Measuring baryon acoustic oscillations with angular two-point correlation function
Alcaniz, Jailson S; Bernui, Armando; Carvalho, Joel C; Benetti, Micol
2016-01-01
The Baryon Acoustic Oscillations (BAO) imprinted a characteristic correlation length in the large-scale structure of the universe that can be used as a standard ruler for mapping out the cosmic expansion history. Here, we discuss the application of the angular two-point correlation function, $w(\\theta)$, to a sample of luminous red galaxies of the Sloan Digital Sky Survey (SDSS) and derive two new measurements of the BAO angular scale at $z = 0.235$ and $z = 0.365$. Since noise and systematics may hinder the identification of the BAO signature in the $w - \\theta$ plane, we also introduce a potential new method to localize the acoustic bump in a model-independent way. We use these new measurements along with previous data to constrain cosmological parameters of dark energy models and to derive a new estimate of the acoustic scale $r_s$.
Accuracy of two points correlation length measurement and its applications in H-1NF heliac
Kim, Jaewook; Michael, C. A.; Nam, Y. U.; Lampert, M.; Ghim, Y. C.
2016-10-01
Anomalous transport observed in fusion-grade plasmas is widely accepted to be correlated with spatial and temporal correlation characteristics of the turbulent eddies. While temporal and 2D spatial (radial and poloidal) correlation characteristics have been studied in detail, the lack of such information in the parallel direction, with respect to the background magnetic field, of hot core plasmas precludes us from full understanding and controlling plasma turbulence. KSTAR is equipped with a couple of 2D diagnostic systems measuring ion-scale density fluctuations, namely the BES and MIR systems, at two different toroidal locations. These systems provide a possibility to measure a parallel correlation length. As it is necessary to identify how reliably one can measure correlation length with only two spatial positions, there has been such a study [Jaewook Kim et al., Nucl. Fusion accepted] recently. Based on this recent study, we experimentally obtained 3D correlation functions from H-1NF heliac using the data from a set of Langmuir probes. One probe is spatially fixed, while the second one is scanned radially and poloidally at a different toroidal location. H1-NF heliac plasmas are highly reproducible, therefore we construct the 3D correlation functions with multi-discharges.
Contreras, Carlos; Poole, Gregory B; Marin, Felipe; Brough, Sarah; Colless, Matthew; Couch, Warrick; Croom, Scott; Croton, Darren; Davis, Tamara M; Drinkwater, Michael J; Forster, Karl; Gilbank, David; Gladders, Mike; Glazebrook, Karl; Jelliffe, Ben; Jurek, Russell J; Li, I-hui; Madore, Barry; Martin, D Christopher; Pimbblet, Kevin; Pracy, Michael; Sharp, Rob; Wisnioski, Emily; Woods, David; Wyder, Ted K; Yee, H K C; 10.1093/mnras/sts608
2013-01-01
The growth history of large-scale structure in the Universe is a powerful probe of the cosmological model, including the nature of dark energy. We study the growth rate of cosmic structure to redshift $z = 0.9$ using more than $162{,}000$ galaxy redshifts from the WiggleZ Dark Energy Survey. We divide the data into four redshift slices with effective redshifts $z = [0.2,0.4,0.6,0.76]$ and in each of the samples measure and model the 2-point galaxy correlation function in parallel and transverse directions to the line-of-sight. After simultaneously fitting for the galaxy bias factor we recover values for the cosmic growth rate which are consistent with our assumed $\\Lambda$CDM input cosmological model, with an accuracy of around 20% in each redshift slice. We investigate the sensitivity of our results to the details of the assumed model and the range of physical scales fitted, making close comparison with a set of N-body simulations for calibration. Our measurements are consistent with an independent power-spe...
Kim, Jaewook; Lampert, M; Ghim, Y -c
2016-01-01
A statistical method for the estimation of spatial correlation lengths of Gaussian-shaped fluctuating signals with two measurement points is examined to quantitatively evaluate its reliability (variance) and accuracy (bias error). The standard deviation of the correlation value is analytically derived for randomly distributed Gaussian shaped fluctuations satisfying stationarity and homogeneity, allowing us to evaluate, as a function of fluctuation-to-noise ratios, sizes of averaging time windows and ratios of the distance between the two measurement points to the true correlation length, the goodness of the two-point measurement for estimating the spatial correlation length. Analytic results are confirmed with numerically generated synthetic data and real experimental data obtained with the KSTAR beam emission spectroscopy diagnostic. Our results can be applied to Gaussian-shaped fluctuating signals where a correlation length must be measured with only two measurement points.
Kim, Jaewook; Nam, Y. U.; Lampert, M.; Ghim, Y.-C.
2016-10-01
A statistical method for the estimation of the spatial correlation lengths of Gaussian-shaped fluctuating signals with two measurement points is examined to quantitatively evaluate its reliability (variance) and accuracy (bias error). The standard deviation of the correlation value is analytically derived for randomly distributed Gaussian shaped fluctuations satisfying stationarity and homogeneity, allowing us to evaluate, as a function of fluctuation-to-noise ratios, the sizes of averaging time windows and the ratios of the distance between the two measurement points to the true correlation length, and the goodness of the two-point measurement for estimating the spatial correlation length. Analytic results are confirmed with numerically generated synthetic data and real experimental data obtained with the KSTAR beam emission spectroscopy diagnostic. Our results can be applied to Gaussian-shaped fluctuating signals where a correlation length must be measured with only two measurement points.
Two-point correlation functions in inhomogeneous and anisotropic cosmologies
Marcori, Oton H.; Pereira, Thiago S.
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.
Two-point Correlator Fits on HISQ Ensembles
Bazavov, A; Bouchard, C; DeTar, C; Du, D; El-Khadra, A X; Foley, J; Freeland, E D; Gamiz, E; Gottlieb, Steven; Heller, U M; Hetrick, J E; Kim, J; Kronfeld, A S; Laiho, J; Levkova, L; Lightman, M; Mackenzie, P B; Neil, E T; Oktay, M; Simone, J N; Sugar, R L; Toussaint, D; Van de Water, R S; Zhou, R
2012-01-01
We present our methods to fit the two point correlators for light, strange, and charmed pseudoscalar meson physics with the highly improved staggered quark (HISQ) action. We make use of the least-squares fit including the full covariance matrix of the correlators and including Gaussian constraints on some parameters. We fit the correlators on a variety of the HISQ ensembles. The lattice spacing ranges from 0.15 fm down to 0.06 fm. The light sea quark mass ranges from 0.2 times the strange quark mass down to the physical light quark mass. The HISQ ensembles also include lattices with different volumes and with unphysical values of the strange quark mass. We use the results from this work to obtain our preliminary results of $f_D$, $f_{D_s}$, $f_{D_s}/f_{D}$, and ratios of quark masses presented in another talk [1].
Flow speed measurement using two-point collective light scattering
Energy Technology Data Exchange (ETDEWEB)
Heinemeier, N.P
1998-09-01
Measurements of turbulence in plasmas and fluids using the technique of collective light scattering have always been plagued by very poor spatial resolution. In 1994, a novel two-point collective light scattering system for the measurement of transport in a fusion plasma was proposed. This diagnostic method was design for a great improvement of the spatial resolution, without sacrificing accuracy in the velocity measurement. The system was installed at the W7-AS steallartor in Garching, Germany, in 1996, and has been operating since. This master thesis is an investigation of the possible application of this new method to the measurement of flow speeds in normal fluids, in particular air, although the results presented in this work have significance for the plasma measurements as well. The main goal of the project was the experimental verification of previous theoretical predictions. However, the theoretical considerations presented in the thesis show that the method can only be hoped to work for flows that are almost laminar and shearless, which makes it of very small practical interest. Furthermore, this result also implies that the diagnostic at W7-AS cannot be expected to give the results originally hoped for. (au) 1 tab., 51 ills., 29 refs.
Logarithmic two-Point Correlation Functions from a z = 2 Lifshitz Model
Zingg, T.
2013-01-01
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 sens
Gauge-fixing parameter dependence of two-point gauge variant correlation functions
Zhai, C
1996-01-01
The gauge-fixing parameter \\xi 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 Computationally Efficient Approach for Calculating Galaxy Two-Point Correlations
Demina, Regina; BenZvi, Segev; Hindrichs, Otto
2016-01-01
We develop a modification to the calculation of the two-point correlation function commonly used in the analysis of large scale structure in cosmology. An estimator of the two-point correlation function is constructed by contrasting the observed distribution of galaxies with that of a uniformly populated random catalog. Using the assumption that the distribution of random galaxies in redshift is independent of angular position allows us to replace pairwise combinatorics with fast integration over probability maps. The new method significantly reduces the computation time while simultaneously increasing the precision of the calculation.
The Two-Point Correlation Function of Gamma-ray Bursts
Li, Ming-Hua
2015-01-01
In this paper, we examine the spacial distribution of gamma-ray bursts (GRBs) using a sample of 373 objects. We subdivide the GRB data into two redshift intervals over the redshift range $0
Characterization of mantle convection experiments using two-point correlation functions
Puster, Peter; Jordan, Thomas H.; Hager, Bradford H.
1995-04-01
Snapshots of the temperature T(r, phi, t), horizontal flow velocity u(r, phi, t), and radial flow velocity w(r, phi, t) obtained from numerical convection experiments of time-dependent flows in annular cylindrical geometry are taken to be samples of stationary, rotationally invariant random fields. For such a field f(r, phi, t), the spatio-temporal two-point correlation function, C(sub ff)(r, r-prime, delta, t(sub *)), is constructed by averaging over rotational transformations of this ensemble. To assess the structural differences among mantle convection experiments we construct three spartial subfunctions of C(sub ff)(r, r-prime, delta, t(sub *)): the rms variation, sigma(sub f)(r), the radial correlation function, R(sub f)(r, r-prime), and the angular correlation function, A(sub f)(r, delta). R(sub f)(r, r-prime) and A(sub f)(r, r-prime) are symmetric about the loci r = r-prime and delta = 0, respectively, where they achieve their maximum value of unity. The falloff of R(sub f) and A(sub f) away from their symmetry can be quantified by a correlation length rho(sub f)(r) and a correlation angle alpha(sub f)(r), which we define to be the half widths of the central peaks at the correlation level 0.75. The behavior of rho(sub f) is a diagnostic of radial structure, while alpha(sub f) measures average plume width. We have used two-point correlation functions of the temperature field (T-diagnostics) and flow velocity fields (V-diagnostics) to quantify some important aspects of mantle convection experiments. We explore the dependence of different correlation diagnostics on Rayleigh number, internal heating rate, and depth- and temperature-dependent viscosity. For isoviscous flows in an annulus, we show how radial averages of sigma(sub T), rho(sub T), and alpha(sub T) scale with Rayleigh number for various internal heating rates. A break in the power-law relationship at the transition from steady to time-dependent regimes is evident for rho(sub T) and alpha(sub T) but
The real space clustering of galaxies in SDSS DR7: I. Two point correlation functions
Shi, Feng; Wang, Huiyuan; Zhang, Youcai; Mo, H J; Bosch, Frank C van den; Li, Shijie; Liu, Chengze; Lu, Yi; Tweed, Dylan; Yang, Lei
2016-01-01
Using a method to correct redshift space distortion (RSD) for individual galaxies, we present the measurements of real space two-point correlation functions (2PCFs) of galaxies in the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7). Galaxy groups selected from the SDSS are used as proxies of dark matter halos to correct the virial motions of galaxies in dark matter halos, and to reconstruct the large-scale velocity field. We use an ensemble of mock catalogs to demonstrate the reliability of our method. Over the range $0.2 < r < 20 h^{-1}{\\rm {Mpc}}$, the 2PCF measured directly in reconstructed real space is better than the measurement error due to cosmic variance, if the reconstruction uses the correct cosmology. Applying the method to the SDSS DR7, we construct a real space version of the main galaxy catalog, which contains 396,068 galaxies in the North Galactic Cap with redshifts in the range $0.01 \\leq z \\leq 0.12$. The Sloan Great Wall, the largest known structure in the nearby Universe, is not...
Futures market efficiency diagnostics via temporal two-point correlations. Russian market case study
Mikhail Kopytin; Evgeniy Kazantsev
2013-01-01
Using a two-point correlation technique, we study emergence of market efficiency in the emergent Russian futures market by focusing on lagged correlations. The correlation strength of leader-follower effects in the lagged inter-market correlations on the hourly time frame is seen to be significant initially (2009-2011) but gradually goes down, as the erstwhile leader instruments -- crude oil, the USD/RUB exchange rate, and the Russian stock market index -- seem to lose the leader status. An i...
Meta-conformal invariance and the boundedness of two-point correlation functions
Henkel, Malte; Stoimenov, Stoimen
2016-11-01
The covariant two-point functions, derived from Ward identities in direct space, can be affected by consistency problems and can become unbounded for large time- or space-separations. This difficulty arises for several extensions of dynamical scaling, for example Schrödinger-invariance, conformal Galilei invariance or meta-conformal invariance, but not for standard ortho-conformal invariance. For meta-conformal invariance in (1+1) dimensions, which acts as a dynamical symmetry of a simple advection equation, these difficulties can be cured by going over to a dual space and an extension of these dynamical symmetries through the construction of a new generator in the Cartan sub-algebra. This provides a canonical interpretation of meta-conformally covariant two-point functions as correlators. Galilei-conformal correlators can be obtained from meta-conformal invariance through a simple contraction. In contrast, by an analogus construction, Schrödinger-covariant two-point functions are causal response functions. All these two-point functions are bounded at large separations, for sufficiently positive values of the scaling exponents.
Meta-conformal invariance and the boundedness of two-point correlation functions
Henkel, Malte
2016-01-01
The covariant two-point functions, derived from Ward identities in direct space, can be affected by consistency problems and can become unbounded for large time- or space-separations. This difficulty arises for several extensions of dynamical scaling, for example Schr\\"odinger-invariance, conformal Galilei invariance or meta-conformal invariance, but not for standard ortho-conformal invariance. For meta-conformal invariance in 1+1 dimensions, these difficulties can be cured by going over to a dual space and an extension of these dynamical symmetries through the construction of a new generator in the Cartan sub-algebra. This provides a canonical interpretation of meta-conformally covariant two-point functions as correlators. Galilei-conformal correlators can be obtained from meta-conformal invariance through a simple contraction. In contrast, by an analogus construction, Schr\\"odinger-covariant two-point functions are causal response functions. All these two-point functions are bounded at large separations, fo...
Equal-time two-point correlation functions in Coulomb gauge Yang-Mills theory
Campagnari, D; Reinhardt, H; Astorga, F; Schleifenbaum, W
2009-01-01
We apply a new functional perturbative approach to the calculation of the equal-time two-point correlation functions and the potential between static color charges to one-loop order in Coulomb gauge Yang-Mills theory. The functional approach proceeds through a solution of the Schroedinger equation for the vacuum wave functional to order g^2 and derives the equal-time correlation functions from a functional integral representation via new diagrammatic rules. We show that the results coincide with those obtained from the usual Lagrangian functional integral approach, extract the beta function and determine the anomalous dimensions of the equal-time gluon and ghost two-point functions and the static potential under the assumption of multiplicative renormalizability to all orders.
Usui, Kouta
2012-01-01
It will be proved that a model of lattice field theories which satisfies (A1) Hermiticity, (A2) translational invariance, (A3) reflection positivity, and (A4) polynomial boundedness of correlations, permits the Kallen-Lehmann representation of two point correlation functions with positive spectral density function. Then, we will also argue that positivity of spectral density functions is necessary for a lattice theory to satisfy conditions (A1) - (A4). As an example, a lattice overlap scalar boson model will be discussed. We will find that the overlap scalar boson violates the reflection positivity.
Banerjee, Supratik; Galtier, Sébastien
2013-01-01
Compressible isothermal magnetohydrodynamic turbulence is analyzed under the assumption of statistical homogeneity and in the asymptotic limit of large kinetic and magnetic Reynolds numbers. Following Kolmogorov we derive an exact relation for some two-point correlation functions which generalizes the expression recently found for hydrodynamics. We show that the magnetic field brings new source and flux terms into the dynamics which may act on the inertial range similarly as a source or a sink for the mean energy transfer rate. The introduction of a uniform magnetic field simplifies significantly the exact relation for which a simple phenomenology may be given. A prediction for axisymmetric energy spectra is eventually proposed.
Two-point correlators revisited: Fast and slow scales in multifield models of Inflation
Ghersi, José T Gálvez
2016-01-01
We study the structure of two-point correlators of the inflationary field fluctuations in order to improve the accuracy and efficiency of the existing spectral methods. We present a description motivated by the separation of the fast and slow evolving components of the spectrum. Our purpose is to rephrase all the relevant equations of motion in terms of slowly varying quantities. This is important in order to consider the contribution from high-frequency modes to the spectrum without affecting computational performance. The slow-roll approximation is not required to reproduce the main distinctive features in the power spectrum for each specific model of inflation.
Logarithmic two-point correlation functions from a z=2 Lifshitz model
Energy Technology Data Exchange (ETDEWEB)
Zingg, T. [Institute for Theoretical Physics and Spinoza Institute, Universiteit Utrecht,Leuvenlaan 4, 3584 CE Utrecht (Netherlands)
2014-01-21
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.
Experimental Study of the Convergence of Two-Point Cross-Correlation Toward the Green's Function
Gouedard, P.; Roux, P.; Campillo, M.; Verdel, A.; Campman, X.
2007-12-01
It has been shown theoretically by several authors that cross-correlation of the seismic motion recorded at two points could yield the Green's Function (GF) between these points. Convergence of cross-correlations toward the GF depends on sources positions and/or the nature of the wavefield. Direct waves from an even distribution of sources can be used to retrieve the GF. On the other hand, in an inhomogeneous medium, recording the diffuse field (coda) is theoretically sufficient to retrieve the GF whatever the sources distribution is. Since none of these two conditions (even distribution of sources or a perfectly diffuse field) is satisfied in practice, the question of convergence toward the GF has to be investigated with real data. A 3D exploration survey with sources and receivers on a dense grid offers such an opportunity. We used a high- resolution survey recorded by Petroleum Development Oman in North Oman. The data have been obtained in a 1x1~km area covered with 1600 geophones located on a 25x25~m-cell grid. Records are 4-seconds long. A unique feature of this survey is that vibrators (working in the [8-120~Hz] frequency band), were located on a similar grid shifted with respect to the receiver grid by half a cell (12.5~m) in both directions. This allows us to compare estimated GF's with measured direct waves (GF's) between the geophones. The shallow subsurface is highly heterogeneous and records include seismic coda. From this dataset, we selected two receiver locations (Ra and Rb) distant from d=158~m. We used both different sets of source locations and time windows to compute the cross-correlation between these two receivers. Then we compared the derivatives of correlation functions with the actual GF measured in Rb (resp.~Ra) for a source close to Ra (resp.~Rb). By doing so, we show the actual influence of source locations and scattering (governed by the records' selected time window) on the Signal-to-Noise Ratio (SNR) of the reconstructed GF. When using
Directory of Open Access Journals (Sweden)
Volodymyr V. Kindratenko
2009-01-01
Full Text Available We present a parallel implementation of an algorithm for calculating the two-point angular correlation function as applied in the field of computational cosmology. The algorithm has been specifically developed for a reconfigurable computer. Our implementation utilizes a microprocessor and two reconfigurable processors on a dual-MAP SRC-6 system. The two reconfigurable processors are used as two application-specific co-processors. Two independent computational kernels are simultaneously executed on the reconfigurable processors while data pre-fetching from disk and initial data pre-processing are executed on the microprocessor. The overall end-to-end algorithm execution speedup achieved by this implementation is over 90× as compared to a sequential implementation of the algorithm executed on a single 2.8 GHz Intel Xeon microprocessor.
Analysis of errors in the measurement of energy dissipation with two-point LDA
Energy Technology Data Exchange (ETDEWEB)
Ducci, A.; Yianneskis, M. [Department of Mechanical Engineering, King' s College London, Experimental and Computational Laboratory for the Analysis of Turbulence (ECLAT), London (United Kingdom)
2005-04-01
In the present study, an attempt has been made to identify and quantify, with a rigorous analytical approach, all possible sources of error involved in the estimation of the fluctuating velocity gradients ({partial_derivative}u{sub i}/{partial_derivative}x{sub j}){sup 2} when a two-point laser Doppler velocimetry (LDV) technique is employed. Measurements were carried out in a grid-generated turbulence flow where the local dissipation rate can be calculated from the decay of kinetic energy. An assessment of the cumulative error determined through the analysis has been made by comparing the values of the spatial gradients directly measured with the gradient estimated from the decay of kinetic energy. The main sources of error were found to be related to the length of the two control volumes and to the fitting range, as well as the function used to interpolate the correlation coefficient when the Taylor length scale (or({partial_derivative}u{sub i}/{partial_derivative}x{sub j}){sup 2}) are estimated. (orig.)
Keller, Jochen
2008-01-01
The thesis is considering aspects of SU(2) Yang-Mills thermodynamics in its deconfining high-temperature phase. We calculate the two-point correlation function of the energy density of the photon in a thermalized gas, at first in the conventional U(1) gauge theory, followed by a calculation, where the photon is identified with the massless gauge mode in deconfining SU(2) Yang-Mills thermodynamics. Apart from the fact, that this calculation is interesting from a technical point of view, we can consider several aspects of phenomenological relevance. Since we interpret the two-point correlator of energy density as a measure for the energy transfer, and thus for the electromagnetic interaction of microscopic objects, such as atoms immersed into a photon gas, we are able to give an explanation for the unexpected stability of cold, innergalactic clouds consisting of atomic hydrogen. Subsequently, we evaluate the spatial string tension in deconfining SU(2) Yang-Mills thermodynamics, which can be regarded as measure ...
McCarter, W. J.; Taha, H. M.; Suryanto, B.; Starrs, G.
2015-08-01
Ac impedance spectroscopy measurements are used to critically examine the end-to-end (two-point) testing technique employed in evaluating the bulk electrical resistivity of concrete. In particular, this paper focusses on the interfacial contact region between the electrode and specimen and the influence of contacting medium and measurement frequency on the impedance response. Two-point and four-point electrode configurations were compared and modelling of the impedance response was undertaken to identify and quantify the contribution of the electrode-specimen contact region on the measured impedance. Measurements are presented in both Bode and Nyquist formats to aid interpretation. Concretes mixes conforming to BSEN206-1 and BS8500-1 were investigated which included concretes containing the supplementary cementitious materials fly ash and ground granulated blast-furnace slag. A measurement protocol is presented for the end-to-end technique in terms of test frequency and electrode-specimen contacting medium in order to minimize electrode-specimen interfacial effect and ensure correct measurement of bulk resistivity.
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.
Two-Point Stress-Tensor Correlator in N=1 SYM(2+1)
Hiller, J R; Trittmann, U
2001-01-01
Recent advances in string theory have highlighted the need for reliable numerical methods to calculate correlators at strong coupling in supersymmetric theories. We present a calculation of the correlator in N=1 SYM theory in 2+1 dimensions. The numerical method we use is supersymmetric discrete light-cone quantization (SDLCQ), which preserves the supersymmetry at every order of the approximation and treats fermions and bosons on the same footing. This calculation is done at large $N_c$. For small and intermediate r the correlator converges rapidly for all couplings. At small r the correlator behaves like 1/r^6, as expected from conformal field theory. At large r the correlator is dominated by the BPS states of the theory. There is, however, a critical value of the coupling where the large-r correlator goes to zero, suggesting that the large-r correlator can only be trusted to some finite coupling which depends on the transverse resolution. We find that this critical coupling grows linearly with the square r...
Mapping Correlation of Two Point Sources in the Gamma-Ray Sky
Energy Technology Data Exchange (ETDEWEB)
Gibson, Alexander [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-08-20
The Fermi Gamma-Ray Space Telescope has been taking data on high energy photons or γ rays since June 11th, 2008, and people have been cataloging and profiling point sources of these γ rays ever since. After roughly one year of being in operation over 1400 sources were cataloged. Now, in 2015 we have 3033 sources cataloged. With the increasing amount of sources it’s important to think about the limitations of likelihood analysis for highly correlated sources. In this paper I will present the problems of using likelihood analysis for sources that are highly correlated as well as show under what circumstances sources can be considered highly correlated. Dark matter over densities may show up as a point source, so it is a necessary step to learn how the two signals will interact to allow for a proper search for dark matter.
Energy Technology Data Exchange (ETDEWEB)
Li, Xue; Cao, Jia; Du, Dajun [Shanghai Univ. (China). Key Lab. of Power Station Automation Technology
2013-07-01
This paper is concerned with the probabilistic optimal power flow (POPF) calculation including wind farms with correlated parameters which contains nodal injections. The two-point estimate method (2PEM) is employed to solve the POPF. Moreover, the correlation samples between nodal injections and line parameters are generated by Cholesky Factorization method. Simulation results show that 2PEM is feasible and effective to solve the POPF including wind farms with correlated parameters, while the 2PEM has higher computation precision and consume less CPU time than Monte Carlo Simulation.
Forecasts on neutrino mass constraints from the redshift-space two-point correlation function
Petracca, F.; Marulli, F.; Moscardini, L.; Cimatti, A.; Carbone, C.; Angulo, R. E.
2016-11-01
We provide constraints on the accuracy with which the neutrino mass fraction, fν, can be estimated when exploiting measurements of redshift-space distortions, describing in particular how the error on neutrino mass depends on three fundamental parameters of a characteristic galaxy redshift survey: density, halo bias and volume. In doing this, we make use of a series of dark matter halo catalogues extracted from the BASICC simulation. The mock data are analysed via a Markov Chain Monte Carlo likelihood analysis. We find a fitting function that well describes the dependence of the error on bias, density and volume, showing a decrease in the error as the bias and volume increase, and a decrease with density down to an almost constant value for high-density values. This fitting formula allows us to produce forecasts on the precision achievable with future surveys on measurements of the neutrino mass fraction. For example, a Euclid-like spectroscopic survey should be able to measure the neutrino mass fraction with an accuracy of δfν ≈ 3.1 × 10-3 (which is equivalent to δ∑mν ≈ 0.039eV), using redshift-space clustering once all the other cosmological parameters are kept fixed to the ΛCDM case.
Raccanelli, Alvise; Bertacca, Daniele; Jeong, Donghui; Neyrinck, Mark C.; Szalay, Alexander S.
2016-01-01
We study the parity-odd part (that we shall call Doppler term) of the linear galaxy two-point correlation function that arises from wide-angle, velocity, Doppler lensing and cosmic acceleration effects. As it is important at low redshift and at large angular separations, the Doppler term is usually neglected in the current generation of galaxy surveys. For future wide-angle galaxy surveys such as Euclid, SPHEREx and SKA, however, we show that the Doppler term must be included. The effect of t...
Giuricin, G; Girardi, M; Mezzetti, M; Marinoni, C; Giuricin, Giuliano; Samurovic, Srdjan; Girardi, Marisa; Mezzetti, Marino; Marinoni, Christian
2001-01-01
We use the two-point correlation function in redshift space, $\\xi(s)$, to study the clustering of the galaxies and groups of the Nearby Optical Galaxy (NOG) sample, which is a nearly all-sky, complete, magnitude-limited sample of $\\sim$7000 bright and nearby optical galaxies. The correlation function of galaxies is well described by a power law, $\\xi(s)=(s/s_0)^{-\\gamma}$, with slope $\\gamma\\sim1.5$ and $s_0\\sim6.4 h^{-1}$Mpc (on scales $2.7 - 12 h^{-1}$Mpc), in agreement with previous results of several redshift surveys of optical galaxies. We confirm the existence of morphological segregation between early- and late-type galaxies and, in particular, we find a gradual decreasing of the strength of clustering from the S0 galaxies to the late-type spirals, on intermediate scales. Furthermore, luminous galaxies turn out to be more clustered than dim galaxies. The luminosity segregation, which is significant for both early- and late-type objects, starts to become appreciable only for galaxies brighter than $M_B\\...
Teichrieb, Claudio A.; Acevedo, Otávio C.; Degrazia, Gervásio A.; Moraes, Osvaldo L. L.; Roberti, Débora R.; Zimermann, Hans R.; Santos, Daniel M.; Alves, Rita C. M.
2013-03-01
The study presents an analysis of two-point correlations between time series of nocturnal atmospheric wind, obtained from two micrometeorological towers, 45 m horizontally apart, each equipped with two sonic anemometers, 2.5 m vertically apart. It focuses on the scale dependence of the two-point correlations obtained from sensors vertically and horizontally separated. In particular, the role of low-frequency non-turbulent processes in the correlations is assessed, and compared to that of the turbulent scales of motion. The vertical correlations of the streamwise and vertical wind components show little dependence on the turbulence intensity, but those of the spanwise component decrease appreciably as it gets more turbulent. Multiresolution decomposition shows that the two-point correlations become increasingly dominated by low-frequency scales as it gets less turbulent, and that such large-scale processes are largely reduced in fully turbulent conditions. It is also shown that the vertical correlations of the spanwise wind component is negative for very small time scales. Horizontal two-point correlations obtained at the 45 m separation distance between the towers are almost entirely dominated by low-frequency motions, regardless of the turbulence intensity, but the magnitude of such correlations decreases with increasing turbulence intensity for any wind components. A comparison between the horizontal two-point correlations and autocorrelations taken with a time lag given by the ratio of the horizontal separation to the mean wind component in the direction that connects the two towers leads to the conclusion that the statistical properties of turbulence are often preserved over the horizontal distance, despite the lack of turbulence correlations for that separation.
van Daalen, Marcel P; McCarthy, Ian G; Booth, C M; Vecchia, Claudio Dalla
2013-01-01
The observed clustering of galaxies and the cross-correlation of galaxies and mass (a measure of galaxy-galaxy lensing) provide important constraints on both cosmology and models of galaxy formation. Even though the dissipation, and more importantly the feedback processes associated with galaxy formation are thought to affect the distribution of matter, essentially all models used to predict clustering data are based on dark matter only simulations. Here, we use large hydrodynamical simulations to investigate how galaxy formation affects the autocorrelation functions of galaxies, subhaloes, as well as their cross-correlation with matter. We show that the changes due to the inclusion of baryons are not limited to small scales and are even present in samples selected by subhalo mass. Samples selected by subhalo mass cluster ~10% more strongly in a baryonic run on scales r ~ 1Mpc/h or larger, and this difference increases for smaller separations. While the inclusion of baryons boosts the clustering at fixed subh...
Energy Technology Data Exchange (ETDEWEB)
Yoo, Hyun Suk; Lee, Jeong Min; Yoon, Jeong Hee; Lee, Dong Ho; Chang, Won; Han, Joon Koo [Seoul National University Hospital, Seoul (Korea, Republic of)
2016-09-15
To prospectively compare technical success rate and reliable measurements of virtual touch quantification (VTQ) elastography and elastography point quantification (ElastPQ), and to correlate liver stiffness (LS) measurements obtained by the two elastography techniques. Our study included 85 patients, 80 of whom were previously diagnosed with chronic liver disease. The technical success rate and reliable measurements of the two kinds of point shear wave elastography (pSWE) techniques were compared by χ{sup 2} analysis. LS values measured using the two techniques were compared and correlated via Wilcoxon signed-rank test, Spearman correlation coefficient, and 95% Bland-Altman limit of agreement. The intraobserver reproducibility of ElastPQ was determined by 95% Bland-Altman limit of agreement and intraclass correlation coefficient (ICC). The two pSWE techniques showed similar technical success rate (98.8% for VTQ vs. 95.3% for ElastPQ, p = 0.823) and reliable LS measurements (95.3% for VTQ vs. 90.6% for ElastPQ, p = 0.509). The mean LS measurements obtained by VTQ (1.71 ± 0.47 m/s) and ElastPQ (1.66 ± 0.41 m/s) were not significantly different (p = 0.209). The LS measurements obtained by the two techniques showed strong correlation (r = 0.820); in addition, the 95% limit of agreement of the two methods was 27.5% of the mean. Finally, the ICC of repeat ElastPQ measurements was 0.991. Virtual touch quantification and ElastPQ showed similar technical success rate and reliable measurements, with strongly correlated LS measurements. However, the two methods are not interchangeable due to the large limit of agreement.
Fu, Liping; Erben, Thomas; Heymans, Catherine; Hildebrandt, Hendrik; Hoekstra, Henk; Kitching, Thomas D; Mellier, Yannick; Miller, Lance; Semboloni, Elisabetta; Simon, Patrick; Van Waerbeke, Ludovic; Coupon, Jean; Harnois-Déraps, Joachim; Hudson, Michael J; Kuijken, Konrad; Rowe, Barnaby; Schrabback, Tim; Vafaei, Sanaz; Velander, Malin
2014-01-01
Higher-order, non-Gaussian aspects of the large-scale structure carry valuable information on structure formation and cosmology, which is complementary to second-order statistics. In this work we measure second- and third-order weak-lensing aperture-mass moments from CFHTLenS and combine those with CMB anisotropy probes. The third moment is measured with a significance of $2\\sigma$. The combined constraint on $\\Sigma_8 = \\sigma_8 (\\Omega_{\\rm m}/0.27)^\\alpha$ is improved by 10%, in comparison to the second-order only, and the allowed ranges for $\\Omega_{\\rm m}$ and $\\sigma_8$ are substantially reduced. Including general triangles of the lensing bispectrum yields tighter constraints compared to probing mainly equilateral triangles. Second- and third-order CFHTLenS lensing measurements improve Planck CMB constraints on $\\Omega_{\\rm m}$ and $\\sigma_8$ by 26% for flat $\\Lambda$CDM. For a model with free curvature, the joint CFHTLenS-Planck result is $\\Omega_{\\rm m} = 0.28 \\pm 0.02$ (68% confidence), which is an i...
Tong, Jonathan; Mao, Oliver; Goldreich, Daniel
2013-01-01
Two-point discrimination is widely used to measure tactile spatial acuity. The validity of the two-point threshold as a spatial acuity measure rests on the assumption that two points can be distinguished from one only when the two points are sufficiently separated to evoke spatially distinguishable foci of neural activity. However, some previous research has challenged this view, suggesting instead that two-point task performance benefits from an unintended non-spatial cue, allowing spuriously good performance at small tip separations. We compared the traditional two-point task to an equally convenient alternative task in which participants attempt to discern the orientation (vertical or horizontal) of two points of contact. We used precision digital readout calipers to administer two-interval forced-choice versions of both tasks to 24 neurologically healthy adults, on the fingertip, finger base, palm, and forearm. We used Bayesian adaptive testing to estimate the participants' psychometric functions on the two tasks. Traditional two-point performance remained significantly above chance levels even at zero point separation. In contrast, two-point orientation discrimination approached chance as point separation approached zero, as expected for a valid measure of tactile spatial acuity. Traditional two-point performance was so inflated at small point separations that 75%-correct thresholds could be determined on all tested sites for fewer than half of participants. The 95%-correct thresholds on the two tasks were similar, and correlated with receptive field spacing. In keeping with previous critiques, we conclude that the traditional two-point task provides an unintended non-spatial cue, resulting in spuriously good performance at small spatial separations. Unlike two-point discrimination, two-point orientation discrimination rigorously measures tactile spatial acuity. We recommend the use of two-point orientation discrimination for neurological assessment.
Directory of Open Access Journals (Sweden)
Jonathan eTong
2013-09-01
Full Text Available Two-point discrimination is widely used to measure tactile spatial acuity. The validity of the two-point threshold as a spatial acuity measure rests on the assumption that two points can be distinguished from one only when the two points are sufficiently separated to evoke spatially distinguishable foci of neural activity. However, some previous research has challenged this view, suggesting instead that two-point task performance benefits from an unintended non-spatial cue, allowing spuriously good performance at small tip separations. We compared the traditional two-point task to an equally convenient alternative task in which participants attempt to discern the orientation (vertical or horizontal of two points of contact. We used precision digital readout calipers to administer two-interval forced-choice versions of both tasks to 24 neurologically healthy adults, on the fingertip, finger base, palm, and forearm. We used Bayesian adaptive testing to estimate the participants’ psychometric functions on the two tasks. Traditional two-point performance remained significantly above chance levels even at zero point separation. In contrast, two-point orientation discrimination approached chance as point separation approached zero, as expected for a valid measure of tactile spatial acuity. Traditional two-point performance was so inflated at small point separations that 75%-correct thresholds could be determined on all tested sites for fewer than half of participants. The 95%-correct thresholds on the two tasks were similar, and correlated with receptive field spacing. In keeping with previous critiques, we conclude that the traditional two-point task provides an unintended non-spatial cue, resulting in spuriously good performance at small spatial separations. Unlike two-point discrimination, two-point orientation discrimination rigorously measures tactile spatial acuity. We recommend the use of two-point orientation discrimination for neurological
Capri, M A L; Pereira, A D; Fiorentini, D; Guimaraes, M S; Mintz, B W; Palhares, L F; Sorella, S P
2016-01-01
In order to construct a gauge invariant two-point function in a Yang-Mills theory, we propose the use of the all-order gauge invariant transverse configurations A^h. Such configurations can be obtained through the minimization of the functional A^2_{min} along the gauge orbit within the BRST invariant formulation of the Gribov-Zwanziger framework recently put forward in [1,2] for the class of the linear covariant gauges. This correlator turns out to provide a characterization of non-perturbative aspects of the theory in a BRST invariant and gauge parameter independent way. In particular, it turns out that the poles of are the same as those of the transverse part of the gluon propagator, which are also formally shown to be independent of the gauge parameter entering the gauge condition through the Nielsen identities. The latter follow from the new exact BRST invariant formulation introduced before. Moreover, the correlator enables us to attach a BRST invariant meaning to the possible positivity violation of ...
Packard, René R Sevag; Zhang, XiaoXiao; Luo, Yuan; Ma, Teng; Jen, Nelson; Ma, Jianguo; Demer, Linda L; Zhou, Qifa; Sayre, James W; Li, Rongsong; Tai, Yu-Chong; Hsiai, Tzung K
2016-09-01
Four-point electrode systems are commonly used for electric impedance measurements of biomaterials and tissues. We introduce a 2-point system to reduce electrode polarization for heterogeneous measurements of vascular wall. Presence of endoluminal oxidized low density lipoprotein (oxLDL) and lipids alters the electrochemical impedance that can be measured by electrochemical impedance spectroscopy (EIS). We developed a catheter-based 2-point micro-electrode configuration for intravascular deployment in New Zealand White rabbits. An array of 2 flexible round electrodes, 240 µm in diameter and separated by 400 µm was microfabricated and mounted on an inflatable balloon catheter for EIS measurement of the oxLDL-rich lesions developed as a result of high-fat diet-induced hyperlipidemia. Upon balloon inflation, the 2-point electrode array conformed to the arterial wall to allow deep intraplaque penetration via alternating current (AC). The frequency sweep from 10 to 300 kHz generated an increase in capacitance, providing distinct changes in both impedance (Ω) and phase (ϕ) in relation to varying degrees of intraplaque lipid burden in the aorta. Aortic endoluminal EIS measurements were compared with epicardial fat tissue and validated by intravascular ultrasound and immunohistochemistry for plaque lipids and foam cells. Thus, we demonstrate a new approach to quantify endoluminal EIS via a 2-point stretchable electrode strategy.
Mo, Jie-Xiong; Lin, Ze-Tao; Zeng, Xiao-Xiong
2016-01-01
To gain holographic insight into critical phenomena of $f(R)$ AdS black holes, we investigate their two point correlation function, which are dual to the geodesic length in the bulk. We solve the equation of motion constrained by the boundary condition numerically and probe both the effect of boundary region size and $f(R)$ gravity. Moreover, we introduce an analogous specific heat related to $\\delta L$. It is shown in the $T-\\delta L$ graph for the case $Q
Dudok de Wit, T; Dunlop, M; Luehr, H
1999-01-01
A framework is described for estimating Linear growth rates and spectral energy transfers in turbulent wave-fields using two-point measurements. This approach, which is based on Volterra series, is applied to dual satellite data gathered in the vicinity of the Earth's bow shock, where Short Large Amplitude Magnetic Structures (SLAMS) supposedly play a leading role. The analysis attests the dynamic evolution of the SLAMS and reveals an energy cascade toward high-frequency waves.
Revisiting van der Waals like behavior of f(R AdS black holes via the two point correlation function
Directory of Open Access Journals (Sweden)
Jie-Xiong Mo
2017-05-01
Full Text Available Van der Waals like behavior of f(R AdS black holes is revisited via two point correlation function, which is dual to the geodesic length in the bulk. The equation of motion constrained by the boundary condition is solved numerically and both the effect of boundary region size and f(R gravity are probed. Moreover, an analogous specific heat related to δL is introduced. It is shown that the T−δL graphs of f(R AdS black holes exhibit reverse van der Waals like behavior just as the T−S graphs do. Free energy analysis is carried out to determine the first order phase transition temperature T⁎ and the unstable branch in T−δL curve is removed by a bar T=T⁎. It is shown that the first order phase transition temperature is the same at least to the order of 10−10 for different choices of the parameter b although the values of free energy vary with b. Our result further supports the former finding that charged f(R AdS black holes behave much like RN-AdS black holes. We also check the analogous equal area law numerically and find that the relative errors for both the cases θ0=0.1 and θ0=0.2 are small enough. The fitting functions between log|T−Tc| and log|δL−δLc| for both cases are also obtained. It is shown that the slope is around 3, implying that the critical exponent is about 2/3. This result is in accordance with those in former literatures of specific heat related to the thermal entropy or entanglement entropy.
Two-point optical coherency matrix tomography.
Abouraddy, Ayman F; Kagalwala, Kumel H; Saleh, Bahaa E A
2014-04-15
The two-point coherence of an electromagnetic field is represented completely by a 4×4 coherency matrix G that encodes the joint polarization-spatial-field correlations. Here, we describe a systematic sequence of cascaded spatial and polarization projective measurements that are sufficient to tomographically reconstruct G--a task that, to the best of our knowledge, has not yet been realized. Our approach benefits from the correspondence between this reconstruction problem in classical optics and that of quantum state tomography for two-photon states in quantum optics. Identifying G uniquely determines all the measurable correlation characteristics of the field and, thus, lifts ambiguities that arise from reliance on traditional scalar descriptors, especially when the field's degrees of freedom are correlated or classically entangled.
Quantum correlations and measurements
Energy Technology Data Exchange (ETDEWEB)
Sperling, Jan
2015-07-16
The present thesis is a state of the art report on the characterization techniques and measurement strategies to verify quantum correlations. I mainly focus on research which has been performed in the theoretical quantum optics group at the University of Rostock during the last few years. The results include theoretical findings and analysis of experimental studies of radiation fields. We investigate the verification of quantum properties, the quantification of these quantum effects, and the characterization of quantum optical detector systems.
Two-Point Fuzzy Ostrowski Type Inequalities
Directory of Open Access Journals (Sweden)
Muhammad Amer Latif
2013-08-01
Full Text Available Two-point fuzzy Ostrowski type inequalities are proved for fuzzy Hölder and fuzzy differentiable functions. The two-point fuzzy Ostrowski type inequality for M-lipshitzian mappings is also obtained. It is proved that only the two-point fuzzy Ostrowski type inequality for M-lipshitzian mappings is sharp and as a consequence generalize the two-point fuzzy Ostrowski type inequalities obtained for fuzzy differentiable functions.
Eddy Correlation Flux Measurement System
Oak Ridge National Laboratory — The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat,...
Correlation measurement of squeezed light
DEFF Research Database (Denmark)
Krivitsky, Leonid; Andersen, Ulrik Lund; Dong, R.;
2009-01-01
We study the implementation of a correlation measurement technique for the characterization of squeezed light which is nearly free of electronic noise. With two different sources of squeezed light, we show that the sign of the covariance coefficient, revealed from the time-resolved correlation data...
Holographic Two-Point Functions in Conformal Gravity
Ghodsi, Ahmad; Naseh, Ali
2014-01-01
In this paper we compute the holographic two-point functions of four dimensional conformal gravity. Precisely we calculate the two-point functions for Energy-Momentum (EM) and Partially Massless Response (PMR) operators that have been identified as two response functions for two independent sources in the dual CFT. The correlation function of EM with PMR tensors turns out to be zero which is expected according to the conformal symmetry. The two-point function of EM is that of a transverse and traceless tensor, and the two-point function of PMR which is a traceless operator contains two distinct parts, one for a transverse-traceless tensor operator and another one for a vector field, both of which fulfill criteria of a CFT. We also discuss about the unitarity of the theory.
Two Point Pade Approximants and Duality
Banks, Tom
2013-01-01
We propose the use of two point Pade approximants to find expressions valid uniformly in coupling constant for theories with both weak and strong coupling expansions. In particular, one can use these approximants in models with a strong/weak duality, when the symmetries do not determine exact expressions for some quantity.
EARLINET Correlative Measurements For CALIPSO
Pappalardo, G.
2006-12-01
EARLINET, the European Aerosol Research Lidar Network, is the first aerosol lidar network, established in 2000, with the main goal to provide a comprehensive, quantitative, and statistically significant data base for the aerosol distribution on a continental scale. At present, 24 stations distributed over Europe are part of the network: 10 single backscatter lidar stations, 7 Raman lidar stations with the Raman channel in the UV for independent measurements of aerosol extinction and backscatter, and 7 multi-wavelength Raman lidar stations (elastic channel at 1064 nm, 532 nm, 355 nm, Raman channels at 532 nm and 355 nm, plus depolarization channel at 532 nm) for the retrieval of aerosol microphysical properties. The network activity is based on scheduled measurements, a rigorous quality assurance program addressing both instruments and evaluation algorithms, and a standardized data exchange format. In order to collect unbiased data, all the network stations perform measurements simultaneously at three fixed dates a week. Lidar observations are performed on a regular schedule of one daytime measurement on Monday around noon, when the boundary layer is usually well developed, and two night time measurements per week (Monday and Thursday), with low background light, in order to perform Raman extinction measurements. Additional network measurements are performed to address specifically important processes that are localized either in space or time, like Saharan dust outbreaks, forest fires, volcanic eruptions, photochemical smog. EARLINET represents an optimal tool to validate CALIPSO lidar data and to provide the necessary information to fully exploit the information from that mission. In particular, aerosol extinction measurements, provided by the network, will be important for the aerosol retrievals from the CALIPSO backscatter lidar. EARLINET started correlative measurements for CALIPSO since 14 June 2006. These EARLINET correlative measurements are performed at
Optimal measurements for nonlocal correlations
Schwarz, Sacha; Stefanov, André; Wolf, Stefan; Montina, Alberto
2016-08-01
A problem in quantum information theory is to find the experimental setup that maximizes the nonlocality of correlations with respect to some suitable measure such as the violation of Bell inequalities. There are however some complications with Bell inequalities. First and foremost it is unfeasible to determine the whole set of Bell inequalities already for a few measurements and thus unfeasible to find the experimental setup maximizing their violation. Second, the Bell violation suffers from an ambiguity stemming from the choice of the normalization of the Bell coefficients. An alternative measure of nonlocality with a direct information-theoretic interpretation is the minimal amount of classical communication required for simulating nonlocal correlations. In the case of many instances simulated in parallel, the minimal communication cost per instance is called nonlocal capacity, and its computation can be reduced to a convex-optimization problem. This quantity can be computed for a higher number of measurements and turns out to be useful for finding the optimal experimental setup. Focusing on the bipartite case, we present a simple method for maximizing the nonlocal capacity over a given configuration space and, in particular, over a set of possible measurements, yielding the corresponding optimal setup. Furthermore, we show that there is a functional relationship between Bell violation and nonlocal capacity. The method is illustrated with numerical tests and compared with the maximization of the violation of CGLMP-type Bell inequalities on the basis of entangled two-qubit as well as two-qutrit states. Remarkably, the anomaly of nonlocality displayed by qutrits turns out to be even stronger if the nonlocal capacity is employed as a measure of nonlocality.
Turbulent correlation measurements in a two-stream mixing layer.
Jones, B. G.; Planchon, H. P.; Hammersley, R. J.
1973-01-01
Two point space-time measurements of the axial component of fluctuating velocity were made using linearized hot-wire anemometry. Space scales, convected frame correlations and time scales, and convection velocities in the shear layer were evaluated. Both filtered narrow and broad band convected frame autocorrelations were determined. Differences between axial broad band convection velocities and both mean turbulence and mean entrained fluid velocities were observed. Scaled broad band convection velocities for the mixing layer and simple round jets were found to collapse to a common curve. Axial narrow band convection velocities showed strong frequency and transverse position dependence.
WenJun Zhang; Xin Li
2015-01-01
Between-taxon interactions can be detected by calculating the sampling data of taxon sample type. In present study, Spearman rank correlation and proportion correlation are chosen as the general correlation measures, and their partial correlations are calculated and compared. The results show that for Spearman rank correlation measure, in all predicted candidate direct interactions by partial correlation, about 16.77% (x, 0-45.4%) of them are not successfully detected by Spearman rank correla...
Correlation Measurements on Small Mobile Devices
DEFF Research Database (Denmark)
Yanakiev, Boyan Radkov; Nielsen, Jesper Ødum; Christensen, Morten
2012-01-01
Here, analysis of the antenna correlation at the design stage is done, with focus on measurement techniques. Various theoretical definitions of correlations are used with the corresponding measured data required. The problems related to the coaxial measurement cables, when calculating correlation...
Correlated measurement error hampers association network inference.
Kaduk, Mateusz; Hoefsloot, Huub C J; Vis, Daniel J; Reijmers, Theo; van der Greef, Jan; Smilde, Age K; Hendriks, Margriet M W B
2014-09-01
Modern chromatography-based metabolomics measurements generate large amounts of data in the form of abundances of metabolites. An increasingly popular way of representing and analyzing such data is by means of association networks. Ideally, such a network can be interpreted in terms of the underlying biology. A property of chromatography-based metabolomics data is that the measurement error structure is complex: apart from the usual (random) instrumental error there is also correlated measurement error. This is intrinsic to the way the samples are prepared and the analyses are performed and cannot be avoided. The impact of correlated measurement errors on (partial) correlation networks can be large and is not always predictable. The interplay between relative amounts of uncorrelated measurement error, correlated measurement error and biological variation defines this impact. Using chromatography-based time-resolved lipidomics data obtained from a human intervention study we show how partial correlation based association networks are influenced by correlated measurement error. We show how the effect of correlated measurement error on partial correlations is different for direct and indirect associations. For direct associations the correlated measurement error usually has no negative effect on the results, while for indirect associations, depending on the relative size of the correlated measurement error, results can become unreliable. The aim of this paper is to generate awareness of the existence of correlated measurement errors and their influence on association networks. Time series lipidomics data is used for this purpose, as it makes it possible to visually distinguish the correlated measurement error from a biological response. Underestimating the phenomenon of correlated measurement error will result in the suggestion of biologically meaningful results that in reality rest solely on complicated error structures. Using proper experimental designs that allow
Criteria for measures of quantum correlations
Brodutch, Aharon
2011-01-01
Entanglement does not describe all quantum correlations and several authors have shown the need to go beyond entanglement when dealing with mixed states. Several different measures have sprung up in the literature, for a variety of reasons, To describe quantum correlations; some are known under the collective name quantum discord. Yet, in the same sprit as the criteria for entanglement measures, there is no general mechanism that determines whether a measure of quantum and classical correlations is a proper measure of correlations. This is partially due to the fact that the answer is a bit muddy. In this article we attempt tackle this muddy topic by writing down several criteria for a "good" measure of correlations. We breakup our list into necessary, reasonable, and debatable conditions. We then proceed to prove several of these conditions for generalized measures of quantum correlations. However, not all conditions are met by all measures; we show this via several examples. The reasonable conditions are rel...
Institute of Scientific and Technical Information of China (English)
MALLICK Mahendra; LA SCALA Barbara
2008-01-01
We consider the problem of initializing the tracking filter of a target moving with nearly constant velocity when positiononly (1D, 2D, or 3D) measurements are available. It is known that the Kalman filter is optimal for such a problem, provided it is correctly initialized. We compare a single-point and the well-known two-point difference track initialization algorithms. We analytically show that if the process noise approaches zero and the maximum speed of a target used to initialize the velocity variance approaches infinity, then the single-point algorithm reduces to the two-point difference algorithm. We present numerical results that show that the single-point algorithm performs consistently better than the two-point difference algorithm in the mean square error sense. We also present analytical results that support the conjecture that this is true in general.
Surface Wear Measurement Using Optical Correlation Technique
Acinger, Kresimir
1983-12-01
The coherent optical correlation technique was applied for measuring the surface wear of a tappet (part of car engine), worn by friction with the camshaft. It was found that maximum correlation intensity decays exponentially with the number of wear cycles (i.e. camshaft revolutions). Tappets of the same make have an identical rate of correlation decay. Tappets of different makes have different rates of correlation decay which are in agreement with observed long term wear.
Integral correlation measures for multiparticle physics
Eggers, H C; Carruthers, Peter A; Buschbeck, Brigitte
1993-01-01
We report on a considerable improvement in the technique of measuring multiparticle correlations via integrals over correlation functions. A modification of measures used in the characterization of chaotic dynamical sytems permits fast and flexible calculation of factorial moments and cumulants as well as their differential versions. Higher order correlation integral measurements even of large multiplicity events such as encountered in heavy ion collisons are now feasible. The change from ``ordinary'' to ``factorial'' powers may have important consequences in other fields such as the study of galaxy correlations and Bose-Einstein interferometry.
Correlation and Sequential Filtering with Doppler Measurements
Institute of Scientific and Technical Information of China (English)
WANGJianguo; HEPeikun; HANYueqiu; WUSiliang
2004-01-01
Two sequential filters are developed for Doppler radar measurements in the presence of correlation between range and range rate measurement errors. Two ideal linear measurement equations with the pseudo measurements are constructed via block-partitioned Cholesky factorization and the practical measurement equationswith the pseudo measurements are obtained through the direction cosine estimation and error compensation. The resulting sequential filters make the position measurement be possibly processed before the pseudo measurement and hence the more accurate direction cosine estimate can be obtained from the filtered position estimate rather than the predicted state estimate. The numerical simulations with different rangerange rate correlation coefficients show thatthe proposed two sequential filters are almost equivalent in performance but both superior to the conventional extended Kalman filter for different correlation coefficients.
Unified entropic measures of quantum correlations induced by local measurements
Bosyk, G. M.; Bellomo, G.; Zozor, S.; Portesi, M.; Lamberti, P. W.
2016-11-01
We introduce quantum correlation measures based on the minimal change in unified entropies induced by local rank-one projective measurements, divided by a factor that depends on the generalized purity of the system in the case of nonadditive entropies. In this way, we overcome the issue of the artificial increasing of the value of quantum correlation measures based on nonadditive entropies when an uncorrelated ancilla is appended to the system, without changing the computability of our entropic correlation measures with respect to the previous ones. Moreover, we recover as limiting cases the quantum correlation measures based on von Neumann and Rényi entropies (i.e., additive entropies), for which the adjustment factor becomes trivial. In addition, we distinguish between total and semiquantum correlations and obtain some inequalities between them. Finally, we obtain analytical expressions of the entropic correlation measures for typical quantum bipartite systems.
On the measurability of quantum correlation functions
Energy Technology Data Exchange (ETDEWEB)
Lima Bernardo, Bertúlio de, E-mail: bertulio.fisica@gmail.com; Azevedo, Sérgio; Rosas, Alexandre
2015-05-15
The concept of correlation function is widely used in classical statistical mechanics to characterize how two or more variables depend on each other. In quantum mechanics, on the other hand, there are observables that cannot be measured at the same time; the so-called incompatible observables. This prospect imposes a limitation on the definition of a quantum analog for the correlation function in terms of a sequence of measurements. Here, based on the notion of sequential weak measurements, we circumvent this limitation by introducing a framework to measure general quantum correlation functions, in principle, independently of the state of the system and the operators involved. To illustrate, we propose an experimental configuration to obtain explicitly the quantum correlation function between two Pauli operators, in which the input state is an arbitrary mixed qubit state encoded on the polarization of photons.
Measurements of Correlation-Enhanced Collision Rates
Anderegg, F.; Dubin, D. H. E.; O'Neil, T. M.; Driscoll, C. F.
2008-11-01
We measure the perp-to-parallel collision rate ν| in laser-cooled Magnesium ion plasmas in the strongly-magnetized and correlated regime; and obtain close agreement with the ``Salpeter correlation enhancement'' first studied for fusion in dense plasmas such as stars. The cyclotron energy, like nuclear energy, is released only through rare close-range collisions. These close collisions are suppressed by strong magnetization, because collisional impact distances are rarely as small as a cyclotron radius rc. However, theory predicts that particle correlations reduce this suppression of collisionality, enhancing the rare close collisions by e^γ, where γ≡e^2 / aT is the correlation parameter. We control the plasma temperature over the range 4 0-6 < T < 1eV, giving correlation parameters up to γ 0, with measured collision rates 2 < ν| 2 10^4 sec-1. At low temperatures, the measured ν| are enhanced by up to 10^9 compared to uncorrelated theory, consistent with the predicted correlation enhancement. When the plasma density is reduced from 2 to 0.12 x10^7cm-3, the correlations are eliminated and the measured ν| agree with uncorrelated theory. E.E. Salpeter and H.M. Van Horn, Astrophys. J. 155, 183 (1969). D.H.E. Dubin, Phys. Rev. Lett. 94, 025002 (2005).
Correlation Measure Equivalence in Dynamic Causal Structures
Gyongyosi, Laszlo
2016-01-01
We prove an equivalence transformation between the correlation measure functions of the causally-unbiased quantum gravity space and the causally-biased standard space. The theory of quantum gravity fuses the dynamic (nonfixed) causal structure of general relativity and the quantum uncertainty of quantum mechanics. In a quantum gravity space, the events are causally nonseparable and all time bias vanishes, which makes it no possible to use the standard causally-biased entropy and the correlation measure functions. Since a corrected causally-unbiased entropy function leads to an undefined, obscure mathematical structure, in our approach the correction is made in the data representation of the causally-unbiased space. We prove that the standard causally-biased entropy function with a data correction can be used to identify correlations in dynamic causal structures. As a corollary, all mathematical properties of the causally-biased correlation measure functions are preserved in the causally-unbiased space. The eq...
Finite-size scaling of two-point statistics and the turbulent energy cascade generators.
Cleve, Jochen; Dziekan, Thomas; Schmiegel, Jürgen; Barndorff-Nielsen, Ole E; Pearson, Bruce R; Sreenivasan, Katepalli R; Greiner, Martin
2005-02-01
Within the framework of random multiplicative energy cascade models of fully developed turbulence, finite-size-scaling expressions for two-point correlators and cumulants are derived, taking into account the observationally unavoidable conversion from an ultrametric to an Euclidean two-point distance. The comparison with two-point statistics of the surrogate energy dissipation, extracted from various wind tunnel and atmospheric boundary layer records, allows an accurate deduction of multiscaling exponents and cumulants, even at moderate Reynolds numbers for which simple power-law fits are not feasible. The extracted exponents serve as input for parametric estimates of the probabilistic cascade generator. Various cascade generators are evaluated.
Approach to the origin of turbulence on the basis of two-point kinetic theory
Tsuge, S.
1974-01-01
Equations for the fluctuation correlation in an incompressible shear flow are derived on the basis of kinetic theory, utilizing the two-point distribution function which obeys the BBGKY hierarchy equation truncated with the hypothesis of 'ternary' molecular chaos. The step from the molecular to the hydrodynamic description is accomplished by a moment expansion which is a two-point version of the thirteen-moment method, and which leads to a series of correlation equations, viz., the two-point counterparts of the continuity equation, the Navier-Stokes equation, etc. For almost parallel shearing flows the two-point equation is separable and reduces to two Orr-Sommerfeld equations with different physical implications.
Eddy Correlation Flux Measurement System (ECOR) Handbook
Energy Technology Data Exchange (ETDEWEB)
Cook, DR
2011-01-31
The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration.
Subnanosecond spectral diffusion measurement using photon correlation
Sallen, Gregory; Aichele, Thomas; André, Régis; Besombes, Lucien; Bougerol, Catherine; Richard, Maxime; Tatarenko, Serge; Kheng, Kuntheak; Poizat, Jean-Philippe; 10.1038/nphoton.2010.174
2012-01-01
Spectral diffusion is a result of random spectral jumps of a narrow line as a result of a fluctuating environment. It is an important issue in spectroscopy, because the observed spectral broadening prevents access to the intrinsic line properties. However, its characteristic parameters provide local information on the environment of a light emitter embedded in a solid matrix, or moving within a fluid, leading to numerous applications in physics and biology. We present a new experimental technique for measuring spectral diffusion based on photon correlations within a spectral line. Autocorrelation on half of the line and cross-correlation between the two halves give a quantitative value of the spectral diffusion time, with a resolution only limited by the correlation set-up. We have measured spectral diffusion of the photoluminescence of a single light emitter with a time resolution of 90 ps, exceeding by four orders of magnitude the best resolution reported to date.
γ - γ Angular Correlation Measurements With GRIFFIN
Maclean, Andrew; Griffin Collaboration
2015-10-01
When an excited nuclear state emits successive γ-rays causing a γ - γ cascade an anisotropy is found in the spatial distribution of γ2 with respect to γ1. Defining the direction of γ1 as the z-axis, the intermediate level, in general will have an uneven distribution of m-states. This causes an anisotropy in the angular correlation of the second γ-ray with respect to the first. These angular correlations are expressed by the W (θ) that depends on numerical coefficients described by the sequence of spin-parity values for the nuclear states involved, the multipolarities and mixing ratios. Angular correlations can be used for the assignment of spins and parities for the nuclear states, and thus provide a powerful means to elucidate the structure of nuclei far from stability through β - γ - γ coincidence measurements. In order to explore the sensitivity of the new 16 clover-detector GRIFFIN γ-ray spectrometer at TRIUMF-ISAC to such γ - γ angular correlations, and to optimize its performance for these measurements we have studied a well known γ - γ cascade from 60Co decay through both experimental measurements and Geant4 simulation. Results will be shown in this talk. Work supported by the Canada Foundation for Innovation, the Natural Sciences and Engineering Research Council of Canada and the National Research Council of Canada.
Measuring magnetic correlations in nanoparticle assemblies
DEFF Research Database (Denmark)
Beleggia, Marco; Frandsen, Cathrine
2014-01-01
We illustrate how to extract correlations between magnetic moments in assemblies of nanoparticles from, e.g., electron holography data providing the combined knowledge of particle size distribution, inter-particle distances, and magnitude and orientation of each magnetic moment within...... a nanoparticle superstructure, We show, based on simulated data, how to build a radial/angular pair distribution function f(r,θ) encoding the spatial and angular difference between every pair of magnetic moments. A scatter-plot of f(r,θ) reveals the degree of structural and magnetic order present, and hence...... provides a measure of the strength and range of magnetic correlations....
Constraining the Correlation Distance in Quantum Measurements
Schneider, Jean
2010-01-01
Standard Quantum Physics states that the outcome of measurements for some distant entangled subsystems are instantaneously statistically correlated, whatever their mutual distance. This correlation presents itself as if there were a correlation at a distance with infinite speed. It is expressed by the Bell Theorem. It has been experimentally verified over distances up to 18 km with a time resolution of a few picosecond, which can be translated into an apparent effective correlation speed larger than 10^7 c. The purpose of the present White Paper is to discuss the scientific interest and the feasibility to extend the correlation distance up to the Earth-Moon distance, i.e. 2 10^4 times larger than in present experiments. We are thus led to propose to install on the Moon a polarimter and a high performance photon detector with a high temporal resolution. Such an exploratory experiment would provide new tests of Quantum Physics and could perhaps discriminate between standard Quantum Physics and for instance the ...
Correlation function as a measure of the structure
Buryak, O.; Doroshkevich, A.
1995-01-01
Geometrical model of structure of the universe is examined to obtain analytical expression for the two points nonlinear correlation function. According to the model the objects (galaxies) are concentrated into two types of structure elements - filaments and sheets. We considered the filaments ( similar to galaxy filaments ) simply as straight lines and the sheets ( similar to superclusters of galaxies ) simply as planes. The homogeneously distributed objects are also taken into consideration....
Cosmological Measurements with General Relativistic Galaxy Correlations
Raccanelli, Alvise; Bertacca, Daniele; Doré, Olivier; Durrer, Ruth
2015-01-01
We investigate the cosmological dependence and the constraining power of large-scale galaxy correlations, including all redshift-distortions, wide-angle, lensing and gravitational potential effects on linear scales. We analyze the cosmological information present in the lensing convergence and in the gravitational potential terms describing the so-called "relativistic effects," and we find that, while smaller than the information contained in intrinsic galaxy clustering, it is not negligible. We investigate how neglecting them does bias cosmological measurements performed by future spectroscopic and photometric large-scale surveys such as SKA and Euclid. We perform a Fisher analysis using the CLASS code, modified to include scale-dependent galaxy bias and redshift-dependent magnification and evolution bias. Our results show that neglecting relativistic terms introduces an error in the forecasted precision in measuring cosmological parameters of the order of a few tens of percent, in particular when measuring ...
Eddy Correlation Flux Measurement System Handbook
Energy Technology Data Exchange (ETDEWEB)
Cook, D. R. [Argonne National Lab. (ANL), Argonne, IL (United States)
2016-01-01
The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration. The instruments used are: • a fast-response, three-dimensional (3D) wind sensor (sonic anemometer) to obtain the orthogonal wind components and the speed of sound (SOS) (used to derive the air temperature) • an open-path infrared gas analyzer (IRGA) to obtain the water vapor density and the CO2 concentration, and • an open-path infrared gas analyzer (IRGA) to obtain methane density and methane flux at one SGP EF and at the NSA CF. The ECOR systems are deployed at the locations where other methods for surface flux measurements (e.g., energy balance Bowen ratio [EBBR] systems) are difficult to employ, primarily at the north edge of a field of crops. A Surface Energy Balance System (SEBS) has been installed collocated with each deployed ECOR system in SGP, NSA, Tropical Western Pacific (TWP), ARM Mobile Facility 1 (AMF1), and ARM Mobile Facility 2 (AMF2). The surface energy balance system consists of upwelling and downwelling solar and infrared radiometers within one net radiometer, a wetness sensor, and soil measurements. The SEBS measurements allow the comparison of ECOR sensible and latent heat fluxes with the energy balance determined from the SEBS and provide information on wetting of the sensors for data quality purposes. The SEBS at one SGP and one NSA site also support upwelling and downwelling PAR measurements to qualify those two locations as Ameriflux sites.
Computational complexity for the two-point block method
See, Phang Pei; Majid, Zanariah Abdul
2014-12-01
In this paper, we discussed and compared the computational complexity for two-point block method and one-point method of Adams type. The computational complexity for both methods is determined based on the number of arithmetic operations performed and expressed in O(n). These two methods will be used to solve two-point second order boundary value problem directly and implemented using variable step size strategy adapted with the multiple shooting technique via three-step iterative method. Two numerical examples will be tested. The results show that the computational complexity of these methods is reliable to estimate the cost of these methods in term of the execution time. We conclude that the two-point block method has better computational performance compare to the one-point method as the total number of steps is larger.
Eddy correlation measurements of submarine groundwater discharge
Crusius, J.; Berg, P.; Koopmans, D.J.; Erban, L.
2008-01-01
This paper presents a new, non-invasive means of quantifying groundwater discharge into marine waters using an eddy correlation approach. The method takes advantage of the fact that, in virtually all aquatic environments, the dominant mode of vertical transport near the sediment-water interface is turbulent mixing. The technique thus relies on measuring simultaneously the fluctuating vertical velocity using an acoustic Doppler velocimeter and the fluctuating salinity and/or temperature using rapid-response conductivity and/or temperature sensors. The measurements are typically done at a height of 5-15??cm above the sediment surface, at a frequency of 16 to 64??Hz, and for a period of 15 to 60??min. If the groundwater salinity and/or temperature differ from that of the water column, the groundwater specific discharge (cm d- 1) can be quantified from either a heat or salt balance. Groundwater discharge was estimated with this new approach in Salt Pond, a small estuary on Cape Cod (MA, USA). Estimates agreed well with previous estimates of discharge measured using seepage meters and 222Rn as a tracer. The eddy correlation technique has several desirable characteristics: 1) discharge is quantified under in-situ hydrodynamic conditions; 2) salinity and temperature can serve as two semi-independent tracers of discharge; 3) discharge can be quantified at high temporal resolution, and 4) long-term records of discharge may be possible, due to the low power requirements of the instrumentation. ?? 2007 Elsevier B.V. All rights reserved.
Measures and applications of quantum correlations
Adesso, Gerardo; Bromley, Thomas R.; Cianciaruso, Marco
2016-11-01
Quantum information theory is built upon the realisation that quantum resources like coherence and entanglement can be exploited for novel or enhanced ways of transmitting and manipulating information, such as quantum cryptography, teleportation, and quantum computing. We now know that there is potentially much more than entanglement behind the power of quantum information processing. There exist more general forms of non-classical correlations, stemming from fundamental principles such as the necessary disturbance induced by a local measurement, or the persistence of quantum coherence in all possible local bases. These signatures can be identified and are resilient in almost all quantum states, and have been linked to the enhanced performance of certain quantum protocols over classical ones in noisy conditions. Their presence represents, among other things, one of the most essential manifestations of quantumness in cooperative systems, from the subatomic to the macroscopic domain. In this work we give an overview of the current quest for a proper understanding and characterisation of the frontier between classical and quantum correlations (QCs) in composite states. We focus on various approaches to define and quantify general QCs, based on different yet interlinked physical perspectives, and comment on the operational significance of the ensuing measures for quantum technology tasks such as information encoding, distribution, discrimination and metrology. We then provide a broader outlook of a few applications in which quantumness beyond entanglement looks fit to play a key role.
Two-point functions on deformed space-time
Trampetic, Josip
2014-01-01
We present a review of one-loop photon (\\Pi) and neutrino (\\Sigma) two-point functions in a covariant and deformed U(1) gauge-theory on d-dimensional noncommutative spaces, determined by a constant antisymmetric tensor \\theta, and by a parameter-space (\\kappa_f,\\kappa_g), respectively. For the general fermion-photon S_f(\\kappa_f) and photon self-interaction S_g(\\kappa_g) the closed form results reveal two-point functions with all kind of pathological terms: the UV divergence, the quadratic UV/IR mixing terms as well as a logarithmic IR divergent term of the type ln(\\mu^2(\\theta p)^2). In addition, the photon-loop produces new tensor structures satisfying transversality condition by themselves. We show that the photon two-point function in four-dimensional Euclidean spacetime can be reduced to two finite terms by imposing a specific full rank of \\theta and setting deformation parameters (\\kappa_f,\\kappa_g)=(0,3). In this case the neutrino two-point function vanishes. Thus for a specific point (0,3) in the para...
Similarity of solution branches for two-point semilinear problems
Directory of Open Access Journals (Sweden)
Philip Korman
2003-02-01
Full Text Available For semilinear autonomous two-point problems, we show that all Neumann branches and all Dirichlet branches with odd number of interior roots have the same shape. On the other hand, Dirichlet branches with even number of roots may look differently. While this result has been proved previously by Schaaf cite{S}, our approach appears to be simpler.
Correlation function as a measure of the structure
Buryak, O E
1995-01-01
Geometrical model of structure of the universe is examined to obtain analytical expression for the two points nonlinear correlation function. According to the model the objects (galaxies) are concentrated into two types of structure elements - filaments and sheets. We considered the filaments ( similar to galaxy filaments ) simply as straight lines and the sheets ( similar to superclusters of galaxies ) simply as planes. The homogeneously distributed objects are also taken into consideration. The spatial distribution of lines, planes and points is uncorrelated. The nonlinear correlation function depends on four parameters and is similar to the observed and simulated ones for different samples. It describes quite well the correlation of galaxies, clusters of galaxies and dark matter distribution. Possible interpretation of the parameters of nonlinear correlation function is discussed.
Correlation measurements of fission-fragment properties
Oberstedt, S.; Belgya, T.; Billnert, R.; Borcea, R.; Cano-Ott, D.; Göök, A.; Hambsch, F.-J.; Karlsson, J.; Kis, Z.; Martinez, T.; Oberstedt, A.; Szentmiklosi, L.; Takác, K.
2010-10-01
For the development of future nuclear fission applications and for a responsible handling of nuclear waste the a-priori assessment of the fission-fragments' heat production and toxicity is a fundamental necessity. The success of an indispensable modelling of the fission process strongly depends on a good understanding of the particular mechanism of scission, the mass fragmentation and partition of excitation energy. Experimental observables are fission-fragment properties like mass- and energy-distributions, and the prompt neutron as well as γ-ray multiplicities and emission spectra. The latter quantities should preferably be known as a function of fragment mass and excitation energy. Those data are highly demanded as published by the OECD-NEA in its high priority data request list. With the construction of the double (v, E) spectrometer VERDI we aim at measuring pre- and post-neutron masses directly and simultaneously to avoid prompt neutron corrections. From the simultaneous measurement of pre- and post-neutron fission-fragment data the prompt neutron multiplicity may then be inferred fully correlated with fragment mass yield and total kinetic energy. Using an ultra-fast fission event trigger spectral prompt fission γ-ray measurements may be performed. For that purpose recently developed lanthanum-halide detectors, with excellent timing characteristics, were coupled to the VERDI spectrometer allowing for a very good discrimination of fission γ-rays and prompt neutrons due to their different time-of-flight.
Correlation measurements of fission-fragment properties
Directory of Open Access Journals (Sweden)
Oberstedt A.
2010-10-01
Full Text Available For the development of future nuclear fission applications and for a responsible handling of nuclear waste the a-priori assessment of the fission-fragments’ heat production and toxicity is a fundamental necessity. The success of an indispensable modelling of the fission process strongly depends on a good understanding of the particular mechanism of scission, the mass fragmentation and partition of excitation energy. Experimental observables are fission-fragment properties like mass- and energy-distributions, and the prompt neutron as well as γ-ray multiplicities and emission spectra. The latter quantities should preferably be known as a function of fragment mass and excitation energy. Those data are highly demanded as published by the OECD-NEA in its high priority data request list. With the construction of the double (v, E spectrometer VERDI we aim at measuring pre- and post-neutron masses directly and simultaneously to avoid prompt neutron corrections. From the simultaneous measurement of pre- and post-neutron fission-fragment data the prompt neutron multiplicity may then be inferred fully correlated with fragment mass yield and total kinetic energy. Using an ultra-fast fission event trigger spectral prompt fission γ-ray measurements may be performed. For that purpose recently developed lanthanum-halide detectors, with excellent timing characteristics, were coupled to the VERDI spectrometer allowing for a very good discrimination of fission γ-rays and prompt neutrons due to their different time-of-flight.
Measures and applications of quantum correlations
Adesso, Gerardo; Cianciaruso, Marco
2016-01-01
Quantum information theory is built upon the realisation that quantum resources like coherence and entanglement can be exploited for novel or enhanced ways of transmitting and manipulating information, such as quantum cryptography, teleportation, and quantum computing. We now know that there is potentially much more than entanglement behind the power of quantum information processing. There exist more general forms of non-classical correlations, stemming from fundamental principles such as the necessary disturbance induced by a local measurement, or the persistence of quantum coherence in all possible local bases. These signatures can be identified and are resilient in almost all quantum states, and have been linked to the enhanced performance of certain quantum protocols over classical ones in noisy conditions. Their presence represents, among other things, one of the most essential manifestations of quantumness in cooperative systems, from the subatomic to the macroscopic domain. In this work we give an ove...
Total Ossiculoplasty: Advantages of Two-Point Stabilization Technique
Directory of Open Access Journals (Sweden)
Leonard Berenholz
2012-01-01
Full Text Available Objective. Evaluate a porous polyethylene prosthesis with two-point stabilization in total ossiculoplasty. This approach utilizes a lateral as well as a medial graft to stabilize a total ossicular prosthesis (TOP. Study Design. Retrospective cohort review of total ossiculoplasty. Methods. All patients who underwent total ossiculoplasty during the years 2004–2007 were included in the study group. Only five patients (10% had primary surgery whereas 45 (90% underwent revision surgery. Cartilage grafts covering the prosthesis (Sheehy, Xomed laterally were used in all patients with areolar tissue being used for medial stabilization at the stapes footplate. Follow-up examination and audiometrics were performed a mean of 8.1 months following surgery. Results. The percentage of patients closing their ABG to within 10 dB was 44% with 66% closing their ABG to within 20 dB. The mean four-frequency hearing gain was 15.7 dB. The mean postoperative ABG was 15.7 dB. Conclusion. Audiometric results following total ossiculoplasty surgery using two-point stabilization exceeded results from the otologic literature. Proper two-point fixation with areolar tissue and stabilization utilizing cartilage were the keys to achieving a relatively high percentage of success in chronic ear disease in this sample.
Intrinsic alignments of galaxies in the MassiveBlack-II simulation: analysis of two-point statistics
Tenneti, Ananth; Mandelbaum, Rachel; Di Matteo, Tiziana; Feng, Yu; Khandai, Nishikanta
2014-01-01
The intrinsic alignment of galaxies with the large-scale density field is an important astrophysical contaminant in upcoming weak lensing surveys whilst offering insights into galaxy formation and evolution. We present detailed measurements of the galaxy intrinsic alignments and associated ellipticity-direction (ED) and projected shape ($w_{g+}$) correlation functions for galaxies in the cosmological hydrodynamic MassiveBlack-II (MB-II) simulation. We carefully assess the effects on galaxy shapes, misalignments and two-point statistics of iterative weighted (by mass, luminosity, and color) definitions of the (reduced and unreduced) inertia tensor. We find that iterative procedures must be adopted for a reliable measurement of reduced tensor but that luminosity versus mass weighting has only negligible effects. Blue galaxies exhibit stronger misalignments and suppressed $w_{g+}$ amplitude. Both ED and $w_{g+}$ correlations increase in amplitude with subhalo mass (in the range of $10^{10} - 6.0\\times 10^{14}h^{...
Measurement and correlates of physicians' lifelong learning.
Hojat, Mohammadreza; Veloski, J Jon; Gonnella, Joseph S
2009-08-01
To examine the psychometric properties and correlates of an instrument to measure physicians' orientation toward lifelong learning with attention to differences between full-time and academic clinicians. The authors mailed a survey in 2006 to a national sample of 5,349 alumni of Jefferson Medical College who graduated between 1975 and 2000; 3,195 (60%) responded. The respondents were classified as full-time clinicians (n = 1,127) and academic clinicians (n = 1,612). The other 456 respondents were involved in administration or research. The revised Jefferson Scale of Physician Lifelong Learning (JeffSPLL) was included in the survey. Factor analysis, regression analysis, and analysis of variance were used to examine the construct- and criterion-related validities of the scale. Factor analysis of the JeffSPLL items resulted in three factors designated as "learning beliefs and motivation," "attention to learning opportunities," and "skills in seeking information," which supported its construct validity. Alpha reliability coefficients were 0.85 and 0.86, and test-retest reliability coefficients were 0.72 and 0.77 for full-time clinicians and academic clinicians, respectively. For full-time clinicians and academic clinicians, scores on the JeffSPLL were significantly (P satisfaction, and commitment to lifelong learning, which supported the criterion-related validity of the scale. The findings indicate that the JeffSPLL is a psychometrically sound instrument that measures physicians' orientation toward lifelong learning among full-time clinicians and academic clinicians. The instrument can be used to monitor educational programs, assess educational outcomes, and examine group differences.
Problem with two-point conditions for parabolic equation of second order on time
Directory of Open Access Journals (Sweden)
M. M. Symotyuk
2014-12-01
Full Text Available The correctness of a problem with two-point conditions ontime-variable and of Dirichlet-type conditions on spatialcoordinates for the linear parabolic equations with variablecoefficients are established. The metric theorem on estimationsfrom below of small denominators of the problem (the notions of Hausdorff measure is proved.
Theory of resistor networks: the two-point resistance
Energy Technology Data Exchange (ETDEWEB)
Wu, F Y [Department of Physics, Northeastern University Boston, MA 02115 (United States)
2004-07-02
The resistance between two arbitrary nodes in a resistor network is obtained in terms of the eigenvalues and eigenfunctions of the Laplacian matrix associated with the network. Explicit formulae for two-point resistances are deduced for regular lattices in one, two and three dimensions under various boundary conditions including that of a Moebius strip and a Klein bottle. The emphasis is on lattices of finite sizes. We also deduce summation and product identities which can be used to analyse large-size expansions in two and higher dimensions.
Measuring and modelling correlations in multiplex networks
Nicosia, Vincenzo
2014-01-01
In many complex systems the interactions among the elementary components can be of qualitatively different nature. Such systems are therefore naturally described and represented in terms of multiplex or multi-layer networks, i.e. networks where each layer stands for a different type of interaction between the same set of nodes. There is today a growing interest in understanding when and why a description in terms of a multiplex network is necessary and more informative than a single-layer projection. Here, we contribute to this debate by presenting a comprehensive study of correlations in multiplex networks. Correlations in node properties, especially degree-degree correlations, have been thoroughly studied in single-layer networks. Here we extend this idea to investigate and characterize correlations between the different layers of a multiplex network. These correlations are intrinsically multiplex, and we first study them empirically by constructing and analyzing various multiplex networks from the real-wor...
Beyond Kaiser bias: mildly non-linear two-point statistics of densities in distant spheres
Uhlemann, C.; Codis, S.; Kim, J.; Pichon, C.; Bernardeau, F.; Pogosyan, D.; Park, C.; L'Huillier, B.
2017-04-01
We present simple parameter-free analytic bias functions for the two-point correlation of densities in spheres at large separation. These bias functions generalize the so-called Kaiser bias to the mildly non-linear regime for arbitrary density contrasts and grow as b(ρ) - b(1) ∝ (1 - ρ-13/21)ρ1 + n/3 with b(1) = -4/21 - n/3 for a power-law initial spectrum with index n. We carry out the derivation in the context of large-deviation statistics while relying on the spherical collapse model. We use a logarithmic transformation that provides a saddle-point approximation that is valid for the whole range of densities and show its accuracy against the 30 Gpc cube state-of-the-art Horizon Run 4 simulation. Special configurations of two concentric spheres that allow us to identify peaks are employed to obtain the conditional bias and a proxy for the BBKS extremum correlation functions. These analytic bias functions should be used jointly with extended perturbation theory to predict two-point clustering statistics as they capture the non-linear regime of structure formation at the per cent level down to scales of about 10 Mpc h-1 at redshift 0. Conversely, the joint statistics also provide us with optimal dark matter two-point correlation estimates that can be applied either universally to all spheres or to a restricted set of biased (over- or underdense) pairs. Based on a simple fiducial survey, we show that the variance of this estimator is reduced by five times relative to the traditional sample estimator for the two-point function. Extracting more information from correlations of different types of objects should prove essential in the context of upcoming surveys like Euclid, DESI and WFIRST.
Correlations between outcomes of random measurements
Tran, Minh Cong; Dakić, Borivoje; Laskowski, Wiesław; Paterek, Tomasz
2016-10-01
We recently showed that multipartite correlations between outcomes of random observables detect quantum entanglement in all pure and some mixed states. In this followup article we further develop this approach, derive a maximal amount of such correlations, and show that they are not monotonous under local operations and classical communication. Nevertheless, we demonstrate their usefulness in entanglement detection with a single random observable per party. Finally we study convex-roof extension of the correlations and provide a closed-form necessary and sufficient condition for entanglement in rank-2 mixed states and a witness in general.
Two-point functions in (loop) quantum cosmology
Energy Technology Data Exchange (ETDEWEB)
Calcagni, Gianluca; Gielen, Steffen; Oriti, Daniele, E-mail: calcagni@aei.mpg.de, E-mail: gielen@aei.mpg.de, E-mail: doriti@aei.mpg.de [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Muehlenberg 1, D-14476 Golm (Germany)
2011-06-21
The path-integral formulation of quantum cosmology with a massless scalar field as a sum-over-histories of volume transitions is discussed, with particular but non-exclusive reference to loop quantum cosmology. Exploiting the analogy with the relativistic particle, we give a complete overview of the possible two-point functions, pointing out the choices involved in their definitions, deriving their vertex expansions and the composition laws they satisfy. We clarify the origin and relations of different quantities previously defined in the literature, in particular the tie between definitions using a group averaging procedure and those in a deparametrized framework. Finally, we draw some conclusions about the physics of a single quantum universe (where there exist superselection rules on positive- and negative-frequency sectors and different choices of inner product are physically equivalent) and multiverse field theories where the role of these sectors and the inner product are reinterpreted.
Two-point functions in (loop) quantum cosmology
Energy Technology Data Exchange (ETDEWEB)
Calcagni, Gianluca; Oriti, Daniele [Max-Planck-Institute for Gravitational Physics (Albert Einstein Institute), Am Muehlenberg 1, D-14476 Golm (Germany); Gielen, Steffen [Max-Planck-Institute for Gravitational Physics (Albert Einstein Institute), Am Muehlenberg 1, D-14476 Golm (Germany); DAMTP, Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)
2011-07-01
We discuss the path-integral formulation of quantum cosmology with a massless scalar field as a sum-over-histories of volume transitions, with particular but non-exclusive reference to loop quantum cosmology (LQC). Exploiting the analogy with the relativistic particle, we give a complete overview of the possible two-point functions, pointing out the choices involved in their definitions, deriving their vertex expansions and the composition laws they satisfy. We clarify the origin and relations of different quantities previously defined in the literature, in particular the tie between definitions using a group averaging procedure and those in a deparametrized framework. Finally, we draw some conclusions about the physics of a single quantum universe (where there exist superselection rules on positive- and negative-frequency sectors and different choices of inner product are physically equivalent) and multiverse field theories where the role of these sectors and the inner product are reinterpreted.
Multi-scale crack closure measurements with digital image correlation on Haynes 230
Directory of Open Access Journals (Sweden)
Stefano Beretta
2015-07-01
Full Text Available An experimental campaign was developed to study fatigue crack growth in Haynes 230, a Ni-based superalloy. The effects of crack closure were investigated with digital image correlation, by applying two different approaches. Initially, full field regression algorithms were applied to extract the effective stress intensity factor ranges from the singular displacement field measured at crack tips. Local closure measurements were then performed by considering crack flanks relative displacements. Two points virtual extensometers were applied in this phase. Experimental results were then compared to the reference da/dN –ΔKeff curve: it was found that the correct estimation of crack opening levels shifts all the experimental points on the reference curve, showing that DIC can be successfully applied to measure crack closure effects.
Meta-Analysis of Correlations Among Usability Measures
DEFF Research Database (Denmark)
Hornbæk, Kasper Anders Søren; Effie Lai Chong, Law
2007-01-01
are generally low: effectiveness measures (e.g., errors) and efficiency measures (e.g., time) has a correlation of .247 ± .059 (Pearson's product-moment correlation with 95% confidence interval), efficiency and satisfaction (e.g., preference) one of .196 ± .064, and effectiveness and satisfaction one of .164......Understanding the relation between usability measures seems crucial to deepen our conception of usability and to select the right measures for usability studies. We present a meta-analysis of correlations among usability measures calculated from the raw data of 73 studies. Correlations...... ± .062. Changes in task complexity do not influence these correlations, but use of more complex measures attenuates them. Standard questionnaires for measuring satisfaction appear more reliable than homegrown ones. Measures of users' perceptions of phenomena are generally not correlated with objective...
Two-point discrimination of the upper extremities of healthy Koreans in their 20's.
Koo, Ja-Pung; Kim, Soon-Hee; An, Ho-Jung; Moon, Ok-Gon; Choi, Jung-Hyun; Yun, Young-Dae; Park, Joo-Hyun; Min, Kyoung-Ok
2016-03-01
[Purpose] The present study attempted to measure two-point discrimination in the upper extremities of healthy Koreans in their 20's. [Subjects and Methods] Using a three-point esthesiometer, we conducted an experiment with a group of 256 college students (128 male and 128 female), attending N University in Chonan, Republic of Korea. [Results] Females showed two-point discrimination at a shorter distance than males at the following points: (i) 5 cm above the elbow joint, the middle part, and 5 cm below the shoulder joint of the anterior upper arm; (ii) 5 cm above the elbow joint and 5 cm below the shoulder joint of the posterior upper arm; (iii) 5 cm above the front of the wrist joint of the forearm; 5 cm below the elbow joint, the palmar part of the distal interphalangeal joint of the thumb, the dorsal part of the distal interphalangeal joint of the middle and little fingers. It was also found that females showed greater two-point discrimination than males in distal regions rather than proximal regions. [Conclusion] The findings of this study will help establish normal values for two-point discrimination of upper extremities of young Koreans in their 20's.
Filtering with perfectly correlated measurement noise.
Reasenberg, R.
1972-01-01
Examination of (radar) Doppler data which are formed by mi1ing the returning microwave signal with a replica of the transmitted signal, counting the cycles of the beat, and sampling the counter at evenly spaced intervals t sub i. It is shown that the amount of information which can be extracted from a set of data may be larger if the associated noise is perfectly correlated than if it is white, and that the use of the white noise assumption in the filter may result in the loss of some of this information.
A multiscale two-point flux-approximation method
Møyner, Olav; Lie, Knut-Andreas
2014-10-01
A large number of multiscale finite-volume methods have been developed over the past decade to compute conservative approximations to multiphase flow problems in heterogeneous porous media. In particular, several iterative and algebraic multiscale frameworks that seek to reduce the fine-scale residual towards machine precision have been presented. Common for all such methods is that they rely on a compatible primal-dual coarse partition, which makes it challenging to extend them to stratigraphic and unstructured grids. Herein, we propose a general idea for how one can formulate multiscale finite-volume methods using only a primal coarse partition. To this end, we use two key ingredients that are computed numerically: (i) elementary functions that correspond to flow solutions used in transmissibility upscaling, and (ii) partition-of-unity functions used to combine elementary functions into basis functions. We exemplify the idea by deriving a multiscale two-point flux-approximation (MsTPFA) method, which is robust with regards to strong heterogeneities in the permeability field and can easily handle general grids with unstructured fine- and coarse-scale connections. The method can easily be adapted to arbitrary levels of coarsening, and can be used both as a standalone solver and as a preconditioner. Several numerical experiments are presented to demonstrate that the MsTPFA method can be used to solve elliptic pressure problems on a wide variety of geological models in a robust and efficient manner.
Comparison of Optimization and Two-point Methods in Estimation of Soil Water Retention Curve
Ghanbarian-Alavijeh, B.; Liaghat, A. M.; Huang, G.
2009-04-01
Soil water retention curve (SWRC) is one of the soil hydraulic properties in which its direct measurement is time consuming and expensive. Since, its measurement is unavoidable in study of environmental sciences i.e. investigation of unsaturated hydraulic conductivity and solute transport, in this study the attempt is to predict soil water retention curve from two measured points. By using Cresswell and Paydar (1996) method (two-point method) and an optimization method developed in this study on the basis of two points of SWRC, parameters of Tyler and Wheatcraft (1990) model (fractal dimension and air entry value) were estimated and then water content at different matric potentials were estimated and compared with their measured values (n=180). For each method, we used both 3 and 1500 kPa (case 1) and 33 and 1500 kPa (case 2) as two points of SWRC. The calculated RMSE values showed that in the Creswell and Paydar (1996) method, there exists no significant difference between case 1 and case 2. However, the calculated RMSE value in case 2 (2.35) was slightly less than case 1 (2.37). The results also showed that the developed optimization method in this study had significantly less RMSE values for cases 1 (1.63) and 2 (1.33) rather than Cresswell and Paydar (1996) method.
A NEW METHOD TO CORRECT FOR FIBER COLLISIONS IN GALAXY TWO-POINT STATISTICS
Energy Technology Data Exchange (ETDEWEB)
Guo Hong; Zehavi, Idit [Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106 (United States); Zheng Zheng [Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, UT 84112 (United States)
2012-09-10
In fiber-fed galaxy redshift surveys, the finite size of the fiber plugs prevents two fibers from being placed too close to one another, limiting the ability to study galaxy clustering on all scales. We present a new method for correcting such fiber collision effects in galaxy clustering statistics based on spectroscopic observations. The target galaxy sample is divided into two distinct populations according to the targeting algorithm of fiber placement, one free of fiber collisions and the other consisting of collided galaxies. The clustering statistics are a combination of the contributions from these two populations. Our method makes use of observations in tile overlap regions to measure the contributions from the collided population, and to therefore recover the full clustering statistics. The method is rooted in solid theoretical ground and is tested extensively on mock galaxy catalogs. We demonstrate that our method can well recover the projected and the full three-dimensional (3D) redshift-space two-point correlation functions (2PCFs) on scales both below and above the fiber collision scale, superior to the commonly used nearest neighbor and angular correction methods. We discuss potential systematic effects in our method. The statistical correction accuracy of our method is only limited by sample variance, which scales down with (the square root of) the volume probed. For a sample similar to the final SDSS-III BOSS galaxy sample, the statistical correction error is expected to be at the level of 1% on scales {approx}0.1-30 h {sup -1} Mpc for the 2PCFs. The systematic error only occurs on small scales, caused by imperfect correction of collision multiplets, and its magnitude is expected to be smaller than 5%. Our correction method, which can be generalized to other clustering statistics as well, enables more accurate measurements of full 3D galaxy clustering on all scales with galaxy redshift surveys.
d + Au hadron correlation measurements at PHENIX
Energy Technology Data Exchange (ETDEWEB)
Sickles, Anne M., E-mail: anne@bnl.gov
2014-06-15
In these proceedings, we discuss recent results from d + Au collisions in PHENIX ridge related measurements and their possible hydrodynamic origin. We present the v{sub 2} at midrapidity and measurements of the pseudorapidity dependence of the ridge, distinguishing between the d-going and Au-going directions. We investigate the possible geometrical origin by comparing v{sub 2} in d + Au to that in p + Pb, Au + Au and Pb + Pb collisions. Future plans to clarify the role of geometry in small collision systems at RHIC are discussed.
Correlated measurement error hampers association network inference
Kaduk, M.; Hoefsloot, H.C.J.; Vis, D.J.; Reijmers, T.; van der Greef, J.; Smilde, A.K.; Hendriks, M.M.W.B.
2014-01-01
Modern chromatography-based metabolomics measurements generate large amounts of data in the form of abundances of metabolites. An increasingly popular way of representing and analyzing such data is by means of association networks. Ideally, such a network can be interpreted in terms of the underlyin
Reflexivity in Teams: A Measure and Correlates
M.C. Schippers (Michaéla); D.N. den Hartog (Deanne); P.L. Koopman (Paul)
2005-01-01
textabstractReflexivity -the extent to which teams reflect upon and modify their functioning- has been identified as a possible key factor in the effectiveness of work teams. The aim of the present study was to develop a questionnaire to measure (aspects of) reflexivity, with a focus on team reflect
Bin-bin correlation measurement by bunching-parameter method
Energy Technology Data Exchange (ETDEWEB)
Chekanov, S.V.; Kittel, W. [High Energy Physics Inst. Nijmegen, Univ. of Nijmegen/NIKHEF, Nijmegen (Netherlands); Kuvshinov, V.I. [Inst. of Physics, Academy of Sciences of Belarus, Minsk (Belgium)
1996-08-01
A new method for the experimental study of bin-bin correlations is proposed. It is shown that this method is able to reveal important additional information on bin-bin correlations, beyond that of factorial-correlator measurements. (author) 15 refs, 1 fig
Quantum discord and other measures of quantum correlation
Modi, Kavan; Cable, Hugo; Paterek, Tomasz; Vedral, Vlatko
2011-01-01
One of the best signatures of nonclassicality in a quantum system is the existence of correlations that have no classical counterpart. Different methods for quantifying the quantum and classical parts of the correlations are amongst the most actively-studied topics of quantum information theory in the past decade. Entanglement is the most prominent of these correlations, but in many cases unentangled states exhibit nonclassical behavior. Thus distinguishing quantum correlation other than entanglement provides a better division between the quantum and classical worlds, especially when considering mixed states. Here we review different notions of classical and quantum correlations quantified by quantum discord and other related measures. In the first half we review the mathematical properties of the measures of quantum correlation, relate them to each other, and discuss the classical-quantum division that is common among them. In the second half, we show that the measures quantum correlation identify and quanti...
Unification of quantum and classical correlations and quantumness measures
Modi, Kavan
2011-01-01
We give a pedagogical introduction to quantum discord. We the discuss the problem of separation of total correlations in a given quantum state into entanglement, dissonance, and classical correlations using the concept of relative entropy as a distance measure of correlations. This allows us to put all correlations on an equal footing. Entanglement and dissonance, whose definition is introduced here, jointly belong to what is known as quantum discord. Our methods are completely applicable for multipartite systems of arbitrary dimensions. We finally show, using relative entropy, how different notions of quantum correlations are related to each other. This gives a single theory that incorporates all correlations, quantum, classical, etc.
Overview of recent azimuthal correlation measurements from ALICE
INSPIRE-00290856
2016-01-01
Azimuthal correlations are a powerful tool to probe the properties and the evolution of the collision system. In this proceedings, we will review the recent azimuthal correlation measurements from ALICE at the LHC. The comparison to other experimental measurements and various theoretical calculations will be discussed as well.
Beyond Kaiser bias: mildly non-linear two-point statistics of densities in distant spheres
Uhlemann, C; Kim, J; Pichon, C; Bernardeau, F; Pogosyan, D; Park, C; L'Huillier, B
2016-01-01
Simple parameter-free analytic bias functions for the two-point correlation of densities in spheres at large separation are presented. These bias functions generalize the so-called Kaiser bias to the mildly non-linear regime for arbitrary density contrasts. The derivation is carried out in the context of large deviation statistics while relying on the spherical collapse model. A logarithmic transformation provides a saddle approximation which is valid for the whole range of densities and shown to be accurate against the 30 Gpc cube state-of-the-art Horizon Run 4 simulation. Special configurations of two concentric spheres that allow to identify peaks are employed to obtain the conditional bias and a proxy to BBKS extrema correlation functions. These analytic bias functions should be used jointly with extended perturbation theory to predict two-point clustering statistics as they capture the non-linear regime of structure formation at the percent level down to scales of about 10 Mpc/h at redshift 0. Conversely...
THE CHERNOBYL ACCIDENT AND HEALTH (TWO POINTS OF VIEW
Directory of Open Access Journals (Sweden)
V. M. Shubik
2011-01-01
Full Text Available The article presents two alternative points of view on the relationship of health malfunctions after the Chernobyl accident with radiation effect or with the factors of non-radiation nature (social, stress, nutrition peculiarities, etc.. An analysis of literature data and results of author’s own research of radiosensitive indicators of immunity condition, having essential value for the immediate and long term consequences of radiation effect was done. Possible correlation between health malfunctions of the population living in the regions, contaminated by the radionuclides, and combined effect of radiation and factors of non-radiation nature is shown.
Measurement of the dipole in the cross-correlation function of galaxies
Gaztanaga, Enrique; Hui, Lam
2017-01-01
It is usually assumed that in the linear regime the two-point correlation function of galaxies contains only a monopole, quadrupole and hexadecapole. Looking at cross-correlations between different populations of galaxies, this turns out not to be the case. In particular, the cross-correlations between a bright and a faint population of galaxies contain also a dipole. In this paper we present the first attempt to measure this dipole. We discuss the four types of effects that contribute to the dipole: relativistic distortions, evolution effect, wide-angle effect and large-angle effect. We show that the first three contributions are intrinsic anti-symmetric contributions that do not depend on the choice of angle used to measure the dipole. On the other hand the large-angle effect appears only if the angle chosen to extract the dipole breaks the symmetry of the problem. We show that the relativistic distortions, the evolution effect and the wide-angle effect are too small to be detected in the LOWz and CMASS sam...
Relating quantum coherence and correlations with entropy-based measures.
Wang, Xiao-Li; Yue, Qiu-Ling; Yu, Chao-Hua; Gao, Fei; Qin, Su-Juan
2017-09-21
Quantum coherence and quantum correlations are important quantum resources for quantum computation and quantum information. In this paper, using entropy-based measures, we investigate the relationships between quantum correlated coherence, which is the coherence between subsystems, and two main kinds of quantum correlations as defined by quantum discord as well as quantum entanglement. In particular, we show that quantum discord and quantum entanglement can be well characterized by quantum correlated coherence. Moreover, we prove that the entanglement measure formulated by quantum correlated coherence is lower and upper bounded by the relative entropy of entanglement and the entanglement of formation, respectively, and equal to the relative entropy of entanglement for all the maximally correlated states.
Multifunctional optical correlator for picosecond ultraviolet laser pulse measurement.
Rakhman, Abdurahim; Wang, Yang; Garcia, Frances; Long, Cary; Huang, Chunning; Takeda, Yasuhiro; Liu, Yun
2014-11-01
A compact multifunctional optical correlator system for pulse width measurement of ultrashort ultraviolet (UV) pulses has been designed and experimentally demonstrated. Both autocorrelation and cross-correlation functions are measured using a single nonlinear crystal, and the switching between two measurements requires no adjustment of phase matching and detector. The system can measure UV pulse widths from sub-picoseconds to 100 ps, and it involves no auxiliary pulse in the measurement. The measurement results on a burst-mode picosecond UV laser show a high-quality performance on speed, accuracy, resolution, and dynamic range. The proposed correlator can be applied to measure any ultrashort UV pulses produced through sum-frequency generation or second-harmonic generation.
Asymptotic behaviour of two-point functions in multi-species models
Directory of Open Access Journals (Sweden)
Karol K. Kozlowski
2016-05-01
Full Text Available We extract the long-distance asymptotic behaviour of two-point correlation functions in massless quantum integrable models containing multi-species excitations. For such a purpose, we extend to these models the method of a large-distance regime re-summation of the form factor expansion of correlation functions. The key feature of our analysis is a technical hypothesis on the large-volume behaviour of the form factors of local operators in such models. We check the validity of this hypothesis on the example of the SU(3-invariant XXX magnet by means of the determinant representations for the form factors of local operators in this model. Our approach confirms the structure of the critical exponents obtained previously for numerous models solvable by the nested Bethe Ansatz.
Asymptotic behaviour of two-point functions in multi-species models
Kozlowski, Karol K.; Ragoucy, Eric
2016-05-01
We extract the long-distance asymptotic behaviour of two-point correlation functions in massless quantum integrable models containing multi-species excitations. For such a purpose, we extend to these models the method of a large-distance regime re-summation of the form factor expansion of correlation functions. The key feature of our analysis is a technical hypothesis on the large-volume behaviour of the form factors of local operators in such models. We check the validity of this hypothesis on the example of the SU (3)-invariant XXX magnet by means of the determinant representations for the form factors of local operators in this model. Our approach confirms the structure of the critical exponents obtained previously for numerous models solvable by the nested Bethe Ansatz.
Expansion schemes for gravitational clustering: computing two-point and three-point functions
Valageas, P
2007-01-01
We describe various expansion schemes that can be used to study gravitational clustering. Obtained from the equations of motion or their path-integral formulation, they provide several perturbative expansions that are organized in different fashion or involve different partial resummations. We focus on the two-point and three-point correlation functions, but these methods also apply to all higher-order correlation and response functions. We present the general formalism, which holds for the gravitational dynamics as well as for similar models, such as the Zeldovich dynamics, that obey similar hydrodynamical equations of motion with a quadratic nonlinearity. We give our explicit analytical results up to one-loop order for the simpler Zeldovich dynamics. For the gravitational dynamics, we compare our one-loop numerical results with numerical simulations. We check that the standard perturbation theory is recovered from the path integral by expanding over Feynman's diagrams. However, the latter expansion is organ...
Enhancing robustness of multiparty quantum correlations using weak measurement
Energy Technology Data Exchange (ETDEWEB)
Singh, Uttam, E-mail: uttamsingh@hri.res.in [Quantum Information and Computation Group, Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019 (India); Mishra, Utkarsh, E-mail: utkarsh@hri.res.in [Quantum Information and Computation Group, Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019 (India); Dhar, Himadri Shekhar, E-mail: dhar.himadri@gmail.com [School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067 (India)
2014-11-15
Multipartite quantum correlations are important resources for the development of quantum information and computation protocols. However, the resourcefulness of multipartite quantum correlations in practical settings is limited by its fragility under decoherence due to environmental interactions. Though there exist protocols to protect bipartite entanglement under decoherence, the implementation of such protocols for multipartite quantum correlations has not been sufficiently explored. Here, we study the effect of local amplitude damping channel on the generalized Greenberger–Horne–Zeilinger state, and use a protocol of optimal reversal quantum weak measurement to protect the multipartite quantum correlations. We observe that the weak measurement reversal protocol enhances the robustness of multipartite quantum correlations. Further it increases the critical damping value that corresponds to entanglement sudden death. To emphasize the efficacy of the technique in protection of multipartite quantum correlation, we investigate two proximately related quantum communication tasks, namely, quantum teleportation in a one sender, many receivers setting and multiparty quantum information splitting, through a local amplitude damping channel. We observe an increase in the average fidelity of both the quantum communication tasks under the weak measurement reversal protocol. The method may prove beneficial, for combating external interactions, in other quantum information tasks using multipartite resources. - Highlights: • Extension of weak measurement reversal scheme to protect multiparty quantum correlations. • Protection of multiparty quantum correlation under local amplitude damping noise. • Enhanced fidelity of quantum teleportation in one sender and many receivers setting. • Enhanced fidelity of quantum information splitting protocol.
A Review of the Correlates and Measurements of Career Indecision.
Sepich, Robert T.
1987-01-01
Reviews the literature to enhance practitioner understanding of career indecision. Attempts to answer two questions: (1) What are correlates of career indecision? and (2) How is it measured? Summarizes findings; suggests research areas. (CH)
Analysing H(z) data using two-point diagnostics
Leaf, Kyle; Melia, Fulvio
2017-09-01
Measurements of the Hubble constant H(z) are increasingly being used to test the expansion rate predicted by various cosmological models. But the recent application of 2-point diagnostics, such as Om(z_i,z_j) and Omh^2(z_i,z_j), has produced considerable tension between LCDM's predictions and several observations, with other models faring even worse. Part of this problem is attributable to the continued mixing of truly model-independent measurements using the cosmic-chronomter approach, and model-dependent data extracted from BAOs. In this paper, we advance the use of 2-point diagnostics beyond their current status, and introduce new variations, which we call Delta h(z_i,z_j), that are more useful for model comparisons. But we restrict our analysis exclusively to cosmic-chronometer data, which are truly model independent. Even for these measurements, however, we confirm the conclusions drawn by earlier workers that the data have strongly non-Gaussian uncertainties, requiring the use of both "median" and "mean" statistical approaches. Our results reveal that previous analyses using 2-point diagnostics greatly underestimated the errors, thereby misinterpreting the level of tension between theoretical predictions and H(z) data. Instead, we demonstrate that as of today, only Einstein-de Sitter is ruled out by the 2-point diagnostics at a level of significance exceeding ~ 3 sigma. The R_h=ct universe is slightly favoured over the remaining models, including LCDM and Chevalier-Polarski-Linder, though all of them (other than Einstein-de Sitter) are consistent to within 1 sigma with the measured mean of the Delta h(z_i,z_j) diagnostics.
Improved position measurement of nanoelectromechanical systems using cross correlations
Doiron, C. B.; Trauzettel, B.; Bruder, C.
2007-11-01
We consider position measurements using the cross-correlated output of two tunnel-junction position detectors. Using a fully quantum treatment, we calculate the equation of motion for the density matrix of the coupled detector detector mechanical-oscillator system. After discussing the presence of a bound on the peak-to-background ratio in a position measurement using a single detector, we show how one can use detector cross correlations to overcome this bound. We analyze two different possible experimental realizations of the cross-correlation measurement and show that in both cases, the maximum cross-correlated output is obtained when using twin detectors and applying equal bias to each tunnel junction. Furthermore, we show how the double-detector setup can be exploited to drastically reduce the added displacement noise of the oscillator.
Kleinmann, Matthias; Cabello, Adán
2016-10-07
We show that, for any n, there are m-outcome quantum correlations, with m>n, which are stronger than any nonsignaling correlation produced from selecting among n-outcome measurements. As a consequence, for any n, there are m-outcome quantum measurements that cannot be constructed by selecting locally from the set of n-outcome measurements. This is a property of the set of measurements in quantum theory that is not mandatory for general probabilistic theories. We also show that this prediction can be tested through high-precision Bell-type experiments and identify past experiments providing evidence that some of these strong correlations exist in nature. Finally, we provide a modified version of quantum theory restricted to having at most n-outcome quantum measurements.
Measurements of the vertical correlation in turbulence under broken waves
DEFF Research Database (Denmark)
Pedersen, Claus; Deigaard, Rolf; Sutherland, James
1998-01-01
Turbulence measurements have been carried out in the surf zone of a wave flume. The purpose of the measurements is to determine the length scale of the turbulence generated by the wave breaking. The length scale of the turbulence is estimated on basis of the correlation between simultaneous measu...
Internalized Heterosexism: Measurement, Psychosocial Correlates, and Research Directions
Szymanski, Dawn M.; Kashubeck-West, Susan; Meyer, Jill
2008-01-01
This article provides an integrated critical review of the literature on internalized heterosexism/internalized homophobia (IH), its measurement, and its psychosocial correlates. It describes the psychometric properties of six published measures used to operationalize the construct of IH. It also critically reviews empirical studies on correlates…
Statistical measures of Planck scale signal correlations in interferometers
Energy Technology Data Exchange (ETDEWEB)
Hogan, Craig J. [Univ. of Chicago, Chicago, IL (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Kwon, Ohkyung [Univ. of Chicago, Chicago, IL (United States)
2015-06-22
A model-independent statistical framework is presented to interpret data from systems where the mean time derivative of positional cross correlation between world lines, a measure of spreading in a quantum geometrical wave function, is measured with a precision smaller than the Planck time. The framework provides a general way to constrain possible departures from perfect independence of classical world lines, associated with Planck scale bounds on positional information. A parametrized candidate set of possible correlation functions is shown to be consistent with the known causal structure of the classical geometry measured by an apparatus, and the holographic scaling of information suggested by gravity. Frequency-domain power spectra are derived that can be compared with interferometer data. As a result, simple projections of sensitivity for specific experimental set-ups suggests that measurements will directly yield constraints on a universal time derivative of the correlation function, and thereby confirm or rule out a class of Planck scale departures from classical geometry.
Quantization of fluctuations in DSR: the two-point function and beyond
Gubitosi, Giulia; Magueijo, Joao
2015-01-01
We show that the two-point function of a quantum field theory with de Sitter momentum space (herein called DSR) can be expressed as the product of a standard delta function and an energy-dependent factor. This is a highly non-trivial technical result in any theory without a preferred frame. Applied to models exhibiting running of the dimensionality of space, this result is essential in proving that vacuum fluctuations are generally scale-invariant at high energies whenever there is running to two dimensions. This is equally true for theories with and without a preferred frame, with differences arising only as we consider higher order correlators. Specifically, the three-point function of DSR has a unique structure of "open triangles", as shown here.
Gamma-Gamma Angular Correlation Measurements With GRIFFIN
Maclean, Andrew; Griffin Collaboration
2016-09-01
The goal of this work was to explore the sensitivity of the Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei (GRIFFIN) 16 clover-detector γ-ray spectrometer at TRIUMF-ISAC to such γ - γ angular correlations. The methodology was established using both experimental measurements and Geant4 simulations that were used to create angular correlation templates for the GRIFFIN geometry. Direct comparisons were made between experimental data sets and the simulated angular correlation templates. A first in-beam test of the γ - γ angular correlation measurements with GRIFFIN was performed with a radioactive beam of 66Ga. Mixing ratios of δ = - 2 . 1(2) and δ = - 0 . 08(3) were measured for the 2+ ->2+ ->0+ 833-1039 keV and 1+ ->2+ ->0+ 2752-1039 keV cascades in the daughter nucleus 66Zn. These results are in good agreement with pervious literature values and the mixing ratio for the 833-1039 keV cascade has a higher precision. Also, the sensitivity to the 1333-1039 keV cascade, with its pronounced 0+ ->2+ ->0+ angular correlation, was measured.A test measurement of the superallowed Fermi β emitter 62Ga will also be discussed. Canada Foundation of Innovation, Natural Sciences and Engineering Research Council of Canada, National Research Council of Canada and Canadian Research Chairs Program.
Measurements of Bose-Einstein correlations with the ATLAS detector
Sykora, Ivan; The ATLAS collaboration
2015-01-01
The Bose-Einstein correlations provide a unique opportunity for detailed understanding of space-time characteristics of the hadronization region, for determining the size and shape of the source from which particles are emitted and for interpreting quark confinement effects. The correlations lead to enhancement in production of identical bosons that are close in phase space. The ATLAS collaboration has performed a measurement of Bose-Einstein correlations of pairs of charged particles with transverse momentum greater than 100 MeV in p-p collisions at 900 GeV and 7 TeV. Bose-Einstein correlation parameters are investigated up to very high charged-particle multiplicities. The dependence of the Bose-Einstein correlation parameters on the average transverse momentum per pair is also investigated.
First Measurements of Pion Correlations by the PHENIX Experiment
Energy Technology Data Exchange (ETDEWEB)
Johnson, S C
2001-04-11
First identical-pion correlations measured at RHIC energies by PHENIX are presented. Two analyses with separate detectors, systematics, and statistics provide consistent results. The resulting HBT radii are moderately larger than those measured at lower energies. The k{sub t} dependence of the Bertsch-Pratt HBT radii is also similar to previous measures and is consistent with the conjecture of an expanding source.
Application of Laser Correlation Spectroscopy for Measuring Virus Size.
Nikiforov, V N; Vinogradov, S E; Ivanov, A V; Efremova, E V; Kalnina, L B; Bychenko, A B; Tentsov, Yu Yu; Manykin, A A
2016-05-01
Dynamic light scattering method or laser correlation spectroscopy was applied to evaluation of the size of viruses. We measured correlation functions of the light scattered by human immunodeficiency viruses (HIV) and hepatitis A viruses (HAV) and found that size of HIV-1 (subtype A and B) and HAV virions were 104 nm and 28 nm, respectively. Comparison of these findings with electron microscopy data for fixed samples of the same viruses showed good agreement of the results.
Measurement of pd , pt , and dd correlation functions
Energy Technology Data Exchange (ETDEWEB)
Vlasov, A.V.; Degtyarenko, P.V.; Doroshkevich, E.A.; Kosov, M.V.; Leksin, G.A.; Stavinskii, A.V.; Khasanov, F.M.; Shvartsman, B.B. (Institute of Theoretical and Experimental Physics, State Commission on Use of Atomic Energy (SU))
1989-09-01
Binary correlation functions have been measured for cumulative baryons emitted from nuclei of C, Ti, and Pb bombarded by 7.5-GeV/{ital c} protons. Secondary particles (protons, deuterons, and tritium nuclei) were detected at polar angles close to 90{degree}. It was found that for a fixed value of the product of the momenta of two particles the correlation function does not depend on what kind of particles make up the pair. The data are consistent with the idea that the sizes of the sources determined from correlations of different particles are the same.
Compressed Sensing with Linear Correlation Between Signal and Measurement Noise
DEFF Research Database (Denmark)
Arildsen, Thomas; Larsen, Torben
2014-01-01
Existing convex relaxation-based approaches to reconstruction in compressed sensing assume that noise in the measurements is independent of the signal of interest. We consider the case of noise being linearly correlated with the signal and introduce a simple technique for improving compressed...... sensing reconstruction from such measurements. The technique is based on a linear model of the correlation of additive noise with the signal. The modification of the reconstruction algorithm based on this model is very simple and has negligible additional computational cost compared to standard...... reconstruction algorithms, but is not known in existing literature. The proposed technique reduces reconstruction error considerably in the case of linearly correlated measurements and noise. Numerical experiments confirm the efficacy of the technique. The technique is demonstrated with application to low...
Statistics of the two-point cross-covariance function of solar oscillations
Nagashima, Kaori; Sekii, Takashi; Gizon, Laurent; Birch, Aaron C.
2016-09-01
Context. The cross-covariance of solar oscillations observed at pairs of points on the solar surface is a fundamental ingredient in time-distance helioseismology. Wave travel times are extracted from the cross-covariance function and are used to infer the physical conditions in the solar interior. Aims: Understanding the statistics of the two-point cross-covariance function is a necessary step towards optimizing the measurement of travel times. Methods: By modeling stochastic solar oscillations, we evaluate the variance of the cross-covariance function as function of time-lag and distance between the two points. Results: We show that the variance of the cross-covariance is independent of both time-lag and distance in the far field, that is, when they are large compared to the coherence scales of the solar oscillations. Conclusions: The constant noise level for the cross-covariance means that the signal-to-noise ratio for the cross-covariance is proportional to the amplitude of the expectation value of the cross-covariance. This observation is important for planning data analysis efforts.
Statistics of the two-point cross-covariance function of solar oscillations
Nagashima, Kaori; Gizon, Laurent; Birch, Aaron C
2016-01-01
Context: The cross-covariance of solar oscillations observed at pairs of points on the solar surface is a fundamental ingredient in time-distance helioseismology. Wave travel times are extracted from the cross-covariance function and are used to infer the physical conditions in the solar interior. Aims: Understanding the statistics of the two-point cross-covariance function is a necessary step towards optimizing the measurement of travel times. Methods: By modeling stochastic solar oscillations, we evaluate the variance of the cross-covariance function as function of time-lag and distance between the two points. Results: We show that the variance of the cross-covariance is independent of both time-lag and distance in the far field, i.e., when they are large compared to the coherence scales of the solar oscillations. Conclusions: The constant noise level for the cross-covariance means that the signal-to-noise ratio for the cross-covariance is proportional to the amplitude of the expectation value of the cross-...
Influence of Multiple Scattering on Two-Pion Correlation Measurements
Institute of Scientific and Technical Information of China (English)
TANG Gui-Xin; ZHANG Wei-Ning; LIU Yi-Ming; HUO Lei; ZHANG Jing-Bo
2004-01-01
@@ Using the relativistic quantum molecular dynamics model, we study the influence of multiple scattering on the result of two-pion correlation measurements. The scales of pion spatial distribution are larger at thermal freezeout than at chemical freeze-out. By varying the value of the parameter of cross section from 0 to 90mb, we find that the sizes of pion source measured by two-particle correlation functions are almost independent of the parameter of cross section. However, λ parameters are sensitive to the parameter of cross section.
Entanglement Measures for Single- and Multi-Reference Correlation Effects
Boguslawski, Katharina; Legeza, Örs; Reiher, Markus
2012-01-01
Electron correlation effects are essential for an accurate ab initio description of molecules. A quantitative a priori knowledge of the single- or multi-reference nature of electronic structures as well as of the dominant contributions to the correlation energy can facilitate the decision regarding the optimum quantum chemical method of choice. We propose concepts from quantum information theory as orbital entanglement measures that allow us to evaluate the single- and multi-reference character of any molecular structure in a given orbital basis set. By studying these measures we can detect possible artifacts of small active spaces.
Heinisch, Philip; Auster, Hans-Ulrich; Richter, Ingo; Hercik, David; Jurado, Eric; Garmier, Romain; Güttler, Carsten; Glassmeier, Karl-Heinz
2016-08-01
As part of the European Space Agency's ROSETTA Mission the Lander PHILAE touched down on comet 67P/Churyumov-Gerasimenko on November 12, 2014. The magnetic field has been measured onboard the orbiter and the lander. The orbiter's tri-axial fluxgate magnetometer RPC-MAG is one of five sensors of the ROSETTA Plasma Consortium. The lander is also equipped with a tri-axial fluxgate magnetometer as part of the ROSETTA Lander Magnetometer and Plasma-Monitor package (ROMAP). This unique setup makes a two point measurement between the two spacecrafts in a relatively small distance of less than 50 km possible. Both magnetometers were switched on during the entire descent, the initial touchdown, the bouncing between the touchdowns and after the final touchdown. We describe a method for attitude determination by correlating magnetic low-frequency waves, which was tested under different conditions and finally used to reconstruct PHILAE's attitude during descent and after landing. In these cases the attitude could be determined with an accuracy of better than ± 5 °. These results were essential not only for PHILAE operations planning but also for the analysis of the obtained scientific data, because nominal sources for this information, like solar panel currents and camera pictures could not provide sufficient information due to the unexpected landing position.
Measurement-induced disturbances and nonclassical correlations of Gaussian states
Mišta, Ladislav; Tatham, Richard; Girolami, Davide; Korolkova, Natalia; Adesso, Gerardo
2010-01-01
We study quantum correlations beyond entanglement in two--mode Gaussian states of continuous variable systems, by means of the measurement-induced disturbance (MID) and its ameliorated version (AMID). In analogy with the recent studies of the Gaussian quantum discord, we define a Gaussian AMID by constraining the optimization to all bi-local Gaussian positive operator valued measurements. We solve the optimization explicitly for relevant families of states, including squeezed thermal states. Remarkably, we find that there is a finite subset of two--mode Gaussian states, comprising pure states, where non-Gaussian measurements such as photon counting are globally optimal for the AMID and realize a strictly smaller state disturbance compared to the best Gaussian measurements. However, for the majority of two--mode Gaussian states the unoptimized MID provides a loose overestimation of the actual content of quantum correlations, as evidenced by its comparison with Gaussian discord. This feature displays strong sim...
Malfunction diagnosis of sensors based on correlation of measurements
Lu, Wei; Teng, Jun; Wen, Runfa; Zhu, Jiayi; Li, Chao
2017-02-01
Structural health monitoring (SHM) is a type of on-site characterization of a real-world full-scale structure that is subjected to the real-world load cases. The fundamental element of SHM is the structural response measurements by sensors, the reliability of which is significant for safety assessment and other SHM applications. The paper proposed a method to diagnosis the fault in sensors using the correlation of measurements. The correlation of the variations of the measurements is examined using the sliding time windows, which is the principle to determine the fault in the sensors. The strain measurements from the SHM system of a real world structure, Shenzhen Bay Stadium, are performed to simulate the faults in sensors and to verify the effectiveness of the proposed method.
Sub-Rayleigh limit imaging via intensity correlation measurements
Institute of Scientific and Technical Information of China (English)
姚旭日; 李龙珍; 刘雪峰; 俞文凯; 翟光杰
2015-01-01
We demonstrate sub-Rayleigh limit imaging of an object via intensity correlation measurements. The image com-pletely unaffected by the disturbance of diffraction-limit is achieved under the condition that the imaging system has an appropriate field of view. The resolution of this sub-Rayleigh limit imaging system is only tied to the lateral resolution of the illumination light.
Purification and correlated measurements of bipartite mixed states
Bouda, J; Bouda, Jan; Buzek, Vladimir
2001-01-01
We prove that all purifications of a non-factorable state (i.e., the state which cannot be expressed in a form $\\rho_{AB}=\\rho_A\\otimes\\rho_B$) are entangled. We also show that for any bipartite state there exists a pair of measurements which are correlated on this state if and only if the state is non-factorable.
Positive-operator-valued measure optimization of classical correlations
Hamieh, S; Kobes, R; Zaraket, H
2004-01-01
We study the problem of optimization over positive-operator-valued measures to extract classical correlation in a bipartite quantum system. The proposed method is applied to binary states only. Moreover, to illustrate this method, an explicit example is studied in detail.
Rapid Measurement of Spectral Characteristics by Correlation Matching Method
Kim, Chol-Sun; Im, Song-Jin
2015-01-01
In this paper, we have established the couple system of a spectroscope, CCD and computer and proposed a method of the rapid measurement on spectral characteristics such as central wavelengths, relative intensities, sensitivity lines and the wavelength range and image pixel of the spectral images of a material by using the correlation matching method for the image discernment of digital spectra.
Measuring weak lensing correlations of Type Ia supernovae
Scovacricchi, D.; Nichol, R. C.; Macaulay, E.; Bacon, D.
2017-03-01
We study the feasibility of detecting weak lensing spatial correlations between supernova (SN) Type Ia magnitudes with present (Dark Energy Survey, DES) and future (Large Synoptic Survey Telescope, LSST) surveys. We investigate the angular auto-correlation function of SN magnitudes (once the background cosmology has been subtracted) and cross-correlation with galaxy catalogues. We examine both analytical and numerical predictions, the latter using simulated galaxy catalogues from the MICE Grand Challenge Simulation. We predict that we will be unable to detect the SN auto-correlation in DES, while it should be detectable with the LSST SN deep fields (15 000 SNe on 70 deg2) at ≃6σ level of confidence (assuming 0.15 mag of intrinsic dispersion). The SN-galaxy cross-correlation function will deliver much higher signal to noise, being detectable in both surveys with an integrated signal to noise of ∼100 (up to 30 arcmin separations). We predict joint constraints on the matter density parameter (Ωm) and the clustering amplitude (σ8) by fitting the auto-correlation function of our mock LSST deep fields. When assuming a Gaussian prior for Ωm, we can achieve a 25 per cent measurement of σ8 from just these LSST supernovae (assuming 0.15 mag of intrinsic dispersion). These constraints will improve significantly if the intrinsic dispersion of SNe Ia can be reduced.
Correlation techniques and measurements of wave-height statistics
Guthart, H.; Taylor, W. C.; Graf, K. A.; Douglas, D. G.
1972-01-01
Statistical measurements of wave height fluctuations have been made in a wind wave tank. The power spectral density function of temporal wave height fluctuations evidenced second-harmonic components and an f to the minus 5th power law decay beyond the second harmonic. The observations of second harmonic effects agreed very well with a theoretical prediction. From the wave statistics, surface drift currents were inferred and compared to experimental measurements with satisfactory agreement. Measurements were made of the two dimensional correlation coefficient at 15 deg increments in angle with respect to the wind vector. An estimate of the two-dimensional spatial power spectral density function was also made.
Temporal correlations and structural memory effects in break junction measurements
DEFF Research Database (Denmark)
Magyarkuti, A.; Lauritzen, Kasper Primdal; Balogh, Zoltan Imre
2017-01-01
that correlations between the opening and subsequent closing traces may indicate structural memory effects in atomic-sized metallic and molecular junctions. Applying these methods on measured and simulated gold metallic contacts as a test system, we show that the surface diffusion induced flattening of the broken......-molecule junctions, we demonstrate pronounced contact memory effects and recovery of the molecule for junctions breaking before atomic chains are formed. However, if chains are pulled the random relaxation of the chain and molecule after rupture prevents opening-closing correlations....
Magnetic noise measurements using cross-correlated Hall sensor arrays
Jung, G.; Ocio, M.; Paltiel, Y.; Shtrikman, H.; Zeldov, E.
2001-01-01
An experimental technique for measuring magnetic fluctuations by means of a double-layer Hall sensor array is described. The technique relies on cross-correlating Hall signals from two independent sensors positioned one above the other in two separate two-dimensional-electron-gas layers of a GaAs/AlGaAs heterostructure. The effectiveness of the technique is demonstrated by a reduction of the magnitude of the background noise floor of the correlated sensors with respect to the noise level of the best single sensor.
Robust Cross-correlation-based Measurement of Clump Sizes in Galaxies
Ali, Kamran; Obreschkow, Danail; Fisher, David B.; Glazebrook, Karl; Damjanov, Ivana; Abraham, Roberto G.; Bassett, Robert
2017-08-01
Stars form in molecular complexes that are visible as giant clouds (˜ {10}5-6 {M}⊙ ) in nearby galaxies and as giant clumps (˜ {10}8-9 {M}⊙ ) in galaxies at redshifts z≈ 1-3. Theoretical inferences on the origin and evolution of these complexes often require robust measurements of their characteristic size, which is hard to measure at limited resolution and often ill-defined due to overlap and quasi-fractal substructure. We show that maximum and luminosity-weighted sizes of clumps seen in star formation maps (e.g., Hα) can be recovered statistically using the two-point correlation function (2PCF) if an approximate stellar surface density map is taken as the normalizing random field. After clarifying the link between Gaussian clumps and the 2PCF analytically, we design a method for measuring the diameters of Gaussian clumps with realistic quasi-fractal substructure. This method is tested using mock images of clumpy disk galaxies at different spatial resolutions and perturbed by Gaussian white noise. We find that the 2PCF can recover the input clump scale at ˜ 20 % accuracy, as long as this scale is larger than the spatial resolution. We apply this method to the local spiral galaxy NGC 5194, as well as to three clumpy turbulent galaxies from the DYNAMO-HST sample. In both cases, our statistical measurements of Hα clump size agree with previous measurements and with the estimated Jeans lengths. However, the new measurements are free from subjective choices when fitting individual clumps.
A kinematic measurement for ductile and brittle failure of materials using digital image correlation
Directory of Open Access Journals (Sweden)
M.M. Reza Mousavi
2016-12-01
Full Text Available This paper addresses some material level test which is done on quasi-brittle and ductile materials in the laboratory. The displacement control experimental program is composed of mortar cylinders under uniaxial compression shows quasi-brittle behavior and seemingly round-section aluminum specimens under uniaxial tension represents ductile behavior. Digital Image Correlation gives full field measurement of deformation in both aluminum and mortar specimens. Likewise, calculating the relative displacement of two points located on top and bottom of virtual LVDT, which is virtually placed on the surface of the specimen, gives us the classical measure of strain. However, the deformation distribution is not uniform all over the domain of specimens mainly due to imperfect nature of experiments and measurement devices. Displacement jumps in the fracture zone of mortar specimens and strain localization in the necking area for the aluminum specimen, which are reflecting different deformation values and deformation gradients, is compared to the other regions. Since the results are inherently scattered, it is usually non-trivial to smear out the stress of material as a function of a single strain value. To overcome this uncertainty, statistical analysis could bring a meaningful way to closely look at scattered results. A large number of virtual LVDTs are placed on the surface of specimens in order to collect statistical parameters of deformation and strain. Values of mean strain, standard deviation and coeffcient of variations for each material are calculated and correlated with the failure type of the corresponding material (either brittle or ductile. The main limiters for standard deviation and coeffcient of variations for brittle and ductile failure, in pre-peak and post-peak behavior are established and presented in this paper. These limiters help us determine whether failure is brittle or ductile without determining of stress level in the material.
Correlating Function and Imaging Measures of the Medial Longitudinal Fasciculus.
Directory of Open Access Journals (Sweden)
Ken Sakaie
Full Text Available To test the validity of diffusion tensor imaging (DTI measures of tissue injury by examining such measures in a white matter structure with well-defined function, the medial longitudinal fasciculus (MLF. Injury to the MLF underlies internuclear ophthalmoparesis (INO.40 MS patients with chronic INO and 15 healthy controls were examined under an IRB-approved protocol. Tissue integrity of the MLF was characterized by DTI parameters: longitudinal diffusivity (LD, transverse diffusivity (TD, mean diffusivity (MD and fractional anisotropy (FA. Severity of INO was quantified by infrared oculography to measure versional disconjugacy index (VDI.LD was significantly lower in patients than in controls in the medulla-pons region of the MLF (p < 0.03. FA was also lower in patients in the same region (p < 0.0004. LD of the medulla-pons region correlated with VDI (R = -0.28, p < 0.05 as did FA in the midbrain section (R = 0.31, p < 0.02.This study demonstrates that DTI measures of brain tissue injury can detect injury to a functionally relevant white matter pathway, and that such measures correlate with clinically accepted evaluation indices for INO. The results validate DTI as a useful imaging measure of tissue integrity.
Resolution of ambiguous radar measurements using a floating bin correlator
Addison, E. R.; Frost, E. L.
It is pointed out that the Chinese Remainder Theorem (Mooney and Skillman, 1970) can be used to yield unambiguous measurements by comparing outputs allocated to fixed integer number bins using integer arithmetic to modulo to the correct bin number. In general, targets straddling two or more bins or the assignment of an incorrect bin number will yield incorrect parameter values. An ambiguity resolution technique using multiple pulse repetition frequency (PRF) data and a sliding floating point window or 'floating bin' to correlate ambiguous centroided Doppler measurements is proposed. An advantage of the technique is that false targets are much less prevalent than in classical techniques. What is more, the same technique may be employed to resolve ambiguous range wherein centroided range measurements are moduloed with the pulse repetition interval associated with each PRF. Results demonstrate that this method is better than conventional approaches in that the number of false targets produced is significantly lower while simultaneoulsy providing a high probability of correlation. In addition, the correlation can be effected in real time.
Bunch Length Measurements With Laser/SR Cross-Correlation
Energy Technology Data Exchange (ETDEWEB)
Miller, Timothy; /Stanford U., Phys. Dept.; Daranciang, Dan; /Stanford U., Phys. Dept.; Lindenberg, Aaron; /Stanford U., Phys. Dept.; Corbett, Jeff; /SLAC; Fisher, Alan; /SLAC; Goodfellow, John; /SLAC; Huang, Xiaobiao; /SLAC; Mok, Walter; /SLAC; Safranek, James; /SLAC; Wen, Haidan; /SLAC
2012-07-06
By operating SPEAR3 in low-{alpha} mode the storage ring can generate synchrotron radiation pulses of order 1ps. Applications include pump-probe x-ray science and the production of THz radiation in the CSR regime. Measurements of the bunch length are difficult, however, because the light intensity is low and streak cameras typically provide resolution of only a few ps. Tests are now underway to resolve the short bunch length using cross-correlation between a 60-fs Ti:Sapphire laser and the visible SR beam in a BBO crystal. In this paper we report on the experimental setup, preliminary measurements and prospects for further improvement.
Bunch Length Measurements With Laser/SR Cross-Correlation
Energy Technology Data Exchange (ETDEWEB)
Miller, Timothy; /Stanford U., Phys. Dept.; Daranciang, Dan; /Stanford U., Phys. Dept.; Lindenberg, Aaron; /Stanford U., Phys. Dept.; Corbett, Jeff; /SLAC; Fisher, Alan; /SLAC; Goodfellow, John; /SLAC; Huang, Xiaobiao; /SLAC; Mok, Walter; /SLAC; Safranek, James; /SLAC; Wen, Haidan; /SLAC
2012-07-06
By operating SPEAR3 in low-{alpha} mode the storage ring can generate synchrotron radiation pulses of order 1ps. Applications include pump-probe x-ray science and the production of THz radiation in the CSR regime. Measurements of the bunch length are difficult, however, because the light intensity is low and streak cameras typically provide resolution of only a few ps. Tests are now underway to resolve the short bunch length using cross-correlation between a 60-fs Ti:Sapphire laser and the visible SR beam in a BBO crystal. In this paper we report on the experimental setup, preliminary measurements and prospects for further improvement.
Two-point discrimination of the upper extremities of healthy Koreans in their 20’s
Koo, Ja-Pung; Kim, Soon-Hee; An, Ho-Jung; Moon, Ok-Gon; Choi, Jung-Hyun; Yun, Young-Dae; Park, Joo-Hyun; Min, Kyoung-Ok
2016-01-01
[Purpose] The present study attempted to measure two-point discrimination in the upper extremities of healthy Koreans in their 20’s. [Subjects and Methods] Using a three-point esthesiometer, we conducted an experiment with a group of 256 college students (128 male and 128 female), attending N University in Chonan, Republic of Korea. [Results] Females showed two-point discrimination at a shorter distance than males at the following points: (i) 5 cm above the elbow joint, the middle part, and 5 cm below the shoulder joint of the anterior upper arm; (ii) 5 cm above the elbow joint and 5 cm below the shoulder joint of the posterior upper arm; (iii) 5 cm above the front of the wrist joint of the forearm; 5 cm below the elbow joint, the palmar part of the distal interphalangeal joint of the thumb, the dorsal part of the distal interphalangeal joint of the middle and little fingers. It was also found that females showed greater two-point discrimination than males in distal regions rather than proximal regions. [Conclusion] The findings of this study will help establish normal values for two-point discrimination of upper extremities of young Koreans in their 20’s. PMID:27134375
3D shape measurement with phase correlation based fringe projection
Kühmstedt, Peter; Munckelt, Christoph; Heinze, Matthias; Bräuer-Burchardt, Christian; Notni, Gunther
2007-06-01
Here we propose a method for 3D shape measurement by means of phase correlation based fringe projection in a stereo arrangement. The novelty in the approach is characterized by following features. Correlation between phase values of the images of two cameras is used for the co-ordinate calculation. This work stands in contrast to the sole usage of phase values (phasogrammetry) or classical triangulation (phase values and image co-ordinates - camera raster values) for the determination of the co-ordinates. The method's main advantage is the insensitivity of the 3D-coordinates from the absolute phase values. Thus it prevents errors in the determination of the co-ordinates and improves robustness in areas with interreflections artefacts and inhomogeneous regions of intensity. A technical advantage is the fact that the accuracy of the 3D co-ordinates does not depend on the projection resolution. Thus the achievable quality of the 3D co-ordinates can be selectively improved by the use of high quality camera lenses and can participate in improvements in modern camera technologies. The presented new solution of the stereo based fringe projection with phase correlation makes a flexible, errortolerant realization of measuring systems within different applications like quality control, rapid prototyping, design and CAD/CAM possible. In the paper the phase correlation method will be described in detail. Furthermore, different realizations will be shown, i.e. a mobile system for the measurement of large objects and an endoscopic like system for CAD/CAM in dental industry.
Nonlinear ultrasonic measurements based on cross-correlation filtering techniques
Yee, Andrew; Stewart, Dylan; Bunget, Gheorghe; Kramer, Patrick; Farinholt, Kevin; Friedersdorf, Fritz; Pepi, Marc; Ghoshal, Anindya
2017-02-01
Cyclic loading of mechanical components promotes the formation of dislocation dipoles in metals, which can serve as precursors to crack nucleation and ultimately lead to failure. In the laboratory setting, an acoustic nonlinearity parameter has been assessed as an effective indicator for characterizing the progression of fatigue damage precursors. However, the need to use monochromatic waves of medium-to-high acoustic energy has presented a constraint, making it problematic for use in field applications. This paper presents a potential approach for field measurement of acoustic nonlinearity by using general purpose ultrasonic pulser-receivers. Nonlinear ultrasonic measurements during fatigue testing were analyzed by the using contact and immersion pulse-through method. A novel cross-correlation filtering technique was developed to extract the fundamental and higher harmonic waves from the signals. As in the case of the classic harmonic generation, the nonlinearity parameters of the second and third harmonics indicate a strong correlation with fatigue cycles. Consideration was given to potential nonlinearities in the measurement system, and tests have confirmed that measured second harmonic signals exhibit a linear dependence on the input signal strength, further affirming the conclusion that this parameter relates to damage precursor formation from cyclic loading.
Matrix-based concordance correlation coefficient for repeated measures.
Hiriote, Sasiprapa; Chinchilli, Vernon M
2011-09-01
In many clinical studies, Lin's concordance correlation coefficient (CCC) is a common tool to assess the agreement of a continuous response measured by two raters or methods. However, the need for measures of agreement may arise for more complex situations, such as when the responses are measured on more than one occasion by each rater or method. In this work, we propose a new CCC in the presence of repeated measurements, called the matrix-based concordance correlation coefficient (MCCC) based on a matrix norm that possesses the properties needed to characterize the level of agreement between two p× 1 vectors of random variables. It can be shown that the MCCC reduces to Lin's CCC when p= 1. For inference, we propose an estimator for the MCCC based on U-statistics. Furthermore, we derive the asymptotic distribution of the estimator of the MCCC, which is proven to be normal. The simulation studies confirm that overall in terms of accuracy, precision, and coverage probability, the estimator of the MCCC works very well in general cases especially when n is greater than 40. Finally, we use real data from an Asthma Clinical Research Network (ACRN) study and the Penn State Young Women's Health Study for demonstration.
Measuring Fisher information accurately in correlated neural populations.
Kanitscheider, Ingmar; Coen-Cagli, Ruben; Kohn, Adam; Pouget, Alexandre
2015-06-01
Neural responses are known to be variable. In order to understand how this neural variability constrains behavioral performance, we need to be able to measure the reliability with which a sensory stimulus is encoded in a given population. However, such measures are challenging for two reasons: First, they must take into account noise correlations which can have a large influence on reliability. Second, they need to be as efficient as possible, since the number of trials available in a set of neural recording is usually limited by experimental constraints. Traditionally, cross-validated decoding has been used as a reliability measure, but it only provides a lower bound on reliability and underestimates reliability substantially in small datasets. We show that, if the number of trials per condition is larger than the number of neurons, there is an alternative, direct estimate of reliability which consistently leads to smaller errors and is much faster to compute. The superior performance of the direct estimator is evident both for simulated data and for neuronal population recordings from macaque primary visual cortex. Furthermore we propose generalizations of the direct estimator which measure changes in stimulus encoding across conditions and the impact of correlations on encoding and decoding, typically denoted by Ishuffle and Idiag respectively.
Theoretical model of blood flow measurement by diffuse correlation spectroscopy
Sakadžić, Sava; Boas, David A.; Carp, Stefan
2017-02-01
Diffuse correlation spectroscopy (DCS) is a noninvasive method to quantify tissue perfusion from measurements of the intensity temporal autocorrelation function of diffusely scattered light. However, DCS autocorrelation function measurements in tissue better match theoretical predictions based on the diffusive motion of the scatterers than those based on a model where the advective nature of blood flow dominates the stochastic properties of the scattered light. We have recently shown using Monte Carlo (MC) simulations and assuming a simplistic vascular geometry and laminar flow profile that the diffusive nature of the DCS autocorrelation function decay is likely a result of the shear-induced diffusion of the red blood cells. Here, we provide theoretical derivations supporting and generalizing the previous MC results. Based on the theory of diffusing-wave spectroscopy, we derive an expression for the autocorrelation function along the photon path through a vessel that takes into account both diffusive and advective scatterer motion, and we provide the solution for the DCS autocorrelation function in a semi-infinite geometry. We also derive the correlation diffusion and correlation transfer equation, which can be applied for an arbitrary sample geometry. Further, we propose a method to take into account realistic vascular morphology and flow profile.
Xiao, Xing; Yao, Yao; Xie, Ying-Mao; Wang, Xing-Hua; Li, Yan-Ling
2016-09-01
Based on the quantum technique of weak measurement, we propose a scheme to protect the entanglement from correlated amplitude damping decoherence. In contrast to the results of memoryless amplitude damping channel, we show that the memory effects play a significant role in the suppression of entanglement sudden death and protection of entanglement under severe decoherence. Moreover, we find that the initial entanglement could be drastically amplified by the combination of weak measurement and quantum measurement reversal even under the correlated amplitude damping channel. The underlying mechanism can be attributed to the probabilistic nature of weak measurements.
Measuring capital market efficiency: Global and local correlations structure
Kristoufek, Ladislav; Vosvrda, Miloslav
2013-01-01
We introduce a new measure for capital market efficiency. The measure takes into consideration the correlation structure of the returns (long-term and short-term memory) and local herding behavior (fractal dimension). The efficiency measure is taken as a distance from an ideal efficient market situation. The proposed methodology is applied to a portfolio of 41 stock indices. We find that the Japanese NIKKEI is the most efficient market. From a geographical point of view, the more efficient markets are dominated by the European stock indices and the less efficient markets cover mainly Latin America, Asia and Oceania. The inefficiency is mainly driven by a local herding, i.e. a low fractal dimension.
Estimating correlation for a real-time measure of connectivity.
Arunkumar, Akhil; Panday, Ashish; Joshi, Bharat; Ravindran, Arun; Zaveri, Hitten P
2012-01-01
There has recently been considerable interest in connectivity analysis of fMRI and scalp and intracranial EEG time-series. The computational requirements of the pair-wise correlation (PWC), the core time-series measure used to estimate connectivity, presents a challenge to the real-time estimation of the PWC between all pairs of multiple time-series. We describe a parallel algorithm for computing PWC in real-time for streaming data from multiple channels. The algorithm was implemented on the Intel Xeon™ and IBM Cell Broadband Engine™ platforms. We evaluated time to estimate correlation for signals recorded with different acquisition parameters as a comparison to real-time constraints. We demonstrate that the execution time of these efficient implementations meet real-time constraints in most instances.
Offset balancing in pseudo-correlation radiometers for CMB measurements
Mennella, A.; Bersanelli, M.; Seiffert, M.; Kettle, D.; Roddis, N.; Wilkinson, A.; Meinhold, P.
2003-11-01
Radiometeric CMB measurements need to be highly stable and this stability is best obtained with differential receivers. The residual 1/f noise in the differential output is strongly dependent on the radiometer input offset which can be cancelled using various balancing strategies. In this paper we discuss a software method implemented in the PLANCK-LFI pseudo-correlation receivers which uses a tunable gain modulation factor, r, in the sky-load difference. Numerical simulations and experimental data show how proper tuning of the parameter r ensures a very stable differential output with knee frequencies of the order of few mHz. Various approaches to calculate r using the radiometer total power data are discussed with some examples relevant to PLANCK-LFI. Although the paper focuses on pseudo-correlation receivers and the examples are relative to PLANCK-LFI, the proposed method and its analysis is general and can be applied to a large class of differential radiometric receivers.
Offset balancing in pseudo-correlation radiometers for CMB measurements
Mennella, A; Seiffert, M; Kettle, D; Roddis, N; Wilkinson, A; Meinhold, P; Mennella, Aniello; Bersanelli, Marco; Seiffert, Michael; Kettle, Danielle; Roddis, Neil; Wilkinson, Althea; Meinhold, Peter
2003-01-01
Radiometeric CMB measurements need to be highly stable and this stability is best obtained with differential receivers. The residual 1/f noise in the differential output is strongly dependent on the radiometer input offset which can be cancelled using various balancing strategies. In this paper we discuss a software method implemented in the Planck-LFI pseudo-correlation receivers which uses a tunable "gain modulation factor, r, in the sky-load difference. Numerical simulations and experimental data show how proper tuning of the parameter r ensures a very stable differential output with knee frequencies of the order of few mHz. Various approaches to calculate r using the radiometer total power data are discussed with some examples relevant to Planck-LFI. Although the paper focuses on pseudo-correlation receivers and the examples are relative to Planck-LFI, the proposed method and its analysis is general and can be applied to a large class of differential radiometric receivers.
Measuring peptide mass spectrum correlation using the quantum Grover algorithm.
Choo, Keng Wah
2007-03-01
We investigated the use of the quantum Grover algorithm in the mass-spectrometry-based protein identification process. The approach coded the mass spectra on a quantum register and uses the Grover search algorithm for searching multiple solutions to find matches from a database. Measurement of the fidelity between the input and final states was used to quantify the similarity between the experimental and theoretical spectra. The optimal number of iteration is proven to be pi/4sqrt[N/k] , where k refers to the number of marked states. We found that one iteration is sufficient for the search if we let more that 62% of the N states be marked states. By measuring the fidelity after only one iteration of Grover search, we discovered that it resembles that of the correlation-based measurement used in the existing protein identification software. We concluded that the quantum Grover algorithm can be adapted for a correlation-based mass spectra database search, provided that decoherence can be kept to a minimum.
Bayesian Concordance Correlation Coefficient with Application to Repeatedly Measured Data
Directory of Open Access Journals (Sweden)
Atanu BHATTACHARJEE
2015-10-01
Full Text Available Objective: In medical research, Lin's classical concordance correlation coefficient (CCC is frequently applied to evaluate the similarity of the measurements produced by different raters or methods on the same subjects. It is particularly useful for continuous data. The objective of this paper is to propose the Bayesian counterpart to compute CCC for continuous data. Material and Methods: A total of 33 patients of astrocytoma brain treated in the Department of Radiation Oncology at Malabar Cancer Centre is enrolled in this work. It is a continuous data of tumor volume and tumor size repeatedly measured during baseline pretreatment workup and post surgery follow-ups for all patients. The tumor volume and tumor size are measured separately by MRI and CT scan. The agreement of measurement between MRI and CT scan is calculated through CCC. The statistical inference is performed through Markov Chain Monte Carlo (MCMC technique. Results: Bayesian CCC is found suitable to get prominent evidence for test statistics to explore the relation between concordance measurements. The posterior mean estimates and 95% credible interval of CCC on tumor size and tumor volume are observed with 0.96(0.87,0.99 and 0.98(0.95,0.99 respectively. Conclusion: The Bayesian inference is adopted for development of the computational algorithm. The approach illustrated in this work provides the researchers an opportunity to find out the most appropriate model for specific data and apply CCC to fulfill the desired hypothesis.
Oxygen measurement by multimode diode lasers employing gas correlation spectroscopy.
Lou, Xiutao; Somesfalean, Gabriel; Chen, Bin; Zhang, Zhiguo
2009-02-10
Multimode diode laser (MDL)-based correlation spectroscopy (COSPEC) was used to measure oxygen in ambient air, thereby employing a diode laser (DL) having an emission spectrum that overlaps the oxygen absorption lines of the A band. A sensitivity of 700 ppm m was achieved with good accuracy (2%) and linearity (R(2)=0.999). For comparison, measurements of ambient oxygen were also performed by tunable DL absorption spectroscopy (TDLAS) technique employing a vertical cavity surface emitting laser. We demonstrate that, despite slightly degraded sensitivity, the MDL-based COSPEC-based oxygen sensor has the advantages of high stability, low cost, ease-of-use, and relaxed requirements in component selection and instrument buildup compared with the TDLAS-based instrument.
APPLICATION OF NOVEL NEUTRON CORRELATION TECHNIQUES TO NUCLEAR MATERIAL MEASUREMENTS
Energy Technology Data Exchange (ETDEWEB)
Sale, K
2006-06-09
Confirmation of the fissile mass of a system containing plutonium can be done using neutron multiplicity techniques. This can be accomplished with a detector system that is smaller and less costly than a standard neutron multiplicity counter (NMC). Also the fissile mass of a uranium containing system can be confirmed by passive means. Recent work at Lawrence Livermore National Laboratory has demonstrated that simple slab neutron detectors and a novel approach to data acquisition and analysis can be used to make an accurate measurement of the mass of fissile materials. Purely passive measurement of kilogram quantities of highly enriched uranium (HEU) have also been shown to be feasible. In this paper we discuss calculational tools for assessing the application of these techniques to fissile material transparency regimes. The tools required to adequately model the correlations and their application will be discussed.
New two-point scleral-fixation technique for foldable intraocular lenses with four hollow haptics.
Liu, He-Ting; Jiang, Zheng-Xuan; Tao, Li-Ming
2016-01-01
The study was to report a new two-point scleral-fixation technique for foldable intraocular lenses with four haptics. Lenses were slid into the anterior chamber from a 2.8 mm corneal incision and fixed under two sclera flaps at two opposite points. The postoperative best-corrected visual acuities (BCVAs) of all patients were significantly better than their preoperative BCVA. The results demonstrate that two-point, scleral fixations of foldable, intraocular lenses might be practicable and effective.
Accurate measurement of curvilinear shapes by Virtual Image Correlation
Semin, B.; Auradou, H.; François, M. L. M.
2011-10-01
The proposed method allows the detection and the measurement, in the sense of metrology, of smooth elongated curvilinear shapes. Such measurements are required in many fields of physics, for example: mechanical engineering, biology or medicine (deflection of beams, fibers or filaments), fluid mechanics or chemistry (detection of fronts). Contrary to actual methods, the result is given in an analytical form of class C∞ (and not a finite set of locations or pixels) thus curvatures and slopes, often of great interest in science, are given with good confidence. The proposed Virtual Image Correlation (VIC) method uses a virtual beam, an image which consists in a lateral expansion of the curve with a bell-shaped gray level. This figure is deformed until it fits the best the physical image with a method issued from the Digital Image Correlation method in use in solid mechanics. The precision of the identification is studied in a benchmark and successfully compared to two state-of-the-art methods. Three practical examples are given: a bar bending under its own weight, a thin fiber transported by a flow within a fracture and a thermal front. The first allows a comparison with theoretical solution, the second shows the ability of the method to deal with complex shapes and crossings and the third deals with ill-defined image.
Strongly correlated two-dimensional plasma explored from entropy measurements.
Kuntsevich, A Y; Tupikov, Y V; Pudalov, V M; Burmistrov, I S
2015-06-23
Charged plasma and Fermi liquid are two distinct states of electronic matter intrinsic to dilute two-dimensional electron systems at elevated and low temperatures, respectively. Probing their thermodynamics represents challenge because of lack of an adequate technique. Here, we report a thermodynamic method to measure the entropy per electron in gated structures. Our technique appears to be three orders of magnitude superior in sensitivity to a.c. calorimetry, allowing entropy measurements with only 10(8) electrons. This enables us to investigate the correlated plasma regime, previously inaccessible experimentally in two-dimensional electron systems in semiconductors. In experiments with clean two-dimensional electron system in silicon-based structures, we traced entropy evolution from the plasma to Fermi liquid regime by varying electron density. We reveal that the correlated plasma regime can be mapped onto the ordinary non-degenerate Fermi gas with an interaction-enhanced temperature-dependent effective mass. Our method opens up new horizons in studies of low-dimensional electron systems.
Correlating Atom Probe Crystallographic Measurements with Transmission Kikuchi Diffraction Data.
Breen, Andrew J; Babinsky, Katharina; Day, Alec C; Eder, K; Oakman, Connor J; Trimby, Patrick W; Primig, Sophie; Cairney, Julie M; Ringer, Simon P
2017-03-14
Correlative microscopy approaches offer synergistic solutions to many research problems. One such combination, that has been studied in limited detail, is the use of atom probe tomography (APT) and transmission Kikuchi diffraction (TKD) on the same tip specimen. By combining these two powerful microscopy techniques, the microstructure of important engineering alloys can be studied in greater detail. For the first time, the accuracy of crystallographic measurements made using APT will be independently verified using TKD. Experimental data from two atom probe tips, one a nanocrystalline Al-0.5Ag alloy specimen collected on a straight flight-path atom probe and the other a high purity Mo specimen collected on a reflectron-fitted instrument, will be compared. We find that the average minimum misorientation angle, calculated from calibrated atom probe reconstructions with two different pole combinations, deviate 0.7° and 1.4°, respectively, from the TKD results. The type of atom probe and experimental conditions appear to have some impact on this accuracy and the reconstruction and measurement procedures are likely to contribute further to degradation in angular resolution. The challenges and implications of this correlative approach will also be discussed.
Esmaeli, Farzad; Shirmohammadi, Adileh; Faramarzie, Masoumeh; Abolfazli, Nader; Rasouli, Hossein; Fallahi, Saied
2012-01-01
Background Diagnosis and accuracy in determining the exact location, extent and configuration of bony defects of the jaw are of utmost importance to determine prognosis, treatment planning and long-term preservation of teeth. If relatively accurate diagnosis can be established by radiography, proper treatment planning prior to treatment procedures will be possible. Objectives The aim of the present study was to assess the correlation between indirect digital radiographic measurements and clinical measurements in determining the topography of interproximal bony defects. Patients and Methods Twenty interproximal bony defects, preferably in the mandibular and maxillary 5↔5 area were selected and radiographed using the parallel periapical technique. The radiographs were corrected and digitized on a computer using “Linear Measurement” software; then the three parameters of the base of defect (BD), alveolar crest (AC) and cementoenamel junction (CEJ) were determined using a software. Subsequent to radiographic measurements, clinical measurements were carried out meticulously during flap procedures. Then linear measurements were carried out using a periodontal probe to determine the defect depth and its mesiodistal width. Then the amount of correlation between these two measurements was assessed by Pearson's correlation coefficient. Results The correlation between clinical and radiographic measurements in defect depth determination, in the evaluation of defect angle and in determination of defect width were 88%, 98% and 90%, respectively. Conclusions Indirect digital radiographic technique can be used to diagnose intra-osseous defects, providing a better opportunity to treat bony defects. PMID:23329969
The Effect of Error Correlation on Interfactor Correlation in Psychometric Measurement
Westfall, Peter H.; Henning, Kevin S. S.; Howell, Roy D.
2012-01-01
This article shows how interfactor correlation is affected by error correlations. Theoretical and practical justifications for error correlations are given, and a new equivalence class of models is presented to explain the relationship between interfactor correlation and error correlations. The class allows simple, parsimonious modeling of error…
Vriens, J P M; van der Glas, H W
2009-11-01
The threshold value of a sensory test provides a numerical measure of the sensory function. In order to decide whether a threshold value from an affected site indicates 'abnormal' sensory function, it can be compared with normal values from a healthy control population. The aim of this study was to extend current information on normal values for static light touch and static two-point discrimination for facial sites. Using simple hand-held devices, 95% upper limits of confidence intervals of threshold values were determined for facial sites other than those studied previously and for a large sample of 100 healthy subjects. The MacKinnon-Dellon Disk-Criminator and the Aesthesiometer were used to measure novel normal values of two-point discrimination. As threshold values for two-point discrimination from the Aesthesiometer were similar to those obtained using the Disk-Criminator, the use of the Aesthesiometer might not be indicated. Apart from the Pressure Specified Sensory Device (a device with pressure control), Semmes-Weinstein nylon monofilaments and the Disk-Criminator are useful devices for studying sensory function, in particular under clinical test conditions in which easy and fast application are advantageous.
Sonographic Measurement of Renal Dimensions in Adults and its Correlates
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Iffat Yazdani
2012-09-01
Full Text Available Background: Unilateral or bilateral changes in kidney size are manifested by many renal diseases and to recognize these anatomical deviations, it is important to have standard sonographic measurements for appropriate comparison. Our primary aim was to determine a normal range of values for renal dimensions in our asymptomatic adult population and to correlate renal length with measures of renal function as a secondary objective. Methods: A cross-sectional population survey was conducted at two spaced-out densely populated areas in the city of Karachi, Pakistan. Ultrasound was preformed and blood samples collected from 225 healthy individuals with no known renal pathology and with normal calculated GFR. Results: Mean kidney lengths were 9.85cm (95% CI: 9.74-9.95 cm on right side and 10.0 cm (9.85-10.1 cm on left. The mean width was 4.61cm (95%CI: 4.53 – 4.68cm, cortical thickness 1.46 cm (CI 1.43-1.49cm with estimated average kidney volume 35.7 cm3 (CI: 34.1-36.5 cm3. Males had larger kidney sizes than females (p < 0.001; age however was only associated with a decrease in renal length after ages 70 and above.(p=0.001 Renal length best correlated with body weight (correlation coefficient 0.384 .eGFR, representative of renal function also positively correlated with renal length (Coefficient 0.415. A multivariate analysis showed male gender (OR 1.60, age (OR 0.89, weight (OR 1.02 and height (OR 7.77 to be significant independent predictors of renal length. Conclusion: We established the normal values for renal dimensions in our adult population. Our study signifies the potential of ultrasound as a useful tool for diagnostic and follow-up purposes of kidney–associated diseases. By extending this research and including data from other parts of the country; we can formulate a gender and age specific nomogram for kidney dimensions for adequate comparison in evaluation of kidney diseases.
A Measurement of the Galaxy Group-Thermal Sunyaev-Zel'dovich Effect Cross-Correlation Function
Vikram, Vinu; Jain, Bhuvnesh
2016-01-01
Stacking cosmic microwave background (CMB) maps around known galaxy clusters and groups provides a powerful probe of the distribution of hot gas in these systems via the Sunyaev-Zel'dovich (SZ) effect. A stacking analysis allows one to detect the average SZ signal around low mass halos, and to extend measurements out to large scales, which are too faint to detect individually in the SZ or in X-ray emission. In addition, cross correlations between SZ maps and other tracers of large-scale structure (with known redshifts) can be used to extract the redshift-dependence of the SZ background. Motivated by these exciting prospects, we measure the two-point cross-correlation function between a catalog of $\\sim 380,000$ galaxy groups (with redshifts spanning $z=0.01-0.2$) from the Sloan Digital Sky Survey (SDSS) and Compton-y parameter maps constructed by the Planck collaboration. We find statistically significant correlations between the group catalog and Compton-y maps in each of six separate mass bins, with estimat...
Measuring correlations in non-separable vector beams using projective measurements
Subramanian, Keerthan
2016-01-01
In quantum mechanics, two particles are said to be entangled if the composite wavefunction is non-separable. Separating the two particles and measuring their coincidences as was done in the Aspect experiment leads to a modulated correlation between the polarization states of the two particles. In this article we demonstrate a similar experiment to look at a system whose two degrees of freedom (DoF)- polarization and mode - are entangled, ie the system can be modelled as a non-separable function in the Hilbert space. We propose an interferometric method to perform projective measurements that leads to correlations as seen for entangled quantum particles.
Spam Source Clustering by Constructing Spammer Network with Correlation Measure
Shin, Jeongkyu; Kim, Seunghwan
Spam filtering is one of the most challenging problems in electric message systems. In general, recent studies on specifying real spam source are based on content filtering because spammers usually falsify their origin. We propose a method to specify spam source based on structural analysis with complex network. We assume that each spam sources either has the same victim list or uses the same spam-hosting program. We treat spam source - target relationship as a bipartite network and construct weighted spam source network by network projection using correlation measure. We find that community clustering methods are inappropriate with spammer network. We group spammers with gradient-based grouping, which uses correlations between nodes as gradient between nodes. We convert them into local minima, which helps to cluster spammers into a few spam source groups. We investigate the weblog spam data with the proposed method and validate it. The method that we propose can be applied to diverse categorization problems, such as multiple text categorization and network subunit clustering.
Viscosity Measurements and Correlation of the Squalane + CO2 Mixture
Tomida, D.; Kumagai, A.; Yokoyama, C.
2007-02-01
Experimental results for the viscosity of squalane + CO2 mixtures are reported. The viscosities were measured using a rolling ball viscometer. The experimental temperatures were 293.15, 313.15, 333.15, and 353.15 K, and pressures were 10.0, 15.0, and 20.0 MPa. The CO2 mole fraction of the mixtures varied from 0 to 0.417. The experimental uncertainties in viscosity were estimated to be within ±3.0%. The viscosity of the mixtures decreased with an increase in the CO2 mole fraction. The experimental data were compared with predictions from the Grunberg-Nissan and McAllister equations, which correlated the experimental data with maximum deviations of 10 and 8.7%, respectively.
Influence of the surface hydrophobicity on fluorescence correlation spectroscopy measurements
Boutin, Céline; Jaffiol, Rodolphe; Plain, Jérome; Royer, Pascal
2007-02-01
Fluorescence correlation spectroscopy (FCS) is a powerful experimental technique used to analyze the diffusion at the single molecule level in solution. FCS is based on the temporal autocorrelation of fluorescent signal generated by dye molecules diffusing through a small confocal volume. These measurements are mostly carried out in a chambered coverglass, close to the glass substrate. In this report, we discuss how the chemical nature of the glass-water interface may interact with the free diffusion of molecules. Our results reveal a strong influence, up to a few Î¼m from the interface, of the surface hydrophobicity degree. This influence is assessed through the relative weight of the two dimension diffusion process observed at the vicinity of the surface.
Directory of Open Access Journals (Sweden)
Farzad Esmaeli
2012-01-01
Full Text Available Background: Diagnosis and accuracy in determining the exact location, extent and configurationof bony defects of the jaw are of utmost importance to determine prognosis,treatment planning and long-term preservation of teeth. If relatively accurate diagnosiscan be established by radiography, proper treatment planning prior to treatment procedureswill be possible.Objectives: The aim of the present study was to assess the correlation between indirectdigital radiographic measurements and clinical measurements in determining the topographyof interproximal bony defects.Patients and Methods: Twenty interproximal bony defects, preferably in the mandibularand maxillary 5↔5 area were selected and radiographed using the parallel periapical technique.The radiographs were corrected and digitized on a computer using “Linear Measurement”software; then the three parameters of the base of defect (BD, alveolar crest(AC and cementoenamel junction (CEJ were determined using a software. Subsequentto radiographic measurements, clinical measurements were carried out meticulouslyduring flap procedures. Then linear measurements were carried out using a periodontalprobe to determine the defect depth and its mesiodistal width. Then the amount of correlationbetween these two measurements was assessed by Pearson's correlation coefficient.Results: The correlation between clinical and radiographic measurements in defect depthdetermination, in the evaluation of defect angle and in determination of defect widthwere 88%, 98% and 90%, respectively.Conclusions: Indirect digital radiographic technique can be used to diagnose intra-osseousdefects, providing a better opportunity to treat bony defects.
Mistakes and Pitfalls Associated with Two-Point Compression Ultrasound for Deep Vein Thrombosis
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Tony Zitek, MD
2016-03-01
Full Text Available Introduction: Two-point compression ultrasound is purportedly a simple and accurate means to diagnose proximal lower extremity deep vein thrombosis (DVT, but the pitfalls of this technique have not been fully elucidated. The objective of this study is to determine the accuracy of emergency medicine resident-performed two-point compression ultrasound, and to determine what technical errors are commonly made by novice ultrasonographers using this technique. Methods: This was a prospective diagnostic test assessment of a convenience sample of adult emergency department (ED patients suspected of having a lower extremity DVT. After brief training on the technique, residents performed two-point compression ultrasounds on enrolled patients. Subsequently a radiology department ultrasound was performed and used as the gold standard. Residents were instructed to save videos of their ultrasounds for technical analysis. Results: Overall, 288 two-point compression ultrasound studies were performed. There were 28 cases that were deemed to be positive for DVT by radiology ultrasound. Among these 28, 16 were identified by the residents with two-point compression. Among the 260 cases deemed to be negative for DVT by radiology ultrasound, 10 were thought to be positive by the residents using two-point compression. This led to a sensitivity of 57.1% (95% CI [38.8-75.5] and a specificity of 96.1% (95% CI [93.8-98.5] for resident-performed two-point compression ultrasound. This corresponds to a positive predictive value of 61.5% (95% CI [42.8-80.2] and a negative predictive value of 95.4% (95% CI [92.9-98.0]. The positive likelihood ratio is 14.9 (95% CI [7.5-29.5] and the negative likelihood ratio is 0.45 (95% CI [0.29-0.68]. Video analysis revealed that in four cases the resident did not identify a DVT because the thrombus was isolated to the superior femoral vein (SFV, which is not evaluated by two-point compression. Moreover, the video analysis revealed that the
Rigid internal fixation of zygoma fractures: A comparison of two-point and three-point fixation
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Parashar Atul
2007-01-01
Full Text Available Background: Displaced fractures of the zygomatic bone can result in significant functional and aesthetic sequelae. Therefore the treatment must achieve adequate and stable reduction at fracture sites so as to restore the complex multidimensional relationship of the zygoma to the surrounding craniofacial skeleton. Many experimental biophysical studies have compared stability of zygoma after one, two and three-point fixation with mini plates. We conducted a prospective clinical study comparing functional and aesthetic results of two-point and three-point fixation with mini plates in patients with fractures of zygoma. Materials and Methods: Twenty-two patients with isolated zygomatic fractures over a period of one year were randomly assigned into two-point and three-point fixation groups. Results of fixation were analyzed after completion of three months. This included clinical, radiological and photographic evaluation. Results: The three-point fixation group maintained better stability at fracture sites resulting in decreased incidence of dystopia and enophthalmos. This group also had better malar projection and malar height as measured radiologically, when compared with the two-point fixation group. Conclusion: We recommend three-point rigid fixation of fractured zygoma after accurate reduction so as to maintain adequate stabilization against masticatory forces during fracture healing phase.
Measurement and correlates of empathy among female Japanese physicians.
Kataoka, Hitomi U; Koide, Norio; Hojat, Mohammadreza; Gonnella, Joseph S
2012-06-22
The measurement of empathy is important in the assessment of physician competence and patient outcomes. The prevailing view is that female physicians have higher empathy scores compared with male physicians. In Japan, the number of female physicians has increased rapidly in the past ten years. In this study, we focused on female Japanese physicians and addressed factors that were associated with their empathic engagement in patient care. The Jefferson Scale of Empathy (JSE) was translated into Japanese by using the back-translation procedure, and was administered to 285 female Japanese physicians. We designed this study to examine the psychometrics of the JSE and group differences among female Japanese physicians. The item-total score correlations of the JSE were all positive and statistically significant, ranging from .20 to .54, with a median of .41. The Cronbach's coefficient alpha was .81. Female physicians who were practicing in "people-oriented" specialties obtained a significantly higher mean empathy score than their counterparts in "procedure-" or "technology-oriented" specialties. In addition, physicians who reported living with their parents in an extended family or living close to their parents, scored higher on the JSE than those who were living alone or in a nuclear family. Our results provide support for the measurement property and reliability of the JSE in a sample of female Japanese physicians. The observed group differences associated with specialties and living arrangement may have implications for sustaining empathy. In addition, recognizing these factors that reinforce physicians' empathy may help physicians to avoid career burnout.
A fast digital image correlation method for deformation measurement
Pan, Bing; Li, Kai
2011-07-01
Fast and high-accuracy deformation analysis using digital image correlation (DIC) has been increasingly important and highly demanded in recent years. In literature, the DIC method using the Newton-Rapshon (NR) algorithm has been considered as a gold standard for accurate sub-pixel displacement tracking, as it is insensitive to the relative deformation and rotation of the target subset and thus provides highest sub-pixel registration accuracy and widest applicability. A significant drawback of conventional NR-algorithm-based DIC method, however, is its extremely huge computational expense. In this paper, a fast DIC method is proposed deformation measurement by effectively eliminating the repeating redundant calculations involved in the conventional NR-algorithm-based DIC method. Specifically, a reliability-guided displacement scanning strategy is employed to avoid time-consuming integer-pixel displacement searching for each calculation point, and a pre-computed global interpolation coefficient look-up table is utilized to entirely eliminate repetitive interpolation calculation at sub-pixel locations. With these two approaches, the proposed fast DIC method substantially increases the calculation efficiency of the traditional NR-algorithm-based DIC method. The performance of proposed fast DIC method is carefully tested on real experimental images using various calculation parameters. Results reveal that the computational speed of the present fast DIC is about 120-200 times faster than that of the traditional method, without any loss of its measurement accuracy
Deformation-phase measurement by digital speckle correlation method
Zhao, Ran; Sun, Ping
2016-10-01
A novel algorithm which extracts the out-of-plane component of deformation phase from two continuous fringe patterns is proposed. The velocity field between two consecutive frames is estimated by digital speckle correlation method (DSCM). After that, according to the optical flow constrained equation, the whole-field deformation-phase map is obtained by the estimations of the velocity field and the local frequency of the original image. The operation of the proposed method is simple compared with other phase demodulation methods. Moreover, the new method works perfectly at the areas with dense fringes. In this paper, the proposed algorithm is introduced. Meanwhile, in order to verify the effectiveness, the new algorithm is applied to simulated interferogram and real fringe pattern with a centrally loaded and edge-clamped plate. The results of simulation and experiment show that the new method can demodulate the out-of-plane component of deformation phase from the visible in-plane velocity field without unwrapping process. Further, dynamic deformation-phase extraction will be realized when we know the time interval of two continuous images. The proposed algorithm provides a new approach for whole-field deformation-phase measurement and dynamic deformation measurement.
Holographic two-point functions for 4d log-gravity
Johansson, Niklas; Zojer, Thomas
2012-01-01
We compute holographic one- and two-point functions of critical higher curvature gravity in four dimensions. The two most important operators are the stress tensor and its logarithmic partner, sourced by ordinary massless and by logarithmic non-normalisable gravitons, respectively. In addition, the logarithmic gravitons source two ordinary operators, one with spin-one and one with spin-zero. The one-point function of the stress tensor vanishes for all Einstein solutions, but has a non-zero contribution from logarithmic gravitons. The two-point functions of all operators match the expectations from a three-dimensional logarithmic conformal field theory.
Numerical methods for stiff systems of two-point boundary value problems
Flaherty, J. E.; Omalley, R. E., Jr.
1983-01-01
Numerical procedures are developed for constructing asymptotic solutions of certain nonlinear singularly perturbed vector two-point boundary value problems having boundary layers at one or both endpoints. The asymptotic approximations are generated numerically and can either be used as is or to furnish a general purpose two-point boundary value code with an initial approximation and the nonuniform computational mesh needed for such problems. The procedures are applied to a model problem that has multiple solutions and to problems describing the deformation of thin nonlinear elastic beam that is resting on an elastic foundation.
Verified solutions of two-point boundary value problems for nonlinear oscillators
Bünger, Florian
Using techniques introduced by Nakao [4], Oishi [5, 6] and applied by Takayasu, Oishi, Kubo [11, 12] to certain nonlinear two-point boundary value problems (see also Rump [7], Chapter 15), we provide a numerical method for verifying the existence of weak solutions of two-point boundary value problems of the form -u″ = a(x, u) + b(x, u)u‧, 0 b are functions that fulfill some regularity properties. The numerical approximation is done by cubic spline interpolation. Finally, the method is applied to the Duffing, the van der Pol and the Toda oscillator. The rigorous numerical computations were done with INTLAB [8].
Adaptation of a two-point boundary value problem solver to a vector-multiprocessor environment
Energy Technology Data Exchange (ETDEWEB)
Wright, S.J. (Mathematics Dept., North Carolina State Univ., Raleigh, NC (US)); Pereyra, V. (Weidlinger Associates, Los Angeles, CA (US))
1990-05-01
Systems of linear equations arising from finite-difference discretization of two-point boundary value problems have coefficient matrices that are sparse, with most or all of the nonzeros clustered in blocks near the main diagonal. Some efficiently vectorizable algorithms for factorizing these types of matrices and solving the corresponding linear systems are described. The relative effectiveness of the different algorithms varies according to the distribution of initial, final, and coupled end conditions. The techniques described can be extended to handle linear systems arising from other methods for two-point boundary value problems, such as multiple shooting and collocation. An application to seismic ray tracing is discussed.
Measurement and correlates of empathy among female Japanese physicians
Directory of Open Access Journals (Sweden)
Kataoka Hitomi U
2012-06-01
Full Text Available Abstract Background The measurement of empathy is important in the assessment of physician competence and patient outcomes. The prevailing view is that female physicians have higher empathy scores compared with male physicians. In Japan, the number of female physicians has increased rapidly in the past ten years. In this study, we focused on female Japanese physicians and addressed factors that were associated with their empathic engagement in patient care. Methods The Jefferson Scale of Empathy (JSE was translated into Japanese by using the back-translation procedure, and was administered to 285 female Japanese physicians. We designed this study to examine the psychometrics of the JSE and group differences among female Japanese physicians. Results The item-total score correlations of the JSE were all positive and statistically significant, ranging from .20 to .54, with a median of .41. The Cronbach’s coefficient alpha was .81. Female physicians who were practicing in “people-oriented” specialties obtained a significantly higher mean empathy score than their counterparts in “procedure-” or “technology-oriented” specialties. In addition, physicians who reported living with their parents in an extended family or living close to their parents, scored higher on the JSE than those who were living alone or in a nuclear family. Conclusions Our results provide support for the measurement property and reliability of the JSE in a sample of female Japanese physicians. The observed group differences associated with specialties and living arrangement may have implications for sustaining empathy. In addition, recognizing these factors that reinforce physicians’ empathy may help physicians to avoid career burnout.
Mattingly, S. W.; Berumen, J.; Chu, F.; Hood, R.; Skiff, F.
2013-11-01
A technique for probing velocity space correlations has been developed using laser-induced fluorescence. In this paper, a description of the experimental setup is given, with results to follow in a later publication. The experiment consists of a cylindrical plasma column 3 m long and radius ~ 0.25 cm, holding singly-charged argon ions (Ar II) with density n ~ 109 cm-3, Te ~ 5 eV, Ti,|| ~ .06 eV, and a 1 kG axial magnetic field. Two separate metastable lines are excited by single frequency lasers at 611 nm and 668 nm. These lasers may tune with a precision of .01 pm. The separate lasers are used to measure independent slices of the velocity distribution function. To confirm the velocity distribution and magnetic field, the Doppler-broadened, sigma-polarized Zeeman line for each transition is measured. With this, the absolute parallel component of ion velocity subject to LIF can be determined. The two separate lasers then give us a signal as a function of two separate parallel ion velocities. Two point correlation is used to reduce the noise floor on the plasma fluctuation. This fluctuation is then investigated as a function of the difference in velocity.
Holographic two-point functions for 4d log-gravity
Johansson, Niklas; Naseh, Ali; Zojer, Thomas
2012-01-01
We compute holographic one- and two-point functions of critical higher-curvature gravity in four dimensions. The two most important operators are the stress tensor and its logarithmic partner, sourced by ordinary massless and by logarithmic non-normalisable gravitons, respectively. In addition, the
Solvability for a Class of Abstract Two-Point Boundary Value Problems Derived from Optimal Control
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Wang Lianwen
2007-01-01
Full Text Available The solvability for a class of abstract two-point boundary value problems derived from optimal control is discussed. By homotopy technique existence and uniqueness results are established under some monotonic conditions. Several examples are given to illustrate the application of the obtained results.
Solvability for a Class of Abstract Two-Point Boundary Value Problems Derived from Optimal Control
Directory of Open Access Journals (Sweden)
Lianwen Wang
2008-01-01
Full Text Available The solvability for a class of abstract two-point boundary value problems derived from optimal control is discussed. By homotopy technique existence and uniqueness results are established under some monotonic conditions. Several examples are given to illustrate the application of the obtained results.
Modification of the Two-Point Touch Cane Technique: A Pilot Study.
Jacobson, William H.; Ehresman, Paul
1983-01-01
Four blind adults were observed to determine the extent of the natural movement of their centers of gravity in relation to arc height during the two-point touch technique for long cane travel. The Ss learned and practiced a modified technique using their center of gravity as much as possible. (Author)
A Measurement of the Galaxy Group-Thermal Sunyaev-Zel'dovich Effect Cross-Correlation Function
Vikram, Vinu; Lidz, Adam; Jain, Bhuvnesh
2016-12-01
Stacking cosmic microwave background (CMB) maps around known galaxy clusters and groups provides a powerful probe of the distribution of hot gas in these systems via the Sunyaev-Zel'dovich (SZ) effect. A stacking analysis allows one to detect the average SZ signal around low mass halos, to extend measurements out to large scales and measure the redshift-dependence of the SZ background. Motivated by these exciting prospects, we measure the two-point cross-correlation function between ˜380, 000 galaxy groups (at z = 0.01 - 0.2) from the Sloan Digital Sky Survey (SDSS) and Compton-y parameter maps constructed by the Planck collaboration. We find statistically significant correlations in each of six separate mass bins, with halo masses ranging from 1011.5 - 15.5M⊙/h. We compare with halo models of the SZ signal, which describe the stacked measurement in terms of one-halo and two-halo contributions. The one-halo term quantifies the average pressure profile around the groups in a mass bin, while the two-halo term describes the contribution of correlated neighbouring halos. For the massive groups we find clear evidence for the one- and two-halo regimes, while groups with mass below 1013M⊙/h are dominated by the two-halo term given the resolution of Planck data. We use the signal in the two-halo regime to determine the bias-weighted electron pressure of the universe: = 1.50 ± 0.226 × 10-7 keV cm-3 (1-σ) at z ≈ 0.15.
Stasyszyn, F; Dolag, K; Beck, R; Donnert, J
2010-01-01
Using cosmological MHD simulations of the magnetic field in galaxy clusters and filaments we evaluate the possibility to infer the magnetic field strength in filaments by measuring cross-correlation functions between Faraday Rotation Measures (RM) and the galaxy density field. We also test the reliability of recent estimates considering the problem of data quality and Galactic foreground (GF) removal in current datasets. Besides the two self-consistent simulations of cosmological magnetic fields based on primordial seed fields and galactic outflows analyzed here, we also explore a larger range of models scaling up the resulting magnetic fields of one of the simulations. We find that, if an unnormalized estimator for the cross-correlation functions and a GF removal procedure is used, the detectability of the cosmological signal is only possible for future instruments (e.g. SKA and ASKAP). However, mapping of the observed RM signal to the underlying magnetization of the Universe (both in space and time) is an e...
Someswara Rao, Chinta; Viswanadha Raju, S
2016-03-01
In this paper, we consider correlation coefficient, rank correlation coefficient and cosine similarity measures for evaluating similarity between Homo sapiens and monkeys. We used DNA chromosomes of genome wide genes to determine the correlation between the chromosomal content and evolutionary relationship. The similarity among the H. sapiens and monkeys is measured for a total of 210 chromosomes related to 10 species. The similarity measures of these different species show the relationship between the H. sapiens and monkey. This similarity will be helpful at theft identification, maternity identification, disease identification, etc.
Entropy measure of credit risk in highly correlated markets
Gottschalk, Sylvia
2017-07-01
We compare the single and multi-factor structural models of corporate default by calculating the Jeffreys-Kullback-Leibler divergence between their predicted default probabilities when asset correlations are either high or low. Single-factor structural models assume that the stochastic process driving the value of a firm is independent of that of other companies. A multi-factor structural model, on the contrary, is built on the assumption that a single firm's value follows a stochastic process correlated with that of other companies. Our main results show that the divergence between the two models increases in highly correlated, volatile, and large markets, but that it is closer to zero in small markets, when asset correlations are low and firms are highly leveraged. These findings suggest that during periods of financial instability, when asset volatility and correlations increase, one of the models misreports actual default risk.
Runge, Jakob
2013-01-01
The dependencies of the lagged (Pearson) correlation function on the coefficients of multivariate autoregressive models are interpreted in the framework of time series graphs. Time series graphs are related to the concept of Granger causality and encode the conditional independence structure of a multivariate process. The authors show that the complex dependencies of the Pearson correlation coefficient complicate an interpretation and propose a novel partial correlation measure with a straigh...
Hamaus, Nico; Desjacques, Vincent
2011-01-01
One of the main signatures of primordial non-Gaussianity of the local type is a scale-dependent correction to the bias of large-scale structure tracers such as galaxies or clusters, whose amplitude depends on the bias of the tracers itself. The dominant source of noise in the power spectrum of the tracers is caused by sampling variance on large scales (where the non-Gaussian signal is strongest) and shot noise arising from their discrete nature. Recent work has argued that one can avoid sampling variance by comparing multiple tracers of different bias, and suppress shot noise by optimally weighting halos of different mass. Here we combine these ideas and investigate how well the signatures of non-Gaussian fluctuations in the primordial potential can be extracted from the two-point correlations of halos and dark matter. On the basis of large $N$-body simulations with local non-Gaussian initial conditions and their halo catalogs we perform a Fisher matrix analysis of the two-point statistics. Compared to the st...
Geometric measures of quantum correlations with Bures and Hellinger distances
2016-01-01
Comment: to be published as a chapter of the book "Lectures on general quantum correlations and their applications" edited by F. Fanchini, D. Soares-Pinto, and G. Adesso (Springer, 2017); 43 pages, 3 figures
Measuring spin correlations in optical lattices using superlattice potentials
DEFF Research Database (Denmark)
Pedersen, Kim Georg Lind; Andersen, Brian Møller; Bruun, Georg Morten;
2011-01-01
We suggest two experimental methods for probing both short- and long-range spin correlations of atoms in optical lattices using superlattice potentials. The first method involves an adiabatic doubling of the periodicity of the underlying lattice to probe neighboring singlet (triplet) correlations...... for fermions (bosons) by the occupation of the resulting vibrational ground state. The second method utilizes a time-dependent superlattice potential to generate spin-dependent transport by any number of prescribed lattice sites, and probes correlations by the resulting number of doubly occupied sites....... For experimentally relevant parameters, we demonstrate how both methods yield large signatures of antiferromagnetic correlations of strongly repulsive fermionic atoms in a single shot of the experiment. Lastly, we show how this method may also be applied to probe d-wave pairing, a possible ground-state candidate...
Measurement of Angular Correlations in the Decay of Polarized Neutrons
DEFF Research Database (Denmark)
Christensen, Carl Jørgen; Krohn, V.E.; Ringo, G.R.
1970-01-01
The electron-momentum-neutron-spin correlation coefficient was found to be A=-0.115±0.008, and the antineutrino-momentum-neutron-spin correlation coefficient was found to be B=1.00±0.05. The value of A leads to |GA/GV|=1.26±0.02 for the ratio of Gamow-Teller-to-Fermi coupling constants in β decay...
NUMERICAL SIMULATION OF TWO-POINT CONTACT BETWEEN WHEEL AND RAIL
Institute of Scientific and Technical Information of China (English)
Jun Zhang; Shouguang Sun; Xuesong Jin
2009-01-01
The elastic-plastic contact problem with rolling friction of wheel-rail is solved using the FE parametric quadratic programming method. Thus, the complex elastic-plastic contact problem can be calculated with high accuracy and efficiency, while the Hertz's hypothesis and the elastic semi-space assumption are avoided. Based on the 'one-point' contact calculation of wheel-rail, the computational model of 'two-point' contact are established and calculated when the wheel flange is close to the rail. In the case of 'two-point' contact, the changing laws of wheelrail contact are introduced and contact forces in various load cases are carefully analyzed. The main reason of wheel flange wear and rail side wear is found. Lubrication computational model of the wheel flange is constructed. Comparing with the result without lubrication, the contact force between wheel flange and rail decreases, which is beneficial for reducing the wear of wheel-rail.
A NEW TWO-POINT ADAPTIVENONLINEAR APPROXIMATION METHOD FOR RELIABILITY ANALYSIS
Institute of Scientific and Technical Information of China (English)
LiuShutian
2004-01-01
A two-point adaptive nonlinear approximation (referred to as TANA4) suitable for reliability analysis is proposed. Transformed and normalized random variables in probabilistic analysis could become negative and pose a challenge to the earlier developed two-point approximations; thus a suitable method that can address this issue is needed. In the method proposed, the nonlinearity indices of intervening variables are limited to integers. Then, on the basis of the present method, an improved sequential approximation of the limit state surface for reliability analysis is presented. With the gradient projection method, the data points for the limit state surface approximation are selected on the original limit state surface, which effectively represents the nature of the original response function. On the basis of this new approximation, the reliability is estimated using a first-order second-moment method. Various examples, including both structural and non-structural ones, are presented to show the effectiveness of the method proposed.
Two-point functions of conformal primary operators in $\\mathcal{N}=1$ superconformal theories
Li, Daliang
2014-01-01
In $\\mathcal{N}=1$ superconformal theories in four dimensions the two-point function of superconformal multiplets is known up to an overall constant. A superconformal multiplet contains several conformal primary operators, whose two-point function coefficients can be determined in terms of the multiplet's quantum numbers. In this paper we work out these coefficients in full generality, i.e. for superconformal multiplets that belong to any irreducible representation of the Lorentz group with arbitrary scaling dimension and R-charge. From our results we recover the known unitarity bounds, and also find all shortening conditions, even for non-unitary theories. For the purposes of our computations we have developed a Mathematica package for the efficient handling of expansions in Grassmann variables.
State feedback control of surge oscillations of two-point mooring system
Mitra, R. K.; Banik, A. K.; Chatterjee, S.
2017-01-01
Stability analysis of surge oscillations of two-point mooring system under state feedback control with time-delay is investigated. The two-point mooring system is harmonically excited and essentially represents a strongly nonlinear Duffing oscillator. In this paper, a frequency domain based method viz. incremental harmonic balance method along with arc-length continuation technique (IHBC) is first employed to identify the primary and higher order subharmonic responses which may be present in such system. The IHBC is then reformulated in a manner to treat two-point mooring system under state feedback control with time-delay and is applied to obtain control of responses in an efficient and systematic way. The stability of uncontrolled responses for primary and higher order subharmonic oscillations is obtained by Floquet's theory using Hsu' scheme; whereas the stability of controlled responses is obtained by applying semi-discretization method for delay differential equation. The study focussed on the controlling primary, higher order subharmonics and chaotic responses by considering appropriate feedback gains and delay by way of (i) appreciable reduction of primary, subharmonic responses, (ii) exclusion of all higher order subharmonics 2T, 3T, 5T and 9T (1/n subharmonics or period-n solutions), and (iii) reduction of the extent of domain of all instability phenomena represented by various type of bifurcation of solutions, jump phenomena, chaotic responses etc. In the study, negative velocity feedback is observed to be much effective than state feedback for better controlling of surge oscillation of two-point mooring system. Also, the effect of larger gain values is investigated by an extensive parametric study for vibration control with different delay values.
Directory of Open Access Journals (Sweden)
Rana Majeed
2012-04-01
Full Text Available Abstract Background The zygoma plays an important role in the facial contour for both cosmetic and functional reasons; therefore zygomatic bone injuries should be properly diagnosed and adequately treated. Comparison of various surgical approaches and their complications can only be done objectively using outcome measurements which in turn require protocol management and long-term follow up. The preference for open reduction and internal fixation of zygomatic fractures at three points has continued to grow in response to observations of inadequate results from two point and one point fixation techniques. The objectives of this study were to compare the efficacy of zygomatic bone after treatment with ORIF using 2 point fixation and ORIF using 3 point fixation and compare the outcome of two procedures. Methods 100 patients were randomly divided equally into two groups. In group A, 50 patients were treated by ORIF using two point fixation by miniplates and in group B, 50 patients were treated by ORIF using three point fixation by miniplates. They were evaluated for their complications during and after surgery with their advantages and disadvantages and the difference between the two groups was observed. Results A total of 100 fractures were sustained. We found that postoperative complication like decreased malar height and vertical dystopia was more common in those patients who were treated by two point fixation than those who were treated with three point fixation. Conclusions Based on this study open reduction and internal fixation using three point fixation by miniplates is the best available method for the treatment zygomatic bone fractures.
A rapid and accurate two-point ray tracing method in horizontally layered velocity model
Institute of Scientific and Technical Information of China (English)
TIAN Yue; CHEN Xiao-fei
2005-01-01
A rapid and accurate method for two-point ray tracing in horizontally layered velocity model is presented in this paper. Numerical experiments show that this method provides stable and rapid convergence with high accuracies, regardless of various 1-D velocity structures, takeoff angles and epicentral distances. This two-point ray tracing method is compared with the pseudobending technique and the method advanced by Kim and Baag (2002). It turns out that the method in this paper is much more efficient and accurate than the pseudobending technique, but is only applicable to 1-D velocity model. Kim(s method is equivalent to ours for cases without large takeoff angles, but it fails to work when the takeoff angle is close to 90o. On the other hand, the method presented in this paper is applicable to cases with any takeoff angles with rapid and accurate convergence. Therefore, this method is a good choice for two-point ray tracing problems in horizontally layered velocity model and is efficient enough to be applied to a wide range of seismic problems.
Calculating two-point resistances in distance-regular resistor networks
Energy Technology Data Exchange (ETDEWEB)
Jafarizadeh, M A [Department of Theoretical Physics and Astrophysics, University of Tabriz, Tabriz 51664 (Iran, Islamic Republic of); Sufiani, R [Department of Theoretical Physics and Astrophysics, University of Tabriz, Tabriz 51664 (Iran, Islamic Republic of); Jafarizadeh, S [Department of Electrical and computer engineering, University of Tabriz, Tabriz 51664 (Iran, Islamic Republic of)
2007-05-11
An algorithm for the calculation of the resistance between two arbitrary nodes in an arbitrary distance-regular resistor network is provided, where the calculation is based on stratification introduced in Jafarizadeh and Salimi (2006 J. Phys. A: Math. Gen. 39 1-29) and the Stieltjes transform of the spectral distribution (Stieltjes function) associated with the network. It is shown that the resistances between a node {alpha} and all nodes {beta} belonging to the same stratum with respect to the {alpha} (R{sub {alpha}}{sub {beta}{sup (i)}}), {beta} belonging to the ith stratum with respect to the {alpha}) are the same. Also, the analytical formulae for two-point resistances R{sub {alpha}}{sub {beta}{sup (i)}}, i=1,2,3, are given in terms of the size of the network and corresponding intersection numbers. In particular, the two-point resistances in a strongly regular network are given in terms of its parameters (v, {kappa}, {lambda}, {mu}). Moreover, the lower and upper bounds for two-point resistances in strongly regular networks are discussed.
Measuring weak lensing correlations of Type Ia Supernovae
Scovacricchi, D; Macaulay, E; Bacon, D
2016-01-01
We study the feasibility of detecting weak lensing spatial correlations between Supernova (SN) Type Ia magnitudes with present (Dark Energy Survey, DES) and future (Large Synoptic Survey Telescope, LSST) surveys. We investigate the angular auto-correlation function of SN magnitudes (once the background cosmology has been subtracted) and cross-correlation with galaxy catalogues. We examine both analytical and numerical predictions, the latter using simulated galaxy catalogues from the MICE Grand Challenge Simulation. We predict that we will be unable to detect the SN auto-correlation in DES, while it should be detectable with the LSST SN deep fields (15,000 SNe on 70 deg^2) at ~6sigma level of confidence (assuming 0.15 magnitudes of intrinsic dispersion). The SN-galaxy cross-correlation function will deliver much higher signal-to-noise, being detectable in both surveys with an integrated signal-to-noise of ~100 (up to 30 arcmin separations). We predict joint constraints on the matter density parameter (Omega_m...
Measures of galaxy environment -- II. Rank-ordered mark correlations
Skibba, Ramin A; Croton, Darren J; Muldrew, Stuart I; Abbas, Ummi; Pearce, Frazer R; Shattow, Genevieve M
2012-01-01
We analyze environmental correlations using mark clustering statistics with the mock galaxy catalogue constructed by Muldrew et al. (Paper I). We find that mark correlation functions are able to detect even a small dependence of galaxy properties on the environment, quantified by the overdensity $1+\\delta$, while such a small dependence would be difficult to detect by traditional methods. We then show that rank ordering the marks and using the rank as a weight is a simple way of comparing the correlation signals for different marks. With this we quantify to what extent fixed-aperture overdensities are sensitive to large-scale halo environments, nearest-neighbor overdensities are sensitive to small-scale environments within haloes, and colour is a better tracer of overdensity than is luminosity.
Eddy correlation measurements of oxygen uptake in deep ocean sediments
DEFF Research Database (Denmark)
Berg, P.; Glud, Ronnie Nøhr; Hume, A.
2010-01-01
Abstract: We present and compare small sediment-water fluxes of O-2 determined with the eddy correlation technique, with in situ chambers, and from vertical sediment microprofiles at a 1450 m deep-ocean site in Sagami Bay, Japan. The average O-2 uptake for the three approaches, respectively, was ...
Benefits of Time Correlation Measurements for Passive Screening
Murer, David; Blackie, Douglas; Peerani, Paolo
2014-02-01
The “FLASH Portals Project” is a collaboration between Arktis Radiation Detectors Ltd (CH), the Atomic Weapons Establishment (UK), and the Joint Research Centre (European Commission), supported by the Technical Support Working Group (TSWG). The program's goal was to develop and demonstrate a technology to detect shielded special nuclear materials (SNM) more efficiently and less ambiguously by exploiting time correlation. This study presents experimental results of a two-sided portal monitor equipped with in total 16 4He fast neutron detectors as well as four polyvinyltoluene (PVT) plastic scintillators. All detectors have been synchronized to nanosecond precision, thereby allowing the resolution of time correlations from timescales of tens of microseconds (such as (n, γ) reactions) down to prompt fission correlations directly. Our results demonstrate that such correlations can be detected in a typical radiation portal monitor (RPM) geometry and within operationally acceptable time scales, and that exploiting these signatures significantly improves the performance of the RPM compared to neutron counting. Furthermore, the results show that some time structure remains even in the presence of heavy shielding, thus significantly improving the sensitivity of the detection system to shielded SNM.
Fission fragment energy correlation measurements for Cf-252(SF)
Energy Technology Data Exchange (ETDEWEB)
Barreau, G.; Sicre, A.; Caitucoli, F.; Doan, T.P.; Leroux, B.; Martinez, G.; Asghar, M.; Benfoughal, T.
1986-01-01
The mean total kinetic energy, its variance and to a lesser extent the mass yield show strong and correlated fluctuations. These structures are discussed in terms of the static macro-microscopic potential energy calculations. The cold fission mass yield distribution exhibits a fine structure which results from an odd-even effect on nuclear charge.
Measuring Two-Event Structural Correlations on Graphs
2012-08-01
Morgan Kaufmann , 2006. [13] T. Hesterberg. Weighted average importance sampling and defensive mixture distributions. Technometrics, 37(2):185–194, 1995...15] M. Kendall and J. Gibbons. Rank correlation methods. Edward Arnold , 1990. [16] A. Khan, X. Yan, and K. Wu. Towards proximity pattern mining in
Correlation measure to detect time series distances, whence economy globalization
Miśkiewicz, Janusz; Ausloos, Marcel
2008-11-01
An instantaneous time series distance is defined through the equal time correlation coefficient. The idea is applied to the Gross Domestic Product (GDP) yearly increments of 21 rich countries between 1950 and 2005 in order to test the process of economic globalisation. Some data discussion is first presented to decide what (EKS, GK, or derived) GDP series should be studied. Distances are then calculated from the correlation coefficient values between pairs of series. The role of time averaging of the distances over finite size windows is discussed. Three network structures are next constructed based on the hierarchy of distances. It is shown that the mean distance between the most developed countries on several networks actually decreases in time, -which we consider as a proof of globalization. An empirical law is found for the evolution after 1990, similar to that found in flux creep. The optimal observation time window size is found ≃15 years.
Kaneko, Atsushi; Asai, Noriyoshi; Kanda, Tadashi
2005-01-01
The purpose of the present study was to determine the effect of age on digital pressure perception as measured by two-point discrimination (2PD) testing. The subjects were 177 normal volunteers ranging in age from 20 to 79 years. Perceptible pressure of static and moving 2PD was measured on the index finger and little finger, using the Pressure-specifying Sensory Device. The threshold of pressure perception increased significantly with advancing age in both static and moving 2PD tests. There was a marked increase in subjects older than 60 years. Pressure perception was significantly higher for static 2PD than for moving 2PD in subjects 70-79 years of age. The threshold of pressure perception for static and moving 2PD gradually increased with advancing age, and was markedly elevated in subjects older than 60 years.
BENEFITS OF TIME CORRELATION MEASUREMENTS FOR PASSIVE SCREENING
2014-01-01
The “FLASH Portals Project” is a collaboration between Arktis Radiation Detectors Ltd (CH), the Atomic Weapons Establishment (UK), and the Joint Research Centre (European Commission), supported by the Technical Support Working Group (TSWG). The program’s goal was to develop and demonstrate a technology to detect shielded special nuclear materials (SNM) more efficiently and less ambiguously by exploiting time correlation. This study presents experimental results of a two-sided portal monitor e...
Parallax Measurement Using an Image Matched Filter Correlator
1975-04-01
was also necessary to isolate the laser by installing rubber pads under it and by suspending the umbilical cord in order to eliminate vibrations...mirror. This assembly tended to vibrate and it proved necessary to remove it and replace the small mirror by a larger mirror clamped directly to...where a ^ b. Consider the situation in Figure A-l where a hologram is re- corded in plane H. The correlations are formed by lens Lj in
A new measure-correlate-predict approach for resource assessment
Energy Technology Data Exchange (ETDEWEB)
Joensen, A.; Landberg, L. [Risoe National Lab., Dept. of Wind Energy and Atmospheric Physics, Roskilde (Denmark); Madsen, H. [The Technical Univ. of Denmark, Dept. of Mathematical Modelling, Lyngby (Denmark)
1999-03-01
In order to find reasonable candidate site for wind farms, it is of great importance to be able to calculate the wind resource at potential sites. One way to solve this problem is to measure wind speed and direction at the site, and use these measurements to predict the resource. If the measurements at the potential site cover less than e.g. one year, which most likely will be the case, it is not possible to get a reliable estimate of the long-term resource, using this approach. If long-term measurements from e.g. some nearby meteorological station are available, however, then statistical methods can be used to find a relation between the measurements at the site and at the meteorological station. This relation can then be used to transform the long-term measurements to the potential site, and the resource can be calculated using the transformed measurements. Here, a varying-coefficient model, estimated using local regression, is applied in order to establish a relation between the measurements. The approach is evaluated using measurements from two sites, located approximately two kilometres apart, and the results show that the resource in this case can be predicted accurately, although this approach has serious shortcomings. (au)
Covariant and infrared-free graviton two-point function in de Sitter spacetime. II.
Pejhan, Hamed; Rahbardehghan, Surena
2016-11-01
The solution to the linearized Einstein equation in de Sitter (dS) spacetime and the corresponding two-point function are explicitly written down in a gauge with two parameters "a " and "b ". The quantization procedure, independent of the choice of the coordinate system, is based on a rigorous group theoretical approach. Our result takes the form of a universal spin-two (transverse-traceless) sector and a gauge-dependent spin-zero (pure-trace) sector. Scalar equations are derived for the structure functions of each part. We show that the spin-two sector can be written as the resulting action of a second-order differential operator (the spin-two projector) on a massless minimally coupled scalar field (the spin-two structure function). The operator plays the role of a symmetric rank-2 polarization tensor and has a spacetime dependence. The calculated spin-two projector grows logarithmically with distance and also no dS-invariant solution for either structure functions exist. We show that the logarithmically growing part and the dS-breaking contribution to the spin-zero part can be dropped out, respectively, for suitable choices of parameters "a " and "b ". Considering the transverse-traceless graviton two-point function, however, shows that dS breaking is universal (cannot be gauged away). More exactly, if one wants to respect the covariance and positiveness conditions, the quantization of the dS graviton field (as for any gauge field) cannot be carried out directly in a Hilbert space and involves unphysical negative norm states. However, a suitable adaptation (Krein spaces) of the Gupta-Bleuler scheme for massless fields, based on the group theoretical approach, enables us to obtain the corresponding two-point function satisfying the conditions of locality, covariance, transversality, index symmetrizer, and tracelessness.
Directory of Open Access Journals (Sweden)
Natalia A Iutaka
2017-01-01
Conclusion: VFI showed a strong correlation with MD and PSD but demonstrated a weak correlation with structural measures. It can possibly be used as a marker for functional impairment severity in patients with glaucoma.
Covalent docking using autodock: Two-point attractor and flexible side chain methods.
Bianco, Giulia; Forli, Stefano; Goodsell, David S; Olson, Arthur J
2016-01-01
We describe two methods of automated covalent docking using Autodock4: the two-point attractor method and the flexible side chain method. Both methods were applied to a training set of 20 diverse protein-ligand covalent complexes, evaluating their reliability in predicting the crystallographic pose of the ligands. The flexible side chain method performed best, recovering the pose in 75% of cases, with failures for the largest inhibitors tested. Both methods are freely available at the AutoDock website (http://autodock.scripps.edu). © 2015 The Protein Society.
Two-point Functions at Two Loops in Three Flavour Chiral Perturbation Theory
Amorós, G; Talavera, P; Amoros, Gabriel; Bijnens, Johan; Talavera, Pere
2000-01-01
The vector and axial-vector two-point functions are calculated to next-to-next-to-leading order in Chiral Perturbation Theory for three light flavours. We also obtain expressions at the same order for the masses, $m_\\pi^2$, $m_K^2$ and $m_\\eta^2$, and the decay constants, $F_\\pi$, $F_K$ and $F_\\eta$. We present some numerical results after a simple resonance estimate of some of the new ${\\cal O}(p^6)$ constants.
Electrical conductivity measurements of nanofluids and development of new correlations.
Konakanchi, Hanumantharao; Vajjha, Ravikanth; Misra, Debasmita; Das, Debendra
2011-08-01
In this study the electrical conductivity of aluminum oxide (Al2O3), silicon dioxide (SiO2) and zinc oxide (ZnO) nanoparticles dispersed in propylene glycol and water mixture were measured in the temperature range of 0 degrees C to 90 degrees C. The volumetric concentration of nanoparticles in these fluids ranged from 0 to 10% for different nanofluids. The particle sizes considered were from 20 nm to 70 nm. The electrical conductivity measuring apparatus and the measurement procedure were validated by measuring the electrical conductivity of a calibration fluid, whose properties are known accurately. The measured electrical conductivity values agreed within +/- 1% with the published data reported by the manufacturer. Following the validation, the electrical conductivities of different nanofluids were measured. The measurements showed that electrical conductivity of nanofluids increased with an increase in temperature and also with an increase in particle volumetric concentration. For the same nanofluid at a fixed volumetric concentration, the electrical conductivity was found to be higher for smaller particle sizes. From the experimental data, empirical models were developed for three nanofluids to express the electrical conductivity as functions of temperature, volumetric concentration and the size of the nanoparticles.
Physical meaning of two-particle HBT measurements in case of correlated emission
Bialas, A.; Zalewski, K.
2004-01-01
It is shown that, in the presence of correlations in particle emission, the measured HBT radii are related to the correlation range rather than to the size of the interaction volume. Only in the case of weak correlations the standard interpretation may be applicable, The earlier discussion [1] of short-range correlations in configuration space is generalized to include also the correlations of particle momenta.
Accurate measurement of curvilinear shapes by Virtual Image Correlation
Semin, B; Auradou, H.; François, M.L.M.
2011-01-01
Abstract The proposed method allows the detection and the measurement, in the sense of metrology, of smooth elongated curvilinear shapes. Such measurements are required in many fields of physics, for example: mechanical engineering, biology or medicine (deflection of beams, fibers or filaments), fluid mechanics or chemistry (detection of fronts). Contrary to actual methods, the result is given in an analytical form of class C? (and not a finite set of locations or pixels) thus curv...
Electrophysiological correlates of listening effort: neurodynamical modeling and measurement.
Strauss, Daniel J; Corona-Strauss, Farah I; Trenado, Carlos; Bernarding, Corinna; Reith, Wolfgang; Latzel, Matthias; Froehlich, Matthias
2010-06-01
An increased listing effort represents a major problem in humans with hearing impairment. Neurodiagnostic methods for an objective listening effort estimation might support hearing instrument fitting procedures. However the cognitive neurodynamics of listening effort is far from being understood and its neural correlates have not been identified yet. In this paper we analyze the cognitive neurodynamics of listening effort by using methods of forward neurophysical modeling and time-scale electroencephalographic neurodiagnostics. In particular, we present a forward neurophysical model for auditory late responses (ALRs) as large-scale listening effort correlates. Here endogenously driven top-down projections related to listening effort are mapped to corticothalamic feedback pathways which were analyzed for the selective attention neurodynamics before. We show that this model represents well the time-scale phase stability analysis of experimental electroencephalographic data from auditory discrimination paradigms. It is concluded that the proposed neurophysical and neuropsychological framework is appropriate for the analysis of listening effort and might help to develop objective electroencephalographic methods for its estimation in future.
Correlation measurements of light transmittance in polymer dispersed liquid crystals
Maksimyak, P. P.; Nehrych, A. L.
2015-11-01
The methods of correlation optics are for the first time applied to study structure of liquid crystal (LC) - polymer (P) composites at various concentrations of LC and P. Their phase correlation function (PCF) was obtained considering LC-P composite as a random phase screen. The amplitude of PCF contains information about number of LC domains and structure of LC director inside of them, while a half-width of this function is connected with a size of these domains. We studied unpowered and powered composite layers with a thickness of 5 μm. As liquid crystal and polymer were used nematic LC E7 from Merck and photopolymer composition NOA65 from Norland. Concentration of polymer φP was varied in a range 10-55 vol. %. In good agreement with previous studies by SEM technique we detected monotone decrease of LC domains with concentration of polymer. With application of electric field, amplitude of PCF behaves differently for the samples with different polymer content. For the samples with φP>35 vol. % (samples having morphology of polymer dispersed LC), this dependence is monotonic. In turn, if φPLC morphology), the amplitude of PCF non-monotonically depends on the applied voltage going through a maximum. The latter fact is explained by transformation of orientational defects of LC phase with the applied voltage.
Solving Directly Two Point Non Linear Boundary Value Problems Using Direct Adams Moulton Method
Directory of Open Access Journals (Sweden)
Zanariah A. Majid
2011-01-01
Full Text Available Problem statement: In this study, a direct method of Adams Moulton type was developed for solving non linear two point Boundary Value Problems (BVPs directly. Most of the existence researches involving BVPs will reduced the problem to a system of first order Ordinary Differential Equations (ODEs. This approach is very well established but it obviously will enlarge the systems of first order equations. However, the direct method in this research will solved the second order BVPs directly without reducing it to first order ODEs. Approach: Lagrange interpolation polynomial was applied in the derivation of the proposed method. The method was implemented using constant step size via shooting technique in order to determine the approximated solutions. The shooting technique will employ the Newtons method for checking the convergent of the guessing values for the next iteration. Results: Numerical results confirmed that the direct method gave better accuracy and converged faster compared to the existing method. Conclusion: The proposed direct method is suitable for solving two point non linear boundary value problems.
Symplectic invariants, entropic measures and correlations of Gaussian states
Energy Technology Data Exchange (ETDEWEB)
Serafini, Alessio; Illuminati, Fabrizio; Siena, Silvio De [Dipartimento di Fisica ' E R Caianiello' , Universita di Salerno, INFM UdR Salerno, INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S Allende, 84081 Baronissi, SA (Italy)
2004-01-28
We present a derivation of the Von Neumann entropy and mutual information of arbitrary two-mode Gaussian states, based on the explicit determination of the symplectic eigenvalues of a generic covariance matrix. The key role of the symplectic invariants in such a determination is pointed out. We show that the Von Neumann entropy depends on two symplectic invariants, while the purity (or the linear entropy) is determined by only one invariant, so that the two quantities provide two different hierarchies of mixed Gaussian states. A comparison between mutual information and entanglement of formation for symmetric states is considered, taking note of the crucial role of the symplectic eigenvalues in qualifying and quantifying the correlations present in a generic state. (letter to the editor)
Toelle, V D; Robison, O W
1985-01-01
Data from 528 male and 645 female progeny of 63 sires were used to estimate genetic correlations between female and male reproductive traits. Data were from two Hereford herds involved in a long-term selection program of the North Carolina Agricultural Experiment Service. Testicular measurements of circumference, diameter, length and volume were obtained on bulls at 205 and 365 d. Testicular growth measures were defined as differences between 205-and 365-d measurements. Heifers were placed in the breeding herd as yearlings and given two breeding seasons to produce a calf. Traits utilized from females were three age-at-first-breeding traits, two age-at-first-calving traits, two pregnancy rate traits, rebreeding interval and calving interval. Genetic correlations were estimated from half-sib and from sire-daughter analyses. Seventy-five percent or more of the correlations of testicular measurements with pregnancy rats, age at first breeding and age at first calving were in the favorable direction. Average correlations were .62, -.55 and -.66, respectively. For each of the remaining female traits, approximately 50% of the correlations were favorable and the average correlations were small. Correlations were summarized by testicular measurement with favorable correlations given a negative sign. Testicular diameter had more favorable correlations (80%) than length, volume or circumference (70%). However, average correlations were similar (-.31, -.30, -.34 and -.26, respectively). Testicular measurements taken at either 205 or 365 d had the same percentage of favorable correlations (72%), while testicular growth measurements had a slightly higher percentage of favorable correlations (78%). Average correlations of 365-d measures were higher (-.38) than either 205-d or growth measures (-.25 and -.28, respectively). Heritabilities for testicular measurements tended to be moderate to high, while those for female reproduction tended to be low to moderate. These results
Xue, Zhenyu; Vlachos, Pavlos P
2014-01-01
In particle image velocimetry (PIV) the measurement signal is contained in the recorded intensity of the particle image pattern superimposed on a variety of noise sources. The signal-to-noise-ratio (SNR) strength governs the resulting PIV cross correlation and ultimately the accuracy and uncertainty of the resulting PIV measurement. Hence we posit that correlation SNR metrics calculated from the correlation plane can be used to quantify the quality of the correlation and the resulting uncertainty of an individual measurement. In this paper we present a framework for evaluating the correlation SNR using a set of different metrics, which in turn are used to develop models for uncertainty estimation. The SNR metrics and corresponding models presented herein are expanded to be applicable to both standard and filtered correlations. In addition, the notion of a valid measurement is redefined with respect to the correlation peak width in order to be consistent with uncertainty quantification principles and distinct ...
GHz measurements of correlated electron systems in high magnetic fields
Edwards, R S
2002-01-01
This Thesis presents experiments performed on the high-frequency conductivity of materials in high magnetic fields. The angle dependence of resonances measured in the millimetre-wave absorption is studied using a rotating resonant cavity system, and the frequency dependence is measured using transmission techniques and a tuneable resonant cavity. Chapter 1 introduces the materials. These include the crystalline organic metals, the layered superconductor Sr sub 2 RUO sub 4 and the quantum Ising ferromagnet LiHoF sub 4. In Chapters 2 and 3, the necessary physics and experimental techniques for their investigation are outlined. Chapters 4 to 6 present measurements of cyclotron resonance in layered materials. Chapter 4 describes several models for the origin of cyclotron resonance harmonics, and describes the first definite measurement of the harmonics of a cyclotron resonance in an organic molecular metal, namely beta sup - (BEDT-TTF) sub 2 SF sub 5 CH sub 2 CF sub 2 SO sub 3. The angle dependence of the field p...
Correlation between precision gravity and subsidence measurements at Cerro Prieto
Energy Technology Data Exchange (ETDEWEB)
Zelwer, R.; Grannell, R.B.
1982-10-01
Precision gravity measurements were made in the region of the Cerro Prieto geothermal field at yearly intervals from 1977 to 1981 to assess the feasibility of using gravity to determine subsurface reservoir changes with time. The extent of mass recharge in response to the continued production of fluids from this field was studied. Changes in gravity and ground elevation were observed throughout the region for the period of observation. Results indicate that the largest changes observed were the result of the Magnitude 6.1 (Caltech) Victoria earthquake of 8 June 1980. The epicenter of this earthquake was located 25 km southeast of the field on the Cerro Prieto Fault, which bounds the field on the southwest. Subsidence of up to 55 cm was measured east of the power plant, in the region between the northern end of the Cerro Prieto Fault and the southern end of the Imperial Fault. This area has been postulated to be the site of an active spreading center or pull-apart basin, and has been characterized by a high level of seismic activity during the last 10 years. Minor subsidence and small related gravity changes for the period preceeding the Victoria earthquake suggest that in spite of large fluid production rates, the reservoir is being almost completely recharged and that a measurable increase in subsurface density may be taking place. The results of measurements of horizontal ground motions made in this area are discussed in relation to the gravity and subsidence observations.
Hoessel, Peter; Riemann, Solveig; Knebl, Robert; Schroeder, Jens; Schuh, Gerd; Castillo, Catalina
2010-01-01
A new two-point bending stiffness method on flat hair strands was developed and validated after application of hair styling gels and hair styling sprays. A special mold was used to align single hair fibers after applying the formulations to the hair. The styling gels used contain different commercially available thickeners and styling polymers, e.g., carbomer, acrylates/beheneth-25 methacrylate copolymer, Polyquaternium-86, PVP, VP/VA copolymers, and VP/methacrylamide/vinylimidazole copolymer. Evaluation of hair sprays was performed after spray application on flat hair strands. Commercially available hair styling resins were used, e.g. acrylates/t-butylacrylamide copolymer, octylacrylamide/acrylates/butylaminoethyl methacrylate copolymer, and VP/VA copolymer (30:70). The new stiffness test method provided the best correlation with practically relevant sensory assessments on hair strands and a panel test in which styling gels were evaluated. However, we did not observe a correlation between the new stiffness method on flat hair strands and practical assessments in hair spray application. We postulate that different polymer/hair composites are responsible for these discrepancies. Hairs on model heads for half-side testing are spot-welded after spray application, while hairs are seam-welded in the stiffness test after alignment of single hair fibers. This alignment is necessary to achieve reproducible results.
Correlation of subjective and objective measures of speech intelligibility
Bowden, Erica E.; Wang, Lily M.; Palahanska, Milena S.
2003-10-01
Currently there are a number of objective evaluation methods used to quantify the speech intelligibility in a built environment, including the Speech Transmission Index (STI), Rapid Speech Transmission Index (RASTI), Articulation Index (AI), and the Percentage Articulation Loss of Consonants (%ALcons). Many of these have been used for years; however, questions remain about their accuracy in predicting the acoustics of a space. Current widely used software programs can quickly evaluate STI, RASTI, and %ALcons from a measured impulse response. This project compares subjective human performance on modified rhyme and phonetically balanced word tests with objective results calculated from impulse response measurements in four different spaces. The results of these tests aid in understanding performance of various methods of speech intelligibility evaluation. [Work supported by the Univ. of Nebraska Center for Building Integration.] For Speech Communication Best Student Paper Award.
The Belt voice: Acoustical measurements and esthetic correlates
Bounous, Barry Urban
This dissertation explores the esthetic attributes of the Belt voice through spectral acoustical analysis. The process of understanding the nature and safe practice of Belt is just beginning, whereas the understanding of classical singing is well established. The unique nature of the Belt sound provides difficulties for voice teachers attempting to evaluate the quality and appropriateness of a particular sound or performance. This study attempts to provide answers to the question "does Belt conform to a set of measurable esthetic standards?" In answering this question, this paper expands on a previous study of the esthetic attributes of the classical baritone voice (see "Vocal Beauty", NATS Journal 51,1) which also drew some tentative conclusions about the Belt voice but which had an inadequate sample pool of subjects from which to draw. Further, this study demonstrates that it is possible to scientifically investigate the realm of musical esthetics in the singing voice. It is possible to go beyond the "a trained voice compared to an untrained voice" paradigm when evaluating quantitative vocal parameters and actually investigate what truly beautiful voices do. There are functions of sound energy (measured in dB) transference which may affect the nervous system in predictable ways and which can be measured and associated with esthetics. This study does not show consistency in measurements for absolute beauty (taste) even among belt teachers and researchers but does show some markers with varying degrees of importance which may point to a difference between our cognitive learned response to singing and our emotional, more visceral response to sounds. The markers which are significant in determining vocal beauty are: (1) Vibrancy-Characteristics of vibrato including speed, width, and consistency (low variability). (2) Spectral makeup-Ratio of partial strength above the fundamental to the fundamental. (3) Activity of the voice-The quantity of energy being produced. (4
This study aimed to explore the associations among psychological correlates and physical activity (PA) in Chinese children and to further examine whether these associations varied by different PA measures. PA self-efficacy, motivation, and preference were reported in 449 8–13-year-old Chinese childr...
Measurement of Genuine Three-Particle Bose-Einstein Correlations in Hadronic Z decay
Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, Michael; Doria, A; Dova, M T; Duchesneau, D; Echenard, B; Eline, A; El-Mamouni, H; Engler, A; Eppling, F J; Ewers, A; Extermann, Pierre; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hakobyan, R S; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Palomares, C; Pandoulas, D; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, B; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R P; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wallraff, W; Wang, X L; Wang, Z M; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M
2002-01-01
We measure three-particle Bose-Einstein correlations in hadronic Z decay with the L3 detector at LEP. Genuine three-particle Bose-Einstein correlations are observed. By comparing two- and three-particle correlations we find that the data are consistent with fully incoherent pion production.
Imaging of adult flatfoot: correlation of radiographic measurements with MRI.
Lin, Yu-Ching; Mhuircheartaigh, Jennifer Ni; Lamb, Joshua; Kung, Justin W; Yablon, Corrie M; Wu, Jim S
2015-02-01
OBJECTIVE. The purpose of this study is to determine whether radiographic foot measurements can predict injury of the posterior tibial tendon (PTT) and the supporting structures of the medial longitudinal arch as diagnosed on MRI. MATERIALS AND METHODS. After institutional review board approval, 100 consecutive patients with radiographic and MRI examinations performed within a 2-month period were enrolled. Thirty-one patients had PTT dysfunction clinically, and 69 patients had other causes of ankle pain. Talonavicular uncoverage angle, incongruency angle, calcaneal pitch angle, Meary angle, cuneiform-to-fifth metatarsal height, and talar tilt were calculated on standing foot or ankle radiographs. MRI was used to assess for abnormalities of the PTT (tenosynovitis, tendinosis, and tear) and supporting structures of the medial longitudinal arch (spring ligament, deltoid ligament, and sinus tarsi). Statistical analysis was performed using the chi-square and Fisher exact tests for categoric variables; the Student t test was used for continuous variables. RESULTS. There was a statistically significant association of PTT tear with abnormal talonavicular uncoverage angle, calcaneal pitch angle, Meary angle, and cuneiform-to-fifth metatarsal height. PTT tendinosis and isolated tenosynovitis had a poor association with most radiologic measurements. If both calcaneal pitch and Meary angles were normal, no PTT tear was present. An abnormal calcaneal pitch angle had the best association with injury to the supporting medial longitudinal arch structures. CONCLUSION. Radiographic measurements, especially calcaneal pitch and Meary angles, can be useful in detecting PTT tears. Calcaneal pitch angle provides the best assessment of injury to the supporting structures of the medial longitudinal arch.
Inverted catenoid as a fluid membrane with two points pulled together.
Castro-Villarreal, Pavel; Guven, Jemal
2007-07-01
Under inversion in any (interior) point, a catenoid transforms into a deflated compact geometry which touches at two points (its poles). The catenoid is a minimal surface and, as such, is an equilibrium shape of a symmetric fluid membrane. The conformal symmetry of the Hamiltonian implies that inverted minimal surfaces are also equilibrium shapes. However, they will exhibit curvature singularities at their poles. Such singularities are the geometrical signature of the external forces required to pull the poles together. These forces will set up stresses in the inverted shapes. Tuning the force corresponds geometrically to the translation of the point of inversion. For any fixed surface area, there will be a maximum force. The associated shape is a symmetric discocyte. Lowering the external force will induce a transition from the discocyte to a cup-shaped stomatocyte.
Roul, Pradip
2016-06-01
This paper presents a new iterative technique for solving nonlinear singular two-point boundary value problems with Neumann and Robin boundary conditions. The method is based on the homotopy perturbation method and the integral equation formalism in which a recursive scheme is established for the components of the approximate series solution. This method does not involve solution of a sequence of nonlinear algebraic or transcendental equations for the unknown coefficients as in some other iterative techniques developed for singular boundary value problems. The convergence result for the proposed method is established in the paper. The method is illustrated by four numerical examples, two of which have physical significance: The first problem is an application of the reaction-diffusion process in a porous spherical catalyst and the second problem arises in the study of steady-state oxygen-diffusion in a spherical cell with Michaelis-Menten uptake kinetics.
A High Performance Spread Spectrum Clock Generator Using Two-Point Modulation Scheme
Kao, Yao-Huang; Hsieh, Yi-Bin
A new spread spectrum clock generator (SSCG) using two-point delta-sigma modulation is presented in this paper. Not only the divider is varied, but also the voltage controlled oscillator is modulated. This technique can enhance the modulation bandwidth so that the effect of EMI suppression is improved with lower order ΣΔ modulator and can simultaneously optimize the jitter and the modulation profile. In addition, the method of two-path is applied to the loop filter to reduce the capacitance value such that the total integration can be achieved. The proposed SSCG has been fabricated in a 0.35μm CMOS process. The clock of 400MHz with center spread ratios of 1.25% and 2.5% are verified. The peak EMI reduction is 19.73dB for the case of 2.5%. The size of chip area is 0.90×0.89mm2.
Two-point gauge invariant quark Green's functions with polygonal phase factor lines
Sazdjian, H
2013-01-01
Polygonal lines are used for the paths of the gluon field phase factors entering in the definition of gauge invariant quark Green's functions. This allows classification of the Green's functions according to the number of segments the polygonal lines contain. Functional relations are established between Green's functions with polygonal lines with different numbers of segments. An integrodifferential equation is obtained for the quark two-point Green's function with a path along a single straight line segment where the kernels are represented by a series of Wilson loop averages along polygonal contours. The equation is exactly and analytically solved in the case of two-dimensional QCD in the large-$N_c$ limit. The solution displays generation of an infinite number of dynamical quark masses accompanied with branch point singularities that are stronger than simple poles. An approximation scheme, based on the counting of functional derivatives of Wilson loops, is proposed for the resolution of the equation in fou...
Applying inversion to construct planar, rational spirals that satisfy two-point G(2) Hermite data
Kurnosenko, A
2010-01-01
A method of two-point G(2) Hermite interpolation with spirals is proposed. To construct a sought for curve, the inversion is applied to an arc of some other spiral. To illustrate the method, inversions of parabola are considered in detail. The resulting curve is 4th degree rational. The method allows the matching of a wide range of boundary conditions, including those which require an inflection. Although not all G(2) Hermite data can be matched with a spiral generated from a parabolic arc, introducing one intermediate G(2) data solves the problem. Expanding the method by involving other spirals arcs is also discussed. (C) 2009 Elsevier B.V. All rights reserved.
Two-point resistance of a resistor network embedded on a globe.
Tan, Zhi-Zhong; Essam, J W; Wu, F Y
2014-07-01
We consider the problem of two-point resistance in an (m-1) × n resistor network embedded on a globe, a geometry topologically equivalent to an m × n cobweb with its boundary collapsed into one single point. We deduce a concise formula for the resistance between any two nodes on the globe using a method of direct summation pioneered by one of us [Z.-Z. Tan, L. Zhou, and J. H. Yang, J. Phys. A: Math. Theor. 46, 195202 (2013)]. This method is contrasted with the Laplacian matrix approach formulated also by one of us [F. Y. Wu, J. Phys. A: Math. Gen. 37, 6653 (2004)], which is difficult to apply to the geometry of a globe. Our analysis gives the result in the form of a single summation.
Measurement and correlates of internalized homophobia: a factor analytic study.
Ross, M W; Rosser, B R
1996-01-01
We developed a scale to measure internalized homophobia in men who have sex with men, which is comprised of items derived from theoretical and clinical reports of internalized homophobia. Two hundred two men who have sex with men and who attend "Man to Man" sexual health seminars in a midwestern U.S. city completed the scale at baseline. Orthogonal factor analysis revealed four dimensions of internalized homophobia: public identification as gay, perception of stigma associated with being homosexual, social comfort with gay men, and the moral and religious acceptability of being gay. Factor scoring of these dimensions indicated that they were associated significantly with relationship satisfaction, duration of longest relationship, extent of attraction to men and women, proportion of social time with gay people, membership of gay/bisexual groups, HIV serostatus, and disclosure of sexual orientation. Internalized homophobia is measurable and consists of four dimensions that are associated significantly with low disclosure, shorter length of and satisfaction with relationships, lower degree of sexual attraction to men and higher degree of attraction to women, and lower social time with gay people.
Correlation between precision gravity and subsidence measurements at Cerro Prieto
Zelwer, R.; Grannell, R. B.
1982-10-01
Precision gravity measurements were made in the region of the Cerro Prieto geothermal field at yearly intervals from 1977 to 1981 to assess the feasibility of using gravity to determine subsurface reservoir changes with time. The extent of mass recharge in response to the continued production of fluids from this field was studied. Changes in gravity and ground elevation were observed throughout the region for the period of observation. Results indicate that the largest changes observed were the result of the Magnitude 6.1 (Caltech) Victoria earthquake of 8 June 1980. The epicenter of this earthquake was located 25 km southeast of the field on the Cerro Prieto Fault, which bounds the field on the southwest. Subsidence of up to 55 cm was measured east of the power plant, in the region between the northern end of the Cerro Prieto Fault and the southern end of the Imperial Fault. This area has been postulated to be the site of an active spreading center or pull-apart basin, and has been characterized by a high level of seismic activity during the last 10 years.
Waheed, Umair bin
2013-09-01
On several simple models of isotropic and anisotropic media, we have studied the accuracy of the two-point paraxial traveltime formula designed for the approximate calculation of the traveltime between points S\\' and R\\' located in the vicinity of points S and R on a reference ray. The reference ray may be situated in a 3D inhomogeneous isotropic or anisotropic medium with or without smooth curved interfaces. The twopoint paraxial traveltime formula has the form of the Taylor expansion of the two-point traveltime with respect to spatial Cartesian coordinates up to quadratic terms at points S and R on the reference ray. The constant term and the coefficients of the linear and quadratic terms are determined from quantities obtained from ray tracing and linear dynamic ray tracing along the reference ray. The use of linear dynamic ray tracing allows the evaluation of the quadratic terms in arbitrarily inhomogeneous media and, as shown by examples, it extends the region of accurate results around the reference ray between S and R (and even outside this interval) obtained with the linear terms only. Although the formula may be used for very general 3D models, we concentrated on simple 2D models of smoothly inhomogeneous isotropic and anisotropic (~8% and ~20% anisotropy) media only. On tests, in which we estimated twopoint traveltimes between a shifted source and a system of shifted receivers, we found that the formula may yield more accurate results than the numerical solution of an eikonal-based differential equation. The tests also indicated that the accuracy of the formula depends primarily on the length and the curvature of the reference ray and only weakly depends on anisotropy. The greater is the curvature of the reference ray, the narrower its vicinity, in which the formula yields accurate results.
GONOME: measuring correlations between GO terms and genomic positions
Directory of Open Access Journals (Sweden)
Bailey Timothy L
2006-02-01
Full Text Available Abstract Background: Current methods to find significantly under- and over-represented gene ontology (GO terms in a set of genes consider the genes as equally probable "balls in a bag", as may be appropriate for transcripts in micro-array data. However, due to the varying length of genes and intergenic regions, that approach is inappropriate for deciding if any GO terms are correlated with a set of genomic positions. Results: We present an algorithm – GONOME – that can determine which GO terms are significantly associated with a set of genomic positions given a genome annotated with (at least the starts and ends of genes. We show that certain GO terms may appear to be significantly associated with a set of randomly chosen positions in the human genome if gene lengths are not considered, and that these same terms have been reported as significantly over-represented in a number of recent papers. This apparent over-representation disappears when gene lengths are considered, as GONOME does. For example, we show that, when gene length is taken into account, the term "development" is not significantly enriched in genes associated with human CpG islands, in contradiction to a previous report. We further demonstrate the efficacy of GONOME by showing that occurrences of the proteosome-associated control element (PACE upstream activating sequence in the S. cerevisiae genome associate significantly to appropriate GO terms. An extension of this approach yields a whole-genome motif discovery algorithm that allows identification of many other promoter sequences linked to different types of genes, including a large group of previously unknown motifs significantly associated with the terms 'translation' and 'translational elongation'. Conclusion: GONOME is an algorithm that correctly extracts over-represented GO terms from a set of genomic positions. By explicitly considering gene size, GONOME avoids a systematic bias toward GO terms linked to large genes
Correlates of subjectively and objectively measured physical activity in young adolescents
Directory of Open Access Journals (Sweden)
Kelly Kavanaugh
2015-09-01
Conclusion: Measuring MVPA via self-report versus accelerometry produces considerably different results in a sample of young adolescents. Future studies should use caution when selecting outcome measures if the intent is to identify modifiable correlates of MVPA in youth.
Measurement of Grit and Correlation to Student Pharmacist Academic Performance.
Pate, Adam N; Payakachat, Nalin; Harrell, T Kristopher; Pate, Kristen A; Caldwell, David J; Franks, Amy M
2017-08-01
Objective. To describe grittiness of students from three pharmacy schools and determine if grit is associated with academic performance measures. Methods. Pharmacy students completed an electronic questionnaire that included the Short Grit Scale (Grit-S). Associations were determined using logistic regression. Results. Grit-S total score was a significant and independent predictor for participants who reported a GPA ≥3.5, and Consistency of Interest (COI) and Perseverance of Effort (POE) domain scores were significantly higher compared to participants with a GPA of 3.0-3.49. Participants reporting a D or F had slightly lower average total Grit-S scores and COI domain scores compared to participants who did not. In addition, the group who reported a GPA GPA of 3.0-3.4. Conclusion. Grittiness may be associated with student pharmacist academic performance and the Grit-S Scale may have substantive implications for use in pharmacy programs.
Surface roughness measurement on a wing aircraft by speckle correlation.
Salazar, Félix; Barrientos, Alberto
2013-09-05
The study of the damage of aeronautical materials is important because it may change the microscopic surface structure profiles. The modification of geometrical surface properties can cause small instabilities and then a displacement of the boundary layer. One of the irregularities we can often find is surface roughness. Due to an increase of roughness and other effects, there may be extra momentum losses in the boundary layer and a modification in the parasite drag. In this paper we present a speckle method for measuring the surface roughness on an actual unmanned aircraft wing. The results show an inhomogeneous roughness distribution on the wing, as expected according to the anisotropic influence of the winds over the entire wing geometry. A calculation of the uncertainty of the technique is given.
Correlation coefficient measurement of the mode-locked laser tones using four-wave mixing.
Anthur, Aravind P; Panapakkam, Vivek; Vujicic, Vidak; Merghem, Kamel; Lelarge, Francois; Ramdane, Abderrahim; Barry, Liam P
2016-06-01
We use four-wave mixing to measure the correlation coefficient of comb tones in a quantum-dash mode-locked laser under passive and active locked regimes. We study the uncertainty in the measurement of the correlation coefficient of the proposed method.
The concordance correlation coefficient for repeated measures estimated by variance components.
Carrasco, Josep L; King, Tonya S; Chinchilli, Vernon M
2009-01-01
The concordance correlation coefficient (CCC) is an index that is commonly used to assess the degree of agreement between observers on measuring a continuous characteristic. Here, a CCC for longitudinal repeated measurements is developed through the appropriate specification of the intraclass correlation coefficient from a variance components linear mixed model. A case example and the results of a simulation study are provided.
Two-point L1 shortest path queries in the plane
Directory of Open Access Journals (Sweden)
Danny Z. Chen
2016-12-01
Full Text Available Let $P$ be a set of $h$ pairwise-disjoint polygonal obstacles with a total of $n$ vertices in the plane. We consider the problem of building a data structure that can quickly compute an $L_1$ shortest obstacle-avoiding path between any two query points $s$ and $t$. Previously, a data structure of size $O(n^2\\log n$ was constructed in $O(n^2\\log^2 n$ time that answers each two-point query in $O(\\log^2 n+k$ time, i.e., the shortest path length is reported in $O(\\log^2 n$ time and an actual path is reported in additional $O(k$ time, where $k$ is the number of edges of the output path. In this paper, we build a new data structure of size $O(n+h^2 \\log h 4^{\\sqrt{\\log h}}$ in $O(n+h^2 \\log^{2}h 4^{\\sqrt{\\log h}}$ time that answers each query in $O(\\log n+k$ time. (In contrast, for the Euclidean version of this two-point query problem, the best known algorithm uses $O(n^{11}$ space to achieve an $O(\\log n+k$ query time. Further, we extend our techniques to the weighted rectilinear version in which the ``obstacles" of $P$ are rectilinear regions with ``weights" and allow $L_1$ paths to travel through them with weighted costs. Previously, a data structure of size $O(n^2\\log^2 n$ was built in $O(n^2\\log^2 n$ time that answers each query in $O(\\log^2 n+k$ time. Our new algorithm answers each query in $O(\\log n+k$ time with a data structure of size $O(n^2 \\log n 4^{\\sqrt{\\log n}}$ that is built in $O(n^2 \\log^2 n 4^{\\sqrt{\\log n}}$ time.
An Attempt to Derive the epsilon Equation from a Two-Point Closure
Canuto, V. M.; Cheng, Y.; Howard, A. M.
2010-01-01
The goal of this paper is to derive the equation for the turbulence dissipation rate epsilon for a shear-driven flow. In 1961, Davydov used a one-point closure model to derive the epsilon equation from first principles but the final result contained undetermined terms and thus lacked predictive power. Both in 1987 and in 2001, attempts were made to derive the epsilon equation from first principles using a two-point closure, but their methods relied on a phenomenological assumption. The standard practice has thus been to employ a heuristic form of the equation that contains three empirical ingredients: two constants, c(sub 1 epsilon), and c(sub 2 epsilon), and a diffusion term D(sub epsilon) In this work, a two-point closure is employed, yielding the following results: 1) the empirical constants get replaced by c(sub 1), c(sub 2), which are now functions of Kappa and epsilon; 2) c(sub 1) and c(sub 2) are not independent because a general relation between the two that are valid for any Kappa and epsilon are derived; 3) c(sub 1), c(sub 2) become constant with values close to the empirical values c(sub 1 epsilon), c(sub epsilon 2), (i.e., homogenous flows); and 4) the empirical form of the diffusion term D(sub epsilon) is no longer needed because it gets substituted by the Kappa-epsilon dependence of c(sub 1), c(sub 2), which plays the role of the diffusion, together with the diffusion of the turbulent kinetic energy D(sub Kappa), which now enters the new equation (i.e., inhomogeneous flows). Thus, the three empirical ingredients c(sub 1 epsilon), c(sub epsilon 2), D (sub epsilon)are replaced by a single function c(sub 1)(Kappa, epsilon ) or c(sub 2)(Kappa, epsilon ), plus a D(sub Kappa)term. Three tests of the new equation for epsilon are presented: one concerning channel flow and two concerning the shear-driven planetary boundary layer (PBL).
Energy Technology Data Exchange (ETDEWEB)
Artu, X. [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire; Collins, J. [Pennsylvania State Univ., University Park, PA (United States). Davey Lab.
1996-01-01
The azimuthal distribution of pairs of particles in a jet is sensitive to the transverse polarization of the quark initiating the jet, but with a sensitivity that involves a nonperturbative analyzing power. We show in detail how to measure the analyzing power from 4-hadron correlations in e{sup +}e{sup -} {yields} 2 jets. We explain the combinations of particle flavor that are likely to give the biggest effect. (orig.)
Valassi, A
2014-01-01
We discuss the effect of large positive correlations in the combinations of several measurements of a single physical quantity using the Best Linear Unbiased Estimate (BLUE) method. We suggest a new approach for comparing the relative weights of the different measurements in their contributions to the combined knowledge about the unknown parameter, using the well-established concept of Fisher information. We argue, in particular, that one contribution to information comes from the collective interplay of the measurements through their correlations and that this contribution cannot be attributed to any of the individual measurements alone. We show that negative coefficients in the BLUE weighted average invariably indicate the presence of a regime of high correlations, where the effect of further increasing some of these correlations is that of reducing the error on the combined estimate. In these regimes, we stress that the correlations provided as input to BLUE combinations need to be assessed with extreme ca...
Photon-correlation measurements of atomic-cloud temperature using an optical nanofiber
Grover, J A; Orozco, L A; Rolston, S L
2015-01-01
We develop a temperature measurement of an atomic cloud based on the temporal correlations of fluorescence photons evanescently coupled into an optical nanofiber. We measure the temporal width of the intensity-intensity correlation function due to atomic transit time and use it to determine the most probable atomic velocity, hence the temperature. This technique agrees well with standard time-of-flight temperature measurements. We confirm our results with trajectory simulations.
High dynamic range multi-channel cross-correlator for single-shot temporal contrast measurement
Kon, A.; Nishiuchi, M.; Kiriyama, H.; Ogura, K.; Mori, M.; Sakaki, H.; Kando, M.; Kondo, K.
2016-05-01
We have developed a multi-channel cross-correlator for high dynamic range (>1010), single-shot temporal contrast measurements. The correlator utilizes a third-order crosscorrelation technique and has a reference channel, to be normalized by the measured peak intensity, and four independent optical delay lines. The measurement results of the shot-to-shot temporal contrast clearly show the intensity fluctuations of short pre-pulses at -4.5 ps and -26 ps before main pulse.
Covariant and infrared-free graviton two-point function in de Sitter spacetime II
Pejhan, Hamed
2016-01-01
The solution to the linearized Einstein equation in de Sitter (dS) spacetime and the corresponding two-point function are explicitly written down in a gauge with two parameters `$a$' and `$b$'. The quantization procedure, independent of the choice of the coordinate system, is based on a rigorous group theoretical approach. Our result takes the form of a universal spin-two (transverse-traceless) sector and a gauge-dependent spin-zero (pure-trace) sector. Scalar equations are derived for the structure functions of each part. We show that the spin-two sector can be written as the resulting action of a second-order differential operator (the spin-two projector) on a massless minimally coupled scalar field (the spin-two structure function). The operator plays the role of a symmetric rank-$2$ polarization tensor and has a spacetime dependence. The calculated spin-two projector grows logarithmically with distance and also no dS-invariant solution for either structure functions exist. We show that the logarithmically...
Directory of Open Access Journals (Sweden)
Andrius Gaizauskas
2014-01-01
Full Text Available Indication has led ureteroscopy to be a worldwide technique, with the expected appearance of multiple types of complications. Severe complications are possible including ureteral perforation or avulsion. Ureteral avulsion has been described as an upper urinary tract injury related to the action of blunt trauma, especially from traffic accidents, being the mechanism of injury, the result of an acute deceleration/acceleration movement. With the advent of endourology, that term is also applied to the extensive degloving injury resulting from a mechanism of stretching of the ureter that eventually breaks at the most weakened site, or ureteral avulsion is referred to as a discontinuation of the full thickness of the ureter. The paper presents a case report and literature review of the two-point or “scabbard” avulsion. The loss of long segment of the upper ureter, when end-to-end anastomosis is not technically feasible, presents a challenge to the urological surgeon. In the era of small calibre ureteroscopes these complications, due to growing incidence of renal stones will become more and more actual. Our message to other urologists is to know such a complication, to know the ways of treatment, and to analyse ureteroscopic signs, when to stop or pay attention.
Exteroceptive aspects of nociception: insights from graphesthesia and two-point discrimination.
Mørch, Carsten Dahl; Andersen, Ole K; Quevedo, Alexandre S; Arendt-Nielsen, Lars; Coghill, Robert C
2010-10-01
The exteroceptive capabilities of the nociceptive system have long been thought to be considerably more limited than those of the tactile system. However, most investigations of spatio-temporal aspects of the nociceptive system have largely focused on intensity coding as consequence of spatial or temporal summation. Graphesthesia, the identification of numbers "written" on the skin, and assessment of the two-point discrimination thresholds were used to compare the exteroceptive capabilities of the tactile and nociceptive systems. Numbers were "written" on the forearm and the abdomen by tactile stimulation and by painful non-contact infrared laser heat stimulation. Subjects performed both graphesthesia tasks better than chance. The tactile graphesthesia tasks were performed with 89% (82-97%) correct responses on the forearm and 86% (79-94%) correct responses on the abdomen. Tactile graphesthesia tasks were significantly better than painful heat graphesthesia tasks that were performed with 31% (23-40%) and 44% (37-51%) correct responses on the forearm and abdomen, respectively. These findings demonstrate that the central nervous system is capable of assembling complex spatio-temporal patterns of nociceptive information from the body surface into unified mental objects with sufficient accuracy to enable behavioral discrimination.
Assessing Performance of Multipurpose Reservoir System Using Two-Point Linear Hedging Rule
Sasireka, K.; Neelakantan, T. R.
2017-07-01
Reservoir operation is the one of the important filed of water resource management. Innovative techniques in water resource management are focussed at optimizing the available water and in decreasing the environmental impact of water utilization on the natural environment. In the operation of multi reservoir system, efficient regulation of the release to satisfy the demand for various purpose like domestic, irrigation and hydropower can lead to increase the benefit from the reservoir as well as significantly reduces the damage due to floods. Hedging rule is one of the emerging techniques in reservoir operation, which reduce the severity of drought by accepting number of smaller shortages. The key objective of this paper is to maximize the minimum power production and improve the reliability of water supply for municipal and irrigation purpose by using hedging rule. In this paper, Type II two-point linear hedging rule is attempted to improve the operation of Bargi reservoir in the Narmada basin in India. The results obtained from simulation of hedging rule is compared with results from Standard Operating Policy, the result shows that the application of hedging rule significantly improved the reliability of water supply and reliability of irrigation release and firm power production.
Angular correlations of identified charged particles measured in pp collisions by ALICE at the LHC
Energy Technology Data Exchange (ETDEWEB)
Graczykowski, Łukasz Kamil, E-mail: lgraczyk@if.pw.edu.pl; Janik, Małgorzata Anna, E-mail: majanik@if.pw.edu.pl
2014-06-15
We report on studies of untriggered two-particle angular correlations of identified particles (pions, kaons and protons) measured in proton–proton collisions at center-of-mass energy √(s)=7 TeV recorded by ALICE at the LHC. These type of studies are sensitive to a wide range of correlations which arise from different physics mechanisms, each of them having a unique structure in ΔηΔφ space. The correlations of particles with different quark content and flavor are sensitive to various conservation laws. The study of these correlations is the main goal of this analysis. The results confirm that these laws strongly influence the shape of the correlation functions for different particle types and must be taken into account while analyzing the data. Moreover, we verify their implementation using two Monte Carlo event generators and we found that the analyzed models do not reproduce the measured correlations for protons.
Variance in population firing rate as a measure of slow time-scale correlation
Directory of Open Access Journals (Sweden)
Adam C. Snyder
2013-12-01
Full Text Available Correlated variability in the spiking responses of pairs of neurons, also known as spike count correlation, is a key indicator of functional connectivity and a critical factor in population coding. Underscoring the importance of correlation as a measure for cognitive neuroscience research is the observation that spike count correlations are not fixed, but are rather modulated by perceptual and cognitive context. Yet while this context fluctuates from moment to moment, correlation must be calculated over multiple trials. This property undermines its utility as a dependent measure for investigations of cognitive processes which fluctuate on a trial-to-trial basis, such as selective attention. A measure of functional connectivity that can be assayed on a moment-to-moment basis is needed to investigate the single-trial dynamics of populations of spiking neurons. Here, we introduce the measure of population variance in normalized firing rate for this goal. We show using mathematical analysis, computer simulations and in vivo data how population variance in normalized firing rate is inversely related to the latent correlation in the population, and how this measure can be used to reliably classify trials from different typical correlation conditions, even when firing rate is held constant. We discuss the potential advantages for using population variance in normalized firing rate as a dependent measure for both basic and applied neuroscience research.
DEFF Research Database (Denmark)
Jacobsen, R. H.; Birkelund, Karen; Holst, T.;
1996-01-01
Photocurrent correlation measurements used for the characterization of ultrafast photoconductive switches based on GaAs and silicon-on-sapphire are demonstrated. The correlation signal arises from the interplay of the photoexcited carriers, the dynamics of the bias field and a subsequent rechargi...
Correlation Attenuation Due to Measurement Error: A New Approach Using the Bootstrap Procedure
Padilla, Miguel A.; Veprinsky, Anna
2012-01-01
Issues with correlation attenuation due to measurement error are well documented. More than a century ago, Spearman proposed a correction for attenuation. However, this correction has seen very little use since it can potentially inflate the true correlation beyond one. In addition, very little confidence interval (CI) research has been done for…
Gordon, David M; Ash, Stephen R
2009-01-01
The purpose of this research project was to determine whether the glucose level of a blood plasma sample from a diabetic patient could be predicted by measuring the density and conductivity of ultrafiltrate of plasma created by a 30,000 m.w. cutoff membrane. Conductivity of the plasma filtrate measures electrolyte concentration and should correct density measurements for changes in electrolytes and water concentration. In vitro studies were performed measuring conductivity and density of solutions of varying glucose and sodium chloride concentrations. Plasma from seven hospitalized patients with diabetes was filtered across a 30,000 m.w. cutoff membrane. The filtrate density and conductivity were measured and correlated to glucose levels. In vitro studies confirmed the ability to predict glucose from density and conductivity measurements, in varying concentrations of glucose and saline. In plasma filtrate, the conductivity and density measurements of ultrafiltrate allowed estimation of glucose in some patients with diabetes but not others. The correlation coefficient for the combined patient data was 0.45 which was significant but only explained 20% of the variability in the glucose levels. Individually, the correlation was significant in only two of the seven patients with correlation coefficients of 0.79 and 0.88. The reasons for lack of correlation are not clear, and cannot be explained by generation of idiogenic osmoles, effects of alcohol dehydrogenase, water intake, etc. This combination of physical methods for glucose measurement is not a feasible approach to measuring glucose in plasma filtrate.
Expected properties of the Two-Point Autocorrelation Function of the IGM
Ursino, Eugenio; Galeazzi, Massimiliano; Marulli, Federico; Moscardini, Lauro; Piro, Luigi; Roncarelli, Mauro; Takei, Yoh
2010-01-01
Recent analyses of the fluctuations of the soft Diffuse X-ray Background (DXB) have provided indirect detection of a component consistent with the elusive Warm Hot Intergalactic Medium (WHIM). In this work we use theoretical predictions obtained from hydrodynamical simulations to investigate the angular correlation properties of the WHIM in emission and assess the possibility of indirect detection with next-generation X-ray missions. Our results indicate that the angular correlation signal of the WHIM is generally weak but dominates the angular correlation function of the DXB outside virialized regions. Its indirect detection is possible but requires rather long exposure times [0.1-1] Ms, large (~1{\\deg} x1{\\deg}) fields of view and accurate subtraction of isotropic fore/background contributions, mostly contributed by Galactic emission. The angular correlation function of the WHIM is positive for {\\theta} < 5' and provides limited information on its spatial distribution. A satisfactory characterization of ...
Measurements of texture properties related to tenderness at different locations within deboned broiler breast fillets have been used to validate techniques for texture analysis and establish correlations between different texture evaluation methods. However, it has been demonstrated that meat text...
Field methods to measure surface displacement and strain with the Video Image Correlation method
Maddux, Gary A.; Horton, Charles M.; Mcneill, Stephen R.; Lansing, Matthew D.
1994-01-01
The objective of this project was to develop methods and application procedures to measure displacement and strain fields during the structural testing of aerospace components using paint speckle in conjunction with the Video Image Correlation (VIC) system.
Correlation and agreement: overview and clarification of competing concepts and measures.
Liu, Jinyuan; Tang, Wan; Chen, Guanqin; Lu, Yin; Feng, Changyong; Tu, Xin M
2016-04-25
Agreement and correlation are widely-used concepts that assess the association between variables. Although similar and related, they represent completely different notions of association. Assessing agreement between variables assumes that the variables measure the same construct, while correlation of variables can be assessed for variables that measure completely different constructs. This conceptual difference requires the use of different statistical methods, and when assessing agreement or correlation, the statistical method may vary depending on the distribution of the data and the interest of the investigator. For example, the Pearson correlation, a popular measure of correlation between continuous variables, is only informative when applied to variables that have linear relationships; it may be non-informative or even misleading when applied to variables that are not linearly related. Likewise, the intraclass correlation, a popular measure of agreement between continuous variables, may not provide sufficient information for investigators if the nature of poor agreement is of interest. This report reviews the concepts of agreement and correlation and discusses differences in the application of several commonly used measures.
One and two dimensional analysis of 3$\\pi$ correlations measured in Pb+Pb interactions
Bearden, I G; Boissevain, J G; Christiansen, P; Conin, L; Dodd, J; Erazmus, B; Esumi, S C; Fabjan, Christian Wolfgang; Ferenc, D; Fields, D E; Franz, A; Gaardhøje, J J; Hansen, A G; Hansen, O; Hardtke, D; van Hecke, H; Holzer, E B; Humanic, T J; Hummel, P; Jacak, B V; Jayanti, R; Kaimi, K; Kaneta, M; Kohama, T; Kopytine, M L; Leltchouk, M; Ljubicic, A; Lörstad, B; Maeda, N; Martin, L; Medvedev, A; Murray, M; Ohnishi, H; Paic, G; Pandey, S U; Piuz, François; Pluta, J; Polychronakos, V; Potekhin, M V; Poulard, G; Reichhold, D M; Sakaguchi, A; Schmidt-Sørensen, J; Simon-Gillo, J; Sondheim, W E; Sugitate, T; Sullivan, J P; Sumi, Y; Willis, W J; Wolf, K L; Xu, N; Zachary, D S
2001-01-01
$\\pi^{-}\\pi^{-}\\pi^{-}$ correlations from Pb+Pb collisions at 158 GeV/c per nucleon are presented as measured by the focusing spectrometer of the NA44 experiment at CERN. The three-body effect is found to be stronger for PbPb than for SPb. The two-dimensional three-particle correlation function is also measured and the longitudinal extension of the source is larger than the transverse extension.
2012-02-01
AFRL-RZ-WP-TP-2012-0100 CORRELATION OF AC LOSS DATA FROM MAGNETIC SUSCEPTIBILITY MEASUREMENTS WITH YBCO FILM QUALITY (POSTPRINT) Paul N...CORRELATION OF AC LOSS DATA FROM MAGNETIC SUSCEPTIBILITY MEASUREMENTS WITH YBCO FILM QUALITY (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT...spreading of the temperature-dependent ac susceptibility curves with increasing applied magnetic field, the quality of the YBCO film generally
Correlates of subjectively and objectively measured physical activity in young adolescents
Institute of Scientific and Technical Information of China (English)
Kelly Kavanaugh; Justin B. Moore; Leisha Johnson Hibbett; Andrew T. Kaczynski
2015-01-01
Background:Many studies examining individual-level correlates in youth utilize self-report rather than objective measures of physical activity (PA). This utilization of self-report may result in associations that are not present when examining objectively measured PA. The present study investigates the relationship between hypothesized correlates of PA with objectively and subjectively measured PA. Methods: Participating children (n = 232, 101 males, mean age = 12.3 years) provided a minimum of four monitored days of PA (via accelerometer) and completed a survey assessing moderate-to-vigorous physical activity (MVPA), sport competence, appearance, enjoyment, and self-efficacy. Height and weight were measured and body mass index (BMI) was calculated. Results: Hierarchical regression models controlling for sex, race, and BMI Z-score showed that only sex and BMI Z-score were significant correlates of objective MVPA while only sex was a significant correlate of objective total PA. However, in a separate model examining the relationship with subjective MVPA, enjoyment of PA and self-efficacy for PA were the only significant correlates of self-reported PA. Conclusion:Measuring MVPA via self-report versus accelerometry produces considerably different results in a sample of young adolescents. Future studies should use caution when selecting outcome measures if the intent is to identify modifiable correlates of MVPA in youth.
Devillard, P.; Chevallier, D.; Albert, M.
2017-09-01
We compute various current-correlation functions of electrons flowing from a topological nanowire to the tip of a superconducting scanning tunnel microscope and identify fingerprints of a Majorana bound state. In particular, the spin resolved cross correlations are shown to display a clear distinction between the presence of a such an exotic state (negative correlations) and an Andreev bound state (positive correlations). Similarity and differences with measurements with a normal tunnel microscope are also discussed, like the robustness to finite temperature, for instance.
Noh, Ji-Woong; Park, Byoung-Sun; Kim, Mee-Young; Lee, Lim-Kyu; Yang, Seung-Min; Lee, Won-Deok; Shin, Yong-Sub; Kang, Ji-Hye; Kim, Ju-Hyun; Lee, Jeong-Uk; Kwak, Taek-Yong; Lee, Tae-Hyun; Kim, Ju-Young; Kim, Junghwan
2015-06-01
[Purpose] This study investigated two-point discrimination (TPD) and the electrical sensory threshold of the blind to define the effect of using Braille on the tactile and electrical senses. [Subjects and Methods] Twenty-eight blind participants were divided equally into a text-reading and a Braille-reading group. We measured tactile sensory and electrical thresholds using the TPD method and a transcutaneous electrical nerve stimulator. [Results] The left palm TPD values were significantly different between the groups. The values of the electrical sensory threshold in the left hand, the electrical pain threshold in the left hand, and the electrical pain threshold in the right hand were significantly lower in the Braille group than in the text group. [Conclusion] These findings make it difficult to explain the difference in tactility between groups, excluding both palms. However, our data show that using Braille can enhance development of the sensory median nerve in the blind, particularly in terms of the electrical sensory and pain thresholds.
A robust measure of correlation between two genes on a microarray
Directory of Open Access Journals (Sweden)
Hicks Leanne
2007-06-01
Full Text Available Abstract Background The underlying goal of microarray experiments is to identify gene expression patterns across different experimental conditions. Genes that are contained in a particular pathway or that respond similarly to experimental conditions could be co-expressed and show similar patterns of expression on a microarray. Using any of a variety of clustering methods or gene network analyses we can partition genes of interest into groups, clusters, or modules based on measures of similarity. Typically, Pearson correlation is used to measure distance (or similarity before implementing a clustering algorithm. Pearson correlation is quite susceptible to outliers, however, an unfortunate characteristic when dealing with microarray data (well known to be typically quite noisy. Results We propose a resistant similarity metric based on Tukey's biweight estimate of multivariate scale and location. The resistant metric is simply the correlation obtained from a resistant covariance matrix of scale. We give results which demonstrate that our correlation metric is much more resistant than the Pearson correlation while being more efficient than other nonparametric measures of correlation (e.g., Spearman correlation. Additionally, our method gives a systematic gene flagging procedure which is useful when dealing with large amounts of noisy data. Conclusion When dealing with microarray data, which are known to be quite noisy, robust methods should be used. Specifically, robust distances, including the biweight correlation, should be used in clustering and gene network analysis.
Melconian, D; Fenker, B; Mehlman, M; Shidling, P D; Anholm, M; Ashery, D; Behr, J A; Gorelov, A; Gwinner, G; Olchankski, K; Smale, S
2014-01-01
The correlations of the decay products following the beta decay of nuclei have a long history of providing a low-energy probe of the fundamental symmetries of our universe. Over half a century ago, the correlation of the electrons following the decay of polarized 60Co demonstrated that parity is not conserved in weak interactions. Today, the same basic idea continues to be applied to search for physics beyond the standard model: make precision measurements of correlation parameters and look for deviations compared to their standard model predictions. Efforts to measure these parameters to the 0.1% level utilizing atom and ion trapping techniques are described.
Measurement of Spin Correlation in Top Quark Pair Production in Semi-Leptonic Final State
Baarmand, Marc M; Vodopiyanov, Igor
2006-01-01
The measurement of correlation between spins of top and anti-top quarks, produced in proton-proton collisions at LHC, is described for the semi-leptonic decay of the top quark pair (one top quark decaying leptonically and the other hadronically). The simulated events are reconstructed after full simulation of the CMS detector. The spin correlation coefficient is estimated based on a total integrated luminosity of ten inverse femtobarns. Including systematic uncertainties, the correlation coefficient can be measured with a total relative uncertainty of 17% or 27% depending on the choice of the deay angles used.
Energy Technology Data Exchange (ETDEWEB)
Henninger, B.; Rauch, S.; Schocke, M.; Jaschke, W.; Kremser, C. [Medical University of Innsbruck, Department of Radiology, Innsbruck (Austria); Zoller, H. [Medical University of Innsbruck, Department of Internal Medicine, Innsbruck (Austria); Kannengiesser, S. [Siemens AG, Healthcare Sector, MR Applications Development, Erlangen (Germany); Zhong, X. [Siemens Healthcare, MR R and D Collaborations, Atlanta, GA (United States); Reiter, G. [Siemens AG, Healthcare Sector, MR R and D Collaborations, Graz (Austria)
2015-05-01
To evaluate the automated two-point Dixon screening sequence for the detection and estimated quantification of hepatic iron and fat compared with standard sequences as a reference. One hundred and two patients with suspected diffuse liver disease were included in this prospective study. The following MRI protocol was used: 3D-T1-weighted opposed- and in-phase gradient echo with two-point Dixon reconstruction and dual-ratio signal discrimination algorithm (''screening'' sequence); fat-saturated, multi-gradient-echo sequence with 12 echoes; gradient-echo T1 FLASH opposed- and in-phase. Bland-Altman plots were generated and correlation coefficients were calculated to compare the sequences. The screening sequence diagnosed fat in 33, iron in 35 and a combination of both in 4 patients. Correlation between R2* values of the screening sequence and the standard relaxometry was excellent (r = 0.988). A slightly lower correlation (r = 0.978) was found between the fat fraction of the screening sequence and the standard sequence. Bland-Altman revealed systematically lower R2* values obtained from the screening sequence and higher fat fraction values obtained with the standard sequence with a rather high variability in agreement. The screening sequence is a promising method with fast diagnosis of the predominant liver disease. It is capable of estimating the amount of hepatic fat and iron comparable to standard methods. (orig.)
Evaluation of cross correlation technique to measure flow in pipes of the oil industry
Energy Technology Data Exchange (ETDEWEB)
Avilan, Eddie J., E-mail: eddieavilan@gmail.com [Universidad Central de Venezuela (UCV), Facultad de Ingenieria, Departamento de Fisica Aplicada, Caracas (Venezuela, Bolivarian Republic of); Reis, Verginia, E-mail: verginia@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Barreira, Luis E.; Salgado, Cesar Marques, E-mail: brandao@ien.gov.br, E-mail: otero@ien.gov.br [Instituto de Engenharia Nuclear (DIRA/IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Divisao de Radiofarmacos
2013-07-01
The present work is concerned with the use of the cross correlation technique to measure delay time between two simulated signals displaced with respect to time, in order to develop a cross correlator system that will be used to measure the water and oil pipes flowrate in which the detection system is composed by two external low intensity radiation sources located along the tube and two NaI(Tl) gamma-ray detectors. The final purpose of the correlator system is to use the natural disturbances, as the turbulence in the own flow rather than to inject radioactive tracers to the fluid flow as usually is carried out. In the design of this correlator is evaluated the point-by-point calculation method for the cross correlation function in order to produce a system accurate and fast. This method is divided at the same time in three modes of operation: direct, relay and polarity. (author)
Field-measured drag area is a key correlate of level cycling time trial performance
Directory of Open Access Journals (Sweden)
James E. Peterman
2015-08-01
Full Text Available Drag area (Ad is a primary factor determining aerodynamic resistance during level cycling and is therefore a key determinant of level time trial performance. However, Ad has traditionally been difficult to measure. Our purpose was to determine the value of adding field-measured Ad as a correlate of level cycling time trial performance. In the field, 19 male cyclists performed a level (22.1 km time trial. Separately, field-determined Ad and rolling resistance were calculated for subjects along with projected frontal area assessed directly (AP and indirectly (Est AP. Also, a graded exercise test was performed to determine $\\dot {V}{O}_{2}$V̇O2 peak, lactate threshold (LT, and economy. $\\dot {V}{O}_{2}$V̇O2 peak ($\\mathrm{l}~\\min ^{-1}$lmin−1 and power at LT were significantly correlated to power measured during the time trial (r = 0.83 and 0.69, respectively but were not significantly correlated to performance time (r = − 0.42 and −0.45. The correlation with performance time improved significantly (p < 0.05 when these variables were normalized to Ad. Of note, Ad alone was better correlated to performance time (r = 0.85, p < 0.001 than any combination of non-normalized physiological measure. The best correlate with performance time was field-measured power output during the time trial normalized to Ad (r = − 0.92. AP only accounted for 54% of the variability in Ad. Accordingly, the correlation to performance time was significantly lower using power normalized to AP (r = − 0.75 or Est AP (r = − 0.71. In conclusion, unless normalized to Ad, level time trial performance in the field was not highly correlated to common laboratory measures. Furthermore, our field-measured Ad is easy to determine and was the single best predictor of level time trial performance.
Theory and signal processing of acoustic correlation techniques for current velocity measurement
Institute of Scientific and Technical Information of China (English)
ZHU Weiqing; FENG Lei; WANG Changhong; WANG Yuling; QIU Wei
2008-01-01
A theoretical model and signal processing of acoustic correlation measurements to estimate current velocity are discussed. The sonar space-time correlation function of vol-ume reverberations within Fraunhofer zone is derived. The function, which is in exponential forms, is the theoretical model of acoustic correlation measurements. The characteristics of the correlation values around the maximum of the amplitude of the correlation function, where most information about current velocity is contained, are primarily analyzed. Localized Least Mean Squares (LLMS) criterion is put forward for velocity estimation. Sequential Quadratic Programming (SQP) method is adopted as the optimization method. So the systematic sig-nal processing method of acoustic correlation techniques for current velocity measurement is established. A prototype acoustic correlation current profiler (ACCP) underwent several sea trials, the results show that theoretical model approximately coincides with experimental re-sults. Current profiles including the speed and direction from ACCP are compared with those from acoustic Doppler current profiler (ADCP). The current profiles by both instruments agree reasonably well. Also, the standard deviation of velocity measurement by ACCP is statistically calculated and it is a little larger than predicted value.
Joint Measurement of Lensing-Galaxy Correlations Using SPT and DES SV Data
Baxter, E J; Giannantonio, T; Dodelson, S; Jain, B; Huterer, D; Bleem, L E; Crawford, T M; Efstathiou, G; Fosalba, P; Kirk, D; Kwan, J; Sánchez, C; Story, K T; Troxel, M A; Abbott, T M C; Abdalla, F B; Armstrong, R; Benoit-Lévy, A; Benson, B A; Bernstein, G M; Bernstein, R A; Bertin, E; Brooks, D; Carlstrom, J E; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Chown, R; Crocce, M; Cunha, C E; D'Andrea, C B; da Costa, L N; Desai, S; Diehl, H T; Dietrich, J P; Doel, P; Evrard, A E; Neto, A Fausti; Flaugher, B; Frieman, J; Gruen, D; Gruendl, R A; Gutierrez, G; de Haan, T; Holder, G P; Honscheid, K; Hou, Z; James, D J; Kuehn, K; Kuropatkin, N; Lima, M; March, M; Marshall, J L; Martini, P; Melchior, P; Miller, C J; Miquel, R; Mohr, J J; Nord, B; Omori, Y; Plazas, A A; Reichardt, C L; Romer, A K; Rykoff, E S; Sanchez, E; Sevilla-Noarbe, I; Sheldon, E; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Stark, A A; Swanson, M E C; Tarle, G; Thomas, D; Walker, A R; Wechsler, R H
2016-01-01
We measure the correlation of galaxy lensing and cosmic microwave background lensing with a set of galaxies expected to trace the matter density field. The measurements are performed using pre-survey Dark Energy Survey (DES) Science Verification optical imaging data and millimeter-wave data from the 2500 square degree South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey. The two lensing-galaxy correlations are jointly fit to extract constraints on cosmological parameters, constraints on the redshift distribution of the lens galaxies, and constraints on the absolute shear calibration of DES galaxy lensing measurements. We show that an attractive feature of these fits is that they are fairly insensitive to the clustering bias of the galaxies used as matter tracers. The measurement presented in this work confirms that DES and SPT data are consistent with each other and with the currently favored $\\Lambda$CDM cosmological model. It also demonstrates that joint lensing-galaxy correlation measurement considered ...
Maximum key-profile correlation (MKC) as a measure of tonal structure in music.
Takeuchi, A H
1994-09-01
Tonal structure is musical organization on the basis of pitch, in which pitches vary in importance and rate of occurrence according to their relationship to a tonal center. Experiment 1 evaluated the maximum key-profile correlation (MKC), a product of Krumhansl and Schmuckler's key-finding algorithm (Krumhansl, 1990), as a measure of tonal structure. The MKC is the maximum correlation coefficient between the pitch class distribution in a musical sample and key profiles, which indicate the stability of pitches with respect to particular tonal centers. The MKC values of melodies correlated strongly with listeners' ratings of tonal structure. To measure the influence of the temporal order of pitches on perceived tonal structure, three measures (fifth span, semitone span, and pitch contour) taken from previous studies of melody perception were also correlated with tonal structure ratings. None of the temporal measures correlated as strongly or as consistently with tonal structure ratings as did the MKC, and nor did combining them with the MKC improve prediction of tonal structure ratings. In Experiment 2, the MKC did not correlate with recognition memory of melodies. However, melodies with very low MKC values were recognized less accurately than melodies with very high MKC values. Although it does not incorporate temporal, rhythmic, or harmonic factors that may influence perceived tonal structure, the MKC can be interpreted as a measure of tonal structure, at least for brief melodies.
Vibration measurement based on the optical cross-correlation technique with femtosecond pulsed laser
Han, Jibo; Wu, Tengfei; Zhao, Chunbo; Li, Shuyi
2016-10-01
Two vibration measurement methods with femtosecond pulsed laser based on the optical cross-correlation technique are presented independently in this paper. The balanced optical cross-correlation technique can reflect the time jitter between the reference pluses and measurement pluses by detecting second harmonic signals using type II phase-matched nonlinear crystal and balanced amplified photo-detectors. In the first method, with the purpose of attaining the vibration displacement, the time difference of the reference pulses relative to the measurement pluses can be measured using single femtosecond pulsed laser. In the second method, there are a couple of femtosecond pulsed lasers with high pulse repetition frequency. Vibration displacement associated with cavity length can be calculated by means of precisely measuring the pulse repetition frequency. The results show that the range of measurement attains ±150μm for a 500fs pulse. These methods will be suited for vibration displacement measurement, including laboratory use, field testing and industrial application.
Azimuthal correlations in Pb--Pb and pp collisions measured with the ALICE detector
DEFF Research Database (Denmark)
Zhou, You; Collaboration, for the ALICE
2012-01-01
We present results from the measurements of azimuthal correlations of charged particles in $\\sqrt{s_{_{NN}}}$ = 2.76 TeV Pb--Pb collisions and $\\sqrt{s_{_{NN}}}$ = 7 TeV pp collisions. In addition, the comparison of the experimental measurements in pp collisions with those from Pythia and Phojet...
Principles of azimuthal correlation measurement of J/psi with charged hadrons
Maire, Antonin
2012-01-01
Schematic illustration of measurement variables in the azimuthal J/psi-hadron correlation measurement. The z-axis perpendicular to the x-y-plane corresponds to the beam axis in the experiment. The reconstructed e+e- pairs are only identifiable as J/psi mesons on a statistical basis.
DEFF Research Database (Denmark)
Eldrup, Morten Mostgaard; Lund-Thomsen, E.; Mogensen, O. E.
1972-01-01
The dose dependence of the relative EPR signal intensity and positron lifetime spectrum was measured for γ‐irradiated acetyl methionine in the dose range from 0 to 30 Mrad. Angular correlation measurements were performed for the doses 0 and 30 Mrad. The result of the irradiation was the creation...
A Simple Superresolution Approach of Multipath Delay Profiles Measured by PN Correlation Method
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Time resolution of multipath delay profiles measured by using autocorrelation of pseudonoise (PN) code sequence is generally limitec by the chip rate of the PN code sequence. In this paper, we propose a simple method to improve the time resolution of delay profiles measured by the PN correlation method. Effectiveness of this method is demonstrated by indoor wireless propagation experiments.
Simulating network throughput by correlating perfSONAR measurements with link utilisation
Babik, Marian; CERN. Geneva. IT Department
2017-01-01
In this report the modeling of the network performance through delay and packet loss measurements is explored. It is shown that correlations exists and different models are proposed to exploit them. In addition, the developed models are then implemented into the existing network measurement platform and made available to general use.
Conditional purity and quantum correlation measures in two qubit mixed states
Rebón, L.; Rossignoli, R.; Varga, J. J. M.; Gigena, N.; Canosa, N.; Iemmi, C.; Ledesma, S.
2016-11-01
We analyze and show experimental results of the conditional purity, the quantum discord and other related measures of quantum correlation in mixed two-qubit states constructed from a pair of photons in identical polarization states. The considered states are relevant for the description of spin pair states in interacting spin chains in a transverse magnetic field. We derive clean analytical expressions for the conditional local purity and other correlation measures obtained as a result of a remote local projective measurement, which are fully verified by the experimental results. A simple exact expression for the quantum discord of these states in terms of the maximum conditional purity is also derived.
Validation of SAGE II aerosol measurements by comparison with correlative sensors
Swissler, T. J.
1986-01-01
The SAGE II limb-scanning radiometer carried on the Earth Radiation Budget Satellite functions at wavelengths of 0.385, 0.45, 0.525, and 1.02 microns to identify vertical profiles of aerosol density by atmospheric extinction measurements from cloud tops upward. The data are being validated by correlating the satellite data with data gathered with, e.g., lidar, sunphotometer, and dustsonde instruments. Work thus far has shown that the 1 micron measurements from the ground and satellite are highly correlated and are therefore accurate to within measurement uncertainty.
Gradl, Paul
2016-01-01
NASA Marshall Space Flight Center (MSFC) has been advancing dynamic optical measurement systems, primarily Digital Image Correlation, for extreme environment rocket engine test applications. The Digital Image Correlation (DIC) technology is used to track local and full field deformations, displacement vectors and local and global strain measurements. This technology has been evaluated at MSFC through lab testing to full scale hotfire engine testing of the J-2X Upper Stage engine at Stennis Space Center. It has been shown to provide reliable measurement data and has replaced many traditional measurement techniques for NASA applications. NASA and AMRDEC have recently signed agreements for NASA to train and transition the technology to applications for missile and helicopter testing. This presentation will provide an overview and progression of the technology, various testing applications at NASA MSFC, overview of Army-NASA test collaborations and application lessons learned about Digital Image Correlation.
Zhuang, H; Savage, E M
2009-01-01
Measurements of texture properties related to tenderness at different locations within deboned broiler breast fillets have been used to validate techniques for texture analysis and establish correlations between different texture evaluation methods. However, it has been demonstrated that meat texture can vary from location to location within individual muscles. The objective of our study was to investigate the intramuscular variation and Pearson correlation coefficients of Warner-Bratzler (WB) shear force measurements within early deboned broiler breast fillets and the effect of deboning time and cold storage on the variation and correlation coefficients. Broiler breast fillets were removed from carcasses early postmortem (2 h) and later postmortem (24 h). Storage treatments of the 2 h samples included 0 d, 7 d at 3 degrees C, 7 d at -20 degrees C, and 6 d at -20 degrees C plus 1 d at 3 degrees C. The WB shears of cooked fillets were measured using a TA-XTPlus Texture Analyzer and a TA-7 WB shear type blade. Our results showed that although the average WB shear force values differed within the 0-d, 2-h fillets, compared with the variation among the fillets within the treatment, the difference within a fillet is still evidently small. The Pearson correlation coefficients were significant between the locations; however, values of the correlation coefficients depended on the paired locations. Location differences in the WB shear values and the correlation coefficient values between them changed with deboning time and cold storage. These results demonstrate that the variation of WB shear force measurements is substantial within early deboned broiler breast fillets and the Pearson correlation coefficient values of the measurements vary among the locations. Both the variation and the Pearson correlation coefficients can be affected by postmortem aging time and storage. The differences in the means between the locations in early deboned breasts are much smaller than the
CORRELATION BETWEEN SOME BODY MEASURES OF LIPPIZANER STALLION PER LINES AT ĐAKOVO STUD
Directory of Open Access Journals (Sweden)
T. Rastija
2002-06-01
Full Text Available Body measures of Lippizaner line stallions and their correlation were processed in Đakovo stud. The measures performed by Lydtin rod and stock band included withers height, chest girth and cannon bone circumference on the total of 75 heads. Neapolitano line was characterized by the fewest number of stallions (4 whereas Tulip by the largest one (20. Data attained by the measuring were processed by the statistical program SPSS/PC (Nie et. al. 1975. Neapolitano line stallions had the lowest withers height (164.00 cm measured by the band whereas Conversano line stallions had the highest one (166.33 cm. Withers height measured by the rod was the lowest in the Maestoso line stallion (156.50 cm and the highest one in the Favory line (159.20 cm. Chest girth ranged between 183.82 cm (Pluto line and 186.89 cm (Conversano line. Cannon bone circumference was uniform with all lines ranged from 20.05 cm (Tulipan line and 20.65 cm (Maestoso lines. Correlation between withers height measured by the band and rod and that one measured by the rod and chest girth was positive and highly significant. However, correlation between others ranged from slight positive to slight negative. Neapolitano line was known for the most pronounced correlation per lines whereas Tulip line for the weakest one. Correlation between withers height measured by the band and rod was in all lines highly significant (except Tulip line whereas other correlation varied from positive to negative.
Simultaneous Differential Polarimetric Measurements and Co-Polar Correlation Coefficient Measurement
National Oceanic and Atmospheric Administration, Department of Commerce — A polarimetric Doppler weather radar system which allows measurement of linear orthogonal polarimetric variables without a switch by using simultaneous transmission...
Reddy, V R; Reddy, T G; Reddy, P Y; Reddy, K R
2003-01-01
An AC modulation technique is described to convert stochastic signal variations into an amplitude variation and its retrieval through Fourier analysis. It is shown that this AC detection of signals of stochastic processes when processed through auto- and cross-correlation techniques improve the signal-to-noise ratio; the correlation techniques serve a similar purpose of frequency and phase filtering as that of phase-sensitive detection. A few model calculations applied to nuclear spectroscopy measurements such as Angular Correlations, Mossbauer spectroscopy and Pulse Height Analysis reveal considerable improvement in the sensitivity of signal detection. Experimental implementation of the technique is presented in terms of amplitude variations of harmonics representing the derivatives of normal spectra. Improved detection sensitivity to spectral variations is shown to be significant. These correlation techniques are general and can be made applicable to all the fields of particle counting where measurements ar...
Evans, G. F.; Haller, R. G.; Wyrick, P. S.; Parkey, R. W.; Fleckenstein, J. L.; Blomqvist, C. G. (Principal Investigator)
1998-01-01
PURPOSE: To assess correlations between muscle edema on magnetic resonance (MR) images and clinical indexes of muscle injury in delayed-onset muscle soreness (DOMS) produced by submaximal exercise protocols. MATERIALS AND METHODS: Sixteen subjects performed 36 elbow flexions ("biceps curls") at one of two submaximal workloads that emphasized eccentric contractions. Changes in MR imaging findings, plasma levels of creatine kinase, and pain scores were correlated. RESULTS: Both exercise protocols produced DOMS in all subjects. The best correlation was between change in creatine kinase level and volume of muscle edema on MR images, regardless of the workload. Correlations tended to be better with the easier exercise protocol. CONCLUSION: Whereas many previous studies of DOMS focused on intense exercise protocols to ensure positive results, the present investigation showed that submaximal workloads are adequate to produce DOMS and that correlations between conventionally measured indexes of injury may be enhanced at lighter exercise intensities.
Correlates of objectively measured sedentary time and self-reported screen time in Canadian children
LeBlanc, Allana G; Stephanie T Broyles; Chaput, Jean-Philippe; Leduc, Geneviève; Boyer, Charles; Borghese, Michael M.; Tremblay, Mark S
2015-01-01
Background Demographic, family, and home characteristics play an important role in determining childhood sedentary behaviour. The objective of this paper was to identify correlates of total sedentary time (SED) and correlates of self-reported screen time (ST) in Canadian children. Methods Child- and parent-reported household, socio-demographic, behavioural, and diet related data were collected; directly measured anthropometric and accelerometer data were also collected for each child. Partici...
Measuring the correlation of two optical frequencies using four-wave mixing.
Anthur, Aravind P; Watts, Regan T; Huynh, Tam N; Venkitesh, Deepa; Barry, Liam P
2014-11-10
We use the physics of four-wave mixing to study the decorrelation of two optical frequencies as they propagate through different fiber delays. The phase noise relationship between the four-wave mixing components is used to quantify and measure the correlation between the two optical frequencies using the correlation coefficient. We show the difference in the evolution of decorrelation between frequency-dependent and frequency-independent components of phase noise.
Walczak, Zbigniew; Wintrowicz, Iwona
2017-03-01
Recently, Brodutch and Modi proposed a general method of constructing meaningful measures of classical and quantum correlations. We systematically apply this method to obtain geometric classical and quantum correlations based on the Bures and the trace distances for two-qubit Bell diagonal states. Moreover, we argue that in general the Brodutch and Modi method may provide non-unique results, and we show how to modify this method to avoid this issue.
Measurement of the Correlation and Coherence Lengths in Boundary Layer Flight Data
Palumbo, Daniel L.
2011-01-01
Wall pressure data acquired during flight tests at several flight conditions are analyzed and the correlation and coherence lengths of the data reported. It is shown how the frequency bandwidth of the analysis biases the correlation length and how the convection of the flow acts to reduce the coherence length. Coherence lengths measured in the streamwise direction appear much longer than would be expected based on classical results for flow over a flat plat.
The negativity of Wigner function as a measure of quantum correlations
Siyouri, F.; El Baz, M.; Hassouni, Y.
2016-10-01
In this paper, we study comparatively the behaviors of Wigner function and quantum correlations for two quasi-Werner states formed with two general bipartite superposed coherent states. We show that the Wigner function can be used to detect and quantify the quantum correlations. However, we show that it is in fact not sensitive to all kinds of quantum correlations but only to entanglement. Then, we analyze the measure of non-classicality of quantum states based on the volume occupied by the negative part of the Wigner function.
Energy Technology Data Exchange (ETDEWEB)
Bulzacchelli, John F [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Lee, Hae-Seung [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Hong, Merit Y [Motorola, Inc., Semiconductor Products Sector, Tempe, AZ 85284 (United States); Misewich, James A [IBM Research Division, T J Watson Research Center, Yorktown Heights, NY 10598 (United States); Ketchen, Mark B [IBM Research Division, T J Watson Research Center, Yorktown Heights, NY 10598 (United States)
2003-12-01
Segmented correlation is a useful technique for testing a superconducting analogue-to-digital converter, as it allows the output spectrum to be estimated with fine frequency resolution even when data record lengths are limited by small on-chip acquisition memories. Previously, we presented segmented correlation measurements on a superconducting bandpass delta-sigma modulator sampling at 40.2 GHz under idle channel (no input) conditions. This paper compares the modulator output spectra measured by segmented correlation with and without an input tone. Important practical considerations of calculating segmented correlations are discussed in detail. Resolution enhancement by segmented correlation does reduce the spectral width of the input tone in the desired manner, but the signal power due to the input increases the variance of the spectral estimate near the input frequency, hindering accurate calculation of the in-band noise. This increased variance, which is predicted by theory, must be considered carefully in the application of segmented correlation. Methods for obtaining more accurate estimates of the quantization noise spectrum which are closer to those measured with no input are described.
Bulzacchelli, John F.; Lee, Hae-Seung; Hong, Merit Y.; Misewich, James A.; Ketchen, Mark B.
2003-12-01
Segmented correlation is a useful technique for testing a superconducting analogue-to-digital converter, as it allows the output spectrum to be estimated with fine frequency resolution even when data record lengths are limited by small on-chip acquisition memories. Previously, we presented segmented correlation measurements on a superconducting bandpass delta-sigma modulator sampling at 40.2 GHz under idle channel (no input) conditions. This paper compares the modulator output spectra measured by segmented correlation with and without an input tone. Important practical considerations of calculating segmented correlations are discussed in detail. Resolution enhancement by segmented correlation does reduce the spectral width of the input tone in the desired manner, but the signal power due to the input increases the variance of the spectral estimate near the input frequency, hindering accurate calculation of the in-band noise. This increased variance, which is predicted by theory, must be considered carefully in the application of segmented correlation. Methods for obtaining more accurate estimates of the quantization noise spectrum which are closer to those measured with no input are described.
Shi, Lizheng; Liu, Jinan; Fonseca, Vivian; Walker, Philip; Kalsekar, Anupama; Pawaskar, Manjiri
2010-09-13
It is vital to understand the associations between the medication event monitoring systems (MEMS) and self-reported questionnaires (SRQs) because both are often used to measure medication adherence and can produce different results. In addition, the economic implication of using alternative measures is important as the cost of electronic monitoring devices is not covered by insurance, while self-reports are the most practical and cost-effective method in the clinical settings. This meta-analysis examined the correlations of two measurements of medication adherence: MEMS and SRQs. The literature search (1980-2009) used PubMed, OVID MEDLINE, PsycINFO (EBSCO), CINAHL (EBSCO), OVID HealthStar, EMBASE (Elsevier), and Cochrane Databases. Studies were included if the correlation coefficients [Pearson (rp) or Spearman (rs)] between adherences measured by both MEMS and SRQs were available or could be calculated from other statistics in the articles. Data were independently abstracted in duplicate with standardized protocol and abstraction form including 1) first author's name; 2) year of publication; 3) disease status of participants; 4) sample size; 5) mean age (year); 6) duration of trials (month); 7) SRQ names if available; 8) adherence (%) measured by MEMS; 9) adherence (%) measured by SRQ; 10) correlation coefficient and relative information, including p-value, 95% confidence interval (CI). A meta-analysis was conducted to pool the correlation coefficients using random-effect model. Eleven studies (N = 1,684 patients) met the inclusion criteria. The mean of adherence measured by MEMS was 74.9% (range 53.4%-92.9%), versus 84.0% by SRQ (range 68.35%-95%). The correlation between adherence measured by MEMS and SRQs ranged from 0.24 to 0.87. The pooled correlation coefficient for 11 studies was 0.45 (p = 0.001, 95% confidence interval [95% CI]: 0.34-0.56). The subgroup meta-analysis on the seven studies reporting rp and four studies reporting rs reported the pooled
MEASURING SEA ICE DRIFT VIA CROSS-CORRELATION OF RADAR ICE IMAGES
Institute of Scientific and Technical Information of China (English)
SUN He-quan; SHEN Yong-ming; Qiu Da-hong
2004-01-01
The motion of sea ice has a great effect on winter navigation, and oil field exploration in the Bohai Sea. It is very important to measure the ice drift accurately and efficiently. As a practical technique, radar imagery has been used for sea ice monitoring and forecasting for a long time. Combining with the radar imagery and cross-correlation technique, a new measurement method based on the cross-correlation of radar ice images is specified in this paper to obtain full field measurement of sea ice drift. The theory and fast implementation of cross-correlation are presented briefly in the paper, including the filtering method to modify the invalid vectors. To show deeply the validity of the present method, the velocity maps of sea ice drift are provided in the paper, which are calculated from the radar images grabbed in the Liaodong Gulf. The comparison with the traditional tracing method is also conducted.
DEFF Research Database (Denmark)
Holstein, P; Lassen, N A
1980-01-01
The frequency of healing in subchronic ulcers in 66 feet in 62 patients with arterial occlusive disease was correlated with the systolic digital blood pressure (SDBP) and the systolic ankle blood pressure (SABP), both measured with a strain gauge, and with the skin perfusion pressure on the heel...... of healing correlated significantly with the three distal blood pressure parameters investigated, the closest correlation being with the SDBP measured at the final examination, i.e. just after healing of the ulcer or just before an inevitable major amputation. Of the 22 cases with SDBP below 20 mmHg only two...... (SPPH) as measured with a photocell. Thirty-two patients (35 feet with ulcerations) had diabetes mellitus. The treatment was conservative. In 42 feet the ulcers healed after an average period of 5.8 months; in 24 feet major amputation became necessary after an average of 4.3 months. The frequency...
A problem with the correlation coefficient as a measure of gene expression divergence.
Pereira, Vini; Waxman, David; Eyre-Walker, Adam
2009-12-01
The correlation coefficient is commonly used as a measure of the divergence of gene expression profiles between different species. Here we point out a potential problem with this statistic: if measurement error is large relative to the differences in expression, the correlation coefficient will tend to show high divergence for genes that have relatively uniform levels of expression across tissues or time points. We show that genes with a conserved uniform pattern of expression have significantly higher levels of expression divergence, when measured using the correlation coefficient, than other genes, in a data set from mouse, rat, and human. We also show that the Euclidean distance yields low estimates of expression divergence for genes with a conserved uniform pattern of expression.
Measuring a hidden coordinate: Rate-exchange kinetics from 3D correlation functions
Berg, Mark A.; Darvin, Jason R.
2016-08-01
Nonexponential kinetics imply the existence of at least one slow variable other than the observable, that is, the system has a "hidden" coordinate. We develop a simple, but general, model that allows multidimensional correlation functions to be calculated for these systems. Homogeneous and heterogeneous mechanisms are both included, and slow exchange of the rates is allowed. This model shows that 2D and 3D correlation functions of the observable measure the distribution and kinetics of the hidden coordinate controlling the rate exchange. Both the mean exchange time and the shape of the exchange relaxation are measurable. However, complications arise because higher correlation functions are sums of multiple "pathways," each of which measures different dynamics. Only one 3D pathway involves exchange dynamics. Care must be used to extract exchange dynamics without contamination from other processes.
Measurement of the $t\\bar{t}$ spin correlations and top quark polarization in dileptonic channel
Khatiwada, Ajeeta
2017-01-01
The degree of top polarization and strength of $t\\bar{t}$ correlation are dependent on production dynamics, decay mechanism, and choice of the observables. At the LHC, measurement of the top polarization and spin correlations in $t\\bar{t}$ production is possible through various observables related to the angular distribution of decay leptons. A measurement of differential distribution provides a precision test of the standard model of particle physics and probes for deviations, which could be a sign of new physics. In particular, the phase space for the super-symmetric partner of the top quark can be constrained. Results from the Compact Muon Solenoid (CMS) collaboration for top quark polarization and spin correlation in the dileptonic channel are reviewed briefly in this proceeding. The measurements are obtained using 19.5 fb$^{-1}$ of data collected in pp collisions at the center-of-mass energy of 8 TeV.
Measuring a hidden coordinate: Rate-exchange kinetics from 3D correlation functions.
Berg, Mark A; Darvin, Jason R
2016-08-07
Nonexponential kinetics imply the existence of at least one slow variable other than the observable, that is, the system has a "hidden" coordinate. We develop a simple, but general, model that allows multidimensional correlation functions to be calculated for these systems. Homogeneous and heterogeneous mechanisms are both included, and slow exchange of the rates is allowed. This model shows that 2D and 3D correlation functions of the observable measure the distribution and kinetics of the hidden coordinate controlling the rate exchange. Both the mean exchange time and the shape of the exchange relaxation are measurable. However, complications arise because higher correlation functions are sums of multiple "pathways," each of which measures different dynamics. Only one 3D pathway involves exchange dynamics. Care must be used to extract exchange dynamics without contamination from other processes.
Measurement of b anti b correlations at the CERN p anti p collider
Energy Technology Data Exchange (ETDEWEB)
Albajar, C.; Ankoviak, K.; Bartha, S.; Bezaguet, A.; Boehrer, A.; Bos, K.; Buchanan, C.; Buschbeck, B.; Castilla-Valdez, H.; Cennini, P.; Cittolin, S.; Clayton, E.; Cline, D.; Caughlan, J.A.; Dau, D.; Daum, C.; Della Negra, M.; Demoulin, M.; Denegri, D.; Dibon, H.; Dorenbosch, J.; Dowell, J.D.; Eggert, K.; Eisenhandler, E.; Ellis, N.; Evans, H.; Faissner, H.; Fensome, I.F.; Fortson, L.; Garvey, J.; Geiser, A. Givernaud, A.; Gonidec, A.; Gonzalez, B.; Gronberg, J.; Holthuizen, D.J.; Jank, W.; Jorat, G.; Kalmus, P.I.P.; Karimaeki, V.; Kenyon, I.; Kinnunen, R.; Krammer, M.; Lammel, S.; Landon, M.P.J.; Lemoigne, Y.; Levegruen, S.; Lipa, P.; Markou, C.; Markytan, M.; Maurin, G.; McMahon, S.; Merlo, J.P.; Meyer, T.; Moers, T.; Mohammadi, M.; Morsch, A.; Moulin, A.; Norton, A.; Otwinowski, S.; Pancheri, G.; Pietarinen, E.; Pimiae, M.; Placci, A.; Porte, J.P.; Priem, R.; Prosi, R.; Radermacher, E.; Rauschkolb, M.; Reithler, H.; Revol, J.P.; Robinson, D.; Rubbia, C.; Samyn, D.; Schinzel, D.; Sc; UA1 Collaboration
1994-01-01
We report on measurements of correlated b anti b production in p anti p at [radical]s=630 GeV, using dimuon data to tag both the b and anti b quarks. Starting from an inclusive dimuon sample we obtain improved cross-sections for single inclusive beauty production and confirm our earlier results on B[sup 0]- anti B[sup 0] mixing. From a study of b anti b correlations we derive explicit cross-sections for semi-differential b anti b production. We compare the measured cross-sections and correlations to OMIKRON ([alpha][sub s][sup 3]) QCD predictions and find good quantitative agreement. From the measured angular distributions we establish a sizeable contribution from higher order QCD processes with a significance of about seven standard deviations. A large nonperturbative contribution to these higher order corrections is excluded. (orig.)
Song, John; Chu, Wei; Tong, Mingsi; Soons, Johannes
2014-06-01
Based on three-dimensional (3D) topography measurements on correlation cells, the National Institute of Standards and Technology (NIST) has developed the ‘NIST Ballistics Identification System (NBIS)’ aimed at accurate ballistics identifications and fast ballistics evidence searches. The 3D topographies are divided into arrays of correlation cells to identify ‘valid correlation areas’ and eliminate ‘invalid correlation areas’ from the matching and identification procedure. A ‘congruent matching cells’ (CMC)’ method using three types of identification parameters of the paired correlation cells (cross correlation function maximum CCFmax, spatial registration position in x-y and registration angle θ) is used for high accuracy ballistics identifications. ‘Synchronous processing’ is proposed for correlating multiple cell pairs at the same time to increase the correlation speed. The proposed NBIS can be used for correlations of both geometrical topographies and optical intensity images. All the correlation parameters and algorithms are in the public domain and subject to open tests. An error rate reporting procedure has been developed that can greatly add to the scientific support for the firearm and toolmark identification specialty, and give confidence to the trier of fact in court proceedings. The NBIS is engineered to employ transparent identification parameters and criteria, statistical models and correlation algorithms. In this way, interoperability between different ballistics identification systems can be more easily achieved. This interoperability will make the NBIS suitable for ballistics identifications and evidence searches with large national databases, such as the National Integrated Ballistic Information Network in the United States.
Energy Technology Data Exchange (ETDEWEB)
Yoon, Jung Hyun, E-mail: lvjenny0417@gmail.com [Department of Radiology, CHA Bundang Medical Center, CHA University, School of Medicine (Korea, Republic of); Department of Radiology, Research Institute of Radiological Science, Yonsei University, College of Medicine (Korea, Republic of); Ko, Kyung Hee, E-mail: yourheeya@cha.ac.kr [Department of Radiology, CHA Bundang Medical Center, CHA University, School of Medicine (Korea, Republic of); Jung, Hae Kyoung, E-mail: AA40501@cha.ac.kr [Department of Radiology, CHA Bundang Medical Center, CHA University, School of Medicine (Korea, Republic of); Lee, Jong Tae, E-mail: jtlee@cha.ac.kr [Department of Radiology, CHA Bundang Medical Center, CHA University, School of Medicine (Korea, Republic of)
2013-12-01
Objective: To determine the correlation of qualitative shear wave elastography (SWE) pattern classification to quantitative SWE measurements and whether it is representative of quantitative SWE values with similar performances. Methods: From October 2012 to January 2013, 267 breast masses of 236 women (mean age: 45.12 ± 10.54 years, range: 21–88 years) who had undergone ultrasonography (US), SWE, and subsequent biopsy were included. US BI-RADS final assessment and qualitative and quantitative SWE measurements were recorded. Correlation between pattern classification and mean elasticity, maximum elasticity, elasticity ratio and standard deviation were evaluated. Diagnostic performances of grayscale US, SWE parameters, and US combined to SWE values were calculated and compared. Results: Of the 267 breast masses, 208 (77.9%) were benign and 59 (22.1%) were malignant. Pattern classifications significantly correlated with all quantitative SWE measurements, showing highest correlation with maximum elasticity, r = 0.721 (P < 0.001). Sensitivity was significantly decreased in US combined to SWE measurements to grayscale US: 69.5–89.8% to 100.0%, while specificity was significantly improved: 62.5–81.7% to 13.9% (P < 0.001). Area under the ROC curve (A{sub z}) did not show significant differences between grayscale US to US combined to SWE (P > 0.05). Conclusion: Pattern classification shows high correlation to maximum stiffness and may be representative of quantitative SWE values. When combined to grayscale US, SWE improves specificity of US.
A New Approach to Measuring the Neutron Decay Correlations with Cold Neutrons at LANSCE
Energy Technology Data Exchange (ETDEWEB)
Wilburn, W.S.; Bowman, J.D.; Greene, G.L.; Jones, G.L.; Kapustinsky, J.S.; Penttila, S.I.
1999-06-08
Precision measurements of the neutron beta-decay correlations A, B, a, and b provide important tests of the standard model of electroweak interactions: a test of the unitarity of the first row of the CKM matrix, a search for new weak interactions, a test of the theory of nuclear beta decays, and a test of the conserved-vector-current hypothesis. The authors are designing an experiment at the LANSCE short-pulse spallation source to measure all four correlations to an order of magnitude better accuracy than the existing measurements. The accuracy of the previous measurements was limited by systematics. The design of the proposed experiment makes use of the pulsed nature of the LANSCE source to reduce systematic errors associated with the measurement of the neutron polarization as well as other systematic errors. In addition, the authors are developing silicon strip detectors for detecting both the proton and electron from the neutron decay.
Directory of Open Access Journals (Sweden)
S.M. Badwai
2013-01-01
Full Text Available the key point of super resolution process is the accurate measuring of sub-pixel shift. Any tiny error in measuring such shift leads to an incorrect image focusing. In this paper, methodology of measuring sub-pixel shift using Phase correlation (PC are evaluated using different window functions, then modified version of (PC method using high pass filter (HPF is introduced . Comprehensive analysis and assessment of (PC methods shows that different natural features yield different shift measurements. It is concluded that there is no universal window function for measuring shift; it mainly depends on the features in the satellite images. Even the question of which window is optimal of particular feature is generally remains open. This paper presents the design of a method for obtaining high accuracy sub pixel shift phase correlation using (HPF.The proposed method makes the change in the different locations that lack of edges easy.
Sub-cycle measurement of intensity correlations in the Terahertz range
Benea-Chelmus, Ileana-Cristina; Beck, Mattias; Faist, Jerome
2015-01-01
The Terahertz frequency range bears intriguing opportunities, beyond very advanced applications in spectroscopy and matter control. Peculiar quantum phenomena are predicted to lead to light emission by non-trivial mechanisms. Typically, such emission mechanisms are unraveled by temporal correlation measurements of photon arrival times, as demonstrated in their pioneering work by Hanbury Brown and Twiss. So far, the Terahertz range misses an experimental implementation of such technique with very good temporal properties and high sensitivity. In this paper, we propose a room-temperature scheme to measure photon correlations at THz frequencies based on electro-optic sampling. The temporal resolution of 146 fs is faster than one cycle of oscillation and the sensitivity is so far limited to ~1500 photons. With this technique, we measure the photon statistics of a THz quantum cascade laser. The proposed measurement scheme allows, in principle, the measurement of ultrahigh bandwidth photons and paves the way toward...
Lebreton, A; Braive, R; Sagnes, I; Robert-Philip, I; Beveratos, A
2013-01-01
Interferometric photon-correlation measurements, which correspond to the second-order intensity cross-correlations between the two output ports of an unbalanced Michelson interferometer, are sensitive to both amplitude and phase fluctuations of an incoming beam of light. Here, we present the theoretical framework behind these measurements and show that they can be used to unambiguously differentiate a coherent wave undergoing dynamical amplitude and phase fluctuations from a chaotic state of light. This technique may thus be used to characterize the output of nanolasers and monitor the onset of coherent emission.
Nieminen, Teemu; Lähteenmäki, Pasi; Tan, Zhenbing; Cox, Daniel; Hakonen, Pertti J.
2016-11-01
We present a microwave correlation measurement system based on two low-cost USB-connected software defined radio dongles modified to operate as coherent receivers by using a common local oscillator. Existing software is used to obtain I/Q samples from both dongles simultaneously at a software tunable frequency. To achieve low noise, we introduce an easy low-noise solution for cryogenic amplification at 600-900 MHz based on single discrete HEMT with 21 dB gain and 7 K noise temperature. In addition, we discuss the quantization effects in a digital correlation measurement and determination of optimal integration time by applying Allan deviation analysis.
Volatility and correlation-based systemic risk measures in the US market
Civitarese, Jamil
2016-10-01
This paper deals with the problem of how to use simple systemic risk measures to assess portfolio risk characteristics. Using three simple examples taken from previous literature, one based on raw and partial correlations, another based on the eigenvalue decomposition of the covariance matrix and the last one based on an eigenvalue entropy, a Granger-causation analysis revealed some of them are not always a good measure of risk in the S&P 500 and in the VIX. The measures selected do not Granger-cause the VIX index in all windows selected; therefore, in the sense of risk as volatility, the indicators are not always suitable. Nevertheless, their results towards returns are similar to previous works that accept them. A deeper analysis has shown that any symmetric measure based on eigenvalue decomposition of correlation matrices, however, is not useful as a measure of "correlation" risk. The empirical counterpart analysis of this proposition stated that negative correlations are usually small and, therefore, do not heavily distort the behavior of the indicator.
Energy Technology Data Exchange (ETDEWEB)
Kong Dexing [Department of Mathematics, Zhejiang University, Hangzhou 310027 (China); Sun Qingyou, E-mail: qysun@cms.zju.edu.cn [Center of Mathematical Sciences, Zhejiang University, Hangzhou 310027 (China)
2011-04-01
All articles must In this paper we introduce some new concepts for second-order hyperbolic equations: two-point boundary value problem, global exact controllability and exact controllability. For several kinds of important linear and nonlinear wave equations arising from physics and geometry, we prove the existence of smooth solutions of the two-point boundary value problems and show the global exact controllability of these wave equations. In particular, we investigate the two-point boundary value problem for one-dimensional wave equation defined on a closed curve and prove the existence of smooth solution which implies the exact controllability of this kind of wave equation. Furthermore, based on this, we study the two-point boundary value problems for the wave equation defined on a strip with Dirichlet or Neumann boundary conditions and show that the equation still possesses the exact controllability in these cases. Finally, as an application, we introduce the hyperbolic curvature flow and obtain a result analogous to the well-known theorem of Gage and Hamilton for the curvature flow of plane curves.
Van der Hofstad, R.; Hara, T.; Slade, G.
2003-01-01
We consider spread-out models of self-avoiding walk, bond percolation, lattice trees and bond lattice animals on ${\\mathbb{Z}^d}$, having long finite-range connections, above their upper critical dimensions $d=4$ (self-avoiding walk), $d=6$ (percolation) and $d=8$ (trees and animals). The two-point
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
In this paper, we consider a two-point boundary value problem for a system of second order ordinary differential equations. Under some conditions, we show the existence of positive solution to the system of second order ordinary differential equa-tions.
Institute of Scientific and Technical Information of China (English)
王同科
2002-01-01
In this paper, a high accuracy finite volume element method is presented for two-point boundary value problem of second order ordinary differential equation, which differs fromthe high order generalized difference methods. It is proved that the method has optimal order er-ror estimate O(h3) in H1 norm. Finally, two examples show that the method is effective.
Lin, Tingting; Zhang, Siyuan; Zhang, Yang; Wan, Ling; Lin, Jun
2017-01-01
Compared with the other geophysical approaches, magnetic resonance sounding (MRS) technique is direct and nondestructive in subsurface water exploration. It provides water content distribution and estimates hydrogeological properties. The biggest challenge is that MRS measurement always suffers bad signal-to-noise ratio, and it can be carried out only far from sources of noise. To solve this problem, a series of de-noising methods are developed. However, most of them are post-processing, leading the data quality uncontrolled for in situ measurements. In the present study, a new approach that removal of correlated noise online is found to overcome the restriction. Based on LabVIEW, a method is provided to enable online data quality control by the way of realizing signal acquisition and noise filtering simultaneously. Using one or more reference coils, adaptive noise cancellation based on LabVIEW to eliminate the correlated noise is available for in situ measurements. The approach was examined through numerical simulation and field measurements. The correlated noise is mitigated effectively and the application of MRS measurements is feasible in high-level noise environment. The method shortens the measurement time and improves the measurement efficiency.
Park, Dae Woo; Kruger, Grant H; Rubin, Jonathan M; Hamilton, James; Gottschalk, Paul; Dodde, Robert E; Shih, Albert J; Weitzel, William F
2013-10-01
This study investigated the use of ultrasound speckle decorrelation- and correlation-based lateral speckle-tracking methods for transverse and longitudinal blood velocity profile measurement, respectively. By studying the blood velocity gradient at the vessel wall, vascular wall shear stress, which is important in vascular physiology as well as the pathophysiologic mechanisms of vascular diseases, can be obtained. Decorrelation-based blood velocity profile measurement transverse to the flow direction is a novel approach, which provides advantages for vascular wall shear stress measurement over longitudinal blood velocity measurement methods. Blood flow velocity profiles are obtained from measurements of frame-to-frame decorrelation. In this research, both decorrelation and lateral speckle-tracking flow estimation methods were compared with Poiseuille theory over physiologic flows ranging from 50 to 1000 mm/s. The decorrelation flow velocity measurement method demonstrated more accurate prediction of the flow velocity gradient at the wall edge than the correlation-based lateral speckle-tracking method. The novelty of this study is that speckle decorrelation-based flow velocity measurements determine the blood velocity across a vessel. In addition, speckle decorrelation-based flow velocity measurements have higher axial spatial resolution than Doppler ultrasound measurements to enable more accurate measurement of blood velocity near a vessel wall and determine the physiologically important wall shear.
McEwen, J D; Hobson, M P; Vandergheynst, P; Lasenby, A N
2007-01-01
Using local morphological measures on the sphere defined through a steerable wavelet analysis, we examine the three-year WMAP and the NVSS data for correlation induced by the integrated Sachs-Wolfe (ISW) effect. The steerable wavelet constructed from the second derivative of a Gaussian allows one to define three local morphological measures, namely the signed-intensity, orientation and elongation of local features. Detections of correlation between the WMAP and NVSS data are made with each of these morphological measures. The most significant detection is obtained in the correlation of the signed-intensity of local features at a significance of 99.9%. By inspecting signed-intensity sky maps, it is possible for the first time to see the correlation between the WMAP and NVSS data by eye. Foreground contamination and instrumental systematics in the WMAP data are ruled out as the source of all significant detections of correlation. Our results provide new insight on the ISW effect by probing the morphological nat...
Correlations between the disintegration of melt and the measured impulses in steam explosions
Energy Technology Data Exchange (ETDEWEB)
Froehlich, G.; Linca, A.; Schindler, M. [Univ. of Stuttgart (Germany)
1995-09-01
To find our correlations in steam explosions (melt water interactions) between the measured impulses and the disintegration of the melt, experiments were performed in three configurations i.e. stratified, entrapment and jet experiments. Linear correlations were detected between the impulse and the total surface of the fragments. Theoretical considerations point out that a linear correlation assumes superheating of a water layer around the fragments of a constant thickness during the fragmentation process to a constant temperature (here the homogeneous nucleation temperature of water was assumed) and a constant expansion velocity of the steam in the main expansion time. The correlation constant does not depend on melt temperature and trigger pressure, but it depends on the configuration of the experiment or of a scenario of an accident. Further research is required concerning the correlation constant. For analysing steam explosion accidents the explosivity is introduced. The explosivity is a mass specific impulse. The explosivity is linear correlated with the degree of fragmentation. Knowing the degree of fragmentation with proper correlation constant the explosivity can be calculated and from the explosivity combined with the total mass of fragments the impulse is obtained which can be used to an estimation of the maximum force.
Zheng, Tianxiang; Cao, Liangcai; Zhao, Tian; He, Qingsheng; Jin, Guofan
2012-10-01
Volume holographic optical correlator can compute the correlation results between images at a super-high speed. In the application of remote imaging processing such as scene matching, 6,000 template images have been angularly multiplexed in the photorefractive crystal and the 6,000 parallel processing channels are achieved. In order to detect the correlation pattern of images precisely and distinguishingly, an on-off pixel inverted technology of images is proposed. It can fully use the CCD's linear range for detection and expand the normalized correlation value differences as the target image rotates. Due to the natural characteristics of the remote sensing images, the statistical formulas between the rotation distortions and the correlation results can be estimated. The rotation distortion components can be estimated by curve fitting method with the data of correlation results. The intensities of the correlation spots are related to the distortion between the two images. The rotation distortion could be derived from the intensities in the post processing procedure. With 18 rotations of the input image and sending them into the volume holographic system, the detection of the rotation variation in the range of 180° can be fulfilled. So the large range rotation distortion detection is firstly realized. It offers a fast, large range rotation measurement method for image distortions.
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The correlation between ground motion intensity measures (IM) and single-degree-of-freedom (SDOF) deformation demands is described in this study. Peak ground acceleration (APG), peak ground velocity (VPG), peak ground displacement (DPG), spectral acceleration at the first-mode period of vibration [As(T1)] and ratio of VPG to APG are used as IM parameters, and the correlation is characterized by correlation coefficients ρ. The numerical results obtained by nonlinear dynamic analyses have shown good correlation between As(T1) or VPG and deformation demands. Furthermore, the effect of As(T1) and VPG as IM on the dispersion of the mean value of deformation demands is also investigated for SDOF systems with three different periods T=0.3 s, 1.0 s, 3.0 s respectively.
Measurement of 21 cm brightness fluctuations at z ~ 0.8 in cross-correlation
Masui, K W; Banavar, N; Bandura, K; Blake, C; Calin, L -M; Chang, T -C; Chen, X; Li, Y -C; Liao, Y -W; Natarajan, A; Pen, U -L; Peterson, J B; Shaw, J R; Voytek, T C
2012-01-01
In this letter, 21 cm intensity maps acquired at the Green Bank Telescope are cross-correlated with large-scale structure traced by galaxies in the WiggleZ Dark Energy Survey. The data span the redshift range 0.6 < z < 1 over two fields totaling ~41 deg. sq. and 190 hours of radio integration time. The cross-correlation constrains Omega_HI b_HI r = [0.43 \\pm 0.07 (stat.) \\pm 0.04(sys.)] x 10^-3, where Omega_HI is the neutral hydrogen HI fraction, r is the galaxy-hydrogen correlation coefficient, and b_HI is the HI bias parameter. This is the most precise constraint on neutral hydrogen density fluctuations in a challenging redshift range. Our measurement improves the previous 21 cm cross-correlation at z ~ 0.8 both in its precision and in the range of scales probed.
Correlation between the Cogstate computerized measure and WAIS-IV among birth cohort mothers.
Kataja, Eeva-Leena; Karlsson, Linnea; Tolvanen, Mimmi; Parsons, Christine; Schembri, Adrian; Kiiski-Mäki, Hanna; Karlsson, Hasse
2017-03-01
Large studies, with limited resources call for cost-effective cognitive assessment methods. Computerized tests offer viable alternatives but more data are needed on their functioning. Our aim was to evaluate the overlap between a computerized neuropsychological test battery and a traditional test of general intelligence (IQ). Cognitive functioning was assessed in birth cohort mothers (n = 80) with two widely used methods: Cogstate, computerized test battery, and WAIS-IV, a traditional IQ test. Correlational analyses were conducted. We found weak-to-moderate correlations between the measures, except for verbal comprehension. The indices of overall performance showed more consistent correlations than Subtests. The overall correlations were in accordance with earlier studies. Cogstate is relatively independent of verbal comprehension abilities. The choice of the cognitive assessment method should be strongly guided by the research question. More studies are needed to evaluate the applicability of the Cogstate Composite Score in cognitive screening.
Institute of Scientific and Technical Information of China (English)
Shuo Zhang,Yan Zhao,Min Li,; Jianhui Zhao
2015-01-01
The global y optimal recursive filtering problem is stu-died for a class of systems with random parameter matrices, stochastic nonlinearities, correlated noises and missing measure-ments. The stochastic nonlinearities are presented in the system model to reflect multiplicative random disturbances, and the addi-tive noises, process noise and measurement noise, are assumed to be one-step autocorrelated as wel as two-step cross-correlated. A series of random variables is introduced as the missing rates governing the intermittent measurement losses caused by un-favorable network conditions. The aim of the addressed filtering problem is to design an optimal recursive filter for the uncertain systems based on an innovation approach such that the filtering error is global y minimized at each sampling time. A numerical simulation example is provided to il ustrate the effectiveness and applicability of the proposed algorithm.
A Novel Three-Head Ultrasonic System for Distance Measurements Based on the Correlation Method
Directory of Open Access Journals (Sweden)
Gądek Krzysztof
2014-12-01
Full Text Available A novel double-emitter ultrasonic system for distance measurements based on the correlation method is presented. The proposed distance measurement method may be particularly useful in difficult conditions, e.g. for media parameters undergoing fast changes or in cases when obstacles and mechanical interference produce false reflections. The system is a development of a previously studied single-head idea. The present article covers a comparison of the two systems in terms of efficiency and precision. Experimental research described in this paper indicated that adding the second head improved the measurement exactness – standard deviation decreased by 40%. The correlation method is also described in detail, also giving the criterion for the quality of the measurement signal.
Correlation of Spherical Thermistor for the Measurement of Low Velocity Air Flow
Institute of Scientific and Technical Information of China (English)
Xin－GangLiang; Ying－PingZhang; 等
1998-01-01
A spherical thermistor,an accurate temperature sensor is employed as an air velocity sensor in this work.The measuring principle is derived and the effects of the insulation layer,air temperature,netural convection and thermal radiation are discussed.Two different correlation relations for velocity measurements are proposed based on theoretical analyses and experimental calibrations,Experiments have shown that spherical thermistor is a good velocity sensor for speed between 0.1-2.5m/s at room temperature and the insulation layer hardly influences the accuracy of the thermistor used in the present work,Modification of correlation can even further imporve measurement accuracy.Since the thermistor is small and cheap,it is possible to apply this method to multi-Point velocity measurement with a low disturbance to the flow field.
Cluster-based statistics for brain connectivity in correlation with behavioral measures.
Directory of Open Access Journals (Sweden)
Cheol E Han
Full Text Available Graph theoretical approaches have successfully revealed abnormality in brain connectivity, in particular, for contrasting patients from healthy controls. Besides the group comparison analysis, a correlational study is also challenging. In studies with patients, for example, finding brain connections that indeed deepen specific symptoms is interesting. The correlational study is also beneficial since it does not require controls, which are often difficult to find, especially for old-age patients with cognitive impairment where controls could also have cognitive deficits due to normal ageing. However, one of the major difficulties in such correlational studies is too conservative multiple comparison correction. In this paper, we propose a novel method for identifying brain connections that are correlated with a specific cognitive behavior by employing cluster-based statistics, which is less conservative than other methods, such as Bonferroni correction, false discovery rate procedure, and extreme statistics. Our method is based on the insight that multiple brain connections, rather than a single connection, are responsible for abnormal behaviors. Given brain connectivity data, we first compute a partial correlation coefficient between every edge and the behavioral measure. Then we group together neighboring connections with strong correlation into clusters and calculate their maximum sizes. This procedure is repeated for randomly permuted assignments of behavioral measures. Significance levels of the identified sub-networks are estimated from the null distribution of the cluster sizes. This method is independent of network construction methods: either structural or functional network can be used in association with any behavioral measures. We further demonstrated the efficacy of our method using patients with subcortical vascular cognitive impairment. We identified sub-networks that are correlated with the disease severity by exploiting diffusion
Sabouri, Shirin; Fazli, Ladan; Chang, Silvia D; Savdie, Richard; Jones, Edward C; Goldenberg, S Larry; Black, Peter C; Kozlowski, Piotr
2017-09-01
To determine the relationship between parameters measured from luminal water imaging (LWI), a new magnetic resonance imaging (MRI) T2 mapping technique, and the corresponding tissue composition in prostate. In all, 17 patients with prostate cancer were examined with a 3D multiecho spin echo sequence at 3T prior to undergoing radical prostatectomy. Maps of seven MR parameters, called N, T2-short , T2-long , Ashort , Along , geometric mean T2 time (gmT2 ), and luminal water fraction (LWF), were generated using nonnegative least squares (NNLS) analysis of the T2 decay curves. MR parametric maps were correlated to digitized whole-mount histology sections. Percentage area of tissue components, including luminal space, nuclei, and cytoplasm plus stroma, was measured on the histology sections by using color-based image segmentation. Spearman's rank correlation test was used to evaluate the correlation between MR parameters and the corresponding tissue components, with particular attention paid to the correlation between LWF and percentage area of luminal space. N, T2-short , Along , gmT2 , and LWF showed significant correlation (P correlation (P correlation was observed between LWF and luminal space (Spearman's coefficient of rank correlation = 0.75, P correlated with the fractional amount of luminal space in prostatic tissue. This result suggests that LWI can potentially be applied for evaluation of prostatic diseases in which the extent of luminal space differs between normal and abnormal tissues. 1 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:861-869. © 2017 International Society for Magnetic Resonance in Medicine.
Cross-Correlation by Single-bit Signal Processing for Ultrasonic Distance Measurement
Hirata, Shinnosuke; Kurosawa, Minoru Kuribayashi; Katagiri, Takashi
Ultrasonic distance measurement using the pulse-echo method is based on the determination of the time of flight of ultrasonic waves. The pulse-compression technique, in which the cross-correlation function of a detected ultrasonic wave and a transmitted ultrasonic wave is obtained, is the conventional method used for improving the resolution of distance measurement. However, the calculation of a cross-correlation operation requires high-cost digital signal processing. This paper presents a new method of sensor signal processing within the pulse-compression technique using a delta-sigma modulated single-bit digital signal. The proposed sensor signal processing method consists of a cross-correlation operation employing single-bit signal processing and a smoothing operation involving a moving average filter. The proposed method reduces the calculation cost of the digital signal processing of the pulse-compression technique.
Velocity Distribution Measurement Using Pixel-Pixel Cross Correlation of Electrical Tomography
Institute of Scientific and Technical Information of China (English)
DENGXiang; PENGLihui; YAODanya; ZHANGBaofen
2004-01-01
Electrical tomography (ET) provides a novel means of visualizing the internal behavior of twophase flow in industrial process. Using a dual-sensingplane Electrical resistance tomography (ERT) or Electrical capacitance tomography (ECT) system, the raw data of two different section images can be acquired synchronously and the two images reflecting the inner medium distribution respectively can also be reconstructed by using imaging algorithm. Further, the analysis of pixel-pixel cross correlation is able to be setup and the measurement of velocity distribution of two-phase flow could be achieved. The principle is described in the paper. The FFT algorithm for gray value computation and cross correlation function calculation is also introduced. Some experimental results of velocity distribution measurement using pixelpixel cross correlation in vertical slug flow are presented.
Measure of Information Content of Remotely Sensed Images Accounting for Spatial Correlation
Directory of Open Access Journals (Sweden)
ZHANG Ying
2015-10-01
Full Text Available A measure is proposed based on the information theory and geostatistics to evaluate information content in remotely sensed images. The method is based on the additive noise model and maximum mutual information.These factors affecting the information content have been taken into account, such as noise, spatial correlation and so on. It is suitable for measuring the information content in optical images that have robust spatial correlation with different land cover types. An experiment was performed on a Landsat TM image with three different kinds of land cover types (city, farmland and mountain. The result shows that city has the most information content. It also proves that there is a log positive correlation between information content and the variance of the images.
Institute of Scientific and Technical Information of China (English)
程传福; 刘曼; 滕树云; 宋洪胜; 陈建平; 徐至展
2003-01-01
A method for the extracting the correlation functions of random surfaces is proposed by using the image speckle intensity. Theoretically, we analyse the integral expression of average intensity of the image speckles, and compare it with the pair of Fourier-Bessel-transform-and-the-inversion of the exponential function of the height-height correlation function of the random surfaces. Then the algorithm is proposed numerically to complement the lacking Bessel function factor in the expression of the average speckle intensity, which changes the intensity data into the pair of the Fourier-Bessel-transform. Experimentally, we measure the average image speckle intensities versus the radius of the filtering aperture in the 4 f system and extract the height-height correlation function by using the proposed algorithm. The results of the practical measurements for three surface samples and the comparison with those by atomic force microscopy validate the feasibility of this method.
DEFF Research Database (Denmark)
Holstein, P; Lassen, N A
1980-01-01
The frequency of healing in subchronic ulcers in 66 feet in 62 patients with arterial occlusive disease was correlated with the systolic digital blood pressure (SDBP) and the systolic ankle blood pressure (SABP), both measured with a strain gauge, and with the skin perfusion pressure on the heel...... of healing correlated significantly with the three distal blood pressure parameters investigated, the closest correlation being with the SDBP measured at the final examination, i.e. just after healing of the ulcer or just before an inevitable major amputation. Of the 22 cases with SDBP below 20 mmHg only two...... and peripheral neuropathy were frequent in the diabetic group. The data show that the systolic digital blood pressure is a particularly valuable prognostic parameter....
Parker, Stephen R; Ivanov, Eugene N; Tobar, Michael E
2015-01-01
Weakly Interacting Slim Particles (WISPs), such as axions, are highly motivated dark matter candidates. The most sensitive experimental searches for these particles exploit WISP-to-photon conversion mechanisms and use resonant cavity structures to enhance the resulting power signal. For WISPs to constitute Cold Dark Matter their required masses correspond to photons in the microwave spectrum. As such, searches for these types of WISPs are primarily limited by the thermal cavity noise and the broadband first-stage amplifier noise. In this work we propose and then verify two cross-correlation measurement techniques for cavity-based WISP searches. These are two channel measurement schemes where the cross-spectrum is computed, rejecting uncorrelated noise sources while still retaining correlated signals such as those generated by WISPs. The first technique allows for the cavity thermal spectrum to be observed with an enhanced resolution. The second technique cross-correlates two individual cavity/amplifier system...
Scambos, Theodore A.; Dutkiewicz, Melanie J.; Wison, Jeremy C.; Bindschadler, Robert A.
1992-01-01
A high-resolution map of the velocity field of the central portion of Ice Stream E in West Antarctica, generated by the displacement-measuring technique, is presented. The use of cross-correlation software is found to be a significant improvement over previous manually based photogrammetric methods for velocity measurement, and is far more cost-effective than in situ methods in remote polar areas. A hue-intensity-saturation image of Ice Stream E and its velocity field is shown.
Measurement of noise and its correlation to performance and geometry of small aircraft propellers
Štorch Vít; Nožička Jiří; Brada Martin; Gemperle Jiří; Suchý Jakub
2016-01-01
A set of small model and UAV propellers is measured both in terms of aerodynamic performance and acoustic noise under static conditions. Apart from obvious correlation of noise to tip speed and propeller diameter the influence of blade pitch, blade pitch distribution, efficiency and shape of the blade is sought. Using the measured performance data a computational model for calculation of aerodynamic noise of propellers will be validated. The range of selected propellers include both propeller...
Oxygen optodes as fast sensors for eddy correlation measurements in aquatic systems
DEFF Research Database (Denmark)
Chipman, Lindsay; Huettel, Markus; Berg, Peter
2012-01-01
The aquatic eddy-correlation technique can be used to noninvasively determine the oxygen exchange across the sediment-water interface by analyzing the covariance of vertical flow velocity and oxygen concentration in a small measuring volume above the sea bed. The method requires fast sensors that...
DEFF Research Database (Denmark)
Wu, Shengjun; Poulsen, Uffe Vestergaard; Mølmer, Klaus
2009-01-01
We consider the classical correlations that two observers can extract by measurements on a bipartite quantum state and we discuss how they are related to the quantum mutual information of the state. We show with several examples how complementarity gives rise to a gap between the quantum and the ...... in the deterministic quantum computation with one quantum bit....
The relation between Pearson’s correlation coefficient r and Salton’s cosine measure
Egghe, L.; Leydesdorff, L.
2009-01-01
The relation between Pearson's correlation coefficient and Salton's cosine measure is revealed based on the different possible values of the division of the L1-norm and the L2-norm of a vector. These different values yield a sheaf of increasingly straight lines which together form a cloud of points,
The relation between Pearson’s correlation coefficient r and Salton’s cosine measure
Egghe, L.; Leydesdorff, L.
2009-01-01
The relation between Pearson's correlation coefficient and Salton's cosine measure is revealed based on the different possible values of the division of the L1-norm and the L2-norm of a vector. These different values yield a sheaf of increasingly straight lines which together form a cloud of points,
Top quark pair charge asymmetry and spin correlation measurements [CMS speaker
Chwalek, Thorsten
2016-01-01
We give an overview over charge asymmetry and spin correlation measurements in top quark pair production. The presented analyses use data collected with the ATLAS and CMS detectors at a center-of-mass energy of 8TeV. Events with either dileptonic or semileptonic top quark pair decays are analyzed. All results are comparable with the predictions by the standard model.
Ochoa, Kelly; Nunez, Jeranil; Wang, Vincent J
2015-09-01
Measurement of peak expiratory flow (PEF) is recommended in the assessment of patients with asthma. However, the use of PEF involves multiple barriers, which have limited its use. Phonospirometry, as assessed by a novel Los Angeles phonospirometry technique, has shown good correlation to standard PEF measurements in a pilot study on symptomatic patients with asthma. We sought to develop a normogram for phonospirometry, and to validate the PEF normogram. A convenience sample of asymptomatic children ages 3-17 years old was approached for participation in the Emergency Department. Sample size calculations determined that at least 30 children per age group (n = 450) were needed. Children were asked to perform PEF measurements and phonospirometry, measured as the length of time (in s) the child was able to chant "lalala" in a single breath. 510 children were enrolled. Spearman's rho between PEF and phonospirometry was 0.722. Phonospirometry correlated with both age and height, with a Spearman rho of 0.697 and 0.696, respectively. This was slightly lower than the correlation of PEF with age and height with Spearman rhos of 0.877 and 0.902, respectively. A normogram was developed for phonospirometry based on age and height. This study determined normal value ranges for the Los Angeles phonospirometry technique for age and height, and also showed that the technique has good correlation with PEF. This technique may be used to assess a pediatric patient with an acute asthma exacerbation.
Eddy-correlation measurements above a maize crop using a simple cruciform hot-wire anemometer
Bottemanne, F.A.
1979-01-01
For measurements of the vertical transport of heat and momentum in the turbulent and slightly unstable boundary layer above a maize crop eddy-correlation techniques were applied. In addition to a vertical Gill-propellor anemometer and a Gill-propellor bivane, a cruciform hot-wire probe, mounted on a
Gaspard, Dany; Kass, Jonathan; Akers, Stephen; Hunter, Krystal; Pratter, Melvin
2017-08-08
Patient-reported dyspnea plays a central role in assessing cardiopulmonary disease. There is little evidence, however, that dyspnea correlates with objective exercise capacity measurements. If the correlation is poor, dyspnea as a proxy for objective assessment may be misleading. To compare patient's perception of dyspnea with maximum oxygen uptake (MaxVO2) during cardiopulmonary exercise testing (CPET). Fifty patients undergoing CPET for dyspnea evaluation were studied prospectively. Dyspnea assessment was measured by a metabolic equivalent of task (METs) table, Mahler Dyspnea Index, Borg Index, number of blocks walked, and flights of stairs climbed before stopping due to dyspnea. These descriptors were compared to MaxVO2. MaxVO2 showed low correlation with METs table (r = 0.388, p = 0.005) and no correlation with Mahler Index (r = 0.24, p = 0.093), Borg Index (r = -0.017, p = 0.905), number of blocks walked (r = 0.266, p = 0.077) or flights of stairs climbed (r = 0.188, p = 0.217). When adjusted for weight (maxVO2/kg), there was significant correlation between MaxVO2 and METs table (r = 0.711, p Max VO2 and the assessment methods, while patients with BMI > 30 had moderate correlation between MaxVO2 and METs table (r = 0.568, p = 0.002). Patient-reported dyspnea correlates poorly with MaxVO2 and fails to predict exercise capacity. Reliance on reported dyspnea may result in suboptimal categorization of cardiopulmonary disease severity.
Koor, Behrooz Ebrahimzadeh; Nakhaie, Mohammad Reza; Babaie, Saied
2015-01-01
One of the most important problems in patients on hemodialysis (HD) is chronic malnutrition. This study is aimed to assess the prevalence of malnutrition using a subjective global assessment (SGA) in HD patients referred to the Valie ASR Hospital, Arak, Iran. In this descriptive analysis study, 190 HD patients were selected with random sampling. SGA and anthropometric and biochemical measurements were assessed in all patients. Data were analyzed with the Chi-square and t-tests and Pearson correlation coefficient. P correlation of SGA score with patient's weight (r = -0.147) and patient's body mass index (BMI) (r = -0.238). Also, it correlated significantly with duration of dialysis treatment (years) (r = 0.404). The SGA score showed a significant negative correlation with mid-arm circumference (MAC) (r = - 0.152). No significant correlation was found between SGA score and mid-arm muscle area. Our study showed that >50% of patients on maintenance HD had mild or moderate malnutrition. There was no case of severe malnutrition. Duration of dialysis treatment and some anthropometric indices (weight, BMI and MAC) also showed a significant correlation with SGA score, which are important to determine the nutritional status of HD patients.
The classical correlation limits the ability of the measurement-induced average coherence
Zhang, Jun; Yang, Si-ren; Zhang, Yang; Yu, Chang-shui
2017-01-01
Coherence is the most fundamental quantum feature in quantum mechanics. For a bipartite quantum state, if a measurement is performed on one party, the other party, based on the measurement outcomes, will collapse to a corresponding state with some probability and hence gain the average coherence. It is shown that the average coherence is not less than the coherence of its reduced density matrix. In particular, it is very surprising that the extra average coherence (and the maximal extra average coherence with all the possible measurements taken into account) is upper bounded by the classical correlation of the bipartite state instead of the quantum correlation. We also find the sufficient and necessary condition for the null maximal extra average coherence. Some examples demonstrate the relation and, moreover, show that quantum correlation is neither sufficient nor necessary for the nonzero extra average coherence within a given measurement. In addition, the similar conclusions are drawn for both the basis-dependent and the basis-free coherence measure. PMID:28374756
Speciated Fine Particle Deposition to a Forest Canopy Measured by Eddy-Correlation Mass Spectrometry
Allen, J. O.; Gonzales, D. A.; Delia, A. E.; Jimenez, J. L.; Smith, K. A.; Canagaratna, M.; Jayne, J. T.; Worsnop, D. R.
2002-12-01
Dry deposition serves as an important mechanism for the removal particles from the atmosphere and for the addition of material to ecosystems. Here we report on measurements of aerosol particle deposition using eddy-correlation mass spectrometry data collected during the PROPHET 2001 study which was conducted at the University of Michigan Biological Station in a north Michigan forest. Aerosol composition was measured with fast time response using the recently-developed Aerodyne Aerosol Mass Spectrometer (AMS) (Jayne et~al.,~2000). In the AMS, particles were focused using an aerodynamic lens. The aerosol was then expanded into a vacuum where aerodynamic particle size is determined by particle time-of-flight. The particles were then directed to an oven where semi-volatile components were flash vaporized. Vaporized components were ionized by electron impaction and detected using a quadrupole mass spectrometer. Thus the response of characteristic ions from fine aerosol particles (particle diameter, Dp, = 0.04-1.5 μm) were measured with a frequency of 10 Hz. A sonic anemometer was also deployed to measure wind velocity with a frequency of 10 Hz. Fluxes of aerosol species were then calculated using the well-known eddy-correlation method as the covariance of the vertical wind speed and the species concentration. These results demonstrate the new eddy-correlation mass spectrometry technique for measuring directly speciated fine particle deposition rates.
Nursing workload measurement scales in Intensive Care Units. Correlation between NAS and NEMS
Directory of Open Access Journals (Sweden)
Montserrat Martínez Lareo
2011-11-01
Full Text Available The high costs of intensive care and the importance of patient safety and quality of care highlight the need to develop instrument to measure, as precisely as possible, nursing workload and staffing levels in intensive care. To assess the ideal staff number, we need instruments to measure the real nursing workload. The aim of this research is to compare two nursing workload measurement scales in Intensive Care Units, the Nursing Activities Score (NAS and Nine Equivalents of Nurse Manpower Use Score (NEMS. We also want to assess the staffing needs of our ICU. A descriptive correlational study will be performed in a mixed medical ICU. The sample will be composed of of a minimum of 70 patients. Data regarding individual patients and unit global workload will be recorded, measured both with the NEMS and NAS scales. The required nursing staff will be calculated according to the measured workload. Nursing staffing needs using both scales will be calculated and compared to the actual staff. A descriptive analysis of the variables will be performed, and the existing correlation between both scales will be assessed using the Pearson correlation coefficient. A Student-t test will be performed to determine the differences between the calculated staffing requirements and the actual nursing staff. All data analyses will be done using a statistical software.
Joint measurement of lensing–galaxy correlations using SPT and DES SV data
Energy Technology Data Exchange (ETDEWEB)
Baxter, E.; Clampitt, J.; Giannantonio, T.; Dodelson, S.; Jain, B.; Huterer, D.; Bleem, L.; Crawford, T.; Efstathiou, G.; Fosalba, P.; Kirk, D.; Kwan, J.; Sánchez, C.; Story, K.; Troxel, M. A.; Abbott, T. M. C.; Abdalla, F. B.; Armstrong, R.; Benoit-Lévy, A.; Benson, B.; Bernstein, G. M.; Bernstein, R. A.; Bertin, E.; Brooks, D.; Carlstrom, J.; Rosell, A. Carnero; Carrasco Kind, M.; Carretero, J.; Chown, R.; Crocce, M.; Cunha, C. E.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Evrard, A. E.; Fausti Neto, A.; Flaugher, B.; Frieman, J.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; de Haan, T.; Holder, G.; Honscheid, K.; Hou, Z.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lima, M.; March, M.; Marshall, J. L.; Martini, P.; Melchior, P.; Miller, C. J.; Miquel, R.; Mohr, J. J.; Nord, B.; Omori, Y.; Plazas, A. A.; Reichardt, C.; Romer, A. K.; Rykoff, E. S.; Sanchez, E.; Sevilla-Noarbe, I.; Sheldon, E.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Stark, A.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Walker, A. R.; Wechsler, R. H.
2016-07-04
We measure the correlation of galaxy lensing and cosmic microwave background lensing with a set of galaxies expected to trace the matter density field. The measurements are performed using pre-survey Dark Energy Survey (DES) Science Verification optical imaging data and millimetre-wave data from the 2500 sq. deg. South Pole Telescope Sunyaev–Zel'dovich (SPT-SZ) survey. The two lensing–galaxy correlations are jointly fit to extract constraints on cosmological parameters, constraints on the redshift distribution of the lens galaxies, and constraints on the absolute shear calibration of DES galaxy-lensing measurements. We show that an attractive feature of these fits is that they are fairly insensitive to the clustering bias of the galaxies used as matter tracers. The measurement presented in this work confirms that DES and SPT data are consistent with each other and with the currently favoured Λ cold dark matter cosmological model. It also demonstrates that joint lensing–galaxy correlation measurement considered here contains a wealth of information that can be extracted using current and future surveys.
Roga, W.; Spehner, D.; Illuminati, F.
2016-06-01
We investigate and compare three distinguished geometric measures of bipartite quantum correlations that have been recently introduced in the literature: the geometric discord, the measurement-induced geometric discord, and the discord of response, each one defined according to three contractive distances on the set of quantum states, namely the trace, Bures, and Hellinger distances. We establish a set of exact algebraic relations and inequalities between the different measures. In particular, we show that the geometric discord and the discord of response based on the Hellinger distance are easy to compute analytically for all quantum states whenever the reference subsystem is a qubit. These two measures thus provide the first instance of discords that are simultaneously fully computable, reliable (since they satisfy all the basic Axioms that must be obeyed by a proper measure of quantum correlations), and operationally viable (in terms of state distinguishability). We apply the general mathematical structure to determine the closest classical-quantum state of a given state and the maximally quantum-correlated states at fixed global state purity according to the different distances, as well as a necessary condition for a channel to be quantumness breaking.
Measuring Distance Ratios with CMB-Galaxy Lensing Cross-correlations
Das, Sudeep; 10.1103/PhysRevD.79.043509
2009-01-01
We propose a method for cosmographic measurements by combining gravitational lensing of the cosmic microwave background (CMB) with cosmic shear surveys. We cross-correlate the galaxy counts in the lens plane with two different source planes: the CMB at $z \\sim 1100$ and galaxies at an intermediate redshift. The ratio of the galaxy count/CMB lensing cross-correlation to the galaxy count/galaxy lensing cross correlation is shown to be a purely geometric quantity, depending only on the distribution function of the source galaxies. By combining Planck, ADEPT and LSST the ratio can be measured to $\\sim 4%$ accuracy, whereas a future polarization based experiment like CMBPOL can make a more precise ($\\sim 1%$) measurement. For cosmological models where the curvature and the equation of state parameter are allowed to vary, the direction of degeneracy defined by the measurement of this ratio is different from that traced out by Baryon Acoustic Oscillation (BAO) measurements. Combining this method with the stacked clu...
Tsai, Miao-Yu
2017-04-15
The concordance correlation coefficient (CCC) is a commonly accepted measure of agreement between two observers for continuous responses. This paper proposes a generalized estimating equations (GEE) approach allowing dependency between repeated measurements over time to assess intra-agreement for each observer and inter- and total agreement among multiple observers simultaneously. Furthermore, the indices of intra-, inter-, and total agreement through variance components (VC) from an extended three-way linear mixed model (LMM) are also developed with consideration of the correlation structure of longitudinal repeated measurements. Simulation studies are conducted to compare the performance of the GEE and VC approaches for repeated measurements from longitudinal data. An application of optometric conformity study is used for illustration. In conclusion, the GEE approach allowing flexibility in model assumptions and correlation structures of repeated measurements gives satisfactory results with small mean square errors and nominal 95% coverage rates for large data sets, and when the assumption of the relationship between variances and covariances for the extended three-way LMM holds, the VC approach performs outstandingly well for all sample sizes. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.
Joint measurement of lensing-galaxy correlations using SPT and DES SV data
Baxter, E.; Clampitt, J.; Giannantonio, T.; Dodelson, S.; Jain, B.; Huterer, D.; Bleem, L.; Crawford, T.; Efstathiou, G.; Fosalba, P.; Kirk, D.; Kwan, J.; Sánchez, C.; Story, K.; Troxel, M. A.; Abbott, T. M. C.; Abdalla, F. B.; Armstrong, R.; Benoit-Lévy, A.; Benson, B.; Bernstein, G. M.; Bernstein, R. A.; Bertin, E.; Brooks, D.; Carlstrom, J.; Rosell, A. Carnero; Carrasco Kind, M.; Carretero, J.; Chown, R.; Crocce, M.; Cunha, C. E.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Evrard, A. E.; Fausti Neto, A.; Flaugher, B.; Frieman, J.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; de Haan, T.; Holder, G.; Honscheid, K.; Hou, Z.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lima, M.; March, M.; Marshall, J. L.; Martini, P.; Melchior, P.; Miller, C. J.; Miquel, R.; Mohr, J. J.; Nord, B.; Omori, Y.; Plazas, A. A.; Reichardt, C.; Romer, A. K.; Rykoff, E. S.; Sanchez, E.; Sevilla-Noarbe, I.; Sheldon, E.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Stark, A.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Walker, A. R.; Wechsler, R. H.
2016-10-01
We measure the correlation of galaxy lensing and cosmic microwave background lensing with a set of galaxies expected to trace the matter density field. The measurements are performed using pre-survey Dark Energy Survey (DES) Science Verification optical imaging data and millimetre-wave data from the 2500 sq. deg. South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey. The two lensing-galaxy correlations are jointly fit to extract constraints on cosmological parameters, constraints on the redshift distribution of the lens galaxies, and constraints on the absolute shear calibration of DES galaxy-lensing measurements. We show that an attractive feature of these fits is that they are fairly insensitive to the clustering bias of the galaxies used as matter tracers. The measurement presented in this work confirms that DES and SPT data are consistent with each other and with the currently favoured Λ cold dark matter cosmological model. It also demonstrates that joint lensing-galaxy correlation measurement considered here contains a wealth of information that can be extracted using current and future surveys.
Laporte, Catherine; Arbel, Tal
2008-01-01
In freehand 3-D ultrasound (US), the relative positions of US images are usually measured using a position tracking device despite its cumbersome nature. The probe trajectory can instead be estimated from image data, using registration techniques to recover in-plane motion and speckle decorrelation to recover out-of-plane transformations. The relationship between speckle decorrelation and elevational separation is typically represented by a single curve, estimated from calibration data. Distances read off such a curve are corrupted by bias and uncertainty, and only provide an absolute estimate of elevational displacement. This paper presents a probabilistic model of the relationship between correlation measurements and elevational separation. This representation captures the skewed distribution of distance estimates based on high correlations and the uncertainties attached to each measurement. Multiple redundant correlation measurements can then be integrated within a maximum likelihood estimation framework. This paper also introduces a new method based on the traveling salesman problem for resolving sign ambiguities in data sets resulting from nonmonotonic probe motion and frame intersections. Experiments with real and synthetic US data show that by combining these new methods, out-of-plane US probe motion is recovered with improved accuracy over baseline methods using a deterministic model and fewer measurements.
Application of Digital Image Correlation to Measurement of Packaging Material Mechanical Properties
Directory of Open Access Journals (Sweden)
Jian-Wei Zhou
2013-01-01
Full Text Available Among various packaging materials, papers and polymer plastics are the most common due to their light weights, low costs, and other advantages. However, their mechanical properties are difficult to measure precisely because of their softness. To overcome the difficulty, a new measure instrument prototype is proposed based on an optical method known as the digital image correlation (DIC. Experiments are designed to apply the DIC to measure mechanical properties of flexible packaging materials, including the stress-strain relationship, the Poisson ratio, the coefficient of heat expansion, the creep deformation, and the top-pressure deformation of corrugated box. In addition, the low frequency vibration of package is simulated, and the vibration frequencies are measured by DIC. Results obtained in the experiments illustrate the advantages of the DIC over traditional methods: noncontact, no reinforced effect, high precision over entire area, wide measurement range, and good measurement stability.
Jizan, Iman; Xiong, Chunle; Collins, Matthew J; Choi, Duk-Yong; Chae, Chang Joon; Liscidini, Marco; Steel, M J; Eggleton, Benjamin J; Clark, Alex S
2014-01-01
The growing requirement for photon pairs with specific spectral correlations in quantum optics experiments has created a demand for fast, high resolution and accurate source characterization. A promising tool for such characterization uses the classical stimulated process, in which an additional seed laser stimulates photon generation yielding much higher count rates, as recently demonstrated for a $\\chi^{(2)}$ integrated source in A.~Eckstein \\emph{et al.}, Laser Photon. Rev. \\textbf{8}, L76 (2014). In this work we extend these results to $\\chi^{(3)}$ sources, demonstrating spectral correlation measurements via stimulated four-wave mixing for the first time in a integrated optical waveguide, namely a silicon nanowire. We directly confirm the speed-up due to higher count rates and demonstrate that additional resolution can be gained when compared to traditional coincidence measurements. As pump pulse duration can influence the degree of spectral entanglement, all of our measurements are taken for two differen...
Tensor Correlations Measured in 3He(e,e'pp)n
Baghdasaryan, H; Laget, J M; Adhikari, K P; Aghasyan, M; Amarian, M; Anghinolfi, M; Avakian, H; Ball, J; Battaglieri, M; Bedlinskiy, I; Berman, B L; Biselli, A S; Bookwalter, C; Briscoe, W J; Brooks, W K; B?ultmann, S; Burkert, V D; Carman, D S; Crede, V; D'Angelo, A; Daniel, A; Dashyan, N; DeVita, R; DeSanctis, E; Deur, A; Dey, B; Dickson, R; Djalali, C; Dodge, G E; Doughty, D; Dupre, R; Egiyan, H; Alaoui, A El; Fassi, L El; Eugenio, P; Fegan, S; Gabrielyan, M Y; Gilfoyle, G P; Giovanetti, K L; Gohn, W; Gothe, R W; Griffioen, K A; Guidal, M; Guo, L; Gyurjyan, V; Hakobyan, H; Hanretty, C; Hyde, C E; Hicks, K; Holtrop, M; Ilieva, Y; Ireland, D G; Joo, K; Keller, D; Khandaker, M; Khetarpal, P; Kim, A; Kim, W; Klein, A; Klein, F J; Konczykowski, P; Kubarovsky, V; Kuhn, S E; Kuleshov, S V; Kuznetsov, V; Kvaltine, N D; Livingston, K; Lu, H Y; MacGregor, I J D; Markov, N; Mayer, M; McAndrew, J; McKinnon, B; Meyer, C A; Mikhailov, K; Mokeev, V; Moreno, B; Moriya, K; Morrison, B; Moutarde, H; Munevar, E; Nadel-Turonski, P; Nepali, C; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Paremuzyan, R; Park, K; Park, S; Pasyuk, E; Pereira, S Anefalos; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Protopopescu, D; Ricco, G; Ripani, M; Rosner, G; Rossi, P; Sabati?e, F; Salgado, C; Schumacher, R A; Seraydaryan, H; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Taiuti, M; Tang, W; Taylor, C E; Tedeschi, D J; Ungaro, M; Vineyard, M F; Voutier, E; Watts, D P; Weygand, D P; Wood, M H; Zhao, B; Zhao, Z W
2010-01-01
We have measured the 3He(e,e'pp)n reaction at an incident energy of 4.7 GeV over a wide kinematic range. We identified spectator correlated pp and pn nucleon pairs using kinematic cuts and measured their relative and total momentum distributions. This is the first measurement of the ratio of pp to pn pairs as a function of pair total momentum, $p_{tot}$. For pair relative momenta between 0.3 and 0.5 GeV/c, the ratio is very small at low $p_{tot}$ and rises to approximately 0.5 at large $p_{tot}$. This shows the dominance of tensor over central correlations at this relative momentum.
Tensor Correlations Measured in 3He(e,e'pp)n
Energy Technology Data Exchange (ETDEWEB)
Baghdasaryan, H; Weinstein, L B; Adhikari, K P; Aghasyan, K P; Amarian, M; Anghinolfi, M; Avakian, H; Ball, J; Battaglieri, M; Bedlinskiy, I; Berman, B L; Biselli, A S; Bookwalter, C; Briscoe, W J; Brooks, W K; Boltmann, S; Burkert, V D; Carman, D S; Crede, V; D& #x27; Angelo, A; Daniel, A; Dashyan, N; DeVita, R; DeSanctis, E; Deur, A; Dey, B; Dickson, R; Djalali, C; Dodge, G E; Doughty, D; Dupre, R; Egiyan, H; El Alaoui, A; El Fassi, L; Eugenio, P; Fegan, S; Gabrielyan, M Y; Gilfoyle, G P; Giovanetti, K L; Gohn, W; Gothe, R W; Griffioen, K A; Guidal, M; Guo, L; Gyurjyan, V; Hakobyan, H; Hanretty, C; Hyde, C E; Hicks, K; Holtrop, M; Ilieva, Y; Ireland, D G; Joo, K; Keller, D; Khandaker, M; Khetarpal, P; Kim, A; Kim, W; Klein, A; Klein, F J; Konczykowski, P; Kubarovsky, V; Kuhn, S E; Kuleshov, S V; Kuznetsov, V; Kvaltine, N D; Livingston, K; Lu, H Y; MacGregor, I.J.D.; Markov, N; Mayer, M; McAndrew, J; McKinnon, B; Meyer, C A; Mikhailov, K; Mokeev, V; Moreno, B; Moriya, K; Morrison, B; Moutarde, H; Munevar, E; Nadel-Turonski, P; Nepali, C; Niccolai, S; Niculescu, G; Niculescu, I; Osipenko, M; Ostrovidov, A I; Paremuzyan, R; Park, K; Park, S; Pasyuk, E; Anefalos Pereira, S; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Protopopescu, D; Ricco, G; Ripani, M; Rosner, G; Rossi, P; Sabatie, F; Salgado, C; Schumacher, R A; Seraydaryan, H; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Stoler, P; Strauch, S; Taiuti, M; Tang, W; Taylor, C E; Tedeschi, D J; Ungaro, M; Vineyard, M F; Voutier, E; Watts, D P; Weygand, D P; Wood, M H; Zhao, B; Zhao, Z W
2010-11-01
We have measured the 3He(e,e'pp)n reaction at an incident energy of 4.7 GeV over a wide kinematic range. We identified spectator correlated pp and pn nucleon pairs by using kinematic cuts and measured their relative and total momentum distributions. This is the first measurement of the ratio of pp to pn pairs as a function of pair total momentum ptot. For pair relative momenta between 0.3 and 0.5 GeV/c, the ratio is very small at low ptot and rises to approximately 0.5 at large ptot. This shows the dominance of tensor over central correlations at this relative momentum.
Validation of MIPAS-ENVISAT by Correlative Measurements of MIPAS-STR
Keim, C.; Blom, C. E.; von der Gathen, P.; Gulde, T.; Höpfner, M.; Liu, G. Y.; Oulanovski, A.; Piesch, C.; Ravegnani, F.; Sartorius, C.; Schlager, H.; Volk, C. M.
2004-08-01
We report on the validation of profiles from the MIPAS-Envisat on-line processor of ESA version 4.61 with correlative measurements derived from MIPASSTR onboard the high-altitude aircraft M55-Geophysica. The validation is made for the July 22, 2002, orbit 2051 in the region of the campaign base in Forlí, Italy [1] and for several orbits in February / March 2003 around Kiruna, northern Sweden. This paper includes a careful comparison of the MIPASSTR data with O3 sondes and with in-situ measurements from the Geophysica obtained during ascent, descent and occasional dives. To obtain accurate N2O and CH4 profiles close to the MIPAS-Envisat tangent points we used the MIPAS-STR measurements of CFC-11 and CFC-12 and correlations [2] obtained by the HAGAR instrument.
Wallman, Joel J
2011-01-01
Quantum theory allows for correlations between the outcomes of distant measurements that are inconsistent with any locally causal theory, as demonstrated by the violation of a Bell inequality. Typical demonstrations of these correlations require careful alignment between the measurements, which requires distant parties to share a reference frame. Here, we prove, following a numerical observation by Shadbolt et al., that if two parties share a Bell state and each party randomly chooses three orthogonal measurements, then the parties will always violate a Bell inequality. Furthermore, we prove that this probability is highly robust against local depolarizing noise, in that small levels of noise only decrease the probability of violating a Bell inequality by a small amount. We also show that generalizing to N parties increases the robustness against noise. These results improve on previous ones that only allowed a high probability of violating a Bell inequality for large numbers of parties.
Measurement of Polarization and Triple-Product Correlations in B -> phi K^* Decays
Abe, K
2004-01-01
We present a measurement of the decay amplitudes and triple-product correlations in B -> phi K^* decays based on 140 fb^-1 of data recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB e^+ e^- storage ring. The decay amplitudes for the different phi K^* helicity states are measured from the angular distributions of final state particles in the transversity basis. The longitudinal and transverse complex amplitude moduli and angles are |A_0|^2 = 0.51 +- 0.06 +- 0.04, |A_perp|^2 = 0.24 +- 0.06 +- 0.03, arg(A_parallel) = -2.21 +- 0.22 +- 0.05 rad, and arg(A_perp) = 0.72 +- 0.21 +- 0.06 rad. The T-violating asymmetries through triple-product correlations are measured to be consistent with zero.
Quantized correlation coefficient for measuring reproducibility of ChIP-chip data.
Peng, Shouyong; Kuroda, Mitzi I; Park, Peter J
2010-07-27
Chromatin immunoprecipitation followed by microarray hybridization (ChIP-chip) is used to study protein-DNA interactions and histone modifications on a genome-scale. To ensure data quality, these experiments are usually performed in replicates, and a correlation coefficient between replicates is used often to assess reproducibility. However, the correlation coefficient can be misleading because it is affected not only by the reproducibility of the signal but also by the amount of binding signal present in the data. We develop the Quantized correlation coefficient (QCC) that is much less dependent on the amount of signal. This involves discretization of data into set of quantiles (quantization), a merging procedure to group the background probes, and recalculation of the Pearson correlation coefficient. This procedure reduces the influence of the background noise on the statistic, which then properly focuses more on the reproducibility of the signal. The performance of this procedure is tested in both simulated and real ChIP-chip data. For replicates with different levels of enrichment over background and coverage, we find that QCC reflects reproducibility more accurately and is more robust than the standard Pearson or Spearman correlation coefficients. The quantization and the merging procedure can also suggest a proper quantile threshold for separating signal from background for further analysis. To measure reproducibility of ChIP-chip data correctly, a correlation coefficient that is robust to the amount of signal present should be used. QCC is one such measure. The QCC statistic can also be applied in a variety of other contexts for measuring reproducibility, including analysis of array CGH data for DNA copy number and gene expression data.
Cooperative terrain model acquisition by two point-robots in planar polygonal terrains
Energy Technology Data Exchange (ETDEWEB)
Rao, N.S.V.; Protopopescu, V.
1994-11-29
We address the model acquisition problem for an unknown terrain by a team of two robots. The terrain may be cluttered by a finite number of polygonal obstacles with unknown shapes and positions. The robots are point-sized and equipped with visual sensors which acquire all visible parts of the terrain by scanning from their locations. The robots communicate with each other via wireless connection. The performance is measured by the number of the sensor (scan) operations which are assumed to be the most time-consuming/expensive of all the robot operations. We employ the restricted visibility graph methods in a hierarchiacal setup. For terrains with convex obstacles, the sensing time can be halved compared to a single robot implementation. For terrains with concave corners, the performance of the algorithm depends on the number of concave regions and their depths. A hierarchical decomposition of the restricted visibility graph into 2-connected components and trees is considered. Performance for the 2-robot team is expressed in terms of sizes of 2-connected components, and the sizes and diameters of the trees. The proposed algorithm and analysis can be applied to the methods based on Voronoi diagram and trapezoidal decomposition.
METHOD OF GREEN FUNCTIONS IN MATHEMATICAL MODELLING FOR TWO-POINT BOUNDARY-VALUE PROBLEMS
Directory of Open Access Journals (Sweden)
E. V. Dikareva
2015-01-01
Full Text Available Summary. In many applied problems of control, optimization, system theory, theoretical and construction mechanics, for problems with strings and nods structures, oscillation theory, theory of elasticity and plasticity, mechanical problems connected with fracture dynamics and shock waves, the main instrument for study these problems is a theory of high order ordinary differential equations. This methodology is also applied for studying mathematical models in graph theory with different partitioning based on differential equations. Such equations are used for theoretical foundation of mathematical models but also for constructing numerical methods and computer algorithms. These models are studied with use of Green function method. In the paper first necessary theoretical information is included on Green function method for multi point boundary-value problems. The main equation is discussed, notions of multi-point boundary conditions, boundary functionals, degenerate and non-degenerate problems, fundamental matrix of solutions are introduced. In the main part the problem to study is formulated in terms of shocks and deformations in boundary conditions. After that the main results are formulated. In theorem 1 conditions for existence and uniqueness of solutions are proved. In theorem 2 conditions are proved for strict positivity and equal measureness for a pair of solutions. In theorem 3 existence and estimates are proved for the least eigenvalue, spectral properties and positivity of eigenfunctions. In theorem 4 the weighted positivity is proved for the Green function. Some possible applications are considered for a signal theory and transmutation operators.
Studies of the dimensionality, correlates, and meaning of measures of the maximizing tendency
Directory of Open Access Journals (Sweden)
Hye Bin Rim
2011-08-01
Full Text Available This series of four studies was designed to clarify the underlying dimensionality and psychological well-being correlates of the major extant measures of the maximization tendency: the Maximization Scale (MS; Schwarz et al., 2002 and the Maximization Tendency Scale (MTS; Diab et al., 2008. Four studies using psychometric and factor analysis, item response theory (IRT, and an experimental manipulation all supported the following conclusions. The MS does measure three separate factors as postulated by its authors, but only two of them (alternative search and decisional difficulty are correlated with each other and (negatively with indices of well-being as postulated by the scale authors; high standards, the third factor, correlated strongly with the MTS, and both of these were strongly correlated with positive indices of well-being (optimism and happiness and functioning (e.g., self-esteem and self-efficacy. The high standards subscale and MTS were related to analytical decision making style, while alternative search and decision difficulty were related to the regret-based decision making style and to procrastination. The IRT analysis indicated serious weaknesses in the measurement capabilities of existing scales, and the findings of the experimental study confirmed that alternative search and decision difficulty are related to the maximization tendency while high standards and MTS are not. Implications for further research and scale development are discussed.
Measurement of long-range particle correlations in small systems with the ATLAS detector
Milov, Alexander; The ATLAS collaboration
2016-01-01
Study of particle correlations is an important instrument to understand the nature of relativistic heavy ion collisions. Using a wealth of new data available from the recent heavy ion runs of Large Hadron Collider at CERN it becomes possible to study particle correlations in different collisions systems under the same conditions. The results of several recent measurement performed by the ATLAS experiment are reviewed in this proceeding. Measurements are performed in various techniques in $pp$, $p+$Pb and PbPb collisions at the energies $\\sqrt{s_{_{\\rm{NN}}}}$, $\\sqrt{s}$ from 2.76 to 13 TeV. The results are compared between the systems having the same charged particle multiplicities in the final state, but different initial geometries. Results for multiplicity correlations, two-particle and muti-particle correlations measured in different techniques are presented and discussed. The goal of these comparison is to make further steps in understanding the nature of fluctuations observed in the small collisions sy...
Charonko, John J.; Vlachos, Pavlos P.
2013-06-01
Numerous studies have established firmly that particle image velocimetry (PIV) is a robust method for non-invasive, quantitative measurements of fluid velocity, and that when carefully conducted, typical measurements can accurately detect displacements in digital images with a resolution well below a single pixel (in some cases well below a hundredth of a pixel). However, to date, these estimates have only been able to provide guidance on the expected error for an average measurement under specific image quality and flow conditions. This paper demonstrates a new method for estimating the uncertainty bounds to within a given confidence interval for a specific, individual measurement. Here, cross-correlation peak ratio, the ratio of primary to secondary peak height, is shown to correlate strongly with the range of observed error values for a given measurement, regardless of flow condition or image quality. This relationship is significantly stronger for phase-only generalized cross-correlation PIV processing, while the standard correlation approach showed weaker performance. Using an analytical model of the relationship derived from synthetic data sets, the uncertainty bounds at a 95% confidence interval are then computed for several artificial and experimental flow fields, and the resulting errors are shown to match closely to the predicted uncertainties. While this method stops short of being able to predict the true error for a given measurement, knowledge of the uncertainty level for a PIV experiment should provide great benefits when applying the results of PIV analysis to engineering design studies and computational fluid dynamics validation efforts. Moreover, this approach is exceptionally simple to implement and requires negligible additional computational cost.
Measurement of ttbar Spin Correlation in ppbar Collisions Using the CDF II Detector at the Tevatron
al., T Aaltonen et
2010-01-01
The ttbar spin correlation at production is a fundamental prediction of QCD and a potentially incisive test of new physics coupled to top quarks. We measure the ttbar spin state in ppbar collisions at sqrt(s) = 1.96 TeV using 1001 candidate events in the lepton plus jets decay channel reconstructed in the CDF II detector. In the helicity basis, for a top-quark mass of 172.5 GeV/c^2, we find a spin correlation coefficient kappa = 0.60 +/- 0.50 (stat) +/- 0.16 (syst), consistent with the QCD prediction, kappa ~= 0.40.
Lebreton, A; Abram, I; Braive, R; Sagnes, I; Robert-Philip, I; Beveratos, A
2013-04-19
We present a novel experimental technique that can differentiate unequivocally between chaotic light and coherent light with amplitude fluctuations, and thus permits us to characterize unambiguously the output of a laser. This technique consists of measuring the second-order intensity cross correlation at the outputs of an unbalanced Michelson interferometer. It is applied to a chaotic light source and to the output of a semiconductor nanolaser whose "standard" intensity correlation function above threshold displays values compatible with a mixture of coherent and chaotic light. Our experimental results demonstrate that the output of such lasers is not partially chaotic but is indeed a coherent state with amplitude fluctuations.
Correlates of objectively measured physical activity in 5-6 year old preschool children
DEFF Research Database (Denmark)
Olesen, L G; Kristensen, P L; Korsholm, L;
2015-01-01
preschools. Percentage of total daily time spent in moderate and vigorously physical activity (MVPA) was measured using ActiGraph accelerometers over 5 preschool days and 2 days off. Thirty--nine potential correlates of child MVPA across 5 domains were tested for associations with gender specific MVPA......The aim of this study was to identify gender specific physical activity correlates in Danish preschool children. METHODS: Cross--sectional study in Odense, Denmark. The gender specific models were based on data from 174 boys and 177 girls, 5--6 years of age and enrolled in 40 randomly selected...
Lebreton, Armand; Braive, Rémy; Sagnes, Isabelle; Robert-Philip, Isabelle; Beveratos, Alexios
2013-01-01
We present a novel experimental technique that can differentiate unequivocally between chaotic light and coherent light with amplitude fluctuations, and thus permits to characterize unambiguously the output of a laser. This technique consists of measuring the second-order intensity cross-correlation at the outputs of an unbalanced Michelson interferometer. It is applied to a chaotic light source and to the output of a semiconductor nanolaser whose "standard" intensity correlation function above-threshold displays values compatible with a mixture of coherent and chaotic light. Our experimental results demonstrate that the output of such lasers is not partially chaotic but is indeed a coherent state with amplitude fluctuations.
Energy Technology Data Exchange (ETDEWEB)
Zhang, J.; Chowdhury, S.; Messac, A.; Hodge, B. M.
2013-08-01
This paper significantly advances the hybrid measure-correlate-predict (MCP) methodology, enabling it to account for variations of both wind speed and direction. The advanced hybrid MCP method uses the recorded data of multiple reference stations to estimate the long-term wind condition at a target wind plant site. The results show that the accuracy of the hybrid MCP method is highly sensitive to the combination of the individual MCP algorithms and reference stations. It was also found that the best combination of MCP algorithms varies based on the length of the correlation period.
Song repertoire size correlates with measures of body size in Eurasian blackbirds
DEFF Research Database (Denmark)
Hesler, Nana; Mundry, Roger; Sacher, Thomas;
2012-01-01
organisation. Here we investigated whether repertoire size in Eurasian blackbirds correlates with measures of body size, namely length of wing, 8th primary, beak and tarsus. So far, very few studies have investigated species with large repertoires and a flexible song organisation in this context. We found...... positive correlations, meaning that larger males had larger repertoires. Larger males may have better fighting abilities and, thus, advantages in territorial defence. Larger structural body size may also reflect better conditions during early development. Therefore, under the assumption that body size...
What does the correlation dimension of the human heart rate measure?
Sakki, M; Vainu, M; Laan, M
2001-01-01
It is shown that for the heart rate variability, finite values of the correlation dimension D (calculated by the Grassberger-Procaccia algorithm) cannot be considered as an evidence for a deterministic chaos inside the heart. Finiteness of D is explained by finite resolving power of the recording apparatus. The correlation dimension depends both on the short-time variability of the heart rhythm, and on the resolving power of the electrocardiogram. In principle, it can be used as a certain measure of short-time variability of the signal, but its diagnostic value on test groups was negligible.
Rogers, Jeremy D.
2016-03-01
Numerous methods have been developed to quantify the light scattering properties of tissue. These properties are of interest in diagnostic and screening applications due to sensitivity to changes in tissue ultrastructure and changes associated with disease such as cancer. Tissue is considered a weak scatterer because that the mean free path is much larger than the correlation length. When this is the case, all scattering properties can be calculated from the refractive index correlation function Bn(r). Direct measurement of Bn(r) is challenging because it requires refractive index measurement at high resolution over a large tissue volume. Instead, a model is usually assumed. One particularly useful model, the Whittle-Matern function includes several realistic function types such as mass fractal and exponential. Optical scattering properties for weakly scattering media can be determined analytically from Bn(r) by applying the Rayleigh-Gans-Debye (RGD) or Born Approximation, and so measured scattering properties are used to fit parameters of the model function. Direct measurement of Bn(r) would provide confirmation that the function is a good representation of tissue or help in identifying the length scale at which changes occur. The RGD approximation relates the scattering phase function to the refractive index correlation function through a Fourier transform. This can be inverted without approximation, so goniometric measurement of the scattering can be converted to Bn(r). However, geometric constraints of the measurement of the phase function, angular resolution, and wavelength result in a band limited measurement of Bn(r). These limits are discussed and example measurements are described.
Directory of Open Access Journals (Sweden)
Andrei V. Obukhovskiĭ
2003-05-01
Full Text Available We consider second-order differential inclusions on a Riemannian manifold with lower semicontinuous right-hand sides. Several existence theorems for solutions of two-point boundary value problem are proved to be interpreted as controllability of special mechanical systems with control on nonlinear configuration spaces. As an application, a statement of controllability under extreme values of controlling force is obtained.
Caballero-Águila, R.; Hermoso-Carazo, A.; Linares-Pérez, J.
2015-02-01
In this paper, the optimal least-squares state estimation problem is addressed for a class of discrete-time multisensor linear stochastic systems with state transition and measurement random parameter matrices and correlated noises. It is assumed that at any sampling time, as a consequence of possible failures during the transmission process, one-step delays with different delay characteristics may occur randomly in the received measurements. The random delay phenomenon is modelled by using a different sequence of Bernoulli random variables in each sensor. The process noise and all the sensor measurement noises are one-step autocorrelated and different sensor noises are one-step cross-correlated. Also, the process noise and each sensor measurement noise are two-step cross-correlated. Based on the proposed model and using an innovation approach, the optimal linear filter is designed by a recursive algorithm which is very simple computationally and suitable for online applications. A numerical simulation is exploited to illustrate the feasibility of the proposed filtering algorithm.
Directory of Open Access Journals (Sweden)
Hyeong-Moo Shin
Full Text Available The work addresses current knowledge gaps regarding causes for correlations between environmental and biomarker measurements and explores the underappreciated role of variability in disaggregating exposure attributes that contribute to biomarker levels. Our simulation-based study considers variability in environmental and food measurements, the relative contribution of various exposure sources (indoors and food, and the biological half-life of a compound, on the resulting correlations between biomarker and environmental measurements. For two hypothetical compounds whose half-lives are on the order of days for one and years for the other, we generate synthetic daily environmental concentrations and food exposures with different day-to-day and population variability as well as different amounts of home- and food-based exposure. Assuming that the total intake results only from home-based exposure and food ingestion, we estimate time-dependent biomarker concentrations using a one-compartment pharmacokinetic model. Box plots of modeled R2 values indicate that although the R2 correlation between wipe and biological (e.g., serum measurements is within the same range for the two compounds, the relative contribution of the home exposure to the total exposure could differ by up to 20%, thus providing the relative indication of their contribution to body burden. The novel method introduced in this paper provides insights for evaluating scenarios or experiments where sample, exposure, and compound variability must be weighed in order to interpret associations between exposure data.
Directory of Open Access Journals (Sweden)
Raquel Caballero-Águila
2015-01-01
Full Text Available The distributed fusion state estimation problem is addressed for sensor network systems with random state transition matrix and random measurement matrices, which provide a unified framework to consider some network-induced random phenomena. The process noise and all the sensor measurement noises are assumed to be one-step autocorrelated and different sensor noises are one-step cross-correlated; also, the process noise and each sensor measurement noise are two-step cross-correlated. These correlation assumptions cover many practical situations, where the classical independence hypothesis is not realistic. Using an innovation methodology, local least-squares linear filtering estimators are recursively obtained at each sensor. The distributed fusion method is then used to form the optimal matrix-weighted sum of these local filters according to the mean squared error criterion. A numerical simulation example shows the accuracy of the proposed distributed fusion filtering algorithm and illustrates some of the network-induced stochastic uncertainties that can be dealt with in the current system model, such as sensor gain degradation, missing measurements, and multiplicative noise.
Measurement of the transverse spin correlations in the decay $Z \\rightarrow \\tau^+\\tau^-$
Barate, R; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Nief, J Y; Pietrzyk, B; Casado, M P; Chmeissani, M; Comas, P; Crespo, J M; Delfino, M C; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Miquel, R; Mir, L M; Orteu, S; Padilla, C; Park, I C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Alemany, R; Becker, U; Bazarko, A O; Bright-Thomas, P G; Cattaneo, M; Cerutti, F; Dissertori, G; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Hansen, J B; Harvey, J; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Lutters, G; Mato, P; Minten, Adolf G; Moneta, L; Pacheco, A; Pusztaszeri, J F; Ranjard, F; Rizzo, G; Rolandi, Luigi; Rousseau, D; Schlatter, W D; Schmitt, M; Schneider, O; Tejessy, W; Tomalin, I R; Wachsmuth, H W; Wagner, A; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Ferdi, C; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rosnet, P; Rossignol, J M; Fearnley, Tom; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Zachariadou, K; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Casper, David William; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Scarr, J M; Smith, K; Teixeira-Dias, P; Thompson, A S; Thomson, E; Thomson, F; Turnbull, R M; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Schmidt, M; Sommer, J; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Girone, M; Goodsir, S M; Martin, E B; Moutoussi, A; Nash, J; Sedgbeer, J K; Spagnolo, P; Stacey, A M; Williams, M D; Ghete, V M; Girtler, P; Kuhn, D; Rudolph, G; Betteridge, A P; Bowdery, C K; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Jones, R W L; Sloan, Terence; Williams, M I; Galla, A; Giehl, I; Greene, A M; Hoffmann, C; Jakobs, K; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Coyle, P; Diaconu, C A; Etienne, F; Konstantinidis, N P; Leroy, O; Motsch, F; Payre, P; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Aleppo, M; Ragusa, F; Berlich, R; Blum, Walter; Büscher, V; Dietl, H; Ganis, G; Gotzhein, C; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Stenzel, H; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Chen, S; Choi, Y; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Höcker, A; Jacholkowska, A; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Schune, M H; Simion, S; Tournefier, E; Veillet, J J; Videau, I; Zerwas, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Sanguinetti, G; Sciabà, A; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Venturi, A; Verdini, P G; Blair, G A; Bryant, L M; Chambers, J T; Gao, Y; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Maley, P; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Kelly, M S; Lehto, M H; Newton, W M; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Grupen, Claus; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Charles, E; Elmer, P; Ferguson, D P S; González, S; Greening, T C; Hayes, O J; Hu, H; Jin, S; McNamara, P A; Nachtman, J M; Nielsen, J; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, J; Wu Sau Lan; Wu, X; Yamartino, J M; Zobernig, G
1997-01-01
For tau leptons produced in e^+e^- -> tau^+ tau^- interactions there are, in addition to the longitudinal spin correlations, two independent transverse spin correlations associated with the transverse (within the production plane) and normal (to the production plane) polarization components. A measurement of the transverse-transverse and transverse-normal tau spin correlations in the decay Z -> tau^+ tau^-, C_{TT} and C_{TN}, is presented based on the aplanarity angle of the decay products of both tau leptons. Using 80 pb^{-1} of data collected by ALEPH on the peak of the Z resonance, the results are C_{TT} = 1.06 +- 0.13 (stat) +- 0.05 (syst), and C_{TN} = 0.08 +- 0.13 (stat) +- 0.04 (syst). These values are in agreement with the Standard Model predictions, C_{TT} = 0.99 and C_{TN} = -0.01.
Pairwise correlations via quantum discord and its geometric measure in a four-qubit spin chain
Directory of Open Access Journals (Sweden)
Abdel-Baset A. Mohamed
2013-04-01
Full Text Available The dynamic of pairwise correlations, including quantum entanglement (QE and discord (QD with geometric measure of quantum discord (GMQD, are shown in the four-qubit Heisenberg XX spin chain. The results show that the effect of the entanglement degree of the initial state on the pairwise correlations is stronger for alternate qubits than it is for nearest-neighbor qubits. This parameter results in sudden death for QE, but it cannot do so for QD and GMQD. With different values for this entanglement parameter of the initial state, QD and GMQD differ and are sensitive for any change in this parameter. It is found that GMQD is more robust than both QD and QE to describe correlations with nonzero values, which offers a valuable resource for quantum computation.
Aydin, Serdar; Bakar, Rabia Zehra; Arioğlu Aydin, Çağri; Ateş, Seda
2017-03-09
The aim of this study is to investigate the association of sexual functions with levator hiatus biometry measurements and levator ani muscle defect. In 62 heterosexual, sexually active premenopausal women without pelvic floor disorders or urinary incontinence, 3-dimensional transperineal ultrasound imaging was used. Two 3-dimensional volumes were recorded, one at rest and one on Valsalva maneuver. Levator biometry measurements and levator defect were evaluated in an axial plane. Sexual function was assessed by a validated questionnaire, Female Sexual Function Index (FSFI). The primary outcome measure was correlation of sexual functions with the levator hiatus area, transverse and anteroposterior diameters, levator ani muscle thickness, vaginal length, and changes in measurements with Valsalva and levator defect. Forty-two women (67.7%) had low total FSFI scores (<26.55). Levator defect rates were similar in female sexual dysfunction (7/42, 16.7%) and women without female sexual dysfunction (5/20, 25%). The FSFI was negatively and weakly correlated with Δhiatal anteroposterior diameter (r = -0.33, P < 0.009) in the study population. There was a weak and inverse correlation between Δhiatal anteroposterior diameter and arousal (r = -0.35, P < 0.002), desire (r = -0.38, P < 0.001), and orgasm (r = -0.33, P < 0.007). Pain and lubrication did not correlate with any measurement. Hiatal area and diameters at rest are not related to sexual functions. Changes in anteroposterior diameter of the levator hiatus during Valsalva, which may be a sign of pelvic floor laxity or levator muscle weakness, are weakly associated with sexual functions, particularly desire, arousal, and orgasm domains.
Hamilton, James C; Gregory, William A; Valentine, John B
2006-01-01
In this clinical study, DIAGNOdent (KaVo) was used to assess previously diagnosed carious lesions in the pits and fissures of first and second molars. The measurements from this device were correlated with the depth and volume of the cavity preparations that resulted from minimal intervention to remove occlusal carious lesions. Twenty-five patients, 18 years of age and older, who were previously scheduled for an occlusal restoration due to caries, were recruited and enrolled in this clinical study. These patients had 48 qualifying teeth without previous restorations, sealants or other carious lesions. The occlusal surface of each study tooth was cleaned utilizing ProphyFlex2 (KaVo). Two dentists separately traced the pit and fissure system of each tooth using DIAGNOdent for two 15-second periods each. The peak reading of each of the four measurements was recorded. An impression of the occlusal surface of each tooth was recorded with a polyvinyl siloxane bite registration material. The carious lesions were removed with an air abrasion unit employing a 0.015-inch nozzle opening utilizing minimal operative intervention. A low viscosity polyvinyl siloxane was used to take an impression of the cavity preparation impression, using the bite registration impression to form the occlusal surface of the preparation impression. The preparation impression volume was calculated from its weight, using the known density of the impression material. The greatest depth of the preparation was measured. The Pearson correlation coefficient was used to investigate any relationship between depth or volume of the preparation impression and the DIAGNOdent measurements. The correlation for preparation volume and maximum DIAGNOdent measurement was 0.191 (p = 0.189). Other logical subsets of cases also did not result in any statistically significant correlations between the DIAGNOdent readings and the depth or volume of the final cavity preparations.
Nguyen, Manh-Tu; Allain, Jean-Marc; Gharbi, Hakim; Desceliers, Christophe; Soize, Christian
2016-10-01
The implementation of the experimental methodology by optical measurements of mechanical fields, the development of a test bench, the specimen preparation, the experimental measurements, and the digital image correlation (DIC) method, have already been the object of research in the context of biological materials. Nevertheless, in the framework of the experimental identification of a mesoscopic stochastic model of the random apparent elasticity field, measurements of one specimen is required at both the macroscopic scale and the mesoscopic scale under one single loading. The nature of the cortical bone induces some difficulties, as no single speckled pattern technique is available for simultaneously obtaining the displacement at the macroscopic scale and at the mesoscopic scale. In this paper, we present a multiscale experimental methodology based on (i) an experimental protocol for one specimen of a cortical bone, (ii) its measuring bench, (iii) optical field measurements by DIC method, (iv) the experimental results, and (v) the multiscale experimental identification by solving a statistical inverse problem.
Effect of camera temperature variations on stereo-digital image correlation measurements
Pan, Bing
2015-11-25
In laboratory and especially non-laboratory stereo-digital image correlation (stereo-DIC) applications, the extrinsic and intrinsic parameters of the cameras used in the system may change slightly due to the camera warm-up effect and possible variations in ambient temperature. Because these camera parameters are generally calibrated once prior to measurements and considered to be unaltered during the whole measurement period, the changes in these parameters unavoidably induce displacement/strain errors. In this study, the effect of temperature variations on stereo-DIC measurements is investigated experimentally. To quantify the errors associated with camera or ambient temperature changes, surface displacements and strains of a stationary optical quartz glass plate with near-zero thermal expansion were continuously measured using a regular stereo-DIC system. The results confirm that (1) temperature variations in the cameras and ambient environment have a considerable influence on the displacements and strains measured by stereo-DIC due to the slightly altered extrinsic and intrinsic camera parameters; and (2) the corresponding displacement and strain errors correlate with temperature changes. For the specific stereo-DIC configuration used in this work, the temperature-induced strain errors were estimated to be approximately 30–50 με/°C. To minimize the adverse effect of camera temperature variations on stereo-DIC measurements, two simple but effective solutions are suggested.
Effect of camera temperature variations on stereo-digital image correlation measurements.
Pan, Bing; Shi, Wentao; Lubineau, Gilles
2015-12-01
In laboratory and especially non-laboratory stereo-digital image correlation (stereo-DIC) applications, the extrinsic and intrinsic parameters of the cameras used in the system may change slightly due to the camera warm-up effect and possible variations in ambient temperature. Because these camera parameters are generally calibrated once prior to measurements and considered to be unaltered during the whole measurement period, the changes in these parameters unavoidably induce displacement/strain errors. In this study, the effect of temperature variations on stereo-DIC measurements is investigated experimentally. To quantify the errors associated with camera or ambient temperature changes, surface displacements and strains of a stationary optical quartz glass plate with near-zero thermal expansion were continuously measured using a regular stereo-DIC system. The results confirm that (1) temperature variations in the cameras and ambient environment have a considerable influence on the displacements and strains measured by stereo-DIC due to the slightly altered extrinsic and intrinsic camera parameters; and (2) the corresponding displacement and strain errors correlate with temperature changes. For the specific stereo-DIC configuration used in this work, the temperature-induced strain errors were estimated to be approximately 30-50 με/°C. To minimize the adverse effect of camera temperature variations on stereo-DIC measurements, two simple but effective solutions are suggested.
Mitigating Systematic Errors in Angular Correlation Function Measurements from Wide Field Surveys
Morrison, Christopher Brian
2015-01-01
We present an investigation into the effects of survey systematics such as varying depth, point spread function (PSF) size, and extinction on the galaxy selection and correlation in photometric, multi-epoch, wide area surveys. We take the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS) as an example. Variations in galaxy selection due to systematics are found to cause density fluctuations of up to 10% for some small fraction of the area for most galaxy redshift slices and as much as 50% for some extreme cases of faint high-redshift samples. This results in correlations of galaxies against survey systematics of order $\\sim$1% when averaged over the survey area. We present an empirical method for mitigating these systematic correlations from measurements of angular correlation functions using weighted random points. These weighted random catalogs are estimated from the observed galaxy over densities by mapping these to survey parameters. We are able to model and mitigate the effect of systematic correl...
Correlations of MMPI factor scales with measures of the five factor model of personality.
Costa, P T; Busch, C M; Zonderman, A B; McCrae, R R
1986-01-01
Two recent item factor analyses of the Minnesota Multiphasic Personality Inventory (MMPI) classified the resulting factors according to a conceptual scheme offered by Norman's (1963) five factor model. The present article empirically evaluates those classifications by correlating MMPI factor scales with self-report and peer rating measures of the five factor model in a sample of 153 adult men and women. Both sets of predictions were generally supported, although MMPI factors derived in a normal sample showed closer correspondences with the five normal personality dimensions. MMPI factor scales were also correlated with 18 scales measuring specific traits within the broader domains of Neuroticism, Extraversion, and Openness. The nine Costa, Zonderman, McCrae, and Williams (1985) MMPI factor scales appear to give useful global assessments of four of the five factors; other instruments are needed to provide detailed information on more specific aspects of normal personality. The use of the five factor model in routine clinical assessment is discussed.
Institute of Scientific and Technical Information of China (English)
XIA Dunsheng; J. Bloemendal; R. C. Chiverrell; J. A. Dearing; JIN Ming
2004-01-01
A set of environmental magnetic parameters (i.e. magnetic susceptibility, χARM, IRMs, hysteresis loops and thermomagnetic curves) has been applied to two soil sections from SE Iceland. Results demonstrate that the main magnetic minerals in the tephras are ferrimagnetic minerals (e.g. magnetite) and canted antiferromagnetic minerals (e.g. haematite), with abundant paramagnetic material also present. Cross plots of Mrs/Ms vs. (B0)cr/(B0)c and χfd% vs. χARM/SIRM indicate that the main magnetic grain sizes in tephras are pseudo single domain (PSD) and multidomain (MD). Initial correlation of tephra layers was achieved, using all the measured magnetic parameters, by use of the multivariate statistical measures of Similarity Coefficient (SC) and Euclidean Distance (ED). This demonstrates that magnetic techniques can potentially assist in the identification and correlation of distal tephra.
High-dynamic-range cross-correlator for shot-to-shot measurement of temporal contrast
Kon, Akira; Nishiuchi, Mamiko; Kiriyama, Hiromitsu; Ogura, Koichi; Mori, Michiaki; Sakaki, Hironao; Kando, Masaki; Kondo, Kiminori
2017-01-01
The temporal contrast of an ultrahigh-intensity laser is a crucial parameter for laser plasma experiments. We have developed a multichannel cross-correlator (MCCC) for single-shot measurements of the temporal contrast in a high-power laser system. The MCCC is based on third-order cross-correlation, and has four channels and independent optical delay lines. We have experimentally demonstrated that the MCCC system achieves a high dynamic range of ˜1012 and a large temporal window of ˜1 ns. Moreover, we were able to measure the shot-to-shot fluctuations of a short-prepulse intensity at -26 ps and long-pulse (amplified spontaneous emission, ASE) intensities at -30, -450, and -950 ps before the arrival of the main pulse at the interaction point.
Time correlation measurements from extensive air showers detected by the EEE telescopes
Abbrescia, M; Fabbri, F L; Gnesi, I; Bressan, E; Tosello, F; Librizzi, F; Coccia, E; Paoletti, R; Yanez, G; Li, S; Votano, L; Scribano, A; Avanzini, C; Piragino, G; Perasso, L; Regano, A; Ferroli, R Baldini; De Gruttola, D; Sartorelli, G; Siddi, E; Cifarelli, L; Di Giovanni, A; Frolov, V; Serci, S; Selvi, M; Zouyevski, R; Dreucci, M; Squarcia, S; Righini, G C; Agocs, A; Zichichi, A; La Rocca, P; Pilo, F; Miozzi, S; Massai, M; Cicalo, C; D'Incecco, M; Panareo, M; Gemme, G; Garbini, M; Aiola, S; Riggi, F; Hatzifotiadou, D; Scapparone, E; Chiavassa, A; Maggiora, A; Bencivenni, G; Gustavino, C; Spandre, G; Taiuti, M; Williams, M C S; Bossini, E; De Pasquale, S
2013-01-01
Time correlated events due to cosmic muons from extensive air showers have been detected by means of telescope pairs of the EEE (Extreme Energy Events) Project array. The coincidence rate, properly normalized for detector acceptance, efficiency and altitude location, has been extracted as a function of the relative distance between the telescopes. The results have been also compared with additional measurements carried out by small scintillator detectors at various distances.
Time correlation measurements from extensive air showers detected by the EEE telescopes
Abbrescia, M.; Agocs, A.; Aiola, S.; Antolini, R.; Avanzini, C.; Baldini Ferroli, R.; Bencivenni, G.; Bossini, E.; Bressan, E.; Chiavassa, A.; Cicalò, C.; Cifarelli, L.; Coccia, E.; De Gruttola, D.; De Pasquale, S.; Di Giovanni, A.; D'Incecco, M.; Dreucci, M.; Fabbri, F. L.; Frolov, V.; Garbini, M.; Gemme, G.; Gnesi, I.; Gustavino, C.; Hatzifotiadou, D.; La Rocca, P.; Li, S.; Librizzi, F.; Maggiora, A.; Massai, M.; Miozzi, S.; Panareo, M.; Paoletti, R.; Perasso, L.; Pilo, F.; Piragino, G.; Regano, A.; Riggi, F.; Righini, G. C.; Sartorelli, G.; Scapparone, E.; Scribano, A.; Selvi, M.; Serci, S.; Siddi, E.; Spandre, G.; Squarcia, S.; Taiuti, M.; Tosello, F.; Votano, L.; Williams, M. C. S.; Yanez, G.; Zichichi, A.; Zouyevski, R.
2013-12-01
Time correlated events due to cosmic muons from extensive air showers have been detected by means of telescope pairs of the EEE (Extreme Energy Events) Project array. The coincidence rate, properly normalized for detector acceptance, efficiency and altitude location, has been extracted as a function of the relative distance between the telescopes. The results have been also compared with additional measurements carried out by small scintillator detectors at various distances.
O'Neill, George C.; Barratt, Eleanor L.; Hunt, Benjamin A. E.; Tewarie, Prejaas K.; Brookes, Matthew J.
2015-11-01
The human brain can be divided into multiple areas, each responsible for different aspects of behaviour. Healthy brain function relies upon efficient connectivity between these areas and, in recent years, neuroimaging has been revolutionised by an ability to estimate this connectivity. In this paper we discuss measurement of network connectivity using magnetoencephalography (MEG), a technique capable of imaging electrophysiological brain activity with good (~5 mm) spatial resolution and excellent (~1 ms) temporal resolution. The rich information content of MEG facilitates many disparate measures of connectivity between spatially separate regions and in this paper we discuss a single metric known as power envelope correlation. We review in detail the methodology required to measure power envelope correlation including (i) projection of MEG data into source space, (ii) removing confounds introduced by the MEG inverse problem and (iii) estimation of connectivity itself. In this way, we aim to provide researchers with a description of the key steps required to assess envelope based functional networks, which are thought to represent an intrinsic mode of coupling in the human brain. We highlight the principal findings of the techniques discussed, and furthermore, we show evidence that this method can probe how the brain forms and dissolves multiple transient networks on a rapid timescale in order to support current processing demand. Overall, power envelope correlation offers a unique and verifiable means to gain novel insights into network coordination and is proving to be of significant value in elucidating the neural dynamics of the human connectome in health and disease.
Directory of Open Access Journals (Sweden)
Chih-Wei Tsao
2016-01-01
Full Text Available Background: This study investigated the correlation between epicardial adipose tissue (EAT, a measure of central obesity, and sexual function in males with vasculogenic erectile dysfunction (ED. Materials and Methods: The study was a cross-sectional study of selected males with ED aged <75 years who attended the Urology Outpatient Department of Tri-Service General Hospital. Sixty subjects were included in the study, which employed biochemical data, anthropometric indexes, echocardiography, and questionnaires. Biochemical lipid profiles and associated inflammation markers were recorded. The anthropometric indexes included general and central obesity and bioelectrical impedance analysis. Echocardiography results were assessed by a single experienced cardiologist and included epicardial and pericardial fat thickness measurements. Sexual function was evaluated using the International Index of Erectile Function-5 (IIEF-5 score. Results: According to the analysis of variance and multivariate logistic regression, only the erectile hardness score (EHS was statistically positively correlated with the IIEF-5 score. All other anthropometric indexes and echocardiography parameters, including EAT thickness, pericardial adipose tissue thickness, and ejection fraction (EF, were not significantly associated with sexual function. Conclusions: Only EHS was statistically associated with sexual function in the male subjects with ED. The anthropometric indexes and EAT thickness, a measure of central obesity, were not significantly correlated with sexual function in the male patients with ED.
Intercomparison of a correlated-photon-based method to measure detector quantum efficiency.
Migdall, Alan; Castelletto, Stefania; Degiovanni, Ivo Pietro; Rastello, Maria Luisa
2002-05-20
We report on the absolute calibration of photodetector quantum efficiency by using correlated photon sources, performed independently at two laboratories, the National Institute of Standards and Technology and the Istituto Elettrotecnico Nazionale (IEN). The goal is to use an interlaboratory comparison to demonstrate the inherent absoluteness of the photon correlation technique by showing its independence from the particular experimental setup. We find that detector nonuniformity limited this comparison rather than uncertainty inherent in the method itself. The ultimate goal of these investigations is development of a robust measurement protocol that allows the uncertainties of individual measurements to be determined experimentally and verified operationally. Furthermore, to demonstrate the generality of the procedure, the IEN measurement setup was also used to calibrate a fiber-coupled avalanche photodiode module. Uncertainties are evaluated for the detector both with and without fiber coupling and differences are discussed. The current IEN setup using a thinner and higher transmittance nonlinear crystal for the generation of correlated photons shows a significant improvement in overall accuracy with respect to previously reported results from IEN [Metrologia 32, 501-503 (1996)].
Measurements of n-p correlations in the reaction of relativistic neon with uranium
Frankel, K.; Schimmerling, W.; Rasmussen, J. O.; Crowe, K. M.; Bistirlich, J.; Bowman, H.; Hashimoto, O.; Murphy, D. L.; Ridout, J.; Sullivan, J. P.; Yoo, E.; McDonald, W. J.; Salomon, M.; Xu, J. S.
1986-01-01
We report a preliminary measurement of coincident neutron-proton pairs emitted at 45 degrees in the interaction of 400, 530, and 650 MeV/A neon beams incident on uranium. Charged particles were identified by time of flight and momentum, as determined in a magnetic spectrometer. Neutral particles were detected using a thick plastic scintillator, and their time of flight was measured between an entrance scintillator, triggered by a charged particle, and the neutron detector. The scatter plots and contour plots of neutron momentum vs. proton momentum appear to show a slight correlation ridge above an uncorrelated background. The projections of this plane on the n-p momentum difference axis are essentially flat, showing a one standard deviation enhancement for each of the three beams energies. At each beam energy, the calculated momentum correlation function for the neutron-proton pairs is enhanced near zero neutron-proton momentum difference by approximately one standard deviation over the expected value for no correlation. This enhancement is expected to occur as a consequence of the attractive final state interaction between the neutron and proton (i.e., virtual or "singlet" deuterons). The implications of these measurements are discussed.
Measuring Gaussian Quantum Information and Correlations Using the Rényi Entropy of Order 2
Adesso, Gerardo; Girolami, Davide; Serafini, Alessio
2012-11-01
We demonstrate that the Rényi-2 entropy provides a natural measure of information for any multimode Gaussian state of quantum harmonic systems, operationally linked to the phase-space Shannon sampling entropy of the Wigner distribution of the state. We prove that, in the Gaussian scenario, such an entropy satisfies the strong subadditivity inequality, a key requirement for quantum information theory. This allows us to define and analyze measures of Gaussian entanglement and more general quantum correlations based on such an entropy, which are shown to satisfy relevant properties such as monogamy.
Measurement of 2- and 3-Nucleon Short Range Correlation Probabilities in Nuclei
Egiyan, K S; Sargsian, M M; Strikman, M I; Weinstein, L B; Adams, G; Ambrozewicz, P; Anghinolfi, M; Asavapibhop, B; Asryan, G; Avakian, H; Baghdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Batourine, V; Battaglieri, M; Bedlinskiy, I; Bektasoglu, M; Bellis, M; Benmouna, N; Biselli, A S; Bonner, B E; Bouchigny, S; Boiarinov, S; Bradford, R; Branford, D; Brooks, W K; Bültmann, S; Burkert, V D; Bultuceanu, C; Calarco, J R; Careccia, S L; Carman, D S; Carnahan, B; Chen, S; Cole, P L; Coltharp, P; Corvisiero, P; Crabb, D; Crannell, H; Cummings, J P; De Sanctis, E; De Vita, R; Degtyarenko, P V; Denizli, H; Dennis, L; Dharmawardane, K V; Djalali, C; Dodge, G E; Donnelly, J; Doughty, D; Dragovitsch, P; Dugger, M; Dytman, S; Dzyubak, O P; Egiyan, H; Elouadrhiri, L; Empl, A; Eugenio, P; Fatemi, R; Fedotov, G; Feuerbach, R J; Forest, T A; Funsten, H; Gavalian, G; Gevorgyan, N G; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Golovatch, E; Gothe, R W; Griffioen, K A; Guidal, M; Guillo, M; Guler, N; Guo, L; Gyurjyan, V; Hadjidakis, C; Hardie, J; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Hu, J; Huertas, M; Hyde-Wright, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Ito, M M; Jenkins, D; Jo, H S; Joo, K; Jüngst, H G; Kellie, J D; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Klimenko, A; Klusman, M; Kramer, L H; Kubarovski, V; Kühn, J; Kuhn, S E; Kuleshov, S; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Lee, T; Livingston, K; Maximon, L C; McAleer, S; McKinnon, B; McNabb, J W C; Mecking, B A; Mestayer, M D; Meyer, C A; Mibe, T; Mikhailov, K; Minehart, R C; Mirazita, M; Miskimen, R; Mokeev, V; Morrow, S A; Müller, J; Mutchler, G S; Nadel-Turonski, P; Napolitano, J; Nasseripour, R; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niyazov, R A; O'Rielly, G V; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Peterson, C; Pierce, J; Pivnyuk, N; Pocanic, D; Pogorelko, O I; Polli, E; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Qin, L M; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Ronchetti, F; Rosner, G; Rossi, P; Rowntree, D; Rubin, P D; Sabatie, F; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Sharabyan, Yu G; Shaw, J; Smith, E S; Smith, L C; Sober, D I; Stavinsky, A V; Stepanyan, S; Stokes, B E; Stoler, P; Strauch, S; Suleiman, R; Taiuti, M; Taylor, S; Tedeschi, D J; Thompson, R; Tkabladze, A; Tkachenko, S I; Todor, L; Tur, C; Ungaro, M; Vineyard, M F; Vlassov, A V; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zana, L; Zhang, J
2006-01-01
The ratios of inclusive electron scattering cross sections of He4, C12 and Fe56 to He3 have been measured at 1 1.4 GeV^2, the ratios exhibit two separate plateaus, at 1.5 2.25. This pattern is predicted by models that include 2- and 3-nucleon short-range correlations (SRC). Relative to A=3, the per-nucleon probabilities of 3-nucleon SRC are 2.3, 3.2, and 4.6 times larger for A=4, 12 and 56. This is the first measurement of 3-nucleon SRC probabilities in nuclei. \\\\
Measurement of Charm and Beauty Photoproduction at HERA using D* mu Correlations
Aktas, A; Anthonis, T; Asmone, A; Babaev, A; Backovic, S; Bähr, J; Baranov, P; Barrelet, E; Bartel, Wulfrin; Baumgartner, S; Becker, J; Beckingham, M; Behnke, O; Behrendt, O; Belousov, A; Berger, C; Berger, N; Berndt, T; Bizot, J C; Böhme, J; Boenig, M O; Boudry, V; Bracinik, J; Brisson, V; Broker, H B; Brown, D P; Bruncko, Dusan; Büsser, F W; Bunyatyan, A; Buschhorn, G; Bystritskaya, L; Campbell, A J; Caron, S; Cassol-Brunner, F; Cerny, K; Chekelian, V; Contreras, J G; Coppens, Y R; Coughlan, J A; Cox, B E; Cozzika, G; Cvach, J; Dainton, J B; Dau, W D; Daum, K; Delcourt, B; Demirchyan, R; de Roeck, A; Desch, Klaus; De Wolf, E A; Diaconu, C; Dingfelder, J; Dodonov, V; Dubak, A; Duprel, C; Eckerlin, G; Efremenko, V; Egli, S; Eichler, R; Eisele, F; Ellerbrock, M; Elsen, E; Erdmann, W; Faulkner, P J W; Favart, L; Fedotov, A; Felst, R; Ferencei, J; Fleischer, M; Fleischmann, P; Fleming, Y H; Flucke, G; Flügge, G; Fomenko, A; Foresti, I; Formánek, J; Franke, G; Frising, G; Gabathuler, Erwin; Gabathuler, K; Garutti, E; Garvey, J; Gayler, J; Gerhards, R; Gerlich, C; Ghazaryan, S; Ginzburgskaya, S; Görlich, L; Gogitidze, N; Gorbounov, S; Grab, C; Grässler, Herbert; Greenshaw, T; Gregori, M; Grindhammer, G; Gwilliam, C; Haidt, D; Hajduk, L; Haller, J; Hansson, M; Heinzelmann, G; Henderson, R C W; Henschel, H; Henshaw, O; Herrera-Corral, G; Herynek, I; Heuer, R D; Hildebrandt, M; Hiller, K H; Hoting, P; Hoffmann, D; Horisberger, R P; Hovhannisyan, A; Ibbotson, M; Ismail, M; Jacquet, M; Janauschek, L; Janssen, X; Jemanov, V; Jönsson, L B; Johnson, D P; Jung, H; Kant, D; Kapichine, M; Karlsson, M; Katzy, J; Keller, N; Kenyon, I R; Kiesling, C; Klein, M; Kleinwort, C; Klimkovich, T; Kluge, T; Knies, G; Knutsson, A; Koblitz, B; Korbel, V; Kostka, P; Koutouev, R; Kropivnitskaya, A; Kroseberg, J; Krüger, K; Kuckens, J; Landon, M P J; Lange, W; Lastoviicka, T; Laycock, P; Lebedev, A; Leiner, B; Lemrani, R; Lendermann, V; Levonian, S; Lindfeld, L; Lipka, K; List, B; Lobodzinska, E; Loktionova, N; López-Fernandez, R; Lubimov, V; Lüders, H; Lüke, D; Lux, T; Lytkin, L; Makankine, A; Malden, N; Malinovskii, E I; Mangano, S; Marage, P; Marks, J; Marshall, R; Martisikova, M; Martyn, H U; Maxfield, S J; Meer, D; Mehta, A; Meier, K; Meyer, A B; Meyer, H; Meyer, J; Mikocki, S; Milcewicz-Mika, I; Milstead, D; Mohamed, A; Moreau, F; Morozov, A; Morris, J V; Mozer, M U; Müller, K; Murn, P; Nagovizin, V; Nankov, K; Naroska, Beate; Naumann, J; Naumann, T; Newman, P R; Niebuhr, C B; Nikiforov, A; Nikitin, D K; Nowak, G; Nozicka, M; Oganezov, R; Olivier, B; Olsson, J E; Ozerov, D; Paramonov, A A; Pascaud, C; Patel, G D; Peez, M; Pérez, E; Perieanu, A; Petrukhin, A; Pitzl, D; Placakyte, R; Pöschl, R; Portheault, B; Povh, B; Raicevic, N; Reimer, P; Reisert, B; Rimmer, A; Risler, C; Rizvi, E; Robmann, P; Roland, B; Roosen, R; Rostovtsev, A; Rurikova, Z; Rusakov, S V; Rybicki, K; Sankey, D P C; Sauvan, E; Schatzel, S; Scheins, J; Schilling, F P; Schleper, P; Schmidt, S; Schmitt, S; Schneider, M; Schoeffel, L; Schöning, A; Schröder, V; Schultz-Coulon, H C; Schwanenberger, C; Sedlak, K; Sefkow, F; Shevyakov, I; Shtarkov, L N; Sirois, Y; Sloan, T; Smirnov, P; Soloviev, Yu; South, D; Spaskov, V; Specka, A; Spitzer, H; Stamen, R; Stella, B; Stiewe, J; Strauch, I; Straumann, U; Tchoulakov, V; Thompson, G; Thompson, P D; Tomasz, F; Traynor, D; Truöl, P; Tsipolitis, G; Tsurin, I; Turnau, J; Tzamariudaki, E; Uraev, A; Urban, M; Usik, A; Utkin, D; Valkár, S; Valkárová, A; Vallée, C; Van Mechelen, P; Van Remortel, N; Vargas-Trevino, A; Vazdik, Ya A; Veelken, C; Vest, A; Vinokurova, S; Volchinski, V; Wacker, K; Wagner, J; Weber, G; Weber, R; Wegener, D; Werner, C; Werner, N; Wessels, M; Wessling, B; Winter, G G; Wissing, C; Woerling, E E; Wolf, R; Wünsch, E; Xella, S M; Yan, W; Yeganov, V; Zaicek, J; Zaleisak, J; Zhang, Z; Zhelezov, A; Zhokin, A; Zohrabyan, H G; Zomer, F
2005-01-01
A measurement of charm and beauty photoproduction at the electron proton collider HERA is presented based on the simultaneous detection of a D*^{\\pm} meson and a muon. The correlation between the D* meson and the muon serves to separate the charm and beauty contributions and the analysis provides comparable sensitivity to both. The total and differential experimental cross sections are compared to LO and NLO QCD calculations. The measured charm cross section is in good agreement with QCD predictions including higher order effects while the beauty cross section is higher.
Femtosecond x-ray free electron laser pulse duration measurement from spectral correlation function
Directory of Open Access Journals (Sweden)
A. A. Lutman
2012-03-01
Full Text Available We present a novel method for measuring the duration of femtosecond x-ray pulses from self-amplified spontaneous emission free electron lasers by performing statistical analysis in the spectral domain. Analytical expressions of the spectral correlation function were derived in the linear regime to extract both the pulse duration and the spectrometer resolution. Numerical simulations confirmed that the method can be also used in the nonlinear regime. The method was demonstrated experimentally at the Linac Coherent Light Source by measuring pulse durations down to 13 fs FWHM.
Measurement of noise and its correlation to performance and geometry of small aircraft propellers
Štorch, Vít; Nožička, Jiří; Brada, Martin; Gemperle, Jiří; Suchý, Jakub
2016-03-01
A set of small model and UAV propellers is measured both in terms of aerodynamic performance and acoustic noise under static conditions. Apart from obvious correlation of noise to tip speed and propeller diameter the influence of blade pitch, blade pitch distribution, efficiency and shape of the blade is sought. Using the measured performance data a computational model for calculation of aerodynamic noise of propellers will be validated. The range of selected propellers include both propellers designed for nearly static conditions and propellers that are running at highly offdesign conditions, which allows to investigate i.e. the effect of blade stall on both noise level and performance results.
Measurement of noise and its correlation to performance and geometry of small aircraft propellers
Directory of Open Access Journals (Sweden)
Štorch Vít
2016-01-01
Full Text Available A set of small model and UAV propellers is measured both in terms of aerodynamic performance and acoustic noise under static conditions. Apart from obvious correlation of noise to tip speed and propeller diameter the influence of blade pitch, blade pitch distribution, efficiency and shape of the blade is sought. Using the measured performance data a computational model for calculation of aerodynamic noise of propellers will be validated. The range of selected propellers include both propellers designed for nearly static conditions and propellers that are running at highly offdesign conditions, which allows to investigate i.e. the effect of blade stall on both noise level and performance results.
Measurement of Local Deformations in Steel Monostrands Using Digital Image Correlation
DEFF Research Database (Denmark)
Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.
2014-01-01
, difficulties with the placement of strain gauges in the vicinity of the anchorage, and, most importantly, the relatively small magnitude of deformation occurring in the monostrand. This paper focuses on the measurement of localized deformations in high-strength steel monostrands using the digital image...... correlation (DIC) technique. The presented technique enables the measurement of individual wire strains along the length of the monostrand and also provides quantitative information on the relative movement between individual wires, leading to a more in-depth understanding of the underlying fatigue mechanisms...
An assessment of the precision and confidence of aquatic eddy correlation measurements
DEFF Research Database (Denmark)
Donis, Daphne; Holtappels, Moritz; Noss, Christian
2015-01-01
, an accurate assessment of the errors introduced by the spatial alignment of velocity and water constituent measurements and by their different response times is still needed. Here, this paper discusses uncertainties and biases in the data treatment based on oxygen EC flux measurements in a large-scale flume...... series based on maximum cross correlation improved the precision of EC flux estimations; 2) an oxygen sensor with a response time of ...) between the oxygen sensor and the ADV's sampling volume is important for accurate EC flux estimates, especially when the flow direction is perpendicular to the sensor's orientation....
Measuring two-particle Bose-Einstein correlations with PHOBOS@RHIC
Energy Technology Data Exchange (ETDEWEB)
Betts, R.; Barton, D.; Carroll, A. [and others
1995-07-15
The authors present results of a simulation of the measurement of two-particle Bose-Einstein correlations in central Au-Au collisions with the PHOBOS detector at RHIC. This measurement is expected to yield information on the relevant time and distance scales in these collisions. As the space-time scale is directly connected with the equation of state governing the evolution of the particle source, this information will be essential in understanding the physics of nucleus-nucleus collisions at RHIC energies. The authors demonstrate that the PHOBOS detector has sufficient resolution and acceptance to distinguish a variety of physics scenarios.
Measuring epistasis in fitness landscapes: The correlation of fitness effects of mutations.
Ferretti, Luca; Schmiegelt, Benjamin; Weinreich, Daniel; Yamauchi, Atsushi; Kobayashi, Yutaka; Tajima, Fumio; Achaz, Guillaume
2016-05-01
Genotypic fitness landscapes are constructed by assessing the fitness of all possible combinations of a given number of mutations. In the last years, several experimental fitness landscapes have been completely resolved. As fitness landscapes are high-dimensional, simple measures of their structure are used as statistics in empirical applications. Epistasis is one of the most relevant features of fitness landscapes. Here we propose a new natural measure of the amount of epistasis based on the correlation of fitness effects of mutations. This measure has a natural interpretation, captures well the interaction between mutations and can be obtained analytically for most landscape models. We discuss how this measure is related to previous measures of epistasis (number of peaks, roughness/slope, fraction of sign epistasis, Fourier-Walsh spectrum) and how it can be easily extended to landscapes with missing data or with fitness ranks only. Furthermore, the dependence of the correlation of fitness effects on mutational distance contains interesting information about the patterns of epistasis. This dependence can be used to uncover the amount and nature of epistatic interactions in a landscape or to discriminate between different landscape models.
Directory of Open Access Journals (Sweden)
Khoo Sze-Wei
2016-09-01
Full Text Available Among the full-field optical measurement methods, the Digital Image Correlation (DIC is one of the techniques which has been given particular attention. Technically, the DIC technique refers to a non-contact strain measurement method that mathematically compares the grey intensity changes of the images captured at two different states: before and after deformation. The measurement can be performed by numerically calculating the displacement of speckles which are deposited on the top of object’s surface. In this paper, the Two-Dimensional Digital Image Correlation (2D-DIC is presented and its fundamental concepts are discussed. Next, the development of the 2D-DIC algorithms in the past 33 years is reviewed systematically. The improvement of 2DDIC algorithms is presented with respect to two distinct aspects: their computation efficiency and measurement accuracy. Furthermore, analysis of the 2D-DIC accuracy is included, followed by a review of the DIC applications for two-dimensional measurements.
Hall, Alex
2016-01-01
We investigate the feasibility of measuring the effects of peculiar velocities in large-scale structure using the dipole of the redshift-space cross-correlation function. We combine number counts of galaxies with brightness-temperature fluctuations from 21cm intensity mapping, demonstrating that the dipole may be measured at modest significance ($\\lesssim 2\\sigma$) by combining the upcoming radio survey CHIME with the future redshift surveys of DESI and Euclid. More significant measurements ($\\lesssim~10\\sigma$) will be possible by combining intensity maps from the SKA with these of DESI or Euclid, and an even higher significance measurement ($\\lesssim 100\\sigma$) may be made by combining observables completely internally to the SKA. We account for effects such as contamination by wide-angle terms, interferometer noise and beams in the intensity maps, non-linear enhancements to the power spectrum, stacking multiple populations, sensitivity to the magnification slope, and the possibility that number counts and...
Directory of Open Access Journals (Sweden)
RODRIGO GOYANNES GUSMÃO CAIADO
2016-12-01
Full Text Available Over the past few years, issues of sustainability are gaining greater prominence among organizations and their stakeholders around the world and with it the effective measurement of environmental performance has been a challenge for sustainable transition. The purpose of the article is to analyse, through the the perception of market experts and researchers, what sustainable performance measures have stronger positive correlation to achieve organizational sustainability in order to help employees in making decisions that reduce the consumption of resources and that create value throughout its chain. The research is of an exploratory and descriptive nature, with qualitative and quantitative method and has a deductive logic. It aims to help professionals and academics who want to start the measurement and continuous improvement of economic, environmental, social, governance and technical performance of their organizations. Finally, the analyzes allow direct efforts to sustainable measures considered most important, allowing the transition of the organization for sustainability.
Measurement of correlated b bmacr production in p pmacr collisions at s=1960GeV
Aaltonen, T.; Abulencia, A.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M. G.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; Annovi, A.; Antos, J.; Aoki, M.; Apollinari, G.; Arisawa, T.; Artikov, A.; Ashmanskas, W.; Attal, A.; Aurisano, A.; Azfar, F.; Azzi-Bacchetta, P.; Azzurri, P.; Bacchetta, N.; Badgett, W.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Baroiant, S.; Bartsch, V.; Bauer, G.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Belloni, A.; Benjamin, D.; Beretvas, A.; Beringer, J.; Berry, T.; Bhatti, A.; Binkley, M.; Bisello, D.; Bizjak, I.; Blair, R. E.; Blocker, C.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Boisvert, V.; Bolla, G.; Bolshov, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brau, B.; Brigliadori, L.; Bromberg, C.; Brubaker, E.; Budagov, J.; Budd, H. S.; Budd, S.; Burkett, K.; Busetto, G.; Bussey, P.; Byrum, K. L.; Cabrera, S.; Campanelli, M.; Campbell, M.; Canelli, F.; Canepa, A.; Carrillo, S.; Carlsmith, D.; Carosi, R.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chang, S. H.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, I.; Cho, K.; Chokheli, D.; Chou, J. P.; Choudalakis, G.; Chuang, S. H.; Chung, K.; Chung, W. H.; Chung, Y. S.; Cilijak, M.; Ciobanu, C. I.; Ciocci, M. A.; Clark, A.; Clark, D.; Coca, M.; Compostella, G.; Convery, M. E.; Conway, J.; Cooper, B.; Copic, K.; Cordelli, M.; Cortiana, G.; Crescioli, F.; Cuenca Almenar, C.; Cuevas, J.; Culbertson, R.; Cully, J. C.; Daronco, S.; Datta, M.; D'Auria, S.; Davies, T.; Dagenhart, D.; de Barbaro, P.; de Cecco, S.; Deisher, A.; de Lentdecker, G.; de Lorenzo, G.; Dell'Orso, M.; Delli Paoli, F.; Demortier, L.; Deng, J.; Deninno, M.; de Pedis, D.; Derwent, P. F.; di Giovanni, G. P.; Dionisi, C.; di Ruzza, B.; Dittmann, J. R.; D'Onofrio, M.; Dörr, C.; Donati, S.; Dong, P.; Donini, J.; Dorigo, T.; Dube, S.; Efron, J.; Erbacher, R.; Errede, D.; Errede, S.; Eusebi, R.; Fang, H. C.; Farrington, S.; Fedorko, I.; Fedorko, W. T.; Feild, R. G.; Feindt, M.; Fernandez, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Forrester, S.; Franklin, M.; Freeman, J. C.; Furic, I.; Gallinaro, M.; Galyardt, J.; Garcia, J. E.; Garberson, F.; Garfinkel, A. F.; Gay, C.; Gerberich, H.; Gerdes, D.; Giagu, S.; Giannetti, P.; Gibson, K.; Gimmell, J. L.; Ginsburg, C.; Giokaris, N.; Giordani, M.; Giromini, P.; Giunta, M.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldschmidt, N.; Goldstein, J.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gresele, A.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Grundler, U.; Guimaraes da Costa, J.; Gunay-Unalan, Z.; Haber, C.; Hahn, K.; Hahn, S. R.; Halkiadakis, E.; Hamilton, A.; Han, B.-Y.; Han, J. Y.; Handler, R.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harper, S.; Harr, R. F.; Harris, R. M.; Hartz, M.; Hatakeyama, K.; Hauser, J.; Hays, C.; Heck, M.; Heijboer, A.; Heinemann, B.; Heinrich, J.; Henderson, C.; Herndon, M.; Heuser, J.; Hidas, D.; Hill, C. S.; Hirschbuehl, D.; Hocker, A.; Holloway, A.; Hou, S.; Houlden, M.; Hsu, S.-C.; Huffman, B. T.; Hughes, R. E.; Husemann, U.; Huston, J.; Incandela, J.; Introzzi, G.; Iori, M.; Ivanov, A.; Iyutin, B.; James, E.; Jang, D.; Jayatilaka, B.; Jeans, D.; Jeon, E. J.; Jindariani, S.; Johnson, W.; Jones, M.; Joo, K. K.; Jun, S. Y.; Jung, J. E.; Junk, T. R.; Kamon, T.; Karchin, P. E.; Kato, Y.; Kemp, Y.; Kephart, R.; Kerzel, U.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kimura, N.; Kirsch, L.; Klimenko, S.; Klute, M.; Knuteson, B.; Ko, B. R.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Korytov, A.; Kotwal, A. V.; Kraan, A. C.; Kraus, J.; Kreps, M.; Kroll, J.; Krumnack, N.; Kruse, M.; Krutelyov, V.; Kubo, T.; Kuhlmann, S. E.; Kuhr, T.; Kulkarni, N. P.; Kusakabe, Y.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; Lazzizzera, I.; Lecompte, T.; Lee, J.; Lee, J.; Lee, Y. J.; Lee, S. W.; Lefèvre, R.; Leonardo, N.; Leone, S.; Levy, S.; Lewis, J. D.; Lin, C.; Lin, C. S.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, T.; Lockyer, N. S.; Loginov, A.; Loreti, M.; Lu, R.-S.; Lucchesi, D.; Lujan, P.; Lukens, P.; Lungu, G.; Lyons, L.; Lys, J.; Lysak, R.; Lytken, E.; Mack, P.; Madrak, R.; Maeshima, K.; Makhoul, K.; Maki, T.; Maksimovic, P.; Malde, S.; Malik, S.; Manca, G.; Manousakis, A.; Margaroli, F.; Marginean, R.; Marino, C.; Marino, C. P.; Martin, A.; Martin, M.; Martin, V.; Martínez, M.; Martínez-Ballarín, R.; Maruyama, T.; Mastrandrea, P.; Masubuchi, T.; Matsunaga, H.; Mattson, M. E.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Menzemer, S.; Menzione, A.; Merkel, P.; Mesropian, C.; Messina, A.; Miao, T.; Miladinovic, N.; Miles, J.; Miller, R.; Mills, C.; Milnik, M.; Mitra, A.; Mitselmakher, G.; Miyamoto, A.; Moed, S.; Moggi, N.; Mohr, B.; Moon, C. S.; Moore, R.; Morello, M.; Movilla Fernandez, P.; Mülmenstädt, J.; Mukherjee, A.; Muller, Th.; Mumford, R.; Murat, P.; Mussini, M.; Nachtman, J.; Nagano, A.; Naganoma, J.; Nakamura, K.; Nakano, I.; Napier, A.; Necula, V.; Neu, C.; Neubauer, M. S.; Nielsen, J.; Nodulman, L.; Norniella, O.; Nurse, E.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Oldeman, R.; Orava, R.; Osterberg, K.; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Papaikonomou, A.; Paramonov, A. A.; Parks, B.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Piedra, J.; Pinera, L.; Pitts, K.; Plager, C.; Pondrom, L.; Portell, X.; Poukhov, O.; Pounder, N.; Prakoshyn, F.; Pronko, A.; Proudfoot, J.; Ptohos, F.; Punzi, G.; Pursley, J.; Rademacker, J.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Reisert, B.; Rekovic, V.; Renton, P.; Rescigno, M.; Richter, S.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rogers, E.; Rolli, S.; Roser, R.; Rossi, M.; Rossin, R.; Ruiz, A.; Russ, J.; Rusu, V.; Saarikko, H.; Safonov, A.; Sakumoto, W. K.; Salamanna, G.; Saltó, O.; Santi, L.; Sarkar, S.; Sartori, L.; Sato, K.; Savoy-Navarro, A.; Scheidle, T.; Schlabach, P.; Schmidt, E. E.; Schmidt, M. P.; Schmitt, M.; Schwarz, T.; Scodellaro, L.; Scott, A. L.; Scribano, A.; Scuri, F.; Sedov, A.; Seidel, S.; Seiya, Y.; Semenov, A.; Sexton-Kennedy, L.; Sfyrla, A.; Shalhout, S. Z.; Shapiro, M. D.; Shears, T.; Shepard, P. F.; Sherman, D.; Shimojima, M.; Shochet, M.; Shon, Y.; Shreyber, I.; Sidoti, A.; Sisakyan, A.; Slaughter, A. J.; Slaunwhite, J.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Soderberg, M.; Soha, A.; Somalwar, S.; Sorin, V.; Spalding, J.; Spinella, F.; Squillacioti, P.; Stanitzki, M.; Staveris-Polykalas, A.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.; Strologas, J.; Stuart, D.; Suh, J. S.; Sukhanov, A.; Sun, H.; Suslov, I.; Suzuki, T.; Taffard, A.; Takashima, R.; Takeuchi, Y.; Tanaka, R.; Tecchio, M.; Teng, P. K.; Terashi, K.; Thom, J.; Thompson, A. S.; Thomson, E.; Tipton, P.; Tiwari, V.; Tkaczyk, S.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Tourneur, S.; Tsuno, S.; Tu, Y.; Turini, N.; Ukegawa, F.; Uozumi, S.; Vallecorsa, S.; van Remortel, N.; Varganov, A.; Vataga, E.; Vazquez, F.; Velev, G.; Vellidis, C.; Veramendi, G.; Veszpremi, V.; Vidal, M.; Vidal, R.; Vila, I.; Vilar, R.; Vine, T.; Vogel, M.; Volobouev, I.; Volpi, G.; Würthwein, F.; Wagner, P.; Wagner, R. G.; Wagner, R. L.; Wagner, J.; Wagner, W.; Wallny, R.; Wang, S. M.; Waters, D.; Weinberger, M.; Wester, W. C., III; Whitehouse, B.; Whiteson, D.; Wicklund, E.; Williams, H. H.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, C.; Wright, T.; Wu, X.; Wynne, S. M.; Yagil, A.; Yamamoto, K.; Yamaoka, J.; Yamashita, T.; Yang, C.; Yang, U. K.; Yang, Y. C.; Yao, W. M.; Yeh, G. P.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanello, L.; Zanetti, A.; Zaw, I.; Zhang, X.; Zhou, J.; Zucchelli, S.
2008-04-01
We present a measurement of the correlated b bmacr production cross section. The data used in this analysis were taken with the upgraded CDF detector (CDF II) at the Fermilab Tevatron collider, and correspond to an integrated luminosity of 742pb-1. We utilize muon pairs with invariant mass 5≤mμμ≤80GeV/c2 produced by b bmacr double semileptonic decays. For muons with pT≥3GeV/c and |η|≤0.7, that are produced by b and bmacr quarks with pT≥2GeV/c and |y|≤1.3, we measure σb→μ, bmacr →μ=1549±133pb. We compare this result with theoretical predictions and previous measurements. We also report the measurement of σc→μ, cmacr →μ, a by-product of the study of the background to b bmacr production.
Csörgö, T; Kittel, W; Novak, T
2010-01-01
L3 preliminary data of two-particle Bose-Einstein correlations are reported for hadronic Z^0 decays in e+e- annihilation at LEP. The invariant relative momentum Q is identified as the eigenvariable of the measured correlation function. Significant anti-correlations are observed in the Bose-Einstein correlation function in a broad region of 0.5 - 1.6 GeV with a minimum at Q close to 0.8 GeV. Absence of Bose-Einstein correlations is demonstrated in the region above Q >= 1.6 GeV. The effective source size is found to decrease with increasing value of the transverse mass of the pair, similarly to hadron-hadron and heavy ion reactions. These feautes and our data are described well by the non-thermal tau-model, which is based on strong space-time momentum-correlations.
Use of a Digital Image Correlation Technique for Measuring the Material Properties of Beetle Wing
Institute of Scientific and Technical Information of China (English)
Tailie Jin; Nam Seo Goo; Sung-Choong Woo; Hoon Cheol Park
2009-01-01
Beetle wings are very specialized flight organs consisting of the veins and membranes. Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally. In the present study, we have used a Digital lmage Correlation (DIC) technique to measure the elastic modulus of a beetle wing membrane. Specimens were prepared by carefully cutting a beetle hind wing into 3.0 mm by 7.0 mm segments (the gage length was 5 mm). We used a scanning electron microscope for a precise measurement of the thickness of the beetle wing membrane. The specimen was attached to a designed fixture to induce a uniform displacement by means of a micromanipulator. We used an ARAMISTM system based on the digital image correlation technique to measure the corresponding displacement of a specimen. The thickness of the beetle wing varied at different points of the membrane. The elastic modulus differed in relation to the membrane arrangement showing a structural anisotropy; the elastic modulus in the chordwise direction is approximately 2.65 GPa, which is three times larger than the elastic modulus in the spanwise direction of 0.84 GPa. As a result, the digital image correlation-based ARAMIS system was suc-cessfully used to measure the elastic modulus of a beetle wing. In addition to membrane's elastic modulus, we considered the Poisson's ratio of the membrane and measured the elastic modulus of a vein using an Instron universal tensile machine. The result reveals the Poisson's ratio is nearly zero and the elastic modulus of a vein is about 11 GPa.
Filipović Grčić, Petar; Matijaca, Meri; Bilić, Ivica; Džamonja, Gordan; Lušić, Ivo; Čaljkušić, Krešimir; Čapkun, Vesna
2013-12-01
Walking limitation assessment in multiple sclerosis patients (MSPs) is a demanding task, especially in the clinical setting. The aim of this study is to correlate the visual analogue scale (VAS), a simple method for measuring subjective experience, with measures of walking ability used in clinical research of MS. The study included 82 ambulatory MSPs who have resided in the local community. The applied measures of walking ability were the following: the single-item and patient-rated Walking Ability Visual Analogue Scale (WA-VAS), the Expanded Disability Status Scale (EDSS), the 25-foot walk test (25FWT), the Six Spot Step Test (SSST), the 2 min timed walk (2 min TW), the Multiple Sclerosis Walking Scale-12 (MSWS-12), and step activity monitor accelerometer (SAM) during 7 day period. The SAM analysis included the average daily step count, the average steps/min of the highest 1 min of a day, and the average steps/min of the highest continuous 60 min of a day. The WA-VAS scores significantly and strongly correlated with EDSS (ρ = 0.679, P < 0.001), 25FWT (ρ = 0.606, P < 0.001), SSST (ρ = 0.729, P < 0.001), 2 min TW (ρ = -0.643, P < 0.001), MSWS-12 (ρ = 0.746, P < 0.001), average daily step count (ρ = -0.507, P < 0.001), average steps/min of the highest 1 min of a day (ρ = -0.544, P < 0.001), and average steps/min of the highest continuous 60 min of a day (ρ = -0.473, P < 0.001). Correlations between WA-VAS and measures of walking ability used in clinical research of MS were satisfactory. The results obtained in this research indicate that the WA-VAS could be an instrument for simple measurement of walking limitations in MSPs in the clinical setting.
Shao, Xinxing; Dai, Xiangjun; Chen, Zhenning; Dai, Yuntong; Dong, Shuai; He, Xiaoyuan
2016-12-01
The development of stereo-digital image correlation (stereo-DIC) enables the application of vision-based technique that uses digital cameras to the deformation measurement of materials and structures. Compared with traditional contact measurements, the stereo-DIC technique allows for non-contact measurement, has a non-intrusive characteristic, and can obtain full-field deformation information. In this paper, a speckle-based calibration method is developed to calibrate the stereo-DIC system when the system is applied for deformation measurement of large engineering components. By combining speckle analysis with the classical relative orientation algorithm, relative rotation and translation between cameras can be calibrated based on analysis of experimental speckle images. For validation, the strain fields of a four-point bending beam and an axially loaded concrete column were determined by the proposed calibration method and stereovision measurement. As a practical application, the proposed calibration method was applied for strain measurement of a ductile iron cylindrical vessel in the drop test. The measured results verify that the proposed calibration method is effective for deformation measurement of large engineering components.
Brunker, J.; Beard, P.
2013-03-01
Blood flow measurements have been demonstrated using the acoustic resolution mode of photoacoustic sensing. This is unlike previous flowmetry methods using the optical resolution mode, which limits the maximum penetration depth to approximately 1mm. Here we describe a pulsed time correlation photoacoustic Doppler technique that is inherently flexible, lending itself to both resolution modes. Doppler time shifts are quantified via cross-correlation of pairs of photoacoustic waveforms generated in moving absorbers using pairs of laser light pulses, and the photoacoustic waves detected using an ultrasound transducer. The acoustic resolution mode is employed by using the transducer focal width, rather than the large illuminated volume, to define the lateral spatial resolution. The use of short laser pulses allows depth-resolved measurements to be obtained with high spatial resolution, offering the prospect of mapping flow within microcirculation. Whilst our previous work has been limited to a non-fluid phantom, we now demonstrate measurements in more realistic blood-mimicking phantoms incorporating fluid suspensions of microspheres flowing along an optically transparent tube. Velocities up to 110 mm/s were measured with accuracies approaching 1% of the known velocities, and resolutions of a few mm/s. The velocity range and resolution are scalable with excitation pulse separation, but the maximum measurable velocity was considerably smaller than the value expected from the detector focal beam width. Measurements were also made for blood flowing at velocities up to 13.5 mm/s. This was for a sample reduced to 5% of the normal haematocrit; increasing the red blood cell concentration limited the maximum measurable velocity so that no results were obtained for concentrations greater than 20% of a physiologically realistic haematocrit. There are several possible causes for this limitation; these include the detector bandwidth and irregularities in the flow pattern. Better
Measuring the height-to-height correlation function of corrugation in suspended graphene
Energy Technology Data Exchange (ETDEWEB)
Kirilenko, D.A., E-mail: Demid.Kirilenko@mail.ioffe.ru [Ioffe Institute, Politekhnicheskaya ul. 26, 194021 St-Petersburg (Russian Federation); EMAT, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); Brunkov, P.N. [Ioffe Institute, Politekhnicheskaya ul. 26, 194021 St-Petersburg (Russian Federation); ITMO University, Kronverksky pr. 49, 197101 St. Petersburg (Russian Federation)
2016-06-15
Nanocorrugation of 2D crystals is an important phenomenon since it affects their electronic and mechanical properties. The corrugation may have various sources; one of them is flexural phonons that, in particular, are responsible for the thermal conductivity of graphene. A study of corrugation of just the suspended graphene can reveal much of valuable information on the physics of this complicated phenomenon. At the same time, the suspended crystal nanorelief can hardly be measured directly because of high flexibility of the 2D crystal. Moreover, the relief portion related to rapid out-of-plane oscillations (flexural phonons) is also inaccessible by such measurements. Here we present a technique for measuring the Fourier components of the height–height correlation function H(q) of suspended graphene which includes the effect of flexural phonons. The technique is based on the analysis of electron diffraction patterns. The H(q) is measured in the range of wavevectors q≈0.4–4.5 nm{sup −1}. At the upper limit of this range H(q) does follow the T/κq{sup 4} law. So, we measured the value of suspended graphene bending rigidity κ=1.2±0.4 eV at ambient temperature T≈300 K. At intermediate wave vectors, H(q) follows a slightly weaker exponent than theoretically predicted q{sup −3.15} but is closer to the results of the molecular dynamics simulation. At low wave vectors, the dependence becomes even weaker, which may be a sign of influence of charge carriers on the dynamics of undulations longer than 10 nm. The technique presented can be used for studying physics of flexural phonons in other 2D materials. - Highlights: • A technique for measuring free-standing 2D crystal corrugation is proposed. • The height-to-height correlation function of the suspended graphene corrugation is measured. • Various parameters of the intrinsic graphene properties are experimentally determined.
Farzam, Parisa; Sutin, Jason; Wu, Kuan-Cheng; Zimmermann, Bernhard B.; Tamborini, Davide; Dubb, Jay; Boas, David A.; Franceschini, Maria Angela
2017-02-01
Intracranial pressure (ICP) monitoring has a key role in the management of neurosurgical and neurological injuries. Currently, the standard clinical monitoring of ICP requires an invasive transducer into the parenchymal tissue or the brain ventricle, with possibility of complications such as hemorrhage and infection. A non-invasive method for measuring ICP, would be highly preferable, as it would allow clinicians to promptly monitor ICP during transport and allow for monitoring in a larger number of patients. We have introduced diffuse correlation spectroscopy (DCS) as a non-invasive ICP monitor by fast measurement of pulsatile cerebral blood flow (CBF). The method is similar to Transcranial Doppler ultrasound (TCD), which derives ICP from the amplitude of the pulsatile cerebral blood flow velocity, with respect to the amplitude of the pulsatile arterial blood pressure. We believe DCS measurement is superior indicator of ICP than TCD estimation because DCS directly measures blood flow, not blood flow velocity, and the small cortical vessels measured by DCS are more susceptible to transmural pressure changes than the large vessels. For fast DCS measurements to recover pulsatile CBF we have developed a custom high-power long-coherent laser and a strategy for delivering it to the tissue within ANSI standards. We have also developed a custom FPGA-based correlator board, which facilitates DCS data acquisitions at 50-100 Hz. We have tested the feasibility of measuring pulsatile CBF and deriving ICP in two challenging scenarios: humans and rats. SNR is low in human adults due to large optode distances. It is similarly low in rats because the fast heart rate in this setting requires a high repetition rate.
MEASUREMENT OF 21 cm BRIGHTNESS FLUCTUATIONS AT z {approx} 0.8 IN CROSS-CORRELATION
Energy Technology Data Exchange (ETDEWEB)
Masui, K. W.; Switzer, E. R.; Calin, L.-M.; Pen, U.-L.; Shaw, J. R. [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George St., Toronto, Ontario, M5S 3H8 (Canada); Banavar, N. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, Ontario, M5S 3H4 (Canada); Bandura, K. [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec, H3A 2T8 (Canada); Blake, C. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122 (Australia); Chang, T.-C.; Liao, Y.-W. [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei, 10617, Taiwan (China); Chen, X.; Li, Y.-C. [National Astronomical Observatories, Chinese Academy of Science, 20A Datun Road, Beijing 100012 (China); Natarajan, A.; Peterson, J. B.; Voytek, T. C. [McWilliams Center for Cosmology, Carnegie Mellon University, Department of Physics, 5000 Forbes Ave., Pittsburgh, PA 15213 (United States)
2013-01-20
In this Letter, 21 cm intensity maps acquired at the Green Bank Telescope are cross-correlated with large-scale structure traced by galaxies in the WiggleZ Dark Energy Survey. The data span the redshift range 0.6 < z < 1 over two fields totaling {approx}41 deg. sq. and 190 hr of radio integration time. The cross-correlation constrains {Omega}{sub HI} b{sub HI} r = [0.43 {+-} 0.07(stat.) {+-} 0.04(sys.)] Multiplication-Sign 10{sup -3}, where {Omega}{sub HI} is the neutral hydrogen (H I) fraction, r is the galaxy-hydrogen correlation coefficient, and b{sub HI} is the H I bias parameter. This is the most precise constraint on neutral hydrogen density fluctuations in a challenging redshift range. Our measurement improves the previous 21 cm cross-correlation at z {approx} 0.8 both in its precision and in the range of scales probed.
Correlation of auditory brain stem response and the MRI measurements in neuro-degenerative disorders
Energy Technology Data Exchange (ETDEWEB)
Kamei, Hidekazu (Tokyo Women' s Medical Coll. (Japan))
1989-06-01
The purpose of this study is to elucidate correlations of several MRI measurements of the cranium and brain, functioning as a volume conductor, to the auditory brain stem response (ABR) in neuro-degenerative disorders. The subjects included forty-seven patients with spinocerebellar degeneration (SCD) and sixteen of amyotrophic lateral sclerosis (ALS). Statistically significant positive correlations were found between I-V and III-V interpeak latencies (IPLs) and the area of cranium and brain in the longitudinal section of SCD patients, and between I-III and III-V IPLs and the area in the longitudinal section of those with ALS. And, also there were statistically significant correlations between the amplitude of the V wave and the area of brain stem as well as that of the cranium in the longitudinal section of SCD patients, and between the amplitude of the V wave and the area of the cerebrum in the longitudinal section of ALS. In conclusion, in the ABR, the IPLs were prolonged and the amplitude of the V wave was decreased while the MRI size of the cranium and brain increased. When the ABR is applied to neuro-degenerative disorders, it might be important to consider not only the conduction of the auditory tracts in the brain stem, but also the correlations of the size of the cranium and brain which act as a volume conductor. (author).
Steinberger, Tomáš; Macháň, Radek; Hof, Martin
2014-01-01
Studies of lateral diffusion are used for the characterization of the dynamics of biological membranes. One of the techniques that can be used for this purpose is fluorescence correlation spectroscopy (FCS), which belongs to the single-molecule techniques. Unfortunately, FCS measurements, when performed in planar lipid systems, are associated with a few sources of inaccuracy in the determination of the lateral diffusion coefficient. The main problems are related to the imperfect positioning of the laser focus relative to the plane of the sample. Another source of inaccuracy is the requirement for external calibration of the detection volume size. This protocol introduces a calibration-free method called Z-scan fluorescence correlation spectroscopy (Z-scan FCS), which is based on the determination of the diffusion time and particle number in steps along the optical (z-) axis by sequential FCS measurements. Z-scan FCS could be employed for diffusion measurements in planar membrane model systems-supported phospholipid bilayers (SPBs) and giant unilamellar vesicles (GUVs) and also in biological membranes. A result from measurements in SPBs is also presented in the protocol as a principle example of the Z-scan technique.
Directory of Open Access Journals (Sweden)
Vivien Ainley
Full Text Available BACKGROUND: 'Self-objectification' is the tendency to experience one's body principally as an object, to be evaluated for its appearance rather than for its effectiveness. Within objectification theory, it has been proposed that self-objectification accounts for the poorer interoceptive awareness observed in women, as measured by heartbeat perception. Our study is, we believe, the first specifically to test this relationship. METHODOLOGY/PRINCIPAL FINDINGS: Using a well-validated and reliable heartbeat perception task, we measured interoceptive awareness in women and compared this with their scores on the Self-Objectification Questionnaire, the Self-Consciousness Scale and the Body Consciousness Questionnaire. Interoceptive awareness was negatively correlated with self-objectification. Interoceptive awareness, public body consciousness and private body consciousness together explained 31% of the variance in self-objectification. However, private body consciousness was not significantly correlated with interoceptive awareness, which may explain the many nonsignificant results in self-objectification studies that have used private body consciousness as a measure of body awareness. CONCLUSIONS/SIGNIFICANCE: We propose interoceptive awareness, assessed by heartbeat perception, as a measure of body awareness in self-objectification studies. Our findings have implications for those clinical conditions, in women, which are characterised by self-objectification and low interoceptive awareness, such as eating disorders.
Measuring two phase flow parameters using impedance cross-correlation flow meter
Muhamedsalih, Y.; Lucas, G.
2012-03-01
This paper describes the design and implementation of an impedance cross correlation flow meter which can be used in solids-water pipe flows to measure the local solids volume fraction distribution and the local solids velocity distribution. The system is composed of two arrays of electrodes, separated by an axial distance of 50 mm and each array contains eights electrodes mounted over the internal circumference of the pipe carrying the flow. Furthermore every electrode in each array can be selected to be either"excitation", "measurement" or "earth". Changing the electrode configuration leads to a change in the electric field, and hence in the region of the flow cross section which is interrogated. The local flow velocity in the interrogated region is obtained by cross correlation between the two electrode arrays. Additionally, the local solids volume fraction can be obtained from the mean mixture conductivity in the region under interrogation. The system is being integrated with a microcontroller to measure the velocity distribution of the solids and the volume fraction distribution of the solids in order to create a portable flow meter capable of measuring the multi-phase flow parameters without the need of a PC to control it. Integration of the product of the local solids volume fraction and the local solids velocity in the flow cross section enables the solids volumetric flow rate to be determined.
CORRELATION BETWEEN DURATION OF BOTTLE-FEEDING AND DENTAL ARCH MEASUREMENT IN DECIDUOUS DENTITION
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Meldo Mahniza
2015-06-01
Full Text Available The purpose of this study was to observe the correlation between duration of bottle feeding and dental arch measurement in deciduous dentition. Duration of bottle feeding was divided into 4 groups: ≤ 24 months, 25 – 36 months, 37 – 48 months, and > 48 months. The subjects were 120 kindergarten pupils, aged 3 – 5 years old. Measurements was done on the models of maxilla and mandible with digital caliper for the width and length of dental arch and using flexible curve for dental arch circumference. Pearson correlation showed a weak association for anterior arch width (r=0.206, posterior arch width (r=0.195, and anterior circumference (r=0.206 of maxilla and posterior arch width (r=0.279, anterior circumference (r=0.226 of mandible. One-way Anova was performed to analyze the differences of dental arch measurements among duration of bottle-feeding groups. The results showed that there were significant differences of dental arch measurements for anterior arch width of maxilla, posterior arch width of mandible, and anterior circumference of mandible (p<0,05.
Full-field Measurement of Deformation and Vibration using Digital Image Correlation
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Liang-Chih Chen
2015-05-01
Full Text Available The main intention of this study was to investigate the full-field measurement of de-formation and vibration using a program we developed for digital image correlation. Digital image correlation is a measuring method that can calculate the displacement of each point on an object by using recorded images. By capturing continuous images of the object in deformation or in motion, the displacements of feature points on the object can be tracked and used in calculations to determine the full-field deformation, strain and vibration of the object. We used the fast and simple algorithm in our program as the core, and conducted non-contact full-field displacement measurement by tracking feature points from images taken after motion. The measuring accuracy can be up to 0.1 pixel. Our experimental results show the technique to be very accurate and useful. We also applied this technique under conditions where an ordinary sensor could not be used.
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Alfredo Tibúrcio Nunes Pires
2012-09-01
Full Text Available Introduction: Fiber-reinforced composite posts (FRC posts have been used for tooth reinforcement after endodontic treatment. The mechanical characteristics of FRC posts can influence the clinical prognostic. Objective: The aim of this study was to evaluate the flexural strength and fracture resistance of commercially available FRC posts Material and methods: Fourteen human single-rooted premolars with completely formed apices were selected and received endodontic treatment. The specimens were divided into two groups related to the post system: i Group A – cylindrical-conical fiber-reinforced post (White post DC, FGM, and ii group B – conical fiber-reinforced post (EXACTO, Angelus. The fracture resistance was evaluated and two point bending tests were carried out. The glass fiber characteristics and the tag penetration of the luting material into the radicular dentin structure were evaluated through scanning electronic microscopy in an illustrative way. One-way ANOVA and Tukey’s HSD test (α = 0.05 were applied. Results: The values obtained for fracture resistance and two point bending test were, respectively, 399.29 N and 109.5 N for group A, and 386.25 N and 119.5 N for group B. No significant differences in strength values among the groups were found. Conclusion: There were no significant statistical differences between the two post groups regarding to fracture strength and two point bending strength. It can be concluded that the posts selected for this study performed satisfactorily in terms of mechanical properties so that they can be used for tooth reinforcement after endodontic treatment.
Kim, Howon; Lin, Shi-Zeng; Graf, Matthias J.; Miyata, Yoshinori; Nagai, Yuki; Kato, Takeo; Hasegawa, Yukio
2016-09-01
Local disordered nanostructures in an atomically thick metallic layer on a semiconducting substrate play significant and decisive roles in transport properties of two-dimensional (2D) conductive systems. We measured the electrical conductivity through a step of monoatomic height in a truly microscopic manner by using as a signal the superconducting pair correlation induced by the proximity effect. The transport property across a step of a one-monolayer Pb surface metallic phase, formed on a Si(111) substrate, was evaluated by inducing the pair correlation around the local defect and measuring its response, i.e., the reduced density of states at the Fermi energy using scanning tunneling microscopy. We found that the step resistance has a significant contribution to the total resistance on a nominally flat surface. Our study also revealed that steps in the 2D metallic layer terminate the propagation of the pair correlation. Superconductivity is enhanced between the first surface step and the superconductor-normal-metal interface by reflectionless tunneling when the step is located within a coherence length.
Institute of Scientific and Technical Information of China (English)
Xiaodan Li; Yongfeng Yin; Lance Fiondella; Yibin Zhou
2015-01-01
With progression of the digital age, the complexity of software continues to grow. As a result, methods to quantitatively assess characteristics of software have attracted significant atten-tion. These efforts have led to a large number of new measures such as coupling metrics, many of which seek to consider the impact of correlations between components and failures on ap-plication reliability. However, most of these approaches set the coupling parameters arbitrarily by making assumptions instead of utilizing experimental data and therefore may not accurately capture actual coupling between components of software applica-tion. Since the coupling matrix is often set arbitrarily, the existing approaches to assess software reliability considering component correlation fail to reflect the real degree of interaction and rela-tionships among software components. This paper presents an efficient approach to assess the software reliability considering correlated component failures, incorporating software architec-ture while considering actual internal coupling of software with an efficient approach based on multivariate Bernoul i (MVB) distribu-tion. The unified framework for software coupling measurement is informed by a comprehensive survey of frameworks for object-oriented and procedure-oriented software. This framework enables the extraction of more accurate coupling among components. The effectiveness of this method is il ustrated through an experimental study by applying it to a real-time software application.
Hallux Rigidus Grade Does Not Correlate With Foot and Ankle Ability Measure Score.
Nixon, Devon C; Lorbeer, Karly F; McCormick, Jeremy J; Klein, Sandra E; Johnson, Jeffrey E
2017-09-01
Classification systems for hallux rigidus imply that, as radiographic changes progress, symptoms will concurrently increase in severity. However, symptom intensity and radiographic severity can be discordant for many patients. We studied the correlation between hallux rigidus grades and the Foot and Ankle Ability Measure (FAAM) scores to better understand this relationship. We retrospectively reviewed weight-bearing radiographs of the foot and FAAM Activities of Daily Living (ADL) questionnaires for 84 patients with hallux rigidus. The Spearman rank coefficient was used to correlate clinical-radiographic hallux rigidus grade with FAAM ADL scores. In 84 patients, the clinical-radiographic grade for hallux rigidus showed no relationship with FAAM ADL score (r = -0.10; P = 0.36) but did show moderate correlation with patient age (r = 0.63; P < 0.001). Advancing radiographic changes in hallux rigidus did not correspond with patient symptoms as measured via FAAM ADL scores. The reliability and validity of current grading criteria for hallux rigidus may require further exploration. Level III.
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Alexander Miloff
2015-09-01
Full Text Available Social anxiety disorder (SAD and attentional bias are theoretically connected in cognitive behavioral therapeutic models. In fact, there is an emerging field focusing on modifying attentional bias as a stand-alone treatment. However, it is unclear to what degree these attentional biases are present before commencing treatment. The purpose of this study was to measure pre-treatment attentional bias in 153 participants diagnosed with SAD using a home-based Internet version of the dot-probe paradigm. Results showed no significant correlation for attentional bias (towards or away from negative words or faces and the self-rated version of the Liebowitz Social Anxiety Scale (LSAS-SR. However, two positive correlations were found for the secondary measures Generalized Anxiety Disorder 7 (GAD-7 and Patient Health Questionnaire 9 (PHQ-9. These indicated that those with elevated levels of anxiety and depression had a higher bias towards negative faces in neutral–negative and positive–negative valence combinations, respectively. The unreliability of the dot-probe paradigm and home-based Internet delivery are discussed to explain the lack of correlations between LSAS-SR and attentional bias. Changes to the dot-probe task are suggested that could improve reliability.
The Correlation between Different Facial Measurements and the Width of Maxillary Anterior Teeth
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Hassan Ahangari A.
2011-08-01
Full Text Available Statement of Problem: One of the most important procedures in the rehabilitation of an edentulous space in the anterior segment is the selection of an appropriate size of the anterior teeth in order to achieve the perfect esthetic results.Purpose: The purpose of this study was to examine the correlation between horizontal measurements of the face and width of the maxillary anterior teeth.Material and methods: In this descriptive-analytical and cross-sectional study, the face and teeth of the 77 subjects (39 women and 38 men aged between 20-30 with no facial and dental deformities were examined. Some horizontal dimensions of the face including IC (intercanthal, IP (interpupillary, BZW (bizygomatic width, IA (interalar, and ICm (Intercomussural width and perceived width of the teeth were calculated with AutoCAD software with 0.1 mm accuracy on the photos. The actual width of the teeth was calculated with a digital caliper by 0.1 mm accuracy on the maxillary casts. The data were analyzed in SPSS software using the Pearson correlation coefficient and t-test.Results: Except for the IC and the sum of the actual width of the six maxillary anterior teeth on the cast, the rest of the measurements were significantly different by gender ( p < 0.05. All the correlations between facial measurements and width of the teeth were bigger than when they were separated by gender. In women, the correlation between IC and the six anterior teeth in the front view (SANTF was the highest one ( r = 0.436, p = 0.005. However, the highest correlation was related to the ICm and SANTF in men. (r = 0.0501, p =0.001Conclusion: Within the limitation of this study, the results suggest that except for the BZW, the rest of the facial measurements including IC, IP, IA and ICm can be used as a preliminary criterion for determining the width of the maxillary anterior teeth of the edentulous patients.
Explicit Proof of Equivalence of Two-Point Functions in the Two Formalisms of Thermal Field Theory
Institute of Scientific and Technical Information of China (English)
ZHOU Bang-Rong
2002-01-01
We give an explicit proof of equivalence of the two-point function to one-loop order in the two formalisms of thermal λ3 theory based on the expressions in the real-time formalism and indicate that the key point of completing the proof is to separate carefully the imaginary part of the zero-temperature loop integralfrom relevant expressions and this fact will certainly be very useful for examination of the equivalent problem of two formalisms of thermal field theory in other theories, including the one of the propagators for scalar bound states in an NJL model.
Antar, B. N.
1976-01-01
A numerical technique is presented for locating the eigenvalues of two point linear differential eigenvalue problems. The technique is designed to search for complex eigenvalues belonging to complex operators. With this method, any domain of the complex eigenvalue plane could be scanned and the eigenvalues within it, if any, located. For an application of the method, the eigenvalues of the Orr-Sommerfeld equation of the plane Poiseuille flow are determined within a specified portion of the c-plane. The eigenvalues for alpha = 1 and R = 10,000 are tabulated and compared for accuracy with existing solutions.
Institute of Scientific and Technical Information of China (English)
Cheng Xiaoliang; Ying Weiting
2005-01-01
In this paper, we discuss the existence of solution of a nonlinear two-point boundary value problem with a positive parameter Q arising in the study of surfacetension-induced flows of a liquid metal or semiconductor. By applying the Schauder's fixed-point theorem, we prove that the problem admits a solution for 0 ≤ Q ≤ 14.306.It improves the result of 0 ≤ Q ＜ 1 in [2] and 0 ≤ Q ≤ 13.213 in [3].
Advanced digital speckle correlation method for strain measurement and nondestructive testing
Jin, Guan-chang; Bao, Nai-Keng; Chung, Po Sheun
1997-03-01
An advanced digital speckle correlation method (DSCM) is presented in this paper. The advantages of this method will not only improve the processing speed but also increase the measuring accuracy. Some mathematics tools are derived and a powerful computing program is developed for further applications. A new feature of the measuring sensitivity of DSCM that can be varied by different amplification of the optical arrangement is first presented. This advantage may be superior to those available in other optical metrology methods like Electronic Speckle Pattern Interferometry (ESPI) in micro-deformation measurements. The applications of strain measurement and nondestructive testing are described and the advantages of DSCM are obvious. Some examples of material behavior measurement and plastic strain measurement are presented. Due to the high sensitivity of DSCM, another potential application in nondestructive testing (NDT) is also described in this paper. From the application examples given, this advanced DSCM proves to be a new and effective optical strain sensing technique especially for small objects or micro-deformation measurements.
Correlation of cephalometric and anthropometric measures with obstructive sleep apnea severity
Borges, Paulo de Tarso M; Filho, Edson Santos Ferreira; Araujo, Telma Maria Evangelista de; Neto, Jose Machado Moita; Borges, Nubia Evangelista de Sa; Neto, Baltasar Melo; Campelo, Viriato; Paschoal, Jorge Rizzato; Li, Li M
2013-01-01
Summary Introduction: Patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) often have associated changes in craniofacial morphology and distribution of body fat, either alone or in combination. Aim: To correlate cephalometric and anthropometric measures with OSAHS severity by using the apnea-hypopnea index (AHI). Method: A retrospective cephalometry study of 93 patients with OSAHS was conducted from July 2010 to July 2012. The following measurements were evaluated: body mass index (BMI), neck circumference (NC), waist circumference (WC), hip circumference (HC), the angles formed by the cranial base and the maxilla (SNA) and the mandible (SNB), the difference between SNA and SNB (ANB), the distance from the mandibular plane to the hyoid bone (MP-H), the space between the base of the tongue and the posterior pharyngeal wall (PAS), and the distance between the posterior nasal spine and the tip of the uvula (PNS-P). Means, standard deviations, and Pearson's correlation coefficients were calculated and analyzed. Results: AHI correlated significantly with BMI (r = 0.207, p = 0.047), NC (r = 0.365, p = 0.000), WC (r = 0.337, p = 0.001), PNS-P (r = 0.282, p = 0.006), and MP-H (r = 0.235, p = 0.023). Conclusion: Anthropometric measurements (BMI, NC, and WC) and cephalometric measurements (MP-H and PNS-P) can be used as predictors of OSAHS severity. PMID:25992029
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Choi, Joon Young; Lee, Kyung Han; Kim, Sang Eun; Kim, Byung Tae; Hwang, Jee Hea; Lee, Byung Boong [Samsung Medical Center, Seoul (Korea, Republic of)
1997-07-01
An objective measure for the severity and progression is important for the management of lymphedema. To evaluate the usefulness of lympho-scintigraphy in this regard, we compared various quantitative indices from upper extremity lymphoscintigraphy with circumferential measurements, before and after physiotheraphy. Upper extremity lymphoscintigraphy was performed in 38 patients with unilateral postmastectomy lymphedema. Tc-99m antimony sulfide colloid (37 MBq) was injected s.c. into the second and third interdigital spaces. The injection sites were imaged immediately after injection. After standardized exercise for 15 min, upper extremity images were acquired 30 min, 1 hr and 2 hr after injection. The clearance of the injection site (CL), and % uptake in regional lymph nodes (%LN) and soft tissue of the extremity (i.e., the degree of dermal backflow) (%EXT) compared to the initial injection site were calculated. Circumference of each extremity was measured at 7 levels; the severity of lymphedema was expressed as the percentage difference of total circumferential difference (TCD) between healthy and edematous extremities compared to the total circumference of healthy extremity (%TCD). In 19 patients who received physiotherapy, the therapeutic effect was measured by % decrease of TCD (%DTCD) before and after therapy (Raines. et al., 1977). The quantitative indices calculated in the image at 2 hr p.i. had better correlation with either %TCD or %DTCD than those from earlier images (Table). The CL, %LN and %EXT of edematous extremity had a significant correlation with TCD. The %EXT was correlated best with either TCD or %DTCD. The results suggest that the %EXT which corresponds to the degree of dermal backflow may be a simple and useful quantitative index for evaluating the severity and progression in lymphedema and predicting the effect of therapy.
Lal, Nidhi; Mehra, Simmi; Lal, Vivek
2014-12-01
Ultrasonography is the diagnostic method of choice for visualization and rational work-up of abdominal organs. The dilatation of the common bile duct helps distinguish obstructive from non-obstructive causes of jaundice. Availability of normal measurements of the common bile duct is therefore important. There exists significant variations in the anthropometric features of various populations, regions and races. Study was conducted to obtain data on sonographically measured diameters of common bile duct in a series of normal Rajasthani population and to measure its correlation with age, sex and anthropometry. Cross-sectional hospital-based study conducted at Mahatma Gandhi Medical College and Hospital, Jaipur, India. Study included 200 participants with equal proportion belonging to either sex. Common bile duct was measured at three locations- at the porta hepatis, in the most distal aspect of head of pancreas and mid-way between these points. Anthropometric measurements including height, weight, chest circumference, circumference at transpyloric plane, circumference at umbilicus and circumference at hip were obtained using standard procedures. Univariable analysis with measures of frequency and standard deviation and bivariable analysis using correlation. Mean age of study subjects was 34.5 years (Range 18-85 years). Mean diameters of the common bile duct in the three locations were: proximal, 4.0 mm (SD 1.02 mm); middle, 4.1 mm (SD 1.01 mm); and distal, 4.2 mm (SD 1.01 mm) and overall mean for all measures 4.1 mm (SD 1.01 mm). Average diameter ranged from 2.0 mm to 7.9 mm, with 95 percent of the subjects having a diameter of less than 6 mm. We observed a statistically significant relation of common bile duct with age, along with a linear trend. There was no statistically significant difference in common bile duct diameter between male and female subjects. The diameter did not show any statistically significant correlation with any of the anthropometric
Decoherent histories and measurement of temporal correlation functions for Leggett-Garg inequalities
Halliwell, J. J.
2016-11-01
We consider two protocols for the measurement of the temporal correlation functions of a dichotomic variable Q appearing in Leggett-Garg-type inequalities. The protocols measure solely whether Q has the same or a different sign at the end of a given time interval, thereby measuring no more than is required for determination of the correlation function. They are inspired, in part, by a decoherent histories analysis of the two-time histories of Q , which yields a number of useful insights, although the protocols are ultimately expressed in macrorealistic form independent of quantum theory. The first type involves an ancilla coupled to the system with two sequential controlled-not (cnot) gates, and the two-time histories of the system (whose probabilities yield the correlation function) are determined in a single final time measurement of the ancilla. It is noninvasive for special choices of initial system states and partially invasive for more general choices. Modified Leggett-Garg-type inequalities which accommodate the partial invasiveness are discussed. The quantum picture of the protocol shows that for certain choices of the primary system initial state, the final state is unaffected by the two cnot gate interactions, hence the protocol is undetectable with respect to final system-state measurements, although it is still invasive at intermediate times. This invasiveness can be reduced with different choices of ancilla states and the protocol is then similar in flavor to a weak measurement. The second type of protocol is based on the fact that the behavior of Q over a time interval can be determined from knowledge of the dynamics together with a measurement of certain initial (or final) data. Its quantum version corresponds to the known fact that when sets of histories are decoherent, their probabilities may be expressed in terms of a record projector, hence the two-time histories in which Q has the same or a different sign can be determined by a single projective
Directory of Open Access Journals (Sweden)
R. Caballero-Águila
2014-01-01
Full Text Available The optimal least-squares linear estimation problem is addressed for a class of discrete-time multisensor linear stochastic systems subject to randomly delayed measurements with different delay rates. For each sensor, a different binary sequence is used to model the delay process. The measured outputs are perturbed by both random parameter matrices and one-step autocorrelated and cross correlated noises. Using an innovation approach, computationally simple recursive algorithms are obtained for the prediction, filtering, and smoothing problems, without requiring full knowledge of the state-space model generating the signal process, but only the information provided by the delay probabilities and the mean and covariance functions of the processes (signal, random parameter matrices, and noises involved in the observation model. The accuracy of the estimators is measured by their error covariance matrices, which allow us to analyze the estimator performance in a numerical simulation example that illustrates the feasibility of the proposed algorithms.
Non-contact in vivo measurement of ocular microtremor using laser speckle correlation metrology.
Kenny, E; Coakley, D; Boyle, G
2014-07-01
Ocular microtremor (OMT) is a small involuntary eye movement present in all subjects. In this paper we present the results of in vivo OMT measurement using a novel non-contact laser speckle technique. OMT signals have not previously been measured from the sclera using this laser speckle correlation technique. To verify the system's ability to record eye movements, it is first tested using a large angle eye rotation. Next, the system is tested with a group of 20 subjects and OMT parameters are extracted. The results of OMT measurements gave a mean frequency of 78 ± 3.86 Hz and peak-to-peak amplitude of 21.42 ± 7.01 µrad, these values are consistent with known values from eye-contacting methods.
Truth Studies Towards a Spin-Correlation Measurement in WW-Boson Production
Braun, Svende
2013-01-01
The precise measurement of the W Boson Pair Production provides an important test of the non-Abelian Structure of the Standard Model (SM) electroweak theory. Deviations of the production cross section or of kinematic distributions from their SM predictions could arise from anomalous triple gauge boson interactions or from new particles decaying into vector bosons and other possible exotic contributions. W Boson Pair Production is also an important source of background to the Higgs boson production [2]. In this report, Monte Carlo (MC) generator studies for a spin correlation measurement of the WW production are presented. Distortions of the (l; l) distribution due to the applied selection criteria are studied. Furthermore, the extrapolation of the measured cross sections to a common fiducial region and the associated systematic uncertainties are investigated.
Directory of Open Access Journals (Sweden)
Richard E. Tracy
2011-01-01
Full Text Available Cardiac myocytes are presumed to enlarge with left ventricular hypertrophy (LVH. This study correlates histologically measured myocytes with lean and fat body mass. Cases of LVH without coronary heart disease and normal controls came from forensic autopsies. The cross-sectional widths of myocytes in H&E-stained paraffin sections followed log normal distributions almost to perfection in all 104 specimens, with constant coefficient of variation across the full range of ventricular weight, as expected if myocytes of all sizes contribute proportionately to hypertrophy. Myocyte sizes increased with height. By regression analysis, height2.7 as a proxy for lean body mass and body mass index (BMI as a proxy for fat body mass, exerted equal effects in the multiple correlation with myocyte volume, and the equation rejected race and sex. In summary, myocyte sizes, as indexes of LVH, suggest that lean and fat body mass may contribute equally.
Estimation of the concordance correlation coefficient for repeated measures using SAS and R.
Carrasco, Josep L; Phillips, Brenda R; Puig-Martinez, Josep; King, Tonya S; Chinchilli, Vernon M
2013-03-01
The concordance correlation coefficient is one of the most common approaches used to assess agreement among different observers or instruments when the outcome of interest is a continuous variable. A SAS macro and R package are provided here to estimate the concordance correlation coefficient (CCC) where the design of the data involves repeated measurements by subject and observer. The CCC is estimated using U-statistics (UST) and variance components (VC) approaches. Confidence intervals and standard errors are reported along with the point estimate of the CCC. In the case of the VC approach, the linear mixed model output and variance components estimates are also provided. The performance of each function is shown by means of some examples with real data sets.
Energy Technology Data Exchange (ETDEWEB)
Wilson, R.J.; Jones, B.G.; Roy, R.P.
1980-02-01
An experimental study of the fluctuating velocity field, the fluctuating static wall pressure and the in-stream fluctuating static pressure in an annular turbulent air flow system with a radius ratio of 4.314 has been conducted. The study included direct measurements of the mean velocity profile, turbulent velocity field; fluctuating static wall pressure and in-stream fluctuating static pressure from which the statistical values of the turbulent intensity levels, power spectral densities of the turbulent quantities, the cross-correlation between the fluctuating static wall pressure and the fluctuating static pressure in the core region of the flow and the cross-correlation between the fluctuating static wall pressure and the fluctuating velocity field in the core region of the flow were obtained.
Correlates of objectively measured physical activity in 5-6 year old preschool children
DEFF Research Database (Denmark)
Olesen, L G; Kristensen, P L; Korsholm, L;
2015-01-01
The aim of this study was to identify gender specific physical activity correlates in Danish preschool children. METHODS: Cross--sectional study in Odense, Denmark. The gender specific models were based on data from 174 boys and 177 girls, 5--6 years of age and enrolled in 40 randomly selected...... preschools. Percentage of total daily time spent in moderate and vigorously physical activity (MVPA) was measured using ActiGraph accelerometers over 5 preschool days and 2 days off. Thirty--nine potential correlates of child MVPA across 5 domains were tested for associations with gender specific MVPA....... RESULTS: The gender specific models consistently identified motor coordination and the parents´ perceptions of their child´s activity preferences during free play were positively associated with MVPA. Days with rain or no preschool attendance were negatively associated with MVPA. For boys, rural area...
Measuring Collisionless Damping in Heliospheric Plasmas using Field-Particle Correlations
Klein, Kristopher G
2016-01-01
An innovative field-particle correlation technique is proposed that uses single-point measurements of the electromagnetic fields and particle velocity distribution functions to investigate the net transfer of energy from fields to particles associated with the collisionless damping of turbulent fluctuations in weakly collisional plasmas, such as the solar wind. In addition to providing a direct estimate of the local rate of energy transfer between fields and particles, it provides vital new information about the distribution of that energy transfer in velocity space. This velocity-space signature can potentially be used to identify the dominant collisionless mechanism responsible for the damping of turbulent fluctuations in the solar wind. The application of this novel field-particle correlation technique is illustrated using the simplified case of the Landau damping of Langmuir waves in an electrostatic 1D-1V Vlasov-Poisson plasma, showing that the procedure both estimates the local rate of energy transfer f...
Method for measuring radial impurity emission profiles using correlations of line integrated signals
Kuldkepp, M.; Brunsell, P. R.; Drake, J.; Menmuir, S.; Rachlew, E.
2006-04-01
A method of determining radial impurity emission profiles is outlined. The method uses correlations between line integrated signals and is based on the assumption of cylindrically symmetric fluctuations. Measurements at the reversed field pinch EXTRAP T2R show that emission from impurities expected to be close to the edge is clearly different in raw as well as analyzed data to impurities expected to be more central. Best fitting of experimental data to simulated correlation coefficients yields emission profiles that are remarkably close to emission profiles determined using more conventional techniques. The radial extension of the fluctuations is small enough for the method to be used and bandpass filtered signals indicate that fluctuations below 10kHz are cylindrically symmetric. The novel method is not sensitive to vessel window attenuation or wall reflections and can therefore complement the standard methods in the impurity emission reconstruction procedure.
Measuring anisotropy ellipse of atmospheric turbulence by intensity correlations of laser light.
Wang, Fei; Toselli, Italo; Li, Jia; Korotkova, Olga
2017-03-15
An experimental study has been performed of a laser beam propagating horizontally through the near-ground atmosphere above a grassy field at the University of Miami (UM) Coral Gables campus. The average intensity, scintillation index, and intensity correlation function are measured in the receiver plane for three channels with different turbulent conditions and at three different heights above the ground. Our results reveal that along short links (210 m) only the intensity correlation function captures the anisotropic information of turbulence, corresponding to the refractive index anisotropy ellipse of atmospheric fluctuations. In addition, we report an interesting phenomenon relating to turbulence eddy orientation near the ground. We confirmed that the experimental results are in agreement with the numerical simulations based on the multiple phase-screen method. Our findings provide an efficient method of determining the anisotropic parameters of atmospheric turbulence.
Bradley, Derek
2013-01-01
The implosion technique has been used to extend measurements of turbulent burning velocities over greater ranges of fuels and pressures. Measurements have been made up to 3.5 MPa and at strain rate Markstein numbers as low as 23. The implosion technique, with spark ignition at two opposite wall positions within a fan-stirred spherical bomb is capable of measuring turbulent burning velocities, at higher pressures than is possible with central ignition. Pressure records and schlieren high speed photography define the rate of burning and the smoothed area of the flame front. The first aim of the study was to extend the previous measurements with ethanol and propane-air, with further measurements over wider ranges of fuels and equivalence ratios with mixtures of hydrogen, methane, 10% hydrogen-90% methane, toluene, and i-octane, with air. The second aim was to study further the low turbulence regime in which turbulent burning co-exists with laminar flame instabilities. Correlations are presented of turbulent burning velocity normalised by the effective rms turbulent velocity acting on the flame front, ut=u0k , with the Karlovitz stretch factor, K, for different strain rate Markstein numbers, a decrease in which increases ut=u0k . Experimental correlations are presented for the present measurements, combined with previous ones. Different burning regimes are also identified, extending from that of mixed turbulence/laminar instability at low values of K to that at high values of K, in which ut=u0k is gradually reduced due to increasing localised flame extinctions. © 2012 The Combustion Institute.
Hu, I. H.; Senft-Grupp, S.; Hemond, H.
2014-12-01
The measurement of chemical fluxes between natural waters and their benthic sediments by most existing methods, such as benthic chambers and sediment core incubations, is slow, cumbersome, and often inaccurate. One promising new method for determining benthic fluxes is eddy correlation (EC), a minimally invasive, in situ technique based on high-speed velocity and concentration measurements. Widespread application of EC to a large range of chemicals of interest is currently limited, however, by the availability of rapid, high-resolution chemical sensors capable of precisely measuring concentrations at a point location and at sufficient speed (several Hz). A proof of concept spectrofluorometry instrument has been created that is capable of high-frequency concentration measurements of naturally fluorescent substances. Designed with the EC application in mind, the system utilizes optical fibers to transmit excitation and emission light, enabling in situ measurements at high spatial resolution. Emitted fluorescence light is passed through a tunable monochromator before reaching a photomultiplier tube; photons are quantified by a custom miniaturized, low-power photon counting circuit board. Preliminary results indicate that individual measurements made at 100 Hz of a 10 ppm humic acid solution were precise within 10%, thus yielding a precision of the order of +/- 1% in a second. Used in an EC system, this instrument will enable flux measurements of substances such as naturally occurring fluorescent dissolved organic material (FDOM). Measurement of fluxes of FDOM is significant in its own right, and also will allow the indirect measurement of the numerous other chemical fluxes that are associated with FDOM by using tracer techniques. The use of a tunable monochromator not only allows flexibility in detection wavelength, but also enables full wavelength scans of the emission spectrum, making the spectrofluorometer a dual-function device capable of both characterizing the
Camporese, Matteo; Botto, Anna
2017-04-01
Data assimilation is becoming increasingly popular in hydrological and earth system modeling, as it allows us to integrate multisource observation data in modeling predictions and, in doing so, to reduce uncertainty. For this reason, data assimilation has been recently the focus of much attention also for physically-based integrated hydrological models, whereby multiple terrestrial compartments (e.g., snow cover, surface water, groundwater) are solved simultaneously, in an attempt to tackle environmental problems in a holistic approach. Recent examples include the joint assimilation of water table, soil moisture, and river discharge measurements in catchment models of coupled surface-subsurface flow using the ensemble Kalman filter (EnKF). One of the typical assumptions in these studies is that the measurement errors are uncorrelated, whereas in certain situations it is reasonable to believe that some degree of correlation occurs, due for example to the fact that a pair of sensors share the same soil type. The goal of this study is to show if and how the measurement error correlations between different observation data play a significant role on assimilation results in a real-world application of an integrated hydrological model. The model CATHY (CATchment HYdrology) is applied to reproduce the hydrological dynamics observed in an experimental hillslope. The physical model, located in the Department of Civil, Environmental and Architectural Engineering of the University of Padova (Italy), consists of a reinforced concrete box containing a soil prism with maximum height of 3.5 m, length of 6 m, and width of 2 m. The hillslope is equipped with sensors to monitor the pressure head and soil moisture responses to a series of generated rainfall events applied onto a 60 cm thick sand layer overlying a sandy clay soil. The measurement network is completed by two tipping bucket flow gages to measure the two components (subsurface and surface) of the outflow. By collecting
Energy Technology Data Exchange (ETDEWEB)
Yue, Qiang [University of Tsukuba, Department of Neurosurgery, Institute of Clinical Medicine, Tsukuba Science City, Ibaraki (Japan)]|[West China Hospital of Sichuan University, Huaxi MR Research Center, Department of Radiology, Chengdu (China); Shibata, Yasushi; Kawamura, Hiraku; Matsumura, Akira [University of Tsukuba, Department of Neurosurgery, Institute of Clinical Medicine, Tsukuba Science City, Ibaraki (Japan); Isobe, Tomonori [Kitasato University, Department of Medical Technology, School of Allied Health Sciences, Minato, Tokyo (Japan); Anno, Izumi [University of Tsukuba, Department of Radiology, Institute of Clinical Medicine, Tsukuba, Ibaraki (Japan); Gong, Qi-Yong [West China Hospital of Sichuan University, Huaxi MR Research Center, Department of Radiology, Chengdu (China)]|[University of Liverpool, Division of Medical Imaging, Faculty of Medicine, Liverpool (United Kingdom)
2009-01-15
This study was aimed to investigate the relationship between quantitative proton magnetic resonance spectroscopy (1H-MRS) and pathological changes in meningioma. Twenty-two meningioma cases underwent single voxel 1H-MRS (point-resolved spectroscopy sequence, repetition time/echo time = 2,000 ms/68, 136, 272 ms). Absolute choline (Cho) concentration was calculated using tissue water as the internal reference and corrected according to intra-voxel cystic/necrotic parts. Pathological specimens were stained with MIB-1 antibody to measure cell density and proliferation index. Correlation analysis was performed between absolute Cho concentration and cell density and MIB-1 labeled proliferation index. Average Cho concentration of all meningiomas before correction was 2.95 {+-} 0.86 mmol/kg wet weight. It was increased to 3.23 {+-} 1.15 mmol/kg wet weight after correction. Average cell density of all meningiomas was 333 {+-} 119 cells/HPF, and average proliferation index was 2.93 {+-} 5.72%. A linear, positive correlation between cell density and Cho concentration was observed (r = 0.650, P = 0.001). After correction of Cho concentration, the correlation became more significant (r = 0.737, P < 0.001). However, no significant correlation between Cho concentration and proliferation index was found. There seemed to be a positive correlation trend after correction of Cho concentration but did not reach significant level. Absolute Cho concentration, especially Cho concentration corrected according to intra-voxel cystic/necrotic parts, reflects cell density of meningioma. (orig.)
de Thomaz, A A; Almeida, D B; Pelegati, V B; Carvalho, H F; Cesar, C L
2015-03-19
One of the most important properties of quantum dots (QDs) is their size. Their size will determine optical properties and in a colloidal medium their range of interaction. The most common techniques used to measure QD size are transmission electron microscopy (TEM) and X-ray diffraction. However, these techniques demand the sample to be dried and under a vacuum. This way any hydrodynamic information is excluded and the preparation process may alter even the size of the QDs. Fluorescence correlation spectroscopy (FCS) is an optical technique with single molecule sensitivity capable of extracting the hydrodynamic radius (HR) of the QDs. The main drawback of FCS is the blinking phenomenon that alters the correlation function implicating in a QD apparent size smaller than it really is. In this work, we developed a method to exclude blinking of the FCS and measured the HR of colloidal QDs. We compared our results with TEM images, and the HR obtained by FCS is higher than the radius measured by TEM. We attribute this difference to the cap layer of the QD that cannot be seen in the TEM images.
Measurements of multi-particle correlations and collective flow with the ATLAS detector
Bold, Tomasz; The ATLAS collaboration
2017-01-01
The measurement of flow harmonics of charged particles from v_2 to v_7 in Pb+Pb collisions in the wide range of transverse momentum and pseudorapidity provides not only a way to study the initial state of the nuclear collisions and soft particle collective dynamics, but also provides insight into jet quenching via the measurement of flow harmonics at high transverse momenta. The longitudinal fluctuations of the v_n and event-plane angles Psi_n are also presented. The longitudinal flow decorrelations have contributions from v_n-magnitude fluctuations and event plane twist. A four-particle correlator is used to separate these two effects. Results show both effects have a linear dependence on pseudorapidity separation from v_2 to v_5, and show a small but measurable variation with collision energy. While collectivity is well established in collisions involving heavy nuclei, its evidence in pp collisions is less clear. In order to assess the collective nature of multi-particle production, the correlation measurem...
Merry, C. J.
1979-01-01
A water sampling program was accomplished at Lake Powell, Utah, during June 1975 for correlation to multispectral data obtained with a 500-channel airborne spectroradiometer. Field measurements were taken of percentage of light transmittance, surface temperature, pH and Secchi disk depth. Percentage of light transmittance was also measured in the laboratory for the water samples. Analyses of electron micrographs and suspended sediment concentration data for four water samples located at Hite Bridge, Mile 168, Mile 150 and Bullfrog Bay indicated differences in the composition and concentration of the particulate matter. Airborne spectroradiometer multispectral data were analyzed for the four sampling locations. The results showed that: (1) as the percentage of light transmittance of the water samples decreased, the reflected radiance increased; and (2) as the suspended sediment concentration (mg/l) increased, the reflected radiance increased in the 1-80 mg/l range. In conclusion, valuable qualitative information was obtained on surface turbidity for the Lake Powell water spectra. Also, the reflected radiance measured at a wavelength of 0.58 micron was directly correlated to the suspended sediment concentration.
Measuring diffusion with polarization-modulation dual-focus fluorescence correlation spectroscopy.
Korlann, You; Dertinger, Thomas; Michalet, Xavier; Weiss, Shimon; Enderlein, Jörg
2008-09-15
We present a new technique, polarization-modulation dual-focus fluorescence correlation spectroscopy (pmFCS), based on the recently intro-duced dual-focus fluorescence correlation spectroscopy (2fFCS) to measure the absolute value of diffusion coefficients of fluorescent molecules at pico- to nanomolar concentrations. Analogous to 2fFCS, the new technique is robust against optical saturation in yielding correct values of the diffusion coefficient. This is in stark contrast to conventional FCS where optical saturation leads to an apparent decrease in the determined diffusion coefficient with increasing excitation power. However, compared to 2fFCS, the new technique is simpler to implement into a conventional confocal microscope setup and is compatible with cw-excitation, only needing as add-ons an electro-optical modulator and a differential interference contrast prism. With pmFCS, the measured diffusion coefficient (D) for Atto655 maleimide in water at 25?C is determined to be equal to (4.09 +/- 0.07) x 10(-6)cm(2)/s, in good agreement with the value of 4.04 x 10-6cm2/s as measured by 2fFCS.
DEFF Research Database (Denmark)
Lorke, Andreas; McGinnis, Daniel F.; Maeck, Andreas
2013-01-01
hours of continuous eddy-correlation measurements of sediment oxygen fluxes in an impounded river, we demonstrate that rotation of measured current velocities into streamline coordinates can be a crucial and necessary step in data processing under complex flow conditions in non-flat environments...... in the context of the theoretical concepts underlying eddy-correlation measurements and a set of recommendations for planning and analyses of flux measurements are derived....
Directory of Open Access Journals (Sweden)
Priscila G. Franco
2015-08-01
Full Text Available Background: Changes in the proprioceptive system are associated with aging. Proprioception is important to maintaining and/or recovering balance and to reducing the risk of falls.Objective:To compare the performance of young and active elderly adults in three proprioceptive tests.Method:Twenty-one active elderly participants (66.9±5.5 years and 21 healthy young participants (24.6±3.9 years were evaluated in the following tests: perception of position of the ankle and hip joints, perceived force level of the ankle joint, and two-point discrimination of the sole of the foot.Results:No differences (p>0.05 were found between groups for the joint position and perceived force level. On the other hand, the elderly participants showed lower sensitivity in the two-point discrimination (higher threshold when compared to the young participants (p < 0.01.Conclusion:Except for the cutaneous plantar sensitivity, the active elderly participants had maintained proprioception. Their physical activity status may explain similarities between groups for the joint position sense and perceived force level, however it may not be sufficient to prevent sensory degeneration with aging.
Exact two-point resistance, and the simple random walk on the complete graph minus N edges
Energy Technology Data Exchange (ETDEWEB)
Chair, Noureddine, E-mail: n.chair@ju.edu.jo
2012-12-15
An analytical approach is developed to obtain the exact expressions for the two-point resistance and the total effective resistance of the complete graph minus N edges of the opposite vertices. These expressions are written in terms of certain numbers that we introduce, which we call the Bejaia and the Pisa numbers; these numbers are the natural generalizations of the bisected Fibonacci and Lucas numbers. The correspondence between random walks and the resistor networks is then used to obtain the exact expressions for the first passage and mean first passage times on this graph. - Highlights: Black-Right-Pointing-Pointer We obtain exact formulas for the two-point resistance of the complete graph minus N edges. Black-Right-Pointing-Pointer We obtain also the total effective resistance of this graph. Black-Right-Pointing-Pointer We modified Schwatt's formula on trigonometrical power sum to suit our computations. Black-Right-Pointing-Pointer We introduced the generalized bisected Fibonacci and Lucas numbers: the Bejaia and the Pisa numbers. Black-Right-Pointing-Pointer The first passage and mean first passage times of the random walks have exact expressions.
The covariant and infrared-free graviton two-point function in de Sitter space-time
Pejhan, Hamed
2015-01-01
In this paper, the two-point function of linearized gravitons on de Sitter (dS) space is presented. Technically, respecting the dS ambient space notation, the field equation is given by the coordinate-independent Casimir operators of the de Sitter group. Analogous to the quantization of the electromagnetic field in Minkowski space, the field equation admits gauge solutions. The notation allows to exhibit the formalism of Gupta-Bleuler triplets for the present field in exactly the same manner as it occurs for the electromagnetic field. In this regard, centering on the traceless part, the field solution is written as a product of a generalized polarization tensor and a minimally coupled massless scalar field. Then, admitting a de Sitter-invariant vacuum through the so-called "Krein Space Quantization", the de Sitter fully covariant two-point function is calculated. This function is interestingly free of pathological large distance behavior (infrared divergence). Moreover, the pure-trace part (conformal sector) ...
Clinical applications of high-speed blood flow measurements with diffuse correlation spectroscopy
Parthasarathy, Ashwin B.; Baker, Wesley B.; Gannon, Kimberly; Mullen, Michael T.; Detre, John A.; Yodh, Arjun G.
2017-02-01
Diffuse Correlation Spectroscopy (DCS) is an increasingly popular non-invasive optical technique to clinically measure deep tissue blood flow, albeit at slow measurement rates of 0.5-1 Hz. We recently reported the development of a new `fast' DCS instrument that continuously measures blood flow at 50-100 Hz (simultaneously from 8 channels), using conventional DCS sources/detectors, and optimized software computations. A particularly interesting result was our ability to optically record pulsatile micro-vascular blood flow waveforms, and therein readily identify high frequency features such as the dicrotic notch. Here, we showcase the utility and potential of high-speed measurements of blood flow (and arterial blood pressure) in a few clinical applications. First, we employ the fast-DCS instrumentation to measure cerebral autoregulation (CVAR) dynamics. Cerebral autoregulation refers to the mechanism by which cerebral blood flow (CBF) is maintained during fluctuations in blood pressure; CVAR is impaired in the injured brain. We derive an index of autoregulation by measuring the rates of decrease (and recovery) of blood flow and blood pressure following a sudden, induced change in systemic blood pressure (e.g., bilateral thigh cuff deflation). Our pilot experiments in healthy volunteers show that DCS measured rates of micro-vascular regulation are comparable to conventional large vessel regulatory metrics (e.g., measured with transcranial Doppler ultrasound). Second, we utilized pulsatile blood flow oscillations in cerebral arteries to estimate the critical closing pressure (CrCP), i.e., the arterial blood pressure at which CBF approaches zero. Pilot experiments in healthy subjects show good agreement between CrCP measured with DCS and transcranial Doppler ultrasound.
Ying, Michael; Yung, Dennis M C; Ho, Karen K L
2008-01-01
This study aimed to develop a new two-dimensional (2-D) ultrasound thyroid volume estimation equation using three-dimensional (3-D) ultrasound as the standard of reference, and to compare the thyroid volume estimation accuracy of the new equation with three previously reported equations. 2-D and 3-D ultrasound examinations of the thyroid gland were performed in 150 subjects with normal serum thyrotropin (TSH, thyroid-stimulating hormone) and free thyroxine (fT4) levels (63 men and 87 women, age range: 17 to 71 y). In each subject, the volume of both thyroid lobes was measured by 3-D ultrasound. On 2-D ultrasound, the craniocaudal (CC), lateromedial (LM) and anteroposterior (AP) dimensions of the thyroid lobes were measured. The equation was derived by correlating the volume of the thyroid lobes measured with 3-D ultrasound and the product of the three dimensions measured with 2-D ultrasound using linear regression analysis, in 75 subjects without thyroid nodule. The accuracy of thyroid volume estimation of the new equation and the three previously reported equations was evaluated and compared in another 75 subjects (without thyroid nodule, n = 30; with thyroid nodule, n = 45). It is suggested that volume of thyroid lobe may be estimated as: volume of thyroid lobe = 0.38.(CC.LM.AP) + 1.76. Result showed that the new equation (16.9% to 36.1%) had a significantly smaller thyroid volume estimation error than the previously reported equations (20.8% to 54.9%) (p thyroid volume estimation error when thyroid glands with nodules were examined (p thyroid volume equation, 2-D ultrasound can be a useful alternative in thyroid volume measurement when 3-D ultrasound is not available.
Gazagnaire, Julia; Cobb, J. T.; Isaacs, Jason
2015-05-01
There is a desire in the Mine Counter Measure community to develop a systematic method to predict and/or estimate the performance of Automatic Target Recognition (ATR) algorithms that are detecting and classifying mine-like objects within sonar data. Ideally, parameters exist that can be measured directly from the sonar data that correlate with ATR performance. In this effort, two metrics were analyzed for their predictive potential using high frequency synthetic aperture sonar (SAS) images. The first parameter is a measure of contrast. It is essentially the variance in pixel intensity over a fixed partition of relatively small size. An analysis was performed to determine the optimum block size for this contrast calculation. These blocks were then overlapped in the horizontal and vertical direction over the entire image. The second parameter is the one-dimensional K-shape parameter. The K-distribution is commonly used to describe sonar backscatter return from range cells that contain a finite number of scatterers. An Ada-Boosted Decision Tree classifier was used to calculate the probability of classification (Pc) and false alarm rate (FAR) for several types of targets in SAS images from three different data sets. ROC curves as a function of the measured parameters were generated and the correlation between the measured parameters in the vicinity of each of the contacts and the ATR performance was investigated. The contrast and K-shape parameters were considered separately. Additionally, the contrast and K-shape parameter were associated with background texture types using previously labeled high frequency SAS images.
Scholz, Timo; Zech, Astrid; Wegscheider, Karl; Lezius, Susanne; Braumann, Klaus-Michael; Sehner, Susanne; Hollander, Karsten
2017-07-14
Measurement of the medial longitudinal foot arch in children is a controversial topic, as there are many different methods without a definite standard procedure. The purpose of this study was to 1) investigate intraday and interrater reliability regarding dynamic arch index and static arch height, 2) explore the correlation between both arch indices, and 3) examine the variation of the medial longitudinal arch at two different times of the day. Eighty-six children (mean ± SD age, 8.9 ± 1.9 years) participated in the study. Dynamic footprint data were captured with a pedobarographic platform. For static arch measurements, a specially constructed caliper was used to assess heel-to-toe length and dorsum height. A mixed model was established to determine reliability and variation. Reliability was found to be excellent for the static arch height index in sitting (intraday, 0.90; interrater, 0.80) and standing positions (0.88 and 0.85) and for the dynamic arch index (both 1.00). There was poor correlation between static and dynamic assessment of the medial longitudinal arch (standing dynamic arch index, r = -0.138; sitting dynamic arch index, r = -0.070). Static measurements were found to be significantly influenced by the time of day (P static arch height index is influenced by gender (P = .004), whereas dynamic arch index is influenced by side (P = .011) and body mass index (P static foot measurements are reliable for medial longitudinal foot arch assessment in children. The variation of static arch measurements during the day has to be kept in mind. For clinical purposes, static and dynamic arch data should be interpreted separately.
Directory of Open Access Journals (Sweden)
Martin Hof
2010-01-01
Full Text Available Fluorescence correlation spectroscopy (FCS is a single molecule technique used mainly for determination of mobility and local concentration of molecules. This review describes the specific problems of FCS in planar systems and reviews the state of the art experimental approaches such as 2-focus, Z-scan or scanning FCS, which overcome most of the artefacts and limitations of standard FCS. We focus on diffusion measurements of lipids and proteins in planar lipid membranes and review the contributions of FCS to elucidating membrane dynamics and the factors influencing it, such as membrane composition, ionic strength, presence of membrane proteins or frictional coupling with solid support.
Bai, Lu; Wang, Hongbo; Zhou, Jiangfan; Yang, Rong; Zhang, Hui
2014-11-01
In this paper, the aperture change of the aluminium alloy aerospace structure under real load is researched. Static experiments are carried on which is simulated the load environment of flight course. Compared with the traditional methods, through experiments results, it's proved that 3D digital speckle correlation method has good adaptability and precision on testing aperture change, and it can satisfy measurement on non-contact,real-time 3D deformation or stress concentration. The test results of new method is compared with the traditional method.
Measurement and Correlation of the Ionic Conductivity of Ionic Liquid-Molecular Solvent Solutions
Institute of Scientific and Technical Information of China (English)
LI,Wen-Jing; HAN,Bu-Xing; TAO,Ran-Ting; ZHANG,Zhao-Fu; ZHANG,Jian-Ling
2007-01-01
The ionic conductivity of the solutions formed from 1-n-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) or 1-n-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) and different molecular solvents (MSs) were measured at 298.15 K. The molar conductivity of the ionic liquids (ILs) increased dramatically with increasing concentration of the MSs. It was found that the molar conductivity of the IL in the solutions studied in this work could be well correlated by the molar conductivity of the neat ILs and the dielectric constant and molar volume of the MSs.
Energy Technology Data Exchange (ETDEWEB)
Park, Chan Ik [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul 151-744 (Korea, Republic of); Department of Cosmeceutical Science, Daegu Hanny University, Gyeongsangbuk-do 712-230 (Korea, Republic of); Shin, Moon Sam [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul 151-744 (Korea, Republic of); Kim, Hwayong [School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul 151-744 (Korea, Republic of)], E-mail: hwayongk@snu.ac.kr
2009-01-15
The supercritical technology has been considered as an appropriate alternative for separation of biomaterials from cosmetic, food, and pharmaceutical products. The solid solubility of biological compounds is the most important thermodynamic parameter in the supercritical extraction and purification. The equilibrium solubility of two biocides, climbazole, and triclocarban was measured in supercritical carbon dioxide with static method in the pressure range from (10 to 40) MPa and at temperatures equal to (313.2, 323.2, and 333.2) K. The experimental data were correlated by Peng-Robinson equation of state and quasi-chemical nonrandom lattice fluid model.
DEFF Research Database (Denmark)
Madsen, Daniel Esmarch; Hansen, Mikkel Fougt; Mørup, Steen
2008-01-01
We study the correlation between the superparamagnetic blocking temperature TB and the peak positions Tp observed in ac magnetization measurements for nanoparticles of different classes of magnetic materials. In general, Tp=α+βTB . The parameters α and β are different for the in-phase (χ') and out......-of-phase (χ") components and depend on the width σv of the log-normal volume distribution and the class of magnetic material (ferromagnetic/antiferromagnetic). Consequently, knowledge of both α and β is required if the anisotropy energy barrier KV and the attempt time To are to be reliably obtained from...
Directory of Open Access Journals (Sweden)
R. Caballero-Águila
2013-01-01
and each sensor noise are two-step cross-correlated. Under these assumptions and by an innovation approach, recursive algorithms for the optimal linear filter are derived by using the two basic estimation fusion structures; more specifically, both centralized and distributed fusion estimation algorithms are proposed. The accuracy of these estimators is measured by their error covariance matrices, which allow us to compare their performance in a numerical simulation example that illustrates the feasibility of the proposed filtering algorithms and shows a comparison with other existing filters.
NMR measurement of the magnetic field correlation function in porous media.
Cho, H; Song, Yi-Qiao
2008-01-18
The structure factor provides a fundamental characterization of porous and granular materials as it is the key for solid crystals via measurements of x-ray and neutron scattering. Here, we demonstrate that the structure factor of the granular and porous media can be approximated by the pair correlation function of the inhomogeneous internal magnetic field, which arises from the susceptibility difference between the pore filling liquid and the solid matrix. In-depth understanding of the internal field is likely to contribute to further development of techniques to study porous and granular media.
Measurement of q ˆ in Relativistic Heavy Ion Collisions using di-hadron correlations
Tannenbaum, M. J.
2017-08-01
The propagation of partons from hard scattering through the Quark Gluon Plasma produced in A+A collisions at RHIC and the LHC is represented in theoretical analyses by the transport coefficient q ˆ and predicted to cause both energy loss of the outgoing partons, observed as suppression of particles or jets with large transverse momentum pT, and broadening of the azimuthal correlations of the outgoing di-jets or di-hadrons from the outgoing parton-pair, which has not been observed. The widths of azimuthal correlations of di-hadrons with the same trigger particle pTt and associated pTa transverse momenta in p+p and Au+Au are so-far statistically indistinguishable as shown in recent as well as older di-hadron measurements and also with jet-hadron and hadron-jet measurements. The azimuthal width of the di-hadron correlations in p+p collisions, beyond the fragmentation transverse momentum, jT, is dominated by kT, the so-called intrinsic transverse momentum of a parton in a nucleon, which can be measured. The broadening should produce a larger kT in A+A than in p+p collisions. The present work introduces the observation that the kT measured in p+p collisions for di-hadrons with pTt and pTa must be reduced to compensate for the energy loss of both the trigger and away parent partons when comparing to the kT measured with the same di-hadron pTt and pTa in Au+Au collisions. This idea is applied to a recent STAR di-hadron measurement, with result = 2.1 ± 0.6 GeV2. This is more precise but in agreement with a theoretical calculation of =14-14+42 GeV2 using the same data. Assuming a length ≈ 7 fm for central Au+Au collisions the present result gives q ˆ ≈ 0.30 ± 0.09 GeV2/fm, in fair agreement with the JET collaboration result from single hadron suppression of q ˆ ≈ 1.2 ± 0.3 GeV2/fm at an initial time τ0 = 0.6 fm/c in Au+Au collisions at √{sNN} = 200 GeV.
Measuring the Galaxy-Galaxy-Mass Three-point Correlation Function with Weak Gravitational Lensing
Johnston, D E
2006-01-01
We discuss the galaxy-galaxy-mass three-point correlation function and show how to measure it with weak gravitational lensing. The method entails choosing a large of pairs of foreground lens galaxies and constructing a mean shear map with respect to their axis, by averaging the ellipticities of background source galaxies. An average mass map can be reconstructed from this shear map and this will represent the average mass distribution around pairs of galaxies. We show how this mass map is related to the projected galaxy-galaxy-mass three-point correlation function. Using a large N-body dark matter simulation populated with galaxies using the Halo Occupation Distribution (HOD) bias prescription, we compute these correlation functions, mass maps, and shear maps. The resultant mass maps are distinctly bimodal, tracing the galaxy centers and remaining anisotropic up to scales much larger than the galaxy separation. At larger scales, the shear is approximately tangential about the center of the pair but with small...
Measurement of azimuthal correlations between D mesons and charged hadrons with ALICE at the LHC
Directory of Open Access Journals (Sweden)
Colamaria Fabio
2014-01-01
Full Text Available The comparison of angular correlations between charmed mesons and charged hadrons produced in pp, p-Pb and Pb-Pb collisions can give insight into the mechanisms through which charm quarks lose energy in a QGP medium, produced in ultra-relativistic heavy-ion collisions, and can help to recognize possible modifications of their hadronization induced by the presence of the QGP. The analysis of pp and p-Pb data and the comparison with predictions from pQCD calculations, besides constituting the necessary reference for interpreting Pb-Pb data, can provide relevant information on charm production and fragmentation processes. In addition, possible differences between the results from pp and p-Pb collisions can give information on the presence of cold nuclear matter effects, affecting the charm production and hadronization in the latter collision system. A study of azimuthal correlations between D0, D+, and D*+ mesons and charged hadrons in pp collisions at √s = 7 TeV and p-Pb collisions at √sNN = 5.02 TeV are presented. D mesons were reconstructed from their hadronic decays at central rapidity in the transverse-momentum range 3 ≤ pTD ≤ 16 GeV/c and were correlated to charged particles reconstructed in the pseudorapidity range |η| < 0.8. Perspectives for the measurement in Pb-Pb collisions at √sNN = 2.76 TeV will also be presented.
Correlation of Spectral Solar Irradiance with solar activity as measured by VIRGO
Wehrli, C; Shapiro, A I
2013-01-01
Context. The variability of Solar Spectral Irradiance over the rotational period and its trend over the solar activity cycle are important for understanding the Sun-Earth connection as well as for observational constraints for solar models. Recently the SIM experiment on SORCE has published an unexpected negative correlation with Total Solar Irradiance of the visible spectral range. It is compensated by a strong and positive variability of the near UV range. Aims. We aim to verify whether the anti-correlated SIM/SORCE-trend in the visible can be confirmed by independent observations of the VIRGO experiment on SOHO. The challenge of all space experiments measuring solar irradiance are sensitivity changes of their sensors due to exposure to intense UV radiation, which are difficult to assess in orbit. Methods. We analyze a 10-year time series of VIRGO sun photometer data between 2002 and 2012. The variability of Spectral Solar Irradiance is correlated with the variability of the Total Solar Irradiance, which is...
Reese, Hannah E; Scahill, Lawrence; Peterson, Alan L; Crowe, Katherine; Woods, Douglas W; Piacentini, John; Walkup, John T; Wilhelm, Sabine
2014-03-01
In addition to motor and/or vocal tics, many individuals with Tourette syndrome (TS) or chronic tic disorder (CTD) report frequent, uncomfortable sensory phenomena that immediately precede the tics. To date, examination of these premonitory sensations or urges has been limited by inconsistent assessment tools. In this paper, we examine the psychometric properties of a nine-item self-report measure, the Premonitory Urge to Tic Scale (PUTS) and examine the characteristics and correlates of the premonitory urge to tic in a clinical sample of 122 older adolescents and adults with TS or CTD. The PUTS demonstrated adequate internal consistency, temporal stability, and concurrent validity. Premonitory urges were endorsed by the majority of individuals. Most individuals reported some relief from the urges after completing a tic and being able to stop their tics even if only temporarily. Degree of premonitory urges was not significantly correlated with age, and we did not observe any gender differences. Degree of premonitory urges was significantly correlated with estimated IQ and tic severity, but not severity of comorbid obsessive-compulsive disorder or attention-deficit hyperactivity disorder. Also, it was not related to concomitant medication status. These findings represent another step forward in our understanding of the premonitory sensations associated with TS and CTD.
Han, Fang; Hou, Ningning; Miao, Wei; Sun, Xiaodong
2013-08-01
To determine whether intrarenal arterial resistance index (RI) value is related to increased urinary albumin excretion and whether RI value is an independent good indicator to evaluate early renal damage in nonhypertensive, nondiabetic obese subjects. Sixty-four nonhypertensive, nondiabetic obese patients (OB) and 35 age- and sex-matched normal healthy subjects were involved in this study. Clinical characteristics and blood biochemistry of all the subjects were measured. Urinary albumin/creatinine ratio (ACR) and sonographic evaluation of renal blood flow were determined. ACR and interlobar arterial RI were significantly higher in obese patients than those of normal healthy subjects. Interlobar arterial RI value was higher in patients with microalbuminuria than those with normoalbuminuria. Correlation analysis showed interlobar artery RI value had a positive correlation with ACR (r = 0.615, p < 0.01) and plasma free fatty acids (FFAs, r = 0.407, p < 0.01). ACR had a positive correlation with BMI (r = 0.380, p < 0.01), waist circumference (r = 0.414, p < 0.01), plasma FFAs (r = 0.537, p < 0.01). Multivariate regression analyses showed that ACR was best predicted by interlobar artery RI value even when body mass index, waist circumference, FFAs, and high-sensitive C reaction protein were added in the statistical analysis. Interlobar arterial RI may be an independent predictor of microalbuminuria in nonhypertensive, nondiabetic obese patients, and interlobar arterial RI could be a useful tool for assessment early renal damage in obese patients.
In-plane displacement and strain measurements using a camera phone and digital image correlation
Yu, Liping; Pan, Bing
2014-05-01
In-plane displacement and strain measurements of planar objects by processing the digital images captured by a camera phone using digital image correlation (DIC) are performed in this paper. As a convenient communication tool for everyday use, the principal advantages of a camera phone are its low cost, easy accessibility, and compactness. However, when used as a two-dimensional DIC system for mechanical metrology, the assumed imaging model of a camera phone may be slightly altered during the measurement process due to camera misalignment, imperfect loading, sample deformation, and temperature variations of the camera phone, which can produce appreciable errors in the measured displacements. In order to obtain accurate DIC measurements using a camera phone, the virtual displacements caused by these issues are first identified using an unstrained compensating specimen and then corrected by means of a parametric model. The proposed technique is first verified using in-plane translation and out-of-plane translation tests. Then, it is validated through a determination of the tensile strains and elastic properties of an aluminum specimen. Results of the present study show that accurate DIC measurements can be conducted using a common camera phone provided that an adequate correction is employed.
Beberniss, Timothy J.; Ehrhardt, David A.
2017-03-01
A review of the extensive studies on the feasibility and practicality of utilizing high-speed 3 dimensional digital image correlation (3D-DIC) for various random vibration measurement applications is presented. Demonstrated capabilities include finite element model updating utilizing full-field 3D-DIC static displacements, modal survey natural frequencies, damping, and mode shape results from 3D-DIC are baselined against laser Doppler vibrometry (LDV), a comparison between foil strain gage and 3D-DIC strain, and finally the unique application to a high-speed wind tunnel fluid-structure interaction study. Results show good agreement between 3D-DIC and more traditional vibration measurement techniques. Unfortunately, 3D-DIC vibration measurement is not without its limitations, which are also identified and explored in this study. The out-of-plane sensitivity required for vibration measurement for 3D-DIC is orders of magnitude less than LDV making higher frequency displacements difficult to sense. Furthermore, the digital cameras used to capture the DIC images have no filter to eliminate temporal aliasing of the digitized signal. Ultimately DIC is demonstrated as a valid alternative means to measure structural vibrations while one unique application achieves success where more traditional methods would fail.
Ning, Z Y; Fu, M Q; Shi, T W; Guo, Y; Wei, X L; Gao, S; Chen, Q
2014-07-11
The relationship between property and structure is one of the most important fundamental questions in the field of nanomaterials and nanodevices. Understanding the multiproperties of a given nano-object also aids in the development of novel nanomaterials and nanodevices. In this paper, we develop for the first time a comprehensive platform for in situ multiproperty measurements of individual nanomaterials using a scanning electron microscope (SEM). Mechanical, electrical, electromechanical, optical, and photoelectronic properties of individual nanomaterials, with lengths that range from less than 200 nm to 20 μm, can be measured in situ with an SEM on the platform under precisely controlled single-axial strain and environment. An individual single-walled carbon nanotube (SWCNT) was measured on the platform. Three-terminal electronic measurements in a field effect transistor structure showed that the SWCNT was semiconducting and agreed with the structure characterization by transmission electron microscopy after the in situ measurements. Importantly, we observed a bandgap increase of this SWCNT with increasing axial strain, and for the first time, the experimental results quantitatively agree with theoretical predictions calculated using the chirality of the SWCNT. The vibration performance of the SWCNT, a double-walled CNT, and a triple-walled CNT were also studied as a function of axial strain, and were proved to be in good agreement with classical beam theory, although the CNTs only have one, two, or three atomic layers, respectively. Our platform has wide applications in correlating multiproperties of the same individual nanostructures with their atomic structures.