Ascierto, Paolo A; Agarwala, Sanjiv; Botti, Gerardo; Cesano, Alessandra; Ciliberto, Gennaro; Davies, Michael A; Demaria, Sandra; Dummer, Reinhard; Eggermont, Alexander M; Ferrone, Soldano; Fu, Yang Xin; Gajewski, Thomas F; Garbe, Claus; Huber, Veronica; Khleif, Samir; Krauthammer, Michael; Lo, Roger S; Masucci, Giuseppe; Palmieri, Giuseppe; Postow, Michael; Puzanov, Igor; Silk, Ann; Spranger, Stefani; Stroncek, David F; Tarhini, Ahmad; Taube, Janis M; Testori, Alessandro; Wang, Ena; Wargo, Jennifer A; Yee, Cassian; Zarour, Hassane; Zitvogel, Laurence; Fox, Bernard A; Mozzillo, Nicola; Marincola, Francesco M; Thurin, Magdalena
2016-11-15
The sixth "Melanoma Bridge Meeting" took place in Naples, Italy, December 1st-4th, 2015. The four sessions at this meeting were focused on: (1) molecular and immune advances; (2) combination therapies; (3) news in immunotherapy; and 4) tumor microenvironment and biomarkers. Recent advances in tumor biology and immunology has led to the development of new targeted and immunotherapeutic agents that prolong progression-free survival (PFS) and overall survival (OS) of cancer patients. Immunotherapies in particular have emerged as highly successful approaches to treat patients with cancer including melanoma, non-small cell lung cancer (NSCLC), renal cell carcinoma (RCC), bladder cancer, and Hodgkin's disease. Specifically, many clinical successes have been using checkpoint receptor blockade, including T cell inhibitory receptors such as cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and the programmed cell death-1 (PD-1) and its ligand PD-L1. Despite demonstrated successes, responses to immunotherapy interventions occur only in a minority of patients. Attempts are being made to improve responses to immunotherapy by developing biomarkers. Optimizing biomarkers for immunotherapy could help properly select patients for treatment and help to monitor response, progression and resistance that are critical challenges for the immuno-oncology (IO) field. Importantly, biomarkers could help to design rational combination therapies. In addition, biomarkers may help to define mechanism of action of different agents, dose selection and to sequence drug combinations. However, biomarkers and assays development to guide cancer immunotherapy is highly challenging for several reasons: (i) multiplicity of immunotherapy agents with different mechanisms of action including immunotherapies that target activating and inhibitory T cell receptors (e.g., CTLA-4, PD-1, etc.); adoptive T cell therapies that include tissue infiltrating lymphocytes (TILs), chimeric antigen receptors (CARs), and
Eyenga, V C; Ndoumbe, A; Eloundou, N J
2008-04-01
Neurosurgery remains a very marginal activity in sub-Saharan Africa. In this part of the world which counts nearly 40 countries, some do not have a single neurosurgeon, some have one to five, the number of ten neurosurgeons per country remaining an exception! In its concern of popularizing and of developing neurosurgery worldwide, the WFNS organized an international course in Africa, October 2007 2nd-3rd in Yaoundé (Cameroon). The Cameroon Neurosurgery Society (CNS) took this opportunity to organize its very first congress in the presence of the WFNS delegation from October 1st to 4th, 2007. The joint meeting with the WFNS was baptized the "African Week of Neurosurgery". This special event was a first in sub-Saharan Africa. The delegation of the WFNS, led by Professor J. Brotchi (Belgium) President of the WFNS, was made up of Professors A. Sousa (Brazil), Mr. Choux (France), N. Tribolet (Swiss), M. Arraez (Spain), A. Bricolo (Italy), A. Kamlichi (Morocco), G. Dechambenoit (France), K. Kalangu (Zimbabwe). Twenty three neurosurgeons coming from nine African countries (Cameroon, Nigeria, Gabon, Congo, Niger, Burkina Faso, Ivory Coast, Senegal, and Guinea) took an active part in work. The scientific success of this event led to the creation of the "Association of Neurological Surgeons of Africa (ANSA)" which will be the WFNS-Africa interface in order to insure the development of neurosurgery in Africa.
Quantum correlations with no causal order
Oreshkov, Ognyan; Costa, Fabio; Brukner, Časlav
2012-01-01
The idea that events obey a definite causal order is deeply rooted in our understanding of the world and at the basis of the very notion of time. But where does causal order come from, and is it a necessary property of nature? Here, we address these questions from the standpoint of quantum mechanics in a new framework for multipartite correlations that does not assume a pre-defined global causal structure but only the validity of quantum mechanics locally. All known situations that respect causal order, including space-like and time-like separated experiments, are captured by this framework in a unified way. Surprisingly, we find correlations that cannot be understood in terms of definite causal order. These correlations violate a 'causal inequality' that is satisfied by all space-like and time-like correlations. We further show that in a classical limit causal order always arises, which suggests that space-time may emerge from a more fundamental structure in a quantum-to-classical transition. PMID:23033068
Higher order correlations of IRAS galaxies
NASA Technical Reports Server (NTRS)
Meiksin, Avery; Szapudi, Istvan; Szalay, Alexander
1992-01-01
The higher order irreducible angular correlation functions are derived up to the eight-point function, for a sample of 4654 IRAS galaxies, flux-limited at 1.2 Jy in the 60 microns band. The correlations are generally found to be somewhat weaker than those for the optically selected galaxies, consistent with the visual impression of looser clusters in the IRAS sample. It is found that the N-point correlation functions can be expressed as the symmetric sum of products of N - 1 two-point functions, although the correlations above the four-point function are consistent with zero. The coefficients are consistent with the hierarchical clustering scenario as modeled by Hamilton and by Schaeffer.
Polarization-correlation optical microscopy of anisotropic biological layers
NASA Astrophysics Data System (ADS)
Ushenko, A. G.; Dubolazov, A. V.; Ushenko, V. A.; Ushenko, Yu. A.; Sakhnovskiy, M. Y.; Balazyuk, V. N.; Khukhlina, O.; Viligorska, K.; Bykov, A.; Doronin, A.; Meglinski, I.
2016-09-01
The theoretical background of azimuthally stable method of Jones-matrix mapping of histological sections of biopsy of myocardium tissue on the basis of spatial frequency selection of the mechanisms of linear and circular birefringence is presented. The diagnostic application of a new correlation parameter - complex degree of mutual anisotropy - is analytically substantiated. The method of measuring coordinate distributions of complex degree of mutual anisotropy with further spatial filtration of their high- and low-frequency components is developed. The interconnections of such distributions with parameters of linear and circular birefringence of myocardium tissue histological sections are found. The comparative results of measuring the coordinate distributions of complex degree of mutual anisotropy formed by fibrillar networks of myosin fibrils of myocardium tissue of different necrotic states - dead due to coronary heart disease and acute coronary insufficiency are shown. The values and ranges of change of the statistical (moments of the 1st - 4th order) parameters of complex degree of mutual anisotropy coordinate distributions are studied. The objective criteria of differentiation of cause of death are determined.
High-order correlation of chaotic bosons and fermions
NASA Astrophysics Data System (ADS)
Liu, Hong-Chao
2016-08-01
We theoretically study the high-order correlation functions of chaotic bosons and fermions. Based on the different parity of the Stirling number, the products of the first-order correlation functions are well classified and employed to represent the high-order correlation function. The correlation of bosons conduces a bunching effect, which will be enhanced as order N increases. Different from bosons, the anticommutation relation of fermions leads to the parity of the Stirling number, which thereby results in a mixture of bunching and antibunching behaviors in high-order correlation. By further investigating third-order ghost diffraction and ghost imaging, the differences between the high-order correlations of bosons and fermions are discussed in detail. A larger N will dramatically improve the ghost image quality for bosons, but a good strategy should be carefully chosen for the fermionic ghost imaging process due to its complex correlation components.
Second-order centrality correlation in scale-free networks
NASA Astrophysics Data System (ADS)
Lv, Meilei; Guo, Xinling; Chen, Jiaquan; Lu, Zhe-Ming; Nie, Tingyuan
2015-02-01
Scale-free networks in which the degree displays a power-law distribution can be classified into assortative, disassortative, and neutral networks according to their degree-degree correlation. The second-order centrality proposed in a distributed computation manner is quick-calculated and accurate to identify critical nodes. We explore the second-order centrality correlation (SOC) for each type of the scale-free networks. The SOC-SOC correlation in assortative network and neutral network behaves similarly to the degree-degree correlation, while it behaves an apparent difference in disassortative networks. Experiments show that the invulnerability of most of scale-free networks behaves similarly under the node removal ordering by SOC centrality and degree centrality, respectively. The netscience network and the Yeast network behave a little differently because they are native disconnecting networks.
NASA Astrophysics Data System (ADS)
Marchuk, Yu F.; Fediv, O. I.; Ivashchuk, I. O.; Andriychuk, D. R.
2012-01-01
The principles of optical modeling of human bile polycrystalline structure are described. The main types of polycrystalline structures are detailed. It has been proposed and founded the scenarios of formation of bile microscopic images polarization structure in coherent radiation. The results of investigating the interrelation between statistical moments of the 1st-4th order are presented that characterize the coordinate distributions of intensity of laser images of bile smears of cholelithiasis patients in combination with other pathologies. The diagnostic criteria of the cholelithiasis nascency and its severity degree differentiation are determined.
NASA Astrophysics Data System (ADS)
Marchuk, Yu F.; Fediv, O. I.; Ivashchuk, I. O.; Andriychuk, D. R.
2011-09-01
The principles of optical modeling of human bile polycrystalline structure are described. The main types of polycrystalline structures are detailed. It has been proposed and founded the scenarios of formation of bile microscopic images polarization structure in coherent radiation. The results of investigating the interrelation between statistical moments of the 1st-4th order are presented that characterize the coordinate distributions of intensity of laser images of bile smears of cholelithiasis patients in combination with other pathologies. The diagnostic criteria of the cholelithiasis nascency and its severity degree differentiation are determined.
Kinetics of first-order phase transitions with correlated nuclei
NASA Astrophysics Data System (ADS)
Rickman, J. M.; Barmak, K.
2017-02-01
We demonstrate that the time evolution of a first-order phase transition may be described quite generally in terms of the statistics of point processes, thereby providing an intuitive framework for visualizing transition kinetics. A number of attractive and repulsive nucleation scenarios is examined followed by isotropic domain growth at a constant rate This description holds for both uncorrelated and correlated nuclei, and may be employed to calculate the nonequilibrium, n -point spatiotemporal correlations that characterize the transition. Furthermore, it is shown that the interpretation of the one-point function in terms of a stretched-exponential, Kolmogorov-Johnson-Mehl-Avrami result is problematic in the case of correlated nuclei, but that the calculation of higher-order correlation functions permits one to distinguish among various nucleation scenarios.
Weak value amplification via second-order correlated technique
NASA Astrophysics Data System (ADS)
Ting, Cui; Jing-Zheng, Huang; Xiang, Liu; Gui-Hua, Zeng
2016-02-01
We propose a new framework combining weak measurement and second-order correlated technique. The theoretical analysis shows that weak value amplification (WVA) experiment can also be implemented by a second-order correlated system. We then build two-dimensional second-order correlated function patterns for achieving higher amplification factor and discuss the signal-to-noise ratio influence. Several advantages can be obtained by our proposal. For instance, detectors with high resolution are not necessary. Moreover, detectors with low saturation intensity are available in WVA setup. Finally, type-one technical noise can be effectively suppressed. Project supported by the Union Research Centre of Advanced Spaceflight Technology (Grant No. USCAST2013-05), the National Natural Science Foundation of China (Grant Nos. 61170228, 61332019, and 61471239), and the High-Tech Research and Development Program of China (Grant No. 2013AA122901).
Machine learning using a higher order correlation network
Lee, Y.C.; Doolen, G.; Chen, H.H.; Sun, G.Z.; Maxwell, T.; Lee, H.Y.
1986-01-01
A high-order correlation tensor formalism for neural networks is described. The model can simulate auto associative, heteroassociative, as well as multiassociative memory. For the autoassociative model, simulation results show a drastic increase in the memory capacity and speed over that of the standard Hopfield-like correlation matrix methods. The possibility of using multiassociative memory for a learning universal inference network is also discussed. 9 refs., 5 figs.
Modeling Higher-Order Correlations within Cortical Microcolumns
Köster, Urs; Sohl-Dickstein, Jascha; Gray, Charles M.; Olshausen, Bruno A.
2014-01-01
We statistically characterize the population spiking activity obtained from simultaneous recordings of neurons across all layers of a cortical microcolumn. Three types of models are compared: an Ising model which captures pairwise correlations between units, a Restricted Boltzmann Machine (RBM) which allows for modeling of higher-order correlations, and a semi-Restricted Boltzmann Machine which is a combination of Ising and RBM models. Model parameters were estimated in a fast and efficient manner using minimum probability flow, and log likelihoods were compared using annealed importance sampling. The higher-order models reveal localized activity patterns which reflect the laminar organization of neurons within a cortical column. The higher-order models also outperformed the Ising model in log-likelihood: On populations of 20 cells, the RBM had 10% higher log-likelihood (relative to an independent model) than a pairwise model, increasing to 45% gain in a larger network with 100 spatiotemporal elements, consisting of 10 neurons over 10 time steps. We further removed the need to model stimulus-induced correlations by incorporating a peri-stimulus time histogram term, in which case the higher order models continued to perform best. These results demonstrate the importance of higher-order interactions to describe the structure of correlated activity in cortical networks. Boltzmann Machines with hidden units provide a succinct and effective way to capture these dependencies without increasing the difficulty of model estimation and evaluation. PMID:24991969
Modeling higher-order correlations within cortical microcolumns.
Köster, Urs; Sohl-Dickstein, Jascha; Gray, Charles M; Olshausen, Bruno A
2014-07-01
We statistically characterize the population spiking activity obtained from simultaneous recordings of neurons across all layers of a cortical microcolumn. Three types of models are compared: an Ising model which captures pairwise correlations between units, a Restricted Boltzmann Machine (RBM) which allows for modeling of higher-order correlations, and a semi-Restricted Boltzmann Machine which is a combination of Ising and RBM models. Model parameters were estimated in a fast and efficient manner using minimum probability flow, and log likelihoods were compared using annealed importance sampling. The higher-order models reveal localized activity patterns which reflect the laminar organization of neurons within a cortical column. The higher-order models also outperformed the Ising model in log-likelihood: On populations of 20 cells, the RBM had 10% higher log-likelihood (relative to an independent model) than a pairwise model, increasing to 45% gain in a larger network with 100 spatiotemporal elements, consisting of 10 neurons over 10 time steps. We further removed the need to model stimulus-induced correlations by incorporating a peri-stimulus time histogram term, in which case the higher order models continued to perform best. These results demonstrate the importance of higher-order interactions to describe the structure of correlated activity in cortical networks. Boltzmann Machines with hidden units provide a succinct and effective way to capture these dependencies without increasing the difficulty of model estimation and evaluation.
Biological network inference using low order partial correlation.
Zuo, Yiming; Yu, Guoqiang; Tadesse, Mahlet G; Ressom, Habtom W
2014-10-01
Biological network inference is a major challenge in systems biology. Traditional correlation-based network analysis results in too many spurious edges since correlation cannot distinguish between direct and indirect associations. To address this issue, Gaussian graphical models (GGM) were proposed and have been widely used. Though they can significantly reduce the number of spurious edges, GGM are insufficient to uncover a network structure faithfully due to the fact that they only consider the full order partial correlation. Moreover, when the number of samples is smaller than the number of variables, further technique based on sparse regularization needs to be incorporated into GGM to solve the singular covariance inversion problem. In this paper, we propose an efficient and mathematically solid algorithm that infers biological networks by computing low order partial correlation (LOPC) up to the second order. The bias introduced by the low order constraint is minimal compared to the more reliable approximation of the network structure achieved. In addition, the algorithm is suitable for a dataset with small sample size but large number of variables. Simulation results show that LOPC yields far less spurious edges and works well under various conditions commonly seen in practice. The application to a real metabolomics dataset further validates the performance of LOPC and suggests its potential power in detecting novel biomarkers for complex disease.
Charge Ordered Insulator without Magnetic Order Studied by Correlator Projection Method
NASA Astrophysics Data System (ADS)
Hanasaki, Kota; Imada, Masatoshi
2005-10-01
The Hubbard model with additional intersite interaction ‘V’ (the extended Hubbard model) is investigated by the correlator projection method (CPM). CPM is a newly developed numerical method that combines the equation-of-motion approach and the dynamical mean-field theory. Using this method, properties of the extended Hubbard Model at quarter filling are discussed with special emphasis on the metal-insulator transition induced by electron-electron correlations. As we increase the interaction, a metal-insulator transition to a charge ordered insulator with antiferromagnetic order occurs at low temperatures, but a metal-insulator transition to a charge ordered insulator without magnetic symmetry breaking occurs at intermediate temperatures. Here, the magnetic order is found to be confined to low temperatures because of the smallness of the exchange coupling Jeff. The present results are in sharp contrast to the Hatree--Fock approximation whereas they are in agreement with the experimental results on quarter-filled materials with strong correlations such as organic BEDT-TTF conductors.
Frustration and chiral orderings in correlated electron systems
NASA Astrophysics Data System (ADS)
Batista, Cristian D.; Lin, Shi-Zeng; Hayami, Satoru; Kamiya, Yoshitomo
2016-08-01
The term frustration refers to lattice systems whose ground state cannot simultaneously satisfy all the interactions. Frustration is an important property of correlated electron systems, which stems from the sign of loop products (similar to Wilson products) of interactions on a lattice. It was early recognized that geometric frustration can produce rather exotic physical behaviors, such as macroscopic ground state degeneracy and helimagnetism. The interest in frustrated systems was renewed two decades later in the context of spin glasses and the emergence of magnetic superstructures. In particular, Phil Anderson’s proposal of a quantum spin liquid ground state for a two-dimensional lattice S = 1/2 Heisenberg magnet generated a very active line of research that still continues. As a result of these early discoveries and conjectures, the study of frustrated models and materials exploded over the last two decades. Besides the large efforts triggered by the search of quantum spin liquids, it was also recognized that frustration plays a crucial role in a vast spectrum of physical phenomena arising from correlated electron materials. Here we review some of these phenomena with particular emphasis on the stabilization of chiral liquids and non-coplanar magnetic orderings. In particular, we focus on the ubiquitous interplay between magnetic and charge degrees of freedom in frustrated correlated electron systems and on the role of anisotropy. We demonstrate that these basic ingredients lead to exotic phenomena, such as, charge effects in Mott insulators, the stabilization of single magnetic vortices, as well as vortex and skyrmion crystals, and the emergence of different types of chiral liquids. In particular, these orderings appear more naturally in itinerant magnets with the potential of inducing a very large anomalous Hall effect.
Order and correlation contributions to the entropy of hydrophobic solvation
NASA Astrophysics Data System (ADS)
Liu, Maoyuan; Besford, Quinn Alexander; Mulvaney, Thomas; Gray-Weale, Angus
2015-03-01
The entropy of hydrophobic solvation has been explained as the result of ordered solvation structures, of hydrogen bonds, of the small size of the water molecule, of dispersion forces, and of solvent density fluctuations. We report a new approach to the calculation of the entropy of hydrophobic solvation, along with tests of and comparisons to several other methods. The methods are assessed in the light of the available thermodynamic and spectroscopic information on the effects of temperature on hydrophobic solvation. Five model hydrophobes in SPC/E water give benchmark solvation entropies via Widom's test-particle insertion method, and other methods and models are tested against these particle-insertion results. Entropies associated with distributions of tetrahedral order, of electric field, and of solvent dipole orientations are examined. We find these contributions are small compared to the benchmark particle-insertion entropy. Competitive with or better than other theories in accuracy, but with no free parameters, is the new estimate of the entropy contributed by correlations between dipole moments. Dipole correlations account for most of the hydrophobic solvation entropy for all models studied and capture the distinctive temperature dependence seen in thermodynamic and spectroscopic experiments. Entropies based on pair and many-body correlations in number density approach the correct magnitudes but fail to describe temperature and size dependences, respectively. Hydrogen-bond definitions and free energies that best reproduce entropies from simulations are reported, but it is difficult to choose one hydrogen bond model that fits a variety of experiments. The use of information theory, scaled-particle theory, and related methods is discussed briefly. Our results provide a test of the Frank-Evans hypothesis that the negative solvation entropy is due to structured water near the solute, complement the spectroscopic detection of that solvation structure by
Order and correlation contributions to the entropy of hydrophobic solvation
Liu, Maoyuan; Besford, Quinn Alexander; Mulvaney, Thomas; Gray-Weale, Angus
2015-03-21
The entropy of hydrophobic solvation has been explained as the result of ordered solvation structures, of hydrogen bonds, of the small size of the water molecule, of dispersion forces, and of solvent density fluctuations. We report a new approach to the calculation of the entropy of hydrophobic solvation, along with tests of and comparisons to several other methods. The methods are assessed in the light of the available thermodynamic and spectroscopic information on the effects of temperature on hydrophobic solvation. Five model hydrophobes in SPC/E water give benchmark solvation entropies via Widom’s test-particle insertion method, and other methods and models are tested against these particle-insertion results. Entropies associated with distributions of tetrahedral order, of electric field, and of solvent dipole orientations are examined. We find these contributions are small compared to the benchmark particle-insertion entropy. Competitive with or better than other theories in accuracy, but with no free parameters, is the new estimate of the entropy contributed by correlations between dipole moments. Dipole correlations account for most of the hydrophobic solvation entropy for all models studied and capture the distinctive temperature dependence seen in thermodynamic and spectroscopic experiments. Entropies based on pair and many-body correlations in number density approach the correct magnitudes but fail to describe temperature and size dependences, respectively. Hydrogen-bond definitions and free energies that best reproduce entropies from simulations are reported, but it is difficult to choose one hydrogen bond model that fits a variety of experiments. The use of information theory, scaled-particle theory, and related methods is discussed briefly. Our results provide a test of the Frank-Evans hypothesis that the negative solvation entropy is due to structured water near the solute, complement the spectroscopic detection of that solvation structure by
Testing quantum mechanics using third-order correlations
NASA Astrophysics Data System (ADS)
Kinsler, Paul
1996-04-01
Semiclassical theories similar to stochastic electrodynamics are widely used in optics. The distinguishing feature of such theories is that the quantum uncertainty is represented by random statistical fluctuations. They can successfully predict some quantum-mechanical phenomena; for example, the squeezing of the quantum uncertainty in the parametric oscillator. However, since such theories are not equivalent to quantum mechanics, they will not always be useful. Complex number representations can be used to exactly model the quantum uncertainty, but care has to be taken that approximations do not reduce the description to a hidden variable one. This paper helps show the limitations of ``semiclassical theories,'' and helps show where a true quantum-mechanical treatment needs to be used. Third-order correlations are a test that provides a clear distinction between quantum and hidden variable theories in a way analogous to that provided by the ``all or nothing'' Greenberger-Horne-Zeilinger test of local hidden variable theories.
Second-order spatial correlation in the far-field: Comparing entangled and classical light sources
NASA Astrophysics Data System (ADS)
Zhang, Erfeng; Liu, Weitao; Lin, Huizu; Chen, Pingxing
2016-02-01
We consider second-order spatial correlation with entangled and classical light in the far-field. The quantum theory of second-order spatial correlation is analyzed, and the role of photon statistics and detection mode in the second-order spatial correlation are discussed. Meanwhile, the difference of second-order spatial correlation with entangled and classical light sources is deduced.
Bond Order Correlations in the 2D Hubbard Model
NASA Astrophysics Data System (ADS)
Moore, Conrad; Abu Asal, Sameer; Yang, Shuxiang; Moreno, Juana; Jarrell, Mark
We use the dynamical cluster approximation to study the bond correlations in the Hubbard model with next nearest neighbor (nnn) hopping to explore the region of the phase diagram where the Fermi liquid phase is separated from the pseudogap phase by the Lifshitz line at zero temperature. We implement the Hirsch-Fye cluster solver that has the advantage of providing direct access to the computation of the bond operators via the decoupling field. In the pseudogap phase, the parallel bond order susceptibility is shown to persist at zero temperature while it vanishes for the Fermi liquid phase which allows the shape of the Lifshitz line to be mapped as a function of filling and nnn hopping. Our cluster solver implements NVIDIA's CUDA language to accelerate the linear algebra of the Quantum Monte Carlo to help alleviate the sign problem by allowing for more Monte Carlo updates to be performed in a reasonable amount of computation time. Work supported by the NSF EPSCoR Cooperative Agreement No. EPS-1003897 with additional support from the Louisiana Board of Regents.
Strong correlations and topological order in one-dimensional systems
NASA Astrophysics Data System (ADS)
De Gottardi, Wade Wells
This thesis presents theoretical studies of strongly correlated systems as well as topologically ordered systems in 1D. Non-Fermi liquid behavior characteristic of interacting 1D electron systems is investigated with an emphasis on experimentally relevant setups and observables. The existence of end Majorana fermions in a 1D p-wave superconductor subject to periodic, incommensurate and disordered potentials is studied. The Tomonaga-Luttinger liquid (TLL), a model of interacting electrons in one spatial dimension, is considered in the context of two systems of experimental interest. First, a study of the electronic properties of single-walled armchair carbon nanotubes in the presence of transverse electric and magnetic fields is presented. As a result of their effect on the band structure and electron wave functions, fields alter the nature of the (effective) Coulomb interaction in tubes. In particular, it is found that fields couple to nanotube bands (or valleys), a quantum degree of freedom inherited from the underlying graphene lattice. As revealed by a detailed TLL calculation, it is predicted that fields induce electrons to disperse into their spin, band, and charge components. Fields also provide a means of tuning the shell-filling behavior associated with short tubes. The phenomenon of charge fractionalization is investigated in a one-dimensional ring. TLL theory predicts that momentum-resolved electrons injected into the ring will fractionalize into clockwise- and counterclockwise-moving quasiparticles. As a complement to transport measurements in quantum wires connected to leads, non-invasive measures involving the magnetic field profiles around the ring are proposed. Topological aspects of 1D p-wave superconductors are explored. The intimate connection between non-trivial topology (fermions) and spontaneous symmetry breaking (spins) in one-dimension is investigated. Building on this connection, a spin ladder system endowed with vortex degrees of freedom is
Optimal gene partition into operons correlates with gene functional order
NASA Astrophysics Data System (ADS)
Zaslaver, Alon; Mayo, Avi; Ronen, Michal; Alon, Uri
2006-09-01
Gene arrangement into operons varies between bacterial species. Genes in a given system can be on one operon in some organisms and on several operons in other organisms. Existing theories explain why genes that work together should be on the same operon, since this allows for advantageous lateral gene transfer and accurate stoichiometry. But what causes the frequent separation into multiple operons of co-regulated genes that act together in a pathway? Here we suggest that separation is due to benefits made possible by differential regulation of each operon. We present a simple mathematical model for the optimal distribution of genes into operons based on a balance of the cost of operons and the benefit of regulation that provides 'just-when-needed' temporal order. The analysis predicts that genes are arranged such that genes on the same operon do not skip functional steps in the pathway. This prediction is supported by genomic data from 137 bacterial genomes. Our work suggests that gene arrangement is not only the result of random historical drift, genome re-arrangement and gene transfer, but has elements that are solutions of an evolutionary optimization problem. Thus gene functional order may be inferred by analyzing the operon structure across different genomes.
Correlates of viral richness in bats (order Chiroptera).
Turmelle, Amy S; Olival, Kevin J
2009-12-01
Historic and contemporary host ecology and evolutionary dynamics have profound impacts on viral diversity, virulence, and associated disease emergence. Bats have been recognized as reservoirs for several emerging viral pathogens, and are unique among mammals in their vagility, potential for long-distance dispersal, and often very large, colonial populations. We investigate the relative influences of host ecology and population genetic structure for predictions of viral richness in relevant reservoir species. We test the hypothesis that host geographic range area, distribution, population genetic structure, migratory behavior, International Union for Conservation of Nature and Natural Resources (IUCN) threat status, body mass, and colony size, are associated with known viral richness in bats. We analyze host traits and viral richness in a generalized linear regression model framework, and include a correction for sampling effort and phylogeny. We find evidence that sampling effort, IUCN status, and population genetic structure correlate with observed viral species richness in bats, and that these associations are independent of phylogeny. This study is an important first step in understanding the mechanisms that promote viral richness in reservoir species, and may aid in predicting the emergence of viral zoonoses from bats.
Role of intensity fluctuations in third-order correlation double-slit interference of thermal light.
Chen, Xi-Hao; Chen, Wen; Meng, Shao-Ying; Wu, Wei; Wu, Ling-An; Zhai, Guang-Jie
2013-07-01
A third-order double-slit interference experiment with a pseudothermal light source in the high-intensity limit has been performed by actually recording the intensities in three optical paths. It is shown that not only can the visibility be dramatically enhanced compared to the second-order case as previously theoretically predicted and shown experimentally, but also that the higher visibility is a consequence of the contribution of third-order correlation interaction terms, which is equal to the sum of all contributions from second-order correlation. It is interesting that, when the two reference detectors are scanned in opposite directions, negative values for the third-order correlation term of the intensity fluctuations may appear. The phenomenon can be completely explained by the theory of classical statistical optics and is the first concrete demonstration of the influence of the third-order correlation terms.
Pulse transmission receiver with higher-order time derivative pulse correlator
Dress, Jr., William B.; Smith, Stephen F.
2003-09-16
Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission receiver includes: a higher-order time derivative pulse correlator; a demodulation decoder coupled to the higher-order time derivative pulse correlator; a clock coupled to the demodulation decoder; and a pseudorandom polynomial generator coupled to both the higher-order time derivative pulse correlator and the clock. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.
An Analytical Model for the Three-Point Third-Order Velocity Correlation in Isotropic Turbulence
NASA Astrophysics Data System (ADS)
Chang, Henry; Moser, Robert
2006-11-01
In turbulent flows, the three-point third-order velocity correlation Tijk(r,r') =
CuBIC: cumulant based inference of higher-order correlations in massively parallel spike trains
Rotter, Stefan; Grün, Sonja
2009-01-01
Recent developments in electrophysiological and optical recording techniques enable the simultaneous observation of large numbers of neurons. A meaningful interpretation of the resulting multivariate data, however, presents a serious challenge. In particular, the estimation of higher-order correlations that characterize the cooperative dynamics of groups of neurons is impeded by the combinatorial explosion of the parameter space. The resulting requirements with respect to sample size and recording time has rendered the detection of coordinated neuronal groups exceedingly difficult. Here we describe a novel approach to infer higher-order correlations in massively parallel spike trains that is less susceptible to these problems. Based on the superimposed activity of all recorded neurons, the cumulant-based inference of higher-order correlations (CuBIC) presented here exploits the fact that the absence of higher-order correlations imposes also strong constraints on correlations of lower order. Thus, estimates of only few lower-order cumulants suffice to infer higher-order correlations in the population. As a consequence, CuBIC is much better compatible with the constraints of in vivo recordings than previous approaches, which is shown by a systematic analysis of its parameter dependence. PMID:19862611
On the accuracy of second-order Møller-Plesset correlation energies
NASA Astrophysics Data System (ADS)
Flores, J. R.
1997-05-01
Accurate second-order Møller-Plesset correlation energies are computed and compared with several semi-empirical estimates of the total correlation energies including those provided by Clementi, Anno and Teruya, and the recent results of Davidson, Froese and co-workers, for atoms with ten, twelve and eighteen electrons. Somewhat surprisingly, the MP2 correlation energies present what is considered to be in good agreement with the newest estimates, especially when the behaviour with the nuclear charge is examined.
ERIC Educational Resources Information Center
Sen, Anindya; Clemente, Anthony
2010-01-01
We exploit the 1986, 1994, and 2001 waves of the Canadian general social surveys in order to estimate intergenerational correlations in education. The use of these specific data is important because of available information on the final educational attainment of survey respondents and both parents, as well as family size and birth order. OLS…
Sadhukhan, Debasis; Prabhu, R; Sen De, Aditi; Sen, Ujjwal
2016-03-01
We investigate the behavior of quantum correlations of paradigmatic quenched disordered quantum spin models, viz., the XY spin glass and random-field XY models. We show that quenched averaged quantum correlations can exhibit the order-from-disorder phenomenon for finite-size systems as well as in the thermodynamic limit. Moreover, we find that the order-from-disorder can become more pronounced in the presence of temperature by suitable tuning of the system parameters. The effects are found for entanglement measures as well as for information-theoretic quantum correlation ones, although the former show them more prominently. We also observe that the equivalence between the quenched averages and their self-averaged cousins--for classical and quantum correlations--is related to the quantum critical point in the corresponding ordered system.
Correlation of coming limit price with order book in stock markets
NASA Astrophysics Data System (ADS)
Maskawa, Jun-ichi
2007-09-01
We examine the correlation of the limit price with the order book, when a limit order comes. We analyzed the Rebuild Order Book of Stock Exchange Electronic Trading Service, which is the centralized order book market of London Stock Exchange. As a result, the limit price is broadly distributed around the best price according to a power-law, and it is not randomly drawn from the distribution, but has a strong correlation with the size of cumulative unexecuted limit orders on the price. It was also found that the limit price, on the coarse-grained price scale, tends to gather around the price which has a large size of cumulative unexecuted limit orders.
Non-local bias contribution to third-order galaxy correlations
NASA Astrophysics Data System (ADS)
Bel, J.; Hoffmann, K.; Gaztañaga, E.
2015-10-01
We study halo clustering bias with second- and third-order statistics of halo and matter density fields in the Marenostrum Institut de Ciències de l'Espai (MICE) Grand Challenge simulation. We verify that two-point correlations deliver reliable estimates of the linear bias parameters at large scales, while estimations from the variance can be significantly affected by non-linear and possibly non-local contributions to the bias function. Combining three-point auto- and cross-correlations we find, for the first time in configuration space, evidence for the presence of such non-local contributions. These contributions are consistent with predicted second-order non-local effects on the bias functions originating from the dark matter tidal field. Samples of massive haloes show indications of bias (local or non-local) beyond second order. Ignoring non-local bias causes 20-30 and 5-10 per cent overestimation of the linear bias from three-point auto- and cross-correlations, respectively. We study two third-order bias estimators that are not affected by second-order non-local contributions. One is a combination of three-point auto- and cross-correlations. The other is a combination of third-order one- and two-point cumulants. Both methods deliver accurate estimations of the linear bias. Ignoring non-local bias causes higher values of the second-order bias from three-point correlations. Our results demonstrate that third-order statistics can be employed for breaking the growth-bias degeneracy.
Out-of-time-ordered correlators and purity in rational conformal field theories
NASA Astrophysics Data System (ADS)
Caputa, Paweł; Numasawa, Tokiro; Veliz-Osorio, Alvaro
2016-11-01
In this paper we investigate measures of chaos and entanglement in rational conformal field theories in 1 + 1 dimensions. First, we derive a formula for the late time value of the out-of-time-ordered correlators for this class of theories. Our universal result can be expressed as a particular combination of the modular S-matrix elements known as anyon monodromy scalar. Next, in the explicit setup of an SUN Wess-Zumino-Witten model, we compare the late time behavior of the out-of-time-ordered correlators and the purity. Interestingly, in the large-c limit, the purity grows logarithmically as in holographic theories; in contrast, the out-of-time-ordered correlators remain, in general, nonvanishing.
Magnetic Reversal of an Artificial Square Ice: Dipolar Correlation and Charge Ordering
Stein A.; Morgan J.P.; Langridge S.; Marrows C.H.
2011-10-13
Magnetic reversal of an artificial square ice pattern subject to a sequence of magnetic fields applied slightly off the diagonal axis is investigated via magnetic force microscopy of the remanent states that result. Sublattice independent reversal is observed via correlated incrementally pinned flip cascades along parallel dipolar chains, as evident from analysis of vertex populations and dipolar correlation functions. Weak dipolar interactions between adjacent chains favour antialignment and give rise to weak charge ordering of 'monopole' vertices during the reversal process.
Neipert, Christine; Space, Brian
2006-12-14
Sum vibrational frequency spectroscopy, a second order optical process, is interface specific in the dipole approximation. At charged interfaces, there exists a static field, and as a direct consequence, the experimentally detected signal is a combination of enhanced second and static field induced third order contributions. There is significant evidence in the literature of the importance/relative magnitude of this third order contribution, but no previous molecularly detailed approach existed to separately calculate the second and third order contributions. Thus, for the first time, a molecularly detailed time correlation function theory is derived here that allows for the second and third order contributions to sum frequency vibrational spectra to be individually determined. Further, a practical, molecular dynamics based, implementation procedure for the derived correlation functions that describe the third order phenomenon is also presented. This approach includes a novel generalization of point atomic polarizability models to calculate the hyperpolarizability of a molecular system. The full system hyperpolarizability appears in the time correlation functions responsible for third order contributions in the presence of a static field.
Electron spin polarization by isospin ordering in correlated two-layer quantum Hall systems.
Tiemann, L; Wegscheider, W; Hauser, M
2015-05-01
Enhancement of the electron spin polarization in a correlated two-layer, two-dimensional electron system at a total Landau level filling factor of 1 is reported. Using resistively detected nuclear magnetic resonance, we demonstrate that the electron spin polarization of two closely spaced two-dimensional electron systems becomes maximized when interlayer Coulomb correlations establish spontaneous isospin ferromagnetic order. This correlation-driven polarization dominates over the spin polarizations of competing single-layer fractional quantum Hall states under electron density imbalances.
The costs of ignoring high-order correlations in populations of model neurons.
Michel, Melchi M; Jacobs, Robert A
2006-03-01
Investigators debate the extent to which neural populations use pair-wise and higher-order statistical dependencies among neural responses to represent information about a visual stimulus. To study this issue, three statistical decoders were used to extract the information in the responses of model neurons about the binocular disparities present in simulated pairs of left-eye and right-eye images: (1) the full joint probability decoder considered all possible statistical relations among neural responses as potentially important; (2) the dependence tree decoder also considered all possible relations as potentially important, but it approximated high-order statistical correlations using a computationally tractable procedure; and (3) the independent response decoder, which assumed that neural responses are statistically independent, meaning that all correlations should be zero and thus can be ignored. Simulation results indicate that high-order correlations among model neuron responses contain significant information about binocular disparities and that the amount of this high-order information increases rapidly as a function of neural population size. Furthermore, the results highlight the potential importance of the dependence tree decoder to neuroscientists as a powerful but still practical way of approximating high-order correlations among neural responses.
Measuring the growth of matter fluctuations with third-order galaxy correlations
NASA Astrophysics Data System (ADS)
Hoffmann, K.; Bel, J.; Gaztañaga, E.; Crocce, M.; Fosalba, P.; Castander, F. J.
2015-02-01
Measurements of the linear growth factor D at different redshifts z are key to distinguish among cosmological models. One can estimate the derivative dD(z)/dln (1 + z) from redshift space measurements of the 3D anisotropic galaxy two-point correlation ξ(z), but the degeneracy of its transverse (or projected) component with galaxy bias b, i.e. ξ⊥(z) ∝ D2(z)b2(z), introduces large errors in the growth measurement. Here, we present a comparison between two methods which breaks this degeneracy by combining second- and third-order statistics. One uses the shape of the reduced three-point correlation and the other a combination of third-order one- and two-point cumulants. These methods use the fact that, for Gaussian initial conditions and scales larger than 20 h-1 Mpc, the reduced third-order matter correlations are independent of redshift (and therefore of the growth factor), while the third-order galaxy correlations depend on b. We use matter and halo catalogues from the MICE-GC simulation to test how well we can recover b(z) and therefore D(z) with these methods in 3D real space. We also present a new approach, which enables us to measure D directly from the redshift evolution of the second- and third-order galaxy correlations without the need of modelling matter correlations. For haloes with masses lower than 1014 h-1 M⊙, we find 10 per cent deviations between the different estimates of D, which are comparable to current observational errors. At higher masses, we find larger differences that can probably be attributed to the breakdown of the bias model and non-Poissonian shot noise.
Statistical modelling of higher-order correlations in pools of neural activity
NASA Astrophysics Data System (ADS)
Montani, Fernando; Phoka, Elena; Portesi, Mariela; Schultz, Simon R.
2013-07-01
Simultaneous recordings from multiple neural units allow us to investigate the activity of very large neural ensembles. To understand how large ensembles of neurons process sensory information, it is necessary to develop suitable statistical models to describe the response variability of the recorded spike trains. Using the information geometry framework, it is possible to estimate higher-order correlations by assigning one interaction parameter to each degree of correlation, leading to a (2N-1)-dimensional model for a population with N neurons. However, this model suffers greatly from a combinatorial explosion, and the number of parameters to be estimated from the available sample size constitutes the main intractability reason of this approach. To quantify the extent of higher than pairwise spike correlations in pools of multiunit activity, we use an information-geometric approach within the framework of the extended central limit theorem considering all possible contributions from higher-order spike correlations. The identification of a deformation parameter allows us to provide a statistical characterisation of the amount of higher-order correlations in the case of a very large neural ensemble, significantly reducing the number of parameters, avoiding the sampling problem, and inferring the underlying dynamical properties of the network within pools of multiunit neural activity.
Polyakov loop and correlator of Polyakov loops at next-to-next-to-leading order
Brambilla, Nora; Vairo, Antonio; Ghiglieri, Jacopo; Petreczky, Peter
2010-10-01
We study the Polyakov loop and the correlator of two Polyakov loops at finite temperature in the weak-coupling regime. We calculate the Polyakov loop at order g{sup 4}. The calculation of the correlator of two Polyakov loops is performed at distances shorter than the inverse of the temperature and for electric screening masses larger than the Coulomb potential. In this regime, it is accurate up to order g{sup 6}. We also evaluate the Polyakov-loop correlator in an effective field theory framework that takes advantage of the hierarchy of energy scales in the problem and makes explicit the bound-state dynamics. In the effective field theory framework, we show that the Polyakov-loop correlator is at leading order in the multipole expansion the sum of a color-singlet and a color-octet quark-antiquark correlator, which are gauge invariant, and compute the corresponding color-singlet and color-octet free energies.
Higher-order correlations in common input shapes the output spiking activity of a neural population
NASA Astrophysics Data System (ADS)
Montangie, Lisandro; Montani, Fernando
2017-04-01
Recent neurophysiological experiments suggest that populations of neurons use a computational scheme in which spike timing is regulated by common non-Gaussian inputs across neurons. The presence of beyond-pairwise correlations in the neuronal inputs and the spiking outputs following a non-Gaussian statistics elicits the need of developing a new theoretical framework taking into account the complexity of synchronous activity patterns. To this end, we quantify the amount of higher-order correlations in the common neuronal inputs and outputs of a population of neurons. We provide a novel formalism, of easy numerical implementation, that can capture the subtle changes of the inputs heterogeneities. Within our approach, correlations across neurons arise from q-Gaussian inputs into threshold neurons and higher-order correlations in the spiking outputs activity are quantified by the parameter q. We present an exhaustive analysis of how input statistics are transformed in this threshold process into output statistics, and we show under which conditions higher-order correlations can lead to either bigger or smaller number of synchronized spikes in the neural population outputs.
ERIC Educational Resources Information Center
Facao, M.; Lopes, A.; Silva, A. L.; Silva, P.
2011-01-01
We propose an undergraduate numerical project for simulating the results of the second-order correlation function as obtained by an intensity interference experiment for two kinds of light, namely bunched light with Gaussian or Lorentzian power density spectrum and antibunched light obtained from single-photon sources. While the algorithm for…
Extension of local-type inequality for the higher order correlation functions
Suyama, Teruaki; Yokoyama, Shuichiro E-mail: shu@a.phys.nagoya-u.ac.jp
2011-07-01
For the local-type primordial perturbation, it is known that there is an inequality between the bispectrum and the trispectrum. By using the diagrammatic method, we develop a general formalism to systematically construct the similar inequalities up to any order correlation function. As an application, we explicitly derive all the inequalities up to six and eight-point functions.
Tew, David P; Helmich, Benjamin; Hättig, Christof
2011-08-21
We explore using a pair natural orbital analysis of approximate first-order pair functions as means to truncate the space of both virtual and complementary auxiliary orbitals in the context of explicitly correlated F12 methods using localised occupied orbitals. We demonstrate that this offers an attractive procedure and that only 10-40 virtual orbitals per significant pair are required to obtain second-order valence correlation energies to within 1-2% of the basis set limit. Moreover, for this level of virtual truncation, only 10-40 complementary auxiliary orbitals per pair are required for an accurate resolution of the identity in the computation of the three- and four-electron integrals that arise in explicitly correlated methods.
NASA Astrophysics Data System (ADS)
Ikuta, Akira; Orimoto, Hisako; Ogawa, Hitoshi
In this study, a stochastic detection method of failure of machines based on the changing information of not only a linear correlation but also the higher order nonlinear correlation is proposed in a form suitable for on-line signal processing in time domain by using a personal computer, especially in order to find minutely the mutual relationship between sound and vibration emitted from rotational machines. More specifically, a conditional probability hierarchically reflecting various types of correlation information is theoretically derived by introducing an expression on the multi-dimensional probability distribution in orthogonal expansion series form. The effectiveness of the proposed theory is experimentally confirmed by applying it to the observed data emitted from a rotational machine driven by an electric motor.
Characterizing many-body localization by out-of-time-ordered correlation
NASA Astrophysics Data System (ADS)
He, Rong-Qiang; Lu, Zhong-Yi
2017-02-01
The out-of-time-ordered (OTO) correlation is a key quantity for quantifying quantum chaoticity and has been recently used in the investigation of quantum holography. Here we use it to study and characterize many-body localization (MBL). We find that a long-time logarithmic variation of the OTO correlation occurs in the MBL phase but is absent in the Anderson localized and ergodic phases. We extract a localization length in the MBL phase, which depends logarithmically on interaction and diverges at a critical interaction. Furthermore, the infinite-time "thermal" fluctuation of the OTO correlation is zero (finite) in the ergodic (MBL) phase and thus can be considered as an order parameter for the ergodic-MBL transition, through which the transition can be identified and characterized. Specifically, the critical point and the related critical exponents can be calculated.
Size correlated long and short range order of ternary Co2FeGa Heusler nanoparticles
NASA Astrophysics Data System (ADS)
Wang, C. H.; Guo, Y. Z.; Casper, F.; Balke, B.; Fecher, G. H.; Felser, C.; Hwu, Y.
2010-09-01
The long and short range order of chemically prepared Co2FeGa Heusler nanoparticles with various sizes are determined by x-ray diffraction (XRD) and extended x-ray absorption fine structure (EXAFS) spectroscopy. Specifically, EXAFS fittings reveal the size dependent crystal structure and short range order of the Heusler type Co2FeGa nanoparticles. With decreasing particle size, the degree of L21 order in the nanoparticles decreases and the probability of B2 disorder increases simultaneously. The consequences of antisite disorder on the size correlated structure of Co2FeGa nanoparticles are also discussed.
Multi-omics approach for estimating metabolic networks using low-order partial correlations.
Kayano, Mitsunori; Imoto, Seiya; Yamaguchi, Rui; Miyano, Satoru
2013-08-01
Two typical purposes of metabolome analysis are to estimate metabolic pathways and to understand the regulatory systems underlying the metabolism. A powerful source of information for these analyses is a set of multi-omics data for RNA, proteins, and metabolites. However, integrated methods that analyze multi-omics data simultaneously and unravel the systems behind metabolisms have not been well established. We developed a statistical method based on low-order partial correlations with a robust correlation coefficient for estimating metabolic networks from metabolome, proteome, and transcriptome data. Our method is defined by the maximum of low-order, particularly first-order, partial correlations (MF-PCor) in order to assign a correct edge with the highest correlation and to detect the factors that strongly affect the correlation coefficient. First, through numerical experiments with real and synthetic data, we showed that the use of protein and transcript data of enzymes improved the accuracy of the estimated metabolic networks in MF-PCor. In these experiments, the effectiveness of the proposed method was also demonstrated by comparison with a correlation network (Cor) and a Gaussian graphical model (GGM). Our theoretical investigation confirmed that the performance of MF-PCor could be superior to that of the competing methods. In addition, in the real data analysis, we investigated the role of metabolites, enzymes, and enzyme genes that were identified as important factors in the network established by MF-PCor. We then found that some of them corresponded to specific reactions between metabolites mediated by catalytic enzymes that were difficult to be identified by analysis based on metabolite data alone.
Multilabel image classification via high-order label correlation driven active learning.
Zhang, Bang; Wang, Yang; Chen, Fang
2014-03-01
Supervised machine learning techniques have been applied to multilabel image classification problems with tremendous success. Despite disparate learning mechanisms, their performances heavily rely on the quality of training images. However, the acquisition of training images requires significant efforts from human annotators. This hinders the applications of supervised learning techniques to large scale problems. In this paper, we propose a high-order label correlation driven active learning (HoAL) approach that allows the iterative learning algorithm itself to select the informative example-label pairs from which it learns so as to learn an accurate classifier with less annotation efforts. Four crucial issues are considered by the proposed HoAL: 1) unlike binary cases, the selection granularity for multilabel active learning need to be fined from example to example-label pair; 2) different labels are seldom independent, and label correlations provide critical information for efficient learning; 3) in addition to pair-wise label correlations, high-order label correlations are also informative for multilabel active learning; and 4) since the number of label combinations increases exponentially with respect to the number of labels, an efficient mining method is required to discover informative label correlations. The proposed approach is tested on public data sets, and the empirical results demonstrate its effectiveness.
Xu, Enhua; Zhao, Dongbo; Li, Shuhua
2015-10-13
A multireference second order perturbation theory based on a complete active space configuration interaction (CASCI) function or density matrix renormalized group (DMRG) function has been proposed. This method may be considered as an approximation to the CAS/A approach with the same reference, in which the dynamical correlation is simplified with blocked correlated second order perturbation theory based on the generalized valence bond (GVB) reference (GVB-BCPT2). This method, denoted as CASCI-BCPT2/GVB or DMRG-BCPT2/GVB, is size consistent and has a similar computational cost as the conventional second order perturbation theory (MP2). We have applied it to investigate a number of problems of chemical interest. These problems include bond-breaking potential energy surfaces in four molecules, the spectroscopic constants of six diatomic molecules, the reaction barrier for the automerization of cyclobutadiene, and the energy difference between the monocyclic and bicyclic forms of 2,6-pyridyne. Our test applications demonstrate that CASCI-BCPT2/GVB can provide comparable results with CASPT2 (second order perturbation theory based on the complete active space self-consistent-field wave function) for systems under study. Furthermore, the DMRG-BCPT2/GVB method is applicable to treat strongly correlated systems with large active spaces, which are beyond the capability of CASPT2.
NASA Astrophysics Data System (ADS)
Garcés, R.; Podgornik, R.; Lorman, V.
2015-06-01
Contrary to the usual "rigid supermolecular assembly" paradigm of chromatin structure, we propose to analyze its eventual ordered state in terms of symmetry properties of individual nucleosomes that give rise to mesophase order parameters, like in many other soft-matter systems. Basing our approach on the Landau-de Gennes phenomenology, we describe the mesoscale order in chromatin by antipolar and anticlinic correlations of chiral individual nucleosomes. This approach leads to a unifying physical picture of a whole series of soft locally ordered states with different apparent structures, including the recently observed heteromorphic chromatin, stemming from the antipolar arrangement of nucleosomes complemented by their chiral twisting. Properties of these states under an external force field can reconcile apparently contradictory results of single-molecule experiments.
Structural and psychosocial correlates of birth order anomalies in schizophrenia and homicide.
Schug, Robert A; Yang, Yaling; Raine, Adrian; Han, Chenbo; Liu, Jianghong
2010-12-01
Birth order--a unique index of both neurodevelopmental and/or psychosocial factors in the pathogenesis of psychiatric disorder--remains largely unexplored in violent schizophrenia. We examined whether murderers with schizophrenia would demonstrate birth order anomalies, distinguishing them from both nonviolent schizophrenia patients and murderers without schizophrenia. Self-report birth order, psychosocial history data (i.e., maternal birth age, family size, parental criminality, parental SES), and structural magnetic resonance imaging data were collected from normal controls, nonviolent schizophrenia patients, murderers with schizophrenia, murderers without schizophrenia, and murderers with psychiatric conditions other than schizophrenia at a brain hospital in Nanjing, China. Results indicated that murderers with schizophrenia were characterized by significantly increased (i.e., later) birth order compared with both nonviolent schizophrenia patients and murderers without schizophrenia. Additionally, birth order was negatively correlated with gray matter volume in key frontal subregions for schizophrenic murderers, and was negatively correlated with parental SES. Findings may suggest biological, psychosocial, or interactional trajectories which may lead to a homicidally violent outcome in schizophrenia.
NASA Astrophysics Data System (ADS)
Noda, Isao
2016-11-01
Modified forms of two-dimensional (2D) correlation spectra, i.e., sign-adjusted asynchronous spectrum and merged correlation spectrum, are discussed. They are developed for the streamlined determination of the sequential order of spectral intensity variations using only one 2D map by combining the pertinent information of synchronous and asynchronous spectra. Development of small side lobe artifacts near the peripheral of a cross peak is sometimes noted, especially for highly overlapped bands which are changing intensities in the opposite directions. The merit of the ease of interpretation afforded by the modification of correlation spectra probably outweighs the introduction minor artifacts, but some care certainly is required to avoid misinterpretation. Modified spectrum provides additional characteristic signature to the butterfly pattern cluster of cross peaks for the unambiguous identification of the presence of a band with position shift.
NASA Astrophysics Data System (ADS)
Buranasiri, Prathan
2005-04-01
Using barium titanate as the photorefractive material, we demonstrate phase conjugation, beam coupling, higher diffraction order generation. At small incident angles less than 0.015 radian, both codirectional isotropic self-diffraction (CODIS) and contradirectional isotropic self-diffraction (CONDIS) are generated simultaneously. At bigger incident angles approximately more than 0.2094 radian, only codirectional anisotropic-self diffraction (CODAS) are generated. On going imaging correlation is also showing.
Hanbury Brown-Twiss interferometry and second-order correlations of inflaton quanta
Giovannini, Massimo
2011-01-15
The quantum theory of optical coherence is applied to the scrutiny of the statistical properties of the relic inflaton quanta. After adapting the description of the quantized scalar and tensor modes of the geometry to the analysis of intensity correlations, the normalized degrees of first-order and second-order coherence are computed in the concordance paradigm and are shown to encode faithfully the statistical properties of the initial quantum state. The strongly bunched curvature phonons are not only super-Poissonian but also superchaotic. Testable inequalities are derived in the limit of large-angular scales and can be physically interpreted in the light of the tenets of Hanbury Brown-Twiss interferometry. The quantum mechanical results are compared and contrasted with different situations including the one where intensity correlations are the result of a classical stochastic process. The survival of second-order correlations (not necessarily related to the purity of the initial quantum state) is addressed by defining a generalized ensemble where super-Poissonian statistics is an intrinsic property of the density matrix and turns out to be associated with finite volume effects which are expected to vanish in the thermodynamic limit.
Wu, Zhenqin; Bi, Huimin; Pan, Sichen; Meng, Lingyi; Zhao, Xin Sheng
2016-11-17
Fluorescence correlation spectroscopy (FCS) is a powerful tool to investigate molecular diffusion and relaxations, which may be utilized to study many problems such as molecular size and aggregation, chemical reaction, molecular transportation and motion, and various kinds of physical and chemical relaxations. This article focuses on a problem related to using the relaxation term to study a reaction. If two species with different fluorescence photon emission efficiencies are connected by a reaction, the kinetic and equilibrium properties will be manifested in the relaxation term of the FCS curve. However, the conventional FCS alone cannot simultaneously determine the equilibrium constant (K) and the relative fluorescence brightness (Q), both of which are indispensable in the extraction of thermodynamic and kinetic information from the experimental data. To circumvent the problem, an assumption of Q = 0 is often made for the weak fluorescent species, which may lead to numerous errors when the actual situation is not the case. We propose to combine the third-order FCS with the conventional second-order FCS to determine K and Q without invoking other resources. The strategy and formalism are verified by computer simulations and demonstrated in a classical example of the hairpin DNA-folding process.
Misra, Avijit; Biswas, Anindya; Pati, Arun K; Sen De, Aditi; Sen, Ujjwal
2015-05-01
Quantum discord is a measure of quantum correlations beyond the entanglement-separability paradigm. It is conceptualized by using the von Neumann entropy as a measure of disorder. We introduce a class of quantum correlation measures as differences between total and classical correlations, in a shared quantum state, in terms of the sandwiched relative Rényi and Tsallis entropies. We compare our results with those obtained by using the traditional relative entropies. We find that the measures satisfy all the plausible axioms for quantum correlations. We evaluate the measures for shared pure as well as paradigmatic classes of mixed states. We show that the measures can faithfully detect the quantum critical point in the transverse quantum Ising model and find that they can be used to remove an unquieting feature of nearest-neighbor quantum discord in this respect. Furthermore, the measures provide better finite-size scaling exponents of the quantum critical point than the ones for other known order parameters, including entanglement and information-theoretic measures of quantum correlations.
NASA Astrophysics Data System (ADS)
Misra, Avijit; Biswas, Anindya; Pati, Arun K.; SenDe, Aditi; Sen, Ujjwal
2015-05-01
Quantum discord is a measure of quantum correlations beyond the entanglement-separability paradigm. It is conceptualized by using the von Neumann entropy as a measure of disorder. We introduce a class of quantum correlation measures as differences between total and classical correlations, in a shared quantum state, in terms of the sandwiched relative Rényi and Tsallis entropies. We compare our results with those obtained by using the traditional relative entropies. We find that the measures satisfy all the plausible axioms for quantum correlations. We evaluate the measures for shared pure as well as paradigmatic classes of mixed states. We show that the measures can faithfully detect the quantum critical point in the transverse quantum Ising model and find that they can be used to remove an unquieting feature of nearest-neighbor quantum discord in this respect. Furthermore, the measures provide better finite-size scaling exponents of the quantum critical point than the ones for other known order parameters, including entanglement and information-theoretic measures of quantum correlations.
Point model equations for neutron correlation counting: Extension of Böhnel's equations to any order
NASA Astrophysics Data System (ADS)
Favalli, Andrea; Croft, Stephen; Santi, Peter
2015-09-01
Various methods of autocorrelation neutron analysis may be used to extract information about a measurement item containing spontaneously fissioning material. The two predominant approaches being the time correlation analysis (that make use of a coincidence gate) methods of multiplicity shift register logic and Feynman sampling. The common feature is that the correlated nature of the pulse train can be described by a vector of reduced factorial multiplet rates. We call these singlets, doublets, triplets etc. Within the point reactor model the multiplet rates may be related to the properties of the item, the parameters of the detector, and basic nuclear data constants by a series of coupled algebraic equations - the so called point model equations. Solving, or inverting, the point model equations using experimental calibration model parameters is how assays of unknown items is performed. Currently only the first three multiplets are routinely used. In this work we develop the point model equations to higher order multiplets using the probability generating functions approach combined with the general derivative chain rule, the so called Faà di Bruno Formula. Explicit expression up to 5th order are provided, as well the general iterative formula to calculate any order. This work represents the first necessary step towards determining if higher order multiplets can add value to nondestructive measurement practice for nuclear materials control and accountancy.
Point model equations for neutron correlation counting: Extension of Böhnel's equations to any order
Favalli, Andrea; Croft, Stephen; Santi, Peter
2015-06-15
Various methods of autocorrelation neutron analysis may be used to extract information about a measurement item containing spontaneously fissioning material. The two predominant approaches being the time correlation analysis (that make use of a coincidence gate) methods of multiplicity shift register logic and Feynman sampling. The common feature is that the correlated nature of the pulse train can be described by a vector of reduced factorial multiplet rates. We call these singlets, doublets, triplets etc. Within the point reactor model the multiplet rates may be related to the properties of the item, the parameters of the detector, and basic nuclear data constants by a series of coupled algebraic equations – the so called point model equations. Solving, or inverting, the point model equations using experimental calibration model parameters is how assays of unknown items is performed. Currently only the first three multiplets are routinely used. In this work we develop the point model equations to higher order multiplets using the probability generating functions approach combined with the general derivative chain rule, the so called Faà di Bruno Formula. Explicit expression up to 5th order are provided, as well the general iterative formula to calculate any order. This study represents the first necessary step towards determining if higher order multiplets can add value to nondestructive measurement practice for nuclear materials control and accountancy.
Point model equations for neutron correlation counting: Extension of Böhnel's equations to any order
Favalli, Andrea; Croft, Stephen; Santi, Peter
2015-06-15
Various methods of autocorrelation neutron analysis may be used to extract information about a measurement item containing spontaneously fissioning material. The two predominant approaches being the time correlation analysis (that make use of a coincidence gate) methods of multiplicity shift register logic and Feynman sampling. The common feature is that the correlated nature of the pulse train can be described by a vector of reduced factorial multiplet rates. We call these singlets, doublets, triplets etc. Within the point reactor model the multiplet rates may be related to the properties of the item, the parameters of the detector, and basic nuclearmore » data constants by a series of coupled algebraic equations – the so called point model equations. Solving, or inverting, the point model equations using experimental calibration model parameters is how assays of unknown items is performed. Currently only the first three multiplets are routinely used. In this work we develop the point model equations to higher order multiplets using the probability generating functions approach combined with the general derivative chain rule, the so called Faà di Bruno Formula. Explicit expression up to 5th order are provided, as well the general iterative formula to calculate any order. This study represents the first necessary step towards determining if higher order multiplets can add value to nondestructive measurement practice for nuclear materials control and accountancy.« less
Interplay between Graph Topology and Correlations of Third Order in Spiking Neuronal Networks.
Jovanović, Stojan; Rotter, Stefan
2016-06-01
The study of processes evolving on networks has recently become a very popular research field, not only because of the rich mathematical theory that underpins it, but also because of its many possible applications, a number of them in the field of biology. Indeed, molecular signaling pathways, gene regulation, predator-prey interactions and the communication between neurons in the brain can be seen as examples of networks with complex dynamics. The properties of such dynamics depend largely on the topology of the underlying network graph. In this work, we want to answer the following question: Knowing network connectivity, what can be said about the level of third-order correlations that will characterize the network dynamics? We consider a linear point process as a model for pulse-coded, or spiking activity in a neuronal network. Using recent results from theory of such processes, we study third-order correlations between spike trains in such a system and explain which features of the network graph (i.e. which topological motifs) are responsible for their emergence. Comparing two different models of network topology-random networks of Erdős-Rényi type and networks with highly interconnected hubs-we find that, in random networks, the average measure of third-order correlations does not depend on the local connectivity properties, but rather on global parameters, such as the connection probability. This, however, ceases to be the case in networks with a geometric out-degree distribution, where topological specificities have a strong impact on average correlations.
Effects of high-order correlations on personalized recommendations for bipartite networks
NASA Astrophysics Data System (ADS)
Liu, Jian-Guo; Zhou, Tao; Che, Hong-An; Wang, Bing-Hong; Zhang, Yi-Cheng
2010-02-01
In this paper, we introduce a modified collaborative filtering (MCF) algorithm, which has remarkably higher accuracy than the standard collaborative filtering. In the MCF, instead of the cosine similarity index, the user-user correlations are obtained by a diffusion process. Furthermore, by considering the second-order correlations, we design an effective algorithm that depresses the influence of mainstream preferences. Simulation results show that the algorithmic accuracy, measured by the average ranking score, is further improved by 20.45% and 33.25% in the optimal cases of MovieLens and Netflix data. More importantly, the optimal value λ depends approximately monotonously on the sparsity of the training set. Given a real system, we could estimate the optimal parameter according to the data sparsity, which makes this algorithm easy to be applied. In addition, two significant criteria of algorithmic performance, diversity and popularity, are also taken into account. Numerical results show that as the sparsity increases, the algorithm considering the second-order correlation can outperform the MCF simultaneously in all three criteria.
Alparone, Andrea
2013-08-01
Dipole moments (μ), charge distributions, and static electronic first-order hyperpolarizabilities (β(μ)) of the two lowest-energy keto tautomers of guanine (7H and 9H) were determined in the gas phase using Hartree-Fock, Møller-Plesset perturbation theory (MP2 and MP4), and DFT (PBE1PBE, B97-1, B3LYP, CAM-B3LYP) methods with Dunning's correlation-consistent aug-cc-pVDZ and d-aug-cc-pVDZ basis sets. The most stable isomer 7H exhibits a μ value smaller than that of the 9H form by a factor of ca. 3.5. The β μ value of the 9H tautomer is strongly dependent on the computational method employed, as it dramatically influences the β(μ) (9H)/β(μ) (7H) ratio, which at the highest correlated MP4/aug-cc-pVDZ level is predicted to be ca. 5. The Coulomb-attenuating hybrid exchange-correlation CAM-B3LYP method is superior to the conventional PBE1PBE, B3LYP, and B97-1 functionals in predicting the β(μ) values. Differences between the largest diagonal hyperpolarizability components were clarified through hyperpolarizability density analyses. Dipole moment and first-order hyperpolarizability are molecular properties that are potentially useful for distinguishing the 7H from the 9H tautomer.
Oberer, Richard B.
2002-10-01
The current practice of nondestructive assay (NDA) of fissile materials using neutrons is dominated by the ^{3}He detector. This has been the case since the mid 1980s when Fission Multiplicity Detection (FMD) was replaced with thermal well counters and neutron multiplicity counting (NMC). The thermal well counters detect neutrons by neutron capture in the ^{3}He detector subsequent to moderation. The process of detection requires from 30 to 60 μs. As will be explained in Section 3.3 the rate of detecting correlated neutrons (signal) from the same fission are independent of this time but the rate of accidental correlations (noise) are proportional to this time. The well counters are at a distinct disadvantage when there is a large source of uncorrelated neutrons present from (α, n) reactions for example. Plastic scintillating detectors, as were used in FMD, require only about 20 ns to detect neutrons from fission. One thousandth as many accidental coincidences are therefore accumulated. The major problem with the use of fast-plastic scintillation detectors, however, is that both neutrons and gamma rays are detected. The pulses from the two are indistinguishable in these detectors. For this thesis, a new technique was developed to use higher-order time correlation statistics to distinguish combinations of neutron and gamma ray detections in fast-plastic scintillation detectors. A system of analysis to describe these correlations was developed based on simple physical principles. Other sources of correlations from non-fission events are identified and integrated into the analysis developed for fission events. A number of ratios and metric are identified to determine physical properties of the source from the correlations. It is possible to determine both the quantity being measured and detection efficiency from these ratios from a single measurement without a separate calibration. To account for detector dead-time, an alternative analytical technique
A generative spike train model with time-structured higher order correlations.
Trousdale, James; Hu, Yu; Shea-Brown, Eric; Josić, Krešimir
2013-01-01
Emerging technologies are revealing the spiking activity in ever larger neural ensembles. Frequently, this spiking is far from independent, with correlations in the spike times of different cells. Understanding how such correlations impact the dynamics and function of neural ensembles remains an important open problem. Here we describe a new, generative model for correlated spike trains that can exhibit many of the features observed in data. Extending prior work in mathematical finance, this generalized thinning and shift (GTaS) model creates marginally Poisson spike trains with diverse temporal correlation structures. We give several examples which highlight the model's flexibility and utility. For instance, we use it to examine how a neural network responds to highly structured patterns of inputs. We then show that the GTaS model is analytically tractable, and derive cumulant densities of all orders in terms of model parameters. The GTaS framework can therefore be an important tool in the experimental and theoretical exploration of neural dynamics.
A generative spike train model with time-structured higher order correlations
Trousdale, James; Hu, Yu; Shea-Brown, Eric; Josić, Krešimir
2013-01-01
Emerging technologies are revealing the spiking activity in ever larger neural ensembles. Frequently, this spiking is far from independent, with correlations in the spike times of different cells. Understanding how such correlations impact the dynamics and function of neural ensembles remains an important open problem. Here we describe a new, generative model for correlated spike trains that can exhibit many of the features observed in data. Extending prior work in mathematical finance, this generalized thinning and shift (GTaS) model creates marginally Poisson spike trains with diverse temporal correlation structures. We give several examples which highlight the model's flexibility and utility. For instance, we use it to examine how a neural network responds to highly structured patterns of inputs. We then show that the GTaS model is analytically tractable, and derive cumulant densities of all orders in terms of model parameters. The GTaS framework can therefore be an important tool in the experimental and theoretical exploration of neural dynamics. PMID:23908626
NASA Astrophysics Data System (ADS)
Aleiner, Igor L.; Faoro, Lara; Ioffe, Lev B.
2016-12-01
We extend the Keldysh technique to enable the computation of out-of-time order correlators such as < O(t) O ˜ (0) O(t) O ˜ (0) > . We show that the behavior of these correlators is described by equations that display initially an exponential instability which is followed by a linear propagation of the decoherence between two initially identically copies of the quantum many body systems with interactions. At large times the decoherence propagation (quantum butterfly effect) is described by a diffusion equation with non-linear dissipation known in the theory of combustion waves. The solution of this equation is a propagating non-linear wave moving with constant velocity despite the diffusive character of the underlying dynamics. Our general conclusions are illustrated by the detailed computations for the specific models describing the electrons interacting with bosonic degrees of freedom (phonons, two-level-systems etc.) or with each other.
Exact out-of-time-ordered correlation functions for an interacting lattice fermion model
NASA Astrophysics Data System (ADS)
Tsuji, Naoto; Werner, Philipp; Ueda, Masahito
2017-01-01
Exact solutions for local equilibrium and nonequilibrium out-of-time-ordered correlation (OTOC) functions are obtained for a lattice fermion model with on-site interactions, namely, the Falicov-Kimball (FK) model, in the large dimensional and thermodynamic limit. Our approach is based on the nonequilibrium dynamical mean-field theory generalized to an extended Kadanoff-Baym contour. We find that the density-density OTOC is most enhanced at intermediate coupling around the metal-insulator phase transition. In the high-temperature limit, the OTOC remains nontrivially finite and interaction dependent, even though dynamical charge correlations probed by an ordinary response function are completely suppressed. We propose an experiment to measure OTOCs of fermionic lattice systems including the FK and Hubbard models in ultracold atomic systems.
NASA Astrophysics Data System (ADS)
Böhmer, R.; Diezemann, G.; Hinze, G.; Sillescu, H.
1998-01-01
Using deuteron NMR techniques two-, effective three-, and various four-time correlation functions were recorded for supercooled ortho-terphenyl at 10-15 K above the calorimetric glass transition in order to characterize the heterogeneous nature of its primary response. The experimental results could successfully be described within various energy landscape models as well as via continuous time random walk simulations. These theoretical considerations provide a suitable basis for a definition of the term dynamic heterogeneity. We discuss the power but also some limitations of the present multidimensional NMR techniques when applied to amorphous materials.
Next-to-leading order perturbative QCD corrections to baryon correlators in matter
Groote, S.; Koerner, J. G.; Pivovarov, A. A.
2008-08-01
We compute the next-to-leading order (NLO) perturbative QCD corrections to the correlators of nucleon interpolating currents in relativistic nuclear matter. The main new result is the calculation of the O({alpha}{sub s}) perturbative corrections to the coefficient functions of the vector quark condensate in matter. This condensate appears in matter due to the violation of Lorentz invariance. The NLO perturbative QCD corrections turn out to be large which implies that the NLO corrections must be included in a sum rule analysis of the properties of both bound nucleons and relativistic nuclear matter.
Dasbiswas, K; Majkut, S; Discher, D E; Safran, Samuel A
2015-01-19
Recent experiments show that both striation, an indication of the structural registry in muscle fibres, as well as the contractile strains produced by beating cardiac muscle cells can be optimized by substrate stiffness. Here we show theoretically how the substrate rigidity dependence of the registry data can be mapped onto that of the strain measurements. We express the elasticity-mediated structural registry as a phase-order parameter using a statistical physics approach that takes the noise and disorder inherent in biological systems into account. By assuming that structurally registered myofibrils also tend to beat in phase, we explain the observed dependence of both striation and strain measurements of cardiomyocytes on substrate stiffness in a unified manner. The agreement of our ideas with experiment suggests that the correlated beating of heart cells may be limited by the structural order of the myofibrils, which in turn is regulated by their elastic environment.
Exploiting multi-lead electrocardiogram correlations using robust third-order tensor decomposition
Dandapat, Samarendra
2015-01-01
In this Letter, a robust third-order tensor decomposition of multi-lead electrocardiogram (MECG) comprising of 12-leads is proposed to reduce the dimension of the storage data. An order-3 tensor structure is employed to represent the MECG data by rearranging the MECG information in three dimensions. The three-dimensions of the formed tensor represent the number of leads, beats and samples of some fixed ECG duration. Dimension reduction of such an arrangement exploits correlations present among the successive beats (intra-beat and inter-beat) and across the leads (inter-lead). The higher-order singular value decomposition is used to decompose the tensor data. In addition, multiscale analysis has been added for effective care of ECG information. It grossly segments the ECG characteristic waves (P-wave, QRS-complex, ST-segment and T-wave etc.) into different sub-bands. In the meantime, it separates high-frequency noise components into lower-order sub-bands which helps in removing noise from the original data. For evaluation purposes, we have used the publicly available PTB diagnostic database. The proposed method outperforms the existing algorithms where compression ratio is under 10 for MECG data. Results show that the original MECG data volume can be reduced by more than 45 times with acceptable diagnostic distortion level. PMID:26609416
Topological order of mixed states in correlated quantum many-body systems
NASA Astrophysics Data System (ADS)
Grusdt, F.
2017-02-01
Topological order has become a new paradigm to distinguish ground states of interacting many-body systems without conventional long-range order. Here, we discuss possible extensions of this concept to density matrices describing statistical ensembles. For a large class of quasithermal states, which can be realized as thermal states of some quasilocal Hamiltonian, we generalize earlier definitions of density-matrix topology to generic many-body systems with strong correlations. We point out that the robustness of topological order, defined as a pattern of long-range entanglement, depends crucially on the perturbations under consideration. While it is intrinsically protected against local perturbations of arbitrary strength in an infinite closed quantum system, purely local perturbations can destroy topological order in open systems coupled to baths if the coupling is sufficiently strong. We discuss our classification scheme using the finite-temperature quantum Hall states and point out that the classical Hall effect can be understood as a finite-temperature topological phase.
Simulating superradiance from higher-order-intensity-correlation measurements: Single atoms
NASA Astrophysics Data System (ADS)
Wiegner, R.; Oppel, S.; Bhatti, D.; von Zanthier, J.; Agarwal, G. S.
2015-09-01
Superradiance typically requires preparation of atoms in highly entangled multiparticle states, the so-called Dicke states. In this paper we discuss an alternative route where we prepare such states from initially uncorrelated atoms by a measurement process. By measuring higher-order intensity-intensity correlations we demonstrate that we can simulate the emission characteristics of Dicke superradiance by starting with atoms in the fully excited state. We describe the essence of the scheme by first investigating two excited atoms. Here we demonstrate how via Hanbury Brown and Twiss type of measurements we can produce Dicke superradiance and subradiance displayed commonly with two atoms in the single excited symmetric and antisymmetric Dicke states, respectively. We thereafter generalize the scheme to arbitrary numbers of atoms and detectors, and explain in detail the mechanism which leads to this result. The approach shows that the Hanbury Brown and Twiss type of intensity interference and the phenomenon of Dicke superradiance can be regarded as two sides of the same coin. We also present a compact result for the characteristic functional which generates all order intensity-intensity correlations.
Cascade Error Projection with Low Bit Weight Quantization for High Order Correlation Data
NASA Technical Reports Server (NTRS)
Duong, Tuan A.; Daud, Taher
1998-01-01
In this paper, we reinvestigate the solution for chaotic time series prediction problem using neural network approach. The nature of this problem is such that the data sequences are never repeated, but they are rather in chaotic region. However, these data sequences are correlated between past, present, and future data in high order. We use Cascade Error Projection (CEP) learning algorithm to capture the high order correlation between past and present data to predict a future data using limited weight quantization constraints. This will help to predict a future information that will provide us better estimation in time for intelligent control system. In our earlier work, it has been shown that CEP can sufficiently learn 5-8 bit parity problem with 4- or more bits, and color segmentation problem with 7- or more bits of weight quantization. In this paper, we demonstrate that chaotic time series can be learned and generalized well with as low as 4-bit weight quantization using round-off and truncation techniques. The results show that generalization feature will suffer less as more bit weight quantization is available and error surfaces with the round-off technique are more symmetric around zero than error surfaces with the truncation technique. This study suggests that CEP is an implementable learning technique for hardware consideration.
Murg, V; Verstraete, F; Schneider, R; Nagy, P R; Legeza, Ö
2015-03-10
We study the tree-tensor-network-state (TTNS) method with variable tensor orders for quantum chemistry. TTNS is a variational method to efficiently approximate complete active space (CAS) configuration interaction (CI) wave functions in a tensor product form. TTNS can be considered as a higher order generalization of the matrix product state (MPS) method. The MPS wave function is formulated as products of matrices in a multiparticle basis spanning a truncated Hilbert space of the original CAS-CI problem. These matrices belong to active orbitals organized in a one-dimensional array, while tensors in TTNS are defined upon a tree-like arrangement of the same orbitals. The tree-structure is advantageous since the distance between two arbitrary orbitals in the tree scales only logarithmically with the number of orbitals N, whereas the scaling is linear in the MPS array. It is found to be beneficial from the computational costs point of view to keep strongly correlated orbitals in close vicinity in both arrangements; therefore, the TTNS ansatz is better suited for multireference problems with numerous highly correlated orbitals. To exploit the advantages of TTNS a novel algorithm is designed to optimize the tree tensor network topology based on quantum information theory and entanglement. The superior performance of the TTNS method is illustrated on the ionic-neutral avoided crossing of LiF. It is also shown that the avoided crossing of LiF can be localized using only ground state properties, namely one-orbital entanglement.
Reconstruction of noise-driven nonlinear networks from node outputs by using high-order correlations
Chen, Yang; Zhang, Zhaoyang; Chen, Tianyu; Wang, Shihong; Hu, Gang
2017-01-01
Many practical systems can be described by dynamic networks, for which modern technique can measure their outputs, and accumulate extremely rich data. Nevertheless, the network structures producing these data are often deeply hidden in the data. The problem of inferring network structures by analyzing the available data, turns to be of great significance. On one hand, networks are often driven by various unknown facts, such as noises. On the other hand, network structures of practical systems are commonly nonlinear, and different nonlinearities can provide rich dynamic features and meaningful functions of realistic networks. Although many works have considered each fact in studying network reconstructions, much less papers have been found to systematically treat both difficulties together. Here we propose to use high-order correlation computations (HOCC) to treat nonlinear dynamics; use two-time correlations to decorrelate effects of network dynamics and noise driving; and use suitable basis and correlator vectors to unifiedly infer all dynamic nonlinearities, topological interaction links and noise statistical structures. All the above theoretical frameworks are constructed in a closed form and numerical simulations fully verify the validity of theoretical predictions. PMID:28322230
Reconstruction of noise-driven nonlinear networks from node outputs by using high-order correlations
NASA Astrophysics Data System (ADS)
Chen, Yang; Zhang, Zhaoyang; Chen, Tianyu; Wang, Shihong; Hu, Gang
2017-03-01
Many practical systems can be described by dynamic networks, for which modern technique can measure their outputs, and accumulate extremely rich data. Nevertheless, the network structures producing these data are often deeply hidden in the data. The problem of inferring network structures by analyzing the available data, turns to be of great significance. On one hand, networks are often driven by various unknown facts, such as noises. On the other hand, network structures of practical systems are commonly nonlinear, and different nonlinearities can provide rich dynamic features and meaningful functions of realistic networks. Although many works have considered each fact in studying network reconstructions, much less papers have been found to systematically treat both difficulties together. Here we propose to use high-order correlation computations (HOCC) to treat nonlinear dynamics; use two-time correlations to decorrelate effects of network dynamics and noise driving; and use suitable basis and correlator vectors to unifiedly infer all dynamic nonlinearities, topological interaction links and noise statistical structures. All the above theoretical frameworks are constructed in a closed form and numerical simulations fully verify the validity of theoretical predictions.
Lyapunov Exponent and Out-of-Time-Ordered Correlator's Growth Rate in a Chaotic System
NASA Astrophysics Data System (ADS)
Rozenbaum, Efim B.; Ganeshan, Sriram; Galitski, Victor
2017-02-01
It was proposed recently that the out-of-time-ordered four-point correlator (OTOC) may serve as a useful characteristic of quantum-chaotic behavior, because, in the semiclassical limit ℏ→0 , its rate of exponential growth resembles the classical Lyapunov exponent. Here, we calculate the four-point correlator C (t ) for the classical and quantum kicked rotor—a textbook driven chaotic system—and compare its growth rate at initial times with the standard definition of the classical Lyapunov exponent. Using both quantum and classical arguments, we show that the OTOC's growth rate and the Lyapunov exponent are, in general, distinct quantities, corresponding to the logarithm of the phase-space averaged divergence rate of classical trajectories and to the phase-space average of the logarithm, respectively. The difference appears to be more pronounced in the regime of low kicking strength K , where no classical chaos exists globally. In this case, the Lyapunov exponent quickly decreases as K →0 , while the OTOC's growth rate may decrease much slower, showing a higher sensitivity to small chaotic islands in the phase space. We also show that the quantum correlator as a function of time exhibits a clear singularity at the Ehrenfest time tE: transitioning from a time-independent value of t-1ln C (t ) at t
N(th)-order correlation functions of galaxies from the Sloan Digital Sky Survey
NASA Astrophysics Data System (ADS)
Ross, Ashley Jacob
I present the correlation function measurements and analysis I have conducted with SDSS data. I have focused my measurements on angular N -point area- averaged correlation functions ( o N ([straight theta]) ) and auto-correlation functions (o 2 ([straight theta])) of galaxies. The measured o N ([straight theta]) are used to calculate the projected, s N , and real space, S N , hierarchical amplitudes. I have used SDSS DR3 data to show that the measurements are robust against the systematic effects of reddening and seeing, and to determine that large differences exist in the higher-order clustering of early- and late-type galaxies--quantified in terms of bias parameters. Using photometric redshift catalogs from SDSS DR5 data, I have created two volume limited samples of galaxies, allowing me to measure o N ([straight theta]) as a function of type, redshift, and luminosity. I have found that the higher-order bias of early-type galaxies does not vary significantly with changes in either redshift or luminosity, as c 2, early is consistent with 0.09 for all measurements. I have shown that the higher-order clustering of late-type galaxies shows dramatic differences for galaxies selected with redshifts above and below z = 0.3. Using LRGs photometrically selected from SDSS DR5, I have measured the 2nd-order bias tern, c 2 , using both o 2 ([straight theta]) and s 3 , and I have combined these measurements to determine that the normalization of the matter power spectrum at 8 h -1 Mpc, s 8 , is 0.79 ± 0.05 and c 2, LRG = 0.09 ± 0.04--consistent with the DR5 early-type results. I have calculated o 2 ([straight theta]) of galaxies from SDSS DR5 to constrain the HOD of galaxies as a function of type. I found that a new model that separated early- and late- type galaxies into different dark matter halos as much as possible was required to allow good fits to the measurements. Throughout, my findings are interpreted with respect to both the evolution of structure formation and
NASA Astrophysics Data System (ADS)
Jukić, Damir; Denić-Jukić, Vesna
2015-11-01
Time series of rainfall and karst-spring discharge are influenced by various space-time-variant processes involved in the transfer of water in hydrological cycle. The effects of these processes can be exhibited in auto-correlation and cross-correlation functions. Consequently, ambiguities with respect to the effects encoded in the correlation functions exist. To solve this problem, a new statistical method for investigating relationships between rainfall and karst-spring discharge is proposed. The method is based on the determination and analysis of higher-order partial correlation functions and their spectral representations. The study area is the catchment of the Jadro Spring in Croatia. The analyzed daily time series are the air temperature, relative humidity, spring discharge, and rainfall at seven rain-gauges over a period of 19 years, from 1995 to 2013. The application results show that the effects of spatial and temporal variations of hydrological time series and the space-time-variant behaviours of the karst system can be separated from the correlation functions. Specifically, the effect of evapotranspiration can be separated to obtain the forms of correlation functions that represent the hydrogeological characteristics of the karst system. Using the proposed method, it is also possible to separate the effects of the process of groundwater recharge that occurs in neighbouring parts of a catchment to identify the specific contribution of each part of the catchment to the karst-spring discharge. The main quantitative results obtained for the Jadro Spring show that the quick-flow duration is 14 days, the intermediate-flow duration is 80 days, and the pure base flow starts after 80 days. The base flow consists of an inter-catchment groundwater flow. The system memory of the spring is 80 days. The presented results indicate the far-reaching applicability of the proposed method in the analyses of relationships between rainfall and karst-spring discharge; e
Chandrasekaran, Naresh; Gann, Eliot; Jain, Nakul; Kumar, Anshu; Gopinathan, Sreelekha; Sadhanala, Aditya; Friend, Richard H; Kumar, Anil; McNeill, Christopher R; Kabra, Dinesh
2016-08-10
In this paper we correlate the solar cell performance with bimolecular packing of donor:acceptor bulk heterojunction (BHJ) organic solar cells (OSCs), where interchain ordering of the donor molecule and its influence on morphology, optical properties, and charge carrier dynamics of BHJ solar cells are studied in detail. Solar cells that are fabricated using more ordered defect free 100% regioregular poly(3-hexylthiophene) (DF-P3HT) as the donor polymer show ca. 10% increase in the average power conversion efficiency (PCE) when compared to that of the solar cell fabricated using 92% regioregularity P3HT, referred to as rr-P3HT. EQE and UV-vis absorption spectrum show a clear increase in the 607 nm vibronic shoulder of the DF-P3HT blend suggesting better interchain ordering which was also reflected in the less Urbach energy (Eu) value for this system. The increase in ordering inside the blend has enhanced the hole-mobility which is calculated from the single carrier device J-V characteristics. Electroluminance (EL) studies on the DF-P3HT system showed a red-shifted peak when compared to rr-P3HT-based devices suggesting low CT energy states in DF-P3HT. The morphologies of the blend films are studied using AFM and grazing-incidence wide-angle X-ray scattering (GIWAXS) suggesting increase in the roughness and phase segregation which could enhance the internal scattering of the light inside the device and improvement in the crystallinity along alkyl and π-stacking direction. Hence, higher PCE, lower Eu, red-shifted EL emission, high hole-mobility, and better crystallinity suggest improved interchain ordering has facilitated a more delocalized HOMO state in DF-P3HT-based BHJ solar cells.
Bias and high-order galaxy correlation functions in the APM galaxy survey
NASA Technical Reports Server (NTRS)
Gaztanaga, Enrique; Frieman, Joshua A.
1994-01-01
On large scales, the higher order moments of the mass distribution, S(sub J) = bar-zeta(sub J)/bar-zeta(sup J-1)(sub 2), e.g., the skewness S(sub 3) and kurtosis S(sub 4), can be predicted using nonlinear perturbation theory. Comparison of these predictions with moments of the observed galaxy distribution probes the bias between galaxies and mass. Applying this method to models with initially Gaussian fluctuations and power spectra P(k) similar to that of galaxies in the Automatic Plate Measuring (APM) survey, we find that the predicted higher order moments S(sub J)(R) are in good agreement with those directly inferred from the APM survey in the absence of bias. We use this result to place limits on the linear and nonlinear bias parameters. Models in which the extra power observed on large scales (with respect to the standard cold dark matter (CDM) model) is produced by scale-dependent bias match the APM higher order amplitudes only if nonlinear bias (rather than nonlinear gravity) generates the observed higher order moments. When normalized to Cosmic Background Explorer Differential Microwave Radiometer (COBE DMR), these models are siginificantly ruled out by the S(sub 3) observations. The cold plus hot dark matter model normalized to COBE can reproduce the APM higher order correlations if one introduces nonlinear bias terms, while the low-density CDM model with a cosmological constant does not require any bias to fit the large-scale amplitudes.
NASA Astrophysics Data System (ADS)
Müller, Clemens; Stace, Thomas M.
2017-01-01
Motivated by correlated decay processes producing gain, loss, and lasing in driven semiconductor quantum dots [Phys. Rev. Lett. 113, 036801 (2014), 10.1103/PhysRevLett.113.036801; Science 347, 285 (2015), 10.1126/science.aaa2501; Phys. Rev. Lett. 114, 196802 (2015), 10.1103/PhysRevLett.114.196802], we develop a theoretical technique by using Keldysh diagrammatic perturbation theory to derive a Lindblad master equation that goes beyond the usual second-order perturbation theory. We demonstrate the method on the driven dissipative Rabi model, including terms up to fourth order in the interaction between the qubit and both the resonator and environment. This results in a large class of Lindblad dissipators and associated rates which go beyond the terms that have previously been proposed to describe similar systems. All of the additional terms contribute to the system behavior at the same order of perturbation theory. We then apply these results to analyze the phonon-assisted steady-state gain of a microwave field driving a double quantum dot in a resonator. We show that resonator gain and loss are substantially affected by dephasing-assisted dissipative processes in the quantum-dot system. These additional processes, which go beyond recently proposed polaronic theories, are in good quantitative agreement with experimental observations.
Jarzynski-like equality for the out-of-time-ordered correlator
NASA Astrophysics Data System (ADS)
Yunger Halpern, Nicole
2017-01-01
The out-of-time-ordered correlator (OTOC) diagnoses quantum chaos and the scrambling of quantum information via the spread of entanglement. The OTOC encodes forward and reverse evolutions and has deep connections with the flow of time. So do fluctuation relations such as Jarzynski's equality, derived in nonequilibrium statistical mechanics. I unite these two powerful, seemingly disparate tools by deriving a Jarzynski-like equality for the OTOC. The equality's left-hand side equals the OTOC. The right-hand side suggests a protocol for measuring the OTOC indirectly. The protocol is platform-nonspecific and can be performed with weak measurement or with interference. Time evolution need not be reversed in any interference trial. The equality enables fluctuation relations to provide insights into holography, condensed matter, and quantum information and vice versa.
First-order melting of a weak spin-orbit mott insulator into a correlated metal
Hogan, Tom; Yamani, Z.; Walkup, D.; Chen, Xiang; Dally, Rebecca; Ward, Thomas Zac; Dean, M. P. M.; Hill, John P.; Islam, Z.; Madhavan, Vidya; Wilson, Stephen D.
2015-06-25
Herein, the electronic phase diagram of the weak spin-orbit Mott insulator (Sr_{1-x}La_{x})_{3}Ir_{2}O_{7} is determined via an exhaustive experimental study. Upon doping electrons via La substitution, an immediate collapse in resistivity occurs along with a narrow regime of nanoscale phase separation comprised of antiferromagnetic, insulating regions and paramagnetic, metallic puddles persisting until x≈0.04. Continued electron doping results in an abrupt, first-order phase boundary where the Néel state is suppressed and a homogenous, correlated, metallic state appears with an enhanced spin susceptibility and local moments. In conclusion, as the metallic state is stabilized, a weak structural distortion develops and suggests a competing instability with the parent spin-orbit Mott state.
First-order melting of a weak spin-orbit mott insulator into a correlated metal
Hogan, Tom; Yamani, Z.; Walkup, D.; ...
2015-06-25
Herein, the electronic phase diagram of the weak spin-orbit Mott insulator (Sr1-xLax)3Ir2O7 is determined via an exhaustive experimental study. Upon doping electrons via La substitution, an immediate collapse in resistivity occurs along with a narrow regime of nanoscale phase separation comprised of antiferromagnetic, insulating regions and paramagnetic, metallic puddles persisting until x≈0.04. Continued electron doping results in an abrupt, first-order phase boundary where the Néel state is suppressed and a homogenous, correlated, metallic state appears with an enhanced spin susceptibility and local moments. In conclusion, as the metallic state is stabilized, a weak structural distortion develops and suggests a competingmore » instability with the parent spin-orbit Mott state.« less
Explicitly correlated atomic orbital basis second order Møller-Plesset theory.
Hollman, David S; Wilke, Jeremiah J; Schaefer, Henry F
2013-02-14
The scope of problems treatable by ab initio wavefunction methods has expanded greatly through the application of local approximations. In particular, atomic orbital (AO) based wavefunction methods have emerged as powerful techniques for exploiting sparsity and have been applied to biomolecules as large as 1707 atoms [S. A. Maurer, D. S. Lambrecht, D. Flaig, and C. Ochsenfeld, J. Chem. Phys. 136, 144107 (2012)]. Correlated wavefunction methods, however, converge notoriously slowly to the basis set limit and, excepting the use of large basis sets, will suffer from a severe basis set incompleteness error (BSIE). The use of larger basis sets is prohibitively expensive for AO basis methods since, for example, second-order Møller-Plesset perturbation theory (MP2) scales linearly with the number of atoms, but still scales as O(N(5)) in the number of functions per atom. Explicitly correlated F12 methods have been shown to drastically reduce BSIE for even modestly sized basis sets. In this work, we therefore explore an atomic orbital based formulation of explicitly correlated MP2-F12 theory. We present working equations for the new method, which produce results identical to the widely used molecular orbital (MO) version of MP2-F12 without resorting to a delocalized MO basis. We conclude with a discussion of several possible approaches to a priori screening of contraction terms in our method and the prospects for a linear scaling implementation of AO-MP2-F12. The discussion includes concrete examples involving noble gas dimers and linear alkane chains.
Doping-dependent charge order correlations in electron-doped cuprates
da Silva Neto, Eduardo H.; Yu, Biqiong; Minola, Matteo; Sutarto, Ronny; Schierle, Enrico; Boschini, Fabio; Zonno, Marta; Bluschke, Martin; Higgins, Joshua; Li, Yangmu; Yu, Guichuan; Weschke, Eugen; He, Feizhou; Le Tacon, Mathieu; Greene, Richard L.; Greven, Martin; Sawatzky, George A.; Keimer, Bernhard; Damascelli, Andrea
2016-01-01
Understanding the interplay between charge order (CO) and other phenomena (for example, pseudogap, antiferromagnetism, and superconductivity) is one of the central questions in the cuprate high-temperature superconductors. The discovery that similar forms of CO exist in both hole- and electron-doped cuprates opened a path to determine what subset of the CO phenomenology is universal to all the cuprates. We use resonant x-ray scattering to measure the CO correlations in electron-doped cuprates (La2−xCexCuO4 and Nd2−xCexCuO4) and their relationship to antiferromagnetism, pseudogap, and superconductivity. Detailed measurements of Nd2−xCexCuO4 show that CO is present in the x = 0.059 to 0.166 range and that its doping-dependent wave vector is consistent with the separation between straight segments of the Fermi surface. The CO onset temperature is highest between x = 0.106 and 0.166 but decreases at lower doping levels, indicating that it is not tied to the appearance of antiferromagnetic correlations or the pseudogap. Near optimal doping, where the CO wave vector is also consistent with a previously observed phonon anomaly, measurements of the CO below and above the superconducting transition temperature, or in a magnetic field, show that the CO is insensitive to superconductivity. Overall, these findings indicate that, although verified in the electron-doped cuprates, material-dependent details determine whether the CO correlations acquire sufficient strength to compete for the ground state of the cuprates. PMID:27536726
Davis, J C Séamus; Lee, Dung-Hai
2013-10-29
Unconventional superconductivity (SC) is said to occur when Cooper pair formation is dominated by repulsive electron-electron interactions, so that the symmetry of the pair wave function is other than an isotropic s-wave. The strong, on-site, repulsive electron-electron interactions that are the proximate cause of such SC are more typically drivers of commensurate magnetism. Indeed, it is the suppression of commensurate antiferromagnetism (AF) that usually allows this type of unconventional superconductivity to emerge. Importantly, however, intervening between these AF and SC phases, intertwined electronic ordered phases (IP) of an unexpected nature are frequently discovered. For this reason, it has been extremely difficult to distinguish the microscopic essence of the correlated superconductivity from the often spectacular phenomenology of the IPs. Here we introduce a model conceptual framework within which to understand the relationship between AF electron-electron interactions, IPs, and correlated SC. We demonstrate its effectiveness in simultaneously explaining the consequences of AF interactions for the copper-based, iron-based, and heavy-fermion superconductors, as well as for their quite distinct IPs.
Davis, J. C. Séamus; Lee, Dung-Hai
2013-01-01
Unconventional superconductivity (SC) is said to occur when Cooper pair formation is dominated by repulsive electron–electron interactions, so that the symmetry of the pair wave function is other than an isotropic s-wave. The strong, on-site, repulsive electron–electron interactions that are the proximate cause of such SC are more typically drivers of commensurate magnetism. Indeed, it is the suppression of commensurate antiferromagnetism (AF) that usually allows this type of unconventional superconductivity to emerge. Importantly, however, intervening between these AF and SC phases, intertwined electronic ordered phases (IP) of an unexpected nature are frequently discovered. For this reason, it has been extremely difficult to distinguish the microscopic essence of the correlated superconductivity from the often spectacular phenomenology of the IPs. Here we introduce a model conceptual framework within which to understand the relationship between AF electron–electron interactions, IPs, and correlated SC. We demonstrate its effectiveness in simultaneously explaining the consequences of AF interactions for the copper-based, iron-based, and heavy-fermion superconductors, as well as for their quite distinct IPs. PMID:24114268
NASA Astrophysics Data System (ADS)
Diercksen, G. H. F.; Sadlej, A. J.
1981-08-01
The many-body perturbation theory is applied for the calculation of the second- and third-order correlation corrections to the SCF HF dipole moments and polarizabilities of FH, H2O, NH3, and CH4. All calculations are performed by using the finite-field perturbation approach. The pertinent correlation corrections follow from the numerical differentiation of the second- and third-order field-dependent correlation energies. This computational scheme corresponds to a completely self-consistent treatment of the perturbation effects. The third-order corrected dipole moments are in excellent agreement with the experimental data and the best results of other authors. A comparison of the present perturbation corrections for polarizabilities with the PNO-CI and CEPA results of Werner and Meyer reveals that some cancellation of the third- and fourth-order correlation contributions can be expected. The second-order corrected polarizabilities are as a rule better than the results of the third-order perturbation approach. It is concluded that also for polarizabilities the low-order many-body perturbation scheme is able to account for the major portion of the relevant correlation effects.
Correlation of structural order, anomalous density, and hydrogen bonding network of liquid water.
Bandyopadhyay, Dibyendu; Mohan, S; Ghosh, S K; Choudhury, Niharendu
2013-07-25
We use extensive molecular dynamics simulations employing different state-of-the-art force fields to find a common framework for comparing structural orders and density anomalies as obtained from different water models. It is found that the average number of hydrogen bonds correlates well with various order parameters as well as the temperature of maximum densities across the different models, unifying apparently disparate results from different models and emphasizing the importance of hydrogen bonding in determining anomalous properties and the structure of water. A deeper insight into the hydrogen bond network of water reveals that the solvation shell of a water molecule can be defined by considering only those neighbors that are hydrogen-bonded to it. On the basis of this view, the origin of the appearance of a non-tetrahedral peak at a higher temperature in the distribution of tetrahedral order parameters has been explained. It is found that a neighbor that is hydrogen-bonded to the central molecule is tetrahedrally coordinated even at higher temperatures. The non-tetrahedral peak at a higher temperature arises due to the strained orientation of the neighbors that are non-hydrogen-bonded to the central molecule. With the new definition of the solvation shell, liquid water can be viewed as an instantaneously changing random hydrogen-bonded network consisting of differently coordinated hydrogen-bonded molecules with their distinct solvation shells. The variation of the composition of these hydrogen-bonded molecules against temperature accounts for the density anomaly without introducing the concept of large-scale structural polyamorphism in water.
Monte Carlo explicitly correlated second-order many-body perturbation theory
NASA Astrophysics Data System (ADS)
Johnson, Cole M.; Doran, Alexander E.; Zhang, Jinmei; Valeev, Edward F.; Hirata, So
2016-10-01
A stochastic algorithm is proposed and implemented that computes a basis-set-incompleteness (F12) correction to an ab initio second-order many-body perturbation energy as a short sum of 6- to 15-dimensional integrals of Gaussian-type orbitals, an explicit function of the electron-electron distance (geminal), and its associated excitation amplitudes held fixed at the values suggested by Ten-no. The integrals are directly evaluated (without a resolution-of-the-identity approximation or an auxiliary basis set) by the Metropolis Monte Carlo method. Applications of this method to 17 molecular correlation energies and 12 gas-phase reaction energies reveal that both the nonvariational and variational formulas for the correction give reliable correlation energies (98% or higher) and reaction energies (within 2 kJ mol-1 with a smaller statistical uncertainty) near the complete-basis-set limits by using just the aug-cc-pVDZ basis set. The nonvariational formula is found to be 2-10 times less expensive to evaluate than the variational one, though the latter yields energies that are bounded from below and is, therefore, slightly but systematically more accurate for energy differences. Being capable of using virtually any geminal form, the method confirms the best overall performance of the Slater-type geminal among 6 forms satisfying the same cusp conditions. Not having to precompute lower-dimensional integrals analytically, to store them on disk, or to transform them in a nonscalable dense-matrix-multiplication algorithm, the method scales favorably with both system size and computer size; the cost increases only as O(n4) with the number of orbitals (n), and its parallel efficiency reaches 99.9% of the ideal case on going from 16 to 4096 computer processors.
Wang, Xiao; Broch, Katharina; Scholz, Reinhard; Schreiber, Frank; Meixner, Alfred J; Zhang, Dai
2014-04-03
Cylindrical vector beams, such as radially or azimuthally polarized doughnut beams, are combined with topography studies of pentacene thin films, allowing us to correlate Raman spectroscopy with intermolecular interactions depending on the particular pentacene polymorph. Polarization-dependent Raman spectra of the C-H bending vibrations are resolved layer by layer within a thin film of ∼20 nm thickness. The variation of the Raman peak positions indicates changes in the molecular orientation and in the local environment at different heights of the pentacene film. With the assistance of a theoretical model based on harmonic oscillator and perturbation theory, our method reveals the local structural order and the polymorph at different locations within the same pentacene thin film, depending mainly on its thickness. In good agreement with the crystallographic structures reported in the literature, our observations demonstrate that the first few monolayers grown in a structure are closer to the thin-film phase, but for larger film thicknesses, the morphology evolves toward the crystal-bulk phase with a larger tilting angle of the pentacene molecules against the substrate normal.
NASA Astrophysics Data System (ADS)
Atkinson, Steven; Stillinger, Frank H.; Torquato, Salvatore
2016-09-01
The nonequilibrium process by which hard-particle systems may be compressed into disordered, jammed states has received much attention because of its wide utility in describing a broad class of amorphous materials. While dynamical signatures are known to precede jamming, the task of identifying static structural signatures indicating the onset of jamming have proven more elusive. The observation that compressing hard-particle packings towards jamming is accompanied by an anomalous suppression of density fluctuations (termed "hyperuniformity") has paved the way for the analysis of jamming as an "inverted critical point" in which the direct correlation function c (r ) , rather than the total correlation function h (r ) , diverges. We expand on the notion that c (r ) provides both universal and protocol-specific information as packings approach jamming. By considering the degree and position of singularities (discontinuities in the n th derivative) as well as how they are changed by the convolutions found in the Ornstein-Zernike equation, we establish quantitative statements about the structure of c (r ) with regards to singularities it inherits from h (r ) . These relations provide a concrete means of identifying features that must be expressed in c (r ) if one hopes to reproduce various details in the pair correlation function accurately and provide stringent tests on the associated numerics. We also analyze the evolution of systems of three-dimensional monodisperse hard spheres of diameter D as they approach ordered and disordered jammed configurations. For the latter, we use the Lubachevsky-Stillinger (LS) molecular dynamics and Torquato-Jiao (TJ) sequential linear programming algorithms, which both generate disordered packings, but can show perceptible structural differences. We identify a short-ranged scaling c (r )∝-1 /r as r →0 that accompanies the formation of the delta function at c (D ) that indicates the formation of contacts in all cases, and show
Atkinson, Steven; Stillinger, Frank H; Torquato, Salvatore
2016-09-01
The nonequilibrium process by which hard-particle systems may be compressed into disordered, jammed states has received much attention because of its wide utility in describing a broad class of amorphous materials. While dynamical signatures are known to precede jamming, the task of identifying static structural signatures indicating the onset of jamming have proven more elusive. The observation that compressing hard-particle packings towards jamming is accompanied by an anomalous suppression of density fluctuations (termed "hyperuniformity") has paved the way for the analysis of jamming as an "inverted critical point" in which the direct correlation function c(r), rather than the total correlation function h(r), diverges. We expand on the notion that c(r) provides both universal and protocol-specific information as packings approach jamming. By considering the degree and position of singularities (discontinuities in the nth derivative) as well as how they are changed by the convolutions found in the Ornstein-Zernike equation, we establish quantitative statements about the structure of c(r) with regards to singularities it inherits from h(r). These relations provide a concrete means of identifying features that must be expressed in c(r) if one hopes to reproduce various details in the pair correlation function accurately and provide stringent tests on the associated numerics. We also analyze the evolution of systems of three-dimensional monodisperse hard spheres of diameter D as they approach ordered and disordered jammed configurations. For the latter, we use the Lubachevsky-Stillinger (LS) molecular dynamics and Torquato-Jiao (TJ) sequential linear programming algorithms, which both generate disordered packings, but can show perceptible structural differences. We identify a short-ranged scaling c(r)∝-1/r as r→0 that accompanies the formation of the delta function at c(D) that indicates the formation of contacts in all cases, and show that this scaling
NASA Astrophysics Data System (ADS)
Sugimoto, Toshiki; Aiga, Norihiro; Otsuki, Yuji; Watanabe, Kazuya; Matsumoto, Yoshiyasu
2016-11-01
Materials containing strong correlation and frustration have the potential to respond to external perturbations in an unusual way. In the case of common water ice, protons in the hydrogen-bond network are strongly correlated and highly frustrated under Pauling's ice rules. At low temperature, the strongly correlated protons lose ergodicity, and little is understood about the cooperative thermodynamic and electric response to external stimuli. Here, using a model platinum substrate, we demonstrate emergent high-Tc ferroelectric proton ordering in a heteroepitaxial ice film. Such proton ordering is thermodynamically stable and has an extremely high critical temperature of ~175 K. We found that anisotropy and protolysis driven by the electrostatistics at the heterointerface are key factors in stimulating this novel exotic ordering in the many-body correlated proton system. The significant increase in Tc due to the heterointerface suggests the ubiquity of ferroelectric ice in nature--specifically, in space and the polar stratosphere.
Montangie, Lisandro; Montani, Fernando
2016-10-01
Spike correlations among neurons are widely encountered in the brain. Although models accounting for pairwise interactions have proved able to capture some of the most important features of population activity at the level of the retina, the evidence shows that pairwise neuronal correlation analysis does not resolve cooperative population dynamics by itself. By means of a series expansion for short time scales of the mutual information conveyed by a population of neurons, the information transmission can be broken down into firing rate and correlational components. In a proposed extension of this framework, we investigate the information components considering both second- and higher-order correlations. We show that the existence of a mixed stimulus-dependent correlation term defines a new scenario for the interplay between pairwise and higher-than-pairwise interactions in noise and signal correlations that would lead either to redundancy or synergy in the information-theoretic sense.
NASA Astrophysics Data System (ADS)
Montangie, Lisandro; Montani, Fernando
2016-10-01
Spike correlations among neurons are widely encountered in the brain. Although models accounting for pairwise interactions have proved able to capture some of the most important features of population activity at the level of the retina, the evidence shows that pairwise neuronal correlation analysis does not resolve cooperative population dynamics by itself. By means of a series expansion for short time scales of the mutual information conveyed by a population of neurons, the information transmission can be broken down into firing rate and correlational components. In a proposed extension of this framework, we investigate the information components considering both second- and higher-order correlations. We show that the existence of a mixed stimulus-dependent correlation term defines a new scenario for the interplay between pairwise and higher-than-pairwise interactions in noise and signal correlations that would lead either to redundancy or synergy in the information-theoretic sense.
NASA Technical Reports Server (NTRS)
Mcclelland, J.; Silk, J.
1978-01-01
Higher-order correlation functions for the large-scale distribution of galaxies in space are investigated. It is demonstrated that the three-point correlation function observed by Peebles and Groth (1975) is not consistent with a distribution of perturbations that at present are randomly distributed in space. The two-point correlation function is shown to be independent of how the perturbations are distributed spatially, and a model of clustered perturbations is developed which incorporates a nonuniform perturbation distribution and which explains the three-point correlation function. A model with hierarchical perturbations incorporating the same nonuniform distribution is also constructed; it is found that this model also explains the three-point correlation function, but predicts different results for the four-point and higher-order correlation functions than does the model with clustered perturbations. It is suggested that the model of hierarchical perturbations might be explained by the single assumption of having density fluctuations or discrete objects all of the same mass randomly placed at some initial epoch.
NASA Astrophysics Data System (ADS)
Huang, Haiping
2017-03-01
To understand the collective spiking activity in neuronal populations, it is essential to reveal basic circuit variables responsible for these emergent functional states. Here, I develop a mean field theory for the population coupling recently proposed in the studies of the visual cortex of mouse and monkey, relating the individual neuron activity to the population activity, and extend the original form to the second order, relating neuron-pair’s activity to the population activity, to explain the high order correlations observed in the neural data. I test the computational framework on the salamander retinal data and the cortical spiking data of behaving rats. For the retinal data, the original form of population coupling and its advanced form can explain a significant fraction of two-cell correlations and three-cell correlations, respectively. For the cortical data, the performance becomes much better, and the second order population coupling reveals non-local effects in local cortical circuits.
Maslen, P.E.; Head-Gordon, M.
1998-11-01
We extend our noniterative local correlation method [P. E. Maslen and M. Head-Gordon, Chem. Phys. Lett., {bold 283}, 102 (1998)] by defining a hierarchy of local spaces, ranging from small to large. The accuracy of the local method is then examined as a function of the size of the local space. A medium size local space recovers 98{percent} of the MP2 correlation energy, and reproduces fine details of the potential energy surface such as rotational barriers with an RMS error of 0.2 kcal/mol and a maximum error of 0.4 kcal/mol. A large local space recovers 99.5{percent} of the correlation energy and yields rotational barriers with a RMS error of 0.05 kcal/mol and a maximum error of 0.1 kcal/mol, at significantly increased computational cost. {copyright} {ital 1998 American Institute of Physics.}
Grafting of higher-order correlations of real financial markets into herding models
NASA Astrophysics Data System (ADS)
Ahn, Sanghyun; Lim, Gyuchang; Kim, Sooyong; Kim, Kyungsik
2009-08-01
In this work, we graft the volatility clustering observed in empirical financial time series into the Equiluz and Zimmermann (EZ) model, which was introduced to reproduce the herding behaviors of a financial time series. The original EZ model failed to reproduce the empirically observed power-law exponents of real financial data. The EZ model ordinarily produces a more fat-tailed distribution compared to real data, and a long-range correlation of absolute returns that underlie the volatility clustering. As it is not appropriate to capture the empirically observed correlations in a modified EZ model, we apply a sorting method to incorporate the nonlinear correlation structure of a real financial time series into the generated returns. By doing so, we observe that the slow convergence of distribution of returns is well established for returns generated from the EZ model and its modified version. It is also found that the modified EZ model leads to a less fat-tailed distribution.
Shimazaki, Hideaki; Amari, Shun-Ichi; Brown, Emery N; Grün, Sonja
2012-01-01
Precise spike coordination between the spiking activities of multiple neurons is suggested as an indication of coordinated network activity in active cell assemblies. Spike correlation analysis aims to identify such cooperative network activity by detecting excess spike synchrony in simultaneously recorded multiple neural spike sequences. Cooperative activity is expected to organize dynamically during behavior and cognition; therefore currently available analysis techniques must be extended to enable the estimation of multiple time-varying spike interactions between neurons simultaneously. In particular, new methods must take advantage of the simultaneous observations of multiple neurons by addressing their higher-order dependencies, which cannot be revealed by pairwise analyses alone. In this paper, we develop a method for estimating time-varying spike interactions by means of a state-space analysis. Discretized parallel spike sequences are modeled as multi-variate binary processes using a log-linear model that provides a well-defined measure of higher-order spike correlation in an information geometry framework. We construct a recursive Bayesian filter/smoother for the extraction of spike interaction parameters. This method can simultaneously estimate the dynamic pairwise spike interactions of multiple single neurons, thereby extending the Ising/spin-glass model analysis of multiple neural spike train data to a nonstationary analysis. Furthermore, the method can estimate dynamic higher-order spike interactions. To validate the inclusion of the higher-order terms in the model, we construct an approximation method to assess the goodness-of-fit to spike data. In addition, we formulate a test method for the presence of higher-order spike correlation even in nonstationary spike data, e.g., data from awake behaving animals. The utility of the proposed methods is tested using simulated spike data with known underlying correlation dynamics. Finally, we apply the methods
Phase dependence of the unnormalized second-order photon correlation function
NASA Astrophysics Data System (ADS)
Ciornea, V.; Bardetski, P.; Macovei, M. A.
2016-10-01
We investigate the resonant quantum dynamics of a multi-qubit ensemble in a microcavity. Both the quantum-dot subsystem and the microcavity mode are pumped coherently. We find that the microcavity photon statistics depends on the phase difference of the driving lasers, which is not the case for the photon intensity at resonant driving. This way, one can manipulate the two-photon correlations. In particular, higher degrees of photon correlations and, eventually, stronger intensities are obtained. Furthermore, the microcavity photon statistics exhibits steady-state oscillatory behaviors as well as asymmetries.
NASA Astrophysics Data System (ADS)
Burger, J. P.; Daou, J. N.; Vajda, P.
1990-12-01
The excess hydrogen concentration x has fundamental effects on the magnetic properties which are due to modification of the conduction electron density and the shape of the Fermi surface, to crystal field effects and to order-disorder transitions within the H sublattice. We discuss: i) the occurrence of commensurate (for x = 0) and non-commensurate (for x > 0) antiferromagnetic ordering; ii) the effects of the crystal field which give rise to a non-Kondo resistivity minimum for PrH 2; iii) the incoherent and coherent Kondo effects of CeH 2+x and its relation with magnetism and structural ordering.
Ordering of self-assembled nanobiominerals in correlation to mechanical properties of hard tissues
Jiang Huaidong; Liu Xiangyang; Lim, Chwee T.; Hsu, Chin Y.
2005-04-18
Biominerals in the hard tissues of many organisms exhibit superior mechanical properties due to their unique hierarchical nanostructures. In this article, we show the microstructure of human tooth enamel examined by position-resolved small-angle x-ray scattering and electron microscopy. It is found that the degree of ordering of the biominerals varies strikingly within the dental sample. Combined with nanoindentation, our results show that both the hardness and the elastic modulus increase predominantly with the ordering of the biomineral crystallites. This can be attributed to the fact that the ordered structure helps sustain a more complex mechanical stress.
“Pure chaotic” orbits of one-dimensional maps have third-order correlation
NASA Astrophysics Data System (ADS)
Tsuchiya, Takashi; Ichimura, Atsushi
1984-04-01
The triple-time-correlation function for the logistic map and the tent map, both for the uppermost values of their parameters, are calculated analytically and orbits of these systems are shown to be different from a pseudo-random-number sequence generated on a computer. Violation of the time-reversal invariance by these orbits is also discussed.
NASA Astrophysics Data System (ADS)
Buranasiri, Prathan; Banerjee, Partha P.; Polejaev, Vladimir; Sun, Ching-Cherng
2003-10-01
Using two beam coupling geometry, high order copropagating and contrapropagating isotropic and copropagating anisotropic self-diffraction are demonstrated using photorefractive cerium doped barium titanate. At small incident angles, typically less than 0.015 radians, both codirectional isotropic self-diffraction (CODIS) and contradirectional isotropic self-diffraction (CONDIS) orders are generated simultaneously. At larger incident angles, typically approximately more than 0.2094 radians, only codirectional anisotropic-self diffraction (CODAS) orders are generated. Ongoing work on image auto/cross correlation results are also shown.
Neural correlates of tactile temporal-order judgment in humans: an fMRI study.
Takahashi, Toshimitsu; Kansaku, Kenji; Wada, Makoto; Shibuya, Satoshi; Kitazawa, Shigeru
2013-08-01
Little is known about the neuronal mechanisms underlying the temporal ordering of tactile signals. We examined the brain regions involved in judgments of the temporal order of successive taps delivered to both hands. Participants received identical stimuli while engaging in 2 different tasks: Judging the temporal order and judging the numerosity of points of tactile stimulation. Comparisons of the functional magnetic resonance imaging data obtained during the 2 tasks revealed regions that were more strongly activated with the judgments of the temporal order than with the judgments of numerosity under both arms-uncrossed and -crossed conditions: The bilateral premotor cortices, the bilateral middle frontal gyri, the bilateral inferior parietal cortices and supramarginal gyri, and the bilateral posterior part of the superior and middle temporal gyri. Stronger activation was found in some of these areas that implicated for remapping tactile stimuli to spatial coordinates after the participants crossed their arms. The activation in the perisylvian areas overlapped with the human visual-motion-sensitive areas in the posterior part. Based on these results, we propose that the temporal order of tactile signals is determined by combining spatial representations of stimuli in the parietal and prefrontal cortices with representations of "motion" or "changes" in the multisensory perisylvian cortex.
Higher Order Residual Analysis for Nonlinear Time Series with Autoregressive Correlation Structures.
1984-09-25
ANALYSIS FOR NONLINEAR TIMEF SERIES WITH AI.OREGRESSIVE CORRELATION STRUVIURES BY P.A.W. Lewis & A. J. Lawrance September 1984 Approved for public release...of all or part of this report is authorized. P.A.W. Lewis A. J. Lawrance Professor of Operations Research University of Birmingham, England ’ Naval...J. Lawrance P. A. W. Lewis 9 PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK AREA G WORK UNIT NUMBERS Naval Postgraduate
Su, Yen-Shuo; Liu, Yu-Hsuan; I, Lin
2012-11-09
Whether the static microstructural order information is strongly correlated with the subsequent structural rearrangement (SR) and their predicting power for SR are investigated experimentally in the quenched dusty plasma liquid with microheterogeneities. The poor local structural order is found to be a good alarm to identify the soft spot and predict the short term SR. For the site with good structural order, the persistent time for sustaining the structural memory until SR has a large mean value but a broad distribution. The deviation of the local structural order from that averaged over nearest neighbors serves as a good second alarm to further sort out the short time SR sites. It has the similar sorting power to that using the temporal fluctuation of the local structural order over a small time interval.
Symmetry and correlations underlying hidden order in URu2Si2
NASA Astrophysics Data System (ADS)
Butch, Nicholas P.; Manley, Michael E.; Jeffries, Jason R.; Janoschek, Marc; Huang, Kevin; Maple, M. Brian; Said, Ayman H.; Leu, Bogdan M.; Lynn, Jeffrey W.
2015-01-01
We experimentally investigate the symmetry in the hidden order (HO) phase of intermetallic URu2Si2 by mapping the lattice and magnetic excitations via inelastic neutron and x-ray scattering measurements in the HO and high-temperature paramagnetic phases. At all temperatures, the excitations respect the zone edges of the body-centered tetragonal paramagnetic phase, showing no signs of reduced spatial symmetry, even in the HO phase. The magnetic excitations originate from transitions between hybridized bands and track the Fermi surface, whose features are corroborated by the phonon measurements. Due to a large hybridization energy scale, a full uranium moment persists in the HO phase, consistent with a lack of observed crystal-field-split states. Our results are inconsistent with local order-parameter models and the behavior of typical density waves. We suggest that an order parameter that does not break spatial symmetry would naturally explain these characteristics.
Abdollah-Nia, Farshad; Gelfand, Martin P; Van Orden, Alan K
2017-02-09
Fluorescence correlation spectroscopy (FCS) is a primary tool in the time-resolved analysis of non-reacting or reacting molecules in solution, based on fluorescence intensity fluctuations. However, conventional FCS alone is insufficient for complete determination of reaction or mixture parameters. In an accompanying article, a technique for computation of artifact-free higher-order correlations with microsecond time resolution was described. Here, we demonstrate applications of the technique to analyze systems of fast and slow reactions. As an example of slow- or non-reacting systems, the technique is applied to resolve two-component mixtures of labeled oligonucleotides. Next, the protonation reaction of fluorescein isothiocyanate (FITC) in phosphate buffer is analyzed as an example of fast reactions (relaxation time <1 μs ). By reference to an (apparent) non-reacting system, the simple factorized form of cumulant-based higher-order correlations is exploited to remove the dependence on the molecular detection function (MDF). Therefore, there is no need to model and characterize the experimental MDF, and the precision and the accuracy of the technique are enhanced. It is verified that higher-order correlation analysis enables complete and simultaneous determination of number and brightness parameters of mixing or reacting molecules, the reaction relaxation time, and forward and reverse reaction rates.
On the structure of Si(100) surface: Importance of higher order correlations for buckled dimer
NASA Astrophysics Data System (ADS)
Back, Seoin; Schmidt, Johan A.; Ji, Hyunjun; Heo, Jiyoung; Shao, Yihan; Jung, Yousung
2013-05-01
We revisit a dangling theoretical question of whether the surface reconstruction of the Si(100) surface would energetically favor the symmetric or buckled dimers on the intrinsic potential energy surfaces at 0 K. This seemingly simple question is still unanswered definitively since all existing density functional based calculations predict the dimers to be buckled, while most wavefunction based correlated treatments prefer the symmetric configurations. Here, we use the doubly hybrid density functional (DHDF) geometry optimizations, in particular, XYGJ-OS, complete active space self-consistent field theory, multi-reference perturbation theory, multi-reference configuration interaction (MRCI), MRCI with the Davidson correction (MRCI + Q), multi-reference average quadratic CC (MRAQCC), and multi-reference average coupled pair functional (MRACPF) methods to address this question. The symmetric dimers are still shown to be lower in energy than the buckled dimers when using the CASPT2 method on the DHDF optimized geometries, consistent with the previous results using B3LYP geometries [Y. Jung, Y. Shao, M. S. Gordon, D. J. Doren, and M. Head-Gordon, J. Chem. Phys. 119, 10917 (2003), 10.1063/1.1620994]. Interestingly, however, the MRCI + Q, MRAQCC, and MRACPF results (which give a more refined description of electron correlation effects) suggest that the buckled dimer is marginally more stable than its symmetric counterpart. The present study underlines the significance of having an accurate description of the electron-electron correlation as well as proper multi-reference wave functions when exploring the extremely delicate potential energy surfaces of the reconstructed Si(100) surface.
Measuring Gaussian Quantum Information and Correlations Using the Rényi Entropy of Order 2
NASA Astrophysics Data System (ADS)
Adesso, Gerardo; Girolami, Davide; Serafini, Alessio
2012-11-01
We demonstrate that the Rényi-2 entropy provides a natural measure of information for any multimode Gaussian state of quantum harmonic systems, operationally linked to the phase-space Shannon sampling entropy of the Wigner distribution of the state. We prove that, in the Gaussian scenario, such an entropy satisfies the strong subadditivity inequality, a key requirement for quantum information theory. This allows us to define and analyze measures of Gaussian entanglement and more general quantum correlations based on such an entropy, which are shown to satisfy relevant properties such as monogamy.
Impact of two-electron dynamics and correlations on high-order-harmonic generation in He
NASA Astrophysics Data System (ADS)
Artemyev, Anton N.; Cederbaum, Lorenz S.; Demekhin, Philipp V.
2017-03-01
The interaction of a helium atom with an intense, short, 800-nm, laser pulse is studied theoretically beyond the single-active-electron approximation. For this purpose, the time-dependent Schrödinger equation for a two-electron wave packet driven by a linearly polarized infrared pulse is solved by the time-dependent restricted-active-space configuration-interaction method in the dipole velocity gauge. By systematically extending the space of active configurations, we investigate the role of the collective two-electron dynamics in the strong-field ionization and high-order-harmonic generation processes. Our numerical results demonstrate that allowing both electrons in He to be dynamically active results in a considerable extension of the computed high-order-harmonic generation spectrum.
The post-mitotic state in neurons correlates with a stable nuclear higher-order structure
Aranda-Anzaldo, Armando
2012-01-01
Neurons become terminally differentiated (TD) post-mitotic cells very early during development yet they may remain alive and functional for decades. TD neurons preserve the molecular machinery necessary for DNA synthesis that may be reactivated by different stimuli but they never complete a successful mitosis. The non-reversible nature of the post-mitotic state in neurons suggests a non-genetic basis for it since no set of mutations has been able to revert it. Comparative studies of the nuclear higher-order structure in neurons and cells with proliferating potential suggest that the non-reversible nature of the post-mitotic state in neurons has a structural basis in the stability of the nuclear higher-order structure. PMID:22808316
Ordered Patterns of Cell Shape and Orientational Correlation during Spontaneous Cell Migration
Iwaya, Suguru; Sano, Masaki
2008-01-01
Background In the absence of stimuli, most motile eukaryotic cells move by spontaneously coordinating cell deformation with cell movement in the absence of stimuli. Yet little is known about how cells change their own shape and how cells coordinate the deformation and movement. Here, we investigated the mechanism of spontaneous cell migration by using computational analyses. Methodology We observed spontaneously migrating Dictyostelium cells in both a vegetative state (round cell shape and slow motion) and starved one (elongated cell shape and fast motion). We then extracted regular patterns of morphological dynamics and the pattern-dependent systematic coordination with filamentous actin (F-actin) and cell movement by statistical dynamic analyses. Conclusions/Significance We found that Dictyostelium cells in both vegetative and starved states commonly organize their own shape into three ordered patterns, elongation, rotation, and oscillation, in the absence of external stimuli. Further, cells inactivated for PI3-kinase (PI3K) and/or PTEN did not show ordered patterns due to the lack of spatial control in pseudopodial formation in both the vegetative and starved states. We also found that spontaneous polarization was achieved in starved cells by asymmetric localization of PTEN and F-actin. This breaking of the symmetry of protein localization maintained the leading edge and considerably enhanced the persistence of directed migration, and overall random exploration was ensured by switching among the different ordered patterns. Our findings suggest that Dictyostelium cells spontaneously create the ordered patterns of cell shape mediated by PI3K/PTEN/F-actin and control the direction of cell movement by coordination with these patterns even in the absence of external stimuli. PMID:19011688
Symmetry and correlations underlying hidden order in URu2Si2
Butch, Nicholas P.; Manley, Michael E.; Jeffries, Jason R.; ...
2015-01-26
In this paper, we experimentally investigate the symmetry in the hidden order (HO) phase of intermetallic URu2Si2 by mapping the lattice and magnetic excitations via inelastic neutron and x-ray scattering measurements in the HO and high-temperature paramagnetic phases. At all temperatures, the excitations respect the zone edges of the body-centered tetragonal paramagnetic phase, showing no signs of reduced spatial symmetry, even in the HO phase. The magnetic excitations originate from transitions between hybridized bands and track the Fermi surface, whose features are corroborated by the phonon measurements. Due to a large hybridization energy scale, a full uranium moment persists inmore » the HO phase, consistent with a lack of observed crystal-field-split states. Our results are inconsistent with local order-parameter models and the behavior of typical density waves. Finally, we suggest that an order parameter that does not break spatial symmetry would naturally explain these characteristics.« less
NASA Technical Reports Server (NTRS)
Kerr, R. A.
1983-01-01
In a three dimensional simulation higher order derivative correlations, including skewness and flatness factors, are calculated for velocity and passive scalar fields and are compared with structures in the flow. The equations are forced to maintain steady state turbulence and collect statistics. It is found that the scalar derivative flatness increases much faster with Reynolds number than the velocity derivative flatness, and the velocity and mixed derivative skewness do not increase with Reynolds number. Separate exponents are found for the various fourth order velocity derivative correlations, with the vorticity flatness exponent the largest. Three dimensional graphics show strong alignment between the vorticity, rate of strain, and scalar-gradient fields. The vorticity is concentrated in tubes with the scalar gradient and the largest principal rate of strain aligned perpendicular to the tubes. Velocity spectra, in Kolmogorov variables, collapse to a single curve and a short minus 5/3 spectral regime is observed.
Azaria, P.; Konik, R. M.; Lecheminant, P.; ...
2016-08-03
In our paper we study a (1+1)-dimensional version of the famous Nambu–Jona-Lasinio model of quantum chromodynamics (QCD2) both at zero and at finite baryon density. We use nonperturbative techniques (non-Abelian bosonization and the truncated conformal spectrum approach). When the baryon chemical potential, μ, is zero, we describe the formation of fermion three-quark (nucleons and Δ baryons) and boson (two-quark mesons, six-quark deuterons) bound states. We also study at μ=0 the formation of a topologically nontrivial phase. When the chemical potential exceeds the critical value and a finite baryon density appears, the model has a rich phase diagram which includes phasesmore » with a density wave and superfluid quasi-long-range (QLR) order, as well as a phase of a baryon Tomonaga-Luttinger liquid (strange metal). Finally, the QLR order results in either a condensation of scalar mesons (the density wave) or six-quark bound states (deuterons).« less
Azaria, P.; Konik, R. M.; Lecheminant, P.; Pálmai, T.; Takács, G.; Tsvelik, A. M.
2016-08-03
In our paper we study a (1+1)-dimensional version of the famous Nambu–Jona-Lasinio model of quantum chromodynamics (QCD2) both at zero and at finite baryon density. We use nonperturbative techniques (non-Abelian bosonization and the truncated conformal spectrum approach). When the baryon chemical potential, μ, is zero, we describe the formation of fermion three-quark (nucleons and Δ baryons) and boson (two-quark mesons, six-quark deuterons) bound states. We also study at μ=0 the formation of a topologically nontrivial phase. When the chemical potential exceeds the critical value and a finite baryon density appears, the model has a rich phase diagram which includes phases with a density wave and superfluid quasi-long-range (QLR) order, as well as a phase of a baryon Tomonaga-Luttinger liquid (strange metal). Finally, the QLR order results in either a condensation of scalar mesons (the density wave) or six-quark bound states (deuterons).
Second-order perturbation theory using correlated orbitals. I. Full-valence reference functions
NASA Astrophysics Data System (ADS)
Parisel, O.; Ellinger, Y.
1994-11-01
Recent developments of performant perturbation treatments on multiconfiguration wave functions have renewed interest in the coupling of variational and perturbative methods. In this communication it is shown that the choice of both the orbitals and the perturbation Hamiltonian to be used is as crucial as the choice of the reference space for obtaining accurate results. Møller-Plesset and Epstein-Nesbet perturbation series are applied to full-valence configuration interaction (FVCI) wave functions built on MCSCF (multi-configurational self-consistent field), FOCI (first-order configuration interaction) and SOCI (second-order configuration interaction) natural orbitals. Applications are presented for the following well-known systems: CH 2 (X 3B 1-a 1A 1), CH 2+ (X 2A 1, 1 2B 1, 1 2A 2, 1 2B 2), SiH 2 (X 1A 1, a 3B 1, A 1B 1) and NH 2 (X 2A 1, A 2B 1). The results are compared to the corresponding full configuration interaction (FCI) when available.
Second-order perturbation theory using correlated orbitals. 1: Full-valence reference functions
NASA Astrophysics Data System (ADS)
Parisel, O.; Ellinger, Y.
1994-11-01
Recent developments of performant perturbation treatments on multiconfiguration wave functions have renewed interest in the coupling of variational and perturbative methods. In this communication it is shown that the choice of both the orbitals and the perturbation Hamiltonian to be used is as crucial as the choice of the reference space for obtaining accurate results. Moller-Plesset and Epstein-Nesbet perturbation series are applied to full-valence configuration interaction (FVCI) wave functions built on MCSCF (multi-configurational self-consistent field), FOCI (first-order configuration interaction) and SOCI (second-order configuration interaction) natural orbitals. Applications are presented for the following well-known systems: CH2(X(sup 3)B(sub 1) -a(sup 1)A(sub 1), CH2(+)(X(sup 2)A(sub 1), 1(sup 2)B(sub 1), 1(sup 2)A(sub 2), 1(sup 2)B(sub 2)), SiH2(X(sub 1)A(sub 1), a(sup 3)B(sub 1), A(sup 1)B(sub 1) and NH2(X(sup 2)A(sub 1), A(sup 2)B(sub 1)). The results are compared to the corresponding full configuration interaction (FCI) when available.
Dissociating the neural correlates of tactile temporal order and simultaneity judgements
Miyazaki, Makoto; Kadota, Hiroshi; Matsuzaki, Kozue S.; Takeuchi, Shigeki; Sekiguchi, Hirofumi; Aoyama, Takuo; Kochiyama, Takanori
2016-01-01
Perceiving temporal relationships between sensory events is a key process for recognising dynamic environments. Temporal order judgement (TOJ) and simultaneity judgement (SJ) are used for probing this perceptual process. TOJ and SJ exhibit identical psychometric parameters. However, there is accumulating psychophysical evidence that distinguishes TOJ from SJ. Some studies have proposed that the perceptual processes for SJ (e.g., detecting successive/simultaneity) are also included in TOJ, whereas TOJ requires more processes (e.g., determination of the temporal order). Other studies have proposed two independent processes for TOJ and SJ. To identify differences in the neural activity associated with TOJ versus SJ, we performed functional magnetic resonance imaging of participants during TOJ and SJ with identical tactile stimuli. TOJ-specific activity was observed in multiple regions (e.g., left ventral and bilateral dorsal premotor cortices and left posterior parietal cortex) that overlap the general temporal prediction network for perception and motor systems. SJ-specific activation was observed only in the posterior insular cortex. Our results suggest that TOJ requires more processes than SJ and that both TOJ and SJ implement specific process components. The neural differences between TOJ and SJ thus combine features described in previous psychophysical hypotheses that proposed different mechanisms. PMID:27064734
Shimazaki, Hideaki; Amari, Shun-ichi; Brown, Emery N.; Grün, Sonja
2012-01-01
Precise spike coordination between the spiking activities of multiple neurons is suggested as an indication of coordinated network activity in active cell assemblies. Spike correlation analysis aims to identify such cooperative network activity by detecting excess spike synchrony in simultaneously recorded multiple neural spike sequences. Cooperative activity is expected to organize dynamically during behavior and cognition; therefore currently available analysis techniques must be extended to enable the estimation of multiple time-varying spike interactions between neurons simultaneously. In particular, new methods must take advantage of the simultaneous observations of multiple neurons by addressing their higher-order dependencies, which cannot be revealed by pairwise analyses alone. In this paper, we develop a method for estimating time-varying spike interactions by means of a state-space analysis. Discretized parallel spike sequences are modeled as multi-variate binary processes using a log-linear model that provides a well-defined measure of higher-order spike correlation in an information geometry framework. We construct a recursive Bayesian filter/smoother for the extraction of spike interaction parameters. This method can simultaneously estimate the dynamic pairwise spike interactions of multiple single neurons, thereby extending the Ising/spin-glass model analysis of multiple neural spike train data to a nonstationary analysis. Furthermore, the method can estimate dynamic higher-order spike interactions. To validate the inclusion of the higher-order terms in the model, we construct an approximation method to assess the goodness-of-fit to spike data. In addition, we formulate a test method for the presence of higher-order spike correlation even in nonstationary spike data, e.g., data from awake behaving animals. The utility of the proposed methods is tested using simulated spike data with known underlying correlation dynamics. Finally, we apply the methods
Olsen, Aaron M
2015-11-01
Herbivory is rare among birds and is usually thought to have evolved predominately among large, flightless birds due to energetic constraints or an association with increased body mass. Nearly all members of the bird order Anseriformes, which includes ducks, geese, and swans, are flighted and many are predominately herbivorous. However, it is unknown whether herbivory represents a derived state for the order and how many times a predominately herbivorous diet may have evolved. Compiling data from over 200 published diet studies to create a continuous character for herbivory, models of trait evolution support at least five independent transitions toward a predominately herbivorous diet in Anseriformes. Although a nonphylogenetic correlation test recovers a significant positive correlation between herbivory and body mass, this correlation is not significant when accounting for phylogeny. These results indicate a lack of support for the hypothesis that a larger body mass confers an advantage in the digestion of low-quality diets but does not exclude the possibility that shifts to a more abundant food source have driven shifts toward herbivory in other bird lineages. The exceptional number of transitions toward a more herbivorous diet in Anseriformes and lack of correlation with body mass prompts a reinterpretation of the relatively infrequent origination of herbivory among flighted birds.
Zhang, Z; Tian, X
2005-01-01
The application of a recently proposed denoising implementation for obtaining cognitive evoked potentials (CEPs) at the single-trial level is shown. The aim of this investigation is to develop the technique of extracting CEPs by combining both the third-order correlation and the wavelet denoising methods. First, the noisy CEPs was passed through a finite impulse response filter whose impulse response is matched with the shape of the noise-free signal. It was shown that it is possible to estimate the filter impulse response on basis of a select third-order correlation slice (TOCS) of the input noisy CEPs. Second, the output from the third-order correlation filter is decomposed with bi-orthogonal splines at 5 levels. The CEPs is reconstructed by wavelet final approximation a
NASA Astrophysics Data System (ADS)
Kumar, Satyendra; Agra-Kooijman, Dena; Acharya, Bharat
2012-02-01
Short-range molecular associations in organic liquids were first described as ``cybotactic'' groups [1] followed by the development of the swarm theory [2] to explain the structure, strong light scattering, and flow behavior of the nematic (N) liquid crystal phase. However, these ideas became inconsequential with the advent of the Oseen-Frank's continuum theory [3]. In 1970, de Vries reinvoked cybotactic groups for the N phase of bis-(4'-n-octyloxybenzal)-2-chloro-l,4-phenylenediamine. These were eventually understood to be SmC pretransitional fluctuations, i.e., small correlated regions of the lower symmetry phase near the transition. Thermotropic biaxial mesophases have resurrected the faith in cybotacticity in the guise of a new word - ``clusters''. Previous x-ray studies of normal organic fluids, and calamitic, lyotropic, and bent-core mesogens show that these clusters fall into three groups depending on the relative contributions of normal liquid structure and pretransitional fluctuations. A comparison with other organic and inorganic fluids will also be made.[4pt] [1] G.W. Stewart, Phys. Rev. 35, 726 (1930).[0pt] [2] L.S. Ornestein and W. Kast, Trans. Farad. Soc. 29, 931 (1933).[0pt] [3] FC Frank, Discuss. Faraday Soc. 25, 19 (1958); W. Oseen, Ark. Mat., Astron. Fys. 19, 1 (1925).
Zhang, Kai; Du, Kai; Liu, Hao; Zhang, X. -G.; Lan, Fanli; Lin, Hanxuan; Wei, Wengang; Zhu, Yinyan; Kou, Yunfang; Shao, Jian; Niu, Jiebin; Wang, Wenbin; Wu, Ruqian; Yin, Lifeng; Plummer, E. W.; Shen, Jian
2015-07-20
The interesting transport and magnetic properties in manganites depend sensitively on the nucleation and growth of electronic phase-separated domains. In this paper, by fabricating antidot arrays in La_{0.325}Pr_{0.3}Ca_{0.375}MnO_{3} (LPCMO) epitaxial thin films, we create ordered arrays of micrometer-sized ferromagnetic metallic (FMM) rings in the LPCMO films that lead to dramatically increased metal–insulator transition temperatures and reduced resistances. The FMM rings emerge from the edges of the antidots where the lattice symmetry is broken. Based on our Monte Carlo simulation, these FMM rings assist the nucleation and growth of FMM phase domains increasing the metal–insulator transition with decreasing temperature or increasing magnetic field. Finally, this study points to a way in which electronic phase separation in manganites can be artificially controlled without changing chemical composition or applying external field.
Zhang, Kai; Du, Kai; Liu, Hao; Zhang, X.-G.; Lan, Fanli; Lin, Hanxuan; Wei, Wengang; Zhu, Yinyan; Kou, Yunfang; Shao, Jian; Niu, Jiebin; Wang, Wenbin; Wu, Ruqian; Yin, Lifeng; Plummer, E. W.; Shen, Jian
2015-01-01
The interesting transport and magnetic properties in manganites depend sensitively on the nucleation and growth of electronic phase-separated domains. By fabricating antidot arrays in La0.325Pr0.3Ca0.375MnO3 (LPCMO) epitaxial thin films, we create ordered arrays of micrometer-sized ferromagnetic metallic (FMM) rings in the LPCMO films that lead to dramatically increased metal–insulator transition temperatures and reduced resistances. The FMM rings emerge from the edges of the antidots where the lattice symmetry is broken. Based on our Monte Carlo simulation, these FMM rings assist the nucleation and growth of FMM phase domains increasing the metal–insulator transition with decreasing temperature or increasing magnetic field. This study points to a way in which electronic phase separation in manganites can be artificially controlled without changing chemical composition or applying external field. PMID:26195791
Approximated optimum condition of second order response surface model with correlated observations
NASA Astrophysics Data System (ADS)
Somayasa, Wayan
2016-06-01
In the present paper we establish an inference procedure for the eigenvalues of the model matrix of the second-order response surface model (RSM). In contrast to the classical treatment where the sample are assumed to be independently distributed, in this work we do not need such distributional simplification. The confidence region for the unknown vector of the eigenvalues is derived by means of delta method. The finite sample behavior of the convergence result is discussed by Monte Carlo Simulation. We get the approximated distribution of the pivotal quantity of the population eigenvalues as a chi-square distribution model. Next we attempt to apply the method to a real data provided by a mining industry. The data represents the percentage of cobalt (Co) observed over the exploration region.
Zhang, Kai; Du, Kai; Liu, Hao; ...
2015-07-20
The interesting transport and magnetic properties in manganites depend sensitively on the nucleation and growth of electronic phase-separated domains. In this paper, by fabricating antidot arrays in La0.325Pr0.3Ca0.375MnO3 (LPCMO) epitaxial thin films, we create ordered arrays of micrometer-sized ferromagnetic metallic (FMM) rings in the LPCMO films that lead to dramatically increased metal–insulator transition temperatures and reduced resistances. The FMM rings emerge from the edges of the antidots where the lattice symmetry is broken. Based on our Monte Carlo simulation, these FMM rings assist the nucleation and growth of FMM phase domains increasing the metal–insulator transition with decreasing temperature or increasingmore » magnetic field. Finally, this study points to a way in which electronic phase separation in manganites can be artificially controlled without changing chemical composition or applying external field.« less
Schmidt, J. A.; Olsen, J. M. H.
2014-11-14
The photodissociation of carbonyl sulfide (OCS) was investigated theoretically in a series of studies by Schmidt and co-workers. Initial studies [J. A. Schmidt, M. S. Johnson, G. C. McBane, and R. Schinke, J. Chem. Phys. 136, 131101 (2012); J. A. Schmidt, M. S. Johnson, G. C. McBane, and R. Schinke, J. Chem. Phys. 137, 054313 (2012)] found photodissociation in the first UV-band to occur mainly by excitation of the 2{sup 1}A{sup ′} (A) excited state. However, in a later study [G. C. McBane, J. A. Schmidt, M. S. Johnson, and R. Schinke, J. Chem. Phys. 138, 094314 (2013)] it was found that a significant fraction of photodissociation must occur by excitation of 1{sup 1}A{sup ″} (B) excited state to explain the product angular distribution. The branching between excitation of the A and B excited states is determined by the magnitude of the transition dipole moment vectors in the Franck-Condon region. This study examines the sensitivity of these quantities to changes in the employed electronic structure methodology. This study benchmarks the methodology employed in previous studies against highly correlated electronic structure methods (CC3 and MRAQCC) and provide evidence in support of the picture of the OCS photodissociation process presented in [G. C. McBane, J. A. Schmidt, M. S. Johnson, and R. Schinke, J. Chem. Phys. 138, 094314 (2013)] showing that excitation of A and B electronic states both contribute significantly to the first UV absorption band of OCS. In addition, this study presents evidence in support of the assertion that the A state potential energy surface employed in previous studies underestimates the energy at highly bent geometries (γ ∼ 70°) leading to overestimated rotational energy in the product CO.
First order phase transformations: scaling relations for grain self-correlation functions
Axe, J.D.; Shapiro, S.M.; Yamada, Y.; Hamaya, N.
1985-06-01
At high pressure many alkali halides transform from the NaCl (B1) structure to the CsCl (B2) structure. We have recently studied this transformation in polycrystalline RbI, which transforms at a critical pressure, P/sub c/ = 3.5 kbar. By observing the time development of the neutron diffraction pattern after sudden increase of hydrostatic pressure from P
P/sub c/ we directly deduced X(t), the fraction of the sample converted from metastable to stable phase, as a function of time. We showed that X(t) taken at different P could be approximately scaled onto a universal growth curve by introducing an adjustable characteristic time tau(P) for each curve. The success of the Kolmogorov in fitting X(t) suggests that comparisons of model predictions with other experimental observables be made on the system. For example, by a trivial (in principle) extension of the neutron diffraction techniques described above, one might determine the broadening of the powder diffraction peaks due to finite grain size as a function of time throughout growth. This particle size broadening is related by Fourier transformation to the grain autocorrelation function, G/sub s/(r,t), which measures the ensemble average of the overlap of grains with themselves upon translation of the grain pattern by an amount r. We present some results of a study of the scaling properties of G/sub s/(r,t) for the Kolmogorov model for d=1 and d=2. Although the model is highly idealized, it is perhaps the simplest conceivable one which obeys correlation function scaling in early stages of growth and undergoes nontrivial saturation due to volume fraction effects in the late stages. 4 refs., 6 figs.
Liu, Qing; Shi, Chaowei; Yu, Lu; Zhang, Longhua; Xiong, Ying; Tian, Changlin
2015-02-13
Internal backbone dynamic motions are essential for different protein functions and occur on a wide range of time scales, from femtoseconds to seconds. Molecular dynamic (MD) simulations and nuclear magnetic resonance (NMR) spin relaxation measurements are valuable tools to gain access to fast (nanosecond) internal motions. However, there exist few reports on correlation analysis between MD and NMR relaxation data. Here, backbone relaxation measurements of (15)N-labeled SH3 (Src homology 3) domain proteins in aqueous buffer were used to generate general order parameters (S(2)) using a model-free approach. Simultaneously, 80 ns MD simulations of SH3 domain proteins in a defined hydrated box at neutral pH were conducted and the general order parameters (S(2)) were derived from the MD trajectory. Correlation analysis using the Gromos force field indicated that S(2) values from NMR relaxation measurements and MD simulations were significantly different. MD simulations were performed on models with different charge states for three histidine residues, and with different water models, which were SPC (simple point charge) water model and SPC/E (extended simple point charge) water model. S(2) parameters from MD simulations with charges for all three histidines and with the SPC/E water model correlated well with S(2) calculated from the experimental NMR relaxation measurements, in a site-specific manner.
NASA Astrophysics Data System (ADS)
Wierschem, K.; Beach, K. S. D.
2016-06-01
The strange correlator [Phys. Rev. Lett. 112, 247202 (2014), 10.1103/PhysRevLett.112.247202] has been proposed as a measure of symmetry protected topological order in one- and two-dimensional systems. It takes the form of a spin-spin correlation function, computed as a mixed overlap between the state of interest and a trivial local product state. We demonstrate that it can be computed exactly (asymptotically, in the Monte Carlo sense) for various Affleck-Kennedy-Lieb-Tasaki states by direct evaluation of the wave function within the valence bond loop gas framework. We present results for lattices with chain, square, honeycomb, cube, diamond, and hyperhoneycomb geometries. In each case, the spin quantum number S is varied such that 2 S (the number of valence bonds emerging from each site) achieves various integer multiples of the lattice coordination number. We introduce the concept of strange correlator loop winding number and point to its utility in testing for the presence of symmetry protected topological order.
Persi, Erez; Horn, David
2013-01-01
We present a novel analysis of compositional order (CO) based on the occurrence of Frequent amino-acid Triplets (FTs) that appear much more than random in protein sequences. The method captures all types of proteomic compositional order including single amino-acid runs, tandem repeats, periodic structure of motifs and otherwise low complexity amino-acid regions. We introduce new order measures, distinguishing between ‘regularity’, ‘periodicity’ and ‘vocabulary’, to quantify these phenomena and to facilitate the identification of evolutionary effects. Detailed analysis of representative species across the tree-of-life demonstrates that CO proteins exhibit numerous functional enrichments, including a wide repertoire of particular patterns of dependencies on regularity and periodicity. Comparison between human and mouse proteomes further reveals the interplay of CO with evolutionary trends, such as faster substitution rate in mouse leading to decrease of periodicity, while innovation along the human lineage leads to larger regularity. Large-scale analysis of 94 proteomes leads to systematic ordering of all major taxonomic groups according to FT-vocabulary size. This is measured by the count of Different Frequent Triplets (DFT) in proteomes. The latter provides a clear hierarchical delineation of vertebrates, invertebrates, plants, fungi and prokaryotes, with thermophiles showing the lowest level of FT-vocabulary. Among eukaryotes, this ordering correlates with phylogenetic proximity. Interestingly, in all kingdoms CO accumulation in the proteome has universal characteristics. We suggest that CO is a genomic-information correlate of both macroevolution and various protein functions. The results indicate a mechanism of genomic ‘innovation’ at the peptide level, involved in protein elongation, shaped in a universal manner by mutational and selective forces. PMID:24278003
Lee, Lloyd L
2013-10-21
We develop the potential distributions of several test particles to obtain a hierarchy of the nonuniform singlet direct correlation functions (s-DCFs). These correlation functions are interpreted as the segmental chemical potentials or works of insertion of successive test particles in a classical fluid. The development has several interesting consequences: (i) it extends the Widom particle insertion formula to higher-order theorems, the first member gives the chemical potential as in the original theorem, the second member gives the incremental energy for dimer formation, with higher members giving the energies for forming trimers, tetramers, etc. (ii) The second and third order s-DCFs can be related to the cavity distribution functions y((2)) and y((3)) in the liquid-state theory. Thus we can express the triplet cavity function y((3)) in terms of these s-DCFs in an exact form. This enables us to calculate, as an illustration of the above theoretical developments, the numerical values of the s-DCFs via Monte Carlo (MC) simulation data on hard spheres. We use these data to critically analyze the commonly used approximations, the Kirkwood superposition (KSA) and the linear approximation (LA) for triplet correlation functions. An improved rule over KSA and LA is proposed for triplet hard spheres in the rolling-contact configurations. (iii) The s-DCFs are naturally suited for analyzing the chain-incremental Ansatz or hypothesis in the calculation of the chemical potentials of polymeric chain molecules. The first few segments of a polymer chain have been shown from extensive Monte Carlo simulations to not obey this Ansatz. By examining the insertion energies of successive segments through the s-DCFs, we are able to quantitatively decipher the decay of the segmental chemical potentials for at least the first three segments. Comparison with MC data on 4-mer and 8-mer hard-sphere fluids shows commensurate behavior with the s-DCFs. In addition, an analytical density
Zhou Yu; Simon, Jason; Liu Jianbin; Shih, Yanhua
2010-04-15
In a near-field three-photon correlation measurement, we observed the third-order temporal and spatial correlation functions of chaotic thermal light in the single-photon counting regime. In the study, we found that the probability of jointly detecting three randomly radiated photons from a chaotic thermal source by three individual detectors is 6 times greater if the photodetection events fall in the coherence time and coherence area of the radiation field than if they do not. From the viewpoint of quantum mechanics, the observed phenomenon is the result of three-photon interference. By making use of this property, we measured the three-photon thermal light lensless ghost image of a double spot and achieved higher visibility compared with the two-photon thermal light ghost image.
Mangum, Benjamin D.; Ghosh, Yagnaseni; Hollingsworth, Jennifer A.; Htoon, Han
2013-01-01
In single particle spectroscopy, the degree of observed fluorescence anti-bunching in a second-order cross correlation experiment is indicative of its bi-exciton quantum yield and whether or not a particle is well isolated. Advances in quantum dot synthesis have produced single particles with bi-exciton quantum yields approaching unity. Consequently, this creates uncertainty as to whether a particle has a high bi-exciton quantum yield or if it exists as a cluster. We report on a time-gated anti-bunching technique capable of determining the relative contributions of both multi-exciton emission and clustering effects. In this way, we can now unambiguously determine if a particle is single. Additionally, this time-gated anti-bunching approach provides an accurate way for the determination of bi-exciton lifetime with minimal contribution from higher order multi-exciton states. PMID:23546125
Shang, Yu; Yu, Guoqiang
2014-09-29
Conventional semi-infinite analytical solutions of correlation diffusion equation may lead to errors when calculating blood flow index (BFI) from diffuse correlation spectroscopy (DCS) measurements in tissues with irregular geometries. Very recently, we created an algorithm integrating a Nth-order linear model of autocorrelation function with the Monte Carlo simulation of photon migrations in homogenous tissues with arbitrary geometries for extraction of BFI (i.e., αDB ). The purpose of this study is to extend the capability of the Nth-order linear algorithm for extracting BFI in heterogeneous tissues with arbitrary geometries. The previous linear algorithm was modified to extract BFIs in different types of tissues simultaneously through utilizing DCS data at multiple source-detector separations. We compared the proposed linear algorithm with the semi-infinite homogenous solution in a computer model of adult head with heterogeneous tissue layers of scalp, skull, cerebrospinal fluid, and brain. To test the capability of the linear algorithm for extracting relative changes of cerebral blood flow (rCBF) in deep brain, we assigned ten levels of αDB in the brain layer with a step decrement of 10% while maintaining αDB values constant in other layers. Simulation results demonstrate the accuracy (errors < 3%) of high-order (N ≥ 5) linear algorithm in extracting BFIs in different tissue layers and rCBF in deep brain. By contrast, the semi-infinite homogenous solution resulted in substantial errors in rCBF (34.5% ≤ errors ≤ 60.2%) and BFIs in different layers. The Nth-order linear model simplifies data analysis, thus allowing for online data processing and displaying. Future study will test this linear algorithm in heterogeneous tissues with different levels of blood flow variations and noises.
Shang, Yu; Yu, Guoqiang
2014-09-29
Conventional semi-infinite analytical solutions of correlation diffusion equation may lead to errors when calculating blood flow index (BFI) from diffuse correlation spectroscopy (DCS) measurements in tissues with irregular geometries. Very recently, we created an algorithm integrating a Nth-order linear model of autocorrelation function with the Monte Carlo simulation of photon migrations in homogenous tissues with arbitrary geometries for extraction of BFI (i.e., αD{sub B}). The purpose of this study is to extend the capability of the Nth-order linear algorithm for extracting BFI in heterogeneous tissues with arbitrary geometries. The previous linear algorithm was modified to extract BFIs in different types of tissues simultaneously through utilizing DCS data at multiple source-detector separations. We compared the proposed linear algorithm with the semi-infinite homogenous solution in a computer model of adult head with heterogeneous tissue layers of scalp, skull, cerebrospinal fluid, and brain. To test the capability of the linear algorithm for extracting relative changes of cerebral blood flow (rCBF) in deep brain, we assigned ten levels of αD{sub B} in the brain layer with a step decrement of 10% while maintaining αD{sub B} values constant in other layers. Simulation results demonstrate the accuracy (errors < 3%) of high-order (N ≥ 5) linear algorithm in extracting BFIs in different tissue layers and rCBF in deep brain. By contrast, the semi-infinite homogenous solution resulted in substantial errors in rCBF (34.5% ≤ errors ≤ 60.2%) and BFIs in different layers. The Nth-order linear model simplifies data analysis, thus allowing for online data processing and displaying. Future study will test this linear algorithm in heterogeneous tissues with different levels of blood flow variations and noises.
Feng, Yu; Tran, Karen; Bale, Shridhar; Kumar, Shailendra; Guenaga, Javier; Wilson, Richard; de Val, Natalia; Arendt, Heather; DeStefano, Joanne; Ward, Andrew B; Wyatt, Richard T
2016-08-01
In the context of HIV vaccine design and development, HIV-1 spike mimetics displaying a range of stabilities were evaluated to determine whether more stable, well-ordered trimers would more efficiently elicit neutralizing antibodies. To begin, in vitro analysis of trimers derived from the cysteine-stabilized SOSIP platform or the uncleaved, covalently linked NFL platform were evaluated. These native-like trimers, derived from HIV subtypes A, B, and C, displayed a range of thermostabilities, and were "stress-tested" at varying temperatures as a prelude to in vivo immunogenicity. Analysis was performed both in the absence and in the presence of two different adjuvants. Since partial trimer degradation was detected at 37°C before or after formulation with adjuvant, we sought to remedy such an undesirable outcome. Cross-linking (fixing) of the well-ordered trimers with glutaraldehyde increased overall thermostability, maintenance of well-ordered trimer integrity without or with adjuvant, and increased resistance to solid phase-associated trimer unfolding. Immunization of unfixed and fixed well-ordered trimers into animals revealed that the elicited tier 2 autologous neutralizing activity correlated with overall trimer thermostability, or melting temperature (Tm). Glutaraldehyde fixation also led to higher tier 2 autologous neutralization titers. These results link retention of trimer quaternary packing with elicitation of tier 2 autologous neutralizing activity, providing important insights for HIV-1 vaccine design.
NASA Astrophysics Data System (ADS)
Van Hung, Nguyen; Hue, Trinh Thi; Khoa, Ha Dang; Vuong, Dinh Quoc
2016-12-01
High-order expanded interatomic effective potential and Debye-Waller factors (DWFs) for local vibrational amplitudes in X-ray absorption fine structure (XAFS) of bcc crystals have been studied based on the anharmonic correlated Debye model. DWFs are presented in terms of cumulant expansion up to the fourth order and the many-body effects are taken into account in the present one-dimensional model based on the first shell near neighbor contribution approach used in the derivations of the anharmonic effective potential and XAFS cumulants where Morse potential is assumed to describe the single-pair atomic interaction. Analytical expressions for the dispersion relation, correlated Debye frequency and temperature and four first temperature-dependent XAFS cumulants have been derived based on the many-body perturbation approach. Thermodynamic properties and anharmonic effects in XAFS of bcc crystals described by the obtained cumulants have been in detail discussed. The advantage and efficiency of the present theory are illustrated by good agreement of the numerical results for Mo, Fe and W with experiment.
NASA Astrophysics Data System (ADS)
Grabowski, Ireneusz; Fabiano, Eduardo; Teale, Andrew M.; Śmiga, Szymon; Buksztel, Adam; Della Sala, Fabio
2014-07-01
The performance of correlated optimized effective potential (OEP) functionals based on the spin-resolved second-order correlation energy is analysed. The relative importance of singly- and doubly- excited contributions as well as the effect of scaling the same- and opposite- spin components is investigated in detail comparing OEP results with Kohn-Sham (KS) quantities determined via an inversion procedure using accurate ab initio electronic densities. Special attention is dedicated in particular to the recently proposed scaled-opposite-spin OEP functional [I. Grabowski, E. Fabiano, and F. Della Sala, Phys. Rev. B 87, 075103 (2013)] which is the most advantageous from a computational point of view. We find that for high accuracy, a careful, system dependent, selection of the scaling coefficient is required. We analyse several size-extensive approaches for this selection. Finally, we find that a composite approach, named OEP2-SOSh, based on a post-SCF rescaling of the correlation energy can yield high accuracy for many properties, being comparable with the most accurate OEP procedures previously reported in the literature but at substantially reduced computational effort.
Grabowski, Ireneusz; Fabiano, Eduardo; Teale, Andrew M; Śmiga, Szymon; Buksztel, Adam; Della Sala, Fabio
2014-07-14
The performance of correlated optimized effective potential (OEP) functionals based on the spin-resolved second-order correlation energy is analysed. The relative importance of singly- and doubly- excited contributions as well as the effect of scaling the same- and opposite- spin components is investigated in detail comparing OEP results with Kohn-Sham (KS) quantities determined via an inversion procedure using accurate ab initio electronic densities. Special attention is dedicated in particular to the recently proposed scaled-opposite-spin OEP functional [I. Grabowski, E. Fabiano, and F. Della Sala, Phys. Rev. B 87, 075103 (2013)] which is the most advantageous from a computational point of view. We find that for high accuracy, a careful, system dependent, selection of the scaling coefficient is required. We analyse several size-extensive approaches for this selection. Finally, we find that a composite approach, named OEP2-SOSh, based on a post-SCF rescaling of the correlation energy can yield high accuracy for many properties, being comparable with the most accurate OEP procedures previously reported in the literature but at substantially reduced computational effort.
Hättig, Christof; Tew, David P; Helmich, Benjamin
2012-05-28
We present an algorithm for computing explicitly correlated second- and third-order Møller-Plesset energies near the basis set limit for large molecules with a cost that scales formally as N(4) with system size N. This is achieved through a hybrid approach where locality is exploited first through orbital specific virtuals (OSVs) and subsequently through pair natural orbitals (PNOs) and integrals are approximated using density fitting. Our method combines the low orbital transformation costs of the OSVs with the compactness of the PNO representation of the doubles amplitude vector. The N(4) scaling does not rely upon the a priori definition of domains, enforced truncation of pair lists, or even screening and the energies converge smoothly to the canonical values with decreasing occupation number thresholds, used in the selection of the PNO basis. For MP2.5 intermolecular interaction energies, we find that 99% of benchmark basis set limit correlation energy contributions are recovered using an aug-cc-pVTZ basis and that on average only 50 PNOs are required to correlate the significant orbital pairs.
NASA Astrophysics Data System (ADS)
Hättig, Christof; Tew, David P.; Helmich, Benjamin
2012-05-01
We present an algorithm for computing explicitly correlated second- and third-order Møller-Plesset energies near the basis set limit for large molecules with a cost that scales formally as N^4 with system size N. This is achieved through a hybrid approach where locality is exploited first through orbital specific virtuals (OSVs) and subsequently through pair natural orbitals (PNOs) and integrals are approximated using density fitting. Our method combines the low orbital transformation costs of the OSVs with the compactness of the PNO representation of the doubles amplitude vector. The N^4 scaling does not rely upon the a priori definition of domains, enforced truncation of pair lists, or even screening and the energies converge smoothly to the canonical values with decreasing occupation number thresholds, used in the selection of the PNO basis. For MP2.5 intermolecular interaction energies, we find that 99% of benchmark basis set limit correlation energy contributions are recovered using an aug-cc-pVTZ basis and that on average only 50 PNOs are required to correlate the significant orbital pairs.
Grabowski, Ireneusz Śmiga, Szymon; Buksztel, Adam; Fabiano, Eduardo; Teale, Andrew M.; Sala, Fabio Della
2014-07-14
The performance of correlated optimized effective potential (OEP) functionals based on the spin-resolved second-order correlation energy is analysed. The relative importance of singly- and doubly- excited contributions as well as the effect of scaling the same- and opposite- spin components is investigated in detail comparing OEP results with Kohn–Sham (KS) quantities determined via an inversion procedure using accurate ab initio electronic densities. Special attention is dedicated in particular to the recently proposed scaled-opposite–spin OEP functional [I. Grabowski, E. Fabiano, and F. Della Sala, Phys. Rev. B 87, 075103 (2013)] which is the most advantageous from a computational point of view. We find that for high accuracy, a careful, system dependent, selection of the scaling coefficient is required. We analyse several size-extensive approaches for this selection. Finally, we find that a composite approach, named OEP2-SOSh, based on a post-SCF rescaling of the correlation energy can yield high accuracy for many properties, being comparable with the most accurate OEP procedures previously reported in the literature but at substantially reduced computational effort.
NASA Astrophysics Data System (ADS)
Bai, Ruixiang; Jiang, Hao; Lei, Zhenkun; Li, Weikang
2017-03-01
Compared with the traditional forward compositional matching strategy, the inverse compositional matching strategy has almost the same accuracy, but has an obviously higher efficiency than the former in digital image correlation (DIC) algorithms. Based on the inverse compositional matching strategy and the auxiliary displacement functions, a more accurate inverse compositional Gauss-Newton (IC-GN2) algorithm with a new second-order shape operator is proposed for nonuniform and large deformation measurements. A theoretical deduction showed that the new proposed second-order shape operator is invertible and can steadily attain second-order precision. The result of the numerical simulation showed that the matching accuracy of the new IC-GN2 algorithm is the same as that of the forward compositional Gauss-Newton (FC-GN2) algorithm and is relatively better than in IC-GN2 algorithm. Finally, a rubber tension experiment with a large deformation of 27% was performed to validate the feasibility of the proposed algorithm.
Finley, Anna J.; Tang, David; Schmeichel, Brandon J.
2015-01-01
Prior research has found that persons who favor more analytic modes of thought are less religious. We propose that individual differences in analytic thought are associated with reduced religious beliefs particularly when analytic thought is measured (hence, primed) first. The current study provides a direct replication of prior evidence that individual differences in analytic thinking are negatively related to religious beliefs when analytic thought is measured before religious beliefs. When religious belief is measured before analytic thinking, however, the negative relationship is reduced to non-significance, suggesting that the link between analytic thought and religious belief is more tenuous than previously reported. The current study suggests that whereas inducing analytic processing may reduce religious belief, more analytic thinkers are not necessarily less religious. The potential for measurement order to inflate the inverse correlation between analytic thinking and religious beliefs deserves additional consideration. PMID:26402334
Finley, Anna J; Tang, David; Schmeichel, Brandon J
2015-01-01
Prior research has found that persons who favor more analytic modes of thought are less religious. We propose that individual differences in analytic thought are associated with reduced religious beliefs particularly when analytic thought is measured (hence, primed) first. The current study provides a direct replication of prior evidence that individual differences in analytic thinking are negatively related to religious beliefs when analytic thought is measured before religious beliefs. When religious belief is measured before analytic thinking, however, the negative relationship is reduced to non-significance, suggesting that the link between analytic thought and religious belief is more tenuous than previously reported. The current study suggests that whereas inducing analytic processing may reduce religious belief, more analytic thinkers are not necessarily less religious. The potential for measurement order to inflate the inverse correlation between analytic thinking and religious beliefs deserves additional consideration.
NASA Astrophysics Data System (ADS)
Ruta, Sergiu; Hovorka, Ondrej; Huang, Pin-Wei; Wang, Kangkang; Ju, Ganping; Chantrell, Roy
2017-03-01
The generic problem of extracting information on intrinsic particle properties from the whole class of interacting magnetic fine particle systems is a long standing and difficult inverse problem. As an example, the Switching Field Distribution (SFD) is an important quantity in the characterization of magnetic systems, and its determination in many technological applications, such as recording media, is especially challenging. Techniques such as the first order reversal curve (FORC) methods, were developed to extract the SFD from macroscopic measurements. However, all methods rely on separating the contributions to the measurements of the intrinsic SFD and the extrinsic effects of magnetostatic and exchange interactions. We investigate the underlying physics of the FORC method by applying it to the output predictions of a kinetic Monte-Carlo model with known input parameters. We show that the FORC method is valid only in cases of weak spatial correlation of the magnetisation and suggest a more general approach.
NASA Astrophysics Data System (ADS)
DeVane, Russell; Ridley, Christina; Space, Brian; Keyes, T.
2005-11-01
Multidimensional spectroscopy has the ability to provide great insight into the complex dynamics and time-resolved structure of liquids. Theoretically describing these experiments requires calculating the nonlinear-response function, which is a combination of quantum-mechanical time correlation functions (TCFs), making it extremely difficult to calculate. Recently, a new theory was presented in which the two-dimensional Raman quantum response function R(5)(t1,t2) was expressed with a two-time, computationally tractable, classical TCF. Writing the response function in terms of classical TCFs brings the full power of atomistically detailed molecular dynamics to the problem. In this paper, the new TCF theory is employed to calculate the fifth-order Raman response function for liquid xenon and investigate several of the polarization conditions for which experiments can be performed on an isotropic system. The theory is shown to reproduce line-shape characteristics predicted by earlier theoretical work.
Ruta, Sergiu; Hovorka, Ondrej; Huang, Pin-Wei; Wang, Kangkang; Ju, Ganping; Chantrell, Roy
2017-01-01
The generic problem of extracting information on intrinsic particle properties from the whole class of interacting magnetic fine particle systems is a long standing and difficult inverse problem. As an example, the Switching Field Distribution (SFD) is an important quantity in the characterization of magnetic systems, and its determination in many technological applications, such as recording media, is especially challenging. Techniques such as the first order reversal curve (FORC) methods, were developed to extract the SFD from macroscopic measurements. However, all methods rely on separating the contributions to the measurements of the intrinsic SFD and the extrinsic effects of magnetostatic and exchange interactions. We investigate the underlying physics of the FORC method by applying it to the output predictions of a kinetic Monte-Carlo model with known input parameters. We show that the FORC method is valid only in cases of weak spatial correlation of the magnetisation and suggest a more general approach. PMID:28338056
NASA Astrophysics Data System (ADS)
Bogdanov, Yu. I.; Katamadze, K. G.; Avosopyants, G. V.; Belinsky, L. V.; Bogdanova, N. A.; Kulik, S. P.; Lukichev, V. F.
2016-12-01
The estimation of high order correlation function values is an important problem in the field of quantum computation. We show that the problem can be reduced to preparation and measurement of optical quantum states resulting after annihilation of a set number of quanta from the original beam. We apply this approach to explore various photon bunching regimes in optical states with gamma-compounded Poisson photon number statistics. We prepare and perform measurement of the thermal quantum state as well as states produced by subtracting one to ten photons from it. Maximum likelihood estimation is employed for parameter estimation. The goal of this research is the development of highly accurate procedures for generation and quality control of optical quantum states.
Queirós, António; Villa-Collar, César; Jorge, Jorge; Gutiérrez, Ángel Ramón; González-Méijome, José Manuel
2012-01-01
Background To analyse the asphericity of the anterior corneal surface (ACS) for different diameters, and correlate those values with corneal higher order aberrations (cHOA) before and after myopic treatments with corneal refractive therapy (CRT) for orthokeratology and customized (CL) and standard laser (SL) assisted in situ keratomileusis (LASIK). Setting Clínica Oftalmológica NovoVisión, Madrid, Spain. Methods The right eyes of 81 patients (27 in each treatment group), with a mean age of 29.94 ± 7.5 years, were analysed. Corneal videokeratographic data were used to obtain corneal asphericity (Q) for different corneal diameters from 3 to 8 mm and cHOA root mean square (RMS) obtained from Zernike polynomials for a pupil diameter of 6 mm. Results There were statistically significant differences in asphericity values calculated at different corneal diameters for different refractive treatments and their changes. The difference between asphericity at 3 and 8 mm reference diameters showed statistically significant correlations with spherical-like cHOA that was also significantly increased after all procedures. Conclusions The shift in corneal asphericity and the differences among different treatment techniques are more evident for the smaller reference diameters. These differences can be much reduced or even masked for a peripheral reference point at 4 mm from centre, which is used by some corneal topographers.
Yu, Sung-Nien; Liu, Fan-Tsen
2014-01-01
Regular electrocardiogram beat classification system usually based on single lead ECG signal. This study designated to add a second lead of ECG signal to the system and apply higher-order statistics and inter-lead cross-correlation features to study the influence of the second lead to the recognition rates and noise-tolerance of the classifier. Discrete wavelet transformation is employed to decompose the ECG signals into different subband components and higher order statistics is recruited to characterize the ECG signals as an attempt to elevate the accuracy and noise-resistibility of heartbeat discrimination. A feed-forward back-propagation neural network (FFBNN) is employed as classifier. When compared with the system that uses only one lead, the second lead raises the recognition rate from 97.74% to 98.25%. We also study the ability of the two-lead system in resisting different levels of white Gaussian noise. More than 97.8% accuracy can be retained with the two-lead system even when the SNR decreases to 10 dB.
NASA Astrophysics Data System (ADS)
Vilardy, Juan M.; Millán, María S.; Pérez-Cabré, Elisabet
2017-02-01
A novel nonlinear image encryption scheme based on a fully phase nonzero-order joint transform correlator architecture (JTC) in the Gyrator domain (GD) is proposed. In this encryption scheme, the two non-overlapping data distributions of the input plane of the JTC are fully encoded in phase and this input plane is transformed using the Gyrator transform (GT); the intensity distribution captured in the GD represents a new definition of the joint Gyrator power distribution (JGPD). The JGPD is modified by two nonlinear operations with the purpose of retrieving the encrypted image, with enhancement of the decrypted signal quality and improvement of the overall security. There are three keys used in the encryption scheme, two random phase masks and the rotation angle of the GT, which are all necessary for a proper decryption. Decryption is highly sensitivity to changes of the rotation angle of the GT as well as to little changes in other parameters or keys. The proposed encryption scheme in the GD still preserves the shift-invariance properties originated in the JTC-based encryption in the Fourier domain. The proposed encryption scheme is more resistant to brute force attacks, chosen-plaintext attacks, known-plaintext attacks, and ciphertext-only attacks, as they have been introduced in the cryptanalysis of the JTC-based encryption system. Numerical results are presented and discussed in order to verify and analyze the feasibility and validity of the novel encryption-decryption scheme.
Shang, Yu; Lin, Yu; Yu, Guoqiang; Li, Ting; Chen, Lei; Toborek, Michal
2014-05-12
Conventional semi-infinite solution for extracting blood flow index (BFI) from diffuse correlation spectroscopy (DCS) measurements may cause errors in estimation of BFI (αD{sub B}) in tissues with small volume and large curvature. We proposed an algorithm integrating Nth-order linear model of autocorrelation function with the Monte Carlo simulation of photon migrations in tissue for the extraction of αD{sub B}. The volume and geometry of the measured tissue were incorporated in the Monte Carlo simulation, which overcome the semi-infinite restrictions. The algorithm was tested using computer simulations on four tissue models with varied volumes/geometries and applied on an in vivo stroke model of mouse. Computer simulations shows that the high-order (N ≥ 5) linear algorithm was more accurate in extracting αD{sub B} (errors < ±2%) from the noise-free DCS data than the semi-infinite solution (errors: −5.3% to −18.0%) for different tissue models. Although adding random noises to DCS data resulted in αD{sub B} variations, the mean values of errors in extracting αD{sub B} were similar to those reconstructed from the noise-free DCS data. In addition, the errors in extracting the relative changes of αD{sub B} using both linear algorithm and semi-infinite solution were fairly small (errors < ±2.0%) and did not rely on the tissue volume/geometry. The experimental results from the in vivo stroke mice agreed with those in simulations, demonstrating the robustness of the linear algorithm. DCS with the high-order linear algorithm shows the potential for the inter-subject comparison and longitudinal monitoring of absolute BFI in a variety of tissues/organs with different volumes/geometries.
NASA Astrophysics Data System (ADS)
Bennett, Edmund; Mydosh, J. A.
2012-09-01
We summarize the development of strongly correlated electron physics (SCEP) stimu-lated from the 1930's when a strange upturn was found in the electrical resistivity at low temper-atures. It was only in 1965 that this effect was explained as a many-body, spin-flip, scattering of electrons from a magnetic impurity, i.e., the Kondo effect. This marked the beginning of SCEP. When the concentration of these impurities is increased so that they can randomly interact we have the spin glasses and their unconventional, yet classical phase transition. Spin glass physics formed the background know-how for the combination of two ferromagnetic layers separated by a non-magnetic spacer which generated the the giant magnetic resistance and it many applications in com-puter hardware. By fabricating a lattice of the magnetic species, viz., an intermetallic compound based upon certain rare-earth and actinide elements, we then create a heavy Fermi liquid that can support most unusual ground-state behavior, e.g., unconventional superconductivity. This leads to the mysterious and still unexplained "hidden order" phase transition of URu2Si2. Finally, since the heavy fermions commonly exhibit zero temperature phase transitions, aka, quantum phase transitions when tuned with pressure, magnetic field or doping, we are at the summit of today's SCEP - the prime topic of 2012 condensed matter physics.
NASA Technical Reports Server (NTRS)
Moore, Craig E.; Cardelino, Beatriz H.; Frazier, Donald O.; Niles, Julian; Wang, Xian-Qiang
1997-01-01
Calculations were performed on the valence contribution to the static molecular third-order polarizabilities (gamma) of thirty carbon-cage fullerenes (C60, C70, five isomers of C78, and twenty-three isomers of C84). The molecular structures were obtained from B3LYP/STO-3G calculations. The values of the tensor elements and an associated numerical uncertainty were obtained using the finite-field approach and polynomial expansions of orders four to eighteen of polarization versus static electric field data. The latter information was obtained from semiempirical calculations using the AM1 hamiltonian.
Migliorati, Valentina; Serva, Alessandra; Aquilanti, Giuliana; Pascarelli, Sakura; D'Angelo, Paola
2015-07-07
A thorough characterization of the structural properties of alkylimidazolium halide ionic liquids (ILs), namely 1-alkyl-3-methylimidazolium bromide ([Cnmim]Br with n = 5, 6, 8, 10) and iodide ([C6mim]I), has been carried out by combining molecular dynamics simulations and EXAFS spectroscopy. The existence of a local order in [Cnmim]Br ILs has been evidenced, with anions and imidazolium head groups forming a local three-dimensional bonding pattern that is common to all the [Cnmim]Br IL family, regardless of the length of the alkyl chain attached to the cation. On the other hand, upon alkyl chain elongation significant differences have been highlighted in the long-range structure of these ILs. Theoretical X-ray structure factors have been calculated from MD simulations and a low q peak has been found for all [Cnmim]Br ILs, indicating the existence of long-range structural correlations. The low q peak moves to smaller q values corresponding to longer distances, increases in intensity and sharpens with increasing alkyl chain length on the cation. Similarities and differences between the ion three-dimensional arrangements in [C6mim]Br and [C6mim]I were highlighted and the structural arrangement of Br(-) and I(-) was found to be different in the proximity of the most acidic hydrogen atom of the imidazolium ring: the I(-) ion is preferentially located above and below the ring plane, while the Br(-) ion has a high probability also to be coplanar with the imidazolium ring. A quantitative analysis of the Br and I K-edge EXAFS spectra of alkylimidazolium halide ILs has been carried out based on the microscopic description of the systems derived from MD simulations. A very good agreement between theoretical and experimental EXAFS signals has been obtained, allowing us to assess the reliability of the MD structural results for all the alkylimidazolium halide ILs investigated in this work.
Abdollah-Nia, Farshad; Gelfand, Martin P; Van Orden, Alan
2017-03-10
Fluorescence correlation spectroscopy (FCS) is a powerful tool in the time-resolved analysis of nonreacting or reacting molecules in solution, based on fluorescence intensity fluctuations. However, conventional (second-order) FCS alone is insufficient to measure all parameters needed to describe a reaction or mixture, including concentrations, fluorescence brightnesses, and forward and reverse rate constants. For this purpose, correlations of higher powers of fluorescence intensity fluctuations can be calculated to yield additional information from the single-photon data stream collected in an FCS experiment. To describe systems of diffusing and reacting molecules, considering cumulants of fluorescence intensity results in simple expressions in which the reaction and diffusion parts factorize. The computation of higher-order correlations in experiments is hindered by shot-noise and common detector artifacts, the effects of which become worse with increasing order. In this article, we introduce a technique to calculate artifact-free higher-order correlation functions with improved time resolution, and without any need for modeling and calibration of detector artifacts. The technique is formulated for general multidetector experiments and verified in both two-detector and single-detector configurations. Good signal-to-noise ratio is achieved down to 1 μs in correlation curves up to order (2, 2). This capability makes possible a variety of new measurements including multicomponent analysis and fast reaction kinetics, as demonstrated in a companion article (10.1021/acs.jpcb.7b00408).
Hill, J Grant
2011-07-28
Auxiliary basis sets specifically matched to the correlation consistent cc-pVnZ-PP, cc-pwCVnZ-PP, aug-cc-pVnZ-PP, and aug-cc-pwCVnZ-PP orbital basis sets (used in conjunction with pseudopotentials) for the 5d transition metal elements Hf-Pt have been optimized for use in density fitting second-order Møller-Plesset perturbation theory and other correlated ab initio methods. Calculations of the second-order Møller-Plesset perturbation theory correlation energy, for a test set of small to medium sized molecules, indicate that the density fitting error when utilizing these sets is negligible at three to four orders of magnitude smaller than the orbital basis set incompleteness error.
Strong correlations between vacancy and magnetic ordering in superconducting K0.8Fe2 -ySe2
NASA Astrophysics Data System (ADS)
Yang, J.; Duan, C.; Huang, Q.; Brown, C.; Neuefeind, J.; Louca, Despina
2016-07-01
The coexistence of magnetic and nonmagnetic phases in the superconducting potassium iron selenide, KxFe2 -ySe2 , has been intensely debated. With superconductivity proposed to appear in a stoichiometric, nonmagnetic phase with I4/mmm crystal symmetry, the proposed nonsuperconducting phase is magnetic and has a lower symmetry, I4/m. The latter consists of Fe vacancies that go through a disordered-to-ordered transition in which the partially filled Fe sites create a supercell upon ordering. We show, using neutron scattering on the optimally doped composition, K0.8Fe2 -ySe2 , that the absence of magnetism does not signal the presence of superconductivity. Moreover, the degree of vacancy order is coupled to the strength of the magnetic order. Superconductivity coincides with the presence of the magnetic order parameter, albeit the latter is significantly weaker than previously reported, contradicting the current understanding of this ˜30 K superconductor.
Goicoechea, Héctor C; Olivieri, Alejandro C; Tauler, Romà
2010-03-01
Correlation constrained multivariate curve resolution-alternating least-squares is shown to be a feasible method for processing first-order instrumental data and achieve analyte quantitation in the presence of unexpected interferences. Both for simulated and experimental data sets, the proposed method could correctly retrieve the analyte and interference spectral profiles and perform accurate estimations of analyte concentrations in test samples. Since no information concerning the interferences was present in calibration samples, the proposed multivariate calibration approach including the correlation constraint facilitates the achievement of the so-called second-order advantage for the analyte of interest, which is known to be present for more complex higher-order richer instrumental data. The proposed method is tested using a simulated data set and two experimental data systems, one for the determination of ascorbic acid in powder juices using UV-visible absorption spectral data, and another for the determination of tetracycline in serum samples using fluorescence emission spectroscopy.
Rekker, Roderik; Keijsers, Loes; Branje, Susan; Meeus, Wim
2015-06-01
This three-wave cohort-sequential longitudinal study (N = 1302) examined the development of two core political attitudes, economic egalitarianism and ethnocentrism, among Dutch youths between age 12 and 31. Longitudinal regression analyses revealed a curvilinear mean level development for both attitudes, reflecting an increased disagreement with economic redistribution and multiculturalism around late adolescence. Furthermore, attitudes became decreasingly polarized (i.e., less extreme) and increasingly stable with age. Finally, several effects of attitudes' correlates gradually changed: The effect of educational level on ethnocentrism increased with age, whereas the effect of gender diminished. Regional effects on ethnocentrism developed as youths resided in a new area. No age-related change was found in the effect of parental SES. Overall, these findings support the idea that attitudes mature during the formative phase of adolescence and that this process slows down during emerging adulthood. Furthermore, these results support developmental explanations for the association between attitudes and their correlates.
Green, Anthony J; Space, Brian
2015-07-23
Sum frequency vibrational spectroscopy (SFVS), a second-order optical process, is interface-specific in the dipole approximation [Perry, A.; Neipert, C.; Moore, P.; Space, B. Chem. Rev. 2006, 106, 1234-1258; Richmond, G. L. Chem. Rev. 2002, 102, 2693-2724; Byrnes, S. J.; Geissler, P. L.; Shen, Y. R. Chem. Phys. Lett. 2011, 516, 115-124]. At charged interfaces, the experimentally detected signal is a combination of enhanced second-order and static-field-induced third-order contributions due to the existence of a static field. Evidence of the importance/relative magnitude of this third-order contribution is seen in the literature [Ong, S.; Zhao, X.; Eisenthal, K. B. Chem. Phys. Lett. 1992, 191, 327-335; Zhao, X.; Ong, S.; Eisenthal, K. B. Chem. Phys. Lett. 1993, 202, 513-520; Shen, Y. R. Appl. Phys. B: Laser Opt. 1999, 68, 295-300], but a molecularly detailed approach to separately calculating the second- and third-order contributions is difficult to construct. Recent work presented a novel molecular dynamics (MD)-based theory that provides a direct means to calculate the third-order contributions to SFVS spectra at charged interfaces [Neipert, C.; Space, B. J. Chem. Phys. 2006, 125, 224706], and a hyperpolarizability model for water was developed as a prerequisite to practical implementation [Neipert, C.; Space, B. Comput. Lett. 2007, 3, 431-440]. Here, these methods are applied to a highly abstracted/idealized silica/water interface, and the results are compared to experimental data for water at a fused quartz surface. The results suggest that such spectra have some quite general spectral features.
ERIC Educational Resources Information Center
Rekkas, P. V.; Westerveld, M.; Skudlarski, P.; Zumer, J.; Pugh, K.; Spencer, D. D.; Constable, R. T.
2005-01-01
The retrieval of temporal-order versus spatial-location information was investigated using fMRI. The primary finding in the hippocampus proper, seen in region of interest analyses, was an increase in BOLD signal intensity for temporal retrieval, and a decrease in signal intensity for spatial retrieval, relative to baseline. The negative BOLD…
Evidence for unusual superconducting correlations coexisting with stripe order in La1.875Ba0.125CuO4
NASA Astrophysics Data System (ADS)
Tranquada, J. M.; Gu, G. D.; Hücker, M.; Jie, Q.; Kang, H.-J.; Klingeler, R.; Li, Q.; Tristan, N.; Wen, J. S.; Xu, G. Y.; Xu, Z. J.; Zhou, J.; v. Zimmermann, M.
2008-11-01
We present new x-ray and neutron-scattering measurements of stripe order in La1.875Ba0.125CuO4 , along with low-field susceptibility, thermal conductivity, and specific-heat data. We compare these with previously reported results for resistivity and thermopower. Temperature-dependent features indicating transitions (or crossovers) are correlated among the various experimental quantities. Taking into account recent spectroscopic studies, we argue that the most likely interpretation of the complete collection of results is that an unusual form of two-dimensional superconducting correlations appears together with the onset of spin-stripe order. Recent theoretical proposals for a sinusoidally modulated superconducting state compatible with stripe order provide an intriguing explanation of our results and motivate further experimental tests. We also discuss evidence for one-dimensional pairing correlations that appear together with the charge order. With regard to the overall phenomenology, we consider the degree to which similar behavior may have been observed in other cuprates and describe possible connections to various puzzling phenomena in cuprate superconductors.
Wargacki, Stephen P; Pate, Brian; Vaia, Richard A
2008-05-20
Biological colloids, and in particular viruses, have demonstrated substantial potential as scaffolds for nanoparticle arrays. However, the large-area, low-cost, and rapid assembly of viruses, such as by traditional colloidal processing techniques, is not well-established. Systematic exploration of processing space (virus concentration, assembly speed, and substrate surface energy) for the convective assembly method enables the fabrication of films of rod-shaped viruses (tobacco mosaic virus, TMV) with a high degree of long-range order. Monolayer assemblies several centimeters in length are comprised of TMV aligned parallel to the direction of assembly. Increasing TMV concentration and reducing assembly speed resulted in well-ordered viral layering ( N = 2 to N = 12); however, the top virus layer exhibits varying degrees of in-plane disorder.
Symmetry and correlations underlying hidden order in URu_{2}Si_{2}
Butch, Nicholas P.; Manley, Michael E.; Jeffries, Jason R.; Janoschek, Marc; Huang, Kevin; Maple, M. Brian; Said, Ayman H.; Leu, Bogdan M.; Lynn, Jeffrey W.
2015-01-26
In this paper, we experimentally investigate the symmetry in the hidden order (HO) phase of intermetallic URu_{2}Si_{2} by mapping the lattice and magnetic excitations via inelastic neutron and x-ray scattering measurements in the HO and high-temperature paramagnetic phases. At all temperatures, the excitations respect the zone edges of the body-centered tetragonal paramagnetic phase, showing no signs of reduced spatial symmetry, even in the HO phase. The magnetic excitations originate from transitions between hybridized bands and track the Fermi surface, whose features are corroborated by the phonon measurements. Due to a large hybridization energy scale, a full uranium moment persists in the HO phase, consistent with a lack of observed crystal-field-split states. Our results are inconsistent with local order-parameter models and the behavior of typical density waves. Finally, we suggest that an order parameter that does not break spatial symmetry would naturally explain these characteristics.
NASA Astrophysics Data System (ADS)
Briggs, J. P.; Pennycook, S. J.; Fergusson, J. R.; Jäykkä, J.; Shellard, E. P. S.
2016-04-01
We present a case study describing efforts to optimise and modernise ;Modal;, the simulation and analysis pipeline used by the Planck satellite experiment for constraining general non-Gaussian models of the early universe via the bispectrum (or three-point correlator) of the cosmic microwave background radiation. We focus on one particular element of the code: the projection of bispectra from the end of inflation to the spherical shell at decoupling, which defines the CMB we observe today. This code involves a three-dimensional inner product between two functions, one of which requires an integral, on a non-rectangular domain containing a sparse grid. We show that by employing separable methods this calculation can be reduced to a one-dimensional summation plus two integrations, reducing the overall dimensionality from four to three. The introduction of separable functions also solves the issue of the non-rectangular sparse grid. This separable method can become unstable in certain scenarios and so the slower non-separable integral must be calculated instead. We present a discussion of the optimisation of both approaches. We demonstrate significant speed-ups of ≈100×, arising from a combination of algorithmic improvements and architecture-aware optimisations targeted at improving thread and vectorisation behaviour. The resulting MPI/OpenMP hybrid code is capable of executing on clusters containing processors and/or coprocessors, with strong-scaling efficiency of 98.6% on up to 16 nodes. We find that a single coprocessor outperforms two processor sockets by a factor of 1.3× and that running the same code across a combination of both microarchitectures improves performance-per-node by a factor of 3.38×. By making bispectrum calculations competitive with those for the power spectrum (or two-point correlator) we are now able to consider joint analysis for cosmological science exploitation of new data.
Briggs, J.P.; Pennycook, S.J.; Fergusson, J.R.; Jäykkä, J.; Shellard, E.P.S.
2016-04-01
We present a case study describing efforts to optimise and modernise “Modal”, the simulation and analysis pipeline used by the Planck satellite experiment for constraining general non-Gaussian models of the early universe via the bispectrum (or three-point correlator) of the cosmic microwave background radiation. We focus on one particular element of the code: the projection of bispectra from the end of inflation to the spherical shell at decoupling, which defines the CMB we observe today. This code involves a three-dimensional inner product between two functions, one of which requires an integral, on a non-rectangular domain containing a sparse grid. We show that by employing separable methods this calculation can be reduced to a one-dimensional summation plus two integrations, reducing the overall dimensionality from four to three. The introduction of separable functions also solves the issue of the non-rectangular sparse grid. This separable method can become unstable in certain scenarios and so the slower non-separable integral must be calculated instead. We present a discussion of the optimisation of both approaches. We demonstrate significant speed-ups of ≈100×, arising from a combination of algorithmic improvements and architecture-aware optimisations targeted at improving thread and vectorisation behaviour. The resulting MPI/OpenMP hybrid code is capable of executing on clusters containing processors and/or coprocessors, with strong-scaling efficiency of 98.6% on up to 16 nodes. We find that a single coprocessor outperforms two processor sockets by a factor of 1.3× and that running the same code across a combination of both microarchitectures improves performance-per-node by a factor of 3.38×. By making bispectrum calculations competitive with those for the power spectrum (or two-point correlator) we are now able to consider joint analysis for cosmological science exploitation of new data.
NASA Astrophysics Data System (ADS)
Ohta, Mitsuo; Ogawa, Hitoshi; Ikuta, Akira
2005-08-01
A probabilistic signal processing method, with which is possible to get some methodological suggestion to the measurement method of correlative and/or accumulative effects in the compound environment of sound, light and electromagnetic (EM) waves is discussed. In order to extract various types of latent interrelation characteristics among wave environmental factors leaked from an actually operating video display terminal (VDT), an extended regression system model, hierarchically reflecting not only linear correlation information but also nonlinear correlation information, is first introduced, especially from a viewpoint of 'relationism-first'. Then, through estimating each regression parameter of this model, some original evaluation methods for predicting a whole probability distribution form, from one another, are proposed. Finally, the effectiveness of the methods is experimentally confirmed, by applying them to the actual observed data leaked by a VDT with some television games. To cite this article: M. Ohta et al., C. R. Mecanique 333 (2005).
Lochan, Rohini C.; Head-Gordon, Martin
2007-01-01
Coupled cluster methods based on Brueckner orbitals are well-known to resolve the problems of symmetry-breaking and spin-contamination that are often associated with Hartree-Fock orbitals. However their computational cost is large enough to prevent application to large molecules. Here they present a simple approximation where the orbitals are optimized with the mean-field energy plus a correlation energy taken as the opposite-spin component of the second order many-body correlation energy, scaled by an empirically chosen parameter (recommended as 1.2 for general applications). This optimized 2nd order opposite spin (abbreviated as O2) method requires fourth order computation on each orbital iteration. O2 is shown to yield predictions of structure and frequencies for closed shell molecules that are very similar to scaled second order Moller-Plesset methods. However it yields substantial improvements for open shell molecules, where problems with spin-contamination and symmetry breaking are shown to be greatly reduced.
Steele, Ryan P; DiStasio, Robert A; Shao, Yihan; Kong, Jing; Head-Gordon, Martin
2006-08-21
The resolution-of-the-identity (RI) approximation has placed the onus of the cost of a second-order Moller-Plesset (MP2) calculation on the underlying self-consistent field (SCF) calculation for many moderately sized molecules. A dual-basis approach to the SCF calculation, based on previous methods demonstrated for density functional theory, is combined with RI-MP2 calculations, and small basis subsets for cc-pVTZ, cc-pVQZ, and 6-311++G(3df,3pd) are presented. These subsets provide time savings of greater than 90%, with negligible errors in absolute and relative energies, compared to the associated full-basis counterpart. The method is tested with a series of rotational barriers, relative conformational energies of alanine tetrapeptides, as well as the full G3/99 molecular set. RI-MP2 calculations on alanine octapeptides (40 heavy atoms, 3460 basis functions), using cc-pVQZ, are presented. Results improve upon previous methods that diagonalize the virtual space separately.
NASA Astrophysics Data System (ADS)
Yang, X. I. A.; Marusic, I.; Meneveau, C.
2016-06-01
Townsend [Townsend, The Structure of Turbulent Shear Flow (Cambridge University Press, Cambridge, UK, 1976)] hypothesized that the logarithmic region in high-Reynolds-number wall-bounded flows consists of space-filling, self-similar attached eddies. Invoking this hypothesis, we express streamwise velocity fluctuations in the inertial layer in high-Reynolds-number wall-bounded flows as a hierarchical random additive process (HRAP): uz+=∑i=1Nzai . Here u is the streamwise velocity fluctuation, + indicates normalization in wall units, z is the wall normal distance, and ai's are independently, identically distributed random additives, each of which is associated with an attached eddy in the wall-attached hierarchy. The number of random additives is Nz˜ln(δ /z ) where δ is the boundary layer thickness and ln is natural log. Due to its simplified structure, such a process leads to predictions of the scaling behaviors for various turbulence statistics in the logarithmic layer. Besides reproducing known logarithmic scaling of moments, structure functions, and correlation function [" close="]3/2
Mukaida, Makoto; Sato, Haruna; Sugano, Kiyohiko; Terada, Katsuhide
2017-01-01
The aim of this study was to determine the thermodynamic stability order of co-crystals using co-crystal former exchange reactions and to validate 2 in silico parameters for predicting co-crystal formation. Co-crystal former exchange reactions were performed using acetaminophen (AC) co-crystals of oxalic acid (OX), maleic acid (MA), and theophylline (TH). The addition of TH to an AC-MA co-crystal (AC-MA) afforded AC-TH, suggesting that AC-TH was more stable than AC-MA. The stability order among the other co-crystals was determined in the same manner. The stability order of the AC co-crystals was determined to be AC-TH > AC-MA ≈ AC-OX. Interestingly, the addition of TH to AC-OX afforded TH-OX. The stability order of the TH co-crystals was also determined (OX-TH > AC-TH ≈ MA-TH). Although the stability order of the AC co-crystals was consistent with the differences in their hydrogen bond energy (ΔE), an in silico parameter for predicting co-crystal formation, it showed no relationship to the excess enthalpy (Hex). These results suggest that co-crystal formation can be predicted with greater accuracy using ΔE rather than Hex for AC co-crystals. The stability orders of the AC and TH co-crystals also correlated well with their melting points and disintegration temperatures.
NASA Astrophysics Data System (ADS)
Haendel, A.; Ohrnberger, M.; Krüger, F.
2016-11-01
Knowledge of the quality factor of near-surface materials is of fundamental interest in various applications. Attenuation can be very strong close to the surface and thus needs to be properly assessed. In recent years, several researchers have studied the retrieval of attenuation coefficients from the cross correlation of ambient seismic noise. Yet, the determination of exact amplitude information from noise-correlation functions is, in contrast to the extraction of traveltimes, not trivial. Most of the studies estimated attenuation coefficients on the regional scale and within the microseism band. In this paper, we investigate the possibility to derive attenuation coefficients from seismic noise at much shallower depths and higher frequencies (>1 Hz). The Euroseistest area in northern Greece offers ideal conditions to study quality factor retrieval from ambient noise for different rock types. Correlations are computed between the stations of a small scale array experiment (station spacings <2 km) that was carried out in the Euroseistest area in 2011. We employ the correlation of the coda of the correlation (C3) method instead of simple cross correlations to mitigate the effect of uneven noise source distributions on the correlation amplitude. Transient removal and temporal flattening are applied instead of 1-bit normalization in order to retain relative amplitudes. The C3 method leads to improved correlation results (higher signal-to-noise ratio and improved time symmetry) compared to simple cross correlations. The C3 functions are rotated from the ZNE to the ZRT system and we focus on Love wave arrivals on the transverse component and on Love wave quality factors QL. The analysis is performed for selected stations being either situated on soft soil or on weathered rock. Phase slowness is extracted using a slant-stack method. Attenuation parameters are inferred by inspecting the relative amplitude decay of Love waves with increasing interstation distance. We
Dai, Ling -Yun; Kang, Zhong -Bo; Prokudin, Alexei; ...
2015-12-22
Here, we study the Sivers asymmetry in semi-inclusive hadron production in deep inelastic scattering. We concentrate on the contribution from the photon-gluon fusion channel at O(αem2αs), where three-gluon correlation functions play a major role within the twist-3 collinear factorization formalism. We establish the correspondence between such a formalism with three-gluon correlation functions and the usual transverse momentum-dependent (TMD) factorization formalism at moderate hadron transverse momenta. We derive the coefficient functions used in the usual TMD evolution formalism related to the quark Sivers function expansion in terms of the three-gluon correlation functions. We further perform the next-to-leading order calculation for themore » transverse momentum-weighted spin-dependent differential cross section and identify the off-diagonal contribution from the three-gluon correlation functions to the QCD collinear evolution of the twist-3 Qiu-Sterman function.« less
Dai, Ling -Yun; Kang, Zhong -Bo; Prokudin, Alexei; Vitev, Ivan
2015-12-22
Here, we study the Sivers asymmetry in semi-inclusive hadron production in deep inelastic scattering. We concentrate on the contribution from the photon-gluon fusion channel at O(α_{em}^{2}α_{s}), where three-gluon correlation functions play a major role within the twist-3 collinear factorization formalism. We establish the correspondence between such a formalism with three-gluon correlation functions and the usual transverse momentum-dependent (TMD) factorization formalism at moderate hadron transverse momenta. We derive the coefficient functions used in the usual TMD evolution formalism related to the quark Sivers function expansion in terms of the three-gluon correlation functions. We further perform the next-to-leading order calculation for the transverse momentum-weighted spin-dependent differential cross section and identify the off-diagonal contribution from the three-gluon correlation functions to the QCD collinear evolution of the twist-3 Qiu-Sterman function.
NASA Astrophysics Data System (ADS)
Suhai, Sándor
1994-11-01
Linear equidistant and bond-alternating infinite chains of hydrogen atoms have been investigated by the ab initio crystal-orbital method at the Hartree-Fock (HF) level, by including electron correlation up to the complete fourth order of the Mo/ller-Plesset perturbation theory (MP4-PT), and by using different versions of density-functional theory (DFT). The Bloch functions have been expanded in all cases in a series of high-quality atomic-orbital basis sets and complemented by extended sets of polarization functions up to 6s3p2d1f per H atom. In order to compare the performance of the PT and DFT methods, several physical properties have been computed at all theoretical levels including lattice geometry, cohesive energy, mechanisms of bond alternation (Peierls instability), and energetic features of nonequilibrium configurations (dissociation). For these latter quantities, both spin-restricted (RHF) and unrestricted (UHF) wave functions have been employed in all orders of PT. The methods described have been used parallel to infinite chains and to the H2 molecule, to be able to check their accuracy on experiments. In the case of the DFT, six different functionals (combining Slater and Becke exchange with local and gradient-corrected correlation potentials) have been utilized to test their accuracy in comparison with the MP4 results.
Arora, Priya; Moudgil, R. K.; Bhukal, Nisha
2015-05-15
Static density-density correlation function has been calculated for a spin-polarized two-dimensional quantum electron fluid by including the first-order exchange and self-energy corrections to the random-phase approximation (RPA). This is achieved by determining these corrections to the RPA linear density-density response function, obtained by solving the equation of motion for the single-particle Green’s function. Resulting infinite hierarchy of equations (involving higher-order Green’s functions) is truncated by factorizing the two-particle Green’s function as a product of the single-particle Green’s function and one-particle distribution function. Numerical results of correlation function are compared directly against the quantum Monte Carlo simulation data due to Tanatar and Ceperley for different coupling parameter (r{sub s}) values. We find almost exact agreement for r{sub s}=1, with a noticeable improvement over the RPA. Its quality, however, deteriorates with increasing r{sub s}, but correction to RPA is quite significant.
NASA Technical Reports Server (NTRS)
Moore, C. E.; Cardelino, B. H.; Frazier, D. O.; Niles, J.; Wang, X.-Q.
1998-01-01
The static third-order polarizabilities (gamma) of C60, C70, five isomers of C78 and two isomers of C84 were analyzed in terms of three properties, from a geometric point of view: symmetry, aromaticity and size. The polarizability values were based on the finite field approximation using a semiempirical Hamiltonian (AM1) and applied to molecular structures obtained from density functional theory calculations. Symmetry was characterized by the molecular group order. The selection of 6-member rings as aromatic was determined from an analysis of bond lengths. Maximum interatomic distance and surface area were the parameters considered with respect to size. Based on triple linear regression analysis, it was found that the static linear polarizability (alpha) and gamma in these molecules respond differently to geometrical properties: alpha depends almost exclusively on surface area while gamma is affected by a combination of number of aromatic rings, length and group order, in decreasing importance. In the case of alpha, valence electron contributions provide the same information as all-electron estimates. For gamma, the best correlation coefficients are obtained when all-electron estimates are used and when the dependent parameter is ln(gamma) instead of gamma.
Masud, Md G.; Dey, K.; Ghosh, A.; Majumdar, S.; Giri, S.
2015-08-14
Magnetic, dielectric, and ac conductivity as well as room temperature structural and Raman studies are performed on double perovskite Dy{sub 2}NiMnO{sub 6}. The crystal structure of the compound adopts monoclinic P2{sub 1}/n space group, where alternate Mn and Ni distorted octahedral are arranged in anti-phase a{sup −} a{sup −} b{sup +} order in Glazer notation. Magnetization studies show two magnetic transitions around 100 K and 20 K which are related to the ordering of transition and rare earth cations moment, respectively. Temperature dependent dielectric permittivity shows Havriliak-Negami type thermally activated dielectric relaxation. The ac conductivity at different temperature is found to follow Jonscher power law behavior. Time-temperature scaling of the conductivity spectra reveals that the charge transport dynamics is independent of temperature. Intriguingly, an anomaly in the dielectric constant is observed close to the order of Dy moment which indicates intrinsic magnetoelectric coupling. The hybridization between Dy and Ni/Mn is suggested to be correlated with the magnetoelectric coupling.
NASA Astrophysics Data System (ADS)
Kovalev, A.; Filippov, A.; Gorb, S. N.
2016-03-01
In contrast to the majority of inorganic or artificial materials, there is no ideal long-range ordering of structures on the surface in biological systems. Local symmetry of the ordering on biological surfaces is also often broken. In the present paper, the particular symmetry violation was analyzed for dimple-like nano-pattern on the belly scales of the skin of the pythonid snake Morelia viridis using correlation analysis and statistics of the distances between individual nanostructures. The results of the analysis performed on M. viridis were compared with a well-studied nano-nipple pattern on the eye of the sphingid moth Manduca sexta, used as a reference. The analysis revealed non-random, but very specific symmetry violation. In the case of the moth eye, the nano-nipple arrangement forms a set of domains, while in the case of the snake skin, the nano-dimples arrangement resembles an ordering of particles (molecules) in amorphous (glass) state. The function of the nano-dimples arrangement may be to provide both friction and strength isotropy of the skin. A simple model is suggested, which provides the results almost perfectly coinciding with the experimental ones. Possible mechanisms of the appearance of the above nano-formations are discussed.
NASA Astrophysics Data System (ADS)
Srivastava, A. P.; Srivastava, D.; Sudarshan, K.; Sharma, S. K.; Pujari, P. K.; Majumdar, B.; Suresh, K. G.; Dey, G. K.
2012-08-01
Amorphous ribbons of different thicknesses of Co64.5Fe3.5Si16B14Ni2 alloy were synthesized using the melt spinning technique by varying wheel speed. The effect of cooling rate on the ribbon thickness and their soft magnetic properties have been studied. The amorphous structure has been characterized in terms of structural free volume and medium range order (MRO) by positron annihilation spectroscopy and fluctuation electron microscopy techniques. Positron lifetime spectra of amorphous samples showed two lifetime components. The first component was found to be correlated with MRO whereas, the second lifetime component was found to be associated with nanovoid type of defects, and the second component was strongly dependent on processing conditions. It could be established that the coercivity of the amorphous samples produced by the rapid solidification technique mainly depends on the defects formed during processing rather than change induced in MRO.
NASA Astrophysics Data System (ADS)
Pavošević, Fabijan; Pinski, Peter; Riplinger, Christoph; Neese, Frank; Valeev, Edward F.
2016-04-01
We present a formulation of the explicitly correlated second-order Møller-Plesset (MP2-F12) energy in which all nontrivial post-mean-field steps are formulated with linear computational complexity in system size. The two key ideas are the use of pair-natural orbitals for compact representation of wave function amplitudes and the use of domain approximation to impose the block sparsity. This development utilizes the concepts for sparse representation of tensors described in the context of the domain based local pair-natural orbital-MP2 (DLPNO-MP2) method by us recently [Pinski et al., J. Chem. Phys. 143, 034108 (2015)]. Novel developments reported here include the use of domains not only for the projected atomic orbitals, but also for the complementary auxiliary basis set (CABS) used to approximate the three- and four-electron integrals of the F12 theory, and a simplification of the standard B intermediate of the F12 theory that avoids computation of four-index two-electron integrals that involve two CABS indices. For quasi-1-dimensional systems (n-alkanes), the O (" separators="N ) DLPNO-MP2-F12 method becomes less expensive than the conventional O (" separators="N5 ) MP2-F12 for n between 10 and 15, for double- and triple-zeta basis sets; for the largest alkane, C200H402, in def2-TZVP basis, the observed computational complexity is N˜1.6, largely due to the cubic cost of computing the mean-field operators. The method reproduces the canonical MP2-F12 energy with high precision: 99.9% of the canonical correlation energy is recovered with the default truncation parameters. Although its cost is significantly higher than that of DLPNO-MP2 method, the cost increase is compensated by the great reduction of the basis set error due to explicit correlation.
Quickel, Thomas E; Le, Van H; Brezesinski, Torsten; Tolbert, Sarah H
2010-08-11
In this work, we report the synthesis of periodic nanoporous cobalt ferrite (CFO) that exhibits tunable room temperature ferrimagnetism. The porous cubic CFO frameworks are fabricated by coassembly of inorganic precursors with a large amphiphilic diblock copolymer, referred to as KLE. The inverse spinel framework boasts an ordered open network of pores averaging 14 nm in diameter. The domain sizes of the crystallites are tunable from 6 to 15 nm, a control which comes at little cost to the ordering of the mesostructure. Increases in crystalline domain size directly correlate with increases in room temperature coercivity. In addition, these materials show a strong preference for out-of-plane oriented magnetization, which is unique in a thin film system. The preference is explained by in-plane tensile strain, combined with relaxation of the out-of-plane strain through flexing of the mesopores. It is envisioned that the pores of this ferrimagnet could facilitate the formation of a diverse range of exchange coupled composite materials.
Jakse, N.; Pasturel, A.
2015-08-28
We use ab initio molecular dynamics simulations to study the correlation between the local ordering and the dynamic properties of liquid Al{sub 80}Ni{sub 20} alloy upon cooling. Our results evidence a huge increase of local icosahedral ordering (ISRO) in the undercooled regime which is more developed around Ni than Al atoms. We show that ISRO has a strong impact on self-diffusion coefficients of both species and is at the origin of their crossover from Arrhenius to non-Arrhenius behavior around a crossover temperature T{sub X} = 1000 K, located in the undercooled region. We also clearly identify that this temperature corresponds to the development of dynamic heterogeneities and to the breakdown of the Stokes-Einstein relation. At temperatures below this crossover, we find that the behavior of the diffusion and relaxation dynamics is mostly incompatible with predictions of the mode-coupling theory. Finally, an analysis of the van Hove function indicates that the crossover temperature T{sub X} marks the onset of a change in the diffusion mechanism from a normal flow to an activated process with hopping. From these results, the glass-forming ability of the alloy is discussed.
NASA Astrophysics Data System (ADS)
Bachinskyi, V. T.; Popovych, D. T.; Wanchuliak, O. Y.
2012-01-01
A new approach for monitoring temporal changes in the optical anisotropy of the human eye tissue after death was proposed. The basis of the research study assigned degree of depolarization of laser radiation, converted collagen networks vitreous of the eye.The optical model of polycrystalline networks of vitreous body histological sections is suggested. The results of investigating the interrelation between the values of statistical (statistical moments of the 1st-4th order), correlation (correlation area, asymmetry coefficient and autocorrelation function excess) and fractal (dispersion of logarithmic dependencies of power spectra) parameters are presented. They characterize the coordinate distributions of phase shifts between the orthogonal components of the amplitude in the points of laser images of histological sections of vitreous body and temporal dynamics of optical anisotropy of this biological object. The diagnostic criteria of death coming prescription are determined.
NASA Astrophysics Data System (ADS)
Bachinskyi, V. T.; Popovych, D. T.; Wanchuliak, O. Y.
2011-09-01
A new approach for monitoring temporal changes in the optical anisotropy of the human eye tissue after death was proposed. The basis of the research study assigned degree of depolarization of laser radiation, converted collagen networks vitreous of the eye.The optical model of polycrystalline networks of vitreous body histological sections is suggested. The results of investigating the interrelation between the values of statistical (statistical moments of the 1st-4th order), correlation (correlation area, asymmetry coefficient and autocorrelation function excess) and fractal (dispersion of logarithmic dependencies of power spectra) parameters are presented. They characterize the coordinate distributions of phase shifts between the orthogonal components of the amplitude in the points of laser images of histological sections of vitreous body and temporal dynamics of optical anisotropy of this biological object. The diagnostic criteria of death coming prescription are determined.
Method for breast cancer diagnosis by phase spectrophotometry of human blood plasma
NASA Astrophysics Data System (ADS)
Mintser, Ozar P.; Oliinychenko, B. P.
2012-01-01
The possibility of breast cancer diagnostics by means of phase structure measurements of laser radiation transformed by human blood plasma samples. The theoretical fundamentals of polarization filtration method for direct phase shifts measurements of microscopic images are provided. The optical model of polycrystalline networks of blood plasma proteins is suggested. The results of investigating the interrelation between the values of statistical (statistical moments of the 1st-4th order), correlation (correlation area, asymmetry coefficient and autocorrelation function excess) and fractal (dispersion of logarithmic dependencies of power spectra) parameters are presented. They characterize the coordinate distributions of phase shifts between the orthogonal components of the amplitude in the points of laser images of blood plasma smears and pathological changes in the mammary gland tissue. The diagnostic criteria of breast cancer nascency are determined.
Method for breast cancer diagnosis by phase spectrophotometry of human blood plasma
NASA Astrophysics Data System (ADS)
Mintser, Ozar P.; Oliinychenko, B. P.
2011-09-01
The possibility of breast cancer diagnostics by means of phase structure measurements of laser radiation transformed by human blood plasma samples. The theoretical fundamentals of polarization filtration method for direct phase shifts measurements of microscopic images are provided. The optical model of polycrystalline networks of blood plasma proteins is suggested. The results of investigating the interrelation between the values of statistical (statistical moments of the 1st-4th order), correlation (correlation area, asymmetry coefficient and autocorrelation function excess) and fractal (dispersion of logarithmic dependencies of power spectra) parameters are presented. They characterize the coordinate distributions of phase shifts between the orthogonal components of the amplitude in the points of laser images of blood plasma smears and pathological changes in the mammary gland tissue. The diagnostic criteria of breast cancer nascency are determined.
NASA Astrophysics Data System (ADS)
Autschbach, Jochen
2013-09-01
The relativistic NMR module of the Amsterdam Density Functional (ADF) package, which is frequently utilised in studies of heavy atom NMR chemical shifts, is extended to calculate a hitherto neglected term from the response of the exchange-correlation (XC) potential. The term vanishes in the absence of spin-orbit coupling. Further, corrections to the shielding arising from scaling factors in the zeroth-order regular approximation (zora) relativistic framework are investigated. The XC response markedly improves calculated proton chemical shifts for hydrogen halides. Mercury chemical shifts for mercury dihalides are also noticeably altered. Contributions from density-gradient dependent terms in the response kernel contribute about 30-40%. New fully relativistic density functional theory (DFT) benchmark data are compared with zora and literature reference values. In line with previous work, it is found that absolute shielding constants for Hg are not accurately predicted with zora. However, chemical shifts agree well with fully relativistic calculations. The application of 'scaled-zora' scaling factors deteriorates the shielding constants and is therefore not recommended. The scaling hardly affects chemical shifts. zora calculations are not suitable for absolute shielding of heavy atoms but they can be used safely for chemical shifts in most application scenarios.
NASA Astrophysics Data System (ADS)
Ann, Byoung-moo; Song, Younghoon; Kim, Junki; Yang, Daeho; An, Kyungwon
2015-08-01
Exact measurement of the second-order correlation function g(2 )(t ) of a light source is essential when investigating the photon statistics and the light generation process of the source. For a stationary single-mode light source, the Mandel Q factor is directly related to g(2 )(0 ) . For a large mean photon number in the mode, the deviation of g(2 )(0 ) from unity is so small that even a tiny error in measuring g(2 )(0 ) would result in an inaccurate Mandel Q . In this work, we address the detector-dead-time effect on g(2 )(0 ) of stationary sub-Poissonian light. It is then found that detector dead time can induce a serious error in g(2 )(0 ) and thus in Mandel Q in those cases even in a two-detector configuration. Utilizing the cavity-QED microlaser, a well-established sub-Poissonian light source, we measured g(2 )(0 ) with two different types of photodetectors with different dead times. We also introduced prolonged dead time by intentionally deleting the photodetection events following a preceding one within a specified time interval. We found that the observed Q of the cavity-QED microlaser was underestimated by 19% with respect to the dead-time-free Q when its mean photon number was about 600. We derived an analytic formula which well explains the behavior of the g(2 )(0 ) as a function of the dead time.
Correlation driven charge order at LaAlO3/SrTiO3 and LaTiO3/SrTiO3 Interfaces
NASA Astrophysics Data System (ADS)
Pentcheva, Rossitza
2007-03-01
Correlated behavior at complex oxide interfaces offers additional degrees of freedom to compensate charge imbalance not available e.g. in polar semiconductor heterostructures. This can result in electronic, charge and magnetic phases that do not exist in the bulk and offers new possibilities for device applications. For instance, the interfaces of LaTiO3 and SrTiO3 [1] as well as LaAlO3 and SrTiO3 [2] show metallic conductivity, although the respective bulk materials are Mott (LTO) and band insulating (STO, LAO). Here we present the results of material-specific correlated band theory (LDA+U) employing the FP-LAPW code in the WIEN2k implementation for a variety of (n,m) multilayers containing n LTO (or LAO) and m STO-layers. To explore the relaxation length towards bulk behavior n and m is varied between 1 and 9. We find that charge mismatch at the LTO/STO IF is accommodated by the formation of a charge and orbitally ordered (CO/OO) layer with a checkerboard arrangement of Ti^3+ and Ti^4+ and an antiferromagnetic coupling of the Ti^3+-spins [3]. Lattice relaxations lead to the observed conducting behavior. An analogous diluted layer of Ti^3+ spins is obtained for the n-type LAO/STO interface, although the corresponding bulk materials are nonmagnetic. For a structurally ideal p-type LAO/STO IF the measured insulating behavior can only be understood by a charge disproportionation on the oxygen sublattice and the formation of a CO/OO magnetic OPπ hole. Alternatively, charge compensation by oxygen vacancies and the formation of a charge conjugate F-center is considered. [1] A. Ohtomo, and H.Y. Hwang, Nature 423, 378 (2002). [2] A. Ohtomo, D.A. Muller, J.L. Grazul, and H.Y. Hwang, Nature 419, 378 (2002). [3] R. Pentcheva and W.E. Pickett, cond-mat/0608212. [4] R. Pentcheva and W.E. Pickett, Phys. Rev. B 74, 035112 (2006).
NASA Astrophysics Data System (ADS)
Ushenko, A. G.; Dubolazov, A. V.; Ushenko, V. A.; Ushenko, Yu. A.; Pidkamin, L. I.; Kushnerik, L. Y.; Gavrylyak, M. S.; Martseniak, I.; Oliinyk, I.; Grygorishin, P.
2016-09-01
The optical model of polycrystalline networks of human skin is suggested. The results of investigation of the values of statistical (statistical moments of the 1st-4th order) parameters of polarization inhomogeneous images of skin surface in Fourier domain are presented. The diagnostic criteria of pathological process in human skin and its severity degree differentiation are determined.
Li, G; Tyagi, N; Deasy, J; Wei, J; Hunt, M
2015-06-15
Purpose: Cine 2DMRI is useful in MR-guided radiotherapy but it lacks volumetric information. We explore the feasibility of estimating timeresolved (TR) 4DMRI based on cine 2DMRI and respiratory-correlated (RC) 4DMRI though simulation. Methods: We hypothesize that a volumetric image during free breathing can be approximated by interpolation among 3DMRI image sets generated from a RC-4DMRI. Two patients’ RC-4DMRI with 4 or 5 phases were used to generate additional 3DMRI by interpolation. For each patient, six libraries were created to have total 5-to-35 3DMRI images by 0–6 equi-spaced tri-linear interpolation between adjacent and full-inhalation/full-exhalation phases. Sagittal cine 2DMRI were generated from reference 3DMRIs created from separate, unique interpolations from the original RC-4DMRI. To test if accurate 3DMRI could be generated through rigid registration of the cine 2DMRI to the 3DMRI libraries, each sagittal 2DMRI was registered to sagittal cuts in the same location in the 3DMRI within each library to identify the two best matches: one with greater lung volume and one with smaller. A final interpolation between the corresponding 3DMRI was then performed to produce the first-order-approximation (FOA) 3DMRI. The quality and performance of the FOA as a function of library size was assessed using both the difference in lung volume and average voxel intensity between the FOA and the reference 3DMRI. Results: The discrepancy between the FOA and reference 3DMRI decreases as the library size increases. The 3D lung volume difference decreases from 5–15% to 1–2% as the library size increases from 5 to 35 image sets. The average difference in lung voxel intensity decreases from 7–8 to 5–6 with the lung intensity being 0–135. Conclusion: This study indicates that the quality of FOA 3DMRI improves with increasing 3DMRI library size. On-going investigations will test this approach using actual cine 2DMRI and introduce a higher order approximation for
NASA Technical Reports Server (NTRS)
Tiwari, S. N.; Manian, S. V. S.
1976-01-01
Various mathematical models for infrared radiation absorption spectra for atmospheric gases are reviewed, and continuous correlations for the total absorptance of a wide band are presented. Different band absorptance correlations were employed in two physically realistic problems (radiative transfer in gases with internal heat source, and heat transfer in laminar flow of absorbing-emitting gases between parallel plates) to study their influence on final radiative transfer results. This information will be applied to the study of atmospheric pollutants by infrared radiation measurement.
Ekman, Peik; Maula, Terhi; Yamaguchi, Shou; Yamamoto, Tetsuya; Nyholm, Thomas K M; Katsumura, Shigeo; Slotte, J Peter
2015-10-01
Ceramides and diacylglycerols are lipids with a large hydrophobic part (acyl chains and long-chain base) whereas their polar function (hydroxyl group) is small. They need colipids with large head groups to coexist in bilayer membranes. In this study, we have determined how saturated and unsaturated ceramides and acyl-chain matched diacylglycerols form ordered domains in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayers as a function of bilayer concentration. The formation of ordered domains was determined from lifetime analysis of trans-parinaric acid. Ceramides formed ordered domains with equal average tPA lifetime at lower bilayer concentration when compared to acyl-chain matched diacylglycerols. This was true for both saturated (16:0) and mono-unsaturated (18:1) species. This finding suggested that hydrogen bonding among ceramides contributed to their more efficient ordered phase formation, since diacylglycerols do not form similar hydrogen bonding networks. The role of hydrogen bonding in ordered domain formation was further verified by using palmitoyl ceramide analogs with 2N and 3OH methylated long-chain bases. These analogs do not form hydrogen bonds from the 2NH or the 3OH, respectively. While methylation of the 3OH did not affect ordered phase formation compared to native palmitoyl ceramide, 2NH methylation markedly attenuated ceramide ordered phase formation. We conclude that in addition to acyl chain length, saturation, molecular order, and lack of large head group, also hydrogen bonding involving the 2NH is crucial for efficient formation of ceramide-rich domains in fluid phosphatidylcholine bilayers.
Hill, J Grant
2013-09-30
Auxiliary basis sets (ABS) specifically matched to the cc-pwCVnZ-PP and aug-cc-pwCVnZ-PP orbital basis sets (OBS) have been developed and optimized for the 4d elements Y-Pd at the second-order Møller-Plesset perturbation theory level. Calculation of the core-valence electron correlation energies for small to medium sized transition metal complexes demonstrates that the error due to the use of these new sets in density fitting is three to four orders of magnitude smaller than that due to the OBS incompleteness, and hence is considered negligible. Utilizing the ABSs in the resolution-of-the-identity component of explicitly correlated calculations is also investigated, where it is shown that i-type functions are important to produce well-controlled errors in both integrals and correlation energy. Benchmarking at the explicitly correlated coupled cluster with single, double, and perturbative triple excitations level indicates impressive convergence with respect to basis set size for the spectroscopic constants of 4d monofluorides; explicitly correlated double-ζ calculations produce results close to conventional quadruple-ζ, and triple-ζ is within chemical accuracy of the complete basis set limit.
NASA Astrophysics Data System (ADS)
Fabbris, Gilberto; Hücker, Markus; Gu, Genda; Tranquada, John; Haskel, Daniel
2012-02-01
The strong Tc suppression in LaBaCuO at x=0.125 is widely believed to be related to formation of static stripes, at least partially driven by a strong electron-lattice coupling in a low temperature tetragonal (LTT) phase (Tranquada et al., Nature 375, 561 (1995)). A recent high-pressure experiment appears to challenge this view as it was observed that static stripe order persists to pressures higher than required to induce LTT to HTT transition (Hucker et al., PRL 104, 057004 (2010)). We carried out high-pressure La K-edge polarized XAFS measurements in LaBaCuO (x=0.125) single crystals in a diamond anvil cell to probe local CuO6 tilts. We observe that the local tilts remain LTT-like at high pressure, even though the macroscopic structure is HTT. The results suggest a significant order-disorder component to this pressure-induced phase transition, whereby the local LTT tilts remain present in the local scale but disorder over long range resulting in HTT symmetry seen by diffraction. The result may help explain why the stripe order is largely unaffected by the LTT to HTT pressure-induced transition. Work at Argonne (BNL) is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 (DE-AC02-98CH10886).
NASA Technical Reports Server (NTRS)
Langhoff, S. R.; Scott, W. R.; Suzuki, N.; Chong, D. P.
1979-01-01
Ordinary Rayleigh-Schroudinger perturbation theory with Moller-Plesset (RSMP) partitioning is used to calculate second- and third-order correlation corrections to the CHF polarizability and dipole moment of the water molecule by a finite-field procedure. Pade approximants are found to be useful in accelerating the convergence of the property perturbation expansions. Field-induced polarization functions suitable for polarizability calculations are determined. The average polarizability calculated, neglecting vibrational averaging, with Dunning's (9s5p/4s-4s2p/2s) contracted GTO basis set augmented by field-induced lslp2d/lp polarization functions is within 3 per cent of the experimental result. Correlation corrections to the dipole moment and polarizability of the water molecule calculated by the finite-field RSMP and single + double excitation CI(SDCI) methods for the same basis set are found to be in close agreement. The RSMP approach has the advantages of being size-consistent and of being capable of greater efficiency than the SCDI method. Comparative calculations carried out using Epstein-Nesbet partitioning show that through third order RSEN correlation perturbation expansions for the dipole moment and polarizability are less rapidly convergent than RSMP expansions. However, reasonable accord with RSMP results can be achieved by using Pade approximants to accelerate the convergence of RSEN energy perturbation expansions. The convergence of RSMP property correlation expansions based on the zeroth-order uncoupled-Hartree-Fock (UCHF) and coupled-Hartree-Fock (CHF) approximations are compared through third order. Whereas the CHF + RSMP expansions are for practical purposes fully converged, the UCHF + RSMP expansions are not adequately converged.
NASA Astrophysics Data System (ADS)
Shastry, B. Sriram; Perepelitsky, Edward
2016-07-01
We present the results for the low-energy properties of the infinite-dimensional t -J model with J =0 , using O (λ2) equations of the extremely correlated Fermi liquid formalism. The parameter λ ∈[0 ,1 ] is analogous to the inverse spin parameter 1 /(2 S ) in quantum magnets. The present analytical scheme allows us to approach the physically most interesting regime near the Mott insulating state n ≲1 . It overcomes the limitation to low densities n ≲0.7 of earlier calculations, by employing a variant of the skeleton graph expansion, and a high-frequency cutoff that is essential for maintaining the known high-T entropy. The resulting quasiparticle weight Z , the low ω ,T self-energy, and the resistivity are reported. These are quite close at all densities to the exact numerical results of the U =∞ Hubbard model, obtained using the dynamical mean field theory. The present calculation offers the advantage of generalizing to finite T rather easily, and allows the visualization of the loss of coherence of Fermi liquid quasiparticles by raising T . The present scheme is generalizable to finite dimensions and a nonvanishing J .
Słupski, R; Jankowski, K; Flores, J R
2016-09-14
Accurate Møller-Plesset (MP2) correlation energies calculated by means of the variational-perturbation and the finite-element methods are presented for several members of the Cu(+) isoelectronic series (N = 28), which represent closed-shell systems containing for the first time the 3d(10)-electron configuration and, consequently, closed M-shell. Total MP2 energies as well as their inner- and inter-shell components are reported for Cu(+), Zn(2+), Ge(4+), Kr(8+), Sr(10+), and Cd(20+). We found that for these ions the Z-dependence of the total MP2 energies is significantly weaker than for the members of the Ar-like series. The origin of this fact is rationalized by a detailed analysis performed at the levels of the shell- and inter-shell contributions to the MP2 energies. To get, for the first time, more general information about the (N, Z) characteristics of the MP2 energies for closed-shell atomic systems, we compare the Z-dependence of the Cu(+)-like systems with the MP2 energies calculated for other isoelectronic series. The weak Z-dependence is found for the He-, Ne-, and Cu(+)-like series, which consist of atoms having perfectly closed-shell K-, KL-, and KLM-electronic structures, respectively. In turn, for the Be-, Mg-, and Ar-series, the Z-dependence is considerably stronger.
ERIC Educational Resources Information Center
Gibeault, Michael
2005-01-01
Change orders. The words can turn the stomachs of administrators. Horror stories about change orders create fear and distrust among school officials, designers and builders. Can change orders be avoided? If car manufacturers can produce millions of intricately designed vehicles, why can't the same quality control be achieved on a construction…
Seidler, Tomasz; Stadnicka, Katarzyna; Champagne, Benoît
2014-05-13
The linear [χ((1))] and second-order nonlinear [χ((2))] optical susceptibilities of the 2-methyl-4-nitroaniline (MNA) crystal are calculated within the local field theory, which consists of first computing the molecular properties, accounting for the dressing effects of the surroundings, and then taking into account the local field effects. Several aspects of these calculations are tackled with the aim of monitoring the convergence of the χ((1)) and χ((2)) predictions with respect to experiment by accounting for the effects of (i) the dressing field within successive approximations, of (ii) the first-order ZPVA corrections, and of (iii) the geometry. With respect to the reference CCSD-based results, besides double hybrid functionals, the most reliable exchange-correlation functionals are LC-BLYP for the static χ((1)) and CAM-B3LYP (and M05-2X, to a lesser extent) for the dynamic χ((1)) but they strongly underestimate χ((2)). Double hybrids perform better for χ((2)) but not necessarily for χ((1)), and, moreover, their performances are much similar to MP2, which is known to slightly overestimate β, with respect to high-level coupled-clusters calculations and, therefore, χ((2)). Other XC functionals with less HF exchange perform poorly with overestimations/underestimations of χ((1))/χ((2)), whereas the HF method leads to underestimations of both. The first-order ZPVA corrections, estimated at the B3LYP level, are usually small but not negligible. Indeed, after ZPVA corrections, the molecular polarizabilities and first hyperpolarizabilities increase by 2% and 5%, respectively, whereas their impact is magnified on the macroscopic responses with enhancements of χ((1)) by up to 5% and of χ((2)) by as much as 10%-12% at λ = 1064 nm. The geometry plays also a key role in view of predicting accurate susceptibilities, particularly for push-pull π-conjugated compounds such as MNA. So, the geometry optimized using periodic boundary conditions is characterized
Jiang, Pengfei; Zhou, Zhengyang; Gao, Wenliang; Cong, Rihong; Yang, Tao
2016-03-07
The study of perovskites has been active for a long time. Here, we rationally designed and prepared a double perovskite, LaBaZnSbO6, by selecting Zn(2+) and Sb(5+) with large size and charge differences, and, indeed, complete B-site ordering can be achieved. Careful study using powder X-ray diffraction data pinpointed its space group to be I2/m, which has rarely been seen in double perovskites. Thereafter, an interesting observation of Sr(2+)-doping-induced symmetry evolution from I2/m to P21/n was confirmed in the complete solid solutions LaBa1-xSrxZnSbO6, where the tilting system also transferred from a(-)a(-)c(0) to a(-)a(-)c(+). The transition boundary is around x = 0.4. It can also be visualized by the variation of θ (defined as c/[(a + b)/2]), which is associated with the anisotropic shrinkage of the unit cell lattice and indeed shows a minimum at x = 0.4. Such a successive modulation of both the structural symmetry and the average La/Ba/Sr-O bond distances (revealed by Rietveld refinements) motivated us to study the Eu(3+) luminescence in La0.95Eu0.05Ba1-xSrxZnSbO6. Interestingly, the maximum of charge transfer absorption of Eu(3+) shows a precise changing tendency with the A-O bond distances along with the Sr(2+) doping, clearly revealing the structure-luminescence correlations.
Chmaissem, O.; Grigoraviciute, I.; Yamauchi, H.; Karppinen, M.; Marezio, M.
2010-01-01
A detailed study of the structure-property relationship is reported for the first four members of the high-T{sub c} superconducting homologous series of (Cu,Mo)Sr{sub 2}(Ce,Y){sub s}Cu{sub 2}O{sub 5+2s+{delta}} [(Cu,Mo)-12s2]. In this series, the adjacent CuO{sub 2} planes are separated by a single Y-cation layer for s=1 and a fluorite-type (Ce,Y)-[O{sub 2}-(Ce,Y)]{sub s-1} layer block for s {ge} 2. Even though this series may be considered a conventional homologous series from the chemical point of view, we emphasize that the structures are different from those of the Tl-, Hg-, Bi-, etc.,-based series by the fact that the inserted fluorite-type blocks are insulating. We show the formation of the higher s members via intercalation of additional Ce-O{sub 2} layer(s) into the crystal lattices of the lower members of the series. Neutron powder-diffraction data demonstrate that the Ce/Y ratio is not constant at the different (Ce,Y) layers in the fluorite-structured block and that the innermost (Ce,Y) layer(s) are significantly Ce rich compared with the outer ones. Two independent crystallographic sites are identified for the extra oxygen atoms in the basal (Cu{sub 0.75}Mo{sub 0.25})O{sub 1+{delta}} plane with site fractional occupancies that strongly correlate with the properties of the material. A short-range ordered structure is proposed for the (Cu{sub 0.75}Mo{sub 0.25})O{sub 1+{delta}} layers that could explain both the superconducting properties of the materials and the enhanced T{sub c} for the first member of the series.
Surface melting of electronic order.
Wilkins, S. B.; Liu, X.; Wakabayashi, Y.; Kim, J.-W.; Ryan, P. J.; Mitchell, J. F.; Hill, J. P.
2011-01-01
We report temperature-dependent surface x-ray scattering studies of the orbital ordered surface in La{sub 0.5}Sr{sub 1.5}MnO{sub 4}. We find that as the bulk ordering temperature is approached from below the thickness of the interface between the electronically ordered and electronically disordered regions at the surface grows, though the bulk correlation length remains unchanged. Close to the transition, the surface is so rough that there is no well-defined electronic surface, despite the presence of bulk electronic order. That is, the electronic ordering at the surface has melted. Above the bulk transition, long-range ordering in the bulk is destroyed but finite-sized isotropic fluctuations persist, with a correlation length roughly equal to that of the low-temperature in-plane surface correlation length.
Aad, G.
2015-09-14
Correlations between the elliptic or triangular flow coefficients vm (m=2 or 3) and other flow harmonics vn (n=2 to 5) are measured using √sNN=2.76 TeV Pb+Pb collision data collected in 2010 by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 7 μb-1. The vm-vn correlations are measured in midrapidity as a function of centrality, and, for events within the same centrality interval, as a function of event ellipticity or triangularity defined in a forward rapidity region. For events within the same centrality interval, v3 is found to be anticorrelated with v2 and this anticorrelation is consistentmore » with similar anticorrelations between the corresponding eccentricities, ε2 and ε3. However, it is observed that v4 increases strongly with v2, and v5 increases strongly with both v2 and v3. The trend and strength of the vm-vn correlations for n=4 and 5 are found to disagree with εm-εn correlations predicted by initial-geometry models. Instead, these correlations are found to be consistent with the combined effects of a linear contribution to vn and a nonlinear term that is a function of v22 or of v2v3, as predicted by hydrodynamic models. A simple two-component fit is used to separate these two contributions. The extracted linear and nonlinear contributions to v4 and v5 are found to be consistent with previously measured event-plane correlations.« less
Aad, G.
2015-09-14
Correlations between the elliptic or triangular flow coefficients v_{m} (m=2 or 3) and other flow harmonics v_{n} (n=2 to 5) are measured using √s_{NN}=2.76 TeV Pb+Pb collision data collected in 2010 by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 7 μb^{-1}. The v_{m}-v_{n} correlations are measured in midrapidity as a function of centrality, and, for events within the same centrality interval, as a function of event ellipticity or triangularity defined in a forward rapidity region. For events within the same centrality interval, v_{3} is found to be anticorrelated with v_{2} and this anticorrelation is consistent with similar anticorrelations between the corresponding eccentricities, ε_{2} and ε_{3}. However, it is observed that v_{4} increases strongly with v_{2}, and v_{5} increases strongly with both v_{2} and v_{3}. The trend and strength of the vm-vn correlations for n=4 and 5 are found to disagree with ε_{m}-ε_{n} correlations predicted by initial-geometry models. Instead, these correlations are found to be consistent with the combined effects of a linear contribution to vn and a nonlinear term that is a function of v^{2}_{2} or of v_{2}v_{3}, as predicted by hydrodynamic models. A simple two-component fit is used to separate these two contributions. The extracted linear and nonlinear contributions to v_{4} and v_{5} are found to be consistent with previously measured event-plane correlations.
NASA Astrophysics Data System (ADS)
D'Angelo, Milena; Pepe, Francesco V.; Garuccio, Augusto; Scarcelli, Giuliano
2016-06-01
Plenoptic imaging is a promising optical modality that simultaneously captures the location and the propagation direction of light in order to enable three-dimensional imaging in a single shot. However, in standard plenoptic imaging systems, the maximum spatial and angular resolutions are fundamentally linked; thereby, the maximum achievable depth of field is inversely proportional to the spatial resolution. We propose to take advantage of the second-order correlation properties of light to overcome this fundamental limitation. In this Letter, we demonstrate that the correlation in both momentum and position of chaotic light leads to the enhanced refocusing power of correlation plenoptic imaging with respect to standard plenoptic imaging.
Fischer, P.; Iwasa, K.; Kunii, S.; Kuwahara, K.; Kohgi, M.; Hansen, T.
2005-07-01
By means of powder neutron diffraction investigations, chemical structure and magnetic Ce ordering of Ce{sub 0.75}La{sub 0.25}{sup 11}B{sub 6} have been investigated at temperatures down to 105 mK. In the antiferromagnetic low-temperature phase III Ce{sub 0.75}La{sub 0.25}{sup 11}B{sub 6} resembles pure CeB{sub 6}, but has a lower Neel temperature T{sub N} between 0.89 and 1.25 K. Similar to the recently determined magnetic ordering in pure CeB{sub 6} (model C), one obtains the compared to CeB{sub 6} smaller ordered magnetic Ce moments {mu}{sub Ce(1)}=0.53(1) {mu}{sub B} at z=0 and {mu}{sub Ce(2)}=0.12(1) {mu}{sub B} at z=1/2 with respect to the magnetic unit cell at 105 mK. Presumably this magnetic ordering, which is characterized by both propagation vectors k=[1/4,1/4,0] and k{sup '}=[1/4,1/4,1/2], is caused by competition between magnetic dipole and multipolar ordering. At 0.89 K the magnetic moments are reduced to {mu}{sub Ce(1)}=0.31(1){mu}{sub B} and {mu}{sub Ce(2)}=0.08(1){mu}{sub B}. At 1.25 K in phase IV with presumably multipolar Ce ordering no significant magnetic Bragg peaks associated with magnetic dipole Ce moments were observed, supporting the octupole model of Kubo and Kuramoto for this phase.
Time ordering in atomic collisions
NASA Astrophysics Data System (ADS)
McGuire, J. H.; Godunov, A. L.; Shakov, Kh Kh; Kaplan, L.; Burin, A.; Uskov, D.
2007-06-01
Time ordering constrains interactions to occur in increasing (or decreasing) order. This places a constraint on the time evolution of the system and can lead to correlations in time of different particles in a few/many body system. Unlike overall time reversal, time ordering is not a conserved symmetry of the atomic system. A number of examples of observable effects of time ordering are presented. A convenient way to describe time ordering is to define the limit of no time ordering by replacing the instantaneous interaction by its time average. This is similar to the way in which spatial correlation is defined. Like spatial correlation, time ordering is usually formulated in the interaction representation. The effects of time ordering can differ in different representations. In energy space, conjugate to time space, time ordering is imposed as the i ɛ term in the Greens' function that corresponds to an initial condition (usually incoming plane waves and outgoing scattered waves). This permits off-energy-shell (energy non- conserving) fluctuations during the collision consistent with the Uncertainty Principle.
NASA Technical Reports Server (NTRS)
Cotariu, Steven S.
1991-01-01
Pattern recognition may supplement or replace certain navigational aids on spacecraft in docking or landing activities. The need to correctly identify terrain features remains critical in preparation of autonomous planetary landing. One technique that may solve this problem is optical correlation. Correlation has been successfully demonstrated under ideal conditions; however, noise significantly affects the ability of the correlator to accurately identify input signals. Optical correlation in the presence of noise must be successfully demonstrated before this technology can be incorporated into system design. An optical correlator is designed and constructed using a modified 2f configuration. Liquid crystal televisions (LCTV) are used as the spatial light modulators (SLM) for both the input and filter devices. The filter LCTV is characterized and an operating curve is developed. Determination of this operating curve is critical for reduction of input noise. Correlation of live input with a programmable filter is demonstrated.
Majed, L; Heugas, A-M; Chamon, M; Siegler, I A
2012-12-01
This study investigated how novices learn an energy demanding and biomechanically constrained task like racewalking. The first aim was to examine if movement reorganizes according to some fundamental strategies, proceeding in different stages (Newell, 1985). The second aim was to investigate the link between movement reorganization, metabolic efficiency and perceived exertion. Seven participants undertook seven racewalking learning sessions on a motorized treadmill, with increased velocity as the experiment progressed, in order to reach a goal performance speed of 10 kmh(-1). Peripheral/central perceived exertion ratings, kinematic and metabolic data were collected during the 1st, 4th, 6th and 7th session. Repeated-measures (Learning Session×Speed) ANOVAs on kinematic data showed a proximal-to-distal directional trend in movement reorganization, with significant practice-related changes in pattern coordination and decreased variability. Early movement reorganization occurred at the 1st session ("coordination stage") and progressed until the 4th session ("control stage") to reach a plateau. In contrast, metabolic efficiency and peripheral perceived exertion continued optimizing until the last session, probably occurring in concurrence with the control stage. Peripheral perceived exertion presented the highest correlation with the global movement reorganization variables suggesting that it could play a key role in guiding movement reorganization in the learning process, improving efficiency as a result.
NASA Astrophysics Data System (ADS)
Novakovskaya, O. Yu.; Ushenko, A. G.; Dubolazov, A. V.; Ushenko, V. A.; Ushenko, Yu. A.; Sakhnovskiy, M. Yu.; Soltys, I. V.; Zhytaryuk, V. H.; Olar, O. V.; Sidor, M.; Gorsky, M. P.
2016-12-01
The theoretical background of azimuthally stable method of Jones-matrix mapping of histological sections of biopsy of myocardium tissue on the basis of spatial frequency selection of the mechanisms of linear and circular birefringence is presented. The diagnostic application of a new correlation parameter - complex degree of mutual anisotropy - is analytically substantiated. The method of measuring coordinate distributions of complex degree of mutual anisotropy with further spatial filtration of their high- and low-frequency components is developed. The interconnections of such distributions with parameters of linear and circular birefringence of myocardium tissue histological sections are found. The comparative results of measuring the coordinate distributions of complex degree of mutual anisotropy formed by fibrillar networks of myosin fibrils of myocardium tissue of different necrotic states - dead due to coronary heart disease and acute coronary insufficiency are shown. The values and ranges of change of the statistical (moments of the 1st - 4th order) parameters of complex degree of mutual anisotropy coordinate distributions are studied. The objective criteria of differentiation of cause of death are determined.
Pi Bond Orders and Bond Lengths
ERIC Educational Resources Information Center
Herndon, William C.; Parkanyi, Cyril
1976-01-01
Discusses three methods of correlating bond orders and bond lengths in unsaturated hydrocarbons: the Pauling theory, the Huckel molecular orbital technique, and self-consistent-field techniques. (MLH)
Higher-order uncertainty relations
NASA Astrophysics Data System (ADS)
Wünsche, A.
2006-07-01
Using the non-negativity of Gram determinants of arbitrary order, we derive higher-order uncertainty relations for the symmetric uncertainty matrices of corresponding order n?>?2 to n Hermitean operators (n?=?2 is the usual case). The special cases of third-order and fourth-order uncertainty relations are considered in detail. The obtained third-order uncertainty relations are applied to the Lie groups SU(1,1) with three Hermitean basis operators (K1,K2,K0) and SU(2) with three Hermitean basis operators (J1,J2,J3) where, in particular, the group-coherent states of Perelomov type and of Barut Girardello type for SU(1,1) and the spin or atomic coherent states for SU(2) are investigated. The uncertainty relations for the determinant of the third-order uncertainty matrix are satisfied with the equality sign for coherent states and this determinant becomes vanishing for the Perelomov type of coherent states for SU(1,1) and SU(2). As an example of the application of fourth-order uncertainty relations, we consider the canonical operators (Q1,P1,Q2,P2) of two boson modes and the corresponding uncertainty matrix formed by the operators of the corresponding mean deviations, taking into account the correlations between the two modes. In two mathematical appendices, we prove the non-negativity of the determinant of correlation matrices of arbitrary order and clarify the principal structure of higher-order uncertainty relations.
Hadronic Correlations and Fluctuations
Koch, Volker
2008-10-09
We will provide a review of some of the physics which can be addressed by studying fluctuations and correlations in heavy ion collisions. We will discuss Lattice QCD results on fluctuations and correlations and will put them into context with observables which have been measured in heavy-ion collisions. Special attention will be given to the QCD critical point and the first order co-existence region, and we will discuss how the measurement of fluctuations and correlations can help in an experimental search for non-trivial structures in the QCD phase diagram.
Bao, Junwei Lucas; Odoh, Samuel O; Gagliardi, Laura; Truhlar, Donald G
2017-02-14
We study the performance of multiconfiguration pair-density functional theory (MC-PDFT) and multireference perturbation theory for the computation of the bond dissociation energies in 12 transition-metal-containing diatomic molecules and three small transition-metal-containing polyatomic molecules and in two transition-metal dimers. The first step is a multiconfiguration self-consistent-field calculation, for which two choices must be made: (i) the active space and (ii) its partition into subspaces, if the generalized active space formulation is used. In the present work, the active space is chosen systematically by using three correlated-participating-orbitals (CPO) schemes, and the partition is chosen by using the separated-pair (SP) approximation. Our calculations show that MC-PDFT generally has similar accuracy to CASPT2, and the active-space dependence of MC-PDFT is not very great for transition-metal-ligand bond dissociation energies. We also find that the SP approximation works very well, and in particular SP with the fully translated BLYP functional SP-ftBLYP is more accurate than CASPT2. SP greatly reduces the number of configuration state functions relative to CASSCF. For the cases of FeO and NiO with extended-CPO active space, for which complete active space calculations are unaffordable, SP calculations are not only affordable but also of satisfactory accuracy. All of the MC-PDFT results are significantly better than the corresponding results with broken-symmetry spin-unrestricted Kohn-Sham density functional theory. Finally we test a perturbation theory method based on the SP reference and find that it performs slightly worse than CASPT2 calculations, and for most cases of the nominal-CPO active space, the approximate SP perturbation theory calculations are less accurate than the much less expensive SP-PDFT calculations.
NASA Astrophysics Data System (ADS)
Romano, Francesco; Trifiletti, Alessandro; Cimmino, Rosario F.
2016-07-01
The paper focuses on an innovative spherical wave beam quadratic order processor, HSCS-1. It is an IP, Coulob Gauge based, to directly mesure, ∀t and in any single P ∀P (along the propagation axis too) the quadratic order Poynting Vector, with both the complex Linear Momentum (LiM) and Angolar Momentum (AnM) contributions, as well as the mutual quadratic order coherence function of any total or pseudo monochromatic observed beam wave. The focoused spherical quadratic order method, directly mesure the spherical complex OAM (time and propagation axsis invariant) which is composed by the observed beam wave modes. Such solenoidal energy modes, becomes relevant to mesure far distance (as exemple: distance greater than billions of light years away) sources radiations. Furthermore, HSCS-1 contemporary and directly measure the mutual (spatial as well as temporal) complex coherence of any general complex divergent or not strictly TEM (as example: TEM+DEM) observed radiations. Tipically TEM+DEM radiations are characterized by N=LPM+1 complex wave beam modes. N is the number of considered EM fields modes, as great as requested; N and L are integer, which values are internal to a closed interval [0; ∞] P and M are integer, which values are internal to a closed interval [1; ∞] n=0,1,…,N is the mode or beam channel index; with l=0, 1,…,L; p= 1,…, P; and m = 1,…,M; n=l=0 is the fundamental mode index). Here are considered only the wave beam modes which satisfy the related Helmoltz monochromatic wave equation soluctions. As well known in Physics, only adopting a quadratic order energy processor it is possible ∀t to contemporary and directely mesure in P, ∀P(θ Φ z) and ∀(P-P0), both the proper P0 position and quantity of motion (proper space time variations), or by a Fourier Transformation to contemporary and directely mesure proper phase and frequency spectrum variations, of the observed general radiation source.
Rocket Auroral Correlator Experiment
NASA Technical Reports Server (NTRS)
LaBelle, James
2003-01-01
Dartmouth College provided a multi-channel high- and low- frequency wave receivers, including active sensors on deployable booms, to the Rocket Auroral Correlator Experiment launched from Poker Flat, Alaska, in January 2002. College also performed preliminary analysis of the data. Details are outlined in chronological order.
Burnett, T. L.; McDonald, S. A.; Gholinia, A.; Geurts, R.; Janus, M.; Slater, T.; Haigh, S. J.; Ornek, C.; Almuaili, F.; Engelberg, D. L.; Thompson, G. E.; Withers, P. J.
2014-01-01
Increasingly researchers are looking to bring together perspectives across multiple scales, or to combine insights from different techniques, for the same region of interest. To this end, correlative microscopy has already yielded substantial new insights in two dimensions (2D). Here we develop correlative tomography where the correlative task is somewhat more challenging because the volume of interest is typically hidden beneath the sample surface. We have threaded together x-ray computed tomography, serial section FIB-SEM tomography, electron backscatter diffraction and finally TEM elemental analysis all for the same 3D region. This has allowed observation of the competition between pitting corrosion and intergranular corrosion at multiple scales revealing the structural hierarchy, crystallography and chemistry of veiled corrosion pits in stainless steel. With automated correlative workflows and co-visualization of the multi-scale or multi-modal datasets the technique promises to provide insights across biological, geological and materials science that are impossible using either individual or multiple uncorrelated techniques. PMID:24736640
Localization protected quantum order
NASA Astrophysics Data System (ADS)
Nandkishore, Rahul
2015-03-01
Many body localization occurs in isolated quantum systems, usually with strong disorder, and is marked by absence of dissipation, absence of thermal equilibration, and a memory of the initial conditions that survives in local observables for arbitrarily long times. The many body localized regime is a non-equilibrium, strongly disordered, non-self averaging regime that presents a new frontier for quantum statistical mechanics. In this talk, I point out that there exists a vast zoo of correlated many body localized states of matter, which may be classified using familiar notions of spontaneous symmetry breaking and topological order. I will point out that in the many body localized regime, spontaneous symmetry breaking can occur even at high energy densities in one dimensional systems, and topological order can occur even without a bulk gap. I will also discuss the phenomenology of imperfectly isolated many body localized systems, which are weakly coupled to a heat bath. I will conclude with a brief discussion of how these phenomena may best be detected in experiments. Collaborators: David Huse, S.L. Sondhi, Arijeet Pal, Vadim Oganesyan, A.C. Potter, Sarang Gopalakrishnan, S. Johri, R.N. Bhatt.
Variable Order and Distributed Order Fractional Operators
NASA Technical Reports Server (NTRS)
Lorenzo, Carl F.; Hartley, Tom T.
2002-01-01
Many physical processes appear to exhibit fractional order behavior that may vary with time or space. The continuum of order in the fractional calculus allows the order of the fractional operator to be considered as a variable. This paper develops the concept of variable and distributed order fractional operators. Definitions based on the Riemann-Liouville definitions are introduced and behavior of the operators is studied. Several time domain definitions that assign different arguments to the order q in the Riemann-Liouville definition are introduced. For each of these definitions various characteristics are determined. These include: time invariance of the operator, operator initialization, physical realization, linearity, operational transforms. and memory characteristics of the defining kernels. A measure (m2) for memory retentiveness of the order history is introduced. A generalized linear argument for the order q allows the concept of "tailored" variable order fractional operators whose a, memory may be chosen for a particular application. Memory retentiveness (m2) and order dynamic behavior are investigated and applications are shown. The concept of distributed order operators where the order of the time based operator depends on an additional independent (spatial) variable is also forwarded. Several definitions and their Laplace transforms are developed, analysis methods with these operators are demonstrated, and examples shown. Finally operators of multivariable and distributed order are defined in their various applications are outlined.
Area correlation in transform domain
NASA Astrophysics Data System (ADS)
Merchant, S. N.; Rao, B. V.
1983-10-01
It has been shown that the optimal test statistic in the Neyman-Pearson sense for area correlation is the modified correlation coefficient. In order to reduce the heavy computational burden of such an optimal scheme, a sub-optimal scheme based on the utilization of linear transformations has been investigated. Feature selection based on the entropy concept, and through K-L expansion has also been investigated in area correlation applications through a simulation study.
Loussert Fonta, Céline; Humbel, Bruno M
2015-09-01
In recent years correlative microscopy, combining the power and advantages of different imaging system, e.g., light, electrons, X-ray, NMR, etc., has become an important tool for biomedical research. Among all the possible combinations of techniques, light and electron microscopy, have made an especially big step forward and are being implemented in more and more research labs. Electron microscopy profits from the high spatial resolution, the direct recognition of the cellular ultrastructure and identification of the organelles. It, however, has two severe limitations: the restricted field of view and the fact that no live imaging can be done. On the other hand light microscopy has the advantage of live imaging, following a fluorescently tagged molecule in real time and at lower magnifications the large field of view facilitates the identification and location of sparse individual cells in a large context, e.g., tissue. The combination of these two imaging techniques appears to be a valuable approach to dissect biological events at a submicrometer level. Light microscopy can be used to follow a labelled protein of interest, or a visible organelle such as mitochondria, in time, then the sample is fixed and the exactly same region is investigated by electron microscopy. The time resolution is dependent on the speed of penetration and fixation when chemical fixatives are used and on the reaction time of the operator for cryo-fixation. Light microscopy can also be used to identify cells of interest, e.g., a special cell type in tissue or cells that have been modified by either transfections or RNAi, in a large population of non-modified cells. A further application is to find fluorescence labels in cells on a large section to reduce searching time in the electron microscope. Multiple fluorescence labelling of a series of sections can be correlated with the ultrastructure of the individual sections to get 3D information of the distribution of the marked proteins: array
NASA Astrophysics Data System (ADS)
Ungurian, V. P.; Ivashchuk, O. I.; Ushenko, V. O.
2012-01-01
This work is aimed at searching the interconnections between the statistic structure of blood plasma microscopic images and manifestations of optical anisotropy of liquid crystal protein network. The model of linear birefringence of albumin and globulin crystals underlies in the ground of this work. The results of investigating the interrelation between statistical moments of the 1st-4th order are presented that characterize the coordinate distributions of polarization ellipticity of laser images of blood plasma smears and pathological changes in human organism. The diagnostic criteria of breast cancer nascency and its severity degree differentiation are determined.
NASA Astrophysics Data System (ADS)
Ushenko, Yu. O.; Dubolazov, O. V.; Olar, O. V.
2015-11-01
The theoretical background of azimuthally stable method Jones matrix mapping of histological sections of biopsy of uterine neck on the basis of spatial-frequency selection of the mechanisms of linear and circular birefringence is presented. The comparative results of measuring the coordinate distributions of complex degree of mutual anisotropy formed by polycristalline networks of blood plasma layers of donors (group 1) and patients with endometriosis (group 2). The values and ranges of change of the statistical (moments of the 1st - 4th order) parameters of complex degree of mutual anisotropy coordinate distributions are studied. The objective criteria of diagnostics of the pathology and differentiation of its severity degree are determined.
NASA Astrophysics Data System (ADS)
Ushenko, O. G.; Koval, L. D.; Dubolazov, O. V.; Ushenko, Yu. O.; Savich, V. O.; Sidor, M. I.; Marchuk, Yu. F.
2015-09-01
The theoretical background of azimuthally stable method Jones matrix mapping of histological sections of biopsy of uterine neck on the basis of spatial-frequency selection of the mechanisms of linear and circular birefringence is presented. The comparative results of measuring the coordinate distributions of complex degree of mutual anisotropy formed by polycristalline networks of blood plasma layers of donors (group 1) and patients with endometriosis (group 2). The values and ranges of change of the statistical (moments of the 1st - 4th order) parameters of complex degree of mutual anisotropy coordinate distributions are studied. The objective criteria of diagnostics of the pathology and differentiation of its severity degree are determined.
Laser statistical polarimetry optical anisotropy of blood plasma of the patients with hemangioma
NASA Astrophysics Data System (ADS)
Boychuk, T. M.; Bodnar, B. M.; Vatamanesku, L. I.
2012-01-01
Proposed in this work is a novel method of early laser polarimetric diagnostics of vessels pathologies and hemangioma formation. The generalized model of formation processes of polarization inhomogeneous laser images of experimental samples of biological tissues is presented. It was performed the experimental measurements of polarization states of both biological tissues laser images points and the hemangioma liquids. The results of investigating the interrelation between statistical moments of the 1st-4th order are presented that characterize the coordinate distributions of polarization azimuth of laser images of histological sections of hemangioma, hemangioma blood smears and blood plasma with vascular system pathologies. The diagnostic criteria of hemangioma nascency are determined.
Laser statistical polarimetry optical anisotropy of blood plasma of the patients with hemangioma
NASA Astrophysics Data System (ADS)
Boychuk, T. M.; Bodnar, B. M.; Vatamanesku, L. I.
2011-09-01
Proposed in this work is a novel method of early laser polarimetric diagnostics of vessels pathologies and hemangioma formation. The generalized model of formation processes of polarization inhomogeneous laser images of experimental samples of biological tissues is presented. It was performed the experimental measurements of polarization states of both biological tissues laser images points and the hemangioma liquids. The results of investigating the interrelation between statistical moments of the 1st-4th order are presented that characterize the coordinate distributions of polarization azimuth of laser images of histological sections of hemangioma, hemangioma blood smears and blood plasma with vascular system pathologies. The diagnostic criteria of hemangioma nascency are determined.
Strongly correlated materials.
Morosan, Emilia; Natelson, Douglas; Nevidomskyy, Andriy H; Si, Qimiao
2012-09-18
Strongly correlated materials are profoundly affected by the repulsive electron-electron interaction. This stands in contrast to many commonly used materials such as silicon and aluminum, whose properties are comparatively unaffected by the Coulomb repulsion. Correlated materials often have remarkable properties and transitions between distinct, competing phases with dramatically different electronic and magnetic orders. These rich phenomena are fascinating from the basic science perspective and offer possibilities for technological applications. This article looks at these materials through the lens of research performed at Rice University. Topics examined include: Quantum phase transitions and quantum criticality in "heavy fermion" materials and the iron pnictide high temperature superconductors; computational ab initio methods to examine strongly correlated materials and their interface with analytical theory techniques; layered dichalcogenides as example correlated materials with rich phases (charge density waves, superconductivity, hard ferromagnetism) that may be tuned by composition, pressure, and magnetic field; and nanostructure methods applied to the correlated oxides VO₂ and Fe₃O₄, where metal-insulator transitions can be manipulated by doping at the nanoscale or driving the system out of equilibrium. We conclude with a discussion of the exciting prospects for this class of materials.
Constructing higher-order hydrodynamics: The third order
NASA Astrophysics Data System (ADS)
Grozdanov, Sašo; Kaplis, Nikolaos
2016-03-01
Hydrodynamics can be formulated as the gradient expansion of conserved currents in terms of the fundamental fields describing the near-equilibrium fluid flow. In the relativistic case, the Navier-Stokes equations follow from the conservation of the stress-energy tensor to first order in derivatives. In this paper, we go beyond the presently understood second-order hydrodynamics and discuss the systematization of obtaining the hydrodynamic expansion to an arbitrarily high order. As an example of the algorithm that we present, we fully classify the gradient expansion at third order for neutral fluids in four dimensions, thus finding the most general next-to-leading-order corrections to the relativistic Navier-Stokes equations in curved space-time. In doing so, we list 20 new transport coefficient candidates in the conformal case and 68 in the nonconformal case. As we do not consider any constraints that could potentially arise from the local entropy current analysis, this is the maximal possible set of neutral third-order transport coefficients. To investigate the physical implications of these new transport coefficients, we obtain the third-order corrections to the linear dispersion relations that describe the propagation of diffusion and sound waves in relativistic fluids. We also compute the corrections to the scalar (spin-2) two-point correlation function of the third-order stress-energy tensor. Furthermore, as an example of a nonlinear hydrodynamic flow, we calculate the third-order corrections to the energy density of a boost-invariant Bjorken flow. Finally, we apply our field theoretic results to the N =4 supersymmetric Yang-Mills fluid at infinite 't Hooft coupling and an infinite number of colors to find the values of five new linear combinations of the conformal transport coefficients.
Correlations of correlations: Secondary autocorrelations in finite harmonic systems.
Plyukhin, Dan; Plyukhin, Alex V
2015-10-01
The momentum or velocity autocorrelation function C(t) for a tagged oscillator in a finite harmonic system decays like that of an infinite system for short times, but exhibits erratic behavior at longer time scales. We introduce the autocorrelation function of the long-time noisy tail of C(t) ("a correlation of the correlation"), which characterizes the distribution of recurrence times. Remarkably, for harmonic systems with same-mass particles this secondary correlation may coincide with the primary correlation C(t) (when both functions are normalized) either exactly, or over a significant initial time interval. When the tagged particle is heavier than the rest, the equality does not hold, correlations show nonrandom long-time scale pattern, and higher-order correlations converge to the lowest normal mode.
Order Theoretical Semantic Recommendation
Joslyn, Cliff A.; Hogan, Emilie A.; Paulson, Patrick R.; Peterson, Elena S.; Stephan, Eric G.; Thomas, Dennis G.
2013-07-23
Mathematical concepts of order and ordering relations play multiple roles in semantic technologies. Discrete totally ordered data characterize both input streams and top-k rank-ordered recommendations and query output, while temporal attributes establish numerical total orders, either over time points or in the more complex case of startend temporal intervals. But also of note are the fully partially ordered data, including both lattices and non-lattices, which actually dominate the semantic strcuture of ontological systems. Scalar semantic similarities over partially-ordered semantic data are traditionally used to return rank-ordered recommendations, but these require complementation with true metrics available over partially ordered sets. In this paper we report on our work in the foundations of partial order measurement in ontologies, with application to top-k semantic recommendation in workflows.
Peyton, B.W.
1999-07-01
When minimum orderings proved too difficult to deal with, Rose, Tarjan, and Leuker instead studied minimal orderings and how to compute them (Algorithmic aspects of vertex elimination on graphs, SIAM J. Comput., 5:266-283, 1976). This paper introduces an algorithm that is capable of computing much better minimal orderings much more efficiently than the algorithm in Rose et al. The new insight is a way to use certain structures and concepts from modern sparse Cholesky solvers to re-express one of the basic results in Rose et al. The new algorithm begins with any initial ordering and then refines it until a minimal ordering is obtained. it is simple to obtain high-quality low-cost minimal orderings by using fill-reducing heuristic orderings as initial orderings for the algorithm. We examine several such initial orderings in some detail.
Kolb, E.W. Chicago Univ., IL . Enrico Fermi Inst.)
1990-09-01
In the original proposal, inflation occurred in the process of a strongly first-order phase transition. This model was soon demonstrated to be fatally flawed. Subsequent models for inflation involved phase transitions that were second-order, or perhaps weakly first-order; some even involved no phase transition at all. Recently the possibility of inflation during a strongly first-order phase transition has been revived. In this talk I will discuss some models for first-order inflation, and emphasize unique signatures that result in inflation is realized in a first-order transition. Before discussing first-order inflation, I will briefly review some of the history of inflation to demonstrate how first-order inflation differs from other models. 58 refs., 3 figs.
Atmospheric Science Data Center
2017-02-08
... Ordering requires login , searching does not. Projects by science discipline: Aerosols | Clouds | Radiation Budget ... Tropospheric Composition | Field Campaigns All projects Details: ASDC Ordering Tool ...
Two-dimensional order and disorder thermofields
Belvedere, L. V.
2006-11-15
The main objective of this paper was to obtain the two-dimensional order and disorder thermal operators using the Thermofield Bosonization formalism. We show that the general property of the two-dimensional world according with the bosonized Fermi field at zero temperature can be constructed as a product of an order and a disorder variables which satisfy a dual field algebra holds at finite temperature. The general correlation functions of the order and disorder thermofields are obtained.
Glassy correlations in nematic elastomers
NASA Astrophysics Data System (ADS)
Lu, Bing; Goldbart, Paul; Mao, Xiaoming
2009-03-01
We address the physical properties of an isotropic melt or solution of nematogenic polymers that is then cross-linked beyond the vulcanization point. To do this, we construct a replica Landau theory involving a coupled pair of order- parameter fields: one describing vulcanization, the other describing local nematic order. Thermal nematic fluctuations, present at the time of cross-linking, are trapped by cross- linking into the vulcanized network. The resulting glassy nematic fluctuations are analyzed in the Gaussian approximation in two regimes. When the localization length is shorter than the thermal nematic correlation length, the nematic correlations are well captured as glassy correlations. In the opposite regime, fluctuations in the positions of the localized polymers partially wash out the glassy nematic correlations.
Local realism of macroscopic correlations.
Ramanathan, R; Paterek, T; Kay, A; Kurzyński, P; Kaszlikowski, D
2011-08-05
We identify conditions under which correlations resulting from quantum measurements performed on macroscopic systems (systems composed of a number of particles of the order of the Avogadro number) can be described by local realism. We argue that the emergence of local realism at the macroscopic level is caused by an interplay between the monogamous nature of quantum correlations and the fact that macroscopic measurements do not reveal properties of individual particles.
Local Realism of Macroscopic Correlations
NASA Astrophysics Data System (ADS)
Ramanathan, R.; Paterek, T.; Kay, A.; Kurzyński, P.; Kaszlikowski, D.
2011-08-01
We identify conditions under which correlations resulting from quantum measurements performed on macroscopic systems (systems composed of a number of particles of the order of the Avogadro number) can be described by local realism. We argue that the emergence of local realism at the macroscopic level is caused by an interplay between the monogamous nature of quantum correlations and the fact that macroscopic measurements do not reveal properties of individual particles.
Energy Ordering of Molecular Orbitals
2016-01-01
Orbitals are invaluable in providing a model of bonding in molecules or between molecules and surfaces. Most present-day methods in computational chemistry begin by calculating the molecular orbitals of the system. To what extent have these mathematical objects analogues in the real world? To shed light on this intriguing question, we employ a photoemission tomography study on monolayers of 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) grown on three Ag surfaces. The characteristic photoelectron angular distribution enables us to assign individual molecular orbitals to the emission features. When comparing the resulting energy positions to density functional calculations, we observe deviations in the energy ordering. By performing complete active space calculations (CASSCF), we can explain the experimentally observed orbital ordering, suggesting the importance of static electron correlation beyond a (semi)local approximation. On the other hand, our results also show reality and robustness of the orbital concept, thereby making molecular orbitals accessible to experimental observations. PMID:27935313
Variable angle correlation spectroscopy
Lee, Young Kyo
1994-05-01
In this dissertation, a novel nuclear magnetic resonance (NMR) technique, variable angle correlation spectroscopy (VACSY) is described and demonstrated with ^{13}C nuclei in rapidly rotating samples. These experiments focus on one of the basic problems in solid state NMR: how to extract the wealth of information contained in the anisotropic component of the NMR signal while still maintaining spectral resolution. Analysis of the anisotropic spectral patterns from poly-crystalline systems reveal information concerning molecular structure and dynamics, yet in all but the simplest of systems, the overlap of spectral patterns from chemically distinct sites renders the spectral analysis difficult if not impossible. One solution to this problem is to perform multi-dimensional experiments where the high-resolution, isotropic spectrum in one dimension is correlated with the anisotropic spectral patterns in the other dimensions. The VACSY technique incorporates the angle between the spinner axis and the static magnetic field as an experimental parameter that may be incremented during the course of the experiment to help correlate the isotropic and anisotropic components of the spectrum. The two-dimensional version of the VACSY experiments is used to extract the chemical shift anisotropy tensor values from multi-site organic molecules, study molecular dynamics in the intermediate time regime, and to examine the ordering properties of partially oriented samples. The VACSY technique is then extended to three-dimensional experiments to study slow molecular reorientations in a multi-site polymer system.
Characterizing limit order prices
NASA Astrophysics Data System (ADS)
Withanawasam, R. M.; Whigham, P. A.; Crack, Timothy Falcon
2013-11-01
A computational model of a limit order book is used to study the effect of different limit order distribution offsets. Reference prices such as same side/contra side best market prices and last traded price are considered in combination with different price offset distributions. We show that when characterizing limit order prices, varying the offset distribution only produces different behavior when the reference price is the contra side best price. Irrespective of the underlying mechanisms used in computing the limit order prices, the shape of the price graph and the behavior of the average order book profile distribution are strikingly similar in all the considered reference prices/offset distributions. This implies that existing averaging methods can cancel variabilities in limit order book shape/attributes and may be misleading.
Multiple ordering in magnetite.
NASA Technical Reports Server (NTRS)
Cullen, J. R.; Callen, E. R.
1973-01-01
Results of a self-consistent band calculation of the ground-state energy and charge orderings based on a tight-binding scheme in magnetite are presented. They show that below a critical (about 2.2) value of the ratio of interatomic Coulomb energy to bandwidth the lowest energy state has no order. Between this critical value and 2.5, the preferred state is multiply ordered.
Selective correlations; not voodoo.
Rosenblatt, J D; Benjamini, Y
2014-12-01
The problem of "voodoo" correlations-exceptionally high observed correlations in selected regions of the brain-is well recognized in neuroimaging. It arises when quantities of interest are estimated from the same data that was used to select them as interesting. In statistical terminology, the problem of inference following selection from the same data is that of selective inference. Motivated by the unwelcome side-effects of splitting the data- the recommended remedy-we adapt the recent developments in selective inference in order to construct confidence intervals (CIs) with good reproducibility prospects, even if selection and estimation are done with the same data. These intervals control the expected proportion of non-covered correlations in the selected voxels-the False Coverage Rate (FCR). They extend further toward zero than standard intervals, thus attenuating the impression made by highly biased observed correlations. They do so adaptively, in that they coincide with the standard CIs when far away from the selection point. We complement existing analytic proofs with a simulation, showing that the proposed intervals control the FCR in realistic social neuroscience problems. We also suggest a "confidence calibration plot", to allow the intervals to be reported in a clear and interpretable way. Applying the proposed methodology on a loss-aversion study, we demonstrate that with the sample size and selection type employed, selection bias is considerable. Finally, selective intervals are compared to the currently recommended data-splitting approach. We discover that our approach has more power and typically more informative, as no data is discarded. Computation of the intervals is implemented in an accompanying software package.
Eyring, W E; Sobelman, S
1996-04-01
The purpose of this investigation was to clarify the relationship between birth-order position and the development of narcissism, while refining research and theory. The relationship between birth-order status and narcissism was examined with a sample of 79 undergraduate students (55 women and 24 men). These subjects were placed in one of the four following birth-order categories of firstborn, second-born, last-born, and only children. These categories were chosen given their significance in Adlerian theory. Each subject completed the Narcissistic Personality Inventory and a demographic inventory. Based on psychodynamic theory, it was hypothesized that firstborn children were expected to score highest, but statistical significance was not found for an association between narcissism and birth order. Further research is urged to investigate personality theory as it relates to parenting style and birth order.
Verb Position and the Order of Adverbials in German.
ERIC Educational Resources Information Center
Dean, O. C., Jr.
Recent work in word-order typology has demonstrated that the dominant order of verbs and objects (or complements) correlates well with the general ordering tendencies of languages. The work on German reported in this paper suggests, however, that certain traits, such as the order of adverbials, are influenced not only by general ordering…
Atmospheric Science Data Center
2012-04-17
... users to search our data holdings without logging in to the system. The user, however, must log in before ordering the data. ... Cavity Radiometer Irradiance Monitor II (ACRIM II) Total Solar Irradiance Data Global Tropospheric Experiment (GTE) data (Selected ...
ERIC Educational Resources Information Center
Reber, Sarah J.
2005-01-01
The effect of the court ordered desegregation plans, on trends in segregation and white flight, are estimated. The effect of availability of school districts and other factors on the white flight across districts is also mentioned.
Ordered macromolecular structures in ferrofluid mixtures
Hayter, J.B.; Pynn, R.; Charles, S.; Skjeltorp, A.T.; Trewhella, J.; Stubbs, G.; Timmins, P.
1989-04-03
We have observed ordering of dilute dispersions of spherical and cylindrical macromolecules in magnetized ferrofluids. The order results from structural correlations between macromolecular and ferrofluid particles rather than from macroscopic magnetostatic effects. We have aligned elongated macromolecules by this technique and have obtained anisotropic neutron-diffraction patterns, which reflect the internal structure of the macromolecules. The method provides a tool for orienting suspended macromolecular assemblies which are not amenable to conventional alignment techniques.
Correlation dynamics of Green functions
NASA Astrophysics Data System (ADS)
Shun-Jin, Wang; Wei, Zuo; Wolfgang, Cassing
1994-06-01
We generalize the methods used in the theory of correlation dynamics and establish a set of equations of motion for many-body correlation Green functions in the nonrelativistic case. These nonlinear and coupled equations of motion describe the dynamical evolution of correlation Green functions of different order and transparently show how many-body correlations are generated by the different interaction terms in a genuine nonperturbative framework. The nonperturbative results of the conventional Green function theory are included in the present formalism as two limiting cases (the so-called ladder-diagram summation and ring-diagram summation) as well as the familiar correlation dynamics of density matrices in the equal-time limit. We present explicit expressions for three- and four-body correlation functions that can be used to dynamically restore the trace relations for spin-symmetric Fermi systems and study numerically the relative importance of two-, three- and four-body correlations for nuclear configurations close to the ground state.
Asymmetric magnon excitation by spontaneous toroidal ordering
Hayami, Satoru; Kusunose, Hiroaki; Motome, Yukitoshi
2016-04-12
The effects of spontaneous toroidal ordering on magnetic excitation are theoretically investigated for a localized spin model that includes a staggered Dzyaloshinsky–Moriya interaction and anisotropic exchange interactions, which arise from the antisymmetric spin–orbit coupling and the multiorbital correlation effect. We show that the model exhibits a Néel-type antiferromagnetic order, which simultaneously accompanies a ferroic toroidal order. We find that the occurrence of toroidal order modulates the magnon dispersion in an asymmetric way with respect to the wave number: a toroidal dipole order on the zigzag chain leads to a band-bottom shift, while a toroidal octupole order on the honeycomb lattice gives rise to a valley splitting. These asymmetric magnon excitations could be a source of unusual magnetic responses, such as nonreciprocal magnon transport. A variety of modulations are discussed while changing the lattice and magnetic symmetries. Furthermore, the implications regarding candidate materials for asymmetric magnon excitations are presented.
Arguments from Developmental Order
Stöckle-Schobel, Richard
2016-01-01
In this article1, I investigate a special type of argument regarding the role of development in theorizing about psychological processes and cognitive capacities. Among the issues that developmental psychologists study, discovering the ontogenetic trajectory of mechanisms or capacities underpinning our cognitive functions ranks highly. The order in which functions are developed or capacities are acquired is a matter of debate between competing psychological theories, and also philosophical conceptions of the mind – getting the role and the significance of the different steps in this order right could be seen as an important virtue of such theories. Thus, a special kind of strategy in arguments between competing philosophical or psychological theories is using developmental order in arguing for or against a given psychological claim. In this article, I will introduce an analysis of arguments from developmental order, which come in two general types: arguments emphasizing the importance of the early cognitive processes and arguments emphasizing the late cognitive processes. I will discuss their role in one of the central tools for evaluating scientific theories, namely in making inferences to the best explanation. I will argue that appeal to developmental order is, by itself, an insufficient criterion for theory choice and has to be part of an argument based on other core explanatory or empirical virtues. I will end by proposing a more concerted study of philosophical issues concerning (cognitive) development, and I will present some topics that also pertain to a full-fledged ‘philosophy of development.’ PMID:27242648
Concomitant Ordering and Symmetry Lowering
ERIC Educational Resources Information Center
Boo, William O. J.; Mattern, Daniell L.
2008-01-01
Examples of concomitant ordering include magnetic ordering, Jahn-Teller cooperative ordering, electronic ordering, ionic ordering, and ordering of partially-filled sites. Concomitant ordering sets in when a crystal is cooled and always lowers the degree of symmetry of the crystal. Concomitant ordering concepts can also be productively applied to…
Wood, Jo; Dykes, Jason
2008-01-01
Existing treemap layout algorithms suffer to some extent from poor or inconsistent mappings between data order and visual ordering in their representation, reducing their cognitive plausibility. While attempts have been made to quantify this mismatch, and algorithms proposed to minimize inconsistency, solutions provided tend to concentrate on one-dimensional ordering. We propose extensions to the existing squarified layout algorithm that exploit the two-dimensional arrangement of treemap nodes more effectively. Our proposed spatial squarified layout algorithm provides a more consistent arrangement of nodes while maintaining low aspect ratios. It is suitable for the arrangement of data with a geographic component and can be used to create tessellated cartograms for geovisualization. Locational consistency is measured and visualized and a number of layout algorithms are compared. CIELab color space and displacement vector overlays are used to assess and emphasize the spatial layout of treemap nodes. A case study involving locations of tagged photographs in the Flickr database is described.
Ying, Alan
2003-01-01
Because both computerized physician order entry (CPOE) systems and mobile technologies such as handheld devices have the potential to greatly impact the industry's future, IT vendors, hospitals, and clinicians are simply merging them into a logical convergence--"CPOE on a handheld"--with an expectation of full functionality on all platforms: computer workstations, rolling laptops, tablet PCs, and handheld devices. For these trends to succeed together, however, this expectation must be revised to establish a distinct category--mobile physician order entry (MPOE)--that is different from CPOE in form, function, and implementation.
Higher order turbulence closure models
NASA Technical Reports Server (NTRS)
Amano, Ryoichi S.; Chai, John C.; Chen, Jau-Der
1988-01-01
Theoretical models are developed and numerical studies conducted on various types of flows including both elliptic and parabolic. The purpose of this study is to find better higher order closure models for the computations of complex flows. This report summarizes three new achievements: (1) completion of the Reynolds-stress closure by developing a new pressure-strain correlation; (2) development of a parabolic code to compute jets and wakes; and, (3) application to a flow through a 180 deg turnaround duct by adopting a boundary fitted coordinate system. In the above mentioned models near-wall models are developed for pressure-strain correlation and third-moment, and incorporated into the transport equations. This addition improved the results considerably and is recommended for future computations. A new parabolic code to solve shear flows without coordinate tranformations is developed and incorporated in this study. This code uses the structure of the finite volume method to solve the governing equations implicitly. The code was validated with the experimental results available in the literature.
Solar wind correlations: Statistical and case studies
NASA Astrophysics Data System (ADS)
Paularena, K. I.; Richardson, J. D.; Zastenker, G. N.; Dalin, P. A.
1999-06-01
Recent work on solar wind plasma correlations using data from several widely-separated spacecraft (IMP 8, INTERBALL-1, WIND, and ISEE-3) has shown that, for 6-hour periods, the average plasma correlation is ~0.7. The focus of these studies has been directed toward a statistical understanding of gross solar wind correlation behavior. In all correlations examined, lower average correlations are caused by the presence of many points from the low correlation subpopulation; nevertheless, data points from the high correlation population are still present. No single organizational factor has yet been found which adequately separates low-correlation periods from high-correlation periods. Some of the spread in correlations is due to the spatial orientations and dimensions of solar wind structures, and thus to the locational alignments of the spacecraft being correlated, but this does not adequately explain all the good or poor correlations since sometimes three nearby spacecraft show poor correlations, while sometimes three widely-separated space-craft show good correlations. Thus, in order to understand the underlying physics, detailed investigation of individual cases has been undertaken. These results will be important in assigning quality measures to space weather predictions using satellite measurements taken at L1, for example.
Spin Dynamics in an Ordered Stripe Phase
NASA Astrophysics Data System (ADS)
Tranquada, J. M.; Wochner, P.; Buttrey, D. J.
1997-09-01
Inelastic neutron scattering has been used to measure the low-energy spin excitations in the ordered charge-stripe phase of La2NiO4+δ with δ = 0.133. Spin-wave-like excitations disperse away from the incommensurate magnetic superlattice points with a velocity ~60% of that in the δ = 0 compound. Incommensurate inelastic peaks remain well resolved up to at least twice the magnetic ordering temperature. Paramagnetic scattering from a δ = 0.105 sample, which has a Néel-ordered ground state, shows anomalies suggestive of incipient stripe correlations. Similarities between these results and measurements on superconducting cuprates are discussed.
Prochaska, Elizabeth; Lomri, Sara
2014-11-01
Court-ordered caesarean sections are in the news after a number of recent legal decisions authorising surgery for women who lack mental capacity to consent. The decisions have not always been based on good evidence and they raise serious concerns about the protection of the rights of mentally ill women. The authors explain the legal process and question the wisdom of recent judgements.
ERIC Educational Resources Information Center
Mische, Patricia, Ed.; And Others
1982-01-01
The papers in this publication discuss the land and how what happens to the land affects us. The publication is one in a series of monographs that examine the linkages between local and global concerns and explore alternative world futures. Examples of topics discussed in the papers follow. The paper "Land and World Order" examines…
ERIC Educational Resources Information Center
Jones, Phillip W.
2007-01-01
The impact on educational analysis of mainstream international relations (IR) theories is yet to realize its full potential. The problem of education in relation to the construction of world order is considered in relation to core developments in IR theory since the Second World War. In particular, the global architecture of education is seen as a…
ERIC Educational Resources Information Center
Zajonc, R. B.
2001-01-01
Critiques Rodgers et al.'s June 2000 research on the relation between birth order and intelligence, which suggests that it is a methodological illusion. Explains how the intellectual environment and the teaching function (whereby older children tutor younger ones) contribute to the growth of intellectual maturity, the first negatively and the…
ERIC Educational Resources Information Center
Zajonc, R. B.; And Others
1979-01-01
Discusses the controversy of the relationship between birth order and intellectual performance through a detailed evaluation of the confluence model which assumes that the rate of intellectual growth is a function of the intellectual environment within the family and associated with the special circumstances of last children. (CM)
Pansedik: Ordering Creative Chaos.
ERIC Educational Resources Information Center
Austin, Barbara L.
1998-01-01
Presents a case study for use in business communication classes to help students understand and learn both the context and the strategies for communication with business and management. Deals with a new human resource director's attempt to bring order to an organization and software developers' concerns over their work being hindered. Includes two…
Order Division Automated System.
ERIC Educational Resources Information Center
Kniemeyer, Justin M.; And Others
This publication was prepared by the Order Division Automation Project staff to fulfill the Library of Congress' requirement to document all automation efforts. The report was originally intended for internal use only and not for distribution outside the Library. It is now felt that the library community at-large may have an interest in the…
Order Lepidoptera Linnaeus, 1758.
Technology Transfer Automated Retrieval System (TEKTRAN)
Based on two recent molecular analyses, augmented by the discovery of several published or unpublished novel morphological synapomorphies, a new classification is proposed for the order Lepidoptera. The new classification is more consistent with our growing knowledge of the phylogeny of the group an...
Order, topology and preference
NASA Technical Reports Server (NTRS)
Sertel, M. R.
1971-01-01
Some standard order-related and topological notions, facts, and methods are brought to bear on central topics in the theory of preference and the theory of optimization. Consequences of connectivity are considered, especially from the viewpoint of normally preordered spaces. Examples are given showing how the theory of preference, or utility theory, can be applied to social analysis.
NASA Astrophysics Data System (ADS)
Thibes, Ronaldo
2017-02-01
We perform the canonical and path integral quantizations of a lower-order derivatives model describing Podolsky's generalized electrodynamics. The physical content of the model shows an auxiliary massive vector field coupled to the usual electromagnetic field. The equivalence with Podolsky's original model is studied at classical and quantum levels. Concerning the dynamical time evolution, we obtain a theory with two first-class and two second-class constraints in phase space. We calculate explicitly the corresponding Dirac brackets involving both vector fields. We use the Senjanovic procedure to implement the second-class constraints and the Batalin-Fradkin-Vilkovisky path integral quantization scheme to deal with the symmetries generated by the first-class constraints. The physical interpretation of the results turns out to be simpler due to the reduced derivatives order permeating the equations of motion, Dirac brackets and effective action.
Hierarchical partial order ranking.
Carlsen, Lars
2008-09-01
Assessing the potential impact on environmental and human health from the production and use of chemicals or from polluted sites involves a multi-criteria evaluation scheme. A priori several parameters are to address, e.g., production tonnage, specific release scenarios, geographical and site-specific factors in addition to various substance dependent parameters. Further socio-economic factors may be taken into consideration. The number of parameters to be included may well appear to be prohibitive for developing a sensible model. The study introduces hierarchical partial order ranking (HPOR) that remedies this problem. By HPOR the original parameters are initially grouped based on their mutual connection and a set of meta-descriptors is derived representing the ranking corresponding to the single groups of descriptors, respectively. A second partial order ranking is carried out based on the meta-descriptors, the final ranking being disclosed though average ranks. An illustrative example on the prioritization of polluted sites is given.
Cuzinatto, R.R. . E-mail: rodrigo@ift.unesp.br; Melo, C.A.M. de . E-mail: cassius.anderson@gmail.com; Pompeia, P.J. . E-mail: pompeia@ift.unesp.br
2007-05-15
A gauge theory of second order in the derivatives of the auxiliary field is constructed following Utiyama's program. A novel field strength G = {partial_derivative}F + fAF arises besides the one of the first order treatment, F = {partial_derivative}A - {partial_derivative}A + fAA. The associated conserved current is obtained. It has a new feature: topological terms are determined from local invariance requirements. Podolsky Generalized Eletrodynamics is derived as a particular case in which the Lagrangian of the gauge field is L {sub P} {proportional_to} G {sup 2}. In this application the photon mass is estimated. The SU (N) infrared regime is analysed by means of Alekseev-Arbuzov-Baikov's Lagrangian.
NASA Astrophysics Data System (ADS)
Crook, M. R.; Coles, B. R.; Ritter, C.; Cywinski, R.
1996-10-01
Neutron powder diffraction has been used to study the evolution of magnetic order with increasing Zr substitution in the C14 Laves phase compounds 0953-8984/8/41/022/img8. For compounds with x = 0.3 and x = 0.4 we find a simple antiferromagnetic structure, similar to that reported for isostructural 0953-8984/8/41/022/img9. In this structure the Fe moments at the 6h sites are aligned along the c-axis, ferromagnetically coupled within the a - b plane, with adjacent planes antiferromagnetically coupled. This spin structure results in a cancellation of the molecular field at the interplanar 2a sites, and the Fe atoms at these sites carry no ordered moment. The neutron diffraction measurements on 0953-8984/8/41/022/img10 compounds in the composition range 0953-8984/8/41/022/img11 provide evidence of a low-temperature spin-canted structure in which the antiferromagnetic structure described above is modified by the appearance of a basal-plane ferromagnetic component which in turn leads to a small ordered Fe moment at the 2a site. The temperature dependence of the staggered magnetization in the antiferromagnetic state of the x = 0.4 compounds is found to closely follow the form 0953-8984/8/41/022/img12, as predicted for weak itinerant antiferromagnets by SCR spin-fluctuation theory.
Competing Orders and Anomalies
Moon, Eun-Gook
2016-01-01
A conservation law is one of the most fundamental properties in nature, but a certain class of conservation “laws” could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the ’t Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed. PMID:27499184
Competing Orders and Anomalies
NASA Astrophysics Data System (ADS)
Moon, Eun-Gook
2016-08-01
A conservation law is one of the most fundamental properties in nature, but a certain class of conservation “laws” could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the ’t Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed.
Competing Orders and Anomalies.
Moon, Eun-Gook
2016-08-08
A conservation law is one of the most fundamental properties in nature, but a certain class of conservation "laws" could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the 't Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed.
Fauna Europaea - Orthopteroid orders.
Heller, Klaus-Gerhard; Bohn, Horst; Haas, Fabian; Willemse, Fer; de Jong, Yde
2016-01-01
Fauna Europaea provides a public web-service with an index of scientific names (including important synonyms) of all extant European terrestrial and freshwater animals, their geographical distribution at the level of countries and major islands (west of the Urals and excluding the Caucasus region), and some additional information. The Fauna Europaea project comprises about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies, which is much more than the originally projected number of 100,000 species. Fauna Europaea represents a huge effort by more than 400 contributing specialists throughout Europe and is a unique (standard) reference suitable for many users in science, government, industry, nature conservation and education. The "Orthopteroid orders" is one of the 58 Fauna Europaea major taxonomic groups. It contains series of mostly well-known insect orders: Embiodea (webspinners), Dermaptera (earwigs), Phasmatodea (walking sticks), Orthoptera s.s. (grasshoppers, crickets, bush-crickets) and Dictyoptera with the suborders Mantodea (mantids), Blattaria (cockroaches) and Isoptera (termites). For the Orthopteroid orders, data from 35 families containing 1,371 species are included in this paper.
Correlation, Cost Risk, and Geometry
NASA Technical Reports Server (NTRS)
Dean, Edwin B.
1992-01-01
The geometric viewpoint identifies the choice of a correlation matrix for the simulation of cost risk with the pairwise choice of data vectors corresponding to the parameters used to obtain cost risk. The correlation coefficient is the cosine of the angle between the data vectors after translation to an origin at the mean and normalization for magnitude. Thus correlation is equivalent to expressing the data in terms of a non orthogonal basis. To understand the many resulting phenomena requires the use of the tensor concept of raising the index to transform the measured and observed covariant components into contravariant components before vector addition can be applied. The geometric viewpoint also demonstrates that correlation and covariance are geometric properties, as opposed to purely statistical properties, of the variates. Thus, variates from different distributions may be correlated, as desired, after selection from independent distributions. By determining the principal components of the correlation matrix, variates with the desired mean, magnitude, and correlation can be generated through linear transforms which include the eigenvalues and the eigenvectors of the correlation matrix. The conversion of the data to a non orthogonal basis uses a compound linear transformation which distorts or stretches the data space. Hence, the correlated data does not have the same properties as the uncorrelated data used to generate it. This phenomena is responsible for seemingly strange observations such as the fact that the marginal distributions of the correlated data can be quite different from the distributions used to generate the data. The joint effect of statistical distributions and correlation remains a fertile area for further research. In terms of application to cost estimating, the geometric approach demonstrates that the estimator must have data and must understand that data in order to properly choose the correlation matrix appropriate for a given estimate
Correlated Electrons in Reduced Dimensions
Bonesteel, Nicholas E
2015-01-31
This report summarizes the work accomplished under the support of US DOE grant # DE-FG02-97ER45639, "Correlated Electrons in Reduced Dimensions." The underlying hypothesis of the research supported by this grant has been that studying the unique behavior of correlated electrons in reduced dimensions can lead to new ways of understanding how matter can order and how it can potentially be used. The systems under study have included i) fractional quantum Hall matter, which is realized when electrons are confined to two-dimensions and placed in a strong magnetic field at low temperature, ii) one-dimensional chains of spins and exotic quasiparticle excitations of topologically ordered matter, and iii) electrons confined in effectively ``zero-dimensional" semiconductor quantum dots.
NASA Astrophysics Data System (ADS)
Chattham, Nattaporn; Korblova, Eva; Shao, Renfan; Walba, David M.; Maclennan, Joseph E.; Clark, Noel A.
2010-02-01
Among the condensed phases, those of lowest point group symmetry are the triclinic crystals, which have only the identity element or the identity and inversion elements. Such low symmetry is stabilized by the specificity of molecular interaction, which is weakened with increasing disorder, so that known phases with fluid degrees of freedom are more symmetric. Here we report triclinic order, appearing as a broken symmetry in a single, isolated, fluid smectic liquid crystal layer freely suspended in air, showing that none of its principal dielectric axes lies either normal or parallel to the layer plane.
Chattham, Nattaporn; Korblova, Eva; Shao, Renfan; Walba, David M; Maclennan, Joseph E; Clark, Noel A
2010-02-12
Among the condensed phases, those of lowest point group symmetry are the triclinic crystals, which have only the identity element or the identity and inversion elements. Such low symmetry is stabilized by the specificity of molecular interaction, which is weakened with increasing disorder, so that known phases with fluid degrees of freedom are more symmetric. Here we report triclinic order, appearing as a broken symmetry in a single, isolated, fluid smectic liquid crystal layer freely suspended in air, showing that none of its principal dielectric axes lies either normal or parallel to the layer plane.
Information-limiting correlations
Moreno-Bote, Rubén; Beck, Jeffrey; Kanitscheider, Ingmar; Pitkow, Xaq; Latham, Peter; Pouget, Alexandre
2015-01-01
Computational strategies used by the brain strongly depend on the amount of information that can be stored in population activity, which in turn strongly depends on the pattern of noise correlations. In vivo, noise correlations tend to be positive and proportional to the similarity in tuning properties. Such correlations are thought to limit information, which has led to the suggestion that decorrelation increases information. In contrast, we found, analytically and numerically, that decorrelation does not imply an increase in information. Instead, the only information-limiting correlations are what we refer to as differential correlations: correlations proportional to the product of the derivatives of the tuning curves. Unfortunately, differential correlations are likely to be very small and buried under correlations that do not limit information, making them particularly difficult to detect. We found, however, that the effect of differential correlations on information can be detected with relatively simple decoders. PMID:25195105
NASA Astrophysics Data System (ADS)
Machado, J. Tenreiro
2015-01-01
Gottfried Leibniz generalized the derivation and integration, extending the operators from integer up to real, or even complex, orders. It is presently recognized that the resulting models capture long term memory effects difficult to describe by classical tools. Leon Chua generalized the set of lumped electrical elements that provide the building blocks in mathematical models. His proposal of the memristor and of higher order elements broadened the scope of variables and relationships embedded in the development of models. This paper follows the two directions and proposes a new logical step, by generalizing the concept of junction. Classical junctions interconnect system elements using simple algebraic restrictions. Nevertheless, this simplistic approach may be misleading in the presence of unexpected dynamical phenomena and requires including additional "parasitic" elements. The novel γ -junction includes, as special cases, the standard series and parallel connections and allows a new degree of freedom when building models. The proposal motivates the search for experimental and real world manifestations of the abstract conjectures.
Redundant correlation effect on personalized recommendation
NASA Astrophysics Data System (ADS)
Qiu, Tian; Han, Teng-Yue; Zhong, Li-Xin; Zhang, Zi-Ke; Chen, Guang
2014-02-01
The high-order redundant correlation effect is investigated for a hybrid algorithm of heat conduction and mass diffusion (HHM), through both heat conduction biased (HCB) and mass diffusion biased (MDB) correlation redundancy elimination processes. The HCB and MDB algorithms do not introduce any additional tunable parameters, but keep the simple character of the original HHM. Based on two empirical datasets, the Netflix and MovieLens, the HCB and MDB are found to show better recommendation accuracy for both the overall objects and the cold objects than the HHM algorithm. Our work suggests that properly eliminating the high-order redundant correlations can provide a simple and effective approach to accurate recommendation.
LCP correlations with improved resolution
NASA Astrophysics Data System (ADS)
Heilborn, Lauren; McIntosh, Alan; Jedele, Andrea; Youngs, Mike; Zarrella, Andrew; Yennello, Sherry
2016-09-01
Nuclear Equation of State (EoS) is important to a fundamental understanding of nuclear matter. The density dependence of the asymmetry energy, the least constrained term in the EoS, is critical to describing exotic systems such as neutron-rich heavy-ion collisions and neutron stars. Correlation functions of particles emitted in heavy ion reactions (such a p-p correlations) have been predicted to be sensitive to the asymmetry energy. In order to measure correlation functions with high resolution, the Forward Array Using Silicon Technology (FAUST) at the Cyclotron Institute at Texas A&M University has been recently re-commissioned with position-sensitive silicons as the delta-E detectors. A new method of position calibration for FAUST has been developed to take advantage of the 200um position resolution within each detector. Data has been collected from reactions of 40Ar +70Zn, 40Ar +58Fe and 40Ca +58Ni at 40 MeV/nucleon. The three systems allow correlation functions to be compared for systems with varying (N-Z)/A while holding constant either the total charge or the total mass. Light charged particles have been measured, and preliminary investigation of correlations from this campaign will be shown. Transport simulations will also be compared and presented.
Velocity correlations in laboratory insect swarms
NASA Astrophysics Data System (ADS)
Ni, R.; Ouellette, N. T.
2015-12-01
In contrast to animal groups such as bird flocks or migratory herds that display net, directed motion, insect swarms do not possess global order. Without such order, it is difficult to define and characterize the transition to collective behavior in swarms; nevertheless, visual observation of swarms strongly suggests that swarming insects do behave collectively. It has recently been suggested that correlation rather than order is the hallmark of emergent collective behavior. Here, we report measurements of spatial velocity correlation functions in laboratory mating swarms of the non-biting midge Chironomus riparius. Although we find some correlation at short distances, our swarms are in general only weakly correlated, in contrast to what has been observed in field studies. Our results hint at the potentially important role of environmental conditions on collective behavior, and suggest that general indicators of the collective nature of swarming are still needed.
Optomechanical Quantum Correlation Thermometry
NASA Astrophysics Data System (ADS)
Purdy, T. P.; Grutter, K. E.; Davanco, M. I.; Srinivasan, K.; Taylor, J. M.
We present an optomechanical approach for producing accurate thermometry over a wide temperature range using quantum Brownian motion. Optical measurements induce quantum correlations in an optomechanical system when quantum-limited intensity fluctuations of a probe laser drive mechanical motion. The size of the correlations in the weak probe limit are dictated by the scale of individual phonons. We have recently measured optomechanical quantum correlations in the cross correlation spectrum between the amplitude and phase fluctuations of a single probe laser interacting with a silicon nitride optomechanical crystal. These correlations are independent of thermally-induced Brownian motion. However, Brownian motion does simultaneously produce much larger correlation signals between other optical quadratures. A comparison of the size of thermally-induced correlations to quantum correlations allows us to absolutely calibrate Brownian motion thermometry to the mechanical energy quantization scale.
Comparing dependent robust correlations.
Wilcox, Rand R
2016-11-01
Let r1 and r2 be two dependent estimates of Pearson's correlation. There is a substantial literature on testing H0 : ρ1 = ρ2 , the hypothesis that the population correlation coefficients are equal. However, it is well known that Pearson's correlation is not robust. Even a single outlier can have a substantial impact on Pearson's correlation, resulting in a misleading understanding about the strength of the association among the bulk of the points. A way of mitigating this concern is to use a correlation coefficient that guards against outliers, many of which have been proposed. But apparently there are no results on how to compare dependent robust correlation coefficients when there is heteroscedasicity. Extant results suggest that a basic percentile bootstrap will perform reasonably well. This paper reports simulation results indicating the extent to which this is true when using Spearman's rho, a Winsorized correlation or a skipped correlation.
Ordered mesoporous metal oxides: synthesis and applications.
Ren, Yu; Ma, Zhen; Bruce, Peter G
2012-07-21
Great progress has been made in the preparation and application of ordered mesoporous metal oxides during the past decade. However, the applications of these novel and interesting materials have not been reviewed comprehensively in the literature. In the current review we first describe different methods for the preparation of ordered mesoporous metal oxides; we then review their applications in energy conversion and storage, catalysis, sensing, adsorption and separation. The correlations between the textural properties of ordered mesoporous metal oxides and their specific performance are highlighted in different examples, including the rate of Li intercalation, sensing, and the magnetic properties. These results demonstrate that the mesoporosity has a direct impact on the properties and potential applications of such materials. Although the scope of the current review is limited to ordered mesoporous metal oxides, we believe that the information may be useful for those working in a number of fields.
Parallel auto-correlative statistics with VTK.
Pebay, Philippe Pierre; Bennett, Janine Camille
2013-08-01
This report summarizes existing statistical engines in VTK and presents both the serial and parallel auto-correlative statistics engines. It is a sequel to [PT08, BPRT09b, PT09, BPT09, PT10] which studied the parallel descriptive, correlative, multi-correlative, principal component analysis, contingency, k-means, and order statistics engines. The ease of use of the new parallel auto-correlative statistics engine is illustrated by the means of C++ code snippets and algorithm verification is provided. This report justifies the design of the statistics engines with parallel scalability in mind, and provides scalability and speed-up analysis results for the autocorrelative statistics engine.
NASA Technical Reports Server (NTRS)
Surkis, Igor; Ken, Voitsekh; Melnikov, Alexey; Mishin, Vladimir; Sokolova, Nadezda; Shantyr, Violet; Zimovsky, Vladimir
2013-01-01
The activities of the six-station IAA RAS correlator include regular processing of national geodetic VLBI programs Ru-E, Ru-U, and Ru-F. The Ru-U sessions have been transferred in e-VLBI mode and correlated in the IAA Correlator Center automatically since 2011. The DiFX software correlator is used at the IAA in some astrophysical experiments.
Correlation after Asymmetrical Clipping,
1987-02-01
A general formula is derived for the correlation coefficient between clipped waveforms or among detection sequences, for the case where the clipping is asymmetric or the detection probability departs from 50%. The analytic arcsine law for symmetrical clipping is rehearsed and new analytic forms are found for asymmetrical clipping with high positive correlation, numerically low correlation and high negative correlation. Keywords: Sonar; Detection; Probability; Great Britain.
NASA Technical Reports Server (NTRS)
Sekido, Mamoru; Takefuji, Kazuhiro
2013-01-01
Kashima Space Technology Center (KSTC) is making use of two kinds of software correlators, the multi-channel K5/VSSP software correlator and the fast wide-band correlator 'GICO3,' for geodetic and R&D VLBI experiments. Overview of the activity and future plans are described in this paper.
Reverse Correlation in Neurophysiology
ERIC Educational Resources Information Center
Ringach, Dario; Shapley, Robert
2004-01-01
This article presents a review of reverse correlation in neurophysiology. We discuss the basis of reverse correlation in linear transducers and in spiking neurons. The application of reverse correlation to measure the receptive fields of visual neurons using white noise and m-sequences, and classical findings about spatial and color processing in…
Modified Biserial Correlation Coefficients.
ERIC Educational Resources Information Center
Kraemer, Helena Chmura
1981-01-01
Asymptotic distribution theory of Brogden's form of biserial correlation coefficient is derived and large sample estimates of its standard error obtained. Its relative efficiency to the biserial correlation coefficient is examined. Recommendations for choice of estimator of biserial correlation are presented. (Author/JKS)
Finding local order in cellular systems
NASA Astrophysics Data System (ADS)
Schneck, Emanuel; Wagermaier, Wolfgang
2017-01-01
Specific local arrangements of molecules are the structural fingerprints of important biological processes in cells and tissues but difficult to access experimentally. In the recent work by Bernhardt et al (2017 New J. Phys. 19 013012) such order on the nanometer scale has been investigated by in situ correlation of fluorescence-based cell visualization and nano-focused x-ray diffraction. This approach enables selective diffraction analysis guided by fluorescence imaging and opens new perspectives for the investigation of ordered nanostructures in living matter such as fiber bundles, membrane architectures, and newly-formed biominerals.
Quantum Fluctuations of a Superconductor Order Parameter
NASA Astrophysics Data System (ADS)
Arutyunov, K. Yu; Lehtinen, J. S.
2016-08-01
Tunneling I-V characteristics between very narrow titanium nanowires and "massive" superconducting aluminum were measured. The clear trend was observed: the thinner the titanium electrode, the broader the singularity at eV = Δ1(Al) + Δ2(Ti). The phenomenon can be explained by broadening of the gap edge of the quasi-one-dimensional titanium channels due to quantum fluctuations of the order parameter modulus |Δ2|. The range of the nanowire diameters, where the effect is pronounced, correlates with dimensions where the phase fluctuations of the complex superconducting order parameter Δ = |Δ|eiφ, the quantum phase slips, broadening the R(T) dependencies, have been observed.
Order-constrained linear optimization.
Tidwell, Joe W; Dougherty, Michael R; Chrabaszcz, Jeffrey S; Thomas, Rick P
2017-02-27
Despite the fact that data and theories in the social, behavioural, and health sciences are often represented on an ordinal scale, there has been relatively little emphasis on modelling ordinal properties. The most common analytic framework used in psychological science is the general linear model, whose variants include ANOVA, MANOVA, and ordinary linear regression. While these methods are designed to provide the best fit to the metric properties of the data, they are not designed to maximally model ordinal properties. In this paper, we develop an order-constrained linear least-squares (OCLO) optimization algorithm that maximizes the linear least-squares fit to the data conditional on maximizing the ordinal fit based on Kendall's τ. The algorithm builds on the maximum rank correlation estimator (Han, 1987, Journal of Econometrics, 35, 303) and the general monotone model (Dougherty & Thomas, 2012, Psychological Review, 119, 321). Analyses of simulated data indicate that when modelling data that adhere to the assumptions of ordinary least squares, OCLO shows minimal bias, little increase in variance, and almost no loss in out-of-sample predictive accuracy. In contrast, under conditions in which data include a small number of extreme scores (fat-tailed distributions), OCLO shows less bias and variance, and substantially better out-of-sample predictive accuracy, even when the outliers are removed. We show that the advantages of OCLO over ordinary least squares in predicting new observations hold across a variety of scenarios in which researchers must decide to retain or eliminate extreme scores when fitting data.
Oligorotaxane Radicals under Orders.
Wang, Yuping; Frasconi, Marco; Liu, Wei-Guang; Sun, Junling; Wu, Yilei; Nassar, Majed S; Botros, Youssry Y; Goddard, William A; Wasielewski, Michael R; Stoddart, J Fraser
2016-02-24
A strategy for creating foldameric oligorotaxanes composed of only positively charged components is reported. Threadlike components-namely oligoviologens-in which different numbers of 4,4'-bipyridinium (BIPY(2+)) subunits are linked by p-xylylene bridges, are shown to be capable of being threaded by cyclobis(paraquat-p-phenylene) (CBPQT(4+)) rings following the introduction of radical-pairing interactions under reducing conditions. UV/vis/NIR spectroscopic and electrochemical investigations suggest that the reduced oligopseudorotaxanes fold into highly ordered secondary structures as a result of the formation of BIPY(•+) radical cation pairs. Furthermore, by installing bulky stoppers at each end of the oligopseudorotaxanes by means of Cu-free alkyne-azide cycloadditions, their analogous oligorotaxanes, which retain the same stoichiometries as their progenitors, can be prepared. Solution-state studies of the oligorotaxanes indicate that their mechanically interlocked structures lead to the enforced interactions between the dumbbell and ring components, allowing them to fold (contract) in their reduced states and unfold (expand) in their fully oxidized states as a result of Coulombic repulsions. This electrochemically controlled reversible folding and unfolding process, during which the oligorotaxanes experience length contractions and expansions, is reminiscent of the mechanisms of actuation associated with muscle fibers.
Oligorotaxane Radicals under Orders
2016-01-01
A strategy for creating foldameric oligorotaxanes composed of only positively charged components is reported. Threadlike components—namely oligoviologens—in which different numbers of 4,4′-bipyridinium (BIPY2+) subunits are linked by p-xylylene bridges, are shown to be capable of being threaded by cyclobis(paraquat-p-phenylene) (CBPQT4+) rings following the introduction of radical-pairing interactions under reducing conditions. UV/vis/NIR spectroscopic and electrochemical investigations suggest that the reduced oligopseudorotaxanes fold into highly ordered secondary structures as a result of the formation of BIPY•+ radical cation pairs. Furthermore, by installing bulky stoppers at each end of the oligopseudorotaxanes by means of Cu-free alkyne–azide cycloadditions, their analogous oligorotaxanes, which retain the same stoichiometries as their progenitors, can be prepared. Solution-state studies of the oligorotaxanes indicate that their mechanically interlocked structures lead to the enforced interactions between the dumbbell and ring components, allowing them to fold (contract) in their reduced states and unfold (expand) in their fully oxidized states as a result of Coulombic repulsions. This electrochemically controlled reversible folding and unfolding process, during which the oligorotaxanes experience length contractions and expansions, is reminiscent of the mechanisms of actuation associated with muscle fibers. PMID:27163033
Maye, Alexander; Hsieh, Chih-hao; Sugihara, George; Brembs, Björn
2007-01-01
Brains are usually described as input/output systems: they transform sensory input into motor output. However, the motor output of brains (behavior) is notoriously variable, even under identical sensory conditions. The question of whether this behavioral variability merely reflects residual deviations due to extrinsic random noise in such otherwise deterministic systems or an intrinsic, adaptive indeterminacy trait is central for the basic understanding of brain function. Instead of random noise, we find a fractal order (resembling Lévy flights) in the temporal structure of spontaneous flight maneuvers in tethered Drosophila fruit flies. Lévy-like probabilistic behavior patterns are evolutionarily conserved, suggesting a general neural mechanism underlying spontaneous behavior. Drosophila can produce these patterns endogenously, without any external cues. The fly's behavior is controlled by brain circuits which operate as a nonlinear system with unstable dynamics far from equilibrium. These findings suggest that both general models of brain function and autonomous agents ought to include biologically relevant nonlinear, endogenous behavior-initiating mechanisms if they strive to realistically simulate biological brains or out-compete other agents. PMID:17505542
Digital Correlation By Optical Convolution/Correlation
NASA Astrophysics Data System (ADS)
Trimble, Joel; Casasent, David; Psaltis, Demetri; Caimi, Frank; Carlotto, Mark; Neft, Deborah
1980-12-01
Attention is given to various methods by which the accuracy achieveable and the dynamic range requirements of an optical computer can be enhanced. A new time position coding acousto-optic technique for optical residue arithmetic processing is presented and experimental demonstration is included. Major attention is given to the implementation of a correlator operating on digital or decimal encoded signals. Using a convolution description of multiplication, we realize such a correlator by optical convolution in one dimension and optical correlation in the other dimension of a optical system. A coherent matched spatial filter system operating on digital encoded signals, a noncoherent processor operating on complex-valued digital-encoded data, and a real-time multi-channel acousto-optic system for such operations are described and experimental verifications are included.
Orientational ordering and dynamics of rodlike polyelectrolytes.
Fazli, Hossein; Golestanian, Ramin; Kolahchi, Mohammad R
2005-07-01
The interplay between electrostatic interactions and orientational correlations is studied for a model system of charged rods positioned on a chain, using Monte Carlo simulation techniques. It is shown that the coupling brings about the notion of electrostatic frustration, which in turn results in: (i) a rich variety of orientational orderings such as chiral phases, and (ii) an inherently slow dynamics characterized by stretched-exponential behavior in the relaxation functions of the system.
Exploring intertwined orders in cuprate superconductors
NASA Astrophysics Data System (ADS)
Tranquada, John M.
2015-03-01
The concept of intertwined orders has been introduced to describe the cooperative relationship between antiferromagnetic spin correlations and electron (or hole) pair correlations that develop in copper-oxide superconductors. This contrasts with systems in which, for example, charge-density-wave (CDW) order competes for Fermi surface area with superconductivity. La2-xBaxCuO4 with x=0.125 provides an example in which the ordering of spin stripes coincides with the onset of two-dimensional superconducting correlations. The apparent frustration of the interlayer Josephson coupling has motivated the concept of the pair-density-wave superconductor, a state that theoretical calculations show to be energetically competitive with the uniform d-wave superconductor. Even at x=0.095, where there is robust superconductivity below 32 K in zero field, the coexistence of strong, low-energy, incommensurate spin excitations implies a spatially modulated and intertwined pair wave function. Recent observations of CDW order in YBa2Cu3O6+x and other cuprate families have raised interesting questions regarding the general role of charge modulations and the relation to superconductivity. While there are differences in the doping dependence of the modulation wave vectors in YBa2Cu3O6+x and La2-xBaxCuO4, the maximum ordering strength is peaked at the hole concentration of 1/8 in both cases. There are also possible connections with the quantum oscillations that have been detected about the same hole concentration but at high magnetic fields. Resolving these relationships remains a research challenge.
Exploring intertwined orders in cuprate superconductors
Tranquada, John M.
2014-11-22
In this study, the concept of intertwined orders has been introduced to describe the cooperative relationship between antiferromagnetic spin correlations and electron (or hole) pair correlations that develop in copper-oxide superconductors. This contrasts with systems in which, for example, charge-density-wave (CDW) order competes for Fermi surface area with superconductivity. La2-xBaxCuO4 with x = 0.125 provides an example in which the ordering of spin stripes coincides with the onset of two-dimensional superconducting correlations. The apparent frustration of the interlayer Josephson coupling has motivated the concept of the pair-density-wave superconductor, a state that theoretical calculations show to be energetically competitive with themore » uniform d-wave superconductor. Even at x = 0.095, where there is robust superconductivity below 32 K in zero field, the coexistence of strong, low-energy, incommensurate spin excitations implies a spatially modulated and intertwined pair wave function. Recent observations of CDW order in YBa2Cu3O6+x and other cuprate families have raised interesting questions regarding the general role of charge modulations and the relation to superconductivity. While there are differences in the doping dependence of the modulation wave vectors in YBa2Cu3O6+x and La2-xBaxCuO4, the maximum ordering strength is peaked at the hole concentration of 1/8 in both cases. There are also possible connections with the quantum oscillations that have been detected about the same hole concentration but at high magnetic fields. Resolving these relationships remains a research challenge.« less
Exploring intertwined orders in cuprate superconductors
Tranquada, John M.
2014-11-22
In this study, the concept of intertwined orders has been introduced to describe the cooperative relationship between antiferromagnetic spin correlations and electron (or hole) pair correlations that develop in copper-oxide superconductors. This contrasts with systems in which, for example, charge-density-wave (CDW) order competes for Fermi surface area with superconductivity. La_{2-x}Ba_{x}CuO_{4} with x = 0.125 provides an example in which the ordering of spin stripes coincides with the onset of two-dimensional superconducting correlations. The apparent frustration of the interlayer Josephson coupling has motivated the concept of the pair-density-wave superconductor, a state that theoretical calculations show to be energetically competitive with the uniform d-wave superconductor. Even at x = 0.095, where there is robust superconductivity below 32 K in zero field, the coexistence of strong, low-energy, incommensurate spin excitations implies a spatially modulated and intertwined pair wave function. Recent observations of CDW order in YBa_{2}Cu_{3}O_{6+x} and other cuprate families have raised interesting questions regarding the general role of charge modulations and the relation to superconductivity. While there are differences in the doping dependence of the modulation wave vectors in YBa_{2}Cu_{3}O_{6+x} and La_{2-x}Ba_{x}CuO_{4}, the maximum ordering strength is peaked at the hole concentration of 1/8 in both cases. There are also possible connections with the quantum oscillations that have been detected about the same hole concentration but at high magnetic fields. Resolving these relationships remains a research challenge.
48 CFR 53.216-1 - Delivery orders and orders under basic ordering agreements (OF 347).
Code of Federal Regulations, 2011 CFR
2011-10-01
... 48 Federal Acquisition Regulations System 2 2011-10-01 2011-10-01 false Delivery orders and orders under basic ordering agreements (OF 347). 53.216-1 Section 53.216-1 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION (CONTINUED) CLAUSES AND FORMS FORMS Prescription of Forms 53.216-1 Delivery orders and orders under...
Correlations in cosmic density fields
NASA Astrophysics Data System (ADS)
Bromley, B. C.
1994-12-01
A method is proposed to place constraints on the functional form of the high-order correlation functions zetan that arise in cosmic density fields at large scales. This technique is based on a mass-in-cell statistic and a difference of mass in partitions of a cell. The relationship between these measures is sensitive to the formal structure of the zetan as well as their amplitudes. This relationship is quantified in several theoretical models of structure, based on the hierarchical clustering paradigm. The results lead to a test for specific types of hierarchical clustering that is sensitive to correlations of all orders. The method is applied to examples of simulated large-scaled structure dominated by cold dark matter. In the preliminary study, the hierarchical paradigm appears to be a realistic approximation over a broad range of the scales. Furthermore, there is evidence that graphs of low-order vertices are dominant. On the basis of simulated data a phenomological model is specified that gives a good representation of clustering from linear scales to the strongly clustered regime (zeta2 approximately 500).
NASA Astrophysics Data System (ADS)
Tanda, Satoshi; Matsuyama, Toyoki; Oda, Migaku; Asano, Yasuhiro; Yakubo, Kousuke
2006-08-01
.]. Nanofibers of hydrogen storage alloy / I. Saita ... [et al.]. Synthesis of stable icosahedral quasicrystals in Zn-Sc based alloys and their magnetic properties / S. Kashimoto and T. Ishimasa. One-armed spiral wave excited by eam pressure in accretion disks in Be/X-Ray binaries / K. Hayasaki and A. T. Okazaki -- IV. Topological defects and excitations. Topological excitations in the ground state of charge density wave systems / P. Monceau. Soliton transport in nanoscale charge-density-wave systems / K. Inagaki, T. Toshima and S. Tanda. Topological defects in triplet superconductors UPt3, Sr[symbol]RuO[symbol], etc. / K. Maki ... [et al.]. Microscopic structure of vortices in type II superconductors / K. Machida ... [et al.]. Microscopic neutron investigation of the Abrikosov state of high-temperature superconductors / J. Mesot. Energy dissipation at nano-scale topological defects of high-Tc superconductors: microwave study / A. Maeda. Pressure induced topological phase transition in the heavy Fermion compound CeAl[symbol] / H. Miyagawa ... [et al.]. Explanation for the unusual orientation of LSCO square vortex lattice in terms of nodal superconductivity / M. Oda. Local electronic states in Bi[symbol]Sr[symbol]CaCu[symbol]O[symbol] / A. Hashimoto ... [et al.] -- V. Topology in quantum phenomena. Topological vortex formation in a Bose-Einstein condensate of alkali-metal atoms / M. Nakahara. Quantum phase transition of [symbol]He confined in nano-porous media / K. Shirahama, K. Yamamoto and Y. Shibayama. A new mean-field theory for Bose-Einstein condensates / T. Kita. Spin current in topological cristals / Y. Asano. Antiferromagnetic defects in non-magnetic hidden order of the heavy-electron system URu[symbol]Si[symbol] / H. Amitsuka, K. Tenya and M. Yokoyama. Magnetic-field dependences of thermodynamic quantities in the vortex state of Type-II superconductors / K. Watanabe, T. Kita and M. Arai. Three-magnon-mediated nuclear spin relaxation in quantum ferrimagnets of topological
Photoinduced ultrafast charge-order melting: Charge-order inversion and nonthermal effects
van Veenendaal, Michel
2016-09-01
The effect of photoexcitation is studied for a system with checkerboard charge order induced by displacements of ligands around a metal site. The motion of the ligands is treated classically and the electronic charges are simplified to two-level molecular bond charges. The calculations are done for a checkerboard charge-ordered system with about 100 000 ligand oscillators coupled to a fixed-temperature bath. The initial photoexcitation is followed by a rapid decrease in the charge-order parameter within 50–100 femtoseconds while leaving the correlation length almost unchanged. Depending on the fluence, a complete melting of the charge order occurs in less than amore » picosecond. While for low fluences, the system returns to its original state, for full melting, it recovers to its broken-symmetry state leading to an inversion of the charge order. Finally, for small long-range interactions, recovery can be slow due to domain formation.« less
Photoinduced ultrafast charge-order melting: Charge-order inversion and nonthermal effects
van Veenendaal, Michel
2016-09-01
The effect of photoexcitation is studied for a system with checkerboard charge order induced by displacements of ligands around a metal site. The motion of the ligands is treated classically and the electronic charges are simplified to two-level molecular bond charges. The calculations are done for a checkerboard charge-ordered system with about 100 000 ligand oscillators coupled to a fixed-temperature bath. The initial photoexcitation is followed by a rapid decrease in the charge-order parameter within 50–100 femtoseconds while leaving the correlation length almost unchanged. Depending on the fluence, a complete melting of the charge order occurs in less than a picosecond. While for low fluences, the system returns to its original state, for full melting, it recovers to its broken-symmetry state leading to an inversion of the charge order. For small long-range interactions, recovery can be slow due to domain formation.
Photoinduced ultrafast charge-order melting: Charge-order inversion and nonthermal effects
van Veenendaal, Michel
2016-09-01
The effect of photoexcitation is studied for a system with checkerboard charge order induced by displacements of ligands around a metal site. The motion of the ligands is treated classically and the electronic charges are simplified to two-level molecular bond charges. The calculations are done for a checkerboard charge-ordered system with about 100 000 ligand oscillators coupled to a fixed-temperature bath. The initial photoexcitation is followed by a rapid decrease in the charge-order parameter within 50–100 femtoseconds while leaving the correlation length almost unchanged. Depending on the fluence, a complete melting of the charge order occurs in less than a picosecond. While for low fluences, the system returns to its original state, for full melting, it recovers to its broken-symmetry state leading to an inversion of the charge order. Finally, for small long-range interactions, recovery can be slow due to domain formation.
Structural order and disorder in Precambrian kerogens
Buseck, P.R.; Bo-Jun, H.; Miner, B.
1988-01-01
High-resolution transmission electron microscopy (HRTEM) has been used to examine the structures of a wide range of Precambrian kerogens from rocks with ages between 0.9 and 3.8 billion years. The authors find recognizable structural ordering in samples that show little or no evidence of crystallinity by powder X-ray diffraction measurements. A wide range in degree of ordering is evident in the HRTEM images. A rough correlation exists between the ordering displayed in the HRTEM images and both the sample ages and their H/C ratios. Many kerogen samples are structurally heterogeneous, possibly reflecting a variety of precursors, and source regions. The observed structural heterogeneities probably extend to other parameters; when isotopic and X-ray measurements can be made on the same scale as HRTEM images, similar scatter presumably will also be evident.
Next-order structure-function equations
NASA Astrophysics Data System (ADS)
Hill, Reginald J.; Boratav, Olus N.
2001-01-01
Kolmogorov's equation [Dokl. Akad. Nauk SSSR 32, 16 (1941)] relates the two-point second- and third-order velocity structure functions and the energy dissipation rate. The analogous next higher-order two-point equation relates the third- and fourth-order velocity structure functions and the structure function of the product of pressure-gradient difference and two factors of velocity difference, denoted Tijk. The equation is simplified on the basis of local isotropy. Laboratory and numerical simulation data are used to evaluate and compare terms in the equation, examine the balance of the equation, and evaluate components of Tijk. Atmospheric surface-layer data are used to evaluate Tijk in the inertial range. Combined with the random sweeping hypothesis, the equation relates components of the fourth-order velocity structure function. Data show the resultant error of this application of random sweeping. The next-order equation constrains the relationships that have been suggested among components of the fourth-order velocity structure function. The pressure structure function, pressure-gradient correlation, and mean-squared pressure gradient are related to Tijk. Inertial range formulas are discussed.
Asymmetric magnon excitation by spontaneous toroidal ordering
Hayami, Satoru; Kusunose, Hiroaki; Motome, Yukitoshi
2016-04-12
The effects of spontaneous toroidal ordering on magnetic excitation are theoretically investigated for a localized spin model that includes a staggered Dzyaloshinsky–Moriya interaction and anisotropic exchange interactions, which arise from the antisymmetric spin–orbit coupling and the multiorbital correlation effect. We show that the model exhibits a Néel-type antiferromagnetic order, which simultaneously accompanies a ferroic toroidal order. We find that the occurrence of toroidal order modulates the magnon dispersion in an asymmetric way with respect to the wave number: a toroidal dipole order on the zigzag chain leads to a band-bottom shift, while a toroidal octupole order on the honeycomb latticemore » gives rise to a valley splitting. These asymmetric magnon excitations could be a source of unusual magnetic responses, such as nonreciprocal magnon transport. A variety of modulations are discussed while changing the lattice and magnetic symmetries. Furthermore, the implications regarding candidate materials for asymmetric magnon excitations are presented.« less
Preselected Sub-Poissonian Correlations
NASA Technical Reports Server (NTRS)
Pavicic, Mladen
1996-01-01
The simplest possible photon-number-squeezed states containing only two photons and exhibiting sub-poissonian statistics with the Fano factor approaching 0.5 have been used for a proposal of a loophole-free Bell experiment requiring only 67 percent of detection efficiency. The states are obtained by the fourth order interference first of two downconverted photons at an asymmetrical beam splitter and thereupon of two photons from two independent singlets at an asymmetrical beam splitter. In the latter set-up, the other two photons which nowhere interacted and whose paths never crossed appear entangled in a singlet-like correlated state.
Magnetic correlations in a classic Mott system
Bao, W.; Broholm, C.; Aeppli, G.; Carter, S.A.; Dai, D.; Frost, C.D.; Honig, J.M.; Metcalf, P.
1997-07-01
The metal-insulator transition in V{sub 2}O{sub 3} causes a fundamental change in its magnetism. While the antiferromagnetic insulator (AFI) is a Heisenberg localized spin system, the antiferromagnetism in the strongly correlated metal is determined by a Fermi surface instability. Paramagnetic fluctuations in the metal and insulator represent similar spatial spin correlations, but are unrelated to the long range order in the AFI. The phase transition to the AFI induces an abrupt switching of magnetic correlations to a different magnetic wave vector. The AFI transition, therefore, is not a conventional spin order-disorder transition. Instead it is accounted for by an ordering in the occupation of the two degenerate d-orbitals at the Fermi level.
Pfaffian Correlation Functions of Planar Dimer Covers
NASA Astrophysics Data System (ADS)
Aizenman, Michael; Valcázar, Manuel Laínz; Warzel, Simone
2017-01-01
The Pfaffian structure of the boundary monomer correlation functions in the dimer-covering planar graph models is rederived through a combinatorial/topological argument. These functions are then extended into a larger family of order-disorder correlation functions which are shown to exhibit Pfaffian structure throughout the bulk. Key tools involve combinatorial switching symmetries which are identified through the loop-gas representation of the double dimer model, and topological implications of planarity.
ALMA correlator computer systems
NASA Astrophysics Data System (ADS)
Pisano, Jim; Amestica, Rodrigo; Perez, Jesus
2004-09-01
We present a design for the computer systems which control, configure, and monitor the Atacama Large Millimeter Array (ALMA) correlator and process its output. Two distinct computer systems implement this functionality: a rack- mounted PC controls and monitors the correlator, and a cluster of 17 PCs process the correlator output into raw spectral results. The correlator computer systems interface to other ALMA computers via gigabit Ethernet networks utilizing CORBA and raw socket connections. ALMA Common Software provides the software infrastructure for this distributed computer environment. The control computer interfaces to the correlator via multiple CAN busses and the data processing computer cluster interfaces to the correlator via sixteen dedicated high speed data ports. An independent array-wide hardware timing bus connects to the computer systems and the correlator hardware ensuring synchronous behavior and imposing hard deadlines on the control and data processor computers. An aggregate correlator output of 1 gigabyte per second with 16 millisecond periods and computational data rates of approximately 1 billion floating point operations per second define other hard deadlines for the data processing computer cluster.
Image Correlation Method for DNA Sequence Alignment
Curilem Saldías, Millaray; Villarroel Sassarini, Felipe; Muñoz Poblete, Carlos; Vargas Vásquez, Asticio; Maureira Butler, Iván
2012-01-01
The complexity of searches and the volume of genomic data make sequence alignment one of bioinformatics most active research areas. New alignment approaches have incorporated digital signal processing techniques. Among these, correlation methods are highly sensitive. This paper proposes a novel sequence alignment method based on 2-dimensional images, where each nucleic acid base is represented as a fixed gray intensity pixel. Query and known database sequences are coded to their pixel representation and sequence alignment is handled as object recognition in a scene problem. Query and database become object and scene, respectively. An image correlation process is carried out in order to search for the best match between them. Given that this procedure can be implemented in an optical correlator, the correlation could eventually be accomplished at light speed. This paper shows an initial research stage where results were “digitally” obtained by simulating an optical correlation of DNA sequences represented as images. A total of 303 queries (variable lengths from 50 to 4500 base pairs) and 100 scenes represented by 100 x 100 images each (in total, one million base pair database) were considered for the image correlation analysis. The results showed that correlations reached very high sensitivity (99.01%), specificity (98.99%) and outperformed BLAST when mutation numbers increased. However, digital correlation processes were hundred times slower than BLAST. We are currently starting an initiative to evaluate the correlation speed process of a real experimental optical correlator. By doing this, we expect to fully exploit optical correlation light properties. As the optical correlator works jointly with the computer, digital algorithms should also be optimized. The results presented in this paper are encouraging and support the study of image correlation methods on sequence alignment. PMID:22761742
Image correlation method for DNA sequence alignment.
Curilem Saldías, Millaray; Villarroel Sassarini, Felipe; Muñoz Poblete, Carlos; Vargas Vásquez, Asticio; Maureira Butler, Iván
2012-01-01
The complexity of searches and the volume of genomic data make sequence alignment one of bioinformatics most active research areas. New alignment approaches have incorporated digital signal processing techniques. Among these, correlation methods are highly sensitive. This paper proposes a novel sequence alignment method based on 2-dimensional images, where each nucleic acid base is represented as a fixed gray intensity pixel. Query and known database sequences are coded to their pixel representation and sequence alignment is handled as object recognition in a scene problem. Query and database become object and scene, respectively. An image correlation process is carried out in order to search for the best match between them. Given that this procedure can be implemented in an optical correlator, the correlation could eventually be accomplished at light speed. This paper shows an initial research stage where results were "digitally" obtained by simulating an optical correlation of DNA sequences represented as images. A total of 303 queries (variable lengths from 50 to 4500 base pairs) and 100 scenes represented by 100 x 100 images each (in total, one million base pair database) were considered for the image correlation analysis. The results showed that correlations reached very high sensitivity (99.01%), specificity (98.99%) and outperformed BLAST when mutation numbers increased. However, digital correlation processes were hundred times slower than BLAST. We are currently starting an initiative to evaluate the correlation speed process of a real experimental optical correlator. By doing this, we expect to fully exploit optical correlation light properties. As the optical correlator works jointly with the computer, digital algorithms should also be optimized. The results presented in this paper are encouraging and support the study of image correlation methods on sequence alignment.
Protective orders: questions and conundrums.
Logan, T K; Shannon, Lisa; Walker, Robert; Faragher, Teri Marie
2006-07-01
Current media portrayal of protective orders is often negative, focusing on weaknesses in how protective orders are obtained and enforced. This review of research findings on protective orders examines issues and suggests areas in need of future research to clarify and improve public policy. More specifically, this review has five main objectives: (a) to provide background information about partner violence and the need for protective orders; (b) to describe what protective orders are, how many women obtain them, and the advantages and disadvantages of obtaining protective orders; (c) to examine characteristics of women who seek protective orders; (d) to explore research on whether protective orders actually increase women's safety; and (e) to highlight opportunities and gaps in the practice and research literature regarding the use of protective orders for women with violent partners or ex-partners.
Quantifying Nanoscale Order in Amorphous Materials via Fluctuation Electron Microscopy
ERIC Educational Resources Information Center
Bogle, Stephanie Nicole
2009-01-01
Fluctuation electron microscopy (FEM) has been used to study the nanoscale order in various amorphous materials. The method is explicitly sensitive to 3- and 4-body atomic correlation functions in amorphous materials; this is sufficient to establish the existence of structural order on the nanoscale, even when the radial distribution function…
Estimation of the simple correlation coefficient.
Shieh, Gwowen
2010-11-01
This article investigates some unfamiliar properties of the Pearson product-moment correlation coefficient for the estimation of simple correlation coefficient. Although Pearson's r is biased, except for limited situations, and the minimum variance unbiased estimator has been proposed in the literature, researchers routinely employ the sample correlation coefficient in their practical applications, because of its simplicity and popularity. In order to support such practice, this study examines the mean squared errors of r and several prominent formulas. The results reveal specific situations in which the sample correlation coefficient performs better than the unbiased and nearly unbiased estimators, facilitating recommendation of r as an effect size index for the strength of linear association between two variables. In addition, related issues of estimating the squared simple correlation coefficient are also considered.
Dynamical correlations after a quantum quench.
Essler, Fabian H L; Evangelisti, Stefano; Fagotti, Maurizio
2012-12-14
We consider dynamic (non-equal-time) correlation functions of local observables after a quantum quench. We show that, in the absence of long-range interactions in the final Hamiltonian, the dynamics is determined by the same ensemble that describes static (equal-time) correlations. For many integrable models, static correlation functions of local observables after a quantum quench relax to stationary values, which are described by a generalized Gibbs ensemble. The same generalized Gibbs ensemble then determines dynamic correlation functions, and the basic form of the fluctuation dissipation theorem holds, although the absorption and emission spectra are not simply related as in the thermal case. For quenches in the transverse field Ising chain, we derive explicit expressions for the time evolution of dynamic order parameter correlators after a quench.
Local Magnetic Order vs Superconductivity in a Layered Cuprate
NASA Astrophysics Data System (ADS)
Ichikawa, N.; Uchida, S.; Tranquada, J. M.; Niemöller, T.; Gehring, P. M.; Lee, S.-H.; Schneider, J. R.
2000-08-01
We report on the phase diagram for charge-stripe order in La1.6-xNd0.4SrxCuO4, determined by neutron and x-ray scattering studies and resistivity measurements. From an analysis of the in-plane resistivity motivated by recent nuclear-quadrupole-resonance studies, we conclude that the transition temperature for local charge ordering decreases monotonically with x, and hence that local antiferromagnetic order is uniquely correlated with the anomalous depression of superconductivity at x~18. This result is consistent with theories in which superconductivity depends on the existence of charge-stripe correlations.
Local magnetic order vs superconductivity in a layered cuprate
Ichikawa; Uchida; Tranquada; Niemoller; Gehring; Lee; Schneider
2000-08-21
We report on the phase diagram for charge-stripe order in La1.6-xNd0. 4SrxCuO4, determined by neutron and x-ray scattering studies and resistivity measurements. From an analysis of the in-plane resistivity motivated by recent nuclear-quadrupole-resonance studies, we conclude that the transition temperature for local charge ordering decreases monotonically with x, and hence that local antiferromagnetic order is uniquely correlated with the anomalous depression of superconductivity at x approximately 1 / 8. This result is consistent with theories in which superconductivity depends on the existence of charge-stripe correlations.
Chien, M.C.H.; Monroy, M.R.
1986-01-01
The Liquid density predicted by the Peng-Robinson (P-R) equation of state is often off by 10% or more at temperature and pressure conditions encountered in most reservoirs. To improve the density predictions, two new density correlations have been developed. The first correlation is based on the chain-of-rotators (COR) equation of state and the second is based on the three-parameter Peng-Robinson (PR3) equation of state. The COR correlation is applicable to wider pressure and temperature ranges, but is computationally expensive. It is suited for interpreting fluid-analysis data, where no extensive phase-behavior calculations are needed. On the other hand, the PR3 correlation is more limited in its application range, but is computationally more efficient. It is particularly suited for compositional reservoir simulation where many density calculations are repeatedly carried out. In general, both correlations are comparable to the Standing-Katz correlation for liquid-density calculation and comparable to the P-R equation of state for vapor-density calculation. However, they are superior to the Standing-Katz correlation for liquid mixtures near critical points or liquid mixtures at high pressures. Overall, the COR equation of state gives an average prediction error of 1.9% for liquid densities and 2.7% for vapor densities, and the PR3 gives an average prediction error of less than 2% for both liquid and vapor densities.
Higher-Order Mentalising and Executive Functioning
2015-01-01
Higher-order mentalising is the ability to represent the beliefs and desires of other people at multiple, iterated levels – a capacity that sets humans apart from other species. However, there has not yet been a systematic attempt to determine what cognitive processes underlie this ability. Here we present three correlational studies assessing the extent to which performance on higher-order mentalising tasks relates to emotion recognition, self-reported empathy and self-inhibition. In Study 1a and 1b, examining emotion recognition and empathy, a relationship was identified between individual differences in the ability to mentalise and an emotion recognition task (the Reading the Mind in the Eyes task), but no correlation was found with the Empathy Quotient, a self-report scale of empathy. Study 2 investigated whether a relationship exists between individual mentalising abilities and four different forms of self-inhibition: motor inhibition, executive inhibition, automatic imitation and temporal discounting. Results demonstrate that only temporal discounting performance relates to mentalising ability; suggesting that cognitive skills relevant to representation of the minds of others’ are not influenced by the ability to perform more basic inhibition. Higher-order mentalising appears to rely on the cognitive architecture that serves both low-level social cognition (emotion recognition), and complex forms of inhibition. PMID:26543298
Higher-Order Mentalising and Executive Functioning.
2015-11-01
Higher-order mentalising is the ability to represent the beliefs and desires of other people at multiple, iterated levels - a capacity that sets humans apart from other species. However, there has not yet been a systematic attempt to determine what cognitive processes underlie this ability. Here we present three correlational studies assessing the extent to which performance on higher-order mentalising tasks relates to emotion recognition, self-reported empathy and self-inhibition. In Study 1a and 1b, examining emotion recognition and empathy, a relationship was identified between individual differences in the ability to mentalise and an emotion recognition task (the Reading the Mind in the Eyes task), but no correlation was found with the Empathy Quotient, a self-report scale of empathy. Study 2 investigated whether a relationship exists between individual mentalising abilities and four different forms of self-inhibition: motor inhibition, executive inhibition, automatic imitation and temporal discounting. Results demonstrate that only temporal discounting performance relates to mentalising ability; suggesting that cognitive skills relevant to representation of the minds of others' are not influenced by the ability to perform more basic inhibition. Higher-order mentalising appears to rely on the cognitive architecture that serves both low-level social cognition (emotion recognition), and complex forms of inhibition.
Correlated Temporal and Spectral Variability
NASA Technical Reports Server (NTRS)
Swank, Jean H.
2007-01-01
The variability of neutron star and black hole X-ray sources has several dimensions, because of the roles played by different important time-scales. The variations on time scales of hours, weeks, and months, ranging from 50% to orders of magnitude, arise out of changes in the flow in the disk. The most important driving forces for those changes are probably various possible instabilities in the disk, though there may be effects with other dominant causes. The changes in the rate of flow appear to be associated with changes in the flow's configuration, as the accreting material approaches the compact object, for there are generally correlated changes in both the Xray spectra and the character of the faster temporal variability. There has been a lot of progress in tracking these correlations, both for Z and Atoll neutron star low-mass X-ray binaries, and for black hole binaries. I will discuss these correlations and review briefly what they tell us about the physical states of the systems.
Haystack Observatory VLBI Correlator
NASA Technical Reports Server (NTRS)
Titus, Mike; Cappallo, Roger; Corey, Brian; Dudevoir, Kevin; Niell, Arthur; Whitney, Alan
2013-01-01
This report summarizes the activities of the Haystack Correlator during 2012. Highlights include finding a solution to the DiFX InfiniBand timeout problem and other DiFX software development, conducting a DBE comparison test following the First International VLBI Technology Workshop, conducting a Mark IV and DiFX correlator comparison, more broadband delay experiments, more u- VLBI Galactic Center observations, and conversion of RDV session processing to the Mark IV/HOPS path. Non-real-time e-VLBI transfers and engineering support of other correlators continued.
Olson Order of Quantum Observables
NASA Astrophysics Data System (ADS)
Dvurečenskij, Anatolij
2016-11-01
M.P. Olson, Proc. Am. Math. Soc. 28, 537-544 (1971) showed that the system of effect operators of the Hilbert space can be ordered by the so-called spectral order such that the system of effect operators is a complete lattice. Using his ideas, we introduce a partial order, called the Olson order, on the set of bounded observables of a complete lattice effect algebra. We show that the set of bounded observables is a Dedekind complete lattice.
... order; DNR; DNR order; Advance care directive - DNR; Health care agent - DNR; Health care proxy - DNR; End-of-life - DNR; Living will - ... medical order written by a doctor. It instructs health care providers not to do cardiopulmonary resuscitation (CPR) if ...
A correlated electromechanical system
NASA Astrophysics Data System (ADS)
Mahboob, I.; Villiers, M.; Nishiguchi, K.; Hatanaka, D.; Fujiwara, A.; Yamaguchi, H.
2017-03-01
A correlation with phonons sustained by a pair of electromechanical resonators that differ both in size and frequency is demonstrated. In spite of the electromechanical resonators being spatially distinct, they can still be strongly dynamically coupled via a classical analogue of the beam splitter interaction with a cooperativity exceeding five, and parametric down-conversion which results in both resonators self-oscillating. This latter regime yields a classical variant of a two-mode squeezed state which is identified as perfectly correlated phase-locked vibrations between the two resonators. The creation of a correlation between two separate mechanical resonators suggests that extending this interaction to vacuum phonon states could enable a macroscopic two-mode squeezed state to be generated. Conversely, the ability to resolve the correlated state via the self-oscillations could be harnessed to build a new class of detector where an external stimulus neutralises the phase-locked vibrations.
Ozone Correlative Measurements Workshop
NASA Technical Reports Server (NTRS)
Hilsenrath, E. (Editor)
1985-01-01
A study was conducted to determine the necessary parameters for the correlation of data on Earth ozone. Topics considered were: (1) measurement accuracy; (2) equipment considerations (SBUV); and (3) ground based measurements to support satellite data.
Examining Correlates of Diversity.
ERIC Educational Resources Information Center
Raudenbush, Stephen W.; Bryk, Anthony S.
1987-01-01
Statistical methods are presented for studying "correlates of diversity," defined as characteristics of educational organizations that predict dispersion on the dependent variable. Strategies based on exact distribution theory and asymptotic normal approximation are considered. (TJH)
NASA Technical Reports Server (NTRS)
Kurihara, Shinobu; Nozawa, Kentaro
2013-01-01
The K5/VSSP software correlator (Figure 1), located in Tsukuba, Japan, is operated by the Geospatial Information Authority of Japan (GSI). It is fully dedicated to processing the geodetic VLBI sessions of the International VLBI Service for Geodesy and Astrometry. All of the weekend IVS Intensives (INT2) and the Japanese domestic VLBI observations organized by GSI were processed at the Tsukuba VLBI Correlator.
Spatial variability of correlated color temperature of lightning channels
NASA Astrophysics Data System (ADS)
Shimoji, Nobuaki; Aoyama, Ryoma; Hasegawa, Wataru
In this paper, we present the spatial variability of the correlated color temperature of lightning channel shown in a digital still image. In order to analyze the correlated color temperature, we calculated chromaticity coordinates of the lightning channels in the digital still image. From results, the spatial variation of the correlated color temperature of the lightning channel was confirmed. Moreover, the results suggest that the correlated color temperature and peak current of the lightning channels are related to each other.
Ordered delinquency: the "effects" of birth order on delinquency.
Cundiff, Patrick R
2013-08-01
Juvenile delinquency has long been associated with birth order in popular culture. While images of the middle child acting out for attention or the rebellious youngest child readily spring to mind, little research has attempted to explain why. Drawing from Adlerian birth order theory and Sulloway's born-to-rebel hypothesis, I examine the relationship between birth order and a variety of delinquent outcomes during adolescence. Following some recent research on birth order and intelligence, I use new methods that allow for the examination of between-individual and within-family differences to better address the potential spurious relationship. My findings suggest that contrary to popular belief, the relationship between birth order and delinquency is spurious. Specifically, I find that birth order effects on delinquency are spurious and largely products of the analytic methods used in previous tests of the relationship. The implications of this finding are discussed.
A reduction of order two for infinite-order Lagrangians
NASA Astrophysics Data System (ADS)
Jaén, X.; Llosa, J.; Molina, A.
1986-10-01
Given a Lagrangian system depending on the position derivatives of any order, and assuming that certain conditions are satisfied, a second-order differential system is obtained such that its solutions also satisfy the Euler equations derived from the original Lagrangian. A generalization of the singular Lagrangian formalism permits a reduction of order keeping the canonical formalism in sight. Finally, the general results obtained in the first part of the paper are applied to Wheeler-Feynman electrodynamics for two charged point particles up to order 1/c4.
Code of Federal Regulations, 2013 CFR
2013-01-01
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Code of Federal Regulations, 2011 CFR
2011-01-01
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Code of Federal Regulations, 2010 CFR
2010-01-01
... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PEANUT PROMOTION, RESEARCH, AND INFORMATION ORDER Peanut Promotion, Research, and Information Order Definitions § 1216.16 Order. Order...
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2012-01-01
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Code of Federal Regulations, 2011 CFR
2011-01-01
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Code of Federal Regulations, 2014 CFR
2014-01-01
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Code of Federal Regulations, 2013 CFR
2013-01-01
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Code of Federal Regulations, 2010 CFR
2010-01-01
... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE LAMB PROMOTION, RESEARCH, AND INFORMATION ORDER Lamb Promotion, Research, and Information Order Definitions § 1280.113 Order. Order means...
Quantum Fluctuations of a Superconductor Order Parameter.
Arutyunov, K Yu; Lehtinen, J S
2016-12-01
Tunneling I-V characteristics between very narrow titanium nanowires and "massive" superconducting aluminum were measured. The clear trend was observed: the thinner the titanium electrode, the broader the singularity at eV = Δ1(Al) + Δ2(Ti). The phenomenon can be explained by broadening of the gap edge of the quasi-one-dimensional titanium channels due to quantum fluctuations of the order parameter modulus |Δ2|. The range of the nanowire diameters, where the effect is pronounced, correlates with dimensions where the phase fluctuations of the complex superconducting order parameter Δ = |Δ|e(iφ), the quantum phase slips, broadening the R(T) dependencies, have been observed.
Vorticity, defects and correlations in active turbulence
Thampi, Sumesh P.; Golestanian, Ramin; Yeomans, Julia M.
2014-01-01
We describe a numerical investigation of a continuum model of an active nematic, concentrating on the regime of active turbulence. Results are presented for the effect of three parameters, activity, elastic constant and rotational diffusion constant, on the order parameter and flow fields. Defects and distortions in the director field act as sources of vorticity, and thus vorticity is strongly correlated to the director field. In particular, the characteristic length of decay of vorticity and order parameter correlations is controlled by the defect density. By contrast, the decay of velocity correlations is determined by a balance between activity and dissipation. We highlight the role of microscopic flow generation mechanisms in determining the flow patterns and characteristic scales of active turbulence and contrast the behaviour of extensile and contractile active nematics. PMID:25332382
Vorticity, defects and correlations in active turbulence.
Thampi, Sumesh P; Golestanian, Ramin; Yeomans, Julia M
2014-11-28
We describe a numerical investigation of a continuum model of an active nematic, concentrating on the regime of active turbulence. Results are presented for the effect of three parameters, activity, elastic constant and rotational diffusion constant, on the order parameter and flow fields. Defects and distortions in the director field act as sources of vorticity, and thus vorticity is strongly correlated to the director field. In particular, the characteristic length of decay of vorticity and order parameter correlations is controlled by the defect density. By contrast, the decay of velocity correlations is determined by a balance between activity and dissipation. We highlight the role of microscopic flow generation mechanisms in determining the flow patterns and characteristic scales of active turbulence and contrast the behaviour of extensile and contractile active nematics.
40 CFR 305.27 - Accelerated order, order to dismiss.
Code of Federal Regulations, 2012 CFR
2012-07-01
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Code of Federal Regulations, 2011 CFR
2011-07-01
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Code of Federal Regulations, 2013 CFR
2013-07-01
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Code of Federal Regulations, 2010 CFR
2010-07-01
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40 CFR 305.27 - Accelerated order, order to dismiss.
Code of Federal Regulations, 2014 CFR
2014-07-01
..., AND LIABILITY ACT (CERCLA) ADMINISTRATIVE HEARING PROCEDURES FOR CLAIMS AGAINST THE SUPERFUND... 40 Protection of Environment 28 2014-07-01 2014-07-01 false Accelerated order, order to dismiss. 305.27 Section 305.27 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)...
Ordering within Moral Orders to Manage Classroom Trouble
ERIC Educational Resources Information Center
Doherty, Catherine; McGregor, Rowena; Shield, Paul
2016-01-01
This paper demonstrates how classroom trouble warranting teacher intervention can stem from transgressions in different layers of the complex moral order regulating classroom interactions. The paper builds from Durkheim's treatment of schooling as the institution responsible for the inculcation of a shared moral order, Bernstein's distinction…
Counterbalancing for Serial Order Carryover Effects in Experimental Condition Orders
ERIC Educational Resources Information Center
Brooks, Joseph L.
2012-01-01
Reactions of neural, psychological, and social systems are rarely, if ever, independent of previous inputs and states. The potential for serial order carryover effects from one condition to the next in a sequence of experimental trials makes counterbalancing of condition order an essential part of experimental design. Here, a method is proposed…
NASA Astrophysics Data System (ADS)
Ruigrok, Elmer; Gibbons, Steven; Wapenaar, Kees
2016-10-01
An areal distribution of sensors can be used for estimating the direction of incoming waves through beamforming. Beamforming may be implemented as a phase-shifting and stacking of data recorded on the different sensors (i.e., conventional beamforming). Alternatively, beamforming can be applied to cross-correlations between the waveforms on the different sensors. We derive a kernel for beamforming cross-correlated data and call it cross-correlation beamforming (CCBF). We point out that CCBF has slightly better resolution and aliasing characteristics than conventional beamforming. When auto-correlations are added to CCBF, the array response functions are the same as for conventional beamforming. We show numerically that CCBF is more resilient to non-coherent noise. Furthermore, we illustrate that with CCBF individual receiver-pairs can be removed to improve mapping to the slowness domain. An additional flexibility of CCBF is that cross-correlations can be time-windowed prior to beamforming, e.g., to remove the directionality of a scattered wavefield. The observations on synthetic data are confirmed with field data from the SPITS array (Svalbard). Both when beamforming an earthquake arrival and when beamforming ambient noise, CCBF focuses more of the energy to a central beam. Overall, the main advantage of CCBF is noise suppression and its flexibility to remove station pairs that deteriorate the signal-related beampower.
Ordering dynamics in collectively swimming Surf Scoters.
Lukeman, Ryan
2014-08-21
One striking feature of collective motion in animal groups is a high degree of alignment among individuals, generating polarized motion. When order is lost, the dynamic process of reorganization, directly resulting from the individual interaction rules, provides significant information about both the nature of the rules, and how these rules affect the functioning of the collective. By analyzing trajectories of collectively swimming Surf Scoters (Melanitta perspicillata) during transitions between order and disorder, I find that individual speed and polarization are positively correlated in time, such that individuals move more slowly in groups exhibiting lower alignment. A previously validated zone-based model framework is used to specify interactions that permit repolarization while maintaining group cohesion and avoiding collisions. Polarization efficiency is optimized under the constraints of cohesion and collision-avoidance for alignment-dominated propulsion (versus autonomous propulsion), and for repulsion an order of magnitude larger than attraction and alignment. The relative strengths of interactions that optimize polarization also quantitatively recover the speed-polarization dependence observed in the data. Parameters determined here through optimizing polarization efficiency are essentially the same as those determined previously from a different approach: a best-fit model for polarized Surf Scoter movement data. The rules governing these flocks are therefore robust, accounting for behavior across a range of order and structure, and also highly responsive to perturbation. Flexibility and efficient repolarization offers an adaptive explanation for why specific interactions in such animal groups are used.
Sufficient symmetry conditions for Topological Quantum Order.
Nussinov, Zohar; Ortiz, Gerardo
2009-10-06
We prove sufficient conditions for Topological Quantum Order at zero and finite temperatures. The crux of the proof hinges on the existence of low-dimensional Gauge-Like Symmetries, thus providing a unifying framework based on a symmetry principle. These symmetries may be actual invariances of the system, or may emerge in the low-energy sector. Prominent examples of Topological Quantum Order display Gauge-Like Symmetries. New systems exhibiting such symmetries include Hamiltonians depicting orbital-dependent spin exchange and Jahn-Teller effects in transition metal orbital compounds, short-range frustrated Klein spin models, and p+ip superconducting arrays. We analyze the physical consequences of Gauge-Like Symmetries (including topological terms and charges) and show the insufficiency of the energy spectrum, topological entanglement entropy, maximal string correlators, and fractionalization in establishing Topological Quantum Order. General symmetry considerations illustrate that not withstanding spectral gaps, thermal fluctuations may impose restrictions on suggested quantum computing schemes. Our results allow us to go beyond standard topological field theories and engineer systems with Topological Quantum Order.
Birth order among homosexual men.
Zucker, Kenneth J; Blanchard, Ray; Siegelman, Marvin
2003-02-01
Nicolosi and Byrd in 2002 summarized empirical research on birth order and sexual orientation in men, which research has documented that homosexual men have a later birth order than heterosexual men. They did not, however, note a more refined analysis of an earlier null finding by Siegelman. This 1998 reanalysis by Blanchard, Zucker, Siegelman, Dickey, and Klassen also confirmed the later birth order of homosexual men.
Orientational order in disordered superconductors
Toner, J. )
1991-05-13
Orientational order in weakly pinned Abrikosov flux lattices is studied, taking into account two heretofore neglected effects: dislocations and orientational couplings to the underlying lattice. Without orientational couplings, arbitrarily weak pinning destroys long-ranged orientational order for all spatial dimensions {ital d}{lt}4. Orientational couplings stabilize long-ranged orientational order. For fields along an axis of {ital fourfold} symmetry, {ital sixfold} (hexatic) orientational order is described by a random-field Ising model, and so does not occur in {ital d}=2 (thin films) but does in {ital d}=3 (bulk).
NASA Astrophysics Data System (ADS)
Ziegler, A.; Metzler, A.; Köckenberger, W.; Izquierdo, M.; Komor, E.; Haase, A.; Décorps, M.; von Kienlin, M.
1996-08-01
Identification and quantitation in conventional1H spectroscopic imagingin vivois often hampered by the small chemical-shift range. To improve the spectral resolution of spectroscopic imaging, homonuclear two-dimensional correlation spectroscopy has been combined with phase encoding of the spatial dimensions. From the theoretical description of the coherence-transfer signal in the Fourier-transform domain, a comprehensive acquisition and processing strategy is presented that includes optimization of the width and the position of the acquisition windows, matched filtering of the signal envelope, and graphical presentation of the cross peak of interest. The procedure has been applied to image the spatial distribution of the correlation peaks from specific spin systems in the hypocotyl of castor bean (Ricinus communis) seedlings. Despite the overlap of many resonances, correlation-peak imaging made it possible to observe a number of proton resonances, such as those of sucrose, β-glucose, glutamine/glutamate, lysine, and arginine.
Rank order scaling of pictorial depth
van Doorn, Andrea; Koenderink, Jan; Wagemans, Johan
2011-01-01
We address the topic of “pictorial depth” in cases of pictures that are unlike photographic renderings. The most basic measure of “depth” is no doubt that of depth order. We establish depth order through the pairwise depth-comparison method, involving all pairs from a set of 49 fiducial points. The pictorial space for this study was evoked by a capriccio (imaginary landscape) by Francesco Guardi (1712–1793). In such a drawing pictorial space is suggested by the artist through a small set of conventional depth cues. As a result typical Western observers tend to agree largely in their visual awareness when looking at such art. We rank depths for locations that are not on a single surface and far apart in pictorial space. We find that observers resolve about 40 distinct depth layers and agree largely in this. From a previous experiment we have metrical data for the same observers. The rank correlations between the results are high. Perhaps surprisingly, we find no correlation between the number of distinct depth layers and the total metrical depth range. Thus, the relation between subjective magnitude and discrimination threshold fails to hold for pictorial depth. PMID:23145256
Morgan, Simon; Morgan, Andy; Kerr, Rohan; Tapley, Amanda; Magin, Parker
2016-01-01
Abstract Objective To assess the effectiveness of an educational intervention on test-ordering attitudes and intended practice of GP trainees, and any associations between changes in test ordering and trainee characteristics. Design Preworkshop and postworkshop survey of attitudes to test ordering, intended test-ordering practices for 3 clinical scenarios (fatigue, screening, and shoulder pain), and tolerance for uncertainty. Setting Three Australian regional general practice training providers. Participants General practice trainees (N = 167). Intervention A 2-hour workshop session and an online module. Main outcome measures Proportion of trainees who agreed with attitudinal statements before and after the workshop; proportion of trainees who would order tests, mean number of tests ordered, and number of appropriate and inappropriate tests ordered for each scenario before and after the workshop. Results Of 167 trainees, 132 (79.0%) completed both the preworkshop and postworkshop questionnaires. A total of 122 trainees attended the workshop. At baseline, 88.6% thought that tests can harm patients, 84.8% believed overtesting was a problem, 72.0% felt pressured by patients, 52.3% believed that tests would reassure patients, and 50.8% thought that they were less likely to be sued if they ordered tests. There were desirable changes in all attitudes after the workshop. Before the workshop, the mean number of tests that trainees would have ordered was 4.4, 4.8, and 1.5 for the fatigue, screening, and shoulder pain scenarios, respectively. After the workshop there were decreases in the mean number of both appropriate tests (decrease of 0.94) and inappropriate tests (decrease of 0.24) in the fatigue scenario; there was no change in the mean number of appropriate tests and a decrease in inappropriate tests (decrease of 0.76) in the screening scenario; and there was an increase in the proportion of trainees who would appropriately not order tests in the shoulder pain
TOPS optical correlation program
NASA Astrophysics Data System (ADS)
Lindell, Scott D.
1993-09-01
Martin Marietta is conducting a TOPS optical correlation program in which several algorithms and four optical correlators involving two spatial light modulator technologies will be developed and tested. The program will culminate in 1994 with an automatic target recognition flight demonstration using a UH-1 helicopter flying a Fiber Optic Guide Missile (FOG-M) mission profile. The flight demonstration will be conducted by US Army Missile Command (MICOM) and Martin Marietta and will involve detecting, locating and tracking a M60A2 tank positioned among an array of five vehicle types. Current status of the TOPS program will be given.
Correlation ion mobility spectroscopy
Pfeifer, Kent B.; Rohde, Steven B.
2008-08-26
Correlation ion mobility spectrometry (CIMS) uses gating modulation and correlation signal processing to improve IMS instrument performance. Closely spaced ion peaks can be resolved by adding discriminating codes to the gate and matched filtering for the received ion current signal, thereby improving sensitivity and resolution of an ion mobility spectrometer. CIMS can be used to improve the signal-to-noise ratio even for transient chemical samples. CIMS is especially advantageous for small geometry IMS drift tubes that can otherwise have poor resolution due to their small size.
Aquifer Denitrification: Is it a Zero-Order or First-Order Reaction?
NASA Astrophysics Data System (ADS)
Korom, S. F.
2007-12-01
Results from a network of 16 in situ mesocosms (ISMs) used to study aquifer denitrification at 5 sites in North Dakota and 4 sites in Minnesota (with 2 more installations planned for Iowa) are considered. At the Elk Valley aquifer (EVA) site in northeastern North Dakota, denitrification rates from six denitrification experiments were all better modeled as zero-order (0.16 +/- 0.05 mg nitrate-N/L/day), as determined by squared values of the linear correlation coefficient. Denitrification experiments at the other sites showed that denitrification was either below detection (< 0.01 mg nitrate-N/L/day) or was better modeled as a first-order reaction (0.00021/day to 0.0020/day), although squared values of the linear correlation coefficients for both rate models were nearly equal for some of the experiments. Not only were denitrification rates at the EVA site highest compared to the other sites in the ISM network, but sediment concentrations of electron donors at the EVA site were also greatest [ferrous iron about 0.3%, inorganic S (as pyrite) about 0.4%, organic C about 0.4%, weight basis]. These observations support the Michaelis- Menten model for reaction rates, which indicates that reaction rates will be zero-order when the substrate (electron donor) is abundant and first-order when the substrate availability is limited.
Tensor network states with three-site correlators
NASA Astrophysics Data System (ADS)
Kovyrshin, Arseny; Reiher, Markus
2016-11-01
We present a detailed analysis of various tensor network parameterizations within the complete graph tensor network states (CGTNS) approach. We extend our 2-site CGTNS scheme by introducing 3-site correlators. For this we devise three different strategies. The first relies solely on 3-site correlators and the second on 3-site correlators added on top of the 2-site correlator ansatz. To avoid an inflation of the variational space introduced by higher-order correlators, we limit the number of higher-order correlators to the most significant ones in the third strategy. Approaches for the selection of these most significant correlators are discussed. The sextet and doublet spin states of the spin-crossover complex manganocene serve as a numerical test case. In general, the CGTNS scheme achieves a remarkable accuracy for a significantly reduced size of the variational space. The advantages, drawbacks, and limitations of all CGTNS parameterizations investigated are rigorously discussed.
Long-range Order in Canary Song
Markowitz, Jeffrey E.; Ivie, Elizabeth; Kligler, Laura; Gardner, Timothy J.
2013-01-01
Bird songs range in form from the simple notes of a Chipping Sparrow to the rich performance of the nightingale. Non-adjacent correlations can be found in the syntax of some birdsongs, indicating that the choice of what to sing next is determined not only by the current syllable, but also by previous syllables sung. Here we examine the song of the domesticated canary, a complex singer whose song consists of syllables, grouped into phrases that are arranged in flexible sequences. Phrases are defined by a fundamental time-scale that is independent of the underlying syllable duration. We show that the ordering of phrases is governed by long-range rules: the choice of what phrase to sing next in a given context depends on the history of the song, and for some syllables, highly specific rules produce correlations in song over timescales of up to ten seconds. The neural basis of these long-range correlations may provide insight into how complex behaviors are assembled from more elementary, stereotyped modules. PMID:23658509
Long-range order in canary song.
Markowitz, Jeffrey E; Ivie, Elizabeth; Kligler, Laura; Gardner, Timothy J
2013-01-01
Bird songs range in form from the simple notes of a Chipping Sparrow to the rich performance of the nightingale. Non-adjacent correlations can be found in the syntax of some birdsongs, indicating that the choice of what to sing next is determined not only by the current syllable, but also by previous syllables sung. Here we examine the song of the domesticated canary, a complex singer whose song consists of syllables, grouped into phrases that are arranged in flexible sequences. Phrases are defined by a fundamental time-scale that is independent of the underlying syllable duration. We show that the ordering of phrases is governed by long-range rules: the choice of what phrase to sing next in a given context depends on the history of the song, and for some syllables, highly specific rules produce correlations in song over timescales of up to ten seconds. The neural basis of these long-range correlations may provide insight into how complex behaviors are assembled from more elementary, stereotyped modules.
High-Order/Low-Order methods for ocean modeling
Newman, Christopher; Womeldorff, Geoff; Chacón, Luis; Knoll, Dana A.
2015-06-01
We examine a High Order/Low Order (HOLO) approach for a z-level ocean model and show that the traditional semi-implicit and split-explicit methods, as well as a recent preconditioning strategy, can easily be cast in the framework of HOLO methods. The HOLO formulation admits an implicit-explicit method that is algorithmically scalable and second-order accurate, allowing timesteps much larger than the barotropic time scale. We demonstrate how HOLO approaches, in particular the implicit-explicit method, can provide a solid route for ocean simulation to heterogeneous computing and exascale environments.
Problem Order Implications for Learning
ERIC Educational Resources Information Center
Li, Nan; Cohen, William W.; Koedinger, Kenneth R.
2013-01-01
The order of problems presented to students is an important variable that affects learning effectiveness. Previous studies have shown that solving problems in a blocked order, in which all problems of one type are completed before the student is switched to the next problem type, results in less effective performance than does solving the problems…
The Polyakov loop correlator at NNLO and singlet and octet correlators
Ghiglieri, Jacopo
2011-05-23
We present the complete next-to-next-to-leading-order calculation of the correlation function of two Polyakov loops for temperatures smaller than the inverse distance between the loops and larger than the Coulomb potential. We discuss the relationship of this correlator with the singlet and octet potentials which we obtain in an Effective Field Theory framework based on finite-temperature potential Non-Relativistic QCD, showing that the Polyakov loop correlator can be re-expressed, at the leading order in a multipole expansion, as a sum of singlet and octet contributions. We also revisit the calculation of the expectation value of the Polyakov loop at next-to-next-to-leading order.
Electrophysiological correlates of change detection.
Eimer, Martin; Mazza, Veronica
2005-05-01
To identify electrophysiological correlates of change detection, event-related brain potentials (ERPs) were recorded while participants monitored displays containing four faces in order to detect a face identity change across successive displays. Successful change detection was mirrored by an N2pc component at posterior electrodes contralateral to the side of a change, suggesting close links between conscious change detection and attention. ERPs on undetected-change trials differed from detected-change and no-change trials. We suggest that short-latency ERP differences between these trial types reflect trial-by-trial fluctuations in advance task preparation, whereas differences in the P3 time range are due to variations in the duration of perceptual and decision-related processing. Overall, these findings demonstrate that ERPs are a useful tool for dissociating processes underlying change blindness and change detection.
First and Higher Order Effects on Zero Order Radiative Transfer Model
NASA Astrophysics Data System (ADS)
Neelam, M.; Mohanty, B.
2014-12-01
Microwave radiative transfer model are valuable tool in understanding the complex land surface interactions. Past literature has largely focused on local sensitivity analysis for factor priotization and ignoring the interactions between the variables and uncertainties around them. Since land surface interactions are largely nonlinear, there always exist uncertainties, heterogeneities and interactions thus it is important to quantify them to draw accurate conclusions. In this effort, we used global sensitivity analysis to address the issues of variable uncertainty, higher order interactions, factor priotization and factor fixing for zero-order radiative transfer (ZRT) model. With the to-be-launched Soil Moisture Active Passive (SMAP) mission of NASA, it is very important to have a complete understanding of ZRT for soil moisture retrieval to direct future research and cal/val field campaigns. This is a first attempt to use GSA technique to quantify first order and higher order effects on brightness temperature from ZRT model. Our analyses reflect conditions observed during the growing agricultural season for corn and soybeans in two different regions in - Iowa, U.S.A and Winnipeg, Canada. We found that for corn fields in Iowa, there exist significant second order interactions between soil moisture, surface roughness parameters (RMS height and correlation length) and vegetation parameters (vegetation water content, structure and scattering albedo), whereas in Winnipeg, second order interactions are mainly due to soil moisture and vegetation parameters. But for soybean fields in both Iowa and Winnipeg, we found significant interactions only to exist between soil moisture and surface roughness parameters.
Magnetic order driven by orbital ordering in the semiconducting KFe1.5Se2
NASA Astrophysics Data System (ADS)
Jiang, Qing; Yao, Dao-Xin
2016-04-01
The two-orbital Hubbard model is studied numerically by using the Hartree-Fock approximation in both real space and momentum space, and the ground-state properties of the alkali metal iron selenide semiconducting KFe1.5Se2 are investigated. A rhombus-type Fe vacancy order with stripetype antiferromagnetic (AFM) order is found, as was observed in neutron scattering experiments [J. Zhao, et al., Phys. Rev. Lett. 109, 267003 (2012)]. Hopping parameters are obtained by fitting the experimentally observed stripe AFM phase in real space. These hopping parameters are then used to study the ground-state properties of the semiconductor in momentum space. It is found to be a strongly correlated system with a large on-site Coulomb repulsion U, similar to the AFM Mott insulator — the parent compound of copper oxide superconductors. We also find that the electronic occupation numbers and magnetizations in the d xz and d yz orbitals become different simultaneously when U > U c (˜3.4 eV), indicating orbital ordering. These results imply that the rotational symmetry between the two orbitals is broken by orbital ordering and thus drives the strong anisotropy of the magnetic coupling that has been observed by experiments and that the stripe-type AFM order in this compound may be caused by orbital ordering together with the observed large anisotropy.
Electromagnetic nonuniformly correlated beams.
Tong, Zhisong; Korotkova, Olga
2012-10-01
A class of electromagnetic sources with nonuniformly distributed field correlations is introduced. The conditions on source parameters guaranteeing that the source generates a physical beam are derived. It is shown that the new sources are capable of producing beams with polarization properties that evolve on propagation in a manner much more complex compared to the well-known electromagnetic Gaussian Schell-model beams.
Neuroanatomical Correlates of Intelligence
ERIC Educational Resources Information Center
Luders, Eileen; Narr, Katherine L.; Thompson, Paul M.; Toga, Arthur W.
2009-01-01
With the advancement of image acquisition and analysis methods in recent decades, unique opportunities have emerged to study the neuroanatomical correlates of intelligence. Traditional approaches examining global measures have been complemented by insights from more regional analyses based on pre-defined areas. Newer state-of-the-art approaches…
Nonverbal Correlates of Anxiety.
ERIC Educational Resources Information Center
Eckman, Bruce K.
Twenty college age males' hand shrugs, face-play manipulations, and frequency and duration of mutual eye contact were recorded in response to a female counterpart who varied her assertiveness and attractiveness in a two by two factorial design. Mutual eye contact, which increased under attractive conditions, was a useful negative correlate of…
NASA Astrophysics Data System (ADS)
Hartman, Richard L.; Farr, Keith B.; McColgan, Michele W.; Smith, Ralph G.
1997-03-01
This paper discusses an optical correlator interfaces to a FLIR and laser rangefinder to aid aircraft landing aboard an aircraft carrier. The purpose was to recognize aircraft and provide precision track in spite of the engine plume which is visible in IR images. Toward the end of the program, an opportunity arose to piggyback on tests of a Navy FLIR system, on board the USS Enterprise. The Navy's developmental FLIR and laser rangefinder were mounted on the carrier and provided excellent imagery with concurrent range data. The correlator performed a limited set of experiments at sea, tracking an aircraft from 8000 feet until almost touchdown. The challenges to the correlator we operation in a harsh environment and real time interfacing with other hardware. Real time range information controlled a series of filters in the correlator. The system fit into a standard panel rack and utilized remote alignment. The system operated during the chock of aircraft launch and landing, with no need to open up the optical box.
Correlated Attack Modeling (CAM)
2003-10-01
eywell’s Scyllarus correlation framework [18], and a simulated-annealing-based approach for detecting stealthy portscans [35]. For detecting multistep...California, May 12–15, 2002. [35] S. Staniford, J. A. Hoagland, and J. M. McAlerney. Practical automated detection of stealthy portscans . Journal of
ERIC Educational Resources Information Center
Matthews, Doris B.
As part of a continuing series of research studies on stress in schools, this study examined the construct validity of peripheral temperature at the fingertips as a measure of school stress. Measurements were made in classes selected at random from 11 volunteer schools in South Carolina. Three types of correlational studies were undertaken: (1)…
Operon Gene Order Is Optimized for Ordered Protein Complex Assembly.
Wells, Jonathan N; Bergendahl, L Therese; Marsh, Joseph A
2016-02-02
The assembly of heteromeric protein complexes is an inherently stochastic process in which multiple genes are expressed separately into proteins, which must then somehow find each other within the cell. Here, we considered one of the ways by which prokaryotic organisms have attempted to maximize the efficiency of protein complex assembly: the organization of subunit-encoding genes into operons. Using structure-based assembly predictions, we show that operon gene order has been optimized to match the order in which protein subunits assemble. Exceptions to this are almost entirely highly expressed proteins for which assembly is less stochastic and for which precisely ordered translation offers less benefit. Overall, these results show that ordered protein complex assembly pathways are of significant biological importance and represent a major evolutionary constraint on operon gene organization.
NASA Astrophysics Data System (ADS)
Shankaraiah, N.; Dubey, Awadhesh K.; Puri, Sanjay; Shenoy, Subodh R.
2016-12-01
In the conceptual framework of phase ordering after temperature quenches below transition, we consider the underdamped Bales-Gooding-type "momentum conserving" dynamics of a 2D martensitic structural transition from a square-to-rectangle unit cell. The one-component or NOP=1 order parameter is one of the physical strains, and the Landau free energy has a triple well, describing a first-order transition. We numerically study the evolution of the strain-strain correlation, and find that it exhibits dynamical scaling, with a coarsening length L (t ) ˜tα . We find at intermediate and long times that the coarsening exponent sequentially takes on respective values close to α =2 /3 and 1 /2 . For deep quenches, the coarsening can be arrested at long times, with α ≃0 . These exponents are also found in 3D. To understand such behavior, we insert a dynamical-scaling ansatz into the correlation function dynamics to give, at a dominant scaled separation, a nonlinear kinetics of the curvature g (t )≡1 /L (t ) . The curvature solutions have time windows of power-law decays g ˜1 /tα , with exponent values α matching simulations, and manifestly independent of spatial dimension. Applying this curvature-kinetics method to mass-conserving Cahn-Hilliard dynamics for a double-well Landau potential in a scalar NOP=1 order parameter yields exponents α =1 /4 and 1 /3 for intermediate and long times. For vector order parameters with NOP≥2 , the exponents are α =1 /4 only, consistent with previous work. The curvature kinetics method could be useful in extracting coarsening exponents for other phase-ordering dynamics.
Dipolar correlations in liquid water
Zhang, Cui; Galli, Giulia
2014-08-28
We present an analysis of the dipolar correlations in water as a function of temperature and density and in the presence of simple ionic solutes, carried out using molecular dynamics simulations and empirical potentials. We show that the dipole-dipole correlation function of the liquid exhibits sizable oscillations over nanodomains of about 1.5 nm radius, with several isosbestic points as a function of temperature; the size of the nanodomains is nearly independent on temperature and density, between 240 and 400 K and 0.9 and 1.3 g/cm{sup 3}, but it is substantially affected by the presence of solvated ions. In the same range of thermodynamic conditions, the decay time (τ) of the system dipole moment varies by a factor of about 30 and 1.5, as a function of temperature and density, respectively. At 300 K, we observed a maximum in τ as a function of density, and a corresponding shallow maximum in the tetrahedral order parameter, in a range where the diffusion coefficient, the pressure and the dielectric constant increase monotonically.
Fiducial marker for correlating images
Miller, Lisa Marie; Smith, Randy J.; Warren, John B.; Elliott, Donald
2011-06-21
The invention relates to a fiducial marker having a marking grid that is used to correlate and view images produced by different imaging modalities or different imaging and viewing modalities. More specifically, the invention relates to the fiducial marking grid that has a grid pattern for producing either a viewing image and/or a first analytical image that can be overlaid with at least one other second analytical image in order to view a light path or to image different imaging modalities. Depending on the analysis, the grid pattern has a single layer of a certain thickness or at least two layers of certain thicknesses. In either case, the grid pattern is imageable by each imaging or viewing modality used in the analysis. Further, when viewing a light path, the light path of the analytical modality cannot be visualized by viewing modality (e.g., a light microscope objective). By correlating these images, the ability to analyze a thin sample that is, for example, biological in nature but yet contains trace metal ions is enhanced. Specifically, it is desired to analyze both the organic matter of the biological sample and the trace metal ions contained within the biological sample without adding or using extrinsic labels or stains.
Computational correlates of consciousness.
Cleeremans, Axel
2005-01-01
Over the past few years numerous proposals have appeared that attempt to characterize consciousness in terms of what could be called its computational correlates: Principles of information processing with which to characterize the differences between conscious and unconscious processing. Proposed computational correlates include architectural specialization (such as the involvement of specific regions of the brain in conscious processing), properties of representations (such as their stability in time or their strength), and properties of specific processes (such as resonance, synchrony, interactivity, or information integration). In exactly the same way as one can engage in a search for the neural correlates of consciousness, one can thus search for the computational correlates of consciousness. The most direct way of doing is to contrast models of conscious versus unconscious information processing. In this paper, I review these developments and illustrate how computational modeling of specific cognitive processes can be useful in exploring and in formulating putative computational principles through which to capture the differences between conscious and unconscious cognition. What can be gained from such approaches to the problem of consciousness is an understanding of the function it plays in information processing and of the mechanisms that subtend it. Here, I suggest that the central function of consciousness is to make it possible for cognitive agents to exert flexible, adaptive control over behavior. From this perspective, consciousness is best characterized as involving (1) a graded continuum defined over quality of representation, such that availability to consciousness and to cognitive control correlates with properties of representation, and (2) the implication of systems of meta-representations.
Code of Federal Regulations, 2013 CFR
2013-01-01
... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE PROCESSED RASPBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Processed Raspberry Promotion, Research, and Information Order Definitions § 1208.14 Order. Order means the Processed Raspberry Promotion, Research, and Information Order....
Code of Federal Regulations, 2014 CFR
2014-01-01
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Nonlocal order parameters for the 1D Hubbard model.
Montorsi, Arianna; Roncaglia, Marco
2012-12-07
We characterize the Mott-insulator and Luther-Emery phases of the 1D Hubbard model through correlators that measure the parity of spin and charge strings along the chain. These nonlocal quantities order in the corresponding gapped phases and vanish at the critical point U(c)=0, thus configuring as hidden order parameters. The Mott insulator consists of bound doublon-holon pairs, which in the Luther-Emery phase turn into electron pairs with opposite spins, both unbinding at U(c). The behavior of the parity correlators is captured by an effective free spinless fermion model.
Nonlocal Order Parameters for the 1D Hubbard Model
NASA Astrophysics Data System (ADS)
Montorsi, Arianna; Roncaglia, Marco
2012-12-01
We characterize the Mott-insulator and Luther-Emery phases of the 1D Hubbard model through correlators that measure the parity of spin and charge strings along the chain. These nonlocal quantities order in the corresponding gapped phases and vanish at the critical point Uc=0, thus configuring as hidden order parameters. The Mott insulator consists of bound doublon-holon pairs, which in the Luther-Emery phase turn into electron pairs with opposite spins, both unbinding at Uc. The behavior of the parity correlators is captured by an effective free spinless fermion model.
Correlative weighted stacking for seismic data in the wavelet domain
Zhang, S.; Xu, Y.; Xia, J.; ,
2004-01-01
Horizontal stacking plays a crucial role for modern seismic data processing, for it not only compresses random noise and multiple reflections, but also provides a foundational data for subsequent migration and inversion. However, a number of examples showed that random noise in adjacent traces exhibits correlation and coherence. The average stacking and weighted stacking based on the conventional correlative function all result in false events, which are caused by noise. Wavelet transform and high order statistics are very useful methods for modern signal processing. The multiresolution analysis in wavelet theory can decompose signal on difference scales, and high order correlative function can inhibit correlative noise, for which the conventional correlative function is of no use. Based on the theory of wavelet transform and high order statistics, high order correlative weighted stacking (HOCWS) technique is presented in this paper. Its essence is to stack common midpoint gathers after the normal moveout correction by weight that is calculated through high order correlative statistics in the wavelet domain. Synthetic examples demonstrate its advantages in improving the signal to noise (S/N) ration and compressing the correlative random noise.
The Meaning of Higher-Order Factors in Reflective-Measurement Models
ERIC Educational Resources Information Center
Eid, Michael; Koch, Tobias
2014-01-01
Higher-order factor analysis is a widely used approach for analyzing the structure of a multidimensional test. Whenever first-order factors are correlated researchers are tempted to apply a higher-order factor model. But is this reasonable? What do the higher-order factors measure? What is their meaning? Willoughby, Holochwost, Blanton, and Blair…
From micro-correlations to macro-correlations
NASA Astrophysics Data System (ADS)
Eliazar, Iddo
2016-11-01
Random vectors with a symmetric correlation structure share a common value of pair-wise correlation between their different components. The symmetric correlation structure appears in a multitude of settings, e.g. mixture models. In a mixture model the components of the random vector are drawn independently from a general probability distribution that is determined by an underlying parameter, and the parameter itself is randomized. In this paper we study the overall correlation of high-dimensional random vectors with a symmetric correlation structure. Considering such a random vector, and terming its pair-wise correlation "micro-correlation", we use an asymptotic analysis to derive the random vector's "macro-correlation" : a score that takes values in the unit interval, and that quantifies the random vector's overall correlation. The method of obtaining macro-correlations from micro-correlations is then applied to a diverse collection of frameworks that demonstrate the method's wide applicability.
Multiple order common path spectrometer
NASA Technical Reports Server (NTRS)
Newbury, Amy B. (Inventor)
2010-01-01
The present invention relates to a dispersive spectrometer. The spectrometer allows detection of multiple orders of light on a single focal plane array by splitting the orders spatially using a dichroic assembly. A conventional dispersion mechanism such as a defraction grating disperses the light spectrally. As a result, multiple wavelength orders can be imaged on a single focal plane array of limited spectral extent, doubling (or more) the number of spectral channels as compared to a conventional spectrometer. In addition, this is achieved in a common path device.
Complex higher order derivative theories
Margalli, Carlos A.; Vergara, J. David
2012-08-24
In this work is considered a complex scalar field theory with higher order derivative terms and interactions. A procedure is developed to quantize consistently this system avoiding the presence of negative norm states. In order to achieve this goal the original real scalar high order field theory is extended to a complex space attaching a complex total derivative to the theory. Next, by imposing reality conditions the complex theory is mapped to a pair of interacting real scalar field theories without the presence of higher derivative terms.
Collective Behaviour without Collective Order in Wild Swarms of Midges
Attanasi, Alessandro; Cavagna, Andrea; Del Castello, Lorenzo; Giardina, Irene; Melillo, Stefania; Parisi, Leonardo; Pohl, Oliver; Rossaro, Bruno; Shen, Edward; Silvestri, Edmondo; Viale, Massimiliano
2014-01-01
Collective behaviour is a widespread phenomenon in biology, cutting through a huge span of scales, from cell colonies up to bird flocks and fish schools. The most prominent trait of collective behaviour is the emergence of global order: individuals synchronize their states, giving the stunning impression that the group behaves as one. In many biological systems, though, it is unclear whether global order is present. A paradigmatic case is that of insect swarms, whose erratic movements seem to suggest that group formation is a mere epiphenomenon of the independent interaction of each individual with an external landmark. In these cases, whether or not the group behaves truly collectively is debated. Here, we experimentally study swarms of midges in the field and measure how much the change of direction of one midge affects that of other individuals. We discover that, despite the lack of collective order, swarms display very strong correlations, totally incompatible with models of non-interacting particles. We find that correlation increases sharply with the swarm's density, indicating that the interaction between midges is based on a metric perception mechanism. By means of numerical simulations we demonstrate that such growing correlation is typical of a system close to an ordering transition. Our findings suggest that correlation, rather than order, is the true hallmark of collective behaviour in biological systems. PMID:25057853
EARLINET Correlative Measurements For CALIPSO
NASA Astrophysics Data System (ADS)
Pappalardo, G.
2006-12-01
EARLINET, the European Aerosol Research Lidar Network, is the first aerosol lidar network, established in 2000, with the main goal to provide a comprehensive, quantitative, and statistically significant data base for the aerosol distribution on a continental scale. At present, 24 stations distributed over Europe are part of the network: 10 single backscatter lidar stations, 7 Raman lidar stations with the Raman channel in the UV for independent measurements of aerosol extinction and backscatter, and 7 multi-wavelength Raman lidar stations (elastic channel at 1064 nm, 532 nm, 355 nm, Raman channels at 532 nm and 355 nm, plus depolarization channel at 532 nm) for the retrieval of aerosol microphysical properties. The network activity is based on scheduled measurements, a rigorous quality assurance program addressing both instruments and evaluation algorithms, and a standardized data exchange format. In order to collect unbiased data, all the network stations perform measurements simultaneously at three fixed dates a week. Lidar observations are performed on a regular schedule of one daytime measurement on Monday around noon, when the boundary layer is usually well developed, and two night time measurements per week (Monday and Thursday), with low background light, in order to perform Raman extinction measurements. Additional network measurements are performed to address specifically important processes that are localized either in space or time, like Saharan dust outbreaks, forest fires, volcanic eruptions, photochemical smog. EARLINET represents an optimal tool to validate CALIPSO lidar data and to provide the necessary information to fully exploit the information from that mission. In particular, aerosol extinction measurements, provided by the network, will be important for the aerosol retrievals from the CALIPSO backscatter lidar. EARLINET started correlative measurements for CALIPSO since 14 June 2006. These EARLINET correlative measurements are performed at
Code of Federal Regulations, 2013 CFR
2013-01-01
... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....
Code of Federal Regulations, 2011 CFR
2011-01-01
... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....
Code of Federal Regulations, 2012 CFR
2012-01-01
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2010-01-01
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Code of Federal Regulations, 2014 CFR
2014-01-01
... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE BLUEBERRY PROMOTION, RESEARCH, AND INFORMATION ORDER Blueberry Promotion, Research, and Information Order Definitions § 1218.12 Order....
Code of Federal Regulations, 2012 CFR
2012-01-01
... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order means an...
Code of Federal Regulations, 2011 CFR
2011-01-01
... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order means an...
Code of Federal Regulations, 2010 CFR
2010-01-01
... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order means an...
Code of Federal Regulations, 2014 CFR
2014-01-01
... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order means an...
Code of Federal Regulations, 2013 CFR
2013-01-01
... AND ORDERS; MISCELLANEOUS COMMODITIES), DEPARTMENT OF AGRICULTURE MANGO PROMOTION, RESEARCH, AND INFORMATION Mango Promotion, Research, and Information Order Definitions § 1206.13 Order. Order means an...
Testing Consent Order for Octamethylcyclotetrasiloxane
This rule announces that EPA has signed an enforceable testing consent order with six manufacturers of octamethylcyclotetrasiloxane (OMCTS; CAS No. 556-67—2, who have agreed to perform certain chemical fate and environmental effects tests with OMCTS.
ERIC Educational Resources Information Center
Glasser, L.
1989-01-01
The evolution of ideas about the concept of chaos is surveyed. Discussed are chaos in deterministic, dynamic systems; order in dissipative systems; and thermodynamics and irreversibility. Included are logistic and bifurcation maps to illustrate points made in the discussion. (CW)
NASA Astrophysics Data System (ADS)
Elliott, Robert J.; Richards, W. Graham
A method for obtaining precise charge densities in defined regions of space from ab initio molecular wavefunctions is employed to place the concept of bond order on a firm theoretical footing. The bond orders obtained for carbon—carbon bonds in a range of organic compounds are assessed: those for buta-1,3-diene confirm that it consists of essentially localised double and single bonds.
Correlators in nontrivial backgrounds
Mello Koch, Robert de; Ives, Norman; Stephanou, Michael
2009-01-15
Operators in N=4 super Yang-Mills theory with an R-charge of O(N{sup 2}) are dual to backgrounds which are asymtotically AdS{sub 5}xS{sup 5}. In this article we develop efficient techniques that allow the computation of correlation functions in these backgrounds. We find that (i) contractions between fields in the string words and fields in the operator creating the background are the field theory accounting of the new geometry, (ii) correlation functions of probes in these backgrounds are given by the free field theory contractions but with rescaled propagators and (iii) in these backgrounds there are no open string excitations with their special end point interactions; we have only closed string excitations.
Correlations and Ostwald ripening
NASA Technical Reports Server (NTRS)
Marder, M.
1987-01-01
A previously developed model (Weins and Cahn, 1973) describing the growth of spheres of a second phase in metal alloys (Ostwald coarsening) is slightly modified to make it possible to study the complete time evolution of the system rather than simply the late-stage scaling behavior. Closed equations are obtained which describe the time evolution of two-particle correlations in the system. The development of the correlations is analyzed, and simpler expressions are found and solved numerically. The results are compared with experimental data for different systems (e.g., Ni-Al, Ni-Cr-Al, Co-Ni-Cr-Ti, Cu-Co, and MgO-Fe), alternate methods, and existing theories.
Complete normal ordering 1: Foundations
NASA Astrophysics Data System (ADS)
Ellis, John; Mavromatos, Nick E.; Skliros, Dimitri P.
2016-08-01
We introduce a new prescription for quantising scalar field theories (in generic spacetime dimension and background) perturbatively around a true minimum of the full quantum effective action, which is to 'complete normal order' the bare action of interest. When the true vacuum of the theory is located at zero field value, the key property of this prescription is the automatic cancellation, to any finite order in perturbation theory, of all tadpole and, more generally, all 'cephalopod' Feynman diagrams. The latter are connected diagrams that can be disconnected into two pieces by cutting one internal vertex, with either one or both pieces free from external lines. In addition, this procedure of 'complete normal ordering' (which is an extension of the standard field theory definition of normal ordering) reduces by a substantial factor the number of Feynman diagrams to be calculated at any given loop order. We illustrate explicitly the complete normal ordering procedure and the cancellation of cephalopod diagrams in scalar field theories with non-derivative interactions, and by using a point splitting 'trick' we extend this result to theories with derivative interactions, such as those appearing as non-linear σ-models in the world-sheet formulation of string theory. We focus here on theories with trivial vacua, generalising the discussion to non-trivial vacua in a follow-up paper.
Semiclassical approximations to quantum time correlation functions
NASA Astrophysics Data System (ADS)
Egorov, S. A.; Skinner, J. L.
1998-09-01
Over the last 40 years several ad hoc semiclassical approaches have been developed in order to obtain approximate quantum time correlation functions, using as input only the corresponding classical time correlation functions. The accuracy of these approaches has been tested for several exactly solvable gas-phase models. In this paper we test the accuracy of these approaches by comparing to an exactly solvable many-body condensed-phase model. We show that in the frequency domain the Egelstaff approach is the most accurate, especially at high frequencies, while in the time domain one of the other approaches is more accurate.
Charge Correlations in Plasma Line Broadening
Wrighton, Jeffrey M.; Dufty, James W.
2008-10-22
The traditional theory of plasma line broadening is re-examined to correct for phenom-enological assumptions regarding charge correlations. Conditions for static ions are assumed, and the ion microfield distribution is introduced without neglecting ion-electron correlations, and with a precise definition for the ion field at the radiator. Radiator and plasma subsystems are defined so as to make a second order calculation of electron broadening valid for the case of high Z radiators. The electron broadening operator is identified in terms of the fluctuation of the electron density at the radiator, averaged over the entire plasma constrained by a given value for the ion microfield.
Correlations between corneal and total wavefront aberrations
NASA Astrophysics Data System (ADS)
Mrochen, Michael; Jankov, Mirko; Bueeler, Michael; Seiler, Theo
2002-06-01
Purpose: Corneal topography data expressed as corneal aberrations are frequently used to report corneal laser surgery results. However, the optical image quality at the retina depends on all optical elements of the eye such as the human lens. Thus, the aim of this study was to investigate the correlations between the corneal and total wavefront aberrations and to discuss the importance of corneal aberrations for representing corneal laser surgery results. Methods: Thirty three eyes of 22 myopic subjects were measured with a corneal topography system and a Tschernig-type wavefront analyzer after the pupils were dilated to at least 6 mm in diameter. All measurements were centered with respect to the line of sight. Corneal and total wavefront aberrations were calculated up to the 6th Zernike order in the same reference plane. Results: Statistically significant correlations (p < 0.05) between the corneal and total wavefront aberrations were found for the astigmatism (C3,C5) and all 3rd Zernike order coefficients such as coma (C7,C8). No statistically significant correlations were found for all 4th to 6th order Zernike coefficients except for the 5th order horizontal coma C18 (p equals 0.003). On average, all Zernike coefficients for the corneal aberrations were found to be larger compared to Zernike coefficients for the total wavefront aberrations. Conclusions: Corneal aberrations are only of limited use for representing the optical quality of the human eye after corneal laser surgery. This is due to the lack of correlation between corneal and total wavefront aberrations in most of the higher order aberrations. Besides this, the data present in this study yield towards an aberration balancing between corneal aberrations and the optical elements within the eye that reduces the aberration from the cornea by a certain degree. Consequently, ideal customized ablations have to take both, corneal and total wavefront aberrations, into consideration.
Neural correlates of gratitude.
Fox, Glenn R; Kaplan, Jonas; Damasio, Hanna; Damasio, Antonio
2015-01-01
Gratitude is an important aspect of human sociality, and is valued by religions and moral philosophies. It has been established that gratitude leads to benefits for both mental health and interpersonal relationships. It is thus important to elucidate the neurobiological correlates of gratitude, which are only now beginning to be investigated. To this end, we conducted an experiment during which we induced gratitude in participants while they underwent functional magnetic resonance imaging. We hypothesized that gratitude ratings would correlate with activity in brain regions associated with moral cognition, value judgment and theory of mind. The stimuli used to elicit gratitude were drawn from stories of survivors of the Holocaust, as many survivors report being sheltered by strangers or receiving lifesaving food and clothing, and having strong feelings of gratitude for such gifts. The participants were asked to place themselves in the context of the Holocaust and imagine what their own experience would feel like if they received such gifts. For each gift, they rated how grateful they felt. The results revealed that ratings of gratitude correlated with brain activity in the anterior cingulate cortex and medial prefrontal cortex, in support of our hypotheses. The results provide a window into the brain circuitry for moral cognition and positive emotion that accompanies the experience of benefitting from the goodwill of others.
2013-08-02
CorAL is a software Library designed to aid in the analysis of femtoscipic data. Femtoscopic data are a class of measured quantities used in heavy-ion collisions to characterize particle emitting source sizes. The most common type of this data is two-particle correleations induced by the Hanbury-Brown/Twiss (HBT) Effect, but can also include correlations induced by final-state interactions between pairs of emitted particles in a heavy-ion collision. Because heavy-ion collisions are complex many particle systems, modeling hydrodynamical models or hybrid techniques. Using the CRAB module, CorAL can turn the output from these models into something that can be directley compared to experimental data. CorAL can also take the raw experimentally measured correlation functions and image them by inverting the Koonin-Pratt equation to extract the space-time emission profile of the particle emitting source. This source function can be further analyzed or directly compared to theoretical calculations.
NASA Astrophysics Data System (ADS)
Schaaf, Kjeld; Overeem, Ruud
2004-06-01
Moore’s law is best exploited by using consumer market hardware. In particular, the gaming industry pushes the limit of processor performance thus reducing the cost per raw flop even faster than Moore’s law predicts. Next to the cost benefits of Common-Of-The-Shelf (COTS) processing resources, there is a rapidly growing experience pool in cluster based processing. The typical Beowulf cluster of PC’s supercomputers are well known. Multiple examples exists of specialised cluster computers based on more advanced server nodes or even gaming stations. All these cluster machines build upon the same knowledge about cluster software management, scheduling, middleware libraries and mathematical libraries. In this study, we have integrated COTS processing resources and cluster nodes into a very high performance processing platform suitable for streaming data applications, in particular to implement a correlator. The required processing power for the correlator in modern radio telescopes is in the range of the larger supercomputers, which motivates the usage of supercomputer technology. Raw processing power is provided by graphical processors and is combined with an Infiniband host bus adapter with integrated data stream handling logic. With this processing platform a scalable correlator can be built with continuously growing processing power at consumer market prices.
Neural correlates of gratitude
Fox, Glenn R.; Kaplan, Jonas; Damasio, Hanna; Damasio, Antonio
2015-01-01
Gratitude is an important aspect of human sociality, and is valued by religions and moral philosophies. It has been established that gratitude leads to benefits for both mental health and interpersonal relationships. It is thus important to elucidate the neurobiological correlates of gratitude, which are only now beginning to be investigated. To this end, we conducted an experiment during which we induced gratitude in participants while they underwent functional magnetic resonance imaging. We hypothesized that gratitude ratings would correlate with activity in brain regions associated with moral cognition, value judgment and theory of mind. The stimuli used to elicit gratitude were drawn from stories of survivors of the Holocaust, as many survivors report being sheltered by strangers or receiving lifesaving food and clothing, and having strong feelings of gratitude for such gifts. The participants were asked to place themselves in the context of the Holocaust and imagine what their own experience would feel like if they received such gifts. For each gift, they rated how grateful they felt. The results revealed that ratings of gratitude correlated with brain activity in the anterior cingulate cortex and medial prefrontal cortex, in support of our hypotheses. The results provide a window into the brain circuitry for moral cognition and positive emotion that accompanies the experience of benefitting from the goodwill of others. PMID:26483740
Interpreting correlations in biosequences
NASA Astrophysics Data System (ADS)
Herzel, H.; Trifonov, E. N.; Weiss, O.; Große, I.
Understanding the complex organization of genomes as well as predicting the location of genes and the possible structure of the gene products are some of the most important problems in current molecular biology. Many statistical techniques are used to address these issues. A central role among them play correlation functions. This paper is based on an analysis of the decay of the entire 4×4 dimensional covariance matrix of DNA sequences. We apply this covariance analysis to human chromosomal regions, yeast DNA, and bacterial genomes and interpret the three most pronounced statistical features - long-range correlations, a period 3, and a period 10-11 - using known biological facts about the structure of genomes. For example, we relate the slowly decaying long-range G+C correlations to dispersed repeats and CpG islands. We show quantitatively that the 3-basepair-periodicity is due to the nonuniformity of the codon usage in protein coding segments. We finally show that periodicities of 10-11 basepairs in yeast DNA originate from an alternation of hydrophobic and hydrophilic amino acids in protein sequences.
Theory of correlations in stochastic neural networks
NASA Astrophysics Data System (ADS)
Ginzburg, Iris; Sompolinsky, Haim
1994-10-01
One of the main experimental tools in probing the interactions between neurons has been the measurement of the correlations in their activity. In general, however, the interpretation of the observed correlations is difficult since the correlation between a pair of neurons is influenced not only by the direct interaction between them but also by the dynamic state of the entire network to which they belong. Thus a comparison between the observed correlations and the predictions from specific model networks is needed. In this paper we develop a theory of neuronal correlation functions in large networks comprising several highly connected subpopulations and obeying stochastic dynamic rules. When the networks are in asynchronous states, the cross correlations are relatively weak, i.e., their amplitude relative to that of the autocorrelations is of order of 1/N, N being the size of the interacting populations. Using the weakness of the cross correlations, general equations that express the matrix of cross correlations in terms of the mean neuronal activities and the effective interaction matrix are presented. The effective interactions are the synaptic efficacies multiplied by the gain of the postsynaptic neurons. The time-delayed cross-correlation matrix can be expressed as a sum of exponentially decaying modes that correspond to the (nonorthogonal) eigenvectors of the effective interaction matrix. The theory is extended to networks with random connectivity, such as randomly dilute networks. This allows for a comparison between the contribution from the internal common input and that from the direct interactions to the correlations of monosynaptically coupled pairs. A closely related quantity is the linear response of the neurons to external time-dependent perturbations. We derive the form of the dynamic linear response function of neurons in the above architecture in terms of the eigenmodes of the effective interaction matrix. The behavior of the correlations and the
A symmetry principle for topological quantum order
Nussinov, Zohar Ortiz, Gerardo
2009-05-15
We present a unifying framework to study physical systems which exhibit topological quantum order (TQO). The major guiding principle behind our approach is that of symmetries and entanglement. These symmetries may be actual symmetries of the Hamiltonian characterizing the system, or emergent symmetries. To this end, we introduce the concept of low-dimensional Gauge-like symmetries (GLSs), and the physical conservation laws (including topological terms, fractionalization, and the absence of quasi-particle excitations) which emerge from them. We prove then sufficient conditions for TQO at both zero and finite temperatures. The physical engine for TQO are topological defects associated with the restoration of GLSs. These defects propagate freely through the system and enforce TQO. Our results are strongest for gapped systems with continuous GLSs. At zero temperature, selection rules associated with the GLSs enable us to systematically construct general states with TQO; these selection rules do not rely on the existence of a finite gap between the ground states to all other excited states. Indices associated with these symmetries correspond to different topological sectors. All currently known examples of TQO display GLSs. Other systems exhibiting such symmetries include Hamiltonians depicting orbital-dependent spin-exchange and Jahn-Teller effects in transition metal orbital compounds, short-range frustrated Klein spin models, and p+ip superconducting arrays. The symmetry based framework discussed herein allows us to go beyond standard topological field theories and systematically engineer new physical models with finite temperature TQO (both Abelian and non-Abelian). Furthermore, we analyze the insufficiency of entanglement entropy (we introduce SU(N) Klein models on small world networks to make the argument even sharper), spectral structures, maximal string correlators, and fractionalization in establishing TQO. We show that Kitaev's Toric code model and Wen
Hierarchy of equations of multiple-time correlation functions
Alonso, Daniel; Vega, Ines de
2007-05-15
In this paper we derive the evolution equations for non-Markovian multiple-time correlation functions of an open quantum system without using any approximation. We find that these equations conform an open hierarchy in which N-time correlation functions are dependent on (N+1)-time correlations. This hierarchy of equations is consistently obtained with two different methods: A first one based on Heisenberg equations of system operators, and a second one based on system propagators. The dependency on higher order correlations, and therefore the open hierarchy structure, only disappears in certain particular cases and when some hypothesis or approximations are considered in the equations. In this paper we consider a perturbative approximation and derive the general evolution equation for N-time correlations. This equation turns to depend only on N-time and lower order correlation functions, conforming a closed hierarchy structure that is useful for computational purposes.
Digital Correlation Microwave Polarimetry: Analysis and Demonstration
NASA Technical Reports Server (NTRS)
Piepmeier, J. R.; Gasiewski, A. J.; Krebs, Carolyn A. (Technical Monitor)
2000-01-01
The design, analysis, and demonstration of a digital-correlation microwave polarimeter for use in earth remote sensing is presented. We begin with an analysis of three-level digital correlation and develop the correlator transfer function and radiometric sensitivity. A fifth-order polynomial regression is derived for inverting the digital correlation coefficient into the analog statistic. In addition, the effects of quantizer threshold asymmetry and hysteresis are discussed. A two-look unpolarized calibration scheme is developed for identifying correlation offsets. The developed theory and calibration method are verified using a 10.7 GHz and a 37.0 GHz polarimeter. The polarimeters are based upon 1-GS/s three-level digital correlators and measure the first three Stokes parameters. Through experiment, the radiometric sensitivity is shown to approach the theoretical as derived earlier in the paper and the two-look unpolarized calibration method is successfully compared with results using a polarimetric scheme. Finally, sample data from an aircraft experiment demonstrates that the polarimeter is highly-useful for ocean wind-vector measurement.
Phase correlation of foreign exchange time series
NASA Astrophysics Data System (ADS)
Wu, Ming-Chya
2007-03-01
Correlation of foreign exchange rates in currency markets is investigated based on the empirical data of USD/DEM and USD/JPY exchange rates for a period from February 1 1986 to December 31 1996. The return of exchange time series is first decomposed into a number of intrinsic mode functions (IMFs) by the empirical mode decomposition method. The instantaneous phases of the resultant IMFs calculated by the Hilbert transform are then used to characterize the behaviors of pricing transmissions, and the correlation is probed by measuring the phase differences between two IMFs in the same order. From the distribution of phase differences, our results show explicitly that the correlations are stronger in daily time scale than in longer time scales. The demonstration for the correlations in periods of 1986-1989 and 1990-1993 indicates two exchange rates in the former period were more correlated than in the latter period. The result is consistent with the observations from the cross-correlation calculation.
High-Fidelity Coding with Correlated Neurons
da Silveira, Rava Azeredo; Berry, Michael J.
2014-01-01
Positive correlations in the activity of neurons are widely observed in the brain. Previous studies have shown these correlations to be detrimental to the fidelity of population codes, or at best marginally favorable compared to independent codes. Here, we show that positive correlations can enhance coding performance by astronomical factors. Specifically, the probability of discrimination error can be suppressed by many orders of magnitude. Likewise, the number of stimuli encoded—the capacity—can be enhanced more than tenfold. These effects do not necessitate unrealistic correlation values, and can occur for populations with a few tens of neurons. We further show that both effects benefit from heterogeneity commonly seen in population activity. Error suppression and capacity enhancement rest upon a pattern of correlation. Tuning of one or several effective parameters can yield a limit of perfect coding: the corresponding pattern of positive correlation leads to a ‘lock-in’ of response probabilities that eliminates variability in the subspace relevant for stimulus discrimination. We discuss the nature of this pattern and we suggest experimental tests to identify it. PMID:25412463
Broadcasting of quantum correlations: Possibilities and impossibilities
NASA Astrophysics Data System (ADS)
Chatterjee, Sourav; Sazim, Sk; Chakrabarty, Indranil
2016-04-01
In this work, we extensively study the problem of broadcasting of quantum correlations (QCs). This includes broadcasting of quantum entanglement as well as correlations that go beyond the notion of entanglement (QCsbE). It is quite well known from the "no-broadcasting theorem" that perfect broadcasting of QCs is not possible. However, it does not rule out the possibility of partial broadcasting of QCs where we can get lesser correlated states from a given correlated state. In order to have a holistic view of broadcasting, we investigate this problem by starting with a most general representation of two qubit mixed states in terms of the Bloch vectors. As a cloning transformation we have used universal symmetric optimal Buzek-Hillery (BH) cloner both locally and nonlocally. Unlike entanglement, we find that it is impossible to broadcast QCsbE optimally. Lastly, we generalize these results for any symmetric or asymmetric cloning machines as well. This result brings out a fundamental difference between the correlations defined from the perspective of entanglement and the correlations measure which claims to go beyond entanglement.
Effects of Helicity on Lagrangian and Eulerian Time Correlations in Turbulence
NASA Technical Reports Server (NTRS)
Rubinstein, Robert; Zhou, Ye
1998-01-01
Taylor series expansions of turbulent time correlation functions are applied to show that helicity influences Eulerian time correlations more strongly than Lagrangian time correlations: to second order in time, the helicity effect on Lagrangian time correlations vanishes, but the helicity effect on Eulerian time correlations is nonzero. Fourier analysis shows that the helicity effect on Eulerian time correlations is confined to the largest inertial range scales. Some implications for sound radiation by swirling flows are discussed.
Exercise order in resistance training.
Simão, Roberto; de Salles, Belmiro Freitas; Figueiredo, Tiago; Dias, Ingrid; Willardson, Jeffrey M
2012-03-01
Resistance training (RT) is now an integral component of a well rounded exercise programme. For a correct training prescription, it is of the utmost importance to understand the interaction among training variables, such as the load, volume, rest interval between sets and exercises, frequency of sessions, exercise modality, repetition velocity and, finally, exercise order. Sports medicine research has indicated that exercise order is an important variable that affects both acute responses and chronic adaptations to RT programmes. Therefore, the purpose of this review was to analyse and discuss exercise order with relevance to acute responses (e.g. repetition performance) and also the expression of chronic adaptable characteristics (e.g. maximal strength and hypertrophy). To accomplish this purpose, the Scielo, Science Citation Index, National Library of Medicine, MEDLINE, Scopus, SPORTDiscus™ and CINAHL® databases were accessed to locate previously conducted original scientific investigations. The studies reviewed examined both acute responses and chronic adaptations with exercise order as the experimental variable. Generally, with relevance to acute responses, a key finding was that exercise order affects repetition performance over multiple sets, indicating that the total repetitions, and thus the volume, is greater when an exercise is placed at the beginning of an RT session, regardless of the relative amount of muscle mass involved. The pre-exhaustion method might not be an effective technique to increase the extent of neuromuscular recruitment for larger muscle groups (e.g. pectoralis major for the bench press) when preceded by a single-joint movement (e.g. pec-deck fly). With relevance to localized muscular endurance performance, oxygen consumption and ratings of perceived exertion, the limited amount of research conducted thus far indicates that exercise order does not appear to impact the acute expression of these variables. In terms of chronic
Multiscale high-order/low-order (HOLO) algorithms and applications
NASA Astrophysics Data System (ADS)
Chacón, L.; Chen, G.; Knoll, D. A.; Newman, C.; Park, H.; Taitano, W.; Willert, J. A.; Womeldorff, G.
2017-02-01
We review the state of the art in the formulation, implementation, and performance of so-called high-order/low-order (HOLO) algorithms for challenging multiscale problems. HOLO algorithms attempt to couple one or several high-complexity physical models (the high-order model, HO) with low-complexity ones (the low-order model, LO). The primary goal of HOLO algorithms is to achieve nonlinear convergence between HO and LO components while minimizing memory footprint and managing the computational complexity in a practical manner. Key to the HOLO approach is the use of the LO representations to address temporal stiffness, effectively accelerating the convergence of the HO/LO coupled system. The HOLO approach is broadly underpinned by the concept of nonlinear elimination, which enables segregation of the HO and LO components in ways that can effectively use heterogeneous architectures. The accuracy and efficiency benefits of HOLO algorithms are demonstrated with specific applications to radiation transport, gas dynamics, plasmas (both Eulerian and Lagrangian formulations), and ocean modeling. Across this broad application spectrum, HOLO algorithms achieve significant accuracy improvements at a fraction of the cost compared to conventional approaches. It follows that HOLO algorithms hold significant potential for high-fidelity system scale multiscale simulations leveraging exascale computing.
A Law of Order: Word Order Change in Classical Aztec
ERIC Educational Resources Information Center
Steele, Susan M.
1976-01-01
The verb in Classical Aztec is slowly moving from the end of the sentence to the beginning due to the attraction of sentence initial modal particles to the verb. Not only the function but also the position of elements should be examined to account for word-order change. (SCC)
Crystal nucleation as the ordering of multiple order parameters
NASA Astrophysics Data System (ADS)
Russo, John; Tanaka, Hajime
2016-12-01
Nucleation is an activated process in which the system has to overcome a free energy barrier in order for a first-order phase transition between the metastable and the stable phases to take place. In the liquid-to-solid transition, the process occurs between phases of different symmetry, and it is thus inherently a multi-dimensional process, in which all symmetries are broken at the transition. In this Focus Article, we consider some recent studies which highlight the multi-dimensional nature of the nucleation process. Even for a single-component system, the formation of solid crystals from the metastable melt involves fluctuations of two (or more) order parameters, often associated with the decoupling of positional and orientational symmetry breaking. In other words, we need at least two order parameters to describe the free-energy of a system including its liquid and crystalline states. This decoupling occurs naturally for asymmetric particles or directional interactions, focusing here on the case of water, but we will show that it also affects spherically symmetric interacting particles, such as the hard-sphere system. We will show how the treatment of nucleation as a multi-dimensional process has shed new light on the process of polymorph selection, on the effect of external fields on the nucleation process and on glass-forming ability.
Order in a multidimensional system.
Frieden, B Roy; Gatenby, Robert A
2011-07-01
We show that any convex K-dimensional system has a level of order R that is proportional to its level of Fisher information I. The proportionality constant is 1/8 the square of the longest chord connecting two surface points of the system. This result follows solely from the requirement that R decrease under small perturbations caused by a coarse graining of the system. The form for R is generally unitless, allowing the order for different phenomena, or different representations (e.g., using time vs frequency) of a given phenomenom, to be compared objectively. Order R is also invariant to uniform magnification of the system. The monotonic contraction properties of R and I define an arrow of time and imply that they are entropies, in addition to their usual status as informations. This also removes the need for data, and therefore an observer, in derivations of nonparticipatory phenomena that utilize I. Simple graphical examples of the new order measure show that it measures as well the level of "complexity" in the system. Finally, an application to cell growth during enforced distortion shows that a single hydrocarbon chain can be distorted into a membrane having equal order or complexity. Such membranes are prime constituents of living cells.
Detection of virus in shrimp using digital color correlation
NASA Astrophysics Data System (ADS)
Alvarez-Borrego, Josue; Chavez-Sanchez, Cristina; Bueno-Ibarra, Mario A.
1999-07-01
Detection of virus in shrimp tissue using digital color correlation is presented. Phase filters in three channels (red, green and blue) were used in order to detect HPV virus like target. These first results obtained showed that is possible to detect virus in shrimp tissue. More research must be made with color correlation in order to consider natural morphology of the virus, color, scale and rotation and noise in the samples.
Determining Reduced Order Models for Optimal Stochastic Reduced Order Models
Bonney, Matthew S.; Brake, Matthew R.W.
2015-08-01
The use of parameterized reduced order models(PROMs) within the stochastic reduced order model (SROM) framework is a logical progression for both methods. In this report, five different parameterized reduced order models are selected and critiqued against the other models along with truth model for the example of the Brake-Reuss beam. The models are: a Taylor series using finite difference, a proper orthogonal decomposition of the the output, a Craig-Bampton representation of the model, a method that uses Hyper-Dual numbers to determine the sensitivities, and a Meta-Model method that uses the Hyper-Dual results and constructs a polynomial curve to better represent the output data. The methods are compared against a parameter sweep and a distribution propagation where the first four statistical moments are used as a comparison. Each method produces very accurate results with the Craig-Bampton reduction having the least accurate results. The models are also compared based on time requirements for the evaluation of each model where the Meta- Model requires the least amount of time for computation by a significant amount. Each of the five models provided accurate results in a reasonable time frame. The determination of which model to use is dependent on the availability of the high-fidelity model and how many evaluations can be performed. Analysis of the output distribution is examined by using a large Monte-Carlo simulation along with a reduced simulation using Latin Hypercube and the stochastic reduced order model sampling technique. Both techniques produced accurate results. The stochastic reduced order modeling technique produced less error when compared to an exhaustive sampling for the majority of methods.
EDITORIAL: Strongly correlated electron systems Strongly correlated electron systems
NASA Astrophysics Data System (ADS)
Ronning, Filip; Batista, Cristian
2011-03-01
Strongly correlated electrons is an exciting and diverse field in condensed matter physics. This special issue aims to capture some of that excitement and recent developments in the field. Given that this issue was inspired by the 2010 International Conference on Strongly Correlated Electron Systems (SCES 2010), we briefly give some history in order to place this issue in context. The 2010 International Conference on Strongly Correlated Electron Systems was held in Santa Fe, New Mexico, a reunion of sorts from the 1989 International Conference on the Physics of Highly Correlated Electron Systems that also convened in Santa Fe. SCES 2010—co-chaired by John Sarrao and Joe Thompson—followed the tradition of earlier conferences, in this century, hosted by Buzios (2008), Houston (2007), Vienna (2005), Karlsruhe (2004), Krakow (2002) and Ann Arbor (2001). Every three years since 1997, SCES has joined the International Conference on Magnetism (ICM), held in Recife (2000), Rome (2003), Kyoto (2006) and Karlsruhe (2009). Like its predecessors, SCES 2010 topics included strongly correlated f- and d-electron systems, heavy-fermion behaviors, quantum-phase transitions, non-Fermi liquid phenomena, unconventional superconductivity, and emergent states that arise from electronic correlations. Recent developments from studies of quantum magnetism and cold atoms complemented the traditional subjects and were included in SCES 2010. 2010 celebrated the 400th anniversary of Santa Fe as well as the birth of astronomy. So what's the connection to SCES? The Dutch invention of the first practical telescope and its use by Galileo in 1610 and subsequent years overturned dogma that the sun revolved about the earth. This revolutionary, and at the time heretical, conclusion required innovative combinations of new instrumentation, observation and mathematics. These same combinations are just as important 400 years later and are the foundation of scientific discoveries that were discussed
Bootstrapped Deattenuated Correlation: Nonnormal Distributions
ERIC Educational Resources Information Center
Padilla, Miguel A.; Veprinsky, Anna
2014-01-01
Correlation attenuation due to measurement error and a corresponding correction, the deattenuated correlation, have been known for over a century. Nevertheless, the deattenuated correlation remains underutilized. A few studies in recent years have investigated factors affecting the deattenuated correlation, and a couple of them provide alternative…
Intermediate range order in alkaline borate glasses
NASA Astrophysics Data System (ADS)
Crupi, C.; Carini, G.; Ruello, G.; D'Angelo, G.
2016-03-01
We describe the neutron diffraction patterns of a series of alkaline borate glasses at different metal oxide content. Strong differences are observed in the intermediate range order as a function of the specific alkaline ion and of its concentration. On these results, we propose that the first sharp diffraction peak arises from correlations of atoms of voids and show that the compositional variation of this peak intensity in alkaline borate glasses is due to changes in the distribution of void sizes within the three-dimensional network. We argue that our interpretation in terms of interstitial (empty and/or filled) voids, having different sizes, provides a general explanation for all anomalous behaviours revealed for the first sharp diffraction peak.
Ordered pairing in liquid metallic hydrogen
NASA Technical Reports Server (NTRS)
Carlsson, A. E.; Ashcroft, N. W.
1983-01-01
We study two possible types of pairing involving the protons of a proposed low-temperature liquid phase metallic hydrogen. Electron-proton pairing, which can result in an insulating phase, is investigated by using an approximate solution of an Eliashberg-type equation for the anomalous self-energy. A very low estimate of the transition temperature is obtained by including proton correlations in the effective interaction. For proton-proton pairing, we derive a new proton pair potential based on the Abrikosov wave function. This potential includes the electron-proton interaction to all orders and has a much larger well depth than is obtained with linear screening methods. This suggests the possibility of either a superfluid paired phase analogous to that in He-3, or alternatively a phase with true molecular pairing.
Evolution of worldwide stock markets, correlation structure, and correlation-based graphs
NASA Astrophysics Data System (ADS)
Song, Dong-Ming; Tumminello, Michele; Zhou, Wei-Xing; Mantegna, Rosario N.
2011-08-01
We investigate the daily correlation present among market indices of stock exchanges located all over the world in the time period January 1996 to July 2009. We discover that the correlation among market indices presents both a fast and a slow dynamics. The slow dynamics reflects the development and consolidation of globalization. The fast dynamics is associated with critical events that originate in a specific country or region of the world and rapidly affect the global system. We provide evidence that the short term time scale of correlation among market indices is less than 3 trading months (about 60 trading days). The average values of the nondiagonal elements of the correlation matrix, correlation-based graphs, and the spectral properties of the largest eigenvalues and eigenvectors of the correlation matrix are carrying information about the fast and slow dynamics of the correlation of market indices. We introduce a measure of mutual information based on link co-occurrence in networks in order to detect the fast dynamics of successive changes of correlation-based graphs in a quantitative way.
Off-forward quark-quark correlation function
Casanova, Sabrina
2006-09-01
The properties of the nonforward quark-quark correlation function are examined. We derive constraints on the correlation function from the transformation properties of the fundamental fields of QCD occurring in its definition. We further develop a method to construct an Ansatz for this correlator. We present the complete leading order set of generalized parton distributions in terms of the amplitudes of the Ansatz. Finally we conclude that the number of independent generalized parton helicity changing distributions is four.
Genuine quantum and classical correlations in multipartite systems.
Giorgi, Gian Luca; Bellomo, Bruno; Galve, Fernando; Zambrini, Roberta
2011-11-04
Generalizing the quantifiers used to classify correlations in bipartite systems, we define genuine total, quantum, and classical correlations in multipartite systems. The measure we give is based on the use of relative entropy to quantify the distance between two density matrices. Moreover, we show that, for pure states of three qubits, both quantum and classical bipartite correlations obey a ladder ordering law fixed by two-body mutual informations, or, equivalently, by one-qubit entropies.
Correlation of light polarization in uncorrelated disordered magnetic media
NASA Astrophysics Data System (ADS)
Kozhaev, M. A.; Niyazov, R. A.; Belotelov, V. I.
2017-02-01
Light scattering in a magnetic medium with uncorrelated inclusions is theoretically studied in the approximation of the ladder diagram. Correlation between polarizations of electromagnetic waves that are produced by an infinitely distant dipole source is considered. Here a white-noise disorder model with Gaussian distribution is taken into account. In such a medium the magneto-optical interaction leads to correlation between perpendicular light polarizations. A spatial field correlation matrix with nonzero nondiagonal elements is obtained in the first order on gyration.
The Correlation between School Managers' Communication Skills and School Culture
ERIC Educational Resources Information Center
Sabanci, Ali; Sahin, Ahmet; Sönmez, Melek Alev; Yilmaz, Ozan
2016-01-01
The purpose of this study was to explore the correlation between school administrators' communication skills and school culture. This research was conducted as a survey using a descriptive method in order to ascertain the views of school managers and teachers about the correlation between school managers' communication skills and school culture in…
Correlates of Family Routines in Head Start Families
ERIC Educational Resources Information Center
Churchill, Susan L.; Stoneman, Zolinda
2004-01-01
The popular parenting literature places great importance on the role of routines in children's lives. Empirical research on family routines, however, is limited. This study examined correlates of family routines in a Head Start population in order to better understand their significance in the lives of families. Weak correlations were found…
Tree reconstruction from partial orders
Kannan, S.K. ); Warnow, T.J. )
1993-01-01
The problem of constructing trees given a matrix of interleaf distances is motivated by applications in computational evolutionary biology and linguistics. The general problem is to find an edge-weighted tree which most closely approximates the distance matrix. Although the construction problem is easy when the tree exactly fits the distance matrix, optimization problems under all popular criteria are either known or conjectured to be NP-complete. In this paper we consider the related problem where we are given a partial order on the pairwise distances, and wish to construct (if possible) an edge-weighted tree realizing the partial order. In particular we are interested in partial orders which arise from experiments on triples of species, which determine either a linear ordering of the three pairwise distances (called Total Order Model or TOM experiments) or only the pair(s) of minimum distance apart (called Partial Order Model or POM experiments). The POM and TOM experimental model is inspired by the model proposed by Kannan, Lawler, and Warnow for constructing trees from experiments which determine the rooted topology for any triple of species. We examine issues of construction of trees and consistency of TOM and POM experiments, where the trees may either be weighted or unweighted. Using these experiments to construct unweighted trees without nodes of degree two is motivated by a similar problem studied by Winkler, called the Discrete Metric Realization problem, which he showed to be strongly NP-hard. We have the following results: Determining consistency of a set of TOM or POM experiments is NP-Complete whether the tree is weighted or constrained to be unweighted and without degree two nodes. We can construct unweighted trees without degree two nodes from TOM experiments in optimal O(n[sup 3]) time and from POM experiments in O(n[sup 4]) time.
Tree reconstruction from partial orders
Kannan, S.K.; Warnow, T.J.
1993-03-01
The problem of constructing trees given a matrix of interleaf distances is motivated by applications in computational evolutionary biology and linguistics. The general problem is to find an edge-weighted tree which most closely approximates the distance matrix. Although the construction problem is easy when the tree exactly fits the distance matrix, optimization problems under all popular criteria are either known or conjectured to be NP-complete. In this paper we consider the related problem where we are given a partial order on the pairwise distances, and wish to construct (if possible) an edge-weighted tree realizing the partial order. In particular we are interested in partial orders which arise from experiments on triples of species, which determine either a linear ordering of the three pairwise distances (called Total Order Model or TOM experiments) or only the pair(s) of minimum distance apart (called Partial Order Model or POM experiments). The POM and TOM experimental model is inspired by the model proposed by Kannan, Lawler, and Warnow for constructing trees from experiments which determine the rooted topology for any triple of species. We examine issues of construction of trees and consistency of TOM and POM experiments, where the trees may either be weighted or unweighted. Using these experiments to construct unweighted trees without nodes of degree two is motivated by a similar problem studied by Winkler, called the Discrete Metric Realization problem, which he showed to be strongly NP-hard. We have the following results: Determining consistency of a set of TOM or POM experiments is NP-Complete whether the tree is weighted or constrained to be unweighted and without degree two nodes. We can construct unweighted trees without degree two nodes from TOM experiments in optimal O(n{sup 3}) time and from POM experiments in O(n{sup 4}) time.
Risk attitudes and birth order.
Krause, Philipp; Heindl, Johannes; Jung, Andreas; Langguth, Berthold; Hajak, Göran; Sand, Philipp G
2014-07-01
Risk attitudes play important roles in health behavior and everyday decision making. It is unclear, however, whether these attitudes can be predicted from birth order. We investigated 200 mostly male volunteers from two distinct settings. After correcting for multiple comparisons, for the number of siblings and for confounding by gender, ordinal position predicted perception of health-related risks among participants in extreme sports (p < .01). However, the direction of the effect contradicted Adlerian theory. Except for alcohol consumption, these findings extended to self-reported risk behavior. Together, the data call for a cautious stand on the impact of birth order on risk attitudes.
Ordering Multiple Soft Gluon Emissions
NASA Astrophysics Data System (ADS)
Ángeles Martínez, René; Forshaw, Jeffrey R.; Seymour, Michael H.
2016-05-01
We present an expression for the QCD amplitude for a general hard scattering process with any number of soft gluon emissions, to one-loop accuracy. The amplitude is written in two different but equivalent ways: as a product of operators ordered in dipole transverse momentum and as a product of loop-expanded currents. We hope that these results will help in the development of an all-orders algorithm for multiple emissions that includes the full color structure and both the real and imaginary contributions to the amplitude.
Strongly correlated Bose gases
NASA Astrophysics Data System (ADS)
Chevy, F.; Salomon, C.
2016-10-01
The strongly interacting Bose gas is one of the most fundamental paradigms of quantum many-body physics and the subject of many experimental and theoretical investigations. We review recent progress on strongly correlated Bose gases, starting with a description of beyond mean-field corrections. We show that the Efimov effect leads to non universal phenomena and to a metastability of the low temperature Bose gas through three-body recombination to deeply bound molecular states. We outline differences and similarities with ultracold Fermi gases, discuss recent experiments on the unitary Bose gas, and finally present a few perspectives for future research.
Universal optimal quantum correlator
NASA Astrophysics Data System (ADS)
Buscemi, Francesco; Dall'Arno, Michele; Ozawa, Masanao; Vedral, Vlatko
2014-10-01
Recently, a novel operational strategy to access quantum correlation functions of the form Tr[AρB] was provided in [F. Buscemi, M. Dall'Arno, M. Ozawa and V. Vedral, arXiv:1312.4240]. Here we propose a realization scheme, that we call partial expectation values, implementing such strategy in terms of a unitary interaction with an ancillary system followed by the measurement of an observable on the ancilla. Our scheme is universal, being independent of ρ, A, and B, and it is optimal in a statistical sense. Our scheme is suitable for implementation with present quantum optical technology, and provides a new way to test uncertainty relations.
Correlated multipartite quantum states
NASA Astrophysics Data System (ADS)
Batle, J.; Casas, M.; Plastino, A.
2013-03-01
We investigate quantum states that possess both maximum entanglement and maximum discord between the pertinent parties. Since entanglement (discord) is defined only for bipartite (two-qubit) systems, we use an appropriate sum over all bipartitions as the associated measure. The ensuing definition—not new for entanglement—is thus extended here to quantum discord. Also, additional dimensions within the parties are considered (qudits). We also discuss quantum correlations that induce Mermin's Bell-inequality violation for all multiqubit systems. One finds some differences when quantum mechanics is defined over the field of real or of complex numbers.
Digital Image Correlation Engine
Turner, Dan; Crozier, Paul; Reu, Phil
2015-10-06
DICe is an open source digital image correlation (DIC) tool intended for use as a module in an external application or as a standalone analysis code. It's primary capability is computing full field displacements and strains from sequences of digital These images are typically of a material sample undergoing a materials characterization experiment, but DICe is also useful for other applications (for example, trajectory tracking). DICe is machine portable (Windows, Linux and Mac) and can be effectively deployed on a high performance computing platform. Capabilities from DICe can be invoked through a library interface, via source code integration of DICe classes or through a graphical user interface.
Rotational Alignment Altered by Source Position Correlations
NASA Technical Reports Server (NTRS)
Jacobs, Chris S.; Heflin, M. B.; Lanyi, G. E.; Sovers, O. J.; Steppe, J. A.
2010-01-01
In the construction of modern Celestial Reference Frames (CRFs) the overall rotational alignment is only weakly constrained by the data. Therefore, common practice has been to apply a 3-dimensional No-Net-Rotation (NNR) constraint in order to align an under-construction frame to the ICRF. We present evidence that correlations amongst source position parameters must be accounted for in order to properly align a CRF at the 5-10 (mu)as level of uncertainty found in current work. Failure to do so creates errors at the 10-40 (mu)as level.
Correlation Structure of Fractional Pearson Diffusions.
Leonenko, Nikolai N; Meerschaert, Mark M; Sikorskii, Alla
2013-09-01
The stochastic solution to a diffusion equations with polynomial coefficients is called a Pearson diffusion. If the first time derivative is replaced by a Caputo fractional derivative of order less than one, the stochastic solution is called a fractional Pearson diffusion. This paper develops an explicit formula for the covariance function of a fractional Pearson diffusion in steady state, in terms of Mittag-Leffler functions. That formula shows that fractional Pearson diffusions are long range dependent, with a correlation that falls off like a power law, whose exponent equals the order of the fractional derivative.
Correlation Structure of Fractional Pearson Diffusions
Leonenko, Nikolai N.; Meerschaert, Mark M.; Sikorskii, Alla
2013-01-01
The stochastic solution to a diffusion equations with polynomial coefficients is called a Pearson diffusion. If the first time derivative is replaced by a Caputo fractional derivative of order less than one, the stochastic solution is called a fractional Pearson diffusion. This paper develops an explicit formula for the covariance function of a fractional Pearson diffusion in steady state, in terms of Mittag-Leffler functions. That formula shows that fractional Pearson diffusions are long range dependent, with a correlation that falls off like a power law, whose exponent equals the order of the fractional derivative. PMID:24089586
Modeling Ability Differentiation in the Second-Order Factor Model
ERIC Educational Resources Information Center
Molenaar, Dylan; Dolan, Conor V.; van der Maas, Han L. J.
2011-01-01
In this article we present factor models to test for ability differentiation. Ability differentiation predicts that the size of IQ subtest correlations decreases as a function of the general intelligence factor. In the Schmid-Leiman decomposition of the second-order factor model, we model differentiation by introducing heteroscedastic residuals,…
Birth order effects on autism symptom domains.
Reichenberg, Abraham; Smith, Christopher; Schmeidler, James; Silverman, Jeremy M
2007-03-30
Autism is predominantly genetically determined. Evidence supports familiality of the main sets of behavioral characteristics that define the syndrome of autism; however, possible non-genetic effects have also been suggested. The present study compared levels of autism symptom domains, as measured by the Autism Diagnostic Interview, and useful phrase speech scores between 106 pairs of first- and second-born siblings from multiply affected families. In addition, the intercorrelations between the measures were compared between siblings. The overall mean repetitive behavior total score was significantly higher (worse) in first-born than in second-born siblings. In contrast, first-born siblings had significantly lower (better) useful phrase speech than their younger siblings. Autism social and non-verbal communication scores were significantly correlated in first- and in second-born siblings. However, there was a significant difference in the coefficients between first- and second-born siblings. Performance on the non-verbal communication domain was also significantly and positively correlated with useful phrase speech score in both first- and second-born siblings. It is unclear at this time whether these results are of biologic origin. Nevertheless, the findings suggest that genetic studies in autism using specific levels of familial autism traits as phenotypes should take into account their intercorrelations and birth order effects embedded in the instrument.
Multiple soft limits of cosmological correlation functions
Joyce, Austin; Khoury, Justin; Simonović, Marko E-mail: jkhoury@sas.upenn.edu
2015-01-01
We derive novel identities satisfied by inflationary correlation functions in the limit where two external momenta are taken to be small. We derive these statements in two ways: using background-wave arguments and as Ward identities following from the fixed-time path integral. Interestingly, these identities allow us to constrain some of the O(q{sup 2}) components of the soft limit, in contrast to their single-soft analogues. We provide several nontrivial checks of our identities both in the context of resonant non-Gaussianities and in small sound speed models. Additionally, we extend the relation at lowest order in external momenta to arbitrarily many soft legs, and comment on the many-soft extension at higher orders in the soft momentum. Finally, we consider how higher soft limits lead to identities satisfied by correlation functions in large-scale structure.
Evolution of particle velocity correlations in sedimentation
NASA Astrophysics Data System (ADS)
Guazzelli, Elisabeth
2000-11-01
The problem of velocity fluctuations in sedimentation is still unresolved. The velocity fluctuations are observed experimentally to form into characteristic correlated regions [see Segre et al. (1997) and Bernard-Michel (2000)]. The origin of these correlations is still an open question. How correlation between particle velocities develops in a well mixed suspension? What is the ultimate structure of the sedimenting suspension? To tackle these questions, particle velocity fields are measured using particle image velocimetry. The sedimentation process is observed to be dominated by velocity fluctuation structures of the size of the container in the initial moments after the mixing, which diminish with time down to a size of the order of 20 interparticle spacings.
Electrostatic correlations near charged planar surfaces
Deng, Mingge; Em Karniadakis, George
2014-01-01
Electrostatic correlation effects near charged planar surfaces immersed in a symmetric electrolytes solution are systematically studied by numerically solving the nonlinear six-dimensional electrostatic self-consistent equations. We compare our numerical results with widely accepted mean-field (MF) theory results, and find that the MF theory remains quantitatively accurate only in weakly charged regimes, whereas in strongly charged regimes, the MF predictions deviate drastically due to the electrostatic correlation effects. We also observe a first-order like phase-transition corresponding to the counterion condensation phenomenon in strongly charged regimes, and compute the phase diagram numerically within a wide parameter range. Finally, we investigate the interactions between two likely-charged planar surfaces, which repulse each other as MF theory predicts in weakly charged regimes. However, our results show that they attract each other above a certain distance in strongly charged regimes due to significant electrostatic correlations. PMID:25194382
Multitime correlation functions in nonclassical stochastic processes
NASA Astrophysics Data System (ADS)
Krumm, F.; Sperling, J.; Vogel, W.
2016-06-01
A general method is introduced for verifying multitime quantum correlations through the characteristic function of the time-dependent P functional that generalizes the Glauber-Sudarshan P function. Quantum correlation criteria are derived which identify quantum effects for an arbitrary number of points in time. The Magnus expansion is used to visualize the impact of the required time ordering, which becomes crucial in situations when the interaction problem is explicitly time dependent. We show that the latter affects the multi-time-characteristic function and, therefore, the temporal evolution of the nonclassicality. As an example, we apply our technique to an optical parametric process with a frequency mismatch. The resulting two-time-characteristic function yields full insight into the two-time quantum correlation properties of such a system.
From correlation functions to event shapes
NASA Astrophysics Data System (ADS)
Belitsky, A. V.; Hohenegger, S.; Korchemsky, G. P.; Sokatchev, E.; Zhiboedov, A.
2014-07-01
functions; no summation over all final states is needed; no integration over the phase space is required. There is however a price to pay. In order to apply (1.2), we have to find an efficient way of computing the Euclidean correlation functions involving the product of source operators, O(0) and O†(x), and several charge operators O˜(xi), then analytically continue them to Minkowski signature to obtain the corresponding Wightman counterparts and, finally, integrate over the detector (or calorimeter) working time to get <0|O†(x)D[w]O(0)|0>. Conformal symmetry simplifies the form of the correlation functions enough to make this program of computing weighted cross sections from correlation functions an attractive enterprise.What is the utility of exploring charge flow correlations in CFTs? There are two immediate applications. The first one comes from the similarity of charge flow correlations in certain four-dimensional superconformal theories (e.g., N=4 SYM) at weak coupling with those in perturbative QCD. The hope is that by studying the former one can get some insight into the latter. Secondly, in the special case of energy correlations, σw(q) is expected to be a positive definite
CONDITIONAL DISTANCE CORRELATION
Wang, Xueqin; Pan, Wenliang; Hu, Wenhao; Tian, Yuan; Zhang, Heping
2015-01-01
Statistical inference on conditional dependence is essential in many fields including genetic association studies and graphical models. The classic measures focus on linear conditional correlations, and are incapable of characterizing non-linear conditional relationship including non-monotonic relationship. To overcome this limitation, we introduces a nonparametric measure of conditional dependence for multivariate random variables with arbitrary dimensions. Our measure possesses the necessary and intuitive properties as a correlation index. Briefly, it is zero almost surely if and only if two multivariate random variables are conditionally independent given a third random variable. More importantly, the sample version of this measure can be expressed elegantly as the root of a V or U-process with random kernels and has desirable theoretical properties. Based on the sample version, we propose a test for conditional independence, which is proven to be more powerful than some recently developed tests through our numerical simulations. The advantage of our test is even greater when the relationship between the multivariate random variables given the third random variable cannot be expressed in a linear or monotonic function of one random variable versus the other. We also show that the sample measure is consistent and weakly convergent, and the test statistic is asymptotically normal. By applying our test in a real data analysis, we are able to identify two conditionally associated gene expressions, which otherwise cannot be revealed. Thus, our measure of conditional dependence is not only an ideal concept, but also has important practical utility. PMID:26877569
Attosecond correlation dynamics
NASA Astrophysics Data System (ADS)
Ossiander, M.; Siegrist, F.; Shirvanyan, V.; Pazourek, R.; Sommer, A.; Latka, T.; Guggenmos, A.; Nagele, S.; Feist, J.; Burgdörfer, J.; Kienberger, R.; Schultze, M.
2016-11-01
Photoemission of an electron is commonly treated as a one-particle phenomenon. With attosecond streaking spectroscopy we observe the breakdown of this single active-electron approximation by recording up to six attoseconds retardation of the dislodged photoelectron due to electronic correlations. We recorded the photon-energy-dependent emission timing of electrons, released from the helium ground state by an extreme-ultraviolet photon, either leaving the ion in its ground state or exciting it into a shake-up state. We identify an optical field-driven d.c. Stark shift of charge-asymmetric ionic states formed after the entangled photoemission as a key contribution to the observed correlation time shift. These findings enable a complete wavepacket reconstruction and are universal for all polarized initial and final states. Sub-attosecond agreement with quantum mechanical ab initio modelling allows us to determine the absolute zero of time in the photoelectric effect to a precision better than 1/25th of the atomic unit of time.
Correlative Measurements Program
NASA Technical Reports Server (NTRS)
Parsons, C. L.
1988-01-01
The GSFC Correlative Measurements Program at the Wallops Flight Facility was represented on the Satellite/Satellite Intercomparisons Working Group. The Correlative Measurements Program uses the Rocket Ozonesonde (ROCOZ-A) and the Electrochemical Concentration Cell (ECC) balloon borne ozonesonde to measure the vertical profile of ozone amount in the atmosphere. The balloon work is described in a separate report. The ROCOZ-A instrument was used for many years to provide in situ truth data for various satellite ozone measuring systems, such as SBUV on Nimbus-7, SAGE-II, SBUV-II on the NOAA series of polar orbiting satellites, SME, LIMS, etc. The particular data sets of interest to the Ozone Trends Panel Working Group were collected at Natal, Brazil. The major results produced for and used by the Ozone Trends Panel are shown. The ROCOZ-A average ozone density profile is plotted versus altitude on the left. ECC ozonesondes were used for the portion of the profile below 20 km, the lower limit for ROCOZ-A. The difference between SAGE-II and ROCOZ-A average density profiles is shown.
Hexagonalization of correlation functions
NASA Astrophysics Data System (ADS)
Fleury, Thiago; Komatsu, Shota
2017-01-01
We propose a nonperturbative framework to study general correlation functions of single-trace operators in N = 4 supersymmetric Yang-Mills theory at large N . The basic strategy is to decompose them into fundamental building blocks called the hexagon form factors, which were introduced earlier to study structure constants using integrability. The decomposition is akin to a triangulation of a Riemann surface, and we thus call it hexagonalization. We propose a set of rules to glue the hexagons together based on symmetry, which naturally incorporate the dependence on the conformal and the R-symmetry cross ratios. Our method is conceptually different from the conventional operator product expansion and automatically takes into account multi-trace operators exchanged in OPE channels. To illustrate the idea in simple set-ups, we compute four-point functions of BPS operators of arbitrary lengths and correlation functions of one Konishi operator and three short BPS operators, all at one loop. In all cases, the results are in perfect agreement with the perturbative data. We also suggest that our method can be a useful tool to study conformal integrals, and show it explicitly for the case of ladder integrals.
Suffix Ordering and Morphological Processing
ERIC Educational Resources Information Center
Plag, Ingo; Baayen, Harald
2009-01-01
There is a long-standing debate about the principles constraining the combinatorial properties of suffixes. Hay 2002 and Hay & Plag 2004 proposed a model in which suffixes can be ordered along a hierarchy of processing complexity. We show that this model generalizes to a larger set of suffixes, and we provide independent evidence supporting the…
Spatial Processes in Linear Ordering
ERIC Educational Resources Information Center
von Hecker, Ulrich; Klauer, Karl Christoph; Wolf, Lukas; Fazilat-Pour, Masoud
2016-01-01
Memory performance in linear order reasoning tasks (A > B, B > C, C > D, etc.) shows quicker, and more accurate responses to queries on wider (AD) than narrower (AB) pairs on a hypothetical linear mental model (A -- B -- C -- D). While indicative of an analogue representation, research so far did not provide positive evidence for spatial…
Moral Order and the Humanities.
ERIC Educational Resources Information Center
Howard, Thomas
1980-01-01
Argues that a society without reverence for myths and history inevitably falls prone to chaos and evil, pointing to abortion, Andy Warhol's celebrity, and Woodstock as evidence of this disintegration of society. Proposes that humanities education expose students to human experience based on some awesome and fixed moral order. (AYC)
Questioning the Order of Operations
ERIC Educational Resources Information Center
Dupree, Kami M.
2016-01-01
For decades, students have been encouraged to use "Please Excuse My Dear Aunt Sally" as a means of learning the order of operations. Teachers unfamiliar with the Aunt Sally mnemonic are perhaps more familiar with a mnemonic such as PEMDAS. Each mnemonic is intended to convey "parentheses, exponents, multiplication, division,…
Order Statistics and Nonparametric Statistics.
2014-09-26
Topics investigated include the following: Probability that a fuze will fire; moving order statistics; distribution theory and properties of the...problem posed by an Army Scientist: A fuze will fire when at least n-i (or n-2) of n detonators function within time span t. What is the probability of
Geometric aspects of ordering phenomena
NASA Astrophysics Data System (ADS)
Cugliandolo, Leticia F.
2017-01-01
A macroscopic system prepared in a disordered phase and quenched across a second-order phase transition into an ordered phase undergoes a coarsening process whereby it orders locally in one of the equilibrium states. The study of the evolution of the morphology of the ordered structures in two dimensions has recently unveiled two interesting and generic features. On the one hand, the dynamics first approach a critical percolating state via the growth of a new lengthscale and satisfying scaling properties with respect to it. The time needed to reach the critical percolating state diverges with the system size, though more weakly than the equilibration time. On the other hand, once the critical percolating structures established, the geometrical and statistical properties at larger scales than the one established by the usual dynamic growing length remain the ones of critical percolation. These observations are common to different microscopic dynamics (single spin flip, local and non-local spin exchange, voter) in pure or weakly disordered systems. We discuss these results and we refer to the relevant publications for details. xml:lang="fr"
Nanoparticle Order through Entropic Confinement
NASA Astrophysics Data System (ADS)
Zhang, Ren; Lee, Bongjoon; Stafford, Christopher; Douglas, Jack; Bockstaller, Michael; Karim, Alamgir
As has been addressed in colloidal science, visual order transitions can be achieved with entropy contributions alone. Herein, entropy-driven ordering of nanoparticle (NP) structures is generated where entropy increase and visual order are achieved simultaneously. We study an ``athermal'' NP-polymer blends where NPs are densely grafted with polymer brush of the same chemical composition as the polymer matrix. Visual order of the NPs is induced by geometrically confining the thin film blends with meso-scale topographic patterns. When the residual layer thickness of the patterned blend films approaches the nanoparticle dimension, exclusive segregation of NPs to less confining imprinted mesa region occurs. This preferential segregation of NPs, defined by partition coefficient K = 0, is attributed to purely entropic penalty, where K denotes the particle density ratio at highly confined residual layer to that at mesa region. We further demonstrate K is fully tunable and even invertible with increasing matrix chain dimension. The associated entropic free energy change (ΔF = - ln K) is calculated to explain NP segregation preference. Accordingly, variation of residual layer thickness and polymer matrix molecule size can both affect NP distribution among patterned thick and thin regions.
Weighted order statistic classifiers with large rank-order margin.
Porter, R. B.; Hush, D. R.; Theiler, J. P.; Gokhale, M.
2003-01-01
We describe how Stack Filters and Weighted Order Statistic function classes can be used for classification problems. This leads to a new design criteria for linear classifiers when inputs are binary-valued and weights are positive . We present a rank-based measure of margin that can be directly optimized as a standard linear program and investigate its effect on generalization error with experiment. Our approach can robustly combine large numbers of base hypothesis and easily implement known priors through regularization.
NASA Astrophysics Data System (ADS)
Ivantsov, Ilya; Ferraz, Alvaro; Kochetov, Evgenii
2016-12-01
We perform quantum Monte Carlo simulations of the itinerant-localized periodic Kondo-Heisenberg model for the underdoped cuprates to calculate the associated spin correlation functions. The strong electron correlations are shown to play a key role in the abrupt destruction of the quasi-long-range antiferromagnetic order in the lightly doped regime.
Inelastic light scattering from correlated electrons
NASA Astrophysics Data System (ADS)
Devereaux, Thomas P.; Hackl, Rudi
2007-01-01
Inelastic light scattering is an intensively used tool in the study of electronic properties of solids. Triggered by the discovery of high-temperature superconductivity in the cuprates and by new developments in instrumentation, light scattering in both the visible (Raman effect) and x-ray part of the electromagnetic spectrum has become a method complementary to optical (infrared) spectroscopy while providing additional and relevant information. The main purpose of the review is to position Raman scattering with regard to single-particle methods like angle-resolved photoemission spectroscopy, and other transport and thermodynamic measurements in correlated materials. Particular focus will be placed on photon polarizations and the role of symmetry to elucidate the dynamics of electrons in different regions of the Brillouin zone. This advantage over conventional transport (usually measuring averaged properties) provides new insights into anisotropic and complex many-body behavior of electrons in various systems. Recent developments in the theory of electronic Raman scattering in correlated systems and experimental results in paradigmatic materials such as the A15 superconductors, magnetic and paramagnetic insulators, compounds with competing orders, as well as the cuprates with high superconducting transition temperatures are reviewed. An overview of the manifestations of complexity in the Raman response due to the impact of correlations and developing competing orders is presented. In a variety of materials, observations which may be understood and a summary of important open questions that pave the way to a detailed understanding of correlated electron systems, are discussed.
NASA Astrophysics Data System (ADS)
Madjid, F. Hadi; Myers, John M.
2016-10-01
The world runs on networks over which signals communicate sequences of symbols, e.g. numerals. Examining both engineered and natural communications networks reveals an unsuspected order that depends on contact with an unpredictable entity. This order has three roots. The first is a proof within quantum theory that no evidence can ever determine its explanation, so that an agent choosing an explanation must do so unpredictably. The second root is the showing that clocks that step computers do not "tell time" but serve as self-adjusting symbol-handling agents that regulate "logically synchronized" motion in response to unpredictable disturbances. Such a clock-agent has a certain independence as well as the capacity to communicate via unpredictable symbols with other clock-agents and to adjust its own tick rate in response to that communication. The third root is the noticing of unpredictable symbol exchange in natural systems, including the transmission of symbols found in molecular biology. We introduce a symbol-handling agent as a role played in some cases by a person, for example a physicist who chooses an explanation of given experimental outcomes, and in other cases by some other biological entity, and in still other cases by an inanimate device, such as a computer-based detector used in physical measurements. While we forbear to try to explain the propensity of agents at all levels from cells to civilizations to form and operate networks of logically synchronized symbol-handling agents, we point to this propensity as an overlooked cosmic order, an order structured by the unpredictability ensuing from the proof. Appreciating the cosmic order leads to a conception of agency that replaces volition by unpredictability and reconceives the notion of objectivity in a way that makes a place for agency in the world as described by physics. Some specific implications for physics are outlined.
Order-frequency analysis of machine signals
NASA Astrophysics Data System (ADS)
Abboud, D.; Antoni, J.
2017-03-01
Latest researches have asserted the eligibility of angle/time cyclostationarity in analyzing machine signals when operating under variable speed conditions. A core descriptor in this framework is the order-frequency spectral correlation (OFSC), basically estimated by the averaged cyclic periodogram (ACP), being able to jointly decode (i) the angle-dependent modulations related to the machine kinematics and (ii) the time-dependent carriers related to the machine dynamics. The present paper comes into this context with the aim of enriching this framework with new tools excerpted from cyclostationarity. In particular, a new estimator of the OFSC based on the cyclic modulation spectrum (CMS) is proposed and compared with the ACP in terms of resolution, statistical performance and computational cost. In addition, two related tools are theoretically addressed and their estimators are derived through the ACP and CMS. Specifically, the optimality of the ;order-frequency spectral coherence; (the normalized/whitened form of the OFSC) in revealing cyclic components according to their SNR is demonstrated. Also, the ;improved envelope spectrum; is derived from the latter by integrating over the spectral frequency variable, evidencing considerable enhancement over the squared envelope spectrum. The potentiality of the proposed tools and the adequacy of the related estimators are experimentally investigated on simulated and real-world vibration signals.