Nuclear correlations and structure functions

International Nuclear Information System (INIS)

Hu Guoju; Irvine, J.M.

1989-01-01

It is argued that the search for a mass number dependence of the nuclear structure function per nucleon is profitably directed to the region of Bjorken scaling variable x > 1. We show that in the convolution model of the nuclear structure function the nuclear momentum distribution and energy spectrum generated by cluster expansion techniques, here realised in the correlated basis function method, invoking tensor correlations and short-range density-dependent repulsions adequately describes the structure function for 12 C in the region x > 1. The results of structure functions for a number of light-, medium- and heavy-mass nuclei are presented. (author)

Significance and properties of internucleon correlation functions

OpenAIRE

Suzuki, Y.; Horiuchi, W.

2008-01-01

We show that a nuclear Hamiltonian and a set of internucleon correlation functions is in a one-to-one correspondence. The correlation functions for $s$-shell nuclei interacting via the two-nucleon interaction of AV8$^\\prime$ type are calculated to exhibit the importance of tensor correlations as well as short-range central correlation. The asymptotic behavior of the correlation functions is also discussed.

Structuring Stokes correlation functions using vector-vortex beam

Science.gov (United States)

Kumar, Vijay; Anwar, Ali; Singh, R. P.

2018-01-01

Higher order statistical correlations of the optical vector speckle field, formed due to scattering of a vector-vortex beam, are explored. Here, we report on the experimental construction of the Stokes parameters covariance matrix, consisting of all possible spatial Stokes parameters correlation functions. We also propose and experimentally realize a new Stokes correlation functions called Stokes field auto correlation functions. It is observed that the Stokes correlation functions of the vector-vortex beam will be reflected in the respective Stokes correlation functions of the corresponding vector speckle field. The major advantage of proposing Stokes correlation functions is that the Stokes correlation function can be easily tuned by manipulating the polarization of vector-vortex beam used to generate vector speckle field and to get the phase information directly from the intensity measurements. Moreover, this approach leads to a complete experimental Stokes characterization of a broad range of random fields.

Two-proton correlation function: a gentle introduction

International Nuclear Information System (INIS)

Deloff, A.

2007-01-01

The recent COSY-11 collaboration measurement of the two-proton correlation function in the pp→ppη reaction, reported at this meeting [1], arouse some interest in a simple theoretical description of the correlation function. In these notes we present a pedagogical introduction to the practical methods that can be used for calculating the correlation function

Correlation functions of Coulomb branch operators

Energy Technology Data Exchange (ETDEWEB)

Gerchkovitz, Efrat [Weizmann Institute of Science,Rehovot 76100 (Israel); Gomis, Jaume [Perimeter Institute for Theoretical Physics,Waterloo, ON N2L 2Y5 (Canada); Ishtiaque, Nafiz [Perimeter Institute for Theoretical Physics,Waterloo, ON N2L 2Y5 (Canada); Department of Physics, University of Waterloo,Waterloo, ON N2L 3G1 (Canada); Karasik, Avner; Komargodski, Zohar [Weizmann Institute of Science,Rehovot 76100 (Israel); Pufu, Silviu S. [Joseph Henry Laboratories, Princeton University,Princeton, NJ 08544 (United States)

2017-01-24

We consider the correlation functions of Coulomb branch operators in four-dimensional N=2 Superconformal Field Theories (SCFTs) involving exactly one anti-chiral operator. These extremal correlators are the “minimal' non-holomorphic local observables in the theory. We show that they can be expressed in terms of certain determinants of derivatives of the four-sphere partition function of an appropriate deformation of the SCFT. This relation between the extremal correlators and the deformed four-sphere partition function is non-trivial due to the presence of conformal anomalies, which lead to operator mixing on the sphere. Evaluating the deformed four-sphere partition function using supersymmetric localization, we compute the extremal correlators explicitly in many interesting examples. Additionally, the representation of the extremal correlators mentioned above leads to a system of integrable differential equations. We compare our exact results with previous perturbative computations and with the four-dimensional tt{sup ∗} equations. We also use our results to study some of the asymptotic properties of the perturbative series expansions we obtain in N=2 SQCD.

Pheochromocytoma with Markedly Abnormal Liver Function Tests and Severe Leukocytosis

Directory of Open Access Journals (Sweden)

Chai Ryoung Eun

2014-03-01

Full Text Available Pheochromocytoma is a rare neuroendocrine tumor arising from the medulla of the adrenal glands, which causes an overproduction of catecholamines. The common symptoms are headache, palpitations, and sweating; however, various other clinical manifestations might also be present. Accurate diagnosis of pheochromocytoma is important because surgical treatment is usually successful, and associated clinical problems are reversible if treated early. A 49-year-old man with a history of uncontrolled hypertension and diabetes mellitus presented with chest pain, fever, and sweating. His liver function tests and white blood cell counts were markedly increased and his echocardiography results suggested stress-induced cardiomyopathy. His abdominal computed tomography showed a 5×5-cm-sized tumor in the left adrenal gland, and laboratory tests confirmed catecholamine overproduction. After surgical resection of the left adrenal gland, his liver function tests and white blood cell counts normalized, and echocardiography showed normal cardiac function. Moreover, his previous antihypertensive regimen was deescalated, and his previously uncontrolled blood glucose levels normalized without medication.

fCCAC: functional canonical correlation analysis to evaluate covariance between nucleic acid sequencing datasets.

Science.gov (United States)

Madrigal, Pedro

2017-03-01

Computational evaluation of variability across DNA or RNA sequencing datasets is a crucial step in genomic science, as it allows both to evaluate reproducibility of biological or technical replicates, and to compare different datasets to identify their potential correlations. Here we present fCCAC, an application of functional canonical correlation analysis to assess covariance of nucleic acid sequencing datasets such as chromatin immunoprecipitation followed by deep sequencing (ChIP-seq). We show how this method differs from other measures of correlation, and exemplify how it can reveal shared covariance between histone modifications and DNA binding proteins, such as the relationship between the H3K4me3 chromatin mark and its epigenetic writers and readers. An R/Bioconductor package is available at http://bioconductor.org/packages/fCCAC/ . pmb59@cam.ac.uk. Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

A pair density functional theory utilizing the correlated wave function

International Nuclear Information System (INIS)

Higuchi, M; Higuchi, K

2009-01-01

We propose a practical scheme for calculating the ground-state pair density (PD) by utilizing the correlated wave function. As the correlated wave function, we adopt a linear combination of the single Slater determinants that are constructed from the solutions of the initial scheme [Higuchi M and Higuchi K 2007 Physica B 387, 117]. The single-particle equation is derived by performing the variational principle within the set of PDs that are constructed from such correlated wave functions. Since the search region of the PD is substantially extended as compared with the initial scheme, it is expected that the present scheme can cover more correlation effects. The single-particle equation is practical, and may be easily applied to actual calculations.

Integral equations of hadronic correlation functions a functional- bootstrap approach

CERN Document Server

Manesis, E K

1974-01-01

A reasonable 'microscopic' foundation of the Feynman hadron-liquid analogy is offered, based on a class of models for hadron production. In an external field formalism, the equivalence (complementarity) of the exclusive and inclusive descriptions of hadronic reactions is specifically expressed in a functional-bootstrap form, and integral equations between inclusive and exclusive correlation functions are derived. Using the latest CERN-ISR data on the two-pion inclusive correlation function, and assuming rapidity translational invariance for the exclusive one, the simplest integral equation is solved in the 'central region' and an exclusive correlation length in rapidity predicted. An explanation is also offered for the unexpected similarity observed between pi /sup +/ pi /sup -/ and pi /sup -/ pi /sup -/ inclusive correlations. (31 refs).

Correlation functions in first-order phase transitions

Science.gov (United States)

Garrido, V.; Crespo, D.

1997-09-01

Most of the physical properties of systems underlying first-order phase transitions can be obtained from the spatial correlation functions. In this paper, we obtain expressions that allow us to calculate all the correlation functions from the droplet size distribution. Nucleation and growth kinetics is considered, and exact solutions are obtained for the case of isotropic growth by using self-similarity properties. The calculation is performed by using the particle size distribution obtained by a recently developed model (populational Kolmogorov-Johnson-Mehl-Avrami model). Since this model is less restrictive than that used in previously existing theories, the result is that the correlation functions can be obtained for any dependence of the kinetic parameters. The validity of the method is tested by comparison with the exact correlation functions, which had been obtained in the available cases by the time-cone method. Finally, the correlation functions corresponding to the microstructure developed in partitioning transformations are obtained.

Relations between correlation functions in gauge field theory

International Nuclear Information System (INIS)

Simonov, Yu. A.; Shevchenko, V. I.

1997-01-01

Exact relations between vacuum correlations of non-Abelian field strengths are obtained. With the aid of exterior differentiation, the invariant parts of a given correlation function are expressed in terms of higher order correlation functions. The corollaries of these relations for the behavior of nonperturbative correlation functions at small and large distances are deduced

A cumulant functional for static and dynamic correlation

International Nuclear Information System (INIS)

Hollett, Joshua W.; Hosseini, Hessam; Menzies, Cameron

2016-01-01

A functional for the cumulant energy is introduced. The functional is composed of a pair-correction and static and dynamic correlation energy components. The pair-correction and static correlation energies are functionals of the natural orbitals and the occupancy transferred between near-degenerate orbital pairs, rather than the orbital occupancies themselves. The dynamic correlation energy is a functional of the statically correlated on-top two-electron density. The on-top density functional used in this study is the well-known Colle-Salvetti functional. Using the cc-pVTZ basis set, the functional effectively models the bond dissociation of H 2 , LiH, and N 2 with equilibrium bond lengths and dissociation energies comparable to those provided by multireference second-order perturbation theory. The performance of the cumulant functional is less impressive for HF and F 2 , mainly due to an underestimation of the dynamic correlation energy by the Colle-Salvetti functional.

Non-perturbative QCD correlation functions

Energy Technology Data Exchange (ETDEWEB)

Cyrol, Anton Konrad

2017-11-27

Functional methods provide access to the non-perturbative regime of quantum chromo- dynamics. Hence, they allow investigating confinement and chiral symmetry breaking. In this dissertation, correlation functions of Yang-Mills theory and unquenched two-flavor QCD are computed from the functional renormalization group. Employing a self-consistent vertex expansion of the effective action, Yang-Mills correlation functions are obtained in four as well as in three spacetime dimensions. To this end, confinement and Slavnov-Taylor identities are discussed. Our numerical results show very good agreement with corresponding lattice results. Next, unquenched two-flavor QCD is considered where it is shown that the unquenched two-flavor gluon propagator is insensitive to the pion mass. Furthermore, the necessity for consistent truncations is emphasized. Finally, correlation functions of finite-temperature Yang-Mills theory are computed in a truncation that includes the splitting of the gluon field into directions that are transverse and longitudinal to the heat bath. In particular, it includes the splitting of the three- and four-gluon vertices. The obtained gluon propagator allows to extract a Debye screening mass that coincides with the hard thermal loop screening mass at high temperatures, but is meaningful also at temperatures below the phase transition temperature.

Correlation Functions in Open Quantum-Classical Systems

Directory of Open Access Journals (Sweden)

Chang-Yu Hsieh

2013-12-01

Full Text Available Quantum time correlation functions are often the principal objects of interest in experimental investigations of the dynamics of quantum systems. For instance, transport properties, such as diffusion and reaction rate coefficients, can be obtained by integrating these functions. The evaluation of such correlation functions entails sampling from quantum equilibrium density operators and quantum time evolution of operators. For condensed phase and complex systems, where quantum dynamics is difficult to carry out, approximations must often be made to compute these functions. We present a general scheme for the computation of correlation functions, which preserves the full quantum equilibrium structure of the system and approximates the time evolution with quantum-classical Liouville dynamics. Several aspects of the scheme are discussed, including a practical and general approach to sample the quantum equilibrium density, the properties of the quantum-classical Liouville equation in the context of correlation function computations, simulation schemes for the approximate dynamics and their interpretation and connections to other approximate quantum dynamical methods.

Correlation functions of two-matrix models

International Nuclear Information System (INIS)

Bonora, L.; Xiong, C.S.

1993-11-01

We show how to calculate correlation functions of two matrix models without any approximation technique (except for genus expansion). In particular we do not use any continuum limit technique. This allows us to find many solutions which are invisible to the latter technique. To reach our goal we make full use of the integrable hierarchies and their reductions which were shown in previous papers to naturally appear in multi-matrix models. The second ingredient we use, even though to a lesser extent, are the W-constraints. In fact an explicit solution of the relevant hierarchy, satisfying the W-constraints (string equation), underlies the explicit calculation of the correlation functions. The correlation functions we compute lend themselves to a possible interpretation in terms of topological field theories. (orig.)

Correlation function of the luminosity distances

Energy Technology Data Exchange (ETDEWEB)

Biern, Sang Gyu; Yoo, Jaiyul, E-mail: sgbiern@physik.uzh.ch, E-mail: jyoo@physik.uzh.ch [Center for Theoretical Astrophysics and Cosmology, Institute for Computational Science, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich (Switzerland)

2017-09-01

We present the correlation function of the luminosity distances in a flat ΛCDM universe. Decomposing the luminosity distance fluctuation into the velocity, the gravitational potential, and the lensing contributions in linear perturbation theory, we study their individual contributions to the correlation function. The lensing contribution is important at large redshift ( z ∼> 0.5) but only for small angular separation (θ ∼< 3°), while the velocity contribution dominates over the other contributions at low redshift or at larger separation. However, the gravitational potential contribution is always subdominant at all scale, if the correct gauge-invariant expression is used. The correlation function of the luminosity distances depends significantly on the matter content, especially for the lensing contribution, thus providing a novel tool of estimating cosmological parameters.

Correlation functional in screened-exchange density functional theory procedures.

Science.gov (United States)

Chan, Bun; Kawashima, Yukio; Hirao, Kimihiko

2017-10-15

In the present study, we have explored several prospects for the further development of screened-exchange density functional theory (SX-DFT) procedures. Using the performance of HSE06 as our measure, we find that the use of alternative correlation functionals (as oppose to PBEc in HSE06) also yields adequate results for a diverse set of thermochemical properties. We have further examined the performance of new SX-DFT procedures (termed HSEB-type methods) that comprise the HSEx exchange and a (near-optimal) reparametrized B97c (c OS,0  = c SS,0  = 1, c OS,1  = -1.5, c OS,2  = -0.644, c SS,1  = -0.5, and c SS,2  = 1.10) correlation functionals. The different variants of HSEB all perform comparably to or slightly better than the original HSE-type procedures. These results, together with our fundamental analysis of correlation functionals, point toward various directions for advancing SX-DFT methods. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Nucleon-nucleon momentum correlation function for light nuclei

International Nuclear Information System (INIS)

Ma, Y.G.; Cai, X.Z.; Chen, J.G.; Fang, D.Q.; Guo, W.; Liu, G.H.; Ma, C.W.; Ma, E.J.; Shen, W.Q.; Shi, Y.; Su, Q.M.; Tian, W.D.; Wang, H.W.; Wang, K.; Wei, Y.B.; Yan, T.Z.

2007-01-01

Nucleon-nucleon momentum correlation function have been presented for nuclear reactions with neutron-rich or proton-rich projectiles using a nuclear transport theory, namely Isospin-Dependent Quantum Molecular Dynamics model. The relationship between the binding energy of projectiles and the strength of proton-neutron correlation function at small relative momentum has been explored, while proton-proton correlation function shows its sensitivity to the proton density distribution. Those results show that nucleon-nucleon correlation function is useful to reflect some features of the neutron- or proton-halo nuclei and therefore provide a potential tool for the studies of radioactive beam physics

The correlation function for density perturbations in an expanding universe. IV - The evolution of the correlation function. [galaxy distribution

Science.gov (United States)

Mcclelland, J.; Silk, J.

1979-01-01

The evolution of the two-point correlation function for the large-scale distribution of galaxies in an expanding universe is studied on the assumption that the perturbation densities lie in a Gaussian distribution centered on any given mass scale. The perturbations are evolved according to the Friedmann equation, and the correlation function for the resulting distribution of perturbations at the present epoch is calculated. It is found that: (1) the computed correlation function gives a satisfactory fit to the observed function in cosmological models with a density parameter (Omega) of approximately unity, provided that a certain free parameter is suitably adjusted; (2) the power-law slope in the nonlinear regime reflects the initial fluctuation spectrum, provided that the density profile of individual perturbations declines more rapidly than the -2.4 power of distance; and (3) both positive and negative contributions to the correlation function are predicted for cosmological models with Omega less than unity.

Generalized hydrodynamic correlations and fractional memory functions

Science.gov (United States)

Rodríguez, Rosalio F.; Fujioka, Jorge

2015-12-01

A fractional generalized hydrodynamic (GH) model of the longitudinal velocity fluctuations correlation, and its associated memory function, for a complex fluid is analyzed. The adiabatic elimination of fast variables introduces memory effects in the transport equations, and the dynamic of the fluctuations is described by a generalized Langevin equation with long-range noise correlations. These features motivate the introduction of Caputo time fractional derivatives and allows us to calculate analytic expressions for the fractional longitudinal velocity correlation function and its associated memory function. Our analysis eliminates a spurious constant term in the non-fractional memory function found in the non-fractional description. It also produces a significantly slower power-law decay of the memory function in the GH regime that reduces to the well-known exponential decay in the non-fractional Navier-Stokes limit.

IMPROVING CORRELATION FUNCTION FITTING WITH RIDGE REGRESSION: APPLICATION TO CROSS-CORRELATION RECONSTRUCTION

International Nuclear Information System (INIS)

Matthews, Daniel J.; Newman, Jeffrey A.

2012-01-01

Cross-correlation techniques provide a promising avenue for calibrating photometric redshifts and determining redshift distributions using spectroscopy which is systematically incomplete (e.g., current deep spectroscopic surveys fail to obtain secure redshifts for 30%-50% or more of the galaxies targeted). In this paper, we improve on the redshift distribution reconstruction methods from our previous work by incorporating full covariance information into our correlation function fits. Correlation function measurements are strongly covariant between angular or spatial bins, and accounting for this in fitting can yield substantial reduction in errors. However, frequently the covariance matrices used in these calculations are determined from a relatively small set (dozens rather than hundreds) of subsamples or mock catalogs, resulting in noisy covariance matrices whose inversion is ill-conditioned and numerically unstable. We present here a method of conditioning the covariance matrix known as ridge regression which results in a more well behaved inversion than other techniques common in large-scale structure studies. We demonstrate that ridge regression significantly improves the determination of correlation function parameters. We then apply these improved techniques to the problem of reconstructing redshift distributions. By incorporating full covariance information, applying ridge regression, and changing the weighting of fields in obtaining average correlation functions, we obtain reductions in the mean redshift distribution reconstruction error of as much as ∼40% compared to previous methods. We provide a description of POWERFIT, an IDL code for performing power-law fits to correlation functions with ridge regression conditioning that we are making publicly available.

Leukocyte subtype counts and its association with vascular structure and function in adults with intermediate cardiovascular risk. MARK study.

Directory of Open Access Journals (Sweden)

Leticia Gomez-Sanchez

Full Text Available We investigated the relationship between leukocyte subtype counts and vascular structure and function based on carotid intima-media thickness, pulse wave velocity, central augmentation index and cardio-ankle vascular index by gender in intermediate cardiovascular risk patients.This study analyzed 500 subjects who were included in the MARK study, aged 35 to 74 years (mean: 60.3±8.4, 45.6% women.Brachial ankle Pulse Wave Velocity (ba-PWV estimate by equation, Cardio-AnkleVascular Index (CAVI using the VaSera device and Carotid ultrasound was used to measure carotid Intima Media Thickness (IMT. The Mobil-O-Graph was used to measure the Central Augmentation Index (CAIx.Total leukocyte, neutrophil and monocyte counts were positively correlated with IMT (p < 0.01 in men. Monocyte count was positively correlated with CAIx in women (p < 0.01. In a multiple linear regression analysis, the IMT mean maintained a positive association with the neutrophil count (β = 1.500, p = 0.007 in men. CAIx maintained a positive association with the monocyte count (β = 2.445, p = 0.022 in women.The results of this study suggest that the relationship between subtype circulating leukocyte counts and vascular structure and function, although small, may be different by gender. In men, the neutrophil count was positively correlated with IMT and in women, the monocyte count with CAIx, in a large sample of intermediate-risk patients. These association were maintained after adjusting for age and other confounders.ClinicalTrials.gov NCT01428934.

Correlation Functions in Open Quantum-Classical Systems

OpenAIRE

Hsieh, Chang-Yu; Kapral, Raymond

2013-01-01

Quantum time correlation functions are often the principal objects of interest in experimental investigations of the dynamics of quantum systems. For instance, transport properties, such as diffusion and reaction rate coefficients, can be obtained by integrating these functions. The evaluation of such correlation functions entails sampling from quantum equilibrium density operators and quantum time evolution of operators. For condensed phase and complex systems, where quantum dynamics is diff...

42 CFR 476.86 - Correlation of Title XI functions with Title XVIII functions.

Science.gov (United States)

2010-10-01

... 42 Public Health 4 2010-10-01 2010-10-01 false Correlation of Title XI functions with Title XVIII functions. 476.86 Section 476.86 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF...) Qio Review Functions § 476.86 Correlation of Title XI functions with Title XVIII functions. (a...

Hexagonalization of correlation functions

Energy Technology Data Exchange (ETDEWEB)

Fleury, Thiago [Instituto de Física Teórica, UNESP - University Estadual Paulista,ICTP South American Institute for Fundamental Research,Rua Dr. Bento Teobaldo Ferraz 271, 01140-070, São Paulo, SP (Brazil); Komatsu, Shota [Perimeter Institute for Theoretical Physics,31 Caroline St N Waterloo, Ontario N2L 2Y5 (Canada)

2017-01-30

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.

Algebraic relaxation of a time correlation function

International Nuclear Information System (INIS)

Srivastava, S.; Kumar, C.N.; Tankeshwar, K.

2004-06-01

A second order non-linear differential equation obtained from Mori's integro- differential equation is shown to transform to another form which provides algebraic decay to a time correlation function. Involved parameters in algebraic formula are related to exact properties of the corresponding correlation function. The model has been used to study a sol-gel system which is known, experimentally, to exhibit a power law decay to stress auto-correlation function. The expression obtained for the viscosity shows a logarithmic divergence at some critical value of the parameter. Some features of the model have also been tested using available information about Lennard-Jones fluids. (author)

Automatic Extraction of Road Markings from Mobile Laser Scanning Data

Science.gov (United States)

Ma, H.; Pei, Z.; Wei, Z.; Zhong, R.

2017-09-01

Road markings as critical feature in high-defination maps, which are Advanced Driver Assistance System (ADAS) and self-driving technology required, have important functions in providing guidance and information to moving cars. Mobile laser scanning (MLS) system is an effective way to obtain the 3D information of the road surface, including road markings, at highway speeds and at less than traditional survey costs. This paper presents a novel method to automatically extract road markings from MLS point clouds. Ground points are first filtered from raw input point clouds using neighborhood elevation consistency method. The basic assumption of the method is that the road surface is smooth. Points with small elevation-difference between neighborhood are considered to be ground points. Then ground points are partitioned into a set of profiles according to trajectory data. The intensity histogram of points in each profile is generated to find intensity jumps in certain threshold which inversely to laser distance. The separated points are used as seed points to region grow based on intensity so as to obtain road mark of integrity. We use the point cloud template-matching method to refine the road marking candidates via removing the noise clusters with low correlation coefficient. During experiment with a MLS point set of about 2 kilometres in a city center, our method provides a promising solution to the road markings extraction from MLS data.

Surface laser marking optimization using an experimental design approach

Science.gov (United States)

Brihmat-Hamadi, F.; Amara, E. H.; Lavisse, L.; Jouvard, J. M.; Cicala, E.; Kellou, H.

2017-04-01

Laser surface marking is performed on a titanium substrate using a pulsed frequency doubled Nd:YAG laser ( λ= 532 nm, τ pulse=5 ns) to process the substrate surface under normal atmospheric conditions. The aim of the work is to investigate, following experimental and statistical approaches, the correlation between the process parameters and the response variables (output), using a Design of Experiment method (DOE): Taguchi methodology and a response surface methodology (RSM). A design is first created using MINTAB program, and then the laser marking process is performed according to the planned design. The response variables; surface roughness and surface reflectance were measured for each sample, and incorporated into the design matrix. The results are then analyzed and the RSM model is developed and verified for predicting the process output for the given set of process parameters values. The analysis shows that the laser beam scanning speed is the most influential operating factor followed by the laser pumping intensity during marking, while the other factors show complex influences on the objective functions.

Memory functions and correlations in additive binary Markov chains

Energy Technology Data Exchange (ETDEWEB)

Melnyk, S S [A Ya Usikov Institute for Radiophysics and Electronics, Ukrainian Academy of Science, 12 Proskura Street, 61085 Kharkov (Ukraine); Usatenko, O V [A Ya Usikov Institute for Radiophysics and Electronics, Ukrainian Academy of Science, 12 Proskura Street, 61085 Kharkov (Ukraine); Yampol' skii, V A [A Ya Usikov Institute for Radiophysics and Electronics, Ukrainian Academy of Science, 12 Proskura Street, 61085 Kharkov (Ukraine); Apostolov, S S [V N Karazin Kharkov National University, 4 Svoboda Sq., Kharkov 61077 (Ukraine); Maiselis, Z A [V N Karazin Kharkov National University, 4 Svoboda Sq., Kharkov 61077 (Ukraine)

2006-11-17

A theory of additive Markov chains with a long-range memory, proposed earlier in Usatenko et al (2003 Phys. Rev. E 68 061107), is developed and used to describe statistical properties of long-range correlated systems. The convenient characteristics of such systems, memory functions and their relation to the correlation properties of the systems are examined. Various methods for finding the memory function via the correlation function are proposed. The inverse problem (calculation of the correlation function by means of the prescribed memory function) is also solved. This is demonstrated for the analytically solvable model of the system with a step-wise memory function.

Memory functions and correlations in additive binary Markov chains

International Nuclear Information System (INIS)

Melnyk, S S; Usatenko, O V; Yampol'skii, V A; Apostolov, S S; Maiselis, Z A

2006-01-01

A theory of additive Markov chains with a long-range memory, proposed earlier in Usatenko et al (2003 Phys. Rev. E 68 061107), is developed and used to describe statistical properties of long-range correlated systems. The convenient characteristics of such systems, memory functions and their relation to the correlation properties of the systems are examined. Various methods for finding the memory function via the correlation function are proposed. The inverse problem (calculation of the correlation function by means of the prescribed memory function) is also solved. This is demonstrated for the analytically solvable model of the system with a step-wise memory function

Structural and functional cerebral correlates of hypnotic suggestibility.

Directory of Open Access Journals (Sweden)

Alexa Huber

Full Text Available Little is known about the neural bases of hypnotic suggestibility, a cognitive trait referring to the tendency to respond to hypnotic suggestions. In the present magnetic resonance imaging study, we performed regression analyses to assess hypnotic suggestibility-related differences in local gray matter volume, using voxel-based morphometry, and in waking resting state functional connectivity of 10 resting state networks, in 37 healthy women. Hypnotic suggestibility was positively correlated with gray matter volume in portions of the left superior and medial frontal gyri, roughly overlapping with the supplementary and pre-supplementary motor area, and negatively correlated with gray matter volume in the left superior temporal gyrus and insula. In the functional connectivity analysis, hypnotic suggestibility was positively correlated with functional connectivity between medial posterior areas, including bilateral posterior cingulate cortex and precuneus, and both the lateral visual network and the left fronto-parietal network; a positive correlation was also found with functional connectivity between the executive-control network and a right postcentral/parietal area. In contrast, hypnotic suggestibility was negatively correlated with functional connectivity between the right fronto-parietal network and the right lateral thalamus. These findings demonstrate for the first time a correlation between hypnotic suggestibility, the structural features of specific cortical regions, and the functional connectivity during the normal resting state of brain structures involved in imagery and self-monitoring activity.

Structural and functional cerebral correlates of hypnotic suggestibility.

Science.gov (United States)

Huber, Alexa; Lui, Fausta; Duzzi, Davide; Pagnoni, Giuseppe; Porro, Carlo Adolfo

2014-01-01

Little is known about the neural bases of hypnotic suggestibility, a cognitive trait referring to the tendency to respond to hypnotic suggestions. In the present magnetic resonance imaging study, we performed regression analyses to assess hypnotic suggestibility-related differences in local gray matter volume, using voxel-based morphometry, and in waking resting state functional connectivity of 10 resting state networks, in 37 healthy women. Hypnotic suggestibility was positively correlated with gray matter volume in portions of the left superior and medial frontal gyri, roughly overlapping with the supplementary and pre-supplementary motor area, and negatively correlated with gray matter volume in the left superior temporal gyrus and insula. In the functional connectivity analysis, hypnotic suggestibility was positively correlated with functional connectivity between medial posterior areas, including bilateral posterior cingulate cortex and precuneus, and both the lateral visual network and the left fronto-parietal network; a positive correlation was also found with functional connectivity between the executive-control network and a right postcentral/parietal area. In contrast, hypnotic suggestibility was negatively correlated with functional connectivity between the right fronto-parietal network and the right lateral thalamus. These findings demonstrate for the first time a correlation between hypnotic suggestibility, the structural features of specific cortical regions, and the functional connectivity during the normal resting state of brain structures involved in imagery and self-monitoring activity.

Two-point correlation functions in inhomogeneous and anisotropic cosmologies

International Nuclear Information System (INIS)

Marcori, Oton H.; Pereira, Thiago S.

2017-01-01

Two-point correlation functions are ubiquitous tools of modern cosmology, appearing in disparate topics ranging from cosmological inflation to late-time astrophysics. When the background spacetime is maximally symmetric, invariance arguments can be used to fix the functional dependence of this function as the invariant distance between any two points. In this paper we introduce a novel formalism which fixes this functional dependence directly from the isometries of the background metric, thus allowing one to quickly assess the overall features of Gaussian correlators without resorting to the full machinery of perturbation theory. As an application we construct the CMB temperature correlation function in one inhomogeneous (namely, an off-center LTB model) and two spatially flat and anisotropic (Bianchi) universes, and derive their covariance matrices in the limit of almost Friedmannian symmetry. We show how the method can be extended to arbitrary N -point correlation functions and illustrate its use by constructing three-point correlation functions in some simple geometries.

Two-point correlation functions in inhomogeneous and anisotropic cosmologies

Energy Technology Data Exchange (ETDEWEB)

Marcori, Oton H.; Pereira, Thiago S., E-mail: otonhm@hotmail.com, E-mail: tspereira@uel.br [Departamento de Física, Universidade Estadual de Londrina, 86057-970, Londrina PR (Brazil)

2017-02-01

Two-point correlation functions are ubiquitous tools of modern cosmology, appearing in disparate topics ranging from cosmological inflation to late-time astrophysics. When the background spacetime is maximally symmetric, invariance arguments can be used to fix the functional dependence of this function as the invariant distance between any two points. In this paper we introduce a novel formalism which fixes this functional dependence directly from the isometries of the background metric, thus allowing one to quickly assess the overall features of Gaussian correlators without resorting to the full machinery of perturbation theory. As an application we construct the CMB temperature correlation function in one inhomogeneous (namely, an off-center LTB model) and two spatially flat and anisotropic (Bianchi) universes, and derive their covariance matrices in the limit of almost Friedmannian symmetry. We show how the method can be extended to arbitrary N -point correlation functions and illustrate its use by constructing three-point correlation functions in some simple geometries.

The prevalence and correlates of low sexual functioning in women on hemodialysis: A multinational, cross-sectional study.

Directory of Open Access Journals (Sweden)

Valeria Saglimbene

Full Text Available Sexual dysfunction may affect 80% of women in hemodialysis. However the specific patterns and clinical correlates of sexual functioning remain poorly described. The aim of this study was to assess prevalence and correlates of the individual domains of sexual functioning in women treated with hemodialysis. We recruited, into this multinational cross-sectional study, women treated with long-term hemodialysis (Collaborative Working Group on Depression and Sexual dysfunction in Hemodialysis study. Self-reported domains of sexual functioning were assessed by the Female Sexual Function Index, which is routinely administered within the network of dialysis patients followed by the working group. Lower scores represented lower sexual functioning. Socio-demographic and clinical correlates of each domain of sexual functioning were identified by stepwise multivariable linear regression. Sensitivity analyses were restricted to women who reported being sexually active. We found that of 1309 enrolled women, 659 (50.3% provided complete responses to FSFI survey questions and 232 (35% reported being sexually active. Overall, most respondents reported either no sexual activity or low sexual functioning in all measured domains (orgasm 75.1%; arousal 64.0%; lubrication 63.3%; pain 60.7%; satisfaction 60.1%; sexual desire 58.0%. Respondents who were waitlisted for a kidney transplant reported scores with higher sexual functioning, while older respondents reported scores with lower functioning. The presence of depression was associated with worse lubrication and pain scores [mean difference for depressed versus non-depressed women (95% CI -0.42 (-0.73 to -0.11, -0.53 (-0.89 to -0.16, respectively] while women who had experienced a previous cardiovascular event reported higher pain scores [-0.77 (-1.40- to -0.13]. In conclusion, women in hemodialysis reported scores consistent with marked low sexual functioning across a range of domains; the low functioning appeared

AUTOMATIC EXTRACTION OF ROAD MARKINGS FROM MOBILE LASER SCANNING DATA

Directory of Open Access Journals (Sweden)

H. Ma

2017-09-01

Full Text Available Road markings as critical feature in high-defination maps, which are Advanced Driver Assistance System (ADAS and self-driving technology required, have important functions in providing guidance and information to moving cars. Mobile laser scanning (MLS system is an effective way to obtain the 3D information of the road surface, including road markings, at highway speeds and at less than traditional survey costs. This paper presents a novel method to automatically extract road markings from MLS point clouds. Ground points are first filtered from raw input point clouds using neighborhood elevation consistency method. The basic assumption of the method is that the road surface is smooth. Points with small elevation-difference between neighborhood are considered to be ground points. Then ground points are partitioned into a set of profiles according to trajectory data. The intensity histogram of points in each profile is generated to find intensity jumps in certain threshold which inversely to laser distance. The separated points are used as seed points to region grow based on intensity so as to obtain road mark of integrity. We use the point cloud template-matching method to refine the road marking candidates via removing the noise clusters with low correlation coefficient. During experiment with a MLS point set of about 2 kilometres in a city center, our method provides a promising solution to the road markings extraction from MLS data.

Two-point correlation function for Dirichlet L-functions

Science.gov (United States)

Bogomolny, E.; Keating, J. P.

2013-03-01

The two-point correlation function for the zeros of Dirichlet L-functions at a height E on the critical line is calculated heuristically using a generalization of the Hardy-Littlewood conjecture for pairs of primes in arithmetic progression. The result matches the conjectured random-matrix form in the limit as E → ∞ and, importantly, includes finite-E corrections. These finite-E corrections differ from those in the case of the Riemann zeta-function, obtained in Bogomolny and Keating (1996 Phys. Rev. Lett. 77 1472), by certain finite products of primes which divide the modulus of the primitive character used to construct the L-function in question.

Two-point correlation function for Dirichlet L-functions

International Nuclear Information System (INIS)

Bogomolny, E; Keating, J P

2013-01-01

The two-point correlation function for the zeros of Dirichlet L-functions at a height E on the critical line is calculated heuristically using a generalization of the Hardy–Littlewood conjecture for pairs of primes in arithmetic progression. The result matches the conjectured random-matrix form in the limit as E → ∞ and, importantly, includes finite-E corrections. These finite-E corrections differ from those in the case of the Riemann zeta-function, obtained in Bogomolny and Keating (1996 Phys. Rev. Lett. 77 1472), by certain finite products of primes which divide the modulus of the primitive character used to construct the L-function in question. (paper)

Locality of correlation in density functional theory

Energy Technology Data Exchange (ETDEWEB)

Burke, Kieron [Department of Chemistry, University of California, Irvine, California 92697 (United States); Cancio, Antonio [Department of Physics and Astronomy, Ball State University, Muncie, Indiana 47306 (United States); Gould, Tim [Qld Micro- and Nanotechnology Centre, Griffith University, Nathan, Qld 4111 (Australia); Pittalis, Stefano [CNR-Istituto di Nanoscienze, Via Campi 213A, I-41125 Modena (Italy)

2016-08-07

The Hohenberg-Kohn density functional was long ago shown to reduce to the Thomas-Fermi (TF) approximation in the non-relativistic semiclassical (or large-Z) limit for all matter, i.e., the kinetic energy becomes local. Exchange also becomes local in this limit. Numerical data on the correlation energy of atoms support the conjecture that this is also true for correlation, but much less relevant to atoms. We illustrate how expansions around a large particle number are equivalent to local density approximations and their strong relevance to density functional approximations. Analyzing highly accurate atomic correlation energies, we show that E{sub C} → −A{sub C} ZlnZ + B{sub C}Z as Z → ∞, where Z is the atomic number, A{sub C} is known, and we estimate B{sub C} to be about 37 mhartree. The local density approximation yields A{sub C} exactly, but a very incorrect value for B{sub C}, showing that the local approximation is less relevant for the correlation alone. This limit is a benchmark for the non-empirical construction of density functional approximations. We conjecture that, beyond atoms, the leading correction to the local density approximation in the large-Z limit generally takes this form, but with B{sub C} a functional of the TF density for the system. The implications for the construction of approximate density functionals are discussed.

Obesity is marked by distinct functional connectivity in brain networks involved in food reward and salience.

Science.gov (United States)

Wijngaarden, M A; Veer, I M; Rombouts, S A R B; van Buchem, M A; Willems van Dijk, K; Pijl, H; van der Grond, J

2015-01-01

We hypothesized that brain circuits involved in reward and salience respond differently to fasting in obese versus lean individuals. We compared functional connectivity networks related to food reward and saliency after an overnight fast (baseline) and after a prolonged fast of 48 h in lean versus obese subjects. We included 13 obese (2 males, 11 females, BMI 35.4 ± 1.2 kg/m(2), age 31 ± 3 years) and 11 lean subjects (2 males, 9 females, BMI 23.2 ± 0.5 kg/m(2), age 28 ± 3 years). Resting-state functional magnetic resonance imaging scans were made after an overnight fast (baseline) and after a prolonged 48 h fast. Functional connectivity of the amygdala, hypothalamus and posterior cingulate cortex (default-mode) networks was assessed using seed-based correlations. At baseline, we found a stronger connectivity between hypothalamus and left insula in the obese subjects. This effect diminished upon the prolonged fast. After prolonged fasting, connectivity of the hypothalamus with the dorsal anterior cingulate cortex (dACC) increased in lean subjects and decreased in obese subjects. Amygdala connectivity with the ventromedial prefrontal cortex was stronger in lean subjects at baseline, which did not change upon the prolonged fast. No differences in posterior cingulate cortex connectivity were observed. In conclusion, obesity is marked by alterations in functional connectivity networks involved in food reward and salience. Prolonged fasting differentially affected hypothalamic connections with the dACC and the insula between obese and lean subjects. Our data support the idea that food reward and nutrient deprivation are differently perceived and/or processed in obesity. Copyright © 2015 Elsevier B.V. All rights reserved.

Detecting Near-Earth Objects Using Cross-Correlation with a Point Spread Function

Science.gov (United States)

2009-03-01

impact in the Yucatan Peninsula caused the extinction of the dinosaurs in the Cretaceous Period [Fix, 1995]. Even the Moon is pot marked by many...the atmosphere that the light traverses. For this reason , it is typically better to be at higher elevations to decrease the amount of atmosphere the...detection on average for the Rayleigh sampling with cross-correlation of a PSF than the Rayleigh sampling without cross- correlation. For this reason

Continuous assessment and matriculation examination marks – An empirical examination

Directory of Open Access Journals (Sweden)

Servaas van der Berg

2015-12-01

This study compares CASS data to the externally assessed matric exam marks for a number of subjects. There are two signalling dimensions to inaccurate assessments: (i Inflated CASS marks can give students a false sense of security and lead to diminished exam effort. (ii A weak correlation between CASS and the exam marks could mean poor signalling in another dimension: Relatively good students may get relatively low CASS marks. Such low correlations indicate poor assessment reliability, as the examination and continuous assessment should both be testing mastery of the same national curriculum. The paper analyses the extent of each of these dimensions of weak signalling in South African schools and draws disturbing conclusions for a large part of the school system.

The role of triplet correlation function in dense fluids

International Nuclear Information System (INIS)

Rashid, R.I.M.A.

1993-09-01

In the theory of dense liquids, one usually introduces various correlation functions for describing properties of such systems. It has proved impossible to solve these correlation functions exactly and as such one often resorts to some meaningful approximations for their solutions. It is well known that unless proper precautions are taken, the approximate solutions will violate some useful sum rules and thermodynamic consistency conditions. Here the general rules for generating thermodynamically consistent approximate correlation functions are discussed. The role of triplet correlation is elucidated further by calculating a residual correction to the vacancy formation energy via three-particle correlation in rare gas solids. (author). 16 refs, 4 figs, 1 tab

New real space correlated-basis-functions approach for the electron correlations of the semiconductor inversion layer

International Nuclear Information System (INIS)

Feng Weiguo; Wang Hongwei; Wu Xiang

1989-12-01

Based on the real space Correlated-Basis-Functions theory and the collective oscillation behaviour of the electron gas with effective Coulomb interaction, the many body wave function is obtained for the quasi-two-dimensional electron system in the semiconductor inversion layer. The pair-correlation function and the correlation energy of the system have been calculated by the integro-differential method in this paper. The comparison with the other previous theoretical results is also made. The new theoretical approach and its numerical results show that the pair-correlation functions are definitely positive and satisfy the normalization condition. (author). 10 refs, 2 figs

Redshift distortions of galaxy correlation functions

International Nuclear Information System (INIS)

Fry, J.N.; Florida Univ., Gainesville, FL; Gaztanaga, E.; Oxford Univ.

1993-01-01

To examine how peculiar velocities can affect the 2-, 3-, and 4-point correlation functions, we evaluate volume-average correlations for configurations that emphasize and minimize distortions for four different volume-limited samples from each of the CfA, SSRS, and IRAS redshift catalogs. We present the results as the correlation length r 0 and power index γ of the 2-point correlation, anti Ξ 2 = (r 0 /r) γ , and as the hierarchical amplitudes of the 3- and 4-point functions, S 3 = anti Ξ 3 /anti Ξ 2 2 and S 4 = anti Ξ/anti Ξ 2 3 . We find a characteristic distortion for anti Ξ 2 : The slope γ is flatter and the correlation length is larger in redshift space than in real space; that is, redshift distortions ''move'' correlations from small to large scales. At the largest scales, extra power in the redshift distribution is compatible with Ω 4/7 /b ∼ 1; we find 0.53 ± 0.15, 1.10 ± 0.16 and 0.84 ± 0.45 for the CfA, SSRS and IRAS catalogs. Higher order correlations anti Ξ 3 and anti Ξ 4 suffer similar redshift distortions, but in such a way that, within the accuracy of our analysis, the normalized amplitudes S 3 and S 4 are insensitive to this effect. The hierarchical amplitudes S 3 and S 4 are constant as a function of scale between 1-12 h -1 Mpc and have similar values in all samples and catalogues, S 3 ∼ 2 and S 4 ∼ 6, despite the fact that anti Ξ 2 , anti Ξ 3 , and anti Ξ 4 differ from one sample to another by large factors. The agreement between the independent estimations of S 3 and S 4 is remarkable given the different criteria in the selection of galaxies and also the difference in the resulting range of densities, luminosities and locations between samples

NotaMark industrial laser marking system: a new security marking technology

Science.gov (United States)

Moreau, Vincent G.

2004-06-01

Up until now, the only variable alphanumeric data which could be added to banknotes was the number, applied by means of impact typographical numbering boxes. As an additional process or an alternative to this mechanical method, a non-contact laser marking process can be used offering high quality and greater levels of flexibility. For this purpose KBA-GIORI propose an exclusive laser marking solution called NotaMark. The laser marking process NotaMark is the ideal solution for applying variable data and personalizing banknotes (or any other security documents) with a very high resolution, for extremely large production volumes. A completely integrated solution has been developed comprised of laser light sources, marking head units, and covers and extraction systems. NotaMark allows the marking of variable data by removing locally and selectively, specific printed materials leaving the substrate itself untouched. A wide range of materials has already been tested extensively. NotaMark is a new security feature which is easy to identify and difficult to counterfeit, and which complies with the standard mechanical and chemical resistance tests in the security printing industry as well as with other major soiling tests. The laser marking process opens up a whole new range of design possibilities and can be used to create a primary security feature such as numbering, or to enhance the value of existing features.

Detached and distracted: ERP correlates of altered attentional function in depersonalisation.

Science.gov (United States)

Schabinger, Nadine; Gillmeister, Helge; Berti, Stefan; Michal, Matthias; Beutel, Manfred E; Adler, Julia

2018-04-01

Depersonalisation (DP) is a psychological condition marked by feelings of disembodiment. In everyday life, it is frequently associated with concentration problems. The present study used visual event-related potentials (ERPs) in a Posner-type spatial cueing task with valid, invalid and spatially neutral cues to delineate the potential neurophysiological correlates of these concentration problems. Altered attentional functioning at early, sensory stages was found in DP patients but not in anxiety- and depression-matched psychosomatic patients without DP. Specifically, DP was associated with decreased suppression of stimuli at unattended locations, shown as absent processing costs for invalidly versus neutrally cued stimuli over P1 (135-150 ms). Attentional benefits at N1, and all attentional effects at later, cognitive processing stages (P2-N2, P3) were similar in both groups. We propose that this insufficient early suppression of unattended stimuli may result from atypical sensory gain control in DP. Copyright © 2018 Elsevier B.V. All rights reserved.

A study of correlation functions for the delta-function fermi gas

International Nuclear Information System (INIS)

Berkovich, A.

1987-01-01

In this dissertation, the author considers the quantum nonlinear Schrodinger model, describing a non-relativistic, finite-density gas of one-dimensional fermions with repulsive delta-function interaction. The author employs the quantum inverse scattering method and temperature Green function technique to derive some new results for the two-point, equal-time correlation function. For the case of zero temperature, it is shown that the correlation function in the infinite coupling limit (c → ∞) can be expressed concisely in terms of the solution of the Painleve equation of the fifth kind. The author, then, extends this result and obtains an exact expression for the order (1/c) correction to the two-point function in terms of the Painleve transcendents. This work is essentially self-contained; both old and new results are presented and discussed at some length

The correlation function for density perturbations in an expanding universe. III The three-point and predictions of the four-point and higher order correlation functions

Science.gov (United States)

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.

Measurement of spatial correlation functions using image processing techniques

International Nuclear Information System (INIS)

Berryman, J.G.

1985-01-01

A procedure for using digital image processing techniques to measure the spatial correlation functions of composite heterogeneous materials is presented. Methods for eliminating undesirable biases and warping in digitized photographs are discussed. Fourier transform methods and array processor techniques for calculating the spatial correlation functions are treated. By introducing a minimal set of lattice-commensurate triangles, a method of sorting and storing the values of three-point correlation functions in a compact one-dimensional array is developed. Examples are presented at each stage of the analysis using synthetic photographs of cross sections of a model random material (the penetrable sphere model) for which the analytical form of the spatial correlations functions is known. Although results depend somewhat on magnification and on relative volume fraction, it is found that photographs digitized with 512 x 512 pixels generally have sufficiently good statistics for most practical purposes. To illustrate the use of the correlation functions, bounds on conductivity for the penetrable sphere model are calculated with a general numerical scheme developed for treating the singular three-dimensional integrals which must be evaluated

Alcoholic Hepatitis Markedly Decreases the Capacity for Urea Synthesis.

Directory of Open Access Journals (Sweden)

Emilie Glavind

Full Text Available Data on quantitative metabolic liver functions in the life-threatening disease alcoholic hepatitis are scarce. Urea synthesis is an essential metabolic liver function that plays a key regulatory role in nitrogen homeostasis. The urea synthesis capacity decreases in patients with compromised liver function, whereas it increases in patients with inflammation. Alcoholic hepatitis involves both mechanisms, but how these opposite effects are balanced remains unclear. Our aim was to investigate how alcoholic hepatitis affects the capacity for urea synthesis. We related these findings to another measure of metabolic liver function, the galactose elimination capacity (GEC, as well as to clinical disease severity.We included 20 patients with alcoholic hepatitis and 7 healthy controls. The urea synthesis capacity was quantified by the functional hepatic nitrogen clearance (FHNC, i.e., the slope of the linear relationship between the blood α-amino nitrogen concentration and urea nitrogen synthesis rate during alanine infusion. The GEC was determined using blood concentration decay curves after intravenous bolus injection of galactose. Clinical disease severity was assessed by the Glasgow Alcoholic Hepatitis Score and Model for End-Stage Liver Disease (MELD score.The FHNC was markedly decreased in the alcoholic hepatitis patients compared with the healthy controls (7.2±4.9 L/h vs. 37.4±6.8 L/h, P<0.01, and the largest decrease was observed in those with severe alcoholic hepatitis (4.9±3.6 L/h vs. 9.9±4.9 L/h, P<0.05. The GEC was less markedly reduced than the FHNC. A negative correlation was detected between the FHNC and MELD score (rho = -0.49, P<0.05.Alcoholic hepatitis markedly decreases the urea synthesis capacity. This decrease is associated with an increase in clinical disease severity. Thus, the metabolic failure in alcoholic hepatitis prevails such that the liver cannot adequately perform the metabolic up-regulation observed in other stressful

A partitioned correlation function interaction approach for describing electron correlation in atoms

International Nuclear Information System (INIS)

Verdebout, S; Godefroid, M; Rynkun, P; Jönsson, P; Gaigalas, G; Fischer, C Froese

2013-01-01

The traditional multiconfiguration Hartree–Fock (MCHF) and configuration interaction (CI) methods are based on a single orthonormal orbital basis. For atoms with many closed core shells, or complicated shell structures, a large orbital basis is needed to saturate the different electron correlation effects such as valence, core–valence and correlation within the core shells. The large orbital basis leads to massive configuration state function (CSF) expansions that are difficult to handle, even on large computer systems. We show that it is possible to relax the orthonormality restriction on the orbital basis and break down the originally very large calculations into a series of smaller calculations that can be run in parallel. Each calculation determines a partitioned correlation function (PCF) that accounts for a specific correlation effect. The PCFs are built on optimally localized orbital sets and are added to a zero-order multireference (MR) function to form a total wave function. The expansion coefficients of the PCFs are determined from a low dimensional generalized eigenvalue problem. The interaction and overlap matrices are computed using a biorthonormal transformation technique (Verdebout et al 2010 J. Phys. B: At. Mol. Phys. 43 074017). The new method, called partitioned correlation function interaction (PCFI), converges rapidly with respect to the orbital basis and gives total energies that are lower than the ones from ordinary MCHF and CI calculations. The PCFI method is also very flexible when it comes to targeting different electron correlation effects. Focusing our attention on neutral lithium, we show that by dedicating a PCF to the single excitations from the core, spin- and orbital-polarization effects can be captured very efficiently, leading to highly improved convergence patterns for hyperfine parameters compared with MCHF calculations based on a single orthogonal radial orbital basis. By collecting separately optimized PCFs to correct the

A partitioned correlation function interaction approach for describing electron correlation in atoms

Science.gov (United States)

Verdebout, S.; Rynkun, P.; Jönsson, P.; Gaigalas, G.; Froese Fischer, C.; Godefroid, M.

2013-04-01

The traditional multiconfiguration Hartree-Fock (MCHF) and configuration interaction (CI) methods are based on a single orthonormal orbital basis. For atoms with many closed core shells, or complicated shell structures, a large orbital basis is needed to saturate the different electron correlation effects such as valence, core-valence and correlation within the core shells. The large orbital basis leads to massive configuration state function (CSF) expansions that are difficult to handle, even on large computer systems. We show that it is possible to relax the orthonormality restriction on the orbital basis and break down the originally very large calculations into a series of smaller calculations that can be run in parallel. Each calculation determines a partitioned correlation function (PCF) that accounts for a specific correlation effect. The PCFs are built on optimally localized orbital sets and are added to a zero-order multireference (MR) function to form a total wave function. The expansion coefficients of the PCFs are determined from a low dimensional generalized eigenvalue problem. The interaction and overlap matrices are computed using a biorthonormal transformation technique (Verdebout et al 2010 J. Phys. B: At. Mol. Phys. 43 074017). The new method, called partitioned correlation function interaction (PCFI), converges rapidly with respect to the orbital basis and gives total energies that are lower than the ones from ordinary MCHF and CI calculations. The PCFI method is also very flexible when it comes to targeting different electron correlation effects. Focusing our attention on neutral lithium, we show that by dedicating a PCF to the single excitations from the core, spin- and orbital-polarization effects can be captured very efficiently, leading to highly improved convergence patterns for hyperfine parameters compared with MCHF calculations based on a single orthogonal radial orbital basis. By collecting separately optimized PCFs to correct the MR

First principle approach to correlation functions of spin-1/2 Heisenberg chain: fourth-neighbor correlators

International Nuclear Information System (INIS)

Boos, H.E.; Shiroishi, M.; Takahashi, M.

2005-01-01

We show how correlation functions of the spin-1/2 Heisenberg chain without magnetic field in the anti-ferromagnetic ground state can be explicitly calculated using information contained in the quantum Knizhnik-Zamolodchikov equation [qKZ]. We find several fundamental relations which the inhomogeneous correlations should fulfill. On the other hand, it turns out that these relations can fix the form of the correlations uniquely. Actually, applying this idea, we have obtained all the correlation functions on five sites. Particularly by taking the homogeneous limit, we have got the analytic form of the fourth-neighbor pair correlator j z S j+4 z >

Approximate self-consistent potentials for density-functional-theory exchange-correlation functionals

International Nuclear Information System (INIS)

Cafiero, Mauricio; Gonzalez, Carlos

2005-01-01

We show that potentials for exchange-correlation functionals within the Kohn-Sham density-functional-theory framework may be written as potentials for simpler functionals multiplied by a factor close to unity, and in a self-consistent field calculation, these effective potentials find the correct self-consistent solutions. This simple theory is demonstrated with self-consistent exchange-only calculations of the atomization energies of some small molecules using the Perdew-Kurth-Zupan-Blaha (PKZB) meta-generalized-gradient-approximation (meta-GGA) exchange functional. The atomization energies obtained with our method agree with or surpass previous meta-GGA calculations performed in a non-self-consistent manner. The results of this work suggest the utility of this simple theory to approximate exchange-correlation potentials corresponding to energy functionals too complicated to generate closed forms for their potentials. We hope that this method will encourage the development of complex functionals which have correct boundary conditions and are free of self-interaction errors without the worry that the functionals are too complex to differentiate to obtain potentials

Lifetime information from correlation functions selected by directional cuts

International Nuclear Information System (INIS)

Gelbke, C.K.

1995-01-01

Two-particle correlation functions provide information on the space-time characteristics of the emitting source. In many cases, ambiguities of the relative magnitudes of source radius and lifetime can be reduced by analysis of correlation functions evaluated for specific directional cuts on the relative velocity of the coincident particle pair. Information on non-spherical breakup geometries is more difficult to extract. Examples of two-proton correlation functions in which directional cuts are employed to reduce existing space-time ambiguities for the emitting system are presented. (author). 50 refs., 10 figs

A test of conformal invariance: Correlation functions on a disk

International Nuclear Information System (INIS)

Badke, R.; Rittenberg, V.; Ruegg, H.

1985-06-01

Using conformal invariance one can derive the correlation functions of a disk from those in the half-plane. The correlation function in the half-plane is determined by the 'small' conformal invariance up to an unknown function of one variable. By measuring through the Monte Carlo method the correlation function for two different configurations, the unknown function can be eliminated and one obtains a test of conformal invariance. It is shown that the Ising and the three state Potts model pass the test for very small lattices. (orig.)

Demographic and Parenting Correlates of Adolescent Sleep Functioning.

Science.gov (United States)

Zapata Roblyer, Martha I; Grzywacz, Joseph G

2015-11-01

Despite the importance of parenting practices for adolescent adjustment, parenting correlates of adolescent sleep functioning remain understudied. This study delineated patterns of sleep functioning in a sample of ethnically diverse, low-income, adolescents and examined associations among three types of parenting practices (parental involvement, parent-child conflict, and parental control) and adolescent sleep functioning (difficulties initiating sleep and maintaining sleep, and sleep duration). Adolescents ( N = 91, 11-19 years old) self-reported on sleep functioning and parenting practices. Results showed that in the preceding month, 60.5% of adolescents had difficulties initiating sleep and 73.6% had difficulties maintaining sleep. Most adolescents slept 8 or more hours per night, but 30.7% slept less than 8 hours. Latino adolescents slept longer and had fewer difficulties maintaining sleep than non-Latino. High school students had fewer difficulties maintaining sleep than their middle school counterparts; conversely, older adolescents experienced shorter sleep duration than younger ones. Adolescents whose parents had post-secondary education had shorter sleep duration than those whose parents had not graduated from high school. Parental control was correlated with fewer difficulties initiating sleep, whereas parent-child conflict was correlated with more difficulties maintaining sleep. There were no parenting correlates of sleep duration. Latino adolescents had better sleep profiles than non-Latino ones. Regression analyses showed that parental control and parent-child conflict were associated with adolescent sleep functioning across ethnicities. Results suggest that parenting practices, as well as demographic characteristics, are associated with adolescent sleep functioning and should be taken into account in interventions aimed at improving sleep functioning among adolescents.

Elucidation of spin echo small angle neutron scattering correlation functions through model studies.

Science.gov (United States)

Shew, Chwen-Yang; Chen, Wei-Ren

2012-02-14

Several single-modal Debye correlation functions to approximate part of the overall Debey correlation function of liquids are closely examined for elucidating their behavior in the corresponding spin echo small angle neutron scattering (SESANS) correlation functions. We find that the maximum length scale of a Debye correlation function is identical to that of its SESANS correlation function. For discrete Debye correlation functions, the peak of SESANS correlation function emerges at their first discrete point, whereas for continuous Debye correlation functions with greater width, the peak position shifts to a greater value. In both cases, the intensity and shape of the peak of the SESANS correlation function are determined by the width of the Debye correlation functions. Furthermore, we mimic the intramolecular and intermolecular Debye correlation functions of liquids composed of interacting particles based on a simple model to elucidate their competition in the SESANS correlation function. Our calculations show that the first local minimum of a SESANS correlation function can be negative and positive. By adjusting the spatial distribution of the intermolecular Debye function in the model, the calculated SESANS spectra exhibit the profile consistent with that of hard-sphere and sticky-hard-sphere liquids predicted by more sophisticated liquid state theory and computer simulation. © 2012 American Institute of Physics

Correlation between hypertension and cognitive function in elderly

Science.gov (United States)

Fitri, F. I.; Rambe, A. S.

2018-03-01

Hypertension and cognitive impairment are common disorders among elderly adults, and their prevalences tend to rise as the population ages. This study aimed to determine the correlation between hypertension and cognitive function in elderly. It was a cross-sectional study involving 62 elderly subjects. All subjects underwent physical and neurologic examination and Montreal Cognitive Assessment-Indonesian Version (MoCA-INA) to assess cognitive function. This study included 62 subjects consisted of 26 males (41.9%) and 36 females (58.1%). There were 24 subjects (38.2%) with hypertension and 38 (61.3%) normal elderly subjects. The mean age was 65.71±4.49 years old. There were no significant differences in demographic characteristics, total MoCA-INA scores, and scores based on cognitive domains between two groups, except for visuospatial and executive function (p=0.026). There was a significant correlation between hypertension and visuospatial and executive function (r=0.301, p=0.017). Hypertension is correlated with cognitive impairment mainly on visuospatial and executive function in elderly.

Subsystem density functional theory with meta-generalized gradient approximation exchange-correlation functionals.

Science.gov (United States)

Śmiga, Szymon; Fabiano, Eduardo; Laricchia, Savio; Constantin, Lucian A; Della Sala, Fabio

2015-04-21

We analyze the methodology and the performance of subsystem density functional theory (DFT) with meta-generalized gradient approximation (meta-GGA) exchange-correlation functionals for non-bonded molecular systems. Meta-GGA functionals depend on the Kohn-Sham kinetic energy density (KED), which is not known as an explicit functional of the density. Therefore, they cannot be directly applied in subsystem DFT calculations. We propose a Laplacian-level approximation to the KED which overcomes this limitation and provides a simple and accurate way to apply meta-GGA exchange-correlation functionals in subsystem DFT calculations. The so obtained density and energy errors, with respect to the corresponding supermolecular calculations, are comparable with conventional approaches, depending almost exclusively on the approximations in the non-additive kinetic embedding term. An embedding energy error decomposition explains the accuracy of our method.

Correlation functions of warped CFT

Science.gov (United States)

Song, Wei; Xu, Jianfei

2018-04-01

Warped conformal field theory (WCFT) is a two dimensional quantum field theory whose local symmetry algebra consists of a Virasoro algebra and a U(1) Kac-Moody algebra. In this paper, we study correlation functions for primary operators in WCFT. Similar to conformal symmetry, warped conformal symmetry is very constraining. The form of the two and three point functions are determined by the global warped conformal symmetry while the four point functions can be determined up to an arbitrary function of the cross ratio. The warped conformal bootstrap equation are constructed by formulating the notion of crossing symmetry. In the large central charge limit, four point functions can be decomposed into global warped conformal blocks, which can be solved exactly. Furthermore, we revisit the scattering problem in warped AdS spacetime (WAdS), and give a prescription on how to match the bulk result to a WCFT retarded Green's function. Our result is consistent with the conjectured holographic dualities between WCFT and WAdS.

Correlation Functions in Holographic Minimal Models

CERN Document Server

Papadodimas, Kyriakos

2012-01-01

We compute exact three and four point functions in the W_N minimal models that were recently conjectured to be dual to a higher spin theory in AdS_3. The boundary theory has a large number of light operators that are not only invisible in the bulk but grow exponentially with N even at small conformal dimensions. Nevertheless, we provide evidence that this theory can be understood in a 1/N expansion since our correlators look like free-field correlators corrected by a power series in 1/N . However, on examining these corrections we find that the four point function of the two bulk scalar fields is corrected at leading order in 1/N through the contribution of one of the additional light operators in an OPE channel. This suggests that, to correctly reproduce even tree-level correlators on the boundary, the bulk theory needs to be modified by the inclusion of additional fields. As a technical by-product of our analysis, we describe two separate methods -- including a Coulomb gas type free-field formalism -- that ...

Scaling behaviour of the correlation length for the two-point correlation function in the random field Ising chain

Energy Technology Data Exchange (ETDEWEB)

Lange, Adrian; Stinchcombe, Robin [Theoretical Physics, University of Oxford, Oxford (United Kingdom)

1996-07-07

We study the general behaviour of the correlation length {zeta}(kT:h) for two-point correlation function of the local fields in an Ising chain with binary distributed fields. At zero field it is shown that {zeta} is the same as the zero-field correlation length for the spin-spin correlation function. For the field-dominated behaviour of {zeta} we find an exponent for the power-law divergence which is smaller than the exponent for the spin-spin correlation length. The entire behaviour of the correlation length can be described by a single crossover scaling function involving the new critical exponent. (author)

Construction of exchange-correlation functionals through interpolation between the non-interacting and the strong-correlation limit

International Nuclear Information System (INIS)

Zhou, Yongxi; Ernzerhof, Matthias; Bahmann, Hilke

2015-01-01

Drawing on the adiabatic connection of density functional theory, exchange-correlation functionals of Kohn-Sham density functional theory are constructed which interpolate between the extreme limits of the electron-electron interaction strength. The first limit is the non-interacting one, where there is only exchange. The second limit is the strong correlated one, characterized as the minimum of the electron-electron repulsion energy. The exchange-correlation energy in the strong-correlation limit is approximated through a model for the exchange-correlation hole that is referred to as nonlocal-radius model [L. O. Wagner and P. Gori-Giorgi, Phys. Rev. A 90, 052512 (2014)]. Using the non-interacting and strong-correlated extremes, various interpolation schemes are presented that yield new approximations to the adiabatic connection and thus to the exchange-correlation energy. Some of them rely on empiricism while others do not. Several of the proposed approximations yield the exact exchange-correlation energy for one-electron systems where local and semi-local approximations often fail badly. Other proposed approximations generalize existing global hybrids by using a fraction of the exchange-correlation energy in the strong-correlation limit to replace an equal fraction of the semi-local approximation to the exchange-correlation energy in the strong-correlation limit. The performance of the proposed approximations is evaluated for molecular atomization energies, total atomic energies, and ionization potentials

Two Point Correlation Functions for a Periodic Box-Ball System

Directory of Open Access Journals (Sweden)

Jun Mada

2011-03-01

Full Text Available We investigate correlation functions in a periodic box-ball system. For the second and the third nearest neighbor correlation functions, we give explicit formulae obtained by combinatorial methods. A recursion formula for a specific N-point functions is also presented.

DSN Beowulf Cluster-Based VLBI Correlator

Science.gov (United States)

Rogstad, Stephen P.; Jongeling, Andre P.; Finley, Susan G.; White, Leslie A.; Lanyi, Gabor E.; Clark, John E.; Goodhart, Charles E.

2009-01-01

The NASA Deep Space Network (DSN) requires a broadband VLBI (very long baseline interferometry) correlator to process data routinely taken as part of the VLBI source Catalogue Maintenance and Enhancement task (CAT M&E) and the Time and Earth Motion Precision Observations task (TEMPO). The data provided by these measurements are a crucial ingredient in the formation of precision deep-space navigation models. In addition, a VLBI correlator is needed to provide support for other VLBI related activities for both internal and external customers. The JPL VLBI Correlator (JVC) was designed, developed, and delivered to the DSN as a successor to the legacy Block II Correlator. The JVC is a full-capability VLBI correlator that uses software processes running on multiple computers to cross-correlate two-antenna broadband noise data. Components of this new system (see Figure 1) consist of Linux PCs integrated into a Beowulf Cluster, an existing Mark5 data storage system, a RAID array, an existing software correlator package (SoftC) originally developed for Delta DOR Navigation processing, and various custom- developed software processes and scripts. Parallel processing on the JVC is achieved by assigning slave nodes of the Beowulf cluster to process separate scans in parallel until all scans have been processed. Due to the single stream sequential playback of the Mark5 data, some ramp-up time is required before all nodes can have access to required scan data. Core functions of each processing step are accomplished using optimized C programs. The coordination and execution of these programs across the cluster is accomplished using Pearl scripts, PostgreSQL commands, and a handful of miscellaneous system utilities. Mark5 data modules are loaded on Mark5 Data systems playback units, one per station. Data processing is started when the operator scans the Mark5 systems and runs a script that reads various configuration files and then creates an experiment-dependent status database

Correlations in Many-Body systems from two-time Greens functions

International Nuclear Information System (INIS)

Morawetz, K.; Kohler, H.S.

2000-01-01

The Kadanoff-Baym (KB) equations are solved numerically for infinite nuclear matter. In particular we calculate correlation energies and correlation times. Approximating the Green's functions in the KB collision kernel by the free Green's functions the Levinson equation is obtained. This approximation is valid for weak interactions and/or low densities. It relates to the extended quasi-particle approximation for the spectral function. The Levinson correlation energy reduces for large times to a second order Born approximation for the energy. Comparing the Levinson, Born and KB calculations allows for an estimate of higher order spectral corrections to the correlations. (authors)

BWR Mark I pressure suppression study: characterization of the vertical load function utilizing bench top model tests

International Nuclear Information System (INIS)

McCauley, E.W.; Lai, W.

1977-02-01

A study was conducted to characterize the mechanisms which give rise to observed oscillations in the vertical load function (VLF) of bench top pool dynamics tests. This is part of a continuing investigation at the Lawrence Livermore Laboratory of the General Electric Mark I Nuclear Reactor pressure suppression system

On the application of correlation function matrices in OMA

DEFF Research Database (Denmark)

Brincker, Rune

2017-01-01

In this paper the theoretical solution for the correlation function matrix of the random response of a structural system is re-visited. It is shown that using the classical definition of the correlation functions, the row space is defined by the mode shapes of the system, whereas the column space...

Long-time tails of correlation and memory functions

Science.gov (United States)

Sawada, Isao

2002-11-01

We review the generalized Langevin equation, which is a transformation and reformulation of equation of motion, from the two viewpoints: the projection operator method developed by Mori and the recurrence relations method developed by Lee. The fluctuating forces acting on the Bloch electrons’ current are clarified the strongly colored quantum fluctuations with the spontaneous interband transitions leading to a long-time tail of 1/ t for the envelope of the memory function. The velocity autocorrelation functions in the coupled harmonic oscillator on the Bethe lattice have a long-time tail of 1/t t. The oscillation and the form of decay found in correlation functions affect transport coefficients given by the integrated intensity up to infinity. We also study the force-force correlation functions often used as an approximation to the memory function.

Cumulant approach to dynamical correlation functions at finite temperatures

International Nuclear Information System (INIS)

Tran Minhtien.

1993-11-01

A new theoretical approach, based on the introduction of cumulants, to calculate thermodynamic averages and dynamical correlation functions at finite temperatures is developed. The method is formulated in Liouville instead of Hilbert space and can be applied to operators which do not require to satisfy fermion or boson commutation relations. The application of the partitioning and projection methods for the dynamical correlation functions is discussed. The present method can be applied to weakly as well as to strongly correlated systems. (author). 9 refs

Strong Correlation in Kohn-Sham Density Functional Theory

NARCIS (Netherlands)

Malet, F.; Gori Giorgi, P.

2012-01-01

We use the exact strong-interaction limit of the Hohenberg-Kohn energy density functional to approximate the exchange-correlation energy of the restricted Kohn-Sham scheme. Our approximation corresponds to a highly nonlocal density functional whose functional derivative can be easily constructed,

Method of vacuum correlation functions: Results and prospects

International Nuclear Information System (INIS)

Badalian, A. M.; Simonov, Yu. A.; Shevchenko, V. I.

2006-01-01

Basic results obtained within the QCD method of vacuum correlation functions over the past 20 years in the context of investigations into strong-interaction physics at the Institute of Theoretical and Experimental Physics (ITEP, Moscow) are formulated Emphasis is placed primarily on the prospects of the general theory developed within QCD by employing both nonperturbative and perturbative methods. On the basis of ab initio arguments, it is shown that the lowest two field correlation functions play a dominant role in QCD dynamics. A quantitative theory of confinement and deconfinement, as well as of the spectra of light and heavy quarkonia, glueballs, and hybrids, is given in terms of these two correlation functions. Perturbation theory in a nonperturbative vacuum (background perturbation theory) plays a significant role, not possessing drawbacks of conventional perturbation theory and leading to the infrared freezing of the coupling constant α s

Correlation functions for Hermitian many-body systems: Necessary conditions

International Nuclear Information System (INIS)

Brown, E.B.

1994-01-01

Lee [Phys. Rev. B 47, 8293 (1993)] has shown that the odd-numbered derivatives of the Kubo autocorrelation function vanish at t=0. We show that this condition is based on a more general property of nondiagonal Kubo correlation functions. This general property provides that certain functional forms (e.g., simple exponential decay) are not admissible for any symmetric or antisymmetric Kubo correlation function in a Hermitian many-body system. Lee's result emerges as a special case of this result. Applications to translationally invariant systems and systems with rotational symmetries are also demonstrated

Neural correlates of executive functions in patients with obesity.

Science.gov (United States)

Ho, Ming-Chou; Chen, Vincent Chin-Hung; Chao, Seh-Huang; Fang, Ching-Tzu; Liu, Yi-Chun; Weng, Jun-Cheng

2018-01-01

Obesity is one of the most challenging problems in human health and is recognized as an important risk factor for many chronic diseases. It remains unclear how the neural systems (e.g., the mesolimbic "reward" and the prefrontal "control" neural systems) are correlated with patients' executive function (EF), conceptualized as the integration of "cool" EF and "hot" EF. "Cool" EF refers to relatively abstract, non-affective operations such as inhibitory control and mental flexibility. "Hot" EF refers to motivationally significant affective operations such as affective decision-making. We tried to find the correlation between structural and functional neuroimaging indices and EF in obese patients. The study population comprised seventeen patients with obesity (seven males and 10 females, BMI = 37.99 ± 5.40, age = 31.82 ± 8.75 year-old) preparing to undergo bariatric surgery. We used noninvasive diffusion tensor imaging, generalized q-sampling imaging, and resting-state functional magnetic resonance imaging to examine the neural correlations between structural and functional neuroimaging indices and EF performances in patients with obesity. We reported that many brain areas are correlated to the patients' EF performances. More interestingly, some correlations may implicate the possible associations of EF and the incentive motivational effects of food. The neural correlation between the left precuneus and middle occipital gyrus and inhibitory control may suggest that patients with a better ability to detect appetitive food may have worse inhibitory control. Also, the neural correlation between the superior frontal blade and affective decision-making may suggest that patients' affective decision-making may be associated with the incentive motivational effects of food. Our results provide evidence suggesting neural correlates of EF in patients with obesity.

Universality of correlation functions in random matrix models of QCD

International Nuclear Information System (INIS)

Jackson, A.D.; Sener, M.K.; Verbaarschot, J.J.M.

1997-01-01

We demonstrate the universality of the spectral correlation functions of a QCD inspired random matrix model that consists of a random part having the chiral structure of the QCD Dirac operator and a deterministic part which describes a schematic temperature dependence. We calculate the correlation functions analytically using the technique of Itzykson-Zuber integrals for arbitrary complex supermatrices. An alternative exact calculation for arbitrary matrix size is given for the special case of zero temperature, and we reproduce the well-known Laguerre kernel. At finite temperature, the microscopic limit of the correlation functions are calculated in the saddle-point approximation. The main result of this paper is that the microscopic universality of correlation functions is maintained even though unitary invariance is broken by the addition of a deterministic matrix to the ensemble. (orig.)

Four-body correlation embedded in antisymmetrized geminal power wave function.

Science.gov (United States)

Kawasaki, Airi; Sugino, Osamu

2016-12-28

We extend the Coleman's antisymmetrized geminal power (AGP) to develop a wave function theory that can incorporate up to four-body correlation in a region of strong correlation. To facilitate the variational determination of the wave function, the total energy is rewritten in terms of the traces of geminals. This novel trace formula is applied to a simple model system consisting of one dimensional Hubbard ring with a site of strong correlation. Our scheme significantly improves the result obtained by the AGP-configuration interaction scheme of Uemura et al. and also achieves more efficient compression of the degrees of freedom of the wave function. We regard the result as a step toward a first-principles wave function theory for a strongly correlated point defect or adsorbate embedded in an AGP-based mean-field medium.

Correlation functions of one-dimensional Lieb-Liniger anyons

International Nuclear Information System (INIS)

Patu, Ovidiu I; Korepin, Vladimir E; Averin, Dmitri V

2007-01-01

We have investigated the properties of a model of 1D anyons interacting through a δ-function repulsive potential. The structure of the quasi-periodic boundary conditions for the anyonic field operators and the many-anyon wavefunctions is clarified. The spectrum of the low-lying excitations including the particle-hole excitations is calculated for periodic and twisted boundary conditions. Using the ideas of the conformal field theory we obtain the large-distance asymptotics of the density and field correlation function at the critical temperature T = 0 and at small finite temperatures. Our expression for the field correlation function extends the results in the literature obtained for harmonic quantum anyonic fluids

Liquid ammonia: Molecular correlation functions from x-ray diffraction

International Nuclear Information System (INIS)

Narten, A.H.

1977-01-01

For nearly spherical molecules the x-ray scattering from liquids yields structure and correlation functions for molecular centers. The distribution of electron density in an ammonia molecular is very nearly spherical, and orientational correlation between molecules in the liquid is not ''seen'' by x rays. Structure and correlation functions for molecular centers (nitrogen atoms) are derived from x-ray data on liquid NH 3 at 4 degreeC and tabulated. They provide a sensitive test for future work on a molecular theory of liquid ammonia

Efficient quantum algorithm for computing n-time correlation functions.

Science.gov (United States)

Pedernales, J S; Di Candia, R; Egusquiza, I L; Casanova, J; Solano, E

2014-07-11

We propose a method for computing n-time correlation functions of arbitrary spinorial, fermionic, and bosonic operators, consisting of an efficient quantum algorithm that encodes these correlations in an initially added ancillary qubit for probe and control tasks. For spinorial and fermionic systems, the reconstruction of arbitrary n-time correlation functions requires the measurement of two ancilla observables, while for bosonic variables time derivatives of the same observables are needed. Finally, we provide examples applicable to different quantum platforms in the frame of the linear response theory.

Correlation function of gravitational deflection angles of light paths

International Nuclear Information System (INIS)

Watanabe, Kazuya; Tomita, Kenji.

1990-04-01

The correlation function of gravitational deflection angles of light paths is investigated in a simplified cosmological model universe. Under several reasonable assumptions, an analytic formula for the correlation function is derived. The implication to the cosmic microwave background anisotropy and the distance defined by the observed angular (linear) scale of a source is also discussed. (author)

Two-proton correlation functions for equilibrium and non-equilibrium emission

International Nuclear Information System (INIS)

Gong, W.G.; Gelbke, C.K.; Carlin, N.; De Souza, R.T.; Kim, Y.D.; Lynch, W.G.; Murakami, T.; Poggi, G.; Sanderson, D.; Tsang, M.B.; Xu, H.M.; Michigan State Univ., East Lansing; Fields, D.E.; Kwiatkowski, K.; Planeta, R.; Viola, V.E. Jr.; Yennello, S.J.; Indiana Univ., Bloomington; Indiana Univ., Bloomington; Pratt, S.

1990-01-01

Two-proton correlation functions are compared for equilibrium and non-equilibrium emission processes investigated, respectively, in ''reverse kinematics'' for the reactions 129 Xe+ 27 Al and 129 Xe+ 122 Sn at E/A=31 MeV and in ''forward kinematics'' for the reaction 14 N+ 197 Au at E/A=75 MeV. Observed differences in the shapes of the correlation functions are understood in terms of the different time scales for equilibrium and preequilibrium emission. Transverse and longitudinal correlation functions are very similar. (orig.)

Correlation between Lymphocyte CD4 Count, Treatment Duration, Opportunistic Infection and Cognitive Function in Human Immunodeficiency Virus-Acquired Immunodeficiency Syndrome (HIV-AIDS) Patients.

Science.gov (United States)

Fitri, Fasihah Irfani; Rambe, Aldy Safruddin; Fitri, Aida

2018-04-15

Human immunodeficiency virus (HIV) infection is an epidemic worldwide, despite the marked benefits of antiretroviral therapy (ARV) in reducing severe HIV-associated dementia. A milder form of neurocognitive disorders are still prevalent and remain a challenge. This study aimed to determine the correlation between plasma cluster of differentiation 4 (CD4) lymphocyte, duration of ARV treatment, opportunistic infections, and cognitive function in HIV-AIDS patients. A cross-sectional study involving 85 HIV-AIDS patients was conducted at Adam Malik General Hospital Medan, Indonesia. All subjects were subjected to physical, neurologic examination and Montreal Cognitive Assessment-Indonesian Version (MoCA-INA) to assess cognitive function and measurement of lymphocyte CD4 counts. Out of the 85 subjects evaluated, the proportion concerning sexes include 52 males (61.2 %) and 33 females (38.8%). The mean age was 38.53 ± 9.77 years old. There was a significant correlation between CD4 lymphocyte counts and MoCA-INA score (r = 0.271, p = 0.012), but there was no significant correlation between duration of ARV treatment and MoCA-INA score. There was also no difference in MoCA-INA score based on the presence of opportunistic infection. Lymphocyte CD4 count was independently correlated with cognitive function in HIV-AIDS patients.

Universal Spatial Correlation Functions for Describing and Reconstructing Soil Microstructure

Science.gov (United States)

Skvortsova, Elena B.; Mallants, Dirk

2015-01-01

Structural features of porous materials such as soil define the majority of its physical properties, including water infiltration and redistribution, multi-phase flow (e.g. simultaneous water/air flow, or gas exchange between biologically active soil root zone and atmosphere) and solute transport. To characterize soil microstructure, conventional soil science uses such metrics as pore size and pore-size distributions and thin section-derived morphological indicators. However, these descriptors provide only limited amount of information about the complex arrangement of soil structure and have limited capability to reconstruct structural features or predict physical properties. We introduce three different spatial correlation functions as a comprehensive tool to characterize soil microstructure: 1) two-point probability functions, 2) linear functions, and 3) two-point cluster functions. This novel approach was tested on thin-sections (2.21×2.21 cm2) representing eight soils with different pore space configurations. The two-point probability and linear correlation functions were subsequently used as a part of simulated annealing optimization procedures to reconstruct soil structure. Comparison of original and reconstructed images was based on morphological characteristics, cluster correlation functions, total number of pores and pore-size distribution. Results showed excellent agreement for soils with isolated pores, but relatively poor correspondence for soils exhibiting dual-porosity features (i.e. superposition of pores and micro-cracks). Insufficient information content in the correlation function sets used for reconstruction may have contributed to the observed discrepancies. Improved reconstructions may be obtained by adding cluster and other correlation functions into reconstruction sets. Correlation functions and the associated stochastic reconstruction algorithms introduced here are universally applicable in soil science, such as for soil classification

Correlation between HRCT and pulmonary functional tests in cystic fibrosis

International Nuclear Information System (INIS)

Mastellari, Paola; Biggi, Simona; Lombardi, Alfonsa; Zompatori, Maurizio; Grzincich, Gianluigi; Pisi, Giovanna; Spaggiari, Cinzia

2005-01-01

Purpose. To compare the HRCT score by Oikonottlou and air trapping in expiratory scans with pulmonary functional tests and evaluate which radiological criteria are more useful to predict clinical impairment. Materials and methods. From January to September 2003, pulmonary HRCT study was performed in 37 patients (23 males), aged between 7 and 41 years, with cystic fibrosis. In the same day of CT examination they also received a complete functional evaluation. HRCT studies were evaluated by three radiologists blinded to the clinical data and were correlated with the lung function tests. Results. We obtained a high correlation (p=0.01) for two of the HRCT signs: extent of mucus plugging and mosaic perfusion pattern and all function tests. Discussion. Previous studies have demonstrated good correlation between lung function tests, in particular with FEV1 and HRCT signs. Our study differed from previous ones in that we analysed the correlation between lung function tests and with both single and combined CT criteria. Conclusion. Our results suggest that a simplified HRCT store could be useful to evaluate patients with cystic fibrosis [it

Bulk stress auto-correlation function in simple liquids-sum rules

International Nuclear Information System (INIS)

Tankeshwar, K.; Bhandari, R.; Pathak, K.N.

1990-10-01

Expressions for the zeroth, second and fourth frequency sum rules of the bulk stress auto correlation function have been derived. The exact expressions involve static correlation function up to four particles. Because of the non availability of any information about static quadruplet correlation function we use a low order decoupling approximation for this. In this work, we have obtained, separately, the sum rules for the different mechanism of momentum transfer in the fluids. The results are expected to be useful in the study of bulk viscosity of the fluids. (author). 9 refs

Non-Parametric Estimation of Correlation Functions

DEFF Research Database (Denmark)

Brincker, Rune; Rytter, Anders; Krenk, Steen

In this paper three methods of non-parametric correlation function estimation are reviewed and evaluated: the direct method, estimation by the Fast Fourier Transform and finally estimation by the Random Decrement technique. The basic ideas of the techniques are reviewed, sources of bias are point...

Material correlations and models for the irradiation behavior of fissile and fertile material in SNR-300, Mark-II and KNK II, third core

International Nuclear Information System (INIS)

Fenneker; Steinmetz; Toebbe

1986-07-01

The report contains the material correlations and models used in the fuel pin design code IAMBUS for the irradiation behavior of PuO 2 -UO 2 fissile materials and UO 2 fertile materials of the SNR-300 Mark-II reload and the KNK II third core. They are applicable for pellet densities of more than 90 % of the theoretical density. The presented models of the fuel behavior and the applied material correlations have been derived either from single experiments or from the comparison of theoretically predicted integral fuel behavior with the results of fuel pin irradiation experiments. The material correlations have been examined and extended in the frame of the collaborations INTERATOM/KWU and INTERATOM/KfK. French and British results were included, when available from the European fast reactor knowledge exchange [de

Response of the oxygen uptake efficiency slope to orthotopic heart transplantation: lack of correlation with changes in central hemodynamic parameters and resting lung function.

Science.gov (United States)

Van Laethem, Christophe; Goethals, Marc; Verstreken, Sofie; Walravens, Maarten; Wellens, Francis; De Proft, Margot; Bartunek, Jozef; Vanderheyden, Marc

2007-09-01

Recently, a new linear measure of ventilatory response to exercise, the oxygen uptake efficiency slope (OUES), was proposed in the evaluation of heart failure patients. No data are available on the response of the OUES after orthotopic heart transplantation (HTx). Thirty patients who underwent HTx between 1999 and 2003 were included in the study. Data from maximal cardiopulmonary exercise test, resting pulmonary function and hemodynamic assessment were collected before the transplant at time of screening and 1 year after HTx. During the first year after HTx, OUES and normalized OUES for body weight (OUES/kg) increased significantly from 15.6 +/- 4.9 to 19.7 +/- 4.8 (p volumes or capacities and measures of central hemodynamic function after HTx. OUES improved significantly after HTx, but, similar to other exercise parameters, remained considerably impaired. The changes in OUES were highly correlated with the improvements in other exercise variables, but did not correlate with marked improvements in central hemodynamics or resting lung function.

Rotational Invariance of the 2d Spin - Spin Correlation Function

Science.gov (United States)

Pinson, Haru

2012-09-01

At the critical temperature in the 2d Ising model on the square lattice, we establish the rotational invariance of the spin-spin correlation function using the asymptotics of the spin-spin correlation function along special directions (McCoy and Wu in the two dimensional Ising model. Harvard University Press, Cambridge, 1973) and the finite difference Hirota equation for which the spin-spin correlation function is shown to satisfy (Perk in Phys Lett A 79:3-5, 1980; Perk in Proceedings of III international symposium on selected topics in statistical mechanics, Dubna, August 22-26, 1984, JINR, vol II, pp 138-151, 1985).

The heat current density correlation function: sum rules and thermal conductivity

International Nuclear Information System (INIS)

Singh, Shaminder; Tankeshwar, K; Pathak, K N; Ranganathan, S

2006-01-01

Expressions for the second and fourth sum rules of the heat current density correlation function have been derived in an appropriate ensemble. The thermal conductivity of Lennard-Jones fluids has been calculated using these sum rules for the heat current density correlation function and the Gaussian form of the memory function. It is found that the results obtained for the thermal conductivity are in good agreement with the molecular dynamics simulation results over a wide range of densities and temperatures. Earlier results obtained using the energy current density correlation function are also discussed

The heat current density correlation function: sum rules and thermal conductivity

Energy Technology Data Exchange (ETDEWEB)

Singh, Shaminder [Department of Physics, Panjab University, Chandigarh-160 014 (India); Tankeshwar, K [Department of Physics, Panjab University, Chandigarh-160 014 (India); Pathak, K N [Department of Physics, Panjab University, Chandigarh-160 014 (India); Ranganathan, S [Department of Physics, Royal Military College, Kingston, ON, K7K 7B4 (Canada)

2006-02-01

Expressions for the second and fourth sum rules of the heat current density correlation function have been derived in an appropriate ensemble. The thermal conductivity of Lennard-Jones fluids has been calculated using these sum rules for the heat current density correlation function and the Gaussian form of the memory function. It is found that the results obtained for the thermal conductivity are in good agreement with the molecular dynamics simulation results over a wide range of densities and temperatures. Earlier results obtained using the energy current density correlation function are also discussed.

Cross-Correlation-Function-Based Multipath Mitigation Method for Sine-BOC Signals

Directory of Open Access Journals (Sweden)

H. H. Chen

2012-06-01

Full Text Available Global Navigation Satellite Systems (GNSS positioning accuracy indoor and urban canyons environments are greatly affected by multipath due to distortions in its autocorrelation function. In this paper, a cross-correlation function between the received sine phased Binary Offset Carrier (sine-BOC modulation signal and the local signal is studied firstly, and a new multipath mitigation method based on cross-correlation function for sine-BOC signal is proposed. This method is implemented to create a cross-correlation function by designing the modulated symbols of the local signal. The theoretical analysis and simulation results indicate that the proposed method exhibits better multipath mitigation performance compared with the traditional Double Delta Correlator (DDC techniques, especially the medium/long delay multipath signals, and it is also convenient and flexible to implement by using only one correlator, which is the case of low-cost mass-market receivers.

Correlation functions of the Ising model and the eight-vertex model

International Nuclear Information System (INIS)

Ko, L.F.

1986-01-01

Calculations for the two-point correlation functions in the scaling limit for two statistical models are presented. In Part I, the Ising model with a linear defect is studied for T T/sub c/. The transfer matrix method of Onsager and Kaufman is used. The energy-density correlation is given by functions related to the modified Bessel functions. The dispersion expansion for the spin-spin correlation functions are derived. The dominant behavior for large separations at T not equal to T/sub c/ is extracted. It is shown that these expansions lead to systems of Fredholm integral equations. In Part II, the electric correlation function of the eight-vertex model for T < T/sub c/ is studied. The eight vertex model decouples to two independent Ising models when the four spin coupling vanishes. To first order in the four-spin coupling, the electric correlation function is related to a three-point function of the Ising model. This relation is systematically investigated and the full dispersion expansion (to first order in four-spin coupling) is obtained. The results is a new kind of structure which, unlike those of many solvable models, is apparently not expressible in terms of linear integral equations

Two-proton correlation functions in nuclear reactions

International Nuclear Information System (INIS)

Verde, G.

2001-01-01

Full text: Proton-proton correlation functions can be used to study the space-time characteristics of nuclear reactions. For very short-lived sources, the maximum value of the correlation at 20 MeV/c, due to the attractive nature of the S-wave phase shift, provides a unique measure of the size of the emitting source. For long-lived sources, the height of this maximum depends, in addition, on the life time of the source. In this talk, we investigate the common reaction scenario involving both fast dynamical as well as slower emissions from evaporation and/or secondary decays of heavy fragments. We show that the maximum at 20 MeV/c depends both on the source dimension and on the fraction of coincident proton pairs produced in the early stage of the reaction, dominated by fast dynamical preequilibrium emission. The width of the peak at 20 MeV/c, on the other hand, is uniquely correlated to the size of the source. Hence, the size of the emitting source must be extracted from the width or, even better, from the entire shape of the correlation peak, and not from the height. By numerically inverting the measured correlation function, we show that existing data determine only the shape of the fast dynamical source and that its size changes little with proton momenta, contrary to previous analyses with Gaussian sources of zero-lifetime. We further show that the well documented dramatic decrease in the correlation maximum with decreasing total proton momentum reflects directly a corresponding decrease in the fraction of contributing proton pairs from preequilibrium emissions. This provides a powerful method to decompose the proton spectrum into a fraction that originates from fast dynamical emission and a complimentary fraction that originates from slower evaporative emission or secondary decays. We discuss also the comparison of such correlations to transport theories and the generalizations of these techniques to correlations between composite particles. Such studies can

Factors affecting scent-marking behaviour in Eurasion beaver (Castor fiber)

NARCIS (Netherlands)

Rosell, F.; Nolet, B.A.

1997-01-01

We tested the hypothesis that a main function of territory marking in Eurasian beaver (Castor fiber) is defense of the territory. The results showed that: (1) beaver colonies with close neighbors scent-mark more often than isolated ones; (2) the number of scent markings increased significantly with

Development of Colle-Salvetti type electron-nucleus correlation functional for MC-DFT

Energy Technology Data Exchange (ETDEWEB)

Udagawa, Taro [Department of Chemistry and Biomolecuar Science, Faculty of Engineering, Gifu University, Yanagido 1-1, Gifu 501-1193 (Japan); Tsuneda, Takao [Fuel Cell Nanomaterials Center, University of Yamanashi, Miyamae-cho 6-43, Kofu 400-0021 (Japan); Tachikawa, Masanori [Quqnatum Chemistry Division, Graduate School of Science, Yokohama City University, Seto 22-2, Kanazawa, Yokohama 236-0027 (Japan)

2015-12-31

A Colle-Salvetti type electron-nucleus correlation functional for multicomponent density-functional theory is proposed. We demonstrate that our correlation functional quantitatively reproduces the quantum nuclear effects of protons; the mean absolute deviation value is 2.8 millihartrees for the optimized structure of hydrogen-containing molecules. We also show other practical calculations with our new electron-deuteron and electron-triton correlation functionals. Since this functional is derived without any unphysical assumption, the strategy taken in this development will be a promising recipe to make new functionals for the potentials of other particles’ interactions.

Demographic and Parenting Correlates of Adolescent Sleep Functioning

OpenAIRE

Zapata Roblyer, Martha I.; Grzywacz, Joseph. G.

2015-01-01

Despite the importance of parenting practices for adolescent adjustment, parenting correlates of adolescent sleep functioning remain understudied. This study delineated patterns of sleep functioning in a sample of ethnically diverse, low-income, adolescents and examined associations among three types of parenting practices (parental involvement, parent-child conflict, and parental control) and adolescent sleep functioning (difficulties initiating sleep and maintaining sleep, and sleep duratio...

Nonreciprocal Green’s function retrieval by cross correlation

NARCIS (Netherlands)

Wapenaar, C.P.A.

2006-01-01

The cross correlation of two recordings of a diffuse acoustic wave field at different receivers yields the Green’s function between these receivers. In nearly all cases considered so far the wave equation obeys time-reversal invariance and the Green’s function obeys source-receiver reciprocity. Here

A method for studying knife tool marks on bone.

Science.gov (United States)

Shaw, Kai-Ping; Chung, Ju-Hui; Chung, Fang-Chun; Tseng, Bo-Yuan; Pan, Chih-Hsin; Yang, Kai-Ting; Yang, Chun-Pang

2011-07-01

The characteristics of knife tool marks retained on hard tissues can be used to outline the shape and angle of a knife. The purpose of this study was to describe such marks on bone tissues that had been chopped with knives. A chopping stage with a gravity accelerator and a fixed bone platform was designed to reconstruct the chopping action. A digital microscope was also used to measure the knife angle (θ) and retained V-shape tool mark angle (ψ) in a pig skull. The κ value (elasticity coefficient; θ/ψ) was derived and recorded after the knife angle (θ) and the accompanied velocity were compared with the proportional impulsive force of the knife and ψ on the bone. The constant impulsive force revealed a correlation between the V-shape tool mark angle (ψ) and the elasticity coefficient (κ). These results describe the tool marks--crucial in the medicolegal investigation--of a knife on hard tissues. © 2011 American Academy of Forensic Sciences.

The statistics of galaxies: beyond correlation functions

International Nuclear Information System (INIS)

Lachieze-Rey, M.

1988-01-01

I mention some normalization problems encountered when estimating the 2-point correlation functions in samples of galaxies of different average densities. I present some aspects of the void probability function as a statistical indicator, free of such normalization problems. Finally I suggest a new statistical approach to give an account in a synthetic way of those aspects of the galaxy distribution that a conventional method is unable to characterize

Differential Signature of the Centrosomal MARK4 Isoforms in Glioma

Directory of Open Access Journals (Sweden)

Ivana Magnani

2011-01-01

Full Text Available Background: MAP/microtubule affinity-regulating kinase 4 (MARK4 is a serine-threonine kinase expressed in two spliced isoforms, MARK4L and MARK4S, of which MARK4L is a candidate for a role in neoplastic transformation. Methods: We performed mutation analysis to identify sequence alterations possibly affecting MARK4 expression. We then investigated the MARK4L and MARK4S expression profile in 21 glioma cell lines and 36 tissues of different malignancy grades, glioblastoma-derived cancer stem cells (GBM CSCs and mouse neural stem cells (NSCs by real-time PCR, immunoblotting and immunohistochemistry. We also analyzed the sub-cellular localisation of MARK4 isoforms in glioma and normal cell lines by immunofluorescence. Results: Mutation analysis rules out sequence variations as the cause of the altered MARK4 expression in glioma. Expression profiling confirms that MARK4L is the predominant isoform, whereas MARK4S levels are significantly decreased in comparison and show an inverse correlation with tumour grade. A high MARK4L/MARK4S ratio also characterizes undifferentiated cells, such as GBM CSCs and NSCs. Accordingly, only MARK4L is expressed in brain neurogenic regions. Moreover, while both MARK4 isoforms are localised to the centrosome and midbody in glioma and normal cells, the L isoform exhibits an additional nucleolar localisation in tumour cells. Conclusions: The observed switch towards MARK4L suggests that the balance between the MARK4 isoforms is carefully guarded during neural differentiation but may be subverted in gliomagenesis. Moreover, the MARK4L nucleolar localisation in tumour cells features this MARK4 isoform as a nucleolus-associated tumour marker.

Multiple soft limits of cosmological correlation functions

International Nuclear Information System (INIS)

Joyce, Austin; Khoury, Justin; Simonović, Marko

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 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

Structural and functional correlates of hypnotic depth and suggestibility.

Science.gov (United States)

McGeown, William Jonathan; Mazzoni, Giuliana; Vannucci, Manila; Venneri, Annalena

2015-02-28

This study explores whether self-reported depth of hypnosis and hypnotic suggestibility are associated with individual differences in neuroanatomy and/or levels of functional connectivity. Twenty-nine people varying in suggestibility were recruited and underwent structural, and after a hypnotic induction, functional magnetic resonance imaging at rest. We used voxel-based morphometry to assess the correlation of grey matter (GM) and white matter (WM) against the independent variables: depth of hypnosis, level of relaxation and hypnotic suggestibility. Functional networks identified with independent components analysis were regressed with the independent variables. Hypnotic depth ratings were positively correlated with GM volume in the frontal cortex and the anterior cingulate cortex (ACC). Hypnotic suggestibility was positively correlated with GM volume in the left temporal-occipital cortex. Relaxation ratings did not correlate significantly with GM volume and none of the independent variables correlated with regional WM volume measures. Self-reported deeper levels of hypnosis were associated with less connectivity within the anterior default mode network. Taken together, the results suggest that the greater GM volume in the medial frontal cortex and ACC, and lower connectivity in the DMN during hypnosis facilitate experiences of greater hypnotic depth. The patterns of results suggest that hypnotic depth and hypnotic suggestibility should not be considered synonyms. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Biologic variability and correlation of platelet function testing in healthy dogs.

Science.gov (United States)

Blois, Shauna L; Lang, Sean T; Wood, R Darren; Monteith, Gabrielle

2015-12-01

Platelet function tests are influenced by biologic variability, including inter-individual (CVG ) and intra-individual (CVI ), as well as analytic (CVA ) variability. Variability in canine platelet function testing is unknown, but if excessive, would make it difficult to interpret serial results. Additionally, the correlation between platelet function tests is poor in people, but not well described in dogs. The aims were to: (1) identify the effect of variation in preanalytic factors (venipuncture, elapsed time until analysis) on platelet function tests; (2) calculate analytic and biologic variability of adenosine diphosphate (ADP) and arachidonic acid (AA)-induced thromboelastograph platelet mapping (TEG-PM), ADP-, AA-, and collagen-induced whole blood platelet aggregometry (WBA), and collagen/ADP and collagen/epinephrine platelet function analysis (PFA-CADP, PFA-CEPI); and (3) determine the correlation between these variables. In this prospective observational trial, platelet function was measured once every 7 days, for 4 consecutive weeks, in 9 healthy dogs. In addition, CBC, TEG-PM, WBA, and PFA were performed. Overall coefficients of variability ranged from 13.3% to 87.8% for the platelet function tests. Biologic variability was highest for AA-induced maximum amplitude generated during TEG-PM (MAAA; CVG = 95.3%, CVI = 60.8%). Use of population-based reference intervals (RI) was determined appropriate only for PFA-CADP (index of individuality = 10.7). There was poor correlation between most platelet function tests. Use of population-based RI appears inappropriate for most platelet function tests, and tests poorly correlate with one another. Future studies on biologic variability and correlation of platelet function tests should be performed in dogs with platelet dysfunction and those treated with antiplatelet therapy. © 2015 American Society for Veterinary Clinical Pathology.

The time-oriented boundary states and the Lorentzian-spinfoam correlation functions

International Nuclear Information System (INIS)

Bianchi, Eugenio; Ding You

2012-01-01

A time-oriented semiclassical boundary state is introduced to calculate the correlation function in the Lorentzian Engle-Pereira-Rovelli-Livine spinfoam model. The resulting semiclassical correlation function is shown to match with the one in Regge calculus in a proper limit.

Accuracy of three-body wave functions obtained with the correlation-function hyperspherical-harmonic method

International Nuclear Information System (INIS)

Haftel, M.I.; Mandelzweig, V.B.

1990-01-01

The local convergence and accuracy of wave functions obtained by direct solution of the Schroedinger equation with the help of the correlation-function hyperspherical-harmonic method are analyzed for ground and excited states of the helium atom and for the ground state of the positronium negative ion. The inclusion of the cusp conditions into the correlation function is shown to be of crucial importance, not only near the coalescence points, but also away from them. The proper inclusion of all cusps yields for the ground state of the helium atom the local wave-function accuracy of about 10 -7 for different interparticle distances. The omission of one of the cusps in the excited helium atom reduces the wave-function precision to 10 -2 near the corresponding coalescence point and to 10 -4 --10 -5 away from it

Pulmonary function tests correlated with thoracic volumes in adolescent idiopathic scoliosis.

Science.gov (United States)

Ledonio, Charles Gerald T; Rosenstein, Benjamin E; Johnston, Charles E; Regelmann, Warren E; Nuckley, David J; Polly, David W

2017-01-01

Scoliosis deformity has been linked with deleterious changes in the thoracic cavity that affect pulmonary function. The causal relationship between spinal deformity and pulmonary function has yet to be fully defined. It has been hypothesized that deformity correction improves pulmonary function by restoring both respiratory muscle efficiency and increasing the space available to the lungs. This research aims to correlate pulmonary function and thoracic volume before and after scoliosis correction. Retrospective correlational analysis between thoracic volume modeling from plain x-rays and pulmonary function tests was conducted. Adolescent idiopathic scoliosis patients enrolled in a multicenter database were sorted by pre-operative Total Lung Capacities (TLC) % predicted values from their Pulmonary Function Tests (PFT). Ten patients with the best and ten patients with the worst TLC values were included. Modeled thoracic volume and TLC values were compared before and 2 years after surgery. Scoliosis correction resulted in an increase in the thoracic volume for patients with the worst initial TLCs (11.7%) and those with the best initial TLCs (12.5%). The adolescents with the most severe pulmonary restriction prior to surgery strongly correlated with post-operative change in total lung capacity and thoracic volume (r 2  = 0.839; p volume in this group was 373.1 cm 3 (11.7%) which correlated with a 21.2% improvement in TLC. Scoliosis correction in adolescents was found to increase thoracic volume and is strongly correlated with improved TLC in cases with severe restrictive pulmonary function, but no correlation was found in cases with normal pulmonary function. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:175-182, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Invariant mass dependence of two-pion inclusive correlation functions

International Nuclear Information System (INIS)

Berger, E.L.; Singer, R.; Thomas, G.H.; Kafka, T.

1976-06-01

High energy two-particle inclusive correlations are studied as a function of the invariant mass M of the pair. Using data from 205 GeV/c pp interactions, one compares the correlation functions C(M) for (+-) and (--) pairs of produced pions. Strong positive correlations are observed in both distributions in the form of a broad threshold enhancement at small M. The decrease of C(M) as M increases is interpreted in the Mueller-Regge framework. From the M dependence of C +- one extracts an effective trajectory intercept of roughly α(0) approximately equal to 0.5 +- 0.1, consistent with the (rho,f) pair. For the exotic (--) system, one finds a low intercept, α(0) approximately equal to -0.5. A rho resonance signal is observed above background in C +- (M). Near threshold, effects suggestive of Bose symmetry are seen but are not conclusive. In an exclusive picture, one relates most of the correlation in the threshold region to resonances involving three or more pions. One also examines the joint correlations in M and the azimuthal angle phi

Active control of residual tool marks for freeform optics functionalization by novel biaxial servo assisted fly cutting.

Science.gov (United States)

Zhu, Zhiwei; To, Suet; Zhang, Shaojian

2015-09-01

The inherent residual tool marks (RTM) with particular patterns highly affect optical functions of the generated freeform optics in fast tool servo or slow tool servo (FTS/STS) diamond turning. In the present study, a novel biaxial servo assisted fly cutting (BSFC) method is developed for flexible control of the RTM to be a functional micro/nanotexture in freeform optics generation, which is generally hard to achieve in FTS/STS diamond turning. In the BSFC system, biaxial servo motions along the z-axis and side-feeding directions are mainly adopted for primary surface generation and RTM control, respectively. Active control of the RTM from the two aspects, namely, undesired effect elimination or effective functionalization, are experimentally demonstrated by fabricating a typical F-theta freeform surface with scattering homogenization and two functional microstructures with imposition of secondary phase gratings integrating both reflective and diffractive functions.

On the zero temperature limit of the Kubo-transformed quantum time correlation function

Science.gov (United States)

Hernández de la Peña, Lisandro

2014-04-01

The zero temperature limit of several quantum time correlation functions is analysed. It is shown that while the canonical quantum time correlation function retains the full dynamical information as temperature approaches zero, the Kubo-transformed and the thermally symmetrised quantum time correlation functions lose all dynamical information at this limit. This is shown to be a consequence of the projection onto the ground state, via the limiting process of the quantities ? and ?, either together as a product, or separately. Although these findings would seem to suggest that finite-temperature methods commonly used to estimate Kubo correlation functions would be incapable of retaining any ground state dynamics, we propose a route for recovering in principle all dynamical information at the ground state. It is first shown that the usual frequency space relation between canonical and Kubo correlation functions also holds for microcanonical time correlation functions. Since the Kubo-transformed microcanonical correlation function can be obtained from the usual finite-temperature function by including a projection onto the corresponding microcanonical ensemble, finite-temperature methods, properly modified to incorporate such a constraint, can be used to capture full quantum dynamics at any arbitrary energy state, including the ground state. This approach is illustrated with the application of centroid dynamics to the ground state dynamics of the harmonic oscillator.

Decay of Complex-Time Determinantal and Pfaffian Correlation Functionals in Lattices

Science.gov (United States)

Aza, N. J. B.; Bru, J.-B.; de Siqueira Pedra, W.

2018-06-01

We supplement the determinantal and Pfaffian bounds of Sims and Warzel (Commun Math Phys 347:903-931, 2016) for many-body localization of quasi-free fermions, by considering the high dimensional case and complex-time correlations. Our proof uses the analyticity of correlation functions via the Hadamard three-line theorem. We show that the dynamical localization for the one-particle system yields the dynamical localization for the many-point fermionic correlation functions, with respect to the Hausdorff distance in the determinantal case. In Sims and Warzel (2016), a stronger notion of decay for many-particle configurations was used but only at dimension one and for real times. Considering determinantal and Pfaffian correlation functionals for complex times is important in the study of weakly interacting fermions.

Decay of Complex-Time Determinantal and Pfaffian Correlation Functionals in Lattices

Science.gov (United States)

Aza, N. J. B.; Bru, J.-B.; de Siqueira Pedra, W.

2018-04-01

We supplement the determinantal and Pfaffian bounds of Sims and Warzel (Commun Math Phys 347:903-931, 2016) for many-body localization of quasi-free fermions, by considering the high dimensional case and complex-time correlations. Our proof uses the analyticity of correlation functions via the Hadamard three-line theorem. We show that the dynamical localization for the one-particle system yields the dynamical localization for the many-point fermionic correlation functions, with respect to the Hausdorff distance in the determinantal case. In Sims and Warzel (2016), a stronger notion of decay for many-particle configurations was used but only at dimension one and for real times. Considering determinantal and Pfaffian correlation functionals for complex times is important in the study of weakly interacting fermions.

Nonperturbative renormalization-group approach preserving the momentum dependence of correlation functions

Science.gov (United States)

Rose, F.; Dupuis, N.

2018-05-01

We present an approximation scheme of the nonperturbative renormalization group that preserves the momentum dependence of correlation functions. This approximation scheme can be seen as a simple improvement of the local potential approximation (LPA) where the derivative terms in the effective action are promoted to arbitrary momentum-dependent functions. As in the LPA, the only field dependence comes from the effective potential, which allows us to solve the renormalization-group equations at a relatively modest numerical cost (as compared, e.g., to the Blaizot-Mendéz-Galain-Wschebor approximation scheme). As an application we consider the two-dimensional quantum O(N ) model at zero temperature. We discuss not only the two-point correlation function but also higher-order correlation functions such as the scalar susceptibility (which allows for an investigation of the "Higgs" amplitude mode) and the conductivity. In particular, we show how, using Padé approximants to perform the analytic continuation i ωn→ω +i 0+ of imaginary frequency correlation functions χ (i ωn) computed numerically from the renormalization-group equations, one can obtain spectral functions in the real-frequency domain.

Object marking in Swahili: Definiteness, specificity, or both ...

African Journals Online (AJOL)

This article examines the role of object marking in relation to definiteness and specificity in Swahili. Object marking in general has attracted the attention of many scholars in the field of Bantu linguistics due to the complex nature of object markers (OMs) and varying functions they fulfil in Bantu. Opinions differ on the role of ...

Correlations between Sportsmen’s Morpho-Functional Measurements and Voice Acoustic Variables

Directory of Open Access Journals (Sweden)

Rexhepi Agron M.

2016-12-01

Full Text Available Purpose. Since human voice characteristics are specific to each individual, numerous anthropological studies have been oriented to find significant relationships between voice and morpho-functional features. The goal of this study was to identify the correlation between seven morpho-functional variables and six voice acoustic parameters in sportsmen. Methods. Following the protocols of the International Biological Program, seven morpho-functional variables and six voice acoustic parameters have been measured in 88 male professional athletes from Kosovo, aged 17-35 years, during the period of April-October 2013. The statistical analysis was accomplished through the SPSS program, version 20. The obtained data were analysed through descriptive parameters and with Spearman’s method of correlation analysis. Results. Spearman’s method of correlation showed significant negative correlations (R = -0.215 to -0.613; p = 0.05 between three voice acoustic variables of the fundamental frequency of the voice sample (Mean, Minimum, and Maximum Pitch and six morpho-functional measures (Body Height, Body Weight, Margaria-Kalamen Power Test, Sargent Jump Test, Pull-up Test, and VO2max.abs. Conclusions. The significant correlations imply that the people with higher stature have longer vocal cords and a lower voice. These results encourage investigations on predicting sportsmen’s functional abilities on the basis of their voice acoustic parameters.

Finite-size effects on current correlation functions

Science.gov (United States)

Chen, Shunda; Zhang, Yong; Wang, Jiao; Zhao, Hong

2014-02-01

We study why the calculation of current correlation functions (CCFs) still suffers from finite-size effects even when the periodic boundary condition is taken. Two important one-dimensional, momentum-conserving systems are investigated as examples. Intriguingly, it is found that the state of a system recurs in the sense of microcanonical ensemble average, and such recurrence may result in oscillations in CCFs. Meanwhile, we find that the sound mode collisions induce an extra time decay in a current so that its correlation function decays faster (slower) in a smaller (larger) system. Based on these two unveiled mechanisms, a procedure for correctly evaluating the decay rate of a CCF is proposed, with which our analysis suggests that the global energy CCF decays as ˜t-2/3 in the diatomic hard-core gas model and in a manner close to ˜t-1/2 in the Fermi-Pasta-Ulam-β model.

Estimation of Correlation Functions by the Random Decrement Technique

DEFF Research Database (Denmark)

Brincker, Rune; Krenk, Steen; Jensen, Jakob Laigaard

responses simulated by two SDOF ARMA models loaded by the same bandlimited white noise. The speed and the accuracy of the RDD technique is compared to the Fast Fourier Transform (FFT) technique. The RDD technique does not involve multiplications, but only additions. Therefore, the technique is very fast......The Random Decrement (RDD) Technique is a versatile technique for characterization of random signals in the time domain. In this paper a short review of the theoretical basis is given, and the technique is illustrated by estimating auto-correlation functions and cross-correlation functions on modal...

Estimation of Correlation Functions by the Random Decrement Technique

DEFF Research Database (Denmark)

Brincker, Rune; Krenk, Steen; Jensen, Jacob Laigaard

1991-01-01

responses simulated by two SDOF ARMA models loaded by the same band-limited white noise. The speed and the accuracy of the RDD technique is compared to the Fast Fourier Transform (FFT) technique. The RDD technique does not involve multiplications, but only additions. Therefore, the technique is very fast......The Random Decrement (RDD) Technique is a versatile technique for characterization of random signals in the time domain. In this paper a short review of the theoretical basis is given, and the technique is illustrated by estimating auto-correlation functions and cross-correlation functions on modal...

Estimation of Correlation Functions by the Random Decrement Technique

DEFF Research Database (Denmark)

Brincker, Rune; Krenk, Steen; Jensen, Jakob Laigaard

1992-01-01

responses simulated by two SDOF ARMA models loaded by the same bandlimited white noise. The speed and the accuracy of the RDD technique is compared to the Fast Fourier Transform (FFT) technique. The RDD technique does not involve multiplications, but only additions. Therefore, the technique is very fast......The Random Decrement (RDD) Technique is a versatile technique for characterization of random signals in the time domain. In this paper a short review of the theoretical basis is given, and the technique is illustrated by estimating auto-correlation functions and cross-correlation functions on modal...

Correlation functions of the spin chains. Algebraic Bethe Ansatz approach

International Nuclear Information System (INIS)

Kitanine, N.

2007-09-01

Spin chains are the basic elements of integrable quantum models. These models have direct applications in condense matter theory, in statistical physics, in quantum optics, in field theory and even in string theory but they are also important because they enable us to solve, in an exact manner, non-perturbative phenomena that otherwise would stay unresolved. The method described in this work is based on the algebraic Bethe Ansatz. It is shown how this method can be used for the computation of null temperature correlation functions of the Heisenberg 1/2 spin chain. The important point of this approach is the solution of the inverse quantum problem given by the XXZ spin chain. This solution as well as a simple formulae for the scalar product of the Bethe states, have enabled us to get the most basic correlation functions under the form of multiple integrals. The formalism of multiple integrals open the way for asymptotic analysis for a few physical quantities like the probability of vacuum formation. It is worth noticing that this formalism can give exact results for two-point functions that are the most important correlation functions for applications. A relationship has been discovered between these multiple integrals and the sum of the form factors. The results have been extended to dynamical correlation functions. (A.C.)

Correlation function behavior in quantum systems which are classically chaotic

International Nuclear Information System (INIS)

Berman, G.P.; Kolovsky, A.R.

1983-01-01

The time behavior of a phase correlation function for dynamical quantum systems which are classically chaotic is considered. It is shown that under certain conditions there are three time regions of the quantum correlations behavior; the region of classical stochasticity (exponential decay of quantum correlations); the region of the correlations decay with a power law; the region of the constant level of the quantum correlations. The boundaries of these time regions are presented. The estimation of a remaining level of the quantum correlations is given. (orig.)

Exponential Correlation of IQ and the Wealth of Nations

Science.gov (United States)

Dickerson, Richard E.

2006-01-01

Plots of mean IQ and per capita real Gross Domestic Product for groups of 81 and 185 nations, as collected by Lynn and Vanhanen, are best fitted by an exponential function of the form: GDP = "a" * 10["b"*(IQ)], where "a" and "b" are empirical constants. Exponential fitting yields markedly higher correlation coefficients than either linear or…

The correlation functions for the clustering of galaxies and Abell clusters

International Nuclear Information System (INIS)

Jones, B.J.T.; Jones, J.E.; Copenhagen Univ.

1985-01-01

The difference in amplitudes between the galaxy-galaxy correlation function and the correlation function between Abell clusters is a consequence of two facts. Firstly, most Abell clusters with z<0.08 lie in a relatively small volume of the sampled space, and secondly, the fraction of galaxies lying in Abell clusters differs considerably inside and outside of this volume. (The Abell clusters are confined to a smaller volume of space than are the galaxies.) We discuss the implications of this interpretation of the clustering correlation functions and present a simple model showing how such a situation may arise quite naturally in standard theories for galaxy formation. (orig.)

Density-correlation functions in Calogero-Sutherland models

International Nuclear Information System (INIS)

Minahan, J.A.; Polychronakos, A.P.

1994-01-01

Using arguments from two-dimensional Yang-Mills theory and the collective coordinate formulation of the Calogero-Sutherland model, we conjecture the dynamical density-correlation function for coupling l and 1/l, where l is an integer. We present overwhelming evidence that the conjecture is indeed correct

Density correlation functions in Calogero-Sutherland models

CERN Document Server

Minahan, Joseph A.; Joseph A Minahan; Alexios P Polychronakos

1994-01-01

Using arguments from two dimensional Yang-Mills theory and the collective coordinate formulation of the Calogero-Sutherland model, we conjecture the dynamical density correlation function for coupling l and 1/l, where l is an integer. We present overwhelming evidence that the conjecture is indeed correct.

Correlation function of weakly interacting bosons in a disordered lattice

Energy Technology Data Exchange (ETDEWEB)

Deissler, B; Lucioni, E; Modugno, M; Roati, G; Tanzi, L; Zaccanti, M; Inguscio, M; Modugno, G, E-mail: deissler@lens.unifi.it, E-mail: modugno@lens.unifi.it [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, 50019 Sesto Fiorentino (Italy)

2011-02-15

One of the most important issues in disordered systems is the interplay of the disorder and repulsive interactions. Several recent experimental advances on this topic have been made with ultracold atoms, in particular the observation of Anderson localization and the realization of the disordered Bose-Hubbard model. There are, however, still questions as to how to differentiate the complex insulating phases resulting from this interplay, and how to measure the size of the superfluid fragments that these phases entail. It has been suggested that the correlation function of such a system can give new insights, but so far very little experimental investigation has been performed. Here, we show the first experimental analysis of the correlation function for a weakly interacting, bosonic system in a quasiperiodic lattice. We observe an increase in the correlation length as well as a change in the shape of the correlation function in the delocalization crossover from Anderson glass to coherent, extended state. In between, the experiment indicates the formation of progressively larger coherent fragments, consistent with a fragmented BEC, or Bose glass.

Correlation function of weakly interacting bosons in a disordered lattice

International Nuclear Information System (INIS)

Deissler, B; Lucioni, E; Modugno, M; Roati, G; Tanzi, L; Zaccanti, M; Inguscio, M; Modugno, G

2011-01-01

One of the most important issues in disordered systems is the interplay of the disorder and repulsive interactions. Several recent experimental advances on this topic have been made with ultracold atoms, in particular the observation of Anderson localization and the realization of the disordered Bose-Hubbard model. There are, however, still questions as to how to differentiate the complex insulating phases resulting from this interplay, and how to measure the size of the superfluid fragments that these phases entail. It has been suggested that the correlation function of such a system can give new insights, but so far very little experimental investigation has been performed. Here, we show the first experimental analysis of the correlation function for a weakly interacting, bosonic system in a quasiperiodic lattice. We observe an increase in the correlation length as well as a change in the shape of the correlation function in the delocalization crossover from Anderson glass to coherent, extended state. In between, the experiment indicates the formation of progressively larger coherent fragments, consistent with a fragmented BEC, or Bose glass.

One-loop correlation functions in the model of noncritical fermionic strings

International Nuclear Information System (INIS)

Belokurov, V.V.; Iofa, M.Z.

1996-01-01

In the model of noncritical fermionic strings, the David-Distler-Kawai ansatz is used to study one-loop n-point (n≤4) correlation functions for the vertex operators of massless bosonic states. The action functional of the model is the sum of super-Liouville action functional for the conformal mode and the action functional of d scalar supermultiplets. It is assumed that the total cosmological term is equal to zero. The amplitudes are calculated as the residues at the pole of the correlation function that corresponds to the conservation of Liouville momentum in the form Σβi=Q(1-h), where Q=√(9-d)/2 and h is the genus of the work sheet. In the one-loop approximation, the amplitudes can be obtained in the modular-invariant form, provided that the coefficients appearing in the sum over spin structures depend on moduli. In this case, the modular measure is defined up to a modular-invariant factor. This arbitrariness can be used to represent one-point correlation functions in the same functional form as for strings of critical dimension

Microscopic universality of complex matrix model correlation functions at weak non-Hermiticity

International Nuclear Information System (INIS)

Akemann, G.

2002-01-01

The microscopic correlation functions of non-chiral random matrix models with complex eigenvalues are analyzed for a wide class of non-Gaussian measures. In the large-N limit of weak non-Hermiticity, where N is the size of the complex matrices, we can prove that all k-point correlation functions including an arbitrary number of Dirac mass terms are universal close to the origin. To this aim we establish the universality of the asymptotics of orthogonal polynomials in the complex plane. The universality of the correlation functions then follows from that of the kernel of orthogonal polynomials and a mapping of massive to massless correlators

Reduced density-matrix functional theory: Correlation and spectroscopy.

Science.gov (United States)

Di Sabatino, S; Berger, J A; Reining, L; Romaniello, P

2015-07-14

In this work, we explore the performance of approximations to electron correlation in reduced density-matrix functional theory (RDMFT) and of approximations to the observables calculated within this theory. Our analysis focuses on the calculation of total energies, occupation numbers, removal/addition energies, and spectral functions. We use the exactly solvable Hubbard dimer at 1/4 and 1/2 fillings as test systems. This allows us to analyze the underlying physics and to elucidate the origin of the observed trends. For comparison, we also report the results of the GW approximation, where the self-energy functional is approximated, but no further hypothesis is made concerning the approximations of the observables. In particular, we focus on the atomic limit, where the two sites of the dimer are pulled apart and electrons localize on either site with equal probability, unless a small perturbation is present: this is the regime of strong electron correlation. In this limit, using the Hubbard dimer at 1/2 filling with or without a spin-symmetry-broken ground state allows us to explore how degeneracies and spin-symmetry breaking are treated in RDMFT. We find that, within the used approximations, neither in RDMFT nor in GW, the signature of strong correlation is present, when looking at the removal/addition energies and spectral function from the spin-singlet ground state, whereas both give the exact result for the spin-symmetry broken case. Moreover, we show how the spectroscopic properties change from one spin structure to the other.

Funciones psíquicas de las marcas corporales. // Psychic functions of body marking.

Directory of Open Access Journals (Sweden)

Margarita María Valencia Valencia.

2010-06-01

Full Text Available This article shows the results of a research titled Funciones psíquicas de las marcas corporales (Psychic Functions of Body Marking that analyses the tattoo, scarification and piercing boom in teenagers and young people. Its aim is to elucidate the body statute in our days. From the acknowledgment of the changes in status of human body throughout history and in different cultures, we investigate the special psychic functions of those practices and their symbolic implications, by using some psychoanalytical theories about body image and adolescence. // Este artículo presenta los resultados de la investigación Funciones psíquicas de las marcas corporales, que interroga el significado del auge de tatuajes, escarificaciones y piercings en adolescentes y jóvenes, con el fin de esclarecer el estatuto del cuerpo en la contemporaneidad. A partir de un reconocimiento de los cambios de estatus que el cuerpo ha tenido a través de la historia y las culturas, se indaga, con ayuda de las teorizaciones psicoanalíticas sobre lo corporal y la adolescencia, acerca de las funciones psíquicas particulares de dichas prácticas y su alcance simbolizador.

Source-Free Exchange-Correlation Magnetic Fields in Density Functional Theory.

Science.gov (United States)

Sharma, S; Gross, E K U; Sanna, A; Dewhurst, J K

2018-03-13

Spin-dependent exchange-correlation energy functionals in use today depend on the charge density and the magnetization density: E xc [ρ, m]. However, it is also correct to define the functional in terms of the curl of m for physical external fields: E xc [ρ,∇ × m]. The exchange-correlation magnetic field, B xc , then becomes source-free. We study this variation of the theory by uniquely removing the source term from local and generalized gradient approximations to the functional. By doing so, the total Kohn-Sham moments are improved for a wide range of materials for both functionals. Significantly, the moments for the pnictides are now in good agreement with experiment. This source-free method is simple to implement in all existing density functional theory codes.

Vacuum correlation functions for ghost superfields and multiloop amplitudes in the theory of closed superstrings

International Nuclear Information System (INIS)

Danilov, G.S.

1995-01-01

A new formalism for ghosts on complex (1 bar 1) supermanifolds of genus n > 1 is discussed in superstring theory. In this formalism, vacuum correlation functions for ghost superfields differ substantially from correlation functions discussed earlier. In particular, the new correlation functions do not have unphysical poles. Among other things, these correlation functions take into account contributions to partition functions from the phase space of modular forms and from zero modes of ghosts. The above correlation functions, obtained for all even spinor structures, can be used to evaluate partition functions from equations that are nothing but Ward identities. 21 refs

Correlation between special brain area and blood perfusion in patients with cerebral infarction at convalescent period Feasibility for quantitative determination and estimation of learning and memory function

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

BACKGROUND: Presently, clinic memory scale is used to evaluate learning memory ability in most studies,and the influence of difference in measurement condition of individuals exists.OBJECTIVE: To study the correlation between regional cerebral blood flow (rCBF) perfusion and learning memory function in special brain regions of patients with cerebral infarction at convalescent period,and to try to find out a method which can quantitatively evaluate learning ability.DESIGN: Case observation, and correlation analysis.SETTINGS: Shandong Institute for Behavioral Medicine; the Affiliated Hospital of Jining Medical College.PARTICIPANTS: Totally 70 patients with cerebral infarction admitted to Departtment of Neurology, Jining Medical College between January 2004 and December 2005 were involved. The involved patients, 58 male and 12 female, were averaged (52±3) years, and they were all right handed. They all met the diagnosis criteria instituted by the Fourth National Conference on Cerebrovascular Disease, and were confirmed as cerebral infarction by skull CT or MRI. Informed consents of detected items were obtained from all the patients and relatives.METHODS: When the patients were at convalescent period, their learning and memory ability were measured with" clinic memory scale (set A)". The 18 patients whose total mark over 100 were regarded as good learning memory function group; The 23 cases whose total mark less than 70 were regarded as poor learning memory function group. RCBF of hippocampus, nucleus amygdalae, temporal cortex and prefrontal lobe of patients between two groups were measured and compared by single photon emission computed tomography (SPECT). The total scores of the 18 good learning memory patients and 23 poor learning memory patients were taken as dependent variable Y, and their rCBFs of hippocampus, nucleus amygdale,temporal cortex and prefrontal lobe respectively as independent variable X for linear correlation analysis.MAIN OUTCOME MEASURES

PyCCF: Python Cross Correlation Function for reverberation mapping studies

Science.gov (United States)

Sun, Mouyuan; Grier, C. J.; Peterson, B. M.

2018-05-01

PyCCF emulates a Fortran program written by B. Peterson for use with reverberation mapping. The code cross correlates two light curves that are unevenly sampled using linear interpolation and measures the peak and centroid of the cross-correlation function. In addition, it is possible to run Monto Carlo iterations using flux randomization and random subset selection (RSS) to produce cross-correlation centroid distributions to estimate the uncertainties in the cross correlation results.

Structure functions and pair correlations of the quark-gluon plasma

International Nuclear Information System (INIS)

Thoma, Markus H.

2005-01-01

Recent experiments at RHIC and theoretical considerations indicate that the quark-gluon plasma, present in the fireball of relativistic heavy-ion collisions, might be in a liquid phase. The liquid state can be identified by characteristic correlation and structure functions. Here definitions of the structure functions and pair correlations of the quark-gluon plasma are presented as well as perturbative results. These definitions might be useful for verifying the quark-gluon-plasma liquid in QCD lattice calculations

The singular multiparticle correlation function and the α-model

International Nuclear Information System (INIS)

Bozek, P.; Ploszajczak, M.

1991-01-01

The comparison is made between the two descriptions of multiparticle correlations using either the α-model or the scale-invariant distribution functions. The case of the strong and weak intermittency is discussed. These two descriptions show similar results for both the scaled factorial moments and the scaled factorial correlators. It is shown that the dimensional projection does not alter this similarity and moreover, it explains an experimentally observed difference between the slopes of factorial moments and factorial correlators. (author) 8 refs.; 3 figs

Functional representation for the grand partition function of a multicomponent system of charged particles: Correlation functions of the reference system

Directory of Open Access Journals (Sweden)

O.V.Patsahan

2006-01-01

Full Text Available Based on the method of collective variables (CV with a reference system, the exact expression for the functional of the grand partition function of a m-component ionic model with charge and size asymmetry is found. Particular attention is paid to the n-th particle correlation functions of the reference system which is presented as a m-component system of "colour" hard spheres of the same diameter. A two-component model is considered in more detail. In this case the recurrence formulas for the correlation functions are found. A general case of a m-component inhomogeneous system of the "colour" hard spheres is also analysed.

Enamel-based mark performance for marking Chinese mystery snail Bellamya chinensis

Science.gov (United States)

Wong, Alec; Allen, Craig R.; Hart, Noelle M.; Haak, Danielle M.; Pope, Kevin L.; Smeenk, Nicholas A.; Stephen, Bruce J.; Uden, Daniel R.

2013-01-01

The exoskeleton of gastropods provides a convenient surface for carrying marks, and i the interest of improving future marking methods our laboratory assessed the performance of an enamel paint. The endurance of the paint was also compared to other marking methods assessed in the past. We marked the shells of 30 adult Chinese mystery snails Bellamya chinensis and held them in an aquarium for 181 days. We observed no complete degradation of any enamel-paint mark during the 181 days. The enamel-paint mark was superior to a nai;-polish mark, which lasted a median of 100 days. Enamel-paint marks also have a lower rate of loss (0.00 month-1 181 days) than plastic bee tags (0.01 month-1, 57 days), gouache paint (0.07 month-1, 18.5 days), or car body paint from studies found in scientific literature. Legibility of enamel-paint marks had a median lifetime of 102 days. The use of enamel paint on the shells of gastropods is a viable option for studies lasting up to 6 months. Furthermore, visits to capture-mark-recapture site 1 year after application of enamel-paint marks on B. chinesnis shells produced several individuals on which the enamel paint was still visible, although further testing is required to clarify durability over longer periods.

New angles on energy correlation functions

Energy Technology Data Exchange (ETDEWEB)

Moult, Ian [Berkeley Center for Theoretical Physics, University of California,Berkeley, CA 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory,Berkeley, CA 94720 (United States); Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States); Necib, Lina; Thaler, Jesse [Center for Theoretical Physics, Massachusetts Institute of Technology,Cambridge, MA 02139 (United States)

2016-12-29

Jet substructure observables, designed to identify specific features within jets, play an essential role at the Large Hadron Collider (LHC), both for searching for signals beyond the Standard Model and for testing QCD in extreme phase space regions. In this paper, we systematically study the structure of infrared and collinear safe substructure observables, defining a generalization of the energy correlation functions to probe n-particle correlations within a jet. These generalized correlators provide a flexible basis for constructing new substructure observables optimized for specific purposes. Focusing on three major targets of the jet substructure community — boosted top tagging, boosted W/Z/H tagging, and quark/gluon discrimination — we use power-counting techniques to identify three new series of powerful discriminants: M{sub i}, N{sub i}, and U{sub i}. The M{sub i} series is designed for use on groomed jets, providing a novel example of observables with improved discrimination power after the removal of soft radiation. The N{sub i} series behave parametrically like the N-subjettiness ratio observables, but are defined without respect to subjet axes, exhibiting improved behavior in the unresolved limit. Finally, the U{sub i} series improves quark/gluon discrimination by using higher-point correlators to simultaneously probe multiple emissions within a jet. Taken together, these observables broaden the scope for jet substructure studies at the LHC.

New angles on energy correlation functions

Science.gov (United States)

Moult, Ian; Necib, Lina; Thaler, Jesse

2016-12-01

Jet substructure observables, designed to identify specific features within jets, play an essential role at the Large Hadron Collider (LHC), both for searching for signals beyond the Standard Model and for testing QCD in extreme phase space regions. In this paper, we systematically study the structure of infrared and collinear safe substructure observables, defining a generalization of the energy correlation functions to probe n-particle correlations within a jet. These generalized correlators provide a flexible basis for constructing new substructure observables optimized for specific purposes. Focusing on three major targets of the jet substructure community — boosted top tagging, boosted W/Z/H tagging, and quark/gluon discrimination — we use power-counting techniques to identify three new series of powerful discriminants: M i , N i , and U i . The M i series is designed for use on groomed jets, providing a novel example of observables with improved discrimination power after the removal of soft radiation. The N i series behave parametrically like the N -subjettiness ratio observables, but are defined without respect to subjet axes, exhibiting improved behavior in the unresolved limit. Finally, the U i series improves quark/gluon discrimination by using higher-point correlators to simultaneously probe multiple emissions within a jet. Taken together, these observables broaden the scope for jet substructure studies at the LHC.

Air trapping in sarcoidosis on computed tomography: Correlation with lung function

International Nuclear Information System (INIS)

Davies, C.W.H.; Tasker, A.D.; Padley, S.P.G.; Davies, R.J.O.; Gleeson, F.V.

2000-01-01

AIMS: To document the presence and extent of air trapping on high resolution computed tomography (HRCT) in patients with pulmonary sarcoidosis and correlate HRCT features with pulmonary function tests. METHODS: Twenty-one patients with pulmonary sarcoidosis underwent HRCT and pulmonary function assessment at presentation. Inspiratory and expiratory HRCT were assessed for the presence and extent of air trapping, ground-glass opacification, nodularity, septal thickening, bronchiectasis and parenchymal distortion. HRCT features were correlated with pulmonary function tests. RESULTS: Air trapping on expiratory HRCT was present in 20/21 (95%) patients. The extent of air trapping correlated with percentage predicted residual volume (RV)/total lung capacity (TLC) (r = 0.499;P < 0.05) and percentage predicted maximal mid-expiratory flow rate between 25 and 75% of the vital capacity (r = -0.54;P < 0.05). Ground-glass opacification was present in four of 21 (19%), nodularity in 18/21 (86%), septal thickening in 18/21 (86%), traction bronchiectasis in 14/21 (67%) and distortion in 12/21 (57%) of patients; there were no significant relationships between these CT features and pulmonary function results. CONCLUSION: Air trapping is a common feature in sarcoidosis and correlates with evidence of small airways disease on pulmonary function testing. Davies, C.W.H. (2000). Clinical Radiology 55, 217-221

The sewing technique and correlation functions on arbitrary Riemann surfaces

International Nuclear Information System (INIS)

Di Vecchia, P.

1989-01-01

We describe in the case of free bosonic and fermionic theories the sewing procedure, that is a very convenient way for constructing correlation functions of these theories on an arbitrary Riemann surface from their knowledge on the sphere. The fundamental object that results from this construction is the N-point g-loop vertex. It summarizes the information of all correlation functions of the theory on an arbitrary Riemann surface. We then check explicitly the bosonization rules and derive some useful formulas. (orig.)

Total and Direct Correlation Function Integrals from Molecular Simulation of Binary Systems

DEFF Research Database (Denmark)

Wedberg, Nils Hejle Rasmus Ingemar; O’Connell, John P.; Peters, Günther H.J.

2011-01-01

The possibility for obtaining derivative properties for mixtures from integrals of spatial total and direct correlation functions obtained from molecular dynamics simulations is explored. Theoretically well-supported methods are examined to extend simulation radial distribution functions to long...... are consistent with an excess Helmholtz energy model fitted to available simulations. In addition, simulations of water/methanol and water/t-butanol mixtures have been carried out. The method yields results for partial molar volumes, activity coefficient derivatives, and individual correlation function integrals...... in reasonable agreement with smoothed experimental data. The proposed method for obtaining correlation function integrals is shown to perform at least as well as or better than two previously published approaches....

The ion-electron correlation function in liquid metals

International Nuclear Information System (INIS)

Takeda, S.; Tamaki, S.; Waseda, Y.

1985-01-01

The structure factors of liquid Zn at 723 K, Sn at 523 K and Bi at 573 K have been determined by neutron diffraction with sufficient accuracy and compared with those of X-ray diffraction. A remarkable difference in the structural information between the two methods is clearly found around the first peak region as well as in the slightly varied peak positions, and it is apparently larger than the experimental errors. With these facts in mind, a new method evaluating the ion-electron correlation function in liquid metals has been proposed by using the measured structural data of X-rays and neutrons, with the help of theoretical values of the electron-electron correlation function by he Utsumi-Ichimaru scheme. This method has been applied to liquid Zn, Sn and Bi, and the radial distribution function of valence electrons around an ion has been estimated, from which the ionic radius and the schematic diagram of the electron distribution map are obtained. The ionic radii evaluated in this work have been found to agree well with those proposed by Pauling. (author)

Exact ground-state correlation functions of one-dimenisonal strongly correlated electron models with resonating-valence-bond ground state

International Nuclear Information System (INIS)

Yamanaka, Masanori; Honjo, Shinsuke; Kohmoto, Mahito

1996-01-01

We investigate one-dimensional strongly correlated electron models which have the resonating-valence-bond state as the exact ground state. The correlation functions are evaluated exactly using the transfer matrix method for the geometric representations of the valence-bond states. In this method, we only treat matrices with small dimensions. This enables us to give analytical results. It is shown that the correlation functions decay exponentially with distance. The result suggests that there is a finite excitation gap, and that the ground state is insulating. Since the corresponding noninteracting systems may be insulating or metallic, we can say that the gap originates from strong correlation. The persistent currents of the present models are also investigated and found to be exactly vanishing

Influence of super-horizon modes on correlation functions during inflation

Science.gov (United States)

Deutsch, Anne-Sylvie

2018-05-01

Coupling between sub- and super-Hubble modes can affect the locally observed statistics of our universe. In the context of Quasi-Single Field Inflation, we can compute correlation functions and derive the influence of those unobservable modes on observed correlation functions as well as on the inferred cosmological parameters. We study how different classes of diagrams affect the bispectrum in the squeezed limit; in particular, while contact-like diagrams leave the scaling between the long and short modes unchanged, exchange-like diagrams do modify the shape of the bispectrum. We show that the mass of the hidden sector field can hence be biased by an unavoidable cosmic variance that can reach a 1-σ uncertainty of Script O(10%) for a weakly non-Gaussian universe. Finally, we go beyond the bispectrum and show how couplings between unobservable and observable modes can affect generic correlation functions with arbitrary order non-derivative self-interactions.

Correlation function analysis of the COBE differential microwave radiometer sky maps

Energy Technology Data Exchange (ETDEWEB)

Lineweaver, Charles Howe [Univ. of California, Berkeley, CA (United States). Space Sciences Lab.

1994-08-01

The Differential Microwave Radiometer (DMR) aboard the COBE satellite has detected anisotropies in the cosmic microwave background (CMB) radiation. A two-point correlation function analysis which helped lead to this discovery is presented in detail. The results of a correlation function analysis of the two year DMR data set is presented. The first and second year data sets are compared and found to be reasonably consistent. The positive correlation for separation angles less than ~20° is robust to Galactic latitude cuts and is very stable from year to year. The Galactic latitude cut independence of the correlation function is strong evidence that the signal is not Galactic in origin. The statistical significance of the structure seen in the correlation function of the first, second and two year maps is respectively > 9σ, > 10σ and > 18σ above the noise. The noise in the DMR sky maps is correlated at a low level. The structure of the pixel temperature covariance matrix is given. The noise covariance matrix of a DMR sky map is diagonal to an accuracy of better than 1%. For a given sky pixel, the dominant noise covariance occurs with the ring of pixels at an angular separation of 60° due to the 60° separation of the DMR horns. The mean covariance of 60° is 0.45%$+0.18\\atop{-0.14}$ of the mean variance. The noise properties of the DMR maps are thus well approximated by the noise properties of maps made by a single-beam experiment. Previously published DMR results are not significantly affected by correlated noise.

Assessment of density-functional approximations: Long-range correlations and self-interaction effects

International Nuclear Information System (INIS)

Jung, J.; Alvarellos, J.E.; Garcia-Gonzalez, P.; Godby, R.W.

2004-01-01

The complex nature of electron-electron correlations is made manifest in the very simple but nontrivial problem of two electrons confined within a sphere. The description of highly nonlocal correlation and self-interaction effects by widely used local and semilocal exchange-correlation energy density functionals is shown to be unsatisfactory in most cases. Even the best such functionals exhibit significant errors in the Kohn-Sham potentials and density profiles

Signed zeros of Gaussian vector fields - density, correlation functions and curvature

CERN Document Server

Foltin, G

2003-01-01

We calculate correlation functions of the (signed) density of zeros of Gaussian distributed vector fields. We are able to express correlation functions of arbitrary order through the curvature tensor of a certain abstract Riemann Cartan or Riemannian manifold. As an application, we discuss one- and two-point functions. The zeros of a two-dimensional Gaussian vector field model the distribution of topological defects in the high-temperature phase of two-dimensional systems with orientational degrees of freedom, such as superfluid films, thin superconductors and liquid crystals.

Decay of random correlation functions for unimodal maps

Science.gov (United States)

Baladi, Viviane; Benedicks, Michael; Maume-Deschamps, Véronique

2000-10-01

Since the pioneering results of Jakobson and subsequent work by Benedicks-Carleson and others, it is known that quadratic maps tfa( χ) = a - χ2 admit a unique absolutely continuous invariant measure for a positive measure set of parameters a. For topologically mixing tfa, Young and Keller-Nowicki independently proved exponential decay of correlation functions for this a.c.i.m. and smooth observables. We consider random compositions of small perturbations tf + ωt, with tf = tfa or another unimodal map satisfying certain nonuniform hyperbolicity axioms, and ωt chosen independently and identically in [-ɛ, ɛ]. Baladi-Viana showed exponential mixing of the associated Markov chain, i.e., averaging over all random itineraries. We obtain stretched exponential bounds for the random correlation functions of Lipschitz observables for the sample measure μωof almost every itinerary.

Linguistic constraints on children's overt marking of BE by dialect and age.

Science.gov (United States)

Roy, Joseph; Oetting, Janna B; Moland, Christy Wynn

2013-06-01

Overt marking of BE in nonmainstream adult dialects of English is influenced by a number of linguistic constraints, including the structure's person, number, tense, contractibility, and grammatical function. In the current study, the authors examined the effects of these constraints on overt marking of BE in children as a function of their nonmainstream English dialect and age. The data were language samples from 62 children, ages 4-6 years; 24 children spoke African American English (AAE), and 38 spoke Southern White English (SWE). Analyses included analysis of variance and logistic regression. Rates of overt marking varied by the children's dialect but not their age. Although the person, number, tense, and grammatical function of BE influenced the children's rates of marking, the nature and magnitude of the influence differed by the children's dialect. For AAE-speaking children, contractibility also influenced their marking of BE. Consistent with the adult literature, the current study showed that AAE- and SWE-speaking children marked BE in ways that differed from each other and from what has been documented for child speakers of Mainstream American English. These findings show stability in the use of BE in AAE and SWE that spans different generations and different dialect communities.

Four-point correlation function of stress-energy tensors in N=4 superconformal theories

CERN Document Server

Korchemsky, G P

2015-01-01

We derive the explicit expression for the four-point correlation function of stress-energy tensors in four-dimensional N=4 superconformal theory. We show that it has a remarkably simple and suggestive form allowing us to predict a large class of four-point correlation functions involving the stress-energy tensor and other conserved currents. We then apply the obtained results on the correlation functions to computing the energy-energy correlations, which measure the flow of energy in the final states created from the vacuum by a source. We demonstrate that they are given by a universal function independent of the choice of the source. Our analysis relies only on N=4 superconformal symmetry and does not use the dynamics of the theory.

Correlates of cognitive function scores in elderly outpatients.

Science.gov (United States)

Mangione, C M; Seddon, J M; Cook, E F; Krug, J H; Sahagian, C R; Campion, E W; Glynn, R J

1993-05-01

To determine medical, ophthalmologic, and demographic predictors of cognitive function scores as measured by the Telephone Interview for Cognitive Status (TICS), an adaptation of the Folstein Mini-Mental Status Exam. A secondary objective was to perform an item-by-item analysis of the TICS scores to determine which items correlated most highly with the overall scores. Cross-sectional cohort study. The Glaucoma Consultation Service of the Massachusetts Eye and Ear Infirmary. 472 of 565 consecutive patients age 65 and older who were seen at the Glaucoma Consultation Service between November 1, 1987 and October 31, 1988. Each subject had a standard visual examination and review of medical history at entry, followed by a telephone interview that collected information on demographic characteristics, cognitive status, health status, accidents, falls, symptoms of depression, and alcohol intake. A multivariate linear regression model of correlates of TICS score found the strongest correlates to be education, age, occupation, and the presence of depressive symptoms. The only significant ocular condition that correlated with lower TICS score was the presence of surgical aphakia (model R2 = .46). Forty-six percent (216/472) of patients fell below the established definition of normal on the mental status scale. In a logistic regression analysis, the strongest correlates of an abnormal cognitive function score were age, diabetes, educational status, and occupational status. An item analysis using step-wise linear regression showed that 85 percent of the variance in the TICS score was explained by the ability to perform serial sevens and to repeat 10 items immediately after hearing them. Educational status correlated most highly with both of these items (Kendall Tau R = .43 and Kendall Tau R = .30, respectively). Education, occupation, depression, and age were the strongest correlates of the score on this new screening test for assessing cognitive status. These factors were

Adaptive endpoint detection of seismic signal based on auto-correlated function

International Nuclear Information System (INIS)

Fan Wanchun; Shi Ren

2001-01-01

Based on the analysis of auto-correlation function, the notion of the distance between auto-correlation function was quoted, and the characterization of the noise and the signal with noise were discussed by using the distance. Then, the method of auto- adaptable endpoint detection of seismic signal based on auto-correlated similarity was summed up. The steps of implementation and determining of the thresholds were presented in detail. The experimental results that were compared with the methods based on artificial detecting show that this method has higher sensitivity even in a low signal with noise ratio circumstance

Nonlinearity of the forward-backward correlation function in the model with string fusion

Science.gov (United States)

Vechernin, Vladimir

2017-12-01

The behavior of the forward-backward correlation functions and the corresponding correlation coefficients between multiplicities and transverse momenta of particles produced in high energy hadronic interactions is analyzed by analytical and MC calculations in the models with and without string fusion. The string fusion is taking into account in simplified form by introducing the lattice in the transverse plane. The results obtained with two alternative definitions of the forward-backward correlation coefficient are compared. It is shown that the nonlinearity of correlation functions increases with the width of observation windows, leading at small string density to a strong dependence of correlation coefficient value on the definition. The results of the modeling enable qualitatively to explain the experimentally observed features in the behavior of the correlation functions between multiplicities and mean transverse momenta at small and large multiplicities.

Exchange-Correlation Effects for Noncovalent Interactions in Density Functional Theory.

Science.gov (United States)

Otero-de-la-Roza, A; DiLabio, Gino A; Johnson, Erin R

2016-07-12

In this article, we develop an understanding of how errors from exchange-correlation functionals affect the modeling of noncovalent interactions in dispersion-corrected density-functional theory. Computed CCSD(T) reference binding energies for a collection of small-molecule clusters are decomposed via a molecular many-body expansion and are used to benchmark density-functional approximations, including the effect of semilocal approximation, exact-exchange admixture, and range separation. Three sources of error are identified. Repulsion error arises from the choice of semilocal functional approximation. This error affects intermolecular repulsions and is present in all n-body exchange-repulsion energies with a sign that alternates with the order n of the interaction. Delocalization error is independent of the choice of semilocal functional but does depend on the exact exchange fraction. Delocalization error misrepresents the induction energies, leading to overbinding in all induction n-body terms, and underestimates the electrostatic contribution to the 2-body energies. Deformation error affects only monomer relaxation (deformation) energies and behaves similarly to bond-dissociation energy errors. Delocalization and deformation errors affect systems with significant intermolecular orbital interactions (e.g., hydrogen- and halogen-bonded systems), whereas repulsion error is ubiquitous. Many-body errors from the underlying exchange-correlation functional greatly exceed in general the magnitude of the many-body dispersion energy term. A functional built to accurately model noncovalent interactions must contain a dispersion correction, semilocal exchange, and correlation components that minimize the repulsion error independently and must also incorporate exact exchange in such a way that delocalization error is absent.

Do all pure entangled states violate Bell's inequalities for correlation functions?

Science.gov (United States)

Zukowski, Marek; Brukner, Caslav; Laskowski, Wiesław; Wieśniak, Marcin

2002-05-27

Any pure entangled state of two particles violates a Bell inequality for two-particle correlation functions (Gisin's theorem). We show that there exist pure entangled N>2 qubit states that do not violate any Bell inequality for N particle correlation functions for experiments involving two dichotomic observables per local measuring station. We also find that Mermin-Ardehali-Belinskii-Klyshko inequalities may not always be optimal for refutation of local realistic description.

Characterization of topological phases of dimerized Kitaev chain via edge correlation functions

Science.gov (United States)

Wang, Yucheng; Miao, Jian-Jian; Jin, Hui-Ke; Chen, Shu

2017-11-01

We study analytically topological properties of a noninteracting modified dimerized Kitaev chain and an exactly solvable interacting dimerized Kitaev chain under open boundary conditions by analyzing two introduced edge correlation functions. The interacting dimerized Kitaev chain at the symmetry point Δ =t and the chemical potential μ =0 can be exactly solved by applying two Jordan-Wigner transformations and a spin rotation, which permits us to calculate the edge correlation functions analytically. We demonstrate that the two edge correlation functions can be used to characterize the trivial, Su-Schrieffer-Heeger-like topological and topological superconductor phases of both the noninteracting and interacting systems and give their phase diagrams.

Correlation functions formed by a femtosecond pulse interferometer

NARCIS (Netherlands)

Cui, M.; Bhattacharya, N.; Urbach, H.P.; Van den berg, S.A.

2008-01-01

We experimentally demonstrate that a stabilized femtosecond frequency comb can be applied as a tool for distance measurement. The scheme is based on optical interference between individual pulses in a Michelson type interferometer. The cross-correlation functions between individual pulses with a

Electron Correlation from the Adiabatic Connection for Multireference Wave Functions

Science.gov (United States)

Pernal, Katarzyna

2018-01-01

An adiabatic connection (AC) formula for the electron correlation energy is derived for a broad class of multireference wave functions. The AC expression recovers dynamic correlation energy and assures a balanced treatment of the correlation energy. Coupling the AC formalism with the extended random phase approximation allows one to find the correlation energy only from reference one- and two-electron reduced density matrices. If the generalized valence bond perfect pairing model is employed a simple closed-form expression for the approximate AC formula is obtained. This results in the overall M5 scaling of the computation cost making the method one of the most efficient multireference approaches accounting for dynamic electron correlation also for the strongly correlated systems.

Two-body correlation functions in dilute nuclear matter

International Nuclear Information System (INIS)

Isayev, A A

2006-01-01

Finding the distinct features of the crossover from the regime of large overlapping Cooper pairs to the limit of non-overlapping pairs of fermions (Shafroth pairs) in multicomponent Fermi systems remains one of the actual problems in a quantum many-body theory. Here this transition is studied by calculating the two-body density, spin and isospin correlation functions in dilute asymmetric nuclear matter. It is shown that criterion of the crossover (Phys. Rev. Lett. 95, 090402 (2005)), consisting in the change of the sign of the density correlation function at low momentum transfer, fails to describe correctly the density-driven BEC-BCS transition at finite isospin asymmetry or finite temperature. As an unambiguous signature of the BEC-BCS transition, there can be used the presence (BCS regime) or absence (BEC regime) of the singularity in the momentum distribution of the quasiparticle density of states

Correlations between motor and sensory functions in upper limb chronic hemiparetics after stroke

Directory of Open Access Journals (Sweden)

Thais Botossi Scalha

2011-08-01

Full Text Available OBJECTIVE: Describe the somatosensory function of the affected upper limb of hemiparetic stroke patients and investigate the correlations between measurements of motor and sensory functions in tasks with and without visual deprivation. METHOD: We applied the Fugl-Meyer Assessment (FMA, Nottingham Sensory Assessment (NSA, and several motor and sensory tests: Paper manipulation (PM, Motor Sequences (MS, Reaching and grasping (RG Tests Functional (TF, Tactile Discrimination (TD, Weight Discrimination (WD and Tactile Recognition of Objects (RO. RESULTS: We found moderate correlations between the FMA motor subscale and the tactile sensation score of the NSA. Additionally, the FMA sensitivity was correlated with the NSA total; and performance on the WD test items correlated with the NSA. CONCLUSION: There was a correlation between the sensory and motor functions of the upper limb in chronic hemiparetic stroke patients. Additionally, there was a greater reliance on visual information to compensate for lost sensory-motor skills.

Correlation functions of the chiral stress-tensor multiplet in $ \\mathcal{N}=4 $ SYM

CERN Document Server

Chicherin, Dmitry; Eden, Burkhard; Heslop, Paul; Korchemsky, Gregory P.; Mason, Lionel; Sokatchev, Emery

2015-01-01

We give a new method for computing the correlation functions of the chiral part of the stress-tensor supermultiplet that relies on the reformulation of N=4 SYM in twistor space. It yields the correlation functions in the Born approximation as a sum of Feynman diagrams on twistor space that involve only propagators and no integration vertices. We use this unusual feature of the twistor Feynman rules to compute the correlation functions in terms of simple building blocks which we identify as a new class of N=4 off-shell superconformal invariants. Making use of the duality between correlation functions and planar scattering amplitudes, we demonstrate that these invariants represent an off-shell generalisation of the on-shell invariants defining tree-level scattering amplitudes in N=4 SYM.

Quantum spin correction scheme based on spin-correlation functional for Kohn-Sham spin density functional theory

International Nuclear Information System (INIS)

Yamanaka, Shusuke; Takeda, Ryo; Nakata, Kazuto; Takada, Toshikazu; Shoji, Mitsuo; Kitagawa, Yasutaka; Yamaguchi, Kizashi

2007-01-01

We present a simple quantum correction scheme for ab initio Kohn-Sham spin density functional theory (KS-SDFT). This scheme is based on a mapping from ab initio results to a Heisenberg model Hamiltonian. The effective exchange integral is estimated by using energies and spin correlation functionals calculated by ab initio KS-SDFT. The quantum-corrected spin-correlation functional is open to be designed to cover specific quantum spin fluctuations. In this article, we present a simple correction for dinuclear compounds having multiple bonds. The computational results are discussed in relation to multireference (MR) DFT, by which we treat the quantum many-body effects explicitly

Triglycerides are negatively correlated with cognitive function in nondemented aging adults.

Science.gov (United States)

Parthasarathy, Vishnu; Frazier, Darvis T; Bettcher, Brianne M; Jastrzab, Laura; Chao, Linda; Reed, Bruce; Mungas, Dan; Weiner, Michael; DeCarli, Charles; Chui, Helena; Kramer, Joel H

2017-09-01

Vascular risk factors like hyperlipidemia may adversely affect brain function. We hypothesized that increased serum triglycerides are associated with decreased executive function and memory in nondemented elderly subjects. We also researched possible vascular mediators and white matter microstructure as assessed with diffusion tensor imaging (DTI). Participants were 251 nondemented elderly adults (54% male) with a mean age of 78 (SD = 6.4; range: 62-94) years and a mean education of 15.6 (SD = 2.9; range: 8-23) years. Fasting blood samples were used to detect serum triglyceride and low-density lipoprotein (LDL) levels along with ApoE4 status. DTI was used to determine whole brain fractional anisotropy (FA). Composite executive and memory scores were derived from item response theory. Clinical Dementia Rating (CDR) scores provided informant-based measures of daily functioning. Triglyceride levels were inversely correlated with executive function, but there was no relationship with memory. Controlling for age, gender, and education did not affect this correlation. This relationship persisted after controlling for vascular risk factors like LDL, total cholesterol, CDR and ApoE4 status. Lastly, adding whole-brain FA to the model did not affect the correlation between triglycerides and executive function. Triglyceride levels are inversely correlated with executive function in nondemented elderly adults after controlling for age, education, gender, total cholesterol, LDL, ApoE4 status, CDR, and white-matter microstructure. The fact that the effect of triglycerides on cognition was not clearly mediated by vascular risks or cerebrovascular injury raises questions about widely held assumptions of how triglycerides might impact cognition function. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Structurofunctional resting-state networks correlate with motor function in chronic stroke

Directory of Open Access Journals (Sweden)

Benjamin T. Kalinosky

2017-01-01

Conclusion: The results demonstrate that changes after a stroke in both intrinsic and network-based structurofunctional correlations at rest are correlated with motor function, underscoring the importance of residual structural connectivity in cortical networks.

On minimizing the influence of the noise tail of correlation functions in operational modal analysis

DEFF Research Database (Denmark)

Tarpø, Marius; Olsen, Peter; Amador, Sandro

2017-01-01

on the identification results (random errors) when the noise tail is included in the identification. On the other hand, if the correlation function is truncated too much, then important information is lost. In other to minimize this error, a suitable truncation based on manual inspection of the correlation function......In operational modal analysis (OMA) correlation functions are used by all classical time-domain modal identification techniques that uses the impulse response function (free decays) as primary data. However, the main difference between the impulse response and the correlation functions estimated...... from the operational responses is that the latter present a higher noise level. This is due to statistical errors in the estimation of the correlation function and it causes random noise in the end of the function and this is called the noise tail. This noise might have significant influence...

Combination of Wavefunction and Density Functional Approximations for Describing Electronic Correlation

Science.gov (United States)

Garza, Alejandro J.

Perhaps the most important approximations to the electronic structure problem in quantum chemistry are those based on coupled cluster and density functional theories. Coupled cluster theory has been called the ``gold standard'' of quantum chemistry due to the high accuracy that it achieves for weakly correlated systems. Kohn-Sham density functionals based on semilocal approximations are, without a doubt, the most widely used methods in chemistry and material science because of their high accuracy/cost ratio. The root of the success of coupled cluster and density functionals is their ability to efficiently describe the dynamic part of the electron correlation. However, both traditional coupled cluster and density functional approximations may fail catastrophically when substantial static correlation is present. This severely limits the applicability of these methods to a plethora of important chemical and physical problems such as, e.g., the description of bond breaking, transition states, transition metal-, lanthanide- and actinide-containing compounds, and superconductivity. In an attempt to tackle this problem, nonstandard (single-reference) coupled cluster-based techniques that aim to describe static correlation have been recently developed: pair coupled cluster doubles (pCCD) and singlet-paired coupled cluster doubles (CCD0). The ability to describe static correlation in pCCD and CCD0 comes, however, at the expense of important amounts of dynamic correlation so that the high accuracy of standard coupled cluster becomes unattainable. Thus, the reliable and efficient description of static and dynamic correlation in a simultaneous manner remains an open problem for quantum chemistry and many-body theory in general. In this thesis, different ways to combine pCCD and CCD0 with density functionals in order to describe static and dynamic correlation simultaneously (and efficiently) are explored. The combination of wavefunction and density functional methods has a long

CORRELATION BETWEEN CERVICAL SAGITTAL ALIGNMENT AND FUNCTIONAL CAPACITY IN CERVICAL SPONDYLOSIS

Directory of Open Access Journals (Sweden)

Marcel Machado da Motta

Full Text Available ABSTRACT Objective: To correlate the radiographic parameters of sagittal cervical alignment with quality of life and functional capacity in patients with cervical spondylosis under conservative treatment. Methods: This is an observational and prospective study in patients with cervical spondylosis under conservative treatment and without indication for surgery. The 52 patients included were divided into three groups: axial pain, radiculopathy, and cervical myelopathy. The radiographic parameters considered were cervical lordosis (CL, cervical sagittal vertical axis (CSVA, T1 slope (TS and the discrepancy between TS and CL (TS-CL. Quality of life and functional capacity were evaluated by the Neck Disability Index (NDI questionnaire. Pain was assessed by the Visual Analogue Scale (VAS. The correlation between the radiographic parameters and the clinical scores was evaluated by the Pearson correlations coefficient. Results: There was no difference in cervical radiographic parameters between the three groups. In the total of the sample, the mean value of the CSVA was 17.8o (±8.3o, CL, 22.4° (± 8.8°; TS, 29.3° (±6.6°, and TS-CL, 7.0° (±7.4°. Significant inverse correlation (r= -0.3, p=0.039 was observed between NDI and CL, but there was no significant correlation between CL and VAS. CSVA (p=0.541, TS (p=0.287 and TS-CL (p=0.287 had no significantly correlated with NDI or VAS. Conclusion: Considering patients with cervical spondylosis not candidates for surgery, the only sagittal parameter that correlated with functional capacity was LC. In these patients, the correlation between cervical alignment and quality of life needs to be better characterized.

Correlates of sexual function in male and female patients with multiple sclerosis.

Science.gov (United States)

Lew-Starowicz, Michal; Rola, Rafal

2014-09-01

Many factors have been suggested to contribute to sexual dysfunction (SD) in multiple sclerosis (MS) patients, but the research on their impact on sexual functioning (SF) and sexual quality of life (SQoL) remains scant. The aim of this study was to investigate correlates of SF and SQoL in MS patients, as well as possible gender differences. 204 MS patients were interviewed, completed the questionnaires, and underwent neurological assessment. Primary outcome measures included the International Index of Erectile Function, the Female Sexual Function Questionnaire, the Sexual Quality of Life Questionnaire, the Beck Depression Inventory, and the Expanded Disability Status Scale. The course and duration of the disease did not predict patients' SF. Negative correlations were found for brainstem symptoms with orgasmic function and overall satisfaction in men and between cognitive functioning and the partner domain in women. Interestingly, brainstem symptoms correlated positively with the arousal domain in women. More than half (52.1%) of patients fulfilled Beck Depression Inventory criteria for depression, and these patients showed more SD than nondepressive individuals. The strongest negative correlations with depressive symptoms were found for desire, erectile function, and overall satisfaction with sexual life in men and for orgasm and sexual enjoyment in women. Deterioration in particular domains of SF was clearly related with diminished SQoL. The main gender difference was a strong influence of decreased desire on SQoL in women and no such correlation in men. Negative assessment of the relationship with partner significantly affected all domains of SF and SQoL in MS women and the desire domain in MS men. Several correlates of SF in MS patients were found. The role of brainstem symptoms needs further investigation. Clinicians should pay close attention to depressive symptoms and relationship factors in MS patients who suffer from SD. © 2014 International Society for

Correlation between Cognitive Functions and Activity of Daily Living among Post-Stroke Patients

Directory of Open Access Journals (Sweden)

Kurniawan Prakoso

2016-09-01

Full Text Available Background: Cognitive impairment is one of the most common post-stroke complications; however, neither patients nor health professionals are often aware of this complication. The impact of cognitive impairment on quality of life is reflected through basic activity daily living (bADL and instrumental activity daily living (IADL. Prior studies concerning the correlation between cognitive impairment and activity daily living has shown contradictive results. This study was conducted in order to analyze the correlation between the cognitive functions and activity daily living in post stroke patients at Dr. Hasan Sadikin General Hospital. Methods: This cross-sectional study was carried out to 23 post-stroke patients from September–November 2015. Samples were collected through consecutive sampling at Dr. Hasan Sadikin General Hospital. Mini Mental State Examination (MMSE was used to assess the cognitive functions and Lawton and Brody Scale to assess both bADL and IADL. Spearman correlation was selected to analyze the existing correlation between each cognitive domain and activity daily living. Results: Spearman statistical correlation showed an insignificant correlation between the cognitive functions and bADL (r2=0.181, p=0.408 and a significant correlation with IADL was obtained (r2=0.517, p=0.03. The only cognitive domain positively correlated with IADL was orientation to time and verbal recall. Conclusions: There is a correlation between cognitive functions and IADL among post-stroke patients at Dr. Hasan Sadikin General Hospital.

Correlation of 68Ga Ventilation-Perfusion PET/CT with Pulmonary Function Test Indices for Assessing Lung Function.

Science.gov (United States)

Le Roux, Pierre-Yves; Siva, Shankar; Steinfort, Daniel P; Callahan, Jason; Eu, Peter; Irving, Lou B; Hicks, Rodney J; Hofman, Michael S

2015-11-01

Pulmonary function tests (PFTs) are routinely used to assess lung function, but they do not provide information about regional pulmonary dysfunction. We aimed to assess correlation of quantitative ventilation-perfusion (V/Q) PET/CT with PFT indices. Thirty patients underwent V/Q PET/CT and PFT. Respiration-gated images were acquired after inhalation of (68)Ga-carbon nanoparticles and administration of (68)Ga-macroaggregated albumin. Functional volumes were calculated by dividing the volume of normal ventilated and perfused (%NVQ), unmatched and matched defects by the total lung volume. These functional volumes were correlated with forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC, and diffusing capacity for carbon monoxide (DLCO). All functional volumes were significantly different in patients with chronic obstructive pulmonary disease (P volume of unmatched defects (r = -0.55). Considering %NVQ only, a cutoff value of 90% correctly categorized 28 of 30 patients with or without significant pulmonary function impairment. Our study demonstrates strong correlations between V/Q PET/CT functional volumes and PFT parameters. Because V/Q PET/CT is able to assess regional lung function, these data support the feasibility of its use in radiation therapy and preoperative planning and assessing pulmonary dysfunction in a variety of respiratory diseases. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Structure functions and correlations in nuclei

International Nuclear Information System (INIS)

Schiavilla, R.; Lewart, D.S.; Pandharipande, V.R.

1987-01-01

The static longitudinal structure function S l (k) and the static structure function S(k) of 3 H, 3 He and 4 He nuclei and nuclear matter are calculated using realistic wave functions obtained from Faddeev and variational calculations. In order to study the variation of the structure function with the number of particles in the system we also calculate S(k) of atomic helium liquid drops containing 4, 8, 20, 40, 70, 168 and 240 atoms. Monte Carlo integration is used to calculate the structure functions of finite systems, while those of nuclear matter are calculated with chain summation methods. The behaivior of S(k) and S l (k) at small values of k is discussed. We find that the recent Saclay data on S l (k) of the 3 He nucleus are in agreement with theory. Though the data indicate the the existence of correlations between the two protons in the 3 He nucleus, they are not accurate enough to draw interesting conclusions about the repulsive core in the nucleon-nucleon interaction. The structure functions of atomic helium liquid drops indicate a smooth variation of S(k) with the number of atoms in the drop. The S L (k) of the 4 He nucleus and nuclear matter are very similar for k > 1.5 fm -1 , and it appears plausible that S L (k) of nuclei having A > 3 may not depend significantly on A when k > 1.5 fm -1 . (orig.)

The Self-Correlation Function of Real Gases

International Nuclear Information System (INIS)

Sigmar, D.J.

1965-01-01

In the formal theory of inelastic scattering of neutrons, the self-correlation function has been worked out in terms of statistical averages of the derivatives of die N-body interaction-potential of the scatterer. In the present paper, these averages are evaluated for real gases by means of a cluster-expansion related to that of Mayer-Ursell. This leads to certain non-linear types of clusters, which are investigated with respect to the topology of the graphs, their multiplicity (by combinatorial analysis) and their quadrature. As one expects, in view of the many-body problem, some of the clusters are not separable and have to be machine-integrated. In this way, the self-correlation function γ s (K, t) is cálculated for short times, including also the first non-Gaussian term. The cluster-expansion breaks off after the first interaction term, so that the results are valid for low density only. This still gives rise to very many different types of clusters, containing up to seven points, for each coefficient. The assumed potential is a general two-particle, hard-core type. As Singwi et al. have shown, the long time behaviour of γs is determined by the time integral of the velocity auto-correlation: ∫ ∞ 0 K (0) V K (t) > T dt. To construct the integrand for all times, we can make use of our cluster-expansion for small t and adopt Langevin’s diffusion theory for large t. Numerical computations are under way. (author) [fr

Correlation Functions of the One-Dimensional Attractive Bose Gas

International Nuclear Information System (INIS)

Calabrese, Pasquale; Caux, Jean-Sebastien

2007-01-01

The zero-temperature correlation functions of the one-dimensional attractive Bose gas with a delta-function interaction are calculated analytically for any value of the interaction parameter and number of particles, directly from the integrability of the model. We point out a number of interesting features, including zero recoil energy for a large number of particles, analogous to the Moessbauer effect

On Montgomery's pair correlation conjecture to the zeros of Riedmann zeta function

OpenAIRE

Li, Pei

2005-01-01

In this thesis, we are interested in Montgomery's pair correlation conjecture which is about the distribution of.the spacings between consecutive zeros of the Riemann Zeta function. Our goal is to explain and study Montgomery's pair correlation conjecture and discuss its connection with the random matrix theory. In Chapter One, we will explain how to define the Ftiemann Zeta function by using the analytic continuation. After this, several classical properties of the Ftiemann Zeta function wil...

COMPUTER HARDWARE MARKING

CERN Multimedia

Groupe de protection des biens

2000-01-01

As part of the campaign to protect CERN property and for insurance reasons, all computer hardware belonging to the Organization must be marked with the words 'PROPRIETE CERN'.IT Division has recently introduced a new marking system that is both economical and easy to use. From now on all desktop hardware (PCs, Macintoshes, printers) issued by IT Division with a value equal to or exceeding 500 CHF will be marked using this new system.For equipment that is already installed but not yet marked, including UNIX workstations and X terminals, IT Division's Desktop Support Service offers the following services free of charge:Equipment-marking wherever the Service is called out to perform other work (please submit all work requests to the IT Helpdesk on 78888 or helpdesk@cern.ch; for unavoidable operational reasons, the Desktop Support Service will only respond to marking requests when these coincide with requests for other work such as repairs, system upgrades, etc.);Training of personnel designated by Division Leade...

Epistemic stance marking in the use of English as a lingua franca

DEFF Research Database (Denmark)

Mortensen, Janus

A comparative study of the pragmatic functions of epistemic stance marking in problem-solving sequences at student project group meetings, with special emphasis on meetings where English is used as a lingua franca......A comparative study of the pragmatic functions of epistemic stance marking in problem-solving sequences at student project group meetings, with special emphasis on meetings where English is used as a lingua franca...

A new quantum statistical evaluation method for time correlation functions

International Nuclear Information System (INIS)

Loss, D.; Schoeller, H.

1989-01-01

Considering a system of N identical interacting particles, which obey Fermi-Dirac or Bose-Einstein statistics, the authors derive new formulas for correlation functions of the type C(t) = i= 1 N A i (t) Σ j=1 N B j > (where B j is diagonal in the free-particle states) in the thermodynamic limit. Thereby they apply and extend a superoperator formalism, recently developed for the derivation of long-time tails in semiclassical systems. As an illustrative application, the Boltzmann equation value of the time-integrated correlation function C(t) is derived in a straight-forward manner. Due to exchange effects, the obtained t-matrix and the resulting scattering cross section, which occurs in the Boltzmann collision operator, are now functionals of the Fermi-Dirac or Bose-Einstein distribution

A Unified Approach to Functional Principal Component Analysis and Functional Multiple-Set Canonical Correlation.

Science.gov (United States)

Choi, Ji Yeh; Hwang, Heungsun; Yamamoto, Michio; Jung, Kwanghee; Woodward, Todd S

2017-06-01

Functional principal component analysis (FPCA) and functional multiple-set canonical correlation analysis (FMCCA) are data reduction techniques for functional data that are collected in the form of smooth curves or functions over a continuum such as time or space. In FPCA, low-dimensional components are extracted from a single functional dataset such that they explain the most variance of the dataset, whereas in FMCCA, low-dimensional components are obtained from each of multiple functional datasets in such a way that the associations among the components are maximized across the different sets. In this paper, we propose a unified approach to FPCA and FMCCA. The proposed approach subsumes both techniques as special cases. Furthermore, it permits a compromise between the techniques, such that components are obtained from each set of functional data to maximize their associations across different datasets, while accounting for the variance of the data well. We propose a single optimization criterion for the proposed approach, and develop an alternating regularized least squares algorithm to minimize the criterion in combination with basis function approximations to functions. We conduct a simulation study to investigate the performance of the proposed approach based on synthetic data. We also apply the approach for the analysis of multiple-subject functional magnetic resonance imaging data to obtain low-dimensional components of blood-oxygen level-dependent signal changes of the brain over time, which are highly correlated across the subjects as well as representative of the data. The extracted components are used to identify networks of neural activity that are commonly activated across the subjects while carrying out a working memory task.

CCFpams: Atmospheric stellar parameters from cross-correlation functions

Science.gov (United States)

Malavolta, Luca; Lovis, Christophe; Pepe, Francesco; Sneden, Christopher; Udry, Stephane

2017-07-01

CCFpams allows the measurement of stellar temperature, metallicity and gravity within a few seconds and in a completely automated fashion. Rather than performing comparisons with spectral libraries, the technique is based on the determination of several cross-correlation functions (CCFs) obtained by including spectral features with different sensitivity to the photospheric parameters. Literature stellar parameters of high signal-to-noise (SNR) and high-resolution HARPS spectra of FGK Main Sequence stars are used to calibrate the stellar parameters as a function of CCF areas.

Attentional Capture to a Singleton Distractor Degrades Visual Marking in Visual Search

Directory of Open Access Journals (Sweden)

Kenji Yamauchi

2017-05-01

Full Text Available Visual search is easier after observing some distractors in advance; it is as if the previewed distractors were excluded from the search. This effect is referred to as the preview benefit, and a memory template that visually marks the old locations of the distractors is thought to help in prioritizing the locations of newly presented items. One remaining question is whether the presence of a conspicuous item during the sequential shift of attention within the new items reduces this preview benefit. To address this issue, we combined the above preview search and a conventional visual search paradigm using a singleton distractor and examined whether the search performance was affected by the presence of the singleton. The results showed that the slope of reaction time as a function of set size became steeper in the presence of a singleton, indicating that the singleton distractor reduced the preview benefit. Furthermore, this degradation effect was positively correlated with the degree of conventional attentional capture to a singleton measured in a separate experiment with simultaneous search. These findings suggest that the mechanism of visual marking shares common attentional resources with the search process.

Operator theory of angular momentum nad orientational auto-correlation functions

International Nuclear Information System (INIS)

Evans, M.W.

1982-01-01

The rigorous relation between the orientational auto-correlation function and the angular momentum autocorrelation function is described in two cases of interest. First when description of the complete zero THz- spectrum is required from the Mori continued fraction expansion for the angular momentum autocorrelation function and second when rotation/translation effects are important. The Mori-Evans theory of 1976, relying on the simple Shimizu relation is found to be essentially unaffected by the higher order corrections recently worked out by Ford and co-workers in the Markov limit. The mutual interaction of rotation and translation is important in determining the details of both the orientational and angular momentum auto-correlation function's (a.c.f.'s) in the presence of sample anisotropy or a symmetry breaking field. In this case it is essential to regard the angular momentum a.c.f. as non-Markovian and methods are developed to relate this to the orientational a.c.f. in the presence of rotation/translation coupling. (author)

Performance of exchange-correlation functionals in density functional theory calculations for liquid metal: A benchmark test for sodium

Science.gov (United States)

Han, Jeong-Hwan; Oda, Takuji

2018-04-01

The performance of exchange-correlation functionals in density-functional theory (DFT) calculations for liquid metal has not been sufficiently examined. In the present study, benchmark tests of Perdew-Burke-Ernzerhof (PBE), Armiento-Mattsson 2005 (AM05), PBE re-parameterized for solids, and local density approximation (LDA) functionals are conducted for liquid sodium. The pair correlation function, equilibrium atomic volume, bulk modulus, and relative enthalpy are evaluated at 600 K and 1000 K. Compared with the available experimental data, the errors range from -11.2% to 0.0% for the atomic volume, from -5.2% to 22.0% for the bulk modulus, and from -3.5% to 2.5% for the relative enthalpy depending on the DFT functional. The generalized gradient approximation functionals are superior to the LDA functional, and the PBE and AM05 functionals exhibit the best performance. In addition, we assess whether the error tendency in liquid simulations is comparable to that in solid simulations, which would suggest that the atomic volume and relative enthalpy performances are comparable between solid and liquid states but that the bulk modulus performance is not. These benchmark test results indicate that the results of liquid simulations are significantly dependent on the exchange-correlation functional and that the DFT functional performance in solid simulations can be used to roughly estimate the performance in liquid simulations.

The elimination of singularities in pair correlation functions of a multicomponent liquid system

International Nuclear Information System (INIS)

Vasil'jev, O.M.; Chalij, O.V.

2004-01-01

In this paper we propose a method that allows to find nonsingular expressions for pair correlation functions of a multicomponent liquid system. The nature of the method deals with using integral and differential Ornstein-Zernike equations for finding asymptotic expressions for pair correlation functions and their subsequent precision. The obtained results are analyzed taking into account their possible applicability for studying the correlative behaviour of multicomponent liquid systems

Correlation functions and Schwinger-Dyson equations for Penner's model

International Nuclear Information System (INIS)

Chair, N.; Panda, S.

1991-05-01

The free energy of Penner's model exhibits logarithmic singularity in the continuum limit. We show, however, that the one and two point correlators of the usual loop-operators do not exhibit logarithmic singularity. The continuum Schwinger-Dyson equations involving these correlation functions are derived and it is found that within the space of the corresponding couplings, the resulting constraints obey a Virasoro algebra. The puncture operator having the correct (logarithmic) scaling behaviour is identified. (author). 13 refs

Dynamic polarization in paramagnetic solids and microscopic correlation functions

International Nuclear Information System (INIS)

Boucher, Jean-Paul

1972-01-01

The different effects of Dynamic Nuclear Polarization in paramagnetic solids are described by means of a single thermodynamic formalism. In the case of large exchange interactions, the Overhauser effect correlated with nuclear relaxation time measurements can provide a way of studying correlation functions between electronic spins. This method is used to study the low-frequency behaviour of the microscopic spectral density which should diverge as ω → 0, in the case of a linear exchange chain. (author) [fr

The asymptotic behaviour of the maximum likelihood function of Kriging approximations using the Gaussian correlation function

CSIR Research Space (South Africa)

Kok, S

2012-07-01

Full Text Available continuously as the correlation function hyper-parameters approach zero. Since the global minimizer of the maximum likelihood function is an asymptote in this case, it is unclear if maximum likelihood estimation (MLE) remains valid. Numerical ill...

A local dynamic correlation function from inelastic neutron scattering

International Nuclear Information System (INIS)

McQueeney, R.J.

1997-01-01

Information about local and dynamic atomic correlations can be obtained from inelastic neutron scattering measurements by Fourier transform of the Q-dependent intensity oscillations at a particular frequency. A local dynamic structure function, S(r,ω), is defined from the dynamic scattering function, S(Q,ω), such that the elastic and frequency-integrated limits correspond to the average and instantaneous pair-distribution functions, respectively. As an example, S(r,ω) is calculated for polycrystalline aluminum in a model where atomic motions are entirely due to harmonic phonons

Kohn-Sham density functional theory for quantum wires in arbitrary correlation regimes

NARCIS (Netherlands)

Malet, F.; Mirtschink, A.P.; Cremon, J. C.; Reimann, S. M.; Gori Giorgi, P.

2013-01-01

We use the exact strong-interaction limit of the Hohenberg-Kohn energy density functional to construct an approximation for the exchange-correlation term of the Kohn-Sham approach. The resulting exchange-correlation potential is able to capture the features of the strongly correlated regime without

Cognitive, neurophysiological, and functional correlates of proverb interpretation abnormalities in schizophrenia.

Science.gov (United States)

Kiang, Michael; Light, Gregory A; Prugh, Jocelyn; Coulson, Seana; Braff, David L; Kutas, Marta

2007-07-01

A hallmark of schizophrenia is impaired proverb interpretation, which could be due to: (1) aberrant activation of disorganized semantic associations, or (2) working memory (WM) deficits. We assessed 18 schizophrenia patients and 18 normal control participants on proverb interpretation, and evaluated these two hypotheses by examining within patients the correlations of proverb interpretation with disorganized symptoms and auditory WM, respectively. Secondarily, we also explored the relationships between proverb interpretation and a spectrum of cognitive functions including auditory sensory-memory encoding (as indexed by the mismatch negativity (MMN) event-related brain potential (ERP)); executive function; and social/occupational function. As expected, schizophrenia patients produced less accurate and less abstract descriptions of proverbs than did controls. These proverb interpretation difficulties in patients were not significantly correlated with disorganization or other symptom factors, but were significantly correlated (p proverb interpretation in schizophrenia, but implicate WM deficits, perhaps as a part of a syndrome related to generalized frontal cortical dysfunction.

The correlation function for density perturbations in an expanding universe. II - Nonlinear theory

Science.gov (United States)

Mcclelland, J.; Silk, J.

1977-01-01

A formalism is developed to find the two-point and higher-order correlation functions for a given distribution of sizes and shapes of perturbations which are randomly placed in three-dimensional space. The perturbations are described by two parameters such as central density and size, and the two-point correlation function is explicitly related to the luminosity function of groups and clusters of galaxies

Modeling fractal structure of city-size distributions using correlation functions.

Science.gov (United States)

Chen, Yanguang

2011-01-01

Zipf's law is one the most conspicuous empirical facts for cities, however, there is no convincing explanation for the scaling relation between rank and size and its scaling exponent. Using the idea from general fractals and scaling, I propose a dual competition hypothesis of city development to explain the value intervals and the special value, 1, of the power exponent. Zipf's law and Pareto's law can be mathematically transformed into one another, but represent different processes of urban evolution, respectively. Based on the Pareto distribution, a frequency correlation function can be constructed. By scaling analysis and multifractals spectrum, the parameter interval of Pareto exponent is derived as (0.5, 1]; Based on the Zipf distribution, a size correlation function can be built, and it is opposite to the first one. By the second correlation function and multifractals notion, the Pareto exponent interval is derived as [1, 2). Thus the process of urban evolution falls into two effects: one is the Pareto effect indicating city number increase (external complexity), and the other the Zipf effect indicating city size growth (internal complexity). Because of struggle of the two effects, the scaling exponent varies from 0.5 to 2; but if the two effects reach equilibrium with each other, the scaling exponent approaches 1. A series of mathematical experiments on hierarchical correlation are employed to verify the models and a conclusion can be drawn that if cities in a given region follow Zipf's law, the frequency and size correlations will follow the scaling law. This theory can be generalized to interpret the inverse power-law distributions in various fields of physical and social sciences.

Distinguishing butchery cut marks from crocodile bite marks through machine learning methods.

Science.gov (United States)

Domínguez-Rodrigo, Manuel; Baquedano, Enrique

2018-04-10

All models of evolution of human behaviour depend on the correct identification and interpretation of bone surface modifications (BSM) on archaeofaunal assemblages. Crucial evolutionary features, such as the origin of stone tool use, meat-eating, food-sharing, cooperation and sociality can only be addressed through confident identification and interpretation of BSM, and more specifically, cut marks. Recently, it has been argued that linear marks with the same properties as cut marks can be created by crocodiles, thereby questioning whether secure cut mark identifications can be made in the Early Pleistocene fossil record. Powerful classification methods based on multivariate statistics and machine learning (ML) algorithms have previously successfully discriminated cut marks from most other potentially confounding BSM. However, crocodile-made marks were marginal to or played no role in these comparative analyses. Here, for the first time, we apply state-of-the-art ML methods on crocodile linear BSM and experimental butchery cut marks, showing that the combination of multivariate taphonomy and ML methods provides accurate identification of BSM, including cut and crocodile bite marks. This enables empirically-supported hominin behavioural modelling, provided that these methods are applied to fossil assemblages.

Urinary NGAL marks cystic disease in HIV-associated nephropathy.

Science.gov (United States)

Paragas, Neal; Nickolas, Thomas L; Wyatt, Christina; Forster, Catherine S; Sise, Meghan; Morgello, Susan; Jagla, Bernd; Buchen, Charles; Stella, Peter; Sanna-Cherchi, Simone; Carnevali, Maria Luisa; Mattei, Silvia; Bovino, Achiropita; Argentiero, Lucia; Magnano, Andrea; Devarajan, Prasad; Schmidt-Ott, Kai M; Allegri, Landino; Klotman, Paul; D'Agati, Vivette; Gharavi, Ali G; Barasch, Jonathan

2009-08-01

Nephrosis and a rapid decline in kidney function characterize HIV-associated nephropathy (HIVAN). Histologically, HIVAN is a collapsing focal segmental glomerulosclerosis with prominent tubular damage. We explored the expression of neutrophil gelatinase-associated lipocalin (NGAL), a marker of tubular injury, to determine whether this protein has the potential to aid in the noninvasive diagnosis of HIVAN. We found that expression of urinary NGAL was much higher in patients with biopsy-proven HIVAN than in HIV-positive and HIV-negative patients with other forms of chronic kidney disease. In the HIV-transgenic mouse model of HIVAN, NGAL mRNA was abundant in dilated, microcystic segments of the nephron. In contrast, urinary NGAL did not correlate with proteinuria in human or in mouse models. These data show that marked upregulation of NGAL accompanies HIVAN and support further study of uNGAL levels in large cohorts to aid in the noninvasive diagnosis of HIVAN and screen for HIVAN-related tubular damage.

[Correlation analysis between residual displacement and hip function after reconstruction of acetabular fractures].

Science.gov (United States)

Ma, Kunlong; Fang, Yue; Luan, Fujun; Tu, Chongqi; Yang, Tianfu

2012-03-01

To investigate the relationships between residual displacement of weight-bearing and non weight-bearing zones (gap displacement and step displacement) and hip function by analyzing the CT images after reconstruction of acetabular fractures. The CT measures and clinical outcome were retrospectively analyzed from 48 patients with displaced acetabular fracture between June 2004 and June 2009. All patients were treated by open reduction and internal fixation, and were followed up 24 to 72 months (mean, 36 months); all fractures healed after operation. The residual displacement involved the weight-bearing zone in 30 cases (weight-bearing group), and involved the non weight-bearing zone in 18 cases (non weight-bearing group). The clinical outcomes were evaluated by Merle d'Aubigné-Postel criteria, and the reduction of articular surface by CT images, including the maximums of two indexes (gap displacement and step displacement). All the data were analyzed in accordance with the Spearman rank correlation coefficient analysis. There was strong negative correlation between the hip function and the residual displacement values in weight-bearing group (r(s) = -0.722, P = 0.001). But there was no correlation between the hip function and the residual displacement values in non weight-bearing group (r(s) = 0.481, P = 0.059). The results of clinical follow-up were similar to the correlation analysis results. In weight-bearing group, the hip function had strong negative correlation with step displacement (r(s) = 0.825, P = 0.002), but it had no correlation with gap displacement (r(s) = 0.577, P = 0.134). In patients with acetabular fracture, the hip function has correlation not only with the extent of the residual displacement but also with the location of the residual displacement, so the residual displacement of weight-bearing zone is a key factor to affect the hip function. In patients with residual displacement in weight-bearing zone, the bigger the step displacement is, the

An improved method for estimating the frequency correlation function

KAUST Repository

Chelli, Ali; Pä tzold, Matthias

2012-01-01

For time-invariant frequency-selective channels, the transfer function is a superposition of waves having different propagation delays and path gains. In order to estimate the frequency correlation function (FCF) of such channels, the frequency averaging technique can be utilized. The obtained FCF can be expressed as a sum of auto-terms (ATs) and cross-terms (CTs). The ATs are caused by the autocorrelation of individual path components. The CTs are due to the cross-correlation of different path components. These CTs have no physical meaning and leads to an estimation error. We propose a new estimation method aiming to improve the estimation accuracy of the FCF of a band-limited transfer function. The basic idea behind the proposed method is to introduce a kernel function aiming to reduce the CT effect, while preserving the ATs. In this way, we can improve the estimation of the FCF. The performance of the proposed method and the frequency averaging technique is analyzed using a synthetically generated transfer function. We show that the proposed method is more accurate than the frequency averaging technique. The accurate estimation of the FCF is crucial for the system design. In fact, we can determine the coherence bandwidth from the FCF. The exact knowledge of the coherence bandwidth is beneficial in both the design as well as optimization of frequency interleaving and pilot arrangement schemes. © 2012 IEEE.

An improved method for estimating the frequency correlation function

KAUST Repository

Chelli, Ali

2012-04-01

For time-invariant frequency-selective channels, the transfer function is a superposition of waves having different propagation delays and path gains. In order to estimate the frequency correlation function (FCF) of such channels, the frequency averaging technique can be utilized. The obtained FCF can be expressed as a sum of auto-terms (ATs) and cross-terms (CTs). The ATs are caused by the autocorrelation of individual path components. The CTs are due to the cross-correlation of different path components. These CTs have no physical meaning and leads to an estimation error. We propose a new estimation method aiming to improve the estimation accuracy of the FCF of a band-limited transfer function. The basic idea behind the proposed method is to introduce a kernel function aiming to reduce the CT effect, while preserving the ATs. In this way, we can improve the estimation of the FCF. The performance of the proposed method and the frequency averaging technique is analyzed using a synthetically generated transfer function. We show that the proposed method is more accurate than the frequency averaging technique. The accurate estimation of the FCF is crucial for the system design. In fact, we can determine the coherence bandwidth from the FCF. The exact knowledge of the coherence bandwidth is beneficial in both the design as well as optimization of frequency interleaving and pilot arrangement schemes. © 2012 IEEE.

Pion correlations as a function of atomic mass in heavy ion collisions

International Nuclear Information System (INIS)

Chacon, A.D.

1989-01-01

The method of two pion interferometry was used to obtain source-size and lifetime parameters for the pions produced in heavy ion collisions. The systems used were 1.70 · A GeV 56 Fe + Fe, 1.82 · A GeV 40 Ar + KCl and 1.54 · A GeV 93 Nb + Nb, allowing for a search for dependences on the atomic number. Two acceptances (centered, in the lab., at ∼ 0 degrees and 45 degrees) were used for each system, allowing a search for dependences on the viewing angle. The correlation functions were calculated by comparing the data samples to background (or reference) samples made using the method of event mixing, where pions from different events are combined to produce a data sample in which the Bose-Einstein correlation effect is absent. The effect of the correlation function on the background samples is calculated, and a method for weighting the events to remove the residual correlation effect is presented. The effect of the spectrometer design on the measured correlation functions is discussed, as are methods for correcting for these effects during the data analysis. 58 refs., 39 figs., 18 tabs

СREATION OF CORRELATION FUNCTIONS OF LINEAR CONTINUOUS SYSTEMS BASED ON THEIR FUNDAMENTAL MATRICES

Directory of Open Access Journals (Sweden)

N. A. Vunder

2015-11-01

Full Text Available The paper presents a method of creating correlation matrices and functions of the state vectors and outputs of the linear continuous systems functioning under the conditions of stochastic stationary, in a broad sense, effects. Fundamental matrices form the basis of the method. We have shown that for the linear continuous systems with single dimensional input and single dimensional output the correlation output function of such system can be found as the free movement of this system generated by its initial state. This state is constructed from the variance matrix of the state vector and the transposed output matrix. We have elucidated that when a continuous system belongs to a class of multi-dimensional input – multi-dimensional output systems, the following options are available for solving the problem of creation of the correlation function of a linear system. The first option is to partition the system into separate channels. Then the approach developed for systems with onedimensional input and one-dimensional output is applied to each of the separate channels. The second option is used to preserve the vector nature of the stochastic external influence. It consists in partition of output vector to scalar components by separating output matrix into separate rows with subsequent formation of the correlation function according to the scheme for single dimensional input and single dimensional output type systems. The third option is based on the scalarization of matrix correlation output function by applying the singular value decomposition to it. That gives the possibility to form scalar majorant and minorant of correlation output functions. We have established that a key component of a computational procedure of creating the correlation function of continuous linear system is a variance matrix of the system state vector. In the case of functioning under an exogenous stochastic effect like "white noise" the variance matrix is calculated by

Adaptive endpoint detection of seismic signal based on auto-correlated function

International Nuclear Information System (INIS)

Fan Wanchun; Shi Ren

2000-01-01

There are certain shortcomings for the endpoint detection by time-waveform envelope and/or by checking the travel table (both labelled as the artificial detection method). Based on the analysis of the auto-correlation function, the notion of the distance between auto-correlation functions was quoted, and the characterizations of the noise and the signal with noise were discussed by using the distance. Then, the method of auto-adaptable endpoint detection of seismic signal based on auto-correlated similarity was summed up. The steps of implementation and determining of the thresholds were presented in detail. The experimental results that were compared with the methods based on artificial detecting show that this method has higher sensitivity even in a low SNR circumstance

Limited Awareness of the Essences of Certification or Compliance Markings on Medical Devices.

Science.gov (United States)

Foo, Jong Yong Abdiel; Tan, Xin Ji Alan

2017-06-01

Medical devices have been long used for odiagnostic, therapeutic or rehabilitation purposes. Currently, they can range from a low-cost portable device that is often used for personal health monitoring to high-end sophisticated equipment that can only be operated by trained professionals. Depending on the functional purposes, there are different certification or compliance markings on the device when it is sold. One common certification marking is the Conformité Européenne affixation but this has a range of certification mark numbering for a variety of functional purposes. While the regulators and medical device manufacturers understand the associated significance and clinical implications, these may not be apparent to the professionals (using or maintaining the device) and the general public. With portable healthcare devices and mobile applications gaining popularity, better awareness of certification marking will be needed. Particularly, there are differences in the allowed functional purposes and the associated cost derivations of devices with a seemingly similar nature. A preferred approach such as an easy-to-understand notation next to any certification marking on a device can aid in differentiation without the need to digest mountainous regulatory details.

Reduced Rank Mixed Effects Models for Spatially Correlated Hierarchical Functional Data

KAUST Repository

Zhou, Lan

2010-03-01

Hierarchical functional data are widely seen in complex studies where sub-units are nested within units, which in turn are nested within treatment groups. We propose a general framework of functional mixed effects model for such data: within unit and within sub-unit variations are modeled through two separate sets of principal components; the sub-unit level functions are allowed to be correlated. Penalized splines are used to model both the mean functions and the principal components functions, where roughness penalties are used to regularize the spline fit. An EM algorithm is developed to fit the model, while the specific covariance structure of the model is utilized for computational efficiency to avoid storage and inversion of large matrices. Our dimension reduction with principal components provides an effective solution to the difficult tasks of modeling the covariance kernel of a random function and modeling the correlation between functions. The proposed methodology is illustrated using simulations and an empirical data set from a colon carcinogenesis study. Supplemental materials are available online.

Correlation Function Approach for Estimating Thermal Conductivity in Highly Porous Fibrous Materials

Science.gov (United States)

Martinez-Garcia, Jorge; Braginsky, Leonid; Shklover, Valery; Lawson, John W.

2011-01-01

Heat transport in highly porous fiber networks is analyzed via two-point correlation functions. Fibers are assumed to be long and thin to allow a large number of crossing points per fiber. The network is characterized by three parameters: the fiber aspect ratio, the porosity and the anisotropy of the structure. We show that the effective thermal conductivity of the system can be estimated from knowledge of the porosity and the correlation lengths of the correlation functions obtained from a fiber structure image. As an application, the effects of the fiber aspect ratio and the network anisotropy on the thermal conductivity is studied.

Quark correlation functions in deep-inelastic semi-inclusive processes

International Nuclear Information System (INIS)

Levelt, J.; Mulders, P.J.

1994-01-01

We investigate one-particle semi-inclusive processes in lepton-hadron scattering. In unpolarized scattering order Q -1 corrections appear only when transverse momenta are detected. We consider the twist-two and -three matrix elements and calculate the semi-inclusive structure functions in terms of quark correlation functions. We find that at the twist-three level not only the standard quark distribution and fragmentation function contribute, but also two new transverse ''profile functions.'' We discuss the gauge invariance of the hadronic tensor at the twist-three level. The results of our approach are used to calculate expressions for some cross sections for semi-inclusive processes

The pair correlation function of spatial Hawkes processes

DEFF Research Database (Denmark)

Møller, Jesper; Torrisi, Giovanni Luca

2007-01-01

Spatial Hawkes processes can be considered as spatial versions of classical Hawkes processes. We derive the pair correlation function of stationary spatial Hawkes processes and discuss the connection to the Bartlett spectrum and other summary statistics. Particularly, results for Gaussian fertility...... rates and the extension to spatial Hawkes processes with random fertility rates are discussed....

Mean density and two-point correlation function for the CfA redshift survey slices

International Nuclear Information System (INIS)

De Lapparent, V.; Geller, M.J.; Huchra, J.P.

1988-01-01

The effect of large-scale inhomogeneities on the determination of the mean number density and the two-point spatial correlation function were investigated for two complete slices of the extension of the Center for Astrophysics (CfA) redshift survey (de Lapparent et al., 1986). It was found that the mean galaxy number density for the two strips is uncertain by 25 percent, more so than previously estimated. The large uncertainty in the mean density introduces substantial uncertainty in the determination of the two-point correlation function, particularly at large scale; thus, for the 12-deg slice of the CfA redshift survey, the amplitude of the correlation function at intermediate scales is uncertain by a factor of 2. The large uncertainties in the correlation functions might reflect the lack of a fair sample. 45 references

Neural correlates of the LSD experience revealed by multimodal neuroimaging.

Science.gov (United States)

Carhart-Harris, Robin L; Muthukumaraswamy, Suresh; Roseman, Leor; Kaelen, Mendel; Droog, Wouter; Murphy, Kevin; Tagliazucchi, Enzo; Schenberg, Eduardo E; Nest, Timothy; Orban, Csaba; Leech, Robert; Williams, Luke T; Williams, Tim M; Bolstridge, Mark; Sessa, Ben; McGonigle, John; Sereno, Martin I; Nichols, David; Hellyer, Peter J; Hobden, Peter; Evans, John; Singh, Krish D; Wise, Richard G; Curran, H Valerie; Feilding, Amanda; Nutt, David J

2016-04-26

Lysergic acid diethylamide (LSD) is the prototypical psychedelic drug, but its effects on the human brain have never been studied before with modern neuroimaging. Here, three complementary neuroimaging techniques: arterial spin labeling (ASL), blood oxygen level-dependent (BOLD) measures, and magnetoencephalography (MEG), implemented during resting state conditions, revealed marked changes in brain activity after LSD that correlated strongly with its characteristic psychological effects. Increased visual cortex cerebral blood flow (CBF), decreased visual cortex alpha power, and a greatly expanded primary visual cortex (V1) functional connectivity profile correlated strongly with ratings of visual hallucinations, implying that intrinsic brain activity exerts greater influence on visual processing in the psychedelic state, thereby defining its hallucinatory quality. LSD's marked effects on the visual cortex did not significantly correlate with the drug's other characteristic effects on consciousness, however. Rather, decreased connectivity between the parahippocampus and retrosplenial cortex (RSC) correlated strongly with ratings of "ego-dissolution" and "altered meaning," implying the importance of this particular circuit for the maintenance of "self" or "ego" and its processing of "meaning." Strong relationships were also found between the different imaging metrics, enabling firmer inferences to be made about their functional significance. This uniquely comprehensive examination of the LSD state represents an important advance in scientific research with psychedelic drugs at a time of growing interest in their scientific and therapeutic value. The present results contribute important new insights into the characteristic hallucinatory and consciousness-altering properties of psychedelics that inform on how they can model certain pathological states and potentially treat others.

Cosmological forecasts from photometric measurements of the angular correlation function

International Nuclear Information System (INIS)

Sobreira, F.; Rosenfeld, R.; Simoni, F. de; Costa, L. A. N. da; Maia, M. A. G.; Makler, M.

2011-01-01

We study forecasts for the accuracy of the determination of cosmological parameters from future large-scale photometric surveys obtained using the full shape of the 2-point galaxy angular correlation function. The effects of linear redshift-space distortion, photometric redshift Gaussian errors, galaxy bias and nonlinearities in the power spectrum are included on our analysis. The Fisher information matrix is constructed with the full covariance matrix, including the correlation between nearby redshift shells arising from the photometric redshift error. We show that under some reasonable assumptions, a survey such as the imminent Dark Energy Survey should be able to constrain the dark energy equation of state parameter w and the cold dark matter density Ω cdm with a precision of the order of 20% and 13%, respectively, from the full shape of the angular correlation function alone. When combined with priors from other observations the precision in the determination of these parameters improve to 8% and 4%, respectively.

Spatially heterogeneous dynamics investigated via a time-dependent four-point density correlation function

DEFF Research Database (Denmark)

Lacevic, N.; Starr, F. W.; Schrøder, Thomas

2003-01-01

correlation function g4(r,t) and corresponding "structure factor" S4(q,t) which measure the spatial correlations between the local liquid density at two points in space, each at two different times, and so are sensitive to dynamical heterogeneity. We study g4(r,t) and S4(q,t) via molecular dynamics......Relaxation in supercooled liquids above their glass transition and below the onset temperature of "slow" dynamics involves the correlated motion of neighboring particles. This correlated motion results in the appearance of spatially heterogeneous dynamics or "dynamical heterogeneity." Traditional...... two-point time-dependent density correlation functions, while providing information about the transient "caging" of particles on cooling, are unable to provide sufficiently detailed information about correlated motion and dynamical heterogeneity. Here, we study a four-point, time-dependent density...

Time correlation functions and transport coefficients in a dilute superfluid

International Nuclear Information System (INIS)

Kirkpatrick, T.R.; Dorfman, J.R.

1985-01-01

Time correlation functions for the transport coefficients in the linear Landau-Khalatnikov equations are derived on the basis of a formal theory. These Green--Kubo expressions are then explicitly evaluated for a dilute superfluid and the resulting transport coefficiencts are shown to be identical to those obtained previously by using a distribution function method

White-matter changes correlate with cognitive functioning in Parkinson's disease

Directory of Open Access Journals (Sweden)

Rebecca J Theilmann

2013-04-01

Full Text Available Diffusion tensor imaging (DTI findings from emerging studies of cortical white-matter integrity in Parkinson’s disease (PD without dementia are inconclusive. When white-matter changes have been found, their relationship to cognitive functioning in PD has not been carefully investigated. To better characterize changes in tissue diffusivity and to understand their functional significance, the present study conducted DTI in 25 PD patients without dementia and 26 controls of similar ages. An automated tract-based DTI method was used. Fractional anisotropy (FA, mean diffusivity (MD, axial diffusivity (AD, and radial diffusivity (RD were analyzed. Neuropsychological measures of executive functioning (working memory, verbal fluency, cognitive flexibility, inhibitory control and visuospatial ability were then correlated with regions of interest that showed abnormal diffusivity in the PD group. We found widespread reductions in FA and increases in MD in the PD group relative to controls. These changes were predominantly related to an increase in RD. Increased AD in the PD group was limited to specific frontal tracks of the right hemisphere, possibly signifying more significant tissue changes. Motor-symptom severity did not correlate with FA. However, different measures of executive functioning and visuospatial ability correlated with FA in different segments of tracts, which contain fiber pathways to cortical regions that are thought to support specific cognitive processes. The findings suggest that abnormal tissue diffusivity may be sensitive to subtle cognitive changes in PD, some of which may be prognostic of future cognitive decline.

Correlation measurements of sodium flow rate with magnetic sensors

International Nuclear Information System (INIS)

Kebadze, B.V.; Krasnoyarov, N.V.; Adamovskij, L.A.; Golushko, V.V.; Sroelov, V.S.

1978-01-01

The results of bench-mark experiments and those carried out at the BOR-60 reactor to measure the sodium coolant flow rate by a correlation method are presented. The method is based on detecting the eddy type flow hydraulic nonuniformities using magnetic flowmeters. The measurements were fulfilled in a broad range of flow rates (G=10-10 4 m 3 /h, Re=2x10 5 -2x10 7 ). The measured and calculated mutual correlation functions are presented with parallel and perpendicular orientations of the flowmeters magnetic fields. A good accord is stated. Prerequirements to the arrangement of the measuring systems are formulated. As an important advantage of the correlation method a possibility of the flowmeter calibration in situ is hydhlighted

Fish functional traits correlated with environmental variables in a temperate biodiversity hotspot.

Directory of Open Access Journals (Sweden)

Benjamin P Keck

Full Text Available The global biodiversity crisis has invigorated the search for generalized patterns in most disciplines within the natural sciences. Studies based on organismal functional traits attempt to broaden implications of results by identifying the response of functional traits, instead of taxonomic units, to environmental variables. Determining the functional trait responses enables more direct comparisons with, or predictions for, communities of different taxonomic composition. The North American freshwater fish fauna is both diverse and increasingly imperiled through human mediated disturbances, including climate change. The Tennessee River, USA, contains one of the most diverse assemblages of freshwater fish in North America and has more imperiled species than other rivers, but there has been no trait-based study of community structure in the system. We identified 211 localities in the upper Tennessee River that were sampled by the Tennessee Valley Authority between 2009 and 2011 and compiled fish functional traits for the observed species and environmental variables for each locality. Using fourth corner analysis, we identified significant correlations between many fish functional traits and environmental variables. Functional traits associated with an opportunistic life history strategy were correlated with localities subject to greater land use disturbance and less flow regulation, while functional traits associated with a periodic life history strategy were correlated with localities subject to regular disturbance and regulated flow. These are patterns observed at the continental scale, highlighting the generalizability of trait-based methods. Contrary to studies that found no community structure differences when considering riparian buffer zones, we found that fish functional traits were correlated with different environmental variables between analyses with buffer zones vs. entire catchment area land cover proportions. Using existing databases

Fish functional traits correlated with environmental variables in a temperate biodiversity hotspot.

Science.gov (United States)

Keck, Benjamin P; Marion, Zachary H; Martin, Derek J; Kaufman, Jason C; Harden, Carol P; Schwartz, John S; Strange, Richard J

2014-01-01

The global biodiversity crisis has invigorated the search for generalized patterns in most disciplines within the natural sciences. Studies based on organismal functional traits attempt to broaden implications of results by identifying the response of functional traits, instead of taxonomic units, to environmental variables. Determining the functional trait responses enables more direct comparisons with, or predictions for, communities of different taxonomic composition. The North American freshwater fish fauna is both diverse and increasingly imperiled through human mediated disturbances, including climate change. The Tennessee River, USA, contains one of the most diverse assemblages of freshwater fish in North America and has more imperiled species than other rivers, but there has been no trait-based study of community structure in the system. We identified 211 localities in the upper Tennessee River that were sampled by the Tennessee Valley Authority between 2009 and 2011 and compiled fish functional traits for the observed species and environmental variables for each locality. Using fourth corner analysis, we identified significant correlations between many fish functional traits and environmental variables. Functional traits associated with an opportunistic life history strategy were correlated with localities subject to greater land use disturbance and less flow regulation, while functional traits associated with a periodic life history strategy were correlated with localities subject to regular disturbance and regulated flow. These are patterns observed at the continental scale, highlighting the generalizability of trait-based methods. Contrary to studies that found no community structure differences when considering riparian buffer zones, we found that fish functional traits were correlated with different environmental variables between analyses with buffer zones vs. entire catchment area land cover proportions. Using existing databases and fourth corner

Correlated wave functions for three-particle systems with Coulomb interaction - The muonic helium atom

Science.gov (United States)

Huang, K.-N.

1977-01-01

A computational procedure for calculating correlated wave functions is proposed for three-particle systems interacting through Coulomb forces. Calculations are carried out for the muonic helium atom. Variational wave functions which explicitly contain interparticle coordinates are presented for the ground and excited states. General Hylleraas-type trial functions are used as the basis for the correlated wave functions. Excited-state energies of the muonic helium atom computed from 1- and 35-term wave functions are listed for four states.

Mark Tompkins Canaccord

OpenAIRE

Mark Tompkins Canaccord

2018-01-01

Mark Tompkins Canaccord is a senior technologist for ecosystem and water resources management in SEC SAID Oakland, California office. In his career which lasts over fifteen years Mark has worked on project involving lake restorations, clean water engineering, ecological engineering and management, hydrology, hydraulics, sediment transport and other projects for environmental planning all over the country. Mark Tompkins Canaccord tries to blend his skills of planning and engineering with s...

Reconfiguring trade mark law

DEFF Research Database (Denmark)

Elsmore, Matthew James

2013-01-01

-border setting, with a particular focus on small business and consumers. The article's overall message is to call for a rethink of received wisdom suggesting that trade marks are effective trade-enabling devices. The case is made for reassessing how we think about European trade mark law.......First, this article argues that trade mark law should be approached in a supplementary way, called reconfiguration. Second, the article investigates such a reconfiguration of trade mark law by exploring the interplay of trade marks and service transactions in the Single Market, in the cross...

The role of three-gluon correlation functions in the single spin asymmetry

Directory of Open Access Journals (Sweden)

Beppu Hiroo

2015-01-01

Full Text Available We study the twist-3 three-gluon contribution to the single spin asymmetry in the light-hadron production in pp collision in the framework of the collinear factorization. We derive the corresponding cross section formula in the leading order with respect to the QCD coupling constant. We also present a numerical calculation of the asymmetry at the RHIC energy, using a model for the three-gluon correlation functions suggested by the asymmetry for the D-meson production at RHIC. We found that the asymmetries for the light-hadron and the jet productions are very useful to constrain the magnitude and form of the correlation functions. Since the three-gluon correlation functions shift the asymmetry for all kinds of hadrons in the same direction, it is unlikely that they become a main source of the asymmetry.

Applying a uniform marked morphism to a word

Directory of Open Access Journals (Sweden)

Anna Frid

1999-12-01

Full Text Available We describe the relationship between different parameters of the initial word and its image obtained by application of a uniform marked morphism. The functions described include the subword complexity, frequency of factors, and the recurrence function. The relations obtained for the image of a word can be used also for the image of a factorial language. Using induction, we give a full description of the involved functions of the fixed point of the morphism considered.

Inhomogeneity induced and appropriately parameterized semilocal exchange and correlation energy functionals in two-dimensions

Science.gov (United States)

Patra, Abhilash; Jana, Subrata; Samal, Prasanjit

2018-04-01

The construction of meta generalized gradient approximations based on the density matrix expansion (DME) is considered as one of the most accurate techniques to design semilocal exchange energy functionals in two-dimensional density functional formalism. The exchange holes modeled using DME possess unique features that make it a superior entity. Parameterized semilocal exchange energy functionals based on the DME are proposed. The use of different forms of the momentum and flexible parameters is to subsume the non-uniform effects of the density in the newly constructed semilocal functionals. In addition to the exchange functionals, a suitable correlation functional is also constructed by working upon the local correlation functional developed for 2D homogeneous electron gas. The non-local effects are induced into the correlation functional by a parametric form of one of the newly constructed exchange energy functionals. The proposed functionals are applied to the parabolic quantum dots with a varying number of confined electrons and the confinement strength. The results obtained with the aforementioned functionals are quite satisfactory, which indicates why these are suitable for two-dimensional quantum systems.

Signals of dynamical and statistical process from IMF-IMF correlation function

Science.gov (United States)

Pagano, E. V.; Acosta, L.; Auditore, L.; Baran, V.; Cap, T.; Cardella, G.; Colonna, M.; De Luca, S.; De Filippo, E.; Dell'Aquila, D.; Francalanza, L.; Gnoffo, B.; Lanzalone, G.; Lombardo, I.; Maiolino, C.; Martorana, N. S.; Norella, S.; Pagano, A.; Papa, M.; Piasecki, E.; Pirrone, S.; Politi, G.; Porto, F.; Quattrocchi, L.; Rizzo, F.; Rosato, E.; Russotto, P.; Siwek-Wilczyńska, K.; Trifiro, A.; Trimarchi, M.; Verde, G.; Vigilante, M.; Wilczyńsky, J.

2017-11-01

In this paper we briefly discuss about a novel application of the IMF-IMF correlation function to the physical case of binary massive projectile-like (PLF) splitting for dynamical and statistical breakup/fission in heavy ion collisions at Fermi energy. Theoretical simulations are also shown for comparisons with the data. These preliminary results have been obtained for the reverse kinematics reaction 124Sn + 64Ni at 35 AMeV that was studied using the forward part of CHIMERA detector. In that reaction a strong competition between a dynamical and a statistical components and its evolution with the charge asymmetry of the binary break up was already shown. In this work we show that the IMF-IMF correlation function can be used to pin down the timescale of the fragments production in binary fission-like phenomena. We also made simulations with the CoMDII model in order to compare to the experimental IMF-IMF correlation function. In future we plan to extend these studies to different reaction mechanisms and nuclear systems and to compare with different theoretical transport simulations.

Gauge-fixing parameter dependence of two-point gauge-variant correlation functions

International Nuclear Information System (INIS)

Zhai, C.

1996-01-01

The gauge-fixing parameter ξ dependence of two-point gauge-variant correlation functions is studied for QED and QCD. We show that, in three Euclidean dimensions, or for four-dimensional thermal gauge theories, the usual procedure of getting a general covariant gauge-fixing term by averaging over a class of covariant gauge-fixing conditions leads to a nontrivial gauge-fixing parameter dependence in gauge-variant two-point correlation functions (e.g., fermion propagators). This nontrivial gauge-fixing parameter dependence modifies the large-distance behavior of the two-point correlation functions by introducing additional exponentially decaying factors. These factors are the origin of the gauge dependence encountered in some perturbative evaluations of the damping rates and the static chromoelectric screening length in a general covariant gauge. To avoid this modification of the long-distance behavior introduced by performing the average over a class of covariant gauge-fixing conditions, one can either choose a vanishing gauge-fixing parameter or apply an unphysical infrared cutoff. copyright 1996 The American Physical Society

Heavy particle signatures in cosmological correlation functions with tensor modes

Science.gov (United States)

Saito, Ryo; Kubota, Takahiro

2018-06-01

We explore the possibility to make use of cosmological data to look for signatures of unknown heavy particles whose masses are on the order of the Hubble parameter during the time of inflation. To be more specific we take up the quasi-single field inflation model, in which the isocurvaton σ is supposed to be the heavy particle. We study correlation functions involving both scalar (ζ ) and tensor (γ ) perturbations and search for imprints of the σ-particle effects. We make use of the technique of the effective field theory for inflation to derive the ζ σ and γ ζ σ couplings. With these couplings we compute the effects due to σ to the power spectrum langle ζ ζ rangle and correlations langle γs ζ ζ rangle and langle γs1 γ s2 ζ ζ rangle , where s, s1 and s2 are the polarization indices of gravitons. Numerical analyses of the σ-mass effects to these correlations are presented. It is argued that future precise observations of these correlations could make it possible to measure the σ-mass and the strength of the ζ σ and γ ζ σ couplings. As an extension to the N-graviton case we also compute the correlations langle γ s1 ... γ sN ζ ζ rangle and langle γ s1 ... ... γ s2N ζ ζ rangle and their σ-mass effects. It is suggested that larger N correlation functions are useful to probe larger σ-mass.

Superaging correlation function and ergodicity breaking for Brownian motion in logarithmic potentials.

Science.gov (United States)

Dechant, A; Lutz, E; Kessler, D A; Barkai, E

2012-05-01

We consider an overdamped Brownian particle moving in a confining asymptotically logarithmic potential, which supports a normalized Boltzmann equilibrium density. We derive analytical expressions for the two-time correlation function and the fluctuations of the time-averaged position of the particle for large but finite times. We characterize the occurrence of aging and nonergodic behavior as a function of the depth of the potential, and we support our predictions with extensive Langevin simulations. While the Boltzmann measure is used to obtain stationary correlation functions, we show how the non-normalizable infinite covariant density is related to the superaging behavior.

Statistical Study of Turbulence: Spectral Functions and Correlation Coefficients

Science.gov (United States)

Frenkiel, Francois N.

1958-01-01

In reading the publications on turbulence of different authors, one often runs the risk of confusing the various correlation coefficients and turbulence spectra. We have made a point of defining, by appropriate concepts, the differences which exist between these functions. Besides, we introduce in the symbols a few new characteristics of turbulence. In the first chapter, we study some relations between the correlation coefficients and the different turbulence spectra. Certain relations are given by means of demonstrations which could be called intuitive rather than mathematical. In this way we demonstrate that the correlation coefficients between the simultaneous turbulent velocities at two points are identical, whether studied in Lagrange's or in Euler's systems. We then consider new spectra of turbulence, obtained by study of the simultaneous velocities along a straight line of given direction. We determine some relations between these spectra and the correlation coefficients. Examining the relation between the spectrum of the turbulence measured at a fixed point and the longitudinal-correlation curve given by G. I. Taylor, we find that this equation is exact only when the coefficient is very small.

Core Noise Diagnostics of Turbofan Engine Noise Using Correlation and Coherence Functions

Science.gov (United States)

Miles, Jeffrey H.

2009-01-01

Cross-correlation and coherence functions are used to look for periodic acoustic components in turbofan engine combustor time histories, to investigate direct and indirect combustion noise source separation based on signal propagation time delays, and to provide information on combustor acoustics. Using the cross-correlation function, time delays were identified in all cases, clearly indicating the combustor is the source of the noise. In addition, unfiltered and low-pass filtered at 400 Hz signals had a cross-correlation time delay near 90 ms, while the low-pass filtered at less than 400 Hz signals had a cross-correlation time delay longer than 90 ms. Low-pass filtering at frequencies less than 400 Hz partially removes the direct combustion noise signals. The remainder includes the indirect combustion noise signal, which travels more slowly because of the dependence on the entropy convection velocity in the combustor. Source separation of direct and indirect combustion noise is demonstrated by proper use of low-pass filters with the cross-correlation function for a range of operating conditions. The results may lead to a better idea about the acoustics in the combustor and may help develop and validate improved reduced-order physics-based methods for predicting direct and indirect combustion noise.

A two-point correlation function for Galactic halo stars

NARCIS (Netherlands)

Cooper, A. P.; Cole, S.; Frenk, C. S.; Helmi, A.

2011-01-01

We describe a correlation function statistic that quantifies the amount of spatial and kinematic substructure in the stellar halo. We test this statistic using model stellar halo realizations constructed from the Aquarius suite of six high-resolution cosmological N-body simulations, in combination

Exchange-correlation energies of atoms from efficient density functionals: influence of the electron density

Science.gov (United States)

Tao, Jianmin; Ye, Lin-Hui; Duan, Yuhua

2017-12-01

The primary goal of Kohn-Sham density functional theory is to evaluate the exchange-correlation contribution to electronic properties. However, the accuracy of a density functional can be affected by the electron density. Here we apply the nonempirical Tao-Mo (TM) semilocal functional to study the influence of the electron density on the exchange and correlation energies of atoms and ions, and compare the results with the commonly used nonempirical semilocal functionals local spin-density approximation (LSDA), Perdew-Burke-Ernzerhof (PBE), Tao-Perdew-Staroverov-Scuseria (TPSS), and hybrid functional PBE0. We find that the spin-restricted Hartree-Fock density yields the exchange and correlation energies in good agreement with the Optimized Effective Potential method, particularly for spherical atoms and ions. However, the errors of these semilocal and hybrid functionals become larger for self-consistent densities. We further find that the quality of the electron density have greater effect on the exchange-correlation energies of kinetic energy density-dependent meta-GGA functionals TPSS and TM than on those of the LSDA and GGA, and therefore, should have greater influence on the performance of meta-GGA functionals. Finally, we show that the influence of the density quality on PBE0 is slightly reduced, compared to that of PBE, due to the exact mixing.

Describing a Strongly Correlated Model System with Density Functional Theory.

Science.gov (United States)

Kong, Jing; Proynov, Emil; Yu, Jianguo; Pachter, Ruth

2017-07-06

The linear chain of hydrogen atoms, a basic prototype for the transition from a metal to Mott insulator, is studied with a recent density functional theory model functional for nondynamic and strong correlation. The computed cohesive energy curve for the transition agrees well with accurate literature results. The variation of the electronic structure in this transition is characterized with a density functional descriptor that yields the atomic population of effectively localized electrons. These new methods are also applied to the study of the Peierls dimerization of the stretched even-spaced Mott insulator to a chain of H 2 molecules, a different insulator. The transitions among the two insulating states and the metallic state of the hydrogen chain system are depicted in a semiquantitative phase diagram. Overall, we demonstrate the capability of studying strongly correlated materials with a mean-field model at the fundamental level, in contrast to the general pessimistic view on such a feasibility.

Gluon 2- and 3-Point Correlation Functions on the Lattice

OpenAIRE

Parrinello, Claudio

1993-01-01

I present some preliminary results, obtained in collaboration with C. Bernard and A. Soni, for the lattice evaluation of 2- and 3-point gluon correlation functions in momentum space, with emphasis on the amputated 3-gluon vertex function. The final goal of this approach is the study of the running QCD coupling constant as defined from the amputated 3-gluon vertex.

2- and 3-point gluon correlation functions on the lattice

Energy Technology Data Exchange (ETDEWEB)

Parrinello, C. (Dept. of Physics, Univ. of Edinburgh (United Kingdom))

1994-04-01

I present some preliminary results, obtained in collaboration with C. Bernard and A. Soni, for the lattice evaluation of 2- and 3-point gluon correlation functions in momentum space, with emphasis on the amputated 3-gluon vertex function. The final goal of this approach is the study of the running QCD coupling constant as defined from the amputated 3-gluon vertex. (orig.)

BWR Mark I pressure suppression study: bench mark experiments

International Nuclear Information System (INIS)

Lai, W.; McCauley, E.W.

1977-01-01

Computer simulations representative of the wetwell of Mark I BWR's have predicted pressures and related phenomena. However, calculational predictions for purposes of engineering decision will be possible only if the code can be verified, i.e., shown to compute in accord with measured values. Described in the report is a set of single downcomer spherical flask bench mark experiments designed to produce quantitative data to validate various air-water dynamic computations; the experiments were performed since relevant bench mark data were not available from outside sources. Secondary purposes of the study were to provide a test bed for the instrumentation and post-experiment data processing techniques to be used in the Laboratory's reactor safety research program and to provide additional masurements for the air-water scaling study

Elemental marking of arthropod pests in agricultural systems: single and multigenerational marking

Science.gov (United States)

Jane Leslie Hayes

1991-01-01

Use of elemental markers to study movement of arthropod pests of field crops is reviewed. Trace elements, rubidium (Rb) and cesium (Cs), have provided a nondisruptive method of marking natural adult populations via developmental stage consumption of treated host plants. Multigenerational marking occurs with the transfer of elemental markers from marked adults to...

Importance of the correlation contribution for local hybrid functionals: range separation and self-interaction corrections.

Science.gov (United States)

Arbuznikov, Alexei V; Kaupp, Martin

2012-01-07

Local hybrid functionals with their position-dependent exact-exchange admixture are a conceptually simple and promising extension of the concept of a hybrid functional. Local hybrids based on a simple mixing of the local spin density approximation (LSDA) with exact exchange have been shown to be successful for thermochemistry, reaction barriers, and a range of other properties. So far, the combination of this generation of local hybrids with an LSDA correlation functional has been found to give the most favorable results for atomization energies, for a range of local mixing functions (LMFs) governing the exact-exchange admixture. Here, we show that the choice of correlation functional to be used with local hybrid exchange crucially influences the parameterization also of the exchange part as well as the overall performance. A novel ansatz for the correlation part of local hybrids is suggested based on (i) range-separation of LSDA correlation into short-range (SR) and long-range (LR) parts, and (ii) partial or full elimination of the one-electron self-correlation from the SR part. It is shown that such modified correlation functionals allow overall larger exact exchange admixture in thermochemically competitive local hybrids than before. This results in improvements for reaction barriers and for other properties crucially influenced by self-interaction errors, as demonstrated by a number of examples. Based on the range-separation approach, a fresh view on the breakdown of the correlation energy into dynamical and non-dynamical parts is suggested.

ULTOR(Registered TradeMark) Passive Pose and Position Engine For Spacecraft Relative Navigation

Science.gov (United States)

Hannah, S. Joel

2008-01-01

The ULTOR(Registered TradeMark) Passive Pose and Position Engine (P3E) technology, developed by Advanced Optical Systems, Inc (AOS), uses real-time image correlation to provide relative position and pose data for spacecraft guidance, navigation, and control. Potential data sources include a wide variety of sensors, including visible and infrared cameras. ULTOR(Registered TradeMark) P3E has been demonstrated on a number of host processing platforms. NASA is integrating ULTOR(Registerd TradeMark) P3E into its Relative Navigation System (RNS), which is being developed for the upcoming Hubble Space Telescope (HST) Servicing Mission 4 (SM4). During SM4 ULTOR(Registered TradeMark) P3E will perform realtime pose and position measurements during both the approach and departure phases of the mission. This paper describes the RNS implementation of ULTOR(Registered TradeMark) P3E, and presents results from NASA's hardware-in-the-loop simulation testing against the HST mockup.

Analytical expressions for the correlation function of a hard sphere dimer fluid

Science.gov (United States)

Kim, Soonho; Chang, Jaeeon; Kim, Hwayong

A closed form expression is given for the correlation function of a hard sphere dimer fluid. A set of integral equations is obtained from Wertheim's multidensity Ornstein-Zernike integral equation theory with Percus-Yevick approximation. Applying the Laplace transformation method to the integral equations and then solving the resulting equations algebraically, the Laplace transforms of the individual correlation functions are obtained. By the inverse Laplace transformation, the radial distribution function (RDF) is obtained in closed form out to 3D (D is the segment diameter). The analytical expression for the RDF of the hard dimer should be useful in developing the perturbation theory of dimer fluids.

Analytical expression for the correlation function of a hard sphere chain fluid

Science.gov (United States)

Chang, Jaeeon; Kim, Hwayong

A closed form expression is given for the correlation function of flexible hard sphere chain fluid. A set of integral equations obtained from Wertheim's multidensity Ornstein-Zernike integral equation theory with the polymer Percus-Yevick ideal chain approximation is considered. Applying the Laplace transformation method to the integral equations and then solving the resulting equations algebraically, the Laplace transforms of individual correlation functions are obtained. By inverse Laplace transformation the inter- and intramolecular radial distribution functions (RDFs) are obtained in closed forms up to 3D(D is segment diameter). These analytical expressions for the RDFs would be useful in developing the perturbation theory of chain fluids.

On form factors and correlation functions in twistor space

International Nuclear Information System (INIS)

Koster, Laura; Mitev, Vladimir; Staudacher, Matthias; Wilhelm, Matthias

2017-01-01

In this paper, we continue our study of form factors and correlation functions of gauge-invariant local composite operators in the twistor-space formulation of N=4 super Yang-Mills theory. Using the vertices for these operators obtained in our recent papers (DOI: 10.1103/PhysRevLett.117.011601; 10.1007/JHEP06(2016)162 ), we show how to calculate the twistor-space diagrams for general N k MHV form factors via the inverse soft limit, in analogy to the amplitude case. For general operators without α-dot indices, we then reexpress the NMHV form factors from the position-twistor calculation in terms of momentum twistors, deriving and expanding on a relation between the two twistor formalisms previously observed in the case of amplitudes. Furthermore, we discuss the calculation of generalized form factors and correlation functions as well as the extension to loop level, in particular providing an argument promised in https://www.doi.org/10.1002/prop.201400085.

Temporal correlation functions of concentration fluctuations: an anomalous case.

Science.gov (United States)

Lubelski, Ariel; Klafter, Joseph

2008-10-09

We calculate, within the framework of the continuous time random walk (CTRW) model, multiparticle temporal correlation functions of concentration fluctuations (CCF) in systems that display anomalous subdiffusion. The subdiffusion stems from the nonstationary nature of the CTRW waiting times, which also lead to aging and ergodicity breaking. Due to aging, a system of diffusing particles tends to slow down as time progresses, and therefore, the temporal correlation functions strongly depend on the initial time of measurement. As a consequence, time averages of the CCF differ from ensemble averages, displaying therefore ergodicity breaking. We provide a simple example that demonstrates the difference between these two averages, a difference that might be amenable to experimental tests. We focus on the case of ensemble averaging and assume that the preparation time of the system coincides with the starting time of the measurement. Our analytical calculations are supported by computer simulations based on the CTRW model.

On form factors and correlation functions in twistor space

Energy Technology Data Exchange (ETDEWEB)

Koster, Laura [Institut für Mathematik, Institut für Physik und IRIS Adlershof,Humboldt-Universität zu Berlin,Zum Großen Windkanal 6, 12489 Berlin (Germany); Mitev, Vladimir [PRISMA Cluster of Excellence, Institut für Physik, WA THEP,Johannes Gutenberg-Universität Mainz,Staudingerweg 7, 55128 Mainz (Germany); Staudacher, Matthias [Institut für Mathematik, Institut für Physik und IRIS Adlershof,Humboldt-Universität zu Berlin,Zum Großen Windkanal 6, 12489 Berlin (Germany); Wilhelm, Matthias [Niels Bohr Institute, Copenhagen University,Blegdamsvej 17, 2100 Copenhagen Ø (Denmark)

2017-03-24

In this paper, we continue our study of form factors and correlation functions of gauge-invariant local composite operators in the twistor-space formulation of N=4 super Yang-Mills theory. Using the vertices for these operators obtained in our recent papers (DOI: 10.1103/PhysRevLett.117.011601; 10.1007/JHEP06(2016)162 ), we show how to calculate the twistor-space diagrams for general N{sup k}MHV form factors via the inverse soft limit, in analogy to the amplitude case. For general operators without α-dot indices, we then reexpress the NMHV form factors from the position-twistor calculation in terms of momentum twistors, deriving and expanding on a relation between the two twistor formalisms previously observed in the case of amplitudes. Furthermore, we discuss the calculation of generalized form factors and correlation functions as well as the extension to loop level, in particular providing an argument promised in https://www.doi.org/10.1002/prop.201400085.

S-pairing in neutron matter: I. Correlated basis function theory

International Nuclear Information System (INIS)

Fabrocini, Adelchi; Fantoni, Stefano; Illarionov, Alexey Yu.; Schmidt, Kevin E.

2008-01-01

S-wave pairing in neutron matter is studied within an extension of correlated basis function (CBF) theory to include the strong, short range spatial correlations due to realistic nuclear forces and the pairing correlations of the Bardeen, Cooper and Schrieffer (BCS) approach. The correlation operator contains central as well as tensor components. The correlated BCS scheme of [S. Fantoni, Nucl. Phys. A 363 (1981) 381], developed for simple scalar correlations, is generalized to this more realistic case. The energy of the correlated pair condensed phase of neutron matter is evaluated at the two-body order of the cluster expansion, but considering the one-body density and the corresponding energy vertex corrections at the first order of the Power Series expansion. Based on these approximations, we have derived a system of Euler equations for the correlation factors and for the BCS amplitudes, resulting in correlated nonlinear gap equations, formally close to the standard BCS ones. These equations have been solved for the momentum independent part of several realistic potentials (Reid, Argonne v 14 and Argonne v 8 ' ) to stress the role of the tensor correlations and of the many-body effects. Simple Jastrow correlations and/or the lack of the density corrections enhance the gap with respect to uncorrelated BCS, whereas it is reduced according to the strength of the tensor interaction and following the inclusion of many-body contributions

Peculiarities of the momentum distribution functions of strongly correlated charged fermions

Science.gov (United States)

Larkin, A. S.; Filinov, V. S.; Fortov, V. E.

2018-01-01

New numerical version of the Wigner approach to quantum thermodynamics of strongly coupled systems of particles has been developed for extreme conditions, when analytical approximations based on different kinds of perturbation theories cannot be applied. An explicit analytical expression of the Wigner function has been obtained in linear and harmonic approximations. Fermi statistical effects are accounted for by effective pair pseudopotential depending on coordinates, momenta and degeneracy parameter of particles and taking into account Pauli blocking of fermions. A new quantum Monte-Carlo method for calculations of average values of arbitrary quantum operators has been developed. Calculations of the momentum distribution functions and the pair correlation functions of degenerate ideal Fermi gas have been carried out for testing the developed approach. Comparison of the obtained momentum distribution functions of strongly correlated Coulomb systems with the Maxwell-Boltzmann and the Fermi distributions shows the significant influence of interparticle interaction both at small momenta and in high energy quantum ‘tails’.

Non-Poisson Dichotomous Noise: Higher-Order Correlation Functions and Aging

National Research Council Canada - National Science Library

Allegrini, Paolo; Grigolini, Paolo; Palatella, Luigi; West, Bruce J

2004-01-01

.... The transition of psi(tau) from the exponential to the nonexponential condition yields the breakdown of the usual factorization condition of higher-order correlation functions, as well as the birth of aging effects...

Correlation between cognitive function, gross motor skills and health â

African Journals Online (AJOL)

Saly Said Abd El-Hady

... attention and concentration, learning, memory and language that can result in mild to profound ... adulthood and affect health related quality of life (HRQOL) and wellbeing in ... investigate the correlation between cognitive function; attention/-.

Correlation with liver scintigram, reticuloendothelial function test, plasma endotoxin level and liver function tests in chronic liver diseases. Multivariate analysis

Energy Technology Data Exchange (ETDEWEB)

Ohmoto, Kenji; Yamamoto, Shinichi; Ideguchi, Seiji and others

1989-02-01

Liver scintigrams with Tc-99m phytate were reviewed in a total of 64 consecutive patients, comprising 28 with chronic hepatitis and 36 with liver cirrhosis. Reticuloendothelial (RES) function, plasma endotoxin (Et) levels and findings of general liver function tests were used as reference parameters to determine the diagnostic ability of liver scintigraphy. Multivariate analyses revealed that liver scintigrams had a strong correlation with RES function and Et levels in terms of morphology of the liver and hepatic and bone marrow Tc-99m uptake. General liver function tests revealed gamma globulin to be correlated with hepatic uptake and the degree of splenogemaly on liver scintigrams; and ICG levels at 15 min to be correlated with bone marrow and splenic uptake. Accuracy of liver scintigraphy was 73% for chronic hepatitis, which was inferior to general liver function tests (83%). When both modalities were combined, diangostic accuracy increased to 95%. Liver scintigraphy seems to be useful as a complementary approach. (Namekawa, K).

Frequency and spatial correlation functions in a fading communication channel through the ionosphere

International Nuclear Information System (INIS)

Liu, C.H.; Yeh, K.C.

1975-01-01

Equations for the two-frequency two-position mutual coherence functions are derived under the usual parabolic and Markov approximations. These equations are then solved numerically. It is shown that the mutual coherence functions occur naturally in the study of pulse distortion through a random communication channel and in the investigation of signal correlations. Contour plots of correlation functions show the possibility of having equal values at two frequency separations for a given spatial separation. This behavior is explainable in terms of overlapping Fresnel zones

Analytic methods for the Percus-Yevick hard sphere correlation functions

Directory of Open Access Journals (Sweden)

D. Henderson

2009-01-01

Full Text Available The Percus-Yevick theory for hard spheres provides simple accurate expressions for the correlation functions that have proven exceptionally useful. A summary of the author's lecture notes concerning three methods of obtaining these functions are presented. These notes are original only in part. However, they contain some helpful steps and simplifications. The purpose of this paper is to make these notes more widely available.

Correlation Function Analysis of Fiber Networks: Implications for Thermal Conductivity

Science.gov (United States)

Martinez-Garcia, Jorge; Braginsky, Leonid; Shklover, Valery; Lawson, John W.

2011-01-01

The heat transport in highly porous fiber structures is investigated. The fibers are supposed to be thin, but long, so that the number of the inter-fiber connections along each fiber is large. We show that the effective conductivity of such structures can be found from the correlation length of the two-point correlation function of the local conductivities. Estimation of the parameters, determining the conductivity, from the 2D images of the structures is analyzed.

Derivative discontinuity and exchange-correlation potential of meta-GGAs in density-functional theory.

Science.gov (United States)

Eich, F G; Hellgren, Maria

2014-12-14

We investigate fundamental properties of meta-generalized-gradient approximations (meta-GGAs) to the exchange-correlation energy functional, which have an implicit density dependence via the Kohn-Sham kinetic-energy density. To this purpose, we construct the most simple meta-GGA by expressing the local exchange-correlation energy per particle as a function of a fictitious density, which is obtained by inverting the Thomas-Fermi kinetic-energy functional. This simple functional considerably improves the total energy of atoms as compared to the standard local density approximation. The corresponding exchange-correlation potentials are then determined exactly through a solution of the optimized effective potential equation. These potentials support an additional bound state and exhibit a derivative discontinuity at integer particle numbers. We further demonstrate that through the kinetic-energy density any meta-GGA incorporates a derivative discontinuity. However, we also find that for commonly used meta-GGAs the discontinuity is largely underestimated and in some cases even negative.

Derivative discontinuity and exchange-correlation potential of meta-GGAs in density-functional theory

International Nuclear Information System (INIS)

Eich, F. G.; Hellgren, Maria

2014-01-01

We investigate fundamental properties of meta-generalized-gradient approximations (meta-GGAs) to the exchange-correlation energy functional, which have an implicit density dependence via the Kohn-Sham kinetic-energy density. To this purpose, we construct the most simple meta-GGA by expressing the local exchange-correlation energy per particle as a function of a fictitious density, which is obtained by inverting the Thomas-Fermi kinetic-energy functional. This simple functional considerably improves the total energy of atoms as compared to the standard local density approximation. The corresponding exchange-correlation potentials are then determined exactly through a solution of the optimized effective potential equation. These potentials support an additional bound state and exhibit a derivative discontinuity at integer particle numbers. We further demonstrate that through the kinetic-energy density any meta-GGA incorporates a derivative discontinuity. However, we also find that for commonly used meta-GGAs the discontinuity is largely underestimated and in some cases even negative

Hidden symmetry of four-point correlation functions and amplitudes in N=4 SYM

CERN Document Server

Eden, Burkhard; Korchemsky, Gregory P; Sokatchev, Emery

2012-01-01

We study the four-point correlation function of stress-tensor supermultiplets in N=4 SYM using the method of Lagrangian insertions. We argue that, as a corollary of N=4 superconformal symmetry, the resulting all-loop integrand possesses an unexpected complete symmetry under the exchange of the four external and all the internal (integration) points. This alone allows us to predict the integrand of the three-loop correlation function up to four undetermined constants. Further, exploiting the conjectured amplitude/correlation function duality, we are able to fully determine the three-loop integrand in the planar limit. We perform an independent check of this result by verifying that it is consistent with the operator product expansion, in particular that it correctly reproduces the three-loop anomalous dimension of the Konishi operator. As a byproduct of our study, we also obtain the three-point function of two half-BPS operators and one Konishi operator at three-loop level. We use the same technique to work ou...

Within-Subject Correlation Analysis to Detect Functional Areas Associated With Response Inhibition

Directory of Open Access Journals (Sweden)

Tomoko Yamasaki

2018-05-01

Full Text Available Functional areas in fMRI studies are often detected by brain-behavior correlation, calculating across-subject correlation between the behavioral index and the brain activity related to a function of interest. Within-subject correlation analysis is also employed in a single subject level, which utilizes cognitive fluctuations in a shorter time period by correlating the behavioral index with the brain activity across trials. In the present study, the within-subject analysis was applied to the stop-signal task, a standard task to probe response inhibition, where efficiency of response inhibition can be evaluated by the stop-signal reaction time (SSRT. Since the SSRT is estimated, by definition, not in a trial basis but from pooled trials, the correlation across runs was calculated between the SSRT and the brain activity related to response inhibition. The within-subject correlation revealed negative correlations in the anterior cingulate cortex and the cerebellum. Moreover, the dissociation pattern was observed in the within-subject analysis when earlier vs. later parts of the runs were analyzed: negative correlation was dominant in earlier runs, whereas positive correlation was dominant in later runs. Regions of interest analyses revealed that the negative correlation in the anterior cingulate cortex, but not in the cerebellum, was dominant in earlier runs, suggesting multiple mechanisms associated with inhibitory processes that fluctuate on a run-by-run basis. These results indicate that the within-subject analysis compliments the across-subject analysis by highlighting different aspects of cognitive/affective processes related to response inhibition.

The interplay of attention economics and computer-aided detection marks in screening mammography

Science.gov (United States)

Schwartz, Tayler M.; Sridharan, Radhika; Wei, Wei; Lukyanchenko, Olga; Geiser, William; Whitman, Gary J.; Haygood, Tamara Miner

2016-03-01

Introduction: According to attention economists, overabundant information leads to decreased attention for individual pieces of information. Computer-aided detection (CAD) alerts radiologists to findings potentially associated with breast cancer but is notorious for creating an abundance of false-positive marks. We suspected that increased CAD marks do not lengthen mammogram interpretation time, as radiologists will selectively disregard these marks when present in larger numbers. We explore the relevance of attention economics in mammography by examining how the number of CAD marks affects interpretation time. Methods: We performed a retrospective review of bilateral digital screening mammograms obtained between January 1, 2011 and February 28, 2014, using only weekend interpretations to decrease distractions and the likelihood of trainee participation. We stratified data according to reader and used ANOVA to assess the relationship between number of CAD marks and interpretation time. Results: Ten radiologists, with median experience after residency of 12.5 years (range 6 to 24,) interpreted 1849 mammograms. When accounting for number of images, Breast Imaging Reporting and Data System category, and breast density, increasing numbers of CAD marks was correlated with longer interpretation time only for the three radiologists with the fewest years of experience (median 7 years.) Conclusion: For the 7 most experienced readers, increasing CAD marks did not lengthen interpretation time. We surmise that as CAD marks increase, the attention given to individual marks decreases. Experienced radiologists may rapidly dismiss larger numbers of CAD marks as false-positive, having learned that devoting extra attention to such marks does not improve clinical detection.

Scent marking in a territorial African antelope: I. The maintenance of borders between male oribi.

Science.gov (United States)

Brashares; Arcese

1999-01-01

Scent marking is ubiquitous among the dwarf antelope and gazelles of Africa, but its function has been the subject of debate. This study examined preorbital gland scent marking in the oribi, Ourebia ourebi, a territorial African antelope. Several hypotheses for the function of scent marking by territorial antelope were tested with observational data. Of these, the hypotheses that scent marking is driven by intrasexual competition between neighbouring males, and that marks serve as an honest advertisement of a male's ability to defend his territory from rivals, were supported best. Thirty-three territorial male oribi on 23 territories marked most at borders shared with other territorial males, and territorial males marked more often at borders shared with multimale groups than at borders shared with a single male. This suggests that males perceived neighbouring male groups as a greater threat to territory ownership than neighbouring males that defended their territories without the aid of adult subordinates. Marking rate was unrelated to territory size or the number of females on adjacent territories, but males with many male neighbours marked at higher rates than those with fewer male neighbours. These results suggest that the presence of male neighbours has a greater effect on the scent marking behaviour of territorial antelope than has been considered previously. Copyright 1999 The Association for the Study of Animal Behaviour.

Comparison of muscle/lean mass measurement methods: correlation with functional and biochemical testing.

Science.gov (United States)

Buehring, B; Siglinsky, E; Krueger, D; Evans, W; Hellerstein, M; Yamada, Y; Binkley, N

2018-03-01

DXA-measured lean mass is often used to assess muscle mass but has limitations. Thus, we compared DXA lean mass with two novel methods-bioelectric impedance spectroscopy and creatine (methyl-d3) dilution. The examined methodologies did not measure lean mass similarly and the correlation with muscle biomarkers/function varied. Muscle function tests predict adverse health outcomes better than lean mass measurement. This may reflect limitations of current mass measurement methods. Newer approaches, e.g., bioelectric impedance spectroscopy (BIS) and creatine (methyl-d3) dilution (D3-C), may more accurately assess muscle mass. We hypothesized that BIS and D3-C measured muscle mass would better correlate with function and bone/muscle biomarkers than DXA measured lean mass. Evaluations of muscle/lean mass, function, and serum biomarkers were obtained in older community-dwelling adults. Mass was assessed by DXA, BIS, and orally administered D3-C. Grip strength, timed up and go, and jump power were examined. Potential muscle/bone serum biomarkers were measured. Mass measurements were compared with functional and serum data using regression analyses; differences between techniques were determined by paired t tests. Mean (SD) age of the 112 (89F/23M) participants was 80.6 (6.0) years. The lean/muscle mass assessments were correlated (.57-.88) but differed (p Lean mass measures were unrelated to the serum biomarkers measured. These three methodologies do not similarly measure muscle/lean mass and should not be viewed as being equivalent. Functional tests assessing maximal muscle strength/power (grip strength and jump power) correlated with all mass measures whereas gait speed was not. None of the selected serum measures correlated with mass. Efforts to optimize muscle mass assessment and identify their relationships with health outcomes are needed.

Inference of Functionally-Relevant N-acetyltransferase Residues Based on Statistical Correlations.

Directory of Open Access Journals (Sweden)

Andrew F Neuwald

2016-12-01

Full Text Available Over evolutionary time, members of a superfamily of homologous proteins sharing a common structural core diverge into subgroups filling various functional niches. At the sequence level, such divergence appears as correlations that arise from residue patterns distinct to each subgroup. Such a superfamily may be viewed as a population of sequences corresponding to a complex, high-dimensional probability distribution. Here we model this distribution as hierarchical interrelated hidden Markov models (hiHMMs, which describe these sequence correlations implicitly. By characterizing such correlations one may hope to obtain information regarding functionally-relevant properties that have thus far evaded detection. To do so, we infer a hiHMM distribution from sequence data using Bayes' theorem and Markov chain Monte Carlo (MCMC sampling, which is widely recognized as the most effective approach for characterizing a complex, high dimensional distribution. Other routines then map correlated residue patterns to available structures with a view to hypothesis generation. When applied to N-acetyltransferases, this reveals sequence and structural features indicative of functionally important, yet generally unknown biochemical properties. Even for sets of proteins for which nothing is known beyond unannotated sequences and structures, this can lead to helpful insights. We describe, for example, a putative coenzyme-A-induced-fit substrate binding mechanism mediated by arginine residue switching between salt bridge and π-π stacking interactions. A suite of programs implementing this approach is available (psed.igs.umaryland.edu.

Inference of Functionally-Relevant N-acetyltransferase Residues Based on Statistical Correlations.

Science.gov (United States)

Neuwald, Andrew F; Altschul, Stephen F

2016-12-01

Over evolutionary time, members of a superfamily of homologous proteins sharing a common structural core diverge into subgroups filling various functional niches. At the sequence level, such divergence appears as correlations that arise from residue patterns distinct to each subgroup. Such a superfamily may be viewed as a population of sequences corresponding to a complex, high-dimensional probability distribution. Here we model this distribution as hierarchical interrelated hidden Markov models (hiHMMs), which describe these sequence correlations implicitly. By characterizing such correlations one may hope to obtain information regarding functionally-relevant properties that have thus far evaded detection. To do so, we infer a hiHMM distribution from sequence data using Bayes' theorem and Markov chain Monte Carlo (MCMC) sampling, which is widely recognized as the most effective approach for characterizing a complex, high dimensional distribution. Other routines then map correlated residue patterns to available structures with a view to hypothesis generation. When applied to N-acetyltransferases, this reveals sequence and structural features indicative of functionally important, yet generally unknown biochemical properties. Even for sets of proteins for which nothing is known beyond unannotated sequences and structures, this can lead to helpful insights. We describe, for example, a putative coenzyme-A-induced-fit substrate binding mechanism mediated by arginine residue switching between salt bridge and π-π stacking interactions. A suite of programs implementing this approach is available (psed.igs.umaryland.edu).

Estimation of sesqui-carbide fraction for MARK-I fuel

International Nuclear Information System (INIS)

Vana Varamban, S.; Ananthasivan, K.

2016-01-01

Sesqui-carbide content of FBTR bi-phasic mixed carbide is specified as 5-20 wt.%. For each batch of fuel production, the sesqui-carbide (M2C3) content is being determined by a K-ratio method using XRD information. There is a need to evolve an alternate method for qualitative determination of M2C3 content for a fabricated FBTR fuel pellet. Two independent approaches resulted in a correlation between overall carbon content and the M2C3 phase fraction. The thermodynamic calculations agree well with the stoichiometric correlation between the overall carbon content and the M2C3 phase fraction in FBTR MARK I fuel

Functional and morphological alterations of the stomach in case of irradiation of the para-aortic area

Energy Technology Data Exchange (ETDEWEB)

Beyer-Enke, S.A.; Gladisch, R.; Heine, M.; Georgi, M.

1987-12-01

Six assays were conducted in order to determine some functional and morphological parameters of the gastric mucosa in patients who underwent Co/sup 60/ irradiations of the para-aortic area. Slight as well as marked morphological alterations were observed whereas the functional alterations were found to be marked in all cases. Basal gastric secretion and serum gastrin level showed a continous reduction, however, in case of severe gastritis the stimulated secretion was increased. A possible correlation with increased tissue histamine levels is discussed.

A Study on the Development of Playback Control Software for Mark5B VSI System

Directory of Open Access Journals (Sweden)

S. J. Oh

2010-06-01

Full Text Available We developed the playback control software for a high-speed playback system which is a component of the Korea-Japan Joint VLBI Correlator (KJJVC. The Mark5B system, which is a recorder and playback system used in the Korean VLBI Network (KVN, has two kinds of operation mode. That is to say, the station unit (SU mode, which is for the present Mark4 system, and the VSI mode, which is for the new VLBI standard interface (VSI system. The software for SU is already developed and widely used in the Mark4 type VLBI system, but the software for VSI has only been developed for recording. The new VLBI system is designed with a VSI interface for compatibility between different systems. Therefore, the playback control software development of the VSI mode is needed for KVN. In this work, we developed the playback control software of the Mark5B VSI mode. The developed playback control software consists of an application part for data playing back, a data input/output part for the VSI board, a module for the StreamStor RAID board, and a user interface part, including an observation time control part. To verify the performance of developed playback control software, the playback and correlation experiments were performed using the real observation data in Mark5B system and KJJVC. To check the observation time control, the data playback experiment was performed between the Mark5B and Raw VLBI Data Buffer (RVDB systems. Through the experimental results, we confirmed the performance of developed playback control software in the Mark5B VSI mode.

Charmonium correlators and spectral functions at finite temperature

Energy Technology Data Exchange (ETDEWEB)

Ding,H.T.; Kaczmarek, O.; Karsch, F.; Satz, H.

2008-09-01

We present an operational approach to address the in-medium behavior of charmonium and analyze the reliability of maximum entropy method (MEM). We study the dependences of the ratio of correlators to the reconstructed one and the free one on the resonance's width and the continuum's threshold. Furthermore, we discuss the issue of the default model dependence of the spectral function obtained from MEM.

The PROMIS physical function correlates with the QuickDASH in patients with upper extremity illness.

Science.gov (United States)

Overbeek, Celeste L; Nota, Sjoerd P F T; Jayakumar, Prakash; Hageman, Michiel G; Ring, David

2015-01-01

To assess disability more efficiently with less burden on the patient, the National Institutes of Health has developed the Patient Reported Outcomes Measurement Information System (PROMIS) Physical Function-an instrument based on item response theory and using computer adaptive testing (CAT). Initially, upper and lower extremity disabilities were not separated and we were curious if the PROMIS Physical Function CAT could measure upper extremity disability and the Quick Disability of Arm, Shoulder and Hand (QuickDASH). We aimed to find correlation between the PROMIS Physical Function and the QuickDASH questionnaires in patients with upper extremity illness. Secondarily, we addressed whether the PROMIS Physical Function and QuickDASH correlate with the PROMIS Depression CAT and PROMIS Pain Interference CAT instruments. Finally, we assessed factors associated with QuickDASH and PROMIS Physical Function in multivariable analysis. A cohort of 93 outpatients with upper extremity illnesses completed the QuickDASH and three PROMIS CAT questionnaires: Physical Function, Pain Interference, and Depression. Pain intensity was measured with an 11-point ordinal measure (0-10 numeric rating scale). Correlation between PROMIS Physical Function and the QuickDASH was assessed. Factors that correlated with the PROMIS Physical Function and QuickDASH were assessed in multivariable regression analysis after initial bivariate analysis. There was a moderate correlation between the PROMIS Physical Function and the QuickDASH questionnaire (r=-0.55, p<0.001). Greater disability as measured with the PROMIS and QuickDASH correlated most strongly with PROMIS Depression (r=-0.35, p<0.001 and r=0.34, p<0.001 respectively) and Pain Interference (r=-0.51, p<0.001 and r=0.74, p<0.001 respectively). The factors accounting for the variability in PROMIS scores are comparable to those for the QuickDASH except that the PROMIS Physical Function is influenced by other pain conditions while the QuickDASH is

A model for the two-point velocity correlation function in turbulent channel flow

International Nuclear Information System (INIS)

Sahay, A.; Sreenivasan, K.R.

1996-01-01

A relatively simple analytical expression is presented to approximate the equal-time, two-point, double-velocity correlation function in turbulent channel flow. To assess the accuracy of the model, we perform the spectral decomposition of the integral operator having the model correlation function as its kernel. Comparisons of the empirical eigenvalues and eigenfunctions with those constructed from direct numerical simulations data show good agreement. copyright 1996 American Institute of Physics

Tissue-specific RNA expression marks distant-acting developmental enhancers.

Directory of Open Access Journals (Sweden)

Han Wu

2014-09-01

Full Text Available Short non-coding transcripts can be transcribed from distant-acting transcriptional enhancer loci, but the prevalence of such enhancer RNAs (eRNAs within the transcriptome, and the association of eRNA expression with tissue-specific enhancer activity in vivo remain poorly understood. Here, we investigated the expression dynamics of tissue-specific non-coding RNAs in embryonic mouse tissues via deep RNA sequencing. Overall, approximately 80% of validated in vivo enhancers show tissue-specific RNA expression that correlates with tissue-specific enhancer activity. Globally, we identified thousands of tissue-specifically transcribed non-coding regions (TSTRs displaying various genomic hallmarks of bona fide enhancers. In transgenic mouse reporter assays, over half of tested TSTRs functioned as enhancers with reproducible activity in the predicted tissue. Together, our results demonstrate that tissue-specific eRNA expression is a common feature of in vivo enhancers, as well as a major source of extragenic transcription, and that eRNA expression signatures can be used to predict tissue-specific enhancers independent of known epigenomic enhancer marks.

On strong-coupling correlation functions of circular Wilson loops and local operators

International Nuclear Information System (INIS)

Alday, Luis F; Tseytlin, Arkady A

2011-01-01

Motivated by the problem of understanding 3-point correlation functions of gauge-invariant operators in N=4 super Yang-Mills theory we consider correlators involving Wilson loops and a 'light' operator with fixed quantum numbers. At leading order in the strong-coupling expansion such correlators are given by the 'light' vertex operator evaluated on a semiclassical string world surface ending on the corresponding loops at the boundary of AdS 5 x S 5 . We study in detail the example of a correlator of two concentric circular Wilson loops and a dilaton vertex operator. The resulting expression is given by an integral of combinations of elliptic functions and can be computed analytically in some special limits. We also consider a generalization of the minimal surface ending on two circles to the case of non-zero angular momentum J in S 5 and discuss a special limit when one of the Wilson loops is effectively replaced by a 'heavy' operator with charge J. (paper)

Lujan Mark-4

Energy Technology Data Exchange (ETDEWEB)

Mocko, Michael Jeffrey [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zavorka, Lukas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Koehler, Paul E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-11-13

This is a review of Mark-IV target neutronics design. It involved the major redesign of the upper tier, offering harder neutron spectra for upper-tier FPs; a redesign of the high-resolution (HR) moderator; and a preservation of the rest of Mark-III features.

A perturbative approach to the redshift space correlation function: beyond the Standard Model

Science.gov (United States)

Bose, Benjamin; Koyama, Kazuya

2017-08-01

We extend our previous redshift space power spectrum code to the redshift space correlation function. Here we focus on the Gaussian Streaming Model (GSM). Again, the code accommodates a wide range of modified gravity and dark energy models. For the non-linear real space correlation function used in the GSM we use the Fourier transform of the RegPT 1-loop matter power spectrum. We compare predictions of the GSM for a Vainshtein screened and Chameleon screened model as well as GR. These predictions are compared to the Fourier transform of the Taruya, Nishimichi and Saito (TNS) redshift space power spectrum model which is fit to N-body data. We find very good agreement between the Fourier transform of the TNS model and the GSM predictions, with <= 6% deviations in the first two correlation function multipoles for all models for redshift space separations in 50Mpch <= s <= 180Mpc/h. Excellent agreement is found in the differences between the modified gravity and GR multipole predictions for both approaches to the redshift space correlation function, highlighting their matched ability in picking up deviations from GR. We elucidate the timeliness of such non-standard templates at the dawn of stage-IV surveys and discuss necessary preparations and extensions needed for upcoming high quality data.

Minimal Marking: A Success Story

Science.gov (United States)

McNeilly, Anne

2014-01-01

The minimal-marking project conducted in Ryerson's School of Journalism throughout 2012 and early 2013 resulted in significantly higher grammar scores in two first-year classes of minimally marked university students when compared to two traditionally marked classes. The "minimal-marking" concept (Haswell, 1983), which requires…

Advanced correlation grid: Analysis and visualisation of functional connectivity among multiple spike trains.

Science.gov (United States)

Masud, Mohammad Shahed; Borisyuk, Roman; Stuart, Liz

2017-07-15

This study analyses multiple spike trains (MST) data, defines its functional connectivity and subsequently visualises an accurate diagram of connections. This is a challenging problem. For example, it is difficult to distinguish the common input and the direct functional connection of two spike trains. The new method presented in this paper is based on the traditional pairwise cross-correlation function (CCF) and a new combination of statistical techniques. First, the CCF is used to create the Advanced Correlation Grid (ACG) correlation where both the significant peak of the CCF and the corresponding time delay are used for detailed analysis of connectivity. Second, these two features of functional connectivity are used to classify connections. Finally, the visualization technique is used to represent the topology of functional connections. Examples are presented in the paper to demonstrate the new Advanced Correlation Grid method and to show how it enables discrimination between (i) influence from one spike train to another through an intermediate spike train and (ii) influence from one common spike train to another pair of analysed spike trains. The ACG method enables scientists to automatically distinguish between direct connections from spurious connections such as common source connection and indirect connection whereas existing methods require in-depth analysis to identify such connections. The ACG is a new and effective method for studying functional connectivity of multiple spike trains. This method can identify accurately all the direct connections and can distinguish common source and indirect connections automatically. Copyright © 2017 Elsevier B.V. All rights reserved.

Towards a Density Functional Theory Exchange-Correlation Functional able to describe localization/delocalization

Science.gov (United States)

Mattsson, Ann E.; Wills, John M.

2013-03-01

The inability to computationally describe the physics governing the properties of actinides and their alloys is the poster child of failure of existing Density Functional Theory exchange-correlation functionals. The intricate competition between localization and delocalization of the electrons, present in these materials, exposes the limitations of functionals only designed to properly describe one or the other situation. We will discuss the manifestation of this competition in real materials and propositions on how to construct a functional able to accurately describe properties of these materials. I addition we will discuss both the importance of using the Dirac equation to describe the relativistic effects in these materials, and the connection to the physics of transition metal oxides. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Fast methods for spatially correlated multilevel functional data

KAUST Repository

Staicu, A.-M.

2010-01-19

We propose a new methodological framework for the analysis of hierarchical functional data when the functions at the lowest level of the hierarchy are correlated. For small data sets, our methodology leads to a computational algorithm that is orders of magnitude more efficient than its closest competitor (seconds versus hours). For large data sets, our algorithm remains fast and has no current competitors. Thus, in contrast to published methods, we can now conduct routine simulations, leave-one-out analyses, and nonparametric bootstrap sampling. Our methods are inspired by and applied to data obtained from a state-of-the-art colon carcinogenesis scientific experiment. However, our models are general and will be relevant to many new data sets where the object of inference are functions or images that remain dependent even after conditioning on the subject on which they are measured. Supplementary materials are available at Biostatistics online.

Three-particle correlation functions of quasi-two-dimensional one-component and binary colloid suspensions.

Science.gov (United States)

Ho, Hau My; Lin, Binhua; Rice, Stuart A

2006-11-14

We report the results of experimental determinations of the triplet correlation functions of quasi-two-dimensional one-component and binary colloid suspensions in which the colloid-colloid interaction is short ranged. The suspensions studied range in density from modestly dilute to solid. The triplet correlation function of the one-component colloid system reveals extensive ordering deep in the liquid phase. At the same density the ordering of the larger diameter component in a binary colloid system is greatly diminished by a very small amount of the smaller diameter component. The possible utilization of information contained in the triplet correlation function in the theory of melting of a quasi-two-dimensional system is briefly discussed.

Conformal scalar field on the hyperelliptic curve and critical Ashkin-Teller multipoint correlation functions

International Nuclear Information System (INIS)

Zamolodchikov, A.B.

1987-01-01

A multipoint conformal block of Ramond states of the two-dimensional free scalar field is calculated. This function is related to the free energy of the scalar field on the hyperelliptic Riemann surface under a particular choice of boundary conditions. Being compactified on the circle this field leads to the crossing symmetric correlation functions with a discrete spectrum of scale dimensions. These functions are supposed to describe multipoint spin correlations of the critical Ashkin-Teller model. (orig.)

Emotional Availability Modulates Electrophysiological Correlates of Executive Functions in Preschool Children

OpenAIRE

Schneider-Hassloff, Henriette; Zw?nitzer, Annabel; K?nster, Anne K.; Mayer, Carmen; Ziegenhain, Ute; Kiefer, Markus

2016-01-01

Executive functions (EFs) – a set of cognitive control abilities – mediate resilience to stress and are associated with academic achievement and health throughout life. They are crucially linked to prefrontal cortex function as well as to other cortical and subcortical brain functions, which are maturing throughout childhood at different rates. Recent behavioral research suggested that children’s EFs were related to parenting quality and child attachment security, but the neural correlates of...

The Potts model and flows. 1. The pair correlation function

International Nuclear Information System (INIS)

Essam, J.W.; Tsallis, C.

1985-01-01

It is shown that the partition function for the lambda-state Potts model with pair-interactions is related to the expected number of integer mod-lambda flows in a percolation model. The relation is generalised to the pair correlation function. The resulting high temperature expansion coefficients are shown to be the flow polynomials of graph theory. An observation of Tsallis and Levy concerning the equivalent transmissivity of a cluster is also proved. (Author) [pt

Correlation between the body balance and functional capacity from elderly with chronic vestibular disorders.

Science.gov (United States)

Sousa, Raquel Ferreira de; Gazzola, Juliana Maria; Ganança, Maurício Malavasi; Paulino, Célia Aparecida

2011-01-01

Vestibular disorders are common among the elderly, mainly resulting in dizziness and imbalance--symptoms which can impact daily routine activities. To study the correlation between body balance and functional capacity and a comparison of risk of falls, actual falls and the functional capacity of the elderly with chronic vestibular dysfunctions. A cross-sectional, clinical and experimental study with 50 senior citizens--60 to 86 years, with chronic peripheral vestibular dysfunction. These participants underwent body balance assessment by the Dynamic Gait Index (DGI) and functional capacity assessment by the Functional Independence Measure (FIM). The data was tested using the Spearman correlation and comparison tests, Mann-Whitney and Kruskal-Wallis, being α=5% (0.05). There was a significant correlation between the total DGI score and all FIM scores, especially the total score (r=0.447; pfunctional capacity in elderly patients with the highest risk of falling (pfunctional capacity in elderly patients with peripheral vestibular disorders, that is: the better the balance, the better the individual's functional capacity. In addition, a worse functional capacity increases the individual's risk of falling.

Mirage in temporal correlation functions for baryon-baryon interactions in lattice QCD

International Nuclear Information System (INIS)

Iritani, T.; Doi, T.; Aoki, S.; Gongyo, S.; Hatsuda, T.; Ikeda, Y.; Inoue, T.; Ishii, N.; Murano, K.; Nemura, H.; Sasaki, K.

2016-01-01

Single state saturation of the temporal correlation function is a key condition to extract physical observables such as energies and matrix elements of hadrons from lattice QCD simulations. A method commonly employed to check the saturation is to seek for a plateau of the observables for large Euclidean time. Identifying the plateau in the cases having nearby states, however, is non-trivial and one may even be misled by a fake plateau. Such a situation takes place typically for a system with two or more baryons. In this study, we demonstrate explicitly the danger from a possible fake plateau in the temporal correlation functions mainly for two baryons (ΞΞ and NN), and three and four baryons ("3He and "4He) as well, employing (2+1)-flavor lattice QCD at m_π=0.51 GeV on four lattice volumes with L= 2.9, 3.6, 4.3 and 5.8 fm. Caution is required when drawing conclusions about the bound NN, 3N and 4N systems based only on the standard plateau fitting of the temporal correlation functions.

Mark Stock | NREL

Science.gov (United States)

Stock Mark Stock Scientific Visualization Specialist Mark.Stock@nrel.gov | 303-275-4174 Dr. Stock , virtual reality, parallel computing, and manipulation of large spatial data sets. As an artist, he creates . Stock built the SUNLIGHT artwork that is installed on the Webb Building in downtown Denver. In addition

Genetic and Environmental Basis in Phenotype Correlation Between Physical Function and Cognition in Aging Chinese Twins

DEFF Research Database (Denmark)

Xu, Chunsheng; Zhang, Dongfeng; Tian, Xiaocao

2017-01-01

for cognition with handgrip strength, FTSST, near visual acuity, and number of teeth lost. Cognitive function was genetically related to pulmonary function. The FTSST and cognition shared almost the same common environmental factors but only part of the unique environmental factors, both with negative......Although the correlation between cognition and physical function has been well studied in the general population, the genetic and environmental nature of the correlation has been rarely investigated. We conducted a classical twin analysis on cognitive and physical function, including forced...... and cognitive function. Bivariate analysis showed mildly positively genetic correlations between cognition and FEV1, r G = 0.23 [95% CI: 0.03, 0.62], as well as FVC, r G = 0.35 [95% CI: 0.06, 1.00]. We found that FTSST and cognition presented very high common environmental correlation, r C = -1.00 [95% CI: -1...

Correlation between movement of the feet and motor function of children with chronic encephalopathy

Directory of Open Access Journals (Sweden)

Táubuta Gomes Souza

Full Text Available Abstract Introduction: Chronic non-progressive encephalopathy (CNPE is one of the most common causes of physical deformities in childhood. It is characterized by non-progressive neuropathological abnormalities of the developing brain, which results in neuromotor impairments and changes in posture and movement. Objective: To evaluate foot deformities in children with CNPE, by measuring the joint amplitude and correlating these measures with the scores of the Gross Motor Function Measure (GMFM-88, using all its five dimensions. Methods: Cross-sectional and descriptive study with a sample of 17 children. The data collection instruments used were manual goniometer and the Gross Motor Function Measure test (GMFM-88. Data were analyzed using the program SPSS version 18, and the Pearson correlation test as a measure of association. Results: Children with chronic encephalopathy and a reduced amplitude motion have lower capacity in motor function. Statistically significant correlation was found for the right dorsiflexion angle (p = 0.023, left dorsiflexion angle (p = 0.019, right inversion (p = 0.040, left inversion (p = 0.034 and left eversion (p = 0.018. There was no statistically significant correlation for the right eversion (p > 0.05. Conclusion: Musculoskeletal disorders associated with CNPE and foot deformities interfere negatively in motor function, compromising the functional performance of these children.

The optimal control of ITU TRIGA Mark II Reactor

International Nuclear Information System (INIS)

Can, Burhanettin

2008-01-01

In this study, optimal control of ITU TRIGA Mark-II Reactor is discussed. A new controller has been designed for ITU TRIGA Mark-II Reactor. The controller consists of main and auxiliary controllers. The form is based on Pontragyn's Maximum Principle and the latter is based on PID approach. For the desired power program, a cubic function is chosen. Integral Performance Index includes the mean square of error function and the effect of selected period on the power variation. YAVCAN2 Neutronic - Thermal -Hydraulic code is used to solve the equations, namely 11 equations, dealing with neutronic - thermal - hydraulic behavior of the reactor. For the controller design, a new code, KONTCAN, is written. In the application of the code, it is seen that the controller controls the reactor power to follow the desired power program. The overshoot value alters between 100 W and 500 W depending on the selected period. There is no undershoot. The controller rapidly increases reactivity, then decreases, after that increases it until the effect of temperature feedback is compensated. Error function varies between 0-1 kW. (author)

Dialectica Interpretation with Marked Counterexamples

Directory of Open Access Journals (Sweden)

Trifon Trifonov

2011-01-01

Full Text Available Goedel's functional "Dialectica" interpretation can be used to extract functional programs from non-constructive proofs in arithmetic by employing two sorts of higher-order witnessing terms: positive realisers and negative counterexamples. In the original interpretation decidability of atoms is required to compute the correct counterexample from a set of candidates. When combined with recursion, this choice needs to be made for every step in the extracted program, however, in some special cases the decision on negative witnesses can be calculated only once. We present a variant of the interpretation in which the time complexity of extracted programs can be improved by marking the chosen witness and thus avoiding recomputation. The achieved effect is similar to using an abortive control operator to interpret computational content of non-constructive principles.

Improvement of a new rotation function for molecular replacement by designing new scoring functions and dynamic correlation coefficient

Science.gov (United States)

Jiang, Fan; Ding, Wei

2010-10-01

A previously published new rotation function has been improved by using a dynamic correlation coefficient as well as two new scoring functions of relative entropy and mean-square-residues to make the rotation function more robust and independent of a specific set of weights for scoring and ranking. The previously described new rotation function calculates the rotation function of molecular replacement by matching the search model directly with the Patterson vector map. The signal-to-noise ratio for the correct match was increased by averaging all the matching peaks. Several matching scores were employed to evaluate the goodness of matching. These matching scores were then combined into a single total score by optimizing a set of weights using the linear regression method. It was found that there exists an optimal set of weights that can be applied to the global rotation search and the correct solution can be ranked in the top 100 or less. However, this set of optimal weights in general is dependent on the search models and the crystal structures with different space groups and cell parameters. In this work, we try to solve this problem by designing a dynamic correlation coefficient. It is shown that the dynamic correlation coefficient works for a variety of space groups and cell parameters in the global search of rotation function. We also introduce two new matching scores: relative entropy and mean-square-residues. Last but not least, we discussed a valid method for the optimization of the adjustable parameters for matching vectors.

Improvement of a new rotation function for molecular replacement by designing new scoring functions and dynamic correlation coefficient

International Nuclear Information System (INIS)

Fan, Jiang; Wei, Ding

2010-01-01

A previously published new rotation function has been improved by using a dynamic correlation coefficient as well as two new scoring functions of relative entropy and mean-square-residues to make the rotation function more robust and independent of a specific set of weights for scoring and ranking. The previously described new rotation function calculates the rotation function of molecular replacement by matching the search model directly with the Patterson vector map. The signal-to-noise ratio for the correct match was increased by averaging all the matching peaks. Several matching scores were employed to evaluate the goodness of matching. These matching scores were then combined into a single total score by optimizing a set of weights using the linear regression method. It was found that there exists an optimal set of weights that can be applied to the global rotation search and the correct solution can be ranked in the top 100 or less. However, this set of optimal weights in general is dependent on the search models and the crystal structures with different space groups and cell parameters. In this work, we try to solve this problem by designing a dynamic correlation coefficient. It is shown that the dynamic correlation coefficient works for a variety of space groups and cell parameters in the global search of rotation function. We also introduce two new matching scores: relative entropy and mean-square-residues. Last but not least, we discussed a valid method for the optimization of the adjustable parameters for matching vectors. (condensed matter: structure, thermal and mechanical properties)

Conformal correlation functions in the Brownian loop soup

Science.gov (United States)

Camia, Federico; Gandolfi, Alberto; Kleban, Matthew

2016-01-01

We define and study a set of operators that compute statistical properties of the Brownian loop soup, a conformally invariant gas of random Brownian loops (Brownian paths constrained to begin and end at the same point) in two dimensions. We prove that the correlation functions of these operators have many of the properties of conformal primaries in a conformal field theory, and compute their conformal dimension. The dimensions are real and positive, but have the novel feature that they vary continuously as a periodic function of a real parameter. We comment on the relation of the Brownian loop soup to the free field, and use this relation to establish that the central charge of the loop soup is twice its intensity.

Conformal correlation functions in the Brownian loop soup

Energy Technology Data Exchange (ETDEWEB)

Camia, Federico, E-mail: federico.camia@nyu.edu [New York University Abu Dhabi (United Arab Emirates); VU University, Amsterdam (Netherlands); Gandolfi, Alberto, E-mail: albertogandolfi@nyu.edu [New York University Abu Dhabi (United Arab Emirates); Università di Firenze (Italy); Kleban, Matthew, E-mail: kleban@nyu.edu [New York University Abu Dhabi (United Arab Emirates); Center for Cosmology and Particle Physics, Department of Physics, New York University (United States)

2016-01-15

We define and study a set of operators that compute statistical properties of the Brownian loop soup, a conformally invariant gas of random Brownian loops (Brownian paths constrained to begin and end at the same point) in two dimensions. We prove that the correlation functions of these operators have many of the properties of conformal primaries in a conformal field theory, and compute their conformal dimension. The dimensions are real and positive, but have the novel feature that they vary continuously as a periodic function of a real parameter. We comment on the relation of the Brownian loop soup to the free field, and use this relation to establish that the central charge of the loop soup is twice its intensity.

Conformal correlation functions in the Brownian loop soup

Directory of Open Access Journals (Sweden)

Federico Camia

2016-01-01

Full Text Available We define and study a set of operators that compute statistical properties of the Brownian loop soup, a conformally invariant gas of random Brownian loops (Brownian paths constrained to begin and end at the same point in two dimensions. We prove that the correlation functions of these operators have many of the properties of conformal primaries in a conformal field theory, and compute their conformal dimension. The dimensions are real and positive, but have the novel feature that they vary continuously as a periodic function of a real parameter. We comment on the relation of the Brownian loop soup to the free field, and use this relation to establish that the central charge of the loop soup is twice its intensity.

Endurance Capacity Is Not Correlated with Endothelial Function in Male University Students

Science.gov (United States)

Wu, Fang; Su, Chen; Fan, Zhen-guo; Zhu, Zhu; Tao, Jun; Huang, Yi-jun

2014-01-01

Background Endurance capacity, assessed by 1000-meter (1000 m) run of male university students, is an indicator of cardiovascular fitness in Chinese students physical fitness surveillance. Although cardiovascular fitness is related to endothelial function closely in patients with cardiovascular diseases, it remains unclear whether endurance capacity correlates with endothelial function, especially with circulating endothelial microparticles (EMPs), a new sensitive marker of endothelial dysfunction in young students. The present study aimed to investigate the relationship between endurance capacity and endothelial function in male university students. Methods Forty-seven healthy male university students (mean age, 20.1±0.6 years; mean height, 172.4±6.3 cm; and mean weight, 60.0±8.2 kg) were recruited in this study. The measurement procedure of 1000 m run time was followed to Chinese national students Constitutional Health Criterion. Endothelium function was assessed by flow-mediated vasodilation (FMD) in the brachial artery measured by ultrasonic imaging, and the level of circulating EMPs was measured by flow cytometry. Cardiovascular fitness indicator - maximal oxygen uptake (VO2 max) - was also measured on a cycle ergometer using a portable gas analyzer. Results 1000 m run time was correlated with VO2max (r = −0.399, p0.05). Conclusion The correlations between endurance capacity or cardiovascular fitness and endothelial function were not found in healthy Chinese male university students. These results suggest that endurance capacity may not reflect endothelial function in healthy young adults with well preserved FMD and low level of circulating CD31+/CD42-EMPs. PMID:25101975

Correlation functions for fully or partially state-resolved reactive scattering calculations

International Nuclear Information System (INIS)

Manthe, Uwe; Welsch, Ralph

2014-01-01

Flux correlation functions and the quantum transition state concept are important tools for the accurate description of polyatomic reaction processes. Combined with the multi-configurational time-dependent Hartree approach, they facilitate rigorous full-dimensional calculations of cumulative and initial-state selected reaction probabilities for six atom reactions. In recent work [R. Welsch, F. Huarte-Larrañaga, and U. Manthe, J. Chem. Phys. 136, 064117 (2012)], an approach which allows one to calculate also state-to-state reaction probabilities within the quantum transition state concept has been introduced. This article presents further developments. Alternative generalized flux correlation functions are introduced and discussed. Equations for the calculation of fully state-resolved differential cross section using arbitrary definitions of the body fixed frame are derived. An approach for the efficient calculation of partially state-resolved observables as a function of the collision energy is introduced. Finally, numerical test studying the D + H 2 reaction illustrate important aspects of the formalism

A perturbative approach to the redshift space correlation function: beyond the Standard Model

Energy Technology Data Exchange (ETDEWEB)

Bose, Benjamin; Koyama, Kazuya, E-mail: benjamin.bose@port.ac.uk, E-mail: kazuya.koyama@port.ac.uk [Institute of Cosmology and Gravitation, University of Portsmouth, Burnaby Road, Portsmouth, Hampshire, PO1 3FX (United Kingdom)

2017-08-01

We extend our previous redshift space power spectrum code to the redshift space correlation function. Here we focus on the Gaussian Streaming Model (GSM). Again, the code accommodates a wide range of modified gravity and dark energy models. For the non-linear real space correlation function used in the GSM we use the Fourier transform of the RegPT 1-loop matter power spectrum. We compare predictions of the GSM for a Vainshtein screened and Chameleon screened model as well as GR. These predictions are compared to the Fourier transform of the Taruya, Nishimichi and Saito (TNS) redshift space power spectrum model which is fit to N-body data. We find very good agreement between the Fourier transform of the TNS model and the GSM predictions, with ≤ 6% deviations in the first two correlation function multipoles for all models for redshift space separations in 50Mpc h ≤ s ≤ 180Mpc/ h . Excellent agreement is found in the differences between the modified gravity and GR multipole predictions for both approaches to the redshift space correlation function, highlighting their matched ability in picking up deviations from GR. We elucidate the timeliness of such non-standard templates at the dawn of stage-IV surveys and discuss necessary preparations and extensions needed for upcoming high quality data.

Correlation of anatomy and function in medulla oblongata infarction.

Science.gov (United States)

Eggers, C; Fink, G R; Möller-Hartmann, W; Nowak, D A

2009-02-01

A presentation of all aspects of the dorsolateral medulla oblongata syndrome is clinically very rare to find. In most cases patients present with fragmentary symptoms, e.g. ipsilateral axial lateropulsion, nystagmus, dysarthria, dysphagia or hemiataxia. However, the clinical presentation and lesion anatomy at the level of the medulla oblongata is still unsatisfactory. The aim of this study was to correlate the functional deficit with structural MRI-data. We included thirteen patients (eight male, five female, mean age 65.5) with medulla oblongata infarction with clinically predominant ipsilateral axial lateropulsion and correlated clinical with structural deficits. Magnetic resonance imaging lesion mapping demonstrated ipsilateral axial lateropulsion to result from lesions of the spinocerebellar tract, the inferior cerebellar peduncle or the inferior vestibular nucleus. Nystagmus was associated with lesions of the inferior vestibular nucleus, dissociated sensory loss with the spinothalamic tract and hemiataxia with the spinocerebellar tract. Correlating dysfunction and lesion anatomy is a promising approach to enhance our knowledge on medulla oblongata topography.

Effects of different correlation metrics and preprocessing factors on small-world brain functional networks: a resting-state functional MRI study.

Science.gov (United States)

Liang, Xia; Wang, Jinhui; Yan, Chaogan; Shu, Ni; Xu, Ke; Gong, Gaolang; He, Yong

2012-01-01

Graph theoretical analysis of brain networks based on resting-state functional MRI (R-fMRI) has attracted a great deal of attention in recent years. These analyses often involve the selection of correlation metrics and specific preprocessing steps. However, the influence of these factors on the topological properties of functional brain networks has not been systematically examined. Here, we investigated the influences of correlation metric choice (Pearson's correlation versus partial correlation), global signal presence (regressed or not) and frequency band selection [slow-5 (0.01-0.027 Hz) versus slow-4 (0.027-0.073 Hz)] on the topological properties of both binary and weighted brain networks derived from them, and we employed test-retest (TRT) analyses for further guidance on how to choose the "best" network modeling strategy from the reliability perspective. Our results show significant differences in global network metrics associated with both correlation metrics and global signals. Analysis of nodal degree revealed differing hub distributions for brain networks derived from Pearson's correlation versus partial correlation. TRT analysis revealed that the reliability of both global and local topological properties are modulated by correlation metrics and the global signal, with the highest reliability observed for Pearson's-correlation-based brain networks without global signal removal (WOGR-PEAR). The nodal reliability exhibited a spatially heterogeneous distribution wherein regions in association and limbic/paralimbic cortices showed moderate TRT reliability in Pearson's-correlation-based brain networks. Moreover, we found that there were significant frequency-related differences in topological properties of WOGR-PEAR networks, and brain networks derived in the 0.027-0.073 Hz band exhibited greater reliability than those in the 0.01-0.027 Hz band. Taken together, our results provide direct evidence regarding the influences of correlation metrics and specific

Effects of different correlation metrics and preprocessing factors on small-world brain functional networks: a resting-state functional MRI study.

Directory of Open Access Journals (Sweden)

Xia Liang

Full Text Available Graph theoretical analysis of brain networks based on resting-state functional MRI (R-fMRI has attracted a great deal of attention in recent years. These analyses often involve the selection of correlation metrics and specific preprocessing steps. However, the influence of these factors on the topological properties of functional brain networks has not been systematically examined. Here, we investigated the influences of correlation metric choice (Pearson's correlation versus partial correlation, global signal presence (regressed or not and frequency band selection [slow-5 (0.01-0.027 Hz versus slow-4 (0.027-0.073 Hz] on the topological properties of both binary and weighted brain networks derived from them, and we employed test-retest (TRT analyses for further guidance on how to choose the "best" network modeling strategy from the reliability perspective. Our results show significant differences in global network metrics associated with both correlation metrics and global signals. Analysis of nodal degree revealed differing hub distributions for brain networks derived from Pearson's correlation versus partial correlation. TRT analysis revealed that the reliability of both global and local topological properties are modulated by correlation metrics and the global signal, with the highest reliability observed for Pearson's-correlation-based brain networks without global signal removal (WOGR-PEAR. The nodal reliability exhibited a spatially heterogeneous distribution wherein regions in association and limbic/paralimbic cortices showed moderate TRT reliability in Pearson's-correlation-based brain networks. Moreover, we found that there were significant frequency-related differences in topological properties of WOGR-PEAR networks, and brain networks derived in the 0.027-0.073 Hz band exhibited greater reliability than those in the 0.01-0.027 Hz band. Taken together, our results provide direct evidence regarding the influences of correlation metrics

Endocrine profiles and neuropsychologic correlates of functional hypothalamic amenorrhea in adolescents.

Science.gov (United States)

Bomba, Monica; Gambera, Alessandro; Bonini, Luisa; Peroni, Maria; Neri, Francesca; Scagliola, Pasquale; Nacinovich, Renata

2007-04-01

To determine trigger factors and neuropsychologic correlates of functional hypothalamic amenorrhea (FHA) in adolescence and to evaluate the correlations with the endocrine-metabolic profile. Cross-sectional comparison of adolescents with FHA and eumenorrheic controls Academic medical institution Twenty adolescent girls with FHA (aged <18 years) and 20 normal cycling girls All subjects underwent endocrine-gynecologic (hormone) and neuropsychiatric (tests and interview) investigations. A separate semistructured interview was also used to investigate parents. Gonadotropins, leptin, prolactin, androgens, estrogens, cortisol, carrier proteins (SHBG, insulin-like growth factor-binding protein 1), and metabolic parameters (insulin, insulin-like growth factor 1, thyroid hormones) were assayed in FHA and control subjects. All girls were evaluated using a test for depression, a test for disordered eating, and a psychodynamic semistructured interview. Adolescents with FHA showed a particular susceptibility to common life events, restrictive disordered eating, depressive traits, and psychosomatic disorders. The endocrine-metabolic profile was strictly correlated to the severity of the psychopathology. Functional hypothalamic amenorrhea in adolescence is due to a particular neuropsychologic vulnerability to stress, probably related to familial relationship styles, expressed by a proportional endocrine impairment.

On the physical part of the factorized correlation functions of the XXZ chain

International Nuclear Information System (INIS)

Boos, Herman; Goehmann, Frank

2009-01-01

It was recently shown by Jimbo et al (2008 arXiv:0811.0439) that the correlation functions of a generalized XXZ chain associated with an inhomogeneous six-vertex model with a disorder parameter α and with arbitrary inhomogeneities on the horizontal lines factorize and can all be expressed in terms of only two functions ρ and ω. Here we approach the description of the same correlation functions and, in particular, of the function ω from a different direction. We start from a novel multiple integral representation for the density matrix of a finite chain segment of length m in the presence of a disorder field α. We explicitly factorize the integrals for m = 2. Based on this, we present an alternative description of the function ω in terms of the solutions of certain linear and nonlinear integral equations. We then prove directly that the two definitions of ω describe the same function. The definition in the work of Jimbo et al (2008 arXiv:0811.0439) was crucial for the proof of the factorization. The definition given here together with the known description of ρ in terms of the solutions of nonlinear integral equations is useful for performing, e.g., the Trotter limit in the finite temperature case, or for obtaining numerical results for the correlation functions at short distances. We also address the issue of the construction of an exponential form of the density matrix for finite α.

Correlates of Sexual Functioning and Relationship Satisfaction Among Men and Women Experiencing Chronic Pain.

Science.gov (United States)

Finn, Erica; Morrison, Todd G; McGuire, Brian E

2018-05-01

The aims of the study were to 1) examine the prevalence of sexual functioning difficulties in a chronic pain sample; 2) identify correlates of sexual functioning and relationship satisfaction utilizing pain variables (pain severity and pain interference) and psychological variables (mood, pain-related cognitions, self-efficacy, self-esteem, body-image); and 3) investigate possible sex differences in the correlates of sexual functioning and relationship satisfaction. Two hundred sixty-nine participants were recruited online from chronic pain organizations, websites, social media sites, and discussion forums. Those who met criteria for inclusion were presented with a variety of measures related to pain, sexual functioning, and relationship satisfaction (for those in a relationship), as well as cognitive and affective variables. Participant mean age was 37 years, and the majority were female, heterosexual, and currently in a relationship. High levels of pain severity and interference from pain, fatigue, depression, anxiety, stress, and body image concerns were reported, along with low levels of self-esteem and pain self-efficacy. In addition, substantial proportions of male (43%) and female (48%) respondents had scores indicative of sexual problems. Exploratory hierarchical regression analyses revealed that, for women, age and relationship satisfaction (which were both treated as covariates) as well as depression emerged as statistically significant correlates of sexual functioning (i.e., women who were older and reported greater levels of depression and less satisfaction with their current relationship indicated poorer sexual functioning). When relationship satisfaction was the criterion measure, age and sexual functioning (again, treated as covariates) and perceived stress emerged as significant (i.e., women who were older, reported poorer sexual functioning, and reported greater perceived stress also indicated being less satisfied with their current relationship

Correlation functions of the energy-momentum tensor in SU(2) gauge theory at finite temperature

DEFF Research Database (Denmark)

Huebner, K.; Karsch, F.; Pica, Claudio

2008-01-01

We calculate correlation functions of the energy-momentum tensor in the vicinity of the deconfinement phase transition of (3+1)-dimensional SU(2) gauge theory and discuss their critical behavior in the vicinity of the second order deconfinement transition. We show that correlation functions...... of the trace of the energy momentum tensor diverge uniformly at the critical point in proportion to the specific heat singularity. Correlation functions of the pressure, on the other hand, stay finite at the critical point. We discuss the consequences of these findings for the analysis of transport...... coefficients, in particular the bulk viscosity, in the vicinity of a second order phase transition point....

Superconformal field theory in three dimensions: correlation functions of conserved currents

Energy Technology Data Exchange (ETDEWEB)

Buchbinder, Evgeny I.; Kuzenko, Sergei M.; Samsonov, Igor B. [School of Physics M013, The University of Western Australia,35 Stirling Highway, Crawley W.A. 6009 (Australia)

2015-06-22

For N-extended superconformal field theories in three spacetime dimensions (3D), with 1≤N≤3, we compute the two- and three-point correlation functions of the supercurrent and the flavour current multiplets. We demonstrate that supersymmetry imposes additional restrictions on the correlators of conserved currents as compared with the non-supersymmetric case studied by Osborn and Petkou in hep-th/9307010. It is shown that the three-point function of the supercurrent is determined by a single functional form consistent with the conservation equation and all the symmetry properties. Similarly, the three-point function of the flavour current multiplets is also determined by a single functional form in the N=1 and N=3 cases. The specific feature of the N=2 case is that two independent structures are allowed for the three-point function of flavour current multiplets, but only one of them contributes to the three-point function of the conserved currents contained in these multiplets. Since the supergravity and super-Yang-Mills Ward identities are expected to relate the coefficients of the two- and three-point functions under consideration, the results obtained for 3D superconformal field theory are analogous to those in 2D conformal field theory. In addition, we present a new supertwistor construction for compactified Minkowski superspace. It is suitable for developing superconformal field theory on 3D spacetimes other than Minkowski space, such as S{sup 1}×S{sup 2} and its universal covering space ℝ×S{sup 2}.

Dynamic Functional Connectivity States Between the Dorsal and Ventral Sensorimotor Networks Revealed by Dynamic Conditional Correlation Analysis of Resting-State Functional Magnetic Resonance Imaging.

Science.gov (United States)

Syed, Maleeha F; Lindquist, Martin A; Pillai, Jay J; Agarwal, Shruti; Gujar, Sachin K; Choe, Ann S; Caffo, Brian; Sair, Haris I

2017-12-01

Functional connectivity in resting-state functional magnetic resonance imaging (rs-fMRI) has received substantial attention since the initial findings of Biswal et al. Traditional network correlation metrics assume that the functional connectivity in the brain remains stationary over time. However, recent studies have shown that robust temporal fluctuations of functional connectivity among as well as within functional networks exist, challenging this assumption. In this study, these dynamic correlation differences were investigated between the dorsal and ventral sensorimotor networks by applying the dynamic conditional correlation model to rs-fMRI data of 20 healthy subjects. k-Means clustering was used to determine an optimal number of discrete connectivity states (k = 10) of the sensorimotor system across all subjects. Our analysis confirms the existence of differences in dynamic correlation between the dorsal and ventral networks, with highest connectivity found within the ventral motor network.

Correlation functions of electronic and nuclear spins in a Heisenberg antiferromagnet semi-infinite media

International Nuclear Information System (INIS)

Sarmento, E.F.

1980-01-01

Results are found for the correlation dynamic functions (or the correspondent green functions) between any combination including pairs of electronic anel nuclear spin operators in an antiferromagnet semi-infinite media., at low temperature T N . These correlation functions, are used to investigate, at the same time, the properties of surface spin waves in volume and surface. The dispersion relatons of nuclear and electronic spin waves coupled modes, in surface are found, resolving a system of linearized equatons of spin operators a system of linearized equations of spin operators. (author) [pt

Correlation function for density perturbations in an expanding universe. I. Linear theory

International Nuclear Information System (INIS)

McClelland, J.; Silk, J.

1977-01-01

We derive analytic solutions for the evolution of linearized adiabatic spherically symmetric density perturbations and the two-point correlation function in two regimes of the early universe: the radiation-dominated regime prior to decoupling, and the matter-dominated regime after decoupling. The solutions are for an Einstein--de Sitter universe, and include pressure effects. In the radiation era, we find that individual spherically symmetric adiabatic density perturbations smaller than the Jeans length flow outward like water waves instead of oscillating as infinite plane waves. It seems likely that the only primordial structures on scales smaller than the maximum Jeans length which could survive are very regular waves such as infinite plane waves. However, structure does build up in the correlation function over distances comparable with the maximum Jeans length in the radiation regime, and could lead to the eventual formation of galaxy superclusters. This scale (approx.10 17 Ω -2 M/sub sun)/therefore provides a natural dimension for large-scale structure arising out of the early universe. A general technique is described for constructing solutions for the evolution of the two-point correlation function, and applied to study white noise and power-law initial conditions for primordial inhomogeneities

T\\overline{T} -deformations, AdS/CFT and correlation functions

Science.gov (United States)

Giribet, Gaston

2018-02-01

A solvable irrelevant deformation of AdS3/CFT2 correspondence leading to a theory with Hagedorn spectrum at high energy has been recently proposed. It consists of a single trace deformation of the boundary theory, which is inspired by the recent work on solvable T\\overline{T} deformations of two-dimensional CFTs. Thought of as a worldsheet σ-model, the interpretation of the deformed theory from the bulk viewpoint is that of string theory on a background that interpolates between AdS3 in the IR and a linear dilaton vacuum of little string theory in the UV. The insertion of the operator that realizes the deformation in the correlation functions produces a logarithmic divergence, leading to the renormalization of the primary operators, which thus acquire an anomalous dimension. We compute this anomalous dimension explicitly, and this provides us with a direct way of determining the spectrum of the theory. We discuss this and other features of the correlation functions in presence of the deformation.

MN15-L: A New Local Exchange-Correlation Functional for Kohn-Sham Density Functional Theory with Broad Accuracy for Atoms, Molecules, and Solids.

Science.gov (United States)

Yu, Haoyu S; He, Xiao; Truhlar, Donald G

2016-03-08

Kohn-Sham density functional theory is widely used for applications of electronic structure theory in chemistry, materials science, and condensed-matter physics, but the accuracy depends on the quality of the exchange-correlation functional. Here, we present a new local exchange-correlation functional called MN15-L that predicts accurate results for a broad range of molecular and solid-state properties including main-group bond energies, transition metal bond energies, reaction barrier heights, noncovalent interactions, atomic excitation energies, ionization potentials, electron affinities, total atomic energies, hydrocarbon thermochemistry, and lattice constants of solids. The MN15-L functional has the same mathematical form as a previous meta-nonseparable gradient approximation exchange-correlation functional, MN12-L, but it is improved because we optimized it against a larger database, designated 2015A, and included smoothness restraints; the optimization has a much better representation of transition metals. The mean unsigned error on 422 chemical energies is 2.32 kcal/mol, which is the best among all tested functionals, with or without nonlocal exchange. The MN15-L functional also provides good results for test sets that are outside the training set. A key issue is that the functional is local (no nonlocal exchange or nonlocal correlation), which makes it relatively economical for treating large and complex systems and solids. Another key advantage is that medium-range correlation energy is built in so that one does not need to add damped dispersion by molecular mechanics in order to predict accurate noncovalent binding energies. We believe that the MN15-L functional should be useful for a wide variety of applications in chemistry, physics, materials science, and molecular biology.

Stochastic wave-function unravelling of the generalized Lindblad equation using correlated states

International Nuclear Information System (INIS)

Moodley, Mervlyn; Nsio Nzundu, T; Paul, S

2012-01-01

We perform a stochastic wave-function unravelling of the generalized Lindblad master equation using correlated states, a combination of the system state vectors and the environment population. The time-convolutionless projection operator method using correlated projection superoperators is applied to a two-state system, a qubit, that is coupled to an environment consisting of two energy bands which are both populated. These results are compared to the data obtained from Monte Carlo wave-function simulations based on the unravelling of the master equation. We also show a typical quantum trajectory and the average time evolution of the state vector on the Bloch sphere. (paper)

Nonequilibrium fluctuation-dissipation relations for one- and two-particle correlation functions in steady-state quantum transport

International Nuclear Information System (INIS)

Ness, H.; Dash, L. K.

2014-01-01

We study the non-equilibrium (NE) fluctuation-dissipation (FD) relations in the context of quantum thermoelectric transport through a two-terminal nanodevice in the steady-state. The FD relations for the one- and two-particle correlation functions are derived for a model of the central region consisting of a single electron level. Explicit expressions for the FD relations of the Green's functions (one-particle correlations) are provided. The FD relations for the current-current and charge-charge (two-particle) correlations are calculated numerically. We use self-consistent NE Green's functions calculations to treat the system in the absence and in the presence of interaction (electron-phonon) in the central region. We show that, for this model, there is no single universal FD theorem for the NE steady state. There are different FD relations for each different class of problems. We find that the FD relations for the one-particle correlation function are strongly dependent on both the NE conditions and the interactions, while the FD relations of the current-current correlation function are much less dependent on the interaction. The latter property suggests interesting applications for single-molecule and other nanoscale transport experiments

Fredholm determinant representation of quantum correlation function for Sine-Gordon at special value of coupling constant

International Nuclear Information System (INIS)

Itoyama, H.; Korepin, V.E.; Thacker, H.B.

1992-01-01

In this paper, correlation functions of the Sine-Gordon model (which is equivalent of the Massive-Thirring model) are considered at the free fermion point. The authors derive a determinant formula for local correlation functions of the Sine-Gordon model, starting form Bethe ansatz wave function. Kernel of integral operator is trigonometric version of the one for Impenetrable Bosons

Averages of ratios of the Riemann zeta-function and correlations of divisor sums

Science.gov (United States)

Conrey, Brian; Keating, Jonathan P.

2017-10-01

Nonlinearity has published articles containing a significant number-theoretic component since the journal was first established. We examine one thread, concerning the statistics of the zeros of the Riemann zeta function. We extend this by establishing a connection between the ratios conjecture for the Riemann zeta-function and a conjecture concerning correlations of convolutions of Möbius and divisor functions. Specifically, we prove that the ratios conjecture and an arithmetic correlations conjecture imply the same result. This provides new support for the ratios conjecture, which previously had been motivated by analogy with formulae in random matrix theory and by a heuristic recipe. Our main theorem generalises a recent calculation pertaining to the special case of two-over-two ratios.

Functional connectivity within and between intrinsic brain networks correlates with trait mind wandering.

Science.gov (United States)

Godwin, Christine A; Hunter, Michael A; Bezdek, Matthew A; Lieberman, Gregory; Elkin-Frankston, Seth; Romero, Victoria L; Witkiewitz, Katie; Clark, Vincent P; Schumacher, Eric H

2017-08-01

Individual differences across a variety of cognitive processes are functionally associated with individual differences in intrinsic networks such as the default mode network (DMN). The extent to which these networks correlate or anticorrelate has been associated with performance in a variety of circumstances. Despite the established role of the DMN in mind wandering processes, little research has investigated how large-scale brain networks at rest relate to mind wandering tendencies outside the laboratory. Here we examine the extent to which the DMN, along with the dorsal attention network (DAN) and frontoparietal control network (FPCN) correlate with the tendency to mind wander in daily life. Participants completed the Mind Wandering Questionnaire and a 5-min resting state fMRI scan. In addition, participants completed measures of executive function, fluid intelligence, and creativity. We observed significant positive correlations between trait mind wandering and 1) increased DMN connectivity at rest and 2) increased connectivity between the DMN and FPCN at rest. Lastly, we found significant positive correlations between trait mind wandering and fluid intelligence (Ravens) and creativity (Remote Associates Task). We interpret these findings within the context of current theories of mind wandering and executive function and discuss the possibility that certain instances of mind wandering may not be inherently harmful. Due to the controversial nature of global signal regression (GSReg) in functional connectivity analyses, we performed our analyses with and without GSReg and contrast the results from each set of analyses. Copyright © 2017 Elsevier Ltd. All rights reserved.

Total Correlation Function Integrals and Isothermal Compressibilities from Molecular Simulations

DEFF Research Database (Denmark)

Wedberg, Rasmus; Peters, Günther H.j.; Abildskov, Jens

2008-01-01

Generation of thermodynamic data, here compressed liquid density and isothermal compressibility data, using molecular dynamics simulations is investigated. Five normal alkane systems are simulated at three different state points. We compare two main approaches to isothermal compressibilities: (1...... in approximately the same amount of time. This suggests that computation of total correlation function integrals is a route to isothermal compressibility, as accurate and fast as well-established benchmark techniques. A crucial step is the integration of the radial distribution function. To obtain sensible results...

Communication: importance sampling including path correlation in semiclassical initial value representation calculations for time correlation functions.

Science.gov (United States)

Pan, Feng; Tao, Guohua

2013-03-07

Full semiclassical (SC) initial value representation (IVR) for time correlation functions involves a double phase space average over a set of two phase points, each of which evolves along a classical path. Conventionally, the two initial phase points are sampled independently for all degrees of freedom (DOF) in the Monte Carlo procedure. Here, we present an efficient importance sampling scheme by including the path correlation between the two initial phase points for the bath DOF, which greatly improves the performance of the SC-IVR calculations for large molecular systems. Satisfactory convergence in the study of quantum coherence in vibrational relaxation has been achieved for a benchmark system-bath model with up to 21 DOF.

Mark 4A DSN receiver-exciter and transmitter subsystems

Science.gov (United States)

Wick, M. R.

1986-01-01

The present configuration of the Mark 4A DSN Receiver-Exciter and Transmitter Subsystems is described. Functional requirements and key characteristics are given to show the differences in the capabilities required by the Networks Consolidation task for combined High Earth Orbiter and Deep Space Network tracking support.

Instantons: Dynamical mass generation, chiral ward identities and the topological charge correlation function

International Nuclear Information System (INIS)

McDougall, N.A.

1983-01-01

When dynamical mass generation resulting from the breakdown of chiral symmetry is taken into account, instanton dynamics treated within the dilute gas approximation may satisfy the constraints on the quark condensates and the topological charge correlation function derived by Crewther from an analysis of the chiral Ward identities assuming the absence of a physical axial U(1) Goldstone boson. From a consideration of the contribution of the eta' to the topological charge correlation function, a relationship is derived in which msub(eta') 2 fsub(eta') 2 is proportional to the vacuum energy density. (orig.)

Near-infrared branding efficiently correlates light and electron microscopy.

Science.gov (United States)

Bishop, Derron; Nikić, Ivana; Brinkoetter, Mary; Knecht, Sharmon; Potz, Stephanie; Kerschensteiner, Martin; Misgeld, Thomas

2011-06-05

The correlation of light and electron microscopy of complex tissues remains a major challenge. Here we report near-infrared branding (NIRB), which facilitates such correlation by using a pulsed, near-infrared laser to create defined fiducial marks in three dimensions in fixed tissue. As these marks are fluorescent and can be photo-oxidized to generate electron contrast, they can guide re-identification of previously imaged structures as small as dendritic spines by electron microscopy.

Development of field performance evaluation tools and program for pavement marking materials : technical report

Science.gov (United States)

2011-03-01

Historically the prequalification or selection of pavement marking materials (PMMs) is mainly based on : product specifications and lab testing, which do not correlate well with the field performance of the products. : On the other hand, there is no ...

Impact parameter and source selected correlation functions with a 4π multidetector

International Nuclear Information System (INIS)

Gourio, D.; Reposeur, T.; Assenard, M.; Germain, M.; Ardouin, D.; Eudes, P.; Lautridou, P.; Laville, J.L.; Lebrun, C.; Metivier, V.

1997-01-01

For the first time in the domain of (light charged) particle interferometry in nuclear physics, a complete study of proton an deuteron correlation functions is presented with both impact parameter and emission source selections. The correlations were determined for the system 129 Xe + nat Sn at 45 and 50 AMeV using the 4π multidetector INDRA at GANIL as an event selector as well as a particle correlator. Very short emission times are found for all the selections indicating possible contributions from a fast and preequilibrium process. (author)

Correlated binomial models and correlation structures

International Nuclear Information System (INIS)

Hisakado, Masato; Kitsukawa, Kenji; Mori, Shintaro

2006-01-01

We discuss a general method to construct correlated binomial distributions by imposing several consistent relations on the joint probability function. We obtain self-consistency relations for the conditional correlations and conditional probabilities. The beta-binomial distribution is derived by a strong symmetric assumption on the conditional correlations. Our derivation clarifies the 'correlation' structure of the beta-binomial distribution. It is also possible to study the correlation structures of other probability distributions of exchangeable (homogeneous) correlated Bernoulli random variables. We study some distribution functions and discuss their behaviours in terms of their correlation structures

Logarithmic two-point correlation functions from a z=2 Lifshitz model

International Nuclear Information System (INIS)

Zingg, T.

2014-01-01

The Einstein-Proca action is known to have asymptotically locally Lifshitz spacetimes as classical solutions. For dynamical exponent z=2, two-point correlation functions for fluctuations around such a geometry are derived analytically. It is found that the retarded correlators are stable in the sense that all quasinormal modes are situated in the lower half-plane of complex frequencies. Correlators in the longitudinal channel exhibit features that are reminiscent of a structure usually obtained in field theories that are logarithmic, i.e. contain an indecomposable but non-diagonalizable highest weight representation. This provides further evidence for conjecturing the model at hand as a candidate for a gravity dual of a logarithmic field theory with anisotropic scaling symmetry

Neural correlates of emotional personality: a structural and functional magnetic resonance imaging study.

Directory of Open Access Journals (Sweden)

Stefan Koelsch

Full Text Available Studies addressing brain correlates of emotional personality have remained sparse, despite the involvement of emotional personality in health and well-being. This study investigates structural and functional brain correlates of psychological and physiological measures related to emotional personality. Psychological measures included neuroticism, extraversion, and agreeableness scores, as assessed using a standard personality questionnaire. As a physiological measure we used a cardiac amplitude signature, the so-called E κ value (computed from the electrocardiogram which has previously been related to tender emotionality. Questionnaire scores and E κ values were related to both functional (eigenvector centrality mapping, ECM and structural (voxel-based morphometry, VBM neuroimaging data. Functional magnetic resonance imaging (fMRI data were obtained from 22 individuals (12 females while listening to music (joy, fear, or neutral music. ECM results showed that agreeableness scores correlated with centrality values in the dorsolateral prefrontal cortex, the anterior cingulate cortex, and the ventral striatum (nucleus accumbens. Individuals with higher E κ values (indexing higher tender emotionality showed higher centrality values in the subiculum of the right hippocampal formation. Structural MRI data from an independent sample of 59 individuals (34 females showed that neuroticism scores correlated with volume of the left amygdaloid complex. In addition, individuals with higher E κ showed larger gray matter volume in the same portion of the subiculum in which individuals with higher E κ showed higher centrality values. Our results highlight a role of the amygdala in neuroticism. Moreover, they indicate that a cardiac signature related to emotionality (E κ correlates with both function (increased network centrality and structure (grey matter volume of the subiculum of the hippocampal formation, suggesting a role of the hippocampal formation for

Neural correlates of emotional personality: a structural and functional magnetic resonance imaging study.

Science.gov (United States)

Koelsch, Stefan; Skouras, Stavros; Jentschke, Sebastian

2013-01-01

Studies addressing brain correlates of emotional personality have remained sparse, despite the involvement of emotional personality in health and well-being. This study investigates structural and functional brain correlates of psychological and physiological measures related to emotional personality. Psychological measures included neuroticism, extraversion, and agreeableness scores, as assessed using a standard personality questionnaire. As a physiological measure we used a cardiac amplitude signature, the so-called E κ value (computed from the electrocardiogram) which has previously been related to tender emotionality. Questionnaire scores and E κ values were related to both functional (eigenvector centrality mapping, ECM) and structural (voxel-based morphometry, VBM) neuroimaging data. Functional magnetic resonance imaging (fMRI) data were obtained from 22 individuals (12 females) while listening to music (joy, fear, or neutral music). ECM results showed that agreeableness scores correlated with centrality values in the dorsolateral prefrontal cortex, the anterior cingulate cortex, and the ventral striatum (nucleus accumbens). Individuals with higher E κ values (indexing higher tender emotionality) showed higher centrality values in the subiculum of the right hippocampal formation. Structural MRI data from an independent sample of 59 individuals (34 females) showed that neuroticism scores correlated with volume of the left amygdaloid complex. In addition, individuals with higher E κ showed larger gray matter volume in the same portion of the subiculum in which individuals with higher E κ showed higher centrality values. Our results highlight a role of the amygdala in neuroticism. Moreover, they indicate that a cardiac signature related to emotionality (E κ) correlates with both function (increased network centrality) and structure (grey matter volume) of the subiculum of the hippocampal formation, suggesting a role of the hippocampal formation for

Low-temperature expansions and correlation functions of the Z3-chiral Potts model

International Nuclear Information System (INIS)

Han, N.S.; Honecker, A.

1993-04-01

Using perturbative methods we derive new results for the spectrum and correlation functions of the general Z 3 -chiral Potts quantum chain in the massive low-temperature phase. Explicit calculations of the ground state energy and the first excitations in the zero momentum sector give excellent approximations and confirm the general statement that the spectrum in the low-temperature phase of general Z n -spin quantum chains is identical to one in the high-temperature phase where the role of charge and boundary conditions are interchanged. Using a perturbative expansion of the ground state for the Z 3 model we are able to gain some insight in correlation functions. We argue that they might be oscillating and give estimates for the oscillation length as well as the correlation length. (orig.)

Imaging the square of the correlated two-electron wave function of a hydrogen molecule.

Science.gov (United States)

Waitz, M; Bello, R Y; Metz, D; Lower, J; Trinter, F; Schober, C; Keiling, M; Lenz, U; Pitzer, M; Mertens, K; Martins, M; Viefhaus, J; Klumpp, S; Weber, T; Schmidt, L Ph H; Williams, J B; Schöffler, M S; Serov, V V; Kheifets, A S; Argenti, L; Palacios, A; Martín, F; Jahnke, T; Dörner, R

2017-12-22

The toolbox for imaging molecules is well-equipped today. Some techniques visualize the geometrical structure, others the electron density or electron orbitals. Molecules are many-body systems for which the correlation between the constituents is decisive and the spatial and the momentum distribution of one electron depends on those of the other electrons and the nuclei. Such correlations have escaped direct observation by imaging techniques so far. Here, we implement an imaging scheme which visualizes correlations between electrons by coincident detection of the reaction fragments after high energy photofragmentation. With this technique, we examine the H 2 two-electron wave function in which electron-electron correlation beyond the mean-field level is prominent. We visualize the dependence of the wave function on the internuclear distance. High energy photoelectrons are shown to be a powerful tool for molecular imaging. Our study paves the way for future time resolved correlation imaging at FELs and laser based X-ray sources.

Three-point correlation functions of giant magnons with finite size

International Nuclear Information System (INIS)

Ahn, Changrim; Bozhilov, Plamen

2011-01-01

We compute holographic three-point correlation functions or structure constants of a zero-momentum dilaton operator and two (dyonic) giant magnon string states with a finite-size length in the semiclassical approximation. We show that the semiclassical structure constants match exactly with the three-point functions between two su(2) magnon single trace operators with finite size and the Lagrangian in the large 't Hooft coupling constant limit. A special limit J>>√(λ) of our result is compared with the relevant result based on the Luescher corrections.

Electron-hydrogen atom inelastic scattering through a correlated wave function

International Nuclear Information System (INIS)

Serpa Vieira, A.E. de.

1984-01-01

The inelastic collision between an electron and a hydrogen atom is studied. A correlated function, used previously to the same system in elastic collisions in which there are two parameters fitted in the energy range studied, is utilized. With this functions an equation is developed for the direct and exchange transition matrix elements to the 15-25 and 15-2 p transitions. The obtained results are compared with Willians experimental measurements, as well the results given by the theoretical treatments of Kingston, Fon and Burke. (L.C.) [pt

Multimodal Investigation of Network Level Effects Using Intrinsic Functional Connectivity, Anatomical Covariance, and Structure-to-Function Correlations in Unmedicated Major Depressive Disorder.

Science.gov (United States)

Scheinost, Dustin; Holmes, Sophie E; DellaGioia, Nicole; Schleifer, Charlie; Matuskey, David; Abdallah, Chadi G; Hampson, Michelle; Krystal, John H; Anticevic, Alan; Esterlis, Irina

2018-04-01

Converging evidence suggests that major depressive disorder (MDD) affects multiple large-scale brain networks. Analyses of the correlation or covariance of regional brain structure and function applied to structural and functional MRI data may provide insights into systems-level organization and structure-to-function correlations in the brain in MDD. This study applied tensor-based morphometry and intrinsic connectivity distribution to identify regions of altered volume and intrinsic functional connectivity in data from unmedicated individuals with MDD (n=17) and healthy comparison participants (HC, n=20). These regions were then used as seeds for exploratory anatomical covariance and connectivity analyses. Reduction in volume in the anterior cingulate cortex (ACC) and lower structural covariance between the ACC and the cerebellum were observed in the MDD group. Additionally, individuals with MDD had significantly lower whole-brain intrinsic functional connectivity in the medial prefrontal cortex (mPFC). This mPFC region showed altered connectivity to the ventral lateral PFC (vlPFC) and local circuitry in MDD. Global connectivity in the ACC was negatively correlated with reported depressive symptomatology. The mPFC-vlPFC connectivity was positively correlated with depressive symptoms. Finally, we observed increased structure-to-function correlation in the PFC/ACC in the MDD group. Although across all analysis methods and modalities alterations in the PFC/ACC were a common finding, each modality and method detected alterations in subregions belonging to distinct large-scale brain networks. These exploratory results support the hypothesis that MDD is a systems level disorder affecting multiple brain networks located in the PFC and provide new insights into the pathophysiology of this disorder.

Multimodal Investigation of Network Level Effects Using Intrinsic Functional Connectivity, Anatomical Covariance, and Structure-to-Function Correlations in Unmedicated Major Depressive Disorder

Science.gov (United States)

Scheinost, Dustin; Holmes, Sophie E; DellaGioia, Nicole; Schleifer, Charlie; Matuskey, David; Abdallah, Chadi G; Hampson, Michelle; Krystal, John H; Anticevic, Alan; Esterlis, Irina

2018-01-01

Converging evidence suggests that major depressive disorder (MDD) affects multiple large-scale brain networks. Analyses of the correlation or covariance of regional brain structure and function applied to structural and functional MRI data may provide insights into systems-level organization and structure-to-function correlations in the brain in MDD. This study applied tensor-based morphometry and intrinsic connectivity distribution to identify regions of altered volume and intrinsic functional connectivity in data from unmedicated individuals with MDD (n=17) and healthy comparison participants (HC, n=20). These regions were then used as seeds for exploratory anatomical covariance and connectivity analyses. Reduction in volume in the anterior cingulate cortex (ACC) and lower structural covariance between the ACC and the cerebellum were observed in the MDD group. Additionally, individuals with MDD had significantly lower whole-brain intrinsic functional connectivity in the medial prefrontal cortex (mPFC). This mPFC region showed altered connectivity to the ventral lateral PFC (vlPFC) and local circuitry in MDD. Global connectivity in the ACC was negatively correlated with reported depressive symptomatology. The mPFC–vlPFC connectivity was positively correlated with depressive symptoms. Finally, we observed increased structure-to-function correlation in the PFC/ACC in the MDD group. Although across all analysis methods and modalities alterations in the PFC/ACC were a common finding, each modality and method detected alterations in subregions belonging to distinct large-scale brain networks. These exploratory results support the hypothesis that MDD is a systems level disorder affecting multiple brain networks located in the PFC and provide new insights into the pathophysiology of this disorder. PMID:28944772

Reduced density matrix embedding. General formalism and inter-domain correlation functional.

Science.gov (United States)

Pernal, Katarzyna

2016-08-03

An embedding method for a one-electron reduced density matrix (1-RDM) is proposed. It is based on partitioning of 1-RDM into domains and describing each domain in the effective potential of the other ones. To assure N-representability of the total 1-RDM N-representability and strong-orthogonality conditions are imposed on the domains. The total energy is given as a sum of single-domain energies and domain-domain electron interaction contributions. Higher than two-body inter-domain interaction terms are neglected. The two-body correlation terms are approximated by deriving inter-domain correlation from couplings of density fluctuations of two domains at a time. Unlike in most density embedding methods kinetic energy is treated exactly and it is not required that densities pertaining to the domains are only weakly overlapping. We propose to treat each domain by a corrected perfect-pairing functional. On a few examples it is shown that the embedding reduced density matrix functional method (ERDMF) yields excellent results for molecules that are well described by a single Lewis structure even if strong static intra-domain or dynamic inter-domain correlation effects must be accounted for.

Functional connectivity and structural covariance between regions of interest can be measured more accurately using multivariate distance correlation.

Science.gov (United States)

Geerligs, Linda; Cam-Can; Henson, Richard N

2016-07-15

Studies of brain-wide functional connectivity or structural covariance typically use measures like the Pearson correlation coefficient, applied to data that have been averaged across voxels within regions of interest (ROIs). However, averaging across voxels may result in biased connectivity estimates when there is inhomogeneity within those ROIs, e.g., sub-regions that exhibit different patterns of functional connectivity or structural covariance. Here, we propose a new measure based on "distance correlation"; a test of multivariate dependence of high dimensional vectors, which allows for both linear and non-linear dependencies. We used simulations to show how distance correlation out-performs Pearson correlation in the face of inhomogeneous ROIs. To evaluate this new measure on real data, we use resting-state fMRI scans and T1 structural scans from 2 sessions on each of 214 participants from the Cambridge Centre for Ageing & Neuroscience (Cam-CAN) project. Pearson correlation and distance correlation showed similar average connectivity patterns, for both functional connectivity and structural covariance. Nevertheless, distance correlation was shown to be 1) more reliable across sessions, 2) more similar across participants, and 3) more robust to different sets of ROIs. Moreover, we found that the similarity between functional connectivity and structural covariance estimates was higher for distance correlation compared to Pearson correlation. We also explored the relative effects of different preprocessing options and motion artefacts on functional connectivity. Because distance correlation is easy to implement and fast to compute, it is a promising alternative to Pearson correlations for investigating ROI-based brain-wide connectivity patterns, for functional as well as structural data. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Evaluation of time correlation functions from a generalized Enskog equation

Energy Technology Data Exchange (ETDEWEB)

Yip, S.; Alley, W.E.; Alder, B.J.

1982-01-01

Numerical results for the density and current correlation functions in dense hard-shape fluids are obtained from a kinetic equation which is the extension of the linearized Enskog equation to finite wavelengths in order to demonstrate the convergence of the method of solution. Comparison is made to a previously proposed approximate solution.

Evaluation of time correlation functions from a generalized Enskog equation

International Nuclear Information System (INIS)

Yip, S.; Alley, W.E.; Alder, B.J.

1982-01-01

Numerical results for the density and current correlation functions in dense hard-shape fluids are obtained from a kinetic equation which is the extension of the linearized Enskog equation to finite wavelengths in order to demonstrate the convergence of the method of solution. Comparison is made to a previously proposed approximate solution

Cognitive functioning in bilateral perisylvian polymicrogyria (BPP): clinical and radiological correlations.

Science.gov (United States)

Jansen, An C; Leonard, Gabriel; Bastos, Alexandre C; Esposito-Festen, Josée E; Tampieri, Donatella; Watkins, Kate; Andermann, Frederick; Andermann, Eva

2005-05-01

Bilateral perisylvian polymicrogyria (BPP) is a malformation of cortical development, frequently associated with severe dysarthria or anarthria. BPP patients are therefore often labeled as severely retarded, but a detailed neuropsychological profile has not been reported to date. In a series of 14 patients, we demonstrated that only a minority had extremely low intelligence, and that some aspects of cognitive function correlated with the extent of the cortical disorganization. Early age at seizure onset correlated positively with Performance IQ scores (PBPP are more likely to have early seizure onset, resulting in greater interference with ongoing cognitive development. Receptive and expressive language skills were found to be equally poor. Frontal lobe function and memory abilities were relatively well preserved, suggesting that the observed cognitive profiles were related, at least in part, to specific areas of cortical dysfunction and not only to global dysfunction.

IGF-1 levels are significantly correlated with patient-reported measures of sexual function.

Science.gov (United States)

Pastuszak, A W; Liu, J S; Vij, A; Mohamed, O; Sathyamoorthy, K; Lipshultz, L I; Khera, M

2011-01-01

Growth hormone (GH) supplementation may help to preserve erectile function. We assessed whether serum insulin-like growth factor 1 (IGF-1) levels, a surrogate for GH levels, correlate with sexual function scores in 65 men who completed the Sexual Health Inventory for Men (SHIM) and Expanded Prostate Cancer Index Composite (EPIC) questionnaires, and had serum IGF-1 and testosterone levels determined. Median±s.d. IGF-1 level, SHIM and EPIC scores were 235.0±86.4, 19.5±8.7 and 56.4±28.3 mg ml(-1), respectively. IGF-1 levels and total SHIM score correlate significantly (r=0.31, P=0.02), as do IGF-1 levels and all individual SHIM question scores, and IGF-1 levels and the sexual domain of the EPIC questionnaire (r=0.30, P=0.02). No correlation was observed between IGF-1 levels and Gleason score, IGF-1 and testosterone level or SHIM score and testosterone level. These data support a potential role for the GH axis in erectile function.

Correlation energy functional within the GW -RPA: Exact forms, approximate forms, and challenges

Science.gov (United States)

Ismail-Beigi, Sohrab

2010-05-01

In principle, the Luttinger-Ward Green’s-function formalism allows one to compute simultaneously the total energy and the quasiparticle band structure of a many-body electronic system from first principles. We present approximate and exact expressions for the correlation energy within the GW -random-phase approximation that are more amenable to computation and allow for developing efficient approximations to the self-energy operator and correlation energy. The exact form is a sum over differences between plasmon and interband energies. The approximate forms are based on summing over screened interband transitions. We also demonstrate that blind extremization of such functionals leads to unphysical results: imposing physical constraints on the allowed solutions (Green’s functions) is necessary. Finally, we present some relevant numerical results for atomic systems.

Linearized semiclassical initial value time correlation functions with maximum entropy analytic continuation.

Science.gov (United States)

Liu, Jian; Miller, William H

2008-09-28

The maximum entropy analytic continuation (MEAC) method is used to extend the range of accuracy of the linearized semiclassical initial value representation (LSC-IVR)/classical Wigner approximation for real time correlation functions. LSC-IVR provides a very effective "prior" for the MEAC procedure since it is very good for short times, exact for all time and temperature for harmonic potentials (even for correlation functions of nonlinear operators), and becomes exact in the classical high temperature limit. This combined MEAC+LSC/IVR approach is applied here to two highly nonlinear dynamical systems, a pure quartic potential in one dimensional and liquid para-hydrogen at two thermal state points (25 and 14 K under nearly zero external pressure). The former example shows the MEAC procedure to be a very significant enhancement of the LSC-IVR for correlation functions of both linear and nonlinear operators, and especially at low temperature where semiclassical approximations are least accurate. For liquid para-hydrogen, the LSC-IVR is seen already to be excellent at T=25 K, but the MEAC procedure produces a significant correction at the lower temperature (T=14 K). Comparisons are also made as to how the MEAC procedure is able to provide corrections for other trajectory-based dynamical approximations when used as priors.

Yang-Mills correlation functions from integrable spin chains

International Nuclear Information System (INIS)

Roiban, Radu; Volovich, Anastasia

2004-01-01

The relation between the dilatation operator of N = 4 Yang-Mills theory and integrable spin chains makes it possible to compute the one-loop anomalous dimensions of all operators in the theory. In this paper we show how to apply the technology of integrable spin chains to the calculation of Yang-Mills correlation functions by expressing them in terms of matrix elements of spin operators on the corresponding spin chain. We illustrate this method with several examples in the SU(2) sector described by the XXX 1/2 chain. (author)

Effect of ventricular function and volumes on exercise capacity in adults with repaired Tetralogy of Fallot

Directory of Open Access Journals (Sweden)

Natalia Dłużniewska

2018-01-01

Conclusion: Exercise intolerance in adults with repaired ToF is markedly depressed. The decreased exercise capacity is correlated with impaired RV function and may be associated also with LV dysfunction, which suggests right-to-left ventricular interaction.

Brain functional networks. Correlation analysis with clinical indexes in patients with diabetic retinopathy

Energy Technology Data Exchange (ETDEWEB)

Dai, Hui; Zhang, Yu; Hu, Su; Wang, Ximing; Li, Yonggang; Hu, Chunhong [The First Affiliated Hospital of Soochow University, Department of Radiology, Suzhou, Jiangsu (China); Lai, Lillian [LAC+USC Medical Center, Department of Neuroradiology, Los Angeles, CA (United States); Shen, Hailin [Suzhou Kowloon Hospital, Shanghai Jiao Tong University Medical School, Department of Radiology, Suzhou, Jiangsu (China)

2017-11-15

The relationship between parameters of brain functional networks and clinical indexes is unclear so far in patients with diabetic retinopathy (DR). This paper is to investigate this. Twenty-one patients with different grades of DR and 21 age- and sex-matched healthy controls were enrolled from August 2012 to September 2014. The clinical indexes recorded included DR grade, duration of diabetes, HbA1c, diabetic foot screen, fasting plasma glucose, insulin, Homa-β, Homa-IR, insulin sensitive index (ISI), Mini-Mental State Examination (MMSE), and patient sex and age. Subjects were scanned using 3-T MR with blood-oxygen-level-dependent and 3D-FSPGR sequences. MR data was analyzed via preprocessing and functional network construction, and quantified indexes of network (clustering coefficient, characteristic path length, global efficiency, degree distribution, and small worldness) were evaluated. Statistics consisted of ANOVA and correlation. There were significant differences between patients and controls among clustering coefficient, characteristic path length, degree distribution, and small worldness parameters (P < 0.05). MMSE scores negatively correlated with characteristic path length, and Hb1Ac negatively correlated with small worldness. MMSE, duration of diabetes, diabetic foot screen, fasting plasma glucose, insulin, Homa-β, Homa-IR, ISI, DR grade, and patient age, except from Hb1Ac, correlated with degree distribution in certain brain areas. Brain functional networks are altered, specifically in the areas of visual function and cognition, and these alterations may reflect the severity of visual weakness and cognitive decline in DR patients. Moreover, the brain networks may be affected both by long-standing and instant clinical factors. (orig.)

Brain functional networks. Correlation analysis with clinical indexes in patients with diabetic retinopathy

International Nuclear Information System (INIS)

Dai, Hui; Zhang, Yu; Hu, Su; Wang, Ximing; Li, Yonggang; Hu, Chunhong; Lai, Lillian; Shen, Hailin

2017-01-01

The relationship between parameters of brain functional networks and clinical indexes is unclear so far in patients with diabetic retinopathy (DR). This paper is to investigate this. Twenty-one patients with different grades of DR and 21 age- and sex-matched healthy controls were enrolled from August 2012 to September 2014. The clinical indexes recorded included DR grade, duration of diabetes, HbA1c, diabetic foot screen, fasting plasma glucose, insulin, Homa-β, Homa-IR, insulin sensitive index (ISI), Mini-Mental State Examination (MMSE), and patient sex and age. Subjects were scanned using 3-T MR with blood-oxygen-level-dependent and 3D-FSPGR sequences. MR data was analyzed via preprocessing and functional network construction, and quantified indexes of network (clustering coefficient, characteristic path length, global efficiency, degree distribution, and small worldness) were evaluated. Statistics consisted of ANOVA and correlation. There were significant differences between patients and controls among clustering coefficient, characteristic path length, degree distribution, and small worldness parameters (P < 0.05). MMSE scores negatively correlated with characteristic path length, and Hb1Ac negatively correlated with small worldness. MMSE, duration of diabetes, diabetic foot screen, fasting plasma glucose, insulin, Homa-β, Homa-IR, ISI, DR grade, and patient age, except from Hb1Ac, correlated with degree distribution in certain brain areas. Brain functional networks are altered, specifically in the areas of visual function and cognition, and these alterations may reflect the severity of visual weakness and cognitive decline in DR patients. Moreover, the brain networks may be affected both by long-standing and instant clinical factors. (orig.)

Correlations between respiratory and functional variables in heart failure

Directory of Open Access Journals (Sweden)

Fábio Cangeri Di Naso

2009-09-01

Full Text Available Background: Respiratory alterations can impact on the functional performance of patients with heart failure. Aim: To correlate maximum inspiratory muscular force and lung function variables with functional capacity in heart failure patients. Methods: A transversal study January-July 2007 with 42 chronic heart disease patients (28 males with no prior pulmonary illness. The patients were in New York Heart Association Functional Class I, II and III. The variables used were maximum inspiratory pressure, forced vital capacity and forced expiratory volume in the first second. Respiratory variables measured were distance covered in the six-minute walk test, NYHA functional class and the physical functioning domain of the Short Form-36 Quality of Life Questionnaire. Results: Maximum inspiratory pressure correlated with the six-minute walk test (r = 0.543 and p < 0.001, functional capacity (r = −0.566 and p < 0.001 and the physical functioning domain score of the Short Form-36 (r = 0.459 and p = 0.002. The same was true of forced vital capacity and the six-minute walk test (r = 0.501 and p = 0.001, functional capacity (r = −0.477 and p = 0.001 and Short Form-36 (r = 0.314 and p = 0.043 variables. Forced expiratory volume correlated with the distance covered in the six-minute walk test (r = 0.514 and p < 0.001 and functional capacity (r = −0.383 and p = 0.012. Conclusion: Lung function and inspiratory muscular force respiratory variables correlated with functional variables in patients with heart failure. Resumo: Fundamento: Alterações respiratórias podem influenciar o desempenho funcional em doentes com insuficiência cardíaca (IC. Objectivo: Correlacionar a força muscular inspiratória máxima (PImax e as variáveis da função pulmonar com a capacidade funcional em doentes com IC. Métodos: Estudo transversal

HD CAG-correlated gene expression changes support a simple dominant gain of function

Science.gov (United States)

Jacobsen, Jessie C.; Gregory, Gillian C.; Woda, Juliana M.; Thompson, Morgan N.; Coser, Kathryn R.; Murthy, Vidya; Kohane, Isaac S.; Gusella, James F.; Seong, Ihn Sik; MacDonald, Marcy E.; Shioda, Toshi; Lee, Jong-Min

2011-01-01

Huntington's disease is initiated by the expression of a CAG repeat-encoded polyglutamine region in full-length huntingtin, with dominant effects that vary continuously with CAG size. The mechanism could involve a simple gain of function or a more complex gain of function coupled to a loss of function (e.g. dominant negative-graded loss of function). To distinguish these alternatives, we compared genome-wide gene expression changes correlated with CAG size across an allelic series of heterozygous CAG knock-in mouse embryonic stem (ES) cell lines (HdhQ20/7, HdhQ50/7, HdhQ91/7, HdhQ111/7), to genes differentially expressed between Hdhex4/5/ex4/5 huntingtin null and wild-type (HdhQ7/7) parental ES cells. The set of 73 genes whose expression varied continuously with CAG length had minimal overlap with the 754-member huntingtin-null gene set but the two were not completely unconnected. Rather, the 172 CAG length-correlated pathways and 238 huntingtin-null significant pathways clustered into 13 shared categories at the network level. A closer examination of the energy metabolism and the lipid/sterol/lipoprotein metabolism categories revealed that CAG length-correlated genes and huntingtin-null-altered genes either were different members of the same pathways or were in unique, but interconnected pathways. Thus, varying the polyglutamine size in full-length huntingtin produced gene expression changes that were distinct from, but related to, the effects of lack of huntingtin. These findings support a simple gain-of-function mechanism acting through a property of the full-length huntingtin protein and point to CAG-correlative approaches to discover its effects. Moreover, for therapeutic strategies based on huntingtin suppression, our data highlight processes that may be more sensitive to the disease trigger than to decreased huntingtin levels. PMID:21536587

Simulation-based computation of the workload correlation function in a Levy-driven queue

NARCIS (Netherlands)

P. Glynn; M.R.H. Mandjes (Michel)

2009-01-01

htmlabstractIn this paper we consider a single-server queue with Levy input, and in particular its workload process (Q_t), focusing on its correlation structure. With the correlation function defined as r(t) := Cov(Q_0, Q_t)/Var Q_0 (assuming the workload process is in stationarity at time 0), we

Twist operator correlation functions in O(n) loop models

International Nuclear Information System (INIS)

Simmons, Jacob J H; Cardy, John

2009-01-01

Using conformal field theoretic methods we calculate correlation functions of geometric observables in the loop representation of the O(n) model at the critical point. We focus on correlation functions containing twist operators, combining these with anchored loops, boundaries with SLE processes and with double SLE processes. We focus further upon n = 0, representing self-avoiding loops, which corresponds to a logarithmic conformal field theory (LCFT) with c = 0. In this limit the twist operator plays the role of a 0-weight indicator operator, which we verify by comparison with known examples. Using the additional conditions imposed by the twist operator null states, we derive a new explicit result for the probabilities that an SLE 8/3 winds in various ways about two points in the upper half-plane, e.g. that the SLE passes to the left of both points. The collection of c = 0 logarithmic CFT operators that we use deriving the winding probabilities is novel, highlighting a potential incompatibility caused by the presence of two distinct logarithmic partners to the stress tensor within the theory. We argue that both partners do appear in the theory, one in the bulk and one on the boundary and that the incompatibility is resolved by restrictive bulk-boundary fusion rules

Intraoperative Frontal Alpha-Band Power Correlates with Preoperative Neurocognitive Function in Older Adults

Directory of Open Access Journals (Sweden)

Charles M. Giattino

2017-05-01

Full Text Available Each year over 16 million older Americans undergo general anesthesia for surgery, and up to 40% develop postoperative delirium and/or cognitive dysfunction (POCD. Delirium and POCD are each associated with decreased quality of life, early retirement, increased 1-year mortality, and long-term cognitive decline. Multiple investigators have thus suggested that anesthesia and surgery place severe stress on the aging brain, and that patients with less ability to withstand this stress will be at increased risk for developing postoperative delirium and POCD. Delirium and POCD risk are increased in patients with lower preoperative cognitive function, yet preoperative cognitive function is not routinely assessed, and no intraoperative physiological predictors have been found that correlate with lower preoperative cognitive function. Since general anesthesia causes alpha-band (8–12 Hz electroencephalogram (EEG power to decrease occipitally and increase frontally (known as “anteriorization”, and anesthetic-induced frontal alpha power is reduced in older adults, we hypothesized that lower intraoperative frontal alpha power might correlate with lower preoperative cognitive function. Here, we provide evidence that such a correlation exists, suggesting that lower intraoperative frontal alpha power could be used as a physiological marker to identify older adults with lower preoperative cognitive function. Lower intraoperative frontal alpha power could thus be used to target these at-risk patients for possible therapeutic interventions to help prevent postoperative delirium and POCD, or for increased postoperative monitoring and follow-up. More generally, these results suggest that understanding interindividual differences in how the brain responds to anesthetic drugs can be used as a probe of neurocognitive function (and dysfunction, and might be a useful measure of neurocognitive function in older adults.

Correlation functions in unitary minimal Liouville gravity and Frobenius manifolds

Energy Technology Data Exchange (ETDEWEB)

Belavin, V. [I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky prospect 53, 119991 Moscow (Russian Federation); Department of Quantum Physics, Institute for Information Transmission Problems,Bolshoy Karetny per. 19, 127994 Moscow (Russian Federation); Department of Theoretical Physics, National Research Nuclear University MEPhI,Kashirskoe shosse 31, 115409 Moscow (Russian Federation)

2015-02-10

We continue to study minimal Liouville gravity (MLG) using a dual approach based on the idea that the MLG partition function is related to the tau function of the A{sub q} integrable hierarchy via the resonance transformations, which are in turn fixed by conformal selection rules. One of the main problems in this approach is to choose the solution of the Douglas string equation that is relevant for MLG. The appropriate solution was recently found using connection with the Frobenius manifolds. We use this solution to investigate three- and four-point correlators in the unitary MLG models. We find an agreement with the results of the original approach in the region of the parameters where both methods are applicable. In addition, we find that only part of the selection rules can be satisfied using the resonance transformations. The physical meaning of the nonzero correlators, which before coupling to Liouville gravity are forbidden by the selection rules, and also the modification of the dual formulation that takes this effect into account remains to be found.

Long-distance behavior of temperature correlation functions in the one-dimensional Bose gas

Energy Technology Data Exchange (ETDEWEB)

Kozlowski, K.K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Maillet, J.M. [UMR 5672 du CNRS, ENS Lyon (France). Lab. de Physique; Slavnov, N.A. [Steklov Mathematical Institute, Moscow (Russian Federation)

2010-12-15

We describe a Bethe ansatz based method to derive, starting from a multiple integral representation, the long-distance asymptotic behavior at finite temperature of the density-density correlation function in the interacting onedimensional Bose gas. We compute the correlation lengths in terms of solutions of non-linear integral equations of the thermodynamic Bethe ansatz type. Finally, we establish a connection between the results obtained in our approach with the correlation lengths stemming from the quantum transfer matrix method. (orig.)

Correlation function measurement of uranium casting driven by tagged DT neutrons

International Nuclear Information System (INIS)

Li Jiansheng; Ye Cenming; Xie Wenxiong; Huang Po; Zeng Liheng; Jin Yu; Xie Qilin; Zhang Yi

2013-01-01

Background: In the nuclear disarmament process, the measurement and verification of uranium casting in sealed container are important to process control and treaty implementation. It is a difficult and hot problem to verify uranium casting in a sealed metal container, due to the weak intensity of neutron and gamma rays of uranium. Purpose: We want to measure the correlation functions of different casting in uranium casting verifications. Methods: Two BC501 scintillation detectors are placed outside the tagged neutron cone and in opposite position. The α detector forms the first channel pulse signal, while the two BC501 scintillation detectors form the second and third channel pulse signals. Those three pulsed time series are recorded by high speed acquisition system. The correlation functions between these signals are calculated by the time series. Results: Putting the two BC501 detectors into the tagged neutron cone, the time of flight for the 14 MeV neutron is measured. The FWHM in TOF spectrum is 2.0 ns. Putting the two BC501 detectors outside the tagged neutron cone, the correlation functions measured by high speed acquisition system and MCA are consistent. The spontaneous neutron decay constants of the castings are measured by γ rays. The decay constant of 6.5 kg Pb component is 184 μs -1 . The decay constants of 4 kg and 15 kg HEU casting are 210 μs -1 and 128 μs -1 , respectively. The correlation functions C 12 (τ), C 13 (τ) and C 23 (τ) are acquired. In C 12 (C), the γ ray peak coming from the inelastic reaction of 14-MeV neutrons with the casting is 5.0 ns before the neutron peak of fission chain. This time difference can estimate the casting position in container. The integrations of the C 12 (τ), C 13 (τ) and C 23 (τ) increase with the casting mass. The C 23 (τ) values of Pb component and DU casting are far less than the values of HEU casting. The C 23 (τ) integration of Pb component is 3.0% comparing with 15-kg HEU casting, while the

Instantons: Dynamical mass generation, chiral ward identities and the topological charge correlation function

Energy Technology Data Exchange (ETDEWEB)

McDougall, N.A. (Oxford Univ. (UK). Dept. of Theoretical Physics)

1983-01-10

When dynamical mass generation resulting from the breakdown of chiral symmetry is taken into account, instanton dynamics treated within the dilute gas approximation may satisfy the constraints on the quark condensates and the topological charge correlation function derived by Crewther from an analysis of the chiral Ward identities assuming the absence of a physical axial U(1) Goldstone boson. From a consideration of the contribution of the eta' to the topological charge correlation function, a relationship is derived in which msub(eta')/sup 2/fsub(eta')/sup 2/ is proportional to the vacuum energy density.

Multi-configurational explicitly correlated wave functions for the study of confined many electron atoms

International Nuclear Information System (INIS)

Sarsa, A; Buendía, E; Gálvez, F J

2016-01-01

Explicitly correlated wave functions to study confined atoms under impenetrable spherical walls have been obtained. Configuration mixing and a correlation factor are included in the variational ansatz. The behaviors of the ground state and some low-lying excited states of He, Be, B and C atoms with the confinement size are analyzed. Level crossing with confinement is found for some cases. This effect is analyzed in terms of the single particle energy of the occupied orbitals. The multi-configuration parameterized optimized effective potential method is employed with a cut-off factor to account for Dirichlet boundary conditions. The variational Monte Carlo method is used to deal with explicitly correlated wave functions. (paper)

46 CFR 185.602 - Hull markings.

Science.gov (United States)

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Hull markings. 185.602 Section 185.602 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) OPERATIONS Markings Required § 185.602 Hull markings. (a) Each vessel must be marked as required by part 67...

Shear wave elastography results correlate with liver fibrosis histology and liver function reserve.

Science.gov (United States)

Feng, Yan-Hong; Hu, Xiang-Dong; Zhai, Lin; Liu, Ji-Bin; Qiu, Lan-Yan; Zu, Yuan; Liang, Si; Gui, Yu; Qian, Lin-Xue

2016-05-07

To evaluate the correlation of shear wave elastography (SWE) results with liver fibrosis histology and quantitative function reserve. Weekly subcutaneous injection of 60% carbon tetrachloride (1.5 mL/kg) was given to 12 canines for 24 wk to induce experimental liver fibrosis, with olive oil given to 2 control canines. At 24 wk, liver condition was evaluated using clinical biochemistry assays, SWE imaging, lidocaine metabolite monoethylglycine-xylidide (MEGX) test, and histologic fibrosis grading. Clinical biochemistry assays were performed at the institutional central laboratory for routine liver function evaluation. Liver stiffness was measured in triplicate from three different intercostal spaces and expressed as mean liver stiffness modulus (LSM). Plasma concentrations of lidocaine and its metabolite MEGX were determined using high-performance liquid chromatography repeated in duplicate. Liver biopsy samples were fixed in 10% formaldehyde, and liver fibrosis was graded using the modified histological activity index Knodell score (F0-F4). Correlations among histologic grading, LSM, and MEGX measures were analyzed with the Pearson linear correlation coefficient. At 24 wk liver fibrosis histologic grading was as follows: F0, n = 2 (control); F1, n = 0; F2, n = 3; F3, n = 7; and F4, n = 2. SWE LSM was positively correlated with histologic grading (r = 0.835, P function reserve in experimental severe fibrosis and cirrhosis.

Quantum electrodynamics and light rays. [Two-point correlation functions

Energy Technology Data Exchange (ETDEWEB)

Sudarshan, E.C.G.

1978-11-01

Light is a quantum electrodynamic entity and hence bundles of rays must be describable in this framework. The duality in the description of elementary optical phenomena is demonstrated in terms of two-point correlation functions and in terms of collections of light rays. The generalizations necessary to deal with two-slit interference and diffraction by a rectangular slit are worked out and the usefulness of the notion of rays of darkness illustrated. 10 references.

The correlation of metrics in complex networks with applications in functional brain networks

International Nuclear Information System (INIS)

Li, C; Wang, H; Van Mieghem, P; De Haan, W; Stam, C J

2011-01-01

An increasing number of network metrics have been applied in network analysis. If metric relations were known better, we could more effectively characterize networks by a small set of metrics to discover the association between network properties/metrics and network functioning. In this paper, we investigate the linear correlation coefficients between widely studied network metrics in three network models (Bárabasi–Albert graphs, Erdös–Rényi random graphs and Watts–Strogatz small-world graphs) as well as in functional brain networks of healthy subjects. The metric correlations, which we have observed and theoretically explained, motivate us to propose a small representative set of metrics by including only one metric from each subset of mutually strongly dependent metrics. The following contributions are considered important. (a) A network with a given degree distribution can indeed be characterized by a small representative set of metrics. (b) Unweighted networks, which are obtained from weighted functional brain networks with a fixed threshold, and Erdös–Rényi random graphs follow a similar degree distribution. Moreover, their metric correlations and the resultant representative metrics are similar as well. This verifies the influence of degree distribution on metric correlations. (c) Most metric correlations can be explained analytically. (d) Interestingly, the most studied metrics so far, the average shortest path length and the clustering coefficient, are strongly correlated and, thus, redundant. Whereas spectral metrics, though only studied recently in the context of complex networks, seem to be essential in network characterizations. This representative set of metrics tends to both sufficiently and effectively characterize networks with a given degree distribution. In the study of a specific network, however, we have to at least consider the representative set so that important network properties will not be neglected

Current Issues in Finite-T Density-Functional Theory and Warm-Correlated Matter †

Directory of Open Access Journals (Sweden)

M. W. C. Dharma-wardana

2016-03-01

Full Text Available Finite-temperature density functional theory (DFT has become of topical interest, partly due to the increasing ability to create novel states of warm-correlated matter (WCM.Warm-dense matter (WDM, ultra-fast matter (UFM, and high-energy density matter (HEDM may all be regarded as subclasses of WCM. Strong electron-electron, ion-ion and electron-ion correlation effects and partial degeneracies are found in these systems where the electron temperature Te is comparable to the electron Fermi energy EF. Thus, many electrons are in continuum states which are partially occupied. The ion subsystem may be solid, liquid or plasma, with many states of ionization with ionic charge Zj. Quasi-equilibria with the ion temperature Ti ≠ Te are common. The ion subsystem in WCM can no longer be treated as a passive “external potential”, as is customary in T = 0 DFT dominated by solid-state theory or quantum chemistry. Many basic questions arise in trying to implement DFT for WCM. Hohenberg-Kohn-Mermin theory can be adapted for treating these systems if suitable finite-T exchange-correlation (XC functionals can be constructed. They are functionals of both the one-body electron density ne and the one-body ion densities ρj. Here, j counts many species of nuclei or charge states. A method of approximately but accurately mapping the quantum electrons to a classical Coulomb gas enables one to treat electron-ion systems entirely classically at any temperature and arbitrary spin polarization, using exchange-correlation effects calculated in situ, directly from the pair-distribution functions. This eliminates the need for any XC-functionals. This classical map has been used to calculate the equation of state of WDM systems, and construct a finite-T XC functional that is found to be in close agreement with recent quantum path-integral simulation data. In this review, current developments and concerns in finite-T DFT, especially in the context of non-relativistic warm

Effects of wave function correlations on scaling violation in quasi-free electron scattering

International Nuclear Information System (INIS)

Tornow, V.; Drechsel, D.; Orlandini, G.; Traini, M.

1981-01-01

The scaling law in quasi-free electron scattering is broken due to the existence of exchange forces, leading to a finite mean value of the scaling variable anti y. This effect is considerably increased by wave function correlations, in particular by tensor correlations, similar to the case of the photonuclear enhancement factor k. (orig.)

The elderly health status and its correlation with ageing biomarkers: the European Project Mark-Age

OpenAIRE

Pini, Elisa

2014-01-01

According to the latest statistics projections formulated by Eurostat, the proportion of elderly EU-27’s population aged over 65 years old is predicted to increase from 17.5 % in 2011 to 29.5 % by 2060. This "population explosion" makes extremely important to identify the different genetic and molecular mechanisms which underpin the morbidity and mortality along with new strategies able to counteract or slow down its progress. In this scenario fits the European Project MARK-AGE who...

Theory for site-site pair distribution functions of molecular fluids. II. Approximations for the Percus--Yevick site-site direct correlation functions

International Nuclear Information System (INIS)

Johnson, E.

1977-01-01

A theory for site-site pair distribution functions of molecular fluids is derived from the Ornstein-Zernike equation. Atom-atom pair distribution functions of this theory which were obtained by using different approximations for the Percus-Yevick site-site direct correlation functions are compared

Mark Kostabi soovib muuta inimesi õnnelikumaks / Kalev Mark Kostabi

Index Scriptorium Estoniae

Kostabi, Kalev Mark, 1960-

2008-01-01

Kalev Mark Kostabi oma sisekujunduslikest eelistustest, ameeriklaste ja itaallaste kodude sisekujunduse erinevustest, kunstist kui ruumikujunduse ühest osast, oma New Yorgi ja Rooma korterite kujundusest

Causal Correlation Functions and Fourier Transforms: Application in Calculating Pressure Induced Shifts

Science.gov (United States)

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

2012-01-01

By adopting a concept from signal processing, instead of starting from the correlation functions which are even, one considers the causal correlation functions whose Fourier transforms become complex. Their real and imaginary parts multiplied by 2 are the Fourier transforms of the original correlations and the subsequent Hilbert transforms, respectively. Thus, by taking this step one can complete the two previously needed transforms. However, to obviate performing the Cauchy principal integrations required in the Hilbert transforms is the greatest advantage. Meanwhile, because the causal correlations are well-bounded within the time domain and band limited in the frequency domain, one can replace their Fourier transforms by the discrete Fourier transforms and the latter can be carried out with the FFT algorithm. This replacement is justified by sampling theory because the Fourier transforms can be derived from the discrete Fourier transforms with the Nyquis rate without any distortions. We apply this method in calculating pressure induced shifts of H2O lines and obtain more reliable values. By comparing the calculated shifts with those in HITRAN 2008 and by screening both of them with the pair identity and the smooth variation rules, one can conclude many of shift values in HITRAN are not correct.

Spectral density analysis of time correlation functions in lattice QCD using the maximum entropy method

International Nuclear Information System (INIS)

Fiebig, H. Rudolf

2002-01-01

We study various aspects of extracting spectral information from time correlation functions of lattice QCD by means of Bayesian inference with an entropic prior, the maximum entropy method (MEM). Correlator functions of a heavy-light meson-meson system serve as a repository for lattice data with diverse statistical quality. Attention is given to spectral mass density functions, inferred from the data, and their dependence on the parameters of the MEM. We propose to employ simulated annealing, or cooling, to solve the Bayesian inference problem, and discuss the practical issues of the approach

[Correlation of medial compartmental joint line elevation with femorotibial angle correction and clinical function after unicompartmental arthroplasty].

Science.gov (United States)

Zhang, Zhan-Feng; Wang, Dan; Min, Ji-Kang

2017-04-25

To study the correlation of postoperative femorotibial angle with medial compartmental joint line elevation after unicompartmental arthroplasty(UKA), as well as the correlation of joint line elevation with the clinical function by measuring radiological joint line. A retrospective study of 56 patients from July 2012 to August 2015 was performed. The mean body mass index (BMI) was 23.5 (ranged, 18.3 to 30.1). The standing anteroposterior radiographs of these patients were assessed both pre-and post-operatively, and the knee function was evaluated according to HSS grading. The correlation between postoperative femorotibial angle(FTA) and joint line elevation was analyzed as well as the correlation between joint line elevation and the clinical function. The mean medial joint line elevation was (2.2±2.0) mm(ranged, -3.3 to 7.0 mm), and the mean FTA correction was (2.3±3.0)°(ranged, -4.5° to 9.6°). The mean follow-up period was 12.2 months. There was a significant correlation between in joint line elevation and FTA correction( P clinical function( P >0.05). There was a significant correlation between medial compartmental joint line elevation and FTA correction after UKA, and the proximal tibial osteotomy was critical during the procedure. There was no significant correlation between joint line elevation and the clinical function, which may be related to the design of UKA prosthesis.

27 CFR 28.193 - Export marks.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Export marks. 28.193... Drawback Filing of Notice and Removal § 28.193 Export marks. In addition to the marks and brands required... chapter, the exporter shall mark the word “Export” on the Government side of each case or Government head...

27 CFR 28.103 - Export marks.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Export marks. 28.103... Manufacturing Bonded Warehouse § 28.103 Export marks. (a) General. In addition to the marks and brands required... provisions of part 19 of this chapter, the proprietor shall mark the word “Export” on the Government side of...

27 CFR 28.144 - Export marks.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Export marks. 28.144... § 28.144 Export marks. (a) General Requirement. In addition to the marks and brands required to be... brewer shall mark the word “Export” on each container or case of beer, or the words “Beer concentrate for...

27 CFR 28.154 - Export marks.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Export marks. 28.154..., for Exportation or Transfer to a Foreign-Trade Zone § 28.154 Export marks. In addition to the marks... provisions of part 19 of this chapter, the proprietor shall mark the word “Export” on the Government side of...

Air trapping on HRCT in asthmatics: correlation with pulmonary function test

International Nuclear Information System (INIS)

Hwang, Jung Hwa; Cha, Chull Hee; Park, Jai Soung; Kim, Young Beom; Lee, Hae Kyung; Choi, Deuk Lin; Kim, Kyung Ho; Park, Choon Sik

1997-01-01

To evaluate on the basis of the pulmonary function test the correlation between the extent of air trapping on HRCT with the severity of airway obstruction and also to identify the prognostic effect of the extent of air trapping after treatment of asthma. Thirty five patients with clinically diagnosed bronchial asthma and air trapping, as seen on HRCT, were included in this study. We quantitatively analysed on HRCT the extent of air trapping and then statistically compared this with the clinical parameters of the pulmonary function test. We classified the patients into two groups on the basis of the pulmonary function test and clinical status : Group 1 (N=35), the total number of asthmatic patients; Group 2 (N=18), relatively stable asthmatics without acute asthmatic attack who showed FEV1 of more than 80% of the predicted value. Using the functional paramenters of PEFR, one of the obijective indicators of improvement in airway obstruction, we also classified the patients into three groups on the basis of interval between treatment and clinical improvement. The result of this was as follows : group 1, asymptomatic group (initial PEFR within normal limit, N=7); group 2, early responder (improvement of PEFR within three hospital days, N=18); group 3, late responder (improvement of PEFR within fourteen hospital days should there be a number here). Using HRCT, we then statistically analysed the differences between the three groups in the extent of air trapping. Among the total of 35 asthmatics, the extent of air trapping on HRCT showed significant correlation with FEV1 (r= -0.6161, p < 0.001) and MEFR (r= -0.6012, p < 0.001). Among the relatively stable asthmatics who showed FEV1 more than 80% of the predicted value, MEFR (r= -0.7553, p < 0.001) and FEF75 (r= -0.7529, p=0.012) showed statistically significant correlation with the extent of air trapping on HRCT, but there was no significant correlation between air trapping on HRCT and FEV1. In the three groups of

Air trapping on HRCT in asthmatics: correlation with pulmonary function test

Energy Technology Data Exchange (ETDEWEB)

Hwang, Jung Hwa; Cha, Chull Hee; Park, Jai Soung; Kim, Young Beom; Lee, Hae Kyung; Choi, Deuk Lin; Kim, Kyung Ho; Park, Choon Sik [Soonchunhyang Univ. College of Medicine, Seoul (Korea, Republic of)

1997-02-01

To evaluate on the basis of the pulmonary function test the correlation between the extent of air trapping on HRCT with the severity of airway obstruction and also to identify the prognostic effect of the extent of air trapping after treatment of asthma. Thirty five patients with clinically diagnosed bronchial asthma and air trapping, as seen on HRCT, were included in this study. We quantitatively analysed on HRCT the extent of air trapping and then statistically compared this with the clinical parameters of the pulmonary function test. We classified the patients into two groups on the basis of the pulmonary function test and clinical status : Group 1 (N=35), the total number of asthmatic patients; Group 2 (N=18), relatively stable asthmatics without acute asthmatic attack who showed FEV1 of more than 80% of the predicted value. Using the functional paramenters of PEFR, one of the obijective indicators of improvement in airway obstruction, we also classified the patients into three groups on the basis of interval between treatment and clinical improvement. The result of this was as follows : group 1, asymptomatic group (initial PEFR within normal limit, N=7); group 2, early responder (improvement of PEFR within three hospital days, N=18); group 3, late responder (improvement of PEFR within fourteen hospital days should there be a number here). Using HRCT, we then statistically analysed the differences between the three groups in the extent of air trapping. Among the total of 35 asthmatics, the extent of air trapping on HRCT showed significant correlation with FEV1 (r= -0.6161, p < 0.001) and MEFR (r= -0.6012, p < 0.001). Among the relatively stable asthmatics who showed FEV1 more than 80% of the predicted value, MEFR (r= -0.7553, p < 0.001) and FEF75 (r= -0.7529, p=0.012) showed statistically significant correlation with the extent of air trapping on HRCT, but there was no significant correlation between air trapping on HRCT and FEV1. In the three groups of

1L Mark-IV Target Design Review

Energy Technology Data Exchange (ETDEWEB)

Koehler, Paul E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-11-16

This presentation includes General Design Considerations; Current (Mark-III) Lower Tier; Mark-III Upper Tier; Performance Metrics; General Improvements for Material Science; General Improvements for Nuclear Science; Improving FOM for Nuclear Science; General Design Considerations Summary; Design Optimization Studies; Expected Mark-IV Performance: Material Science; Expected Mark-IV Performance: Nuclear Science (Disk); Mark IV Enables Much Wider Range of Nuclear-Science FOM Gains than Mark III; Mark-IV Performance Summary; Rod or Disk? Center or Real FOV?; and Project Cost and Schedule.

Structure function analysis of long-range correlations in plasma turbulence

International Nuclear Information System (INIS)

Yu, C.X.; Gilmore, M.; Peebles, W.A.; Rhodes, T.L.

2003-01-01

Long-range correlations (temporal and spatial) have been predicted in a number of different turbulence models, both analytical and numerical. These long-range correlations are thought to significantly affect cross-field turbulent transport in magnetically confined plasmas. The Hurst exponent, H - one of a number of methods to identify the existence of long-range correlations in experimental data - can be used to quantify self-similarity scalings and correlations in the mesoscale temporal range. The Hurst exponent can be calculated by several different algorithms, each of which has particular advantages and disadvantages. One method for calculating H is via structure functions (SFs). The SF method is a robust technique for determining H with several inherent advantages that has not yet been widely used in plasma turbulence research. In this article, the SF method and its advantages are discussed in detail, using both simulated and measured fluctuation data from the DIII-D tokamak [J. L. Luxon and L. G. Davis, Fusion Technol. 8, 441 (1985)]. In addition, it is shown that SFs used in conjunction with rescaled range analysis (another method for calculating H) can be used to mitigate the effects of coherent modes in some cases

Correlation functions of electronic and nuclear spins in a Heisenberg antiferromagnet semi-infinite medium

International Nuclear Information System (INIS)

Sarmento, E.F.

1981-01-01

Results are found for the dynamical correlation functions (or its corresponding Green's functions) among any combination including operator pairs of electronic and nuclear spins in an antiferromagnet semi-infinite medium, at low temperatures T [pt

A note on a perfect simulation algorithm for marked Hawkes processes

DEFF Research Database (Denmark)

Møller, Jesper; Rasmussen, Jakob Gulddahl

2004-01-01

The usual straightforward simulation algorithm for (marked or unmarked) Hawkes processes suffers from edge effect. In this note we describe a perfect simulation algorithm which is partly derived as in Brix and Kendall (2002) and partly using upper and lower processes as in the Propp......-Wilson algorithm (1996), or rather as in the dominated CFTP algorithm by Kendall and Moller (2000). Various monotonicity properties and approximations of the cumulative distribution function for the length of a so-called cluster in a marked Hawkes process play an important role....

General solution of an exact correlation function factorization in conformal field theory

International Nuclear Information System (INIS)

Simmons, Jacob J H; Kleban, Peter

2009-01-01

The correlation function factorization with K a boundary operator product expansion coefficient, is known to hold for certain scaling operators at the two-dimensional percolation point and in a few other cases. Here the correlation functions are evaluated in the upper half-plane (or any conformally equivalent region) with x 1 and x 2 arbitrary points on the real axis, and z an arbitrary point in the interior. This type of result is of interest because it is both exact and universal, relates higher-order correlation functions to lower-order ones and has a simple interpretation in terms of cluster or loop probabilities in several statistical models. This motivated us to use the techniques of conformal field theory to determine the general conditions for its validity. Here, we discover that either (see display) factorizes in this way for any central charge c, generalizing previous results. In particular, the factorization holds for either FK (Fortuin–Kasteleyn) or spin clusters in the Q-state Potts models; it also applies to either the dense or dilute phases of the O(n) loop models. Further, only one other non-trivial set of highest-weight operators (in an irreducible Verma module) factorizes in this way. In this case the operators have negative dimension (for c<1) and do not seem to have a physical realization

Time-dependent friction and solvation time correlation function

International Nuclear Information System (INIS)

Samanta, Alok; Ali, Sk Musharaf; Ghosh, Swapan K

2005-01-01

We have derived a new relation between the time-dependent friction and solvation time correlation function (STCF) for non-polar fluids. The friction values calculated using this relation and simulation results on STCF for a Lennard-Jones fluid are shown to have excellent agreement with the same obtained through mode-coupling theory. Also derived is a relation between the time-dependent dielectric friction and STCF for polar fluids. Routes are thus provided to obtain the time-dependent friction (non-polar as well as dielectric) from an experimentally measured quantity like STCF, even if the interparticle interaction potential is not known

Correlation functions of one-dimensional bosons at low temperature

Energy Technology Data Exchange (ETDEWEB)

Kozlowski, K.K. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Maillet, J.M. [CNRS, ENS Lyon (France). Lab. de Physique; Slavnov, N.A. [Steklov Mathematical Institute, Moscow (Russian Federation)

2010-12-15

We consider the low-temperature limit of the long-distance asymptotic behavior of the finite temperature density-density correlation function in the one-dimensional Bose gas derived recently in the algebraic Bethe Ansatz framework. Our results confirm the predictions based on the Luttinger liquid and conformal field theory approaches. We also demonstrate that the amplitudes arising in this asymptotic expansion at low-temperature coincide with the amplitudes associated with the so-called critical form factors. (orig.)

On Soft Limits of Large-Scale Structure Correlation Functions

OpenAIRE

Ben-Dayan, Ido; Konstandin, Thomas; Porto, Rafael A.; Sagunski, Laura

2014-01-01

We study soft limits of correlation functions for the density and velocity fields in the theory of structure formation. First, we re-derive the (resummed) consistency conditions at unequal times using the eikonal approximation. These are solely based on symmetry arguments and are therefore universal. Then, we explore the existence of equal-time relations in the soft limit which, on the other hand, depend on the interplay between soft and hard modes. We scrutinize two approaches in the literat...

Fast Computation of the Two-Point Correlation Function in the Age of Big Data

Science.gov (United States)

Pellegrino, Andrew; Timlin, John

2018-01-01

We present a new code which quickly computes the two-point correlation function for large sets of astronomical data. This code combines the ease of use of Python with the speed of parallel shared libraries written in C. We include the capability to compute the auto- and cross-correlation statistics, and allow the user to calculate the three-dimensional and angular correlation functions. Additionally, the code automatically divides the user-provided sky masks into contiguous subsamples of similar size, using the HEALPix pixelization scheme, for the purpose of resampling. Errors are computed using jackknife and bootstrap resampling in a way that adds negligible extra runtime, even with many subsamples. We demonstrate comparable speed with other clustering codes, and code accuracy compared to known and analytic results.

Reliability measures in item response theory: manifest versus latent correlation functions.

Science.gov (United States)

Milanzi, Elasma; Molenberghs, Geert; Alonso, Ariel; Verbeke, Geert; De Boeck, Paul

2015-02-01

For item response theory (IRT) models, which belong to the class of generalized linear or non-linear mixed models, reliability at the scale of observed scores (i.e., manifest correlation) is more difficult to calculate than latent correlation based reliability, but usually of greater scientific interest. This is not least because it cannot be calculated explicitly when the logit link is used in conjunction with normal random effects. As such, approximations such as Fisher's information coefficient, Cronbach's α, or the latent correlation are calculated, allegedly because it is easy to do so. Cronbach's α has well-known and serious drawbacks, Fisher's information is not meaningful under certain circumstances, and there is an important but often overlooked difference between latent and manifest correlations. Here, manifest correlation refers to correlation between observed scores, while latent correlation refers to correlation between scores at the latent (e.g., logit or probit) scale. Thus, using one in place of the other can lead to erroneous conclusions. Taylor series based reliability measures, which are based on manifest correlation functions, are derived and a careful comparison of reliability measures based on latent correlations, Fisher's information, and exact reliability is carried out. The latent correlations are virtually always considerably higher than their manifest counterparts, Fisher's information measure shows no coherent behaviour (it is even negative in some cases), while the newly introduced Taylor series based approximations reflect the exact reliability very closely. Comparisons among the various types of correlations, for various IRT models, are made using algebraic expressions, Monte Carlo simulations, and data analysis. Given the light computational burden and the performance of Taylor series based reliability measures, their use is recommended. © 2014 The British Psychological Society.

Time-dependent importance sampling in semiclassical initial value representation calculations for time correlation functions.

Science.gov (United States)

Tao, Guohua; Miller, William H

2011-07-14

An efficient time-dependent importance sampling method is developed for the Monte Carlo calculation of time correlation functions via the initial value representation (IVR) of semiclassical (SC) theory. A prefactor-free time-dependent sampling function weights the importance of a trajectory based on the magnitude of its contribution to the time correlation function, and global trial moves are used to facilitate the efficient sampling the phase space of initial conditions. The method can be generally applied to sampling rare events efficiently while avoiding being trapped in a local region of the phase space. Results presented in the paper for two system-bath models demonstrate the efficiency of this new importance sampling method for full SC-IVR calculations.

Structure of N = 2 superconformally invariant unitary ''minimal'' theories: Operator algebra and correlation functions

International Nuclear Information System (INIS)

Kiritsis, E.B.

1987-01-01

N = 2 superconformal-invariant theories are studied and their general structure is analyzed. The geometry of N = 2 complex superspace is developed as a tool to study the correlation functions of the theories above. The Ward identities of the global N = 2 superconformal symmetry are solved, to restrict the form of correlation functions. Advantage is taken of the existence of the degenerate operators to derive the ''fusion'' rules for the unitary minimal systems with c<1. In particular, the closure of the operator algebra for such systems is shown. The c = (1/3 minimal system is analyzed and its two-, three-, and four-point functions as well as its operator algebra are calculated explicitly

Brain perfusion correlates of cognitive and nigrostriatal functions in de novo Parkinson's disease

International Nuclear Information System (INIS)

Nobili, Flavio; Arnaldi, Dario; Campus, Claudio; Ferrara, Michela; Brugnolo, Andrea; Dessi, Barbara; Girtler, Nicola; Rodriguez, Guido; De Carli, Fabrizio; Morbelli, Silvia; Sambuceti, Gianmario; Abruzzese, Giovanni

2011-01-01

Subtle cognitive impairment is recognized in the first stages of Parkinson's disease (PD), including executive, memory and visuospatial dysfunction, but its pathophysiological basis is still debated. Twenty-six consecutive, drug-naive, de novo PD patients underwent an extended neuropsychological battery, dopamine transporter (DAT) and brain perfusion single photon emission computed tomography (SPECT). We previously reported that nigrocaudate impairment correlates with executive functions, and nigroputaminal impairment with visuospatial abilities. Here perfusion SPECT was first compared between the PD group and age-matched controls (CTR). Then, perfusion SPECT was correlated with both DAT SPECT and four neuropsychological factors by means of voxel-based analysis (SPM8) with a height threshold of p < 0.005 at peak level and p < 0.05 false discovery rate-corrected at cluster level. Both perfusion and DAT SPECT images were flipped in order to have the more affected hemisphere (MAH), defined clinically, on the same side. Significant hypoperfusion was found in an occipital area of the MAH in PD patients as compared to CTR. Executive functions directly correlated with brain perfusion in bilateral posterior cingulate cortex and precuneus in the less affected hemisphere (LAH), while verbal memory directly correlated with perfusion in the precuneus, inferior parietal lobule and superior temporal gyrus in the LAH. Furthermore, positive correlation was highlighted between nigrocaudate and nigroputaminal impairment and brain perfusion in the precuneus, posterior cingulate and parahippocampal gyri of the LAH. These data support the evidence showing an early involvement of the cholinergic system in the early cognitive dysfunction and point to a more relevant role of parietal lobes and posterior cingulate in executive functions in PD. (orig.)

Skeletal muscle magnetic resonance biomarkers correlate with function and sentinel events in Duchenne muscular dystrophy.

Science.gov (United States)

Barnard, Alison M; Willcocks, Rebecca J; Finanger, Erika L; Daniels, Michael J; Triplett, William T; Rooney, William D; Lott, Donovan J; Forbes, Sean C; Wang, Dah-Jyuu; Senesac, Claudia R; Harrington, Ann T; Finkel, Richard S; Russman, Barry S; Byrne, Barry J; Tennekoon, Gihan I; Walter, Glenn A; Sweeney, H Lee; Vandenborne, Krista

2018-01-01

To provide evidence for quantitative magnetic resonance (qMR) biomarkers in Duchenne muscular dystrophy by investigating the relationship between qMR measures of lower extremity muscle pathology and functional endpoints in a large ambulatory cohort using a multicenter study design. MR spectroscopy and quantitative imaging were implemented to measure intramuscular fat fraction and the transverse magnetization relaxation time constant (T2) in lower extremity muscles of 136 participants with Duchenne muscular dystrophy. Measures were collected at 554 visits over 48 months at one of three imaging sites. Fat fraction was measured in the soleus and vastus lateralis using MR spectroscopy, while T2 was assessed using MRI in eight lower extremity muscles. Ambulatory function was measured using the 10m walk/run, climb four stairs, supine to stand, and six minute walk tests. Significant correlations were found between all qMR and functional measures. Vastus lateralis qMR measures correlated most strongly to functional endpoints (|ρ| = 0.68-0.78), although measures in other rapidly progressing muscles including the biceps femoris (|ρ| = 0.63-0.73) and peroneals (|ρ| = 0.59-0.72) also showed strong correlations. Quantitative MR biomarkers were excellent indicators of loss of functional ability and correlated with qualitative measures of function. A VL FF of 0.40 was an approximate lower threshold of muscle pathology associated with loss of ambulation. Lower extremity qMR biomarkers have a robust relationship to clinically meaningful measures of ambulatory function in Duchenne muscular dystrophy. These results provide strong supporting evidence for qMR biomarkers and set the stage for their potential use as surrogate outcomes in clinical trials.

High contrast laser marking of alumina

International Nuclear Information System (INIS)

Penide, J.; Quintero, F.; Riveiro, A.; Fernández, A.; Val, J. del; Comesaña, R.; Lusquiños, F.; Pou, J.

2015-01-01

Highlights: • Laser marking of alumina using near infrared (NIR) lasers was experimentally analyzed. • Color change produced by NIR lasers is due to thermally induced oxygen vacancies. • Laser marking results obtained using NIR lasers and green laser are compared. • High contrast marks on alumina were achieved. - Abstract: Alumina serves as raw material for a broad range of advanced ceramic products. These elements should usually be identified by some characters or symbols printed directly on them. In this sense, laser marking is an efficient, reliable and widely implemented process in industry. However, laser marking of alumina still leads to poor results since the process is not able to produce a dark mark, yielding bad contrast. In this paper, we present an experimental study on the process of marking alumina by three different lasers working in two wavelengths: 1064 nm (Near-infrared) and 532 nm (visible, green radiation). A colorimetric analysis has been carried out in order to compare the resulting marks and its contrast. The most suitable laser operating conditions were also defined and are reported here. Moreover, the physical process of marking by NIR lasers is discussed in detail. Field Emission Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy were also employed to analyze the results. Finally, we propose an explanation for the differences of the coloration induced under different atmospheres and laser parameters. We concluded that the atmosphere is the key parameter, being the inert one the best choice to produce the darkest marks

Use of W-boson longitudinal-transverse interference in top quark spin-correlation functions