WorldWideScience

Sample records for bimodal correlated random

  1. Robustness analysis of bimodal networks in the whole range of degree correlation

    CERN Document Server

    Mizutaka, Shogo

    2016-01-01

    We present exact analysis of the physical properties of bimodal networks specified by the two peak degree distribution fully incorporating the degree-degree correlation between node connection. The structure of the correlated bimodal network is uniquely determined by the Pearson coefficient of the degree correlation, keeping its degree distribution fixed. The percolation threshold and the giant component fraction of the correlated bimodal network are analytically calculated in the whole range of the Pearson coefficient from $-1$ to $1$ against two major types of node removal, which are the random failure and the degree-based targeted attack. The Pearson coefficient for next-nearest-neighbor pairs is also calculated, which always takes a positive value even when the correlation between nearest-neighbor pairs is negative. From the results, it is confirmed that the percolation threshold is a monotonically decreasing function of the Pearson coefficient for the degrees of nearest-neighbor pairs increasing from $-1...

  2. Robustness analysis of bimodal networks in the whole range of degree correlation

    OpenAIRE

    Mizutaka, Shogo; Tanizawa, Toshihiro

    2016-01-01

    We present exact analysis of the physical properties of bimodal networks specified by the two peak degree distribution fully incorporating the degree-degree correlation between node connection. The structure of the correlated bimodal network is uniquely determined by the Pearson coefficient of the degree correlation, keeping its degree distribution fixed. The percolation threshold and the giant component fraction of the correlated bimodal network are analytically calculated in the whole range...

  3. Recognition of Emotions using Energy Based Bimodal Information Fusion and Correlation

    Directory of Open Access Journals (Sweden)

    Krishna Asawa

    2014-09-01

    Full Text Available Multi-sensor information fusion is a rapidly developing research area which forms the backbone of numerous essential technologies such as intelligent robotic control, sensor networks, video and image processing and many more. In this paper, we have developed a novel technique to analyze and correlate human emotions expressed in voice tone & facial expression. Audio and video streams captured to populate audio and video bimodal data sets to sense the expressed emotions in voice tone and facial expression respectively. An energy based mapping is being done to overcome the inherent heterogeneity of the recorded bi-modal signal. The fusion process uses sampled and mapped energy signal of both modalities’s data stream and further recognize the overall emotional component using Support Vector Machine (SVM classifier with the accuracy 93.06%

  4. Wang-Landau study of the critical behaviour of the bimodal 3D-Random Field Ising Model

    OpenAIRE

    Hernandez, Laura; Ceva, Horacio

    2007-01-01

    We apply the Wang-Landau method to the study of the critical behaviour of the three dimensional Random Field Ising Model with a bimodal probability distribution. Our results show that for high values of the random field intensity the transition is first order, characterized by a double-peaked energy probability distribution at the transition temperature. On the other hand, the transition looks continuous for low values of the field intensity. In spite of the large sample to sample fluctuation...

  5. Correlated randomness and switching phenomena

    Science.gov (United States)

    Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Kumar, P.; Plerou, V.; Preis, T.

    2010-08-01

    One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines have no perfect metronome in time and no perfect spatial architecture-crystalline or otherwise. Nonetheless, as if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time and remarkably fine-tuned structures in space. Further, many of these processes and structures have the remarkable feature of “switching” from one behavior to another as if by magic. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many spatial and temporal patterns in biology, medicine, and economics and even begin to characterize the switching phenomena that enables a system to pass from one state to another. Inspired by principles developed by A. Nihat Berker and scores of other statistical physicists in recent years, we discuss some applications of correlated randomness to understand switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water’s anomalies are related to a switching point (which is not unlike the “tipping point” immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not “outliers” (another Gladwell immortalization). Though more speculative, we support the idea of disease as arising from some kind of yet-to-be-understood complex switching phenomenon, by discussing data on selected examples, including heart disease and Alzheimer disease.

  6. Communication Requirements for Generating Correlated Random Variables

    CERN Document Server

    Cuff, Paul

    2008-01-01

    Two familiar notions of correlation are rediscovered as extreme operating points for simulating a discrete memoryless channel, in which a channel output is generated based only on a description of the channel input. Wyner's "common information" coincides with the minimum description rate needed. However, when common randomness independent of the input is available, the necessary description rate reduces to Shannon's mutual information. This work characterizes the optimal tradeoff between the amount of common randomness used and the required rate of description.

  7. Random Correlation Matrix and De-Noising

    OpenAIRE

    Ken-ichi Mitsui; Yoshio Tabata

    2006-01-01

    In Finance, the modeling of a correlation matrix is one of the important problems. In particular, the correlation matrix obtained from market data has the noise. Here we apply the de-noising processing based on the wavelet analysis to the noisy correlation matrix, which is generated by a parametric function with random parameters. First of all, we show that two properties, i.e. symmetry and ones of all diagonal elements, of the correlation matrix preserve via the de-noising processing and the...

  8. Correlations and fractality in random Ising magnets

    OpenAIRE

    Nowak, Ulrich; Usadel, Klaus-Dieter

    1992-01-01

    We investigate the behavior of domains in random Ising magnets by a Monte Carlo simulation. We calculate the spatial correlation function of the frozen domain state of two- and three-dimensional diluted antiferromagnets in an external magnetic field and compare the results with those line shapes found from neutron scattering experiments. An analysis leads to a new interpretation of the corresponding correlation length in terms of fractality and interpretation in the structure of the domains.

  9. Dynamical correlations among vicious random walkers

    International Nuclear Information System (INIS)

    Nonintersecting motion of Brownian particles in one dimension is studied. The system is constructed as the diffusion scaling limit of Fisher's vicious random walk. N particles start from the origin at time t=0 and then undergo mutually avoiding Brownian motion until a finite time t=T. In the short time limit t<< T, the particle distribution is asymptotically described by Gaussian Unitary Ensemble (GUE) of random matrices. At the end time t=T, it is identical to that of Gaussian Orthogonal Ensemble (GOE). We show that the most general dynamical correlations among arbitrary number of particles at arbitrary number of times are written in the forms of quaternion determinants. Asymptotic forms of the correlations in the limit N→∞ are evaluated and a discontinuous transition of the universality class from GUE to GOE is observed

  10. Testing the correlated random coefficient model

    OpenAIRE

    Heckman, James J.; Schmierer, Daniel; Urzua, Sergio

    2010-01-01

    The recent literature on instrumental variables (IV) features models in which agents sort into treatment status on the basis of gains from treatment as well as on baseline-pretreatment levels. Components of the gains known to the agents and acted on by them may not be known by the observing economist. Such models are called correlated random coefficient models. Sorting on unobserved components of gains complicates the interpretation of what IV estimates. This paper examines testable implicati...

  11. Hierarchical pinning model in correlated random environment

    CERN Document Server

    Berger, Quentin

    2011-01-01

    We consider the hierarchical disordered pinning model studied in [9], which exhibits a localization/delocalization phase transition. In the case where the disorder is i.i.d. (independent and identically distributed), the question of relevance/irrelevance of disorder (i.e. whether disorder changes or not the critical properties with respect to the homogeneous case) is by now mathematically rather well understood [14,15]. Here we consider the case where randomness is spatially correlated and correlations respect the hierarchical structure of the model; in the non-hierarchical model our choice would correspond to a power-law decay of correlations. In terms of the critical exponent of the homogeneous model and of the correlation decay exponent, we identify three regions. In the first one (non-summable correlations) the phase transition disappears. In the second one (correlations decaying fast enough) the system behaves essentially like in the i.i.d. setting and the relevance/irrelevance criterion is not modified....

  12. Static correlation beyond the random phase approximation

    DEFF Research Database (Denmark)

    Olsen, Thomas; Thygesen, Kristian Sommer

    2014-01-01

    derived from Hedin's equations (Random Phase Approximation (RPA), Time-dependent Hartree-Fock (TDHF), Bethe-Salpeter equation (BSE), and Time-Dependent GW) all reproduce the correct dissociation limit. We also show that the BSE improves the correlation energies obtained within RPA and TDHF significantly...... for intermediate binding distances. A Hubbard model for the dimer allows us to obtain exact analytical results for the various approximations, which is readily compared with the exact diagonalization of the model. Moreover, the model is shown to reproduce all the qualitative results from the ab initio...

  13. Understanding deterministic diffusion by correlated random walks

    International Nuclear Information System (INIS)

    Low-dimensional periodic arrays of scatterers with a moving point particle are ideal models for studying deterministic diffusion. For such systems the diffusion coefficient is typically an irregular function under variation of a control parameter. Here we propose a systematic scheme of how to approximate deterministic diffusion coefficients of this kind in terms of correlated random walks. We apply this approach to two simple examples which are a one-dimensional map on the line and the periodic Lorentz gas. Starting from suitable Green-Kubo formulae we evaluate hierarchies of approximations for their parameter-dependent diffusion coefficients. These approximations converge exactly yielding a straightforward interpretation of the structure of these irregular diffusion coefficients in terms of dynamical correlations. (author)

  14. Tests of Hypotheses Arising in the Correlated Random Coefficient Model

    OpenAIRE

    Heckman, James J.; Schmierer, Daniel

    2010-01-01

    This paper examines the correlated random coefficient model. It extends the analysis of Swamy (1971, 1974), who pioneered the uncorrelated random coefficient model in economics. We develop the properties of the correlated random coefficient model and derive a new representation of the variance of the instrumental variable estimator for that model. We develop tests of the validity of the correlated random coefficient model against the null hypothesis of the uncorrelated random coefficient model.

  15. A bimodal correlation between host star chromospheric emission and the surface gravity of hot Jupiters

    CERN Document Server

    Fossati, L; Lanza, A F

    2015-01-01

    The chromospheric activity index logR'HK of stars hosting transiting hot Jupiters appears to be correlated with the planets' surface gravity. One of the possible explanations is based on the presence of condensations of planetary evaporated material located in a circumstellar cloud that absorbs the CaII H&K and MgII h&k resonance line emission flux, used to measure chromospheric activity. A larger column density in the condensations, or equivalently a stronger absorption in the chromospheric lines, is obtained when the evaporation rate of the planet is larger, which occurs for a lower gravity of the planet. We analyze here a sample of stars hosting transiting hot Jupiters tuned in order to minimize systematic effects (e.g., interstellar medium absorption). Using a mixture model, we find that the data are best fit by a two-linear-regression model. We interpret this result in terms of the Vaughan-Preston gap. We use a Monte Carlo approach to best take into account the uncertainties, finding that the two...

  16. Bimodal Bilingualism

    Science.gov (United States)

    Emmorey, Karen; Borinstein, Helsa B.; Thompson, Robin; Gollan, Tamar H.

    2008-01-01

    Speech-sign or "bimodal" bilingualism is exceptional because distinct modalities allow for simultaneous production of two languages. We investigated the ramifications of this phenomenon for models of language production by eliciting language mixing from eleven hearing native users of American Sign Language (ASL) and English. Instead of switching…

  17. The 20th anniversary of interleukin-2 therapy: bimodal role explaining longstanding random induction of complete clinical responses

    Directory of Open Access Journals (Sweden)

    Coventry BJ

    2012-08-01

    Full Text Available Brendon J Coventry, Martin L AshdownDiscipline of Surgery, University of Adelaide, Royal Adelaide Hospital and Faculty of Medicine, University of Melbourne, AustraliaBackground: This year marks the twentieth anniversary of the approval by the US Food and Drug Administration of interleukin-2 (IL2 for use in cancer therapy, initially for renal cell carcinoma and later for melanoma. IL2 therapy for cancer has stood the test of time, with continued widespread use in Europe, parts of Asia, and the US. Clinical complete responses are variably reported at 5%–20% for advanced malignant melanoma and renal cell carcinoma, with strong durable responses and sustained long-term 5–10-year survival being typical if complete responses are generated.Methods: The literature was reviewed for the actions and clinical effects of IL2 on subsets of T cells. The influence of IL2 on clinical efficacy was also sought.Results: The review revealed that IL2 is capable of stimulating different populations of T cells in humans to induce either T effector or T regulatory responses. This apparent "functional paradox" has confounded a clear understanding of the mechanisms behind the clinical effects that are observed during and following administration of IL2 therapy. An average complete response rate of around 7% in small and large clinical trials using IL2 for advanced renal cell carcinoma and malignant melanoma has been shown from a recent review of the literature.Conclusion: This review considers the published literature concerning the actions and emerging clinical effects of IL2 therapy, spanning its 20-year period in clinical use. It further details some of the recently described "bimodal" effects of IL2 to explain the apparent functional paradox, and how IL2 might be harnessed to emerge rapidly as a much more effective and predictable clinical agent in the near future.Keywords: interleukin-2, cancer therapy, immunotherapy, immune response, translational research

  18. A Note on the Correlated Random Coefficient Model

    DEFF Research Database (Denmark)

    Kolodziejczyk, Christophe

    In this note we derive the bias of the OLS estimator for a correlated random coefficient model with one random coefficient, but which is correlated with a binary variable. We provide set-identification to the parameters of interest of the model. We also show how to reduce the bias of the estimator...

  19. Statistical theory of correlations in random packings of hard particles

    OpenAIRE

    Jin, Yuliang; Puckett, James G.; Makse, Hernan A.

    2014-01-01

    A random packing of hard particles represents a fundamental model for granular matter. Despite its importance, analytical modeling of random packings remains difficult due to the existence of strong correlations which preclude the development of a simple theory. Here, we take inspiration from liquid theories for the $n$-particle angular correlation function to develop a formalism of random packings of hard particles from the bottom-up. A progressive expansion into a shell of particles converg...

  20. Statistical theory of correlations in random packings of hard particles.

    Science.gov (United States)

    Jin, Yuliang; Puckett, James G; Makse, Hernán A

    2014-05-01

    A random packing of hard particles represents a fundamental model for granular matter. Despite its importance, analytical modeling of random packings remains difficult due to the existence of strong correlations which preclude the development of a simple theory. Here, we take inspiration from liquid theories for the n-particle angular correlation function to develop a formalism of random packings of hard particles from the bottom up. A progressive expansion into a shell of particles converges in the large layer limit under a Kirkwood-like approximation of higher-order correlations. We apply the formalism to hard disks and predict the density of two-dimensional random close packing (RCP), ϕ(rcp) = 0.85 ± 0.01, and random loose packing (RLP), ϕ(rlp) = 0.67 ± 0.01. Our theory also predicts a phase diagram and angular correlation functions that are in good agreement with experimental and numerical data. PMID:25353787

  1. Infinite range correlations of intensity in random media

    Indian Academy of Sciences (India)

    A Retzker; B Shapiro

    2002-02-01

    We study a new type of long-range correlations for waves propagating in a random medium. These correlations originate from scattering events which take place close to a point source. The scattered waves propagate by diffusion to distant regions. In this way long range correlations, between any pair of distant points, are established.

  2. Eigenvalue correlations in non-Hermitean symplectic random matrices

    International Nuclear Information System (INIS)

    A correlation function of complex eigenvalues of NxN random matrices drawn from non-Hermitean random matrix ensembles of symplectic symmetry is given in terms of a quaternion determinant. Spectral properties of Gaussian ensembles are studied in detail in the regimes of weak and strong non-Hermiticity. (author)

  3. Spatial versus sequential correlations for random access coding

    Science.gov (United States)

    Tavakoli, Armin; Marques, Breno; Pawłowski, Marcin; Bourennane, Mohamed

    2016-03-01

    Random access codes are important for a wide range of applications in quantum information. However, their implementation with quantum theory can be made in two very different ways: (i) by distributing data with strong spatial correlations violating a Bell inequality or (ii) using quantum communication channels to create stronger-than-classical sequential correlations between state preparation and measurement outcome. Here we study this duality of the quantum realization. We present a family of Bell inequalities tailored to the task at hand and study their quantum violations. Remarkably, we show that the use of spatial and sequential quantum correlations imposes different limitations on the performance of quantum random access codes: Sequential correlations can outperform spatial correlations. We discuss the physics behind the observed discrepancy between spatial and sequential quantum correlations.

  4. Information cascades on degree-correlated random networks

    Science.gov (United States)

    Payne, Joshua L.; Dodds, Peter Sheridan; Eppstein, Margaret J.

    2009-08-01

    We investigate by numerical simulation a threshold model of social contagion on degree-correlated random networks. We show that the class of networks for which global information cascades occur generally expands as degree-degree correlations become increasingly positive. However, under certain conditions, large-scale information cascades can paradoxically occur when degree-degree correlations are sufficiently positive or negative, but not when correlations are relatively small. We also show that the relationship between the degree of the initially infected vertex and its ability to trigger large cascades is strongly affected by degree-degree correlations.

  5. Entropy and long-range correlations in random symbolic sequences

    CERN Document Server

    Melnik, S S

    2014-01-01

    The goal of this paper is to develop an estimate for the entropy of random long-range correlated symbolic sequences with elements belonging to a finite alphabet. As a plausible model, we use the high-order additive stationary ergodic Markov chain. Supposing that the correlations between random elements of the chain are weak we express the differential entropy of the sequence by means of the symbolic pair correlation function. We also examine an algorithm for estimating the differential entropy of finite symbolic sequences. We show that the entropy contains two contributions, the correlation and fluctuation ones. The obtained analytical results are used for numerical evaluation of the entropy of written English texts and DNA nucleotide sequences. The developed theory opens the way for constructing a more consistent and sophisticated approach to describe the systems with strong short- and weak long-range correlations.

  6. Correlated randomness: Some examples of exotic statistical physics

    Indian Academy of Sciences (India)

    H Eugene Stanley

    2005-05-01

    One challenge of biology, medicine, and economics is that the systems treated by these sciences have no perfect metronome in time and no perfect spatial architecture – crystalline or otherwise. Nonetheless, as if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time and remarkably fine-tuned structures in space. To understand this `miracle', one might consider placing aside the human tendency to see the universe as a machine. Instead, one might address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at many spatial and temporal patterns in biology, medicine, and economics. Inspired by principles developed by statistical physics over the past 50 years – scale invariance and universality – we review some recent applications of correlated randomness to fields that might startle Boltzmann if he were alive today.

  7. Statistics of branched flow in a weak correlated random potential

    OpenAIRE

    Kaplan, Lev

    2002-01-01

    Recent images of electron flow through a two-dimensional electron gas (2DEG) device show branching behavior that is reproduced in numerical simulations of motion in a correlated random potential [cond-mat/0010348]. We show how such branching naturally arises from caustics in the classical flow and find a simple scaling behavior of the branching under variation of the random potential strength. Analytic results describing the statistical properties of the branching are confirmed by classical a...

  8. On the Power of Correlated Randomness in Secure Computation

    DEFF Research Database (Denmark)

    Ishai, Yuval; Kushilevitz, Eyal; Meldgaard, Sigurd Torkel;

    2013-01-01

    positive and negative results on unconditionally secure computation with correlated randomness. Concretely, we obtain the following results. Minimizing communication. Any multiparty functionality can be realized, with perfect security against semi-honest parties or statistical security against malicious......We investigate the extent to which correlated secret randomness can help in secure computation with no honest majority. It is known that correlated randomness can be used to evaluate any circuit of size s with perfect security against semi-honest parties or statistical security against malicious...... parties, where the communication complexity grows linearly with s. This leaves open two natural questions: (1) Can the communication complexity be made independent of the circuit size? (2) Is it possible to obtain perfect security against malicious parties? We settle the above questions, obtaining both...

  9. Multivariate Tests for Correlated Data in Completely Randomized Designs.

    Science.gov (United States)

    Mielke, Paul W., Jr.; Berry, Kenneth J.

    1999-01-01

    Provides power comparisons for three permutation tests and the Bartlett-Nanda-Pillai trace test (BNP) (M. Bartlett, 1939; D. Nanda, 1950; K. Pillai, 1955) in completely randomized experimental designs with correlated multivariate-dependent variables. The power of the BNP was generally found to be less than that of at least one of the permutation…

  10. Apparent scale correlations in a random multifractal process

    DEFF Research Database (Denmark)

    Cleve, Jochen; Schmiegel, Jürgen; Greiner, Martin

    2008-01-01

    We discuss various properties of a homogeneous random multifractal process, which are related to the issue of scale correlations. By design, the process has no built-in scale correlations. However, when it comes to observables like breakdown coefficients, which are based on a coarse-graining of the...... multifractal field, scale correlations do appear. In the log-normal limit of the model process, the conditional distributions and moments of breakdown coefficients reproduce the observations made in fully developed small-scale turbulence. These findings help to understand several puzzling empirical details...

  11. 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.

  12. 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.

  13. Calibration of Correlation Radiometers Using Pseudo-Random Noise Signals

    Directory of Open Access Journals (Sweden)

    Sebastián Pantoja

    2009-08-01

    Full Text Available The calibration of correlation radiometers, and particularly aperture synthesis interferometric radiometers, is a critical issue to ensure their performance. Current calibration techniques are based on the measurement of the cross-correlation of receivers’ outputs when injecting noise from a common noise source requiring a very stable distribution network. For large interferometric radiometers this centralized noise injection approach is very complex from the point of view of mass, volume and phase/amplitude equalization. Distributed noise injection techniques have been proposed as a feasible alternative, but are unable to correct for the so-called “baseline errors” associated with the particular pair of receivers forming the baseline. In this work it is proposed the use of centralized Pseudo-Random Noise (PRN signals to calibrate correlation radiometers. PRNs are sequences of symbols with a long repetition period that have a flat spectrum over a bandwidth which is determined by the symbol rate. Since their spectrum resembles that of thermal noise, they can be used to calibrate correlation radiometers. At the same time, since these sequences are deterministic, new calibration schemes can be envisaged, such as the correlation of each receiver’s output with a baseband local replica of the PRN sequence, as well as new distribution schemes of calibration signals. This work analyzes the general requirements and performance of using PRN sequences for the calibration of microwave correlation radiometers, and particularizes the study to a potential implementation in a large aperture synthesis radiometer using an optical distribution network.

  14. 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.

  15. New correlation functions for random matrices and integrals over supergroups

    International Nuclear Information System (INIS)

    The averages of ratios of characteristic polynomials det(λ - X) of N x N random matrices X are investigated in the large-N limit for the GUE, GOE and GSE ensembles. The density of states and the two-point correlation function are derived from these ratios. The method relies on an extension of the Harish-Chandra, Itzykson, Zuber integrals to the GOE ensemble and to supergroups, which are explicitly computed through heat kernel differential equations. An external matrix source, linearly coupled to the random matrices, may also be added to the Gaussian distribution, and allows for a discussion of the universality of the GOE results in the large-N limit

  16. Correlated continuous time random walk and option pricing

    Science.gov (United States)

    Lv, Longjin; Xiao, Jianbin; Fan, Liangzhong; Ren, Fuyao

    2016-04-01

    In this paper, we study a correlated continuous time random walk (CCTRW) with averaged waiting time, whose probability density function (PDF) is proved to follow stretched Gaussian distribution. Then, we apply this process into option pricing problem. Supposing the price of the underlying is driven by this CCTRW, we find this model captures the subdiffusive characteristic of financial markets. By using the mean self-financing hedging strategy, we obtain the closed-form pricing formulas for a European option with and without transaction costs, respectively. At last, comparing the obtained model with the classical Black-Scholes model, we find the price obtained in this paper is higher than that obtained from the Black-Scholes model. A empirical analysis is also introduced to confirm the obtained results can fit the real data well.

  17. Sharp critical behavior for pinning model in random correlated environment

    CERN Document Server

    Berger, Quentin

    2011-01-01

    This article investigates the effect for random pinning models of long range power-law decaying correlations in the environment. For a particular type of environment based on a renewal construction, we are able to sharply describe the phase transition from the delocalized phase to the localized one, giving the critical exponent for the (quenched) free-energy, and proving that at the critical point the trajectories are fully delocalized. These results contrast with what happens both for the pure model (i.e. without disorder) and for the widely studied case of i.i.d. disorder, where the relevance or irrelevance of disorder on the critical properties is decided via the so-called Harris Criterion.

  18. Correlated random walks caused by dynamical wavefunction collapse.

    Science.gov (United States)

    Bedingham, D J; Ulbricht, H

    2015-01-01

    Wavefunction collapse models modify Schrödinger's equation so that it describes the collapse of a superposition of macroscopically distinguishable states as a dynamical process. This provides a basis for the resolution of the quantum measurement problem. An additional generic consequence of the collapse mechanism is that it causes particles to exhibit a tiny random diffusive motion. Here it is shown that for the continuous spontaneous localization (CSL) model—one of the most well developed collapse models—the diffusions of two sufficiently nearby particles are positively correlated. An experimental test of this effect is proposed in which random displacements of pairs of free nanoparticles are measured after they have been simultaneously released from nearby traps. The experiment must be carried out at sufficiently low temperature and pressure in order for the collapse effects to dominate over the ambient environmental noise. It is argued that these constraints can be satisfied by current technologies for a large region of the viable parameter space of the CSL model. The effect disappears as the separation between particles exceeds the CSL length scale. The test therefore provides a means of bounding this length scale. PMID:26303388

  19. Effects of random rewiring on the degree correlation of scale-free networks

    Science.gov (United States)

    Qu, Jing; Wang, Sheng-Jun; Jusup, Marko; Wang, Zhen

    2015-10-01

    Random rewiring is used to generate null networks for the purpose of analyzing the topological properties of scale-free networks, yet the effects of random rewiring on the degree correlation are subject to contradicting interpretations in the literature. We comprehensively analyze the degree correlation of randomly rewired scale-free networks and show that random rewiring increases disassortativity by reducing the average degree of the nearest neighbors of high-degree nodes. The effect can be captured by the measures of the degree correlation that consider all links in the network, but not by analogous measures that consider only links between degree peers, hence the potential for contradicting interpretations. We furthermore find that random and directional rewiring affect the topology of a scale-free network differently, even if the degree correlation of the rewired networks is the same. Consequently, the network dynamics is changed, which is proven here by means of the biased random walk.

  20. On the analytic representation of the correlation function of linear random vibration systems

    OpenAIRE

    Gruner, J; Scheidt, J. vom; Wunderlich, R.

    1998-01-01

    This paper is devoted to the computation of statistical characteristics of the response of discrete vibration systems with a random external excitation. The excitation can act at multiple points and is modeled by a time-shifted random process and its derivatives up to the second order. Statistical characteristics of the response are given by expansions as to the correlation length of a weakly correlated random process which is used in the excitation model. As the main result...

  1. Dynamic Correlation in Wave Propagation in Random Media

    OpenAIRE

    Chabanov, A. A.; Hu, B.; Genack, A. Z.

    2004-01-01

    We report time-resolved measurements of the statistics of pulsed transmission through quasi-one-dimensional dielectric media with static disorder. The normalized intensity correlation function with displacement and polarization rotation for an incident pulse of linewidth $\\sigma$ at delay time t is a function only of the field correlation function, which is identical to that found for steady-state excitation, and of $\\kappa_{\\sigma}(t)$, the residual degree of intensity correlation at points ...

  2. Auto-correlation Properties of Scattering Light in Ultrasound-modulated Random Media

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiqin; XING Da; LIU Ying; MA Shining

    2001-01-01

    In this paper, the auto-correlation properties of scattering light in random media modulated by ultrasound were studied. The expression of temporal auto-correlation function of scattering light amplitude in the ultrasound-modulated media was presented. The results show that the auto-correlation function is modulated as the ultrasound is introduced into the media and the modulation amplitude decays with correlation time. The influences of ultrasound amplitude, Brownian diffusion coefficient, scattering and absorption coefficients on auto-correlation function were discussed. The auto-correlation imaging of an object hidden in random media was also studied by the use of Monte Carlo simulations.

  3. Spatial quantum correlations induced by random multiple scattering of quadrature squeezed light

    DEFF Research Database (Denmark)

    Lodahl, Peter

    The authors demonstrates that spatial quantum correlations are induced by multiple scattering of quadrature squeezed light through a random medium. As a consequence, light scattered along two different directions by the random medium will not be independent, but be correlated to an extent that can...... only be described by a quantum mechanical theory for multiple scattering. The spatial quantum correlation is revealed in the fluctuations of the total intensity transmission or reflection through the multiple scattering medium....

  4. Bimodal mesoporous silica with bottleneck pores.

    Science.gov (United States)

    Reber, M J; Brühwiler, D

    2015-11-01

    Bimodal mesoporous silica consisting of two sets of well-defined mesopores is synthesized by a partial pseudomorphic transformation of an ordered mesoporous starting material (SBA-15 type). The introduction of a second set of smaller mesopores (MCM-41 type) establishes a pore system with bottlenecks that restricts the access to the core of the bimodal mesoporous silica particles. The particle size and shape of the starting material are retained, but micropores present in the starting material disappear during the transformation, leading to a true bimodal mesoporous product. A varying degree of transformation allows the adjustment of the pore volume contribution of the two mesopore domains. Information on the accessibility of the mesopores is obtained by the adsorption of fluorescence-labeled poly(amidoamine) dendrimers and imaging by confocal laser scanning microscopy. This information is correlated with nitrogen sorption data to provide insights regarding the spatial distribution of the two mesopore domains. The bimodal mesoporous materials are excellent model systems for the investigation of cavitation effects in nitrogen desorption isotherms. PMID:26399172

  5. Resolving particle size modality in bi-modal iron oxide nanoparticle suspensions

    International Nuclear Information System (INIS)

    Particle size modality in bi-modal iron oxide suspensions was resolved by exploiting complex ac-susceptibility (ACS), small angle X-ray scattering (SAXS) and photon cross-correlation spectroscopy. To explain dynamic magnetic response of bi-modal suspensions, the Debye model was expanded to a linear superposition form allowing for the contribution of both particle fractions. This modified and adopted model is able to resolve the bi-modal particle size distributions. The SAXS curves of mono- and bi-modal suspensions were fitted well using a Monte Carlo simulation scheme, allowing the detection of bi-modal particle size distributions with high precision

  6. Diffusion tensor visualization using random field correlation and volume rendering

    OpenAIRE

    Sigfridsson, Andreas; Estepar, R.; Wigström, Lars; Alberola, C; Westin, C-F

    2003-01-01

    The visualization of diffusion tensor fields remains a challenging topic. A representation based on volume rendering of a scalar field is presented. The method uses the tensor to correlate a noise field in the direction of greater diffusivity while preserving the high frequency components of the noise field in transversal diffusion directions.

  7. Exponential Decay of Correlations for Randomly Chosen Hyperbolic Toral Automorphisms

    OpenAIRE

    Ayyer, Arvind; Stenlund, Mikko

    2007-01-01

    We consider pairs of toral automorphisms (A,B) satisfying an invariant cone property. At each iteration, A acts with probability p and B with probability 1-p. We prove exponential decay of correlations for a class of Holder continuous observables.

  8. Fluctuations and Correlations of Emission from Random Lasers

    CERN Document Server

    Merrill, Jason W; Dufresne, Eric R

    2015-01-01

    When light travels through strongly scattering media with optical gain, the synergy between diffusive transport and stimulated emission can lead to lasing action. Below the threshold pump power, the emission spectrum is smooth and consistent from shot-to-shot. Above the lasing threshold, the spectrum of emitted light becomes spiky and shows strong fluctuations from shot-to-shot. Recent experiments have reported that emitted intensity resembles a power-law distribution (\\emph{i.e.} L\\'evy statistics). Recent theories have described the emergence of L\\'evy statistics as an intrinsic property of lasing in random media. To separate intrinsic intensity fluctuations from the motion of scatterers, we compare the statistics of samples with stationary or freely-diffusing scatterers. Consistent with previous reports, we observe L\\'evy-like statistics when intensity data are pooled across an ensemble of scatterer configurations. For fixed scatterers, we find exponential intensity distributions whose mean intensities var...

  9. Random Sampling of Correlated Parameters – a Consistent Solution for Unfavourable Conditions

    International Nuclear Information System (INIS)

    Two methods for random sampling according to a multivariate lognormal distribution – the correlated sampling method and the method of transformation of correlation coefficients – are briefly presented. The methods are mathematically exact and enable consistent sampling of correlated inherently positive parameters with given information on the first two distribution moments. Furthermore, a weighted sampling method to accelerate the convergence of parameters with extremely large relative uncertainties is described. However, the method is efficient only for a limited number of correlated parameters

  10. 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.

  11. Efficient generation of correlated random numbers using Chebyshev-optimal magnitude-only IIR filters

    CERN Document Server

    Rodríguez, A; Johnson, Steven G.; Rodriguez, Alejandro

    2007-01-01

    We compare several methods for the efficient generation of correlated random sequences (colored noise) by filtering white noise to achieve a desired correlation spectrum. We argue that a class of IIR filter-design techniques developed in the 1970s, which obtain the global Chebyshev-optimum minimum-phase filter with a desired magnitude and arbitrary phase, are uniquely suited for this problem but have seldom been used. The short filters that result from such techniques are crucial for applications of colored noise in physical simulations involving random processes, for which many long random sequences must be generated and computational time and memory are at a premium.

  12. A study of randomness, correlations, and collectivity in the nuclear shell model

    International Nuclear Information System (INIS)

    A variable combination of realistic and random two-body interactions allows the study of collective properties [such as the energy spectra and B(E2) transition strengths] in 44Ti, 48Cr, and 24Mg. It is found that the average energies of the yrast band states maintain the ordering for any degree of randomness, but the B(E2) values lose their quadrupole collectivity when randomness dominates the Hamiltonian. The high probability of the yrast band to be ordered in the presence of pure random forces exhibits the strong correlations between the different members of the band

  13. Central limit theorem for a class of globally correlated random variables

    Science.gov (United States)

    Budini, Adrián A.

    2016-06-01

    The standard central limit theorem with a Gaussian attractor for the sum of independent random variables may lose its validity in the presence of strong correlations between the added random contributions. Here, we study this problem for similar interchangeable globally correlated random variables. Under these conditions, a hierarchical set of equations is derived for the conditional transition probabilities. This result allows us to define different classes of memory mechanisms that depend on a symmetric way on all involved variables. Depending on the correlation mechanisms and statistics of the single variables, the corresponding sums are characterized by distinct probability densities. For a class of urn models it is also possible to characterize their domain of attraction, which, as in the standard case, is parametrized by the probability density of each random variable. Symmetric and asymmetric q -Gaussian attractors (q <1 ) arise in a particular two-state case of these urn models.

  14. a Path-Integration Approach to the Correlators of XY Heisenberg Magnet and Random Walks

    Science.gov (United States)

    Bogoliubov, N. M.; Malyshev, C.

    2008-11-01

    The path integral approach is used for the calculation of the correlation functions of the XY Heisenberg chain. The obtained answers for the two-point correlators of the XX magnet are of the determinantal form and are interpreted in terms of the generating functions for the random turns vicious walkers.

  15. Detecting bimodality in astronomical datasets

    Science.gov (United States)

    Ashman, Keith A.; Bird, Christina M.; Zepf, Stephen E.

    1994-01-01

    We discuss statistical techniques for detecting and quantifying bimodality in astronomical datasets. We concentrate on the KMM algorithm, which estimates the statistical significance of bimodality in such datasets and objectively partitions data into subpopulations. By simulating bimodal distributions with a range of properties we investigate the sensitivity of KMM to datasets with varying characteristics. Our results facilitate the planning of optimal observing strategies for systems where bimodality is suspected. Mixture-modeling algorithms similar to the KMM algorithm have been used in previous studies to partition the stellar population of the Milky Way into subsystems. We illustrate the broad applicability of KMM by analyzing published data on globular cluster metallicity distributions, velocity distributions of galaxies in clusters, and burst durations of gamma-ray sources. FORTRAN code for the KMM algorithm and directions for its use are available from the authors upon request.

  16. Detecting bimodality in astronomical datasets

    CERN Document Server

    Ashman, K M; Zepf, S E; Keith M Ashman; Christina M Bird; Steven E Zepf

    1994-01-01

    We discuss statistical techniques for detecting and quantifying bimodality in astronomical datasets. We concentrate on the KMM algorithm, which estimates the statistical significance of bimodality in such datasets and objectively partitions data into sub-populations. By simulating bimodal distributions with a range of properties we investigate the sensitivity of KMM to datasets with varying characteristics. Our results facilitate the planning of optimal observing strategies for systems where bimodality is suspected. Mixture-modeling algorithms similar to the KMM algorithm have been used in previous studies to partition the stellar population of the Milky Way into subsystems. We illustrate the broad applicability of KMM by analysing published data on globular cluster metallicity distributions, velocity distributions of galaxies in clusters, and burst durations of gamma-ray sources. PostScript versions of the tables and figures, as well as FORTRAN code for KMM and instructions for its use, are available by anon...

  17. Intracluster correlation coefficients in cluster randomized trials: empirical insights into how should they be reported.

    OpenAIRE

    Grimshaw Jeremy M; Campbell Marion K; Elbourne Diana R

    2004-01-01

    Abstract Background Increasingly, researchers are recognizing that there are many situations where the use of a cluster randomized trial may be more appropriate than an individually randomized trial. Similarly, the need for appropriate standards of reporting of cluster trials is more widely acknowledged. Methods In this paper, we describe the results of a survey to inform the appropriate reporting of the intracluster correlation coefficient (ICC) – the statistical measure of the clustering ef...

  18. Damped Rabi wavepacket oscillations and damping time in correlated random ladders

    Science.gov (United States)

    Caetano, R. A.; Lyra, M. L.; Schulz, P. A.

    2013-12-01

    In this work, we follow the time evolution of an initially localized one-electron wavepacket in a random ladder model with correlated diagonal disorder. Weak localization of the eigenstates is anticipated for antisymmetric cross-correlations with every base pair having the same average energy. We show that the wavepacket width develops damped Rabi-like oscillations after reaching the ladder's borders. The Rabi-like oscillations are shown to originate from the interference between neighboring energy eigenstates, while its damping is associated with a destructive interference due to the random scattering in the underlying random potential. The typical damping time td is estimated as a function of the ladder size N and shown to increase as td∝Nz with z=0.62(4). The strong localization in the absence of antisymmetric cross-correlations suppresses the oscillations.

  19. Parity effects in eigenvalue correlators, parametric and crossover correlators in random matrix models: Application to mesoscopic systems

    Indian Academy of Sciences (India)

    N Deo

    2002-02-01

    This paper summarizes some work that I have been doing on eigenvalue correlators of random matrix models which show some interesting behavior. First we consider matrix models with gaps in their spectrum or density of eigenvalues. The density–density correlators of these models depend on whether , where is the size of the matrix, takes even or odd values. The fact that this dependence persists in the large thermodynamic limit is an unusual property and may have consequences in the study of one electron effects in mesoscopic systems. Secondly, we study the parametric and cross correlators of the Harish Chandra–Itzykson–Zuber matrix model. The analytic expressions determine how the correlators change as a parameter (e.g. the strength of a perturbation in the Hamiltonian of the chaotic system or external magnetic field on a sample of material) is varied. The results are relevant for the conductance fluctuations in disordered mesoscopic systems.

  20. Renormalisation group calculation of correlation functions for the 2D random bond Ising and Potts models

    CERN Document Server

    Dotsenko, V S; Pujol, P; Dotsenko, Vladimir; Picco, Marco; Pujol, Pierre

    1995-01-01

    We find the cross-over behavior for the spin-spin correlation function for the 2D Ising and 3-states Potts model with random bonds at the critical point. The procedure employed is the renormalisation approach of the perturbation series around the conformal field theories representing the pure models. We obtain a crossover in the amplitude for the correlation function for the Ising model which doesn't change the critical exponent, and a shift in the critical exponent produced by randomness in the case of the Potts model. A comparison with numerical data is discussed briefly.

  1. Efficient generation of correlated random numbers using Chebyshev-optimal magnitude-only IIR filters

    OpenAIRE

    Rodriguez, Alejandro; Johnson, Steven G.

    2007-01-01

    We compare several methods for the efficient generation of correlated random sequences (colored noise) by filtering white noise to achieve a desired correlation spectrum. We argue that a class of IIR filter-design techniques developed in the 1970s, which obtain the global Chebyshev-optimum minimum-phase filter with a desired magnitude and arbitrary phase, are uniquely suited for this problem but have seldom been used. The short filters that result from such techniques are crucial for applicat...

  2. Bimodal stimulus timing-dependent plasticity in primary auditory cortex is altered after noise exposure with and without tinnitus.

    Science.gov (United States)

    Basura, Gregory J; Koehler, Seth D; Shore, Susan E

    2015-12-01

    Central auditory circuits are influenced by the somatosensory system, a relationship that may underlie tinnitus generation. In the guinea pig dorsal cochlear nucleus (DCN), pairing spinal trigeminal nucleus (Sp5) stimulation with tones at specific intervals and orders facilitated or suppressed subsequent tone-evoked neural responses, reflecting spike timing-dependent plasticity (STDP). Furthermore, after noise-induced tinnitus, bimodal responses in DCN were shifted from Hebbian to anti-Hebbian timing rules with less discrete temporal windows, suggesting a role for bimodal plasticity in tinnitus. Here, we aimed to determine if multisensory STDP principles like those in DCN also exist in primary auditory cortex (A1), and whether they change following noise-induced tinnitus. Tone-evoked and spontaneous neural responses were recorded before and 15 min after bimodal stimulation in which the intervals and orders of auditory-somatosensory stimuli were randomized. Tone-evoked and spontaneous firing rates were influenced by the interval and order of the bimodal stimuli, and in sham-controls Hebbian-like timing rules predominated as was seen in DCN. In noise-exposed animals with and without tinnitus, timing rules shifted away from those found in sham-controls to more anti-Hebbian rules. Only those animals with evidence of tinnitus showed increased spontaneous firing rates, a purported neurophysiological correlate of tinnitus in A1. Together, these findings suggest that bimodal plasticity is also evident in A1 following noise damage and may have implications for tinnitus generation and therapeutic intervention across the central auditory circuit. PMID:26289461

  3. Quaternion determinant expressions for multilevel dynamical correlation functions of parametric random matrices

    International Nuclear Information System (INIS)

    Parametric random matrix ensembles which describe the transition among different matrix symmetries are studied. In the case of the transition to the hermitian symmetry, exact expressions for dynamical correlation functions among many eigenvalues at different times are shown to have quaternion determinant forms

  4. 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.

  5. Quaternion determinant expressions for multilevel dynamical correlation functions of parametric random matrices

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Taro; Forrester, Peter J

    1999-12-20

    Parametric random matrix ensembles which describe the transition among different matrix symmetries are studied. In the case of the transition to the hermitian symmetry, exact expressions for dynamical correlation functions among many eigenvalues at different times are shown to have quaternion determinant forms.

  6. Extending the random-phase approximation for electronic correlation energies: the renormalized adiabatic local density approximation

    DEFF Research Database (Denmark)

    Olsen, Thomas; Thygesen, Kristian S.

    2012-01-01

    The adiabatic connection fluctuation-dissipation theorem with the random phase approximation (RPA) has recently been applied with success to obtain correlation energies of a variety of chemical and solid state systems. The main merit of this approach is the improved description of dispersive forces...

  7. Random matrix theory analysis of cross-correlations in the US stock market: Evidence from Pearson’s correlation coefficient and detrended cross-correlation coefficient

    Science.gov (United States)

    Wang, Gang-Jin; Xie, Chi; Chen, Shou; Yang, Jiao-Jiao; Yang, Ming-Yan

    2013-09-01

    In this study, we first build two empirical cross-correlation matrices in the US stock market by two different methods, namely the Pearson’s correlation coefficient and the detrended cross-correlation coefficient (DCCA coefficient). Then, combining the two matrices with the method of random matrix theory (RMT), we mainly investigate the statistical properties of cross-correlations in the US stock market. We choose the daily closing prices of 462 constituent stocks of S&P 500 index as the research objects and select the sample data from January 3, 2005 to August 31, 2012. In the empirical analysis, we examine the statistical properties of cross-correlation coefficients, the distribution of eigenvalues, the distribution of eigenvector components, and the inverse participation ratio. From the two methods, we find some new results of the cross-correlations in the US stock market in our study, which are different from the conclusions reached by previous studies. The empirical cross-correlation matrices constructed by the DCCA coefficient show several interesting properties at different time scales in the US stock market, which are useful to the risk management and optimal portfolio selection, especially to the diversity of the asset portfolio. It will be an interesting and meaningful work to find the theoretical eigenvalue distribution of a completely random matrix R for the DCCA coefficient because it does not obey the Marčenko-Pastur distribution.

  8. To be and not to be: scale correlations in random multifractal processes

    DEFF Research Database (Denmark)

    Cleve, Jochen; Schmiegel, Jürgen; Greiner, Martin

    We discuss various properties of a random multifractal process, which are related to the issue of scale correlations. By design, the process is homogeneous, non-conservative and has no built-in scale correlations. However, when it comes to observables like breakdown coefficients, which are based on...... a coarse-graining of the multifractal field, scale correlations do appear. In the log-normal limit of the model process, the conditional distributions and moments of breakdown coefficients reproduce the observations made in fully developed small-scale turbulence. These findings help to understand...

  9. Investigation of correlation characteristics for random array collaborative beamforming using noise signals

    Science.gov (United States)

    Alexander, David B.; Narayanan, Ram M.; Himed, Braham

    2016-05-01

    The performance of different random array geometries is analyzed and compared. Three phased array geometries are considered: linear arrays with non-uniform randomized spacing between elements, circular arrays with non-uniform element radii, and ad hoc sensor networks with elements located randomly within a circular area. For each of these array geometries, computer simulations modeled the transmission, reflection from an arbitrary target, and reception of signals. The effectiveness of each array's beamforming techniques was measured by taking the peak cross-correlation between the received signal and a time-delayed replica of the original transmitted signal. For each array type, the correlation performance was obtained for transmission and reception of both chirp waveforms and ultra-wideband noise signals. It was found that the non-uniform linear array generally produced the highest correlation between transmitted and reflected signals. The non-uniform circular and ad hoc arrays demonstrated the most consistent performance with respect to noise signal bandwidth. The effect of scan angle was found to have a significant impact on the correlation performance of the linear arrays, where the correlation performance declines as the scan angle moves away from broadside to the array.

  10. Experimental Characterization of Correlation-Functions of Random Surfaces by Speckle Measurement and Complementary Algorithm

    Institute of Scientific and Technical Information of China (English)

    程传福; 刘曼; 滕树云; 宋洪胜; 陈建平; 徐至展

    2003-01-01

    A method for the extracting the correlation functions of random surfaces is proposed by using the image speckle intensity. Theoretically, we analyse the integral expression of average intensity of the image speckles, and compare it with the pair of Fourier-Bessel-transform-and-the-inversion of the exponential function of the height-height correlation function of the random surfaces. Then the algorithm is proposed numerically to complement the lacking Bessel function factor in the expression of the average speckle intensity, which changes the intensity data into the pair of the Fourier-Bessel-transform. Experimentally, we measure the average image speckle intensities versus the radius of the filtering aperture in the 4 f system and extract the height-height correlation function by using the proposed algorithm. The results of the practical measurements for three surface samples and the comparison with those by atomic force microscopy validate the feasibility of this method.

  11. A supersymmetry approach to billiards with randomly distributed scatterers: II. Correlations

    International Nuclear Information System (INIS)

    In a previous contribution (Stoeckmann H J 2002 J. Phys. A: Math. Gen. 35 5165), the density of states was calculated for a billiard with randomly distributed delta-like scatterers, doubly averaged over the positions of the impurities and the billiard shape. This result is now extended to the k-point correlation function. Using supersymmetric methods, we show that the correlations in the bulk are always identical to those of the Gaussian unitary ensemble (GUE) of random matrices. In passing from the band centre to the tail states, the density of states is depleted considerably and the two-point correlation function shows a gradual change from the GUE behaviour to that found for completely uncorrelated eigenvalues. This can be viewed as similar to a mobility edge

  12. Degree-correlation, omniscience, and randomized immunization protocols in finite networks

    CERN Document Server

    Alm, Jeremy F

    2016-01-01

    Many naturally occurring networks have a power-law degree distribution as well as a non-zero degree correlation. Despite this, most studies analyzing the efficiency of immunization strategies in networks have concentrated only on power-law degree distribution and ignored degree correlation. This study looks specifically at the effect degree-correlation has on the efficiency of several immunization strategies in scale-free networks. Generally, we found that positive degree correlation raises the number of immunized individuals needed to stop the spread of the infection. Importantly, we found that in networks with positive degree correlation, immunization strategies that utilize knowledge of initial popularity actually perform worse on average than random immunization strategies.

  13. Random number generation deficits in patients with multiple sclerosis: Characteristics and neural correlates.

    Science.gov (United States)

    Geisseler, Olivia; Pflugshaupt, Tobias; Buchmann, Andreas; Bezzola, Ladina; Reuter, Katja; Schuknecht, Bernhard; Weller, David; Linnebank, Michael; Brugger, Peter

    2016-09-01

    Human subjects typically deviate systematically from randomness when attempting to produce a sequence of random numbers. Despite an increasing number of behavioral and functional neuroimaging studies on random number generation (RNG), its structural correlates have never been investigated. We set out to fill this gap in 44 patients with multiple sclerosis (MS), a disease whose impact on RNG has never been studied. The RNG task required the paced (1 Hz) generation of the numbers from 1 to 6 in a sequence as random as possible. The same task was administered in 39 matched healthy controls. To assess neuroanatomical correlates such as cortical thickness, lesion load and third ventricle width, all subjects underwent high-resolution structural MRI. Compared to controls, MS patients exhibited an enhanced tendency to arrange consecutive numbers in an ascending order ("forward counting"). Furthermore, patients showed a higher susceptibility to rule breaks (producing out-of-category digits like 7) and to skip beats of the metronome. Clinico-anatomical correlation analyses revealed two main findings: First, increased counting in MS patients was associated with higher cortical lesion load. Second, increased number of skipped beats was related to widespread cortical thinning. In conclusion, our test results illustrate a loss of behavioral complexity in the course of MS, while the imaging results suggest an association between this loss and cortical pathology. PMID:27403852

  14. Dynamics of bimodality in vehicular traffic flows

    OpenAIRE

    Mullick, Arjun; Ray, Arnab K.

    2012-01-01

    A model equation has been proposed to describe bimodal features in vehicular traffic flows. The dynamics of the bimodal distribution reveals the existence of a fixed point that is connected to itself by a homoclinic trajectory. The mathematical conditions associated with bimodality have been established. The critical factors necessary for both a breaking of symmetry and a transition from bimodal to unimodal behaviour, in the manner of a bifurcation, have been analysed.

  15. Statistics of time delay and scattering correlation functions in chaotic systems. I. Random matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Novaes, Marcel [Instituto de Física, Universidade Federal de Uberlândia, Ave. João Naves de Ávila, 2121, Uberlândia, MG 38408-100 (Brazil)

    2015-06-15

    We consider the statistics of time delay in a chaotic cavity having M open channels, in the absence of time-reversal invariance. In the random matrix theory approach, we compute the average value of polynomial functions of the time delay matrix Q = − iħS{sup †}dS/dE, where S is the scattering matrix. Our results do not assume M to be large. In a companion paper, we develop a semiclassical approximation to S-matrix correlation functions, from which the statistics of Q can also be derived. Together, these papers contribute to establishing the conjectured equivalence between the random matrix and the semiclassical approaches.

  16. Statistics of time delay and scattering correlation functions in chaotic systems. I. Random matrix theory

    International Nuclear Information System (INIS)

    We consider the statistics of time delay in a chaotic cavity having M open channels, in the absence of time-reversal invariance. In the random matrix theory approach, we compute the average value of polynomial functions of the time delay matrix Q = − iħS†dS/dE, where S is the scattering matrix. Our results do not assume M to be large. In a companion paper, we develop a semiclassical approximation to S-matrix correlation functions, from which the statistics of Q can also be derived. Together, these papers contribute to establishing the conjectured equivalence between the random matrix and the semiclassical approaches

  17. Visualisation and characterisation of heterogeneous bimodal PDMS networks

    DEFF Research Database (Denmark)

    Bahrt, Frederikke; Daugaard, Anders Egede; Fleury, Clemence;

    2014-01-01

    The existence of short-chain domains in heterogeneous bimodal PDMS networks has been confirmed visually, for the first time, through confocal fluorescence microscopy. The networks were prepared using a controlled reaction scheme where short PDMS chains were reacted below the gelation point into...... bimodal networks with short-chain domains within a long-chain network. The average sizes of the short-chain domains were found to vary from 2.1 to 5.7 mm depending on the short-chain content. The visualised network structure could be correlated thereafter to the elastic properties, which were determined...... by rheology. All heterogeneous bimodal networks displayed significantly lower moduli than mono-modal PDMS elastomers prepared from the long polymer chains. Low-loss moduli as well as low-sol fractions indicate that low-elastic moduli can be obtained without compromising the network's structure...

  18. Correlated biased random walk with latency in one and two dimensions: Asserting patterned and unpredictable movement

    Science.gov (United States)

    Rodriguez-Horta, E.; Estevez-Rams, E.; Lora-Serrano, R.; Fernández, B. Aragón

    2016-09-01

    The correlated biased random walk with latency in one and two dimensions is discussed with regard to the portion of irreducible random movement and structured movement. It is shown how a quantitative analysis can be carried out by using computational mechanics. The stochastic matrix for both dynamics are reported. Latency introduces new states in the finite state machine description of the system in both dimensions, allowing for a full nearest neighbor coordination in the two dimensional case. Complexity analysis is used to characterize the movement, independently of the set of control parameters, making it suitable for the discussion of other random walk models. The complexity map of the system dynamics is reported for the two dimensional case.

  19. Dielectric matrix formulation of correlation energies in the Random Phase Approximation (RPA): inclusion of exchange effects

    CERN Document Server

    Mussard, Bastien; Jansen, Georg; Angyan, Janos

    2016-01-01

    Starting from the general expression for the ground state correlation energy in the adiabatic connection fluctuation dissipation theorem (ACFDT) framework, it is shown that the dielectric matrix formulation, which is usually applied to calculate the direct random phase approximation (dRPA) correlation energy, can be used for alternative RPA expressions including exchange effects. Within this famework, the ACFDT analog of the second order screened exchange (SOSEX) approximation leads to a logarithmic formula for the correlation energy similar to the direct RPA expression. Alternatively, the contribution of the exchange can be included in the kernel used to evaluate the response functions. In this case the use of an approximate kernel is crucial to simplify the formalism and to obtain a correlation energy in logarithmic form. Technical details of the implementation of these methods are discussed and it is shown that one can take advantage of density fitting or Cholesky decomposition techniques to improve the co...

  20. Effects of 3D random correlated velocity perturbations on predicted ground motions

    Science.gov (United States)

    Hartzell, S.; Harmsen, S.; Frankel, A.

    2010-01-01

    Three-dimensional, finite-difference simulations of a realistic finite-fault rupture on the southern Hayward fault are used to evaluate the effects of random, correlated velocity perturbations on predicted ground motions. Velocity perturbations are added to a three-dimensional (3D) regional seismic velocity model of the San Francisco Bay Area using a 3D von Karman random medium. Velocity correlation lengths of 5 and 10 km and standard deviations in the velocity of 5% and 10% are considered. The results show that significant deviations in predicted ground velocities are seen in the calculated frequency range (≤1 Hz) for standard deviations in velocity of 5% to 10%. These results have implications for the practical limits on the accuracy of scenario ground-motion calculations and on retrieval of source parameters using higher-frequency, strong-motion data.

  1. Distribution Versus Correlation Induced Anomalous Transport in Quenched Random Velocity Fields

    OpenAIRE

    Dentz, Marco; Bolster, Diogo

    2010-01-01

    We study mechanisms of anomalous transport in quenched random media. Broad disorder point distributions and strong disorder correlations cause anomalous transport and can lead to the same anomalous scaling laws for the mean and variance of the particle displacements. The respective mechanisms, however, are fundamentally different. This difference is reflected in the spatial particle densities and first passage time distributions, which provide an indicator to identify the origins of anomalous...

  2. Correlated Random Systems Five Different Methods : CIRM Jean-Morlet Chair

    CERN Document Server

    Kistler, Nicola

    2015-01-01

    This volume presents five different methods recently developed to tackle the large scale behavior of highly correlated random systems, such as spin glasses, random polymers, local times and loop soups and random matrices. These methods, presented in a series of lectures delivered within the Jean-Morlet initiative (Spring 2013), play a fundamental role in the current development of probability theory and statistical mechanics. The lectures were: Random Polymers by E. Bolthausen, Spontaneous Replica Symmetry Breaking and Interpolation Methods by F. Guerra, Derrida's Random Energy Models by N. Kistler, Isomorphism Theorems by J. Rosen and Spectral Properties of Wigner Matrices by B. Schlein. This book is the first in a co-edition between the Jean-Morlet Chair at CIRM and the Springer Lecture Notes in Mathematics which aims to collect together courses and lectures on cutting-edge subjects given during the term of the Jean-Morlet Chair, as well as new material produced in its wake. It is targeted at researchers, i...

  3. On the Correlation Functions of the Characteristic Polynomials of the Sparse Hermitian Random Matrices

    Science.gov (United States)

    Afanasiev, Ie.

    2016-04-01

    We consider asymptotics of the correlation functions of characteristic polynomials corresponding to random weighted G(n, p/n) Erdős-Rényi graphs with Gaussian weights in the case of finite p and also when p rightarrow infty . It is shown that for finite p the second correlation function demonstrates a kind of transition: when p 2 there appears an interval (-λ _*(p), λ _*(p)) such that for λ _0 in (-λ _*(p), λ _*(p)) the second correlation function behaves like that for Gaussian unitary ensemble (GUE), while for λ _0 outside the interval the second correlation function is still factorized. For p rightarrow infty there is also a threshold in the behavior of the second correlation function near λ _0 = ± 2: for p ≪ n^{2/3} the second correlation function factorizes, whereas for p ≫ n^{2/3} it behaves like that for GUE. For any rate of p rightarrow infty the asymptotics of correlation functions of any even order for λ _0 in (-2, 2) coincide with that for GUE.

  4. A bimodal biometric identification system

    Science.gov (United States)

    Laghari, Mohammad S.; Khuwaja, Gulzar A.

    2013-03-01

    Biometrics consists of methods for uniquely recognizing humans based upon one or more intrinsic physical or behavioral traits. Physicals are related to the shape of the body. Behavioral are related to the behavior of a person. However, biometric authentication systems suffer from imprecision and difficulty in person recognition due to a number of reasons and no single biometrics is expected to effectively satisfy the requirements of all verification and/or identification applications. Bimodal biometric systems are expected to be more reliable due to the presence of two pieces of evidence and also be able to meet the severe performance requirements imposed by various applications. This paper presents a neural network based bimodal biometric identification system by using human face and handwritten signature features.

  5. Oculomotor interference of bimodal distractors

    OpenAIRE

    Heeman, Jessica; Nijboer, Tanja C. W.; van der Stoep, Nathan; Theeuwes, Jan; Stigchel, Stefan Van der

    2016-01-01

    When executing an eye movement to a target location, the presence of an irrelevant distracting stimulus can influence the saccade metrics and latency. The present study investigated the influence of distractors of different sensory modalities (i.e. auditory, visual and audiovisual) which were presented at various distances (i.e. close or remote) from a visual target. The interfering effects of a bimodal distractor were more pronounced in the spatial domain than in the temporal domain. The res...

  6. Parametric spectral statistics in unitary random matrix ensembles: from distribution functions to intra-level correlations

    International Nuclear Information System (INIS)

    We establish a general framework to explore parametric statistics of individual energy levels in unitary random matrix ensembles. For a generic confinement potential Tr W(H), we (i) find the joint distribution functions of the eigenvalues of H and H' = H + V for an arbitrary fixed V both for finite matrix size N and in the 'thermodynamic' N → ∞ limit; (ii) derive many-point parametric correlation functions of the two sets of eigenvalues and show that they are naturally parametrized by the eigenvalues of the reactance matrix for scattering off the 'potential' V; (iii) prove the universality of the correlation functions in unitary ensembles with non-Gaussian non-invariant confinement potential Tr W(H - V); (iv) establish a general scheme for exact calculation of level-number-dependent parametric correlation functions and apply the scheme to the calculation of intra-level velocity autocorrelation function and the distribution of parametric level shifts

  7. Intensity correlations in random media induced by refractive index tuning (RIT)

    CERN Document Server

    Faez, Sanli; Lagendijk, Ad

    2009-01-01

    We introduce a new approach for measuring both the transport and the effective medium properties of light propagation in inhomogeneous media. These properties include the diffusion constant, the path length distribution, and the effective index of refraction. Our method utilizes the equivalence of frequency variation with a change in the index of refraction. A new correlation function that describes correlations in both frequency and index of refraction is introduced. Experimentally, we measure this correlation via spectrally resolved refractive index tuning (RIT), controlling the latter via changes in the ambient pressure. Our new generic measurement technique can be used to characterize a wide variety of materials, including photonic crystals, random photonic media, photonic meta-materials, and certain porous biological samples like bone and wood.

  8. Wigner–Racah Algebra, Binary Correlations and Trace Propagation for Embedded Random Matrix Ensembles

    International Nuclear Information System (INIS)

    For embedded unitary ensembles with SU(Ω) × SU(r) embedding and generated by random two-body (in some situations k-body) interactions preserving SU(r) symmetry, analytical formulas, in terms of SU(Ω) Racah coefficients, are derived for the lower order moments of the one and two-point functions in eigenvalues. This formulation unifies all known results and new results are derived for r = 3. Similarly, the method of binary correlation approximation developed for spinless identical fermion systems, has been extended to proton-neutron systems and it is used to show that the bivariate transition strength density appropriate for neutrinoless double beta decay will be close to a bivariate Gaussian. In addition, trace propagation methods of French are also used to derive analytical results for embedded ensembles and they have opened a new window to understand regular structures generated by random interactions.

  9. Exclusive many-particle diffusion in disordered media and correlation functions for random vertex models

    International Nuclear Information System (INIS)

    We consider systems of particles hopping stochastically on d-dimensional lattices with space-dependent probabilities. We map the master equation in a Fock space where the dynamics are given by a quantum Hamiltonian (continuous time) or a transfer matrix resp. (discrete time). We show that under certain conditions the time-dependent two-point density correlation function in N-particle steady state can be computed from the probability distribution of a single particle moving in the same environment. Focussing on exclusion models where the lattice site can be occupied by at most one particle we discuss as an example for such a stochastic process a generalized Heisenberg antiferromagnet where the strength of the spin-spin coupling in space-dependent. In discrete time one obtains for one dimensional systems the diagonal-to-diagonal transfer matrix of the two dimensional six vertex model with space dependent vertex weights. For a random distribution of the vertex weights one obtains a version of the random barrier model describing diffusion of particles in disordered media. We derive exact expressions for the average two-point density correlation function in the presence of weak, correlated disorder. (authors)

  10. Bond percolation on a class of correlated and clustered random graphs

    International Nuclear Information System (INIS)

    We introduce a formalism for computing bond percolation properties of a class of correlated and clustered random graphs. This class of graphs is a generalization of the configuration model where nodes of different types are connected via different types of hyperedges, edges that can link more than two nodes. We argue that the multitype approach coupled with the use of clustered hyperedges can reproduce a wide spectrum of complex patterns, and thus enhances our capability to model real complex networks. As an illustration of this claim, we use our formalism to highlight unusual behaviours of the size and composition of the components (small and giant) in a synthetic, albeit realistic, social network. (paper)

  11. Parametric Spectral Statistics in Unitary Random Matrix Ensembles: From Distribution Functions to Intra-Level Correlations

    OpenAIRE

    Smolyarenko, I. E.; Simons, B D

    2003-01-01

    We establish a general framework to explore parametric statistics of individual energy levels in unitary random matrix ensembles. For a generic confinement potential $W(H)$, we (i) find the joint distribution functions of the eigenvalues of $H$ and $H'=H+V$ for an arbitrary fixed $V$ both for finite matrix size $N$ and in the ``thermodynamic'' $N\\to\\infty$ limit; (ii) derive many-point parametric correlation functions of the two sets of eigenvalues and show that they are naturally parametrise...

  12. Reliability analysis of multi-degree-of-freedom nonlinear random structure vibration systems with correlation failure modes

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Yimin; (张义民); WANG; Shun; (王; 顺); LIU; Qiaoling; (刘巧伶); WEN; Bangchun; (闻邦椿)

    2003-01-01

    Based on the generalized probabilistic finite element method, this paper presents an approximate solution technique for general multi-degree-of-freedom nonlinear random vibration systems with random parameters. The fourth-moment technique, maximum entropy theory and incomplete probability information theory are employed to systematically develop a reliability analysis method for dynamic random structural systems with correlation failure modes under unavailable joint probability density functions of basic random variables. The first passage problem of multi-degree-of-freedom nonlinear random vibration systems is solved.

  13. Bimodal gene expression patterns in breast cancer

    OpenAIRE

    Nikolsky Yuri; Bugrim Andrej; Shi Weiwei; Kirillov Eugene; Bessarabova Marina; Nikolskaya Tatiana

    2010-01-01

    Abstract We identified a set of genes with an unexpected bimodal distribution among breast cancer patients in multiple studies. The property of bimodality seems to be common, as these genes were found on multiple microarray platforms and in studies with different end-points and patient cohorts. Bimodal genes tend to cluster into small groups of four to six genes with synchronised expression within the group (but not between the groups), which makes them good candidates for robust conditional ...

  14. Performance Sampling and Bimodal Duration Dependence

    OpenAIRE

    Jerker Denrell; Zur Shapira

    2006-01-01

    Performance sampling models of duration dependence in employee turnover and firm exit predict that hazard rates will initially be low, gradually rise to a maximum, and then fall. As we note in this paper, however, several empirical duration distributions have bimodal hazard rates. This paper shows that such bimodal hazard rates can be derived from existing models of performance sampling by small changes in the assumptions. In particular, bimodal hazard rates emerge if the mean or the variance...

  15. MAGNETIC DYNAMO ACTION IN RANDOM FLOWS WITH ZERO AND FINITE CORRELATION TIMES

    International Nuclear Information System (INIS)

    Hydromagnetic dynamo theory provides the prevailing theoretical description for the origin of magnetic fields in the universe. Here, we consider the problem of kinematic, small-scale dynamo action driven by a random, incompressible, non-helical, homogeneous, and isotropic flow. In the Kazantsev dynamo model, the statistics of the driving flow are assumed to be instantaneously correlated in time. Here, we compare the results of the model with the dynamo properties of a simulated flow that has similar spatial characteristics as the Kazantsev flow but different temporal statistics. In particular, the simulated flow is a solution of the forced Navier-Stokes equations and hence has a finite correlation time. We find that the Kazantsev model typically predicts a larger magnetic growth rate and a magnetic spectrum that peaks at smaller scales. However, we show that by filtering the diffusivity spectrum at small scales it is possible to bring the growth rates into agreement and simultaneously align the magnetic spectra.

  16. Probability distributions for directed polymers in random media with correlated noise.

    Science.gov (United States)

    Chu, Sherry; Kardar, Mehran

    2016-07-01

    The probability distribution for the free energy of directed polymers in random media (DPRM) with uncorrelated noise in d=1+1 dimensions satisfies the Tracy-Widom distribution. We inquire if and how this universal distribution is modified in the presence of spatially correlated noise. The width of the distribution scales as the DPRM length to an exponent β, in good (but not full) agreement with previous renormalization group and numerical results. The scaled probability is well described by the Tracy-Widom form for uncorrelated noise, but becomes symmetric with increasing correlation exponent. We thus find a class of distributions that continuously interpolates between Tracy-Widom and Gaussian forms. PMID:27575059

  17. Intracluster correlation coefficients in cluster randomized trials: empirical insights into how should they be reported

    Directory of Open Access Journals (Sweden)

    Grimshaw Jeremy M

    2004-04-01

    Full Text Available Abstract Background Increasingly, researchers are recognizing that there are many situations where the use of a cluster randomized trial may be more appropriate than an individually randomized trial. Similarly, the need for appropriate standards of reporting of cluster trials is more widely acknowledged. Methods In this paper, we describe the results of a survey to inform the appropriate reporting of the intracluster correlation coefficient (ICC – the statistical measure of the clustering effect associated with a cluster randomized trial. Results We identified three dimensions that should be considered when reporting an ICC – a description of the dataset (including characteristics of the outcome and the intervention, information on how the ICC was calculated, and information on the precision of the ICC. Conclusions This paper demonstrates the development of a framework for the reporting of ICCs. If adopted into routine practice, it has the potential to facilitate the interpretation of the cluster trial being reported and should help the development of new trials in the area.

  18. Neural correlates of cognitive improvements following cognitive remediation in schizophrenia: a systematic review of randomized trials

    Directory of Open Access Journals (Sweden)

    Clémence Isaac

    2016-03-01

    Full Text Available Background: Cognitive impairments are a core feature in schizophrenia and are linked to poor social functioning. Numerous studies have shown that cognitive remediation can enhance cognitive and functional abilities in patients with this pathology. The underlying mechanism of these behavioral improvements seems to be related to structural and functional changes in the brain. However, studies on neural correlates of such enhancement remain scarce. Objectives: We explored the neural correlates of cognitive enhancement following cognitive remediation interventions in schizophrenia and the differential effect between cognitive training and other therapeutic interventions or patients’ usual care. Method: We searched MEDLINE, PsycInfo, and ScienceDirect databases for studies on cognitive remediation therapy in schizophrenia that used neuroimaging techniques and a randomized design. Search terms included randomized controlled trial, cognitive remediation, cognitive training, rehabilitation, magnetic resonance imaging, positron emission tomography, electroencephalography, magnetoencephalography, near infrared spectroscopy, and diffusion tensor imaging. We selected randomized controlled trials that proposed multiple sessions of cognitive training to adult patients with a schizophrenia spectrum disorder and assessed its efficacy with imaging techniques. Results: In total, 15 reports involving 19 studies were included in the systematic review. They involved a total of 455 adult patients, 271 of whom received cognitive remediation. Cognitive remediation therapy seems to provide a neurobiological enhancing effect in schizophrenia. After therapy, increased activations are observed in various brain regions mainly in frontal – especially prefrontal – and also in occipital and anterior cingulate regions during working memory and executive tasks. Several studies provide evidence of an improved functional connectivity after cognitive training, suggesting a

  19. The two-point correlation function of randomly distributed Lyman alpha clouds

    Science.gov (United States)

    Fardal, Mark A.; Shull, J. Michael

    1993-01-01

    It is often assumed that Ly-alpha forest clouds are randomly distributed, intergalactic objects that are highly ionized by the UV background produced by quasars. If these assumptions are true, fluctuations in the UV background should produce a nonzero two point correlation function in the Ly-alpha forest. This effect, which is really just a generalization of the proximity effect, is more significant at high redshift (z is approximately 3-4) because the mean free path for UV photons is smaller there, and the fluctuations correspondingly larger. This effect was studied using both the semi-analytic techniques of Zuo's recent papers and Monte Carlo simulations. The correlation function is expected to have a small yet potentially measurable amplitude that is consistent with current upper limits. Furthermore, the signature of this effect is distinctive because the nonzero correlation function extends over the photon mean free path, which is larger than the expected scale of large-scale structure. Observations or upper limits on this effect could provide information about the source of the ionizing background at high redshifts and the nature of the Ly-alpha forest clouds.

  20. Miniversal Deformations of Bimodal Picewise Linear Systems

    OpenAIRE

    Ferrer Llop, Josep; Magret Planas, Maria dels Dolors; Pacha Andújar, Juan Ramón; Peña Carrera, Marta

    2010-01-01

    Keywords: Bimodal piecewise linear system, miniversal deformations, reduced forms. Bimodal linear systems are those consisting of two linear systems on each side of a given hyperplane, having continuous dynamics along that hyperplane. In this work, we focus on the derivation of (orthogonal) miniversal deformations, by using reduced forms.

  1. BSA adsorption on bimodal PEO brushes

    NARCIS (Netherlands)

    Bosker, W.T.E.; Iakovlev, P.A.; Norde, W.; Cohen Stuart, M.A.

    2005-01-01

    BSA adsorption onto bimodal PEO brushes at a solid surface was measured using optical reflectometry. Bimodal brushes consist of long (N=770) and short (N=48) PEO chains and were prepared on PS surfaces, applying mixtures of PS 29-PEO48 and PS37-PEO770 block copolymers and using the Langmuir-Blodgett

  2. BSA adsorption on bimodal PEO brushes

    NARCIS (Netherlands)

    Bosker, WTE; Iakovlev, PA; Norde, W; Stuart, MAC

    2005-01-01

    BSA adsorption onto bimodal PEO brushes at a solid surface was measured using optical reflectometry. Bimodal brushes consist of long (N = 770) and short (N = 48) PEO chains and were prepared on PS surfaces, applying mixtures of PS29-PEO48 and PS37-PEO770 block copolymers and using the Langmuir-Blodg

  3. Non-random aneuploidy specifies subgroups of pilocytic astrocytoma and correlates with older age.

    Science.gov (United States)

    Fontebasso, Adam M; Shirinian, Margret; Khuong-Quang, Dong-Anh; Bechet, Denise; Gayden, Tenzin; Kool, Marcel; De Jay, Nicolas; Jacob, Karine; Gerges, Noha; Hutter, Barbara; Şeker-Cin, Huriye; Witt, Hendrik; Montpetit, Alexandre; Brunet, Sébastien; Lepage, Pierre; Bourret, Geneviève; Klekner, Almos; Bognár, László; Hauser, Peter; Garami, Miklós; Farmer, Jean-Pierre; Montes, Jose-Luis; Atkinson, Jeffrey; Lambert, Sally; Kwan, Tony; Korshunov, Andrey; Tabori, Uri; Collins, V Peter; Albrecht, Steffen; Faury, Damien; Pfister, Stefan M; Paulus, Werner; Hasselblatt, Martin; Jones, David T W; Jabado, Nada

    2015-10-13

    Pilocytic astrocytoma (PA) is the most common brain tumor in children but is rare in adults, and hence poorly studied in this age group. We investigated 222 PA and report increased aneuploidy in older patients. Aneuploid genomes were identified in 45% of adult compared with 17% of pediatric PA. Gains were non-random, favoring chromosomes 5, 7, 6 and 11 in order of frequency, and preferentially affecting non-cerebellar PA and tumors with BRAF V600E mutations and not with KIAA1549-BRAF fusions or FGFR1 mutations. Aneuploid PA differentially expressed genes involved in CNS development, the unfolded protein response, and regulators of genomic stability and the cell cycle (MDM2, PLK2),whose correlated programs were overexpressed specifically in aneuploid PA compared to other glial tumors. Thus, convergence of pathways affecting the cell cycle and genomic stability may favor aneuploidy in PA, possibly representing an additional molecular driver in older patients with this brain tumor. PMID:26378811

  4. Random phase approximation correlation energy using a compact representation for linear response functions: application to solids

    International Nuclear Information System (INIS)

    A new approach was recently presented to compute correlation energies within the random phase approximation using Lanczos chains and an optimal basis set (Rocca 2014 J. Chem. Phys. 140 18A501). This novel method avoids the explicit calculation of conduction states and represents linear response functions on a compact auxiliary basis set obtained from the diagonalization of an approximate dielectric matrix that contains only the kinetic energy contribution. Here, we extend this formalism, originally implemented for molecular systems, to treat periodic solids. In particular, the approximate dielectric matrix used to build the auxiliary basis set is generalized to avoid unphysical negative gaps, that make the model inefficient. The numerical convergence of the method is discussed and the accuracy is demonstrated considering a set including three covalently bonded (C, Si, and SiC) and three weakly bonded (Ne, Ar, and Kr) solids. (paper)

  5. Random matrix approach to group correlations in development country financial market

    Science.gov (United States)

    Qohar, Ulin Nuha Abdul; Lim, Kyuseong; Kim, Soo Yong; Liong, The Houw; Purqon, Acep

    2015-12-01

    Financial market is a borderless economic activity, everyone in this world has the right to participate in stock transactions. The movement of stocks is interesting to be discussed in various sciences, ranging from economists to mathe-maticians try to explain and predict the stock movement. Econophysics, as a discipline that studies the economic behavior using one of the methods in particle physics to explain stock movement. Stocks tend to be unpredictable probabilistic regarded as a probabilistic particle. Random Matrix Theory is one method used to analyze probabilistic particle is used to analyze the characteristics of the movement in the stock collection of developing country stock market shares of the correlation matrix. To obtain the characteristics of the developing country stock market and use characteristics of stock markets of developed countries as a parameter for comparison. The result shows market wide effect is not happened in Philipine market and weak in Indonesia market. Contrary, developed country (US) has strong market wide effect.

  6. Exchange-correlation energy from pairing matrix fluctuation and the particle-particle random phase approximation

    International Nuclear Information System (INIS)

    Despite their unmatched success for many applications, commonly used local, semi-local, and hybrid density functionals still face challenges when it comes to describing long-range interactions, static correlation, and electron delocalization. Density functionals of both the occupied and virtual orbitals are able to address these problems. The particle-hole (ph-) Random Phase Approximation (RPA), a functional of occupied and virtual orbitals, has recently known a revival within the density functional theory community. Following up on an idea introduced in our recent communication [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013)], we formulate more general adiabatic connections for the correlation energy in terms of pairing matrix fluctuations described by the particle-particle (pp-) propagator. With numerical examples of the pp-RPA, the lowest-order approximation to the pp-propagator, we illustrate the potential of density functional approximations based on pairing matrix fluctuations. The pp-RPA is size-extensive, self-interaction free, fully anti-symmetric, describes the strong static correlation limit in H2, and eliminates delocalization errors in H2+ and other single-bond systems. It gives surprisingly good non-bonded interaction energies – competitive with the ph-RPA – with the correct R−6 asymptotic decay as a function of the separation R, which we argue is mainly attributable to its correct second-order energy term. While the pp-RPA tends to underestimate absolute correlation energies, it gives good relative energies: much better atomization energies than the ph-RPA, as it has no tendency to underbind, and reaction energies of similar quality. The adiabatic connection in terms of pairing matrix fluctuation paves the way for promising new density functional approximations

  7. Exchange-correlation energy from pairing matrix fluctuation and the particle-particle random phase approximation

    Energy Technology Data Exchange (ETDEWEB)

    Aggelen, Helen van [Department of Inorganic and Physical Chemistry, Ghent University, Ghent (Belgium); Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Yang, Yang [Department of Chemistry, Duke University, Durham, North Carolina 27708 (United States); Yang, Weitao [Department of Chemistry and Department of Physics, Duke University, Durham, North Carolina 27708 (United States)

    2014-05-14

    Despite their unmatched success for many applications, commonly used local, semi-local, and hybrid density functionals still face challenges when it comes to describing long-range interactions, static correlation, and electron delocalization. Density functionals of both the occupied and virtual orbitals are able to address these problems. The particle-hole (ph-) Random Phase Approximation (RPA), a functional of occupied and virtual orbitals, has recently known a revival within the density functional theory community. Following up on an idea introduced in our recent communication [H. van Aggelen, Y. Yang, and W. Yang, Phys. Rev. A 88, 030501 (2013)], we formulate more general adiabatic connections for the correlation energy in terms of pairing matrix fluctuations described by the particle-particle (pp-) propagator. With numerical examples of the pp-RPA, the lowest-order approximation to the pp-propagator, we illustrate the potential of density functional approximations based on pairing matrix fluctuations. The pp-RPA is size-extensive, self-interaction free, fully anti-symmetric, describes the strong static correlation limit in H{sub 2}, and eliminates delocalization errors in H{sub 2}{sup +} and other single-bond systems. It gives surprisingly good non-bonded interaction energies – competitive with the ph-RPA – with the correct R{sup −6} asymptotic decay as a function of the separation R, which we argue is mainly attributable to its correct second-order energy term. While the pp-RPA tends to underestimate absolute correlation energies, it gives good relative energies: much better atomization energies than the ph-RPA, as it has no tendency to underbind, and reaction energies of similar quality. The adiabatic connection in terms of pairing matrix fluctuation paves the way for promising new density functional approximations.

  8. Exploiting SNP correlations within random forest for genome-wide association studies.

    Directory of Open Access Journals (Sweden)

    Vincent Botta

    Full Text Available The primary goal of genome-wide association studies (GWAS is to discover variants that could lead, in isolation or in combination, to a particular trait or disease. Standard approaches to GWAS, however, are usually based on univariate hypothesis tests and therefore can account neither for correlations due to linkage disequilibrium nor for combinations of several markers. To discover and leverage such potential multivariate interactions, we propose in this work an extension of the Random Forest algorithm tailored for structured GWAS data. In terms of risk prediction, we show empirically on several GWAS datasets that the proposed T-Trees method significantly outperforms both the original Random Forest algorithm and standard linear models, thereby suggesting the actual existence of multivariate non-linear effects due to the combinations of several SNPs. We also demonstrate that variable importances as derived from our method can help identify relevant loci. Finally, we highlight the strong impact that quality control procedures may have, both in terms of predictive power and loci identification. Variable importance results and T-Trees source code are all available at www.montefiore.ulg.ac.be/~botta/ttrees/ and github.com/0asa/TTree-source respectively.

  9. Efficient design of cluster randomized and multicentre trials with unknown intraclass correlation.

    Science.gov (United States)

    van Breukelen, Gerard J P; Candel, Math J J M

    2015-10-01

    For cluster randomized and multicentre trials evaluating the effect of a treatment on persons nested within clusters, equations have been published to compute the optimal sample sizes at the cluster and person level as a function of sampling costs and intraclass correlation (ICC). Here, optimal means maximum power and precision for a given sampling budget, or minimum sampling costs for a given power and precision. However, the ICC is usually unknown, and the optimal sample sizes depend strongly on this ICC. To overcome this local optimality problem, this study presents Maximin designs (MMDs) based on relative efficiency (RE) and efficiency. These designs perform well over a range of possible ICC values either in terms of RE compared with the locally optimal designs, or in terms of minimum efficiency (maximum variance) of the treatment effect estimator. The use of MMDs is illustrated using information from many cluster randomized trials in primary care. It is concluded that MMDs and the optimal design for an ICC halfway its assumed range are efficient for a range of ICC values and recommendable for practical use. This requires that trial reports mention the study cost per cluster and person. PMID:21937473

  10. The shape of invasion percolation clusters in random and correlated media

    International Nuclear Information System (INIS)

    The shape of two-dimensional invasion percolation clusters are studied numerically for both non-trapping (NTIP) and trapping (TIP) invasion percolation processes. Two different anisotropy quantifiers, the anisotropy parameter and the asphericity, are used for probing the degree of anisotropy of clusters. We observe that, in spite of the difference in scaling properties of NTIP and TIP, there is no difference in the values of anisotropy quantifiers of these processes. Furthermore, we find that, in completely random media, the invasion percolation clusters are on average slightly less isotropic than standard percolation clusters. Introducing isotropic long-range correlations into the media reduces the isotropy of the invasion percolation clusters. The effect is more pronounced for the case of persisting long-range correlations. The implication of boundary conditions on the shape of clusters is another subject of interest. Compared to the case of free boundary conditions, IP clusters of conventional rectangular geometry turn out to be more isotropic. Moreover, we see that in conventional rectangular geometry the NTIP clusters are more isotropic than the TIP clusters

  11. Two-dimensional structure from random multiparticle X-ray scattering images using cross-correlations

    Science.gov (United States)

    Pedrini, B.; Menzel, A.; Guizar-Sicairos, M.; Guzenko, V. A.; Gorelick, S.; David, C.; Patterson, B. D.; Abela, R.

    2013-04-01

    Knowledge of the structure of biological macromolecules, especially in their native environment, is crucial because of the close structure-function relationship. X-ray small-angle scattering is used to determine the shape of particles in solution, but the achievable resolution is limited owing to averaging over particle orientations. In 1977, Kam proposed to obtain additional structural information from the cross-correlation of the scattering intensities. Here we develop the method in two dimensions, and give a procedure by which the single-particle diffraction pattern is extracted in a model-independent way from the correlations. We demonstrate its application to a large set of synchrotron X-ray scattering images on ensembles of identical, randomly oriented particles of 350 or 200 nm in size. The obtained 15 nm resolution in the reconstructed shape is independent of the number of scatterers. The results are discussed in view of proposed ‘snapshot’ scattering by molecules in the liquid phase at X-ray free-electron lasers.

  12. Radiation propagation in random media: From positive to negative correlations in high-frequency fluctuations

    International Nuclear Information System (INIS)

    We survey research on radiation propagation or ballistic particle motion through media with randomly variable material density, and we investigate the topic with an emphasis on very high spatial frequencies. Our new results are based on a specific variability model consisting of a zero-mean Gaussian scaling noise riding on a constant value that is large enough with respect to the amplitude of the noise to yield overwhelmingly non-negative density. We first generalize known results about sub-exponential transmission from regular functions, which are almost everywhere continuous, to merely 'measurable' ones, which are almost everywhere discontinuous (akin to statistically stationary noises), with positively correlated fluctuations. We then use the generalized measure-theoretic formulation to address negatively correlated stochastic media without leaving the framework of conventional (continuum-limit) transport theory. We thus resolve a controversy about recent claims that only discrete-point process approaches can accommodate negative correlations, i.e., anti-clustering of the material particles. We obtain in this case the predicted super-exponential behavior, but it is rather weak. Physically, and much like the alternative discrete-point process approach, the new model applies most naturally to scales commensurate with the inter-particle distance in the material, i.e., when the notion of particle density breaks down due to Poissonian-or maybe not-so-Poissonian-number-count fluctuations occur in the sample volume. At the same time, the noisy structure must prevail up to scales commensurate with the mean-free-path to be of practical significance. Possible applications are discussed.

  13. Radiation transport through random media represented as measurable functions: Positive versus negative spatial correlations

    International Nuclear Information System (INIS)

    We investigate particle transport through media with randomly variable material properties with a special emphasis on very high spatial frequencies. In multi-dimensional transport theory, particularly in computational studies, collision coefficients are assumed to be 'functions' in the conventional sense of the word: they have specific values at every point in the medium. This assumption actually constrains spatial variability in the high-frequency range in a manner that is not a mathematical necessity and relaxing it opens the door to interesting transport physics. From the standpoint of the integral transport equation, coefficient variations in space can indeed be represented as 'measures,' i.e., mathematical constructs that only make numerical sense under an integral (in the sense of Lebesgue). The new results are based on a variability model consisting of a zero-mean Gaussian scaling noise riding on a constant value large enough with respect to the amplitude of the noise to yield overwhelmingly non-negative coefficients; technically, this represents a 'measurable' function. We first generalize known results about sub-exponential transmission from regular (almost everywhere continuous) to merely measurable functions with positively- correlated fluctuations. Another interesting outcome is that, in this very general measure-based framework, one can use conventional (continuum-limit) transport theory to address negatively- as well as positively-correlated stochastic media. We thus resolve a controversy concerning recent claims that only discrete-point process approaches can accommodate negative correlations, i.e., anti-clustering of the obstructing material particles. We obtain in this case the predicted super-exponential behavior, but only over a limited range of transport distances. (authors)

  14. The price of privately releasing contingency tables, and the spectra of random matrices with correlated rows

    Energy Technology Data Exchange (ETDEWEB)

    Kasiviswanathan, Shiva [Los Alamos National Laboratory; Rudelson, Mark [UNIV OF MISSOURI; Smith, Adam [PENNSYLVANIA STATE U

    2009-01-01

    Contingency tables are the method of choice of government agencies for releasing statistical summaries of categorical data. In this paper, we consider lower bounds on how much distortion (noise) is necessary in these tables to provide privacy guarantees when the data being summarized is sensitive. We extend a line of recent work on lower bounds on noise for private data analysis [10, 13. 14, 15] to a natural and important class of functionalities. Our investigation also leads to new results on the spectra of random matrices with correlated rows. Consider a database D consisting of n rows (one per individual), each row comprising d binary attributes. For any subset of T attributes of size |T| = k, the marginal table for T has 2{sup k} entries; each entry counts how many times in the database a particular setting of these attributes occurs. Imagine an agency that wishes to release all (d/k) contingency tables for a given database. For constant k, previous work showed that distortion {tilde {Omicron}}(min{l_brace}n, (n{sup 2}d){sup 1/3}, {radical}d{sup k}{r_brace}) is sufficient for satisfying differential privacy, a rigorous definition of privacy that has received extensive recent study. Our main contributions are: (1) For {epsilon}- and ({epsilon}, {delta})-differential privacy (with {epsilon} constant and {delta} = 1/poly(n)), we give a lower bound of {tilde {Omega}}(min{l_brace}{radical}n, {radical}d{sup k}{r_brace}), which is tight for n = {tilde {Omega}}(d{sup k}). Moreover, for a natural and popular class of mechanisms based on additive noise, our bound can be strengthened to {Omega}({radical}d{sup k}), which is tight for all n. Our bounds extend even to non-constant k, losing roughly a factor of {radical}2{sup k} compared to the best known upper bounds for large n. (2) We give efficient polynomial time attacks which allow an adversary to reconstruct sensitive infonnation given insufficiently perturbed contingency table releases. For constant k, we obtain a

  15. Intraclass correlation coefficients for cluster randomized trials in care pathways and usual care: hospital treatment for heart failure

    OpenAIRE

    Kul, Seval; Vanhaecht, Kris; Panella, Massimiliano

    2014-01-01

    Background Cluster randomized trials are increasingly being used in healthcare evaluation to show the effectiveness of a specific intervention. Care pathways (CPs) are becoming a popular tool to improve the quality of health-care services provided to heart failure patients. In order to perform a well-designed cluster randomized trial to demonstrate the effectiveness of Usual care (UC) and CP in heart failure treatment, the intraclass correlation coefficient (ICC) should be available before co...

  16. Scalable statistics of correlated random variables and extremes applied to deep borehole porosities

    Science.gov (United States)

    Guadagnini, A.; Neuman, S. P.; Nan, T.; Riva, M.; Winter, C. L.

    2015-02-01

    We analyze scale-dependent statistics of correlated random hydrogeological variables and their extremes using neutron porosity data from six deep boreholes, in three diverse depositional environments, as example. We show that key statistics of porosity increments behave and scale in manners typical of many earth and environmental (as well as other) variables. These scaling behaviors include a tendency of increments to have symmetric, non-Gaussian frequency distributions characterized by heavy tails that decay with separation distance or lag; power-law scaling of sample structure functions (statistical moments of absolute increments) in midranges of lags; linear relationships between log structure functions of successive orders at all lags, known as extended self-similarity or ESS; and nonlinear scaling of structure function power-law exponents with function order, a phenomenon commonly attributed in the literature to multifractals. Elsewhere we proposed, explored and demonstrated a new method of geostatistical inference that captures all of these phenomena within a unified theoretical framework. The framework views data as samples from random fields constituting scale mixtures of truncated (monofractal) fractional Brownian motion (tfBm) or fractional Gaussian noise (tfGn). Important questions not addressed in previous studies concern the distribution and statistical scaling of extreme incremental values. Of special interest in hydrology (and many other areas) are statistics of absolute increments exceeding given thresholds, known as peaks over threshold or POTs. In this paper we explore the statistical scaling of data and, for the first time, corresponding POTs associated with samples from scale mixtures of tfBm or tfGn. We demonstrate that porosity data we analyze possess properties of such samples and thus follow the theory we proposed. The porosity data are of additional value in revealing a remarkable cross-over from one scaling regime to another at certain

  17. Sequence correction of random coil chemical shifts: correlation between neighbor correction factors and changes in the Ramachandran distribution

    DEFF Research Database (Denmark)

    Kjærgaard, Magnus; Poulsen, Flemming Martin

    2011-01-01

    this study, we use random coil peptides containing glutamine instead of glycine to determine the random coil chemical shifts and the neighbor correction factors. The resulting correction factors correlate to changes in the populations of the major wells in the Ramachandran plot, which demonstrates that...... changes in the conformational ensemble are an important source of neighbor effects in disordered proteins. Glutamine derived random coil chemical shifts and correction factors modestly improve our ability to predict (13)C chemical shifts of intrinsically disordered proteins compared to existing datasets......Random coil chemical shifts are necessary for secondary chemical shift analysis, which is the main NMR method for identification of secondary structure in proteins. One of the largest challenges in the determination of random coil chemical shifts is accounting for the effect of neighboring residues...

  18. Eigenvalue correlations and the distribution of ground state angular momenta for random many-body quantum systems

    International Nuclear Information System (INIS)

    The observed preponderance of ground states with angular momentum L=0 in many-body quantum systems with random two-body interactions is analyzed in terms of correlation coefficients (covariances) among different eigenstates. It is shown that the geometric analysis of Chau et al. can be interpreted in terms of correlations (covariances) between energy eigenvalues, thus providing an entirely statistical explanation of the distribution of ground state angular momenta of randomly interacting quantum systems that, in principle, is valid for both fermionic and bosonic systems. The method is illustrated for the interacting boson model.

  19. Spin-spin critical point correlation functions for the 2D random bond Ising and Potts models

    CERN Document Server

    Dotsenko, V S; Pujol, P; Vladimir Dotsenko; Marco Picco; Pierre Pujol

    1994-01-01

    We compute the combined two and three loop order correction to the spin-spin correlation functions for the 2D Ising and q-states Potts model with random bonds at the critical point. The procedure employed is the renormalisation group approach for the perturbation series around the conformal field theories representing the pure models. We obtain corrections for the correlations functions which produce crossover in the amplitude but don't change the critical exponent in the case of the Ising model and which produce a shift in the critical exponent, due to randomness, in the case of the Potts model. Comparison with numerical data is discussed briefly.

  20. Bimodal loop-gap resonator

    Science.gov (United States)

    Piasecki, W.; Froncisz, W.; Hyde, James S.

    1996-05-01

    A bimodal loop-gap resonator for use in electron paramagnetic resonance (EPR) spectroscopy at S band is described. It consists of two identical one-loop-one-gap resonators in coaxial juxtaposition. In one mode, the currents in the two loops are parallel and in the other antiparallel. By introducing additional capacitors between the loops, the frequencies of the two modes can be made to coincide. Details are given concerning variable coupling to each mode, tuning of the resonant frequency of one mode to that of the other, and adjustment of the isolation between modes. An equivalent circuit is given and network analysis carried out both experimentally and theoretically. EPR applications are described including (a) probing of the field distributions with DPPH, (b) continuous wave (cw) EPR with a spin-label line sample, (c) cw electron-electron double resonance (ELDOR), (d) modulation of saturation, and (e) saturation-recovery (SR) EPR. Bloch induction experiments can be performed when the sample extends half way through the structure, but microwave signals induced by Mx and My components of magnetization cancel when it extends completely through. This latter situation is particularly favorable for SR, modulation of saturation, and ELDOR experiments, which depend on observing Mz indirectly using a second weak observing microwave source.

  1. Irreducible complexity of iterated symmetric bimodal maps

    OpenAIRE

    Lampreia, J. P.; Severino, R.; J. Sousa Ramos

    2004-01-01

    We introduce a tree structure for the iterates of symmetric bimodal maps and identify a subset which we prove to be isomorphic to the family of unimodal maps. This subset is used as a second factor for a $\\ast $-product that we define in the space of bimodal kneading sequences. Finally, we give some properties for this product and study the *-product induced on the associated Markov shifts.

  2. A Note on Bimodal Accretion Disks

    OpenAIRE

    Dullemond, C.P.; Turolla, R.

    1998-01-01

    The existence of bimodal disks is investigated. Following a simple argument based on energetic considerations we show that stationary, bimodal accretion disk models in which a Shakura--Sunyaev disk (SSD) at large radii matches an advection dominated accretion flow (ADAF) at smaller radii are never possible using the standard slim disk approach, unless some extra energy flux is present. The same argument, however, predicts the possibility of a transition from an outer Shapiro--Lightman--Eardle...

  3. Irreducible complexity of iterated symmetric bimodal maps

    Directory of Open Access Journals (Sweden)

    J. P. Lampreia

    2005-01-01

    Full Text Available We introduce a tree structure for the iterates of symmetric bimodal maps and identify a subset which we prove to be isomorphic to the family of unimodal maps. This subset is used as a second factor for a ∗-product that we define in the space of bimodal kneading sequences. Finally, we give some properties for this product and study the ∗-product induced on the associated Markov shifts.

  4. Intraclass Correlations and Covariate Outcome Correlations for Planning 2 and 3 Level Cluster Randomized Experiments in Education

    Science.gov (United States)

    Hedges, Larry V.; Hedberg, Eric C.

    2013-01-01

    Background: Cluster randomized experiments that assign intact groups such as schools or school districts to treatment conditions are increasingly common in educational research. Such experiments are inherently multilevel designs whose sensitivity (statistical power and precision of estimates) depends on the variance decomposition across levels.…

  5. Intraclass Correlations and Covariate Outcome Correlations for Planning Two-and Three-Level Cluster-Randomized Experiments in Education

    Science.gov (United States)

    Hedges, Larry V.; Hedberg, E. C.

    2013-01-01

    Background: Cluster-randomized experiments that assign intact groups such as schools or school districts to treatment conditions are increasingly common in educational research. Such experiments are inherently multilevel designs whose sensitivity (statistical power and precision of estimates) depends on the variance decomposition across levels.…

  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. Random Responding as a Threat to the Validity of Effect Size Estimates in Correlational Research

    Science.gov (United States)

    Crede, Marcus

    2010-01-01

    Random responding to psychological inventories is a long-standing concern among clinical practitioners and researchers interested in interpreting idiographic data, but it is typically viewed as having only a minor impact on the statistical inferences drawn from nomothetic data. This article explores the impact of random responding on the size and…

  8. A minimalistic approach to static and dynamic electron correlations: Amending generalized valence bond method with extended random phase approximation correlation correction

    Science.gov (United States)

    Chatterjee, Koushik; Pastorczak, Ewa; Jawulski, Konrad; Pernal, Katarzyna

    2016-06-01

    A perfect-pairing generalized valence bond (GVB) approximation is known to be one of the simplest approximations, which allows one to capture the essence of static correlation in molecular systems. In spite of its attractive feature of being relatively computationally efficient, this approximation misses a large portion of dynamic correlation and does not offer sufficient accuracy to be generally useful for studying electronic structure of molecules. We propose to correct the GVB model and alleviate some of its deficiencies by amending it with the correlation energy correction derived from the recently formulated extended random phase approximation (ERPA). On the examples of systems of diverse electronic structures, we show that the resulting ERPA-GVB method greatly improves upon the GVB model. ERPA-GVB recovers most of the electron correlation and it yields energy barrier heights of excellent accuracy. Thanks to a balanced treatment of static and dynamic correlation, ERPA-GVB stays reliable when one moves from systems dominated by dynamic electron correlation to those for which the static correlation comes into play.

  9. Bimodal Nuclear Thermal Rocket Analysis Developments

    Science.gov (United States)

    Belair, Michael; Lavelle, Thomas; Saimento, Charles; Juhasz, Albert; Stewart, Mark

    2014-01-01

    Nuclear thermal propulsion has long been considered an enabling technology for human missions to Mars and beyond. One concept of operations for these missions utilizes the nuclear reactor to generate electrical power during coast phases, known as bimodal operation. This presentation focuses on the systems modeling and analysis efforts for a NERVA derived concept. The NERVA bimodal operation derives the thermal energy from the core tie tube elements. Recent analysis has shown potential temperature distributions in the tie tube elements that may limit the thermodynamic efficiency of the closed Brayton cycle used to generate electricity with the current design. The results of this analysis are discussed as well as the potential implications to a bimodal NERVA type reactor.

  10. Depth perception not found in human observers for static or dynamic anti-correlated random dot stereograms.

    Directory of Open Access Journals (Sweden)

    Paul B Hibbard

    Full Text Available One of the greatest challenges in visual neuroscience is that of linking neural activity with perceptual experience. In the case of binocular depth perception, important insights have been achieved through comparing neural responses and the perception of depth, for carefully selected stimuli. One of the most important types of stimulus that has been used here is the anti-correlated random dot stereogram (ACRDS. In these stimuli, the contrast polarity of one half of a stereoscopic image is reversed. While neurons in cortical area V1 respond reliably to the binocular disparities in ACRDS, they do not create a sensation of depth. This discrepancy has been used to argue that depth perception must rely on neural activity elsewhere in the brain. Currently, the psychophysical results on which this argument rests are not clear-cut. While it is generally assumed that ACRDS do not support the perception of depth, some studies have reported that some people, some of the time, perceive depth in some types of these stimuli. Given the importance of these results for understanding the neural correlates of stereopsis, we studied depth perception in ACRDS using a large number of observers, in order to provide an unambiguous conclusion about the extent to which these stimuli support the perception of depth. We presented observers with random dot stereograms in which correlated dots were presented in a surrounding annulus and correlated or anti-correlated dots were presented in a central circular region. While observers could reliably report the depth of the central region for correlated stimuli, we found no evidence for depth perception in static or dynamic anti-correlated stimuli. Confidence ratings for stereoscopic perception were uniformly low for anti-correlated stimuli, but showed normal variation with disparity for correlated stimuli. These results establish that the inability of observers to perceive depth in ACRDS is a robust phenomenon.

  11. Albumin to creatinine ratio in a random urine sample: Correlation with severity of preeclampsia

    Directory of Open Access Journals (Sweden)

    Fady S. Moiety

    2014-06-01

    Conclusions: Random urine ACR may be a reliable method for prediction and assessment of severity of preeclampsia. Using the estimated cut-off may add to the predictive value of such a simple quick test.

  12. Bimodality and negative heat capacity in multifragmentation

    International Nuclear Information System (INIS)

    This contribution addresses the question of the possible link between multifragmentation and the liquid-gas phase transition of nuclear matter. Bi-modality seems to be a robust signal of this link in the sense that theoretical calculations indicate that it is preserved even if a sizeable fraction of the available energy has not been shared among all the degrees of freedom. The corresponding measured properties are coherent with what is expected in a liquid-gas phase transition picture. Moreover, bi-modality and negative heat capacity are observed for the same set of events. (authors)

  13. Co-speech gesture in bimodal bilinguals

    OpenAIRE

    Casey, Shannon; Emmorey, Karen

    2008-01-01

    The effects of knowledge of sign language on co-speech gesture were investigated by comparing the spontaneous gestures of bimodal bilinguals (native users of American Sign Language and English; n = 13) and non-signing native English speakers (n = 12). Each participant viewed and re-told the Canary Row cartoon to a non-signer whom they did not know. Nine of the thirteen bimodal bilinguals produced at least one ASL sign, which we hypothesise resulted from a failure to inhibit ASL. Compared with...

  14. Periodicity in bimodal atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Chia-Yun; Santos, Sergio, E-mail: santos-en@yahoo.com; Chiesa, Matteo [Laboratory for Energy and NanoScience (LENS), Institute Center for Future Energy (iFES), Masdar Institute of Science and Technology, Abu Dhabi (United Arab Emirates); Barcons, Victor [Departament de Disseny i Programació de Sistemes Electrònics, UPC - Universitat Politècnica de Catalunya, Av. Bases, 61, 08242 Manresa (Barcelona) (Spain)

    2015-07-28

    Periodicity is fundamental for quantification and the application of conservation principles of many important systems. Here, we discuss periodicity in the context of bimodal atomic force microscopy (AFM). The relationship between the excited frequencies is shown to affect and control both experimental observables and the main expressions quantified via these observables, i.e., virial and energy transfer expressions, which form the basis of the bimodal AFM theory. The presence of a fundamental frequency further simplifies the theory and leads to close form solutions. Predictions are verified via numerical integration of the equation of motion and experimentally on a mica surface.

  15. Periodicity in bimodal atomic force microscopy

    International Nuclear Information System (INIS)

    Periodicity is fundamental for quantification and the application of conservation principles of many important systems. Here, we discuss periodicity in the context of bimodal atomic force microscopy (AFM). The relationship between the excited frequencies is shown to affect and control both experimental observables and the main expressions quantified via these observables, i.e., virial and energy transfer expressions, which form the basis of the bimodal AFM theory. The presence of a fundamental frequency further simplifies the theory and leads to close form solutions. Predictions are verified via numerical integration of the equation of motion and experimentally on a mica surface

  16. Bimodal condensation silicone elastomers as dielectric elastomers

    DEFF Research Database (Denmark)

    Yu, Liyun; Madsen, Frederikke Bahrt; Skov, Anne Ladegaard

    unimodal refers to that there is one polymer only in the system. As an alternative to unimodal networks there are the bimodal networks where two polymers with significantly different molecular weights are mixed with one crosslinker. [2]Silicone rubber can be divided into condensation type and addition type...... according to the curing reaction. The advantages of condensation silicones compared to addition are the relatively low cost, the curing rate largely being independent of temperature, the excellent adhesion, and the catalyst being nontoxic. [3]In this work, a series of bimodal condensation silicone...

  17. Exact solutions for social and biological contagion models on mixed directed and undirected, degree-correlated random networks

    CERN Document Server

    Payne, Joshua L; Dodds, Peter Sheridan

    2011-01-01

    We derive analytic expressions for the probability and expected size of global spreading events starting from a single infected seed for a broad collection of contagion processes acting on random networks with both directed and undirected edges and arbitrary degree-degree correlations. Our work extends previous theoretical developments for the undirected case, and we provide numerical support for our findings by investigating an example class of networks for which we are able to obtain closed-form expressions.

  18. Direct Numerical Simulation of Fracture Behaviour for Random Short Wood Fibres Reinforced Composites, Comparison with Digital Image Correlation Experiments

    Directory of Open Access Journals (Sweden)

    Brillaud J.

    2010-06-01

    Full Text Available The work is to predict fracture behaviour of bio-composites from the tensile properties of its components. In this work, we have realized a direct numerical simulation of fracture behaviour for random short spruce fibers reinforced composites. For calculations, wood fibers have been considered as linear elastic bodies, polypropylene matrix as an elastic-plastic material. Then, numerical results have been compared with experimental results that have been obtained by digital image correlation. This comparison indicates that random fiber FE model of random short spruce fibers reinforced composites can be able to fairly reflect the influence of random fibers microstructure in the composite on its fracture behavior. The calculation of both random fiber and homogeneous FE model and their comparison with experiments show that the average values of J-integral in a region in the front of the crack tip from both numerical FE models are in good agreement with the average J value of DIC experiment in the same region when the numerical and experimental CT specimens of the short spruce fiber reinforced composite are subjected to the same extension at their loading point.

  19. Orthogonal Polynomials and Exact Correlation Functions for Two Cut Random Matrix Models

    OpenAIRE

    Deo, Nivedita

    1997-01-01

    Exact eigenvalue correlation functions are computed for large $N$ hermitian one-matrix models with eigenvalues distributed in two symmetric cuts. An asymptotic form for orthogonal polynomials for arbitrary polynomial potentials that support a $Z_2$ symmetric distribution is obtained. This results in an exact explicit expression for the kernel at large $N$ which determines all eigenvalue correlators. The oscillating and smooth parts of the two point correlator are extracted and the universalit...

  20. Synchronization of the Kuramoto model on the complex networks with bimodal intrinsic frequency distribution

    Directory of Open Access Journals (Sweden)

    N Khodadoostan

    2014-11-01

    Full Text Available In this work, we study the Kuramoto model on scale-free, random and small-world networks with bimodal intrinsic frequency distributions. We consider two models: in one of them, the coupling constant of the ith oscillator is independent of the number of oscillators with which the oscillator interacts, and in the other one the coupling constant is renormalized with the number of oscillators with which the oscillator interacts. For the first model, the time which is required for reaching the stationary state is more than the time which is needed in the second one. Also, for both models the order parameter of the random and scale-free network decreases by increasing the intrinsic frequency with a bimodal distribution. Unlike scale-free and random networks, the order parameter of the small-world network increases by increasing the frequency at first. But later, it decreases and then starts to oscillate.

  1. Correlation Lengths for Random Polymer Models and for Some Renewal Sequences

    OpenAIRE

    Toninelli, F. L.

    2007-01-01

    We consider models of directed polymers interacting with a one-dimensional defect line on which random charges are placed. More abstractly, one starts from renewal sequence on $\\Z$ and gives a random (site-dependent) reward or penalty to the occurrence of a renewal at any given point of $\\mathbb Z$. These models are known to undergo a delocalization-localization transition, and the free energy $\\tf$ vanishes when the critical point is approached from the localized region. We prove that the qu...

  2. Deaf Children's Bimodal Bilingualism and Education

    Science.gov (United States)

    Swanwick, Ruth

    2016-01-01

    This paper provides an overview of the research into deaf children's bilingualism and bilingual education through a synthesis of studies published over the last 15 years. This review brings together the linguistic and pedagogical work on bimodal bilingualism to inform educational practice. The first section of the review provides a synthesis of…

  3. Controllability of Continuous Bimodal Linear Systems

    OpenAIRE

    Josep Ferrer; Juan R. Pacha; Marta Peña

    2013-01-01

    We consider bimodal linear systems consisting of two linear dynamics acting on each side of a given hyperplane, assuming continuity along the separating hyperplane. We prove that the study of controllability can be reduced to the unobservable case, and for these ones we obtain a simple explicit characterization of controllability for dimensions 2 and 3, as well as some partial criteria for higher dimensions.

  4. Bimodal Networks as Candidates for Electroactive Polymers

    DEFF Research Database (Denmark)

    Bahrt, Frederikke; Daugaard, Anders Egede; Bejenariu, Anca Gabriela;

    An alternative network formulation method was adopted in order to obtain a different type of silicone based elastomeric systems - the so-called bimodal networks - using two vinyl-terminated polydimethyl siloxanes (PDMS) of different molecular weight, a labelled crosslinker (3 or 4-functional), and...

  5. An optimum approximation of n-point correlation functions of random heterogeneous material systems

    Science.gov (United States)

    Baniassadi, M.; Safdari, M.; Garmestani, H.; Ahzi, S.; Geubelle, P. H.; Remond, Y.

    2014-02-01

    An approximate solution for n-point correlation functions is developed in this study. In the approximate solution, weight functions are used to connect subsets of (n-1)-point correlation functions to estimate the full set of n-point correlation functions. In previous related studies, simple weight functions were introduced for the approximation of three and four-point correlation functions. In this work, the general framework of the weight functions is extended and derived to achieve optimum accuracy for approximate n-point correlation functions. Such approximation can be utilized to construct global n-point correlation functions for a system when there exist limited information about these functions in a subset of space. To verify its accuracy, the new formulation is used to approximate numerically three-point correlation functions from the set of two-point functions directly evaluated from a virtually generated isotropic heterogeneous microstructure representing a particulate composite system. Similarly, three-point functions are approximated for an anisotropic glass fiber/epoxy composite system and compared to their corresponding reference values calculated from an experimental dataset acquired by computational tomography. Results from both virtual and experimental studies confirm the accuracy of the new approximation. The new formulation can be utilized to attain a more accurate approximation to global n-point correlation functions for heterogeneous material systems with a hierarchy of length scales.

  6. Shell model for time-correlated random advection of passive scalars

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Muratore-Ginanneschi, P.

    1999-01-01

    We study a minimal shell model for the advection of a passive scalar by a Gaussian time-correlated velocity field. The anomalous scaling properties of the white noise limit are studied analytically. The effect of the time correlations are investigated using perturbation theory around the white...

  7. Inhomogeneous Linear Random Differential Equations with Mutual Correlations between Multiplicative, Additive and Initial-Value Terms

    NARCIS (Netherlands)

    Roerdink, J.B.T.M.

    1981-01-01

    The cumulant expansion for linear stochastic differential equations is extended to the general case in which the coefficient matrix, the inhomogeneous part and the initial condition are all random and, moreover, statistically interdependent. The expansion now involves not only the autocorrelation fu

  8. Continuous-time random walk with correlated jumps on stock market

    International Nuclear Information System (INIS)

    Extension of the classical continuous-time random walk model created for description of share price evolution is presented. The model assumes that consecutive jumps are dependent; in this case it is exactly solvable, reconstructing, for example, the empirical velocity autocorrelation function (vacf). However, the problem of existing the fat tail in the nonlinear vacf is still an open one. (authors)

  9. Genetic and phenotypic correlations of quantitative traits in two long-term randomly mated soybean populations

    Science.gov (United States)

    The genetic effects of long term random mating and natural selection aided by genetic male sterility (gms) were evaluated in two soybean [Glycine max (L.) Merr.] populations designated: RSII and RSIII. These populations were evaluated in the field at three locations each with two replications. Genot...

  10. Bimodal and Gaussian Ising spin glasses in dimension two

    Science.gov (United States)

    Lundow, P. H.; Campbell, I. A.

    2016-02-01

    An analysis is given of numerical simulation data to size L =128 on the archetype square lattice Ising spin glasses (ISGs) with bimodal (±J ) and Gaussian interaction distributions. It is well established that the ordering temperature of both models is zero. The Gaussian model has a nondegenerate ground state and thus a critical exponent η ≡0 , and a continuous distribution of energy levels. For the bimodal model, above a size-dependent crossover temperature T*(L ) there is a regime of effectively continuous energy levels; below T*(L ) there is a distinct regime dominated by the highly degenerate ground state plus an energy gap to the excited states. T*(L ) tends to zero at very large L , leaving only the effectively continuous regime in the thermodynamic limit. The simulation data on both models are analyzed with the conventional scaling variable t =T and with a scaling variable τb=T2/(1 +T2) suitable for zero-temperature transition ISGs, together with appropriate scaling expressions. The data for the temperature dependence of the reduced susceptibility χ (τb,L ) and second moment correlation length ξ (τb,L ) in the thermodynamic limit regime are extrapolated to the τb=0 critical limit. The Gaussian critical exponent estimates from the simulations, η =0 and ν =3.55 (5 ) , are in full agreement with the well-established values in the literature. The bimodal critical exponents, estimated from the thermodynamic limit regime analyses using the same extrapolation protocols as for the Gaussian model, are η =0.20 (2 ) and ν =4.8 (3 ) , distinctly different from the Gaussian critical exponents.

  11. On Bimodal Offset Cauchy Distribution

    Directory of Open Access Journals (Sweden)

    Girija S.V.S.

    2013-05-01

    Full Text Available The bivariate Cauchy distribution has received applications in many areas, including biological analyses, clinical trials, stochastic modeling of decreasing failure rate life components, study of labour turnover, queuing theory and reliability (Nayak (1987 and Lee and Gross (1991. In the study of biological analyses, clinical trials and reliability circular distributions will yield suitable results. Circular data arises in a number of different areas such as geological, meteorological, biological and industrial sciences. It is not suggestive to use standard statistical techniques to model circular data, due to the circular geometry of the sample space (p.2 Jammalamadaka and Sen Gupta (2001. It is possible to construct a circular model by transforming a bivariate linear random variate to just its directional component and the resultant model is called ‘offset distribution’. In the literature most of the available circular models were constructed by wrapping a linear model. In recent years some wrapped models were constructed by Dattatreya Rao et al (2007. Here an attempt is made to exploit method of offsetting on Bivariate Cauchy distribution to construct a circular model named by us “OFFSET CAUCHY DISTRIBUTION (OC”. The characteristic function of the Offset Cauchy model is derived and its characteristics are discussed.

  12. Correlation functions of XX0 Heisenberg chain, q-binomial determinants, and random walks

    Energy Technology Data Exchange (ETDEWEB)

    Bogoliubov, N.M.; Malyshev, C.

    2014-02-15

    The XX0 Heisenberg model on a cyclic chain is considered. The representation of the Bethe wave functions via the Schur functions allows to apply the well-developed theory of the symmetric functions to the calculation of the thermal correlation functions. The determinantal expressions of the form-factors and of the thermal correlation functions are obtained. The q-binomial determinants enable the connection of the form-factors with the generating functions both of boxed plane partitions and of self-avoiding lattice paths. The asymptotical behavior of the thermal correlation functions is studied in the limit of low temperature provided that the characteristic parameters of the system are large enough.

  13. Correlation Functions of XX0 Heisenberg Chain, q-Binomial Determinants, and Random Walks

    CERN Document Server

    Bogoliubov, N M

    2014-01-01

    The XX0 Heisenberg model on a cyclic chain is considered. The representation of the Bethe wave functions via the Schur functions allows to apply the well-developed theory of the symmetric functions to the calculation of the thermal correlation functions. The determinantal expressions of the form-factors and of the thermal correlation functions are obtained. The q-binomial determinants enable the connection of the form-factors with the generating functions both of boxed plane partitions and of self-avoiding lattice paths. The asymptotical behavior of the thermal correlation functions is studied in the limit of low temperature provided that the characteristic parameters of the system are large enough.

  14. Correlation functions of XX0 Heisenberg chain, q-binomial determinants, and random walks

    Science.gov (United States)

    Bogoliubov, N. M.; Malyshev, C.

    2014-02-01

    The XX0 Heisenberg model on a cyclic chain is considered. The representation of the Bethe wave functions via the Schur functions allows to apply the well-developed theory of the symmetric functions to the calculation of the thermal correlation functions. The determinantal expressions of the form-factors and of the thermal correlation functions are obtained. The q-binomial determinants enable the connection of the form-factors with the generating functions both of boxed plane partitions and of self-avoiding lattice paths. The asymptotical behavior of the thermal correlation functions is studied in the limit of low temperature provided that the characteristic parameters of the system are large enough.

  15. Two-phase flow in correlated pore-throat random porous media

    Institute of Scientific and Technical Information of China (English)

    田巨平; 姚凯伦

    2002-01-01

    We have constructed a porous media model in which there are percolation clusters with varying percolation probability P and correlated site-bonds. Taking into account both the pore and the throat geometry, the viscous fingering (VF) in porous media has been investigated by using the standard over-relaxed Gauss-Seidel scheme. The simulation results show that the VF structure varies with the correlation parameter ε, the viscosity ratio M and the percolation probability P. The smaller the correlation parameter ε, the greater thedeviation of the normalized size distribution of the invaded throat Ninv(r) from the truncated Rayleigh distribution.For a larger viscosity ratio M,the VF pattern looks like a diffusion-limited-aggregation structure in percolation clusters. The fractal dimension D increases with the increase of the percolation probability P and the correlation parameter e. The velocity distribution f(α) of VF in percolation clusters is of a parabola-like curve. The tail of the distribution (large α) is longer for a larger correlation parameter ε. For a smaller ε, the distribution is very sharp. The sweep efficiency E decreases along with the decrease of the correlation parameter ε and the increase of the network size Lnz. E has a minimum as Lnz increases up to the maximum no matter what the values of P, M and ε. The E ~ Lnz curve has a frozen zone and an active zone. The geometry and the topology of the porous media have strong effects on the displacement processes and the structure of VF.

  16. Synthesis and Characterization of Bimodal Mesoporous Silica

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaofang; GUO Cuili; WANG Xiaoli; WU Yuanyuan

    2012-01-01

    Mesoporous silica with controllable bimodal pore size distribution was synthesized with cetyltrimethylammonium bromide (CTAB) as chemical template for small mesopores and silica gel as physical template for large mesopores.The structure of synthesized samples were characterized by Fourier transform infrared (FT-IR) spectroscopy,X-ray diffraction (XRD),scanning electron microscopy (SEM),transmission electron microscopy (TEM) and N2 adsorption-desorption measurements.The experimental results show that bimodal mesoporous silica consists of small mesopores of about 3 nm and large mesopores of about 45 nm.The small mesopores which were formed on the external surface and pore walls of the silica gel had similar characters with those of MCM-41,while large mesopores were inherited from parent silica gel material.The pore size distribution of the synthesized silica can be adjusted by changing the relative content of TEOS and silica gel or the feeding sequence of silica gel and NH4OH.

  17. Refining Bimodal Microstructure of Materials with MSTRUCT

    OpenAIRE

    Matěj, Z.; Kadlecová, A.; Janeček, M.; Matějová, L. (Lenka); Dopita, M.; Kužel, R.

    2014-01-01

    The possibilities of modelling the diffraction profiles from bimodal microstructure in computer program MSTRUCT are demonstrated on two examples. A special Double Component profile effect can be utilized for such problems. At first it was applied to an analysis of a mixture of two nanocrystalline anatase powders with different crystallite sizes and the relative ratio of both components was determined from X-ray diffraction data. In the second case study, diffraction peaks from a pure polycry...

  18. Biomimetic synthesized bimodal nanoporous silica: Bimodal mesostructure formation and application for ibuprofen delivery.

    Science.gov (United States)

    Li, Jing; Xu, Lu; Zheng, Nan; Wang, Hongyu; Lu, Fangzheng; Li, Sanming

    2016-01-01

    The present paper innovatively reports bimodal nanoporous silica synthesized using biomimetic method (B-BNS) with synthesized polymer (C16-L-serine) as template. Formation mechanism of B-BNS was deeply studied and exploration of its application as carrier of poorly water-soluble drug ibuprofen (IBU) was conducted. The bimodal nanopores and curved mesoscopic channels of B-BNS were achieved due to the dynamic self-assembly of C16-L-serine induced by silane coupling agent (3-aminopropyltriethoxysilane, APTES) and silica source (tetraethoxysilane, TEOS). Characterization results confirmed the successful synthesis of B-BNS, and particularly, nitrogen adsorption/desorption measurement demonstrated that B-BNS was meso-meso porous silica material. In application, B-BNS loaded IBU with high drug loading content due to its enlarged nanopores. After being loaded, IBU presented amorphous phase because nanoporous space and curved mesoscopic channels of B-BNS prevented the crystallization of IBU. In vitro release result revealed that B-BNS controlled IBU release with two release phases based on bimodal nanopores and improved dissolution in simulated gastric fluid due to crystalline conversion of IBU. It is convincible that biomimetic method provides novel theory and insight for synthesizing bimodal nanoporous silica, and unique functionalities of B-BNS as drug carrier can undoubtedly promote the application of bimodal nanoporous silica and development of pharmaceutical science. PMID:26478410

  19. Noise-correlation-time-mediated localization in random nonlinear dynamical systems

    CERN Document Server

    Cabrera, J L; De la Rubia, F J; Cabrera, Juan L.

    1999-01-01

    We investigate the behavior of the residence times density function for different nonlinear dynamical systems with limit cycle behavior and perturbed parametrically with a colored noise. We present evidence that underlying the stochastic resonancelike behavior with the noise correlation time, there is an effect of optimal localization of the system trajectories in the phase space. This phenomenon is observed in systems with different nonlinearities, suggesting a degree of universality.

  20. Fuzzy Forests: Extending Random Forests for Correlated, High-Dimensional Data

    OpenAIRE

    Conn, Daniel; Ngun, Tuck; Li, Gang; Ramirez, Christina

    2015-01-01

    In this paper we introduce fuzzy forests, a novel machine learning algorithm for ranking the importance of features in high-dimensional classication and regression problems. Fuzzy forests is specically designed to provide relatively unbiased rankings of variable importance in the presence of highly correlated features, especially when p >> n . We introduce our implementation of fuzzy forests in the R  package, fuzzyforest . Fuzzy forests works by t...

  1. Stochastic resonance and chaotic resonance in bimodal maps: A case study

    Indian Academy of Sciences (India)

    G Ambika; N V Sujatha; K P Harikrishnan

    2002-09-01

    We present the results of an extensive numerical study on the phenomenon of stochastic resonance in a bimodal cubic map. Both Gaussian random noise as well as deterministic chaos are used as input to drive the system between the basins. Our main result is that when two identical systems capable of stochastic resonance are coupled, the SNR of either system is enhanced at an optimum coupling strength. Our results may be relevant for the study of stochastic resonance in biological systems.

  2. Phase Diagram and Tricritical Behavior of a Spin-2 Transverse Ising Model in aRandom Field

    Institute of Scientific and Technical Information of China (English)

    LIANGYa-Qiu; WEIGuo-Zhu; SONGLi-Li; SONGGuo-Li; ZANGShu-Liang

    2004-01-01

    The phase diagrams of a spin-2 transverse Ising model with a random field on honeycomb, square, and simple-cubic lattices, respectively, are investigated within the framework of an effective-field theory with correlations.We find the behavior of the tricritical point and the reentrant phenomenon for the system with any coordination number z, when the applied random field is bimodal. The behavior of the tricritical point is also examined as a function of applied transverse field. The reentrant phenomenon comes from the competition between the transverse field and the random field.

  3. Statistical properties of a filtered Poisson process with additive random noise: Distributions, correlations and moment estimation

    CERN Document Server

    Theodorsen, Audun; Rypdal, Martin

    2016-01-01

    The filtered Poisson process is often used as a reference model for intermittent fluctuations in physical systems. Here, this process is extended by adding a noise term, either as a purely additive term to the process or as a dynamical term in a stochastic differential equation. The moments, probability density function, auto- correlation function and power spectral density are derived and used to compare the effects of the different noise terms. Monte-Carlo studies of synthetic time series are used to investigate the accuracy of parameter estimation and to identify methods for separating the noise types. It is shown that the probability density function and the three lowest moments provide accurate estimations of the parameters, but are unable to separate the noise types. The auto-correlation function and the power spectral density also provide methods for estimating the model parameters, as well as being capable of determining the noise type. The number of times the signal passes a prescribed threshold in t...

  4. Enhanced Ovarian Folliclular Development by Metformin Does Not Correlate with Pregnancy Rate: A Randomized Trial

    Directory of Open Access Journals (Sweden)

    Zahra Basirat

    2012-01-01

    Full Text Available Background: Polycystic ovary syndrome (PCOS is a common, complex endocrinedisorder for women of productive age. A high incidence of ovulation failure in womenwith PCOS is related to insulin resistance. Some studies have assessed the effects ofhyperinsulinemia and insulin resistance in relationship with insulin sensitizing agentssuch as Metformin (Met. These medicines have been suggested new scope for ovulationstimulation enhancement with Clomiphene Citrate (CC in PCOs women. The aimof this study is to compare the effectiveness of adding Met to CC in women with PCOS.Materials and Methods: This multicenter, single-blind, randomized controlled trialstudy was performed on 334 PCOS patients from 2007 to 2009. Patients were randomlydivided into two groups and ovulation induction was performed with either CC alone orCC + Met. The treatment was continued for three cycles, then the mature follicle andpregnancy rates were evaluated.Results: In the CC + Met group, 68% had at least one dominant follicle in the first cyclethat was significant (p<0.001, and 31.7% had one in the second cycle. In the CC group54.5% in the first cycle, 31.7% second cycle, and 6.9% ovulated in the third cycle. Thepregnancy rate was 28.7% in CC + Met group and 24.6% in the CC group, with no significantdifferences between the two groups.

  5. Self-consistent random phase approximation - application to systems of strongly correlated fermions

    International Nuclear Information System (INIS)

    In the present thesis we have applied the self consistent random phase approximation (SCRPA) to the Hubbard model with a small number of sites (a chain of 2, 4, 6,... sites). Earlier SCRPA had produced very good results in other models like the pairing model of Richardson. It was therefore interesting to see what kind of results the method is able to produce in the case of a more complex model like the Hubbard model. To our great satisfaction the case of two sites with two electrons (half-filling) is solved exactly by the SCRPA. This may seem a little trivial but the fact is that other respectable approximations like 'GW' or the approach with the Gutzwiller wave function yield results still far from exact. With this promising starting point, the case of 6 sites at half filling was considered next. For that case, evidently, SCRPA does not any longer give exact results. However, they are still excellent for a wide range of values of the coupling constant U, covering for instance the phase transition region towards a state with non zero magnetisation. We consider this as a good success of the theory. Non the less the case of 4 sites (a plaquette), as indeed all cases with 4n sites at half filling, turned out to have a problem because of degeneracies at the Hartree Fock level. A generalisation of the present method, including in addition to the pairs, quadruples of Fermions operators (called second RPA) is proposed to also include exactly the plaquette case in our approach. This is therefore a very interesting perspective of the present work. (author)

  6. EEG, HRV and Psychological Correlates while Playing Bejeweled II: A Randomized Controlled Study.

    Science.gov (United States)

    Russoniello, Carmen V; O'Brien, Kevin; Parks, Jennifer M

    2009-01-01

    Stress related medical disorders such as cardiovascular disease, diabetes, depression, and anxiety are serious medical issues that can cause disability and death. Interventions to prevent their development and exacerbation are needed. Casual video games (CVGs) are fun, easy to play, spontaneous and tremendously popular. People report that they play these games because they decrease their stress and improve their mood. This study tested this theory by comparing people playing Bejeweled II a popular CVG with control subjects measured under similar conditions. Electroencephalographic (EEG) changes after playing Bejeweled II were consistent with increased mood and corroborated with similar findings on psychological reports. Moreover, heart rate variability (HRV) changes consistent with autonomic nervous system relaxation or decreased physical stress were also recorded. It is concluded, therefore, that playing a CVG like Bejeweled II can increase mood and decrease stress. These finding have broad implications and include the potential development of prescriptive interventions using Bejeweled II to prevent and treat stress related medical disorders. Finally, these findings demonstrate a method using EEG, HRV and psychological correlates to understand the psychophysiological or cybernetic interconnection between participant and video game. PMID:19592761

  7. Optimization of phase contrast in bimodal amplitude modulation AFM

    OpenAIRE

    Mehrnoosh Damircheli; Amir F. Payam; Ricardo Garcia

    2015-01-01

    Bimodal force microscopy has expanded the capabilities of atomic force microscopy (AFM) by providing high spatial resolution images, compositional contrast and quantitative mapping of material properties without compromising the data acquisition speed. In the first bimodal AFM configuration, an amplitude feedback loop keeps constant the amplitude of the first mode while the observables of the second mode have not feedback restrictions (bimodal AM). Here we study the conditions to enhance the ...

  8. Bidirectional grapheme-phoneme activation in a bimodal detection task

    OpenAIRE

    Dijkstra, Ton; Frauenfelder, Ulrich Hans; Schreuder, Robert

    1993-01-01

    A divided attention paradigm was used to investigate whether graphemes and phonemes can mutually activate or inhibit each other during bimodal processing. In 3 experiments, Dutch subjects reacted to visual and auditory targets in single-channel or bimodal stimuli. In some bimodal conditions, the visual and auditory targets were nominally identical or redundant (e.g., visual A and auditory /a/); in others they were not (e.g., visual U and auditory /a/). Temporal aspects of cross-modal activati...

  9. Alert-derivative bimodal space power and propulsion systems

    International Nuclear Information System (INIS)

    Safe, reliable, low-mass bimodal space power and propulsion systems could have numerous civilian and military applications. This paper discusses potential bimodal systems that could be derived from the ALERT space fission power supply concept. These bimodal concepts have the potential for providing 5 to 10 kW of electrical power and a total impulse of 100 MN-s at an average specific impulse of 770 s. System mass is on the order of 1000 kg

  10. Reactive Sintering of Bimodal WC-Co Hardmetals

    OpenAIRE

    Marek Tarraste; Kristjan Juhani; Jüri Pirso; Mart Viljus

    2015-01-01

    Bimodal WC-Co hardmetals were produced using novel technology - reactive sintering. Milled and activated tungsten and graphite powders were mixed with commercial coarse grained WC-Co powder and then sintered. The microstructure of produced materials was free of defects and consisted of evenly distributed coarse and fine tungsten carbide grains in cobalt binder. The microstructure, hardness and fracture toughness of reactive sintered bimodal WC-Co hardmetals is exhibited. Developed bimodal har...

  11. Structural Stability of Planar Bimodal Linear Systems

    Directory of Open Access Journals (Sweden)

    Josep Ferrer

    2014-01-01

    Full Text Available Structural stability ensures that the qualitative behavior of a system is preserved under small perturbations. We study it for planar bimodal linear dynamical systems, that is, systems consisting of two linear dynamics acting on each side of a given hyperplane and assuming continuity along the separating hyperplane. We describe which one of these systems is structurally stable when (real spiral does not appear and when it does we give necessary and sufficient conditions concerning finite periodic orbits and saddle connections. In particular, we study the finite periodic orbits and the homoclinic orbits in the saddle/spiral case.

  12. Quality of life in bimodal hearing users (unilateral cochlear implants and contralateral hearing aids).

    Science.gov (United States)

    Farinetti, A; Roman, S; Mancini, J; Baumstarck-Barrau, K; Meller, R; Lavieille, J P; Triglia, J M

    2015-11-01

    The main objective was to evaluate the bimodal self-rated benefits on auditory performance under real conditions and the quality of life in two groups of cochlear-implanted adults, with or without a contralateral hearing aid. The secondary objective was to investigate correlations between the use of a hearing aid and residual hearing on the non-implanted ear. This retrospective study was realized between 2000 and 2010 in two referral centers. A population of 183 postlingually deaf adults, implanted with a cochlear experience superior to 6 months, was selected. The Speech, Spatial, and other Qualities of Hearing Scale were administered to evaluate the auditory performances, and the Nijmegen Cochlear Implant Questionnaire to evaluate the quality of life. The population was divided into two groups: a group with unilateral cochlear implants (Cochlear Implant-alone, n = 54), and a bimodal group with a cochlear implant and a contralateral hearing aid (n = 62). Both groups were similar in terms of auditory deprivation duration, duration of cochlear implant use, and pure-tone average on the implanted ear. There was a significant difference in terms of pure-tone average on low and low-to-mid frequencies on the non-implanted ear. The scores on both questionnaires showed an improvement in the basic sound perception and quality of social activities for the bimodal group. The results suggest that the bimodal stimulation (cochlear implant and contralateral hearing aid) improved auditory perception in quiet and the quality of life domain of social activities. PMID:25373837

  13. Hierarchical random additive process and logarithmic scaling of generalized high order, two-point correlations in turbulent boundary layer flow

    Science.gov (United States)

    Yang, X. I. A.; Marusic, I.; Meneveau, C.

    2016-06-01

    Townsend [Townsend, The Structure of Turbulent Shear Flow (Cambridge University Press, Cambridge, UK, 1976)] hypothesized that the logarithmic region in high-Reynolds-number wall-bounded flows consists of space-filling, self-similar attached eddies. Invoking this hypothesis, we express streamwise velocity fluctuations in the inertial layer in high-Reynolds-number wall-bounded flows as a hierarchical random additive process (HRAP): uz+=∑i=1Nzai . Here u is the streamwise velocity fluctuation, + indicates normalization in wall units, z is the wall normal distance, and ai's are independently, identically distributed random additives, each of which is associated with an attached eddy in the wall-attached hierarchy. The number of random additives is Nz˜ln(δ /z ) where δ is the boundary layer thickness and ln is natural log. Due to its simplified structure, such a process leads to predictions of the scaling behaviors for various turbulence statistics in the logarithmic layer. Besides reproducing known logarithmic scaling of moments, structure functions, and correlation function [" close="]3/2 uz(x ) uz(x +r ) >, new logarithmic laws in two-point statistics such as uz4(x ) > 1 /2, 1/3, etc. can be derived using the HRAP formalism. Supporting empirical evidence for the logarithmic scaling in such statistics is found from the Melbourne High Reynolds Number Boundary Layer Wind Tunnel measurements. We also show that, at high Reynolds numbers, the above mentioned new logarithmic laws can be derived by assuming the arrival of an attached eddy at a generic point in the flow field to be a Poisson process [Woodcock and Marusic, Phys. Fluids 27, 015104 (2015), 10.1063/1.4905301]. Taken together, the results provide new evidence supporting the essential ingredients of the attached eddy hypothesis to describe streamwise velocity fluctuations of large, momentum transporting eddies in wall-bounded turbulence, while observed deviations suggest the need for further extensions of the

  14. Correlation of finite element free vibration predictions using random vibration test data. M.S. Thesis - Cleveland State Univ.

    Science.gov (United States)

    Chambers, Jeffrey A.

    1994-01-01

    Finite element analysis is regularly used during the engineering cycle of mechanical systems to predict the response to static, thermal, and dynamic loads. The finite element model (FEM) used to represent the system is often correlated with physical test results to determine the validity of analytical results provided. Results from dynamic testing provide one means for performing this correlation. One of the most common methods of measuring accuracy is by classical modal testing, whereby vibratory mode shapes are compared to mode shapes provided by finite element analysis. The degree of correlation between the test and analytical mode shapes can be shown mathematically using the cross orthogonality check. A great deal of time and effort can be exhausted in generating the set of test acquired mode shapes needed for the cross orthogonality check. In most situations response data from vibration tests are digitally processed to generate the mode shapes from a combination of modal parameters, forcing functions, and recorded response data. An alternate method is proposed in which the same correlation of analytical and test acquired mode shapes can be achieved without conducting the modal survey. Instead a procedure is detailed in which a minimum of test information, specifically the acceleration response data from a random vibration test, is used to generate a set of equivalent local accelerations to be applied to the reduced analytical model at discrete points corresponding to the test measurement locations. The static solution of the analytical model then produces a set of deformations that once normalized can be used to represent the test acquired mode shapes in the cross orthogonality relation. The method proposed has been shown to provide accurate results for both a simple analytical model as well as a complex space flight structure.

  15. The Bimodality Index: A Criterion for Discovering and Ranking Bimodal Signatures from Cancer Gene Expression Profiling Data

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2009-01-01

    Full Text Available Motivation: Identifying genes with bimodal expression patterns from large-scale expression profiling data is an important analytical task. Model-based clustering is popular for this purpose. That technique commonly uses the Bayesian information criterion (BIC for model selection. In practice, however, BIC appears to be overly sensitive and may lead to the identification of bimodally expressed genes that are unreliable or not clinically useful. We propose using a novel criterion, the bimodality index, not only to identify but also to rank meaningful and reliable bimodal patterns. The bimodality index can be computed using either a mixture model-based algorithm or Markov chain Monte Carlo techniques.Results: We carried out simulation studies and applied the method to real data from a cancer gene expression profiling study. Our findings suggest that BIC behaves like a lax cutoff based on the bimodality index, and that the bimodality index provides an objective measure to identify and rank meaningful and reliable bimodal patterns from large-scale gene expression datasets. R code to compute the bimodality index is included in the ClassDiscovery package of the Object-Oriented Microarray and Proteomic Analysis (OOMPA suite available at the web site http://bioinformatics.mdanderson.org/Software/OOMPA.

  16. Transfer learning for bimodal biometrics recognition

    Science.gov (United States)

    Dan, Zhiping; Sun, Shuifa; Chen, Yanfei; Gan, Haitao

    2013-10-01

    Biometrics recognition aims to identify and predict new personal identities based on their existing knowledge. As the use of multiple biometric traits of the individual may enables more information to be used for recognition, it has been proved that multi-biometrics can produce higher accuracy than single biometrics. However, a common problem with traditional machine learning is that the training and test data should be in the same feature space, and have the same underlying distribution. If the distributions and features are different between training and future data, the model performance often drops. In this paper, we propose a transfer learning method for face recognition on bimodal biometrics. The training and test samples of bimodal biometric images are composed of the visible light face images and the infrared face images. Our algorithm transfers the knowledge across feature spaces, relaxing the assumption of same feature space as well as same underlying distribution by automatically learning a mapping between two different but somewhat similar face images. According to the experiments in the face images, the results show that the accuracy of face recognition has been greatly improved by the proposed method compared with the other previous methods. It demonstrates the effectiveness and robustness of our method.

  17. A note on bimodal singularities and mirror symmetry

    OpenAIRE

    Mase, Makiko; UEDA, Kazushi

    2014-01-01

    We discuss the relation between transposition mirror symmetry of Berlund and H\\"ubsch for bimodal singularities and polar duality of Batyrev for associated toric K3 hypersurfaces. We also show that homological mirror symmetry for singularities implies the geometric construction of Coxeter-Dynkin diagrams of bimodal singularities by Ebeling and Ploog.

  18. Energetic Argument for Bimodal Black Hole Accretion discs

    Institute of Scientific and Technical Information of China (English)

    林一清; 卢炬甫; 顾为民

    2002-01-01

    Based on simple energetic considerations, we show that two crucial ingredients of bimodal black hole accretiondiscs, namely the sonic point and the transition radius, can be determined from the disc constant parameters.Thus, we can further justify the model of bimodal discs containing thermal instability triggered transition.

  19. The Bimodal Bilingual Brain: Effects of Sign Language Experience

    Science.gov (United States)

    Emmorey, Karen; McCullough, Stephen

    2009-01-01

    Bimodal bilinguals are hearing individuals who know both a signed and a spoken language. Effects of bimodal bilingualism on behavior and brain organization are reviewed, and an fMRI investigation of the recognition of facial expressions by ASL-English bilinguals is reported. The fMRI results reveal separate effects of sign language and spoken…

  20. Differentiable Families of Planar Bimodal Linear Control Systems

    OpenAIRE

    Josep Ferrer; M. Dolors Magret; Marta Peña

    2014-01-01

    We consider bimodal linear control systems consisting of two subsystems acting on each side of a given hyperplane, assuming continuity along it. For a differentiable family of planar bimodal linear control systems, we obtain its stratification diagram and, if controllability holds for each value of the parameters, we construct a differentiable family of feedbacks which stabilizes both subsystems for each value of the parameters.

  1. Bimodal stimulation: benefits for music perception and sound quality.

    Science.gov (United States)

    Sucher, Catherine M; McDermott, Hugh J

    2009-01-01

    With recent expansions in cochlear implantation candidacy criteria, increasing numbers of implantees can exploit their remaining hearing by using bimodal stimulation (combining electrical stimulation via the implant with acoustic stimulation via hearing aids). This study examined the effect of bimodal stimulation on music perception and perceived sound quality. The perception of music and sound quality by nine post-lingually deafened adult implantees was examined in three conditions: implant alone, hearing aid alone and bimodal stimulation. On average, bimodal stimulation provided the best results for music perception and perceived sound quality when compared with results obtained with electrical stimulation alone. Thus, for implantees with usable acoustic hearing, bimodal stimulation may be advantageous when listening to music and other non-speech sounds. PMID:19230032

  2. Optimization of phase contrast in bimodal amplitude modulation AFM

    Directory of Open Access Journals (Sweden)

    Mehrnoosh Damircheli

    2015-04-01

    Full Text Available Bimodal force microscopy has expanded the capabilities of atomic force microscopy (AFM by providing high spatial resolution images, compositional contrast and quantitative mapping of material properties without compromising the data acquisition speed. In the first bimodal AFM configuration, an amplitude feedback loop keeps constant the amplitude of the first mode while the observables of the second mode have not feedback restrictions (bimodal AM. Here we study the conditions to enhance the compositional contrast in bimodal AM while imaging heterogeneous materials. The contrast has a maximum by decreasing the amplitude of the second mode. We demonstrate that the roles of the excited modes are asymmetric. The operational range of bimodal AM is maximized when the second mode is free to follow changes in the force. We also study the contrast in trimodal AFM by analyzing the kinetic energy ratios. The phase contrast improves by decreasing the energy of second mode relative to those of the first and third modes.

  3. Bimodal and multimodal plant biomass particle mixtures

    Science.gov (United States)

    Dooley, James H.

    2013-07-09

    An industrial feedstock of plant biomass particles having fibers aligned in a grain, wherein the particles are individually characterized by a length dimension (L) aligned substantially parallel to the grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) normal to W and L, wherein the L.times.H dimensions define a pair of substantially parallel side surfaces characterized by substantially intact longitudinally arrayed fibers, the W.times.H dimensions define a pair of substantially parallel end surfaces characterized by crosscut fibers and end checking between fibers, and the L.times.W dimensions define a pair of substantially parallel top and bottom surfaces, and wherein the particles in the feedstock are collectively characterized by having a bimodal or multimodal size distribution.

  4. Bimodal condensation silicone elastomers as dielectric elastomers

    DEFF Research Database (Denmark)

    Yu, Liyun; Madsen, Frederikke Bahrt; Skov, Anne Ladegaard

    , the top and bottom surfaces of the elastomer (7:3) prepared at 23oC and 50% humidity were tested by water contact angle and optical microscope. The results show the bimodal condensation elastomer possesses structural heterogeneity, which may lead to favourable properties for DE applications....... elastomers were prepared by mixing different mass ratios (9:1, 8:2, 7:3, 6:4, 5:5, 4:6) between long polydimethylsiloxane (PDMS) chains and short PDMS chains. The resulting elastomers were investigated with respect to their rheology, dielectric properties, tensile strength, electrical breakdown, as well as.......Moreover, a series of elastomers with the same mass ratio (7:3) between long and short PDMS chains were made at different humidity (90%, 70%, 50%, 30%, 10%) at 23oC. The dielectric and mechincal properties of the resulting elastomers were shown to depend strongly on the atmospheric humidity level.In addition...

  5. Sex identification in female crayfish is bimodal

    Science.gov (United States)

    Aquiloni, Laura; Massolo, Alessandro; Gherardi, Francesca

    2009-01-01

    Sex identification has been studied in several species of crustacean decapods but only seldom was the role of multimodality investigated in a systematic fashion. Here, we analyse the effect of single/combined chemical and visual stimuli on the ability of the crayfish Procambarus clarkii to identify the sex of a conspecific during mating interactions. Our results show that crayfish respond to the offered stimuli depending on their sex. While males rely on olfaction alone for sex identification, females require the combination of olfaction and vision to do so. In the latter, chemical and visual stimuli act as non-redundant signal components that possibly enhance the female ability to discriminate potential mates in the crowded social context experienced during mating period. This is one of the few clear examples in invertebrates of non-redundancy in a bimodal communication system.

  6. Emergence of bimodality in controlling complex networks

    CERN Document Server

    Jia, Tao; Csóka, Endre; Pósfai, Márton; Slotine, Jean-Jacques; Barabási, Albert-László

    2015-01-01

    Our ability to control complex systems is a fundamental challenge of contemporary science. Recently introduced tools to identify the driver nodes, nodes through which we can achieve full control, predict the existence of multiple control configurations, prompting us to classify each node in a network based on their role in control. Accordingly a node is critical, intermittent or redundant if it acts as a driver node in all, some or none of the control configurations. Here we develop an analytical framework to identify the category of each node, leading to the discovery of two distinct control modes in complex systems: centralized vs distributed control. We predict the control mode for an arbitrary network and show that one can alter it through small structural perturbations. The uncovered bimodality has implications from network security to organizational research and offers new insights into the dynamics and control of complex systems.

  7. Thermodynamical Properties of Spin-3/2 Ising Model in a Longitudinal Random Field with Crystal Field

    Institute of Scientific and Technical Information of China (English)

    LIANGYa-Qiu; WEIGuo-Zhu; ZHANGHong; SONGGuo-Li

    2004-01-01

    A theoretical study of a spin-3/2 Ising model in a longitudinal random field with crystal field is studied by using of the effective-field theory with correlations. The phase diagrams and the behavior of the tricritical point are investigated numerically for the honeycomb lattice when the random field is bimodal. In particular, the specific heat and the internal energy are examined in detail for the system with a crystal-field constant in the critical region where the ground-state configuration may change from the spin-3/2 state to the spin-1/2 state. We find many interesting phenomena in the system.

  8. The non-linear dynamics of vortices subjected to correlated and random pinning disorders in a quasi-2D superconductor

    Indian Academy of Sciences (India)

    Leena K Sahoo; R C Budhani; D Kanjilal; G K Mehta

    2002-05-01

    Understanding the dynamics of vortex matter subjected to random and correlated pinning disorders in layered superconductors remains a topic of considerable interest. The dynamical behavior of vortices in these systems shows a rich variety of effects due to many competing interactions. Here, we study the ac response of as-grown as well as heavy-ion-irradiated Tl2Ba2CaCu2O8 (Tl-2212) thin films by using a micro Hall-probe susceptometer. We find that the dynamics of vortices in the high-temperature, low-field regime of the - phase diagram investigated here depends on the nature of pinning defects. While the decay of screening currents () indicates a glassy behavior in both types of samples, the nature of the glassy phase is different in the two cases. Samples with columnar defects show distinct signature of a Bose glass in the measurement of () and the angular dependence of the irreversibility field (irr).

  9. Random Projection for Fast and Efficient Multivariate Correlation Analysis of High-Dimensional Data: A New Approach

    Science.gov (United States)

    Grellmann, Claudia; Neumann, Jane; Bitzer, Sebastian; Kovacs, Peter; Tönjes, Anke; Westlye, Lars T.; Andreassen, Ole A.; Stumvoll, Michael; Villringer, Arno; Horstmann, Annette

    2016-01-01

    In recent years, the advent of great technological advances has produced a wealth of very high-dimensional data, and combining high-dimensional information from multiple sources is becoming increasingly important in an extending range of scientific disciplines. Partial Least Squares Correlation (PLSC) is a frequently used method for multivariate multimodal data integration. It is, however, computationally expensive in applications involving large numbers of variables, as required, for example, in genetic neuroimaging. To handle high-dimensional problems, dimension reduction might be implemented as pre-processing step. We propose a new approach that incorporates Random Projection (RP) for dimensionality reduction into PLSC to efficiently solve high-dimensional multimodal problems like genotype-phenotype associations. We name our new method PLSC-RP. Using simulated and experimental data sets containing whole genome SNP measures as genotypes and whole brain neuroimaging measures as phenotypes, we demonstrate that PLSC-RP is drastically faster than traditional PLSC while providing statistically equivalent results. We also provide evidence that dimensionality reduction using RP is data type independent. Therefore, PLSC-RP opens up a wide range of possible applications. It can be used for any integrative analysis that combines information from multiple sources.

  10. Bimodal score distributions and the Myers-Briggs Type Indicator: fact or artifact?

    Science.gov (United States)

    Bess, Tammy L; Harvey, Robert J

    2002-02-01

    We examined Myers-Briggs Type Indicator (MBTI) score distributions computed using item response theory (IRT) to assess the generalizability of earlier bimodality reports that have been cited in support of the "type" versus "trait" view of personality. Using the BILOG IRT program to score a sample of approximately 12,000 individuals who participated in leadership development programs, theta score distributions for the 4 dimensions of the MBTI computed using 10 (the BILOG default) versus 50 quadrature points were compared. Results indicated that past reports of bimodality were artifacts caused by BILOG's default use of a small number of quadrature points; when larger numbers of points were used, score distributions became strongly center-weighted. Although our findings are not supportive of the "type"-based hypothesis, the extremely high correlations between theta scores (rs > .996) suggest that no practical differences would be expected as a function of the number-of-quadrature-points decision. PMID:11936208

  11. Roles of factorial noise in inducing bimodal gene expression.

    Science.gov (United States)

    Liu, Peijiang; Yuan, Zhanjiang; Huang, Lifang; Zhou, Tianshou

    2015-06-01

    Some gene regulatory systems can exhibit bimodal distributions of mRNA or protein although the deterministic counterparts are monostable. This noise-induced bimodality is an interesting phenomenon and has important biological implications, but it is unclear how different sources of expression noise (each source creates so-called factorial noise that is defined as a component of the total noise) contribute separately to this stochastic bimodality. Here we consider a minimal model of gene regulation, which is monostable in the deterministic case. Although simple, this system contains factorial noise of two main kinds: promoter noise due to switching between gene states and transcriptional (or translational) noise due to synthesis and degradation of mRNA (or protein). To better trace the roles of factorial noise in inducing bimodality, we also analyze two limit models, continuous and adiabatic approximations, apart from the exact model. We show that in the case of slow gene switching, the continuous model where only promoter noise is considered can exhibit bimodality; in the case of fast switching, the adiabatic model where only transcriptional or translational noise is considered can also exhibit bimodality but the exact model cannot; and in other cases, both promoter noise and transcriptional or translational noise can cooperatively induce bimodality. Since slow gene switching and large protein copy numbers are characteristics of eukaryotic cells, whereas fast gene switching and small protein copy numbers are characteristics of prokaryotic cells, we infer that eukaryotic stochastic bimodality is induced mainly by promoter noise, whereas prokaryotic stochastic bimodality is induced primarily by transcriptional or translational noise. PMID:26172735

  12. Galaxy bimodality versus stellar mass and environment

    CERN Document Server

    Baldry, I; Bower, R; Glazebrook, K; Nichol, R; Bamford, S; Budavari, T

    2006-01-01

    We analyse a z<0.1 galaxy sample from the Sloan Digital Sky Survey focusing on the variation of the galaxy colour bimodality with stellar mass and projected neighbour density Sigma, and on measurements of the galaxy stellar mass functions. The characteristic mass increases with environmental density from about 10^10.6 Msun to 10^10.9 Msun (Kroupa IMF, H_0=70) for Sigma in the range 0.1--10 per Mpc^2. The galaxy population naturally divides into a red and blue sequence with the locus of the sequences in colour-mass and colour-concentration index not varying strongly with environment. The fraction of galaxies on the red sequence is determined in bins of 0.2 in log Sigma and log mass (12 x 13 bins). The red fraction f_r generally increases continuously in both Sigma and mass such that there is a unified relation: f_r = F(Sigma,mass). Two simple functions are proposed which provide good fits to the data. These data are compared with analogous quantities in semi-analytical models based on the Millennium N-body ...

  13. Earth storable bimodal engine, phase 1

    Science.gov (United States)

    1973-01-01

    An in-depth study of an Earth Storable Bimodal (ESB) Engine using earth storable propellants N2O/N2H4 and operating in either a monopropellant or bipropellant mode was conducted. Detailed studies were completed for both a hot-gas, regeneratively cooled thrust chamber and a ducted hot-gas, film cooled thrust chamber. Hydrazine decomposition products were used for cooling in either configuration. The various arrangements and configurations of hydrazine reactors, secondary injectors, chambers and gimbal methods were considered. The two basic materials selected for the major components were columbium alloys and L-605. The secondary injector types considered were previously demonstrated by JPL and consisted of a liquid-on-gas triplet, a liquid-on-gas doublet, and a liquid-on-gas coaxial injector. Various design tradeoffs were made with different reactor types located at: the secondary injector station, the thrust chamber throat, and the nozzle/extension interface. Associated thermal, structural, and mass analyses were completed.

  14. Bi-Modal Methods: An Overview

    Directory of Open Access Journals (Sweden)

    Olatunji K. A

    2015-07-01

    Full Text Available Various security challenges such as Boko Haram, theft, kidnapping, ISIL, abduction, and so on have been on a high rise as one of the major menace facing our society today. In order to overcome these challenges there is need for identification of the culprits to bring them to book. Uni-modal biometric is not enough to combat these security challenges because of its shortcomings which include- spoof attach, noise in the sensed data, inter class variation and so on. Combining two or more biometric features (bi-modal has been proved to provide better performance than uni-modal biometric approach for authentication and verification. This paper presents some literature on biometrics systems that can be employed in achieving a better accuracy in authentication and verification of biometric features. Different kind of fusion strategies to combine these characteristics, different available classifiers and fusion methodologies to achieve greater and accurate recognition performance were also discussed. It is hopeful that researchers in the area of biometrics will find this work very useful.

  15. Audiovisual bimodal mutual compensation of Chinese

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The perception of human languages is inherently a multi-modalprocess, in which audio information can be compensated by visual information to improve the recognition performance. Such a phenomenon in English, German, Spanish and so on has been researched, but in Chinese it has not been reported yet. In our experiment, 14 syllables (/ba, bi, bian, biao, bin, de, di, dian, duo, dong, gai, gan, gen, gu/), extracted from Chinese audiovisual bimodal speech database CAVSR-1.0, were pronounced by 10 subjects. The audio-only stimuli, audiovisual stimuli, and visual-only stimuli were recognized by 20 observers. The audio-only stimuli and audiovisual stimuli both were presented under 5 conditions: no noise, SNR 0 dB, -8 dB, -12 dB, and -16 dB. The experimental result is studied and the following conclusions for Chinese speech are reached. Human beings can recognize visual-only stimuli rather well. The place of articulation determines the visual distinction. In noisy environment, audio information can remarkably be compensated by visual information and as a result the recognition performance is greatly improved.

  16. Audiovisual bimodal mutual compensation of Chinese

    Institute of Scientific and Technical Information of China (English)

    ZHOU; Zhi

    2001-01-01

    [1]Richard, P., Schumeyer, Kenneth E. B., The effect of visual information on word initial consonant perception of dysarthric speech, in Proc. ICSLP'96 October 3-6 1996, Philadephia, Pennsylvania, USA.[2]Goff, B. L., Marigny, T. G., Benoit, C., Read my lips...and my jaw! How intelligible are the components of a speaker's face? Eurospeech'95, 4th European Conference on Speech Communication and Technology, Madrid, September 1995.[3]McGurk, H., MacDonald, J. Hearing lips and seeing voices, Nature, 1976, 264: 746.[4]Duran A. F., Mcgurk effect in Spanish and German listeners: Influences of visual cues in the perception of Spanish and German confliction audio-visual stimuli, Eurospeech'95. 4th European Conference on Speech Communication and Technology, Madrid, September 1995.[5]Luettin, J., Visual speech and speaker recognition, Ph.D thesis, University of Sheffield, 1997.[6]Xu Yanjun, Du Limin, Chinese audiovisual bimodal speech database CAVSR1.0, Chinese Journal of Acoustics, to appear.[7]Zhang Jialu, Speech corpora and language input/output methods' evaluation, Chinese Applied Acoustics, 1994, 13(3): 5.

  17. Intelligent agents: adaptation of autonomous bimodal microsystems

    Science.gov (United States)

    Smith, Patrice; Terry, Theodore B.

    2014-03-01

    Autonomous bimodal microsystems exhibiting survivability behaviors and characteristics are able to adapt dynamically in any given environment. Equipped with a background blending exoskeleton it will have the capability to stealthily detect and observe a self-chosen viewing area while exercising some measurable form of selfpreservation by either flying or crawling away from a potential adversary. The robotic agent in this capacity activates a walk-fly algorithm, which uses a built in multi-sensor processing and navigation subsystem or algorithm for visual guidance and best walk-fly path trajectory to evade capture or annihilation. The research detailed in this paper describes the theoretical walk-fly algorithm, which broadens the scope of spatial and temporal learning, locomotion, and navigational performances based on optical flow signals necessary for flight dynamics and walking stabilities. By observing a fly's travel and avoidance behaviors; and, understanding the reverse bioengineering research efforts of others, we were able to conceptualize an algorithm, which works in conjunction with decisionmaking functions, sensory processing, and sensorimotor integration. Our findings suggest that this highly complex decentralized algorithm promotes inflight or terrain travel mobile stability which is highly suitable for nonaggressive micro platforms supporting search and rescue (SAR), and chemical and explosive detection (CED) purposes; a necessity in turbulent, non-violent structured or unstructured environments.

  18. INTEGRATING NEPHELOMETER RESPONSE CORRECTIONS FOR BIMODAL SIZE DISTRIBUTIONS

    Science.gov (United States)

    Correction factors are calculated for obtaining true scattering extinction coefficients from integrating nephelometer measurements. The corrections are based on the bimodal representation of ambient aerosol size distributions, and take account of the effects of angular truncation...

  19. Reactive Sintering of Bimodal WC-Co Hardmetals

    Directory of Open Access Journals (Sweden)

    Marek Tarraste

    2015-09-01

    Full Text Available Bimodal WC-Co hardmetals were produced using novel technology - reactive sintering. Milled and activated tungsten and graphite powders were mixed with commercial coarse grained WC-Co powder and then sintered. The microstructure of produced materials was free of defects and consisted of evenly distributed coarse and fine tungsten carbide grains in cobalt binder. The microstructure, hardness and fracture toughness of reactive sintered bimodal WC-Co hardmetals is exhibited. Developed bimodal hardmetal has perspective for demanding wear applications for its increased combined hardness and toughness. Compared to coarse material there is only slight decrease in fracture toughness (K1c is 14.7 for coarse grained and 14.4 for bimodal, hardness is increased from 1290 to 1350 HV units.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7511

  20. Functionalized bimodal mesoporous silicas as carriers for controlled aspirin delivery

    Science.gov (United States)

    Gao, Lin; Sun, Jihong; Li, Yuzhen

    2011-08-01

    The bimodal mesoporous silica modified with 3-aminopropyltriethoxysilane was performed as the aspirin carrier. The samples' structure, drug loading and release profiles were characterized with X-ray diffraction, scanning electron microscopy, N 2 adsorption and desorption, Fourier transform infrared spectroscopy, TG analysis, elemental analysis and UV-spectrophotometer. For further exploring the effects of the bimodal mesopores on the drug delivery behavior, the unimodal mesoporous material MCM-41 was also modified as the aspirin carrier. Meantime, Korsmeyer-Peppas equation ft= ktn was employed to analyze the dissolution data in details. It is indicated that the bimodal mesopores are beneficial for unrestricted drug molecules diffusing and therefore lead to a higher loading and faster releasing than that of MCM-41. The results show that the aspirin delivery properties are influenced considerably by the mesoporous matrix, whereas the large pore of bimodal mesoporous silica is the key point for the improved controlled-release properties.

  1. Bimodal magmatism produced by progressively inhibited crustal assimilation.

    Science.gov (United States)

    Meade, F C; Troll, V R; Ellam, R M; Freda, C; Font, L; Donaldson, C H; Klonowska, I

    2014-01-01

    The origin of bimodal (mafic-felsic) rock suites is a fundamental question in volcanology. Here we use major and trace elements, high-resolution Sr, Nd and Pb isotope analyses, experimental petrology and thermodynamic modelling to investigate bimodal magmatism at the iconic Carlingford Igneous Centre, Ireland. We show that early microgranites are the result of extensive assimilation of trace element-enriched partial melts of local metasiltstones into mafic parent magmas. Melting experiments reveal the crust is very fusible, but thermodynamic modelling indicates repeated heating events rapidly lower its melt-production capacity. Granite generation ceased once enriched partial melts could no longer form and subsequent magmatism incorporated less fertile restite compositions only, producing mafic intrusions and a pronounced compositional gap. Considering the frequency of bimodal magma suites in the North Atlantic Igneous Province, and the ubiquity of suitable crustal compositions, we propose 'progressively inhibited crustal assimilation' (PICA) as a major cause of bimodality in continental volcanism. PMID:24947142

  2. On the controllability of bimodal piecewise linear systems

    OpenAIRE

    Çamlıbel, Mehmet Kanat; Heemels, W.P.M.H.; Schumacher, J.M.

    2004-01-01

    This paper studies controllability of bimodal systems that consist of two linear dynamics on each side of a given hyperplane. We show that the controllability properties of these systems can be inferred from those of linear systems for which the inputs are constrained in a certain way. Inspired by the earlier work on constrained controllability of linear systems, we derive necessary and sufficient conditions for a bimodal piecewise linear system to be controllable.

  3. Right unimodal and bimodal singularities in positive characteristic

    OpenAIRE

    Nguyen, Hong Duc

    2015-01-01

    The problem of classification of real and complex singularities was initiated by Arnol'd in the sixties who classified simple, unimodal and bimodal w.r.t. right equivalence. The classification of right simple singularities in positive characteristic was achieved by Greuel and the author in 2014. In the present paper we classify right unimodal and bimodal singularities in positive characteristic by giving explicit normal forms. Moreover we completely determine all possible adjacencies of simpl...

  4. Learning bimodal structure in audio-visual data

    OpenAIRE

    Monaci, Gianluca; Vandergheynst, Pierre; Sommer, Friederich T.

    2009-01-01

    A novel model is presented to learn bimodally informative structures from audio-visual signals. The signal is represented as a sparse sum of audio- visual kernels. Each kernel is a bimodal function consisting of synchronous snippets of an audio waveform and a spatio-temporal visual basis function. To represent an audio-visual signal, the kernels can be positioned independently and arbitrarily in space and time. The proposed algorithm uses unsupervised learning to form dicti...

  5. Microstructure, plastic deformation and strengthening mechanisms of an Al–Mg–Si alloy with a bimodal grain structure

    Energy Technology Data Exchange (ETDEWEB)

    Shakoori Oskooie, M. [Department of Materials Engineering, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Asgharzadeh, H., E-mail: asgharzadeh@tabrizu.ac.ir [Department of Materials Engineering, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Kim, H.S. [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of)

    2015-05-25

    Highlights: • Al6063 with bimodal grain structures was fabricated by a powder metallurgy route. • The bimodal alloys showed a reasonable ductility together with a high strength. • Grain boundary strengthening was reduced at higher fraction of coarse grains. • The enhanced tensile ductility was attributed to crack blunting and delamination. - Abstract: Al6063 alloys with bimodal grain size distributions comprised of ultrafine-grained (UFG) and coarse-grained (CG) regions were produced via mechanical milling followed by hot extrusion. High-energy planetary ball milling for 22.5 h with a rotational speed of 350 rpm was employed for the synthesis of nanocrystalline Al6063 powders. The as-milled Al6063 powders were mixed with 15, 30, and 45 vol.% of the unmilled powders and then the powder mixtures were consolidated via extrusion at 450 °C with an extrusion ratio of 9:1. The microstructure of the bimodal extrudates was investigated using optical microscope, transmission electron microscope (TEM) and field emission scanning electron microscope equipped with an electron backscattered diffraction (EBSD) detector. The deformation behavior was investigated by means of uniaxial tensile tests. The bimodal Al6063 exhibited balanced mechanical properties, including high yield stress and ultimate tensile strength resulting from the UFG regions together with reasonable ductility attained from the CG areas. The fracture surfaces demonstrated a ductile fracture mode, in which the dimple size was correlated with the grain structure. The strengthening mechanisms are discussed based on the dislocation models and the functions of the CGs in the deformation behavior and ductility enhancement of bimodal Al6063 are explored.

  6. Type Ia Supernovae with Bi-Modal Explosions Are Common -- Possible Smoking Gun for Direct Collisions of White-Dwarfs

    CERN Document Server

    Dong, Subo; Kushnir, Doron; Prieto, Jose L

    2014-01-01

    We discover clear doubly-peaked line profiles in 3 out of ~20 type Ia supernovae (SNe Ia) with high-quality nebular-phase spectra. The profiles are consistently present in three well-separated Co/Fe emission features. The two peaks are respectively blue-shifted and red-shifted relative to the host galaxies and are separated by ~5000 km/s. The doubly-peaked profiles directly reflect a bi-modal velocity distribution of the radioactive Ni56 in the ejecta that powers the emission of these SNe. Due to their random orientations, only a fraction of SNe with intrinsically bi-modal velocity distributions will appear as doubly-peaked spectra. Therefore SNe with intrinsic bi-modality are likely common, especially among the SNe in the low-luminosity (~40% of all SNe Ia) part on the Philips relation \\Delta m15(B) >~ 1.3. Bi-modality is naturally expected from direct collisions of white dwarfs (WDs) due to the detonation of both WDs and is demonstrated in a 3D 0.64 M_Sun-0.64 M_Sun WD collision simulation.

  7. The Bimodality Index: A Criterion for Discovering and Ranking Bimodal Signatures from Cancer Gene Expression Profiling Data

    OpenAIRE

    Jing Wang; Sijin Wen; Fraser Symmans, W; Lajos Pusztai; Coombes, Kevin R.

    2009-01-01

    Motivation: Identifying genes with bimodal expression patterns from large-scale expression profiling data is an important analytical task. Model-based clustering is popular for this purpose. That technique commonly uses the Bayesian information criterion (BIC) for model selection. In practice, however, BIC appears to be overly sensitive and may lead to the identification of bimodally expressed genes that are unreliable or not clinically useful. We propose using a novel criterion, the bimodali...

  8. Bimodality in heavy ions collisions: systematic and comparisons

    International Nuclear Information System (INIS)

    During the last few years, bi-modality in heavy ions collisions has been observed for different systems, on large energy scale (from 35 MeV/u up to 1 GeV/u). In this thesis, the bimodal behaviour of the largest fragment distribution (Zmax) is studied for different INDRA data sets. For peripheral collisions (Au+Au from 60 to 150 MeV/u, Xe+Sn 80-100 MeV/u), the influence of sorting and selections on bi-modality is tested. Then, two different approaches based on models are considered. In the first one (ELIE), bi-modality would reflect mainly the collision geometry and the Fermi motion of the nucleon. In the second one (SMM), bi-modality would reflect a phase transition of nuclear matter. The data are in favour of the second model. Zmax can then be considered as an order parameter of the transition. A re-weighting procedure producing a flat excitation energy distribution is used to achieve comparisons between various bombarding energies and theoretical predictions based on a canonical approach. A latent heat of the transition is extracted. For central collisions (Ni+Ni from 32 to 74 MeV/u and Xe+Sn from 25 to 50 MeV/u) single source events are isolated by a Discriminant Factor Analysis. Bi-modality is then looked for, in cumulating the different incident energies and in applying the re-weighting procedure of the corresponding excitation energy as done for peripheral collisions. The bi-modality behaviour is less manifest for central collisions than for peripheral ones. The possible reasons of this difference are discussed. (author)

  9. Localization ability with bimodal hearing aids and bilateral cochlear implants

    Science.gov (United States)

    Seeber, Bernhard U.; Baumann, Uwe; Fastl, Hugo

    2004-09-01

    After successful cochlear implantation in one ear, some patients continue to use a hearing aid at the contralateral ear. They report an improved reception of speech, especially in noise, as well as a better perception of music when the hearing aid and cochlear implant are used in this bimodal combination. Some individuals in this bimodal patient group also report the impression of an improved localization ability. Similar experiences are reported by the group of bilateral cochlear implantees. In this study, a survey of 11 bimodally and 4 bilaterally equipped cochlear implant users was carried out to assess localization ability. Individuals in the bimodal implant group were all provided with the same type of hearing aid in the opposite ear, and subjects in the bilateral implant group used cochlear implants of the same manufacturer on each ear. Subjects adjusted the spot of a computer-controlled laser-pointer to the perceived direction of sound incidence in the frontal horizontal plane by rotating a trackball. Two subjects of the bimodal group who had substantial residual hearing showed localization ability in the bimodal configuration, whereas using each single device only the subject with better residual hearing was able to discriminate the side of sound origin. Five other subjects with more pronounced hearing loss displayed an ability for side discrimination through the use of bimodal aids, while four of them were already able to discriminate the side with a single device. Of the bilateral cochlear implant group one subject showed localization accuracy close to that of normal hearing subjects. This subject was also able to discriminate the side of sound origin using the first implanted device alone. The other three bilaterally equipped subjects showed limited localization ability using both devices. Among them one subject demonstrated a side-discrimination ability using only the first implanted device.

  10. Angle dependence of the frequency correlation in random photonic media: Diffusive regime and its breakdown near localization

    NARCIS (Netherlands)

    Muskens, O.L.; Beek, van der T.; Lagendijk, A.

    2011-01-01

    The frequency correlations of light in complex photonic media are of interest as a tool for characterizing the dynamical aspects of light diffusion. We demonstrate here that the frequency correlation shows a pronounced angle dependence both in transmission and in reflection geometries. Using a broad

  11. Estimates of Intraclass Correlation Coefficients from Longitudinal Group-Randomized Trials of Adolescent HIV/STI/Pregnancy Prevention Programs

    Science.gov (United States)

    Glassman, Jill R.; Potter, Susan C.; Baumler, Elizabeth R.; Coyle, Karin K.

    2015-01-01

    Introduction: Group-randomized trials (GRTs) are one of the most rigorous methods for evaluating the effectiveness of group-based health risk prevention programs. Efficiently designing GRTs with a sample size that is sufficient for meeting the trial's power and precision goals while not wasting resources exceeding them requires estimates of the…

  12. SAS Code for Calculating Intraclass Correlation Coefficients and Effect Size Benchmarks for Site-Randomized Education Experiments

    Science.gov (United States)

    Brandon, Paul R.; Harrison, George M.; Lawton, Brian E.

    2013-01-01

    When evaluators plan site-randomized experiments, they must conduct the appropriate statistical power analyses. These analyses are most likely to be valid when they are based on data from the jurisdictions in which the studies are to be conducted. In this method note, we provide software code, in the form of a SAS macro, for producing statistical…

  13. Role of Bimodal RDX in LOVA Gun Propellant Combustion

    Directory of Open Access Journals (Sweden)

    M. M. Joshi

    1998-07-01

    Full Text Available Present investigation reports the results of systematic studies on the use of bimodal RDX in low-vulnerability ammunition (LOVA gun propellants. Several formulations based on bimodal RDX as oxidiser, cellulose acetate as binder, and diocty1 phthalate or triacetin as plasticizer were processed with different proportions of 5 micrometer and 20 micrometer particle size of RDX samples in the range 100:0 to 60:40 ratios. The effect of varying the proportion of fine RDX of the two particle sizes on propellant burning behaviour was found to be quite significant. The study concluded that by using bimodal RDX, it is possible to modify burning behaviour without sacrificing low-vulnerability aspects of LOVA propellants.

  14. A hypothesis for the color bimodality of Jupiter Trojans

    CERN Document Server

    Wong, Ian

    2016-01-01

    One of the most enigmatic and hitherto unexplained properties of Jupiter Trojans is their bimodal color distribution. This bimodality is indicative of two sub-populations within the Trojans, which have distinct size distributions. In this paper, we present a simple, plausible hypothesis for the origin and evolution of the two Trojan color sub-populations. In the framework of dynamical instability models of early Solar System evolution, which suggest a common primordial progenitor population for both Trojans and Kuiper belt objects, we use observational constraints to assert that the color bimodalities evident in both minor body populations developed within the primordial population prior to the onset of instability. We show that, beginning with an initial composition of rock and ices, location-dependent volatile loss through sublimation in this primordial population could have led to sharp changes in the surface composition with heliocentric distance. We propose that the depletion or retention of H$_{2}$S ice...

  15. Observation of bimodality in nanocrystalline cobalt - ferri - chromites

    Science.gov (United States)

    Modi, K. B.; Saija, K. G.; Zankat, K. B.; Kathad, C. R.; Shah, S. J.; Lakhani, V. K.; Vasoya, N. H.; Pathak, T. K.

    2015-06-01

    In this communication we present detail analysis of particle size distribution curves, differential size distribution and cumulative undersize distribution, recorded for nano particles of spinel ferrite system, CoCrxFe2-xO4 (x = 0.0, 1.1 and 2.0), synthesized by chemical co-precipitation technique. It is found that the distribution is bimodal as well as not mono disperse. Observed bimodality has been explained in the light of Ostwald ripening. Various parameters have been determined and the role of Cr3+ - substitution in governing signature of distribution patterns has been discussed.

  16. Scheme for Generation of Entanglement among Bimodal Cavities

    Institute of Scientific and Technical Information of China (English)

    SONG Xin-Guo; FENG Xun-Li

    2004-01-01

    @@ We present a scheme for generation of an entangled state in many spatially separated bimodal cavity modes via cavity quantum electrodynamics. A V-type three-level atom, initially prepared in a coherent superposition of its excited states, successively passes through both the bimodal cavities. If the atom is measured in its ground state after leaving the last cavity, an entangled state of many cavity modes can be generated. The conditions to generate the maximally entangled state with unity probability are worked out.

  17. Combined role of molecular diffusion, mean streaming and helicity in the eddy diffusivity of short-correlated random flows

    CERN Document Server

    Afonso, Marco Martins; Gama, Sílvio

    2016-01-01

    We analytically investigate the effective-diffusivity tensor of a tracer particle in a fluid flow endowed with a short correlation time. By means of functional calculus and a multiscale expansion, we write down the main contributions to the eddy diffusivity due to each single physical effect and to their interplays. Namely, besides molecular diffusivity and a constant uniform mean streaming, we take into account the possibility for the (incompressible, Gaussian, stationary, homogeneous, isotropic) turbulent fluctuations to break parity invariance. With respect to the classical turbulence-driven diffusivity amplification for delta-correlated flows, we find that the presence of a short temporal correlation induces a diminution even when coupled with such effects, with two principal exceptions. Notably, the diffusivity is --- perturbatively --- enlarged not only by the helical contribution itself, but also by the interference between molecular diffusion and mean flow.

  18. Combinations of coupled cluster, density functionals, and the random phase approximation for describing static and dynamic correlation, and van der Waals interactions

    CERN Document Server

    Garza, Alejandro J; Alencar, Ana G Sousa; Sun, Jianwei; Perdew, John P; Scuseria, Gustavo E

    2015-01-01

    Contrary to standard coupled cluster doubles (CCD) and Brueckner doubles (BD), singlet-paired analogues of CCD and BD (denoted here as CCD0 and BD0) do not break down when static correlation is present, but neglect substantial amounts of dynamic correlation. In fact, CCD0 and BD0 do not account for any contributions from multielectron excitations involving only same-spin electrons at all. We exploit this feature to add---without introducing double counting, self-interaction, or increase in cost---the missing correlation to these methods via meta-GGA density functionals (TPSS and SCAN). Furthermore, we improve upon these CCD0+DFT blends by invoking range separation: the short- and long-range correlations absent in CCD0/BD0 are evaluated with DFT and the direct random phase approximation (dRPA), respectively. This corrects the description of long-range van der Waals forces. Comprehensive benchmarking shows that the combinations presented here are very accurate for weakly correlated systems, while also providing...

  19. PERL-2 and LAVR-2 programs for Monte Carlo calculation of reactivity disturbances with trajectory correlation using random numbers

    International Nuclear Information System (INIS)

    Realization of BESM-6 computer of a technique is described for calculating a wide class of reactivity disturbances by plotting trajectories in undisturbed and disturbed systems using one sequence of random numbers. The technique was realized on the base of earlier created programs of calculation of widespreed (PERL) and local (LAVR) reactivity disturbances. The efficiency of the technique and programs is demonstrated by calculation of change of effective neutron-multiplication factor when absorber is substituted for fuel element in a BFS-40 critical assembly and by calculation of control drum characteristics

  20. ANALYSIS OF A TWO UNIT STANDBY SYSTEM WITH CORRELATED FAILURE AND REPAIR AND RANDOM APPEARANCE AND DISAPPEARANCE OF REPAIRMAN

    Directory of Open Access Journals (Sweden)

    Rakesh Gupta

    2010-01-01

    Full Text Available The paper deals with the stochastic analysis of a two non-identical unit standbysystem model. The one unit is considered as priority (p unit and the other as ordinary (o unit.The p-unit gets priority in operation. A single repair facility appears in and disappears from thesystem randomly with constant rates. The repair discipline of units is FCFS. The joint distributionof failure and repair times for each unit is taken to be bivariate exponential. Using regenerativepoint technique various measures of system effectiveness useful to industrial managers areobtained.

  1. Correlation analysis with neutron count distributions in randomly or signal triggered time intervals for assay of special fissile materials

    International Nuclear Information System (INIS)

    A mathematical model is derived for the probability distribution of neutron signal multiplets inside randomly and signal triggered time intervals for a generalized time response function of the neutron detector assembly. The theory is applied to assemblies with an exponential time decay of its neutron population. The probability distributions, their factorial moments, and moments are expressed as a function of the spontaneous fission rate, (α-n) reaction rate, neutron detection probability, probability that a neutron generates a fast fission, and nuclear data. Measurements with plutonium sample are analyzed to check the derived algorithms for the factorial moments of the two probability distributions

  2. Response functions, trading strategies, and random matrices: Analysis of large fluctuations and correlations in stock price diffusion

    OpenAIRE

    Weber, Philipp

    2006-01-01

    In this thesis, we analyze and explain various properties of stock price changes. The change of a stock price in a given time interval is composed of many price changes resulting from single trades. Thus, the up and down movements of a stock price can be seen as analogous to the classic diffusion of a particle: if the particle moves due to random collisions with other particles, the displacement after some time is determined by the sum of the displacements between the collisions. Under certai...

  3. Self-consistent random phase approximation - application to systems of strongly correlated fermions; Approximation des phases aleatoires self-consistante - applications a des systemes de fermions fortement correles

    Energy Technology Data Exchange (ETDEWEB)

    Jemai, M

    2004-07-01

    In the present thesis we have applied the self consistent random phase approximation (SCRPA) to the Hubbard model with a small number of sites (a chain of 2, 4, 6,... sites). Earlier SCRPA had produced very good results in other models like the pairing model of Richardson. It was therefore interesting to see what kind of results the method is able to produce in the case of a more complex model like the Hubbard model. To our great satisfaction the case of two sites with two electrons (half-filling) is solved exactly by the SCRPA. This may seem a little trivial but the fact is that other respectable approximations like 'GW' or the approach with the Gutzwiller wave function yield results still far from exact. With this promising starting point, the case of 6 sites at half filling was considered next. For that case, evidently, SCRPA does not any longer give exact results. However, they are still excellent for a wide range of values of the coupling constant U, covering for instance the phase transition region towards a state with non zero magnetisation. We consider this as a good success of the theory. Non the less the case of 4 sites (a plaquette), as indeed all cases with 4n sites at half filling, turned out to have a problem because of degeneracies at the Hartree Fock level. A generalisation of the present method, including in addition to the pairs, quadruples of Fermions operators (called second RPA) is proposed to also include exactly the plaquette case in our approach. This is therefore a very interesting perspective of the present work. (author)

  4. Interaural bimodal pitch matching with two-formant vowels

    DEFF Research Database (Denmark)

    Guerit, Francois Marie Louis Paul; Chalupper, Josef; Santurette, Sébastien;

    responsible for the large variability of individual bimodal benefit. Therefore, knowledge about the location of the electrode array is an important prerequisite for optimum fitting. Theoretically, the electrode location can be determined from CT-scans. However, these are often not available in audiological...

  5. Interaural bimodal pitch matching with two-formant vowels

    DEFF Research Database (Denmark)

    Guérit, François; Chalupper, Josef; Santurette, Sébastien;

    2013-01-01

    responsible for the large variability of individual bimodal benefit. Therefore, knowledge about the location of the electrode array is an important prerequisite for optimum fitting. Theoretically, the electrode location can be determined from CT-scans. However, these are often not available in audiological...

  6. Bimodal Bilingual Language Development of Hearing Children of Deaf Parents

    Science.gov (United States)

    Hofmann, Kristin; Chilla, Solveig

    2015-01-01

    Adopting a bimodal bilingual language acquisition model, this qualitative case study is the first in Germany to investigate the spoken and sign language development of hearing children of deaf adults (codas). The spoken language competence of six codas within the age range of 3;10 to 6;4 is assessed by a series of standardised tests (SETK 3-5,…

  7. Disturbance Decoupling for Continuous Piecewise Linear Bimodal Systems

    NARCIS (Netherlands)

    Everts, A.R.F.; Camlibel, M.K.

    2014-01-01

    In this paper we tackle the disturbance decoupling problem for continuous bimodal piecewise linear systems. After establishing necessary and sufficient geometric conditions for such a system to be disturbance decoupled, we study state feed- back and dynamic feedback controllers, both mode-dependent

  8. Investigating Interaural Frequency-Place Mismatches via Bimodal Vowel Integration

    DEFF Research Database (Denmark)

    Guérit, François; Santurette, Sébastien; Chalupper, Josef;

    2014-01-01

    For patients having residual hearing in one ear and a cochlear implant (CI) in the opposite ear, interaural place-pitch mismatches might be partly responsible for the large variability in individual benefit. Behavioral pitch-matching between the two ears has been suggested as a way to individuali...... difficulties in bimodal fusion of the two formants....

  9. Bimodal Hearing and Speech Perception with a Competing Talker

    Science.gov (United States)

    Pyschny, Verena; Landwehr, Markus; Hahn, Moritz; Walger, Martin; von Wedel, Hasso; Meister, Hartmut

    2011-01-01

    Purpose: The objective of the study was to investigate the influence of bimodal stimulation upon hearing ability for speech recognition in the presence of a single competing talker. Method: Speech recognition was measured in 3 listening conditions: hearing aid (HA) alone, cochlear implant (CI) alone, and both devices together (CI + HA). To examine…

  10. Measuring oxygen uptake in fishes with bimodal respiration.

    Science.gov (United States)

    Lefevre, S; Bayley, M; McKenzie, D J

    2016-01-01

    Respirometry is a robust method for measurement of oxygen uptake as a proxy for metabolic rate in fishes, and how species with bimodal respiration might meet their demands from water v. air has interested researchers for over a century. The challenges of measuring oxygen uptake from both water and air, preferably simultaneously, have been addressed in a variety of ways, which are briefly reviewed. These methods are not well-suited for the long-term measurements necessary to be certain of obtaining undisturbed patterns of respiratory partitioning, for example, to estimate traits such as standard metabolic rate. Such measurements require automated intermittent-closed respirometry that, for bimodal fishes, has only recently been developed. This paper describes two approaches in enough detail to be replicated by the interested researcher. These methods are for static respirometry. Measuring oxygen uptake by bimodal fishes during exercise poses specific challenges, which are described to aid the reader in designing experiments. The respiratory physiology and behaviour of air-breathing fishes is very complex and can easily be influenced by experimental conditions, and some general considerations are listed to facilitate the design of experiments. Air breathing is believed to have evolved in response to aquatic hypoxia and, probably, associated hypercapnia. The review ends by considering what realistic hypercapnia is, how hypercapnic tropical waters can become and how this might influence bimodal animals' gas exchange. PMID:26358224

  11. SEP BIMOD variable conductance heat pipes acceptance and characterization tests

    Science.gov (United States)

    Hemminger, J. A.

    1981-08-01

    A series of six heat pipes, similar in design to those flown on the Comunications Technology Satellite Hermes, for use in a prototype Solar Electric Propulsion BIMOD thrust module are evaluated. The results of acceptance and characterization tests performed on the heat pipe subassemble are reported. The performance of all the heat pipes met, or exceeded, design specifications.

  12. Does bimodal stimulus presentation increase ERP components usable in BCIs?

    NARCIS (Netherlands)

    Thurlings, M.E.; Brouwer, A.M.; Erp, J.B.F. van; Blankertz, B.; Werkhoven, P.J.

    2012-01-01

    Event-related potential (ERP)-based brain–computer interfaces (BCIs) employ differences in brain responses to attended and ignored stimuli. Typically, visual stimuli are used. Tactile stimuli have recently been suggested as a gaze-independent alternative. Bimodal stimuli could evoke additional brain

  13. Probability of Failure in Random Vibration

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Sørensen, John Dalsgaard

    1988-01-01

    Close approximations to the first-passage probability of failure in random vibration can be obtained by integral equation methods. A simple relation exists between the first-passage probability density function and the distribution function for the time interval spent below a barrier before out-c...... well as for bimodal processes with two dominating frequencies in the structural response....

  14. The bimodality of the Luzon Strait deep water

    Institute of Scientific and Technical Information of China (English)

    WU Qingsong; ZHAO Jianru; ZHANG Junbiao; SHI Weiyong; LIU Chunqiu

    2014-01-01

    Combined conductivity-temperature-depth (CTD) casts and Argo profiles, 3 086 historical hydrocasts were used to quantify the water column characteristics in the northern South China Sea (SCS) and its adjacent waters. Based on a two-dimensional“gravest empirical mode”(GEM), a gravitational potential (׋, a verti-cally integrated variable) was used as proxy for the vertical temperature profiles TG(p,׋).׋integrated from 8 MPa to the surface shows a close relationship with the temperature, except in the deep layer greater than 15 MPa, which was caused by the bimodal deep water in the region. The GEM temperature profiles successfully revealed the bimodality of the Luzon Strait deep water, that disparate hydrophic vertical profiles can pro-duce distinct specific volume anomaly (į) in the SCS and the western Philippine Sea (WPS), but failed in the Luzon Strait, where different temperature profiles may produce a sameį. A significant temperature diver-gence between the SCS water and the WPS water confirmed that the bimodal structure is strong. The deep-water bifurcation starts at about 15 MPa, and gets stronger with increasing depth . As the only deep channel connecting the bimodal-structure waters, water column characteristics in the Luzon Strait is in between, but much closer to the SCS water because of its better connectivity with the SCS. A bimodal temperature structure below 15 MPa reveals that there was a persistent baroclinic pressure gradient driving flow through the Luzon Strait. A volume flux predicted through the Bashi Channel with the hydraulic theory yields a value of 5.62×106 m3/s using all available profiles upstream and downstream of the overflow region, and 4.03×106 and 2.70×106 m3/s by exclusively using the profiles collected during spring and summer, respectively. No volume flux was calculated during autumn and winter because profiles are only available for the upstream of the Bashi Channel during the corresponding period.

  15. 概率可靠多播协议Bimodal Multicast的IOA形式规范%Formal specification of the Bimodal Multicast in IOA

    Institute of Scientific and Technical Information of China (English)

    郭敬林; 刘西洋; 陈平

    2003-01-01

    介绍并讨论了Bimodal Multicast的应用特征和规范形式描述方法,给出了一个基于I/O自动机的描述方案,内容包括Bimodal Multicast中消息的表达,状态和动作的定义,并重点讨论了Bimodal Multicast的最近最先语义的描述方法.

  16. Bimodal Seismic Anisotropy at Cotopaxi volcano (Ecuador): Possible implications

    Science.gov (United States)

    Amin Douillet, Guilhem; Ruiz, Mario; Robin, Claude

    2010-05-01

    A shear wave splitting analysis was performed on Cotopaxi volcano, one of Ecuador most active and hazardous volcanoes, in order to investigate the stress state under this volcano. Cotopaxi volcano is located in a highly populated area including the capital Quito. It's eruptive cycle is approximately 120 ±70 years and apart from possible minor eruptions in 1942 and 1903-1904, the last volcanic activity dates from 1878-1885. Moreover, 15 years of increasing seismicity with some major crisis during the 1995-2010 periods, lead to the current very high seismic level. Finally two years of gas monitoring suggest that the Cotopaxi's emissions are currently intermittent and passive, but non negligible. We analyzed 102 regional tectonic events recorded between 2006 and 2009 at a network of five broad-band three-component seismic stations. These stations are located on all flanks of Cotopaxi. The events used were from several seismic sources located inside a radius of 200 kilometers from the volcano and illuminate all space directions. Seismic events were manually chosen based on their clear shear wave component in regards to the compression wave and to the noise. The data were computed using Matlab software. Polarization directions and delay times of split shear waves were found using a method based on the cross correlation of displacement waveforms of shear-waves at all possible rotation angles. Our results show a bimodal anisotropic behavior. One of the fast-directions axes follows the regional Ecuadorian tectonic general strain with a ESE direction. The other trend was found to be perpendicular to the regional strain. Other studies have shown that a 90° flip may take place either prior, during, or just after the main eruptive phase, or during hydraulic injections. This 90° flip is probably relied to micro cracks filling and pressuring, creating a local reverse strain field. There is not clear trend on temporal evolution of anisotropy distribution on our data. Only one

  17. CN Bimodality at Low Metallicity: The Globular Cluster M53

    CERN Document Server

    Martell, Sarah L; Briley, Michael M

    2007-01-01

    We present low resolution UV-blue spectroscopic observations of red giant stars in the globular cluster M53 ([Fe/H]=-1.84), obtained to study primordial abundance variations and deep mixing via the CN and CH absorption bands. The metallicity of M53 makes it an attractive target: a bimodal distribution of 3883 angstrom CN bandstrength is common in moderate- and high-metallicity globular clusters ([Fe/H] > -1.6) but unusual in those of lower metallicity ([Fe/H] < -2.0). We find that M53 is an intermediate case, and has a broad but not strongly bimodal distribution of CN bandstrength, with CN and CH bandstrengths anticorrelated in the less-evolved stars. Like many other globular clusters, M53 also exhibits a general decline in CH bandstrength and [C/Fe] abundance with rising luminosity on the red giant branch.

  18. Rapid intensification and the bimodal distribution of tropical cyclone intensity

    Science.gov (United States)

    Lee, Chia-Ying; Tippett, Michael K.; Sobel, Adam H.; Camargo, Suzana J.

    2016-02-01

    The severity of a tropical cyclone (TC) is often summarized by its lifetime maximum intensity (LMI), and the climatological LMI distribution is a fundamental feature of the climate system. The distinctive bimodality of the LMI distribution means that major storms (LMI >96 kt) are not very rare compared with less intense storms. Rapid intensification (RI) is the dramatic strengthening of a TC in a short time, and is notoriously difficult to forecast or simulate. Here we show that the bimodality of the LMI distribution reflects two types of storms: those that undergo RI during their lifetime (RI storms) and those that do not (non-RI storms). The vast majority (79%) of major storms are RI storms. Few non-RI storms (6%) become major storms. While the importance of RI has been recognized in weather forecasting, our results demonstrate that RI also plays a crucial role in the TC climatology.

  19. Bimodal Bidding in Experimental All-Pay Auctions

    OpenAIRE

    Christiane Ernst; Christian Thöni

    2013-01-01

    We report results from experimental first-price, sealed-bid, all-pay auctions for a good with a common and known value. We observe bidding strategies in groups of two and three bidders and under two extreme information conditions. As predicted by the Nash equilibrium, subjects use mixed strategies. In contrast to the prediction under standard assumptions, bids are drawn from a bimodal distribution: very high and very low bids are much more frequent than intermediate bids. Standard risk prefer...

  20. Phase diagram of epidemic spreading - unimodal vs. bimodal probability distributions

    OpenAIRE

    Lancic, Alen; Antulov-Fantulin, Nino; Sikic, Mile; Stefancic, Hrvoje

    2009-01-01

    The disease spreading on complex networks is studied in SIR model. Simulations on empirical complex networks reveal two specific regimes of disease spreading: local containment and epidemic outbreak. The variables measuring the extent of disease spreading are in general characterized by a bimodal probability distribution. Phase diagrams of disease spreading for empirical complex networks are introduced. A theoretical model of disease spreading on m-ary tree is investigated both analytically a...

  1. Development of a virtual campus based on bimodal education

    OpenAIRE

    Yábar, J. M.; Añaños, Elena

    2002-01-01

    A bimodal education model is a flexible model which harmoniously combines the possibilities for teaching offered by Information Society Technologies (IST), such as interactive classrooms, videoconference, and the virtual campus, with traditional educational activities such as lectures and certain types of practical training. The main goal was to provide university students and teachers in formal and continuing education with telematic tools based on new information technologies within the fra...

  2. Mobile Education: Towards Affective Bi-modal Interaction for Adaptivity

    Directory of Open Access Journals (Sweden)

    Efthymios Alepis

    2009-04-01

    Full Text Available One important field where mobile technology can make significant contributions is education. However one criticism in mobile education is that students receive impersonal teaching. Affective computing may give a solution to this problem. In this paper we describe an affective bi-modal educational system for mobile devices. In our research we describe a novel approach of combining information from two modalities namely the keyboard and the microphone through a multi-criteria decision making theory.

  3. Fluoride-assisted synthesis of bimodal microporous SSZ-13 zeolite.

    Science.gov (United States)

    Zhu, Xiaochun; Kosinov, Nikolay; Hofmann, Jan P; Mezari, Brahim; Qian, Qingyun; Rohling, Roderigh; Weckhuysen, Bert M; Ruiz-Martínez, Javier; Hensen, Emiel J M

    2016-02-21

    The presence of small amount of fluoride in alkaline hydrothermal synthesis of SSZ-13 zeolite yields bimodal microporous particles with substantially improved performance in the methanol-to-olefins (MTO) reaction. Hydrocarbon uptake measurements and fluorescence microspectroscopy of spent catalysts demonstrate enhanced diffusion through micropores at the grain boundaries of nanocrystals running through the zeolite particles. Fluoride-assisted SSZ-13 synthesis is a cheap and scalable approach to optimize the performance of MTO zeolite catalysts. PMID:26810114

  4. Filtering random matrices: the effect of incomplete channel control in multiple scattering.

    Science.gov (United States)

    Goetschy, A; Stone, A D

    2013-08-01

    We present an analytic random matrix theory for the effect of incomplete channel control on the measured statistical properties of the scattering matrix of a disordered multiple-scattering medium. When the fraction of the controlled input channels, m1, and output channels, m2, is decreased from unity, the density of the transmission eigenvalues is shown to evolve from the bimodal distribution describing coherent diffusion, to the distribution characteristic of uncorrelated Gaussian random matrices, with a rapid loss of access to the open eigenchannels. The loss of correlation is also reflected in an increase in the information capacity per channel of the medium. Our results have strong implications for optical and microwave experiments on diffusive scattering media. PMID:23971574

  5. Sample size calculation for treatment effects in randomized trials with fixed cluster sizes and heterogeneous intraclass correlations and variances.

    Science.gov (United States)

    Candel, Math J J M; van Breukelen, Gerard J P

    2015-10-01

    When comparing two different kinds of group therapy or two individual treatments where patients within each arm are nested within care providers, clustering of observations may occur in both arms. The arms may differ in terms of (a) the intraclass correlation, (b) the outcome variance, (c) the cluster size, and (d) the number of clusters, and there may be some ideal group size or ideal caseload in case of care providers, fixing the cluster size. For this case, optimal cluster numbers are derived for a linear mixed model analysis of the treatment effect under cost constraints as well as under power constraints. To account for uncertain prior knowledge on relevant model parameters, also maximin sample sizes are given. Formulas for sample size calculation are derived, based on the standard normal as the asymptotic distribution of the test statistic. For small sample sizes, an extensive numerical evaluation shows that in a two-tailed test employing restricted maximum likelihood estimation, a safe correction for both 80% and 90% power, is to add three clusters to each arm for a 5% type I error rate and four clusters to each arm for a 1% type I error rate. PMID:25519890

  6. Transconductance bimodal effect of PDSOI submicron H-gate MOSFETs

    Institute of Scientific and Technical Information of China (English)

    Mei Bo; Bi Jinshun; Bu Jianhui; Han Zhengsheng

    2013-01-01

    A bimodal effect of transconductance was observed in narrow channel PDSOI sub-micron H-gate PMOSFETs,which was accompanied with the degeneration of device performance.This paper presents a study of the transconductance bimodal effect based on the manufacturing process and electrical properties of those devices.It is shown that this effect is caused by a diffusion of donor impurities from the N+ region of body contact to the P+ poly gate at the neck of the H-gate,which would change the work function differences of the polysilicon gate and substrate.This means that the threshold voltage of the device is different in the width direction,which means that there are parasitic transistors paralleled with the main transistor at the neck of the H-gate.The subsequent devices were fabricated with layout optimization,and it is demonstrated that the bimodal transconductance can be eliminated by mask modification with N+ implantation more than 0.2μm away from a poly gate.

  7. Frequency-dependent loudness balancing in bimodal cochlear implant users.

    Science.gov (United States)

    Veugen, Lidwien C E; Chalupper, Josef; Snik, Ad F M; van Opstal, A John; Mens, Lucas H M

    2016-08-01

    Conclusion In users of a cochlear implant (CI) and a hearing aid (HA) in contralateral ears, frequency-dependent loudness balancing between devices did, on average, not lead to improved speech understanding as compared to broadband balancing. However, nine out of 15 bimodal subjects showed significantly better speech understanding with either one of the fittings. Objectives Sub-optimal fittings and mismatches in loudness are possible explanations for the large individual differences seen in listeners using bimodal stimulation. Methods HA gain was adjusted for soft and loud input sounds in three frequency bands (0-548, 548-1000, and >1000 Hz) to match loudness with the CI. This procedure was compared to a simple broadband balancing procedure that reflected current clinical practice. In a three-visit cross-over design with 4 weeks between sessions, speech understanding was tested in quiet and in noise and questionnaires were administered to assess benefit in real world. Results Both procedures resulted in comparable HA gains. For speech in noise, a marginal bimodal benefit of 0.3 ± 4 dB was found, with large differences between subjects and spatial configurations. Speech understanding in quiet and in noise did not differ between the two loudness balancing procedures. PMID:26986743

  8. Convergence of the probability of large deviations in a model of correlated random variables having compact-support Q-Gaussians as limiting distributions

    Science.gov (United States)

    Jauregui, Max; Tsallis, Constantino

    2015-02-01

    We consider correlated random variables X1, …, Xn taking values in {0, 1} such that, for any permutation π of {1, …, n}, the random vectors (X1, …, Xn) and (Xπ(1), …, Xπ(n)) have the same distribution. This distribution, which was introduced by Rodríguez et al. [J. Stat. Mech. 2008, P09006] and then generalized by Hanel et al. [Eur. Phys. J. B 72, 263 (2009)], is scale-invariant and depends on a real parameter ν > 0 (ν → ∞ implies independence). Putting Sn = X1 + ⋯ + Xn, the distribution of Sn - n/2 approaches a Q-Gaussian distribution with compact support (Q = 1 - 1/(ν - 1) 0, we show that ℙ(Sn = 0) decays to zero like a power law of the form 1/nν with a subdominant term of the form 1/nν+1. If 0 0 is an integer, we show that we can analytically find upper and lower bounds for the difference between ℙ(Sn/n ≤ x) and its (n → ∞) limit. We also show that these bounds vanish like a power law of the form 1/n with a subdominant term of the form 1/n2.

  9. Frequency characteristic measurement of a fiber optic gyroscope using a correlation spectrum analysis method based on a pseudo-random sequence

    International Nuclear Information System (INIS)

    The frequency characteristic is an important indicator of a system’s dynamic performance. The identification of a fiber optic gyroscope (FOG)’s frequency characteristic using a correlation spectrum analysis method based on a pseudo-random sequence is proposed. Taking the angle vibrator as the source of the test rotation stimulation and a pseudo-random sequence as the test signal, the frequency characteristic of a FOG is calculated according to the power spectral density of the rotation rate signal and the cross-power spectral density of the FOG’s output signal and rotation rate signal. A theoretical simulation is done to confirm the validity of this method. An experiment system is built and the test results indicate that the measurement error of the normalized amplitude–frequency response is less than 0.01, that the error of the phase–frequency response is less than 0.3 rad, and the overall measurement accuracy is superior to the traditional frequency-sweep method. By using this method, the FOG’s amplitude–frequency response and phase–frequency response can be measured simultaneously, quickly, accurately, and with a high frequency resolution. The described method meets the requirements of engineering applications. (paper)

  10. Bimodal quasi-oscillatory and spectral behavior in Scorpius X-1

    Science.gov (United States)

    Priedhorsky, W.; Hasinger, G.; Lewin, W. H. G.; Middleditch, J.; Parmar, A.

    1986-01-01

    Exosat observations of Sco X-1 obtained using the Xe and/or Ar detectors for a total of about 80,000 s during four runs on August 24-27, 1985 are reported and analyzed. Two modes of quasi-periodic oscillations (QPOs) corresponding to the quiescent and active states of Sco X-1 and to two modes of spectral behavior are identified and characterized, confirming the findings of Priedhorsky (1985) and Middleditch and Priedhorsky (1986). In the quiescent state, the QPO frequency is about 6 Hz and is anticorrelated with intensity, and the spectral hardness ratio (14-21 vs 2-7 keV) varies steeply with intensity; in the active state, QPO frequency is correlated with intensity and varies from 10 to 20 Hz, and the spectral-hardness-ratio/intensity curve is flatter. Previous observations of bimodal behavior in other bands are summarized, and theoretical models proposed to explain them are discussed.

  11. Origin of bimodal fluorescence enhancement factors of Chlorobaculum tepidum reaction centers on silver island films.

    Science.gov (United States)

    Maćkowski, Sebastian; Czechowski, Nikodem; Ashraf, Khuram U; Szalkowski, Marcin; Lokstein, Heiko; Cogdell, Richard J; Kowalska, Dorota

    2016-08-01

    We focus on the spectral dependence of plasmon-induced enhancement of fluorescence of Chlorobaculum tepidum reaction centers. When deposited on silver island film, they exhibit up to a 60-fold increase in fluorescence. The dependence of enhancement factors on the excitation wavelength is not correlated with the absorption spectrum of the plasmonic structure. In particular, the presence of one (or multiple) trimers of the Fenna-Matthews-Olson (FMO) protein reveals itself in bimodal distribution of enhancement factors for the excitation at 589 nm, the wavelength corresponding to bacteriochlorophyll absorption of FMO and the core of the RC. We conclude that the structure of multichromophoric complexes can substantially affect the impact of plasmonic excitations, which is important in the context of assembling functional biohybrid systems. PMID:27406896

  12. Bimodal bilingualism as multisensory training?: Evidence for improved audiovisual speech perception after sign language exposure.

    Science.gov (United States)

    Williams, Joshua T; Darcy, Isabelle; Newman, Sharlene D

    2016-02-15

    The aim of the present study was to characterize effects of learning a sign language on the processing of a spoken language. Specifically, audiovisual phoneme comprehension was assessed before and after 13 weeks of sign language exposure. L2 ASL learners performed this task in the fMRI scanner. Results indicated that L2 American Sign Language (ASL) learners' behavioral classification of the speech sounds improved with time compared to hearing nonsigners. Results indicated increased activation in the supramarginal gyrus (SMG) after sign language exposure, which suggests concomitant increased phonological processing of speech. A multiple regression analysis indicated that learner's rating on co-sign speech use and lipreading ability was correlated with SMG activation. This pattern of results indicates that the increased use of mouthing and possibly lipreading during sign language acquisition may concurrently improve audiovisual speech processing in budding hearing bimodal bilinguals. PMID:26740404

  13. Gaze-independent ERP-BCIs: augmenting performance through location-congruent bimodal stimuli

    OpenAIRE

    Marieke Elise Thurlings; Anne-Marie eBrouwer; Van Erp, Jan B.F.; Peter eWerkhoven

    2014-01-01

    Gaze-independent event-related potential (ERP) based brain-computer interfaces (BCIs) yield relatively low BCI performance and traditionally employ unimodal stimuli. Bimodal ERP-BCIs may increase BCI performance due to multisensory integration or summation in the brain. An additional advantage of bimodal BCIs may be that the user can choose which modality or modalities to attend to. We studied bimodal, visual-tactile, gaze-independent BCIs and investigated whether or not ERP components’ tAUCs...

  14. Bimodal PE prepared with combined iron Ⅱ and nickel Ⅱ olefin polymerization catalysts

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Combined iron Ⅱ and nickel Ⅱ olefin polymerization catalysts could produce a kind of PE having the characters of ideal bimodal PE with appropriate conditions and catalysts. In the ethylene homopolymerization with triethylalkylaluminum (AlEt3) as the activator, the prepared bimodal PE contained not only branched PE of high molecular weight, but also linear PE of low molecular weight. And the amounts of both fractions were similar. Ideal bimodal PE resin was prepared in one polymerization reactor.

  15. Bimodal Benefits on Objective and Subjective Outcomes for Adult Cochlear Implant Users

    OpenAIRE

    Heo, Ji-Hye; Lee, Jae-Hee; Lee, Won-Sang

    2013-01-01

    Background and Objectives Given that only a few studies have focused on the bimodal benefits on objective and subjective outcomes and emphasized the importance of individual data, the present study aimed to measure the bimodal benefits on the objective and subjective outcomes for adults with cochlear implant. Subjects and Methods Fourteen listeners with bimodal devices were tested on the localization and recognition abilities using environmental sounds, 1-talker, and 2-talker speech materials...

  16. Gaze-independent ERP-BCIs : Augmenting performance through location-congruent bimodal stimuli

    OpenAIRE

    Thurlings, Marieke E.; Brouwer, Anne-Marie; Van Erp, Jan B.F.; Werkhoven, Peter

    2014-01-01

    Gaze-independent event-related potential (ERP) based brain-computer interfaces (BCIs) yield relatively low BCI performance and traditionally employ unimodal stimuli. Bimodal ERP-BCIs may increase BCI performance due to multisensory integration or summation in the brain. An additional advantage of bimodal BCIs may be that the user can choose which modality or modalities to attend to. We studied bimodal, visual-tactile, gaze-independent BCIs and investigated whether or not ERP components’ tAUCs...

  17. On the existence of hysteresis in the Kuramoto model with bimodal frequency distributions

    OpenAIRE

    Montbrió, Ernest; Pazó, Diego

    2009-01-01

    We investigate the transition to synchronization in the Kuramoto model with bimodal distributions of the natural frequencies. Previous studies have concluded that the model exhibits a hysteretic phase transition if the bimodal distribution is close to a unimodal one, due to the shallowness the central dip. Here we show that proximity to the unimodal-bimodal border does not necessarily imply hysteresis when the width, but not the depth, of the central dip tends to zero. We draw this conclusio...

  18. Existence of hysteresis in the Kuramoto model with bimodal frequency distributions

    OpenAIRE

    Pazó, Diego; Montbrió, Ernest

    2009-01-01

    We investigate the transition to synchronization in the Kuramoto model with bimodal distributions of the natural frequencies. Previous studies have concluded that the model exhibits a hysteretic phase transition if the bimodal distribution is close to a unimodal one, due to the shallowness the central dip. Here we show that proximity to the unimodal-bimodal border does not necessarily imply hysteresis when the width, but not the depth, of the central dip tends to zero. We draw this conclusion...

  19. Transition for Optimal Paths in Bimodal Directed Polymers

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Hong

    2005-01-01

    @@ The problem for optimal paths in bimodal directed polymers is studied. It is shown that the distribution of the thermal average position of the endpoints of the optimal paths is discontinuous below the threshold p < pc. The origin is that there is a finite possibility that only one endpoint takes the global minimum energy for p < pc. Our results suggest that the percolation threshold for directed percolation is also the critical point of the transition for the possibility that the optimal paths converge to one endpoint.

  20. CN Bimodality at Low Metallicity: The Globular Cluster M53

    OpenAIRE

    Martell, Sarah L.; Smith, Graeme H.; Briley, Michael M.

    2007-01-01

    We present low resolution UV-blue spectroscopic observations of red giant stars in the globular cluster M53 ([Fe/H]=-1.84), obtained to study primordial abundance variations and deep mixing via the CN and CH absorption bands. The metallicity of M53 makes it an attractive target: a bimodal distribution of 3883 angstrom CN bandstrength is common in moderate- and high-metallicity globular clusters ([Fe/H] > -1.6) but unusual in those of lower metallicity ([Fe/H] < -2.0). We find that M53 is an i...

  1. Phase diagram of epidemic spreading - unimodal vs. bimodal probability distributions

    CERN Document Server

    Lancic, Alen; Sikic, Mile; Stefancic, Hrvoje

    2009-01-01

    The disease spreading on complex networks is studied in SIR model. Simulations on empirical complex networks reveal two specific regimes of disease spreading: local containment and epidemic outbreak. The variables measuring the extent of disease spreading are in general characterized by a bimodal probability distribution. Phase diagrams of disease spreading for empirical complex networks are introduced. A theoretical model of disease spreading on m-ary tree is investigated both analytically and in simulations. It is shown that the model reproduces qualitative features of phase diagrams of disease spreading observed in empirical complex networks. The role of tree-like structure of complex networks in disease spreading is discussed.

  2. Bimodal fission in the Skyrme-Hartree-Fock approach

    OpenAIRE

    Staszczak, A.; Dobaczewski, J.; Nazarewicz, W.

    2006-01-01

    Spontaneous-fission properties of 256Fm, 258Fm, and 260Fm isotopes are studied within the Skyrme-Hartree-Fock+BCS framework. In the particle-hole channel we take the Skyrme SkM* effective force, while in the particle-particle channel we employ the seniority pairing interaction. Three static fission paths for all investigated heavy fermium isotopes are found. The analysis of these fission modes allows to describe observed asymmetric fission of 256Fm, as well as bimodal fission of 258Fm and sym...

  3. Effect of Strength Training on Oxidative Stress and the Correlation of the Same with Forearm Vasodilatation and Blood Pressure of Hypertensive Elderly Women: A Randomized Clinical Trial

    Science.gov (United States)

    Dantas, Filipe Fernandes Oliveira; Batista, Rafael Marinho Falcão; do Nascimento, Leone Severino; Castellano, Lúcio Roberto Cançado; Ritti-Dias, Raphael Mendes; Lima, Kenio Costa

    2016-01-01

    The aim of the study was to evaluate the effect of strength training on oxidative stress and the correlation of the same with forearm vasodilatation and mean blood pressure of hypertensive elderly women, at rest (basal) and during a static handgrip exercise. Insufficiently active hypertensive elderly women (N = 25; mean age = 66.1 years) were randomized into a 10 week strength training group (n = 13) or control (n = 12) group. Plasma malondialdehyde (MDA), total antioxidant capacity (TAC), plasma nitrite (NO2-), forearm blood flow (FBF), mean blood pressure (MBP) and vascular conductance ([FBF / MBP] x 100) were evaluated before and after the completion of the interventions. The strength training group increased the TAC (pre: Median = 39.0; Interquartile range = 34.0–41.5% vs post: Median = 44.0; Interquartile range = 38.0–51.5%; p = 0.006) and reduced the MDA (pre: 4.94 ± 1.10 μM vs post: 3.90 ± 1.35 μM; p = 0.025; CI-95%: -1.92 –-0.16 μM). The strength training group increased basal vascular conductance (VC) (pre: 3.56 ±0.88 units vs post: 5.21 ±1.28 units; p = 0.001; CI-95%: 0.93–2.38 units) and decreased basal MBP (pre: 93.1 ±6.3 mmHg vs post: 88.9 ±5.4 mmHg; p = 0.035; CI-95%: -8.0 –-0.4 mmHg). Such changes were also observed during static handgrip exercise. A moderate correlation was observed between changes in basal VC and MBP with changes in NO2- (ΔVC → r = -0.56, p = 0.047; ΔMBP → r = -0.41, p = 0.168) and MDA (ΔVC → r = 0.64, p = 0.019; ΔMBP → r = 0.31, p = 0.305). The strength training program reduced the oxidative stress of the hypertensive elderly women and this reduction was moderately correlated with their cardiovascular benefits. Trial Registration: ensaiosclinicos.gov.br RBR-48c29w PMID:27529625

  4. Bimodal distribution of glucose is nog universally useful for diagnosing diabetes

    NARCIS (Netherlands)

    Vistisen, D.; Colagiuri, S.; Borch-Johnsen, K.

    2009-01-01

    OBJECTIVE—Bimodality in the distribution of glucose has been used to define the cut point for the diagnosis of diabetes. Previous studies on bimodality have primarily been in populations with a high prevalence of type 2 diabetes, including one study in a white Caucasian population. All studies inclu

  5. Gaze-independent ERP-BCIs: augmenting performance through location-congruent bimodal stimuli

    Science.gov (United States)

    Thurlings, Marieke E.; Brouwer, Anne-Marie; Van Erp, Jan B. F.; Werkhoven, Peter

    2014-01-01

    Gaze-independent event-related potential (ERP) based brain-computer interfaces (BCIs) yield relatively low BCI performance and traditionally employ unimodal stimuli. Bimodal ERP-BCIs may increase BCI performance due to multisensory integration or summation in the brain. An additional advantage of bimodal BCIs may be that the user can choose which modality or modalities to attend to. We studied bimodal, visual-tactile, gaze-independent BCIs and investigated whether or not ERP components’ tAUCs and subsequent classification accuracies are increased for (1) bimodal vs. unimodal stimuli; (2) location-congruent vs. location-incongruent bimodal stimuli; and (3) attending to both modalities vs. to either one modality. We observed an enhanced bimodal (compared to unimodal) P300 tAUC, which appeared to be positively affected by location-congruency (p = 0.056) and resulted in higher classification accuracies. Attending either to one or to both modalities of the bimodal location-congruent stimuli resulted in differences between ERP components, but not in classification performance. We conclude that location-congruent bimodal stimuli improve ERP-BCIs, and offer the user the possibility to switch the attended modality without losing performance. PMID:25249947

  6. The Randomized Dependence Coefficient

    OpenAIRE

    Lopez-Paz, David; Hennig, Philipp; Schölkopf, Bernhard

    2013-01-01

    We introduce the Randomized Dependence Coefficient (RDC), a measure of non-linear dependence between random variables of arbitrary dimension based on the Hirschfeld-Gebelein-R\\'enyi Maximum Correlation Coefficient. RDC is defined in terms of correlation of random non-linear copula projections; it is invariant with respect to marginal distribution transformations, has low computational cost and is easy to implement: just five lines of R code, included at the end of the paper.

  7. 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.

  8. Parametric Analysis of Tensile Properties of Bimodal Al Alloys by Finite Element Method

    Institute of Scientific and Technical Information of China (English)

    W.L. Zhanga; S. Li; S.R. Nutt

    2009-01-01

    An axisymmetrical unit cell model was used to represent a bimodal Al alloy that was composed of both nano-grained (NG) and coarse-grained (CG) aluminum. Effects of microstructural and materials parameters on tensile properties of bimodal Al alloy were investigated by finite element method (FEM). The parameters analyzed included aspect ratios of CG Al and the unit cell, volume fraction of CG Al (VFCG), and yield strength and strain hardening exponent of CG Al. Aspect ratios of CG Al and the unit cell have no significant influence on tensile stress-strain response of the bimodal Al alloy. This phenomenon derives from the similarity in elastic modulus and coefficient of thermal expansion between CG Al and NG Al. Conversely, tensile properties of bimodal Al alloy are extremely sensitive to VFCG, yield strength and strain hardening exponent of CG Al.Specifically, as VFCG increases, both yield strength and ultimate tensile strength (UTS) of the bimodal Al alloy decreases, while uniform strain of bimodal Al alloy increases. In addition, an increase in yield strength of CG Al results in an increase in both yield stress and UTS of bimodal Al alloy and a decrease in uniform strain of bimodal Al alloy. The lower capability in lowering the increase of stress concentration in NG Al due to a higher yield strength of CG Al causes the lower uniform strain of the bimodal Al alloy. When strain hardening exponent of CG Al increases, 0.2% yield stress, UT5, and uniform strain of the bimodal Al alloy increases. This can be attributed to the increased work-hardening ability of CG Al with a higher strain hardening exponent.

  9. The case against bimodal star formation in elliptical galaxies

    CERN Document Server

    Gibson, B K

    1995-01-01

    We consider the present-day photometric and chemical properties of elliptical galaxies, adopting the bimodal star formation scenario of Elbaz, Arnaud & Vangioni-Flam (1995). These models utilise an initial mass function (IMF) biased heavily toward massive stars during the early phases of galactic evolution, leading to early Type II supernovae-driven galactic winds. A subsequent lengthy, milder, star formation phase with a normal IMF ensues, responsible supposedly for the stellar population observed today. Based upon chemical evolution arguments alone, this scenario has been invoked to explain the observed metal mass, and their abundance ratios, in the intracluster medium of galaxy clusters. Building upon the recent compilations of metallicity-dependent isochrones for simple stellar populations, we have constructed a coupled photometric and chemical evolution package for composite stellar populations in order to quantify the effects of such a model upon the photo-chemical properties of the resultant ellipt...

  10. METALLOCENE POLYETHYLENES WITH BROAD OR BIMODAL MOLECULAR WEIGHT DISTRIBUTION

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Seven new binuclear titanocenes with different linking bridges, unsubstituted or substituted on the Cp rings, were synthesized and tested for their effect on ethylene polymerization in the presence of MAO. The polyethylenes thus obtained had broad MWD or even bimodal GPC curves, as compared with that from two reference mononuclear titanocenes. This is explained by the difference in degree of steric hindrance around the active center sites imposed by the bulky substituted ligands assuming different configurations in the rotation of the catalyst molecules. Lower polymerization temperatures alleviate the effect of these configuration differences, as reflected in change in MW and -Mw/-Mn. This effect is not caused by decomposition or disproportionation of the binuclear titanocenes as evidenced by the stability of the catalyst.

  11. Steady bimodal convection in a cylinder at large Prandtl numbers

    Science.gov (United States)

    Buell, Jeffrey C.; Catton, Ivan

    1987-01-01

    Steady bimodal convection of an infinite Prandtl-number Boussinesq fluid in a cylinder is considered. An asymptotic analysis similar to the one used by Buell and Catton (1986) for axisymmetric convection yields a solvability condition that determines the radial wavenumber. The analysis is valid for convection far away from the origin, the lateral boundary, and any pattern dislocations. The azimuthal wave number is treated as a parameter, although in real systems it is dependent on the initial and boundary conditions. Results are presented for Rayleigh numbers between 14,000 and 60,000, and for azimuthal wave numbers between 5 and 7. It is shown that for increasing Rayleigh numbers, the selected radial wave number and the heat transfer tend to become independent of the azimuthal wave number. No quantitative experimental data are available, but one qualitative comparison is good.

  12. Progress in Bimodal Polyethylene Produced by Metallocene Catalyst

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ The external new ways, kinds and recant advances of bimodal Polyethylene produced by metallocene catalyst were reviewed. For example, U.S.Pat.No 4939217 discloses an olefin polymerization supported catalyst comprising at least two different metallocenes each having different olefin polymerization termination rate constants in the presence of hydrogen. U.S.Pat. No.5077255 discloses an olefin polymerization supported catalyst comprising at least one metallocene of a metal, a non-metallocene transition metal and an alumoxane. The supported product is highly useful for the polymerization of olefins especially ethylene and especially for the copolymerization of ethylene and other mono and diolefins. U.S.Pat.No.5986024 discloses a process is provided for preparing polymer compositions which are multimodal in nature. The process involves contacting, under polymerization conditions, a selected addition polymerizable monomer with a metallocene catalyst having two or more distinct and chemically different active sites, and a catalyst activator.

  13. Progress in Bimodal Polyethylene Produced by Metallocene Catalyst

    Institute of Scientific and Technical Information of China (English)

    FENG; YuTao

    2001-01-01

    The external new ways, kinds and recant advances of bimodal Polyethylene produced by metallocene catalyst were reviewed. For example, U.S.Pat.No 4939217 discloses an olefin polymerization supported catalyst comprising at least two different metallocenes each having different olefin polymerization termination rate constants in the presence of hydrogen. U.S.Pat. No.5077255 discloses an olefin polymerization supported catalyst comprising at least one metallocene of a metal, a non-metallocene transition metal and an alumoxane. The supported product is highly useful for the polymerization of olefins especially ethylene and especially for the copolymerization of ethylene and other mono and diolefins. U.S.Pat.No.5986024 discloses a process is provided for preparing polymer compositions which are multimodal in nature. The process involves contacting, under polymerization conditions, a selected addition polymerizable monomer with a metallocene catalyst having two or more distinct and chemically different active sites, and a catalyst activator.  ……

  14. More stable yet bimodal geodynamo during the Cretaceous superchron?

    Science.gov (United States)

    Lhuillier, Florian; Gilder, Stuart A.; Wack, Michael; He, Kuang; Petersen, Nikolai; Singer, Brad S.; Jicha, Brian R.; Schaen, Allen J.; Colon, Dylan

    2016-06-01

    We report palaeomagnetic and 40Ar/39Ar dating results from two sequences of basaltic lava flows deposited at the same locality in western China, yet separated in time by ~50 Myr: one set lies within the Cretaceous normal superchron at 112-115 Ma and a second at 59-70 Ma spanning the Cretaceous-Palaeogene boundary. We find that magnetic field directions during the superchron exhibit bimodal populations: one with inclinations representative of a dipolar field and another with shallow inclinations that could reflect a more complex, multipolar field. However, the time-dependent variability in field directions was 50% lower during the superchron than after, which implies greater field stability during the superchron. Our results suggest that episodes of less dipolar field behavior occurred within the Cretaceous superchron and raise the question whether a second, more multipolar, field state is more persistent than previously thought.

  15. Bimodal star formation - Constraints from the solar neighborhood

    Science.gov (United States)

    Wyse, Rosemary F. G.; Silk, J.

    1987-01-01

    The chemical evolution resulting from a simple model of bimodal star formulation is investigated, using constraints from the solar neighborhood to set the parameters of the initial mass function and star formation rate. The two modes are an exclusively massive star mode, which forms stars at an exponentially declining rate, and a mode which contains stars of all masses and has a constant star formation rate. Satisfactory agreement with the age-metallicity relation for the thin disk and with the metallicity structure of the thin-disk and spheroid stars is possible only for a small range of parameter values. The preferred model offers a resolution to several of the long-standing problems of galactic chemical evolution, including explanations of the age-metallicity relation, the gas consumption time scale, and the stellar cumulative metallicity distributions.

  16. Template synthesis of 3-D bimodal ordered porous silica

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A dual template synthesis combined with a modified bulk sol-gel process was used to prepare the three dimensional bimodal ordered porous silica, in which the macropore wall is mesoporous and both the pores are interconnected. The macropores were replicated from the template of the dried polystyrene colloidal crystal after being removed by calcination at high temperature, whislt the mesopores were achieved by burning off the surfactant in the gel. The ordered morphologies and interconnection of both the macropores and the mesopores were evidenced by the characterizations with SEM and TEM attached with electron diffraction. Nitrogen adsorption results also confirmed the interconnectivity, sizes and their distribution of the two sorts of pores. The effect of surfactant concentration and calcination conditions on mesopore size and its distribution was also investigated.

  17. AGN Feedback and Bimodality in Cluster Core Entropy

    CERN Document Server

    Guo, Fulai; Ruszkowski, M

    2009-01-01

    We investigate a series of steady-state models of galaxy clusters, in which the hot intracluster gas is efficiently heated by active galactic nucleus (AGN) feedback and thermal conduction, and in which the mass accretion rates are highly reduced compared to those predicted by the standard cooling flow models. We perform a global Lagrangian stability analysis. We show for the first time that the global radial instability in cool core clusters can be suppressed by the AGN feedback mechanism, provided that the feedback efficiency exceeds a critical lower limit. Furthermore, our analysis naturally shows that the clusters can exist in two distinct forms. Globally stable clusters are expected to have either: 1) cool cores stabilized by both AGN feedback and conduction, or 2) non-cool cores stabilized primarily by conduction. Intermediate central temperatures typically lead to globally unstable solutions. This bimodality is consistent with the recently observed anticorrelation between the flatness of the temperature...

  18. Co-Localized or Randomly Distributed? Pair Cross Correlation of In Vivo Grown Subgingival Biofilm Bacteria Quantified by Digital Image Analysis

    Science.gov (United States)

    Lux, Renate; Riep, Birgit; Kikhney, Judith; Friedmann, Anton; Wolinsky, Lawrence E.; Göbel, Ulf B.; Daims, Holger; Moter, Annette

    2012-01-01

    The polymicrobial nature of periodontal diseases is reflected by the diversity of phylotypes detected in subgingival plaque and the finding that consortia of suspected pathogens rather than single species are associated with disease development. A number of these microorganisms have been demonstrated in vitro to interact and enhance biofilm integration, survival or even pathogenic features. To examine the in vivo relevance of these proposed interactions, we extended the spatial arrangement analysis tool of the software daime (digital image analysis in microbial ecology). This modification enabled the quantitative analysis of microbial co-localization in images of subgingival biofilm species, where the biomass was confined to fractions of the whole-image area, a situation common for medical samples. Selected representatives of the disease-associated red and orange complexes that were previously suggested to interact with each other in vitro (Tannerella forsythia with Fusobacterium nucleatum and Porphyromonas gingivalis with Prevotella intermedia) were chosen for analysis and labeled with specific fluorescent probes via fluorescence in situ hybridization. Pair cross-correlation analysis of in vivo grown biofilms revealed tight clustering of F. nucleatum/periodonticum and T. forsythia at short distances (up to 6 µm) with a pronounced peak at 1.5 µm. While these results confirmed previous in vitro observations for F. nucleatum and T. forsythia, random spatial distribution was detected between P. gingivalis and P. intermedia in the in vivo samples. In conclusion, we successfully employed spatial arrangement analysis on the single cell level in clinically relevant medical samples and demonstrated the utility of this approach for the in vivo validation of in vitro observations by analyzing statistically relevant numbers of different patients. More importantly, the culture-independent nature of this approach enables similar quantitative analyses for

  19. Proposal of bimodal solution for urban vehicular contamination problem

    Directory of Open Access Journals (Sweden)

    Gilberto Osorio Gómez

    2010-04-01

    Full Text Available In research field of alternative solutions to internal combustion engine vehicles, the Politecnico di Milano has developed a design and manufacturing project for an adaptable electro-mechanical kit intended to transform a city car with en-dothermic propulsion into a bimodal one, using existent technologies and innovative solutions. This project involves mechanical and electrical competences in order to develop a new transmission parallel to the current endothermic propulsion and its control system. This paper describes, in general, the developed procedure to obtain the final proto-type. At first, the requirements and constraints to fulfil a standard transport urban cycle has been established and the vehicle to modify was selected, in this case the Fiat Grande Punto. Next, new components and the required space to their installation have been identified and specified, whilst mechanical components were designed and manufactured. Instruments of reverse engineering and virtual prototyping have been employed to carry out the geometrical models, simulations and layouts and to identify useful spaces in the vehicle. Finally, general modifications, installation of new components, implementation of control and data acquisition system, fine-tuning and check of specifications fulfilment have been carried out. A 30 km range working in electrical mode, with a top speed of 70 km/h, is assured with the developed kit. These results demonstrate the feasibility to implement a forward bimodal propulsion system into a com-mercial city car with a little invasive commercial kit, and now, the Politecnico is working at its industrialization and im-plementation to different models of city cars. Regione Lombardia (Regional government in Italy has funded this project as an investigation oriented to find new solutions to sustainable transport and reduction of environmental pollution.

  20. Intensity fluctuations in bimodal micropillar lasers enhanced by quantum-dot gain competition

    Science.gov (United States)

    Leymann, H. A. M.; Hopfmann, C.; Albert, F.; Foerster, A.; Khanbekyan, M.; Schneider, C.; Höfling, S.; Forchel, A.; Kamp, M.; Wiersig, J.; Reitzenstein, S.

    2013-05-01

    We investigate correlations between orthogonally polarized cavity modes of a bimodal micropillar laser with a single layer of self-assembled quantum dots in the active region. While one emission mode of the microlaser demonstrates a characteristic S-shaped input-output curve, the output intensity of the second mode saturates and even decreases with increasing injection current above threshold. Measuring the photon autocorrelation function g(2)(τ) of the light emission confirms the onset of lasing in the first mode with g(2)(0) approaching unity above threshold. In contrast, strong photon bunching associated with superthermal values of g(2)(0) is detected for the other mode for currents above threshold. This behavior is attributed to gain competition of the two modes induced by the common gain material, which is confirmed by photon cross-correlation measurements revealing a clear anticorrelation between emission events of the two modes. The experimental studies are in qualitative agreement with theoretical studies based on a microscopic semiconductor theory, which we extend to the case of two modes interacting with the common gain medium. Moreover, we treat the problem by a phenomenological birth-death model extended to two interacting modes, which reveals that the photon probability distribution of each mode has a double-peak structure, indicating switching behavior of the modes for pump rates around threshold.

  1. An effective inversion algorithm for retrieving bimodal aerosol particle size distribution from spectral extinction data

    International Nuclear Information System (INIS)

    The Ant Colony Optimization algorithm based on the probability density function (PDF-ACO) is applied to estimate the bimodal aerosol particle size distribution (PSD). The direct problem is solved by the modified Anomalous Diffraction Approximation (ADA, as an approximation for optically large and soft spheres, i.e., χ⪢1 and |m−1|⪡1) and the Beer–Lambert law. First, a popular bimodal aerosol PSD and three other bimodal PSDs are retrieved in the dependent model by the multi-wavelength extinction technique. All the results reveal that the PDF-ACO algorithm can be used as an effective technique to investigate the bimodal PSD. Then, the Johnson's SB (J-SB) function and the modified beta (M-β) function are employed as the general distribution function to retrieve the bimodal PSDs under the independent model. Finally, the J-SB and M-β functions are applied to recover actual measurement aerosol PSDs over Beijing and Shanghai obtained from the aerosol robotic network (AERONET). The numerical simulation and experimental results demonstrate that these two general functions, especially the J-SB function, can be used as a versatile distribution function to retrieve the bimodal aerosol PSD when no priori information about the PSD is available. - Highlights: • Bimodal PSDs are retrieved by ACO based on probability density function accurately. • J-SB and M-β functions can be used as the versatile function to recover bimodal PSDs. • Bimodal aerosol PSDs can be estimated by J-SB function more reasonably

  2. MMP1 bimodal expression and differential response to inflammatory mediators is linked to promoter polymorphisms

    Directory of Open Access Journals (Sweden)

    Print Cristin G

    2011-01-01

    Full Text Available Abstract Background Identifying the functional importance of the millions of single nucleotide polymorphisms (SNPs in the human genome is a difficult challenge. Therefore, a reverse strategy, which identifies functionally important SNPs by virtue of the bimodal abundance across the human population of the SNP-related mRNAs will be useful. Those mRNA transcripts that are expressed at two distinct abundances in proportion to SNP allele frequency may warrant further study. Matrix metalloproteinase 1 (MMP1 is important in both normal development and in numerous pathologies. Although much research has been conducted to investigate the expression of MMP1 in many different cell types and conditions, the regulation of its expression is still not fully understood. Results In this study, we used a novel but straightforward method based on agglomerative hierarchical clustering to identify bimodally expressed transcripts in human umbilical vein endothelial cell (HUVEC microarray data from 15 individuals. We found that MMP1 mRNA abundance was bimodally distributed in un-treated HUVECs and showed a bimodal response to inflammatory mediator treatment. RT-PCR and MMP1 activity assays confirmed the bimodal regulation and DNA sequencing of 69 individuals identified an MMP1 gene promoter polymorphism that segregated precisely with the MMP1 bimodal expression. Chromatin immunoprecipation (ChIP experiments indicated that the transcription factors (TFs ETS1, ETS2 and GATA3, bind to the MMP1 promoter in the region of this polymorphism and may contribute to the bimodal expression. Conclusions We describe a simple method to identify putative bimodally expressed RNAs from transcriptome data that is effective yet easy for non-statisticans to understand and use. This method identified bimodal endothelial cell expression of MMP1, which appears to be biologically significant with implications for inflammatory disease. (271 Words

  3. Bimodal distribution of RNA expression levels in human skeletal muscle tissue

    Directory of Open Access Journals (Sweden)

    Krakoff Jonathan

    2011-02-01

    Full Text Available Abstract Background Many human diseases and phenotypes are related to RNA expression, levels of which are influenced by a wide spectrum of genetic and exposure-related factors. In a large genome-wide study of muscle tissue expression, we found that some genes exhibited a bimodal distribution of RNA expression, in contrast to what is usually assumed in studies of a single healthy tissue. As bimodality has classically been considered a hallmark of genetic control, we assessed the genome-wide prevalence, cause, and association of this phenomenon with diabetes-related phenotypes in skeletal muscle tissue from 225 healthy Pima Indians using exon array expression chips. Results Two independent batches of microarrays were used for bimodal assessment and comparison. Of the 17,881 genes analyzed, eight (GSTM1, HLA-DRB1, ERAP2, HLA-DRB5, MAOA, ACTN3, NR4A2, and THNSL2 were found to have bimodal expression replicated in the separate batch groups, while 24 other genes had evidence of bimodality in only one group. Some bimodally expressed genes had modest associations with pre-diabetic phenotypes, of note ACTN3 with insulin resistance. Most of the other bimodal genes have been reported to be involved with various other diseases and characteristics. Association of expression with cis genetic variation in a subset of 149 individuals found all but one of the confirmed bimodal genes and nearly half of all potential ones to be highly significant expression quantitative trait loci (eQTL. The rare prevalence of these bimodally expressed genes found after controlling for batch effects was much lower than the prevalence reported in other studies. Additional validation in data from separate muscle expression studies confirmed the low prevalence of bimodality we observed. Conclusions We conclude that the prevalence of bimodal gene expression is quite rare in healthy muscle tissue (cis-polymorphisms, indicating that such bimodal genes are, for the most part, eQTL. The

  4. Bimodal zone of the soil textural triangle : common in tropical and subtropical regions

    OpenAIRE

    Condappa, D. De; Galle, Sylvie; Dewandel, B.; Haverkamp, Randel

    2008-01-01

    The USDA soil textural triangle shows a zone where sods have a low silt fraction compared with the fractions of sand and day. These soils have a particle-size distribution function showing two local maxima in weight percentage for the particle-size ranges of sand and clay. The soils are referred to as bimodal soil, with an associated bimodal zone in the soil textural triangle. It was shown that processes of pedogenesis in tropical and subtropical regions favor the generation of bimodal soils....

  5. Bi-modal Structure of Copper via Room-Temperature Partial Recrystallization After Cryogenic Dynamic Compression

    Science.gov (United States)

    Ahn, Dong-Hyun; Lee, Dong Jun; Kang, Minju; Park, Lee Ju; Lee, Sunghak; Kim, Hyoung Seop

    2016-04-01

    P ure copper was compressed at high strain rates (over ~3 × 103 s-1) under liquid nitrogen. This deformation resulted in bi-modal microstructures of ultrafine grains and abnormally grown micro grains, and in greater hardness (by ~30 Hv) than room-temperature, dynamically deformed copper. This bi-modal microstructure is attributable to partial recrystallization at room temperature, activated by high-energy states and by twins generated at high Zener-Hollomon parameter conditions. This result demonstrates a new approach for producing bi-modally structured materials.

  6. Bi-modal G\\"odel logic over [0,1]-valued Kripke frames

    CERN Document Server

    Caicedo, Xavier

    2011-01-01

    We consider the G\\"odel bi-modal logic determined by fuzzy Kripke models where both the propositions and the accessibility relation are infinitely valued over the standard G\\"odel algebra [0,1] and prove strong completeness of Fischer Servi intuitionistic modal logic IK plus the prelinearity axiom with respect to this semantics. We axiomatize also the bi-modal analogues of $T,$ $S4,$ and $S5$ obtained by restricting to models over frames satisfying the [0,1]-valued versions of the structural properties which characterize these logics. As application of the completeness theorems we obtain a representation theorem for bi-modal G\\"odel algebras.

  7. On Gaussian random supergravity

    International Nuclear Information System (INIS)

    We study the distribution of metastable vacua and the likelihood of slow roll inflation in high dimensional random landscapes. We consider two examples of landscapes: a Gaussian random potential and an effective supergravity potential defined via a Gaussian random superpotential and a trivial Kähler potential. To examine these landscapes we introduce a random matrix model that describes the correlations between various derivatives and we propose an efficient algorithm that allows for a numerical study of high dimensional random fields. Using these novel tools, we find that the vast majority of metastable critical points in N dimensional random supergravities are either approximately supersymmetric with |F|≪Msusy or supersymmetric. Such approximately supersymmetric points are dynamical attractors in the landscape and the probability that a randomly chosen critical point is metastable scales as log (P)∝−N. We argue that random supergravities lead to potentially interesting inflationary dynamics

  8. RANDOM LASSO.

    Science.gov (United States)

    Wang, Sijian; Nan, Bin; Rosset, Saharon; Zhu, Ji

    2011-03-01

    We propose a computationally intensive method, the random lasso method, for variable selection in linear models. The method consists of two major steps. In step 1, the lasso method is applied to many bootstrap samples, each using a set of randomly selected covariates. A measure of importance is yielded from this step for each covariate. In step 2, a similar procedure to the first step is implemented with the exception that for each bootstrap sample, a subset of covariates is randomly selected with unequal selection probabilities determined by the covariates' importance. Adaptive lasso may be used in the second step with weights determined by the importance measures. The final set of covariates and their coefficients are determined by averaging bootstrap results obtained from step 2. The proposed method alleviates some of the limitations of lasso, elastic-net and related methods noted especially in the context of microarray data analysis: it tends to remove highly correlated variables altogether or select them all, and maintains maximal flexibility in estimating their coefficients, particularly with different signs; the number of selected variables is no longer limited by the sample size; and the resulting prediction accuracy is competitive or superior compared to the alternatives. We illustrate the proposed method by extensive simulation studies. The proposed method is also applied to a Glioblastoma microarray data analysis. PMID:22997542

  9. Bimodal gastroretentive drug delivery systems of lamotrigine: Formulation and evaluation

    Directory of Open Access Journals (Sweden)

    R R Poonuru

    2014-01-01

    Full Text Available Gastroretentive bimodal drug delivery systems of lamotrigine were developed using immediate release and extended release segments incorporated in a hydroxypropyl methylcellulose capsule and in vitro and in vivo evaluations were conducted. In vivo radiographic studies were carried out for the optimized formulation in healthy human volunteers with replacement of drug polymer complex by barium sulphate and the floating time was noted. Here the immediate release segment worked as loading dose and extended release segment as maintenance dose. The results of release studies of formulations with hydrophillic matrix to formulations with dual matrix hydroxypropyl methylcellulose acetate succinate shown that as the percentage of polymer increased, the release decreased. Selected formulation F2 having F-Melt has successfully released the drug within one hour and hydrophillic matrix composing polyethylene oxide with 5% hydroxypropyl methylcellulose acetate succinate showed a lag time of one hour and then extended its release up to 12th hour with 99.59% drug release following zero order kinetics with R 2 value of 0.989. The Korsmeyer-Peppas equation showed the R 2 value to be 0.941 and n value was 1.606 following non-Fickian diffusion pattern with supercase II relaxation mechanism. Here from extended release tablet the drug released slowly from the matrix while floating.

  10. The bimodal initial mass function in the Orion Nebula Cloud

    CERN Document Server

    Drass, H; Chini, R; Bayo, A; Hackstein, M; Hoffmeister, V; Godoy, N; Vogt, N

    2016-01-01

    Due to its youth, proximity and richness the Orion Nebula Cloud (ONC) is an ideal testbed to obtain a comprehensive view on the Initial Mass Function (IMF) down to the planetary mass regime. Using the HAWK-I camera at the VLT, we have obtained an unprecedented deep and wide near-infrared JHK mosaic of the ONC (90% completeness at K~19.0mag, 22'x28). Applying the most recent isochrones and accounting for the contamination of background stars and galaxies, we find that ONC's IMF is bimodal with distinct peaks at about 0.25 and 0.025 M_sun separated by a pronounced dip at the hydrogen burning limit (0.08 M_sun), with a depth of about a factor 2-3 below the log-normal distribution. Apart from ~920 low-mass stars (M 0.005 M_sun, hence about ten times more substellar candidates than known before. The substellar IMF peak at 0.025 M_sun could be caused by BDs and IPMOs which have been ejected from multiple systems during the early star-formation process or from circumstellar disks.

  11. On the bimodal distribution of gamma-ray bursts

    Science.gov (United States)

    Mao, Shude; Narayan, Ramesh; Piran, Tsvi

    1994-01-01

    Kouveliotou et al. recently confirmed that gamma-ray bursts are bimodal in duration. In this paper we compute the statistical properties of the short (less than or = 2 s) and long (greater than 2 s) bursts using a method of analysis that makes no assumption regarding the location of the bursts, whether in the Galaxy or at a cosmological distance. We find the 64 ms channel on Burst and Transient Source Experiment (BATSE) to be more sensitive to short bursts and the 1024 ms channel to be more sensitive to long bursts. We show that all the currently available data are consistent with the simple hypothesis that both short and long bursts have the same spatial distribution and that within each population the sources are standard candles. The rate of short bursts per unit volume is about 40% of the rate of long bursts. Although the durations of short and long gamma-ray bursts span several orders of magnitude and the total energy of a typical short burst is smaller than that of a typical long burst by a factor of about 20, surprisingly the peak luminosities of the two kinds of bursts are equal to within a factor of about 2.

  12. The ventriloquist effect results from near-optimal bimodal integration.

    Science.gov (United States)

    Alais, David; Burr, David

    2004-02-01

    Ventriloquism is the ancient art of making one's voice appear to come from elsewhere, an art exploited by the Greek and Roman oracles, and possibly earlier. We regularly experience the effect when watching television and movies, where the voices seem to emanate from the actors' lips rather than from the actual sound source. Originally, ventriloquism was explained by performers projecting sound to their puppets by special techniques, but more recently it is assumed that ventriloquism results from vision "capturing" sound. In this study we investigate spatial localization of audio-visual stimuli. When visual localization is good, vision does indeed dominate and capture sound. However, for severely blurred visual stimuli (that are poorly localized), the reverse holds: sound captures vision. For less blurred stimuli, neither sense dominates and perception follows the mean position. Precision of bimodal localization is usually better than either the visual or the auditory unimodal presentation. All the results are well explained not by one sense capturing the other, but by a simple model of optimal combination of visual and auditory information. PMID:14761661

  13. Mesoporous europo-gadolinosilicate nanoparticles as bimodal medical imaging agents and a potential theranostic platform.

    Science.gov (United States)

    Tse, Nicholas M K; Kennedy, Danielle F; Kirby, Nigel; Moffat, Bradford A; Muir, Benjamin W; Caruso, Rachel A; Drummond, Calum J

    2013-06-01

    The mesoporous structure of sol-gel prepared gadolinium and europium doped silicate nanoparticles has been found to be highly dependent on the formulated composition, with synthesised samples displaying both disordered and hexagonally ordered mesoporous packing symmetry. The degree of pore ordering within the nanoparticles has a strong correlation with the total lanthanide (Gd(3+) and Eu(3+) ) concentration. The gadolinosilicates are excellent magnetic resonance imaging (MRI) longitudinal (T1 ) agents. The longitudinal relaxivity (r1 ) and transverse (r2 ) relaxivity, a measure of MRI contrast agent efficiency, were up to four times higher than the clinically employed Omniscan (gadodiamide); with r1 up to 20.6 s(-1) mM(-1) and r2 of 66.2 s(-1) mM(-1) compared to 5.53 and 4.64 s(-1) mM(-1) , respectively, for Omniscan. In addition, the europium content of all the samples studied is below the self-quenching limit, which results in a strong luminescence response from the nanoparticles on excitation at 250 nm. The Eu-Gd silicate nanoparticles act as bimodal imaging agents for MRI and luminescence. These mesoporous nanoparticles also have the potential to serve as encapsulation and controlled release matrices for pharmaceuticals. They are therefore a promising multimodal theranostic platform. PMID:23296572

  14. On the nature of bimodal initial velocity distribution of neutron stars

    OpenAIRE

    I. BombaciUniversità di Pisa, Dipartimento di Fisica;; Popov, S.B.

    2015-01-01

    We propose that the bimodal nature of the kick velocity distribution of radio pulsars is connected with the dichotomy between hadronic stars ({\\it i.e.} neutron stars with no quark matter content) and quark stars. Bimodality can appear due to different mechanisms of explosion which leads to the formation of two types of compact stars or due to two different sets of parameters mastering a particular kick mechanism. The low velocity maximum (at $\\sim 100$ km s$^{-1}$) is connected with hadronic...

  15. Interferometer and sensor based on bimodal optical waveguides, and detection method

    OpenAIRE

    Domínguez, Carlos; Zinoviev, Kirill; Laura M. Lechuga

    2007-01-01

    [EN]: Planar optical waveguide interferometer (15, 25, 35, 45) comprising: a substrate (8, 28, 38, 48); a bimodal waveguide (10, 20, 20', 30, 40) comprising at least one layer (1, 2, 3) deposited on said substrate (8, 28, 38, 48), said bimodal waveguide (10, 20, 20', 30, 40) being designed for supporting a zeroorder and a first-order transverse propagating modes, said transverse propagating modes having different dispersion; a sensor plate (21, 31, 41, 51) located in a se...

  16. Integration of Visual and Infrared Information in Bimodal Neurons of the Rattlesnake Optic Tectum

    OpenAIRE

    Newman, Eric A.; Hartline, Peter H.

    1981-01-01

    Bimodal neurons in the rattlesnake tectum, which receive sensory input from the retina and from the infrared-sensing pit organ, exhibit novel, highly nonlinear cross-modality interactions. Some units respond only to simultaneous bimodal stimulation. Others respond to only one of the two modalities, but show greatly enhanced or depressed responses when stimulated simultaneously in the second modality. These cross-modality interactions may play an important role in recognizing and orienting tow...

  17. Multiple regimes of operation in bimodal AFM: understanding the energy of cantilever eigenmodes

    OpenAIRE

    Daniel Kiracofe; Arvind Raman; Dalia Yablon

    2013-01-01

    One of the key goals in atomic force microscopy (AFM) imaging is to enhance material property contrast with high resolution. Bimodal AFM, where two eigenmodes are simultaneously excited, confers significant advantages over conventional single-frequency tapping mode AFM due to its ability to provide contrast between regions with different material properties under gentle imaging conditions. Bimodal AFM traditionally uses the first two eigenmodes of the AFM cantilever. In this work, the authors...

  18. A geometric construction of Coxeter-Dynkin diagrams of bimodal singularities

    OpenAIRE

    Ebeling, Wolfgang; Ploog, David

    2011-01-01

    We consider the Berglund-H\\"ubsch transpose of a bimodal invertible polynomial and construct a triangulated category associated to the compactification of a suitable deformation of the singularity. This is done in such a way that the corresponding Grothendieck group with the (negative) Euler form can be described by a graph which corresponds to the Coxeter-Dynkin diagram with respect to a distinguished basis of vanishing cycles of the bimodal singularity.

  19. Speech Recognition Performance in Children with Cochlear Implants Using Bimodal Stimulation

    OpenAIRE

    Rathna Kumar, S. B.; Mohanty, P.; Prakash, S. G. R.

    2010-01-01

    Cochlear implantees have considerably good speech understanding abilities in quiet surroundings. But, ambient noise poses significant difficulties in understanding speech for these individuals. Bimodal stimulation is still not used by many Indian implantees in spite of reports that bimodal stimulation is beneficial for speech understanding in noise as compared to cochlear implant alone and also prevents auditory deprivation in the un-implanted ear. The aim of the study is to evaluate the bene...

  20. The relative phonetic contributions of a cochlear implant and residual acoustic hearing to bimodal speech perceptiona

    OpenAIRE

    Sheffield, Benjamin M.; Zeng, Fan-Gang

    2012-01-01

    The addition of low-passed (LP) speech or even a tone following the fundamental frequency (F0) of speech has been shown to benefit speech recognition for cochlear implant (CI) users with residual acoustic hearing. The mechanisms underlying this benefit are still unclear. In this study, eight bimodal subjects (CI users with acoustic hearing in the non-implanted ear) and eight simulated bimodal subjects (using vocoded and LP speech) were tested on vowel and consonant recognition to determine th...

  1. Binaural advantages in users of bimodal and bilateral cochlear implant devices

    OpenAIRE

    Kokkinakis, Kostas; Pak, Natalie

    2013-01-01

    This paper investigates to what extent users of bilateral and bimodal fittings should expect to benefit from all three different binaural advantages found to be present in normal-hearing listeners. Head-shadow and binaural squelch are advantages occurring under spatially separated speech and noise, while summation emerges when speech and noise coincide in space. For 14 bilateral or bimodal listeners, speech reception thresholds in the presence of four-talker babble were measured in sound-fiel...

  2. Not Just for Bimodal Neurons Anymore: The Contribution of Unimodal Neurons to Cortical Multisensory Processing

    OpenAIRE

    Allman, Brian L.; Keniston, Leslie P.; Meredith, M. Alex

    2009-01-01

    Traditionally, neuronal studies of multisensory processing proceeded by first identifying neurons that were overtly multisensory (e.g., bimodal, trimodal) and then testing them. In contrast, the present study examined, without precondition, neurons in an extrastriate visual area of the cat for their responses to separate (visual, auditory) and combined-modality (visual and auditory) stimulation. As expected, traditional bimodal forms of multisensory neurons were identified. In addition, howev...

  3. Plasticity and Damage in Bimodal Grain Size Al-5083: Microstructural Finite Element

    OpenAIRE

    Nelson, Steven

    2010-01-01

    Bimodal and nanocrystalline aluminum alloys are being investigated as stronger replacements for conventional polycrystalline aluminum alloys. Higher strengths are achieved by reducing the grain size of a metal; however, as the grain size is reduced the ductility diminishes. One solution that limits this decrease in ductility is the addition of a few microcrystalline grains into a nanocrystalline alloy, creating a bimodal microstructure that offers a better balance of strength and ductility....

  4. Dynamics of fully coupled rotators with unimodal and bimodal frequency distribution

    OpenAIRE

    Olmi, Simona; Torcini, Alessandro

    2015-01-01

    We analyze the synchronization transition of a globally coupled network of N phase oscillators with inertia (rotators) whose natural frequencies are unimodally or bimodally distributed. In the unimodal case, the system exhibits a discontinuous hysteretic transition from an incoherent to a partially synchronized (PS) state. For sufficiently large inertia, the system reveals the coexistence of a PS state and of a standing wave (SW) solution. In the bimodal case, the hysteretic synchronization t...

  5. The SLUGGS Survey: NGC 3115, A Critical Test Case for Metallicity Bimodality in Globular Cluster Systems

    CERN Document Server

    Brodie, Jean P; Conroy, Charlie; Strader, Jay; Arnold, Jacob A; Forbes, Duncan A; Romanowsky, Aaron J

    2012-01-01

    Due to its proximity (9 Mpc) and the strongly bimodal color distribution of its spectroscopically well-sampled globular cluster (GC) system, the early-type galaxy NGC 3115 provides one of the best available tests of whether the color bimodality widely observed in GC systems generally reflects a true metallicity bimodality. Color bimodality has alternatively been attributed to a strongly nonlinear color--metallicity relation reflecting the influence of hot horizontal branch stars. Here we couple Subaru Suprime-Cam gi photometry with Keck/DEIMOS spectroscopy to accurately measure GC colors and a CaT index that measures the CaII triplet. We find the NGC 3115 GC system to be unambiguously bimodal in both color and the CaT index. Using simple stellar population models, we show that the CaT index is essentially unaffected by variations in horizontal branch morphology over the range of metallicities relevant to GC systems (and is thus a robust indicator of metallicity) and confirm bimodality in the metallicity distr...

  6. THE SLUGGS SURVEY: NGC 3115, A CRITICAL TEST CASE FOR METALLICITY BIMODALITY IN GLOBULAR CLUSTER SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Brodie, Jean P.; Conroy, Charlie; Arnold, Jacob A.; Romanowsky, Aaron J. [University of California Observatories and Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Usher, Christopher; Forbes, Duncan A. [Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122 (Australia); Strader, Jay, E-mail: brodie@ucolick.org [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

    2012-11-10

    Due to its proximity (9 Mpc) and the strongly bimodal color distribution of its spectroscopically well-sampled globular cluster (GC) system, the early-type galaxy NGC 3115 provides one of the best available tests of whether the color bimodality widely observed in GC systems generally reflects a true metallicity bimodality. Color bimodality has alternatively been attributed to a strongly nonlinear color-metallicity relation reflecting the influence of hot horizontal-branch stars. Here, we couple Subaru Suprime-Cam gi photometry with Keck/DEIMOS spectroscopy to accurately measure GC colors and a CaT index that measures the Ca II triplet. We find the NGC 3115 GC system to be unambiguously bimodal in both color and the CaT index. Using simple stellar population models, we show that the CaT index is essentially unaffected by variations in horizontal-branch morphology over the range of metallicities relevant to GC systems (and is thus a robust indicator of metallicity) and confirm bimodality in the metallicity distribution. We assess the existing evidence for and against multiple metallicity subpopulations in early- and late-type galaxies and conclude that metallicity bi/multimodality is common. We briefly discuss how this fundamental characteristic links directly to the star formation and assembly histories of galaxies.

  7. Randomization tests

    CERN Document Server

    Edgington, Eugene

    2007-01-01

    Statistical Tests That Do Not Require Random Sampling Randomization Tests Numerical Examples Randomization Tests and Nonrandom Samples The Prevalence of Nonrandom Samples in Experiments The Irrelevance of Random Samples for the Typical Experiment Generalizing from Nonrandom Samples Intelligibility Respect for the Validity of Randomization Tests Versatility Practicality Precursors of Randomization Tests Other Applications of Permutation Tests Questions and Exercises Notes References Randomized Experiments Unique Benefits of Experiments Experimentation without Mani

  8. Meaningful Effect Sizes, Intra-Class Correlations, and Proportions of Variance Explained by Covariates for Planning 3 Level Cluster Randomized Experiments in Prevention Science

    Science.gov (United States)

    Dong, Nianbo; Reinke, Wendy M.; Herman, Keith C.; Bradshaw, Catherine P.; Murray, Desiree W.

    2015-01-01

    Cluster randomized experiments are now widely used to examine intervention effects in prevention science. It is meaningful to use empirical benchmarks for interpreting effect size in prevention science. The effect size (i.e., the standardized mean difference, calculated by the difference of the means between the treatment and control groups,…

  9. Neural Correlates of Feigned Memory Impairment are Distinguishable from Answering Randomly and Answering Incorrectly: An fMRI and Behavioral Study

    Science.gov (United States)

    Liang, Chun-Yu; Xu, Zhi-Yuan; Mei, Wei; Wang, Li-Li; Xue, Li; Lu, De Jian; Zhao, Hu

    2012-01-01

    Previous functional magnetic resonance imaging (fMRI) studies have identified activation in the prefrontal-parietal-sub-cortical circuit during feigned memory impairment when comparing with truthful telling. Here, we used fMRI to determine whether neural activity can differentiate between answering correctly, answering randomly, answering…

  10. Bimodal tholeiitic-dacitic magmatism and the Early Precambrian crust

    Science.gov (United States)

    Barker, F.; Peterman, Z.E.

    1974-01-01

    Interlayered plagioclase-quartz gneisses and amphibolites from 2.7 to more than 3.6 b.y. old form much of the basement underlying Precambrian greenstone belts of the world; they are especially well-developed and preserved in the Transvaal and Rhodesian cratons. We postulate that these basement rocks are largely a metamorphosed, volcanic, bimodal suite of tholeiite and high-silica low-potash dacite-compositionally similar to the 1.8-b.y.-old Twilight Gneiss - and partly intrusive equivalents injected into the lower parts of such volcanic piles. We speculate that magmatism in the Early Precambrian involved higher heat flow and more hydrous conditions than in the Phanerozoic. Specifically, we suggest that the early degassing of the Earth produced a basaltic crust and pyrolitic upper mantle that contained much amphibole, serpentine, and other hydrous minerals. Dehydration of the lower parts of a downgoing slab of such hydrous crust and upper mantle would release sufficient water to prohibit formation of andesitic liquid in the upper part of the slab. Instead, a dacitic liquid and a residuum of amphibole and other silica-poor phases would form, according to Green and Ringwood's experimental results. Higher temperatures farther down the slab would cause total melting of basalt and generation of the tholeiitic member of the suite. This type of magma generation and volcanism persisted until the early hydrous lithosphere was consumed. An implication of this hypothesis is that about half the present volume of the oceans formed before about 2.6 b.y. ago. ?? 1974.

  11. Bimodal Size Distribution of Gold Nanoparticles under Picosecond Laser Pulses.

    Science.gov (United States)

    Inasawa, Susumu; Sugiyama, Masakazu; Yamaguchi, Yukio

    2005-05-19

    The evolution of size distributions of gold nanoparticles under pulsed laser irradiation (Nd:YAG, lambda = 355 nm, pulse width 30 ps) was carefully observed by transmission electron microscopy. Interestingly, the initial monomodal size distribution of gold nanoparticles turned into a bimodal one, with two peaks in the number of particles, one at 6 nm and the other at 16-24 nm. The sizes for small particles depended very little on the irradiated laser energy. This change is attributed to laser-induced size reduction of the initial gold nanoparticles followed by the formation of small particles. In our analysis, we extracted a characteristic value for the size-reduction rate per one pulse and revealed that laser-induced size reduction of gold nanoparticles occurred even below the boiling point. When laser energy is insufficient for the boiling of particles, formation of gold vapor around liquid gold drops is thought to cause the phenomenon. With enough laser energy for the boiling, the formation of gold vapor around and inside liquid gold drops is responsible for the phenomenon. We also observed particles with gold strings after one pulse irradiation with a laser energy of 43 mJ cm(-2) pulse(-1), which is sufficient energy for the boiling. It is considered that such particles with gold strings are formed by the projection of gaseous gold from liquid gold drops with some volume of liquid gold around the bubble. On the basis of comparison with previous work, picosecond laser pulses are thought to be the most efficient way to cause laser-induced size reduction of gold nanoparticles. PMID:16852127

  12. Asymmetric polarity reversals, bimodal field distribution, and coherence resonance in a spherically symmetric mean-field dynamo model

    CERN Document Server

    Stefani, F; Stefani, Frank; Gerbeth, Gunter

    2004-01-01

    Using a mean-field dynamo model with a spherically symmetric helical turbulence parameter alpha which is dynamically quenched and disturbed by additional noise, the basic features of geomagnetic polarity reversals are shown to be generic consequences of the dynamo action in the vicinity of exceptional points of the spectrum. This simple paradigmatic model yields long periods of constant polarity which are interrupted by self-accelerating field decays leading to asymmetric polarity reversals. It shows the recently discovered bimodal field distribution, and it gives a natural explanation of the correlation between polarity persistence time and field strength. In addition, we find typical features of coherence resonance in the dependence of the persistence time on the noise.

  13. Expression of EGFR and HPV-associated p16 in oropharyngeal carcinoma: Correlation and influence on prognosis after radiotherapy in the randomized DAHANCA 5 and 7 trials

    DEFF Research Database (Denmark)

    Lassen, Pernille; Overgaard, Jens; Eriksen, Jesper Grau

    2013-01-01

    EGFR and HPV-associated p16 are among the most investigated biomarkers in head and neck cancer. The aim was to investigate the correlation and interaction between these two markers and to evaluate their potential prognostic significance when combined.......EGFR and HPV-associated p16 are among the most investigated biomarkers in head and neck cancer. The aim was to investigate the correlation and interaction between these two markers and to evaluate their potential prognostic significance when combined....

  14. Family Intervention for Co-occurring Substance Use and Severe Psychiatric Disorders: Participant Characteristics and Correlates of Initial Engagement and More Extended Exposure in a Randomized Controlled Trial

    OpenAIRE

    MUESER, KIM T; Glynn, Shirley M.; Cather, Corrine; Zarate, Roberto; Fox, Lindy; Feldman, James; Wolfe, Rosemarie; Clark, Robin E.

    2009-01-01

    Clients with severe mental illness and substance use disorder (i.e., dual disorders) frequently have contact with family members, who may provide valuable emotional and material support, but have limited skills and knowledge to promote recovery. Furthermore, high levels of family conflict and stress are related to higher rates of relapse. The present study was a two-site randomized controlled trial comparing a comprehensive, behaviorally-based family intervention for dual disorders program (F...

  15. The bimodal pH distribution of volcanic lake waters

    Science.gov (United States)

    Marini, Luigi; Vetuschi Zuccolini, Marino; Saldi, Giuseppe

    2003-02-01

    Volcanic lake waters have a bimodal pH distribution with an acidic mode at pH 0.5-1.5 and a near neutral mode at pH 6-6.5, with relatively few samples having pH 3.5-5. To investigate the reasons for this distribution, the irreversible water-rock mass exchanges during the neutralization of acid SO 4-Cl waters with andesite, under both low- and high-temperature conditions, were simulated by means of the EQ3/6 software package, version 7.2. Reaction path modeling under low temperature and atmospheric P CO 2 and f O 2, suggests that several homogeneous and/or heterogeneous pH buffers exist both in the acidic and neutral regions, but no buffer is active in the intermediate, central pH region. Again, the same titration, under high-temperature, hydrothermal-magmatic conditions, is expected to produce comparatively infrequent aqueous solutions with pH values in the 3.5-5 range, upon their cooling below 100°C. Substantially different pH values are obtained depending on the cooling paths, either through boiling or conductive heat losses. These distinct pH values are governed by either HSO 4- and HCl (aq), in poorly neutralized aqueous solutions, or the CO 2(aq)/HCO 3- couple and the P CO 2 value as well, in neutralized aqueous solutions. Finally, mixing of the acid lake water with the aqueous solutions produced through high-temperature titration and cooled below 100°C is unlikely to generate mixtures with pH values higher than 3, unless the fraction of the acidic water originally present in the lake becomes very small, which means its virtually complete substitution. Summing up, the evidence gathered through reaction path modeling of the neutralization of acid lake waters with andesite, both at low and high temperatures, explains the scarcity of volcanic lake waters with measured pH values of 3.5-5.

  16. Lateral Erosion Encourages Vertical Incision in a Bimodal Alluvial River

    Science.gov (United States)

    Gran, K. B.

    2015-12-01

    Sand can have a strong impact on gravel transport, increasing gravel transport rates by orders of magnitude as sand content increases. Recent experimental work by others indicates that adding sand to an armored bed can even cause armor to break-up and mobilize. These two elements together help explain observations from a bimodal sand and gravel-bedded river, where lateral migration into sand-rich alluvium breaks up the armor layer, encouraging further incision into the bed. Detailed bedload measurements were coupled with surface and subsurface grain size analyses and cross-sectional surveys in a seasonally-incised channel carved into the upper alluvial fan of the Pasig-Potrero River at Mount Pinatubo, Philippines. Pinatubo erupted in 1991, filling valleys draining the flanks of the volcano with primarily sand-sized pyroclastic flow debris. Twenty years after the eruption, sand-rich sediment inputs are strongly seasonal, with most sediment input to the channel during the rainy season. During the dry season, flow condenses from a wide braided planform to a single-thread channel in most of the upper basin, extending several km onto the alluvial fan. This change in planform creates similar unit discharge ranges in summer and winter. Lower sediment loads in the dry season drive vertical incision until the bed is sufficiently armored. Incision proceeds downstream in a wave, with increasing sediment transport rates and decreasing grain size with distance downstream, eventually reaching a gravel-sand transition and return to a braided planform. Incision depths in the gravel-bedded section exceeded 3 meters in parts of a 4 km-long study reach, a depth too great to be explained by predictions from simple winnowing during incision. Instead, lateral migration into sand-rich alluvium provides sufficient fine sediment to break up the armor surface, allowing incision to start anew and increasing the total depth of the seasonally-incised valley. Lateral migration is recorded in a

  17. Integrated propulsion and power modeling for bimodal nuclear thermal rockets

    Science.gov (United States)

    Clough, Joshua

    Bimodal nuclear thermal rocket (BNTR) engines have been shown to reduce the weight of space vehicles to the Moon, Mars, and beyond by utilizing a common reactor for propulsion and power generation. These savings lead to reduced launch vehicle costs and/or increased mission safety and capability. Experimental work of the Rover/NERVA program demonstrated the feasibility of NTR systems for trajectories to Mars. Numerous recent studies have demonstrated the economic and performance benefits of BNTR operation. Relatively little, however, is known about the reactor-level operation of a BNTR engine. The objective of this dissertation is to develop a numerical BNTR engine model in order to study the feasibility and component-level impact of utilizing a NERVA-derived reactor as a heat source for both propulsion and power. The primary contribution is to provide the first-of-its-kind model and analysis of a NERVA-derived BNTR engine. Numerical component models have been modified and created for the NERVA reactor fuel elements and tie tubes, including 1-D coolant thermodynamics and radial thermal conduction with heat generation. A BNTR engine system model has been created in order to design and analyze an engine employing an expander-cycle nuclear rocket and Brayton cycle power generator using the same reactor. Design point results show that a 316 MWt reactor produces a thrust and specific impulse of 66.6 kN and 917 s, respectively. The same reactor can be run at 73.8 kWt to produce the necessary 16.7 kW electric power with a Brayton cycle generator. This demonstrates the feasibility of BNTR operation with a NERVA-derived reactor but also indicates that the reactor control system must be able to operate with precision across a wide power range, and that the transient analysis of reactor decay heat merits future investigation. Results also identify a significant reactor pressure-drop limitation during propulsion and power-generation operation that is caused by poor tie tube

  18. Contributions of electric and acoustic hearing to bimodal speech and music perception.

    Science.gov (United States)

    Crew, Joseph D; Galvin, John J; Landsberger, David M; Fu, Qian-Jie

    2015-01-01

    Cochlear implant (CI) users have difficulty understanding speech in noisy listening conditions and perceiving music. Aided residual acoustic hearing in the contralateral ear can mitigate these limitations. The present study examined contributions of electric and acoustic hearing to speech understanding in noise and melodic pitch perception. Data was collected with the CI only, the hearing aid (HA) only, and both devices together (CI+HA). Speech reception thresholds (SRTs) were adaptively measured for simple sentences in speech babble. Melodic contour identification (MCI) was measured with and without a masker instrument; the fundamental frequency of the masker was varied to be overlapping or non-overlapping with the target contour. Results showed that the CI contributes primarily to bimodal speech perception and that the HA contributes primarily to bimodal melodic pitch perception. In general, CI+HA performance was slightly improved relative to the better ear alone (CI-only) for SRTs but not for MCI, with some subjects experiencing a decrease in bimodal MCI performance relative to the better ear alone (HA-only). Individual performance was highly variable, and the contribution of either device to bimodal perception was both subject- and task-dependent. The results suggest that individualized mapping of CIs and HAs may further improve bimodal speech and music perception. PMID:25790349

  19. Contributions of electric and acoustic hearing to bimodal speech and music perception.

    Directory of Open Access Journals (Sweden)

    Joseph D Crew

    Full Text Available Cochlear implant (CI users have difficulty understanding speech in noisy listening conditions and perceiving music. Aided residual acoustic hearing in the contralateral ear can mitigate these limitations. The present study examined contributions of electric and acoustic hearing to speech understanding in noise and melodic pitch perception. Data was collected with the CI only, the hearing aid (HA only, and both devices together (CI+HA. Speech reception thresholds (SRTs were adaptively measured for simple sentences in speech babble. Melodic contour identification (MCI was measured with and without a masker instrument; the fundamental frequency of the masker was varied to be overlapping or non-overlapping with the target contour. Results showed that the CI contributes primarily to bimodal speech perception and that the HA contributes primarily to bimodal melodic pitch perception. In general, CI+HA performance was slightly improved relative to the better ear alone (CI-only for SRTs but not for MCI, with some subjects experiencing a decrease in bimodal MCI performance relative to the better ear alone (HA-only. Individual performance was highly variable, and the contribution of either device to bimodal perception was both subject- and task-dependent. The results suggest that individualized mapping of CIs and HAs may further improve bimodal speech and music perception.

  20. Bulge-disc decompositions and structural bimodality of Ursa Major cluster spiral galaxies

    Science.gov (United States)

    McDonald, Michael; Courteau, Stéphane; Tully, R. Brent

    2009-02-01

    We present bulge and disc (B/D) decompositions of existing K' surface brightness profiles for 65 Ursa Major (UMa) cluster spiral galaxies. This improves upon the disc-only fits of Tully et al. The 1996 disc fits were used by Tully & Verheijen for their discovery of the bimodality of structural parameters in the UMa cluster galaxies. It is shown that our new one-dimensional B/D decompositions yield disc structural parameters that differ only slightly from the basic fits of Tully et al. and evidence for structural bimodality of UMa galaxies is maintained. Our B/D software for the decomposition of one-dimensional surface brightness profiles of galaxies uses a non-linear minimization scheme to recover the best-fitting Sérsic bulge and the exponential disc while accounting for the possible presence of a compact nucleus and spiral arms and for the effects of seeing and disc truncations. In agreement with Tully & Verheijen, we find that the distribution of near-infrared disc central surface brightnesses is bimodal with an F-test confidence of 80 per cent. There is also strong evidence for a local minimum in the luminosity function at . A connection between the brightness bimodality and a dynamical bimodality, based on new HI linewidths, is identified. The B/D parameters are presented in Table 1.

  1. The effects of bilateral electric and bimodal electric--acoustic stimulation on language development.

    Science.gov (United States)

    Nittrouer, Susan; Chapman, Christopher

    2009-09-01

    There is no doubt that cochlear implants have improved the spoken language abilities of children with hearing loss, but delays persist. Consequently, it is imperative that new treatment options be explored. This study evaluated one aspect of treatment that might be modified, that having to do with bilateral implants and bimodal stimulation. A total of 58 children with at least one implant were tested at 42 months of age on four language measures spanning a continuum from basic to generative in nature. When children were grouped by the kind of stimulation they had at 42 months (one implant, bilateral implants, or bimodal stimulation), no differences across groups were observed. This was true even when groups were constrained to only children who had at least 12 months to acclimatize to their stimulation configuration. However, when children were grouped according to whether or not they had spent any time with bimodal stimulation (either consistently since their first implant or as an interlude to receiving a second) advantages were found for children who had some bimodal experience, but those advantages were restricted to language abilities that are generative in nature. Thus, previously reported benefits of simultaneous bilateral implantation early in a child's life may not extend to generative language. In fact, children may benefit from a period of bimodal stimulation early in childhood because low-frequency speech signals provide prosody and serve as an aid in learning how to perceptually organize the signal that is received through a cochlear implant. PMID:19713210

  2. Spectral formation in accreting X-ray pulsars: bimodal variation of the cyclotron energy with luminosity

    Science.gov (United States)

    Becker, P. A.; Klochkov, D.; Schönherr, G.; Nishimura, O.; Ferrigno, C.; Caballero, I.; Kretschmar, P.; Wolff, M. T.; Wilms, J.; Staubert, R.

    2012-08-01

    Context. Accretion-powered X-ray pulsars exhibit significant variability of the cyclotron resonance scattering feature (CRSF) centroid energy on pulse-to-pulse timescales, and also on much longer timescales. Two types of spectral variability are observed. For sources in group 1, the CRSF energy is negatively correlated with the variable source luminosity, and for sources in group 2, the opposite behavior is observed. The physical basis for this bimodal behavior is currently not well understood. Aims: We explore the hypothesis that the accretion dynamics in the group 1 sources is dominated by radiation pressure near the stellar surface, and that Coulomb interactions decelerate the gas to rest in the group 2 sources. Methods: We derive a new expression for the critical luminosity, Lcrit, such that radiation pressure decelerates the matter to rest in sources with X-ray luminosity LX > Lcrit. The formula for Lcrit is based on a simple physical model for the structure of the accretion column in luminous X-ray pulsars that takes into account radiative deceleration, the energy dependence of the cyclotron cross section, the thermodynamics of the accreting gas, the dipole structure of the pulsar magnetosphere, and the diffusive escape of radiation through the column walls. We show that for typical neutron star parameters, Lcrit = 1.5 × 1037 B1216/15 erg s-1, where B12 is the surface magnetic field strength in units of 1012 G. Results: The formula for the critical luminosity is evaluated for five sources, using the maximum value of the CRSF centroid energy to estimate the surface magnetic field strength B12. The results confirm that the group 1 sources are supercritical (LX > Lcrit) and the group 2 sources are subcritical (LX function of LX for both the group 1 (supercritical) and the group 2 (subcritical) sources as a result of the variation of the emission height in the column.

  3. Formulation And Evaluation Of Bilayer Tablet for Bimodal Release of Venlafaxine Hydrochloride

    Directory of Open Access Journals (Sweden)

    Munira eMomin

    2015-07-01

    Full Text Available The aim of the present research was to develop a bilayer tablet of venlafexine hydrochloride for bimodal drug release. In the present investigation authors have tried to explore Fenugreek Mucilage (FNM for bioadhesive sustained release layer. The attempt has been made to combine FNM with well studied bioahesive polymers like Hydroxy Propyl Methyl Cellulose, Carbopol and Xanthan Gum. The formulations were evaluated for swelling Index, ex-vivo bioadhesion, water uptake studies, in-vitro drug release and dissolution kinetics was studied. Substantial bioadhesion force (2.4±0.023 gms and tablet adhesion retention time (24±2 hrs was observed with FNM and HPMC combination at 80:20 ratio. The dissolution kinetics followed the Higuchi model (R2 =0.9913 via a non-Fickian diffusion controlled release mechanism after the initial burst. The 32 full factorial design was employed in the present study. The type of polymers used in combination with FNM (X1 and percent polymer replaced with FNM (X2 were taken as independent formulations variables. The selected responses, bioadhesion force (0.11-0.25±0.023gm, amount of drug released in 10 h, Y10 (78.20–95.78±1.24 % and bioadhesive strength, (19-24±2hrs presented good correlation with the selected independent variables. Statistical analysis (ANOVA of the optimized bilayer formulations showed no significant difference in the cumulative amount of drug release after 15 min, but significant difference (p < 0.05 in the amount of drug released after 1 hr till 12 h from optimized formulations was observed. The natural mucilage like FNM could be successfully incorporated into tablet with only 20% replacement with HPMC and it showed good bioadhesiveness and sustained drug release.

  4. Occurrence of Tertiary bimodal volcanism in the Mucuri Basin; Ocorrencia de vulcanismo bimodal de idade terciaria na Bacia de Mucuri

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Newton Souza; Suita, Marcos Tadeu de Freitas [Universidade Federal de Ouro Preto (UFOP). Escola de Minas. Dept. de Geologia (Brazil)], e-mails: newton@degeo.ufop.br, suita@degeo.ufop.br

    2010-05-15

    Since the last century two distinct ages of magmatic activity have been recognized in the Espirito Santo and Mucuri basins. The first, interpreted as Cretaceous, is related to the South Atlantic opening and is registered by its tholeiitic basalts of the Barremian aged Cabiunas Formation. The second and most expressive volcanic activity in the basin was formed during Tertiary times and generated basalts described as of an alkaline nature, from the Abrolhos Formation. Recent studies of core samples obtained from two wells made by PETROBRAS in the offshore part of the Mucuri Basin identified volcanic rocks of intermediate to acid nature on the top of the Abrolhos Formation. The presence of rhyolites and trachytes on the top of basalts characterized for the first time a bimodal volcanism in the submersed part of this basin. In both these lithologies, the substitution of the matrix minerals by carbonate and zeolites, is probably due to the interaction of the rocks with seawater. The two sampled wells are something like 120km apart, which suggests that due to small lateral continuity, characteristic of acid to intermediate magmas, these so distant occurrences should reflect proximity with their volcanic conduits. The presence of volcanic rock fragments immediately overlaying the calcarenites, base of the Caravelas Formation, documented in the core samples, supports the registration of the extrusion of intermediate to acid lithotypes in the final stages of the Abrolhos volcanism. Furthermore, other occurrences of rhyolitic and ignimbrite rocks are reported over the Sao Mateus crystalline basement regions, Espirito Santo State and in the northeastern part of Minas Gerais State. Also they appear as intercalated levels in the sandstones of the Rio Doce Formation in the most southern part of Bahia State and could have a cogenetic character and be related to the ending of the Abrolhos Tertiary magmatism the dimension of which has been underestimated until the present

  5. Nucleation of cracks near the free surface in deformed metallic nanomaterials with a bimodal structure

    Science.gov (United States)

    Ovid'ko, I. A.; Sheinerman, A. G.

    2016-06-01

    A theoretical model that effectively describes the nucleation of cracks in stress fields of dislocation pile-ups near the free surface in metallic nanomaterials with a bimodal structure has been developed. The dependences of the critical shear stress τ c (for the formation of a crack with an equilibrium length of 10 nm on a dislocation pile-up near the surface) on the size d of a grain containing the dislocation pile-up have been calculated for copper with a bimodal structure. Theoretically, it has been found that the critical shear stress τ c for the nucleation of a crack near the free surface in a nanomaterial with a bimodal structure is approximately 30% higher than that for the crack nucleation within the nanomaterial at a distance from the free surface.

  6. Exact results for the Kuramoto model with a bimodal frequency distribution

    DEFF Research Database (Denmark)

    Martens, Erik Andreas; Barreto, E.; Strogatz, S. H.;

    2009-01-01

    We analyze a large system of globally coupled phase oscillators whose natural frequencies are bimodally distributed. The dynamics of this system has been the subject of long-standing interest. In 1984 Kuramoto proposed several conjectures about its behavior; ten years later, Crawford obtained the...... first analytical results by means of a local center manifold calculation. Nevertheless, many questions have remained open, especially about the possibility of global bifurcations. Here we derive the system’s stability diagram for the special case where the bimodal distribution consists of two equally...... bifurcation boundaries between these states. Similar results are also obtained for the case in which the bimodal distribution is given by the sum of two Gaussians....

  7. Bimodal distribution of glucose is not universally useful for diagnosing diabetes

    DEFF Research Database (Denmark)

    Vistisen, Dorte; Colagiuri, Stephen; Borch-Johnsen, Knut;

    2009-01-01

    excluding known diabetes. RESEARCH DESIGN AND METHODS: The Evaluation of Screening and Early Detection Strategies for Type 2 Diabetes and Impaired Glucose Tolerance (DETECT-2) project is an international collaboration pooling surveys from all continents. These studies include surveys in which plasma glucose......OBJECTIVE: Bimodality in the distribution of glucose has been used to define the cut point for the diagnosis of diabetes. Previous studies on bimodality have primarily been in populations with a high prevalence of type 2 diabetes, including one study in a white Caucasian population. All studies...... included participants with known diabetes. The aim of this study was to assess whether a bimodal structure is a general phenomenon in fasting plasma glucose (FPG) and 2-h plasma glucose that is useful for deriving a common cut point for diabetes in populations of different origin, both including and...

  8. Random Walks on Random Graphs

    Science.gov (United States)

    Cooper, Colin; Frieze, Alan

    The aim of this article is to discuss some of the notions and applications of random walks on finite graphs, especially as they apply to random graphs. In this section we give some basic definitions, in Section 2 we review applications of random walks in computer science, and in Section 3 we focus on walks in random graphs.

  9. Random duality

    Institute of Scientific and Technical Information of China (English)

    GUO TieXin; CHEN XinXiang

    2009-01-01

    The purpose of this paper is to provide a random duality theory for the further development of the theory of random conjugate spaces for random normed modules.First,the complicated stratification structure of a module over the algebra L(μ,K) frequently makes our investigations into random duality theory considerably different from the corresponding ones into classical duality theory,thus in this paper we have to first begin in overcoming several substantial obstacles to the study of stratification structure on random locally convex modules.Then,we give the representation theorem of weakly continuous canonical module homomorphisms,the theorem of existence of random Mackey structure,and the random bipolar theorem with respect to a regular random duality pair together with some important random compatible invariants.

  10. Random duality

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The purpose of this paper is to provide a random duality theory for the further development of the theory of random conjugate spaces for random normed modules. First, the complicated stratification structure of a module over the algebra L(μ, K) frequently makes our investigations into random duality theory considerably difierent from the corresponding ones into classical duality theory, thus in this paper we have to first begin in overcoming several substantial obstacles to the study of stratification structure on random locally convex modules. Then, we give the representation theorem of weakly continuous canonical module homomorphisms, the theorem of existence of random Mackey structure, and the random bipolar theorem with respect to a regular random duality pair together with some important random compatible invariants.

  11. Currículum Bimodal : reduirem el fracàs escolar?

    OpenAIRE

    Marquès, Pere

    2012-01-01

    Una investigació desenvolupada al Departament de Pedagogia Aplicada de la UAB ha estudiat l'aplicació del currículum bimodal, que separa els coneixements que s'han de memoritzar de les competències que s'han d'adquirir, en diversos centres d'ensenyament a Espanya i a Amèrica Llatina. Els resultats mostren una millora en el rendiment dels alumnes, alhora que també un increment en la seva motivació davant de les classes. Així, el currículum bimodal obre una porta a l'esperança en la millora de ...

  12. Evidence of bimodal crystallite size distribution in μc-Si:H films

    International Nuclear Information System (INIS)

    We report on the microstructural characterization studies carried out on plasma deposited highly crystalline undoped microcrystalline silicon films to explore the crystallite size distribution present in this material. The modeling of results of spectroscopic ellipsometry using two different sized crystallites is corroborated by the deconvolution of experimental Raman profiles using a modeling method that incorporates a bimodal size distribution of crystallites. The presence of a bimodal size distribution of crystallites is demonstrated as well by the results of atomic force microscopy and X-ray diffraction studies. The qualitative agreement between the results of different studies is discussed.

  13. Particle-size distribution and packing fraction of geometric random packings

    NARCIS (Netherlands)

    Brouwers, H.J.H.

    2006-01-01

    This paper addresses the geometric random packing and void fraction of polydisperse particles. It is demonstrated that the bimodal packing can be transformed into a continuous particle-size distribution of the power law type. It follows that a maximum packing fraction of particles is obtained when t

  14. Bidding Strategies for Generation Company Considering Randomness and Correlation Relationship of Electricity and Carbon Prices%考虑电价碳价随机性及其相关性的发电商投标决策

    Institute of Scientific and Technical Information of China (English)

    周任军; 刘照; 陈彦秀; 张浩; 李莹莹; 范龙; 尹权

    2016-01-01

    Carbon price and electricity price are bound together under the influence of external factors. Thus,the price randomness of carbon and electricity along with their correlation should be taken into consideration to form the bidding model for generation compa-nies. The difference between actual profit and the expectation is defined as the risk and measured by multi-stochastic conditional risk method in this paper. Then,a CVaR-based bidding model which considers the price randomness of electricity and carbon along with their correlation is proposed. The Linear method is used to sample of the random variables concerning the correlation and to solve the conditional value at risk. Cases considering the correlation between electricity price and carbon price,carbon price cost,carbon price randomness and other risk measurement methods are tested respectively to evaluate their influences on the investment decision risk of generation companies. The results show that considering the price randomness of both electricity and carbon as well as their correlation is more in accordance with the generation companies’requirement of increasing revenue and reducing risk,and conditional risk method is able to describe the risk more accurately.%电价、碳价在外界因素的影响下具有某种相依关系,因此需要在发电商投标模型中考虑电价、碳价的随机性及其相关性对其决策的影响。本文将低于发电商预期收益部分的期望值定义为风险,采用多随机变量的条件风险方法对其进行度量,建立了考虑电价碳价随机性及其相关性影响的发电商投标决策模型,利用线性变换方法对相关性随机变量进行抽样并求解条件风险值。对电价碳价相关性、碳价成本、碳价随机性和不同风险度量方法对发电商投资决策风险的影响进行了仿真对比,结果表明考虑电价和碳价随机性及其相关性影响的投标模型更符合发电商提高收益降低

  15. 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

  16. Energy randomness

    OpenAIRE

    Miller, Joseph S.; Rute, Jason

    2015-01-01

    Energy randomness is a notion of partial randomness introduced by Diamondstone and Kjos-Hanssen to characterize the sequences that can be elements of a Martin-L\\"of random closed set (in the sense of Barmpalias, Brodhead, Cenzer, Dashti, and Weber). It has also been applied by Allen, Bienvenu, and Slaman to the characterization of the possible zero times of a Martin-L\\"of random Brownian motion. In this paper, we show that $X \\in 2^\\omega$ is $s$-energy random if and only if $\\sum_{n\\in\\omega...

  17. Parallel Bimodal Bilingual Acquisition: A Hearing Child Mediated in a Deaf Family

    Science.gov (United States)

    Cramér-Wolrath, Emelie

    2013-01-01

    The aim of this longitudinal case study was to describe bimodal and bilingual acquisition in a hearing child, Hugo, especially the role his Deaf family played in his linguistic education. Video observations of the family interactions were conducted from the time Hugo was 10 months of age until he was 40 months old. The family language was Swedish…

  18. The Taylor-expansion method of moments for the particle system with bimodal distribution

    Directory of Open Access Journals (Sweden)

    Liu Yan-Hua

    2013-01-01

    Full Text Available This paper derives the multipoint Taylor expansion method of moments for the bimodal particle system. The collision effects are modeled by the internal and external coagulation terms. Simple theory and numerical tests are performed to prove the effect of the current model.

  19. ON THE PROPORTIONALITY OF FINE MASS CONCENTRATION AND EXTINCTION COEFFICIENT FOR BIMODAL SIZE DISTRIBUTIONS

    Science.gov (United States)

    For a bimodal size distribution of ambient aerosol, an upper limit in particle size can be chosen for the fine aerosol fraction so that the extinction coefficient for light scattering and absorption is directly proportional to the fine mass concentration, with no dependence on th...

  20. Influence of attention on bimodal integration during emotional change decoding: ERP evidence.

    Science.gov (United States)

    Chen, Xuhai; Han, Lingzi; Pan, Zhihui; Luo, Yangmei; Wang, Ping

    2016-08-01

    Recent findings on audiovisual emotional interactions suggest that selective attention affects cross-sensory interaction from an early processing stage. However, the influence of attention manipulation on facial-vocal integration during emotional change perception is still elusive at this point. To address this issue, we asked participants to detect emotional changes conveyed by prosodies (vocal task) or facial expressions (facial task) while facial, vocal, and facial-vocal expressions were presented. At the same time, behavioral responses and electroencephalogram (EEG) were recorded. Behavioral results showed that bimodal emotional changes were detected with shorter response latencies compared to each unimodal condition, suggesting that bimodal emotional cues facilitated emotional change detection. Moreover, while the P3 amplitudes were larger for the bimodal change condition than for the sum of the two unimodal conditions regardless of attention direction, the N1 amplitudes were larger for the bimodal emotional change condition than for the sum of the two unimodal conditions under the attend-voice condition, but not under the attend-face condition. These findings suggest that selective attention modulates facial-vocal integration during emotional change perception in early sensory processing, but not in late cognitive processing stages. PMID:27238075

  1. Gaze-independent ERP-BCIs: augmenting performance through location-congruent bimodal stimuli.

    NARCIS (Netherlands)

    Thurlings, Marieke; Brouwer, Anne-Marie; Erp, van, Jan B.F.; Werkhoven, Peter

    2014-01-01

    Gaze-independent event-related potential (ERP) based brain-computer interfaces (BCIs) yield relatively low BCI performance and traditionally employ unimodal stimuli. Bimodal ERP-BCIs may increase BCI performance due to multisensory integration or summation in the brain. An additional advantage of bi

  2. Deaf Parents of Cochlear-Implanted Children: Beliefs on Bimodal Bilingualism

    Science.gov (United States)

    Mitchiner, Julie Cantrell

    2015-01-01

    This study investigated 17 Deaf families in North America with cochlear-implanted children about their attitudes, beliefs, and practices on bimodal bilingualism (defined as using both a visual/manual language and an aural/oral language) in American Sign Language (ASL) and English. A survey and follow-up interviews with 8 families were conducted.…

  3. Bimodal Emotion Congruency Is Critical to Preverbal Infants' Abstract Rule Learning

    Science.gov (United States)

    Tsui, Angeline Sin Mei; Ma, Yuen Ki; Ho, Anna; Chow, Hiu Mei; Tseng, Chia-huei

    2016-01-01

    Extracting general rules from specific examples is important, as we must face the same challenge displayed in various formats. Previous studies have found that bimodal presentation of grammar-like rules (e.g. ABA) enhanced 5-month-olds' capacity to acquire a rule that infants failed to learn when the rule was presented with visual presentation of…

  4. Effects of Removing Low-Frequency Electric Information on Speech Perception with Bimodal Hearing

    Science.gov (United States)

    Fowler, Jennifer R.; Eggleston, Jessica L.; Reavis, Kelly M.; McMillan, Garnett P.; Reiss, Lina A. J.

    2016-01-01

    Purpose: The objective was to determine whether speech perception could be improved for bimodal listeners (those using a cochlear implant [CI] in one ear and hearing aid in the contralateral ear) by removing low-frequency information provided by the CI, thereby reducing acoustic-electric overlap. Method: Subjects were adult CI subjects with at…

  5. Perception of Consonants in Reverberation and Noise by Adults Fitted with Bimodal Devices

    Science.gov (United States)

    Mason, Michelle; Kokkinakis, Kostas

    2014-01-01

    Purpose: The purpose of this study was to evaluate the contribution of a contralateral hearing aid to the perception of consonants, in terms of voicing, manner, and place-of-articulation cues in reverberation and noise by adult cochlear implantees aided by bimodal fittings. Method: Eight postlingually deafened adult cochlear implant (CI) listeners…

  6. Cross-Frequency Integration for Consonant and Vowel Identification in Bimodal Hearing

    Science.gov (United States)

    Kong, Ying-Yee; Braida, Louis D.

    2011-01-01

    Purpose: Improved speech recognition in binaurally combined acoustic-electric stimulation (otherwise known as "bimodal hearing") could arise when listeners integrate speech cues from the acoustic and electric hearing. The aims of this study were (a) to identify speech cues extracted in electric hearing and residual acoustic hearing in the…

  7. Gaze-independent ERP-BCIs : Augmenting performance through location-congruent bimodal stimuli

    NARCIS (Netherlands)

    Thurlings, M.E.; Brouwer, A.M.; Erp, J.B.F. van; Werkhoven, P.J.

    2014-01-01

    Gaze-independent event-related potential (ERP) based brain-computer interfaces (BCIs) yield relatively low BCI performance and traditionally employ unimodal stimuli. Bimodal ERP-BCIs may increase BCI performance due to multisensory integration or summation in the brain. An additional advantage of bi

  8. Song Recognition by Young Children with Cochlear Implants: Comparison between Unilateral, Bilateral, and Bimodal Users

    Science.gov (United States)

    Bartov, Tamar; Most, Tova

    2014-01-01

    Purpose: To examine song identification by preschoolers with normal hearing (NH) versus preschoolers with cochlear implants (CIs). Method: Participants included 45 children ages 3;8-7;3 (years;months): 12 with NH and 33 with CIs, including 10 with unilateral CI, 14 with bilateral CIs, and 9 bimodal users (CI-HA) with unilateral CI and…

  9. Fano resonance in two-dimensional optical waveguide arrays with a bi-modal defect

    OpenAIRE

    Vicencio, R.; Gorbach, A.; Flach, S.

    2005-01-01

    We study the two-dimensional extension of the Fano-Anderson model on the basis of a two-dimensional optical waveguide array with a bi-modal defect. We demonstrate numerically the persistence of the Fano resonance in wavepacket scattering process by the defect. An analytical approximation is derived for the total scattered light power.

  10. Solving System Of Linear Equations Using The Bimodal Optical Computer (Experimental Results)

    Science.gov (United States)

    Habli, M. A.; Abushagur, M. A. G.; Caulfield, H. J.

    1988-08-01

    Hardware and software design of the Bimodal Optical Computer (BOC) and its implementations are presented. Experimental results of the BOC for solving a system of linear equations Ax = b is reported. The effect of calibration, the convergence reliability of the BOC, and the convergence of problems with singular matrices are studied.

  11. "Bimodal" Nuclear Thermal Rocket (BNTR) Propulsion for Future Human Mars Exploration Missions

    Science.gov (United States)

    Borowski, Stanley K.

    2004-01-01

    The Nuclear Thermal Rocket (NTR) Propulsion program is discussed. The Rover/NERVA program from 1959-1972 is compared with the current program. A key technology description, bimodal vehicle design for Mars Cargo and the crew transfer vehicle with inflatable module and artificial gravity capability, including diagrams are included. The LOX-Augmented NTR concept/operational features and characteristics are discussed.

  12. Matching Automatic Gain Control Across Devices in Bimodal Cochlear Implant Users

    NARCIS (Netherlands)

    Veugen, L.C.E.; Chalupper, J.; Snik, A.F.M; Opstal, A.J. van; Mens, L.H.M

    2016-01-01

    OBJECTIVES: The purpose of this study was to improve bimodal benefit in listeners using a cochlear implant (CI) and a hearing aid (HA) in contralateral ears, by matching the time constants and the number of compression channels of the automatic gain control (AGC) of the HA to the CI. Equivalent AGC

  13. The Bi-Modal Organization: Balancing Autopoiesis and Fluid Social Networks for Sustainability

    Science.gov (United States)

    Smith, Peter A. C.; Sharicz, Carol Ann

    2013-01-01

    Purpose: The purpose of this paper is to assist an organization to restructure as a bi-modal organization in order to achieve sustainability in today's highly complex business world. Design/methodology/approach: The paper is conceptual and is based on relevant literature and the authors' research and practice. Findings: Although fluid…

  14. An examination of bimodal nuclear power and propulsion benefits for outer solar system missions

    Energy Technology Data Exchange (ETDEWEB)

    Zubrin, R. [Lockheed Martin Atronautics, PO Box 179, Denver, Colorado 80201 (United States); Mondt, J. [Jet Propulsion Lab, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)

    1996-03-01

    This paper presents the results of an analysis of the capability of nuclear bimodal systems to perform outer solar system exploration missions. Missions of interest include orbiter missions to Jupiter, Saturn, Uranus, Neptune, and Pluto. An initial technology baseline consisting of the NEBA 10 kWe, 1000 N thrust, 850 s, 1500 kg bimodal system was selected, and its performance examined against a data base for trajectories to outer solar system planetary destinations to select optimal direct and gravity assisted trajectories for study. A conceptual design for a common bimodal spacecraft capable of performing missions to all the planetary destinations was developed and made the basis of end to end mission designs for orbiter missions to Jupiter, Saturn, and Neptune. All mission designs considered use the Atlas 2AS for launch. The radiological hazard associated with using Earth gravity assists on such missions was examined and shown to be small compared to that currently accepted on Earth fly-by missions involving RTGs. It is shown that the bimodal nuclear power and propulsion system offers many attractive options for planetary missions, including both conventional planetary missions in which all instruments are carried by a single primary orbiting spacecraft, and unconventional missions in which the primary spacecraft acts as a carrier, relay, and mother ship for a fleet of micro spacecraft deployed at the planetary destination. {copyright} {ital 1996 American Institute of Physics.}

  15. The Centaurus cluster of galaxies. II. The bimodal-velocity structure

    International Nuclear Information System (INIS)

    This is the second paper in a series that describes an extensive study of the Centaurus cluster of galaxies. The paper concerns the bimodal velocity distribution of the galaxies in the cluster. The likely location of the two main cluster components is discussed. The data strongly favours the hypothesis that the two components lie within the same cluster. (UK)

  16. Randomized random walk on a random walk

    International Nuclear Information System (INIS)

    This paper discusses generalizations of the model introduced by Kehr and Kunter of the random walk of a particle on a one-dimensional chain which in turn has been constructed by a random walk procedure. The superimposed random walk is randomised in time according to the occurrences of a stochastic point process. The probability of finding the particle in a particular position at a certain instant is obtained explicitly in the transform domain. It is found that the asymptotic behaviour for large time of the mean-square displacement of the particle depends critically on the assumed structure of the basic random walk, giving a diffusion-like term for an asymmetric walk or a square root law if the walk is symmetric. Many results are obtained in closed form for the Poisson process case, and these agree with those given previously by Kehr and Kunter. (author)

  17. Estimation of geological structure around underground tunnel based on cross-correlation analyses of random continuous signals from small scale core drilling

    International Nuclear Information System (INIS)

    We have studied a reflection imaging technique in which passive seismic signals from other construction activity such as drilling noise are used as a source signal in order to develop a low-cost measurement method inside underground gallery. In this paper, we show an application to data sets from the Mizunami Underground Research Laboratory of Japan Atomic Energy Agency. The drilling was conducted with a main purpose of extraction rock core samples for rock mechanics research. The three-dimensional reflection imaging results and comparison with borehole observation are shown in this paper. Firstly, we show a concept and advantages of utilization of drilling noise inside narrow underground gallery, and explain analytical technique based on correlation analysis of three-component waveforms by which we can theoretically obtain three-dimensional imaging results even with only one single point observation. Next, we describe an outline of the data acquisition at Mizunami, and characteristics of observed drilling noise waveforms. Then, we show results of reflection imaging by using drilling noise signals, and compare those with fractures based on borehole observations. We discuss relationship between the estimated three-dimensional reflection images and possible spatial distribution of fractures. These results infer that the proposed technique can be useful tool when we need additional geological information in order to achieve maximum safety at reasonable low-cost in case at a narrow space such as for a high level radioactive waste repository development. (author)

  18. Bimodal emotion congruency is critical to preverbal infants' abstract rule learning.

    Science.gov (United States)

    Tsui, Angeline Sin Mei; Ma, Yuen Ki; Ho, Anna; Chow, Hiu Mei; Tseng, Chia-huei

    2016-05-01

    Extracting general rules from specific examples is important, as we must face the same challenge displayed in various formats. Previous studies have found that bimodal presentation of grammar-like rules (e.g. ABA) enhanced 5-month-olds' capacity to acquire a rule that infants failed to learn when the rule was presented with visual presentation of the shapes alone (circle-triangle-circle) or auditory presentation of the syllables (la-ba-la) alone. However, the mechanisms and constraints for this bimodal learning facilitation are still unknown. In this study, we used audio-visual relation congruency between bimodal stimulation to disentangle possible facilitation sources. We exposed 8- to 10-month-old infants to an AAB sequence consisting of visual faces with affective expressions and/or auditory voices conveying emotions. Our results showed that infants were able to distinguish the learned AAB rule from other novel rules under bimodal stimulation when the affects in audio and visual stimuli were congruently paired (Experiments 1A and 2A). Infants failed to acquire the same rule when audio-visual stimuli were incongruently matched (Experiment 2B) and when only the visual (Experiment 1B) or the audio (Experiment 1C) stimuli were presented. Our results highlight that bimodal facilitation in infant rule learning is not only dependent on better statistical probability and redundant sensory information, but also the relational congruency of audio-visual information. A video abstract of this article can be viewed at https://m.youtube.com/watch?v=KYTyjH1k9RQ. PMID:26280911

  19. Spectral statistics of random geometric graphs

    CERN Document Server

    Dettmann, Carl P; Knight, Georgie

    2016-01-01

    We study the spectrum of random geometric graphs using random matrix theory. We look at short range correlations in the level spacings via the nearest neighbour and next nearest neighbour spacing distribution and long range correlations via the spectral rigidity $\\Delta_3$ statistic. These correlations in the level spacings give information about localisation of eigenvectors, level of community structure and the level of randomness within the networks. We find that the spectral statistics of random geometric graphs fits the universality of random matrix theory. In particular, the short range correlations are very close to those found in the Gaussian orthogonal ensemble of random matrix theory. For long range correlations we find deviations from Gaussian orthogonal ensemble statistics towards Poisson. We compare with previous results for Erd\\H{o}s-R\\'{e}nyi, Barab{\\'a}si-Albert and Watts-Strogatz random graphs where similar random matrix theory universality has been found.

  20. Random field distributed Heisenberg model on a thin film geometry

    International Nuclear Information System (INIS)

    The effects of the bimodal random field distribution on the thermal and magnetic properties of the Heisenberg thin film have been investigated by making use of a two spin cluster with the decoupling approximation. Particular attention has been devoted to the obtaining of phase diagrams and magnetization behaviors. The physical behaviors of special as well as tricritical points are discussed for a wide range of selected Hamiltonian parameters. For example, it is found that when the strength of a magnetic field increases, the locations of the special point (which is the ratio of the surface exchange interaction and the exchange interaction of the inner layers that makes the critical temperature of the film independent of the thickness) in the related plane decrease. Moreover, tricritical behavior has been obtained for higher values of the magnetic field, and influences of the varying Hamiltonian parameters on its behavior have been elucidated in detail in order to have a better understanding of the mechanism underlying the considered system. - Highlights: • Effect of bimodal random field distribution within the Heisenberg model is investigated. • Phase diagrams of the random field Heisenberg model in a thin film geometry are obtained. • Effect of the random field on the magnetic properties is obtained. • Variation of the special point with random field is determined. • Variation of the tricritical point with random field is determined

  1. Bimodal Respiratory-Locomotor Neurons in the Neonatal Rat Spinal Cord.

    Science.gov (United States)

    Le Gal, Jean-Patrick; Juvin, Laurent; Cardoit, Laura; Morin, Didier

    2016-01-20

    Neural networks that can generate rhythmic motor output in the absence of sensory feedback, commonly called central pattern generators (CPGs), are involved in many vital functions such as locomotion or respiration. In certain circumstances, these neural networks must interact to produce coordinated motor behavior adapted to environmental constraints and to satisfy the basic needs of an organism. In this context, we recently reported the existence of an ascending excitatory influence from lumbar locomotor CPG circuitry to the medullary respiratory networks that is able to depolarize neurons of the parafacial respiratory group during fictive locomotion and to subsequently induce an increased respiratory rhythmicity (Le Gal et al., 2014b). Here, using an isolated in vitro brainstem-spinal cord preparation from neonatal rat in which the respiratory and the locomotor networks remain intact, we show that during fictive locomotion induced either pharmacologically or by sacrocaudal afferent stimulation, the activity of both thoracolumbar expiratory motoneurons and interneurons is rhythmically modulated with the locomotor activity. Completely absent in spinal inspiratory cells, this rhythmic pattern is highly correlated with the hindlimb ipsilateral flexor activities. Furthermore, silencing brainstem neural circuits by pharmacological manipulation revealed that this locomotor-related drive to expiratory motoneurons is solely dependent on propriospinal pathways. Together these data provide the first evidence in the newborn rat spinal cord for the existence of bimodal respiratory-locomotor motoneurons and interneurons onto which both central efferent expiratory and locomotor drives converge, presumably facilitating the coordination between the rhythmogenic networks responsible for two different motor functions. Significance statement: In freely moving animals, distant regions of the brain and spinal cord controlling distinct motor acts must interact to produce the best

  2. A bimodal catalytic membrane having a hydrogen-permselective silica layer on a bimodal catalytic support: Preparation and application to the steam reforming of methane

    OpenAIRE

    Tsuru, Toshinori; Shintani, Hiroaki; Yoshioka, Tomohisa; Asaeda, Masashi

    2006-01-01

    The steam reforming of methane for hydrogen production was experimentally investigated using catalytic membrane reactors, consisting of a microporous silica top layer, for the selective permeation of hydrogen, and an α-alumina support layer, for catalytic reaction of the steam reforming of methane. An α-alumina support layer with a bimodal structure, which was proposed for the enhanced dispersion of Ni catalysts, was prepared by impregnating γ-Al2O3 inside α-Al2O3 microfiltration membranes (1...

  3. Reconstructing random media

    International Nuclear Information System (INIS)

    We formulate a procedure to reconstruct the structure of general random heterogeneous media from limited morphological information by extending the methodology of Rintoul and Torquato [J. Colloid Interface Sci. 186, 467 (1997)] developed for dispersions. The procedure has the advantages that it is simple to implement and generally applicable to multidimensional, multiphase, and anisotropic structures. Furthermore, an extremely useful feature is that it can incorporate any type and number of correlation functions in order to provide as much morphological information as is necessary for accurate reconstruction. We consider a variety of one- and two-dimensional reconstructions, including periodic and random arrays of rods, various distribution of disks, Debye random media, and a Fontainebleau sandstone sample. We also use our algorithm to construct heterogeneous media from specified hypothetical correlation functions, including an exponentially damped, oscillating function as well as physically unrealizable ones. copyright 1998 The American Physical Society

  4. Drawing a random number

    DEFF Research Database (Denmark)

    Wanscher, Jørgen Bundgaard; Sørensen, Majken Vildrik

    2006-01-01

    Random numbers are used for a great variety of applications in almost any field of computer and economic sciences today. Examples ranges from stock market forecasting in economics, through stochastic traffic modelling in operations research to photon and ray tracing in graphics. The construction of...... a model or a solution method requires certain characteristics of the random numbers used. This is usually a distribution classification, which the sequence of random numbers must fulfill; of these some are very hard to fulfill and others are next to impossible. Today mathematics allows us to...... is to generate highly uniform multidimensional draws, which are highly relevant for todays traffic models. This paper shows among others combined shuffling and scrambling seems needless, that scrambling gives the lowest correlation and that there are detectable differences between random numbers...

  5. Bimodal Distribution of Sulfuric Acid Aerosols in the Upper Haze of Venus

    CERN Document Server

    Gao, Peter; Crisp, David; Bardeen, Charles G; Yung, Yuk L

    2013-01-01

    The upper haze (UH) of Venus is variable on the order of days and it is populated by two particle modes. We use a 1D microphysics and vertical transport model based on the Community Aerosol and Radiation Model for Atmospheres to evaluate whether interaction of upwelled cloud particles and sulfuric acid particles nucleated in situ on meteoric dust are able to generate the two size modes and whether their observed variability are due to cloud top vertical transient winds. Nucleation of photochemically produced sulfuric acid onto polysulfur condensation nuclei generates mode 1 cloud droplets that then diffuse upwards into the UH. Droplets generated in the UH from nucleation of sulfuric acid onto meteoric dust coagulate with the upwelled cloud particles and cannot reproduce the observed bimodal size distribution. The mass transport enabled by cloud top transient winds are able to generate a bimodal size distribution in a time scale consistent with observations. Sedimentation and convection in the middle and lower...

  6. Super stellar clusters with a bimodal hydrodynamic solution: an Approximate Analytic Approach

    CERN Document Server

    Wünsch, R; Palous, J; Tenorio-Tagle, G

    2007-01-01

    We look for a simple analytic model to distinguish between stellar clusters undergoing a bimodal hydrodynamic solution from those able to drive only a stationary wind. Clusters in the bimodal regime undergo strong radiative cooling within their densest inner regions, which results in the accumulation of the matter injected by supernovae and stellar winds and eventually in the formation of further stellar generations, while their outer regions sustain a stationary wind. The analytic formulae are derived from the basic hydrodynamic equations. Our main assumption, that the density at the star cluster surface scales almost linearly with that at the stagnation radius, is based on results from semi-analytic and full numerical calculations. The analytic formulation allows for the determination of the threshold mechanical luminosity that separates clusters evolving in either of the two solutions. It is possible to fix the stagnation radius by simple analytic expressions and thus to determine the fractions of the depo...

  7. Formation of bimodal porous silica-titania monoliths by sol-gel route

    International Nuclear Information System (INIS)

    Silica-titania monoliths with micrometer-scale macroporous and nanometer-scale mesoporous structure and high titania contents are prepared by sol-gel process and phase separation. Titanium alkoxide precursor was not effective in the preparation of high titania content composites because of strong decrease in phase separation tendency. Bimodal porous gels with high titania content were obtained by using inorganic salt precursors such as titanium sulfate and titanium chloride. Various characterization techniques, including SEM, XRD, Hg porosimetry and N2 adsorption have been carried out to investigate the formation process and physical-chemical properties of silica-titania monoliths. The characterization results show that the silica-titania monoliths possess a bimodal porous structure with well-dispersed titania inside silica network. The addition of titania in silica improves the thermal stability of both macroporous and mesoporous structures.

  8. Bimodality as a signal of liquid-gas phase transition in nuclei?

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, O.; Lacroix, D.; Vient, E

    2005-09-15

    We use the HIPSE (Heavy-Ion Phase-Space Exploration) Model to discuss the origin of the bi-modality in charge asymmetry observed in nuclear reactions around the Fermi energy. We show that it may be related to the important angular momentum (spin) transferred into the quasi-projectile before secondary decay. As the spin overcomes the critical value, a sudden opening of decay channels is induced and leads to a bimodal distribution for the charge asymmetry. In the model, it is not assigned to a liquid-gas phase transition but to specific instabilities in nuclei with high spin. Therefore, we propose to use these reactions to study instabilities in rotating nuclear droplets. (authors)

  9. Bimodality as a signal of the nuclear liquid-gas phase transition

    CERN Document Server

    Sagun, V V; Oliinychenko, D R; Bugaev, K A

    2014-01-01

    Here we present an explicit counterexample to a bimodality concept as the unique signal of first order phase transition. Using an exact solution of the simplified version of the statistical multifragmentation model we demonstrate that the bimodal distributions can naturally appear in infinite system without a phase transition in the regions of the negative values of the surface tension coefficient. Also we propose a new parameterization for the compressible nuclear liquid which is consistent with the L. van Hove axioms of statistical mechanics. As a result the proposed model does not lead to the irregular behaviour of the isotherms in the mixed phase region which is typical for mean-field models. Peculiarly, the suggested approach to account for the nuclear liquid compressibility automatically leads to an appearance of an additional state that in many respects resembles the physical antinuclear matter.

  10. On a Symmetric, Nonlinear Birth-Death Process with Bimodal Transition Probabilities

    OpenAIRE

    Barbara Martinucci; Antonio Di Crescenzo

    2009-01-01

    We consider a bilateral birth-death process having sigmoidal-type rates. A thorough discussion on its transient behaviour is given, which includes studying symmetry properties of the transition probabilities, finding conditions leading to their bimodality, determining mean and variance of the process, and analyzing absorption problems in the presence of 1 or 2 boundaries. In particular, thanks to the symmetry properties we obtain the avoiding transition probabilities in the presence of a pair...

  11. El Corredor Bimodal Cafetero sobre las rutas del desarrollo de Caldas

    OpenAIRE

    Duque Escobar, Gonzalo

    2015-01-01

    Corredor Bimodal transversal para la región Andina de Colombia trazado por territorio de Caldas y del Norte de Tolima, constituido por el Ferrocarril Cafetero y la Transversal Cafetera. El objeto del proyecto es integrar el Corredor Férreo del Cauca y La Hidrovía del Magdalena, y al Eje Cafetero con el Magdalena Centro. Sin ferrocarriles e hidrovías, no se puede implementar un sistema intermodal de transporte de carga en Colombia

  12. Bi-Modal Face and Speech Authentication: a BioLogin Demonstration System

    OpenAIRE

    Marcel, Sébastien; Mariéthoz, Johnny; Rodriguez, Yann; Cardinaux, Fabien

    2006-01-01

    This paper presents a bi-modal (face and speech) authentication demonstration system that simulates the login of a user using its face and its voice. This demonstration is called BioLogin. It runs both on Linux and Windows and the Windows version is freely available for download. Bio\\-Login is implemented using an open source machine learning library and its machine vision package.

  13. Generation of four-particle GHZ states in bimodal cavity QED

    Institute of Scientific and Technical Information of China (English)

    Yang Zhen-Biao

    2007-01-01

    We propose a scheme for preparing four-particle Greenberger-Horne-Zeilinger states using two identical bimodal cavities, each supports two modes with different frequencies. This scheme is an alternative to another published work[Christopher C Gerry 1996 Phys. Rev. A 53 4591]. Comparisons between them are discussed. The fidelity and the probability of success influenced by cavity decay for the generated states are also considered.

  14. Human and mouse switch-like genes share common transcriptional regulatory mechanisms for bimodality

    OpenAIRE

    Tozeren Aydin; Ertel Adam

    2008-01-01

    Abstract Background Gene expression is controlled over a wide range at the transcript level through complex interplay between DNA and regulatory proteins, resulting in profiles of gene expression that can be represented as normal, graded, and bimodal (switch-like) distributions. We have previously performed genome-scale identification and annotation of genes with switch-like expression at the transcript level in mouse, using large microarray datasets for healthy tissue, in order to study the ...

  15. Costs and advantages in bimodal bilingual language production: Language-switching and dual-task paradigms

    OpenAIRE

    Kaufmann, Emily

    2014-01-01

    Previous studies of unimodal (spoken–spoken) language switching have often found longer reaction times and higher error rates in switch trials than in repeat trials, particularly for unbalanced bilinguals. Studies of hearing signers (bimodal bilinguals) have found that they often produce ‘code-blends’ rather than sequential code-switches; such simultaneous production is generally not possible in unimodal utterances. The present study explored sequential language switching and simultaneous lan...

  16. Spin squeezing in a bimodal condensate: spatial dynamics and particle losses

    OpenAIRE

    Li, Yun; Treutlein, Philipp; Reichel, Jakob; Sinatra, Alice

    2009-01-01

    18 pages, 13 figures. Accepted for publication in European Physical Journal B International audience We propose an analytical method to study the entangled spatial and spin dynamics of interacting bimodal Bose-Einstein condensates. We show that at particular times during the evolution spatial and spin dynamics disentangle and the spin squeezing can be predicted by a simple two-mode model. We calculate the maximum spin squeezing achievable in experimentally relevant situations with Sodiu...

  17. THE BIMODAL MOLECULAR WEIGHT DISTRIBUTION OF cis-POLYBUTADIENE POLYMERIZED WITH LANTHANIDE COMPLEX CATALYSTS

    Institute of Scientific and Technical Information of China (English)

    CHENG Rongshi; HU Huizhen; JIANG Liansheng

    1987-01-01

    The variation of the molecular weight and molecular weight distribution of cis-polybutadiene in the course of polymerization catalyzed by lanthanide complex composed of triisobutyl aluminium or diisobutyl aluminium hydride was investigated by osmometry, viscometry and size exclusion chromatography. By analyzing the experimental data, the reasons of the appearance of bimodal molecular weight distribution were elucidated and the possible mechanisms of polymerization were discussed.

  18. Source analysis of bimodal event-related potentials with auditory-visual stimuli

    OpenAIRE

    Cui, H; Xie, X.; Yan, H; Feng, L; Xu, S; Hu, Y.

    2013-01-01

    Dipole source analysis is applied to model brain generators of surface-recorded evoked potentials, epileptiform activity, and event-related potentials (ERP). The aim of this study was to explore brain activity of interaction between bimodal sensory cognition. Seven healthy volunteers were recruited in the study and ERP to these stimuli were recorded by 64 electrodes EEG recording system. Subjects were exposed to either the auditory and the visual stimulus alone or the combined auditory-visual...

  19. Improved Statistical Analysis of Low Abundance Phenomena in Bimodal Bacterial Populations

    OpenAIRE

    Friedrich Reinhard; Jan Roelof van der Meer

    2013-01-01

    Accurate detection of subpopulation size determinations in bimodal populations remains problematic yet it represents a powerful way by which cellular heterogeneity under different environmental conditions can be compared. So far, most studies have relied on qualitative descriptions of population distribution patterns, on population-independent descriptors, or on arbitrary placement of thresholds distinguishing biological ON from OFF states. We found that all these methods fall short of accura...

  20. Well-posed bimodal piecewise linear systems do not exhibit Zeno behavior

    OpenAIRE

    Camlibel, Kanat

    2008-01-01

    The phenomenon of infinitely mode transitions in a finite time interval is called Zeno behavior in hybrid systems literature. It plays a critical role in the study of numerical methods and fundamental system and control theoretic properties of hybrid systems. This paper studies Zeno behavior for bimodal piecewise linear systems with possibly discontinuous dynamics. Our treatment is inspired by the work of Imura and Van der Schaft on the well-posedness of the same type of systems. The main con...

  1. Bimodal action of menthol on the transient receptor potential channel TRPA1

    OpenAIRE

    Karashima, Yuji; Damann, Nils; Prenen, Jean; Talavera Pérez, Karel; Segal Stanciu, Andrei; Voets, Thomas; Nilius, Bernd

    2007-01-01

    TRPA1 is a calcium-permeable nonselective cation transient receptor potential (TRP) channel that functions as an excitatory ionotropic receptor in nociceptive neurons. TRPA1 is robustly activated by pungent substances in mustard oil, cinnamon, and garlic and mediates the inflammatory actions of environmental irritants and proalgesic agents. Here, we demonstrate a bimodal sensitivity of TRPA1 to menthol, a widely used cooling agent and known activator of the related cold receptor TRPM8. In who...

  2. The climatic imprint of bimodal distributions in vegetation cover for western Africa

    Science.gov (United States)

    Yin, Zun; Dekker, Stefan C.; van den Hurk, Bart J. J. M.; Dijkstra, Henk A.

    2016-06-01

    Observed bimodal distributions of woody cover in western Africa provide evidence that alternative ecosystem states may exist under the same precipitation regimes. In this study, we show that bimodality can also be observed in mean annual shortwave radiation and above-ground biomass, which might closely relate to woody cover due to vegetation-climate interactions. Thus we expect that use of radiation and above-ground biomass enables us to distinguish the two modes of woody cover. However, through conditional histogram analysis, we find that the bimodality of woody cover still can exist under conditions of low mean annual shortwave radiation and low above-ground biomass. It suggests that this specific condition might play a key role in critical transitions between the two modes, while under other conditions no bimodality was found. Based on a land cover map in which anthropogenic land use was removed, six climatic indicators that represent water, energy, climate seasonality and water-radiation coupling are analysed to investigate the coexistence of these indicators with specific land cover types. From this analysis we find that the mean annual precipitation is not sufficient to predict potential land cover change. Indicators of climate seasonality are strongly related to the observed land cover type. However, these indicators cannot predict a stable forest state under the observed climatic conditions, in contrast to observed forest states. A new indicator (the normalized difference of precipitation) successfully expresses the stability of the precipitation regime and can improve the prediction accuracy of forest states. Next we evaluate land cover predictions based on different combinations of climatic indicators. Regions with high potential of land cover transitions are revealed. The results suggest that the tropical forest in the Congo basin may be unstable and shows the possibility of decreasing significantly. An increase in the area covered by savanna and grass

  3. Bi-objective bimodal urban road network design using hybrid metaheuristics

    OpenAIRE

    Miandoabchi, Elnaz; Zanjirani Farahani, Reza; Wai Yuen, Szeto

    2011-01-01

    In this paper a bimodal discrete urban road network design problem with bus and car modes is investigated. The problem consists of decision making for lane addition to the existing streets, new street constructions, converting some two-way streets to one-way streets, lane allocation for two-way streets, and the allocation of some street lanes for exclusive bus lanes. Two objectives are considered in the problem: maximization of consumer surplus, and maximization of the demand share of the bus...

  4. Multiphase flow modeling of a crude-oil spill site with a bimodal permeability distribution

    Science.gov (United States)

    Dillard, L.A.; Essaid, H.I.; Herkelrath, W.N.

    1997-01-01

    Fluid saturation, particle-size distribution, and porosity measurements were obtained from 269 core samples collected from six boreholes along a 90-m transect at a subregion of a crude-oil spill site, the north pool, near Bemidji, Minnesota. The oil saturation data, collected 11 years after the spill, showed an irregularly shaped oil body that appeared to be affected by sediment spatial variability. The particle-size distribution data were used to estimate the permeability (k) and retention curves for each sample. An additional 344 k estimates were obtained from samples previously collected at the north pool. The 613 k estimates were distributed bimodal log normally with the two population distributions corresponding to the two predominant lithologies: a coarse glacial outwash deposit and fine-grained interbedded lenses. A two-step geostatistical approach was used to generate a conditioned realization of k representing the bimodal heterogeneity. A cross-sectional multiphase flow model was used to simulate the flow of oil and water in the presence of air along the north pool transect for an 11-year period. The inclusion of a representation of the bimodal aquifer heterogeneity was crucial for reproduction of general features of the observed oil body. If the bimodal heterogeneity was characterized, hysteresis did not have to be incorporated into the model because a hysteretic effect was produced by the sediment spatial variability. By revising the relative permeability functional relation, an improved reproduction of the observed oil saturation distribution was achieved. The inclusion of water table fluctuations in the model did not significantly affect the simulated oil saturation distribution.

  5. Enhancing water flux of thin-film nanocomposite (TFN) membrane by incorporation of bimodal silica nanoparticles

    OpenAIRE

    Jun Yin; Baolin Deng; Zhe Yang

    2016-01-01

    Modern reverse osmosis (RO)/nanofiltration (NF) membranes are primarily made of thin-film composites (TFC) fabricated through interfacial polymerization of m-phenylene diamine (MPD) and trimesoyl chloride (TMC) on a polysulfone (PSF) supporting membrane. In this study, two types of bimodal silica nanoparticles (~80 nm) with different internal pore structures were synthesized and incorporated into the polyamide (PA) thin-film layer during interfacial polymerization at concentrations varying fr...

  6. Synthesis and characterization of intrinsically radiolabeled quantum dots for bimodal detection

    OpenAIRE

    Sun, Minghao; Hoffman, David; Sundaresan, Gobalakrishnan; Yang, Likun; Lamichhane, Narottam; Zweit, Jamal

    2012-01-01

    A novel approach was developed to synthesize radioactive quantum dots (r-QDs) thereby enabling both optical and radionuclide signals to be detected from the same intrinsic bimodal probe. This proof-of-concept is exemplified by the incorporation of the radionuclide 109Cadmium into the core/shell of the nanoparticle. Green and near infrared (NIR) emission intrinsic r-QDs were synthesized and characterized. Zwitterionic and Poly-polyethlene glycol (PEGylated) ligands were synthesized and used to...

  7. Theoretical study of the frequency shift in bimodal FM-AFM by fractional calculus

    OpenAIRE

    Herruzo, Elena T; Ricardo Garcia

    2012-01-01

    Bimodal atomic force microscopy is a force-microscopy method that requires the simultaneous excitation of two eigenmodes of the cantilever. This method enables the simultaneous recording of several material properties and, at the same time, it also increases the sensitivity of the microscope. Here we apply fractional calculus to express the frequency shift of the second eigenmode in terms of the fractional derivative of the interaction force. We show that this approximation is valid for situa...

  8. Bimodal character of cyclone climatology in the Bay of Bengal modulated by monsoon seasonal cycle

    Digital Repository Service at National Institute of Oceanography (India)

    Li, Z.; Yu, W.; Li, T.; Murty, V.S.N.; Fredolin, T.

    (WSP). TCs draw intense scientific and social interest concerns due to the following three reasons. Firstly, they contribute importantly to the overall summer season rainfall in regions such as WNP. Secondly they play a key role in modulating...., vol.26; 2013; 1033–1046 Bimodal character of cyclone climatology in Bay of Bengal modulated by monsoon seasonal cycle Zhi Li1, Weidong Yu1, Tim Li2, VSN Murty3 and Fredolin Tangang4 1. Center for Ocean and Climate Research, First Institute...

  9. High-strength ultrafine-grained Ti-Fe-Sn alloys with a bimodal structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, L C; Lu, H B; Pereloma, E V [Faculty of Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Calin, M; Eckert, J, E-mail: lczhangimr@gmail.co, E-mail: laichang@uow.edu.a [IFW Dresden, Institute for Complex Materials, PO Box 27 01 16, D-01171 Dresden (Germany)

    2010-07-01

    The microstructure-mechanical properties relationship in ultrafine-grained Ti-Fe-Sn alloys with high strength and large plasticity was investigated. The alloys are mainly composed of a hypereutectic microstructure with micrometer-sized primary dendrites embedded in an ultrafine-grained eutectic matrix. The bimodal composites exhibit a fracture strength higher than 2350 MPa and an enhanced plasticity larger than 7%. The excellent mechanical properties are critically related to the microstructure features of the phase constituents in the alloys.

  10. Radio-frequency triggered heating and drug release using doxorubicin-loaded LSMO nanoparticles for bimodal treatment of breast cancer.

    Science.gov (United States)

    Kulkarni, Vaishnavi M; Bodas, Dhananjay; Dhoble, Deepa; Ghormade, Vandana; Paknikar, Kishore

    2016-09-01

    Radio-frequency responsive nanomaterials combined with drugs for simultaneous hyperthermia and drug delivery are potential anti-cancer agents. In this study, chitosan coated La0.7Sr0.3MnO3 nanoparticles (C-LSMO NPs) were synthesized and characterized by X-ray diffraction, dynamic light scattering, Fourier transform infra red spectroscopy, vibrating sample magnetometer, scanning electron and atomic force microscopy. Under low radio-frequency (365kHz, RF), C-LSMO NPs (90nm) showed good colloidal stability (+22mV), superparamagnetic nature (15.4 emu/g) and heating capacity (57.4W/g SAR value). Chitosan facilitated doxorubicin entrapment (76%) resulted in DC-LSMO NPs that showed drug release upon a 5min RF exposure. MCF-7 and MDA-MB-231 cancer cells responded to a 5min RF exposure in the presence of bimodal DC-LSMO NPs with a significant decrease in viability to 73% and 88% (Pearson correlation, r=1, Pbimodal therapeutic agents for cancer treatment and hold promise against disease recurrence and drug resistance. PMID:27337564

  11. Correction: Stimuli-responsive magnetic nanoparticles for tumor-targeted bimodal imaging and photodynamic/hyperthermia combination therapy.

    Science.gov (United States)

    Kim, Kyoung Sub; Kim, Jiyoung; Lee, Joo Young; Matsuda, Shofu; Hideshima, Sho; Mori, Yasurou; Osaka, Tetsuya; Na, Kun

    2016-07-01

    Correction for 'Stimuli-responsive magnetic nanoparticles for tumor-targeted bimodal imaging and photodynamic/hyperthermia combination therapy' by Kyoung Sub Kim, et al., Nanoscale, 2016, DOI: 10.1039/c6nr02273a. PMID:27300478

  12. Correction: Stimuli-responsive magnetic nanoparticles for tumor-targeted bimodal imaging and photodynamic/hyperthermia combination therapy

    Science.gov (United States)

    Kim, Kyoung Sub; Kim, Jiyoung; Lee, Joo Young; Matsuda, Shofu; Hideshima, Sho; Mori, Yasurou; Osaka, Tetsuya; Na, Kun

    2016-06-01

    Correction for `Stimuli-responsive magnetic nanoparticles for tumor-targeted bimodal imaging and photodynamic/hyperthermia combination therapy' by Kyoung Sub Kim, et al., Nanoscale, 2016, DOI: 10.1039/c6nr02273a.

  13. International Thermonuclear Engineering Reactor: Bimodal device and design sensitivities to energy confinement H-factors

    International Nuclear Information System (INIS)

    A major concern of present-day tokamak design is the uncertainty in the plasma energy confinement scaling. We present sensitivities of designs similar to the International Thermonuclear Engineering Reactor (ITER) to changes in the energy confinement H-factor (H) for cases designed for ignition (the ITER physics phase), long-pulse, current-driven operation (the ITER technology phase), and achievement of both phases in a single device (bimodal). For cases that require ignition, the cost increases sharply for H-factors below 2. For technology-phase cases, the costs are much less sensitive to H-factor variations. For bimodal cases with H≥ 1.8, the ignition criteria dominate if the energy multiplication factor Q need only be 5 in the technology phase; if Q ≥ 10 is required, the current drive criteria dominate. The bimodal cases are at most ∼10% more expensive than the more costly of the physics-only and technology-only cases. Thus, the present ITER scheme of replacing the blanket and shield of the device between phases may not be the most cost-effective way to accomplish the desired performance goals. Investigation of device sensitivity to the H-factor indicates that, as the H-factor decreases from 1.8 to 1.2 for a given device, the achievable Q drops from ∼10 to ∼5 and the divertor heat load increases by 50%. 8 refs., 4 figs., 2 tabs

  14. Bimodal Density Distribution of Cryptodome Dacite from the 1980 Eruption of Mount St. Helens, Washington

    Science.gov (United States)

    Hoblitt, R.P.; Harmon, R.S.

    1993-01-01

    The explosion of a cryptodome at Mount St. Helens in 1980 produced two juvenile rock types that are derived from the same source magma. Their differences-color, texture and density-are due only to vesicularity differences. The vesicular gray dacite comprises bout 72% of the juvenile material; the black dacite comprises the other 28%. The density of juvenile dacite is bimodally distributed, with peaks at 1.6 g cm-3 (gray dacite) and 2.3 g cm-3 (black dacite). Water contents, deuterium abundances, and the relationship of petrographic structures to vapor-phase crystals indicate both rock types underwent pre-explosion subsurface vesiculation and degassing. The gray dacite underwent a second vesiculation event, probably during the 18 May explosion. In the subsurface, gases probably escaped through interconnected vesicles into the permeable volcanic edifice. We suggest that nonuniform degassing of an initially homogeneous magma produced volatile gradients in the cryptodome and that these gradients were responsible for the density bimodality. That is, water contents less than about 0.2-0.4 wt% produced vesicle growth rates that were slow in comparison to the pyroclast cooling rates; greater water contents produced vesicle growth rates that were fast in comparison to cooling rates. In this scheme, the dacite densities are bimodally distributed simply because, following decompression on 18 May 1980, one clast population vesiculated while the other did not. For clasts that did vesiculate, vesicle growth continued until it was arrested by fragmentation. ?? 1993 Springer-Verlag.

  15. Bimodality emerges from transport model calculations of heavy ion collisions at intermediate energy

    CERN Document Server

    Mallik, S; Chaudhuri, G

    2016-01-01

    This work is a continuation of our effort [Phys. Rev. C 91, 034616 (2015)] to examine if signatures of a phase transition can be extracted from transport model calculations of heavy ion collisions at intermediate energy. A signature of first order phase transition is the appearance of a bimodal distribution in $P_m(k)$ in finite systems. Here P_m(k) is the probability that the maximum of the multiplicity distribution occurs at mass number k. Using a well-known model for event generation (BUU plus fluctuation), we do two cases of central collision: mass 40 on mass 40 and mass 120 on mass 120. Bimodality is seen in both the cases. The results are quite similar to those obtained in statistical model calculations. An intriguing feature is seen. We observe that at the energy where bimodality occurs. other phase transition like signatures appear. There are breaks in certain first order derivatives. We then examine if such breaks appear in standard Botzmann-Uehling-Uhlenbeck (BUU) calculations without fluctuations. ...

  16. Preparation of Bimodal Mesoporous Silica Molecular Sieves from Organotrialkoxysilane and Tetraethoxysilane

    Institute of Scientific and Technical Information of China (English)

    Gong Yanjun; Mu Lin; Dou Tao

    2007-01-01

    The synthesis of silica with bimodal, disordered mesopores structure, by template-mediated sol-gel processing and subsequent heat-treatment process, was investigated. In the presence of nonionic surfactant Tx-15, the organically modified mesostructured nano-particles were synthesized by co-condensation of organosiloxane (RTES) and tetraethoxysilane (TEOS) in the first step, and then the bimodal porous silica was formed by the removal of the incorporated organic groups using programmed calcination. Here, RTES used was methyltriethoxysilane (MTES), vinyltriethoxysilane (VTES) and phenyltriethoxysilane (PhTES), respectively. Organotrialkoxysilane, TEOS and Tx-15 formed MSU-2-1iked assemblies, around which the nano-particles aggregated and cross-linked, considerably influencing the pore size distribution of both primary pores and secondary pores. By changing the type and amount of the organotrialkoxysilane added, a broad variety of silica with a controlled bimodal mesopore distribution could be easily synthesized. Textural and structural properties were determined by X-ray diffraction, high-resolution transmission electron microscopy, N2 adsorption/desorption,and thermogravimetric analysis.

  17. Bulge-Disk Decompositions and Structural Bimodality of Ursa Major Cluster Spiral Galaxies

    CERN Document Server

    McDonald, Michael; Tully, R Brent

    2008-01-01

    We present bulge and disk (B/D) decompositions of existing K'-band surface brightness profiles for 65 Ursa Major cluster spiral galaxies. This improves upon the disk-only fits of Tully et al. (1996). The 1996 disk fits were used by Tully & Verheijen (1997) for their discovery of the bimodality of structural parameters in the UMa cluster galaxies. It is shown that our new 1D B/D decompositions yield disk structural parameters that differ only slightly from the basic fits of Tully et al. and evidence for structural bimodality of UMa galaxies is maintained. Our B/D software for the decomposition of 1D surface brightness profiles of galaxies uses a non-linear minimization scheme to recover the best fitting Sersic bulge and exponential disk while accounting for the possible presence of a compact nucleus and spiral arms and for the effects of seeing and disk truncations. In agreement with Tully & Verheijen, we find that the distribution of near-infrared disk central surface brightnesses is bimodal with an F...

  18. Enhancing water flux of thin-film nanocomposite (TFN membrane by incorporation of bimodal silica nanoparticles

    Directory of Open Access Journals (Sweden)

    Jun Yin

    2016-03-01

    Full Text Available Modern reverse osmosis (RO/nanofiltration (NF membranes are primarily made of thin-film composites (TFC fabricated through interfacial polymerization of m-phenylene diamine (MPD and trimesoyl chloride (TMC on a polysulfone (PSF supporting membrane. In this study, two types of bimodal silica nanoparticles (~80 nm with different internal pore structures were synthesized and incorporated into the polyamide (PA thin-film layer during interfacial polymerization at concentrations varying from 0 to 0.1 wt%. The as-prepared membranes were characterized by scanning electron microscopy (SEM, atomic force microscopy (AFM, and attenuated total reflection Fourier transform infrared (ATR FT-IR spectroscopy, and their performances were evaluated in terms of the water permeability and salt rejection. The results showed the water permeability increased with increasing BSN concentrations, reaching a maximum of 53.5 L m−2 h−1 at a bimodal silica nanoparticle (BSN concentration of 0.5 wt% (pressure at 300 psi, NaCl concentration: 2000 ppm. This represented a flux increase of approximately 40%, while a near constant salt rejection of 95% was maintained. The study demonstrated that the internal micro-mesoporous structures of bimodal silica nanoparticles contributed significantly to the membrane performance, which is consistent with previous studies with relatively uniform internal pores.

  19. Pluto/Charon exploration utilizing a bi-modal PBR nuclear propulsion/power system

    Science.gov (United States)

    Venetoklis, Peter S.

    1995-01-01

    The paper describes a Pluto/Charon orbiter utilizing a bi-modal nuclear propulsion and power system based on the Particle Bed Reactor. The orbiter is sized for launch to Nuclear-Safe orbit atop a Titan IV or equivalent launch veicle. The bi-modal system provides thermal propulsion for Earth orbital departure and Pluto orbital capture, and 10 kWe of electric power for payload functions and for in-system maneuvering with ion thrusters. Ion thrusters are used to perform inclination changes about Pluto, a transfer from low Pluto orbit to low Charon orbit, and inclination changes about charon. A nominal payload can be deliverd in as little as 15 years, 1000 kg in 17 years, and close to 2000 kg in 20 years. Scientific return is enormously aided by the availability of up to 10 kWe, due to greater data transfer rates and more/better instruments. The bi-modal system can provide power at Pluto/Charon for 10 or more years, enabling an extremely robust, scientifically rewarding, and cost-effective exploration mission.

  20. RSMASS-D nuclear thermal propulsion and bimodal system mass models

    Energy Technology Data Exchange (ETDEWEB)

    King, D.B. [DSWA/FC, Thermionic Evaluation Facility 801 University Blvd. SE Albuquerque, New Mexico (United States); Marshall, A.C. [DSWA/FC, Thermionic Evaluation Facility 801 University Blvd. SE Albuquerque, New Mexico (United States)

    1997-01-01

    Two relatively simple models have been developed to estimate reactor, radiation shield, and balance of system masses for a particle bed reactor (PBR) nuclear thermal propulsion concept and a cermet-core power and propulsion (bimodal) concept. The approach was based on the methodology developed for the RSMASS-D models. The RSMASS-D approach for the reactor and shield sub-systems uses a combination of simple equations derived from reactor physics and other fundamental considerations along with tabulations of data from more detailed neutron and gamma transport theory computations. Relatively simple models are used to estimate the masses of other subsystem components of the nuclear propulsion and bimodal systems. Other subsystem components include instrumentation and control (I&C), boom, safety systems, radiator, thermoelectrics, heat pipes, and nozzle. The user of these models can vary basic design parameters within an allowed range to achieve a parameter choice which yields a minimum mass for the operational conditions of interest. Estimated system masses are presented for a range of reactor power levels for propulsion for the PBR propulsion concept and for both electrical power and propulsion for the cermet-core bimodal concept. The estimated reactor system masses agree with mass predictions from detailed calculations with xx percent for both models. {copyright} {ital 1997 American Institute of Physics.}

  1. RSMASS-D nuclear thermal propulsion and bimodal system mass models

    International Nuclear Information System (INIS)

    Two relatively simple models have been developed to estimate reactor, radiation shield, and balance of system masses for a particle bed reactor (PBR) nuclear thermal propulsion concept and a cermet-core power and propulsion (bimodal) concept. The approach was based on the methodology developed for the RSMASS-D models. The RSMASS-D approach for the reactor and shield sub-systems uses a combination of simple equations derived from reactor physics and other fundamental considerations along with tabulations of data from more detailed neutron and gamma transport theory computations. Relatively simple models are used to estimate the masses of other subsystem components of the nuclear propulsion and bimodal systems. Other subsystem components include instrumentation and control (I ampersand C), boom, safety systems, radiator, thermoelectrics, heat pipes, and nozzle. The user of these models can vary basic design parameters within an allowed range to achieve a parameter choice which yields a minimum mass for the operational conditions of interest. Estimated system masses are presented for a range of reactor power levels for propulsion for the PBR propulsion concept and for both electrical power and propulsion for the cermet-core bimodal concept. The estimated reactor system masses agree with mass predictions from detailed calculations with xx percent for both models. copyright 1997 American Institute of Physics

  2. Comparison between wave generation methods for numerical simulation of bimodal seas

    Directory of Open Access Journals (Sweden)

    Daniel A. Thompson

    2016-01-01

    Full Text Available This paper describes an investigation of the generation of desired sea states in a numerical wave model. Bimodal sea states containing energetic swell components can be coastal hazards along coastlines exposed to large oceanic fetches. Investigating the effects of long-period bimodal seas requires large computational domains and increased running time to ensure the development of the desired sea state. Long computational runs can cause mass stability issues due to the Stokes drift and wave reflection, which in turn affect results through the variation of the water level. A numerical wave flume, NEWRANS, was used to investigate two wave generation methods: the wave paddle method, allowing for a smaller domain; and the internal mass source function method, providing an open boundary allowing reflected waves to leave the domain. The two wave generation methods were validated against experimental data by comparing the wave generation accuracy and the variance of mass in the model during simulations. Results show that the wave paddle method not only accurately generates the desired sea state but also provides a more stable simulation, in which mass fluctuation has less of an effect on the water depth during the long-duration simulations. As a result, it is suggested that the wave paddle method with active wave absorption is preferable to the internal wave maker option when investigating intermediate-depth long-period bimodal seas for long-duration simulations.

  3. MOCCA code for star cluster simulations - VI. Bimodal spatial distribution of blue stragglers

    CERN Document Server

    Hypki, Arkadiusz

    2016-01-01

    The paper presents an analysis of formation mechanism and properties of spatial distributions of blue stragglers in evolving globular clusters, based on numerical simulations done with the MOCCA code. First, there are presented N-body and MOCCA simulations which try to reproduce the simulations presented by Ferraro (2012). Then, the agreement between N-body and the MOCCA code is shown. Finally, we discuss the formation process of the bimodal distribution. We report that so-called bimodal spatial distribution of blue stragglers is a very transient feature. It is formed for one snapshot in time and it can easily vanish in the next one. Moreover, we show that the radius of avoidance proposed by Ferraro (2012) goes out of sync with the apparent minimum of the bimodal distribution after about two half-mass relaxation times. This finding creates a real challenge for the dynamical clock, which uses this radius to determine the dynamical age of globular clusters. Additionally, the paper discusses a few important prob...

  4. A New Method of Moments for the Bimodal Particle System in the Stokes Regime

    Directory of Open Access Journals (Sweden)

    Yan-hua Liu

    2013-01-01

    Full Text Available The current paper studied the particle system in the Stokes regime with a bimodal distribution. In such a system, the particles tend to congregate around two major sizes. In order to investigate this system, the conventional method of moments (MOM should be extended to include the interaction between different particle clusters. The closure problem for MOM arises and can be solved by a multipoint Taylor-expansion technique. The exact expression is deduced to include the size effect between different particle clusters. The collision effects between different modals could also be modeled. The new model was simply tested and proved to be effective to treat the bimodal system. The results showed that, for single-modal particle system, the results from new model were the same as those from TEMOM. However, for the bimodal particle system, there was a distinct difference between the two models, especially for the zero-order moment. The current model generated fewer particles than TEMOM. The maximum deviation reached about 15% for m0 and 4% for m2. The detailed distribution of each submodal could also be investigated through current model.

  5. Physical Mechanism of Formation of the Bimodal Structure in the Meiyu Front System

    Institute of Scientific and Technical Information of China (English)

    CUI Xiao-Peng; GAO Shou-Ting; ZONG Zhi-Ping; LIU Wen-Ming; LI Xiao-Fan

    2005-01-01

    @@ The bimodal structure of the Meiyu front system is readdressed after Zhou et al.(2005). The physical mechanism of the formation of the bimodal distribution is discussed. The bimodal structure of the Meiyu front system considerably results from atmospheric moisture gradients, though atmospheric temperature gradients are also not negligible. According to the definition of equivalent potential temperature, and by scale analysis, we find that atmospheric equivalent potential temperature gradients, which could be regarded as an indicator of the Meiyu front system, could be mainly attributed to the variations of atmospheric potential temperature gradients with a scaling factor of 1 and moisture gradients multiplied by a scaling factor of an order of about 2.5 × 103,which means that small variations of atmospheric moisture gradients could lead to large variations of equivalent potential temperature gradients, and thus large variations of the Meiyu front system. Quantitative diagnostics with a mesoscale simulation data in the vicinity of the Meiyu front system show that moisture gradients contribute to equivalent potential temperature gradients more than potential temperature gradients.

  6. Equilibrium statistical mechanics on correlated random graphs

    International Nuclear Information System (INIS)

    Biological and social networks have recently attracted great attention from physicists. Among several aspects, two main ones may be stressed: a non-trivial topology of the graph describing the mutual interactions between agents and, typically, imitative, weighted, interactions. Despite such aspects being widely accepted and empirically confirmed, the schemes currently exploited in order to generate the expected topology are based on a priori assumptions and, in most cases, implement constant intensities for links. Here we propose a simple shift [-1,+1]→[0,+1] in the definition of patterns in a Hopfield model: a straightforward effect is the conversion of frustration into dilution. In fact, we show that by varying the bias of pattern distribution, the network topology (generated by the reciprocal affinities among agents, i.e. the Hebbian rule) crosses various well-known regimes, ranging from fully connected, to an extreme dilution scenario, then to completely disconnected. These features, as well as small-world properties, are, in this context, emergent and no longer imposed a priori. The model is throughout investigated also from a thermodynamics perspective: the Ising model defined on the resulting graph is analytically solved (at a replica symmetric level) by extending the double stochastic stability technique, and presented together with its fluctuation theory for a picture of criticality. Overall, our findings show that, at least at equilibrium, dilution (of whatever kind) simply decreases the strength of the coupling felt by the spins, but leaves the paramagnetic/ferromagnetic flavors unchanged. The main difference with respect to previous investigations is that, within our approach, replicas do not appear: instead of (multi)-overlaps as order parameters, we introduce a class of magnetizations on all the possible subgraphs belonging to the main one investigated: as a consequence, for these objects a closure for a self-consistent relation is achieved

  7. Amplitude growth due to random, correlated kicks

    International Nuclear Information System (INIS)

    Historically, stochastic processes, such as gas scattering or stochastic cooling, have been treated by the Fokker-Planck equation. In this approach, usually considered for one dimension only, the equation can be considered as a continuity equation for a variable which would be a constant of the motion in the absence of the stochastic process, for example, the action variable, I = ε/2π for betatron oscillations, where ε is the area of the Courant-Snyder ellipse, or energy in the case of unbunched beams, or the action variable for phase oscillations in case the beam is bunched. A flux, /Phi/, including diffusive terms can be defined, usually to second order. /Phi/ = M1F(I) + M2∂F/∂I + /hor ellipsis/. M1 and M2 are the expectation values of δI and (δI)2 due to the individual stochastic kicks over some period of time, long enough that the variance of these quantities is sufficiently small. Then the Fokker-Planck equation is just ∂F/∂I + ∂/Phi//∂I = 0. In many cases those where the beam distribution has already achieved its final shape, it is sufficient to find the rate of increase of by taking simple averages over the Fokker-Planck equation. At the time this work was begun, there was good knowledge of the second moment for general stochastic processes due to stochastic cooling theory, but the form of the first moment was known only for extremely wideband processes. The purposes of this note are to derive an expression relating the expected single particle amplitude growth to the noise autocorrelation function and to obtain, thereby, the form of M1 for narrow band processes. 4 refs

  8. Steady-state analysis of a bistable system subject to a coloured multiplicative noise and a white additive noise with coloured cross-correlated noises

    Institute of Scientific and Technical Information of China (English)

    Wang Can-Jun; Chen Shi-Bo; Mei Dong-Cheng

    2006-01-01

    The steady-state properties of a bistable system are investigated when both the multiplicative noise and the coupling between additive and multiplicative noises are coloured with different values of noise correlation times τ1 and 72. After introducing a dimensionless parameter R(R = α/D, D is the intensity of the multiplicative noise and α is the intensity of the additive noise), and performing the numerical computations, we find the following points: (1) For the case ofR > 1, λ (the intensity of correlation between additive and multiplicative noises), τ1 and τ2 can induce the stationary probability distribution (SPD) transition from bimodal to unimodal in structure, but for the cases of R ≤ 1,the bimodal structure is preserved; (2) α can also induce the SPD transition from bimodal to unimodal in structure;(3) the bimodal structure of the SPD exhibits a symmetrical structure as D increases.

  9. The 20th anniversary of interleukin-2 therapy: bimodal role explaining longstanding random induction of complete clinical responses

    OpenAIRE

    Coventry BJ; Ashdown ML

    2012-01-01

    Brendon J Coventry, Martin L AshdownDiscipline of Surgery, University of Adelaide, Royal Adelaide Hospital and Faculty of Medicine, University of Melbourne, AustraliaBackground: This year marks the twentieth anniversary of the approval by the US Food and Drug Administration of interleukin-2 (IL2) for use in cancer therapy, initially for renal cell carcinoma and later for melanoma. IL2 therapy for cancer has stood the test of time, with continued widespread use in Europe, parts of Asia, and th...

  10. The 20th anniversary of interleukin-2 therapy: bimodal role explaining longstanding random induction of complete clinical responses

    International Nuclear Information System (INIS)

    This year marks the twentieth anniversary of the approval by the US Food and Drug Administration of interleukin-2 (IL2) for use in cancer therapy, initially for renal cell carcinoma and later for melanoma. IL2 therapy for cancer has stood the test of time, with continued widespread use in Europe, parts of Asia, and the US. Clinical complete responses are variably reported at 5%–20% for advanced malignant melanoma and renal cell carcinoma, with strong durable responses and sustained long-term 5–10-year survival being typical if complete responses are generated. The literature was reviewed for the actions and clinical effects of IL2 on subsets of T cells. The influence of IL2 on clinical efficacy was also sought. The review revealed that IL2 is capable of stimulating different populations of T cells in humans to induce either T effector or T regulatory responses. This apparent “functional paradox” has confounded a clear understanding of the mechanisms behind the clinical effects that are observed during and following administration of IL2 therapy. An average complete response rate of around 7% in small and large clinical trials using IL2 for advanced renal cell carcinoma and malignant melanoma has been shown from a recent review of the literature. This review considers the published literature concerning the actions and emerging clinical effects of IL2 therapy, spanning its 20-year period in clinical use. It further details some of the recently described “bimodal” effects of IL2 to explain the apparent functional paradox, and how IL2 might be harnessed to emerge rapidly as a much more effective and predictable clinical agent in the near future

  11. Levy flights and random searches

    International Nuclear Information System (INIS)

    In this work we discuss some recent contributions to the random search problem. Our analysis includes superdiffusive Levy processes and correlated random walks in several regimes of target site density, mobility and revisitability. We present results in the context of mean-field-like and closed-form average calculations, as well as numerical simulations. We then consider random searches performed in regular lattices and lattices with defects, and we discuss a necessary criterion for distinguishing true superdiffusion from correlated random walk processes. We invoke energy considerations in relation to critical survival states on the edge of extinction, and we analyze the emergence of Levy behavior in deterministic search walks. Finally, we comment on the random search problem in the context of biological foraging.

  12. Random magnetism

    International Nuclear Information System (INIS)

    The 'ingredients' which control a phase transition in well defined systems as well as in random ones (e.q. random magnetic systems) are listed and discussed within a somehow unifying perspective. Among these 'ingredients' the couplings and elements responsible for the cooperative phenomenon, the topological connectivity as well as possible topological incompatibilities, the influence of new degrees of freedom, the order parameter dimensionality, the ground state degeneracy and finally the 'quanticity' of the system are found. The general trends, though illustrated in magnetic systems, essentially hold for all phase transitions, and give a basis for connection of this area with Field theory, Theory of dynamical systems, etc. (Author)

  13. Random matrices

    CERN Document Server

    Eynard, Bertrand; Ribault, Sylvain

    2015-01-01

    We provide a self-contained introduction to random matrices. While some applications are mentioned, our main emphasis is on three different approaches to random matrix models: the Coulomb gas method and its interpretation in terms of algebraic geometry, loop equations and their solution using topological recursion, orthogonal polynomials and their relation with integrable systems. Each approach provides its own definition of the spectral curve, a geometric object which encodes all the properties of a model. We also introduce the two peripheral subjects of counting polygonal surfaces, and computing angular integrals.

  14. Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J.C.; Ibrahim, S.R.; Brincker, Rune

    Abstraet Thispaper demansirates how to use the Random Decrement (RD) technique for identification o flinear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing a...

  15. Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Ibrahim, S. R.; Brincker, Rune

    This paper demonstrates how to use the Random Decrement (RD) technique for identification of linear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing a new...

  16. Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Ibrahim, R.; Brincker, Rune

    1998-01-01

    This paper demonstrates how to use the Random Decrement (RD) technique for identification of linear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing a new...

  17. Random dynamics

    International Nuclear Information System (INIS)

    The goal of random dynamics is the derivation of the laws of Nature as we know them (standard model) from inessential assumptions. The inessential assumptions made here are expressed as sets of general models at extremely high energies: gauge glass and spacetime foam. Both sets of models lead tentatively to the standard model. (orig.)

  18. Random Vibrations

    Science.gov (United States)

    Messaro. Semma; Harrison, Phillip

    2010-01-01

    Ares I Zonal Random vibration environments due to acoustic impingement and combustion processes are develop for liftoff, ascent and reentry. Random Vibration test criteria for Ares I Upper Stage pyrotechnic components are developed by enveloping the applicable zonal environments where each component is located. Random vibration tests will be conducted to assure that these components will survive and function appropriately after exposure to the expected vibration environments. Methodology: Random Vibration test criteria for Ares I Upper Stage pyrotechnic components were desired that would envelope all the applicable environments where each component was located. Applicable Ares I Vehicle drawings and design information needed to be assessed to determine the location(s) for each component on the Ares I Upper Stage. Design and test criteria needed to be developed by plotting and enveloping the applicable environments using Microsoft Excel Spreadsheet Software and documenting them in a report Using Microsoft Word Processing Software. Conclusion: Random vibration liftoff, ascent, and green run design & test criteria for the Upper Stage Pyrotechnic Components were developed by using Microsoft Excel to envelope zonal environments applicable to each component. Results were transferred from Excel into a report using Microsoft Word. After the report is reviewed and edited by my mentor it will be submitted for publication as an attachment to a memorandum. Pyrotechnic component designers will extract criteria from my report for incorporation into the design and test specifications for components. Eventually the hardware will be tested to the environments I developed to assure that the components will survive and function appropriately after exposure to the expected vibration environments.

  19. Capturing dopaminergic modulation and bimodal membrane behaviour of striatal medium spiny neurons in accurate, reduced models

    Directory of Open Access Journals (Sweden)

    Mark D Humphries

    2009-11-01

    Full Text Available Loss of dopamine from the striatum can cause both profound motor deficits, as in Parkinsons's disease, and disrupt learning. Yet the effect of dopamine on striatal neurons remains a complex and controversial topic, and is in need of a comprehensive framework. We extend a reduced model of the striatal medium spiny neuron (MSN to account for dopaminergic modulation of its intrinsic ion channels and synaptic inputs. We tune our D1 and D2 receptor MSN models using data from a recent large-scale compartmental model. The new models capture the input-output relationships for both current injection and spiking input with remarkable accuracy, despite the order of magnitude decrease in system size. They also capture the paired pulse facilitation shown by MSNs. Our dopamine models predict that synaptic effects dominate intrinsic effects for all levels of D1 and D2 receptor activation. We analytically derive a full set of equilibrium points and their stability for the original and dopamine modulated forms of the MSN model. We find that the stability types are not changed by dopamine activation, and our models predict that the MSN is never bistable. Nonetheless, the MSN models can produce a spontaneously bimodal membrane potential similar to that recently observed in vitro following application of NMDA agonists. We demonstrate that this bimodality is created by modelling the agonist effects as slow, irregular and massive jumps in NMDA conductance and, rather than a form of bistability, is due to the voltage-dependent blockade of NMDA receptors. Our models also predict a more pronounced membrane potential bimodality following D1 receptor activation. This work thus establishes reduced yet accurate dopamine-modulated models of MSNs, suitable for use in large-scale models of the striatum. More importantly, these provide a tractable framework for further study of dopamine's effects on computation by individual neurons.

  20. The geochemistry and petrogenesis of the Paleoproterozoic Green Mountain arc: A composite(?), bimodal, oceanic, fringing arc

    Science.gov (United States)

    Jones, D.S.; Barnes, C.G.; Premo, W.R.; Snoke, A.W.

    2011-01-01

    The inferred subduction affinity of the ~1780-Ma Green Mountain arc, a dominantly bimodal igneous terrane (together with immature marine and volcaniclastic sedimentary rocks) accreted to the southern margin of the Wyoming province, is integral to arc-accretion models of the Paleoproterozoic growth of southern Laurentia. Conversely, the dominantly bimodal nature of many putative arc-related igneous suites throughout southern Laurentia, including the Green Mountain arc, has also been used to support models of growth by extension of pre-existing crust. We report new geochemical and isotopic data from ~1780-Ma gabbroic and granodioritic to tonalitic rocks of the Big Creek Gneiss, interpreted as consanguineous with previously studied metavolcanic rocks of the Green Mountain Formation.The ~1780-Ma Big Creek Gneiss mafic rocks show clear geochemical signatures of a subduction origin and provide no supporting evidence for extensional tectonism. The ~1780-Ma Big Creek Gneiss felsic rocks are attributed to partial melting of mafic and/or mixed lower-crustal material. The bimodal nature of the suite results from the combination of arc basalts and felsic crustal melts. The lack of andesite is consistent with the observed tholeiitic differentiation trend of the mafic magmas. The lower e{open}Nd(1780Ma) values for the felsic rocks vs. the mafic rocks suggest that the unexposed lower crust of the arc may be older than the arc and that Trans-Hudson- or Penokean-aged rocks possibly form the substratum of the arc. Our results reinforce previous interpretations that arc-related magmatism played a key role in the Paleoproterozoic crustal growth of southern Laurentia, but also support the possibility of unexposed older crust as basement to the arcs. ?? 2011 Elsevier B.V.

  1. Improved statistical analysis of low abundance phenomena in bimodal bacterial populations.

    Directory of Open Access Journals (Sweden)

    Friedrich Reinhard

    Full Text Available Accurate detection of subpopulation size determinations in bimodal populations remains problematic yet it represents a powerful way by which cellular heterogeneity under different environmental conditions can be compared. So far, most studies have relied on qualitative descriptions of population distribution patterns, on population-independent descriptors, or on arbitrary placement of thresholds distinguishing biological ON from OFF states. We found that all these methods fall short of accurately describing small population sizes in bimodal populations. Here we propose a simple, statistics-based method for the analysis of small subpopulation sizes for use in the free software environment R and test this method on real as well as simulated data. Four so-called population splitting methods were designed with different algorithms that can estimate subpopulation sizes from bimodal populations. All four methods proved more precise than previously used methods when analyzing subpopulation sizes of transfer competent cells arising in populations of the bacterium Pseudomonas knackmussii B13. The methods' resolving powers were further explored by bootstrapping and simulations. Two of the methods were not severely limited by the proportions of subpopulations they could estimate correctly, but the two others only allowed accurate subpopulation quantification when this amounted to less than 25% of the total population. In contrast, only one method was still sufficiently accurate with subpopulations smaller than 1% of the total population. This study proposes a number of rational approximations to quantifying small subpopulations and offers an easy-to-use protocol for their implementation in the open source statistical software environment R.

  2. Improved statistical analysis of low abundance phenomena in bimodal bacterial populations.

    Science.gov (United States)

    Reinhard, Friedrich; van der Meer, Jan Roelof

    2013-01-01

    Accurate detection of subpopulation size determinations in bimodal populations remains problematic yet it represents a powerful way by which cellular heterogeneity under different environmental conditions can be compared. So far, most studies have relied on qualitative descriptions of population distribution patterns, on population-independent descriptors, or on arbitrary placement of thresholds distinguishing biological ON from OFF states. We found that all these methods fall short of accurately describing small population sizes in bimodal populations. Here we propose a simple, statistics-based method for the analysis of small subpopulation sizes for use in the free software environment R and test this method on real as well as simulated data. Four so-called population splitting methods were designed with different algorithms that can estimate subpopulation sizes from bimodal populations. All four methods proved more precise than previously used methods when analyzing subpopulation sizes of transfer competent cells arising in populations of the bacterium Pseudomonas knackmussii B13. The methods' resolving powers were further explored by bootstrapping and simulations. Two of the methods were not severely limited by the proportions of subpopulations they could estimate correctly, but the two others only allowed accurate subpopulation quantification when this amounted to less than 25% of the total population. In contrast, only one method was still sufficiently accurate with subpopulations smaller than 1% of the total population. This study proposes a number of rational approximations to quantifying small subpopulations and offers an easy-to-use protocol for their implementation in the open source statistical software environment R. PMID:24205184

  3. 'Bimodal' NTR and LANTR propulsion for human missions to Mars/Phobos

    International Nuclear Information System (INIS)

    The nuclear thermal rocket (NTR) is one of the leading propulsion options for future human missions to Mars due to its high specific impulse (Isp ∼850-1000 s) and attractive engine thrust-to-weight ratio (∼3-10). Because only a miniscule amount of enriched uranium-235 fuel is consumed in a NTR during the primary propulsion maneuvers of a typical Mars mission, engines configured for both propulsive thrust and modest power generation (referred to as 'bimodal' operation) provide the basis for a robust, 'power-rich' stage enabling propulsive Mars capture and reuse capability. A family of modular 'bimodal' NTR (BNTR) vehicles are described which utilize a common 'core' stage powered by three 66.7 kN (∼15 klbf) BNTRs that produce 50 kWe of total electrical power for crew life support, an active refrigeration/reliquification system for long term, 'zero-boiloff' liquid hydrogen (LH2) storage, and high data rate communications. Compared to other propulsion options, a Mars mission architecture using BNTR transfer vehicles requires fewer transportation system elements which reduces mission mass, cost and risk because of simplified space operations. For difficult Mars options, such as a Phobos rendezvous and sample return mission, volume (not mass) constraints limit the performance of the 'all LH2' BNTR stage. The use of ''LOX-augmented' NTR (LANTR) engines, operating at a modest oxygen-to-hydrogen (O/H) mixture ratio (MR) of 0.5, helps to increase 'bulk' propellant density and total thrust during the trans-Mars injection (TMI) burn. On all subsequent burns, the bimodal LANTR engines operate on LH2 only (MR=0) to maximize vehicle performance while staying within the mass limits of two ∼80 t 'Magnum' heavy lift launch vehicles (HLLVs)

  4. On a Symmetric, Nonlinear Birth-Death Process with Bimodal Transition Probabilities

    Directory of Open Access Journals (Sweden)

    Barbara Martinucci

    2009-11-01

    Full Text Available We consider a bilateral birth-death process having sigmoidal-type rates. A thorough discussion on its transient behaviour is given, which includes studying symmetry properties of the transition probabilities, finding conditions leading to their bimodality, determining mean and variance of the process, and analyzing absorption problems in the presence of 1 or 2 boundaries. In particular, thanks to the symmetry properties we obtain the avoiding transition probabilities in the presence of a pair of absorbing boundaries, expressed as a series.

  5. Engineering three-dimensional maximally entangled states for two modes in a bimodal cavity

    Institute of Scientific and Technical Information of China (English)

    Yang Zhen-Biao; Su Wan-Jun

    2007-01-01

    An alternative scheme is proposed for engineering three-dimensional maximally entangled states for two modes of a superconducting microwave cavity. In this scheme, an appropriately prepared four-level atom is sent through a bimodal cavity. During its passing through the cavity, the atom is coupled resonantly with two cavity modes simultaneously and addressed by a classical microwave pulse tuned to the required transition. Then the atomic states are detected to collapse two modes onto a three-dimensional maximally entangled state. The scheme is different from the previous one in which two nonlocal cavities are used. A comparison between them is also made.

  6. Bulge-Disk Decompositions and Structural Bimodality of Ursa Major Cluster Spiral Galaxies

    OpenAIRE

    McDonald, Michael; Courteau, Stephane; Tully, R. Brent

    2008-01-01

    We present bulge and disk (B/D) decompositions of existing K'-band surface brightness profiles for 65 Ursa Major cluster spiral galaxies. This improves upon the disk-only fits of Tully et al. (1996). The 1996 disk fits were used by Tully & Verheijen (1997) for their discovery of the bimodality of structural parameters in the UMa cluster galaxies. It is shown that our new 1D B/D decompositions yield disk structural parameters that differ only slightly from the basic fits of Tully et al. and ev...

  7. Accuracy of a teleported trapped field state inside a single bimodal cavity

    International Nuclear Information System (INIS)

    We propose a simplified scheme to teleport a superposition of coherent states from one mode to another of the same bimodal lossy cavity. Based on current experimental capabilities, we present a calculation of the fidelity that can be achieved, demonstrating accurate teleportation if the mean photon number of each mode is at most 1.5. Our scheme applies as well for teleportation of coherent states from one mode of a cavity to another mode of a second cavity, when both cavities are embedded in a common reservoir

  8. Parallel Bimodal Bilingual Acquisition : A Hearing Child Mediated in a Deaf Family

    OpenAIRE

    Cramér-Wolrath, Emelie

    2013-01-01

    The aim of this longitudinal case study was to describe bimodal and bilingual acquisition in a hearing child, Hugo, and in what ways these were guided by his Deaf family. Video observations of the family interactions were conducted from Hugo’s age of 10 months until he was 40 months old. The family language was Swedish Sign Language (SSL). With Hugo, however, the parents used one language base in which single gestural signs or vocal words were often simultaneously inserted, the latter when no...

  9. Time shift in slope failure prediction between unimodal and bimodal modeling approaches

    Science.gov (United States)

    Ciervo, Fabio; Casini, Francesca; Nicolina Papa, Maria; Medina, Vicente

    2016-04-01

    Together with the need to use more appropriate mathematical expressions for describing hydro-mechanical soil processes, a challenge issue relates to the need of considering the effects induced by terrain heterogeneities on the physical mechanisms, taking into account the implications of the heterogeneities in affecting time-dependent hydro-mechanical variables, would improve the prediction capacities of models, such as the ones used in early warning systems. The presence of the heterogeneities in partially-saturated slopes results in irregular propagation of the moisture and suction front. To mathematically represent the "dual-implication" generally induced by the heterogeneities in describing the hydraulic terrain behavior, several bimodal hydraulic models have been presented in literature and replaced the conventional sigmoidal/unimodal functions; this presupposes that the scale of the macrostructure is comparable with the local scale (Darcy scale), thus the Richards' model can be assumed adequate to mathematically reproduce the processes. The purpose of this work is to focus on the differences in simulating flow infiltration processes and slope stability conditions originated from preliminary choices of hydraulic models and contextually between different approaches to evaluate the factor of safety (FoS). In particular, the results of two approaches are compared. The first one includes the conventional expression of the FoS under saturated conditions and the widespread used hydraulic model of van Genuchten-Mualem. The second approach includes a generalized FoS equation for infinite-slope model under variably saturated soil conditions (Lu and Godt, 2008) and the bimodal Romano et al.'s (2011) functions to describe the hydraulic response. The extension of the above mentioned approach to the bimodal context is based on an analytical method to assess the effects of the hydraulic properties on soil shear developed integrating a bimodal lognormal hydraulic function

  10. Bi-Modal Person Recognition on a Mobile Phone: using mobile phone data

    OpenAIRE

    McCool, Chris; Marcel, Sébastien; Hadid, Abdenour; Pietikainen, Matti; Matejka, Pavel; Cernocky, Jan; Poh, Norman; Kittler, J.; Larcher, Anthony; Levy, Christophe; Matrouf, Driss; Bonastre, Jean-François; Tresadern, Phil; Cootes, Timothy

    2012-01-01

    This paper presents a novel fully automatic bi-modal, face and speaker, recognition system which runs in real-time on a mobile phone. The implemented system runs in real-time on a Nokia N900 and demonstrates the feasibility of performing both automatic face and speaker recognition on a mobile phone. We evaluate this recognition system on a novel publicly-available mobile phone database and provide a well defined evaluation protocol. This database was captured almost exclusively using mobile p...

  11. Impact of Bimodal Traffic on Latency in Optical Burst Switching Networks

    Directory of Open Access Journals (Sweden)

    Yuhua Chen

    2008-01-01

    Full Text Available This paper analyzes the impact of bimodal traffic composition on latency in optical burst switching networks. In particular, it studies the performance degradation to short-length packets caused by longer packets, both of which are part of a heterogeneous traffic model. The paper defines a customer satisfaction index for each of the classes of traffic, and a composite satisfaction index. The impact of higher overall utilization of the network as well as that of the ratio of the traffic mix on each of the customer satisfaction indices is specifically addressed.

  12. Facile Synthesis and Photocatalytic Property of Titania/Carbon Composite Hollow Microspheres with Bimodal Mesoporous Shells

    OpenAIRE

    Guohong Wang; Bei Cheng; Jun Zhang; Lin Xu; Tingting Yin

    2012-01-01

    Titania/carbon composite hollow microspheres with bimodal mesoporous shells are one-pot fabricated by hydrothermal treatment of the acidic (NH4)2TiF6 aqueous solution in the presence of glucose at 180∘C for 24 h and then calcined at 450∘C. The as-prepared samples were characterized by XRD, SEM, TEM, HRTEM, UV-visible spectroscopy, and nitrogen adsorption-desorption isotherms. The photocatalytic activity of the as-prepared samples was evaluated by daylight-induced photocatalytic decolorization...

  13. Development of Bimodal Grain Structures in Nb-Containing High-Strength Low-Alloy Steels during Slab Reheating

    Science.gov (United States)

    Chakrabarti, Debalay; Davis, Claire; Strangwood, Martin

    2008-08-01

    Bimodal (mixed coarse and fine) grain structures, which have been observed in some Nb-containing thermomechanically-controlled rolled steel plates, adversely affect their mechanical properties by causing scatter in cleavage fracture stress values. It is known that bimodal grain structures can develop during reheating prior to rolling; however, no quantitative predictions of the level of bimodality or the critical reheat temperatures for formation have been reported. In this article, three high-strength low-alloy (HSLA) steel slabs with varying microalloying additions (Ti, Nb, and V) have been characterized in the as-continuously cast and reheated (to various temperatures in the range 1050 °C to 1225 °C) conditions to determine the link between their grain size distribution (and any bimodality observed) and the microalloy precipitate type, size, and distribution. The as-cast slabs showed inhomogeneous microalloying precipitate distributions with the separation between precipitate-rich and precipitate-poor regions being consistent with interdendritic segregation and hence, the secondary dendrite arm spacing (SDAS). The susceptibility of the slabs to the formation of bimodality, based on the steel chemical compositions and critical reheat temperature ranges has been identified, both experimentally and theoretically using ThermoCalc (Thermo-Calc Software, Stockholm, Sweden) modeling of precipitate stability in the solute-rich and the solute-depleted regions formed during casting.

  14. Scaling and root planning and locally delivered minocycline could reduce the load of Prevotella intermedia in an interdependent pattern, which correlated with symptomatic improvements of chronic periodontitis: a short-term randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Deng S

    2015-12-01

    Full Text Available Shuli Deng,1 Ying Wang,1 Wei Sun,1 Hui Chen,1 Gang Wu2 1Department of Conservative Dentistry, Affiliated Hospital of Stomatology, Medical College, Zhejiang University, Hangzhou, People’s Republic of China; 2Department of Oral Implantology and Prosthetic Dentistry, Academic Centre for Dentistry Amsterdam (ACTA, VU University Amsterdam and University of Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, the Netherlands Background: To evaluate the respective or combinatory efficacy of locally delivered 2% minocycline (MO and scaling and root planning (SRP by assessing both clinical parameters and the loads of four main periodontal pathogens in treating chronic periodontitis (CP.Methods: Seventy adults with CP were randomly assigned to the three treatment groups: 1 SRP alone; 2 MO alone; and 3 combinatory use of SRP and MO (SRP + MO. Before and 7 days after the treatments, we evaluated both clinical parameters (pocket depth [PD] and sulcus bleeding index [SBI] and the gene load of four main periodontal pathogens (Aggregatibacter actinomycetemcomitans [Aa], Fusobacterium nucleatum [Fn], Porphyromonas gingivalis [Pg], and Prevotella intermedia [Pi].Results: The bacterial prevalence per patient was Aa, 31.25%; Fn, 100%; Pg, 95.31%; and Pi, 98.44%. Seven days after treatments, the three treatments could significantly reduce both PD and SBI, but not detection frequencies of the four pathogens. For PD, the reduction efficacy of SRP + MO was significantly higher than that of both MO and SRP. Only Pg responded significantly to SRP. Pg and Fn could be significantly reduced in the presence of MO. Only SRP + MO but not the respective showed a significant reduction effect on the gene load of Pi. The reduction of PD significantly correlated with the gene load of Pi (r=0.26; P=0.042 but not of the other bacteria.Conclusion: SRP and MO could reduce the load of Pi in an interdependent pattern, which correlated with symptomatic improvements of CP

  15. A Mathematical Model of Bimodal Epigenetic Control of miR-193a in Ovarian Cancer Stem Cells

    Science.gov (United States)

    Kochańczyk, Marek; Lin, Jora M. J.; Chen, Gary C. W.; Lai, Hung-Cheng; Nephew, Kenneth P.; Hwang, Tzy-Wei; Chan, Michael W. Y.

    2014-01-01

    Accumulating data indicate that cancer stem cells contribute to tumor chemoresistance and their persistence alters clinical outcome. Our previous study has shown that ovarian cancer may be initiated by ovarian cancer initiating cells (OCIC) characterized by surface antigen CD44 and c-KIT (CD117). It has been experimentally demonstrated that a microRNA, namely miR-193a, targets c-KIT mRNA for degradation and could play a crucial role in ovarian cancer development. How miR-193a is regulated is poorly understood and the emerging picture is complex. To unravel this complexity, we propose a mathematical model to explore how estrogen-mediated up-regulation of another target of miR-193a, namely E2F6, can attenuate the function of miR-193a in two ways, one through a competition of E2F6 and c-KIT transcripts for miR-193a, and second by binding of E2F6 protein, in association with a polycomb complex, to the promoter of miR-193a to down-regulate its transcription. Our model predicts that this bimodal control increases the expression of c-KIT and that the second mode of epigenetic regulation is required to generate a switching behavior in c-KIT and E2F6 expressions. Additional analysis of the TCGA ovarian cancer dataset demonstrates that ovarian cancer patients with low expression of EZH2, a polycomb-group family protein, show positive correlation between E2F6 and c-KIT. We conjecture that a simultaneous EZH2 inhibition and anti-estrogen therapy can constitute an effective combined therapeutic strategy against ovarian cancer. PMID:25545504

  16. A mathematical model of bimodal epigenetic control of miR-193a in ovarian cancer stem cells.

    Directory of Open Access Journals (Sweden)

    Frank H C Cheng

    Full Text Available Accumulating data indicate that cancer stem cells contribute to tumor chemoresistance and their persistence alters clinical outcome. Our previous study has shown that ovarian cancer may be initiated by ovarian cancer initiating cells (OCIC characterized by surface antigen CD44 and c-KIT (CD117. It has been experimentally demonstrated that a microRNA, namely miR-193a, targets c-KIT mRNA for degradation and could play a crucial role in ovarian cancer development. How miR-193a is regulated is poorly understood and the emerging picture is complex. To unravel this complexity, we propose a mathematical model to explore how estrogen-mediated up-regulation of another target of miR-193a, namely E2F6, can attenuate the function of miR-193a in two ways, one through a competition of E2F6 and c-KIT transcripts for miR-193a, and second by binding of E2F6 protein, in association with a polycomb complex, to the promoter of miR-193a to down-regulate its transcription. Our model predicts that this bimodal control increases the expression of c-KIT and that the second mode of epigenetic regulation is required to generate a switching behavior in c-KIT and E2F6 expressions. Additional analysis of the TCGA ovarian cancer dataset demonstrates that ovarian cancer patients with low expression of EZH2, a polycomb-group family protein, show positive correlation between E2F6 and c-KIT. We conjecture that a simultaneous EZH2 inhibition and anti-estrogen therapy can constitute an effective combined therapeutic strategy against ovarian cancer.

  17. Approximations to the Probability of Failure in Random Vibration by Integral Equation Methods

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Sørensen, John Dalsgaard

    Close approximations to the first passage probability of failure in random vibration can be obtained by integral equation methods. A simple relation exists between the first passage probability density function and the distribution function for the time interval spent below a barrier before outcr...... passage probability density. The results of the theory agree well with simulation results for narrow banded processes dominated by a single frequency, as well as for bimodal processes with 2 dominating frequencies in the structural response....

  18. Pollination, mating and reproductive fitness in a plant population with bimodal floral-tube length.

    Science.gov (United States)

    Anderson, B; Pauw, A; Cole, W W; Barrett, S C H

    2016-08-01

    Mating patterns and natural selection play important roles in determining whether genetic polymorphisms are maintained or lost. Here, we document an atypical population of Lapeirousia anceps (Iridaceae) with a bimodal distribution of floral-tube length and investigate the reproductive mechanisms associated with this pattern of variation. Flowers were visited exclusively by the long-proboscid fly Moegistorhynchus longirostris (Nemestrinidae), which exhibited a unimodal distribution of proboscis length and displayed a preference for long-tubed phenotypes. Despite being visited by a single pollinator species, allozyme markers revealed significant genetic differentiation between open-pollinated progeny of long- and short-tubed phenotypes suggesting mating barriers between them. We obtained direct evidence for mating barriers between the floral-tube phenotypes through observations of pollinator foraging, controlled hand pollinations and measurements of pollen competition and seed set. Intermediate tube-length phenotypes produced fewer seeds in the field than either long- or short-tubed phenotypes. Although floral-tube length bimodality may not be a stable state over long timescales, reproductive barriers to mating and low 'hybrid' fitness have the potential to contribute to the maintenance of this state in the short term. PMID:27206242

  19. Study of the magnetorheology of aqueous suspensions of extremely bimodal magnetite particles

    Science.gov (United States)

    Viota, J. L.; Durán, J. D. G.; Delgado, A. V.

    2009-05-01

    In this paper we describe the magnetorheological behavior of aqueous suspensions consisting of magnetite particles of two size populations, in the micrometer and nanometer scale, respectively. Previous works on the magnetorheology of oil-based fluids demonstrated that the addition of nanoparticles has a very significant effect on the intensity of the magnetorheological effect. The present contribution confirms such results in the case of aqueous fluids, based on the dependence of the yield stress and the viscosity of the bimodal suspensions on both the composition of the mixtures and the magnetic field strength. It is demonstrated that for a given concentration of micrometer particles, increasing the amount of nanometer magnetite provokes a clear enhancement in the yield stress for all the magnetic fields applied. This is proposed to be due to the formation of heterogeneous aggregates that improve the stability of the suspensions and ease the building of well-arranged field-induced structures. The behavior of both the yield stress and the post-yield viscosity agrees better with the predictions of standard chain models when the relative proportion of both types of particles confers optimum stability to the bimodal dispersions.

  20. Bimodal mortality dynamics for uveal melanoma: a cue for metastasis development traits?

    International Nuclear Information System (INIS)

    The study estimates mortality dynamics (event-specific hazard rates over a follow-up time interval) for uveal melanoma. Three thousands six hundred seventy two patients undergoing radical or conservative treatment for unilateral uveal melanoma, whose yearly follow-up data were reported in three published datasets, were analysed. Mortality dynamics was studied by estimating with the life-table method the discrete hazard rate for death. Smoothed curves were obtained by a Kernel-like smoothing procedure and a piecewise exponential regression model. The ratio deaths/patients at risk per year was the main outcome measure. The three explored hazard rate curves display a common bimodal pattern, with a sudden increase peaking at about three years, followed by reduction until the sixth-seventh year and a second surge peaking at about nine years after treatment. The bimodal pattern of mortality indicates that uveal melanoma metastatic development cannot be explained by a continuous growth model. Similar metastasis dynamics have been reported for other tumours, including early breast cancer, for which it supported a paradigm shift to an interrupted growth model, the implications of which are episodes of ‘tumour dormancy’. We propose that the concepts of tumour homeostasis, tumour dormancy and enhancement of metastasis growth related to primary tumour removal, convincingly explaining the clinical behaviour of breast cancer, may be used for uveal melanoma as well. To confirm this proposition, a careful analysis of uveal melanoma metastasis dynamics is strongly warranted

  1. Bimodal fibrous structures for tissue engineering: Fabrication, characterization and in vitro biocompatibility.

    Science.gov (United States)

    Tiwari, Arjun Prasad; Joshi, Mahesh Kumar; Kim, Jeong In; Unnithan, Afeesh Rajan; Lee, Joshua; Park, Chan Hee; Kim, Cheol Sang

    2016-08-15

    We report for the first time a polycaprolactone-human serum albumin (PCL-HSA) membrane with bimodal structures comprised of spider-web-like nano-nets and conventional fibers via facile electro-spinning/netting (ESN) technique. Such unique controllable morphology was developed by electrospinning the blend solution of PCL (8wt% in HFIP 1,1,1,3,3,3,-Hexafluoro-2-propanol) and HSA (10wt% deionized water). The phase separation during electrospinning caused the formation of bimodal structure. Various processing factors such as applied voltage, feeding rate, and distance between nozzle tip and collector were found responsible for the formation and distribution of the nano-nets throughout the nanofibrous mesh. Field emission electron microscopy (FE-SEM) confirmed that the nano-nets were composed of interlinked nanowires with an ultrathin diameter (10-30nm). When compared with a pure PCL membrane, the membrane containing nano-nets was shown to have better support for cellular activities as determined by cell viability and attachment assays. These results revealed that the blending of albumin, a hydrophilic biomolecule, with PCL, a hydrophobic polymer, proves to be an outstanding approach to developing membranes with controlled spider-web-like nano-nets for tissue engineering. PMID:27179176

  2. Bimodality in binary Au + Au collisions from 60 to 100 MeV/u

    Energy Technology Data Exchange (ETDEWEB)

    Pichon, M.; Tamain, B.; Bougault, R. [Caen Univ., Lab. de Physique Corpusculaire, IN2P3-CNRS, ISMRA, 14 (France)] [and others

    2003-03-01

    The deexcitation of quasi-projectiles (QP) released in binary Au on Au collisions as been studied from 60 to 100 MeV/u. Bimodality between two different decay patterns has been observed for intermediate violence collisions. The main experimental result is that the system jumps from one mode to the other on a narrow range of energy deposit and/or impact parameter. The sorting of the events (according to the violence of the collision) has been provided by the perpendicular energy of the light charged particles emitted on the quasi-target side. Such a sorting prevents spurious autocorrelation effects between the sorting variable and the observed mechanism. The two modes of the QP decay correspond on the one side to residue or fission fragments production, and on the other side to the multifragmentation channel. A detailed study has been performed in order to try to establish the origin of the observed bimodality in disentangling dynamical or geometrical effects from bulk matter properties linked with a liquid-gas type phase transition. The whole set of data is coherent with a dominant role of the deposited excitation energy as it is expected from theoretical arguments.(lattice gas model) in the framework of a liquid-gas phase transition picture. (authors)

  3. Efficient and reusable polyamide-56 nanofiber/nets membrane with bimodal structures for air filtration.

    Science.gov (United States)

    Liu, Bowen; Zhang, Shichao; Wang, Xueli; Yu, Jianyong; Ding, Bin

    2015-11-01

    Nanofibrous media that both possess high airborne particle interception efficiency and robust air permeability would have broad technological implications for areas ranging from individual protection and industrial security to environmental governance; however, creating such filtration media has proved extremely challenging. Here we report a strategy to construct the bio-based polyamide-56 nanofiber/nets (PA-56 NFN) membranes with bimodal structures for effective air filtration via one-step electrospinning/netting. The PA-56 membranes are composed of completely covered two-dimensional (2D) ultrathin (∼20 nm) nanonets which are optimized by facilely regulating the solution concentration, and the bonded scaffold fibers constructed cavity structures which are synchronously created by using the CH3COOH inspiration. With integrated properties of small aperture, high porosity, and bonded scaffold, the resulting PA-56 NFN membranes exhibit high filtration efficiency of 99.995%, low pressure drop of 111 Pa, combined with large dust holding capacity of 49 g/m(2) and dust-cleaning regeneration ability, for filtrating ultrafine airborne particles in the most safe manner involving sieving principle and surface filtration. The successful synthesis of PA-56 NFN medium would not only make it a promising candidate for air filtration, but also provide new insights into the design and development of nanonet-based bimodal structures for various applications. PMID:26188726

  4. Bimodality of light and s-elements in M4 (NGC 6121)

    CERN Document Server

    Villanova, Sandro

    2011-01-01

    All Globular Clusters (GCs) studied in detail so far host two or more populations of stars. Theoretical models suggest that the second population is formed from gas polluted by processed material produced by massive stars of the first generation. However the nature of the polluter is a matter of strong debate. Several candidates have been proposed: massive main-sequence stars (fast rotating or binaries), intermediate-mass AGB stars, or SNeII. We studied red giant branch (RGB) stars in the GC M4 (NGC 6121) to measure their chemical signature. We confirm the presence of a bimodal population, first discovered by Marino et al. (2008). The two groups have different C,$^{12}$C/$^{13}$C,N,O,Na content, but share the same Li,C+N+O,Mg,Al,Si,Ca,Ti,Cr,Fe,Ni,Zr,Ba and Eu abundance. Quite surprisingly the two groups differ also in their Y abundance. The absence of a spread in $\\alpha$-elements, Eu and Ba makes SNeII and AGB stars unlikely as polluters. On the other hand, massive main-sequence stars can explain the bimodal...

  5. Timing of seed dispersal generates a bimodal seed bank depth distribution.

    Science.gov (United States)

    Espinar, José L; Thompson, Ken; García, Luis V

    2005-10-01

    The density of soil seed banks is normally highest at the soil surface and declines monotonically with depth. Sometimes, for a variety of reasons, peak density occurs below the surface but, except in severely disturbed soils, it is generally true that deeper seeds are older. In seasonally dry habitats that develop deep soil cracks during the dry season, it is possible that some seeds fall down cracks and rapidly become deeply buried. We investigated this possibility for three dominant clonal perennials (Scirpus maritimus, S. litoralis, and Juncus subulatus) in the Doñana salt marsh, a nontidal marsh with a Mediterranean climate located in southwest Spain. Two species, which shed most of their seed during the dry season and have seeds with low buoyancy, had bimodal viable seed depth distributions, with peak densities at the surface and at 16-20 cm. A third species, which shed most seeds after soil cracks had closed and had seeds with high buoyancy, had viable seeds only in surface soil. Bimodal seed bank depth distributions may be relatively common in seasonally dry habitats with fine-textured soils, but their ecological significance has not been investigated. PMID:21646093

  6. Human Exploration Mission Capabilities to the Moon, Mars, and Near Earth Asteroids Using ''Bimodal'' NTR Propulsion

    International Nuclear Information System (INIS)

    The nuclear thermal rocket (NTR) is one of the leading propulsion options for future human exploration missions because of its high specific impulse (Isp ∼ 850 to 1000 s) and attractive engine thrust-to-weight ratio (∼ 3 to 10). Because only a minuscule amount of enriched 235U fuel is consumed in an NRT during the primary propulsion maneuvers of a typical Mars mission, engines configured both for propulsive thrust and modest power generation (referred to as 'bimodal' operation) provide the basis for a robust, power-rich stage with efficient propulsive capture capability at the moon and near-earth asteroids (NEAs), where aerobraking cannot be utilized. A family of modular bimodal NTR (BNTR) space transfer vehicles utilize a common core stage powered by three ∼15-klbf engines that produce 50 kW(electric) of total electrical power for crew life support, high data rate communications with Earth, and an active refrigeration system for long-term, zero-boiloff liquid hydrogen (LH2) storage. This paper describes details of BNTR engines and designs of vehicles using them for various missions

  7. Bimodal regime in young massive clusters leading to subsequent stellar generations

    CERN Document Server

    Wünsch, Richard; Tenorio-Tagle, Guillermo; Muñoz-Tuñón, Casiana; Ehlerová, Soňa

    2016-01-01

    Massive stars in young massive clusters insert tremendous amounts of mass and energy into their surroundings in the form of stellar winds and supernova ejecta. Mutual shock-shock collisions lead to formation of hot gas, filling the volume of the cluster. The pressure of this gas then drives a powerful cluster wind. However, it has been shown that if the cluster is massive and dense enough, it can evolve in the so--called bimodal regime, in which the hot gas inside the cluster becomes thermally unstable and forms dense clumps which are trapped inside the cluster by its gravity. We will review works on the bimodal regime and discuss the implications for the formation of subsequent stellar generations. The mass accumulates inside the cluster and as soon as a high enough column density is reached, the interior of the clumps becomes self-shielded against the ionising radiation of stars and the clumps collapse and form new stars. The second stellar generation will be enriched by products of stellar evolution from t...

  8. Anhydrides-Cured Bimodal Rubber-Like Epoxy Asphalt Composites: From Thermosetting to Quasi-Thermosetting

    Directory of Open Access Journals (Sweden)

    Yang Kang

    2016-03-01

    Full Text Available The present engineering practices show the potential that epoxy asphalt composites (EACs would be a better choice to obtain long life for busy roads. To understand the service performance–related thermorheological properties of prepared bimodal anhydrides-cured rubber-like EACs (REACs, a direct tensile tester, dynamic shear rheometer and mathematical model were used. Tensile tests demonstrate that all the REACs reported here are more flexible than previously reported anhydrides-cured REACs at both 20 and 0 °C. The better flexibility is attributed to the change of bimodal networks, in which cross-linked short chains decreased and cross-linked long chains increased, relatively. Strain sweeps show that all the REACs have linear viscoelastic (LVE properties when their strains are smaller than 1.0% from −35 to 120 °C. Temperature sweeps illustrate that the thermorheological properties of REACs evolve from thermosetting to quasi-thermosetting with asphalt content, and all the REACs retain solid state and show elastic properties in the experimental temperature range. A Cole–Cole plot and Black diagram indicate that all the REACs are thermorheologically simple materials, and the master curves were constructed and well-fitted by the Generalized Logistic Sigmoidal models. This research provides a facile approach to tune the thermorheological properties of the REACs, and the cheaper quasi-thermosetting REAC facilitates their advanced applications.

  9. High temperature tensile properties and fracture characteristics of bimodal 12Cr-ODS steel

    Science.gov (United States)

    Chauhan, Ankur; Litvinov, Dimitri; Aktaa, Jarir

    2016-01-01

    This article describes the tensile properties and fracture characteristics of a 12Cr oxide dispersion strengthened (ODS) ferritic steel with unique elongated bimodal grain size distribution. The tensile tests were carried out at four different temperatures, ranging from room temperature to 700 °C, at a nominal strain rate of 10-3 s-1. At room temperature the material exhibits a high tensile strength of 1294 MPa and high yield strength of 1200 MPa. At 700 °C, the material still exhibits relatively high tensile strength of 300 MPa. The total elongation-to-failure exceeds 18% over the whole temperature range and has a maximum value of 29% at 600 °C. This superior ductility is attributed to the material's bimodal grain size distribution. In comparison to other commercial, as well as experimental, ODS steels, the material shows an excellent compromise between strength and ductility. The fracture surface studies reveal a change in fracture behavior from a mixed mode fracture at room temperature to fully ductile fracture at 600 °C. At 700 °C, the fracture path changes from intragranular to intergranular fracture, which is associated with a reduced ductility.

  10. Bimodality in binary Au + Au collisions from 60 to 100 MeV/u

    International Nuclear Information System (INIS)

    The deexcitation of quasi-projectiles (QP) released in binary Au on Au collisions as been studied from 60 to 100 MeV/u. Bimodality between two different decay patterns has been observed for intermediate violence collisions. The main experimental result is that the system jumps from one mode to the other on a narrow range of energy deposit and/or impact parameter. The sorting of the events (according to the violence of the collision) has been provided by the perpendicular energy of the light charged particles emitted on the quasi-target side. Such a sorting prevents spurious autocorrelation effects between the sorting variable and the observed mechanism. The two modes of the QP decay correspond on the one side to residue or fission fragments production, and on the other side to the multifragmentation channel. A detailed study has been performed in order to try to establish the origin of the observed bimodality in disentangling dynamical or geometrical effects from bulk matter properties linked with a liquid-gas type phase transition. The whole set of data is coherent with a dominant role of the deposited excitation energy as it is expected from theoretical arguments.(lattice gas model) in the framework of a liquid-gas phase transition picture. (authors)

  11. Top-down and bottom-up modulation in processing bimodal face/voice stimuli

    Directory of Open Access Journals (Sweden)

    VanRullen Rufin

    2010-03-01

    Full Text Available Abstract Background Processing of multimodal information is a critical capacity of the human brain, with classic studies showing bimodal stimulation either facilitating or interfering in perceptual processing. Comparing activity to congruent and incongruent bimodal stimuli can reveal sensory dominance in particular cognitive tasks. Results We investigated audiovisual interactions driven by stimulus properties (bottom-up influences or by task (top-down influences on congruent and incongruent simultaneously presented faces and voices while ERPs were recorded. Subjects performed gender categorisation, directing attention either to faces or to voices and also judged whether the face/voice stimuli were congruent in terms of gender. Behaviourally, the unattended modality affected processing in the attended modality: the disruption was greater for attended voices. ERPs revealed top-down modulations of early brain processing (30-100 ms over unisensory cortices. No effects were found on N170 or VPP, but from 180-230 ms larger right frontal activity was seen for incongruent than congruent stimuli. Conclusions Our data demonstrates that in a gender categorisation task the processing of faces dominate over the processing of voices. Brain activity showed different modulation by top-down and bottom-up information. Top-down influences modulated early brain activity whereas bottom-up interactions occurred relatively late.

  12. Three Stages of Mesozoic Bimodal Igneous Rocks and Their Tectonic Implications on the Continental Margin of Southeastern China

    Institute of Scientific and Technical Information of China (English)

    XING Guangfu; YANG Zhuliang; CHEN Rong; SHEN Jialin; WEI Naiyi; ZHOU Yuzhang

    2004-01-01

    There are large-scale Mesozoic bimodal igneous rock associations on the continental margin of southeastern China. They aroused extensive attention in the 1980s because of their specific tectonic implications, and have been found frequently during recent geological surveys. This paper reviews the studies of regional Mesozoic bimodal rocks, and concludes that they can be subdivided into three stages, i.e., the Early Jurassic (209-170 Ma, the first (Ⅰ) stage), the Late Jurassic-early Early Cretaceous (154-121 Ma, the second (Ⅱ) stage), and the late Early Cretaceous-Late Cretaceous (115-85 Ma, the third (Ⅲ) stage). These three stages of bimodal rocks were formed in different tectonic settings, and are important indicators for regional Mesozoic tectonic evolution.

  13. Bimodal distribution characteristic of microstructure and mechanical properties of nanostructured composite ceramic coatings prepared by supersonic plasma spraying

    International Nuclear Information System (INIS)

    Highlights: • The microstructure of NCs exhibited a bimodal distribution. • The proportions of FM and PM regions both increased with spray power increasing. • The mechanical properties followed Weibull distribution. - Abstract: Nanostructured composite ceramic coatings (NCs) were deposited by supersonic plasma spraying (SPS) technique. The microstructures of NCs were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The results showed that the microstructure of NCs exhibited a bimodal distribution consisting of fully melted regions (FM regions) and partially melted regions (PM regions). With the spray power increasing, the proportions of FM regions and PM regions both increased, but no distinct laws were found. The measured data of elastic modulus, micro-hardness and fracture toughness were analyzed using Weibull statistics. The results showed that these micromechanical properties followed Weibull distribution and presented a characteristic of bimodal distribution

  14. Influence of age, spatial memory, and ocular fixation on localization of auditory, visual, and bimodal targets by human subjects.

    Science.gov (United States)

    Dobreva, Marina S; O'Neill, William E; Paige, Gary D

    2012-12-01

    A common complaint of the elderly is difficulty identifying and localizing auditory and visual sources, particularly in competing background noise. Spatial errors in the elderly may pose challenges and even threats to self and others during everyday activities, such as localizing sounds in a crowded room or driving in traffic. In this study, we investigated the influence of aging, spatial memory, and ocular fixation on the localization of auditory, visual, and combined auditory-visual (bimodal) targets. Head-restrained young and elderly subjects localized targets in a dark, echo-attenuated room using a manual laser pointer. Localization accuracy and precision (repeatability) were quantified for both ongoing and transient (remembered) targets at response delays up to 10 s. Because eye movements bias auditory spatial perception, localization was assessed under target fixation (eyes free, pointer guided by foveal vision) and central fixation (eyes fixed straight ahead, pointer guided by peripheral vision) conditions. Spatial localization across the frontal field in young adults demonstrated (1) horizontal overshoot and vertical undershoot for ongoing auditory targets under target fixation conditions, but near-ideal horizontal localization with central fixation; (2) accurate and precise localization of ongoing visual targets guided by foveal vision under target fixation that degraded when guided by peripheral vision during central fixation; (3) overestimation in horizontal central space (±10°) of remembered auditory, visual, and bimodal targets with increasing response delay. In comparison with young adults, elderly subjects showed (1) worse precision in most paradigms, especially when localizing with peripheral vision under central fixation; (2) greatly impaired vertical localization of auditory and bimodal targets; (3) increased horizontal overshoot in the central field for remembered visual and bimodal targets across response delays; (4) greater vulnerability to

  15. Effect of the bimodality of a QD array on the optical properties and threshold characteristics of QD lasers

    Energy Technology Data Exchange (ETDEWEB)

    Nadtochiy, A. M., E-mail: al.nadtochy@mail.ioffe.ru [Russian Academy of Sciences, St. Petersburg Academic University, Nanotechnology Research and Education Centre (Russian Federation); Mintairov, S. A.; Kalyuzhnyy, N. A. [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Rouvimov, S. S. [University of Notre Dame (United States); Shernyakov, Yu. M. [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Payusov, A. S.; Maximov, M. V.; Zhukov, A. E. [Russian Academy of Sciences, St. Petersburg Academic University, Nanotechnology Research and Education Centre (Russian Federation)

    2015-08-15

    Heterostructures with InGaAs quantum dots (QDs) are synthesized on vicinal GaAs (001) substrates. The photoluminescence (PL) spectra and threshold characteristics of edge-emitting QD lasers are studied in the temperature range 10-400 K. The structural properties of QDs are examined by transmission electron microscopy. Analysis of the PL spectra demonstrates the bimodality of the QD array, which leads to an unusual temperature behavior of the PL spectra and threshold current density. A model of the population of a bimodal QD array by carriers, describing the observed phenomena, is considered.

  16. Effect of the bimodality of a QD array on the optical properties and threshold characteristics of QD lasers

    International Nuclear Information System (INIS)

    Heterostructures with InGaAs quantum dots (QDs) are synthesized on vicinal GaAs (001) substrates. The photoluminescence (PL) spectra and threshold characteristics of edge-emitting QD lasers are studied in the temperature range 10-400 K. The structural properties of QDs are examined by transmission electron microscopy. Analysis of the PL spectra demonstrates the bimodality of the QD array, which leads to an unusual temperature behavior of the PL spectra and threshold current density. A model of the population of a bimodal QD array by carriers, describing the observed phenomena, is considered

  17. Symmetric Gini Covariance and Correlation

    OpenAIRE

    Sang, Yongli; Dang, Xin; Sang, Hailin

    2016-01-01

    Standard Gini covariance and Gini correlation play important roles in measuring the dependence of random variables with heavy tails. However, the asymmetry brings a substantial difficulty in interpretation. In this paper, we propose a symmetric Gini-type covariance and a symmetric Gini correlation ($\\rho_g$) based on the joint rank function. The proposed correlation $\\rho_g$ is more robust than the Pearson correlation but less robust than the Kendall's $\\tau$ correlation. We establish the rel...

  18. Framework for testing random numbers in parallel calculations

    DEFF Research Database (Denmark)

    Vattulainen, Ilpo Tapio

    1999-01-01

    We propose a framework for testing the quality of random numbers in parallel calculations. The key idea. is to study cross-correlations between distinct sequences of random numbers via correlations between various diffusing random walkers, each of which is governed by a distinct random number seq...... efficient tests. which find correlations in various commonly used pseudorandom number generators. Finally, we discuss some ideas for applying this framework in other contexts. [S1063-651X(99)05106-5]....

  19. Correlated Noise Effects on Gene Expression

    Institute of Scientific and Technical Information of China (English)

    王先菊; 艾保全; 刘国涛; 刘良钢

    2003-01-01

    Based on the model describing the regulation of the PRM operator region of λ phage proposed by Hasty et al.[Proc. Nat. Acad. Sci. 97(2000)2075], we study the steady-state probability distribution properties of the model in the presence of correlated Gaussian white noise. We find that the degree of correlation of the noises can affect the form of the steady-state probability distribution. When the degree of correlation of the noises increases, the form of the steady-state probability distribution changes from a bimodal into a unimodal structure.The steady-state probability distribution extrema have also been investigated. We find that noise correlation can change the positions of the extreme value of the steady-state probability distribution of the model greatly.

  20. Learning efficient correlated equilibria

    KAUST Repository

    Borowski, Holly P.

    2014-12-15

    The majority of distributed learning literature focuses on convergence to Nash equilibria. Correlated equilibria, on the other hand, can often characterize more efficient collective behavior than even the best Nash equilibrium. However, there are no existing distributed learning algorithms that converge to specific correlated equilibria. In this paper, we provide one such algorithm which guarantees that the agents\\' collective joint strategy will constitute an efficient correlated equilibrium with high probability. The key to attaining efficient correlated behavior through distributed learning involves incorporating a common random signal into the learning environment.

  1. INFORMATION ON THE MILKY WAY FROM THE 2MASS ALL SKY STAR COUNT: BIMODAL COLOR DISTRIBUTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chan-Kao; Lai, Shao-Yu; Peng, Ting-Hung [Institute of Astronomy, National Central University, Jhongli, Taiwan (China); Ko, Chung-Ming, E-mail: rex@astro.ncu.edu.tw, E-mail: cmko@astro.ncu.edu.tw [Institute of Astronomy, Department of Physics and Center of Complex Systems, National Central University, Jhongli, Taiwan (China)

    2012-11-10

    The J - K{sub s} color distributions (CDs) with a bin size of 0.05 mag has been carried out for the entire Milky Way using the Two Micron All Sky Survey Point Source Catalog (2MASS PSC). The CDs are bimodal, with a red peak at 0.8 < J - K{sub s} < 0.85 and a blue peak at 0.3 < J - K{sub s} < 0.4. The colors of the red peak are more or less the same for the whole sky, but those of the blue peak depend on Galactic latitude (J - K{sub s} {approx} 0.35 at low Galactic latitudes and 0.35 < J - K{sub s} < 0.4 for other sky areas). The blue peak dominates the bimodal CDs at low Galactic latitudes and becomes comparable with the red peak in other sky regions. In order to explain the bimodal distribution and the global trend shown by the all-sky 2MASS CDs, we assemble an empirical Hertzsprung-Russell (H-R) diagram, which is composed of observational-based near-infrared H-R diagrams and color-magnitude diagrams, and incorporate a Milky Way model. In the empirical H-R diagram, the main-sequence turn-off for stars in the thin disk is relatively bluer, (J - K{sub s} ){sub 0} = 0.31, compared with that of the thick disk which is (J - K{sub s} ){sub 0} = 0.39. The age of the thin/thick disk is roughly estimated to be around 4-5/8-9 Gyr according to the color-age relation of the main-sequence turn-off. In general, the 2MASS CDs can be treated as a tool to measure the age of the stellar population of the Milky Way in a statistical manner and to our knowledge it is the first attempt to do so.

  2. Elevation of circulating HLA DR+ CD8+ T-cells and correlation with chromium and cobalt concentrations 6 years after metal-on-metal hip arthroplasty : a randomized trial

    OpenAIRE

    Hailer, Nils P.; Blaheta, Roman A; Dahlstrand, Henrik; Stark, André

    2011-01-01

    Background and purpose Following metal-on-metal hip arthroplasty (THA), immunological reactions including changes in lymphocyte populations, aseptic loosening, and lymphocytic pseudotumors occur. We hypothesized that changes in lymphocyte subpopulations would be associated with elevated metal ion concentrations. Methods A randomized trial involving 85 patients matched for age and sex and randomized to receiving metal-on-metal (n = 41) or metal-on-polyethylene total hip arthroplasty (n = 44) w...

  3. A random matrix approach to credit risk.

    Science.gov (United States)

    Münnix, Michael C; Schäfer, Rudi; Guhr, Thomas

    2014-01-01

    We estimate generic statistical properties of a structural credit risk model by considering an ensemble of correlation matrices. This ensemble is set up by Random Matrix Theory. We demonstrate analytically that the presence of correlations severely limits the effect of diversification in a credit portfolio if the correlations are not identically zero. The existence of correlations alters the tails of the loss distribution considerably, even if their average is zero. Under the assumption of randomly fluctuating correlations, a lower bound for the estimation of the loss distribution is provided. PMID:24853864

  4. Bimodal momentum distribution of laser-cooled atoms in optical lattices

    CERN Document Server

    Dion, Claude M; Kastberg, Anders; Sjölund, Peder

    2016-01-01

    We study, numerically and experimentally, the momentum distribution of atoms cooled in optical lattices. Using semi-classical simulations, we show that this distribution is bimodal, made up of a central feature corresponding to "cold", trapped atoms, with tails of "hot", untrapped atoms, and that this holds true also for very shallow potentials. Careful analysis of the distribution of high-momentum untrapped atoms, both from simulations and experiments, shows that the tails of the distribution does not follow a normal law, hinting at a power-law distribution and non-ergodic behavior. We also revisit the phenomenon of d\\'ecrochage, the potential depth below which the temperature of the atoms starts increasing.

  5. Bimodal momentum distribution of laser-cooled atoms in optical lattices

    Science.gov (United States)

    Dion, Claude M.; Jonsell, Svante; Kastberg, Anders; Sjölund, Peder

    2016-05-01

    We study, numerically and experimentally, the momentum distribution of atoms cooled in optical lattices. Using semiclassical simulations, we show that this distribution is bimodal, made up of a central feature corresponding to "cold," trapped atoms, with tails of "hot," untrapped atoms, and that this holds true also for very shallow potentials. Careful analysis of the distribution of high-momentum untrapped atoms, both from simulations and experiments, shows that the tails of the distribution do not follow a normal law, hinting at a power-law distribution and nonergodic behavior. We also revisit the phenomenon leading to the existence of an optimal cooling point, i.e., a potential depth below which the temperature of the atoms starts increasing.

  6. Fabrication and Dealloying Behavior of Monolithic Nanoporous Copper Ribbons with Bimodal Channel Size Distributions

    Institute of Scientific and Technical Information of China (English)

    Wenbo Liu; Shichao Zhang; Ning Li; Jiwei Zheng; Yalan Xing

    2012-01-01

    Monolithic nanoporous copper (NPC) ribbons with bimodal channel size distributions can be fabricated through chemical dealloying of Mg-32 Cu alloy in an acidic solution at room temperature. The microstructure of the as- dealloyed samples was characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis. These NPC ribbons are composed of interconnected large-sized channels (hundreds of nm) with highly porous channel walls (tens of nm). Both large- and small-sized channels are open, bicontinuous, and interpenetrating. Additionally, it is the first time to find that the evolution process of porous structure along the thickness direction of samples during the dealloying is from the interior to exterior, which is just contrary to the coarsening process along the thickness direction during the post-dealloying. Meanwhile, the corresponding mechanism is discussed in detail.

  7. Carboniferous Bimodal Volcanic Rocks and Their Plate Tectonic Setting,Hainan Island

    Institute of Scientific and Technical Information of China (English)

    夏邦栋; 施光宇; 等

    1992-01-01

    The Carboniferous volcanic rocks in western Hainan Island consist of a series of oceanic tholeite and rhyoporphyrite,showing bimodal nature.Similar geochemical characters,in terms of abun-daces and relative rations of incompatible elements and REE and the REE patterns,between the basalt and continental rift-associated tholeiite indicate the occurrence of Late Paleozoic rifting in the area.The basaltic magma,with a low degree of evolution,was originated from deep mantle,show-ing contamination by low crustal material.The rhyolite is thought to be formed from partial melting of the continental crust by higher thermal flow in a rift environment rather than from fractional crystallization of a basaltic magma.

  8. Synthesis and tuning of bimodal mesoporous silica by combined hydrocarbon/fluorocarbon surfactant templating.

    Science.gov (United States)

    Xing, Rong; Lehmler, Hans-Joachim; Knutson, Barbara L; Rankin, Stephen E

    2009-06-01

    Hydrocarbon and fluorocarbon surfactants show highly nonideal mixing that under some conditions results in demixing of the two types of surfactants into distinct populations of fluorocarbon-rich and hydrocarbon-rich aggregates. This also occurs in materials prepared by cooperative assembly of hydrolyzed tetraethoxysilane with mixtures of cetyltrimethylammonium chloride (CTAC) and 1,1,2,2-tetrahydro-perfluorodecylpyridinium chloride (HFDePC). Here, we report conditions under which demixed micelles lead to bimodal mesoporous materials (including specific concentrations of ammonia and salt in the synthesis solution) and show that the sizes of the hydrocarbon-templated and fluorocarbon-templated pores can be finely and independently controlled by adding lipophilic or fluorophilic oils, respectively. Nitrogen sorption isotherms and transmission electron microscopy provide clear evidence for a single phase of demixed but disordered wormhole-like pores. PMID:19323503

  9. Decoupled polarization dynamics of incoherent waves and bimodal spectral incoherent solitons.

    Science.gov (United States)

    Fusaro, A; Garnier, J; Michel, C; Xu, G; Fatome, J; Wright, L G; Wise, F W; Picozzi, A

    2016-09-01

    We consider the propagation of strongly incoherent waves in optical fibers in the framework of the vector nonlinear Schrödinger equation (VNLSE) accounting for the Raman effect. On the basis of the wave turbulence theory, we derive a kinetic equation that greatly simplifies the VNLSE and provides deep physical insight into incoherent wave dynamics. When applied to the study of polarization effects, the theory unexpectedly reveals that the linear polarization components of the incoherent wave evolve independently from each other, even in the presence of weak fiber birefringence. When applied to light propagation in bimodal fibers, the theory reveals that the incoherent modal components can be strongly coupled. After a complex transient, the modal components self-organize into a vector spectral incoherent soliton: The two solitons self-trap and propagate with a common velocity in frequency space. PMID:27607955

  10. Labeling and Selective Inactivation of Gram-Positive Bacteria Employing Bimodal Photoprobes with Dual Readouts.

    Science.gov (United States)

    Galstyan, Anzhela; Block, Desiree; Niemann, Silke; Grüner, Malte C; Abbruzzetti, Stefania; Oneto, Michele; Daniliuc, Constantin G; Hermann, Sven; Viappiani, Cristiano; Schäfers, Michael; Löffler, Bettina; Strassert, Cristian A; Faust, Andreas

    2016-04-01

    Carbohydrate-conjugated silicon(IV) phthalocyanines with bimodal photoactivity were developed as probes with both fluorescent labeling and photosensitizing capabilities, and the concomitant fluorescent labeling and photoinduced inactivation of Gram-positive and Gram-negative models was explored. The maltohexaose-conjugated photoprobe provides a dual readout to distinguish between both groups of pathogens, as only the Gram-positive species was inactivated, even though both appeared labeled with near-infrared luminescence. Antibiotic resistance did not hinder the phototoxic effect, as even the methicillin-resistant pathogen Staphylococcus aureus (MRSA) was completely photoinactivated. Time-resolved confocal fluorescence microscopy analysis suggests that the photoprobe sticks onto the outer rim of the microorganisms, explaining the resistance of Gram-negative species on the basis of their membrane constitution. The mannose-conjugated photoprobe yields a different readout because it is able to label and to inactivate only the Gram-positive strain. PMID:26929124

  11. Magnetic complexity as an explanation for bimodal rotation populations among young stars

    CERN Document Server

    Garraffo, Cecilia; Cohen, Ofer

    2015-01-01

    Observations of young open clusters have revealed a bimodal distribution of fast and slower rotation rates that has proven difficult to explain with predictive models of spin down that depend on rotation rates alone. The Metastable Dynamo Model proposed recently by Brown, employing a stochastic transition probability from slow to more rapid spin down regimes, appears to be more successful but lacks a physical basis for such duality. Using detailed 3D MHD wind models computed for idealized multipole magnetic fields, we show that surface magnetic field complexity can provide this basis. Both mass and angular momentum losses decline sharply with increasing field complexity. Combined with observation evidence for complex field morphologies in magnetically active stars, our results support a picture in which young, rapid rotators lose angular momentum in an inefficient way because of field complexity. During this slow spin-down phase, magnetic complexity is eroded, precipitating a rapid transition from weak to str...

  12. Magnetic Complexity as an Explanation for Bimodal Rotation Populations among Young Stars

    Science.gov (United States)

    Garraffo, Cecilia; Drake, Jeremy J.; Cohen, Ofer

    2015-07-01

    Observations of young open clusters have revealed a bimodal distribution of fast and slower rotation rates that has proven difficult to explain with predictive models of spin down that depend on rotation rates alone. The Metastable Dynamo Model proposed recently by Brown, employing a stochastic transition probability from slow to more rapid spin down regimes, appears to be more successful but lacks a physical basis for such duality. Using detailed 3D MHD wind models computed for idealized multipole magnetic fields, we show that surface magnetic field complexity can provide this basis. Both mass and angular momentum losses decline sharply with increasing field complexity. Combined with observation evidence for complex field morphologies in magnetically active stars, our results support a picture in which young, rapid rotators lose angular momentum in an inefficient way because of field complexity. During this slow spin-down phase, magnetic complexity is eroded, precipitating a rapid transition from weak to strong wind coupling.

  13. Gd-containing conjugated polymer nanoparticles: bimodal nanoparticles for fluorescence and MRI imaging

    Science.gov (United States)

    Hashim, Zeina; Green, Mark; Chung, Pei Hua; Suhling, Klaus; Protti, Andrea; Phinikaridou, Alkystis; Botnar, Rene; Khanbeigi, Raha Ahmad; Thanou, Maya; Dailey, Lea Ann; Nicola J., Commander; Rowland, Caroline; Scott, Jo; Jenner, Dominic

    2014-06-01

    Aqueous bifunctional semiconductor polymer nanoparticles (SPNs), approximately 30 nm in diameter (as measured from electron microscopy), were synthesised using hydrophobic conjugated polymers, amphiphilic phospholipids and a gadolinium-containing lipid. Their fluorescence quantum yields and extinction coefficients were determined, and their MRI T1-weighted relaxation times in water were measured. The bimodal nanoparticles were readily taken up by HeLa and murine macrophage-like J774 cells as demonstrated by confocal laser scanning microscopy, and were found to be MRI-active, generating a linear relationship between T1-weighted relaxation rates and gadolinium concentrations The synthesis is relatively simple, and can easily result in milligrams of materials, although we fully expect scale-up to the gram level to be easily realised.

  14. Bimodality and re-entrant behaviour in the hierarchical self-assembly of polymeric nanoparticles.

    Science.gov (United States)

    C K, Sarika; Tomar, Gaurav; Basu, J K; Thiele, Uwe

    2015-12-14

    We show that a film of a suspension of polymer grafted nanoparticles on a liquid substrate can be employed to create two-dimensional nanostructures with a remarkable variation in the pattern length scales. The presented experiments also reveal the emergence of concentration-dependent bimodal patterns as well as re-entrant behaviour that involves length scales due to dewetting and compositional instabilities. The experimental observations are explained through a gradient dynamics model consisting of coupled evolution equations for the height of the suspension film and the concentration of polymer. Using a Flory-Huggins free energy functional for the polymer solution, we show in a linear stability analysis that the thin film undergoes dewetting and/or compositional instabilities depending on the concentration of the polymer in the solution. We argue that the formation via 'hierarchical self-assembly' of various functional nanostructures observed in different systems can be explained as resulting from such an interplay of instabilities. PMID:26406929

  15. Superferromagnetism in mechanically alloyed fcc Fe23Cu77 with bimodal cluster size distribution

    International Nuclear Information System (INIS)

    Magnetic measurements, x-ray diffraction and Moessbauer spectroscopy were used to characterize a nanostructured fcc Fe23Cu77 at.% alloy prepared by high-energy ball-milling, addressing in particular the effect of clustering on the nature of the interacting magnetic entities. The interpretation of magnetization measurements leads to the conclusion that grains, whose mean size is ∼16 nm, contain two populations of magnetic Fe-rich nanoclusters with a bimodal size distribution. These two sets of clusters contain about 14 and 400 Fe atoms and have magnetic moments of 30 μB and 860 μB, respectively. The inter-cluster ferromagnetic interactions that lead to superferromagnetism with a Curie temperature TC∼220 K can be described by a mean field determined by the smaller clusters only, which account for 90% of the magnetization.

  16. Bimodal behaviour of charge carriers in graphene induced by electric double layer

    Science.gov (United States)

    Tsai, Sing-Jyun; Yang, Ruey-Jen

    2016-07-01

    A theoretical investigation is performed into the electronic properties of graphene in the presence of liquid as a function of the contact area ratio. It is shown that the electric double layer (EDL) formed at the interface of the graphene and the liquid causes an overlap of the conduction bands and valance bands and increases the density of state (DOS) at the Fermi energy (EF). In other words, a greater number of charge carriers are induced for transport and the graphene changes from a semiconductor to a semimetal. In addition, it is shown that the dependence of the DOS at EF on the contact area ratio has a bimodal distribution which responses to the experimental observation, a pinnacle curve. The maximum number of induced carriers is expected to occur at contact area ratios of 40% and 60%. In general, the present results indicate that modulating the EDL provides an effective means of tuning the electronic properties of graphene in the presence of liquid.

  17. Unimodular bimode gravity and the coherent scalar-graviton field as galaxy dark matter

    CERN Document Server

    Pirogov, Yu F

    2011-01-01

    The explicit violation of general relativity is adopted as an origin of dark matter and dark energy of the gravitational nature. The violation of the local scale invariance alone, with the residual unimodular invariance/relativity, is considered as a paradigm. Besides the four-volume preserving deformation mode -- the transverse-tensor graviton -- the metric comprises a compression mode -- the scalar graviton, or the {\\em systolon}. The unimodular invariant metric theory of the bimode gravity is worked out. Due to a non-dynamical scalar density -- the dark {\\em modulus} -- the theory is general covariant. To substantially reduce the primordial ambiguity of the effective Lagrangian a dynamical global symmetry -- the {\\em compression} one -- is superimposed at the classical level, with the subsequent spontaneous breaking of the symmetry displayed. The static spherically symmetric field configuration in the empty, but possibly for the origin, space is studied. A three-parameter solution describing a new static s...

  18. Hypoxia tolerance and partitioning of bimodal respiration in the striped catfish (Pangasianodon hypophthalmus)

    DEFF Research Database (Denmark)

    Lefevre, Sjannie; Huong, Do Thi Thanh; Wang, Tobias;

    2011-01-01

    , gill ventilation and air-breathing frequency were measured in a separate experiment with pressure measurements from the buccal cavity. The data showed that P. hypophthalmus is able to maintain standard metabolic rate (SMR) through aquatic breathing alone in normoxia, but that air-breathing is important......Air-breathing fish are common in the tropics, and their importance in Asian aquaculture is increasing, but the respiratory physiology of some of the key species such as the striped catfish, Pangasianodon hypophthalmus Sauvage 1878 is unstudied. P. hypophthalmus is an interesting species...... as it appears to possess both well-developed gills and a modified swim bladder that functions as an air-breathing organ indicating a high capacity for both aquatic and aerial respiration. Using newly developed bimodal intermittent-closed respirometry, the partitioning of oxygen consumption in normoxia...

  19. Assessment of an SP-100 bi-modal propulsion and power system

    Science.gov (United States)

    Buksa, J. J.; Demuth, S.; Huber, T.

    1993-02-01

    The attractiveness of using the SP-100 space nuclear power system for both electric power production and direct thermal propulsion is discussed. A conceptual modification to the SP-100 generic flight system that uses its hot, primary coolant to directly heat hydrogen propellant is presented. An analytical model of the system and its orbital-mechanical behavior is presented and used to assess the benefits of a number of orbital transfer missions. Both a 500 kW and a 2.4 MW system are assessed. Preliminary results indicate that for LEO-to-GEO transfers, the SP-100 bimodal system offers a 100% increase in payload over conventional chemical-only propulsion systems with transfer times on the order of days.

  20. On the existence, uniqueness and nature of Caratheodory and Filippov solutions for bimodal piecewise affine dynamical systems

    NARCIS (Netherlands)

    Le Quang, Thuan; Camlibel, M. K.

    2014-01-01

    In this paper, we deal with the well-posedness (in the sense of existence and uniqueness of solutions) and nature of solutions for discontinuous bimodal piecewise affine systems in a differential inclusion setting. First, we show that the conditions guaranteeing uniqueness of Filippov solutions in t

  1. Insight into the structural mechanism of the bi-modal action of an NCAM mimetic, the C3 peptide

    DEFF Research Database (Denmark)

    Kiselyov, Vladislav V; Li, Shizhong; Berezin, Vladimir;

    2009-01-01

    proposed. In one of them, the FGFR Ig2-Ig3 modules are involved in binding to NCAM, whereas in another - the FGFR "acid box" region mediates the interaction. The bi-modal effect of C3 can be explained in the context of the former model and is not consistent with the latter, thus providing evidence in...

  2. A scheme for conditional quantum phase gate via bimodal cavity and a Λ-type three-level atom

    Institute of Scientific and Technical Information of China (English)

    Cai Jian-Wu; Fang Mao-Fa; Liao Xiang-Ping; Zheng Xiao-Juan

    2006-01-01

    We propose a scheme to implement a two-qubit conditional quantum phase gate for the intracavity field via a single three-level Λ-type atom driven by two modes in a high-Q cavity. The quantum information is encoded on the Fock states of the bimodal cavity. The gate's averaged fidelity is expected to reach 99.8%.

  3. SWRC fit - a nonlinear fitting program with a water retention curve for soils having unimodal and bimodal pore structure

    Science.gov (United States)

    Seki, K.

    2007-02-01

    The soil hydraulic parameters for analyzing soil water movement can be determined by fitting a soil water retention curve to a certain function, i.e., a soil hydraulic model. For this purpose, the program "SWRC Fit," which performs nonlinear fitting of soil water retention curves to 5 models by Levenberg-Marquardt method, was developed. The five models are the Brooks and Corey model, the van Genuchten model, Kosugi's log-normal pore-size distribution model, Durner's bimodal pore-size distribution model, and a bimodal log-normal pore-size distribution model propose in this study. This program automatically determines all the necessary conditions for the nonlinear fitting, such as the initial estimate of the parameters, and, therefore, users can simply input the soil water retention data to obtain the necessary parameters. The program can be executed directly from a web page at http://purl.org/net/swrc/; a client version of the software written in numeric calculation language GNU Octave is included in the electronic supplement of this paper. The program was used for determining the soil hydraulic parameters of 420 soils in UNSODA database. After comparing the root mean square error of the unimodal models, the van Genuchten and Kosugi's models were better than the Brooks and Corey model. The bimodal log-normal pore-size distribution model had similar fitting performance to Durner's bimodal pore-size distribution model.

  4. SWRC fit – a nonlinear fitting program with a water retention curve for soils having unimodal and bimodal pore structure

    Directory of Open Access Journals (Sweden)

    K. Seki

    2007-02-01

    Full Text Available The soil hydraulic parameters for analyzing soil water movement can be determined by fitting a soil water retention curve to a certain function, i.e., a soil hydraulic model. For this purpose, the program "SWRC Fit," which performs nonlinear fitting of soil water retention curves to 5 models by Levenberg-Marquardt method, was developed. The five models are the Brooks and Corey model, the van Genuchten model, Kosugi's log-normal pore-size distribution model, Durner's bimodal pore-size distribution model, and a bimodal log-normal pore-size distribution model propose in this study. This program automatically determines all the necessary conditions for the nonlinear fitting, such as the initial estimate of the parameters, and, therefore, users can simply input the soil water retention data to obtain the necessary parameters. The program can be executed directly from a web page at http://purl.org/net/swrc/; a client version of the software written in numeric calculation language GNU Octave is included in the electronic supplement of this paper. The program was used for determining the soil hydraulic parameters of 420 soils in UNSODA database. After comparing the root mean square error of the unimodal models, the van Genuchten and Kosugi's models were better than the Brooks and Corey model. The bimodal log-normal pore-size distribution model had similar fitting performance to Durner's bimodal pore-size distribution model.

  5. Head Shadow, Squelch, and Summation Effects with an Energetic or Informational Masker in Bilateral and Bimodal CI Users

    Science.gov (United States)

    Pyschny, Verena; Landwehr, Markus; Hahn, Moritz; Lang-Roth, Ruth; Walger, Martin; Meister, Hartmut

    2014-01-01

    Purpose: The objective of the study was to investigate the influence of noise (energetic) and speech (energetic plus informational) maskers on the head shadow (HS), squelch (SQ), and binaural summation (SU) effect in bilateral and bimodal cochlear implant (CI) users. Method: Speech recognition was measured in the presence of either a competing…

  6. The Impact of Bimodal Bilingual Parental Input on the Communication and Language Development of a Young Deaf Child

    Science.gov (United States)

    Levesque, Elizabeth; Brown, P. Margaret; Wigglesworth, Gillian

    2014-01-01

    This study explores the impact of bimodal bilingual parental input on the communication and language development of a young deaf child. The participants in this case study were a severe-to-profoundly deaf boy and his hearing parents, who were enrolled in a bilingual (English and Australian Sign Language) homebased early intervention programme. The…

  7. Simulation of the Brownian coagulation of nanoparticles with initial bimodal size distribution via moment method

    Institute of Scientific and Technical Information of China (English)

    Jian-Zhong Lin; Fu-Jun Gan

    2012-01-01

    The Brownian coagulation of nanoparticles with initial bimodal size distribution,i.e.,mode i and j,is numerically studied using the moment method.Evolutions of particle number concentration,geometric average diameter and geometric standard deviation are given in the free molecular regime,the continuum regime,the free molecular regimand transition regime,the free molecular regime and contin-uum regime,respectively.The results show that,both in the free molecular regime and the continuum regime,the number concentration of mode i and j decreases with increasing time.The evolutions of particle geometric average diameter with different initial size distribution are quite different.Both intra-modal and inter-modal coagulation finally make the polydispersed size distribution become monodispersed.As time goes by,the size distribution with initial bimodal turns to be unimodal and shifts to a larger particle size range.In the free molecular regime and transition regime,the intermodal coagulation becomes dominant when the number concentrations of mode i and j are of the same order.The effects of the number concentration of mode i and mode j on the evolution of geometric average diameter of mode j are negligible,while the effects of the number concentration of mode j on the evolution of geometric average diameter of mode j is distinct.In the free molecular regime and continuum regime,the higher the initial number concentration of mode j,the more obvious the variation of the number concentration of mode i.

  8. X-Ray Diffraction Microstructural Analysis of Bimodal-Size-Distribution MgO Nanopowders

    Science.gov (United States)

    Pratapa, Suminar; Hartono, Budi

    2010-01-01

    Investigation on the characteristics of x-ray diffraction data for MgO powdered mixture of nano and sub-nano particles has been carried out to reveal the crystallite-size-related microstructural information. The MgO powders were prepared by co-precipitation method followed by heat treatment at 500, 800 and 1200° C for 1 hour, being the difference in the temperature was to obtain two powders with distinct crystallite size and size-distribution. The powders were then carefully blended in air to give the presumably strain-free, bimodal-size-distribution MgO nanopowder. High-quality laboratory X-ray diffraction data for the powders were collected and then analysed using Rietveld-based MAUD software using the lognormal size distribution. Results show that the single-mode powders exhibit spherical crystallite size (Dv) of 29(1) nm, 36(1) and 185(0) nm for the 500, 800 and 1200° C data respectively with the nanometric powder displays slightly narrower crystallite size distribution character, indicated by lognormal dispersion parameter (σ) of 0.22 as compared to 0.18 for the sub-nanometric 1200° C powder. The mixture exhibits relatively more asymmetric peak broadening. By analysing the x-ray diffraction data of the latter specimen by using the single phase approach the results obtained was not according to experimental finding. Introducing two phase models for the `double-phase' 500-1200 mixture to accommodate the bimodal-size-distribution characteristics give Dv = 34(2) and σ = 0.10 for the `nanometric phase' and Dv = 363(0) and σ = 1.38 for the `sub-nanometric phase'.

  9. Evidence for a bimodal size distribution for the suspended aerosol particles on Mars

    Science.gov (United States)

    Fedorova, A. A.; Montmessin, F.; Rodin, A. V.; Korablev, O. I.; Määttänen, A.; Maltagliati, L.; Bertaux, J.-L.

    2014-03-01

    First simultaneous analysis of the ultraviolet (UV) and infrared (IR) atmospheric extinctions from SPICAM/Mars Express solar occultations in the beginning of the Northern summer (Ls = 56-97°) is presented. The two SPICAM channels allow sounding of the martian atmosphere in the spectral range from 0.118 to 1.7 μm at the altitudes from 10 to 80 km. Based on Mie scattering theory with adequate refraction indices for dust and H2O ice, a bimodal distribution of aerosol has been inferred from the SPICAM measurements. The coarser mode is represented by both dust and H2O particles with average radius of 0.7 and 1.2 μm, respectively, with number density from 0.01 to 10 particles in cm3. Clouds belonging to the aphelion cloud belt have been observed in midlatitudes in the Southern and the Northern hemispheres at altitudes of 20-30 km. The clouds are formed of large particles, and their opacity in the UV and the IR is below 0.03. The finer mode with a radius of 0.04-0.07 μm and a number density from 1 cm-3 at 60 km to 1000 cm-3 at 20 km has been detected in both hemispheres. In the Southern hemisphere the finer mode extends up to 70 km, whereas in the Northern hemisphere it is confined below 30-40 km. The lack of condensation nuclei is consistent, but could not fully explain the high water supersaturation observed between 30 and 50 km in the same Northern hemisphere dataset (Maltagliati L., Montmessin, F., Fedorova, A., Korablev, O., Forget, F., Bertaux, J.-L. [2011]. Science 333, 1868-1871). The average size of the fine mode (∼50 nm) and the large number density (up to 1000 cm-3) most likely corresponds to Aitken particles (r survival of the observed bimodal distribution.

  10. Development of a steady state creep behavior model of polycrystalline tungsten for bimodal space reactor application

    Energy Technology Data Exchange (ETDEWEB)

    Purohit, A.; Hanan, N.A.; Bhattacharyya, S.K.; Gruber, E.E.

    1995-02-01

    The fuel element for one of the many reactor concepts being currently evaluated for bimodal applications in space consists of spherical fuel particles clad with tungsten or alloys of tungsten. The fuel itself consists of stabilized UO{sub 2}. One of the life limiting phenomena for the fuel element is failure of the cladding because of creep deformation. This report summarizes the information available in literature regarding the creep deformation of tungsten and its alloys and proposes a relation to be used for calculating the creep strains for elevated temperatures in the low stress region ({sigma} {le} 20 MPa). Also, results of the application of this creep relation to one of the reactor design concepts (NEBA-3) are discussed. Based on the traditional definition of creep deformation, the temperatures of 1500 K to 2900 K for tungsten and its alloys are considered to be in the {open_quotes}high{close_quotes} temperature range. In this temperature range, the rate controlling mechanisms for creep deformation are believed to be non-conservative motion of screw dislocations and short circuit diffusional paths. Extensive theoretical work on creep and in particular for creep of tungsten and its alloys have been reported in the literature. These theoretical efforts have produced complex mathematical models that require detailed materials properties. These relations, however, are not presently suitable for the creep analysis because of lack of consistent material properties required for their use. Variations in material chemistry and thermomechanical pre-treatment of tungsten have significant effects on creep and the mechanical properties. Analysis of the theoretical models and limited data indicates that the following empirical relation originally proposed by M. Jacox of INEL and the Air Force Phillips Laboratory, for calculating creep deformation of tungsten cladding, can be used for the downselection of preliminary bimodal reactor design concepts.

  11. X-ray diffraction microstructural analysis of bimodal size distribution MgO nano powder

    International Nuclear Information System (INIS)

    Investigation on the characteristics of x-ray diffraction data for MgO powdered mixture of nano and sub-nano particles has been carried out to reveal the crystallite-size-related microstructural information. The MgO powders were prepared by co-precipitation method followed by heat treatment at 500 degree Celsius and 1200 degree Celsius for 1 hour, being the difference in the temperature was to obtain two powders with distinct crystallite size and size-distribution. The powders were then blended in air to give the presumably bimodal-size- distribution MgO nano powder. High-quality laboratory X-ray diffraction data for the powders were collected and then analysed using Rietveld-based MAUD software using the lognormal size distribution. Results show that the single-mode powders exhibit spherical crystallite size (R) of 20(1) nm and 160(1) nm for the 500 degree Celsius and 1200 degree Celsius data respectively with the nano metric powder displays narrower crystallite size distribution character, indicated by lognormal dispersion parameter of 0.21 as compared to 0.01 for the sub-nano metric powder. The mixture exhibits relatively more asymmetric peak broadening. Analysing the x-ray diffraction data for the latter specimen using single phase approach give unrealistic results. Introducing two phase models for the double-phase mixture to accommodate the bimodal-size-distribution characteristics give R = 100(6) and σ = 0.62 for the nano metric phase and R = 170(5) and σ= 0.12 for the σ sub-nano metric phase. (author)

  12. Effect of meta-carborane on segmental dynamics in a bimodal Poly(dimethylsiloxane) network

    Energy Technology Data Exchange (ETDEWEB)

    Lewicki, J; Maxwell, R S; Patel, M; Herberg, J; Swain, A C; Liggat, J; Pethrick, R

    2008-06-11

    Bimodal networks of polydimethylsiloxane (PDMS) filled with varying amounts of icosahedral meta-carborane (m-CB) have been developed and characterized by broadband dielectric spectroscopy (BDS) and static {sup 1}H Multiple Quantum Nuclear Magnetic Resonance (MQ NMR). Both BDS and MQ NMR showed evidence for a decrease in the polymer chain dynamics. BDS spectra quantified a normal-mode relaxation near 40 Hz at 40 C. The frequency maximum observed for filled samples decreased with increasing m-CB content until contents greater than 5 wt. %. The width of the relaxation spectrum increased with the addition of small quantities of filler and decreased with filler contents greater that 5 wt. %. Agglomeration effects were observed at loadings greater than 5 wt % as manifest by the onset of low frequency Maxwell-Wagner-Sillars (MWS) processes. The MQ NMR data allowed the characterization of distributions of the residual dipolar couplings, <{Omega}{sub d}> and thus in the dynamic order parameter, Sb, consistent with the bimodal network architecture expected from the synthesis protocol used. Upon addition of less than 10 wt.% m-CB filler, the mean <{Omega}{sub d}> for the longer chains increased by 46% and the width of the distribution increased by 33%. The mean <{Omega}{sub d}> for the shorter chains increased by much less, indicative of preferential dispersion of the filler particles in the long chain domains of the network structure. We conclude that the mechanism of reinforcement is likely a free volume space filling at low loadings transitioning to complex molecular filler and polymer chain interaction phenomena at higher loadings.

  13. Remarks on the maximum correlation coefficient

    OpenAIRE

    Dembo, Amir; Kagan, Abram; Shepp, Lawrence A.

    2001-01-01

    The maximum correlation coefficient between partial sums of independent and identically distributed random variables with finite second moment equals the classical (Pearson) correlation coefficient between the sums, and thus does not depend on the distribution of the random variables. This result is proved, and relations between the linearity of regression of each of two random variables on the other and the maximum correlation coefficient are discussed.

  14. Applying Free Random Variables to Random Matrix Analysis of Financial Data

    CERN Document Server

    Burda, Z; Jurkiewicz, J; Nowak, M A; Papp, G; Zahed, I

    2006-01-01

    We apply the concept of free random variables to correlated Wishart random matrix models. We give a comprehensive rederivation of various spectral densities for a number of financial covariance matrices involving stocks returns without and with exponentially weighted moving averages. We show through simple models how to identify the pertinent underlying correlations. We extend our results to Levy-Wishart random matrix models whereby the risk factors are heavy tailed.

  15. Beyond the random phase approximation

    DEFF Research Database (Denmark)

    Olsen, Thomas; Thygesen, Kristian S.

    2013-01-01

    We assess the performance of a recently proposed renormalized adiabatic local density approximation (rALDA) for ab initio calculations of electronic correlation energies in solids and molecules. The method is an extension of the random phase approximation (RPA) derived from time-dependent density...

  16. Random Conformal Weldings

    CERN Document Server

    Astala, K; Kupiainen, A; Saksman, E

    2009-01-01

    We construct a conformally invariant random family of closed curves in the plane by welding of random homeomorphisms of the unit circle. The homeomorphism is constructed using the exponential of $\\beta X$ where $X$ is the restriction of the two dimensional free field on the circle and the parameter $\\beta$ is in the "high temperature" regime $\\beta<\\sqrt 2$. The welding problem is solved by studying a non-uniformly elliptic Beltrami equation with a random complex dilatation. For the existence a method of Lehto is used. This requires sharp probabilistic estimates to control conformal moduli of annuli and they are proven by decomposing the free field as a sum of independent fixed scale fields and controlling the correlations of the complex dilation restricted to dyadic cells of various scales. For uniqueness we invoke a result by Jones and Smirnov on conformal removability of H\\"older curves. We conjecture that our curves are locally related to SLE$(\\kappa)$ for $\\kappa<4$.

  17. Surrogates with random Fourier Phases

    CERN Document Server

    Raeth, Christoph

    2008-01-01

    The method of surrogates is widely used in the field of nonlinear data analysis for testing for weak nonlinearities. The two most commonly used algorithms for generating surrogates are the amplitude adjusted Fourier transform (AAFT) and the iterated amplitude adjusted Fourier transfom (IAAFT) algorithm. Both the AAFT and IAAFT algorithm conserve the amplitude distribution in real space and reproduce the power spectrum (PS) of the original data set very accurately. The basic assumption in both algorithms is that higher-order correlations can be wiped out using a Fourier phase randomization procedure. In both cases, however, the randomness of the Fourier phases is only imposed before the (first) Fourier back tranformation. Until now, it has not been studied how the subsequent remapping and iteration steps may affect the randomness of the phases. Using the Lorenz system as an example, we show that both algorithms may create surrogate realizations containing Fourier phase correlations. We present two new iterativ...

  18. Cross-correlation laser scattering.

    OpenAIRE

    Kam, Z; Rigler, R

    1982-01-01

    Cross-correlation between two detectors was applied to analyze laser light-scattering fluctuations. Laser scattering from random concentration fluctuations is spatially coherent over small angular areas that are inversely proportional in size to the dimension of the scattering volume. By cross-correlating scattering intensity fluctuations in different angles, the correlation due to relaxation of concentration fluctuations is practically eliminated, and correlations reflecting changes in the s...

  19. Quantifying randomness in real networks

    Science.gov (United States)

    Orsini, Chiara; Dankulov, Marija M.; Colomer-de-Simón, Pol; Jamakovic, Almerima; Mahadevan, Priya; Vahdat, Amin; Bassler, Kevin E.; Toroczkai, Zoltán; Boguñá, Marián; Caldarelli, Guido; Fortunato, Santo; Krioukov, Dmitri

    2015-10-01

    Represented as graphs, real networks are intricate combinations of order and disorder. Fixing some of the structural properties of network models to their values observed in real networks, many other properties appear as statistical consequences of these fixed observables, plus randomness in other respects. Here we employ the dk-series, a complete set of basic characteristics of the network structure, to study the statistical dependencies between different network properties. We consider six real networks--the Internet, US airport network, human protein interactions, technosocial web of trust, English word network, and an fMRI map of the human brain--and find that many important local and global structural properties of these networks are closely reproduced by dk-random graphs whose degree distributions, degree correlations and clustering are as in the corresponding real network. We discuss important conceptual, methodological, and practical implications of this evaluation of network randomness, and release software to generate dk-random graphs.

  20. Effect of random field disorder on the first order transition in p-spin interaction model

    Science.gov (United States)

    Sumedha; Singh, Sushant K.

    2016-01-01

    We study the random field p-spin model with Ising spins on a fully connected graph using the theory of large deviations in this paper. This is a good model to study the effect of quenched random field on systems which have a sharp first order transition in the pure state. For p = 2, the phase-diagram of the model, for bimodal distribution of the random field, has been well studied and is known to undergo a continuous transition for lower values of the random field (h) and a first order transition beyond a threshold, htp(≈ 0.439) . We find the phase diagram of the model, for all p ≥ 2, with bimodal random field distribution, using large deviation techniques. We also look at the fluctuations in the system by calculating the magnetic susceptibility. For p = 2, beyond the tricritical point in the regime of first order transition, we find that for htp ho = 1 / p!), the system does not show ferromagnetic order even at zero temperature. We find that the magnetic susceptibility for p ≥ 3 is discontinuous at the transition point for h