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Sample records for correlated input variables

  1. Rank correlation plots for use with correlated input variables in simulation studies

    Energy Technology Data Exchange (ETDEWEB)

    Iman, R.L.; Davenport, J.M.

    1980-11-01

    A method for inducing a desired rank correlation matrix on multivariate input vectors for simulation studies has recently been developed by Iman and Conover (SAND 80-0157). The primary intention of this procedure is to produce correlated input variables for use with computer models. Since this procedure is distribution free and allows the exact marginal distributions to remain intact, it can be used with any marginal distributions for which it is reasonable to think in terms of correlation. A series of rank correlation plots based on this procedure when the marginal distributions are normal, lognormal, uniform, and loguniform is presented. These plots provide a convenient tool for both aiding the modeler in determining the degree of dependence among variables (rather than guessing) and communicating with the modeler the effect of different correlation assumptions. 12 figures, 10 tables.

  2. Analysis of input variables of an artificial neural network using bivariate correlation and canonical correlation

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Valter Magalhaes; Pereira, Iraci Martinez, E-mail: valter.costa@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The monitoring of variables and diagnosis of sensor fault in nuclear power plants or processes industries is very important because a previous diagnosis allows the correction of the fault and, like this, to prevent the production stopped, improving operator's security and it's not provoking economics losses. The objective of this work is to build a set, using bivariate correlation and canonical correlation, which will be the set of input variables of an artificial neural network to monitor the greater number of variables. This methodology was applied to the IEA-R1 Research Reactor at IPEN. Initially, for the input set of neural network we selected the variables: nuclear power, primary circuit flow rate, control/safety rod position and difference in pressure in the core of the reactor, because almost whole of monitoring variables have relation with the variables early described or its effect can be result of the interaction of two or more. The nuclear power is related to the increasing and decreasing of temperatures as well as the amount radiation due fission of the uranium; the rods are controls of power and influence in the amount of radiation and increasing and decreasing of temperatures; the primary circuit flow rate has the function of energy transport by removing the nucleus heat. An artificial neural network was trained and the results were satisfactory since the IEA-R1 Data Acquisition System reactor monitors 64 variables and, with a set of 9 input variables resulting from the correlation analysis, it was possible to monitor 51 variables. (author)

  3. Risk assessment of finishing beef cattle in feedlot: slaughter weights and correlation amongst input variables

    Directory of Open Access Journals (Sweden)

    Paulo Santana Pacheco

    2014-02-01

    Full Text Available The objective of this study was to evaluate the risk associated with finishing crossbred Charolais × Nellore steers in feedlot at different slaughter weights (425, 467 or 510 kg, considering or disregarding the correlation amongst random input variables. Data were collected from 2004 to 2010 and used in the simulation of the financial indicator Net Present Value (NPV. Animals slaughtered with 425, 467 or 510 kg were fed diets containing a roughage:concentrate ratio of 60:40 for 30, 65 and 94 days, respectively. In the simulation of NPV, a Latin Hypercube type of sampling was used, running 2000 interactions. An analysis of stochastic dominance of first and second orders was carried out as well as the Kolmogorov-Smirnov asymptotic test (to check for differences between pairs of curves of cumulative distributions, followed by sensitivity analysis using stepwise multivariate regression. Simulations of NPV considering the correlation amongst the input variables produced more consistent estimates of this financial indicator than simulations that disregarded it. The risk analysis showed that 467 kg slaughter weight presented the lowest risk for finishing cattle in feedlots when compared with 425 and 510 kg. The most important variables influencing the NVP are the prices of feeder and finished steers, initial and final weights, concentrate and roughage costs, and minimum rate of attractiveness; therefore, farmers should pay particular attention to these variables when making the decision of whether or not to use feedlot to finish beef cattle.

  4. A Non-Simulation Based Method for Inducing Pearson’s Correlation Between Input Random Variables

    Science.gov (United States)

    2008-04-23

    Thanks to Dr. Steven Book of MCR for his help in obtaining copies of several papers on correlation modules, without which this paper would not have been...risks, not estimating variation SWBS Description Upside Probable Downside 000 Administration 100 Hull 200 Propulsion 300 Electric Plant 400 Electonics ...Systems 500 Auxillary Systems 600 Outfit & Furnishings 700 Weapons 800 Integration & Engineering 900 Ship Assembly & Support Total SWBS Description

  5. Statistical identification of effective input variables. [SCREEN

    Energy Technology Data Exchange (ETDEWEB)

    Vaurio, J.K.

    1982-09-01

    A statistical sensitivity analysis procedure has been developed for ranking the input data of large computer codes in the order of sensitivity-importance. The method is economical for large codes with many input variables, since it uses a relatively small number of computer runs. No prior judgemental elimination of input variables is needed. The sceening method is based on stagewise correlation and extensive regression analysis of output values calculated with selected input value combinations. The regression process deals with multivariate nonlinear functions, and statistical tests are also available for identifying input variables that contribute to threshold effects, i.e., discontinuities in the output variables. A computer code SCREEN has been developed for implementing the screening techniques. The efficiency has been demonstrated by several examples and applied to a fast reactor safety analysis code (Venus-II). However, the methods and the coding are general and not limited to such applications.

  6. Effect of correlated inputs on DO (dissolved oxygen) uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Brown, L.C.; Song, Q.

    1988-06-01

    Although uncertainty analysis has been discussed in recent water-quality-modeling literature, much of the work has assumed that all input variables and parameters are mutually independent. The objective of this paper is to evaluate the importance of correlation among the model inputs in the study of model-output uncertainty. The model used for demonstrating the influence of input-variable correlation is the Streeter-Phelps dissolved oxygen equation. The model forms the basis of many of the water-quality models currently in use and the relationships between model inputs and output-state variables are well understood.

  7. Significance of input correlations in striatal function.

    Directory of Open Access Journals (Sweden)

    Man Yi Yim

    2011-11-01

    Full Text Available The striatum is the main input station of the basal ganglia and is strongly associated with motor and cognitive functions. Anatomical evidence suggests that individual striatal neurons are unlikely to share their inputs from the cortex. Using a biologically realistic large-scale network model of striatum and cortico-striatal projections, we provide a functional interpretation of the special anatomical structure of these projections. Specifically, we show that weak pairwise correlation within the pool of inputs to individual striatal neurons enhances the saliency of signal representation in the striatum. By contrast, correlations among the input pools of different striatal neurons render the signal representation less distinct from background activity. We suggest that for the network architecture of the striatum, there is a preferred cortico-striatal input configuration for optimal signal representation. It is further enhanced by the low-rate asynchronous background activity in striatum, supported by the balance between feedforward and feedback inhibitions in the striatal network. Thus, an appropriate combination of rates and correlations in the striatal input sets the stage for action selection presumably implemented in the basal ganglia.

  8. Sensitivity analysis of a sound absorption model with correlated inputs

    Science.gov (United States)

    Chai, W.; Christen, J.-L.; Zine, A.-M.; Ichchou, M.

    2017-04-01

    Sound absorption in porous media is a complex phenomenon, which is usually addressed with homogenized models, depending on macroscopic parameters. Since these parameters emerge from the structure at microscopic scale, they may be correlated. This paper deals with sensitivity analysis methods of a sound absorption model with correlated inputs. Specifically, the Johnson-Champoux-Allard model (JCA) is chosen as the objective model with correlation effects generated by a secondary micro-macro semi-empirical model. To deal with this case, a relatively new sensitivity analysis method Fourier Amplitude Sensitivity Test with Correlation design (FASTC), based on Iman's transform, is taken into application. This method requires a priori information such as variables' marginal distribution functions and their correlation matrix. The results are compared to the Correlation Ratio Method (CRM) for reference and validation. The distribution of the macroscopic variables arising from the microstructure, as well as their correlation matrix are studied. Finally the results of tests shows that the correlation has a very important impact on the results of sensitivity analysis. Assessment of correlation strength among input variables on the sensitivity analysis is also achieved.

  9. Correlated neural variability in persistent state networks.

    Science.gov (United States)

    Polk, Amber; Litwin-Kumar, Ashok; Doiron, Brent

    2012-04-17

    Neural activity that persists long after stimulus presentation is a biological correlate of short-term memory. Variability in spiking activity causes persistent states to drift over time, ultimately degrading memory. Models of short-term memory often assume that the input fluctuations to neural populations are independent across cells, a feature that attenuates population-level variability and stabilizes persistent activity. However, this assumption is at odds with experimental recordings from pairs of cortical neurons showing that both the input currents and output spike trains are correlated. It remains unclear how correlated variability affects the stability of persistent activity and the performance of cognitive tasks that it supports. We consider the stochastic long-timescale attractor dynamics of pairs of mutually inhibitory populations of spiking neurons. In these networks, persistent activity was less variable when correlated variability was globally distributed across both populations compared with the case when correlations were locally distributed only within each population. Using a reduced firing rate model with a continuum of persistent states, we show that, when input fluctuations are correlated across both populations, they drive firing rate fluctuations orthogonal to the persistent state attractor, thereby causing minimal stochastic drift. Using these insights, we establish that distributing correlated fluctuations globally as opposed to locally improves network's performance on a two-interval, delayed response discrimination task. Our work shows that the correlation structure of input fluctuations to a network is an important factor when determining long-timescale, persistent population spiking activity.

  10. Variable angle correlation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y K [Univ. of California, Berkeley, CA (United States)

    1994-05-01

    In this dissertation, a novel nuclear magnetic resonance (NMR) technique, variable angle correlation spectroscopy (VACSY) is described and demonstrated with {sup 13}C nuclei in rapidly rotating samples. These experiments focus on one of the basic problems in solid state NMR: how to extract the wealth of information contained in the anisotropic component of the NMR signal while still maintaining spectral resolution. Analysis of the anisotropic spectral patterns from poly-crystalline systems reveal information concerning molecular structure and dynamics, yet in all but the simplest of systems, the overlap of spectral patterns from chemically distinct sites renders the spectral analysis difficult if not impossible. One solution to this problem is to perform multi-dimensional experiments where the high-resolution, isotropic spectrum in one dimension is correlated with the anisotropic spectral patterns in the other dimensions. The VACSY technique incorporates the angle between the spinner axis and the static magnetic field as an experimental parameter that may be incremented during the course of the experiment to help correlate the isotropic and anisotropic components of the spectrum. The two-dimensional version of the VACSY experiments is used to extract the chemical shift anisotropy tensor values from multi-site organic molecules, study molecular dynamics in the intermediate time regime, and to examine the ordering properties of partially oriented samples. The VACSY technique is then extended to three-dimensional experiments to study slow molecular reorientations in a multi-site polymer system.

  11. Linear Regression in High Dimension and/or for Correlated Inputs

    Science.gov (United States)

    Jacques, J.; Fraix-Burnet, D.

    2014-12-01

    Ordinary least square is the common way to estimate linear regression models. When inputs are correlated or when they are too numerous, regression methods using derived inputs directions or shrinkage methods can be efficient alternatives. Methods using derived inputs directions build new uncorrelated variables as linear combination of the initial inputs, whereas shrinkage methods introduce regularization and variable selection by penalizing the usual least square criterion. Both kinds of methods are presented and illustrated thanks to the R software on an astronomical dataset.

  12. Balanced synaptic input shapes the correlation between neural spike trains.

    Science.gov (United States)

    Litwin-Kumar, Ashok; Oswald, Anne-Marie M; Urban, Nathaniel N; Doiron, Brent

    2011-12-01

    Stimulus properties, attention, and behavioral context influence correlations between the spike times produced by a pair of neurons. However, the biophysical mechanisms that modulate these correlations are poorly understood. With a combined theoretical and experimental approach, we show that the rate of balanced excitatory and inhibitory synaptic input modulates the magnitude and timescale of pairwise spike train correlation. High rate synaptic inputs promote spike time synchrony rather than long timescale spike rate correlations, while low rate synaptic inputs produce opposite results. This correlation shaping is due to a combination of enhanced high frequency input transfer and reduced firing rate gain in the high input rate state compared to the low state. Our study extends neural modulation from single neuron responses to population activity, a necessary step in understanding how the dynamics and processing of neural activity change across distinct brain states.

  13. Balanced synaptic input shapes the correlation between neural spike trains.

    Directory of Open Access Journals (Sweden)

    Ashok Litwin-Kumar

    2011-12-01

    Full Text Available Stimulus properties, attention, and behavioral context influence correlations between the spike times produced by a pair of neurons. However, the biophysical mechanisms that modulate these correlations are poorly understood. With a combined theoretical and experimental approach, we show that the rate of balanced excitatory and inhibitory synaptic input modulates the magnitude and timescale of pairwise spike train correlation. High rate synaptic inputs promote spike time synchrony rather than long timescale spike rate correlations, while low rate synaptic inputs produce opposite results. This correlation shaping is due to a combination of enhanced high frequency input transfer and reduced firing rate gain in the high input rate state compared to the low state. Our study extends neural modulation from single neuron responses to population activity, a necessary step in understanding how the dynamics and processing of neural activity change across distinct brain states.

  14. Are Financial Variables Inputs in Delivered Production Functions? Are Financial Variables Inputs in Delivered Production Functions?

    Directory of Open Access Journals (Sweden)

    Miguel Kiguel

    1995-03-01

    Full Text Available Fischer's classic (1974 paper develops conditions under which it is appropriate to use money as an input in a 'delivered' production function. In this paper, we extend Fischer's model I (the Baumol-Tobin inventory approach by incorporating credit into the analysis. Our investigation of the extended model brings out a very restrictive but necessary implicit assumption employed by Fischer to treat money as an input. Namely. that there exists a binding constraint on the use of money! A similar result holds for our more general model. Fischer's classic (1974 paper develops conditions under which it is appropriate to use money as an input in a 'delivered' production function. In this paper, we extend Fischer's model I (the Baumol-Tobin inventory approach by incorporating credit into the analysis. Our investigation of the extended model brings out a very restrictive but necessary implicit assumption employed by Fischer to treat money as an input. Namely. that there exists a binding constraint on the use of money! A similar result holds for our more general model.

  15. Variable Input and the Acquisition of Plural Morphology

    Science.gov (United States)

    Miller, Karen L.; Schmitt, Cristina

    2012-01-01

    The present article examines the effect of variable input on the acquisition of plural morphology in two varieties of Spanish: Chilean Spanish, where the plural marker is sometimes omitted due to a phonological process of syllable final /s/ lenition, and Mexican Spanish (of Mexico City), with no such lenition process. The goal of the study is to…

  16. Sensitivity Analysis of the ALMANAC Model's Input Variables

    Institute of Scientific and Technical Information of China (English)

    XIE Yun; James R.Kiniry; Jimmy R.Williams; CHEN You-min; LIN Er-da

    2002-01-01

    Crop models often require extensive input data sets to realistically simulate crop growth. Development of such input data sets can be difficult for some model users. The objective of this study was to evaluate the importance of variables in input data sets for crop modeling. Based on published hybrid performance trials in eight Texas counties, we developed standard data sets of 10-year simulations of maize and sorghum for these eight counties with the ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria) model. The simulation results were close to the measured county yields with relative error only 2.6%for maize, and - 0.6% for sorghum. We then analyzed the sensitivity of grain yield to solar radiation, rainfall, soil depth, soil plant available water, and runoff curve number, comparing simulated yields to those with the original, standard data sets. Runoff curve number changes had the greatest impact on simulated maize and sorghum yields for all the counties. The next most critical input was rainfall, and then solar radiation for both maize and sorghum, especially for the dryland condition. For irrigated sorghum, solar radiation was the second most critical input instead of rainfall. The degree of sensitivity of yield to all variables for maize was larger than for sorghum except for solar radiation. Many models use a USDA curve number approach to represent soil water redistribution, so it will be important to have accurate curve numbers, rainfall, and soil depth to realistically simulate yields.

  17. Kriging atomic properties with a variable number of inputs

    Science.gov (United States)

    Davie, Stuart J.; Di Pasquale, Nicodemo; Popelier, Paul L. A.

    2016-09-01

    A new force field called FFLUX uses the machine learning technique kriging to capture the link between the properties (energies and multipole moments) of topological atoms (i.e., output) and the coordinates of the surrounding atoms (i.e., input). Here we present a novel, general method of applying kriging to chemical systems that do not possess a fixed number of (geometrical) inputs. Unlike traditional kriging methods, which require an input system to be of fixed dimensionality, the method presented here can be readily applied to molecular simulation, where an interaction cutoff radius is commonly used and the number of atoms or molecules within the cutoff radius is not constant. The method described here is general and can be applied to any machine learning technique that normally operates under a fixed number of inputs. In particular, the method described here is also useful for interpolating methods other than kriging, which may suffer from difficulties stemming from identical sets of inputs corresponding to different outputs or input biasing. As a demonstration, the new method is used to predict 54 energetic and electrostatic properties of the central water molecule of a set of 5000, 4 Å radius water clusters, with a variable number of water molecules. The results are validated against equivalent models from a set of clusters composed of a fixed number of water molecules (set to ten, i.e., decamers) and against models created by using a naïve method of treating the variable number of inputs problem presented. Results show that the 4 Å water cluster models, utilising the method presented here, return similar or better kriging models than the decamer clusters for all properties considered and perform much better than the truncated models.

  18. Bootstrap rank-ordered conditional mutual information (broCMI): A nonlinear input variable selection method for water resources modeling

    Science.gov (United States)

    Quilty, John; Adamowski, Jan; Khalil, Bahaa; Rathinasamy, Maheswaran

    2016-03-01

    The input variable selection problem has recently garnered much interest in the time series modeling community, especially within water resources applications, demonstrating that information theoretic (nonlinear)-based input variable selection algorithms such as partial mutual information (PMI) selection (PMIS) provide an improved representation of the modeled process when compared to linear alternatives such as partial correlation input selection (PCIS). PMIS is a popular algorithm for water resources modeling problems considering nonlinear input variable selection; however, this method requires the specification of two nonlinear regression models, each with parametric settings that greatly influence the selected input variables. Other attempts to develop input variable selection methods using conditional mutual information (CMI) (an analog to PMI) have been formulated under different parametric pretenses such as k nearest-neighbor (KNN) statistics or kernel density estimates (KDE). In this paper, we introduce a new input variable selection method based on CMI that uses a nonparametric multivariate continuous probability estimator based on Edgeworth approximations (EA). We improve the EA method by considering the uncertainty in the input variable selection procedure by introducing a bootstrap resampling procedure that uses rank statistics to order the selected input sets; we name our proposed method bootstrap rank-ordered CMI (broCMI). We demonstrate the superior performance of broCMI when compared to CMI-based alternatives (EA, KDE, and KNN), PMIS, and PCIS input variable selection algorithms on a set of seven synthetic test problems and a real-world urban water demand (UWD) forecasting experiment in Ottawa, Canada.

  19. Analysis of Input and Output of China’s Agriculture Based on Canonical Correlation

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    I select effective irrigated area, consumption of agricultural chemical fertilizer, electricity consumed in rural areas, and total power of agricultural machinery as input variables of China’s agriculture; I select grain, bean, tobacco, oil-bearing crop and fruit as output variables of China’s agriculture. By using the data of China Statistical Yearbook in 2010, based on the analysis method of canonical correlation, I conduct research on the input and output of China’s agriculture. The results show that consumption of chemical fertilizer has the biggest impact on the agricultural output of China, followed by the input of total power of agricultural machinery; the canonical variable of agricultural output of China is mainly impacted by grain, oil-bearing crop and fruit; in terms of the selected variables, the output increase of grain, oil-bearing crop and fruit in China arises from the input increase of agricultural chemical fertilizer and machinery, and there is high-degree correlation between the two. According to the conclusions, the policy suggestions are put forward as follows: gradually decrease consumption of chemical fertilizer; increase the use of modern agricultural machinery; increase agricultural irrigation input.

  20. How Much Input Is Enough? Correlating Comprehension and Child Language Input in an Endangered Language

    Science.gov (United States)

    Meakins, Felicity; Wigglesworth, Gillian

    2013-01-01

    In situations of language endangerment, the ability to understand a language tends to persevere longer than the ability to speak it. As a result, the possibility of language revival remains high even when few speakers remain. Nonetheless, this potential requires that those with high levels of comprehension received sufficient input as children for…

  1. Energy Inputs Uncertainty: Total Amount, Distribution and Correlation Between Different Forms of Energy

    Science.gov (United States)

    Deng, Yue

    2014-01-01

    Describes solar energy inputs contributing to ionospheric and thermospheric weather processes, including total energy amounts, distributions and the correlation between particle precipitation and Poynting flux.

  2. Generation of correlated finite alphabet waveforms using gaussian random variables

    KAUST Repository

    Ahmed, Sajid

    2016-01-13

    Various examples of methods and systems are provided for generation of correlated finite alphabet waveforms using Gaussian random variables in, e.g., radar and communication applications. In one example, a method includes mapping an input signal comprising Gaussian random variables (RVs) onto finite-alphabet non-constant-envelope (FANCE) symbols using a predetermined mapping function, and transmitting FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The FANCE waveforms can be based upon the mapping of the Gaussian RVs onto the FANCE symbols. In another example, a system includes a memory unit that can store a plurality of digital bit streams corresponding to FANCE symbols and a front end unit that can transmit FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The system can include a processing unit that can encode the input signal and/or determine the mapping function.

  3. Uncertainties Quantification and Propagation of Multiple Correlated Variables with Limited Samples

    Science.gov (United States)

    Zhanpeng, Shen; Xueqian, Chen; Xinen, Liu; Chaoping, Zang

    2016-09-01

    In order to estimate the reliability of an engineering structure based on limited test data, it is distinctly important to address both the epistemic uncertainty from lacking in samples and correlations between input uncertain variables. Both the probability boxes theory and copula function theory are utilized in proposed method to represent uncertainty and correlation of input variables respectively. Moreover, the uncertainty of response of interest is obtained by uncertainty propagation of correlated input variables. Nested sampling technique is adopted here to insure the propagation is always feasible and the response's uncertainty is characterized by a probability box. Finally, a numerical example illustrates the validity and effectiveness of our method. The results indicate that the epistemic uncertainty cannot be conveniently ignored when available samples are very limited and correlations among input variables may significantly affect the uncertainty of responses.

  4. Input variable selection for water resources systems using a modified minimum redundancy maximum relevance (mMRMR) algorithm

    Science.gov (United States)

    Hejazi, Mohamad I.; Cai, Ximing

    2009-04-01

    Input variable selection (IVS) is a necessary step in modeling water resources systems. Neglecting this step may lead to unnecessary model complexity and reduced model accuracy. In this paper, we apply the minimum redundancy maximum relevance (MRMR) algorithm to identifying the most relevant set of inputs in modeling a water resources system. We further introduce two modified versions of the MRMR algorithm ( α-MRMR and β-MRMR), where α and β are correction factors that are found to increase and decrease as a power-law function, respectively, with the progress of the input selection algorithms and the increase of the number of selected input variables. We apply the proposed algorithms to 22 reservoirs in California to predict daily releases based on a set from a 121 potential input variables. Results indicate that the two proposed algorithms are good measures of model inputs as reflected in enhanced model performance. The α-MRMR and β-MRMR values exhibit strong negative correlation to model performance as depicted in lower root-mean-square-error (RMSE) values.

  5. Antenna Correlation From Input Parameters for Arbitrary Topologies and Terminations

    DEFF Research Database (Denmark)

    Alrabadi, Osama; Andersen, Jørgen Bach; Pedersen, Gert Frølund

    2012-01-01

    The spatial correlation between pairs of antennas in a system comprised of N RF ports is found by extending the N × N scattering matrix to (N + 1)×(N + 1) spatial scattering matrix, where the extra space dimension accounts for the reference port patterns. The lossless property of the spatial scat...... scattering matrix in a 3D uniform field is employed for expressing the spatial correlation between the port patterns at arbitrary complex terminations merely from the reference scattering parameters and the complex terminations without any far-field calculation....

  6. Multimodal biometric fusion using multiple-input correlation filter classifiers

    Science.gov (United States)

    Hennings, Pablo; Savvides, Marios; Vijaya Kumar, B. V. K.

    2005-03-01

    In this work we apply a computationally efficient, closed form design of a jointly optimized filter bank of correlation filter classifiers for biometric verification with the use of multiple biometrics from individuals. Advanced correlation filters have been used successfully for biometric classification, and have shown robustness in verifying faces, palmprints and fingerprints. In this study we address the issues of performing robust biometric verification when multiple biometrics from the same person are available at the moment of authentication; we implement biometric fusion by using a filter bank of correlation filter classifiers which are jointly optimized with each biometric, instead of designing separate independent correlation filter classifiers for each biometric and then fuse the resulting match scores. We present results using fingerprint and palmprint images from a data set of 40 people, showing a considerable advantage in verification performance producing a large margin of separation between the impostor and authentic match scores. The method proposed in this paper is a robust and secure method for authenticating an individual.

  7. Speaker Input Variability Does Not Explain Why Larger Populations Have Simpler Languages.

    Directory of Open Access Journals (Sweden)

    Mark Atkinson

    Full Text Available A learner's linguistic input is more variable if it comes from a greater number of speakers. Higher speaker input variability has been shown to facilitate the acquisition of phonemic boundaries, since data drawn from multiple speakers provides more information about the distribution of phonemes in a speech community. It has also been proposed that speaker input variability may have a systematic influence on individual-level learning of morphology, which can in turn influence the group-level characteristics of a language. Languages spoken by larger groups of people have less complex morphology than those spoken in smaller communities. While a mechanism by which the number of speakers could have such an effect is yet to be convincingly identified, differences in speaker input variability, which is thought to be larger in larger groups, may provide an explanation. By hindering the acquisition, and hence faithful cross-generational transfer, of complex morphology, higher speaker input variability may result in structural simplification. We assess this claim in two experiments which investigate the effect of such variability on language learning, considering its influence on a learner's ability to segment a continuous speech stream and acquire a morphologically complex miniature language. We ultimately find no evidence to support the proposal that speaker input variability influences language learning and so cannot support the hypothesis that it explains how population size determines the structural properties of language.

  8. Researches on the Model of Telecommunication Service with Variable Input Tariff Rates

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The paper sets up and studies the model of the telecommunication queue servicing system with variable input tariff rates, which can relieve the crowding system traffic flows during the busy hour to enhance the utilizing rate of the telecom's resources.

  9. Structure Analysis of Typical Fuzzy Controllers with Unequally Spaced Fuzzy Sets for Input and Output Variables

    Institute of Scientific and Technical Information of China (English)

    FAN Xingzhe; ZHANG Naiyao; LINing

    2001-01-01

    In this paper, a kind of typical fuzzycontrollers is defined, which have two inputs (e and△c) and one output (△u); triangular, symmetric andfull-overlapped membership functions for input vari-ables; singleton and symmetric membership func-tions for output variable; linear fuzzy control rules;Sum-Product inference method, and weighted meanmethod for defuzzification. For this kind of typicalfuzzy controllers we have analyzed their analyticalstructure, limiting structure and local stability.

  10. Generation of correlated finite alphabet waveforms using gaussian random variables

    KAUST Repository

    Jardak, Seifallah

    2014-09-01

    Correlated waveforms have a number of applications in different fields, such as radar and communication. It is very easy to generate correlated waveforms using infinite alphabets, but for some of the applications, it is very challenging to use them in practice. Moreover, to generate infinite alphabet constant envelope correlated waveforms, the available research uses iterative algorithms, which are computationally very expensive. In this work, we propose simple novel methods to generate correlated waveforms using finite alphabet constant and non-constant-envelope symbols. To generate finite alphabet waveforms, the proposed method map the Gaussian random variables onto the phase-shift-keying, pulse-amplitude, and quadrature-amplitude modulation schemes. For such mapping, the probability-density-function of Gaussian random variables is divided into M regions, where M is the number of alphabets in the corresponding modulation scheme. By exploiting the mapping function, the relationship between the cross-correlation of Gaussian and finite alphabet symbols is derived. To generate equiprobable symbols, the area of each region is kept same. If the requirement is to have each symbol with its own unique probability, the proposed scheme allows us that as well. Although, the proposed scheme is general, the main focus of this paper is to generate finite alphabet waveforms for multiple-input multiple-output radar, where correlated waveforms are used to achieve desired beampatterns. © 2014 IEEE.

  11. Generating Correlated QPSK Waveforms By Exploiting Real Gaussian Random Variables

    KAUST Repository

    Jardak, Seifallah

    2012-11-01

    The design of waveforms with specified auto- and cross-correlation properties has a number of applications in multiple-input multiple-output (MIMO) radar, one of them is the desired transmit beampattern design. In this work, an algorithm is proposed to generate quadrature phase shift- keying (QPSK) waveforms with required cross-correlation properties using real Gaussian random-variables (RV’s). This work can be considered as the extension of what was presented in [1] to generate BPSK waveforms. This work will be extended for the generation of correlated higher-order phase shift-keying (PSK) and quadrature amplitude modulation (QAM) schemes that can better approximate the desired beampattern.

  12. LCA of emerging technologies: addressing high uncertainty on inputs' variability when performing global sensitivity analysis.

    Science.gov (United States)

    Lacirignola, Martino; Blanc, Philippe; Girard, Robin; Pérez-López, Paula; Blanc, Isabelle

    2017-02-01

    In the life cycle assessment (LCA) context, global sensitivity analysis (GSA) has been identified by several authors as a relevant practice to enhance the understanding of the model's structure and ensure reliability and credibility of the LCA results. GSA allows establishing a ranking among the input parameters, according to their influence on the variability of the output. Such feature is of high interest in particular when aiming at defining parameterized LCA models. When performing a GSA, the description of the variability of each input parameter may affect the results. This aspect is critical when studying new products or emerging technologies, where data regarding the model inputs are very uncertain and may cause misleading GSA outcomes, such as inappropriate input rankings. A systematic assessment of this sensitivity issue is now proposed. We develop a methodology to analyze the sensitivity of the GSA results (i.e. the stability of the ranking of the inputs) with respect to the description of such inputs of the model (i.e. the definition of their inherent variability). With this research, we aim at enriching the debate on the application of GSA to LCAs affected by high uncertainties. We illustrate its application with a case study, aiming at the elaboration of a simple model expressing the life cycle greenhouse gas emissions of enhanced geothermal systems (EGS) as a function of few key parameters. Our methodology allows identifying the key inputs of the LCA model, taking into account the uncertainty related to their description.

  13. Segmented correlation measurements on superconducting bandpass delta-sigma modulator with and without input tone

    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.

  14. Segmented correlation measurements on superconducting bandpass delta sigma modulator with and without input tone

    Science.gov (United States)

    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.

  15. Higher-order correlations in common input shapes the output spiking activity of a neural population

    Science.gov (United States)

    Montangie, Lisandro; Montani, Fernando

    2017-04-01

    Recent neurophysiological experiments suggest that populations of neurons use a computational scheme in which spike timing is regulated by common non-Gaussian inputs across neurons. The presence of beyond-pairwise correlations in the neuronal inputs and the spiking outputs following a non-Gaussian statistics elicits the need of developing a new theoretical framework taking into account the complexity of synchronous activity patterns. To this end, we quantify the amount of higher-order correlations in the common neuronal inputs and outputs of a population of neurons. We provide a novel formalism, of easy numerical implementation, that can capture the subtle changes of the inputs heterogeneities. Within our approach, correlations across neurons arise from q-Gaussian inputs into threshold neurons and higher-order correlations in the spiking outputs activity are quantified by the parameter q. We present an exhaustive analysis of how input statistics are transformed in this threshold process into output statistics, and we show under which conditions higher-order correlations can lead to either bigger or smaller number of synchronized spikes in the neural population outputs.

  16. Variable structure control for MRAC systems with perturbations in input and output channels

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A design scheme of variable structure model reference control systems using only input and output measurements is presented for the systems with unmodeled dynamics and disturbances in input and output channels. The modeled part of the systems has relative degree greater than one and unknown upper bound of degree. By introducing some auxiliary signals and normalized signals with memory functions and appropriate choice of controller parameters, the developed variable structure controller guarantees the global stability of the closed-loop system and the arbitrarily small tracking error.

  17. Graphical user interface for input output characterization of single variable and multivariable highly nonlinear systems

    Directory of Open Access Journals (Sweden)

    Shahrukh Adnan Khan M. D.

    2017-01-01

    Full Text Available This paper presents a Graphical User Interface (GUI software utility for the input/output characterization of single variable and multivariable nonlinear systems by obtaining the sinusoidal input describing function (SIDF of the plant. The software utility is developed on MATLAB R2011a environment. The developed GUI holds no restriction on the nonlinearity type, arrangement and system order; provided that output(s of the system is obtainable either though simulation or experiments. An insight to the GUI and its features are presented in this paper and example problems from both single variable and multivariable cases are demonstrated. The formulation of input/output behavior of the system is discussed and the nucleus of the MATLAB command underlying the user interface has been outlined. Some of the industries that would benefit from this software utility includes but not limited to aerospace, defense technology, robotics and automotive.

  18. Not All Children Agree: Acquisition of Agreement when the Input Is Variable

    Science.gov (United States)

    Miller, Karen

    2012-01-01

    In this paper we investigate the effect of variable input on the acquisition of grammar. More specifically, we examine the acquisition of the third person singular marker -s on the auxiliary "do" in comprehension and production in two groups of children who are exposed to similar varieties of English but that differ with respect to adult…

  19. Effects of uncertainty in major input variables on simulated functional soil behaviour

    NARCIS (Netherlands)

    Finke, P.A.; Wösten, J.H.M.; Jansen, M.J.W.

    1997-01-01

    Uncertainties in major input variables in water and solute models were quantified and their effects on simulated functional aspects of soil behaviour were studied using basic soil properties from an important soil map unit in the Netherlands. Two sources of uncertainty were studied: spatial

  20. Effects of uncertainty in major input variables on simulated functional soil behaviour

    NARCIS (Netherlands)

    Finke, P.A.; Wösten, J.H.M.; Jansen, M.J.W.

    1996-01-01

    Uncertainties in major input variables in water and solute models were quantified and their effects on simulated functional aspects of soil behaviour were studied using basic soil properties from an important soil map unit in the Netherlands. Two sources of uncertainty were studied: spatial

  1. Urban vs. Rural CLIL: An Analysis of Input-Related Variables, Motivation and Language Attainment

    Science.gov (United States)

    Alejo, Rafael; Piquer-Píriz, Ana

    2016-01-01

    The present article carries out an in-depth analysis of the differences in motivation, input-related variables and linguistic attainment of the students at two content and language integrated learning (CLIL) schools operating within the same institutional and educational context, the Spanish region of Extremadura, and differing only in terms of…

  2. Urban vs. Rural CLIL: An Analysis of Input-Related Variables, Motivation and Language Attainment

    Science.gov (United States)

    Alejo, Rafael; Piquer-Píriz, Ana

    2016-01-01

    The present article carries out an in-depth analysis of the differences in motivation, input-related variables and linguistic attainment of the students at two content and language integrated learning (CLIL) schools operating within the same institutional and educational context, the Spanish region of Extremadura, and differing only in terms of…

  3. A GENERAL APPROACH BASED ON AUTOCORRELATION TO DETERMINE INPUT VARIABLES OF NEURAL NETWORKS FOR TIME SERIES FORECASTING

    Institute of Scientific and Technical Information of China (English)

    HUANG Wei; NAKAMORI Yoshiteru; WANG Shouyang

    2004-01-01

    Input selection is probably one of the most critical decision issues in neural network designing, because it has a great impact on forecasting performance. Among the many applications of artificial neural networks to finance, time series forecasting is perhaps one of the most challenging issues. Considering the features of neural networks, we propose a general approach called Autocorrelation Criterion (AC) to determine the inputs variables for a neural network. The purpose is to seek optimal lag periods, which are more predictive and less correlated. AC is a data-driven approach in that there is no prior assumption about the models for time series under study. So it has extensive applications and avoids a lengthy experimentation and tinkering in input selection. We apply the approach to the determination of input variables for foreign exchange rate forecasting and conduct comparisons between AC and information-based in-sample model selection criterion. The experiment results show that AC outperforms information-based in-sample model selection criterion.

  4. A neuromorphic model of motor overflow in focal hand dystonia due to correlated sensory input

    Science.gov (United States)

    Sohn, Won Joon; Niu, Chuanxin M.; Sanger, Terence D.

    2016-10-01

    Objective. Motor overflow is a common and frustrating symptom of dystonia, manifested as unintentional muscle contraction that occurs during an intended voluntary movement. Although it is suspected that motor overflow is due to cortical disorganization in some types of dystonia (e.g. focal hand dystonia), it remains elusive which mechanisms could initiate and, more importantly, perpetuate motor overflow. We hypothesize that distinct motor elements have low risk of motor overflow if their sensory inputs remain statistically independent. But when provided with correlated sensory inputs, pre-existing crosstalk among sensory projections will grow under spike-timing-dependent-plasticity (STDP) and eventually produce irreversible motor overflow. Approach. We emulated a simplified neuromuscular system comprising two anatomically distinct digital muscles innervated by two layers of spiking neurons with STDP. The synaptic connections between layers included crosstalk connections. The input neurons received either independent or correlated sensory drive during 4 days of continuous excitation. The emulation is critically enabled and accelerated by our neuromorphic hardware created in previous work. Main results. When driven by correlated sensory inputs, the crosstalk synapses gained weight and produced prominent motor overflow; the growth of crosstalk synapses resulted in enlarged sensory representation reflecting cortical reorganization. The overflow failed to recede when the inputs resumed their original uncorrelated statistics. In the control group, no motor overflow was observed. Significance. Although our model is a highly simplified and limited representation of the human sensorimotor system, it allows us to explain how correlated sensory input to anatomically distinct muscles is by itself sufficient to cause persistent and irreversible motor overflow. Further studies are needed to locate the source of correlation in sensory input.

  5. Linear methods for input scenes restoration from signals of optical-digital pattern recognition correlator

    Science.gov (United States)

    Starikov, Sergey N.; Konnik, Mikhail V.; Manykin, Edward A.; Rodin, Vladislav G.

    2009-04-01

    Linear methods of restoration of input scene's images in optical-digital correlators are described. Relatively low signal to noise ratio of a camera's photo sensor and extensional PSF's size are special features of considered optical-digital correlator. RAW-files of real correlation signals obtained by digital photo sensor were used for input scene's images restoration. It is shown that modified evolution method, which employs regularization by Tikhonov, is better among linear deconvolution methods. As a regularization term, an inverse signal to noise ratio as a function of spatial frequencies was used. For additional improvement of restoration's quality, noise analysis of boundary areas of the image to be reconstructed was performed. Experimental results on digital restoration of input scene's images are presented.

  6. Identification of multiple inputs single output errors-in-variables system using cumulant

    Institute of Scientific and Technical Information of China (English)

    Haihui Long; Jiankang Zhao

    2014-01-01

    A higher-order cumulant-based weighted least square (HOCWLS) and a higher-order cumulant-based iterative least square (HOCILS) are derived for multiple inputs single output (MISO) errors-in-variables (EIV) systems from noisy input/output data. Whether the noises of the input/output of the system are white or colored, the proposed algorithms can be insensitive to these noises and yield unbiased estimates. To realize adaptive pa-rameter estimates, a higher-order cumulant-based recursive least square (HOCRLS) method is also studied. Convergence analy-sis of the HOCRLS is conducted by using the stochastic process theory and the stochastic martingale theory. It indicates that the parameter estimation error of HOCRLS consistently converges to zero under a generalized persistent excitation condition. The use-fulness of the proposed algorithms is assessed through numerical simulations.

  7. Input variable selection for data-driven models of Coriolis flowmeters for two-phase flow measurement

    Science.gov (United States)

    Wang, Lijuan; Yan, Yong; Wang, Xue; Wang, Tao

    2017-03-01

    Input variable selection is an essential step in the development of data-driven models for environmental, biological and industrial applications. Through input variable selection to eliminate the irrelevant or redundant variables, a suitable subset of variables is identified as the input of a model. Meanwhile, through input variable selection the complexity of the model structure is simplified and the computational efficiency is improved. This paper describes the procedures of the input variable selection for the data-driven models for the measurement of liquid mass flowrate and gas volume fraction under two-phase flow conditions using Coriolis flowmeters. Three advanced input variable selection methods, including partial mutual information (PMI), genetic algorithm-artificial neural network (GA-ANN) and tree-based iterative input selection (IIS) are applied in this study. Typical data-driven models incorporating support vector machine (SVM) are established individually based on the input candidates resulting from the selection methods. The validity of the selection outcomes is assessed through an output performance comparison of the SVM based data-driven models and sensitivity analysis. The validation and analysis results suggest that the input variables selected from the PMI algorithm provide more effective information for the models to measure liquid mass flowrate while the IIS algorithm provides a fewer but more effective variables for the models to predict gas volume fraction.

  8. Method and apparatus for smart battery charging including a plurality of controllers each monitoring input variables

    Science.gov (United States)

    Hammerstrom, Donald J.

    2013-10-15

    A method for managing the charging and discharging of batteries wherein at least one battery is connected to a battery charger, the battery charger is connected to a power supply. A plurality of controllers in communication with one and another are provided, each of the controllers monitoring a subset of input variables. A set of charging constraints may then generated for each controller as a function of the subset of input variables. A set of objectives for each controller may also be generated. A preferred charge rate for each controller is generated as a function of either the set of objectives, the charging constraints, or both, using an algorithm that accounts for each of the preferred charge rates for each of the controllers and/or that does not violate any of the charging constraints. A current flow between the battery and the battery charger is then provided at the actual charge rate.

  9. Wide Input Range Power Converters Using a Variable Turns Ratio Transformer

    DEFF Research Database (Denmark)

    Ouyang, Ziwei; Andersen, Michael A. E.

    2016-01-01

    A new integrated transformer with variable turns ratio is proposed to enable dc-dc converters operating over a wide input voltage range. The integrated transformer employs a new geometry of magnetic core with “four legs”, two primary windings with orthogonal arrangement, and “8” shape connection...... of diagonal secondary windings, in order to make the transformer turns ratio adjustable by controlling the phase between the two current excitations subjected to the two primary windings. Full-bridge boost dc-dc converter is employed with the proposed transformer to demonstrate the feasibility of the variable...

  10. Recurrent network models for perfect temporal integration of fluctuating correlated inputs.

    Directory of Open Access Journals (Sweden)

    Hiroshi Okamoto

    2009-06-01

    Full Text Available Temporal integration of input is essential to the accumulation of information in various cognitive and behavioral processes, and gradually increasing neuronal activity, typically occurring within a range of seconds, is considered to reflect such computation by the brain. Some psychological evidence suggests that temporal integration by the brain is nearly perfect, that is, the integration is non-leaky, and the output of a neural integrator is accurately proportional to the strength of input. Neural mechanisms of perfect temporal integration, however, remain largely unknown. Here, we propose a recurrent network model of cortical neurons that perfectly integrates partially correlated, irregular input spike trains. We demonstrate that the rate of this temporal integration changes proportionately to the probability of spike coincidences in synaptic inputs. We analytically prove that this highly accurate integration of synaptic inputs emerges from integration of the variance of the fluctuating synaptic inputs, when their mean component is kept constant. Highly irregular neuronal firing and spike coincidences are the major features of cortical activity, but they have been separately addressed so far. Our results suggest that the efficient protocol of information integration by cortical networks essentially requires both features and hence is heterotic.

  11. On how correlations between excitatory and inhibitory synaptic inputs maximize the information rate of neuronal firing

    Directory of Open Access Journals (Sweden)

    Pavel Anatolyevich Puzerey

    2014-06-01

    Full Text Available Cortical neurons receive barrages of excitatory and inhibitory inputs which are not independent, as network structure and synaptic kinetics impose statistical correlations. Experiments in vitro and in vivo have demonstrated correlations between inhibitory and excitatory synaptic inputs in which inhibition lags behind excitation in cortical neurons. This delay arises in feed-forward inhibition circuits and ensures that coincident excitation and inhibition do not preclude neuronal firing. Conversely, inhibition that is too delayed broadens neuronal integration times, thereby diminishing spike-time precision and increasing the firing frequency. This led us to hypothesize that the correlation between excitatory and inhibitory synaptic inputs modulates the encoding of information of neural spike trains. We tested this hypothesis by investigating the effect of such correlations on the information rate (IR of spike trains using the Hodgkin-Huxley model in which both synaptic and membrane conductances are stochastic. We investigated two different synaptic input regimes: balanced synaptic conductances and balanced currents. Our results show that correlations arising from the synaptic kinetics, tau, and millisecond lags, delta, of inhibition relative to excitation strongly affect the IR of spike trains. In the regime of balanced synaptic currents, for short time lags (delta ~ 1 ms there is an optimal tau that maximizes the IR of the postsynaptic spike train. Given the short time scales for monosynaptic inhibitory lags and synaptic decay kinetics reported in cortical neurons under physiological contexts, we propose that feed-forward inhibition in cortical circuits is poised to maximize the rate of information transfer between cortical neurons. Our results also provide a possible explanation for how certain drugs and genetic mutations affecting the synaptic kinetics can deteriorate information processing in the brain.

  12. Reliability Index of Caisson Breakwaters for Load Variables Correlated

    Institute of Scientific and Technical Information of China (English)

    郄禄文; 李炎保

    2004-01-01

    In order to suit the condition that the wave uplift is correlated with the horizontal wave load acting on a vertical breakwater, a generally used method for determining the reliability index β of the breakwater, i.e. the Hasofer-Lind method, is extended in a generalized stochastic space for correlative variables. The computational results for a caisson breakwater indicate that the value of β for the case of correlated variables is obviously smaller than that for the case of independent variables.

  13. A Model for Positively Correlated Count Variables

    DEFF Research Database (Denmark)

    Møller, Jesper; Rubak, Ege Holger

    2010-01-01

    An α-permanental random field is briefly speaking a model for a collection of non-negative integer valued random variables with positive associations. Though such models possess many appealing probabilistic properties, many statisticians seem unaware of α-permanental random fields and their poten......An α-permanental random field is briefly speaking a model for a collection of non-negative integer valued random variables with positive associations. Though such models possess many appealing probabilistic properties, many statisticians seem unaware of α-permanental random fields...

  14. Variable input observer for structural health monitoring of high-rate systems

    Science.gov (United States)

    Hong, Jonathan; Laflamme, Simon; Cao, Liang; Dodson, Jacob

    2017-02-01

    The development of high-rate structural health monitoring methods is intended to provide damage detection on timescales of 10 µs -10ms where speed of detection is critical to maintain structural integrity. Here, a novel Variable Input Observer (VIO) coupled with an adaptive observer is proposed as a potential solution for complex high-rate problems. The VIO is designed to adapt its input space based on real-time identification of the system's essential dynamics. By selecting appropriate time-delayed coordinates defined by both a time delay and an embedding dimension, the proper input space is chosen which allows more accurate estimations of the current state and a reduction of the convergence rate. The optimal time-delay is estimated based on mutual information, and the embedding dimension is based on false nearest neighbors. A simulation of the VIO is conducted on a two degree-of-freedom system with simulated damage. Results are compared with an adaptive Luenberger observer, a fixed time-delay observer, and a Kalman Filter. Under its preliminary design, the VIO converges significantly faster than the Luenberger and fixed observer. It performed similarly to the Kalman Filter in terms of convergence, but with greater accuracy.

  15. Quantum Encryption Protocol Based on Continuous Variable EPR Correlations

    Institute of Scientific and Technical Information of China (English)

    HE Guang-Qiang; ZENG Gui-Hua

    2006-01-01

    A quantum encryption protocol based on Gaussian-modulated continuous variable EPR correlations is proposed. The security is guaranteed by continuous variable EPR entanglement correlations produced by nondegenerate optical parametric amplifier (NOPA). For general beam splitter eavesdropping strategy, the mutual information Ⅰ(α, ε)between Alice and Eve is calculated by employing Shannon information theory. Finally the security analysis is presented.

  16. A Note on the Sum of Correlated Gamma Random Variables

    CERN Document Server

    Paris, Jose F

    2011-01-01

    The sum of correlated gamma random variables appears in the analysis of many wireless communications systems, e.g. in systems under Nakagami-m fading. In this Letter we obtain exact expressions for the probability density function (PDF) and the cumulative distribution function (CDF) of the sum of arbitrarily correlated gamma variables in terms of certain Lauricella functions.

  17. Correlation between discharge timings of pairs of motor units reveals the presence but not the proportion of common synaptic input to motor neurons.

    Science.gov (United States)

    Rodriguez-Falces, Javier; Negro, Francesco; Farina, Dario

    2017-01-18

    We investigated whether correlation measures derived from pairs of motor unit (MU) spike trains are reliable indicators of the degree of common synaptic input to motor neurons. Several 50-s isometric contractions of the biceps brachii muscle were performed at different target forces ranging from 10 to 30% of the maximal voluntary contraction (MVC) relying on force feedback. 48 pairs of MUs were examined at various force levels. Motor unit synchrony was assessed by cross-correlation analysis using three indices: the output correlation as the peak of the cross-histogram (ρ), the number of synchronous spikes per second (CIS), and per trigger (E). Individual analysis of MU pairs revealed that ρ, CIS, and E were most often positively associated to discharge rate (87, 85, and 76% of the MU pairs, respectively) and negatively to inter-spike interval variability (69, 65, and 62% of the MU pairs, respectively). Moreover, the behaviour of synchronization indices with discharge rate (and inter-spike interval variability) varied greatly among the MU pairs. These results were consistent with theoretical predictions, which showed that the output correlation between pairs of spike trains depends on the statistics of the input current and motor neuron intrinsic properties that differ for different motor neuron pairs. In conclusion, the synchronization between MU firing trains is necessarily caused by the (functional) common input to motor neurons, but it is not possible to infer the degree of shared common input to a pair of motor neurons based on correlation measures of their output spike trains.

  18. Interval arithmetic operations for uncertainty analysis with correlated interval variables

    Institute of Scientific and Technical Information of China (English)

    Chao Jiang; Chun-Ming Fu; Bing-Yu Ni; Xu Han

    2016-01-01

    A new interval arithmetic method is proposed to solve interval functions with correlated intervals through which the overestimation problem existing in interval analy-sis could be significantly alleviated. The correlation between interval parameters is defined by the multidimensional par-allelepiped model which is convenient to describe the correlative and independent interval variables in a unified framework. The original interval variables with correlation are transformed into the standard space without correlation, and then the relationship between the original variables and the standard interval variables is obtained. The expressions of four basic interval arithmetic operations, namely addi-tion, subtraction, multiplication, and division, are given in the standard space. Finally, several numerical examples and a two-step bar are used to demonstrate the effectiveness of the proposed method.

  19. Sliding window correlation analysis for dengue-climate variable relationship

    Science.gov (United States)

    Thiruchelvam, Loshini; Asirvadam, Vijanth S.; Dass, Sarat C.; Daud, Hanita; Gill, Balvinder S.

    2016-11-01

    This study discussed building of sliding windows to analyze the relationship between dengue incidences and weather variables of mean temperature, relative humidity and rainfall, across the timeline. A window sized of 20 was selected and applied to find correlation between dengue incidences and each of the weather variable. A few time lag of zero, two, four, six, and eight is compared and the time lag with best correlation is selected for each weather variable. Study did not found a good insight for analysis using mean temperature and relative humidity. For both these variables, it was suggested dengue incidences is better measured using fluctuation of maximum and minimum values. Analysis using rainfall variable was found to vary across the timeline in magnitude and direction of the correlation. Time lag of eight was found to be the most significant explaining the relationship between dengue incidences and rainfall variable.

  20. Simulation model structure numerically robust to changes in magnitude and combination of input and output variables

    DEFF Research Database (Denmark)

    Rasmussen, Bjarne D.; Jakobsen, Arne

    1999-01-01

    instabilities prevent the practical use of such a system model for more than one input/output combination and for other magnitudes of refrigerating capacities.A higher numerical robustness of system models can be achieved by making a model for the refrigeration cycle the core of the system model and by using...... variables with narrow definition intervals for the exchange of information between the cycle model and the component models.The advantages of the cycle-oriented method are illustrated by an example showing the refrigeration cycle similarities between two very different refrigeration systems.......Mathematical models of refrigeration systems are often based on a coupling of component models forming a “closed loop” type of system model. In these models the coupling structure of the component models represents the actual flow path of refrigerant in the system. Very often numerical...

  1. Exciton correlations and input-output relations in non-equilibrium exciton superfluids

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Jinwu, E-mail: jy306@ccs.msstate.edu [Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Department of Physics, Capital Normal University, Beijing 100048 (China); Department of Physics and Astronomy, Mississippi State University, MS 39762 (United States); Sun, Fadi; Yu, Yi-Xiang [Department of Physics and Astronomy, Mississippi State University, MS 39762 (United States); Institute of Physics, Chinese Academy of Sciences, Beijing, 100080 (China); Liu, Wuming [Institute of Physics, Chinese Academy of Sciences, Beijing, 100080 (China)

    2013-02-15

    The photoluminescence (PL) measurements on photons and the transport measurements on excitons are the two types of independent and complementary detection tools to search for possible exciton superfluids in electron-hole semi-conductor bilayer systems. In fact, it was believed that the transport measurements can provide more direct evidences on superfluids than the spectroscopic measurements. It is important to establish the relations between the two kinds of measurements. In this paper, using quantum Heisenberg-Langevin equations, we establish such a connection by calculating various exciton correlation functions in the putative exciton superfluids. These correlation functions include both normal and anomalous greater, lesser, advanced, retarded, and time-ordered exciton Green functions and also various two exciton correlation functions. We also evaluate the corresponding normal and anomalous spectral weights and the Keldysh distribution functions. We stress the violations of the fluctuation and dissipation theorem among these various exciton correlation functions in the non-equilibrium exciton superfluids. We also explore the input-output relations between various exciton correlation functions and those of emitted photons such as the angle resolved photon power spectrum, phase sensitive two mode squeezing spectrum and two photon correlations. Applications to possible superfluids in the exciton-polariton systems are also mentioned. For a comparison, using conventional imaginary time formalism, we also calculate all the exciton correlation functions in an equilibrium dissipative exciton superfluid in the electron-electron coupled semi-conductor bilayers at the quantum Hall regime at the total filling factor {nu}{sub T}=1. We stress the analogies and also important differences between the correlations functions in the two exciton superfluid systems. - Highlights: Black-Right-Pointing-Pointer Establish the relations between photoluminescence and transport

  2. Variable Correlation Digital Noise Source on FPGA — A Versatile Tool for Debugging Radio Telescope Backends

    Science.gov (United States)

    Buch, Kaushal D.; Gupta, Yashwant; Ajith Kumar, B.

    Contemporary wideband radio telescope backends are generally developed on Field Programmable Gate Arrays (FPGA) or hybrid (FPGA+GPU) platforms. One of the challenges faced while developing such instruments is the functional verification of the signal processing backend at various stages of development. In the case of an interferometer or pulsar backend, the typical requirement is for one independent noise source per input, with provision for a common, correlated signal component across all the inputs, with controllable level of correlation. This paper describes the design of a FPGA-based variable correlation Digital Noise Source (DNS), and its applications to built-in testing and debugging of correlators and beamformers. This DNS uses the Central Limit Theorem-based approach for generation of Gaussian noise, and the architecture is optimized for resource requirements and ease of integration with existing signal processing blocks on FPGA.

  3. Attitude Control Considering Variable Input Saturation Limit for a Spacecraft Equipped with Flywheels

    Institute of Scientific and Technical Information of China (English)

    TIAN Lin; XU Shijie

    2012-01-01

    A new attitude controller is proposed for spacecraft whose actuator has variable input saturation limit.There are three identical flywheels orthogonally mounted on board.Each rotor is driven by a brushless DC motor (BLDCM).Models of spacecraft attitude dynamics and flywheel rotor driving motor electromechanics are discussed in detail.The controller design is similar to saturation limit linear assignment.An auxiliary parameter and a boundary coefficient are imported into the controller to guarantee system stability and improve control performance.A time-varying and state-dependent flywheel output torque saturation limit model is established.Stability of the closed-loop control system and asymptotic convergence of system states are proved via Lyapunov methods and LaSalle invarianee principle.Boundedness of the auxiliary parameter ensures that the control objective can be achieved,while the boundary parameter's value makes a balance between system control performance and flywheel utilization efficiency.Compared with existing controllers,the newly developed controller with variable torque saturation limit can bring smoother control and faster system response.Numerical simulations validate the effectiveness of the controller.

  4. Grey Correlation Between Agricultural Input Factors and Regional GDP Growth in Anhui Province

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In order to analyze the relation between agricultural input factors and economic growth in Anhui Province,the evaluation index system of agricultural input is built from the perspectives of subject,object and tools based on grey system theory. The government investment in agricultural science and technology is selected as the index of labor subject,that is labor-related index(X1) ,the total sown area of crops is selected as the index of labor object(X2) ,the investment in rural water and electricity construction is chosen as the index of tools(X3) ,and the GDP of Anhui Province is denoted by X0. According to the relevant data,the improved model of grey correlation analysis is adopted to calculate the correlation among the investment in agricultural water and electricity construction,total sown area of crops,government investment in agricultural science and technology,and the GDP in Anhui Province during 2004-2008. Results show that investment in agricultural science and technology contribute the largest to GDP growth,the increase and change of the total sown area and the investment in rural water and electricity construction have a weak correlation with GDP,they are in a less consistent development trend. On this basis,the government of Anhui Province further proposes to increase the investment in agricultural science and technology,enhance the protection of arable lands,keep the total sown area of crops,and properly maintain the rural water and electricity construction.

  5. Quantum Correlations Relativity for Continuous-Variables Bipartite Systems

    CERN Document Server

    Dugic, M; Jeknic-Dugic, J

    2011-01-01

    Based on the so-called Entanglement Relativity, we point out relativity of the more general non-classical (quantum) correlations for the continuous-variables bipartite systems. Our observation points out that quantum processing resources based on the non-classical correlations (non-zero quantum discord) are ubiquitous in such systems.

  6. Quantum information tapping using a fiber optical parametric amplifier with noise figure improved by correlated inputs.

    Science.gov (United States)

    Guo, Xueshi; Li, Xiaoying; Liu, Nannan; Ou, Z Y

    2016-07-26

    One of the important functions in a communication network is the distribution of information. It is not a problem to accomplish this in a classical system since classical information can be copied at will. However, challenges arise in quantum system because extra quantum noise is often added when the information content of a quantum state is distributed to various users. Here, we experimentally demonstrate a quantum information tap by using a fiber optical parametric amplifier (FOPA) with correlated inputs, whose noise is reduced by the destructive quantum interference through quantum entanglement between the signal and the idler input fields. By measuring the noise figure of the FOPA and comparing with a regular FOPA, we observe an improvement of 0.7 ± 0.1 dB and 0.84 ± 0.09 dB from the signal and idler outputs, respectively. When the low noise FOPA functions as an information splitter, the device has a total information transfer coefficient of Ts+Ti = 1.5 ± 0.2, which is greater than the classical limit of 1. Moreover, this fiber based device works at the 1550 nm telecom band, so it is compatible with the current fiber-optical network for quantum information distribution.

  7. Quantum information tapping using a fiber optical parametric amplifier with noise figure improved by correlated inputs

    Science.gov (United States)

    Guo, Xueshi; Li, Xiaoying; Liu, Nannan; Ou, Z. Y.

    2016-07-01

    One of the important functions in a communication network is the distribution of information. It is not a problem to accomplish this in a classical system since classical information can be copied at will. However, challenges arise in quantum system because extra quantum noise is often added when the information content of a quantum state is distributed to various users. Here, we experimentally demonstrate a quantum information tap by using a fiber optical parametric amplifier (FOPA) with correlated inputs, whose noise is reduced by the destructive quantum interference through quantum entanglement between the signal and the idler input fields. By measuring the noise figure of the FOPA and comparing with a regular FOPA, we observe an improvement of 0.7 ± 0.1 dB and 0.84 ± 0.09 dB from the signal and idler outputs, respectively. When the low noise FOPA functions as an information splitter, the device has a total information transfer coefficient of Ts+Ti = 1.5 ± 0.2, which is greater than the classical limit of 1. Moreover, this fiber based device works at the 1550 nm telecom band, so it is compatible with the current fiber-optical network for quantum information distribution.

  8. Practical approximation method for firing-rate models of coupled neural networks with correlated inputs

    Science.gov (United States)

    Barreiro, Andrea K.; Ly, Cheng

    2017-08-01

    Rapid experimental advances now enable simultaneous electrophysiological recording of neural activity at single-cell resolution across large regions of the nervous system. Models of this neural network activity will necessarily increase in size and complexity, thus increasing the computational cost of simulating them and the challenge of analyzing them. Here we present a method to approximate the activity and firing statistics of a general firing rate network model (of the Wilson-Cowan type) subject to noisy correlated background inputs. The method requires solving a system of transcendental equations and is fast compared to Monte Carlo simulations of coupled stochastic differential equations. We implement the method with several examples of coupled neural networks and show that the results are quantitatively accurate even with moderate coupling strengths and an appreciable amount of heterogeneity in many parameters. This work should be useful for investigating how various neural attributes qualitatively affect the spiking statistics of coupled neural networks.

  9. Automated identification of neural correlates of continuous variables.

    Science.gov (United States)

    Daly, Ian; Hwang, Faustina; Kirke, Alexis; Malik, Asad; Weaver, James; Williams, Duncan; Miranda, Eduardo; Nasuto, Slawomir J

    2015-03-15

    The electroencephalogram (EEG) may be described by a large number of different feature types and automated feature selection methods are needed in order to reliably identify features which correlate with continuous independent variables. A method is presented for the automated identification of features that differentiate two or more groups in neurological datasets based upon a spectral decomposition of the feature set. Furthermore, the method is able to identify features that relate to continuous independent variables. The proposed method is first evaluated on synthetic EEG datasets and observed to reliably identify the correct features. The method is then applied to EEG recorded during a music listening task and is observed to automatically identify neural correlates of music tempo changes similar to neural correlates identified in a previous study. Finally, the method is applied to identify neural correlates of music-induced affective states. The identified neural correlates reside primarily over the frontal cortex and are consistent with widely reported neural correlates of emotions. The proposed method is compared to the state-of-the-art methods of canonical correlation analysis and common spatial patterns, in order to identify features differentiating synthetic event-related potentials of different amplitudes and is observed to exhibit greater performance as the number of unique groups in the dataset increases. The proposed method is able to identify neural correlates of continuous variables in EEG datasets and is shown to outperform canonical correlation analysis and common spatial patterns. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. A Study on the Fuzzy-Logic-Based Solar Power MPPT Algorithms Using Different Fuzzy Input Variables

    Directory of Open Access Journals (Sweden)

    Jaw-Kuen Shiau

    2015-04-01

    Full Text Available Maximum power point tracking (MPPT is one of the key functions of the solar power management system in solar energy deployment. This paper investigates the design of fuzzy-logic-based solar power MPPT algorithms using different fuzzy input variables. Six fuzzy MPPT algorithms, based on different input variables, were considered in this study, namely (i slope (of solar power-versus-solar voltage and changes of the slope; (ii slope and variation of the power; (iii variation of power and variation of voltage; (iv variation of power and variation of current; (v sum of conductance and increment of the conductance; and (vi sum of angles of arctangent of the conductance and arctangent of increment of the conductance. Algorithms (i–(iv have two input variables each while algorithms (v and (vi use a single input variable. The fuzzy logic MPPT function is deployed using a buck-boost power converter. This paper presents the details of the determinations, considerations of the fuzzy rules, as well as advantages and disadvantages of each MPPT algorithm based upon photovoltaic (PV cell properties. The range of the input variable of Algorithm (vi is finite and the maximum power point condition is well defined in steady condition and, therefore, it can be used for multipurpose controller design. Computer simulations are conducted to verify the design.

  11. Effect of variable heat input on the heat transfer characteristics in an Organic Rankine Cycle system

    Directory of Open Access Journals (Sweden)

    Aboaltabooq Mahdi Hatf Kadhum

    2016-01-01

    Full Text Available This paper analyzes the heat transfer characteristics of an ORC evaporator applied on a diesel engine using measured data from experimental work such as flue gas mass flow rate and flue gas temperature. A mathematical model was developed with regard to the preheater, boiler and the superheater zones of a counter flow evaporator. Each of these zones has been subdivided into a number of cells. The hot source of the ORC cycle was modeled. The study involves the variable heat input's dependence on the ORC system's heat transfer characteristics, with especial emphasis on the evaporator. The results show that the refrigerant's heat transfer coefficient has a higher value for a 100% load from the diesel engine, and decreases with the load decrease. Also, on the exhaust gas side, the heat transfer coefficient decreases with the decrease of the load. The refrigerant's heat transfer coefficient increased normally with the evaporator's tube length in the preheater zone, and then increases rapidly in the boiler zone, followed by a decrease in the superheater zone. The exhaust gases’ heat transfer coefficient increased with the evaporator’ tube length in all zones. The results were compared with result by other authors and were found to be in agreement.

  12. Effect of variable heat input on the heat transfer characteristics in an Organic Rankine Cycle system

    Directory of Open Access Journals (Sweden)

    Aboaltabooq Mahdi Hatf Kadhum

    2016-01-01

    Full Text Available This paper analyzes the heat transfer characteristics of an ORC evaporator applied on a diesel engine using measured data from experimental work such as flue gas mass flow rate and flue gas temperature. A mathematical model was developed with regard to the preheater, boiler and the superheater zones of a counter flow evaporator. Each of these zones has been subdivided into a number of cells. The hot source of the ORC cycle was modeled. The study involves the variable heat input's dependence on the ORC system's heat transfer characteristics, with especial emphasis on the evaporator. The results show that the refrigerant's heat transfer coefficient has a higher value for a 100% load from the diesel engine, and decreases with the load decrease. Also, on the exhaust gas side, the heat transfer coefficient decreases with the decrease of the load. The refrigerant's heat transfer coefficient increased normally with the evaporator's tube length in the preheater zone, and then increases rapidly in the boiler zone, followed by a decrease in the superheater zone. The exhaust gases’ heat transfer coefficient increased with the evaporator’ tube length in all zones. The results were compared with result by other authors and were found to be in agreement.

  13. Extension of latin hypercube samples with correlated variables.

    Energy Technology Data Exchange (ETDEWEB)

    Hora, Stephen Curtis (University of Hawaii at Hilo, HI); Helton, Jon Craig (Arizona State University, Tempe, AZ); Sallaberry, Cedric J. PhD. (.; .)

    2006-11-01

    A procedure for extending the size of a Latin hypercube sample (LHS) with rank correlated variables is described and illustrated. The extension procedure starts with an LHS of size m and associated rank correlation matrix C and constructs a new LHS of size 2m that contains the elements of the original LHS and has a rank correlation matrix that is close to the original rank correlation matrix C. The procedure is intended for use in conjunction with uncertainty and sensitivity analysis of computationally demanding models in which it is important to make efficient use of a necessarily limited number of model evaluations.

  14. Untangling complex dynamical systems via derivative-variable correlations

    Science.gov (United States)

    Levnaji, Zoran; Pikovsky, Arkady

    2014-05-01

    Inferring the internal interaction patterns of a complex dynamical system is a challenging problem. Traditional methods often rely on examining the correlations among the dynamical units. However, in systems such as transcription networks, one unit's variable is also correlated with the rate of change of another unit's variable. Inspired by this, we introduce the concept of derivative-variable correlation, and use it to design a new method of reconstructing complex systems (networks) from dynamical time series. Using a tunable observable as a parameter, the reconstruction of any system with known interaction functions is formulated via a simple matrix equation. We suggest a procedure aimed at optimizing the reconstruction from the time series of length comparable to the characteristic dynamical time scale. Our method also provides a reliable precision estimate. We illustrate the method's implementation via elementary dynamical models, and demonstrate its robustness to both model error and observation error.

  15. Correlations between Optical Variability and Physical Parameters of Quasars

    Indian Academy of Sciences (India)

    Wenwen Zuo; Xue-Bing Wu; Yi-Qing Liu; Cheng-Liang Jiao

    2014-09-01

    Optical variability is an important feature of quasars. Taking advantage of a larger sample of 7658 quasars from SDSS Stripe 82 and relatively more photometric data points for each quasar, we estimate their variability amplitudes and divide the sample into small bins of various parameters. An anticorrelation between variability amplitude and rest-frame wavelength is found. Variability increases as either luminosity or Eddington ratio decreases. The relationship between variability and black hole mass is uncertain. The intrinsic distribution of variability amplitudes for radio-loud and radio-quiet quasars are different. Both radio-loud and radio-quiet quasars exhibit a bluer-when-brighter chromatism. With the Shakura–Sunyaev disk model, we find that changes of accretion rate play an important role in producing the observed optical variability. However, the predicted positive correlation between variability and black hole mass seems to be inconsistent with the observed negative correlation between them in small bins of Eddington ratio, which suggests that other physical mechanisms may still need to be considered in modifying the simple accretion disk model. The different mechanisms in radio-loud and radio-quiet quasars are discussed.

  16. Behavioral and Electrophysiological Evidence for Early and Automatic Detection of Phonological Equivalence in Variable Speech Inputs

    Science.gov (United States)

    Kharlamov, Viktor; Campbell, Kenneth; Kazanina, Nina

    2011-01-01

    Speech sounds are not always perceived in accordance with their acoustic-phonetic content. For example, an early and automatic process of perceptual repair, which ensures conformity of speech inputs to the listener's native language phonology, applies to individual input segments that do not exist in the native inventory or to sound sequences that…

  17. Correlational study of psychological variables self-confidence and anxiety

    Directory of Open Access Journals (Sweden)

    Gloria González Campos

    2015-12-01

    Full Text Available Abstract The purpose of this study is to analyze the concurrent validity of the psychological variables self-confidence and anxiety among the psychological measurement instruments: Psychological Characteristics Questionnaire related to Sports Performance (CPRD; Competitive State Anxiety Inventory-2 (CSAI-2; and Sports Psychological Inventory LOEHR. For this purpose, a correlational study was conducted between the selected variables and pertinent aspects of the measurement instruments. The study has revealed that the psychological variables self-confidence and anxiety are relevant in all three instruments, although not in all of the selected items.

  18. Modeling the BOD of Danube River in Serbia using spatial, temporal, and input variables optimized artificial neural network models.

    Science.gov (United States)

    Šiljić Tomić, Aleksandra N; Antanasijević, Davor Z; Ristić, Mirjana Đ; Perić-Grujić, Aleksandra A; Pocajt, Viktor V

    2016-05-01

    This paper describes the application of artificial neural network models for the prediction of biological oxygen demand (BOD) levels in the Danube River. Eighteen regularly monitored water quality parameters at 17 stations on the river stretch passing through Serbia were used as input variables. The optimization of the model was performed in three consecutive steps: firstly, the spatial influence of a monitoring station was examined; secondly, the monitoring period necessary to reach satisfactory performance was determined; and lastly, correlation analysis was applied to evaluate the relationship among water quality parameters. Root-mean-square error (RMSE) was used to evaluate model performance in the first two steps, whereas in the last step, multiple statistical indicators of performance were utilized. As a result, two optimized models were developed, a general regression neural network model (labeled GRNN-1) that covers the monitoring stations from the Danube inflow to the city of Novi Sad and a GRNN model (labeled GRNN-2) that covers the stations from the city of Novi Sad to the border with Romania. Both models demonstrated good agreement between the predicted and actually observed BOD values.

  19. Comparison Study on Empirical Correlation for Mass Transfer Coefficient with Gas Hold-up and Input Power of Aeration Process

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang Kyoo; Yang, Hei Cheon [Chonnam Nat’l Univ., Gwangju (Korea, Republic of)

    2017-06-15

    As stricter environmental regulation have led to an increase in the water treatment cost, it is necessary to quantitatively study the input power of the aeration process to improve the energy efficiency of the water treatment processes. The objective of this study is to propose the empirical correlations for the mass transfer coefficient with the gas hold-up and input power in order to investigate the mass transfer characteristics of the aeration process. It was found that as the input power increases, the mass transfer coefficient increases because of the decrease of gas hold-up and increase of Reynolds number, the penetration length, and dispersion of mixed flow. The correlations for the volumetric mass transfer coefficients with gas hold-up and input power were consistent with the experimental data, with the maximum deviation less than approximately ±10.0%.

  20. Spatiotemporal Correlations between Water Footprint and Agricultural Inputs: A Case Study of Maize Production in Northeast China

    Directory of Open Access Journals (Sweden)

    Peili Duan

    2015-07-01

    Full Text Available To effectively manage water resources in agricultural production, it is necessary to understand the spatiotemporal variation of the water footprint (WF and the influences of agricultural inputs. Employing spatial autocorrelation analysis and a geographically weighted regression (GWR model, we explored the spatial variations of the WF and their relationships with agricultural inputs from 1998 to 2012 in Northeast China. The results indicated that: (1 the spatial distribution of WFs for the 36 major maize production prefectures was heterogeneous in Northeast China; (2 a cluster of high WFs was found in southeast Liaoning Province, while a cluster of low WFs was found in central Jilin Province, and (3 spatial and temporal differentiation in the correlations between the WF of maize production and agricultural inputs existed according to the GWR model. These correlations increased over time. Our results suggested that localized strategies for reducing the WF should be formulated based on specific relationships between the WF and agricultural inputs.

  1. An inequality for correlations in unidimensional monotone latent variable models for binary variables.

    Science.gov (United States)

    Ellis, Jules L

    2014-04-01

    It is shown that a unidimensional monotone latent variable model for binary items implies a restriction on the relative sizes of item correlations: The negative logarithm of the correlations satisfies the triangle inequality. This inequality is not implied by the condition that the correlations are nonnegative, the criterion that coefficient H exceeds 0.30, or manifest monotonicity. The inequality implies both a lower bound and an upper bound for each correlation between two items, based on the correlations of those two items with every possible third item. It is discussed how this can be used in Mokken's (A theory and procedure of scale-analysis, Mouton, The Hague, 1971) scale analysis.

  2. Testing Dependent Correlations with Nonoverlapping Variables: A Monte Carlo Simulation

    Science.gov (United States)

    Silver, N. Clayton; Hittner, James B.; May, Kim

    2004-01-01

    The authors conducted a Monte Carlo simulation of 4 test statistics or comparing dependent correlations with no variables in common. Empirical Type 1 error rates and power estimates were determined for K. Pearson and L. N. G. Filon's (1898) z, O. J. Dunn and V. A. Clark's (1969) z, J. H. Steiger's (1980) original modification of Dunn and Clark's…

  3. Sediment records of highly variable mercury inputs to mountain lakes in Patagonia during the past millennium

    Science.gov (United States)

    Ribeiro Guevara, S.; Meili, M.; Rizzo, A.; Daga, R.; Arribére, M.

    2010-04-01

    High Hg levels in the pristine lacustrine ecosystems of the Nahuel Huapi National Park, a protected zone situated in the Andes of Northern Patagonia, Argentina, have initiated further investigations on Hg cycling and source identification. Here we report Hg records in sedimentary sequences to identify atmospheric sources during the past millennium. In addition to global transport and deposition, a potential atmospheric Hg source to be considered is the local emissions associated with volcanic activity, because the Park is situated in the Southern Volcanic Zone. Two sediment cores were extracted from Lake Tonček, a small, high-altitude system reflecting mainly direct inputs associated with atmospheric contributions, and Lake Moreno Oeste, a much larger and deeper lake having an extended watershed covered mostly by native forest. The sedimentary sequences were dated based on both 210Pb and 137Cs profiles. In addition, tephra layers were identified and geochemically characterized for chronological application and to investigate any association of volcanic eruptions with Hg records. Hg concentrations in sediments were measured along with 32 other elements, as well as organic matter, subfossil chironomids, and biogenic silica. Observed background Hg concentrations, determined from the sequence domains with lower values, ranged from 50 to 100 ng g-1 dry weight (DW), whereas the surficial layers reached 200 to 500 ng g-1 DW. In addition to this traditional pattern, however, two deep domains in both sequences showed dramatically increased Hg levels reaching 400 to 650 ng g-1 DW; the upper dated to the 18th to 19th centuries, and the lower around the 13th century. These concentrations are not only elevated in the present profiles but also many-fold above the background values determined in other fresh water sediments, as were also the Hg fluxes, reaching 120 to 150 μg m-2 y-1 in Lake Tonček . No correlation was observed between Hg concentrations and the contents of

  4. Scalable time-correlated photon counting system with multiple independent input channels.

    Science.gov (United States)

    Wahl, Michael; Rahn, Hans-Jürgen; Röhlicke, Tino; Kell, Gerald; Nettels, Daniel; Hillger, Frank; Schuler, Ben; Erdmann, Rainer

    2008-12-01

    Time-correlated single photon counting continues to gain importance in a wide range of applications. Most prominently, it is used for time-resolved fluorescence measurements with sensitivity down to the single molecule level. While the primary goal of the method used to be the determination of fluorescence lifetimes upon optical excitation by short light pulses, recent modifications and refinements of instrumentation and methodology allow for the recovery of much more information from the detected photons, and enable entirely new applications. This is achieved most successfully by continuously recording individually detected photons with their arrival time and detection channel information (time tagging), thus avoiding premature data reduction and concomitant loss of information. An important property of the instrumentation used is the number of detection channels and the way they interrelate. Here we present a new instrument architecture that allows scalability in terms of the number of input channels while all channels are synchronized to picoseconds of relative timing and yet operate independent of each other. This is achieved by means of a modular design with independent crystal-locked time digitizers and a central processing unit for sorting and processing of the timing data. The modules communicate through high speed serial links supporting the full throughput rate of the time digitizers. Event processing is implemented in programmable logic, permitting classical histogramming, as well as time tagging of individual photons and their temporally ordered streaming to the host computer. Based on the time-ordered event data, any algorithms and methods for the analysis of fluorescence dynamics can be implemented not only in postprocessing but also in real time. Results from recently emerging single molecule applications are presented to demonstrate the capabilities of the instrument.

  5. Auditory nerve inputs to cochlear nucleus neurons studied with cross-correlation.

    Science.gov (United States)

    Young, E D; Sachs, M B

    2008-06-12

    The strength of synapses between auditory nerve (AN) fibers and ventral cochlear nucleus (VCN) neurons is an important factor in determining the nature of neural integration in VCN neurons of different response types. Synaptic strength was analyzed using cross-correlation of spike trains recorded simultaneously from an AN fiber and a VCN neuron in anesthetized cats. VCN neurons were classified as chopper, primarylike, and onset using previously defined criteria, although onset neurons usually were not analyzed because of their low discharge rates. The correlograms showed an excitatory peak (EP), consistent with monosynaptic excitation, in AN-VCN pairs with similar best frequencies (49% 24/49 of pairs with best frequencies within +/-5%). Chopper and primarylike neurons showed similar EPs, except that the primarylike neurons had shorter latencies and shorter-duration EPs. Large EPs consistent with end bulb terminals on spherical bushy cells were not observed, probably because of the low probability of recording from one. The small EPs observed in primarylike neurons, presumably spherical bushy cells, could be derived from small terminals that accompany end bulbs on these cells. EPs on chopper or primarylike-with-notch neurons were consistent with the smaller synaptic terminals on multipolar and globular bushy cells. Unexpectedly, EPs were observed only at sound levels within about 20 dB of threshold, showing that VCN responses to steady tones shift from a 1:1 relationship between AN and VCN spikes at low sound levels to a more autonomous mode of firing at high levels. In the high level mode, the pattern of output spikes seems to be determined by the properties of the postsynaptic spike generator rather than the input spike patterns. The EP amplitudes did not change significantly when the presynaptic spike was preceded by either a short or long interspike interval, suggesting that synaptic depression and facilitation have little effect under the conditions studied

  6. Effects of reconstruction filter and input parameter variability on object detectability in CT imaging

    Science.gov (United States)

    Boedeker, Kirsten L.

    The purpose of this work is to investigate and quantify the effects of technical parameter variability and reconstruction algorithm on image quality and object detectability. To accomplish this, metrics of both noise and signal to noise ratio (SNR) are explored and then applied in object detection tasks using a computer aided diagnosis (CAD) system. The noise power spectrum (NPS) is investigated as a noise metric in that it describes both the magnitude of noise and the spatial characteristics of noise that are introduced by the reconstruction algorithm. The NPS was found to be much more robust than the conventional standard deviation metric. The noise equivalent quanta (NEQ) is also studied as a tool for comparing effects of acquisition parameters (esp. mAs) on noise and, as NEQ is not influenced by reconstruction filter or other post-processing, its utility for comparison across different techniques and manufacturers is demonstrated. The Ideal Bayesian Observer (IBO) and Non-Prewhitening Matched Filter (NPWMF) are investigated as SNR metrics under a variety of acquisition and reconstruction conditions. The signal and noise processes of image formation were studied individually, which allowed for analysis of their separate effects on the overall SNR. The SNR metrics were found to characterize the influence of reconstruction filter and technical parameter variability with high sensitivity. To correlate the above SNR metrics with detection, signal images were combined with noise images and passed to a CAD system. A simulated lung nodule detection task was performed on a series of objects of increasing contrast. The average minimum contrast detected and corresponding IBO and NPWMF SNR values were recorded over 100 trials for each reconstruction filter and technical parameter condition studied. Among the trends discovered, it was found that detectability scales with SNR as mAs is varied. Furthermore, the CAD system appears to under-perform when sharp algorithms are

  7. Automated identification of neural correlates of continuous variables.

    OpenAIRE

    Daly, I; Hwang, F.; Kirke, A.; Malik, A.; Weaver, J.; Williams, D; Miranda, E; Nasuto, SJ

    2015-01-01

    BACKGROUND: The electroencephalogram (EEG) may be described by a large number of different feature types and automated feature selection methods are needed in order to reliably identify features which correlate with continuous independent variables. NEW METHOD: A method is presented for the automated identification of features that differentiate two or more groups in neurological datasets based upon a spectral decomposition of the feature set. Furthermore, the method is able to identify featu...

  8. GENETIC VARIABILITY AND CORRELATION STUDIES IN BRINJAL (SOLANUM MELONGENA L.)

    OpenAIRE

    Bhukya Ravi Nayak; P. K. Nagre

    2013-01-01

    The present investigation was conducted at Department of Horticulture, Horticulture Garden, Dr. PDKV, Akola (M.S.), during kharif 2012-13. The experimental material comprised of 20 genotypes along with one check of brinjal and the experimental was laid out in randomized block design with three replications. Variability studies revealed that highly significant differences were recorded among the varieties for all characters. Correlation and path analysis revealed that fruit length, diameter, w...

  9. Assessment of input uncertainty by seasonally categorized latent variables using SWAT

    Science.gov (United States)

    Watershed processes have been explored with sophisticated simulation models for the past few decades. It has been stated that uncertainty attributed to alternative sources such as model parameters, forcing inputs, and measured data should be incorporated during the simulation process. Among varyin...

  10. Perils of correlating CUSUM-transformed variables to infer ecological relationships (Breton et al. 2006; Glibert 2010)

    Science.gov (United States)

    Cloern, James E.; Jassby, Alan D.; Carstensen, Jacob; Bennett, William A.; Kimmerer, Wim; Mac Nally, Ralph; Schoellhamer, David H.; Winder, Monika

    2012-01-01

    We comment on a nonstandard statistical treatment of time-series data first published by Breton et al. (2006) in Limnology and Oceanography and, more recently, used by Glibert (2010) in Reviews in Fisheries Science. In both papers, the authors make strong inferences about the underlying causes of population variability based on correlations between cumulative sum (CUSUM) transformations of organism abundances and environmental variables. Breton et al. (2006) reported correlations between CUSUM-transformed values of diatom biomass in Belgian coastal waters and the North Atlantic Oscillation, and between meteorological and hydrological variables. Each correlation of CUSUM-transformed variables was judged to be statistically significant. On the basis of these correlations, Breton et al. (2006) developed "the first evidence of synergy between climate and human-induced river-based nitrate inputs with respect to their effects on the magnitude of spring Phaeocystis colony blooms and their dominance over diatoms."

  11. Neural Network Based Scheduling for Variable-Length Packets in Gigabit Router with Crossbar Switch Fabric and Input Queuing

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A high-speed and effective packet scheduling method is crucial to the performance of Gigabit routers. The paper studies the variable-length packet scheduling problem in Gigabit router with crossbar switch fabric and input queuing, and a scheduling method based on neural network is proposed. For the proposed method, a scheduling system structure fit for the variable-length packet case is presented first, then some rules for scheduling are given, At last, an optimal scheduling method using Hopfield neural network is proposed based on the rules. Furthermore, the paper discusses that the proposed method can be realized by hardware circuit. The simulation result shows the effectiveness of the proposed method.

  12. Balance 1 year after TKA: correlation with clinical variables.

    Science.gov (United States)

    Bascuas, Iria; Tejero, Marta; Monleón, Sandra; Boza, Roser; Muniesa, Josep Maria; Belmonte, Roser

    2013-01-01

    Knee osteoarthritis results in changes that affect balance. It has been reported that osteoarthritis worsens proprioception and increases the risk of falling. The objective of this study was to assess changes in balance among patients with knee osteoarthritis at 1 year after total knee arthroplasty (TKA) surgery and its relationship with clinical variables. This prospective, observational study evaluated 44 patients before and 1 year after TKA. Variables analyzed included age, body mass index, pain, range of motion for both knees, bilateral quadriceps and hamstrings muscle strength, gait velocity, and Knee Society score. Balance and posture control were assessed using the following computerized posturography tests: the weight bearing test, modified Clinical Test of Sensory Interaction on Balance (mCTSIB) test, and sit-to-stand test. Pre- and postoperative differences were analyzed using Wilcoxon and chi-square tests, and effect size was measured using standardized response mean. Correlations were assessed by the Spearman test. One year after TKA, some improvement in balance tests was observed. Significant differences were observed in the mCTSIB test: foam surface with open eyes (P≤.001), foam surface with closed eyes (P≤.001), and composite value (P≤.001). Effect size was moderate to high. Age showed significant correlation with mCTSIB composite value changes (-0.369; P=.037). No significant correlations were found between posturographic tests and other analyzed variables. Balance measured by computerized posturography improved 1 year after TKA. Significant changes were observed between open and closed eyes using a foam surface for the mCTSIB test. A mild negative correlation was found between age and posturographic changes.

  13. A radiobiological model of radiotherapy response and its correlation with prognostic imaging variables

    Science.gov (United States)

    Crispin-Ortuzar, Mireia; Jeong, Jeho; Fontanella, Andrew N.; Deasy, Joseph O.

    2017-04-01

    Radiobiological models of tumour control probability (TCP) can be personalized using imaging data. We propose an extension to a voxel-level radiobiological TCP model in order to describe patient-specific differences and intra-tumour heterogeneity. In the proposed model, tumour shrinkage is described by means of a novel kinetic Monte Carlo method for inter-voxel cell migration and tumour deformation. The model captures the spatiotemporal evolution of the tumour at the voxel level, and is designed to take imaging data as input. To test the performance of the model, three image-derived variables found to be predictive of outcome in the literature have been identified and calculated using the model’s own parameters. Simulating multiple tumours with different initial conditions makes it possible to perform an in silico study of the correlation of these variables with the dose for 50% tumour control (\\text{TC}{{\\text{D}}50} ) calculated by the model. We find that the three simulated variables correlate with the calculated \\text{TC}{{\\text{D}}50} . In addition, we find that different variables have different levels of sensitivity to the spatial distribution of hypoxia within the tumour, as well as to the dynamics of the migration mechanism. Finally, based on our results, we observe that an adequate combination of the variables may potentially result in higher predictive power.

  14. Method of Removing the Cross-correlation Noise for Dual-input and Dual-output SAR

    Directory of Open Access Journals (Sweden)

    Huang Ping-ping

    2012-03-01

    Full Text Available According to analysis of separating the mixed echo by suppressing the cross-correlation noise in dual-input and dual-output SAR system, a new method based on threshold filter and inverse filter was proposed. The method can eliminate the most energy of cross-correlation noise by threshold filter, which can suppress the cross-correlation noise well. The principle and implementation steps are presented in detail. The computer simulation and account for the integrated sidelobe ratio showed the effectiveness of the proposed method.

  15. Why does parental language input style predict child language development? A twin study of gene–environment correlation

    Science.gov (United States)

    Dale, Philip S.; Tosto, Maria Grazia; Hayiou-Thomas, Marianna E.; Plomin, Robert

    2015-01-01

    There are well-established correlations between parental input style and child language development, which have typically been interpreted as evidence that the input style causes, or influences the rate of, changes in child language. We present evidence from a large twin study (TEDS; 8395 pairs for this report) that there are also likely to be both child-to-parent effects and shared genetic effects on parent and child. Self-reported parental language style at child age 3 and age 4 was aggregated into an ‘informal language stimulation’ factor and a ‘corrective feedback’ factor at each age; the former was positively correlated with child language concurrently and longitudinally at 3, 4, and 4.5 years, whereas the latter was weakly and negatively correlated. Both parental input factors were moderately heritable, as was child language. Longitudinal bivariate analysis showed that the correlation between the language stimulation factor and child language was significantly and moderately due to shared genes. There is some suggestive evidence from longitudinal phenotypic analysis that the prediction from parental language stimulation to child language includes both evocative and passive gene–environment correlation, with the latter playing a larger role. Learning outcomes: The reader will understand why correlations between parental language and rate of child language are by themselves ambiguous, and how twin studies can clarify the relationship. The reader will also understand that, based on the present study, at least two aspects of parental language style – informal language stimulation and corrective feedback – have substantial genetic influence, and that for informal language stimulation, a substantial portion of the prediction to child language represents the effect of shared genes on both parent and child. It will also be appreciated that these basic research findings do not imply that parental language input style is unimportant or that interventions

  16. Why does parental language input style predict child language development? A twin study of gene-environment correlation.

    Science.gov (United States)

    Dale, Philip S; Tosto, Maria Grazia; Hayiou-Thomas, Marianna E; Plomin, Robert

    2015-01-01

    There are well-established correlations between parental input style and child language development, which have typically been interpreted as evidence that the input style causes, or influences the rate of, changes in child language. We present evidence from a large twin study (TEDS; 8395 pairs for this report) that there are also likely to be both child-to-parent effects and shared genetic effects on parent and child. Self-reported parental language style at child age 3 and age 4 was aggregated into an 'informal language stimulation' factor and a 'corrective feedback' factor at each age; the former was positively correlated with child language concurrently and longitudinally at 3, 4, and 4.5 years, whereas the latter was weakly and negatively correlated. Both parental input factors were moderately heritable, as was child language. Longitudinal bivariate analysis showed that the correlation between the language stimulation factor and child language was significantly and moderately due to shared genes. There is some suggestive evidence from longitudinal phenotypic analysis that the prediction from parental language stimulation to child language includes both evocative and passive gene-environment correlation, with the latter playing a larger role. The reader will understand why correlations between parental language and rate of child language are by themselves ambiguous, and how twin studies can clarify the relationship. The reader will also understand that, based on the present study, at least two aspects of parental language style - informal language stimulation and corrective feedback - have substantial genetic influence, and that for informal language stimulation, a substantial portion of the prediction to child language represents the effect of shared genes on both parent and child. It will also be appreciated that these basic research findings do not imply that parental language input style is unimportant or that interventions cannot be effective. Copyright

  17. Externally induced continuous variable entanglement in a correlated emission laser

    Energy Technology Data Exchange (ETDEWEB)

    Tesfa, Sintayehu [Physics Department, Addis Ababa University, PO Box 1176, Addis Ababa (Ethiopia)], E-mail: sint_tesfa@yahoo.com

    2008-07-28

    Analysis of the externally induced quantum features of the cavity radiation of the two-photon correlated emission laser is presented. It turns out that the pumping process induces atomic coherence accountable for observing entanglement in the cavity radiation as well as the nonclassical photon number correlation despite the arising vacuum fluctuations. Even though a significant continuous variable entanglement is obtained near threshold in the strong driving limit, increasing the amplitude of the driving radiation more than required for a fixed value of the linear gain coefficient is found to degrade the degree of entanglement. The two-mode squeezing of the superimposed radiation, entanglement of the cavity radiation and mean number of photon pairs increase with the rate at which the atoms are injected into the cavity, but the nonclassical photon number correlation decreases. Moreover, the mean photon number corresponding to the transition from the upper energy level to the intermediate is found to be greater than the transition from the intermediate to the lower. With conceivable practical challenges, it is in principle possible to generate an intense continuous variable entanglement and quantify it via photon count measurements.

  18. A DNA-based system for selecting and displaying the combined result of two input variables

    DEFF Research Database (Denmark)

    Liu, Huajie; Wang, Jianbang; Song, S

    2015-01-01

    Oligonucleotide-based technologies for biosensing or bio-regulation produce huge amounts of rich high-dimensional information. There is a consequent need for flexible means to combine diverse pieces of such information to form useful derivative outputs, and to display those immediately. Here we...... demonstrate this capability in a DNA-based system that takes two input numbers, represented in DNA strands, and returns the result of their multiplication, writing this as a number in a display. Unlike a conventional calculator, this system operates by selecting the result from a library of solutions rather...

  19. Improving land cover classification using input variables derived from a geographically weighted principal components analysis

    Science.gov (United States)

    Comber, Alexis J.; Harris, Paul; Tsutsumida, Narumasa

    2016-09-01

    This study demonstrates the use of a geographically weighted principal components analysis (GWPCA) of remote sensing imagery to improve land cover classification accuracy. A principal components analysis (PCA) is commonly applied in remote sensing but generates global, spatially-invariant results. GWPCA is a local adaptation of PCA that locally transforms the image data, and in doing so, can describe spatial change in the structure of the multi-band imagery, thus directly reflecting that many landscape processes are spatially heterogenic. In this research the GWPCA localised loadings of MODIS data are used as textural inputs, along with GWPCA localised ranked scores and the image bands themselves to three supervised classification algorithms. Using a reference data set for land cover to the west of Jakarta, Indonesia the classification procedure was assessed via training and validation data splits of 80/20, repeated 100 times. For each classification algorithm, the inclusion of the GWPCA loadings data was found to significantly improve classification accuracy. Further, but more moderate improvements in accuracy were found by additionally including GWPCA ranked scores as textural inputs, data that provide information on spatial anomalies in the imagery. The critical importance of considering both spatial structure and spatial anomalies of the imagery in the classification is discussed, together with the transferability of the new method to other studies. Research topics for method refinement are also suggested.

  20. Maximum-entropy distributions of correlated variables with prespecified marginals.

    Science.gov (United States)

    Larralde, Hernán

    2012-12-01

    The problem of determining the joint probability distributions for correlated random variables with prespecified marginals is considered. When the joint distribution satisfying all the required conditions is not unique, the "most unbiased" choice corresponds to the distribution of maximum entropy. The calculation of the maximum-entropy distribution requires the solution of rather complicated nonlinear coupled integral equations, exact solutions to which are obtained for the case of Gaussian marginals; otherwise, the solution can be expressed as a perturbation around the product of the marginals if the marginal moments exist.

  1. Quantum correlations in optical angle-orbital angular momentum variables.

    Science.gov (United States)

    Leach, Jonathan; Jack, Barry; Romero, Jacqui; Jha, Anand K; Yao, Alison M; Franke-Arnold, Sonja; Ireland, David G; Boyd, Robert W; Barnett, Stephen M; Padgett, Miles J

    2010-08-06

    Entanglement of the properties of two separated particles constitutes a fundamental signature of quantum mechanics and is a key resource for quantum information science. We demonstrate strong Einstein, Podolsky, and Rosen correlations between the angular position and orbital angular momentum of two photons created by the nonlinear optical process of spontaneous parametric down-conversion. The discrete nature of orbital angular momentum and the continuous but periodic nature of angular position give rise to a special sort of entanglement between these two variables. The resulting correlations are found to be an order of magnitude stronger than those allowed by the uncertainty principle for independent (nonentangled) particles. Our results suggest that angular position and orbital angular momentum may find important applications in quantum information science.

  2. Variable Structure Controller with Time-Varying Switching Surface under the Bound of Input using Evolution Strategy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Jung; Choi, Young Kiu [Pusan National University (Korea); Kim, Hyun Sik [Agency for Defense Development (Korea); Jeon, Seong Jeub [Pukyong National University (Korea)

    1999-04-01

    Variable structure control law is well known to be a robust control algorithm and evolution strategy is used as an effective search algorithm in optimization problems. In this paper, we propose a variable structure controller with time-varying switching surface. We calculate the maximum value of switching surface gradient under the bound of input. To enhance the robustness, we choose a time-varying switching surface gradient that is of the 3 rd order polynomial form. Evolution strategy is used to optimize the parameters of the switching surface gradient. Finally, the proposed method is applied to position tracking control for BLDC motor. Experimental results show that the proposed method is more useful than the conventional variable structure control. (author). 8 refs., 16 figs., 1 tab.

  3. Oscillatory Activity in Electrosensory Neurons Increases with the Spatial Correlation of the Stochastic Input Stimulus

    Science.gov (United States)

    Doiron, Brent; Lindner, Benjamin; Longtin, André; Maler, Leonard; Bastian, Joseph

    2004-07-01

    We present results from a novel experimental paradigm to investigate the influence of spatial correlations of stimuli on electrosensory neural network dynamics. Further, a new theoretical analysis for the dynamics of a model network of stochastic leaky integrate-and-fire neurons with delayed feedback is proposed. Experiment and theory for this system both establish that spatial correlations induce a network oscillation, the strength of which is proportional to the degree of stimulus correlation at constant total stimulus power.

  4. Variability of interconnected wind plants: correlation length and its dependence on variability time scale

    Science.gov (United States)

    St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.

    2015-04-01

    The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. But how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer ‘how far is far enough,’ we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25-2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high

  5. Experimental demonstration of continuous variable cloning with phase-conjugate inputs

    DEFF Research Database (Denmark)

    Sabuncu, Metin; Andersen, Ulrik Lund; Leuchs, G.

    2007-01-01

    We report the first experimental demonstration of continuous variable cloning of phase-conjugate coherent states as proposed by Cerf and Iblisdir [Phys. Rev. Lett. 87, 247903 (2001)]. In contrast to this proposal, the cloning transformation is accomplished using only linear optical components......, homodyne detection, and feedforward. As a result of combining phase conjugation with a joint measurement strategy, superior cloning is demonstrated with cloning fidelities reaching 89%....

  6. Using multiple-accumulator CMACs to improve efficiency of the X part of an input-buffered FX correlator

    Science.gov (United States)

    Lapshev, Stepan; Hasan, S. M. Rezaul

    2017-01-01

    This paper presents the approach of using complex multiplier-accumulators (CMACs) with multiple accumulators to reduce the total number of memory operations in an input-buffered architecture for the X part of an FX correlator. A processing unit of this architecture uses an array of CMACs that are reused for different groups of baselines. The disadvantage of processing correlations in this way is that each input data sample has to be read multiple times from the memory because each input signal is used in many of these baseline groups. While a one-accumulator CMAC cannot switch to a different baseline until it is finished integrating the current one, a multiple-accumulator CMAC can. Thus, the array of multiple-accumulator CMACs can switch between processing different baselines that share some input signals at any moment to reuse the current data in the processing buffers. In this way significant reductions in the number of memory read operations are achieved with only a few accumulators per CMAC. For example, for a large number of input signals three-accumulator CMACs reduce the total number of memory operations by more than a third. Simulated energy measurements of four VLSI designs in a high-performance 28 nm CMOS technology are presented in this paper to demonstrate that using multiple accumulators can also lead to reduced power dissipation of the processing array. Using three accumulators as opposed to one has been found to reduce the overall energy of 8-bit CMACs by 1.4% through the reduction of the switching activity within their circuits, which is in addition to a more than 30% reduction in the memory.

  7. Correlation-based analysis and generation of multiple spike trains using hawkes models with an exogenous input.

    Science.gov (United States)

    Krumin, Michael; Reutsky, Inna; Shoham, Shy

    2010-01-01

    The correlation structure of neural activity is believed to play a major role in the encoding and possibly the decoding of information in neural populations. Recently, several methods were developed for exactly controlling the correlation structure of multi-channel synthetic spike trains (Brette, 2009; Krumin and Shoham, 2009; Macke et al., 2009; Gutnisky and Josic, 2010; Tchumatchenko et al., 2010) and, in a related work, correlation-based analysis of spike trains was used for blind identification of single-neuron models (Krumin et al., 2010), for identifying compact auto-regressive models for multi-channel spike trains, and for facilitating their causal network analysis (Krumin and Shoham, 2010). However, the diversity of correlation structures that can be explained by the feed-forward, non-recurrent, generative models used in these studies is limited. Hence, methods based on such models occasionally fail when analyzing correlation structures that are observed in neural activity. Here, we extend this framework by deriving closed-form expressions for the correlation structure of a more powerful multivariate self- and mutually exciting Hawkes model class that is driven by exogenous non-negative inputs. We demonstrate that the resulting Linear-Non-linear-Hawkes (LNH) framework is capable of capturing the dynamics of spike trains with a generally richer and more biologically relevant multi-correlation structure, and can be used to accurately estimate the Hawkes kernels or the correlation structure of external inputs in both simulated and real spike trains (recorded from visually stimulated mouse retinal ganglion cells). We conclude by discussing the method's limitations and the broader significance of strengthening the links between neural spike train analysis and classical system identification.

  8. Comparison of friction stir welding heat transfer analysis methods and parametric study on unspecified input variables

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sung Wook; Jang, Beom Seon [Seoul National University, Seoul (Korea, Republic of)

    2014-10-15

    A three-dimensional numerical model was constructed to analyze the heat transfer of friction stir welding using Fluent and ANSYS multi-physics. The analysis result was used to calculate welding deformation and residual stress. Before the numerical simulation, several simplifying assumptions were applied to the model. Three different methods of heat transfer analysis were employed, and several assumptions were applied to each heat source model. In this work, several parametric studies were performed for certain unspecified variables. The calculated temperature data were compared with experimental data from relevant studies. Additionally, the advantages and disadvantages of the three heat transfer analysis methods were compared.

  9. Constraints on halo formation from cross-correlations with correlated variables

    CERN Document Server

    Castorina, Emanuele; Sheth, Ravi K

    2016-01-01

    Cross-correlations between biased tracers and the dark matter field encode information about the physical variables which characterize these tracers. However, if the physical variables of interest are correlated with one another, then extracting this information is not as straightforward as one might naively have thought. We show how to exploit these correlations so as to estimate scale-independent bias factors of all orders in a model-independent way. We also show that failure to account for this will lead to incorrect conclusions about which variables matter and which do not. Morever, accounting for this allows one to use the scale dependence of bias to constrain the physics of halo formation; to date the argument has been phrased the other way around. We illustrate by showing that the scale dependence of linear and nonlinear bias, measured on nonlinear scales, can be used to provide consistent estimates of how the critical density for halo formation depends on halo mass. Our methods work even when the bias...

  10. Paleodust variability since the Last Glacial Maximum and implications for iron inputs to the ocean

    Science.gov (United States)

    Albani, S.; Mahowald, N. M.; Murphy, L. N.; Raiswell, R.; Moore, J. K.; Anderson, R. F.; McGee, D.; Bradtmiller, L. I.; Delmonte, B.; Hesse, P. P.; Mayewski, P. A.

    2016-04-01

    Changing climate conditions affect dust emissions and the global dust cycle, which in turn affects climate and biogeochemistry. In this study we use observationally constrained model reconstructions of the global dust cycle since the Last Glacial Maximum, combined with different simplified assumptions of atmospheric and sea ice processing of dust-borne iron, to provide estimates of soluble iron deposition to the oceans. For different climate conditions, we discuss uncertainties in model-based estimates of atmospheric processing and dust deposition to key oceanic regions, highlighting the large degree of uncertainty of this important variable for ocean biogeochemistry and the global carbon cycle. We also show the role of sea ice acting as a time buffer and processing agent, which results in a delayed and pulse-like soluble iron release into the ocean during the melting season, with monthly peaks up to ~17 Gg/month released into the Southern Oceans during the Last Glacial Maximum (LGM).

  11. Optimization modeling of U.S. renewable electricity deployment using local input variables

    Science.gov (United States)

    Bernstein, Adam

    For the past five years, state Renewable Portfolio Standard (RPS) laws have been a primary driver of renewable electricity (RE) deployments in the United States. However, four key trends currently developing: (i) lower natural gas prices, (ii) slower growth in electricity demand, (iii) challenges of system balancing intermittent RE within the U.S. transmission regions, and (iv) fewer economical sites for RE development, may limit the efficacy of RPS laws over the remainder of the current RPS statutes' lifetime. An outsized proportion of U.S. RE build occurs in a small number of favorable locations, increasing the effects of these variables on marginal RE capacity additions. A state-by-state analysis is necessary to study the U.S. electric sector and to generate technology specific generation forecasts. We used LP optimization modeling similar to the National Renewable Energy Laboratory (NREL) Renewable Energy Development System (ReEDS) to forecast RE deployment across the 8 U.S. states with the largest electricity load, and found state-level RE projections to Year 2031 significantly lower than thoseimplied in the Energy Information Administration (EIA) 2013 Annual Energy Outlook forecast. Additionally, the majority of states do not achieve their RPS targets in our forecast. Combined with the tendency of prior research and RE forecasts to focus on larger national and global scale models, we posit that further bottom-up state and local analysis is needed for more accurate policy assessment, forecasting, and ongoing revision of variables as parameter values evolve through time. Current optimization software eliminates much of the need for algorithm coding and programming, allowing for rapid model construction and updating across many customized state and local RE parameters. Further, our results can be tested against the empirical outcomes that will be observed over the coming years, and the forecast deviation from the actuals can be attributed to discrete parameter

  12. Quasi-supervised scoring of human sleep in polysomnograms using augmented input variables.

    Science.gov (United States)

    Yaghouby, Farid; Sunderam, Sridhar

    2015-04-01

    The limitations of manual sleep scoring make computerized methods highly desirable. Scoring errors can arise from human rater uncertainty or inter-rater variability. Sleep scoring algorithms either come as supervised classifiers that need scored samples of each state to be trained, or as unsupervised classifiers that use heuristics or structural clues in unscored data to define states. We propose a quasi-supervised classifier that models observations in an unsupervised manner but mimics a human rater wherever training scores are available. EEG, EMG, and EOG features were extracted in 30s epochs from human-scored polysomnograms recorded from 42 healthy human subjects (18-79 years) and archived in an anonymized, publicly accessible database. Hypnograms were modified so that: 1. Some states are scored but not others; 2. Samples of all states are scored but not for transitional epochs; and 3. Two raters with 67% agreement are simulated. A framework for quasi-supervised classification was devised in which unsupervised statistical models-specifically Gaussian mixtures and hidden Markov models--are estimated from unlabeled training data, but the training samples are augmented with variables whose values depend on available scores. Classifiers were fitted to signal features incorporating partial scores, and used to predict scores for complete recordings. Performance was assessed using Cohen's Κ statistic. The quasi-supervised classifier performed significantly better than an unsupervised model and sometimes as well as a completely supervised model despite receiving only partial scores. The quasi-supervised algorithm addresses the need for classifiers that mimic scoring patterns of human raters while compensating for their limitations.

  13. Correlated X-ray/Ultraviolet/Optical Variability in NGC 6814

    CERN Document Server

    Troyer, Jon; Cackett, Edward; Bentz, Misty; Goad, Michael; Horne, Keith; Seals, James

    2015-01-01

    We present results of a 3-month combined X-ray/UV/optical monitoring campaign of the Seyfert 1 galaxy NGC 6814. The object was monitored by Swift from June through August 2012 in the X-ray and UV bands and by the Liverpool Telescope from May through July 2012 in B and V. The light curves are variable and significantly correlated between wavebands. Using cross-correlation analysis, we compute the time lag between the X-ray and lower energy bands. These lags are thought to be associated with the light travel time between the central X-ray emitting region and areas further out on the accretion disc. The computed lags support a thermal reprocessing scenario in which X-ray photons heat the disc and are reprocessed into lower energy photons. Additionally, we fit the lightcurves using CREAM, a Markov Chain Monte Carlo code for a standard disc. The best-fitting standard disc model yields unreasonably high super-Eddington accretion rates. Assuming more reasonable accretion rates would result in significantly under-pre...

  14. Predicting coral species richness: the effect of input variables, diversity and scale.

    Science.gov (United States)

    Richards, Zoe T; Hobbs, Jean-Paul A

    2014-01-01

    Coral reefs are facing a biodiversity crisis due to increasing human impacts, consequently, one third of reef-building corals have an elevated risk of extinction. Logistic challenges prevent broad-scale species-level monitoring of hard corals; hence it has become critical that effective proxy indicators of species richness are established. This study tests how accurately three potential proxy indicators (generic richness on belt transects, generic richness on point-intercept transects and percent live hard coral cover on point-intercept transects) predict coral species richness at three different locations and two analytical scales. Generic richness (measured on a belt transect) was found to be the most effective predictor variable, with significant positive linear relationships across locations and scales. Percent live hard coral cover consistently performed poorly as an indicator of coral species richness. This study advances the practical framework for optimizing coral reef monitoring programs and empirically demonstrates that generic richness offers an effective way to predict coral species richness with a moderate level of precision. While the accuracy of species richness estimates will decrease in communities dominated by species-rich genera (e.g. Acropora), generic richness provides a useful measure of phylogenetic diversity and incorporating this metric into monitoring programs will increase the likelihood that changes in coral species diversity can be detected.

  15. Predicting coral species richness: the effect of input variables, diversity and scale.

    Directory of Open Access Journals (Sweden)

    Zoe T Richards

    Full Text Available Coral reefs are facing a biodiversity crisis due to increasing human impacts, consequently, one third of reef-building corals have an elevated risk of extinction. Logistic challenges prevent broad-scale species-level monitoring of hard corals; hence it has become critical that effective proxy indicators of species richness are established. This study tests how accurately three potential proxy indicators (generic richness on belt transects, generic richness on point-intercept transects and percent live hard coral cover on point-intercept transects predict coral species richness at three different locations and two analytical scales. Generic richness (measured on a belt transect was found to be the most effective predictor variable, with significant positive linear relationships across locations and scales. Percent live hard coral cover consistently performed poorly as an indicator of coral species richness. This study advances the practical framework for optimizing coral reef monitoring programs and empirically demonstrates that generic richness offers an effective way to predict coral species richness with a moderate level of precision. While the accuracy of species richness estimates will decrease in communities dominated by species-rich genera (e.g. Acropora, generic richness provides a useful measure of phylogenetic diversity and incorporating this metric into monitoring programs will increase the likelihood that changes in coral species diversity can be detected.

  16. Digital Signal Processing using Stream High Performance Computing: A 512-input Broadband Correlator for Radio Astronomy

    CERN Document Server

    Kocz, J; Barsdell, B R; Price, D; Bernardi, G; Bourke, S; Clark, M A; Craig, J; Dexter, M; Dowell, J; Eftekhari, T; Ellingson, S; Hallinan, G; Hartman, J; Jameson, A; MacMahon, D; Taylor, G; Schinzel, F; Werthimer, D

    2014-01-01

    A "large-N" correlator that makes use of Field Programmable Gate Arrays and Graphics Processing Units has been deployed as the digital signal processing system for the Long Wavelength Array station at Owens Valley Radio Observatory (LWA-OV), to enable the Large Aperture Experiment to Detect the Dark Ages (LEDA). The system samples a ~100MHz baseband and processes signals from 512 antennas (256 dual polarization) over a ~58MHz instantaneous sub-band, achieving 16.8Tops/s and 0.236 Tbit/s throughput in a 9kW envelope and single rack footprint. The output data rate is 260MB/s for 9 second time averaging of cross-power and 1 second averaging of total-power data. At deployment, the LWA-OV correlator was the largest in production in terms of N and is the third largest in terms of complex multiply accumulations, after the Very Large Array and Atacama Large Millimeter Array. The correlator's comparatively fast development time and low cost establish a practical foundation for the scalability of a modular, heterogeneo...

  17. Constraints on halo formation from cross-correlations with correlated variables

    Science.gov (United States)

    Castorina, Emanuele; Paranjape, Aseem; Sheth, Ravi K.

    2017-07-01

    Cross-correlations between biased tracers and the dark matter field encode information about the physical variables that characterize these tracers. However, if the physical variables of interest are correlated with one another, then extracting this information is not as straightforward as one might naively have thought. We show how to exploit these correlations so as to estimate scale-independent bias factors of all orders in a model-independent way. We also show that failure to account for this will lead to incorrect conclusions about which variables matter and which do not. Moreover, accounting for this allows one to use the scale dependence of bias to constrain the physics of halo formation; to date, the argument has been phrased the other way around. We illustrate by showing that the scale dependence of linear and non-linear bias, measured on non-linear scales, can be used to provide consistent estimates of how the critical density for halo formation depends on halo mass. Our methods work even when the bias is non-local and stochastic, such as when, in addition to the spherically averaged density field and its derivatives, the quadrupolar shear field also matters for halo formation. In such models, the non-local bias factors are closely related to the more familiar local non-linear bias factors, which are much easier to measure. Our analysis emphasizes the fact that biased tracers are biased because they do not sample fields (density, velocity, shear, etc.) at all positions in space in the same way as the dark matter does.

  18. Channel capacity of multiple-input multiple-output systems with transmit and receive correlation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In order to investigate the impact of channel model parameters on the channel capacity of a multipleinput multiple-output (MIMO) system,a novel method is proposed to explore the channel capacity under Rayleigh flat fading with correlated transmit and receive antennas.The optimal transmitting direction which can achieve maximum channel capacity is derived using random matrices theory.In addition,the closed-form expression for the channel capacity of MIMO systems is given by utilizing the properties of Wishart distribution when SNR is high.Computer simulation results show that the channel capacity is maximized when the antenna spacing increases to a certain point,and furthermore,the larger the scattering angle is,the more quickly the channel capacity converges to its maximum.At high SNR (>12 dB),the estimation of capacity is close to its true value.And,when the same array configuration is adopted both at the transmitter and the receiver,the UCA yields higher channel capacity than ULA.

  19. On the correlation of nonlinear variables containing secular trend variations: numerical experiments

    Institute of Scientific and Technical Information of China (English)

    Shi Neng; Yi Yan-Ming; Gu Jun-Qiang; Xia Dong-Dong

    2006-01-01

    Due to global warming, the general circulation, underlying surfaces characteristics, and geophysical and meteorological elements all show evident secular trends. This paper points out that when calculating the correlation of two variables containing their own obvious secular trends, the interannual correlation characteristics between the two variables may be distorted (overestimated or underestimated). Numerical experiments in this paper show that if two variables have opposite secular trends, the correlation coefficient between the two variables is reduced (the positive correlation is underestimated, or the negative correlation is overestimated); and if the two variables have the same sign of secular trends, the correlation coefficient between the two variables is increased (the positive correlation is overestimated,or the negative correlation is underestimated). Numerical experiments also suggest that the effect of secular trends on the interannual correlation of the two variables is interchangeable, that is to say, as long as the values of the two trends are not changed, the two variables interchange their positions, and the effect of the secular trends on the interannual correlation coefficient of the two variables remains the same. If the two variables have the same-(opposite-) sign trends,the effect of secular trends on the interannual correlation coefficient is more (less) distinctive. A meteorological example is given.

  20. Decomposing age correlations on neuropsychological and cognitive variables

    Science.gov (United States)

    SALTHOUSE, TIMOTHY A.

    2013-01-01

    Individual differences associated with age and various neurological conditions are often found in many different neuropsychological and cognitive variables. These variables are frequently treated as though they were independent of one another, with the results interpreted in terms of effects on task-specific processes. However, an alternative perspective evaluates the breadth of the individual difference influences, and takes relations with other variables into account when considering effects on specific neurocognitive variables. This analytical procedure is illustrated in analyses of the WAIS-IV and WMS-IV standardization data, and of data from the Virginia Cognitive Aging Project. PMID:19570312

  1. Rapid Variability: What do we learn from correlated mm-/gamma-ray variability in jets ?

    CERN Document Server

    Rani, B; Fuhrmann, L; Lott, B; Boettcher, M; Zensus, J A

    2013-01-01

    Densely time sampled multi-frequency flux measurements of the extreme BL Lac object S5 0716+714 over the past three years allow us to study its broad-band variability, and the detailed underlying physics, with emphasis on the location and size of the emitting regions and the evolution with time. We study the characteristics of some prominent mm-/gamma-ray flares in the context of the shock-in-jet model and investigate the location of the high energy emission region. The rapid rise and decay of the radio flares is in agreement with the formation of a shock and its evolution, if a geometrical variation is included in addition to intrinsic variations of the source. We find evidence for a correlation between flux variations at gamma-ray and radio frequencies. A two month time-delay between gamma-ray and radio flares indicates a non-cospatial origin of gamma-rays and radio flux variations in S5 0716+714.

  2. Effect of the spatiotemporal variability of rainfall inputs in water quality integrated catchment modelling for dissolved oxygen concentrations

    Science.gov (United States)

    Moreno Ródenas, Antonio Manuel; Cecinati, Francesca; ten Veldhuis, Marie-Claire; Langeveld, Jeroen; Clemens, Francois

    2016-04-01

    Maintaining water quality standards in highly urbanised hydrological catchments is a worldwide challenge. Water management authorities struggle to cope with changing climate and an increase in pollution pressures. Water quality modelling has been used as a decision support tool for investment and regulatory developments. This approach led to the development of integrated catchment models (ICM), which account for the link between the urban/rural hydrology and the in-river pollutant dynamics. In the modelled system, rainfall triggers the drainage systems of urban areas scattered along a river. When flow exceeds the sewer infrastructure capacity, untreated wastewater enters the natural system by combined sewer overflows. This results in a degradation of the river water quality, depending on the magnitude of the emission and river conditions. Thus, being capable of representing these dynamics in the modelling process is key for a correct assessment of the water quality. In many urbanised hydrological systems the distances between draining sewer infrastructures go beyond the de-correlation length of rainfall processes, especially, for convective summer storms. Hence, spatial and temporal scales of selected rainfall inputs are expected to affect water quality dynamics. The objective of this work is to evaluate how the use of rainfall data from different sources and with different space-time characteristics affects modelled output concentrations of dissolved oxygen in a simplified ICM. The study area is located at the Dommel, a relatively small and sensitive river flowing through the city of Eindhoven (The Netherlands). This river stretch receives the discharge of the 750,000 p.e. WWTP of Eindhoven and from over 200 combined sewer overflows scattered along its length. A pseudo-distributed water quality model has been developed in WEST (mikedhi.com); this is a lumped-physically based model that accounts for urban drainage processes, WWTP and river dynamics for several

  3. Continuous variable entanglement in a coherently pumped correlated emission laser

    Energy Technology Data Exchange (ETDEWEB)

    Tesfa, Sintayehu [Physics Department, Addis Ababa University, PO Box 1176, Addis Ababa (Ethiopia)], E-mail: sint_tesfa@yahoo.com

    2008-03-14

    Analysis of the effects of external pumping on the quantum features of cavity radiation of the two-photon correlated emission laser is presented. It turns out that the pumping process induces the atomic coherence responsible for the entanglement of the cavity radiation as well as the correlation between the photon numbers belonging to different modes, despite the arising vacuum fluctuations. The photon number correlation is found to be very close to 2 where the entanglement is relatively better. Moreover, the mean number of photon pairs decreases with the amplitude of the driving radiation which is one of the practical limitations associated with the pumping mechanism. It is also shown that the mean photon number of the radiation in mode b is less than one-third of that in mode a.

  4. Ergodic channel capacity of spatial correlated multiple-input multiple-output free space optical links using multipulse pulse-position modulation

    Science.gov (United States)

    Wang, Huiqin; Wang, Xue; Cao, Minghua

    2017-02-01

    The spatial correlation extensively exists in the multiple-input multiple-output (MIMO) free space optical (FSO) communication systems due to the channel fading and the antenna space limitation. Wilkinson's method was utilized to investigate the impact of spatial correlation on the MIMO FSO communication system employing multipulse pulse-position modulation. Simulation results show that the existence of spatial correlation reduces the ergodic channel capacity, and the reception diversity is more competent to resist this kind of performance degradation.

  5. Logistic regression when binary predictor variables are highly correlated.

    Science.gov (United States)

    Barker, L; Brown, C

    Standard logistic regression can produce estimates having large mean square error when predictor variables are multicollinear. Ridge regression and principal components regression can reduce the impact of multicollinearity in ordinary least squares regression. Generalizations of these, applicable in the logistic regression framework, are alternatives to standard logistic regression. It is shown that estimates obtained via ridge and principal components logistic regression can have smaller mean square error than estimates obtained through standard logistic regression. Recommendations for choosing among standard, ridge and principal components logistic regression are developed. Published in 2001 by John Wiley & Sons, Ltd.

  6. Genetic variability and correlation studies in sunflower (Helianthus annuus L.

    Directory of Open Access Journals (Sweden)

    Sheshaiah and Shankergoud I.

    2015-06-01

    Full Text Available The present study was conducted in order to investigate genetic variability and to understand the relationship and contribution of characters towards total dry matter and root length. The investigation was carried out at Main Agricultural Research Station, UAS, Raichur during Rabi 2012-13, 32 genotypes were evaluated in RBD fashion under root structures. At flowering stage all morphological and root characters were scored. The total dry matter content was assessed after drying the root, stem, leaf, petiole and flower of the plant at 70 0C in an oven.. High GCV coupled with high PCV recorded for most of the characters except stem girth, SPAD reading and number of leaves, indicating more variability for these traits and are less influenced by the environment. High heritability coupled with high GAM reported for all the traits under study suggested for the greater effectiveness for selection and improvement expected for these traits in future generations. The total dry matter and root length had very highly significant positive association with plant height, root volume, fresh root weight, dry root weight, fresh stem weight, dry stem weight, fresh leaf weight and dry leaf weight indicating the importance of root characters in determining the moisture stress tolerance and putforthing the total dry matter content of the plant.

  7. Neural network with a self-selection ability of input variables for a nonlinear system identification; Nyuryoku hensu no jiko sentaku noryoku wo sonaeta hisenkei system dotei yo neural network

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, T. [School of Medical Sciences, The University of Tokushima., Tokushima (Japan)

    1997-08-31

    When neural network is applied to identification problem with complex structure, structure of the network becomes larger in its scale and more complex as its input variables increase, because of necessity on effect of high order in the input variable within the network. In this study, a neural network with self-selection ability of the input variables is proposed. This network can remove the neuron related to the input variables from inner portion of the network according to the prediction error estimation standard and construct a neural network only by means of the neuron related to useful input variables, even when it contains unnecessary variables for its input variable. In this paper, by comparing with identification results obtained by conventional neural network or improved GMDH method, its effectiveness could be elucidated. And, it applied to short-term forecasting problem of air pollution concentration, to compare its estimation accuracy with those of other prediction models. 18 refs., 10 figs., 3 tabs.

  8. Variability of energy input into selected subsystems of the human-glove-tool system: a theoretical study.

    Science.gov (United States)

    Hermann, Tomasz; Dobry, Marian Witalis

    2017-05-31

    This article presents an application of the energy method to assess the energy input introduced into two subsystems of the human-glove-tool system. To achieve this aim, a physical model of the system was developed. This consists of dynamic models of the human body and the glove described in Standard No. ISO 10068:2012, and a model of a hand-held power tool. The energy input introduced into the subsystems, i.e., the human body and the glove, was analysed in the domain of energy and involved calculating three component energy inputs of forces. The energy model was solved using numerical simulation implemented in the MATLAB/simulink environment. This procedure demonstrates that the vibration energy was distributed quite differently in the internal structure of the two subsystems. The results suggest that the operating frequency of the tool has a significant impact on the level of energy inputs transmitted into both subsystems.

  9. Geostatistical independent simulation of spatially correlated soil variables

    Science.gov (United States)

    Boluwade, Alaba; Madramootoo, Chandra A.

    2015-12-01

    The selection of best management practices to reduce soil and water pollution often requires estimation of soil properties. It is important to find an efficient and robust technique to simulate spatially correlated soils parameters. Co-kriging and co-simulation are techniques that can be used. These methods are limited in terms of computer simulation due to the problem of solving large co-kriging systems and difficulties in fitting a valid model of coregionalization. The order of complexity increases as the number of covariables increases. This paper presents a technique for the conditional simulation of a non-Gaussian vector random field on point support scale. The technique is termed Independent Component Analysis (ICA). The basic principle underlining ICA is the determination of a linear representation of non-Gaussian data so that the components are considered statistically independent. With such representation, it would be easy and more computationally efficient to develop direct variograms for the components. The process is presented in two stages. The first stage involves the ICA decomposition. The second stage involves sequential Gaussian simulation of the generated components (which are derived from the first stage). This technique was applied for spatially correlated extractable cations such as magnesium (Mg) and iron (Fe) in a Canadian watershed. This paper has a strong application in stochastic quantification of uncertainties of soil attributes in soil remediation and soil rehabilitation.

  10. APPLICATION OF FRF ESTIMATOR BASED ON ERRORS-IN-VARIABLES MODEL IN MULTI-INPUT MULTI-OUTPUT VIBRATION CONTROL SYSTEM

    Institute of Scientific and Technical Information of China (English)

    GUAN Guangfeng; CONG Dacheng; HAN Junwei; LI Hongren

    2007-01-01

    The FRF estimator based on the errors-in-variables (EV) model of multi-input multi-output (MIMO) System is presented to reduce the bias error of FRF Hl estimator. The FRF Hl estimator is influenced by the noises in the inputs of the System and generates an under-estimation of the true FRF. The FRF estimator based on the EV model takes into account the errors in both the inputs and Outputs of the System and would lead to more accurate FRF estimation. The FRF estimator based on the EV model is applied to the waveform replication on the 6-DOF (degree-of-freedom) hydraulic Vibration table. The result shows that it is favorable to improve the control precision of the MIMO Vibration control system.

  11. Measurement method for urine puddle depth in dairy cow houses as input variable for ammonia emission modelling

    NARCIS (Netherlands)

    Snoek, J.W.; Stigter, J.D.; Ogink, Nico; Groot Koerkamp, P.W.G.

    2015-01-01

    Dairy cow houses are a major contributor to ammonia (NH3) emission in many European countries. To understand and predict NH3 emissions from cubicle dairy cow houses a mechanistic model was developed and a sensitivity analysis was performed to assess the contribution to NH3 emission of each input var

  12. Measurement method for urine puddle depth in dairy cow houses as input variable for ammonia emission modelling

    NARCIS (Netherlands)

    Snoek, J.W.; Stigter, J.D.; Ogink, Nico; Groot Koerkamp, P.W.G.

    2015-01-01

    Dairy cow houses are a major contributor to ammonia (NH3) emission in many European countries. To understand and predict NH3 emissions from cubicle dairy cow houses a mechanistic model was developed and a sensitivity analysis was performed to assess the contribution to NH3 emission of each input

  13. Approximate entropy and point correlation dimension of heart rate variability in healthy subjects

    DEFF Research Database (Denmark)

    Storella, R J; Wood, H W; Mills, K M;

    1999-01-01

    The contribution of nonlinear dynamics to heart rate variability in healthy humans was examined using surrogate data analysis. Several measures of heart rate variability were used and compared. Heart rates were recorded for three hours and original data sets of 8192 R-R intervals created. For each...... original data set (n = 34), three surrogate data sets were made by shuffling the order of the R-R intervals while retaining their linear correlations. The difference in heart rate variability between the original and surrogate data sets reflects the amount of nonlinear structure in the original data set....... Heart rate variability was analyzed by two different nonlinear methods, point correlation dimension and approximate entropy. Nonlinearity, though under 10 percent, could be detected with both types of heart rate variability measures. More importantly, not only were the correlations between...

  14. A CATASTROPHIC-CUM-RESTORATIVE QUEUING SYSTEM WITH CORRELATED BATCH ARRIVALS AND VARIABLE CAPACITY

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar

    2008-07-01

    Full Text Available In this paper, we study a catastrophic-cum-restorative queuing system with correlated batch arrivals and service in batches of variable sizes. We perform the transient analysis of the queuing model. We obtain the Laplace Transform of the probability generating function of system size. Finally, some particular cases of the model have been derived and discussed. Keywords: Queue length, Catastrophes, Correlated batch arrivals, Broadband services, Variable service capacity, and Restoration.

  15. Sensitivity of Average Annual Runoff to Spatial Variability and Temporal Correlation of Rainfall.

    Science.gov (United States)

    Babin, Steven M.

    1995-08-01

    This paper examines the sensitivity of annual area mean runoff calculations to the effects of spatial variability and temporal correlation of rainfall. The model used is based upon the hypothesis that the annual water balance is determined only by rainfall, potential evapotranspiration, and soil water storage. A simple bucket hydrology model with a seasonally varying potential evapotranspiration is used with rainfall data measured at several sites on the Delmarva Peninsula. Annual area mean runoffs are calculated for three cases: 1) actual spatial variability among the rain gauge sites and temporal correlation between consecutive 1-min rainfall amounts are maintained (the actual case); 2) actual spatial variability among the sites is maintained but temporal correlation between the consecutive 1-min rainfall amounts is minimized (the site-shuffled case); and 3) both spatial variability and temporal correlation are ignored (the area-averaged case). The actual case represents the baseline for comparison with the other two cases. The annual a' mean runoffs show little sensitivity to spatial variability and temporal correlation for this model. Therefore, if finite soil permeability effects are ignored in favor of simple water storage capacity, then spatial variability and temporal correlation of rainfall appear to have little impact on the annual area mean runoff for the data considered in this study.

  16. LARGE DEVIATION FOR THE EMPIRICAL CORRELATION COEFFICIENT OF TWO GAUSSIAN RANDOM VARIABLES

    Institute of Scientific and Technical Information of China (English)

    Shen Si

    2007-01-01

    In this article, the author obtains the large deviation principles for the empirical correlation coefficient of two Gaussian random variables X and Y. Especially, when considering two independent Gaussian random variables X, Y with the means EX, EY(both known), wherein the author gives two kinds of different proofs and gets the same results.

  17. Effect of integral yoga on psychological and health variables and their correlations.

    Science.gov (United States)

    Khemka, Sushil S; Ramarao, Nagendra Hongasandra; Hankey, Alex

    2011-07-01

    Certain psychological and health variables are commonly measured in India. This study evaluates the effects of integral yoga practices on these variables and also the consistency of correlations observed between them. The study was a pre-post intervention study. The variables were measured at the beginning and the end of a one-month yoga course. There was no control group.The study was carried out at Swami Vivekananda Yoga Anusandhana Samsthana (S-VYASA) University, in its rural campus south of Bangalore. Based on health criteria, 108 subjects were selected out of 198 volunteers to form the experimental yoga group. Ages ranged from 17 to 63 years. The yogasanas (postures), pranayama (breathing exercises), relaxation techniques, meditation, chanting and lectures were the components of yoga intervention. The variables measured were sustained attention, emotional intelligence - EQ, general health - GHQ, guna personality - sattva, rajas and tamas. Significant pre-post changes were found in all variables. Significant correlations were found between the following pairs: The two sustained attention variables; emotional intelligence and general health; GHQ and tamas; sattva and tamas; and rajas and tamas. The study shows that there were significant changes in all variables (PEQ and general health variables correlate significantly with each other and negatively with tamas. EQ and tamas form positive and negative predictors of health respectively. Sattva correlates positively with EQ suggesting that a sattvic personality indicates better self-control. This suggests that, by improving guna personality, long-term yoga practice may stabilize EQ.

  18. A Correlational Study of Preadmission Predictor Variables and Dental School Performance.

    Science.gov (United States)

    Kress, Gerard C.; Dogon, I. Leon

    1981-01-01

    Undergraduate performance and standardized test scores were correlated with dental school performance for 131 members of nine Harvard School of Dental Medicine classes to determine the predictive validity of the earlier variables. The only significant positive correlation was of the Dental Admission Test and dental National Board Examination, part…

  19. Effect of integral yoga on psychological and health variables and their correlations

    Directory of Open Access Journals (Sweden)

    Sushil S Khemka

    2011-01-01

    Results: Significant pre-post changes were found in all variables. Significant correlations were found between the following pairs: The two sustained attention variables; emotional intelligence and general health; GHQ and tamas; sattva and tamas; and rajas and tamas. Conclusion: The study shows that there were significant changes in all variables (P< 0.001 except in sattva. It also confirms that EQ and general health variables correlate significantly with each other and negatively with tamas. EQ and tamas form positive and negative predictors of health respectively. Sattva correlates positively with EQ suggesting that a sattvic personality indicates better self-control. This suggests that, by improving guna personality, long-term yoga practice may stabilize EQ.

  20. Complex principal component and correlation structure of 16 yeast genomic variables.

    Science.gov (United States)

    Theis, Fabian J; Latif, Nadia; Wong, Philip; Frishman, Dmitrij

    2011-09-01

    A quickly growing number of characteristics reflecting various aspects of gene function and evolution can be either measured experimentally or computed from DNA and protein sequences. The study of pairwise correlations between such quantitative genomic variables as well as collective analysis of their interrelations by multidimensional methods have delivered crucial insights into the processes of molecular evolution. Here, we present a principal component analysis (PCA) of 16 genomic variables from Saccharomyces cerevisiae, the largest data set analyzed so far. Because many missing values and potential outliers hinder the direct calculation of principal components, we introduce the application of Bayesian PCA. We confirm some of the previously established correlations, such as evolutionary rate versus protein expression, and reveal new correlations such as those between translational efficiency, phosphorylation density, and protein age. Although the first principal component primarily contrasts genomic change and protein expression, the second component separates variables related to gene existence and expressed protein functions. Enrichment analysis on genes affecting variable correlations unveils classes of influential genes. For example, although ribosomal and nuclear transport genes make important contributions to the correlation between protein isoelectric point and molecular weight, protein synthesis and amino acid metabolism genes help cause the lack of significant correlation between propensity for gene loss and protein age. We present the novel Quagmire database (Quantitative Genomics Resource) which allows exploring relationships between more genomic variables in three model organisms-Escherichia coli, S. cerevisiae, and Homo sapiens (http://webclu.bio.wzw.tum.de:18080/quagmire).

  1. Detection of land surface memory by correlations between thickness of colluvial deposits and morphometric variables

    Science.gov (United States)

    Mitusov, A. V.; Dreibrodt, S.; Mitusova, O. E.; Khamnueva, S. V.; Bork, H.-R.

    2013-06-01

    Some morphometric variables store information about past land surfaces longer than others. This property of morphometric variables is recognised as land surface memory. Slope deposits, soils, and vegetation also have this memory. In this study, a memory effect was quantitatively detected by Spearman correlations between thickness of colluvium and morphometric variables of the modern land surface. During long-term sedimentation, the sign of horizontal curvature (kh) may be inverted from minus to plus, suggesting that locations with positive kh values are not accumulation zones. However, the thickness of colluvial deposits at such locations in our study area indicates sediment accumulation. The sign of minimal curvature (kmin) tends to be more stable and remains negative. This difference provides the stronger correlation of colluvial layer thickness with kmin than with kh. The strongest correlation was found for total thickness of the colluvial deposits of the Neolithic and Iron Age with kmin (- 0.84); the correlation with kh was weaker (- 0.71).

  2. VARIABLE-RATE MULTIUSER DIVERSITY IN CORRELATED MIMO CHANNEL VIA VIRTUAL CHANNEL REPRESENTATION

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper studies the multiuser diversity with constellation selection based on a virtual representation of realistic Multiple Input Multiple Output (MIMO) correlated channels. To realize multiuser diversity in slow fading channels, random beamforming is adopted. Random beamforming matrix exploiting virtual channel representation is constructed, which can match the channel matrix of the desired user better. Simultaneously, adaptive coded modulation is applied to each sub-channel of the selected user to improve the system performance further.

  3. Derivation and analysis on the analytical structure of interval type-2 fuzzy controller with two nonlinear fuzzy sets for each input variable

    Institute of Scientific and Technical Information of China (English)

    Bin-bin LEI; Xue-chao DUAN; Hong BAO; Qian XU

    2016-01-01

    Type-2 fuzzy controllers have been mostly viewed as black-box function generators. Revealing the analytical struc-ture of any type-2 fuzzy controller is important as it will deepen our understanding of how and why a type-2 fuzzy controller functions and lay a foundation for more rigorous system analysis and design. In this study, we derive and analyze the analytical structure of an interval type-2 fuzzy controller that uses the following identical elements: two nonlinear interval type-2 input fuzzy sets for each variable, four interval type-2 singleton output fuzzy sets, a Zadeh AND operator, and the Karnik-Mendel type reducer. Through dividing the input space of the interval type-2 fuzzy controller into 15 partitions, the input-output relationship for each local region is derived. Our derivation shows explicitly that the controller is approximately equivalent to a nonlinear proportional integral or proportional differential controller with variable gains. Furthermore, by comparing with the analytical structure of its type-1 counterpart, potential advantages of the interval type-2 fuzzy controller are analyzed. Finally, the reliability of the analysis results and the effectiveness of the interval type-2 fuzzy controller are verified by a simulation and an experiment.

  4. Effect of variable annual precipitation and nutrient input on nitrogen and phosphorus transport from two Midwestern agricultural watersheds

    Science.gov (United States)

    Kalkhoff, Stephen J.; Hubbard, Laura E.; Tomer, Mark D.; James, D.E.

    2016-01-01

    Precipitation patterns and nutrient inputs affect transport of nitrate (NO3-N) and phosphorus (TP) from Midwest watersheds. Nutrient concentrations and yields from two subsurface-drained watersheds, the Little Cobb River (LCR) in southern Minnesota and the South Fork Iowa River (SFIR) in northern Iowa, were evaluated during 1996–2007 to document relative differences in timings and amounts of nutrients transported. Both watersheds are located in the prairie pothole region, but the SFIR exhibits a longer growing season and more livestock production. The SFIR yielded significantly more NO3-N than the LCR watershed (31.2 versus 21.3 kg NO3-N ha− 1 y− 1). The SFIR watershed also yielded more TP than the LCR watershed (1.13 versus 0.51 kg TP ha− 1 yr− 1), despite greater TP concentrations in the LCR. About 65% of NO3-N and 50% of TP loads were transported during April–June, and < 20% of the annual loads were transported later in the growing season from July–September. Monthly NO3-N and TP loads peaked in April from the LCR but peaked in June from the SFIR; this difference was attributed to greater snowmelt runoff in the LCR. The annual NO3-N yield increased with increasing annual runoff at a similar rate in both watersheds, but the LCR watershed yielded less annual NO3-N than the SFIR for a similar annual runoff. These two watersheds are within 150 km of one another and have similar dominant agricultural systems, but differences in climate and cropping inputs affected amounts and timing of nutrient transport.

  5. Input Correlations for Irradiation Creep of FeCrAl and SiC Based on In-Pile Halden Test Results

    Energy Technology Data Exchange (ETDEWEB)

    Terrani, K. A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Karlsen, T. M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-05-01

    Swelling and creep behavior of wrought FeCrAl alloys and CVD-SiC, two candidate accident tolerant fuel cladding materials, are being examined using in-pile tests at the Halden reactor. The outcome of these tests are material property correlations that are inputs into fuel performance analysis tools. The results are discussed and compared with what is available in literature from irradiation experiments in other reactors or out-of-pile tests. Specific recommendation on what correlations should be used for swelling, thermal, and irradiation creep for each material are provided in this document.

  6. Correlations of control variables for horizontal background error covariance modeling on cubed-sphere grid

    Science.gov (United States)

    Kwun, Jihye; Song, Hyo-Jong; Park, Jong-Im

    2013-04-01

    Background error covariance matrix is very important for variational data assimilation system, determining how the information from observed variables is spread to unobserved variables and spatial points. The full representation of the matrix is impossible because of the huge size so the matrix is constructed implicitly by means of a variable transformation. It is assumed that the forecast errors in the control variables chosen are statistically independent. We used the cubed-sphere geometry based on the spectral element method which is better for parallel application. In cubed-sphere grids, the grid points are located at Gauss-Legendre-Lobatto points on each local element of 6 faces on the sphere. The two stages of the transformation were used in this study. The first is the variable transformation from model to a set of control variables whose errors are assumed to be uncorrelated, which was developed on the cubed sphere-using Galerkin method. Winds are decomposed into rotational part and divergent part by introducing stream function and velocity potential as control variables. The dynamical constraint for balance between mass and wind were made by applying linear balance operator. The second is spectral transformation which is to remove the remaining spatial correlation. The bases for the spectral transform were generated for the cubed-sphere grid. 6-hr difference fields of shallow water equation (SWE) model run initialized by variational data assimilation system were used to obtain forecast error statistics. In the horizontal background error covariance modeling, the regression analysis of the control variables was performed to define the unbalanced variables as the difference between full and correlated part. Regression coefficient was used to remove the remaining correlations between variables.

  7. The use of variable-step delta modulation in digital filtering and correlation analysis

    Science.gov (United States)

    Pogribnoi, V. A.

    1985-11-01

    General expressions are obtained for convolutions and correlation functions using variable-quantization-step DM in conjunction with PCM, making it possible to realize low-cost processor circuits. Algorithms for the operation of processors for digital filtering and correlation analysis on the basis of this type of modulation are proposed. In addition, they are compared with algorithms for the operation of processors with linear PCM, DM, and delta-sigma modulation.

  8. TESTING SERIAL CORRELATION IN SEMIPARAMETRIC VARYING COEFFICIENT PARTIALLY LINEAR ERRORS-IN-VARIABLES MODEL

    Institute of Scientific and Technical Information of China (English)

    Xuemei HU; Feng LIU; Zhizhong WANG

    2009-01-01

    The authors propose a V_(N,P) test statistic for testing finite-order serial correlation in a semiparametric varying coefficient partially linear errors-in-variables model. The test statistic is shown to have asymptotic normal distribution under the null hypothesis of no serial correlation. Some Monte Carlo experiments are conducted to examine the finite sample performance of the proposed V_(N,P) test statistic. Simulation results confirm that the proposed test performs satisfactorily in estimated size and power.

  9. Determination of the Optimal Training Principle and Input Variables in Artificial Neural Network Model for the Biweekly Chlorophyll-a Prediction: A Case Study of the Yuqiao Reservoir, China

    Science.gov (United States)

    Liu, Yu; Xi, Du-Gang; Li, Zhao-Liang

    2015-01-01

    Predicting the levels of chlorophyll-a (Chl-a) is a vital component of water quality management, which ensures that urban drinking water is safe from harmful algal blooms. This study developed a model to predict Chl-a levels in the Yuqiao Reservoir (Tianjin, China) biweekly using water quality and meteorological data from 1999-2012. First, six artificial neural networks (ANNs) and two non-ANN methods (principal component analysis and the support vector regression model) were compared to determine the appropriate training principle. Subsequently, three predictors with different input variables were developed to examine the feasibility of incorporating meteorological factors into Chl-a prediction, which usually only uses water quality data. Finally, a sensitivity analysis was performed to examine how the Chl-a predictor reacts to changes in input variables. The results were as follows: first, ANN is a powerful predictive alternative to the traditional modeling techniques used for Chl-a prediction. The back program (BP) model yields slightly better results than all other ANNs, with the normalized mean square error (NMSE), the correlation coefficient (Corr), and the Nash-Sutcliffe coefficient of efficiency (NSE) at 0.003 mg/l, 0.880 and 0.754, respectively, in the testing period. Second, the incorporation of meteorological data greatly improved Chl-a prediction compared to models solely using water quality factors or meteorological data; the correlation coefficient increased from 0.574-0.686 to 0.880 when meteorological data were included. Finally, the Chl-a predictor is more sensitive to air pressure and pH compared to other water quality and meteorological variables. PMID:25768650

  10. An Examination of the Demographic and Environmental Variables Correlated with Lyme Disease Emergence in Virginia.

    Science.gov (United States)

    Seukep, Sara E; Kolivras, Korine N; Hong, Yili; Li, Jie; Prisley, Stephen P; Campbell, James B; Gaines, David N; Dymond, Randel L

    2015-12-01

    Lyme disease is the United States' most significant vector-borne illness. Virginia, on the southern edge of the disease's currently expanding range, has experienced an increase in Lyme disease both spatially and temporally, with steadily increasing rates over the past decade and disease spread from the northern to the southwestern part of the state. This study used a Geographic Information System and a spatial Poisson regression model to examine correlations between demographic and land cover variables, and human Lyme disease from 2006 to 2010 in Virginia. Analysis indicated that herbaceous land cover is positively correlated with Lyme disease incidence rates. Areas with greater interspersion between herbaceous and forested land were also positively correlated with incidence rates. In addition, income and age were positively correlated with incidence rates. Levels of development, interspersion of herbaceous and developed land, and population density were negatively correlated with incidence rates. Abundance of forest fragments less than 2 hectares in area was not significantly correlated. Our results support some findings of previous studies on ecological variables and Lyme disease in endemic areas, but other results have not been found in previous studies, highlighting the potential contribution of new variables as Lyme disease continues to emerge southward.

  11. Photoreceptor processing speed and input resistance changes during light adaptation correlate with spectral class in the bumblebee, Bombus impatiens.

    Directory of Open Access Journals (Sweden)

    Peter Skorupski

    Full Text Available Colour vision depends on comparison of signals from photoreceptors with different spectral sensitivities. However, response properties of photoreceptor cells may differ in ways other than spectral tuning. In insects, for example, broadband photoreceptors, with a major sensitivity peak in the green region of the spectrum (>500 nm, drive fast visual processes, which are largely blind to chromatic signals from more narrowly-tuned photoreceptors with peak sensitivities in the blue and UV regions of the spectrum. In addition, electrophysiological properties of the photoreceptor membrane may result in differences in response dynamics of photoreceptors of similar spectral class between species, and different spectral classes within a species. We used intracellular electrophysiological techniques to investigate response dynamics of the three spectral classes of photoreceptor underlying trichromatic colour vision in the bumblebee, Bombus impatiens, and we compare these with previously published data from a related species, Bombus terrestris. In both species, we found significantly faster responses in green, compared with blue- or UV-sensitive photoreceptors, although all 3 photoreceptor types are slower in B. impatiens than in B. terrestris. Integration times for light-adapted B. impatiens photoreceptors (estimated from impulse response half-width were 11.3 ± 1.6 ms for green photoreceptors compared with 18.6 ± 4.4 ms and 15.6 ± 4.4 for blue and UV, respectively. We also measured photoreceptor input resistance in dark- and light-adapted conditions. All photoreceptors showed a decrease in input resistance during light adaptation, but this decrease was considerably larger (declining to about 22% of the dark value in green photoreceptors, compared to blue and UV (41% and 49%, respectively. Our results suggest that the conductances associated with light adaptation are largest in green photoreceptors, contributing to their greater temporal processing speed

  12. Using the Iterative Input variable Selection (IIS) algorithm to assess the relevance of ENSO teleconnections patterns on hydro-meteorological processes at the catchment scale

    Science.gov (United States)

    Beltrame, Ludovica; Carbonin, Daniele; Galelli, Stefano; Castelletti, Andrea

    2014-05-01

    Population growth, water scarcity and climate change are three major factors making the understanding of variations in water availability increasingly important. Therefore, reliable medium-to-long range forecasts of streamflows are essential to the development of water management policies. To this purpose, recent modelling efforts have been dedicated to seasonal and inter-annual streamflow forecasts based on the teleconnection between "at-site" hydro-meteorological processes and low frequency climate fluctuations, such as El Niño Southern Oscillation (ENSO). This work proposes a novel procedure for first detecting the impact of ENSO on hydro-meteorological processes at the catchment scale, and then assessing the potential of ENSO indicators for building medium-to-long range statistical streamflow prediction models. Core of this procedure is the adoption of the Iterative Input variable Selection (IIS) algorithm that is employed to find the most relevant forcings of streamflow variability and derive predictive models based on the selected inputs. The procedure is tested on the Columbia (USA) and Williams (Australia) Rivers, where ENSO influence has been well-documented, and then adopted on the unexplored Red River basin (Vietnam). Results show that IIS outcomes on the Columbia and Williams Rivers are consistent with the results of previous studies, and that ENSO indicators can be effectively used to enhance the streamflow forecast models capabilities. The experiments on the Red River basin show that the ENSO influence is less pronounced, inducing little effects on the basin hydro-meteorological processes.

  13. Intraclass Correlation Coefficients in Hierarchical Designs: Evaluation Using Latent Variable Modeling

    Science.gov (United States)

    Raykov, Tenko

    2011-01-01

    Interval estimation of intraclass correlation coefficients in hierarchical designs is discussed within a latent variable modeling framework. A method accomplishing this aim is outlined, which is applicable in two-level studies where participants (or generally lower-order units) are clustered within higher-order units. The procedure can also be…

  14. Laws of Large Numbers of Negatively Correlated Random Variables for Capacities

    Institute of Scientific and Technical Information of China (English)

    Wen-juan LI; Zeng-jing CHEN

    2011-01-01

    Our aim is to present some limit theorems for capacities.We consider a sequence of pairwise negatively correlated random variables.We obtain laws of large numbers for upper probabilities and 2-aiternating capacities,using some results in the classical probability theory and a non-additive version of Chebyshev's inequality and Borai-Contelli lemma for capacities.

  15. Determination of age and its correlation with biometric variables and seasonal reproductive indices of Leporinus obtusidens

    Directory of Open Access Journals (Sweden)

    Viviane de Oliveira Felizardo

    2015-07-01

    Full Text Available This study determined the age and its correlation with biometric variables and reproductive indices of piapara Leporinus obtusidens caught at the Funil Reservoir. We caught 133 specimens between September 2006 and August 2007. Weight, total length, standard length, depth, height, head length and radius of the scales were measured. The sex was determined by macroscopic examination of gonads. The age of each fish was determined by analyzing the growth rings on the scales. Seasonal differences in biometric variables were tested using the NK test at 5%. The correlation of age and radius of the scales with the biometric variables and reproductive indices were analyzed using the SAEG software. Fish individuals ranging from 3 to 14 years of age were caught. In the spring and summer, smaller fish were captured compared to those caught during the fall and winter. Females tended to have higher weight and morphometric values when compared to males. Age and radius of the scales were correlated with biometric variables in L. obtusidens. It can be concluded that the biometric variables of this species can be used as an indicator of age.

  16. The impacts of interannual climate variability and agricultural inputs on water footprint of crop production in an irrigation district of China.

    Science.gov (United States)

    Sun, Shikun; Wu, Pute; Wang, Yubao; Zhao, Xining; Liu, Jing; Zhang, Xiaohong

    2013-02-01

    Irrigation plays an increasing important role in agriculture of China. The assessment of water resources utilization during agricultural production process will contribute to improving agricultural water management practices for the irrigation districts. The water footprint provides a new approach to assessing the agricultural water utilization. The present paper put forward a modified calculation method to quantify the water footprint of crop. On this basis, this paper calculated the water footprint of major crop in Hetao irrigation district, China. Then, it evaluated the influencing factors that caused the variability of crop water footprint during the study period. Results showed that: 1) the annual average water footprint of integrated-crop production in Hetao irrigation district was 3.91 m(3)kg(-1) (90.91% blue water and 9.09% green water). The crop production in the Hetao irrigation district mainly relies on blue water; 2) under the integrated influences of interannual climate variability and variation of agricultural inputs, the water footprint of integrated-crop production displayed a decreasing trend; 3) the contribution rate of the climatic factors to the variation of water footprint was only -6.90%, while the total contribution rate of the agricultural inputs factors was -84.31%. The results suggest that the water footprint of crop mainly depends on agricultural management rather than the regional climate and its variation. The results indicated that the water footprint of a crop could be controlled at a reasonable level by better management of all agricultural inputs and the improvement of water use efficiency in agriculture. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Polishing tool and the resulting TIF for three variable machine parameters as input for the removal simulation

    Science.gov (United States)

    Schneider, Robert; Haberl, Alexander; Rascher, Rolf

    2017-06-01

    The trend in the optic industry shows, that it is increasingly important to be able to manufacture complex lens geometries on a high level of precision. From a certain limit on the required shape accuracy of optical workpieces, the processing is changed from the two-dimensional to point-shaped processing. It is very important that the process is as stable as possible during the in point-shaped processing. To ensure stability, usually only one process parameter is varied during processing. It is common that this parameter is the feed rate, which corresponds to the dwell time. In the research project ArenA-FOi (Application-oriented analysis of resource-saving and energy-efficient design of industrial facilities for the optical industry), a touching procedure is used in the point-attack, and in this case a close look is made as to whether a change of several process parameters is meaningful during a processing. The ADAPT tool in size R20 from Satisloh AG is used, which is also available for purchase. The behavior of the tool is tested under constant conditions in the MCP 250 CNC by OptoTech GmbH. A series of experiments should enable the TIF (tool influence function) to be determined using three variable parameters. Furthermore, the maximum error frequency that can be processed is calculated as an example for one parameter set and serves as an outlook for further investigations. The test results serve as the basic for the later removal simulation, which must be able to deal with a variable TIF. This topic has already been successfully implemented in another research project of the Institute for Precision Manufacturing and High-Frequency Technology (IPH) and thus this algorithm can be used. The next step is the useful implementation of the collected knowledge. The TIF must be selected on the basis of the measured data. It is important to know the error frequencies to select the optimal TIF. Thus, it is possible to compare the simulated results with real measurement

  18. Shannon information capacity of time reversal wideband multiple-input multiple-output system based on correlated statistical channels

    Science.gov (United States)

    Yu, Yang; Bing-Zhong, Wang; Shuai, Ding

    2016-05-01

    Utilizing channel reciprocity, time reversal (TR) technique increases the signal-to-noise ratio (SNR) at the receiver with very low transmitter complexity in complex multipath environment. Present research works about TR multiple-input multiple-output (MIMO) communication all focus on the system implementation and network building. The aim of this work is to analyze the influence of antenna coupling on the capacity of wideband TR MIMO system, which is a realistic question in designing a practical communication system. It turns out that antenna coupling stabilizes the capacity in a small variation range with statistical wideband channel response. Meanwhile, antenna coupling only causes a slight detriment to the channel capacity in a wideband TR MIMO system. Comparatively, uncorrelated stochastic channels without coupling exhibit a wider range of random capacity distribution which greatly depends on the statistical channel. The conclusions drawn from information difference entropy theory provide a guideline for designing better high-performance wideband TR MIMO communication systems. Project supported by the National Natural Science Foundation of China (Grant Nos. 61331007, 61361166008, and 61401065) and the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120185130001).

  19. Metabolic energy correlates of heart rate variability spectral power associated with a 900-calorie challenge.

    Science.gov (United States)

    Millis, Richard M; Austin, Rachel E; Hatcher, Mark D; Bond, Vernon; Goring, Kim L

    2011-01-01

    We studied healthy males challenged with a 900 Cal test beverage and correlated EE with the raw (ms(2)) and normalized units (nu) of total power (TP), low frequency/high frequency (LF/HF) and VLF spectral power of heart rate variability (HRV). The correlations were evaluated during 20 min of normal breathing (NB, control) and 20 min of paced breathing (PB) at 12 breaths·min(-1) (0.2 Hz). EE was not significantly correlated with any of the HRV variables before the metabolic challenge. After the challenge, EE was positively correlated with LF/HF and with VLF; VLF was also positively correlated with LF/HF during both NB and PB. These findings suggest that EE may be a correlate of LF/HF and of VLF spectral power of HRV in healthy adolescent/young adult males. The association of lower resting energy expenditure with lower amounts of VLF spectral power may occur in individuals with predilections for obese phenotypes.

  20. Metabolic Energy Correlates of Heart Rate Variability Spectral Power Associated with a 900-Calorie Challenge

    Directory of Open Access Journals (Sweden)

    Richard M. Millis

    2011-01-01

    Full Text Available We studied healthy males challenged with a 900 Cal test beverage and correlated EE with the raw (ms2 and normalized units (nu of total power (TP, low frequency/high frequency (LF/HF and VLF spectral power of heart rate variability (HRV. The correlations were evaluated during 20 min of normal breathing (NB, control and 20 min of paced breathing (PB at 12 breaths⋅min−1 (0.2 Hz. EE was not significantly correlated with any of the HRV variables before the metabolic challenge. After the challenge, EE was positively correlated with LF/HF and with VLF; VLF was also positively correlated with LF/HF during both NB and PB. These findings suggest that EE may be a correlate of LF/HF and of VLF spectral power of HRV in healthy adolescent/young adult males. The association of lower resting energy expenditure with lower amounts of VLF spectral power may occur in individuals with predilections for obese phenotypes.

  1. Biological correlates of blood pressure variability in elderly at high risk of cardiovascular disease.

    Science.gov (United States)

    Poortvliet, Rosalinde K E; Lloyd, Suzanne M; Ford, Ian; Sattar, Naveed; de Craen, Anton J M; Wijsman, Liselotte W; Mooijaart, Simon P; Westendorp, Rudi G J; Jukema, J Wouter; de Ruijter, Wouter; Gussekloo, Jacobijn; Stott, David J

    2015-04-01

    Visit-to-visit variability in blood pressure is an independent predictor of cardiovascular disease. This study investigates biological correlates of intra-individual variability in blood pressure in older persons. Nested observational study within the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) among 3,794 male and female participants (range 70-82 years) with a history of, or risk factors for cardiovascular disease. Individual visit-to-visit variability in systolic and diastolic blood pressure and pulse pressure (expressed as 1 SD in mm Hg) was assessed using nine measurements over 2 years. Correlates of higher visit-to-visit variability were examined at baseline, including markers of inflammation, endothelial function, renal function and glucose homeostasis. Over the first 2 years, the mean intra-individual variability (1 SD) was 14.4mm Hg for systolic blood pressure, 7.7mm Hg for diastolic blood pressure, and 12.6mm Hg for pulse pressure. After multivariate adjustment a higher level of interleukin-6 at baseline was consistently associated with higher intra-individual variability of blood pressure, including systolic, diastolic, and pulse pressure. Markers of endothelial function (Von Willebrand factor, tissue plasminogen activator), renal function (glomerular filtration rate) and glucose homeostasis (blood glucose, homeostatic model assessment index) were not or to a minor extent associated with blood pressure variability. In an elderly population at risk of cardiovascular disease, inflammation (as evidenced by higher levels of interleukin-6) is associated with higher intra-individual variability in systolic, diastolic, and pulse pressure. © American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Surface sediment diatoms from the western Pacific marginal seas and their correlation to environmental variables

    Institute of Scientific and Technical Information of China (English)

    HUANG Yue; JIANG Hui; Svante Bj(o)rck; LI Tiegang; LU Houyuan; RAN Lihua

    2009-01-01

    Diatom data of 192 surface sediment samples from the marginal seas in the western Pacific together with modern summer and winter sea surface temperature and salinity data were analyzed. The results of canonical correspondence analysis show that summer sea-surface salinity (SSS) is highly positively correlated with winter SSS and so is summer sea-surface temperature (SST) with winter SST. The correlations between SSSs and SSTs are less positively correlated, which may be due to interactions of regional current pattern and monsoon climate. The correlations between diatom species, sample sites and environmental variables concur with known diatom ecology and regional oceanographic characters. The results of forward selection of the environmental variables and associated Monte Carlo permutation tests of the statistical significance of each variable suggest that summer SSS and winter SST are the main environmental factors affecting the diatom distribution in the area and therefore preserved diatom data from down core could be used for reconstructions of summer SSS and winter SST in the region.

  3. Wavelet-based correlations of impedance cardiography signals and heart rate variability

    Science.gov (United States)

    Podtaev, Sergey; Dumler, Andrew; Stepanov, Rodion; Frick, Peter; Tziberkin, Kirill

    2010-04-01

    The wavelet-based correlation analysis is employed to study impedance cardiography signals (variation in the impedance of the thorax z(t) and time derivative of the thoracic impedance (- dz/dt)) and heart rate variability (HRV). A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. The modulus of wavelet-correlation function shows the level of correlation, and the phase indicates the mean phase shift of oscillations at the given scale (frequency). Significant correlations essentially exceeding the values obtained for noise signals are defined within two spectral ranges, which correspond to respiratory activity (0.14-0.5 Hz), endothelial related metabolic activity and neuroendocrine rhythms (0.0095-0.02 Hz). Probably, the phase shift of oscillations in all frequency ranges is related to the peculiarities of parasympathetic and neuro-humoral regulation of a cardiovascular system.

  4. Genetic variables of various manifestations of osteochondrosis and their correlations between and within joints in Dutch warmblood horses

    NARCIS (Netherlands)

    Grevenhof, van E.M.; Schurink, A.; Ducro, B.J.; Weeren, van P.R.; Tartwijk, van J.M.F.M.

    2009-01-01

    Osteochondrosis (OC) is an important orthopedic developmental disorder in many horse populations. A review of the literature revealed widely variable heritability estimates for the disorder. We estimated the genetic variables (heritabilities and genetic correlations) of various manifestations of OC.

  5. Diffusion tensor imaging of corpus callosum integrity in multiple sclerosis: correlation with disease variables.

    Science.gov (United States)

    Sigal, Tal; Shmuel, Miron; Mark, Dolev; Gil, Harari; Anat, Achiron

    2012-01-01

    Corpus callosum (CC) is frequently involved in multiple sclerosis (MS). We aimed to investigate the relations between CC microstructure integrity as measured by diffusion tensor imaging (DTI) in relapsing-remitting MS patients with low neurological disability in comparison with age-matched healthy subjects and further to identify correlations between DTI-CC parameters and clinical variables of MS disease activity. CC volume was measured on 3.0T brain MRI by MS Analyze software. DTI metrics acquired along 31 independent directions were obtained and fractional anisotropy (FA), apparent diffusion coefficient (ADC), longitudinal (λ1) and transverse (λ 2, λ 3) diffusivities were measured in MS patients and healthy subjects. Disease activity was assessed by relapse rate and neurolgical disability by the Extended Disability Status Scale (EDSS). Thirty relapsing-remitting MS patients and 30 age- and sex-matched healthy subjects were studied. CC volume and DTI metrics differed significantly between MS patients and healthy subjects. In MS patients, all DTI parameters correlated with neurological disability. ADC, longitudinal and transverse diffusivity correlated with disease duration. ADC and the transverse diffusivity correlated with relapse rate. CC DTI parameters, especially ADC and transverse diffusivity correlated with disease variables especially with those associated with clinical activity. Copyright © 2010 by the American Society of Neuroimaging.

  6. Suggestive correlations between the brightness of Neptune, solar variability, and Earth's temperature

    Science.gov (United States)

    Hammel, H. B.; Lockwood, G. W.

    2007-04-01

    Long-term photometric measurements of Neptune show variations of brightness over half a century. Seasonal change in Neptune's atmosphere may partially explain a general rise in the long-term light curve, but cannot explain its detailed variations. This leads us to consider the possibility of solar-driven changes, i.e., changes incurred by innate solar variability perhaps coupled with changing seasonal insolation. Although correlations between Neptune's brightness and Earth's temperature anomaly-and between Neptune and two models of solar variability-are visually compelling, at this time they are not statistically significant due to the limited degrees of freedom of the various time series. Nevertheless, the striking similarity of the temporal patterns of variation should not be ignored simply because of low formal statistical significance. If changing brightnesses and temperatures of two different planets are correlated, then some planetary climate changes may be due to variations in the solar system environment.

  7. Atrioventricular node and input pathways: a correlated gross anatomical and histological study of the canine atrioventricular junctional region.

    Science.gov (United States)

    Racker, D K

    1989-07-01

    To determine the architecture of the atrioventricular (AV) junctional region, structures in atrial preparations were correlated to those in serial sections made either parallel or perpendicular to the long axis of the AV node (AVN)/AV bundle complex. The results demonstrated the following for the first time: 1) A right medial atrial wall (MAW) extends anteriorly from the interatrial septum, superior to the interventricular septum (IVS). 2) An atrial interventricular septum (A-IVS) groove is located between the base of the MAW and the crest of the IVS. 3) Three atrionodal bundles converge to form a proximal AV bundle (PAVB), which in turn is contiguous with the AVN. The atrionodal bundles are associated with the MAW or the superomedial and inferolateral margins of the coronory sinus. Terminal portions of the atrionodal bundles and the PAVB reside within the A-IVS groove. The AV bundle was termed distal (DAVB) to avoid confusion. 4) The location of the AVN/DAVB complex topographically is deep to the apex of the septal cusp of the tricuspid valve subjacent to the MAW. Intracardially, the AVN/DAVB complex is within the central fibrous body. Significantly, this study resulted in the first unequivocal demonstration of discrete bundles of myocardial fibers associated with the atrial end of the AV node. Moreover, it appears likely that the atrionodal AV bundles are continuous with the sinoatrial nodal extensions, thereby forming internodal tracts.

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

    Directory of Open Access Journals (Sweden)

    Benjamin P Keck

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

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

    Science.gov (United States)

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

    2014-01-01

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

  10. Lagged Poincar\\'{e} and auto-correlation analysis of Heart rate variability in diabetes

    CERN Document Server

    Ghatak, S K

    2010-01-01

    The heart rate variability (HRV) in diabetic human subjects, has been analyzed using lagged Poincar\\'{e} plot, auto-correlation and the detrended fluctuation analysis methods. The parameters $SD1$, and $SD12 (= SD1/SD2)$ for Poincar\\'{e} plot for diabetic are lower than that for non-diabetic subjects and reverse is case for $SD2$ for all lagged number (m). The slope and the curvature of the plot SD12 vs m is much reduced for diabetic subject. The scatter plot of two successive interbeat intervals points out smaller variability in diabetic heart. The detrended fluctuation exponent has a higher value for diabetic group. The auto-correlation function of the deviation of interbeat interval in diabetic group shows highly correlated pattern when compared to that of normal one. The study suggests that the curvature of $SD12$ and auto-correlation method appear to be better way to assess the alteration of regulatory system on heart dynamics in diabetic condition.

  11. Modified Poisson-Nernst-Planck model with accurate Coulomb correlation in variable media

    CERN Document Server

    Liu, Pei; Xu, Zhenli

    2016-01-01

    We derive a set of modified Poisson-Nernst-Planck (PNP) equations for ion transport from the variation of the free energy functional which includes the many-body Coulomb correlation in media of variable dielectric coefficient. The correlation effects are considered through the Debye charging process in which the self energy of an ion is governed by the generalized Debye-H\\"uckel equation. We develop the asymptotic expansions of the self energy taking the ion radius as the small parameter such that the multiscale model can be solved efficiently by numerical methods. We show that the variations of the energy functional give the self-energy-modified PNP equations which satisfy a proper energy law. We present the numerical results from different asymptotic expansions with a semi-implicit conservative numerical method and investigate the effect of the Coulomb correlation.

  12. Multiple linear regression with correlations among the predictor variables. Theory and computer algorithm ridge (FORTRAN 77)

    Science.gov (United States)

    van Gaans, P. F. M.; Vriend, S. P.

    Application of ridge regression in geoscience usually is a more appropriate technique than ordinary least-squares regression, especially in the situation of highly intercorrelated predictor variables. A FORTRAN 77 program RIDGE for ridged multiple linear regression is presented. The theory of linear regression and ridge regression is treated, to allow for a careful interpretation of the results and to understand the structure of the program. The program gives various parameters to evaluate the extent of multicollinearity within a given regression problem, such as the correlation matrix, multiple correlations among the predictors, variance inflation factors, eigenvalues, condition number, and the determinant of the predictors correlation matrix. The best method for the optimum choice of the ridge parameter with ridge regression has not been established yet. Estimates of the ridge bias, ridged variance inflation factors, estimates, and norms for the ridge parameter therefore are given as output by RIDGE and should complement inspection of the ridge traces. Application within the earth sciences is discussed.

  13. Harmonize input selection for sediment transport prediction

    Science.gov (United States)

    Afan, Haitham Abdulmohsin; Keshtegar, Behrooz; Mohtar, Wan Hanna Melini Wan; El-Shafie, Ahmed

    2017-09-01

    In this paper, three modeling approaches using a Neural Network (NN), Response Surface Method (RSM) and response surface method basis Global Harmony Search (GHS) are applied to predict the daily time series suspended sediment load. Generally, the input variables for forecasting the suspended sediment load are manually selected based on the maximum correlations of input variables in the modeling approaches based on NN and RSM. The RSM is improved to select the input variables by using the errors terms of training data based on the GHS, namely as response surface method and global harmony search (RSM-GHS) modeling method. The second-order polynomial function with cross terms is applied to calibrate the time series suspended sediment load with three, four and five input variables in the proposed RSM-GHS. The linear, square and cross corrections of twenty input variables of antecedent values of suspended sediment load and water discharge are investigated to achieve the best predictions of the RSM based on the GHS method. The performances of the NN, RSM and proposed RSM-GHS including both accuracy and simplicity are compared through several comparative predicted and error statistics. The results illustrated that the proposed RSM-GHS is as uncomplicated as the RSM but performed better, where fewer errors and better correlation was observed (R = 0.95, MAE = 18.09 (ton/day), RMSE = 25.16 (ton/day)) compared to the ANN (R = 0.91, MAE = 20.17 (ton/day), RMSE = 33.09 (ton/day)) and RSM (R = 0.91, MAE = 20.06 (ton/day), RMSE = 31.92 (ton/day)) for all types of input variables.

  14. The correlation of dawn phenomenon with glycemic variability parameters in type 2 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Roman Gabriela

    2016-03-01

    Full Text Available Introduction. Dawn phenomenon could have deleterious effect on overall glycemic control. Glycemic variability may be an independent risk factor for the development of diabetes chronic complications. The study aimed to evaluate any correlations between the dawn phenomenon and parameters of glycemic variability in a cohort of type 2 diabetes patients (T2DM. Material and methods. This retrospective observational study included 131 T2DM patients. Continuous glucose monitoring (CGM has been performed. Data from the first 24h of full recording were used for analysis of glycemic variability indices: mean level of 24h interstitial glucose value and standard deviation; % coefficient of variation; J index; mean amplitude of glycemic excursion - MAGE; continuous overall net glycemic action (CONGA at 1, 2, 4 and 6 hours; mean of daily differences (MODD index. Results. Mean age was 56.04 ± 9.91 years, 35.9% women, 17.6% on diet, 53.4% on oral therapy and 29% on insulin. Dawn phenomenon was more frequent in patients below 60 years (70% and in oral therapy group (72.85%. Significant correlations between the dawn phenomenon and j-index, MAGE, CONGA-4 and CONGA-6 have been found in T2DM patients on diet therapy alone. The amplitude of dawn phenomenon was 46.10 ± 24.40 mg/dl and significantly correlated (p<0.05 after adjustment for age, gender and treatment with % CV, MAGE, CONGA-1, CONGA-2, CONGA-4, CONGA-6 and MODD. Conclusions. The dawn phenomenon significantly increases the glycemic variability parameters in drug-naive T2DM patients, with no impact in T2DM on oral or insulin therapy.

  15. Evaluation of dual-input perfusion in lung cancer using a 320-detector CT: Its correlation with tumor size, location, and presence of metastasis

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Eun Ju; Lee, Ki Nam; Roh, Mee Sook; Son, Choon Hee [Dong-A University College of Medicine, Busan (Korea, Republic of); Roh, Mee Sook [Dept. of Radiology, Dongnam Institute of Radiological and Medical Sciences, Busan (Korea, Republic of)

    2016-11-15

    The purposes of our study were to assess the dual blood supply of lung cancer using a computed tomography (CT) perfusion technique, and to analyze the correlations between dual perfusion and various characteristics of lung cancer. Thirty-five consecutive patients with lung tumors highly suggestive of malignancy were included in this study. All subjects underwent a dual-input dynamic perfusion volume scan using a 320-detector-row CT before CT-guided biopsy. The pulmonary trunk and the descending thoracic aorta were selected for the arterial input functions. From the CT data, pulmonary arterial perfusion (PP), aortic perfusion (AP), and the perfusion index [PI = PP / (PP + AP)] were calculated using the dual-input maximum-slope method. We statistically analyzed the relationship of the perfusion data with tumor locations (central, peripheral, and abutting the pleural lesions), tumor volumes, and the presence of lymph node metastasis or distant metastasis. All subjects were pathologically diagnosed with primary lung cancers via CT-guided aspiration biopsy. The overall mean PI was 53.7 ± 7.2%. The PI showed a significant difference according to the tumor location (central, 49.2 ± 3.3%; peripheral, 56.2 ± 6.7%; abutting the pleural lesions, 48.9 ± 7.6%, p = 0.047). In contrast, no significant difference was detected in tumor size or the presence of metastasis (p > 0.05). We found that the proportion of dual perfusion in lung cancer was significantly dependent on the location of the tumor, while tumor size or the presence of metastasis was not distinctly associated with dual perfusion.

  16. Global O3-CO correlations in a chemistry and transport model during July-August: evaluation with TES satellite observations and sensitivity to input meteorological data and emissions

    Science.gov (United States)

    Choi, Hyun-Deok; Liu, Hongyu; Crawford, James H.; Considine, David B.; Allen, Dale J.; Duncan, Bryan N.; Horowitz, Larry W.; Rodriguez, Jose M.; Strahan, Susan E.; Zhang, Lin; Liu, Xiong; Damon, Megan R.; Steenrod, Stephen D.

    2017-07-01

    We examine the capability of the Global Modeling Initiative (GMI) chemistry and transport model to reproduce global mid-tropospheric (618 hPa) ozone-carbon monoxide (O3-CO) correlations determined by the measurements from the Tropospheric Emission Spectrometer (TES) aboard NASA's Aura satellite during boreal summer (July-August). The model is driven by three meteorological data sets (finite-volume General Circulation Model (fvGCM) with sea surface temperature for 1995, Goddard Earth Observing System Data Assimilation System Version 4 (GEOS-4 DAS) for 2005, and Modern-Era Retrospective Analysis for Research and Applications (MERRA) for 2005), allowing us to examine the sensitivity of model O3-CO correlations to input meteorological data. Model simulations of radionuclide tracers (222Rn, 210Pb, and 7Be) are used to illustrate the differences in transport-related processes among the meteorological data sets. Simulated O3 values are evaluated with climatological profiles from ozonesonde measurements and satellite tropospheric O3 columns. Despite the fact that the three simulations show significantly different global and regional distributions of O3 and CO concentrations, they show similar patterns of O3-CO correlations on a global scale. All model simulations sampled along the TES orbit track capture the observed positive O3-CO correlations in the Northern Hemisphere midlatitude continental outflow and the Southern Hemisphere subtropics. While all simulations show strong negative correlations over the Tibetan Plateau, northern Africa, the subtropical eastern North Pacific, and the Caribbean, TES O3 and CO concentrations at 618 hPa only show weak negative correlations over much narrower areas (i.e., the Tibetan Plateau and northern Africa). Discrepancies in regional O3-CO correlation patterns in the three simulations may be attributed to differences in convective transport, stratospheric influence, and subsidence, among other processes. To understand how various

  17. High resolution variability in the Quaternary Indian monsoon inferred from records of clastic input and paleo-production recovered during IODP Expedition 355

    Science.gov (United States)

    Hahn, Annette; Lyle, Mitchell; Kulhanek, Denise; Ando, Sergio; Clift, Peter

    2016-04-01

    The sediment cores obtained from the Indus fan at Site U1457 during Expedition 355 of the International Ocean Discovery Program (IODP) contain a ca. 100m spliced section covering the past ca. 1Ma. We aim to make use of this unique long, mostly continuous climate archive to unravel the millennial scale atmospheric and oceanic processes linked to changes in the Indian monsoon climate over the Quaternary glacial-interglacial cycles. Our aim is to fill this gap using fast, cost-efficient methods (Fourier Transform Infrared Spectroscopy [FTIRS] and X-ray Fluorescence [XRF] scanning) which allow us to study this sequence at a millennial scale resolution (2-3cm sampling interval). An important methodological aspect of this study is developing FTIRS as a method for the simultaneous estimation of the sediment total inorganic carbon and organic carbon content by using the specific fingerprint absorption spectra of minerals (e.g. calcite) and organic sediment components. The resulting paleo-production proxies give indications of oceanic circulation patterns and serve as a direct comparison to the XRF scanning data. Initial results show that variability in paleo-production is accompanied by changes in the quantity and composition of clastic input to the site. Phases of increased deposition of terrigenous material are enriched in K, Al, Fe and Si. Both changes in the weathering and erosion focus areas affect the mineralogy and elemental composition of the clastic input as grain size and mineralogical changes are reflected in the ratios of lighter to heavier elements. Furthermore, trace element compositions (Zn, Cu, Mn) give indications of diagenetic processes and contribute to the understanding of the depositional environment. The resulting datasets will lead to a more comprehensive understanding of the interplay of the local atmospheric and oceanic circulation processes over glacial-interglacial cycles; an essential prerequisite for regional predictions of global climate

  18. Heart Rate Variability Correlates to Functional Aerobic Impairment in Hemodialysis Patients

    Directory of Open Access Journals (Sweden)

    Maria Angela Magalhães de Queiroz Carreira

    2015-06-01

    Full Text Available Background: Autonomic dysfunction (AD is highly prevalent in hemodialysis (HD patients and has been implicated in their increased risk of cardiovascular mortality. Objective: To correlate heart rate variability (HRV during exercise treadmill test (ETT with the values obtained when measuring functional aerobic impairment (FAI in HD patients and controls. Methods: Cross-sectional study involving HD patients and a control group. Clinical examination, blood sampling, transthoracic echocardiogram, 24-hour Holter, and ETT were performed. A symptom-limited ramp treadmill protocol with active recovery was employed. Heart rate variability was evaluated in time domain at exercise and recovery periods. Results: Forty-one HD patients and 41 controls concluded the study. HD patients had higher FAI and lower HRV than controls (p<0.001 for both. A correlation was found between exercise HRV (SDNN and FAI in both groups. This association was independent of age, sex, smoking, body mass index, diabetes, and clonidine or beta-blocker use, but not of hemoglobin levels. Conclusion: No association was found between FAI and HRV on 24-hour Holter or at the recovery period of ETT. Of note, exercise HRV was inversely correlated with FAI in HD patients and controls. (Arq Bras Cardiol. 2015; [online]. ahead print, PP.0-0

  19. Motor skills in kindergarten: Internal structure, cognitive correlates and relationships to background variables.

    Science.gov (United States)

    Oberer, Nicole; Gashaj, Venera; Roebers, Claudia M

    2017-04-01

    The present study aimed to contribute to the discussion about the relation between motor coordination and executive functions in preschool children. Specifically, the relation between gross and fine motor skills and executive functions as well as the relation to possible background variables (SES, physical activity) were investigated. Based on the data of N=156 kindergarten children the internal structure of motor skills was investigated and confirmed the theoretically assumed subdivision of gross and fine motor skills. Both, gross and fine motor skills correlated significantly with executive functions, whereas the background variables seemed to have no significant impact on the executive functions and motor skills. Higher order control processes are discussed as an explanation of the relation between executive functions and motor skills. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Workhardening correlations based on state variables in some FCC metals in monotonic loading

    Science.gov (United States)

    Korhonen, M. A.; Hannula, S.-P.; Li, Che-Yu

    1985-03-01

    This paper reports an investigation of the workhardening properties of 316 stainless steel, commercial purity aluminum, and OFHC copper at room temperature by using a state-variable approach. Based on the results of experiments, it is proposed that a generalized workhardening correlation can be formulated by using two state variables only, the structural state parameter and the inelastic strain rate. Particularly, an absolute workhardening coefficient is proposed to be a product of two parts. The athermal part, which is structure dependent only, will be approached at low homologous temperatures and/or high strain rates, while the strain rate sensitive part describes a dynamic recovery contribution at high homologous temperatures and/or low strain rates. Correspondingly, based on this approach a new way of separating thermal and athermal contributions to workhardening rate are suggested. Moreover, it is shown that a single master curve can be constructed to display the dependence of workhardening coefficient on structure and strain rate.

  1. Workhardening correlations based on state variables in some FCC metals in monotonic loadings

    Energy Technology Data Exchange (ETDEWEB)

    Korhonen, M.A.; Hannula, S.P.; Li, C.Y.

    1983-10-01

    This paper reports an investigation based on a state variable approach of workhardening properties of 316 stainless steel, commercial purity aluminium and OFHC copper at room temperature. It is proposed that a generalized workhardening correlation can be formulated by using two state variables only, the structural state parameter and the inelastic strain rate. Particularly, an absolute workhardening coefficient is proposed to be a product of two parts: the athermal part, which is structure dependent only, will be approached at low homologous temperatures and/or high strain rates, while the strain rate sensitive part describes a dynamic recovery contribution at high homologous temperatures and/or low strain rates. Moreover, it is shown that a single master curve can be constructed to display the dependence of workhardening coefficient on structure and strain rate.

  2. Enhancing the comparability of costing methods: cross-country variability in the prices of non-traded inputs to health programmes

    Directory of Open Access Journals (Sweden)

    Evans David B

    2006-04-01

    Full Text Available Abstract Background National and international policy makers have been increasing their focus on developing strategies to enable poor countries achieve the millennium development goals. This requires information on the costs of different types of health interventions and the resources needed to scale them up, either singly or in combinations. Cost data also guides decisions about the most appropriate mix of interventions in different settings, in view of the increasing, but still limited, resources available to improve health. Many cost and cost-effectiveness studies include only the costs incurred at the point of delivery to beneficiaries, omitting those incurred at other levels of the system such as administration, media, training and overall management. The few studies that have measured them directly suggest that they can sometimes account for a substantial proportion of total costs, so that their omission can result in biased estimates of the resources needed to run a programme or the relative cost-effectiveness of different choices. However, prices of different inputs used in the production of health interventions can vary substantially within a country. Basing cost estimates on a single price observation runs the risk that the results are based on an outlier observation rather than the typical costs of the input. Methods We first explore the determinants of the observed variation in the prices of selected "non-traded" intermediate inputs to health programmes – printed matter and media advertising, and water and electricity – accounting for variation within and across countries. We then use the estimated relationship to impute average prices for countries where limited data are available with uncertainty intervals. Results Prices vary across countries with GDP per capita and a number of determinants of supply and demand. Media and printing were inelastic with respect to GDP per capita, with a positive correlation, while the utilities

  3. Pearson's Correlation between Three Variables; Using Students' Basic Knowledge of Geometry for an Exercise in Mathematical Statistics

    Science.gov (United States)

    Vos, Pauline

    2009-01-01

    When studying correlations, how do the three bivariate correlation coefficients between three variables relate? After transforming Pearson's correlation coefficient r into a Euclidean distance, undergraduate students can tackle this problem using their secondary school knowledge of geometry (Pythagoras' theorem and similarity of triangles).…

  4. Predicting the Energy Output of Wind Farms Based on Weather Data: Important Variables and their Correlation

    CERN Document Server

    Vladislavleva, Katya; Neumann, Frank; Wagner, Markus

    2011-01-01

    Wind energy plays an increasing role in the supply of energy world-wide. The energy output of a wind farm is highly dependent on the weather condition present at the wind farm. If the output can be predicted more accurately, energy suppliers can coordinate the collaborative production of different energy sources more efficiently to avoid costly overproductions. With this paper, we take a computer science perspective on energy prediction based on weather data and analyze the important parameters as well as their correlation on the energy output. To deal with the interaction of the different parameters we use symbolic regression based on the genetic programming tool DataModeler. Our studies are carried out on publicly available weather and energy data for a wind farm in Australia. We reveal the correlation of the different variables for the energy output. The model obtained for energy prediction gives a very reliable prediction of the energy output for newly given weather data.

  5. Spatio-temporal variability of airborne bacterial communities and their correlation with particulate matter chemical composition across two urban areas.

    Science.gov (United States)

    Gandolfi, I; Bertolini, V; Bestetti, G; Ambrosini, R; Innocente, E; Rampazzo, G; Papacchini, M; Franzetti, A

    2015-06-01

    The study of spatio-temporal variability of airborne bacterial communities has recently gained importance due to the evidence that airborne bacteria are involved in atmospheric processes and can affect human health. In this work, we described the structure of airborne microbial communities in two urban areas (Milan and Venice, Northern Italy) through the sequencing, by the Illumina platform, of libraries containing the V5-V6 hypervariable regions of the 16S rRNA gene and estimated the abundance of airborne bacteria with quantitative PCR (qPCR). Airborne microbial communities were dominated by few taxa, particularly Burkholderiales and Actinomycetales, more abundant in colder seasons, and Chloroplasts, more abundant in warmer seasons. By partitioning the variation in bacterial community structure, we could assess that environmental and meteorological conditions, including variability between cities and seasons, were the major determinants of the observed variation in bacterial community structure, while chemical composition of atmospheric particulate matter (PM) had a minor contribution. Particularly, Ba, SO4 (2-) and Mg(2+) concentrations were significantly correlated with microbial community structure, but it was not possible to assess whether they simply co-varied with seasonal shifts of bacterial inputs to the atmosphere, or their variation favoured specific taxa. Both local sources of bacteria and atmospheric dispersal were involved in the assembling of airborne microbial communities, as suggested, to the one side by the large abundance of bacteria typical of lagoon environments (Rhodobacterales) observed in spring air samples from Venice and to the other by the significant effect of wind speed in shaping airborne bacterial communities at all sites.

  6. Correlations between dentoskeletal variables and deep bite in Class II Division 1 individuals

    Directory of Open Access Journals (Sweden)

    Leandro Silva Marques

    2011-02-01

    Full Text Available This study aimed to evaluate the cephalometric pattern of Class II Division 1 individuals with deep bite, and to determine possible correlations between dentoskeletal variables and deep bite. Comparisons were also made between genders and cases that were to be treated both with and without premolar extraction. A total of 70 lateral cephalograms were used, from both male (n = 35 and female (n = 35 individuals with an average age of 11.6 years, who simultaneously presented with ANB > 5º and overbite > 4 mm. Statistical analysis involved parametric (t-test and non-parametric (Mann-Whitney tests for independent samples, as well as the Spearman correlation test (p < 0.05. The values of Go-Me, Ar-Pog, PM-1 and PM-CMI were higher in males (p < 0.05. However, no significant differences were found among the averages of the cephalometric measurements when the sample was divided by treatment with and without extraction. Deep bite was positively correlated to the PM-1 and SNA measurements, and negatively correlated to the Go-Me, Ar-Pog, SNB and SNGoMe measurements. The main factors associated with the determination of deep bite in Angle's Class II Division 1 cases were: greater lower anterior dentoalveolar growth and/or lower incisor extrusion, horizontal growth pattern, maxillary protrusion and mandibular retrusion.

  7. Forecasting Urban Water Demand via Machine Learning Methods Coupled with a Bootstrap Rank-Ordered Conditional Mutual Information Input Variable Selection Method

    Science.gov (United States)

    Adamowski, J. F.; Quilty, J.; Khalil, B.; Rathinasamy, M.

    2014-12-01

    This paper explores forecasting short-term urban water demand (UWD) (using only historical records) through a variety of machine learning techniques coupled with a novel input variable selection (IVS) procedure. The proposed IVS technique termed, bootstrap rank-ordered conditional mutual information for real-valued signals (brCMIr), is multivariate, nonlinear, nonparametric, and probabilistic. The brCMIr method was tested in a case study using water demand time series for two urban water supply system pressure zones in Ottawa, Canada to select the most important historical records for use with each machine learning technique in order to generate forecasts of average and peak UWD for the respective pressure zones at lead times of 1, 3, and 7 days ahead. All lead time forecasts are computed using Artificial Neural Networks (ANN) as the base model, and are compared with Least Squares Support Vector Regression (LSSVR), as well as a novel machine learning method for UWD forecasting: the Extreme Learning Machine (ELM). Results from one-way analysis of variance (ANOVA) and Tukey Honesty Significance Difference (HSD) tests indicate that the LSSVR and ELM models are the best machine learning techniques to pair with brCMIr. However, ELM has significant computational advantages over LSSVR (and ANN) and provides a new and promising technique to explore in UWD forecasting.

  8. Correlating novel variable and conserved motifs in the Hemagglutinin protein with significant biological functions

    Directory of Open Access Journals (Sweden)

    Werner Mark

    2008-08-01

    Full Text Available Abstract Background Variations in the influenza Hemagglutinin protein contributes to antigenic drift resulting in decreased efficiency of seasonal influenza vaccines and escape from host immune response. We performed an in silico study to determine characteristics of novel variable and conserved motifs in the Hemagglutinin protein from previously reported H3N2 strains isolated from Hong Kong from 1968–1999 to predict viral motifs involved in significant biological functions. Results 14 MEME blocks were generated and comparative analysis of the MEME blocks identified blocks 1, 2, 3 and 7 to correlate with several biological functions. Analysis of the different Hemagglutinin sequences elucidated that the single block 7 has the highest frequency of amino acid substitution and the highest number of co-mutating pairs. MEME 2 showed intermediate variability and MEME 1 was the most conserved. Interestingly, MEME blocks 2 and 7 had the highest incidence of potential post-translational modifications sites including phosphorylation sites, ASN glycosylation motifs and N-myristylation sites. Similarly, these 2 blocks overlap with previously identified antigenic sites and receptor binding sites. Conclusion Our study identifies motifs in the Hemagglutinin protein with different amino acid substitution frequencies over a 31 years period, and derives relevant functional characteristics by correlation of these motifs with potential post-translational modifications sites, antigenic and receptor binding sites.

  9. Correlating novel variable and conserved motifs in the Hemagglutinin protein with significant biological functions

    Science.gov (United States)

    Gendoo, Deena MA; El-Hefnawi, Mahmoud M; Werner, Mark; Siam, Rania

    2008-01-01

    Background Variations in the influenza Hemagglutinin protein contributes to antigenic drift resulting in decreased efficiency of seasonal influenza vaccines and escape from host immune response. We performed an in silico study to determine characteristics of novel variable and conserved motifs in the Hemagglutinin protein from previously reported H3N2 strains isolated from Hong Kong from 1968–1999 to predict viral motifs involved in significant biological functions. Results 14 MEME blocks were generated and comparative analysis of the MEME blocks identified blocks 1, 2, 3 and 7 to correlate with several biological functions. Analysis of the different Hemagglutinin sequences elucidated that the single block 7 has the highest frequency of amino acid substitution and the highest number of co-mutating pairs. MEME 2 showed intermediate variability and MEME 1 was the most conserved. Interestingly, MEME blocks 2 and 7 had the highest incidence of potential post-translational modifications sites including phosphorylation sites, ASN glycosylation motifs and N-myristylation sites. Similarly, these 2 blocks overlap with previously identified antigenic sites and receptor binding sites. Conclusion Our study identifies motifs in the Hemagglutinin protein with different amino acid substitution frequencies over a 31 years period, and derives relevant functional characteristics by correlation of these motifs with potential post-translational modifications sites, antigenic and receptor binding sites. PMID:18681973

  10. Correlation structure and variable selection in generalized estimating equations via composite likelihood information criteria.

    Science.gov (United States)

    Nikoloulopoulos, Aristidis K

    2016-06-30

    The method of generalized estimating equations (GEE) is popular in the biostatistics literature for analyzing longitudinal binary and count data. It assumes a generalized linear model for the outcome variable, and a working correlation among repeated measurements. In this paper, we introduce a viable competitor: the weighted scores method for generalized linear model margins. We weight the univariate score equations using a working discretized multivariate normal model that is a proper multivariate model. Because the weighted scores method is a parametric method based on likelihood, we propose composite likelihood information criteria as an intermediate step for model selection. The same criteria can be used for both correlation structure and variable selection. Simulations studies and the application example show that our method outperforms other existing model selection methods in GEE. From the example, it can be seen that our methods not only improve on GEE in terms of interpretability and efficiency but also can change the inferential conclusions with respect to GEE. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Anti-correlated Optical Flux and Polarization Variability in BL Lac

    CERN Document Server

    Gaur, Haritma; Wiita, Paul J; Uemura, Makoto; Itoh, Ryosuke; Sasada, Mahito

    2013-01-01

    We present the results of photometric (V band) and polarimetric observations of the blazar BL Lac during 2008--2010 using TRISPEC attached to the KANATA 1.5-m telescope in Japan. The data reveal a great deal of variability ranging from days to months with detection of strong variations in fractional polarization. The V band flux strongly anti-correlates with the degree of polarization during the first of two observing seasons but not during the second. The direction of the electric vector, however, remained roughly constant during all our observations. These results are consistent with a model with at least two emission regions being present, with the more variable component having a polarization direction nearly perpendicular to that of the relatively quiescent region so that a rising flux can produce a decline in degree of polarization. We also computed models involving helical jet structures and single transverse shocks in jets and show that they might also be able to agree with the anti-correlations betwe...

  12. Correlation between glycemic variability and gastroesophageal reflux in adolescentswith type 1 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    I L Alimova

    2013-03-01

    Full Text Available Aims. To estimate an impact of glycemic variability on the development of gastroesophageal reflux disease (GERD in adolescents with type 1 diabetes mellitus (T1DM.Materials and methods. We enrolled 33 patients with T1DM aged from 12 to 17 years. 24-h pH-monitoring was performed with “Gas- troskan 24” system (Istok-Sistema, Fryazino; 24-h continuous glucose monitoring utilized CGMS MMT-7310 (Medtronic Minimed, USA with subsequent night-time analysis.Results. As compared to stable night-time glycemia controls (SD <2.0 mmol/L, patients with higher night-time glycemic variability (SD>2.0 mmol/L showed longer period of esophageal acidification (17% [2–58]; p<0.001, higher incidence of acid reflux events with duration above 5 min (2 ev. [1-10]; p<0.001, longer period of most protracted acid reflux event (63 min [5–132]; p<0.001, as well as higher prevalence of pathologic acid GER events (76.4%; χ2=17.11; p<0.001 during night-time. Increase in glycemic in- stability positively correlated with incidence and severity of acid GER events. 6-8 months follow-up supported these findings. Conclusion. Glycemic variability in adolescents with T1DM is a significant risk factor for development of GERD with hypomotor dys- function according to pH-monitoring.

  13. COPD phenotypes on computed tomography and its correlation with selected lung function variables in severe patients

    Directory of Open Access Journals (Sweden)

    da Silva SMD

    2016-03-01

    Full Text Available Silvia Maria Doria da Silva, Ilma Aparecida Paschoal, Eduardo Mello De Capitani, Marcos Mello Moreira, Luciana Campanatti Palhares, Mônica Corso PereiraPneumology Service, Department of Internal Medicine, School of Medical Sciences, State University of Campinas (UNICAMP, Campinas, São Paulo, BrazilBackground: Computed tomography (CT phenotypic characterization helps in understanding the clinical diversity of chronic obstructive pulmonary disease (COPD patients, but its clinical relevance and its relationship with functional features are not clarified. Volumetric capnography (VC uses the principle of gas washout and analyzes the pattern of CO2 elimination as a function of expired volume. The main variables analyzed were end-tidal concentration of carbon dioxide (ETCO2, Slope of phase 2 (Slp2, and Slope of phase 3 (Slp3 of capnogram, the curve which represents the total amount of CO2 eliminated by the lungs during each breath.Objective: To investigate, in a group of patients with severe COPD, if the phenotypic analysis by CT could identify different subsets of patients, and if there was an association of CT findings and functional variables.Subjects and methods: Sixty-five patients with COPD Gold III–IV were admitted for clinical evaluation, high-resolution CT, and functional evaluation (spirometry, 6-minute walk test [6MWT], and VC. The presence and profusion of tomography findings were evaluated, and later, the patients were identified as having emphysema (EMP or airway disease (AWD phenotype. EMP and AWD groups were compared; tomography findings scores were evaluated versus spirometric, 6MWT, and VC variables.Results: Bronchiectasis was found in 33.8% and peribronchial thickening in 69.2% of the 65 patients. Structural findings of airways had no significant correlation with spirometric variables. Air trapping and EMP were strongly correlated with VC variables, but in opposite directions. There was some overlap between the EMP and AWD

  14. Study on phylogenetic relationships, variability, and correlated mutations in M2 proteins of influenza virus A.

    Directory of Open Access Journals (Sweden)

    Ly Le

    Full Text Available M2 channel, an influenza virus transmembrane protein, serves as an important target for antiviral drug design. There are still discordances concerning the role of some residues involved in proton transfer as well as the mechanism of inhibition by commercial drugs. The viral M2 proteins show high conservativity; about 3/4 of the positions are occupied by one residue in over 95%. Nine M2 proteins from the H3N2 strain and possibly two proteins from H2N2 strains make a phylogenic cluster closely related to 2RLF. The variability range is limited to 4 residues/position with one exception. The 2RLF protein stands out by the presence of 2 serines at the positions 19 and 50, which are in most other M2 proteins occupied by cysteines. The study of correlated mutations shows that there are several positions with significant mutational correlation that have not been described so far as functionally important. That there are 5 more residues potentially involved in the M2 mechanism of action. The original software used in this work (Consensus Constructor, SSSSg, Corm, Talana is freely accessible as stand-alone offline applications upon request to the authors. The other software used in this work is freely available online for noncommercial purposes at public services on bioinformatics such as ExPASy or NCBI. The study on mutational variability, evolutionary relationship, and correlated mutation presented in this paper is a potential way to explain more completely the role of significant factors in proton channel action and to clarify the inhibition mechanism by specific drugs.

  15. Statistical correlation of fractional oscillator response by complex spectral moments and state variable expansion

    Science.gov (United States)

    Pinnola, Francesco Paolo

    2016-10-01

    The statistical characterization of the oscillator response with non-integer order damping under Gaussian noise represents an important challenge in the modern stochastic mechanics. In fact, this kind of problem appears in several issues of different type (wave propagation in viscoelastic media, Brownian motion, fluid dynamics, RLC circuit, etc.). The aim of this paper is to provide a stochastic characterization of the stationary response of linear fractional oscillator forced by normal white noise. In particular, this paper shows a new method to obtain the correlation function by exact complex spectral moments. These complex quantities contain all the information to describe the random processes but in the considered case their analytical evaluation needs some mathematical manipulations. For this reason such complex spectral moment characterization is used in conjunction with a fractional-order state variable analysis. This kind of analysis permits to find the exact expression of complex spectral moments, and the correlation function by using the Mellin transform. Moreover, the proposed approach provides an analytical expression of the response variance of the fractional oscillator. Capability and efficiency of the present method are shown in the numerical examples in which correlation and variance of fractional oscillator response are found and compared with those obtained by Monte Carlo simulations.

  16. Personality Traits and Socio-Demographic Variables as Correlates of Counselling Effectiveness of Counsellors in Enugu State, Nigeria

    Science.gov (United States)

    Onyekuru, Bruno U.; Ibegbunam, Josephat

    2015-01-01

    Quality personality traits and socio-demographic variables are essential elements of effective counselling. This correlational study investigated personality traits and socio-demographic variables as predictors of counselling effectiveness of counsellors in Enugu State. The instruments for data collection were Personality Traits Assessment Scale…

  17. Intraclass Correlation Coefficients in Hierarchical Design Studies with Discrete Response Variables: A Note on a Direct Interval Estimation Procedure

    Science.gov (United States)

    Raykov, Tenko; Marcoulides, George A.

    2015-01-01

    A latent variable modeling procedure that can be used to evaluate intraclass correlation coefficients in two-level settings with discrete response variables is discussed. The approach is readily applied when the purpose is to furnish confidence intervals at prespecified confidence levels for these coefficients in setups with binary or ordinal…

  18. Correlative changes in life-history variables in response to environmental change in a model organism.

    Science.gov (United States)

    Smallegange, Isabel M; Deere, Jacques A; Coulson, Tim

    2014-06-01

    Global change alters the environment, including increases in the frequency of (un)favorable events and shifts in environmental noise color. However, how these changes impact the dynamics of populations, and whether these can be predicted accurately has been largely unexamined. Here we combine recently developed population modeling approaches and theory in stochastic demography to explore how life history, morphology, and average fitness respond to changes in the frequency of favorable environmental conditions and in the color of environmental noise in a model organism (an acarid mite). We predict that different life-history variables respond correlatively to changes in the environment, and we identify different life-history variables, including lifetime reproductive success, as indicators of average fitness and life-history speed across stochastic environments. Depending on the shape of adult survival rate, generation time can be used as an indicator of the response of populations to stochastic change, as in the deterministic case. This work is a useful step toward understanding population dynamics in stochastic environments, including how stochastic change may shape the evolution of life histories.

  19. The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Babic, A; Bangale, P; de Almeida, U Barres; Barrio, J A; González, J Becerra; Bednarek, W; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bock, R K; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T

    2015-01-01

    We performed a 4.5-month multi-instrument campaign (from radio to VHE gamma rays) on Mrk421 between January 2009 and June 2009, which included VLBA, F-GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, and Whipple, among other instruments and collaborations. Mrk421 was found in its typical (non-flaring) activity state, with a VHE flux of about half that of the Crab Nebula, yet the light curves show significant variability at all wavelengths, the highest variability being in the X-rays. We determined the power spectral densities (PSD) at most wavelengths and found that all PSDs can be described by power-laws without a break, and with indices consistent with pink/red-noise behavior. We observed a harder-when-brighter behavior in the X-ray spectra and measured a positive correlation between VHE and X-ray fluxes with zero time lag. Such characteristics have been reported many times during flaring activity, but here they are reported for the first time in the non-flaring state. We also observed an overall anti-corre...

  20. A Black Hole Mass-Variability Time Scale Correlation at Submillimeter Wavelengths

    CERN Document Server

    Bower, Geoffrey C; Markoff, Sera; Gurwell, Mark A; Rao, Ramprasad; McHardy, Ian

    2015-01-01

    We analyze the light curves of 413 radio sources at submillimeter wavelengths using data from the Submillimeter Array calibrator database. The database includes more than 20,000 observations at 1.3 and 0.8 mm that span 13 years. We model the light curves as a damped random walk and determine a characteristic time scale $\\tau$ at which the variability amplitude saturates. For the vast majority of sources, primarily blazars and BL Lac objects, we find only lower limits on $\\tau$. For two nearby low luminosity active galactic nuclei, M81 and M87, however, we measure $\\tau=1.6^{+3.0}_{-0.9}$ days and $\\tau=45^{+61}_{-24}$ days, respectively ($2\\sigma$ errors). Including the previously measured $\\tau=0.33\\pm 0.16$ days for Sgr A*, we show an approximately linear correlation between $\\tau$ and black hole mass for these nearby LLAGN. Other LLAGN with spectra that peak in the submm are expected to follow this correlation. These characteristic time scales are comparable to the minimum time scale for emission processes...

  1. Tree Tensor Network State with Variable Tensor Order: An Efficient Multireference Method for Strongly Correlated Systems.

    Science.gov (United States)

    Murg, V; Verstraete, F; Schneider, R; Nagy, P R; Legeza, Ö

    2015-03-10

    We study the tree-tensor-network-state (TTNS) method with variable tensor orders for quantum chemistry. TTNS is a variational method to efficiently approximate complete active space (CAS) configuration interaction (CI) wave functions in a tensor product form. TTNS can be considered as a higher order generalization of the matrix product state (MPS) method. The MPS wave function is formulated as products of matrices in a multiparticle basis spanning a truncated Hilbert space of the original CAS-CI problem. These matrices belong to active orbitals organized in a one-dimensional array, while tensors in TTNS are defined upon a tree-like arrangement of the same orbitals. The tree-structure is advantageous since the distance between two arbitrary orbitals in the tree scales only logarithmically with the number of orbitals N, whereas the scaling is linear in the MPS array. It is found to be beneficial from the computational costs point of view to keep strongly correlated orbitals in close vicinity in both arrangements; therefore, the TTNS ansatz is better suited for multireference problems with numerous highly correlated orbitals. To exploit the advantages of TTNS a novel algorithm is designed to optimize the tree tensor network topology based on quantum information theory and entanglement. The superior performance of the TTNS method is illustrated on the ionic-neutral avoided crossing of LiF. It is also shown that the avoided crossing of LiF can be localized using only ground state properties, namely one-orbital entanglement.

  2. Hemodynamic variables and clinical features correlated with serum uric acid in patients with pulmonary arterial hypertension

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Background Serum uric acid (UA), the final product of purine degradation, has been proposed to be a marker for the severity and a possible predictor of mortality in patients with pulmonary arterial hypertension (PAH). The objectives of this study were to elucidate whether serum UA level correlates with the clinical features and the hemodynamic variables in Chinese patients with PAH and to compare the difference of the correlates in patients associated with different etiologies. Methods Serum UA was assessed in 228 patients with three types of PAH (idiopathic PAH (IPAH), congenital heart disease related PAH (CHD-PAH) and connective tissue disease related PAH (CTD-PAH)) together with other clinical features. After the individualized treatment for at least 6 months, the UA levels and clinical features were re-evaluated in 88 patients. Results Serum UA was significantly elevated in patients with PAH compared with age-matched control subjects ((350.40±108.73) μmol/L vs (266.91±81.38) μmol/L), P<0.001). Serum UA negatively correlated with cardiac output and mixed venous saturation (SvO) in all three types of PAH (all P<0.05), positively correlated with the size of right ventricle in IPAH (P=0.002) and CTD-PAH (P=0.013) patients and with pulmonary vascular resistance just in CTD-PAH patients (P=0.001). Serum UA significantly decreased from (365.80±120.46) μmol/L to (333.67±117.56) μmol/L in 88 patients (P=0.006) with vasodilator therapy for at least 6 months, accompanied with a reduction in pulmonary vascular resistance from (15.13±6.96) Woods unit to (12.00±5.04) Woods unit (P=0.001) and an increase in cardiac output from (2.63±0.98) L/min to (3.08±1.04) L/min (P=0.005). Conclusions Serum UA increases in proportion to the clinical severity of all the three types of PAH, especially the CTD-PAH had a stronger correlations compared with IPAH and CHD-PAH. The serum UA levels also could partly reflect the response to the treatment in patients with PAH.

  3. Correlated response in litter size components in rabbits selected for litter size variability.

    Science.gov (United States)

    Argente, M J; Calle, E W; García, M L; Blasco, A

    2017-07-11

    A divergent selection experiment for the environmental variability of litter size (Ve) over seven generations was carried out in rabbits at the University Miguel Hernández of Elche. The Ve was estimated as the phenotypic variance within the female, after correcting for year-season and parity-lactation status. The aim of this study was to analyse the correlated responses to selection in litter size components. The ovulation rate (OR) and number of implanted embryos (IE) in females were measured by laparoscopy at 12 day of the second gestation. At the end of the second gestation, the total number of kits born was measured (TB). Embryonic (ES), foetal (FS) and prenatal (PS) survival were computed as IE/OR, TB/IE and TB/OR, respectively. A total of 405 laparoscopies were performed. Data were analysed using Bayesian methodology. The correlated response to selection for litter size environmental variability in terms of the litter size components was estimated as either genetic trends, estimated by computing the average estimated breeding values for each generation and each line, or the phenotypic differences between lines. The OR was similar in both lines. However, after seven generations of selection, the homogenous line showed more IE (1.09 embryos for genetic means and 1.23 embryos for phenotypic means) and higher ES than the heterogeneous one (0.07 for genetic means and 0.08 for phenotypic means). The probability of the phenotypic differences between lines being higher than zero (p) was 1.00 and .99, respectively. A higher uterine overcrowding of embryos in the homogeneous line did not penalize FS; as a result, this line continued to show a greater TB (1.01 kits for genetic means and 1.30 kits for phenotypic means, p = .99, in the seventh generation). In conclusion, a decrease in litter size variability showed a favourable effect on ES and led to a higher litter size at birth. © 2017 Blackwell Verlag GmbH.

  4. Method of frequency dependent correlations: investigating the variability of total solar irradiance

    Science.gov (United States)

    Pelt, J.; Käpylä, M. J.; Olspert, N.

    2017-03-01

    Context. This paper contributes to the field of modeling and hindcasting of the total solar irradiance (TSI) based on different proxy data that extend further back in time than the TSI that is measured from satellites. Aims: We introduce a simple method to analyze persistent frequency-dependent correlations (FDCs) between the time series and use these correlations to hindcast missing historical TSI values. We try to avoid arbitrary choices of the free parameters of the model by computing them using an optimization procedure. The method can be regarded as a general tool for pairs of data sets, where correlating and anticorrelating components can be separated into non-overlapping regions in frequency domain. Methods: Our method is based on low-pass and band-pass filtering with a Gaussian transfer function combined with de-trending and computation of envelope curves. Results: We find a major controversy between the historical proxies and satellite-measured targets: a large variance is detected between the low-frequency parts of targets, while the low-frequency proxy behavior of different measurement series is consistent with high precision. We also show that even though the rotational signal is not strongly manifested in the targets and proxies, it becomes clearly visible in FDC spectrum. A significant part of the variability can be explained by a very simple model consisting of two components: the original proxy describing blanketing by sunspots, and the low-pass-filtered curve describing the overall activity level. The models with the full library of the different building blocks can be applied to hindcasting with a high level of confidence, Rc ≈ 0.90. The usefulness of these models is limited by the major target controversy. Conclusions: The application of the new method to solar data allows us to obtain important insights into the different TSI modeling procedures and their capabilities for hindcasting based on the directly observed time intervals.

  5. A new approach to the correlation of boundary layer mass transfer rates with thermal diffusion and/or variable properties

    Science.gov (United States)

    Srivastava, R.; Rosner, D. E.

    1979-01-01

    A rational approach to the correlation of boundary layer mass transport rates, applicable to many commonly encountered laminar flow conditions with thermal diffusion and/or variable properties, is outlined. The correlation scheme builds upon already available constant property blowing/suction solutions by introducing appropriate correction factors to account for the additional ('pseudo' blowing and source) effects identified with variable properties and thermal diffusion. Applications of the scheme to the particular laminar boundary layer mass transfer problems considered herein (alkali and transition metal compound vapor transport) indicates satisfactory accuracy up to effective blowing factors equivalent to about one third of the 'blow off' value. As a useful by-product of the variable property correlation, we extend the heat-mass transfer analogy, for a wide range of Lewis numbers, to include variable property effects.

  6. Individual Variability in Sensorimotor Network Functional Connectivity Correlates With the Rate of Early Visuomotor Adaptation

    Science.gov (United States)

    Cassady, K.; Ruitenberg, M.; Koppelmans, V.; DeDios, Y.; Gadd, N.; Wood, S.; Reuter-Lorenz, P.; Riascos, R.; Kofman, I.; Bloomberg, J.; Mulavara, A.; Seidler, R.

    2016-01-01

    Sensorimotor adaptation is a type of procedural motor learning that enables individuals to preserve accurate movements in the presence of external or internal perturbations. Adaptation learning can be divided into an early, more cognitively demanding stage, and a later, more automatic stage. In recent years, several investigations have identified significant associations between sensorimotor adaptation and brain structure and function. However, the question of whether individual variability in functional connectivity strength is predictive of sensorimotor adaptation performance has been largely unaddressed. In the present study, we investigate whether such variability in early sensorimotor adaptation is associated with individual differences in resting-state functional connectivity. We used resting state functional magnetic resonance imaging (rs-fMRI) to estimate functional connectivity strength using hypothesis-driven (seed-to-voxel) and hypothesis-free (voxel-to-voxel) approaches. For the hypothesis-driven analysis, we selected several regions of interest (ROIs) from sensorimotor and default mode networks of the brain. We then correlated these connectivity measures with the rate of early learning during a visuomotor adaptation task in 16 healthy participants. For this task, participants lay supine in the MRI scanner and moved an MRI-compatible dual axis joystick with their right hand to hit targets presented on a screen. Each movement was initiated from the central position on the display screen. Participants were instructed to move the cursor to the target as quickly as possible by moving the joystick, and to hold the cursor within the target until it disappeared. They were then instructed to release the joystick handle after target disappearance, allowing the cursor to re-center for the next trial. Performance was assessed by measuring direction error (DE), defined as the angle between the line from the start to the target position, and the line from the start

  7. Correlating multidimensional fetal heart rate variability analysis with acid-base balance at birth.

    Science.gov (United States)

    Frasch, Martin G; Xu, Yawen; Stampalija, Tamara; Durosier, Lucien D; Herry, Christophe; Wang, Xiaogang; Casati, Daniela; Seely, Andrew Je; Alfirevic, Zarko; Gao, Xin; Ferrazzi, Enrico

    2014-12-01

    Fetal monitoring during labour currently fails to accurately detect acidemia. We developed a method to assess the multidimensional properties of fetal heart rate variability (fHRV) from trans-abdominal fetal electrocardiogram (fECG) during labour. We aimed to assess this novel bioinformatics approach for correlation between fHRV and neonatal pH or base excess (BE) at birth.We enrolled a prospective pilot cohort of uncomplicated singleton pregnancies at 38-42 weeks' gestation in Milan, Italy, and Liverpool, UK. Fetal monitoring was performed by standard cardiotocography. Simultaneously, with fECG (high sampling frequency) was recorded. To ensure clinician blinding, fECG information was not displayed. Data from the last 60 min preceding onset of second-stage labour were analyzed using clinically validated continuous individualized multiorgan variability analysis (CIMVA) software in 5 min overlapping windows. CIMVA allows simultaneous calculation of 101 fHRV measures across five fHRV signal analysis domains. We validated our mathematical prediction model internally with 80:20 cross-validation split, comparing results to cord pH and BE at birth.The cohort consisted of 60 women with neonatal pH values at birth ranging from 7.44 to 6.99 and BE from -0.3 to -18.7 mmol L(-1). Our model predicted pH from 30 fHRV measures (R(2) = 0.90, P birth. Further refinement and validation in larger cohorts are needed. These new measurements of fHRV might offer a new opportunity to predict fetal acid-base balance at birth.

  8. Fractal correlation property of heart rate variability in chronic obstructive pulmonary disease

    Science.gov (United States)

    Carvalho, Tatiana D; Pastre, Carlos Marcelo; de Godoy, Moacir Fernandes; Fereira, Celso; Pitta, Fábio O; de Abreu, Luiz Carlos; Ramos, Ercy Mara Cipulo; Valenti, Vitor E; Vanderlei, Luiz Carlos Marques

    2011-01-01

    Background It was reported that autonomic nervous system function is altered in subjects with chronic obstructive pulmonary disease (COPD). We evaluated short- and long-term fractal exponents of heart rate variability (HRV) in COPD subjects. Patients and methods We analyzed data from 30 volunteers, who were divided into two groups according to spirometric values: COPD (n = 15) and control (n = 15). For analysis of HRV indices, HRV was recorded beat by beat with the volunteers in the supine position for 30 minutes. We analyzed the linear indices in the time (SDNN [standard deviation of normal to normal] and RMSSD [root-mean square of differences]) and frequency domains (low frequency [LF], high frequency [HF], and LF/HF), and the short- and long-term fractal exponents were obtained by detrended fluctuation analysis. We considered P < 0.05 to be a significant difference. Results COPD patients presented reduced levels of all linear exponents and decreased short-term fractal exponent (alpha-1: 0.899 ± 0.18 versus 1.025 ± 0.09, P = 0.026). There was no significant difference between COPD and control groups in alpha-2 and alpha-1/alpha-2 ratio. Conclusion COPD subjects present reduced short-term fractal correlation properties of HRV, which indicates that this index can be used for risk stratification, assessment of systemic disease manifestations, and therapeutic procedures to monitor those patients. PMID:21311690

  9. Inverse Correlation between Heart Rate Variability and Heart Rate Demonstrated by Linear and Nonlinear Analysis.

    Directory of Open Access Journals (Sweden)

    Syed Zaki Hassan Kazmi

    Full Text Available The dynamical fluctuations in the rhythms of biological systems provide valuable information about the underlying functioning of these systems. During the past few decades analysis of cardiac function based on the heart rate variability (HRV; variation in R wave to R wave intervals has attracted great attention, resulting in more than 17000-publications (PubMed list. However, it is still controversial about the underling mechanisms of HRV. In this study, we performed both linear (time domain and frequency domain and nonlinear analysis of HRV data acquired from humans and animals to identify the relationship between HRV and heart rate (HR. The HRV data consists of the following groups: (a human normal sinus rhythm (n = 72; (b human congestive heart failure (n = 44; (c rabbit sinoatrial node cells (SANC; n = 67; (d conscious rat (n = 11. In both human and animal data at variant pathological conditions, both linear and nonlinear analysis techniques showed an inverse correlation between HRV and HR, supporting the concept that HRV is dependent on HR, and therefore, HRV cannot be used in an ordinary manner to analyse autonomic nerve activity of a heart.

  10. Correlated X-ray and optical variability in intermediate polars during their outbursts

    CERN Document Server

    Neustroev, V V; Suleimanov, V; Sjoberg, G

    2016-01-01

    We present a study of the evolution of the optical and X-ray fluxes during outbursts of two short-period cataclysmic variables, the confirmed intermediate polar CC Scl and the intermediate polar candidate FS Aur. We found that the X-ray and optical light curves are well correlated in both objects, although the amplitudes of outbursts in X-rays are smaller than those in the optical. The ratio of the outburst amplitudes in X-rays and the optical in both objects is close to ~0.6. This is significantly higher than was observed during the outburst of the non-magnetic dwarf nova U Gem, in which this ratio was only ~0.03. The obtained data also suggest that the dependence between the X-ray and optical fluxes must steepen significantly toward very low accretion rates and very low fluxes. Similarities in the behaviour of CC Scl and FS Aur indicate strongly the magnetic nature of the white dwarf in FS Aur.

  11. Temperament in bullheads: do laboratory and field explorative behaviour variables correlate?

    Science.gov (United States)

    Kobler, Alexander; Engelen, Brecht; Knaepkens, Guy; Eens, Marcel

    2009-10-01

    The relevance of temperament traits for life history strategy or productivity is increasingly acknowledged. Temperament traits are often either observed in captivity or in the wild, but studies combining both observations are very rare. We examine whether exploratory behaviour in the bullhead (Cottus perifretum), assayed under laboratory conditions, predicts this behaviour under field conditions. Forty-three PIT-tagged individuals were first assayed for exploration of a novel environment in the aquarium and then released into an unfamiliar stream stretch, where they were later relocated using a mobile antenna. Explorative behaviour assayed in the laboratory was significantly positively related to the exploration in the field, thus predicting distance moved in the field release. Both in the laboratory and in the field, explorative behaviour was not related to individual body length. When bullheads that did not leave the refuge in the aquarium (laboratory assay) and, therefore, did not explore the new environment were excluded from the analysis, the correlation between laboratory and field explorative behaviour variables became weaker. However, overall, our results illustrate that exploration rate of bullheads in isolated single-individual experiments can be used to predict this behaviour in the natural ecosystem.

  12. Determining Correlations Between Climatic Variables and Malaria Outbreaks in South Africa, Africa

    Science.gov (United States)

    Yeh, R.; Forsythe, T. S.; Janjic, A.; Ness, S.; Souther, B.; Gunter, G.; Shepherd, M.; Swanson, A. J.

    2008-12-01

    Malaria is a life-threatening disease and is epidemic in the country of South Africa. This study identified the existing correlations between malaria cases and climatic variables to include soil moisture, vegetation, rainfall, and temperature in the provinces Limpopo, Mpumalanga, and Kwazulu-Natal of South Africa. Earth Observation Systems from NASA and partners, including NOAA, were utilized in data collection. The data were imported into Minitab 15, JMP, and Statistical Package for the Social Sciences (SPSS) for statistical analysis. A stepwise regression analysis test for each province led to the formulation of predictability model equations utilizing the best predictors of disease outbreak for each province. All climatic parameters were proven to be statistically significant in Mpumalanga and intermittent results occurred for the other provinces. When evaluating the factors to determine the one most accurate in disease prediction, varying results were found to produce the most accurate model. To better understand malaria outbreaks in epidemic regions, studies must be conducted in other regions. Additionally, comparative analysis of the results are required to determine the accuracy of the predictive models. By establishing a multivariate statistical model, populations will be more knowledgeable of potential outbreaks and preventative measures may be taken to preserve the social and economic health of an area.

  13. Wavelet Correlation Coefficient of 'strongly correlated' financial time series

    OpenAIRE

    Ashok Razdan

    2003-01-01

    In this paper we use wavelet concepts to show that correlation coefficient between two financial data's is not constant but varies with scale from high correlation value to strongly anti-correlation value This studies is important because correlation coefficient is used to quantify degree of independence between two variables. In econophysics correlation coefficient forms important input to evolve hierarchial tree and minimum spanning tree of financial data.

  14. Long-range correlations in heart rate variability during computer-mouse work under time pressure

    Science.gov (United States)

    Jiang, Dineng; He, Mulu; Qiu, Yihong; Zhu, Yisheng; Tong, Shanbao

    2009-04-01

    The aim of this study was to investigate the influences of time pressure on long-range correlations in heart rate variability (HRV), the effects of relaxation on the cardiovascular regulation system and the advantages of detrended fluctuation analysis (DFA) over the conventional power spectral analysis in discriminating states of the cardiovascular systems under different levels of time pressure. Volunteer subjects ( n=10, male/female=5/5) participated in a computer-mouse task consisting of five sessions, i.e. baseline session (BSS) which was free of time pressure, followed by sessions with 80% (SS80), 100% (SS100), 90% (SS90) and 150% (SS150) of the baseline time. Electrocardiogram (ECG) and task performance were recorded throughout the experiments. Two rest sessions before and after the computer-mouse work, i.e. RS1 and RS2, were also recorded as comparison. HRV series were subsequently analyzed by both conventional power spectral analysis and detrended fluctuation analysis (DFA). The long-term scaling exponent α2 by DFA was significantly lower in SS80 than that in other sessions. It was also found that short-term release of time pressure had positive influences on the cardiovascular system, i.e. the α2 in RS2 was significantly higher than that in SS80, SS100 and SS90. No significant differences were found between any two sessions by conventional power spectral analysis. Our results showed that DFA performed better in discriminating the states of cardiovascular autonomic modulation under time pressure than the conventional power spectral analysis.

  15. Correlates to the variable effects of cannabis in young adults: a preliminary study

    Directory of Open Access Journals (Sweden)

    Camera Ariella A

    2012-03-01

    Full Text Available Abstract Background Cannabis use can frequently have adverse affects in those that use it and these can be amplified by various characteristics of an individual, from demographic and environmental variations to familial predisposition for mental illnesses. Methods The current study of 100 individuals, who were cannabis users during their adolescence and may still be users, was a survey of the self perceived effects of cannabis and their correlates. A reliable family member was also interviewed for determination of family history of various major mental illnesses and substance use. Results As many as 40% of cannabis users had paranoid feelings (suspiciousness when using cannabis, although the most frequent effect was feeling relaxed (46%. Having a familial background for mental illnesses such as depression or schizophrenia did not determine the effects of cannabis nor its pattern of use, although the number of subjects with such a history was small. An age at which an individual began using cannabis did have an effect on how heavily it was used and the heavier the cannabis use, the more likely the individual was also to have had psychotic symptoms after use. There were no sex differences in effects of cannabis. These results are tempered by the reliance on self-report for many of the variables ascertained. Conclusion Cannabis can frequently have negative effects in its users, which can be amplified by certain demographic and/or psychosocial factors. Thus, users with a specific profile may be at a higher risk of unpleasant effects from cannabis use and caution should be noted when cannabis is administered to young people for medicinal purposes.

  16. İMKB Betaları, Korelasyon Tahmini ve Değişkenlik = IMKB Betas, Correlation and Variability

    Directory of Open Access Journals (Sweden)

    Mehmet Fuat BEYAZIT

    2005-01-01

    Full Text Available Betas of 46 IMKB companies are computed and adjusted according to Blume and Vasicek techniques. Then using the historical and adjusted betas, correlation coefficients of the stocks are calculated. The method which gives the minimum average absolute error between the correlation coefficients is searched. It is shown that in spite of the periodical changes the overall mean correlation coefficient outperforms the other methods in terms of average absolute error. In order to test the variability of beta coefficients with 12 months data length, a transition matrix is used and shown that the risk class of the stocks change frequently between the period examined.

  17. Genotypic Variability of the Components and their Effects on the Rice Yield: Correlation and Path Analysis Study

    Directory of Open Access Journals (Sweden)

    Sharkhawat Hossain

    2008-06-01

    Full Text Available Twenty modern Boro rice varieties were evaluated with a view to find variability and genetic association for grain yield and yield components characters. Genotypic and Phenotypic correlation among these characters were computed. Both genotypic and phenotypic correlation coefficients were significant between plant height and number of effective tillers per plant followed by panicle length. There was a positive significant correlation between yield and number of effective tillers per plant followed by percent filled grain per panicle. Path coefficient showed that number of effective tiller per plant and plant height are the characters that contribute largely to grain yield.

  18. Calibration of ultra high speed laser engraving processes by correlating influencing variables including correlative evaluation with SEM and CLSM

    Science.gov (United States)

    Bohrer, Markus; Vaupel, Matthias; Nirnberger, Robert; Weinberger, Bernhard

    2016-03-01

    Laser engraving is used for decades as a well-established process e. g. for the production of print and embossing forms for many goods in daily life, e. g. decorated cans and printed bank notes. Up to now it is more or less a so-called fire-and-forget process. From the original artist's plan to the digitization, then from the laser source itself (with electronic signals, RF and plasma discharge regarding CO2 lasers) to the behavior of the optical beam delivery — especially if an AOM is used — to the interaction of the laser beam with the material itself is a long process chain. The most recent results using CO2 lasers with AOMs and the research done with scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM) — as a set for correlative microscopy to evaluate the high speed engraving characteristics — are presented in this paper.

  19. Variability in Pretest-Posttest Correlation Coefficients by Student Achievement Level. NCEE 2011-4033

    Science.gov (United States)

    Cole, Russell; Haimson, Joshua; Perez-Johnson, Irma; May, Henry

    2011-01-01

    State assessments are increasingly used as outcome measures for education evaluations. The scaling of state assessments produces variability in measurement error, with the conditional standard error of measurement increasing as average student ability moves toward the tails of the achievement distribution. This report examines the variability in…

  20. On the Correlations among Affective Variables,Learning Strategies and Language Proficiency

    Institute of Scientific and Technical Information of China (English)

    刘容; 黄俐

    2009-01-01

    Affeetive variables and learning strategies are two important factors that influence language proficiency. In the investigation conducted by the author,there is no sure causal connection being found among the three factors. Further, affective variables seems prevail over learning strategies of the influence on language proficiency and it is the primary element in language study process.

  1. Post-exercise heart-rate recovery correlates to resting heart-rate variability in healthy men.

    Science.gov (United States)

    Molina, Guilherme Eckhardt; Fontana, Keila Elizabeth; Porto, Luiz Guilherme Grossi; Junqueira, Luiz Fernando

    2016-12-01

    The relationship between post-exercise heart-rate recovery (HRR) and resting cardiac autonomic modulation is an incompletely explored issue. To correlate HRR with resting supine and orthostatic autonomic status. HRR at the 1st, 3th, and 5th min following maximal treadmill exercise were correlated with 5-min time-domain (CV, pNN50 and rMSSD) and frequency-domain (TP, LF, HF, LFn, HFn, and LF/HF ratio) indices of heart-rate variability (HRV) in both supine and standing positions in 31 healthy physically active non-athletes men. Statistical analysis employed non-parametric tests with two-tailed p value set at 5 %. Absolute HRR and Δ %HRR at each post-exercise time did not correlated with HRV in supine position, as well as at 1st min in standing position. At the 3rd min and 5th min, these measures negatively correlated with pNN50, rMSSD, TP, and HF indices, and only in the 5th min, they showed negative correlation with HFn and positive correlation with LF, LFn, and LF/HF ratio in the standing position. Coefficient of HRR (CHRR) at the 1st min negatively correlated with pNN50 and rMSSD and at 3rd and 5th min showed positive correlation with LFn and LF/HF ratio in supine position. With HRV indices in standing position CHRR from the 1st to 5th min showed the same respective negative and positive correlations as the other measures. HRR from the 1st to 5th min post-exercise negatively correlated with parasympathetic modulation in resting orthostatic, but showed no correlation in supine position. At the 3rd and 5th min, a positive correlation with combined sympathetic-parasympathetic modulation in both positions was observed.

  2. Recent NDVI-Based Variation in Growth of Boreal Intact Forest Landscapes and Its Correlation with Climatic Variables

    Directory of Open Access Journals (Sweden)

    Jiaxin Jin

    2016-04-01

    Full Text Available Intact Forest Landscape (IFL is of great value in protecting biodiversity and supporting core ecological processes. It is important to analyze the spatial variation in the growth dynamics of IFL. This study analyzed the change of the Normalized Difference Vegetation Index (NDVI during the growing season (April–October for boreal (45° N–70° N IFLs and the correlation with climatic variables over the period of 2000–2013. Our results show 85.5% of boreal IFLs did not show a significant change in the NDVI after 2000, and only 10.2% and 4.3% exhibited a statistically significant increase (greening or decrease (browning in NDVI, respectively. About 60.9% of the greening boreal IFLs showed that an increasing NDVI was significantly correlated to climatic variables, especially an increasing growing season temperature (over 47.0%. For browning boreal IFLs, a decrease in temperature or an increase in dormancy period precipitation could be the prime reason for a significant decrease in the NDVI. However, about 64.6% of the browning boreal IFLs were insensitive to any of the climatic variables, indicating other factors, such as fire, had caused the browning. Although it did not show a significant trend, the NDVI of 51.3% of no-change boreal IFLs significantly correlated to climatic variables, especially growing season temperatures (over 37.6%.

  3. Hybrid correspondence analysis and correlation to analyze the market position from data with two qualitative and p-2 quantitative variables

    Science.gov (United States)

    Ginanjar, Irlandia

    2015-12-01

    Analysis of the market position will be easier, efficient, and informative when based on a perceptual map, that can display objects and characteristics. With perceptual map we can identify the information about the objects similarity, the characteristics relationships, and relationship between the object and the characteristics. Characteristics of the object are usually more than two variables, those variables that sometimes are qualitative and some are quantitative. Based on that this paper introduce a method of analysis called hybrid correspondence analysis and correlation (HCAC), this method is the incorporation of correspondence analysis (CA) with biplot of correlation, where the mapped of two qualitative variables is using CA, and for quantitative variables is using correlations. HCAC produces a perceptual map that displays the object, the qualitative characteristics, and quantitative characteristics in a single map, without changing the quantitative data into qualitative data, so that the information obtained is more complete. A reference for mapping quality is counted from the first and second cumulative percent of eigenvalues where resulting from CA.

  4. Rapid and correlated variability of blazar S5 0716+71 from radio- to sub-mm bands

    CERN Document Server

    Fuhrmann, L; Witzel, A; Agudo, I; Britzen, S; Bernhart, S; Impellizzeri, V; Kraus, A L; Angelakis, E; Bach, U; Gabanyi, K E; Zensus, J A

    2006-01-01

    The BL Lac object S5 0716+71 was target of a coordinated and global multi-frequency campaign to search for rapid and correlated variability and signatures of the inverse-Compton catastrophe. Here we present first results obtained from a combined analysis of the cm- to sub-mm observations over a period of seven days aiming at a detailed study of the intra- to inter-day variability characteristics and to obtain constraints on the variability brightness temperatures and Doppler factors comparing the radio data with the high energy emission recorded by INTEGRAL. A more detailed description of the whole cm- to sub-mm observations and our analysis/results will be presented in a forthcoming paper. Our analysis reveals the source to be in a particular short-term variability phase when compared to the past with a correlated >~4 day time scale amplitude increase of up to 35%, which is systematically more pronounced towards higher frequencies. The obtained frequency dependent variability amplitudes and time lags contrad...

  5. CANONICAL CORRELATION ANALYSIS BETWEEN TIME SERIES AND STATIC OUTCOMES, WITH APPLICATION TO THE SPECTRAL ANALYSIS OF HEART RATE VARIABILITY.

    Science.gov (United States)

    Krafty, Robert T; Hall, Martica

    2013-03-01

    Although many studies collect biomedical time series signals from multiple subjects, there is a dearth of models and methods for assessing the association between frequency domain properties of time series and other study outcomes. This article introduces the random Cramér representation as a joint model for collections of time series and static outcomes where power spectra are random functions that are correlated with the outcomes. A canonical correlation analysis between cepstral coefficients and static outcomes is developed to provide a flexible yet interpretable measure of association. Estimates of the canonical correlations and weight functions are obtained from a canonical correlation analysis between the static outcomes and maximum Whittle likelihood estimates of truncated cepstral coefficients. The proposed methodology is used to analyze the association between the spectrum of heart rate variability and measures of sleep duration and fragmentation in a study of older adults who serve as the primary caregiver for their ill spouse.

  6. Quantification of marine aerosol subgrid variability and its correlation with clouds based on high-resolution regional modeling: Quantifying Aerosol Subgrid Variability

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Guangxing; Qian, Yun; Yan, Huiping; Zhao, Chun; Ghan, Steven J.; Easter, Richard C.; Zhang, Kai

    2017-06-16

    One limitation of most global climate models (GCMs) is that with the horizontal resolutions they typically employ, they cannot resolve the subgrid variability (SGV) of clouds and aerosols, adding extra uncertainties to the aerosol radiative forcing estimation. To inform the development of an aerosol subgrid variability parameterization, here we analyze the aerosol SGV over the southern Pacific Ocean simulated by the high-resolution Weather Research and Forecasting model coupled to Chemistry. We find that within a typical GCM grid, the aerosol mass subgrid standard deviation is 15% of the grid-box mean mass near the surface on a 1 month mean basis. The fraction can increase to 50% in the free troposphere. The relationships between the sea-salt mass concentration, meteorological variables, and sea-salt emission rate are investigated in both the clear and cloudy portion. Under clear-sky conditions, marine aerosol subgrid standard deviation is highly correlated with the standard deviations of vertical velocity, cloud water mixing ratio, and sea-salt emission rates near the surface. It is also strongly connected to the grid box mean aerosol in the free troposphere (between 2 km and 4 km). In the cloudy area, interstitial sea-salt aerosol mass concentrations are smaller, but higher correlation is found between the subgrid standard deviations of aerosol mass and vertical velocity. Additionally, we find that decreasing the model grid resolution can reduce the marine aerosol SGV but strengthen the correlations between the aerosol SGV and the total water mixing ratio (sum of water vapor, cloud liquid, and cloud ice mixing ratios).

  7. Wind Power Curve Modeling Using Statistical Models: An Investigation of Atmospheric Input Variables at a Flat and Complex Terrain Wind Farm

    Energy Technology Data Exchange (ETDEWEB)

    Wharton, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bulaevskaya, V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Irons, Z. [Enel Green Power North America, Andover, MA (United States); Qualley, G. [Infigen Energy, Dallas, TX (United States); Newman, J. F. [Univ. of Oklahoma, Norman, OK (United States); Miller, W. O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-28

    The goal of our FY15 project was to explore the use of statistical models and high-resolution atmospheric input data to develop more accurate prediction models for turbine power generation. We modeled power for two operational wind farms in two regions of the country. The first site is a 235 MW wind farm in Northern Oklahoma with 140 GE 1.68 turbines. Our second site is a 38 MW wind farm in the Altamont Pass Region of Northern California with 38 Mitsubishi 1 MW turbines. The farms are very different in topography, climatology, and turbine technology; however, both occupy high wind resource areas in the U.S. and are representative of typical wind farms found in their respective areas.

  8. Spatio-temporal environmental correlation and population variability in simple metacommunities.

    Directory of Open Access Journals (Sweden)

    Lasse Ruokolainen

    Full Text Available Natural populations experience environmental conditions that vary across space and over time. This variation is often correlated between localities depending on the geographical separation between them, and different species can respond to local environmental fluctuations similarly or differently, depending on their adaptation. How this emerging structure in environmental correlation (between-patches and between-species affects spatial community dynamics is an open question. This paper aims at a general understanding of the interactions between the environmental correlation structure and population dynamics in spatial networks of local communities (metacommunities, by studying simple two-patch, two-species systems. Three different pairs of interspecific interactions are considered: competition, consumer-resource interaction, and host-parasitoid interaction. While the results paint a relatively complex picture of the effect of environmental correlation, the interaction between environmental forcing, dispersal, and local interactions can be understood via two mechanisms. While increasing between-patch environmental correlation couples immigration and local densities (destabilising effect, the coupling between local populations under increased between-species environmental correlation can either amplify or dampen population fluctuations, depending on the patterns in density dependence. This work provides a unifying framework for modelling stochastic metacommunities, and forms a foundation for a better understanding of population responses to environmental fluctuations in natural systems.

  9. Sleep pattern in patients with Chronic Obstructive Pulmonary Disease and correlation among gasometric, spirometric, and polysomnographic variables

    Directory of Open Access Journals (Sweden)

    Santos Carlos Eduardo Ventura Gaio dos

    2003-01-01

    Full Text Available OBJECTIVE: There are few studies on chronic obstructive pulmonary disease (COPD establishing differences between the functional parameters of the disease and sleep variables. The aim of the study was to describe the sleep pattern of these patients and to correlate spirometric, gasometric and polysomnographic variables. METHODS: Transversal study using COPD patients submitted to spirometry, arterial gasometry, and polysomnography. RESULTS: 21 male patients were studied with average age = 67 ± 9; 7 ± 4 average points in the Epworth sleepiness scale, average Tiffenau's index (FEV1/FVC = 54 ± 13.0%, average PaO2 = 68 ± 11 mmHg, average PaCO2 = 37 ± 6 mmHg. Sleep efficiency decreased (65 ± 16% with the reduction of slow wave sleep (8 ± 9% and rapid eye movement (REM sleep (15 ± 8%. Average T90 was 43 ± 41%. Average apnea-hypopnea index (AHI = 3 ± 5/h, where two patients (9.5% presented obstructive sleep apnea. A significant correlation was observed between PaO2 and T90 (p < 0.01, PaCO2 and T90 (p < 0.05, and AHI and the cardiac rate during REM (p < 0.01. A higher number of arousals and stage change was observed. There was no linear correlation between spirometric and polysomnographic variables. CONCLUSION: Poor sleep quality of these patients was characterized by low sleep efficiency, high number of awakenings and shift of stages. There were no correlations between the spirometric and polysomnographic variables.

  10. Optimal Design of a Push-Pull-Forward Half-Bridge (PPFHB) Bidirectional DC–DC Converter With Variable Input Voltage

    DEFF Research Database (Denmark)

    Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

    2012-01-01

    This paper presents a low-cost bidirectional isolated dc–dc converte, derived from dual-active-bridge converter for the power sources with variable output voltage like supercapacitors. The proposed converter consists of push-pull-forward circuit half-bridge circuit (PPFHB) and a high-frequency tr...... by digital signal processor for comparison purpose. Detailed test results verify the theoretical analysis and demonstrate the validity of optimization design method....

  11. Simulated sudden increase in geomagnetic activity and its effect on heart rate variability: Experimental verification of correlation studies

    Science.gov (United States)

    Caswell, Joseph M.; Singh, Manraj; Persinger, Michael A.

    2016-08-01

    Previous research investigating the potential influence of geomagnetic factors on human cardiovascular state has tended to converge upon similar inferences although the results remain relatively controversial. Furthermore, previous findings have remained essentially correlational without accompanying experimental verification. An exception to this was noted for human brain activity in a previous study employing experimental simulation of sudden geomagnetic impulses in order to assess correlational results that had demonstrated a relationship between geomagnetic perturbations and neuroelectrical parameters. The present study employed the same equipment in a similar procedure in order to validate previous findings of a geomagnetic-cardiovascular dynamic with electrocardiography and heart rate variability measures. Results indicated that potential magnetic field effects on frequency components of heart rate variability tended to overlap with previous correlational studies where low frequency power and the ratio between low and high frequency components of heart rate variability appeared affected. In the present study, a significant increase in these particular parameters was noted during geomagnetic simulation compared to baseline recordings.

  12. Methodological considerations regarding response bias effect in substance use research: is correlation between the measured variables sufficient?

    Directory of Open Access Journals (Sweden)

    Petróczi Andrea

    2011-01-01

    Full Text Available Abstract Efforts for drug free sport include developing a better understanding of the behavioural determinants that underline doping with an increased interest in developing anti-doping prevention and intervention programmes. Empirical testing of both is dominated by self-report questionnaires, which is the most widely used method in psychological assessments and sociology polls. Disturbingly, the potential distorting effect of socially desirable responding (SD is seldom considered in doping research, or dismissed based on weak correlation between some SD measure and the variables of interest. The aim of this report is to draw attention to i the potential distorting effect of SD and ii the limitation of using correlation analysis between a SD measure and the individual measures. Models of doping opinion as a potentially contentious issue was tested using structural equation modeling technique (SEM with and without the SD variable, on a dataset of 278 athletes, assessing the SD effect both at the i indicator and ii construct levels, as well as iii testing SD as an independent variable affecting expressed doping opinion. Participants were categorised by their SD score into high- and low SD groups. Based on low correlation coefficients (

  13. Salivary aldehyde dehydrogenase - temporal and population variability, correlations with drinking and smoking habits and activity towards aldehydes contained in food.

    Science.gov (United States)

    Giebułtowicz, Joanna; Dziadek, Marta; Wroczyński, Piotr; Woźnicka, Katarzyna; Wojno, Barbara; Pietrzak, Monika; Wierzchowski, Jacek

    2010-01-01

    Fluorimetric method based on oxidation of the fluorogenic 6-methoxy-2-naphthaldehyde was applied to evaluate temporal and population variability of the specific activity of salivary aldehyde dehydrogenase (ALDH) and the degree of its inactivation in healthy human population. Analyzed was also its dependence on drinking and smoking habits, coffee consumption, and its sensitivity to N-acetylcysteine. Both the specific activity of salivary ALDH and the degree of its inactivation were highly variable during the day, with the highest activities recorded in the morning hours. The activities were also highly variable both intra- and interpersonally, and negatively correlated with age, and this correlation was stronger for the subgroup of volunteers declaring abstinence from alcohol and tobacco. Moderately positive correlations of salivary ALDH specific activity with alcohol consumption and tobacco smoking were also recorded (r(s) ~0.27; p=0.004 and r(s) =0.30; p=0.001, respectively). Moderate coffee consumption correlated positively with the inactivation of salivary ALDH, particularly in the subgroup of non-drinking and non-smoking volunteers. It was found that mechanical stimulation of the saliva flow increases the specific activity of salivary ALDH. The specific activity of the salivary ALDH was strongly and positively correlated with that of superoxide dismutase, and somewhat less with salivary peroxidase. The antioxidant-containing drug N-acetylcysteine increased activity of salivary ALDH presumably by preventing its inactivation in the oral cavity. Some food-related aldehydes, mainly cinnamic aldehyde and anisaldehyde, were excellent substrates of the salivary ALDH3A1 enzyme, while alkenals, particularly those with short chain, were characterized by lower affinity towards this enzyme but high catalytic constants. The protective role of salivary ALDH against aldehydes in food and those found in the cigarette smoke is discussed, as well as its participation in

  14. Students' Daily Emotions in the Classroom: Intra-Individual Variability and Appraisal Correlates

    Science.gov (United States)

    Ahmed, Wondimu; van der Werf, Greetje; Minnaert, Alexander; Kuyper, Hans

    2010-01-01

    Background: Recent literature on emotions in education has shown that competence- and value-related beliefs are important sources of students' emotions; nevertheless, the role of these antecedents in students' daily functioning in the classroom is not yet well-known. More importantly, to date we know little about intra-individual variability in…

  15. SS 433 Radio\\/X-ray anti-correlation and fast-time variability

    CERN Document Server

    Safi-Harb, S; Safi-Harb, Samar; Kotani, Taro

    2002-01-01

    We briefly review the Galactic microquasar SS 433/W50 and present a new RXTE spectral and timing study. We show that the X-ray flux decreases during radio flares, a behavior seen in other microquasars. We also find short time-scale variability unveiling emission regions from within the binary system.

  16. Fouling resistance prediction using artificial neural network nonlinear auto-regressive with exogenous input model based on operating conditions and fluid properties correlations

    Science.gov (United States)

    Biyanto, Totok R.

    2016-06-01

    Fouling in a heat exchanger in Crude Preheat Train (CPT) refinery is an unsolved problem that reduces the plant efficiency, increases fuel consumption and CO2 emission. The fouling resistance behavior is very complex. It is difficult to develop a model using first principle equation to predict the fouling resistance due to different operating conditions and different crude blends. In this paper, Artificial Neural Networks (ANN) MultiLayer Perceptron (MLP) with input structure using Nonlinear Auto-Regressive with eXogenous (NARX) is utilized to build the fouling resistance model in shell and tube heat exchanger (STHX). The input data of the model are flow rates and temperatures of the streams of the heat exchanger, physical properties of product and crude blend data. This model serves as a predicting tool to optimize operating conditions and preventive maintenance of STHX. The results show that the model can capture the complexity of fouling characteristics in heat exchanger due to thermodynamic conditions and variations in crude oil properties (blends). It was found that the Root Mean Square Error (RMSE) are suitable to capture the nonlinearity and complexity of the STHX fouling resistance during phases of training and validation.

  17. Fouling resistance prediction using artificial neural network nonlinear auto-regressive with exogenous input model based on operating conditions and fluid properties correlations

    Energy Technology Data Exchange (ETDEWEB)

    Biyanto, Totok R. [Department of Engineering Physics, Institute Technology of Sepuluh Nopember Surabaya, Surabaya, Indonesia 60111 (Indonesia)

    2016-06-03

    Fouling in a heat exchanger in Crude Preheat Train (CPT) refinery is an unsolved problem that reduces the plant efficiency, increases fuel consumption and CO{sub 2} emission. The fouling resistance behavior is very complex. It is difficult to develop a model using first principle equation to predict the fouling resistance due to different operating conditions and different crude blends. In this paper, Artificial Neural Networks (ANN) MultiLayer Perceptron (MLP) with input structure using Nonlinear Auto-Regressive with eXogenous (NARX) is utilized to build the fouling resistance model in shell and tube heat exchanger (STHX). The input data of the model are flow rates and temperatures of the streams of the heat exchanger, physical properties of product and crude blend data. This model serves as a predicting tool to optimize operating conditions and preventive maintenance of STHX. The results show that the model can capture the complexity of fouling characteristics in heat exchanger due to thermodynamic conditions and variations in crude oil properties (blends). It was found that the Root Mean Square Error (RMSE) are suitable to capture the nonlinearity and complexity of the STHX fouling resistance during phases of training and validation.

  18. Correlations of Back Strength with Selected Anthropometric Variables and Performance Tests in Indian Inter-University Male Field Hockey Players

    Directory of Open Access Journals (Sweden)

    S. Koley

    2017-01-01

    Full Text Available : The purpose of this study was of two-fold: first, to estimate the back strength of Indian inter-university male field hockey players and, second, to search the correlations of it with selected anthropometric variables and performance tests. To serve this purpose, a total of nine anthropometric variables, such as height, weight, body mass index, percent body fat, knee height, length of femur, femur biepicondylar diameter, skeletal mass and back strength, and two performance tests, such as sit and reach test and Slalom sprint and dribble test were measured on purposely selected 120 Indian inter-university male hockey players aged 18–25 years collected from the inter-university competition held in Guru Nanak Dev University, Amritsar, India during March, 2014. An adequate number of controls (n=119 were also taken from the same place for comparison. The results showed that the hockey players had the higher mean values in all the variables, except percent body fat and slalom sprint and dribble test than their control counterparts, showing statistically significant differences (p ≤ 0.003 – 0.001 between them. No significant correlations of back strength were found with any of the variables in Indian inter-university male field hockey players. In conclusion, it may be stated that back strength may not be used as one of the indicating factors for the performance of the field hockey players.

  19. Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009

    CERN Document Server

    Ahnen, M L; Antonelli, L A; Antoranz, P; Babic, A; Banerjee, B; Bangale, P; de Almeida, U Barres; Barrio, J A; González, J Becerra; Bednarek, W; Bernardini, E; Biasuzzi, B; Biland, A; Blanch, O; Bonnefoy, S; Bonnoli, G; Borracci, F; Bretz, T; Buson, S; Carosi, A; Chatterjee, A; Clavero, R; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Covino, S; Da Vela, P; Dazzi, F; De Angelis, A; De Lotto, B; Wilhelmi, E de Oña; Di Pierro, F; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Einecke, S; Glawion, D Eisenacher; Elsaesser, D; Fernández-Barral, A; Fidalgo, D; Fonseca, M V; Font, L; Frantzen, K; Fruck, C; Galindo, D; López, R J García; Garczarczyk, M; Terrats, D Garrido; Gaug, M; Giammaria, P; Godinović, N; Muñoz, A González; Gora, D; Guberman, D; Hadasch, D; Hahn, A; Hanabata, Y; Hayashida, M; Herrera, J; Hose, J; Hrupec, D; Hughes, G; Idec, W; Kodani, K; Konno, Y; Kubo, H; Kushida, J; La Barbera, A; Lelas, D; Lindfors, E; Lombardi, S; Longo, F; López, M; López-Coto, R; Majumdar, P; Makariev, M; Mallot, K; Maneva, G; Manganaro, M; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Menzel, U; Miranda, J M; Mirzoyan, R; Moralejo, A; Moretti, E; Nakajima, D; Neustroev, V; Niedzwiecki, A; Rosillo, M Nievas; Nilsson, K; Nishijima, K; Noda, K; Nogués, L; Orito, R; Overkemping, A; Paiano, S; Palacio, J; Palatiello, M; Paneque, D; Paoletti, R; Paredes, J M; Paredes-Fortuny, X; Pedaletti, G; Perri, L; Persic, M; Poutanen, J; Moroni, P G Prada; Prandini, E; Puljak, I; Rhode, W; Ribó, M; Rico, J; Garcia, J Rodriguez; Saito, T; Satalecka, K; Schultz, C; Schweizer, T; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Stamerra, A; Steinbring, T; Strzys, M; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Thaele, J; Torres, D F; Toyama, T; Treves, A; Verguilov, V; Vovk, I; Ward, J E; Will, M; Wu, M H; Zanin, R; Blinov, D A; Chen, W P; Efimova, N V; Forné, E; Grishina, T S; Hovatta, T; Jordan, B; Kimeridze, G N; Kopatskaya, E N; Koptelova, E; Kurtanidze, O M; Kurtanidze, S O; Lähteenmaäki, A; Larionov, V M; Larionova, E G; Larionova, L V; Ligustri, R; Lin, H C; McBreen, B; Morozova, D A; Nikolashvili, M G; Raiteri, C M; Ros, J A; Sadun, A C; Sigua, L A; Tornikoski, M; Troitsky, I S; Villata, M

    2016-01-01

    We study the multi-band variability and correlations of the TeV blazar Mrk 421 on year time scales, which can bring additional insight on the processes responsible for its broadband emission. We observed Mrk 421 in the very high energy (VHE) gamma-ray range with the Cherenkov telescope MAGIC-I from March 2007 to June 2009 for a total of 96 hours of effective time after quality cuts. The VHE flux variability is quantified with several methods, including the Bayesian Block algorithm, which is applied to data from Cherenkov telescopes for the first time. The 2.3 year long MAGIC light curve is complemented with data from the Swift/BAT and RXTE/ASM satellites and the KVA, GASP-WEBT, OVRO, and Mets\\"ahovi telescopes from February 2007 to July 2009, allowing for an excellent characterisation of the multi-band variability and correlations over year time scales. Mrk 421 was found in different gamma-ray emission states during the 2.3 year long observation period. Flares and different levels of variability in the gamma-...

  20. Effect of data gaps on correlation dimension computed from light curves of variable stars

    CERN Document Server

    George, Sandip V; Misra, R

    2015-01-01

    Observational data, especially astrophysical data, is often limited by gaps in data that arises due to lack of observations for a variety of reasons. Such inadvertent gaps are usually smoothed over using interpolation techniques. However the smoothing techniques can introduce artificial effects, especially when non-linear analysis is undertaken. We investigate how gaps can affect the computed values of correlation dimension of the system, without using any interpolation. For this we introduce gaps artificially in synthetic data derived from standard chaotic systems, like the R{\\"o}ssler and Lorenz, with frequency of occurrence and size of missing data drawn from two Gaussian distributions. Then we study the changes in correlation dimension with change in the distributions of position and size of gaps. We find that for a considerable range of mean gap frequency and size, the value of correlation dimension is not significantly affected, indicating that in such specific cases, the calculated values can still be ...

  1. Seasonal variations of DNA damage in human lymphocytes: Correlation with different environmental variables

    Energy Technology Data Exchange (ETDEWEB)

    Giovannelli, Lisa [Dipartimento di Farmacologia Preclinica e Clinica, Universita di Firenze, Viale Pieraccini 6, 50139 Florence (Italy)]. E-mail: lisa.giovannelli@unifi.it; Pitozzi, Vanessa [Dipartimento di Farmacologia Preclinica e Clinica, Universita di Firenze, Viale Pieraccini 6, 50139 Florence (Italy); Moretti, Silvia [Department of Dermatological Sciences, University of Florence, Florence (Italy); Boddi, Vieri [Department of Public Health, University of Florence, Florence (Italy); Dolara, Piero [Dipartimento di Farmacologia Preclinica e Clinica, Universita di Firenze, Viale Pieraccini 6, 50139 Florence (Italy)

    2006-01-29

    Several types of DNA damage, including DNA breaks and DNA base oxidation, display a seasonal trend. In the present work, a sample of 79 healthy subjects living in the city of Florence, Italy, was used to analyse this effect. Three possible causative agents were taken into consideration: solar radiation, air temperature and air ozone level. DNA damage was measured in isolated human lymphocytes at different times during the year and the observed damage was correlated with the levels of these three agents in the days preceding blood sampling. Three time windows were chosen: 3, 7 and 30 days before blood sampling. DNA strand breaks and the oxidized purinic bases cleaved by the formamidopyrimidine glycosylase (FPG sites) were measured by means of the comet assay. The results of multivariate regression analysis showed a positive correlation between lymphocyte DNA damage and air temperature, and a less strong correlation with global solar radiation and air ozone levels.

  2. Correlation between sea surface temperature and wind speed in Greenland Sea and their relationships with NAO variability

    Directory of Open Access Journals (Sweden)

    Bo QU

    2012-09-01

    Full Text Available The North Atlantic Oscillation (NAO is one of the major causes of many recent changes in the Arctic Ocean. Generally, it is related to wind speed, sea surface temperature (SST, and sea ice cover. In this study, we analyzed the distributions of and correlations between SST, wind speed, NAO, and sea ice cover from 2003 to 2009 in the Greenland Sea at 10°W to 10°E, 65°N to 80°N. SST reached its peak in July, while wind speed reached its minimum in July. Seasonal variability of SST and wind speed was different for different regions. SST and wind speed mainly had negative correlations. Detailed correlation research was focused on the 75°N to 80°N band. Regression analysis shows that in this band, the variation of SST lagged three months behind that of wind speed. Ice cover and NAO had a positive correlation, and the correlation coefficient between ice cover and NAO in the year 2007 was 0.61. SST and NAO also had a positive correlation, and SST influenced NAO one month in advance. The correlation coefficients between SST and NAO reached 0.944 for the year 2005, 0.7 for the year 2008, and 0.74 for the year 2009 after shifting SST one month later. NAO also had a positive correlation with wind speed, and it also influenced wind speed one month in advance. The correlation coefficients between NAO and wind speed reached 0.783, 0.813, and 0.818 for the years 2004, 2005, and 2008, respectively, after shifting wind speed one month earlier.

  3. A Parallel Approach in Computing Correlation Immunity up to Six Variables

    Science.gov (United States)

    2015-07-24

    andersm2@union.edu Eric Bach Computer Sciences Department, University of Wisconsin, Madison, WI 53706, U.S.A.; bach @cs.wisc.edu Jon T. Butler ECE...INSTRUCTION FILE CorImm 2 C. Etherington, M. A. Anderson, E. Bach , J. T. Butler, P. Stănică 1. Introduction The correlation immunity of a Boolean function...Etherington, M. A. Anderson, E. Bach , J. T. Butler, P. Stănică (resiliency) k but not k + 1, we will describe such a function as exact correlation

  4. Product mix variability with correlated demand in two-stage food manufacturing with intermediate storage

    NARCIS (Netherlands)

    Akkerman, Renzo; van Donk, Dirk Pieter

    2009-01-01

    In food processing, market demands are increasingly important, resulting in regular introductions of new products, or special offers. Often, such all introduction or promotional effort affects demand of other products or packaging types. Here we study the effect of such correlated demand. More

  5. Inputs from regularly and irregularly discharging vestibular nerve afferents to secondary neurons in squirrel monkey vestibular nuclei. III. Correlation with vestibulospinal and vestibuloocular output pathways

    Science.gov (United States)

    Boyle, R.; Goldberg, J. M.; Highstein, S. M.

    1992-01-01

    1. A previous study measured the relative contributions made by regularly and irregularly discharging afferents to the monosynaptic vestibular nerve (Vi) input of individual secondary neurons located in and around the superior vestibular nucleus of barbiturate-anesthetized squirrel monkeys. Here, the analysis is extended to more caudal regions of the vestibular nuclei, which are a major source of both vestibuloocular and vestibulospinal pathways. As in the previous study, antidromic stimulation techniques are used to classify secondary neurons as oculomotor or spinal projecting. In addition, spinal-projecting neurons are distinguished by their descending pathways, their termination levels in the spinal cord, and their collateral projections to the IIIrd nucleus. 2. Monosynaptic excitatory postsynaptic potentials (EPSPs) were recorded intracellularly from secondary neurons as shocks of increasing strength were applied to Vi. Shocks were normalized in terms of the threshold (T) required to evoke field potentials in the vestibular nuclei. As shown previously, the relative contribution of irregular afferents to the total monosynaptic Vi input of each secondary neuron can be expressed as a %I index, the ratio (x100) of the relative sizes of the EPSPs evoked by shocks of 4 x T and 16 x T. 3. Antidromic stimulation was used to type secondary neurons as 1) medial vestibulospinal tract (MVST) cells projecting to spinal segments C1 or C6; 2) lateral vestibulospinal tract (LVST) cells projecting to C1, C6; or L1; 3) vestibulooculo-collic (VOC) cells projecting both to the IIIrd nucleus and by way of the MVST to C1 or C6; and 4) vestibuloocular (VOR) neurons projecting to the IIIrd nucleus but not to the spinal cord. Most of the neurons were located in the lateral vestibular nucleus (LV), including its dorsal (dLV) and ventral (vLV) divisions, and adjacent parts of the medial (MV) and descending nuclei (DV). Cells receiving quite different proportions of their direct inputs

  6. Long range correlations in the heart rate variability following the injury of cardiac arrest

    Science.gov (United States)

    Tong, Shanbao; Jiang, Dineng; Wang, Ziming; Zhu, Yisheng; Geocadin, Romeryko G.; Thakor, Nitish V.

    2007-07-01

    Cardiovascular and neurological recovery following cardiac arrest (CA) largely influence the morbidity and mortality of the patients. Monitoring the cardiovascular system has been an important clinical issue in intensive care unit (ICU). On the other hand, the rhythms of the heart rate variability following CA are still not fully understood, and there are limited number of literatures reporting the cardiovascular function recovery following CA. In this paper, we studied the scaling properties of heart rate variability (HRV) after CA by centered-moving-average-based detrended fluctuation analysis (DFA). Our results showed that the scaling factor of the baseline HRV is close to that of Brownian motion, and after a CA event it shifts to a 1/f noise-like rhythm. DFA could be a promising tool in evaluating the cardiovascular long term recovery following CA injury.

  7. Variability and correlations in muskmelon in relation to the cultivation method.

    Science.gov (United States)

    Molina, R V; Nuez, F; Cuartero, J; Goméz-Guillamón, M L; Abadía, J

    1989-09-01

    Six fruit characters have been measured in 23 cultivars of Cucumis melo, representing a wide geographical range. Plants were grown both in the greenhouse and in the field. When the 23 cultivars were analyzed together, the largest component of variance was found between cultivars under both growth conditions, suggesting the existence of large genetic diversity for all the characters studied. Generally, variance between plants within cultivars was less than or equal to variance between fruits within plant. This indicates that environmental variation is the most important part of the variation within cultivars. Correlations between pairs of characters at cultivar, plant and fruit levels were calculated from the variance-covariance components. In the majority of paired traits, the correlation values indicated that genetic and environmental factors may act in the same direction.

  8. Variability and correlation between basic quality parameters of raw cow milk

    OpenAIRE

    Memiši N.; Bogdanović V.; Tomić Z.; Kasalica A.; Žujović M.; Stanišić N.; Delić N.

    2011-01-01

    In this paper the results of the analysis of the milk somatic cell count are presented, as well as correlation between the somatic cell count and content of certain chemical parameters in milk (milk proteins, fat, lactose and dry matter without fat) determined in collective samples of milk obtained from cows reared in intensive rearing system, during two production years. The research was carried out by control of collective milk samples from cows reared on...

  9. Hf isotope evidence for variable slab input and crustal addition in basalts and andesites of the Taupo Volcanic Zone, New Zealand

    DEFF Research Database (Denmark)

    Waight, Tod Earle; Troll, Valentin R.; Gamble, J.A.

    2017-01-01

    variations likely represent variability in primary magma compositions as a result of different degrees of sediment addition at the slab-wedge interface. Coupled variations in isotopic composition, LILE/HFSE ratios (e.g. Rb/Zr and Ba/La) and SiO2 also clearly indicate that shallower level crustal interactions......Crustal contamination complicates the identification of primary mantle-derived magma compositions in Continental arcs. However,when crustal processes and components arewell characterised, it is possible to extrapolate through continental arc magma compositional arrays towards the Hf and Nd isotope...... compositions of uncontaminated primary magmas. This is because of the similar behaviour of Hf and Nd during fractional crystallisation and mantle melting, and the subsequent limited variation in Hf/Nd in mantle-derived magmas and in many crustal lithologies, resulting in linear contamination trends for Hf...

  10. Brain Morphometric Correlates of Metabolic Variables in HIV: The CHARTER Study

    Science.gov (United States)

    ARCHIBALD, S.L.; MCCUTCHAN, J.A.; SANDERS, C.; WOLFSON, T.; JERNIGAN, T.L.; ELLIS, R.J.; ANCES, B.M.; COLLIER, A.C.; MCARTHUR, J.C.; MORGELLO, S.; SIMPSON, D.M.; MARRA, C.; GELMAN, B.B.; CLIFFORD, D.B.; GRANT, I.; FENNEMA-NOTESTINE, C.

    2014-01-01

    Objectives: Obesity and other metabolic variables are associated with abnormal brain structural volumes and cognitive dysfunction in HIV-uninfected populations. Since individuals with HIV infection on combined antiretroviral therapy (CART) often have systemic metabolic abnormalities and changes in brain morphology and function, we examined associations among brain volumes and metabolic factors in the multi-site CNS HIV Anti-Retroviral Therapy Effects Research (CHARTER) cohort. Design: Cross-sectional study of 222 HIV-infected individuals. Methods: Metabolic variables included body mass index (BMI), total blood cholesterol (C), low- and high-density lipoprotein C (LDL-C and HDL-C), blood pressure, random blood glucose, and diabetes. MRI measured volumes of cerebral white matter, abnormal white matter, cortical and subcortical gray matter, and ventricular and sulcal CSF. Multiple linear regression models allowed us to examine metabolic variables separately and in combination to predict each regional volume. Results: Greater body mass index (BMI) was associated with smaller cortical gray and larger white matter volumes. Higher total cholesterol (C) levels were associated with smaller cortex volumes; higher LDL-C was associated with larger cerebral white matter volumes, while higher HDL-C levels were associated with larger sulci. Higher blood glucose levels and diabetes were associated with more abnormal white matter. Conclusions: Multiple atherogenic metabolic factors contribute to regional brain volumes in HIV-infected, CART-treated patients, reflecting associations similar to those found in HIV-uninfected individuals. These risk factors may accelerate cerebral atherosclerosis and consequent brain alterations and cognitive dysfunction. PMID:25227933

  11. ANTI-CORRELATED OPTICAL FLUX AND POLARIZATION VARIABILITY IN BL LAC

    Energy Technology Data Exchange (ETDEWEB)

    Gaur, Haritma [Inter-University Centre for Astronomy and Astrophysics (IUCAA), Ganeshkhind, Pune 411 007 (India); Gupta, Alok C. [Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital 263 129 (India); Wiita, Paul J. [Department of Physics, The College of New Jersey, P.O. Box 7718, Ewing, NJ 08628-0718 (United States); Uemura, Makoto; Itoh, Ryosuke; Sasada, Mahito, E-mail: haritma@iucaa.ernet.in [Hiroshima Astrophysical Science Center, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526 (Japan)

    2014-01-20

    We present the results of photometric (V band) and polarimetric observations of the blazar BL Lac during 2008-2010 using TRISPEC attached to the KANATA 1.5 m telescope in Japan. The data reveal a great deal of variability ranging from days to months with detection of strong variations in fractional polarization. The V band flux strongly anticorrelates with the degree of polarization during the first of two observing seasons but not during the second. The direction of the electric vector, however, remained roughly constant during all of our observations. These results are consistent with a model with at least two emission regions being present, with the more variable component having a polarization direction nearly perpendicular to that of the relatively quiescent region so that a rising flux can produce a decline in degree of polarization. We also computed models involving helical jet structures and single transverse shocks in jets and show that they might also be able to agree with the anticorrelations between flux and fractional polarization.

  12. Mass Measurements of AGN from Multi-Lorentzian Models of X-ray Variability. I. Sampling Effects in Theoretical Models of the rms^2-M_BH Correlation

    DEFF Research Database (Denmark)

    Pessah, Martin Elias

    2006-01-01

    Recent X-ray variability studies suggest that the log of the square of the fractional rms variability amplitude, rms^2, seems to correlate with the log of the AGN black-hole mass, M_BH, with larger black holes being less variable for a fixed time interval. This has motivated the theoretical...

  13. Spatio-Temporal Trends and Identification of Correlated Variables with Water Quality for Drinking-Water Reservoirs

    Directory of Open Access Journals (Sweden)

    Qing Gu

    2015-10-01

    Full Text Available It is widely accepted that characterizing the spatio-temporal trends of water quality parameters and identifying correlated variables with water quality are indispensable for the management and protection of water resources. In this study, cluster analysis was used to classify 56 typical drinking water reservoirs in Zhejiang Province into three groups representing different water quality levels, using data of four water quality parameters for the period 2006–2010. Then, the spatio-temporal trends in water quality were analyzed, assisted by geographic information systems (GIS technology and statistical analysis. The results indicated that the water quality showed a trend of degradation from southwest to northeast, and the overall water quality level was exacerbated during the study period. Correlation analysis was used to evaluate the relationships between water quality parameters and ten independent variables grouped into four categories (land use, socio-economic factors, geographical features, and reservoir attributes. According to the correlation coefficients, land use and socio-economic indicators were identified as the most significant factors related to reservoir water quality. The results offer insights into the spatio-temporal variations of water quality parameters and factors impacting the water quality of drinking water reservoirs in Zhejiang Province, and they could assist managers in making effective strategies to better protect water resources.

  14. Substance use and misuse among 17- to 18-year-old Croatian adolescents: correlation with scholastic variables and sport factors.

    Science.gov (United States)

    Modric, Toni; Zenic, Natasa; Sekulic, Damir

    2011-01-01

    Substance use and misuse (SUM) and the relation to physical activity/exercise/athletic participation (sport factors) and scholastic achievement are rarely studied in Croatia. The aim of this study was: (1) to investigate the SUM habits in Croatian adolescents (17-18 years of age, 254 males, and 218 females), and (2) to study potential gender-specific interrelationships between scholastic and sport factors in relation to SUM. The testing was done using an extensive, anonymous, self-administered questionnaire that consisted of scholastic variables, sport factors, and SUM data. Descriptive statistics, counts, and proportions were calculated. Gender differences were established using the Kruskal-Wallis test. Gender-specific correlations within and between studied variables were established using the Spearman's correlation. The incidence of smoking habits and alcohol consumption among Croatian adolescents was alarming, and a serious intervention program should be developed to address this issue. Educational achievement was negatively related to SUM, with no gender-specific relationships. The data indicated some "protective" effects of the sport factors against SUM in boys, but a significant positive correlation between alcohol drinking and sport participation in girls was also noted.

  15. Spatio-Temporal Trends and Identification of Correlated Variables with Water Quality for Drinking-Water Reservoirs.

    Science.gov (United States)

    Gu, Qing; Wang, Ke; Li, Jiadan; Ma, Ligang; Deng, Jinsong; Zheng, Kefeng; Zhang, Xiaobin; Sheng, Li

    2015-10-20

    It is widely accepted that characterizing the spatio-temporal trends of water quality parameters and identifying correlated variables with water quality are indispensable for the management and protection of water resources. In this study, cluster analysis was used to classify 56 typical drinking water reservoirs in Zhejiang Province into three groups representing different water quality levels, using data of four water quality parameters for the period 2006-2010. Then, the spatio-temporal trends in water quality were analyzed, assisted by geographic information systems (GIS) technology and statistical analysis. The results indicated that the water quality showed a trend of degradation from southwest to northeast, and the overall water quality level was exacerbated during the study period. Correlation analysis was used to evaluate the relationships between water quality parameters and ten independent variables grouped into four categories (land use, socio-economic factors, geographical features, and reservoir attributes). According to the correlation coefficients, land use and socio-economic indicators were identified as the most significant factors related to reservoir water quality. The results offer insights into the spatio-temporal variations of water quality parameters and factors impacting the water quality of drinking water reservoirs in Zhejiang Province, and they could assist managers in making effective strategies to better protect water resources.

  16. Bone Mineral Density in Patients with Ankylosing Spondylitis: Incidence and Correlation with Demographic and Clinical Variables

    Directory of Open Access Journals (Sweden)

    Laura MUNTEAN

    2009-12-01

    Full Text Available Objective: To evaluate bone mineral density (BMD in patients with ankylosing spondylitis (AS and determine its correlation with the demographic and clinical characteristics of AS. Patients and Methods: Demographic, clinical and osteodensitometric data were evaluated in a cross-sectional study that included 136 patients with AS. Spine and hip BMD were measured by means of dual energy X-ray absorptiometry (DXA. Using the modified Schober’s test we assessed spine mobility. We examined the sacroiliac, anteroposterior and lateral dorso-lumbar spine radiographs in order to grade sacroiliitis and assess syndesmophytes. Disease activity was evaluated using C-reactive protein (CRP levels and erythrocyte sedimentation rate (ESR. Demographic data and BMD measurements were compared with those of 167 age- and sex-matched healthy controls. Results: Patients with AS had a significantly lower BMD at the spine, femoral neck, trochanter and total hip as compared to age-matched controls (all p<0.01. According to the WHO classification, osteoporosis was present in 20.6% of the AS patients at the lumbar spine and in 14.6% at the femoral neck. There were no significant differences in BMD when comparing men and women with AS, except for trochanter BMD that was lower in female patients. No correlations were found between disease activity markers (ESR, CRP and BMD. Femoral neck BMD was correlated with disease duration, Schober’s test and sacroiliitis grade. Conclusion: Patients with AS have a lower spine and hip BMD as compared to age- and sex-matched controls. Bone loss at the femoral neck is associated with disease duration and more severe AS.

  17. Variability in the correlation between Asian dust storms and chlorophyll a concentration from the North to Equatorial Pacific.

    Science.gov (United States)

    Tan, Sai-Chun; Yao, Xiaohong; Gao, Hui-Wang; Shi, Guang-Yu; Yue, Xu

    2013-01-01

    A long-term record of Asian dust storms showed seven high-occurrence-frequency centers in China. The intrusion of Asian dust into the downwind seas, including the China seas, the Sea of Japan, the subarctic North Pacific, the North Pacific subtropical gyre, and the western and eastern Equatorial Pacific, has been shown to add nutrients to ocean ecosystems and enhance their biological activities. To explore the relationship between the transported dust from various sources to the six seas and oceanic biological activities with different nutrient conditions, the correlation between monthly chlorophyll a concentration in each sea and monthly dust storm occurrence frequencies reaching the sea during 1997-2007 was examined in this study. No correlations were observed between dust and chlorophyll a concentration in the atmospheric deposition is commonly believed to exert less impact on coastal seas. Significant correlations existed between dust sources and many sea areas, suggesting a link between dust and chlorophyll a concentration in those seas. However, the correlation coefficients were highly variable. In general, the correlation coefficients (0.54-0.63) for the Sea of Japan were highest, except for that between the subarctic Pacific and the Taklimakan Desert, where it was as high as 0.7. For the >50 m China seas and the North Pacific subtropical gyre, the correlation coefficients were in the range 0.32-0.57. The correlation coefficients for the western and eastern Equatorial Pacific were relatively low (dust sources, the transport pathways, the dust deposition, the nutrient conditions of oceans, and the probability of dust storms reaching the seas.

  18. Long-term multi-wavelength variability and correlation study of Markarian 421 from 2007 to 2009

    Science.gov (United States)

    Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; Banerjee, B.; Bangale, P.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Buson, S.; Carosi, A.; Chatterjee, A.; Clavero, R.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; de Oña Wilhelmi, E.; Di Pierro, F.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Eisenacher Glawion, D.; Elsaesser, D.; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; Galindo, D.; García López, R. J.; Garczarczyk, M.; Garrido Terrats, D.; Gaug, M.; Giammaria, P.; Godinović, N.; González Muñoz, A.; Gora, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Hanabata, Y.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Idec, W.; Kodani, K.; Konno, Y.; Kubo, H.; Kushida, J.; La Barbera, A.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; Majumdar, P.; Makariev, M.; Mallot, K.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Miranda, J. M.; Mirzoyan, R.; Moralejo, A.; Moretti, E.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nilsson, K.; Nishijima, K.; Noda, K.; Nogués, L.; Orito, R.; Overkemping, A.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Pedaletti, G.; Perri, L.; Persic, M.; Poutanen, J.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Rhode, W.; Ribó, M.; Rico, J.; Rodriguez Garcia, J.; Saito, T.; Satalecka, K.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Stamerra, A.; Steinbring, T.; Strzys, M.; Takalo, L.; Takami, H.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Torres, D. F.; Toyama, T.; Treves, A.; Verguilov, V.; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zanin, R.

    2016-09-01

    Aims: We study the multi-band variability and correlations of the TeV blazar Mrk 421 on year timescales, which can bring additional insight on the processes responsible for its broadband emission. Methods: We observed Mrk 421 in the very high energy (VHE) γ-ray range with the Cherenkov telescope MAGIC-I from March 2007 to June 2009 for a total of 96 h of effective time after quality cuts. The VHE flux variability is quantified using several methods, including the Bayesian Block algorithm, which is applied to data from Cherenkov telescopes here for the first time. The 2.3 yr long MAGIC light curve is complemented with data from the Swift/BAT and RXTE/ASM satellites and the KVA, GASP-WEBT, OVRO, and Metsähovi telescopes from February 2007 to July 2009, allowing for an excellent characterisation of the multi-band variability and correlations over year timescales. Results: Mrk 421 was found in different γ-ray emission states during the 2.3 yr long observation period: The flux above 400 GeV spans from the minimum nightly value of (1.3 ± 0.4)×10-11 cm-2 s-1 to the maximum flux, that is about 24 times higher, at (3.1 ± 0.1)×10-10 cm-2 s-1. Flares and different levels of variability in the γ-ray light curve could be identified with the Bayesian Block algorithm. The same behaviour of a quiet and active emission was found in the X-ray light curves measured by Swift/BAT and the RXTE/ASM, with a direct correlation in time. The behaviour of the optical light curve of GASP-WEBT and the radio light curves by OVRO and Metsähovi are different as they show no coincident features with the higher energetic light curves and a less variable emission. Overall, the fractional variability increases with energy. The comparable variability in the X-ray and VHE bands and their direct correlation during both high- and low-activity periods spanning many months show that the electron populations radiating the X-ray and γ-ray photons are either the same, as expected in the synchrotron

  19. Pan-STARRS1 variability of XMM-COSMOS AGN. II. Physical correlations and power spectrum analysis

    CERN Document Server

    Simm, T; Saglia, R; Ponti, G; Lanzuisi, G; Nandra, K; Bender, R

    2016-01-01

    [Abbreviated] We search for scaling relations between the fundamental AGN parameters and rest-frame UV/optical variability properties for a sample of $\\sim$90 X-ray selected AGNs covering a wide redshift range from the XMM-COSMOS survey, with optical light curves in four bands provided by the Pan-STARRS1 (PS1) Medium Deep Field 04 survey. To estimate the variability amplitude we utilize the normalized excess variance ($\\sigma_{\\mathrm{rms}}^{2}$) and probe variability on rest-frame timescales of several months and years by calculating $\\sigma_{\\mathrm{rms}}^{2}$ from different parts of our light curves. In addition, we derive the rest-frame optical PSD for our sources using continuous-time autoregressive moving average (CARMA) models. We observe that the excess variance and the PSD amplitude are strongly anti-correlated with wavelength, bolometric luminosity and Eddington ratio. There is no evidence for a dependency of the variability amplitude on black hole mass and redshift. These results suggest that the a...

  20. LINE-1 hypomethylation in cancer is highly variable and inversely correlated with microsatellite instability.

    Directory of Open Access Journals (Sweden)

    Marcos R H Estécio

    Full Text Available BACKGROUND: Alterations in DNA methylation in cancer include global hypomethylation and gene-specific hypermethylation. It is not clear whether these two epigenetic errors are mechanistically linked or occur independently. This study was performed to determine the relationship between DNA hypomethylation, hypermethylation and microsatellite instability in cancer. METHODOLOGY/PRINCIPAL FINDINGS: We examined 61 cancer cell lines and 60 colorectal carcinomas and their adjacent tissues using LINE-1 bisulfite-PCR as a surrogate for global demethylation. Colorectal carcinomas with sporadic microsatellite instability (MSI, most of which are due to a CpG island methylation phenotype (CIMP and associated MLH1 promoter methylation, showed in average no difference in LINE-1 methylation between normal adjacent and cancer tissues. Interestingly, some tumor samples in this group showed increase in LINE-1 methylation. In contrast, MSI-showed a significant decrease in LINE-1 methylation between normal adjacent and cancer tissues (P<0.001. Microarray analysis of repetitive element methylation confirmed this observation and showed a high degree of variability in hypomethylation between samples. Additionally, unsupervised hierarchical clustering identified a group of highly hypomethylated tumors, composed mostly of tumors without microsatellite instability. We extended LINE-1 analysis to cancer cell lines from different tissues and found that 50/61 were hypomethylated compared to peripheral blood lymphocytes and normal colon mucosa. Interestingly, these cancer cell lines also exhibited a large variation in demethylation, which was tissue-specific and thus unlikely to be resultant from a stochastic process. CONCLUSION/SIGNIFICANCE: Global hypomethylation is partially reversed in cancers with microsatellite instability and also shows high variability in cancer, which may reflect alternative progression pathways in cancer.

  1. Estimates of volume and magma input in crustal magmatic systems from zircon geochronology: the effect of modelling assumptions and system variables

    Science.gov (United States)

    Caricchi, Luca; Simpson, Guy; Schaltegger, Urs

    2016-04-01

    Magma fluxes in the Earth's crust play an important role in regulating the relationship between the frequency and magnitude of volcanic eruptions, the chemical evolution of magmatic systems and the distribution of geothermal energy and mineral resources on our planet. Therefore, quantifying magma productivity and the rate of magma transfer within the crust can provide valuable insights to characterise the long-term behaviour of volcanic systems and to unveil the link between the physical and chemical evolution of magmatic systems and their potential to generate resources. We performed thermal modelling to compute the temperature evolution of crustal magmatic intrusions with different final volumes assembled over a variety of timescales (i.e., at different magma fluxes). Using these results, we calculated synthetic populations of zircon ages assuming the number of zircons crystallising in a given time period is directly proportional to the volume of magma at temperature within the zircon crystallisation range. The statistical analysis of the calculated populations of zircon ages shows that the mode, median and standard deviation of the populations varies coherently as function of the rate of magma injection and final volume of the crustal intrusions. Therefore, the statistical properties of the population of zircon ages can add useful constraints to quantify the rate of magma injection and the final volume of magmatic intrusions. Here, we explore the effect of different ranges of zircon saturation temperature, intrusion geometry, and wall rock temperature on the calculated distributions of zircon ages. Additionally, we determine the effect of undersampling on the variability of mode, median and standards deviation of calculated populations of zircon ages to estimate the minimum number of zircon analyses necessary to obtain meaningful estimates of magma flux and final intrusion volume.

  2. Estimates of volume and magma input in crustal magmatic systems from zircon geochronology: the effect of modelling assumptions and system variables

    Directory of Open Access Journals (Sweden)

    Luca eCaricchi

    2016-04-01

    Full Text Available Magma fluxes in the Earth’s crust play an important role in regulating the relationship between the frequency and magnitude of volcanic eruptions, the chemical evolution of magmatic systems and the distribution of geothermal energy and mineral resources on our planet. Therefore, quantifying magma productivity and the rate of magma transfer within the crust can provide valuable insights to characterise the long-term behaviour of volcanic systems and to unveil the link between the physical and chemical evolution of magmatic systems and their potential to generate resources. We performed thermal modelling to compute the temperature evolution of crustal magmatic intrusions with different final volumes assembled over a variety of timescales (i.e., at different magma fluxes. Using these results, we calculated synthetic populations of zircon ages assuming the number of zircons crystallising in a given time period is directly proportional to the volume of magma at temperature within the zircon crystallisation range. The statistical analysis of the calculated populations of zircon ages shows that the mode, median and standard deviation of the populations varies coherently as function of the rate of magma injection and final volume of the crustal intrusions. Therefore, the statistical properties of the population of zircon ages can add useful constraints to quantify the rate of magma injection and the final volume of magmatic intrusions.Here, we explore the effect of different ranges of zircon saturation temperature, intrusion geometry, and wall rock temperature on the calculated distributions of zircon ages. Additionally, we determine the effect of undersampling on the variability of mode, median and standards deviation of calculated populations of zircon ages to estimate the minimum number of zircon analyses necessary to obtain meaningful estimates of magma flux and final intrusion volume.

  3. A correlational study of preadmission predictor variables and dental school performance.

    Science.gov (United States)

    Kress, G C; Dogon, I L

    1981-04-01

    The purpose of this study was to determine the predictive validity of preadmission scores on the performance of 131 students from nine successive classes at the Harvard School of Dental Medicine. The predictors included high school rank, SAT Verbal and Quantitative, selectivity of undergraduate college, college GPA, and DAT Academic, and PAT averages. The performance scores included science GPA, clinical GPA, oral examination scores, and scores on Parts I and II of the dental National Board examinations. Correlation coefficients were calculated between each predictor and performance measure. Only one was significantly greater than zero: DAT Academic average was positively related to Part II Board scores (r = .29). The apparent lack of validity of the other predictors was attributed to their restricted range.

  4. A study of meteorological variables in some extreme environments via cross correlations

    Science.gov (United States)

    Cruz-Kuri, L.; McKay, C. P.; Navarro-Gonzalez, R.

    Some of us have been studying soils in the Atacama Desert, Chile and in Pico de Orizaba, Mexico. The Atacama, is an extreme, arid, temperate desert that extends across 1000 km with monthly mean air temperatures between 16 to 14°C and is remarkably uniform throughout the year (±3°C). Pico de Orizaba (19° N) is a mountain that possesses a glacier and has tropical alpine environments. Both of such environments are of interest as models for Mars. Meteorological data for the Yungay area of the Atacama Desert, as well as meteorological data of the Northern and Southern faces of Pico de Orizaba have been collected. Both sets of data were analyzed using the cross correlation technique of multivariate time series. In this report we describe some of the patterns found for these statistics.

  5. THE CONSTRUCTION OF AN ECONOMIC INDICATOR VARIABLES AND FINANCIAL CORPORATE INVESTMENT GRADE: STATISTICAL TREATMENT OF CORRELATIONS AND REGRESSIONS

    Directory of Open Access Journals (Sweden)

    SERGIO CAVAGNOLI GUTH

    2015-09-01

    Full Text Available In a competitive and globalized economic environment, organizations need to evolve to keep up with changes that the environment imposes on them, seeking sustainability and perpetuity. To the extent that increases the pace of change, the durability of business strategies decreases, causing the need of continuous transformations, with permanent restructuring. The objective of this study is to analyze the correlations and regression models coming from the economic and financial ratios stemmed profitability, profitability, liquidity and debt, based on the corporations that owned the investment grade certification in 2008, issued by certification International, Standard & Poor's, Moody's and Fitch Ratings. The proposed methodology for the setting of this study is typically quantitative, based on statistical analysis of correlation and regression. It was found through this study that the variables studied, could be the basis for the construction of an economic and financial indicator of investment grade. Keywords: Investment Grade. Indicator. Corporations.

  6. Testing in a Random Effects Panel Data Model with Spatially Correlated Error Components and Spatially Lagged Dependent Variables

    Directory of Open Access Journals (Sweden)

    Ming He

    2015-11-01

    Full Text Available We propose a random effects panel data model with both spatially correlated error components and spatially lagged dependent variables. We focus on diagnostic testing procedures and derive Lagrange multiplier (LM test statistics for a variety of hypotheses within this model. We first construct the joint LM test for both the individual random effects and the two spatial effects (spatial error correlation and spatial lag dependence. We then provide LM tests for the individual random effects and for the two spatial effects separately. In addition, in order to guard against local model misspecification, we derive locally adjusted (robust LM tests based on the Bera and Yoon principle (Bera and Yoon, 1993. We conduct a small Monte Carlo simulation to show the good finite sample performances of these LM test statistics and revisit the cigarette demand example in Baltagi and Levin (1992 to illustrate our testing procedures.

  7. Estimation of elastic modulus of reinforcement corrosion products using inverse analysis of digital image correlation measurements for input in corrosion-induced cracking model

    DEFF Research Database (Denmark)

    Pease, Bradley Justin; Michel, Alexander; Thybo, Anna Emilie A.;

    2012-01-01

    A combined experimental and numerical approach for estimating the elastic modulus of reinforcement corrosion products is presented. Deformations between steel and mortar were measured using digital image correlation during accelerated corrosion testing at 100 μA/cm2 (~1.16 mm/year). Measured...... deformations were compared to a numerical corrosion model that considers electrochemical, transport, and mechanical processes, including penetration of corrosion products into a ‘corrosion-accommodating region,’ provided by the mortar’s capillary porosity, directly surrounding the steel. Comparing model...... and experimental results provides an order-of-magnitude approximation of corrosion product stiffness of 2.0 GPa....

  8. Genetic variables of various manifestations of osteochondrosis and their correlations between and within joints in Dutch warmblood horses.

    Science.gov (United States)

    van Grevenhof, E M; Schurink, A; Ducro, B J; van Weeren, P R; van Tartwijk, J M F M; Bijma, P; van Arendonk, J A M

    2009-06-01

    Osteochondrosis (OC) is an important orthopedic developmental disorder in many horse populations. A review of the literature revealed widely variable heritability estimates for the disorder. We estimated the genetic variables (heritabilities and genetic correlations) of various manifestations of OC. Femoropatellar, tarsocrural, and metacarpophalangeal and metatarsophalangeal joints of 811 randomly selected yearlings from the Royal Warmblood Studbook of The Netherlands, descending from 32 representative stallions, were scored for OC at 28 predilection sites. At each site, OC was scored in 5 categories, distinguishing between flattened bone contours and fragments. At the animal level, the overall heritability of OC was 0.23, the heritability of flattened bone contours was 0.08, and the heritability of fragments was 0.22. At the joint level, heritability was greatest in the tarsocrural joints, intermediate in the metacarpophalangeal and metatarsophalangeal joints, and least in the femoropatellar joints. The heritability estimates for the contralateral joint homologs were very similar. The genetic correlation between the tarsocrural and femoropatellar joint was strong, whereas correlations between the metacarpophalangeal and metatarsophalangeal and other joints were moderate. The genetic correlation between flattened bone contours and fragments at the animal level was 0.80. Scoring OC on a 5-point categorical scale resulted in greater heritability on the observed scale than when analyzing OC as a binary trait. Our results suggest that selection against OC could best be performed by taking into account the OC status of all 4 joints, the femoropatellar, the tarsocrural, and the metacarpophalangeal and metatarsophalangeal joints, and discerning between flattened bone contours and fragments.

  9. On the Variability and Correlation of Surface Ozone and Carbon Monoxide Observed in Hong Kong Using Trajectory and Regression Analyses

    Institute of Scientific and Technical Information of China (English)

    WANG Tijian(王体健); K. S. LAM; C. W. TSANG; S. C. KOT

    2004-01-01

    This paper investigates,the variability and correlation of surface ozone (03) and carbon monoxide (CO) observed at Cape D'Aguilar in Hong Kong from I January 1994 to 31 December 1995.Statistical analysis shows that the average 03 and CO mixing ratios during the two years are 32:k17 ppbv and 305:k191ppbv,respectively.The O3/CO ratio ranges from 0.05 to 0.6 ppbv/ppbv with its frequency peaking at 0.15.The raw dataset is divided into six groups using backward trajectory and cluster analyses.For data assigned to the same trajectory type,three groups are further sorted out based on CO and NOx mixing ratios.The correlation coefficients and slopes of O3/CO for the 18 groups are calculated using linear regression analysis.Final]y,five kinds of air masses with different chemical features are identified:continental background (CB),marine background (MB),regional polluted continental (RPC),perturbed marine (P'M),and local polluted (LP) air masses.Further studies indicate that 03 and CO in the continental and marine background air masses (CB and MB) are positively correlated for the reason that they are well mixed over the long range transport before arriving at the site.The negative correlation between 03 and CO in air mass LP is believed to be associated with heavy anthropogenic influence,which results from the enhancement by local sources as indicated by high CO and NOx and depletion of 03 when mixed with fresh emissions.The positive correlation in the perturbed marine air mass P*M favors the low photochemical production of 03.The negative,correlation found in the regional polluted continental air mass RPC is different from the observations at Oki Island in Japan due to the more complex 03 chemistry at Cape D'Aguilar.

  10. Multiwavelength Observations of Markarian 421 in March 2001: an Unprecedented View on the X-ray/TeV Correlated Variability

    CERN Document Server

    Fossati, G; Bond, I H; Bradbury, S M; Carter-Lewis, D A; Chow, Y C K; Cui, W; Falcone, A D; Finley, J P; Gaidos, J A; Grube, J; Holder, J; Horan, D; Kieda, D B; Kildea, J; Krawczynski, H; Krennrich, F; Lang, M J; Le Bohec, S; Lee, K; Moriarty, P; Ong, R A; Petry, D; Quinn, J; Sembroski, G H; Wakely, S P; Weekes, T C

    2007-01-01

    (Abridged) We present a detailed analysis of week-long simultaneous observations of the blazar Mrk421 at 2-60 keV X-rays (RXTE) and TeV gamma-rays (Whipple and HEGRA) in 2001. The unprecedented quality of this dataset enables us to establish firmly the existence of the correlation between the TeV and X-ray luminosities, and to start unveiling some of its more detailed characteristics, in particular its energy dependence, and time variability. The source shows strong, highly correlated variations in X-ray and gamma-ray. No evidence of X-ray/gamma-ray interband lag is found on the full week dataset (<3 ks). However, a detailed analysis of the March 19 flare reveals that data are not consistent with the peak of the outburst in the 2-4 keV X-ray and TeV band being simultaneous. We estimate a 2.1+/-0.7 ks TeV lag. The amplitudes of the X-ray and gamma-ray variations are also highly correlated, and the TeV luminosity increases more than linearly w.r.t. the X-ray one. The strong correlation supports the standard ...

  11. Time-varying correlations between delta EEG power and heart rate variability in midlife women: the SWAN Sleep Study.

    Science.gov (United States)

    Rothenberger, Scott D; Krafty, Robert T; Taylor, Briana J; Cribbet, Matthew R; Thayer, Julian F; Buysse, Daniel J; Kravitz, Howard M; Buysse, Evan D; Hall, Martica H

    2015-04-01

    No studies have evaluated the dynamic, time-varying relationship between delta electroencephalographic (EEG) sleep and high frequency heart rate variability (HF-HRV) in women. Delta EEG and HF-HRV were measured during sleep in 197 midlife women (M(age)  = 52.1, SD = 2.2). Delta EEG-HF-HRV correlations in nonrapid eye movement (NREM) sleep were modeled as whole-night averages and as continuous functions of time. The whole-night delta EEG-HF-HRV correlation was positive. The strongest correlations were observed during the first NREM sleep period preceding and following peak delta power. Time-varying correlations between delta EEG-HF-HRV were stronger in participants with sleep-disordered breathing and self-reported insomnia compared to healthy controls. The dynamic interplay between sleep and autonomic activity can be modeled across the night to examine within- and between-participant differences including individuals with and without sleep disorders.

  12. Correlation between technetium and lithium in a sample of oxygen-rich AGB variables

    CERN Document Server

    Uttenthaler, Stefan

    2009-01-01

    The aims of this paper are: 1) to revisit the Tc content of a sample of oxygen-rich asymptotic giant branch (AGB) variables and 2) to increase the number of such stars for which the Li abundance has been measured to provide constraints on theoretical models of extra-mixing processes. To this end, we analysed high-resolution spectra of 18 sample stars for the presence of absorption lines of Tc and Li. The abundance of the latter was determined by comparing the observed spectra to hydrostatic MARCS model spectra. Bolometric magnitudes were established from near-IR photometry and pulsation periods. We reclassify the star V441 Cyg as Tc-rich, and the unusual Mira star R Hya, as well as W Eri, as Tc-poor. The abundance of Li, or an upper limit to it, was determined for all of the sample stars. In all stars with Tc we also detected Li. Most of them have a Li content slightly below the solar photospheric value, except for V441 Cyg, which has ~1000 times the solar abundance. We also found that, similar to Tc, a lower...

  13. Social relationships and intraindividual variability in interpersonal behavior: correlates of interpersonal spin.

    Science.gov (United States)

    Côté, Stéphane; Moskowitz, D S; Zuroff, David C

    2012-03-01

    Personality constructs are typically conceptualized as central tendencies of the individual. We explore whether dynamic personality constructs that quantify the within-individual variability of behavior across situations and over time predict the closeness of social relationships. We focused on interpersonal spin, defined as the degree of dispersion in a person's interpersonal behaviors around the interpersonal circumplex across situations and over time. We predicted that individuals with high spin would have social relationships that are less close than individuals with low spin. In 3 studies with different measures of relationship closeness, we found that (a) higher spinners reported that a larger proportion of their contacts in their workplace social networks were distant (Study 1); (b) co-workers were less satisfied and less often engaged in pleasant activities with higher spinners (Study 2); and (c) co-workers avoided higher spinners with whom they were well acquainted (Study 3). Moderated mediation analyses in Study 3 revealed that co-workers avoided well-acquainted higher spinners because they felt more negative affect when interacting with these individuals. The findings suggest the potential of dynamic personality constructs for improving our understanding of the characteristics of individuals' social relationships.

  14. Problems of correlations between explanatory variables in multiple regression analyses in the dental literature.

    Science.gov (United States)

    Tu, Y-K; Kellett, M; Clerehugh, V; Gilthorpe, M S

    2005-10-01

    Multivariable analysis is a widely used statistical methodology for investigating associations amongst clinical variables. However, the problems of collinearity and multicollinearity, which can give rise to spurious results, have in the past frequently been disregarded in dental research. This article illustrates and explains the problems which may be encountered, in the hope of increasing awareness and understanding of these issues, thereby improving the quality of the statistical analyses undertaken in dental research. Three examples from different clinical dental specialties are used to demonstrate how to diagnose the problem of collinearity/multicollinearity in multiple regression analyses and to illustrate how collinearity/multicollinearity can seriously distort the model development process. Lack of awareness of these problems can give rise to misleading results and erroneous interpretations. Multivariable analysis is a useful tool for dental research, though only if its users thoroughly understand the assumptions and limitations of these methods. It would benefit evidence-based dentistry enormously if researchers were more aware of both the complexities involved in multiple regression when using these methods and of the need for expert statistical consultation in developing study design and selecting appropriate statistical methodologies.

  15. Eelgrass Leaf Surface Microbiomes Are Locally Variable and Highly Correlated with Epibiotic Eukaryotes

    Directory of Open Access Journals (Sweden)

    Mia M. Bengtsson

    2017-07-01

    Full Text Available Eelgrass (Zostera marina is a marine foundation species essential for coastal ecosystem services around the northern hemisphere. Like all macroscopic organisms, it possesses a microbiome (here defined as an associated prokaryotic community which may play critical roles in modulating the interaction of eelgrass with its environment. For example, its leaf surface microbiome could inhibit or attract eukaryotic epibionts which may overgrow the eelgrass leading to reduced primary productivity and subsequent eelgrass meadow decline. We used amplicon sequencing of the 16S and 18S rRNA genes of prokaryotes and eukaryotes to assess the leaf surface microbiome (prokaryotes as well as eukaryotic epibionts in- and outside lagoons on the German Baltic Sea coast. Prokaryote microbiomes varied substantially both between sites inside lagoons and between open coastal and lagoon sites. Water depth, leaf area and biofilm chlorophyll a concentration explained a large amount of variation in both prokaryotic and eukaryotic community composition. The prokaryotic microbiome and eukaryotic epibiont communities were highly correlated, and network analysis revealed disproportionate co-occurrence between a limited number of eukaryotic taxa and several bacterial taxa. This suggests that eelgrass leaf surfaces are home to a mosaic of microbiomes of several epibiotic eukaryotes, in addition to the microbiome of the eelgrass itself. Our findings thereby underline that eukaryotic diversity should be taken into account in order to explain prokaryotic microbiome assembly and dynamics in aquatic environments.

  16. Interindividual variability in functional connectivity as long-term correlate of temporal discounting.

    Directory of Open Access Journals (Sweden)

    Cinzia Calluso

    Full Text Available During intertemporal choice (IT future outcomes are usually devaluated as a function of the delay, a phenomenon known as temporal discounting (TD. Based on task-evoked activity, previous neuroimaging studies have described several networks associated with TD. However, given its relevance for several disorders, a critical challenge is to define a specific neural marker able to predict TD independently of task execution. To this aim, we used resting-state functional connectivity MRI (fcMRI and measured TD during economic choices several months apart in 25 human subjects. We further explored the relationship between TD, impulsivity and decision uncertainty by collecting standard questionnaires on individual trait/state differences. Our findings indicate that fcMRI within and between critical nodes of task-evoked neural networks associated with TD correlates with discounting behavior measured a long time afterwards, independently of impulsivity. Importantly, the nodes form an intrinsic circuit that might support all the mechanisms underlying TD, from the representation of subjective value to choice selection through modulatory effects of cognitive control and episodic prospection.

  17. Integrating affective and cognitive correlates of heart rate variability: A structural equation modeling approach.

    Science.gov (United States)

    Mann, Sarah L; Selby, Edward A; Bates, Marsha E; Contrada, Richard J

    2015-10-01

    High frequency heart rate variability (HRV) is a measure of neurocardiac communication thought to reflect predominantly parasympathetic cardiac regulation. Low HRV has been associated empirically with clinical and subclinical levels of anxiety and depression and, more recently, high levels of HRV have been associated with better performance on some measures of executive functioning (EF). These findings have offered support for theories proposing HRV as an index measure of a broad, self-regulatory capacity underlying aspects of emotion regulation and executive control. This study sought to test that proposition by using a structural equation modeling approach to examine the relationships of HRV to negative affect (NA) and EF in a large sample of U.S. adults ages 30s-80s. HRV was modeled as a predictor of an NA factor (self-reported trait anxiety and depression symptoms) and an EF factor (performance on three neuropsychological tests tapping facets of executive abilities). Alternative models also were tested to determine the utility of HRV for predicting NA and EF, with and without statistical control of demographic and health-related covariates. In the initial structural model, HRV showed a significant positive relationship to EF and a nonsignificant relationship to NA. In a covariate-adjusted model, HRV's associations with both constructs were nonsignificant. Age emerged as the only significant predictor of NA and EF in the final model, showing inverse relationships to both. Findings may reflect population and methodological differences from prior research; they also suggest refinements to the interpretations of earlier findings and theoretical claims regarding HRV.

  18. Resolving microsatellite genotype ambiguity in populations of allopolyploid and diploidized autopolyploid organisms using negative correlations between allelic variables.

    Science.gov (United States)

    Clark, Lindsay V; Schreier, Andrea Drauch

    2016-11-21

    A major limitation in the analysis of genetic marker data from polyploid organisms is non-Mendelian segregation, particularly when a single marker yields allelic signals from multiple, independently segregating loci (isoloci). However, with markers such as microsatellites that detect more than two alleles, it is sometimes possible to deduce which alleles belong to which isoloci. Here, we describe a novel mathematical property of codominant marker data when it is recoded as binary (presence/absence) allelic variables: under random mating in an infinite population, two allelic variables will be negatively correlated if they belong to the same locus, but uncorrelated if they belong to different loci. We present an algorithm to take advantage of this mathematical property, sorting alleles into isoloci based on correlations, then refining the allele assignments after checking for consistency with individual genotypes. We demonstrate the utility of our method on simulated data, as well as a real microsatellite data set from a natural population of octoploid white sturgeon (Acipenser transmontanus). Our methodology is implemented in the R package polysat version 1.6.

  19. Variable effects of acoustic trauma on behavioral and neural correlates of tinnitus in individual animals

    Directory of Open Access Journals (Sweden)

    Ryan James Longenecker

    2016-10-01

    Full Text Available The etiology of tinnitus is known to be diverse in the human population. An appropriate animal model of tinnitus should incorporate this pathological diversity. Previous studies evaluating the effect of acoustic over exposure (AOE have found that animals typically display increased spontaneous firing rates and bursting activity of auditory neurons, which often has been linked to behavioral evidence of tinnitus. However, only a subset of studies directly associated these neural correlates to individual animals. Furthermore the vast majority of tinnitus studies were conducted on anesthetized animals. The goal of this study was to test for a possible relationship between tinnitus, hearing loss, hyperactivity, and bursting activity in the auditory system of individual unanesthetized animals following AOE. Sixteen mice were unilaterally exposed to 116dB SPL narrowband noise (centered at 12.5 kHz for 1 hour under ketamine/xylazine anesthesia. Gap-induced prepulse inhibition of the acoustic startle reflex (GPIAS was used to assess behavioral evidence of tinnitus whereas hearing performance was evaluated by measurements of auditory brainstem response (ABR thresholds and prepulse inhibition (PPI audiometry. Following behavioral assessments, single neuron firing activity was recorded from the inferior colliculus (IC of four awake animals and compared to recordings from four unexposed controls. We found that AOE increased spontaneous activity in all mice tested, independently of tinnitus behavior or severity of threshold shifts. Bursting activity did not increase in two animals identified as tinnitus positive (T+, but did so in a tinnitus negative (T- animal with severe hearing loss (SHL. Hyperactivity does not appear to be a reliable biomarker of tinnitus. Our data suggest that multidisciplinary assessments on individual animals following AOE could offer a powerful experimental tool to investigate mechanisms of tinnitus.

  20. Constitutive immune defences correlate with life-history variables in tropical birds.

    Science.gov (United States)

    Lee, K A; Wikelski, M; Robinson, W D; Robinson, T R; Klasing, K C

    2008-03-01

    1. It has been suggested that immune defences are shaped by life history and ecology, but few general patterns have been described across species. We hypothesized that 'fast' life-history traits (e.g. short development times, large clutch sizes) would be associated with developmentally inexpensive immune defences, minimizing the resource demands of young animals' immune systems during periods of rapid growth. Conversely, 'slow' life histories should be associated with well developed antibody-mediated defences, which are developmentally costly. 2. We therefore predicted that 'fast-living' species would exhibit higher levels of complement proteins, a component of non-specific innate defence, but lower levels of constitutive ('natural') antibodies. Additionally, we predicted that constitutive immune defences in general would be higher in species with ecological characteristics that might increase exposure to pathogens, such as open nests, omnivorous diets, gregariousness, and closed forested habitat. 3. Across 70 Neotropical bird species, we found a strongly positive relationship between incubation period and natural antibody levels in adult birds, suggesting that longer developmental times might allow the production of a more diverse and/or more reactive adaptive immune system. Complement activity was positively, although weakly, correlated with clutch size, providing some support for the hypothesis that faster-living species rely more on innate defences, such as complement. Unexpectedly, solitary species had higher natural antibody titres than species that frequently join flocks. 4. Our results suggest that, despite probably widespread differences in the intensity and diversity of pathogen exposure, species-level variation in constitutive immune defences is understandable within the context of life-history theory.

  1. VARIABILITY AND CORRELATION OF AGRONOMIC CHARACTERS OF MUNGBEAN GERMPLASM AND THEIR UTILIZATION FOR VARIETY IMPROVEMENT PROGRAM Lukman Hakim

    Directory of Open Access Journals (Sweden)

    Lukman Hakim

    2016-10-01

    Full Text Available Information on the variability and correlation between agronomic characters of mungbean accessions with their yield are important for supporting breeding program of the plant. A total of 350 mungbean accessions were evaluated at Muara Experimental Farm, Indonesian Center for Food Crops Research and Development, Bogor, during the dry season of 2005. The experiment was conducted in a completely randomized block design with three replications. Each accession was planted in two rows of 5 m long. Plant spacing was 40 cm x 20 cm, two plants per hill. Correlation and path coefficient analyses were used to quantifythe magnitude of the relationship between yield components and grain yield. The variability among the accessions was significant for most of the characters studied, especially for days to maturity, plant height, pods per plant, and seed size. Among the yield components, the number of pods per plant and plant height positively correlated with the grain yield, but theseed size negatively correlated with grain yield. The direct effects of the number of pods per plant and plant height on seed yield as indicated by path coefficient were the highest, while other causal effects were small or negative. Yield variation (1- R2 attributable to the nine yield component variables was slightly high (61.23%, which means that mungbean accessions with high grain yield should have sufficient plant height and high number of pods per plant. Therefore, these parameters (number of pods per plant and plant height can be used as the selection criteria in mungbean breeding program. These criteria can be visualized during bulk selection on the early generation stage of F2 to F4, and subsequently on line development of individual plant (pedigree of F5.

  2. A search in the COS-B data base for correlated time variability in regions containing objects of interest

    Science.gov (United States)

    Caraveo, P. A.; Buccheri, R.; Clear, J.; Foa, O.; Pollock, A. M. T.

    1985-01-01

    As is well known, association of the gamma-ray sources with celestial objects is, in general, difficult on a pure positional basis, while correlated time variability could obviously provide such proof. This technique can be employed on regions of the gamma-ray sky containing interesting objects of known variability at some wavelength even in the absence of a recognized gamma-ray excess with the aim to extract a weak but predictable signal from the surrounding noise. This technique is applied here on a longer variability time scale, generally of the order of days. Photons coming from the sky regions centered on the various celestial objects considered were selected with energies 100 MeV and with arrival directions within an energy-dependent area of radius of approx 6 deg at 100 MeV. In order to construct a time profile of such photons, their arrival times were grouped in bins of dimensions defined by the available photons number and by the value of the period searched for.

  3. Synaptic input changes to spinal cord motoneurons correlate with motor control impairments in a type 1 diabetes mellitus model.

    Science.gov (United States)

    Benitez, Suzana Ulian; Carneiro, Everardo Magalhães; de Oliveira, Alexandre Leite Rodrigues

    2015-10-01

    Hyperglycemia is the main cause of diabetic complications, contributing to a widespread degeneration of the nervous system. Nevertheless, the main focus has been the sensory neurons because of neuropathic pain, while the impairments associated with the spinal cord and motor deficits, mostly of those initiated at early stages of the disease, have been poorly investigated. In this way, the present study used the nonobese diabetic mouse model to evaluate the microenvironment around motoneurons at ventral horn of the spinal cord, following prolonged hyperglycemia. Adult female mice were divided into two groups: spontaneously diabetic (n = 33) and nondiabetic (n = 26). Mice were considered hyperglycemic when blood glucose surpassed 400 mg/dL. Following 2 weeks from that stage, part of the animals was euthanized and the lumbar intumescences were obtained and processed for immunohistochemistry and transmission electron microscopy. For immunohistochemistry, the antibodies used for integrated density of pixels quantification were anti-synaptophysin, anti-GFAP, and anti-Iba1. The functional analysis was monitored with the walking track test (CatWalk system) during 4 weeks. The results revealed significant motor impairment in diabetic animals in comparison to the control group. Such loss of motor control correlated with a significant reduction in presynaptic terminals apposed to the motoneurons. Nevertheless, there were no significant changes in glial reaction in the spinal cord. Overall, the results herein revealed central nervous system changes at early stages of the disease that may in turn contribute to the motor deficit. Such changes open a new window of investigation in early stages of diabetes to better comprehend motor impairment as a long-term complication of the disease.

  4. Research on variable input washout algorithm for stewart platform vehicle simulator%六自由度平台车辆运动模拟器变输入洗出算法

    Institute of Scientific and Technical Information of China (English)

    罗竹辉; 魏燕定; 周晓军; 魏春雨

    2013-01-01

    For the purpose of enhancing the fidelity of Stewart platform vehicle simulator simulating dynamic motions of an actual vehicle, a variable input washout algorithm was proposed in combination with classic washout algorithm. Input signal of classic washout algorithm was differentiated and transformed based on the workspace of the simulator. High amplitude input signal was scaled to restrict the workspace of the simulator within its kinematic limitation. Low amplitude input signal was transformed by multiplying a time-varying proportionality coefficient. The time-varying proportionality coefficient was obtained using fuzzy adaptive algorithm. The inputs,output and rules of the fuzzy controller were set by the relationship between the human perception in the simulator and human perception in the vehicle and the input signal of the classic washout algorithm. The signal was taken as an example to simulate the perception about single degree of vehicle longitudinal motions, which was generated by real time dynamic software of the simulator. It shows that with the presented algorithm the simulator can not exceed the bound of the platform, and at the same time it can exploit the workspace of simulator efficiently and improve the fidelity of Stewart platform vehicle simulator simulating dynamic motions of an actual vehicle.%为提高六自由度平台车辆模拟器模拟真实车辆运动感觉的逼真度,结合经典洗出算法提出一种变输入洗出算法.根据模拟器运动空间,对经典洗出算法的输入信号按幅值大小进行划分、变换处理.高幅值输入信号采用缩放处理,以防止超出平台运动空间;低幅值输入信号乘上一个时变比例系数,时变比例系数的确定采用模糊自适应算法,根据人体在运动模拟器上的运动感觉、人体在车辆上的运动感觉以及输入信号的情况,选定模糊控制器的输入、输出和模糊控制规则.以车辆纵向加速度的模拟为例进行仿真,仿真

  5. Spatial Variability of Strontium Distribution Coefficients and Their Correlation With Hydraulic Conductivity in the Canadian Forces Base Borden Aquifer

    Science.gov (United States)

    Robin, M. J. L.; Sudicky, E. A.; Gillham, R. W.; Kachanoski, R. G.

    1991-10-01

    Distribution coefficients (Kd), defined as the ratio of the concentration of solute associated with the solids to the concentration in solution, are widely used in the prediction of reactive solute transport. With the advent of stochastic approaches to describe solute transport, there is a need to examine the spatial distribution of Kd, and its correlation with the hydraulic conductivity (K). Distribution coefficients were measured in triplicates for strontium on 1279 subsamples of cores from Canadian Forces Base Borden for which K measurements were available. The Kd values ranged from 4.4 to 29.8 mL/g, with a mean of 9.9 and standard deviation of 2.89 mL/g. The standard error on the triplicate means was 0.95 mL/g or approximately 10% of the mean. The spatial behavior of Kd and K (expressed as In (Kd) and ln (K)) was examined in three directions: horizontally along two orthogonal transects and vertically. The two variables each behaved nearly identically in the two horizontal directions, suggesting horizontal isotropy. Horizontally, ln (Kd) appeared as "white noise" suggesting that the horizontal spacing between cores (1 m) was too large to detect any self-correlation. The distribution coefficient displayed increasing power spectral density with increasing scale in the vertical direction, while In (K) showed these trends in all directions. Depending on the model used, the, correlation lengths obtained by least squares fits of the power spectra varied from 1 to 7.5 m horizontally and from 10 to 30 cm vertically for ln (K); and from 30 cm to 2 m horizontally and from 30 to 70 cm vertically for ln (Kd). The ln (Kd) values showed a significant but very weak negative overall correlation with ln (K) at the 99.95% confidence level. The cross-spectral and coherency analysis showed that the sign and degree of correlation between ln (Kd) and ln (K) depended on the scale and direction considered. The correlations in all directions and at all scales were weak, and could not

  6. Quantification of topographic changes in the surface of back of young patients monitored for idiopathic scoliosis: correlation with radiographic variables

    Science.gov (United States)

    Pino-Almero, Laura; Mínguez-Rey, María Fe; Sentamans-Segarra, Salvador; Salvador-Palmer, María Rosario; Anda, Rosa María Cibrián-Ortiz de; La O, Javier López-de

    2016-11-01

    Idiopathic scoliosis requires a close follow-up while the patient is skeletally immature to detect early progression. Patients who are monitored by radiographs are exposed to high doses of ionizing radiation. The purpose of this study is to evaluate if an optic noninvasive method of back surface topography based on structured light would be clinically useful in the follow-up of young patients with idiopathic scoliosis. This could reduce the number of radiographs made on these children. Thirty-one patients with idiopathic scoliosis were submitted twice to radiograph and our topographic method at intervals of 6 months to 1 year. Three topographical variables were applied horizontal plane deformity index (DHOPI), posterior trunk symmetry index (POTSI), and columnar profile (PC). A statistically significant correlation was found between variations of Cobb angle with DHOPI (r=0.720, pscoliosis.

  7. Determination of correlation among heart rate variability, left atrium global strain, and nighttime blood pressure among patients with tinnitus.

    Science.gov (United States)

    Değirmenci, Hüsnü; Bakırcı, Eftal Murat; Salcan, İsmail; Demirelli, Selami; Duman, Hakan; Ceyhun, Gökhan; Küçüksu, Zafer

    2014-09-24

    We aimed to examine the correlation among nighttime blood pressure, heart rate variability, and left atrium peak systolic global longitudinal strain among patients with subjective tinnitus. Eighty patients with tinnitus were assigned to Group 1 and 80 healthy individuals were assigned to Group 2. Clinical blood pressure measurements, ambulatory blood pressure monitoring, and Holter electrocardiography monitoring were performed. All of the cases included in the study were examined with conventional echocardiography and 2-dimensional speckle tracking echocardiography. Mean nighttime systolic blood pressure (130.3±5.4) and mean nighttime diastolic blood pressure (82.8±3.9) in Group 1 were higher than in Group 2 (125.1±5.4 and 80.7±4.7, respectively) (pheart rate in Group 1 was significantly lower than in Group 2 but there was no statistically significant difference between the groups in terms of heart rate variability parameters and left atrium peak systolic global longitudinal strain values (p>0.05). Nighttime systolic blood pressure and nighttime diastolic blood pressure were higher among the patients with tinnitus. In light of these results, we can conclude that both clinical blood pressure measurement and ambulatory blood pressure monitoring are important for patients with tinnitus.

  8. RADIO MONITORING OF THE PERIODICALLY VARIABLE IR SOURCE LRLL 54361: NO DIRECT CORRELATION BETWEEN THE RADIO AND IR EMISSIONS

    Energy Technology Data Exchange (ETDEWEB)

    Forbrich, Jan, E-mail: jan.forbrich@univie.ac.at [University of Vienna, Department of Astrophysics, Türkenschanzstraße 17, A-1180 Vienna (Austria); Rodríguez, Luis F.; Palau, Aina; Zapata, Luis A. [Instituto de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán (Mexico); Muzerolle, James [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Gutermuth, Robert A. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)

    2015-11-20

    LRLL 54361 is an infrared source located in the star-forming region IC 348 SW. Remarkably, its infrared luminosity increases by a factor of 10 over roughly one week every 25.34 days. To understand the origin of these remarkable periodic variations, we obtained sensitive 3.3 cm JVLA radio continuum observations of LRLL 54361 and its surroundings in six different epochs: three of them during the IR-on state and three during the IR-off state. The radio source associated with LRLL 54361 remained steady and did not show a correlation with the IR variations. We suggest that the IR is tracing the results of fast (with a timescale of days) pulsed accretion from an unseen binary companion, while the radio traces an ionized outflow with an extent of ∼100 AU that smooths out the variability over a period of the order of a year. The average flux density measured in these 2014 observations, 27 ± 5 μJy, is about a factor of two less than that measured about 1.5 years before, 53 ± 11 μJy, suggesting that variability in the radio is present, but over larger timescales than in the IR. We discuss other sources in the field, in particular two infrared/X-ray stars that show rapidly varying gyrosynchrotron emission.

  9. Temporal variations of NDVI and correlations between NDVI and hydro-climatological variables at Lake Baiyangdian, China

    Science.gov (United States)

    Wang, Fei; Wang, Xuan; Zhao, Ying; Yang, Zhifeng

    2014-09-01

    In this paper, correlations between vegetation dynamics (represented by the normalized difference vegetation index (NDVI)) and hydro-climatological factors were systematically studied in Lake Baiyangdian during the period from April 1998 to July 2008. Six hydro-climatological variables including lake volume, water level, air temperature, precipitation, evaporation, and sunshine duration were used, as well as extracted NDVI series data representing vegetation dynamics. Mann-Kendall tests were used to detect trends in NDVI and hydro-climatological variation, and a Bayesian information criterion method was used to detect their abrupt changes. A redundancy analysis (RDA) was used to determine the major hydro-climatological factors contributing to NDVI variation at monthly, seasonal, and yearly scales. The results were as follows: (1) the trend analysis revealed that only sunshine duration significantly increased over the study period, with an inter-annual increase of 3.6 h/year ( p RDA showed that evaporation and temperature were highly correlated with monthly changes in NDVI. At larger time scales, however, water level and lake volume gradually became more important than evaporation and precipitation in terms of their influence on NDVI. These results suggest that water availability is the most important factor in vegetation restoration. In this paper, we recommend a practical strategy for lake ecosystem restoration that takes into account changes in NDVI.

  10. Unveiling correlations between financial variables and topological metrics of trading networks: Evidence from a stock and its warrant

    Science.gov (United States)

    Li, Ming-Xia; Jiang, Zhi-Qiang; Xie, Wen-Jie; Xiong, Xiong; Zhang, Wei; Zhou, Wei-Xing

    2015-02-01

    Traders develop and adopt different trading strategies attempting to maximize their profits in financial markets. These trading strategies not only result in specific topological structures in trading networks, which connect the traders with the pairwise buy-sell relationships, but also have potential impacts on market dynamics. Here, we present a detailed analysis on how the market behaviors are correlated with the structures of traders in trading networks based on audit trail data for the Baosteel stock and its warrant at the transaction level from 22 August 2005 to 23 August 2006. In our investigation, we divide each trade day into 48 rolling time windows with a length of 5 min, construct a trading network within each window, and obtain a time series of over 11,600 trading networks. We find that there are strongly simultaneous correlations between the topological metrics (including network centralization, assortative index, and average path length) of trading networks that characterize the patterns of order execution and the financial variables (including return, volatility, intertrade duration, and trading volume) for the stock and its warrant. Our analysis may shed new lights on how the microscopic interactions between elements within complex system affect the system's performance.

  11. Effect of temperature on the morphological characteristics of Botrytis cinerea and its correlated with the genetic variability

    Institute of Scientific and Technical Information of China (English)

    Jorge G Fernndez; Martn A Fernndez-Baldo; Gabriela Sansone; Viviana Calvente; Delia Benuzzi; Eloy Salinas; Julio Raba; Mara I Sanz

    2014-01-01

    Objective: To study the effect of temperature on the morphological characteristics of Botrytiscinerea (B. cinerea) and its correlated with the genetic variability. B. cinerea is a plant-pathogenic fungus that produces the disease known as grey mould in a wide variety of agriculturally important hosts in many countries.Methods:Six strains from different host collected have been isolated and characterized by several methods as mycelial growth, fungicide resistance, pathogenicity and the effects of the temperature. Also was analyzed by PCR and distinguished by the presence or absence of transposable elements.Results:Results showed that clear morphological differences exist between strains at the temperature of 4, 12 and 28 °C. All strains analyzed molecularly were classified as Group II (transposa-type). Demonstrating a negative correlation between mycelial growth and other characteristics as the fungicide resistance and pathogenicity. Lastly, it is difficult to establish relationships phenotypic and genotypic between strains of B. cinerea.Conclusions:The results indicated that the mycelial growth, resistance at fungicide and pathogenicity are independent of the characteristics molecular, however, are dependent of a factor such as temperature.

  12. Effect of temperature on the morphological characteristics of Botrytis cinerea and its correlated with the genetic variability

    Directory of Open Access Journals (Sweden)

    Jorge G Fernández

    2014-07-01

    Full Text Available Objective: To study the effect of temperature on the morphological characteristics of Botrytis cinerea (B. cinerea and its correlated with the genetic variability. B. cinerea is a plant-pathogenic fungus that produces the disease known as grey mould in a wide variety of agriculturally important hosts in many countries. Methods: Six strains from different host collected have been isolated and characterized by several methods as mycelial growth, fungicide resistance, pathogenicity and the effects of the temperature. Also was analyzed by PCR and distinguished by the presence or absence of transposable elements. Results: Results showed that clear morphological differences exist between strains at the temperature of 4, 12 and 28 °C. All strains analyzed molecularly were classified as Group II (transposa-type. Demonstrating a negative correlation between mycelial growth and other characteristics as the fungicide resistance and pathogenicity. Lastly, it is difficult to establish relationships phenotypic and genotypic between strains of B. cinerea. Conclusions: The results indicated that the mycelial growth, resistance at fungicide and pathogenicity are independent of the characteristics molecular, however, are dependent of a factor such as temperature.

  13. Correlation of delta high-resolution computed tomography (HRCT) score with delta clinical variables in early systemic sclerosis (SSc) patients

    Science.gov (United States)

    Euathrongchit, Juntima; Wattanawittawas, Pittaporn; Kasitanon, Nuntana

    2016-01-01

    Background The correlation of changes (delta: Δ) of high-resolution computed tomography (HRCT) score with the Δ of other clinical variables has not been well studied. The purpose of this study was to determine the correlation of Δ HRCT score with Δ percent predicted forced vital capacity (%pFVC), Δ modified Rodnan Skin Score (mRSS), Δ erythrocyte sedimentation rate (ESR), and Δ percent of oxygen saturation at room air (%SpO2) in patients with early systemic sclerosis (SSc). Methods We used an inception cohort of early-SSc patients seen at the Rheumatology Clinic, Chiang Mai University, Thailand, between January 2010 and June 2014. All patients underwent HRCT at study entry and every 12 months thereafter. Thirty-one SSc patients who underwent pulmonary function test (PFT) within 12 weeks of their corresponding HRCT at baseline and last visit were identified. The extent of ground glass (GG), lung fibrosis (Fib), bronchiectasis (B), and honeycombing (HC) was scored, and then aggregated to produce a total (t) HRCT score. Results Mean ± SD age and disease duration from non-Raynaud’s phenomenon (NRP) to undergo HRCT at baseline were 52.2±8.8 years and 11.7±7.1 months, respectively. Seventeen (54.8%) patients were female and 20 (64.5%) were classified as dcSSc. The mean ± SD interval between the two HRCT tests was 16.0±7.2 months. The Δ HRCT scores [total fibrosis scores (t-Fib), total bronchiectasis scores (t-B), and total HRCT score (t-HRCT) scores] and Δ mRSS, but not Δ %pFVC, showed significant change over the observation period. We found significant correlation of Δ total honeycombing scores (t-HC) with Δ ESR (r=−0.44, P<0.05), and Δ t-Fib with Δ %SpO2 (r=−0.38, P<0.05). However, no significant correlation of any Δ HRCT scores with Δ %pFVC and Δ mRSS were observed. Conclusions In this study, the changes in the HRCT scores were greater than %pFVC; this, along with their correlations with the changes in ESR and %SpO2, suggest that HRCT

  14. Controlling chaos in balanced neural circuits with input spike trains

    Science.gov (United States)

    Engelken, Rainer; Wolf, Fred

    The cerebral cortex can be seen as a system of neural circuits driving each other with spike trains. Here we study how the statistics of these spike trains affects chaos in balanced target circuits.Earlier studies of chaos in balanced neural circuits either used a fixed input [van Vreeswijk, Sompolinsky 1996, Monteforte, Wolf 2010] or white noise [Lajoie et al. 2014]. We study dynamical stability of balanced networks driven by input spike trains with variable statistics. The analytically obtained Jacobian enables us to calculate the complete Lyapunov spectrum. We solved the dynamics in event-based simulations and calculated Lyapunov spectra, entropy production rate and attractor dimension. We vary correlations, irregularity, coupling strength and spike rate of the input and action potential onset rapidness of recurrent neurons.We generally find a suppression of chaos by input spike trains. This is strengthened by bursty and correlated input spike trains and increased action potential onset rapidness. We find a link between response reliability and the Lyapunov spectrum. Our study extends findings in chaotic rate models [Molgedey et al. 1992] to spiking neuron models and opens a novel avenue to study the role of projections in shaping the dynamics of large neural circuits.

  15. Lung ultrasound in systemic sclerosis: correlation with high-resolution computed tomography, pulmonary function tests and clinical variables of disease.

    Science.gov (United States)

    Gigante, Antonietta; Rossi Fanelli, Filippo; Lucci, Silvio; Barilaro, Giuseppe; Quarta, Silvia; Barbano, Biagio; Giovannetti, Antonello; Amoroso, Antonio; Rosato, Edoardo

    2016-03-01

    Interstitial lung disease (ILD) is a hallmark of systemic sclerosis (SSc). Although high-resolution computed tomography (HRCT) is the gold standard to diagnose ILD, recently lung ultrasound (LUS) has emerged in SSc patients as a new promising technique for the ILD evaluation, noninvasive and radiation-free. The aim of this study was to evaluate if there is a correlation between LUS, chest HRCT, pulmonary function tests findings and clinical variables of the disease. Thirty-nine patients (33 women and 6 men; mean age 51 ± 15.2 years) underwent clinical examination, HRCT, pulmonary function tests and LUS for detection of B-lines. A positive correlation exists between the number of B-lines and the HRCT score (r = 0.81, p < 0.0001), conversely a negative correlation exists between the number of B-lines and diffusing capacity of the lung for carbon monoxide (DLCO) (r = -0.63, p < 0.0001). The number of B-lines increases along with the progression of the capillaroscopic damage. A statistically significant difference in the number of B-lines was found between patients with and without digital ulcers [42 (3-84) vs 16 (4-55)]. We found that the number of B-lines increased with the progression of both HRCT score and digital vascular damage. LUS may therefore, be a useful tool to determine the best timing for HRCT execution, thus, preventing for many patients a continuous and useless exposure to ionizing radiation.

  16. A quantitative correlational investigation of the definition of key decision variables used for the determination of wind energy systems' feasibility

    Science.gov (United States)

    Kelly, Kathleen M.

    Several factors are critical in determining if a wind farm has a high probability of success. These factors include wind energy potential or wind class, sales price, cost of the wind energy generated, market for selling the wind, capacity factor or efficiency of the turbines, capital investment cost, debt and financing, and governmental factors such as taxes and incentives. This research studied the critical factors of thirty-three land based wind farms in the United States with over 20 mega-watts (MW) of capacity that have become operational since 1999. The goal was to develop a simple yet effective decision model using the critical factors to predict an internal rate of return (IRR) and the impact of having a tax credit to supplement the revenue stream. The study found that there are five critical factors that are significantly correlated with the internal rate of return (IRR) of a wind farm project. The critical factors are wind potential or wind class, cost of the wind energy generated, capacity factor or efficiency of the wind turbines, cost of capital investment, and the existence of a federal production tax credit (PTC). The decision model was built using actual wind farm data and industry standards whereby a score from zero to one hundred was coded for each of values except for the production tax credit. Since all the projects qualified for the production tax credit prior to their start up, it was no longer a variable. However, without the presence of this tax credit, the data imply that the projects would not be profitable within the first ten to fifteen years of operation. The scores for each of the categories were totaled and regressed against a calculated internal rate of return. There was ninety-seven percent correlation which was supported by simulation analysis. While this model is not intended to supplant rigorous accounting and financial study, it will help quickly determine if a site has potential and save many hours of analytical work.

  17. Temporal variations of NDVI and correlations between NDVI and hydro-climatological variables at Lake Baiyangdian, China.

    Science.gov (United States)

    Wang, Fei; Wang, Xuan; Zhao, Ying; Yang, Zhifeng

    2014-09-01

    In this paper, correlations between vegetation dynamics (represented by the normalized difference vegetation index (NDVI)) and hydro-climatological factors were systematically studied in Lake Baiyangdian during the period from April 1998 to July 2008. Six hydro-climatological variables including lake volume, water level, air temperature, precipitation, evaporation, and sunshine duration were used, as well as extracted NDVI series data representing vegetation dynamics. Mann-Kendall tests were used to detect trends in NDVI and hydro-climatological variation, and a Bayesian information criterion method was used to detect their abrupt changes. A redundancy analysis (RDA) was used to determine the major hydro-climatological factors contributing to NDVI variation at monthly, seasonal, and yearly scales. The results were as follows: (1) the trend analysis revealed that only sunshine duration significantly increased over the study period, with an inter-annual increase of 3.6 h/year (p < 0.01), whereas inter-annual NDVI trends were negligible; (2) the abrupt change detection showed that a major hydro-climatological change occurred in 2004, when abrupt changes occurred in lake volume, water level, and sunlight duration; and (3) the RDA showed that evaporation and temperature were highly correlated with monthly changes in NDVI. At larger time scales, however, water level and lake volume gradually became more important than evaporation and precipitation in terms of their influence on NDVI. These results suggest that water availability is the most important factor in vegetation restoration. In this paper, we recommend a practical strategy for lake ecosystem restoration that takes into account changes in NDVI.

  18. Interannual Variations in Growing-Season NDVI and Its Correlation with Climate Variables in the Southwestern Karst Region of China

    Directory of Open Access Journals (Sweden)

    Wenjuan Hou

    2015-08-01

    Full Text Available In this study, the updated Global Inventory Modeling and Mapping Studies (GIMMS Normalized Difference Vegetation Index (NDVI dataset for growing season (April to October, which can better reflect the vegetation vigor, was used to investigate the interannual variations in NDVI and its relationship with climatic factors, in order to preliminarily understand the climate impact on vegetation and provide theoretical basis for the response of ecosystem to climate change. Multivariate linear regression models, including the Ordinary Least Squares (OLS and Geographically Weighted Regression (GWR, were adopted to analyze the correlation between NDVI and climatic factors (temperature and precipitation together. Average growing-season NDVI significantly increased at a rate of 0.0015/year from 1982 to 2013, larger than several regions in China. On the whole, its relationship with temperature is positive and also stronger than precipitation, which indicated that temperature may be a limiting factor for the vegetation growth in the Karst region. Moreover, the correlation coefficients between grassland NDVI and climatic factors are the largest. Under the background of NDVI increasing trend from 1982 to 2013, the period of 2009–2012 was chosen to investigate the influencing factors of a sharp decline in NDVI. It can be found that the reduced temperature and solar radiation, caused by the increase in cloud cover and precipitation, may play important roles in the vegetation cover change. All in all, the systematic research on the interannual variations of growing-season NDVI and its relationship with climate revealed the heterogeneity and variability in the complicated climate change in the Karst ecosystem for the study area. It is the Karst characteristics that hinder obtaining more representative conclusions and tendencies in this region. Hence, more attention should be paid to promoting Karst research in the future.

  19. Radio monitoring of the periodically variable IR source LRLL 54361: No direct correlation between the radio and IR emissions

    CERN Document Server

    Forbrich, Jan; Palau, Aina; Zapata, Luis A; Muzerolle, James; Gutermuth, Robert A

    2015-01-01

    LRLL 54361 is an infrared source located in the star forming region IC 348 SW. Remarkably, its infrared luminosity increases by a factor of 10 during roughly one week every 25.34 days. To understand the origin of these remarkable periodic variations, we obtained sensitive 3.3 cm JVLA radio continuum observations of LRLL 54361 and its surroundings in six different epochs: three of them during the IR-on state and three during the IR-off state. The radio source associated with LRLL 54361 remained steady and did not show a correlation with the IR variations. We suggest that the IR is tracing the results of fast (with a timescale of days) pulsed accretion from an unseen binary companion, while the radio traces an ionized outflow with an extent of $\\sim$100 AU that smooths out the variability over a period of order a year. The average flux density measured in these 2014 observations, 27$\\pm$5 $\\mu$Jy, is about a factor of two less than that measured about 1.5 years before, $53\\pm$11 $\\mu$Jy, suggesting that variabi...

  20. Nitrogen loss from high N-input vegetable fields: a) Direct N2O emissions b) Spatiotemporal variability of N species (N2O, NH4+, NO3-) in soils

    Science.gov (United States)

    Palmer, I.; Pfab, H.; Ruser, R.; Fiedler, S.

    2009-04-01

    Nitrous oxide (N2O) is a greenhouse gas contributing to stratospheric ozone depletion. Soils are considered to be the major (70%) source for atmospheric N2O. Agriculture in general accounts for about 85% of the anthropogenic N2O emissions. Whereas 80% of these, are emitted from ag-riculturally used soils. Such estimations of N2O fluxes are associated with a high degree of uncertainties. Uncertainty of source strength estimates mainly results from local scale variability of known and unknown sources. It is not known how much uncertainty is due to unmeasured sources. For example, considerations of N2O fluxes from soils used for intensive vegetable production within inventories are still missing. We speculate that these types of arable soils act as ‚hot spots' for N2O. Given conditions (1) high N-input due to fertilization in concert with (2) easily mineralizable harvest residues should pro-mote disproportional high reaction rates in N-cycling and enhance N2O production as a by-product of nitrification and denitrification. Our investigation focused on the influence of: (1) N-input level (Ammonium Sulfate Nitrate (ASN)) below and above common N doses used for "good agricultural practice". (2) Application of modified fertilizers including nitrification inhibitor DMPP (Dimethylpyrazolphosphate, ENTEC®) and depot fertilization (pseudo-CULTAN) in comparison to non-fertilized control and common ASN application. (3) Effects of plant residues on N-cycling and (4) the deduction of mitigation strategies to reduce the potential N-loss from theses sites. The study was carried out during summer and autumn 2008 on a field cropped with cauliflower, located at the "Heidfeldhof" (South-West Germany; MAT 10.5°C, MAP 660 mm). Three different N-species (N2O; within gaseous soil phase, ammonium (NH4+) and nitrate (NO3-) extracted from bulk soil) were measured weekly in three different soil depths (0-25 cm; 25-50 cm and 50-75 cm) in a fully randomized field design. At same depths water

  1. Facies interpretations and lateral variability based on correlation of conventional core in the Logan canyon and Mississauga formations of the Scotian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Piper, D.J.W. [Geological Survey of Canada (Canada); Gould, K.M.; Pe-Piper, G. [Saint Mary' s University (Canada)], email: 075353g@acadiau.ca

    2011-07-01

    In the Lower Cretaceous of the Scotian Basin in Canada, sediment facies have been interpreted mostly using vertical successions of rock. However, other studies show that the lateral extent and variability of sediment facies must be understood to assess reservoir extent and connectivity. The aim of this paper is to present the investigation of two areas of the Scotian Basin. In each area, a regional correlation was performed using gamma ray well logs and the lithology, sedimentary and biogenic structures were determined for 67 different cores. It was found that the determination of facies and vertical successions was useful for comparing and correlating across multiple wells. In addition it was shown that gamma logs are effective for regional correlation but can only correlate major changes. This paper demonstrated that gamma logs are useful for performing facies interpretations and determining lateral variability.

  2. Total and High Molecular Weight Adiponectin Expression Is Decreased in Patients with Common Variable Immunodeficiency: Correlation with Ig Replacement Therapy

    Directory of Open Access Journals (Sweden)

    Antonio Pecoraro

    2017-07-01

    Full Text Available Adiponectin (Acrp30 is an adipokine widely studied for its beneficial metabolic properties. It circulates as low molecular weight (LMW, medium molecular weight (MMW, and high molecular weight (HMW oligomers. The latter exerts the most potent biological effects. Acrp30 attracted renewed interest with the finding that it was associated with the development and progression of immune disorders. The mechanisms underlying this association and the role of Acrp30 in the pathophysiology of immune-mediated conditions remain unknown. Common variable immunodeficiency (CVID is a primary immunodeficiency characterized by chronic activation of the immune system, impaired antibody production, and imbalanced cytokine production. In the attempt to shed light on the expression of Acrp30 in CVID, we: (a investigated total Acrp30 and its oligomerization state in CVID patients undergoing maintenance Ig replacement therapy; (b assessed the effects of Ig replacement therapy on Acrp30 expression in treatment-naïve CVID patients, namely, patients not treated before diagnosis, before and after the first Ig administration; and (c evaluated the correlation between Acrp30 levels and clinical phenotypes of the disease. As controls, we analyzed healthy subjects and patients affected by a non-immunodeficiency chronic inflammatory demyelinating polyneuropathy (CIDP, before and after Ig infusion. We found that total Acrp30 and HMW oligomers were decreased in CVID but not in CIDP patients versus controls. Moreover, Acrp30 levels were correlated with IgA levels and were associated with two CVID phenotypes, namely, autoimmune cytopenia and enteropathy. Receiver operating characteristic curve analysis indicated that Acrp30 modulation is specific for CVID patients. Acrp30 and HMW levels quickly and dramatically increased after Ig infusion only in eight treatment-naïve CVID patients but not in five CIDP patients. This finding indicates that Ig administration per se is not able to

  3. Queuing model with variable input rates, mistake service and impatient customers%输入率可变且有差错服务及不耐烦顾客的排队模型分析

    Institute of Scientific and Technical Information of China (English)

    潘全如

    2012-01-01

    在系统顾客容量不变的情况下,顾客到达系统后是否进入系统接受服务对销售行业影响是巨大的.从排队长度对顾客输入率的影响着手,研究了输入率、服务正确率及不耐烦顾客强度均与队长有关的排队模型,得出了进入系统的顾客流是泊松过程.系统中的顾客数是生灭过程,同时求得了系统的队长平稳分布,因没有进入系统而导致系统损失的概率、因不耐烦而离去的顾客的均值、单位时间内系统服务错误率、因系统容量有限而无法加入队列的损失概率等多项指标,得出了并非输入率越高系统就盈利越多、并非系统服务正确率越低系统就赚得越少等结论.还得到了能使企业利润最大化的系统容量及服务速度,为销售行业提高自己的销售业绩提供了很有价值的参考.%The customers do not necessarily get into the system though arriving at it in the case of a fixed customer number, which influences sales industry enormously. Focusing on the influence of queue length on input rate, we build up a queuing model with variable input rates,mistake service and impatient customers, and draw the following conclusions; the customers get into the system in Poissonian flow; the number of customers in the system is a birth-death process. We obtained the stationary queue length distribution of the model, the loss probability for the customers not entering the system while arriving at the system, the mean of the customers who leaves the system due to impatience, the service error rate per unit time and the loss probability for the customers not joining the queue due to the limited capacity of the system and so on. This paper also justifies the falsehood of the following assumptions: the bigger the input rate is, the more profit business will get; the bigger the number of impatient customers is, the less profit business will make. We also obtaind the appropriate service speed and capacity a

  4. Correlation between the Lactate Dehydrogenase Levels with Laboratory Variables in the Clinical Severity of Sickle Cell Anemia in Congolese Patients.

    Directory of Open Access Journals (Sweden)

    Tite Minga Mikobi

    Full Text Available Sickle cell anemia is an inflammatory disease and is characterized by chronic hemolysis. We sought to evaluate the association of lactate dehydrogenase levels with specific clinical phenotypes and laboratory variables in patients with sickle cell anemia.The present cross-sectional study was conducted in Sickle Cell Centre of Yolo in Kinshasa, the Democratic Republic of Congo. Two hundred and eleven patients with Sickle Cell Anemia in steady state were recruited. Seventy-four participants with normal Hb (Hb-AA were selected as a control group.The average rates of hemoglobin, hematocrit, and red blood cells tended to be significantly lower in subjects with Hb-SS (p<0.001. The average rates of white blood cells, platelets, reticulocytes and serum LDH were significantly higher in subjects with Hb-SS (p<0.001. The average rates of Hb, HbF, hematocrit and red blood cells of Hb-SS patients with asymptomatic clinical phenotype were significantly higher than those of the two other phenotypes. However, the average rates of white blood cells, platelets, reticulocytes, and LDH of Hb-SS patients with the severe clinical phenotype are higher than those of two other clinical phenotypes. Significant correlations were observed between Hb and white blood cell in severe clinical phenotype (r3 = -0.37 * between Hb and red blood cells in the three phenotypes (r1 = 0.69 * r2 * = 0.69, r3 = 0.83 *, and finally between Hb and reticulocytes in the asymptomatic clinical phenotype and severe clinical phenotype (r1 = -0.50 * r3 = 0.45 *. A significant increase in LDH was observed in patients with leg ulcer, cholelithiasis and aseptic necrosis of the femoral head.The increase in serum LDH is accompanied by changes in hematological parameters. In our midst, serum LDH may be considered as an indicator of the severity of the disease.

  5. Correlation between the Lactate Dehydrogenase Levels with Laboratory Variables in the Clinical Severity of Sickle Cell Anemia in Congolese Patients

    Science.gov (United States)

    Mikobi, Tite Minga; Lukusa Tshilobo, Prosper; Aloni, Michel Ntetani; Mvumbi Lelo, Georges; Akilimali, Pierre Zalagile; Muyembe-Tamfum, Jean Jacques; Race, Valérie; Matthijs, Gert; Mbuyi Mwamba, Jean Marie

    2015-01-01

    Background Sickle cell anemia is an inflammatory disease and is characterized by chronic hemolysis. We sought to evaluate the association of lactate dehydrogenase levels with specific clinical phenotypes and laboratory variables in patients with sickle cell anemia. Methods The present cross-sectional study was conducted in Sickle Cell Centre of Yolo in Kinshasa, the Democratic Republic of Congo. Two hundred and eleven patients with Sickle Cell Anemia in steady state were recruited. Seventy-four participants with normal Hb (Hb-AA) were selected as a control group. Results The average rates of hemoglobin, hematocrit, and red blood cells tended to be significantly lower in subjects with Hb-SS (p<0.001). The average rates of white blood cells, platelets, reticulocytes and serum LDH were significantly higher in subjects with Hb-SS (p<0.001). The average rates of Hb, HbF, hematocrit and red blood cells of Hb-SS patients with asymptomatic clinical phenotype were significantly higher than those of the two other phenotypes. However, the average rates of white blood cells, platelets, reticulocytes, and LDH of Hb-SS patients with the severe clinical phenotype are higher than those of two other clinical phenotypes. Significant correlations were observed between Hb and white blood cell in severe clinical phenotype (r3 = -0.37 *) between Hb and red blood cells in the three phenotypes (r1 = 0.69 * r2 * = 0.69, r3 = 0.83 *), and finally between Hb and reticulocytes in the asymptomatic clinical phenotype and severe clinical phenotype (r1 = -0.50 * r3 = 0.45 *). A significant increase in LDH was observed in patients with leg ulcer, cholelithiasis and aseptic necrosis of the femoral head. Conclusion The increase in serum LDH is accompanied by changes in hematological parameters. In our midst, serum LDH may be considered as an indicator of the severity of the disease. PMID:25946088

  6. Two-dimensional correlation spectroscopy (2D-COS) variable selection for near-infrared microscopy discrimination of meat and bone meal in compound feed.

    Science.gov (United States)

    Lü, Chengxu; Chen, Longjian; Yang, Zengling; Liu, Xian; Han, Lujia

    2014-01-01

    This article presents a novel method for combining auto-peak and cross-peak information for sensitive variable selection in synchronous two-dimensional correlation spectroscopy (2D-COS). This variable selection method is then applied to the case of near-infrared (NIR) microscopy discrimination of meat and bone meal (MBM). This is of important practical value because MBM is currently banned in ruminate animal compound feed. For the 2D-COS analysis, a set of NIR spectroscopy data of compound feed samples (adulterated with varying concentrations of MBM) was pretreated using standard normal variate and detrending (SNVD) and then mapped to the 2D-COS synchronous matrix. For the auto-peak analysis, 12 main sensitive variables were identified at 6852, 6388, 6320, 5788, 5600, 5244, 4900, 4768, 4572, 4336, 4256, and 4192 cm(-1). All these variables were assigned their specific spectral structure and chemical component. For the cross-peak analysis, these variables were divided into two groups, each group containing the six sensitive variables. This grouping resulted in a correlation between the spectral variables that was in accordance with the chemical-component content of the MBM and compound feed. These sensitive variables were then used to build a NIR microscopy discrimination model, which yielded a 97% correct classification. Moreover, this method detected the presence of MBM when its concentration was less than 1% in an adulterated compound feed sample. The concentration-dependent 2D-COS-based variable selection method developed in this study has the unique advantages of (1) introducing an interpretive aspect into variable selection, (2) substantially reducing the complexity of the computations, (3) enabling the transferability of the results to discriminant analysis, and (4) enabling the efficient compression of spectral data.

  7. Detecting correlation between allele frequencies and environmental variables as a signature of selection. A fast computational approach for genome-wide studies

    DEFF Research Database (Denmark)

    Guillot, Gilles; Vitalis, Renaud; Rouzic, Arnaud le;

    2014-01-01

    Genomic regions (or loci) displaying outstanding correlation with some environmental variables are likely to be under selection and this is the rationale of recent methods of identifying selected loci and retrieving functional information about them. To be efficient, such methods need to be able...... to disentangle the potential effect of environmental variables from the confounding effect of population history. For the routine analysis of genome-wide datasets, one also needs fast inference and model selection algorithms. We propose a method based on an explicit spatial model which is an instance of spatial...... generalized linear mixed model (SGLMM). For inference, we make use of the INLA–SPDE theoretical and computational framework developed by Rue et al. (2009) and Lindgren et al. (2011). The method we propose allows one to quantify the correlation between genotypes and environmental variables. It works...

  8. Does heart rate variability correlate with long-term prognosis in myocardial infarction patients treated by early revascularization?

    Science.gov (United States)

    Compostella, Leonida; Lakusic, Nenad; Compostella, Caterina; Truong, Li Van Stella; Iliceto, Sabino; Bellotto, Fabio

    2017-01-01

    AIM To assess the prevalence of depressed heart rate variability (HRV) after an acute myocardial infarction (MI), and to evaluate its prognostic significance in the present era of immediate reperfusion. METHODS Time-domain HRV (obtained from 24-h Holter recordings) was assessed in 326 patients (63.5 ± 12.1 years old; 80% males), two weeks after a complicated MI treated by early reperfusion: 208 ST-elevation myocardial infarction (STEMI) patients (in which reperfusion was successfully obtained within 6 h of symptoms in 94% of cases) and 118 non-ST-elevation myocardial infarction (NSTEMI) patients (percutaneous coronary intervention was performed within 24 h and successful in 73% of cases). Follow-up of the patients was performed via telephone interviews a median of 25 mo after the index event (95%CI of the mean 23.3-28.0). Primary end-point was occurrence of all-cause or cardiac death; secondary end-point was occurrence of major clinical events (MCE, defined as mortality or readmission for new MI, new revascularization, episodes of heart failure or stroke). Possible correlations between HRV parameters (mainly the standard deviation of all normal RR intervals, SDNN), clinical features (age, sex, type of MI, history of diabetes, left ventricle ejection fraction), angiographic characteristics (number of coronary arteries with critical stenoses, success and completeness of revascularization) and long-term outcomes were analysed. RESULTS Markedly depressed HRV parameters were present in a relatively small percentage of patients: SDNN 2 years from infarction, a total of 10 patients (3.1%) were lost to follow-up. Overall incidence of MCE at follow-up was similar between STEMI and NSTEMI (P = 0.141), although all-cause and cardiac mortality were higher among NSTEMI cases (respectively: 14% vs 2%, P = 0.001; and 10% vs 1.5%, P = 0.001). The Kaplan-Meier survival curves for all-cause mortality and for cardiac deaths did not reveal significant differences between patients

  9. Variabilidade espacial de atributos químicos de um argissolo para aplicação de insumos à taxa variável em diferentes formas de relevo Spatial variability of chemical attributes in an alfisol for variable rates of inputs in different forms of relief

    Directory of Open Access Journals (Sweden)

    Diogo M. Barbieri

    2008-12-01

    Full Text Available A agricultura de precisão implica análise da variabilidade espacial de fatores de produção e a aplicação de insumos de forma localizada. Várias são as causas que condicionam a variabilidade espacial dos solos, sendo o relevo um dos fatores mais importantes. O presente estudo teve por objetivo analisar a variabilidade espacial dos atributos químicos do solo e a elaboração de mapas de necessidade de aplicação de insumos de forma localizada, em áreas com diferentes formas de relevo. Duas parcelas de 1 ha cada foram delimitadas em áreas com topografia côncava e convexa. Foram retiradas, em cada área, 242 amostras de solos em 121 pontos, nas profundidades de solo de 0,00-0,20 m e 0,20-0,40 m. Os resultados de análise química foram submetidos às análises da estatística descritiva, geoestatística e interpolação por krigagem. A área convexa apresentou maior variabilidade espacial do solo em relação a área côncava. A adoção da agricultura de precisão possibilitou economia de aproximadamente 25 kg ha-1 de P2O5 na área côncava.The precision agriculture implies an analysis of spatial variability of production factors and the inputs application of located form. There are several factors that cause spatial variability in soils; relief is one of the most important ones. The objective of this study was to analyze the spatial variability, the chemical attributes of the soil and the elaboration of maps necessity for input application of located form, in areas with different relief forms. Two parcels of one hectare each were delimited in areas with concave and convex shaped topography. A set of 242 samples were collected from each area at 121 points in depths of 0.00-0.20 m and 0.20-0.40 m. The data were submitted to the descriptive statistical analyses, geostatistics and interpolation for kriging. The convex area presented more spatial variability of the soil in relation the concave area. The adoption of precision agriculture

  10. Seasonal and interannual variability of sedimentation and organic matter distribution in the Buor-Khaya Gulf: the primary recipient of input from Lena River and coastal erosion in the southeast Laptev Sea

    Directory of Open Access Journals (Sweden)

    A. N. Charkin

    2011-09-01

    Full Text Available Climate warming is amplified in the land-sea system of the East Siberian Arctic, which also holds large pools of vulnerable carbon in permafrost. This coastal area is strongly influenced by sediment and carbon transport from both its large rivers and extensive erosion of Pleistocene permafrost along its coastline. This study is investigating the coastal fate of the sediment and organic carbon delivered to the Buor-Khaya Gulf, which is the first recipient of the overwhelming fluvial discharge from the Lena River and is additionally receiving large input from extensive erosion of the coastal ice-complex (permafrost a.k.a. Yedoma; loess soil with high organic carbon content. Both water column suspended particulate matter (SPM and surface sediments were sampled at about 250 oceanographic stations in the Gulf in this multi-year effort, including one winter campaign, and analyzed for the distribution and sorting of sediment size, organic carbon content, and stable carbon isotope signals. The composition of the surface sediment suggests an overwhelmingly terrestrial contribution from both river and coastal erosion. The objective of this paper is to improve our understanding of the seasonal (i.e., winter vs summer and interannual variability of these coastal sedimentation processes and the dynamics of organic carbon (OC distribution in both the water column SPM and the surface sediments of the Buor-Khaya Gulf.

    Based on data collected during several years in the period 2000–2008, two different sedimentation regimes were revealed for the Buor-Khaya Gulf, the relative importance of each at a given time depend on hydrometeorological conditions, the Lena River water discharge and sea-ice regime: Type 1 erosion-accumulation and Type 2 accumulation.

    The Type 1 erosion-accumulation sedimentation regime is typical (2000–2006 for the ice-free period of the year (here considered in detail for August 2005. Under such conditions terrigenous

  11. Coefficient of variation of R-R interval closely correlates with glycemic variability assessed by continuous glucose monitoring in insulin-depleted patients with type 1 diabetes.

    Science.gov (United States)

    Iwasaki, Shingo; Kozawa, Junji; Fukui, Kenji; Iwahashi, Hiromi; Imagawa, Akihisa; Shimomura, Iichiro

    2015-08-01

    In type 1 diabetic patients, insulin secretory capacity, meals and physical activity correlate with glycemic variability. Autonomic function associated with gastrointestinal motility and counterregulatory hormone secretion is another candidate which correlates with glucose variability. The aim of this study is to clarify a new clinical parameter associated with glycemic variability in insulin-depleted patients with type 1 diabetes. We studied 31 inpatients with type 1 diabetes. We evaluated glycemic variability calculated by continuous glucose monitoring, clinical parameters and the coefficient of variation of R-R interval (CVR-R). Glycemic variability was also assessed during the daytime and nighttime. The CVR-R showed a significant negative correlation with the whole-day standard deviation (SD) (r = -0.50, p = 0.007), mean amplitude of glycemic excursions (MAGE) (r = -0.47, p=0.011), M-value (r = -0.38, p = 0.048) and mean of daily differences (MODD) (r = -0.59, p = 0.001). The CVR-R also showed a significant negative correlation with the nighttime SD (r = -0.59, p = 0.001), MAGE (r = -0.47, p=0.011), M-value (r = -0.53, p = 0.004) and MODD (r = -0.65, p = 0.0003). And furthermore, the CVR-R also showed a significant negative correlation with the daytime SD (r = -0.44, p = 0.019) and MAGE (r = -0.50, p = 0.006), but not with the daytime M-value or MODD. The nighttime SD was significantly higher in patients with diabetic polyneuropathy than in patients without it (p = 0.016), while the CVR-R was significantly lower in patients with polyneuropathy than in patients without it (p = 0.009). CVR-R is closely correlated with glycemic variability, especially during nighttime, in insulin-depleted patients with type 1 diabetes. Measuring CVR-R may help us to presume the degree of glycemic variability in those patients. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71, III. Rapid and correlated flux density variability from radio to sub-mm bands

    CERN Document Server

    Fuhrmann, L; Witzel, A; Kraus, A; Britzen, S; Bernhart, S; Impellizzeri, C M V; Agudo, I; Klare, J; Sohn, B W; Angelakis, E; Bach, U; Gab'anyi, K 'E; K"ording, E; Pagels, A; Zensus, J A; Wagner, S J; Ostorero, L; Ungerechts, H; Grewing, M; Tornikoski, M; Apponi, A J; Vila-Vilar'o, B; Ziurys, L M; Strom, R G

    2008-01-01

    The BL Lac object S5 0716+71 was observed in a global multi-frequency campaign to search for rapid and correlated flux density variability and signatures of an inverse-Compton (IC) catastrophe during the states of extreme apparent brightness temperatures. The observing campaign involved simultaneous monitoring at radio to IR/optical wavelengths centered around a 500-ks INTEGRAL pointing (November 10-17, 2003). We present the combined analysis and results of the cm- to sub-mm observations including a detailed study of the inter- to intra-day variability and spectral characteristics of 0716+714. We further constrain the variability brightness temperatures (T_B) and Doppler factors (delta) comparing the radio-bands with the hard X-ray emission (3-200 keV). 0716+714 was in an exceptionally high state (outburst) and different (slower) phase of short-term variability. The flux density variability in the cm- to mm-bands is dominated by a correlated, ~4 day time scale amplitude increase of up to ~35% systematically m...

  13. ColloInputGenerator

    DEFF Research Database (Denmark)

    2013-01-01

    This is a very simple program to help you put together input files for use in Gries' (2007) R-based collostruction analysis program. It basically puts together a text file with a frequency list of lexemes in the construction and inserts a column where you can add the corpus frequencies. It requires...... it as input for basic collexeme collostructional analysis (Stefanowitsch & Gries 2003) in Gries' (2007) program. ColloInputGenerator is, in its current state, based on programming commands introduced in Gries (2009). Projected updates: Generation of complete work-ready frequency lists....

  14. Spike Triggered Covariance in Strongly Correlated Gaussian Stimuli

    Science.gov (United States)

    Aljadeff, Johnatan; Segev, Ronen; Berry, Michael J.; Sharpee, Tatyana O.

    2013-01-01

    Many biological systems perform computations on inputs that have very large dimensionality. Determining the relevant input combinations for a particular computation is often key to understanding its function. A common way to find the relevant input dimensions is to examine the difference in variance between the input distribution and the distribution of inputs associated with certain outputs. In systems neuroscience, the corresponding method is known as spike-triggered covariance (STC). This method has been highly successful in characterizing relevant input dimensions for neurons in a variety of sensory systems. So far, most studies used the STC method with weakly correlated Gaussian inputs. However, it is also important to use this method with inputs that have long range correlations typical of the natural sensory environment. In such cases, the stimulus covariance matrix has one (or more) outstanding eigenvalues that cannot be easily equalized because of sampling variability. Such outstanding modes interfere with analyses of statistical significance of candidate input dimensions that modulate neuronal outputs. In many cases, these modes obscure the significant dimensions. We show that the sensitivity of the STC method in the regime of strongly correlated inputs can be improved by an order of magnitude or more. This can be done by evaluating the significance of dimensions in the subspace orthogonal to the outstanding mode(s). Analyzing the responses of retinal ganglion cells probed with Gaussian noise, we find that taking into account outstanding modes is crucial for recovering relevant input dimensions for these neurons. PMID:24039563

  15. Spike triggered covariance in strongly correlated gaussian stimuli.

    Directory of Open Access Journals (Sweden)

    Johnatan Aljadeff

    Full Text Available Many biological systems perform computations on inputs that have very large dimensionality. Determining the relevant input combinations for a particular computation is often key to understanding its function. A common way to find the relevant input dimensions is to examine the difference in variance between the input distribution and the distribution of inputs associated with certain outputs. In systems neuroscience, the corresponding method is known as spike-triggered covariance (STC. This method has been highly successful in characterizing relevant input dimensions for neurons in a variety of sensory systems. So far, most studies used the STC method with weakly correlated Gaussian inputs. However, it is also important to use this method with inputs that have long range correlations typical of the natural sensory environment. In such cases, the stimulus covariance matrix has one (or more outstanding eigenvalues that cannot be easily equalized because of sampling variability. Such outstanding modes interfere with analyses of statistical significance of candidate input dimensions that modulate neuronal outputs. In many cases, these modes obscure the significant dimensions. We show that the sensitivity of the STC method in the regime of strongly correlated inputs can be improved by an order of magnitude or more. This can be done by evaluating the significance of dimensions in the subspace orthogonal to the outstanding mode(s. Analyzing the responses of retinal ganglion cells probed with [Formula: see text] Gaussian noise, we find that taking into account outstanding modes is crucial for recovering relevant input dimensions for these neurons.

  16. The Generalization of Mutual Information as the Information between a Set of Variables: The Information Correlation Function Hierarchy and the Information Structure of Multi-Agent Systems

    Science.gov (United States)

    Wolf, David R.

    2004-01-01

    The topic of this paper is a hierarchy of information-like functions, here named the information correlation functions, where each function of the hierarchy may be thought of as the information between the variables it depends upon. The information correlation functions are particularly suited to the description of the emergence of complex behaviors due to many- body or many-agent processes. They are particularly well suited to the quantification of the decomposition of the information carried among a set of variables or agents, and its subsets. In more graphical language, they provide the information theoretic basis for understanding the synergistic and non-synergistic components of a system, and as such should serve as a forceful toolkit for the analysis of the complexity structure of complex many agent systems. The information correlation functions are the natural generalization to an arbitrary number of sets of variables of the sequence starting with the entropy function (one set of variables) and the mutual information function (two sets). We start by describing the traditional measures of information (entropy) and mutual information.

  17. How to regress and predict in a Bland-Altman plot? Review and contribution based on tolerance intervals and correlated-errors-in-variables models.

    Science.gov (United States)

    Francq, Bernard G; Govaerts, Bernadette

    2016-06-30

    Two main methodologies for assessing equivalence in method-comparison studies are presented separately in the literature. The first one is the well-known and widely applied Bland-Altman approach with its agreement intervals, where two methods are considered interchangeable if their differences are not clinically significant. The second approach is based on errors-in-variables regression in a classical (X,Y) plot and focuses on confidence intervals, whereby two methods are considered equivalent when providing similar measures notwithstanding the random measurement errors. This paper reconciles these two methodologies and shows their similarities and differences using both real data and simulations. A new consistent correlated-errors-in-variables regression is introduced as the errors are shown to be correlated in the Bland-Altman plot. Indeed, the coverage probabilities collapse and the biases soar when this correlation is ignored. Novel tolerance intervals are compared with agreement intervals with or without replicated data, and novel predictive intervals are introduced to predict a single measure in an (X,Y) plot or in a Bland-Atman plot with excellent coverage probabilities. We conclude that the (correlated)-errors-in-variables regressions should not be avoided in method comparison studies, although the Bland-Altman approach is usually applied to avert their complexity. We argue that tolerance or predictive intervals are better alternatives than agreement intervals, and we provide guidelines for practitioners regarding method comparison studies. Copyright © 2016 John Wiley & Sons, Ltd.

  18. Correlation between heart rate variability and pupillary reflex in healthy adult subjects under the influence of alcohol

    Institute of Scientific and Technical Information of China (English)

    Jin Ma; Rumeng Ma; Xiwen Liu; Zhihong Wen; Xiaojing Li; Tao Wang; Wenqiang Han; Wendong Hu; Zuoming Zhang

    2011-01-01

    This study explored the association between pupil area variation, heart rate variability, and fatigue, caused by alcohol consumption. Sixteen healthy young male volunteers were enrolled in this study for a series of structured physical examinations. Individual drinking volume was strictly assessed in accordance with the normalized experimental design. The motions of the subjects' pupils, as well as electrocardiograms were recorded by a computerized recording system, both before and after drinking alcohol. After alcohol intake, the pupil diameter, and both low frequency and standard deviation of all heartbeat interval indices of heart rate variability showed significant variations compared with the baseline. In addition, time- and frequency-domain indices of heart rate variability were negatively associated with pupil area. Thus the current study suggests that fatigue status may be determined by significant changes in pupil area and heart rate variability.

  19. Nitrogen loss from high N-input vegetable fields - a) direct N2O emissions b) Spatiotemporal variability of N species (N2O, NH4+, NO3-) in soils

    Science.gov (United States)

    Pfab, H.; Ruser, R.; Palmer, I.; Fiedler, S.

    2009-04-01

    Nitrous oxide is a climate relevant trace gas. It contributes 7.9 % to the total anthropogenic greenhouse gas emission and it is also involved in stratospheric ozone depletion. Approximately 85 % of the anthropogenic N2O emissions result from agricultural activities, more than 50 % are produced during microbial N-turnover processes in soils. Especially soils with high N-input (N-fertilizer and high amount of N in plant residues) like vegetable cropped soils are assumed to cause high N2O losses. The aims of the study presented were (i) to quantify the N2O loss from a vegetable field (lettuce-cauliflower crop rotation), (ii) to calculate an emission factor for the study site in Southwest Germany and to compare this factor with the default value provided by the IPCC (2006) and (iii) to test the emission reduction potential (Ammonium Sulfate Nitrate fertilizer, ASN either by reduced N-fertilization) in comparison with common N doses used for good agricultural practice or by the use of a nitrification inhibitor (DMPP), a banded N-application (lettuce) or a depot fertilization measure (pseudo-CULTAN in order to suppress nitrification). N2O fluxes determined with the closed chamber method were highly variable in time with strongly increased flux rates after N-fertilization in combination with rainfall or irrigation measures and after the incorporation of cauliflower crop residues. Using the mean soil nitrate contents of the top soil of our investigated treatments (0-25 cm depth), we could explain approximately 60 % of the variability of the cumulative N2O losses during the vegetation period of lettuce and cauliflower. The cumulative N2O emissions ranged between 0,99 kg N2O-N ha-1 from the unfertilized control plots (vegetation period) and 6,81 kg N2O-N ha-1 from the plots with the highest N-dose. Based on the guidelines of the IPCC (2006), we calculated an emission factor around 0,9 % for the cropping season. This value is in good agreement with the default value of the

  20. Magnetic resonance observation of cartilage repair tissue (MOCART) for the evaluation of autologous chondrocyte transplantation: Determination of interobserver variability and correlation to clinical outcome after 2 years

    Energy Technology Data Exchange (ETDEWEB)

    Marlovits, Stefan [Department of Traumatology, Center for Joint and Cartilage, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria)]. E-mail: stefan.marlovits@meduniwien.ac.at; Singer, Philipp [Department of Traumatology, Center for Joint and Cartilage, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Zeller, Philip [Department of Traumatology, Center for Joint and Cartilage, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Mandl, Irena [Department of Traumatology, Center for Joint and Cartilage, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria); Haller, Joerg [Department of Radiology, Hanusch Hospital, Heinrich-Collin-Strasse, A-1140 Vienna (Austria); Trattnig, Siegfried [Department of Radiology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna (Austria)

    2006-01-15

    In an observational study, the validity and reliability of magnetic resonance imaging (MRI) for the assessment of autologous chondrocyte transplantation (ACT) in the knee joint was determined. Two years after implantation, high-resolution MRI was used to analyze the repair tissue with nine pertinent variables. A complete filling of the defect was found in 61.5%, and a complete integration of the border zone to the adjacent cartilage in 76.9%. An intact subchondral lamina was present in 84.6% and an intact subchondral bone was present in 61.5%. Isointense signal intensities of the repair tissue compared to the adjacent native cartilage were seen in 92.3%. To evaluate interobserver variability, a reliability analysis with the determination of the intraclass correlation coefficient (ICC) was calculated. An 'almost perfect' agreement, with an ICC value >0.81, was calculated in 8 of 9 variables. The clinical outcome after 2 years showed the visual analog score (VAS) at 2.62 (S.D. {+-}0.65). The values for the knee injury and osteoarthritis outcome score (KOOS) subgroups were 68.29 ({+-}23.90) for pain, 62.09 ({+-}14.62) for symptoms, 75.45 ({+-}21.91) for ADL function, 52.69 ({+-}28.77) for sport and 70.19 ({+-}22.41) for knee-related quality of life. The clinical scores were correlated with the MRI variables. A statistically significant correlation was found for the variables 'filling of the defect,' 'structure of the repair tissue,' 'changes in the subchondral bone,' and 'signal intensities of the repair issue'. High resolution MRI and well-defined MRI variables are a reliable, reproducible and accurate tool for assessing cartilage repair tissue.

  1. Quantification of leptin in seminal plasma of buffalo bulls and its correlation with antioxidant status, conventional and computer-assisted sperm analysis (CASA) semen variables.

    Science.gov (United States)

    Kumar, Pradeep; Saini, Monika; Kumar, Dharmendra; Jan, M H; Swami, Dheer Singh; Sharma, R K

    2016-03-01

    The present study is the first to quantify leptin in seminal plasma of buffalo and investigate its relationship with seminal attributes. Ten ejaculates each from 10 Murrah buffalo bulls were collected. Semen quality variables such as semen volume, sperm concentration, sperm abnormalities, membrane integrity, antioxidant enzyme activities (superoxide dismutase, catalase and total antioxidant capacity), malondialdehyde (MDA) concentration, as well as sperm kinetics and motility variables were evaluated. The leptin concentration in serum and seminal plasma were estimated by the ELISA method. Bulls were classified in two groups on the basis of sperm concentration with Group I having >800 million sperm/mL and Group II <500 million sperm/mL. Greater (P<0.05) mean sperm abnormalities, seminal leptin concentrations and MDA concentrations were recorded in Group II than Group I. The seminal leptin was positively correlated with sperm abnormalities and MDA concentration while being negatively correlated with sperm concentration, but there was no correlation with sperm kinetic and motility variables, sperm membrane integrity and seminal plasma antioxidant enzyme activity. Thus, the data suggest that seminal leptin has a role in spermatogenesis and can be used as a marker for spermatogenesis to predict the capacity of buffalo bulls for semen production. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Limit distributions of scale-invariant probabilistic models of correlated random variables with the q-Gaussian as an explicit example

    Science.gov (United States)

    Hanel, R.; Thurner, S.; Tsallis, C.

    2009-11-01

    Extremization of the Boltzmann-Gibbs (BG) entropy S_{BG}=-kint dx p(x) ln p(x) under appropriate norm and width constraints yields the Gaussian distribution pG(x) ∝e-βx. Also, the basic solutions of the standard Fokker-Planck (FP) equation (related to the Langevin equation with additive noise), as well as the Central Limit Theorem attractors, are Gaussians. The simplest stochastic model with such features is N ↦∞ independent binary random variables, as first proved by de Moivre and Laplace. What happens for strongly correlated random variables? Such correlations are often present in physical situations as e.g. systems with long range interactions or memory. Frequently q-Gaussians, pq(x) ∝[1-(1-q)βx2]1/(1-q) [p1(x)=pG(x)] become observed. This is typically so if the Langevin equation includes multiplicative noise, or the FP equation to be nonlinear. Scale-invariance, e.g. exchangeable binary stochastic processes, allow a systematical analysis of the relation between correlations and non-Gaussian distributions. In particular, a generalized stochastic model yielding q-Gaussians for all (q ≠ 1) was missing. This is achieved here by using the Laplace-de Finetti representation theorem, which embodies strict scale-invariance of interchangeable random variables. We demonstrate that strict scale invariance together with q-Gaussianity mandates the associated extensive entropy to be BG.

  3. Simultaneous Multi-Wavelength Observations of the TeV Blazar Mrk 421 during February - March, 2003: X-Ray and NIR Correlated Variability

    Institute of Scientific and Technical Information of China (English)

    Alok C. Gupta; B. S. Acharya; Debanjan Bose; Varsha R. Chitnis; Jun-Hui Fan

    2008-01-01

    We report the result of simultaneous multi-wavelength observations of the TeV blazar Mrk 421 during February - March 2003. We observed Mrk 421 using the Pachmarhi Array of Cerenkov Telescopes (PACT) of Tata Institute of Fundamental Research at Pachmarhi, India. Other simultaneous data were taken from the literature and public data archives. We have analyzed the high quality X-ray (2-20keV) observations from the NASA Rossi X-Ray Timing Explorer (RXTE). We obtained a possible correlated variability between X-ray and J band (1.25 μ) near infrared (NIR) wavelength. This is the first case of X-ray and NIR correlated variability in Mrk 421 or any high energy peaked (HBL) blazar. The correlated variability reported here indicates a similar origin for the NIR and X-ray emissions. The emission is not affected much by the environment of the surrounding medium of the central engine of Mrk 421. The observations are consistent with the shock-in-jet model for the emissions.

  4. Simultaneous multi-wavelength observations of the TeV Blazar Mrk 421 during February - March 2003: X-ray and NIR correlated variability

    CERN Document Server

    Gupta, Alok C; Bose, Debanjan; Chitnis, Varsha R; Fan, Jun-Hui

    2008-01-01

    In the present paper, we have reported the result of simultaneous multi-wavelength observations of the TeV blazar Mrk 421 during February $-$ March 2003. In this period, we have observed Mrk 421 using Pachmarhi Array of \\v{C}erenkov Telescopes (PACT) of Tata Institute of Fundamental Research at Pachmarhi, India. Other simultaneous data were taken from the published literature and public data archives. We have analyzed the high quality X-ray (2-20 keV) observations from the NASA Rossi X-Ray Timing Explorer (RXTE). We have seen a possible correlated variability between X-ray and J band (1.25 $\\mu$) near infrared (NIR) wavelength. This is the first case of X-ray and NIR correlated variability in Mrk 421 or any high energy peaked (HBL) blazar. The correlated variability reported here is indicating a similar origin for NIR and X-ray emission. The emission is not affected much by the environment of the surrounding medium around the central engine of the Mrk 421. The observations are consistent with the shock-in-jet...

  5. Grading Crohn disease activity with MRI: interobserver variability of MRI features, MRI scoring of severity, and correlation with Crohn disease endoscopic index of severity.

    Science.gov (United States)

    Tielbeek, Jeroen A W; Makanyanga, Jesica C; Bipat, Shandra; Pendsé, Doug A; Nio, C Yung; Vos, Frans M; Taylor, Stuart A; Stoker, Jaap

    2013-12-01

    The purpose of this article is to assess the interobserver variability for scoring MRI features of Crohn disease activity and to correlate two MRI scoring systems to the Crohn disease endoscopic index of severity (CDEIS). Thirty-three consecutive patients with Crohn disease undergoing 3-T MRI examinations (T1-weighted with IV contrast medium administration and T2-weighted sequences) and ileocolonoscopy within 1 month were independently evaluated by four readers. Seventeen MRI features were recorded in 143 bowel segments and were used to calculate the MR index of activity and the Crohn disease MRI index (CDMI) score. Multirater analysis was performed for all features and scoring systems using intraclass correlation coefficient (icc) and kappa statistic. Scoring systems were compared with ileocolonoscopy with CDEIS using Spearman rank correlation. Thirty patients (median age, 32 years; 21 women and nine men) were included. MRI features showed fair-to-good interobserver variability (intraclass correlation coefficient or kappa varied from 0.30 to 0.69). Wall thickness in millimeters, presence of edema, enhancement pattern, and length of the disease in each segment showed a good interobserver variability between all readers (icc = 0.69, κ = 0.66, κ = 0.62, and κ = 0.62, respectively). The MR index of activity and CDMI scores showed good reproducibility (icc = 0.74 and icc = 0.78, respectively) and moderate CDEIS correlation (r = 0.51 and r = 0.59, respectively). The reproducibility of individual MRI features overall is fair to good, with good reproducibility for the most commonly used features. When combined into the MR index of activity and CDMI score, overall reproducibility is good. Both scores show moderate agreement with CDEIS.

  6. Engineering correlations of variable-property effects on laminar forced convection mass transfer for dilute vapor species and small particles in air

    Science.gov (United States)

    Gokoglu, S. A.; Rosner, D. E.

    1984-01-01

    A simple engineering correlation scheme is developed to predict the variable property effects on dilute species laminar forced convection mass transfer applicable to all vapor molecules or Brownian diffusing small particle, covering the surface to mainstream temperature ratio of 0.25 T sub W/T sub e 4. The accuracy of the correlation is checked against rigorous numerical forced convection laminar boundary layer calculations of flat plate and stagnation point flows of air containing trace species of Na, NaCl, NaOH, Na2SO4, K, KCl, KOH, or K2SO4 vapor species or their clusters. For the cases reported here the correlation had an average absolute error of only 1 percent (maximum 13 percent) as compared to an average absolute error of 18 percent (maximum 54 percent) one would have made by using the constant-property results.

  7. Detection of significant cm to sub-mm band radio and gamma-ray correlated variability in Fermi bright blazars

    CERN Document Server

    Fuhrmann, L; Chiang, J; Angelakis, E; Zensus, J A; Nestoras, I; Krichbaum, T P; Ungerechts, H; Sievers, A; Pavlidou, V; Readhead, A C S; Max-Moerbeck, W; Pearson, T J

    2014-01-01

    The exact location of the gamma-ray emitting region in blazars is still controversial. In order to attack this problem we present first results of a cross-correlation analysis between radio (11 cm to 0.8 mm wavelength, F-GAMMA program) and gamma-ray (0.1-300 GeV) ~ 3.5 year light curves of 54 Fermi-bright blazars. We perform a source stacking analysis and estimate significances and chance correlations using mixed source correlations. Our results reveal: (i) the first highly significant multi-band radio and gamma-ray correlations (radio lagging gamma rays) when averaging over the whole sample, (ii) average time delays (source frame: 76+/-23 to 7+/-9 days), systematically decreasing from cm to mm/sub-mm bands with a frequency dependence tau_r,gamma (nu) ~ nu^-1, in good agreement with jet opacity dominated by synchrotron self-absorption, (iii) a bulk gamma-ray production region typically located within/upstream of the 3 mm core region (tau_3mm,gamma=12+/-8 days), (iv) mean distances between the region of gamma-...

  8. Modeling Population Spike Trains with Specified Time-Varying Spike Rates, Trial-to-Trial Variability, and Pairwise Signal and Noise Correlations.

    Science.gov (United States)

    Lyamzin, Dmitry R; Macke, Jakob H; Lesica, Nicholas A

    2010-01-01

    As multi-electrode and imaging technology begin to provide us with simultaneous recordings of large neuronal populations, new methods for modeling such data must also be developed. Here, we present a model for the type of data commonly recorded in early sensory pathways: responses to repeated trials of a sensory stimulus in which each neuron has it own time-varying spike rate (as described by its PSTH) and the dependencies between cells are characterized by both signal and noise correlations. This model is an extension of previous attempts to model population spike trains designed to control only the total correlation between cells. In our model, the response of each cell is represented as a binary vector given by the dichotomized sum of a deterministic "signal" that is repeated on each trial and a Gaussian random "noise" that is different on each trial. This model allows the simulation of population spike trains with PSTHs, trial-to-trial variability, and pairwise correlations that match those measured experimentally. Furthermore, the model also allows the noise correlations in the spike trains to be manipulated independently of the signal correlations and single-cell properties. To demonstrate the utility of the model, we use it to simulate and manipulate experimental responses from the mammalian auditory and visual systems. We also present a general form of the model in which both the signal and noise are Gaussian random processes, allowing the mean spike rate, trial-to-trial variability, and pairwise signal and noise correlations to be specified independently. Together, these methods for modeling spike trains comprise a potentially powerful set of tools for both theorists and experimentalists studying population responses in sensory systems.

  9. The rate of nonallelic homologous recombination in males is highly variable, correlated between monozygotic twins and independent of age.

    Directory of Open Access Journals (Sweden)

    Jacqueline A L MacArthur

    2014-03-01

    Full Text Available Nonallelic homologous recombination (NAHR between highly similar duplicated sequences generates chromosomal deletions, duplications and inversions, which can cause diverse genetic disorders. Little is known about interindividual variation in NAHR rates and the factors that influence this. We estimated the rate of deletion at the CMT1A-REP NAHR hotspot in sperm DNA from 34 male donors, including 16 monozygotic (MZ co-twins (8 twin pairs aged 24 to 67 years old. The average NAHR rate was 3.5 × 10(-5 with a seven-fold variation across individuals. Despite good statistical power to detect even a subtle correlation, we observed no relationship between age of unrelated individuals and the rate of NAHR in their sperm, likely reflecting the meiotic-specific origin of these events. We then estimated the heritability of deletion rate by calculating the intraclass correlation (ICC within MZ co-twins, revealing a significant correlation between MZ co-twins (ICC = 0.784, p = 0.0039, with MZ co-twins being significantly more correlated than unrelated pairs. We showed that this heritability cannot be explained by variation in PRDM9, a known regulator of NAHR, or variation within the NAHR hotspot itself. We also did not detect any correlation between Body Mass Index (BMI, smoking status or alcohol intake and rate of NAHR. Our results suggest that other, as yet unidentified, genetic or environmental factors play a significant role in the regulation of NAHR and are responsible for the extensive variation in the population for the probability of fathering a child with a genomic disorder resulting from a pathogenic deletion.

  10. [Lack of correlation between retinal variables before treatment and poor functional response after focal photocoagulation in diabetic macular oedema].

    Science.gov (United States)

    Ávila-Alcaraz, Yoloxochilth; Razo Blanco-Hernández, Dulce Milagros; García-Rubio, Yatzul Zuhaila; Lima-Gómez, Virgilio

    2016-01-01

    Although photocoagulation reduces the incidence of moderate visual loss in eyes with focal diabetic macular oedema, some eyes may lose some vision after treatment. The proportion of eyes with poor functional response after photocoagulation, and whether any retinal variable is associated with this, is unknown. To determine the proportion of eyes with diabetic macular oedema that have a poor functional response after focal photocoagulation, and their associated features. A non-experimental, longitudinal, comparative and retrospective study was conducted. The proportion and 95% confidence intervals (CI) of diabetics with macular oedema that had a poor functional response after focal photocoagulation (any visual loss after 6 weeks) were identified. The means of retinal variables before treatment were compared between eyes with and without a poor functional response using the Student t test for independent means. The study included 115 eyes of patients aged 59.3 (SD 9.24) years. Visual acuity was greater than or equal to 0.5 in 63 eyes (54.8%). A total of 33 eyes had a poor functional response after photocoagulation (28.7%, 95% CI: 13.3 to 44.1). The comparison between retinal variables and visual acuity before treatment did not show any differences between eyes with or without a poor functional response and eyes. Retinal thickening and visual acuity improved or did not change in 71.3% of eyes with diabetic macular oedema with a single photocoagulation procedure. Retinal variables that are usually evaluated were unable to identify the remaining 28.7%, which could lose vision after that treatment, and would require additional interventions. Copyright © 2015 Academia Mexicana de Cirugía A.C. Published by Masson Doyma México S.A. All rights reserved.

  11. How well can body size represent effects of the environment on demographic rates? Disentangling correlated explanatory variables.

    Science.gov (United States)

    Brooks, Mollie E; Mugabo, Marianne; Rodgers, Gwendolen M; Benton, Timothy G; Ozgul, Arpat

    2016-03-01

    Demographic rates are shaped by the interaction of past and current environments that individuals in a population experience. Past environments shape individual states via selection and plasticity, and fitness-related traits (e.g. individual size) are commonly used in demographic analyses to represent the effect of past environments on demographic rates. We quantified how well the size of individuals captures the effects of a population's past and current environments on demographic rates in a well-studied experimental system of soil mites. We decomposed these interrelated sources of variation with a novel method of multiple regression that is useful for understanding nonlinear relationships between responses and multicollinear explanatory variables. We graphically present the results using area-proportional Venn diagrams. Our novel method was developed by combining existing methods and expanding upon them. We showed that the strength of size as a proxy for the past environment varied widely among vital rates. For instance, in this organism with an income breeding life history, the environment had more effect on reproduction than individual size, but with substantial overlap indicating that size encompassed some of the effects of the past environment on fecundity. This demonstrates that the strength of size as a proxy for the past environment can vary widely among life-history processes within a species, and this variation should be taken into consideration in trait-based demographic or individual-based approaches that focus on phenotypic traits as state variables. Furthermore, the strength of a proxy will depend on what state variable(s) and what demographic rate is being examined; that is, different measures of body size (e.g. length, volume, mass, fat stores) will be better or worse proxies for various life-history processes.

  12. Induced genetic variability and correlation studies for yield and its component traits in Groundnut (Arachis hypogaea L.

    Directory of Open Access Journals (Sweden)

    Channayya P. Hiremath , H. L. Nadaf and Keerthi,C.M

    2011-03-01

    Full Text Available Groundnut is one of the principal economic oilseed crops of the world, which has been exposed extensively to mutagenictreatments for induction of genetic variability. In the present experiment, estimates of genetic variability, heritability and geneticadvance were assessed for 12 different quantitative traits in the mutants derived from two Spanish Bunch groundnut cultivars, viz.TPG-41 and GPBD-4 with chemical and physical mutagenic agents. Wide genetic variations were observed for most of thequantitative traits studied as evidenced by higher mean, range, PCV and GCV values. Further genetic improvement throughselection for yield improvement should rely on number of primary branches per plant, 100-kernel weight, SMK% and shellingper cent as these mutants recorded higher genetic variability, heritability and genetic advance for these quantitative traits. Podyield was positively and significantly associated with number of primary branches, pod weight per plant, 100-kernel weight,sound matured per cent kernel and oil yield. These results clearly indicate that idirect selection for yield in groundnut is possiblethrough simultaneous improvement of these yield components

  13. Dynamics of Polymeric Fluids: Part Ⅱ The Molecular Theory of Die Swell: Correlation of Ultimate Die Swelling Effect to the Molecular Parameters and the Operational Variables

    Institute of Scientific and Technical Information of China (English)

    Mingshi SONG; Qiang XU; Guixian HU; Sizhu WU

    2006-01-01

    A general expression for the correlation of the simple shear(tanφ)to the molecular parameters and the shear rate(γ)was deduced. It shows that the simple shear(tanφ)may be resolved into free recoil(recoverable strain)and viscous heating(unrecoverable strain). The magnitudes of the simple shears for recoil(tanφE)and(tanφv)for viscous heating not only depended on the molecular parameters and the operational variables,but also on the exponential fractions of the recoverable(1-(W)γ)and unrecoverable((W)γ)conformations for recoil and viscous heating. Therefore the magnitudes of the simple shears(tanφE)for recoil and(tanφv)for viscous heating are, respectively, expressed as the partition function to the(1-(W)γ)th power and the partition function to the(-(W)γ)th power. Thus correlations of the total recoil and the ultimately recoverable strains to the molecular parameters [n', a, η0, G0NN and(1--(W)γ)] and the operational variables(·γ, (L/D)and tr)were deduced respectively, which show that at very different shear rates(0≤·γ≤∞)the polymeric liquids may exhibit a very different viscoelastic behaviors. After introducing the uniform two-dimensional extension, the definition of swelling ratio and the ratio of L to D [De=(L/D)], two expressions for the ultimate die swelling effect and the ultimate extrudate swelling ratio BEVT5 to the molecular parameters [n', a, η0, G0N and(1--(W)·γ)] and the operational variables(·γ,(L/D)and tr)were obtained. The two correlation expressions were verified by the experimental data of high-density polyethylene (HDPE) which shows that the two correlation expressions can be used to predict the correlations of the ultimate extrudate swelling behaviors of polymeric liquids to the molecular parameters and the operational variables.

  14. Bioactive compounds and antioxidant activity exhibit high intraspecific variability in Pleurotus ostreatus mushrooms and correlate well with cultivation performance parameters.

    Science.gov (United States)

    Koutrotsios, Georgios; Kalogeropoulos, Nick; Stathopoulos, Pantelis; Kaliora, Andriana C; Zervakis, Georgios I

    2017-05-01

    Experimental data related with oyster mushroom production and nutritional properties usually derive from the examination of only one strain, and hence their representativeness/usefulness is questionable. This work aims at assessing intraspecific variability in Pleurotus ostreatus by studying 16 strains, under the same conditions, in respect to essential cultivation and mushroom quality aspects, and by defining the impact of intrinsic/genetic factors on such parameters. Hence, mushroom yield, earliness, crop length, biological efficiency, productivity, and their content in selected macro and microconstituents (e.g. fatty acids, sterols, individual phenolic compounds, terpenic acids, glucans) as well as their antioxidant properties (i.e., antiradical activity, ferric reducing potential, inhibition of serum oxidation) were assayed. The effect of intrinsic/genetic factors was evident, especially as regards earliness, yield of each production flush and mushroom weight, whereas biological efficiency was not particularly influenced by the cultivated strain. Moreover, phenolics, ergosterol and antiradical activity demonstrated significant variability among strains in contrast to what was observed for fatty acids, β-glucans and ferric reducing potential. The observed heterogeneity reveals the limitations of using a low number of strains for evaluating mushroom production and/or their content in bioactive compounds, and as evidenced, it is valuable for breeding and commercial purposes.

  15. Phenotype variability and early onset ataxia symptoms in spinocerebellar ataxia type 7: comparison and correlation with other spinocerebellar ataxias

    Directory of Open Access Journals (Sweden)

    Marcus Vinicius Cristino de Albuquerque

    2015-01-01

    Full Text Available The spinocerebellar ataxias (SCA are a group of neurodegenerative disorders characterized by heterogeneous clinical presentation. Spinocerebellar ataxia type 7 (SCA7 is caused by an abnormal CAG repeat expansion and includes cerebellar signs associated with visual loss and ophthalmoplegia. Marked anticipation and dynamic mutation is observed in SCA7. Moreover, phenotype variability and very early onset of symptoms may occur. In this article, a large series of Brazilian patients with different SCA subtypes was evaluated, and we compared the age of onset of SCA7 with other SCA. From the 26 patients with SCA7, 4 manifested their symptoms before 10-year-old. Also, occasionally the parents may have the onset of symptoms after their children. In conclusion, our study highlights the genetic anticipation phenomenon that occurs in SCA7 families. Patients with very early onset ataxia in the context of a remarkable family history, must be considered and tested for SCA7.

  16. Phenotype variability and early onset ataxia symptoms in spinocerebellar ataxia type 7: comparison and correlation with other spinocerebellar ataxias.

    Science.gov (United States)

    Albuquerque, Marcus Vinicius Cristino de; Pedroso, José Luiz; Braga Neto, Pedro; Barsottini, Orlando Graziani Povoas

    2015-01-01

    The spinocerebellar ataxias (SCA) are a group of neurodegenerative disorders characterized by heterogeneous clinical presentation. Spinocerebellar ataxia type 7 (SCA7) is caused by an abnormal CAG repeat expansion and includes cerebellar signs associated with visual loss and ophthalmoplegia. Marked anticipation and dynamic mutation is observed in SCA7. Moreover, phenotype variability and very early onset of symptoms may occur. In this article, a large series of Brazilian patients with different SCA subtypes was evaluated, and we compared the age of onset of SCA7 with other SCA. From the 26 patients with SCA7, 4 manifested their symptoms before 10-year-old. Also, occasionally the parents may have the onset of symptoms after their children. In conclusion, our study highlights the genetic anticipation phenomenon that occurs in SCA7 families. Patients with very early onset ataxia in the context of a remarkable family history, must be considered and tested for SCA7.

  17. Differences in protein quality control correlate with phenotype variability in 2 mouse models of familial amyotrophic lateral sclerosis.

    Science.gov (United States)

    Marino, Marianna; Papa, Simonetta; Crippa, Valeria; Nardo, Giovanni; Peviani, Marco; Cheroni, Cristina; Trolese, Maria Chiara; Lauranzano, Eliana; Bonetto, Valentina; Poletti, Angelo; DeBiasi, Silvia; Ferraiuolo, Laura; Shaw, Pamela J; Bendotti, Caterina

    2015-01-01

    Amyotrophic lateral sclerosis (ALS) is a disease of variable severity in terms of speed of progression of the disease course. We found a similar variability in disease onset and progression of 2 familial ALS mouse strains, despite the fact that they carry the same transgene copy number and express the same amount of mutant SOD1G93A messenger RNA and protein in the central nervous system. Comparative analysis of 2 SOD1G93A mouse strains highlights differences associated with the disease severity that are unrelated to the degree of motor neuron loss but that appear to promote early dysfunction of these cells linked to protein aggregation. Features of fast progressing phenotype are (1) abundant protein aggregates containing mutant SOD1 and multiple chaperones; (2) low basal expression of the chaperone alpha-B-crystallin (CRYAB) and β5 subunits of proteasome; and (3) downregulation of proteasome subunit expression at disease onset. In contrast, high levels of functional chaperones such as cyclophillin-A and CRYAB, combined with delayed alteration of expression of proteasome subunits and the sequestration of TDP43 into aggregates, are features associated with a more slowly progressing pathology. These data support the hypothesis that impairment of protein homeostasis caused by low-soluble chaperone levels, together with malfunction of the proteasome degradation machinery, contributes to accelerate motor neuron dysfunction and progression of disease symptoms. Therefore, modulating the activity of these systems could represent a rational therapeutic strategy for slowing down disease progression in SOD1-related ALS. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Comparison between the Suomi-NPP Day-Night Band and DMSP-OLS for Correlating Socio-Economic Variables at the Provincial Level in China

    Directory of Open Access Journals (Sweden)

    Xin Jing

    2015-12-01

    Full Text Available Nighttime light imagery offers a unique view of the Earth’s surface. In the past, the nighttime light data collected by the DMSP-OLS sensors have been used as an efficient means to correlate regional and global socio-economic activities. With the launch of the Suomi National Polar-orbiting Partnership (Suomi-NPP satellite in 2011, the day-night band (DNB of the Visible Infrared Imaging Radiometer Suite (VIIRS onboard represents a major advancement in nighttime imaging capabilities, because it surpasses its predecessor DMSP-OLS in radiometric accuracy, spatial resolution and geometric quality. In this paper, four variables (total night light, light area, average night light and log average night light are extracted from nighttime radiance data observed by the VIIRS-DNB composite in 2013 and nighttime digital number (DN data from the DMSP-OLS stable dataset in 2012, respectively, and correlated with 12 socio-economic parameters at the provincial level in mainland China during the corresponding period. Background noise of DNB composite data is removed using either a masking method or an optimal threshold method. In general, the correlation of these socio-economic data with the total night light and light area of VIIRS-DNB composite data is better than with the DMSP-OLS stable data. The correlations between total night light of denoised DNB composite data and built-up area, gross regional product (GRP and power consumption are higher than 0.9 and so are the correlations between the light area of denoised DNB composite data and city and town population, built-up area, GRP, power consumption and waste water discharge. However, the correlations of socio-economic data with the average night light and log average night light of VIIRS-DNB composite data are not as good as with the DMSP-OLS stable data. To quantitatively analyze the reasons for the correlation difference, a cubic regression method is developed to correct the saturation effect of the DMSP

  19. Application of Input-output Theory in the Analysis of Economic Structure--Taking the Industrial Correlation Analysis of Shaanxi Province as Example%投入产出原理在经济结构分析中的应用--以陕西省各产业关联分析为例

    Institute of Scientific and Technical Information of China (English)

    潘媛

    2014-01-01

    In this thesis,the author built Shaanxi Provincial Economic Leap’s Input-output Table,and constructed its mathematical model. Then,applying the theory of input-output,the author analyzed the correlation analysis of the industry. According to the correlation analysis of the industry,we can conclude the status and the development order of all the ten clusters .%建立了《陕西省十大产业集群的投入产出表》及其数学模型,并运用投入产出原理,着重对陕西省各产业集群相互之间的产业关联关系进行分析,从而得出各产业集群的地位和发展顺序。

  20. Mutation screening of familial Mediterranean fever in the Azeri Turkish population: Genotype-phenotype correlation and the clinical profile variability

    Directory of Open Access Journals (Sweden)

    Gharesouran Jalal

    2014-01-01

    Full Text Available Familial Mediterranean fever is known as a most frequent hereditary autoin-Xammatory among the autoinflammatory syndromes characterized by fever, arthritis and serosal inflammation. Clinically, the foremost severe symptom of the disease is amyloidosis, which may cause to renal failure. MEFV renal failure consists of ten exons and conservative mutations clustered in exon ten (M694V, V726A, M680I, M694I and exon two (E148Q are considered more common mutations within this coding region and that they are detected with a distinct frequency changes in line with ethnicity. The aim of this study was to research the spectrum of mutations in Azeri Turkish population. We evaluated the molecular test results of 82 patients and their parents from eighty families identified as having FMF clinical symptoms referred to Molecular Genetics Laboratory of the Department of Medical Genetics. Patients were referred by their physicians for MEFV mutation detection. The most frequent mutations were M694V respectively followed by M680I (G/C, V726A, M694I and E148Q mutations. A phenotypic variability was also ascertained between patients with different mutations and it must be considered within the daily management of FMF patients.

  1. Heat rate variability and dyssomnia and their correlations to neurological defects in cerebral infarction patients complicated by insomnia A concurrent non-randomized case-control study

    Institute of Scientific and Technical Information of China (English)

    Jianping Chu; Xueli Shen; Jun Fan; Changhai Chen; Shuyang Lin

    2008-01-01

    BACKGROUND: Heart rate variability refers to the beat-to-beat alteration in heart rate. It is usually a slight periodic variation of R-R intervals. Much information of autonomic nerve system balance can be obtained by measuring the heart rate variability of patients. It remains to be shown whether heart rate variability can be used as an index for determining the severity of insomnia and cerebral infarction. OBJECTIVE: This study aimed to analyze the correlation for each frequency spectrum parameter of heart rate variability with an insomnia index, as well as the degree of neurological defects in patients with simple cerebral infarction and cerebral infarction complicated by insomnia. The goal was to verify the feasibility of frequency spectrum parameters for heart rate variability as a marker for insomnia and cerebral infarction. DESIGN: A case-control observation. SETTING: Department of Neurology, First Hospital Affiliated to China Medical University. PARTICIPANTS: Sixty inpatients, and/or outpatients, with cerebral infarction were admitted to the 202 Hospital of Chinese PLA between December 2005 and October 2006, confirmed by CT, and recruited to the study. According to the insomnia condition (insomnia is defined by a Pittsburgh Sleep Quality Index score > 7), the patients were assigned to a simple cerebral infarction group and a cerebral infarction complicated by insomnia group, with 30 subjects in each group. Thirty additional subjects, who concurrently received ex-aminations and were confirmed to not suffer from cerebral infarction and insomnia, were recruited into the control group. Written informed consent was obtained from each subject for laboratory specimens. The pro-tocol was approved by the Hospital's Ethics Committee. METHODS: Following admission, each subject's neurological impairment was assessed with the National Institutes of Health Stroke Scale and Pittsburgh Sleep Quality Index. Heart rate variability of each subject was measured with an

  2. Analysis of Negative Correlation Learning

    Institute of Scientific and Technical Information of China (English)

    Liu Yong; Zou Xiu-fen

    2003-01-01

    This paper describes negative correlation learning for designing neural network ensembles. Negative correlation learning has been firstly analysed in terms of minimising mutual information on a regression task. By ninimising the mutual information between variables extracted by two neural networks, they are forced to convey different information about some features of their input. Based on the decision boundaries and correct response sets, negative correlation learning has been further studied on two pattern classification problems. The purpose of examining the decision boundaries and the correct response sets is not only to illustrate the learning behavior of negative correlation learning, but also to cast light on how to design more effective neural network ensembles. The experimental results showed the decision boundary of the trained neural network ensemble by negative correlation learning is almost as good as the optimum decision boundary.

  3. Correlation and Synchrony Transfer in Integrate-and-Fire Neurons: Basic Properties and Consequences for Coding

    Science.gov (United States)

    Shea-Brown, Eric; Josić, Krešimir; de La Rocha, Jaime; Doiron, Brent

    2008-03-01

    We study how pairs of neurons transfer correlated input currents into correlated spikes. Over rapid time scales, correlation transfer increases with both spike time variability and rate; the dependence on variability disappears at large time scales. This persists for a nonlinear membrane model and for heterogeneous cell pairs, but strong nonmonotonicities follow from refractory effects. We present consequences for population coding and for the encoding of time-varying stimuli.

  4. Optimal time scales of input fluctuations for spiking coherence and reliability in stochastic Hodgkin-Huxley neurons

    Science.gov (United States)

    Guo, Xinmeng; Wang, Jiang; Liu, Jing; Yu, Haitao; Galán, Roberto F.; Cao, Yibin; Deng, Bin

    2017-02-01

    Channel noise, which is generated by the random transitions of ion channels between open and closed states, is distinguished from external sources of physiological variability such as spontaneous synaptic release and stimulus fluctuations. This inherent stochasticity in ion-channel current can lead to variability of the timing of spikes occurring both spontaneously and in response to stimuli. In this paper, we investigate how intrinsic channel noise affects the response of stochastic Hodgkin-Huxley (HH) neuron to external fluctuating inputs with different amplitudes and correlation time. It is found that there is an optimal correlation time of input fluctuations for the maximal spiking coherence, where the input current has a fluctuating rate approximately matching the inherent oscillation of stochastic HH model and plays a dominating role in the timing of spike firing. We also show that the reliability of spike timing in the model is very sensitive to the properties of the current input. An optimal time scale of input fluctuations exists to induce the most reliable firing. The channel-noise-induced unreliability can be mostly overridden by injecting a fluctuating current with an appropriate correlation time. The spiking coherence and reliability can also be regulated by the size of channel stochasticity. As the membrane area (or total channel number) of the neuron increases, the spiking coherence decreases but the spiking reliability increases.

  5. Long-term variability of the optical spectra of NGC 4151: I. Light curves and flux correlations

    CERN Document Server

    Shapovalova, A I; Collin, S; Burenkov, A N; Chavushyan, V H; Bochkarev, N G; Benitz, E; Dultzin-Hacyan, D; Kovacevic, A; Borisov, N; Carrasco, L; Leon-Tavares, J; Mercado, A; Valdés, J R; Vlasuyk, V V; Zhdanova, V E

    2008-01-01

    Results of a long-term spectral monitoring of the active galactic nucleus of NGC 4151 are presented (11 years, from 1996 to 2006). High quality spectra (S/N>50 in the continuum near Halpha and Hbeta) were obtained in the spectral range ~4000 to 7500 \\AA, with a resolution between 5 and 15 A, using the 6-m and the 1-m SAO's telescopes (Russia), the GHAO's 2.1-m telescope (Cananea, Mexico), and the OAN-SPM's 2.1-m telescope (San-Pedro, Mexico). The observed fluxes of the Halpha, Hbeta, Hgamma and HeII emission lines and of the continuum at the observed wavelength 5117 A, were corrected for the position angle, the seeing and the aperture effects. We found that the continuum and line fluxes varied strongly (up to a factor 6) during the monitoring period. The emission was maximum in 1996-1998, and there were two minima, in 2001 and in 2005. The Halpha, Hgamma and He II fluxes were well correlated with the Hbeta flux. We considered three characteristic periods during which the Hbeta and Halpha profiles were similar...

  6. Variable Spin-Down in the Soft Gamma Repeater SGR 1900+14 and Correlations with Burst Activity

    Science.gov (United States)

    Woods, Peter M.; Kouveliotou, Chryssa; VanParadijs, Jan; Finger, Mark H.; Thompson, Christopher; Duncan, Robert C.; Hurley, Kevin; Strohmayer, Tod; Swank, Jean; Murakami, Toshio

    1999-01-01

    We have analyzed Rossi X-ray Timing Explorer Proportional Counter Array observations of the pulsed emission from SGR 1900+ 14 during 1996 September, 1998 June-October, and early 1999. Using these measurements and results reported elsewhere, we construct a period history of this source for 2.5 yr. We find significant deviations from a steady spin-down trend during quiescence and the burst active interval. Burst and Transient Source Experiment observations of the burst emission are presented and correlations between the burst activity and spin-down rate of SGR 1900+14 are discussed. We find an 80 day interval during the summer of 1998 when the average spin-down rate is larger than the rate elsewhere by a factor approximately 2.3. This enhanced spin-down may be the result of a discontinuous spin-down event or "braking glitch" at the time of the giant flare on 1998 August 27. Furthermore, we find a large discrepancy between the pulsar period and average spin-down rate in X-rays as compared to radio observations for 1998 December and 1999 January.

  7. Intracellular CD3+ T Lymphocyte Teriflunomide Concentration Is Poorly Correlated with and Has Greater Variability Than Unbound Plasma Teriflunomide Concentration.

    Science.gov (United States)

    Hopkins, Ashley M; Moghaddami, Mahin; Foster, David J R; Proudman, Susanna M; Upton, Richard N; Wiese, Michael D

    2017-01-01

    Leflunomide's active metabolite teriflunomide inhibits dihydro-oroate dehydrogenase, an enzyme essential to proliferation of T lymphocytes. As teriflunomide must reach the target site to have this effect, this study assessed the distribution of teriflunomide into T lymphocytes, as intracellular concentrations may be a superior response biomarker to plasma concentrations. CD3 MicroBeads (Miltenyi Biotec, Bergisch Gladbach, Germany) were used to extract CD3(+) T cells from the peripheral blood of patients with rheumatoid arthritis who were taking a stable dose of leflunomide. Unbound plasma and intra-CD3(+) T cell teriflunomide concentrations were quantified using liquid chromatography-mass spectrometry. Concentration (log transformed) and partition differences were assessed through paired Student t tests. Sixteen patients provided plasma steady-state teriflunomide samples, and eight provided a sample 6-12 weeks later. At time-point one, the geometric mean teriflunomide concentration (range) in CD3(+) T cells was 18.12 μg/L (6.15-42.26 μg/L) compared with 69.75 μg/L (32.89-263.1 μg/L) unbound in plasma (P < 0.001). The mean partition coefficient (range) for unbound plasma teriflunomide into CD3(+) T cells was 0.295 (0.092-0.632), which was significantly different from unity (P < 0.001). The median (range) change in teriflunomide concentration between the two time points was 14% (-10% to 40%) in unbound plasma and -29% (-69 to 138%) for CD3(+) T cells. Because teriflunomide concentrations in CD3(+) T cells were lower and displayed a higher intraindividual variability than the unbound plasma concentrations, its applicability as a therapeutic drug-monitoring marker may be limited. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  8. Variable aromatase inhibitor plasma concentrations do not correlate with circulating estrogen concentrations in post-menopausal breast cancer patients.

    Science.gov (United States)

    Hertz, Daniel L; Speth, Kelly A; Kidwell, Kelley M; Gersch, Christina L; Desta, Zeruesenay; Storniolo, Anna Maria; Stearns, Vered; Skaar, Todd C; Hayes, Daniel F; Henry, N Lynn; Rae, James M

    2017-06-22

    The aromatase inhibitors (AI) exemestane (EXE), letrozole (LET), and anastrozole suppress estrogen biosynthesis, and are effective treatments for estrogen receptor (ER)-positive breast cancer. Prior work suggests that anastrozole blood concentrations are associated with the magnitude of estrogen suppression. The objective of this study was to determine whether the magnitude of estrogen suppression, as determined by plasma estradiol (E2) concentrations, in EXE or LET treated patients is associated with plasma AI concentrations. Five hundred post-menopausal women with ER-positive breast cancer were enrolled in the prospective Exemestane and Letrozole Pharmacogenetic (ELPh) Study conducted by the COnsortium on BReast cancer phArmacogomics (COBRA) and randomly assigned to either drug. Estrogen concentrations were measured at baseline and after 3 months of AI treatment and drug concentrations were measured after 1 or 3 months. EXE or LET concentrations were compared with 3-month E2 concentration or the change from baseline to 3 months using several complementary statistical procedures. Four-hundred patients with on-treatment E2 and AI concentrations were evaluable (EXE n = 200, LET n = 200). Thirty (7.6%) patients (EXE n = 13, LET n = 17) had 3-month E2 concentrations above the lower limit of quantification (LLOQ) (median: 4.75; range: 1.42-63.8 pg/mL). EXE and LET concentrations were not associated with on-treatment E2 concentrations or changes in E2 concentrations from baseline (all p > 0.05). Steady-state plasma AI concentrations do not explain variability in E2 suppression in post-menopausal women receiving EXE or LET therapy, in contrast with prior evidence in anastrozole treated patients.

  9. Formulation of a correlated variables methodology for assessment of continuous gas resources with an application to the Woodford play, Arkoma Basin, eastern Oklahoma

    Science.gov (United States)

    Olea, R.A.; Houseknecht, D.W.; Garrity, C.P.; Cook, T.A.

    2011-01-01

    Shale gas is a form of continuous unconventional hydrocarbon accumulation whose resource estimation is unfeasible through the inference of pore volume. Under these circumstances, the usual approach is to base the assessment on well productivity through estimated ultimate recovery (EUR). Unconventional resource assessments that consider uncertainty are typically done by applying analytical procedures based on classical statistics theory that ignores geographical location, does not take into account spatial correlation, and assumes independence of EUR from other variables that may enter into the modeling. We formulate a new, more comprehensive approach based on sequential simulation to test methodologies known to be capable of more fully utilizing the data and overcoming unrealistic simplifications. Theoretical requirements demand modeling of EUR as areal density instead of well EUR. The new experimental methodology is illustrated by evaluating a gas play in the Woodford Shale in the Arkoma Basin of Oklahoma. Differently from previous assessments, we used net thickness and vitrinite reflectance as secondary variables correlated to cell EUR. In addition to the traditional probability distribution for undiscovered resources, the new methodology provides maps of EUR density and maps with probabilities to reach any given cell EUR, which are useful to visualize geographical variations in prospectivity.

  10. Input or intimacy

    Directory of Open Access Journals (Sweden)

    Judit Navracsics

    2014-01-01

    Full Text Available According to the critical period hypothesis, the earlier the acquisition of a second language starts, the better. Owing to the plasticity of the brain, up until a certain age a second language can be acquired successfully according to this view. Early second language learners are commonly said to have an advantage over later ones especially in phonetic/phonological acquisition. Native-like pronunciation is said to be most likely to be achieved by young learners. However, there is evidence of accentfree speech in second languages learnt after puberty as well. Occasionally, on the other hand, a nonnative accent may appear even in early second (or third language acquisition. Cross-linguistic influences are natural in multilingual development, and we would expect the dominant language to have an impact on the weaker one(s. The dominant language is usually the one that provides the largest amount of input for the child. But is it always the amount that counts? Perhaps sometimes other factors, such as emotions, ome into play? In this paper, data obtained from an EnglishPersian-Hungarian trilingual pair of siblings (under age 4 and 3 respectively is analyzed, with a special focus on cross-linguistic influences at the phonetic/phonological levels. It will be shown that beyond the amount of input there are more important factors that trigger interference in multilingual development.

  11. Variability study with CD-SEM metrology for STT-MRAM: correlation analysis between physical dimensions and electrical property of the memory element

    Science.gov (United States)

    Ohashi, Takeyoshi; Yamaguchi, Atsuko; Hasumi, Kazuhisa; Inoue, Osamu; Ikota, Masami; Lorusso, Gian; Donadio, Gabriele Luca; Yasin, Farrukh; Rao, Siddharth; Kar, Gouri Sankar

    2017-03-01

    A methodology to evaluate the memory cell property of STT-MRAM (Spin Transfer Torque-Magnetic Random Access Memory) with a CD-SEM (Critical Dimension-Scanning Electron Microscope) was proposed. STTMRAM is one of the promising candidates among various emerging memories, owing to its low power consumption, low latency, and excellent endurance. Meanwhile, the major issues of STT-MRAM are its small resistance window and the etching-induced damage during memory pillar formation process. The resistance variability and the damage region should be minimized to achieve the reliable operation and the size scaling. The correlation analysis between the resistance and the physical dimension was performed. It provided quantitative information required for process development and control, such as the size-independent resistance variability, the width of the damaged region, and the origin of the short failures. They are essential for the investigation of the causes for the cell-to-cell resistance variability as well as for the quantification of the damage during etching process.

  12. Effect of trial-to-trial variability on optimal event-related fMRI design: Implications for Beta-series correlation and multi-voxel pattern analysis.

    Science.gov (United States)

    Abdulrahman, Hunar; Henson, Richard N

    2016-01-15

    Functional magnetic resonance imaging (fMRI) studies typically employ rapid, event-related designs for behavioral reasons and for reasons associated with statistical efficiency. Efficiency is calculated from the precision of the parameters (Betas) estimated from a General Linear Model (GLM) in which trial onsets are convolved with a Hemodynamic Response Function (HRF). However, previous calculations of efficiency have ignored likely variability in the neural response from trial to trial, for example due to attentional fluctuations, or different stimuli across trials. Here we compare three GLMs in their efficiency for estimating average and individual Betas across trials as a function of trial variability, scan noise and Stimulus Onset Asynchrony (SOA): "Least Squares All" (LSA), "Least Squares Separate" (LSS) and "Least Squares Unitary" (LSU). Estimation of responses to individual trials in particular is important for both functional connectivity using "Beta-series correlation" and "multi-voxel pattern analysis" (MVPA). Our simulations show that the ratio of trial-to-trial variability to scan noise impacts both the optimal SOA and optimal GLM, especially for short SOAsdesign of experiments using Beta-series regression and MVPA, but also statistical parametric mapping studies that seek only efficient estimation of the mean response across trials.

  13. Old processes, new perspectives: Familiarity is correlated with (not independent of) recollection and is more (not equally) variable for targets than for lures.

    Science.gov (United States)

    Moran, Rani; Goshen-Gottstein, Yonatan

    2015-06-01

    According to dual-process models of memory, recognition is subserved by two processes: recollection and familiarity. Many variants of these models assume that recollection and familiarity make stochastically independent contributions to performance in recognition tasks and that the variance of the familiarity signal is equal for targets and for lures. Here, we challenge these 'common-currency' assumptions. Using a model-comparison approach, featuring the Continuous Dual Process (CDP; Wixted & Mickes, 2010) model as the protagonist, we show that when these assumptions are relaxed, the model's fits to individual participants' data improve. Furthermore, our analyses reveal that across items, recollection and familiarity show a positive correlation. Interestingly, this across-items correlation was dissociated from an across-participants correlation between the sensitivities of these processes. We also find that the familiarity signal is significantly more variable for targets than for lures. One striking theoretical implication of these findings is that familiarity-rather than recollection, as most models assume-may be the main contributor responsible for one of the most influential findings of recognition memory, that of subunit zROC slopes. Additionally, we show that erroneously adopting the common-currency assumptions, introduces severe biases to estimates of recollection and familiarity.

  14. Access to Research Inputs

    DEFF Research Database (Denmark)

    Czarnitzki, Dirk; Grimpe, Christoph; Pellens, Maikel

    The viability of modern open science norms and practices depend on public disclosure of new knowledge, methods, and materials. However, increasing industry funding of research can restrict the dissemination of results and materials. We show, through a survey sample of 837 German scientists in life...... sciences, natural sciences, engineering, and social sciences, that scientists who receive industry funding are twice as likely to deny requests for research inputs as those who do not. Receiving external funding in general does not affect denying others access. Scientists who receive external funding...... of any kind are, however, 50% more likely to be denied access to research materials by others, but this is not affected by being funded specifically by industry....

  15. Access to Research Inputs

    DEFF Research Database (Denmark)

    Czarnitzki, Dirk; Grimpe, Christoph; Pellens, Maikel

    2015-01-01

    The viability of modern open science norms and practices depends on public disclosure of new knowledge, methods, and materials. However, increasing industry funding of research can restrict the dissemination of results and materials. We show, through a survey sample of 837 German scientists in life...... sciences, natural sciences, engineering, and social sciences, that scientists who receive industry funding are twice as likely to deny requests for research inputs as those who do not. Receiving external funding in general does not affect denying others access. Scientists who receive external funding...... of any kind are, however, 50 % more likely to be denied access to research materials by others, but this is not affected by being funded specifically by industry...

  16. Seasonal and interannual variability of sedimentation and organic matter distribution in the Buor Khaya Gulf – the primary recipient of input from Lena River and coastal erosion in the SE Laptev Sea

    Directory of Open Access Journals (Sweden)

    A. N. Charkin

    2011-02-01

    Full Text Available Climate warming is amplified in the land-sea system of the East Siberian Arctic, which also holds large pools of vulnerable carbon in permafrost. This coastal area is strongly influenced by sediment and carbon transport from both its large rivers and extensive erosion of Pleistocene permafrost along its coastline. This study is investigating the coastal fate of the sediment and organic carbon delivered to the Buor-Khaya Gulf, which is the first recipient of the 16 overwhelming fluvial discharge from the Lena River and is additionally receiving large input from extensive erosion of the coastal ice-complex (permafrost a.k.a. Yedoma; loess soil with high organic carbon content. Both water column suspended particulate matter (SPM and surface sediments were sampled at about 250 oceanographic stations in the Gulf in this multiyear effort, including one winter campaign, and analyzed for the distribution and sorting of sediment size, organic carbon content, and stable carbon isotope signals. The composition of the surface sediment suggests an overwhelmingly terrestrial contribution from both river and coastal erosion.

    Based on data collected during several years in the period 2000–2008, two different sedimentation regimes were revealed for the Buor-Khaya Gulf, the relative importance of each at a given time depend on hydrometeorological conditions, the Lena River water discharge and sea-ice regime: Type 1 erosion-accumulation and Type 2 accumulation.

    The Type 1 erosion-accumulation sedimentation regime is typical (2000–2006 for the ice-free period of the year (here considered in detail for August 2005. Under such conditions terrigenous sources of suspended particulate matter (SPM and particulate organic carbon (POC stem predominantly from river discharge, thermal erosion of coastal ice-complex and remobilized bottom sediments. The Type 2 accumulation sedimentation regime develops under ice

  17. Correlator technology

    NARCIS (Netherlands)

    Schooneveld, C. van

    1968-01-01

    The paper reviews a number of designs of cross-correlation receivers for the detection of active underwater transmissions. Particular attention is given to the various structures of phase insensitive receivers, and to the problems concerned with clipping of the input signal and the reference functio

  18. Correlation analysis of Normalized Different Vegetation Index (NDVI)difference series and climate variables in the Xilingole steppe,China from 1983 to 1999

    Institute of Scientific and Technical Information of China (English)

    GU Zhihui; CHEN Jin; SHI Peijun; XU Ming

    2007-01-01

    There is a crucial need in the study of global change to understand how terrestrial ecosystems respond to the climate system.It has been demonstrated by many researches that Normalized Different Vegetation Index (NDVI)time series from remotely sensed data,which provide effective information of vegetation conditions on a large scale with highly temporal resolution,have a good relation with meteorological factors.However,few of these studies have taken the cumulative property of NDVI time series into account.In this study,NDVI difference series were proposed to replace the original NDVI time series with NDVI difference series to reappraise the relationship between NDVI and meteorological factors.As a proxy of the vegetation growing process,NDVI difference represents net primary productivity of vegetation at a certain time interval under an environment controlled by certain climatic conditions and other factors.This data replacement is helpful to eliminate the cumulative effect that exist in original NDVI time series,and thus is more appropriate to understand how climate system affects vegetation growth in a short time scale.By using the correlation analysis method,we studied the relationship between NOAA/AVHRR ten-day NDVI difference series and corresponding meteorological data from 1983 to 1999 from 11 meteorological stations located in the Xilingole steppe in Inner Mongolia.The results show that:(1)meteorological factors are found to be more significantly correlation with NDVI difference at the biomass-rising phase than that at the falling phase;(2)the relationship between NDVI difference and climate variables varies with vegetation types and vegetation communities.In a typical steppe dominated by Leymus chinensis,temperature has higher correlation with NDVI difference than precipitation does,and in a typical steppe dominated by Stipa krylovii,the correlation between temperature and NDVI difference is lower than that between precipitation and NDVI difference.In a

  19. A Stochastic Collocation Method for Elliptic Partial Differential Equations with Random Input Data

    KAUST Repository

    Babuška, Ivo

    2010-01-01

    This work proposes and analyzes a stochastic collocation method for solving elliptic partial differential equations with random coefficients and forcing terms. These input data are assumed to depend on a finite number of random variables. The method consists of a Galerkin approximation in space and a collocation in the zeros of suitable tensor product orthogonal polynomials (Gauss points) in the probability space, and naturally leads to the solution of uncoupled deterministic problems as in the Monte Carlo approach. It treats easily a wide range of situations, such as input data that depend nonlinearly on the random variables, diffusivity coefficients with unbounded second moments, and random variables that are correlated or even unbounded. We provide a rigorous convergence analysis and demonstrate exponential convergence of the “probability error” with respect to the number of Gauss points in each direction of the probability space, under some regularity assumptions on the random input data. Numerical examples show the effectiveness of the method. Finally, we include a section with developments posterior to the original publication of this work. There we review sparse grid stochastic collocation methods, which are effective collocation strategies for problems that depend on a moderately large number of random variables.

  20. Correlated optical/X-ray variability in the high-mass X-ray binary SAX J2103.5+4545

    CERN Document Server

    Reig, P; Zezas, A; Blay, P

    2009-01-01

    SAX J2103.5+4545 is the Be/X-ray binary with the shortest orbital period. It shows extended bright and faint X-ray states that last for a few hundred days. The main objective of this work is to investigate the relationship between the X-ray and optical variability and to characterise the spectral and timing properties of the bright and faint states. We have found a correlation between the spectral and temporal parameters that fit the energy and power spectra. Softer energy spectra correspond to softer power spectra. That is to say, when the energy spectrum is soft the power at high frequencies is suppressed. We also present the results of our monitoring of the Halpha line of the optical counterpart since its discovery in 2003. There is a correlation between the strength and shape of the Halpha line, originated in the circumstellar envelope of the massive companion and the X-ray emission from the vicinity of the neutron star. Halpha emission, indicative of an equatorial disc around the B-type star, is detected...

  1. Seasonality of reproduction in male spotted murrel Channa punctatus: correlation of environmental variables and plasma sex steroids with histological changes in testis.

    Science.gov (United States)

    Basak, Reetuparna; Roy, Alivia; Rai, Umesh

    2016-10-01

    The present study was undertaken to develop a comprehensive understanding of how environmental cues and sex steroids relate with cyclic changes in spermatogenesis in freshwater spotted snakehead Channa punctatus that is nutritious and economically important. The seasonal histological changes in testis and annual profile of gonadosomatic index (GSI) of C. punctatus delineated the testicular cycle into four phases: regressed (December-March), preparatory (April-June), spawning (July and August) and postspawning (September-November). Among environmental variables, correlation and regression analyses exhibited an important relationship between photoperiod and testicular weight while role of rainfall was seen confined to spawning. The seasonal profile of plasma sex steroids when correlated with cyclic changes in spermatogenesis in spotted snakehead, testosterone (T) seems to be involved in controlling the major events of spermatogenesis from renewal of stem cells to spawning of spermatozoa. Another important androgen prevalent in teleosts, 11-ketotestosterone (11-KT), was high during preparatory phase, suggesting that 11-KT in addition to T plays an important role in progression of spermatogenesis and spermiation in C. punctatus. However, 11-KT was not seen to be associated with milt production and release of spermatozoa during spawning. Plasma profile of estradiol-17β (E2) during different reproductive phases revealed the involvement of E2 in repopulation of stem cells during postspawning phase and in maintaining quiescence of testis during regressed phase.

  2. The Kepler Input Catalog

    Science.gov (United States)

    Latham, D. W.; Brown, T. M.; Monet, D. G.; Everett, M.; Esquerdo, G. A.; Hergenrother, C. W.

    2005-12-01

    The Kepler mission will monitor 170,000 planet-search targets during the first year, and 100,000 after that. The Kepler Input Catalog (KIC) will be used to select optimum targets for the search for habitable earth-like transiting planets. The KIC will include all known catalogued stars in an area of about 177 square degrees centered at RA 19:22:40 and Dec +44:30 (l=76.3 and b=+13.5). 2MASS photometry will be supplemented with new ground-based photometry obtained in the SDSS g, r, i, and z bands plus a custom filter centered on the Mg b lines, using KeplerCam on the 48-inch telescope at the Whipple Observatory on Mount Hopkins, Arizona. The photometry will be used to estimate stellar characteristics for all stars brighter than K 14.5 mag. The KIC will include effective temperature, surface gravity, metallicity, reddening, distance, and radius estimates for these stars. The CCD images are pipeline processed to produce instrumental magnitudes at PSI. The photometry is then archived and transformed to the SDSS system at HAO, where the astrophysical analysis of the stellar characteristics is carried out. The results are then merged with catalogued data at the USNOFS to produce the KIC. High dispersion spectroscopy with Hectochelle on the MMT will be used to supplement the information for many of the most interesting targets. The KIC will be released before launch for use by the astronomical community and will be available for queries over the internet. Support from the Kepler mission is gratefully acknowledged.

  3. Model-Free importance indicators for dependent input

    Energy Technology Data Exchange (ETDEWEB)

    Saltelli, A.; Ratto, M.; Tarantola, S

    2001-07-01

    A number of methods are available to asses uncertainty importance in the predictions of a simulation model for orthogonal sets of uncertain input factors. However, in many practical cases input factors are correlated. Even for these cases it is still possible to compute the correlation ratio and the partial (or incremental) importance measure, two popular sensitivity measures proposed in the recent literature on the subject. Unfortunately, the existing indicators of importance have limitations in terms of their use in sensitivity analysis of model output. Correlation ratios are indeed effective for priority setting (i.e. to find out what input factor needs better determination) but not, for instance, for the identification of the subset of the most important input factors, or for model simplification. In such cases other types of indicators are required that can cope with the simultaneous occurrence of correlation and interaction (a property of the model) among the input factors. In (1) the limitations of current measures of importance were discussed and a general approach was identified to quantify uncertainty importance for correlated inputs in terms of different betting contexts. This work was later submitted to the Journal of the American Statistical Association. However, the computational cost of such approach is still high, as it happens when dealing with correlated input factors. In this paper we explore how suitable designs could reduce the numerical load of the analysis. (Author) 11 refs.

  4. A robust hybrid model integrating enhanced inputs based extreme learning machine with PLSR (PLSR-EIELM) and its application to intelligent measurement.

    Science.gov (United States)

    He, Yan-Lin; Geng, Zhi-Qiang; Xu, Yuan; Zhu, Qun-Xiong

    2015-09-01

    In this paper, a robust hybrid model integrating an enhanced inputs based extreme learning machine with the partial least square regression (PLSR-EIELM) was proposed. The proposed PLSR-EIELM model can overcome two main flaws in the extreme learning machine (ELM), i.e. the intractable problem in determining the optimal number of the hidden layer neurons and the over-fitting phenomenon. First, a traditional extreme learning machine (ELM) is selected. Second, a method of randomly assigning is applied to the weights between the input layer and the hidden layer, and then the nonlinear transformation for independent variables can be obtained from the output of the hidden layer neurons. Especially, the original input variables are regarded as enhanced inputs; then the enhanced inputs and the nonlinear transformed variables are tied together as the whole independent variables. In this way, the PLSR can be carried out to identify the PLS components not only from the nonlinear transformed variables but also from the original input variables, which can remove the correlation among the whole independent variables and the expected outputs. Finally, the optimal relationship model of the whole independent variables with the expected outputs can be achieved by using PLSR. Thus, the PLSR-EIELM model is developed. Then the PLSR-EIELM model served as an intelligent measurement tool for the key variables of the Purified Terephthalic Acid (PTA) process and the High Density Polyethylene (HDPE) process. The experimental results show that the predictive accuracy of PLSR-EIELM is stable, which indicate that PLSR-EIELM has good robust character. Moreover, compared with ELM, PLSR, hierarchical ELM (HELM), and PLSR-ELM, PLSR-EIELM can achieve much smaller predicted relative errors in these two applications.

  5. Serial Input Output

    Energy Technology Data Exchange (ETDEWEB)

    Waite, Anthony; /SLAC

    2011-09-07

    Serial Input/Output (SIO) is designed to be a long term storage format of a sophistication somewhere between simple ASCII files and the techniques provided by inter alia Objectivity and Root. The former tend to be low density, information lossy (floating point numbers lose precision) and inflexible. The latter require abstract descriptions of the data with all that that implies in terms of extra complexity. The basic building blocks of SIO are streams, records and blocks. Streams provide the connections between the program and files. The user can define an arbitrary list of streams as required. A given stream must be opened for either reading or writing. SIO does not support read/write streams. If a stream is closed during the execution of a program, it can be reopened in either read or write mode to the same or a different file. Records represent a coherent grouping of data. Records consist of a collection of blocks (see next paragraph). The user can define a variety of records (headers, events, error logs, etc.) and request that any of them be written to any stream. When SIO reads a file, it first decodes the record name and if that record has been defined and unpacking has been requested for it, SIO proceeds to unpack the blocks. Blocks are user provided objects which do the real work of reading/writing the data. The user is responsible for writing the code for these blocks and for identifying these blocks to SIO at run time. To write a collection of blocks, the user must first connect them to a record. The record can then be written to a stream as described above. Note that the same block can be connected to many different records. When SIO reads a record, it scans through the blocks written and calls the corresponding block object (if it has been defined) to decode it. Undefined blocks are skipped. Each of these categories (streams, records and blocks) have some characteristics in common. Every stream, record and block has a name with the condition that each

  6. Score Correlation

    OpenAIRE

    Fabián, Z. (Zdeněk)

    2010-01-01

    In this paper, we study a distribution-dependent correlation coefficient based on the concept of scalar score. This new measure of association of continuous random variables is compared by means of simulation experiments with the Pearson, Kendall and Spearman correlation coefficients.

  7. Short-term beat-to-beat variability of the QT interval is increased and correlates with parameters of left ventricular hypertrophy in patients with hypertrophic cardiomyopathy.

    Science.gov (United States)

    Orosz, Andrea; Baczkó, István; Nagy, Viktória; Gavallér, Henriette; Csanády, Miklós; Forster, Tamás; Papp, Julius Gy; Varró, András; Lengyel, Csaba; Sepp, Róbert

    2015-09-01

    Stratification models for the prediction of sudden cardiac death (SCD) are inappropriate in patients with hypertrophic cardiomyopathy (HCM). We investigated conventional electrocardiogram (ECG) repolarization parameters and the beat-to-beat short-term QT interval variability (QT-STV), a new parameter of proarrhythmic risk, in 37 patients with HCM (21 males, average age 48 ± 15 years). Resting ECGs were recorded for 5 min and the frequency corrected QT interval (QTc), QT dispersion (QTd), beat-to-beat short-term variability of QT interval (QT-STV), and the duration of terminal part of T waves (Tpeak-Tend) were calculated. While all repolarization parameters were significantly increased in patients with HCM compared with the controls (QTc, 488 ± 61 vs. 434 ± 23 ms, p < 0.0001; QT-STV, 4.5 ± 2 vs. 3.2 ± 1 ms, p = 0.0002; Tpeak-Tend duration, 107 ± 27 vs. 91 ± 10 ms, p = 0.0015; QTd, 47 ± 17 vs. 34 ± 9 ms, p = 0.0002), QT-STV had the highest relative increase (+41%). QT-STV also showed the best correlation with indices of left ventricular (LV) hypertrophy, i.e., maximal LV wall thickness normalized for body surface area (BSA; r = 0.461, p = 0.004) or LV mass (determined by cardiac magnetic resonance imaging) normalized for BSA (r = 0.455, p = 0.015). In summary, beat-to-beat QT-STV showed the most marked increase in patients with HCM and may represent a novel marker that merits further testing for increased SCD risk in HCM.

  8. Evidence for variable, correlated X-ray and optical/IR extinction towards the nearby, pre-main-sequence binary TWA 30

    Science.gov (United States)

    Principe, David A.; Sacco, G.; Kastner, J. H.; Stelzer, B.; Alcalá, J. M.

    2016-06-01

    We present contemporaneous XMM-Newton X-ray and ground-based optical/near-IR spectroscopic observations of the nearby (D ≈ 42 pc), low-mass (mid-M) binary system TWA 30A and 30B. The components of this wide (separation ˜3400 au) binary are notable for their nearly edge-on disc viewing geometries, high levels of variability, and evidence for collimated stellar outflows. We obtained XMM-Newton X-ray observations of TWA 30A and 30B in 2011 June and July, accompanied (respectively) by Infrared Telescope Facility SpeX (near-IR) and VLT XSHOOTER (visible/near-IR) spectroscopy obtained within ˜20 h of the X-ray observations. TWA 30A was detected in both XMM-Newton observations at relatively faint intrinsic X-ray luminosities (LX ˜ 8 × 1027 erg s-1) compared to stars of similar mass and age. The intrinsic (0.15-2.0 keV) X-ray luminosities measured in 2011 had decreased by a factor 20-100 relative to a 1990 (ROSAT) X-ray detection. TWA 30B was not detected, and we infer an upper limit on its X-ray Luminosity of LX ≲ 3.0 × 1027 erg s-1. We measured a decrease in visual extinction towards TWA 30A (from AV ≈ 14.9 to AV ≈ 4.7) between the two 2011 observing epochs, and we find evidence for a corresponding significant decrease in X-ray absorbing column (NH). The apparent correlated change in AV and NH is suggestive of variable obscuration of the stellar photosphere by disc material composed of both gas and dust. However, in both observations, the inferred NH to AV ratio is lower than that typical of the interstellar medium, suggesting that the disc is either depleted of gas or is deficient in metals in the gas phase.

  9. Correlation between skin temperature and heart rate during exercise and recovery, and the influence of body position in these variables in untrained women

    Science.gov (United States)

    Neves, Eduardo Borba; Cunha, Raphael Martins; Rosa, Claudio; Antunes, Natacha Sousa; Felisberto, Ivo Miguel Vieira; Vilaça-Alves, José; Reis, Victor Machado

    2016-03-01

    It was known that the thermal response varies according to some variables. Until now, there are no studies that have investigated the relationship of skin temperature and heart rate during and after the workout, either the thermal behavior during postural changes. Objective: the aim of this study was to evaluate the behavior of skin temperature and heart rate, during exercise and up to an hour of recovery (with postural change), performed in two different intensities sessions (70% and 85% of 10 repetitions maximum) and observe the correlation between them. Method: This was a short longitudinal study, carried out with women aged from 18 to 30 years. A sample of 31 untrained women, aged 18 and 30 was used. The volunteers were randomized into two groups: Biceps Group (BG), with 15 women, and Quadriceps Group (QG) with 16 women. Results: During and after completion of the exercise session, there was a significant reduction in skin temperature on the active muscles in both groups (BG and QG), with similar thermal responses for the two intensities studied (70% and 85%) to the minute 15 (which marks the end of the recovery in the standing position). From minute 15 to minute 20-60, the skin temperature increases abruptly and significantly, returning to levels close to those observed before exercise. Conclusion: There were no statistical differences in thermal response to exercises in 70% or 85% of 10RM. There is a negative correlation between heart rate and skin temperature when untrained women perform anaerobic exercise. It was observed that after a change of posture (from a standing position to a sitting posture) skin temperature increased abruptly and significantly.

  10. National IQs: A Review of Their Educational, Cognitive, Economic, Political, Demographic, Sociological, Epidemiological, Geographic and Climatic Correlates

    Science.gov (United States)

    Lynn, Richard; Vanhanen, Tatu

    2012-01-01

    This paper summarizes the results of 244 correlates of national IQs that have been published from 2002 through 2012 and include educational attainment, cognitive output, educational input, per capita income, economic growth, other economic variables, crime, political institutions, health, fertility, sociological variables, and geographic and…

  11. National IQs: A Review of Their Educational, Cognitive, Economic, Political, Demographic, Sociological, Epidemiological, Geographic and Climatic Correlates

    Science.gov (United States)

    Lynn, Richard; Vanhanen, Tatu

    2012-01-01

    This paper summarizes the results of 244 correlates of national IQs that have been published from 2002 through 2012 and include educational attainment, cognitive output, educational input, per capita income, economic growth, other economic variables, crime, political institutions, health, fertility, sociological variables, and geographic and…

  12. Biometric verification with correlation filters

    Science.gov (United States)

    Vijaya Kumar, B. V. K.; Savvides, Marios; Xie, Chunyan; Venkataramani, Krithika; Thornton, Jason; Mahalanobis, Abhijit

    2004-01-01

    Using biometrics for subject verification can significantly improve security over that of approaches based on passwords and personal identification numbers, both of which people tend to lose or forget. In biometric verification the system tries to match an input biometric (such as a fingerprint, face image, or iris image) to a stored biometric template. Thus correlation filter techniques are attractive candidates for the matching precision needed in biometric verification. In particular, advanced correlation filters, such as synthetic discriminant function filters, can offer very good matching performance in the presence of variability in these biometric images (e.g., facial expressions, illumination changes, etc.). We investigate the performance of advanced correlation filters for face, fingerprint, and iris biometric verification.

  13. Input in Second Language Acquisition.

    Science.gov (United States)

    Gass, Susan M., Ed.; Madden, Carolyn G., Ed.

    This collection of conference papers includes: "When Does Teacher Talk Work as Input?"; "Cultural Input in Second Language Learning"; "Skilled Variation in a Kindergarten Teacher's Use of Foreigner Talk"; "Teacher-Pupil Interaction in Second Language Development"; "Foreigner Talk in the University…

  14. Inputs for L2 Acquisition.

    Science.gov (United States)

    Saleemi, Anjum P.

    1989-01-01

    Major approaches of describing or examining linguistic data from a potential target language (input) are analyzed for adequacy in addressing the concerns of second language learning theory. Suggestions are made for making the best of these varied concepts of input and for reformulation of a unified concept. (MSE)

  15. Input and Second Language Acquisition

    Institute of Scientific and Technical Information of China (English)

    周笑盈

    2011-01-01

    The behaviorist, the mentalist and the interactionist have different emphases on the role input in Second Language Acquisition. In order to protrude the importance of second language teaching, it is indispensible to discuss the characteristics of input and to explore its effects.

  16. Exact integral constraint requiring only the ground-state electron density as input on the exchange-correlation force - partial differential(V)(xc)(r)/partial differential(r) for spherical atoms.

    Science.gov (United States)

    March, N H; Nagy, A

    2008-11-21

    Following some studies of integral(n)(r)inverted DeltaV(r)dr by earlier workers for the density functional theory (DFT) one-body potential V(r) generating the exact ground-state density, we consider here the special case of spherical atoms. The starting point is the differential virial theorem, which is used, as well as the Hiller-Sucher-Feinberg [Phys. Rev. A 18, 2399 (1978)] identity to show that the scalar quantity paralleling the above vector integral, namely, integral(n)(r) partial differential(V)(r)/partial differential(r)dr, is determined solely by the electron density n(0) at the nucleus for the s-like atoms He and Be. The force - partial differential(V)/ partial differential(r) is then related to the derivative of the exchange-correlation potential V(xc)(r) by terms involving only the external potential in addition to n(r). The resulting integral constraint should allow some test of the quality of currently used forms of V(xc)(r). The article concludes with results from the differential virial theorem and the Hiller-Sucher-Feinberg identity for the exact many-electron theory of spherical atoms, as well as for the DFT for atoms such as Ne with a closed p shell.

  17. Utilizing time-lapse micro-CT-correlated bisphosphonate binding kinetics and soft tissue-derived input functions to differentiate site-specific changes in bone metabolism in vivo.

    Science.gov (United States)

    Tower, R J; Campbell, G M; Müller, M; Glüer, C C; Tiwari, S

    2015-05-01

    The turnover of bone is a tightly regulated process between bone formation and resorption to ensure skeletal homeostasis. This process differs between bone types, with trabecular bone often associated with higher turnover than cortical bone. Analyses of bone by micro-computed tomography (micro-CT) reveal changes in structure and mineral content, but are limited in the study of metabolic activity at a single time point, while analyses of serum markers can reveal changes in bone metabolism, but cannot delineate the origin of any aberrant findings. To obtain a site-specific assessment of bone metabolic status, bisphosphonate binding kinetics were utilized. Using a fluorescently-labeled bisphosphonate, we show that early binding kinetics monitored in vivo using fluorescent molecular tomography (FMT) can monitor changes in bone metabolism in response to bone loss, stimulated by ovariectomy (OVX), or bone gain, resulting from treatment with the anabolic bone agent parathyroid hormone (PTH), and is capable of distinguishing different, metabolically distinct skeletal sites. Using time-lapse micro-CT, longitudinal bone turnover was quantified. The spine showed a significantly greater percent resorbing volume and surface in response to OVX, while mice treated with PTH showed significantly greater resorbing volume per bone surface in the spine and significantly greater forming surfaces in the knee. Correlation studies between binding kinetics and micro-CT suggest that forming surfaces, as assessed by time-lapse micro-CT, are preferentially reflected in the rate constant values while forming and resorbing bone volumes primarily affect plateau values. Additionally, we developed a blood pool correction method which now allows for quantitative multi-compartment analyses to be conducted using FMT. These results further expand our understanding of bisphosphonate binding and the use of bisphosphonate binding kinetics as a tool to monitor site-specific changes in bone metabolism in

  18. Does Input Quality Drive Measured Differences in Firm Productivity?

    DEFF Research Database (Denmark)

    Fox, Jeremy T.; Smeets, Valerie Anne Rolande

    2011-01-01

    One explanation for productivity dispersion is that the quality of inputs differs across firms. We add labor market history variables such as experience and firm and industry tenure, as well as general human capital measures such as schooling and sex. Adding these variables decreases the ratio of...

  19. Input saturation in nonlinear multivariable processes resolved by nonlinear decoupling

    Directory of Open Access Journals (Sweden)

    Jens G. Balchen

    1995-04-01

    Full Text Available A new method is presented for the resolution of the problem of input saturation in nonlinear multivariable process control by means of elementary nonlinear decoupling (END. Input saturation can have serious consequences particularly in multivariable control because it may lead to very undesirable system behaviour and quite often system instability. Many authors have searched for systematic techniques for designing multivariable control systems in which saturation may occur in any of the control variables (inputs, manipulated variables. No generally accepted method seems to have been presented so far which gives a solution in closed form. The method of elementary nonlinear decoupling (END can be applied directly to the case of saturation control variables by deriving as many control strategies as there are combinations of saturating control variables. The method is demonstrated by the multivariable control of a simulated Fluidized Catalytic Cracker (FCC with very convincing results.

  20. Seasonal and spatial variability of the OM/OC mass ratios and high regional correlation between oxalic acid and zinc in Chinese urban organic aerosols

    Science.gov (United States)

    Xing, L.; Fu, T.-M.; Cao, J. J.; Lee, S. C.; Wang, G. H.; Ho, K. F.; Cheng, M.-C.; You, C.-F.; Wang, T. J.

    2013-04-01

    We calculated the organic matter to organic carbon mass ratios (OM/OC mass ratios) in PM2.5 collected from 14 Chinese cities during summer and winter of 2003 and analyzed the causes for their seasonal and spatial variability. The OM/OC mass ratios were calculated two ways. Using a mass balance method, the calculated OM/OC mass ratios averaged 1.92 ± 0.39 year-round, with no significant seasonal or spatial variation. The second calculation was based on chemical species analyses of the organic compounds extracted from the PM2.5 samples using dichloromethane/methanol and water. The calculated OM/OC mass ratio in summer was relatively high (1.75 ± 0.13) and spatially-invariant due to vigorous photochemistry and secondary organic aerosol (OA) production throughout the country. The calculated OM/OC mass ratio in winter (1.59 ± 0.18) was significantly lower than that in summer, with lower values in northern cities (1.51 ± 0.07) than in southern cities (1.65 ± 0.15). This likely reflects the wider usage of coal for heating purposes in northern China in winter, in contrast to the larger contributions from biofuel and biomass burning in southern China in winter. On average, organic matter constituted 36% and 34% of Chinese urban PM2.5 mass in summer and winter, respectively. We report, for the first time, a high regional correlation between Zn and oxalic acid in Chinese urban aerosols in summer. This is consistent with the formation of stable Zn oxalate complex in the aerosol phase previously proposed by Furukawa and Takahashi (2011). We found that many other dicarboxylic acids were also highly correlated with Zn in the summer Chinese urban aerosol samples, suggesting that they may also form stable organic complexes with Zn. Such formation may have profound implications for the atmospheric abundance and hygroscopic properties of aerosol dicarboxylic acids.

  1. Input management of production systems.

    Science.gov (United States)

    Odum, E P

    1989-01-13

    Nonpoint sources of pollution, which are largely responsible for stressing regional and global life-supporting atmosphere, soil, and water, can only be reduced (and ultimately controlled) by input management that involves increasing the efficiency of production systems and reducing the inputs of environmentally damaging materials. Input management requires a major change, an about-face, in the approach to management of agriculture, power plants, and industries because the focus is on waste reduction and recycling rather than on waste disposal. For large-scale ecosystem-level situations a top-down hierarchical approach is suggested and illustrated by recent research in agroecology and landscape ecology.

  2. The correlation between effective factors of e-learning and demographic variables in a post-graduate program of virtual medical education in Tehran University of Medical Sciences.

    Directory of Open Access Journals (Sweden)

    Farnoosh Golband

    2014-11-01

    Full Text Available E-learning as an educational approach has been adopted by diverse educational and academic centers worldwide as it facilitates learning in facing the challenges of the new era in education. Considering the significance of virtual education and its growing practice, it is of vital importance to examine its components for promoting and maintaining success. This analytical cross-sectional study was an attempt to determine the relationship between four factors of content, educator, learner and system, and effective e-learning in terms of demographic variables, including age, gender, educational background, and marital status of postgraduate master's students (MSc studying at virtual faculty of Tehran University of Medical Sciences. The sample was selected by census (n=60; a demographic data gathering tool and a researcher-made questionnaire were used to collect data. The face and content validity of both tools were confirmed and the results were analyzed by descriptive statistics (frequency, percentile, standard deviation and mean and inferential statistics (independent t-test, Scheffe's test, one-way ANOVA and Pearson correlation test by using SPSS (V.16. The present study revealed that There was no statistically significant relationship between age and marital status and effective e-learning (P>0.05; whereas, there was a statistically significant difference between gender and educational background with effective e-learning (P<0.05. Knowing the extent to which these factors can influence effective e-learning can help managers and designers to make the right decisions about educational components of e-learning, i.e. content, educator, system and learner and improve them to create a more productive learning environment for learners.

  3. The expression of immunohistochemical markers estrogen receptor, progesterone receptor, Her-2-neu, p53 and Ki-67 in epithelial ovarian tumors and its correlation with clinicopathologic variables

    Directory of Open Access Journals (Sweden)

    Mary T Sylvia

    2012-01-01

    Full Text Available Background: This study aims to evaluate the expression of estrogen receptor alpha (ER α, progesterone receptor A (PRA, Her-2-neu, p53, and Ki-67 in epithelial ovarian tumors and their correlation with various clinicopathologic variables. Materials and Methods: This study included 60 consecutive cases of epithelial ovarian tumors. Sections of 4 μm were taken from paraffin embedded tissue blocks for immunohistochemistry (IHC. Statistical analysis was done using Chi square test, ANOVA. Results: ER α had lower expression in benign (29% and PRA higher expression in malignant (63.6% tumors. ERα, PRA had higher expression in serous (72.72%, 57.14%, postmenopausal (81.8%, 71.42%, advanced stage (63.63%, 52.38%, grade 3 (45.45%, 38.09%, and tumors with ascites (90.90%, 85.7%. Her-2-neu, p53 were negative in benign and higher in malignant (21%, 57.6%, serous (71.42%, 57.89%, grade 3 (57.14%, 31.57%, and tumors with ascites (85.7%, 84.21%. Ki-67 had a significant higher expression in malignant (48.6± 26.76, serous (55.43± 27.85, and grade 3 tumors (68 ± 22. CA-125 levels were significantly higher in malignant, serous, advanced stage, grade 3 and ER α, Her-2-neu and p53 positive tumors. Conclusion: ERα, PRA expression in tumors with adverse prognostic factors support the mitogenic role of estrogen and estrogenic regulation of PR. Her-2-neu and p53 expression only in malignant tumors suggest their carcinogenic role and aid in the differentiation of borderline and malignant tumors. Higher Ki-67 in tumors with adverse prognostic factors would help in prognostication and differentiation. Lack of co-expression of markers proves the extreme heterogeneity of ovarian tumors. These markers may aid in differentiation and prognostication of ovarian tumors.

  4. NEW EQUATION FOR CORRELATING EXPERIMENTAL DATA WITH TWO VARIABLES%双自变量化学化工实验数据的新拟合方程

    Institute of Scientific and Technical Information of China (English)

    盛景云; 方维平; 王跃敏

    2004-01-01

    The equation mostly used for correlating experimental data is normal polynomial: f(x, t)=co(t)+c1 (t)x+c2 (t)x2+…+cn(t)xm. However correlation with this polynomial is undesirable when the curved surface formed by experimental data is not smooth or the correlating range of correlation is too large. In this paper, a new correlating equation for this purpose is proposed. There are no undetermined coefficients in the new equation. When this new equation is used for correlating different kinds of experimental data (curved surface), smaller errors will always be obtained in comparison with the normal polynomial.

  5. Variable input parameter influence on river corridor prediction

    NARCIS (Netherlands)

    Zerfu, T.; Beevers, L.; Crosato, A.; Wright, N.

    2015-01-01

    This paper considers the erodible river corridor, which is the area in which the main river channel is free to migrate over a period of time. Due to growing anthropogenic pressure, predicting the corridor width has become increasingly important for the planning of development along rivers. Several a

  6. The Advanced LIGO Input Optics

    CERN Document Server

    Mueller, Chris; Ciani, Giacomo; DeRosa, Ryan; Effler, Anamaria; Feldbaum, David; Frolov, Valery; Fulda, Paul; Gleason, Joseph; Heintze, Matthew; King, Eleanor; Kokeyama, Keiko; Korth, William; Martin, Rodica; Mullavey, Adam; Poeld, Jan; Quetschke, Volker; Reitze, David; Tanner, David; Williams, Luke; Mueller, Guido

    2016-01-01

    The Advanced LIGO gravitational wave detectors are nearing their design sensitivity and should begin taking meaningful astrophysical data in the fall of 2015. These resonant optical interferometers will have unprecedented sensitivity to the strains caused by passing gravitational waves. The input optics play a significant part in allowing these devices to reach such sensitivities. Residing between the pre-stabilized laser and the main interferometer, the input optics is tasked with preparing the laser beam for interferometry at the sub-attometer level while operating at continuous wave input power levels ranging from 100 mW to 150 W. These extreme operating conditions required every major component to be custom designed. These designs draw heavily on the experience and understanding gained during the operation of Initial LIGO and Enhanced LIGO. In this article we report on how the components of the input optics were designed to meet their stringent requirements and present measurements showing how well they h...

  7. Nonlinear input-output systems

    Science.gov (United States)

    Hunt, L. R.; Luksic, Mladen; Su, Renjeng

    1987-01-01

    Necessary and sufficient conditions that the nonlinear system dot-x = f(x) + ug(x) and y = h(x) be locally feedback equivalent to the controllable linear system dot-xi = A xi + bv and y = C xi having linear output are found. Only the single input and single output case is considered, however, the results generalize to multi-input and multi-output systems.

  8. When Can Information from Ordinal Scale Variables Be Integrated?

    Science.gov (United States)

    Kemp, Simon; Grace, Randolph C.

    2010-01-01

    Many theoretical constructs of interest to psychologists are multidimensional and derive from the integration of several input variables. We show that input variables that are measured on ordinal scales cannot be combined to produce a stable weakly ordered output variable that allows trading off the input variables. Instead a partial order is…

  9. Reliability Analysis of Gravity Dam Foundation Surface's Sliding Stability under Considering Variable Correlation%考虑变量相关的重力坝建基面抗滑稳定可靠度分析

    Institute of Scientific and Technical Information of China (English)

    欧阳彬生; 罗琳

    2011-01-01

    In the reliability analysis for sliding stability of gravity dam foundation surface, there exists the correlation relationship between the anti-cut friction coefficient and cohesion. Considering the variables being more in line with the actuai situation of the project, the rehable indication from calculation is higher. Here, the concept and treatment method of variable correlation are introduced, the corresponding program is written, and the reliability indexes of the sliding stability are calculated under two conditions with and without considering the variable correlation. The results show that trader considering the variable correlation, the reliability index would be decreased relatively to a great extent.%在重力坝建基面抗滑稳定可靠度计算中,抗剪断摩擦系数和凝聚力存在相关关系.考虑变量相关更加符合工程实际情况,计算得到的可靠指标可信度更高.本文介绍了变量相关的概念和处理方法,编制了相应的计算程序,计算了考虑和不考虑变量相关两种工况的抗滑稳定可靠指标.计算结果表明,考虑变量相关后,可靠指标有较大程度的降低.

  10. Research on the Relation Between the Innovation Input and Output of the Regional Innovation System Based on the Canonical Correlation Analysis%基于典型相关分析的区域创新系统投入与产出关系研究

    Institute of Scientific and Technical Information of China (English)

    于明洁; 郭鹏

    2012-01-01

    Taking the relation between innovation input and output of the regional innovation system as the research object, the paper conducts empirical research based on the canonical correlation analysis method. The result shows that, there are strong correlation among the innovation input and output, the number of whole time research and development personnel has significant effects on the invention patent, the national innovation fund has significant effects on the new products sales income of the enterprises, the fixed asset per capita has inhibitory effects on both the number of the High-Tech Enterprise and the new products sales income of the enterprises, the number of research and development personnel in the industrial ventures above the scale has significant effects on both the High-Tech Enterprise and the new products sales income of the enterprises. Finally, some policy suggestions are offered in accordance with the research result.%国家软科学研究计划项目“陕西航空产业集群发展战略研究”(2010GXS5D264);西安市软科学研究计划项目“面向国际化大都市的西安市产学研创新系统协调发展研究”(HJll08—3);西北工业大学研究生创业种子基金项目“区域创新系统协调性与区域创新能力关系研究”(Z2011126)

  11. Novel multiplex format of an extended multilocus variable-number-tandem-repeat analysis of Clostridium difficile correlates with tandem repeat sequence typing.

    Science.gov (United States)

    Jensen, Mie Birgitte Frid; Engberg, Jørgen; Larsson, Jonas T; Olsen, Katharina E P; Torpdahl, Mia

    2015-03-01

    Subtyping of Clostridium difficile is crucial for outbreak investigations. An extended multilocus variable-number tandem-repeat analysis (eMLVA) of 14 variable number tandem repeat (VNTR) loci was validated in multiplex format compatible with a routine typing laboratory and showed excellent concordance with tandem repeat sequence typing (TRST) and high discriminatory power.

  12. Ensemble standar deviation of wind speed and direction of the FDDA input to WRF

    Data.gov (United States)

    U.S. Environmental Protection Agency — NetCDF file of the SREF standard deviation of wind speed and direction that was used to inject variability in the FDDA input. variable U_NDG_OLD contains standard...

  13. COGNITIVE INTERPRETATION OF INPUT HYPOTHESIS

    Institute of Scientific and Technical Information of China (English)

    WangHongyue; RenLiankui

    2004-01-01

    Krashen's Input Hypothesis, together with its earlier version, the Monitor Model is an influential theory in Second Language Acquisition research. In his studies, Krashen, on the one hand, emphasizes the part '“ comprehensible input” plays in learning a second language, on the other hand, he simply defines“comprehensible input” as “a little beyond the learner's current level”. What input can be considered as“a little beyond the learner's current level ”? Krashen gives no furtherexplanation. This paper tries to offer a more concrete and more detailed interpretation with Ausubel's Cognitive Assimilation theory.

  14. Input Hypothesis and its Controversy

    Institute of Scientific and Technical Information of China (English)

    金灵

    2016-01-01

    With Krashen's proposal of input hypothesis in 1980s, lots of contributions and further researches have been done in second language acquisition and teaching. Since it is impossible to undertake the exact empirical research to investigate its credibility, lots of criticisms are also aroused to disprove or adjust this hypothesis. However, due to its significant development in SLA, it is still valuable to explore the hypothesis and implications in language teaching to non-native speakers. This paper firstly focuses on the development of the input hypothesis, and then discusses some criticisms of this hypothesis.

  15. Variabilidade genética e correlações entre caracteres de feijão-caupi = Genetic variability and correlations between characters in cowpea

    Directory of Open Access Journals (Sweden)

    Agenor Martinho Correa

    2015-03-01

    which characters can be used for selection of superior genotypes. The experiment was conducted at the Universidade Estadual do Mato Grosso do Sul, in Aquidauna, during “dry” years of 2009. The treatments consisted of 20 genotypes of cowpea, 11 cultivars (Canapuzinho, Canapuzinho-2, Inhuma, Pingoof-gold-1-2, Pingo-of-gold-2, Paulistinha, Patativa, Paraguassu-BRS, BRS-Millennium, BR17-Gurguéia and BRS-Marataoã and 9 strains (MNC99-510F-16-1, MNC99-510F-16-3, MNC99-537F-14-2, MNC01-611F-11, MNC01-614F-15, MNC01-631F-11, MNC01-631F-15, MNC01-631F-20-5, MNC01-649E-2. The experimental design was a completely randomized block design with four replications. It was evaluated the characters: early flowering, early maturation, mass of 100 grains, green pod length, green pod mass, number of grains per pod and dry yield grains. To verify the existence of variability between genotypes, data were subjected to analysis of variance by F-test. Subsequently, it was determined following genetic parameters: environmental variance, phenotypic and genotypic; experimental and genotypic coefficient of variation; genotypic coefficient of determination; quotient b; environmental, phenotypic and genetic correlations. The population presents genetic variability and potential for genetic improvement. Based on the evaluated parameters, the breeding programs in cowpea can perform the selection of genotypes based on the characters: days to maturity, green mass of pods, number of seeds per pod and grain yield.

  16. Sensory Synergy as Environmental Input Integration

    Directory of Open Access Journals (Sweden)

    Fady eAlnajjar

    2015-01-01

    Full Text Available The development of a method to feed proper environmental inputs back to the central nervous system (CNS remains one of the challenges in achieving natural movement when part of the body is replaced with an artificial device. Muscle synergies are widely accepted as a biologically plausible interpretation of the neural dynamics between the CNS and the muscular system. Yet the sensorineural dynamics of environmental feedback to the CNS has not been investigated in detail. In this study, we address this issue by exploring the concept of sensory synergy. In contrast to muscle synergy, we hypothesize that sensory synergy plays an essential role in integrating the overall environmental inputs to provide low-dimensional information to the CNS. We assume that sensor synergy and muscle synergy communicate using these low-dimensional signals. To examine our hypothesis, we conducted posture control experiments involving lateral disturbance with 9 healthy participants. Proprioceptive information represented by the changes on muscle lengths were estimated by using the musculoskeletal model analysis software SIMM. Changes on muscles lengths were then used to compute sensory synergies. The experimental results indicate that the environmental inputs were translated into the two dimensional signals and used to move the upper limb to the desired position immediately after the lateral disturbance. Participants who showed high skill in posture control were found to be likely to have a strong correlation between sensory and muscle signaling as well as high coordination between the utilized sensory synergies. These results suggest the importance of integrating environmental inputs into suitable low-dimensional signals before providing them to the CNS. This mechanism should be essential when designing the prosthesis’ sensory system to make the controller simpler

  17. Preisach models of hysteresis driven by Markovian input processes

    Science.gov (United States)

    Schubert, Sven; Radons, Günter

    2017-08-01

    We study the response of Preisach models of hysteresis to stochastically fluctuating external fields. We perform numerical simulations, which indicate that analytical expressions derived previously for the autocorrelation functions and power spectral densities of the Preisach model with uncorrelated input, hold asymptotically also if the external field shows exponentially decaying correlations. As a consequence, the mechanisms causing long-term memory and 1 /f noise in Preisach models with uncorrelated inputs still apply in the presence of fast decaying input correlations. We collect additional evidence for the importance of the effective Preisach density previously introduced even for Preisach models with correlated inputs. Additionally, we present some results for the output of the Preisach model with uncorrelated input using analytical methods. It is found, for instance, that in order to produce the same long-time tails in the output, the elementary hysteresis loops of large width need to have a higher weight for the generic Preisach model than for the symmetric Preisach model. Further, we find autocorrelation functions and power spectral densities to be monotonically decreasing independently of the choice of input and Preisach density.

  18. Neural Variability Quenching Predicts Individual Perceptual Abilities.

    Science.gov (United States)

    Arazi, Ayelet; Censor, Nitzan; Dinstein, Ilan

    2017-01-04

    Neural activity during repeated presentations of a sensory stimulus exhibits considerable trial-by-trial variability. Previous studies have reported that trial-by-trial neural variability is reduced (quenched) by the presentation of a stimulus. However, the functional significance and behavioral relevance of variability quenching and the potential physiological mechanisms that may drive it have been studied only rarely. Here, we recorded neural activity with EEG as subjects performed a two-interval forced-choice contrast discrimination task. Trial-by-trial neural variability was quenched by ∼40% after the presentation of the stimulus relative to the variability apparent before stimulus presentation, yet there were large differences in the magnitude of variability quenching across subjects. Individual magnitudes of quenching predicted individual discrimination capabilities such that subjects who exhibited larger quenching had smaller contrast discrimination thresholds and steeper psychometric function slopes. Furthermore, the magnitude of variability quenching was strongly correlated with a reduction in broadband EEG power after stimulus presentation. Our results suggest that neural variability quenching is achieved by reducing the amplitude of broadband neural oscillations after sensory input, which yields relatively more reproducible cortical activity across trials and enables superior perceptual abilities in individuals who quench more.

  19. Hybrid input function estimation using a single-input-multiple-output (SIMO) approach

    Science.gov (United States)

    Su, Yi; Shoghi, Kooresh I.

    2009-02-01

    A hybrid blood input function (BIF) model that incorporates region of interests (ROIs) based peak estimation and a two exponential tail model was proposed to describe the blood input function. The hybrid BIF model was applied to the single-input-multiple-output (SIMO) optimization based approach for BIF estimation using time activity curves (TACs) obtained from ROIs defined at left ventricle (LV) blood pool and myocardium regions of dynamic PET images. The proposed BIF estimation method was applied with 0, 1 and 2 blood samples as constraints for BIF estimation using simulated small animal PET data. Relative percentage difference of the area-under-curve (AUC) measurement between the estimated BIF and the true BIF was calculated to evaluate the BIF estimation accuracy. SIMO based BIF estimation using Feng's input function model was also applied for comparison. The hybrid method provided improved BIF estimation in terms of both mean accuracy and variability compared to Feng's model based BIF estimation in our simulation study. When two blood samples were used as constraints, the percentage BIF estimation error was 0.82 +/- 4.32% for the hybrid approach and 4.63 +/- 10.67% for the Feng's model based approach. Using hybrid BIF, improved kinetic parameter estimation was also obtained.

  20. 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.

  1. World Input-Output Network.

    Directory of Open Access Journals (Sweden)

    Federica Cerina

    Full Text Available Production systems, traditionally analyzed as almost independent national systems, are increasingly connected on a global scale. Only recently becoming available, the World Input-Output Database (WIOD is one of the first efforts to construct the global multi-regional input-output (GMRIO tables. By viewing the world input-output system as an interdependent network where the nodes are the individual industries in different economies and the edges are the monetary goods flows between industries, we analyze respectively the global, regional, and local network properties of the so-called world input-output network (WION and document its evolution over time. At global level, we find that the industries are highly but asymmetrically connected, which implies that micro shocks can lead to macro fluctuations. At regional level, we find that the world production is still operated nationally or at most regionally as the communities detected are either individual economies or geographically well defined regions. Finally, at local level, for each industry we compare the network-based measures with the traditional methods of backward linkages. We find that the network-based measures such as PageRank centrality and community coreness measure can give valuable insights into identifying the key industries.

  2. On Adaptive Optimal Input Design

    NARCIS (Netherlands)

    Stigter, J.D.; Vries, D.; Keesman, K.J.

    2003-01-01

    The problem of optimal input design (OID) for a fed-batch bioreactor case study is solved recursively. Here an adaptive receding horizon optimal control problem, involving the so-called E-criterion, is solved on-line, using the current estimate of the parameter vector at each sample instant {tk, k =

  3. World Input-Output Network

    Science.gov (United States)

    Cerina, Federica; Zhu, Zhen; Chessa, Alessandro; Riccaboni, Massimo

    2015-01-01

    Production systems, traditionally analyzed as almost independent national systems, are increasingly connected on a global scale. Only recently becoming available, the World Input-Output Database (WIOD) is one of the first efforts to construct the global multi-regional input-output (GMRIO) tables. By viewing the world input-output system as an interdependent network where the nodes are the individual industries in different economies and the edges are the monetary goods flows between industries, we analyze respectively the global, regional, and local network properties of the so-called world input-output network (WION) and document its evolution over time. At global level, we find that the industries are highly but asymmetrically connected, which implies that micro shocks can lead to macro fluctuations. At regional level, we find that the world production is still operated nationally or at most regionally as the communities detected are either individual economies or geographically well defined regions. Finally, at local level, for each industry we compare the network-based measures with the traditional methods of backward linkages. We find that the network-based measures such as PageRank centrality and community coreness measure can give valuable insights into identifying the key industries. PMID:26222389

  4. Input in an Institutional Setting.

    Science.gov (United States)

    Bardovi-Harlig, Kathleen; Hartford, Beverly S.

    1996-01-01

    Investigates the nature of input available to learners in the institutional setting of the academic advising session. Results indicate that evidence for the realization of speech acts, positive evidence from peers and status unequals, the effect of stereotypes, and limitations of a learner's pragmatic and grammatical competence are influential…

  5. Optimal Inputs for System Identification.

    Science.gov (United States)

    1995-09-01

    The derivation of the power spectral density of the optimal input for system identification is addressed in this research. Optimality is defined in...identification potential of general System Identification algorithms, a new and efficient System Identification algorithm that employs Iterated Weighted Least

  6. Analog Input Data Acquisition Software

    Science.gov (United States)

    Arens, Ellen

    2009-01-01

    DAQ Master Software allows users to easily set up a system to monitor up to five analog input channels and save the data after acquisition. This program was written in LabVIEW 8.0, and requires the LabVIEW runtime engine 8.0 to run the executable.

  7. Remote input/output station

    CERN Multimedia

    1972-01-01

    A general view of the remote input/output station installed in building 112 (ISR) and used for submitting jobs to the CDC 6500 and 6600. The card reader on the left and the line printer on the right are operated by programmers on a self-service basis.

  8. World Input-Output Network.

    Science.gov (United States)

    Cerina, Federica; Zhu, Zhen; Chessa, Alessandro; Riccaboni, Massimo

    2015-01-01

    Production systems, traditionally analyzed as almost independent national systems, are increasingly connected on a global scale. Only recently becoming available, the World Input-Output Database (WIOD) is one of the first efforts to construct the global multi-regional input-output (GMRIO) tables. By viewing the world input-output system as an interdependent network where the nodes are the individual industries in different economies and the edges are the monetary goods flows between industries, we analyze respectively the global, regional, and local network properties of the so-called world input-output network (WION) and document its evolution over time. At global level, we find that the industries are highly but asymmetrically connected, which implies that micro shocks can lead to macro fluctuations. At regional level, we find that the world production is still operated nationally or at most regionally as the communities detected are either individual economies or geographically well defined regions. Finally, at local level, for each industry we compare the network-based measures with the traditional methods of backward linkages. We find that the network-based measures such as PageRank centrality and community coreness measure can give valuable insights into identifying the key industries.

  9. Input/output interface module

    Science.gov (United States)

    Ozyazici, E. M.

    1980-01-01

    Module detects level changes in any of its 16 inputs, transfers changes to its outputs, and generates interrupts when changes are detected. Up to four changes-in-state per line are stored for later retrieval by controlling computer. Using standard TTL logic, module fits 19-inch rack-mounted console.

  10. The advanced LIGO input optics

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Chris L., E-mail: cmueller@phys.ufl.edu; Arain, Muzammil A.; Ciani, Giacomo; Feldbaum, David; Fulda, Paul; Gleason, Joseph; Heintze, Matthew; Martin, Rodica M.; Reitze, David H.; Tanner, David B.; Williams, Luke F.; Mueller, Guido [University of Florida, Gainesville, Florida 32611 (United States); DeRosa, Ryan T.; Effler, Anamaria; Kokeyama, Keiko [Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Frolov, Valery V.; Mullavey, Adam [LIGO Livingston Observatory, Livingston, Louisiana 70754 (United States); Kawabe, Keita; Vorvick, Cheryl [LIGO Hanford Observatory, Richland, Washington 99352 (United States); King, Eleanor J. [University of Adelaide, Adelaide, SA 5005 (Australia); and others

    2016-01-15

    The advanced LIGO gravitational wave detectors are nearing their design sensitivity and should begin taking meaningful astrophysical data in the fall of 2015. These resonant optical interferometers will have unprecedented sensitivity to the strains caused by passing gravitational waves. The input optics play a significant part in allowing these devices to reach such sensitivities. Residing between the pre-stabilized laser and the main interferometer, the input optics subsystem is tasked with preparing the laser beam for interferometry at the sub-attometer level while operating at continuous wave input power levels ranging from 100 mW to 150 W. These extreme operating conditions required every major component to be custom designed. These designs draw heavily on the experience and understanding gained during the operation of Initial LIGO and Enhanced LIGO. In this article, we report on how the components of the input optics were designed to meet their stringent requirements and present measurements showing how well they have lived up to their design.

  11. Heart Rate Variability Analysis in General Medicine

    Directory of Open Access Journals (Sweden)

    Yi Gang

    2003-01-01

    Full Text Available Autonomic nervous system plays an integral role in homeostasis. Autonomic modulation can frequently be altered in patients with cardiac disorders as well as in patients with other critical illnesses or injuries. Assessment of heart rate variability is based on analysis of consecutive normal R-R intervals and may provide quantitative information on the modulation of cardiac vagal and sympathetic nerve input. The hypothesis that depressed heart rate variability may occur over a broad range of illness and injury, and may inversely correlated with disease severity and outcome has been tested in various clinical settings over the last decade. This article reviews recent literature concerning the potential clinical implications and limitations of heart rate variability assessment in general medicine.

  12. Continuous within-plant variation as a source of intraspecific functional diversity: Patterns, magnitude, and genetic correlates of leaf variability in Helleborus foetidus (Ranunculaceae).

    Science.gov (United States)

    Herrera, Carlos M; Medrano, Mónica; Bazaga, Pilar

    2015-02-01

    Continuous within-plant variation in quantitative traits of reiterated, homologous structures is a component of intraspecific variation, but its contribution to functional diversity remains largely unexplored. For the perennial Helleborus foetidus, we measured functional leaf traits to quantify the contribution of within-plant variation to intraspecific functional variance and evaluate whether within-plant variability itself deserves separate consideration. Within-individual variation in eight leaf traits was quantified for 138 plants sampled from 10 widely spaced locations in the Sierra de Cazorla, southeastern Spain. An amplified fragment length polymorphism (AFLP) technique was used to look for associations between within-plant variability and specific AFLP markers. Leaflets from basal positions in ramets were longer, heavier, had greater surface area and larger stomata, and lower specific area, stomatal index, and stomatal density than those from distal positions. Continuous variation between leaves from the same ramet was the main source of population-wide variance for most traits. Within-plant variability differed among populations. Individuals differed in within-plant variability, which was largely independent of trait means and associated with genetic characteristics. Up to four AFLP markers were associated with the within-plant variability level of a given leaf trait. Subindividual variability in continuous leaf traits was independent of plant means and related to genetic features. The within-individual component generally exceeded the between-individual component of intraspecific variance. Within-plant variation may broaden the ecological breadth and enhance stability and persistence of plant populations and communities and may provide novel insights when incorporated in trait-based community ecology models. © 2015 Botanical Society of America, Inc.

  13. Interneurons targeting similar layers receive synaptic inputs with similar kinetics.

    Science.gov (United States)

    Cossart, Rosa; Petanjek, Zdravko; Dumitriu, Dani; Hirsch, June C; Ben-Ari, Yehezkel; Esclapez, Monique; Bernard, Christophe

    2006-01-01

    GABAergic interneurons play diverse and important roles in controlling neuronal network dynamics. They are characterized by an extreme heterogeneity morphologically, neurochemically, and physiologically, but a functionally relevant classification is still lacking. Present taxonomy is essentially based on their postsynaptic targets, but a physiological counterpart to this classification has not yet been determined. Using a quantitative analysis based on multidimensional clustering of morphological and physiological variables, we now demonstrate a strong correlation between the kinetics of glutamate and GABA miniature synaptic currents received by CA1 hippocampal interneurons and the laminar distribution of their axons: neurons that project to the same layer(s) receive synaptic inputs with similar kinetics distributions. In contrast, the kinetics distributions of GABAergic and glutamatergic synaptic events received by a given interneuron do not depend upon its somatic location or dendritic arborization. Although the mechanisms responsible for this unexpected observation are still unclear, our results suggest that interneurons may be programmed to receive synaptic currents with specific temporal dynamics depending on their targets and the local networks in which they operate.

  14. Reconstruction of organochlorine compound inputs in the Tagus Prodelta.

    Science.gov (United States)

    Mil-Homens, Mário; Vicente, Maria; Grimalt, Joan O; Micaelo, Cristina; Abrantes, Fátima

    2016-01-01

    Twenty century time-resolved variability of riverine deposits of polychlorobiphenyls (PCBs), DDTs, hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) was studied in three (210)Pb dated sediment cores collected in a depositional shelf area adjacent to the Tagus estuary (the Tagus Prodelta). The geographic and temporal distribution patterns were consistent with discharge of these organochlorine compounds (OCs) in the area associated with the Tagus mouth. Their concentrations were not correlated with the sedimentary total organic carbon. The PCB down-core profiles were dominated by CB138 and CB153 (hexa-CBs) congeners followed by CB180 (hepta-CBs). Principal Component Analysis of the congener distributions of these compounds did not define temporal down-core trends. The ratios of DDT metabolites (p,p'-DDE/p,p'-DDT) were consistent with recent DDT inputs into the environment and/or earlier applications and long-term residence in soils/sediments until these were eroded and remobilized. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Path-Sensitive Multi-Variable Access Correlations Mining and Related Source Code Defects Detection%路径敏感的源码关联变量模式挖掘及缺陷检测

    Institute of Scientific and Technical Information of China (English)

    于秀梅; 梁彬; 陈红; 谢素斌; 王眉林

    2012-01-01

    A large number of widespread source systems make the security of source code of software increasingly important. Multi-variable access correlation rales are mined by the path-sensitive method and the defects caused by inconsistent access to correlated variables are detected automatically in the large-scale source code systems. Multi-variable access correlations can be mined via logical information of source code and sensitive path information, which avoids fault from the insensitive path method. The effective solutions to the uneven distribution of path weight and the path explosion problems are presented. The presented method is verified by Linux system, and the experimental result shows that it mines correct multi-variable access correlations.%大量而广泛存在的源码系统使得软件源码的安全问题日益重要.文中在大型源码系统中采取路径敏感的方式挖掘关联变量访问规则,并自动检测系统中因不一致访问关联变量引发的源码缺陷.通过结合程序源码的逻辑信息及路径敏感信息,挖掘出其中的源码关联变量,避免路径非敏感方法带来的错误.对路径敏感方法挖掘源码关联变量中面临的主要挑战:路径权重不均、路径爆炸问题,提出较高效的解决办法.在Linux源码系统中验证方法的正确性和高效性,实验结果表明该方法可高效、准确提取模式.

  16. Study of Chunks Input Approach

    Institute of Scientific and Technical Information of China (English)

    马静

    2003-01-01

    This paper is to describe and investigate Chunks (Lexical Phrases ) Input Approach in vocabulary learning strategies by means of achievement tests,questionnaire surveys and interviews. The study is to reveal how different learners combine different vocabulary learning strategies in their learning process. With the data collected, the author of this paper discusses and summarizes learners' individual differences in selecting vocabulary learning strategies with the hope of giving new insights into English teaching and learning.

  17. Distributed and Mixed Information in Monosynaptic Inputs to Dopamine Neurons.

    Science.gov (United States)

    Tian, Ju; Huang, Ryan; Cohen, Jeremiah Y; Osakada, Fumitaka; Kobak, Dmitry; Machens, Christian K; Callaway, Edward M; Uchida, Naoshige; Watabe-Uchida, Mitsuko

    2016-09-21

    Dopamine neurons encode the difference between actual and predicted reward, or reward prediction error (RPE). Although many models have been proposed to account for this computation, it has been difficult to test these models experimentally. Here we established an awake electrophysiological recording system, combined with rabies virus and optogenetic cell-type identification, to characterize the firing patterns of monosynaptic inputs to dopamine neurons while mice performed classical conditioning tasks. We found that each variable required to compute RPE, including actual and predicted reward, was distributed in input neurons in multiple brain areas. Further, many input neurons across brain areas signaled combinations of these variables. These results demonstrate that even simple arithmetic computations such as RPE are not localized in specific brain areas but, rather, distributed across multiple nodes in a brain-wide network. Our systematic method to examine both activity and connectivity revealed unexpected redundancy for a simple computation in the brain.

  18. Does Input Quality Drive Measured Differences in Firm Productivity?

    DEFF Research Database (Denmark)

    Fox, Jeremy T.; Smeets, Valerie Anne Rolande

    Firms in the same industry can differ in measured productivity by multiples of 3. Griliches (1957) suggests one explanation: the quality of inputs differs across firms. We add labor market history variables such as experience and firm and industry tenure, as well as general human capital measures...

  19. Rational Expansion for Nonlinear Input-Output Maps

    OpenAIRE

    1988-01-01

    This paper introduces a Rational Expansion for Nonlinear Input-Output MAPS. The method is new and is based on the rational expansion of functions of several complex variables. If truncated, this series reduces to a ratio of truncated Volterra series, A "feedback form" will be presented.

  20. Sensitivity of Monte Carlo simulations to input distributions

    Energy Technology Data Exchange (ETDEWEB)

    RamoRao, B. S.; Srikanta Mishra, S.; McNeish, J.; Andrews, R. W.

    2001-07-01

    The sensitivity of the results of a Monte Carlo simulation to the shapes and moments of the probability distributions of the input variables is studied. An economical computational scheme is presented as an alternative to the replicate Monte Carlo simulations and is explained with an illustrative example. (Author) 4 refs.

  1. Ground motion input in seismic evaluation studies

    Energy Technology Data Exchange (ETDEWEB)

    Sewell, R.T.; Wu, S.C.

    1996-07-01

    This report documents research pertaining to conservatism and variability in seismic risk estimates. Specifically, it examines whether or not artificial motions produce unrealistic evaluation demands, i.e., demands significantly inconsistent with those expected from real earthquake motions. To study these issues, two types of artificial motions are considered: (a) motions with smooth response spectra, and (b) motions with realistic variations in spectral amplitude across vibration frequency. For both types of artificial motion, time histories are generated to match target spectral shapes. For comparison, empirical motions representative of those that might result from strong earthquakes in the Eastern U.S. are also considered. The study findings suggest that artificial motions resulting from typical simulation approaches (aimed at matching a given target spectrum) are generally adequate and appropriate in representing the peak-response demands that may be induced in linear structures and equipment responding to real earthquake motions. Also, given similar input Fourier energies at high-frequencies, levels of input Fourier energy at low frequencies observed for artificial motions are substantially similar to those levels noted in real earthquake motions. In addition, the study reveals specific problems resulting from the application of Western U.S. type motions for seismic evaluation of Eastern U.S. nuclear power plants.

  2. Stochastic transitions into silence cause noise correlations in cortical circuits.

    Science.gov (United States)

    Mochol, Gabriela; Hermoso-Mendizabal, Ainhoa; Sakata, Shuzo; Harris, Kenneth D; de la Rocha, Jaime

    2015-03-17

    The spiking activity of cortical neurons is highly variable. This variability is generally correlated among nearby neurons, an effect commonly interpreted to reflect the coactivation of neurons due to anatomically shared inputs. Recent findings, however, indicate that correlations can be dynamically modulated, suggesting that the underlying mechanisms are not well understood. Here, we investigate the hypothesis that correlations are dominated by neuronal coinactivation: the occurrence of brief silent periods during which all neurons in the local network stop firing. We recorded spiking activity from large populations of neurons in the auditory cortex of anesthetized rats across different brain states. During spontaneous activity, the reduction of correlation accompanying brain state desynchronization was largely explained by a decrease in the density of the silent periods. The presentation of a stimulus caused an initial drop of correlations followed by a rebound, a time course that was mimicked by the instantaneous silence density. We built a rate network model with fluctuation-driven transitions between a silent and an active attractor and assumed that neurons fired Poisson spike trains with a rate following the model dynamics. Variations of the network external input altered the transition rate into the silent attractor and reproduced the relation between correlation and silence density found in the data, both in spontaneous and evoked conditions. This suggests that the observed changes in correlation, occurring gradually with brain state variations or abruptly with sensory stimulation, are due to changes in the likeliness of the microcircuit to transiently cease firing.

  3. Correlation between heart rate variability and brain natriuretic peptide in patients with persistent atrial fibrillation%持续性心房颤动患者心率变异性与脑钠尿肽的关系

    Institute of Scientific and Technical Information of China (English)

    李宏松; 石来新; 卢英民; 韦彩雯; 宋蕾; 李志华; 蔡振东

    2012-01-01

    目的:探讨持续性心房颤动患者心率变异性与脑钠尿肽(BNP)的相关性.方法:入选45例持续性心房颤动患者,20例正常对照组.行24小时动态心电图检查,检测心率变异性时域指标,并行BNP测定,再分析以上两者的相关性.结果:持续性房颤患者与对照组比较,心率增快,心率变异性时域指标SDNN、RMSSD、PNN50显著增加(P<0.01);平均RR间期(RINNT)实测值与BNP呈负相关;以平均心率矫正后的有关心率变异时域指标RMSS-DDdiff和PNN50Ddiff与BNP呈正相关.结论:持续性心房颤动患者心率变异性时域参数增加,BNP受心率和心率变异性改变的影响.%AIM: To investigate the correlation between heart rate variability and brain natriuretic peptide (BNP) in patients with persistent atrial fibrillation (AF). METHODS: Forty-five patients with persistent AF were placed into one group and 20 patients without persistent AF were placed in the normal control group. Twenty-four hour ECG was monitored for the time domain indexes of heart rate variability, and plasma BNP concentration was tested. Correlation between the time domain indexes and plasma BNP concentration was analyzed. RESULTS: In patients with persistent AF, the heart rate increased and heart rate variability time domain indexes (SDNN, RMSSD and PNN50) increased significantly (P < 0. 01). The actual RINNT was negatively correlated with plasma BNP concentration. After correction with the average heart rate, heart rate variability time domain indexes (RMSSDDdiff and PNN50Ddiff) were positively correlated with BNP concentration. CONCLUSION: In patients with persistent AF, the time domain parameters of heart rate variability increase and plasma BNP concentration is affected by the heart rate and the changes in heart rate variability.

  4. Estimates of Intraclass Correlation for Variables Related to Behavioral HIV/STD Prevention in a Predominantly African American and Hispanic Sample of Young Women

    Science.gov (United States)

    Pals, Sherri L.; Beaty, Brenda L.; Posner, Samuel F.; Bull, Sheana S.

    2009-01-01

    Studies designed to evaluate HIV and STD prevention interventions often involve random assignment of groups such as neighborhoods or communities to study conditions (e.g., to intervention or control). Investigators who design group-randomized trials (GRTs) must take the expected intraclass correlation coefficient (ICC) into account in sample size…

  5. Symptom-correlated brain regions in young adults with combined-type ADHD: their organization, variability, and relation to behavioral performance.

    Science.gov (United States)

    Depue, Brendan E; Burgess, Gregory C; Willcutt, Erik G; Bidwell, L Cinnamon; Ruzic, Luka; Banich, Marie T

    2010-05-30

    Attention Deficit Hyperactivity Disorder (ADHD) is a widely diagnosed psychiatric disorder of childhood that may continue to manifest itself during adulthood. Across adults and children, inattention appears to be the most developmentally stable symptomatology of ADHD. To determine the neural systems that may be linked to such symptoms, the association between brain activation in a group of young adults in the face of an attentional challenge (the Stroop task) and inattentive symptoms was examined with functional magnetic resonance imaging. The results implicated a broad array of brain regions that are linked to behaviors compromised in ADHD, including executive function/cognitive control (prefrontal cortex, dorsal striatum), reward and motivational circuitry (ventral striatum), and stimulus representation and timing (posterior cortex and cerebellum). Also implicating these regions as being important for the manifestation of ADHD symptoms, the variability in the size of the BOLD signal across individuals was significantly higher for the ADHD group than for the control group, and variability across the time series in individuals with ADHD was linked to symptom severity and behavioral performance. The results suggest that a diverse set of brain structures is linked to ADHD symptoms and that the variability of activation within these regions may contribute to compromised attentional control. Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.

  6. A new method for reliability sensitivity analysis with correlative normal variables%正态变量相关情况下可靠性灵敏度分析的新方法

    Institute of Scientific and Technical Information of China (English)

    何红妮; 吕震宙

    2011-01-01

    基于独立正态变量情况下可靠性灵敏度分析的线抽样法,提出了一种求解正态相关变量情况下可靠性灵敏度的新方法。在所提方法中,首先将正态相关变量等效变换为正态独立变量,然后利用线抽样方法独立完成等效独立变量情况下失效概率对独立变量的所有分布参数的灵敏度分析,最后依据等效变换前后变量分布参数之间的解析关系和复合函数求导公式,求得失效概率对相关变量所有分布参数的可靠性灵敏度。为了解所提方法的收敛性和精度,文中对所提方法进行了方差分析。算例结果表明,对于线性极限状态情况,所提方法经过一次线抽样即可得到可靠性灵敏度的精确解,而对于非线性极限状态情况,所提方法可以高效求得高精度的近似解。算例结果还表明,变量的相关性会引起失效概率对变量标准差灵敏度正、负符号的改变,这对于工程可靠性设计是非常有意义的。%Based on line sampling for reliability sensitivity in case of independent normal variables, a new reliability sensitivity analysis method is presented for the structure with correlative normal variables. In this method, the correlative normal variables are firstly transformed into independent normal variables e-quivalently. Then, the line sampling algorithm is employed to complete the reliability sensitivity of failure probability with respect to all distribution parameters in the space of equivalent independent variables. At last, by use of the distribution parameters relationship between the correlative normal variables and the independent normal variables, the reliability sensitivity of the failure probability with respect to all distribution parameters in the space of the correlative normal variables can be obtained by derivative formula of compound function. In order to investigate convergence and precision of the method, the variance and the variation

  7. Correlation of thermophoretically-modified small particle diffusional deposition rates in forced convection systems with variable properties, transpiration cooling and/or viscous dissipation

    Science.gov (United States)

    Gokoglu, S. A.; Rosner, D. E.

    1984-01-01

    A cooled object (heat exchanger tube or turbine blade) is considered to be immersed in a hot fluid stream containing trace amounts of suspended vapors and/or small particles. Numerical prediction calculations were done for self-similar laminar boundary layers and law-of-the-wall turbulent boundary layers. Correlations are presented for the effect of thermophoresis in the absence of transpiration cooling and viscous dissipation; the effect of real suction and blowing in the absence of thermophoresis; the effect of viscous dissipation on thermophoresis in the absence of transpiration cooling; and the combined effect of viscous dissipation and transpiration cooling on thermophoresis. The final correlation, St/St-sub-zero, is insensitive to particle properties, Euler number, and local mainstream temperature.

  8. Examination of the Two Models of Subjective Well-Being and Correlations between Satisfaction with Life, Demographic Variables and Personality Traits

    Directory of Open Access Journals (Sweden)

    Ivana Lučev

    2010-12-01

    Full Text Available The goal of this study was to further the understanding of complex processes that are the base for feelings and satisfaction judgments by examining two models of subjective well-being. 1048 participants rated satisfaction with life and filled out IPIP-50 questionnaire that measures personality traits of the Big five model and demographic data questionnaire. Satisfaction with life in general was statistically significantly positively correlated with satisfaction of relationships with other people, satisfaction with health as well as with specific aspects of these domains. As was expected according to judgment model, correlations were higher for global domains than for specific aspects of satisfaction except for satisfaction with mood. Hypothesis of general positivity model and judgment model were tested in a series of hierarchical regression analyses. General life satisfaction explained variance of both global domains above and beyond satisfaction with corresponding specific domains. Contribution of global life satisfaction was significant even after effect of big five personality traits was controlled. Personality traits of the Big five model were statistically significantly associated with general life satisfaction. Correlation coefficients were -0.41 for Neuroticism, 0.30 for Extraversion, 0.14 for Agreeableness, 0.13 for Conscientiousness and 0.22 for Intellect. Age, education and being in a relationship were positively correlated with general life satisfaction. In this connection younger, better educated persons and those being in relationship were more satisfied with life in general. Women had higher levels of satisfaction for relationship with parents, while men had higher levels of satisfaction with partner, mobility, energy level, immunity and absence of pain.

  9. Levels of Inflammatory Cytokines in Type 2 Diabetes Patients with Different Urinary Albumin Excretion Rates and Their Correlation with Clinical Variables

    Directory of Open Access Journals (Sweden)

    Fen-qin Chen

    2013-01-01

    Full Text Available Although the pathogenetic mechanism of DN has not been elucidated, an inflammatory mechanism has been suggested as a potential contributor. This study was designed to explore the relationship between low-grade inflammation and renal microangiopathy in T2DM. A total of 261 diabetic subjects were divided into three groups according to UAE: a normal albuminuria group, a microalbuminuria group, and a macroalbuminuria group. A control group was also chosen. Levels of hs-CRP, TNF-α, uMCP-1, SAA, SCr, BUN, serum lipid, blood pressure, and HbA1c were measured in all subjects. Compared with the normal controls, levels of hs-CRP, TNF-α, uMCP-1, and SAA in T2DM patients were significantly higher. They were also elevated in the normal albuminuria group, P<0.05. Compared with the normal albuminuria group, levels of these inflammatory cytokines were significantly higher in the microalbuminuria and macroalbuminuria group, P<0.01. The macroalbuminuria group also showed higher levels than the microalbuminuria group, P<0.01. Also they were positively correlated with UAE, SBP, DBP, LDL-C, and TC. We noted no significance correlated with course, TG, or HDL-C. Only TNF-α; was positively correlated with HbA1c. This study revealed the importance of these inflammatory cytokines in DN pathogenesis. Further studies are needed to fully establish the potential of these cytokines as additional biomarkers for the development of DN.

  10. Choice of input fields in stochastic finite elements

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager; Tarp-Johansen, Niels Jacob

    1999-01-01

    , the flexibility field, as the input to the stochastic finite element model. To answer this question the focus should be on the error of the output of the mechanical model rather than on the input field itself when discretizing the held through replacing it by a field defined in terms of a finite number of random...... variables. Several reported discretization methods define these random variables as integrals of the product of the held and some suitable weight functions. In particular, the weight functions can be Dirac delta functions whereby the random variables become the field values at a finite set of given points....... The replacement field is often defined as the linear regression of the original field on the considered vector of the weighted integrals of the field. For example, this holds for discretizations obtained by truncation of the Karhunen-Loeve expansion of the field, but only approximately so for truncations...

  11. Choice of input fields in stochastic finite elements

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager; Tarp-Johansen, Niels Jacob

    1996-01-01

    , the flexibility field, as the input to the stochastic finite element model. To answer this question the focus should be on the error of the output of the mechanical model rather than on the input field itself when discretizing the field through replacing it by a field defined in terms of a finite number of random...... variables. Several reported discretization methods define these random variables as integrals of the product of the field and some suitable weight functions. In particular, the weight functions can be Dirac delta functions whereby the random variables become the field values at a finite set of given points....... The replacement field is often defined as the linear regression of the original field on the considered vector of the weighted integrals of the field. For example, this holds for discretizations obtained by truncation of the Karhunen-Loeve expansion of the field, but only approximately so for truncations...

  12. Geographical variability in the likelihood of bloodstream infections due to gram-negative bacteria: correlation with proximity to the equator and health care expenditure.

    Science.gov (United States)

    Fisman, David; Patrozou, Eleni; Carmeli, Yehuda; Perencevich, Eli; Tuite, Ashleigh R; Mermel, Leonard A

    2014-01-01

    Infections due to Gram-negative bacteria exhibit seasonal trends, with peak infection rates during warmer months. We hypothesized that the likelihood of a bloodstream infection due to Gram-negative bacteria increases with proximity to the equator. We tested this hypothesis and identified geographical, climatic and social factors associated with this variability. We established a network of 23 international centers in 22 cities. De-identified results of positive blood cultures from 2007-2011 and data sources for geographic, climatic and socioeconomic factors were assembled for each center. Patients at the 23 centers with positive blood cultures. Due to variability in the availability of total culture volumes across sites, our primary outcome measure was the fraction of positive blood cultures that yielded Gram-negative bacteria; sources of variability in this outcome measure were explored using meta-regression techniques. The mean fraction of bacteremia associated with Gram-negative bacteria was 48.4% (range 26.4% to 61.8%). Although not all sites displayed significant seasonality, the overall P-value for seasonal oscillation was significant (Pnegative bacteria. In multivariable models, only percent of gross domestic product spent on healthcare and distance from the equator (ie. latitude squared) were significantly associated with the fraction of bacteremia due to Gram-negative bacteria. The likelihood of bacteremia due to Gram-negative bacteria varies markedly between cities, in a manner that appears to have both geographic (latitude) and socioeconomic (proportion gross domestic product devoted to health spending) determinants. Thus, the optimal approach to initial management of suspected bacteremia may be geographically specific. The rapid emergence of highly antibiotic-resistant Gram-negative pathogens may have geographically specific impacts.

  13. Lyme Disease Emergence in Virginia: An Examination of the Demographic and Environmental Variables Correlated to the Spatial Pattern of Disease Incidence

    OpenAIRE

    Dymond, Sara Elizabeth

    2013-01-01

    Since its initial identification in 1975, Lyme disease has become a public health concern in the U.S.  Increased concern is sparked by the rapid rate at which the disease is emerging into new areas.  One area of disease emergence is the state of Virginia which has been experiencing exponentially increasing rates of the disease.  This research studies Virginia\\'s landscape-level habitats to explore demographic and environmental variables related to the spread of Lyme disease. The land cover da...

  14. Weight-correction of carbon dioxide diffusion coefficient (DCO2 ) reduces its inter-individual variability and improves its correlation with blood carbon dioxide levels in neonates receiving high-frequency oscillatory ventilation.

    Science.gov (United States)

    Belteki, Gusztav; Lin, Benjamin; Morley, Colin J

    2017-10-01

    Carbon-dioxide elimination during high-frequency oscillatory ventilation (HFOV) is thought to be proportional to the carbon dioxide diffusion coefficient (DCO2 ) which is calculated as frequency x (tidal volume)(2) . DCO2 can be used to as an indicator of CO2 elimination but values obtained in different patients cannot be directly compared. To analyze the relationship between DCO2 , the weight-corrected DCO2 (DCO2 corr) and blood gas PCO2 values obtained from infants receiving HFOV. DCO2 data were obtained from 14 infants at 1/s sampling rate and the mean DCO2 was determined over 10 min periods preceding the time of the blood gas. DCO2 corr was calculated by dividing the DCO2 by the square of the body weight in kg. Weight-correction significantly reduced the inter-individual variability of DCO2 . When data from all the babies were combined, standard DCO2 showed no correlation with PCO2 but DCO2 corr showed a weak but statistically significant inverse correlation. The correlation was better when the endotracheal leak was 50 mL(2) /sec/kg(2) or VThf > 2.5 mL/kg was rarely needed to avoid hypercapnia. Weight-correction of DCO2 values improved its comparability between patients. Weight-corrected DCO2 correlated better with PCO2 than uncorrected DCO2 but the correlation was weak. © 2017 Wiley Periodicals, Inc.

  15. Optimal Input Design for Aircraft Parameter Estimation using Dynamic Programming Principles

    Science.gov (United States)

    Morelli, Eugene A.; Klein, Vladislav

    1990-01-01

    A new technique was developed for designing optimal flight test inputs for aircraft parameter estimation experiments. The principles of dynamic programming were used for the design in the time domain. This approach made it possible to include realistic practical constraints on the input and output variables. A description of the new approach is presented, followed by an example for a multiple input linear model describing the lateral dynamics of a fighter aircraft. The optimal input designs produced by the new technique demonstrated improved quality and expanded capability relative to the conventional multiple input design method.

  16. Conditions of Technical Stability on Non-Stationary Processes of Automatic Control of Variable Structure with Correlative Forming and Filtering Systems of Control Signals

    Directory of Open Access Journals (Sweden)

    Matviychuk K.S.

    2012-06-01

    Full Text Available The conditions of technical stability by measure of the dynamical states of the non-stationary control systems with variable structure are investigated in presence of filtration process of the control signals. The suitable systems of the differential equations have the changing coefficients, which are altering in time and by jumplike together with jumplike changing of the control function of the process and with simultaneous jumplike changing at the direction of the suitable phase velocity vector of the process. The criteria of technical stability by measure on finite and infinite intervals of time, asymptotical technical stability by measure, and also the criterion of the technical instability by measure of given, inwardly dependent on quality of filtering of control signals of non-stationary dynamical systems with variable structure are determiner under base of the differential inequalities method at combination with properties of the class of the absolutely positive functions, for all feasible initial disturbances from the pre-assigned by measure set of initial states of the process.

  17. Variability in the range of inter-anterior superior iliac spine distance and its correlation with femoral head centre. A prospective computed tomography study of 200 adults

    Energy Technology Data Exchange (ETDEWEB)

    Mullaji, Arun [Breach Candy Hospital, Department of Orthopaedic Surgery, Mumbai (India); Arthritis Clinic, Mumbai (India); Shetty, Gautam M.; Kanna, Raj; Sharma, Amit [Breach Candy Hospital, Department of Orthopaedic Surgery, Mumbai (India)

    2010-04-15

    The anterior superior iliac spine (ASIS) is commonly used to estimate the centre of the femoral head and assess limb alignment during surgical procedures. This study aimed to determine the range of inter-anterior superior iliac spine distances (IADs) and inter-femoral head centre distances (IFDs) among individuals and ascertain whether there is correlation between the IFD and the IAD. We also sought to determine whether gender, height and body mass index (BMI) had any influence on IAD and IFD. We prospectively measured IAD and IFD in 200 adults, using transverse computed tomography (CT) scans done for medical causes. We also calculated the distance between the pelvic midline and the centre of the femoral head (XY distance) from the measured IFD. The influence of gender, height and body-mass index on IAD and IFD, and the correlation of IAD with IFD, were also studied. The overall mean IAD, IFD and XY distances were 22.7 {+-} 1.6 cm, 16.0 {+-} 0.8 cm and 8.0 {+-} 0.4 cm, respectively. There was wide variation within the IAD range with 50% (100/200) of the subjects having their IAD within {+-}10 mm of the mean compared to 75.5% (151/200) of the subjects with IFD within {+-}10 mm of the mean. The probability that the mean XY distance would fall within 10 mm of the true femoral head centre in all subjects was 100%. The gender difference in IAD and IFD was statistically significant (P = 0.03 and P < 0.001, respectively), height and BMI had no influence, and the correlation of IAD with IFD was weak (0.35). Although the range of IADs showed wide variation among subjects, this study clearly demonstrated the narrow range of the XY distance and IFD in the study population and provides a useful and accurate basis for a new method to determine the femoral head centre clinically and intraoperatively. (orig.)

  18. MOnthly TEmperature DAtabase of Spain 1951-2010: MOTEDAS (2): The Correlation Decay Distance (CDD) and the spatial variability of maximum and minimum monthly temperature in Spain during (1981-2010).

    Science.gov (United States)

    Cortesi, Nicola; Peña-Angulo, Dhais; Simolo, Claudia; Stepanek, Peter; Brunetti, Michele; Gonzalez-Hidalgo, José Carlos

    2014-05-01

    One of the key point in the develop of the MOTEDAS dataset (see Poster 1 MOTEDAS) in the framework of the HIDROCAES Project (Impactos Hidrológicos del Calentamiento Global en España, Spanish Ministery of Research CGL2011-27574-C02-01) is the reference series for which no generalized metadata exist. In this poster we present an analysis of spatial variability of monthly minimum and maximum temperatures in the conterminous land of Spain (Iberian Peninsula, IP), by using the Correlation Decay Distance function (CDD), with the aim of evaluating, at sub-regional level, the optimal threshold distance between neighbouring stations for producing the set of reference series used in the quality control (see MOTEDAS Poster 1) and the reconstruction (see MOREDAS Poster 3). The CDD analysis for Tmax and Tmin was performed calculating a correlation matrix at monthly scale between 1981-2010 among monthly mean values of maximum (Tmax) and minimum (Tmin) temperature series (with at least 90% of data), free of anomalous data and homogenized (see MOTEDAS Poster 1), obtained from AEMEt archives (National Spanish Meteorological Agency). Monthly anomalies (difference between data and mean 1981-2010) were used to prevent the dominant effect of annual cycle in the CDD annual estimation. For each station, and time scale, the common variance r2 (using the square of Pearson's correlation coefficient) was calculated between all neighbouring temperature series and the relation between r2 and distance was modelled according to the following equation (1): Log (r2ij) = b*°dij (1) being Log(rij2) the common variance between target (i) and neighbouring series (j), dij the distance between them and b the slope of the ordinary least-squares linear regression model applied taking into account only the surrounding stations within a starting radius of 50 km and with a minimum of 5 stations required. Finally, monthly, seasonal and annual CDD values were interpolated using the Ordinary Kriging with a

  19. Astronaut Preflight Cardiovascular Variables Associated with Vascular Compliance are Highly Correlated with Post-Flight Eye Outcome Measures in the Visual Impairment Intracranial Pressure (VIIP) Syndrome Following Long Duration Spaceflight

    Science.gov (United States)

    Otto, Christian; Ploutz-Snyder, R.

    2015-01-01

    correlation between the eye outcomes and the twelve astronaut cardiovascular variables available for all 31 subjects. Results: A highly significant canonical correlation was observed among the canonical solutions (p F = 0.00001). Overall, female astronauts demonstrated a significantly healthier cardiovascular status. Individually, the female astronauts had significantly healthier profiles on seven of twelve cardiovascular variables than the men (p values ranging from <0.0001 to <0.05). Male astronauts did not demonstrate significantly healthier values on any of the twelve cardiovascular variables measured

  20. Assessing positive mental health in people with chronic physical health problems: correlations with socio-demographic variables and physical health status.

    Science.gov (United States)

    Lluch-Canut, Teresa; Puig-Llobet, Montserrat; Sánchez-Ortega, Aurelia; Roldán-Merino, Juan; Ferré-Grau, Carmen

    2013-10-05

    A holistic perspective on health implies giving careful consideration to the relationship between physical and mental health. In this regard the present study sought to determine the level of Positive Mental Health (PMH) among people with chronic physical health problems, and to examine the relationship between the observed levels of PMH and both physical health status and socio-demographic variables. The study was based on the Multifactor Model of Positive Mental Health (Lluch, 1999), which comprises six factors: Personal Satisfaction (F1), Prosocial Attitude (F2), Self-control (F3), Autonomy (F4), Problem-solving and Self-actualization (F5), and Interpersonal Relationship Skills (F6). The sample comprised 259 adults with chronic physical health problems who were recruited through a primary care center in the province of Barcelona (Spain). Positive mental health was assessed by means of the Positive Mental Health Questionnaire (Lluch, 1999). Levels of PMH differed, either on the global scale or on specific factors, in relation to the following variables: age: global PMH scores decreased with age (r=-0.129; p=0.038); b) gender: men scored higher on F1 (t=2.203; p=0.028) and F4 (t=3.182; p=0.002), while women scored higher on F2 (t -3.086; p=0.002) and F6 (t=-2.744; p=0.007); c) number of health conditions: the fewer the number of health problems the higher the PMH score on F5 (r=-0.146; p=0.019); d) daily medication: polymedication patients had lower PMH scores, both globally and on various factors; e) use of analgesics: occasional use of painkillers was associated with higher PMH scores on F1 (t=-2.811; p=0.006). There were no significant differences in global PMH scores according to the type of chronic health condition. The only significant difference in the analysis by factors was that patients with hypertension obtained lower PMH scores on the factor Autonomy (t=2.165; p=0.032). Most people with chronic physical health problems have medium or high levels of PMH

  1. Variability in biofilm formation correlates with hydrophobicity and quorum sensing among Vibrio parahaemolyticus isolates from food contact surfaces and the distribution of the genes involved in biofilm formation.

    Science.gov (United States)

    Mizan, Md Furkanur Rahaman; Jahid, Iqbal Kabir; Kim, Minhui; Lee, Ki-Hoon; Kim, Tae Jo; Ha, Sang-Do

    2016-01-01

    Vibrio parahaemolyticus is one of the leading foodborne pathogens causing seafood contamination. Here, 22 V. parahaemolyticus strains were analyzed for biofilm formation to determine whether there is a correlation between biofilm formation and quorum sensing (QS), swimming motility, or hydrophobicity. The results indicate that the biofilm formation ability of V. parahaemolyticus is positively correlated with cell surface hydrophobicity, autoinducer (AI-2) production, and protease activity. Field emission scanning electron microscopy (FESEM) showed that strong-biofilm-forming strains established thick 3-D structures, whereas poor-biofilm-forming strains produced thin inconsistent biofilms. In addition, the distribution of the genes encoding pandemic clone factors, type VI secretion systems (T6SS), biofilm functions, and the type I pilus in the V. parahaemolyticus seafood isolates were examined. Biofilm-associated genes were present in almost all the strains, irrespective of other phenotypes. These results indicate that biofilm formation on/in seafood may constitute a major factor in the dissemination of V. parahaemolyticus and the ensuing diseases.

  2. Correlações genotípicas, fenotípicas e ambientais entre caracteres de mamoneira Genotypic, phenotypic and environmental correlations among castor bean variables

    Directory of Open Access Journals (Sweden)

    Helen Cristina de Arruda Rodrigues

    2010-12-01

    Full Text Available Um dos grandes desafios atuais da pesquisa agrícola é a produção de cultivares melhoradas de mamoneira, com estabilidade genética, alta qualidade e potencial produtivo. Objetivou-se, no presente trabalho, estimar as correlações genotípica, fenotípica e de ambiente entre caracteres de mamona para facilitar a caracterização dos acessos. Foram avaliados em Lavras, MG, no delineamento de blocos casualizados com três repetições, quinze acessos de mamona. Os caracteres avaliados foram altura da planta, altura do caule, número de internódios, diâmetro do caule, número de cachos, estande final e peso de 100 sementes. Observou-se que houve correlação fenotípica positiva do número de internódios e altura do caule, altura do caule e altura da planta, altura da planta e diâmetro do caule e por fim entre diâmetro do caule e peso de 100 sementes. Houve também correlação ambiental positiva entre as correlações altura de caule e altura de planta, altura de planta e diâmetro do caule, altura da planta e estande final e diâmetro do caule e número de cachos, concluindo que as correlações estimadas possibilitaram conhecer as associações entre os caracteres, fornecendo importantes informações para o estabelecimento de um plano de melhoramento genético da mamona, a partir dos acessos avaliados.One of the great current challenges of agricultural research is the production of improved castor bean cultivars, with genetic stability, high quality and high yielding potential. The objective this work was to estimate genotypic, phenotypic and environmental correlations among traits of the castor bean plant to make the characterization of the accessions easy. They were evaluated in Lavras, MG, Brazil, in a randomized block design with three replicates, fifteen castor bean accessions. The traits evaluated were: plant height, stem height, number of nodes, stem diameter, final number of clusters, stand and 100-seed weight. It was observed

  3. The Correlating Control Model of Water Hammer Caused by Variable Frequency Flow Regulation%变频调速所致水击的关联控制模型研究

    Institute of Scientific and Technical Information of China (English)

    张玲艳; 邱水才; 卢齐英; 吴馨芳

    2011-01-01

    The application of highly-efficient energy-saving variable frequency flow regulation technique is becoming more and more widespread, and the phenomenon of water hammer caused by variable frequency flow regulation has become the key technical problem of its application. Based on the characteristics of water hammer caused by variable frequency flow regulation, the correlating control model of the rheological properties parameters which avoided water hammer caused by variable frequency flow regulation was es tablished. It lays theoretical foundation for water hammer pressure precise control.%高效节能的变频流量控制技术的应用日趋广泛,而由变频流量控制所致水击现象成为该技术应用的关键技术问题.针对变频流量控制所致水击过程的特点,建立了避免变频流量控制所致水击的流变性能参数的关联控制模型,为水击压力精确控制奠定了理论基础.

  4. Effects of input uncertainty on cross-scale crop modeling

    Science.gov (United States)

    Waha, Katharina; Huth, Neil; Carberry, Peter

    2014-05-01

    The quality of data on climate, soils and agricultural management in the tropics is in general low or data is scarce leading to uncertainty in process-based modeling of cropping systems. Process-based crop models are common tools for simulating crop yields and crop production in climate change impact studies, studies on mitigation and adaptation options or food security studies. Crop modelers are concerned about input data accuracy as this, together with an adequate representation of plant physiology processes and choice of model parameters, are the key factors for a reliable simulation. For example, assuming an error in measurements of air temperature, radiation and precipitation of ± 0.2°C, ± 2 % and ± 3 % respectively, Fodor & Kovacs (2005) estimate that this translates into an uncertainty of 5-7 % in yield and biomass simulations. In our study we seek to answer the following questions: (1) are there important uncertainties in the spatial variability of simulated crop yields on the grid-cell level displayed on maps, (2) are there important uncertainties in the temporal variability of simulated crop yields on the aggregated, national level displayed in time-series, and (3) how does the accuracy of different soil, climate and management information influence the simulated crop yields in two crop models designed for use at different spatial scales? The study will help to determine whether more detailed information improves the simulations and to advise model users on the uncertainty related to input data. We analyse the performance of the point-scale crop model APSIM (Keating et al., 2003) and the global scale crop model LPJmL (Bondeau et al., 2007) with different climate information (monthly and daily) and soil conditions (global soil map and African soil map) under different agricultural management (uniform and variable sowing dates) for the low-input maize-growing areas in Burkina Faso/West Africa. We test the models' response to different levels of input

  5. Developmental associations between short-term variability and long-term changes: Intraindividual correlation of positive and negative affect in daily life and cognitive aging.

    Science.gov (United States)

    Hülür, Gizem; Hoppmann, Christiane A; Ram, Nilam; Gerstorf, Denis

    2015-07-01

    Conceptual notions and empirical evidence suggest that the intraindividual correlation (iCorr) of positive affect (PA) and negative affect (NA) is a meaningful characteristic of affective functioning. PA and NA are typically negatively correlated within-person. Previous research has found that the iCorr of PA and NA is relatively stable over time within individuals, that it differs across individuals, and that a less negative iCorr is associated with better resilience and less vulnerability. However, little is known about how the iCorr of PA and NA relates to cognitive aging. This project examined how the association between PA and NA in everyday life is associated with long-term cognitive aging trajectories. To do so, we linked microlongitudinal data on PA and NA obtained on up to 33 occasions over 6 consecutive days with macrolongitudinal data on fluid and crystallized cognitive abilities obtained over 15 years from a subsample of Berlin Aging Study participants (N = 81, mean age at the microlongitudinal study = 81 years, range 73-98; 41% women). Over and above age, gender, education, overall levels of PA and NA, and number of health conditions, a less negative iCorr of PA and NA was associated with lower levels of cognitive ability and steeper cognitive declines, particularly for fluency and knowledge abilities. We discuss possible mechanisms for this finding and argue that a less negative iCorr of PA and NA may be indicative of deficits in emotional integration that are tied to changes in crystallized aspects of cognitive abilities. (c) 2015 APA, all rights reserved).

  6. A Correlation Study on Water Quality Variables in an Area of the Huaihe River Basin%淮河某流域水质指标相关性研究

    Institute of Scientific and Technical Information of China (English)

    王永梅; 肖中新

    2012-01-01

    根据淮河某流域近几年来的采样数据,运用Pearson相关系数和曲线估计的方法分析了水质指标间的相关性。结果表明,生化需氧量、化学需氧量、氨氮之间均存在显著的正相关关系,而溶解氧和其他各指标之间均存在显著负相关,并结合回归系数建立了估计方程,通过对判定系数R2和F分布检验的分析,表明曲线估计的方法更能准确表述水质指标间的相关性,也更加符合实际情况,具有一定的实用价值。%Correlations between water quality variables were analysed by using Pearson correlation coefficient and curve estimation method based on the observation data obtained in an area of the Huaihe River Basin in recent years. It has shown that there were significant positive correlations between biochemical oxygen demand, chemical oxygen demand, and ammonia nitrogen, whilst significant negative correlations between dissolved oxygen and other variables. Furthermore, estimating equations were established in combination with regression coefficients. An analysis on the adjusted coefficient of determination R2 and F-distribution test indicated that curve estimation method could represent the relationships between water quality parameters more accurately and could well accord with actual situation so as to be of certain practical values.

  7. Repositioning Recitation Input in College English Teaching

    Science.gov (United States)

    Xu, Qing

    2009-01-01

    This paper tries to discuss how recitation input helps overcome the negative influences on the basis of second language acquisition theory and confirms the important role that recitation input plays in improving college students' oral and written English.

  8. Evidence for Variable, Correlated X-ray and Optical/IR Extinction toward the Nearby, Pre-main Sequence Binary TWA 30

    CERN Document Server

    Principe, David A; Kastner, Joel H; Stelzer, Beate; Alcala, Juan

    2016-01-01

    We present contemporaneous XMM-Newton X-ray and ground-based optical/near-IR spectroscopic observations of the nearby ($D \\approx 42$ pc), low-mass (mid-M) binary system TWA 30A and 30B. The components of this wide (separation $\\sim$3400 AU) binary are notable for their nearly edge-on disk viewing geometries, high levels of variability, and evidence for collimated stellar outflows. We obtained XMM-Newton X-ray observations of TWA 30A and 30B in 2011 June and July, accompanied (respectively) by IRTF SpeX (near-IR) and VLT XSHOOTER (visible/near-IR) spectroscopy obtained within $\\sim$20 hours of the X-ray observations. TWA 30A was detected in both XMM-Newton observations at relatively faint intrinsic X-ray luminosities ($L_{X}$$\\sim$$8\\times10^{27}$ $erg$ $s^{-1}$) compared to stars of similar mass and age . The intrinsic (0.15-2.0 keV) X-ray luminosities measured in 2011 had decreased by a factor 20-100 relative to a 1990 (ROSAT) X-ray detection. TWA 30B was not detected, and we infer an upper limit of ($L_{X}...

  9. Correlation between heart rate variability and coronary heart disease%心率变异性与冠心病相关性研究

    Institute of Scientific and Technical Information of China (English)

    姜悦; 杜凤和; 郭一力

    2012-01-01

    Objective The heart rate variability (HRV) indicators of patients who had questionable angina symptoms and underwent CAG and AECG were collected and compared. Method Patients with unknown causes of chest pain were divided into CAD and non-CAD according to the CAG results. Results HRV indexes in CAD group were lower than non-CAD group,there were significantly differences among SDNN,RMSSD and PNN50 (P<0.05). Conclusion HRV is decreased in patients with coronary heart disease. The autonomic nerve of CAD patients is in dysfunction,maily the vagus nerves.%目的 探讨心率变异性(HRV)的临床意义.方法 选择以“胸痛待查”患者,行动态心电图(AECG)及冠状动脉造影(CAG)检查.按CAG结果分为CAD(冠心病)组与非CAD组.对比分析AECG所获得的心率变异性指标.结果 CAD组HRV各指标均不同程度低于非CAD组,其中两组间SDNN、rMSSD、pNN50差异有统计学意义(P<0.05).结论 冠心病患者心率变异性降低;冠心病患者心脏自主神经功能紊乱,以迷走神经紊乱为主.

  10. Inter- and intraobserver variability of MR arthrography in the detection and classification of superior labral anterior posterior (SLAP) lesions: evaluation in 78 cases with arthroscopic correlation

    Energy Technology Data Exchange (ETDEWEB)

    Holzapfel, Konstantin; Waldt, Simone; Bruegel, Melanie; Rummeny, Ernst J.; Woertler, Klaus [Technische Universitaet Muenchen, Department of Radiology, Klinikum rechts der Isar, Munich (Germany); Paul, Jochen; Imhoff, Andreas B. [Technische Universitaet Muenchen, Department of Sports Orthopedics, Klinikum rechts der Isar, Munich (Germany); Heinrich, Petra [Technische Universitaet Muenchen, Institute of Medical Statistics and Epidemiology, Klinikum rechts der Isar, Munich (Germany)

    2010-03-15

    The purpose of this study was to determine inter- and intraobserver variability of MR arthrography of the shoulder in the detection and classification of superior labral anterior posterior (SLAP) lesions. MR arthrograms of 78 patients who underwent MR arthrography before arthroscopy were retrospectively analysed by three blinded readers for the presence and type of SLAP lesions. MR arthrograms were reviewed twice by each reader with a time interval of 4 months between the two readings. Inter- and intraobserver agreement for detection and classification of SLAP lesions were calculated using {kappa} coefficients. Arthroscopy confirmed 48 SLAP lesions: type I (n = 4), type II (n = 37), type III (n = 3), type IV (n = 4). Sensitivity and specificity for detecting SLAP lesions with MR arthrography for each reader were 88.6%/93.3%, 90.9%/80.0% and 86.4%/76.7%. MR arthrographic and arthroscopic grading were concurrent for 72.7%, 68.2% and 70.5% of SLAP lesions for readers 1-3, respectively. Interobserver agreement was excellent ({kappa} = 0.82) for detection and substantial ({kappa} = 0.63) for classification of SLAP lesions. For each reader intraobserver agreement was excellent for detection ({kappa} = 0.93, {kappa} = 0.97, {kappa} = 0.97) and classification ({kappa} = 0.94, {kappa} = 0.84, {kappa} = 0.93) of SLAP lesions. MR arthrography allows reliable and accurate detection of SLAP lesions. In addition, SLAP lesions can be diagnosed and classified with substantial to excellent inter- and intraobserver agreement. (orig.)

  11. A Practical pedestrian approach to parsimonious regression with inaccurate inputs

    Directory of Open Access Journals (Sweden)

    Seppo Karrila

    2014-04-01

    Full Text Available A measurement result often dictates an interval containing the correct value. Interval data is also created by roundoff, truncation, and binning. We focus on such common interval uncertainty in data. Inaccuracy in model inputs is typically ignored on model fitting. We provide a practical approach for regression with inaccurate data: the mathematics is easy, and the linear programming formulations simple to use even in a spreadsheet. This self-contained elementary presentation introduces interval linear systems and requires only basic knowledge of algebra. Feature selection is automatic; but can be controlled to find only a few most relevant inputs; and joint feature selection is enabled for multiple modeled outputs. With more features than cases, a novel connection to compressed sensing emerges: robustness against interval errors-in-variables implies model parsimony, and the input inaccuracies determine the regularization term. A small numerical example highlights counterintuitive results and a dramatic difference to total least squares.

  12. Linearisation via input-output injection of time delay systems

    Science.gov (United States)

    García-Ramírez, Eduardo; Moog, Claude H.; Califano, Claudia; Alejandro Márquez-Martínez, Luis

    2016-06-01

    This paper deals with the problem of linearisation of systems with constant commensurable delays by input-output injection using algebraic control tools based on the theory of non-commutative rings. Solutions for the problem of linearisation free of delays, and with delays of an observable nonlinear time-delay systems are presented based on the analysis of the input-output equation. These results are achieved by means of constructive algorithms that use the nth derivative of the output expressed in terms of the state-space variables instead of the explicit computation of the input-output representation of the system. Necessary and sufficient conditions are established in both cases by means of an invertible change of coordinates.

  13. Facilitating agricultural input distribution in Uganda - Experiences ...

    African Journals Online (AJOL)

    Mo

    The input supply market however, suffered a setback as a result of the ... Ltd. redefined the approach emphasizing a demand driven input market by shifting ... Training of business entrepreneurs in business planning, ... The strategy to increase rural demand for agricultural inputs ..... During season 2004A, the basic fertilizers.

  14. Effects of Auditory Input in Individuation Tasks

    Science.gov (United States)

    Robinson, Christopher W.; Sloutsky, Vladimir M.

    2008-01-01

    Under many conditions auditory input interferes with visual processing, especially early in development. These interference effects are often more pronounced when the auditory input is unfamiliar than when the auditory input is familiar (e.g. human speech, pre-familiarized sounds, etc.). The current study extends this research by examining how…

  15. 7 CFR 3430.607 - Stakeholder input.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Stakeholder input. 3430.607 Section 3430.607 Agriculture Regulations of the Department of Agriculture (Continued) COOPERATIVE STATE RESEARCH, EDUCATION... § 3430.607 Stakeholder input. CSREES shall seek and obtain stakeholder input through a variety of...

  16. 7 CFR 3430.15 - Stakeholder input.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Stakeholder input. 3430.15 Section 3430.15... Stakeholder input. Section 103(c)(2) of the Agricultural Research, Extension, and Education Reform Act of 1998... RFAs for competitive programs. CSREES will provide instructions for submission of stakeholder input...

  17. 7 CFR 3430.907 - Stakeholder input.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Stakeholder input. 3430.907 Section 3430.907 Agriculture Regulations of the Department of Agriculture (Continued) COOPERATIVE STATE RESEARCH, EDUCATION... Program § 3430.907 Stakeholder input. CSREES shall seek and obtain stakeholder input through a variety...

  18. Interleukin-17A Gene Variability in Patients with Type 1 Diabetes Mellitus and Chronic Periodontitis: Its Correlation with IL-17 Levels and the Occurrence of Periodontopathic Bacteria.

    Science.gov (United States)

    Borilova Linhartova, Petra; Kastovsky, Jakub; Lucanova, Svetlana; Bartova, Jirina; Poskerova, Hana; Vokurka, Jan; Fassmann, Antonin; Kankova, Katerina; Izakovicova Holla, Lydie

    2016-01-01

    Interleukin-17 contributes to the pathogenesis of type 1 diabetes mellitus (T1DM) and chronic periodontitis (CP). We analyzed IL-17A -197A/G and IL-17F +7488C/T polymorphisms in T1DM and CP and determined their associations with IL-17 production and occurrence of periopathogens. Totally 154 controls, 125 T1DM, and 244 CP patients were genotyped using 5' nuclease TaqMan(®) assays. Bacterial colonization was investigated by a DNA-microarray kit. Production of IL-17 after in vitro stimulation of mononuclear cells by mitogens and bacteria was examined by the Luminex system. Although no differences in the allele/genotype frequencies between patients with CP and T1DM + CP were found, the IL-17A -197 A allele increased the risk of T1DM (P < 0.05). Levels of HbA1c were significantly elevated in carriers of the A allele in T1DM patients (P < 0.05). Production of IL-17 by mononuclear cells of CP patients (unstimulated/stimulated by Porphyromonas gingivalis) was associated with IL-17A A allele (P < 0.05). IL-17A polymorphism increased the number of Tannerella forsythia and Treponema denticola in patients with CP and T1DM + CP, respectively (P < 0.05). IL-17A gene variability may influence control of T1DM and the "red complex" bacteria occurrence in patients with CP and T1DM + CP. Our findings demonstrated the functional relevance of the IL-17A polymorphism with higher IL-17 secretion in individuals with A allele.

  19. Interleukin-17A Gene Variability in Patients with Type 1 Diabetes Mellitus and Chronic Periodontitis: Its Correlation with IL-17 Levels and the Occurrence of Periodontopathic Bacteria

    Directory of Open Access Journals (Sweden)

    Petra Borilova Linhartova

    2016-01-01

    Full Text Available Interleukin-17 contributes to the pathogenesis of type 1 diabetes mellitus (T1DM and chronic periodontitis (CP. We analyzed IL-17A −197A/G and IL-17F +7488C/T polymorphisms in T1DM and CP and determined their associations with IL-17 production and occurrence of periopathogens. Totally 154 controls, 125 T1DM, and 244 CP patients were genotyped using 5′ nuclease TaqMan® assays. Bacterial colonization was investigated by a DNA-microarray kit. Production of IL-17 after in vitro stimulation of mononuclear cells by mitogens and bacteria was examined by the Luminex system. Although no differences in the allele/genotype frequencies between patients with CP and T1DM + CP were found, the IL-17A −197 A allele increased the risk of T1DM (P<0.05. Levels of HbA1c were significantly elevated in carriers of the A allele in T1DM patients (P<0.05. Production of IL-17 by mononuclear cells of CP patients (unstimulated/stimulated by Porphyromonas gingivalis was associated with IL-17A A allele (P<0.05. IL-17A polymorphism increased the number of Tannerella forsythia and Treponema denticola in patients with CP and T1DM + CP, respectively (P<0.05. IL-17A gene variability may influence control of T1DM and the “red complex” bacteria occurrence in patients with CP and T1DM + CP. Our findings demonstrated the functional relevance of the IL-17A polymorphism with higher IL-17 secretion in individuals with A allele.

  20. Input calibration for negative originals

    Science.gov (United States)

    Tuijn, Chris

    1995-04-01

    One of the major challenges in the prepress environment consists of controlling the electronic color reproduction process such that a perfect match of any original can be realized. Whether this goal can be reached depends on many factors such as the dynamic range of the input device (scanner, camera), the color gamut of the output device (dye sublimation printer, ink-jet printer, offset), the color management software etc. The characterization of the color behavior of the peripheral devices is therefore very important. Photographs and positive transparents reflect the original scene pretty well; for negative originals, however, there is no obvious link to either the original scene or a particular print of the negative under consideration. In this paper, we establish a method to scan negatives and to convert the scanned data to a calibrated RGB space, which is known colorimetrically. This method is based on the reconstruction of the original exposure conditions (i.e., original scene) which generated the negative. Since the characteristics of negative film are quite diverse, a special calibration is required for each combination of scanner and film type.

  1. Genetic and epigenetic variability in the gene for IGFBP-3 (IGFBP3): correlation with serum IGFBP-3 levels and growth in short children born small for gestational age.

    Science.gov (United States)

    van der Kaay, D C M; Hendriks, A E J; Ester, W A; Leunissen, R W J; Willemsen, R H; de Kort, S W K; Paquette, J R; Hokken-Koelega, A C S; Deal, C L

    2009-06-01

    IGF-I and IGFBP-3 play a central role in fetal and postnatal growth and levels are low in short SGA children. The -202 A/C and -185 C/T SNPs are located near elements involved in directing IGFBP3 promoter activity and expression. Changes in promoter CpG methylation status affect transcription factor binding and transcriptional activation of IGFBP3 in vitro. To assess the relationship between IGFBP3 promoter SNPs, IGFBP-3 levels, spontaneous growth and growth response to GH treatment in short prepubertal SGA children. To assess promoter methylation status in a subgroup of short SGA subjects and controls. 292 Short prepubertal SGA children, 39 short young SGA adults and 85 young adults with normal stature. Short prepubertal SGA children received GH 1mg/m(2)/day. Fasting levels of IGF-I and IGFBP-3, baseline and delta height SDS. At baseline, IGFBP-3 levels were highest in SGA children with -202 AA genotype and lower in children with 1 or 2 copies of the C-allele (P<0.001). Children with C(-202)/C(-185) haplotype, compared to children with A(-202)/C(-185) haplotype, had lower IGFBP-3 levels (P=0.003) and were shorter (P=0.03). During GH treatment, children with C(-202)/C(-185) haplotype showed a significantly greater increase in IGFBP-3 SDS and in height SDS than children with A(-202)/C(-185) haplotype, resulting in similar IGFBP-3 levels and similar height SDS after 12 months of GH treatment. CpG methylation patterns showed a trend towards more methylation of CpGs involved in transcription factor binding in short young SGA adults compared to controls. Polymorphic variation in the IGFBP3 promoter region is correlated with IGFBP-3 levels, spontaneous growth and response to GH treatment in short SGA children.

  2. Optimization of precipitation inputs for SWAT modeling in mountainous catchment

    Science.gov (United States)

    Tuo, Ye; Chiogna, Gabriele; Disse, Markus

    2016-04-01

    Precipitation is often the most important input data in hydrological models when simulating streamflow in mountainous catchment. The Soil and Water Assessment Tool (SWAT), a widely used hydrological model, only makes use of data from one precipitation gauging station which is nearest to the centroid of each subcatchment, eventually corrected using the band elevation method. This leads in general to inaccurate subcatchment precipitation representation, which results in unreliable simulation results in mountainous catchment. To investigate the impact of the precipitation inputs and consider the high spatial and temporal variability of precipitation, we first interpolated 21 years (1990-2010) of daily measured data using the Inverse Distance Weighting (IDW) method. Averaged IDW daily values have been calculated at the subcatchment scale to be further supplied as optimized precipitation inputs for SWAT. Both datasets (Measured data and IDW data) are applied to three Alpine subcatchments of the Adige catchment (North-eastern Italy, 12100 km2) as precipitation inputs. Based on the calibration and validation results, model performances are evaluated according to the Nash Sutchliffe Efficiency (NSE) and Coefficient of Determination (R2). For all three subcatchments, the simulation results with IDW inputs are better than the original method which uses measured inputs from the nearest station. This suggests that IDW method could improve the model performance in Alpine catchments to some extent. By taking into account and weighting the distance between precipitation records, IDW supplies more accurate precipitation inputs for each individual Alpine subcatchment, which would as a whole lead to an improved description of the hydrological behavior of the entire Adige catchment.

  3. Turn customer input into innovation.

    Science.gov (United States)

    Ulwick, Anthony W

    2002-01-01

    It's difficult to find a company these days that doesn't strive to be customer-driven. Too bad, then, that most companies go about the process of listening to customers all wrong--so wrong, in fact, that they undermine innovation and, ultimately, the bottom line. What usually happens is this: Companies ask their customers what they want. Customers offer solutions in the form of products or services. Companies then deliver these tangibles, and customers just don't buy. The reason is simple--customers aren't expert or informed enough to come up with solutions. That's what your R&D team is for. Rather, customers should be asked only for outcomes--what they want a new product or service to do for them. The form the solutions take should be up to you, and you alone. Using Cordis Corporation as an example, this article describes, in fine detail, a series of effective steps for capturing, analyzing, and utilizing customer input. First come indepth interviews, in which a moderator works with customers to deconstruct a process or activity in order to unearth "desired outcomes." Addressing participants' comments one at a time, the moderator rephrases them to be both unambiguous and measurable. Once the interviews are complete, researchers then compile a comprehensive list of outcomes that participants rank in order of importance and degree to which they are satisfied by existing products. Finally, using a simple mathematical formula called the "opportunity calculation," researchers can learn the relative attractiveness of key opportunity areas. These data can be used to uncover opportunities for product development, to properly segment markets, and to conduct competitive analysis.

  4. Global sensitivity analysis approach for input selection and system identification purposes--a new framework for feedforward neural networks.

    Science.gov (United States)

    Fock, Eric

    2014-08-01

    A new algorithm for the selection of input variables of neural network is proposed. This new method, applied after the training stage, ranks the inputs according to their importance in the variance of the model output. The use of a global sensitivity analysis technique, extended Fourier amplitude sensitivity test, gives the total sensitivity index for each variable, which allows for the ranking and the removal of the less relevant inputs. Applied to some benchmarking problems in the field of features selection, the proposed approach shows good agreement in keeping the relevant variables. This new method is a useful tool for removing superfluous inputs and for system identification.

  5. Learning to represent visual input.

    Science.gov (United States)

    Hinton, Geoffrey E

    2010-01-12

    One of the central problems in computational neuroscience is to understand how the object-recognition pathway of the cortex learns a deep hierarchy of nonlinear feature detectors. Recent progress in machine learning shows that it is possible to learn deep hierarchies without requiring any labelled data. The feature detectors are learned one layer at a time and the goal of the learning procedure is to form a good generative model of images, not to predict the class of each image. The learning procedure only requires the pairwise correlations between the activations of neuron-like processing units in adjacent layers. The original version of the learning procedure is derived from a quadratic 'energy' function but it can be extended to allow third-order, multiplicative interactions in which neurons gate the pairwise interactions between other neurons. A technique for factoring the third-order interactions leads to a learning module that again has a simple learning rule based on pairwise correlations. This module looks remarkably like modules that have been proposed by both biologists trying to explain the responses of neurons and engineers trying to create systems that can recognize objects.

  6. Estimating latency from inhibitory input

    DEFF Research Database (Denmark)

    Levakova, Marie; Ditlevsen, Susanne; Lansky, Petr

    2014-01-01

    to the stimulus by an increase in the firing rate. We focus on the estimation of the response latency in the case of inhibitory stimuli. Models used in this paper represent two different descriptions of response latency. We consider either the latency to be constant across trials or to be a random variable......Stimulus response latency is the time period between the presentation of a stimulus and the occurrence of a change in the neural firing evoked by the stimulation. The response latency has been explored and estimation methods proposed mostly for excitatory stimuli, which means that the neuron reacts....... In the case of random latency, special attention is given to models with selective interaction. The aim is to propose methods for estimation of the latency or the parameters of its distribution. Parameters are estimated by four different methods: method of moments, maximum-likelihood method, a method...

  7. Signatures of synchrony in pairwise count correlations

    Directory of Open Access Journals (Sweden)

    Tatjana Tchumatchenko

    2010-04-01

    Full Text Available Concerted neural activity can reflect specific features of sensory stimuli or behavioral tasks. Correlation coefficients and count correlations are frequently used to measure correlations between neurons, design synthetic spike trains and build population models. But are correlation coefficients always a reliable measure of input correlations? Here, we consider a stochastic model for the generation of correlated spike sequences which replicate neuronal pairwise correlations in many important aspects. We investigate under which conditions the correlation coefficients reflect the degree of input synchrony and when they can be used to build population models. We find that correlation coefficients can be a poor indicator of input synchrony for some cases of input correlations. In particular, count correlations computed for large time bins can vanish despite the presence of input correlations. These findings suggest that network models or potential coding schemes of neural population activity need to incorporate temporal properties of correlated inputs and take into consideration the regimes of firing rates and correlation strengths to ensure that their building blocks are an unambiguous measures of synchrony.

  8. Spatial and temporal variability of sediment deposition on artificial-lawn traps in a floodplain of the River Elbe.

    Science.gov (United States)

    Baborowski, M; Büttner, O; Morgenstern, P; Krüger, F; Lobe, I; Rupp, H; Tümpling, W V

    2007-08-01

    Artificial-lawn mats were used as sediment traps in floodplains to measure sediment input and composition during flood events. To estimate the natural variability, 10 traps were installed during two flood waves at three different morphological units in a meander loop of the River Elbe. The geochemical composition of deposited and suspended matter was compared. The sediment input showed weak correlations with concentration and composition of river water. It also correlated poorly with flood duration and level as well as distance of trap position from the main river. This is due to the high variability of the inundation, different morphological conditions and the variability of sources. The composition of the deposits and the suspended matter in the river water was comparable. Hence, for the investigated river reach, the expected pollution of the floodplain sediments can be derived from the pollution of the suspended matter in the river during the flood wave.

  9. Input estimation from measured structural response

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, Dustin [Los Alamos National Laboratory; Cross, Elizabeth [Los Alamos National Laboratory; Silva, Ramon A [Los Alamos National Laboratory; Farrar, Charles R [Los Alamos National Laboratory; Bement, Matt [Los Alamos National Laboratory

    2009-01-01

    This report will focus on the estimation of unmeasured dynamic inputs to a structure given a numerical model of the structure and measured response acquired at discrete locations. While the estimation of inputs has not received as much attention historically as state estimation, there are many applications where an improved understanding of the immeasurable input to a structure is vital (e.g. validating temporally varying and spatially-varying load models for large structures such as buildings and ships). In this paper, the introduction contains a brief summary of previous input estimation studies. Next, an adjoint-based optimization method is used to estimate dynamic inputs to two experimental structures. The technique is evaluated in simulation and with experimental data both on a cantilever beam and on a three-story frame structure. The performance and limitations of the adjoint-based input estimation technique are discussed.

  10. Input Method "Five Strokes": Advantages and Problems

    Directory of Open Access Journals (Sweden)

    Mateja PETROVČIČ

    2014-03-01

    Since the Five Stroke input method is easily accessible, simple to master and is not pronunciation-based, we would expect that the students will use it to input unknown characters. The survey comprises students of Japanology and Sinology at Department of Asian and African Studies, takes in consideration the grade of the respondent and therefore his/her knowledge of characters. This paper also discusses the impact of typeface to the accuracy of the input.

  11. Nonlinear autoregressive neural networks with external inputs for forecasting of typhoon inundation level.

    Science.gov (United States)

    Ouyang, Huei-Tau

    2017-08-01

    Accurate inundation level forecasting during typhoon invasion is crucial for organizing response actions such as the evacuation of people from areas that could potentially flood. This paper explores the ability of nonlinear autoregressive neural networks with exogenous inputs (NARX) to predict inundation levels induced by typhoons. Two types of NARX architecture were employed: series-parallel (NARX-S) and parallel (NARX-P). Based on cross-correlation analysis of rainfall and water-level data from historical typhoon records, 10 NARX models (five of each architecture type) were constructed. The forecasting ability of each model was assessed by considering coefficient of efficiency (CE), relative time shift error (RTS), and peak water-level error (PE). The results revealed that high CE performance could be achieved by employing more model input variables. Comparisons of the two types of model demonstrated that the NARX-S models outperformed the NARX-P models in terms of CE and RTS, whereas both performed exceptionally in terms of PE and without significant difference. The NARX-S and NARX-P models with the highest overall performance were identified and their predictions were compared with those of traditional ARX-based models. The NARX-S model outperformed the ARX-based models in all three indexes, whereas the NARX-P model exhibited comparable CE performance and superior RTS and PE performance.

  12. The C32 alkane-1,15-diol as a proxy of late Quaternary riverine input in coastal margins

    Science.gov (United States)

    Lattaud, Julie; Dorhout, Denise; Schulz, Hartmut; Castañeda, Isla S.; Schefuß, Enno; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2017-08-01

    The study of past sedimentary records from coastal margins allows us to reconstruct variations in terrestrial input into the marine realm and to gain insight into continental climatic variability. There are numerous organic proxies for tracing terrestrial input into marine environments but none that strictly reflect the input of river-produced organic matter. Here, we test the fractional abundance of the C32 alkane 1,15-diol relative to all 1,13- and 1,15-long-chain diols (FC32 1, 15) as a tracer of input of river-produced organic matter in the marine realm in surface and Quaternary (0-45 ka) sediments on the shelf off the Zambezi and nearby smaller rivers in the Mozambique Channel (western Indian Ocean). A Quaternary (0-22 ka) sediment record off the Nile River mouth in the eastern Mediterranean was also studied for long-chain diols. For the Mozambique Channel, surface sediments of sites most proximal to Mozambique rivers showed the highest F1, 15 - C32 (up to 10 %). The sedimentary record shows high (15-35 %) pre-Holocene F1, 15 - C32 and low (caused the Zambezi River mouth to become more distal to our study site, thereby decreasing riverine input at the core location. Some small discrepancies are observed between the records of the BIT index and FC32 1, 15 for Heinrich Event 1 (H1) and the Younger Dryas (YD), which may be explained by a change in soil sources in the catchment area rather than a change in river influx. Like for the Mozambique Channel, a significant correlation between FC32 1, 15 and the BIT index (r2 = 0.38, p changes in the catchment area.

  13. Reliability analysis of slope stability involving correlated non-normal variables using subset simulation method%含相关非正态变量边坡可靠度分析的子集模拟方法

    Institute of Scientific and Technical Information of China (English)

    张曼; 唐小松; 李典庆

    2012-01-01

    提出了分析含相关非正态变量高维小失效概率可靠度问题的子集模拟方法,采用Nataf变换方法成功地解决了输入变量相关时子集模拟方法样本点的模拟问题.编写了基于MATLAB语言的计算程序SUBSETREL,并以岩质边坡稳定可靠度问题为例证明了所提方法的有效性.结果表明:该子集模拟方法能够有效地分析含相关非正态变量高维小失效概率的边坡可靠度问题.子集模拟方法的计算精度和蒙特卡洛模拟方法相当,计算效率远远高于传统的蒙特卡洛模拟方法.此外,该方法在分析含有复杂的隐式及非线性功能函数的边坡可靠度问题方面体现出明显的优越性.研究成果极大地拓展了子集模拟方法在边坡可靠度分析中的应用.%This paper aims to propose a reliability method named subset simulation(SS) method for estimation of small failure probability in high dimensions of slope stability problems involving correlated non-normal random variables.The Nataf transformation is used to transform the correlated non-normal random variables into the independent standard normal variables,which facilitates the simulation of correlated non-normal samples in failure domain and reliability computation using the SS method.A MATLAB-language based computer program called SUBSETREL is developed to carry out the reliability computations.Two examples of reliability analysis for rock slope stability with plane failure are presented to demonstrate the validity and capability of the proposed method.The results indicate that the proposed SS method can compute small failure probability in high dimensions of rock slope stability involving correlated non-normal random variables accurately and efficiently.Furthermore,the proposed SS method can result in the same accuracy as the traditional Monte Carlo simulations;and its efficiency is significantly higher than the traditional Monte Carlo simulations,which can be considered as

  14. Soil properties and not inputs control carbon : nitrogen : phosphorus ratios in cropped soils in the long term

    Science.gov (United States)

    Frossard, Emmanuel; Buchmann, Nina; Bünemann, Else K.; Kiba, Delwende I.; Lompo, François; Oberson, Astrid; Tamburini, Federica; Traoré, Ouakoltio Y. A.

    2016-02-01

    Stoichiometric approaches have been applied to understand the relationship between soil organic matter dynamics and biological nutrient transformations. However, very few studies have explicitly considered the effects of agricultural management practices on the soil C : N : P ratio. The aim of this study was to assess how different input types and rates would affect the C : N : P molar ratios of bulk soil, organic matter and microbial biomass in cropped soils in the long term. Thus, we analysed the C, N, and P inputs and budgets as well as soil properties in three long-term experiments established on different soil types: the Saria soil fertility trial (Burkina Faso), the Wagga Wagga rotation/stubble management/soil preparation trial (Australia), and the DOK (bio-Dynamic, bio-Organic, and "Konventionell") cropping system trial (Switzerland). In each of these trials, there was a large range of C, N, and P inputs which had a strong impact on element concentrations in soils. However, although C : N : P ratios of the inputs were highly variable, they had only weak effects on soil C : N : P ratios. At Saria, a positive correlation was found between the N : P ratio of inputs and microbial biomass, while no relation was observed between the nutrient ratios of inputs and soil organic matter. At Wagga Wagga, the C : P ratio of inputs was significantly correlated to total soil C : P, N : P, and C : N ratios, but had no impact on the elemental composition of microbial biomass. In the DOK trial, a positive correlation was found between the C budget and the C to organic P ratio in soils, while the nutrient ratios of inputs were not related to those in the microbial biomass. We argue that these responses are due to differences in soil properties among sites. At Saria, the soil is dominated by quartz and some kaolinite, has a coarse texture, a fragile structure, and a low nutrient content. Thus, microorganisms feed on inputs (plant residues, manure). In contrast, the soil at

  15. Genetic Variability, Genotype × Environment Interaction, Correlation, and GGE Biplot Analysis for Grain Iron and Zinc Concentration and Other Agronomic Traits in RIL Population of Sorghum (Sorghum bicolor L. Moench

    Directory of Open Access Journals (Sweden)

    Rahul M. Phuke

    2017-05-01

    Full Text Available The low grain iron and zinc densities are well documented problems in food crops, affecting crop nutritional quality especially in cereals. Sorghum is a major source of energy and micronutrients for majority of population in Africa and central India. Understanding genetic variation, genotype × environment interaction and association between these traits is critical for development of improved cultivars with high iron and zinc. A total of 336 sorghum RILs (Recombinant Inbred Lines were evaluated for grain iron and zinc concentration along with other agronomic traits for 2 years at three locations. The results showed that large variability exists in RIL population for both micronutrients (Iron = 10.8 to 76.4 mg kg−1 and Zinc = 10.2 to 58.7 mg kg−1, across environments and agronomic traits. Genotype × environment interaction for both micronutrients (iron and zinc was highly significant. GGE biplots comparison for grain iron and zinc showed greater variation across environments. The results also showed that G × E was substantial for grain iron and zinc, hence wider testing needed for taking care of G × E interaction to breed micronutrient rich sorghum lines. Iron and zinc concentration showed high significant positive correlation (across environment = 0.79; p < 0.01 indicating possibility of simultaneous effective selection for both the traits. The RIL population showed good variability and high heritabilities (>0.60, in individual environments for Fe and Zn and other traits studied indicating its suitability to map QTL for iron and zinc.

  16. Bilinearity in spatiotemporal integration of synaptic inputs.

    Directory of Open Access Journals (Sweden)

    Songting Li

    2014-12-01

    Full Text Available Neurons process information via integration of synaptic inputs from dendrites. Many experimental results demonstrate dendritic integration could be highly nonlinear, yet few theoretical analyses have been performed to obtain a precise quantitative characterization analytically. Based on asymptotic analysis of a two-compartment passive cable model, given a pair of time-dependent synaptic conductance inputs, we derive a bilinear spatiotemporal dendritic integration rule. The summed somatic potential can be well approximated by the linear summation of the two postsynaptic potentials elicited separately, plus a third additional bilinear term proportional to their product with a proportionality coefficient [Formula: see text]. The rule is valid for a pair of synaptic inputs of all types, including excitation-inhibition, excitation-excitation, and inhibition-inhibition. In addition, the rule is valid during the whole dendritic integration process for a pair of synaptic inputs with arbitrary input time differences and input locations. The coefficient [Formula: see text] is demonstrated to be nearly independent of the input strengths but is dependent on input times and input locations. This rule is then verified through simulation of a realistic pyramidal neuron model and in electrophysiological experiments of rat hippocampal CA1 neurons. The rule is further generalized to describe the spatiotemporal dendritic integration of multiple excitatory and inhibitory synaptic inputs. The integration of multiple inputs can be decomposed into the sum of all possible pairwise integration, where each paired integration obeys the bilinear rule. This decomposition leads to a graph representation of dendritic integration, which can be viewed as functionally sparse.

  17. Population coding in mouse visual cortex: response reliability and dissociability of stimulus tuning and noise correlation

    Directory of Open Access Journals (Sweden)

    Jorrit Steven Montijn

    2014-06-01

    Full Text Available The primary visual cortex is an excellent model system for investigating how neuronal populations encode information, because of well-documented relationships between stimulus characteristics and neuronal activation patterns. We used two-photon calcium imaging data to relate the performance of different methods for studying population coding (population vectors, template matching and Bayesian decoding algorithms to their underlying assumptions. We show that the variability of neuronal responses may hamper the decoding of population activity, and that a normalization to correct for this variability may be of critical importance for correct decoding of population activity. Second, by comparing noise correlations and stimulus tuning we find that these properties have dissociated anatomical correlates, even though noise correlations have been previously hypothesized to reflect common synaptic input. We hypothesize that noise correlations arise from large nonspecific increases in spiking activity acting on many weak synapses simultaneously, while neuronal stimulus response properties are dependent on more reliable connections. Finally, this paper provides practical guidelines for further research on population coding and shows that population coding cannot be approximated by a simple summation of inputs, but is heavily influenced by factors such as input reliability and noise correlation structure.

  18. Population coding in mouse visual cortex: response reliability and dissociability of stimulus tuning and noise correlation.

    Science.gov (United States)

    Montijn, Jorrit S; Vinck, Martin; Pennartz, Cyriel M A

    2014-01-01

    The primary visual cortex is an excellent model system for investigating how neuronal populations encode information, because of well-documented relationships between stimulus characteristics and neuronal activation patterns. We used two-photon calcium imaging data to relate the performance of different methods for studying population coding (population vectors, template matching, and Bayesian decoding algorithms) to their underlying assumptions. We show that the variability of neuronal responses may hamper the decoding of population activity, and that a normalization to correct for this variability may be of critical importance for correct decoding of population activity. Second, by comparing noise correlations and stimulus tuning we find that these properties have dissociated anatomical correlates, even though noise correlations have been previously hypothesized to reflect common synaptic input. We hypothesize that noise correlations arise from large non-specific increases in spiking activity acting on many weak synapses simultaneously, while neuronal stimulus response properties are dependent on more reliable connections. Finally, this paper provides practical guidelines for further research on population coding and shows that population coding cannot be approximated by a simple summation of inputs, but is heavily influenced by factors such as input reliability and noise correlation structure.

  19. Measures of transinformation for multiple input/single output neuronal systems.

    Science.gov (United States)

    Windhorst, U; Schultens, H A

    1982-01-01

    This paper presents a method for the calculation of the information transfer, or transinformation, in multiple input/single output neuronal systems. Our approach is an extension of an approach introduced by Eckhorn and Poepel in 1974. These authors computed the transinformation in single input/single output neuronal channels by regarding the spike (or stimulus) trains involved as finite Markov chains. The expressions for multiple input systems presented here are derived in close analogy to formulae in linear systems theory which show explicitly the correlations between the different input channels. A number of equivalent forms for the transinformation are discussed.

  20. Examining Correlates of Diversity.

    Science.gov (United States)

    Raudenbush, Stephen W.; Bryk, Anthony S.

    1987-01-01

    Statistical methods are presented for studying "correlates of diversity," defined as characteristics of educational organizations that predict dispersion on the dependent variable. Strategies based on exact distribution theory and asymptotic normal approximation are considered. (TJH)

  1. Rapid Airplane Parametric Input Design (RAPID)

    Science.gov (United States)

    Smith, Robert E.

    1995-01-01

    RAPID is a methodology and software system to define a class of airplane configurations and directly evaluate surface grids, volume grids, and grid sensitivity on and about the configurations. A distinguishing characteristic which separates RAPID from other airplane surface modellers is that the output grids and grid sensitivity are directly applicable in CFD analysis. A small set of design parameters and grid control parameters govern the process which is incorporated into interactive software for 'real time' visual analysis and into batch software for the application of optimization technology. The computed surface grids and volume grids are suitable for a wide range of Computational Fluid Dynamics (CFD) simulation. The general airplane configuration has wing, fuselage, horizontal tail, and vertical tail components. The double-delta wing and tail components are manifested by solving a fourth order partial differential equation (PDE) subject to Dirichlet and Neumann boundary conditions. The design parameters are incorporated into the boundary conditions and therefore govern the shapes of the surfaces. The PDE solution yields a smooth transition between boundaries. Surface grids suitable for CFD calculation are created by establishing an H-type topology about the configuration and incorporating grid spacing functions in the PDE equation for the lifting components and the fuselage definition equations. User specified grid parameters govern the location and degree of grid concentration. A two-block volume grid about a configuration is calculated using the Control Point Form (CPF) technique. The interactive software, which runs on Silicon Graphics IRIS workstations, allows design parameters to be continuously varied and the resulting surface grid to be observed in real time. The batch software computes both the surface and volume grids and also computes the sensitivity of the output grid with respect to the input design parameters by applying the precompiler tool

  2. Computing Functions by Approximating the Input

    Science.gov (United States)

    Goldberg, Mayer

    2012-01-01

    In computing real-valued functions, it is ordinarily assumed that the input to the function is known, and it is the output that we need to approximate. In this work, we take the opposite approach: we show how to compute the values of some transcendental functions by approximating the input to these functions, and obtaining exact answers for their…

  3. Wave energy input into the Ekman layer

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper is concerned with the wave energy input into the Ekman layer, based on 3 observational facts that surface waves could significantly affect the profile of the Ekman layer. Under the assumption of constant vertical diffusivity, the analytical form of wave energy input into the Ekman layer is derived. Analysis of the energy balance shows that the energy input to the Ekman layer through the wind stress and the interaction of the Stokes-drift with planetary vorticity can be divided into two kinds. One is the wind energy input, and the other is the wave energy input which is dependent on wind speed, wave characteristics and the wind direction relative to the wave direction. Estimates of wave energy input show that wave energy input can be up to 10% in high-latitude and high-wind speed areas and higher than 20% in the Antarctic Circumpolar Current, compared with the wind energy input into the classical Ekman layer. Results of this paper are of significance to the study of wave-induced large scale effects.

  4. Correlated Multiphoton Holes

    CERN Document Server

    Afek, Itai; Silberberg, Yaron

    2010-01-01

    We generate bipartite states of light which exhibit an absence of multiphoton coincidence events between two modes amid a constant background flux. These `correlated photon holes' are produced by mixing a coherent state and relatively weak spontaneous parametric down-conversion using a balanced beamsplitter. Correlated holes with arbitrarily high photon numbers may be obtained by adjusting the relative phase and amplitude of the inputs. We measure states of up to five photons and verify their nonclassicality. The scheme provides a route for observation of high-photon-number nonclassical correlations without requiring intense quantum resources.

  5. Determining the input dimension of a neural network for nonlinear time series prediction

    Institute of Scientific and Technical Information of China (English)

    张胜; 刘红星; 高敦堂; 都思丹

    2003-01-01

    Determining the input dimension of a feed-forward neural network for nonlinear time series prediction plays an important role in the modelling.The paper first summarizes the current methods for determining the input dimension of the neural network.Then inspired by the fact that the correlation dimension of a nonlinear dynamic system is the mostimportant feature of it,the paper presents a new idea that the input dimension of the neural network for nonlinear time series prediction can be taken as an integer just greater than or equal to the correlation dimension.Finally,some wlidation examples and results are given.

  6. Atmospheric Nitrogen input to the Kattegat

    DEFF Research Database (Denmark)

    Asman, W.A.H.; Hertel, O.; Berkowicz, R.

    1995-01-01

    An overview is given of the processes involved in the atmospheric deposition of nitrogen compounds. These processes are incorporated in an atmospheric transport model that is used to calculate the nitrogen input to the Kattegat, the sea area between Denmark and Sweden. The model results show...... that the total atmospheric nitrogen input to the Kattegat is approximately 960 kg N km(-2) yr(-1). The nitrogen input to the Kattegat is dominated by the wet depositions of NHx (42%) and NOy (30%). The contribution from the dry deposition of NHx is 17% and that of the dry deposition of NOy is 11......%. The contribution of the atmospheric input of nitrogen to the Kattegat is about 30% of the total input including the net transport from other sea areas, runoff etc....

  7. Input impedance characteristics of microstrip structures

    Directory of Open Access Journals (Sweden)

    A. I. Nazarko

    2015-06-01

    Full Text Available Introduction. Electromagnetic crystals (EC and EC-inhomogeneities are one of the main directions of microstrip devices development. In the article the input impedance characteristics of EC- and traditional microstrip inhomogeneities and filter based on EC-inhomogeneities are investigated. Transmission coefficient characteristics. Transmission coefficient characteristics of low impedance EC- and traditional inhomogeneities are considered. Characteristics are calculated in the software package Microwave Studio. It is shown that the efficiency of EC-inhomogeneity is much higher. Input impedance characteristics of low impedance inhomogeneities. Dependences of input impedance active and reactive parts of EC- and traditional inhomogeneities are given. Dependences of the active part illustrate significant low impedance transformation of nominal impedance. The conditions of impedance matching of structure and input medium are set. Input impedance characteristics of high impedance inhomogeneities. Input impedance characteristics of high impedance EC- and traditional inhomogeneities are considered. It was shown that the band of transformation by high impedance inhomogeneities is much narrower than one by low impedance inhomogeneities. Characteristics of the reflection coefficient of inhomogeneities are presented. Input impedance characteristics of narrowband filter. The structure of narrowband filter based on the scheme of Fabry-Perot resonator is presented. The structure of the filter is fulfilled by high impedance EC-inhomogeneities as a reflectors. Experimental and theoretical amplitude-frequency characteristics of the filter are presented. Input impedance characteristics of the filter are shown. Conclusions. Input impedance characteristics of the structure allow to analyse its wave properties, especially resonant. EC-inhomogeneity compared with traditional microstrip provide substantially more significant transformation of the the input impedance.

  8. A linearized input-output representation of flexible multibody systems for control synthesis

    NARCIS (Netherlands)

    Jonker, Jan B.; Aarts, Ronald G.K.M.; van Dijk, Johannes

    2009-01-01

    In this paper, a linearized input–output representation of flexible multibody systems is proposed in which an arbitrary combination of positions, velocities, accelerations, and forces can be taken as input variables and as output variables. The formulation is based on a nonlinear finite element

  9. COMPARING THE IMPACT OF ACCURATE INPUTS ON NEURAL NETWORKS

    Directory of Open Access Journals (Sweden)

    V.Vaithiyanathan

    2013-06-01

    Full Text Available Artificial neural networks are widely used in medical diagnosis replacing most of the conventional diagnosis methods due to its accuracy and speed. This paper analyses the variation in theaccuracy of diagnosis of type II diabetes using Artificial Neural Networks based on the accuracy of the inputs given to the network. It compares the efficiency of the network based on the input format. Thedata needed for this comparison is collected by interviewing patients who approach the diabetician with various symptoms of the disease. These symptoms can be modeled in 2 different forms. One form justspecifies the presence or absence of the symptom and can be represented using Boolean values. The other form specifies the severity or frequency of occurrence of the symptom. Both these inputs are given to the system and the accuracy of the output is analyzed. This result indicates the impact of the specification of the input on the output. Comparison is done by performing regression analysis on both the outputs. Regression analysis gives the correlation between the output of the system and the target [1]. It makes use of only the most general symptoms of the disease. Further analysis can be done on other diabetes particular symptoms.

  10. Integrate-and-fire vs Poisson models of LGN input to V1 cortex: noisier inputs reduce orientation selectivity.

    Science.gov (United States)

    Lin, I-Chun; Xing, Dajun; Shapley, Robert

    2012-12-01

    One of the reasons the visual cortex has attracted the interest of computational neuroscience is that it has well-defined inputs. The lateral geniculate nucleus (LGN) of the thalamus is the source of visual signals to the primary visual cortex (V1). Most large-scale cortical network models approximate the spike trains of LGN neurons as simple Poisson point processes. However, many studies have shown that neurons in the early visual pathway are capable of spiking with high temporal precision and their discharges are not Poisson-like. To gain an understanding of how response variability in the LGN influences the behavior of V1, we study response properties of model V1 neurons that receive purely feedforward inputs from LGN cells modeled either as noisy leaky integrate-and-fire (NLIF) neurons or as inhomogeneous Poisson processes. We first demonstrate that the NLIF model is capable of reproducing many experimentally observed statistical properties of LGN neurons. Then we show that a V1 model in which the LGN input to a V1 neuron is modeled as a group of NLIF neurons produces higher orientation selectivity than the one with Poisson LGN input. The second result implies that statistical characteristics of LGN spike trains are important for V1's function. We conclude that physiologically motivated models of V1 need to include more realistic LGN spike trains that are less noisy than inhomogeneous Poisson processes.

  11. Numeric Input Relations for Relational Learning with Applications to Community Structure Analysis

    DEFF Research Database (Denmark)

    Jiang, Jiuchuan; Jaeger, Manfred

    2015-01-01

    distribution is defined by the model from numerical input variables that are only used for conditioning the distribution of discrete response variables. We show how numerical input relations can very easily be used in the Relational Bayesian Network framework, and that existing inference and learning methods......Most work in the area of statistical relational learning (SRL) is focussed on discrete data, even though a few approaches for hybrid SRL models have been proposed that combine numerical and discrete variables. In this paper we distinguish numerical random variables for which a probability...... need only minor adjustments to be applied in this generalized setting. The resulting framework provides natural relational extensions of classical probabilistic models for categorical data. We demonstrate the usefulness of RBN models with numeric input relations by several examples. In particular, we...

  12. Quantitative amyloid imaging using image-derived arterial input function.

    Directory of Open Access Journals (Sweden)

    Yi Su

    Full Text Available Amyloid PET imaging is an indispensable tool widely used in the investigation, diagnosis and monitoring of Alzheimer's disease (AD. Currently, a reference region based approach is used as the mainstream quantification technique for amyloid imaging. This approach assumes the reference region is amyloid free and has the same tracer influx and washout kinetics as the regions of interest. However, this assumption may not always be valid. The goal of this work is to evaluate an amyloid imaging quantification technique that uses arterial region of interest as the reference to avoid potential bias caused by specific binding in the reference region. 21 participants, age 58 and up