Memory effects on a resonate-and-fire neuron model subjected to Ornstein-Uhlenbeck noise

Science.gov (United States)

Paekivi, S.; Mankin, R.; Rekker, A.

2017-10-01

We consider a generalized Langevin equation with an exponentially decaying memory kernel as a model for the firing process of a resonate-and-fire neuron. The effect of temporally correlated random neuronal input is modeled as Ornstein-Uhlenbeck noise. In the noise-induced spiking regime of the neuron, we derive exact analytical formulas for the dependence of some statistical characteristics of the output spike train, such as the probability distribution of the interspike intervals (ISIs) and the survival probability, on the parameters of the input stimulus. Particularly, on the basis of these exact expressions, we have established sufficient conditions for the occurrence of memory-time-induced transitions between unimodal and multimodal structures of the ISI density and a critical damping coefficient which marks a dynamical transition in the behavior of the system.

Randomness and variability of the neuronal activity described by the Ornstein-Uhlenbeck model

Czech Academy of Sciences Publication Activity Database

Košťál, Lubomír; Lánský, Petr; Zucca, Ch.

2007-01-01

Roč. 18, č. 1 (2007), s. 63-75 ISSN 0954-898X R&D Projects: GA MŠk(CZ) LC554; GA AV ČR(CZ) 1ET400110401; GA AV ČR(CZ) KJB100110701 Grant - others:MIUR(IT) PRIN-Cofin 2005 Institutional research plan: CEZ:AV0Z50110509 Keywords : Ornstein-Uhlenbeck * entropy * randomness Subject RIV: FH - Neurology Impact factor: 1.385, year: 2007

Predicting animal home-range structure and transitions using a multistate Ornstein-Uhlenbeck biased random walk.

Science.gov (United States)

Breed, Greg A; Golson, Emily A; Tinker, M Tim

2017-01-01

The home-range concept is central in animal ecology and behavior, and numerous mechanistic models have been developed to understand home range formation and maintenance. These mechanistic models usually assume a single, contiguous home range. Here we describe and implement a simple home-range model that can accommodate multiple home-range centers, form complex shapes, allow discontinuities in use patterns, and infer how external and internal variables affect movement and use patterns. The model assumes individuals associate with two or more home-range centers and move among them with some estimable probability. Movement in and around home-range centers is governed by a two-dimensional Ornstein-Uhlenbeck process, while transitions between centers are modeled as a stochastic state-switching process. We augmented this base model by introducing environmental and demographic covariates that modify transition probabilities between home-range centers and can be estimated to provide insight into the movement process. We demonstrate the model using telemetry data from sea otters (Enhydra lutris) in California. The model was fit using a Bayesian Markov Chain Monte Carlo method, which estimated transition probabilities, as well as unique Ornstein-Uhlenbeck diffusion and centralizing tendency parameters. Estimated parameters could then be used to simulate movement and space use that was virtually indistinguishable from real data. We used Deviance Information Criterion (DIC) scores to assess model fit and determined that both wind and reproductive status were predictive of transitions between home-range centers. Females were less likely to move between home-range centers on windy days, less likely to move between centers when tending pups, and much more likely to move between centers just after weaning a pup. These tendencies are predicted by theoretical movement rules but were not previously known and show that our model can extract meaningful behavioral insight from complex

Tarificación de bonos sobre catástrofes (cat bonds con desencadenantes de índices de pérdidas. Modelación mediante un proceso de Ornstein-Uhlenbeck || Pricing Loss Index Triggered Cat Bonds. An Ornstein-Uhlenbeck Process-Based Model

Directory of Open Access Journals (Sweden)

Pérez-Fructuoso, María José

2017-12-01

Full Text Available Este artículo propone un modelo aleatorio en tiempo continuo para calcular el índice de pérdidas desencadenante de los bonos sobre catástrofes a partir de la cuantía declarada de siniestros hasta el momento de su vencimiento. Bajo la hipótesis de que la cuantía total de una catástrofe se define como la suma de la cuantía declarada de siniestros y la cuantía de siniestros pendiente de declarar, modelizamos la dinámica lineal decreciente de esta última cuantía mediante un proceso browniano aditivo o proceso de Ornstein-Uhlenbeck. La cuantía declarada de siniestros, entonces, se obtiene por diferencia entre la cuantía total de los siniestros y la cuantía de siniestros pendiente de declarar. Finalmente, se comprueba la validez del modelo propuesto estimando sus parámetros fundamentales y contrastando la bondad del ajuste realizado sobre una muestra de series de datos de seis inundaciones ocurridas en diferentes localidades españolas propensas a sufrir este tipo de catástrofes. || This paper develops a continuous-time random model of loss index triggers for cat bonds on the basis of the loss amount incurred until their maturity. Assuming that total loss amount due to a catastrophe is defined as the sum of the incurred loss amount plus the incurred-but-not-yet reported loss amount, we model the decreasing linear dynamics of the latter amount by means of an additive Brownian process (or Ornstein Uhlenbeck process; and get the former by the difference between the total loss amount and the incurred-but-not-yet-reported loss amount. Finally, we test the validity of the model by estimating its core parameters and by contrasting the goodness of fit through a data series of six floods occurred in several Spanish cities prone to suffer such kind of catastrophes.

Time-changed Ornstein–Uhlenbeck process

International Nuclear Information System (INIS)

Gajda, Janusz; Wyłomańska, Agnieszka

2015-01-01

The Ornstein–Uhlenbeck process is one of the most popular systems used for financial data description. However, this process has also been examined in the context of many other phenomena. In this paper we consider the so-called time-changed Ornstein–Uhlenbeck process, in which time is replaced by an inverse subordinator of general infinite divisible distribution. Time-changed processes nowadays play an important role in various fields of mathematical physics, chemistry, and biology as well as in finance. In this paper we examine the main characteristics of the time-changed Ornstein–Uhlenbeck process, such as the covariance function. Moreover, we also prove the formula for a generalized fractional Fokker–Planck equation that describes the one-dimensional probability density function of the analyzed system. For three cases of subordinators we show the special forms of obtained general formulas. Furthermore, we mention how to simulate the trajectory of the Ornstein–Uhlenbeck process delayed by a general inverse subordinator. (paper)

A cautionary note on the use of Ornstein Uhlenbeck models in macroevolutionary studies.

Science.gov (United States)

Cooper, Natalie; Thomas, Gavin H; Venditti, Chris; Meade, Andrew; Freckleton, Rob P

2016-05-01

Phylogenetic comparative methods are increasingly used to give new insights into the dynamics of trait evolution in deep time. For continuous traits the core of these methods is a suite of models that attempt to capture evolutionary patterns by extending the Brownian constant variance model. However, the properties of these models are often poorly understood, which can lead to the misinterpretation of results. Here we focus on one of these models - the Ornstein Uhlenbeck (OU) model. We show that the OU model is frequently incorrectly favoured over simpler models when using Likelihood ratio tests, and that many studies fitting this model use datasets that are small and prone to this problem. We also show that very small amounts of error in datasets can have profound effects on the inferences derived from OU models. Our results suggest that simulating fitted models and comparing with empirical results is critical when fitting OU and other extensions of the Brownian model. We conclude by making recommendations for best practice in fitting OU models in phylogenetic comparative analyses, and for interpreting the parameters of the OU model.

Diffusion of Brownian particles in a tilted periodic potential under the influence of an external Ornstein-Uhlenbeck noise

Science.gov (United States)

Bai, Zhan-Wu; Zhang, Wei

2018-01-01

The diffusion behaviors of Brownian particles in a tilted periodic potential under the influence of an internal white noise and an external Ornstein-Uhlenbeck noise are investigated through numerical simulation. In contrast to the case when the bias force is smaller or absent, the diffusion coefficient exhibits a nonmonotonic dependence on the correlation time of the external noise when bias force is large. A mechanism different from locked-to-running transition theory is presented for the diffusion enhancement by a bias force in intermediate to large damping. In the underdamped regime and the presence of external noise, the diffusion coefficient is a monotonically decreasing function of low temperature rather than a nonmonotonic function when external noise is absent. The diffusive process undergoes four regimes when bias force approaches but is less than its critical value and noises intensities are small. These behaviors can be attributed to the locked-to-running transition of particles.

The Fractional Ornstein-Uhlenbeck Process

DEFF Research Database (Denmark)

Høg, Esben; Frederiksen, Per H.

The paper revisits dynamic term structure models (DTSMs) and proposes a new way in dealing with the limitation of the classical affine models. In particular, this paper expands the flexibility of the DTSMs by applying a fractional Brownian motion as the governing force of the state variable inste...... of the bond is recovered by solving a fractional version of the fundamental bond pricing equation. Besides this theoretical contribution, the paper proposes an estimation methodology based on the Kalman filter approach, which is applied to the US term structure of interest rates....

Predicting animal home-range structure and transitions using a multistate Ornstein-Uhlenbeck biased random walk

Science.gov (United States)

Breed, Greg A.; Golson, Emily A.; Tinker, M. Tim

2017-01-01

The home‐range concept is central in animal ecology and behavior, and numerous mechanistic models have been developed to understand home range formation and maintenance. These mechanistic models usually assume a single, contiguous home range. Here we describe and implement a simple home‐range model that can accommodate multiple home‐range centers, form complex shapes, allow discontinuities in use patterns, and infer how external and internal variables affect movement and use patterns. The model assumes individuals associate with two or more home‐range centers and move among them with some estimable probability. Movement in and around home‐range centers is governed by a two‐dimensional Ornstein‐Uhlenbeck process, while transitions between centers are modeled as a stochastic state‐switching process. We augmented this base model by introducing environmental and demographic covariates that modify transition probabilities between home‐range centers and can be estimated to provide insight into the movement process. We demonstrate the model using telemetry data from sea otters (Enhydra lutris) in California. The model was fit using a Bayesian Markov Chain Monte Carlo method, which estimated transition probabilities, as well as unique Ornstein‐Uhlenbeck diffusion and centralizing tendency parameters. Estimated parameters could then be used to simulate movement and space use that was virtually indistinguishable from real data. We used Deviance Information Criterion (DIC) scores to assess model fit and determined that both wind and reproductive status were predictive of transitions between home‐range centers. Females were less likely to move between home‐range centers on windy days, less likely to move between centers when tending pups, and much more likely to move between centers just after weaning a pup. These tendencies are predicted by theoretical movement rules but were not previously known and show that our model can extract meaningful

Simple simulation schemes for CIR and Wishart processes

DEFF Research Database (Denmark)

Pisani, Camilla

2013-01-01

We develop some simple simulation algorithms for CIR and Wishart processes. The main idea is the splitting of their generator into the sum of the square of an Ornstein-Uhlenbeck matrix process and a deterministic process. Joint work with Paolo Baldi, Tor Vergata University, Rome...

On the time-homogeneous Ornstein–Uhlenbeck process in the foreign exchange rates

Energy Technology Data Exchange (ETDEWEB)

Fonseca, Regina C.B. da, E-mail: regina@quimica-industrial.com [Department of Mathematics, Instituto Federal de Goiás, Goiânia, Goiás 74055-110 (Brazil); International Center for Condensed Matter Physics, Instituto de Física, Universidade de Brasília, Caixa Postal 04455, 70919-970, Brasília, Distrito Federal (Brazil); Matsushita, Raul Y. [Department of Statistics, Universidade de Brasília, 70919-970, Brasília, Distrito Federal (Brazil); Castro, Márcio T. de; Figueiredo, Annibal [International Center for Condensed Matter Physics, Instituto de Física, Universidade de Brasília, Caixa Postal 04455, 70919-970, Brasília, Distrito Federal (Brazil)

2015-10-02

Since Gaussianity and stationarity assumptions cannot be fulfilled by financial data, the time-homogeneous Ornstein–Uhlenbeck (THOU) process was introduced as a candidate model to describe time series of financial returns [1]. It is an Ornstein–Uhlenbeck (OU) process in which these assumptions are replaced by linearity and time-homogeneity. We employ the OU and THOU processes to analyze daily foreign exchange rates against the US dollar. We confirm that the OU process does not fit the data, while in most cases the first four cumulants patterns from data can be described by the THOU process. However, there are some exceptions in which the data do not follow linearity or time-homogeneity assumptions. - Highlights: • Gaussianity and stationarity assumptions replaced by linearity and time-homogeneity. • We revisit the time-homogeneous Ornstein–Uhlenbeck (THOU) process. • We employ the THOU process to analyze foreign exchange rates against the US dollar. • The first four cumulants patterns from data can be described by the THOU process.

On the time-homogeneous Ornstein–Uhlenbeck process in the foreign exchange rates

International Nuclear Information System (INIS)

Fonseca, Regina C.B. da; Matsushita, Raul Y.; Castro, Márcio T. de; Figueiredo, Annibal

2015-01-01

Since Gaussianity and stationarity assumptions cannot be fulfilled by financial data, the time-homogeneous Ornstein–Uhlenbeck (THOU) process was introduced as a candidate model to describe time series of financial returns [1]. It is an Ornstein–Uhlenbeck (OU) process in which these assumptions are replaced by linearity and time-homogeneity. We employ the OU and THOU processes to analyze daily foreign exchange rates against the US dollar. We confirm that the OU process does not fit the data, while in most cases the first four cumulants patterns from data can be described by the THOU process. However, there are some exceptions in which the data do not follow linearity or time-homogeneity assumptions. - Highlights: • Gaussianity and stationarity assumptions replaced by linearity and time-homogeneity. • We revisit the time-homogeneous Ornstein–Uhlenbeck (THOU) process. • We employ the THOU process to analyze foreign exchange rates against the US dollar. • The first four cumulants patterns from data can be described by the THOU process

Stochastic rocket dynamics under random nozzle side loads: Ornstein-Uhlenbeck boundary layer separation and its coarse grained connection to side loading and rocket response

Energy Technology Data Exchange (ETDEWEB)

Keanini, R.G.; Srivastava, N.; Tkacik, P.T. [Department of Mechanical Engineering, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28078 (United States); Weggel, D.C. [Department of Civil and Environmental Engineering, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28078 (United States); Knight, P.D. [Mitchell Aerospace and Engineering, Statesville, North Carolina 28677 (United States)

2011-06-15

A long-standing, though ill-understood problem in rocket dynamics, rocket response to random, altitude-dependent nozzle side-loads, is investigated. Side loads arise during low altitude flight due to random, asymmetric, shock-induced separation of in-nozzle boundary layers. In this paper, stochastic evolution of the in-nozzle boundary layer separation line, an essential feature underlying side load generation, is connected to random, altitude-dependent rotational and translational rocket response via a set of simple analytical models. Separation line motion, extant on a fast boundary layer time scale, is modeled as an Ornstein-Uhlenbeck process. Pitch and yaw responses, taking place on a long, rocket dynamics time scale, are shown to likewise evolve as OU processes. Stochastic, altitude-dependent rocket translational motion follows from linear, asymptotic versions of the full nonlinear equations of motion; the model is valid in the practical limit where random pitch, yaw, and roll rates all remain small. Computed altitude-dependent rotational and translational velocity and displacement statistics are compared against those obtained using recently reported high fidelity simulations [Srivastava, Tkacik, and Keanini, J. Appl. Phys. 108, 044911 (2010)]; in every case, reasonable agreement is observed. As an important prelude, evidence indicating the physical consistency of the model introduced in the above article is first presented: it is shown that the study's separation line model allows direct derivation of experimentally observed side load amplitude and direction densities. Finally, it is found that the analytical models proposed in this paper allow straightforward identification of practical approaches for: (i) reducing pitch/yaw response to side loads, and (ii) enhancing pitch/yaw damping once side loads cease. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Selected papers on noise and stochastic processes

CERN Document Server

1954-01-01

Six classic papers on stochastic process, selected to meet the needs of physicists, applied mathematicians, and engineers. Contents: 1.Chandrasekhar, S.: Stochastic Problems in Physics and Astronomy. 2. Uhlenbeck, G. E. and Ornstein, L. S.: On the Theory of the Browninan Motion. 3. Ming Chen Wang and Uhlenbeck, G. E.: On the Theory of the Browninan Motion II. 4. Rice, S. O.: Mathematical Analysis of Random Noise. 5. Kac, Mark: Random Walk and the Theory of Brownian Motion. 6. Doob, J. L.: The Brownian Movement and Stochastic Equations. Unabridged republication of the Dover reprint (1954). Pre

Fractional Poincaré inequalities for general measures

KAUST Repository

Mouhot, Clé ment; Russ, Emmanuel; Sire, Yannick

2011-01-01

on the fractional derivative in terms of a weight growing at infinity. The proof goes through the introduction of the generator of the Ornstein-Uhlenbeck semigroup and some careful estimates of its powers. To our knowledge this is the first proof of fractional

Generalized Langevin dynamics of a nanoparticle using a finite element approach: Thermostating with correlated noise

Science.gov (United States)

Uma, B.; Swaminathan, T. N.; Ayyaswamy, P. S.; Eckmann, D. M.; Radhakrishnan, R.

2011-09-01

A direct numerical simulation (DNS) procedure is employed to study the thermal motion of a nanoparticle in an incompressible Newtonian stationary fluid medium with the generalized Langevin approach. We consider both the Markovian (white noise) and non-Markovian (Ornstein-Uhlenbeck noise and Mittag-Leffler noise) processes. Initial locations of the particle are at various distances from the bounding wall to delineate wall effects. At thermal equilibrium, the numerical results are validated by comparing the calculated translational and rotational temperatures of the particle with those obtained from the equipartition theorem. The nature of the hydrodynamic interactions is verified by comparing the velocity autocorrelation functions and mean square displacements with analytical results. Numerical predictions of wall interactions with the particle in terms of mean square displacements are compared with analytical results. In the non-Markovian Langevin approach, an appropriate choice of colored noise is required to satisfy the power-law decay in the velocity autocorrelation function at long times. The results obtained by using non-Markovian Mittag-Leffler noise simultaneously satisfy the equipartition theorem and the long-time behavior of the hydrodynamic correlations for a range of memory correlation times. The Ornstein-Uhlenbeck process does not provide the appropriate hydrodynamic correlations. Comparing our DNS results to the solution of an one-dimensional generalized Langevin equation, it is observed that where the thermostat adheres to the equipartition theorem, the characteristic memory time in the noise is consistent with the inherent time scale of the memory kernel. The performance of the thermostat with respect to equilibrium and dynamic properties for various noise schemes is discussed.

Some continual integrals from gaussian forms

International Nuclear Information System (INIS)

Mazmanishvili, A.S.

1985-01-01

The result summary of continual integration of gaussian functional type is given. The summary contains 124 continual integrals which are the mathematical expectation of the corresponding gaussian form by the continuum of random trajectories of four types: real-valued Ornstein-Uhlenbeck process, Wiener process, complex-valued Ornstein-Uhlenbeck process and the stochastic harmonic one. The summary includes both the known continual integrals and the unpublished before integrals. Mathematical results of the continual integration carried in the work may be applied in the problem of the theory of stochastic process, approaching to the finding of mean from gaussian forms by measures generated by the pointed stochastic processes

The stochastic versus the Euclidean approach to quantum fields on a static space-time

International Nuclear Information System (INIS)

De Angelis, G.F.; de Falco, D.

1986-01-01

Equations are presented which modify the definition of the Gaussian field in the Rindler chart in order to make contact with the Wightman state, the Hartle-Hawking state, and the Euclidean field. By taking Ornstein-Uhlenbeck processes the authors have chosen, in the sense of stochastic mechanics, to place precisely the Fulling modes in their harmonic oscillator ground state. In this respect, together with the periodicity of Minkowski space-time, the authors observe that the covariance of the Ornstein-Uhlenbeck process can be obtained by analytical continuation of the Wightman function of the harmonic oscillator at zero temperature

Mixtures in nonstable Levy processes

International Nuclear Information System (INIS)

Petroni, N Cufaro

2007-01-01

We analyse the Levy processes produced by means of two interconnected classes of nonstable, infinitely divisible distribution: the variance gamma and the Student laws. While the variance gamma family is closed under convolution, the Student one is not: this makes its time evolution more complicated. We prove that-at least for one particular type of Student processes suggested by recent empirical results, and for integral times-the distribution of the process is a mixture of other types of Student distributions, randomized by means of a new probability distribution. The mixture is such that along the time the asymptotic behaviour of the probability density functions always coincide with that of the generating Student law. We put forward the conjecture that this can be a general feature of the Student processes. We finally analyse the Ornstein-Uhlenbeck process driven by our Levy noises and show a few simulations of it

Maximum-entropy description of animal movement.

Science.gov (United States)

Fleming, Chris H; Subaşı, Yiğit; Calabrese, Justin M

2015-03-01

We introduce a class of maximum-entropy states that naturally includes within it all of the major continuous-time stochastic processes that have been applied to animal movement, including Brownian motion, Ornstein-Uhlenbeck motion, integrated Ornstein-Uhlenbeck motion, a recently discovered hybrid of the previous models, and a new model that describes central-place foraging. We are also able to predict a further hierarchy of new models that will emerge as data quality improves to better resolve the underlying continuity of animal movement. Finally, we also show that Langevin equations must obey a fluctuation-dissipation theorem to generate processes that fall from this class of maximum-entropy distributions when the constraints are purely kinematic.

The multivariate supOU stochastic volatility model

DEFF Research Database (Denmark)

Barndorff-Nielsen, Ole; Stelzer, Robert

Using positive semidefinite supOU (superposition of Ornstein-Uhlenbeck type) processes to describe the volatility, we introduce a multivariate stochastic volatility model for financial data which is capable of modelling long range dependence effects. The finiteness of moments and the second order...... structure of the volatility, the log returns, as well as their "squares" are discussed in detail. Moreover, we give several examples in which long memory effects occur and study how the model as well as the simple Ornstein-Uhlenbeck type stochastic volatility model behave under linear transformations....... In particular, the models are shown to be preserved under invertible linear transformations. Finally, we discuss how (sup)OU stochastic volatility models can be combined with a factor modelling approach....

Burgers' turbulence problem with linear or quadratic external potential

DEFF Research Database (Denmark)

Barndorff-Nielsen, Ole Eiler; Leonenko, N.N.

2005-01-01

We consider solutions of Burgers' equation with linear or quadratic external potential and stationary random initial conditions of Ornstein-Uhlenbeck type. We study a class of limit laws that correspond to a scale renormalization of the solutions.......We consider solutions of Burgers' equation with linear or quadratic external potential and stationary random initial conditions of Ornstein-Uhlenbeck type. We study a class of limit laws that correspond to a scale renormalization of the solutions....

Random Young diagrams in a Rectangular Box

DEFF Research Database (Denmark)

Beltoft, Dan; Boutillier, Cédric; Enriquez, Nathanaël

We exhibit the limit shape of random Young diagrams having a distribution proportional to the exponential of their area, and confined in a rectangular box. The Ornstein-Uhlenbeck bridge arises from the fluctuations around the limit shape.......We exhibit the limit shape of random Young diagrams having a distribution proportional to the exponential of their area, and confined in a rectangular box. The Ornstein-Uhlenbeck bridge arises from the fluctuations around the limit shape....

Non-parametric Estimation of Diffusion-Paths Using Wavelet Scaling Methods

DEFF Research Database (Denmark)

Høg, Esben

In continuous time, diffusion processes have been used for modelling financial dynamics for a long time. For example the Ornstein-Uhlenbeck process (the simplest mean-reverting process) has been used to model non-speculative price processes. We discuss non--parametric estimation of these processes...

Non-Parametric Estimation of Diffusion-Paths Using Wavelet Scaling Methods

DEFF Research Database (Denmark)

Høg, Esben

2003-01-01

In continuous time, diffusion processes have been used for modelling financial dynamics for a long time. For example the Ornstein-Uhlenbeck process (the simplest mean--reverting process) has been used to model non-speculative price processes. We discuss non--parametric estimation of these processes...

Rough electricity: a new fractal multi-factor model of electricity spot prices

DEFF Research Database (Denmark)

Bennedsen, Mikkel

We introduce a new mathematical model of electricity spot prices which accounts for the most important stylized facts of these time series: seasonality, spikes, stochastic volatility and mean reversion. Empirical studies have found a possible fifth stylized fact, fractality, and our approach...... explicitly incorporates this into the model of the prices. Our setup generalizes the popular Ornstein Uhlenbeck-based multi-factor framework of Benth et al. (2007) and allows us to perform statistical tests to distinguish between an Ornstein Uhlenbeck-based model and a fractal model. Further, through...... the multi-factor approach we account for seasonality and spikes before estimating - and making inference on - the degree of fractality. This is novel in the literature and we present simulation evidence showing that these precautions are crucial to accurate estimation. Lastly, we estimate our model...

The large deviation principle and steady-state fluctuation theorem for the entropy production rate of a stochastic process in magnetic fields

International Nuclear Information System (INIS)

Chen, Yong; Ge, Hao; Xiong, Jie; Xu, Lihu

2016-01-01

Fluctuation theorem is one of the major achievements in the field of nonequilibrium statistical mechanics during the past two decades. There exist very few results for steady-state fluctuation theorem of sample entropy production rate in terms of large deviation principle for diffusion processes due to the technical difficulties. Here we give a proof for the steady-state fluctuation theorem of a diffusion process in magnetic fields, with explicit expressions of the free energy function and rate function. The proof is based on the Karhunen-Loève expansion of complex-valued Ornstein-Uhlenbeck process.

On the dependence structure of Gaussian queues

NARCIS (Netherlands)

Es-Saghouani, A.; Mandjes, M.R.H.

2009-01-01

In this article we study Gaussian queues (that is, queues fed by Gaussian processes, such as fractional Brownian motion (fBm) and the integrated Ornstein-Uhlenbeck (iOU) process), with a focus on the dependence structure of the workload process. The main question is to what extent does the workload

Reduced equations of motion for quantum systems driven by diffusive Markov processes.

Science.gov (United States)

Sarovar, Mohan; Grace, Matthew D

2012-09-28

The expansion of a stochastic Liouville equation for the coupled evolution of a quantum system and an Ornstein-Uhlenbeck process into a hierarchy of coupled differential equations is a useful technique that simplifies the simulation of stochastically driven quantum systems. We expand the applicability of this technique by completely characterizing the class of diffusive Markov processes for which a useful hierarchy of equations can be derived. The expansion of this technique enables the examination of quantum systems driven by non-Gaussian stochastic processes with bounded range. We present an application of this extended technique by simulating Stark-tuned Förster resonance transfer in Rydberg atoms with nonperturbative position fluctuations.

Multivariate supOU processes

DEFF Research Database (Denmark)

Barndorff-Nielsen, Ole Eiler; Stelzer, Robert

Univariate superpositions of Ornstein-Uhlenbeck (OU) type processes, called supOU processes, provide a class of continuous time processes capable of exhibiting long memory behaviour. This paper introduces multivariate supOU processes and gives conditions for their existence and finiteness...... of moments. Moreover, the second order moment structure is explicitly calculated, and examples exhibit the possibility of long range dependence. Our supOU processes are defined via homogeneous and factorisable Lévy bases. We show that the behaviour of supOU processes is particularly nice when the mean...... reversion parameter is restricted to normal matrices and especially to strictly negative definite ones.For finite variation Lévy bases we are able to give conditions for supOU processes to have locally bounded càdlàg paths of finite variation and to show an analogue of the stochastic differential equation...

Fractional Poincaré inequalities for general measures

KAUST Repository

Mouhot, Clément

2011-01-01

We prove a fractional version of Poincaré inequalities in the context of Rn endowed with a fairly general measure. Namely we prove a control of an L2 norm by a non-local quantity, which plays the role of the gradient in the standard Poincaré inequality. The assumption on the measure is the fact that it satisfies the classical Poincaré inequality, so that our result is an improvement of the latter inequality. Moreover we also quantify the tightness at infinity provided by the control on the fractional derivative in terms of a weight growing at infinity. The proof goes through the introduction of the generator of the Ornstein-Uhlenbeck semigroup and some careful estimates of its powers. To our knowledge this is the first proof of fractional Poincaré inequality for measures more general than Lévy measures. © 2010 Elsevier Masson SAS.

On the inverse transform of Laplace transforms that contain (products of) the parabolic cylinder function

NARCIS (Netherlands)

Veestraeten, D.

2015-01-01

The Laplace transforms of the transition probability density and distribution functions for the Ornstein-Uhlenbeck process contain the product of two parabolic cylinder functions, namely Dv(x)Dv(y) and Dv(x)Dv−1(y), respectively. The inverse transforms of these products have as yet not been

Option pricing under stochastic volatility: the exponential Ornstein–Uhlenbeck model

International Nuclear Information System (INIS)

Perelló, Josep; Masoliver, Jaume; Sircar, Ronnie

2008-01-01

We study the pricing problem for a European call option when the volatility of the underlying asset is random and follows the exponential Ornstein–Uhlenbeck model. The random diffusion model proposed is a two-dimensional market process that takes a log-Brownian motion to describe price dynamics and an Ornstein–Uhlenbeck subordinated process describing the randomness of the log-volatility. We derive an approximate option price that is valid when (i) the fluctuations of the volatility are larger than its normal level, (ii) the volatility presents a slow driving force, toward its normal level and, finally, (iii) the market price of risk is a linear function of the log-volatility. We study the resulting European call price and its implied volatility for a range of parameters consistent with daily Dow Jones index data

The Morris-Lecar neuron model embeds a leaky integrate-and-fire model

DEFF Research Database (Denmark)

Ditlevsen, Susanne; Greenwood, Priscilla

2013-01-01

We showthat the stochastic Morris–Lecar neuron, in a neighborhood of its stable point, can be approximated by a two-dimensional Ornstein Uhlenbeck (OU) modulation of a constant circular motion. The associated radial OU process is an example of a leaky integrate-and-fire (LIF) model prior to firing...

Parameter estimation from observations of first-passage times of the Ornstein-Uhlenbeck process and the Feller process

DEFF Research Database (Denmark)

Ditlevsen, Susanne Dalager; Ditlevsen, Ove Dalager

2008-01-01

a subjective graphical test of the applicability of the OU process or the Feller process when applied to a reasonably large sample of observed first-passage data. These non-stationary processes have several applications in biomedical research, for example as idealized models of the neuron membrane potential...... random time break through to the material surface and become observable. However, the OU process has as a model of physical phenomena the defect of not being bounded to the negative side. This defect is not present for the Feller process, which therefore may provide a useful modeling alternative...

Lyapunov exponent of the random frequency oscillator: cumulant expansion approach

International Nuclear Information System (INIS)

Anteneodo, C; Vallejos, R O

2010-01-01

We consider a one-dimensional harmonic oscillator with a random frequency, focusing on both the standard and the generalized Lyapunov exponents, λ and λ* respectively. We discuss the numerical difficulties that arise in the numerical calculation of λ* in the case of strong intermittency. When the frequency corresponds to a Ornstein-Uhlenbeck process, we compute analytically λ* by using a cumulant expansion including up to the fourth order. Connections with the problem of finding an analytical estimate for the largest Lyapunov exponent of a many-body system with smooth interactions are discussed.

Afrika Statistika ISSN 2316-090X On drift estimation for non-ergodic ...

African Journals Online (AJOL)

Key words: Drift estimation; Discrete observations; Ornstein-Uhlenbeck process; Non- ergodicity. AMS 2010 Mathematics Subject Classification : 60G22; 62M05; 62F12. ∗Corresponding author Khalifa Es-Sebaiy: k.Essebaiy@uca.ma. Djibril Ndiaye : djibykhady@yahoo.fr. 1Supported by ”La commission de l'UEMOA dans le ...

Time-dependent solutions for stochastic systems with delays: Perturbation theory and applications to financial physics

International Nuclear Information System (INIS)

Frank, T.D.

2006-01-01

First-order approximations of time-dependent solutions are determined for stochastic systems perturbed by time-delayed feedback forces. To this end, the theory of delay Fokker-Planck equations is applied in combination with Bayes' theorem. Applications to a time-delayed Ornstein-Uhlenbeck process and the geometric Brownian walk of financial physics are discussed

Maximum likelihood estimation for integrated diffusion processes

DEFF Research Database (Denmark)

Baltazar-Larios, Fernando; Sørensen, Michael

We propose a method for obtaining maximum likelihood estimates of parameters in diffusion models when the data is a discrete time sample of the integral of the process, while no direct observations of the process itself are available. The data are, moreover, assumed to be contaminated...... EM-algorithm to obtain maximum likelihood estimates of the parameters in the diffusion model. As part of the algorithm, we use a recent simple method for approximate simulation of diffusion bridges. In simulation studies for the Ornstein-Uhlenbeck process and the CIR process the proposed method works...... by measurement errors. Integrated volatility is an example of this type of observations. Another example is ice-core data on oxygen isotopes used to investigate paleo-temperatures. The data can be viewed as incomplete observations of a model with a tractable likelihood function. Therefore we propose a simulated...

Neural network connectivity and response latency modelled by stochastic processes

DEFF Research Database (Denmark)

Tamborrino, Massimiliano

is connected to thousands of other neurons. The rst question is: how to model neural networks through stochastic processes? A multivariate Ornstein-Uhlenbeck process, obtained as a diffusion approximation of a jump process, is the proposed answer. Obviously, dependencies between neurons imply dependencies......Stochastic processes and their rst passage times have been widely used to describe the membrane potential dynamics of single neurons and to reproduce neuronal spikes, respectively.However, cerebral cortex in human brains is estimated to contain 10-20 billions of neurons and each of them...... between their spike times. Therefore, the second question is: how to detect neural network connectivity from simultaneously recorded spike trains? Answering this question corresponds to investigate the joint distribution of sequences of rst passage times. A non-parametric method based on copulas...

Random attractors for stochastic lattice reversible Gray-Scott systems with additive noise

Directory of Open Access Journals (Sweden)

Hongyan Li

2015-10-01

Full Text Available In this article, we prove the existence of a random attractor of the stochastic three-component reversible Gray-Scott system on infinite lattice with additive noise. We use a transformation of addition involved with Ornstein-Uhlenbeck process, for proving the pullback absorbing property and the pullback asymptotic compactness of the reaction diffusion system with cubic nonlinearity.

A non-Gaussian Ornstein-Uhlenbeck model for pricing wind power futures

DEFF Research Database (Denmark)

Benth, Fred Espen; Pircalabu, Anca

2018-01-01

generated assuming a recent level of installed capacity. Also, based on one year of observed prices for wind power futures with different delivery periods, we study the market price of risk. Generally, we find a negative risk premium whose magnitude decreases as the length of the delivery period increases....

Sobre uma nova teoria de precificação de opções e outros derivativos

Directory of Open Access Journals (Sweden)

Ailton Cassettari

2001-09-01

Full Text Available Este artigo desenvolve uma nova teoria de precificação de títulos derivativos, implementando-a para a situação particular de opções de compra européias de ações sem dividendos a partir da premissa básica de que o drift do ativo subjacente desempenha papel relevante no processo de precificação, no contexto dos fenômenos de transporte. É feita uma confrontação sistemática com os bem-conhecidos modelos Black-Scholes e Ornstein-Uhlenbeck bivariado que mostra a plausibilidade e efetividade desta abordagem.This paper develops a new theory of derivative securities pricing and implementes it for the specific case of European call options on a hypothetical non-dividend-paying stock. The basic premise is that the drift of the underlying asset plays a very important role in the pricing process, in the context of transport phenomena. A systematic confrontation to well-known Black-Scholes and bivariate trending Ornstein-Uhlenbeck models is also carried out, providing plausibility and effectiveness for this approach.

Estimation of stochastic volatility with long memory for index prices of FTSE Bursa Malaysia KLCI

Energy Technology Data Exchange (ETDEWEB)

Chen, Kho Chia; Kane, Ibrahim Lawal; Rahman, Haliza Abd [Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, 81310, Johor Bahru (Malaysia); Bahar, Arifah [UTM Centre for Industrial and Applied Mathematics (UTM-CIAM), Universiti Teknologi Malaysia, 81310, Johor Bahru and Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, 81310, Johor Bahru (Malaysia); Ting, Chee-Ming [Center for Biomedical Engineering, Universiti Teknologi Malaysia, 81310, Johor Bahru (Malaysia)

2015-02-03

In recent years, modeling in long memory properties or fractionally integrated processes in stochastic volatility has been applied in the financial time series. A time series with structural breaks can generate a strong persistence in the autocorrelation function, which is an observed behaviour of a long memory process. This paper considers the structural break of data in order to determine true long memory time series data. Unlike usual short memory models for log volatility, the fractional Ornstein-Uhlenbeck process is neither a Markovian process nor can it be easily transformed into a Markovian process. This makes the likelihood evaluation and parameter estimation for the long memory stochastic volatility (LMSV) model challenging tasks. The drift and volatility parameters of the fractional Ornstein-Unlenbeck model are estimated separately using the least square estimator (lse) and quadratic generalized variations (qgv) method respectively. Finally, the empirical distribution of unobserved volatility is estimated using the particle filtering with sequential important sampling-resampling (SIR) method. The mean square error (MSE) between the estimated and empirical volatility indicates that the performance of the model towards the index prices of FTSE Bursa Malaysia KLCI is fairly well.

Estimation of stochastic volatility with long memory for index prices of FTSE Bursa Malaysia KLCI

Science.gov (United States)

Chen, Kho Chia; Bahar, Arifah; Kane, Ibrahim Lawal; Ting, Chee-Ming; Rahman, Haliza Abd

2015-02-01

In recent years, modeling in long memory properties or fractionally integrated processes in stochastic volatility has been applied in the financial time series. A time series with structural breaks can generate a strong persistence in the autocorrelation function, which is an observed behaviour of a long memory process. This paper considers the structural break of data in order to determine true long memory time series data. Unlike usual short memory models for log volatility, the fractional Ornstein-Uhlenbeck process is neither a Markovian process nor can it be easily transformed into a Markovian process. This makes the likelihood evaluation and parameter estimation for the long memory stochastic volatility (LMSV) model challenging tasks. The drift and volatility parameters of the fractional Ornstein-Unlenbeck model are estimated separately using the least square estimator (lse) and quadratic generalized variations (qgv) method respectively. Finally, the empirical distribution of unobserved volatility is estimated using the particle filtering with sequential important sampling-resampling (SIR) method. The mean square error (MSE) between the estimated and empirical volatility indicates that the performance of the model towards the index prices of FTSE Bursa Malaysia KLCI is fairly well.

Estimation of stochastic volatility with long memory for index prices of FTSE Bursa Malaysia KLCI

International Nuclear Information System (INIS)

Chen, Kho Chia; Kane, Ibrahim Lawal; Rahman, Haliza Abd; Bahar, Arifah; Ting, Chee-Ming

2015-01-01

In recent years, modeling in long memory properties or fractionally integrated processes in stochastic volatility has been applied in the financial time series. A time series with structural breaks can generate a strong persistence in the autocorrelation function, which is an observed behaviour of a long memory process. This paper considers the structural break of data in order to determine true long memory time series data. Unlike usual short memory models for log volatility, the fractional Ornstein-Uhlenbeck process is neither a Markovian process nor can it be easily transformed into a Markovian process. This makes the likelihood evaluation and parameter estimation for the long memory stochastic volatility (LMSV) model challenging tasks. The drift and volatility parameters of the fractional Ornstein-Unlenbeck model are estimated separately using the least square estimator (lse) and quadratic generalized variations (qgv) method respectively. Finally, the empirical distribution of unobserved volatility is estimated using the particle filtering with sequential important sampling-resampling (SIR) method. The mean square error (MSE) between the estimated and empirical volatility indicates that the performance of the model towards the index prices of FTSE Bursa Malaysia KLCI is fairly well

Optimal consumption problem in the Vasicek model

Directory of Open Access Journals (Sweden)

Jakub Trybuła

2015-01-01

Full Text Available We consider the problem of an optimal consumption strategy on the infinite time horizon based on the hyperbolic absolute risk aversion utility when the interest rate is an Ornstein-Uhlenbeck process. Using the method of subsolution and supersolution we obtain the existence of solutions of the dynamic programming equation. We illustrate the paper with a numerical example of the optimal consumption strategy and the value function.

THE VOLATILITY OF TEMPERATURE AND PRICING OF WEATHER DERIVATIVES

OpenAIRE

Benth, Fred Espen; Saltyte-Benth, Jurate

2005-01-01

We propose an Ornstein-Uhlenbeck process with seasonal volatility to model the time dynamics of daily average temperatures. The model is fitted to almost 43 years of daily observations recorded in Stockholm, one of the European cities for which there is a trade in weather futures and options on the Chicago Mercantile Exchange (CME). Explicit pricing dynamics for futures contracts written on the number of heating/cooling degree-days (so-called HDD/CDD-futures) and the cumulative average daily ...

Hamiltonian formalisms and symmetries of the Pais–Uhlenbeck oscillator

Directory of Open Access Journals (Sweden)

Krzysztof Andrzejewski

2014-12-01

Full Text Available The study of the symmetry of Pais–Uhlenbeck oscillator initiated in Andrzejewski et al. (2014 [24] is continued with special emphasis put on the Hamiltonian formalism. The symmetry generators within the original Pais and Uhlenbeck Hamiltonian approach as well as the canonical transformation to the Ostrogradski Hamiltonian framework are derived. The resulting algebra of generators appears to be the central extension of the one obtained on the Lagrangian level; in particular, in the case of odd frequencies one obtains the centrally extended l-conformal Newton–Hooke algebra. In this important case the canonical transformation to an alternative Hamiltonian formalism (related to the free higher derivatives theory is constructed. It is shown that all generators can be expressed in terms of the ones for the free theory and the result agrees with that obtained by the orbit method.

A General Model for Estimating Macroevolutionary Landscapes.

Science.gov (United States)

Boucher, Florian C; Démery, Vincent; Conti, Elena; Harmon, Luke J; Uyeda, Josef

2018-03-01

The evolution of quantitative characters over long timescales is often studied using stochastic diffusion models. The current toolbox available to students of macroevolution is however limited to two main models: Brownian motion and the Ornstein-Uhlenbeck process, plus some of their extensions. Here, we present a very general model for inferring the dynamics of quantitative characters evolving under both random diffusion and deterministic forces of any possible shape and strength, which can accommodate interesting evolutionary scenarios like directional trends, disruptive selection, or macroevolutionary landscapes with multiple peaks. This model is based on a general partial differential equation widely used in statistical mechanics: the Fokker-Planck equation, also known in population genetics as the Kolmogorov forward equation. We thus call the model FPK, for Fokker-Planck-Kolmogorov. We first explain how this model can be used to describe macroevolutionary landscapes over which quantitative traits evolve and, more importantly, we detail how it can be fitted to empirical data. Using simulations, we show that the model has good behavior both in terms of discrimination from alternative models and in terms of parameter inference. We provide R code to fit the model to empirical data using either maximum-likelihood or Bayesian estimation, and illustrate the use of this code with two empirical examples of body mass evolution in mammals. FPK should greatly expand the set of macroevolutionary scenarios that can be studied since it opens the way to estimating macroevolutionary landscapes of any conceivable shape. [Adaptation; bounds; diffusion; FPK model; macroevolution; maximum-likelihood estimation; MCMC methods; phylogenetic comparative data; selection.].

Towards a unification of the hierarchical reference theory and the self-consistent Ornstein-Zernike approximation.

Science.gov (United States)

Reiner, A; Høye, J S

2005-12-01

The hierarchical reference theory and the self-consistent Ornstein-Zernike approximation are two liquid state theories that both furnish a largely satisfactory description of the critical region as well as phase coexistence and the equation of state in general. Furthermore, there are a number of similarities that suggest the possibility of a unification of both theories. As a first step towards this goal, we consider the problem of combining the lowest order gamma expansion result for the incorporation of a Fourier component of the interaction with the requirement of consistency between internal and free energies, leaving aside the compressibility relation. For simplicity, we restrict ourselves to a simplified lattice gas that is expected to display the same qualitative behavior as more elaborate models. It turns out that the analytically tractable mean spherical approximation is a solution to this problem, as are several of its generalizations. Analysis of the characteristic equations shows the potential for a practical scheme and yields necessary conditions that any closure to the Ornstein-Zernike relation must fulfill for the consistency problem to be well posed and to have a unique differentiable solution. These criteria are expected to remain valid for more general discrete and continuous systems, even if consistency with the compressibility route is also enforced where possible explicit solutions will require numerical evaluations.

Direct simulation Monte Carlo method for the Uehling-Uhlenbeck-Boltzmann equation.

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Garcia, Alejandro L; Wagner, Wolfgang

2003-11-01

In this paper we describe a direct simulation Monte Carlo algorithm for the Uehling-Uhlenbeck-Boltzmann equation in terms of Markov processes. This provides a unifying framework for both the classical Boltzmann case as well as the Fermi-Dirac and Bose-Einstein cases. We establish the foundation of the algorithm by demonstrating its link to the kinetic equation. By numerical experiments we study its sensitivity to the number of simulation particles and to the discretization of the velocity space, when approximating the steady-state distribution.

Amplitudes of solar p modes: Modelling of the eddy time-correlation function

Energy Technology Data Exchange (ETDEWEB)

Belkacem, K [Institut d' Astrophysique et de Geophysique, Universite de Liege, Allee du 6 Aout 17-B 4000 Liege (Belgium); Samadi, R; Goupil, M J, E-mail: Kevin.Belkacem@ulg.ac.BE [LESIA, UMR8109, Universite Pierre et Marie Curie, Universite Denis Diderot, Obs. de Paris, 92195 Meudon Cedex (France)

2011-01-01

Modelling amplitudes of stochastically excited oscillations in stars is a powerful tool for understanding the properties of the convective zones. For instance, it gives us information on the way turbulent eddies are temporally correlated in a very large Reynolds number regime. We discuss the way the time correlation between eddies is modelled and we present recent theoretical developments as well as observational results. Eventually, we discuss the physical underlying meaning of the results by introducing the Ornstein-Uhlenbeck process, which is a sub-class of a Gaussian Markov process.

A feedback control strategy for the airfoil system under non-Gaussian colored noise excitation

Energy Technology Data Exchange (ETDEWEB)

Huang, Yong, E-mail: hy@njust.edu.cn, E-mail: taogang@njust.edu.cn; Tao, Gang, E-mail: hy@njust.edu.cn, E-mail: taogang@njust.edu.cn [School of Energy and Power Engineering, Nanjing University of Science and Technology, 200 XiaoLingwei Street, Nanjing 210094 (China)

2014-09-01

The stability of a binary airfoil with feedback control under stochastic disturbances, a non-Gaussian colored noise, is studied in this paper. First, based on some approximated theories and methods the non-Gaussian colored noise is simplified to an Ornstein-Uhlenbeck process. Furthermore, via the stochastic averaging method and the logarithmic polar transformation, one dimensional diffusion process can be obtained. At last by applying the boundary conditions, the largest Lyapunov exponent which can determine the almost-sure stability of the system and the effective region of control parameters is calculated.

A feedback control strategy for the airfoil system under non-Gaussian colored noise excitation.

Science.gov (United States)

Huang, Yong; Tao, Gang

2014-09-01

The stability of a binary airfoil with feedback control under stochastic disturbances, a non-Gaussian colored noise, is studied in this paper. First, based on some approximated theories and methods the non-Gaussian colored noise is simplified to an Ornstein-Uhlenbeck process. Furthermore, via the stochastic averaging method and the logarithmic polar transformation, one dimensional diffusion process can be obtained. At last by applying the boundary conditions, the largest Lyapunov exponent which can determine the almost-sure stability of the system and the effective region of control parameters is calculated.

On diffusion processes with variable drift rates as models for decision making during learning

International Nuclear Information System (INIS)

Eckhoff, P; Holmes, P; Law, C; Connolly, P M; Gold, J I

2008-01-01

We investigate Ornstein-Uhlenbeck and diffusion processes with variable drift rates as models of evidence accumulation in a visual discrimination task. We derive power-law and exponential drift-rate models and characterize how parameters of these models affect the psychometric function describing performance accuracy as a function of stimulus strength and viewing time. We fit the models to psychophysical data from monkeys learning the task to identify parameters that best capture performance as it improves with training. The most informative parameter was the overall drift rate describing the signal-to-noise ratio of the sensory evidence used to form the decision, which increased steadily with training. In contrast, secondary parameters describing the time course of the drift during motion viewing did not exhibit steady trends. The results indicate that relatively simple versions of the diffusion model can fit behavior over the course of training, thereby giving a quantitative account of learning effects on the underlying decision process

Some classes of multivariate infinitely divisible distributions admitting stochastic integral representations

DEFF Research Database (Denmark)

Barndorff-Nielsen, Ole Eiler; Maejima, M.; Sato, K.

2006-01-01

The class of distributions on R generated by convolutions of Γ-distributions and the class generated by convolutions of mixtures of exponential distributions are generalized to higher dimensions and denoted by T(Rd) and B(Rd) . From the Lévy process {Xt(μ)} on Rd with distribution μ at t=1, Υ...... divisible distributions and of self-decomposable distributions on Rd , respectively. The relations with the mapping Φ from μ to the distribution at each time of the stationary process of Ornstein-Uhlenbeck type with background driving Lévy process {Xt(μ)} are studied. Developments of these results......(μ) is defined as the distribution of the stochastic integral ∫01log(1/t)dXt(μ) . This mapping is a generalization of the mapping Υ introduced by Barndorff-Nielsen and Thorbjørnsen in one dimension. It is proved that ϒ(ID(Rd))=B(Rd) and ϒ(L(Rd))=T(Rd) , where ID(Rd) and L(Rd) are the classes of infinitely...

Equations involving Malliavin calculus operators applications and numerical approximation

CERN Document Server

Levajković, Tijana

2017-01-01

This book provides a comprehensive and unified introduction to stochastic differential equations and related optimal control problems. The material is new and the presentation is reader-friendly. A major contribution of the book is the development of generalized Malliavin calculus in the framework of white noise analysis, based on chaos expansion representation of stochastic processes and its application for solving several classes of stochastic differential equations with singular data involving the main operators of Malliavin calculus. In addition, applications in optimal control and numerical approximations are discussed.  The book is divided into four chapters. The first, entitled White Noise Analysis and Chaos Expansions, includes notation and provides the reader with the theoretical background needed to understand the subsequent chapters.  In Chapter 2, Generalized Operators of Malliavin Calculus, the Malliavin derivative operator, the Skorokhod integral and the Ornstein-Uhlenbeck operator are introdu...

Fractional Number Operator and Associated Fractional Diffusion Equations

Science.gov (United States)

Rguigui, Hafedh

2018-03-01

In this paper, we study the fractional number operator as an analog of the finite-dimensional fractional Laplacian. An important relation with the Ornstein-Uhlenbeck process is given. Using a semigroup approach, the solution of the Cauchy problem associated to the fractional number operator is presented. By means of the Mittag-Leffler function and the Laplace transform, we give the solution of the Caputo time fractional diffusion equation and Riemann-Liouville time fractional diffusion equation in infinite dimensions associated to the fractional number operator.

The simulation of the non-Markovian behaviour of a two-level system

Science.gov (United States)

Semina, I.; Petruccione, F.

2016-05-01

Non-Markovian relaxation dynamics of a two-level system is studied with the help of the non-linear stochastic Schrödinger equation with coloured Ornstein-Uhlenbeck noise. This stochastic Schrödinger equation is investigated numerically with an adapted Platen scheme. It is shown, that the memory effects have a significant impact to the dynamics of the system.

Only through perturbation can relaxation times be estimated

DEFF Research Database (Denmark)

Ditlevsen, Susanne; Lansky, Petr

2012-01-01

Estimation of model parameters is as important as model building, but is often neglected in model studies. Here we show that despite the existence of well known results on parameter estimation in a simple homogenous Ornstein-Uhlenbeck process, in most practical situations the methods suffer greatly...... on computer experiments based on applications in neuroscience and pharmacokinetics, which show a striking improvement of the quality of estimation. The results are important for judicious designs of experiments to obtain maximal information from each data point, especially when samples are expensive...

Predictive performance for population models using stochastic differential equations applied on data from an oral glucose tolerance test.

Science.gov (United States)

Møller, Jonas B; Overgaard, Rune V; Madsen, Henrik; Hansen, Torben; Pedersen, Oluf; Ingwersen, Steen H

2010-02-01

Several articles have investigated stochastic differential equations (SDEs) in PK/PD models, but few have quantitatively investigated the benefits to predictive performance of models based on real data. Estimation of first phase insulin secretion which reflects beta-cell function using models of the OGTT is a difficult problem in need of further investigation. The present work aimed at investigating the power of SDEs to predict the first phase insulin secretion (AIR (0-8)) in the IVGTT based on parameters obtained from the minimal model of the OGTT, published by Breda et al. (Diabetes 50(1):150-158, 2001). In total 174 subjects underwent both an OGTT and a tolbutamide modified IVGTT. Estimation of parameters in the oral minimal model (OMM) was performed using the FOCE-method in NONMEM VI on insulin and C-peptide measurements. The suggested SDE models were based on a continuous AR(1) process, i.e. the Ornstein-Uhlenbeck process, and the extended Kalman filter was implemented in order to estimate the parameters of the models. Inclusion of the Ornstein-Uhlenbeck (OU) process caused improved description of the variation in the data as measured by the autocorrelation function (ACF) of one-step prediction errors. A main result was that application of SDE models improved the correlation between the individual first phase indexes obtained from OGTT and AIR (0-8) (r = 0.36 to r = 0.49 and r = 0.32 to r = 0.47 with C-peptide and insulin measurements, respectively). In addition to the increased correlation also the properties of the indexes obtained using the SDE models more correctly assessed the properties of the first phase indexes obtained from the IVGTT. In general it is concluded that the presented SDE approach not only caused autocorrelation of errors to decrease but also improved estimation of clinical measures obtained from the glucose tolerance tests. Since, the estimation time of extended models was not heavily increased compared to basic models, the applied method

Entropy Production and Fluctuation Theorems for Active Matter

Science.gov (United States)

Mandal, Dibyendu; Klymko, Katherine; DeWeese, Michael R.

2017-12-01

Active biological systems reside far from equilibrium, dissipating heat even in their steady state, thus requiring an extension of conventional equilibrium thermodynamics and statistical mechanics. In this Letter, we have extended the emerging framework of stochastic thermodynamics to active matter. In particular, for the active Ornstein-Uhlenbeck model, we have provided consistent definitions of thermodynamic quantities such as work, energy, heat, entropy, and entropy production at the level of single, stochastic trajectories and derived related fluctuation relations. We have developed a generalization of the Clausius inequality, which is valid even in the presence of the non-Hamiltonian dynamics underlying active matter systems. We have illustrated our results with explicit numerical studies.

Analyses of (0.5part>)-1dNch/dη distributions of PHOBOS and BRAHMS collaborations by means of a stochastic process

International Nuclear Information System (INIS)

Biyajima, M.; Ide, M.; Mizoguchi, T.; Suzuki, N.

2002-01-01

Recently interesting data on dN ch /dη in Au-Au collisions (η=-ln tan(θ/2)) with the centrality cuts have been reported by PHOBOS and BRAHMS Collaborations. Their data are usually divided by the number of participants (nucleons) in collisions. Instead of this way, using the total multiplicity N ch =∫(dN ch /dη)dη, we find that there are scaling phenomena among (N ch ) -1 dN ch /dη=dn/dη with different centrality cuts at √s NN = 130 GeV and 200 GeV, respectively. To explain these scaling behaviors of dn/dη, we consider the stochastic approach named Ornstein-Uhlenbeck process with two sources. The Langevin equation is adopted for the present explanation. Among dn/dη at 130 GeV and 200 GeV, no significant difference has been found. Possible detection method of the quark-gluon plasma (QGP) through dN ch /dη is presented. (author)

Directed transport of confined Brownian particles with torque

Science.gov (United States)

Radtke, Paul K.; Schimansky-Geier, Lutz

2012-05-01

We investigate the influence of an additional torque on the motion of Brownian particles confined in a channel geometry with varying width. The particles are driven by random fluctuations modeled by an Ornstein-Uhlenbeck process with given correlation time τc. The latter causes persistent motion and is implemented as (i) thermal noise in equilibrium and (ii) noisy propulsion in nonequilibrium. In the nonthermal process a directed transport emerges; its properties are studied in detail with respect to the correlation time, the torque, and the channel geometry. Eventually, the transport mechanism is traced back to a persistent sliding of particles along the even boundaries in contrast to scattered motion at uneven or rough ones.

Level crossings and excess times due to a superposition of uncorrelated exponential pulses

Science.gov (United States)

Theodorsen, A.; Garcia, O. E.

2018-01-01

A well-known stochastic model for intermittent fluctuations in physical systems is investigated. The model is given by a superposition of uncorrelated exponential pulses, and the degree of pulse overlap is interpreted as an intermittency parameter. Expressions for excess time statistics, that is, the rate of level crossings above a given threshold and the average time spent above the threshold, are derived from the joint distribution of the process and its derivative. Limits of both high and low intermittency are investigated and compared to previously known results. In the case of a strongly intermittent process, the distribution of times spent above threshold is obtained analytically. This expression is verified numerically, and the distribution of times above threshold is explored for other intermittency regimes. The numerical simulations compare favorably to known results for the distribution of times above the mean threshold for an Ornstein-Uhlenbeck process. This contribution generalizes the excess time statistics for the stochastic model, which find applications in a wide diversity of natural and technological systems.

Effective equilibrium states in the colored-noise model for active matter I. Pairwise forces in the Fox and unified colored noise approximations

Science.gov (United States)

Wittmann, René; Maggi, C.; Sharma, A.; Scacchi, A.; Brader, J. M.; Marini Bettolo Marconi, U.

2017-11-01

The equations of motion of active systems can be modeled in terms of Ornstein-Uhlenbeck processes (OUPs) with appropriate correlators. For further theoretical studies, these should be approximated to yield a Markovian picture for the dynamics and a simplified steady-state condition. We perform a comparative study of the unified colored noise approximation (UCNA) and the approximation scheme by Fox recently employed within this context. We review the approximations necessary to define effective interaction potentials in the low-density limit and study the conditions for which these represent the behavior observed in two-body simulations for the OUPs model and active Brownian particles. The demonstrated limitations of the theory for potentials with a negative slope or curvature can be qualitatively corrected by a new empirical modification. In general, we find that in the presence of translational white noise the Fox approach is more accurate. Finally, we examine an alternative way to define a force-balance condition in the limit of small activity.

Trait-specific processes of convergence and conservatism shape ecomorphological evolution in ground-dwelling squirrels.

Science.gov (United States)

McLean, Bryan S; Helgen, Kristofer M; Goodwin, H Thomas; Cook, Joseph A

2018-03-01

Our understanding of mechanisms operating over deep timescales to shape phenotypic diversity often hinges on linking variation in one or few trait(s) to specific evolutionary processes. When distinct processes are capable of similar phenotypic signatures, however, identifying these drivers is difficult. We explored ecomorphological evolution across a radiation of ground-dwelling squirrels whose history includes convergence and constraint, two processes that can yield similar signatures of standing phenotypic diversity. Using four ecologically relevant trait datasets (body size, cranial, mandibular, and molariform tooth shape), we compared and contrasted variation, covariation, and disparity patterns in a new phylogenetic framework. Strong correlations existed between body size and two skull traits (allometry) and among skull traits themselves (integration). Inferred evolutionary modes were also concordant across traits (Ornstein-Uhlenbeck with two adaptive regimes). However, despite these broad similarities, we found divergent dynamics on the macroevolutionary landscape, with phenotypic disparity being differentially shaped by convergence and conservatism. Such among-trait heterogeneity in process (but not always pattern) reiterates the mosaic nature of morphological evolution, and suggests ground squirrel evolution is poorly captured by single process descriptors. Our results also highlight how use of single traits can bias macroevolutionary inference, affirming the importance of broader trait-bases in understanding phenotypic evolutionary dynamics. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Fast shuttling of a particle under weak spring-constant noise of the moving trap

Science.gov (United States)

Lu, Xiao-Jing; Ruschhaupt, A.; Muga, J. G.

2018-05-01

We investigate the excitation of a quantum particle shuttled in a harmonic trap with weak spring-constant colored noise. The Ornstein-Uhlenbeck model for the noise correlation function describes a wide range of possible noises, in particular for short correlation times the white-noise limit examined by Lu et al. [Phys. Rev. A 89, 063414 (2014)], 10.1103/PhysRevA.89.063414 and, by averaging over correlation times, "1 /f flicker noise." We find expressions for the excitation energy in terms of static (independent of trap motion) and dynamical sensitivities, with opposite behavior with respect to shuttling time, and demonstrate that the excitation can be reduced by proper process timing and design of the trap trajectory.

Digital hardware implementation of a stochastic two-dimensional neuron model.

Science.gov (United States)

Grassia, F; Kohno, T; Levi, T

2016-11-01

This study explores the feasibility of stochastic neuron simulation in digital systems (FPGA), which realizes an implementation of a two-dimensional neuron model. The stochasticity is added by a source of current noise in the silicon neuron using an Ornstein-Uhlenbeck process. This approach uses digital computation to emulate individual neuron behavior using fixed point arithmetic operation. The neuron model's computations are performed in arithmetic pipelines. It was designed in VHDL language and simulated prior to mapping in the FPGA. The experimental results confirmed the validity of the developed stochastic FPGA implementation, which makes the implementation of the silicon neuron more biologically plausible for future hybrid experiments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tempo and mode of performance evolution across multiple independent origins of adhesive toe pads in lizards.

Science.gov (United States)

Hagey, Travis J; Uyeda, Josef C; Crandell, Kristen E; Cheney, Jorn A; Autumn, Kellar; Harmon, Luke J

2017-10-01

Understanding macroevolutionary dynamics of trait evolution is an important endeavor in evolutionary biology. Ecological opportunity can liberate a trait as it diversifies through trait space, while genetic and selective constraints can limit diversification. While many studies have examined the dynamics of morphological traits, diverse morphological traits may yield the same or similar performance and as performance is often more proximately the target of selection, examining only morphology may give an incomplete understanding of evolutionary dynamics. Here, we ask whether convergent evolution of pad-bearing lizards has followed similar evolutionary dynamics, or whether independent origins are accompanied by unique constraints and selective pressures over macroevolutionary time. We hypothesized that geckos and anoles each have unique evolutionary tempos and modes. Using performance data from 59 species, we modified Brownian motion (BM) and Ornstein-Uhlenbeck (OU) models to account for repeated origins estimated using Bayesian ancestral state reconstructions. We discovered that adhesive performance in geckos evolved in a fashion consistent with Brownian motion with a trend, whereas anoles evolved in bounded performance space consistent with more constrained evolution (an Ornstein-Uhlenbeck model). Our results suggest that convergent phenotypes can have quite distinctive evolutionary patterns, likely as a result of idiosyncratic constraints or ecological opportunities. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Distribution of return point memory states for systems with stochastic inputs

International Nuclear Information System (INIS)

Amann, A; Brokate, M; Rachinskii, D; Temnov, G

2011-01-01

We consider the long term effect of stochastic inputs on the state of an open loop system which exhibits the so-called return point memory. An example of such a system is the Preisach model; more generally, systems with the Preisach type input-state relationship, such as in spin-interaction models, are considered. We focus on the characterisation of the expected memory configuration after the system has been effected by the input for sufficiently long period of time. In the case where the input is given by a discrete time random walk process, or the Wiener process, simple closed form expressions for the probability density of the vector of the main input extrema recorded by the memory state, and scaling laws for the dimension of this vector, are derived. If the input is given by a general continuous Markov process, we show that the distribution of previous memory elements can be obtained from a Markov chain scheme which is derived from the solution of an associated one-dimensional escape type problem. Formulas for transition probabilities defining this Markov chain scheme are presented. Moreover, explicit formulas for the conditional probability densities of previous main extrema are obtained for the Ornstein-Uhlenbeck input process. The analytical results are confirmed by numerical experiments.

Weak convergence of marked point processes generated by crossings of multivariate jump processes

DEFF Research Database (Denmark)

Tamborrino, Massimiliano; Sacerdote, Laura; Jacobsen, Martin

2014-01-01

We consider the multivariate point process determined by the crossing times of the components of a multivariate jump process through a multivariate boundary, assuming to reset each component to an initial value after its boundary crossing. We prove that this point process converges weakly...... process converging to a multivariate Ornstein–Uhlenbeck process is discussed as a guideline for applying diffusion limits for jump processes. We apply our theoretical findings to neural network modeling. The proposed model gives a mathematical foundation to the generalization of the class of Leaky...

Intensity-interferometric test of nuclear collision geometries obtained from the Boltzmann-Uehling-Uhlenbeck equation

International Nuclear Information System (INIS)

Gong, W.G.; Bauer, W.; Gelbke, C.K.; Carlin, N.; de Souza, R.T.; Kim, Y.D.; Lynch, W.G.; Murakami, T.; Poggi, G.; Sanderson, D.P.; Tsang, M.B.; Xu, H.M.; Pratt, S.; Fields, D.E.; Kwiatkowski, K.; Planeta, R.; Viola, V.E. Jr.; Yennello, S.J.

1990-01-01

Two-proton correlation functions measured for the 14 N+ 27 Al reaction at E/A=75 MeV are compared to correlation functions predicted for collision geometries obtained from numerical solutions of the Boltzmann-Uehling-Uhlenbeck (BUU) equation. The calculations are in rather good agreement with the experimental correlation function, indicating that the BUU equation gives a reasonable description of the space-time evolution of the reaction

Application of the Ornstein-Zernike formalism to polymer and copolymer blends

International Nuclear Information System (INIS)

Benmouna, M.

1988-09-01

The Ornstein Zernike formalism is shown to be applicable to polymer and copolymer blends. Direct correlation functions are obtained from the solution problem by using a simple procedure which was suggested before (M. Benmouna, H. Benoit and W. Wu, to be published in Macromolecules). This procedure consists essentially of replacing the volume fraction of solvent by the quantity φ c N c P c (q) where φ c , N c and P c (q) are the volume fraction, the degree of polymerization and the form factor as a function of momentum transfer q, respectively. (author). 9 refs

Modeling sheep pox disease from the 1994-1998 epidemic in Evros Prefecture, Greece.

Science.gov (United States)

Malesios, C; Demiris, N; Abas, Z; Dadousis, K; Koutroumanidis, T

2014-10-01

Sheep pox is a highly transmissible disease which can cause serious loss of livestock and can therefore have major economic impact. We present data from sheep pox epidemics which occurred between 1994 and 1998. The data include weekly records of infected farms as well as a number of covariates. We implement Bayesian stochastic regression models which, in addition to various explanatory variables like seasonal and environmental/meteorological factors, also contain serial correlation structure based on variants of the Ornstein-Uhlenbeck process. We take a predictive view in model selection by utilizing deviance-based measures. The results indicate that seasonality and the number of infected farms are important predictors for sheep pox incidence. Copyright © 2014 Elsevier Ltd. All rights reserved.

Modeling and Forecasting Average Temperature for Weather Derivative Pricing

Directory of Open Access Journals (Sweden)

Zhiliang Wang

2015-01-01

Full Text Available The main purpose of this paper is to present a feasible model for the daily average temperature on the area of Zhengzhou and apply it to weather derivatives pricing. We start by exploring the background of weather derivatives market and then use the 62 years of daily historical data to apply the mean-reverting Ornstein-Uhlenbeck process to describe the evolution of the temperature. Finally, Monte Carlo simulations are used to price heating degree day (HDD call option for this city, and the slow convergence of the price of the HDD call can be found through taking 100,000 simulations. The methods of the research will provide a frame work for modeling temperature and pricing weather derivatives in other similar places in China.

What defines an adaptive radiation? Macroevolutionary diversification dynamics of an exceptionally species-rich continental lizard radiation.

Science.gov (United States)

Pincheira-Donoso, Daniel; Harvey, Lilly P; Ruta, Marcello

2015-08-07

radiations in continents, but may emerge less frequently (compared to islands) when major events (e.g., climatic, geographic) significantly modify environments. In contrast, body size diversification conforms to an Ornstein-Uhlenbeck model with multiple trait optima. Despite this asymmetric diversification between both lineages and phenotype, links are expected to exist between the two processes, as shown by our trait-dependent analyses of diversification. We finally suggest that the definition of adaptive radiation should not be conditioned by the existence of early-bursts of diversification, and should instead be generalized to lineages in which species and ecological diversity have evolved from a single ancestor.

Potential and flux field landscape theory. II. Non-equilibrium thermodynamics of spatially inhomogeneous stochastic dynamical systems

International Nuclear Information System (INIS)

Wu, Wei; Wang, Jin

2014-01-01

We have established a general non-equilibrium thermodynamic formalism consistently applicable to both spatially homogeneous and, more importantly, spatially inhomogeneous systems, governed by the Langevin and Fokker-Planck stochastic dynamics with multiple state transition mechanisms, using the potential-flux landscape framework as a bridge connecting stochastic dynamics with non-equilibrium thermodynamics. A set of non-equilibrium thermodynamic equations, quantifying the relations of the non-equilibrium entropy, entropy flow, entropy production, and other thermodynamic quantities, together with their specific expressions, is constructed from a set of dynamical decomposition equations associated with the potential-flux landscape framework. The flux velocity plays a pivotal role on both the dynamic and thermodynamic levels. On the dynamic level, it represents a dynamic force breaking detailed balance, entailing the dynamical decomposition equations. On the thermodynamic level, it represents a thermodynamic force generating entropy production, manifested in the non-equilibrium thermodynamic equations. The Ornstein-Uhlenbeck process and more specific examples, the spatial stochastic neuronal model, in particular, are studied to test and illustrate the general theory. This theoretical framework is particularly suitable to study the non-equilibrium (thermo)dynamics of spatially inhomogeneous systems abundant in nature. This paper is the second of a series

Euler and Navier endash Stokes limits of the Uehling endash Uhlenbeck quantum kinetic equations

International Nuclear Information System (INIS)

Arlotti, L.; Lachowicz, M.

1997-01-01

The Uehling endash Uhlenbeck evolution equations for gases of identical quantum particles either fermions or bosons, in the case in which the collision kernel does not depend on the distribution function, are considered. The existence of solutions and their asymptotic relations with solutions of the hydrodynamic equations both at the level of the Euler system and at the level of the Navier endash Stokes system are proved. copyright 1997 American Institute of Physics

Analytical free energy gradient for the molecular Ornstein-Zernike self-consistent-field method

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N.Yoshida

2007-09-01

Full Text Available An analytical free energy gradient for the molecular Ornstein-Zernike self-consistent-field (MOZ-SCF method is presented. MOZ-SCF theory is one of the theories to considering the solvent effects on the solute electronic structure in solution. [Yoshida N. et al., J. Chem. Phys., 2000, 113, 4974] Molecular geometries of water, formaldehyde, acetonitrile and acetone in water are optimized by analytical energy gradient formula. The results are compared with those from the polarizable continuum model (PCM, the reference interaction site model (RISM-SCF and the three dimensional (3D RISM-SCF.

Value of the future: Discounting in random environments

Science.gov (United States)

Farmer, J. Doyne; Geanakoplos, John; Masoliver, Jaume; Montero, Miquel; Perelló, Josep

2015-05-01

We analyze how to value future costs and benefits when they must be discounted relative to the present. We introduce the subject for the nonspecialist and take into account the randomness of the economic evolution by studying the discount function of three widely used processes for the dynamics of interest rates: Ornstein-Uhlenbeck, Feller, and log-normal. Besides obtaining exact expressions for the discount function and simple asymptotic approximations, we show that historical average interest rates overestimate long-run discount rates and that this effect can be large. In other words, long-run discount rates should be substantially less than the average rate observed in the past, otherwise any cost-benefit calculation would be biased in favor of the present and against interventions that may protect the future.

Moment Lyapunov Exponent and Stochastic Stability of Binary Airfoil under Combined Harmonic and Non-Gaussian Colored Noise Excitations

Science.gov (United States)

Hu, D. L.; Liu, X. B.

Both periodic loading and random forces commonly co-exist in real engineering applications. However, the dynamic behavior, especially dynamic stability of systems under parametric periodic and random excitations has been reported little in the literature. In this study, the moment Lyapunov exponent and stochastic stability of binary airfoil under combined harmonic and non-Gaussian colored noise excitations are investigated. The noise is simplified to an Ornstein-Uhlenbeck process by applying the path-integral method. Via the singular perturbation method, the second-order expansions of the moment Lyapunov exponent are obtained, which agree well with the results obtained by the Monte Carlo simulation. Finally, the effects of the noise and parametric resonance (such as subharmonic resonance and combination additive resonance) on the stochastic stability of the binary airfoil system are discussed.

Coupling regularizes individual units in noisy populations

International Nuclear Information System (INIS)

Ly Cheng; Ermentrout, G. Bard

2010-01-01

The regularity of a noisy system can modulate in various ways. It is well known that coupling in a population can lower the variability of the entire network; the collective activity is more regular. Here, we show that diffusive (reciprocal) coupling of two simple Ornstein-Uhlenbeck (O-U) processes can regularize the individual, even when it is coupled to a noisier process. In cellular networks, the regularity of individual cells is important when a select few play a significant role. The regularizing effect of coupling surprisingly applies also to general nonlinear noisy oscillators. However, unlike with the O-U process, coupling-induced regularity is robust to different kinds of coupling. With two coupled noisy oscillators, we derive an asymptotic formula assuming weak noise and coupling for the variance of the period (i.e., spike times) that accurately captures this effect. Moreover, we find that reciprocal coupling can regularize the individual period of higher dimensional oscillators such as the Morris-Lecar and Brusselator models, even when coupled to noisier oscillators. Coupling can have a counterintuitive and beneficial effect on noisy systems. These results have implications for the role of connectivity with noisy oscillators and the modulation of variability of individual oscillators.

HMM filtering and parameter estimation of an electricity spot price model

International Nuclear Information System (INIS)

Erlwein, Christina; Benth, Fred Espen; Mamon, Rogemar

2010-01-01

In this paper we develop a model for electricity spot price dynamics. The spot price is assumed to follow an exponential Ornstein-Uhlenbeck (OU) process with an added compound Poisson process. In this way, the model allows for mean-reversion and possible jumps. All parameters are modulated by a hidden Markov chain in discrete time. They are able to switch between different economic regimes representing the interaction of various factors. Through the application of reference probability technique, adaptive filters are derived, which in turn, provide optimal estimates for the state of the Markov chain and related quantities of the observation process. The EM algorithm is applied to find optimal estimates of the model parameters in terms of the recursive filters. We implement this self-calibrating model on a deseasonalised series of daily spot electricity prices from the Nordic exchange Nord Pool. On the basis of one-step ahead forecasts, we found that the model is able to capture the empirical characteristics of Nord Pool spot prices. (author)

Self-consistent relativistic Boltzmann-Uehling-Uhlenbeck equation for the Δ distribution function

International Nuclear Information System (INIS)

Mao, G.; Li, Z.; Zhuo, Y.

1996-01-01

We derive the self-consistent relativistic Boltzmann-Uehling-Uhlenbeck (RBUU) equation for the delta distribution function within the framework which we have done for nucleon close-quote s. In our approach, the Δ isobars are treated in essentially the same way as nucleons. Both mean field and collision terms of Δ close-quote s RBUU equation are derived from the same effective Lagrangian and presented analytically. We calculate the in-medium NΔ elastic and inelastic scattering cross sections up to twice nuclear matter density and the results show that the in-medium cross sections deviate substantially from Cugnon close-quote s parametrization that is commonly used in the transport model. copyright 1996 The American Physical Society

The Uhlenbeck-Ford model: Exact virial coefficients and application as a reference system in fluid-phase free-energy calculations

Science.gov (United States)

Paula Leite, Rodolfo; Freitas, Rodrigo; Azevedo, Rodolfo; de Koning, Maurice

2016-11-01

The Uhlenbeck-Ford (UF) model was originally proposed for the theoretical study of imperfect gases, given that all its virial coefficients can be evaluated exactly, in principle. Here, in addition to computing the previously unknown coefficients B11 through B13, we assess its applicability as a reference system in fluid-phase free-energy calculations using molecular simulation techniques. Our results demonstrate that, although the UF model itself is too soft, appropriately scaled Uhlenbeck-Ford (sUF) models provide robust reference systems that allow accurate fluid-phase free-energy calculations without the need for an intermediate reference model. Indeed, in addition to the accuracy with which their free energies are known and their convenient scaling properties, the fluid is the only thermodynamically stable phase for a wide range of sUF models. This set of favorable properties may potentially put the sUF fluid-phase reference systems on par with the standard role that harmonic and Einstein solids play as reference systems for solid-phase free-energy calculations.

Green's function-stochastic methods framework for probing nonlinear evolution problems: Burger's equation, the nonlinear Schroedinger's equation, and hydrodynamic organization of near-molecular-scale vorticity

International Nuclear Information System (INIS)

Keanini, R.G.

2011-01-01

Research highlights: → Systematic approach for physically probing nonlinear and random evolution problems. → Evolution of vortex sheets corresponds to evolution of an Ornstein-Uhlenbeck process. → Organization of near-molecular scale vorticity mediated by hydrodynamic modes. → Framework allows calculation of vorticity evolution within random strain fields. - Abstract: A framework which combines Green's function (GF) methods and techniques from the theory of stochastic processes is proposed for tackling nonlinear evolution problems. The framework, established by a series of easy-to-derive equivalences between Green's function and stochastic representative solutions of linear drift-diffusion problems, provides a flexible structure within which nonlinear evolution problems can be analyzed and physically probed. As a preliminary test bed, two canonical, nonlinear evolution problems - Burgers' equation and the nonlinear Schroedinger's equation - are first treated. In the first case, the framework provides a rigorous, probabilistic derivation of the well known Cole-Hopf ansatz. Likewise, in the second, the machinery allows systematic recovery of a known soliton solution. The framework is then applied to a fairly extensive exploration of physical features underlying evolution of randomly stretched and advected Burger's vortex sheets. Here, the governing vorticity equation corresponds to the Fokker-Planck equation of an Ornstein-Uhlenbeck process, a correspondence that motivates an investigation of sub-sheet vorticity evolution and organization. Under the assumption that weak hydrodynamic fluctuations organize disordered, near-molecular-scale, sub-sheet vorticity, it is shown that these modes consist of two weakly damped counter-propagating cross-sheet acoustic modes, a diffusive cross-sheet shear mode, and a diffusive cross-sheet entropy mode. Once a consistent picture of in-sheet vorticity evolution is established, a number of analytical results, describing the

The development of a revised version of multi-center molecular Ornstein-Zernike equation

Science.gov (United States)

Kido, Kentaro; Yokogawa, Daisuke; Sato, Hirofumi

2012-04-01

Ornstein-Zernike (OZ)-type theory is a powerful tool to obtain 3-dimensional solvent distribution around solute molecule. Recently, we proposed multi-center molecular OZ method, which is suitable for parallel computing of 3D solvation structure. The distribution function in this method consists of two components, namely reference and residue parts. Several types of the function were examined as the reference part to investigate the numerical robustness of the method. As the benchmark, the method is applied to water, benzene in aqueous solution and single-walled carbon nanotube in chloroform solution. The results indicate that fully-parallelization is achieved by utilizing the newly proposed reference functions.

The best of both worlds: Phylogenetic eigenvector regression and mapping

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José Alexandre Felizola Diniz Filho

2015-09-01

Full Text Available Eigenfunction analyses have been widely used to model patterns of autocorrelation in time, space and phylogeny. In a phylogenetic context, Diniz-Filho et al. (1998 proposed what they called Phylogenetic Eigenvector Regression (PVR, in which pairwise phylogenetic distances among species are submitted to a Principal Coordinate Analysis, and eigenvectors are then used as explanatory variables in regression, correlation or ANOVAs. More recently, a new approach called Phylogenetic Eigenvector Mapping (PEM was proposed, with the main advantage of explicitly incorporating a model-based warping in phylogenetic distance in which an Ornstein-Uhlenbeck (O-U process is fitted to data before eigenvector extraction. Here we compared PVR and PEM in respect to estimated phylogenetic signal, correlated evolution under alternative evolutionary models and phylogenetic imputation, using simulated data. Despite similarity between the two approaches, PEM has a slightly higher prediction ability and is more general than the original PVR. Even so, in a conceptual sense, PEM may provide a technique in the best of both worlds, combining the flexibility of data-driven and empirical eigenfunction analyses and the sounding insights provided by evolutionary models well known in comparative analyses.

Estimation of mean-reverting oil prices: a laboratory approach

International Nuclear Information System (INIS)

Bjerksund, P.; Stensland, G.

1993-12-01

Many economic decision support tools developed for the oil industry are based on the future oil price dynamics being represented by some specified stochastic process. To meet the demand for necessary data, much effort is allocated to parameter estimation based on historical oil price time series. The approach in this paper is to implement a complex future oil market model, and to condense the information from the model to parameter estimates for the future oil price. In particular, we use the Lensberg and Rasmussen stochastic dynamic oil market model to generate a large set of possible future oil price paths. Given the hypothesis that the future oil price is generated by a mean-reverting Ornstein-Uhlenbeck process, we obtain parameter estimates by a maximum likelihood procedure. We find a substantial degree of mean-reversion in the future oil price, which in some of our decision examples leads to an almost negligible value of flexibility. 12 refs., 2 figs., 3 tabs

Stochastic IMT (Insulator-Metal-Transition Neurons: An Interplay of Thermal and Threshold Noise at Bifurcation

Directory of Open Access Journals (Sweden)

Abhinav Parihar

2018-04-01

Full Text Available Artificial neural networks can harness stochasticity in multiple ways to enable a vast class of computationally powerful models. Boltzmann machines and other stochastic neural networks have been shown to outperform their deterministic counterparts by allowing dynamical systems to escape local energy minima. Electronic implementation of such stochastic networks is currently limited to addition of algorithmic noise to digital machines which is inherently inefficient; albeit recent efforts to harness physical noise in devices for stochasticity have shown promise. To succeed in fabricating electronic neuromorphic networks we need experimental evidence of devices with measurable and controllable stochasticity which is complemented with the development of reliable statistical models of such observed stochasticity. Current research literature has sparse evidence of the former and a complete lack of the latter. This motivates the current article where we demonstrate a stochastic neuron using an insulator-metal-transition (IMT device, based on electrically induced phase-transition, in series with a tunable resistance. We show that an IMT neuron has dynamics similar to a piecewise linear FitzHugh-Nagumo (FHN neuron and incorporates all characteristics of a spiking neuron in the device phenomena. We experimentally demonstrate spontaneous stochastic spiking along with electrically controllable firing probabilities using Vanadium Dioxide (VO2 based IMT neurons which show a sigmoid-like transfer function. The stochastic spiking is explained by two noise sources - thermal noise and threshold fluctuations, which act as precursors of bifurcation. As such, the IMT neuron is modeled as an Ornstein-Uhlenbeck (OU process with a fluctuating boundary resulting in transfer curves that closely match experiments. The moments of interspike intervals are calculated analytically by extending the first-passage-time (FPT models for Ornstein-Uhlenbeck (OU process to include a

Stochastic Models for Laser Propagation in Atmospheric Turbulence.

Science.gov (United States)

Leland, Robert Patton

In this dissertation, stochastic models for laser propagation in atmospheric turbulence are considered. A review of the existing literature on laser propagation in the atmosphere and white noise theory is presented, with a view toward relating the white noise integral and Ito integral approaches. The laser beam intensity is considered as the solution to a random Schroedinger equation, or forward scattering equation. This model is formulated in a Hilbert space context as an abstract bilinear system with a multiplicative white noise input, as in the literature. The model is also modeled in the Banach space of Fresnel class functions to allow the plane wave case and the application of path integrals. Approximate solutions to the Schroedinger equation of the Trotter-Kato product form are shown to converge for each white noise sample path. The product forms are shown to be physical random variables, allowing an Ito integral representation. The corresponding Ito integrals are shown to converge in mean square, providing a white noise basis for the Stratonovich correction term associated with this equation. Product form solutions for Ornstein -Uhlenbeck process inputs were shown to converge in mean square as the input bandwidth was expanded. A digital simulation of laser propagation in strong turbulence was used to study properties of the beam. Empirical distributions for the irradiance function were estimated from simulated data, and the log-normal and Rice-Nakagami distributions predicted by the classical perturbation methods were seen to be inadequate. A gamma distribution fit the simulated irradiance distribution well in the vicinity of the boresight. Statistics of the beam were seen to converge rapidly as the bandwidth of an Ornstein-Uhlenbeck process was expanded to its white noise limit. Individual trajectories of the beam were presented to illustrate the distortion and bending of the beam due to turbulence. Feynman path integrals were used to calculate an

A multiscale guide to Brownian motion

International Nuclear Information System (INIS)

Grebenkov, Denis S; Belyaev, Dmitry; Jones, Peter W

2016-01-01

We revise the Lévy construction of Brownian motion as a simple though rigorous approach to operate with various Gaussian processes. A Brownian path is explicitly constructed as a linear combination of wavelet-based ‘geometrical features’ at multiple length scales with random weights. Such a wavelet representation gives a closed formula mapping of the unit interval onto the functional space of Brownian paths. This formula elucidates many classical results about Brownian motion (e.g., non-differentiability of its path), providing an intuitive feeling for non-mathematicians. The illustrative character of the wavelet representation, along with the simple structure of the underlying probability space, is different from the usual presentation of most classical textbooks. Similar concepts are discussed for the Brownian bridge, fractional Brownian motion, the Ornstein-Uhlenbeck process, Gaussian free fields, and fractional Gaussian fields. Wavelet representations and dyadic decompositions form the basis of many highly efficient numerical methods to simulate Gaussian processes and fields, including Brownian motion and other diffusive processes in confining domains. (topical review)

Path-integral and Ornstein-Zernike study of quantum fluid structures on the crystallization line

International Nuclear Information System (INIS)

Sesé, Luis M.

2016-01-01

Liquid neon, liquid para-hydrogen, and the quantum hard-sphere fluid are studied with path integral Monte Carlo simulations and the Ornstein-Zernike pair equation on their respective crystallization lines. The results cover the whole sets of structures in the r-space and the k-space and, for completeness, the internal energies, pressures and isothermal compressibilities. Comparison with experiment is made wherever possible, and the possibilities of establishing k-space criteria for quantum crystallization based on the path-integral centroids are discussed. In this regard, the results show that the centroid structure factor contains two significant parameters related to its main peak features (amplitude and shape) that can be useful to characterize freezing.

Path-integral and Ornstein-Zernike study of quantum fluid structures on the crystallization line

Energy Technology Data Exchange (ETDEWEB)

Sesé, Luis M., E-mail: msese@ccia.uned.es [Departamento de Ciencias y Técnicas Fisicoquímicas, Universidad Nacional de Educación a Distancia, Paseo Senda del Rey 9, 28040 Madrid (Spain)

2016-03-07

Liquid neon, liquid para-hydrogen, and the quantum hard-sphere fluid are studied with path integral Monte Carlo simulations and the Ornstein-Zernike pair equation on their respective crystallization lines. The results cover the whole sets of structures in the r-space and the k-space and, for completeness, the internal energies, pressures and isothermal compressibilities. Comparison with experiment is made wherever possible, and the possibilities of establishing k-space criteria for quantum crystallization based on the path-integral centroids are discussed. In this regard, the results show that the centroid structure factor contains two significant parameters related to its main peak features (amplitude and shape) that can be useful to characterize freezing.

Fast and accurate calculation of dilute quantum gas using Uehling–Uhlenbeck model equation

Energy Technology Data Exchange (ETDEWEB)

Yano, Ryosuke, E-mail: ryosuke.yano@tokiorisk.co.jp

2017-02-01

The Uehling–Uhlenbeck (U–U) model equation is studied for the fast and accurate calculation of a dilute quantum gas. In particular, the direct simulation Monte Carlo (DSMC) method is used to solve the U–U model equation. DSMC analysis based on the U–U model equation is expected to enable the thermalization to be accurately obtained using a small number of sample particles and the dilute quantum gas dynamics to be calculated in a practical time. Finally, the applicability of DSMC analysis based on the U–U model equation to the fast and accurate calculation of a dilute quantum gas is confirmed by calculating the viscosity coefficient of a Bose gas on the basis of the Green–Kubo expression and the shock layer of a dilute Bose gas around a cylinder.

Adaptive evolution in locomotor performance: How selective pressures and functional relationships produce diversity.

Science.gov (United States)

Scales, Jeffrey A; Butler, Marguerite A

2016-01-01

Despite the complexity of nature, most comparative studies of phenotypic evolution consider selective pressures in isolation. When competing pressures operate on the same system, it is commonly expected that trade-offs will occur that will limit the evolution of phenotypic diversity, however, it is possible that interactions among selective pressures may promote diversity instead. We explored the evolution of locomotor performance in lizards in relation to possible selective pressures using the Ornstein-Uhlenbeck process. Here, we show that a combination of selection based on foraging mode and predator escape is required to explain variation in performance phenotypes. Surprisingly, habitat use contributed little explanatory power. We find that it is possible to evolve very different abilities in performance which were previously thought to be tightly correlated, supporting a growing literature that explores the many-to-one mapping of morphological design. Although we generally find the expected trade-off between maximal exertion and speed, this relationship surprisingly disappears when species experience selection for both performance types. We conclude that functional integration need not limit adaptive potential, and that an integrative approach considering multiple major influences on a phenotype allows a more complete understanding of adaptation and the evolution of diversity. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Relaxometry imaging of superparamagnetic magnetite nanoparticles at ambient conditions

Science.gov (United States)

Finkler, Amit; Schmid-Lorch, Dominik; Häberle, Thomas; Reinhard, Friedemann; Zappe, Andrea; Slota, Michael; Bogani, Lapo; Wrachtrup, Jörg

We present a novel technique to image superparamagnetic iron oxide nanoparticles via their fluctuating magnetic fields. The detection is based on the nitrogen-vacancy (NV) color center in diamond, which allows optically detected magnetic resonance (ODMR) measurements on its electron spin structure. In combination with an atomic-force-microscope, this atomic-sized color center maps ambient magnetic fields in a wide frequency range from DC up to several GHz, while retaining a high spatial resolution in the sub-nanometer range. We demonstrate imaging of single 10 nm sized magnetite nanoparticles using this spin noise detection technique. By fitting simulations (Ornstein-Uhlenbeck process) to the data, we are able to infer additional information on such a particle and its dynamics, like the attempt frequency and the anisotropy constant. This is of high interest to the proposed application of magnetite nanoparticles as an alternative MRI contrast agent or to the field of particle-aided tumor hyperthermia.

Equivalence of interest rate models and lattice gases.

Science.gov (United States)

Pirjol, Dan

2012-04-01

We consider the class of short rate interest rate models for which the short rate is proportional to the exponential of a Gaussian Markov process x(t) in the terminal measure r(t)=a(t)exp[x(t)]. These models include the Black-Derman-Toy and Black-Karasinski models in the terminal measure. We show that such interest rate models are equivalent to lattice gases with attractive two-body interaction, V(t(1),t(2))=-Cov[x(t(1)),x(t(2))]. We consider in some detail the Black-Karasinski model with x(t) as an Ornstein-Uhlenbeck process, and show that it is similar to a lattice gas model considered by Kac and Helfand, with attractive long-range two-body interactions, V(x,y)=-α(e(-γ|x-y|)-e(-γ(x+y))). An explicit solution for the model is given as a sum over the states of the lattice gas, which is used to show that the model has a phase transition similar to that found previously in the Black-Derman-Toy model in the terminal measure.

Front Propagation in Stochastic Neural Fields

KAUST Repository

Bressloff, Paul C.

2012-01-01

We analyze the effects of extrinsic multiplicative noise on front propagation in a scalar neural field with excitatory connections. Using a separation of time scales, we represent the fluctuating front in terms of a diffusive-like displacement (wandering) of the front from its uniformly translating position at long time scales, and fluctuations in the front profile around its instantaneous position at short time scales. One major result of our analysis is a comparison between freely propagating fronts and fronts locked to an externally moving stimulus. We show that the latter are much more robust to noise, since the stochastic wandering of the mean front profile is described by an Ornstein-Uhlenbeck process rather than a Wiener process, so that the variance in front position saturates in the long time limit rather than increasing linearly with time. Finally, we consider a stochastic neural field that supports a pulled front in the deterministic limit, and show that the wandering of such a front is now subdiffusive. © 2012 Society for Industrial and Applied Mathematics.

Uhlenbeck-Ford model: Phase diagram and corresponding-states analysis

Science.gov (United States)

Paula Leite, Rodolfo; Santos-Flórez, Pedro Antonio; de Koning, Maurice

2017-09-01

Using molecular dynamics simulations and nonequilibrium thermodynamic-integration techniques we compute the Helmholtz free energies of the body-centered-cubic (bcc), face-centered-cubic (fcc), hexagonal close-packed, and fluid phases of the Uhlenbeck-Ford model (UFM) and use the results to construct its phase diagram. The pair interaction associated with the UFM is characterized by an ultrasoft, purely repulsive pair potential that diverges logarithmically at the origin. We find that the bcc and fcc are the only thermodynamically stable crystalline phases in the phase diagram. Furthermore, we report the existence of two reentrant transition sequences as a function of the number density, one featuring a fluid-bcc-fluid succession and another displaying a bcc-fcc-bcc sequence near the triple point. We find strong resemblances to the phase behavior of other soft, purely repulsive systems such as the Gaussian-core model (GCM), inverse-power-law, and Yukawa potentials. In particular, we find that the fcc-bcc-fluid triple point and the phase boundaries in its vicinity are in good agreement with the prediction supplied by a recently proposed corresponding-states principle [J. Chem. Phys. 134, 241101 (2011), 10.1063/1.3605659; Europhys. Lett. 100, 66004 (2012), 10.1209/0295-5075/100/66004]. The particularly strong resemblance between the behavior of the UFM and GCM models are also discussed.

A study of the disintegration of highly excited nuclei with the Vlasov-Uehling-Uhlenbeck equation

International Nuclear Information System (INIS)

Vinet, L.; Gregoire, C.; Schuck, P.; Remaud, B.; Sebille, F.

1987-01-01

The disintegration of hot and/or compressed nuclei is studied using (i) the Vlasov equation (VE) with imposed spherical symmetry, (ii) the VE in three dimensions (3D) and (iii) the VE in three dimensions supplemented by the Uehling-Uhlenbeck collision term (VUU). We find that case (ii) is slightly more unstable with respect to disintegration compared to case (i) whereas (iii) tends to make nuclei more stable. In all cases the thermal energies (15-20 MeV per nucleon) needed to totally disintegrate a nucleus seem to be higher than those found in static and hydrodynamic calculation. On the contrary, compressional energy very much helps disintegration. Some comments on the introduction of fluctuations and corresponding fragmentation are added. (orig.)

The Pathwise Numerical Approximation of Stationary Solutions of Semilinear Stochastic Evolution Equations

International Nuclear Information System (INIS)

Caraballo, T.; Kloeden, P.E.

2006-01-01

Under a one-sided dissipative Lipschitz condition on its drift, a stochastic evolution equation with additive noise of the reaction-diffusion type is shown to have a unique stochastic stationary solution which pathwise attracts all other solutions. A similar situation holds for each Galerkin approximation and each implicit Euler scheme applied to these Galerkin approximations. Moreover, the stationary solution of the Euler scheme converges pathwise to that of the Galerkin system as the stepsize tends to zero and the stationary solutions of the Galerkin systems converge pathwise to that of the evolution equation as the dimension increases. The analysis is carried out on random partial and ordinary differential equations obtained from their stochastic counterparts by subtraction of appropriate Ornstein-Uhlenbeck stationary solutions

A nonlinear oscillator with parametric coloured noise: some analytical results

International Nuclear Information System (INIS)

Mallick, Kirone; Marcq, Philippe

2005-01-01

The asymptotic behaviour of a nonlinear oscillator subject to a multiplicative Ornstein-Uhlenbeck noise is investigated. When the dynamics is expressed in terms of energy-angle coordinates, it is observed that the angle is a fast variable as compared to the energy. Thus, an effective stochastic dynamics for the energy can be derived if the angular variable is averaged out. However, the standard elimination procedure, performed earlier for a Gaussian white noise, fails when the noise is coloured because of correlations between the noise and the fast angular variable. We develop here a specific averaging scheme that retains these correlations. This allows us to calculate the probability distribution function (PDF) of the system and to derive the behaviour of physical observables in the long time limit

Relaxometry and Dephasing Imaging of Superparamagnetic Magnetite Nanoparticles Using a Single Qubit

Science.gov (United States)

Schmid-Lorch, Dominik; Häberle, Thomas; Reinhard, Friedemann; Zappe, Andrea; Slota, Michael; Bogani, Lapo; Finkler, Amit; Wrachtrup, Jörg

2015-08-01

To study the magnetic dynamics of superparamagnetic nanoparticles we use scanning probe relaxometry and dephasing of the nitrogen-vacancy (NV) center in diamond, characterizing the spin-noise of a single 10-nm magnetite particle. Additionally, we show the anisotropy of the NV sensitivity's dependence on the applied decoherence measurement method. By comparing the change in relaxation (T 1 ) and dephasing (T 2 ) time in the NV center when scanning a nanoparticle over it, we are able to extract the nanoparticle's diameter and distance from the NV center using an Ornstein-Uhlenbeck model for the nanoparticle's fluctuations. This scanning-probe technique can be used in the future to characterize different spin label substitutes for both medical applications and basic magnetic nanoparticle behavior.

Evolutionary patterns and processes in the radiation of phyllostomid bats

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Monteiro Leandro R

2011-05-01

Full Text Available Abstract Background The phyllostomid bats present the most extensive ecological and phenotypic radiation known among mammal families. This group is an important model system for studies of cranial ecomorphology and functional optimisation because of the constraints imposed by the requirements of flight. A number of studies supporting phyllostomid adaptation have focused on qualitative descriptions or correlating functional variables and diet, but explicit tests of possible evolutionary mechanisms and scenarios for phenotypic diversification have not been performed. We used a combination of morphometric and comparative methods to test hypotheses regarding the evolutionary processes behind the diversification of phenotype (mandible shape and size and diet during the phyllostomid radiation. Results The different phyllostomid lineages radiate in mandible shape space, with each feeding specialisation evolving towards different axes. Size and shape evolve quite independently, as the main directions of shape variation are associated with mandible elongation (nectarivores or the relative size of tooth rows and mandibular processes (sanguivores and frugivores, which are not associated with size changes in the mandible. The early period of phyllostomid diversification is marked by a burst of shape, size, and diet disparity (before 20 Mya, larger than expected by neutral evolution models, settling later to a period of relative phenotypic and ecological stasis. The best fitting evolutionary model for both mandible shape and size divergence was an Ornstein-Uhlenbeck process with five adaptive peaks (insectivory, carnivory, sanguivory, nectarivory and frugivory. Conclusions The radiation of phyllostomid bats presented adaptive and non-adaptive components nested together through the time frame of the family's evolution. The first 10 My of the radiation were marked by strong phenotypic and ecological divergence among ancestors of modern lineages, whereas the

Evolutionary patterns and processes in the radiation of phyllostomid bats

Science.gov (United States)

2011-01-01

Background The phyllostomid bats present the most extensive ecological and phenotypic radiation known among mammal families. This group is an important model system for studies of cranial ecomorphology and functional optimisation because of the constraints imposed by the requirements of flight. A number of studies supporting phyllostomid adaptation have focused on qualitative descriptions or correlating functional variables and diet, but explicit tests of possible evolutionary mechanisms and scenarios for phenotypic diversification have not been performed. We used a combination of morphometric and comparative methods to test hypotheses regarding the evolutionary processes behind the diversification of phenotype (mandible shape and size) and diet during the phyllostomid radiation. Results The different phyllostomid lineages radiate in mandible shape space, with each feeding specialisation evolving towards different axes. Size and shape evolve quite independently, as the main directions of shape variation are associated with mandible elongation (nectarivores) or the relative size of tooth rows and mandibular processes (sanguivores and frugivores), which are not associated with size changes in the mandible. The early period of phyllostomid diversification is marked by a burst of shape, size, and diet disparity (before 20 Mya), larger than expected by neutral evolution models, settling later to a period of relative phenotypic and ecological stasis. The best fitting evolutionary model for both mandible shape and size divergence was an Ornstein-Uhlenbeck process with five adaptive peaks (insectivory, carnivory, sanguivory, nectarivory and frugivory). Conclusions The radiation of phyllostomid bats presented adaptive and non-adaptive components nested together through the time frame of the family's evolution. The first 10 My of the radiation were marked by strong phenotypic and ecological divergence among ancestors of modern lineages, whereas the remaining 20 My were

Dynamic Looping of a Free-Draining Polymer

Energy Technology Data Exchange (ETDEWEB)

Ye, Felix X. -F.; Stinis, Panos; Qian, Hong

2018-01-11

Here, we revisit the celebrated Wilemski--Fixman (WF) treatment for the looping time of a free-draining polymer. The WF theory introduces a sink term into the Fokker--Planck equation for the $3(N+1)$-dimensional Ornstein--Uhlenbeck process of polymer dynamics, which accounts for the appropriate boundary condition due to the formation of a loop. The assumption for WF theory is considerably relaxed. A perturbation method approach is developed that justifies and generalizes the previous results using either a delta sink or a Heaviside sink. For both types of sinks, we show that under the condition of a small dimensionless $\\epsilon$, the ratio of capture radius to the Kuhn length, we are able to systematically produce all known analytical and asymptotic results obtained by other methods. This includes most notably the transition regime between the $N^2$ scaling of Doi, and $N\\sqrt{N}/\\epsilon$ scaling of Szabo, Schulten, and Schulten. The mathematical issue at play is the nonuniform convergence of $\\epsilon\\to 0$ and $N\\to\\infty$, the latter being an inherent part of the theory of a Gaussian polymer. Our analysis yields a novel term in the analytical expression for the looping time with small $\\epsilon$, which was previously unknown. Monte Carlo numerical simulations corroborate the analytical findings. The systematic method developed here can be applied to other systems modeled by multidimensional Smoluchowski equations.

Bilayer graphene lattice-layer entanglement in the presence of non-Markovian phase noise

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Bittencourt, Victor A. S. V.; Blasone, Massimo; Bernardini, Alex E.

2018-03-01

The evolution of single particle excitations of bilayer graphene under effects of non-Markovian noise is described with focus on the decoherence process of lattice-layer (LL) maximally entangled states. Once the noiseless dynamics of an arbitrary initial state is identified by the correspondence between the tight-binding Hamiltonian for the AB-stacked bilayer graphene and the Dirac equation—which includes pseudovectorlike and tensorlike field interactions—the noisy environment is described as random fluctuations on bias voltage and mass terms. The inclusion of noisy dynamics reproduces the Ornstein-Uhlenbeck processes: A non-Markovian noise model with a well-defined Markovian limit. Considering that an initial amount of entanglement shall be dissipated by the noise, two profiles of dissipation are identified. On one hand, for eigenstates of the noiseless Hamiltonian, deaths and revivals of entanglement are identified along the oscillation pattern for long interaction periods. On the other hand, for departing LL Werner and Cat states, the entanglement is suppressed although, for both cases, some identified memory effects compete with the pure noise-induced decoherence in order to preserve the the overall profile of a given initial state.

On the distribution of interspecies correlation for Markov models of character evolution on Yule trees.

Science.gov (United States)

Mulder, Willem H; Crawford, Forrest W

2015-01-07

Efforts to reconstruct phylogenetic trees and understand evolutionary processes depend fundamentally on stochastic models of speciation and mutation. The simplest continuous-time model for speciation in phylogenetic trees is the Yule process, in which new species are "born" from existing lineages at a constant rate. Recent work has illuminated some of the structural properties of Yule trees, but it remains mostly unknown how these properties affect sequence and trait patterns observed at the tips of the phylogenetic tree. Understanding the interplay between speciation and mutation under simple models of evolution is essential for deriving valid phylogenetic inference methods and gives insight into the optimal design of phylogenetic studies. In this work, we derive the probability distribution of interspecies covariance under Brownian motion and Ornstein-Uhlenbeck models of phenotypic change on a Yule tree. We compute the probability distribution of the number of mutations shared between two randomly chosen taxa in a Yule tree under discrete Markov mutation models. Our results suggest summary measures of phylogenetic information content, illuminate the correlation between site patterns in sequences or traits of related organisms, and provide heuristics for experimental design and reconstruction of phylogenetic trees. Copyright © 2014 Elsevier Ltd. All rights reserved.

Structure of highly asymmetric hard-sphere mixtures: an efficient closure of the Ornstein-Zernike equations.

Science.gov (United States)

Amokrane, S; Ayadim, A; Malherbe, J G

2005-11-01

A simple modification of the reference hypernetted chain (RHNC) closure of the multicomponent Ornstein-Zernike equations with bridge functions taken from Rosenfeld's hard-sphere bridge functional is proposed. Its main effect is to remedy the major limitation of the RHNC closure in the case of highly asymmetric mixtures--the wide domain of packing fractions in which it has no solution. The modified closure is also much faster, while being of similar complexity. This is achieved with a limited loss of accuracy, mainly for the contact value of the big sphere correlation functions. Comparison with simulation shows that inside the RHNC no-solution domain, it provides a good description of the structure, while being clearly superior to all the other closures used so far to study highly asymmetric mixtures. The generic nature of this closure and its good accuracy combined with a reduced no-solution domain open up the possibility to study the phase diagram of complex fluids beyond the hard-sphere model.

Stochastic kinetics of photoinduced phase transitions in spin-crossover solids

Science.gov (United States)

Gudyma, Iurii; Maksymov, Artur; Dimian, Mihai

2013-10-01

We study the stochastic macroscopic kinetics of photoinduced phase transitions in spin-crossover compounds assisted by white and colored Ornstein-Uhlenbeck noise. By using a phenomenological master equation obtained in the mean-field approach, the phase diagram is constructed based on the associated Lyapunov function. The stochastic behavior is then analyzed in the Langevin framework and the corresponding Fokker-Planck equations. Both additive and multiplicative and white and colored types of noise are considered and the stationary probability densities are found along with the noise-assisted light induced hysteretic loops. By using the Kramers formalism, we also focus our attention on the escape time problem in these noise perturbed systems. A detailed study of the relative escape time dependence on various noise characteristics is performed and the main features are compared for different types of noise.

A unified view on weakly correlated recurrent networks

Directory of Open Access Journals (Sweden)

Dmytro eGrytskyy

2013-10-01

Full Text Available The diversity of neuron models used in contemporary theoretical neuroscience to investigate specific properties of covariances in the spiking activity raises the question how these models relate to each other. In particular it is hard to distinguish between generic properties of covariances and peculiarities due to the abstracted model. Here we present a unified view on pairwise covariances in recurrent networks in the irregular regime. We consider the binary neuron model, the leaky integrate-and-fire model, and the Hawkes process. We show that linear approximation maps each of these models to either of two classes of linear rate models, including the Ornstein-Uhlenbeck process as a special case. The distinction between both classes is the location of additive noise in the rate dynamics, which is located on the output side for spiking models and on the input side for the binary model. Both classes allow closed form solutions for the covariance. For output noise it separates into an echo term and a term due to correlated input. The unified framework enables us to transfer results between models. For example, we generalize the binary model and the Hawkes process to the situation with synaptic conduction delays and simplify derivations for established results. Our approach is applicable to general network structures and suitable for the calculation of population averages. The derived averages are exact for fixed out-degree network architectures and approximate for fixed in-degree. We demonstrate how taking into account fluctuations in the linearization procedure increases the accuracy of the effective theory and we explain the class dependent differences between covariances in the time and the frequency domain. Finally we show that the oscillatory instability emerging in networks of integrate-and-fire models with delayed inhibitory feedback is a model-invariant feature: the same structure of poles in the complex frequency plane determines the

Beth-Uhlenbeck approach for repulsive interactions between baryons in a hadron gas

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Vovchenko, Volodymyr; Motornenko, Anton; Gorenstein, Mark I.; Stoecker, Horst

2018-03-01

The quantum mechanical Beth-Uhlenbeck (BU) approach for repulsive hard-core interactions between baryons is applied to the thermodynamics of a hadron gas. The second virial coefficient a2—the "excluded volume" parameter—calculated within the BU approach is found to be temperature dependent, and it differs dramatically from the classical excluded volume (EV) model result. At temperatures T =100 -200 MeV, the widely used classical EV model underestimates the EV parameter for nucleons at a given value of the nucleon hard-core radius by large factors of 3-4. Previous studies, which employed the hard-core radii of hadrons as an input into the classical EV model, have to be re-evaluated using the appropriately rescaled EV parameters. The BU approach is used to model the repulsive baryonic interactions in the hadron resonance gas (HRG) model. Lattice data for the second- and fourth-order net baryon susceptibilities are described fairly well when the temperature dependent BU baryonic excluded volume parameter corresponds to nucleon hard-core radii of rc=0.25 -0.3 fm. Role of the attractive baryonic interactions is also considered. It is argued that HRG model with a constant baryon-baryon EV parameter vN N≃1 fm3 provides a simple yet efficient description of baryon-baryon interaction in the crossover temperature region.

Micro-foundation using percolation theory of the finite time singular behavior of the crash hazard rate in a class of rational expectation bubbles

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Seyrich, Maximilian; Sornette, Didier

2016-04-01

We present a plausible micro-founded model for the previously postulated power law finite time singular form of the crash hazard rate in the Johansen-Ledoit-Sornette (JLS) model of rational expectation bubbles. The model is based on a percolation picture of the network of traders and the concept that clusters of connected traders share the same opinion. The key ingredient is the notion that a shift of position from buyer to seller of a sufficiently large group of traders can trigger a crash. This provides a formula to estimate the crash hazard rate by summation over percolation clusters above a minimum size of a power sa (with a>1) of the cluster sizes s, similarly to a generalized percolation susceptibility. The power sa of cluster sizes emerges from the super-linear dependence of group activity as a function of group size, previously documented in the literature. The crash hazard rate exhibits explosive finite time singular behaviors when the control parameter (fraction of occupied sites, or density of traders in the network) approaches the percolation threshold pc. Realistic dynamics are generated by modeling the density of traders on the percolation network by an Ornstein-Uhlenbeck process, whose memory controls the spontaneous excursion of the control parameter close to the critical region of bubble formation. Our numerical simulations recover the main stylized properties of the JLS model with intermittent explosive super-exponential bubbles interrupted by crashes.

Simplified rotor load models and fatigue damage estimates for offshore wind turbines.

Science.gov (United States)

Muskulus, M

2015-02-28

The aim of rotor load models is to characterize and generate the thrust loads acting on an offshore wind turbine. Ideally, the rotor simulation can be replaced by time series from a model with a few parameters and state variables only. Such models are used extensively in control system design and, as a potentially new application area, structural optimization of support structures. Different rotor load models are here evaluated for a jacket support structure in terms of fatigue lifetimes of relevant structural variables. All models were found to be lacking in accuracy, with differences of more than 20% in fatigue load estimates. The most accurate models were the use of an effective thrust coefficient determined from a regression analysis of dynamic thrust loads, and a novel stochastic model in state-space form. The stochastic model explicitly models the quasi-periodic components obtained from rotational sampling of turbulent fluctuations. Its state variables follow a mean-reverting Ornstein-Uhlenbeck process. Although promising, more work is needed on how to determine the parameters of the stochastic model and before accurate lifetime predictions can be obtained without comprehensive rotor simulations. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Stochastic particle acceleration and statistical closures

International Nuclear Information System (INIS)

Dimits, A.M.; Krommes, J.A.

1985-10-01

In a recent paper, Maasjost and Elsasser (ME) concluded, from the results of numerical experiments and heuristic arguments, that the Bourret and the direct-interaction approximation (DIA) are ''of no use in connection with the stochastic acceleration problem'' because (1) their predictions were equivalent to that of the simpler Fokker-Planck (FP) theory, and (2) either all or none of the closures were in good agreement with the data. Here some analytically tractable cases are studied and used to test the accuracy of these closures. The cause of the discrepancy (2) is found to be the highly non-Gaussian nature of the force used by ME, a point not stressed by them. For the case where the force is a position-independent Ornstein-Uhlenbeck (i.e., Gaussian) process, an effective Kubo number K can be defined. For K << 1 an FP description is adequate, and conclusion (1) of ME follows; however, for K greater than or equal to 1 the DIA behaves much better qualitatively than the other two closures. For the non-Gaussian stochastic force used by ME, all common approximations fail, in agreement with (2)

Enhancement of Quantum Correlations in Qubit-Qutrit Systems under the non-Markovian Environment

Institute of Scientific and Technical Information of China (English)

Abdul Basit; Hamad Ali; Fazal Badshah; Guo-Qin Ge

2017-01-01

We investigate the time evolution of quantum correlations of a hybrid qubit-qutrit system under the classical Ornstein-Uhlenbeck (OU) noise.Here we consider two different one-parameter families of qubit-qutrit states which independently interact with the non-Markovian reservoirs.A comparison with the Markovian dynamics reveals that for the same set of initial condition parameters,the non-Markovian behavior of the environment plays an important role in the enhancement of the survival time of quantum correlations.In addition,it is observed that the non-Markovian strength (γ/F) has a positive impact on the correlations time.For the initial separable states it is found that there is a finite time interval in which the geometric quantum discord is frozen despite the presence of a noisy environment and that interval can be further prolonged by using the non-Markovian property.Moreover,its decay can be significantly delayed.

A hybrid framework of first principles molecular orbital calculations and a three-dimensional integral equation theory for molecular liquids: Multi-center molecular Ornstein-Zernike self-consistent field approach

Science.gov (United States)

Kido, Kentaro; Kasahara, Kento; Yokogawa, Daisuke; Sato, Hirofumi

2015-07-01

In this study, we reported the development of a new quantum mechanics/molecular mechanics (QM/MM)-type framework to describe chemical processes in solution by combining standard molecular-orbital calculations with a three-dimensional formalism of integral equation theory for molecular liquids (multi-center molecular Ornstein-Zernike (MC-MOZ) method). The theoretical procedure is very similar to the 3D-reference interaction site model self-consistent field (RISM-SCF) approach. Since the MC-MOZ method is highly parallelized for computation, the present approach has the potential to be one of the most efficient procedures to treat chemical processes in solution. Benchmark tests to check the validity of this approach were performed for two solute (solute water and formaldehyde) systems and a simple SN2 reaction (Cl- + CH3Cl → ClCH3 + Cl-) in aqueous solution. The results for solute molecular properties and solvation structures obtained by the present approach were in reasonable agreement with those obtained by other hybrid frameworks and experiments. In particular, the results of the proposed approach are in excellent agreements with those of 3D-RISM-SCF.

A hybrid framework of first principles molecular orbital calculations and a three-dimensional integral equation theory for molecular liquids: multi-center molecular Ornstein-Zernike self-consistent field approach.

Science.gov (United States)

Kido, Kentaro; Kasahara, Kento; Yokogawa, Daisuke; Sato, Hirofumi

2015-07-07

In this study, we reported the development of a new quantum mechanics/molecular mechanics (QM/MM)-type framework to describe chemical processes in solution by combining standard molecular-orbital calculations with a three-dimensional formalism of integral equation theory for molecular liquids (multi-center molecular Ornstein-Zernike (MC-MOZ) method). The theoretical procedure is very similar to the 3D-reference interaction site model self-consistent field (RISM-SCF) approach. Since the MC-MOZ method is highly parallelized for computation, the present approach has the potential to be one of the most efficient procedures to treat chemical processes in solution. Benchmark tests to check the validity of this approach were performed for two solute (solute water and formaldehyde) systems and a simple SN2 reaction (Cl(-) + CH3Cl → ClCH3 + Cl(-)) in aqueous solution. The results for solute molecular properties and solvation structures obtained by the present approach were in reasonable agreement with those obtained by other hybrid frameworks and experiments. In particular, the results of the proposed approach are in excellent agreements with those of 3D-RISM-SCF.

A comparison of ancestral state reconstruction methods for quantitative characters.

Science.gov (United States)

Royer-Carenzi, Manuela; Didier, Gilles

2016-09-07

Choosing an ancestral state reconstruction method among the alternatives available for quantitative characters may be puzzling. We present here a comparison of seven of them, namely the maximum likelihood, restricted maximum likelihood, generalized least squares under Brownian, Brownian-with-trend and Ornstein-Uhlenbeck models, phylogenetic independent contrasts and squared parsimony methods. A review of the relations between these methods shows that the maximum likelihood, the restricted maximum likelihood and the generalized least squares under Brownian model infer the same ancestral states and can only be distinguished by the distributions accounting for the reconstruction uncertainty which they provide. The respective accuracy of the methods is assessed over character evolution simulated under a Brownian motion with (and without) directional or stabilizing selection. We give the general form of ancestral state distributions conditioned on leaf states under the simulation models. Ancestral distributions are used first, to give a theoretical lower bound of the expected reconstruction error, and second, to develop an original evaluation scheme which is more efficient than comparing the reconstructed and the simulated states. Our simulations show that: (i) the distributions of the reconstruction uncertainty provided by the methods generally make sense (some more than others); (ii) it is essential to detect the presence of an evolutionary trend and to choose a reconstruction method accordingly; (iii) all the methods show good performances on characters under stabilizing selection; (iv) without trend or stabilizing selection, the maximum likelihood method is generally the most accurate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Noise in strong laser-atom interactions: Phase telegraph noise

International Nuclear Information System (INIS)

Eberly, J.H.; Wodkiewicz, K.; Shore, B.W.

1984-01-01

We discuss strong laser-atom interactions that are subjected to jump-type (random telegraph) random-phase noise. Physically, the jumps may arise from laser fluctuations, from collisions of various kinds, or from other external forces. Our discussion is carried out in two stages. First, direct and partially heuristic calculations determine the laser spectrum and also give a third-order differential equation for the average inversion of a two-level atom on resonance. At this stage a number of general features of the interaction are able to be studied easily. The optical analog of motional narrowing, for example, is clearly predicted. Second, we show that the theory of generalized Poisson processes allows laser-atom interactions in the presence of random telegraph noise of all kinds (not only phase noise) to be treated systematically, by means of a master equation first used in the context of quantum optics by Burshtein. We use the Burshtein equation to obtain an exact expression for the two-level atom's steady-state resonance fluorescence spectrum, when the exciting laser exhibits phase telegraph noise. Some comparisons are made with results obtained from other noise models. Detailed treatments of the effects ofmly jumps, or as a model of finite laser bandwidth effects, in which the laser frequency exhibits random jumps. We show that these two types of frequency noise can be distinguished in light-scattering spectra. We also discuss examples which demonstrate both temporal and spectral motional narrowing, nonexponential correlations, and non-Lorentzian spectra. Its exact solubility in finite terms makes the frequency-telegraph noise model an attractive alternative to the white-noise Ornstein-Uhlenbeck frequency noise model which has been previously applied to laser-atom interactions

Una fórmula exacta para el valor de una opción europea sobre una obligación en modelo multifactorial Orntein-Ulhenbeck

Directory of Open Access Journals (Sweden)

Gómez del Valle, L.

1998-01-01

Full Text Available En este trabajo se obtiene explícitamente el valor de una opción europea sobre una obligación que reparte cupones. Se supone que la estructura temporal de los tantos de interés viene determinada por el valor del tanto de interés instantáneo, el cual es una combinación lineal de n variables de estado. Estos factores son procesos estocásticos de tipo Ornstein-Uhlenbeck independientes y los precios del riesgo de mercado también son estocásticos. En primer lugar, aplicando un resultado de Friedman (1975 se resuelve de forma cerrada una ecuación general de valoración de activos derivados del tanto de interés. Posteriormente, se aplica al caso particular de la valoración de opciones sobre obligaciones que no reparten cupones y finalmente se obtiene el valor de las opciones sobre obligaciones que sí reparten cupones. Langetieg (1980 realizó un estudio con este modelo, pero con precios de riesgo de mercado constantes, utilizando otros procedimientos. Este trabajo supone una generalización de Jamshidian (1989, el cual obtuvo el valor de las opciones sobre obligaciones que reparten cupones para un modelo unifactorial.

Collective Activity of Many Bistable Assemblies Reproduces Characteristic Dynamics of Multistable Perception.

Science.gov (United States)

Cao, Robin; Pastukhov, Alexander; Mattia, Maurizio; Braun, Jochen

2016-06-29

The timing of perceptual decisions depends on both deterministic and stochastic factors, as the gradual accumulation of sensory evidence (deterministic) is contaminated by sensory and/or internal noise (stochastic). When human observers view multistable visual displays, successive episodes of stochastic accumulation culminate in repeated reversals of visual appearance. Treating reversal timing as a "first-passage time" problem, we ask how the observed timing densities constrain the underlying stochastic accumulation. Importantly, mean reversal times (i.e., deterministic factors) differ enormously between displays/observers/stimulation levels, whereas the variance and skewness of reversal times (i.e., stochastic factors) keep characteristic proportions of the mean. What sort of stochastic process could reproduce this highly consistent "scaling property?" Here we show that the collective activity of a finite population of bistable units (i.e., a generalized Ehrenfest process) quantitatively reproduces all aspects of the scaling property of multistable phenomena, in contrast to other processes under consideration (Poisson, Wiener, or Ornstein-Uhlenbeck process). The postulated units express the spontaneous dynamics of attractor assemblies transitioning between distinct activity states. Plausible candidates are cortical columns, or clusters of columns, as they are preferentially connected and spontaneously explore a restricted repertoire of activity states. Our findings suggests that perceptual representations are granular, probabilistic, and operate far from equilibrium, thereby offering a suitable substrate for statistical inference. Spontaneous reversals of high-level perception, so-called multistable perception, conform to highly consistent and characteristic statistics, constraining plausible neural representations. We show that the observed perceptual dynamics would be reproduced quantitatively by a finite population of distinct neural assemblies, each with

Statistical Inference for Partially Observed Diffusion Processes

DEFF Research Database (Denmark)

Jensen, Anders Christian

This thesis is concerned with parameter estimation for multivariate diffusion models. It gives a short introduction to diffusion models, and related mathematical concepts. we then introduce the method of prediction-based estimating functions and describe in detail the application for a two......-Uhlenbeck process, while chapter eight describes the detials of an R-package that was developed in relations to the application of the estimationprocedure of chapters five and six....

Direct numerical solution of the Ornstein-Zernike integral equation and spatial distribution of water around hydrophobic molecules

Science.gov (United States)

Ikeguchi, Mitsunori; Doi, Junta

1995-09-01

The Ornstein-Zernike integral equation (OZ equation) has been used to evaluate the distribution function of solvents around solutes, but its numerical solution is difficult for molecules with a complicated shape. This paper proposes a numerical method to directly solve the OZ equation by introducing the 3D lattice. The method employs no approximation the reference interaction site model (RISM) equation employed. The method enables one to obtain the spatial distribution of spherical solvents around solutes with an arbitrary shape. Numerical accuracy is sufficient when the grid-spacing is less than 0.5 Å for solvent water. The spatial water distribution around a propane molecule is demonstrated as an example of a nonspherical hydrophobic molecule using iso-value surfaces. The water model proposed by Pratt and Chandler is used. The distribution agrees with the molecular dynamics simulation. The distribution increases offshore molecular concavities. The spatial distribution of water around 5α-cholest-2-ene (C27H46) is visualized using computer graphics techniques and a similar trend is observed.

Effective equilibrium states in mixtures of active particles driven by colored noise

Science.gov (United States)

Wittmann, René; Brader, J. M.; Sharma, A.; Marconi, U. Marini Bettolo

2018-01-01

We consider the steady-state behavior of pairs of active particles having different persistence times and diffusivities. To this purpose we employ the active Ornstein-Uhlenbeck model, where the particles are driven by colored noises with exponential correlation functions whose intensities and correlation times vary from species to species. By extending Fox's theory to many components, we derive by functional calculus an approximate Fokker-Planck equation for the configurational distribution function of the system. After illustrating the predicted distribution in the solvable case of two particles interacting via a harmonic potential, we consider systems of particles repelling through inverse power-law potentials. We compare the analytic predictions to computer simulations for such soft-repulsive interactions in one dimension and show that at linear order in the persistence times the theory is satisfactory. This work provides the toolbox to qualitatively describe many-body phenomena, such as demixing and depletion, by means of effective pair potentials.

Geometric capture and escape of a microswimmer colliding with an obstacle.

Science.gov (United States)

Spagnolie, Saverio E; Moreno-Flores, Gregorio R; Bartolo, Denis; Lauga, Eric

2015-05-07

Motivated by recent experiments, we consider the hydrodynamic capture of a microswimmer near a stationary spherical obstacle. Simulations of model equations show that a swimmer approaching a small spherical colloid is simply scattered. In contrast, when the colloid is larger than a critical size it acts as a passive trap: the swimmer is hydrodynamically captured along closed trajectories and endlessly orbits around the colloidal sphere. In order to gain physical insight into this hydrodynamic scattering problem, we address it analytically. We provide expressions for the critical trapping radius, the depth of the "basin of attraction," and the scattering angle, which show excellent agreement with our numerical findings. We also demonstrate and rationalize the strong impact of swimming-flow symmetries on the trapping efficiency. Finally, we give the swimmer an opportunity to escape the colloidal traps by considering the effects of Brownian, or active, diffusion. We show that in some cases the trapping time is governed by an Ornstein-Uhlenbeck process, which results in a trapping time distribution that is well-approximated as inverse-Gaussian. The predictions again compare very favorably with the numerical simulations. We envision applications of the theory to bioremediation, microorganism sorting techniques, and the study of bacterial populations in heterogeneous or porous environments.

Analogies between colored Lévy noise and random channel approach to disordered kinetics

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Vlad, Marcel O.; Velarde, Manuel G.; Ross, John

2004-02-01

We point out some interesting analogies between colored Lévy noise and the random channel approach to disordered kinetics. These analogies are due to the fact that the probability density of the Lévy noise source plays a similar role as the probability density of rate coefficients in disordered kinetics. Although the equations for the two approaches are not identical, the analogies can be used for deriving new, useful results for both problems. The random channel approach makes it possible to generalize the fractional Uhlenbeck-Ornstein processes (FUO) for space- and time-dependent colored noise. We describe the properties of colored noise in terms of characteristic functionals, which are evaluated by using a generalization of Huber's approach to complex relaxation [Phys. Rev. B 31, 6070 (1985)]. We start out by investigating the properties of symmetrical white noise and then define the Lévy colored noise in terms of a Langevin equation with a Lévy white noise source. We derive exact analytical expressions for the various characteristic functionals, which characterize the noise, and a functional fractional Fokker-Planck equation for the probability density functional of the noise at a given moment in time. Second, by making an analogy between the theory of colored noise and the random channel approach to disordered kinetics, we derive fractional equations for the evolution of the probability densities of the random rate coefficients in disordered kinetics. These equations serve as a basis for developing methods for the evaluation of the statistical properties of the random rate coefficients from experimental data. Special attention is paid to the analysis of systems for which the observed kinetic curves can be described by linear or nonlinear stretched exponential kinetics.

Multivariate supOU processes

DEFF Research Database (Denmark)

Barndorff-Nielsen, Ole Eiler; Stelzer, Robert

2011-01-01

Univariate superpositions of Ornstein–Uhlenbeck-type processes (OU), called supOU processes, provide a class of continuous time processes capable of exhibiting long memory behavior. This paper introduces multivariate supOU processes and gives conditions for their existence and finiteness of moments....... Moreover, the second-order moment structure is explicitly calculated, and examples exhibit the possibility of long-range dependence. Our supOU processes are defined via homogeneous and factorizable Lévy bases. We show that the behavior of supOU processes is particularly nice when the mean reversion...... parameter is restricted to normal matrices and especially to strictly negative definite ones. For finite variation Lévy bases we are able to give conditions for supOU processes to have locally bounded càdlàg paths of finite variation and to show an analogue of the stochastic differential equation of OU...

The Beta Cell in Its Cluster: Stochastic Graphs of Beta Cell Connectivity in the Islets of Langerhans.

Directory of Open Access Journals (Sweden)

Deborah A Striegel

2015-08-01

Full Text Available Pancreatic islets of Langerhans consist of endocrine cells, primarily α, β and δ cells, which secrete glucagon, insulin, and somatostatin, respectively, to regulate plasma glucose. β cells form irregular locally connected clusters within islets that act in concert to secrete insulin upon glucose stimulation. Due to the central functional significance of this local connectivity in the placement of β cells in an islet, it is important to characterize it quantitatively. However, quantification of the seemingly stochastic cytoarchitecture of β cells in an islet requires mathematical methods that can capture topological connectivity in the entire β-cell population in an islet. Graph theory provides such a framework. Using large-scale imaging data for thousands of islets containing hundreds of thousands of cells in human organ donor pancreata, we show that quantitative graph characteristics differ between control and type 2 diabetic islets. Further insight into the processes that shape and maintain this architecture is obtained by formulating a stochastic theory of β-cell rearrangement in whole islets, just as the normal equilibrium distribution of the Ornstein-Uhlenbeck process can be viewed as the result of the interplay between a random walk and a linear restoring force. Requiring that rearrangements maintain the observed quantitative topological graph characteristics strongly constrained possible processes. Our results suggest that β-cell rearrangement is dependent on its connectivity in order to maintain an optimal cluster size in both normal and T2D islets.

The Beta Cell in Its Cluster: Stochastic Graphs of Beta Cell Connectivity in the Islets of Langerhans.

Science.gov (United States)

Striegel, Deborah A; Hara, Manami; Periwal, Vipul

2015-08-01

Pancreatic islets of Langerhans consist of endocrine cells, primarily α, β and δ cells, which secrete glucagon, insulin, and somatostatin, respectively, to regulate plasma glucose. β cells form irregular locally connected clusters within islets that act in concert to secrete insulin upon glucose stimulation. Due to the central functional significance of this local connectivity in the placement of β cells in an islet, it is important to characterize it quantitatively. However, quantification of the seemingly stochastic cytoarchitecture of β cells in an islet requires mathematical methods that can capture topological connectivity in the entire β-cell population in an islet. Graph theory provides such a framework. Using large-scale imaging data for thousands of islets containing hundreds of thousands of cells in human organ donor pancreata, we show that quantitative graph characteristics differ between control and type 2 diabetic islets. Further insight into the processes that shape and maintain this architecture is obtained by formulating a stochastic theory of β-cell rearrangement in whole islets, just as the normal equilibrium distribution of the Ornstein-Uhlenbeck process can be viewed as the result of the interplay between a random walk and a linear restoring force. Requiring that rearrangements maintain the observed quantitative topological graph characteristics strongly constrained possible processes. Our results suggest that β-cell rearrangement is dependent on its connectivity in order to maintain an optimal cluster size in both normal and T2D islets.

Experiments to Distribute Map Generalization Processes

Science.gov (United States)

Berli, Justin; Touya, Guillaume; Lokhat, Imran; Regnauld, Nicolas

2018-05-01

Automatic map generalization requires the use of computationally intensive processes often unable to deal with large datasets. Distributing the generalization process is the only way to make them scalable and usable in practice. But map generalization is a highly contextual process, and the surroundings of a generalized map feature needs to be known to generalize the feature, which is a problem as distribution might partition the dataset and parallelize the processing of each part. This paper proposes experiments to evaluate the past propositions to distribute map generalization, and to identify the main remaining issues. The past propositions to distribute map generalization are first discussed, and then the experiment hypotheses and apparatus are described. The experiments confirmed that regular partitioning was the quickest strategy, but also the less effective in taking context into account. The geographical partitioning, though less effective for now, is quite promising regarding the quality of the results as it better integrates the geographical context.

Mutual information identifies spurious Hurst phenomena in resting state EEG and fMRI data

Science.gov (United States)

von Wegner, Frederic; Laufs, Helmut; Tagliazucchi, Enzo

2018-02-01

Long-range memory in time series is often quantified by the Hurst exponent H , a measure of the signal's variance across several time scales. We analyze neurophysiological time series from electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) resting state experiments with two standard Hurst exponent estimators and with the time-lagged mutual information function applied to discretized versions of the signals. A confidence interval for the mutual information function is obtained from surrogate Markov processes with equilibrium distribution and transition matrix identical to the underlying signal. For EEG signals, we construct an additional mutual information confidence interval from a short-range correlated, tenth-order autoregressive model. We reproduce the previously described Hurst phenomenon (H >0.5 ) in the analytical amplitude of alpha frequency band oscillations, in EEG microstate sequences, and in fMRI signals, but we show that the Hurst phenomenon occurs without long-range memory in the information-theoretical sense. We find that the mutual information function of neurophysiological data behaves differently from fractional Gaussian noise (fGn), for which the Hurst phenomenon is a sufficient condition to prove long-range memory. Two other well-characterized, short-range correlated stochastic processes (Ornstein-Uhlenbeck, Cox-Ingersoll-Ross) also yield H >0.5 , whereas their mutual information functions lie within the Markovian confidence intervals, similar to neural signals. In these processes, which do not have long-range memory by construction, a spurious Hurst phenomenon occurs due to slow relaxation times and heteroscedasticity (time-varying conditional variance). In summary, we find that mutual information correctly distinguishes long-range from short-range dependence in the theoretical and experimental cases discussed. Our results also suggest that the stationary fGn process is not sufficient to describe neural data, which

Response Function of the Crayfish Caudal Photoreceptor to Hydrodynamic Stimuli

Science.gov (United States)

Breite, Sally; Bahar, Sonya; Neiman, Alexander; Moss, Frank

2002-03-01

In its abdominal 6th ganglion the crayfish houses 2 light-sensitive neurons (caudal photoreceptors, or CPRs). It is known that these neurons work in tandem with a mechanosensory system of tiny hairs spread across the tailfan, which make synaptic contact with the photoreceptors. A stochastic resonance effect has been shown in this system in which light enhances the transduction of a weak, periodic mechanosensory (hydrodynamic) stimulus. It is not known, however, whether an optimal response from the CPR is induced by a single sine wave cycle or some other waveform. We have experimentally investigated this favorable waveform by driving a tailfan preparation with mechanical 10 Hz correlated Ornstein-Uhlenbeck noise and calculating the response function from the spike-triggered average of the applied noise waveform. We will discuss differences in the shape of the optimal waveform under dark and light conditions, as well as what seems to be a noticeable difference in the magnitude of the animals' response to a noisy stimulus in comparison with a periodic stimulus.

Framework based on communicability and flow to analyze complex network dynamics

Science.gov (United States)

Gilson, M.; Kouvaris, N. E.; Deco, G.; Zamora-López, G.

2018-05-01

Graph theory constitutes a widely used and established field providing powerful tools for the characterization of complex networks. The intricate topology of networks can also be investigated by means of the collective dynamics observed in the interactions of self-sustained oscillations (synchronization patterns) or propagationlike processes such as random walks. However, networks are often inferred from real-data-forming dynamic systems, which are different from those employed to reveal their topological characteristics. This stresses the necessity for a theoretical framework dedicated to the mutual relationship between the structure and dynamics in complex networks, as the two sides of the same coin. Here we propose a rigorous framework based on the network response over time (i.e., Green function) to study interactions between nodes across time. For this purpose we define the flow that describes the interplay between the network connectivity and external inputs. This multivariate measure relates to the concepts of graph communicability and the map equation. We illustrate our theory using the multivariate Ornstein-Uhlenbeck process, which describes stable and non-conservative dynamics, but the formalism can be adapted to other local dynamics for which the Green function is known. We provide applications to classical network examples, such as small-world ring and hierarchical networks. Our theory defines a comprehensive framework that is canonically related to directed and weighted networks, thus paving a way to revise the standards for network analysis, from the pairwise interactions between nodes to the global properties of networks including community detection.

Thermodynamics and relativistic kinetic theory for q-generalized Bose-Einstein and Fermi-Dirac systems

Science.gov (United States)

Mitra, Sukanya

2018-01-01

The thermodynamics and covariant kinetic theory are elaborately investigated in a non-extensive environment considering the non-extensive generalization of Bose-Einstein (BE) and Fermi-Dirac (FD) statistics. Starting with Tsallis' entropy formula, the fundamental principles of thermostatistics are established for a grand canonical system having q-generalized BE/FD degrees of freedom. Many particle kinetic theory is set up in terms of the relativistic transport equation with q-generalized Uehling-Uhlenbeck collision term. The conservation laws are realized in terms of appropriate moments of the transport equation. The thermodynamic quantities are obtained in a weak non-extensive environment for a massive pion-nucleon and a massless quark-gluon system with non-zero baryon chemical potential. In order to get an estimate of the impact of non-extensivity on the system dynamics, the q-modified Debye mass and hence the q-modified effective coupling are estimated for a quark-gluon system.

Stochastic modeling of the Fermi/LAT γ-ray blazar variability

Energy Technology Data Exchange (ETDEWEB)

Sobolewska, M. A.; Siemiginowska, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kelly, B. C. [Department of Physics, Broida Hall, University of California, Santa Barbara, CA 93107 (United States); Nalewajko, K., E-mail: malgosia@camk.edu.pl [JILA, University of Colorado and National Institute of Standards and Technology, 440 UCB, Boulder, CO 80309 (United States)

2014-05-10

We study the γ-ray variability of 13 blazars observed with the Fermi/Large Area Telescope (LAT). These blazars have the most complete light curves collected during the first four years of the Fermi sky survey. We model them with the Ornstein-Uhlenbeck (OU) process or a mixture of the OU processes. The OU process has power spectral density (PSD) proportional to 1/f {sup α} with α changing at a characteristic timescale, τ{sub 0}, from 0 (τ >> τ{sub 0}) to 2 (τ << τ{sub 0}). The PSD of the mixed OU process has two characteristic timescales and an additional intermediate region with 0 < α < 2. We show that the OU model provides a good description of the Fermi/LAT light curves of three blazars in our sample. For the first time, we constrain a characteristic γ-ray timescale of variability in two BL Lac sources, 3C 66A and PKS 2155-304 (τ{sub 0} ≅ 25 days and τ{sub 0} ≅ 43 days, respectively, in the observer's frame), which are longer than the soft X-ray timescales detected in blazars and Seyfert galaxies. We find that the mixed OU process approximates the light curves of the remaining 10 blazars better than the OU process. We derive limits on their long and short characteristic timescales, and infer that their Fermi/LAT PSD resemble power-law functions. We constrain the PSD slopes for all but one source in the sample. We find hints for sub-hour Fermi/LAT variability in four flat spectrum radio quasars. We discuss the implications of our results for theoretical models of blazar variability.

Phylogenetic correlograms and the evolution of body size in South American owls (Strigiformes

Directory of Open Access Journals (Sweden)

José Alexandre Felizola Diniz-Filho

2000-06-01

Full Text Available During the last few years, many models have been proposed to link microevolutionary processes to macroevolutionary patterns, defined by comparative data analysis. Among these, Brownian motion and Ornstein-Uhlenbeck (O-U processes have been used to model, respectively, genetic drift or directional selection and stabilizing selection. These models produce different curves of pairwise variance between species against time since divergence, in such a way that different profiles appear in phylogenetic correlograms. We analyzed variation in body length among 19 species of South American owls, by means of phylogenetic correlograms constructed using Moran's I coefficient in four distance classes. Phylogeny among species was based on DNA hybridization. The observed correlogram was then compared with 500 correlograms obtained by simulations of Brownian motion and O-U over the same phylogeny, using discriminant analysis. The observed correlogram indicates a phylogenetic gradient up to 45 mya, when coefficients tend to stabilize, and it is similar to the correlograms produced by the O-U process. This is expected when we consider that body size of organisms is correlated with many ecological and life-history traits and subjected to many constraints that can be modeled by the O-U process, which has been used to describe evolution under stabilizing selection.Nos últimos anos diversos modelos têm sido propostos a fim de realizar inferências sobre processos microevolutivos com base em padrões macroevolutivos obtidos a partir de dados comparativos. Dentre esses, o movimento Browniano e o processo Ornstein-Uhlenbeck (O-U têm sido utilizados para modelar principalmente deriva genética e seleção estabilizadora, respectivamente. Esses modelos produzem curvas diferentes de relação entre variância interespecífica e distância no tempo, de modo que eles podem ser distingüidos com base em correlogramas filogenéticos. Neste trabalho, nós analisamos a varia

Thermodynamics and relativistic kinetic theory for q-generalized Bose-Einstein and Fermi-Dirac systems

Energy Technology Data Exchange (ETDEWEB)

Mitra, Sukanya [Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat (India)

2018-01-15

The thermodynamics and covariant kinetic theory are elaborately investigated in a non-extensive environment considering the non-extensive generalization of Bose-Einstein (BE) and Fermi-Dirac (FD) statistics. Starting with Tsallis' entropy formula, the fundamental principles of thermostatistics are established for a grand canonical system having q-generalized BE/FD degrees of freedom. Many particle kinetic theory is set up in terms of the relativistic transport equation with q-generalized Uehling-Uhlenbeck collision term. The conservation laws are realized in terms of appropriate moments of the transport equation. The thermodynamic quantities are obtained in a weak non-extensive environment for a massive pion-nucleon and a massless quark-gluon system with non-zero baryon chemical potential. In order to get an estimate of the impact of non-extensivity on the system dynamics, the q-modified Debye mass and hence the q-modified effective coupling are estimated for a quark-gluon system. (orig.)

From correlation to causation: Estimating effective connectivity from zero-lag covariances of brain signals.

Science.gov (United States)

Schiefer, Jonathan; Niederbühl, Alexander; Pernice, Volker; Lennartz, Carolin; Hennig, Jürgen; LeVan, Pierre; Rotter, Stefan

2018-03-01

Knowing brain connectivity is of great importance both in basic research and for clinical applications. We are proposing a method to infer directed connectivity from zero-lag covariances of neuronal activity recorded at multiple sites. This allows us to identify causal relations that are reflected in neuronal population activity. To derive our strategy, we assume a generic linear model of interacting continuous variables, the components of which represent the activity of local neuronal populations. The suggested method for inferring connectivity from recorded signals exploits the fact that the covariance matrix derived from the observed activity contains information about the existence, the direction and the sign of connections. Assuming a sparsely coupled network, we disambiguate the underlying causal structure via L1-minimization, which is known to prefer sparse solutions. In general, this method is suited to infer effective connectivity from resting state data of various types. We show that our method is applicable over a broad range of structural parameters regarding network size and connection probability of the network. We also explored parameters affecting its activity dynamics, like the eigenvalue spectrum. Also, based on the simulation of suitable Ornstein-Uhlenbeck processes to model BOLD dynamics, we show that with our method it is possible to estimate directed connectivity from zero-lag covariances derived from such signals. In this study, we consider measurement noise and unobserved nodes as additional confounding factors. Furthermore, we investigate the amount of data required for a reliable estimate. Additionally, we apply the proposed method on full-brain resting-state fast fMRI datasets. The resulting network exhibits a tendency for close-by areas being connected as well as inter-hemispheric connections between corresponding areas. In addition, we found that a surprisingly large fraction of more than one third of all identified connections were of

On the degree distribution of horizontal visibility graphs associated with Markov processes and dynamical systems: diagrammatic and variational approaches

International Nuclear Information System (INIS)

Lacasa, Lucas

2014-01-01

Dynamical processes can be transformed into graphs through a family of mappings called visibility algorithms, enabling the possibility of (i) making empirical time series analysis and signal processing and (ii) characterizing classes of dynamical systems and stochastic processes using the tools of graph theory. Recent works show that the degree distribution of these graphs encapsulates much information on the signals' variability, and therefore constitutes a fundamental feature for statistical learning purposes. However, exact solutions for the degree distributions are only known in a few cases, such as for uncorrelated random processes. Here we analytically explore these distributions in a list of situations. We present a diagrammatic formalism which computes for all degrees their corresponding probability as a series expansion in a coupling constant which is the number of hidden variables. We offer a constructive solution for general Markovian stochastic processes and deterministic maps. As case tests we focus on Ornstein–Uhlenbeck processes, fully chaotic and quasiperiodic maps. Whereas only for certain degree probabilities can all diagrams be summed exactly, in the general case we show that the perturbation theory converges. In a second part, we make use of a variational technique to predict the complete degree distribution for special classes of Markovian dynamics with fast-decaying correlations. In every case we compare the theory with numerical experiments. (paper)

Contemporary Ecological Interactions Improve Models of Past Trait Evolution.

Science.gov (United States)

Hutchinson, Matthew C; Gaiarsa, Marília P; Stouffer, Daniel B

2018-02-20

Despite the fact that natural selection underlies both traits and interactions, evolutionary models often neglect that ecological interactions may, and in many cases do, influence the evolution of traits. Here, we explore the interdependence of ecological interactions and functional traits in the pollination associations of hawkmoths and flowering plants. Specifically, we develop an adaptation of the Ornstein-Uhlenbeck model of trait evolution that allows us to study the influence of plant corolla depth and observed hawkmoth-plant interactions on the evolution of hawkmoth proboscis length. Across diverse modelling scenarios, we find that the inclusion of contemporary interactions can provide a better description of trait evolution than the null expectation. Moreover, we show that the pollination interactions provide more-likely models of hawkmoth trait evolution when interactions are considered at increasingly finescale groups of hawkmoths. Finally, we demonstrate how the results of best-fit modelling approaches can implicitly support the association between interactions and trait evolution that our method explicitly examines. In showing that contemporary interactions can provide insight into the historical evolution of hawkmoth proboscis length, we demonstrate the clear utility of incorporating additional ecological information to models designed to study past trait evolution.

Decoherence and tripartite entanglement dynamics in the presence of Gaussian and non-Gaussian classical noise

Energy Technology Data Exchange (ETDEWEB)

Kenfack, Lionel Tenemeza, E-mail: kenfacklionel300@gmail.com [Mesoscopic and Multilayer Structure Laboratory, Department of Physics, Faculty of Science, University of Dschang, PO Box: 67 Dschang (Cameroon); Tchoffo, Martin; Fai, Lukong Cornelius [Mesoscopic and Multilayer Structure Laboratory, Department of Physics, Faculty of Science, University of Dschang, PO Box: 67 Dschang (Cameroon); Fouokeng, Georges Collince [Mesoscopic and Multilayer Structure Laboratory, Department of Physics, Faculty of Science, University of Dschang, PO Box: 67 Dschang (Cameroon); Laboratoire de Génie des Matériaux, Pôle Recherche-Innovation-Entrepreneuriat (PRIE), Institut Universitaire de la Côte, BP 3001 Douala (Cameroon)

2017-04-15

We address the entanglement dynamics of a three-qubit system interacting with a classical fluctuating environment described either by a Gaussian or non-Gaussian noise in three different configurations namely: common, independent and mixed environments. Specifically, we focus on the Ornstein-Uhlenbeck (OU) noise and the random telegraph noise (RTN). The qubits are prepared in a state composed of a Greenberger-Horne-Zeilinger (GHZ) and a W state. With the help of the tripartite negativity, we show that the entanglement evolution is not only affected by the type of system-environment coupling but also by the kind and the memory properties of the considered noise. We also compared the dynamics induced by the two kinds of noise and we find that even if both noises have a Lorentzian spectrum, the effects of the OU noise cannot be in a simple way deduced from those of the RTN and vice-versa. In addition, we show that the entanglement can be indefinitely preserved when the qubits are coupled to the environmental noise in a common environment (CE). Finally, the presence or absence of peculiar phenomena such as entanglement revivals (ER) and entanglement sudden death (ESD) is observed.

Decoherence and tripartite entanglement dynamics in the presence of Gaussian and non-Gaussian classical noise

International Nuclear Information System (INIS)

Kenfack, Lionel Tenemeza; Tchoffo, Martin; Fai, Lukong Cornelius; Fouokeng, Georges Collince

2017-01-01

We address the entanglement dynamics of a three-qubit system interacting with a classical fluctuating environment described either by a Gaussian or non-Gaussian noise in three different configurations namely: common, independent and mixed environments. Specifically, we focus on the Ornstein-Uhlenbeck (OU) noise and the random telegraph noise (RTN). The qubits are prepared in a state composed of a Greenberger-Horne-Zeilinger (GHZ) and a W state. With the help of the tripartite negativity, we show that the entanglement evolution is not only affected by the type of system-environment coupling but also by the kind and the memory properties of the considered noise. We also compared the dynamics induced by the two kinds of noise and we find that even if both noises have a Lorentzian spectrum, the effects of the OU noise cannot be in a simple way deduced from those of the RTN and vice-versa. In addition, we show that the entanglement can be indefinitely preserved when the qubits are coupled to the environmental noise in a common environment (CE). Finally, the presence or absence of peculiar phenomena such as entanglement revivals (ER) and entanglement sudden death (ESD) is observed.

Dynamic analysis of trapping and escaping in dual beam optical trap

Science.gov (United States)

Li, Wenqiang; Hu, Huizhu; Su, Heming; Li, Zhenggang; Shen, Yu

2016-10-01

In this paper, we simulate the dynamic movement of a dielectric sphere in optical trap. This dynamic analysis can be used to calibrate optical forces, increase trapping efficiency and measure viscous coefficient of surrounding medium. Since an accurate dynamic analysis is based on a detailed force calculation, we calculate all forces a sphere receives. We get the forces of dual-beam gradient radiation pressure on a micron-sized dielectric sphere in the ray optics regime and utilize Einstein-Ornstein-Uhlenbeck to deal with its Brownian motion forces. Hydrodynamic viscous force also exists when the sphere moves in liquid. Forces from buoyance and gravity are also taken into consideration. Then we simulate trajectory of a sphere when it is subject to all these forces in a dual optical trap. From our dynamic analysis, the sphere can be trapped at an equilibrium point in static water, although it permanently fluctuates around the equilibrium point due to thermal effects. We go a step further to analyze the effects of misalignment of two optical traps. Trapping and escaping phenomena of the sphere in flowing water are also simulated. In flowing water, the sphere is dragged away from the equilibrium point. This dragging distance increases with the decrease of optical power, which results in escaping of the sphere with optical power below a threshold. In both trapping and escaping process we calculate the forces and position of the sphere. Finally, we analyze a trapping region in dual optical tweezers.

LNG as a strategy to establish developing countries' gas markets: The Brazilian case

International Nuclear Information System (INIS)

Alberto Rechelo Neto, Carlos; Sauer, Ildo Luis

2006-01-01

This paper aims to evaluate, from a Brazilian case study, if the natural gas trade can be viewed as a good opportunity for developing countries located geographically close to Western Europe and North America gas markets. Initially, the paper presents an overview of the Brazilian natural gas industry and evaluates the balance between supply and demand in each main region of Brazil. Then, it analyzes the evolution of the international gas trade, which is expected to increase rapidly (LNG particularly). Finally, the paper analyses the financial viability of the Brazilian LNG project in a context of high volatility of natural gas prices in the international market. To take this uncertainty into account, North-American natural gas prices are modelled according to the ORNSTEIN-UHLENBECK process (with EIA data over the period 1985-2003). By using an approach based on Monte-Carlo simulations and under the assumption that imports are guaranteed since the North American gas price would be higher than the breakeven of the Brazilian project, the model aims to test the hypothesis that export can promote the development of the Brazilian Northeastern gas market. LNG project is here compared to the Petrobras pipelines project, which is considered as the immediate solution for the Northeastern gas shortage. As a conclusion, this study shows that the LNG export will be vulnerable to the risks associated to the natural gas prices volatility observed on the international market

Linear response and correlation of a self-propelled particle in the presence of external fields

Science.gov (United States)

Caprini, Lorenzo; Marini Bettolo Marconi, Umberto; Vulpiani, Angelo

2018-03-01

We study the non-equilibrium properties of non interacting active Ornstein-Uhlenbeck particles (AOUP) subject to an external nonuniform field using a Fokker-Planck approach with a focus on the linear response and time-correlation functions. In particular, we compare different methods to compute these functions including the unified colored noise approximation (UCNA). The AOUP model, described by the position of the particle and the active force acting on it, is usually mapped into a Markovian process, describing the motion of a fictitious passive particle in terms of its position and velocity, where the effect of the activity is transferred into a position-dependent friction. We show that the form of the response function of the AOUP depends on whether we put the perturbation on the position and keep unperturbed the active force in the original variables or perturb the position and maintain unperturbed the velocity in the transformed variables. Indeed, as a result of the change of variables the perturbation on the position becomes a perturbation both on the position and on the fictitious velocity. We test these predictions by considering the response for three types of convex potentials: quadratic, quartic and double-well potential. Moreover, by comparing the response of the AOUP model with the corresponding response of the UCNA model we conclude that although the stationary properties are fairly well approximated by the UCNA, the non equilibrium properties are not, an effect which is not negligible when the persistence time is large.

Analysis on one type of swing option in the energy market

International Nuclear Information System (INIS)

Mistry, Hetal A.

2005-01-01

In the Nordic electricity market most of the trading takes place in derivates and options. To describe these products theoretically one needs to have knowledge from stochastic analysis. This thesis will derive a price model for one type of swing option in energy market. The main aim of writing this thesis is to introduce coal power plant and how to approach the problem if such power plant is built in Norway. This thesis uses the approach where I start out with a model for the spot price of electricity and coal, and then derive theoretical option prices. I use a Schwartz process for model and Ornstein Uhlenbeck processes to model the spot prices for electricity and coal. This model also incorporates mean-reversion, which is an important aspect of energy prices. Historical data for the spot prices is used to estimate my variables in the Schwartz model. The main objectives of this thesis were to find the price for a tolling contract in energy market and production volume that is producers control function. The first chapters gives an over view about the agreement and the formula used to derive the price. The second chapter provided me with the material I needed to derive these price and production volume such as dynamics for the spot prices for electricity and coal and their solution. Third chapter gives a statistical look on these stochastic processes. In the last chapter I tested the price model for stochastic control problem and found that the swing option can be bound in two ways: 1. Swing option limited as Margrabes solution. 2. Swing option limited as spread option. The use of the model is discussed. (Author)

The effect of parity on morphological evolution among phrynosomatid lizards.

Science.gov (United States)

Oufiero, C E; Gartner, G E A

2014-11-01

The shift from egg laying to live-bearing is one of the most well-studied transitions in evolutionary biology. Few studies, however, have assessed the effect of this transition on morphological evolution. Here, we evaluated the effect of reproductive mode on the morphological evolution of 10 traits, among 108 species of phrynosomatid lizards. We assess whether the requirement for passing shelled eggs through the pelvic girdle has led to morphological constraints in oviparous species and whether long gestation times in viviparous species have led to constraints in locomotor morphology. We fit models to the data that vary both in their tempo (strength and rate of selection) and mode of evolution (Brownian or Ornstein-Uhlenbeck) and estimates of trait optima. We found that most traits are best fit by a generalized multipeak OU model, suggesting differing trait optima for viviparous vs. oviparous species. Additionally, rates (σ(2) ) of both pelvic girdle and forelimb trait evolution varied with parity; viviparous species had higher rates. Hindlimb traits, however, exhibited no difference in σ(2) between parity modes. In a functional context, our results suggest that the passage of shelled eggs constrains the morphology of the pelvic girdle, but we found no evidence of morphological constraint of the locomotor apparatus in viviparous species. Our results are consistent with recent lineage diversification analyses, leading to the conclusion that transitions to viviparity increase both lineage and morphological diversification. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

A general model for membrane-based separation processes

DEFF Research Database (Denmark)

Soni, Vipasha; Abildskov, Jens; Jonsson, Gunnar Eigil

2009-01-01

behaviour will play an important role. In this paper, modelling of membrane-based processes for separation of gas and liquid mixtures are considered. Two general models, one for membrane-based liquid separation processes (with phase change) and another for membrane-based gas separation are presented....... The separation processes covered are: membrane-based gas separation processes, pervaporation and various types of membrane distillation processes. The specific model for each type of membrane-based process is generated from the two general models by applying the specific system descriptions and the corresponding...

Renewal processes based on generalized Mittag-Leffler waiting times

Science.gov (United States)

Cahoy, Dexter O.; Polito, Federico

2013-03-01

The fractional Poisson process has recently attracted experts from several fields of study. Its natural generalization of the ordinary Poisson process made the model more appealing for real-world applications. In this paper, we generalized the standard and fractional Poisson processes through the waiting time distribution, and showed their relations to an integral operator with a generalized Mittag-Leffler function in the kernel. The waiting times of the proposed renewal processes have the generalized Mittag-Leffler and stretched-squashed Mittag-Leffler distributions. Note that the generalizations naturally provide greater flexibility in modeling real-life renewal processes. Algorithms to simulate sample paths and to estimate the model parameters are derived. Note also that these procedures are necessary to make these models more usable in practice. State probabilities and other qualitative or quantitative features of the models are also discussed.

Nuclear de-excitation processes following medium energy heavy ion collisions

International Nuclear Information System (INIS)

Blann, M.

1986-09-01

As heavy ion reaction studies have progressed from beam energies below 10 MeV/nucleon to higher energies, many non-equilibrium reaction phenomena have been observed. Among these are nucleon emission with velocities in excess of the beam velocity, incomplete momentum transfer to evaporation residue and fission-like fragments, γ-rays with energies in excess of 100 MeV, and π 0 production when beam energies are below the threshold for production by the nucleon-nucleon collision mechanism. Additionally, prefission neutrons have been observed in excess of numbers expected from equilibrium models. A few of the approaches which have been applied to these phenomena are as follows: Intranuclear cascade: two body collisions are assumed to mediate the equilibration. The geometry and momentum space is followed semiclassically. The approach has many successes though it may suffer in a few applications is not following holes; TDHF considers one body processes only; in the energy regime of interest, two body processes are important so that this may not be a viable approach; Boltzmann-Uehling-Uhlenbeck or Vlasov-Uehling-Uhlenbeck (BUU/VUU) equations combine both one body and two body dynamics. The spatial and momentum evolution of the reactions are followed in a mean field. These should be the Cadillacs of the models. They are computationally tedious, and sometimes significant approximations are made in order to achieve computational tract ability; models of collective deceleration. A very simple model approach is discussed to interpret these phenomena, the Boltzmann master equation (BME). The hybrid model was the first to be applied to the question of heavy ion precompound decay, and the BME second. 26 refs., 5 figs., 2 tabs

A Penalized Likelihood Framework For High-Dimensional Phylogenetic Comparative Methods And An Application To New-World Monkeys Brain Evolution.

Science.gov (United States)

Julien, Clavel; Leandro, Aristide; Hélène, Morlon

2018-06-19

Working with high-dimensional phylogenetic comparative datasets is challenging because likelihood-based multivariate methods suffer from low statistical performances as the number of traits p approaches the number of species n and because some computational complications occur when p exceeds n. Alternative phylogenetic comparative methods have recently been proposed to deal with the large p small n scenario but their use and performances are limited. Here we develop a penalized likelihood framework to deal with high-dimensional comparative datasets. We propose various penalizations and methods for selecting the intensity of the penalties. We apply this general framework to the estimation of parameters (the evolutionary trait covariance matrix and parameters of the evolutionary model) and model comparison for the high-dimensional multivariate Brownian (BM), Early-burst (EB), Ornstein-Uhlenbeck (OU) and Pagel's lambda models. We show using simulations that our penalized likelihood approach dramatically improves the estimation of evolutionary trait covariance matrices and model parameters when p approaches n, and allows for their accurate estimation when p equals or exceeds n. In addition, we show that penalized likelihood models can be efficiently compared using Generalized Information Criterion (GIC). We implement these methods, as well as the related estimation of ancestral states and the computation of phylogenetic PCA in the R package RPANDA and mvMORPH. Finally, we illustrate the utility of the new proposed framework by evaluating evolutionary models fit, analyzing integration patterns, and reconstructing evolutionary trajectories for a high-dimensional 3-D dataset of brain shape in the New World monkeys. We find a clear support for an Early-burst model suggesting an early diversification of brain morphology during the ecological radiation of the clade. Penalized likelihood offers an efficient way to deal with high-dimensional multivariate comparative data.

Tendinous framework of anurans reveals an all-purpose morphology.

Science.gov (United States)

Fratani, Jéssica; Ponssa, María Laura; Abdala, Virginia

2018-02-01

Tendons are directly associated with movement, amplifying power and reducing muscular work. Taking into account habitat and locomotor challenges faced by anurans, we identify the more conspicuous superficial tendons of a neotropical anuran group and investigate their relation to the former factors. We show that tendons can be visualized as an anatomical framework connected through muscles and/or fascia, and describe the most superficial tendinous layer of the postcranium of Leptodactylus latinasus. To analyze the relation between tendon morphology and ecological characters, we test the relative length ratio of 10 tendon-muscle (t-m) elements in 45 leptodactylid species while taking phylogeny into account. We identify the evolutionary model that best explains our variables. Additionally, we optimize t-m ratio values, and the shape of the longissimus dorsi insertion onto a selected phylogeny of the species. Our data show the existence of an all-purpose morphology that seems to have evolved independently of ecology and functional requirements. This is indicated by no significant relation between morphometric data of the analyzed tendons and habitat use or locomotion, a strong phylogenetic component to most of the analyzed variables, and a generalized pattern of intermediate values for ancestral states. Ornstein-Uhlenbeck is the model that best explains most t-m variables, indicating that stabilizing selection or selective optima might be driving shifts in tendon length within Leptodactylidae. Herein, we show the substantial influence that phylogeny has on tendon morphology, demonstrating that a generalized and stable morphological configuration of tendons is adequate to enable versatile locomotor modes and habitat use. This is an attempt to present the tendinous system as a framework to body support in vertebrates, and can be considered a starting point for further ecomorphological research of this anatomical system in anurans. Copyright © 2017 Elsevier GmbH. All

Important contributions of M.C. Wang and C.S. Wang Chang to non-equilibrium statistical physics

International Nuclear Information System (INIS)

Liu Jixing

2004-01-01

In the middle of the 20th century two Chinese women physicists, Ming-Chen Wang and Cheng-Shu Wang Chang made great contributions to statistical physics. The famous review article 'On the theory of the Brownian motion II' by Ming-Chen Wang and G.E. Uhlenbeck published in Rev. of Mod. Phys. in 1945 provided a complete scientific classification of stochastic processes which is still adopted by the scientific community as the standard classification. The Wang-Chang-Uhlenbeck (WCU) equation proposed jointly by C.S. Wang-Chang and Uhlenbeck became the fundamental kinetic equation for the treatment of transport properties of multi-atomic gases with internal degrees of freedom in the physics literature. These important scientific contributions are analyzed and reviewed

Real-time radar signal processing using GPGPU (general-purpose graphic processing unit)

Science.gov (United States)

Kong, Fanxing; Zhang, Yan Rockee; Cai, Jingxiao; Palmer, Robert D.

2016-05-01

This study introduces a practical approach to develop real-time signal processing chain for general phased array radar on NVIDIA GPUs(Graphical Processing Units) using CUDA (Compute Unified Device Architecture) libraries such as cuBlas and cuFFT, which are adopted from open source libraries and optimized for the NVIDIA GPUs. The processed results are rigorously verified against those from the CPUs. Performance benchmarked in computation time with various input data cube sizes are compared across GPUs and CPUs. Through the analysis, it will be demonstrated that GPGPUs (General Purpose GPU) real-time processing of the array radar data is possible with relatively low-cost commercial GPUs.

Melnikov processes and chaos in randomly perturbed dynamical systems

Science.gov (United States)

Yagasaki, Kazuyuki

2018-07-01

We consider a wide class of randomly perturbed systems subjected to stationary Gaussian processes and show that chaotic orbits exist almost surely under some nondegenerate condition, no matter how small the random forcing terms are. This result is very contrasting to the deterministic forcing case, in which chaotic orbits exist only if the influence of the forcing terms overcomes that of the other terms in the perturbations. To obtain the result, we extend Melnikov’s method and prove that the corresponding Melnikov functions, which we call the Melnikov processes, have infinitely many zeros, so that infinitely many transverse homoclinic orbits exist. In addition, a theorem on the existence and smoothness of stable and unstable manifolds is given and the Smale–Birkhoff homoclinic theorem is extended in an appropriate form for randomly perturbed systems. We illustrate our theory for the Duffing oscillator subjected to the Ornstein–Uhlenbeck process parametrically.

Quantum thermodynamics of general quantum processes.

Science.gov (United States)

Binder, Felix; Vinjanampathy, Sai; Modi, Kavan; Goold, John

2015-03-01

Accurately describing work extraction from a quantum system is a central objective for the extension of thermodynamics to individual quantum systems. The concepts of work and heat are surprisingly subtle when generalizations are made to arbitrary quantum states. We formulate an operational thermodynamics suitable for application to an open quantum system undergoing quantum evolution under a general quantum process by which we mean a completely positive and trace-preserving map. We derive an operational first law of thermodynamics for such processes and show consistency with the second law. We show that heat, from the first law, is positive when the input state of the map majorizes the output state. Moreover, the change in entropy is also positive for the same majorization condition. This makes a strong connection between the two operational laws of thermodynamics.

The tempo and mode of evolution: body sizes of island mammals.

Science.gov (United States)

Raia, Pasquale; Meiri, Shai

2011-07-01

The tempo and mode of body size evolution on islands are believed to be well known. It is thought that body size evolves relatively quickly on islands toward the mammalian modal value, thus generating extreme cases of size evolution and the island rule. Here, we tested both theories in a phylogenetically explicit context, by using two different species-level mammalian phylogenetic hypotheses limited to sister clades dichotomizing into an exclusively insular and an exclusively mainland daughter nodes. Taken as a whole, mammals were found to show a largely punctuational mode of size evolution. We found that, accounting for this, and regardless of the phylogeny used, size evolution on islands is no faster than on the continents. We compared different selection regimes using a set of Ornstein-Uhlenbeck models to examine the effects of insularity of the mode of evolution. The models strongly supported clade-specific selection regimes. Under this regime, however, an evolutionary model allowing insular species to evolve differently from their mainland relatives performs worse than a model that ignores insularity as a factor. Thus, insular taxa do not experience statistically different selection from their mainland relatives. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

Confined active Brownian particles: theoretical description of propulsion-induced accumulation

Science.gov (United States)

Das, Shibananda; Gompper, Gerhard; Winkler, Roland G.

2018-01-01

The stationary-state distribution function of confined active Brownian particles (ABPs) is analyzed by computer simulations and analytical calculations. We consider a radial harmonic as well as an anharmonic confinement potential. In the simulations, the ABP is propelled with a prescribed velocity along a body-fixed direction, which is changing in a diffusive manner. For the analytical approach, the Cartesian components of the propulsion velocity are assumed to change independently; active Ornstein-Uhlenbeck particle (AOUP). This results in very different velocity distribution functions. The analytical solution of the Fokker-Planck equation for an AOUP in a harmonic potential is presented and a conditional distribution function is provided for the radial particle distribution at a given magnitude of the propulsion velocity. This conditional probability distribution facilitates the description of the coupling of the spatial coordinate and propulsion, which yields activity-induced accumulation of particles. For the anharmonic potential, a probability distribution function is derived within the unified colored noise approximation. The comparison of the simulation results with theoretical predictions yields good agreement for large rotational diffusion coefficients, e.g. due to tumbling, even for large propulsion velocities (Péclet numbers). However, we find significant deviations already for moderate Péclet number, when the rotational diffusion coefficient is on the order of the thermal one.

Quantifying the value of investing in distributed natural gas and renewable electricity systems as complements: Applications of discounted cash flow and real options analysis with stochastic inputs

International Nuclear Information System (INIS)

Pless, Jacquelyn; Arent, Douglas J.; Logan, Jeffrey; Cochran, Jaquelin; Zinaman, Owen

2016-01-01

One energy policy objective in the United States is to promote the adoption of technologies that provide consumers with stable, secure, and clean energy. Recent work provides anecdotal evidence of natural gas (NG) and renewable electricity (RE) synergies in the power sector, however few studies quantify the value of investing in NG and RE systems together as complements. This paper uses discounted cash flow analysis and real options analysis to value hybrid NG-RE systems in distributed applications, focusing on residential and commercial projects assumed to be located in the states of New York and Texas. Technology performance and operational risk profiles are modeled at the hourly level to capture variable RE output and NG prices are modeled stochastically as geometric Ornstein-Uhlenbeck (OU) stochastic processes to capture NG price uncertainty. The findings consistently suggest that NG-RE hybrid distributed systems are more favorable investments in the applications studied relative to their single-technology alternatives when incentives for renewables are available. In some cases, NG-only systems are the favorable investments. Understanding the value of investing in NG-RE hybrid systems provides insights into one avenue towards reducing greenhouse gas emissions, given the important role of NG and RE in the power sector. - Highlights: • Natural gas and renewable electricity can be viewed as complements. • We model hybrid natural gas and renewable electricity systems at the hourly level. • We incorporate variable renewable power output and uncertain natural gas prices. • Hybrid natural gas and renewable electricity systems can be valuable investments.

20 CFR 405.701 - Expedited appeals process-general.

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Expedited appeals process-general. 405.701 Section 405.701 Employees' Benefits SOCIAL SECURITY ADMINISTRATION ADMINISTRATIVE REVIEW PROCESS FOR ADJUDICATING INITIAL DISABILITY CLAIMS Expedited Appeals Process for Constitutional Issues § 405.701 Expedited...

OVPD-processed OLED for general lighting

OpenAIRE

Bösing, Manuel

2012-01-01

Due to continuous advancements of materials for organic light emitting diodes (OLED) a new field of application currently opens up for OLED technology: General lighting. A significant reduction of OLED production cost might be achieved by employing organic vapor phase deposition (OVPD). OVPD is a novel process for depositing organic thin films from the gas phase. In contrast to the well established process of vacuum thermal evaporation (VTE), OVPD allows to achieve much higher deposition rate...

Class Counts: An Overview and Response to Mr. Cooper's Review

Science.gov (United States)

Ornstein, Allan

2009-01-01

This article presents Allan Ornstein's response to highly respected scholar, Bruce Cooper's review of Ornstein's 2007 book, "Class Counts: Education, Inequality and the Shrinking Middle Class." Here Ornstein attempts to elaborate on a few points that he felt Cooper missed in his review.

Learning Theory Estimates with Observations from General Stationary Stochastic Processes.

Science.gov (United States)

Hang, Hanyuan; Feng, Yunlong; Steinwart, Ingo; Suykens, Johan A K

2016-12-01

This letter investigates the supervised learning problem with observations drawn from certain general stationary stochastic processes. Here by general, we mean that many stationary stochastic processes can be included. We show that when the stochastic processes satisfy a generalized Bernstein-type inequality, a unified treatment on analyzing the learning schemes with various mixing processes can be conducted and a sharp oracle inequality for generic regularized empirical risk minimization schemes can be established. The obtained oracle inequality is then applied to derive convergence rates for several learning schemes such as empirical risk minimization (ERM), least squares support vector machines (LS-SVMs) using given generic kernels, and SVMs using gaussian kernels for both least squares and quantile regression. It turns out that for independent and identically distributed (i.i.d.) processes, our learning rates for ERM recover the optimal rates. For non-i.i.d. processes, including geometrically [Formula: see text]-mixing Markov processes, geometrically [Formula: see text]-mixing processes with restricted decay, [Formula: see text]-mixing processes, and (time-reversed) geometrically [Formula: see text]-mixing processes, our learning rates for SVMs with gaussian kernels match, up to some arbitrarily small extra term in the exponent, the optimal rates. For the remaining cases, our rates are at least close to the optimal rates. As a by-product, the assumed generalized Bernstein-type inequality also provides an interpretation of the so-called effective number of observations for various mixing processes.

Parameter-free resolution of the superposition of stochastic signals

Energy Technology Data Exchange (ETDEWEB)

Scholz, Teresa, E-mail: tascholz@fc.ul.pt [Center for Theoretical and Computational Physics, University of Lisbon (Portugal); Raischel, Frank [Center for Geophysics, IDL, University of Lisbon (Portugal); Closer Consulting, Av. Eng. Duarte Pacheco Torre 1 15" 0, 1070-101 Lisboa (Portugal); Lopes, Vitor V. [DEIO-CIO, University of Lisbon (Portugal); UTEC–Universidad de Ingeniería y Tecnología, Lima (Peru); Lehle, Bernd; Wächter, Matthias; Peinke, Joachim [Institute of Physics and ForWind, Carl-von-Ossietzky University of Oldenburg, Oldenburg (Germany); Lind, Pedro G. [Institute of Physics and ForWind, Carl-von-Ossietzky University of Oldenburg, Oldenburg (Germany); Institute of Physics, University of Osnabrück, Osnabrück (Germany)

2017-01-30

This paper presents a direct method to obtain the deterministic and stochastic contribution of the sum of two independent stochastic processes, one of which is an Ornstein–Uhlenbeck process and the other a general (non-linear) Langevin process. The method is able to distinguish between the stochastic processes, retrieving their corresponding stochastic evolution equations. This framework is based on a recent approach for the analysis of multidimensional Langevin-type stochastic processes in the presence of strong measurement (or observational) noise, which is here extended to impose neither constraints nor parameters and extract all coefficients directly from the empirical data sets. Using synthetic data, it is shown that the method yields satisfactory results.

Studying the evolutionary significance of thermal adaptation in ectotherms: The diversification of amphibians' energetics.

Science.gov (United States)

Nespolo, Roberto F; Figueroa, Julio; Solano-Iguaran, Jaiber J

2017-08-01

A fundamental problem in evolutionary biology is the understanding of the factors that promote or constrain adaptive evolution, and assessing the role of natural selection in this process. Here, comparative phylogenetics, that is, using phylogenetic information and traits to infer evolutionary processes has been a major paradigm . In this study, we discuss Ornstein-Uhlenbeck models (OU) in the context of thermal adaptation in ectotherms. We specifically applied this approach to study amphibians's evolution and energy metabolism. It has been hypothesized that amphibians exploit adaptive zones characterized by low energy expenditure, which generate specific predictions in terms of the patterns of diversification in standard metabolic rate (SMR). We complied whole-animal metabolic rates for 122 species of amphibians, and adjusted several models of diversification. According to the adaptive zone hypothesis, we expected: (1) to find "accelerated evolution" in SMR (i.e., diversification above Brownian Motion expectations, BM), (2) that a model assuming evolutionary optima (i.e., an OU model) fits better than a white-noise model and (3) that a model assuming multiple optima (according to the three amphibians's orders) fits better than a model assuming a single optimum. As predicted, we found that the diversification of SMR occurred most of the time, above BM expectations. Also, we found that a model assuming an optimum explained the data in a better way than a white-noise model. However, we did not find evidence that an OU model with multiple optima fits the data better, suggesting a single optimum in SMR for Anura, Caudata and Gymnophiona. These results show how comparative phylogenetics could be applied for testing adaptive hypotheses regarding history and physiological performance in ectotherms. Copyright © 2016 Elsevier Ltd. All rights reserved.

Noise suppression via generalized-Markovian processes

Science.gov (United States)

Marshall, Jeffrey; Campos Venuti, Lorenzo; Zanardi, Paolo

2017-11-01

It is by now well established that noise itself can be useful for performing quantum information processing tasks. We present results which show how one can effectively reduce the error rate associated with a noisy quantum channel by counteracting its detrimental effects with another form of noise. In particular, we consider the effect of adding on top of a purely Markovian (Lindblad) dynamics, a more general form of dissipation, which we refer to as generalized-Markovian noise. This noise has an associated memory kernel and the resulting dynamics are described by an integrodifferential equation. The overall dynamics are characterized by decay rates which depend not only on the original dissipative time scales but also on the new integral kernel. We find that one can engineer this kernel such that the overall rate of decay is lowered by the addition of this noise term. We illustrate this technique for the case where the bare noise is described by a dephasing Pauli channel. We analytically solve this model and show that one can effectively double (or even triple) the length of the channel, while achieving the same fidelity, entanglement, and error threshold. We numerically verify this scheme can also be used to protect against thermal Markovian noise (at nonzero temperature), which models spontaneous emission and excitation processes. A physical interpretation of this scheme is discussed, whereby the added generalized-Markovian noise causes the system to become periodically decoupled from the background Markovian noise.

MOTRIMS as a generalized probe of AMO processes

International Nuclear Information System (INIS)

Bredy, R.; Nguyen, H.; Camp, H.; Flechard, X.; De Paola, B.D.

2003-01-01

Magneto-optical trap recoil ion momentum spectroscopy (MOTRIMS) is one of the newest offshoots of the generalized TRIMS approach to ion-atom collisions. By using lasers instead of the more usual supersonic expansion to cool the target, MOTRIMS has demonstrated two distinct advantages over conventional TRIMS. The first is better resolution, now limited by detectors instead of target temperature. The second is its suitability for use in the study of laser-excited targets. In this presentation we will present a third advantage: The use of MOTRIMS as a general-purpose probe of AMO processes in cold atomic clouds of atoms and molecules. Specifically, the projectile ion beam can be used as a probe of processes as diverse as target dressing by femtosecond optical pulses, photo-association (laser-assisted cold collisions) photo-ionization, and electromagnetically-induced transparency. We will present data for the processes we have investigated, and speculations on what we expect to see for the processes we plan to investigate in the future

Integer valued autoregressive processes with generalized discrete Mittag-Leffler marginals

Directory of Open Access Journals (Sweden)

Kanichukattu K. Jose

2013-05-01

Full Text Available In this paper we consider a generalization of discrete Mittag-Leffler distributions. We introduce and study the properties of a new distribution called geometric generalized discrete Mittag-Leffler distribution. Autoregressive processes with geometric generalized discrete Mittag-Leffler distributions are developed and studied. The distributions are further extended to develop a more general class of geometric generalized discrete semi-Mittag-Leffler distributions. The processes are extended to higher orders also. An application with respect to an empirical data on customer arrivals in a bank counter is also given. Various areas of potential applications like human resource development, insect growth, epidemic modeling, industrial risk modeling, insurance and actuaries, town planning etc are also discussed.

General Notes on Processes and Their Spectra

Directory of Open Access Journals (Sweden)

Gustav Cepciansky

2012-01-01

Full Text Available The frequency spectrum performs one of the main characteristics of a process. The aim of the paper is to show the coherence between the process and its own spectrum and how the behaviour and properties of a process itself can be deduced from its spectrum. Processes are categorized and general principles of their spectra calculation and recognition are given. The main stress is put on power spectra of electric and optic signals, as they also perform a kind of processes. These spectra can be directly measured, observed and examined by means of spectral analyzers and they are very important characteristics which can not be omitted at transmission techniques in telecommunication technologies. Further, the paper also deals with non electric processes, mainly with processes and spectra at mass servicing and how these spectra can be utilised in praxis.

A generalized integral fluctuation theorem for general jump processes

International Nuclear Information System (INIS)

Liu Fei; Ouyang Zhongcan; Luo Yupin; Huang Mingchang

2009-01-01

Using the Feynman-Kac and Cameron-Martin-Girsanov formulae, we obtain a generalized integral fluctuation theorem (GIFT) for discrete jump processes by constructing a time-invariable inner product. The existing discrete IFTs can be derived as its specific cases. A connection between our approach and the conventional time-reversal method is also established. Unlike the latter approach that has been extensively employed in the existing literature, our approach can naturally bring out the definition of a time reversal of a Markovian stochastic system. Additionally, we find that the robust GIFT usually does not result in a detailed fluctuation theorem. (fast track communication)

Ecological and phylogenetic variability in the spinalis muscle of snakes.

Science.gov (United States)

Tingle, J L; Gartner, G E A; Jayne, B C; Garland, T

2017-11-01

Understanding the origin and maintenance of functionally important subordinate traits is a major goal of evolutionary physiologists and ecomorphologists. Within the confines of a limbless body plan, snakes are diverse in terms of body size and ecology, but we know little about the functional traits that underlie this diversity. We used a phylogenetically diverse group of 131 snake species to examine associations between habitat use, sidewinding locomotion and constriction behaviour with the number of body vertebrae spanned by a single segment of the spinalis muscle, with total numbers of body vertebrae used as a covariate in statistical analyses. We compared models with combinations of these predictors to determine which best fit the data among all species and for the advanced snakes only (N = 114). We used both ordinary least-squares models and phylogenetic models in which the residuals were modelled as evolving by the Ornstein-Uhlenbeck process. Snakes with greater numbers of vertebrae tended to have spinalis muscles that spanned more vertebrae. Habitat effects dominated models for analyses of all species and advanced snakes only, with the spinalis length spanning more vertebrae in arboreal species and fewer vertebrae in aquatic and burrowing species. Sidewinding specialists had shorter muscle lengths than nonspecialists. The relationship between prey constriction and spinalis length was less clear. Differences among clades were also strong when considering all species, but not for advanced snakes alone. Overall, these results suggest that muscle morphology may have played a key role in the adaptive radiation of snakes. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Statistics of zero crossings in rough interfaces with fractional elasticity

Science.gov (United States)

Zamorategui, Arturo L.; Lecomte, Vivien; Kolton, Alejandro B.

2018-04-01

We study numerically the distribution of zero crossings in one-dimensional elastic interfaces described by an overdamped Langevin dynamics with periodic boundary conditions. We model the elastic forces with a Riesz-Feller fractional Laplacian of order z =1 +2 ζ , such that the interfaces spontaneously relax, with a dynamical exponent z , to a self-affine geometry with roughness exponent ζ . By continuously increasing from ζ =-1 /2 (macroscopically flat interface described by independent Ornstein-Uhlenbeck processes [Phys. Rev. 36, 823 (1930), 10.1103/PhysRev.36.823]) to ζ =3 /2 (super-rough Mullins-Herring interface), three different regimes are identified: (I) -1 /2 value in the system size, or decays as a power-law towards (II) a subextensive or (III) an intensive value. In the steady state, the distribution of intervals between zeros changes from an exponential decay in (I) to a power-law decay P (ℓ ) ˜ℓ-γ in (II) and (III). While in (II) γ =1 -θ with θ =1 -ζ the steady-state persistence exponent, in (III) we obtain γ =3 -2 ζ , different from the exponent γ =1 expected from the prediction θ =0 for infinite super-rough interfaces with ζ >1 . The effect on P (ℓ ) of short-scale smoothening is also analyzed numerically and analytically. A tight relation between the mean interval, the mean width of the interface, and the density of zeros is also reported. The results drawn from our analysis of rough interfaces subject to particular boundary conditions or constraints, along with discretization effects, are relevant for the practical analysis of zeros in interface imaging experiments or in numerical analysis.

Is the number and size of scales in Liolaemus lizards driven by climate?

Science.gov (United States)

José Tulli, María; Cruz, Félix B

2018-05-03

Ectothermic vertebrates are sensitive to thermal fluctuations in the environments where they occur. To buffer these fluctuations, ectotherms use different strategies, including the integument, which is a barrier that minimizes temperature exchange between the inner body and the surrounding air. In lizards, this barrier is constituted by keratinized scales of variable size, shape and texture, and its main function is protection, water loss avoidance and thermoregulation. The size of scales in lizards has been proposed to vary in relation to climatic gradients; however, it has also been observed that in some groups of Iguanian lizards could be related to phylogeny. Thus, here, we studied the area and number of scales (dorsal and ventral) of 61 species of Liolaemus lizards distributed in a broad latitudinal and altitudinal gradient to determine the nature of the variation of the scales with climate, and found that the number and size of scales are related to climatic variables, such as temperature and geographical variables as altitude. The evolutionary process that better explained how these morphological variables evolved was the Ornstein-Uhlenbeck model. The number of scales seemed to be related to common ancestry, whereas dorsal and ventral scale areas seemed to vary as a consequence of ecological traits. In fact, the ventral area is less exposed to climate conditions such as ultraviolet radiation or wind and is thus under less pressure to change in response to alterations in external conditions. It is possible that scale ornamentation such as keels and granulosity may bring some more information in this regard. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Phylogeny, ecology, and heart position in snakes.

Science.gov (United States)

Gartner, Gabriel E A; Hicks, James W; Manzani, Paulo R; Andrade, Denis V; Abe, Augusto S; Wang, Tobias; Secor, Stephen M; Garland, Theodore

2010-01-01

The cardiovascular system of all animals is affected by gravitational pressure gradients, the intensity of which varies according to organismic features, behavior, and habitat occupied. A previous nonphylogenetic analysis of heart position in snakes-which often assume vertical postures-found the heart located 15%-25% of total body length from the head in terrestrial and arboreal species but 25%-45% in aquatic species. It was hypothesized that a more anterior heart in arboreal species served to reduce the hydrostatic blood pressure when these animals adopt vertical postures during climbing, whereas an anterior heart position would not be needed in aquatic habitats, where the effects of gravity are less pronounced. We analyzed a new data set of 155 species from five major families of Alethinophidia (one of the two major branches of snakes, the other being blind snakes, Scolecophidia) using both conventional and phylogenetically based statistical methods. General linear models regressing log(10) snout-heart position on log(10) snout-vent length (SVL), as well as dummy variables coding for habitat and/or clade, were compared using likelihood ratio tests and the Akaike Information Criterion. Heart distance to the tip of the snout scaled isometrically with SVL. In all instances, phylogenetic models that incorporated transformation of the branch lengths under an Ornstein-Uhlenbeck model of evolution (to mimic stabilizing selection) better fit the data as compared with their nonphylogenetic counterparts. The best-fit model predicting snake heart position included aspects of both habitat and clade and indicated that arboreal snakes in our study tend to have hearts placed more posteriorly, opposite the trend identified in previous studies. Phylogenetic signal in relative heart position was apparent both within and among clades. Our results suggest that overcoming gravitational pressure gradients in snakes most likely involves the combined action of several cardiovascular and

Visual Processing in Generally Gifted and Mathematically Excelling Adolescents

Science.gov (United States)

Paz-Baruch, Nurit; Leikin, Roza; Leikin, Mark

2016-01-01

Little empirical data are available concerning the cognitive abilities of gifted individuals in general and especially those who excel in mathematics. We examined visual processing abilities distinguishing between general giftedness (G) and excellence in mathematics (EM). The research population consisted of 190 students from four groups of 10th-…

A general software reliability process simulation technique

Science.gov (United States)

Tausworthe, Robert C.

1991-01-01

The structure and rationale of the generalized software reliability process, together with the design and implementation of a computer program that simulates this process are described. Given assumed parameters of a particular project, the users of this program are able to generate simulated status timelines of work products, numbers of injected anomalies, and the progress of testing, fault isolation, repair, validation, and retest. Such timelines are useful in comparison with actual timeline data, for validating the project input parameters, and for providing data for researchers in reliability prediction modeling.

General simulation algorithm for autocorrelated binary processes.

Science.gov (United States)

Serinaldi, Francesco; Lombardo, Federico

2017-02-01

The apparent ubiquity of binary random processes in physics and many other fields has attracted considerable attention from the modeling community. However, generation of binary sequences with prescribed autocorrelation is a challenging task owing to the discrete nature of the marginal distributions, which makes the application of classical spectral techniques problematic. We show that such methods can effectively be used if we focus on the parent continuous process of beta distributed transition probabilities rather than on the target binary process. This change of paradigm results in a simulation procedure effectively embedding a spectrum-based iterative amplitude-adjusted Fourier transform method devised for continuous processes. The proposed algorithm is fully general, requires minimal assumptions, and can easily simulate binary signals with power-law and exponentially decaying autocorrelation functions corresponding, for instance, to Hurst-Kolmogorov and Markov processes. An application to rainfall intermittency shows that the proposed algorithm can also simulate surrogate data preserving the empirical autocorrelation.

General simulation algorithm for autocorrelated binary processes

Science.gov (United States)

Serinaldi, Francesco; Lombardo, Federico

2017-02-01

The apparent ubiquity of binary random processes in physics and many other fields has attracted considerable attention from the modeling community. However, generation of binary sequences with prescribed autocorrelation is a challenging task owing to the discrete nature of the marginal distributions, which makes the application of classical spectral techniques problematic. We show that such methods can effectively be used if we focus on the parent continuous process of beta distributed transition probabilities rather than on the target binary process. This change of paradigm results in a simulation procedure effectively embedding a spectrum-based iterative amplitude-adjusted Fourier transform method devised for continuous processes. The proposed algorithm is fully general, requires minimal assumptions, and can easily simulate binary signals with power-law and exponentially decaying autocorrelation functions corresponding, for instance, to Hurst-Kolmogorov and Markov processes. An application to rainfall intermittency shows that the proposed algorithm can also simulate surrogate data preserving the empirical autocorrelation.

A Jump-Diffusion Model with Stochastic Volatility and Durations

DEFF Research Database (Denmark)

Wei, Wei; Pelletier, Denis

jumps in two ways: as exogenous sampling intervals, and through the interaction with volatility. We adopt a bivariate Ornstein-Ulenbeck process to model intraday volatility and conditional duration. We develop a MCMC algorithm for the inference on irregularly spaced multivariate processes with jumps...

A new iteration process for finite families of generalized lipschitz pseudo-contractive and generalized lipschitz accretive mappings

International Nuclear Information System (INIS)

Chidume, C.E.; Ofoedu, E.U.

2007-07-01

In this paper, we introduce a new iteration process and prove that it converges strongly to a common fixed point for a finite family of generalized Lipschitz nonlinear mappings in a real reflexive Banach space E with a with uniformly Gateaux differentiable norm if at least one member of the family is pseudo-contractive. We also prove that a slight modification of the process converges to a common zero for a finite family of generalized Lipschitz accretive operators defined on E. Results for nonexpansive families are obtained as easy corollaries. Finally, our new iteration process and our method of proof are of independent interest. (author)

Markov Jump Processes Approximating a Non-Symmetric Generalized Diffusion

International Nuclear Information System (INIS)

Limić, Nedžad

2011-01-01

Consider a non-symmetric generalized diffusion X(⋅) in ℝ d determined by the differential operator A(x) = -Σ ij ∂ i a ij (x)∂ j + Σ i b i (x)∂ i . In this paper the diffusion process is approximated by Markov jump processes X n (⋅), in homogeneous and isotropic grids G n ⊂ℝ d , which converge in distribution in the Skorokhod space D([0,∞),ℝ d ) to the diffusion X(⋅). The generators of X n (⋅) are constructed explicitly. Due to the homogeneity and isotropy of grids, the proposed method for d≥3 can be applied to processes for which the diffusion tensor {a ij (x)} 11 dd fulfills an additional condition. The proposed construction offers a simple method for simulation of sample paths of non-symmetric generalized diffusion. Simulations are carried out in terms of jump processes X n (⋅). For piece-wise constant functions a ij on ℝ d and piece-wise continuous functions a ij on ℝ 2 the construction and principal algorithm are described enabling an easy implementation into a computer code.

PECULIARITIES OF GENERALIZATION OF SIMILAR PHENOMENA IN THE PROCESS OF FISH HEAT TREATMENT

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V. A. Pokhol’chenko

2015-01-01

Full Text Available The theoretical presuppositions for the possibility of generalizing and similarity founding in dehydration and wet materials heating processes are studieded in this article. It is offered to carry out the given processes generalization by using dimensionless numbers of similarity. At the detailed analyzing of regularities of heat treatment processes of fish in different modes a significant amount of experienced material was successfully generalized on the basis of dimensionless simplex (similarity numbers. Using the dimensionless simplex allowed to detect a number of simple mathematical models for the studied phenomena. The generalized kinetic models of fish dehydration, the generalized dynamic models (changing moisture diffusion coefficients, the generalized kinetic models of fish heating (the temperature field changing in the products thickness, average volume and center were founded. These generalized mathematical models showed also relationship of dehydration and heating at the processes of fish semi-hot, hot smoking (drying and frying. The relationship of the results from the physical nature of the dehydration process, including a change in the binding energy of the moisture with the material to the extent of the process and the shrinkage impact on the rate of the product moisture removal is given in the article. The factors influencing the internal structure and properties of the raw material changing and retarding the dehydration processes are described there. There was a heating rate dependence of fish products on the chemical composition the geometric dimensions of the object of heating and on the coolant regime parameters. A unique opportunity is opened by using the generalized models, combined with empirically derived equations and the technique of engineering calculation of these processes, to design a rational modes of heat treatment of raw materials and to optimize the performance of thermal equipment.

A general conservative extension theorem in process algebras with inequalities

NARCIS (Netherlands)

d' Argenio, P.R.; Verhoef, Chris

1997-01-01

We prove a general conservative extension theorem for transition system based process theories with easy-to-check and reasonable conditions. The core of this result is another general theorem which gives sufficient conditions for a system of operational rules and an extension of it in order to

A General Accelerated Degradation Model Based on the Wiener Process.

Science.gov (United States)

Liu, Le; Li, Xiaoyang; Sun, Fuqiang; Wang, Ning

2016-12-06

Accelerated degradation testing (ADT) is an efficient tool to conduct material service reliability and safety evaluations by analyzing performance degradation data. Traditional stochastic process models are mainly for linear or linearization degradation paths. However, those methods are not applicable for the situations where the degradation processes cannot be linearized. Hence, in this paper, a general ADT model based on the Wiener process is proposed to solve the problem for accelerated degradation data analysis. The general model can consider the unit-to-unit variation and temporal variation of the degradation process, and is suitable for both linear and nonlinear ADT analyses with single or multiple acceleration variables. The statistical inference is given to estimate the unknown parameters in both constant stress and step stress ADT. The simulation example and two real applications demonstrate that the proposed method can yield reliable lifetime evaluation results compared with the existing linear and time-scale transformation Wiener processes in both linear and nonlinear ADT analyses.

A General Accelerated Degradation Model Based on the Wiener Process

Directory of Open Access Journals (Sweden)

Le Liu

2016-12-01

Full Text Available Accelerated degradation testing (ADT is an efficient tool to conduct material service reliability and safety evaluations by analyzing performance degradation data. Traditional stochastic process models are mainly for linear or linearization degradation paths. However, those methods are not applicable for the situations where the degradation processes cannot be linearized. Hence, in this paper, a general ADT model based on the Wiener process is proposed to solve the problem for accelerated degradation data analysis. The general model can consider the unit-to-unit variation and temporal variation of the degradation process, and is suitable for both linear and nonlinear ADT analyses with single or multiple acceleration variables. The statistical inference is given to estimate the unknown parameters in both constant stress and step stress ADT. The simulation example and two real applications demonstrate that the proposed method can yield reliable lifetime evaluation results compared with the existing linear and time-scale transformation Wiener processes in both linear and nonlinear ADT analyses.

A generalized fluctuation-dissipation theorem for the one-dimensional diffusion process

International Nuclear Information System (INIS)

Okabe, Y.

1985-01-01

The [α,β,γ]-Langevin equation describes the time evolution of a real stationary process with T-positivity (reflection positivity) originating in the axiomatic quantum field theory. For this [α,β,γ]-Langevin equation a generalized fluctuation-dissipation theorem is proved. We shall obtain, as its application, a generalized fluctuation-dissipation theorem for the one-dimensional non-linear diffusion process, which presents one solution of Ryogo Kubo's problem in physics. (orig.)

SIMULATION AND PREDICTION OF THE PROCESS BASED ON THE GENERAL LOGISTIC MAPPING

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V. V. Skalozub

2013-11-01

Full Text Available Purpose. The aim of the research is to build a model of the generalzed logistic mapping and assessment of the possibilities of its use for the formation of the mathematical description, as well as operational forecasts of parameters of complex dynamic processes described by the time series. Methodology. The research results are obtained on the basis of mathematical modeling and simulation of nonlinear systems using the tools of chaotic dynamics. Findings. A model of the generalized logistic mapping, which is used to interpret the characteristics of dynamic processes was proposed. We consider some examples of representations of processes based on enhanced logistic mapping varying the values of model parameters. The procedures of modeling and interpretation of the data on the investigated processes, represented by the time series, as well as the operational forecasting of parameters using the generalized model of logistic mapping were proposed. Originality. The paper proposes an improved mathematical model, generalized logistic mapping, designed for the study of nonlinear discrete dynamic processes. Practical value. The carried out research using the generalized logistic mapping of railway transport processes, in particular, according to assessment of the parameters of traffic volumes, indicate the great potential of its application in practice for solving problems of analysis, modeling and forecasting complex nonlinear discrete dynamical processes. The proposed model can be used, taking into account the conditions of uncertainty, irregularity, the manifestations of the chaotic nature of the technical, economic and other processes, including the railway ones.

Generalized epidemic process on modular networks.

Science.gov (United States)

Chung, Kihong; Baek, Yongjoo; Kim, Daniel; Ha, Meesoon; Jeong, Hawoong

2014-05-01

Social reinforcement and modular structure are two salient features observed in the spreading of behavior through social contacts. In order to investigate the interplay between these two features, we study the generalized epidemic process on modular networks with equal-sized finite communities and adjustable modularity. Using the analytical approach originally applied to clique-based random networks, we show that the system exhibits a bond-percolation type continuous phase transition for weak social reinforcement, whereas a discontinuous phase transition occurs for sufficiently strong social reinforcement. Our findings are numerically verified using the finite-size scaling analysis and the crossings of the bimodality coefficient.

Generalized Poisson processes in quantum mechanics and field theory

International Nuclear Information System (INIS)

Combe, P.; Rodriguez, R.; Centre National de la Recherche Scientifique, 13 - Marseille; Hoegh-Krohn, R.; Centre National de la Recherche Scientifique, 13 - Marseille; Sirugue, M.; Sirugue-Collin, M.; Centre National de la Recherche Scientifique, 13 - Marseille

1981-01-01

In section 2 we describe more carefully the generalized Poisson processes, giving a realization of the underlying probability space, and we characterize these processes by their characteristic functionals. Section 3 is devoted to the proof of the previous formula for quantum mechanical systems, with possibly velocity dependent potentials and in section 4 we give an application of the previous theory to some relativistic Bose field models. (orig.)

General programmed system for physiological signal processing

Energy Technology Data Exchange (ETDEWEB)

Tournier, E; Monge, J; Magnet, C; Sonrel, C

1975-01-01

Improvements made to the general programmed signal acquisition and processing system, Plurimat S, are described, the aim being to obtain a less specialized system adapted to the biological and medical field. In this modified system the acquisition will be simplified. The standard processings offered will be integrated to a real advanced language which will enable the user to create his own processings, the loss of speed being compensated by a greater flexibility and universality. The observation screen will be large and the quality of the recording very good so that a large signal fraction may be displayed. The data will be easily indexed and filed for subsequent display and processing. This system will be used for two kinds of task: it can either be specialized, as an integral part of measurement and diagnostic preparation equipment used routinely in clinical work (e.g. vectocardiographic examination), or its versatility can be used for studies of limited duration to gain information in a given field or to study new diagnosis or treatment methods.

Oligarchy as a phase transition: The effect of wealth-attained advantage in a Fokker-Planck description of asset exchange

Science.gov (United States)

Boghosian, Bruce M.; Devitt-Lee, Adrian; Johnson, Merek; Li, Jie; Marcq, Jeremy A.; Wang, Hongyan

2017-06-01

The ;Yard-Sale Model; of asset exchange is known to result in complete inequality-all of the wealth in the hands of a single agent. It is also known that, when this model is modified by introducing a simple model of redistribution based on the Ornstein-Uhlenbeck process, it admits a steady state exhibiting some features similar to the celebrated Pareto Law of wealth distribution. In the present work, we analyze the form of this steady-state distribution in much greater detail, using a combination of analytic and numerical techniques. We find that, while Pareto's Law is approximately valid for low redistribution, it gives way to something more similar to Gibrat's Law when redistribution is higher. Additionally, we prove in this work that, while this Pareto or Gibrat behavior may persist over many orders of magnitude, it ultimately gives way to gaussian decay at extremely large wealth. Also in this work, we introduce a bias in favor of the wealthier agent-what we call Wealth-Attained Advantage (WAA)-and show that this leads to the phenomenon of ;wealth condensation; when the bias exceeds a certain critical value. In the wealth-condensed state, a finite fraction of the total wealth of the population ;condenses; to the wealthiest agent. We examine this phenomenon in some detail, and derive the corresponding modification to the Fokker-Planck equation. We observe a second-order phase transition to a state of coexistence between an oligarch and a distribution of non-oligarchs. Finally, by studying the asymptotic behavior of the distribution in some detail, we show that the onset of wealth condensation has an abrupt reciprocal effect on the character of the non-oligarchical part of the distribution. Specifically, we show that the above-mentioned gaussian decay at extremely large wealth is valid both above and below criticality, but degenerates to exponential decay precisely at criticality.

Domain-General Factors Influencing Numerical and Arithmetic Processing

Directory of Open Access Journals (Sweden)

André Knops

2017-12-01

Full Text Available This special issue contains 18 articles that address the question how numerical processes interact with domain-general factors. We start the editorial with a discussion of how to define domain-general versus domain-specific factors and then discuss the contributions to this special issue grouped into two core numerical domains that are subject to domain-general influences (see Figure 1. The first group of contributions addresses the question how numbers interact with spatial factors. The second group of contributions is concerned with factors that determine and predict arithmetic understanding, performance and development. This special issue shows that domain-general (Table 1a as well as domain-specific (Table 1b abilities influence numerical and arithmetic performance virtually at all levels and make it clear that for the field of numerical cognition a sole focus on one or several domain-specific factors like the approximate number system or spatial-numerical associations is not sufficient. Vice versa, in most studies that included domain-general and domain-specific variables, domain-specific numerical variables predicted arithmetic performance above and beyond domain-general variables. Therefore, a sole focus on domain-general aspects such as, for example, working memory, to explain, predict and foster arithmetic learning is also not sufficient. Based on the articles in this special issue we conclude that both domain-general and domain-specific factors contribute to numerical cognition. But the how, why and when of their contribution still needs to be better understood. We hope that this special issue may be helpful to readers in constraining future theory and model building about the interplay of domain-specific and domain-general factors.

Integrable Floquet dynamics, generalized exclusion processes and "fused" matrix ansatz

Science.gov (United States)

Vanicat, Matthieu

2018-04-01

We present a general method for constructing integrable stochastic processes, with two-step discrete time Floquet dynamics, from the transfer matrix formalism. The models can be interpreted as a discrete time parallel update. The method can be applied for both periodic and open boundary conditions. We also show how the stationary distribution can be built as a matrix product state. As an illustration we construct parallel discrete time dynamics associated with the R-matrix of the SSEP and of the ASEP, and provide the associated stationary distributions in a matrix product form. We use this general framework to introduce new integrable generalized exclusion processes, where a fixed number of particles is allowed on each lattice site in opposition to the (single particle) exclusion process models. They are constructed using the fusion procedure of R-matrices (and K-matrices for open boundary conditions) for the SSEP and ASEP. We develop a new method, that we named "fused" matrix ansatz, to build explicitly the stationary distribution in a matrix product form. We use this algebraic structure to compute physical observables such as the correlation functions and the mean particle current.

An ordination of life histories using morphological proxies: capital vs. income breeding in insects.

Science.gov (United States)

Davis, Robert B; Javoiš, Juhan; Kaasik, Ants; Õunap, Erki; Tammaru, Toomas

2016-08-01

Predictive classifications of life histories are essential for evolutionary ecology. While attempts to apply a single approach to all organisms may be overambitious, recent advances suggest that more narrow ordination schemes can be useful. However, these schemes mostly lack easily observable proxies of the position of a species on respective axes. It has been proposed that, in insects, the degree of capital (vs. income) breeding, reflecting the importance of adult feeding for reproduction, correlates with various ecological traits at the level of among-species comparison. We sought to prove these ideas via rigorous phylogenetic comparative analyses. We used experimentally derived life-history data for 57 species of European Geometridae (Lepidoptera), and an original phylogenetic reconstruction. The degree of capital breeding was estimated based on morphological proxies, including relative abdomen size of females. Applying Brownian-motion-based comparative analyses (with an original update to include error estimates), we demonstrated the associations between the degree of capital breeding and larval diet breadth, sexual size dimorphism, and reproductive season. Ornstein-Uhlenbeck model based phylogenetic analysis suggested a causal relationship between the degree of capital breeding and diet breadth. Our study indicates that the gradation from capital to income breeding is an informative axis to ordinate life-history strategies in flying insects which are affected by the fecundity vs. mobility trade off, with the availability of easy to record proxies contributing to its predictive power in practical contexts. © 2016 by the Ecological Society of America.

The effects of evidence bounds on decision-making: theoretical and empirical developments

Directory of Open Access Journals (Sweden)

Jiaxiang eZhang

2012-08-01

Full Text Available Converging findings from behavioral, neurophysiological and neuroimaging studies suggest an integration-to-boundary mechanism governing decision formation and choice selection. This mechanism is supported by sequential sampling models of choice decisions, which can implement statistically optimal decision strategies for selecting between multiple alternative options on the basis of sensory evidence. This review focuses on recent developments in understanding the evidence boundary, an important component of decision-making raised by experimental findings and models. The article starts by reviewing the neurobiology of perceptual decisions and several influential sequential sampling models, in particular the drift-diffusion model, the Ornstein-Uhlenbeck model and the leaky-competing-accumulator model. In the second part, the article examines how the boundary may affect a model’s dynamics and performance and to what extent it may improve a model’s fits to experimental data. In the third part, the article examines recent findings that support the presence and site of boundaries in the brain. The article considers two questions: 1 whether the boundary is a spontaneous property of neural integrators, or is controlled by dedicated neural circuits; 2 if the boundary is variable, what could be the driving factors behind boundary changes? The review brings together studies using different experimental methods in seeking answers to these questions, highlights psychological and physiological factors that may be associated with the boundary and its changes, and further considers the evidence boundary as a generic mechanism to guide complex behavior.

Lévy processes on a generalized fractal comb

Science.gov (United States)

Sandev, Trifce; Iomin, Alexander; Méndez, Vicenç

2016-09-01

Comb geometry, constituted of a backbone and fingers, is one of the most simple paradigm of a two-dimensional structure, where anomalous diffusion can be realized in the framework of Markov processes. However, the intrinsic properties of the structure can destroy this Markovian transport. These effects can be described by the memory and spatial kernels. In particular, the fractal structure of the fingers, which is controlled by the spatial kernel in both the real and the Fourier spaces, leads to the Lévy processes (Lévy flights) and superdiffusion. This generalization of the fractional diffusion is described by the Riesz space fractional derivative. In the framework of this generalized fractal comb model, Lévy processes are considered, and exact solutions for the probability distribution functions are obtained in terms of the Fox H-function for a variety of the memory kernels, and the rate of the superdiffusive spreading is studied by calculating the fractional moments. For a special form of the memory kernels, we also observed a competition between long rests and long jumps. Finally, we considered the fractal structure of the fingers controlled by a Weierstrass function, which leads to the power-law kernel in the Fourier space. This is a special case, when the second moment exists for superdiffusion in this competition between long rests and long jumps.

Lévy processes on a generalized fractal comb

International Nuclear Information System (INIS)

Sandev, Trifce; Iomin, Alexander; Méndez, Vicenç

2016-01-01

Comb geometry, constituted of a backbone and fingers, is one of the most simple paradigm of a two-dimensional structure, where anomalous diffusion can be realized in the framework of Markov processes. However, the intrinsic properties of the structure can destroy this Markovian transport. These effects can be described by the memory and spatial kernels. In particular, the fractal structure of the fingers, which is controlled by the spatial kernel in both the real and the Fourier spaces, leads to the Lévy processes (Lévy flights) and superdiffusion. This generalization of the fractional diffusion is described by the Riesz space fractional derivative. In the framework of this generalized fractal comb model, Lévy processes are considered, and exact solutions for the probability distribution functions are obtained in terms of the Fox H -function for a variety of the memory kernels, and the rate of the superdiffusive spreading is studied by calculating the fractional moments. For a special form of the memory kernels, we also observed a competition between long rests and long jumps. Finally, we considered the fractal structure of the fingers controlled by a Weierstrass function, which leads to the power-law kernel in the Fourier space. This is a special case, when the second moment exists for superdiffusion in this competition between long rests and long jumps. (paper)

Arbitrage free pricing of forward and futures in the energy market

International Nuclear Information System (INIS)

Kloster, Kristian

2003-01-01

This thesis will describe a method for an arbitrage-free evaluation of forward and futures contracts in the Nordic electricity market. This is a market where it is not possible to hedge using the underlying asset which one normally would do. The electricity market is a relatively new market, and is less developed than the financial markets. The pricing of energy and energy derivatives are depending on factors like production, transport, storage etc. There are different approaches when pricing a forward contract in an energy market. With motivation from interest rate theory, one could model the forward prices directly in the risk neutral world. Another approach is to start out with a model for the spot prices in the physical world, and then derive theoretical forward prices, which then are fitted to observed forward prices. These and other approaches are described by Clewlow and Strickland in their book, Energy derivatives. This thesis uses the approach where I start out with a model for the spot price, and then derive theoretical forward prices. I use a generalization of the multifactor Schwartz model with seasonal trends and Ornstein Uhlenbeck processes to model the spot prices for electricity. This continuous-time model also incorporates mean-reversion, which is an important aspect of energy prices. Historical data for the spot prices is used to estimate my variables in the multi-factor Schwartz model. Then one can specify arbitrage-free prices for forward and futures based on the Schwartz model. The result from this procedure is a joint spot and forward price model in both the risk neutral and physical market, together with knowledge of the equivalent martingale measure chosen by the market. This measure can be interpreted as the market price of risk, which is of interest for risk management. In this setup both futures and forward contracts will have the same pricing dynamics, as the only difference between the two types of contracts is how the payment for the

Toward a General Research Process for Using Dubin's Theory Building Model

Science.gov (United States)

Holton, Elwood F.; Lowe, Janis S.

2007-01-01

Dubin developed a widely used methodology for theory building, which describes the components of the theory building process. Unfortunately, he does not define a research process for implementing his theory building model. This article proposes a seven-step general research process for implementing Dubin's theory building model. An example of a…

Weldability of general purpose heat source new-process iridium

International Nuclear Information System (INIS)

Kanne, W.R.

1987-01-01

Weldability tests on General Purpose Heat Source (GPHS) iridium capsules showed that a new iridium fabrication process reduced susceptibility to underbead cracking. Seventeen capsules were welded (a total of 255 welds) in four categories and the number of cracks in each weld was measured

The Burden of the Fellowship Interview Process on General Surgery Residents and Programs.

Science.gov (United States)

Watson, Shawna L; Hollis, Robert H; Oladeji, Lasun; Xu, Shin; Porterfield, John R; Ponce, Brent A

This study evaluated the effect of the fellowship interview process in a cohort of general surgery residents. We hypothesized that the interview process would be associated with significant clinical time lost, monetary expenses, and increased need for shift coverage. An online anonymous survey link was sent via e-mail to general surgery program directors in June 2014. Program directors distributed an additional survey link to current residents in their program who had completed the fellowship interview process. United States allopathic general surgery programs. Overall, 50 general surgery program directors; 72 general surgery residents. Program directors reported a fellowship application rate of 74.4%. Residents most frequently attended 8 to 12 interviews (35.2%). Most (57.7%) of residents reported missing 7 or more days of clinical training to attend interviews; these shifts were largely covered by other residents. Most residents (62.3%) spent over $4000 on the interview process. Program directors rated fellowship burden as an average of 6.7 on a 1 to 10 scale of disruption, with 10 being a significant disruption. Most of the residents (57.3%) were in favor of change in the interview process. We identified potential areas for improvement including options for coordinated interviews and improved content on program websites. The surgical fellowship match is relatively burdensome to residents and programs alike, and merits critical assessment for potential improvement. Published by Elsevier Inc.

Discrete-Event Execution Alternatives on General Purpose Graphical Processing Units

International Nuclear Information System (INIS)

Perumalla, Kalyan S.

2006-01-01

Graphics cards, traditionally designed as accelerators for computer graphics, have evolved to support more general-purpose computation. General Purpose Graphical Processing Units (GPGPUs) are now being used as highly efficient, cost-effective platforms for executing certain simulation applications. While most of these applications belong to the category of time-stepped simulations, little is known about the applicability of GPGPUs to discrete event simulation (DES). Here, we identify some of the issues and challenges that the GPGPU stream-based interface raises for DES, and present some possible approaches to moving DES to GPGPUs. Initial performance results on simulation of a diffusion process show that DES-style execution on GPGPU runs faster than DES on CPU and also significantly faster than time-stepped simulations on either CPU or GPGPU.

Using Self-Reflection To Increase Science Process Skills in the General Chemistry Laboratory

Science.gov (United States)

Veal, William R.; Taylor, Dawne; Rogers, Amy L.

2009-03-01

Self-reflection is a tool of instruction that has been used in the science classroom. Research has shown great promise in using video as a learning tool in the classroom. However, the integration of self-reflective practice using video in the general chemistry laboratory to help students develop process skills has not been done. Immediate video feedback and direct instruction were employed in a general chemistry laboratory course to improve students' mastery and understanding of basic and advanced process skills. Qualitative results and statistical analysis of quantitative data proved that self-reflection significantly helped students develop basic and advanced process skills, yet did not seem to influence the general understanding of the science content.

Is general intelligence little more than the speed of higher-order processing?

Science.gov (United States)

Schubert, Anna-Lena; Hagemann, Dirk; Frischkorn, Gidon T

2017-10-01

Individual differences in the speed of information processing have been hypothesized to give rise to individual differences in general intelligence. Consistent with this hypothesis, reaction times (RTs) and latencies of event-related potential have been shown to be moderately associated with intelligence. These associations have been explained either in terms of individual differences in some brain-wide property such as myelination, the speed of neural oscillations, or white-matter tract integrity, or in terms of individual differences in specific processes such as the signal-to-noise ratio in evidence accumulation, executive control, or the cholinergic system. Here we show in a sample of 122 participants, who completed a battery of RT tasks at 2 laboratory sessions while an EEG was recorded, that more intelligent individuals have a higher speed of higher-order information processing that explains about 80% of the variance in general intelligence. Our results do not support the notion that individuals with higher levels of general intelligence show advantages in some brain-wide property. Instead, they suggest that more intelligent individuals benefit from a more efficient transmission of information from frontal attention and working memory processes to temporal-parietal processes of memory storage. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

A generalized logarithmic image processing model based on the gigavision sensor model.

Science.gov (United States)

Deng, Guang

2012-03-01

The logarithmic image processing (LIP) model is a mathematical theory providing generalized linear operations for image processing. The gigavision sensor (GVS) is a new imaging device that can be described by a statistical model. In this paper, by studying these two seemingly unrelated models, we develop a generalized LIP (GLIP) model. With the LIP model being its special case, the GLIP model not only provides new insights into the LIP model but also defines new image representations and operations for solving general image processing problems that are not necessarily related to the GVS. A new parametric LIP model is also developed. To illustrate the application of the new scalar multiplication operation, we propose an energy-preserving algorithm for tone mapping, which is a necessary step in image dehazing. By comparing with results using two state-of-the-art algorithms, we show that the new scalar multiplication operation is an effective tool for tone mapping.

On the 2-orthogonal polynomials and the generalized birth and death processes

Directory of Open Access Journals (Sweden)

Zerouki Ebtissem

2006-01-01

Full Text Available We discuss the connections between the 2-orthogonal polynomials and the generalized birth and death processes. Afterwards, we find the sufficient conditions to give an integral representation of the transition probabilities from these processes.

The semi-Markov process. Generalizations and calculation rules for application in the analysis of systems

International Nuclear Information System (INIS)

Hirschmann, H.

1983-06-01

The consequences of the basic assumptions of the semi-Markov process as defined from a homogeneous renewal process with a stationary Markov condition are reviewed. The notion of the semi-Markov process is generalized by its redefinition from a nonstationary Markov renewal process. For both the nongeneralized and the generalized case a representation of the first order conditional state probabilities is derived in terms of the transition probabilities of the Markov renewal process. Some useful calculation rules (regeneration rules) are derived for the conditional state probabilities of the semi-Markov process. Compared to the semi-Markov process in its usual definition the generalized process allows the analysis of a larger class of systems. For instance systems with arbitrarily distributed lifetimes of their components can be described. There is also a chance to describe systems which are modified during time by forces or manipulations from outside. (Auth.)

Examination of Turkish Junior High-School Students' Perceptions of the General Problem-Solving Process

Science.gov (United States)

Ekici, Didem Inel

2016-01-01

This study aimed to determine Turkish junior high-school students' perceptions of the general problem-solving process. The Turkish junior high-school students' perceptions of the general problem-solving process were examined in relation to their gender, grade level, age and their grade point with regards to the science course identified in the…

General definitions of chaos for continuous and discrete-time processes

OpenAIRE

Vieru, Andrei

2008-01-01

A precise definition of chaos for discrete processes based on iteration already exists. We shall first reformulate it in a more general frame, taking into account the fact that discrete chaotic behavior is neither necessarily based on iteration nor strictly related to compact metric spaces or to bounded functions. Then we shall apply the central idea of this definition to continuous processes. We shall try to see what chaos is, regardless of the way it is generated.

[Contents of general flavonoides in Epimedium acuminatum Franch. and its differently-processed products].

Science.gov (United States)

Chen, H L; Wang, J K; Zhang, L L; Wu, Z Y

2000-04-01

Determining and comparing the contents of general flavonoides in four kinds of differently-processed products of Epimedium acuminatum. Determining the contents by ultraviolet spectrophotometry. The contents were found in the following seguence: unprocessed product, clearly-fried product, alcohol-broiled product, salt-broiled product, sheep-fat-broiled product. The average recovery rate was 96.01%, with a 0.74% RSD(n = 5). Heating causes the contents of general flavonoides in the processed products to decrease. These processed products are still often used in clinical treatment, for the reason that the adjuvant features certain coordinating and promoting functions. The study is to be pursued further.

An algebraic approach to laying a ghost to rest

International Nuclear Information System (INIS)

Nucci, M C; Leach, P G L

2010-01-01

In the recent literature there has been a resurgence of interest in the fourth-order field-theoretic model of Pais-Uhlenbeck (1950 Phys. Rev. 79 145-65) which has not had a good reception over the past half a century due to the existence of ghosts in the properties of the quantum mechanical solution. Bender and Mannheim (2008 J. Phys. A: Math. Theor. 41 304018) were successful in persuading the corresponding quantum operator to 'give up the ghost'. Their success had the advantage of making the model of Pais-Uhlenbeck acceptable to the physics community and in the process added further credit to the cause of advancement of the use of PT symmetry. We present a case for the acceptance of the Pais-Uhlenbeck model in the context of Dirac's theory by providing an Hamiltonian that is not quantum mechanically haunted. The essential point is the manner in which a fourth-order equation is rendered into a system of second-order equations. We show by means of the method of reduction of order (Nucci M C 1996 J. Math. Phys. 37 1772-5) that it is possible to construct a Hamiltonian that gives rise to a satisfactory quantal description without having to abandon Dirac.

Accelerated evolutionary rates in tropical and oceanic parmelioid lichens (Ascomycota

Directory of Open Access Journals (Sweden)

Blanco Oscar

2008-09-01

Full Text Available Abstract Background The rate of nucleotide substitutions is not constant across the Tree of Life, and departures from a molecular clock have been commonly reported. Within parmelioid lichens, the largest group of macrolichens, large discrepancies in branch lengths between clades were found in previous studies. Using an extended taxon sampling, we test for presence of significant rate discrepancies within and between these clades and test our a priori hypothesis that such rate discrepancies may be explained by shifts in moisture regime or other environmental conditions. Results In this paper, the first statistical evidence for accelerated evolutionary rate in lichenized ascomycetes is presented. Our results give clear evidence for a faster rate of evolution in two Hypotrachyna clades that includes species occurring in tropical and oceanic habitats in comparison with clades consisting of species occurring in semi-arid and temperate habitats. Further we explore potential links between evolutionary rates and shifts in habitat by comparing alternative Ornstein-Uhlenbeck models. Conclusion Although there was only weak support for a shift at the base of a second tropical clade, where the observed nucleotide substitution rate is high, overall support for a shift in environmental conditions at cladogenesis is very strong. This suggests that speciation in some lichen clades has proceeded by dispersal into a novel environment, followed by radiation within that environment. We found moderate support for a shift in moisture regime at the base of one tropical clade and a clade occurring in semi-arid regions and a shift in minimum temperature at the base of a boreal-temperate clade.

Non-Gaussian lineshapes and dynamics of time-resolved linear and nonlinear (correlation) spectra.

Science.gov (United States)

Dinpajooh, Mohammadhasan; Matyushov, Dmitry V

2014-07-17

Signatures of nonlinear and non-Gaussian dynamics in time-resolved linear and nonlinear (correlation) 2D spectra are analyzed in a model considering a linear plus quadratic dependence of the spectroscopic transition frequency on a Gaussian nuclear coordinate of the thermal bath (quadratic coupling). This new model is contrasted to the commonly assumed linear dependence of the transition frequency on the medium nuclear coordinates (linear coupling). The linear coupling model predicts equality between the Stokes shift and equilibrium correlation functions of the transition frequency and time-independent spectral width. Both predictions are often violated, and we are asking here the question of whether a nonlinear solvent response and/or non-Gaussian dynamics are required to explain these observations. We find that correlation functions of spectroscopic observables calculated in the quadratic coupling model depend on the chromophore's electronic state and the spectral width gains time dependence, all in violation of the predictions of the linear coupling models. Lineshape functions of 2D spectra are derived assuming Ornstein-Uhlenbeck dynamics of the bath nuclear modes. The model predicts asymmetry of 2D correlation plots and bending of the center line. The latter is often used to extract two-point correlation functions from 2D spectra. The dynamics of the transition frequency are non-Gaussian. However, the effect of non-Gaussian dynamics is limited to the third-order (skewness) time correlation function, without affecting the time correlation functions of higher order. The theory is tested against molecular dynamics simulations of a model polar-polarizable chromophore dissolved in a force field water.

Evolution of morphology and locomotor performance in anurans: relationships with microhabitat diversification.

Science.gov (United States)

Citadini, J M; Brandt, R; Williams, C R; Gomes, F R

2018-03-01

The relationships between morphology, performance, behavior and ecology provide evidence for multiple and complex phenotypic adaptations. The anuran body plan, for example, is evolutionarily conserved and shows clear specializations to jumping performance back at least to the early Jurassic. However, there are instances of more recent adaptation to habit diversity in the post-cranial skeleton, including relative limb length. The present study tested adaptive models of morphological evolution in anurans associated with the diversity of microhabitat use (semi-aquatic arboreal, fossorial, torrent, and terrestrial) in species of anuran amphibians from Brazil and Australia. We use phylogenetic comparative methods to determine which evolutionary models, including Brownian motion (BM) and Ornstein-Uhlenbeck (OU) are consistent with morphological variation observed across anuran species. Furthermore, this study investigated the relationship of maximum distance jumped as a function of components of morphological variables and microhabitat use. We found there are multiple optima of limb lengths associated to different microhabitats with a trend of increasing hindlimbs in torrent, arboreal, semi-aquatic whereas fossorial and terrestrial species evolve toward optima with shorter hindlimbs. Moreover, arboreal, semi-aquatic and torrent anurans have higher jumping performance and longer hindlimbs, when compared to terrestrial and fossorial species. We corroborate the hypothesis that evolutionary modifications of overall limb morphology have been important in the diversification of locomotor performance along the anuran phylogeny. Such evolutionary changes converged in different phylogenetic groups adapted to similar microhabitat use in two different zoogeographical regions. © 2018 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2018 European Society For Evolutionary Biology.

Process mapping as a framework for performance improvement in emergency general surgery.

Science.gov (United States)

DeGirolamo, Kristin; D'Souza, Karan; Hall, William; Joos, Emilie; Garraway, Naisan; Sing, Chad Kim; McLaughlin, Patrick; Hameed, Morad

2018-02-01

Emergency general surgery conditions are often thought of as being too acute for the development of standardized approaches to quality improvement. However, process mapping, a concept that has been applied extensively in manufacturing quality improvement, is now being used in health care. The objective of this study was to create process maps for small bowel obstruction in an effort to identify potential areas for quality improvement. We used the American College of Surgeons Emergency General Surgery Quality Improvement Program pilot database to identify patients who received nonoperative or operative management of small bowel obstruction between March 2015 and March 2016. This database, patient charts and electronic health records were used to create process maps from the time of presentation to discharge. Eighty-eight patients with small bowel obstruction (33 operative; 55 nonoperative) were identified. Patients who received surgery had a complication rate of 32%. The processes of care from the time of presentation to the time of follow-up were highly elaborate and variable in terms of duration; however, the sequences of care were found to be consistent. We used data visualization strategies to identify bottlenecks in care, and they showed substantial variability in terms of operating room access. Variability in the operative care of small bowel obstruction is high and represents an important improvement opportunity in general surgery. Process mapping can identify common themes, even in acute care, and suggest specific performance improvement measures.

Generalization bounds of ERM-based learning processes for continuous-time Markov chains.

Science.gov (United States)

Zhang, Chao; Tao, Dacheng

2012-12-01

Many existing results on statistical learning theory are based on the assumption that samples are independently and identically distributed (i.i.d.). However, the assumption of i.i.d. samples is not suitable for practical application to problems in which samples are time dependent. In this paper, we are mainly concerned with the empirical risk minimization (ERM) based learning process for time-dependent samples drawn from a continuous-time Markov chain. This learning process covers many kinds of practical applications, e.g., the prediction for a time series and the estimation of channel state information. Thus, it is significant to study its theoretical properties including the generalization bound, the asymptotic convergence, and the rate of convergence. It is noteworthy that, since samples are time dependent in this learning process, the concerns of this paper cannot (at least straightforwardly) be addressed by existing methods developed under the sample i.i.d. assumption. We first develop a deviation inequality for a sequence of time-dependent samples drawn from a continuous-time Markov chain and present a symmetrization inequality for such a sequence. By using the resultant deviation inequality and symmetrization inequality, we then obtain the generalization bounds of the ERM-based learning process for time-dependent samples drawn from a continuous-time Markov chain. Finally, based on the resultant generalization bounds, we analyze the asymptotic convergence and the rate of convergence of the learning process.

Process error rates in general research applications to the Human ...

African Journals Online (AJOL)

Objective. To examine process error rates in applications for ethics clearance of health research. Methods. Minutes of 586 general research applications made to a human health research ethics committee (HREC) from April 2008 to March 2009 were examined. Rates of approval were calculated and reasons for requiring ...

Fokker-Planck modeling of pitting corrosion in underground pipelines

Energy Technology Data Exchange (ETDEWEB)

Camacho, Eliana Nogueira [Risco Ambiental Engenharia, Rio de Janeiro, RJ (Brazil); Melo, Paulo F. Frutuoso e [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Saldanha, Pedro Luiz C. [Comissao Nacional de Energia Nuclear (CGRC/CNEN), Rio de Janeiro, RJ (Brazil). Coordenacao Geral de Reatores e Ciclo do Combustivel; Silva, Edson de Pinho da [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil). Dept. of Physics

2011-07-01

Full text: The stochastic nature of pitting corrosion has been recognized since the 1930s. It has been learned that this damage retains no memory of its past. Instead, the future state is determined only by the knowledge of its present state. This Markovian property that underlies the stochastic process governing pitting corrosion has been explored as a discrete Markovian process by many authors since the beginning of the 1990s for underground pipelines of the oil and gas industries and nuclear power plants. Corrosion is a genuine continuous time and space state Markovian process, so to model it as a discrete time and/or state space is an approximation to the problem. Markovian chains approaches, with an increasing number of states, could involve a large number of parameters, the transition rates between states, to be experimentally determined. Besides, such an increase in the number of states produces matrices with huge dimensions leading to time-consuming computational solutions. Recent approaches involving Markovian discrete process have overcome those difficulties but, on the other hand, a large number of soil and pipe stochastic variables have to be known. In this work we propose a continuous time and space state approach to the evolution of pit corrosion depths in underground pipelines. In order to illustrate the application of the model for defect depth growth a combination of real life data and Monte Carlo simulation was used. The process is described by a Fokker-Planck equation. The Fokker-Planck equation is completely determined by the knowledge of two functions known as the drift and diffusion coefficients. In this work we also show that those functions can be estimated from corrosion depth data from in-line inspections. Some particular forms of drift and diffusion coefficients lead to particular Fokker-Planck equations for which analytical solutions are known, as is the case for the Wiener process, the Ornstein-Uhlenbeck process and the Brownian motion

GENERAL ALGORITHMIC SCHEMA OF THE PROCESS OF THE CHILL AUXILIARIES PROJECTION

Directory of Open Access Journals (Sweden)

A. N. Chichko

2006-01-01

Full Text Available The general algorithmic diagram of systematization of the existing approaches to the process of projection is offered and the foundation of computer system of the chill mold arming construction is laid.

Non-rigid ultrasound image registration using generalized relaxation labeling process

Science.gov (United States)

Lee, Jong-Ha; Seong, Yeong Kyeong; Park, MoonHo; Woo, Kyoung-Gu; Ku, Jeonghun; Park, Hee-Jun

2013-03-01

This research proposes a novel non-rigid registration method for ultrasound images. The most predominant anatomical features in medical images are tissue boundaries, which appear as edges. In ultrasound images, however, other features can be identified as well due to the specular reflections that appear as bright lines superimposed on the ideal edge location. In this work, an image's local phase information (via the frequency domain) is used to find the ideal edge location. The generalized relaxation labeling process is then formulated to align the feature points extracted from the ideal edge location. In this work, the original relaxation labeling method was generalized by taking n compatibility coefficient values to improve non-rigid registration performance. This contextual information combined with a relaxation labeling process is used to search for a correspondence. Then the transformation is calculated by the thin plate spline (TPS) model. These two processes are iterated until the optimal correspondence and transformation are found. We have tested our proposed method and the state-of-the-art algorithms with synthetic data and bladder ultrasound images of in vivo human subjects. Experiments show that the proposed method improves registration performance significantly, as compared to other state-of-the-art non-rigid registration algorithms.

General induction at companies - between an administrative process and a sociological phenomenon

Directory of Open Access Journals (Sweden)

Héctor L. Bermúdez Restrepo

2012-12-01

Full Text Available From the example of the process of general induction into the organization and using certain sociological resources, shows paradox are specialists in human management: is to carefor the motivation and the welfare of workers to achieve its high performance, their fidelity and his tenure at the company; However, current mutations of the social architecture in general and of work in particular –as structure of organized action– force thinking that organizational loyalty tends to be increasingly unlikely and that, conversely, the current personnel administration processes appear made inappropriate notions and appear to contribute directly to the adversities of human beings in organizational settings.

41 CFR 102-37.50 - What is the general process for requesting surplus property for donation?

Science.gov (United States)

2010-07-01

... process for requesting surplus property for donation? 102-37.50 Section 102-37.50 Public Contracts and... REGULATION PERSONAL PROPERTY 37-DONATION OF SURPLUS PERSONAL PROPERTY General Provisions Donation Overview § 102-37.50 What is the general process for requesting surplus property for donation? The process for...

General methodology for exergy balance in ProSimPlus® process simulator

International Nuclear Information System (INIS)

Ghannadzadeh, Ali; Thery-Hetreux, Raphaële; Baudouin, Olivier; Baudet, Philippe; Floquet, Pascal; Joulia, Xavier

2012-01-01

This paper presents a general methodology for exergy balance in chemical and thermal processes integrated in ProSimPlus ® as a well-adapted process simulator for energy efficiency analysis. In this work, as well as using the general expressions for heat and work streams, the whole exergy balance is presented within only one software in order to fully automate exergy analysis. In addition, after exergy balance, the essential elements such as source of irreversibility for exergy analysis are presented to help the user for modifications on either process or utility system. The applicability of the proposed methodology in ProSimPlus ® is shown through a simple scheme of Natural Gas Liquids (NGL) recovery process and its steam utility system. The methodology does not only provide the user with necessary exergetic criteria to pinpoint the source of exergy losses, it also helps the user to find the way to reduce the exergy losses. These features of the proposed exergy calculator make it preferable for its implementation in ProSimPlus ® to define the most realistic and profitable retrofit projects on the existing chemical and thermal plants. -- Highlights: ► A set of new expressions for calculation of exergy of material streams is developed. ► A general methodology for exergy balance in ProSimPlus ® is presented. ► A panel of solutions based on exergy analysis is provided to help the user for modifications on process flowsheets. ► The exergy efficiency is chosen as a variable in a bi-criteria optimization.

On-line validation of linear process models using generalized likelihood ratios

International Nuclear Information System (INIS)

Tylee, J.L.

1981-12-01

A real-time method for testing the validity of linear models of nonlinear processes is described and evaluated. Using generalized likelihood ratios, the model dynamics are continually monitored to see if the process has moved far enough away from the nominal linear model operating point to justify generation of a new linear model. The method is demonstrated using a seventh-order model of a natural circulation steam generator

Use of general purpose graphics processing units with MODFLOW

Science.gov (United States)

Hughes, Joseph D.; White, Jeremy T.

2013-01-01

To evaluate the use of general-purpose graphics processing units (GPGPUs) to improve the performance of MODFLOW, an unstructured preconditioned conjugate gradient (UPCG) solver has been developed. The UPCG solver uses a compressed sparse row storage scheme and includes Jacobi, zero fill-in incomplete, and modified-incomplete lower-upper (LU) factorization, and generalized least-squares polynomial preconditioners. The UPCG solver also includes options for sequential and parallel solution on the central processing unit (CPU) using OpenMP. For simulations utilizing the GPGPU, all basic linear algebra operations are performed on the GPGPU; memory copies between the central processing unit CPU and GPCPU occur prior to the first iteration of the UPCG solver and after satisfying head and flow criteria or exceeding a maximum number of iterations. The efficiency of the UPCG solver for GPGPU and CPU solutions is benchmarked using simulations of a synthetic, heterogeneous unconfined aquifer with tens of thousands to millions of active grid cells. Testing indicates GPGPU speedups on the order of 2 to 8, relative to the standard MODFLOW preconditioned conjugate gradient (PCG) solver, can be achieved when (1) memory copies between the CPU and GPGPU are optimized, (2) the percentage of time performing memory copies between the CPU and GPGPU is small relative to the calculation time, (3) high-performance GPGPU cards are utilized, and (4) CPU-GPGPU combinations are used to execute sequential operations that are difficult to parallelize. Furthermore, UPCG solver testing indicates GPGPU speedups exceed parallel CPU speedups achieved using OpenMP on multicore CPUs for preconditioners that can be easily parallelized.

Information processing speed mediates the relationship between white matter and general intelligence in schizophrenia.

Science.gov (United States)

Alloza, Clara; Cox, Simon R; Duff, Barbara; Semple, Scott I; Bastin, Mark E; Whalley, Heather C; Lawrie, Stephen M

2016-08-30

Several authors have proposed that schizophrenia is the result of impaired connectivity between specific brain regions rather than differences in local brain activity. White matter abnormalities have been suggested as the anatomical substrate for this dysconnectivity hypothesis. Information processing speed may act as a key cognitive resource facilitating higher order cognition by allowing multiple cognitive processes to be simultaneously available. However, there is a lack of established associations between these variables in schizophrenia. We hypothesised that the relationship between white matter and general intelligence would be mediated by processing speed. White matter water diffusion parameters were studied using Tract-based Spatial Statistics and computed within 46 regions-of-interest (ROI). Principal component analysis was conducted on these white matter ROI for fractional anisotropy (FA) and mean diffusivity, and on neurocognitive subtests to extract general factors of white mater structure (gFA, gMD), general intelligence (g) and processing speed (gspeed). There was a positive correlation between g and gFA (r= 0.67, p =0.001) that was partially and significantly mediated by gspeed (56.22% CI: 0.10-0.62). These findings suggest a plausible model of structure-function relations in schizophrenia, whereby white matter structure may provide a neuroanatomical substrate for general intelligence, which is partly supported by speed of information processing. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Generalized Inferences about the Mean Vector of Several Multivariate Gaussian Processes

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Pilar Ibarrola

2015-01-01

Full Text Available We consider in this paper the problem of comparing the means of several multivariate Gaussian processes. It is assumed that the means depend linearly on an unknown vector parameter θ and that nuisance parameters appear in the covariance matrices. More precisely, we deal with the problem of testing hypotheses, as well as obtaining confidence regions for θ. Both methods will be based on the concepts of generalized p value and generalized confidence region adapted to our context.

Shedding new light on Gaussian harmonic analysis

NARCIS (Netherlands)

Teuwen, J.J.B.

2016-01-01

This dissertation consists out of two rather disjoint parts. One part concerns some results on Gaussian harmonic analysis and the other on an optimization problem in optics. In the first part we study the Ornstein–Uhlenbeck process with respect to the Gaussian measure. We focus on two areas. One is

Information in general medical practices: the information processing model.

Science.gov (United States)

Crowe, Sarah; Tully, Mary P; Cantrill, Judith A

2010-04-01

The need for effective communication and handling of secondary care information in general practices is paramount. To explore practice processes on receiving secondary care correspondence in a way that integrates the information needs and perceptions of practice staff both clinical and administrative. Qualitative study using semi-structured interviews with a wide range of practice staff (n = 36) in nine practices in the Northwest of England. Analysis was based on the framework approach using N-Vivo software and involved transcription, familiarization, coding, charting, mapping and interpretation. The 'information processing model' was developed to describe the six stages involved in practice processing of secondary care information. These included the amendment or updating of practice records whilst simultaneously or separately actioning secondary care recommendations, using either a 'one-step' or 'two-step' approach, respectively. Many factors were found to influence each stage and impact on the continuum of patient care. The primary purpose of processing secondary care information is to support patient care; this study raises the profile of information flow and usage within practices as an issue requiring further consideration.

On the speed towards the mean for continuous time autoregressive moving average processes with applications to energy markets

International Nuclear Information System (INIS)

Benth, Fred Espen; Taib, Che Mohd Imran Che

2013-01-01

We extend the concept of half life of an Ornstein–Uhlenbeck process to Lévy-driven continuous-time autoregressive moving average processes with stochastic volatility. The half life becomes state dependent, and we analyze its properties in terms of the characteristics of the process. An empirical example based on daily temperatures observed in Petaling Jaya, Malaysia, is presented, where the proposed model is estimated and the distribution of the half life is simulated. The stationarity of the dynamics yield futures prices which asymptotically tend to constant at an exponential rate when time to maturity goes to infinity. The rate is characterized by the eigenvalues of the dynamics. An alternative description of this convergence can be given in terms of our concept of half life. - Highlights: • The concept of half life is extended to Levy-driven continuous time autoregressive moving average processes • The dynamics of Malaysian temperatures are modeled using a continuous time autoregressive model with stochastic volatility • Forward prices on temperature become constant when time to maturity tends to infinity • Convergence in time to maturity is at an exponential rate given by the eigenvalues of the model temperature model

Generalized enthalpy model of a high-pressure shift freezing process

KAUST Repository

Smith, N. A. S.

2012-05-02

High-pressure freezing processes are a novel emerging technology in food processing, offering significant improvements to the quality of frozen foods. To be able to simulate plateau times and thermal history under different conditions, in this work, we present a generalized enthalpy model of the high-pressure shift freezing process. The model includes the effects of pressure on conservation of enthalpy and incorporates the freezing point depression of non-dilute food samples. In addition, the significant heat-transfer effects of convection in the pressurizing medium are accounted for by solving the two-dimensional Navier-Stokes equations. We run the model for several numerical tests where the food sample is agar gel, and find good agreement with experimental data from the literature. © 2012 The Royal Society.

The role of culture in the general practice consultation process.

Science.gov (United States)

Ali, Nasreen; Atkin, Karl; Neal, Richard

2006-11-01

In this paper, we will examine the importance of culture and ethnicity in the general practice consultation process. Good communication is associated with positive health outcomes. We will, by presenting qualitative material from an empirical study, examine the way in which communication within the context of a general practitioner (GP) consultation may be affected by ethnicity and cultural factors. The aim of the study was to provide a detailed understanding of the ways in which white and South Asian patients communicate with white GPs and to explore any similarities and differences in communication. This paper reports on South Asian and white patients' explanations of recent videotaped consultations with their GP. We specifically focus on the ways in which issues of ethnic identity impacted upon the GP consultation process, by exploring how our sample of predominantly white GPs interacted with their South Asian patients and the extent to which the GP listened to the patients' needs, gave patients information, engaged in social conversation and showed friendliness. We then go on to examine patients' suggestions on improvements (if any) to the consultation. We conclude, by showing how a non-essentialist understanding of culture helps to comprehend the consultation process when the patients are from Great Britain's ethnicised communities. Our findings, however, raise generic issues of relevance to all multi-racial and multi-ethnic societies.

Understanding price discovery in interconnected markets: Generalized Langevin process approach and simulation

Science.gov (United States)

Schenck, Natalya A.; Horvath, Philip A.; Sinha, Amit K.

2018-02-01

While the literature on price discovery process and information flow between dominant and satellite market is exhaustive, most studies have applied an approach that can be traced back to Hasbrouck (1995) or Gonzalo and Granger (1995). In this paper, however, we propose a Generalized Langevin process with asymmetric double-well potential function, with co-integrated time series and interconnected diffusion processes to model the information flow and price discovery process in two, a dominant and a satellite, interconnected markets. A simulated illustration of the model is also provided.

General Template for the FMEA Applications in Primary Food Processing.

Science.gov (United States)

Özilgen, Sibel; Özilgen, Mustafa

Data on the hazards involved in the primary steps of processing cereals, fruit and vegetables, milk and milk products, meat and meat products, and fats and oils are compiled with a wide-ranging literature survey. After determining the common factors from these data, a general FMEA template is offered, and its use is explained with a case study on pasteurized milk production.

Ergodicity breaking, ageing, and confinement in generalized diffusion processes with position and time dependent diffusivity

International Nuclear Information System (INIS)

Cherstvy, Andrey G; Metzler, Ralf

2015-01-01

We study generalized anomalous diffusion processes whose diffusion coefficient D(x, t) ∼ D 0 |x| α t β depends on both the position x of the test particle and the process time t. This process thus combines the features of scaled Brownian motion and heterogeneous diffusion parent processes. We compute the ensemble and time averaged mean squared displacements of this generalized diffusion process. The scaling exponent of the ensemble averaged mean squared displacement is shown to be the product of the critical exponents of the parent processes, and describes both subdiffusive and superdiffusive systems. We quantify the amplitude fluctuations of the time averaged mean squared displacement as function of the length of the time series and the lag time. In particular, we observe a weak ergodicity breaking of this generalized diffusion process: even in the long time limit the ensemble and time averaged mean squared displacements are strictly disparate. When we start to observe this process some time after its initiation we observe distinct features of ageing. We derive a universal ageing factor for the time averaged mean squared displacement containing all information on the ageing time and the measurement time. External confinement is shown to alter the magnitudes and statistics of the ensemble and time averaged mean squared displacements. (paper)

Brownian motion under dynamic disorder: effects of memory on the decay of the non-Gaussianity parameter

Science.gov (United States)

Tyagi, Neha; Cherayil, Binny J.

2018-03-01

The increasingly widespread occurrence in complex fluids of particle motion that is both Brownian and non-Gaussian has recently been found to be successfully modeled by a process (frequently referred to as ‘diffusing diffusivity’) in which the white noise that governs Brownian diffusion is itself stochastically modulated by either Ornstein–Uhlenbeck dynamics or by two-state noise. But the model has so far not been able to account for an aspect of non-Gaussian Brownian motion that is also commonly observed: a non-monotonic decay of the parameter that quantifies the extent of deviation from Gaussian behavior. In this paper, we show that the inclusion of memory effects in the model—via a generalized Langevin equation—can rationalise this phenomenon.

Macroevolutionary diversification with limited niche disparity in a species-rich lineage of cold-climate lizards.

Science.gov (United States)

Reaney, Ashley M; Saldarriaga-Córdoba, Mónica; Pincheira-Donoso, Daniel

2018-02-06

Life diversifies via adaptive radiation when natural selection drives the evolution of ecologically distinct species mediated by their access to novel niche space, or via non-adaptive radiation when new species diversify while retaining ancestral niches. However, while cases of adaptive radiation are widely documented, examples of non-adaptively radiating lineages remain rarely observed. A prolific cold-climate lizard radiation from South America (Phymaturus), sister to a hyper-diverse adaptive radiation (Liolaemus), has extensively diversified phylogenetically and geographically, but with exceptionally minimal ecological and life-history diversification. This lineage, therefore, may offer unique opportunities to investigate the non-adaptive basis of diversification, and in combination with Liolaemus, to cover the whole spectrum of modes of diversification predicted by theory, from adaptive to non-adaptive. Using phylogenetic macroevolutionary modelling performed on a newly created 58-species molecular tree, we establish the tempo and mode of diversification in the Phymaturus radiation. Lineage accumulation in Phymaturus opposes a density-dependent (or 'niche-filling') process of diversification. Concurrently, we found that body size diversification is better described by an Ornstein-Uhlenbeck evolutionary model, suggesting stabilizing selection as the mechanism underlying niche conservatism (i.e., maintaining two fundamental size peaks), and which has predominantly evolved around two major adaptive peaks on a 'Simpsonian' adaptive landscape. Lineage diversification of the Phymaturus genus does not conform to an adaptive radiation, as it is characterised by a constant rate of species accumulation during the clade's history. Their strict habitat requirements (rocky outcrops), predominantly invariant herbivory, and especially the constant viviparous reproduction across species have likely limited their opportunities for adaptive diversifications throughout novel

The process of patient enablement in general practice nurse consultations: a grounded theory study.

Science.gov (United States)

Desborough, Jane; Banfield, Michelle; Phillips, Christine; Mills, Jane

2017-05-01

The aim of this study was to gain insight into the process of patient enablement in general practice nursing consultations. Enhanced roles for general practice nurses may benefit patients through a range of mechanisms, one of which may be increasing patient enablement. In studies with general practitioners enhanced patient enablement has been associated with increases in self-efficacy and skill development. This study used a constructivist grounded theory design. In-depth interviews were conducted with 16 general practice nurses and 23 patients from 21 general practices between September 2013 - March 2014. Data generation and analysis were conducted concurrently using constant comparative analysis and theoretical sampling focussing on the process and outcomes of patient enablement. Use of the storyline technique supported theoretical coding and integration of the data into a theoretical model. A clearly defined social process that fostered and optimised patient enablement was constructed. The theory of 'developing enabling healthcare partnerships between nurses and patients in general practice' incorporates three stages: triggering enabling healthcare partnerships, tailoring care and the manifestation of patient enablement. Patient enablement was evidenced through: 1. Patients' understanding of their unique healthcare requirements informing their health seeking behaviours and choices; 2. Patients taking an increased lead in their partnership with a nurse and seeking choices in their care and 3. Patients getting health care that reflected their needs, preferences and goals. This theoretical model is in line with a patient-centred model of health care and is particularly suited to patients with chronic disease. © 2016 John Wiley & Sons Ltd.

Gross and Fine Structure of Pion Production Excitation Functions in {bold {ital p}}-Nucleus and Nucleus-Nucleus Reactions

Energy Technology Data Exchange (ETDEWEB)

Jakobsson, B.; Berg, M.; Carlen, L.; Elmer, R.; Fokin, A.; Ghetti, R.; Martensson, J.; Noren, B.; Oskarsson, A.; Whitlow, H.J. [Department of Physics, University of Lund, Lund (Sweden); Ekstroem, C.; Ericsson, G.; Romanski, J.; van Veldhuizen, E.J.; Westerberg, L. [The Svedberg Laboratory and Department of Neutron Physics, University of Uppsala, Uppsala (Sweden); Julien, J. [Centre d`Etudes Nucleaires, Saclay (France); Skeppstedt, O. [Department of Physics, Chalmers Institute of Technology, Gothenburg (Sweden); Nyboe, K.; Thorsteinsen, T.F.; Amirelmi, S. [Department of Physics, University of Bergen, Bergen (Norway); Guttormsen, M.; Lo/vho/iden, G. [Department of Physics, University of Oslo, Oslo (Norway); Bellini, V.; Palazzolo, F.; Sperduto, M.L. [Istituto Nazionale di Fisica Nucleare/Laboratorio Nazionale del Sud, University of Catania, Catania (Italy); Bondorf, J.P.; Mishustin, I. [Niels Bohr Institute, Copenhagen (Denmark); Avdeichikov, V. [Joint Institute for Nuclear Research, Dubna (Russia); Lozhkin, O.V.; Murin, Y. [V.G. Khlopin Radium Institute, St.Petersburg (Russia)

1997-05-01

Slow ramping of the CELSIUS storage ring has been utilized to measure the yield of charged pions in proton and heavy ion induced collisions with continuously varying beam energy. Boltzmann-Uehling-Uhlenbeck predictions, including Fermi momenta of nucleons in nuclei, follow the general shape of the p-nucleus excitation functions quite well except for a general overestimation of the backward emission. For heavy ion reactions the calculated yield also falls off faster with decreasing beam energy than the data. No statistically significant narrow resonances are observed. {copyright} {ital 1997} {ital The American Physical Society}

Toward a model framework of generalized parallel componential processing of multi-symbol numbers.

Science.gov (United States)

Huber, Stefan; Cornelsen, Sonja; Moeller, Korbinian; Nuerk, Hans-Christoph

2015-05-01

In this article, we propose and evaluate a new model framework of parallel componential multi-symbol number processing, generalizing the idea of parallel componential processing of multi-digit numbers to the case of negative numbers by considering the polarity signs similar to single digits. In a first step, we evaluated this account by defining and investigating a sign-decade compatibility effect for the comparison of positive and negative numbers, which extends the unit-decade compatibility effect in 2-digit number processing. Then, we evaluated whether the model is capable of accounting for previous findings in negative number processing. In a magnitude comparison task, in which participants had to single out the larger of 2 integers, we observed a reliable sign-decade compatibility effect with prolonged reaction times for incompatible (e.g., -97 vs. +53; in which the number with the larger decade digit has the smaller, i.e., negative polarity sign) as compared with sign-decade compatible number pairs (e.g., -53 vs. +97). Moreover, an analysis of participants' eye fixation behavior corroborated our model of parallel componential processing of multi-symbol numbers. These results are discussed in light of concurrent theoretical notions about negative number processing. On the basis of the present results, we propose a generalized integrated model framework of parallel componential multi-symbol processing. (c) 2015 APA, all rights reserved).

Big cat, small cat: reconstructing body size evolution in living and extinct Felidae.

Science.gov (United States)

Cuff, A R; Randau, M; Head, J; Hutchinson, J R; Pierce, S E; Goswami, A

2015-08-01

The evolution of body mass is a fundamental topic in evolutionary biology, because it is closely linked to manifold life history and ecological traits and is readily estimable for many extinct taxa. In this study, we examine patterns of body mass evolution in Felidae (Placentalia, Carnivora) to assess the effects of phylogeny, mode of evolution, and the relationship between body mass and prey choice in this charismatic mammalian clade. Our data set includes 39 extant and 26 extinct taxa, with published body mass data supplemented by estimates based on condylobasal length. These data were run through 'SURFACE' and 'bayou' to test for patterns of body mass evolution and convergence between taxa. Body masses of felids are significantly different among prey choice groupings (small, mixed and large). We find that body mass evolution in cats is strongly influenced by phylogeny, but different patterns emerged depending on inclusion of extinct taxa and assumptions about branch lengths. A single Ornstein-Uhlenbeck optimum best explains the distribution of body masses when first-occurrence data were used for the fossil taxa. However, when mean occurrence dates or last known occurrence dates were used, two selective optima for felid body mass were recovered in most analyses: a small optimum around 5 kg and a large one around 100 kg. Across living and extinct cats, we infer repeated evolutionary convergences towards both of these optima, but, likely due to biased extinction of large taxa, our results shift to supporting a Brownian motion model when only extant taxa are included in analyses. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Evolutionary change in physiological phenotypes along the human lineage.

Science.gov (United States)

Vining, Alexander Q; Nunn, Charles L

2016-01-01

Research in evolutionary medicine provides many examples of how evolution has shaped human susceptibility to disease. Traits undergoing rapid evolutionary change may result in associated costs or reduce the energy available to other traits. We hypothesize that humans have experienced more such changes than other primates as a result of major evolutionary change along the human lineage. We investigated 41 physiological traits across 50 primate species to identify traits that have undergone marked evolutionary change along the human lineage. We analysed the data using two Bayesian phylogenetic comparative methods. One approach models trait covariation in non-human primates and predicts human phenotypes to identify whether humans are evolutionary outliers. The other approach models adaptive shifts under an Ornstein-Uhlenbeck model of evolution to assess whether inferred shifts are more common on the human branch than on other primate lineages. We identified four traits with strong evidence for an evolutionary increase on the human lineage (amylase, haematocrit, phosphorus and monocytes) and one trait with strong evidence for decrease (neutrophilic bands). Humans exhibited more cases of distinct evolutionary change than other primates. Human physiology has undergone increased evolutionary change compared to other primates. Long distance running may have contributed to increases in haematocrit and mean corpuscular haemoglobin concentration, while dietary changes are likely related to increases in amylase. In accordance with the pathogen load hypothesis, human monocyte levels were increased, but many other immune-related measures were not. Determining the mechanisms underlying conspicuous evolutionary change in these traits may provide new insights into human disease. The Author(s) 2016. Published by Oxford University Press on behalf of the Foundation for Evolution, Medicine, and Public Health.

Connecting proximate mechanisms and evolutionary patterns: pituitary gland size and mammalian life history.

Science.gov (United States)

Kamilar, J M; Tecot, S R

2015-11-01

At the proximate level, hormones are known to play a critical role in influencing the life history of mammals, including humans. The pituitary gland is directly responsible for producing several hormones, including those related to growth and reproduction. Although we have a basic understanding of how hormones affect life history characteristics, we still have little knowledge of this relationship in an evolutionary context. We used data from 129 mammal species representing 14 orders to investigate the relationship between pituitary gland size and life history variation. Because pituitary gland size should be related to hormone production and action, we predicted that species with relatively large pituitaries should be associated with fast life histories, especially increased foetal and post-natal growth rates. Phylogenetic analyses revealed that total pituitary size and the size of the anterior lobe of the pituitary significantly predicted a life history axis that was correlated with several traits including body mass, and foetal and post-natal growth rates. Additional models directly examining the association between relative pituitary size and growth rates produced concordant results. We also found that relative pituitary size variation across mammals was best explained by an Ornstein-Uhlenbeck model of evolution, suggesting an important role of stabilizing selection. Our results support the idea that the size of the pituitary is linked to life history variation through evolutionary time. This pattern is likely due to mediating hormone levels but additional work is needed. We suggest that future investigations incorporating endocrine gland size may be critical for understanding life history evolution. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Process evaluation of a practice nurse-led smoking cessation trial in Australian general practice: views of general practitioners and practice nurses.

Science.gov (United States)

Halcomb, Elizabeth J; Furler, John S; Hermiz, Oshana S; Blackberry, Irene D; Smith, Julie P; Richmond, Robyn L; Zwar, Nicholas A

2015-08-01

Support in primary care can assist smokers to quit successfully, but there are barriers to general practitioners (GPs) providing this support routinely. Practice nurses (PNs) may be able to effectively take on this role. The aim of this study was to perform a process evaluation of a PN-led smoking cessation intervention being tested in a randomized controlled trial in Australian general practice. Process evaluation was conducted by means of semi-structured telephone interviews with GPs and PNs allocated in the intervention arm (Quit with PN) of the Quit in General Practice trial. Interviews focussed on nurse training, content and implementation of the intervention. Twenty-two PNs and 15 GPs participated in the interviews. The Quit with PN intervention was viewed positively. Most PNs were satisfied with the training and the materials provided. Some challenges in managing patient data and follow-up were identified. The Quit with PN intervention was acceptable to participating PNs and GPs. Issues to be addressed in the planning and wider implementation of future trials of nurse-led intervention in general practice include providing ongoing mentoring support, integration into practice management systems and strategies to promote greater collaboration in GPs and PN teams in general practice. The ongoing feasibility of the intervention was impacted by the funding model supporting PN employment and the competing demands on the PNs time. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

75 FR 29217 - Office of the Attorney General; Certification Process for State Capital Counsel Systems; Removal...

Science.gov (United States)

2010-05-25

... Office of the Attorney General; Certification Process for State Capital Counsel Systems; Removal of Final Rule AGENCY: Office of the Attorney General, Department of Justice. ACTION: Notice of proposed... the Attorney General has certified ``that [the] State has established a mechanism for providing...

Electoral Violence and Democratization Process in Nigeria: A Reference of 2011 and 2015 General Elections

Directory of Open Access Journals (Sweden)

Lawrence I. EDET

2015-09-01

Full Text Available The general account of Nigeria’s post-independence electoral processes has always been characterized by violence. Nigeria’s 2015 general elections marked the fifth multi-party elections in the country and the second handover of civilian administrations since the inception of the Fourth Republic democratic experiment in 1999. This account cannot be analyzed without issues of electoral violence. Electoral violence had been a permanent feature of Nigeria’s democratic process, except 2015 general elections where the international observers described as a “significant improvement” over the previous elections in terms of violence related cases. Electoral related violence in the country particularly in 2011 got to an unprecedented dimension resulting in destruction of lives and property worth millions of naira. This paper expatiates on electoral violence and its general implications on the democratization process in the country, with major emphasis on the 2011 and 2015 general elections. The paper argued that the high incidence of pre and post electoral violence in the country within the periods has to do with the way Nigerian politicians regard politics, weak political institutions and weak electoral management body as well as bias nature of the security agencies, etc. However, the paper examined the general implications of electoral violence on democratization process and how the country can handle the electoral process to avoid threats associated with the electoral violence. Archival analysis, which widely extracted data from newspapers, journals, workshop papers, books, as well as publications of non-governmental organizations was adopted for the study. The major significance of this study is to expose the negative implications associated with electoral violence and how it can be curbed. The position canvassed in this paper will serve as a useful political literature for political leaders, policy makers and the general reading public who

Eisenhart lift for higher derivative systems

Energy Technology Data Exchange (ETDEWEB)

Galajinsky, Anton, E-mail: galajin@tpu.ru; Masterov, Ivan, E-mail: masterov@tpu.ru

2017-02-10

The Eisenhart lift provides an elegant geometric description of a dynamical system of second order in terms of null geodesics of the Brinkmann-type metric. In this work, we attempt to generalize the Eisenhart method so as to encompass higher derivative models. The analysis relies upon Ostrogradsky's Hamiltonian. A consistent geometric description seems feasible only for a particular class of potentials. The scheme is exemplified by the Pais–Uhlenbeck oscillator.

Generalized Hofmann quantum process fidelity bounds for quantum filters

Science.gov (United States)

Sedlák, Michal; Fiurášek, Jaromír

2016-04-01

We propose and investigate bounds on the quantum process fidelity of quantum filters, i.e., probabilistic quantum operations represented by a single Kraus operator K . These bounds generalize the Hofmann bounds on the quantum process fidelity of unitary operations [H. F. Hofmann, Phys. Rev. Lett. 94, 160504 (2005), 10.1103/PhysRevLett.94.160504] and are based on probing the quantum filter with pure states forming two mutually unbiased bases. Determination of these bounds therefore requires far fewer measurements than full quantum process tomography. We find that it is particularly suitable to construct one of the probe bases from the right eigenstates of K , because in this case the bounds are tight in the sense that if the actual filter coincides with the ideal one, then both the lower and the upper bounds are equal to 1. We theoretically investigate the application of these bounds to a two-qubit optical quantum filter formed by the interference of two photons on a partially polarizing beam splitter. For an experimentally convenient choice of factorized input states and measurements we study the tightness of the bounds. We show that more stringent bounds can be obtained by more sophisticated processing of the data using convex optimization and we compare our methods for different choices of the input probe states.

75 FR 71353 - Office of the Attorney General; Certification Process for State Capital Counsel Systems; Removal...

Science.gov (United States)

2010-11-23

... the Attorney General; Certification Process for State Capital Counsel Systems; Removal of Final Rule... only if the Attorney General has certified ``that [the] State has established a mechanism for providing... State to qualify for the special habeas procedures, the Attorney General must determine that ``the State...

GENERAL ISSUES CONSIDERING BRAND EQUITY WITHIN THE NATION BRANDING PROCESS

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Denisa, COTÎRLEA

2014-11-01

Full Text Available The present work-paper was written in order to provide an overview of the intangible values that actively contribute to brand capital formation within the nation branding process; through this article, the author tried to emphasize the differences existent between brand capital and brand equity within the context of the nation branding process, which has became a widely approached subject both in the national and international literature. Also, the evolution of brand capital and brand equity was approached, in order to identify and explain their components and their role, by highlighting the entire process of their evolution under a sequence of steps scheme. The results of this paper are focused on the identification of a structured flowchart through which the process of nation branding -and the brand capital itself- are to be perceived as holistic concepts, integrator and inter-correlated ones, easily understood.The methodology used in order to write the present article resumes to all appropriate methods and techniques used for collecting and processing empirical data and information, respectively to observing, sorting, correlating, categorizing, comparing and analyzing data, so that the addressed theoretical elements could have been founded; in the center of the qualitative thematic research addressed in the present article lie general elements belonging to Romania's image and identity promotion.

Introduction of a pyramid guiding process for general musculoskeletal physical rehabilitation

Directory of Open Access Journals (Sweden)

Stark Timothy W

2006-06-01

Full Text Available Abstract Successful instruction of a complicated subject as Physical Rehabilitation demands organization. To understand principles and processes of such a field demands a hierarchy of steps to achieve the intended outcome. This paper is intended to be an introduction to a proposed pyramid scheme of general physical rehabilitation principles. The purpose of the pyramid scheme is to allow for a greater understanding for the student and patient. As the respected Food Guide Pyramid accomplishes, the student will further appreciate and apply supported physical rehabilitation principles and the patient will understand that there is a progressive method to their functional healing process.

General purpose graphic processing unit implementation of adaptive pulse compression algorithms

Science.gov (United States)

Cai, Jingxiao; Zhang, Yan

2017-07-01

This study introduces a practical approach to implement real-time signal processing algorithms for general surveillance radar based on NVIDIA graphical processing units (GPUs). The pulse compression algorithms are implemented using compute unified device architecture (CUDA) libraries such as CUDA basic linear algebra subroutines and CUDA fast Fourier transform library, which are adopted from open source libraries and optimized for the NVIDIA GPUs. For more advanced, adaptive processing algorithms such as adaptive pulse compression, customized kernel optimization is needed and investigated. A statistical optimization approach is developed for this purpose without needing much knowledge of the physical configurations of the kernels. It was found that the kernel optimization approach can significantly improve the performance. Benchmark performance is compared with the CPU performance in terms of processing accelerations. The proposed implementation framework can be used in various radar systems including ground-based phased array radar, airborne sense and avoid radar, and aerospace surveillance radar.

Adherence to diabetes care processes at general practices in the National Capital Region-Delhi, India

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Roopa Shivashankar

2016-01-01

Full Text Available Aim: To assess the level of adherence to diabetes care processes, and associated clinic and patient factors at general practices in Delhi, India. Methods: We interviewed physicians (n = 23 and patients with diabetes (n = 406, and reviewed patient charts at general practices (government = 5; private = 18. We examined diabetes care processes, specifically measurement of weight, blood pressure (BP, glycated hemoglobin (HbA1c, lipids, electrocardiogram, dilated eye, and a foot examination in the last one year. We analyzed clinic and patient factors associated with a number of care processes achieved using multilevel Poisson regression model. Results: The average number of clinic visits per patient was 8.8/year (standard deviation = 5.7, and physicians had access to patient's previous records in only 19.7% of patients. Dilated eye exam, foot exam, and electrocardiogram were completed in 7.4%, 15.1%, and 29.1% of patients, respectively. An estimated 51.7%, 88.4%, and 28.1% had ≥1 measurement of HbA1c, BP, and lipids, respectively. Private clinics, physician access to patient's previous records, use of nonphysicians, patient education, and the presence of diabetes complication were positively associated with a number of care processes in the multivariable model. Conclusion: Adherence to diabetes care processes was suboptimal. Encouraging implementation of quality improvement strategies like Chronic Care Model elements at general practices may improve diabetes care.

General distributions in process algebra

NARCIS (Netherlands)

Katoen, Joost P.; d' Argenio, P.R.; Brinksma, Hendrik; Hermanns, H.; Katoen, Joost P.

2001-01-01

This paper is an informal tutorial on stochastic process algebras, i.e., process calculi where action occurrences may be subject to a delay that is governed by a (mostly continuous) random variable. Whereas most stochastic process algebras consider delays determined by negative exponential

Profile of science process skills of Preservice Biology Teacher in General Biology Course

Science.gov (United States)

Susanti, R.; Anwar, Y.; Ermayanti

2018-04-01

This study aims to obtain portrayal images of science process skills among preservice biology teacher. This research took place in Sriwijaya University and involved 41 participants. To collect the data, this study used multiple choice test comprising 40 items to measure the mastery of science process skills. The data were then analyzed in descriptive manner. The results showed that communication aspect outperfomed the other skills with that 81%; while the lowest one was identifying variables and predicting (59%). In addition, basic science process skills was 72%; whereas for integrated skills was a bit lower, 67%. In general, the capability of doing science process skills varies among preservice biology teachers.

Generalized atomic processes for interaction of intense femtosecond XUV- and X-ray radiation with solids

International Nuclear Information System (INIS)

Deschaud, B.; Peyrusse, O.; Rosmej, F.B.

2014-01-01

Generalized atomic processes are proposed to establish a consistent description from the free-atom approach to the heated and even up to the cold solid. It is based on a rigorous introduction of the Fermi-Dirac statistics, Pauli blocking factors and on the respect of the principle of detailed balance via the introduction of direct and inverse processes. A probability formalism driven by the degeneracy of the free electrons enables to establish a link of atomic rates valid from the heated atom up to the cold solid. This allows to describe photoionization processes in atomic population kinetics and subsequent solid matter heating on a femtosecond time scale. The Auger effect is linked to the 3-body recombination via a generalized 3-body recombination that is identified as a key mechanism, along with the collisional ionization, that follows energy deposition by photoionization of inner shells when short, intense and high-energy radiation interacts with matter. Detailed simulations are carried out for aluminum that highlight the importance of the generalized approach. (authors)

Generalized random walk algorithm for the numerical modeling of complex diffusion processes

CERN Document Server

Vamos, C; Vereecken, H

2003-01-01

A generalized form of the random walk algorithm to simulate diffusion processes is introduced. Unlike the usual approach, at a given time all the particles from a grid node are simultaneously scattered using the Bernoulli repartition. This procedure saves memory and computing time and no restrictions are imposed for the maximum number of particles to be used in simulations. We prove that for simple diffusion the method generalizes the finite difference scheme and gives the same precision for large enough number of particles. As an example, simulations of diffusion in random velocity field are performed and the main features of the stochastic mathematical model are numerically tested.

Generalized random walk algorithm for the numerical modeling of complex diffusion processes

International Nuclear Information System (INIS)

Vamos, Calin; Suciu, Nicolae; Vereecken, Harry

2003-01-01

A generalized form of the random walk algorithm to simulate diffusion processes is introduced. Unlike the usual approach, at a given time all the particles from a grid node are simultaneously scattered using the Bernoulli repartition. This procedure saves memory and computing time and no restrictions are imposed for the maximum number of particles to be used in simulations. We prove that for simple diffusion the method generalizes the finite difference scheme and gives the same precision for large enough number of particles. As an example, simulations of diffusion in random velocity field are performed and the main features of the stochastic mathematical model are numerically tested

DNA Processing and Reassembly on General Purpose FPGA-based Development Boards

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SZÁSZ Csaba

2017-05-01

Full Text Available The great majority of researchers involved in microelectronics generally agree that many scientific challenges in life sciences have associated with them a powerful computational requirement that must be solved before scientific progress can be made. The current trend in Deoxyribonucleic Acid (DNA computing technologies is to develop special hardware platforms capable to provide the needed processing performance at lower cost. In this endeavor the FPGA-based (Field Programmable Gate Arrays configurations aimed to accelerate genome sequencing and reassembly plays a leading role. This paper emphasizes benefits and advantages using general purpose FPGA-based development boards in DNA reassembly applications beside the special hardware architecture solutions. An original approach is unfolded which outlines the versatility of high performance ready-to-use manufacturer development platforms endowed with powerful hardware resources fully optimized for high speed processing applications. The theoretical arguments are supported via an intuitive implementation example where the designer it is discharged from any hardware development effort and completely assisted in exclusive concentration only on software design issues providing greatly reduced application development cycles. The experiments prove that such boards available on the market are suitable to fulfill in all a wide range of DNA sequencing and reassembly applications.

Transition probabilities for general birth-death processes with applications in ecology, genetics, and evolution

Science.gov (United States)

Crawford, Forrest W.; Suchard, Marc A.

2011-01-01

A birth-death process is a continuous-time Markov chain that counts the number of particles in a system over time. In the general process with n current particles, a new particle is born with instantaneous rate λn and a particle dies with instantaneous rate μn. Currently no robust and efficient method exists to evaluate the finite-time transition probabilities in a general birth-death process with arbitrary birth and death rates. In this paper, we first revisit the theory of continued fractions to obtain expressions for the Laplace transforms of these transition probabilities and make explicit an important derivation connecting transition probabilities and continued fractions. We then develop an efficient algorithm for computing these probabilities that analyzes the error associated with approximations in the method. We demonstrate that this error-controlled method agrees with known solutions and outperforms previous approaches to computing these probabilities. Finally, we apply our novel method to several important problems in ecology, evolution, and genetics. PMID:21984359

General description of few-body break-up processes at threshold

International Nuclear Information System (INIS)

Barrachina, R.O.

2004-01-01

Full text: In this communication we present a general description of the behavior of fragmentation processes near threshold by analyzing the break-up into two, three and N bodies in steps of increasing complexity. In particular, we describe the effects produced by an N-body threshold behavior in N+1 body break-up processes, as it occurs in situations where one of the fragments acquires almost all the excess energy of the system. Furthermore, we relate the appearance of cusps and discontinuities in single-particle multiply differential cross sections to the threshold behavior of the remaining particles, and apply these ideas to different systems from atomic, molecular and nuclear collision physics. We finally show that, even though the study of ultracold collisions represents the direct way of gathering information on a break-up system near threshold, the analysis of high-energy collisions provides an alternative, and sometimes advantageous, approach

Cortical processes of speech illusions in the general population.

Science.gov (United States)

Schepers, E; Bodar, L; van Os, J; Lousberg, R

2016-10-18

There is evidence that experimentally elicited auditory illusions in the general population index risk for psychotic symptoms. As little is known about underlying cortical mechanisms of auditory illusions, an experiment was conducted to analyze processing of auditory illusions in a general population sample. In a follow-up design with two measurement moments (baseline and 6 months), participants (n = 83) underwent the White Noise task under simultaneous recording with a 14-lead EEG. An auditory illusion was defined as hearing any speech in a sound fragment containing white noise. A total number of 256 speech illusions (SI) were observed over the two measurements, with a high degree of stability of SI over time. There were 7 main effects of speech illusion on the EEG alpha band-the most significant indicating a decrease in activity at T3 (t = -4.05). Other EEG frequency bands (slow beta, fast beta, gamma, delta, theta) showed no significant associations with SI. SIs are characterized by reduced alpha activity in non-clinical populations. Given the association of SIs with psychosis, follow-up research is required to examine the possibility of reduced alpha activity mediating SIs in high risk and symptomatic populations.

A general-purpose process modelling framework for marine energy systems

International Nuclear Information System (INIS)

Dimopoulos, George G.; Georgopoulou, Chariklia A.; Stefanatos, Iason C.; Zymaris, Alexandros S.; Kakalis, Nikolaos M.P.

2014-01-01

Highlights: • Process modelling techniques applied in marine engineering. • Systems engineering approaches to manage the complexity of modern ship machinery. • General purpose modelling framework called COSSMOS. • Mathematical modelling of conservation equations and related chemical – transport phenomena. • Generic library of ship machinery component models. - Abstract: High fuel prices, environmental regulations and current shipping market conditions impose ships to operate in a more efficient and greener way. These drivers lead to the introduction of new technologies, fuels, and operations, increasing the complexity of modern ship energy systems. As a means to manage this complexity, in this paper we present the introduction of systems engineering methodologies in marine engineering via the development of a general-purpose process modelling framework for ships named as DNV COSSMOS. Shifting the focus from components – the standard approach in shipping- to systems, widens the space for optimal design and operation solutions. The associated computer implementation of COSSMOS is a platform that models, simulates and optimises integrated marine energy systems with respect to energy efficiency, emissions, safety/reliability and costs, under both steady-state and dynamic conditions. DNV COSSMOS can be used in assessment and optimisation of design and operation problems in existing vessels, new builds as well as new technologies. The main features and our modelling approach are presented and key capabilities are illustrated via two studies on the thermo-economic design and operation optimisation of a combined cycle system for large bulk carriers, and the transient operation simulation of an electric marine propulsion system

Generalized hardware post-processing technique for chaos-based pseudorandom number generators

KAUST Repository

Barakat, Mohamed L.

2013-06-01

This paper presents a generalized post-processing technique for enhancing the pseudorandomness of digital chaotic oscillators through a nonlinear XOR-based operation with rotation and feedback. The technique allows full utilization of the chaotic output as pseudorandom number generators and improves throughput without a significant area penalty. Digital design of a third-order chaotic system with maximum function nonlinearity is presented with verified chaotic dynamics. The proposed post-processing technique eliminates statistical degradation in all output bits, thus maximizing throughput compared to other processing techniques. Furthermore, the technique is applied to several fully digital chaotic oscillators with performance surpassing previously reported systems in the literature. The enhancement in the randomness is further examined in a simple image encryption application resulting in a better security performance. The system is verified through experiment on a Xilinx Virtex 4 FPGA with throughput up to 15.44 Gbit/s and logic utilization less than 0.84% for 32-bit implementations. © 2013 ETRI.

A general theory for radioactive processes in rare earth compounds

International Nuclear Information System (INIS)

Acevedo, R.; Meruane, T.

1998-01-01

The formal theory of radiative processes in centrosymmetric coordination compounds of the Ln X 3+ is a trivalent lanthanide ion and X -1 =Cl -1 , Br -1 ) is put forward based on a symmetry vibronic crystal field-ligand polarisation model. This research considers a truncated basis set for the intermediate states of the central metal ion and have derived general master equations to account for both the overall observed spectral intensities and the measured relative vibronic intensity distributions for parity forbidden but vibronically allowed electronic transitions. In addition, a procedure which includes the closure approximation over the intermediate electronic states is included in order to estimate quantitative crystal field contribution to the total transition dipole moments of various and selected electronic transitions. This formalism is both general and flexible and it may be employed in any electronic excitations involving f N type configurations for the rare earths in centrosymmetric co-ordination compounds in cubic environments and also in doped host crystals belonging to the space group Fm 3m. (author)

A Poisson process approximation for generalized K-5 confidence regions

Science.gov (United States)

Arsham, H.; Miller, D. R.

1982-01-01

One-sided confidence regions for continuous cumulative distribution functions are constructed using empirical cumulative distribution functions and the generalized Kolmogorov-Smirnov distance. The band width of such regions becomes narrower in the right or left tail of the distribution. To avoid tedious computation of confidence levels and critical values, an approximation based on the Poisson process is introduced. This aproximation provides a conservative confidence region; moreover, the approximation error decreases monotonically to 0 as sample size increases. Critical values necessary for implementation are given. Applications are made to the areas of risk analysis, investment modeling, reliability assessment, and analysis of fault tolerant systems.

General Self-Esteem of Adolescents from Ethnic Minorities in the Netherlands and the Reflected Appraisal Process.

Science.gov (United States)

Verkuyten, Maykel

1988-01-01

Examined lack of differences in general self-esteem between adolescents of ethnic minorities and Dutch adolescents, focusing on reflected appraisal process. Found significant relationship between general self-esteem and perceived evaluation of family members (and no such relationship with nonfamily members) for ethnic minority adolescents;…

General emotion processing in social anxiety disorder: neural issues of cognitive control.

Science.gov (United States)

Brühl, Annette Beatrix; Herwig, Uwe; Delsignore, Aba; Jäncke, Lutz; Rufer, Michael

2013-05-30

Anxiety disorders are characterized by deficient emotion regulation prior to and in anxiety-evoking situations. Patients with social anxiety disorder (SAD) have increased brain activation also during the anticipation and perception of non-specific emotional stimuli pointing to biased general emotion processing. In the current study we addressed the neural correlates of emotion regulation by cognitive control during the anticipation and perception of non-specific emotional stimuli in patients with SAD. Thirty-two patients with SAD underwent functional magnetic resonance imaging during the announced anticipation and perception of emotional stimuli. Half of them were trained and instructed to apply reality-checking as a control strategy, the others anticipated and perceived the stimuli. Reality checking significantly (pperception of negative emotional stimuli. The medial prefrontal cortex was comparably active in both groups (p>0.50). The results suggest that cognitive control in patients with SAD influences emotion processing structures, supporting the usefulness of emotion regulation training in the psychotherapy of SAD. In contrast to studies in healthy subjects, cognitive control was not associated with increased activation of prefrontal regions in SAD. This points to possibly disturbed general emotion regulating circuits in SAD. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Improvement of the Model of Enterprise Management Process on the Basis of General Management Functions

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Ruslan Skrynkovskyy

2017-12-01

Full Text Available The purpose of the article is to improve the model of the enterprise (institution, organization management process on the basis of general management functions. The graphic model of the process of management according to the process-structured management is presented. It has been established that in today's business environment, the model of the management process should include such general management functions as: 1 controlling the achievement of results; 2 planning based on the main goal; 3 coordination and corrective actions (in the system of organization of work and production; 4 action as a form of act (conscious, volitional, directed; 5 accounting system (accounting, statistical, operational-technical and managerial; 6 diagnosis (economic, legal with such subfunctions as: identification of the state and capabilities; analysis (economic, legal, systemic with argumentation; assessment of the state, trends and prospects of development. The prospect of further research in this direction is: 1 the formation of a system of interrelation of functions and management methods, taking into account the presented research results; 2 development of the model of effective and efficient communication business process of the enterprise.

Granular controls on the dispersion of bed load tracers

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Jerolmack, D. J.; Martin, R. L.; Phillips, C. B.

2014-12-01

Coarse particles are transported in a river as bed load, i.e., they move in frequent contact with and are supported by the granular bed. This movement is typically intermittent and may be described by a series of steps are rests, the distributions of which determine particle dispersion. Laboratory and field studies of bed load tracer dispersion have reported sub- and super-diffusive behavior, both of which have been successfully reproduced with stochastic transport models. Although researchers have invoked heavy-tailed step lengths as the cause of anomalous dispersion, most observations report thin-tailed distributions. Little attention has been paid to rest periods, and stochastic transport models have not been connected to the underlying mechanics of particle motion. Based on theoretical and experimental evidence, we argue that step lengths are thin-tailed and do not control the longterm dispersion of bed load tracers; they are determined by momentum balance between the fluid and solid. Using laboratory experiments with both marbles and natural sediments, we demonstrate that the rest time distribution is power law, and argue that this distribution controls asymptotic dispersion. Observed rest times far exceed any hydrodynamic timescale. Experiments reveal that rest times of deposited particles are governed by fluctuations in river bed elevation; in particular, the return time for the bed to scour to the base of a deposited particle. Stochastic fluctuations in bed elevation are describable by an Ornstein-Uhlenbeck (mean-reverting random walk) model that contains two parameters, which we show are directly related to the granular shear rate and range of bed elevation fluctuations, respectively. Combining these results with the theory of asymmetric random walks (particles only move downstream), we predict superdiffusive behavior that is in quantitative agreement with our observations of tracer dispersion in a natural river.

A rough multi-factor model of electricity spot prices

International Nuclear Information System (INIS)

Bennedsen, Mikkel

2017-01-01

We introduce a new continuous-time mathematical model of electricity spot prices which accounts for the most important stylized facts of these time series: seasonality, spikes, stochastic volatility, and mean reversion. Empirical studies have found a possible fifth stylized fact, roughness, and our approach explicitly incorporates this into the model of the prices. Our setup generalizes the popular Ornstein–Uhlenbeck-based multi-factor framework of and allows us to perform statistical tests to distinguish between an Ornstein–Uhlenbeck-based model and a rough model. Further, through the multi-factor approach we account for seasonality and spikes before estimating – and making inference on – the degree of roughness. This is novel in the literature and we present simulation evidence showing that these precautions are crucial for accurate estimation. Lastly, we estimate our model on recent data from six European energy exchanges and find statistical evidence of roughness in five out of six markets. As an application of our model, we show how, in these five markets, a rough component improves short term forecasting of the prices. - Highlights: • Statistical modeling of electricity spot prices • Multi-factor decomposition • Roughness • Electricity price forecasting

Audit and account billing process in a private general hospital: a case study

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Raquel Silva Bicalho Zunta

2017-12-01

Full Text Available Our study aimed to map, describe and, validate the audit, account billing and billing reports processes in a large, private general hospital.  An exploratory, descriptive, case report study. We conducted non-participatory observation moments in Internal Audit Sectors and  Billing Reports from the hospital, aiming to map the processes which were the study objects. The data obtained was validated by internal and external audit specialists in hospital bills. The described and illustrated processes in three flow-charts favor professionals to rationalize their activities and the time spent in hospital billing, avoiding or minimizing the occurrence of flaws and, generating more effective financial results. The mapping, the description and the audit validation process and billing and, the billing reports propitiated more visibility and legitimacy to actions developed by auditor nurses.

Improving the training process of highly skilled bodybuilders in the preparatory period, general preparatory phase

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Olexandr Tyhorskyy

2015-08-01

Full Text Available Purpose: to improve the method of training highly skilled bodybuilders during the general preparatory phase. Material and Methods: the study involved eight highly skilled athletes, members of the team of Ukraine on bodybuilding. Results: comparative characteristics of the most commonly used methods of training process in bodybuilding. Developed and substantiated the optimal method of training highly skilled bodybuilders during the general preparatory phase of the preparatory period, which can increase body weight through muscle athletes component. Conclusions: based on studies, recommended the optimum method of training highly skilled bodybuilders depending on mezotsykles and microcycles general preparatory phase

How does processing affect storage in working memory tasks? Evidence for both domain-general and domain-specific effects.

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Jarrold, Christopher; Tam, Helen; Baddeley, Alan D; Harvey, Caroline E

2011-05-01

Two studies that examine whether the forgetting caused by the processing demands of working memory tasks is domain-general or domain-specific are presented. In each, separate groups of adult participants were asked to carry out either verbal or nonverbal operations on exactly the same processing materials while maintaining verbal storage items. The imposition of verbal processing tended to produce greater forgetting even though verbal processing operations took no longer to complete than did nonverbal processing operations. However, nonverbal processing did cause forgetting relative to baseline control conditions, and evidence from the timing of individuals' processing responses suggests that individuals in both processing groups slowed their responses in order to "refresh" the memoranda. Taken together the data suggest that processing has a domain-general effect on working memory performance by impeding refreshment of memoranda but can also cause effects that appear domain-specific and that result from either blocking of rehearsal or interference.

Generalized Fractional Processes with Long Memory and Time Dependent Volatility Revisited

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M. Shelton Peiris

2016-09-01

Full Text Available In recent years, fractionally-differenced processes have received a great deal of attention due to their flexibility in financial applications with long-memory. This paper revisits the class of generalized fractionally-differenced processes generated by Gegenbauer polynomials and the ARMA structure (GARMA with both the long-memory and time-dependent innovation variance. We establish the existence and uniqueness of second-order solutions. We also extend this family with innovations to follow GARCH and stochastic volatility (SV. Under certain regularity conditions, we give asymptotic results for the approximate maximum likelihood estimator for the GARMA-GARCH model. We discuss a Monte Carlo likelihood method for the GARMA-SV model and investigate finite sample properties via Monte Carlo experiments. Finally, we illustrate the usefulness of this approach using monthly inflation rates for France, Japan and the United States.

A national general pediatric clerkship curriculum: the process of development and implementation.

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Olson, A L; Woodhead, J; Berkow, R; Kaufman, N M; Marshall, S G

2000-07-01

To describe a new national general pediatrics clerkship curriculum, the development process that built national support for its use, and current progress in implementing the curriculum in pediatric clerkships at US allopathic medical schools. CURRICULUM DEVELOPMENT: A curriculum project team of pediatric clerkship directors and an advisory committee representing professional organizations invested in pediatric student education developed the format and content in collaboration with pediatric educators from the Council on Medical Student Education in Pediatrics (COMSEP) and the Ambulatory Pediatric Association (APA). An iterative process or review by clerkship directors, pediatric departmental chairs, and students finalized the content and built support for the final product. The national dissemination process resulted in consensus among pediatric educators that this curriculum should be used as the national curricular guideline for clerkships. MONITORING IMPLEMENTATION: Surveys were mailed to all pediatric clerkship directors before dissemination (November 1994), and in the first and third academic years after national dissemination (March 1996 and September 1997). The 3 surveys assessed schools' implementation of specific components of the curriculum. The final survey also assessed ways the curriculum was used and barriers to implementation. The final curriculum provided objectives and competencies for attitudes, skills, and 18 knowledge areas of general pediatrics. A total of 216 short clinical cases were also provided as an alternative learning method. An accompanying resource manual provided suggested strategies for implementation, teaching, and evaluation. A total of 103 schools responded to survey 1; 84 schools to survey 2; and 85 schools responded to survey 3 from the 125 medical schools surveyed. Before dissemination, 16% of schools were already using the clinical cases. In the 1995-1996 academic year, 70% of schools were using some or all of the curricular

Poisson-process generalization for the trading waiting-time distribution in a double-auction mechanism

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Cincotti, Silvano; Ponta, Linda; Raberto, Marco; Scalas, Enrico

2005-05-01

In this paper, empirical analyses and computational experiments are presented on high-frequency data for a double-auction (book) market. Main objective of the paper is to generalize the order waiting time process in order to properly model such empirical evidences. The empirical study is performed on the best bid and best ask data of 7 U.S. financial markets, for 30-stock time series. In particular, statistical properties of trading waiting times have been analyzed and quality of fits is evaluated by suitable statistical tests, i.e., comparing empirical distributions with theoretical models. Starting from the statistical studies on real data, attention has been focused on the reproducibility of such results in an artificial market. The computational experiments have been performed within the Genoa Artificial Stock Market. In the market model, heterogeneous agents trade one risky asset in exchange for cash. Agents have zero intelligence and issue random limit or market orders depending on their budget constraints. The price is cleared by means of a limit order book. The order generation is modelled with a renewal process. Based on empirical trading estimation, the distribution of waiting times between two consecutive orders is modelled by a mixture of exponential processes. Results show that the empirical waiting-time distribution can be considered as a generalization of a Poisson process. Moreover, the renewal process can approximate real data and implementation on the artificial stocks market can reproduce the trading activity in a realistic way.

A Dirichlet process mixture of generalized Dirichlet distributions for proportional data modeling.

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Bouguila, Nizar; Ziou, Djemel

2010-01-01

In this paper, we propose a clustering algorithm based on both Dirichlet processes and generalized Dirichlet distribution which has been shown to be very flexible for proportional data modeling. Our approach can be viewed as an extension of the finite generalized Dirichlet mixture model to the infinite case. The extension is based on nonparametric Bayesian analysis. This clustering algorithm does not require the specification of the number of mixture components to be given in advance and estimates it in a principled manner. Our approach is Bayesian and relies on the estimation of the posterior distribution of clusterings using Gibbs sampler. Through some applications involving real-data classification and image databases categorization using visual words, we show that clustering via infinite mixture models offers a more powerful and robust performance than classic finite mixtures.

76 FR 4360 - Guidance for Industry on Process Validation: General Principles and Practices; Availability

Science.gov (United States)

2011-01-25

... and Development (HFM-40), Center for Biologics Evaluation and Research (CBER), Food and Drug...] Guidance for Industry on Process Validation: General Principles and Practices; Availability AGENCY: Food... of Drug Information, Center for Drug Evaluation and Research, Food and Drug Administration, 10903 New...

A novel theory: biological processes mostly involve two types of mediators, namely general and specific mediators Endogenous small radicals such as superoxide and nitric oxide may play a role of general mediator in biological processes.

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Mo, Jian

2005-01-01

A great number of papers have shown that free radicals as well as bioactive molecules can play a role of mediator in a wide spectrum of biological processes, but the biological actions and chemical reactivity of the free radicals are quite different from that of the bioactive molecules, and that a wide variety of bioactive molecules can be easily modified by free radicals due to having functional groups sensitive to redox, and the significance of the interaction between the free radicals and the bioactive molecules in biological processes has been confirmed by the results of some in vitro and in vivo studies. Based on these evidence, this article presented a novel theory about the mediators of biological processes. The essentials of the theory are: (a) mediators of biological processes can be classified into general and specific mediators; the general mediators include two types of free radicals, namely superoxide and nitric oxide; the specific mediators include a wide variety of bioactive molecules, such as specific enzymes, transcription factors, cytokines and eicosanoids; (b) a general mediator can modify almost any class of the biomolecules, and thus play a role of mediator in nearly every biological process via diverse mechanisms; a specific mediator always acts selectively on certain classes of the biomolecules, and may play a role of mediator in different biological processes via a same mechanism; (c) biological processes are mostly controlled by networks of their mediators, so the free radicals can regulate the last consequence of a biological process by modifying some types of the bioactive molecules, or in cooperation with these bioactive molecules; the biological actions of superoxide and nitric oxide may be synergistic or antagonistic. According to this theory, keeping the integrity of these networks and the balance between the free radicals and the bioactive molecules as well as the balance between the free radicals and the free radical scavengers

Analytic solution of integral equations for molecular fluids

International Nuclear Information System (INIS)

Cummings, P.T.

1984-01-01

We review some recent progress in the analytic solution of integral equations for molecular fluids. The site-site Ornstein-Zernike (SSOZ) equation with approximate closures appropriate to homonuclear diatomic fluids both with and without attractive dispersion-like interactions has recently been solved in closed form analytically. In this paper, the close relationship between the SSOZ equation for homonuclear dumbells and the usual Ornstein-Zernike (OZ) equation for atomic fluids is carefully elucidated. This relationship is a key motivation for the analytic solutions of the SSOZ equation that have been obtained to date. (author)

ABOUT THE GENERAL CONCEPT OF THE UNIVERSAL STORAGE SYSTEM AND PRACTICE-ORIENTED DATA PROCESSING

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L. V. Rudikova

2017-01-01

Full Text Available Approaches evolution and concept of data accumulation in warehouse and subsequent Data Mining use is perspective due to the fact that, Belarusian segment of the same IT-developments is organizing. The article describes the general concept for creation a system of storage and practice-oriented data analysis, based on the data warehousing technology. The main aspect in universal system design on storage layer and working with data is approach uses extended data warehouse, based on universal platform of stored data, which grants access to storage and subsequent data analysis different structure and subject domains have compound’s points (nodes and extended functional with data structure choice option for data storage and subsequent intrasystem integration. Describe the universal system general architecture of storage and analysis practice-oriented data, structural elements. Main components of universal system for storage and processing practice-oriented data are: online data sources, ETL-process, data warehouse, subsystem of analysis, users. An important place in the system is analytical processing of data, information search, document’s storage and providing a software interface for accessing the functionality of the system from the outside. An universal system based on describing concept will allow collection information of different subject domains, get analytical summaries, do data processing and apply appropriate Data Mining methods and algorithms.

Understanding the process of patient satisfaction with nurse-led chronic disease management in general practice.

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Mahomed, Rosemary; St John, Winsome; Patterson, Elizabeth

2012-11-01

  To investigate the process of patient satisfaction with nurse-led chronic disease management in Australian general practice.   Nurses working in the primary care context of general practice, referred to as practice nurses, are expanding their role in chronic disease management; this is relatively new to Australia. Therefore, determining patient satisfaction with this trend is pragmatically and ethically important. However, the concept of patient satisfaction is not well understood particularly in relation to care provided by practice nurses.   A grounded theory study underpinned by a relativist ontological position and a relativist epistemology.   Grounded theory was used to develop a theory from data collected through in-depth interviews with 38 participants between November 2007-April 2009. Participants were drawn from a larger project that trialled a practice nurse-led, collaborative model of chronic disease management in three Australian general practices. Theoretical sampling, data collection, and analysis were conducted concurrently consistent with grounded theory methods.   Patients undergo a cyclical process of Navigating Care involving three stages, Determining Care Needs, Forming Relationship, and Having Confidence. The latter two processes are inter-related and a feedback loop from them informs subsequent cycles of Determining Care Needs. If any of these steps fails to develop adequately, patients are likely to opt out of nurse-led care.   Navigating Care explains how and why time, communication, continuity, and trust in general practitioners and nurses are important to patient satisfaction. It can be used in identifying suitable patients for practice nurse-led care and to inform the practice and organization of practice nurse-led care to enhance patient satisfaction. © 2012 Blackwell Publishing Ltd.

Kerr-de Sitter spacetime, Penrose process, and the generalized area theorem

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Bhattacharya, Sourav

2018-04-01

We investigate various aspects of energy extraction via the Penrose process in the Kerr-de Sitter spacetime. We show that the increase in the value of a positive cosmological constant, Λ , always reduces the efficiency of this process. The Kerr-de Sitter spacetime has two ergospheres associated with the black hole and the cosmological event horizons. We prove by analyzing turning points of the trajectory that the Penrose process in the cosmological ergoregion is never possible. We next show that in this process both the black hole and cosmological event horizons' areas increase, and the latter becomes possible when the particle coming from the black hole ergoregion escapes through the cosmological event horizon. We identify a new, local mass function instead of the mass parameter, to prove this generalized area theorem. This mass function takes care of the local spacetime energy due to the cosmological constant as well, including that which arises due to the frame-dragging effect due to spacetime rotation. While the current observed value of Λ is quite small, its effect in this process could be considerable in the early Universe scenario where its value is much larger, where the two horizons could have comparable sizes. In particular, the various results we obtain here are also evaluated in a triply degenerate limit of the Kerr-de Sitter spacetime we find, in which radial values of the inner, the black hole and the cosmological event horizons are nearly coincident.

General Purpose Graphics Processing Unit Based High-Rate Rice Decompression and Reed-Solomon Decoding

Energy Technology Data Exchange (ETDEWEB)

Loughry, Thomas A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-02-01

As the volume of data acquired by space-based sensors increases, mission data compression/decompression and forward error correction code processing performance must likewise scale. This competency development effort was explored using the General Purpose Graphics Processing Unit (GPGPU) to accomplish high-rate Rice Decompression and high-rate Reed-Solomon (RS) decoding at the satellite mission ground station. Each algorithm was implemented and benchmarked on a single GPGPU. Distributed processing across one to four GPGPUs was also investigated. The results show that the GPGPU has considerable potential for performing satellite communication Data Signal Processing, with three times or better performance improvements and up to ten times reduction in cost over custom hardware, at least in the case of Rice Decompression and Reed-Solomon Decoding.

Adolescents with Developmental Dyscalculia Do Not Have a Generalized Magnitude Deficit - Processing of Discrete and Continuous Magnitudes.

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McCaskey, Ursina; von Aster, Michael; O'Gorman Tuura, Ruth; Kucian, Karin

2017-01-01

The link between number and space has been discussed in the literature for some time, resulting in the theory that number, space and time might be part of a generalized magnitude system. To date, several behavioral and neuroimaging findings support the notion of a generalized magnitude system, although contradictory results showing a partial overlap or separate magnitude systems are also found. The possible existence of a generalized magnitude processing area leads to the question how individuals with developmental dyscalculia (DD), known for deficits in numerical-arithmetical abilities, process magnitudes. By means of neuropsychological tests and functional magnetic resonance imaging (fMRI) we aimed to examine the relationship between number and space in typical and atypical development. Participants were 16 adolescents with DD (14.1 years) and 14 typically developing (TD) peers (13.8 years). In the fMRI paradigm participants had to perform discrete (arrays of dots) and continuous magnitude (angles) comparisons as well as a mental rotation task. In the neuropsychological tests, adolescents with dyscalculia performed significantly worse in numerical and complex visuo-spatial tasks. However, they showed similar results to TD peers when making discrete and continuous magnitude decisions during the neuropsychological tests and the fMRI paradigm. A conjunction analysis of the fMRI data revealed commonly activated higher order visual (inferior and middle occipital gyrus) and parietal (inferior and superior parietal lobe) magnitude areas for the discrete and continuous magnitude tasks. Moreover, no differences were found when contrasting both magnitude processing conditions, favoring the possibility of a generalized magnitude system. Group comparisons further revealed that dyscalculic subjects showed increased activation in domain general regions, whilst TD peers activate domain specific areas to a greater extent. In conclusion, our results point to the existence of a

SELECTION OF BURST-LIKE TRANSIENTS AND STOCHASTIC VARIABLES USING MULTI-BAND IMAGE DIFFERENCING IN THE PAN-STARRS1 MEDIUM-DEEP SURVEY

International Nuclear Information System (INIS)

Kumar, S.; Gezari, S.; Heinis, S.; Chornock, R.; Berger, E.; Soderberg, A.; Stubbs, C. W.; Kirshner, R. P.; Rest, A.; Huber, M. E.; Narayan, G.; Marion, G. H.; Burgett, W. S.; Foley, R. J.; Scolnic, D.; Riess, A. G.; Lawrence, A.; Smartt, S. J.; Smith, K.; Wood-Vasey, W. M.

2015-01-01

We present a novel method for the light-curve characterization of Pan-STARRS1 Medium Deep Survey (PS1 MDS) extragalactic sources into stochastic variables (SVs) and burst-like (BL) transients, using multi-band image-differencing time-series data. We select detections in difference images associated with galaxy hosts using a star/galaxy catalog extracted from the deep PS1 MDS stacked images, and adopt a maximum a posteriori formulation to model their difference-flux time-series in four Pan-STARRS1 photometric bands g P1 , r P1 , i P1 , and z P1 . We use three deterministic light-curve models to fit BL transients; a Gaussian, a Gamma distribution, and an analytic supernova (SN) model, and one stochastic light-curve model, the Ornstein-Uhlenbeck process, in order to fit variability that is characteristic of active galactic nuclei (AGNs). We assess the quality of fit of the models band-wise and source-wise, using their estimated leave-out-one cross-validation likelihoods and corrected Akaike information criteria. We then apply a K-means clustering algorithm on these statistics, to determine the source classification in each band. The final source classification is derived as a combination of the individual filter classifications, resulting in two measures of classification quality, from the averages across the photometric filters of (1) the classifications determined from the closest K-means cluster centers, and (2) the square distances from the clustering centers in the K-means clustering spaces. For a verification set of AGNs and SNe, we show that SV and BL occupy distinct regions in the plane constituted by these measures. We use our clustering method to characterize 4361 extragalactic image difference detected sources, in the first 2.5 yr of the PS1 MDS, into 1529 BL, and 2262 SV, with a purity of 95.00% for AGNs, and 90.97% for SN based on our verification sets. We combine our light-curve classifications with their nuclear or off-nuclear host galaxy offsets, to

Nonlinear dynamics in micromechanical and nanomechanical resonators and oscillators

Science.gov (United States)

Dunn, Tyler

In recent years, the study of nonlinear dynamics in microelectromechanical and nanoelectromechanical systems (MEMS and NEMS) has attracted considerable attention, motivated by both fundamental and practical interests. One example is the phenomenon of stochastic resonance. Previous measurements have established the presence of this counterintuitive effect in NEMS, showing that certain amounts of white noise can effectively amplify weak switching signals in nanomechanical memory elements and switches. However, other types of noise, particularly noises with 1/falpha spectra, also bear relevance in these and many other systems. At a more fundamental level, the role which noise color plays in stochastic resonance remains an open question in the field. To these ends, this work presents systematic measurements of stochastic resonance in a nanomechanical resonator using 1/f alpha and Ornstein-Uhlenbeck noise types. All of the studied noise spectra induce stochastic resonance, proving that colored noise can also be beneficial; however, stronger noise correlations suppress the effect, decreasing the maximum signal-to-noise ratio and increasing the optimal noise intensity. Evidence suggests that 1/falpha noise spectra with increasing noise color lead to increasingly asymmetric switching, reducing the achievable amplification. Another manifestly nonlinear effect anticipated in these systems is modal coupling. Measurements presented here demonstrate interactions between various mode types on a wide scale, providing the first reported observations of coupling in bulk longitudinal modes of MEMS. As a result of anharmonic elastic effects, each mode shifts in frequency by an amount proportional to the squared displacement (or energy) of a coupled mode. Since all resonator modes couple in this manner, these effects enable nonlinear measurement of energy and mechanical nonlinear signal processing across a wide range of frequencies. Finally, while these experiments address nonlinear

Identifying critical success factors for designing selection processes into postgraduate specialty training: the case of UK general practice.

Science.gov (United States)

Plint, Simon; Patterson, Fiona

2010-06-01

The UK national recruitment process into general practice training has been developed over several years, with incremental introduction of stages which have been piloted and validated. Previously independent processes, which encouraged multiple applications and produced inconsistent outcomes, have been replaced by a robust national process which has high reliability and predictive validity, and is perceived to be fair by candidates and allocates applicants equitably across the country. Best selection practice involves a job analysis which identifies required competencies, then designs reliable assessment methods to measure them, and over the long term ensures that the process has predictive validity against future performance. The general practitioner recruitment process introduced machine markable short listing assessments for the first time in the UK postgraduate recruitment context, and also adopted selection centre workplace simulations. The key success factors have been identified as corporate commitment to the goal of a national process, with gradual convergence maintaining locus of control rather than the imposition of change without perceived legitimate authority.

The Green-Kubo formula for general Markov processes with a continuous time parameter

International Nuclear Information System (INIS)

Yang Fengxia; Liu Yong; Chen Yong

2010-01-01

For general Markov processes, the Green-Kubo formula is shown to be valid under a mild condition. A class of stochastic evolution equations on a separable Hilbert space and three typical infinite systems of locally interacting diffusions on Z d (irreversible in most cases) are shown to satisfy the Green-Kubo formula, and the Einstein relations for these stochastic evolution equations are shown explicitly as a corollary.

Communication: An exact bound on the bridge function in integral equation theories.

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Kast, Stefan M; Tomazic, Daniel

2012-11-07

We show that the formal solution of the general closure relation occurring in Ornstein-Zernike-type integral equation theories in terms of the Lambert W function leads to an exact relation between the bridge function and correlation functions, most notably to an inequality that bounds possible bridge values. The analytical results are illustrated on the example of the Lennard-Jones fluid for which the exact bridge function is known from computer simulations under various conditions. The inequality has consequences for the development of bridge function models and rationalizes numerical convergence issues.

Theoretical method for determining particle distribution functions of classical systems

International Nuclear Information System (INIS)

Johnson, E.

1980-01-01

An equation which involves the triplet distribution function and the three-particle direct correlation function is obtained. This equation was derived using an analogue of the Ornstein--Zernike equation. The new equation is used to develop a variational method for obtaining the triplet distribution function of uniform one-component atomic fluids from the pair distribution function. The variational method may be used with the first and second equations in the YBG hierarchy to obtain pair and triplet distribution functions. It should be easy to generalize the results to the n-particle distribution function

Bio-inspired Artificial Intelligence: А Generalized Net Model of the Regularization Process in MLP

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Stanimir Surchev

2013-10-01

Full Text Available Many objects and processes inspired by the nature have been recreated by the scientists. The inspiration to create a Multilayer Neural Network came from human brain as member of the group. It possesses complicated structure and it is difficult to recreate, because of the existence of too many processes that require different solving methods. The aim of the following paper is to describe one of the methods that improve learning process of Artificial Neural Network. The proposed generalized net method presents Regularization process in Multilayer Neural Network. The purpose of verification is to protect the neural network from overfitting. The regularization is commonly used in neural network training process. Many methods of verification are present, the subject of interest is the one known as Regularization. It contains function in order to set weights and biases with smaller values to protect from overfitting.

Shore Shapers: Introducing children and the general public to biogeomorphological processes and geodiversity

Science.gov (United States)

Naylor, Larissa; Coombes, Martin; Sewell, Jack; White, Anissia

2014-05-01

Coastal processes shape the coast into a variety of eye-catching and enticing landforms that attract people to marvel at, relax and enjoy coastal geomorphology. Field guides to explain these processes (and the geodiversity that results) to the general public and children are few and far between. In contrast, there is a relative wealth of resources and organised activities introducing people to coastal wildlife, especially on rocky shores. These biological resources typically focus on the biology and climatic controls on their distribution, rather than how the biology interacts with its physical habitat. As an outcome of two recent rock coast biogeomorphology projects (www.biogeomorph.org/coastal/coastaldefencedbiodiversity and www.biogeomorph.org/coastal/bioprotection ), we produced the first known guide to understanding how biogeomorphological processes help create coastal landforms. The 'Shore Shapers' guide (www.biogeomorph.org/coastal/shoreshapers) is designed to: a) bring biotic-geomorphic interactions to life and b) introduce some of the geomorphological and geological controls on biogeomorphic processes and landform development. The guide provides scientific information in an accessible and interactive way - to help sustain children's interest and extend their learning. We tested a draft version of our guide with children, the general public and volunteers on rocky shore rambles using social science techniques and of 74 respondents, 75.6% were more interested in understanding how rock pools (i.e. coastal landforms) develop after seeing the guide. Respondents' opinions about key bioprotective species also changed as a result of seeing the guide - 58% of people found barnacles unattractive before they saw the guide whilst 36% of respondents were more interested in barnacles after seeing the guide. These results demonstrate that there is considerable interest in more educational materials on coastal biogeomorphology and geodiversity.

A Business Process Management System based on a General Optimium Criterion

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Vasile MAZILESCU

2009-01-01

Full Text Available Business Process Management Systems (BPMS provide a broadrange of facilities to manage operational business processes. These systemsshould provide support for the complete Business Process Management (BPMlife-cycle [16]: (redesign, configuration, execution, control, and diagnosis ofprocesses. BPMS can be seen as successors of Workflow Management (WFMsystems. However, already in the seventies people were working on officeautomation systems which are comparable with today’s WFM systems.Recently, WFM vendors started to position their systems as BPMS. Our paper’sgoal is a proposal for a Tasks-to-Workstations Assignment Algorithm (TWAAfor assembly lines which is a special implementation of a stochastic descenttechnique, in the context of BPMS, especially at the control level. Both cases,single and mixed-model, are treated. For a family of product models having thesame generic structure, the mixed-model assignment problem can be formulatedthrough an equivalent single-model problem. A general optimum criterion isconsidered. As the assembly line balancing, this kind of optimisation problemleads to a graph partitioning problem meeting precedence and feasibilityconstraints. The proposed definition for the "neighbourhood" function involvesan efficient way for treating the partition and precedence constraints. Moreover,the Stochastic Descent Technique (SDT allows an implicit treatment of thefeasibility constraint. The proposed algorithm converges with probability 1 toan optimal solution.

Ions cross-B collisional diffusion and electromagnetic wave scattering

International Nuclear Information System (INIS)

Tomchuk, B.P.; Gresillon, D.

2000-01-01

The calculation is presented of the averaged quadratic displacement of a collisional charged particle in a magnetic field. This calculation is used to obtain the statistical presentation of the electromagnetic field scattered by these particles. These results extend the previous calculations that were restricted to non-magnetized particles (Ornstein equation, Einstein diffusion, etc.). In addition this calculation foresees effects that are absent of the Ornstein equation: a modulation of the averaged quadratic displacement function at the cyclotron frequency and a maximum of the Cross-B diffusion coefficient when the cyclotron frequency is equal to the collision frequency (Bohm diffusion)

Attention allocation: Relationships to general working memory or specific language processing.

Science.gov (United States)

Archibald, Lisa M D; Levee, Tyler; Olino, Thomas

2015-11-01

Attention allocation, updating working memory, and language processing are interdependent cognitive tasks related to the focused direction of limited resources, refreshing and substituting information in the current focus of attention, and receiving/sending verbal communication, respectively. The current study systematically examined the relationship among executive attention, working memory executive skills, and language abilities while adjusting for individual differences in short-term memory. School-age children completed a selective attention task requiring them to recall whether a presented shape was in the same place as a previous target shape shown in an array imposing a low or high working memory load. Results revealed a selective attention cost when working above but not within memory span capacity. Measures of general working memory were positively related to overall task performance, whereas language abilities were related to response time. In particular, higher language skills were associated with faster responses under low load conditions. These findings suggest that attentional control and storage demands have an additive impact on working memory resources but provide only limited evidence for a domain-general mechanism in language learning. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

A Latent Variable Analysis of Working Memory Capacity, Short-Term Memory Capacity, Processing Speed, and General Fluid Intelligence.

Science.gov (United States)

Conway, Andrew R. A.; Cowan, Nelsin; Bunting, Michael F.; Therriault, David J.; Minkoff, Scott R. B.

2002-01-01

Studied the interrelationships among general fluid intelligence, short-term memory capacity, working memory capacity, and processing speed in 120 young adults and used structural equation modeling to determine the best predictor of general fluid intelligence. Results suggest that working memory capacity, but not short-term memory capacity or…

Adolescents with Developmental Dyscalculia Do Not Have a Generalized Magnitude Deficit – Processing of Discrete and Continuous Magnitudes

Science.gov (United States)

McCaskey, Ursina; von Aster, Michael; O’Gorman Tuura, Ruth; Kucian, Karin

2017-01-01

The link between number and space has been discussed in the literature for some time, resulting in the theory that number, space and time might be part of a generalized magnitude system. To date, several behavioral and neuroimaging findings support the notion of a generalized magnitude system, although contradictory results showing a partial overlap or separate magnitude systems are also found. The possible existence of a generalized magnitude processing area leads to the question how individuals with developmental dyscalculia (DD), known for deficits in numerical-arithmetical abilities, process magnitudes. By means of neuropsychological tests and functional magnetic resonance imaging (fMRI) we aimed to examine the relationship between number and space in typical and atypical development. Participants were 16 adolescents with DD (14.1 years) and 14 typically developing (TD) peers (13.8 years). In the fMRI paradigm participants had to perform discrete (arrays of dots) and continuous magnitude (angles) comparisons as well as a mental rotation task. In the neuropsychological tests, adolescents with dyscalculia performed significantly worse in numerical and complex visuo-spatial tasks. However, they showed similar results to TD peers when making discrete and continuous magnitude decisions during the neuropsychological tests and the fMRI paradigm. A conjunction analysis of the fMRI data revealed commonly activated higher order visual (inferior and middle occipital gyrus) and parietal (inferior and superior parietal lobe) magnitude areas for the discrete and continuous magnitude tasks. Moreover, no differences were found when contrasting both magnitude processing conditions, favoring the possibility of a generalized magnitude system. Group comparisons further revealed that dyscalculic subjects showed increased activation in domain general regions, whilst TD peers activate domain specific areas to a greater extent. In conclusion, our results point to the existence of a

The misconception of mean-reversion

International Nuclear Information System (INIS)

Eliazar, Iddo I; Cohen, Morrel H

2012-01-01

The notion of random motion in a potential well is elemental in the physical sciences and beyond. Quantitatively, this notion is described by reverting diffusions—asymptotically stationary diffusion processes which are simultaneously (i) driven toward a reversion level by a deterministic force, and (ii) perturbed off the reversion level by a random white noise. The archetypal example of reverting diffusions is the Ornstein–Uhlenbeck process, which is mean-reverting. In this paper we analyze reverting diffusions and establish that: (i) if the magnitude of the perturbing noise is constant then the diffusion's stationary density is unimodal and the diffusion is mode-reverting; (ii) if the magnitude of the perturbing noise is non-constant then, in general, neither is the diffusion's stationary density unimodal, nor is the diffusion mode-reverting. In the latter case we further establish a result asserting when unimodality and mode-reversion do hold. In particular, we demonstrate that the notion of mean-reversion, which is fundamental in economics and finance, is a misconception—as mean-reversion is an exception rather than the norm. (fast track communication)

17 CFR 279.4 - Form ADV-NR, appointment of agent for service of process by non-resident general partner and non...

Science.gov (United States)

2010-04-01

... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Form ADV-NR, appointment of agent for service of process by non-resident general partner and non-resident managing agent of an... agent for service of process by non-resident general partner and non-resident managing agent of an...

Attorney General forces Infectious Diseases Society of America to redo Lyme guidelines due to flawed development process.

Science.gov (United States)

Johnson, L; Stricker, R B

2009-05-01

Lyme disease is one of the most controversial illnesses in the history of medicine. In 2006 the Connecticut Attorney General launched an antitrust investigation into the Lyme guidelines development process of the Infectious Diseases Society of America (IDSA). In a recent settlement with IDSA, the Attorney General noted important commercial conflicts of interest and suppression of scientific evidence that had tainted the guidelines process. This paper explores two broad ethical themes that influenced the IDSA investigation. The first is the growing problem of conflicts of interest among guidelines developers, and the second is the increasing centralisation of medical decisions by insurance companies, which use treatment guidelines as a means of controlling the practices of individual doctors and denying treatment for patients. The implications of the first-ever antitrust investigation of medical guidelines and the proposed model to remediate the tainted IDSA guidelines process are also discussed.

The Generalized Support Software (GSS) Domain Engineering Process: An Object-Oriented Implementation and Reuse Success at Goddard Space Flight Center

Science.gov (United States)

Condon, Steven; Hendrick, Robert; Stark, Michael E.; Steger, Warren

1997-01-01

The Flight Dynamics Division (FDD) of NASA's Goddard Space Flight Center (GSFC) recently embarked on a far-reaching revision of its process for developing and maintaining satellite support software. The new process relies on an object-oriented software development method supported by a domain specific library of generalized components. This Generalized Support Software (GSS) Domain Engineering Process is currently in use at the NASA GSFC Software Engineering Laboratory (SEL). The key facets of the GSS process are (1) an architecture for rapid deployment of FDD applications, (2) a reuse asset library for FDD classes, and (3) a paradigm shift from developing software to configuring software for mission support. This paper describes the GSS architecture and process, results of fielding the first applications, lessons learned, and future directions

Analysis of Memory Formation during General Anesthesia (Propofol/Remifentanil) for Elective Surgery Using the Process-dissociation Procedure.

Science.gov (United States)

Hadzidiakos, Daniel; Horn, Nadja; Degener, Roland; Buchner, Axel; Rehberg, Benno

2009-08-01

There have been reports of memory formation during general anesthesia. The process-dissociation procedure has been used to determine if these are controlled (explicit/conscious) or automatic (implicit/unconscious) memories. This study used the process-dissociation procedure with the original measurement model and one which corrected for guessing to determine if more accurate results were obtained in this setting. A total of 160 patients scheduled for elective surgery were enrolled. Memory for words presented during propofol and remifentanil general anesthesia was tested postoperatively by using a word-stem completion task in a process-dissociation procedure. To assign possible memory effects to different levels of anesthetic depth, the authors measured depth of anesthesia using the BIS XP monitor (Aspect Medical Systems, Norwood, MA). Word-stem completion performance showed no evidence of memory for intraoperatively presented words. Nevertheless, an evaluation of these data using the original measurement model for process-dissociation data suggested an evidence of controlled (C = 0.05; 95% confidence interval [CI] 0.02-0.08) and automatic (A = 0.11; 95% CI 0.09-0.12) memory processes (P memory processes was obtained. The authors report and discuss parallel findings for published data sets that were generated by using the process-dissociation procedure. Patients had no memories for auditory information presented during propofol/remifentanil anesthesia after midazolam premedication. The use of the process-dissociation procedure with the original measurement model erroneously detected memories, whereas the extended model, corrected for guessing, correctly revealed no memory.

Generalized Least Energy of Separation for Desalination and Other Chemical Separation Processes

Directory of Open Access Journals (Sweden)

Karan H. Mistry

2013-05-01

Full Text Available Increasing global demand for fresh water is driving the development and implementation of a wide variety of seawater desalination technologies driven by different combinations of heat, work, and chemical energy. This paper develops a consistent basis for comparing the energy consumption of such technologies using Second Law efficiency. The Second Law efficiency for a chemical separation process is defined in terms of the useful exergy output, which is the minimum least work of separation required to extract a unit of product from a feed stream of a given composition. For a desalination process, this is the minimum least work of separation for producing one kilogram of product water from feed of a given salinity. While definitions in terms of work and heat input have been proposed before, this work generalizes the Second Law efficiency to allow for systems that operate on a combination of energy inputs, including fuel. The generalized equation is then evaluated through a parametric study considering work input, heat inputs at various temperatures, and various chemical fuel inputs. Further, since most modern, large-scale desalination plants operate in cogeneration schemes, a methodology for correctly evaluating Second Law efficiency for the desalination plant based on primary energy inputs is demonstrated. It is shown that, from a strictly energetic point of view and based on currently available technology, cogeneration using electricity to power a reverse osmosis system is energetically superior to thermal systems such as multiple effect distillation and multistage flash distillation, despite the very low grade heat input normally applied in those systems.

Teaching Improvisation through Processes. Applications in Music Education and Implications for General Education

Directory of Open Access Journals (Sweden)

Michele Biasutti

2017-06-01

Full Text Available Improvisation is an articulated multidimensional activity based on an extemporaneous creative performance. Practicing improvisation, participants expand sophisticated skills such as sensory and perceptual encoding, memory storage and recall, motor control, and performance monitoring. Improvisation abilities have been developed following several methodologies mainly with a product-oriented perspective. A model framed under the socio-cultural theory of learning for designing didactic activities on processes instead of outcomes is presented in the current paper. The challenge is to overcome the mere instructional dimension of some practices of teaching improvisation by designing activities that stimulate self-regulated learning strategies in the students. In the article the present thesis is declined in three ways, concerning the following three possible areas of application: (1 high-level musical learning, (2 musical pedagogy with children, (3 general pedagogy. The applications in the music field focusing mainly on an expert's use of improvisation are discussed. The last section considers how these ideas should transcend music studies, presenting the benefits and the implications of improvisation activities for general learning. Moreover, the application of music education to the following cognitive processes are discussed: anticipation, use of repertoire, emotive communication, feedback and flow. These characteristics could be used to outline a pedagogical method for teaching music improvisation based on the development of reflection, reasoning, and meta-cognition.

Teaching Improvisation through Processes. Applications in Music Education and Implications for General Education.

Science.gov (United States)

Biasutti, Michele

2017-01-01

Improvisation is an articulated multidimensional activity based on an extemporaneous creative performance. Practicing improvisation, participants expand sophisticated skills such as sensory and perceptual encoding, memory storage and recall, motor control, and performance monitoring. Improvisation abilities have been developed following several methodologies mainly with a product-oriented perspective. A model framed under the socio-cultural theory of learning for designing didactic activities on processes instead of outcomes is presented in the current paper. The challenge is to overcome the mere instructional dimension of some practices of teaching improvisation by designing activities that stimulate self-regulated learning strategies in the students. In the article the present thesis is declined in three ways, concerning the following three possible areas of application: (1) high-level musical learning, (2) musical pedagogy with children, (3) general pedagogy. The applications in the music field focusing mainly on an expert's use of improvisation are discussed. The last section considers how these ideas should transcend music studies, presenting the benefits and the implications of improvisation activities for general learning. Moreover, the application of music education to the following cognitive processes are discussed: anticipation, use of repertoire, emotive communication, feedback and flow. These characteristics could be used to outline a pedagogical method for teaching music improvisation based on the development of reflection, reasoning, and meta-cognition.

Degradation data analysis based on a generalized Wiener process subject to measurement error

Science.gov (United States)

Li, Junxing; Wang, Zhihua; Zhang, Yongbo; Fu, Huimin; Liu, Chengrui; Krishnaswamy, Sridhar

2017-09-01

Wiener processes have received considerable attention in degradation modeling over the last two decades. In this paper, we propose a generalized Wiener process degradation model that takes unit-to-unit variation, time-correlated structure and measurement error into considerations simultaneously. The constructed methodology subsumes a series of models studied in the literature as limiting cases. A simple method is given to determine the transformed time scale forms of the Wiener process degradation model. Then model parameters can be estimated based on a maximum likelihood estimation (MLE) method. The cumulative distribution function (CDF) and the probability distribution function (PDF) of the Wiener process with measurement errors are given based on the concept of the first hitting time (FHT). The percentiles of performance degradation (PD) and failure time distribution (FTD) are also obtained. Finally, a comprehensive simulation study is accomplished to demonstrate the necessity of incorporating measurement errors in the degradation model and the efficiency of the proposed model. Two illustrative real applications involving the degradation of carbon-film resistors and the wear of sliding metal are given. The comparative results show that the constructed approach can derive a reasonable result and an enhanced inference precision.

Differing influence on delays in the case-finding process for tuberculosis between general physicians and specialists in Mongolia.

Science.gov (United States)

Enkhbat, S; Toyota, M; Yasuda, N; Ohara, H

1997-06-01

The objective of this study is to compare the influence on delays in the tuberculosis case-finding process according to the types of medical facilities initially visited. The subjects include 107 patients 16 years and older who were diagnosed with bacteriologically confirmed pulmonary tuberculosis at nine tuberculosis specialized facilities in Ulaanbaatar, Mongolia from May 1995 to March 1996. Patients were interviewed about their demographic and socioeconomic factors and their medical records were reviewed for measuring delays. Fifty-five patients initially consulted general physicians and the remaining 52 patients initially visited other types of facilities including tuberculosis specialized facilities. Patients who initially consulted general physicians had shorter patient's delays and longer doctor's delays than those who had visited other facilities first. Since the reduction of patient's delay outweighs the extension of doctor's delay among patients who initially consulted general physicians, their total delay was shorter than that of patients who visited other facilities first. The beneficial influence of consulting general physicians first on the total delay was observed after adjusting for patient's age, sex, residence area, family income and family history of tuberculosis. This finding indicates that general physicians play an important role in improving the passive case-finding process in Mongolia.

Forbidden Raman scattering processes. I. General considerations and E1--M1 scattering

International Nuclear Information System (INIS)

Harney, R.C.

1979-01-01

The generalized theory of forbidden Raman scattering processes is developed in terms of the multipole expansion of the electromagnetic interaction Hamiltonian. Using the general expressions, the theory of electric dipole--magnetic dipole (E1--M1) Raman scattering is derived in detail. The 1 S 0 → 3 P 1 E1--M1 Raman scattering cross section in atomic magnesium is calculated for two applicable laser wavelengths using published f-value data. Since resonantly enhanced cross sections larger than 10 -29 cm 2 /sr are predicted it should be possible to experimentally observe this scattering phenomenon. In addition, by measuring the frequency dependence of the cross section near resonance, it may be possible to directly determine the relative magnitudes of the Axp and AxA contributions to the scattering cross section. Finally, possible applications of the effect in atomic and molecular physics are discussed

Kolmogorov's refined similarity hypotheses for turbulence and general stochastic processes

International Nuclear Information System (INIS)

Stolovitzky, G.; Sreenivasan, K.R.

1994-01-01

Kolmogorov's refined similarity hypotheses are shown to hold true for a variety of stochastic processes besides high-Reynolds-number turbulent flows, for which they were originally proposed. In particular, just as hypothesized for turbulence, there exists a variable V whose probability density function attains a universal form. Analytical expressions for the probability density function of V are obtained for Brownian motion as well as for the general case of fractional Brownian motion---the latter under some mild assumptions justified a posteriori. The properties of V for the case of antipersistent fractional Brownian motion with the Hurst exponent of 1/3 are similar in many details to those of high-Reynolds-number turbulence in atmospheric boundary layers a few meters above the ground. The one conspicuous difference between turbulence and the antipersistent fractional Brownian motion is that the latter does not possess the required skewness. Broad implications of these results are discussed

Entanglement of higher-derivative oscillators in holographic systems

Energy Technology Data Exchange (ETDEWEB)

Dimov, Hristo, E-mail: h_dimov@phys.uni-sofia.bg [Department of Physics, Sofia University, 5 J. Bourchier Blvd., 1164 Sofia (Bulgaria); Mladenov, Stefan, E-mail: smladenov@phys.uni-sofia.bg [Department of Physics, Sofia University, 5 J. Bourchier Blvd., 1164 Sofia (Bulgaria); Rashkov, Radoslav C., E-mail: rash@phys.uni-sofia.bg [Department of Physics, Sofia University, 5 J. Bourchier Blvd., 1164 Sofia (Bulgaria); Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstr. 8–10, 1040 Vienna (Austria); Vetsov, Tsvetan, E-mail: vetsov@phys.uni-sofia.bg [Department of Physics, Sofia University, 5 J. Bourchier Blvd., 1164 Sofia (Bulgaria)

2017-05-15

We study the quantum entanglement of coupled Pais–Uhlenbeck oscillators using the formalism of thermo-field dynamics. The entanglement entropy is computed for the specific cases of two and a ring of N coupled Pais–Uhlenbeck oscillators of fourth order. It is shown that the entanglement entropy depends on the temperatures, frequencies and coupling parameters of the different degrees of freedom corresponding to harmonic oscillators. We also make remarks on the appearance of instabilities of higher-derivative oscillators in the context of AdS/CFT correspondence. Finally, we advert to the information geometry theory by calculating the Fisher information metric for the considered system of coupled oscillators.

Some aspects of nuclear dynamics

International Nuclear Information System (INIS)

Gregoire, C.

1987-01-01

First the BBGKY hierarchy of equations is presented; the method developed here lies on a reduction procedure of a many body density distribution function. From the equations, Hartree and Hartree-Fock approximations are deduced, and time dependent Hartree-Fock equation. Then two derivations of a nuclear reaction kinetic equation are presented: the Woldmann-Snider equation and the Botermans-Malfliet equation. The Wigner transformation is used and the Landau-Vlasov equation is studied. (Or Vlasov-Uehling-Uhlenbeck or Boltzmann-Uehling-Uhlenbeck equation). Keypoints of approximate solutions are mentioned. Simulation calculations of phenomenological collisions are shown. Then dynamics of heavy ion reactions is studied from results presented

Oscillators from nonlinear realizations

Science.gov (United States)

Kozyrev, N.; Krivonos, S.

2018-02-01

We construct the systems of the harmonic and Pais-Uhlenbeck oscillators, which are invariant with respect to arbitrary noncompact Lie algebras. The equations of motion of these systems can be obtained with the help of the formalism of nonlinear realizations. We prove that it is always possible to choose time and the fields within this formalism in such a way that the equations of motion become linear and, therefore, reduce to ones of ordinary harmonic and Pais-Uhlenbeck oscillators. The first-order actions, that produce these equations, can also be provided. As particular examples of this construction, we discuss the so(2, 3) and G 2(2) algebras.

The amblyopic deficit for 2nd order processing: Generality and laterality.

Science.gov (United States)

Gao, Yi; Reynaud, Alexandre; Tang, Yong; Feng, Lixia; Zhou, Yifeng; Hess, Robert F

2015-09-01

A number of previous reports have suggested that the processing of second-order stimuli by the amblyopic eye (AE) is defective and that the fellow non-amblyopic eye (NAE) also exhibits an anomaly. Second-order stimuli involve extra-striate as well as striate processing and provide a means of exploring the extent of the cortical anomaly in amblyopia using psychophysics. We use a range of different second-order stimuli to investigate how general the deficit is for detecting second-order stimuli in adult amblyopes. We compare these results to our previously published adult normative database using the same stimuli and approach to determine the extent to which the detection of these stimuli is defective for both amblyopic and non-amblyopic eye stimulation. The results suggest that the second-order deficit affects a wide range of second-order stimuli, and by implication a large area of extra-striate cortex, both dorsally and ventrally. The NAE is affected only in motion-defined form judgments, suggesting a difference in the degree to which ocular dominance is disrupted in dorsal and ventral extra-striate regions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Memory effects in relativistic heavy ion collisions

International Nuclear Information System (INIS)

Greiner, C.; Wagner, K.; Reinhard, P.

1994-01-01

We consider equilibration in relativistic nuclear dynamics starting from a nonequilibrium Green's-functions approach. The widely used Boltzmann-Uehling-Uhlenbeck equation is obtained only as the Markovian limit (i.e., negligible memory time). The actual memory time in energetic nuclear collisions turns out to be ∼2--3 fm/c, which interferes substantially with the time scale of the relaxation process. The memory kernels of the collision process will be presented. Because of their more involved structure, depending sensitively on the kinematical regime, both less and more stopping power is observed in the reaction compared to the Markovian description

General Process for Business Idea Generation

OpenAIRE

Halinen, Anu

2017-01-01

This thesis presents a process for generating ideas with the intent to propagate new business within a micro-company. Utilizing this newly proposed process, generation of new ideas will be initiated allowing for subsequent business plans to be implemented to grow the existing customer base. Cloudberrywind is a family-owned and family-operated micro company in the Finnish region that offers information technology consulting services and support for project management to improve company efficie...

How Does Processing Affect Storage in Working Memory Tasks? Evidence for Both Domain-General and Domain-Specific Effects

Science.gov (United States)

Jarrold, Christopher; Tam, Helen; Baddeley, Alan D.; Harvey, Caroline E.

2011-01-01

Two studies that examine whether the forgetting caused by the processing demands of working memory tasks is domain-general or domain-specific are presented. In each, separate groups of adult participants were asked to carry out either verbal or nonverbal operations on exactly the same processing materials while maintaining verbal storage items.…

Onset of superfluidity in hot asymmetric nuclear matter

International Nuclear Information System (INIS)

Alm, T.; Roepke, G.; Friman, B.L.

1991-05-01

The onset of superfluidity in hot asymmetric nuclear matter is studied within a generalized Beth-Uhlenbeck approach. The finite tempeature t-matrix is of the Bethe-Goldstone type and contains hole-hole propagation not considered in the Brueckner G-matrix approach. It is shown that the phase contour for the onset of superfluidity in this approach is identical to that obtained within Gorkov's approach to BCS theory. Results for the realistic Paris potential imply that the critical temperature in the neutron-proton triplet channel is on the order of 6-8 MeV and thus much larger than that for singlet pairing. (orig.)

17 CFR 249.510 - Form 10-M, consent to service of process by a nonresident general partner of a broker-dealer firm.

Science.gov (United States)

2010-04-01

..., consent to service of process by a nonresident general partner of a broker-dealer firm. This form shall be... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Form 10-M, consent to service of process by a nonresident general partner of a broker-dealer firm. 249.510 Section 249.510...

General purpose graphics-processing-unit implementation of cosmological domain wall network evolution.

Science.gov (United States)

Correia, J R C C C; Martins, C J A P

2017-10-01

Topological defects unavoidably form at symmetry breaking phase transitions in the early universe. To probe the parameter space of theoretical models and set tighter experimental constraints (exploiting the recent advances in astrophysical observations), one requires more and more demanding simulations, and therefore more hardware resources and computation time. Improving the speed and efficiency of existing codes is essential. Here we present a general purpose graphics-processing-unit implementation of the canonical Press-Ryden-Spergel algorithm for the evolution of cosmological domain wall networks. This is ported to the Open Computing Language standard, and as a consequence significant speedups are achieved both in two-dimensional (2D) and 3D simulations.

General purpose graphics-processing-unit implementation of cosmological domain wall network evolution

Science.gov (United States)

Correia, J. R. C. C. C.; Martins, C. J. A. P.

2017-10-01

Topological defects unavoidably form at symmetry breaking phase transitions in the early universe. To probe the parameter space of theoretical models and set tighter experimental constraints (exploiting the recent advances in astrophysical observations), one requires more and more demanding simulations, and therefore more hardware resources and computation time. Improving the speed and efficiency of existing codes is essential. Here we present a general purpose graphics-processing-unit implementation of the canonical Press-Ryden-Spergel algorithm for the evolution of cosmological domain wall networks. This is ported to the Open Computing Language standard, and as a consequence significant speedups are achieved both in two-dimensional (2D) and 3D simulations.

Information processing during general anesthesia: Evidence for unconscious memory

NARCIS (Netherlands)

A.E. Bonebakker (Annette); B. Bonke (Benno); J. Klein (Jan); G. Wolters (G.); Th. Stijnen (Theo); J. Passchier (Jan); P.M. Merikle (P.)

1996-01-01

textabstractMemory for words presented during general anesthesia was studied in two experiments. In Experiment 1, surgical patients (n=80) undergoing elective procedures under general anesthesia were presented shortly before and during surgery with words via headphones. At the earliest convenient

Cognitive load and emotional processing in Generalized Anxiety Disorder: Electrocortical evidence for increased distractibility

OpenAIRE

MacNamara, Annmarie; Proudfit, Greg Hajcak

2014-01-01

Generalized Anxiety Disorder (GAD) may be characterized by emotion regulation deficits attributable to an imbalance between top-down (i.e., goal-driven) and bottom-up (i.e., stimulus-driven) attention. In prior work, these attentional processes were examined by presenting unpleasant and neutral pictures within a working memory paradigm. The late positive potential (LPP) measured attention toward task-irrelevant pictures. Results from this prior work showed that working memory load reduced the...

Book Reviews

Directory of Open Access Journals (Sweden)

S. Kooijman

1960-07-01

Full Text Available - J.L. Swellengrebel, Jane Belo, Trance in Bali. Columbia University Press, New York 1960. XIII en 284 blz. tekst, 32 blz. foto’s. - P.E. de Josselin de Jong, J.M. Gullick, Indigenous Political Systems of Western Malaya. L.S.E. Monographs on Social Anthropology, no. 17. University of London, The Athlone Press, London 1958. 145 pp. - P.E. de Josselin de Jong, Judith Djamour, Malay kinship and marriage in Singapore. L.S.E. Monographs on Social Anthropology, No. 21. University of London, The Athlone Press, London 1959. 147 pp. - F.D.K. Bosch, A.J. Bernert Kempers, Ancient Indonesian Art. C.P.J. van der Peet, Amsterdam, 1959. 124 blz., 353 pl. - E.M. Uhlenbeck, M.E.J.G. Verstraelen, De bijwoordelijke bepalingen van het werkwoord in enkele Indonesische talen, diss. Utrecht 1955. - E.M. Uhlenbeck, A. Capell, A linguistic survey of the South-Western Pacific. South Pacific Commission Technical Paper no. 70, Noumea, New Caledonia, 1957. IX + 210 pp. with 17 maps. - E.M. Uhlenbeck, C. Maxwell Churchward, Tongan Grammar 1953, Tongan Dictionary 1959, Oxford University Press. - S. Kooijman, Tibor Bodrogi, Oceanian Art. With 160 photographs and 10 colour plates of objects in the custody of the Ethnographical Museum of Budapest. Budapest, 1959. - E.M. Uhlenbeck, H.R. Klieneberger, Bibliography of Oceanic Linguistics. London Oriental Bibliographies Vol. I, 1957. - W.F. Wertheim, Friedrich W. Funke, Dämmerung über Indonesien. Streifzüge durch Sumatra, Java, Bali und Celebes. Carl Schünemann Verlag, Bremen, 1959; 250 pp., 40 blz. foto’s. - G.H.R. von Koenigswald, W.E. le Gros Clark, The antecedents of man. Edinburgh University Publications, Science and Mathematics Texts 2, 1959, pp. 1-374, 152 textfiguren.

Generalization of fear inhibition by disrupting hippocampal protein synthesis-dependent reconsolidation process.

Science.gov (United States)

Yang, Chih-Hao; Huang, Chiung-Chun; Hsu, Kuei-Sen

2011-09-01

Repetitive replay of fear memories may precipitate the occurrence of post-traumatic stress disorder and other anxiety disorders. Hence, the suppression of fear memory retrieval may help prevent and treat these disorders. The formation of fear memories is often linked to multiple environmental cues and these interconnected cues may act as reminders for the recall of traumatic experiences. However, as a convenience, a simple paradigm of one cue pairing with the aversive stimulus is usually used in studies of fear conditioning in animals. Here, we built a more complex fear conditioning model by presenting several environmental stimuli during fear conditioning and characterize the effectiveness of extinction training and the disruption of reconsolidation process on the expression of learned fear responses. We demonstrate that extinction training with a single-paired cue resulted in cue-specific attenuation of fear responses but responses to other cures were unchanged. The cue-specific nature of the extinction persisted despite training sessions combined with D-cycloserine treatment reveals a significant weakness in extinction-based treatment. In contrast, the inhibition of the dorsal hippocampus (DH) but not the basolateral amygdala (BLA)-dependent memory reconsolidation process using either protein synthesis inhibitors or genetic disruption of cAMP-response-element-binding protein-mediated transcription comprehensively disrupted the learned connections between fear responses and all paired environmental cues. These findings emphasize the distinct role of the DH and the BLA in the reconsolidation process of fear memories and further indicate that the disruption of memory reconsolidation process in the DH may result in generalization of fear inhibition.

The utility of an online diagnostic decision support system (Isabel) in general practice: a process evaluation.

Science.gov (United States)

Henderson, Emily J; Rubin, Greg P

2013-05-01

To evaluate the utility of Isabel, an online diagnostic decision support system developed by Isabel Healthcare primarily for secondary medical care, in the general practice setting. Focus groups were conducted with clinicians to understand why and how they used the system. A modified online post-use survey asked practitioners about its impact on their decision-making. Normalization process theory (NPT) was used as a theoretical framework to determine whether the system could be incorporated into routine clinical practice. The system was introduced by NHS County Durham and Darlington in the UK in selected general practices as a three-month pilot. General practitioners and nurse practitioners who had access to Isabel as part of the Primary Care Trust's pilot. General practitioners' views, experiences and usage of the system. Seven general practices agreed to pilot Isabel. Two practices did not subsequently use it. The remaining five practices conducted searches on 16 patients. Post-use surveys (n = 10) indicated that Isabel had little impact on diagnostic decision-making. Focus group participants stated that, although the diagnoses produced by Isabel in general did not have an impact on their decision-making, they would find the tool useful if it were better tailored to the primary care setting. Our analysis concluded that normalization was not likely to occur in its current form. Isabel was of limited utility in this short pilot study and may need further modification for use in general practice.

A generalized multi-dimensional mathematical model for charging and discharging processes in a supercapacitor

Energy Technology Data Exchange (ETDEWEB)

Allu, Srikanth [ORNL; Velamur Asokan, Badri [Exxon Mobil Research and Engineering; Shelton, William A [Louisiana State University; Philip, Bobby [ORNL; Pannala, Sreekanth [ORNL

2014-01-01

A generalized three dimensional computational model based on unied formulation of electrode- electrolyte-electrode system of a electric double layer supercapacitor has been developed. The model accounts for charge transport across the solid-liquid system. This formulation based on volume averaging process is a widely used concept for the multiphase ow equations ([28] [36]) and is analogous to porous media theory typically employed for electrochemical systems [22] [39] [12]. This formulation is extended to the electrochemical equations for a supercapacitor in a consistent fashion, which allows for a single-domain approach with no need for explicit interfacial boundary conditions as previously employed ([38]). In this model it is easy to introduce the spatio-temporal variations, anisotropies of physical properties and it is also conducive for introducing any upscaled parameters from lower length{scale simulations and experiments. Due to the irregular geometric congurations including porous electrode, the charge transport and subsequent performance characteristics of the super-capacitor can be easily captured in higher dimensions. A generalized model of this nature also provides insight into the applicability of 1D models ([38]) and where multidimensional eects need to be considered. In addition, simple sensitivity analysis on key input parameters is performed in order to ascertain the dependence of the charge and discharge processes on these parameters. Finally, we demonstarted how this new formulation can be applied to non-planar supercapacitors

Factors Affecting the Integration of Information Literacy in the Teaching and Learning Processes of General Education Courses

Directory of Open Access Journals (Sweden)

Therdsak Maitaouthong

2011-11-01

Full Text Available This article presents the factors affecting the integration of information literacy in the teaching and learning processes of general education courses at an undergraduate level, where information literacy is used as a tool in the student-centered teaching approach. The research was divided into two phases: (1 The study of factors affecting at a policy level – a qualitative research method conducted through an in-depth interview of the vice president for academic affairs and the Director of the General Education Management Center, and (2 The survey of factors affecting in the teaching and learning processes, which is concluded through the questioning of lecturers of general education courses, and librarians. The qualitative data was analyzed on content, and the quantitative data was analyzed through the use of descriptive statistics, weight of score prioritization and percentage. Two major categories were found to have an impact on integrating information literacy in the teaching and learning of general education courses at an undergraduate level. (1 Six factors at a policy level, namely, institutional policy, administrative structure and system, administrators’ roles, resources and infrastructures, learning resources and supporting programs, and teacher evaluation and development. (2 There are eleven instructional factors: roles of lecturers, roles of librarians, roles of learners, knowledge and understanding of information literacy of lecturers and librarians, cooperation between librarians and lecturers, learning outcomes, teaching plans, teaching methods, teaching activities, teaching aids, and student assessment and evaluation.

General principles of the nuclear criticality safety for handling, processing and transportation fissile materials in the USSR

International Nuclear Information System (INIS)

Vnukov, V.S.; Rjazanov, B.G.; Sviridov, V.I.; Frolov, V.V.; Zubkov, Y.N.

1991-01-01

The paper describes the general principles of nuclear criticality safety for handling, processing, transportation and fissile materials storing. Measures to limit the consequences of critical accidents are discussed for the fuel processing plants and fissile materials storage. The system of scientific and technical measures on nuclear criticality safety as well as the system of control and state supervision based on the rules, limits and requirements are described. The criticality safety aspects for various stages of handling nuclear materials are considered. The paper gives descriptions of the methods and approaches for critical risk assessments for the processing facilities, plants and storages. (Author)

Beyond the Floquet theorem: generalized Floquet formalisms and quasienergy methods for atomic and molecular multiphoton processes in intense laser fields

International Nuclear Information System (INIS)

Chu, S.-I.; Telnov, D.A.

2004-01-01

The advancement of high-power and short-pulse laser technology in the past two decades has generated considerable interest in the study of multiphoton and very high-order nonlinear optical processes of atomic and molecular systems in intense and superintense laser fields, leading to the discovery of a host of novel strong-field phenomena which cannot be understood by the conventional perturbation theory. The Floquet theorem and the time-independent Floquet Hamiltonian method are powerful theoretical framework for the study of bound-bound multiphoton transitions driven by periodically time-dependent fields. However, there are a number of significant strong-field processes cannot be directly treated by the conventional Floquet methods. In this review article, we discuss several recent developments of generalized Floquet theorems, formalisms, and quasienergy methods, beyond the conventional Floquet theorem, for accurate nonperturbative treatment of a broad range of strong-field atomic and molecular processes and phenomena of current interests. Topics covered include (a) artificial intelligence (AI)-most-probable-path approach (MPPA) for effective treatment of ultralarge Floquet matrix problem; (b) non-Hermitian Floquet formalisms and complex quasienergy methods for nonperturbative treatment of bound-free and free-free processes such as multiphoton ionization (MPI) and above-threshold ionization (ATI) of atoms and molecules, multiphoton dissociation (MPD) and above-threshold dissociation (ATD) of molecules, chemical bond softening and hardening, charge-resonance enhanced ionization (CREI) of molecular ions, and multiple high-order harmonic generation (HHG), etc.; (c) many-mode Floquet theorem (MMFT) for exact treatment of multiphoton processes in multi-color laser fields with nonperiodic time-dependent Hamiltonian; (d) Floquet-Liouville supermatrix (FLSM) formalism for exact nonperturbative treatment of time-dependent Liouville equation (allowing for relaxations and

Beyond the Floquet theorem: generalized Floquet formalisms and quasienergy methods for atomic and molecular multiphoton processes in intense laser fields

Science.gov (United States)

Chu, Shih-I.; Telnov, Dmitry A.

2004-02-01

The advancement of high-power and short-pulse laser technology in the past two decades has generated considerable interest in the study of multiphoton and very high-order nonlinear optical processes of atomic and molecular systems in intense and superintense laser fields, leading to the discovery of a host of novel strong-field phenomena which cannot be understood by the conventional perturbation theory. The Floquet theorem and the time-independent Floquet Hamiltonian method are powerful theoretical framework for the study of bound-bound multiphoton transitions driven by periodically time-dependent fields. However, there are a number of significant strong-field processes cannot be directly treated by the conventional Floquet methods. In this review article, we discuss several recent developments of generalized Floquet theorems, formalisms, and quasienergy methods, beyond the conventional Floquet theorem, for accurate nonperturbative treatment of a broad range of strong-field atomic and molecular processes and phenomena of current interests. Topics covered include (a) artificial intelligence (AI)-most-probable-path approach (MPPA) for effective treatment of ultralarge Floquet matrix problem; (b) non-Hermitian Floquet formalisms and complex quasienergy methods for nonperturbative treatment of bound-free and free-free processes such as multiphoton ionization (MPI) and above-threshold ionization (ATI) of atoms and molecules, multiphoton dissociation (MPD) and above-threshold dissociation (ATD) of molecules, chemical bond softening and hardening, charge-resonance enhanced ionization (CREI) of molecular ions, and multiple high-order harmonic generation (HHG), etc.; (c) many-mode Floquet theorem (MMFT) for exact treatment of multiphoton processes in multi-color laser fields with nonperiodic time-dependent Hamiltonian; (d) Floquet-Liouville supermatrix (FLSM) formalism for exact nonperturbative treatment of time-dependent Liouville equation (allowing for relaxations and

Negative ion formation processes: A general review

International Nuclear Information System (INIS)

Alton, G.D.

1990-01-01

The principal negative ion formation processes will be briefly reviewed. Primary emphasis will be placed on the more efficient and universal processes of charge transfer and secondary ion formation through non-thermodynamic surface ionization. 86 refs., 20 figs

Mode coupling theory for nonequilibrium glassy dynamics of thermal self-propelled particles.

Science.gov (United States)

Feng, Mengkai; Hou, Zhonghuai

2017-06-28

We present a mode coupling theory study for the relaxation and glassy dynamics of a system of strongly interacting self-propelled particles, wherein the self-propulsion force is described by Ornstein-Uhlenbeck colored noise and thermal noises are included. Our starting point is an effective Smoluchowski equation governing the distribution function of particle positions, from which we derive a memory function equation for the time dependence of density fluctuations in nonequilibrium steady states. With the basic assumption of the absence of macroscopic currents and standard mode coupling approximation, we can obtain expressions for the irreducible memory function and other relevant dynamic terms, wherein the nonequilibrium character of the active system is manifested through an averaged diffusion coefficient D[combining macron] and a nontrivial structural function S 2 (q) with q being the magnitude of wave vector q. D[combining macron] and S 2 (q) enter the frequency term and the vertex term for the memory function, and thus influence both the short time and the long time dynamics of the system. With these equations obtained, we study the glassy dynamics of this thermal self-propelled particle system by investigating the Debye-Waller factor f q and relaxation time τ α as functions of the persistence time τ p of self-propulsion, the single particle effective temperature T eff as well as the number density ρ. Consequently, we find the critical density ρ c for given τ p shifts to larger values with increasing magnitude of propulsion force or effective temperature, in good accordance with previously reported simulation work. In addition, the theory facilitates us to study the critical effective temperature T for fixed ρ as well as its dependence on τ p . We find that T increases with τ p and in the limit τ p → 0, it approaches the value for a simple passive Brownian system as expected. Our theory also well recovers the results for passive systems and can be

Generalization of the photo process window and its application to OPC test pattern design

Science.gov (United States)

Eisenmann, Hans; Peter, Kai; Strojwas, Andrzej J.

2003-07-01

From the early development phase up to the production phase, test pattern play a key role for microlithography. The requirement for test pattern is to represent the design well and to cover the space of all process conditions, e.g. to investigate the full process window and all other process parameters. This paper shows that the current state-of-the-art test pattern do not address these requirements sufficiently and makes suggestions for a better selection of test pattern. We present a new methodology to analyze an existing layout (e.g. logic library, test pattern or full chip) for critical layout situations which does not need precise process data. We call this method "process space decomposition", because it is aimed at decomposing the process impact to a layout feature into a sum of single independent contributions, the dimensions of the process space. This is a generalization of the classical process window, which examines defocus and exposure dependency of given test pattern, e.g. CD value of dense and isolated lines. In our process space we additionally define the dimensions resist effects, etch effects, mask error and misalignment, which describe the deviation of the printed silicon pattern from its target. We further extend it by the pattern space using a product based layout (library, full chip or synthetic test pattern). The criticality of pattern is defined by their deviation due to aerial image, their sensitivity to the respective dimension or several combinations of these. By exploring the process space for a given design, the method allows to find the most critical patterns independent of specific process parameters. The paper provides examples for different applications of the method: (1) selection of design oriented test pattern for lithography development (2) test pattern reduction in process characterization (3) verification/optimization of printability and performance of post processing procedures (like OPC) (4) creation of a sensitive process

Convexity of Ruin Probability and Optimal Dividend Strategies for a General Lévy Process

Directory of Open Access Journals (Sweden)

Chuancun Yin

2015-01-01

Full Text Available We consider the optimal dividends problem for a company whose cash reserves follow a general Lévy process with certain positive jumps and arbitrary negative jumps. The objective is to find a policy which maximizes the expected discounted dividends until the time of ruin. Under appropriate conditions, we use some recent results in the theory of potential analysis of subordinators to obtain the convexity properties of probability of ruin. We present conditions under which the optimal dividend strategy, among all admissible ones, takes the form of a barrier strategy.

Convexity of Ruin Probability and Optimal Dividend Strategies for a General Lévy Process

Science.gov (United States)

Yuen, Kam Chuen; Shen, Ying

2015-01-01

We consider the optimal dividends problem for a company whose cash reserves follow a general Lévy process with certain positive jumps and arbitrary negative jumps. The objective is to find a policy which maximizes the expected discounted dividends until the time of ruin. Under appropriate conditions, we use some recent results in the theory of potential analysis of subordinators to obtain the convexity properties of probability of ruin. We present conditions under which the optimal dividend strategy, among all admissible ones, takes the form of a barrier strategy. PMID:26351655

Probability of production of internal bremmstrahlung from 99Tc radionuclei

International Nuclear Information System (INIS)

Ei-Konsol, S.; Gaafar, S.A.; Basha, A.M.; Hamed, A.A.

1984-01-01

The internal bremmstrahlung (IB) spectrum accompanying β-decay of 99 Tc (second forbidden β-transition) radionuclei has been measured using a single channel scintillation spectrometer. The measured IB spectrum was analyzed by the variable-width peeling-off method, and then corrected applying the proper corrections. This analyzed and corrected IB spectrum was compared with those calculated according to the original theories of Knipp and Uhlenbeck as well as of Bloch, the Coulomb-corrected theories of Lewis and Ford and of Nilsson, and according to the theory of Fords and Martin. The shape correction factor suggested by Konopinski and Uhlenbeck on the Fermi modification. The experimental results are in good agreement, up to 220 keV, with Nilsson theory after applying the shape correction factor. (author)

SELECTION OF BURST-LIKE TRANSIENTS AND STOCHASTIC VARIABLES USING MULTI-BAND IMAGE DIFFERENCING IN THE PAN-STARRS1 MEDIUM-DEEP SURVEY

Energy Technology Data Exchange (ETDEWEB)

Kumar, S.; Gezari, S.; Heinis, S. [Department of Astronomy, University of Maryland, Stadium Drive, College Park, MD 21224 (United States); Chornock, R.; Berger, E.; Soderberg, A.; Stubbs, C. W.; Kirshner, R. P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Rest, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Huber, M. E.; Narayan, G.; Marion, G. H.; Burgett, W. S. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Foley, R. J. [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Scolnic, D.; Riess, A. G. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Lawrence, A. [Institute for Astronomy, University of Edinburgh Scottish Universities Physics Alliance, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Smartt, S. J.; Smith, K. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Wood-Vasey, W. M. [Pittsburgh Particle Physics, Astrophysics, and Cosmology Center, Department of Physics and Astronomy, University of Pittsburgh, 3941 O' Hara Street, Pittsburgh, PA 15260 (United States); and others

2015-03-20

We present a novel method for the light-curve characterization of Pan-STARRS1 Medium Deep Survey (PS1 MDS) extragalactic sources into stochastic variables (SVs) and burst-like (BL) transients, using multi-band image-differencing time-series data. We select detections in difference images associated with galaxy hosts using a star/galaxy catalog extracted from the deep PS1 MDS stacked images, and adopt a maximum a posteriori formulation to model their difference-flux time-series in four Pan-STARRS1 photometric bands g {sub P1}, r {sub P1}, i {sub P1}, and z {sub P1}. We use three deterministic light-curve models to fit BL transients; a Gaussian, a Gamma distribution, and an analytic supernova (SN) model, and one stochastic light-curve model, the Ornstein-Uhlenbeck process, in order to fit variability that is characteristic of active galactic nuclei (AGNs). We assess the quality of fit of the models band-wise and source-wise, using their estimated leave-out-one cross-validation likelihoods and corrected Akaike information criteria. We then apply a K-means clustering algorithm on these statistics, to determine the source classification in each band. The final source classification is derived as a combination of the individual filter classifications, resulting in two measures of classification quality, from the averages across the photometric filters of (1) the classifications determined from the closest K-means cluster centers, and (2) the square distances from the clustering centers in the K-means clustering spaces. For a verification set of AGNs and SNe, we show that SV and BL occupy distinct regions in the plane constituted by these measures. We use our clustering method to characterize 4361 extragalactic image difference detected sources, in the first 2.5 yr of the PS1 MDS, into 1529 BL, and 2262 SV, with a purity of 95.00% for AGNs, and 90.97% for SN based on our verification sets. We combine our light-curve classifications with their nuclear or off-nuclear host

Evaluation of Aqueous and Powder Processing Techniques for Production of Pu-238-Fueled General Purpose Heat Sources

Energy Technology Data Exchange (ETDEWEB)

2008-06-01

This report evaluates alternative processes that could be used to produce Pu-238 fueled General Purpose Heat Sources (GPHS) for radioisotope thermoelectric generators (RTG). Fabricating GPHSs with the current process has remained essentially unchanged since its development in the 1970s. Meanwhile, 30 years of technological advancements have been made in the fields of chemistry, manufacturing, ceramics, and control systems. At the Department of Energy’s request, alternate manufacturing methods were compared to current methods to determine if alternative fabrication processes could reduce the hazards, especially the production of respirable fines, while producing an equivalent GPHS product. An expert committee performed the evaluation with input from four national laboratories experienced in Pu-238 handling.

Outcrossings of safe regions by generalized hyperbolic processes

DEFF Research Database (Denmark)

Klüppelberg, Claudia; Rasmussen, Morten Grud

2013-01-01

We present a simple Gaussian mixture model in space and time with generalized hyperbolic marginals. Starting with Rice’s celebrated formula for level upcrossings and outcrossings of safe regions we investigate the consequences of the mean-variance mixture model on such quantities. We obtain...

General edition program

International Nuclear Information System (INIS)

Vaturi, Sylvain

1969-01-01

Computerized edition is essential for data processing exploitation. When a more or less complex edition program is required for each task, then the need for a general edition program become obvious. The aim of this study is to create a general edition program. Universal programs are capable to execute numerous and varied tasks. For a more precise processing, the execution of which is frequently required, the use of a specialized program is preferable because, contradictory to the universal program, it goes straight to the point [fr

A Fast General-Purpose Clustering Algorithm Based on FPGAs for High-Throughput Data Processing

CERN Document Server

Annovi, A; The ATLAS collaboration; Castegnaro, A; Gatta, M

2012-01-01

We present a fast general-purpose algorithm for high-throughput clustering of data ”with a two dimensional organization”. The algorithm is designed to be implemented with FPGAs or custom electronics. The key feature is a processing time that scales linearly with the amount of data to be processed. This means that clustering can be performed in pipeline with the readout, without suffering from combinatorial delays due to looping multiple times through all the data. This feature makes this algorithm especially well suited for problems where the data has high density, e.g. in the case of tracking devices working under high-luminosity condition such as those of LHC or Super-LHC. The algorithm is organized in two steps: the first step (core) clusters the data; the second step analyzes each cluster of data to extract the desired information. The current algorithm is developed as a clustering device for modern high-energy physics pixel detectors. However, the algorithm has much broader field of applications. In ...

40 CFR 68.12 - General requirements.

Science.gov (United States)

2010-07-01

...) CHEMICAL ACCIDENT PREVENTION PROVISIONS General § 68.12 General requirements. (a) General requirements. The... the five-year accident history for the process as provided in § 68.42 of this part and submit it in... §§ 68.150 to 68.185. The RMP shall include a registration that reflects all covered processes. (b...

[Systemic inflammation: theoretical and methodological approaches to description of general pathological process model. Part 3. Backgroung for nonsyndromic approach].

Science.gov (United States)

Gusev, E Yu; Chereshnev, V A

2013-01-01

Theoretical and methodological approaches to description of systemic inflammation as general pathological process are discussed. It is shown, that there is a need of integration of wide range of types of researches to develop a model of systemic inflammation.

Geometric correction of radiographic images using general purpose image processing program

International Nuclear Information System (INIS)

Kim, Eun Kyung; Cheong, Ji Seong; Lee, Sang Hoon

1994-01-01

The present study was undertaken to compare geometric corrected image by general-purpose image processing program for the Apple Macintosh II computer (NIH Image, Adobe Photoshop) with standardized image by individualized custom fabricated alignment instrument. Two non-standardized periapical films with XCP film holder only were taken at the lower molar portion of 19 volunteers. Two standardized periapical films with customized XCP film holder with impression material on the bite-block were taken for each person. Geometric correction was performed with Adobe Photoshop and NIH Image program. Specially, arbitrary image rotation function of 'Adobe Photoshop' and subtraction with transparency function of 'NIH Image' were utilized. The standard deviations of grey values of subtracted images were used to measure image similarity. Average standard deviation of grey values of subtracted images if standardized group was slightly lower than that of corrected group. However, the difference was found to be statistically insignificant (p>0.05). It is considered that we can use 'NIH Image' and 'Adobe Photoshop' program for correction of nonstandardized film, taken with XCP film holder at lower molar portion.

Structure of partly quenched molten copper chloride

International Nuclear Information System (INIS)

Pastore, G.; Tosi, M.P.

1995-09-01

The structural modifications induced in a model of molten CuCl by quenching the chlorine component into a microporous disordered matrix are evaluated using the hypernetted-chain closure in Ornstein-Zernike relations for the pair distribution functions in random systems. Aside from obvious changes in the behaviour of long-wavelength density fluctuations, the main effect of partial quenching is an enhanced delocalization of the Cu + ions. The model suggests that the ionic mobility in a superionic glass is enhanced relative to the melt at the same temperature and density. Only very minor quantitative differences are found in the structural functions when the replica Ornstein-Zernike relations derived by Given and Stell for a partly quenched system are simplified to those given earlier by Madden and Glandt. (author). 19 refs, 6 figs

Results of comparative evaluations concerning the psychic process of perceiving and assessing risk-objects by the general public

International Nuclear Information System (INIS)

Peters, H.P.; Renn, O.

1983-01-01

The perception of risk has become a mayor research field, after scientists and politicians recognized that scientific risk studies like the Rasmussen-Report on nuclear energy had no large impact on the public acceptance. With our surveys we aimed to combine two methodological approaches (object perception and attitude theory) and to develop a technique in which the psychic process of perceiving and assessing risk-objects by the general public was followed up and analyzed. Psychological experiments in the field of isolating relevant factors of qualitative risk properties as well as demographic surveys for the measurement of the belief structure were carried out. Our results indicate that in objection to the common conception by natural scientists people in general have a good estimative ability to judge the expected value of different risks. But beyond this estimation of fatalities people also use other criteria (like personal control) to order different objects in respect to their riskiness. The perceived risk is but one factor influencing attitude. A simplified model of the acceptance-building process is carried out showing that acceptance-building is not a purely individual process. Individuals are linked together by their social environment so that every individual decision is influenced by the decision of other people

Inner Bremsstrahlung accompanying the non-unique first forbidden β-decay of 141Ce

International Nuclear Information System (INIS)

Khalil, E.I.

1993-01-01

The inner Bremsstrahlung (I.B.) spectrum accompanying the β-decay of 141 Ce (non-unique first forbidden β-transition) was measured using a single channel scintillation spectrometer. The measured I.B. was analyzed by the variable width peeling-off method. This analyzed and corrected I.B. was compared with those calculated according to the original theories of Knipp and Uhlenbeck as well as of Bloch (KUB), the coulomb corrected theories of Lewis and Ford and of Nilsson, and according to detour-transition calculations of the Ford and Martin theory. Ths shape correction factor suggested by Konopinski and Uhlenbeck on the Fermi β-decay theory was applied to the calculated I.B. based on Nilsson's theory (modified KUB theory). The experimental results are in better agreement with the modified KUB theory than the other theories. (orig.)

Improving the training process of highly skilled bodybuilders in the preparatory period, general preparatory phase

Directory of Open Access Journals (Sweden)

Olexandr Tyhorskyy

2015-10-01

Full Text Available Purpose: to improve the method of training highly skilled bodybuilders. Material and Methods: the study involved eight highly skilled athletes, members of the team of Ukraine on bodybuilding. Results: comparative characteristics of the most commonly used methods of training process in bodybuilding. Developed and substantiated the optimal method of training highly skilled bodybuilders during the general preparatory phase of the preparatory period, which can increase body weight through muscle athletes component. Conclusions: dynamic load factor to raise the intensity of training loads allows orientation help to increase volumes shoulder muscles

Generalizing entanglement

Science.gov (United States)

Jia, Ding

2017-12-01

The expected indefinite causal structure in quantum gravity poses a challenge to the notion of entanglement: If two parties are in an indefinite causal relation of being causally connected and not, can they still be entangled? If so, how does one measure the amount of entanglement? We propose to generalize the notions of entanglement and entanglement measure to address these questions. Importantly, the generalization opens the path to study quantum entanglement of states, channels, networks, and processes with definite or indefinite causal structure in a unified fashion, e.g., we show that the entanglement distillation capacity of a state, the quantum communication capacity of a channel, and the entanglement generation capacity of a network or a process are different manifestations of one and the same entanglement measure.

General relativity and mathematics; Relatividad General y Matematicas

Energy Technology Data Exchange (ETDEWEB)

Mars, M.

2015-07-01

General relativity is more than a theory of gravity, since any physical process occupies space and lasts for a time, forcing to reconcile that physical theory that describes what the dynamic nature of space-time itself. (Author)

Cancer Investigation in General Practice

DEFF Research Database (Denmark)

Jensen, Jacob Reinholdt; Møller, Henrik; Thomsen, Janus Laust

2014-01-01

Initiation of cancer investigations in general practice Background Close to 90% of all cancers are diagnosed because the patient presents symptoms and signs. Of these patients, 85% initiate the diagnostic pathway in general practice. Therefore, the initiation of a diagnostic pathway in general...... practice becomes extremely important. On average, a general practitioner (GP) is involved in 7500 consultations each year, and in the diagnostic process of 8-10 incident cancers. One half of cancer patients consult their GP with either general symptoms, which are not indicative of cancer, or vague and non......-specific symptoms. The other half present with what the GP assess as alarm symptoms. Three months prior to diagnosis, patients who are later diagnosed with cancer have twice as many GP consultations than a comparable reference population. Thus the complex diagnostic process in general practice requires the GP...

Generalized renewal process for repairable systems based on finite Weibull mixture

International Nuclear Information System (INIS)

Veber, B.; Nagode, M.; Fajdiga, M.

2008-01-01

Repairable systems can be brought to one of possible states following a repair. These states are: 'as good as new', 'as bad as old' and 'better than old but worse than new'. The probabilistic models traditionally used to estimate the expected number of failures account for the first two states, but they do not properly apply to the last one, which is more realistic in practice. In this paper, a probabilistic model that is applicable to all of the three after-repair states, called generalized renewal process (GRP), is applied. Simplistically, GRP addresses the repair assumption by introducing the concept of virtual age into the stochastic point processes to enable them to represent the full spectrum of repair assumptions. The shape of measured or design life distributions of systems can vary considerably, and therefore frequently cannot be approximated by simple distribution functions. The scope of the paper is to prove that a finite Weibull mixture, with positive component weights only, can be used as underlying distribution of the time to first failure (TTFF) of the GRP model, on condition that the unknown parameters can be estimated. To support the main idea, three examples are presented. In order to estimate the unknown parameters of the GRP model with m-fold Weibull mixture, the EM algorithm is applied. The GRP model with m mixture components distributions is compared to the standard GRP model based on two-parameter Weibull distribution by calculating the expected number of failures. It can be concluded that the suggested GRP model with Weibull mixture with an arbitrary but finite number of components is suitable for predicting failures based on the past performance of the system

''Sheiva'' : a general purpose multi-parameter data acquisition and processing system at VECC

International Nuclear Information System (INIS)

Viyogi, Y.P.; Ganguly, N.K.

1982-01-01

A general purpose interactive software to be used with the PDP-15/76 on-line computer at VEC Centre for the acquisition and processing of data in nuclear physics experiments is described. The program can accommodate a maximum of thirty two inputs although the present hardware limits the number of inputs to eight. Particular emphasis is given to the problems of flexibility and ease of operation, memory optimisation and techniques dealing with experimenter-computer interaction. Various graphical methods for one- and two-dimensional data presentation are discussed. Specific problems of particle identification using detector telescopes have been dealt with carefully to handle experiments using several detector telescopes and those involving light particle-heavy particle coincidence studies. Steps needed to tailor this program towards utilisation for special experiments are also described. (author)

Recent study, but not retrieval, of knowledge protects against learning errors.

Science.gov (United States)

Mullet, Hillary G; Umanath, Sharda; Marsh, Elizabeth J

2014-11-01

Surprisingly, people incorporate errors into their knowledge bases even when they have the correct knowledge stored in memory (e.g., Fazio, Barber, Rajaram, Ornstein, & Marsh, 2013). We examined whether heightening the accessibility of correct knowledge would protect people from later reproducing misleading information that they encountered in fictional stories. In Experiment 1, participants studied a series of target general knowledge questions and their correct answers either a few minutes (high accessibility of knowledge) or 1 week (low accessibility of knowledge) before exposure to misleading story references. In Experiments 2a and 2b, participants instead retrieved the answers to the target general knowledge questions either a few minutes or 1 week before the rest of the experiment. Reading the relevant knowledge directly before the story-reading phase protected against reproduction of the misleading story answers on a later general knowledge test, but retrieving that same correct information did not. Retrieving stored knowledge from memory might actually enhance the encoding of relevant misinformation.

Distribution functions for fluids in random media

International Nuclear Information System (INIS)

Madden, W.G.; Glandt, E.D.

1988-01-01

A random medium is considered, composed of identifiable interactive sites or obstacles equilibrated at a high temperature and then quenched rapidly to form a rigid structure, statistically homogeneous on all but molecular length scales. The equilibrium statistical mechanics of a fluid contained inside this quenched medium is discussed. Various particle-particle and particle-obstacle correlation functions, which differ form the corresponding functions for a fully equilibrated binary mixture, are defined through an averaging process over the static ensemble of obstacle configurations and applications of topological reduction techniques. The Ornstein-Zernike equations also differ from their equilibrium counterparts

SYSTEM OF COMPUTER MODELING OBJECTS AND PROCESSES AND FEATURES OF ITS USE IN THE EDUCATIONAL PROCESS OF GENERAL SECONDARY EDUCATION

Directory of Open Access Journals (Sweden)

Svitlana G. Lytvynova

2018-04-01

Full Text Available The article analyzes the historical aspect of the formation of computer modeling as one of the perspective directions of educational process development. The notion of “system of computer modeling”, conceptual model of system of computer modeling (SCMod, its components (mathematical, animation, graphic, strategic, functions, principles and purposes of use are grounded. The features of the organization of students work using SCMod, individual and group work, the formation of subject competencies are described; the aspect of students’ motivation to learning is considered. It is established that educational institutions can use SCMod at different levels and stages of training and in different contexts, which consist of interrelated physical, social, cultural and technological aspects. It is determined that the use of SCMod in general secondary school would increase the capacity of teachers to improve the training of students in natural and mathematical subjects and contribute to the individualization of the learning process, in order to meet the pace, educational interests and capabilities of each particular student. It is substantiated that the use of SCMod in the study of natural-mathematical subjects contributes to the formation of subject competencies, develops the skills of analysis and decision-making, increases the level of digital communication, develops vigilance, raises the level of knowledge, increases the duration of attention of students. Further research requires the justification of the process of forming students’ competencies in natural-mathematical subjects and designing cognitive tasks using SCMod.

Estimation in Discretely Observed Diffusions Killed at a Threshold

DEFF Research Database (Denmark)

Bibbona, Enrico; Ditlevsen, Susanne

2013-01-01

are modelled as discretely observed diffusions which are killed when the threshold is reached. Statistical inference is often based on a misspecified likelihood ignoring the presence of the threshold causing severe bias, e.g. the bias incurred in the drift parameters of the Ornstein–Uhlenbeck model...... for biological relevant parameters can be up to 25–100 per cent. We compute or approximate the likelihood function of the killed process. When estimating from a single trajectory, considerable bias may still be present, and the distribution of the estimates can be heavily skewed and with a huge variance...

Generalized Jacobi identities in gauge theories

International Nuclear Information System (INIS)

Chaves, F.M.P.

1990-01-01

A spatial generalized Jacobi identity obeyed by the polarization-dependent factors of the vertices in a q q-bar - Wγ process is studied. The amplitude of a scattering gluon-gluon with five particles is worked out. By reorganizing this amplitude in analogy with an interaction process photon-pion, the non existence of the spatial generalized Jacobi identity, but instead many spatial partial identities that compose themselves, in the case of a four particle process, in one single identity is shown. A process with four particles, three of them scalar fields, but in the one loop approximation is studied. In this case also, the non existence of the spatial generalized Jacobi identity is demonstrated. (author)

Evaluating the implementation of a quality improvement process in General Practice using a realist evaluation framework.

Science.gov (United States)

Moule, Pam; Clompus, Susan; Fieldhouse, Jon; Ellis-Jones, Julie; Barker, Jacqueline

2018-05-25

Underuse of anticoagulants in atrial fibrillation is known to increase the risk of stroke and is an international problem. The National Institute for Health Care and Excellence guidance CG180 seeks to reduce atrial fibrillation related strokes through prescriptions of Non-vitamin K antagonist Oral Anticoagulants. A quality improvement programme was established by the West of England Academic Health Science Network (West of England AHSN) to implement this guidance into General Practice. A realist evaluation identified whether the quality improvement programme worked, determining how and in what circumstances. Six General Practices in 1 region, became the case study sites. Quality improvement team, doctor, and pharmacist meetings within each of the General Practices were recorded at 3 stages: initial planning, review, and final. Additionally, 15 interviews conducted with the practice leads explored experiences of the quality improvement process. Observation and interview data were analysed and compared against the initial programme theory. The quality improvement resources available were used variably, with the training being valued by all. The initial programme theories were refined. In particular, local workload pressures and individual General Practitioner experiences and pre-conceived ideas were acknowledged. Where key motivators were in place, such as prior experience, the programme achieved optimal outcomes and secured a lasting quality improvement legacy. The employment of a quality improvement programme can deliver practice change and improvement legacy outcomes when particular mechanisms are employed and in contexts where there is a commitment to improve service. © 2018 John Wiley & Sons, Ltd.

Proceedings – Mathematical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Uhlenbeck compactification for the moduli space of parabolic stable bundles on an algebraic surface with parabolic structures along a divisor with normal crossing singularities. We prove the non-emptiness of the moduli space of parabolic stable ...

An evolutionary perspective on leaf economics: phylogenetics of leaf mass per area in vascular plants

Czech Academy of Sciences Publication Activity Database

Flores, O.; Garnier, E.; Wright, I. J.; Reich, P. B.; Pirece, S.; Diaz, S.; Pakeman, R. J.; Rusch, G. M.; Bernard-Verdier, M.; Testi, B.; Bakker, J. P.; Bekker, R.M.; Cerabolini, B. E. L.; Ceriani, R. M.; Cornu, G.; Cruz, P.; Delcamp, M.; Doležal, Jiří; Eriksson, O.; Fayolle, A.; Freitas, H.; Golodets, C.; Gourlet-Fleury, S.; Hodgson, J.G.; Brusa, G.; Kleyer, M.; Kunzmann, D.; Lavorel, S.; Papanastasis, V. P.; Pérez-Harguindeguy, N.; Vendramini, F.; Weiher, E.

2014-01-01

Roč. 4, č. 14 (2014), s. 2799-2811 ISSN 2045-7758 Institutional support: RVO:67985939 Keywords : Brownian model * Ornstein– Uhlenbeck model * phenotypic evolution * functional trait Subject RIV: EH - Ecology, Behaviour Impact factor: 2.320, year: 2014

General framework for adsorption processes on dynamic interfaces

International Nuclear Information System (INIS)

Schmuck, Markus; Kalliadasis, Serafim

2016-01-01

We propose a novel and general variational framework modelling particle adsorption mechanisms on evolving immiscible fluid interfaces. A by-product of our thermodynamic approach is that we systematically obtain analytic adsorption isotherms for given equilibrium interfacial geometries. We validate computationally our mathematical methodology by demonstrating the fundamental properties of decreasing interfacial free energies by increasing interfacial particle densities and of decreasing surface pressure with increasing surface area. (paper)

PROCEDIMIENTO GENERAL DE REDISEÑO ORGANIZACIONAL PARA MEJORAR EL ENFOQUE A PROCESOS / GENERAL PROCEDURE OF ORGANIZATIONAL REDESIGN TO IMPROVE THE PROCESS APPROACH

Directory of Open Access Journals (Sweden)

Daniel Alfonso-Robaina

2011-09-01

Full Text Available

Para mejorar el enfoque a procesos en el rediseño de la organización de la empresa, es necesaria la adecuación de 6 fases. En la propuesta se presentan las actividades de cada fase del Procedimiento de rediseño organizacional para mejorar el enfoque a procesos, así como sus entradas y salidas. El procedimiento propuesto en esta investigación es el resultado de la fusión de varios de los estudiados, teniendo como base el procedimiento de Rummler y Brache (1995 [1]. En la investigación fue útil la utilización de técnicas, entre las que se destacan: las entrevistas, la tormenta de ideas y la búsqueda bibliográfica; además del empleo de herramientas como: el Mapa de Procesos y el Modelo General de Organización. Con el uso de estas técnicas y herramientas se identificó como asunto crítico de negocio en la empresa Explomat, la insuficiente gestión integrada de los procesos, lo que debilita las posibilidades de la entidad para aprovechar las oportunidades que le brinda el entorno, poniendo en peligro el cumplimiento de su misión. Teniendo en cuenta el análisis del nivel de integración del sistema de dirección, a partir de las matrices de relaciones, se contribuyó a proyectar mejoras, confeccionando el debe “ser”.

Abstract

In order to improve the process approach relative to the organizational redesign, it is necessary the adaptation of 6 phases. In the proposal, the activities of each phase of the Procedure of organizational redesign to improve the process approach, as well as its inputs and outputs, are presented. The proposed procedure in this investigation is the result of the merger of several of those studied, taking as a starting point the procedure of Rummler and Brache (1995 [1]. In this investigation it was useful the use of techniques, such as the interviews, the brainstorm and bibliographical search; besides the employment of tools like the Processes Map and the General Model of

Quiver Varieties and Branching

Directory of Open Access Journals (Sweden)

Hiraku Nakajima

2009-01-01

Full Text Available Braverman and Finkelberg recently proposed the geometric Satake correspondence for the affine Kac-Moody group Gaff [Braverman A., Finkelberg M., arXiv:0711.2083]. They conjecture that intersection cohomology sheaves on the Uhlenbeck compactification of the framed moduli space of Gcpt-instantons on $R^4/Z_r$ correspond to weight spaces of representations of the Langlands dual group $G_{aff}^{vee}$ at level $r$. When $G = SL(l$, the Uhlenbeck compactification is the quiver variety of type $sl(r_{aff}$, and their conjecture follows from the author's earlier result and I. Frenkel's level-rank duality. They further introduce a convolution diagram which conjecturally gives the tensor product multiplicity [Braverman A., Finkelberg M., Private communication, 2008]. In this paper, we develop the theory for the branching in quiver varieties and check this conjecture for $G = SL(l$.

Investigation of the influence of nuclear charge on the internal Bremsstrahlung accompanying the β-decay of 45Ca and 141Ce

International Nuclear Information System (INIS)

Khalil, E.I.; Basha, A.M.

1995-01-01

The internal Bremsstrahlung (IB) spectrum accompanying the allowed β-decay of 141 Ce was measured using NaI (TI) scintillation spectrometer. The corrected IB distribution was compared with the theories for allowed β-transition of Knipp and Uhlenbeck as well as of Bloch (KUB), Lewis and Ford and Nilsson. Further, for 141 Ce isotope the corrected IB distribution was compared with the Ford and Martin theory (for detour β-transition) and modified KUB theory (where the shape correction factor suggested by Konopinski and Uhlenbeck on the Fermi β-decay theory was applied to the calculated IB based on Nilsson theory). This comparison between experiment and theory, and between the measurements of the two isotopes reflects the role played by the nuclear charge and the degree of forbiddenness on the IB spectrum. (author). 26 refs., 5 figs., 1 tab

40 CFR 425.02 - General definitions.

Science.gov (United States)

2010-07-01

... STANDARDS LEATHER TANNING AND FINISHING POINT SOURCE CATEGORY General Provisions § 425.02 General...) “Chrome tan” means the process of converting hide into leather using a form of chromium. (g) “Vegetable tan” means the process of converting hides into leather using chemicals either derived from vegetable...

An Enumeration of Research to Determine the Optimal Design and Use of Army Flight Training Simulators

Science.gov (United States)

1987-10-01

abstract display format (Williams & Flexman, 1949; Flexman, Matheny, & Brown, 1950; Flexman, Townsend, and Ornstein, 1954; Creelman , 1959; Hennessy, Lintern...Resources Laboratory. Creelman , J. A. (1959). Evaluation of approach training procedures. Pensacola, FL: US. Naval School of Aviation Medicine, 162

Students' General Knowledge of the Learning Process: A Mixed Methods Study Illustrating Integrated Data Collection and Data Consolidation

Science.gov (United States)

van Velzen, Joke H.

2018-01-01

There were two purposes for this mixed methods study: to investigate (a) the realistic meaning of awareness and understanding as the underlying constructs of general knowledge of the learning process and (b) a procedure for data consolidation. The participants were 11th-grade high school and first-year university students. Integrated data…

TRIO-EF a general thermal hydraulics computer code applied to the Avlis process

International Nuclear Information System (INIS)

Magnaud, J.P.; Claveau, M.; Coulon, N.; Yala, P.; Guilbaud, D.; Mejane, A.

1993-01-01

TRIO(EF is a general purpose Fluid Mechanics 3D Finite Element Code. The system capabilities cover areas such as steady state or transient, laminar or turbulent, isothermal or temperature dependent fluid flows; it is applicable to the study of coupled thermo-fluid problems involving heat conduction and possibly radiative heat transfer. It has been used to study the thermal behaviour of the AVLIS process separation module. In this process, a linear electron beam impinges the free surface of a uranium ingot, generating a two dimensional curtain emission of vapour from a water-cooled crucible. The energy transferred to the metal causes its partial melting, forming a pool where strong convective motion increases heat transfer towards the crucible. In the upper part of the Separation Module, the internal structures are devoted to two main functions: vapor containment and reflux, irradiation and physical separation. They are subjected to very high temperature levels and heat transfer occurs mainly by radiation. Moreover, special attention has to be paid to electron backscattering. These two major points have been simulated numerically with TRIO-EF and the paper presents and comments the results of such a computation, for each of them. After a brief overview of the computer code, two examples of the TRIO-EF capabilities are given: a crucible thermal hydraulics model, a thermal analysis of the internal structures

[Informed consent process in clinical trials: Insights of researchers, patients and general practitioners].

Science.gov (United States)

Giménez, Nuria; Pedrazas, David; Redondo, Susana; Quintana, Salvador

2016-10-01

Adequate information for patients and respect for their autonomy are mandatory in research. This article examined insights of researchers, patients and general practitioners (GPs) on the informed consent process in clinical trials, and the role of the GP. A cross-sectional study using three questionnaires, informed consent reviews, medical records, and hospital discharge reports. GPs, researchers and patients involved in clinical trials. Included, 504 GPs, 108 researchers, and 71 patients. Consulting the GP was recommended in 50% of the informed consents. Participation in clinical trials was shown in 33% of the medical records and 3% of the hospital discharge reports. GPs scored 3.54 points (on a 1-10 scale) on the assessment of the information received by the principal investigator. The readability of the informed consent sheet was rated 8.03 points by researchers, and the understanding was rated 7.68 points by patients. Patient satisfaction was positively associated with more time for reflection. GPs were not satisfied with the information received on the participation of patients under their in clinical trials. Researchers were satisfied with the information they offered to patients, and were aware of the need to improve the information GPs received. Patients collaborated greatly towards biomedical research, expressed satisfaction with the overall process, and minimised the difficulties associated with participation. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.

Neural Generalized Predictive Control of a non-linear Process

DEFF Research Database (Denmark)

Sørensen, Paul Haase; Nørgård, Peter Magnus; Ravn, Ole

1998-01-01

The use of neural network in non-linear control is made difficult by the fact the stability and robustness is not guaranteed and that the implementation in real time is non-trivial. In this paper we introduce a predictive controller based on a neural network model which has promising stability qu...... detail and discuss the implementation difficulties. The neural generalized predictive controller is tested on a pneumatic servo sys-tem.......The use of neural network in non-linear control is made difficult by the fact the stability and robustness is not guaranteed and that the implementation in real time is non-trivial. In this paper we introduce a predictive controller based on a neural network model which has promising stability...... qualities. The controller is a non-linear version of the well-known generalized predictive controller developed in linear control theory. It involves minimization of a cost function which in the present case has to be done numerically. Therefore, we develop the numerical algorithms necessary in substantial...

Technical clarification to Silbert and Thomas (2013): "decisional separability, model identification, and statistical inference in the general recognition theory framework".

Science.gov (United States)

Thomas, Robin D; Silbert, Noah H

2014-04-01

We offer a minor technical correction to the published proof of part (ii) of the main theorem in Silbert and Thomas (Psychonomic Bulletin & Review, 20, 1-20, 2013) that somewhat limits the scope of the equivalence observed in that work. Specifically, in order for a mean shift integrality with decisional separability to be mimicked by a perceptually separable but nondecisionally separable configuration, one needs to assume stimulus invariance. This holds when all of the covariance matrices in the stimulus configuration are equal to each other. We note that part (i) of the theorem is unaffected by this modification; an empirical finding of perceptual separability and the failure of decisional separability can be mimicked by a perceptually nonseparable, decisionally separable configuration without restricting the covariance matrices to be equal. We also note that stimulus invariance is often assumed in simple designs (e.g., Macmillan & Ornstein in Journal of the Acoustical Society of America, 97, 1261-1285, 1998), due to the implausibility of different perceptual correlations being present within stimuli perched very closely in perceptual space.

General birth-death processes: probabilities, inference, and applications

OpenAIRE

Crawford, Forrest Wrenn

2012-01-01

A birth-death process is a continuous-time Markov chain that counts the number of particles in a system over time. Each particle can give birth to another particle or die, and the rate of births and deaths at any given time depends on how many extant particles there are. Birth-death processes are popular modeling tools in evolution, population biology, genetics, epidemiology, and ecology. Despite the widespread interest in birth-death models, no efficient method exists to evaluate the fini...

Density functional formulation of the random-phase approximation for inhomogeneous fluids: Application to the Gaussian core and Coulomb particles.

Science.gov (United States)

Frydel, Derek; Ma, Manman

2016-06-01

Using the adiabatic connection, we formulate the free energy in terms of the correlation function of a fictitious system, h_{λ}(r,r^{'}), in which interactions λu(r,r^{'}) are gradually switched on as λ changes from 0 to 1. The function h_{λ}(r,r^{'}) is then obtained from the inhomogeneous Ornstein-Zernike equation and the two equations constitute a general liquid-state framework for treating inhomogeneous fluids. The two equations do not yet constitute a closed set. In the present work we use the closure c_{λ}(r,r^{'})≈-λβu(r,r^{'}), known as the random-phase approximation (RPA). We demonstrate that the RPA is identical with the variational Gaussian approximation derived within the field-theoretical framework, originally derived and used for charged particles. We apply our generalized RPA approximation to the Gaussian core model and Coulomb charges.

A new general methodology for incorporating physico-chemical transformations into multi-phase wastewater treatment process models.

Science.gov (United States)

Lizarralde, I; Fernández-Arévalo, T; Brouckaert, C; Vanrolleghem, P; Ikumi, D S; Ekama, G A; Ayesa, E; Grau, P

2015-05-01

This paper introduces a new general methodology for incorporating physico-chemical and chemical transformations into multi-phase wastewater treatment process models in a systematic and rigorous way under a Plant-Wide modelling (PWM) framework. The methodology presented in this paper requires the selection of the relevant biochemical, chemical and physico-chemical transformations taking place and the definition of the mass transport for the co-existing phases. As an example a mathematical model has been constructed to describe a system for biological COD, nitrogen and phosphorus removal, liquid-gas transfer, precipitation processes, and chemical reactions. The capability of the model has been tested by comparing simulated and experimental results for a nutrient removal system with sludge digestion. Finally, a scenario analysis has been undertaken to show the potential of the obtained mathematical model to study phosphorus recovery. Copyright © 2015 Elsevier Ltd. All rights reserved.

Analytical isotachophoresis

NARCIS (Netherlands)

Everaerts, F.M.

1977-01-01

Electrophoretic separation techniques nowadays seem to be linked mainly with protein chemistry and chromatography, as a result of the work of Hardy, Michaelis, Svedberg, Tiselius, Martin, Svensson, Ornstein and Davis, and many more names could be given. As capillary systems for electrophoresis have

Regulation of activity of the yeast TATA-binding protein through intra ...

Indian Academy of Sciences (India)

Unknown

Abbreviations used: BMH, Bismaleimidohexane; TBP, TATA-binding protein; yTBP, yeast TBP. J. Biosci. | Vol. ... Therefore for full-length TBP, intra-molecular interactions can regulate its activity via a similar ..... simulations (Miaskeiwicz and Ornstein 1996). .... box binding protein (TBP): A molecular dynamics computa-.

UN Secretary-General Normative Capability to Influence The Security Council Decision-Making Process

Directory of Open Access Journals (Sweden)

Dmitry Guennadievich Novik

2016-01-01

Full Text Available The present article studies the issue of the interrelation between the senior UN official - the Secretary-General and the main UN body - the Security Council. The nature of the Secretary-General role is ambiguous since the very creation of the UN. On one hand, the Secretary-General leads the Secretariat - the body that carries out technical and subsidiary functions in relation to other UN Main Bodies. This is the way the Secretary-General position was initially viewed by the UN authors. On the other hand, the UN Charter contains certain provisions that, with a certain representation, give the Secretary-General vigorous powers, including political ones. Since the very beginning of the UN operation the Secretary-Generals have tried to define the nature of these auxiliary powers, formalize the practice of their use. Special place among these powers have the provisions given in the Charter article 99. This article give to the Secretary-General the right to directly appeal to the Security Council and draw its attention to the situation that, in his (Secretary-General's opinion may threaten the international peace and security. This right was used by some Secretary-Generals during different crises occurred after the creation of the UN. This article covers consecutively the crisis in Congo, Iran hostage crisis and the situation in Lebanon. These are three situations that forced Secretary-Generals Hammarskjold, Waldheim and de Cuellar to explicitly use their right to appeal to the Security Council. Other cases in UN history involving the Secretary-General appealing to the Security Council while mentioning article 99 cannot be considered as the use of the nature of this article in full sense of its spirit. Such cases were preceded by other appeals to the Council on the same situations by other subjects (notably, the UN member states or other actions that made Secretary-General to merely perform its technical function. The main research problem here is

Evaluating the Generalization Value of Process-based Models in a Deep-in-time Machine Learning framework

Science.gov (United States)

Shen, C.; Fang, K.

2017-12-01

Deep Learning (DL) methods have made revolutionary strides in recent years. A core value proposition of DL is that abstract notions and patterns can be extracted purely from data, without the need for domain expertise. Process-based models (PBM), on the other hand, can be regarded as repositories of human knowledge or hypotheses about how systems function. Here, through computational examples, we argue that there is merit in integrating PBMs with DL due to the imbalance and lack of data in many situations, especially in hydrology. We trained a deep-in-time neural network, the Long Short-Term Memory (LSTM), to learn soil moisture dynamics from Soil Moisture Active Passive (SMAP) Level 3 product. We show that when PBM solutions are integrated into LSTM, the network is able to better generalize across regions. LSTM is able to better utilize PBM solutions than simpler statistical methods. Our results suggest PBMs have generalization value which should be carefully assessed and utilized. We also emphasize that when properly regularized, the deep network is robust and is of superior testing performance compared to simpler methods.

Gravitational lens produces an odd number of images

International Nuclear Information System (INIS)

McKenzie, R.H.

1985-01-01

Rigorous results are given to the effect that a transparent gravitational lens produces an odd number of images. Suppose that p is an event and T the history of a light source in a globally hyperbolic space-time (M,g). Uhlenbeck's Morse theory of null geodesics is used to show under quite general conditions that if there are at most a finite number n of future-directed null geodesics from T to p, then M is contractible to a point. Moreover, n is odd and 1/2 (n-1) of the images of the source seen by an observer at p have the opposite orientation to the source. An analogous result is noted for Riemannian manifolds with positive definite metric

Clinical Process Intelligence

DEFF Research Database (Denmark)

Vilstrup Pedersen, Klaus

2006-01-01

.e. local guidelines. From a knowledge management point of view, this externalization of generalized processes, gives the opportunity to learn from, evaluate and optimize the processes. "Clinical Process Intelligence" (CPI), will denote the goal of getting generalized insight into patient centered health...

Generalized Software Architecture Applied to the Continuous Lunar Water Separation Process and the Lunar Greenhouse Amplifier

Science.gov (United States)

Perusich, Stephen; Moos, Thomas; Muscatello, Anthony

2011-01-01

This innovation provides the user with autonomous on-screen monitoring, embedded computations, and tabulated output for two new processes. The software was originally written for the Continuous Lunar Water Separation Process (CLWSP), but was found to be general enough to be applicable to the Lunar Greenhouse Amplifier (LGA) as well, with minor alterations. The resultant program should have general applicability to many laboratory processes (see figure). The objective for these programs was to create a software application that would provide both autonomous monitoring and data storage, along with manual manipulation. The software also allows operators the ability to input experimental changes and comments in real time without modifying the code itself. Common process elements, such as thermocouples, pressure transducers, and relative humidity sensors, are easily incorporated into the program in various configurations, along with specialized devices such as photodiode sensors. The goal of the CLWSP research project is to design, build, and test a new method to continuously separate, capture, and quantify water from a gas stream. The application is any In-Situ Resource Utilization (ISRU) process that desires to extract or produce water from lunar or planetary regolith. The present work is aimed at circumventing current problems and ultimately producing a system capable of continuous operation at moderate temperatures that can be scaled over a large capacity range depending on the ISRU process. The goal of the LGA research project is to design, build, and test a new type of greenhouse that could be used on the moon or Mars. The LGA uses super greenhouse gases (SGGs) to absorb long-wavelength radiation, thus creating a highly efficient greenhouse at a future lunar or Mars outpost. Silica-based glass, although highly efficient at trapping heat, is heavy, fragile, and not suitable for space greenhouse applications. Plastics are much lighter and resilient, but are not

How does care coordination provided by registered nurses "fit" within the organisational processes and professional relationships in the general practice context?

Science.gov (United States)

Ehrlich, Carolyn; Kendall, Elizabeth; St John, Winsome

2013-01-01

The aim of this study was to develop understanding about how a registered nurse-provided care coordination model can "fit" within organisational processes and professional relationships in general practice. In this project, registered nurses were involved in implementation of registered nurse-provided care coordination, which aimed to improve quality of care and support patients with chronic conditions to maintain their care and manage their lifestyle. Focus group interviews were conducted with nurses using a semi-structured interview protocol. Interpretive analysis of interview data was conducted using Normalization Process Theory to structure data analysis and interpretation. Three core themes emerged: (1) pre-requisites for care coordination, (2) the intervention in context, and (3) achieving outcomes. Pre-requisites were adequate funding mechanisms, engaging organisational power-brokers, leadership roles, and utilising and valuing registered nurses' broad skill base. To ensure registered nurse-provided care coordination processes were sustainable and embedded, mentoring and support as well as allocated time were required. Finally, when registered nurse-provided care coordination was supported, positive client outcomes were achievable, and transformation of professional practice and development of advanced nursing roles was possible. Registered nurse-provided care coordination could "fit" within the context of general practice if it was adequately resourced. However, the heterogeneity of general practice can create an impasse that could be addressed through close attention to shared and agreed understandings. Successful development and implementation of registered nurse roles in care coordination requires attention to educational preparation, support of the individual nurse, and attention to organisational structures, financial implications and team member relationships.

28 CFR 65.40 - General.

Science.gov (United States)

2010-07-01

... Administration DEPARTMENT OF JUSTICE (CONTINUED) EMERGENCY FEDERAL LAW ENFORCEMENT ASSISTANCE Submission and Review of Applications § 65.40 General. This subpart describes the process and criteria for the Attorney General's review and approval or disapproval of state applications. The original application, on Standard...

Phylogeny and biogeography of Maclura (Moraceae) and the origin of an anachronistic fruit.

Science.gov (United States)

Gardner, Elliot M; Sarraf, Paya; Williams, Evelyn W; Zerega, Nyree J C

2017-12-01

Maclura (ca. 12spp., Moraceae) is a widespread genus of trees and woody climbers found on five continents. Maclura pomifera, the Osage orange, is considered a classic example of an anachronistic fruit. Native to the central USA, the grapefruit-sized Osage oranges are unpalatable and have no known extant native dispersers, leading to speculation that the fruits were adapted to extinct megafauna. Our aim was to reconstruct the phylogeny, estimate divergence dates, and infer ancestral ranges of Maclura in order to test the monophyly of subgeneric classifications and to understand evolution and dispersal patterns in this globally distributed group. Employing Bayesian and maximum-likelihood methods, we reconstructed the Maclura phylogeny using two nuclear and five chloroplast loci from all Maclura species and outgroups representing all Moraceae tribes. We reconstructed ancestral ranges and syncarp sizes using a family level dated tree, and used Ornstein-Uhlenbeck models to test for significant changes in syncarp size in the Osage orange lineage. Our analyses support a monophyletic Maclura with a Paleocene crown. Subgeneric sections were monophyletic except for the geographically-disjunct Cardiogyne. There was strong support for current species delineations except in the widespread M. cochinchinensis. South America was reconstructed as the ancestral range for Maclura with subsequent colonization of Africa and the northern hemisphere. The clade containing M. pomifera likely diverged in the Oligocene, closely coinciding with crown divergence dates of the mammoth/mastodon and sloth clades that contain possible extinct dispersers. The best fitting model for syncarp size evolution indicated an increase in both syncarp size and the rate of syncarp size evolution in the Osage orange lineage. We conclude that our findings are consistent with the hypothesis that M. pomifera was adapted to dispersal by extinct megafauna. In addition, we consider dispersal rather than vicariance to

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

International Nuclear Information System (INIS)

Johnson, E.

1977-01-01

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

Second virial coefficient from the scattering operator in quantum mechanics

Energy Technology Data Exchange (ETDEWEB)

Cognola, G; Soldati, R; Zerbini, S [Libera Universita di Trento (Italy). Dept. di Matematica e Fisica

1977-12-17

A new expression is proposed for the second virial coefficient in quantum statistical mechanics in which there is no reference to the interaction potential, but only the S matrix appears. Then it is shown that our expression reproduces the well-known Beth-Uhlenbeck formula.

Combining Generalized Renewal Processes with Non-Extensive Entropy-Based q-Distributions for Reliability Applications

Directory of Open Access Journals (Sweden)

Isis Didier Lins

2018-03-01

Full Text Available The Generalized Renewal Process (GRP is a probabilistic model for repairable systems that can represent the usual states of a system after a repair: as new, as old, or in a condition between new and old. It is often coupled with the Weibull distribution, widely used in the reliability context. In this paper, we develop novel GRP models based on probability distributions that stem from the Tsallis’ non-extensive entropy, namely the q-Exponential and the q-Weibull distributions. The q-Exponential and Weibull distributions can model decreasing, constant or increasing failure intensity functions. However, the power law behavior of the q-Exponential probability density function for specific parameter values is an advantage over the Weibull distribution when adjusting data containing extreme values. The q-Weibull probability distribution, in turn, can also fit data with bathtub-shaped or unimodal failure intensities in addition to the behaviors already mentioned. Therefore, the q-Exponential-GRP is an alternative for the Weibull-GRP model and the q-Weibull-GRP generalizes both. The method of maximum likelihood is used for their parameters’ estimation by means of a particle swarm optimization algorithm, and Monte Carlo simulations are performed for the sake of validation. The proposed models and algorithms are applied to examples involving reliability-related data of complex systems and the obtained results suggest GRP plus q-distributions are promising techniques for the analyses of repairable systems.

Semiclassical and phase space approaches to dynamic and collisional problems of nuclei

International Nuclear Information System (INIS)

Hasse, R.W.; Gregoire, C.; Remaud, B.; Jaenicke, J.; Schuck, P.

1988-09-01

This article summarises recent work on the semiclassical (Thomas-Fermi like) treatment of nuclear correlations and dynamical problems. After a short outline of hte general technique the nucleon-nucleus optical potential in the doorway approximation (2p-1h and 2h-1p intermediate states) is treated. The imaginary part serves to calculate the energy dependent correction to the real part. The level density parameter, occupation numbers, and the mean free path are discussed. The semiclassical treatment of the nuclear response function is given in detail. Applications to inelastic electron scattering in the quasi-elastic peak region are presented. Analogously, inelastic proton scattering is calculated. Because of the surface absorption this reaction excites the surface response. The imaginary part of the single-particle (hole) potential in the evaluation of the response function introduces a 2p-2h spreading. The missing charge in the longitudinal response is reduced but not all experimental puzzles can be explained. The experience gained in the description of phenomena close to equilibrium serves to construct solutions of the Landau-Vlasov (alias Vlasov-Uehling-Uhlenbeck) equation for the description of non-equilibrium processes encountered in heavy ion reactions

VoxelMages: a general-purpose graphical interface for designing geometries and processing DICOM images for PENELOPE.

Science.gov (United States)

Giménez-Alventosa, V; Ballester, F; Vijande, J

2016-12-01

The design and construction of geometries for Monte Carlo calculations is an error-prone, time-consuming, and complex step in simulations describing particle interactions and transport in the field of medical physics. The software VoxelMages has been developed to help the user in this task. It allows to design complex geometries and to process DICOM image files for simulations with the general-purpose Monte Carlo code PENELOPE in an easy and straightforward way. VoxelMages also allows to import DICOM-RT structure contour information as delivered by a treatment planning system. Its main characteristics, usage and performance benchmarking are described in detail. Copyright © 2016 Elsevier Ltd. All rights reserved.

23 CFR 710.301 - General.

Science.gov (United States)

2010-04-01

... 23 Highways 1 2010-04-01 2010-04-01 false General. 710.301 Section 710.301 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RIGHT-OF-WAY AND ENVIRONMENT RIGHT-OF-WAY AND REAL ESTATE Project Development § 710.301 General. The project development process typically follows a...

O(3)-invariant tunneling in general relativity

International Nuclear Information System (INIS)

Berezin, V.A.; Tkachev, I.I.; Kuzmin, V.A.; AN SSSR, Moscow. Inst. Yadernykh Issledovanij)

1987-12-01

We derived a general formula for the action for any O(3)-invariant tunneling processes in false vacuum decay in general relativity. The general classification of the bubble Euclidean trajectories is elaborated and explicit expressions for bounces for some processes like the vacuum creation of a double bubble, in particular in the vicinity of a black hole; the subbarrier creation of the Einstein-Rosen bridge, creation from nothing of two Minkowski worlds connected by a shell etc., are given. (orig.)

Processing of FRG mixed oxide fuel elements at General Atomic under the US/FRG cooperative agreement for spent fuel elements

International Nuclear Information System (INIS)

Holder, N.D.; Strand, J.B.; Schwarz, F.A.; Tischer, H.E.

1980-11-01

The Federal Republic of Germany (FRG) and the United States (US) are cooperating on certain aspects gas-cooled reactor technology under an umbrella agreement. Under the spent fuel treatment section of the agreement, FRG fuel spheres were recently sent for processing in the Department of Energy sponsored cold pilot plant for High-Temperature Gas-Cooled Reactor (HTGR) fuel processing at General Atomic Company in San Diego, California. The FRG fuel spheres were crushed and burned to recover coated fuel particles. These particles were in turn crushed and burned to recover the fuel-bearing kernels for further treatment for uranium recovery. Successful completion of the tests described in this paper demonstrated the applicability of the US HTGR fuel treatment flowsheet to FRG fuel processing. 10 figures

28 CFR 33.60 - General.

Science.gov (United States)

2010-07-01

... 28 Judicial Administration 1 2010-07-01 2010-07-01 false General. 33.60 Section 33.60 Judicial Administration DEPARTMENT OF JUSTICE BUREAU OF JUSTICE ASSISTANCE GRANT PROGRAMS Criminal Justice Block Grants Submission and Review of Applications § 33.60 General. This subpart describes the process and criteria for...

Imprecision and uncertainty in information representation and processing new tools based on intuitionistic fuzzy sets and generalized nets

CERN Document Server

Sotirov, Sotir

2016-01-01

The book offers a comprehensive and timely overview of advanced mathematical tools for both uncertainty analysis and modeling of parallel processes, with a special emphasis on intuitionistic fuzzy sets and generalized nets. The different chapters, written by active researchers in their respective areas, are structured to provide a coherent picture of this interdisciplinary yet still evolving field of science. They describe key tools and give practical insights into and research perspectives on the use of Atanassov's intuitionistic fuzzy sets and logic, and generalized nets for describing and dealing with uncertainty in different areas of science, technology and business, in a single, to date unique book. Here, readers find theoretical chapters, dealing with intuitionistic fuzzy operators, membership functions and algorithms, among other topics, as well as application-oriented chapters, reporting on the implementation of methods and relevant case studies in management science, the IT industry, medicine and/or ...

Giving up the ghost

International Nuclear Information System (INIS)

Bender, Carl M; Mannheim, Philip D

2008-01-01

The Pais-Uhlenbeck model is a quantum theory described by a higher-derivative field equation. It has been believed for many years that this model possesses ghost states (quantum states of negative norm) and therefore that this model is a physically unacceptable quantum theory. The existence of such ghost states was believed to be attributable to the field equation having more than two derivatives. This paper shows that the Pais-Uhlenbeck model does not possess any ghost states at all and that it is a perfectly acceptable quantum theory. The supposed ghost states in this model arise if the Hamiltonian of the model is (incorrectly) treated as being Dirac Hermitian (invariant under combined matrix transposition and complex conjugation). However, the Hamiltonian is not Dirac Hermitian, but rather it is PT symmetric. When it is quantized correctly according to the rules of PT quantum mechanics, the energy spectrum is real and bounded below and all of the quantum states have positive norm

Stochastic Modeling of Wind Derivatives in Energy Markets

Directory of Open Access Journals (Sweden)

Fred Espen Benth

2018-05-01

Full Text Available We model the logarithm of the spot price of electricity with a normal inverse Gaussian (NIG process and the wind speed and wind power production with two Ornstein–Uhlenbeck processes. In order to reproduce the correlation between the spot price and the wind power production, namely between a pure jump process and a continuous path process, respectively, we replace the small jumps of the NIG process by a Brownian term. We then apply our models to two different problems: first, to study from the stochastic point of view the income from a wind power plant, as the expected value of the product between the electricity spot price and the amount of energy produced; then, to construct and price a European put-type quanto option in the wind energy markets that allows the buyer to hedge against low prices and low wind power production in the plant. Calibration of the proposed models and related price formulas is also provided, according to specific datasets.

Optimal Constant-Stress Accelerated Degradation Test Plans Using Nonlinear Generalized Wiener Process

Directory of Open Access Journals (Sweden)

Zhen Chen

2016-01-01

Full Text Available Accelerated degradation test (ADT has been widely used to assess highly reliable products’ lifetime. To conduct an ADT, an appropriate degradation model and test plan should be determined in advance. Although many historical studies have proposed quite a few models, there is still room for improvement. Hence we propose a Nonlinear Generalized Wiener Process (NGWP model with consideration of the effects of stress level, product-to-product variability, and measurement errors for a higher estimation accuracy and a wider range of use. Then under the constraints of sample size, test duration, and test cost, the plans of constant-stress ADT (CSADT with multiple stress levels based on the NGWP are designed by minimizing the asymptotic variance of the reliability estimation of the products under normal operation conditions. An optimization algorithm is developed to determine the optimal stress levels, the number of units allocated to each level, inspection frequency, and measurement times simultaneously. In addition, a comparison based on degradation data of LEDs is made to show better goodness-of-fit of the NGWP than that of other models. Finally, optimal two-level and three-level CSADT plans under various constraints and a detailed sensitivity analysis are demonstrated through examples in this paper.

Improvement of the training process of qualified female athletes engaged in bodybuilding in the general preparatory stage of the preparatory period, taking into account the biological cycle

Directory of Open Access Journals (Sweden)

Viacheslav Mulyk

2017-06-01

Full Text Available Purpose: substantiation of the methodology of the training process of qualified female athletes engaged in bodybuilding in the general preparatory stage of the preparatory period, taking into account the biological cycle. Material & Methods: in the study participated 18 qualified female athletes engaged in bodybuilding, included in the Kharkov region team of bodybuilding. Results: comparative characteristic of the most frequently used methodology of the training process in bodybuilding are shows. An optimal methodology for qualified female athletes engaged in bodybuilding has been developed and justified, depending on the initial form of the athlete at the beginning of the general preparatory stage of the training. The dependence of the change in the body weight of female athletes from the training process is shows. Conclusion: on the basis of the study, the author suggests an optimal training methodology depending on the mesocycle of training in the preparatory period in the general preparatory stage.

21 CFR 880.6890 - General purpose disinfectants.

Science.gov (United States)

2010-04-01

... (CONTINUED) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use... disinfectant is a germicide intended to process noncritical medical devices and equipment surfaces. A general... prior to terminal sterilization or high level disinfection. Noncritical medical devices make only...

Impact of stuttering severity on adolescents' domain-specific and general self-esteem through cognitive and emotional mediating processes.

Science.gov (United States)

Adriaensens, Stefanie; Beyers, Wim; Struyf, Elke

2015-01-01

The theory that self-esteem is substantially constructed based on social interactions implies that having a stutter could have a negative impact on self-esteem. Specifically, self-esteem during adolescence, a period of life characterized by increased self-consciousness, could be at risk. In addition to studying mean differences between stuttering and non-stuttering adolescents, this article concentrates on the influence of stuttering severity on domain-specific and general self-esteem. Subsequently, we investigate if covert processes on negative communication attitudes, experienced stigma, non-disclosure of stuttering, and (mal)adaptive perfectionism mediate the relationship between stuttering severity and self-esteem. Our sample comprised 55 stuttering and 76 non-stuttering adolescents. They were asked to fill in a battery of questionnaires, consisting of: Subjective Screening of Stuttering, Self-Perception Profile for Adolescents, Erickson S-24, Multidimensional Perfectionism Scale, and the Stigmatization and Disclosure in Adolescents Who Stutter Scale. SEM (structural equation modeling) analyses showed that stuttering severity negatively influences adolescents' evaluations of social acceptance, school competence, the competence to experience a close friendship, and global self-esteem. Maladaptive perfectionism and especially negative communication attitudes fully mediate the negative influence of stuttering severity on self-esteem. Group comparison showed that the mediation model applies to both stuttering and non-stuttering adolescents. We acknowledge the impact of having a stutter on those domains of the self in which social interactions and communication matter most. We then accentuate that negative attitudes about communication situations and excessive worries about saying things in ways they perceive as wrong are important processes to consider with regard to the self-esteem of adolescents who stutter. Moreover, we provide evidence that these covert

Diphoton generalized distribution amplitudes

International Nuclear Information System (INIS)

El Beiyad, M.; Pire, B.; Szymanowski, L.; Wallon, S.

2008-01-01

We calculate the leading order diphoton generalized distribution amplitudes by calculating the amplitude of the process γ*γ→γγ in the low energy and high photon virtuality region at the Born order and in the leading logarithmic approximation. As in the case of the anomalous photon structure functions, the γγ generalized distribution amplitudes exhibit a characteristic lnQ 2 behavior and obey inhomogeneous QCD evolution equations.

Management of the General Process of Parenteral Nutrition Using mHealth Technologies: Evaluation and Validation Study.

Science.gov (United States)

Cervera Peris, Mercedes; Alonso Rorís, Víctor Manuel; Santos Gago, Juan Manuel; Álvarez Sabucedo, Luis; Wanden-Berghe, Carmina; Sanz-Valero, Javier

2018-04-03

Any system applied to the control of parenteral nutrition (PN) ought to prove that the process meets the established requirements and include a repository of records to allow evaluation of the information about PN processes at any time. The goal of the research was to evaluate the mobile health (mHealth) app and validate its effectiveness in monitoring the management of the PN process. We studied the evaluation and validation of the general process of PN using an mHealth app. The units of analysis were the PN bags prepared and administered at the Son Espases University Hospital, Palma, Spain, from June 1 to September 6, 2016. For the evaluation of the app, we used the Poststudy System Usability Questionnaire and subsequent analysis with the Cronbach alpha coefficient. Validation was performed by checking the compliance of control for all operations on each of the stages (validation and transcription of the prescription, preparation, conservation, and administration) and by monitoring the operative control points and critical control points. The results obtained from 387 bags were analyzed, with 30 interruptions of administration. The fulfillment of stages was 100%, including noncritical nonconformities in the storage control. The average deviation in the weight of the bags was less than 5%, and the infusion time did not present deviations greater than 1 hour. The developed app successfully passed the evaluation and validation tests and was implemented to perform the monitoring procedures for the overall PN process. A new mobile solution to manage the quality and traceability of sensitive medicines such as blood-derivative drugs and hazardous drugs derived from this project is currently being deployed. ©Mercedes Cervera Peris, Víctor Manuel Alonso Rorís, Juan Manuel Santos Gago, Luis Álvarez Sabucedo, Carmina Wanden-Berghe, Javier Sanz-Valero. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 03.04.2018.

A generalized additive regression model for survival times

DEFF Research Database (Denmark)

Scheike, Thomas H.

2001-01-01

Additive Aalen model; counting process; disability model; illness-death model; generalized additive models; multiple time-scales; non-parametric estimation; survival data; varying-coefficient models......Additive Aalen model; counting process; disability model; illness-death model; generalized additive models; multiple time-scales; non-parametric estimation; survival data; varying-coefficient models...

Dynamical realizations of l-conformal Newton–Hooke group

International Nuclear Information System (INIS)

Galajinsky, Anton; Masterov, Ivan

2013-01-01

The method of nonlinear realizations and the technique previously developed in [A. Galajinsky, I. Masterov, Nucl. Phys. B 866 (2013) 212, (arXiv:1208.1403)] are used to construct a dynamical system without higher derivative terms, which holds invariant under the l-conformal Newton–Hooke group. A configuration space of the model involves coordinates, which parametrize a particle moving in d spatial dimensions and a conformal mode, which gives rise to an effective external field. The dynamical system describes a generalized multi-dimensional oscillator, which undergoes accelerated/decelerated motion in an ellipse in accord with evolution of the conformal mode. Higher derivative formulations are discussed as well. It is demonstrated that the multi-dimensional Pais–Uhlenbeck oscillator enjoys the l=3/2 -conformal Newton–Hooke symmetry for a particular choice of its frequencies

Exposure to rubber fume and rubber process dust in the general rubber goods, tyre manufacturing and retread industries.

Science.gov (United States)

Dost, A A; Redman, D; Cox, G

2000-08-01

This study assesses the current patterns and levels of exposure to rubber fume and rubber process dust in the British rubber industry and compares and contrasts the data obtained from the general rubber goods (GRG), retread tire (RT) and new tire (NT) sectors. A total of 179 rubber companies were visited and data were obtained from 52 general rubber goods, 29 retread tire and 7 new tire manufacturers. The survey was conducted using a questionnaire and included a walk-through inspection of the workplace to assess the extent of use of control measures and the nature of work practices being employed. The most recent (predominantly 1995-97) exposure monitoring data for rubber fume and rubber process dust were obtained from these companies; no additional sampling was conducted for the purpose of this study. In addition to the assessment of exposure data, evaluation of occupational hygiene reports for the quality of information and advice was also carried out.A comparison of the median exposures for processes showed that the order of exposure to rubber fume (E, in mg m(-3)) is: E(moulding) (0.40) approximately E(extrusion) (0.33)>E(milling) (0.18) for GRG; E(press) (0. 32)>E(extrusion) (0.19)>E(autoclave) (0.10) for RT; and E(press) (0. 22) approximately E(all other) (0.22) for NT. The order of exposure to rubber fume between sectors was E(GRG) (0.40)>E(RT) (0.32)>E(NT) (0.22). Median exposures to rubber process dust in the GRG was E(weighing) (4.2)>E(mixing) (1.2) approximately E(milling) (0.8) approximately E(extrusion) (0.8) and no significant difference (P=0. 31) between GRG and NT sectors. The findings compare well with the study carried out in the Netherlands [Kromhout et al. (1994), Annals of Occupational Hygiene 38(1), 3-22], and it is suggested that the factors governing the significant differences noted between the three sectors relate principally to the production and task functions and also to the extent of controls employed. Evaluation of occupational

Nuclear shape evolution starting from superdeformed state. Role of two-body collision and rotation

International Nuclear Information System (INIS)

Liu, Yu-xin; Sakata, Fumihiko

1999-01-01

With the nuclear density distribution being simulated by the Boltzmann Uehling-Uhlenbeck equation and Vlasov equation with several rotational frequencies, the time evolution of the quadrupole moment of nucleus 86 Zr starting with superdeformed shape is studied. The contribution of two-body collisions and the effects of collective rotation to the shape evolution is investigated. The numerical results indicate that the two-body collisions play a role of damping on the evolution from a superdeformed shape to a normal deformed one in a case without rotation. In a case of rotation with lower frequency, the two-body collisions accelerate the evolution process. A new role of the collective rotation to enhance the nuclear fission is proposed. (author)

Generally representative is generally representative: comment on Shuttleworth-Edwards.

Science.gov (United States)

Taylor, Nicola

2016-10-01

The aim of this paper is to provide comment on Shuttleworth-Edwards' criticism of the general population norms created for the South African adaptation of the WAIS-IV. In her criticism, she states that the norms are not applicable for any groups in South Africa, based on the fact that the norms were not stratified according to quality of education. A discussion of some of the key issues that impact on the creation of general population norms in the South African context is provided. Demographic characteristics such as education level, quality of education, urban and rural demarcations, and home language are all considered. While the utility of within-group norms is not denied, the adoption of these without reference to the general population is not advised. To recommend that practitioners simply dispense with the general population norm without evidence that it creates misclassification or does not function effectively for the intended population lacks scientific merit at the current time. The need for clinical studies and further predictive validity research using the South African adaptation of the WAIS-IV is crucial to demonstrate the continued utility of the test in the South African context. Additional reference groups will improve the amount of comparative information available for clinicians to be able to make better informed decisions for diagnosis, but the general population norms will be an important starting point in this process.

Generalized enthalpy model of a high-pressure shift freezing process

KAUST Repository

Smith, N. A. S.; Peppin, S. S. L.; Ramos, A. M.

2012-01-01

High-pressure freezing processes are a novel emerging technology in food processing, offering significant improvements to the quality of frozen foods. To be able to simulate plateau times and thermal history under different conditions, in this work

Dynamical simulation of heavy ion collisions; VUU and QMD method

International Nuclear Information System (INIS)

Niita, Koji

1992-01-01

We review two simulation methods based on the Vlasov-Uehling-Uhlenbeck (VUU) equation and Quantum Molecular Dynamics (QMD), which are the most widely accepted theoretical framework for the description of intermediate-energy heavy-ion reactions. We show some results of the calculations and compare them with the experimental data. (author)

One-loop QCD and Higgs bosons to partons processes using six-dimensional helicity and generalized unitarity

International Nuclear Information System (INIS)

Davies, Scott

2011-01-01

We combine the six-dimensional helicity formalism of Cheung and O'Connell with D-dimensional generalized unitarity to obtain a new formalism for computing one-loop amplitudes in dimensionally regularized QCD. With this procedure, we simultaneously obtain the pieces that are constructible from four-dimensional unitarity cuts and the rational pieces that are missed by them, while retaining a helicity formalism. We illustrate the procedure using four- and five-point one-loop amplitudes in QCD, including examples with external fermions. We also demonstrate the technique's effectiveness in next-to-leading order QCD corrections to Higgs processes by computing the next-to-leading order correction to the Higgs plus three positive-helicity gluons amplitude in the large top-quark mass limit.

Real-time video signal processing by generalized DDA and control memories: three-dimensional rotation and mapping

Science.gov (United States)

Hama, Hiromitsu; Yamashita, Kazumi

1991-11-01

A new method for video signal processing is described in this paper. The purpose is real-time image transformations at low cost, low power, and small size hardware. This is impossible without special hardware. Here generalized digital differential analyzer (DDA) and control memory (CM) play a very important role. Then indentation, which is called jaggy, is caused on the boundary of a background and a foreground accompanied with the processing. Jaggy does not occur inside the transformed image because of adopting linear interpretation. But it does occur inherently on the boundary of the background and the transformed images. It causes deterioration of image quality, and must be avoided. There are two well-know ways to improve image quality, blurring and supersampling. The former does not have much effect, and the latter has the much higher cost of computing. As a means of settling such a trouble, a method is proposed, which searches for positions that may arise jaggy and smooths such points. Computer simulations based on the real data from VTR, one scene of a movie, are presented to demonstrate our proposed scheme using DDA and CMs and to confirm the effectiveness on various transformations.

Perturbed GUE Minor Process and Warren's Process with Drifts

Science.gov (United States)

Ferrari, Patrik L.; Frings, René

2014-01-01

We consider the minor process of (Hermitian) matrix diffusions with constant diagonal drifts. At any given time, this process is determinantal and we provide an explicit expression for its correlation kernel. This is a measure on the Gelfand-Tsetlin pattern that also appears in a generalization of Warren's process (Electron. J. Probab. 12:573-590, 2007), in which Brownian motions have level-dependent drifts. Finally, we show that this process arises in a diffusion scaling limit from an interacting particle system in the anisotropic KPZ class in 2+1 dimensions introduced in Borodin and Ferrari (Commun. Math. Phys., 2008). Our results generalize the known results for the zero drift situation.

Genetic Process Mining: Alignment-based Process Model Mutation

NARCIS (Netherlands)

Eck, van M.L.; Buijs, J.C.A.M.; Dongen, van B.F.; Fournier, F.; Mendling, J.

2015-01-01

The Evolutionary Tree Miner (ETM) is a genetic process discovery algorithm that enables the user to guide the discovery process based on preferences with respect to four process model quality dimensions: replay fitness, precision, generalization and simplicity. Traditionally, the ETM algorithm uses

Generalization of Gibbs Entropy and Thermodynamic Relation

OpenAIRE

Park, Jun Chul

2010-01-01

In this paper, we extend Gibbs's approach of quasi-equilibrium thermodynamic processes, and calculate the microscopic expression of entropy for general non-equilibrium thermodynamic processes. Also, we analyze the formal structure of thermodynamic relation in non-equilibrium thermodynamic processes.

The professional’s orientation in the formative process for the bachelor’s general united students

Directory of Open Access Journals (Sweden)

Darwin Stalin Faz-Delgado

2016-11-01

Full Text Available In Ecuador Primary Education has as goal to develop the abilities, skills and linguistic competence in children and teenagers from 5 years old until they arrive to High School degree.  High School main objective is to provide to students a general and an interdisciplinary preparation that guide them to elaborate their life projects in order that they can fit in societyas responsible, critical and solidary human beings. It also has as intention to develop students’ abilities in knowledge acquisition and citizen competence and to prepare them to work, to learn and to access to University; this aspect establishes the importance of an adequate professional orientation that facilitates the conscious selection of their future profession and career. This article contains theoretical basis of process the formation and professional’s orientation in the High School, for the attention on the context of the Ecuador people.

General practitioners' decision to refer patients to dietitians: insight into the clinical reasoning process.

Science.gov (United States)

Pomeroy, Sylvia E M; Cant, Robyn P

2010-01-01

The aim of this project was to describe general practitioners' (GPs') decision-making process for reducing nutrition risk in cardiac patients through referring a patient to a dietitian. The setting was primary care practices in Victoria. The method we employed was mixed methods research: in Study 1, 30 GPs were interviewed. Recorded interviews were transcribed and narratives analysed thematically. Study 2 involved a survey of statewide random sample of GPs. Frequencies and analyses of variance were used to explore the impact of demographic variables on decisions to refer. We found that the referral decision involved four elements: (i) synthesising management information; (ii) forecasting outcomes; (iii) planning management; and (iv) actioning referrals. GPs applied cognitive and collaborative strategies to develop a treatment plan. In Study 2, doctors (248 GPs, 30%) concurred with identified barriers/enabling factors for patients' referral. There was no association between GPs' sex, age or hours worked per week and referral factors. We conclude that a GP's judgment to offer a dietetic referral to an adult patient is a four element reasoning process. Attention to how these elements interact may assist clinical decision making. Apart from the sole use of prescribed medications/surgical procedures for cardiac care, patients offered a dietetic referral were those who were considered able to commit to dietary change and who were willing to attend a dietetic consultation. Improvements in provision of patients' nutrition intervention information to GPs are needed. Further investigation is justified to determine how to resolve this practice gap.

The General Aggression Model

NARCIS (Netherlands)

Allen, Johnie J.; Anderson, Craig A.; Bushman, Brad J.

The General Aggression Model (GAM) is a comprehensive, integrative, framework for understanding aggression. It considers the role of social, cognitive, personality, developmental, and biological factors on aggression. Proximate processes of GAM detail how person and situation factors influence

A DG approach to the numerical solution of the Stein-Stein stochastic volatility option pricing model

Science.gov (United States)

Hozman, J.; Tichý, T.

2017-12-01

Stochastic volatility models enable to capture the real world features of the options better than the classical Black-Scholes treatment. Here we focus on pricing of European-style options under the Stein-Stein stochastic volatility model when the option value depends on the time, on the price of the underlying asset and on the volatility as a function of a mean reverting Orstein-Uhlenbeck process. A standard mathematical approach to this model leads to the non-stationary second-order degenerate partial differential equation of two spatial variables completed by the system of boundary and terminal conditions. In order to improve the numerical valuation process for a such pricing equation, we propose a numerical technique based on the discontinuous Galerkin method and the Crank-Nicolson scheme. Finally, reference numerical experiments on real market data illustrate comprehensive empirical findings on options with stochastic volatility.

Application of the generalized multi structural (GMS) wave function to photoelectron spectra and electron scattering processes

International Nuclear Information System (INIS)

Nascimento, M.A.C. do

1992-01-01

A Generalized Multi Structural (GMS) wave function is presented which combines the advantages of the SCF-MO and VB models, preserving the classical chemical structures but optimizing the orbitals in a self-consistent way. This wave function is particularly suitable to treat situations where the description of the molecular state requires localized wave functions. It also provides a very convenient way of treating the electron correlation problem, avoiding large CI expansions. The final wave functions are much more compact and easier to interpret than the ones obtained by the conventional methods, using orthogonal orbitals. Applications of the GMS wave function to the study of the photoelectron spectra of the trans-glyoxal molecule and to electron impact excitation processes in the nitrogen molecule are presented as an illustration of the method. (author)

Associations between Grawe's general mechanisms of change and Young's early maladaptive schemas in psychotherapy research: a comparative study of change processes.

Science.gov (United States)

Mander, Johannes V; Jacob, Gitta A; Götz, Lea; Sammet, Isa; Zipfel, Stephan; Teufel, Martin

2015-01-01

The study aimed at analyzing associations between Grawe's general mechanisms of change and Young's early maladaptive schemas (EMS). Therefore, 98 patients completed the Scale for the Multiperspective Assessment of General Change Mechanisms in Psychotherapy (SACiP), the Young Shema Questionnaire-Short Form Revised (YSQ S3R), and diverse outcome measures at the beginning and end of treatment. Our results are important for clinical applications, as we demonstrated strong predictive effects of change mechanisms on schema domains using regression analyses and cross-lagged panel models. Resource activation experiences seem to be especially crucial in fostering alterations in EMS, as this change mechanism demonstrated significant associations with several schema domains. Future research should investigate these aspects in more detail using observer-based micro-process analyses.

The Generalized Quantum Statistics

OpenAIRE

Hwang, WonYoung; Ji, Jeong-Young; Hong, Jongbae

1999-01-01

The concept of wavefunction reduction should be introduced to standard quantum mechanics in any physical processes where effective reduction of wavefunction occurs, as well as in the measurement processes. When the overlap is negligible, each particle obey Maxwell-Boltzmann statistics even if the particles are in principle described by totally symmetrized wavefunction [P.R.Holland, The Quantum Theory of Motion, Cambridge Unversity Press, 1993, p293]. We generalize the conjecture. That is, par...

A generalized gyrokinetic Poisson solver

International Nuclear Information System (INIS)

Lin, Z.; Lee, W.W.

1995-03-01

A generalized gyrokinetic Poisson solver has been developed, which employs local operations in the configuration space to compute the polarization density response. The new technique is based on the actual physical process of gyrophase-averaging. It is useful for nonlocal simulations using general geometry equilibrium. Since it utilizes local operations rather than the global ones such as FFT, the new method is most amenable to massively parallel algorithms

Tuned with a tune: Talker normalization via general auditory processes

Directory of Open Access Journals (Sweden)

Erika J C Laing

2012-06-01

Full Text Available Voices have unique acoustic signatures, contributing to the acoustic variability listeners must contend with in perceiving speech, and it has long been proposed that listeners normalize speech perception to information extracted from a talker’s speech. Initial attempts to explain talker normalization relied on extraction of articulatory referents, but recent studies of context-dependent auditory perception suggest that general auditory referents such as the long-term average spectrum (LTAS of a talker’s speech similarly affect speech perception. The present study aimed to differentiate the contributions of articulatory/linguistic versus auditory referents for context-driven talker normalization effects and, more specifically, to identify the specific constraints under which such contexts impact speech perception. Synthesized sentences manipulated to sound like different talkers influenced categorization of a subsequent speech target only when differences in the sentences’ LTAS were in the frequency range of the acoustic cues relevant for the target phonemic contrast. This effect was true both for speech targets preceded by spoken sentence contexts and for targets preceded by nonspeech tone sequences that were LTAS-matched to the spoken sentence contexts. Specific LTAS characteristics, rather than perceived talker, predicted the results suggesting that general auditory mechanisms play an important role in effects considered to be instances of perceptual talker normalization.

El Lenguaje de los Chicanos (The Language of Chicanos). Regional and Social Characteristics of Language Used by Mexican Americans.

Science.gov (United States)

Hernandez-Chavez, Eduardo, Ed.; And Others

The following articles are included in this anthology on Chicano speech: (1) "Mexican Spanish," D.N. Cardenas; (2) "The Archaic and the Modern in the Spanish of New Mexico," J. Ornstein; (3) "Problemas Lexicograficos del Espanol del Sudoeste," A.M. Espinosa, Jr.; (4) "Associative Interference in New Mexican Spanish," J.B. Rael; (5) "Some Aspects…

A Study of Intuitive Thinking.

Science.gov (United States)

Goethe, Susan E. A. M.

The development and use of intuitive thinking, at all levels of education, have been of concern to scholars in recent years. This paper discusses the findings and theories of various scholars about intuitive thinking and learning, including the work of Jean Piaget, Jerome Bruner, Richard Jones, and Robert Ornstein. The paper also explores the use…

Teachers' Understanding of Algebraic Generalization

Science.gov (United States)

Hawthorne, Casey Wayne

Generalization has been identified as a cornerstone of algebraic thinking (e.g., Lee, 1996; Sfard, 1995) and is at the center of a rich conceptualization of K-8 algebra (Kaput, 2008; Smith, 2003). Moreover, mathematics teachers are being encouraged to use figural-pattern generalizing tasks as a basis of student-centered instruction, whereby teachers respond to and build upon the ideas that arise from students' explorations of these activities. Although more and more teachers are engaging their students in such generalizing tasks, little is known about teachers' understanding of generalization and their understanding of students' mathematical thinking in this domain. In this work, I addressed this gap, exploring the understanding of algebraic generalization of 4 exemplary 8th-grade teachers from multiple perspectives. A significant feature of this investigation is an examination of teachers' understanding of the generalization process, including the use of algebraic symbols. The research consisted of two phases. Phase I was an examination of the teachers' understandings of the underlying quantities and quantitative relationships represented by algebraic notation. In Phase II, I observed the instruction of 2 of these teachers. Using the lens of professional noticing of students' mathematical thinking, I explored the teachers' enacted knowledge of algebraic generalization, characterizing how it supported them to effectively respond to the needs and queries of their students. Results indicated that teachers predominantly see these figural patterns as enrichment activities, disconnected from course content. Furthermore, in my analysis, I identified conceptual difficulties teachers experienced when solving generalization tasks, in particular, connecting multiple symbolic representations with the quantities in the figures. Moreover, while the teachers strived to overcome the challenges of connecting different representations, they invoked both productive and unproductive

Markov constant and quantum instabilities

Czech Academy of Sciences Publication Activity Database

Pelantová, E.; Starosta, Š.; Znojil, Miloslav

2016-01-01

Roč. 49, č. 15 (2016), s. 155201 ISSN 1751-8113 R&D Projects: GA ČR GA16-22945S Institutional support: RVO:61389005 Keywords : renormalizable quantum theories with ghosts * Pais-Uhlenbeck model * singular spectra * square-well model * number theory analysis * physical applications Subject RIV: BE - Theoretical Physics Impact factor: 1.857, year: 2016

40 CFR 434.11 - General definitions.

Science.gov (United States)

2010-07-01

... General Provisions § 434.11 General definitions. (a) The term “acid or ferruginous mine drainage” means mine drainage which, before any treatment, either has a pH of less than 6.0 or a total iron... processes within a coal preparation plant. (h) The term “mine drainage” means any drainage, and any water...

How to make thermodynamic perturbation theory to be suitable for low temperature?

Science.gov (United States)

Zhou, Shiqi

2009-02-07

Low temperature unsuitability is a problem plaguing thermodynamic perturbation theory (TPT) for years. Present investigation indicates that the low temperature predicament can be overcome by employing as reference system a nonhard sphere potential which incorporates one part of the attractive ingredient in a potential function of interest. In combination with a recently proposed TPT [S. Zhou, J. Chem. Phys. 125, 144518 (2006)] based on a lambda expansion (lambda being coupling parameter), the new perturbation strategy is employed to predict for several model potentials. It is shown that the new perturbation strategy can very accurately predict various thermodynamic properties even if the potential range is extremely short and hence the temperature of interest is very low and current theoretical formalisms seriously deteriorate or critically fail to predict even the existence of the critical point. Extensive comparison with existing liquid state theories and available computer simulation data discloses a superiority of the present TPT to two Ornstein-Zernike-type integral equation theories, i.e., hierarchical reference theory and self-consistent Ornstein-Zernike approximation.

Generalized Nonlinear Yule Models

OpenAIRE

Lansky, Petr; Polito, Federico; Sacerdote, Laura

2016-01-01

With the aim of considering models with persistent memory we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macrovolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth...

DYNSYL: a general-purpose dynamic simulator for chemical processes

International Nuclear Information System (INIS)

Patterson, G.K.; Rozsa, R.B.

1978-01-01

Lawrence Livermore Laboratory is conducting a safeguards program for the Nuclear Regulatory Commission. The goal of the Material Control Project of this program is to evaluate material control and accounting (MCA) methods in plants that handle special nuclear material (SNM). To this end we designed and implemented the dynamic chemical plant simulation program DYNSYL. This program can be used to generate process data or to provide estimates of process performance; it simulates both steady-state and dynamic behavior. The MCA methods that may have to be evaluated range from sophisticated on-line material trackers such as Kalman filter estimators, to relatively simple material balance procedures. This report describes the overall structure of DYNSYL and includes some example problems. The code is still in the experimental stage and revision is continuing

General and special education teachers' relations within teamwork ...

African Journals Online (AJOL)

and instruction, assessment and evaluation, and classroom management and behavior. Typically, the ... teaching techniques and learning processes. ... general objective of this research is to establish the relations of general and special.

Referents that support the Pedagogic Professional Performance Integral General Professor Secondary School, in the use of informatics in the teaching-learning process

Directory of Open Access Journals (Sweden)

Luis Emilio Caro Betancourt

2008-09-01

Full Text Available This article approaches the theoretical referents that sustain the professional pedagogical behavior of the Entire General Professor of Secondary School, using computer science in the teaching learning process. Taking into account the introducti on of the scientific and technical developments (Computer science in education and the professional's role starting from the demands of the conceived model for Secondary School Education.

Quantum-statistical kinetic equations

International Nuclear Information System (INIS)

Loss, D.; Schoeller, H.

1989-01-01

Considering a homogeneous normal quantum fluid consisting of identical interacting fermions or bosons, the authors derive an exact quantum-statistical generalized kinetic equation with a collision operator given as explicit cluster series where exchange effects are included through renormalized Liouville operators. This new result is obtained by applying a recently developed superoperator formalism (Liouville operators, cluster expansions, symmetrized projectors, P q -rule, etc.) to nonequilibrium systems described by a density operator ρ(t) which obeys the von Neumann equation. By means of this formalism a factorization theorem is proven (being essential for obtaining closed equations), and partial resummations (leading to renormalized quantities) are performed. As an illustrative application, the quantum-statistical versions (including exchange effects due to Fermi-Dirac or Bose-Einstein statistics) of the homogeneous Boltzmann (binary collisions) and Choh-Uhlenbeck (triple collisions) equations are derived

The evolution of robotic general surgery.

Science.gov (United States)

Wilson, E B

2009-01-01

Surgical robotics in general surgery has a relatively short but very interesting evolution. Just as minimally invasive and laparoscopic techniques have radically changed general surgery and fractionated it into subspecialization, robotic technology is likely to repeat the process of fractionation even further. Though it appears that robotics is growing more quickly in other specialties, the changes digital platforms are causing in the general surgical arena are likely to permanently alter general surgery. This review examines the evolution of robotics in minimally invasive general surgery looking forward to a time where robotics platforms will be fundamental to elective general surgery. Learning curves and adoption techniques are explored. Foregut, hepatobiliary, endocrine, colorectal, and bariatric surgery will be examined as growth areas for robotics, as well as revealing the current uses of this technology.

Trade liberalization, the Mercosur integration process and the agriculture-industry transfers: a general equilibrium analysis

Directory of Open Access Journals (Sweden)

Joaquim Bento de Souza Ferreira Filho

1999-12-01

Full Text Available This paper deals with the effects of trade liberalization and Mercosur integration process upon the Brazilian economy, with emphasis on the agricultural and agroindustrial production sectors, under the hypothesis that those phenomena could be another step in the rural-urban transfer process in Brazil. The analysis is conducted through an applied general equilibrium model. Results suggest that trade liberalization would hardly generate a widespread process of rural-urban transfers, although Brazilian agriculture shows up as a loser in the process. Notwithstanding that fact, there are transfers inside the agricultural sectors, where, besides the losses in the value added of the grain production sectors, there would be gains for the livestock and for the ''other crops" sectors. The agroindustry, in contrast, seems to gain both in Brazil and Argentina. Model results suggest yet that the Brazilian society would be benefitted as a whole by the integration, despite the losses in the agricultural sector.Este artigo analisa os efeitos do processo de liberalização comercial e de constituição do Mercosul sobre a economia brasileira, com ênfase nos setores produtivos da agricultura e da agroindústria, sob a hipótese de que aqueles fenômenos seriam mais uma etapa no processo de transferências rurais-urbanas no Brasil. Para tanto, a análise é conduzida através do uso de um modelo de equilíbrio geral aplicado. Os resultados sugerem que a integração comercial não irá gerar um processo amplo de transferências rurais-urbanas no Brasil, embora a agricultura brasileira apareça, no agregado, como o setor perdedor na integração, em benefício da agricultura argentina. Há, entretanto, transferências dentro dos setores da agropecuária brasileira, onde, ao lado das perdas no valor adicionado do setor produtor de grãos, haveria ganhos para a pecuária e para o setor ''outras culturas". A agroindústria, em contraste, parece ganhar tanto no Brasil

Generalized rough sets

International Nuclear Information System (INIS)

Rady, E.A.; Kozae, A.M.; Abd El-Monsef, M.M.E.

2004-01-01

The process of analyzing data under uncertainty is a main goal for many real life problems. Statistical analysis for such data is an interested area for research. The aim of this paper is to introduce a new method concerning the generalization and modification of the rough set theory introduced early by Pawlak [Int. J. Comput. Inform. Sci. 11 (1982) 314

A new iteration process for generalized lipschitz pseudo-contractive and generalized lipschitz accretive mappings

International Nuclear Information System (INIS)

Chidume, C.E.; Ofoedu, E.U.

2007-07-01

Let K be a nonempty closed convex subset of a real Banach space E. Let T : K → K be a generalized Lipschitz pseudo-contractive mapping such that F(T) := { x element of K : Tx = x} ≠ 0. Let { α n } n ≥ 1 , { λ n } n ≥ 1 and { θ n } n ≥ 1 be real sequences in (0, 1) such that α n = o( θ n ), lim n →∞ λ n = 0 and λ n ( α n + θ n ) 1 element of K, let the sequence { x n } n ≥ 1 be iteratively generated by x n+1 = (1 - λ n α n )x n + λ n α n Tx n - λ n θ n (x n - x 1 ), n ≥ 1. Then, { x n } n ≥ 1 is bounded. Moreover, if E is a reflexive Banach space with uniformly Gateaux differentiable norm and if Σ n=1 ∞ λ n θ n = ∞ is additionally assumed, then, under mild conditions, left brace# x n } n ≥ 1 converges strongly to some x* element of F(T). (author)

A globally accurate theory for a class of binary mixture models

Science.gov (United States)

Dickman, Adriana G.; Stell, G.

The self-consistent Ornstein-Zernike approximation results for the 3D Ising model are used to obtain phase diagrams for binary mixtures described by decorated models, yielding the plait point, binodals, and closed-loop coexistence curves for the models proposed by Widom, Clark, Neece, and Wheeler. The results are in good agreement with series expansions and experiments.

Studies of Fluctuation Processes in Nuclear Collisions

Energy Technology Data Exchange (ETDEWEB)

Ayik, Sakir [Tennessee Technological Univ., Cookeville, TN (United States). Dept. of Physics

2016-04-14

The standard one-body transport approaches have been extensively applied to investigate heavy-ion collision dynamics at low and intermediate energies. At low energies the approach is the mean-field description of the time-dependent Hartree-Fock (TDHF) theory. At intermediate energies the approach is extended by including a collision term, and its application has been carried out mostly in the semi-classical framework of the Boltzmann-Uhling-Uhlenbeck (BUU) model. The standard transport models provide a good understanding of the average properties of the collision dynamics in terms of the effective interactions in both low and intermediate energies. However, the standard models are inadequate for describing the fluctuation dynamics of collective motion at low energies and disassembling of the nuclear system into fragments at intermediate energies resulting from the growth of density fluctuations in the spinodal region. Our tasks have been to improve the standard transport approaches by incorporating fluctuation mechanisms into the description. There are mainly two different mechanisms for fluctuations: (i) Collisional fluctuations generated by binary nucleon collisions, which provide the dominant mechanism at intermediate energies, and (ii) One-body mechanism or mean-field fluctuations, which is the dominant mechanism at low energies. In the first part of our project, the PI extended the standard transport model at intermediate energies by incorporating collisional mechanism according to the “Generalized Langevin Description” of Mori formalism. The PI and his collaborators carried out a number of applications for describing dynamical mechanism of nuclear multi fragmentations, and nuclear collective response in the semi-classical framework of the approach, which is known as the Boltzmann-Langevin model. In the second part of the project, we considered dynamical description at low energies. Because of the effective Pauli blocking, the collisional dissipation and

On Generalization in Qualitatively Oriented Research

Directory of Open Access Journals (Sweden)

Philipp Mayring

2007-09-01

Full Text Available In this article, I open a debate about the importance and possibilities of generalization in qualitative oriented research. Generalization traditionally is seen as a central aim of science, as a process of theory formulation for further applications. Others criticize the concept in general, either because of the insufficiency of inductive arguments (POPPER, 1959 or because of context specificity of all scientific findings (LINCOLN & GUBA, 1985. In this paper, I argue that generalization is necessary in qualitative research, but we have to differentiate different aims of generalization: laws, rules, context specific statements, similarities and differences, and procedures. There are different possibilities to arrive at a generalization: analysis of total population, falsification, random or stratified samples, argumentative generalization, theoretical sampling, variation, and triangulation. Depending on the type of research or research design some of those strategies of generalization can be important for qualitative oriented research. This is discussed especially in respect to single case analysis. URN: urn:nbn:de:0114-fqs0703262

A hybrid model for the investigation of heavy ion collisions at intermediate energies

International Nuclear Information System (INIS)

Heide, B.M.

1995-09-01

The following topics were dealt with: The coupling of the Botzmann-Uehling-Uhlenbeck (BUU) model with Kopenhagen multifragmentation model realising a new hybrid model, application on 197 Au+ 197 Au reactions between 100 and 250 A.MeV, calculation of the chracteristics of the fragmentation system including mass number, excitation energy, angular momenta, two-particle correlation function

The critical role of social workers in home-based primary care.

Science.gov (United States)

Reckrey, Jennifer M; Gettenberg, Gabrielle; Ross, Helena; Kopke, Victoria; Soriano, Theresa; Ornstein, Katherine

2014-01-01

The growing homebound population has many complex biomedical and psychosocial needs and requires a team-based approach to care (Smith, Ornstein, Soriano, Muller, & Boal, 2006). The Mount Sinai Visiting Doctors Program (MSVD), a large interdisciplinary home-based primary care program in New York City, has a vibrant social work program that is integrated into the routine care of homebound patients. We describe the assessment process used by MSVD social workers, highlight examples of successful social work care, and discuss why social workers' individualized care plans are essential for keeping patients with chronic illness living safely in the community. Despite barriers to widespread implementation, such social work involvement within similar home-based clinical programs is essential in the interdisciplinary care of our most needy patients.

Exploring antihyperons potentials in nuclei by antiproton-nucleon reactions

Energy Technology Data Exchange (ETDEWEB)

Sanchez Lorente, Alicia [Helmholtz Institut Mainz (Germany); Collaboration: PANDA-Collaboration

2015-07-01

The exclusive production of hyperon-Antihyperon pairs close to their production threshold in antiproton-nucleus collisions offers a unique and hitherto unexplored opportunity to study the behaviour of Antihyperons in nuclei. For the first time we analyse these reactions in a microscopic transport model using the Giessen Boltzmann-Uehling-Uhlenbeck Transportmodel (GiBUU). We find a substantial sensitivity of transverse momentum correlations of coincident AntiLambda-Lambda-pairs to the assumed depth of the AntiLambda potential. Rather than diminishing this effect, secondary scattering effects which are more pronounced at deeper AntiLambda potentials enhance this sensitivity. Because of the high cross section for this process and the simplicity of this method our results pave the way for experimental studies at the FAIR facility.

Categorization = Decision Making + Generalization

Science.gov (United States)

Seger, Carol A; Peterson, Erik J.

2013-01-01

We rarely, if ever, repeatedly encounter exactly the same situation. This makes generalization crucial for real world decision making. We argue that categorization, the study of generalizable representations, is a type of decision making, and that categorization learning research would benefit from approaches developed to study the neuroscience of decision making. Similarly, methods developed to examine generalization and learning within the field of categorization may enhance decision making research. We first discuss perceptual information processing and integration, with an emphasis on accumulator models. We then examine learning the value of different decision making choices via experience, emphasizing reinforcement learning modeling approaches. Next we discuss how value is combined with other factors in decision making, emphasizing the effects of uncertainty. Finally, we describe how a final decision is selected via thresholding processes implemented by the basal ganglia and related regions. We also consider how memory related functions in the hippocampus may be integrated with decision making mechanisms and contribute to categorization. PMID:23548891

Consultant-led, multidisciplinary balance clinic: process evaluation of a specialist model of care in a district general hospital.

Science.gov (United States)

Trinidade, A; Yung, M W

2014-04-01

A specialist balance clinic to effectively deal with dizzy patients is recommended by ENT-UK. We audit the patient pathway before and following the introduction of a consultant-led dedicated balance clinic. Process evaluation and audit. ENT outpatients department of a district general hospital. The journey of dizzy patients seen in the general ENT clinic was mapped from case notes and recorded retrospectively. A consultant-led, multidisciplinary balance clinic involving an otologist, a senior audiologist and a neurophysiotherapist was then set up, and the journey was prospectively recorded and compared with that before the change. Of the 44 dizzy patients seen in the general clinic, 41% had further follow-up consultations; 64% were given definitive or provisional diagnoses; 75% were discharged without a management plan. Oculomotor examination was not systematically performed. The mean interval between Visits 1 and 2 was 8.4 weeks and the mean number of visits was 3. In the consultant-led dedicated balance clinic, following Visit 1, only 8% of patients required follow-up; 97% received definitive diagnoses, which guided management; all patients left with definitive management plans in place. In all patients, oculomotor assessment was systematically performed and all patients received consultant and, where necessary, allied healthcare professional input. By standardising the management experience for dizzy patients, appropriate and timely treatment can be achieved, allowing for a more seamless and efficient patient journey from referral to treatment. A multidisciplinary balance clinic led by a consultant otologist is the ideal way to achieve this. © 2014 John Wiley & Sons Ltd.

Experienced General Music Teachers' Instructional Decision Making

Science.gov (United States)

Johnson, Daniel C.; Matthews, Wendy K.

2017-01-01

The purpose of this descriptive study was to explore experienced general music teachers' decision-making processes. Participants included seven experienced, American general music teachers who contributed their views during two phases of data collection: (1) responses to three classroom scenarios; and (2) in-depth, semi-structured, follow-up…

A General Representation Theorem for Integrated Vector Autoregressive Processes

DEFF Research Database (Denmark)

Franchi, Massimo

We study the algebraic structure of an I(d) vector autoregressive process, where d is restricted to be an integer. This is useful to characterize its polynomial cointegrating relations and its moving average representation, that is to prove a version of the Granger representation theorem valid...

Glauber model and its generalizations

International Nuclear Information System (INIS)

Bialkowski, G.

The physical aspects of the Glauber model problems are studied: potential model, profile function and Feynman diagrams approaches. Different generalizations of the Glauber model are discussed: particularly higher and lower energy processes and large angles [fr

A generalized perturbation program for CANDU reactor

Energy Technology Data Exchange (ETDEWEB)

Kim, Do Heon; Kim, Jong Kyung [Hanyang University, Seoul (Korea, Republic of); Choi, Hang Bok; Roh, Gyu Hong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Yang, Won Sik [Chosun University, Kwangju (Korea, Republic of)

1999-12-31

A generalized perturbation program has been developed for the purpose of estimating zonal power variation of a CANDU reactor upon refueling operation. The forward and adjoint calculation modules of RFSP code were used to construct the generalized perturbation program. The numerical algorithm for the generalized adjoint flux calculation was verified by comparing the zone power estimates upon refueling with those of forward calculation. It was, however, noticed that the truncation error from the iteration process of the generalized adjoint flux is not negligible. 2 refs., 1 figs., 1 tab. (Author)

A generalized perturbation program for CANDU reactor

Energy Technology Data Exchange (ETDEWEB)

Kim, Do Heon; Kim, Jong Kyung [Hanyang University, Seoul (Korea, Republic of); Choi, Hang Bok; Roh, Gyu Hong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Yang, Won Sik [Chosun University, Kwangju (Korea, Republic of)

1998-12-31

A generalized perturbation program has been developed for the purpose of estimating zonal power variation of a CANDU reactor upon refueling operation. The forward and adjoint calculation modules of RFSP code were used to construct the generalized perturbation program. The numerical algorithm for the generalized adjoint flux calculation was verified by comparing the zone power estimates upon refueling with those of forward calculation. It was, however, noticed that the truncation error from the iteration process of the generalized adjoint flux is not negligible. 2 refs., 1 figs., 1 tab. (Author)

Generalized Boolean logic Driven Markov Processes: A powerful modeling framework for Model-Based Safety Analysis of dynamic repairable and reconfigurable systems

International Nuclear Information System (INIS)

Piriou, Pierre-Yves; Faure, Jean-Marc; Lesage, Jean-Jacques

2017-01-01

This paper presents a modeling framework that permits to describe in an integrated manner the structure of the critical system to analyze, by using an enriched fault tree, the dysfunctional behavior of its components, by means of Markov processes, and the reconfiguration strategies that have been planned to ensure safety and availability, with Moore machines. This framework has been developed from BDMP (Boolean logic Driven Markov Processes), a previous framework for dynamic repairable systems. First, the contribution is motivated by pinpointing the limitations of BDMP to model complex reconfiguration strategies and the failures of the control of these strategies. The syntax and semantics of GBDMP (Generalized Boolean logic Driven Markov Processes) are then formally defined; in particular, an algorithm to analyze the dynamic behavior of a GBDMP model is developed. The modeling capabilities of this framework are illustrated on three representative examples. Last, qualitative and quantitative analysis of GDBMP models highlight the benefits of the approach.

Quantum Networks: General theory and applications

International Nuclear Information System (INIS)

Bisio, A.; D'Ariano, G. M.; Perinotti, P.; Chiribella, G.

2011-01-01

In this work we present a general mathematical framework to deal with Quantum Networks, i.e. networks resulting from the interconnection of elementary quantum circuits. The cornerstone of our approach is a generalization of the Choi isomorphism that allows one to efficiently represent any given Quantum Network in terms of a single positive operator. Our formalism allows one to face and solve many quantum information processing problems that would be hardly manageable otherwise, the most relevant of which are reviewed in this work: quantum process tomography, quantum cloning and learning of transformations, inversion of a unitary gate, information-disturbance tradeoff in estimating a unitary transformation, cloning and learning of a measurement device (Authors)

Study and discretization of kinetic models and fluid models at low Mach number

International Nuclear Information System (INIS)

Dellacherie, Stephane

2011-01-01

This thesis summarizes our work between 1995 and 2010. It concerns the analysis and the discretization of Fokker-Planck or semi-classical Boltzmann kinetic models and of Euler or Navier-Stokes fluid models at low Mach number. The studied Fokker-Planck equation models the collisions between ions and electrons in a hot plasma, and is here applied to the inertial confinement fusion. The studied semi-classical Boltzmann equations are of two types. The first one models the thermonuclear reaction between a deuterium ion and a tritium ion producing an α particle and a neutron particle, and is also in our case used to describe inertial confinement fusion. The second one (known as the Wang-Chang and Uhlenbeck equations) models the transitions between electronic quantified energy levels of uranium and iron atoms in the AVLIS isotopic separation process. The basic properties of these two Boltzmann equations are studied, and, for the Wang-Chang and Uhlenbeck equations, a kinetic-fluid coupling algorithm is proposed. This kinetic-fluid coupling algorithm incited us to study the relaxation concept for gas and immiscible fluids mixtures, and to underline connections with classical kinetic theory. Then, a diphasic low Mach number model without acoustic waves is proposed to model the deformation of the interface between two immiscible fluids induced by high heat transfers at low Mach number. In order to increase the accuracy of the results without increasing computational cost, an AMR algorithm is studied on a simplified interface deformation model. These low Mach number studies also incited us to analyse on cartesian meshes the inaccuracy at low Mach number of Godunov schemes. Finally, the LBM algorithm applied to the heat equation is justified

Generalized File Management System or Proto-DBMS?

Science.gov (United States)

Braniff, Tom

1979-01-01

The use of a data base management system (DBMS) as opposed to traditional data processing is discussed. The generalized file concept is viewed as an entry level step to the DBMS. The transition process from one system to the other is detailed. (SF)

Accreditation in general practice in Denmark

DEFF Research Database (Denmark)

Andersen, Merethe K; Pedersen, Line B; Siersma, Volkert

2017-01-01

Background: Accreditation is used increasingly in health systems worldwide. However, there is a lack of evidence on the effects of accreditation, particularly in general practice. In 2016 a mandatory accreditation scheme was initiated in Denmark, and during a 3-year period all practices, as default...... general practitioners in Denmark. Practices allocated to accreditation in 2016 serve as the intervention group, and practices allocated to accreditation in 2018 serve as controls. The selected outcomes should meet the following criteria: (1) a high degree of clinical relevance; (2) the possibility...... practice and mortality. All outcomes relate to quality indicators included in the Danish Healthcare Quality Program, which is based on general principles for accreditation. Discussion: The consequences of accreditation and standard-setting processes are generally under-researched, particularly in general...

General principles of the quality management

International Nuclear Information System (INIS)

Koutaniemi, P.

2005-01-01

The objective of the presentation is to outline some general infrastructure of nuclear industry with regard to the quality management; to emphasise significance of safety management as an integral part of the quality management; and to highlight different steps of the management process in a near-time working, at an annual level and as a strategic process

A general audiovisual temporal processing deficit in adult readers with dyslexia

NARCIS (Netherlands)

Francisco, A.A.; Jesse, A.; Groen, M.A.; McQueen, J.M.

2017-01-01

Purpose: Because reading is an audiovisual process, reading impairment may reflect an audiovisual processing deficit. The aim of the present study was to test the existence and scope of such a deficit in adult readers with dyslexia. Method: We tested 39 typical readers and 51 adult readers with

Regeneration and general Markov chains

Directory of Open Access Journals (Sweden)

Vladimir V. Kalashnikov

1994-01-01

Full Text Available Ergodicity, continuity, finite approximations and rare visits of general Markov chains are investigated. The obtained results permit further quantitative analysis of characteristics, such as, rates of convergence, continuity (measured as a distance between perturbed and non-perturbed characteristics, deviations between Markov chains, accuracy of approximations and bounds on the distribution function of the first visit time to a chosen subset, etc. The underlying techniques use the embedding of the general Markov chain into a wide sense regenerative process with the help of splitting construction.

The theory, practice, and future of process improvement in general thoracic surgery.

Science.gov (United States)

Freeman, Richard K

2014-01-01

Process improvement, in its broadest sense, is the analysis of a given set of actions with the aim of elevating quality and reducing costs. The tenets of process improvement have been applied to medicine in increasing frequency for at least the last quarter century including thoracic surgery. This review outlines the theory underlying process improvement, the currently available data sources for process improvement and possible future directions of research. Copyright © 2015 Elsevier Inc. All rights reserved.

Cognitive load and emotional processing in generalized anxiety disorder: electrocortical evidence for increased distractibility.

Science.gov (United States)

MacNamara, Annmarie; Proudfit, Greg Hajcak

2014-08-01

Generalized anxiety disorder (GAD) may be characterized by emotion regulation deficits attributable to an imbalance between top-down (i.e., goal-driven) and bottom-up (i.e., stimulus-driven) attention. In prior work, these attentional processes were examined by presenting unpleasant and neutral pictures within a working memory paradigm. The late positive potential (LPP) measured attention toward task-irrelevant pictures. Results from this prior work showed that working memory load reduced the LPP across participants; however, this effect was attenuated for individuals with greater self-reported state anxiety, suggesting reduced top-down control. In the current study, the same paradigm was used with 106 medication-free female participants-71 with GAD and 35 without GAD. Unpleasant pictures elicited larger LPPs, and working memory load reduced the picture-elicited LPP. Compared with healthy controls, participants with GAD showed large LPPs to unpleasant pictures presented under high working memory load. Self-reported symptoms of anhedonic depression were related to a reduced effect of working memory load on the LPP elicited by neutral pictures. These results indicate that individuals with GAD show less flexible modulation of attention when confronted with unpleasant stimuli. Furthermore, among those with GAD, anhedonic depression may broaden attentional deficits to neutral distracters. (c) 2014 APA, all rights reserved.

Nigerian Journal of General Practice: About this journal

African Journals Online (AJOL)

Policies. » Focus and Scope; » Section Policies; » Peer Review Process; » Publication Frequency; » Subscriptions; » The Association of General and Private Medical Practitioners of Nigeria [AGPMPN]; » Advertising in the Nigerian Journal of General Practice; » NJGP Editorial Board ...

Susceptibility and magnetization of a random Ising model

Energy Technology Data Exchange (ETDEWEB)

Kumar, D; Srivastava, V [Roorkee Univ. (India). Dept. of Physics

1977-08-01

The susceptibility of a bond disordered Ising model is calculated by configurationally averaging an Ornstein-Zernike type of equation for the two spin correlation function. The equation for the correlation function is derived using a diagrammatic method due to Englert. The averaging is performed using bond CPA. The magnetization is also calculated by averaging in a similar manner a linearised molecular field equation.

'It Opened My Eyes'-examining the impact of a multifaceted chlamydia testing intervention on general practitioners using Normalization Process Theory.

Science.gov (United States)

Yeung, Anna; Hocking, Jane; Guy, Rebecca; Fairley, Christopher K; Smith, Kirsty; Vaisey, Alaina; Donovan, Basil; Imrie, John; Gunn, Jane; Temple-Smith, Meredith

2018-03-28

Chlamydia is the most common notifiable sexually transmissible infection in Australia. Left untreated, it can develop into pelvic inflammatory disease and infertility. The majority of notifications come from general practice and it is ideally situated to test young Australians. The Australian Chlamydia Control Effectiveness Pilot (ACCEPt) was a multifaceted intervention that aimed to reduce chlamydia prevalence by increasing testing in 16- to 29-year-olds attending general practice. GPs were interviewed to describe the effectiveness of the ACCEPt intervention in integrating chlamydia testing into routine practice using Normalization Process Theory (NPT). GPs were purposively selected based on age, gender, geographic location and size of practice at baseline and midpoint. Interview data were analysed regarding the intervention components and results were interpreted using NPT. A total of 44 GPs at baseline and 24 at midpoint were interviewed. Most GPs reported offering a test based on age at midpoint versus offering a test based on symptoms or patient request at baseline. Quarterly feedback was the most significant ACCEPt component for facilitating a chlamydia test. The ACCEPt intervention has been able to moderately normalize chlamydia testing among GPs, although the components had varying levels of effectiveness. NPT can demonstrate the effective implementation of an intervention in general practice and has been valuable in understanding which components are essential and which components can be improved upon.

Definition of Nonequilibrium Entropy of General Systems

OpenAIRE

Mei, Xiaochun

1999-01-01

The definition of nonequilibrium entropy is provided for the general nonequilibrium processes by connecting thermodynamics with statistical physics, and the principle of entropy increment in the nonequilibrium processes is also proved in the paper. The result shows that the definition of nonequilibrium entropy is not unique.

CO-PRODUCT ENHANCEMENT AND DEVELOPMENT FOR THE MASADA OXYNOL PROCESS PROCESS

Energy Technology Data Exchange (ETDEWEB)

Donald V. Watkins

2010-06-14

The focus of this project was an overall process improvement through the enhancement of the co-product streams. The enhancement of the process operations and co-products will increase both ethanol production and the value of other process outputs and reduces the amount of waste byproducts. This leads to a more economical and environmentally sound alternative to landfill disposal of municipal solid waste (MSW). These enhancements can greatly increase the commercial potential for the production of ethanol from MSW by the Masada CES OxyNol process. Both technological and economical issues were considered for steps throughout the conversion process. The research efforts of this project are varied but synergistic. The project investigated many of the operations involved in the Masada process with the overall goal of process improvements. The general goal of the testing was to improve co-product quality, improve conversions efficiencies, minimize process losses, increase energy efficiency, and mitigate process and commercialization risks. The project was divided into 16 subtasks as described in general terms below. All these tasks are interrelated but not necessarily interdependent.

A Generalized Polynomial Chaos-Based Approach to Analyze the Impacts of Process Deviations on MEMS Beams.

Science.gov (United States)

Gao, Lili; Zhou, Zai-Fa; Huang, Qing-An

2017-11-08

A microstructure beam is one of the fundamental elements in MEMS devices like cantilever sensors, RF/optical switches, varactors, resonators, etc. It is still difficult to precisely predict the performance of MEMS beams with the current available simulators due to the inevitable process deviations. Feasible numerical methods are required and can be used to improve the yield and profits of the MEMS devices. In this work, process deviations are considered to be stochastic variables, and a newly-developed numerical method, i.e., generalized polynomial chaos (GPC), is applied for the simulation of the MEMS beam. The doubly-clamped polybeam has been utilized to verify the accuracy of GPC, compared with our Monte Carlo (MC) approaches. Performance predictions have been made on the residual stress by achieving its distributions in GaAs Monolithic Microwave Integrated Circuit (MMIC)-based MEMS beams. The results show that errors are within 1% for the results of GPC approximations compared with the MC simulations. Appropriate choices of the 4-order GPC expansions with orthogonal terms have also succeeded in reducing the MC simulation labor. The mean value of the residual stress, concluded from experimental tests, shares an error about 1.1% with that of the 4-order GPC method. It takes a probability around 54.3% for the 4-order GPC approximation to attain the mean test value of the residual stress. The corresponding yield occupies over 90 percent around the mean within the twofold standard deviations.

A Generalized Polynomial Chaos-Based Approach to Analyze the Impacts of Process Deviations on MEMS Beams

Directory of Open Access Journals (Sweden)

Lili Gao

2017-11-01

Full Text Available A microstructure beam is one of the fundamental elements in MEMS devices like cantilever sensors, RF/optical switches, varactors, resonators, etc. It is still difficult to precisely predict the performance of MEMS beams with the current available simulators due to the inevitable process deviations. Feasible numerical methods are required and can be used to improve the yield and profits of the MEMS devices. In this work, process deviations are considered to be stochastic variables, and a newly-developed numerical method, i.e., generalized polynomial chaos (GPC, is applied for the simulation of the MEMS beam. The doubly-clamped polybeam has been utilized to verify the accuracy of GPC, compared with our Monte Carlo (MC approaches. Performance predictions have been made on the residual stress by achieving its distributions in GaAs Monolithic Microwave Integrated Circuit (MMIC-based MEMS beams. The results show that errors are within 1% for the results of GPC approximations compared with the MC simulations. Appropriate choices of the 4-order GPC expansions with orthogonal terms have also succeeded in reducing the MC simulation labor. The mean value of the residual stress, concluded from experimental tests, shares an error about 1.1% with that of the 4-order GPC method. It takes a probability around 54.3% for the 4-order GPC approximation to attain the mean test value of the residual stress. The corresponding yield occupies over 90 percent around the mean within the twofold standard deviations.

The General Aggression Model.

Science.gov (United States)

Allen, Johnie J; Anderson, Craig A; Bushman, Brad J

2018-02-01

The General Aggression Model (GAM) is a comprehensive, integrative, framework for understanding aggression. It considers the role of social, cognitive, personality, developmental, and biological factors on aggression. Proximate processes of GAM detail how person and situation factors influence cognitions, feelings, and arousal, which in turn affect appraisal and decision processes, which in turn influence aggressive or nonaggressive behavioral outcomes. Each cycle of the proximate processes serves as a learning trial that affects the development and accessibility of aggressive knowledge structures. Distal processes of GAM detail how biological and persistent environmental factors can influence personality through changes in knowledge structures. GAM has been applied to understand aggression in many contexts including media violence effects, domestic violence, intergroup violence, temperature effects, pain effects, and the effects of global climate change. Copyright © 2017 Elsevier Ltd. All rights reserved.

A General Audiovisual Temporal Processing Deficit in Adult Readers with Dyslexia

Science.gov (United States)

Francisco, Ana A.; Jesse, Alexandra; Groen, Margriet A.; McQueen, James M.

2017-01-01

Purpose: Because reading is an audiovisual process, reading impairment may reflect an audiovisual processing deficit. The aim of the present study was to test the existence and scope of such a deficit in adult readers with dyslexia. Method: We tested 39 typical readers and 51 adult readers with dyslexia on their sensitivity to the simultaneity of…

19 CFR 210.27 - General provisions governing discovery.

Science.gov (United States)

2010-04-01

... 19 Customs Duties 3 2010-04-01 2010-04-01 false General provisions governing discovery. 210.27 Section 210.27 Customs Duties UNITED STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND ENFORCEMENT Discovery and Compulsory Process § 210.27 General...

Processing of FRG high-temperature gas-cooled reactor fuel elements at General Atomic under the US/FRG cooperative agreement for spent fuel elements

International Nuclear Information System (INIS)

Holder, N.D.; Strand, J.B.; Schwarz, F.A.; Drake, R.N.

1981-11-01

The Federal Republic of Germany (FRG) and the United States (US) are cooperating on certain aspects of gas-cooled reactor technology under an umbrella agreement. Under the spent fuel treatment development section of the agreement, both FRG mixed uranium/ thorium and low-enriched uranium fuel spheres have been processed in the Department of Energy-sponsored cold pilot plant for high-temperature gas-cooled reactor (HTGR) fuel processing at General Atomic Company in San Diego, California. The FRG fuel spheres were crushed and burned to recover coated fuel particles suitable for further treatment for uranium recovery. Successful completion of the tests described in this paper demonstrated certain modifications to the US HTGR fuel burining process necessary for FRG fuel treatment. Results of the tests will be used in the design of a US/FRG joint prototype headend facility for HTGR fuel

Maltreatment and Delinquency in China: Examining and Extending the Intervening Process of General Strain Theory.

Science.gov (United States)

Gao, Yunjiao; Wong, Dennis S W; Yu, Yanping

2016-01-01

Using a sample of 1,163 adolescents from four middle schools in China, this study explores the intervening process of how adolescent maltreatment is related to delinquency within the framework of general strain theory (GST) by comparing two models. The first model is Agnew's integrated model of GST, which examines the mediating effects of social control, delinquent peer affiliation, state anger, and depression on the relationship between maltreatment and delinquency. Based on this model, with the intent to further explore the mediating effects of state anger and depression and to investigate whether their effects on delinquency can be demonstrated more through delinquent peer affiliation and social control, an extended model (Model 2) is proposed by the authors. The second model relates state anger to delinquent peer affiliation and state depression to social control. By comparing the fit indices and the significance of the hypothesized paths of the two models, the study found that the extended model can better reflect the mechanism of how maltreatment contributes to delinquency, whereas the original integrated GST model only receives partial support because of its failure to find the mediating effects of state negative emotions. © The Author(s) 2014.