete gauge theories on a Euclidean lattice, which are in one-to-one correspondence with the excitation spectrum that follows from the representation theory of the quantum double D(H) of the finite group H. These combine magnetic flux-sector labeled by a conjugacy class with an electric representation of the centralizer subgroup that commutes with the flux. In particular, cases like the trivial class for magnetic flux, or the trivial irrep for electric charge, these order parameters reduce to the familiar Wilson and the 't Hooft operators, respectively. It is pointed out that these novel operators are crucial for probing the phase structure of a class of discrete lattice models we define, using Monte Carlo simulations.

Analysis of deuterium relaxation-derived methyl axis order parameters and correlation with local structure

International Nuclear Information System (INIS)

Mittermaier, Anthony; Kay, Lewis E.; Forman-Kay, Julie D.

1999-01-01

Methyl axis (S2axis) and backbone NH (S2NH) order parameters derived from eight proteins have been analyzed. Similar distribution profiles for Ala S2axis and S2NH order parameters were observed. A good correlation between the two S2axis values of Val and Leu methyl groups is noted, although differences between order parameters can arise. The relation of S2axis or S2NH to solvent accessibility and packing density has also been investigated. Correlations are weak, likely reflecting the importance of collective, non-local motions in proteins. The lack of correlation between these simple structural parameters and dynamics emphasizes the importance of motional studies to fully characterize proteins

Assessing first-order emulator inference for physical parameters in nonlinear mechanistic models

Science.gov (United States)

Hooten, Mevin B.; Leeds, William B.; Fiechter, Jerome; Wikle, Christopher K.

2011-01-01

We present an approach for estimating physical parameters in nonlinear models that relies on an approximation to the mechanistic model itself for computational efficiency. The proposed methodology is validated and applied in two different modeling scenarios: (a) Simulation and (b) lower trophic level ocean ecosystem model. The approach we develop relies on the ability to predict right singular vectors (resulting from a decomposition of computer model experimental output) based on the computer model input and an experimental set of parameters. Critically, we model the right singular vectors in terms of the model parameters via a nonlinear statistical model. Specifically, we focus our attention on first-order models of these right singular vectors rather than the second-order (covariance) structure.

Diffusionless phase transition with two order parameters in spin-crossover solids

Energy Technology Data Exchange (ETDEWEB)

Gudyma, Iurii, E-mail: yugudyma@gmail.com; Ivashko, Victor [Department of General Physics, Chernivtsi National University, 58012 Chernivtsi (Ukraine); Linares, Jorge [Groupe d' Etude de la Matière Condensée (GEMAC), UMR 8635, CNRS, Université de Versailles Saint Quentin, 45 avenue des Etats-Unis, 78035 Versailles (France)

2014-11-07

The quantitative analysis of the interface boundary motion between high-spin and low-spin phases is presented. The nonlinear effect of the switching front rate on the temperature is shown. A compressible model of spin-crossover solid is studied in the framework of the Ising-like model with two-order parameters under statistical approach, where the effect of elastic strain on interaction integral is considered. These considerations led to examination of the relation between the order parameters during temperature changes. Starting from the phenomenological Hamiltonian, entropy has been derived using the mean field approach. Finally, the phase diagram, which characterizes the system, is numerically analyzed.

Hot HB Stars in Globular Clusters - Physical Parameters and Consequences for Theory. VI. The Second Parameter Pair M3 and M13

Science.gov (United States)

Moehler, S.; Landsman, W. B.; Sweigart, A. V.; Grundahl, F.

2002-01-01

We present the results of spectroscopic analyses of hot horizontal branch (HB) stars in M13 and M3, which form a famous second parameter pair. From the spectra we derived - for the first time in M13 - atmospheric parameters (effective temperature and surface gravity) as well as abundances of helium, magnesium, and iron. Consistent with analyses of hot HB stars in other globular clusters we find evidence for helium depletion and iron enrichment in stars hotter than about 12,000 K in both M3 and M13. Accounting for the iron enrichment substantially improves the agreement with canonical evolutionary models, although the derived gravities and masses are still somewhat too low. This remaining discrepancy may be an indication that scaled-solar metal-rich model atmospheres do not adequately represent the highly non-solar abundance ratios found in blue HB stars with radiative levitation. We discuss the effects of an enhancement in the envelope helium abundance on the atmospheric parameters of the blue HB stars, as might be caused by deep mixing on the red giant branch or primordial pollution from an earlier generation of intermediate mass asymptotic giant branch stars.

Hot HB Stars in Globular Clusters: Physical Parameters and Consequences for Theory. VI; The Second Parameter Pair M 3 and M 13

Science.gov (United States)

Moehler, S.; Landsman, W. B.; Sweigart, A. V.; Grundahl, F.

2003-01-01

We present the results of spectroscopic analyses of hot horizontal branch (HB) stars in M 13 and M 3, which form a famous "second parameter" pair. F rom the spectra and Stromgren photometry we derived - for the first time in M 13 - atmospheric parameters (effective temperature and surface gravity). For stars with Stromgren temperatures between 10,000 and 12,000 K we found excellent agreement between the atmospheric parameters derived from Stromgren photometry and those derived from Balmer line profile fits. However, for cooler stars there is a disagreement in the parameters derived by the two methods, for which we have no satisfactory explanation. Stars hotter than 12,000 K show evidence for helium depletion and iron enrichment, both in M 3 and M 13. Accounting for the iron enrichment substantially improves the agreement with canonical evolutionary models, although the derived gravities and masses are still somewhat too low. This remaining discrepancy may be an indication that scaled-solar metal-rich model atmospheres do not adequately represent the highly non-solar abundance ratios found in blue HB stars affected by diffusion. We discuss the effects of an enhancement in the envelope helium abundance on the atmospheric parameters of the blue HB stars, as might be caused by deep mixing on the red giant branch or primordial pollution from an earlier generation of intermediate mass asymptotic giant branch stars. Key words. Stars: atmospheres - Stars: evolution - Stars: horizontal branch - Globular clusters: individual: M 3 - Globular clusters: individual: M 13

Linear Parameter Varying Versus Linear Time Invariant Reduced Order Controller Design of Turboprop Aircraft Dynamics

Directory of Open Access Journals (Sweden)

Widowati

2012-07-01

Full Text Available The applicability of parameter varying reduced order controllers to aircraft model is proposed. The generalization of the balanced singular perturbation method of linear time invariant (LTI system is used to reduce the order of linear parameter varying (LPV system. Based on the reduced order model the low-order LPV controller is designed by using synthesis technique. The performance of the reduced order controller is examined by applying it to lateral-directional control of aircraft model having 20th order. Furthermore, the time responses of the closed loop system with reduced order LPV controllers and reduced order LTI controller is compared. From the simulation results, the 8th order LPV controller can maintain stability and to provide the same level of closed-loop systems performance as the full-order LPV controller. It is different with the reduced-order LTI controller that cannot maintain stability and performance for all allowable parameter trajectories.

Assessing the Interplay between the Physicochemical Parameters of Ion-Pairing Reagents and the Analyte Sequence on the Electrospray Desorption Process for Oligonucleotides

Science.gov (United States)

Basiri, Babak; Murph, Mandi M.; Bartlett, Michael G.

2017-08-01

Alkylamines are widely used as ion-pairing agents during LC-MS of oligonucleotides. In addition to a better chromatographic separation, they also assist with the desorption of oligonucleotide ions into the gas phase, cause charge state reduction, and decrease cation adduction. However, the choice of such ion-pairing agents has considerable influence on the MS signal intensity of oligonucleotides as they can also cause significant ion suppression. Interestingly, optimal ion-pairing agents should be selected on a case by case basis as their choice is strongly influenced by the sequence of the oligonucleotide under investigation. Despite imposing major practical difficulties to analytical method development, such a highly variable system that responds very strongly to the nuances of the electrospray composition provides an excellent opportunity for a fundamental study of the electrospray ionization process. Our investigations using this system quantitatively revealed the major factors that influenced the ESI ionization efficiency of oligonucleotides. Parameters such as boiling point, proton affinity, partition coefficient, water solubility, and Henry's law constants for the ion-pairing reagents and the hydrophobic thymine content of the oligonucleotides were found to be the most significant contributors. Identification of these parameters also allowed for the development of a statistical predictive algorithm that can assist with the choice of an optimum IP agent for each particular oligonucleotide sequence. We believe that research in the field of oligonucleotide bioanalysis will significantly benefit from this algorithm (included in Supplementary Material) as it advocates for the use of lesser-known but more suitable ion-pair alternatives to TEA for many oligonucleotide sequences.

Plasmon-phonon pairing mechanism and superconducting state parameters in layered mercury cuprates

International Nuclear Information System (INIS)

Varshney, D.; Tosi, M.P.

1999-06-01

An effective two-dimensional dynamic interaction is developed which incorporated screening of holes by plasmons and by optical phonons to discuss the nature of the pairing mechanism leading to superconductivity in layered mercury cuprates. The system is treated as an ionic solid containing layers of charge carriers and a model dielectric function is set up which fulfils the appropriate sum rules on the electronic and ionic polarizabilities. The values of the coupling strength and of the Coulomb interaction parameter indicate that the superconductor is in the strong coupling regime with effective screening of the charge carriers. The superconducting transition temperature of optically doped HgBa 2 CuO 4+δ is estimated as 94 K from Kresin's strong coupling theory and the energy gap ratio is substantially larger than the BCS value. The value of the isotope exponent is severely reduced below the BCS value. The implications of the model and its analysis are discussed. (author)

Magnetic anisotropy and order parameter in nanostructured CoPt particles

Science.gov (United States)

Komogortsev, S. V.; Iskhakov, R. S.; Zimin, A. A.; Filatov, E. Yu.; Korenev, S. V.; Shubin, Yu. V.; Chizhik, N. A.; Yurkin, G. Yu.; Eremin, E. V.

2013-10-01

The correlation of magnetic anisotropy energy with order parameter in the crystallites of CoPt nanostructured particles prepared by thermal decomposition and further annealing has been studied by investigation of the approach magnetization to saturation curves and x-ray powder diffraction pattern profiles. It is shown that magnetic anisotropy energy value in partially ordered CoPt crystallite could be described as an intermediate case between two extremes, corresponding to either single or several c-domains of L10 phase in crystallite.

Pair- ${v}$ -SVR: A Novel and Efficient Pairing nu-Support Vector Regression Algorithm.

Science.gov (United States)

Hao, Pei-Yi

This paper proposes a novel and efficient pairing nu-support vector regression (pair--SVR) algorithm that combines successfully the superior advantages of twin support vector regression (TSVR) and classical -SVR algorithms. In spirit of TSVR, the proposed pair--SVR solves two quadratic programming problems (QPPs) of smaller size rather than a single larger QPP, and thus has faster learning speed than classical -SVR. The significant advantage of our pair--SVR over TSVR is the improvement in the prediction speed and generalization ability by introducing the concepts of the insensitive zone and the regularization term that embodies the essence of statistical learning theory. Moreover, pair--SVR has additional advantage of using parameter for controlling the bounds on fractions of SVs and errors. Furthermore, the upper bound and lower bound functions of the regression model estimated by pair--SVR capture well the characteristics of data distributions, thus facilitating automatic estimation of the conditional mean and predictive variance simultaneously. This may be useful in many cases, especially when the noise is heteroscedastic and depends strongly on the input values. The experimental results validate the superiority of our pair--SVR in both training/prediction speed and generalization ability.This paper proposes a novel and efficient pairing nu-support vector regression (pair--SVR) algorithm that combines successfully the superior advantages of twin support vector regression (TSVR) and classical -SVR algorithms. In spirit of TSVR, the proposed pair--SVR solves two quadratic programming problems (QPPs) of smaller size rather than a single larger QPP, and thus has faster learning speed than classical -SVR. The significant advantage of our pair--SVR over TSVR is the improvement in the prediction speed and generalization ability by introducing the concepts of the insensitive zone and the regularization term that embodies the essence of statistical learning theory

The high temperature superconductor YBa2Cu3O7-δ: symmetry of the order parameter, and gradiometers for biomagnetic applications

International Nuclear Information System (INIS)

Kouznetsov, Konstantin A.

1999-01-01

The cuprate YBa 2 Cu 3 O 7-δ is the material that drives the majority of the technological applications of high transition temperature (Tc) superconductors, particularly in the area of superconducting electronics. Despite the widespread use of high-Tc superconducting materials in a variety of applications, the nature of the superconducting state in these materials remains unknown since their discovery more than a decade ago. Many properties of the high-Tc superconductors are determined by their order parameter, which is a wavefunction describing the superconducting condensate. The symmetry of the order parameter in cuprates has been the subject of intensive investigation, leading to conflicting sets of results. Some experiments supported conventional, s-wave symmetry of the order parameter, while others indicated an unconventional, d-wave symmetry. The first part of this thesis is an experimental study of the symmetry of the order parameter in YBa 2 Cu 3 O 7-δ . A new class of phase sensitive experiments is described that involve Josephson tunneling along the c-axis of twinned crystals of YBa 2 Cu 3 O 7-δ . These experiments showed that an s-wave component must reverse sign across the twin boundary, providing direct evidence for a mixed, s+d symmetry of the order parameter in YBa 2 Cu 3 O 7-δ , and thereby reconciling two conflicting sets of previous findings and establishing the dominant d-wave pairing symmetry. The second part of the thesis focuses on practical applications of YBa 2 Cu 3 O 7-δ in superconducting electronics. The authors introduce a novel Superconducting Quantum Interference Device (SQUID) gradiometer. The principle of operation of these long baseline high-T c SQUID gradiometers is based on the inductive coupling of the input coil of a planar flux transformer to the pickup up loop of a directly coupled magnetometer. The long baseline of the gradiometer, 48 mm, and the intrinsic. Balance of better than 1 part in 100 make it an ideal candidate

Pair creation at large inherent angles

International Nuclear Information System (INIS)

Chen, P.; Tauchi, T.; Schroeder, D.V.

1992-01-01

In the next-generation linear colliders, the low-energy e + e - pairs created during the collision of high-energy e + e - beams would cause potential deleterious background problems to the detectors. At low collider energies, the pairs are made essentially by the incoherent process, where the pair is created by the interaction of beamstrahlung photons on the individual particles in the oncoming beam. This problem was first identified by Zolotarev, et al. At energies where the beamstrahlung parameter Υ lies approximately in the range 0.6 approx-lt Υ approx-lt 100, pair creation from the beamstrahlung photons is dominated by a coherent process, first noted by Chen. The seriousness of this pair creation problem lies in the transverse momenta that the pair particles carry when leaving the interaction point (IP) with large angles. Since the central issue is the transverse momentum for particles with large angles, the authors notice that there is another source for it. Namely, when the pair particles are created at low energies, the intrinsic angles of these pairs when produced may already be large. In this paper they reinvestigate the problem, following essentially the same equivalent photon approach, but with changes in specific details including the virtual photon spectrum. In addition, various assumptions are made more explicit. The formulas derived are then applied to the collider parameters designed by Palmer

Pairing theory of high and low temperature superconductors

International Nuclear Information System (INIS)

Nam, Sang Boo

1997-01-01

A scenario which can account for all observed features of both high-Tc superconductors (HTS) and low-Tc superconductors (LTS) is discussed. This scenario is based on the fact that a finite pairing interaction energy range Td is required to have a finite value of Tc and that not all carriers participate in pairings, yielding multiconnected superconductors (MS). A new density of states, derived by keeping the order parameter zero outside of Td, is shown to account for the observed low energy states in HTS and for the temperature dependences in the specific heat, the penetration depth, the optical conductivity, and the tunneling conductance data. I argue that the notion of MS can account for the tunneling data along the a(or b)-, ab-, and c-axis, and the 1/2 flux quantum observed in HTS. The region occupied by unpaired carriers can be considered as a vortex with a fluxoid quantum number equal to 1 (VF), 0 (VZF), or -1 (VAF) when the magnetic flux around the vortex is greater than, equal to, or less than the effective flux produced by the supercurrent, respectively. The Hall anomaly depends on the relative strengths of the contributions via VF and VAF. The fact that the present scenario can account for all observed features of HTS and LTS suggests that the symmetry of the order parameter in HTS may not be different from one in LTS. (author)

Influence of the cylindrical gear pairs parameters to the transverse contact ratio

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Predrag S. Dobratić

2014-06-01

Full Text Available In the field of transmission and power transformation from the power engine to the working machine, gear pairs, are mostly used in mechanical engineering due to their compactness of the structure, high reliability and capacity. One way of improving the performance characteristics of gear pairs, and thus the gear transmitters, is to increase the number of simultaneously meshed pairs of teeth, or increasing the transverse contact ratio. To this end, this paper analyzes in detail the partial and simultaneous influence of the number of teeth and tooth profile shapes, moving through shifting coefficient and pressure angle, to the number of simultaneously meshed pairs of teeth. The obtained results allow us to define the optimum parameters of cylindrical gear pairs, in terms of the size of the transverse contact ratio. Introduction The kinematic indicator of the existence of the transmitting continuity of a rotary movement is the total contact ratio. In order to achieve the transmitting continuity of a rotary movement, the total contact ratio must be higher than one. Based on the total contact ratio, the information on the number of simultaneously meshed pairs of the teeth which rotate during the contact period is obtained. For example, if the  – one and two pairs of teeth alternately take turn, and if the  – two and three pairs of teeth alternately take turn, etc. It should be noted that the  is a necessary but not sufficient condition for achieving multiple meshes. The next condition to meet is the compatibility between the accuracy of teeth production, the teeth rigidity and the intensity of the total load of the teeth pair. The influence of the addendum coefficient on the transverse contact ratio is shown in the paper (Li, 2008. It is shown that changes in the addendum coefficient in conjunction with the corresponding values of the shifting coefficient and gear ratio can achieve the transverse contact ratio value higher than four. The paper

Fully differential Higgs boson pair production in association with a Z boson at next-to-next-to-leading order in QCD

Science.gov (United States)

Li, Hai Tao; Li, Chong Sheng; Wang, Jian

2018-04-01

We present a fully differential next-to-next-to-leading order QCD calculation of the Higgs pair production in association with a Z boson at hadron colliders, which is important for probing the trilinear Higgs self-coupling. The next-to-next-to-leading-order corrections enhance the next-to-leading order total cross sections by a factor of 1.2-1.5, depending on the collider energy, and change the shape of next-to-leading order kinematic distributions. We discuss how to determine the trilinear Higgs self-coupling using our results.

Two-order parameters theory of the metal-insulator phase transition kinetics in the magnetic field

Science.gov (United States)

Dubovskii, L. B.

2018-05-01

The metal-insulator phase transition is considered within the framework of the Ginzburg-Landau approach for the phase transition described with two coupled order parameters. One of the order parameters is the mass density which variation is responsible for the origin of nonzero overlapping of the two different electron bands and the appearance of free electron carriers. This transition is assumed to be a first-order phase one. The free electron carriers are described with the vector-function representing the second-order parameter responsible for the continuous phase transition. This order parameter determines mostly the physical properties of the metal-insulator transition and leads to a singularity of the surface tension at the metal-insulator interface. The magnetic field is involved into the consideration of the system. The magnetic field leads to new singularities of the surface tension at the metal-insulator interface and results in a drastic variation of the phase transition kinetics. A strong singularity in the surface tension results from the Landau diamagnetism and determines anomalous features of the metal-insulator transition kinetics.

Unexpected behavior of an order parameter for lattice gauge theories with matter fields

International Nuclear Information System (INIS)

Meyer, H.

1983-07-01

I consider a slightly modified definition of an order parameter that was recently suggested by DeTar and McLerran. It is supposed to test for confinement in lattice gauge theories when arbitrary matter fields are present, at finite physical temperature β -1 > 0. Its definition is quite directly related to confinement in the sense that no physical states with fractional baryon number can be observed. We test the parameter for different ranges of the coupling constants in the Z(2) Higgs model, whose phase structure is well known at zero temperature. It is found that the order parameter always shows the behavior characteristic of confinement, for all values of the coupling constants and arbitrary nonzero temperature. (orig.)

Microscopic analysis of order parameters in nuclear quantum phase transitions

International Nuclear Information System (INIS)

Li, Z. P.; Niksic, T.; Vretenar, D.; Meng, J.

2009-01-01

Microscopic signatures of nuclear ground-state shape phase transitions in Nd isotopes are studied using excitation spectra and collective wave functions obtained by diagonalization of a five-dimensional Hamiltonian for quadrupole vibrational and rotational degrees of freedom, with parameters determined by constrained self-consistent relativistic mean-field calculations for triaxial shapes. As a function of the physical control parameter, the number of nucleons, energy gaps between the ground state and the excited vibrational states with zero angular momentum, isomer shifts, and monopole transition strengths exhibit sharp discontinuities at neutron number N=90, which is characteristic of a first-order quantum phase transition.

Order-parameter tensor description of HPr in a medium of oriented bicelles.

Science.gov (United States)

van Lune, Franciska; Manning, Linda; Dijkstra, Klaas; Berendsen, Herman J C; Scheek, Ruud M

2002-07-01

Residual dipolar couplings between 15N and 1H nuclear spins in HPr were used to determine the protein's orientation in a medium of bicelles, oriented by a magnetic field. In the case of wild-type HPr the protein's non-spherical shape can explain its orientation in this medium. In the case of the F48W mutant it was found that at least one other mechanism contributes to the observed orientation of the protein, to a degree that depends on the concentration of phosphate ions in the medium. We propose that the F48W mutant has a weak affinity towards the bicelle-surfaces that decreases with increasing phosphate concentrations. We used an order-parameter description to analyse this situation and to determine the axis of main order and the sign of the order parameter pertaining to this additional orientation mechanism.

Effect of a pseudogap on Tc and on the superconducting order parameter

International Nuclear Information System (INIS)

Rodriguez Nunez, J.J.; Reimer Romero, J.J.; Valera, M.; Schmidt, A.A.

2007-09-01

We further develop the pseudogap model proposed by J.L. Tallon and J.W. Loram, Physica C 349, 53-68 (2001). For the pseudogap order parameter we choose a particular form which reproduces the main features of the high temperature superconductor (HTSC) phase diagram which depends on carrier number, n. For fitting the key features of the cuprate oxides we have sensible parameters at our disposal, namely, α, which fixes the density where the pseudogap order parameter is maximum, α' which allows us to display the T c vs n curve and E go which gives us the value of the pseudogap. We have reproduced in a qualitative fashion the main details of the experimental data given in the work of Suryadijaya, T. Sasaqawa, and H. Takagi, Physica C 426-431, 402-406 (2005). Our main results are the following: To have decreased the value of T c with respect to the 'free' case, namely, E go = 0, namely, when the pseudogap order parameter is not present. To have obtained the maximum of T c by choosing α' ≠ 0. To have chosen the minimum value of T c inside the pseudogap region, namely, in the region where the pseudogap parameter is a maximum. To have bounded the region of the superconducting dome by choosing the value of E g. In short, we have proposed a phenomenological form for the pseudogap energy, which depends on carrier number and which reproduces in a qualitative way the results of Suryadijaya, T. Sasaqawa and H. Takagi, Physica C 426-431, 402-406 (2005). Consequently, we conclude that the pseudogap is necessary for HTSC. (author)

Soft radiation in heavy-particle pair production: All-order colour structure and two-loop anomalous dimension

International Nuclear Information System (INIS)

Beneke, M.; Falgari, P.; Schwinn, C.

2010-01-01

We consider the total production cross section of heavy coloured particle pairs in hadronic collisions at the production threshold. We construct a basis in colour space that diagonalizes to all orders in perturbation theory the soft function, which appears in a new factorization formula for the combined resummation of soft gluon and Coulomb gluon effects. This extends recent results on the structure of soft anomalous dimensions and allows us to determine an analytic expression for the two-loop soft anomalous dimension at threshold for all production processes of interest.

Strong pairing approximation in comparison with the exact solutions to the pairing Hamiltonian

Directory of Open Access Journals (Sweden)

Lunyov A.V.

2016-01-01

Full Text Available Results of the Strong Pairing Approximation (SPA as a method with the exact particle number conservation are compared with those of the quasiparticle method (QM. It is shown that SPA comes to the same equations as QM for the gap parameter, chemical potential and one- and two-quasiparticle states. Calculations are performed for 14864Gd84 as an example, and compared with the exact solutions to the pairing Hamiltonian.

Order parameter in CeCu{sub 2}Si{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Vieyra, Hugo A.; Brando, Manuel; Oeschler, Niels; Seiro, Silvia; Geibel, Christoph; Steglich, Frank [Max-Planck-Institute for Chemical Physics of Solids, Dresden (Germany); Jeevan, Hirale S. [I. Physikalisches Institut, Georg-August-Universitaet Goettingen (Germany); Parker, David [US Naval Research Laboratory, Washington, DC (United States)

2011-07-01

Understanding the interplay between magnetism and unconventional superconductivity remains a key challenge in solid-state physics. A clear example is the archetypical heavy-fermion compound CeCu{sub 2}Si{sub 2} which exhibits superconductivity (T{sub c}=600 mK) in the vicinity of a magnetic quantum critical point. It is believed that magnetic fluctuations mediate superconductivity and its order parameter possesses d-wave symmetry, both ideas still under debate. In this work, a high-quality single crystal with a purely superconducting ground state (S type) has been chosen to investigate the low-temperature thermal- and electric-transport characteristics of the superconducting state. Non-vanishing contributions of low-energy quasiparticle excitations to the thermal transport ({kappa}{sub 0}/T>0) suggest the presence of nodal structure in CeCu{sub 2}Si{sub 2}. In turn, angle-dependent resistivity measurements of the upper critical field H{sub c2} point towards unconventional superconductivity with d-wave symmetry of the order parameter. Theoretical calculations reveal the strong influence of Pauli paramagnetic effects and a d{sub xy} symmetry of the gap function.

Observations of multiple order parameters in 5f electron systems

International Nuclear Information System (INIS)

Blackburn, E.

2005-12-01

In this thesis, multiple order parameters originating in the same electronic system are studied. The multi-k magnetic structures, where more than one propagation wavevector, k, is observed in the same volume, are considered as prototypical models. The effect of this structure on the elastic and inelastic response is studied. In cubic 3-k uranium rock-salts, unexpected elastic diffraction events were observed at positions in reciprocal space where the structure factor should have been zero. These diffraction peaks are identified with correlations between the (orthogonal) magnetic order parameters. The 3-k structure also affects the observed dynamics; the spin-wave fluctuations in uranium dioxide as observed by inelastic neutron polarization analysis can only be explained on the basis of a 3-k structure. In the antiferromagnetic superconductor UPd 2 Al 3 the magnetic order and the super-conducting state coexist, and are apparently generated by the same heavy fermions. The effect of an external magnetic field on both the normal and superconducting states is examined. In the normal state, the compound displays Fermi-liquid-like behaviour. The inelastic neutron response is strongly renormalized on entering the superconducting state, and high-precision measurements of the low-energy transfer part of this response confirm that the superconducting energy gap has the same symmetry as the antiferromagnetic lattice. (author)

Direct test of the Gaussian auxiliary field ansatz in nonconserved order parameter phase ordering dynamics

Science.gov (United States)

Yeung, Chuck

2018-06-01

The assumption that the local order parameter is related to an underlying spatially smooth auxiliary field, u (r ⃗,t ) , is a common feature in theoretical approaches to non-conserved order parameter phase separation dynamics. In particular, the ansatz that u (r ⃗,t ) is a Gaussian random field leads to predictions for the decay of the autocorrelation function which are consistent with observations, but distinct from predictions using alternative theoretical approaches. In this paper, the auxiliary field is obtained directly from simulations of the time-dependent Ginzburg-Landau equation in two and three dimensions. The results show that u (r ⃗,t ) is equivalent to the distance to the nearest interface. In two dimensions, the probability distribution, P (u ) , is well approximated as Gaussian except for small values of u /L (t ) , where L (t ) is the characteristic length-scale of the patterns. The behavior of P (u ) in three dimensions is more complicated; the non-Gaussian region for small u /L (t ) is much larger than that in two dimensions but the tails of P (u ) begin to approach a Gaussian form at intermediate times. However, at later times, the tails of the probability distribution appear to decay faster than a Gaussian distribution.

First Measurements of Higher Order Optics Parameters in the LHC

CERN Document Server

Vanbavinckhove, G; Bartolini, R; Calaga, R; Giovannozzi, M; Maclean, E H; Miyamoto, R; Schmidt, F; Tomas, R

2011-01-01

Higher order effects can play an important role in the performance of the LHC. Lack of knowledge of these pa- rameters can increase the tune footprint and compromise the beam lifetime. First measurements of these parameters at injection and flattop have been conducted. Detailed sim- ulations are compared to the measurements together with discussions on the measurement limitations.

Gluino-pair production at the Tevatron

International Nuclear Information System (INIS)

Beenakker, W.; Spira, M.; Zerwas, P.M.

1995-05-01

The next-to-leading order QCD corrections to the production of gluino pairs at the Tevatron are presented in this paper. Similar to the production of squark-antisquark pairs, the dependence of the cross section on the renormalization/factorization scale is reduced considerably by including the higher-order corrections. The cross section increases with respect to the lowest-order calculation which, in previous experimental analyses, had been evaluated at the scale of the invariant energy of the partonic subprocesses. (orig.)

Thermodynamics of pairing phase transition in nuclei

International Nuclear Information System (INIS)

Karim, Afaque; Ahmad, Shakeb

2014-01-01

The pairing gaps, pairing energy, heat capacity and entropy are calculated within BCS (Bardeen- Cooper-Schrieffer) based quasi particle approach, including thermal fluctuations on pairing field within pairing model for all nuclei (light, medium, heavy and super heavy nuclei). Quasi particles approach in BCS theory was introduced and reformulated to study various properties. For thermodynamic behavior of nuclei at finite temperatures, the anomalous averages of creation and annihilation operators are introduced. It is solved self consistently at finite temperatures to obtain BCS Hamiltonian. After doing unitary transformation, we obtained the Hamiltonian in the diagonal form. Thus, one gets temperature dependence gap parameter and pairing energy for nuclei. Moreover, the energy at finite temperatures is the sum of the condensation energy and the thermal energy of fermionic quasi particles. With the help of BCS Hamiltonian, specific heat, entropy and free energy are calculated for different nuclei. In this paper the gap parameter occupation number and pairing energy as a function of temperature which is important for all the light, medium, heavy and super heavy nuclei is calculated. Moreover, the various thermo dynamical quantities like specific heat, entropy and free energy is also obtained for different nuclei. Thus, the thermodynamics of pairing phase transition in nuclei is studied

Collective neutrino-pair emission due to Cooper pairing of protons in superconducting neutron stars

International Nuclear Information System (INIS)

Leinson, L.B.

2001-01-01

The neutrino emission due to formation and breaking of Cooper pairs of protons in superconducting cores of neutron stars is considered with taking into account the electromagnetic coupling of protons to ambient electrons. It is shown that collective response of electrons to the proton quantum transition contributes coherently to the complete interaction with a neutrino field and enhances the neutrino-pair production. Our calculation shows that the contribution of the vector weak current to the ννbar emissivity of protons is much larger than that calculated by different authors without taking into account the plasma effects. Partial contribution of the pairing protons to the total neutrino radiation from the neutron star core is very sensitive to the critical temperatures for the proton and neutron pairing. We show domains of these parameters where the neutrino radiation, caused by a singlet-state pairing of protons is dominating

The paired-domination and the upper paired-domination numbers of graphs

Directory of Open Access Journals (Sweden)

Włodzimierz Ulatowski

2015-01-01

Full Text Available In this paper we continue the study of paired-domination in graphs. A paired-dominating set, abbreviated PDS, of a graph \\(G\\ with no isolated vertex is a dominating set of vertices whose induced subgraph has a perfect matching. The paired-domination number of \\(G\\, denoted by \\(\\gamma_{p}(G\\, is the minimum cardinality of a PDS of \\(G\\. The upper paired-domination number of \\(G\\, denoted by \\(\\Gamma_{p}(G\\, is the maximum cardinality of a minimal PDS of \\(G\\. Let \\(G\\ be a connected graph of order \\(n\\geq 3\\. Haynes and Slater in [Paired-domination in graphs, Networks 32 (1998, 199-206], showed that \\(\\gamma_{p}(G\\leq n-1\\ and they determine the extremal graphs \\(G\\ achieving this bound. In this paper we obtain analogous results for \\(\\Gamma_{p}(G\\. Dorbec, Henning and McCoy in [Upper total domination versus upper paired-domination, Questiones Mathematicae 30 (2007, 1-12] determine \\(\\Gamma_{p}(P_n\\, instead in this paper we determine \\(\\Gamma_{p}(C_n\\. Moreover, we describe some families of graphs \\(G\\ for which the equality \\(\\gamma_{p}(G=\\Gamma_{p}(G\\ holds.

Pairing mechanism in Bi-O superconductors: A finite-size chain calculation

International Nuclear Information System (INIS)

Aligia, A.A.; Nunez Regueiro, M.D.; Gagliano, E.R.

1989-01-01

We have studied the pairing mechanism in BiO 3 systems by calculating the binding energy of a pair of holes in finite Bi-O chains, for parameters that simulate three-dimensional behavior. In agreement with previous results using perturbation theory in the hopping t, for covalent Bi-O binding and parameters for which the parent compound has a disproportionate ground state, pairing induced by the presence of biexcitons is obtained for sufficiently large interatomic Coulomb repulsion. The analysis of appropriate correlation functions shows a rapid metallization of the system as t and the number of holes increase. This fact shrinks the region of parameters for which the finite-size calculations can be trusted without further study. The same model for other parameters yields pairing in two other regimes: bipolaronic and magnetic excitonic

Treatment of pairing correlations based on the equations of motion for zero-coupled pair operators

International Nuclear Information System (INIS)

Andreozzi, F.; Covello, A.; Gargano, A.; Ye, L.J.; Porrino, A.

1985-01-01

The pairing problem is treated by means of the equations of motion for zero-coupled pair operators. Exact equations for the seniority-v states of N particles are derived. These equations can be solved by a step-by-step procedure which consists of progressively adding pairs of particles to a core. The theory can be applied at several levels of approximation depending on the number of core states which are taken into account. Some numerical applications to the treatment of v = 0, v = 1, and v = 2 states in the Ni isotopes are performed. The accuracy of various approximations is tested by comparison with exact results. For the seniority-one and seniority-two problems it turns out that the results obtained from the first-order theory are very accurate, while those of higher order calculations are practically exact. Concerning the seniority-zero problem, a fifth-order calculation reproduces quite well the three lowest states

Polarized neutron scattering study of the multiple order parameter system NdB4

Science.gov (United States)

Metoki, N.; Yamauchi, H.; Matsuda, M.; Fernandez-Baca, J. A.; Watanuki, R.; Hagihala, M.

2018-05-01

Neutron polarization analysis has been carried out in order to clarify the magnetic structures of multiple order parameter f -electron system NdB4. We confirmed the noncollinear "all-in all-out" structure (Γ4) of the in-plane moment, which is in good agreement with our previous neutron powder diffraction study. We found that the magnetic moment along the c -axis mc showed diagonally antiferromagnetic structure (Γ10), inconsistent with previously reported "vortex" structure (Γ2). The microscopic mixture of these two structures with q⃗0=(0 ,0 ,0 ) appears in phase II and remains stable in phases III and IV, where an incommensurate modulation coexists. The unusual magnetic ordering is phenomenologically understood via Landau theory with the primary order parameter Γ4 coupled with higher-order secondary order parameter Γ10. The magnetic moments were estimated to be 1.8 ±0.2 and 0.2 ±0.05 μB at T =7.5 K for Γ4 and Γ10, respectively. We also found a long-period incommensurate modulation of the q⃗1=(0 ,0 ,1 /2 ) antiferromagnetic structure of mc with the propagation q⃗s 1=(0.14 ,0.14 ,0.1 ) and q⃗s 2=(0.2 ,0 ,0.1 ) in phase III and IV, respectively. The amplitude of sinusoidal modulation was about mc=1.0 ±0.2 μB at T =1.5 K. The local (0 ,0 ,1 /2 ) structure consists of in-plane ferromagnetic and out-of-plane antiferromagnetic coupling of mc, opposite to the coexisting Γ10. The mc of Γ10 is significantly enhanced up to 0.6 μB at T =1.5 K, which is accompanied by the incommensurate modulations. The Landau phenomenological approach indicates that the higher-order magnetic and/or multipole interactions based on the pseudoquartet f -electron state play important roles.

An unscaled parameter to measure the order of surfaces: a new surface elaboration to increase cells adhesion.

Science.gov (United States)

Bigerelle, M; Anselme, K; Dufresne, E; Hardouin, P; Iost, A

2002-08-01

We present a new parameter to quantify the order of a surface. This parameter is scale-independent and can be used to compare the organization of a surface at different scales of range and amplitude. To test the accuracy of this roughness parameter versus a hundred existing ones, we created an original statistical bootstrap method. In order to assess the physical relevance of this new parameter, we elaborated a great number of surfaces with various roughness amplitudes on titanium and titanium-based alloys using different physical processes. Then we studied the influence of the roughness amplitude on in vitro adhesion and proliferation of human osteoblasts. It was then shown that our new parameter best discriminates among the cell adhesion phenomena than others' parameters (Average roughness (Ra em leader )): cells adhere better on isotropic surfaces with a low order, provided this order is quantified on a scale that is more important than that of the cells. Additionally, on these low ordered metallic surfaces, the shape of the cells presents the same morphological aspect as that we can see on the human bone trabeculae. The method used to prepare these isotropic surfaces (electroerosion) could be undoubtedly and easily applied to prepare most biomaterials with complex geometries and to improve bone implant integration. Moreover, the new order parameter we developed may be particularly useful for the fundamental understanding of the mechanism of bone cell installation on a relief and of the formation of bone cell-material interface.

BAYESIAN PARAMETER ESTIMATION IN A MIXED-ORDER MODEL OF BOD DECAY. (U915590)

Science.gov (United States)

We describe a generalized version of the BOD decay model in which the reaction is allowed to assume an order other than one. This is accomplished by making the exponent on BOD concentration a free parameter to be determined by the data. This "mixed-order" model may be ...

HQET at order 1/m. Pt. 1. Non-perturbative parameters in the quenched approximation

International Nuclear Information System (INIS)

Blossier, Benoit; Della Morte, Michele; Garron, Nicolas; Edinburgh Univ.; Sommer, Rainer

2010-01-01

We determine non-perturbatively the parameters of the lattice HQET Lagrangian and those of heavy-light axial-vector and vector currents in the quenched approximation. The HQET expansion includes terms of order 1/m b . Our results allow to compute, for example, the heavy-light spectrum and B-meson decay constants in the static approximation and to order 1/m b in HQET. The determination of the parameters is separated into universal and non-universal parts. The universal results can be used to determine the parameters for various discretizations. The computation reported in this paper uses the plaquette gauge action and the ''HYP1/2'' action for the b-quark described by HQET. The parameters of the currents also depend on the light-quark action, for which we choose non-perturbatively O(a)-improved Wilson fermions. (orig.)

HQET at order 1/m. Pt. 1. Non-perturbative parameters in the quenched approximation

Energy Technology Data Exchange (ETDEWEB)

Blossier, Benoit [Paris XI Univ., 91 - Orsay (France). Lab. de Physique Theorique; Della Morte, Michele [Mainz Univ. (Germany). Inst. fuer Kernphysik; Garron, Nicolas [Universidad Autonoma de Madrid (Spain). Dept. Fisica Teorica y Inst. de Fisica Teorica UAM/CSIC; Edinburgh Univ. (United Kingdom). School of Physics and Astronomy - SUPA; Sommer, Rainer [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

2010-01-15

We determine non-perturbatively the parameters of the lattice HQET Lagrangian and those of heavy-light axial-vector and vector currents in the quenched approximation. The HQET expansion includes terms of order 1/m{sub b}. Our results allow to compute, for example, the heavy-light spectrum and B-meson decay constants in the static approximation and to order 1/m{sub b} in HQET. The determination of the parameters is separated into universal and non-universal parts. The universal results can be used to determine the parameters for various discretizations. The computation reported in this paper uses the plaquette gauge action and the ''HYP1/2'' action for the b-quark described by HQET. The parameters of the currents also depend on the light-quark action, for which we choose non-perturbatively O(a)-improved Wilson fermions. (orig.)

A family of integrable differential–difference equations, its bi-Hamiltonian structure and binary nonlinearization of the Lax pairs and adjoint Lax pairs

International Nuclear Information System (INIS)

Xu Xixiang

2012-01-01

Highlights: ► We deduce a family of integrable differential–difference equations. ► We present a discrete Hamiltonian operator involving two arbitrary real parameters. ► We establish the bi-Hamiltonian structure for obtained integrable family. ► Liouvolle integrability of the obtained family is demonstrated. ► Every equation in obtained family is factored through the binary nonlinearization. - Abstract: A family of integrable differential–difference equations is derived by the method of Lax pairs. A discrete Hamiltonian operator involving two arbitrary real parameters is introduced. When the parameters are suitably selected, a pair of discrete Hamiltonian operators is presented. Bi-Hamiltonian structure of obtained family is established by discrete trace identity. Then, Liouville integrability for the obtained family is proved. Ultimately, through the binary nonlinearization of the Lax pairs and adjoint Lax pairs, every differential–difference equation in obtained family is factored by an integrable symplectic map and a finite-dimensional integrable system in Liouville sense.

Strong orientational coordinates and orientational order parameters for symmetric objects

International Nuclear Information System (INIS)

Haji-Akbari, Amir; Glotzer, Sharon C

2015-01-01

Recent advancements in the synthesis of anisotropic macromolecules and nanoparticles have spurred an immense interest in theoretical and computational studies of self-assembly. The cornerstone of such studies is the role of shape in self-assembly and in inducing complex order. The problem of identifying different types of order that can emerge in such systems can, however, be challenging. Here, we revisit the problem of quantifying orientational order in systems of building blocks with non-trivial rotational symmetries. We first propose a systematic way of constructing orientational coordinates for such symmetric building blocks. We call the arising tensorial coordinates strong orientational coordinates (SOCs) as they fully and exclusively specify the orientation of a symmetric object. We then use SOCs to describe and quantify local and global orientational order, and spatiotemporal orientational correlations in systems of symmetric building blocks. The SOCs and the orientational order parameters developed in this work are not only useful in performing and analyzing computer simulations of symmetric molecules or particles, but can also be utilized for the efficient storage of rotational information in long trajectories of evolving many-body systems. (paper)

Order parameters in the Landau–de Gennes theory – the static and dynamic scenarios

KAUST Repository

Majumdar, Apala

2011-02-17

We obtain quantitative estimates for the scalar order parameters of liquid crystal configurations in three-dimensional geometries, within the Landau-de Gennes framework. We consider both static equilibria and non-equilibrium dynamics and we include external fields and surface anchoring energies in our formulation. Using maximum principle-type arguments, we obtain explicit bounds for the corresponding scalar order parameters in both static and dynamic situations; these bounds are given in terms of the material-dependent thermotropic coefficients, electric field strength and surface anchoring coefficients. These bounds provide estimates for the degree of orientational ordering, quantify the competing effects of the different energetic contributions and can be used to test the accuracy of numerical simulations. © 2011 Taylor & Francis.

Order parameters in the Landau–de Gennes theory – the static and dynamic scenarios

KAUST Repository

Majumdar, Apala

2011-01-01

We obtain quantitative estimates for the scalar order parameters of liquid crystal configurations in three-dimensional geometries, within the Landau-de Gennes framework. We consider both static equilibria and non-equilibrium dynamics and we include external fields and surface anchoring energies in our formulation. Using maximum principle-type arguments, we obtain explicit bounds for the corresponding scalar order parameters in both static and dynamic situations; these bounds are given in terms of the material-dependent thermotropic coefficients, electric field strength and surface anchoring coefficients. These bounds provide estimates for the degree of orientational ordering, quantify the competing effects of the different energetic contributions and can be used to test the accuracy of numerical simulations. © 2011 Taylor & Francis.

The analysis of photon pair source at telecom wavelength based on the BBO crystal (Conference Presentation)

Science.gov (United States)

Gajewski, Andrzej; Kolenderski, Piotr L.

2016-10-01

There are several problems that must be solved in order to increase the distance of quantum communication protocols based on photons as an information carriers. One of them is the dispersion, whose effects can be minimized by engineering spectral properties of transmitted photons. In particular, it is expected that positively correlated photon pairs can be very useful. We present the full characterization of a source of single photon pairs at a telecom wavelength based on type II spontaneous parametric down conversion (SPDC) process in a beta-barium borate (BBO) crystal. In the type II process, a pump photon, which is polarized extraordinarily, splits in a nonlinear medium into signal and idler photons, which are polarized perpendicularly to each other. In order for the process to be efficient a phase matching condition must be fulfilled. These conditions originate from momentum and energy conservation rules and put severe restrictions on source parameters. Seemingly, these conditions force the photon pair to be negatively correlated in their spectral domain. However, it is possible to achieve positive correlation for pulsed pumping. The experimentally available degrees of freedom of a source are the width of the pumping beam, the collected modes' widths, the length of the nonlinear crystal and the duration of the pumping pulse. In our numerical model we use the following figures of merit: the pair production rate, the efficiency of photon coupling into a single mode fiber, the spectral correlation of the coupled photon pair. The last one is defined as the Pearson correlation parameter for a joint spectral distribution. The aim here is to find the largest positive spectral correlation and the highest coupling efficiency. By resorting to the numerical model Ref. [1] we showed in Ref. [2], that by careful adjustment of the pump's and the collected modes' characteristics, one can optimize any of the source's parameters. Our numerical outcomes conform to the

Magnetic quasi-long-range ordering in nematic systems due to competition between higher-order couplings

Science.gov (United States)

Žukovič, Milan; Kalagov, Georgii

2018-05-01

Critical properties of the two-dimensional X Y model involving solely nematic-like terms of the second and third orders are investigated by spin-wave analysis and Monte Carlo simulation. It is found that, even though neither of the nematic-like terms alone can induce magnetic ordering, their coexistence and competition leads to an extended phase of the magnetic quasi-long-range-order phase, wedged between the two nematic-like phases induced by the respective couplings. Thus, except for the multicritical point, at which all the phases meet, for any finite value of the coupling parameters ratio there are two phase transition: one from the paramagnetic phase to one of the two nematic-like phases followed by another one at lower temperatures to the magnetic phase. The finite-size scaling analysis indicates that the phase transitions between the magnetic and nematic-like phases belong to the Ising and three-state Potts universality classes. Inside the competition-induced algebraic magnetic phase, the spin-pair correlation function is found to decay even much more slowly than in the standard X Y model with purely magnetic interactions. Such a magnetic phase is characterized by an extremely low vortex-antivortex pair density attaining a minimum close to the point at which the two couplings are of about equal strength.

Evaluation of third order nonlinear optical parameters of CdS/PVA nanocomposite

International Nuclear Information System (INIS)

Sharma, Mamta; Tripathi, S. K.

2015-01-01

CdS nanoparticles dispersed in PVA are prepared by Chemical method at room temperature. The nonlinear optical parameters such as nonlinear absorption (β), nonlinear refractive index (n 2 ) and nonlinear susceptibility (χ 3 ) are calculated for this sample by using Z-scan technique. CdS/PVA samples show the two photon absorption mechanism. The third order nonlinear susceptibility is calculated from n 2 and β and is found to be of the order of 10 −7 – 10 −8 m 2 /V 2 . The larger value of third order nonlinear susceptibility is due to dielectric and quantum confinement effect

Simulation of Higher-Order Electrical Circuits with Stochastic Parameters via SDEs

Directory of Open Access Journals (Sweden)

BRANCIK, L.

2013-02-01

Full Text Available The paper deals with a technique for the simulation of higher-order electrical circuits with parameters varying randomly. The principle consists in the utilization of the theory of stochastic differential equations (SDE, namely the vector form of the ordinary SDEs. Random changes of both excitation voltage and some parameters of passive circuit elements are considered, and circuit responses are analyzed. The voltage and/or current responses are computed and represented in the form of the sample means accompanied by their confidence intervals to provide reliable estimates. The method is applied to analyze responses of the circuit models of optional orders, specially those consisting of a cascade connection of the RLGC networks. To develop the model equations the state-variable method is used, afterwards a corresponding vector SDE is formulated and a stochastic Euler numerical method applied. To verify the results the deterministic responses are also computed by the help of the PSpice simulator or the numerical inverse Laplace transforms (NILT procedure in MATLAB, while removing random terms from the circuit model.

On the relationship between NMR-derived amide order parameters and protein backbone entropy changes.

Science.gov (United States)

Sharp, Kim A; O'Brien, Evan; Kasinath, Vignesh; Wand, A Joshua

2015-05-01

Molecular dynamics simulations are used to analyze the relationship between NMR-derived squared generalized order parameters of amide NH groups and backbone entropy. Amide order parameters (O(2) NH ) are largely determined by the secondary structure and average values appear unrelated to the overall flexibility of the protein. However, analysis of the more flexible subset (O(2) NH  entropy than that reported by the side chain methyl axis order parameters, O(2) axis . A calibration curve for backbone entropy vs. O(2) NH is developed, which accounts for both correlations between amide group motions of different residues, and correlations between backbone and side chain motions. This calibration curve can be used with experimental values of O(2) NH changes obtained by NMR relaxation measurements to extract backbone entropy changes, for example, upon ligand binding. In conjunction with our previous calibration for side chain entropy derived from measured O(2) axis values this provides a prescription for determination of the total protein conformational entropy changes from NMR relaxation measurements. © 2015 Wiley Periodicals, Inc.

Structural variability and the nature of intermolecular interactions in Watson-Crick B-DNA base pairs.

Science.gov (United States)

Czyznikowska, Z; Góra, R W; Zaleśny, R; Lipkowski, P; Jarzembska, K N; Dominiak, P M; Leszczynski, J

2010-07-29

A set of nearly 100 crystallographic structures was analyzed using ab initio methods in order to verify the effect of the conformational variability of Watson-Crick guanine-cytosine and adenine-thymine base pairs on the intermolecular interaction energy and its components. Furthermore, for the representative structures, a potential energy scan of the structural parameters describing mutual orientation of the base pairs was carried out. The results were obtained using the hybrid variational-perturbational interaction energy decomposition scheme. The electron correlation effects were estimated by means of the second-order Møller-Plesset perturbation theory and coupled clusters with singles and doubles method adopting AUG-cc-pVDZ basis set. Moreover, the characteristics of hydrogen bonds in complexes, mimicking those appearing in B-DNA, were evaluated using topological analysis of the electron density. Although the first-order electrostatic energy is usually the largest stabilizing component, it is canceled out by the associated exchange repulsion in majority of the studied crystallographic structures. Therefore, the analyzed complexes of the nucleic acid bases appeared to be stabilized mainly by the delocalization component of the intermolecular interaction energy which, in terms of symmetry adapted perturbation theory, encompasses the second- and higher-order induction and exchange-induction terms. Furthermore, it was found that the dispersion contribution, albeit much smaller in terms of magnitude, is also a vital stabilizing factor. It was also revealed that the intermolecular interaction energy and its components are strongly influenced by four (out of six) structural parameters describing mutual orientation of bases in Watson-Crick pairs, namely shear, stagger, stretch, and opening. Finally, as a part of a model study, much of the effort was devoted to an extensive testing of the UBDB databank. It was shown that the databank quite successfully reproduces the

High-order dynamic modeling and parameter identification of structural discontinuities in Timoshenko beams by using reflection coefficients

Science.gov (United States)

Fan, Qiang; Huang, Zhenyu; Zhang, Bing; Chen, Dayue

2013-02-01

Properties of discontinuities, such as bolt joints and cracks in the waveguide structures, are difficult to evaluate by either analytical or numerical methods due to the complexity and uncertainty of the discontinuities. In this paper, the discontinuity in a Timoshenko beam is modeled with high-order parameters and then these parameters are identified by using reflection coefficients at the discontinuity. The high-order model is composed of several one-order sub-models in series and each sub-model consists of inertia, stiffness and damping components in parallel. The order of the discontinuity model is determined based on the characteristics of the reflection coefficient curve and the accuracy requirement of the dynamic modeling. The model parameters are identified through the least-square fitting iteration method, of which the undetermined model parameters are updated in iteration to fit the dynamic reflection coefficient curve with the wave-based one. By using the spectral super-element method (SSEM), simulation cases, including one-order discontinuities on infinite- and finite-beams and a two-order discontinuity on an infinite beam, were employed to evaluate both the accuracy of the discontinuity model and the effectiveness of the identification method. For practical considerations, effects of measurement noise on the discontinuity parameter identification are investigated by adding different levels of noise to the simulated data. The simulation results were then validated by the corresponding experiments. Both the simulation and experimental results show that (1) the one-order discontinuities can be identified accurately with the maximum errors of 6.8% and 8.7%, respectively; (2) and the high-order discontinuities can be identified with the maximum errors of 15.8% and 16.2%, respectively; and (3) the high-order model can predict the complex discontinuity much more accurately than the one-order discontinuity model.

Anti-pairing in learning of a neural network with redundant hidden units

International Nuclear Information System (INIS)

Kwon, Chulan; Kim, Hyong Kyun

2005-01-01

We study the statistical mechanics of learning from examples between the two-layered committee machines with different numbers of hidden units using the replica theory. The number M of hidden units of the student network is larger than the number M T of those of the target network called the teacher. We choose the networks to have binary synaptic weights, ±1, which makes it possible to compare the calculation with the Monte Carlo simulation. We propose an effective teacher as a virtual target network which has the same M hidden units as the student and gives identical outputs with those of the original teacher. This is a way of making a conjecture for a ground state of a thermodynamic system, given by the weights of the effective teacher in our study. We suppose that the weights on M T hidden units of the effective teacher are the same as those of the original teacher while those on M - M T redundant hidden units are composed of anti-pairs, {1, - 1}, with probability 1 - p in the limit p → 0. For p = 0 exact, there are no terms related to the effective teacher in the calculation, for the contributions of anti-pairs to outputs are exactly cancelled. In the limit p → 0, however, we find that the learnt weights of the student are actually equivalent to those of the suggested effective teacher, which is not possible from the calculation for p = 0. p plays the role of a symmetry breaking parameter for anti-pairing ordering, which is analogous to the magnetic field for the Ising model. A first-order phase transition is found to be signalled by breaking of symmetry in permuting hidden units. Above a critical number of examples, the student is shown to learn perfectly the effective teacher. Anti-pairing can be measured by a set of order parameters; zero in the permutation-symmetric phase and nonzero in the permutation symmetry breaking phase. Results from the Monte Carlo simulation are shown to be in good agreement with those from the replica calculation

On the analysis of glow curves with the general order kinetics: Reliability of the computed trap parameters

Energy Technology Data Exchange (ETDEWEB)

Ortega, F. [Facultad de Ingeniería (UNCPBA) and CIFICEN (UNCPBA – CICPBA – CONICET), Av. del Valle 5737, 7400 Olavarría (Argentina); Santiago, M.; Martinez, N.; Marcazzó, J.; Molina, P.; Caselli, E. [Instituto de Física Arroyo Seco (UNCPBA) and CIFICEN (UNCPBA – CICPBA – CONICET), Pinto 399, 7000 Tandil (Argentina)

2017-04-15

Nowadays the most employed kinetics for analyzing glow curves is the general order kinetics (GO) proposed by C. E. May and J. A. Partridge. As shown in many articles this kinetics might yield wrong parameters characterizing trap and recombination centers. In this article this kinetics is compared with the modified general order kinetics put forward by M. S. Rasheedy by analyzing synthetic glow curves. The results show that the modified kinetics gives parameters, which are more accurate than that yield by the original general order kinetics. A criterion is reported to evaluate the accuracy of the trap parameters found by deconvolving glow curves. This criterion was employed to assess the reliability of the trap parameters of the YVO{sub 4}: Eu{sup 3+} compounds.

Inhomogeneous ensembles of radical pairs in chemical compasses

Science.gov (United States)

Procopio, Maria; Ritz, Thorsten

2016-11-01

The biophysical basis for the ability of animals to detect the geomagnetic field and to use it for finding directions remains a mystery of sensory biology. One much debated hypothesis suggests that an ensemble of specialized light-induced radical pair reactions can provide the primary signal for a magnetic compass sensor. The question arises what features of such a radical pair ensemble could be optimized by evolution so as to improve the detection of the direction of weak magnetic fields. Here, we focus on the overlooked aspect of the noise arising from inhomogeneity of copies of biomolecules in a realistic biological environment. Such inhomogeneity leads to variations of the radical pair parameters, thereby deteriorating the signal arising from an ensemble and providing a source of noise. We investigate the effect of variations in hyperfine interactions between different copies of simple radical pairs on the directional response of a compass system. We find that the choice of radical pair parameters greatly influences how strongly the directional response of an ensemble is affected by inhomogeneity.

Faithful One-way Trip Deterministic Secure Quantum Communication Scheme Against Collective Rotating Noise Based on Order Rearrangement of Photon Pairs

Science.gov (United States)

Yuan, Hao; Zhang, Qin; Hong, Liang; Yin, Wen-jie; Xu, Dong

2014-08-01

We present a novel scheme for deterministic secure quantum communication (DSQC) over collective rotating noisy channel. Four special two-qubit states are found can constitute a noise-free subspaces, and so are utilized as quantum information carriers. In this scheme, the information carriers transmite over the quantum channel only one time, which can effectively reduce the influence of other noise existing in quantum channel. The information receiver need only perform two single-photon collective measurements to decode the secret messages, which can make the present scheme more convenient in practical application. It will be showed that our scheme has a relatively high information capacity and intrisic efficiency. Foremostly, the decoy photon pair checking technique and the order rearrangement of photon pairs technique guarantee that the present scheme is unconditionally secure.

Investigate the effect of anisotropic order parameter on the specific heat of anisotropic two-band superconductors

International Nuclear Information System (INIS)

Udomsamuthirun, P.; Peamsuwan, R.; Kumvongsa, C.

2009-01-01

The effect of anisotropic order parameter on the specific heat of anisotropic two-band superconductors in BCS weak-coupling limit is investigated. An analytical specific heat jump and the numerical specific heat are shown by using anisotropic order parameters, and the electron-phonon interaction and non-electron-phonon interaction. The two models of anisotropic order parameters are used for numerical calculation that we find little effect on the numerical results. The specific heat jump of MgB 2 , Lu 2 Fe 3 Si 5 and Nb 3 Sn superconductors can fit well with both of them. By comparing the experimental data with overall range of temperature, the best fit is Nb 3 Sn, MgB 2 , and Lu 2 Fe 3 Si 5 superconductors.

Study of the pair-interaction function in some normal metals; Etude de l'interaction de paire dans quelques metaux normaux

Energy Technology Data Exchange (ETDEWEB)

Pick, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-06-01

The pair interaction function has been derived for the following metals: Li, Na, K, Al. It is obtained via a second order perturbation expansion of the wave functions of the conduction electrons using a self-consistent pseudo-potential. Exchange and correlations between those electrons have been ignored. Such an interaction is only valid at constant volume and depends on a single experimental parameter, namely the ionic volume. Its main features are a pronounced minimum in the vicinity of the nearest neighbours, especially marked in alkaline metals, and an asymptotic decrease of the form cos(2k{sub F}r)/r{sup 3}. This interaction gives the correct crystalline structure of these metals at 0 K as well as a good approximation of the phonon spectrum of an alkaline. The validity of the perturbation technique is discussed. We prove that the pair interaction function is correctly given to second order in the pseudo-potential despite the various approximations and errors involved by such a method. (author) [French] L'interaction de paire effective entre ions a ete calculee dans les metaux Li, Na, K et Al. Elle est obtenue par un developpement en serie de perturbation des fonctions d'onde des electrons de conduction. Le developpement est pousse au deuxieme ordre et utilise un pseudo-potentiel self-consistant. Les phenomenes d'echange et de correlations entre ces electrons ont ete negliges. L'interaction calculee n'a de sens qu'a volume constant. Elle depend d'un seul parametre experimental, le volume ionique. Elle se caracterise par un minimum prononce de l'energie de paire pour les proches voisins, surtout marque chez les alcalins. Elle decroit asymptotiquement en cos(2k{sub F}r)/r{sup 3}. Elle permet de predire la structure cristalline la plus stable a 0 K; elle donne le spectre de phonons des alcalins avec une assez bonne precision. Par ailleurs, la validite de la methode de perturbation du deuxieme ordre est discutee. On montre qu'elle donne correctement l

Evaluation of third order nonlinear optical parameters of CdS/PVA nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Sharma, Mamta [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160014 (India); Department of Applied Sciences (Physics), UIET, Panjab University, Chandigarh-160014 (India); Tripathi, S. K., E-mail: surya@pu.ac.in, E-mail: surya-tr@yahoo.com [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160014 (India)

2015-06-24

CdS nanoparticles dispersed in PVA are prepared by Chemical method at room temperature. The nonlinear optical parameters such as nonlinear absorption (β), nonlinear refractive index (n{sub 2}) and nonlinear susceptibility (χ{sup 3}) are calculated for this sample by using Z-scan technique. CdS/PVA samples show the two photon absorption mechanism. The third order nonlinear susceptibility is calculated from n{sub 2} and β and is found to be of the order of 10{sup −7} – 10{sup −8} m{sup 2}/V{sup 2}. The larger value of third order nonlinear susceptibility is due to dielectric and quantum confinement effect.

Parameter estimation of fractional-order chaotic systems by using quantum parallel particle swarm optimization algorithm.

Directory of Open Access Journals (Sweden)

Yu Huang

Full Text Available Parameter estimation for fractional-order chaotic systems is an important issue in fractional-order chaotic control and synchronization and could be essentially formulated as a multidimensional optimization problem. A novel algorithm called quantum parallel particle swarm optimization (QPPSO is proposed to solve the parameter estimation for fractional-order chaotic systems. The parallel characteristic of quantum computing is used in QPPSO. This characteristic increases the calculation of each generation exponentially. The behavior of particles in quantum space is restrained by the quantum evolution equation, which consists of the current rotation angle, individual optimal quantum rotation angle, and global optimal quantum rotation angle. Numerical simulation based on several typical fractional-order systems and comparisons with some typical existing algorithms show the effectiveness and efficiency of the proposed algorithm.

Next-to-next-to-leading order O(α2α2s) results for top quark pair production in photon-photon collisions. The one-loop squared contribution

International Nuclear Information System (INIS)

Koerner, J.G.

2006-11-01

We calculate the so-called loop-by-loop contributions to the next-to-next-to-leading order O(α 2 α 2 s ) radiative QCD corrections for the production of heavy quark pairs in the collisions of unpolarized on-shell photons. In particular, we present analytical results for the squared matrix elements that correspond to the product of the one-loop amplitudes. All results of the perturbative calculation are given in the dimensional regularization scheme. These results represent the Abelian part of the corresponding gluon-induced next-to-next-to-leading order cross section for heavy quark pair hadroproduction. (orig.)

Relationship of Cord Blood Immunoglobulin E and Maternal Immunoglobulin E with Birth Order and Maternal History of Allergy in Albanian Mother/Neonate Pairs.

Science.gov (United States)

Latifi-Pupovci, Hatixhe; Lokaj-Berisha, Violeta; Lumezi, Besa

2017-10-15

Previous studies reported that familial factors such as birth order and mothers atopy might influence cord blood levels and development of allergies. The aim of the study was to evaluate the relationship of cord blood IgE and maternal IgE with birth order and mothers history of allergy in Albanian mother/neonate pairs. Study population represented 291 mother-infant pairs. Mothers were interviewed with a questionnaire for personal history of allergy and pregnancy history whereas serum IgE levels were determined using sandwich IRMA assay. The mean level of cIgE in neonates with detectable levels was 1.59 (n = 78). No significant difference in means of cIgE was found between first born and later born neonates (p = 0.232) and between neonates of mothers with a negative and positive history of allergy (p = 0.125). Also, no significant difference was found between means of mIgE by birth order, whereas there was a significant difference of mIgE between mothers with and without a history of allergy (p = 0.01). In a group of neonates with detectable cIgE levels, maternal IgE levels were moderately correlated with cIgE levels. Cord blood IgE is not affected by birth order and mothers history of allergy, whereas mothers IgE are affected by the history of allergy but not by birth order.

Variational study of the pair hopping model

International Nuclear Information System (INIS)

Fazekas, P.

1990-01-01

We study the ground state of a Hamiltonian introduced by Kolb and Penson for modelling situations in which small electron pairs are formed. The Hamiltonian consists of a tight binding band term, and a term describing the nearest neighbour hopping of electron pairs. We give a Gutzwiller-type variational treatment, first with a single-parameter Ansatz treated in the single site Gutzwiller approximation, and then with more complicated trial wave functions, and an improved Gutzwiller approximation. The calculation yields a transition from a partially paired normal state, in which the spin susceptibility has a diminished value, into a fully paired state. (author). 16 refs, 2 figs

Perturbation theory for nematic liquid crystals of axially symmetric molecules: Evaluation of fourth rank orientational order parameter

International Nuclear Information System (INIS)

Singh, K.

1993-11-01

Using a statistical mechanical perturbation theory for isotropic-nematic transition we report a calculation of second and fourth rank orientation order parameters and thermodynamic properties for a model system of prolate ellipsoids of revolution parameterized by its length-to-width ratio. The influence of attractive potential represented by dispersion interaction on a variety of thermodynamic properties is analysed. Inclusion of fourth rank orientational order parameter in calculation slightly changes the transition parameter. (author). 7 refs, 1 tab

Transverse Momentum Distributions for Heavy Quark Pairs

OpenAIRE

Berger, Edmond L.; Meng, Ruibin

1993-01-01

We study the transverse momentum distribution for a $pair$ of heavy quarks produced in hadron-hadron interactions. Predictions for the large transverse momentum region are based on exact order $\\alpha_s^3$ QCD perturbation theory. For the small transverse momentum region, we use techniques for all orders resummation of leading logarithmic contributions associated with initial state soft gluon radiation. The combination provides the transverse momentum distribution of heavy quark pairs for all...

Variation of the Pinning Force with Microstructure and with the Ginzburg-Landau Parameter in Type II Superconductors.

Science.gov (United States)

1981-09-01

quantum number in flux quantization ’n constant of the Hc (T) and the KI(T) temperature dependence n L density of pinning centers per unit length...of fluxoid ns density of Cooper pairs P pressure phase of the order parameter magnetic flux (P 0fluxoid quantum TT(r) order parameter o 0 unperturbed...tainers for controlled fusion reactors. Superconducting computers, power lines, generators, and even the superconducting magnetic- levitation of trains

Odd-frequency pairing in superconducting heterostructures .

Science.gov (United States)

Golubov, A. A.; Tanaka, Y.; Yokoyama, T.; Asano, Y.

2007-03-01

We present a general theory of the proximity effect in junctions between unconventional superconductors and diffusive normal metals (DN) or ferromagnets (DF). We consider all possible symmetry classes in a superconductor allowed by the Pauli principle: even-frequency spin-singlet even-parity state, even-frequency spin-triplet odd-parity state, odd-frequency spin-triplet even-parity state and odd-frequency spin-singlet odd-parity state. For each of the above states, symmetry and spectral properties of the induced pair amplitude in the DN (DF) are determined. The cases of junctions with spin-singlet s- and d-wave superconductors and spin-triplet p-wave superconductors are adressed in detail. We discuss the interplay between the proximity effect and midgap Andreev bound states arising at interfaces in unconventional (d- or p-wave) junctions. The most striking property is the odd-frequency symmetry of the pairing amplitude induced in DN (DF) in contacts with p-wave superconductors. This leads to zero-energy singularity in the density of states and to anomalous screening of an external magnetic field. Peculiarities of Josephson effect in d- or p-wave junctions are discussed. Experiments are suggested to detect an order parameter symmetry using heterostructures with unconventional superconductors.

Higher order structural effects stabilizing the reverse watson-crick guanine-cytosine base pair in functional RNAs

KAUST Repository

Chawla, Mohit

2013-10-10

The G:C reverse Watson-Crick (W:W trans) base pair, also known as Levitt base pair in the context of tRNAs, is a structurally and functionally important base pair that contributes to tertiary interactions joining distant domains in functional RNA molecules and also participates in metabolite binding in riboswitches. We previously indicated that the isolated G:C W:W trans base pair is a rather unstable geometry, and that dicationic metal binding to the Guanine base or posttranscriptional modification of the Guanine can increase its stability. Herein, we extend our survey and report on other H-bonding interactions that can increase the stability of this base pair. To this aim, we performed a bioinformatics search of the PDB to locate all the occurencies of G:C trans base pairs. Interestingly, 66% of the G:C trans base pairs in the PDB are engaged in additional H-bonding interactions with other bases, the RNA backbone or structured water molecules. High level quantum mechanical calculations on a data set of representative crystal structures were performed to shed light on the structural stability and energetics of the various crystallographic motifs. This analysis was extended to the binding of the preQ1 metabolite to a preQ1-II riboswitch. 2013 The Author(s).

Top Quark Pair Production in Association with a Jet with Next-to-Leading-Order QCD Off-Shell Effects at the Large Hadron Collider.

Science.gov (United States)

Bevilacqua, G; Hartanto, H B; Kraus, M; Worek, M

2016-02-05

We present a complete description of top quark pair production in association with a jet in the dilepton channel. Our calculation is accurate to next-to-leading order (NLO) in QCD and includes all nonresonant diagrams, interferences, and off-shell effects of the top quark. Moreover, nonresonant and off-shell effects due to the finite W gauge boson width are taken into account. This calculation constitutes the first fully realistic NLO computation for top quark pair production with a final state jet in hadronic collisions. Numerical results for differential distributions as well as total cross sections are presented for the Large Hadron Collider at 8 TeV. With our inclusive cuts, NLO predictions reduce the unphysical scale dependence by more than a factor of 3 and lower the total rate by about 13% compared to leading-order QCD predictions. In addition, the size of the top quark off-shell effects is estimated to be below 2%.

Continuous unitary transformation approach to pairing interactions in statistical physics

Directory of Open Access Journals (Sweden)

T.Domański

2008-06-01

Full Text Available We apply the flow equation method to the study of the fermion systems with pairing interactions which lead to the BCS instability signalled by the appearance of the off-diagonal order parameter. For this purpose we rederive the continuous Bogoliubov transformation in a fashion of renormalization group procedure where the low and high energy sectors are treated subsequently. We further generalize this procedure to the case of fermions interacting with the discrete boson mode. Andreev-type interactions are responsible for developing a gap in the excitation spectrum. However, the long-range coherence is destroyed due to strong quantum fluctuations.

Investigations into nuclear pairing

International Nuclear Information System (INIS)

Clark, R.M.

2006-01-01

This paper is divided in two main sections focusing on different aspects of collective nuclear behavior. In the first section, solutions are considered for the collective pairing Hamiltonian. In particular, an approximate solution at the critical point of the pairing transition from harmonic vibration (normal nuclear behavior) to deformed rotation (superconducting behavior) in gauge space is found by analytic solution of the Hamiltonian. The eigenvalues are expressed in terms of the zeros of Bessel functions of integer order. The results are compared to the pairing bands based on the Pb isotopes. The second section focuses on the experimental search for the Giant Pairing Vibration (GPV) in nuclei. After briefly describing the origin of the GPV, and the reasons that the state has remained unidentified, a novel idea for populating this state is presented. A recent experiment has been performed using the LIBERACE+STARS detector system at the 88-Inch Cyclotron of LBNL to test the idea. (Author)

Dynamical susceptibility near a long-wavelength critical point with a nonconserved order parameter

Science.gov (United States)

Klein, Avraham; Lederer, Samuel; Chowdhury, Debanjan; Berg, Erez; Chubukov, Andrey

2018-04-01

We study the dynamic response of a two-dimensional system of itinerant fermions in the vicinity of a uniform (Q =0 ) Ising nematic quantum critical point of d - wave symmetry. The nematic order parameter is not a conserved quantity, and this permits a nonzero value of the fermionic polarization in the d - wave channel even for vanishing momentum and finite frequency: Π (q =0 ,Ωm)≠0 . For weak coupling between the fermions and the nematic order parameter (i.e., the coupling is small compared to the Fermi energy), we perturbatively compute Π (q =0 ,Ωm)≠0 over a parametrically broad range of frequencies where the fermionic self-energy Σ (ω ) is irrelevant, and use Eliashberg theory to compute Π (q =0 ,Ωm) in the non-Fermi-liquid regime at smaller frequencies, where Σ (ω )>ω . We find that Π (q =0 ,Ω ) is a constant, plus a frequency-dependent correction that goes as |Ω | at high frequencies, crossing over to |Ω| 1 /3 at lower frequencies. The |Ω| 1 /3 scaling holds also in a non-Fermi-liquid regime. The nonvanishing of Π (q =0 ,Ω ) gives rise to additional structure in the imaginary part of the nematic susceptibility χ″(q ,Ω ) at Ω >vFq , in marked contrast to the behavior of the susceptibility for a conserved order parameter. This additional structure may be detected in Raman scattering experiments in the d - wave geometry.

Fractional Order Controller Designing with Firefly Algorithm and Parameter Optimization for Hydroturbine Governing System

Directory of Open Access Journals (Sweden)

Li Junyi

2015-01-01

Full Text Available A fractional order PID (FOPID controller, which is suitable for control system designing for being insensitive to the variation in system parameter, is proposed for hydroturbine governing system in the paper. The simultaneous optimization for several parameters of controller, that is, Ki, Kd, Kp, λ, and μ, is done by a recently developed metaheuristic nature-inspired algorithm, namely, the firefly algorithm (FA, for the first time, where the selecting, moving, attractiveness behavior between fireflies and updating of brightness, and decision range are studied in detail to simulate the optimization process. Investigation clearly reveals the advantages of the FOPID controller over the integer controllers in terms of reduced oscillations and settling time. The present work also explores the superiority of FA based optimization technique in finding optimal parameters of the controller. Further, convergence characteristics of the FA are compared with optimum integer order PID (IOPID controller to justify its efficiency. What is more, analysis confirms the robustness of FOPID controller under isolated load operation conditions.

Spatial variations of order parameter around Kondo impurity for T<=Tsub(c)

International Nuclear Information System (INIS)

Yoksan, S.

1980-04-01

Analytic expressions for the spatial variations of the order parameter around a Kondo impurity are obtained. The oscillatory contribution due to the impurity scattering is calculated using the t matrix of Matsuura which conveniently yields the general results below Tsub(c). Differences between our values and those of Schlottmann are reported. (author)

Derivation of the spin-glass order parameter from stochastic thermodynamics

Science.gov (United States)

Crisanti, A.; Picco, M.; Ritort, F.

2018-05-01

A fluctuation relation is derived to extract the order parameter function q (x ) in weakly ergodic systems. The relation is based on measuring and classifying entropy production fluctuations according to the value of the overlap q between configurations. For a fixed value of q , entropy production fluctuations are Gaussian distributed allowing us to derive the quasi-FDT so characteristic of aging systems. The theory is validated by extracting the q (x ) in various types of glassy models. It might be generally applicable to other nonequilibrium systems and experimental small systems.

Comparisons of perturbation and integral equation theories for the angular pair correlation function in molecular fluids

International Nuclear Information System (INIS)

Murad, S.; Gubbins, K.E.; Gray, C.G.

1983-01-01

We compare several recently proposed theories for the angular pair correlation function g(rω 1 ω 2 ), including first- and second-order perturbation theory (the u-expansion), a Pade approximant to this series, first-order f-expansion, the single superchain, generalized mean field, linearized hypernetted chain, and quadratic hypernetted chain approximations. Numerical results from these theories are compared with available computer simulation data for four model fluids whose intermolecular pair potential is of the form u 0 +usub(a), where u 0 is a hard-sphere of Lennard-Jones model, while usub(a) is a dipole-dipole or quadrupole-quadrupole interaction; we refer to these model fluids as HS+μμ, HS+QQ, LJ+μμ, and LJ+QQ. Properties studied include the angular pair correlation function and its spherical harmonic components, the thermodynamic properties, and the angular correlation parameters G 1 and G 2 that are related to the dielectric and Kerr constants. The second-order perturbation theory is superior to the integral equation theories for the thermodynamic harmonics of g(rω 1 ω 2 ) and for the thermodynamic properties themselves at moderate multipole strengths. For other harmonics and properties, the integral equation theories are better, with the quadratic hypernetted chain approximation being the best overall. (orig.)

Intertwined Orders in Heavy-Fermion Superconductor CeCoIn_{5}

Directory of Open Access Journals (Sweden)

Duk Y. Kim

2016-12-01

Full Text Available The appearance of spin-density-wave (SDW magnetic order in the low-temperature and high-field corner of the superconducting phase diagram of CeCoIn_{5} is unique among unconventional superconductors. The nature of this magnetic Q phase is a matter of current debate. Here, we present the thermal conductivity of CeCoIn_{5} in a rotating magnetic field, which reveals the presence of an additional order inside the Q phase that is intimately intertwined with the superconducting d-wave and SDW orders. A discontinuous change of the thermal conductivity within the Q phase, when the magnetic field is rotated about antinodes of the superconducting d-wave order parameter, demands that the additional order must change abruptly, together with the recently observed switching of the SDW. A combination of interactions, where spin-orbit coupling orients the SDW, which then selects the secondary p-wave pair-density-wave component (with an average amplitude of 20% of the primary d-wave order parameter, accounts for the observed behavior.

Statistical deprojection of galaxy pairs

Science.gov (United States)

Nottale, Laurent; Chamaraux, Pierre

2018-06-01

Aims: The purpose of the present paper is to provide methods of statistical analysis of the physical properties of galaxy pairs. We perform this study to apply it later to catalogs of isolated pairs of galaxies, especially two new catalogs we recently constructed that contain ≈1000 and ≈13 000 pairs, respectively. We are particularly interested by the dynamics of those pairs, including the determination of their masses. Methods: We could not compute the dynamical parameters directly since the necessary data are incomplete. Indeed, we only have at our disposal one component of the intervelocity between the members, namely along the line of sight, and two components of their interdistance, i.e., the projection on the sky-plane. Moreover, we know only one point of each galaxy orbit. Hence we need statistical methods to find the probability distribution of 3D interdistances and 3D intervelocities from their projections; we designed those methods under the term deprojection. Results: We proceed in two steps to determine and use the deprojection methods. First we derive the probability distributions expected for the various relevant projected quantities, namely intervelocity vz, interdistance rp, their ratio, and the product rp v_z^2, which is involved in mass determination. In a second step, we propose various methods of deprojection of those parameters based on the previous analysis. We start from a histogram of the projected data and we apply inversion formulae to obtain the deprojected distributions; lastly, we test the methods by numerical simulations, which also allow us to determine the uncertainties involved.

On e(+)e(-) pair production by colliding electromagnetic pulses

NARCIS (Netherlands)

Narozhny, NB; Bulanov, SS; Mur, VD; Popov, VS

2004-01-01

Electron-positron pair production from vacuum in an electromagnetic field created by two counterpropagating focused laser pulses interacting with each other is analyzed. The dependence of the number of produced pairs on the intensity of a laser pulse and the focusing parameter is studied with a

Quantum saturation of the order parameter and the dynamical soft mode in quartz

CERN Document Server

Romero, F J

2003-01-01

The temperature evolution of the static order parameter of alpha-quartz and its soft-mode frequencies were determined at temperatures below 300 K. While these parameters follow classic Landau theory at higher temperatures, quantum saturation was found below room temperature with a characteristic quantum temperature of 187 K. A quantitative analysis gave a good agreement with the predictions of a PHI sup 6 model close to the displacive limit and a rather flat dispersion of the soft-mode branch. No indication of any effect of strong mode-mode coupling on the saturation behaviour was observed.

Novel experimental methodology for the characterization of thermodynamic performance of advanced working pairs for adsorptive heat transformers

International Nuclear Information System (INIS)

Frazzica, Andrea; Sapienza, Alessio; Freni, Angelo

2014-01-01

This paper presents a novel experimental protocol for the evaluation of the thermodynamic performance of working pairs for application in adsorption heat pumps and chillers. The proposed approach is based on the experimental measurements of the main thermo-physical parameters of adsorbent pairs, by means of a DSC/TG apparatus modified to work under saturated vapour conditions, able to measure the ads-/desorption isobars and heat flux as well as the adsorbent specific heat under real boundary conditions. Such kind of activity allows to characterize the thermodynamic performance of an adsorbent pair allowing the estimation of the thermal Coefficient Of Performance (COP) both for heating and cooling applications, only relying on experimental values. The experimental uncertainty of the method has been estimated to be around 2%, for the COP evaluation. In order to validate the proposed procedure, a first test campaign has been carried out on the commercial adsorbent material, AQSOA-Z02, produced by MPI (Mitsubishi Plastics Inc.), while water was used as refrigerant. The proposed experimental methodology will be applied on several other adsorbent materials, either already on the market or still under investigation, in order to get an easy and reliable method to compare thermodynamic performance of adsorptive working pairs

BEC-BCS crossover in a (p+ip)-wave pairing Hamiltonian coupled to bosonic molecular pairs

International Nuclear Information System (INIS)

Dunning, Clare; Isaac, Phillip S.; Links, Jon; Zhao, Shao-You

2011-01-01

We analyse a (p+ip)-wave pairing BCS Hamiltonian, coupled to a single bosonic degree of freedom representing a molecular condensate, and investigate the nature of the BEC-BCS crossover for this system. For a suitable restriction on the coupling parameters, we show that the model is integrable and we derive the exact solution by the algebraic Bethe ansatz. In this manner we also obtain explicit formulae for correlation functions and compute these for several cases. We find that the crossover between the BEC state and the strong pairing p+ip phase is smooth for this model, with no intermediate quantum phase transition.

Theory of superconductivity with non-Hermitian and parity-time reversal symmetric Cooper pairing symmetry

Science.gov (United States)

Ghatak, Ananya; Das, Tanmoy

2018-01-01

Recently developed parity (P ) and time-reversal (T ) symmetric non-Hermitian systems govern a rich variety of new and characteristically distinct physical properties, which may or may not have a direct analog in their Hermitian counterparts. We study here a non-Hermitian, PT -symmetric superconducting Hamiltonian that possesses a real quasiparticle spectrum in the PT -unbroken region of the Brillouin zone. Within a single-band mean-field theory, we find that real quasiparticle energies are possible when the superconducting order parameter itself is either Hermitian or anti-Hermitian. Within the corresponding Bardeen-Cooper-Schrieffer (BCS) theory, we find that several properties are characteristically distinct and novel in the non-Hermitian pairing case than its Hermitian counterpart. One of our significant findings is that while a Hermitian superconductor gives a second-order phase transition, the non-Hermitian one produces a robust first-order phase transition. The corresponding thermodynamic properties and the Meissner effect are also modified accordingly. Finally, we discuss how such a PT -symmetric pairing can emerge from an antisymmetric potential, such as the Dzyloshinskii-Moriya interaction, but with an external bath, or complex potential, among others.

Multiple electromagnetic electron-positron pair production in relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Alscher, A.; Hencken, K.; Trautmann, D.; Baur, G.

1997-01-01

We calculate the cross sections for the production of one and more electron-positron pairs due to the strong electromagnetic fields in relativistic heavy-ion collisions. We derive the N-pair amplitude using the generating functional of fermions in an external field and the path-integral formalism. The N-pair production probability is found to be an approximate Poisson distribution. We calculate total cross sections for the production of one pair in lowest order, including corrections from the Poisson distribution up to third order. Furthermore, we calculate cross sections for the production of up to five pairs including corrections from the Poisson distribution. copyright 1997 The American Physical Society

Heavy-quark pair production in gluon fusion at next-to-next-to-leading O(α4s) order. One-loop squared contributions

International Nuclear Information System (INIS)

Kniehl, B.A.; Merebashvili, Z.

2008-09-01

We calculate the next-to-next-to-leading order O(α 4 s ) one-loop squared corrections to the production of heavy quark pairs in the gluon-gluon fusion process. Together with the previously derived results on the q anti q production channel the results of this paper complete the calculation of the oneloop squared contributions of the next-to-next-to-leading order O(α 4 s ) radiative QCD corrections to the hadroproduction of heavy flavours. Our results, with the full mass dependence retained, are presented in a closed and very compact form, in dimensional regularization. (orig.)

Exchange and spin-fluctuation superconducting pairing in the strong correlation limit of the Hubbard model

International Nuclear Information System (INIS)

Plakida, N. M.; Anton, L.; Adam, S. . Department of Theoretical Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, PO Box MG-6, RO-76900 Bucharest - Magurele; RO); Adam, Gh. . Department of Theoretical Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, PO Box MG-6, RO-76900 Bucharest - Magurele; RO)

2001-01-01

A microscopical theory of superconductivity in the two-band singlet-hole Hubbard model, in the strong coupling limit in a paramagnetic state, is developed. The model Hamiltonian is obtained by projecting the p-d model to an asymmetric Hubbard model with the lower Hubbard subband occupied by one-hole Cu d-like states and the upper Hubbard subband occupied by two-hole p-d singlet states. The model requires two microscopical parameters only, the p-d hybridization parameter t and the charge-transfer gap Δ. It was previously shown to secure an appropriate description of the normal state properties of the high -T c cuprates. To treat rigorously the strong correlations, the Hubbard operator technique within the projection method for the Green function is used. The Dyson equation is derived. In the molecular field approximation, d-wave superconducting pairing of conventional hole (electron) pairs in one Hubbard subband is found, which is mediated by the exchange interaction given by the interband hopping, J ij = 4 (t ij ) 2 / Δ. The normal and anomalous components of the self-energy matrix are calculated in the self-consistent Born approximation for the electron-spin-fluctuation scattering mediated by kinematic interaction of the second order of the intraband hopping. The derived numerical and analytical solutions predict the occurrence of singlet d x 2 -y 2 -wave pairing both in the d-hole and singlet Hubbard subbands. The gap functions and T c are calculated for different hole concentrations. The exchange interaction is shown to be the most important pairing interaction in the Hubbard model in the strong correlation limit, while the spin-fluctuation coupling results only in a moderate enhancement of T c . The smaller weight of the latter comes from two specific features: its vanishing inside the Brillouin zone (BZ) along the lines, |k x | + |k y |=π pointing towards the hot spots and the existence of a small energy shell within which the pairing is effective. By

Pairing interaction method in crystal field theory

International Nuclear Information System (INIS)

Dushin, R.B.

1989-01-01

Expressions, permitting to describe matrix elements of secular equation for metal-ligand pairs via parameters of the method of pairing interactions, genealogical coefficients and Clebsch-Gordan coefficients, are given. The expressions are applicable to any level or term of f n and d n configurations matrix elements for the terms of the maximum multiplicity of f n and d n configurations and also for the main levels of f n configurations are tabulated

Reduced-order modelling of parameter-dependent, linear and nonlinear dynamic partial differential equation models.

Science.gov (United States)

Shah, A A; Xing, W W; Triantafyllidis, V

2017-04-01

In this paper, we develop reduced-order models for dynamic, parameter-dependent, linear and nonlinear partial differential equations using proper orthogonal decomposition (POD). The main challenges are to accurately and efficiently approximate the POD bases for new parameter values and, in the case of nonlinear problems, to efficiently handle the nonlinear terms. We use a Bayesian nonlinear regression approach to learn the snapshots of the solutions and the nonlinearities for new parameter values. Computational efficiency is ensured by using manifold learning to perform the emulation in a low-dimensional space. The accuracy of the method is demonstrated on a linear and a nonlinear example, with comparisons with a global basis approach.

Leading order determination of the gluon polarisation from DIS events with high-$p_T$ hadron pairs

CERN Document Server

Adolph, C; Alexakhin, V Yu; Alexandrov, Yu; Alexeev, G D; Amoroso, A; Antonov, A A; Austregesilo, A; Badelek, B; Balestra, F; Barth, J; Baum, G; Bedfer, Y; Bernhard, J; Bertini, R; Bettinelli, M; Bicker, K; Bieling, J; Birsa, R; Bisplinghoff, J; Bordalo, P; Bradamante, F; Braun, C; Bravar, A; Bressan, A; Burtin, E; Chaberny, D; Chiosso, M; Chung, S U; Cicuttin, A; Crespo, M L; Dalla Torre, S; Das, S; Dasgupta, S S; Denisov, O.Yu; Dhara, L; Donskov, S V; Doshita, N; Duic, V; Dunnweber, W; Dziewiecki, M; Efremov, A; Elia, C; Eversheim, P D; Eyrich, W; Faessler, M; Ferrero, A; Filin, A; Finger, M; jr., M.Finger; Fischer, H; Franco, C; von Hohenesche, N.du Fresne; Friedrich, J M; Garfagnini, R; Gautheron, F; Gavrichtchouk, O P; Gazda, R; Gerassimov, S; Geyer, R; Giorgi, M; Gnesi, I; Gobbo, B; Goertz, S; Grabmuller, S; Grasso, A; Grube, B; Gushterski, R; Guskov, A; Guthorl, T; Haas, F; von Harrach, D; Hedicke, S; Heinsius, F H; Herrmann, F; Hess, C; Hinterberger, F; Horikawa, N; Hoppner, Ch; d'Hose, N; Huber, S; Ishimoto, S; Ivanov, O; Ivanshin, Yu; Iwata, T; Jahn, R; Jasinski, P; Joosten, R; Kabuss, E; Kang, D; Ketzer, B; Khaustov, G V; Khokhlov, Yu.A; Kisselev, Yu; Klein, F; Klimaszewski, K; Koblitz, S; Koivuniemi, J H; Kolosov, V N; Kondo, K; Konigsmann, K; Konorov, I; Konstantinov, V F; Korzenev, A; Kotzinian, A M; Kouznetsov, O; Kramer, M; Kroumchtein, Z V; Kunne, F.; Kurek, K; Lauser, L; Le Goff, J M; Lednev, A A; Lehmann, A; Levorato, S; Lichtenstadt, J; Maggiora, A; Magnon, A; Makke, N; Mallot, G K; Mann, A; Marchand, C; Martin, A; Marzec, J; Matsuda, T; Meyer, W; Michigami, T; Mikhailov, Yu.V; Moinester, M A; Morreale, A; Mutter, A; Nagaytsev, A; Nagel, T; Nassalski, J P; Nerling, F; Neubert, S; Neyret, D; Nikolaenko, V I; Nowak, W D; Nunes, A S; Olshevsky, A G; Ostrick, M; Padee, A; Panknin, R; Panzieri, D; Parsamyan, B; Paul, S.; Perevalova, E; Pesaro, G; Peshekhonov, D V; Piragino, G; Platchkov, S; Pochodzalla, J; Polak, J; Polyakov, V A; Pontecorvo, G; Pretz, J; Procureur, S L; Quaresma, M; Quintans, C; Rajotte, J F; Ramos, S; Rapatsky, V; Reicherz, G; Richter, A; Rocco, E; Rondio, E; Rossiyskaya, N S; Ryabchikov, D I; Samoylenko, V D; Sandacz, A; Sapozhnikov, M G; Sarkar, S.; Savin, I A; Sbrizzai, G; Schiavon, P; Schill, C.; Schluter, T; Schmidt, K; Schmitt, L; Schonning, K; Schopferer, S; Schott, M; Shevchenko, O.Yu; Silva, L; Sinha, L; Sissakian, A N; Slunecka, M; Smirnov, G I; Sosio, S; Sozzi, F; Srnka, A; Stolarski, M; Sulc, M; Sulej, R; Sznajder, P; Takekawa, S; Wolbeek, J.Ter; Tessaro, S; Tessarotto, F; Tkatchev, L G; Uhl, S; Uman, I; Vandenbroucke, M; Virius, M; Vlassov, N V; Wang, L; Windmolders, R; Wislicki, W; Wollny, H; Zaremba, K; Zavertyaev, M; Zemlyanichkina, E; Ziembicki, M; Zhuravlev, N; Zvyagin, A

2013-01-01

We present a determination of the gluon polarisation Delta g/g in the nucleon, based on the longitudinal double-spin asymmetry of DIS events with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam scattering off a polarised ^6LiD target. The gluon polarisation is evaluated by a Neural Network approach for three intervals of the gluon momentum fraction x_g covering the range 0.04 < x_g < 0.27. The values obtained at leading order in QCD do not show any significant dependence on x_g. Their average is Delta g/g = 0.125 +/- 0.060 (stat.) +/- 0.063 (syst.) at x_g=0.09 and a scale of mu^2 = 3~(GeV/c)^2.

Inadmissibility of Usual and Mixed Estimators of Two Ordered Gamma Scale Parameters Under Reflected Gamma Loss Function

Directory of Open Access Journals (Sweden)

Z. Meghnatisi

2009-06-01

Full Text Available Let Xi1, · · · , Xini be a random sample from a gamma distribution with known shape parameter νi > 0 and unknown scale parameter βi > 0, i = 1, 2, satisfying 0 < β1 6 β2. We consider the class of mixed estimators for estimation of β1 and β2 under reflected gamma loss function. It has been shown that the minimum risk equivariant estimator of βi, i = 1, 2, which is admissible when no information on the ordering of parameters are given, is inadmissible and dominated by a class of mixed estimators when it is known that the parameters are ordered. Also, the inadmissible estimators in the class of mixed estimators are derived. Finally the results are extended to some subclass of exponential family

Metal-mediated DNA base pairing: alternatives to hydrogen-bonded Watson-Crick base pairs.

Science.gov (United States)

Takezawa, Yusuke; Shionoya, Mitsuhiko

2012-12-18

With its capacity to store and transfer the genetic information within a sequence of monomers, DNA forms its central role in chemical evolution through replication and amplification. This elegant behavior is largely based on highly specific molecular recognition between nucleobases through the specific hydrogen bonds in the Watson-Crick base pairing system. While the native base pairs have been amazingly sophisticated through the long history of evolution, synthetic chemists have devoted considerable efforts to create alternative base pairing systems in recent decades. Most of these new systems were designed based on the shape complementarity of the pairs or the rearrangement of hydrogen-bonding patterns. We wondered whether metal coordination could serve as an alternative driving force for DNA base pairing and why hydrogen bonding was selected on Earth in the course of molecular evolution. Therefore, we envisioned an alternative design strategy: we replaced hydrogen bonding with another important scheme in biological systems, metal-coordination bonding. In this Account, we provide an overview of the chemistry of metal-mediated base pairing including basic concepts, molecular design, characteristic structures and properties, and possible applications of DNA-based molecular systems. We describe several examples of artificial metal-mediated base pairs, such as Cu(2+)-mediated hydroxypyridone base pair, H-Cu(2+)-H (where H denotes a hydroxypyridone-bearing nucleoside), developed by us and other researchers. To design the metallo-base pairs we carefully chose appropriate combinations of ligand-bearing nucleosides and metal ions. As expected from their stronger bonding through metal coordination, DNA duplexes possessing metallo-base pairs exhibited higher thermal stability than natural hydrogen-bonded DNAs. Furthermore, we could also use metal-mediated base pairs to construct or induce other high-order structures. These features could lead to metal-responsive functional

Effects of disorder on the electron pairing

International Nuclear Information System (INIS)

Oviedo-Roa, R.; Wang, C.; Navarro, O.

1996-01-01

The electron pairing in randomly disordered lattices is studied by using an attractive Hubbard model, and by mapping the many-body problem onto a tight-binding one in a higher dimensional space, where a diagonal disorder is considered within the coherent-potential approximation. The results show an enhancement of the pair-binding energy as the self-energy difference increases in a binary alloy A x B 1-x . This fact suggests that the pairing process is highly sensitive to the one-particle localization condition. A ground-state phase diagram for on-site interaction disorder shows regions where pairing is avoided for ordered diatomic systems but not for disordered case

Pair Identity and Smooth Variation Rules Applicable for the Spectroscopic Parameters of H2O Transitions Involving High-J States

Science.gov (United States)

Ma, Q.; Tipping, R. H.; Lavrentieva, N. N.

2010-01-01

Two basic rules (i.e. the pair identity and the smooth variation) applicable for H2O transitions involving high-J states have been discovered. The origins of these rules are the properties of the energy levels and wavefunctions of H2O states with the quantum number J above certain boundaries. As a result, for lines involving high-J states in individually defined groups, all their spectroscopic parameters (i.e. the transition wavenumber, intensity, pressure-broadened half-width, pressure-induced shift, and temperature exponent) must follow these rules. One can use these rules to screen spectroscopic data provided by databases and to identify possible errors. In addition, by using extrapolation methods within the individual groups, one is able to predict the spectroscopic parameters for lines in this group involving very high-J states. The latter are required in developing high-temperature molecular spectroscopic databases such as HITEMP.

Mutual information as an order parameter for quantum synchronization

Science.gov (United States)

Ameri, V.; Eghbali-Arani, M.; Mari, A.; Farace, A.; Kheirandish, F.; Giovannetti, V.; Fazio, R.

2015-01-01

Spontaneous synchronization is a fundamental phenomenon, important in many theoretical studies and applications. Recently, this effect has been analyzed and observed in a number of physical systems close to the quantum-mechanical regime. In this work we propose mutual information as a useful order parameter which can capture the emergence of synchronization in very different contexts, ranging from semiclassical to intrinsically quantum-mechanical systems. Specifically, we first study the synchronization of two coupled Van der Pol oscillators in both classical and quantum regimes and later we consider the synchronization of two qubits inside two coupled optical cavities. In all these contexts, we find that mutual information can be used as an appropriate figure of merit for determining the synchronization phases independently of the specific details of the system.

Excited cooper pairs

Energy Technology Data Exchange (ETDEWEB)

Lopez-Arrietea, M. G.; Solis, M. A.; De Llano, M. [Universidad Nacional Autonoma de Mexico, Mexico, D.F (Mexico)

2001-02-01

Excited cooper pairs formed in a many-fermion system are those with nonzero total center-of mass momentum (CMM). They are normally neglected in the standard Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity for being too few compared with zero CMM pairs. However, a Bose-Einstein condensation picture requires both zero and nonzero CMM pairs. Assuming a BCS model interaction between fermions we determine the populations for all CMM values of Cooper pairs by actually calculating the number of nonzero-CMM pairs relative to that of zero-CMM ones in both 2D and 3D. Although this ratio decreases rapidly with CMM, the number of Cooper pairs for any specific CMM less than the maximum (or breakup of the pair) momentum turns out to be typically larger than about 95% of those with zero-CMM at zero temperature T. Even at T {approx}100 K this fraction en 2D is still as large as about 70% for typical quasi-2D cuprate superconductor parameters. [Spanish] Los pares de cooper excitados formados en un sistema de muchos electrones, son aquellos con momentos de centro de masa (CMM) diferente de cero. Normalmente estos no son tomados en cuenta en la teoria estandar de la superconductividad de Bardeen-Cooper-Schrieffer (BCS) al suponer que su numero es muy pequeno comparados con los pares de centro de masa igual a cero. Sin embargo, un esquema de condensacion Bose-Einstein requiere de ambos pares, con CMM cero y diferente de cero. Asumiendo una interaccion modelo BCS entre los fermiones, determinamos la poblacion de pares cooper con cada uno de todos los posibles valores del CMM calculando el numero de pares con momentos de centro de masa diferente de cero relativo a los pares de CMM igual a cero, en 2D y 3D. Aunque esta razon decrece rapidamente con el CMM, el numero de pares de cooper para cualquier CMM especifico menor que el momento maximo (o rompimiento de par) es tipicamente mas grande que el 95% de aquellos con CMM cero. Aun a T {approx}100 K esta fraccion en 2D es

Next-to-next-to-leading order O({alpha}{sup 2}{alpha}{sup 2}{sub s}) results for top quark pair production in photon-photon collisions. The loop-by-loop contribution

Energy Technology Data Exchange (ETDEWEB)

Koerner, J.G. [Johannes Gutenberg Univ., Mainz (Germany). Inst. fuer Phys.; Merebashvili, Z. [Tbilisi State Univ. (Georgia). Inst. of High Energy Physics and Informatization; Rogal, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2006-08-15

We calculate the so-called loop-by-loop contributions to the next-to-next-to-leading order O({alpha}{sup 2}{alpha}{sup 2}{sub s}) radiative QCD corrections for the production of heavy quark pairs in the collisions of unpolarized on-shell photons. In particular, we present analytical results for the squared matrix elements that correspond to the product of the one-loop amplitudes. All results of the perturbative calculation are given in the dimensional regularization scheme. These results represent the Abelian part of the corresponding gluon-induced next-to-next-to-leading order cross section for heavy quark pair hadroproduction. (orig.)

A possible non-pairing mechanism for high-Tsub(c) perfect conductors in two dimensions

International Nuclear Information System (INIS)

Lee, Y.C.

1987-01-01

We have generalised Froehlich's model of 1D superconductivity to systems with 2D layers associated with nearly nested Fermi surfaces. In the ground state phonons with wavevectors that span opposite sides of the Fermi surface are found to have coherent, macroscopic amplitudes when they are coupled resonantly to the corresponding electron density waves. Umklapp processes notwithstanding. These quantum mechanical wave amplitudes constitute the order parameter of the system, decreasing to zero as T → Tsub(c), the critical temperature. They also give rise to a temperature-dependent energy gap. In the absence of Umklapp processes, such a gap would lead to perfect conductivity for T < Tsub(c), as for the original 1D version given by Froehlich. The scale of Tsub(c) is determined by the much higher εsub(F), rather than by ωsub(D); hence also the absence of an isotope effect. This model, with independent electrons and phonons and the associated order parameter, should serve as a new and significantly different zeroth-order system, a springboard from which BCS pairing could then be built. (author)

Studies of wheel-running reinforcement: parameters of Herrnstein's (1970) response-strength equation vary with schedule order.

Science.gov (United States)

Belke, T W

2000-05-01

Six male Wistar rats were exposed to different orders of reinforcement schedules to investigate if estimates from Herrnstein's (1970) single-operant matching law equation would vary systematically with schedule order. Reinforcement schedules were arranged in orders of increasing and decreasing reinforcement rate. Subsequently, all rats were exposed to a single reinforcement schedule within a session to determine within-session changes in responding. For each condition, the operant was lever pressing and the reinforcing consequence was the opportunity to run for 15 s. Estimates of k and R(O) were higher when reinforcement schedules were arranged in order of increasing reinforcement rate. Within a session on a single reinforcement schedule, response rates increased between the beginning and the end of a session. A positive correlation between the difference in parameters between schedule orders and the difference in response rates within a session suggests that the within-session change in response rates may be related to the difference in the asymptotes. These results call into question the validity of parameter estimates from Herrnstein's (1970) equation when reinforcer efficacy changes within a session.

Crystal nucleation in binary hard-sphere mixtures: the effect of order parameter on the cluster composition

NARCIS (Netherlands)

Ni, R.; Smallenburg, F.; Filion, L.C.; Dijkstra, M.

2011-01-01

We study crystal nucleation in a binary mixture of hard spheres and investigate the composition and size of the (non)critical clusters using Monte Carlo simulations. In order to study nucleation of a crystal phase in computer simulations, a one-dimensional order parameter is usually defined to

Generalizing the order and the parameters of macro-operators by explanation-based learning - Extension of Explanation-Based Learning on Partial Order

International Nuclear Information System (INIS)

Li, Huihua

1992-01-01

The traditional generalization methods such as FIKE's macro-operator learning and Explanation-Based Learning (EBL) deal with totally ordered plans. They generalize only the plan operators and the conditions under which the generalized plan can be applied in its initial total order, but not the partial order among operators in which the generalized plan can be successfully executed. In this paper, we extend the notion of the EBL on the partial order of plans. A new method is presented for learning, from a totally or partially ordered plan, partially ordered macro-operators (generalized plans) each of which requires a set of the weakest conditions for its reuse. It is also valuable for generalizing partially ordered plans. The operators are generalized in the FIKE's triangle table. We introduce the domain axioms to generate the constraints for the consistency of generalized states. After completing the triangle table with the information concerning the operator destructions (interactions), we obtain the global explanation of the partial order on the operators. Then, we represent all the necessary ordering relations by a directed graph. The exploitation of this graph permits to explicate the dependence between the partial orders and the constraints among the parameters of generalized operators, and allows all the solutions to be obtained. (author) [fr

Transport and pairing properties of helical edges with proximity induced superconductivity and ferromagnetism

Energy Technology Data Exchange (ETDEWEB)

Keidel, Felix; Burset, Pablo; Trauzettel, Bjoern [Institute of Theoretical Physics and Astrophysics, University of Wuerzburg, 97074 Wuerzburg (Germany); Crepin, Francois [Laboratoire de Physique Theorique de la Matiere Condensee, UPMC, Sorbonne Universites, 75252 Paris (France)

2016-07-01

The scientific interest in Quantum Spin Hall systems is far from declining. While these certainly are fascinating by themselves, there is plenty of new and exciting physics to arise when superconductivity and ferromagnetism are brought into the game. The strong constraint of helicity in the edge states of a two-dimensional topological insulator is responsible for an intimate relation between the allowed scattering processes in a hybrid junction and the parameters of the system, namely the superconducting order parameter and the magnetic field. In our work, we study a helical liquid in proximity to a conventional s-wave superconductor and ferromagnetic insulators by means of a Green's function analysis. The ferromagnet gives rise to sub-gap Andreev/Majorana bound states and non-local crossed Andreev reflection (CAR), both of which decisively affect the pairing and transport properties of the junction. As a result, the simple s-wave symmetry of the superconductor is enriched and unconventional odd-frequency triplet superconductivity emerges. Strikingly, we have identified a setup that favors CAR over electron co-tunneling and may allow for the indirect measurement of the symmetries of the superconducting order parameter.

Minimum of the order parameter fluctuations of seismicity before major earthquakes in Japan.

Science.gov (United States)

Sarlis, Nicholas V; Skordas, Efthimios S; Varotsos, Panayiotis A; Nagao, Toshiyasu; Kamogawa, Masashi; Tanaka, Haruo; Uyeda, Seiya

2013-08-20

It has been shown that some dynamic features hidden in the time series of complex systems can be uncovered if we analyze them in a time domain called natural time χ. The order parameter of seismicity introduced in this time domain is the variance of χ weighted for normalized energy of each earthquake. Here, we analyze the Japan seismic catalog in natural time from January 1, 1984 to March 11, 2011, the day of the M9 Tohoku earthquake, by considering a sliding natural time window of fixed length comprised of the number of events that would occur in a few months. We find that the fluctuations of the order parameter of seismicity exhibit distinct minima a few months before all of the shallow earthquakes of magnitude 7.6 or larger that occurred during this 27-y period in the Japanese area. Among the minima, the minimum before the M9 Tohoku earthquake was the deepest. It appears that there are two kinds of minima, namely precursory and nonprecursory, to large earthquakes.

Spectral Properties, Generation Order Parameters, and Luminosities for Spin-powered X-Ray Pulsars

Science.gov (United States)

Wang, Wei; Zhao, Yongheng

2004-02-01

We show the spectral properties of 15 spin-powered X-ray pulsars, and the correlation between the average power-law photon index and spin-down rate. Generation order parameters (GOPs) based on polar cap models are introduced to characterize the X-ray pulsars. We calculate three definitions of generation order parameters arising from the different effects of magnetic and electric fields on photon absorption during cascade processes, and study the relations between the GOPs and spectral properties of X-ray pulsars. There exists a possible correlation between the photon index and GOP in our pulsar sample. Furthermore, we present a method stemming from the concept of GOPs to estimate the nonthermal X-ray luminosity for spin-powered pulsars. Then X-ray luminosity is calculated in the context of our polar cap accelerator model, which is consistent with most observed X-ray pulsar data. The ratio between the X-ray luminosity estimated by our method and the pulsar's spin-down power is consistent with the LX~10-3Lsd feature.

Exclusive electroproduction of pion pairs

International Nuclear Information System (INIS)

Warkentin, N.; Schaefer, A.; Diehl, M.; Ivanov, D. Yu.

2007-01-01

We investigate electroproduction of pion pairs on the nucleon in the framework of QCD factorization for hard exclusive processes. We extend previous analyses by taking the hard-scattering coefficients at next-to-leading order in α s . The dynamics of the produced pion pair is described by two-pion distribution amplitudes, for which we perform a detailed theoretical and phenomenological analysis. In particular, we obtain constraints on these quantities by comparing our results with measurements of angular observables that are sensitive to the interference between two-pion production in the isoscalar and isovector channels. (orig.)

Detecting nonlocal Cooper pair entanglement by optical Bell inequality violation

Energy Technology Data Exchange (ETDEWEB)

Nigg, Simon E.; Tiwari, Rakesh P.; Walter, Stefan; Schmidt, Thomas L. [Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland)

2015-07-01

Based on the Bardeen Cooper Schrieffer (BCS) theory of superconductivity, the coherent splitting of Cooper pairs from a superconductor to two spatially separated quantum dots has been predicted to generate nonlocal pairs of entangled electrons. In order to test this hypothesis, we propose a scheme to transfer the spin state of a split Cooper pair onto the polarization state of a pair of optical photons. We show that the produced photon pairs can be used to violate a Bell inequality, unambiguously demonstrating the entanglement of the split Cooper pairs.

Detecting nonlocal Cooper pair entanglement by optical Bell inequality violation

Science.gov (United States)

Nigg, Simon E.; Tiwari, Rakesh P.; Walter, Stefan; Schmidt, Thomas L.

2015-03-01

Based on the Bardeen-Cooper-Schrieffer theory of superconductivity, the coherent splitting of Cooper pairs from a superconductor to two spatially separated quantum dots has been predicted to generate nonlocal pairs of entangled electrons. In order to test this hypothesis, we propose a scheme to transfer the spin state of a split Cooper pair onto the polarization state of a pair of optical photons. We show that the photon pairs produced can be used to violate a Bell inequality, unambiguously demonstrating the entanglement of the split Cooper pairs.

Sensitivity analysis of physiochemical interaction model: which pair ...

African Journals Online (AJOL)

... of two model parameters at a time on the solution trajectory of physiochemical interaction over a time interval. Our aim is to use this powerful mathematical technique to select the important pair of parameters of this physical process which is cost-effective. Keywords: Passivation Rate, Sensitivity Analysis, ODE23, ODE45 ...

Parameter Sensitivity of High–Order Equivalent Circuit Models Of Turbine Generator

Directory of Open Access Journals (Sweden)

T. Niewierowicz–Swiecicka

2010-01-01

Full Text Available This work shows the results of a parametric sensitivity analysis applied to a state–space representation of high–order two–axis equivalent circuits (ECs of a turbo generator (150 MVA, 120 MW, 13.8 kV y 50 Hz. The main purpose of this study is to evaluate each parameter impact on the transient response of the analyzed two–axis models –d–axis ECs with one to five damper branches and q–axis ECs from one to four damper branches–. The parametric sensitivity concept is formulated in a general context and the sensibility function is established from the generator response to a short circuit condition. Results ponder the importance played by each parameter in the model behavior. The algorithms were design within MATLAB® environment. The study gives way to conclusions on electromagnetic aspects of solid rotor synchronous generators that have not been previously studied. The methodology presented here can be applied to any other physical system.

Modulating functions method for parameters estimation in the fifth order KdV equation

KAUST Repository

Asiri, Sharefa M.

2017-07-25

In this work, the modulating functions method is proposed for estimating coefficients in higher-order nonlinear partial differential equation which is the fifth order Kortewegde Vries (KdV) equation. The proposed method transforms the problem into a system of linear algebraic equations of the unknowns. The statistical properties of the modulating functions solution are described in this paper. In addition, guidelines for choosing the number of modulating functions, which is an important design parameter, are provided. The effectiveness and robustness of the proposed method are shown through numerical simulations in both noise-free and noisy cases.

Higher Order QCD Radiation in Top Pair Production with the CMS Detector

CERN Document Server

Flossdorf, Alexander

2009-01-01

The Large Hadron Collider at CERN will collide protons with a centre-of-mass energy of up to √s = 14TeV, thereby offering the opportunity to explore a wide range of physics topics. In this thesis the effects of QCD radiation in top pair events are examined. Due to the large top mass, top pairs are well suited for an investigation of gluon emissions. An extensive study comparing different radiation models implemented in Monte Carlo event generators is presented. The transverse momentum distribution of the $t\\bar{t}$ system is rather sensitive to radiation influences and therefore analysed in detail. As hard emissions can be associated with jets, a thorough investigation of these jets is performed. The transverse momentum of hard jets and the rapidity distribution of the hardest jet in the $t\\bar{t}$ rest frame are examined. Moreover an analysis of samples incorporating different radiation models after the full CMS detector simulation is presented, studying the same observables as on generator level. The pote...

Systematic expansion in the order parameter for replica theory of the dynamical glass transition.

Science.gov (United States)

Jacquin, Hugo; Zamponi, Francesco

2013-03-28

It has been shown recently that predictions from mode-coupling theory for the glass transition of hard-spheres become increasingly bad when dimensionality increases, whereas replica theory predicts a correct scaling. Nevertheless if one focuses on the regime around the dynamical transition in three dimensions, mode-coupling results are far more convincing than replica theory predictions. It seems thus necessary to reconcile the two theoretic approaches in order to obtain a theory that interpolates between low-dimensional, mode-coupling results, and "mean-field" results from replica theory. Even though quantitative results for the dynamical transition issued from replica theory are not accurate in low dimensions, two different approximation schemes--small cage expansion and replicated hyper-netted-chain (RHNC)--provide the correct qualitative picture for the transition, namely, a discontinuous jump of a static order parameter from zero to a finite value. The purpose of this work is to develop a systematic expansion around the RHNC result in powers of the static order parameter, and to calculate the first correction in this expansion. Interestingly, this correction involves the static three-body correlations of the liquid. More importantly, we separately demonstrate that higher order terms in the expansion are quantitatively relevant at the transition, and that the usual mode-coupling kernel, involving two-body direct correlation functions of the liquid, cannot be recovered from static computations.

Orientationally ordered phase produced by fully antinematic interactions: A simulation study

Science.gov (United States)

Romano, Silvano; de Matteis, Giovanni

2011-07-01

We consider here a classical model, consisting of D2h symmetric particles, whose centers of mass are associated with a three-dimensional simple-cubic lattice; the pair potential is isotropic in orientation space, and restricted to nearest neighbors. Two orthonormal triads define orientations of a pair of interacting particles; the simplest potential models proposed in the literature can be written as a linear combination involving the squares of the scalar products between corresponding unit vectors only, thus depending on three parameters, and making the interaction model rather versatile. A coupling constant with negative sign tends to keep the two interacting unit vectors parallel to each other, whereas a positive sign tends to keep them mutually orthogonal (antinematic coupling). We address here a special, extreme case of the above family, involving only antinematic couplings: more precisely, three antinematic terms whose coefficients are set to a common positive value (hence the name PPP model). The model under investigation produces a doubly degenerate pair ground state; the nearest-neighbor range of the interaction and the bipartite character of the lattice can propagate the pair ground state and increase the overall degeneracy, but without producing frustration. The model was investigated by a simplified molecular field treatment as well as by Monte Carlo simulation, whose results suggested a second-order transition to a low-temperature biaxially ordered phase; ground-state configurations producing orientational order have been selected by thermal fluctuations. The molecular field treatment also predicted a continuous transition, and was found to overestimate the transition temperature by a factor 2.

Detecting nonlocal Cooper pair entanglement by optical Bell inequality violation

OpenAIRE

Nigg, Simon E.; Tiwari, Rakesh P.; Walter, Stefan; Schmidt, Thomas L.

2014-01-01

Based on the Bardeen Cooper Schrieffer (BCS) theory of superconductivity, the coherent splitting of Cooper pairs from a superconductor to two spatially separated quantum dots has been predicted to generate nonlocal pairs of entangled electrons. In order to test this hypothesis, we propose a scheme to transfer the spin state of a split Cooper pair onto the polarization state of a pair of optical photons. We show that the produced photon pairs can be used to violate a Bell inequality, unambiguo...

From bare to renormalized order parameter in gauge space: Structure and reactions

Science.gov (United States)

Potel, G.; Idini, A.; Barranco, F.; Vigezzi, E.; Broglia, R. A.

2017-09-01

It is not physically obvious why one can calculate with similar accuracy, as compared to the experimental data, the absolute cross section associated with two-nucleon transfer processes between members of pairing rotational bands, making use of simple BCS (constant matrix elements) or of many-body [Nambu-Gorkov (NG), nuclear field theory (NFT)] spectroscopic amplitudes. Restoration of spontaneous symmetry breaking and associated emergent generalized rigidity in gauge space provides the answer and points to a new emergence: A physical sum rule resulting from the intertwining of structure and reaction processes, closely connected with the central role induced pairing interaction plays in structure, together with the fact that successive transfer dominates Cooper pair tunneling.

Separable pairing force for relativistic quasiparticle random-phase approximation

International Nuclear Information System (INIS)

Tian Yuan; Ma Zhongyu; Ring, Peter

2009-01-01

We have introduced a separable pairing force, which was adjusted to reproduce the pairing properties of the Gogny force in nuclear matter. This separable pairing force is able to describe in relativistic Hartree-Bogoliubov (RHB) calculations the pairing properties in the ground state of finite nuclei on almost the same footing as the original Gogny interaction. In this work we investigate excited states using the Relativistic Quasiparticle Random-Phase Approximation (RQRPA) with the same separable pairing force. For consistency the Goldstone modes and the convergence with various cutoff parameters in this version of RQRPA are studied. The first excited 2 + states for the chain of Sn isotopes with Z=50 and the chain of isotones with N=82 isotones are calculated in RQRPA together with the 3 - states of Sn isotopes. By comparing our results with experimental data and with the results of the original Gogny force we find that this simple separable pairing interaction is very successful in depicting the pairing properties of vibrational excitations.

Top quark pair production beyond NNLO

Energy Technology Data Exchange (ETDEWEB)

Muselli, Claudio [TIF Lab, Dipartimento di Fisica, Università di Milano, and INFN - Sezione di Milano,Via Celoria 16, I-20133 Milano (Italy); Bonvini, Marco [Rudolf Peierls Centre for Theoretical Physics, University of Oxford,1 Keble Road, OX1 3NP, Oxford (United Kingdom); Forte, Stefano [TIF Lab, Dipartimento di Fisica, Università di Milano, and INFN - Sezione di Milano,Via Celoria 16, I-20133 Milano (Italy); Marzani, Simone [Center for Theoretical Physics, Massachusetts Institute of Technology,77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Ridolfi, Giovanni [Dipartimento di Fisica, Università di Genova and INFN - Sezione di Genova,Via Dodecaneso 33, I-16146 Genova (Italy)

2015-08-17

We construct an approximate expression for the total cross section for the production of a heavy quark-antiquark pair in hadronic collisions at next-to-next-to-next-to-leading order (N{sup 3}LO) in α{sub s}. We use a technique which exploits the analyticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummations, previously introduced and used in the case of Higgs production. We validate our method by comparing to available exact results up to NNLO. We find that N{sup 3}LO corrections increase the predicted top pair cross section at the LHC by about 4% over the NNLO.

Top quark pair production beyond NNLO

International Nuclear Information System (INIS)

Muselli, Claudio; Bonvini, Marco; Forte, Stefano; Marzani, Simone; Ridolfi, Giovanni

2015-01-01

We construct an approximate expression for the total cross section for the production of a heavy quark-antiquark pair in hadronic collisions at next-to-next-to-next-to-leading order (N 3 LO) in α s . We use a technique which exploits the analyticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummations, previously introduced and used in the case of Higgs production. We validate our method by comparing to available exact results up to NNLO. We find that N 3 LO corrections increase the predicted top pair cross section at the LHC by about 4% over the NNLO.

Macroscopically constrained Wang-Landau method for systems with multiple order parameters and its application to drawing complex phase diagrams

Science.gov (United States)

Chan, C. H.; Brown, G.; Rikvold, P. A.

2017-05-01

A generalized approach to Wang-Landau simulations, macroscopically constrained Wang-Landau, is proposed to simulate the density of states of a system with multiple macroscopic order parameters. The method breaks a multidimensional random-walk process in phase space into many separate, one-dimensional random-walk processes in well-defined subspaces. Each of these random walks is constrained to a different set of values of the macroscopic order parameters. When the multivariable density of states is obtained for one set of values of fieldlike model parameters, the density of states for any other values of these parameters can be obtained by a simple transformation of the total system energy. All thermodynamic quantities of the system can then be rapidly calculated at any point in the phase diagram. We demonstrate how to use the multivariable density of states to draw the phase diagram, as well as order-parameter probability distributions at specific phase points, for a model spin-crossover material: an antiferromagnetic Ising model with ferromagnetic long-range interactions. The fieldlike parameters in this model are an effective magnetic field and the strength of the long-range interaction.

Defect-antidefect pair production via field oscillations

International Nuclear Information System (INIS)

Digal, S.; Sengupta, S.; Srivastava, A.M.

1997-01-01

We show that the mechanism of vortex-antivortex pair production via field oscillations, earlier proposed by two of us for systems with first order transitions in the presence of explicit symmetry breaking, is in fact generally applicable. We further argue that this mechanism applies to all sorts of topological defects (e.g., strings, monopoles, textures) and for second order transitions as well (involving quench from high temperature). We also show this explicitly by numerically simulating the production of vortex-antivortex pairs by the decay of bubble walls for a U(1) global theory in the absence of any explicit symmetry breaking. copyright 1997 The American Physical Society

The high temperature superconductor YBa₂Cu₃O_7-δ: symmetry of the order parameter, and gradiometers for biomagnetic applications

Energy Technology Data Exchange (ETDEWEB)

Kouznetsov, Konstantin Alexander [Univ. of California, Berkeley, CA (US). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

1999-12-01

The cuprate YBa₂Cu₃O_7-δ is the material that drives the majority of the technological applications of high transition temperature (T_c) superconductors, particularly in the area of superconducting electronics. Despite the widespread use of high-T_c superconducting materials in a variety of applications, the nature of the superconducting state in these materials remains unknown since their discovery more than a decade ago. Many properties of the high-T_c superconductors are determined by their order parameter, which is a wavefunction describing the superconducting condensate. The symmetry of the order parameter in cuprates has been the subject of intensive investigation, leading to conflicting sets of results. Some experiments supported conventional, s-wave symmetry of the order parameter, while others indicated an unconventional, d-wave symmetry. The first part of this thesis is an experimental study of the symmetry of the order parameter in YBa₂Cu₃O_7-δ. A new class of phase sensitive experiments is described that involve Josephson tunneling along the c-axis of twinned crystals of YBa₂Cu₃O_7-δ. These experiments showed that an s-wave component must reverse sign across the twin boundary, providing direct evidence for a mixed, s+d symmetry of the order parameter in YBa₂Cu₃O_7-δ, and thereby reconciling two conflicting sets of previous findings and establishing the dominant d-wave pairing symmetry. The second part of the thesis focuses on practical applications of YBa₂Cu₃O_7-δ in superconducting electronics. The authors introduce a novel Superconducting Quantum Interference Device (SQUID) gradiometer. The principle of operation of these long baseline high-T{sub c} SQUID gradiometers is based on the inductive coupling of the input coil of a planar flux transformer to the

Nonlinear electrostatic structures in homogeneous and inhomogeneous pair-ion plasmas

International Nuclear Information System (INIS)

Mahmood, S.; Ur-Rehman, H.; Shah, A.; Haque, Q.

2012-01-01

The nonlinear electrostatic structures such as solitons, shocks were studied in homogeneous, unmagnetized pair-ion plasma. The dissipation in the system was taken through kinematic viscosities of both pair-ion species. The one dimensional (Korteweg-de Vries-Burgers) KdVB equation was derived using reductive perturbation method. The analytical solution of KdVB equation was obtained using tanh method. It was found that solitons and monotonic shocks structures were formed in such type of plasmas depending on the value of dissipation in the system. Both compressive and refractive structures of solitons and monotonic shocks were obtained depending on the temperatures of negative and positive ions. The oscillatory shock structures in pair-ion plasmas were also obtained and its necessary conditions of formation were discussed. The acoustic solitons were also investigated in inhomogeneous unmagnetized pair-ion plasmas. The Korteweg-de Vries (KdV) like equation with an additional term due to density gradients was obtained by employing the reductive perturbation technique. It was found that amplitude of both compressive and refractive solitons was found to be enhanced as the density gradient parameter was increased. The Landau damping rates of electrostatic ion waves were studied for non-Maxwellian or Lorentzian pair-ion plasmas. The Val sov equation was solved analytically for weak damping effects in pair-ion plasma. It was found that Landau damping rate of ion plasma wave was increased in Lorentzian case in comparison with Maxwellian pair-ion plasmas. The numerical results were obtained by taking into account the parameters of pair-ion plasmas produced in laboratory experiments in Japan. (orig./A.B.)

Pair creation, motion, and annihilation of topological defects in two-dimensional nematic liquid crystals

Science.gov (United States)

Cortese, Dario; Eggers, Jens; Liverpool, Tanniemola B.

2018-02-01

We present a framework for the study of disclinations in two-dimensional active nematic liquid crystals and topological defects in general. The order tensor formalism is used to calculate exact multiparticle solutions of the linearized static equations inside a planar uniformly aligned state so that the total charge has to vanish. Topological charge conservation then requires that there is always an equal number of q =1 /2 and q =-1 /2 charges. Starting from a set of hydrodynamic equations, we derive a low-dimensional dynamical system for the parameters of the static solutions, which describes the motion of a half-disclination pair or of several pairs. Within this formalism, we model defect production and annihilation, as observed in experiments. Our dynamics also provide an estimate for the critical density at which production and annihilation rates are balanced.

Hadronic production of massive lepton pairs

International Nuclear Information System (INIS)

Berger, E.L.

1982-12-01

A review is presented of recent experimental and theoretical progress in studies of the production of massive lepton pairs in hadronic collisions. I begin with the classical Drell-Yan annihilation model and its predictions. Subsequently, I discuss deviations from scaling, the status of the proofs of factorization in the parton model, higher-order terms in the perturbative QCD expansion, the discrepancy between measured and predicted yields (K factor), high-twist terms, soft gluon effects, transverse-momentum distributions, implications for weak vector boson (W +- and Z 0 ) yields and production properties, nuclear A dependence effects, correlations of the lepton pair with hadrons in the final state, and angular distributions in the lepton-pair rest frame

Coherent pair creation from beam-beam interaction

International Nuclear Information System (INIS)

Chen, Pisin.

1989-09-01

It has recently been recognized that in future linear colliders, there is a finite probability that the beamstrahlung photons will turn into e + e - pairs induced by the same beam-beam field, and this would potentially cause background problems. In this paper, we first review the probability of such a coherent pair creation process. It is seen that the constraint on the beamstrahlung parameter, Υ, is tight of these coherent pairs to be totally suppressed. We then point out that there exists a minimum energy for the pair-created particles, which scales as ∼1/5Υ. When combining this condition with the deflection angle for the low-energy particles, the constraint on the allowable Υ value is much relaxed. Finally, we calculate the effective cross section for producing the weak bosons by the low-energy e + e - pairs. It is shown that these cross sections are substantial for Υ > 1. We suggest that this effect can help to autoscan the particle spectrum in the high energy frontier. 10 refs., 2 figs

Dimensional study of the caging order parameter at the glass transition.

Science.gov (United States)

Charbonneau, Patrick; Ikeda, Atsushi; Parisi, Giorgio; Zamponi, Francesco

2012-08-28

The glass problem is notoriously hard and controversial. Even at the mean-field level, little is agreed upon regarding why a fluid becomes sluggish while exhibiting but unremarkable structural changes. It is clear, however, that the process involves self-caging, which provides an order parameter for the transition. It is also broadly assumed that this cage should have a gaussian shape in the mean-field limit. Here we show that this ansatz does not hold. By performing simulations as a function of spatial dimension d, we find the cage to keep a nontrivial form. Quantitative mean-field descriptions of the glass transition, such as mode-coupling theory, density functional theory, and replica theory, all miss this crucial element. Although the mean-field random first-order transition scenario of the glass transition is qualitatively supported here and non-mean-field corrections are found to remain small on decreasing d, reconsideration of its implementation is needed for it to result in a coherent description of experimental observations.

Higher order QCD radiation in top pair production with the CMS detector

International Nuclear Information System (INIS)

Flossdorf, Alexander

2009-10-01

The Large Hadron Collider at CERN will collide protons with a centre-of-mass energy of up to √(s)=14 TeV, thereby offering the opportunity to explore a wide range of physics topics. In this thesis the effects of QCD radiation in top pair events are examined. Due to the large top mass, top pairs are well suited for an investigation of gluon emissions. An extensive study comparing different radiation models implemented in Monte Carlo event generators is presented. The transverse momentum distribution of the t anti t system is rather sensitive to radiation influences and therefore analysed in detail. As hard emissions can be associated with jets, a thorough investigation of these jets is performed. The transverse momentum of hard jets and the rapidity distribution of the hardest jet in the t anti t rest frame are examined. Moreover an analysis of samples incorporating different radiation models after the full CMS detector simulation is presented, studying the same observables as on generator level. The potential of the CMS experiment to distinguish between different models is estimated and a method to obtain the underlying transverse momentum distribution of the t anti t system is described. (orig.)

Quantum correction and ordering parameter for systems connected by a general point canonical transformation

International Nuclear Information System (INIS)

Yeon, Kyu Hwang; Hong, Suc Kyoung; Um, Chung In; George, Thomas F.

2006-01-01

With quantum operators corresponding to functions of the canonical variables, Schroedinger equations are constructed for systems corresponding to classical systems connected by a general point canonical transformation. Using the operator connecting quantum states between systems before and after the transformation, the quantum correction term and ordering parameter are obtained

Strain and order-parameter coupling in Ni-Mn-Ga Heusler alloys from resonant ultrasound spectroscopy

Science.gov (United States)

Salazar Mejía, C.; Born, N.-O.; Schiemer, J. A.; Felser, C.; Carpenter, M. A.; Nicklas, M.

2018-03-01

Resonant ultrasound spectroscopy and magnetic susceptibility experiments have been used to characterize strain coupling phenomena associated with structural and magnetic properties of the shape-memory Heusler alloy series Ni50 +xMn25 -xGa25 (x =0 , 2.5, 5.0, and 7.5). All samples exhibit a martensitic transformation at temperature TM and ferromagnetic ordering at temperature TC, while the pure end member (x =0 ) also has a premartensitic transition at TP M, giving four different scenarios: TC>TP M>TM,TC>TM without premartensitic transition, TC≈TM , and TCorder parameters relating to magnetic ordering, a soft mode, and the electronic instability responsible for the large strains typical of martensitic transitions. Linear-quadratic or biquadratic coupling between these order parameters, either directly or indirectly via the common strains, is then used to explain the stabilities of the different structures. Acoustic losses are attributed to critical slowing down at the premartensite transition, to the mobility of interphases between coexisting phases at the martensitic transition, and to mobility of some aspect of the twin walls under applied stress down to the lowest temperatures at which measurements were made.

Effect of single interstitial impurity in iron-based superconductors with sign-changed s-wave pairing symmetry

Energy Technology Data Exchange (ETDEWEB)

Yu, Xiang-Long, E-mail: xlyu@theory.issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Liu, Da-Yong; Quan, Ya-Min; Zheng, Xiao-Jun [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Zou, Liang-Jian, E-mail: zou@theory.issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Department of Physics, University of Science and Technology of China, Hefei 230026 (China)

2015-12-15

Highlights: • Effects of single interstitial impurity are studied in iron-based superconductors. • Bound states within the superconducting gap can be induced. • The interstitial impurity can induce a π phase shift of pairing order parameter. • For strong magnetic scattering the bound-state peak can appear at the Fermi level. - Abstract: We employ the self-consistent Bogoliubov-de Gennes (BdG) formulation to investigate the effect of single interstitial nonmagnetic/magnetic impurity in iron-based superconductors with s ± -wave pairing symmetry. We find that both the nonmagnetic and magnetic impurities can induce bound states within the superconducting (SC) gap and a π phase shift of SC order parameter at the impurity site. However, different from the interstitial-nonmagnetic-impurity case characterized by two symmetric peaks with respect to zero energy, the interstitial magnetic one only induces single bound-state peak. In the strong scattering regime this peak can appear at the Fermi level, which has been observed in the recent scanning tunneling microscope (STM) experiment of Fe(Te,Se) superconductor with interstitial Fe impurities (Yin et al. 2015 [44]). This novel single in-gap peak feature also distinguishes the interstitial case from the substitutional one with two peaks. These results provide important information for comparing the different impurity effects in the iron-based superconductors.

Baryonic 3P2-dominant superfluidity under combined pion condensation with Δ isobar. II). Properties of pairing interaction and numerical results

International Nuclear Information System (INIS)

Tamagaki, Ryozo

2007-01-01

According to the formulation developed in I, we calculate energy gaps of the baryonic 3 P 2 -dominant superfluidity under the combined pion condensation with Δ-mixing at moderately high density in neutron star interior. Adopting a baryon-baryon potential extended from a 'root' NN potential to be workable in the N+Δ space, we obtain the concrete form of the pairing interaction matrix elements between the quasi-baryon pairs, which constitute a two-dimensional angular-momentum stretched state and a charge triplet. With use of OPEG-B as a 'root' NN potential and an available set of the parameters representing the combined pion condensation, we study the properties of two-dimensional pairing potentials and the matrix elements of pairing interaction. We find that the strong attraction of pairing interaction for the quasi-neutron pairs is brought about by the spin-orbit potential and the spin- and isospin-dependent core terms of the central potential, whose effects are enhanced due to the pion condensation. The quasi-neutron pair plays a decisive role to bring about meaningful energy gaps, while the coupling between different quasi-baryon pairs plays no important role, as a consequence of a unique feature of the combined pion condensation we adopt. We numerically solve the energy gap equation for baryon density of (2-6) times the nuclear density and clarify substantial aspects of resulting superfluid energy gaps, and discuss related problems by taking into account possible change in the factors affecting the energy gaps, such as baryon-baryon potentials, some of the pion condensation parameters and an effective mass of the quasi-particle. Standing on these results, we can say that the 3 P 2 -dominant superfluid is realized with the critical temperatures T c of the order of 10 9 K, equivalent to the energy gaps of the order of 0.1 MeV, under the combined pion condensation in neutron star matter. The key point of the recognition lies in the aspects that the �

Baryonic 3 P2-Dominant Superfluidity under Combined Pion Condensation with Δ Isobar. II --- Properties of Pairing Interaction and Numerical Results ---

Science.gov (United States)

Tamagaki, R.; Takatsuka, T.

2007-05-01

According to the formulation developed in I, we calculate energy gaps of the baryonic (3) P_2-dominant superfluidity under the combined pion condensation with Delta-mixing at moderately high density in neutron star interior. Adopting a baryon-baryon potential extended from a ``root" NN potential to be workable in the N + Delta space, we obtain the concrete form of the pairing interaction matrix elements between the quasi-baryon pairs, which constitute a two-dimensional angular-momentum stretched state and a charge triplet. With use of OPEG-B as a ``root" NN potential and an available set of the parameters representing the combined pion condensation, we study the properties of two-dimensional pairing potentials and the matrix elements of pairing interaction. We find that the strong attraction of pairing interaction for the quasi-neutron pairs is brought about by the spin-orbit potential and the spin- and isospin-dependent core terms of the central potential, whose effects are enhanced due to the pion condensation. The quasi-neutron pair plays a decisive role to bring about meaningful energy gaps, while the coupling between different quasi-baryon pairs plays no important role, as a consequence of a unique feature of the combined pion condensation we adopt. We numerically solve the energy gap equation for baryon density of (2-6) times the nuclear density and clarify substantial aspects of resulting superfluid energy gaps, and discuss related problems by taking into account possible change in the factors affecting the energy gaps, such as baryon-baryon potentials, some of the pion condensation parameters and an effective mass of the quasi-particle. Standing on these results, we can say that the (3) P_2-dominant superfluid is realized with the critical temperatures T_c of the order of 10(9) K, equivalent to the energy gaps of the order of 0.1 MeV, under the combined pion condensation in neutron star matter. The key point of the recognition lies in the aspects that the

Full one-loop QCD and electroweak corrections to sfermion pair production in γγ collisions

International Nuclear Information System (INIS)

Xing Lirong; Zhang Renyou; Jiang Yi; Han Liang; Li Gang; Ma Wengan

2005-01-01

We have calculated the full one-loop electroweak (EW) and QCD corrections to the third generation scalar-fermion pair production processes e + e - →γγ→f i -tildef i -tilde(f=t,b,τ) at an electron-positron linear collider(LC) in the minimal supersymmetric standard model (MSSM). We analyze the dependence of the radiative corrections on the parameters such as the colliding energy √(s-circumflex) and the SUSY fundamental parameters A f , tanβ, μ, M SUSY and so forth. The numerical results show that the EW corrections to the squark-, stau-pair production processes and QCD corrections to the squark-pair production processes give substantial contributions in some parameter space. The EW relative corrections to squark-pair production processes can be comparable with QCD corrections at high energies. Therefore, these EW and QCD corrections cannot be neglected in precise measurement of sfermion pair productions via γγ collision at future linear colliders

Reduction of the chiral order parameter by a nuclear medium

International Nuclear Information System (INIS)

Kienle, P.; Yamazaki, Toshimizu

2001-01-01

We propose a model independent procedure to deduce from the 1s-binding energy of heavy, neutron rich pionic atoms, the isovector scattering length b 1 of the pion nucleus interaction. It is related to the pion decay constant f π , the order parameter of spontaneous chiral symmetry breaking and thus to the value of the chiral quark condensate. Based on the results with pionic 205 Pb, we find with the assertion that only the isovector part of the pion-nucleus interaction be modified by a QCD effect, a reduction of the quark condensate by 30% in a 205 Pb nucleus. Forthcoming experiments to measure pionic 1s-binding energies in Sn-isotopes, including isotope shifts, will yield decisive information on the quark condensate without assertion. (orig.)

Multi-pair states in electron–positron pair creation

Directory of Open Access Journals (Sweden)

Anton Wöllert

2016-09-01

Full Text Available Ultra strong electromagnetic fields can lead to spontaneous creation of single or multiple electron–positron pairs. A quantum field theoretical treatment of the pair creation process combined with numerical methods provides a description of the fermionic quantum field state, from which all observables of the multiple electron–positron pairs can be inferred. This allows to study the complex multi-particle dynamics of electron–positron pair creation in-depth, including multi-pair statistics as well as momentum distributions and spin. To illustrate the potential benefit of this approach, it is applied to the intermediate regime of pair creation between nonperturbative Schwinger pair creation and perturbative multiphoton pair creation where the creation of multi-pair states becomes nonnegligible but cascades do not yet set in. Furthermore, it is demonstrated how spin and helicity of the created electrons and positrons are affected by the polarization of the counterpropagating laser fields, which induce the creation of electron–positron pairs.

Multi-pair states in electron–positron pair creation

Energy Technology Data Exchange (ETDEWEB)

Wöllert, Anton, E-mail: woellert@mpi-hd.mpg.de; Bauke, Heiko, E-mail: heiko.bauke@mpi-hd.mpg.de; Keitel, Christoph H.

2016-09-10

Ultra strong electromagnetic fields can lead to spontaneous creation of single or multiple electron–positron pairs. A quantum field theoretical treatment of the pair creation process combined with numerical methods provides a description of the fermionic quantum field state, from which all observables of the multiple electron–positron pairs can be inferred. This allows to study the complex multi-particle dynamics of electron–positron pair creation in-depth, including multi-pair statistics as well as momentum distributions and spin. To illustrate the potential benefit of this approach, it is applied to the intermediate regime of pair creation between nonperturbative Schwinger pair creation and perturbative multiphoton pair creation where the creation of multi-pair states becomes nonnegligible but cascades do not yet set in. Furthermore, it is demonstrated how spin and helicity of the created electrons and positrons are affected by the polarization of the counterpropagating laser fields, which induce the creation of electron–positron pairs.

Multi-pair states in electron–positron pair creation

International Nuclear Information System (INIS)

Wöllert, Anton; Bauke, Heiko; Keitel, Christoph H.

2016-01-01

Ultra strong electromagnetic fields can lead to spontaneous creation of single or multiple electron–positron pairs. A quantum field theoretical treatment of the pair creation process combined with numerical methods provides a description of the fermionic quantum field state, from which all observables of the multiple electron–positron pairs can be inferred. This allows to study the complex multi-particle dynamics of electron–positron pair creation in-depth, including multi-pair statistics as well as momentum distributions and spin. To illustrate the potential benefit of this approach, it is applied to the intermediate regime of pair creation between nonperturbative Schwinger pair creation and perturbative multiphoton pair creation where the creation of multi-pair states becomes nonnegligible but cascades do not yet set in. Furthermore, it is demonstrated how spin and helicity of the created electrons and positrons are affected by the polarization of the counterpropagating laser fields, which induce the creation of electron–positron pairs.

Nonlinear Parameter-Varying AeroServoElastic Reduced Order Model for Aerostructural Sensing and Control, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The overall goal of the project is to develop reliable reduced order modeling technologies to automatically generate nonlinear, parameter-varying (PV),...

Pairing phase transition and thermodynamical quantities in 148,149Sm

International Nuclear Information System (INIS)

Razavi, R.; Behkami, A.N.; Dehghani, V.

2014-01-01

The nuclear level densities and entropies in 148,149 Sm have been calculated in the framework of the superconducting theory that includes modified nuclear pairing gap. For modified pairing gap parameter the smooth transition from the BCS to the Fermi type distributions is used. By applying modified pairing gap, the extracted S-shaped heat capacity as a function of nuclear temperature exhibits a physical and smoother behavior instead of the singular behavior predicted by the BCS equations at critical temperature

Computational studies of a cut-wire pair and combined metamaterials

International Nuclear Information System (INIS)

Nguyen, Thanh Tung; Lievens, Peter; Lee, Young Pak; Vu, Dinh Lam

2011-01-01

The transfer-matrix method and finite-integration simulations show how the transmission properties of combined metamaterials, which consist of metallic cut-wire pairs and continuous wires, are affected by geometric parameters. The corresponding effective permittivity and permeability are retrieved from the complex scattering parameters using the standard retrieval procedure. The electromagnetic properties of the cut-wire pair as well as the left-handed behavior of the combined structure are understood by the effective medium theory. In addition, the dimensional dependence of transmission properties, the shapes of cut-wire pairs and continuous wire, and the impact of dielectric spacer are both examined. Finally, by expanding the results of previous research (Koschny et al 2003 Phys. Rev. Lett. 93 016608), we generalize the transmission picture of combined structures in terms of the correlation between electric and magnetic responses. (review)

Pair q-coherent states and their antibunching effects

International Nuclear Information System (INIS)

Wang Zhongqing; Li Junhong; An Guanglei; Chongqing Univ. of Posts and Telecommunications, Chongqing

2005-01-01

Using the properties of the q-deformed boson creation and annihilation operators and their inverse operators, two kind of q-deformed pair coherent states are introduced. Antibunching effects and correlation properties between two modes in the states are investigated. It is shown that q-deformed pair coherent states exhibit antibunching effects and the photons of the two modes are correlated. These nonclassical effects are influenced by the parameter q. These effects increase when |lnq| increases. (authors)

A comprehensive study on gain stabilization of Er-doped fiber amplifier in C-band with uniform fiber Bragg grating-pair

Science.gov (United States)

Yang, Jiuru; Ma, Yu; OuYang, Yunlun; Liu, Chunyu; Zhang, Jiaxiao

2014-07-01

Fiber grating-pair is one of the efficient methods for gain stabilization of erbium doped fiber amplifier (EDFA) but with a gain-reduction of signals, especially in C-band. In order to overcome it, in this article, we establish a configuration of EDFA based uniform fiber grating-pair and conduct a comprehensive study on gain stabilization by varying the reflectivity, center wavelength and 3dB bandwidth of grating, and by varying the channel number and pump power. The numerical results show that under the optimal parameters of grating the gain stabilization at 1550nm is +/-0.044dB with high gain and large dynamic range.

Top-quark pair production at hadron colliders

Energy Technology Data Exchange (ETDEWEB)

Ahrens, Valentin

2011-12-08

In this thesis we investigate several phenomenologically important properties of top-quark pair production at hadron colliders. We calculate double differential cross sections in two different kinematical setups, pair invariant-mass (PIM) and single-particle inclusive (1PI) kinematics. In pair invariant-mass kinematics we are able to present results for the double differential cross section with respect to the invariant mass of the top-quark pair and the top-quark scattering angle. Working in the threshold region, where the pair invariant mass M is close to the partonic center-of-mass energy {radical}(s), we are able to factorize the partonic cross section into different energy regions. We use renormalization-group (RG) methods to resum large threshold logarithms to next-to-next-to-leading-logarithmic (NNLL) accuracy. On a technical level this is done using effective field theories, such as heavy-quark effective theory (HQET) and soft-collinear effective theory (SCET). The same techniques are applied when working in 1PI kinematics, leading to a calculation of the double differential cross section with respect to transverse-momentum pT and the rapidity of the top quark. We restrict the phase-space such that only soft emission of gluons is possible, and perform a NNLL resummation of threshold logarithms. The obtained analytical expressions enable us to precisely predict several observables, and a substantial part of this thesis is devoted to their detailed phenomenological analysis. Matching our results in the threshold regions to the exact ones at next-to-leading order (NLO) in fixed-order perturbation theory, allows us to make predictions at NLO+NNLL order in RG-improved, and at approximate next-to-next-to-leading order (NNLO) in fixed order perturbation theory. We give numerical results for the invariant mass distribution of the top-quark pair, and for the top-quark transverse-momentum and rapidity spectrum. We predict the total cross section, separately for both

On the motion of non-linear oscillators with a fractional-order restoring force and time variable parameters

International Nuclear Information System (INIS)

Kovacic, Ivana

2009-01-01

An analytical approach to determine the approximate solution for the periodic motion of non-conservative oscillators with a fractional-order restoring force and slowly varying parameters is presented. The solution has the form of the first-order differential equation for the amplitude and phase of motion. The method used is based on the combination of the Krylov-Bogoliubov method with Hamilton's variational principle with the uncommutative rule for the variation of velocity. The conservative systems with slowly varying parameters are also considered. The corresponding adiabatic invariant is obtained. Two examples are given to illustrate derived theoretical results.

String pair production in non homogeneous backgrounds

Energy Technology Data Exchange (ETDEWEB)

Bolognesi, S. [Department of Physics “E. Fermi” University of Pisa, and INFN - Sezione di Pisa,Largo Pontecorvo, 3, Ed. C, 56127 Pisa (Italy); Rabinovici, E. [Racah Institute of Physics, The Hebrew University of Jerusalem,91904 Jerusalem (Israel); Tallarita, G. [Departamento de Ciencias, Facultad de Artes Liberales,Universidad Adolfo Ibáñez, Santiago 7941169 (Chile)

2016-04-28

We consider string pair production in non homogeneous electric backgrounds. We study several particular configurations which can be addressed with the Euclidean world-sheet instanton technique, the analogue of the world-line instanton for particles. In the first case the string is suspended between two D-branes in flat space-time, in the second case the string lives in AdS and terminates on one D-brane (this realizes the holographic Schwinger effect). In some regions of parameter space the result is well approximated by the known analytical formulas, either the particle pair production in non-homogeneous background or the string pair production in homogeneous background. In other cases we see effects which are intrinsically stringy and related to the non-homogeneity of the background. The pair production is enhanced already for particles in time dependent electric field backgrounds. The string nature enhances this even further. For spacial varying electrical background fields the string pair production is less suppressed than the rate of particle pair production. We discuss in some detail how the critical field is affected by the non-homogeneity, for both time and space dependent electric field backgrouds. We also comment on what could be an interesting new prediction for the small field limit. The third case we consider is pair production in holographic confining backgrounds with homogeneous and non-homogeneous fields.

String pair production in non homogeneous backgrounds

International Nuclear Information System (INIS)

Bolognesi, S.; Rabinovici, E.; Tallarita, G.

2016-01-01

We consider string pair production in non homogeneous electric backgrounds. We study several particular configurations which can be addressed with the Euclidean world-sheet instanton technique, the analogue of the world-line instanton for particles. In the first case the string is suspended between two D-branes in flat space-time, in the second case the string lives in AdS and terminates on one D-brane (this realizes the holographic Schwinger effect). In some regions of parameter space the result is well approximated by the known analytical formulas, either the particle pair production in non-homogeneous background or the string pair production in homogeneous background. In other cases we see effects which are intrinsically stringy and related to the non-homogeneity of the background. The pair production is enhanced already for particles in time dependent electric field backgrounds. The string nature enhances this even further. For spacial varying electrical background fields the string pair production is less suppressed than the rate of particle pair production. We discuss in some detail how the critical field is affected by the non-homogeneity, for both time and space dependent electric field backgrouds. We also comment on what could be an interesting new prediction for the small field limit. The third case we consider is pair production in holographic confining backgrounds with homogeneous and non-homogeneous fields.

Nonlinear Parameter-Varying AeroServoElastic Reduced Order Model for Aerostructural Sensing and Control, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The overall goal of the project is to develop reliable reduced order modeling technologies to automatically generate parameter-varying (PV), aeroservoelastic (ASE)...

Off-shell pairing correlations from meson-exchange theory of nuclear forces

International Nuclear Information System (INIS)

Sedrakian, Armen

2003-01-01

We develop a model of off-mass-shell pairing correlations in nuclear systems, which is based on the meson-exchange picture of nuclear interactions. The temporal retardations in the model are generated by the Fock-exchange diagrams. The kernel of the complex gap equation for baryons is related to the in-medium spectral function of mesons, which is evaluated nonperturbatively in the random phase approximation. The model is applied to the low-density neutron matter in neutron star crusts by separating the interaction into a long-range one-pion-exchange component and a short-range component parametrized in terms of Landau Fermi liquid parameters. The resulting Eliashberg-type coupled nonlinear integral equations are solved by an iterative procedure. We find that the self-energies extend to off-shell energies of the order of several tens of MeV. At low energies the damping of the neutron pair correlations due to the coupling to the pionic modes is small, but becomes increasingly important as the energy is increased. We discuss an improved quasiclassical approximation under which the numerical solutions are obtained

Heavy-quark pair production in gluon fusion at next-to-next-to-leading O({alpha}{sup 4}{sub s}) order. One-loop squared contributions

Energy Technology Data Exchange (ETDEWEB)

Kniehl, B.A.; Merebashvili, Z. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Koerner, J.G. [Mainz Univ. (Germany). Inst. fuer Physik; Rogal, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2008-09-15

We calculate the next-to-next-to-leading order O({alpha}{sup 4}{sub s}) one-loop squared corrections to the production of heavy quark pairs in the gluon-gluon fusion process. Together with the previously derived results on the q anti q production channel the results of this paper complete the calculation of the oneloop squared contributions of the next-to-next-to-leading order O({alpha}{sup 4}{sub s}) radiative QCD corrections to the hadroproduction of heavy flavours. Our results, with the full mass dependence retained, are presented in a closed and very compact form, in dimensional regularization. (orig.)

Ponderomotive effects in multiphoton pair production

Science.gov (United States)

Kohlfürst, Christian; Alkofer, Reinhard

2018-02-01

The Dirac-Heisenberg-Wigner formalism is employed to investigate electron-positron pair production in cylindrically symmetric but otherwise spatially inhomogeneous, oscillating electric fields. The oscillation frequencies are hereby tuned to obtain multiphoton pair production in the nonperturbative threshold regime. An effective mass, as well as a trajectory-based semiclassical analysis, is introduced in order to interpret the numerical results for the distribution functions as well as for the particle yields and spectra. The results, including the asymptotic particle spectra, display clear signatures of ponderomotive forces.

Behaviour of the order parameter of the simple magnet in an external field

Directory of Open Access Journals (Sweden)

M.P.Kozlovskii

2005-01-01

Full Text Available The effect of a homogeneous external field on the three-dimensional uniaxial magnet behaviour near the critical point is investigated within the framework of the nonperturbative collective variables method using the ρ4 model. The research is carried out for the low-temperature region. The analytic explicit expressions for the free energy, average spin moment and susceptibility are obtained for weak and strong fields in comparison with the field value belonging to the pseudocritical line. The calculations are performed on the microscopic level without any adjusting parameters. It is established that the long-wave fluctuations of the order parameter play a crucial role in forming a crossover between the temperature-dependence and field-dependence critical behaviour of the system.

Investigation of the paired-gear method in selectivity studies

DEFF Research Database (Denmark)

Sistiaga, Manu; Herrmann, Bent; Larsen, R.B.

2009-01-01

was repeated throughout the eight cases in this investigation. When using the paired-gear method, the distribution of the estimated L50 and SR is wider; the distribution of the estimated split parameter has a higher variability than the true split; the estimated mean L50 and SR can be biased; the estimated...... recommend that the methodology used to obtain selectivity estimates using the paired-gear method be reviewed....

First-order exchange coefficient coupling for simulating surface water-groundwater interactions: Parameter sensitivity and consistency with a physics-based approach

Science.gov (United States)

Ebel, B.A.; Mirus, B.B.; Heppner, C.S.; VanderKwaak, J.E.; Loague, K.

2009-01-01

Distributed hydrologic models capable of simulating fully-coupled surface water and groundwater flow are increasingly used to examine problems in the hydrologic sciences. Several techniques are currently available to couple the surface and subsurface; the two most frequently employed approaches are first-order exchange coefficients (a.k.a., the surface conductance method) and enforced continuity of pressure and flux at the surface-subsurface boundary condition. The effort reported here examines the parameter sensitivity of simulated hydrologic response for the first-order exchange coefficients at a well-characterized field site using the fully coupled Integrated Hydrology Model (InHM). This investigation demonstrates that the first-order exchange coefficients can be selected such that the simulated hydrologic response is insensitive to the parameter choice, while simulation time is considerably reduced. Alternatively, the ability to choose a first-order exchange coefficient that intentionally decouples the surface and subsurface facilitates concept-development simulations to examine real-world situations where the surface-subsurface exchange is impaired. While the parameters comprising the first-order exchange coefficient cannot be directly estimated or measured, the insensitivity of the simulated flow system to these parameters (when chosen appropriately) combined with the ability to mimic actual physical processes suggests that the first-order exchange coefficient approach can be consistent with a physics-based framework. Copyright ?? 2009 John Wiley & Sons, Ltd.

Higgs Boson Pair Production in Gluon Fusion at Next-to-Leading Order with Full Top-Quark Mass Dependence.

Science.gov (United States)

Borowka, S; Greiner, N; Heinrich, G; Jones, S P; Kerner, M; Schlenk, J; Schubert, U; Zirke, T

2016-07-01

We present the calculation of the cross section and invariant mass distribution for Higgs boson pair production in gluon fusion at next-to-leading order (NLO) in QCD. Top-quark masses are fully taken into account throughout the calculation. The virtual two-loop amplitude has been generated using an extension of the program GoSam supplemented with an interface to Reduze for the integral reduction. The occurring integrals have been calculated numerically using the program SecDec. Our results, including the full top-quark mass dependence for the first time, allow us to assess the validity of various approximations proposed in the literature, which we also recalculate. We find substantial deviations between the NLO result and the different approximations, which emphasizes the importance of including the full top-quark mass dependence at NLO.

Lepton pair production at ISR energies and QCD

International Nuclear Information System (INIS)

Altarelli, G.; Martinelli, G.

1985-01-01

Motivated by some recent results from the ISR we have considered all available data on the production of Drell-Yan pairs by high energy proton beams. We show that the lepton pair cross sections and qsub(T) distributions are correctly described by QCD using the known distributions of partons in the proton and acceptable values of the QCD scale Λ. No other free parameter is required. Within the accuracy of the data no appreciable intrinsic transverse momentum is needed. (orig.)

Analytical Expressions for the Mixed-Order Kinetics Parameters of TL Glow Peaks Based on the two Heating Rates Method.

Science.gov (United States)

Maghrabi, Mufeed; Al-Abdullah, Tariq; Khattari, Ziad

2018-03-24

The two heating rates method (originally developed for first-order glow peaks) was used for the first time to evaluate the activation energy (E) from glow peaks obeying mixed-order (MO) kinetics. The derived expression for E has an insignificant additional term (on the scale of a few meV) when compared with the first-order case. Hence, the original expression for E using the two heating rates method can be used with excellent accuracy in the case of MO glow peaks. In addition, we derived a simple analytical expression for the MO parameter. The present procedure has the advantage that the MO parameter can now be evaluated using analytical expression instead of using the graphical representation between the geometrical factor and the MO parameter as given by the existing peak shape methods. The applicability of the derived expressions for real samples was demonstrated for the glow curve of Li 2 B 4 O 7 :Mn single crystal. The obtained parameters compare very well with those obtained by glow curve fitting and with the available published data.

Sexually dimorphic activation of dopaminergic areas depends on affiliation during courtship and pair formation

Directory of Open Access Journals (Sweden)

Mai eIwasaki

2014-06-01

Full Text Available For many species, dyadic interaction during courtship and pair bonding engage intense emotional states that control approach or avoidance behavior. Previous studies have shown that one component of a common social brain network (SBN, dopaminergic areas, are highly engaged during male songbird courtship of females. We tested whether the level of activity in dopaminergic systems of both females and males during courtship is related to their level of affiliation. In order to objectively quantify affiliative behaviors, we developed a system for tracking the position of both birds during free interaction sessions. During a third successive daily interaction session, there was a range of levels of affiliation among bird pairs, as quantified by several position and movement parameters. Because both positive and negative social interactions were present, we chose to characterize affiliation strength by pair valence. As a potential neural system involved in regulating pair valence, the level of activity of the dopaminergic group A11 (within the central gray was selectively reduced in females of positive valence pairs. Further, activation of non-dopaminergic neurons in VTA was negatively related to valence, with this relationship strongest in ventral VTA of females. Together, these results suggest that inhibition of fear or avoidance networks may be associated with development of close affiliation, and highlight the importance of negative as well as positive emotional states in the process of courtship, and in development of long-lasting social bonds.

Determination of constants of factorized pairing force from conservation laws

International Nuclear Information System (INIS)

Voronkov, Yu.P.; Mikhajlov, V.M.

1975-01-01

The constants of a factorized interaction in the particle-particle channel are evaluated on the basis of average field parameters and Cooper pairing. The relations between the constants of multipole particle-particle forces are derived for the spherical nuclei. The constants of the quadrupole pairing are obtained for deformed nuclei from the angular momentum conservation law. The calculated constants are compared with empiricalones

PAIR PRODUCTION IN LOW-LUMINOSITY GALACTIC NUCLEI

International Nuclear Information System (INIS)

Moscibrodzka, M.; Gammie, C. F.; Dolence, J. C.; Shiokawa, H.

2011-01-01

Electron-positron pairs may be produced near accreting black holes by a variety of physical processes, and the resulting pair plasma may be accelerated and collimated into a relativistic jet. Here, we use a self-consistent dynamical and radiative model to investigate pair production by γγ collisions in weakly radiative accretion flows around a black hole of mass M and accretion rate M-dot . Our flow model is drawn from general relativistic magnetohydrodynamic simulations, and our radiation field is computed by a Monte Carlo transport scheme assuming the electron distribution function is thermal. We argue that the pair production rate scales as r -6 M -1 M-dot 6 . We confirm this numerically and calibrate the scaling relation. This relation is self-consistent in a wedge in M, M-dot parameter space. If M-dot is too low the implied pair density over the poles of the black hole is below the Goldreich-Julian density and γγ pair production is relatively unimportant; if M-dot is too high the models are radiatively efficient. We also argue that for a power-law spectrum the pair production rate should scale with the observables L X ≡ X-ray luminosity and M as L 2 X M -4 . We confirm this numerically and argue that this relation likely holds even for radiatively efficient flows. The pair production rates are sensitive to black hole spin and to the ion-electron temperature ratio which are fixed in this exploratory calculation. We finish with a brief discussion of the implications for Sgr A* and M87.

Deterministic flows of order-parameters in stochastic processes of quantum Monte Carlo method

International Nuclear Information System (INIS)

Inoue, Jun-ichi

2010-01-01

In terms of the stochastic process of quantum-mechanical version of Markov chain Monte Carlo method (the MCMC), we analytically derive macroscopically deterministic flow equations of order parameters such as spontaneous magnetization in infinite-range (d(= ∞)-dimensional) quantum spin systems. By means of the Trotter decomposition, we consider the transition probability of Glauber-type dynamics of microscopic states for the corresponding (d + 1)-dimensional classical system. Under the static approximation, differential equations with respect to macroscopic order parameters are explicitly obtained from the master equation that describes the microscopic-law. In the steady state, we show that the equations are identical to the saddle point equations for the equilibrium state of the same system. The equation for the dynamical Ising model is recovered in the classical limit. We also check the validity of the static approximation by making use of computer simulations for finite size systems and discuss several possible extensions of our approach to disordered spin systems for statistical-mechanical informatics. Especially, we shall use our procedure to evaluate the decoding process of Bayesian image restoration. With the assistance of the concept of dynamical replica theory (the DRT), we derive the zero-temperature flow equation of image restoration measure showing some 'non-monotonic' behaviour in its time evolution.

Differential bremsstrahlung and pair production cross sections at high energies

International Nuclear Information System (INIS)

Olsen, Haakon A.

2003-01-01

Detailed differential cross sections for high energy bremsstrahlung and pair production are derived with specific attention to the differences between the two processes, which are considerable. For the integrated cross sections, which are the only cross sections specifically known until now, the final state integration theorem guarantees that the exact cross section formulas can be exchanged between bremsstrahlung and pair production by the same substitution rules as for the Born-approximation Bethe-Heitler cross sections, for any amount of atomic screening. In fact the theorem states that the Coulomb corrections to the integrated bremsstrahlung and pair production cross sections are identical for any amount of screening. The analysis of the basic differential cross sections leads to fundamental physical differences between bremsstrahlung and pair production. Coulomb corrections occur for pair production in the strong electric field of the atom for 'large' momentum transfer of the order of mc. For bremsstrahlung, on the other hand, the Coulomb corrections take place at a 'large' distance from the atom of the order of ((ℎ/2π)/mc)ε, with a 'small' momentum transfer mc/ε, where ε is the initial electron energy in units of mc 2 . And the Coulomb corrections can be large, of the order of larger than (Z/137) 2 , which is considerably larger than the integrated cross section corrections

Processes of arbitrary order in quantum electrodynamics with a pair-creating external field

International Nuclear Information System (INIS)

Gitman, D.M.

1977-01-01

Dyson's perturbation theory analogue for quantum electrodynamical processes with arbitrary initial and final states in an external field creating pairs is discussed. The interaction with the field is taken into account exactly. The possibility of using Feynman diagrams, together with modified correspondence rules, for the representation of the above mentioned processes is demonstrated. (author)

Study of correlations between photoproduced pairs of charmed particles at Experiment E831/FOCUS

Energy Technology Data Exchange (ETDEWEB)

Castromonte Flores, Cesar Manuel [Brazilian Center for Physics Research, Rio de Janeiro (Brazil)

2008-08-01

The authors present the study of the charm-pair correlations produced in photon-nucleon interactions at $\\langle$E_γ$\\rangle$ = 175 GeV/c, by the Fermilab fixed target experiment E831/FOCUS. The E831/FOCUS experiment produced and reconstructed over one million charm particles. This high statistics allows the reconstruction of more than 7000 charm-pair mesons D$\\bar{D}$, 10 times the statistic of former experiments, and also allows to get, for the first time, about 600 totally reconstructed charm-pairs in the DD_s and DΛ_c channels. They were able to study, with some detail, the kinematical correlations between the charm and anticharm particle forming a pair, in the square transverse momentum (p_T²), azimuthal angle difference (ΔΦ), rapidity difference (Δy) and the charm-pair mass variables. They observe some correlation for the longitudinal momenta, and a significant correlation for the transverse momenta of the charm and anticharm particles. They compare the experimental distributions with theoretical predictions based on the photon-gluon fusion model (PGF), for the production of c$\\bar{c}$ quarks, and the standard Lund hadronization model. These models are implemented by the PYTHIA Monte Carlo event generator. The PYTHIA program allows the inclusion, in the simulation, of non-perturbative effects that have been shown to be important for charm production. In order to compare data and simulation, they have generated two Monte Carlo samples, the first one set to favor the production of D$\\bar{D}$ pairs (MCDD2), and the second one set to favor the production of DD_sand DΛ_c pairs, where each one uses different functions and parameters values for the theoretical models in the simulation. They observe, for the correlation distributions, that the set of parameters used by the MCDD2 model together with the intrinsic transverse momentum (k_$\\perp$) of the partons inside the

Generalized dislocated lag function projective synchronization of fractional order chaotic systems with fully uncertain parameters

International Nuclear Information System (INIS)

Wang, Cong; Zhang, Hong-li; Fan, Wen-hui

2017-01-01

In this paper, we propose a new method to improve the safety of secure communication. This method uses the generalized dislocated lag projective synchronization and function projective synchronization to form a new generalized dislocated lag function projective synchronization. Moreover, this paper takes the examples of fractional order Chen system and Lü system with uncertain parameters as illustration. As the parameters of the two systems are uncertain, the nonlinear controller and parameter update algorithms are designed based on the fractional stability theory and adaptive control method. Moreover, this synchronization form and method of control are applied to secure communication via chaotic masking modulation. Many information signals can be recovered and validated. Finally, simulations are used to show the validity and feasibility of the proposed scheme.

Pair-correlations in swimmer suspensions

Science.gov (United States)

Nambiar, Sankalp; Subramanian, Ganesh

2017-11-01

Suspensions of rear-actuated swimming microorganisms, such as E.coli, exhibit several interesting phenomena including spontaneous pattern formation above a critical concentration, novel rheological properties, shear-induced concentration banding etc. Explanations based on mean-field theory are only qualitative, since interactions between swimmers are important for typical experimental concentrations. We analytically characterize the hydrodynamic pair-interactions in a quiescent suspension of slender straight swimmers. The pair-correlation, calculated at leading order by integrating the swimmer velocity disturbances along straight trajectories, decays as 1/r2 for r >> L (L being the swimmer size). This allows us to characterize both polar and nematic correlations in an interacting swimmer suspension. In the absence of correlations, the velocity covariance asymptotes from a constant for r > L, the latter being characteristic of a suspension of non-interacting point force-dipoles. On including correlations, the slow decay of the pair-orientation correlation leads to an additional contribution to the velocity covariance that diverges logarithmically with system size.

Magnetic Fluctuations in Pair-Density-Wave Superconductors

Science.gov (United States)

Christensen, Morten H.; Jacobsen, Henrik; Maier, Thomas A.; Andersen, Brian M.

2016-04-01

Pair-density-wave superconductivity constitutes a novel electronic condensate proposed to be realized in certain unconventional superconductors. Establishing its potential existence is important for our fundamental understanding of superconductivity in correlated materials. Here we compute the dynamical magnetic susceptibility in the presence of a pair-density-wave ordered state and study its fingerprints on the spin-wave spectrum including the neutron resonance. In contrast to the standard case of d -wave superconductivity, we show that the pair-density-wave phase exhibits neither a spin gap nor a magnetic resonance peak, in agreement with a recent neutron scattering experiment on underdoped La1.905 Ba0.095 CuO4 [Z. Xu et al., Phys. Rev. Lett. 113, 177002 (2014)].

The inverse problem for Schwinger pair production

Directory of Open Access Journals (Sweden)

F. Hebenstreit

2016-02-01

Full Text Available The production of electron–positron pairs in time-dependent electric fields (Schwinger mechanism depends non-linearly on the applied field profile. Accordingly, the resulting momentum spectrum is extremely sensitive to small variations of the field parameters. Owing to this non-linear dependence it is so far unpredictable how to choose a field configuration such that a predetermined momentum distribution is generated. We show that quantum kinetic theory along with optimal control theory can be used to approximately solve this inverse problem for Schwinger pair production. We exemplify this by studying the superposition of a small number of harmonic components resulting in predetermined signatures in the asymptotic momentum spectrum. In the long run, our results could facilitate the observation of this yet unobserved pair production mechanism in quantum electrodynamics by providing suggestions for tailored field configurations.

A reduced order model of a quadruped walking system

International Nuclear Information System (INIS)

Sano, Akihito; Furusho, Junji; Naganuma, Nobuyuki

1990-01-01

Trot walking has recently been studied by several groups because of its stability and realizability. In the trot, diagonally opposed legs form pairs. While one pair of legs provides support, the other pair of legs swings forward in preparation for the next step. In this paper, we propose a reduced order model for the trot walking. The reduced order model is derived by using two dominant modes of the closed loop system in which the local feedback at each joint is implemented. It is shown by numerical examples that the obtained reduced order model can well approximate the original higher order model. (author)

On the number of free energy extremums of a solid solution with two long-range order parameters

International Nuclear Information System (INIS)

Dateshidze, N.A.; Ratishvili, I.G.

1977-01-01

The free energy of ordering f.c.c. lattice solid solution is investigated. The ordering is regarded as homogeneous in the whole bulk of the crystal (i.e. resistant towards formation of antiphase domains). It is described by one of the appropriate distribution functions which contains two long-range order parameters. The calculations have revealed the extrema of the free energy function, and their shape and behaviour upon variations of temperature are analyzed. It is shown that under certain circumstances the system can display more than one minimum of free energy within the ordered phase

Excitonic magnet in external field: Complex order parameter and spin currents

Science.gov (United States)

Geffroy, D.; Hariki, A.; Kuneš, J.

2018-04-01

We investigate spin-triplet exciton condensation in the two-orbital Hubbard model close to half-filling by means of dynamical mean-field theory. Employing an impurity solver that handles complex off-diagonal hybridization functions, we study the behavior of excitonic condensate in stoichiometric and doped systems subject to external magnetic field. We find a general tendency of the triplet order parameter to lie perpendicular with the applied field and identify exceptions from this rule. For solutions exhibiting k -odd spin textures, we discuss the Bloch theorem, which, in the absence of spin-orbit coupling, forbids the appearance of spontaneous net spin current. We demonstrate that the Bloch theorem is not obeyed by the dynamical mean-field theory.

General form of Darboux transformations for Lax pairs

International Nuclear Information System (INIS)

Zhou Zixiang.

1988-03-01

In this paper, the author finds all the Darboux transformations for general Lax pair with coefficients analytic to spectral parameter. The auto-Baecklund property of these Darboux transformations for n x n system is also verified. (author). 7 refs

Phonon Dispersion and the Competition between Pairing and Charge Order

Science.gov (United States)

Costa, N. C.; Blommel, T.; Chiu, W.-T.; Batrouni, G.; Scalettar, R. T.

2018-05-01

The Holstein model describes the interaction between fermions and a collection of local (dispersionless) phonon modes. In the dilute limit, the phonon degrees of freedom dress the fermions, giving rise to polaron and bipolaron formation. At higher densities, the phonons mediate collective superconducting (SC) and charge-density wave (CDW) phases. Quantum Monte Carlo (QMC) simulations have considered both these limits but have not yet focused on the physics of more general phonon spectra. Here we report QMC studies of the role of phonon dispersion on SC and CDW order in such models. We quantify the effect of finite phonon bandwidth and curvature on the critical temperature Tcdw for CDW order and also uncover several novel features of diagonal long-range order in the phase diagram, including a competition between charge patterns at momenta q =(π ,π ) and q =(0 ,π ) which lends insight into the relationship between Fermi surface nesting and the wave vector at which charge order occurs. We also demonstrate SC order at half filling in situations where a nonzero bandwidth sufficiently suppresses Tcdw.

Higher order corrections to energy levels of muonic atoms

International Nuclear Information System (INIS)

Rinker, G.A. Jr.; Steffen, R.M.

1975-08-01

In order to facilitate the analysis of muonic x-ray spectra, the results of numerical computations of all higher order quantum electrodynamical corrections to the energy levels of muonic atoms are presented in tabular and graphical form. These corrections include the vacuum polarization corrections caused by emission and reabsorption of virtual electron pairs to all orders, including ''double-bubble'' and ''cracked-egg'' diagrams. An estimate of the Delbruecke scattering-type correction is presented. The Lamb-shift (second- and fourth-order vertex) corrections have been calculated including the correction for the anomalous magnetic moment of the muon. The relativistic nuclear motion (or recoil) correction as well as the correction caused by the screening of the atomic electrons is presented in graphs. For the sake of completeness a graph of the nuclear polarization as computed on the basis of Chen's approach has been included. All calculations were made with a two-parameter Fermi distribution of the nuclear charge density. 7 figures, 23 references

Understanding agent-based models of financial markets: A bottom-up approach based on order parameters and phase diagrams

Science.gov (United States)

Lye, Ribin; Tan, James Peng Lung; Cheong, Siew Ann

2012-11-01

We describe a bottom-up framework, based on the identification of appropriate order parameters and determination of phase diagrams, for understanding progressively refined agent-based models and simulations of financial markets. We illustrate this framework by starting with a deterministic toy model, whereby N independent traders buy and sell M stocks through an order book that acts as a clearing house. The price of a stock increases whenever it is bought and decreases whenever it is sold. Price changes are updated by the order book before the next transaction takes place. In this deterministic model, all traders based their buy decisions on a call utility function, and all their sell decisions on a put utility function. We then make the agent-based model more realistic, by either having a fraction fb of traders buy a random stock on offer, or a fraction fs of traders sell a random stock in their portfolio. Based on our simulations, we find that it is possible to identify useful order parameters from the steady-state price distributions of all three models. Using these order parameters as a guide, we find three phases: (i) the dead market; (ii) the boom market; and (iii) the jammed market in the phase diagram of the deterministic model. Comparing the phase diagrams of the stochastic models against that of the deterministic model, we realize that the primary effect of stochasticity is to eliminate the dead market phase.

On Dual Gabor Frame Pairs Generated by Polynomials

DEFF Research Database (Denmark)

Christensen, Ole; Rae Young, Kim

2010-01-01

We provide explicit constructions of particularly convenient dual pairs of Gabor frames. We prove that arbitrary polynomials restricted to sufficiently large intervals will generate Gabor frames, at least for small modulation parameters. Unfortunately, no similar function can generate a dual Gabo...

Inadmissibility of Usual and Mixed Estimators of Two Ordered Gamma Scale Parameters Under Reflected Gamma Loss Function

OpenAIRE

Z. Meghnatisi; N. Nematollahi

2009-01-01

Let Xi1, · · · , Xini be a random sample from a gamma distribution with known shape parameter νi > 0 and unknown scale parameter βi > 0, i = 1, 2, satisfying 0 < β1 6 β2. We consider the class of mixed estimators for estimation of β1 and β2 under reflected gamma loss function. It has been shown that the minimum risk equivariant estimator of βi, i = 1, 2, which is admissible when no information on the ordering of parameters are given, is inadmissible and dominated by a cla...

Sign of the electron exchange coupling in random radical encounter pairs in solution

International Nuclear Information System (INIS)

Thurnauer, M.C.; Chiu, T.M.; Trifunac, A.D.

1985-01-01

An important parameter in the study of reacting radical systems is the electron exchange interaction, J. The properties of interest are the sign and magnitude of J, and its functional dependence on distance between radicals. One source of information about J is from understanding the Chemically Induced Dynamic Electron Polarization (CIDEP) which is observed in the EPR spectra of reactive radical systems. For radicals reacting in solution to form new covalent bonds, it has generally been found that J O. It is suggested that F-pairs react at a separation greater than that at which spin correlated (geminate) pairs of the same radicals are formed, so that the intervening solvent molecules become involved in the exchange interaction giving rise to J>O via some sort of superexchange process. This is an interesting proposition since superexchange via solvent molecules may play a role in rates of long-distance electron transfer reactions and in the electron transfer reactions of photosynthesis. However, the model suggested runs contrary to all F-air radicals are produced. In order to clarify this important point, the authors present here a definitive study in which we examine several systems of radgenerated independently (exclusive F-pairs) by pulsed laser photolysis and pulsed radiolicals generatedysis in aqueous, alcoholic and hydrocarbon solvents

Order-parameter-aided temperature-accelerated sampling for the exploration of crystal polymorphism and solid-liquid phase transitions

International Nuclear Information System (INIS)

Yu, Tang-Qing; Vanden-Eijnden, Eric; Chen, Pei-Yang; Chen, Ming; Samanta, Amit; Tuckerman, Mark

2014-01-01

The problem of predicting polymorphism in atomic and molecular crystals constitutes a significant challenge both experimentally and theoretically. From the theoretical viewpoint, polymorphism prediction falls into the general class of problems characterized by an underlying rough energy landscape, and consequently, free energy based enhanced sampling approaches can be brought to bear on the problem. In this paper, we build on a scheme previously introduced by two of the authors in which the lengths and angles of the supercell are targeted for enhanced sampling via temperature accelerated adiabatic free energy dynamics [T. Q. Yu and M. E. Tuckerman, Phys. Rev. Lett. 107, 015701 (2011)]. Here, that framework is expanded to include general order parameters that distinguish different crystalline arrangements as target collective variables for enhanced sampling. The resulting free energy surface, being of quite high dimension, is nontrivial to reconstruct, and we discuss one particular strategy for performing the free energy analysis. The method is applied to the study of polymorphism in xenon crystals at high pressure and temperature using the Steinhardt order parameters without and with the supercell included in the set of collective variables. The expected fcc and bcc structures are obtained, and when the supercell parameters are included as collective variables, we also find several new structures, including fcc states with hcp stacking faults. We also apply the new method to the solid-liquid phase transition in copper at 1300 K using the same Steinhardt order parameters. Our method is able to melt and refreeze the system repeatedly, and the free energy profile can be obtained with high efficiency

On the pair creation effect in radiative charmonium transitions

International Nuclear Information System (INIS)

Lewin, K.

1985-01-01

Contribution to radiative charmonium decay amplitudes which come from Feynman diagrams containing creation of internal c anti c quark pair is investigated. The a im of the paper is calulation of this pair creation correction to the wave function overlap integral of the transition amplitude in a quasilocal semirelativistic approximation which works for charmed and heavier quark pairs. The application to the decay width of the spin flip transition psi(3685) → γchi(3415) givesa 12% correction to the nopair term using a meson radius near 0.5 Fm and a scale parameter Λ=400 MeV taken from fits inchar=monium spectroscopy. The error of the approximation is estimated to be smaller than 50%. The investigation indicates that also in the case of electroweak meson decays quatitative results cannot be expected from the no-pair contribution alone

Adatom pair distribution up to half coverage: O-Pd(100)

OpenAIRE

Kappus, Wolfgang

2017-01-01

Using substrate mediated elastic interactions fitted previously to first principles (FP) calculations, adatom pair distributions are derived for O-Pd(100) evaluating a statistical BGY based integral equation. The evaluation method utilizes the superposition approximation, a temperature scaling scheme, and for one variant the particle-hole symmetry of a pair interaction lattice gas Hamiltonian. The elastic Hamiltonian is taken from a previous 3 parameter analytical model. The resulting adatom ...

Joint Testlet Cognitive Diagnosis Modeling for Paired Local Item Dependence in Response Times and Response Accuracy

Directory of Open Access Journals (Sweden)

Peida Zhan

2018-04-01

Full Text Available In joint models for item response times (RTs and response accuracy (RA, local item dependence is composed of local RA dependence and local RT dependence. The two components are usually caused by the same common stimulus and emerge as pairs. Thus, the violation of local item independence in the joint models is called paired local item dependence. To address the issue of paired local item dependence while applying the joint cognitive diagnosis models (CDMs, this study proposed a joint testlet cognitive diagnosis modeling approach. The proposed approach is an extension of Zhan et al. (2017 and it incorporates two types of random testlet effect parameters (one for RA and the other for RTs to account for paired local item dependence. The model parameters were estimated using the full Bayesian Markov chain Monte Carlo (MCMC method. The 2015 PISA computer-based mathematics data were analyzed to demonstrate the application of the proposed model. Further, a brief simulation study was conducted to demonstrate the acceptable parameter recovery and the consequence of ignoring paired local item dependence.

Microscopic interplay of superconducting and magnetic order parameters in ferropnictides

Energy Technology Data Exchange (ETDEWEB)

Maeter, H.; Goltz, T.; Spehling, J.; Klauss, H.H. [Institut fuer Festkoerperphysik, TU Dresden (Germany); Bendele, M.; Luetkens, H.; Khasanov, R.; Pascua, G.; Shermadini, Z.; Amato, A. [Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, Villigen (Switzerland); Aswartham, S.; Hamann-Borrero, J.E.; Kondrat, A.; Hess, C.; Wolter, A.; Wurmehl, S.; Behr, G.; Buechner, B. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung Dresden (Germany); Wiesenmayer, E.; Johrendt, D. [Department Chemie, Ludwig-Maximilians-Universitaet Muenchen (Germany); Potts, H.; Banusch, B. [Swiss Nanoscience Institute, Universitaet Basel (Switzerland)

2012-07-01

We present results of {mu}SR experiments of Ba{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2} that show a large coupling of the superconducting and magnetic order parameters. This is unexpected in light of the phase separation in Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2}. However, in a {mu}SR study of Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} we unambiguously showed microscopic coexistence, even though there are many reports of phase separation in this system. In FeSe{sub 1-x} the interplay of phase separation and microscopic coexistence is also evident, here pressure can induce a change from microscopic coexistence to a combination of both. In light of the {mu}SR results it seems likely that phase separation and microscopic coexistence depend on the microscopic properties much more than on disorder.

Solitary attractors and low-order filamentation in anisotropic self-focusing media

DEFF Research Database (Denmark)

Zozulya, A.A.; Anderson, D.Z.; Mamaev, A.V.

1998-01-01

We present a detailed theoretical analysis of the properties and formation of single solitons and higher-order bound dipole pairs in media with anisotropic nonlocal photorefractive material response. The single solitons are elliptical beams, whereas the dipole pairs are formed by a pair of displa......We present a detailed theoretical analysis of the properties and formation of single solitons and higher-order bound dipole pairs in media with anisotropic nonlocal photorefractive material response. The single solitons are elliptical beams, whereas the dipole pairs are formed by a pair...

Microsecond molecular dynamics simulation shows effect of slow loop dynamics on backbone amide order parameters of proteins

DEFF Research Database (Denmark)

Maragakis, Paul; Lindorff-Larsen, Kresten; Eastwood, Michael P

2008-01-01

. Molecular dynamics (MD) simulation provides a complementary approach to the study of protein dynamics on similar time scales. Comparisons between NMR spectroscopy and MD simulations can be used to interpret experimental results and to improve the quality of simulation-related force fields and integration......A molecular-level understanding of the function of a protein requires knowledge of both its structural and dynamic properties. NMR spectroscopy allows the measurement of generalized order parameters that provide an atomistic description of picosecond and nanosecond fluctuations in protein structure...... methods. However, apparent systematic discrepancies between order parameters extracted from simulations and experiments are common, particularly for elements of noncanonical secondary structure. In this paper, results from a 1.2 micros explicit solvent MD simulation of the protein ubiquitin are compared...

Charm quark pair correlations with D*-muon tag at HERA

International Nuclear Information System (INIS)

Gladkov, D.

2007-07-01

This thesis presents a measurement of double-tagged charm quark pair production via the process ep→e' ccX→e' D*μX' in lepton-proton collisions at HERA, using an integrated luminosity of 114 pb -1 gated by the ZEUS detector in the years 1996-2000. Since the charm quark mass provides a large enough energy scale, the perturbative Quantum Chromo-Dynamics approach can be used to calculate the cross section for charm D*-muon pairs. Using the D*-muon pair to tag the charm quark pair, the measurement is sensitive not only to properties of the leading order hard scattering process but also to the hadronisation and the parton density in the proton as well as higher order effects. Employing the angular and charge correlations between the D* meson and the muon, the fraction of charm events is extracted from the data. Cross sections for charm D*-muon pair production in the visible range of the D* transverse momentum p T D* >1.5 GeV, the D* pseudorapidity vertical stroke η D* vertical stroke T μ >1.0 GeV and the muon pseudorapidity vertical stroke η μ vertical stroke 2 2 ) and deep inelastic scattering (y 2 >2 GeV 2 ) regimes. For the inclusive and photoproduction regimes differential cross sections in various kinematic variables of the D*-muon pair are measured as well. The differential cross sections for the inclusive regime are compared to the leading order plus parton shower MC approach, while the differential cross sections for the photoproduction regime are compared to next-to leading order calculations. The momentum fraction carried by the gluon in the proton is also measured. The possibility of extending the Global Track Trigger of the ZEUS DAQ/trigger system with a forward trigger algorithm is the technical task of this thesis. A forward trigger algorithm has been written which finds the event vertex position using STT and FMVD detector data. (orig.)

Few-photon electron-positron pair creation in the collision of a relativistic nucleus and an intense x-ray laser beam

International Nuclear Information System (INIS)

Mueller, C.; Gruen, N.; Voitkiv, A.B.

2004-01-01

We study the nonlinear process of e - e + pair creation by a nucleus which moves at a relativistic energy in the laboratory frame and collides with an intense x-ray laser beam. The collision system under consideration is chosen in such a way that the simultaneous absorption of at least two photons from the laser wave is required in order to exceed the energy threshold of the reaction. We calculate total and differential rates for both free-free and bound-free pair production. In the case of free-free pair creation we demonstrate the effect of the laser polarization on the spectra of the produced particles, and we show that at very high intensities the total rate exhibits features analogous to those well known from above-threshold ionization rates for atoms. In the case of bound-free pair creation a singularity is found in the laboratory frame angular distribution of the produced positron. This singularity represents a distinct characteristic of the bound-free pair production and allows one to separate this process from free-free pair creation even without detecting a bound state of the captured electron. For both types of pair creation we consider the dependences of the total rates on the collision parameters, give the corresponding scaling laws, and discuss the possibility to observe these nonlinear processes in a future experiment

Modeling top quark pair production in the search of new, heavy resonance that decays into a pair of Higgs bosons

CERN Document Server

Liyanage, Kalpanie Madara

2017-01-01

The Higgs boson pair production process at the LHC provides an opportunity for performing a study of the trilinear Higgs boson self-coupling. We consider Higgs boson pair production in the bbWW*channel, with subsequent decay of the WW* pair into lνqq. Due to irreducible top quark backgrounds and the associated uncertainties, this is a challenging final state to explore. We apply appropriate selection cuts on suitable kinematic variables in order to obtain a signal-enriched region. Using several different Monte Carlo (MC) samples the top quark background process is then studied in this region of interest. We find that depending on the phase space, different MC samples lead to kinematic differences.

Pairing and superconductivity from weak to strong coupling in the attractive Hubbard model

International Nuclear Information System (INIS)

Toschi, A; Barone, P; Capone, M; Castellani, C

2005-01-01

The finite-temperature phase diagram of the attractive Hubbard model is studied by means of the dynamical mean-field theory. We first consider the normal phase of the model by explicitly frustrating the superconducting ordering. In this case, we obtain a first-order pairing transition between a metallic phase and a paired phase formed by strongly coupled incoherent pairs. The transition line ends in a finite temperature critical point, but a crossover between two qualitatively different solutions still occurs at higher temperature. Comparing the superconducting- and the normal-phase solutions, we find that the superconducting instability always occurs before the pairing transition in the normal phase, i.e. T c > T pairing . Nevertheless, the high-temperature phase diagram at T > T c is still characterized by a crossover from a metallic phase to a preformed pair phase. We characterize this crossover by computing different observables that can be used to identify the pseudogap region, like the spin susceptibility, the specific heat and the single-particle spectral function

Nonlinear optical effects and third-harmonic generation in superconductors: Cooper pairs versus Higgs mode contribution

Science.gov (United States)

Cea, T.; Castellani, C.; Benfatto, L.

2016-05-01

The recent observation of a transmitted THz pulse oscillating at three times the frequency of the incident light paves the way to a powerful protocol to access resonant excitations in a superconductor. Here we show that this nonlinear optical process is dominated by light-induced excitation of Cooper pairs, while the collective amplitude (Higgs) fluctuations of the superconducting order parameter give in general a negligible contribution. We also predict a nontrivial dependence of the signal on the direction of the light polarization with respect to the lattice symmetry, which can be tested in systems such as, e.g., cuprate superconductors.

Structural order parameter in the pyrochlore superconductor Cd sub 2 Re sub 2 O sub 7

CERN Document Server

Sergienko, I A

2003-01-01

It is shown that both structural phase transitions in Cd sub 2 Re sub 2 O sub 7 , which occur at T sub s sub 1 = 200 K and T sub s sub 2 = 120 K, are due to an instability of the Re tetrahedral network with respect to the same doubly degenerate long-wavelength phonon mode. The primary structural order parameter transforms according to the irreducible representation E sub u of the point group O sub h. We argue that the transition at T sub s sub 1 may be of the second order, in accordance with experimental data. We obtain the phase diagram in the space of phenomenological parameters and propose a thermodynamic path that Cd sub 2 Re sub 2 O sub 7 follows upon cooling. Coupling of the itinerant electronic system and localized spin states in pyrochlores and spinels to atomic displacements are discussed. (author)

Applications of SCET to the pair production of supersymmetric particles at hadron colliders

Energy Technology Data Exchange (ETDEWEB)

Broggio, Alessandro

2013-02-04

In this thesis we investigate the phenomenology of supersymmetric particles at hadron colliders beyond next-to-leading order (NLO) in perturbation theory. We discuss the foundations of Soft-Collinear Effective Theory (SCET) and, in particular, we explicitly construct the SCET Lagrangian for QCD. As an example, we discuss factorization and resummation for the Drell-Yan process in SCET. We use techniques from SCET to improve existing calculations of the production cross sections for slepton-pair production and top-squark-pair production at hadron colliders. As a first application, we implement soft-gluon resummation at next-to-next-to-next-to-leading logarithmic order (NNNLL) for slepton-pair production in the minimal supersymmetric extension of the Standard Model (MSSM). This approach resums large logarithmic corrections arising from the dynamical enhancement of the partonic threshold region caused by steeply falling parton luminosities. We evaluate the resummed invariant-mass distribution and total cross section for slepton-pair production at the Tevatron and LHC and we match these results, in the threshold region, onto NLO fixed-order calculations. As a second application we present the most precise predictions available for top-squark-pair production total cross sections at the LHC. These results are based on approximate NNLO formulas in fixed-order perturbation theory, which completely determine the coefficients multiplying the singular plus distributions. The analysis of the threshold region is carried out in pair invariant mass (PIM) kinematics and in single-particle inclusive (1PI) kinematics. We then match our results in the threshold region onto the exact fixed-order NLO results and perform a detailed numerical analysis of the total cross section.

Determination of thermodynamical coefficients for Mo-W alloys according to short-range order parameters

International Nuclear Information System (INIS)

Erokhin, L.N.; Mokrov, A.P.; Shivrin, O.N.; Khanina, N.I.

1986-01-01

A method is proposed for determining thermodynamical coefficients according to short-range order parameters. The method approbation for Mo-W alloys has shown a good agreement between the thermodynamical and diffusion data. The Mo-W system in the concentration range under study is close to the ideal one. The calculated relative error of determination of interdiffusion coefficients in alloys of the Mo-W system does not exceed 16%

Solitons and rogue waves for a higher-order nonlinear Schroedinger-Maxwell-Bloch system in an erbium-doped fiber

International Nuclear Information System (INIS)

Su, Chuan-Qi; Gao, Yi-Tian; Yu, Xin; Xue, Long; Aviation Univ. of Air Force, Liaoning

2015-01-01

Under investigation in this article is a higher-order nonlinear Schroedinger-Maxwell-Bloch (HNLS-MB) system for the optical pulse propagation in an erbium-doped fiber. Lax pair, Darboux transformation (DT), and generalised DT for the HNLS-MB system are constructed. Soliton solutions and rogue wave solutions are derived based on the DT and generalised DT, respectively. Properties of the solitons and rogue waves are graphically presented. The third-order dispersion parameter, fourth-order dispersion parameter, and frequency detuning all influence the characteristic lines and velocities of the solitons. The frequency detuning also affects the amplitudes of solitons. The separating function has no effect on the properties of the first-order rogue waves, except for the locations where the first-order rogue waves appear. The third-order dispersion parameter affects the propagation directions and shapes of the rogue waves. The frequency detuning influences the rogue-wave types of the module for the measure of polarization of resonant medium and the extant population inversion. The fourth-order dispersion parameter impacts the rogue-wave interaction range and also has an effect on the rogue-wave type of the extant population inversion. The value of separating function affects the spatial-temporal separation of constituting elementary rogue waves for the second-order and third-order rogue waves. The second-order and third-order rogue waves can exhibit the triangular and pentagon patterns under different choices of separating functions.

Lepton-pair production by bremsstrahlung in central relativistic heavy ion collisions

International Nuclear Information System (INIS)

Lippert, T.; Becker, U.; Gruen, N.; Scheid, W.; Soff, G.

1988-03-01

We study the production of lepton-pairs by classical bremsstrahlung in central relativistic heavy-ion collisions. For the stopping of the nuclei we assume a simple model of point charges and a deceleration time. Pair creation probabilities are calculated in first order perturbation theory. (orig.)

Pair creation by dynamic field configurations

International Nuclear Information System (INIS)

Aoyama, H.

1982-01-01

This thesis deals with the dynamics of the classical configuration of a quantum field unstable due to pair creation. The effective action method is developed first to treat such problems for a simple two-field model. Physical quantities such as pair creation probabilities are related to a complex function called the effective configuration, which is defined to minimize the effective action. Unitarity of the S-matrix is verified at the lowest order of the weak-field approximation. At the same order, the real valued vacuum expectation value of the quantum field, named the real configuration, is constructed in terms of the effective configuration. An integro-differential equation for the real configuration is given and is used to show that the real configuration is causal, while the effective configuration is not. Two practical applications of the effective action method are discussed. The first deals with pair creation in an anisotropic universe, and the real geometry is given in terms of the effective geometry in the samll anisotropy limit. The second deals with expanding vacuum bubbles. Corresponding to three possible situations, three kinds of field equations of each of the effective configuration and the real configuration are obtained. The behavior of the bubble is also studied by a semi-classical method, and one of the three situations is suggested to be plausible

A brief note on the magnecule order parameter upgrade hypothesis

International Nuclear Information System (INIS)

Schmidt, Nathan O.

2015-01-01

In this short remark, we report on recent hypothetical work that aims to equip Santilli’s magnecule model with topological deformation order parameters (OP) of fractional statistics to define a preliminary set of wavepacket wavefunctions for the electron toroidal polarizations. The primary objective is to increase the representational precision and predictive accuracy of the magnecule model by exemplifying the fluidic characteristics for direct industrial application. In particular, the OPs are deployed to encode the spontaneous superfluidic gauge symmetry breaking (which may be restored at the iso-topic level) and correlated with Leggett’s superfluid B phases to establish a long range constraint for the wavefunctions. These new, developing, theoretical results may be significant because the OP configuration arms us with an extra degree of freedom for encoding a magnecule’s states and transitions, which may reveal further insight into the underlying physical mechanisms and features associated with these state-of-the-art magnecular bonds

Optimization Design of Multi-Parameters in Rail Launcher System

Directory of Open Access Journals (Sweden)

Yujiao Zhang

2014-05-01

Full Text Available Today the energy storage systems are still encumbering, therefore it is useful to think about the optimization of a railgun system in order to achieve the best performance with the lowest energy input. In this paper, an optimal design method considering 5 parameters is proposed to improve the energy conversion efficiency of a simple railgun. In order to avoid costly trials, the field- circuit method is employed to analyze the operations of different structural railguns with different parameters respectively. And the orthogonal test approach is used to guide the simulation for choosing the better parameter combinations, as well reduce the calculation cost. The research shows that the proposed method gives a better result in the energy efficiency of the system. To improve the energy conversion efficiency of electromagnetic rail launchers, the selection of more parameters must be considered in the design stage, such as the width, height and length of rail, the distance between rail pair, and pulse forming inductance. However, the relationship between these parameters and energy conversion efficiency cannot be directly described by one mathematical expression. So optimization methods must be applied to conduct design. In this paper, a rail launcher with five parameters was optimized by using orthogonal test method. According to the arrangement of orthogonal table, the better parameters’ combination can be obtained through less calculation. Under the condition of different parameters’ value, field and circuit simulation analysis were made. The results show that the energy conversion efficiency of the system is increased by 71.9 % after parameters optimization.

Energy gap in S- and D-wave pairing superconductors

International Nuclear Information System (INIS)

Dolgov, O.V.; Golubov, A.A.

1988-01-01

In this paper the ratio of 2Δ g /T c , where Δ g is the gap edge, T c is the critical temperature, is calculated in the framework of the model of strong electron-phonon coupling. Both isotropic and anisotropic pairing cases are considered. It is shown that the isotropic Eliashberg model can not account for the large values of the ratio 2Δ g /T c for the reasonable values of the electron-phonon coupling parameter λ while anisotropic pairing can resolve this problem

Fluctuations in substitution type alloys and their analyses. Short-range order structures

International Nuclear Information System (INIS)

Iwasaki, Hiroshi; Ohshima, Ken-ichi

2010-01-01

This article is the fifth of the serial lecture, microstructures and fluctuations, in this magazine. The formula of X-ray diffuse scattering intensity was derived for binary alloys by introducing short-range order parameters. Diffuse scattering intensities for a single crystal Cu 3 Au were measured above critical temperature for ordering. The short-range parameters were obtained by a three-dimensional Fourier analysis. The long-range pair interaction between atoms was originated from the indirect screening interaction due to conduction electrons. A detailed study was made on short-range-order diffuse scattering from Cu 3 Au in the disordered state by electron diffraction. Fourfold splitting of the diffuse scattering was observed at 110 in the reciprocal lattice, and this result was attributed to the reflection of the form of the Fermi surface. The X-ray diffuse scattering intensity was measured at room temperature for disordered Cu-Pd alloys for the six composition of Pd. Twofold and fourfold splitting of diffuse scattering due to the short-range order (SRO) were observed at 100, 110 and equivalent positions respectively from alloys with more than 13.0at% Pd. The SRO parameters were determined from all the six alloys. For Cu-Pt alloys, the diffuse scattering originated from the correlation between Cu and Pt layers in direction was observed in addition to the one due to the reflection of the Fermi surface imaging. (author)

Apomorphine conditioning and sensitization: the paired/unpaired treatment order as a new major determinant of drug conditioned and sensitization effects.

Science.gov (United States)

de Matos, Liana Wermelinger; Carey, Robert J; Carrera, Marinete Pinheiro

2010-09-01

Repeated treatments with psychostimulant drugs generate behavioral sensitization. In the present study we employed a paired/unpaired protocol to assess the effects of repeated apomorphine (2.0 mg/kg) treatments upon locomotion behavior. In the first experiment we assessed the effects of conditioning upon apomorphine sensitization. Neither the extinction of the conditioned response nor a counter-conditioning procedure in which we paired an inhibitory treatment (apomorphine 0.05 mg/kg) with the previously established conditioned stimulus modified the sensitization response. In the second experiment, we administered the paired/unpaired protocol in two phases. In the second phase, we reversed the paired/unpaired protocol. Following the first phase, the paired group alone exhibited conditioned locomotion in the vehicle test and a sensitization response. In the second phase, the initial unpaired group which received 5 paired apomorphine trials during the reversal phase did not develop a conditioned response but developed a potentiated sensitization response. This disassociation of the conditioned response from the sensitization response is attributed to an apomorphine anti-habituation effect that can generate a false positive Pavlovian conditioned response effect. The potentiated sensitization response induced by the treatment reversal protocol points to an important role for the sequential experience of the paired/unpaired protocol in behavioral sensitization. 2010 Elsevier Inc. All rights reserved.

DYNAMIC ESTIMATION FOR PARAMETERS OF INTERFERENCE SIGNALS BY THE SECOND ORDER EXTENDED KALMAN FILTERING

Directory of Open Access Journals (Sweden)

P. A. Ermolaev

2014-03-01

Full Text Available Data processing in the interferometer systems requires high-resolution and high-speed algorithms. Recurrence algorithms based on parametric representation of signals execute consequent processing of signal samples. In some cases recurrence algorithms make it possible to increase speed and quality of data processing as compared with classic processing methods. Dependence of the measured interferometer signal on parameters of its model and stochastic nature of noise formation in the system is, in general, nonlinear. The usage of nonlinear stochastic filtering algorithms is expedient for such signals processing. Extended Kalman filter with linearization of state and output equations by the first vector parameters derivatives is an example of these algorithms. To decrease approximation error of this method the second order extended Kalman filtering is suggested with additionally usage of the second vector parameters derivatives of model equations. Examples of algorithm implementation with the different sets of estimated parameters are described. The proposed algorithm gives the possibility to increase the quality of data processing in interferometer systems in which signals are forming according to considered models. Obtained standard deviation of estimated amplitude envelope does not exceed 4% of the maximum. It is shown that signal-to-noise ratio of reconstructed signal is increased by 60%.

Change in the order parameter of a superconductor of type I in the presence of magnetic dipoles

International Nuclear Information System (INIS)

Lebeau, C.; Pinel, J.

1977-01-01

Taking the order parameter to be spatially constant, we show that magnetic dipoles modify the energy with a term proportional to the difference between the local fields in the normal and supercondcuting states. Evaluation of this difference predicts a second-order transition. The transition temperature only depends on the mean value of ferromagnetic magnetisation. Specific heat and susceptibility measurements made on HgFe are compared with this model [fr

Pair interaction of bilayer-coated nanoscopic particles

International Nuclear Information System (INIS)

Qi-Yi, Zhang

2009-01-01

The pair interaction between bilayer membrane-coated nanosized particles has been explored by using the self-consistent field (SCF) theory. The bilayer membranes are composed of amphiphilic polymers. For different system parameters, the pair-interaction free energies are obtained. Particular emphasis is placed on the analysis of a sequence of structural transformations of bilayers on spherical particles, which occur during their approaching processes. For different head fractions of amphiphiles, the asymmetrical morphologies between bilayers on two particles and the inverted micellar intermediates have been found in the membrane fusion pathway. These results can benefit the fabrication of vesicles as encapsulation vectors for drug and gene delivery. (condensed matter: structure, thermal and mechanical properties)

Derivation and solution of a time-dependent, nonlinear, Schrodinger-like equation for the superconductivity order parameter

International Nuclear Information System (INIS)

Esrick, M.A.

1981-01-01

A time-dependent, nonlinear, Schrodinger-like equation for the superconductivity order parameter is derived from the Gor'kov equations. Three types of traveling wave solutions of the equation are discussed. The phases and amplitudes of these solutions propagate at different speeds. The first type of solution has an amplitude that propagates as a soliton and it is suggested that this solution might correspond to the recently observed propagating collective modes of the order parameter. The amplitude of the second type of solution propagates as a periodic disturbance in space and time. It is suggested that this type of solution might explain the recently observed multiple values of the superconductor energy gap as well as the spatially inhomogenous superconducting state. The third type of solution, which is of a more general character, might provide some insight into non-periodic, inhomogeneous states occuring in superconductors. It is also proposed that quasiparticle injection and microwave irradiation might generate soliton-like disturbances in superconductors

Health Parameter Estimation with Second-Order Sliding Mode Observer for a Turbofan Engine

Directory of Open Access Journals (Sweden)

Xiaodong Chang

2017-07-01

Full Text Available In this paper the problem of health parameter estimation in an aero-engine is investigated by using an unknown input observer-based methodology, implemented by a second-order sliding mode observer (SOSMO. Unlike the conventional state estimator-based schemes, such as Kalman filters (KF and sliding mode observers (SMO, the proposed scheme uses a “reconstruction signal” to estimate health parameters modeled as artificial inputs, and is not only applicable to long-time health degradation, but reacts much quicker in handling abrupt fault cases. In view of the inevitable uncertainties in engine dynamics and modeling, a weighting matrix is created to minimize such effect on estimation by using the linear matrix inequalities (LMI. A big step toward uncertainty modeling is taken compared with our previous SMO-based work, in that uncertainties are considered in a more practical form. Moreover, to avoid chattering in sliding modes, the super-twisting algorithm (STA is employed in observer design. Various simulations are carried out, based on the comparisons between the KF-based scheme, the SMO-based scheme in our earlier research, and the proposed method. The results consistently demonstrate the capabilities and advantages of the proposed approach in health parameter estimation.

IBM parameters derived from realistic shell-model Hamiltonian via Hn-cooling method

International Nuclear Information System (INIS)

Nakada, Hitoshi

1997-01-01

There is a certain influence of non-collective degrees-of-freedom even in lowest-lying states of medium-heavy nuclei. This influence seems to be significant for some of the IBM parameters. In order to take it into account, several renormalization approaches have been applied. It has been shown in the previous studies that the influence of the G-pairs is important, but does not fully account for the fitted values. The influence of the non-collective components may be more serious when we take a realistic effective nucleonic interaction. To incorporate this influence into the IBM parameters, we employ the recently developed H n -cooling method. This method is applied to renormalize the wave functions of the states consisting of the SD-pairs, for the Cr-Fe nuclei. On this ground, the IBM Hamiltonian and transition operators are derived from corresponding realistic shell-model operators, for the Cr-Fe nuclei. Together with some features of the realistic interaction, the effects of the non-SD degrees-of-freedom are presented. (author)

Reassessment of the recombination parameters of chromium in n- and p-type crystalline silicon and chromium-boron pairs in p-type crystalline silicon

International Nuclear Information System (INIS)

Sun, Chang; Rougieux, Fiacre E.; Macdonald, Daniel

2014-01-01

Injection-dependent lifetime spectroscopy of both n- and p-type, Cr-doped silicon wafers with different doping levels is used to determine the defect parameters of Cr i and CrB pairs, by simultaneously fitting the measured lifetimes with the Shockley-Read-Hall model. A combined analysis of the two defects with the lifetime data measured on both n- and p-type samples enables a significant tightening of the uncertainty ranges of the parameters. The capture cross section ratios k = σ n /σ p of Cr i and CrB are determined as 3.2 (−0.6, +0) and 5.8 (−3.4, +0.6), respectively. Courtesy of a direct experimental comparison of the recombination activity of chromium in n- and p-type silicon, and as also suggested by modelling results, we conclude that chromium has a greater negative impact on carrier lifetimes in p-type silicon than n-type silicon with similar doping levels.

Enhancing second-order conditioning with lesions of the basolateral amygdala.

Science.gov (United States)

Holland, Peter C

2016-04-01

Because the occurrence of primary reinforcers in natural environments is relatively rare, conditioned reinforcement plays an important role in many accounts of behavior, including pathological behaviors such as the abuse of alcohol or drugs. As a result of pairing with natural or drug reinforcers, initially neutral cues acquire the ability to serve as reinforcers for subsequent learning. Accepting a major role for conditioned reinforcement in everyday learning is complicated by the often-evanescent nature of this phenomenon in the laboratory, especially when primary reinforcers are entirely absent from the test situation. Here, I found that under certain conditions, the impact of conditioned reinforcement could be extended by lesions of the basolateral amygdala (BLA). Rats received first-order Pavlovian conditioning pairings of 1 visual conditioned stimulus (CS) with food prior to receiving excitotoxic or sham lesions of the BLA, and first-order pairings of another visual CS with food after that surgery. Finally, each rat received second-order pairings of a different auditory cue with each visual first-order CS. As in prior studies, relative to sham-lesioned control rats, lesioned rats were impaired in their acquisition of second-order conditioning to the auditory cue paired with the first-order CS that was trained after surgery. However, lesioned rats showed enhanced and prolonged second-order conditioning to the auditory cue paired with the first-order CS that was trained before amygdala damage was made. Implications for an enhanced role for conditioned reinforcement by drug-related cues after drug-induced alterations in neural plasticity are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Comparative study of the requantization of the time-dependent mean field for the dynamics of nuclear pairing

Science.gov (United States)

Ni, Fang; Nakatsukasa, Takashi

2018-04-01

To describe quantal collective phenomena, it is useful to requantize the time-dependent mean-field dynamics. We study the time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory for the two-level pairing Hamiltonian, and compare results of different quantization methods. The one constructing microscopic wave functions, using the TDHFB trajectories fulfilling the Einstein-Brillouin-Keller quantization condition, turns out to be the most accurate. The method is based on the stationary-phase approximation to the path integral. We also examine the performance of the collective model which assumes that the pairing gap parameter is the collective coordinate. The applicability of the collective model is limited for the nuclear pairing with a small number of single-particle levels, because the pairing gap parameter represents only a half of the pairing collective space.

Quad-thopter: Tailless Flapping Wing Robot with 4 Pairs of Wings

NARCIS (Netherlands)

de Wagter, C.; Karasek, M.; de Croon, G.C.H.E.; J.-M. Moschetta G. Hattenberger, H. de Plinval

2017-01-01

We present a novel design of a tailless flapping wing Micro Air Vehicle (MAV), which uses four independently driven pairs of flapping wings in order to fly and perform agile maneuvers. The wing pairs are arranged such that differential thrust generates the desired roll and pitch moments, similar to

Electron-positron pair production in inhomogeneous electromagnetic fields

International Nuclear Information System (INIS)

Kohlfürst, C.

2015-01-01

The process of electron-positron pair production is investigated within the phase-space Wigner formalism. The similarities between atomic ionization and pair production for homogeneous, but time-dependent linearly polarized electric fields are examined mainly in the regime of multiphoton absorption (field-dependent threshold, above-threshold pair production). Characteristic signatures in the particle spectra are identified (effective mass, channel closing). The non-monotonic dependence of the particle yield on the carrier frequency is discussed as well. The investigations are then extended to spatially inhomogeneous electric fields. New effects arising due to the spatial dependence of the effective mass are discussed in terms of a semi-classical interpretation. An increase in the normalized particle yield is found for various field configurations.Pair production in inhomogeneous electric and magnetic fields is also studied. The influence of a time-dependent spatially inhomogeneous magnetic field on the momentum spectrum and the particle yield is investigated. The Lorentz invariants are identified to be crucial in order to understand pair production by strong electric fields in the presence of strong magnetic fields. (author) [de

Cooper-pair size and binding energy for unconventional superconducting systems

Science.gov (United States)

Dinóla Neto, F.; Neto, Minos A.; Salmon, Octavio D. Rodriguez

2018-06-01

The main proposal of this paper is to analyze the size of the Cooper pairs composed by unbalanced mass fermions from different electronic bands along the BCS-BEC crossover and study the binding energy of the pairs. We are considering an interaction between fermions with different masses leading to an inter-band pairing. In addiction to the attractive interaction we have an hybridization term to couple both bands, which in general acts unfavorable for the pairing between the electrons. We get first order phase transitions as the hybridization breaks the Cooper pairs for the s-wave symmetry of the gap amplitude. The results show the dependence of the Cooper-pair size as a function of the hybridization for T = 0 . We also propose the structure of the binding energy of the inter-band system as a function of the two-bands quasi-particle energies.

Predictive labeling with dependency pairs using SAT

NARCIS (Netherlands)

Koprowski, A.; Middeldorp, A.; Pfenning, F.

2007-01-01

This paper combines predictive labeling with dependency pairs and reports on its implementation. Our starting point is the method of proving termination of rewrite systems using semantic labeling with infinite models in combination with lexicographic path orders. We replace semantic labeling with

Assessing local structure motifs using order parameters for motif recognition, interstitial identification, and diffusion path characterization

Science.gov (United States)

Zimmermann, Nils E. R.; Horton, Matthew K.; Jain, Anubhav; Haranczyk, Maciej

2017-11-01

Structure-property relationships form the basis of many design rules in materials science, including synthesizability and long-term stability of catalysts, control of electrical and optoelectronic behavior in semiconductors as well as the capacity of and transport properties in cathode materials for rechargeable batteries. The immediate atomic environments (i.e., the first coordination shells) of a few atomic sites are often a key factor in achieving a desired property. Some of the most frequently encountered coordination patterns are tetrahedra, octahedra, body and face-centered cubic as well as hexagonal closed packed-like environments. Here, we showcase the usefulness of local order parameters to identify these basic structural motifs in inorganic solid materials by developing classification criteria. We introduce a systematic testing framework, the Einstein crystal test rig, that probes the response of order parameters to distortions in perfect motifs to validate our approach. Subsequently, we highlight three important application cases. First, we map basic crystal structure information of a large materials database in an intuitive manner by screening the Materials Project (MP) database (61,422 compounds) for element-specific motif distributions. Second, we use the structure-motif recognition capabilities to automatically find interstitials in metals, semiconductor, and insulator materials. Our Interstitialcy Finding Tool (InFiT) facilitates high-throughput screenings of defect properties. Third, the order parameters are reliable and compact quantitative structure descriptors for characterizing diffusion hops of intercalants as our example of magnesium in MnO2-spinel indicates. Finally, the tools developed in our work are readily and freely available as software implementations in the pymatgen library, and we expect them to be further applied to machine-learning approaches for emerging applications in materials science.

Importance of interlayer pair tunneling: A variational perspective

International Nuclear Information System (INIS)

Medhi, Amal; Basu, Saurabh

2011-01-01

We study the effect of interlayer pair tunneling in a bilayer superconductor where each layer is described by a two dimensional t-J model and the two layers are connected by the Josephson pair tunneling term. We study this model using a grand canonical variational Monte Carlo (GVMC) method, for which we develop a new algorithm to perform Monte Carlo simulation of a system with fluctuating particle number. The variational wavefunction is taken to be the product of two Gutzwiller projected d-wave BCS wavefunctions with variable particle densities, one for each layer. We calculate the energy of the above state as a function of the d-wave superconducting gap parameter, Δ. We find that the interlayer pair tunneling energy, E perpendicular shows interesting variation with Δ. E perpendicular tends to enhance the optimal value of Δ, thereby the superconducting pairing. However the magnitude of the tunneling energy is found to be too small to have any appreciable effect on the physical properties. While the result is supported by early experiments and hence may appear known to the community, the current work presents a new approach to the problem and confirms the diminished role of interlayer pair tunneling by directly calculating its contribution to superconducting condensation energy.

Quasiparticles and order parameter near quantum phase transition in heavy fermion metals

Energy Technology Data Exchange (ETDEWEB)

Shaginyan, V.R. [Petersburg Nuclear Physics Institute, Russian Academy of Sciences, Gatchina 188300 (Russian Federation) and CTSPS, Clark Atlanta University, Atlanta, GA 30314 (United States)]. E-mail: vrshag@thd.pnpi.spb.ru; Msezane, A.Z. [CTSPS, Clark Atlanta University, Atlanta, GA 30314 (United States); Amusia, M.Ya. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation)

2005-05-02

It is shown that the Landau paradigm based upon both the quasiparticle concept and the notion of the order parameter is valid and can be used to explain the anomalous behavior of the heavy fermion metals near quantum critical points. The understanding of this phenomenon has been problematic largely because of the absence of theoretical guidance. Exploiting this paradigm and the fermion condensation quantum phase transition, we investigate the anomalous behavior of the heavy electron liquid near its critical point at different temperatures and applied magnetic fields. We show that this anomalous behavior is universal and can be used to capture the essential aspects of recent experiments on heavy-fermion metals at low temperatures.

Hannay angle. Yet another symmetry-protected topological order parameter in classical mechanics

International Nuclear Information System (INIS)

Kariyado, Toshikaze; Hatsugai, Yasuhiro

2016-01-01

The topological way of thinking now goes beyond quantum solids, and topological characters of classical mechanical systems obeying Newton's law are attracting current interest. To provide a physical insight into the topological numbers in mechanics, we demonstrate the use of the Hannay angle, a “classical” Berry phase, as a symmetry-protected topological order parameter. The Hannay angle is derived using a canonical transformation that maps Newton's equation to a Schrödinger-type equation, and the condition for the quantization is discussed in connection with the symmetry in mechanics. Also, we demonstrate the use of the Hannay angle for a topological characterization of a spring-mass model focusing on the bulk-edge correspondence. (author)

Analysis and optimization of kinematic pair force in control rod drive mechanism

International Nuclear Information System (INIS)

Sun Zhenguo; Liu Sen; Ran Xiaobing; Dai Changnian; Li Yuezhong

2015-01-01

Function expressions of kinematic pair force with latch dimensions, friction coefficient, link angle and external load was obtained by theoretical analysis, and the expression was verified by the motion analysis software. Key parameters of kinematic pair were confirmed, and their effect trends with force of parts were obtained. They show that the available method of kinematic pair optimization is increasing the space of latch holes. Using the motion analysis software, the forces of parts before and after optimization was compared. The result shows that the forces of parts were improved after the optimization. (authors)

Modeling age differences in effects of pair repetition and proactive interference using a single parameter.

Science.gov (United States)

Stephens, Joseph D W; Overman, Amy A

2018-02-01

In this article, we apply the REM model (Shiffrin & Steyvers, 1997) to age differences in associative memory. Using Criss and Shiffrin's (2005) associative version of REM, we show that in a task with pairs repeated across 2 study lists, older adults' reduced benefit of pair repetition can be produced by a general reduction in the diagnosticity of information stored in memory. This reduction can be modeled similarly well by reducing the overall distinctiveness of memory features, or by reducing the accuracy of memory encoding. We report a new experiment in which pairs are repeated across 3 study lists and extend the model accordingly. Finally, we extend the model to previously reported data using the same task paradigm, in which the use of a high-association strategy introduced proactive interference effects in young adults but not older adults. Reducing the diagnosticity of information in memory also reduces the proactive interference effect. Taken together, the modeling and empirical results reported here are consistent with the claim that some age differences that appear to be specific to associative information can be produced via general degradation of information stored in memory. The REM model provides a useful framework for examining age differences in memory as well as harmonizing seemingly conflicting prior modeling approaches for the associative deficit. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Higher-Order Approximations of Motion of a Nonlinear Oscillator Using the Parameter Expansion Technique

Science.gov (United States)

Ganji, S. S.; Domairry, G.; Davodi, A. G.; Babazadeh, H.; Seyedalizadeh Ganji, S. H.

The main objective of this paper is to apply the parameter expansion technique (a modified Lindstedt-Poincaré method) to calculate the first, second, and third-order approximations of motion of a nonlinear oscillator arising in rigid rod rocking back. The dynamics and frequency of motion of this nonlinear mechanical system are analyzed. A meticulous attention is carried out to the study of the introduced nonlinearity effects on the amplitudes of the oscillatory states and on the bifurcation structures. We examine the synchronization and the frequency of systems using both the strong and special method. Numerical simulations and computer's answers confirm and complement the results obtained by the analytical approach. The approach proposes a choice to overcome the difficulty of computing the periodic behavior of the oscillation problems in engineering. The solutions of this method are compared with the exact ones in order to validate the approach, and assess the accuracy of the solutions. In particular, APL-PM works well for the whole range of oscillation amplitudes and excellent agreement of the approximate frequency with the exact one has been demonstrated. The approximate period derived here is accurate and close to the exact solution. This method has a distinguished feature which makes it simple to use, and also it agrees with the exact solutions for various parameters.

Recoil Induced Room Temperature Stable Frenkel Pairs in a-Hafnium Upon Thermal Neutron Capture

Science.gov (United States)

Butz, Tilman; Das, Satyendra K.; Dey, Chandi C.; Ghoshal, Shamik

2013-11-01

Ultrapure hafnium metal (110 ppm zirconium) was neutron activated with a thermal neutron flux of 6:6 · 1012 cm-2s-1 in order to obtain 181Hf for subsequent time differential perturbed angular correlation (TDPAC) experiments using the nuclear probe 181Hf(β-) 181Ta. Apart from the expected nuclear quadrupole interaction (NQI) signal for a hexagonal close-packed (hcp) metal, three further discrete NQIs were observed with a few percent fraction each. The TDPAC spectra were recorded for up to 11 half lives with extreme statistical accuracy. The fitted parameters vary slightly within the temperature range between 248 K and 373 K. The signals corresponding to the three additional sites completely disappear after `annealing' at 453 K for one minute. Based on the symmetry of the additional NQIs and their temperature dependencies, they are tentatively attributed to Frenkel pairs produced by recoil due to the emission of a prompt 5:694 MeV -ray following thermal neutron capture and reported by the nuclear probe in three different positions. These Frenkel pairs are stable up to at least 373 K.

Extracting rephase-invariant CP and CPT violating parameters from asymmetries of time-ordered integrated rates of correlated decays of entangled mesons

International Nuclear Information System (INIS)

Huang, Zhijie; Shi, Yu.

2012-01-01

We present a general model-independent formalism of measuring CP and CPT violating parameters through time-ordered integrated rates of correlated decays of C=±1 entangled states of neutral pseudoscalar mesons. We give the general formulae of CP and CPT violating parameters in terms of four measurable asymmetries defined for the time-ordered integrated rates, applicable to all kinds of decay product. Two special cases which are often realized in experiments are discussed specifically. (orig.)

Anomalous maximum and minimum for the dissociation of a geminate pair in energetically disordered media

Science.gov (United States)

Govatski, J. A.; da Luz, M. G. E.; Koehler, M.

2015-01-01

We study the geminated pair dissociation probability φ as function of applied electric field and temperature in energetically disordered nD media. Regardless nD, for certain parameters regions φ versus the disorder degree (σ) displays anomalous minimum (maximum) at low (moderate) fields. This behavior is compatible with a transport energy which reaches a maximum and then decreases to negative values as σ increases. Our results explain the temperature dependence of the persistent photoconductivity in C60 single crystals going through order-disorder transitions. They also indicate how an energetic disorder spatial variation may contribute to higher exciton dissociation in multicomponent donor/acceptor systems.

Higgs pair production: choosing benchmarks with cluster analysis

Energy Technology Data Exchange (ETDEWEB)

Carvalho, Alexandra; Dall’Osso, Martino; Dorigo, Tommaso [Dipartimento di Fisica e Astronomia and INFN, Sezione di Padova,Via Marzolo 8, I-35131 Padova (Italy); Goertz, Florian [CERN,1211 Geneva 23 (Switzerland); Gottardo, Carlo A. [Physikalisches Institut, Universität Bonn,Nussallee 12, 53115 Bonn (Germany); Tosi, Mia [CERN,1211 Geneva 23 (Switzerland)

2016-04-20

New physics theories often depend on a large number of free parameters. The phenomenology they predict for fundamental physics processes is in some cases drastically affected by the precise value of those free parameters, while in other cases is left basically invariant at the level of detail experimentally accessible. When designing a strategy for the analysis of experimental data in the search for a signal predicted by a new physics model, it appears advantageous to categorize the parameter space describing the model according to the corresponding kinematical features of the final state. A multi-dimensional test statistic can be used to gauge the degree of similarity in the kinematics predicted by different models; a clustering algorithm using that metric may allow the division of the space into homogeneous regions, each of which can be successfully represented by a benchmark point. Searches targeting those benchmarks are then guaranteed to be sensitive to a large area of the parameter space. In this document we show a practical implementation of the above strategy for the study of non-resonant production of Higgs boson pairs in the context of extensions of the standard model with anomalous couplings of the Higgs bosons. A non-standard value of those couplings may significantly enhance the Higgs boson pair-production cross section, such that the process could be detectable with the data that the LHC will collect in Run 2.

Assessing Local Structure Motifs Using Order Parameters for Motif Recognition, Interstitial Identification, and Diffusion Path Characterization

Directory of Open Access Journals (Sweden)

Nils E. R. Zimmermann

2017-11-01

Full Text Available Structure–property relationships form the basis of many design rules in materials science, including synthesizability and long-term stability of catalysts, control of electrical and optoelectronic behavior in semiconductors, as well as the capacity of and transport properties in cathode materials for rechargeable batteries. The immediate atomic environments (i.e., the first coordination shells of a few atomic sites are often a key factor in achieving a desired property. Some of the most frequently encountered coordination patterns are tetrahedra, octahedra, body and face-centered cubic as well as hexagonal close packed-like environments. Here, we showcase the usefulness of local order parameters to identify these basic structural motifs in inorganic solid materials by developing classification criteria. We introduce a systematic testing framework, the Einstein crystal test rig, that probes the response of order parameters to distortions in perfect motifs to validate our approach. Subsequently, we highlight three important application cases. First, we map basic crystal structure information of a large materials database in an intuitive manner by screening the Materials Project (MP database (61,422 compounds for element-specific motif distributions. Second, we use the structure-motif recognition capabilities to automatically find interstitials in metals, semiconductor, and insulator materials. Our Interstitialcy Finding Tool (InFiT facilitates high-throughput screenings of defect properties. Third, the order parameters are reliable and compact quantitative structure descriptors for characterizing diffusion hops of intercalants as our example of magnesium in MnO2-spinel indicates. Finally, the tools developed in our work are readily and freely available as software implementations in the pymatgen library, and we expect them to be further applied to machine-learning approaches for emerging applications in materials science.

Josephson scanning tunneling microscopy -- a local and direct probe of the superconducting order parameter

Energy Technology Data Exchange (ETDEWEB)

Kimura, Hikari; Dynes, Robert; Barber Jr., Richard. P.; Ono, S.; Ando, Y.

2009-09-01

Direct measurements of the superconducting superfluid on the surface of vacuum-cleaved Bi2Sr2CaCu2O8+delta (BSCCO) samples are reported. These measurements are accomplished via Josephson tunneling into the sample using a novel scanning tunneling microscope (STM) equipped with a superconducting tip. The spatial resolution of the STM of lateral distances less than the superconducting coherence length allows it to reveal local inhomogeneities in the pair wavefunction of the BSCCO. Instrument performance is demonstrated first with Josephson measurements of Pb films followed by the layered superconductor NbSe2. The relevant measurement parameter, the Josephson ICRN product, is discussed within the context of both BCS superconductors and the high transition temperature superconductors. The local relationship between the ICRN product and the quasiparticle density of states (DOS) gap are presented within the context of phase diagrams for BSCCO. Excessive current densities can be produced with these measurements and have been found to alter the local DOS in the BSCCO. Systematic studies of this effect were performed to determine the practical measurement limits for these experiments. Alternative methods for preparation of the BSCCO surface are also discussed.

Parameter Estimation for Thurstone Choice Models

Energy Technology Data Exchange (ETDEWEB)

Vojnovic, Milan [London School of Economics (United Kingdom); Yun, Seyoung [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-04-24

We consider the estimation accuracy of individual strength parameters of a Thurstone choice model when each input observation consists of a choice of one item from a set of two or more items (so called top-1 lists). This model accommodates the well-known choice models such as the Luce choice model for comparison sets of two or more items and the Bradley-Terry model for pair comparisons. We provide a tight characterization of the mean squared error of the maximum likelihood parameter estimator. We also provide similar characterizations for parameter estimators defined by a rank-breaking method, which amounts to deducing one or more pair comparisons from a comparison of two or more items, assuming independence of these pair comparisons, and maximizing a likelihood function derived under these assumptions. We also consider a related binary classification problem where each individual parameter takes value from a set of two possible values and the goal is to correctly classify all items within a prescribed classification error. The results of this paper shed light on how the parameter estimation accuracy depends on given Thurstone choice model and the structure of comparison sets. In particular, we found that for unbiased input comparison sets of a given cardinality, when in expectation each comparison set of given cardinality occurs the same number of times, for a broad class of Thurstone choice models, the mean squared error decreases with the cardinality of comparison sets, but only marginally according to a diminishing returns relation. On the other hand, we found that there exist Thurstone choice models for which the mean squared error of the maximum likelihood parameter estimator can decrease much faster with the cardinality of comparison sets. We report empirical evaluation of some claims and key parameters revealed by theory using both synthetic and real-world input data from some popular sport competitions and online labor platforms.

Hydration of Watson-Crick base pairs and dehydration of Hoogsteen base pairs inducing structural polymorphism under molecular crowding conditions.

Science.gov (United States)

Miyoshi, Daisuke; Nakamura, Kaori; Tateishi-Karimata, Hisae; Ohmichi, Tatsuo; Sugimoto, Naoki

2009-03-18

It has been revealed recently that molecular crowding, which is one of the largest differences between in vivo and in vitro conditions, is a critical factor determining the structure, stability, and function of nucleic acids. However, the effects of molecular crowding on Watson-Crick and Hoogsteen base pairs remain unclear. In order to investigate directly and quantitatively the molecular crowding effects on base pair types in nucleic acids, we designed intramolecular parallel- and antiparallel-stranded DNA duplexes consisting of Hoogsteen and Watson-Crick base pairs, respectively, as well as an intramolecular parallel-stranded triplex containing both types of base pairs. Thermodynamic analyses demonstrated that the values of free energy change at 25 degrees C for Hoogsteen base-pair formations decreased from +1.45 +/- 0.15 to +1.09 +/- 0.13 kcal mol(-1), and from -1.89 +/- 0.13 to -2.71 +/- 0.11 kcal mol(-1) in the intramolecular duplex and triplex, respectively, when the concentration of PEG 200 (polyethylene glycol with average molecular weight 200) increased from 0 to 20 wt %. However, corresponding values for Watson-Crick formation in the duplex and triplex increased from -10.2 +/- 0.2 to -8.7 +/- 0.1 kcal mol(-1), and from -10.8 +/- 0.2 to -9.2 +/- 0.2 kcal mol(-1), respectively. Furthermore, it was revealed that the opposing effects of molecular crowding on the Hoogsteen and Watson-Crick base pairs were due to different behaviors of water molecules binding to the DNA strands.

NNLL momentum-space resummation for stop-pair production at the LHC

International Nuclear Information System (INIS)

Broggio, Alessandro; Ferroglia, Andrea; Neubert, Matthias; Vernazza, Leonardo; Yang, Li Lin

2014-01-01

If supersymmetry near the TeV scale is realized in Nature, the pair production of scalar top squarks is expected to be observable at the Large Hadron Collider. Recently, effective field-theory methods were employed to obtain approximate predictions for the cross section for this process, which include soft-gluon emission effects up to next-to-next-to-leading order (NNLO) in perturbation theory. In this work we employ the same techniques to resum soft-gluon emission effects to all orders in perturbation theory and with next-to-next-to-logarithmic (NNLL) accuracy. We analyze the effects of NNLL resummation on the stop-pair production cross section by obtaining NLO+NNLL predictions in pair invariant mass and one-particle inclusive kinematics. We compare the results of these calculations to the approximate NNLO predictions for the cross sections

NNLL momentum-space resummation for stop-pair production at the LHC

Energy Technology Data Exchange (ETDEWEB)

Broggio, Alessandro [Paul Scherrer Institute,CH-5232 Villigen (Switzerland); Ferroglia, Andrea [New York City College of Technology, The City University of New York,300 Jay Street, Brooklyn, NY 11201 (United States); Neubert, Matthias [PRISMA Cluster of Excellence & Mainz Institut for Theoretical Physics,Johannes Gutenberg University, D-55099 Mainz (Germany); Department of Physics, LEPP, Cornell University,Ithaca, NY 14853 (United States); Vernazza, Leonardo [Dipartimento di Fisica, Università di Torino & INFN - Sezione di Torino,Via P. Giuria 1, I-10125 Torino (Italy); Yang, Li Lin [School of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University, 100871 Beijing (China); Collaborative Innovation Center of Quantum Matter,Beijing (China); Center for High Energy Physics, Peking University,Beijing 100871 (China)

2014-03-12

If supersymmetry near the TeV scale is realized in Nature, the pair production of scalar top squarks is expected to be observable at the Large Hadron Collider. Recently, effective field-theory methods were employed to obtain approximate predictions for the cross section for this process, which include soft-gluon emission effects up to next-to-next-to-leading order (NNLO) in perturbation theory. In this work we employ the same techniques to resum soft-gluon emission effects to all orders in perturbation theory and with next-to-next-to-logarithmic (NNLL) accuracy. We analyze the effects of NNLL resummation on the stop-pair production cross section by obtaining NLO+NNLL predictions in pair invariant mass and one-particle inclusive kinematics. We compare the results of these calculations to the approximate NNLO predictions for the cross sections.

Mass resolution for lepton pairs at Isabelle

International Nuclear Information System (INIS)

Baltay, C.; Paige, F.E.

1978-01-01

Experiments measuring e + e - and μ + μ-pairs will be the principal way of searching at ISABELLE for the Z 0 and for vector mesons made from new heavy quark-antiquark (Q anti Q ) pairs. Although the best possible mass resolution is clearly of benefit in such experiments, excessive resolution would lead to an unnecessarily large detector. It is believed that a mass resolution of a few percent is appropriate in searching both for the Z 0 and for new Q anti Q states. However, there are some interesting experiments which would require much better mass resolution, of order 1/4% FWHM. 9 references

Hadronic production of lepton pairs (experimental)

International Nuclear Information System (INIS)

Boucrot, J.

1980-12-01

Hadonic production of lepton pairs has become a good testground of Q.C.D. The large effects predicted in cross sections and in Psub(T) distributions are seen and may be one of the good indirect proofs of the existence of gluons. Detailed experimental results are available, and clearly it is necessary that higher order Q.C.D. corrections should be estimated

Cd{sub 2}Re{sub 2}O{sub 7}. Temperature dependence of the superconducting order parameter and the effect of quasiparticle self-energy

Energy Technology Data Exchange (ETDEWEB)

Razavi, F.S.; Rohanizadegan, Y.; Hajialamdari, M.; Reedyk, M.; Mitrovic, B. [Department of Physics, Brock University, St. Catharines, ON L2S 3A1 (Canada); Kremer, R.K. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany)

2016-07-01

The temperature dependence and the magnitude of the superconducting order parameter of single crystals of Cd{sub 2}Re{sub 2}O{sub 7} (T{sub c} = 1.02 K) were measured using soft point-contact spectroscopy. The order parameter, Δ(T), increases steeply below the superconducting transition temperature and levels off below ∝ 0.8 K at a value of 0.22(1) meV, about 40 % larger than the BCS value. Our findings indicate the presence of a strong electron-phonon interaction and an enhanced quasiparticle damping and may be related to a possible phase transition within the superconducting region at ∝ 0.8 K. In order to fit the conductance spectra and to extract the order parameter at different temperatures we generalized the Blonder-Tinkham-Klapwijk theory by including the self-energy of the quasiparticles into the Bogoliubov equations. This modification enabled excellent fits of the conductance spectra.

Generalized pairing strategies-a bridge from pairing strategies to colorings

Directory of Open Access Journals (Sweden)

Győrffy Lajos

2016-12-01

Full Text Available In this paper we define a bridge between pairings and colorings of the hypergraphs by introducing a generalization of pairs called t-cakes for t ∈ ℕ, t ≥ 2. For t = 2 the 2-cakes are the same as the well-known pairs of system of distinct representatives, that can be turned to pairing strategies in Maker-Breaker hypergraph games, see Hales and Jewett [12]. The two-colorings are the other extremity of t-cakes, in which the whole ground set of the hypergraph is one big cake that we divide into two parts (color classes. Starting from the pairings (2-cake placement and two-colorings we define the generalized t-cake placements where we pair p elements by q elements (p, q ∈ ℕ, 1 ≤ p, q < t, p + q = t.

Fractional order sliding-mode control based on parameters auto-tuning for velocity control of permanent magnet synchronous motor.

Science.gov (United States)

Zhang, BiTao; Pi, YouGuo; Luo, Ying

2012-09-01

A fractional order sliding mode control (FROSMC) scheme based on parameters auto-tuning for the velocity control of permanent magnet synchronous motor (PMSM) is proposed in this paper. The control law of the proposed F(R)OSMC scheme is designed according to Lyapunov stability theorem. Based on the property of transferring energy with adjustable type in F(R)OSMC, this paper analyzes the chattering phenomenon in classic sliding mode control (SMC) is attenuated with F(R)OSMC system. A fuzzy logic inference scheme (FLIS) is utilized to obtain the gain of switching control. Simulations and experiments demonstrate that the proposed FROSMC not only achieve better control performance with smaller chatting than that with integer order sliding mode control, but also is robust to external load disturbance and parameter variations. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

Charm quark pair correlations with D{sup *}-muon tag at HERA

Energy Technology Data Exchange (ETDEWEB)

Gladkov, D.

2007-07-15

This thesis presents a measurement of double-tagged charm quark pair production via the process ep{yields}e' ccX{yields}e' D*{mu}X' in lepton-proton collisions at HERA, using an integrated luminosity of 114 pb{sup -1} gated by the ZEUS detector in the years 1996-2000. Since the charm quark mass provides a large enough energy scale, the perturbative Quantum Chromo-Dynamics approach can be used to calculate the cross section for charm D*-muon pairs. Using the D*-muon pair to tag the charm quark pair, the measurement is sensitive not only to properties of the leading order hard scattering process but also to the hadronisation and the parton density in the proton as well as higher order effects. Employing the angular and charge correlations between the D* meson and the muon, the fraction of charm events is extracted from the data. Cross sections for charm D*-muon pair production in the visible range of the D* transverse momentum p{sub T}{sup D*}>1.5 GeV, the D* pseudorapidity vertical stroke {eta}{sup D*} vertical stroke <1.5, the muon transverse momentum p{sub T}{sup {mu}}>1.0 GeV and the muon pseudorapidity vertical stroke {eta}{sup {mu}} vertical stroke <2.2 are measured for the inclusive, photoproduction (inelasticity 0.052 GeV{sup 2}) regimes. For the inclusive and photoproduction regimes differential cross sections in various kinematic variables of the D*-muon pair are measured as well. The differential cross sections for the inclusive regime are compared to the leading order plus parton shower MC approach, while the differential cross sections for the photoproduction regime are compared to next-to leading order calculations. The momentum fraction carried by the gluon in the proton is also measured. The possibility of extending the Global Track Trigger of the ZEUS DAQ/trigger system with a forward trigger algorithm is the technical task of this thesis. A forward

An extended Kalman filter approach to non-stationary Bayesian estimation of reduced-order vocal fold model parameters.

Science.gov (United States)

Hadwin, Paul J; Peterson, Sean D

2017-04-01

The Bayesian framework for parameter inference provides a basis from which subject-specific reduced-order vocal fold models can be generated. Previously, it has been shown that a particle filter technique is capable of producing estimates and associated credibility intervals of time-varying reduced-order vocal fold model parameters. However, the particle filter approach is difficult to implement and has a high computational cost, which can be barriers to clinical adoption. This work presents an alternative estimation strategy based upon Kalman filtering aimed at reducing the computational cost of subject-specific model development. The robustness of this approach to Gaussian and non-Gaussian noise is discussed. The extended Kalman filter (EKF) approach is found to perform very well in comparison with the particle filter technique at dramatically lower computational cost. Based upon the test cases explored, the EKF is comparable in terms of accuracy to the particle filter technique when greater than 6000 particles are employed; if less particles are employed, the EKF actually performs better. For comparable levels of accuracy, the solution time is reduced by 2 orders of magnitude when employing the EKF. By virtue of the approximations used in the EKF, however, the credibility intervals tend to be slightly underpredicted.

Programmable trigger for electron pairs in ring image Cherenkov counters

International Nuclear Information System (INIS)

Glab, J.; Baur, R.; Manner, R.

1990-01-01

This paper describes a programmable trigger processor for the recognition of Cherenkov rings in a RICH counter. It identifies open electron pairs and suppresses close conversion and Dalitz pairs within 20 μs. More generally, the system can be used for correlating pixel images with pattern masks in order to locate all relatively well defined patterns of a certain type. The trigger processor consists of a systolic processor array of 160 x 176, i.e., 28,160 identical processing elements (PEs) that filter out open electron pairs, and a pseudo adder array that determines whether there was at least one such pair. The processor array is assembled of 20 x 22 VLSI chips containing 8 x 8 PEs each. The semi-custom chip has been developed in 2 μ CMOS standard cell technology

The Effects of Alkyl Chain Combinations on the Structural and Mechanical Properties of Biomimetic Ion Pair Amphiphile Bilayers

Directory of Open Access Journals (Sweden)

Cheng-hao Chen

2017-10-01

Full Text Available Ion pair amphiphile (IPA, a lipid-like complex composed of a pair of cationic and anionic surfactants, has great potentials in various pharmaceutical applications. In this work, we utilized molecular dynamics (MD simulation to systematically examine the structural and mechanical properties of the biomimetic bilayers consist of alkyltrimethyl-ammonium-alkylsulfate (CmTMA+-CnS− IPAs with various alkyl chain combinations. Our simulations show an intrinsic one-atom offset for the CmTMA+ and CnS− alignment, leading to the asymmetric index definition of ΔC = m − (n + 1. Larger |ΔC| gives rise to higher conformational fluctuations of the alkyl chains with the reduced packing order and mechanical strength. In contrast, increasing the IPA chain length enhances the van der Waals interactions within the bilayer and thus improves the bilayer packing order and mechanical properties. Further elongating the CmTMA+-CnS− alkyl chains to m and n ≥ 12 causes the liquid disorder to gel phase transition of the bilayer at 298 K, with the threshold membrane properties of 0.45 nm2 molecular area, deuterium order parameter value of 0.31, and effective bending rigidity of 20 kBT, etc. The combined results provide molecular insights into the design of biomimetic IPA bilayers with wide structural and mechanical characteristics for various applications.

On the production of low-mass lepton pairs at large transverse momentum

International Nuclear Information System (INIS)

Aurenche, P.; Baier, R.; Fontannaz, M.

1988-03-01

We relate the cross section for the production of low-mass lepton (Drell-Yan) pairs at large transverse momentum to the inclusive prompt (real) photon spectrum. The later one is then evaluated at second order in the QCD coupling constant α s ; predictions are obtained using next-to-leading order quark/gluon densities. Finally, a quantitative comparison with the recent pair data of the UA1 Collaboration is successfully performed. Therefore the considered process is conjectured as an extremely useful probe of the proton structure at small values of x

Pulsar Pair Cascades in Magnetic Fields with Offset Polar Caps

Science.gov (United States)

Harding, Alice K.; Muslimov, Alex G.

2012-01-01

Neutron star magnetic fields may have polar caps (PC) that are offset from the dipole axis, through field-line sweepback near the light cylinder or non-symmetric currents within the star. The effects of such offsets on electron-positron pair cascades are investigated, using simple models of dipole magnetic fields with small distortions that shift the PCs by different amounts or directions. Using a Monte Carlo pair cascade simulation, we explore the changes in the pair spectrum, multiplicity and energy flux across the PC, as well as the trends in pair flux and pair energy flux with spin-down luminosity, L(sub sd). We also give an estimate of the distribution of heating flux from returning positrons on the PC for different offsets. We find that even modest offsets can produce significant increases in pair multiplicity, especially for pulsars that are near or beyond the pair death lines for centered PCs, primarily because of higher accelerating fields. Pair spectra cover several decades in energy, with the spectral range of millisecond pulsars (MSPs) two orders of magnitude higher than for normal pulsars, and PC offsets allow significant extension of all spectra to lower pair energies. We find that the total PC pair luminosity L(sub pair) is proportional to L(sub sd), with L(sub pair) approximates 10(exp -3) L(sub sd) for normal pulsars and L(sub pair) approximates 10(exp -2) L(sub sd) for MSPs. Remarkably, the total PC heating luminosity for even large offsets increases by less than a factor of two, even though the PC area increases by much larger factors, because most of the heating occurs near the magnetic axis.

Combined solitary-wave solution for coupled higher-order nonlinear Schroedinger equations

International Nuclear Information System (INIS)

Tian Jinping; Tian Huiping; Li Zhonghao; Zhou Guosheng

2004-01-01

Coupled nonlinear Schroedinger equations model several interesting physical phenomena. We used a trigonometric function transform method based on a homogeneous balance to solve the coupled higher-order nonlinear Schroedinger equations. We obtained four pairs of exact solitary-wave solutions including a dark and a bright-soliton pair, a bright- and a dark-soliton pair, a bright- and a bright-soliton pair, and the last pair, a combined bright-dark-soliton pair

On the Josephson effect between superconductors in singlet and triplet spin-pairing states

International Nuclear Information System (INIS)

Pals, J.A.; Haeringen, W. van

1977-01-01

An expression is derived for the Josephson current between two weakly coupled superconductors of which one or both have pairs in a spin-triplet state. It is shown that there can be no Josephson effect up to second order in the transition matrix elements between a superconductor with spin-triplet pairs and one with spin-singlet pairs if the coupling between the two superconductors can be described with a spin-conserving tunnel hamiltonian. This is shown to offer a possibility to investigate experimentally whether a particular superconductor has spin-triplet pairs by coupling it weakly to a well-known spin-singlet pairing superconductor. (Auth.)

A Scaffold Analysis Tool Using Mate-Pair Information in Genome Sequencing

Directory of Open Access Journals (Sweden)

Pan-Gyu Kim

2008-01-01

Full Text Available We have developed a Windows-based program, ConPath, as a scaffold analyzer. ConPath constructs scaffolds by ordering and orienting separate sequence contigs by exploiting the mate-pair information between contig-pairs. Our algorithm builds directed graphs from link information and traverses them to find the longest acyclic graphs. Using end read pairs of fixed-sized mate-pair libraries, ConPath determines relative orientations of all contigs, estimates the gap size of each adjacent contig pair, and reports wrong assembly information by validating orientations and gap sizes. We have utilized ConPath in more than 10 microbial genome projects, including Mannheimia succiniciproducens and Vibro vulnificus, where we verified contig assembly and identified several erroneous contigs using the four types of error defined in ConPath. Also, ConPath supports some convenient features and viewers that permit investigation of each contig in detail; these include contig viewer, scaffold viewer, edge information list, mate-pair list, and the printing of complex scaffold structures.

Massive lepton pairs as a prompt photon surrogate

International Nuclear Information System (INIS)

Berger L, Edmond; Gordon E, Lionel; Klasen, Michael

1998-01-01

The authors discuss the transverse momentum distribution for the production of massive lepton-pairs in hadron reactions at fixed target and collider energies within the context of next-to-leading order perturbative quantum chromodynamics. For values of the transverse momentum Q T greater than the pair mass Q, Q T > Q, they show that the differential cross section is dominated by subprocesses initiated by incident gluons. Massive lepton-pair differential cross sections are an advantageous source of constraints on the gluon density, free from the experimental and theoretical complications of photon isolation that beset studies of prompt photon production. They compare calculations with data and provide predictions for the differential cross section as a function of Q T in proton-antiproton reactions at center-of-mass energies of 1.8 TeV, and in proton-nucleon reactions at fixed target and LHC energies

Improved Hybrid Fireworks Algorithm-Based Parameter Optimization in High-Order Sliding Mode Control of Hypersonic Vehicles

Directory of Open Access Journals (Sweden)

Xiaomeng Yin

2018-01-01

Full Text Available With respect to the nonlinear hypersonic vehicle (HV dynamics, achieving a satisfactory tracking control performance under uncertainties is always a challenge. The high-order sliding mode control (HOSMC method with strong robustness has been applied to HVs. However, there are few methods for determining suitable HOSMC parameters for an efficacious control of HV, given that the uncertainties are randomly distributed. In this study, we introduce a hybrid fireworks algorithm- (FWA- based parameter optimization into HV control design to satisfy the design requirements with high probability. First, the complex relation between design parameters and the cost function that evaluates the likelihood of system instability and violation of design requirements is modeled via stochastic robustness analysis. Subsequently, we propose an efficient hybrid FWA to solve the complex optimization problem concerning the uncertainties. The efficiency of the proposed hybrid FWA-based optimization method is demonstrated in the search of the optimal HV controller, in which the proposed method exhibits a better performance when compared with other algorithms.

Scale-free behaviour of amino acid pair interactions in folded proteins

DEFF Research Database (Denmark)

Petersen, Steffen B.; Neves-Petersen, Maria Teresa; Mortensen, Rasmus J.

2012-01-01

The protein structure is a cumulative result of interactions between amino acid residues interacting with each other through space and/or chemical bonds. Despite the large number of high resolution protein structures, the ‘‘protein structure code’’ has not been fully identified. Our manuscript...... presents a novel approach to protein structure analysis in order to identify rules for spatial packing of amino acid pairs in proteins. We have investigated 8706 high resolution non-redundant protein chains and quantified amino acid pair interactions in terms of solvent accessibility, spatial and sequence...... which amino acid paired residues contributed to the cells with a population above 50, pairs of Ala, Ile, Leu and Val dominate the results. This result is statistically highly significant. We postulate that such pairs form ‘‘structural stability points’’ in the protein structure. Our data shows...

Quadratic programming with fuzzy parameters: A membership function approach

International Nuclear Information System (INIS)

Liu, S.-T.

2009-01-01

Quadratic programming has been widely applied to solving real world problems. The conventional quadratic programming model requires the parameters to be known constants. In the real world, however, the parameters are seldom known exactly and have to be estimated. This paper discusses the fuzzy quadratic programming problems where the cost coefficients, constraint coefficients, and right-hand sides are represented by convex fuzzy numbers. Since the parameters in the program are fuzzy numbers, the derived objective value is a fuzzy number as well. Using Zadeh's extension principle, a pair of two-level mathematical programs is formulated to calculate the upper bound and lower bound of the objective values of the fuzzy quadratic program. Based on the duality theorem and by applying the variable transformation technique, the pair of two-level mathematical programs is transformed into a family of conventional one-level quadratic programs. Solving the pair of quadratic programs produces the fuzzy objective values of the problem. An example illustrates method proposed in this paper.

Generation of narrow-band polarization-entangled photon pairs at a rubidium D1 line

International Nuclear Information System (INIS)

Tian Long; Li Shujing; Yuan Haoxiang; Wang Hai

2016-01-01

Using the process of cavity-enhanced spontaneous parametric down-conversion (SPDC), we generate a narrow-band polarization-entangled photon pair resonant on the rubidium (Rb) D1 line (795 nm). The degenerate single-mode photon pair is selected by multiple temperature controlled etalons. The linewidth of generated polarization-entangled photon pairs is 15 MHz which matches the typical atomic memory bandwidth. The measured Bell parameter for the polarization-entangled photons S = 2.73 ± 0.04 which violates the Bell-CHSH inequality by ∼18 standard deviations. The presented entangled photon pair source could be utilized in quantum communication and quantum computing based on quantum memories in atomic ensemble. (author)

English for au pairs the au pair's guide to learning English

CERN Document Server

Curtis, Lucy

2014-01-01

English for Au Pairs has interlinked stories about a group of au pairs new to England. Marta, an 18-year-old from Poland arrives in the UK to work as an au pair. Throughout her year-long stay she has many different experiences - some bad, some good - but with the support of her host family she finds new friends and improves her English. English for Au Pairs offers insight into the joys and difficulties of being an au pair while at the same time reinforcing English language learning through grammar explanations and exercises.

Female bluethroats enhance offspring immunocompetence through extra-pair copulations.

Science.gov (United States)

Johnsen, A; Andersen, V; Sunding, C; Lifjeld, J T

2000-07-20

Female birds frequently copulate with extra-pair males, but the adaptive value of this behaviour is poorly understood. Some studies have suggested that 'good genes' may be involved, where females seek to have their eggs fertilized by high-quality males without receiving any material benefits from them. Nevertheless, it remains to be shown that a genetic benefit is passed on to offspring. Here we report that nestling bluethroats, Luscinia svecica, sired by extra-pair males had a higher T-cell-mediated immune response than their maternal half-siblings raised in the same nest. The difference could not be attributed to nestling body mass, sex or hatching order, but may be an effect of paternal genotype. Extra-pair young were also more immunocompetent than their paternal half-sibs raised in the genetic father's own nest, which indicates an additional effect of maternal genotype. Our results are consistent with the idea that females engage in extra-pair copulations to obtain compatible viability genes, rather than 'good genes' per se.

Wide aperture multipole magnets of the kinematic separator COMBAS. Correcting pair of multipole magnets M3M4 (M5M6) with compensation for higher order aberrations

International Nuclear Information System (INIS)

Artyukh, A.G.; Gridnev, G.F.; Teterev, Yu.G.

1999-01-01

The high-resolving large aperture separator COMBAS has been created and commissioned. The magneto-optical structure of the separator is based on the strong focusing principle. The separator consists of eight wide aperture multipole magnets M1-M8. The magnets M1, M2, M7, M8 forming the 1 st order optics together with some higher order optical corrections and M3-M6 being dedicated to higher order corrections of the chromatic and spherical aberrations at the intermediate and exit foci of the separator. The multipole correctors M3-M6 contain the dipolar, sextupole and octupole components in their magnetic field distributions. It was the use of the rectangular dipoles M3-M6 as carriers of sextupole and octupole field components that let achieve high values of the separator angular and momentum acceptances. Measurements of the magnetic field distributions in the median planes of the pairs of magnets M3M6 (M4M5) have been performed. These measurements allowed one to analyze the magnets manufacturing quality. Based on the analysis, shimming of pole pieces of the pair of magnets M3M6 have been done. Pole surface correcting coils for the magnets M4M5 have been foreseen to compensate for small deviations (within a few percents) of the 2 nd and 3 rd order field components from the design values, which are probable due to manufacturing errors in all the magnets M1-M8. The measured magnetic field distributions are supposed to be used for particle trajectory simulations throughout the entire separator

Analysis model for forecasting extreme temperature using refined rank set pair

Directory of Open Access Journals (Sweden)

Qiao Ling-Xia

2013-01-01

Full Text Available In order to improve the precision of forecasting extreme temperature time series, a refined rank set pair analysis model with a refined rank transformation function is proposed to improve precision of its prediction. The measured values of the annual highest temperature of two China’s cities, Taiyuan and Shijiazhuang, in July are taken to examine the performance of a refined rank set pair model.

Products of Sets: Ordered and Unordered

Indian Academy of Sciences (India)

Abstract. In this article we study the (Cartesian) Productsof sets. As a prelude to it, we examine variousdefinitions offered by different mathematicians tothe concept of an ordered pair. The subtle differencebetween the notions of ordered productsof sets and unordered products of sets is highlighted.

Broken-pair, generalized seniority and interacting boson approximations in a spectroscopic study of Sn nuclei

International Nuclear Information System (INIS)

Bonsignori, K.; Allaart, K.; Egmond, A. van

1983-01-01

A broken-pair study of Sn nuclei is reported in which the model space includes two broken pair states. It is shown that for even Sn nuclei, with a rather simple Gaussian interaction and with single-particle-energies derived from data on odd nuclei, the main features of the excitation spectra up to about 3.5 MeV may be reproduced in this way. The idea of the generalized seniority scheme, that the composition of S-pair operator and that of the D-pair operator may be independent of the total number of pairs, is confirmed by the pair structures which result from energy minimization and diagonalization for each number of pairs separately. A general procedure is described to derive IBA parameters when the valence orbits are nondegenerate. Numerical results for Sn nuclei are given. (U.K.)

Unmatched Projector/Backprojector Pairs: Perturbation and Convergence Analysis

DEFF Research Database (Denmark)

Elfving, Tommy; Hansen, Per Christian

2018-01-01

methods in order to understand the role played by the nonmatch of the matrices. We also study the convergence properties of linear stationary iterations based on unmatched matrix pairs, leading to insight into the behavior of some important row-and column-oriented algebraic iterative methods. We conclude...

Calculation of the decay rate of tachyonic neutrinos against charged-lepton-pair and neutrino-pair Cerenkov radiation

Science.gov (United States)

Jentschura, Ulrich D.; Nándori, István; Ehrlich, Robert

2017-10-01

We consider in detail the calculation of the decay rate of high-energy superluminal neutrinos against (charged) lepton pair Cerenkov radiation, and neutrino pair Cerenkov radiation, i.e., against the decay channels ν \\to ν {e}+ {e}- and ν \\to ν \\overline{ν } ν . Under the hypothesis of a tachyonic nature of neutrinos, these decay channels put constraints on the lifetime of high-energy neutrinos for terrestrial experiments as well as on cosmic scales. For the oncoming neutrino, we use the Lorentz-covariant tachyonic relation {E}ν =\\sqrt{{p}2-{m}ν 2}, where m ν is the tachyonic mass parameter. We derive both threshold conditions as well as on decay and energy loss rates, using the plane-wave fundamental bispinor solutions of the tachyonic Dirac equation. Various intricacies of rest frame versus lab frame calculations are highlighted. The results are compared to the observations of high-energy IceCube neutrinos of cosmological origin.

Reduced-order aeroelastic model for limit-cycle oscillations in vortex-dominated unsteady airfoil flows

Science.gov (United States)

Suresh Babu, Arun Vishnu; Ramesh, Kiran; Gopalarathnam, Ashok

2017-11-01

In previous research, Ramesh et al. (JFM,2014) developed a low-order discrete vortex method for modeling unsteady airfoil flows with intermittent leading edge vortex (LEV) shedding using a leading edge suction parameter (LESP). LEV shedding is initiated using discrete vortices (DVs) whenever the Leading Edge Suction Parameter (LESP) exceeds a critical value. In subsequent research, the method was successfully employed by Ramesh et al. (JFS, 2015) to predict aeroelastic limit-cycle oscillations in airfoil flows dominated by intermittent LEV shedding. When applied to flows that require large number of time steps, the computational cost increases due to the increasing vortex count. In this research, we apply an amalgamation strategy to actively control the DV count, and thereby reduce simulation time. A pair each of LEVs and TEVs are amalgamated at every time step. The ideal pairs for amalgamation are identified based on the requirement that the flowfield in the vicinity of the airfoil is least affected (Spalart, 1988). Instead of placing the amalgamated vortex at the centroid, we place it at an optimal location to ensure that the leading-edge suction and the airfoil bound circulation are conserved. Results of the initial study are promising.

Local density of states and order parameter configurations in layered ferromagnet-superconductor structures

Energy Technology Data Exchange (ETDEWEB)

Halterman, Klaus [Physics and Computational Sciences, Research and Engineering Sciences Department, Naval Air Warfare Center, China Lake, CA 93555 (United States)]. E-mail: klaus.halterman@navy.mil; Valls, Oriol T. [School of Physics and Astronomy and Minnesota Supercomputer Institute, University of Minnesota, Minneapolis, MN 55455 (United States)]. E-mail: otvalls@umn.edu

2005-04-01

We analyze the local density of states (LDOS) of heterostructures consisting of alternating ferromagnet, F, and superconductor, S, layers. We consider structures of the SFS and SFSFSFS type, with thin nanometer scale F and S layers, within the ballistic regime. The spin-splitting effects of the ferromagnet and the mutual coupling between the S regions, yield several nontrivial stable and metastable pair amplitude configurations, and we find that the details of the spatial behavior of the pair amplitude govern the calculated electronic spectra. These are reflected in discernible signatures of the LDOS. The roles that the magnetic exchange energy, interface scattering strength, and the Fermi wavevector mismatch each have on the LDOS for the different allowed junction configurations, are systematically investigated.

Local density of states and order parameter configurations in layered ferromagnet-superconductor structures

International Nuclear Information System (INIS)

Halterman, Klaus; Valls, Oriol T.

2005-01-01

We analyze the local density of states (LDOS) of heterostructures consisting of alternating ferromagnet, F, and superconductor, S, layers. We consider structures of the SFS and SFSFSFS type, with thin nanometer scale F and S layers, within the ballistic regime. The spin-splitting effects of the ferromagnet and the mutual coupling between the S regions, yield several nontrivial stable and metastable pair amplitude configurations, and we find that the details of the spatial behavior of the pair amplitude govern the calculated electronic spectra. These are reflected in discernible signatures of the LDOS. The roles that the magnetic exchange energy, interface scattering strength, and the Fermi wavevector mismatch each have on the LDOS for the different allowed junction configurations, are systematically investigated

Effects of spin-flip scattering on the dynamics of the superconducting order parameter

International Nuclear Information System (INIS)

Aspen, F.E.

1980-06-01

Measurements of the imaginary part of the pair-field susceptibility X'' have been carried out on dirty-limit Al-Er alloy films. Aluminum films with erbium concentrations of up to one atomic percent were incorporated as the low T/sub c/ film of an asymmetric Josephson junction. The excess current I/sub ex/ due to pair tunneling was measured as a function of the bias voltage V and of the magnetic field H, applied in the plane of the junction, at temperatures within 20% of the critical temperature T/sub c/. Comparison to theory was facilitated by noting that X''(ω,k) varies as I/sub ex/(V,H) where the frequency ω and wave-number k are related to V and H via the Josephson relations

Is Routine Ordering of Both Hemoglobin and Hematocrit Justifiable?

Science.gov (United States)

Addison, David J.

1966-01-01

In order to assess the value of routine simultaneous hemoglobin and hematocrit determinations, paired determinations in the following groups were studied: (1) 360 consecutive pairs from the hematology laboratory, (2) 95 pairs on general medical patients, (3) 43 pairs on 10 patients with upper gastrointestinal hemorrhage, and (4) 62 pairs on 10 patients with burns. These values were plotted on scatter diagrams. In the 560 pairs only three disparate determinations were found. It is concluded that, in most clinical situations, determination of the hemoglobin or the hematocrit as a screening procedure provides as much useful information as the simultaneous determination of both. PMID:5296947

A quantum theoretical study of reactions of methyldiazonium ion with DNA base pairs

International Nuclear Information System (INIS)

Shukla, P.K.; Ganapathy, Vinay; Mishra, P.C.

2011-01-01

Graphical abstract: Reactions of methyldiazonium ion at the different sites of the DNA bases in the Watson-Crick GC and AT base pairs were investigated employing density functional and second order Moller-Plesset (MP2) perturbation theories. Display Omitted Highlights: → Methylation of the DNA bases is important as it can cause mutation and cancer. → Methylation reactions of the GC and AT base pairs with CH 3 N 2 + were not studied earlier theoretically. → Experimental observations have been explained using theoretical methods. - Abstract: Methylation of the DNA bases in the Watson-Crick GC and AT base pairs by the methyldiazonium ion was investigated employing density functional and second order Moller-Plesset (MP2) perturbation theories. Methylation at the N3, N7 and O6 sites of guanine, N1, N3 and N7 sites of adenine, O2 and N3 sites of cytosine and the O2 and O4 sites of thymine were considered. The computed reactivities for methylation follow the order N7(guanine) > N3(adenine) > O6(guanine) which is in agreement with experiment. The base pairing in DNA is found to play a significant role with regard to reactivities of the different sites.

Modular Transformations, Order-Chaos Transitions and Pseudo-Random Number Generation

Science.gov (United States)

Bonelli, Antonio; Ruffo, Stefano

Successive pairs of pseudo-random numbers generated by standard linear congruential transformations display ordered patterns of parallel lines. We study the "ordered" and "chaotic" distribution of such pairs by solving the eigenvalue problem for two-dimensional modular transformations over integers. We conjecture that the optimal uniformity for pair distribution is obtained when the slope of linear modular eigenspaces takes the value n opt =maxint (p/√ {p-1}), where p is a prime number. We then propose a new generator of pairs of independent pseudo-random numbers, which realizes an optimal uniform distribution (in the "statistical" sense) of points on the unit square (0, 1] × (0, 1]. The method can be easily generalized to the generation of k-tuples of random numbers (with k>2).

Formation and interference of two pairs of vortex streets

International Nuclear Information System (INIS)

Kamemoto, Kyoji

1976-01-01

A series of theoretical analysis were made on the mechanism of the formation and interference of two pairs of vortex streets appearing behind a pair of two long bars placed perpendicularly to uniform flow. In the first part, the flow model used for this study is explained. It was assumed that two pairs of vortex sheets having the same interval (h) were placed at the distance of g in non-viscous flow. Then small disturbance was given to the flow, and the behavior of the vortex sheets in course of time was analyzed by solving a set of linear simultaneous differential equations. Eight fundamental modes of small displacement were obtained as the independent solutions of the equations. The fundamental modes and the associated parameters are presented. In the second part, a set of non-linear differential equations were derived by substituting the vortex sheets with vortex streets with finite intensity. The set of equations were solved numerically. The results of numerical solutions for various conditions are presented. Main conclusions drawn from this study are that the condition of the existence of two pairs of vortex sheets is g/h >= 1, and that the mutual interference between two pairs of vortex streets becomes conspicuous for g/h <= 2. Some discussions made by other researchers and the author are also presented at the end of this paper. (Aoki, K.)

Quantifying the FIR interaction enhancement in paired galaxies

International Nuclear Information System (INIS)

Xu Cong; Sulentic, J.W.

1990-01-01

We studied the ''Catalogue of Isolated Pairs of Galaxies in the Northern Hemisphere'' by Karachentsev (1972) and a well matched comparison sample taken from the ''Catalogue of Isolated Galaxies'' by Karachentseva (1973) in order to quantify the enhanced FIR emission properties of interacting galaxies. 8 refs, 6 figs

METABOLIC AND BEHAVIORAL PARAMETERS IN NEWBORN PIGLETS IN RELATION TO BIRTH ORDER

Directory of Open Access Journals (Sweden)

H. SĂRĂNDAN

2008-05-01

Full Text Available The experiment had 2 phases:During the first phase 19 sows were monitored during farrowing; the piglets were numbered according to birth order, they were weighed and there were recorded the time each piglet was born and when it first suckled. There was calculated the time from the beginning of the farrowing until the time each piglet was born (TNPP and the time from birth until the first suckle (TPS. A statistical correlation was established between these parameters.During the second experimental phase, for 49 piglets from 5 sows were determined: birth weight, TPS, glycemia at birth (G0 and after the first suckle (G1, rectal temperature at birth (T0 and after the first suckles (T1. This data was statistically analyzed using the Mann-Whitney U test.Respecting the birth order, TPS is shorter for piglets born last (p<0.05. Average TPS was 23.04±2.49 minutes; during this time glycemia rises from 58.35 mg% to 64.35 mg% and rectal temperature drops from 38.58°C to 37.35°C. T0 is positively correlated with G0 (p<0.01 with G1 (p<0.01 and T1 (p<0.01. G0 is highly correlated to G1 (r=0.8855; p=0.

Magnetically-enhanced open string pair production

Science.gov (United States)

Lu, J. X.

2017-12-01

We consider the stringy interaction between two parallel stacks of D3 branes placed at a separation. Each stack of D3 branes in a similar fashion carry an electric flux and a magnetic flux with the two sharing no common field strength index. The interaction amplitude has an imaginary part, giving rise to the Schwinger-like pair production of open strings. We find a significantly enhanced rate of this production when the two electric fluxes are almost identical and the brane separation is on the order of string scale. This enhancement will be largest if the two magnetic fluxes are opposite in direction. This novel enhancement results from the interplay of the non-perturbative Schwinger-type pair production due to the electric flux and the stringy tachyon due to the magnetic flux, and may have realistic physical applications.

Standard-model predictions for W-pair production in electron-positron collisions

International Nuclear Information System (INIS)

Beenakker, W.; Denner, A.

1994-03-01

We review the status of the theoretical predictions for W-pair production in e + e - collisions within the electroweak standard model (SM). We first consider for on-shell W-bosons the lowest-order cross-section within the SM, the general effects of anomalous couplings, the radiative corrections within the SM, and approximations for them. Then we discuss the inclusion of finite-width effects in lowest order and the existing results for radiative corrections to off-shell W-pair production, and we outline the general strategy to calculate radiative corrections within the pole scheme. We summarize the theoretical predictions for the total and partial W-boson widths including radiative corrections and discuss the quality of an improved Born approximation. Finally we provide a general discussion of the structure-function method to calculate large logarithmic higher-order corrections associated with collinear photon radiation. (orig.)

Quasi-stationary states and fermion pair creation from a vacuum in supercritical Coulomb field

Science.gov (United States)

Khalilov, V. R.

2017-12-01

Creation of charged fermion pair from a vacuum in so-called supercritical Coulomb potential is examined for the case when fermions can move only in the same (one) plane. In which case, quantum dynamics of charged massive or massless fermions can be described by the two-dimensional Dirac Hamiltonians with an usual (-a/r) Coulomb potential. These Hamiltonians are singular and require the additional definition in order for them to be treated as self-adjoint quantum-mechanical operators. We construct the self-adjoint two-dimensional Dirac Hamiltonians with a Coulomb potential and determine the quantum-mechanical states for such Hamiltonians in the corresponding Hilbert spaces of square-integrable functions. We determine the scattering amplitude in which the self-adjoint extension parameter is incorporated and then obtain equations implicitly defining possible discrete energy spectra of the self-adjoint Dirac Hamiltonians with a Coulomb potential. It is shown that this quantum system becomes unstable in the presence of a supercritical Coulomb potential which manifests in the appearance of quasi-stationary states in the lower (negative) energy continuum. The energy spectrum of those states is quasi-discrete, consists of broadened levels with widths related to the inverse lifetimes of the quasi-stationary states as well as the probability of creation of charged fermion pair by a supercritical Coulomb field. Explicit analytical expressions for the creation probabilities of charged (massive or massless) fermion pair are obtained in a supercritical Coulomb field.

Higher order structural effects stabilizing the reverse watson-crick guanine-cytosine base pair in functional RNAs

KAUST Repository

Chawla, Mohit; Abdel-Azeim, Safwat; Oliva, Romina; Cavallo, Luigi

2013-01-01

of the Guanine can increase its stability. Herein, we extend our survey and report on other H-bonding interactions that can increase the stability of this base pair. To this aim, we performed a bioinformatics search of the PDB to locate all the occurencies of G

About long range pairing correlations in the Hubbard U-t-t' models

International Nuclear Information System (INIS)

Moreo, A.

1991-01-01

Using a quantum Monte Carlo method the authors measured pair correlation functions with different symmetries as a function of the filling, U/t and t'/t for the Hubbard and U-t-t' models. For the first time the Monte Carlo results are presented for U/t larger than the bandwidth 8t, away from half-filling. D-wave and extended S-wave pairing correlations are enhanced. D-wave pairing is stronger at half-filling but this behavior is reversed when the filling decreases. However, none of the eight pairing correlations that were studied increases as a function of lattice size, which makes the existence of long range superconducting order unlikely. (author). 10 refs.; 5 figs

Experimental congruence of interval scale production from paired comparisons and ranking for image evaluation

Science.gov (United States)

Handley, John C.; Babcock, Jason S.; Pelz, Jeff B.

2003-12-01

Image evaluation tasks are often conducted using paired comparisons or ranking. To elicit interval scales, both methods rely on Thurstone's Law of Comparative Judgment in which objects closer in psychological space are more often confused in preference comparisons by a putative discriminal random process. It is often debated whether paired comparisons and ranking yield the same interval scales. An experiment was conducted to assess scale production using paired comparisons and ranking. For this experiment a Pioneer Plasma Display and Apple Cinema Display were used for stimulus presentation. Observers performed rank order and paired comparisons tasks on both displays. For each of five scenes, six images were created by manipulating attributes such as lightness, chroma, and hue using six different settings. The intention was to simulate the variability from a set of digital cameras or scanners. Nineteen subjects, (5 females, 14 males) ranging from 19-51 years of age participated in this experiment. Using a paired comparison model and a ranking model, scales were estimated for each display and image combination yielding ten scale pairs, ostensibly measuring the same psychological scale. The Bradley-Terry model was used for the paired comparisons data and the Bradley-Terry-Mallows model was used for the ranking data. Each model was fit using maximum likelihood estimation and assessed using likelihood ratio tests. Approximate 95% confidence intervals were also constructed using likelihood ratios. Model fits for paired comparisons were satisfactory for all scales except those from two image/display pairs; the ranking model fit uniformly well on all data sets. Arguing from overlapping confidence intervals, we conclude that paired comparisons and ranking produce no conflicting decisions regarding ultimate ordering of treatment preferences, but paired comparisons yield greater precision at the expense of lack-of-fit.

Isovector pairing effect on the particle-number projection two-proton separation energy

Energy Technology Data Exchange (ETDEWEB)

Mokhtari, Djamila; Kerrouchi, Slimane [Laboratoire de Physique Theorique, Faculte de Physique, Algiers (Algeria); Fellah, Mohamed; Allal, Nassima-Hosni [Laboratoire de Physique Theorique, Faculte de Physique, Algiers (Algeria); Centre de Recherche Nucleaire d' Alger, Comena, Algiers (Algeria)

2009-07-01

The two-proton separation energy is studied by performing a particle-number projection with and without inclusion of the isovector neutron-proton (np) pairing correlations. It is numerically evaluated for even-even rare-earth nuclei such that the np pairing parameter is non-zero. It is shown that the two-proton separation energy values calculated using the two approaches join, for almost all the considered elements, for the highest values of (N-Z). However, the results including the np pairing correlations are closest to the experimental data when available. Moreover, the two methods lead to the same prediction of the two-proton drip-line position, except for the Dysprosium and the Tungsten.

Mahonian pairs

OpenAIRE

Sagan, Bruce E.; Savage, Carla D.

2012-01-01

We introduce the notion of a Mahonian pair. Consider the set, P^*, of all words having the positive integers as alphabet. Given finite subsets S,T of P^*, we say that (S,T) is a Mahonian pair if the distribution of the major index, maj, over S is the same as the distribution of the inversion number, inv, over T. So the well-known fact that maj and inv are equidistributed over the symmetric group, S_n, can be expressed by saying that (S_n,S_n) is a Mahonian pair. We investigate various Mahonia...

Exclusive production of W pairs in CMS

Directory of Open Access Journals (Sweden)

Silveira Da

2014-04-01

Full Text Available We report the results on the search for exclusive production of W pairs in the LHC with data collected by the Compact Muon Solenoid detector in proton-proton collisions at √s = 7 TeV. The analysis comprises the two-photon production of a W pairs, pp → pW+ W− p → p νe± νµ∓ p. Two events are observed in data for pT(ℓ > 4 GeV, |η(ℓ| 20 GeV, in agreement with the standard model prediction of 2.2 ± 0.4 signal events with 0.84 ± 0.15 background events. Moreover, a study of the tail of the lepton pair transverse momentum distribution is performed to search for an evidence of anomalous quartic gauge couplings in the γγ → W+ W− vertex. As no events are observed in data, it results in a model-independent upper limits for the anomalous W quartic gauge couplings aW0,C/Λ2, which are of the order of 10−4.

En route to matter-antimatter pair plasmas

Energy Technology Data Exchange (ETDEWEB)

Stenson, Eve V.; Hergenhahn, Uwe; Paschkowski, Norbert; Saitoh, Haruhiko; Stanja, Juliane [Max Planck Institute for Plasma Physics, Greifswald and Garching (Germany); Niemann, Holger; Sunn Pedersen, Thomas [Max Planck Institute for Plasma Physics, Greifswald and Garching (Germany); Ernst Moritz Arndt University of Greifswald, Greifswald (Germany); Schweikhard, Lutz [Ernst Moritz Arndt University of Greifswald, Greifswald (Germany); Hugenschmidt, Christoph [Technische Universitaet Muenchen, Garching (Germany); Danielson, James R.; Surko, Clifford M. [University of California, San Diego, La Jolla (United States)

2015-05-01

The APEX and PAX projects have as their overarching goal the laboratory creation and confinement of the world's first positron-electron pair plasma. Plasmas of this type have been the subject of hundreds of theoretical investigations and are also believed to play a role in various astrophysical environments. In order to achieve this goal in an experimentally accessible volume (e.g., 10 liters), a record number (≥ 10{sup 10}) of cold (∝ 1 eV) positrons are to be accumulated and combined with a corresponding population of electrons. Notable requirements include a high-intensity positron beam (such as NEPOMUC), a suitable magnetic confinement device for the pair plasma (such as a levitated dipole), high-efficiency tools for bridging the two (i.e., means by which the positrons can be efficiently cooled, trapped, and injected across flux surfaces), and diagnostics not only for the pair plasma, but also for the positron beam and for intermediary non-neutral plasmas. This talk will summarize the project as a whole and recent work by the APEX/PAX team on its various elements.

Convergence of third order correlation energy in atoms and molecules.

Science.gov (United States)

Kahn, Kalju; Granovsky, Alex A; Noga, Jozef

2007-01-30

We have investigated the convergence of third order correlation energy within the hierarchies of correlation consistent basis sets for helium, neon, and water, and for three stationary points of hydrogen peroxide. This analysis confirms that singlet pair energies converge much slower than triplet pair energies. In addition, singlet pair energies with (aug)-cc-pVDZ and (aug)-cc-pVTZ basis sets do not follow a converging trend and energies with three basis sets larger than aug-cc-pVTZ are generally required for reliable extrapolations of third order correlation energies, making so the explicitly correlated R12 calculations preferable.

Proton-antiproton annihilation into a lambdaC-antiLambdaC pair within the generalized parton picture

International Nuclear Information System (INIS)

Goritschnig, A. T.

2009-01-01

The proton-antiproton annihilation into a LambdaC-AntiLambdaC pair is investigated within the handbag approach. It is shown that the dominant dynamical mechanism, characterized by the partonic subprocess anti-u u -> anti-c c, factorizes in the sense that only the subprocess contains highly virtual partons, a gluon to lowest order of perturbative QCD, while the hadronic matrix elements embody only soft scales and can be parameterized in terms of helicity flip and non-flip generalized parton distributions. Modelling these parton distributions by overlaps of light-cone wave functions for the involved baryons were able to predict cross sections and spin correlation parameters for the process of interest. (author) [de

The order parameter and susceptibility of the 3D Ising-like system in an external field near the phase transition point

Directory of Open Access Journals (Sweden)

M.P. Kozlovskii

2010-01-01

Full Text Available The present work is devoted to the investigation of the 3D Ising-like model in the presence of an external field in the vicinity of critical point. The method of collective variables is used. General expressions for the order parameter and susceptibility are calculated as functions of temperature and the external field as well as scaling functions of that are explicitly obtained. The results are compared with the ones obtained within the framework of parametric representation of the equation of state and Monte Carlo simulations. New expression for the exit point from critical regime of the order parameter fluctuations is proposed and used for the calculation.

Baryon pair production in J/ψ decays

International Nuclear Information System (INIS)

Pallin, D.; Ajaltouni, Z.; Falvard, A.

1987-01-01

The decays of 8.6 millions of J/ψ produced at DCI in the DM2 detector are analyzed to measure baryon pair production. Angular distributions for J/ψ→pantip, ΛantiΛ, Σ 0 antiΣ 0 are in good agreement with first order QCD predictions. New measurements are given for the branching ratios of these decays. 16 figs, 3 tab

Charge disproportionation of mixed-valent Cr triggered by Bi lone-pair effect in the A -site-ordered perovskite BiC u3C r4O12

Science.gov (United States)

Etter, Martin; Isobe, Masahiko; Sakurai, Hiroya; Yaresko, Alexander; Dinnebier, Robert E.; Takagi, Hidenori

2018-05-01

A new A -site-ordered perovskite BiC u3C r4O12 is synthesized under a high pressure of 7.7 GPa. A phase transition from a paramagnetic metal to a ferrimagnetic metal is observed at Tc=190 K accompanied with a structural change from cubic to monoclinic. Structural analysis of the low-temperature monoclinic phase reveals that this transition represents a charge disproportionation of C r3.75 + into C r4 + and C r3.5 + . We argue that the asymmetric displacement of Bi caused by a lone-pair effect triggers the formation of a dimeric Cr4+2O5 unit and leads to an ordering of C r4 + and C r3.5 + below the transition.

Phase transition type change in order-order and order-disorder transformations of LaH2+c-like superstoichiometric dihydrides

International Nuclear Information System (INIS)

Ratishvili, I.G.

1999-01-01

Phase transformations in metal-hydrogen systems associated with the ordering processes in the subsystem of interstitial hydrogen atoms are considered. It is shown that in a particular class of superstoichiometric rare-earth dihydrides, where the ordering subsystem is characterized by two long-range-order parameters η 1 , η 2 and the energy parameter p 0 (1) (p) ≤ c ≤ c 0 (2) (p), it becomes discontinuous outside of this region. Dependence of critical concentrations c 0 (1) and c 0 (2) upon the energy parameter p is deduced. It is shown, as well, that there exists a second sequence of critical concentrations, c 1 (1) (p) and c 1 (2) (p), denoting the boundaries between the regions of continuous and discontinuous order-disorder transformations. (orig.)

Tiling array-CGH for the assessment of genomic similarities among synchronous unilateral and bilateral invasive breast cancer tumor pairs

Directory of Open Access Journals (Sweden)

Ringnér Markus

2008-07-01

Full Text Available Abstract Background Today, no objective criteria exist to differentiate between individual primary tumors and intra- or intermammary dissemination respectively, in patients diagnosed with two or more synchronous breast cancers. To elucidate whether these tumors most likely arise through clonal expansion, or whether they represent individual primary tumors is of tumor biological interest and may have clinical implications. In this respect, high resolution genomic profiling may provide a more reliable approach than conventional histopathological and tumor biological factors. Methods 32 K tiling microarray-based comparative genomic hybridization (aCGH was used to explore the genomic similarities among synchronous unilateral and bilateral invasive breast cancer tumor pairs, and was compared with histopathological and tumor biological parameters. Results Based on global copy number profiles and unsupervised hierarchical clustering, five of ten (p = 1.9 × 10-5 unilateral tumor pairs displayed similar genomic profiles within the pair, while only one of eight bilateral tumor pairs (p = 0.29 displayed pair-wise genomic similarities. DNA index, histological type and presence of vessel invasion correlated with the genomic analyses. Conclusion Synchronous unilateral tumor pairs are often genomically similar, while synchronous bilateral tumors most often represent individual primary tumors. However, two independent unilateral primary tumors can develop synchronously and contralateral tumor spread can occur. The presence of an intraductal component is not informative when establishing the independence of two tumors, while vessel invasion, the presence of which was found in clustering tumor pairs but not in tumor pairs that did not cluster together, supports the clustering outcome. Our data suggest that genomically similar unilateral tumor pairs may represent a more aggressive disease that requires the addition of more severe treatment modalities, and

Cross section measurement of the bottom-quark-pair associated top-quark-pair production in the semi-leptonic channel with the CMS experiment

Energy Technology Data Exchange (ETDEWEB)

Heidemann, Fabian; Erdmann, Martin; Fischer, Robert [III. Physikalisches Institut A, RWTH Aachen University (Germany)

2016-07-01

We present a cross section measurement of the top-quark-pair-production with two bottom quarks which is the dominant background process to top-quark-pair associated Higgs Boson production. The semi-leptonic channel of top-quark decays is used due to its combination of a relatively large branching ratio and small QCD contamination. The analysis method relies on Standard Model Monte Carlo simulations of all relevant physics processes. Template distributions are created with Boosted Decision Tree classifiers on the simulated data. Subsequently, the composition of these templates is fitted to the data distribution to obtain the signal strength relative to the Standard Model prediction. A Bayesian interference method is used to perform the fit, in which systematic uncertainties are incorporated as nuisance parameters.

An enquiry into the method of paired comparison: reliability, scaling, and Thurstone's Law of Comparative Judgment

Science.gov (United States)

Thomas C. Brown; George L. Peterson

2009-01-01

The method of paired comparisons is used to measure individuals' preference orderings of items presented to them as discrete binary choices. This paper reviews the theory and application of the paired comparison method, describes a new computer program available for eliciting the choices, and presents an analysis of methods for scaling paired choice data to...

MAJOR-MERGER GALAXY PAIRS AT Z = 0: DUST PROPERTIES AND COMPANION MORPHOLOGY

Energy Technology Data Exchange (ETDEWEB)

Domingue, Donovan L.; Ronca, Joseph; Hill, Emily; Jacques, Allison [Georgia College and State University, CBX 82, Milledgeville, GA 31061 (United States); Cao, Chen [School of Space Science and Physics, Shandong University, Weihai, Weihai, Shandong 264209 (China); Xu, C. Kevin [Infrared Processing and Analysis Center, California Institute of Technology 100-22, Pasadena, CA 91125 (United States); Jarrett, Thomas H. [University of Cape Town, Private Bag X3, Rondebosch 7701, Republic of South Africa (South Africa)

2016-10-01

We present an analysis of dust properties of a sample of close major-merger galaxy pairs selected by K {sub s} magnitude and redshift. The pairs represent the two populations of spiral–spiral (S+S) and mixed morphology spiral–elliptical (S+E). The Code Investigating GALaxy Emission software is used to fit dust models to the Two Micron All Sky Survey, Wide-Field Infrared Survey Explorer , and Herschel flux density measurements, and to derive the parameters describing the polycyclic aromatic hydrocarbons contribution, interstellar radiation field, and photodissociation regions. Model fits verify our previous Spitzer Space Telescope analysis that S+S and S+E pairs do not have the same level of enhancement of star formation and differ in dust composition. The spirals of mixed-morphology galaxy pairs do not exhibit the enhancements in interstellar radiation field and therefore dust temperature for spirals in S+S pairs in contrast to what would be expected according to standard models of gas redistribution due to encounter torques. This suggests the importance of the companion environment/morphology in determining the dust properties of a spiral galaxy in a close major-merger pair.

MAJOR-MERGER GALAXY PAIRS AT Z = 0: DUST PROPERTIES AND COMPANION MORPHOLOGY

International Nuclear Information System (INIS)

Domingue, Donovan L.; Ronca, Joseph; Hill, Emily; Jacques, Allison; Cao, Chen; Xu, C. Kevin; Jarrett, Thomas H.

2016-01-01

We present an analysis of dust properties of a sample of close major-merger galaxy pairs selected by K s magnitude and redshift. The pairs represent the two populations of spiral–spiral (S+S) and mixed morphology spiral–elliptical (S+E). The Code Investigating GALaxy Emission software is used to fit dust models to the Two Micron All Sky Survey, Wide-Field Infrared Survey Explorer , and Herschel flux density measurements, and to derive the parameters describing the polycyclic aromatic hydrocarbons contribution, interstellar radiation field, and photodissociation regions. Model fits verify our previous Spitzer Space Telescope analysis that S+S and S+E pairs do not have the same level of enhancement of star formation and differ in dust composition. The spirals of mixed-morphology galaxy pairs do not exhibit the enhancements in interstellar radiation field and therefore dust temperature for spirals in S+S pairs in contrast to what would be expected according to standard models of gas redistribution due to encounter torques. This suggests the importance of the companion environment/morphology in determining the dust properties of a spiral galaxy in a close major-merger pair.

Preferential solvation, ion pairing, and dynamics of concentrated aqueous solutions of divalent metal nitrate salts

Science.gov (United States)

Yadav, Sushma; Chandra, Amalendu

2017-12-01

We have investigated the characteristics of preferential solvation of ions, structure of solvation shells, ion pairing, and dynamics of aqueous solutions of divalent alkaline-earth metal nitrate salts at varying concentration by means of molecular dynamics simulations. Hydration shell structures and the extent of preferential solvation of the metal and nitrate ions in the solutions are investigated through calculations of radial distribution functions, tetrahedral ordering, and also spatial distribution functions. The Mg2+ ions are found to form solvent separated ion-pairs while the Ca2+ and Sr2+ ions form contact ion pairs with the nitrate ions. These findings are further corroborated by excess coordination numbers calculated through Kirkwood-Buff G factors for different ion-ion and ion-water pairs. The ion-pairing propensity is found to be in the order of Mg(NO3) 2 lead to the presence of substantial dynamical heterogeneity in these solutions of strongly interacting ions. The current study helps us to understand the molecular details of hydration structure, ion pairing, and dynamics of water in the solvation shells and also of ion diffusion in aqueous solutions of divalent metal nitrate salts.

Event generation for next to leading order chargino production at the international linear collider

Energy Technology Data Exchange (ETDEWEB)

Robens, T.

2006-10-15

At the International Linear Collider (ILC), parameters of supersymmetry (SUSY) can be determined with an experimental accuracy matching the precision of next-to-leading order (NLO) and higher-order theoretical predictions. Therefore, these contributions need to be included in the analysis of the parameters. We present a Monte-Carlo event generator for simulating chargino pair production at the ILC at next-to-leading order in the electroweak couplings. We consider two approaches of including photon radiation. A strict fixed-order approach allows for comparison and consistency checks with published semianalytic results in the literature. A version with soft- and hard-collinear resummation of photon radiation, which combines photon resummation with the inclusion of the NLO matrix element for the production process, avoids negative event weights, so the program can simulate physical (unweighted) event samples. Photons are explicitly generated throughout the range where they can be experimentally resolved. In addition, it includes further higher-order corrections unaccounted for by the fixed-order method. Inspecting the dependence on the cutoffs separating the soft and collinear regions, we evaluate the systematic errors due to soft and collinear approximations for NLO and higher-order contributions. In the resummation approach, the residual uncertainty can be brought down to the per-mil level, coinciding with the expected statistical uncertainty at the ILC. We closely investigate the two-photon phase space for the resummation method. We present results for cross sections and event generation for both approaches. (orig.)

Charge and pairing dynamics in the attractive Hubbard model: Mode coupling and the validity of linear-response theory

Science.gov (United States)

Bünemann, Jörg; Seibold, Götz

2017-12-01

Pump-probe experiments have turned out as a powerful tool in order to study the dynamics of competing orders in a large variety of materials. The corresponding analysis of the data often relies on standard linear-response theory generalized to nonequilibrium situations. Here we examine the validity of such an approach for the charge and pairing response of systems with charge-density wave and (or) superconducting (SC) order. Our investigations are based on the attractive Hubbard model which we study within the time-dependent Hartree-Fock approximation. In particular, we calculate the quench and pump-probe dynamics for SC and charge order parameters in order to analyze the frequency spectra and the coupling of the probe field to the specific excitations. Our calculations reveal that the "linear-response assumption" is justified for small to moderate nonequilibrium situations (i.e., pump pulses) in the case of a purely charge-ordered ground state. However, the pump-probe dynamics on top of a superconducting ground state is determined by phase and amplitude modes which get coupled far from the equilibrium state indicating the failure of the linear-response assumption.

Improved contraction schemes for projected entangled pair states

Energy Technology Data Exchange (ETDEWEB)

Lubasch, Michael; Cirac, Juan Ignacio; Banuls, Mari-Carmen [Max Planck Institute of Quantum Optics, Hans-Kopfermann-Strasse 1, 85748 Garching (Germany)

2013-07-01

Projected Entangled Pair States (PEPS) represent the natural generalization of Matrix Product States (MPS) in higher dimensions. The strength of MPS in the numerical simulation of 1D quantum many-body systems is well established, as they are the variational class of states underlying the Density Matrix Renormalization Group and the latter is nowadays considered numerically exact for systems comprising hundreds of quantum particles. In algorithms based on MPS or PEPS, the bond dimension D of the state determines the number of variational parameters and the computational cost. While bond dimensions on the order of hundreds and thousands are feasible with MPS, standard 2D PEPS algorithms are limited to values in the range 2 to 6 due to the much worse scaling of the computational cost with D. Recently, a new algorithm based on an alternative contraction has been proposed that reduces this cost significantly. It resorts to the single-layer picture where the contraction is done in ket and bra separately. We investigate the advantages and disadvantages of this algorithm which can be understood in terms of the PEPS's boundary approximation.

Pairing symmetries of several iron-based superconductor families and some similarities with cuprates and heavy-fermions

Directory of Open Access Journals (Sweden)

Das Tanmoy

2012-03-01

Full Text Available We show that, by using the unit-cell transformation between 1 Fe per unit cell to 2 Fe per unit cell, one can qualitatively understand the pairing symmetry of several families of iron-based superconductors. In iron-pnictides and iron-chalcogenides, the nodeless s±-pairing and the resulting magnetic resonance mode transform nicely between the two unit cells, while retaining all physical properties unchanged. However, when the electron-pocket disappears from the Fermi surface with complete doping in KFe2As2, we find that the unit-cell invariant requirement prohibits the occurrence of s±-pairing symmetry (caused by inter-hole-pocket nesting. However, the intra-pocket nesting is compatible here, which leads to a nodal d-wave pairing. The corresponding Fermi surface topology and the pairing symmetry are similar to Ce-based heavy-fermion superconductors. Furthermore, when the Fermi surface hosts only electron-pockets in KyFe2-xSe2, the inter-electron-pocket nesting induces a nodeless and isotropic d-wave pairing. This situation is analogous to the electron-doped cuprates, where the strong antiferromagnetic order creates similar disconnected electron-pocket Fermi surface, and hence nodeless d-wave pairing appears. The unit-cell transformation in KyFe2-xSe2 exhibits that the d-wave pairing breaks the translational symmetry of the 2 Fe unit cell, and thus cannot be realized unless a vacancy ordering forms to compensate for it. These results are consistent with the coexistence picture of a competing order and nodeless d-wave superconductivity in both cuprates and KyFe1.6Se2.

Electron-positron pair production in ultrarelativistic atomic collisions: 6.4 TeV S16+ with Au, Pd and Al

International Nuclear Information System (INIS)

Datz, S.; Vane, C.R.; Dittner, P.F.; Krause, H.F.; Schuch, R.; Gao, H.; Hutton, R.

1994-01-01

Angular and momentum distributions have been measured for electron-positron pairs created in peripheral collisions of 6.4 TeV bare sulfur ions with thin targets of Al, Pd, and Au. Singly- and doubly-differential cross sections are presented for 1--17 MeV/c electrons and positrons detected independently and in coincidence as pairs. Various physical parameters are deduced from the coincident electron and positron data, including probability distributions for the pair transverse momentum, the pair total energy, and the positron fraction of the pair energy

Taming Radical Pairs in Nanocrystalline Ketones: Photochemical Syn-thesis of Compounds with Vicinal Stereogenic All-Carbon Quaternary Centers.

Science.gov (United States)

Dotson, Jordan J; Perez-Estrada, Salvador; Garcia-Garibay, Miguel A

2018-05-29

Here we describe the use of crystalline ketones to control the fate of the radical pair intermediates generated in the Norrish type I photodecarbonylation reaction to render it a powerful tool in the challenging synthesis of sterically congested carbon-carbon bonds. This methodology makes the synthetically more accessible hexasusbtituted ketones as ideal synthons for the construction of adjacent, all-carbon substituted, stereogenic quaternary stereocenters. We describe here the structural and thermochemical parameters required of the starting ketone in order to react in the solid state. Finally, the scope and scalability of the reaction and its application in the total synthesis of two natural products is described.

Pair correlations in nuclei

International Nuclear Information System (INIS)

Shimizu, Yoshifumi

2009-01-01

Except for the closed shell nuclei, almost all nuclei are in the superconducting state at their ground states. This well-known pair correlation in nuclei causes various interesting phenomena. It is especially to be noted that the pair correlation becomes weak in the excited states of nuclei with high angular momentum, which leads to the pair phase transition to the normal state in the high spin limit. On the other hand, the pair correlation becomes stronger in the nuclei with lower nucleon density than in those with normal density. In the region of neutron halo or skin state of unstable nuclei, this phenomenon is expected to be further enhanced to be observed compared to the ground state of stable nuclei. An overview of those interesting aspects caused via the pair correlation is presented here in the sections titled 'pair correlations in ground states', pair correlations in high spin states' and 'pair correlations in unstable nuclei' focusing on the high spin state. (S. Funahashi)

Experimental many-pairs nonlocality

Science.gov (United States)

Poh, Hou Shun; Cerè, Alessandro; Bancal, Jean-Daniel; Cai, Yu; Sangouard, Nicolas; Scarani, Valerio; Kurtsiefer, Christian

2017-08-01

Collective measurements on large quantum systems together with a majority voting strategy can lead to a violation of the Clauser-Horne-Shimony-Holt Bell inequality. In the presence of many entangled pairs, this violation decreases quickly with the number of pairs and vanishes for some critical pair number that is a function of the noise present in the system. Here we show that a different binning strategy can lead to a more substantial Bell violation when the noise is sufficiently small. Given the relation between the critical pair number and the source noise, we then present an experiment where the critical pair number is used to quantify the quality of a high visibility photon pair source. Our results demonstrate nonlocal correlations using collective measurements operating on clusters of more than 40 photon pairs.

Ion-pairing reversed-phased chromatography/mass spectrometry of heparin

DEFF Research Database (Denmark)

Henriksen, Jens; Roepstorff, Peter; Ringborg, Lene H.

2006-01-01

not well characterised. In order to further characterise such mixtures, two on-line ion-pairing reverse-phased chromatography electrospray ionisation (ESI) mass spectrometry methods have been developed. One of the systems allows the determination of more than 200 components in a medium molecular weight...

Superconducting Fluctuations above T c and pair breaking parameters of two dimensional Niobium Nitride Films

Science.gov (United States)

Shinozaki, B.; Ezaki, S.; Odou, T.; Makise, K.; Asano, T.

2018-03-01

Transport properties have been investigated for the epitaxial superconducting NbN thin films. We analysed the excess conductance σ’ ≡ σ(T) - σN by the sum of the Aslamazov-Larkin (AL) and Maki-Thompson (MT) terms for thermal fluctuations above T c, where the σN ≡1/R sq N is the normal state sheet conductance. We have found that the theoretical expression σ’theo (T) = σ’AL (T) + σ’MT (T,δ) can be well fitted to σ’exp (T) with use of the suitable value of the pair breaking parameter δ in the MT term relating to the inelastic scattering rate 1/τin(T) as δ = πħ/8k B Tτin. The rate 1/τin(T) given by the sum of 1/τfluc(T), 1/τe-e(T) and 1/τe-ph (T) is determined from the analysis of the magneto-conductance Δσ = σ(H) – σ(0) by the sum of AL, MT and the localization terms, where the first, second and third terms correspond to the rate due to the superconducting fluctuation effect, electron-electron and electron-phonon interactions, respectively. The R sq N dependence of δ is expressed by δ = δ0 + αR sq N, where the first term δ0 due to 1/τe-ph (T) and the second term due to the sum of 1/τfluc(T) and 1/τe-e(T). Although we obtained a reasonable value of Debye temperature ΘD ≈630 K from the δ0, the magnitude of the α is about 5 times larger than the theoretical value.

Comparative Analysis of Compatibility Effects on Invigorating Blood Circulation for Cyperi Rhizoma Series of Herb Pairs Using Untargeted Metabolomics

Directory of Open Access Journals (Sweden)

Pei Liu

2017-09-01

Full Text Available The mutual-assistance compatibility of Cyperi Rhizoma (Xiangfu, XF and Angelicae Sinensis Radix (Danggui, DG, Chuanxiong Rhizoma (Chuanxiong, CX, Paeoniae Radix Alba (Baishao, BS, or Corydalis Rhizoma (Yanhusuo, YH, found in a traditional Chinese medicine (TCM named Xiang-Fu-Si-Wu Decoction (XFSWD, can produce synergistic and promoting blood effects. Nowadays, XFSWD has been proved to be effective in activating blood circulation and dissipating blood stasis. However, the role of the herb pairs synergistic effects in the formula were poorly understood. In order to quantitatively assess the compatibility effects of herb pairs, mass spectrometry-based untargeted metabolomics studies were performed. The plasma and urine metabolic profiles of acute blood stasis rats induced by adrenaline hydrochloride and ice water and administered with Cyperi Rhizoma—Angelicae Sinensis Radix (XD, Cyperi Rhizoma—Chuanxiong Rhizoma (XC, Cyperi Rhizoma—Paeoniae Radix Alba (XB, Cyperi Rhizoma—Corydalis Rhizoma (XY were compared. Relative peak area of identified metabolites was calculated and principal component analysis (PCA score plot from the potential markers was used to visualize the overall differences. Then, the metabolites results were used with biochemistry indicators and genes expression values as parameters to quantitatively evaluate the compatibility effects of XF series of herb pairs by PCA and correlation analysis. The collective results indicated that the four XF herb pairs regulated glycerophospholipid metabolism, steroid hormone biosynthesis and arachidonic acid metabolism pathway. XD was more prominent in regulating the blood stasis during the four XF herb pairs. This study demonstrated that metabolomics was a useful tool to efficacy evaluation and compatibility effects of TCM elucidation.

Au pair trajectories

DEFF Research Database (Denmark)

Dalgas, Karina Märcher

2015-01-01

pair-sending families in the Philippines, this dissertation examines the long-term trajectories of these young Filipinas. It shows how the au pairs’ local and transnational family relations develop over time and greatly influence their life trajectories. A focal point of the study is how au pairs...... that Filipina au pairs see their stay abroad as an avenue of personal development and social recognition, I examine how the au pairs re-position themselves within their families at home through migration, and how they navigate between the often conflicting expectations of participation in the sociality......Since 2000, thousands of young Filipino migrants have come to Denmark as au pairs. Officially, they are there to “broaden their cultural horizons” by living temporarily with a Danish host family, but they also conduct domestic labor in exchange for food and money, which allows them to send...

A pure Hubbard model with demonstrable pairing adjacent to the Mott-insulating phase

International Nuclear Information System (INIS)

Champion, J D; Long, M W

2003-01-01

We introduce a Hubbard model on a particular class of geometries, and consider the effect of doping the highly spin-degenerate Mott-insulating state with a microscopic number of holes in the extreme strong-coupling limit. The geometry is quite general, with pairs of atomic sites at each superlattice vertex, and a highly frustrated inter-atomic connectivity: the one-dimensional realization is a chain of edge-sharing tetrahedra. The sole model parameter is the ratio of intra-pair to inter-pair hopping matrix elements. If the intra-pair hopping is negligible then introducing a microscopic number of holes results in a ferromagnetic Nagaoka groundstate. Conversely, if the intra-pair hopping is comparable with the inter-pair hopping then the groundstate is low spin with short-ranged spin correlations. We exactly solve the correlated motion of a pair of holes in such a state and find that, in 1d and 2d, they form a bound pair on a length scale that increases with diminishing binding energy. This result is pertinent to the long-standing problem of hole motion in the CuO 2 planes of the high-temperature superconductors: we have rigorously shown that, on our frustrated geometry, the holes pair up and a short-ranged low-spin state is generated by hole motion alone

Dislocation processes in quasicrystals-Kink-pair formation control or jog-pair formation control

International Nuclear Information System (INIS)

Takeuchi, Shin

2005-01-01

A computer simulation of dislocation in a model quasiperiodic lattice indicates that the dislocation feels a large Peierls potential when oriented in particular directions. For a dislocation with a high Peierls potential, the glide velocity and the climb velocity of the dislocation can be described almost in parallel in terms of the kink-pair formation followed by kink motion and the jog-pair formation followed by jog motion, respectively. The activation enthalpy of the kink-pair formation is the sum of the kink-pair formation enthalpy and the atomic jump activation enthalpy, while the activation enthalpy of the jog-pair formation involves the jog-pair enthalpy and the self-diffusion enthalpy. Since the kink-pair energy can be considerably larger than the jog-pair energy, the climb velocity can be faster than the glide velocity, so that the plastic deformation of quasicrystals can be brought not by dislocation glide but by dislocation climb at high temperatures

Effect of operating parameters on indium (III) ion removal by iron electrocoagulation and evaluation of specific energy consumption

Energy Technology Data Exchange (ETDEWEB)

Chou, Wei-Lung, E-mail: wlchou0388@hotmail.com [Department of Safety, Health and Environmental Engineering, Hungkuang University, Sha-Lu, Taichung 433, Taiwan (China); Wang, Chih-Ta [Department of Safety Health and Environmental Engineering, Chung Hwa University of Medical Technology, Tainan Hsien 717, Taiwan (China); Huang, Kai-Yu [Department of Safety, Health and Environmental Engineering, Hungkuang University, Sha-Lu, Taichung 433, Taiwan (China)

2009-08-15

The aim of this study is to investigate the effects of operating parameters on the specific energy consumption and removal efficiency of synthetic wastewater containing indium (III) ions by electrocoagulation in batch mode using an iron electrode. Several parameters, including different electrode pairs, supporting electrolytes, initial concentration, pH variation, and applied voltage, were investigated. In addition, the effects of applied voltage, supporting electrolyte, and initial concentration on indium (III) ion removal efficiency and specific energy consumption were investigated under the optimum balance of reasonable removal efficiency and relative low energy consumption. Experiment results indicate that a Fe/Al electrode pair is the most efficient choice of the four electrode pairs in terms of energy consumption. The optimum supporting electrolyte concentration, initial concentration, and applied voltage were found to be 100 mg/l NaCl, 20 mg/l, and 20 V, respectively. A higher pH at higher applied voltage (20 or 30 V) enhanced the precipitation of indium (III) ion as insoluble indium hydroxide, which improved the removal efficiency. Results from the indium (III) ion removal kinetics show that the kinetics data fit the pseudo second-order kinetic model well. Finally, the composition of the sludge produced was characterized with energy dispersion spectra (EDS).

Effect of operating parameters on indium (III) ion removal by iron electrocoagulation and evaluation of specific energy consumption

International Nuclear Information System (INIS)

Chou, Wei-Lung; Wang, Chih-Ta; Huang, Kai-Yu

2009-01-01

The aim of this study is to investigate the effects of operating parameters on the specific energy consumption and removal efficiency of synthetic wastewater containing indium (III) ions by electrocoagulation in batch mode using an iron electrode. Several parameters, including different electrode pairs, supporting electrolytes, initial concentration, pH variation, and applied voltage, were investigated. In addition, the effects of applied voltage, supporting electrolyte, and initial concentration on indium (III) ion removal efficiency and specific energy consumption were investigated under the optimum balance of reasonable removal efficiency and relative low energy consumption. Experiment results indicate that a Fe/Al electrode pair is the most efficient choice of the four electrode pairs in terms of energy consumption. The optimum supporting electrolyte concentration, initial concentration, and applied voltage were found to be 100 mg/l NaCl, 20 mg/l, and 20 V, respectively. A higher pH at higher applied voltage (20 or 30 V) enhanced the precipitation of indium (III) ion as insoluble indium hydroxide, which improved the removal efficiency. Results from the indium (III) ion removal kinetics show that the kinetics data fit the pseudo second-order kinetic model well. Finally, the composition of the sludge produced was characterized with energy dispersion spectra (EDS).

High-order dispersion control of 10-petawatt Ti:sapphire laser facility.

Science.gov (United States)

Li, Shuai; Wang, Cheng; Liu, Yanqi; Xu, Yi; Li, Yanyan; Liu, Xingyan; Gan, Zebiao; Yu, Lianghong; Liang, Xiaoyan; Leng, Yuxin; Li, Ruxin

2017-07-24

A grism pair is utilized to control the high-order dispersion of the Shanghai Superintense Ultrafast Lasers Facility, which is a large-scale project aimed at delivering 10-PW laser pulses. We briefly present the characteristics of the laser system and calculate the cumulative B-integral, which determines the nonlinear phase shift influence on material dispersion. Three parameters are selected, grism separation, angle of incidence and slant distance of grating compressor, to determine their optimal values through an iterative searching procedure. Both the numerical and experimental results confirm that the spectral phase distortion is controlled, and the recompressed pulse with a duration of 24 fs is obtained in the single-shot mode. The distributions and stabilities of the pulse duration at different positions of the recompressed beam are also investigated. This approach offers a new feasible solution for the high-order dispersion compensation of femtosecond petawatt laser systems.

Using pairs of physiological models to estimate temporal variation in amphibian body temperature.

Science.gov (United States)

Roznik, Elizabeth A; Alford, Ross A

2014-10-01

Physical models are often used to estimate ectotherm body temperatures, but designing accurate models for amphibians is difficult because they can vary in cutaneous resistance to evaporative water loss. To account for this variability, a recently published technique requires a pair of agar models that mimic amphibians with 0% and 100% resistance to evaporative water loss; the temperatures of these models define the lower and upper boundaries of possible amphibian body temperatures for the location in which they are placed. The goal of our study was to develop a method for using these pairs of models to estimate parameters describing the distributions of body temperatures of frogs under field conditions. We radiotracked green-eyed treefrogs (Litoria serrata) and collected semi-continuous thermal data using both temperature-sensitive radiotransmitters with an automated datalogging receiver, and pairs of agar models placed in frog locations, and we collected discrete thermal data using a non-contact infrared thermometer when frogs were located. We first examined the accuracy of temperature-sensitive transmitters in estimating frog body temperatures by comparing transmitter data with direct temperature measurements taken simultaneously for the same individuals. We then compared parameters (mean, minimum, maximum, standard deviation) characterizing the distributions of temperatures of individual frogs estimated from data collected using each of the three methods. We found strong relationships between thermal parameters estimated from data collected using automated radiotelemetry and both types of thermal models. These relationships were stronger for data collected using automated radiotelemetry and impermeable thermal models, suggesting that in the field, L. serrata has a relatively high resistance to evaporative water loss. Our results demonstrate that placing pairs of thermal models in frog locations can provide accurate estimates of the distributions of temperatures

Fermi-Surface Topological Phase Transition and Horizontal Order-Parameter Nodes in CaFe2As2 Under Pressure

Science.gov (United States)

Gonnelli, R. S.; Daghero, D.; Tortello, M.; Ummarino, G. A.; Bukowski, Z.; Karpinski, J.; Reuvekamp, P. G.; Kremer, R. K.; Profeta, G.; Suzuki, K.; Kuroki, K.

2016-05-01

Iron-based compounds (IBS) display a surprising variety of superconducting properties that seems to arise from the strong sensitivity of these systems to tiny details of the lattice structure. In this respect, systems that become superconducting under pressure, like CaFe2As2, are of particular interest. Here we report on the first directional point-contact Andreev-reflection spectroscopy (PCARS) measurements on CaFe2As2 crystals under quasi-hydrostatic pressure, and on the interpretation of the results using a 3D model for Andreev reflection combined with ab-initio calculations of the Fermi surface (within the density functional theory) and of the order parameter symmetry (within a random-phase-approximation approach in a ten-orbital model). The almost perfect agreement between PCARS results at different pressures and theoretical predictions highlights the intimate connection between the changes in the lattice structure, a topological transition in the holelike Fermi surface sheet, and the emergence on the same sheet of an order parameter with a horizontal node line.

Pair approximation and the OAI mapping in the deformed limit

International Nuclear Information System (INIS)

Yoshinaga, N.

1989-01-01

The pair subspaces - the SD- and SDG-subspaces - are constructed. Eigenstates for a quadrupole force and transition rates for a quadrupole operator are calculated in the single j-shell-model. The SDG-pair approximation is found to be excellent in describing the low-spin states of the ground bands compared to exact shell-model calculations. The fermion interactions are mapped onto the corresponding boson ones using the mapping procedure by Otsuka, Arima and Iachello (OAI). The OAI approximation in zeroth-order fails in reproducing the ground-state energies in the deformed limit. (orig.)

Optimal Decisions for Organ Exchanges in a Kidney Paired Donation Program.

Science.gov (United States)

Li, Yijiang; Song, Peter X-K; Zhou, Yan; Leichtman, Alan B; Rees, Michael A; Kalbfleisch, John D

2014-05-01

The traditional concept of barter exchange in economics has been extended in the modern era to the area of living-donor kidney transplantation, where one incompatible donor-candidate pair is matched to another pair with a complementary incompatibility, such that the donor from one pair gives an organ to a compatible candidate in the other pair and vice versa. Kidney paired donation (KPD) programs provide a unique and important platform for living incompatible donor-candidate pairs to exchange organs in order to achieve mutual benefit. In this paper, we propose novel organ allocation strategies to arrange kidney exchanges under uncertainties with advantages, including (i) allowance for a general utility-based evaluation of potential kidney transplants and an explicit consideration of stochastic features inherent in a KPD program; and (ii) exploitation of possible alternative exchanges when the originally planned allocation cannot be fully executed. This allocation strategy is implemented using an integer programming (IP) formulation, and its implication is assessed via a data-based simulation system by tracking an evolving KPD program over a series of match runs. Extensive simulation studies are provided to illustrate our proposed approach.

Application of Powder Diffraction Methods to the Analysis of Short- and Long-Range Atomic Order in Nanocrystalline Diamond and SiC: The Concept of the Apparent Lattice Parameter (alp)

Science.gov (United States)

Palosz, B.; Grzanka, E.; Gierlotka, S.; Stelmakh, S.; Pielaszek, R.; Bismayer, U.; Weber, H.-P.; Palosz, W.

2003-01-01

Two methods of the analysis of powder diffraction patterns of diamond and SiC nanocrystals are presented: (a) examination of changes of the lattice parameters with diffraction vector Q ('apparent lattice parameter', alp) which refers to Bragg scattering, and (b), examination of changes of inter-atomic distances based on the analysis of the atomic Pair Distribution Function, PDF. Application of these methods was studied based on the theoretical diffraction patterns computed for models of nanocrystals having (i) a perfect crystal lattice, and (ii), a core-shell structure, i.e. constituting a two-phase system. The models are defined by the lattice parameter of the grain core, thickness of the surface shell, and the magnitude and distribution of the strain field in the shell. X-ray and neutron experimental diffraction data of nanocrystalline SiC and diamond powders of the grain diameter from 4 nm up to micrometers were used. The effects of the internal pressure and strain at the grain surface on the structure are discussed based on the experimentally determined dependence of the alp values on the Q-vector, and changes of the interatomic distances with the grain size determined experimentally by the atomic Pair Distribution Function (PDF) analysis. The experimental results lend a strong support to the concept of a two-phase, core and the surface shell structure of nanocrystalline diamond and SiC.

Order parameter free enhanced sampling of the vapor-liquid transition using the generalized replica exchange method.

Science.gov (United States)

Lu, Qing; Kim, Jaegil; Straub, John E

2013-03-14

The generalized Replica Exchange Method (gREM) is extended into the isobaric-isothermal ensemble, and applied to simulate a vapor-liquid phase transition in Lennard-Jones fluids. Merging an optimally designed generalized ensemble sampling with replica exchange, gREM is particularly well suited for the effective simulation of first-order phase transitions characterized by "backbending" in the statistical temperature. While the metastable and unstable states in the vicinity of the first-order phase transition are masked by the enthalpy gap in temperature replica exchange method simulations, they are transformed into stable states through the parameterized effective sampling weights in gREM simulations, and join vapor and liquid phases with a succession of unimodal enthalpy distributions. The enhanced sampling across metastable and unstable states is achieved without the need to identify a "good" order parameter for biased sampling. We performed gREM simulations at various pressures below and near the critical pressure to examine the change in behavior of the vapor-liquid phase transition at different pressures. We observed a crossover from the first-order phase transition at low pressure, characterized by the backbending in the statistical temperature and the "kink" in the Gibbs free energy, to a continuous second-order phase transition near the critical pressure. The controlling mechanisms of nucleation and continuous phase transition are evident and the coexistence properties and phase diagram are found in agreement with literature results.

Dispersion analysis of the Pn -Pn-1DG mixed finite element pair for atmospheric modelling

Science.gov (United States)

Melvin, Thomas

2018-02-01

Mixed finite element methods provide a generalisation of staggered grid finite difference methods with a framework to extend the method to high orders. The ability to generate a high order method is appealing for applications on the kind of quasi-uniform grids that are popular for atmospheric modelling, so that the method retains an acceptable level of accuracy even around special points in the grid. The dispersion properties of such schemes are important to study as they provide insight into the numerical adjustment to imbalance that is an important component in atmospheric modelling. This paper extends the recent analysis of the P2 - P1DG pair, that is a quadratic continuous and linear discontinuous finite element pair, to higher polynomial orders and also spectral element type pairs. In common with the previously studied element pair, and also with other schemes such as the spectral element and discontinuous Galerkin methods, increasing the polynomial order is found to provide a more accurate dispersion relation for the well resolved part of the spectrum but at the cost of a number of unphysical spectral gaps. The effects of these spectral gaps are investigated and shown to have a varying impact depending upon the width of the gap. Finally, the tensor product nature of the finite element spaces is exploited to extend the dispersion analysis into two-dimensions.

Model-order reduction of lumped parameter systems via fractional calculus

Science.gov (United States)

Hollkamp, John P.; Sen, Mihir; Semperlotti, Fabio

2018-04-01

This study investigates the use of fractional order differential models to simulate the dynamic response of non-homogeneous discrete systems and to achieve efficient and accurate model order reduction. The traditional integer order approach to the simulation of non-homogeneous systems dictates the use of numerical solutions and often imposes stringent compromises between accuracy and computational performance. Fractional calculus provides an alternative approach where complex dynamical systems can be modeled with compact fractional equations that not only can still guarantee analytical solutions, but can also enable high levels of order reduction without compromising on accuracy. Different approaches are explored in order to transform the integer order model into a reduced order fractional model able to match the dynamic response of the initial system. Analytical and numerical results show that, under certain conditions, an exact match is possible and the resulting fractional differential models have both a complex and frequency-dependent order of the differential operator. The implications of this type of approach for both model order reduction and model synthesis are discussed.

RNAHelix: computational modeling of nucleic acid structures with Watson-Crick and non-canonical base pairs.

Science.gov (United States)

Bhattacharyya, Dhananjay; Halder, Sukanya; Basu, Sankar; Mukherjee, Debasish; Kumar, Prasun; Bansal, Manju

2017-02-01

Comprehensive analyses of structural features of non-canonical base pairs within a nucleic acid double helix are limited by the availability of a small number of three dimensional structures. Therefore, a procedure for model building of double helices containing any given nucleotide sequence and base pairing information, either canonical or non-canonical, is seriously needed. Here we describe a program RNAHelix, which is an updated version of our widely used software, NUCGEN. The program can regenerate duplexes using the dinucleotide step and base pair orientation parameters for a given double helical DNA or RNA sequence with defined Watson-Crick or non-Watson-Crick base pairs. The original structure and the corresponding regenerated structure of double helices were found to be very close, as indicated by the small RMSD values between positions of the corresponding atoms. Structures of several usual and unusual double helices have been regenerated and compared with their original structures in terms of base pair RMSD, torsion angles and electrostatic potentials and very high agreements have been noted. RNAHelix can also be used to generate a structure with a sequence completely different from an experimentally determined one or to introduce single to multiple mutation, but with the same set of parameters and hence can also be an important tool in homology modeling and study of mutation induced structural changes.

Unmatched Projector/Backprojector Pairs: Perturbation and Convergence Analysis

DEFF Research Database (Denmark)

Elfving, Tommy; Hansen, Per Christian

2018-01-01

are not each other's transpose. Surprisingly, the influence of such errors in algebraic iterative reconstruction methods has received little attention in the literature. The goal of this paper is to perform a rigorous first-order perturbation analysis of the minimization problems underlying the algebraic...... methods in order to understand the role played by the nonmatch of the matrices. We also study the convergence properties of linear stationary iterations based on unmatched matrix pairs, leading to insight into the behavior of some important row-and column-oriented algebraic iterative methods. We conclude...

Determination of supersymmetric parameters with neural networks at the large hadron collider

International Nuclear Information System (INIS)

Bornhauser, Nicki

2013-12-01

The LHC is running and in the near future potentially some signs of new physics are measured. In this thesis it is assumed that the underlying theory of such a signal would be identified and that it is some kind of minimal supersymmetric extension of the Standard Model. Generally, the mapping from the measurable observables onto the parameter values of the supersymmetric theory is unknown. Instead, only the opposite direction is known, i.e. for fixed parameters the measurable observables can be computed with some uncertainties. In this thesis, the ability of artifical neural networks to determine this unknown function is demonstrated. At the end of a training process, the created networks are capable to calculate the parameter values with errors for an existing measurement. To do so, at first a set of mostly counting observables is introduced. In the following, the usefulness of these observables for the determination of supersymmetric parameters is checked. This is done by applying them on 283 pairs of parameter sets of a MSSM with 15 parameters. These pairs were found to be indistinguishable at the LHC by another study, even without the consideration of SM background. It can be shown that 260 of these pairs can be discriminated using the introduced observables. Without systematic errors even all pairs can be distinguished. Also with the consideration of SM background still most pairs can be disentangled (282 without and 237 with systematic errors). This result indicates the usefulness of the observables for the direct parameter determination. The performance of neural networks is investigated for four different parameter regions of the CMSSM. With the right set of observables, the neural network approach generally could also be used for any other (non-supersymmetric) theory. In each region, a reference point with around 1,000 events after cuts should be determined in the context of a LHC with a center of mass energy of 14 TeV and an integrated luminosity of 10 fb

Improving slowness estimate stability and visualization using limited sensor pair correlation on seismic arrays

Science.gov (United States)

Gibbons, Steven J.; Näsholm, S. P.; Ruigrok, E.; Kværna, T.

2018-04-01

Seismic arrays enhance signal detection and parameter estimation by exploiting the time-delays between arriving signals on sensors at nearby locations. Parameter estimates can suffer due to both signal incoherence, with diminished waveform similarity between sensors, and aberration, with time-delays between coherent waveforms poorly represented by the wave-front model. Sensor-to-sensor correlation approaches to parameter estimation have an advantage over direct beamforming approaches in that individual sensor-pairs can be omitted without necessarily omitting entirely the data from each of the sensors involved. Specifically, we can omit correlations between sensors for which signal coherence in an optimal frequency band is anticipated to be poor or for which anomalous time-delays are anticipated. In practice, this usually means omitting correlations between more distant sensors. We present examples from International Monitoring System seismic arrays with poor parameter estimates resulting when classical f-k analysis is performed over the full array aperture. We demonstrate improved estimates and slowness grid displays using correlation beamforming restricted to correlations between sufficiently closely spaced sensors. This limited sensor-pair correlation (LSPC) approach has lower slowness resolution than would ideally be obtained by considering all sensor-pairs. However, this ideal estimate may be unattainable due to incoherence and/or aberration and the LSPC estimate can often exploit all channels, with the associated noise-suppression, while mitigating the complications arising from correlations between very distant sensors. The greatest need for the method is for short-period signals on large aperture arrays although we also demonstrate significant improvement for secondary regional phases on a small aperture array. LSPC can also provide a robust and flexible approach to parameter estimation on three-component seismic arrays.

Top quark pair production and modeling via QCD in CMS

CERN Document Server

Gonzalez Fernandez, Juan Rodrigo

2017-01-01

Measurements of the inclusive and differential top quark pair ($\\textrm{t}\\bar{\\textrm{t}}$) production cross section at centre-of-mass energies of 13 TeV and 5.02 TeV are presented, performed using CMS data collected in 2015 and 2016. The inclusive cross section is measured in the lepton+jets, dilepton and fully hadronic channels. Top quark pair differential cross sections are measured and are given as functions of various kinematic observables of (anti)top quark, the $\\textrm{t}\\bar{\\textrm{t}}$ system, and of the jets and leptons in the final state. Furthermore, the multiplicity and kinematic distributions of the additional jets produced in $\\textrm{t}\\bar{\\textrm{t}}$ events are also investigated and its modeling is compared for several generators. A new tune of parameters is developed for some of the generators. In addition, first measurements of top quark pair production with additional b quarks in the final state are presented. Furthermore, searches for four top quark production in CMS are also present...

Unstable Modes and Order Parameters of Bistable Signaling Pathways at Saddle-Node Bifurcations: A Theoretical Study Based on Synergetics

Directory of Open Access Journals (Sweden)

Till D. Frank

2016-01-01

Full Text Available Mathematical modeling has become an indispensable part of systems biology which is a discipline that has become increasingly popular in recent years. In this context, our understanding of bistable signaling pathways in terms of mathematical modeling is of particular importance because such bistable components perform crucial functions in living cells. Bistable signaling pathways can act as switches or memory functions and can determine cell fate. In the present study, properties of mathematical models of bistable signaling pathways are examined from the perspective of synergetics, a theory of self-organization and pattern formation founded by Hermann Haken. At the heart of synergetics is the concept of so-called unstable modes or order parameters that determine the behavior of systems as a whole close to bifurcation points. How to determine these order parameters for bistable signaling pathways at saddle-node bifurcation points is shown. The procedure is outlined in general and an explicit example is worked out in detail.

Existence of positive solutions for nonlocal second-order boundary value problem with variable parameter in Banach spaces

Directory of Open Access Journals (Sweden)

Zhang Peiguo

2011-01-01

Full Text Available Abstract By obtaining intervals of the parameter λ, this article investigates the existence of a positive solution for a class of nonlinear boundary value problems of second-order differential equations with integral boundary conditions in abstract spaces. The arguments are based upon a specially constructed cone and the fixed point theory in cone for a strict set contraction operator. MSC: 34B15; 34B16.

AudioPairBank: Towards A Large-Scale Tag-Pair-Based Audio Content Analysis

OpenAIRE

Sager, Sebastian; Elizalde, Benjamin; Borth, Damian; Schulze, Christian; Raj, Bhiksha; Lane, Ian

2016-01-01

Recently, sound recognition has been used to identify sounds, such as car and river. However, sounds have nuances that may be better described by adjective-noun pairs such as slow car, and verb-noun pairs such as flying insects, which are under explored. Therefore, in this work we investigate the relation between audio content and both adjective-noun pairs and verb-noun pairs. Due to the lack of datasets with these kinds of annotations, we collected and processed the AudioPairBank corpus cons...

Estimating Eulerian spectra from pairs of drifters

Science.gov (United States)

LaCasce, Joe

2017-04-01

GPS-tracked surface drifters offer the possibility of sampling energetic variations at the ocean surface on scales of only 10s of meters, much less than that resolved by satellite. Here we investigate whether velocity differences between pairs of drifters can be used to estimate kinetic energy spectra. Theoretical relations between the spectrum and the second-order longitudinal structure function for 2D non-divergent flow are derived. The structure function is a natural statistic for particle pairs and is easily calculated. However it integrates contributions across wavenumber, and this tends to obscure the spectral dependencies when turbulent inertial ranges are of finite extent. Nevertheless, the transform from spectrum to structure function is robust, as illustrated with Eulerian data collected from aircraft. The inverse transform, from structure function to spectrum, is much less robust, yielding poor results in particular at large wavenumbers. This occurs because the transform involves a filter function which magnifies contributions from large pair separations, which tend to be noisy. Fitting the structure function to a polynomial improves the spectral estimate, but not sufficiently to distinguish correct inertial range dependencies. Thus with Lagrangian data, it is appears preferable to focus on structure functions, despite their shortcomings.

On a method for constructing the Lax pairs for nonlinear integrable equations

International Nuclear Information System (INIS)

Habibullin, I T; Poptsova, M N; Khakimova, A R

2016-01-01

We suggest a direct algorithm for searching the Lax pairs for nonlinear integrable equations. It is effective for both continuous and discrete models. The first operator of the Lax pair corresponding to a given nonlinear equation is found immediately, coinciding with the linearization of the considered nonlinear equation. The second one is obtained as an invariant manifold to the linearized equation. A surprisingly simple relation between the second operator of the Lax pair and the recursion operator is discussed: the recursion operator can immediately be found from the Lax pair. Examples considered in the article are convincing evidence that the found Lax pairs differ from the classical ones. The examples also show that the suggested objects are true Lax pairs which allow the construction of infinite series of conservation laws and hierarchies of higher symmetries. In the case of the hyperbolic type partial differential equation our algorithm is slightly modified; in order to construct the Lax pairs from the invariant manifolds we use the cutting off conditions for the corresponding infinite Laplace sequence. The efficiency of the method is illustrated by application to some equations given in the Svinolupov–Sokolov classification list for which the Lax pairs and the recursion operators have not been found earlier. (paper)

Higher-Order Generalized Invexity in Control Problems

Directory of Open Access Journals (Sweden)

S. K. Padhan

2011-01-01

Full Text Available We introduce a higher-order duality (Mangasarian type and Mond-Weir type for the control problem. Under the higher-order generalized invexity assumptions on the functions that compose the primal problems, higher-order duality results (weak duality, strong duality, and converse duality are derived for these pair of problems. Also, we establish few examples in support of our investigation.

Pairing correlations. II. Microscopic analysis of odd-even mass staggering in nuclei

International Nuclear Information System (INIS)

Duguet, T.; Bonche, P.; Heenen, P.-H.; Meyer, J.

2002-01-01

The odd-even mass staggering in nuclei is analyzed in the context of self-consistent mean-field calculations, for spherical as well as for deformed nuclei. For these nuclei, the respective merits of the energy differences Δ (3) and Δ (5) to extract both the pairing gap and the time-reversal symmetry breaking effect at the same time are extensively discussed. The usual mass formula Δ (3) is shown to contain additional mean-field contributions when realistic pairing is used in the calculation. A simple tool is proposed in order to remove the time-reversal symmetry breaking effects from Δ (5) . Extended comparisons with the odd-even mass staggering obtained in the zero-pairing limit (schematic model and self-consistent calculations) show the nonperturbative contribution of pairing correlations on this observable

Base pair probability estimates improve the prediction accuracy of RNA non-canonical base pairs.

Directory of Open Access Journals (Sweden)

Michael F Sloma

2017-11-01

Full Text Available Prediction of RNA tertiary structure from sequence is an important problem, but generating accurate structure models for even short sequences remains difficult. Predictions of RNA tertiary structure tend to be least accurate in loop regions, where non-canonical pairs are important for determining the details of structure. Non-canonical pairs can be predicted using a knowledge-based model of structure that scores nucleotide cyclic motifs, or NCMs. In this work, a partition function algorithm is introduced that allows the estimation of base pairing probabilities for both canonical and non-canonical interactions. Pairs that are predicted to be probable are more likely to be found in the true structure than pairs of lower probability. Pair probability estimates can be further improved by predicting the structure conserved across multiple homologous sequences using the TurboFold algorithm. These pairing probabilities, used in concert with prior knowledge of the canonical secondary structure, allow accurate inference of non-canonical pairs, an important step towards accurate prediction of the full tertiary structure. Software to predict non-canonical base pairs and pairing probabilities is now provided as part of the RNAstructure software package.

Base pair probability estimates improve the prediction accuracy of RNA non-canonical base pairs.

Science.gov (United States)

Sloma, Michael F; Mathews, David H

2017-11-01

Prediction of RNA tertiary structure from sequence is an important problem, but generating accurate structure models for even short sequences remains difficult. Predictions of RNA tertiary structure tend to be least accurate in loop regions, where non-canonical pairs are important for determining the details of structure. Non-canonical pairs can be predicted using a knowledge-based model of structure that scores nucleotide cyclic motifs, or NCMs. In this work, a partition function algorithm is introduced that allows the estimation of base pairing probabilities for both canonical and non-canonical interactions. Pairs that are predicted to be probable are more likely to be found in the true structure than pairs of lower probability. Pair probability estimates can be further improved by predicting the structure conserved across multiple homologous sequences using the TurboFold algorithm. These pairing probabilities, used in concert with prior knowledge of the canonical secondary structure, allow accurate inference of non-canonical pairs, an important step towards accurate prediction of the full tertiary structure. Software to predict non-canonical base pairs and pairing probabilities is now provided as part of the RNAstructure software package.

RNA-PAIRS: RNA probabilistic assignment of imino resonance shifts

International Nuclear Information System (INIS)

Bahrami, Arash; Clos, Lawrence J.; Markley, John L.; Butcher, Samuel E.; Eghbalnia, Hamid R.

2012-01-01

The significant biological role of RNA has further highlighted the need for improving the accuracy, efficiency and the reach of methods for investigating RNA structure and function. Nuclear magnetic resonance (NMR) spectroscopy is vital to furthering the goals of RNA structural biology because of its distinctive capabilities. However, the dispersion pattern in the NMR spectra of RNA makes automated resonance assignment, a key step in NMR investigation of biomolecules, remarkably challenging. Herein we present RNA Probabilistic Assignment of Imino Resonance Shifts (RNA-PAIRS), a method for the automated assignment of RNA imino resonances with synchronized verification and correction of predicted secondary structure. RNA-PAIRS represents an advance in modeling the assignment paradigm because it seeds the probabilistic network for assignment with experimental NMR data, and predicted RNA secondary structure, simultaneously and from the start. Subsequently, RNA-PAIRS sets in motion a dynamic network that reverberates between predictions and experimental evidence in order to reconcile and rectify resonance assignments and secondary structure information. The procedure is halted when assignments and base-parings are deemed to be most consistent with observed crosspeaks. The current implementation of RNA-PAIRS uses an initial peak list derived from proton-nitrogen heteronuclear multiple quantum correlation ( 1 H– 15 N 2D HMQC) and proton–proton nuclear Overhauser enhancement spectroscopy ( 1 H– 1 H 2D NOESY) experiments. We have evaluated the performance of RNA-PAIRS by using it to analyze NMR datasets from 26 previously studied RNAs, including a 111-nucleotide complex. For moderately sized RNA molecules, and over a range of comparatively complex structural motifs, the average assignment accuracy exceeds 90%, while the average base pair prediction accuracy exceeded 93%. RNA-PAIRS yielded accurate assignments and base pairings consistent with imino resonances for a

RNA-PAIRS: RNA probabilistic assignment of imino resonance shifts

Energy Technology Data Exchange (ETDEWEB)

Bahrami, Arash; Clos, Lawrence J.; Markley, John L.; Butcher, Samuel E. [National Magnetic Resonance Facility at Madison (United States); Eghbalnia, Hamid R., E-mail: eghbalhd@uc.edu [University of Cincinnati, Department of Molecular and Cellular Physiology (United States)

2012-04-15

The significant biological role of RNA has further highlighted the need for improving the accuracy, efficiency and the reach of methods for investigating RNA structure and function. Nuclear magnetic resonance (NMR) spectroscopy is vital to furthering the goals of RNA structural biology because of its distinctive capabilities. However, the dispersion pattern in the NMR spectra of RNA makes automated resonance assignment, a key step in NMR investigation of biomolecules, remarkably challenging. Herein we present RNA Probabilistic Assignment of Imino Resonance Shifts (RNA-PAIRS), a method for the automated assignment of RNA imino resonances with synchronized verification and correction of predicted secondary structure. RNA-PAIRS represents an advance in modeling the assignment paradigm because it seeds the probabilistic network for assignment with experimental NMR data, and predicted RNA secondary structure, simultaneously and from the start. Subsequently, RNA-PAIRS sets in motion a dynamic network that reverberates between predictions and experimental evidence in order to reconcile and rectify resonance assignments and secondary structure information. The procedure is halted when assignments and base-parings are deemed to be most consistent with observed crosspeaks. The current implementation of RNA-PAIRS uses an initial peak list derived from proton-nitrogen heteronuclear multiple quantum correlation ({sup 1}H-{sup 15}N 2D HMQC) and proton-proton nuclear Overhauser enhancement spectroscopy ({sup 1}H-{sup 1}H 2D NOESY) experiments. We have evaluated the performance of RNA-PAIRS by using it to analyze NMR datasets from 26 previously studied RNAs, including a 111-nucleotide complex. For moderately sized RNA molecules, and over a range of comparatively complex structural motifs, the average assignment accuracy exceeds 90%, while the average base pair prediction accuracy exceeded 93%. RNA-PAIRS yielded accurate assignments and base pairings consistent with imino