Hidden Variables or Positive Probabilities?
Rothman, T; Rothman, Tony
2001-01-01
Despite claims that Bell's inequalities are based on the Einstein locality condition, or equivalent, all derivations make an identical mathematical assumption: that local hidden-variable theories produce a set of positive-definite probabilities for detecting a particle with a given spin orientation. The standard argument is that because quantum mechanics assumes that particles are emitted in a superposition of states the theory cannot produce such a set of probabilities. We examine a paper by Eberhard who claims to show that a generalized Bell inequality, the CHSH inequality, can be derived solely on the basis of the locality condition, without recourse to hidden variables. We point out that he nonetheless assumes a set of positive-definite probabilities, which supports the claim that hidden variables or "locality" is not at issue here, positive-definite probabilities are. We demonstrate that quantum mechanics does predict a set of probabilities that violate the CHSH inequality; however these probabilities ar...
Hidden variables and hidden time in quantum theory
Kurakin, Pavel V.
2005-01-01
Bell's theorem proves only that hidden variables evolving in true physical time can't exist; still the theorem's meaning is usually interpreted intolerably wide. The concept of hidden time (and, in general, hidden space-time) is introduced. Such concept provides a whole new class of physical theories, fully compatible with current knowledge, but giving new tremendous possibilities. Those theories do not violate Bell's theorem.
Hidden attractors in dynamical systems
Dudkowski, Dawid; Jafari, Sajad; Kapitaniak, Tomasz; Kuznetsov, Nikolay V.; Leonov, Gennady A.; Prasad, Awadhesh
2016-06-01
Complex dynamical systems, ranging from the climate, ecosystems to financial markets and engineering applications typically have many coexisting attractors. This property of the system is called multistability. The final state, i.e., the attractor on which the multistable system evolves strongly depends on the initial conditions. Additionally, such systems are very sensitive towards noise and system parameters so a sudden shift to a contrasting regime may occur. To understand the dynamics of these systems one has to identify all possible attractors and their basins of attraction. Recently, it has been shown that multistability is connected with the occurrence of unpredictable attractors which have been called hidden attractors. The basins of attraction of the hidden attractors do not touch unstable fixed points (if exists) and are located far away from such points. Numerical localization of the hidden attractors is not straightforward since there are no transient processes leading to them from the neighborhoods of unstable fixed points and one has to use the special analytical-numerical procedures. From the viewpoint of applications, the identification of hidden attractors is the major issue. The knowledge about the emergence and properties of hidden attractors can increase the likelihood that the system will remain on the most desirable attractor and reduce the risk of the sudden jump to undesired behavior. We review the most representative examples of hidden attractors, discuss their theoretical properties and experimental observations. We also describe numerical methods which allow identification of the hidden attractors.
Hidden Variable Theories and Quantum Nonlocality
Boozer, A. D.
2009-01-01
We clarify the meaning of Bell's theorem and its implications for the construction of hidden variable theories by considering an example system consisting of two entangled spin-1/2 particles. Using this example, we present a simplified version of Bell's theorem and describe several hidden variable theories that agree with the predictions of…
A survey of hidden-variables theories
Belinfante, F J
1973-01-01
A Survey of Hidden-Variables Theories is a three-part book on the hidden-variable theories, referred in this book as """"theories of the first kind"""". Part I reviews the motives in developing different types of hidden-variables theories. The quest for determinism led to theories of the first kind; the quest for theories that look like causal theories when applied to spatially separated systems that interacted in the past led to theories of the second kind. Parts II and III further describe the theories of the first kind and second kind, respectively. This book is written to make the literat
Fujikawa, Kazuo
2013-01-01
Hidden-variables models are critically reassessed. It is first examined if the quantum discord is classically described by the hidden-variable model of Bell in the Hilbert space with $d=2$. The criterion of vanishing quantum discord is related to the notion of reduction and, surprisingly, the hidden-variable model in $d=2$, which has been believed to be consistent so far, is in fact inconsistent and excluded by the analysis of conditional measurement and reduction. The description of the full contents of quantum discord by the deterministic hidden-variables models is not possible. We also re-examine CHSH inequality. It is shown that the well-known prediction of CHSH inequality $|B|\\leq 2$ for the CHSH operator $B$ introduced by Cirel'son is not unique. This non-uniqueness arises from the failure of linearity condition in the non-contextual hidden-variables model in $d=4$ used by Bell and CHSH, in agreement with Gleason's theorem which excludes $d=4$ non-contextual hidden-variables models. If one imposes the l...
Foundational Forces & Hidden Variables in Technology Commercialization
Barnett, Brandon
2011-03-01
The science of physics seems vastly different from the process of technology commercialization. Physics strives to understand our world through the experimental deduction of immutable laws and dependent variables and the resulting macro-scale phenomenon. In comparison, the~goal of business is to make a profit by addressing the needs, preferences, and whims of individuals in a market. It may seem that this environment is too dynamic to identify all the hidden variables and deduct the foundational forces that impact a business's ability to commercialize innovative technologies. One example of a business ``force'' is found in the semiconductor industry. In 1965, Intel co-founder Gordon Moore predicted that the number of transistors incorporated in a chip will approximately double every 24 months. Known as Moore's Law, this prediction has become the guiding principle for the semiconductor industry for the last 40 years. Of course, Moore's Law is not really a law of nature; rather it is the result of efforts by Intel and the entire semiconductor industry. A closer examination suggests that there are foundational principles of business that underlie the macro-scale phenomenon of Moore's Law. Principles of profitability, incentive, and strategic alignment have resulted in a coordinated influx of resources that has driven technologies to market, increasing the profitability of the semiconductor industry and optimizing the fitness of its participants. New innovations in technology are subject to these same principles. So, in addition to traditional market forces, these often unrecognized forces and variables create challenges for new technology commercialization. In this talk, I will draw from ethnographic research, complex adaptive theory, and industry data to suggest a framework with which to think about new technology commercialization. Intel's bio-silicon initiative provides a case study.
Hidden Variables and Placebo Effects
Goradia, Shantilal
2006-03-01
God's response to prayers and placebo leads to a question. How does He respond deterministically? He may be controlling at least one of the two variables of the uncertainty principle by extending His invisible soul to each body particle locally. Amazingly, many Vedic verses support this answer. One describes the size of the soul as arithmetically matching the size of the nucleons as if a particle is a soul. One gives a name meaning particle soul (anu-atma), consistent with particle's indeterministic behavior like that of (soulful) bird’s flying in any directions irrespective of the direction of throw. One describes souls as eternal consistent with the conservation of baryon number. One links the souls to the omnipresent (param- atma) like Einstein Rosen bridges link particles to normal spacetime. One claims eternal coexistence of matter and soul as is inflationary universe in physics/0210040 V2. The implicit scientific consistency of such verses makes the relationship of particle source of consciousness to the omnipresent Supreme analogous to the relationship of quantum source of gravitons in my gr-qc/0507130 to normal spacetime This frees us from the postulation of quantum wormholes and quantum foam. Dr. Hooft's view in ``Does God play dice,'' Physicsword, Dec 2005 seems consistent with my progressive conference presentations in Russia, Europe, India, and USA (Hindu University) in 2004/05. I see implications for nanoscience.
A Bell-type Theorem Without Hidden Variables
Stapp, Henry P
2002-01-01
Bell's theorem rules out local hidden-variable theories. The locality condition is the demand that what an experimenter freely chooses to measure in one space-time region has no influence in a second space-time region that is spacelike separated from the first. The hidden-variable stipulation means that this demand is implemented through requirements on an assumed-to-exist substructure involving hidden variables. The question thus arises whether the locality condition itself fails, or only its implementation by means of the assumed hidden-variable structure. This paper shows that any theory that satisfies two generally accepted features of orthodox quantum theory and that yields certain predictions of quantum theory cannot satisfy the afore-mentioned locality condition. These two features are that the choices made by the experimenters can be treated as localized free variables and that such free choices do not affect outcomes that have already occurred.
Local clustering in scale-free networks with hidden variables.
van der Hofstad, Remco; Janssen, A J E M; van Leeuwaarden, Johan S H; Stegehuis, Clara
2017-02-01
We investigate the presence of triangles in a class of correlated random graphs in which hidden variables determine the pairwise connections between vertices. The class rules out self-loops and multiple edges. We focus on the regime where the hidden variables follow a power law with exponent τ∈(2,3), so that the degrees have infinite variance. The natural cutoff h_{c} characterizes the largest degrees in the hidden variable models, and a structural cutoff h_{s} introduces negative degree correlations (disassortative mixing) due to the infinite-variance degrees. We show that local clustering decreases with the hidden variable (or degree). We also determine how the average clustering coefficient C scales with the network size N, as a function of h_{s} and h_{c}. For scale-free networks with exponent 2vanish only for networks as large as N=10^{9}.
Faculty Meetings: Hidden Conversational Dynamics
Bowman, Richard F.
2015-01-01
In the everydayness of faculty meetings, collegial conversations mirror distinctive dynamics and practices, which either enhance or undercut organizational effectiveness. A cluster of conversational practices affect how colleagues connect, engage, interact, and influence others during faculty meetings in diverse educational settings. The…
Towards gauge unified, supersymmetric hidden strong dynamics
Chiang, Cheng-Wei; Ye, Fang
2016-01-01
We consider a class of models with extra complex scalars that are charged under both the Standard Model and a hidden strongly coupled $SU(N)_H$ gauge sector, and discuss the scenarios where the new scalars are identified as the messenger fields that mediate the spontaneously broken supersymmetries from the hidden sector to the visible sector. The new scalars are embedded into 5-plets and 10-plets of an $SU(5)_V$ gauge group that potentially unifies the Standard Model gauge groups. They also form a tower of bound states via hidden strong dynamics around the TeV scale. The Higgs bosons remain as elementary particles. Quadratically divergent contributions to the Higgs mass from the Standard Model fermions are canceled by the new scalar contributions to alleviate the fine-tuning problem. We also discuss a supersymmetrized version of this class of models, consisting of the minimal supersymmetric Standard Model plus extra chiral multiplets where the new scalars reside. Due to the hidden strong force, the new low-en...
Bardeen variables and hidden gauge symmetries in linearized massive gravity
Jaccard, Maud; Mitsou, Ermis
2012-01-01
We give a detailed discussion of the use of the (3+1) decomposition and of Bardeen's variables in massive gravity linearized over a Minkowski as well as over a de Sitter background. In Minkowski space the Bardeen "potential" \\Phi, that in the massless case is a non-radiative degree of freedom, becomes radiative and describes the helicity-0 component of the massive graviton. Its dynamics is governed by a simple Klein-Gordon action, supplemented by a term (\\Box \\Phi)^2 if we do not make the Fierz-Pauli tuning of the mass term. In de Sitter the identification of the variable that describes the radiative degree of freedom in the scalar sector is more subtle, and even involves expressions non-local in time. The use of this new variable provides a simple and transparent derivation of the Higuchi bound and of the disappearance of the scalar degree of freedom at a special value of $m_g^2/H^2$. The use of this formalism also allows us to uncover the existence of a hidden gauge symmetry of the massive theory, that beco...
Inferring topologies of complex networks with hidden variables.
Wu, Xiaoqun; Wang, Weihan; Zheng, Wei Xing
2012-10-01
Network topology plays a crucial role in determining a network's intrinsic dynamics and function, thus understanding and modeling the topology of a complex network will lead to greater knowledge of its evolutionary mechanisms and to a better understanding of its behaviors. In the past few years, topology identification of complex networks has received increasing interest and wide attention. Many approaches have been developed for this purpose, including synchronization-based identification, information-theoretic methods, and intelligent optimization algorithms. However, inferring interaction patterns from observed dynamical time series is still challenging, especially in the absence of knowledge of nodal dynamics and in the presence of system noise. The purpose of this work is to present a simple and efficient approach to inferring the topologies of such complex networks. The proposed approach is called "piecewise partial Granger causality." It measures the cause-effect connections of nonlinear time series influenced by hidden variables. One commonly used testing network, two regular networks with a few additional links, and small-world networks are used to evaluate the performance and illustrate the influence of network parameters on the proposed approach. Application to experimental data further demonstrates the validity and robustness of our method.
On Noncontextual, Non-Kolmogorovian Hidden Variable Theories
Feintzeig, Benjamin H.; Fletcher, Samuel C.
2017-01-01
One implication of Bell's theorem is that there cannot in general be hidden variable models for quantum mechanics that both are noncontextual and retain the structure of a classical probability space. Thus, some hidden variable programs aim to retain noncontextuality at the cost of using a generalization of the Kolmogorov probability axioms. We generalize a theorem of Feintzeig (Br J Philos Sci 66(4): 905-927, 2015) to show that such programs are committed to the existence of a finite null cover for some quantum mechanical experiments, i.e., a finite collection of probability zero events whose disjunction exhausts the space of experimental possibilities.
Backward causation, hidden variables and the meaning of completeness
Indian Academy of Sciences (India)
Huw Price
2001-02-01
Bell’s theorem requires the assumption that hidden variables are independent of future measurement settings. This independence assumption rests on surprisingly shaky ground. In particular, it is puzzlingly time-asymmetric. The paper begins with a summary of the case for considering hidden variable models which, in abandoning this independence assumption, allow a degree of ‘backward causation’. The remainder of the paper clariﬁes the physical signiﬁcance of such models, in relation to the issue as to whether quantum mechanics provides a complete description of physical reality.
On Noncontextual, Non-Kolmogorovian Hidden Variable Theories
Feintzeig, Benjamin H.; Fletcher, Samuel C.
2017-02-01
One implication of Bell's theorem is that there cannot in general be hidden variable models for quantum mechanics that both are noncontextual and retain the structure of a classical probability space. Thus, some hidden variable programs aim to retain noncontextuality at the cost of using a generalization of the Kolmogorov probability axioms. We generalize a theorem of Feintzeig (Br J Philos Sci 66(4): 905-927, 2015) to show that such programs are committed to the existence of a finite null cover for some quantum mechanical experiments, i.e., a finite collection of probability zero events whose disjunction exhausts the space of experimental possibilities.
A Sequence of Relaxations Constraining Hidden Variable Models
Steeg, Greg Ver
2011-01-01
Many widely studied graphical models with latent variables lead to nontrivial constraints on the distribution of the observed variables. Inspired by the Bell inequalities in quantum mechanics, we refer to any linear inequality whose violation rules out some latent variable model as a "hidden variable test" for that model. Our main contribution is to introduce a sequence of relaxations which provides progressively tighter hidden variable tests. We demonstrate applicability to mixtures of sequences of i.i.d. variables, Bell inequalities, and homophily models in social networks. For the last, we demonstrate that our method provides a test that is able to rule out latent homophily as the sole explanation for correlations on a real social network that are known to be due to influence.
Optical Test of Local Hidden-Variable Model
Institute of Scientific and Technical Information of China (English)
WU XiaoHua; ZONG HongShi; PANG HouRong
2001-01-01
An inequality is deduced from local realism and a supplementary assumption. This inequality defines an experiment that can be actually performed with the present technology to test local hidden-variable models, and it is violated by quantum mechanics with a factor 1.92, while it can be simplified into a form where just two measurements are required.``
Local clustering in scale-free networks with hidden variables
van der Hofstad, Remco; Janssen, A. J. E. M.; van Leeuwaarden, Johan S. H.; Stegehuis, Clara
2017-02-01
We investigate the presence of triangles in a class of correlated random graphs in which hidden variables determine the pairwise connections between vertices. The class rules out self-loops and multiple edges. We focus on the regime where the hidden variables follow a power law with exponent τ ∈(2 ,3 ) , so that the degrees have infinite variance. The natural cutoff hc characterizes the largest degrees in the hidden variable models, and a structural cutoff hs introduces negative degree correlations (disassortative mixing) due to the infinite-variance degrees. We show that local clustering decreases with the hidden variable (or degree). We also determine how the average clustering coefficient C scales with the network size N , as a function of hs and hc. For scale-free networks with exponent 2 universality class at hand. We characterize the extremely slow decay of C when τ ≈2 and show that for τ =2.1 , say, clustering starts to vanish only for networks as large as N =109 .
On local-hidden-variable no-go theorems
Methot, A. A.
2006-06-01
The strongest attack against quantum mechanics came in 1935 in the form of a paper by Einstein, Podolsky, and Rosen. It was argued that the theory of quantum mechanics could not be called a complete theory of Nature, for every element of reality is not represented in the formalism as such. The authors then put forth a proposition: we must search for a theory where, upon knowing everything about the system, including possible hidden variables, one could make precise predictions concerning elements of reality. This project was ultimately doomed in 1964 with the work of Bell, who showed that the most general local hidden variable theory could not reproduce correlations that arise in quantum mechanics. There exist mainly three forms of no-go theorems for local hidden variable theories. Although almost every physicist knows the consequences of these no-go theorems, not every physicist is aware of the distinctions between the three or even their exact definitions. Thus, we will discuss here the three principal forms of no-go theorems for local hidden variable theories of Nature. We will define Bell theorems, Bell theorems without inequalities, and pseudo-telepathy. A discussion of the similarities and differences will follow.
Critical scaling in hidden state inference for linear Langevin dynamics
Bravi, Barbara; Sollich, Peter
2016-01-01
We consider the problem of inferring the dynamics of unknown (i.e. hidden) nodes from a set of observed trajectories and we study analytically the average prediction error given by the Extended Plefka Expansion applied to it, as presented in [1]. We focus on a stochastic linear dynamics of continuous degrees of freedom interacting via random Gaussian couplings in the infinite network size limit. The expected error on the hidden time courses can be found as the equal-time hidden-to-hidden cova...
Consistent histories, quantum truth functionals, and hidden variables
Griffiths, Robert B.
2000-01-01
A central principle of consistent histories quantum theory, the requirement that quantum descriptions be based upon a single framework (or family), is employed to show that there is no conflict between consistent histories and a no-hidden-variables theorem of Bell, and Kochen and Specker, contrary to a recent claim by Bassi and Ghirardi. The argument makes use of `truth functionals' defined on a Boolean algebra of classical or quantum properties.
Consistent histories, quantum truth functionals, and hidden variables
Griffiths, R B
1999-01-01
A central principle of consistent histories quantum theory, the requirement that quantum descriptions be based upon a single framework (or family), is employed to show that there is no conflict between consistent histories and a no-hidden-variables theorem of Bell, and Kochen and Specker, contrary to a recent claim by Bassi and Ghirardi. The argument makes use of ``truth functionals'' defined on a Boolean algebra of classical or quantum properties.
Hidden blazars and emission line variability of high redshift quasars
Directory of Open Access Journals (Sweden)
Feng Ma
2001-01-01
Full Text Available We have carried out a survey to search for hidden blazars in a sample of z 2 radio{loud quasars. The idea is based on our prediction that we should be able to see large C IV line variability not associated with observed continuum variations or most other emission lines in every radio{loud quasar. Here we report the initial results including the discovery of large C IV line variations in two quasars.
On local-hidden-variable no-go theorems
Méthot, A A
2005-01-01
The strongest attack against quantum mechanics came in 1935 in the form of a paper by Einstein, Podolsky and Rosen. It was argued that the theory of quantum mechanics could not be called a complete theory of Nature, for every element of reality is not represented in the formalism as such. The authors then put forth a proposition: we must search for a theory where, upon knowing everything about the system, including possible hidden variables, one could make precise predictions concerning elements of reality. This project was ultimatly doomed in 1964 with the work of Bell Bell, who showed that the most general local hidden variable theory could not reproduce correlations that arise in quantum mechanics. There exist mainly three forms of no-go theorems for local hidden variable theories. Although almost every physicist knows the consequences of these no-go theorems, not every physicist is aware of the distinctions between the three or even their exact definitions. Thus we will discuss here the three principal fo...
Hidden variable models for quantum mechanics can have local parts
Larsson, Jan-Ake
2009-01-01
We present an explicit nonlocal nonsignaling model which has a nontrivial local part and is compatible with quantum mechanics. This model constitutes a counterexample to Colbeck and Renner's statement [Phys. Rev. Lett. 101, 050403 (2008)] that "any hidden variable model can only be compatible with quantum mechanics if its local part is trivial". Furthermore, we examine Colbeck and Renner's definition of "local part" and find that, in the case of models reproducing the quantum predictions for the singlet state, it is a restriction equivalent to the conjunction of nonsignaling and trivial local part.
Algorithmic information theory and the hidden variable question
Fuchs, Christopher
1992-01-01
The admissibility of certain nonlocal hidden-variable theories are explained via information theory. Consider a pair of Stern-Gerlach devices with fixed nonparallel orientations that periodically perform spin measurements on identically prepared pairs of electrons in the singlet spin state. Suppose the outcomes are recorded as binary strings l and r (with l sub n and r sub n denoting their n-length prefixes). The hidden-variable theories considered here require that there exists a recursive function which may be used to transform l sub n into r sub n for any n. This note demonstrates that such a theory cannot reproduce all the statistical predictions of quantum mechanics. Specifically, consider an ensemble of outcome pairs (l,r). From the associated probability measure, the Shannon entropies H sub n and H bar sub n for strings l sub n and pairs (l sub n, r sub n) may be formed. It is shown that such a theory requires that the absolute value of H bar sub n - H sub n be bounded - contrasting the quantum mechanical prediction that it grow with n.
Hidden Web Data Extraction Using Dynamic Rule Generation
Directory of Open Access Journals (Sweden)
Anuradha
2011-08-01
Full Text Available World Wide Web is a global information medium of interlinked hypertext documents accessed via computers connected to the internet. Most of the users rely on traditional search engines to search theinformation on the web. These search engines deal with the Surface Web which is a set of Web pages directly accessible through hyperlinks and ignores a large part of the Web called Hidden Web which is hidden to present-day search engines. It lies behind search forms and this part of the web containing an almost endless amount of sources providing high quality information stored in specialized databases can be found in the depths of the WWW. A large amount of this Hidden web is structured i.e Hidden websites contain the information in the form of lists and tables. However visiting dozens of these sites and analyzing the results is very much time consuming task for user. Hence, it is desirable to build a prototype which will minimize user’s effort and give him high quality information in integrated form. This paper proposes a novel method that extracts the data records from the lists and tables of various hidden web sites of same domain using dynamic rule generation and forms a repository which is used for later searching. By searching the data from this repository, user will find the desired data at one place. It reduces the user’s effort to look at various result pages of different hidden websites.
Dynamically Generated Open and Hidden Charm Meson Systems
Gamermann, D; Strottman, D D; Vacas, M J V
2006-01-01
The lowest order chiral Lagrangian successfully applied to study the interaction of the SU(3) octet of pseudo-scalar mesons is generalized to include all mesons from the SU(4) 15-plet of pseudo-scalar mesons. Exchanges of heavy vector mesons, which are indirectly taken into account via this approach, are suppressed. Unitarization in coupled channels leads to dynamical generation of resonances in the open and hidden charm sectors. In particular, for reasonable values of the input, a new narrow scalar resonance in the hidden charm sector appears with a mass of 3.7 GeV.
Perpetual points and hidden attractors in dynamical systems
Dudkowski, Dawid; Prasad, Awadhesh; Kapitaniak, Tomasz
2015-10-01
We discuss the use of perpetual points for tracing the hidden and the rare attractors of dynamical systems. The analysis of perpetual points and their co-existence due to the parameters values is presented and the impact of these points on the behavior of the systems is shown. The results are obtained for single as well as coupled externally excited van der Pol-Duffing oscillators. The presented results can be generalized to other systems having different dynamics.
Hidden variable problem for a family of continuously many spin 1 measurements
Kurzynski, Pawel; Soeda, Akihito; Bzdega, Bartlomiej; Kaszlikowski, Dagomir
2012-01-01
We study a continuous set of spin 1 measurements and show that for a special family of measurements parametrized by a single variable $\\theta$ the possibility of hidden-variable description is a discontinuous property.
Perpetual points and hidden attractors in dynamical systems
Energy Technology Data Exchange (ETDEWEB)
Dudkowski, Dawid, E-mail: dawid.dudkowski@p.lodz.pl [Division of Dynamics, Technical University of Lodz, Stefanowskiego 1/15, 90-924 Lodz (Poland); Prasad, Awadhesh [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Kapitaniak, Tomasz [Division of Dynamics, Technical University of Lodz, Stefanowskiego 1/15, 90-924 Lodz (Poland)
2015-10-23
We discuss the use of perpetual points for tracing the hidden and the rare attractors of dynamical systems. The analysis of perpetual points and their co-existence due to the parameters values is presented and the impact of these points on the behavior of the systems is shown. The results are obtained for single as well as coupled externally excited van der Pol–Duffing oscillators. The presented results can be generalized to other systems having different dynamics. - Highlights: • Computation of perpetual points in forced nonlinear dynamical systems. • Locating the hidden and rare attractors using perpetual points. • Analysis of states and different types of synchronization in coupled systems. • Understanding the complexity in coupled and uncoupled forced van der Pol–Duffing oscillator.
Hidden Symmetry of a Fluid Dynamical Model
Neves, C
2001-01-01
A connection between solutions of the relativistic d-brane system in (d+1) dimensions with the solutions of a Galileo invariant fluid in d-dimensions is by now well established. However, the physical nature of the light-cone gauge description of a relativistic membrane changes after the reduction to the fluid dynamical model since the gauge symmetry is lost. In this work we argue that the original gauge symmetry present in a relativistic d-brane system can be recovered after the reduction process to a d-dimensional fluid model. To this end we propose, without introducing Wess-Zumino fields, a gauge invariant theory of isentropic fluid dynamics and show that this symmetry corresponds to the invariance under local translation of the velocity potential in the fluid dynamics picture. We show that different but equivalent choices of the sympletic sector lead to distinct representations of the embedded gauge algebra.
Dynamically generated open and hidden charm mesons
Gamermann, D; Strottman, D; Vacas, M J Vicente
2007-01-01
In this presentation I explain our framework for dynamically generating resonances from the meson meson interaction. Our model generates many poles in the T-matrix which are associated with known states, while at the same time new states are predicted.
Hidden-variable models for the spin singlet: I. Non-local theories reproducing quantum mechanics
Di Lorenzo, Antonio
2011-01-01
A non-local hidden variable model reproducing the quantum mechanical probabilities for a spin singlet is presented. The non-locality is concentrated in the distribution of the hidden variables. The model otherwise satisfies both the hypothesis of outcome independence, made in the derivation of Bell inequality, and of compliance with Malus's law, made in the derivation of Leggett inequality. It is shown through the prescription of a protocol that the non-locality can be exploited to send information instantaneously provided that the hidden variables can be measured, even though they cannot be controlled.
A framework for dynamic indexing from hidden web
Directory of Open Access Journals (Sweden)
Hasan Mahmud
2011-09-01
Full Text Available The proliferation of dynamic websites operating on databases requires generating web pages on-the-fly which is too sophisticated for most of the search engines to index. In an attempt to crawl the contents of dynamic web pages, weve tried to come up with a simple approach to index these huge amounts of dynamic contents hidden behind the search forms. Our key contribution in this paper is the design and implementation of a simple framework to index the dynamic web pages and the use of Hadoop MapReduce framework to update and maintain the index. In our approach, from an initial URL, our crawler downloads both the static and dynamic web pages, detects form interfaces, adaptively selects keywords to generate most promising search results, automatically fill-up search form interfaces, submits the dynamic URL and processes the result until some conditions are satisfied.
Revealing hidden dynamics within living soft matter.
Ott, Dino; Bendix, Poul M; Oddershede, Lene B
2013-10-22
In the study of living soft matter, we often seek to understand the mechanisms underlying the motion of a single molecule, an organelle, or some other tracer. The experimentally observed signature of the tracer is masked by its thermal fluctuations, inherent drift of the system, and instrument noise. In addition, the timing or length scales of the events of interest are often unknown. In the current issue of ACS Nano, Chen et al. present a general method for extracting the underlying dynamics from time series. Here, we provide an easily accessible introduction to the method, put it into perspective with the field, and exemplify how it can be used to answer important out-standing questions within soft matter and living systems.
Inferring hidden states in Langevin dynamics on large networks: Average case performance
Bravi, B.; Opper, M.; Sollich, P.
2017-01-01
We present average performance results for dynamical inference problems in large networks, where a set of nodes is hidden while the time trajectories of the others are observed. Examples of this scenario can occur in signal transduction and gene regulation networks. We focus on the linear stochastic dynamics of continuous variables interacting via random Gaussian couplings of generic symmetry. We analyze the inference error, given by the variance of the posterior distribution over hidden paths, in the thermodynamic limit and as a function of the system parameters and the ratio α between the number of hidden and observed nodes. By applying Kalman filter recursions we find that the posterior dynamics is governed by an "effective" drift that incorporates the effect of the observations. We present two approaches for characterizing the posterior variance that allow us to tackle, respectively, equilibrium and nonequilibrium dynamics. The first appeals to Random Matrix Theory and reveals average spectral properties of the inference error and typical posterior relaxation times; the second is based on dynamical functionals and yields the inference error as the solution of an algebraic equation.
Diboson Resonance as a Portal to Hidden Strong Dynamics
Chiang, Cheng-Wei; Harigaya, Keisuke; Ibe, Masahiro; Yanagida, Tsutomu T
2015-01-01
We propose a new explanation for excess events observed in the search for a high-mass resonance decaying into dibosons by the ATLAS experiment. The resonance is identified as a composite spin-$0$ particle that couples to the Standard Model gauge bosons via dimension-5 operators. The excess events can be explained if the dimension-5 operators are suppressed by a mass scale of ${\\cal O}(1$--$10$) TeV. We also construct a model of hidden strong gauge dynamics which realizes the spin-$0$ particle as its lightest composite state, with appropriate couplings to Standard Model gauge bosons.
Scale-Free Networks Hidden in Chaotic Dynamical Systems
Iba, Takashi
2010-01-01
In this paper, we show our discovery that state-transition networks in several chaotic dynamical systems are "scale-free networks," with a technique to understand a dynamical system as a whole, which we call the analysis for "Discretized-State Transition" (DST) networks; This scale-free nature is found universally in the logistic map, the sine map, the cubic map, the general symmetric map, the sine-circle map, the Gaussian map, and the delayed logistic map. Our findings prove that there is a hidden order in chaos, which has not detected yet. Furthermore, we anticipate that our study opens up a new way to a "network analysis approach to dynamical systems" for understanding complex phenomena.
On-line Fault Diagnosis in Industrial Processes Using Variable Moving Window and Hidden Markov Model
Institute of Scientific and Technical Information of China (English)
周韶园; 谢磊; 王树青
2005-01-01
An integrated framework is presented to represent and classify process data for on-line identifying abnormal operating conditions. It is based on pattern recognition principles and consists of a feature extraction step, by which wavelet transform and principal component analysis are used to capture the inherent characteristics from process measurements, followed by a similarity assessment step using hidden Markov model (HMM) for pattern comparison. In most previous cases, a fixed-length moving window was employed to track dynamic data, and often failed to capture enough information for each fault and sometimes even deteriorated the diagnostic performance. A variable moving window, the length of which is modified with time, is introduced in this paper and case studies on the Tennessee Eastman process illustrate the potential of the proposed method.
HIDDEN WEB EXTRACTOR DYNAMIC WAY TO UNCOVER THE DEEP WEB
DR. ANURADHA; BABITA AHUJA
2012-01-01
In this era of digital tsunami of information on the web, everyone is completely dependent on the WWW for information retrieval. This has posed a challenging problem in extracting relevant data. Traditional web crawlers focus only on the surface web while the deep web keeps expanding behind the scene. The web databases are hidden behind the query interfaces. In this paper, we propose a Hidden Web Extractor (HWE) that can automatically discover and download data from the Hidden Web databases. ...
A Proposal for Testing Local Realism Without Using Assumptions Related to Hidden Variable States
Ryff, Luiz Carlos
1996-01-01
A feasible experiment is discussed which allows us to prove a Bell's theorem for two particles without using an inequality. The experiment could be used to test local realism against quantum mechanics without the introduction of additional assumptions related to hidden variables states. Only assumptions based on direct experimental observation are needed.
Algorithmic Construction of Local Hidden Variable Models for Entangled Quantum States
Hirsch, Flavien; Quintino, Marco Túlio; Vértesi, Tamás; Pusey, Matthew F.; Brunner, Nicolas
2016-11-01
Constructing local hidden variable (LHV) models for entangled quantum states is a fundamental problem, with implications for the foundations of quantum theory and for quantum information processing. It is, however, a challenging problem, as the model should reproduce quantum predictions for all possible local measurements. Here we present a simple method for building LHV models, applicable to any entangled state and considering continuous sets of measurements. This leads to a sequence of tests which, in the limit, fully captures the set of quantum states admitting a LHV model. Similar methods are developed for local hidden state models. We illustrate the practical relevance of these methods with several examples.
Algorithmic Construction of Local Hidden Variable Models for Entangled Quantum States.
Hirsch, Flavien; Quintino, Marco Túlio; Vértesi, Tamás; Pusey, Matthew F; Brunner, Nicolas
2016-11-04
Constructing local hidden variable (LHV) models for entangled quantum states is a fundamental problem, with implications for the foundations of quantum theory and for quantum information processing. It is, however, a challenging problem, as the model should reproduce quantum predictions for all possible local measurements. Here we present a simple method for building LHV models, applicable to any entangled state and considering continuous sets of measurements. This leads to a sequence of tests which, in the limit, fully captures the set of quantum states admitting a LHV model. Similar methods are developed for local hidden state models. We illustrate the practical relevance of these methods with several examples.
HIDDEN WEB EXTRACTOR DYNAMIC WAY TO UNCOVER THE DEEP WEB
Directory of Open Access Journals (Sweden)
DR. ANURADHA
2012-06-01
Full Text Available In this era of digital tsunami of information on the web, everyone is completely dependent on the WWW for information retrieval. This has posed a challenging problem in extracting relevant data. Traditional web crawlers focus only on the surface web while the deep web keeps expanding behind the scene. The web databases are hidden behind the query interfaces. In this paper, we propose a Hidden Web Extractor (HWE that can automatically discover and download data from the Hidden Web databases. Since the only “entry point” to a Hidden Web site is a query interface, the main challenge that a Hidden WebExtractor has to face is how to automatically generate meaningful queries for the unlimited number of website pages.
Bianchi Cosmologies New Variables and a Hidden Supersymmetry
Obregón, O; Ryan, M P; Obregon, Octavio; Pullin, Jorge; Ryan, Michael P.
1993-01-01
We find a supersymmetrization of the Bianchi IX cosmology in terms of Ashtekar's new variables. This provides a framework for connecting the recent results of Graham and those of Ryan and Moncrief for quantum states of this model. These states are also related with the states obtained particularizing supergravity for a minisuperspace. Implications for the general theory are also briefly discussed.
The incompatibility between local hidden variable theories and the fundamental conservation laws
Indian Academy of Sciences (India)
C S Unnikrishnan
2005-09-01
I discuss in detail the result that the Bell's inequalities derived in the context of local hidden variable theories for discrete quantized observables can be satisfied only if a fundamental conservation law is violated on the average. This result shows that such theories are physically nonviable, and makes the demarcating criteria of the Bell's inequalities redundant. I show that a unique correlation function can be derived from the validity of the conservation law alone and this coincides with the quantum mechanical correlation function. Thus, any theory with a different correlation function, like any local hidden variable theory, is incompatible with the fundamental conservation laws and space-time symmetries. The results are discussed in the context of two-particle singlet and triplet states, GHZ states, and two-particle double slit interferometry. Some observations on quantum entropy, entanglement, and nonlocality are also discussed.
Quantum Computing and Hidden Variables II: The Complexity of Sampling Histories
Aaronson, S
2004-01-01
This paper shows that, if we could examine the entire history of a hidden variable, then we could efficiently solve problems that are believed to be intractable even for quantum computers. In particular, under any hidden-variable theory satisfying a reasonable axiom called "indifference to the identity," we could solve the Graph Isomorphism and Approximate Shortest Vector problems in polynomial time, as well as an oracle problem that is known to require quantum exponential time. We could also search an N-item database using O(N^{1/3}) queries, as opposed to O(N^{1/2}) queries with Grover's search algorithm. On the other hand, the N^{1/3} bound is optimal, meaning that we could probably not solve NP-complete problems in polynomial time. We thus obtain the first good example of a model of computation that appears slightly more powerful than the quantum computing model.
Post-relativistic gravity a hidden variable theory for general relativity
Schmelzer, I
1996-01-01
Post-relativistic gravity is a hidden variable theory for general relativity. It introduces the pre-relativistic notions absolute space, absolute time, and ether as hidden variables into general relativity. Evolution is defined by the equations of general relativity and the harmonic coordinate condition interpreted as a physical equation. There are minor differences in predictions compared with general relativity (i.e. trivial topology of the universe is predicted). The unobservable absolute time is designed to solve the problem of time in quantization of general relativity. Background space and time define a Newtonian frame for the quantization of the gravitational field. By the way, a lot of other conceptual problems of quantization will be solved (i.e. no constraints, no topological foam, no black hole and bib bang singularities, natural vacuum definition for quantum fields on classical background).
Recovering hidden dynamical modes from the generalized Langevin equation
Kawai, Shinnosuke; Miyazaki, Yusuke
2016-09-01
In studying large molecular systems, insights can better be extracted by selecting a limited number of physical quantities for analysis rather than treating every atomic coordinate in detail. Some information may, however, be lost by projecting the total system onto a small number of coordinates. For such problems, the generalized Langevin equation (GLE) is shown to provide a useful framework to examine the interaction between the observed variables and their environment. Starting with the GLE obtained from the time series of the observed quantity, we perform a transformation to introduce a set of variables that describe dynamical modes existing in the environment. The introduced variables are shown to effectively recover the essential information of the total system that appeared to be lost by the projection.
Energy Technology Data Exchange (ETDEWEB)
Ghil, M. [Univ. of California, Los Angeles, CA (United States); Kravtsov, S. [Univ. of Wisconsin, Madison, WI (United States); Robertson, A. W. [IRI, Palisades, NY (United States); Smyth, P. [Univ. of California, Irvine, CA (United States)
2008-10-14
This project was a continuation of previous work under DOE CCPP funding, in which we had developed a twin approach of probabilistic network (PN) models (sometimes called dynamic Bayesian networks) and intermediate-complexity coupled ocean-atmosphere models (ICMs) to identify the predictable modes of climate variability and to investigate their impacts on the regional scale. We had developed a family of PNs (similar to Hidden Markov Models) to simulate historical records of daily rainfall, and used them to downscale GCM seasonal predictions. Using an idealized atmospheric model, we had established a novel mechanism through which ocean-induced sea-surface temperature (SST) anomalies might influence large-scale atmospheric circulation patterns on interannual and longer time scales; we had found similar patterns in a hybrid coupled ocean-atmosphere-sea-ice model. The goal of the this continuation project was to build on these ICM results and PN model development to address prediction of rainfall and temperature statistics at the local scale, associated with global climate variability and change, and to investigate the impact of the latter on coupled ocean-atmosphere modes. Our main results from the grant consist of extensive further development of the hidden Markov models for rainfall simulation and downscaling together with the development of associated software; new intermediate coupled models; a new methodology of inverse modeling for linking ICMs with observations and GCM results; and, observational studies of decadal and multi-decadal natural climate results, informed by ICM results.
La Cour, Brian R.
2017-07-01
An experiment has recently been performed to demonstrate quantum nonlocality by establishing contextuality in one of a pair of photons encoding four qubits; however, low detection efficiencies and use of the fair-sampling hypothesis leave these results open to possible criticism due to the detection loophole. In this Letter, a physically motivated local hidden-variable model is considered as a possible mechanism for explaining the experimentally observed results. The model, though not intrinsically contextual, acquires this quality upon post-selection of coincident detections.
Quach, Minh; Brunel, Nicolas; d'Alché-Buc, Florence
2007-12-01
Statistical inference of biological networks such as gene regulatory networks, signaling pathways and metabolic networks can contribute to build a picture of complex interactions that take place in the cell. However, biological systems considered as dynamical, non-linear and generally partially observed processes may be difficult to estimate even if the structure of interactions is given. Using the same approach as Sitz et al. proposed in another context, we derive non-linear state-space models from ODEs describing biological networks. In this framework, we apply Unscented Kalman Filtering (UKF) to the estimation of both parameters and hidden variables of non-linear state-space models. We instantiate the method on a transcriptional regulatory model based on Hill kinetics and a signaling pathway model based on mass action kinetics. We successfully use synthetic data and experimental data to test our approach. This approach covers a large set of biological networks models and gives rise to simple and fast estimation algorithms. Moreover, the Bayesian tool used here directly provides uncertainty estimates on parameters and hidden states. Let us also emphasize that it can be coupled with structure inference methods used in Graphical Probabilistic Models. Matlab code available on demand.
Time separation as a hidden variable to the Copenhagen school of quantum mechanics
Kim, Y S
2010-01-01
The Bohr radius is a space-like separation between the proton and electron in the hydrogen atom. According to the Copenhagen school of quantum mechanics, the proton is sitting in the absolute Lorentz frame. If this hydrogen atom is observed from a different Lorentz frame, there is a time-like separation linearly mixed with the Bohr radius. Indeed, the time-separation is one of the essential variables in high-energy hadronic physics where the hadron is a bound state of the quarks, while thoroughly hidden in the present form of quantum mechanics. It will be concluded that this variable is hidden in Feynman's rest of the universe. It is noted first that Feynman's Lorentz-invariant differential equation for the bound-state quarks has a set of solutions which describe all essential features of hadronic physics. These solutions explicitly depend on the time separation between the quarks. This set also forms the mathematical basis for two-mode squeezed states in quantum optics, where both photons are observable, but...
Variable Dynamic Testbed Vehicle: Dynamics Analysis
Lee, A. Y.; Le, N. T.; Marriott, A. T.
1997-01-01
The Variable Dynamic Testbed Vehicle (VDTV) concept has been proposed as a tool to evaluate collision avoidance systems and to perform driving-related human factors research. The goal of this study is to analytically investigate to what extent a VDTV with adjustable front and rear anti-roll bar stiffnesses, programmable damping rates, and four-wheel-steering can emulate the lateral dynamics of a broad range of passenger vehicles.
Thron, Christopher
2017-01-01
Since the time of Galileo, the equations of physics have expressed dynamical variables such as particle position or electromagnetic field strength as functions of time. In this paper, we argue that this assumption reflects observational bias, and that there are many good reasons for viewing time also as a dynamical variable. We hypothesize that the spacetime universe is an outcome of a process, rather than a process unfolding in time. This new viewpoint gives rise to a physical interpretation of the wavefunction as a complex vibrational amplitude in a non-spacetime independent variable. It resolves quantum mechanical paradoxes involving wavefunction entanglement, and gives a much simpler solution to the problem of wavefunction collapse than the many-worlds interpretation. The Born rule is also shown to be a natural consequence. We also show that small deviations from conventional quantum probabilities are predicted.
Vakanski, A; Mantegh, I; Irish, A; Janabi-Sharifi, F
2012-08-01
The main objective of this paper is to develop an efficient method for learning and reproduction of complex trajectories for robot programming by demonstration. Encoding of the demonstrated trajectories is performed with hidden Markov model, and generation of a generalized trajectory is achieved by using the concept of key points. Identification of the key points is based on significant changes in position and velocity in the demonstrated trajectories. The resulting sequences of trajectory key points are temporally aligned using the multidimensional dynamic time warping algorithm, and a generalized trajectory is obtained by smoothing spline interpolation of the clustered key points. The principal advantage of our proposed approach is utilization of the trajectory key points from all demonstrations for generation of a generalized trajectory. In addition, variability of the key points' clusters across the demonstrated set is employed for assigning weighting coefficients, resulting in a generalization procedure which accounts for the relevance of reproduction of different parts of the trajectories. The approach is verified experimentally for trajectories with two different levels of complexity.
Chaos Synchronization Using Adaptive Dynamic Neural Network Controller with Variable Learning Rates
Directory of Open Access Journals (Sweden)
Chih-Hong Kao
2011-01-01
Full Text Available This paper addresses the synchronization of chaotic gyros with unknown parameters and external disturbance via an adaptive dynamic neural network control (ADNNC system. The proposed ADNNC system is composed of a neural controller and a smooth compensator. The neural controller uses a dynamic RBF (DRBF network to online approximate an ideal controller. The DRBF network can create new hidden neurons online if the input data falls outside the hidden layer and prune the insignificant hidden neurons online if the hidden neuron is inappropriate. The smooth compensator is designed to compensate for the approximation error between the neural controller and the ideal controller. Moreover, the variable learning rates of the parameter adaptation laws are derived based on a discrete-type Lyapunov function to speed up the convergence rate of the tracking error. Finally, the simulation results which verified the chaotic behavior of two nonlinear identical chaotic gyros can be synchronized using the proposed ADNNC scheme.
Comparison of the Beta and the Hidden Markov Models of Trust in Dynamic Environments
Moe, Marie E. G.; Helvik, Bjarne E.; Knapskog, Svein J.
Computational trust and reputation models are used to aid the decision-making process in complex dynamic environments, where we are unable to obtain perfect information about the interaction partners. In this paper we present a comparison of our proposed hidden Markov trust model to the Beta reputation system. The hidden Markov trust model takes the time between observations into account, it also distinguishes between system states and uses methods previously applied to intrusion detection for the prediction of which state an agent is in. We show that the hidden Markov trust model performs better when it comes to the detection of changes in behavior of agents, due to its larger richness in model features. This means that our trust model may be more realistic in dynamic environments. However, the increased model complexity also leads to bigger challenges in estimating parameter values for the model. We also show that the hidden Markov trust model can be parameterized so that it responds similarly to the Beta reputation system.
Hidden Markov Model of atomic quantum jump dynamics in an optically probed cavity
DEFF Research Database (Denmark)
Gammelmark, S.; Molmer, K.; Alt, W.
2014-01-01
We analyze the quantum jumps of an atom interacting with a cavity field. The strong atom- field interaction makes the cavity transmission depend on the time dependent atomic state, and we present a Hidden Markov Model description of the atomic state dynamics which is conditioned in a Bayesian......, the atomic state is determined in a Bayesian manner from the measurement data, and we present an iterative protocol, which determines both the atomic state and the model parameters. As a new element in the treatment of observed quantum systems, we employ a Bayesian approach that conditions the atomic state...... manner on the detected signal. We suggest that small variations in the observed signal may be due to spatial motion of the atom within the cavity, and we represent the atomic system by a number of hidden states to account for both the small variations and the internal state jump dynamics. In our theory...
Hidden Markov Model of atomic quantum jump dynamics in an optically probed cavity
DEFF Research Database (Denmark)
Gammelmark, S.; Molmer, K.; Alt, W.
2014-01-01
manner on the detected signal. We suggest that small variations in the observed signal may be due to spatial motion of the atom within the cavity, and we represent the atomic system by a number of hidden states to account for both the small variations and the internal state jump dynamics. In our theory......We analyze the quantum jumps of an atom interacting with a cavity field. The strong atom- field interaction makes the cavity transmission depend on the time dependent atomic state, and we present a Hidden Markov Model description of the atomic state dynamics which is conditioned in a Bayesian......, the atomic state is determined in a Bayesian manner from the measurement data, and we present an iterative protocol, which determines both the atomic state and the model parameters. As a new element in the treatment of observed quantum systems, we employ a Bayesian approach that conditions the atomic state...
Unveiling Hidden Dynamics of Hippo Signalling: A Systems Analysis
Directory of Open Access Journals (Sweden)
Sung-Young Shin
2016-08-01
Full Text Available The Hippo signalling pathway has recently emerged as an important regulator of cell apoptosis and proliferation with significant implications in human diseases. In mammals, the pathway contains the core kinases MST1/2, which phosphorylate and activate LATS1/2 kinases. The pro-apoptotic function of the MST/LATS signalling axis was previously linked to the Akt and ERK MAPK pathways, demonstrating that the Hippo pathway does not act alone but crosstalks with other signalling pathways to coordinate network dynamics and cellular outcomes. These crosstalks were characterised by a multitude of complex regulatory mechanisms involving competitive protein-protein interactions and phosphorylation mediated feedback loops. However, how these different mechanisms interplay in different cellular contexts to drive the context-specific network dynamics of Hippo-ERK signalling remains elusive. Using mathematical modelling and computational analysis, we uncovered that the Hippo-ERK network can generate highly diverse dynamical profiles that can be clustered into distinct dose-response patterns. For each pattern, we offered mechanistic explanation that defines when and how the observed phenomenon can arise. We demonstrated that Akt displays opposing, dose-dependent functions towards ERK, which are mediated by the balance between the Raf-1/MST2 protein interaction module and the LATS1 mediated feedback regulation. Moreover, Ras displays a multi-functional role and drives biphasic responses of both MST2 and ERK activities; which are critically governed by the competitive protein interaction between MST2 and Raf-1. Our study represents the first in-depth and systematic analysis of the Hippo-ERK network dynamics and provides a concrete foundation for future studies.
Nonlinear dynamics of hidden modes in a system with internal symmetry
Perchikov, Nathan; Gendelman, O. V.
2016-09-01
We consider a discrete dynamical system with internal degrees of freedom (DOF). Due to the symmetry between the internal DOFs, certain internal modes cannot be excited by external forcing (in a case of linear interactions) and thus are considered "hidden". If such a system is weakly asymmetric, the internal modes remain approximately "hidden" from the external excitation, given that small damping is taken into account. However, already in the case of weak cubic nonlinearity, these hidden modes can be excited, even as the exact symmetry is preserved. This excitation occurs through parametric resonance. Floquet analysis reveals instability patterns for the explored modes. To perform this analysis with the required accuracy, we suggest a special method for obtaining the Fourier series of the unperturbed solution for the nonlinear normal mode. This method does not require explicit integration of the arising quadratures. Instead, it employs expansion of the solution at the stage of the implicit quadrature in terms of Chebyshev polynomials. The emerging implicit equations are solved by using a fixed-point iteration scheme. Poincaré sections help to clarify the correspondence between the loss of stability of the modes and the global structure of the dynamical flow. In particular, the conditions for intensive energy exchange in the system are characterized.
Critical analysis of the empirical tests of local hidden-variable theories
Santos, Emilio
1992-10-01
A local hidden-variable model is exhibited for the experiments by Aspect, Grangier, and Roger [Phys. Rev. Lett. 47, 460 (1981); 49, 91 (1982)] and Aspect, Dalibard, and Roger [Phys. Rev. Lett. 49, 1804 (1982)] measuring polarization correlation of optical-photon pairs. The model agrees with quantum-mechanical predictions for all measurable quantities even with ideal polarizers and detectors, and emphasizes the need of a high degree of directional correlation, besides the correlation of spin (or polarization or other quantities), in any test of locality. It is proved that homogeneous inequalities, involving only coincidence detection rates, cannot discriminate between quantum mechanics and local theories, which invalidates all previously used empirical tests. The role of supplementary assumptions, like the so-called no enhancement, for the derivation of Bell's inequalities is discussed. Finally it is conjectured that quantum mechanics might be compatible with local realism, if we assume that not all self-adjoint operators represent observables and not all density operators represent states.
Energy Technology Data Exchange (ETDEWEB)
Aharonov, Y. [Texas A and M Univ., College Station, TX (United States); South Carolina Univ., Columbia, SC (United States). Dept. of Physics and Astronomy; Tel Aviv Univ. (Israel). School of Physics and Astronomy; Botero, A. [South Carolina Univ., Columbia, SC (United States). Dept. of Physics and Astronomy; Centro Internacional de Fisica, Ciudad Univ., Bogota (Colombia); Scully, M. [Texas A and M Univ., College Station, TX (United States); Max-Planck-Institut fuer Quantenoptik (MPQ), Garching (Germany)
2001-02-01
The folklore notion of the ''Non-Locality of Quantum Mechanics'' is examined from the point of view of hidden-variables theories according to Belinfante's classification in his Survey of Hidden Variables Theories. It is here shown that in the case of EPR, there exist hidden variables theories that successfully reproduce quantum-mechanical predictions, but which are explicitly local. Since such theories do not fall into Belinfante's classification, we propose an expanded classification which includes similar theories, which we term as theories of the ''third'' kind. Causal implications of such theories are explored. (orig.)
Tan, Wei Lun; Yusof, Fadhilah; Yusop, Zulkifli
2017-07-01
This study involves the modelling of a homogeneous hidden Markov model (HMM) on the northeast rainfall monsoon using 40 rainfall stations in Peninsular Malaysia for the period of 1975 to 2008. A six hidden states HMM was selected based on Bayesian information criterion (BIC), and every hidden state has distinct rainfall characteristics. Three of the states were found to correspond by wet conditions; while the remaining three states were found to correspond to dry conditions. The six hidden states were found to correspond with the associated atmospheric composites. The relationships between El Niño-Southern Oscillation (ENSO) and the sea surface temperatures (SST) in the Pacific Ocean are found regarding interannual variability. The wet (dry) states were found to be well correlated with a Niño 3.4 index which was used to characterize the intensity of an ENSO event. This model is able to assess the behaviour of the rainfall characteristics with the large scale atmospheric circulation; the monsoon rainfall is well correlated with the El Niño-Southern Oscillation in Peninsular Malaysia.
Tan, Wei Lun; Yusof, Fadhilah; Yusop, Zulkifli
2016-04-01
This study involves the modelling of a homogeneous hidden Markov model (HMM) on the northeast rainfall monsoon using 40 rainfall stations in Peninsular Malaysia for the period of 1975 to 2008. A six hidden states HMM was selected based on Bayesian information criterion (BIC), and every hidden state has distinct rainfall characteristics. Three of the states were found to correspond by wet conditions; while the remaining three states were found to correspond to dry conditions. The six hidden states were found to correspond with the associated atmospheric composites. The relationships between El Niño-Southern Oscillation (ENSO) and the sea surface temperatures (SST) in the Pacific Ocean are found regarding interannual variability. The wet (dry) states were found to be well correlated with a Niño 3.4 index which was used to characterize the intensity of an ENSO event. This model is able to assess the behaviour of the rainfall characteristics with the large scale atmospheric circulation; the monsoon rainfall is well correlated with the El Niño-Southern Oscillation in Peninsular Malaysia.
Directory of Open Access Journals (Sweden)
V.-T. Pham
2014-11-01
Full Text Available Memristor-based systems and their potential applications, in which memristor is both a nonlinear element and a memory element, have been received significant attention recently. A memristor-based hyperchaotic system with hidden attractor is studied in this paper. The dynamics properties of this hyperchaotic system are discovered through equilibria, Lyapunov exponents, bifurcation diagram, Poincaré map and limit cycles. In addition, its anti-synchronization scheme via adaptive control method is also designed and MATLAB simulations are shown. Finally, an electronic circuit emulating the memristor-based hyperchaotic system has been designed using off-the-shelf components.
Contribution of hidden modes to nonlinear epidemic dynamics in urban human proximity networks
Fujiwara, Naoya; Iwayama, Koji; Aihara, Kazuyuki
2015-01-01
Recently developed techniques to acquire high-quality human mobility data allow large-scale simulations of the spread of infectious diseases with high spatial and temporal resolution.Analysis of such data has revealed the oversimplification of existing theoretical frameworks to infer the final epidemic size or influential nodes from the network topology. Here we propose a spectral decomposition-based framework for the quantitative analysis of epidemic processes on realistic networks of human proximity derived from urban mobility data. Common wisdom suggests that modes with larger eigenvalues contribute more to the epidemic dynamics. However, we show that hidden dominant structures, namely modes with smaller eigenvalues but a greater contribution to the epidemic dynamics, exist in the proximity network. This framework provides a basic understanding of the relationship between urban human motion and epidemic dynamics, and will contribute to strategic mitigation policy decisions.
P-wave dynamical generated state and LHCb hidden-charmed pentaquarks
He, Jun
2016-01-01
The P-wave dynamical generated state, as well as S-wave state, from hadron-hadron interactions through exchanging light hadron is investigated explicitly to understand the properties, especially spin-parities, of the hidden-charmed exotic hadrons observed recently at LHCb. In a toy model of two-channel scattering of scalar mesons, it is shown that P-wave state is closer to threshold than S-wave state, and has a relatively small width. An important observation is that the peak of a P-wave state has a height similar to a S-wave state. It suggests P-wave state is even easer to observe in experiment than S-wave state if the width is not very small. The two LHCb hidden-charmed pentaquarks are studied in this scheme. The $P_c(4380)$ and the $P_c(4450)$ can be assigned as $3/2^-$-wave and $5/2^+$-wave states dynamically generated from the $\\bar{D}^*\\Sigma_c$ interaction, respectively. The peak for the $P_c(4380)$ in the $J/\\psi p$ invariant mass spectrum is broader but lower than the peak of the $P_c(4450)$, which i...
Hidden Markov induced Dynamic Bayesian Network for recovering time evolving gene regulatory networks
Zhu, Shijia; Wang, Yadong
2015-12-01
Dynamic Bayesian Networks (DBN) have been widely used to recover gene regulatory relationships from time-series data in computational systems biology. Its standard assumption is ‘stationarity’, and therefore, several research efforts have been recently proposed to relax this restriction. However, those methods suffer from three challenges: long running time, low accuracy and reliance on parameter settings. To address these problems, we propose a novel non-stationary DBN model by extending each hidden node of Hidden Markov Model into a DBN (called HMDBN), which properly handles the underlying time-evolving networks. Correspondingly, an improved structural EM algorithm is proposed to learn the HMDBN. It dramatically reduces searching space, thereby substantially improving computational efficiency. Additionally, we derived a novel generalized Bayesian Information Criterion under the non-stationary assumption (called BWBIC), which can help significantly improve the reconstruction accuracy and largely reduce over-fitting. Moreover, the re-estimation formulas for all parameters of our model are derived, enabling us to avoid reliance on parameter settings. Compared to the state-of-the-art methods, the experimental evaluation of our proposed method on both synthetic and real biological data demonstrates more stably high prediction accuracy and significantly improved computation efficiency, even with no prior knowledge and parameter settings.
Zhu, Shijia; Wang, Yadong
2015-12-18
Dynamic Bayesian Networks (DBN) have been widely used to recover gene regulatory relationships from time-series data in computational systems biology. Its standard assumption is 'stationarity', and therefore, several research efforts have been recently proposed to relax this restriction. However, those methods suffer from three challenges: long running time, low accuracy and reliance on parameter settings. To address these problems, we propose a novel non-stationary DBN model by extending each hidden node of Hidden Markov Model into a DBN (called HMDBN), which properly handles the underlying time-evolving networks. Correspondingly, an improved structural EM algorithm is proposed to learn the HMDBN. It dramatically reduces searching space, thereby substantially improving computational efficiency. Additionally, we derived a novel generalized Bayesian Information Criterion under the non-stationary assumption (called BWBIC), which can help significantly improve the reconstruction accuracy and largely reduce over-fitting. Moreover, the re-estimation formulas for all parameters of our model are derived, enabling us to avoid reliance on parameter settings. Compared to the state-of-the-art methods, the experimental evaluation of our proposed method on both synthetic and real biological data demonstrates more stably high prediction accuracy and significantly improved computation efficiency, even with no prior knowledge and parameter settings.
Directory of Open Access Journals (Sweden)
Tan N Doan
Full Text Available Little is known about the transmission dynamics of Acinetobacter baumannii in hospitals, despite such information being critical for designing effective infection control measures. In the absence of comprehensive epidemiological data, mathematical modelling is an attractive approach to understanding transmission process. The statistical challenge in estimating transmission parameters from infection data arises from the fact that most patients are colonised asymptomatically and therefore the transmission process is not fully observed. Hidden Markov models (HMMs can overcome this problem. We developed a continuous-time structured HMM to characterise the transmission dynamics, and to quantify the relative importance of different acquisition sources of A. baumannii in intensive care units (ICUs in three hospitals in Melbourne, Australia. The hidden states were the total number of patients colonised with A. baumannii (both detected and undetected. The model input was monthly incidence data of the number of detected colonised patients (observations. A Bayesian framework with Markov chain Monte Carlo algorithm was used for parameter estimations. We estimated that 96-98% of acquisition in Hospital 1 and 3 was due to cross-transmission between patients; whereas most colonisation in Hospital 2 was due to other sources (sporadic acquisition. On average, it takes 20 and 31 days for each susceptible individual in Hospital 1 and Hospital 3 to become colonised as a result of cross-transmission, respectively; whereas it takes 17 days to observe one new colonisation from sporadic acquisition in Hospital 2. The basic reproduction ratio (R0 for Hospital 1, 2 and 3 was 1.5, 0.02 and 1.6, respectively. Our study is the first to characterise the transmission dynamics of A. baumannii using mathematical modelling. We showed that HMMs can be applied to sparse hospital infection data to estimate transmission parameters despite unobserved events and imperfect detection of
The detection of hidden visual loss in optic neuropathy: VISTECH test at variable illuminations.
Leys, M J; Candaele, C M; Uvijls, A G; Heintz, B F; De Rouck, A F; Odom, J V
1990-01-01
The sensitivity of the VISTECH chart in the detection of hidden visual loss is debated. We tried to evaluate the diagnostic value of the test by using different illumination levels. Twelve MS-patients with normal acuity but a pathological VEP were examined at 9 different illuminations. We did not identify more abnormalities among patients, using VISTECH test at other illumination levels than the one recommended by the manufacturer.
Dynamic Arm Gesture Recognition Using Spherical Angle Features and Hidden Markov Models
Directory of Open Access Journals (Sweden)
Hyesuk Kim
2015-01-01
Full Text Available We introduce a vision-based arm gesture recognition (AGR system using Kinect. The AGR system learns the discrete Hidden Markov Model (HMM, an effective probabilistic graph model for gesture recognition, from the dynamic pose of the arm joints provided by the Kinect API. Because Kinect’s viewpoint and the subject’s arm length can substantially affect the estimated 3D pose of each joint, it is difficult to recognize gestures reliably with these features. The proposed system performs the feature transformation that changes the 3D Cartesian coordinates of each joint into the 2D spherical angles of the corresponding arm part to obtain view-invariant and more discriminative features. We confirmed high recognition performance of the proposed AGR system through experiments with two different datasets.
A close hidden stellar companion to the SX Phe-type variable star DW Psc
Energy Technology Data Exchange (ETDEWEB)
Qian, S.-B.; Li, L.-J.; Wang, S.-M.; He, J.-J.; Zhou, X.; Jiang, L.-Q., E-mail: qsb@ynao.ac.cn [Yunnan Observatories, Chinese Academy of Sciences (CAS), P.O. Box 110, 650011 Kunming (China)
2015-01-01
DW Psc is a high-amplitude SX Phe-type variable with a period of pulsation of 0.05875 days. Using a few newly determined times of maximum light together with those collected from the literature, the changes in the observed-calculated (O-C) diagram are analyzed. It is discovered that the O-C curve of DW Psc shows a cyclic variation with a period of 6.08 years and a semi-amplitude of 0.0066 days. The periodic variation is analyzed for the light travel time effect, which is due to the presence of a stellar companion (M{sub 2}sini∼0.45(±0.03) M{sub ⊙}). The two-component stars in the binary system are orbiting each other in an eccentric orbit (e ∼ 0.4) at an orbital separation of about 2.7(±0.3) AU. The detection of a close stellar companion to an SX Phe-type star supports the idea that SX Phe-type pulsating stars are blue stragglers that were formed from the merging of close binaries. The stellar companion has played an important role in the merging of the original binary by removing angular momentum from the central binary during early dynamical interaction or/and late dynamical evolution. After the more massive component in DW Psc evolves into a red giant, the cool close companion should help to remove the giant envelope via possible critical Roche-lobe overflow, and the system may be a progenitor of a cataclysmic variable. The detection of a close stellar companion to DW Psc makes it a very interesting system to study in the future.
Turner, Sean; Galelli, Stefano; Wilcox, Karen
2015-04-01
Water reservoir systems are often affected by recurring large-scale ocean-atmospheric anomalies, known as teleconnections, that cause prolonged periods of climatological drought. Accurate forecasts of these events -- at lead times in the order of weeks and months -- may enable reservoir operators to take more effective release decisions to improve the performance of their systems. In practice this might mean a more reliable water supply system, a more profitable hydropower plant or a more sustainable environmental release policy. To this end, climate indices, which represent the oscillation of the ocean-atmospheric system, might be gainfully employed within reservoir operating models that adapt the reservoir operation as a function of the climate condition. This study develops a Stochastic Dynamic Programming (SDP) approach that can incorporate climate indices using a Hidden Markov Model. The model simulates the climatic regime as a hidden state following a Markov chain, with the state transitions driven by variation in climatic indices, such as the Southern Oscillation Index. Time series analysis of recorded streamflow data reveals the parameters of separate autoregressive models that describe the inflow to the reservoir under three representative climate states ("normal", "wet", "dry"). These models then define inflow transition probabilities for use in a classic SDP approach. The key advantage of the Hidden Markov Model is that it allows conditioning the operating policy not only on the reservoir storage and the antecedent inflow, but also on the climate condition, thus potentially allowing adaptability to a broader range of climate conditions. In practice, the reservoir operator would effect a water release tailored to a specific climate state based on available teleconnection data and forecasts. The approach is demonstrated on the operation of a realistic, stylised water reservoir with carry-over capacity in South-East Australia. Here teleconnections relating
Kogan, J A; Margoliash, D
1998-04-01
The performance of two techniques is compared for automated recognition of bird song units from continuous recordings. The advantages and limitations of dynamic time warping (DTW) and hidden Markov models (HMMs) are evaluated on a large database of male songs of zebra finches (Taeniopygia guttata) and indigo buntings (Passerina cyanea), which have different types of vocalizations and have been recorded under different laboratory conditions. Depending on the quality of recordings and complexity of song, the DTW-based technique gives excellent to satisfactory performance. Under challenging conditions such as noisy recordings or presence of confusing short-duration calls, good performance of the DTW-based technique requires careful selection of templates that may demand expert knowledge. Because HMMs are trained, equivalent or even better performance of HMMs can be achieved based only on segmentation and labeling of constituent vocalizations, albeit with many more training examples than DTW templates. One weakness in HMM performance is the misclassification of short-duration vocalizations or song units with more variable structure (e.g., some calls, and syllables of plastic songs). To address these and other limitations, new approaches for analyzing bird vocalizations are discussed.
Strohmaier, Markus; Walk, Simon; Pöschko, Jan; Lamprecht, Daniel; Tudorache, Tania; Nyulas, Csongor; Musen, Mark A; Noy, Natalya F
2013-05-01
Traditionally, evaluation methods in the field of semantic technologies have focused on the end result of ontology engineering efforts, mainly, on evaluating ontologies and their corresponding qualities and characteristics. This focus has led to the development of a whole arsenal of ontology-evaluation techniques that investigate the quality of ontologies as a product. In this paper, we aim to shed light on the process of ontology engineering construction by introducing and applying a set of measures to analyze hidden social dynamics. We argue that especially for ontologies which are constructed collaboratively, understanding the social processes that have led to its construction is critical not only in understanding but consequently also in evaluating the ontology. With the work presented in this paper, we aim to expose the texture of collaborative ontology engineering processes that is otherwise left invisible. Using historical change-log data, we unveil qualitative differences and commonalities between different collaborative ontology engineering projects. Explaining and understanding these differences will help us to better comprehend the role and importance of social factors in collaborative ontology engineering projects. We hope that our analysis will spur a new line of evaluation techniques that view ontologies not as the static result of deliberations among domain experts, but as a dynamic, collaborative and iterative process that needs to be understood, evaluated and managed in itself. We believe that advances in this direction would help our community to expand the existing arsenal of ontology evaluation techniques towards more holistic approaches.
Population dynamics in variable environments
Tuljapurkar, Shripad
1990-01-01
Demography relates observable facts about individuals to the dynamics of populations. If the dynamics are linear and do not change over time, the classical theory of Lotka (1907) and Leslie (1945) is the central tool of demography. This book addresses the situation when the assumption of constancy is dropped. In many practical situations, a population will display unpredictable variation over time in its vital rates, which must then be described in statistical terms. Most of this book is concerned with the theory of populations which are subject to random temporal changes in their vital rates, although other kinds of variation (e. g. , cyclical) are also dealt with. The central questions are: how does temporal variation work its way into a population's future, and how does it affect our interpretation of a population's past. The results here are directed at demographers of humans and at popula tion biologists. The uneven mathematical level is dictated by the material, but the book should be accessible to re...
Learning dynamic Bayesian networks with mixed variables
DEFF Research Database (Denmark)
Bøttcher, Susanne Gammelgaard
This paper considers dynamic Bayesian networks for discrete and continuous variables. We only treat the case, where the distribution of the variables is conditional Gaussian. We show how to learn the parameters and structure of a dynamic Bayesian network and also how the Markov order can be learn....... An automated procedure for specifying prior distributions for the parameters in a dynamic Bayesian network is presented. It is a simple extension of the procedure for the ordinary Bayesian networks. Finally the W¨olfer?s sunspot numbers are analyzed....
Dynamics of mechanical systems with variable mass
Belyaev, Alexander
2014-01-01
The book presents up-to-date and unifying formulations for treating dynamics of different types of mechanical systems with variable mass. The starting point is overview of the continuum mechanics relations of balance and jump for open systems from which extended Lagrange and Hamiltonian formulations are derived. Corresponding approaches are stated at the level of analytical mechanics with emphasis on systems with a position-dependent mass and at the level of structural mechanics. Special emphasis is laid upon axially moving structures like belts and chains, and on pipes with an axial flow of fluid. Constitutive relations in the dynamics of systems with variable mass are studied with particular reference to modeling of multi-component mixtures. The dynamics of machines with a variable mass are treated in detail and conservation laws and the stability of motion will be analyzed. Novel finite element formulations for open systems in coupled fluid and structural dynamics are presented.
Yu, Yi-Kuo
2007-02-01
We construct a metric measure among weight matrices that are commonly used in non-interacting statistical physics systems, computational biology problems, as well as in general applications such as hidden Markov models. The metric distance between two weight matrices is obtained via aligning the matrices and thus can be evaluated by dynamic programming. Capable of allowing reverse complements in distance evaluation, this metric accommodates both gapless and gapped alignments between two weight matrices. The distance statistics among random motifs is also studied. We find that the average square distance and its standard error grow with different powers of motif length, and the normalized square distance follows a Gaussian distribution for large motif lengths.
Variability in primary productivity determines metapopulation dynamics.
Fernández, Néstor; Román, Jacinto; Delibes, Miguel
2016-04-13
Temporal variability in primary productivity can change habitat quality for consumer species by affecting the energy levels available as food resources. However, it remains unclear how habitat-quality fluctuations may determine the dynamics of spatially structured populations, where the effects of habitat size, quality and isolation have been customarily assessed assuming static habitats. We present the first empirical evaluation on the effects of stochastic fluctuations in primary productivity--a major outcome of ecosystem functions--on the metapopulation dynamics of a primary consumer. A unique 13-year dataset from an herbivore rodent was used to test the hypothesis that inter-annual variations in primary productivity determine spatiotemporal habitat occupancy patterns and colonization and extinction processes. Inter-annual variability in productivity and in the growing season phenology significantly influenced habitat colonization patterns and occupancy dynamics. These effects lead to changes in connectivity to other potentially occupied habitat patches, which then feed back into occupancy dynamics. According to the results, the dynamics of primary productivity accounted for more than 50% of the variation in occupancy probability, depending on patch size and landscape configuration. Evidence connecting primary productivity dynamics and spatiotemporal population processes has broad implications for metapopulation persistence in fluctuating and changing environments.
Scaringi, S; Middleton, M
2014-01-01
We explore the non-linear, high-frequency, aperiodic variability properties in the three cataclysmic variables MV Lyr, KIC 8751494 and V1504 Cyg observed with Kepler, as well as the X-ray binary Cyg X-1 observed with RXTE. This is done through the use of a high-order Fourier statistic called the bispectrum and its related biphase and bicoherence, as well as the time-skewness statistic. We show how all objects display qualitatively similar biphase trends. In particular all biphase amplitudes are found to be smaller than $\\pi/2$, suggesting that the flux distributions for all sources are positively skewed on all observed timescales, consistent with the log-normal distributions expected from the fluctuating accretion disk model. We also find that for all objects the biphases are positive at frequencies where the corresponding power spectral densities display their high frequency break. This suggests that the noise-like flaring observed is rising more slowly than it is falling, and thus not time-reversible. This ...
DYNAMIC DESIGN OF VARIABLE SPEED PLANAR LINKAGES
Institute of Scientific and Technical Information of China (English)
Yao Yanan; Yan Hongsen; Zou Huijun
2005-01-01
A method for improving dynamic characteristics of planar linkages by actively varying the speed function of the input link is presented. Design criteria and constraints for the dynamic design of variable speed planar linkages are developed. Both analytical and optimization approaches for determining suitable input speed functions to minimize the driving torque, the shaking moment, or both simultaneously of planar linkages, subject to various design requirements and constraints, are derived.Finally, some examples are given to illustrate the design procedure and to verify its feasibility.
Variational Infinite Hidden Conditional Random Fields
Bousmalis, Konstantinos; Zafeiriou, Stefanos; Morency, Louis-Philippe; Pantic, Maja; Ghahramani, Zoubin
2015-01-01
Hidden conditional random fields (HCRFs) are discriminative latent variable models which have been shown to successfully learn the hidden structure of a given classification problem. An Infinite hidden conditional random field is a hidden conditional random field with a countably infinite number of
Liang, Wei-Hong; Xiao, C. W.; Oset, E.
2016-05-01
In this talk we review the results about the interaction of B ¯N , B ¯Δ, B ¯*N and B ¯*Δ states with beauty B = 1, together with their coupled channels, using the extended local hidden gauge approach. The Λb(5912) and Λb(5920) observed in the experiment are dynamically generated from the meson-baryon interaction, and they couple mostly to B ¯*N , which are degenerate with the Weinberg-Tomozawa interaction. In addition, three more states with I = 0 and eight more states with I = 1 are predicted.
Entanglement without hidden nonlocality
Hirsch, Flavien; Túlio Quintino, Marco; Bowles, Joseph; Vértesi, Tamás; Brunner, Nicolas
2016-11-01
We consider Bell tests in which the distant observers can perform local filtering before testing a Bell inequality. Notably, in this setup, certain entangled states admitting a local hidden variable model in the standard Bell scenario can nevertheless violate a Bell inequality after filtering, displaying so-called hidden nonlocality. Here we ask whether all entangled states can violate a Bell inequality after well-chosen local filtering. We answer this question in the negative by showing that there exist entangled states without hidden nonlocality. Specifically, we prove that some two-qubit Werner states still admit a local hidden variable model after any possible local filtering on a single copy of the state.
Variable length Markov chains and dynamical sources
Cénac, Peggy; Paccaut, Frédéric; Pouyanne, Nicolas
2010-01-01
Infinite random sequences of letters can be viewed as stochastic chains or as strings produced by a source, in the sense of information theory. The relationship between Variable Length Markov Chains (VLMC) and probabilistic dynamical sources is studied. We establish a probabilistic frame for context trees and VLMC and we prove that any VLMC is a dynamical source for which we explicitly build the mapping. On two examples, the ``comb'' and the ``bamboo blossom'', we find a necessary and sufficient condition for the existence and the unicity of a stationary probability measure for the VLMC. These two examples are detailed in order to provide the associated Dirichlet series as well as the generating functions of word occurrences.
Dynamic asset allocation and latent variables
DEFF Research Database (Denmark)
Sørensen, Carsten; Trolle, Anders Bjerre
We derive an explicit solution to the portfolio problem of a power utility investorwith preferences for wealth at a ¯nite investment horizon. The investor can investin assets with return dynamics described as part of a general multivariate model.The modeling framework encompasses discrete-time VAR......-models where some ofthe state-variables (e.g. expected excess returns) may not be directly observable.A realistic multivariate model is estimated and applied to analyze the portfolioimplications of investment horizon and return predictability when real interest ratesand expected excess returns on stock...
Synchronized flux limiting for gas dynamics variables
Lohmann, Christoph; Kuzmin, Dmitri
2016-12-01
This work addresses the design of failsafe flux limiters for systems of conserved quantities and derived variables in numerical schemes for the equations of gas dynamics. Building on Zalesak's multidimensional flux-corrected transport (FCT) algorithm, we construct a new positivity-preserving limiter for the density, total energy, and pressure. The bounds for the underlying inequality constraints are designed to enforce local maximum principles in regions of strong density variations and become less restrictive in smooth regions. The proposed approach leads to closed-form expressions for the synchronized correction factors without the need to solve inequality-constrained optimization problems. A numerical study is performed for the compressible Euler equations discretized using a finite element based FCT scheme.
Kuznetsov, N. V.; Leonov, G. A.; Yuldashev, M. V.; Yuldashev, R. V.
2017-10-01
During recent years it has been shown that hidden oscillations, whose basin of attraction does not overlap with small neighborhoods of equilibria, may significantly complicate simulation of dynamical models, lead to unreliable results and wrong conclusions, and cause serious damage in drilling systems, aircrafts control systems, electromechanical systems, and other applications. This article provides a survey of various phase-locked loop based circuits (used in satellite navigation systems, optical, and digital communication), where such difficulties take place in MATLAB and SPICE. Considered examples can be used for testing other phase-locked loop based circuits and simulation tools, and motivate the development and application of rigorous analytical methods for the global analysis of phase-locked loop based circuits.
Eldar, Eran; Morris, Genela; Niv, Yael
2011-09-30
A central goal of neuroscience is to understand how neural dynamics bring about the dynamics of behavior. However, neural and behavioral measures are noisy, requiring averaging over trials and subjects. Unfortunately, averaging can obscure the very dynamics that we are interested in, masking abrupt changes and artificially creating gradual processes. We develop a hidden semi-Markov model for precisely characterizing dynamic processes and their alteration due to experimental manipulations. This method takes advantage of multiple trials and subjects without compromising the information available in individual events within a trial. We apply our model to studying the effects of motivation on response rates, analyzing data from hungry and sated rats trained to press a lever to obtain food rewards on a free-operant schedule. Our method can accurately account for punctate changes in the rate of responding and for sequential dependencies between responses. It is ideal for inferring the statistics of underlying response rates and the probability of switching from one response rate to another. Using the model, we show that hungry rats have more distinct behavioral states that are characterized by high rates of responding and they spend more time in these high-press-rate states. Moreover, hungry rats spend less time in, and have fewer distinct states that are characterized by a lack of responding (Waiting/Eating states). These results demonstrate the utility of our analysis method, and provide a precise quantification of the effects of motivation on response rates.
Smoothing tautologies, hidden dynamics, and sigmoid asymptotics for piecewise smooth systems
Energy Technology Data Exchange (ETDEWEB)
Jeffrey, Mike R., E-mail: mike.jeffrey@bristol.ac.uk [Engineering Mathematics, University of Bristol, Merchant Venturer' s Building, Bristol BS8 1UB (United Kingdom)
2015-10-15
Switches in real systems take many forms, such as impacts, electronic relays, mitosis, and the implementation of decisions or control strategies. To understand what is lost, and what can be retained, when we model a switch as an instantaneous event, requires a consideration of so-called hidden terms. These are asymptotically vanishing outside the switch, but can be encoded in the form of nonlinear switching terms. A general expression for the switch can be developed in the form of a series of sigmoid functions. We review the key steps in extending Filippov's method of sliding modes to such systems. We show how even slight nonlinear effects can hugely alter the behaviour of an electronic control circuit, and lead to “hidden” attractors inside the switching surface.
Climate variability effects on spatial soil moisture dynamics
Teuling, A.J.; Hupet, F.; Uijlenhoet, R.; Troch, P.A.
2007-01-01
We investigate the role of interannual climate variability on spatial soil moisture variability dynamics for a field site in Louvain-la-Neuve, Belgium. Observations were made during 3 years under intermediate (1999), wet (2000), and extremely dry conditions (2003). Soil moisture variability dynamics
Institute of Scientific and Technical Information of China (English)
周韶园; 谢磊; 王树青
2005-01-01
An integrated framework is presented to represent and classify process data for on-line identifying abnormal operating conditions. It is based on pattern recognition principles and consists of a feature extraction step, by which wavelet transform and principal component analysis are used to capture the inherent characteristics from process measurements, followed by a similarity assessment step using hidden Markov model (HMM) for pattern comparison. In most previous cases, a fixed-length moving window was employed to track dynamic data, and often failed to capture enough information for each fault and sometimes even deteriorated the diagnostic performance. A variable moving window, the length of which is modified with time, is introduced in this paper and case studies on the Tennessee Eastman process illustrate the potential of the proposed method.
Dynamical variability in Saturn Equatorial Atmosphere
Sánchez-Lavega, A.; Pérez-Hoyos, S.; Hueso, R.; Rojas, J. F.; French, R. G.; Grupo Ciencias Planetarias Team
2003-05-01
Historical ground-based and recent HST observations show that Saturn's Equatorial Atmosphere is the region where the most intense large-scale dynamical variability took place at cloud level in the planet. Large-scale convective storms (nicknamed the ``Great White Spots") occurred in 1876, 1933 and 1990. The best studied case (the 1990 storm), produced a dramatic change in the cloud aspect in the years following the outburst of September 1990. Subsequently, a new large storm formed in 1994 and from 1996 to 2002 our HST observations showed periods of unusual cloud activity in the southern part of the Equator. This contrast with the aspect observed during the Voyager 1 and 2 encounters in 1980 and 1981 when the Equator was calm, except for some mid-scale plume-like features seen in 1981. Cloud-tracking of the features have revealed a dramatic slow down in the equatorial winds from maximum velocities of ˜ 475 m/s in 1980-1981 to ˜ 275 m/s during 1996-2002, as we have recently reported in Nature, Vol. 423, 623 (2003). We discuss the possibility that seasonal and ring-shadowing effects are involved in generating this activity and variability. Acknowledgements: This work was supported by the Spanish MCYT PNAYA 2000-0932. SPH acknowledges a PhD fellowship from the Spanish MECD and RH a post-doc fellowship from Gobierno Vasco. RGF was supported in part by NASA's Planetary Geology and Geophysics Program NAG5-10197 and STSCI Grant GO-08660.01A.
Modeling anger and aggressive driving behavior in a dynamic choice-latent variable model.
Danaf, Mazen; Abou-Zeid, Maya; Kaysi, Isam
2015-02-01
This paper develops a hybrid choice-latent variable model combined with a Hidden Markov model in order to analyze the causes of aggressive driving and forecast its manifestations accordingly. The model is grounded in the state-trait anger theory; it treats trait driving anger as a latent variable that is expressed as a function of individual characteristics, or as an agent effect, and state anger as a dynamic latent variable that evolves over time and affects driving behavior, and that is expressed as a function of trait anger, frustrating events, and contextual variables (e.g., geometric roadway features, flow conditions, etc.). This model may be used in order to test measures aimed at reducing aggressive driving behavior and improving road safety, and can be incorporated into micro-simulation packages to represent aggressive driving. The paper also presents an application of this model to data obtained from a driving simulator experiment performed at the American University of Beirut. The results derived from this application indicate that state anger at a specific time period is significantly affected by the occurrence of frustrating events, trait anger, and the anger experienced at the previous time period. The proposed model exhibited a better goodness of fit compared to a similar simple joint model where driving behavior and decisions are expressed as a function of the experienced events explicitly and not the dynamic latent variable.
Climate variability effects on spatial soil moisture dynamics
A. J. Teuling; Hupet, F.; R. Uijlenhoet; P. A. Troch
2007-01-01
We investigate the role of interannual climate variability on spatial soil moisture variability dynamics for a field site in Louvain-la-Neuve, Belgium. Observations were made during 3 years under intermediate (1999), wet (2000), and extremely dry conditions (2003). Soil moisture variability dynamics are simulated with a comprehensive model for the period 1989-2003. The results show that climate variability induces non-uniqueness and two distinct hysteresis modes in the yearly relation between...
Directory of Open Access Journals (Sweden)
Panduranga Prashanth
2010-01-01
Full Text Available It is known that a dynamic left ventricular outflow tract (LVOT obstruction exists in patients, following aortic valve replacement (AVR and is usually considered to be benign. We present a patient with dynamic LVOT obstruction following AVR, who developed refractory cardiogenic shock and expired inspite of various treatment strategies. This phenomenon must be diagnosed early and should be considered as a serious and potentially fatal complication following AVR. The possible mechanisms and treatment options are reviewed.
David L. Bellin; Nicholas L. DePace; Robert J. Bulgarelli; Peng Li; Joe Colombo
2015-01-01
Background: A common assumption with autonomic assessment is that one branch opposes the other. With independent measures of parasympathetic (P) and sympathetic (S) activity, based on concurrent time-frequency analysis of respiratory activity and heart rate variability, this assumption has been challenged. Clinical observations of unprovoked P-excess during S-stimulation have been associated with treatable, abnormal responses. Method: Serial autonomic profiling of 12,967 patients was perfo...
Dynamics of bodies with time-variable mass
Cveticanin, Livija
2016-01-01
This book deals with the problem of dynamics of bodies with time-variable mass and moment of inertia. Mass addition and mass separation from the body are treated. Both aspects of mass variation, continual and discontinual, are considered. Dynamic properties of the body are obtained applying principles of classical dynamics and also analytical mechanics. Advantages and disadvantages of both approaches are discussed. Dynamics of constant body is adopted, and the characteristics of the mass variation of the body is included. Special attention is given to the influence of the reactive force and the reactive torque. The vibration of the body with variable mass is presented. One and two degrees of freedom oscillators with variable mass are discussed. Rotors and the Van der Pol oscillator with variable mass are displayed. The chaotic motion of bodies with variable mass is discussed too. To support learning, some solved practical problems are included.
Visible and hidden sectors in a model with Maxwell and Chern-Simons gauge dynamics
Ireson, Edwin; Schaposnik, Fidel A.; Tallarita, Gianni
2016-11-01
We study a U(1) × U(1) gauge theory discussing its vortex solutions and supersymmetric extension. In our set-up, the dynamics of one of two Abelian gauge fields is governed by a Maxwell term, the other by a Chern-Simons term. The two sectors interact via a BF gauge field mixing and a Higgs portal term that connects the two complex scalars. We also consider the supersymmetric version of this system which allows to find for the bosonic sector BPS equations in which an additional real scalar field enters into play. We study numerically the field equations finding vortex solutions with both magnetic flux and electric charge.
Visible and hidden sectors in a model with Maxwell and Chern-Simons gauge dynamics
Ireson, Edwin; Tallarita, Gianni
2016-01-01
We study a $U(1) \\times U(1)$ gauge theory discussing its vortex solutions and supersymmetric extension. In our set-upon the dynamics of one of two Abelian gauge fields is governed by a Maxwell term, the other by a Chern-Simons term. The two sectors via a BF gauge field mixing and a Higgs portal term that connects the two complex scalars. We also consider the supersymmetric version of this system which allows to find for the bosonic sector BPS equations in which an additional real scalar field enters into play. We study numerically the field equations finding vortex solutions with both magnetic flux and electric charge.
Unraveling Hidden Order in the Dynamics of Developed and Emerging Markets
Berman, Yonatan; Shapira, Yoash; Ben-Jacob, Eshel
2014-01-01
The characterization of asset price returns is an important subject in modern finance. Traditionally, the dynamics of stock returns are assumed to lack any temporal order. Here we present an analysis of the autocovariance of stock market indices and unravel temporal order in several major stock markets. We also demonstrate a fundamental difference between developed and emerging markets in the past decade - emerging markets are marked by positive order in contrast to developed markets whose dynamics are marked by weakly negative order. In addition, the reaction to financial crises was found to be reversed among developed and emerging markets, presenting large positive/negative autocovariance spikes following the onset of these crises. Notably, the Chinese market shows neutral or no order while being regarded as an emerging market. These findings show that despite the coupling between international markets and global trading, major differences exist between different markets, and demonstrate that the autocovariance of markets is correlated with their stability, as well as with their state of development. PMID:25383630
Unraveling hidden order in the dynamics of developed and emerging markets.
Berman, Yonatan; Shapira, Yoash; Ben-Jacob, Eshel
2014-01-01
The characterization of asset price returns is an important subject in modern finance. Traditionally, the dynamics of stock returns are assumed to lack any temporal order. Here we present an analysis of the autocovariance of stock market indices and unravel temporal order in several major stock markets. We also demonstrate a fundamental difference between developed and emerging markets in the past decade - emerging markets are marked by positive order in contrast to developed markets whose dynamics are marked by weakly negative order. In addition, the reaction to financial crises was found to be reversed among developed and emerging markets, presenting large positive/negative autocovariance spikes following the onset of these crises. Notably, the Chinese market shows neutral or no order while being regarded as an emerging market. These findings show that despite the coupling between international markets and global trading, major differences exist between different markets, and demonstrate that the autocovariance of markets is correlated with their stability, as well as with their state of development.
Single-molecule dynamics at variable temperatures
Zondervan, Rob
2006-01-01
Single-molecule optics has evolved from a specialized variety of optical spectroscopy at low temperatures into a versatile tool to address questions in physics, chemistry, biology, and materials science. In this thesis, the potential of single-molecule (and ensemble) optical microscopy at variable t
Untangling complex dynamical systems via derivative-variable correlations
Levnaji, Zoran; Pikovsky, Arkady
2014-05-01
Inferring the internal interaction patterns of a complex dynamical system is a challenging problem. Traditional methods often rely on examining the correlations among the dynamical units. However, in systems such as transcription networks, one unit's variable is also correlated with the rate of change of another unit's variable. Inspired by this, we introduce the concept of derivative-variable correlation, and use it to design a new method of reconstructing complex systems (networks) from dynamical time series. Using a tunable observable as a parameter, the reconstruction of any system with known interaction functions is formulated via a simple matrix equation. We suggest a procedure aimed at optimizing the reconstruction from the time series of length comparable to the characteristic dynamical time scale. Our method also provides a reliable precision estimate. We illustrate the method's implementation via elementary dynamical models, and demonstrate its robustness to both model error and observation error.
The dynamic development of gender variability.
Fausto-Sterling, Anne
2012-01-01
We diagram and discuss theories of gender identity development espoused by the clinical groups represented in this special issue. We contend that theories of origin relate importantly to clinical practice, and argue that the existing clinical theories are under-developed. Therefore, we develop a dynamic systems framework for gender identity development. Specifically, we suggest that critical aspects of presymbolic gender embodiment occur during infancy as part of the synchronous interplay of caregiver-infant dyads. By 18 months, a transition to symbolic representation and the beginning of an internalization of a sense of gender can be detected and consolidation is quite evident by 3 years of age. We conclude by suggesting empirical studies that could expand and test this framework. With the belief that better, more explicit developmental theory can improve clinical practice, we urge that clinicians take a dynamic developmental view of gender identity formation into account.
DEFF Research Database (Denmark)
Kieffer-Kristensen, Rikke; Johansen, Karen Lise Gaardsvig
2013-01-01
to participate. RESULTS: All children were affected by their parents' ABI and the altered family situation. The children's expressions led the authors to identify six themes, including fear of losing the parent, distress and estrangement, chores and responsibilities, hidden loss, coping and support. The main...... the ill parent. These findings contribute to a deeper understanding of the traumatic process of parental ABI that some children experience and emphasize the importance of family-centred interventions that include the children....
Hidden Statistics of Schroedinger Equation
Zak, Michail
2011-01-01
Work was carried out in determination of the mathematical origin of randomness in quantum mechanics and creating a hidden statistics of Schr dinger equation; i.e., to expose the transitional stochastic process as a "bridge" to the quantum world. The governing equations of hidden statistics would preserve such properties of quantum physics as superposition, entanglement, and direct-product decomposability while allowing one to measure its state variables using classical methods.
Formulation of quantized Hamiltonian dynamics in terms of natural variables.
Akimov, Alexey V; Prezhdo, Oleg V
2012-12-14
We present a formulation of quantized Hamiltonian dynamics (QHD) using variables that arise naturally from the Heisenberg equation of motion. The QHD equations are obtained and solved either directly in terms of these generalized variables, or by employing a wavefunction ansatz. The approach avoids a Taylor expansion and other approximations to the potential, leading to more stable dynamics and a higher precision of the calculated quantities. The proposed formulation is also amenable to for analytic and numerical implementations, thus facilitating its use in molecular dynamics simulation.
Pankovic, V; Krmar, M; Radovanovic, M; Pankovic, Vladan; Predojevic, Milan; Krmar, Miodrag; Radovanovic, Milan
2005-01-01
In this work we analyse critically Griffiths's example of the classical superluminal motion of a bug shadow. Griffiths considers that this example is conceptually very close to quantum nonlocality or superluminality,i.e. quantum breaking of the famous Bell inequality. Or, generally, he suggests implicitly an absolute asymmetric duality (subluminality vs. superluminality) principle in any fundamental physical theory.It, he hopes, can be used for a natural interpretation of the quantum mechanics too. But we explain that such Griffiths's interpretation retires implicitly but significantly from usual, Copenhagen interpretation of the standard quantum mechanical formalism. Within Copenhagen interpretation basic complementarity principle represents, in fact, a dynamical symmetry principle (including its spontaneous breaking, i.e. effective hiding by measurement). Similarly, in other fundamental physical theories instead of Griffiths's absolute asymmetric duality principle there is a dynamical symmetry (including it...
A new dynamical variable for the electromagnetic field
Rodríguez-Lara, B M
2008-01-01
Taking into account the characteristics of a free scalar field in elliptic coordinates, a new dynamical variable is found for the free electromagnetic field. The conservation law associated to this variable cannot be obtained by a direct application of standard Noether theorem since the symmetry generator is of second order. Consequences on the expected mechanical behavior of a particle interacting with electromagnetic waves exhibiting such a symmetry are also discussed.
Hidden worlds in quantum physics
Gouesbet, Gérard
2014-01-01
The past decade has witnessed a resurgence in research and interest in the areas of quantum computation and entanglement. This new book addresses the hidden worlds or variables of quantum physics. Author Gérard Gouesbet studied and worked with a former student of Louis de Broglie, a pioneer of quantum physics. His presentation emphasizes the history and philosophical foundations of physics, areas that will interest lay readers as well as professionals and advanced undergraduate and graduate students of quantum physics. The introduction is succeeded by chapters offering background on relevant concepts in classical and quantum mechanics, a brief history of causal theories, and examinations of the double solution, pilot wave, and other hidden-variables theories. Additional topics include proofs of possibility and impossibility, contextuality, non-locality, classification of hidden-variables theories, and stochastic quantum mechanics. The final section discusses how to gain a genuine understanding of quantum mec...
Ravelo-García, A. G.; Saavedra-Santana, P.; Juliá-Serdá, G.; Navarro-Mesa, J. L.; Navarro-Esteva, J.; Álvarez-López, X.; Gapelyuk, A.; Penzel, T.; Wessel, N.
2014-06-01
Many sleep centres try to perform a reduced portable test in order to decrease the number of overnight polysomnographies that are expensive, time-consuming, and disturbing. With some limitations, heart rate variability (HRV) has been useful in this task. The aim of this investigation was to evaluate if inclusion of symbolic dynamics variables to a logistic regression model integrating clinical and physical variables, can improve the detection of subjects for further polysomnographies. To our knowledge, this is the first contribution that innovates in that strategy. A group of 133 patients has been referred to the sleep center for suspected sleep apnea. Clinical assessment of the patients consisted of a sleep related questionnaire and a physical examination. The clinical variables related to apnea and selected in the statistical model were age (p variable based on non-linear dynamics of HRV (p variables. For diagnostic rule based only on clinical and physical variables, the corresponding area under the receiver operating characteristic (ROC) curve was 0.907 (95% confidence interval (CI) = 0.848, 0.967), (sensitivity 87.10% and specificity 80%). For the model including the average of a symbolic dynamic variable, the area under the ROC curve was increased to 0.941 (95% = 0.897, 0.985), (sensitivity 88.71% and specificity 82.86%). In conclusion, symbolic dynamics, coupled with significant clinical and physical variables can help to prioritize polysomnographies in patients with a high probability of apnea. In addition, the processing of the HRV is a well established low cost and robust technique.
The Chern-Simons Number as a Dynamical Variable
Tye, S -H Henry
2016-01-01
In the standard electroweak theory that describes nature, the Chern-Simons number associated with the vacua as well as the unstable sphaleron solutions play a crucial role in the baryon number violating processes. We recall why the Chern-Simons number should be generalized from a set of discrete values to a dynamical (quantum) variable. Via the construction of an appropriate Hopf invariant and the winding number, we discuss how the geometric information in the gauge fields is also captured in the Higgs field. We then discuss the choice of the Hopf variable in relation to the Chern-Simons variable.
DYNAMICAL VARIABLE STRUCTURE CONTROL OF A HELICOPTER IN VERTICAL FLIGHT
Sira-Ramirez, Hebertt; Zribi, Mohamed; Ahmad, Shaheen
1991-01-01
In this article, a dynamical multivariable discontinuous feedback control strategy of the sliding nlode type is proposed for the altitude stabilization of a nonlinear helicopter model in vertical flight. Vlrhile retaining the basic robustness features associated to sliding mode control policies, the proposed approach also results in smoothed out (i.e., non-chattering) input trajectories and controlled state variable responses.
Energy Technology Data Exchange (ETDEWEB)
Landi, Alessandro; Gregori, Fabrizio; Marotta, Nicola; Donnarumma, Pasquale; Delfini, Roberto [University of Rome - Policlinico Umberto I, Department of Neurology and Psychiatry, Division of Neurosurgery, Rome (Italy)
2015-03-26
Dynamic X-rays (DXR) are widely recognized as an effective method to detect lumbar instability (LI). They are usually performed with the patient in standing position (SDXR). In our opinion, standing position inhibits micromovements of the lumbar segment interested by the listhesis, thanks to paravertebral muscles antalgic contraction and augmented tone. We aim to demonstrate that DXR in recumbent position (RDXR), reducing the action of paravertebral muscles, can discover hypermovements not evidenced in SDXR. Between January 2011 and January 2013, we studied 200 consecutive patients with lumbar degenerative disease with MRI, SDXR, and RDXR. We aimed to find a correlation between low back or radicular pain and the presence of a spondylolisthesis not showed by the SDXR, but showed by the RDXR. We analysed 200 patients: of the 133 not pathologic in SDXR, 43 patients (32.3 %) showed an hypermovement in RDXR (p = 0.0001) without any significant correlation between hidden listhesis and age, sex, or level involved. The aim of our study is to determine whether in patients with lumbalgy without evidence of listhesis in SDXR, pain can be attributed to a faccettal syndrome or to a spondylolisthesis. Consequence of pain is augmented muscular tone of the paravertebral musculature, particularly in standing position. Augmented muscular tone tries to inhibit the pain generator, attempting to limit the slippage of the involved segment. In patients examined in RDXR, the tone of paravertebral musculature is reduced, showing the hidden spondylolisthesis. (orig.)
Variational Hidden Conditional Random Fields with Coupled Dirichlet Process Mixtures
Bousmalis, K.; Zafeiriou, S.; Morency, L.P.; Pantic, Maja; Ghahramani, Z.
2013-01-01
Hidden Conditional Random Fields (HCRFs) are discriminative latent variable models which have been shown to successfully learn the hidden structure of a given classification problem. An infinite HCRF is an HCRF with a countably infinite number of hidden states, which rids us not only of the necessit
Borgy, Benjamin; Reboud, Xavier; Peyrard, Nathalie; Sabbadin, Régis; Gaba, Sabrina
2015-01-01
Predicting the population dynamics of annual plants is a challenge due to their hidden seed banks in the field. However, such predictions are highly valuable for determining management strategies, specifically in agricultural landscapes. In agroecosystems, most weed seeds survive during unfavourable seasons and persist for several years in the seed bank. This causes difficulties in making accurate predictions of weed population dynamics and life history traits (LHT). Consequently, it is very difficult to identify management strategies that limit both weed populations and species diversity. In this article, we present a method of assessing weed population dynamics from both standing plant time series data and an unknown seed bank. We use a Hidden Markov Model (HMM) to obtain estimates of over 3,080 botanical records for three major LHT: seed survival in the soil, plant establishment (including post-emergence mortality), and seed production of 18 common weed species. Maximum likelihood and Bayesian approaches were complementarily used to estimate LHT values. The results showed that the LHT provided by the HMM enabled fairly accurate estimates of weed populations in different crops. There was a positive correlation between estimated germination rates and an index of the specialisation to the crop type (IndVal). The relationships between estimated LHTs and that between the estimated LHTs and the ecological characteristics of weeds provided insights into weed strategies. For example, a common strategy to cope with agricultural practices in several weeds was to produce less seeds and increase germination rates. This knowledge, especially of LHT for each type of crop, should provide valuable information for developing sustainable weed management strategies.
Dynamic Analysis of Towed and Variable Length Cable Systems
Institute of Scientific and Technical Information of China (English)
WANG Shu-xin; WANG Yan-hui; LI Xiao-ping
2007-01-01
Towed cable systems are frequently used in marine measurements where the length of the towed cable varies during launch and recovery. In this paper a novel method for modeling variable length cable systems is introduced based on the finite segment formulation. The variable length of the towed cable is described by changing the length of the segment near the towing point and by increasing or decreasing the number of the discrete segments of the cable. In this way, the elastic effects of the cable can be easily handled since geometry and material properties of each segment are kept constant. Experimental results show that the dynamic behavior of the towed cable is consistent between the model and the physical cable. Results show that the model provides numerical efficiency and simulation accuracy for the variable length towed system.
Agulhas leakage dynamics affects decadal variability in Atlantic overturning circulation.
Biastoch, A; Böning, C W; Lutjeharms, J R E
2008-11-27
Predicting the evolution of climate over decadal timescales requires a quantitative understanding of the dynamics that govern the meridional overturning circulation (MOC). Comprehensive ocean measurement programmes aiming to monitor MOC variations have been established in the subtropical North Atlantic (RAPID, at latitude 26.5 degrees N, and MOVE, at latitude 16 degrees N) and show strong variability on intraseasonal to interannual timescales. Observational evidence of longer-term changes in MOC transport remains scarce, owing to infrequent sampling of transoceanic sections over past decades. Inferences based on long-term sea surface temperature records, however, supported by model simulations, suggest a variability with an amplitude of +/-1.5-3 Sv (1 Sv = 10(6) m(3) s(-1)) on decadal timescales in the subtropics. Such variability has been attributed to variations of deep water formation in the sub-arctic Atlantic, particularly the renewal rate of Labrador Sea Water. Here we present results from a model simulation that suggest an additional influence on decadal MOC variability having a Southern Hemisphere origin: dynamic signals originating in the Agulhas leakage region at the southern tip of Africa. These contribute a MOC signal in the tropical and subtropical North Atlantic that is of the same order of magnitude as the northern source. A complete rationalization of observed MOC changes therefore also requires consideration of signals arriving from the south.
Nonlinear Dynamical Modeling and Forecast of ENSO Variability
Feigin, Alexander; Mukhin, Dmitry; Gavrilov, Andrey; Seleznev, Aleksey; Loskutov, Evgeny
2017-04-01
New methodology of empirical modeling and forecast of nonlinear dynamical system variability [1] is applied to study of ENSO climate system. The methodology is based on two approaches: (i) nonlinear decomposition of data [2], that provides low-dimensional embedding for further modeling, and (ii) construction of empirical model in the form of low dimensional random dynamical ("stochastic") system [3]. Three monthly data sets are used for ENSO modeling and forecast: global sea surface temperature anomalies, troposphere zonal wind speed, and thermocline depth; all data sets are limited by 30 S, 30 N and have horizontal resolution 10x10 . We compare results of optimal data decomposition as well as prognostic skill of the constructed models for different combinations of involved data sets. We also present comparative analysis of ENSO indices forecasts fulfilled by our models and by IRI/CPC ENSO Predictions Plume. [1] A. Gavrilov, D. Mukhin, E. Loskutov, A. Feigin, 2016: Construction of Optimally Reduced Empirical Model by Spatially Distributed Climate Data. 2016 AGU Fall Meeting, Abstract NG31A-1824. [2] D. Mukhin, A. Gavrilov, E. Loskutov , A.Feigin, J.Kurths, 2015: Principal nonlinear dynamical modes of climate variability, Scientific Reports, rep. 5, 15510; doi: 10.1038/srep15510. [3] Ya. Molkov, D. Mukhin, E. Loskutov, A. Feigin, 2012: Random dynamical models from time series. Phys. Rev. E, Vol. 85, n.3.
Behavioral variability in an evolutionary theory of behavior dynamics.
Popa, Andrei; McDowell, J J
2016-03-01
McDowell's evolutionary theory of behavior dynamics (McDowell, 2004) instantiates populations of behaviors (abstractly represented by integers) that evolve under the selection pressure of the environment in the form of positive reinforcement. Each generation gives rise to the next via low-level Darwinian processes of selection, recombination, and mutation. The emergent patterns can be analyzed and compared to those produced by biological organisms. The purpose of this project was to explore the effects of high mutation rates on behavioral variability in environments that arranged different reinforcer rates and magnitudes. Behavioral variability increased with the rate of mutation. High reinforcer rates and magnitudes reduced these effects; low reinforcer rates and magnitudes augmented them. These results are in agreement with live-organism research on behavioral variability. Various combinations of mutation rates, reinforcer rates, and reinforcer magnitudes produced similar high-level outcomes (equifinality). These findings suggest that the independent variables that describe an experimental condition interact; that is, they do not influence behavior independently. These conclusions have implications for the interpretation of high levels of variability, mathematical undermatching, and the matching theory. The last part of the discussion centers on a potential biological counterpart for the rate of mutation, namely spontaneous fluctuations in the brain's default mode network.
Dynamical formation of cataclysmic variables in globular clusters
Hong, Jongsuk; Vesperini, Enrico; Belloni, Diogo; Giersz, Mirek
2017-01-01
The formation and evolution of X-ray sources in globular clusters is likely to be affected by the cluster internal dynamics and the stellar interactions in the cluster dense environment. Several observational studies have revealed a correlation between the number of X-ray sources and the stellar encounter rate, and provided evidence of the role of dynamics in the formation of X-ray binaries. We have performed a survey of Monte Carlo simulations aimed at exploring the connection between the dynamics and formation of cataclysmic variables (CVs) and the origin of the observed correlation between the number of these objects, Ncv, and the stellar encounter rate, Γ. The results of our simulations show a correlation between Ncv and Γ, as found in observational data, illustrate the essential role played by the dynamics, and shed light on the dynamical history behind this correlation. CVs in our simulations are more centrally concentrated than single stars with masses close to those of turn-off stars, although this trend is stronger for CVs formed from primordial binaries undergoing exchange encounters, which include a population of more massive CVs absent in the group of CVs formed from binaries not suffering any component exchange.
Dynamic Characteristics of Electrostatically Actuated Shape Optimized Variable Geometry Microbeam
Directory of Open Access Journals (Sweden)
Sha Zhang
2015-01-01
Full Text Available We mainly analyze the dynamic characteristics of electrostatically actuated shape optimized variable geometry microbeam. A nonlinear dynamic model considering midplane stretching, electrostatic force, and electrical field fringing effects is developed. Firstly, we study the static responses of the optimized microbeams under DC polarization voltage. The generalized differential quadrature method (GDQM is used. Secondly, the dynamic responses of the shape optimized microbeams driven by DC and AC voltages are investigated using GDQM in conjunction with Levenberg-Marquardt optimization method. The results show that the more gradual change in width, the larger the resonant frequency and the maximum amplitude at resonance. Then we further discuss in detail how do the maximum width, midsection width, and curvature of the width function affect the frequency response of the microbeams. We find that the amplitude and resonant frequency of the dynamic response are not monotonically increasing as the curvature of the width function increases and there exists a critical curvature. This analysis will be helpful in the optimal design of MEMS actuators. Finally, for more consideration, different residual stress, squeeze-film damping, and fringing effect models are introduced into the governing equation of motion and we compare the corresponding dynamic response.
Dynamical Formation of Cataclysmic Variables in Globular Clusters
Hong, Jongsuk; Belloni, Diogo; Giersz, Mirek
2016-01-01
The formation and evolution of X-ray sources in globular clusters is likely to be affected by the cluster internal dynamics and the stellar interactions in the cluster dense environment.Several observational studies have revealed a correlation between the number of X-ray sources and the stellar encounter rate and provided evidence of the role of dynamics in the formation of X-ray binaries. We have performed a survey of Monte-Carlo simulations aimed at exploring the connection between the dynamics and formation of cataclysmic variables (CVs) and the origin of the observed correlation between the number of these objects, $N_{\\rm cv}$, and the stellar encounter rate, $\\Gamma$.The results of our simulations show a correlation between $N_{\\rm cv}$ and $\\Gamma$ as found in observational data, illustrate the essential role played by dynamics, and shed light on the dynamical history behind this correlation. CVs in our simulations are more centrally concentrated than single stars with masses close to those of turn-off...
Kinematic variability, fractal dynamics and local dynamic stability of treadmill walking
Directory of Open Access Journals (Sweden)
Terrier Philippe
2011-02-01
Full Text Available Abstract Background Motorized treadmills are widely used in research or in clinical therapy. Small kinematics, kinetics and energetics changes induced by Treadmill Walking (TW as compared to Overground Walking (OW have been reported in literature. The purpose of the present study was to characterize the differences between OW and TW in terms of stride-to-stride variability. Classical (Standard Deviation, SD and non-linear (fractal dynamics, local dynamic stability methods were used. In addition, the correlations between the different variability indexes were analyzed. Methods Twenty healthy subjects performed 10 min TW and OW in a random sequence. A triaxial accelerometer recorded trunk accelerations. Kinematic variability was computed as the average SD (MeanSD of acceleration patterns among standardized strides. Fractal dynamics (scaling exponent α was assessed by Detrended Fluctuation Analysis (DFA of stride intervals. Short-term and long-term dynamic stability were estimated by computing the maximal Lyapunov exponents of acceleration signals. Results TW did not modify kinematic gait variability as compared to OW (multivariate T2, p = 0.87. Conversely, TW significantly modified fractal dynamics (t-test, p = 0.01, and both short and long term local dynamic stability (T2 p = 0.0002. No relationship was observed between variability indexes with the exception of significant negative correlation between MeanSD and dynamic stability in TW (3 × 6 canonical correlation, r = 0.94. Conclusions Treadmill induced a less correlated pattern in the stride intervals and increased gait stability, but did not modify kinematic variability in healthy subjects. This could be due to changes in perceptual information induced by treadmill walking that would affect locomotor control of the gait and hence specifically alter non-linear dependencies among consecutive strides. Consequently, the type of walking (i.e. treadmill or overground is important to consider in
Dynamical properties and search of variable stars: NGC 1960
Joshi, Gireesh C
2015-01-01
The total-to-selective extinction RV in the direction of a cluster is found to be 3.12 +/- 0.2 (close to its normal value). We derive the luminosity and mass functions for the cluster main sequence stars. The mass function slope is found to be -2.29 +/- 0.20 which is close to Salpeter value. We find evidence of mass segregation process in the cluster which is not yet dynamically relaxed. We have performed time series photometric observations to detect variable stars within star cluster NGC 1960. The DAOPHOT-II package is utilized to estimate the apparent stellar magnitudes of stars. The secondary standardization method is applied to the transformation of these apparent magnitudes into standard values. The magnitude-time diagrams (light curves) of stars are constructed to identify possible variability nature within them. The stars, having sufficient magnitude variation with time, are considered to be variable stars and their period values have computed through PERIOD04 package. These periodic values of variabl...
Dynamics of a pulsed continuous variable quantum memory
Dantan, A; Grangier, P; Pinard, M; Cviklinski, Jean; Dantan, Aurelien; Grangier, Philippe; Pinard, Michel
2005-01-01
We study the transfer dynamics of non-classical fluctuations of light to the ground-state collective spin components of an atomic ensemble during a pulsed quantum memory sequence, and evaluate the relevant physical quantities to be measured in order to characterize such a quantum memory. We show in particular that the fluctuations stored into the atoms are emitted in temporal modes which are always different than those of the readout pulse, but which can nevertheless be retrieved efficiently using a suitable temporal mode-matching technique. We give a simple toy model - a cavity with variable transmission - which accounts for the behavior of the atomic quantum memory.
A series expansion for the time autocorrelation of dynamical variables
Maiocchi, A M; Giorgilli, A
2011-01-01
We present here a general iterative formula which gives a (formal) series expansion for the time autocorrelation of smooth dynamical variables, for all Hamiltonian systems endowed with an invariant measure. We add some criteria, theoretical in nature, which enable one to decide whether the decay of the correlations is exponentially fast or not. One of these criteria is implemented numerically for the case of the Fermi-Pasta-Ulam system, and we find indications which might suggest a sub-exponentially decay for such a system.
The Ob Estuary (Kara Sea) Coastal Dynamics Interannual Variability Assessment
Kopa-Ovdienko, N.; Volobueva, N.; Ogorodov, S.
2012-04-01
There are several promising gas fields in the Ob Estuary. For their development comprehensive research, including coastal dynamics assessment, is required. To estimate current and speak about future coastal dynamics rates we need to investigate its interannual variability connecting it with variability of major coastal dynamics factors. It is known that in this region one of the main coastal dynamics factors is wave action, which, in turn, depends on wind velocity and direction. Wind data for ice-free period were derived from nearby hydro-meteorological stations. The research was conducted for two sections of the Ob Estuary coast. One section is located on the eastern coast of the estuary (Taz peninsula); the other is located on the western one (Yamal peninsula). Each of these sections is 10 km length. For key-sites of the coast wave-dangerous rhumbs were determined. For ice-free period of each year accumulated summer storm duration (ASSD) - number of hours with strong winds (≥10 m/s) from wave-dangerous directions - was calculated for both sections of coast. Supposing that coast retreat rate is proportional to number of hours with strong winds from wave-dangerous rhumbs, we can approximately assess interannual variability of coast retreat rate. Our research revealed that: 1)There are significant (from hours to a few hundreds of hours) differences in ASSD from year to year due to short ice-free period and high variability of wind velocity and direction. So, we can expect sharp interannual differences in coastal retreat rate. 2)The duration of strong winds from wave-dangerous rhumbs during ice-free period is more on the eastern coast of the estuary than on the western. This goes from the predominance of northern and northwestern winds during ice-free period. These winds cause waves leading to coastal erosion on the eastern coast of estuary and don't cause such waves on the western one. However, we can't draw conclusions about the comparative rates of coastal
Asymmetric acceleration/deceleration dynamics in heart rate variability
Alvarez-Ramirez, J.; Echeverria, J. C.; Meraz, M.; Rodriguez, E.
2017-08-01
The heart rate variability (HRV) is an important physiological signal used either to assess the risk of cardiac death or to model the cardiovascular regulatory dynamics. Asymmetries in HRV data have been observed using 2D Poincare plots, which have been linked to a non-equilibrium operation of the cardiac autonomic system. This work further explores the presence of asymmetries but in the serial correlations of the dynamics of HRV data. To this end, detrended fluctuation analysis (DFA) was used to estimate the Hurst exponent both when the heart rate is accelerating and when it is decelerating. The analysis is conducted using data collected from subjects under normal sinus rhythm (NSR), congestive heart failure (CHF) and atrial fibrillation (AF) . For the NSR cases, it was found that correlations are stronger (p heart rate is accelerating than when it is decelerating over different scales in the range 20-40 beats. In contrast, the opposite behavior was detected for the CHF and AF patients. Possible links between asymmetric correlations in the dynamics and the mechanisms controlling the operation of the heart rate are discussed, as well as their implications for modeling the cardiovascular regulatory dynamics.
Heating up the Galaxy with hidden photons
Energy Technology Data Exchange (ETDEWEB)
Dubovsky, Sergei [Center for Cosmology and Particle Physics, Department of Physics, New York University,New York, NY, 10003 (United States); Hernández-Chifflet, Guzmán [Center for Cosmology and Particle Physics, Department of Physics, New York University,New York, NY, 10003 (United States); Instituto de Física, Facultad de Ingeniería, Universidad de la República,Montevideo, 11300 (Uruguay)
2015-12-29
We elaborate on the dynamics of ionized interstellar medium in the presence of hidden photon dark matter. Our main focus is the ultra-light regime, where the hidden photon mass is smaller than the plasma frequency in the Milky Way. We point out that as a result of the Galactic plasma shielding direct detection of ultra-light photons in this mass range is especially challenging. However, we demonstrate that ultra-light hidden photon dark matter provides a powerful heating source for the ionized interstellar medium. This results in a strong bound on the kinetic mixing between hidden and regular photons all the way down to the hidden photon masses of order 10{sup −20} eV.
Climate dynamics and fluid mechanics: Natural variability and related uncertainties
Ghil, Michael; Simonnet, Eric; 10.1016/j.physd.2008.03.036
2010-01-01
The purpose of this review-and-research paper is twofold: (i) to review the role played in climate dynamics by fluid-dynamical models; and (ii) to contribute to the understanding and reduction of the uncertainties in future climate-change projections. To illustrate the first point, we focus on the large-scale, wind-driven flow of the mid-latitude oceans which contribute in a crucial way to Earth's climate, and to changes therein. We study the low-frequency variability (LFV) of the wind-driven, double-gyre circulation in mid-latitude ocean basins, via the bifurcation sequence that leads from steady states through periodic solutions and on to the chaotic, irregular flows documented in the observations. This sequence involves local, pitchfork and Hopf bifurcations, as well as global, homoclinic ones. The natural climate variability induced by the LFV of the ocean circulation is but one of the causes of uncertainties in climate projections. Another major cause of such uncertainties could reside in the structural ...
QCD in terms of gauge-invariant dynamical variables
Pavel, Hans-Peter
2013-01-01
For a complete description of the physical properties of low-energy QCD, it might be advantageous to first reformulate QCD in terms of gauge-invariant dynamical variables, before applying any approximation schemes. Using a canonical transformation of the dynamical variables, which Abelianises the non-Abelian Gauss-law constraints to be implemented, such a reformulation can be achieved for QCD. The exact implementation of the Gauss laws reduces the colored spin-1 gluons and spin-1/2 quarks to unconstrained colorless spin-0, spin-1, spin-2 and spin-3 glueball fields and colorless Rarita-Schwinger fields respectively. The obtained physical Hamiltonian can then be rewritten into a form, which separates the rotational from the scalar degrees of freedom, and admits a systematic strong-coupling expansion in powers of lambda=g^{-2/3}, equivalent to an expansion in the number of spatial derivatives. The leading-order term in this expansion corresponds to non-interacting hybrid-glueballs, whose low-lying masses can be ...
Water Flow in Karst Aquifer Considering Dynamically Variable Saturation Conduit
Tan, Chaoqun; Hu, Bill X.
2017-04-01
The karst system is generally conceptualized as dual-porosity system, which is characterized by low conductivity and high storage continuum matrix and high conductivity and quick flow conduit networks. And so far, a common numerical model for simulating flow in karst aquifer is MODFLOW2005-CFP, which is released by USGS in 2008. However, the steady-state approach for conduit flow in CFP is physically impractical when simulating very dynamic hydraulics with variable saturation conduit. So, we adopt the method proposed by Reimann et al. (2011) to improve current model, in which Saint-Venant equations are used to model the flow in conduit. Considering the actual background that the conduit is very big and varies along flow path and the Dirichlet boundary varies with rainfall in our study area in Southwest China, we further investigate the influence of conduit diameter and outflow boundary on numerical model. And we also analyze the hydraulic process in multi-precipitation events. We find that the numerical model here corresponds well with CFP for saturated conduit, and it could depict the interaction between matrix and conduit during very dynamic hydraulics pretty well compare with CFP.
Hidden Markov Modeling for Weigh-In-Motion Estimation
Energy Technology Data Exchange (ETDEWEB)
Abercrombie, Robert K [ORNL; Ferragut, Erik M [ORNL; Boone, Shane [ORNL
2012-01-01
This paper describes a hidden Markov model to assist in the weight measurement error that arises from complex vehicle oscillations of a system of discrete masses. Present reduction of oscillations is by a smooth, flat, level approach and constant, slow speed in a straight line. The model uses this inherent variability to assist in determining the true total weight and individual axle weights of a vehicle. The weight distribution dynamics of a generic moving vehicle were simulated. The model estimation converged to within 1% of the true mass for simulated data. The computational demands of this method, while much greater than simple averages, took only seconds to run on a desktop computer.
Wave Dynamics in the Channels of Variable Cross-Section
Directory of Open Access Journals (Sweden)
E.N. Pelinovsky
2017-06-01
Full Text Available Dynamics of long sea waves in the channels of variable depth and variable rectangular cross-section is discussed within various approximations – from the shallow water equations to those of nonlinear dispersion theory. General approach permitting to find traveling (non-reflective waves in inhomogeneous channels is demonstrated within the framework of the shallow water linear theory. The appropriate conditions are determined by solving a system of ordinary differential equations. The so-called self-consistent channel in which the width is connected with its depth in a specific way is studied in detail. Within the linear theory of shallow water, a wave does not reflect from the bottom irregularities. The wave shape remains unchanged on the records of the wave gauges (mareographs fixed along the channel axis, but it varies in space. Nonlinearity and dispersion lead to the wave transformation in such a channel. Within the framework of the shallow water weakly nonlinear theory, the wave shape is described by the Riemann solution, and the wave breaks (gradient catastrophe quicker in the zones of decreasing depth. The modified Korteweg – de Vries equation describing evolution of a solitary wave of weak but finite amplitude in a self-consistent channel, the depth of which can vary arbitrary, is derived. Some examples of a solitary wave transformation in such a channel are analyzed (particularly, a soliton adiabatic transformation in the channel with the slowly varying parameters, and a solitary wave fission into the group of solitons after it has passed the zone where the depth changes abruptly. The obtained solutions extend the class of those represented earlier by S.F. Dotsenko and his colleagues.
Coding with partially hidden Markov models
DEFF Research Database (Denmark)
Forchhammer, Søren; Rissanen, J.
1995-01-01
Partially hidden Markov models (PHMM) are introduced. They are a variation of the hidden Markov models (HMM) combining the power of explicit conditioning on past observations and the power of using hidden states. (P)HMM may be combined with arithmetic coding for lossless data compression. A general...... 2-part coding scheme for given model order but unknown parameters based on PHMM is presented. A forward-backward reestimation of parameters with a redefined backward variable is given for these models and used for estimating the unknown parameters. Proof of convergence of this reestimation is given....... The PHMM structure and the conditions of the convergence proof allows for application of the PHMM to image coding. Relations between the PHMM and hidden Markov models (HMM) are treated. Results of coding bi-level images with the PHMM coding scheme is given. The results indicate that the PHMM can adapt...
Ridolfo, A.; Stassi, R.; Di Stefano, O.
2017-06-01
We show that it is possible to realize quantum superpositions of switched-on and -off strong light-matter interaction in a single quantum dot- semiconductor microcavity system. Such superpositions enable the observation of counterintuitive quantum conditional dynamics effects. Situations are possible where cavity photons as well as the emitter luminescence display exponential decay but their joint detection probability exhibits vacuum Rabi oscillations. Remarkably, these quantum correlations are also present in the nonequilibrium steady state spectra of such coherently driven dissipative quantum systems.
Partially Hidden Markov Models
DEFF Research Database (Denmark)
Forchhammer, Søren Otto; Rissanen, Jorma
1996-01-01
Partially Hidden Markov Models (PHMM) are introduced. They differ from the ordinary HMM's in that both the transition probabilities of the hidden states and the output probabilities are conditioned on past observations. As an illustration they are applied to black and white image compression wher...
Mukherjee, Saumyak; Mondal, Sayantan; Bagchi, Biman
2017-07-01
Since the pioneering works of Pethig, Grant, and Wüthrich on a protein hydration layer, many studies have been devoted to find out if there are any "general and universal" characteristic features that can distinguish water molecules inside the protein hydration layer from bulk. Given that the surface itself varies from protein to protein, and that each surface facing the water is heterogeneous, search for universal features has been elusive. Here, we perform an atomistic molecular dynamics simulation in order to propose and demonstrate that such defining characteristics can emerge if we look not at average properties but the distribution of relaxation times. We present results of calculations of distributions of residence times and rotational relaxation times for four different protein-water systems and compare them with the same quantities in the bulk. The distributions in the hydration layer are unusually broad and log-normal in nature due to the simultaneous presence of peptide backbones that form weak hydrogen bonds, hydrophobic amino acid side chains that form no hydrogen bond, and charged polar groups that form a strong hydrogen bond with the surrounding water molecules. The broad distribution is responsible for the non-exponential dielectric response and also agrees with large specific heat of the hydration water. Our calculations reveal that while the average time constant is just about 2-3 times larger than that of bulk water, it provides a poor representation of the real behaviour. In particular, the average leads to the erroneous conclusion that water in the hydration layer is bulk-like. However, the observed and calculated lower value of static dielectric constant of hydration layer remained difficult to reconcile with the broad distribution observed in dynamical properties. We offer a plausible explanation of these unique properties.
Measuring a hidden coordinate: Rate-exchange kinetics from 3D correlation functions
Berg, Mark A.; Darvin, Jason R.
2016-08-01
Nonexponential kinetics imply the existence of at least one slow variable other than the observable, that is, the system has a "hidden" coordinate. We develop a simple, but general, model that allows multidimensional correlation functions to be calculated for these systems. Homogeneous and heterogeneous mechanisms are both included, and slow exchange of the rates is allowed. This model shows that 2D and 3D correlation functions of the observable measure the distribution and kinetics of the hidden coordinate controlling the rate exchange. Both the mean exchange time and the shape of the exchange relaxation are measurable. However, complications arise because higher correlation functions are sums of multiple "pathways," each of which measures different dynamics. Only one 3D pathway involves exchange dynamics. Care must be used to extract exchange dynamics without contamination from other processes.
Systematic detection of hidden complexities in the unfolding mechanism of a cytosine-rich DNA strand
Smiatek, Jens; Janssen-Müller, Daniel; Friedrich, Rudolf; Heuer, Andreas
2014-01-01
We investigate the unfolding pathway of a cytosine-rich DNA structure via molecular dynamics simulations. By the study of the essential dynamics, we are able to identify a hidden complexity in the description of the dynamics in terms of the first two eigenvectors which are used as collective variables. This complexity can be mainly explained by non-Gaussian fluctuations due to contributions arising from the disregarded set of eigenvectors. We introduce the local non-Gaussian parameter as a tool for the detection of hidden complexities. The usage of this parameter allows a fast and reliable investigation for the determination of the important minimal number of eigenvectors which is needed for a sufficient description of molecular unfolding motion.
Measuring a hidden coordinate: Rate-exchange kinetics from 3D correlation functions.
Berg, Mark A; Darvin, Jason R
2016-08-07
Nonexponential kinetics imply the existence of at least one slow variable other than the observable, that is, the system has a "hidden" coordinate. We develop a simple, but general, model that allows multidimensional correlation functions to be calculated for these systems. Homogeneous and heterogeneous mechanisms are both included, and slow exchange of the rates is allowed. This model shows that 2D and 3D correlation functions of the observable measure the distribution and kinetics of the hidden coordinate controlling the rate exchange. Both the mean exchange time and the shape of the exchange relaxation are measurable. However, complications arise because higher correlation functions are sums of multiple "pathways," each of which measures different dynamics. Only one 3D pathway involves exchange dynamics. Care must be used to extract exchange dynamics without contamination from other processes.
Energy Technology Data Exchange (ETDEWEB)
Liang Liang; Dou Peng; Dong Mingming; Ke Xiaokang; Bian Ningsheng [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Liu Zhen, E-mail: zhenliu@nju.edu.cn [School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)
2009-09-14
Nuclease P1 is an important enzyme that hydrolyzes RNA or single-stranded DNA into nucleotides, and complete digestion is an essential basis for assays based on this enzyme. To digest a doubled-stranded DNA, the enzyme is usually combined with heat denaturing, which breaks doubled-stranded DNA into single strands. This paper presents an un-expected phenomenon that nuclease P1, in combination with heat denaturing, fails to completely digest a DNA sample extracted from salmon sperm. Under the experimental conditions used, at which nuclease P1 can completely digest calf thymus DNA, the digestion yield of salmon sperm DNA was only 89.5%. Spectrometric measurement indicated that a total protein of 4.7% is present in the DNA sample. To explain the reason for this phenomenon, the dynamic kinetic capillary isoelectric focusing (DK-CIEF) approach proposed previously, which allows for the discrimination of different types of protein-DNA interactions and the measurement of the individual dissociation rate constants, was modified and applied to examine possible protein-DNA interactions involved. It was found that a non-specific DNA-protein binding occurs in the sample, the dissociation rate constant for which was measured to be 7.05 {+-} 0.83 x 10{sup -3} s{sup -1}. The formation of DNA-protein complex was suggested to be the main reason for the incomplete digestion of the DNA sample. The modified DK-CIEF approach can be applied as general DNA samples, with the advantages of fast speed and low sample consumption.
Hidden Markov models estimation and control
Elliott, Robert J; Moore, John B
1995-01-01
As more applications are found, interest in Hidden Markov Models continues to grow. Following comments and feedback from colleagues, students and other working with Hidden Markov Models the corrected 3rd printing of this volume contains clarifications, improvements and some new material, including results on smoothing for linear Gaussian dynamics. In Chapter 2 the derivation of the basic filters related to the Markov chain are each presented explicitly, rather than as special cases of one general filter. Furthermore, equations for smoothed estimates are given. The dynamics for the Kalman filte
Institute of Scientific and Technical Information of China (English)
石连栓; 孙焕纯; 冯恩民
2001-01-01
A method for topological optimization of structures with discrete variables subjected to dynamic stress and displacement constraints is presented. By using the quasistatic method, the structure optimization problem under dynamic stress and displacement constraints is converted into one subjected to static stress and displacement constraints. The comprehensive algorithm for topological optimization of structures with discrete variables is used to find the optimum solution.
Event scale variability of mixed alluvial-bedrock channel dynamics
Cook, Kristen; Turowski, Jens; Hovius, Niels
2015-04-01
The relationship between flood events and fluvial behavior is critical for understanding how rivers may respond to the changing hydrologic forcing that may accompany climate change. In mixed bedrock-alluvial rivers, the response of the system to a flood event can be affected by a large number of factors, including coarse sediment availability in the channel, sediment supply from the hillslopes, bedrock-controlled changes in channel width and planform, and the shape of the hydrograph. We use the Daan River Gorge in western Taiwan as a case study to directly observe the effect of individual flood events on channel evolution. The 1200 m long and up to 20 m deep bedrock gorge formed in response to uplift of the riverbed during the 1999 Chi-Chi earthquake. The extremely rapid pace of change ensures that flood events have measurable and often dramatic effects on the channel. Taiwan is subject to both summer typhoons and a spring monsoon, resulting in numerous channel-altering floods with a range of magnitudes. Discharge is therefore highly variable, ranging from 5 to over 2000 m3/s, and changes in the channel are almost entirely driven by discrete flood events. Since early 2009 we have monitored changes in the gorge with repeated RTK GPS surveys, laser rangefinder measurements, and terrestrial LIDAR surveys. Six rainfall stations and five water level gauges provide hydrological data for the basin. We find a distinct relationship between flood magnitude and the magnitude of geomorphic change; however, we do not find a clear relationship between flood characteristics and the direction of change - whether the channel experienced aggradation or erosion in a particular flood. Upstream coarse sediment supply and the influence of abrupt changes in channel width on bedload flux through the gorge appear to have important influences on the channel response. The better understand these controls, we use the model sedFlow (Heimann et al., 2014) to explore the effects of interactions
Emergence of dynamical complexity related to human heart rate variability
Chang, Mei-Chu; Peng, C.-K.; Stanley, H. Eugene
2014-12-01
We apply the refined composite multiscale entropy (MSE) method to a one-dimensional directed small-world network composed of nodes whose states are binary and whose dynamics obey the majority rule. We find that the resulting fluctuating signal becomes dynamically complex. This dynamical complexity is caused (i) by the presence of both short-range connections and long-range shortcuts and (ii) by how well the system can adapt to the noisy environment. By tuning the adaptability of the environment and the long-range shortcuts we can increase or decrease the dynamical complexity, thereby modeling trends found in the MSE of a healthy human heart rate in different physiological states. When the shortcut and adaptability values increase, the complexity in the system dynamics becomes uncorrelated.
Directory of Open Access Journals (Sweden)
Carlen Peter L
2011-04-01
Full Text Available Abstract Background Epilepsy is a common neurological disorder characterized by recurrent electrophysiological activities, known as seizures. Without the appropriate detection strategies, these seizure episodes can dramatically affect the quality of life for those afflicted. The rationale of this study is to develop an unsupervised algorithm for the detection of seizure states so that it may be implemented along with potential intervention strategies. Methods Hidden Markov model (HMM was developed to interpret the state transitions of the in vitro rat hippocampal slice local field potentials (LFPs during seizure episodes. It can be used to estimate the probability of state transitions and the corresponding characteristics of each state. Wavelet features were clustered and used to differentiate the electrophysiological characteristics at each corresponding HMM states. Using unsupervised training method, the HMM and the clustering parameters were obtained simultaneously. The HMM states were then assigned to the electrophysiological data using expert guided technique. Minimum redundancy maximum relevance (mRMR analysis and Akaike Information Criterion (AICc were applied to reduce the effect of over-fitting. The sensitivity, specificity and optimality index of chronic seizure detection were compared for various HMM topologies. The ability of distinguishing early and late tonic firing patterns prior to chronic seizures were also evaluated. Results Significant improvement in state detection performance was achieved when additional wavelet coefficient rates of change information were used as features. The final HMM topology obtained using mRMR and AICc was able to detect non-ictal (interictal, early and late tonic firing, chronic seizures and postictal activities. A mean sensitivity of 95.7%, mean specificity of 98.9% and optimality index of 0.995 in the detection of chronic seizures was achieved. The detection of early and late tonic firing was
Crisis-induced unstable dimension variability in a dynamical system
Energy Technology Data Exchange (ETDEWEB)
Kubo, Geraldo T. [Departamento de Fisica, Universidade Federal do Parana, 81531-990, Curitiba, Parana (Brazil); Viana, Ricardo L. [Departamento de Fisica, Universidade Federal do Parana, 81531-990, Curitiba, Parana (Brazil)], E-mail: viana@fisica.ufpr.br; Lopes, Sergio R. [Departamento de Fisica, Universidade Federal do Parana, 81531-990, Curitiba, Parana (Brazil); Grebogi, Celso [Department of Physics, King' s College, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom)
2008-08-18
Unstable dimension variability is an extreme form of non-hyperbolic behavior in chaotic systems whose attractors have periodic orbits with a different number of unstable directions. We propose a new mechanism for the onset of unstable dimension variability based on an interior crisis, or a collision between a chaotic attractor and an unstable periodic orbit. We give a physical example by considering a high-dimensional dissipative physical system driven by impulsive periodic forcing.
Dynamic heterogeneity and life history variability in the kittiwake
DEFF Research Database (Denmark)
Steiner, Uli; Tuljapurkar, Shripad; Orzack, Steven Hecht
2010-01-01
differences. We quantify the diversity in life histories by metrics computed from the generating stochastic process. 4. We show how dynamic heterogeneity can be used as a null model and also how it can lead to positive associations between reproduction and survival across the life span. 5. We believe our......1. Understanding the evolution of life histories requires an assessment of the process that generates variation in life histories. Within-population heterogeneity of life histories can be dynamically generated by stochastic variation of reproduction and survival or be generated by individual...... differences that are fixed at birth. 2. We show for the kittiwake that dynamic heterogeneity is a sufficient explanation of observed variation of life histories. 3. The total heterogeneity in life histories has a small contribution from reproductive stage dynamics and a large contribution from survival...
Dynamic height: A key variable for identifying the spawning habitat of small pelagic fishes
Asch, Rebecca G.; Checkley, David M., Jr.
2013-01-01
Small pelagic fishes off southern California exhibit interannual variations in the regions they occupy. An enhanced understanding of these fluctuations could improve fisheries management and predictions of fish's responses to climate change. We investigated dynamic height as a variable for identifying the spawning habitat of northern anchovy (Engraulis mordax), Pacific sardine (Sardinops sagax), and jack mackerel (Trachurus symmetricus). During cruises between 1998 and 2004, dynamic height was calculated from temperature and salinity profiles, while fish egg concentration was measured with obliquely towed bongo nets and the Continuous, Underway Fish Egg Sampler. Dynamic height ranged between 68 and 108 cm, with values increasing offshore. The greatest probability of encountering anchovy, sardine, and jack mackerel eggs occurred at dynamic heights of 79-83 cm, 84-89 cm, and 89-99 cm, respectively. Four mechanisms were proposed to explain how dynamic height affects egg distribution: (1) dynamic height is a proxy for upper water column temperature and salinity, which are known to influence spawning habitat. (2) Low dynamic heights are indicative of coastal upwelling, which increases primary and secondary productivity. (3) Egg concentration is greater at dynamic heights coincident with geostrophic currents that transport larvae to favorable habitats. (4) Eddies delineated by dynamic height contours retain eggs in productive habitats. To evaluate these mechanisms, a generalized linear model was constructed using dynamic height, temperature, salinity, chlorophyll, zooplankton volume, geostrophic currents, and eddies as independent variables. Dynamic height explained more variance than any other variable in models of sardine and anchovy spawning habitat. Together temperature, salinity, and chlorophyll accounted for 80-95% of the dynamic height effect, emphasizing the importance of the first two mechanisms. However, dynamic height remained statistically significant in the
The structural and dynamical variables of pentane isomers
Patel, Tarika K.; Vaghela, M. V.; Gajjar, P. N.
2016-05-01
We derived structural and dynamical properties of pentane isomers: normal pentane, iso-pentane and neo pentane for liquid and gaseous state. We use molecular dynamics simulation to calculate the dynamical properties of pentane isomers for number of particles 729 using the intermolecular potential and force due to Lenard Jones potential. The computations also include mean square displacement and self diffusion co-efficient using Einstein relation. In structural properties, structure factor and phonon frequency are obtaining from P Y Method and Hubbard and Beeby Approach respectively. The Intermolecular potential and self diffusion co-efficient depend on the branching in the structure. The pair correlation function and phonon dispersion curves revels the complex structure of neo-pentane with respect to iso-pentane and n-pentane.
Hidden circuits and argumentation
Leinonen, Risto; Kesonen, Mikko H. P.; Hirvonen, Pekka E.
2016-11-01
Despite the relevance of DC circuits in everyday life and schools, they have been shown to cause numerous learning difficulties at various school levels. In the course of this article, we present a flexible method for teaching DC circuits at lower secondary level. The method is labelled as hidden circuits, and the essential idea underlying hidden circuits is in hiding the actual wiring of DC circuits, but to make their behaviour evident for pupils. Pupils are expected to find out the wiring of the circuit which should enhance their learning of DC circuits. We present two possible ways to utilise hidden circuits in a classroom. First, they can be used to test and enhance pupils’ conceptual understanding when pupils are expected to find out which one of the offered circuit diagram options corresponds to the actual circuit shown. This method aims to get pupils to evaluate the circuits holistically rather than locally, and as a part of that aim this method highlights any learning difficulties of pupils. Second, hidden circuits can be used to enhance pupils’ argumentation skills with the aid of argumentation sheet that illustrates the main elements of an argument. Based on the findings from our co-operating teachers and our own experiences, hidden circuits offer a flexible and motivating way to supplement teaching of DC circuits.
Supersymmetric leptogenesis and light hidden sectors
Weniger, Christoph
2010-01-01
Thermal leptogenesis and supergravity are attractive scenarios for physics beyond the standard model. However, it is well known that the super-weak interaction of the gravitino often leads to problems with primordial nucleosynthesis in the standard scenario of matter parity conserving MSSM + three right-handed neutrinos. We will present and compare two related solutions to these problems: 1) The conflict between BBN and leptogenesis can be avoided in presence of a hidden sector with light supersymmetric particles which open new decay channels for the dangerous long-lived particles. 2) If there is a condensate in the hidden sector, such additional decay channels can be alternatively opened by dynamical breaking of matter parity in the hidden sector.
Active optics for high-dynamic variable curvature mirrors
Hugot, Emmanuel; Lemaitre, Gerard R; Madec, Fabrice; Vives, Sebastien; Chardin, Elodie; Mignant, David Le; Cuby, Jean Gabriel
2014-01-01
Variable curvature mirrors of large amplitude are designed by using finite element analysis. The specific case studied reaches at least a 800 {\\mu}m sag with an optical quality better than {\\lambda}/5 over a 120 mm clear aperture. We highlight the geometrical nonlinearity and the plasticity effect.
Inverse problem for multivariate time series using dynamical latent variables
Zamparo, M.; Stramaglia, S.; Banavar, J. R.; Maritan, A.
2012-06-01
Factor analysis is a well known statistical method to describe the variability among observed variables in terms of a smaller number of unobserved latent variables called factors. While dealing with multivariate time series, the temporal correlation structure of data may be modeled by including correlations in latent factors, but a crucial choice is the covariance function to be implemented. We show that analyzing multivariate time series in terms of latent Gaussian processes, which are mutually independent but with each of them being characterized by exponentially decaying temporal correlations, leads to an efficient implementation of the expectation-maximization algorithm for the maximum likelihood estimation of parameters, due to the properties of block-tridiagonal matrices. The proposed approach solves an ambiguity known as the identifiability problem, which renders the solution of factor analysis determined only up to an orthogonal transformation. Samples with just two temporal points are sufficient for the parameter estimation: hence the proposed approach may be applied even in the absence of prior information about the correlation structure of latent variables by fitting the model to pairs of points with varying time delay. Our modeling allows one to make predictions of the future values of time series and we illustrate our method by applying it to an analysis of published gene expression data from cell culture HeLa.
Hidden symmetries in dilaton-axion gravity
Kechkin, O V
1996-01-01
Four--dimensional Einstein--Maxwell--dilaton--axion system restricted to space--times with one non--null Killing symmetry is formulated as the three--dimensional gravity coupled sigma--model. Several alternative representations are discussed and the associated hidden symmetries are revealed. The action of target space isometries on the initial set of (non--dualized ) variables is found. New mulicenter solutions are obtained via generating technique based on the formulation in terms of the non--dualized variables.
How Hidden Can Be Even More Hidden?
Fraczek, Wojciech; Szczypiorski, Krzysztof
2011-01-01
The paper presents Deep Hiding Techniques (DHTs) that define general techniques that can be applied to every network steganography method to improve its undetectability and make steganogram extraction harder to perform. We define five groups of techniques that can make steganogram less susceptible to detection and extraction. For each of the presented group, examples of the usage are provided based on existing network steganography methods. To authors' best knowledge presented approach is the first attempt in the state of the art to systematically describe general solutions that can make steganographic communication more hidden and steganogram extraction harder to perform.
Dynamics relationship between stock prices and economic variables in Malaysia
Chun, Ooi Po; Arsad, Zainudin; Huen, Tan Bee
2014-07-01
Knowledge on linkages between stock prices and macroeconomic variables are essential in the formulation of effective monetary policy. This study investigates the relationship between stock prices in Malaysia (KLCI) with four selected macroeconomic variables, namely industrial production index (IPI), quasi money supply (MS2), real exchange rate (REXR) and 3-month Treasury bill (TRB). The variables used in this study are monthly data from 1996 to 2012. Vector error correction (VEC) model and Kalman filter (KF) technique are utilized to assess the impact of macroeconomic variables on the stock prices. The results from the cointegration test revealed that the stock prices and macroeconomic variables are cointegrated. Different from the constant estimate from the static VEC model, the KF estimates noticeably exhibit time-varying attributes over the entire sample period. The varying estimates of the impact coefficients should be better reflect the changing economic environment. Surprisingly, IPI is negatively related to the KLCI with the estimates of the impact slowly increase and become positive in recent years. TRB is found to be generally negatively related to the KLCI with the impact fluctuating along the constant estimate of the VEC model. The KF estimates for REXR and MS2 show a mixture of positive and negative impact on the KLCI. The coefficients of error correction term (ECT) are negative in majority of the sample period, signifying the stock prices responded to stabilize any short term deviation in the economic system. The findings from the KF model indicate that any implication that is based on the usual static model may lead to authorities implementing less appropriate policies.
Dynamics of a pulsed continuous-variable quantum memory
DEFF Research Database (Denmark)
Dantan, Aurelien Romain; Cviklinski, Jean; Pinard, Michel
2006-01-01
We study the transfer dynamics of nonclassical fluctuations of light to the ground-state collective spin components of an atomic ensemble during a pulsed quantum memory sequence, and evaluate the relevant physical quantities to be measured in order to characterize such a quantum memory. We show i...
2-D Chemical-Dynamical Modeling of Venus's Sulfur Variability
Bierson, Carver J.; Zhang, Xi
2016-10-01
Over the last decade a combination of ground based and Venus Express observations have been made of the concentration of sulfur species in Venus's atmosphere, both above [1, 2] and below the clouds [3, 4]. These observations put constraints on both the vertical and meridional variations of the major sulfur species in Venus's atmosphere.. It has also been observed that SO2 concentrations varies on both timescales of hours and years [1,4]. The spatial and temporal distribution of tracer species is owing to two possibilities: mutual chemical interaction and dynamical tracer transport.Previous Chemical modeling of Venus's middle atmosphere has only been explored in 1-D. We will present the first 2-D (altitude and latitude) chemical-dynamical model for Venus's middle atmosphere. The sulfur chemistry is based on of the 1D model of Zhang et al. 2012 [5]. We do model runs over multiple Venus decades testing two scenarios: first one with varying sulfur fluxes from below, and second with secular dynamical perturbations in the atmosphere [6]. By comparing to Venus Express and ground based observations, we put constraints on the dynamics of Venus's middle atmosphere.References: [1] Belyaev et al. Icarus 2012 [2] Marcq et al. Nature geoscience, 2013 [3] Marcq et al. JGR:Planets, 2008 [4] Arney et al. JGR:Planets, 2014 [5] Zhang et al. Icarus 2012 [6] Parish et al. Icarus 2012
Hidden scale invariance of metals
DEFF Research Database (Denmark)
Hummel, Felix; Kresse, Georg; Dyre, Jeppe C.
2015-01-01
available. Hidden scale invariance is demonstrated in detail for magnesium by showing invariance of structure and dynamics. Computed melting curves of period three metals follow curves with invariance (isomorphs). The experimental structure factor of magnesium is predicted by assuming scale invariant...... of metals making the condensed part of the thermodynamic phase diagram effectively one dimensional with respect to structure and dynamics. DFT computed density scaling exponents, related to the Grüneisen parameter, are in good agreement with experimental values for the 16 elements where reliable data were......Density functional theory (DFT) calculations of 58 liquid elements at their triple point show that most metals exhibit near proportionality between the thermal fluctuations of the virial and the potential energy in the isochoric ensemble. This demonstrates a general “hidden” scale invariance...
The SHiP Experiment is a new general-purpose fixed target facility at the SPS to search for hidden particles as predicted by a very large number of recently elaborated models of Hidden Sectors which are capable of accommodating dark matter, neutrino oscillations, and the origin of the full baryon asymmetry in the Universe. Specifically, the experiment is aimed at searching for very weakly interacting long lived particles including Heavy Neutral Leptons - right-handed partners of the active neutrinos; light supersymmetric particles - sgoldstinos, etc.; scalar, axion and vector portals to the hidden sector. The high intensity of the SPS and in particular the large production of charm mesons with the 400 GeV beam allow accessing a wide variety of light long-lived exotic particles of such models and of SUSY. Moreover, the facility is ideally suited to study the interactions of tau neutrinos.
Temporal dynamics and leaf trait variability in Neotropical dry forests
Hesketh, Michael Sean
This thesis explores the variability of leaf traits resulting from changes in season, ecosystem successional stage, and site characteristics. In chapter two, I present a review of the use of remote sensing analysis for the evaluation of Neotropical dry forests. Here, I stress the conclusion, drawn from studies on land cover characterization, biodiversity assessment, and evaluation of forest structural characteristics, that addressing temporal variability in spectral properties is an essential element in the monitoring of these ecosystems. Chapter three describes the effect of wet-dry seasonality on spectral classification of tree and liana species. Highly accurate classification (> 80%) was possible using data from either the wet or dry season. However, this accuracy decreased by a factor of ten when data from the wet season was classified using an algorithm trained on the dry, or vice versa. I also address the potential creation of a spectral taxonomy of species, but found that any clustering based on spectral properties resulted in markedly different arrangements in the wet and dry seasons. In chapter 4, I address the variation present in both physical and spectral leaf traits according to changes in forest successional stage at dry forest sites in Mexico and Costa Rica. I found significant differences in leaf traits between successional stages, but more strongly so in Costa Rica. This variability deceased the accuracy of spectral classification of tree species by a factor of four when classifying data using an algorithm trained on a different successional stage. Chapter 5 shows the influence of seasonality and succession on trait variability in Mexico. Differences in leaf traits between successional stages were found to be greater during the dry season, but were sufficient in both seasons to negatively influence spectral classification of tree species. Throughout this thesis, I show clear and unambiguous evidence of the variability of key physical and spectral
Dynamic variables of science classroom discourse in relation to teachers' instructional beliefs
National Research Council Canada - National Science Library
Kaya, Sibel
2014-01-01
The current study examines if the occurence of dynamic variables namely, authentic questions, uptake, high-level evaluation and student questions in primary science classrooms vary by teachers' instructional beliefs...
Collective dynamics of self-propelled particles with variable speed
Mishra, Shradha; Couzin, Iain D; Huepe, Cristián
2012-01-01
Understanding the organization of collective motion in biological systems is an ongoing challenge. In this Paper we consider a minimal model of self-propelled particles with variable speed. Inspired by experimental data from schooling fish, we introduce a power-law dependency of the speed of each particle on the degree of polarization order in its neighborhood. We derive analytically a coarse-grained continuous approximation for this model and find that, while the variable speed rule does not change the details of the ordering transition leading to collective motion, it induces an inverse power-law correlation between the speed or the local polarization order and the local density. Using numerical simulations, we verify the range of validity of this continuous description and explore regimes beyond it. We discover, in disordered states close to the transition, a phase-segregated regime where most particles cluster into almost static groups surrounded by isolated high-speed particles. We argue that the mechani...
Generalized Scaling and the Master Variable for Brownian Magnetic Nanoparticle Dynamics.
Directory of Open Access Journals (Sweden)
Daniel B Reeves
Full Text Available Understanding the dynamics of magnetic particles can help to advance several biomedical nanotechnologies. Previously, scaling relationships have been used in magnetic spectroscopy of nanoparticle Brownian motion (MSB to measure biologically relevant properties (e.g., temperature, viscosity, bound state surrounding nanoparticles in vivo. Those scaling relationships can be generalized with the introduction of a master variable found from non-dimensionalizing the dynamical Langevin equation. The variable encapsulates the dynamical variables of the surroundings and additionally includes the particles' size distribution and moment and the applied field's amplitude and frequency. From an applied perspective, the master variable allows tuning to an optimal MSB biosensing sensitivity range by manipulating both frequency and field amplitude. Calculation of magnetization harmonics in an oscillating applied field is also possible with an approximate closed-form solution in terms of the master variable and a single free parameter.
Internal variability of a dynamically downscaled climate over North America
Wang, Jiali; Bessac, Julie; Kotamarthi, Rao; Constantinescu, Emil; Drewniak, Beth
2017-09-01
This study investigates the internal variability (IV) of a regional climate model, and considers the impacts of horizontal resolution and spectral nudging on the IV. A 16-member simulation ensemble was conducted using the Weather Research Forecasting model for three model configurations. Ensemble members included simulations at spatial resolutions of 50 and 12 km without spectral nudging and simulations at a spatial resolution of 12 km with spectral nudging. All the simulations were generated over the same domain, which covered much of North America. The degree of IV was measured as the spread between the individual members of the ensemble during the integration period. The IV of the 12 km simulation with spectral nudging was also compared with a future climate change simulation projected by the same model configuration. The variables investigated focus on precipitation and near-surface air temperature. While the IVs show a clear annual cycle with larger values in summer and smaller values in winter, the seasonal IV is smaller for a 50-km spatial resolution than for a 12-km resolution when nudging is not applied. Applying a nudging technique to the 12-km simulation reduces the IV by a factor of two, and produces smaller IV than the simulation at 50 km without nudging. Applying a nudging technique also changes the geographic distributions of IV in all examined variables. The IV is much smaller than the inter-annual variability at seasonal scales for regionally averaged temperature and precipitation. The IV is also smaller than the projected changes in air-temperature for the mid- and late twenty-first century. However, the IV is larger than the projected changes in precipitation for the mid- and late twenty-first century.
Schwarz, Matthias; Redondo, Javier; Ringwald, Andreas; Wiedemann, Guenter
2011-01-01
The Solar Hidden Photon Search (SHIPS) is a joint astroparticle project of the Hamburger Sternwarte and DESY. The main target is to detect the solar emission of a new species of particles, so called Hidden Photons (HPs). Due to kinetic mixing, photons and HPs can convert into each other as they propagate. A small number of solar HPs - originating from photon to HP oscillations in the interior of the Sun - can be converted into photons in a long vacuum pipe pointing to the Sun - the SHIPS helioscope.
Energy Technology Data Exchange (ETDEWEB)
Schwarz, Matthias; Wiedemann, Guenter [Hamburg Univ. (Germany). Sternwarte; Lindner, Axel; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Redondo, Javier [Max-Planck-Institut fuer Physik und Astrophysik, Muenchen (Germany)
2011-11-15
The Solar Hidden Photon Search (SHIPS) is a joint astroparticle project of the Hamburger Sternwarte and DESY. The main target is to detect the solar emission of a new species of particles, so called Hidden Photons (HPs). Due to kinetic mixing, photons and HPs can convert into each other as they propagate. A small number of solar HPs - originating from photon to HP oscillations in the interior of the Sun - can be converted into photons in a long vacuum pipe pointing to the Sun - the SHIPS helioscope. (orig.)
Entanglement Growth in Quench Dynamics with Variable Range Interactions
Directory of Open Access Journals (Sweden)
J. Schachenmayer
2013-09-01
Full Text Available Studying entanglement growth in quantum dynamics provides both insight into the underlying microscopic processes and information about the complexity of the quantum states, which is related to the efficiency of simulations on classical computers. Recently, experiments with trapped ions, polar molecules, and Rydberg excitations have provided new opportunities to observe dynamics with long-range interactions. We explore nonequilibrium coherent dynamics after a quantum quench in such systems, identifying qualitatively different behavior as the exponent of algebraically decaying spin-spin interactions in a transverse Ising chain is varied. Computing the buildup of bipartite entanglement as well as mutual information between distant spins, we identify linear growth of entanglement entropy corresponding to propagation of quasiparticles for shorter-range interactions, with the maximum rate of growth occurring when the Hamiltonian parameters match those for the quantum phase transition. Counterintuitively, the growth of bipartite entanglement for long-range interactions is only logarithmic for most regimes, i.e., substantially slower than for shorter-range interactions. Experiments with trapped ions allow for the realization of this system with a tunable interaction range, and we show that the different phenomena are robust for finite system sizes and in the presence of noise. These results can act as a direct guide for the generation of large-scale entanglement in such experiments, towards a regime where the entanglement growth can render existing classical simulations inefficient.
Heuristic techniques for the analysis of variability as a dynamic aspect of change
Van Dijk, M.W.G.; Van Geert, P.
2011-01-01
Due to the influence of dynamic systems and microgenetic perspectives, variability is nowadays often seen as an important phenomenon that helps us understand the underlying mechanisms of development. This paper aims at demonstrating several simple techniques that can be used to analyse variability i
Dynamic Quantum Allocation and Swap-Time Variability in Time-Sharing Operating Systems.
Bhat, U. Narayan; Nance, Richard E.
The effects of dynamic quantum allocation and swap-time variability on central processing unit (CPU) behavior are investigated using a model that allows both quantum length and swap-time to be state-dependent random variables. Effective CPU utilization is defined to be the proportion of a CPU busy period that is devoted to program processing, i.e.…
Heuristic techniques for the analysis of variability as a dynamic aspect of change
Van Dijk, M.W.G.; Van Geert, P.
Due to the influence of dynamic systems and microgenetic perspectives, variability is nowadays often seen as an important phenomenon that helps us understand the underlying mechanisms of development. This paper aims at demonstrating several simple techniques that can be used to analyse variability
Addressing Thermal and Performance Variability Issues in Dynamic Processors
Energy Technology Data Exchange (ETDEWEB)
Yoshii, Kazutomo [Argonne National Lab. (ANL), Argonne, IL (United States); Llopis, Pablo [Univ. Carlos III de Madrid (Spain); Zhang, Kaicheng [Northwestern Univ., Evanston, IL (United States); Luo, Yingyi [Northwestern Univ., Evanston, IL (United States); Ogrenci-Memik, Seda [Northwestern Univ., Evanston, IL (United States); Memik, Gokhan [Northwestern Univ., Evanston, IL (United States); Sankaran, Rajesh [Argonne National Lab. (ANL), Argonne, IL (United States); Beckman, Pete [Argonne National Lab. (ANL), Argonne, IL (United States)
2017-03-01
As CMOS scaling nears its end, parameter variations (process, temperature and voltage) are becoming a major concern. To overcome parameter variations and provide stability, modern processors are becoming dynamic, opportunistically adjusting voltage and frequency based on thermal and energy constraints, which negatively impacts traditional bulk-synchronous parallelism-minded hardware and software designs. As node-level architecture is growing in complexity, implementing variation control mechanisms only with hardware can be a challenging task. In this paper we investigate a software strategy to manage hardwareinduced variations, leveraging low-level monitoring/controlling mechanisms.
Methodology Aspects of Quantifying Stochastic Climate Variability with Dynamic Models
Nuterman, Roman; Jochum, Markus; Solgaard, Anna
2015-04-01
The paleoclimatic records show that climate has changed dramatically through time. For the past few millions of years it has been oscillating between ice ages, with large parts of the continents covered with ice, and warm interglacial periods like the present one. It is commonly assumed that these glacial cycles are related to changes in insolation due to periodic changes in Earth's orbit around Sun (Milankovitch theory). However, this relationship is far from understood. The insolation changes are so small that enhancing feedbacks must be at play. It might even be that the external perturbation only plays a minor role in comparison to internal stochastic variations or internal oscillations. This claim is based on several shortcomings in the Milankovitch theory: Prior to one million years ago, the duration of the glacial cycles was indeed 41,000 years, in line with the obliquity cycle of Earth's orbit. This duration changed at the so-called Mid-Pleistocene transition to approximately 100,000 years. Moreover, according to Milankovitch's theory the interglacial of 400,000 years ago should not have happened. Thus, while prior to one million years ago the pacing of these glacial cycles may be tied to changes in Earth's orbit, we do not understand the current magnitude and phasing of the glacial cycles. In principle it is possible that the glacial/interglacial cycles are not due to variations in Earth's orbit, but due to stochastic forcing or internal modes of variability. We present a new method and preliminary results for a unified framework using a fully coupled Earth System Model (ESM), in which the leading three ice age hypotheses will be investigated together. Was the waxing and waning of ice sheets due to an internal mode of variability, due to variations in Earth's orbit, or simply due to a low-order auto-regressive process (i.e., noise integrated by system with memory)? The central idea is to use the Generalized Linear Models (GLM), which can handle both
Heart rate variability dynamics for the prognosis of cardiovascular risk.
Directory of Open Access Journals (Sweden)
Juan F Ramirez-Villegas
Full Text Available Statistical, spectral, multi-resolution and non-linear methods were applied to heart rate variability (HRV series linked with classification schemes for the prognosis of cardiovascular risk. A total of 90 HRV records were analyzed: 45 from healthy subjects and 45 from cardiovascular risk patients. A total of 52 features from all the analysis methods were evaluated using standard two-sample Kolmogorov-Smirnov test (KS-test. The results of the statistical procedure provided input to multi-layer perceptron (MLP neural networks, radial basis function (RBF neural networks and support vector machines (SVM for data classification. These schemes showed high performances with both training and test sets and many combinations of features (with a maximum accuracy of 96.67%. Additionally, there was a strong consideration for breathing frequency as a relevant feature in the HRV analysis.
Dynamic Variability of Isometric Action Tremor in Precision Pinching
Directory of Open Access Journals (Sweden)
Tim Eakin
2012-01-01
Full Text Available Evolutionary development of isometric force impulse frequencies, power, and the directional concordance of changes in oscillatory tremor during performance of a two-digit force regulation task was examined. Analyses compared a patient group having tremor confounding volitional force regulation with a control group having no neuropathological diagnosis. Dependent variables for tremor varied temporally and spatially, both within individual trials and across trials, across individuals, across groups, and between digits. Particularly striking findings were magnitude increases during approaches to cue markers and shifts in the concordance phase from pinching toward rigid sway patterns as the magnitude increased. Magnitudes were significantly different among trace line segments of the task and were characterized by differences in relative force required and by the task progress with respect to cue markers for beginning, reversing force change direction, or task termination. The main systematic differences occurred during cue marker approach and were independent of trial sequence order.
Dynamics of a seismogenic fault subject to variable strain rate
Directory of Open Access Journals (Sweden)
M. Dragoni
2011-06-01
Full Text Available The behaviour of seismogenic faults is generally investigated under the assumption that they are subject to a constant strain rate. We consider the effect of a slowly variable strain rate on the recurrence times of earthquakes generated by a single fault. To this aim a spring-block system is employed as a low-order analog of the fault. Two cases are considered: a sinusoidal oscillation in the driver velocity and a monotonic change from one velocity value to another. In the first case, a study of the orbit of the system in the state space suggests that the seismic activity of the equivalent fault is organized into cycles that include several earthquakes and repeat periodically. Within each cycle the recurrence times oscillate about an average value equal to the recurrence period for constant strain rate. In the second case, the recurrence time changes gradually from the value before the transition to the value following it. Asymptotic solutions are also given, approximating the case when the amplitude of the oscillation or of the monotonic change is much smaller than the average driver velocity and the period of oscillation or the duration of the transition is much longer than the recurrence times of block motions. If the system is not isolated but is subject to perturbations in stress, the perturbation anticipates or delays the subsequent earthquake. The effects of stress perturbations in the two cases of strain rate oscillations and monotonic change are considered.
Evidence for Dynamical Changes in a Transitional Protoplanetary Disk with Mid-infrared Variability
Muzerolle, James; Balog, Zoltan; Furlan, Elise; Smith, Paul S; Allen, Lori; Calvet, Nuria; D'Alessio, Paola; Megeath, S Thomas; Muench, August; Rieke, George H; Sherry, William H
2009-01-01
We present multi-epoch Spitzer Space Telescope observations of the transitional disk LRLL 31 in the 2-3 Myr-old star forming region IC 348. Our measurements show remarkable mid-infrared variability on timescales as short as one week. The infrared continuum emission exhibits systematic wavelength-dependent changes that suggest corresponding dynamical changes in the inner disk structure and variable shadowing of outer disk material. We propose several possible sources for the structural changes, including a variable accretion rate or a stellar or planetary companion embedded in the disk. Our results indicate that variability studies in the infrared can provide important new constraints on protoplanetary disk behavior.
Suppressing the QCD axion abundance by hidden monopoles
Energy Technology Data Exchange (ETDEWEB)
Kawasaki, Masahiro [Tokyo Univ., Chiba (Japan). Inst. for Cosmic Ray Research; Tokyo Univ., Chiba (Japan). Kavli IPMU (WPI), UTIAS; Takahashi, Fuminobu [Tokyo Univ., Miyagi (Japan). Dept. of Physics; Tokyo Univ., Chiba (Japan). Kavli IPMU (WPI), UTIAS; Yamada, Masaki [Tokyo Univ., Chiba (Japan). Inst. for Cosmic Ray Research; Tokyo Univ., Chiba (Japan). Kavli IPMU (WPI), UTIAS; DESY Hamburg (Germany)
2015-11-15
We study the Witten effect of hidden monopoles on the QCD axion dynamics, and show that its abundance as well as isocurvature perturbations can be significantly suppressed if there is a sufficient amount of hidden monopoles. When the hidden monopoles make up a significant fraction of dark matter, the Witten effect suppresses the abundance of axion with the decay constant smaller than 10{sup 12} GeV. The cosmological domain wall problem of the QCD axion can also be avoided, relaxing the upper bound on the decay constant when the Peccei-Quinn symmetry is spontaneously broken after inflation.
Suppressing the QCD axion abundance by hidden monopoles
Directory of Open Access Journals (Sweden)
Masahiro Kawasaki
2016-02-01
Full Text Available We study the Witten effect of hidden monopoles on the QCD axion dynamics, and show that its abundance as well as isocurvature perturbations can be significantly suppressed if there is a sufficient amount of hidden monopoles. When the hidden monopoles make up a significant fraction of dark matter, the Witten effect suppresses the abundance of axion with the decay constant smaller than 1012GeV. The cosmological domain wall problem of the QCD axion can also be avoided, relaxing the upper bound on the decay constant when the Peccei–Quinn symmetry is spontaneously broken after inflation.
DEFF Research Database (Denmark)
Krogh, Anders Stærmose; Riis, Søren Kamaric
1999-01-01
A general framework for hybrids of hidden Markov models (HMMs) and neural networks (NNs) called hidden neural networks (HNNs) is described. The article begins by reviewing standard HMMs and estimation by conditional maximum likelihood, which is used by the HNN. In the HNN, the usual HMM probability...... parameters are replaced by the outputs of state-specific neural networks. As opposed to many other hybrids, the HNN is normalized globally and therefore has a valid probabilistic interpretation. All parameters in the HNN are estimated simultaneously according to the discriminative conditional maximum...... likelihood criterion. The HNN can be viewed as an undirected probabilistic independence network (a graphical model), where the neural networks provide a compact representation of the clique functions. An evaluation of the HNN on the task of recognizing broad phoneme classes in the TIMIT database shows clear...
Królikowski, Wojciech
2016-01-01
A hypothetic Hidden Sector of the Universe, consisting of sterile fermions ("sterinos") and sterile mediating bosons ("sterons") of mass dimension 1 (not 2!) - the last described by an antisymmetric tensor field - requires to exist also a scalar isovector and scalar isoscalar in order to be able to construct electroweak invariant coupling (before spontaneously breaking its symmetry). The introduced scalar isoscalar might be a resonant source for the diphoton excess of 750 GeV, suggested recently by experiment.
Free energy and hidden barriers of the β-sheet structure of prion protein.
Paz, S Alexis; Abrams, Cameron F
2015-10-13
On-the-fly free-energy parametrization is a new collective variable biasing approach akin to metadynamics with one important distinction: rather than acquiring an accelerated distribution via a history-dependent bias potential, sampling on this distribution is achieved from the beginning of the simulation using temperature-accelerated molecular dynamics. In the present work, we compare the performance of both approaches to compute the free-energy profile along a scalar collective variable measuring the H-bond registry of the β-sheet structure of the mouse Prion protein. Both methods agree on the location of the free-energy minimum, but free-energy profiles from well-tempered metadynamics are subject to a much higher degree of statistical noise due to hidden barriers. The sensitivity of metadynamics to hidden barriers is shown to be a consequence of the history dependence of the bias potential, and we detail the nature of these barriers for the prion β-sheet. In contrast, on-the-fly parametrization is much less sensitive to these barriers and thus displays improved convergence behavior relative to that of metadynamics. While hidden barriers are a frequent and central issue in free-energy methods, on-the-fly free-energy parametrization appears to be a robust and preferable method to confront this issue.
Ryabinkin, Ilya G
2016-01-01
An accurate description of nonadiabatic dynamics of molecular species on metallic surfaces poses a serious computational challenge associated with a multitude of closely-spaced electronic states. We propose a mixed quantum-classical scheme that addresses this challenge by introducing collective electronic variables. These variables are defined through analytic block-diagonalization applied to the time-dependent Hamiltonian matrix governing the electronic dynamics. We compare our scheme with the Ehrenfest approach and with a full-memory electronic friction model on a one-dimensional "adatom + atomic chain" model. Our simulations demonstrate that collective-mode dynamics with only few (2-3) electronic variables is robust and can describe a variety of situations: from a chemisorbed atom on an insulator to an atom on a metallic surface. Our molecular model also reveals that the friction approach is prone to unpredictable and catastrophic failures.
Short- and long-term variations in non-linear dynamics of heart rate variability
DEFF Research Database (Denmark)
Kanters, J K; Højgaard, M V; Agner, E;
1996-01-01
OBJECTIVES: The purpose of the study was to investigate the short- and long-term variations in the non-linear dynamics of heart rate variability, and to determine the relationships between conventional time and frequency domain methods and the newer non-linear methods of characterizing heart rate...... variability. METHODS: Twelve healthy subjects were investigated by 3-h ambulatory ECG recordings repeated on 3 separate days. Correlation dimension, non-linear predictability, mean heart rate, and heart rate variability in the time and frequency domains were measured and compared with the results from...... corresponding surrogate time series. RESULTS: A small significant amount of non-linear dynamics exists in heart rate variability. Correlation dimensions and non-linear predictability are relatively specific parameters for each individual examined. The correlation dimension is inversely correlated to the heart...
Slow dynamics and high variability in balanced cortical networks with clustered connections.
Litwin-Kumar, Ashok; Doiron, Brent
2012-11-01
Anatomical studies demonstrate that excitatory connections in cortex are not uniformly distributed across a network but instead exhibit clustering into groups of highly connected neurons. The implications of clustering for cortical activity are unclear. We studied the effect of clustered excitatory connections on the dynamics of neuronal networks that exhibited high spike time variability owing to a balance between excitation and inhibition. Even modest clustering substantially changed the behavior of these networks, introducing slow dynamics during which clusters of neurons transiently increased or decreased their firing rate. Consequently, neurons exhibited both fast spiking variability and slow firing rate fluctuations. A simplified model shows how stimuli bias networks toward particular activity states, thereby reducing firing rate variability as observed experimentally in many cortical areas. Our model thus relates cortical architecture to the reported variability in spontaneous and evoked spiking activity.
Connolly, Joseph W.; Friedlander, David; Kopasakis, George
2015-01-01
This paper covers the development of an integrated nonlinear dynamic simulation for a variable cycle turbofan engine and nozzle that can be integrated with an overall vehicle Aero-Propulso-Servo-Elastic (APSE) model. A previously developed variable cycle turbofan engine model is used for this study and is enhanced here to include variable guide vanes allowing for operation across the supersonic flight regime. The primary focus of this study is to improve the fidelity of the model's thrust response by replacing the simple choked flow equation convergent-divergent nozzle model with a MacCormack method based quasi-1D model. The dynamic response of the nozzle model using the MacCormack method is verified by comparing it against a model of the nozzle using the conservation element/solution element method. A methodology is also presented for the integration of the MacCormack nozzle model with the variable cycle engine.
Institute of Scientific and Technical Information of China (English)
赵丽娜; 刘作军; 苟斌; 杨鹏
2014-01-01
Effective pre-recognition of human gait is one of the key points to make the dynamic prosthetic knee joint coordinate with the body movement. Acceleration sensor installed in the prosthetic socket and pressure sensor installed in the plantar are used to acquire body’s motion information. According to regularity and repeatability characteristics, hidden Markov model is adopted to analyze the acquired motion information and performing gait pre-recognition. The experiments show that the gait pre-recognition of dynamic lower prosthesis based on hidden Markov model is effective and accurate.%为使动力型假肢膝关节协调配合人体的运动，关键是对人体行走步态进行有效预识别。本文利用安装在假肢接受腔上的加速度传感器和安装在足底的压力传感器采集人体的运动信息，根据人体运动的规律性和重复性特点，通过将隐马尔可夫模型引入到所获得的运动信息中来分析并预识别人体的运动步态。实验表明，基于隐马尔可夫模型的动力型下肢假肢的步态预识别方法是有效并且准确的。
Zhang, Yu-Lin
This paper states the application of state-space method to the analysis of the dynamic characteristics of a variable thrust liquid propellant rocket engine and presents a set of state equations for describing the dynamic process of the engine. An efficient numerical method for solving these system equations is developed. The theoretical solutions agree well with the experimental data. The analysis leads to the following conclusion: the set coefficient of the pulse width, the working frequency of the solenoid valves and the deviation of the critical working points of these valves are important parameters for determining the dynamic response time and the control precision of this engine. The methods developed in this paper may be used effectively in the analysis of dynamic characteristics of variable thrust liquid propellant rocket engines.
Senkel, Luise
2016-01-01
This edited book aims at presenting current research activities in the field of robust variable-structure systems. The scope equally comprises highlighting novel methodological aspects as well as presenting the use of variable-structure techniques in industrial applications including their efficient implementation on hardware for real-time control. The target audience primarily comprises research experts in the field of control theory and nonlinear dynamics but the book may also be beneficial for graduate students.
Dynamics Behavior Research on Variable Linear Vibration Screen with Flexible Screen Face
Changlong Du; Kuidong Gao; Jianping Li; Hao Jiang
2014-01-01
In order to enable the variable linear vibration screen with ideal movement behavior of screen surface and efficient screening capacity, five-freedom dynamic model and stability equations of the variable linear vibration screen were established based on power balance method and Hamilton principle. The motion behaviour of screen face was investigated, and − 0.10 m ≤ xf ≤ − 0.04 m was confirmed as the best range of exciting position. With analysis of stability equations, the stable requirement ...
Hidden Statistics Approach to Quantum Simulations
Zak, Michail
2010-01-01
Recent advances in quantum information theory have inspired an explosion of interest in new quantum algorithms for solving hard computational (quantum and non-quantum) problems. The basic principle of quantum computation is that the quantum properties can be used to represent structure data, and that quantum mechanisms can be devised and built to perform operations with this data. Three basic non-classical properties of quantum mechanics superposition, entanglement, and direct-product decomposability were main reasons for optimism about capabilities of quantum computers that promised simultaneous processing of large massifs of highly correlated data. Unfortunately, these advantages of quantum mechanics came with a high price. One major problem is keeping the components of the computer in a coherent state, as the slightest interaction with the external world would cause the system to decohere. That is why the hardware implementation of a quantum computer is still unsolved. The basic idea of this work is to create a new kind of dynamical system that would preserve the main three properties of quantum physics superposition, entanglement, and direct-product decomposability while allowing one to measure its state variables using classical methods. In other words, such a system would reinforce the advantages and minimize limitations of both quantum and classical aspects. Based upon a concept of hidden statistics, a new kind of dynamical system for simulation of Schroedinger equation is proposed. The system represents a modified Madelung version of Schroedinger equation. It preserves superposition, entanglement, and direct-product decomposability while allowing one to measure its state variables using classical methods. Such an optimal combination of characteristics is a perfect match for simulating quantum systems. The model includes a transitional component of quantum potential (that has been overlooked in previous treatment of the Madelung equation). The role of the
Duke, Jessica R; Ananth, Nandini
2015-11-05
Mapping variable ring polymer molecular dynamics (MV-RPMD) is an approximate quantum dynamics method based on imaginary-time path integrals for simulating electronically nonadiabatic photochemical processes. By employing a mapping protocol to transform from a discrete electronic state basis to continuous Cartesian phase-space variables, the method captures electronic state transitions coupled to nuclear motion using only classical MD trajectories. In this work, we extend the applicability of MV-RPMD to simulations of photoinduced excited electronic state dynamics in nonadiabatic systems with multiple avoided crossings. We achieve this by deriving a new electronic state population estimator in the phase space of electronic variables that is exact at equilibrium and numerically accurate in real time. Further, we introduce an efficient constraint protocol to initialize an MV-RPMD simulation to a particular electronic state. We numerically demonstrate the accuracy of this estimator and constraint technique in describing electronic state dynamics from an initial nonequilibrium state in six model systems, three of which describe photodissociation.
Deng, Chenhui; Plan, Elodie L; Karlsson, Mats O
2016-06-01
Parameter variation in pharmacometric analysis studies can be characterized as within subject parameter variability (WSV) in pharmacometric models. WSV has previously been successfully modeled using inter-occasion variability (IOV), but also stochastic differential equations (SDEs). In this study, two approaches, dynamic inter-occasion variability (dIOV) and adapted stochastic differential equations, were proposed to investigate WSV in pharmacometric count data analysis. These approaches were applied to published count models for seizure counts and Likert pain scores. Both approaches improved the model fits significantly. In addition, stochastic simulation and estimation were used to explore further the capability of the two approaches to diagnose and improve models where existing WSV is not recognized. The results of simulations confirmed the gain in introducing WSV as dIOV and SDEs when parameters vary randomly over time. Further, the approaches were also informative as diagnostics of model misspecification, when parameters changed systematically over time but this was not recognized in the structural model. The proposed approaches in this study offer strategies to characterize WSV and are not restricted to count data.
Long-term successional forest dynamics: species and community responses to climatic variability
Energy Technology Data Exchange (ETDEWEB)
Kardol, Paul [ORNL; Todd Jr, Donald E [ORNL; Hanson, Paul J [ORNL; Mulholland, Patrick J [ORNL
2010-01-01
Question: Are tree dynamics sensitive to climatic variability, and do tree species differ in their responses to climatic variability? Hence, is vulnerability of forest communities to climatic variability depending on stand composition? Location: Mixed young forest at Walker Branch Watershed near Oak Ridge, East-Tennessee, USA. Methods: Using a long-term data set (1967-2006), we analyzed temporal forest dynamics at the tree and species level, and we analyzed community dynamics for forest stands that different in their initial species composition (i.e., Chestnut Oak, Oak-Hickory, Pine, and Yellow poplar stands). Using summer drought and growing season temperature as defined climate drivers, we evaluated relationships between forest dynamics and climate across levels of organization. Results: Over the 4-decade studied period, forest communities underwent successional change and substantially increased their biomass. Variation in summer drought and growing season temperature contributed to temporal biomass dynamics for some tree species, but not for others. Stand-level responses to climatic variability were shown to be related to responses of specific component species; however, not for Pine stands. Pinus echinata, the dominant species in stands initially identified as Pine stands, decreased over time due to periodical outbreaks of the pine bark beetle (Dendroctonus frontalis). The outbreaks on Walker Branch could not be directly related to climatic conditions. Conclusions: Our results imply that vulnerability of developing forests to predicted climate conditions is stand-type dependent, and hence, is a function of species composition. Autogenic successional processes (or insect outbreaks) were found to prevail over climatic variability in determining long-term forest dynamics for stands dominated by sensitive species, emphasizing the importance of studying interactions between forest succession and climate change.
Estallo, Elizabet L; Ludueña-Almeida, Francisco F; Introini, María V; Zaidenberg, Mario; Almirón, Walter R
2015-01-01
This study aims to develop a forecasting model by assessing the weather variability associated with seasonal fluctuation of Aedes aegypti oviposition dynamic at a city level in Orán, in northwestern Argentina. Oviposition dynamics were assessed by weekly monitoring of 90 ovitraps in the urban area during 2005-2007. Correlations were performed between the number of eggs collected weekly and weather variables (rainfall, photoperiod, vapor pressure of water, temperature, and relative humidity) with and without time lags (1 to 6 weeks). A stepwise multiple linear regression analysis was performed with the set of meteorological variables from the first year of study with the variables in the time lags that best correlated with the oviposition. Model validation was conducted using the data from the second year of study (October 2006- 2007). Minimum temperature and rainfall were the most important variables. No eggs were found at temperatures below 10 °C. The most significant time lags were 3 weeks for minimum temperature and rains, 3 weeks for water vapor pressure, and 6 weeks for maximum temperature. Aedes aegypti could be expected in Orán three weeks after rains with adequate min temperatures. The best-fit forecasting model for the combined meteorological variables explained 70 % of the variance (adj. R(2)). The correlation between Ae. aegypti oviposition observed and estimated by the forecasting model resulted in rs = 0.80 (P variables, vector activity can be predicted three or four weeks in advance.
Operation ranges and dynamic capabilities of variable-speed pumped-storage hydropower
Mercier, Thomas; Olivier, Mathieu; Dejaeger, Emmanuel
2017-04-01
The development of renewable and intermittent power generation creates incentives for the development of both energy storage solutions and more flexible power generation assets. Pumped-storage hydropower (PSH) is the most established and mature energy storage technology, but recent developments in power electronics have created a renewed interest by providing PSH units with a variable-speed feature, thereby increasing their flexibility. This paper reviews technical considerations related to variable-speed PSH in link with the provision of primary frequency control, also referred to as frequency containment reserves (FCRs). Based on the detailed characteristics of a scale model pump-turbine, the variable-speed operation ranges in pump and turbine modes are precisely assessed and the implications for the provision of FCRs are highlighted. Modelling and control for power system studies are discussed, both for fixed- and variable-speed machines and simulation results are provided to illustrate the high dynamic capabilities of variable-speed PSH.
Human movement variability, nonlinear dynamics, and pathology: is there a connection?
Stergiou, Nicholas; Decker, Leslie M
2011-10-01
Fields studying movement generation, including robotics, psychology, cognitive science, and neuroscience utilize concepts and tools related to the pervasiveness of variability in biological systems. The concept of variability and the measures for nonlinear dynamics used to evaluate this concept open new vistas for research in movement dysfunction of many types. This review describes innovations in the exploration of variability and their potential importance in understanding human movement. Far from being a source of error, evidence supports the presence of an optimal state of variability for healthy and functional movement. This variability has a particular organization and is characterized by a chaotic structure. Deviations from this state can lead to biological systems that are either overly rigid and robotic or noisy and unstable. Both situations result in systems that are less adaptable to perturbations, such as those associated with unhealthy pathological states or absence of skillfulness.
Abramov, Rafail V
2011-01-01
Chaotic multiscale dynamical systems are common in many areas of science, one of the examples being the interaction of the slow climate dynamics with the fast turbulent weather dynamics. One of the key questions about chaotic multiscale systems is how the fast dynamics affects chaos at the slow variables, and, therefore, impacts uncertainty and predictability of the slow dynamics. Here we demonstrate that the linear slow-fast coupling with the total energy conservation property promotes the suppression of chaos at the slow variables through the rapid mixing at the fast variables, both theoretically and through numerical simulations. A suitable mathematical framework is developed, connecting the slow dynamics on the tangent subspaces to the infinite-time linear response of the mean state to a constant external forcing at the fast variables. Additionally, it is shown that the uncoupled dynamics for the slow variables may remain chaotic while the complete multiscale system loses chaos and becomes completely pred...
Environmental controls on the spatial variability of soil water dynamics in a small watershed
Hu, Wei; Chau, Henry Wai; Qiu, Weiwen; Si, Bingcheng
2017-08-01
Soil water content (SWC) in the root zone is controlled by a suite of environmental variables. Complication arises from the cross-correlation between these environmental variables. Therefore, there is still a poor understanding on the controls of root zone SWC dynamics due, in part, to a lack of an appropriate method to untangle the controls. The objective of this study was to reveal the dominant controls of root zone soil water dynamics in a small watershed using an appropriate method based on empirical orthogonal function (EOF). For this purpose, SWC of 0-0.8 m layer in a small watershed on the Chinese Loess Plateau was used. The space-variant temporal anomaly (Rtn) of SWC, which is responsible for the spatial variability of soil water dynamics, was decomposed using the EOF. Results indicated that 86% of the total variations of Rtn were explained by three significant spatial structures (EOFs). Sand content and grass yield dominated the EOF1 of Rtn and elevation and aspect dominated EOF2 and EOF3 of Rtn , respectively. Moreover, their effects on soil water dynamics were time-dependent. The EOF analysis showed that three independent groups of factors (i.e., soil and vegetation dominated earth surface condition, elevation related near surface air humidity, and aspect regulated energy input) may drive the variability in soil water dynamics. Traditional correlation analysis, however, indicated that SWC was greater at higher elevation and sun-facing slopes, which distorted the soil water dynamics controls. Although original SWC-based partial correlation basically supported our findings, the results highly depended on the controlling factors selected. This study implied that Rtn rather than original SWC should be preferred for understanding soil water dynamics controls.
Dynamic Variables of Science Classroom Discourse in Relation to Teachers' Instructional Beliefs
Kaya, Sibel
2014-01-01
The current study examines if the occurrence of dynamic variables namely, authentic questions, uptake, high-level evaluation and student questions in primary science classrooms vary by teachers' instructional beliefs. Twelve 4th grade teachers from two different schools volunteered to participate in the study. Data was collected through…
Dynamic Analysis of Fluid Power Drive-trains for Variable Speed Wind Turbines: a Parameter Study
Jarquin Laguna, A.; Diepeveen, N.F.B.
2013-01-01
In the pursuit of making wind energy technology more economically attractive, the application of fluid power technology for the transmission of wind energy is being developed by several parties all over the world. This paper presents a dynamic model of a fluid power transmission for variable speed w
Barbu, Viorel; Bonaccorsi, Stefano; Tubaro, Luciano
2015-01-01
This work is concerned with existence of weak solutions to discon- tinuous stochastic differential equations driven by multiplicative Gaus- sian noise and sliding mode control dynamics generated by stochastic differential equations with variable structure, that is with jump nonlin- earity. The treatment covers the finite dimensional stochastic systems and the stochastic diffusion equation with multiplicative noise.
Dynamic Analysis of Fluid Power Drive-trains for Variable Speed Wind Turbines: a Parameter Study
Jarquin Laguna, A.; Diepeveen, N.F.B.
2013-01-01
In the pursuit of making wind energy technology more economically attractive, the application of fluid power technology for the transmission of wind energy is being developed by several parties all over the world. This paper presents a dynamic model of a fluid power transmission for variable speed w
Properties of low-dimensional collective variables in the molecular dynamics of biopolymers
Meloni, Roberto; Camilloni, Carlo; Tiana, Guido
2016-11-01
The description of the dynamics of a complex, high-dimensional system in terms of a low-dimensional set of collective variables Y can be fruitful if the low-dimensional representation satisfies a Langevin equation with drift and diffusion coefficients that depend only on Y . We present a computational scheme to evaluate whether a given collective variable provides a faithful low-dimensional representation of the dynamics of a high-dimensional system. The scheme is based on the framework of a finite-difference Langevin equation, similar to that used for molecular-dynamics simulations. This allows one to calculate the drift and diffusion coefficients in any point of the full-dimensional system. The width of the distribution of drift and diffusion coefficients in an ensemble of microscopic points at the same value of Y indicates to what extent the dynamics of Y is described by a simple Langevin equation. Using a simple protein model, we show that collective variables often used to describe biopolymers display a non-negligible width both in the drift and in the diffusion coefficients. We also show that the associated effective force is compatible with the equilibrium free energy calculated from a microscopic sampling, but it results in markedly different dynamical properties.
Learning an intrinsic-variable preserving manifold for dynamic visual tracking.
Qiao, Hong; Zhang, Peng; Zhang, Bo; Zheng, Suiwu
2010-06-01
Manifold learning is a hot topic in the field of computer science, particularly since nonlinear dimensionality reduction based on manifold learning was proposed in Science in 2000. The work has achieved great success. The main purpose of current manifold-learning approaches is to search for independent intrinsic variables underlying high dimensional inputs which lie on a low dimensional manifold. In this paper, a new manifold is built up in the training step of the process, on which the input training samples are set to be close to each other if the values of their intrinsic variables are close to each other. Then, the process of dimensionality reduction is transformed into a procedure of preserving the continuity of the intrinsic variables. By utilizing the new manifold, the dynamic tracking of a human who can move and rotate freely is achieved. From the theoretical point of view, it is the first approach to transfer the manifold-learning framework to dynamic tracking. From the application point of view, a new and low dimensional feature for visual tracking is obtained and successfully applied to the real-time tracking of a free-moving object from a dynamic vision system. Experimental results from a dynamic tracking system which is mounted on a dynamic robot validate the effectiveness of the new algorithm.
Influence of forced respiration on nonlinear dynamics in heart rate variability
DEFF Research Database (Denmark)
Kanters, J K; Højgaard, M V; Agner, E;
1997-01-01
of this study was to test whether the known nonlinear input from spontaneous respiration is a source for the nonlinearities in heart rate variability. Twelve healthy subjects were examined in supine position with 3-h electrocardiogram recordings during both spontaneous and forced respiration in accordance...... expressed as the nonlinear prediction error did not differ between spontaneous respiration, 32.3 +/- 3.4 ms, and forced respiration, 31.9 +/- 5.7. It is concluded that the origin of the nonlinear dynamics in heart rate variability is not a nonlinear input from the respiration into the cardiovascular...... oscillator. Additional studies are needed to elucidate the mechanisms behind the nonlinear dynamics in heart rate variability....
Wang, Xin-Fan; Wang, Jian-Qiang; Deng, Sheng-Yue
2013-01-01
We investigate the dynamic stochastic multicriteria decision making (SMCDM) problems, in which the criterion values take the form of log-normally distributed random variables, and the argument information is collected from different periods. We propose two new geometric aggregation operators, such as the log-normal distribution weighted geometric (LNDWG) operator and the dynamic log-normal distribution weighted geometric (DLNDWG) operator, and develop a method for dynamic SMCDM with log-normally distributed random variables. This method uses the DLNDWG operator and the LNDWG operator to aggregate the log-normally distributed criterion values, utilizes the entropy model of Shannon to generate the time weight vector, and utilizes the expectation values and variances of log-normal distributions to rank the alternatives and select the best one. Finally, an example is given to illustrate the feasibility and effectiveness of this developed method.
Directory of Open Access Journals (Sweden)
Xin-Fan Wang
2013-01-01
Full Text Available We investigate the dynamic stochastic multicriteria decision making (SMCDM problems, in which the criterion values take the form of log-normally distributed random variables, and the argument information is collected from different periods. We propose two new geometric aggregation operators, such as the log-normal distribution weighted geometric (LNDWG operator and the dynamic log-normal distribution weighted geometric (DLNDWG operator, and develop a method for dynamic SMCDM with log-normally distributed random variables. This method uses the DLNDWG operator and the LNDWG operator to aggregate the log-normally distributed criterion values, utilizes the entropy model of Shannon to generate the time weight vector, and utilizes the expectation values and variances of log-normal distributions to rank the alternatives and select the best one. Finally, an example is given to illustrate the feasibility and effectiveness of this developed method.
Ananth, Nandini
2013-09-01
We introduce mapping-variable ring polymer molecular dynamics (MV-RPMD), a model dynamics for the direct simulation of multi-electron processes. An extension of the RPMD idea, this method is based on an exact, imaginary time path-integral representation of the quantum Boltzmann operator using continuous Cartesian variables for both electronic states and nuclear degrees of freedom. We demonstrate the accuracy of the MV-RPMD approach in calculations of real-time, thermal correlation functions for a range of two-state single-mode model systems with different coupling strengths and asymmetries. Further, we show that the ensemble of classical trajectories employed in these simulations preserves the Boltzmann distribution and provides a direct probe into real-time coupling between electronic state transitions and nuclear dynamics.
Self-similarity of complex networks and hidden metric spaces
Serrano, M Angeles; Boguna, Marian
2007-01-01
We demonstrate that the self-similarity of some scale-free networks with respect to a simple degree-thresholding renormalization scheme finds a natural interpretation in the assumption that network nodes exist in hidden metric spaces. Clustering, i.e., cycles of length three, plays a crucial role in this framework as a topological reflection of the triangle inequality in the hidden geometry. We prove that a class of hidden variable models with underlying metric spaces are able to accurately reproduce the self-similarity properties that we measured in the real networks. Our findings indicate that hidden geometries underlying these real networks are a plausible explanation for their observed topologies and, in particular, for their self-similarity with respect to the degree-based renormalization.
Hidden Local Symmetry and Beyond
Yamawaki, Koichi
2016-01-01
Gerry Brown was a godfather of our hidden local symmetry (HLS) for the vector meson from the birth of the theory throughout his life. The HLS is originated from very nature of the nonlinear realization of the symmetry G based on the manifold G/H, and thus is universal to any physics based on the nonlinear realization. Here I focus on the Higgs Lagrangian of the Standard Model (SM), which is shown to be equivalent to the nonlinear sigma model based on G/H= SU(2)_L x SU(2)_R/SU(2)_V with additional symmetry, the nonlinearly realized scale symmetry. Then the SM does have a dynamical gauge boson of the SU(2)_V HLS, "SM rho meson", in addition to the Higgs as a pseudo dilaton as well as the NG bosons to be absorbed into the W and Z. Based on the recent work done with S. Matsuzaki and H. Ohki, I discuss a novel possibility that the SM rho meson acquires kinetic term by the SM dynamics itself, which then stabilizes the skyrmion dormant in the SM as a viable candidate for the dark matter, what we call "Dark SM skyrmi...
Hidden local symmetry and beyond
Yamawaki, Koichi
Gerry Brown was a godfather of our hidden local symmetry (HLS) for the vector meson from the birth of the theory throughout his life. The HLS is originated from very nature of the nonlinear realization of the symmetry G based on the manifold G/H, and thus is universal to any physics based on the nonlinear realization. Here, I focus on the Higgs Lagrangian of the Standard Model (SM), which is shown to be equivalent to the nonlinear sigma model based on G/H = SU(2)L × SU(2)R/SU(2)V with additional symmetry, the nonlinearly-realized scale symmetry. Then, the SM does have a dynamical gauge boson of the SU(2)V HLS, "SM ρ meson", in addition to the Higgs as a pseudo-dilaton as well as the NG bosons to be absorbed in to the W and Z. Based on the recent work done with Matsuzaki and Ohki, I discuss a novel possibility that the SM ρ meson acquires kinetic term by the SM dynamics itself, which then stabilizes the skyrmion dormant in the SM as a viable candidate for the dark matter, what we call "dark SM skyrmion (DSMS)".
Multistability and hidden attractors in a relay system with hysteresis
DEFF Research Database (Denmark)
Zhusubaliyev, Zhanybai T.; Mosekilde, Erik; Rubanov, Vasily G.
2015-01-01
For nonlinear dynamic systems with switching control, the concept of a "hidden attractor" naturally applies to a stable dynamic state that either (1) coexists with the stable switching cycle or (2), if the switching cycle is unstable, has a basin of attraction that does not intersect with the nei...
Binary hidden Markov models and varieties
Critch, Andrew J
2012-01-01
The technological applications of hidden Markov models have been extremely diverse and successful, including natural language processing, gesture recognition, gene sequencing, and Kalman filtering of physical measurements. HMMs are highly non-linear statistical models, and just as linear models are amenable to linear algebraic techniques, non-linear models are amenable to commutative algebra and algebraic geometry. This paper examines closely those HMMs in which all the random variables, called nodes, are binary. Its main contributions are (1) minimal defining equations for the 4-node model, comprising 21 quadrics and 29 cubics, which were computed using Gr\\"obner bases in the cumulant coordinates of Sturmfels and Zwiernik, and (2) a birational parametrization for every binary HMM, with an explicit inverse for recovering the hidden parameters in terms of observables. The new model parameters in (2) are hence rationally identifiable in the sense of Sullivant, Garcia-Puente, and Spielvogel, and each model's Zar...
Estallo, Elizabet L.; Ludueña-Almeida, Francisco F.; Introini, María V.; Zaidenberg, Mario; Almirón, Walter R.
2015-01-01
This study aims to develop a forecasting model by assessing the weather variability associated with seasonal fluctuation of Aedes aegypti oviposition dynamic at a city level in Orán, in northwestern Argentina. Oviposition dynamics were assessed by weekly monitoring of 90 ovitraps in the urban area during 2005-2007. Correlations were performed between the number of eggs collected weekly and weather variables (rainfall, photoperiod, vapor pressure of water, temperature, and relative humidity) with and without time lags (1 to 6 weeks). A stepwise multiple linear regression analysis was performed with the set of meteorological variables from the first year of study with the variables in the time lags that best correlated with the oviposition. Model validation was conducted using the data from the second year of study (October 2006- 2007). Minimum temperature and rainfall were the most important variables. No eggs were found at temperatures below 10°C. The most significant time lags were 3 weeks for minimum temperature and rains, 3 weeks for water vapor pressure, and 6 weeks for maximum temperature. Aedes aegypti could be expected in Orán three weeks after rains with adequate min temperatures. The best-fit forecasting model for the combined meteorological variables explained 70 % of the variance (adj. R2). The correlation between Ae. aegypti oviposition observed and estimated by the forecasting model resulted in rs = 0.80 (P vector activity can be predicted three or four weeks in advance. PMID:25993415
Gas-dynamic Variable Relation on Opposite Sides of the Gas-dynamic Discontinuity
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Pavel Viktorovich Bulat
2015-04-01
Full Text Available The goal of this study is to study the conditions of dynamic compatibility on gas-dynamic discontinuities written in the form of a generalized adiabat. We have considered the basic concepts of the gas-dynamic discontinuity theory, the ratios permitting to calculate pressure shocks. Recommendations for rational problem definition and methods of solution of the typical computational problems are given. The dependences for calculation of parameters behind the shock according to the known parameters of a stream and the shock intensity recorded for the first time with the help of a generalized adiabatic line are considered. Substituting in these relations equations of adiabatic line of Laplace-Poisson, Rankine-Hugoniot and Chapman-Jouget, you can calculate the parameters behind, accordingly: simple waves, shockwaves and detonation waves. There are given in friendly graphic form the dependence on the Mach number of incoming flow and gas adiabatic index of the most relevant parameters of shocks: maximum intensity, stream deviation angle on the shock, critical angle of the stream deviation, shock angle according to the critical angle of a the stream deviation. The work can be recommended to the experts, engineers and scientists working in the field of aerospace engineering, metallurgy and metal hardening, for usage of control technologies for hypersonic currents containing gas-dynamic discontinuity.
Can we identify non-stationary dynamics of trial-to-trial variability?
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Emili Balaguer-Ballester
Full Text Available Identifying sources of the apparent variability in non-stationary scenarios is a fundamental problem in many biological data analysis settings. For instance, neurophysiological responses to the same task often vary from each repetition of the same experiment (trial to the next. The origin and functional role of this observed variability is one of the fundamental questions in neuroscience. The nature of such trial-to-trial dynamics however remains largely elusive to current data analysis approaches. A range of strategies have been proposed in modalities such as electro-encephalography but gaining a fundamental insight into latent sources of trial-to-trial variability in neural recordings is still a major challenge. In this paper, we present a proof-of-concept study to the analysis of trial-to-trial variability dynamics founded on non-autonomous dynamical systems. At this initial stage, we evaluate the capacity of a simple statistic based on the behaviour of trajectories in classification settings, the trajectory coherence, in order to identify trial-to-trial dynamics. First, we derive the conditions leading to observable changes in datasets generated by a compact dynamical system (the Duffing equation. This canonical system plays the role of a ubiquitous model of non-stationary supervised classification problems. Second, we estimate the coherence of class-trajectories in empirically reconstructed space of system states. We show how this analysis can discern variations attributable to non-autonomous deterministic processes from stochastic fluctuations. The analyses are benchmarked using simulated and two different real datasets which have been shown to exhibit attractor dynamics. As an illustrative example, we focused on the analysis of the rat's frontal cortex ensemble dynamics during a decision-making task. Results suggest that, in line with recent hypotheses, rather than internal noise, it is the deterministic trend which most likely underlies
Dynamical and biogeochemical control on the decadal variability of ocean carbon fluxes
Directory of Open Access Journals (Sweden)
R. Séférian
2013-04-01
Full Text Available Several recent observation-based studies suggest that ocean anthropogenic carbon uptake has slowed down due to the impact of anthropogenic forced climate change. However, it remains unclear whether detected changes over the recent time period can be attributed to anthropogenic climate change or rather to natural climate variability (internal plus naturally forced variability alone. One large uncertainty arises from the lack of knowledge on ocean carbon flux natural variability at the decadal time scales. To gain more insights into decadal time scales, we have examined the internal variability of ocean carbon fluxes in a 1000 yr long preindustrial simulation performed with the Earth System Model IPSL-CM5A-LR. Our analysis shows that ocean carbon fluxes exhibit low-frequency oscillations that emerge from their year-to-year variability in the North Atlantic, the North Pacific, and the Southern Ocean. In our model, a 20 yr mode of variability in the North Atlantic air-sea carbon flux is driven by sea surface temperature variability and accounts for ~40% of the interannual regional variance. The North Pacific and the Southern Ocean carbon fluxes are also characterised by decadal to multi-decadal modes of variability (10 to 50 yr that account for 20–40% of the interannual regional variance. These modes are driven by the vertical supply of dissolved inorganic carbon through the variability of Ekman-induced upwelling and deep-mixing events. Differences in drivers of regional modes of variability stem from the coupling between ocean dynamics variability and the ocean carbon distribution, which is set by large-scale secular ocean circulation.
Hydrologic variability in dryland regions: impacts on ecosystem dynamics and food security.
D'Odorico, Paolo; Bhattachan, Abinash
2012-11-19
Research on ecosystem and societal response to global environmental change typically considers the effects of shifts in mean climate conditions. There is, however, some evidence of ongoing changes also in the variance of hydrologic and climate fluctuations. A relatively high interannual variability is a distinctive feature of the hydrologic regime of dryland regions, particularly at the desert margins. Hydrologic variability has an important impact on ecosystem dynamics, food security and societal reliance on ecosystem services in water-limited environments. Here, we investigate some of the current patterns of hydrologic variability in drylands around the world and review the major effects of hydrologic fluctuations on ecosystem resilience, maintenance of biodiversity and food security. We show that random hydrologic fluctuations may enhance the resilience of dryland ecosystems by obliterating bistable deterministic behaviours and threshold-like responses to external drivers. Moreover, by increasing biodiversity and the associated ecosystem redundancy, hydrologic variability can indirectly enhance post-disturbance recovery, i.e. ecosystem resilience.
Variable Displacement Control of the Concrete Pumping System Based on Dynamic Programming
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Ye Min
2017-01-01
Full Text Available To solve the problems of cylinder piston striking cylinder and the hydraulic shocking of the main pump, and causing energy waste problem, the method of variable displacement control of piston stroke was proposed. In order to achieve effective control of the piston stroke, variable displacement control model was established under the physical constraint condition of non-collision between piston and cylinder. And the control process was realized by Dynamic Programming(DP, the simulation and test results show that piston of concrete pumping system don’t strike cylinder and reduce the hydraulic shock of the main pump outlet, meanwhile improve the response speed of the cylinder and achieve energy-saving purposes under varying loads. This control model built in the integration design space of structure variable and control variable is of guiding significance for solving open-loop system’s engineering problems.
Capturing the dynamics of response variability in the brain in ADHD
Directory of Open Access Journals (Sweden)
Janna van Belle
2015-01-01
Full Text Available ADHD is characterized by increased intra-individual variability in response times during the performance of cognitive tasks. However, little is known about developmental changes in intra-individual variability, and how these changes relate to cognitive performance. Twenty subjects with ADHD aged 7–24 years and 20 age-matched, typically developing controls participated in an fMRI-scan while they performed a go-no-go task. We fit an ex-Gaussian distribution on the response distribution to objectively separate extremely slow responses, related to lapses of attention, from variability on fast responses. We assessed developmental changes in these intra-individual variability measures, and investigated their relation to no-go performance. Results show that the ex-Gaussian measures were better predictors of no-go performance than traditional measures of reaction time. Furthermore, we found between-group differences in the change in ex-Gaussian parameters with age, and their relation to task performance: subjects with ADHD showed age-related decreases in their variability on fast responses (sigma, but not in lapses of attention (tau, whereas control subjects showed a decrease in both measures of variability. For control subjects, but not subjects with ADHD, this age-related reduction in variability was predictive of task performance. This group difference was reflected in neural activation: for typically developing subjects, the age-related decrease in intra-individual variability on fast responses (sigma predicted activity in the dorsal anterior cingulate gyrus (dACG, whereas for subjects with ADHD, activity in this region was related to improved no-go performance with age, but not to intra-individual variability. These data show that using more sophisticated measures of intra-individual variability allows the capturing of the dynamics of task performance and associated neural changes not permitted by more traditional measures.
An agent-based model of cellular dynamics and circadian variability in human endotoxemia.
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Tung T Nguyen
Full Text Available As cellular variability and circadian rhythmicity play critical roles in immune and inflammatory responses, we present in this study an agent-based model of human endotoxemia to examine the interplay between circadian controls, cellular variability and stochastic dynamics of inflammatory cytokines. The model is qualitatively validated by its ability to reproduce circadian dynamics of inflammatory mediators and critical inflammatory responses after endotoxin administration in vivo. Novel computational concepts are proposed to characterize the cellular variability and synchronization of inflammatory cytokines in a population of heterogeneous leukocytes. Our results suggest that there is a decrease in cell-to-cell variability of inflammatory cytokines while their synchronization is increased after endotoxin challenge. Model parameters that are responsible for IκB production stimulated by NFκB activation and for the production of anti-inflammatory cytokines have large impacts on system behaviors. Additionally, examining time-dependent systemic responses revealed that the system is least vulnerable to endotoxin in the early morning and most vulnerable around midnight. Although much remains to be explored, proposed computational concepts and the model we have pioneered will provide important insights for future investigations and extensions, especially for single-cell studies to discover how cellular variability contributes to clinical implications.
Institute of Scientific and Technical Information of China (English)
Qian Yong-Fen; Li Ren-Jie; Zhao Shu-Hong
2004-01-01
Using a form invariance under special infinitesimal transformations in which time is not variable, the non-Noether conserved quantity of the nonholonomic Vacco dynamical system with variable mass is studied. The differential equations of motion of the systems are established. The definition and criterion of the form invariance of the system under special infinitesimal transformations are studied. The necessary and sufficient condition under which the form invariance is a Lie symmetry is given. The Hojman theorem is established. Finally an example is given to illustrate the application of the result.
Directory of Open Access Journals (Sweden)
Lei Wang
2017-01-01
Full Text Available In real-world manufacturing systems, production scheduling systems are often implemented under random or dynamic events like machine failure, unexpected processing times, stochastic arrival of the urgent orders, cancellation of the orders, and so on. These dynamic events will lead the initial scheduling scheme to be nonoptimal and/or infeasible. Hence, appropriate dynamic rescheduling approaches are needed to overcome the dynamic events. In this paper, we propose a dynamic rescheduling method based on variable interval rescheduling strategy (VIRS to deal with the dynamic flexible job shop scheduling problem considering machine failure, urgent job arrival, and job damage as disruptions. On the other hand, an improved genetic algorithm (GA is proposed for minimizing makespan. In our improved GA, a mix of random initialization population by combining initialization machine and initialization operation with random initialization is designed for generating high-quality initial population. In addition, the elitist strategy (ES and improved population diversity strategy (IPDS are used to avoid falling into the local optimal solution. Experimental results for static and several dynamic events in the FJSP show that our method is feasible and effective.
Directory of Open Access Journals (Sweden)
Mike D.R. Zhang
2001-01-01
Full Text Available In this paper, a method for analyzing the dynamic response of a structural system with variable mass, damping and stiffness is first presented. The dynamic equations of the structural system with variable mass and stiffness are derived according to the whole working process of a bridge bucket unloader. At the end of the paper, an engineering numerical example is given.
Dynamic analysis of coupled vehicle-bridge system with uniformly variable speed
Wei-zhen, Li; Chang-ping, Chen; Yi-qi, Mao; Chang-zhao, Qian
2016-09-01
In this paper, a planar biaxial vehicle model with four degrees of freedom is presented based on spring-damping-mass system theory. By using Runge-Kutta method, the dynamic characteristics of a simply support bridge acting by moving vehicle with uniform variable speed are analyzed, and the effects of inertia force, relative acceleration and initial velocity are taken into consideration in the present research. The time-deflection response curves of the bridge under the variation of initial speed and acceleration are analyzed. Some valuable results are found which can provide a theoretical direction for the consideration of dynamical characteristics in design of bridge system.
Ireland, M J; Wood, P R
2008-01-01
We describe the Cool Opacity-sampling Dynamic EXtended (CODEX) atmosphere models of Mira variable stars, and examine in detail the physical and numerical approximations that go in to the model creation. The CODEX atmospheric models are obtained by computing the temperature and the chemical and radiative states of the atmospheric layers, assuming gas pressure and velocity profiles from Mira pulsation models, which extend from near the H-burning shell to the outer layers of the atmosphere. Although the code uses the approximation of Local Thermodynamic Equilibrium (LTE) and a grey approximation in the dynamical atmosphere code, many key observable quantities, such as infrared diameters and low-resolution spectra, are predicted robustly in spite of these approximations. We show that in visible light, radiation from Mira variables is dominated by fluorescence scattering processes, and that the LTE approximation likely under-predicts visible-band fluxes by a factor of two.
Institute of Scientific and Technical Information of China (English)
闫军
2016-01-01
Electromechanical dynamics analysis and simulation on a rollforming equipment with both sides variable cross-section are discussed in this study.The system includes mechanical parts and electro-magnetism parts, and it is a strongly coupled electromechanical system.Based on a virtual work principle and given power,generalized forces of this system are obtained.By using Lagrange-Maxwell equations, a model of electromechanical dynamics is established.Differential equations of two-phase winding on d-q axis are obtained by Park transformation, which comes from three-phase winding equations on the A-B-C axis.This system is solved with the 4th order Runge-Kutta’ s method, and discrete solutions of all variables are obtained.Finally, by using Matlab language, the system is simulated.The results show that the proposed method works very well.
Rule, Michael E; Vargas-Irwin, Carlos; Donoghue, John P; Truccolo, Wilson
2015-01-01
Understanding the sources of variability in single-neuron spiking responses is an important open problem for the theory of neural coding. This variability is thought to result primarily from spontaneous collective dynamics in neuronal networks. Here, we investigate how well collective dynamics reflected in motor cortex local field potentials (LFPs) can account for spiking variability during motor behavior. Neural activity was recorded via microelectrode arrays implanted in ventral and dorsal premotor and primary motor cortices of non-human primates performing naturalistic 3-D reaching and grasping actions. Point process models were used to quantify how well LFP features accounted for spiking variability not explained by the measured 3-D reach and grasp kinematics. LFP features included the instantaneous magnitude, phase and analytic-signal components of narrow band-pass filtered (δ,θ,α,β) LFPs, and analytic signal and amplitude envelope features in higher-frequency bands. Multiband LFP features predicted single-neuron spiking (1ms resolution) with substantial accuracy as assessed via ROC analysis. Notably, however, models including both LFP and kinematics features displayed marginal improvement over kinematics-only models. Furthermore, the small predictive information added by LFP features to kinematic models was redundant to information available in fast-timescale (<100 ms) spiking history. Overall, information in multiband LFP features, although predictive of single-neuron spiking during movement execution, was redundant to information available in movement parameters and spiking history. Our findings suggest that, during movement execution, collective dynamics reflected in motor cortex LFPs primarily relate to sensorimotor processes directly controlling movement output, adding little explanatory power to variability not accounted by movement parameters.
Directory of Open Access Journals (Sweden)
Michael Everett Rule
2015-06-01
Full Text Available Understanding the sources of variability in single-neuron spiking responses is an important open problem for the theory of neural coding. This variability is thought to result primarily from spontaneous collective dynamics in neuronal networks. Here, we investigate how well collective dynamics reflected in motor cortex local field potentials (LFPs can account for spiking variability during motor behavior. Neural activity was recorded via microelectrode arrays implanted in ventral and dorsal premotor and primary motor cortices of non-human primates performing naturalistic 3-D reaching and grasping actions. Point process models were used to quantify how well LFP features accounted for spiking variability not explained by the measured 3-D reach and grasp kinematics. LFP features included the instantaneous magnitude, phase and analytic-signal components of narrow band-pass filtered (δ, θ, α, β LFPs, and analytic signal and amplitude envelope features in higher-frequency bands. Multiband LFP features predicted single-neuron spiking (1ms resolution with substantial accuracy as assessed via ROC analysis. Notably, however, models including both LFP and kinematics features displayed marginal improvement over kinematics-only models. Furthermore, the small predictive information added by LFP features to kinematic models was redundant to information available in fast-timescale (<100ms spiking history. Overall, information in multiband LFP features, although predictive of single-neuron spiking during movement execution, was redundant to information available in movement parameters and spiking history. Our findings suggest that, during movement execution, collective dynamics reflected in motor cortex LFPs primarily relate to sensorimotor processes directly controlling movement output, adding little explanatory power to variability not accounted by movement parameters.
Dynamics Behavior Research on Variable Linear Vibration Screen with Flexible Screen Face
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Changlong Du
2014-08-01
Full Text Available In order to enable the variable linear vibration screen with ideal movement behavior of screen surface and efficient screening capacity, five-freedom dynamic model and stability equations of the variable linear vibration screen were established based on power balance method and Hamilton principle. The motion behaviour of screen face was investigated, and − 0.10 m ≤ xf ≤ − 0.04 m was confirmed as the best range of exciting position. With analysis of stability equations, the stable requirement of vibration screen was obtained: the direction angle of exciting force should be 0 ≤ θ ≤ 45°. Screening processes of variable linear vibration screen with flexible screen face, variable linear vibration screen with fixed screen face and linear vibration screen were investigated and compared by numerical simulation method, the results show that variable linear vibration screen with flexible screen face have such characteristics as higher intensity of projection and efficient screening. The correctness of theoretical research and simulation research were verified through experiment, and all of the work would provide some guidance for designing and studying variable linear vibration screen with flexible screen face.
Breeding site heterogeneity reduces variability in frog recruitment and population dynamics
McCaffery, Rebecca M.; Eby, Lisa A.; Maxell, Bryce A.; Corn, Paul Stephen
2013-01-01
Environmental stochasticity can have profound effects on the dynamics and viability of wild populations, and habitat heterogeneity provides one mechanism by which populations may be buffered against the negative effects of environmental fluctuations. Heterogeneity in breeding pond hydroperiod across the landscape may allow amphibian populations to persist despite variable interannual precipitation. We examined recruitment dynamics over 10 yr in a high-elevation Columbia spotted frog (Rana luteiventris) population that breeds in ponds with a variety of hydroperiods. We combined these data with matrix population models to quantify the consequences of heterogeneity in pond hydroperiod on net recruitment (i.e. number of metamorphs produced) and population growth rates. We compared our heterogeneous system to hypothetical homogeneous environments with only ephemeral ponds, only semi-permanent ponds, and only permanent ponds. We also examined the effects of breeding pond habitat loss on population growth rates. Most eggs were laid in permanent ponds each year, but survival to metamorphosis was highest in the semi-permanent ponds. Recruitment success varied by both year and pond type. Net recruitment and stochastic population growth rate were highest under a scenario with homogeneous semi-permanent ponds, but variability in recruitment was lowest in the scenario with the observed heterogeneity in hydroperiods. Loss of pond habitat decreased population growth rate, with greater decreases associated with loss of permanent and semi-permanent habitat. The presence of a diversity of pond hydroperiods on the landscape will influence population dynamics, including reducing variability in recruitment in an uncertain climatic future.
Managing Hidden Costs of Offshoring
DEFF Research Database (Denmark)
Larsen, Marcus M.; Pedersen, Torben
2014-01-01
This chapter investigates the concept of the ‘hidden costs’ of offshoring, i.e. unexpected offshoring costs exceeding the initially expected costs. Due to the highly undefined nature of these costs, we position our analysis towards the strategic responses of firms’ realisation of hidden costs....... In this regard, we argue that a major response to the hidden costs of offshoring is the identification and utilisation of strategic mechanisms in the organisational design to eventually achieving system integration in a globally dispersed and disaggregated organisation. This is heavily moderated by a learning...
Measurement of heart rate variability by methods based on nonlinear dynamics.
Huikuri, Heikki V; Mäkikallio, Timo H; Perkiömäki, Juha
2003-01-01
Heart rate (HR) variability has been conventionally analyzed with time and frequency domain methods, which measure the overall magnitude of R-R interval fluctuations around its mean value or the magnitude of fluctuations in some predetermined frequencies. Analysis of HR dynamics by methods based on chaos theory and nonlinear system theory has gained recent interest. This interest is based on observations suggesting that the mechanisms involved in cardiovascular regulation likely interact with each other in a nonlinear way. Furthermore, recent observational studies suggest that some indexes describing nonlinear HR dynamics, such as fractal scaling exponents, may provide more powerful prognostic information than the traditional HR variability indexes. In particular, short-term fractal scaling exponent measured by detrended fluctuation analysis method has been shown to predict fatal cardiovascular events in various populations. Approximate entropy, a nonlinear index of HR dynamics, which describes the complexity of R-R interval behavior, has provided information on the vulnerability to atrial fibrillation. There are many other nonlinear indexes, eg, Lyapunov exponent and correlation dimensions, which also give information on the characteristics of HR dynamics, but their clinical utility is not well established. Although concepts of chaos theory, fractal mathematics, and complexity measures of HR behavior in relation to cardiovascular physiology or various cardiovascular events are still far away from clinical medicine, they are a fruitful area for future research to expand our knowledge concerning the behavior of cardiovascular oscillations in normal healthy conditions as well as in disease states.
Transients drive the demographic dynamics of plant populations in variable environments
DEFF Research Database (Denmark)
McDonald, Jenni L; Stott, Iain; Townley, Stuart;
2016-01-01
clear patterns related to growth form. We find a surprising tendency for plant populations to boom rather than bust in response to temporal changes in vital rates and that stochastic growth rates increase with increasing tendency to boom. Synthesis. Transient dynamics contribute significantly......The dynamics of structured plant populations in variable environments can be decomposed into the ‘asymptotic’ growth contributed by vital rates, and ‘transient’ growth caused by deviation from stable stage structure. We apply this framework to a large, global data base of longitudinal studies...... of projection matrix models for plant populations. We ask, what is the relative contribution of transient boom and bust to the dynamic trajectories of plant populations in stochastic environments? Is this contribution patterned by phylogeny, growth form or the number of life stages per population and per...
Maximum Simplified Dynamic Model of Grass Field Ecosystem With Two Variables
Institute of Scientific and Technical Information of China (English)
曾庆存; 卢佩生; 曾晓东
1994-01-01
Based on general consideration and analysis, a maximum simplified dynamic model of grass field ecosystem with a single species is developed. The model consists of two variables: grass biomass of grass field per unit area and soil wetness, and is suitable for describing their mutual interaction. Other factors such as physical-chemical characteristics of soil, precipitation, irrigation, sunlight, temperature and consumers, are taken into account as parameters in the dynamical system. Qualitative analysis of the model shows that grass biomass of a possible ecological regime is determined by the stable equilibrium state of the dynamical system. For the grass species interacting weakly with soil wetness the grass biomass continuously depends on the precipitation. While, for a species interacting strongly with soil wetness, grass biomass is abundant if precipitation is larger than some critical value; otherwise, it becomes a desertification regime with very little or even zero grass biomass. The model also sh
Scale invariant extension of the standard model with a strongly interacting hidden sector.
Hur, Taeil; Ko, P
2011-04-08
We present a scale invariant extension of the standard model with a new QCD-like strong interaction in the hidden sector. A scale Λ(H) is dynamically generated in the hidden sector by dimensional transmutation, and chiral symmetry breaking occurs in the hidden sector. This scale is transmitted to the SM sector by a real singlet scalar messenger S and can trigger electroweak symmetry breaking. Thus all the mass scales in this model arise from the hidden sector scale Λ(H), which has quantum mechanical origin. Furthermore, the lightest hadrons in the hidden sector are stable by the flavor conservation of the hidden sector strong interaction, and could be the cold dark matter (CDM). We study collider phenomenology, relic density, and direct detection rates of the CDM of this model.
Vegetation dynamics and climate variability-associated biophysical process in West Africa
Song, G.; Xue, Y.; Cox, P. M.
2012-12-01
West Africa is a bioclimatic zone of predominantly annual grasses with shrubs and trees with a steep gradient in climate, soils, vegetation, fauna, land use and human utilization. West Africa ecosystem region suffered from the most severe and longest drought in the world during the Twentieth Century since the later 1960s. This study systematically investigates how climate variability and anomalies in West Africa affect the regional terrestrial ecosystem, including plant functional types' (PFT) spatial distribution and temporal variations and vegetation characteristics, through biophysical and photosynthesis processes at different scales. We use the offline Simplified Simple Biosphere Version 4/ Top-down Representation of Interactive Foliage and Flora Including Dynamics Model (SSiB4/TRIFFID), which is a fully coupled biophysical-dynamic vegetation (DVM) model to adequately incorporate the complex non-linear coupling dynamics between ecosystem and climate variability. The biophysical parameters in SSiB4 are adjusted with TRIFFID-produced vegetation parameter values, which ensure adequate biophysical process coupling. A 59-year simulation from 1948 was conducted using the meteorological forcing, which consists of substantial seasonal, interannual, and interdecal variability and long term dry trend. The results show that the simulated PFT's and leaf area index (LAI) correspond well to climate variability and are consistent with satellite derived vegetation conditions. The simulated inter-decadal variability in vegetation conditions is consistent with the Sahel drought in the 1970s and the 1980s and partial recovery in the 1990s and the 2000s (fig1). To further understand the biophysical mechanism of interactions of water, carbon, radiation, and vegetation dynamics, analyses are conducted to find relationships between vegetation variability and environmental conditions. It is found that the vegetation characteristics simulated by SSiB4/TRIFFID responds primarily to five
Zhao, Zhibiao
2011-06-01
We address the nonparametric model validation problem for hidden Markov models with partially observable variables and hidden states. We achieve this goal by constructing a nonparametric simultaneous confidence envelope for transition density function of the observable variables and checking whether the parametric density estimate is contained within such an envelope. Our specification test procedure is motivated by a functional connection between the transition density of the observable variables and the Markov transition kernel of the hidden states. Our approach is applicable for continuous time diffusion models, stochastic volatility models, nonlinear time series models, and models with market microstructure noise.
Hidden Markov Model for Stock Selection
Directory of Open Access Journals (Sweden)
Nguyet Nguyen
2015-10-01
Full Text Available The hidden Markov model (HMM is typically used to predict the hidden regimes of observation data. Therefore, this model finds applications in many different areas, such as speech recognition systems, computational molecular biology and financial market predictions. In this paper, we use HMM for stock selection. We first use HMM to make monthly regime predictions for the four macroeconomic variables: inflation (consumer price index (CPI, industrial production index (INDPRO, stock market index (S&P 500 and market volatility (VIX. At the end of each month, we calibrate HMM’s parameters for each of these economic variables and predict its regimes for the next month. We then look back into historical data to find the time periods for which the four variables had similar regimes with the forecasted regimes. Within those similar periods, we analyze all of the S&P 500 stocks to identify which stock characteristics have been well rewarded during the time periods and assign scores and corresponding weights for each of the stock characteristics. A composite score of each stock is calculated based on the scores and weights of its features. Based on this algorithm, we choose the 50 top ranking stocks to buy. We compare the performances of the portfolio with the benchmark index, S&P 500. With an initial investment of $100 in December 1999, over 15 years, in December 2014, our portfolio had an average gain per annum of 14.9% versus 2.3% for the S&P 500.
Scaling dimensions in hidden Kerr/CFT
Lowe, David A; Skanata, Antun
2011-01-01
It has been proposed that a hidden conformal field theory (CFT) governs the dynamics of low frequency scattering in a general Kerr black hole background. We further investigate this correspondence by mapping higher order corrections to the massless wave equations in a Kerr background to an expansion within the CFT in terms of higher dimension operators. This implies the presence of infinite towers of CFT primary operators with positive conformal dimensions compatible with unitarity. The exact Kerr background softly breaks the conformal symmetry and the scaling dimensions of these operators run with frequency. The scale-invariant fixed point is dual to a degenerate case of flat spacetime.
Senefeld, Jonathon; Yoon, Tejin; Hunter, Sandra K
2017-01-01
It is not known whether the age-related increase in fatigability of fast dynamic contractions in lower limb muscles also occurs in upper limb muscles. We compared age-related fatigability and variability of maximal-effort repeated dynamic contractions in the knee extensor and elbow flexor muscles; and determined associations between fatigability, variability of velocity between contractions and functional performance. 35 young (16 males; 21.0±2.6years) and 32 old (18 males; 71.3±6.2years) adults performed a dynamic fatiguing task involving 90 maximal-effort, fast, concentric, isotonic contractions (1 contraction/3s) with a load equivalent to 20% maximal voluntary isometric contraction (MVIC) torque with the elbow flexor and knee extensor muscles on separate days. Old adults also performed tests of balance and walking endurance. Old adults had greater fatigue-related reductions in peak velocity compared with young adults for both the elbow flexor and knee extensor muscles (P0.05). Old adults had greater variability of peak velocity during the knee extensor, but not during the elbow flexor fatiguing task. The age difference in fatigability was greater for the knee extensor muscles (35.9%) compared with elbow flexor muscles (9.7%, P<0.05). Less fatigability of the knee extensor muscles was associated with greater walking endurance (r=-0.34, P=0.048) and balance (r=-0.41, P=0.014) among old adults. An age-related increase in fatigability of a dynamic fatiguing task was greater for the knee extensor compared with the elbow flexor muscles in males and females, and greater fatigability was associated with lesser walking endurance and balance. Copyright © 2016 Elsevier Inc. All rights reserved.
Institute of Scientific and Technical Information of China (English)
Olivia MARTIUS; Cornelia SCHWIERZ; Michael SPRENGER
2008-01-01
This study presents a 44-year climatology of potential vorticity (PV) streamers in the Northern Hemi sphere based upon analyses of the ERA-40 reanalysis data set. A comparison to an existing 15-year clima tology yields very good agreement in the locations of PV streamer frequency maxima, but some differences are found in the amplitude of frequencies. The climatology is assessed with the focus on links between PV streamer frequencies and the synoptic- and planetary-scale variability of the dynamical tropopause. A comprehensive overview is provided on where (zonally) and when (seasonally) short-term variability throughout the extra-tropical and sub-tropical tropopause is enhanced or reduced. Several key processes that influence this variability are discussed. Baroclinic processes, for example, determine the variability in the storm-track areas in winter, whereas the Asian summer monsoon significantly influences the variability over Asia. The paper also describes links between the frequency of PV streamers in the extra-tropical and sub tropical tropopause and three major northern hemisphere teleconnection patterns. The observed changes in the PV streamer frequencies are closely related to concomitant variations of PV and its gradient within the tropopause region. During opposite phases of the North Atlantic Oscillation the location of the streamer frequency maxima shifts significantly in the Atlantic and European region in both the extra-tropics and subtropics. The influence of ENSO on the streamer frequencies is most pronounced in the subtropical Pacific.
Microgenetic analysis of hidden figures
Marković Slobodan S.; Gvozdenović Vasilije P.
2006-01-01
In this study the phenomenological and processual aspects of the perception of hidden figures were compared. The question was whether the more probable percepts of hidden figures, compared to the less probable percepts, were generated in earlier stages of the perceptual process. In the pilot study the subjects were asked to say what they see in a complex linear pattern. The three most frequent and the three least frequent perceptual descriptions were selected. In the experiment the microgenes...
Wang, Frédéric
2010-01-01
We give an overview of the Hidden Subgroup Problem (HSP) as of July 2010, including new results discovered since the survey of arXiv:quant-ph/0411037v1. We recall how the problem provides a framework for efficient quantum algorithms and present the standard methods based on coset sampling. We study the Dihedral and Symmetric HSPs and how they relate to hard problems on lattices and graphs. Finally, we conclude with the known solutions and techniques, describe connections with efficient algorithms as well as miscellaneous variants of HSP. We also bring various contributions to the topic. We show that in theory, we can solve HSP over a given group inductively: the base case is solving HSP over its simple factor groups and the inductive step is building efficient oracles over a normal subgroup N and over the factor group G/N. We apply this analysis to the Dedekindian HSP to get an alternative abelian HSP algorithm based on a change of the underlying group. We also propose a quotient reduction by the normal group...
Managing Hidden Costs of Offshoring
DEFF Research Database (Denmark)
Larsen, Marcus M.; Pedersen, Torben
2014-01-01
This chapter investigates the concept of the ‘hidden costs’ of offshoring, i.e. unexpected offshoring costs exceeding the initially expected costs. Due to the highly undefined nature of these costs, we position our analysis towards the strategic responses of firms’ realisation of hidden costs. In......-by-doing process, where hidden costs motivate firms and their employees to search for new and better knowledge on how to successfully manage the organisation. We illustrate this thesis based on the case of the LEGO Group.......This chapter investigates the concept of the ‘hidden costs’ of offshoring, i.e. unexpected offshoring costs exceeding the initially expected costs. Due to the highly undefined nature of these costs, we position our analysis towards the strategic responses of firms’ realisation of hidden costs....... In this regard, we argue that a major response to the hidden costs of offshoring is the identification and utilisation of strategic mechanisms in the organisational design to eventually achieving system integration in a globally dispersed and disaggregated organisation. This is heavily moderated by a learning...
The Hidden Costs of Offshoring
DEFF Research Database (Denmark)
Møller Larsen, Marcus; Manning, Stephan; Pedersen, Torben
2011-01-01
This study seeks to explain hidden costs of offshoring, i.e. unexpected costs resulting from the relocation of business tasks and activities outside the home country. We develop a model that highlights the role of complexity, design orientation and experience in explaining hidden costs of offshor...... of our study is to suggest how hidden costs of offshoring can be mitigated through an explicit orientation towards improving organizational processes and structures as well as experience with offshoring.......This study seeks to explain hidden costs of offshoring, i.e. unexpected costs resulting from the relocation of business tasks and activities outside the home country. We develop a model that highlights the role of complexity, design orientation and experience in explaining hidden costs...... of offshoring. Specifically, we propose that hidden costs can be explained by the combination of increasing structural, operational and social complexity of offshoring activities. In addition, we suggest that firm orientation towards organizational design as part of an offshoring strategy and offshoring...
Dynamic modeling of fixed-bed adsorption of flue gas using a variable mass transfer model
Energy Technology Data Exchange (ETDEWEB)
Park, Jehun; Lee, Jae W. [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)
2016-02-15
This study introduces a dynamic mass transfer model for the fixed-bed adsorption of a flue gas. The derivation of the variable mass transfer coefficient is based on pore diffusion theory and it is a function of effective porosity, temperature, and pressure as well as the adsorbate composition. Adsorption experiments were done at four different pressures (1.8, 5, 10 and 20 bars) and three different temperatures (30, 50 and 70 .deg. C) with zeolite 13X as the adsorbent. To explain the equilibrium adsorption capacity, the Langmuir-Freundlich isotherm model was adopted, and the parameters of the isotherm equation were fitted to the experimental data for a wide range of pressures and temperatures. Then, dynamic simulations were performed using the system equations for material and energy balance with the equilibrium adsorption isotherm data. The optimal mass transfer and heat transfer coefficients were determined after iterative calculations. As a result, the dynamic variable mass transfer model can estimate the adsorption rate for a wide range of concentrations and precisely simulate the fixed-bed adsorption process of a flue gas mixture of carbon dioxide and nitrogen.
Directory of Open Access Journals (Sweden)
Ataei A
2012-07-01
Full Text Available Mehrnoush Toufan,1 Babak Kazemi,1 Fariborz Akbarzadeh,1 Amin Ataei,1 Majid Khalili21Cardiovascular Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; 2Azerbaijan National Academy of Sciences, Baku, AzerbaijanBackground: Over the last two decades, morphological cardiac changes induced by athletic conditioning have been of great interest. Therefore, several studies have been orchestrated to delineate electrocardiography (ECG, echocardiography, and heart rate variability (HRV findings in athletes.Purpose: To assess the ECG, echocardiography, and HRV in a group of dynamic and static type athletes.Methods: Fifty professional athletes (20 static and 30 dynamic exercise athletes and 50 healthy nonathletes (control group were recruited. Standard 12-lead ECG and transthoracic echocardiography was performed on all athletes and the control group. Through echocardiography, variables including left ventricular (LV end-diastolic/systolic diameter, LV mass, and left atrial volume index were measured. In addition, both the athletes and the control group underwent ECG Holter monitoring for 15 minutes and several parameters related to HRV (time and frequency domain were recorded.Results: The most common ECG abnormalities among the athletes were sinus bradycardia and incomplete right bundle branch block. LV end-diastolic diameter and left atrial volume index were significantly greater in the dynamic athletes (P < 0.001. LV end-systolic diameter was significantly lower in the static group (P < 0.001. LV mass of the dynamic and static athletes was significantly greater than that of the controls (P < 0.001. Among the ECG Holter monitoring findings, the dynamic athletes had lower systolic blood pressure than the controls (P = 0.01. Heart rate was lowest in the control group (P < 0.001.Conclusion: The most common ECG abnormalities among adolescent Iranian athletes were sinus bradycardia and incomplete right bundle branch block. Static exercise seemed
Hidden symmetry of the quantum Calogero-Moser system
DEFF Research Database (Denmark)
Kuzentsov, Vadim b
1996-01-01
The hidden symmetry of the quantum Calogero-Moser system with an inverse-square potential is algebraically demonstrated making use of Dunkl's operators. We find the underlying algebra explaining the super-integrability phenomenon for this system. Applications to related multi-variable Bessel...
A novel design of hidden web crawler using ontology
Manvi; Bhatia, Komal Kumar; Dixit, Ashutosh
2015-01-01
Deep Web is content hidden behind HTML forms. Since it represents a large portion of the structured, unstructured and dynamic data on the Web, accessing Deep-Web content has been a long challenge for the database community. This paper describes a crawler for accessing Deep-Web using Ontologies. Performance evaluation of the proposed work showed that this new approach has promising results.
Kaminska, Ewa; Tarnacka, Magdalena; Madejczyk, Olga; Chrobok, Anna; Kaminski, Kamil; Paluch, Marian
2016-04-07
The molecular dynamics of three saccharides: D-glucose, 1,6-anhydro-D-glucose (levoglucosan) and 1,6:2,3-dianhydro-β-D-mannopyranose of various degrees of freedom, number of hydroxyl groups and internal structures was investigated over a wide range of temperatures and frequencies by means of Broadband Dielectric Spectroscopy (BDS). Despite the pronounced variety in the physicochemical properties of the carbohydrates, no change in the shape of the structural relaxation process was observed in the vicinity of the glass transition temperature (β(KWW) = 0.5). On the other hand further studies of the Debye-Stokes-Einstein relationship between dc conductivity and structural dynamics revealed some significant changes connected with the ability to form strong H-bonded structures. Moreover the presence of nearly constant loss (NCL) at moderate frequencies and just below the T(g) in the glassy state of levoglucosan and 1,6:2,3-dianhydro-β-D-mannopyranose was noticeable. We followed the temperature evolution of ε'' located at frequencies f = 0.1 kHz and f = 1 kHz, where the NCL is detected. Interestingly, a clear change in the dynamics far below the glass transition was observed in both compounds. This crossover (T(c)), found in different materials, and studied by various experimental techniques, is usually interpreted as being caused by the freezing of the Johari-Goldstein (JG) relaxation process. Alternatively it can also be due to the increasing anharmonicity in the density of vibrational states. Interestingly, it was shown that the slope of ε''(T) measured above the T(c) slightly changes while below the T(c) stays constant after physical aging. This is related to the densification of the sample that might result in steric hindrance and suppression of some kind of motion occurring in the glassy state, involving the larger parts of the molecules.
Broich, M.; Huete, A. R.; Xuanlon, M.; Davies, K.; Restrepo-Coupe, N.; Ratana, P.
2012-12-01
Australia's climate is extremely variable with inter-annual rainfall at any given site varying by 5- or 6-fold or more, across the continent. In addition to such inter-annual variability, there can be significant intra-annual variability, especially in monsoonal Australia (e.g. the wet tropical savannas) and Mediterranean climates in SW Australia where prolonged dry seasons occur each year. This presents unique challenges to the characterization of seasonal dynamics with satellite datasets. In contrast to annual reoccurring temperature-driven phenology of northern hemisphere mid-latitudes, vegetation dynamics of the vast and dry Australian interior are poorly quantified by existing remote sensing products. For example, in the current global-based MODIS phenology product, central Australia is covered by ~30% fill values for any given year. Two challenges are specific to Australian landscapes: first, the difficulty of characterizing seasonality of rainfall-driven ecosystems in interior Australia where duration and magnitude of green-up and brown down cycles show high inter annual variability; second, modeling two phenologic layers, the trees and the grass in savannas were the trees are evergreen but the herbaceous understory varies with rainfall. Savannas cover >50% of Australia. Australia's vegetation and climate are different from other continents. A MODIS phenology product capable of characterizing vegetation dynamics across the continent is being developed in this research as part of the AusCover national expert network aiming to provide Australian biophysical remote sensing data time-series and continental-scale map products. These products aim to support the Terrestrial Ecosystem Research Network (TERN) serving ecosystem research in Australia. The MODIS land surface product for Australia first searches the entire time series of each Climate Modeling Grid pixel for low-high-low extreme point sequences. A double logistic function is then fit to each of these
Levy-Bencheton, D; Terras, V
2015-01-01
We pursue our study of the antiperiodic dynamical 6-vertex model using Sklyanin's separation of variables approach, allowing in the model new possible global shifts of the dynamical parameter. We show in particular that the spectrum and eigenstates of the antiperiodic transfer matrix are completely characterized by a system of discrete equations. We prove the existence of different reformulations of this characterization in terms of functional equations of Baxter's type. We notably consider the homogeneous functional $T$-$Q$ equation which is the continuous analog of the aforementioned discrete system and show, in the case of a model with an even number of sites, that the complete spectrum and eigenstates of the antiperiodic transfer matrix can equivalently be described in terms of a particular class of its $Q$-solutions, hence leading to a complete system of Bethe equations. Finally, we compute the form factors of local operators for which we obtain determinant representations in finite volume.
A Variable Coefficient Method for Accurate Monte Carlo Simulation of Dynamic Asset Price
Li, Yiming; Hung, Chih-Young; Yu, Shao-Ming; Chiang, Su-Yun; Chiang, Yi-Hui; Cheng, Hui-Wen
2007-07-01
In this work, we propose an adaptive Monte Carlo (MC) simulation technique to compute the sample paths for the dynamical asset price. In contrast to conventional MC simulation with constant drift and volatility (μ,σ), our MC simulation is performed with variable coefficient methods for (μ,σ) in the solution scheme, where the explored dynamic asset pricing model starts from the formulation of geometric Brownian motion. With the method of simultaneously updated (μ,σ), more than 5,000 runs of MC simulation are performed to fulfills basic accuracy of the large-scale computation and suppresses statistical variance. Daily changes of stock market index in Taiwan and Japan are investigated and analyzed.
Variable-Temperature Tip-Enhanced Raman Spectroscopy of Single-Molecule Fluctuations and Dynamics.
Park, Kyoung-Duck; Muller, Eric A; Kravtsov, Vasily; Sass, Paul M; Dreyer, Jens; Atkin, Joanna M; Raschke, Markus B
2016-01-13
Structure, dynamics, and coupling involving single-molecules determine function in catalytic, electronic or biological systems. While vibrational spectroscopy provides insight into molecular structure, rapid fluctuations blur the molecular trajectory even in single-molecule spectroscopy, analogous to spatial averaging in measuring large ensembles. To gain insight into intramolecular coupling, substrate coupling, and dynamic processes, we use tip-enhanced Raman spectroscopy (TERS) at variable and cryogenic temperatures, to slow and control the motion of a single molecule. We resolve intrinsic line widths of individual normal modes, allowing detailed and quantitative investigation of the vibrational modes. From temperature dependent line narrowing and splitting, we quantify ultrafast vibrational dephasing, intramolecular coupling, and conformational heterogeneity. Through statistical correlation analysis of fluctuations of individual modes, we observe rotational motion and spectral fluctuations of the molecule. This work demonstrates single-molecule vibrational spectroscopy beyond chemical identification, opening the possibility for a complete picture of molecular motion ranging from femtoseconds to minutes.
Variable Quality Compression of Fluid Dynamical Data Sets Using a 3D DCT Technique
Loddoch, A.; Schmalzl, J.
2005-12-01
In this work we present a data compression scheme that is especially suited for the compression of data sets resulting from computational fluid dynamics (CFD). By adopting the concept of the JPEG compression standard and extending the approach of Schmalzl (Schmalzl, J. Using standard image compression algorithms to store data from computational fluid dynamics. Computers and Geosciences, 29, 10211031, 2003) we employ a three-dimensional discrete cosine transform of the data. The resulting frequency components are rearranged, quantized and finally stored using Huffman-encoding and standard variable length integer codes. The compression ratio and also the introduced loss of accuracy can be adjusted by means of two compression parameters to give the desired compression profile. Using the proposed technique compression ratios of more than 60:1 are possible with an mean error of the compressed data of less than 0.1%.
Giorgino, Toni; Laio, Alessandro; Rodriguez, Alex
2017-08-01
Molecular dynamics (MD) simulations allow the exploration of the phase space of biopolymers through the integration of equations of motion of their constituent atoms. The analysis of MD trajectories often relies on the choice of collective variables (CVs) along which the dynamics of the system is projected. We developed a graphical user interface (GUI) for facilitating the interactive choice of the appropriate CVs. The GUI allows: defining interactively new CVs; partitioning the configurations into microstates characterized by similar values of the CVs; calculating the free energies of the microstates for both unbiased and biased (metadynamics) simulations; clustering the microstates in kinetic basins; visualizing the free energy landscape as a function of a subset of the CVs used for the analysis. A simple mouse click allows one to quickly inspect structures corresponding to specific points in the landscape.
Directory of Open Access Journals (Sweden)
Wei Shang
2015-01-01
Full Text Available This paper investigates the terminal guidance problem for the missile intercepting a maneuvering target with impact time constraint. An impact time guidance law based on finite time convergence control theory is developed regarding the target motion as an unknown disturbance. To further improve the performance of the guidance law, an autopilot dynamics which is considered as a first-order lag is taken into consideration. In the proposed method, the coefficients change with the relative distance between missile and target. This variable coefficient strategy ensures that the missile impacts the target at the desired time with little final miss distance. Then it is proved that states of the guidance system converge to sliding mode in finite time under the proposed guidance law. Numerical simulations are presented to demonstrate the effectiveness of the impact time guidance law with autopilot dynamics (ITGAD.
Dynamical forcing of sub-seasonal variability in the tropical Brewer-Dobson circulation
Abalos, Marta; Randel, William; Serrano, Encarna
2014-05-01
Upwelling across the tropical tropopause exhibits strong sub-seasonal variability superimposed on the well-known annual cycle, and these variations directly affect temperature and tracers in the tropical lower stratosphere. The dynamical forcing of tropical upwelling on sub-seasonal timescales is investigated using the ERA-Interim reanalysis for 1979-2011. Momentum balance diagnostics reveal that transience is linked to the effects of extratropical wave forcing, with centers of action in the extratropical winter stratosphere and in the subtropical upper troposphere of both hemispheres. From a diagnostic point of view, the zonal-mean wind transient response is important for communicating the remote wave forcing to the tropical stratosphere. Dynamical patterns reflect distinctive forcing of the shallow versus deep branches of the Brewer-Dobson circulation.
Bathellier, Brice; Tee, Sui Poh; Hrovat, Christina; Rumpel, Simon
2013-12-03
Both in humans and in animals, different individuals may learn the same task with strikingly different speeds; however, the sources of this variability remain elusive. In standard learning models, interindividual variability is often explained by variations of the learning rate, a parameter indicating how much synapses are updated on each learning event. Here, we theoretically show that the initial connectivity between the neurons involved in learning a task is also a strong determinant of how quickly the task is learned, provided that connections are updated in a multiplicative manner. To experimentally test this idea, we trained mice to perform an auditory Go/NoGo discrimination task followed by a reversal to compare learning speed when starting from naive or already trained synaptic connections. All mice learned the initial task, but often displayed sigmoid-like learning curves, with a variable delay period followed by a steep increase in performance, as often observed in operant conditioning. For all mice, learning was much faster in the subsequent reversal training. An accurate fit of all learning curves could be obtained with a reinforcement learning model endowed with a multiplicative learning rule, but not with an additive rule. Surprisingly, the multiplicative model could explain a large fraction of the interindividual variability by variations in the initial synaptic weights. Altogether, these results demonstrate the power of multiplicative learning rules to account for the full dynamics of biological learning and suggest an important role of initial wiring in the brain for predispositions to different tasks.
Parreño, María A; Scannapieco, Alejandra C; Remis, María I; Juri, Marianela; Vera, María T; Segura, Diego F; Cladera, Jorge L; Lanzavecchia, Silvia B
2014-01-01
Anastrepha fraterculus is one of the most important fruit fly plagues in the American continent and only chemical control is applied in the field to diminish its population densities. A better understanding of the genetic variability during the introduction and adaptation of wild A. fraterculus populations to laboratory conditions is required for the development of stable and vigorous experimental colonies and mass-reared strains in support of successful Sterile Insect Technique (SIT) efforts. The present study aims to analyze the dynamics of changes in genetic variability during the first six generations under artificial rearing conditions in two populations: a) a wild population recently introduced to laboratory culture, named TW and, b) a long-established control line, named CL. Results showed a declining tendency of genetic variability in TW. In CL, the relatively high values of genetic variability appear to be maintained across generations and could denote an intrinsic capacity to avoid the loss of genetic diversity in time. The impact of evolutionary forces on this species during the adaptation process as well as the best approach to choose strategies to introduce experimental and mass-reared A. fraterculus strains for SIT programs are discussed.
Learning dynamics of a single polar variable complex-valued neuron.
Nitta, Tohru
2015-05-01
This letter investigates the characteristics of the complex-valued neuron model with parameters represented by polar coordinates (called polar variable complex-valued neuron). The parameters of the polar variable complex-valued neuron are unidentifiable. The plateau phenomenon can occur during learning of the polar variable complex-valued neuron. Furthermore, computer simulations suggest that a single polar variable complex-valued neuron has the following characteristics in the case of using the steepest gradient-descent method with square error: (1) unidentifiable parameters (singular points) degrade the learning speed and (2) a plateau can occur during learning. When the weight is attracted to the singular point, the learning tends to become stuck. However, computer simulations also show that the steepest gradient-descent method with amplitude-phase error and the complex-valued natural gradient method could reduce the effects of the singular points. The learning dynamics near singular points depends on the error functions and the training algorithms used.
State Anxiety and Nonlinear Dynamics of Heart Rate Variability in Students
Dimitriev, Aleksey D.
2016-01-01
Objectives Clinical and experimental research studies have demonstrated that the emotional experience of anxiety impairs heart rate variability (HRV) in humans. The present study investigated whether changes in state anxiety (SA) can also modulate nonlinear dynamics of heart rate. Methods A group of 96 students volunteered to participate in the study. For each student, two 5-minute recordings of beat intervals (RR) were performed: one during a rest period and one just before a university examination, which was assumed to be a real-life stressor. Nonlinear analysis of HRV was performed. The Spielberger’s State-Trait Anxiety Inventory was used to assess the level of SA. Results Before adjusting for heart rate, a Wilcoxon matched pairs test showed significant decreases in Poincaré plot measures, entropy, largest Lyapunov exponent (LLE), and pointwise correlation dimension (PD2), and an increase in the short-term fractal-like scaling exponent of detrended fluctuation analysis (α1) during the exam session, compared with the rest period. A Pearson analysis indicated significant negative correlations between the dynamics of SA and Poincaré plot axes ratio (SD1/SD2), and between changes in SA and changes in entropy measures. A strong negative correlation was found between the dynamics of SA and LLE. A significant positive correlation was found between the dynamics of SA and α1. The decreases in Poincaré plot measures (SD1, complex correlation measure), entropy measures, and LLE were still significant after adjusting for heart rate. Corrected α1 was increased during the exam session. As before, the dynamics of adjusted LLE was significantly correlated with the dynamics of SA. Conclusions The qualitative increase in SA during academic examination was related to the decrease in the complexity and size of the Poincaré plot through a reduction of both the interbeat interval and its variation. PMID:26807793
State Anxiety and Nonlinear Dynamics of Heart Rate Variability in Students.
Directory of Open Access Journals (Sweden)
Dimitriy A Dimitriev
Full Text Available Clinical and experimental research studies have demonstrated that the emotional experience of anxiety impairs heart rate variability (HRV in humans. The present study investigated whether changes in state anxiety (SA can also modulate nonlinear dynamics of heart rate.A group of 96 students volunteered to participate in the study. For each student, two 5-minute recordings of beat intervals (RR were performed: one during a rest period and one just before a university examination, which was assumed to be a real-life stressor. Nonlinear analysis of HRV was performed. The Spielberger's State-Trait Anxiety Inventory was used to assess the level of SA.Before adjusting for heart rate, a Wilcoxon matched pairs test showed significant decreases in Poincaré plot measures, entropy, largest Lyapunov exponent (LLE, and pointwise correlation dimension (PD2, and an increase in the short-term fractal-like scaling exponent of detrended fluctuation analysis (α1 during the exam session, compared with the rest period. A Pearson analysis indicated significant negative correlations between the dynamics of SA and Poincaré plot axes ratio (SD1/SD2, and between changes in SA and changes in entropy measures. A strong negative correlation was found between the dynamics of SA and LLE. A significant positive correlation was found between the dynamics of SA and α1. The decreases in Poincaré plot measures (SD1, complex correlation measure, entropy measures, and LLE were still significant after adjusting for heart rate. Corrected α1 was increased during the exam session. As before, the dynamics of adjusted LLE was significantly correlated with the dynamics of SA.The qualitative increase in SA during academic examination was related to the decrease in the complexity and size of the Poincaré plot through a reduction of both the interbeat interval and its variation.
Dynamics of sexual populations structured by a space variable and a phenotypical trait
Mirrahimi, Sepideh
2013-03-01
We study sexual populations structured by a phenotypic trait and a space variable, in a non-homogeneous environment. Departing from an infinitesimal model, we perform an asymptotic limit to derive the system introduced in Kirkpatrick and Barton (1997). We then perform a further simplification to obtain a simple model. Thanks to this simpler equation, we can describe rigorously the dynamics of the population. In particular, we provide an explicit estimate of the invasion speed, or extinction speed of the species. Numerical computations show that this simple model provides a good approximation of the original infinitesimal model, and in particular describes quite well the evolution of the species\\' range. © 2013 Elsevier Inc.
Dynamical Stability and Attractor of the Variable Generalized Chaplygin Gas Model
Institute of Scientific and Technical Information of China (English)
FU Huan-Huan; WU Ya-Bo; CHENG Fang-Yuan
2009-01-01
For the variable generalized Chaplygin gas (VGCG) as a dynamical system,its stability is analyzed and the related dynamical attractors are investigated.By analysis it is shown that there are two critical points corresponding to the matter-dominated phase and the VGCG dark energy-dominated phase,respectively.Moreover,when the parameters n,α and γ take some fixed values,the phase with ωVGCG=-0.92 is a dynamical attractor and the equation of state of VGCG reaches it from either ωVGCG＞-1 or ωVGCG＜-1,independent of the initial values of the dynamical system.This shows a satisfactory cosmological model:the early matter-dominated era,followed by the dark energy-dominated era.Meanwhile,the evolutions of density parameters Ωγ and ΩVGCG are quite different from each other.For different initial values of x and y,Ωγ decreases and flVGCG increases as the time grows,they will eventually approach Ωγ= 0 and ΩVGCG = 1.Furthermore,since different values of n or α may lead to different equation-of-state parameters ωVGC,we also discuss the constraints on the parameters n and α by the observation data.
Sindhu M R; Aneesh P; Manjula G Nair; T N P Nambiar
2014-01-01
Variable speed drives are mostly preferred in industries, while considering energy saving, smooth control, flexible operation and fast response. On the other hand, this equipment generates dynamic harmonic distortions in source currents and draws variable reactive power demand depending on variation in load condition. These distortions propagate throughout the system and affect all the loads connected to the point of common coupling. Hence a dynamic harmonic and reactive compensator is necess...
Vos, J. J.; Kalmar, A. F.; Struys, M. M. R. F.; Wietasch, J. K. G.; Hendriks, H. G. D.; Scheeren, T. W. L.
2013-01-01
Dynamic preload variables to predict fluid responsiveness are based either on the arterial pressure waveform (APW) or on the plethysmographic waveform (PW). We compared the ability of APW-based variations in stroke volume (SVV) and pulse pressure (PPV) and of PW-based plethysmographic variability in
Vos, J. J.; Kalmar, A. F.; Struys, M. M. R. F.; Wietasch, J. K. G.; Hendriks, H. G. D.; Scheeren, T. W. L.
Dynamic preload variables to predict fluid responsiveness are based either on the arterial pressure waveform (APW) or on the plethysmographic waveform (PW). We compared the ability of APW-based variations in stroke volume (SVV) and pulse pressure (PPV) and of PW-based plethysmographic variability
Vos, J. J.; Kalmar, A. F.; Struys, M. M. R. F.; Wietasch, J. K. G.; Hendriks, H. G. D.; Scheeren, T. W. L.
2013-01-01
Dynamic preload variables to predict fluid responsiveness are based either on the arterial pressure waveform (APW) or on the plethysmographic waveform (PW). We compared the ability of APW-based variations in stroke volume (SVV) and pulse pressure (PPV) and of PW-based plethysmographic variability in
Mukhin, Dmitry; Gavrilov, Andrey; Loskutov, Evgeny; Feigin, Alexander
2016-04-01
We suggest a method for empirical forecast of climate dynamics basing on the reconstruction of reduced dynamical models in a form of random dynamical systems [1,2] derived from observational time series. The construction of proper embedding - the set of variables determining the phase space the model works in - is no doubt the most important step in such a modeling, but this task is non-trivial due to huge dimension of time series of typical climatic fields. Actually, an appropriate expansion of observational time series is needed yielding the number of principal components considered as phase variables, which are to be efficient for the construction of low-dimensional evolution operator. We emphasize two main features the reduced models should have for capturing the main dynamical properties of the system: (i) taking into account time-lagged teleconnections in the atmosphere-ocean system and (ii) reflecting the nonlinear nature of these teleconnections. In accordance to these principles, in this report we present the methodology which includes the combination of a new way for the construction of an embedding by the spatio-temporal data expansion and nonlinear model construction on the basis of artificial neural networks. The methodology is aplied to NCEP/NCAR reanalysis data including fields of sea level pressure, geopotential height, and wind speed, covering Northern Hemisphere. Its efficiency for the interannual forecast of various climate phenomena including ENSO, PDO, NAO and strong blocking event condition over the mid latitudes, is demonstrated. Also, we investigate the ability of the models to reproduce and predict the evolution of qualitative features of the dynamics, such as spectral peaks, critical transitions and statistics of extremes. This research was supported by the Government of the Russian Federation (Agreement No. 14.Z50.31.0033 with the Institute of Applied Physics RAS) [1] Y. I. Molkov, E. M. Loskutov, D. N. Mukhin, and A. M. Feigin, "Random
Stargate of the Hidden Multiverse
Directory of Open Access Journals (Sweden)
Alexander Antonov
2016-02-01
Full Text Available Concept of Monoverse, which corresponds to the existing broad interpretation of the second postulate of the special theory of relativity, is not consistent with the modern astrophysical reality — existence of the dark matter and the dark energy, the total mass-energy of which is ten times greater than the mass-energy of the visible universe (which has been considered as the entire universe until very recent . This concept does not allow to explain their rather unusual properties — invisibility and lack of baryon content — which would seem to even destroy the very modern understanding of the term ‘matter’. However, all numerous alternative concepts of Multiverses, which have been proposed until today, are unable to explain these properties of the dark matter and dark energy. This article describes a new concept: the concept of the hidden Multiverse and hidden Supermultiverse, which mutual invisibility of parallel universes is explained by the physical reality of imaginary numbers. This concept completely explains the phenomenon of the dark matter and the dark energy. Moreover, it is shown that the dark matter and the dark energy are the experimental evidence for the existence of the hidden Multiverse. Described structure of the hidden Multiverse is fully consistent with the data obtained by the space stations WMAP and Planck. An extremely important property of the hidden Multiverse is an actual possibility of its permeation through stargate located on the Earth.
Hidden photons in connection to dark matter
Energy Technology Data Exchange (ETDEWEB)
Andreas, Sarah; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Goodsell, Mark D. [CPhT, Ecole Polytechnique, Palaiseau (France)
2013-06-15
Light extra U(1) gauge bosons, so called hidden photons, which reside in a hidden sector have attracted much attention since they are a well motivated feature of many scenarios beyond the Standard Model and furthermore could mediate the interaction with hidden sector dark matter.We review limits on hidden photons from past electron beam dump experiments including two new limits from such experiments at KEK and Orsay. In addition, we study the possibility of having dark matter in the hidden sector. A simple toy model and different supersymmetric realisations are shown to provide viable dark matter candidates in the hidden sector that are in agreement with recent direct detection limits.
Dynamic Modeling of Hydraulic Power Steering System with Variable Ratio Rack and Pinion Gear
Zhang, Nong; Wang, Miao
A comprehensive mathematical model of a typical hydraulic power steering system equipped with variable ratio rack and pinion gear is developed. The steering system’s dynamic characteristics are investigated and its forced vibrations are compared with those obtained from a counterpart system with a constant ratio rack and pinion gear. The modeling details of the mechanism subsystem, hydraulic supply lines subsystem and the rotary spool valve subsystem are provided and included in the integrated steering system model. The numerical simulations are conducted to investigate the dynamics of the nonlinear parametric steering system. From the comparison between simulated results and the experimental ones, it is shown that the model accurately integrates the boost characteristics of the rotary spool valve which is the key component of hydraulic power steering system. The variable ratio rack-pinion gear behaviors significantly differently from its constant ratio counterpart does. It significantly affects not only the system natural frequencies but also reduces vibrations under constant rate and ramp torque steering inputs. The developed steering model produces valid predictions of the system’s behavior and therfore could assist engineers in the design and analysis of integrated steering systems.
Dynamics of a variable mass system applied to spacecraft rocket attitude theory
Mudge, Jason Dominic
This research project is a study of the dynamics of a variable mass system. The scope of this research project is to gain understanding as to how a variable mass system will behave. The intent is to bring the level of understanding of variable mass dynamics higher and closer to the level of constant mass dynamics in the area of spacecrafts in particular. A main contribution is the finding of a set of criteria to minimize or eliminate the deviation of the nutation angle (or cone angle or angle of attack) of spacecraft rockets passively, i.e. without active control. The motivation for this research project is the Star 48 anomaly. The Star 48 is a solid rocket motor which has propelled (boosted) communication satellites from lower earth orbit to a higher one during the 1980's. The anomaly is that when the spacecraft rocket is being propelled, the nutation angle may deviate excessively which is considered undesirable. In the first part of this research project, a variable mass system is described and defined and the governing equations are derived. The type of governing equations derived are those that are most useful for analyzing the motion of a spacecraft rocket. The method of derivation makes use of Leibnitz Theorem, Divergence Theorem and Newton's Second Law of Motion. Next, the governing equations are specialized with several assumptions which are generally accepted assumptions applied in the analysis of spacecraft rockets. With these assumptions, the form governing equations is discussed and then the equations are solved analytically for the system's angular velocity. Having solved for the angular velocity of the system, the attitude of the system is obtained using a unique method which circumvents the nonlinearities that exist using Euler Angles and their kinematical equations. The attitude is approximately found analytically and a set of criteria is discussed which will minimize or eliminate the deviation of the nutation angle of a spacecraft rocket. Finally
Analytic Solution of the Three-Variable Dynamical Equations of Oscillation Phenomena in B-Z Reaction
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The dynamical behaviour of the inorganic bromate oscillator catalyzed by manganese ions in the B-Z reaction is discussed, a three-variable nonlinear dynamical equations of the oscillation phenomena have been obtained, and an analytic solution and numerical results of the equations are given.
Institute of Scientific and Technical Information of China (English)
SHI Lian-shuan; WANG Yue-fang; SUN Huan-chun
2006-01-01
A mathematical model was developed for layout optimization of truss structures with discrete variables subjected to dynamic stress, dynamic displacement and dynamic stability constraints. By using the quasi-static method, the mathematical model of structure optimization under dynamic stress, dynamic displacement and dynamic stability constraints were transformed into one subjected to static stress, displacement and stability constraints. The optimization procedures include two levels, i.e., the topology optimization and the shape optimization. In each level, the comprehensive algorithm was used and the relative difference quotients of two kinds of variables were used to search the optimum solution. A comparison between the optimum results of model with stability constraints and the optimum results of model without stability constraint was given. And that shows the stability constraints have a great effect on the optimum solutions.
Dynamic response of thin-walled structures by variable kinematic one-dimensional models
Carrera, E.; Varello, A.
2012-11-01
This paper investigates the accuracy capabilities of using variable kinematic modeling in compact and thin-walled beam-like structures with dynamic loadings. Carrera Unified Formulation (CUF) is employed to introduce refined one-dimensional (1D) models with a variable order of expansion for the displacement unknowns over the beam cross-section. Classical Euler-Bernoulli and Timoshenko beam theories are obtained as particular cases of these variable kinematic models while a higher order expansion permits the detection of in-plane cross-section deformation, since it leads to shell-like solutions. Finite element (FE) method is used to provide numerical results and the Newmark method is implemented as a time integration scheme. Some assessments with closed form solutions are discussed and comparisons with shell-type results obtained with commercial FE software are made. Further analyses address both compact and thin-walled cross-sections. In particular, the case of a deformable thin-walled cylinder loaded by time-dependent internal forces is discussed. The results clearly show that finite elements which are formulated in the CUF framework do not introduce additional numerical problems with respect to classical beam theories. Comparisons with elasticity solutions prove that the present 1D CUF model offers an accuracy in analyzing thin-walled structures which is typical of shell or three-dimensional models with a remarkable reduction in the computational cost required.
Temperature-variable high-frequency dynamic modeling of PIN diode
Shangbin, Ye; Jiajia, Zhang; Yicheng, Zhang; Yongtao, Yao
2016-04-01
The PIN diode model for high frequency dynamic transient characteristic simulation is important in conducted EMI analysis. The model should take junction temperature into consideration since equipment usually works at a wide range of temperature. In this paper, a temperature-variable high frequency dynamic model for the PIN diode is built, which is based on the Laplace-transform analytical model at constant temperature. The relationship between model parameters and temperature is expressed as temperature functions by analyzing the physical principle of these parameters. A fast recovery power diode MUR1560 is chosen as the test sample and its dynamic performance is tested under inductive load by a temperature chamber experiment, which is used for model parameter extraction and model verification. Results show that the model proposed in this paper is accurate for reverse recovery simulation with relatively small errors at the temperature range from 25 to 120 °C. Project supported by the National High Technology and Development Program of China (No. 2011AA11A265).
Dynamic Assessment of Water Quality Based on a Variable Fuzzy Pattern Recognition Model
Directory of Open Access Journals (Sweden)
Shiguo Xu
2015-02-01
Full Text Available Water quality assessment is an important foundation of water resource protection and is affected by many indicators. The dynamic and fuzzy changes of water quality lead to problems for proper assessment. This paper explores a method which is in accordance with the water quality changes. The proposed method is based on the variable fuzzy pattern recognition (VFPR model and combines the analytic hierarchy process (AHP model with the entropy weight (EW method. The proposed method was applied to dynamically assess the water quality of Biliuhe Reservoir (Dailan, China. The results show that the water quality level is between levels 2 and 3 and worse in August or September, caused by the increasing water temperature and rainfall. Weights and methods are compared and random errors of the values of indicators are analyzed. It is concluded that the proposed method has advantages of dynamism, fuzzification and stability by considering the interval influence of multiple indicators and using the average level characteristic values of four models as results.
Spike-Threshold Variability Originated from Separatrix-Crossing in Neuronal Dynamics
Wang, Longfei; Wang, Hengtong; Yu, Lianchun; Chen, Yong
2016-08-01
The threshold voltage for action potential generation is a key regulator of neuronal signal processing, yet the mechanism of its dynamic variation is still not well described. In this paper, we propose that threshold phenomena can be classified as parameter thresholds and state thresholds. Voltage thresholds which belong to the state threshold are determined by the ‘general separatrix’ in state space. We demonstrate that the separatrix generally exists in the state space of neuron models. The general form of separatrix was assumed as the function of both states and stimuli and the previously assumed threshold evolving equation versus time is naturally deduced from the separatrix. In terms of neuronal dynamics, the threshold voltage variation, which is affected by different stimuli, is determined by crossing the separatrix at different points in state space. We suggest that the separatrix-crossing mechanism in state space is the intrinsic dynamic mechanism for threshold voltages and post-stimulus threshold phenomena. These proposals are also systematically verified in example models, three of which have analytic separatrices and one is the classic Hodgkin-Huxley model. The separatrix-crossing framework provides an overview of the neuronal threshold and will facilitate understanding of the nature of threshold variability.
The Hidden Costs of Offshoring
DEFF Research Database (Denmark)
Møller Larsen, Marcus; Manning, Stephan; Pedersen, Torben
2011-01-01
experience moderate the relationship between complexity and hidden costs negatively i.e. reduces the cost generating impact of complexity. We develop three hypotheses and test them on comprehensive data from the Offshoring Research Network (ORN). In general, we find support for our hypotheses. A key result...... of offshoring. Specifically, we propose that hidden costs can be explained by the combination of increasing structural, operational and social complexity of offshoring activities. In addition, we suggest that firm orientation towards organizational design as part of an offshoring strategy and offshoring...
Hidden symmetries in jammed systems
Morse, Peter K.; Corwin, Eric I.
2016-07-01
There are deep, but hidden, geometric structures within jammed systems, associated with hidden symmetries. These can be revealed by repeated transformations under which these structures lead to fixed points. These geometric structures can be found in the Voronoi tesselation of space defined by the packing. In this paper we examine two iterative processes: maximum inscribed sphere (MIS) inversion and a real-space coarsening scheme. Under repeated iterations of the MIS inversion process we find invariant systems in which every particle is equal to the maximum inscribed sphere within its Voronoi cell. Using a real-space coarsening scheme we reveal behavior in geometric order parameters which is length-scale invariant.
Hidden Crises and Communication : An Interactional Analysis of Hidden Crises
Klarenbeek, Annette
2011-01-01
In this paper I describe the ways in which the communication discipline can make a hidden crisis transparent. For this purpose I examine the concept of crisis entrepreneurship from a communication point of view. Using discourse analysis, I analyse the discursive practices of crisis entrepreneurs in
Climate Variability and Mangrove Cover Dynamics at Species Level in the Sundarbans, Bangladesh
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Manoj Kumer Ghosh
2017-05-01
Full Text Available Mangrove ecosystems are complex in nature. For monitoring the impact of climate variability in this ecosystem, a multidisciplinary approach is a prerequisite. Changes in temperature and rainfall pattern have been suggested as an influential factor responsible for the change in mangrove species composition and spatial distribution. The main aim of this study was to assess the relationship between temperature, rainfall pattern and dynamics of mangrove species in the Sundarbans, Bangladesh, over a 38 year time period from 1977 to 2015. To assess the relationship, a three stage analytical process was employed. Primarily, the trend of temperature and rainfall over the study period were identified using a linear trend model; then, the supervised maximum likelihood classifier technique was employed to classify images recorded by Landsat series and post-classification comparison techniques were used to detect changes at species level. The rate of change of different mangrove species was also estimated in the second stage. Finally, the relationship between temperature, rainfall and the dynamics of mangroves at species level was determined using a simple linear regression model. The results show a significant statistical relationship between temperature, rainfall and the dynamics of mangrove species. The trends of change for Heritiera fomes and Sonneratia apelatala show a strong relationship with temperature and rainfall, while Ceriops decandra shows a weak relationship. In contrast, Excoecaria agallocha and Xylocarpus mekongensis do not show any significant relationship with temperature and rainfall. On the basis of our results, it can be concluded that temperature and rainfall are important climatic factors influencing the dynamics of three major mangrove species viz. H. fomes, S. apelatala and C. decandra in the Sundarbans.
Dynamics of microbial growth and coexistence on variably saturated rough surfaces.
Long, Tao; Or, Dani
2009-08-01
The high degree of microbial diversity found in soils is attributed to the highly heterogeneous pore space and the dynamic aqueous microenvironments. Previous studies have shown that spatial and temporal variations in aqueous diffusion pathways play an important role in shaping microbial habitats and biological activity in unsaturated porous media. A new modeling framework was developed for the quantitative description of diffusion-dominated microbial interactions focusing on competitive growth of two microbial species inhabiting partially saturated rough surfaces. Surface heterogeneity was represented by patches with different porosities and water retention properties, yielding heterogeneous distribution of water contents that varies with changes in relative humidity or soil matric potential. Nutrient diffusion and microbial growth on the variably hydrated and heterogeneous surface was modeled using a hybrid method that combines a reaction diffusion method for nutrient field with individual based model for microbial growth and expansion. The model elucidated the effects of hydration dynamics and heterogeneity on nutrient fluxes and mobility affecting microbial population growth, expansion, and coexistence at the microscale. In contrast with single species dominance under wet conditions, results demonstrated prolonged coexistence of two competing species under drier conditions where nutrient diffusion and microbial movement were both limited. The uneven distribution of resources and diffusion pathways in heterogeneous surfaces highlighted the importance of position in the landscape for survival that may compensate for competitive disadvantages conferred by physiological traits. Increased motility was beneficial for expansion and survival. Temporal variations in hydration conditions resulted in fluctuations in microbial growth rate and population size. Population growth dynamics of the dominant species under wet-dry cycles were similar to growth under average value
O'Connor, Mike; Paci, Emanuele; McIntosh-Smith, Simon; Glowacki, David R
2016-12-22
The past decade has seen the development of a new class of rare event methods in which molecular configuration space is divided into a set of boundaries/interfaces, and then short trajectories are run between boundaries. For all these methods, an important concern is how to generate boundaries. In this paper, we outline an algorithm for adaptively generating boundaries along a free energy surface in multi-dimensional collective variable (CV) space, building on the boxed molecular dynamics (BXD) rare event algorithm. BXD is a simple technique for accelerating the simulation of rare events and free energy sampling which has proven useful for calculating kinetics and free energy profiles in reactive and non-reactive molecular dynamics (MD) simulations across a range of systems, in both NVT and NVE ensembles. Two key developments outlined in this paper make it possible to automate BXD, and to adaptively map free energy and kinetics in complex systems. First, we have generalized BXD to multidimensional CV space. Using strategies from rigid-body dynamics, we have derived a simple and general velocity-reflection procedure that conserves energy for arbitrary collective variable definitions in multiple dimensions, and show that it is straightforward to apply BXD to sampling in multidimensional CV space so long as the Cartesian gradients ∇CV are available. Second, we have modified BXD to undertake on-the-fly statistical analysis during a trajectory, harnessing the information content latent in the dynamics to automatically determine boundary locations. Such automation not only makes BXD considerably easier to use; it also guarantees optimal boundaries, speeding up convergence. We have tested the multidimensional adaptive BXD procedure by calculating the potential of mean force for a chemical reaction recently investigated using both experimental and computational approaches - i.e., F + CD3CN → DF + D2CN in both the gas phase and a strongly coupled explicit CD3CN solvent
Detecting Hidden Communications Protocols
2013-02-11
keyboards. We extracted the keystroke dynamics of each language. If there was no value for any key-pair, the neighbor list of the destination key was...this, we set up an experiment where text was transmitted through an SSH tunnel with the sequence of inter- keystroke delays following statistics...structure. The inter- keystroke time delays for the two languages differ due to a variety of factors including, but not limited to: • keyboard layout
Modeling Multiple Risks: Hidden Domain of Attraction
Mitra, Abhimanyu
2011-01-01
Hidden regular variation is a sub-model of multivariate regular variation and facilitates accurate estimation of joint tail probabilities. We generalize the model of hidden regular variation to what we call hidden domain of attraction. We exhibit examples that illustrate the need for a more general model and discuss detection and estimation techniques.
Pentaquark states with hidden charm
Bijker, Roelof
2017-07-01
I develop an extension of the usual three-flavor quark model to four flavors (u, d, s and c), and discuss the classification of pentaquark states with hidden charm. This work is motivated by the recent observation of such states by the LHCb Collatoration at CERN.
Microgenetic analysis of hidden figures
Directory of Open Access Journals (Sweden)
Marković Slobodan S.
2006-01-01
Full Text Available In this study the phenomenological and processual aspects of the perception of hidden figures were compared. The question was whether the more probable percepts of hidden figures, compared to the less probable percepts, were generated in earlier stages of the perceptual process. In the pilot study the subjects were asked to say what they see in a complex linear pattern. The three most frequent and the three least frequent perceptual descriptions were selected. In the experiment the microgenesis of the perception of hidden figures was investigated. The primed matching paradigm and the same-different task were used. In each experiment two types of test figures were contrasted: the more frequent and the less frequent ones. There were two prime types: identical (equal to test figures and complex (the pattern with hidden test figures. The prime duration was varied, 50 ms and 400 ms. The main result indicates that in the case of complex priming the more frequent test figures were processed significantly faster than the less frequent ones in both prime duration conditions. These results suggest that the faster the processing of a figure, the more probable the perceptual generation of this figure.
DEFF Research Database (Denmark)
Pedersen, Jørn Bjarke Torp; Kaufmann, Laura Hauch; Kroon, Aart
2010-01-01
’, and examines its spatial and temporal dynamics by analysis of recent satellite imagery, modelled meteorological data and historical data covering the last decade. The dominating mechanisms to form and sustain the polynya are inferred and the persistence and inter-annual variability of the phenomenon...... and summer regimes in the seasonal evolution of the polynya. During the winter regime, both the size of and the ice cover within the polynya varies significantly on a temporal and spatial scale. Intermittent wind-driven openings of the polynya alternate with periods of increasing ice cover. Some of the most...... persistent areas of open water in the polynya coincide with locations where significant concentrations of spring and summer settlements from the Thule Inuit culture (AD 1400-1850) are observed, indicating a connection between the presence of the polynya and the Thule Inuit living in the area in prehistoric...
DEFF Research Database (Denmark)
Pedersen, Jørn Bjarke Torp; Kaufmann, Laura Hauch; Kroon, Aart
2010-01-01
’, and examines its spatial and temporal dynamics by analysis of recent satellite imagery, modelled meteorological data and historical data covering the last decade. The dominating mechanisms to form and sustain the polynya are inferred and the persistence and inter-annual variability of the phenomenon...... are estimated. The polynya formation is predominantly governed by mechanical forcing caused by northerly gales, and it is classified as a wind-driven shelf water polynya. A marked seasonal difference in the surface wind field, together with the obvious seasonal cycle in insolation, creates distinct winter...... and summer regimes in the seasonal evolution of the polynya. During the winter regime, both the size of and the ice cover within the polynya varies significantly on a temporal and spatial scale. Intermittent wind-driven openings of the polynya alternate with periods of increasing ice cover. Some of the most...
Institute of Scientific and Technical Information of China (English)
ZHANG Yong-Chui; ZHANG Li-Feng; L(U) Qing-Ping
2011-01-01
In this study, the dynamic mechanisms of interannual sea surface height (SSH) variability are investigated based on the first-mode baroclinic Rossby wave model, with a focus on the effects of different levels of wind stress curl (WSC)、 Maximum covariance analysis (MCA) of WSC and SSH anomalies displays a mode with significant WSC anomalies located primarily in the mid-latitude eastern North Pacific and central tropical Pacific with corresponding SSH anomalies located to the west. This leading mode can be attributed to Ekman pumping induced by local wind stress and the westward-propagating Rossby wave driven by largescale wind stress. It is further found that in the middle latitudes, the SSH anomalies are largely determined by WSC variations associated with the North Pacific Gyre Oscillation (NPGO)、 rather than the Pacific Decadal Oscillation (PDO). The sensitivity of the predictive skill of the linear first-mode baroclinic model to different wind products is also examined.
On the non-equilibrium dynamics of cavitation around the underwater projectile in variable motion
Chen, Y.; Lu, C. J.; Li, J.; Chen, X.; Gong, Z. X.
2015-12-01
In this work, the dynamic behavior of the non-equilibrium cavitation occurring around the underwater projectiles navigating with variable speed was numerically and theoretically investigated. The cavity collapse induced by the decelerating motion of the projectiles can be classified into two types: periodic oscillation and damped oscillation. In each type the evolution of the total mass of vapor in cavity are found to have strict correlation with the pressure oscillation in far field. By defining the equivalent radius of cavity, we introduce the specific kinetic energy of collapse and demonstrate that its change-rate is in good agreement with the pressure disturbance. We numerically investigated the influence of angle of attack on the collapse effect. The result shows that when the projectile decelerates, an asymmetric-focusing effect of the pressure induced by collapse occurs on its pressure side. We analytically explained such asymmetric-focusing effect.
Garrett, Bruce C.; Swaminathan, P. K.; Murthy, C. S.; Redmon, Michael J.
1987-01-01
A variable time step algorithm has been implemented for solving the stochastic equations of motion for gas-surface collisions. It has been tested for a simple model of electronically inelastic collisions with an insulator surface in which the phonon manifold acts as a heat bath and electronic states are localized. In addition to reproducing the accurate nuclear dynamics of the surface atoms, numerical calculations have shown the algorithm to yield accurate ensemble averages of physical observables such as electronic transition probabilities and total energy loss of the gas atom to the surface. This new algorithm offers a gain in efficieny of up to an order of magnitude compared to fixed time step integration.
Off-Axis Orbits in Realistic Helical Wigglers Fixed Points and Time Averaged Dynamical Variables
ThomasDonohue, John
2004-01-01
Many years ago Fajans, Kirkpatrick and Bekefi studied off-axis orbits in a realistic helical wiggler, both experimentally and theoretically. They found that as the distance from the axis of symmetry to the guiding center increased, both the mean axial velocity and the precession frequency of the guiding center varied. . They proposed a clever semi-empirical model which yielded an excellent description of both these variations. We point out that a approximate model proposed by us several years ago can be made to predict these delicate effects correctly, provided we extend our truncated quadratic Hamiltonian to include appropriate cubic terms. We develop an argument similar to the virial theorem to compare time averaged and fixed-point values of dynamical variables. Illustrative comparisons of our model with numerical calculation are presented.
Directory of Open Access Journals (Sweden)
Khoa T D Thai
Full Text Available BACKGROUND: Dengue is a major global public health problem with increasing incidence and geographic spread. The epidemiology is complex with long inter-epidemic intervals and endemic with seasonal fluctuations. This study was initiated to investigate dengue transmission dynamics in Binh Thuan province, southern Vietnam. METHODOLOGY: Wavelet analyses were performed on time series of monthly notified dengue cases from January 1994 to June 2009 (i to detect and quantify dengue periodicity, (ii to describe synchrony patterns in both time and space, (iii to investigate the spatio-temporal waves and (iv to associate the relationship between dengue incidence and El Niño-Southern Oscillation (ENSO indices in Binh Thuan province, southern Vietnam. PRINCIPAL FINDINGS: We demonstrate a continuous annual mode of oscillation and a multi-annual cycle of around 2-3-years was solely observed from 1996-2001. Synchrony in time and between districts was detected for both the annual and 2-3-year cycle. Phase differences used to describe the spatio-temporal patterns suggested that the seasonal wave of infection was either synchronous among all districts or moving away from Phan Thiet district. The 2-3-year periodic wave was moving towards, rather than away from Phan Thiet district. A strong non-stationary association between ENSO indices and climate variables with dengue incidence in the 2-3-year periodic band was found. CONCLUSIONS: A multi-annual mode of oscillation was observed and these 2-3-year waves of infection probably started outside Binh Thuan province. Associations with climatic variables were observed with dengue incidence. Here, we have provided insight in dengue population transmission dynamics over the past 14.5 years. Further studies on an extensive time series dataset are needed to test the hypothesis that epidemics emanate from larger cities in southern Vietnam.
2016-01-01
DNA double-strand breaks are lesions that form during metabolism, DNA replication and exposure to mutagens. When a double-strand break occurs one of a number of repair mechanisms is recruited, all of which have differing propensities for mutational events. Despite DNA repair being of crucial importance, the relative contribution of these mechanisms and their regulatory interactions remain to be fully elucidated. Understanding these mutational processes will have a profound impact on our knowledge of genomic instability, with implications across health, disease and evolution. Here we present a new method to model the combined activation of non-homologous end joining, single strand annealing and alternative end joining, following exposure to ionising radiation. We use Bayesian statistics to integrate eight biological data sets of double-strand break repair curves under varying genetic knockouts and confirm that our model is predictive by re-simulating and comparing to additional data. Analysis of the model suggests that there are at least three disjoint modes of repair, which we assign as fast, slow and intermediate. Our results show that when multiple data sets are combined, the rate for intermediate repair is variable amongst genetic knockouts. Further analysis suggests that the ratio between slow and intermediate repair depends on the presence or absence of DNA-PKcs and Ku70, which implies that non-homologous end joining and alternative end joining are not independent. Finally, we consider the proportion of double-strand breaks within each mechanism as a time series and predict activity as a function of repair rate. We outline how our insights can be directly tested using imaging and sequencing techniques and conclude that there is evidence of variable dynamics in alternative repair pathways. Our approach is an important step towards providing a unifying theoretical framework for the dynamics of DNA repair processes. PMID:27741226
Weippert, Matthias; Behrens, Kristin; Rieger, Annika; Stoll, Regina; Kreuzfeld, Steffi
2013-01-01
Aim was to elucidate autonomic responses to dynamic and static (isometric) exercise of the lower limbs eliciting the same moderate heart rate (HR) response. 23 males performed two kinds of voluntary exercise in a supine position at similar heart rates: static exercise (SE) of the lower limbs (static leg press) and dynamic exercise (DE) of the lower limbs (cycling). Subjective effort, systolic (SBP) and diastolic blood pressure (DBP), mean arterial pressure (MAP), rate pressure product (RPP) and the time between consecutive heart beats (RR-intervals) were measured. Time-domain (SDNN, RMSSD), frequency-domain (power in the low and high frequency band (LFP, HFP)) and geometric measures (SD1, SD2) as well as non-linear measures of regularity (approximate entropy (ApEn), sample entropy (SampEn) and correlation dimension D2) were calculated. Although HR was similar during both exercise conditions (88±10 bpm), subjective effort, SBP, DBP, MAP and RPP were significantly enhanced during SE. HRV indicators representing overall variability (SDNN, SD 2) and vagal modulated variability (RMSSD, HFP, SD 1) were increased. LFP, thought to be modulated by both autonomic branches, tended to be higher during SE. ApEn and SampEn were decreased whereas D2 was enhanced during SE. It can be concluded that autonomic control processes during SE and DE were qualitatively different despite similar heart rate levels. The differences were reflected by blood pressure and HRV indices. HRV-measures indicated a stronger vagal cardiac activity during SE, while blood pressure response indicated a stronger sympathetic efferent activity to the vessels. The elevated vagal cardiac activity during SE might be a response mechanism, compensating a possible co-activation of sympathetic cardiac efferents, as HR and LF/HF was similar and LFP tended to be higher. However, this conclusion must be drawn cautiously as there is no HRV-marker reflecting "pure" sympathetic cardiac activity.
Horion, S.; Cornet, Y.; Erpicum, M.; Tychon, B.
2013-02-01
In this paper we investigated if and how a signature of climate control on vegetation growth can be individualized at regional scale using time series of SPOT-VEGETATION NDVI and ECMWF meteorological data. Twelve regions characterized by dominant and stable cropland or grassland covers were selected in Europe and Africa. Our results show that the relationship between NDVI and meteorological parameters is highly complex and significantly vary trough the phenological cycle of the plants. Hence, interactions between vegetation dynamics and climate variability must be studied at a smaller time scale in order to identify properly the limiting factors to vegetation growth. Using NDVI metrics, vegetative phases (from green-up to maximum NDVI) and reproductive phases (from maximum NDVI to maturity) were identified for each region. Cross-correlation analysis revealed that, in most of the cases, the best scores of Pearson's r are obtained when we considered the vegetative phase (from green-up to maximum of NDVI) and the reproductive phase (from maximum of NDVI to maturity) separately. We also showed that climatic constraints identified using yearly proxies of climate and vegetation do not depict correctly or completely the climate control on vegetation development. In that sense the complexity of the climate-vegetation relationship, which is spatially and temporally variable, is well underlined in this study.
Effects of long-term variability on projections of twenty-first century dynamic sea level
Bordbar, Mohammad H.; Martin, Thomas; Latif, Mojib; Park, Wonsun
2015-04-01
Sea-level rise is one of the most pressing aspects of anthropogenic global warming with far-reaching consequences for coastal societies. However, sea-level rise did and will strongly vary from coast to coast. Here we investigate the long-term internal variability effects on centennial projections of dynamic sea level (DSL), the local departure from the globally averaged sea level. A large ensemble of global warming integrations has been conducted with a climate model, where each realization was forced by identical CO2 increase but started from different atmospheric and oceanic initial conditions. In large parts of the mid- and high latitudes, the ensemble spread of the projected centennial DSL trends is of the same order of magnitude as the globally averaged steric sea-level rise, suggesting that internal variability cannot be ignored when assessing twenty-first-century DSL trends. The ensemble spread is considerably reduced in the mid- to high latitudes when only the atmospheric initial conditions differ while keeping the oceanic initial state identical; indicating that centennial DSL projections are strongly dependent on ocean initial conditions.
Long-Term Internal Variability Effects on Centennial Dynamic Sea Level Projections
Hadi Bordbar, Mohammad; Martin, Thomas; Park, Wonsun; Latif, Mojib
2015-04-01
The Earth's surface is warming in response to anthropogenic emissions of greenhouse gases, especially carbon dioxide (CO2). Sea level rise is one of the most pressing aspects of global warming with far-reaching consequences for coastal societies. However, sea level rise did and will strongly vary from coast to coast. Here we investigate the long-term internal variability effects on centennial projections of dynamic sea level (DSL), the local departure from the globally averaged sea level. A large ensemble of global warming integrations was conducted with a climate model, where each ensemble member was forced by identical CO2-increase but started from different atmospheric and oceanic initial conditions taken from an unforced millennial control run. In large parts of the mid- and high latitudes, the ensemble spread of the projected centennial DSL trends is of the same order of magnitude as the globally averaged steric sea level rise, suggesting internal variability cannot be ignored when assessing 21st century DSL changes. This conclusion is also supported by analyzing projections with other climate models. The ensemble spread is strongly reduced in the mid- to high latitudes if only the atmospheric initial conditions are perturbed; suggesting uncertainty in the projected centennial DSL trends there is largely due to the lack of ocean information. Thus climate model projections of regional sea level would benefit from ocean initialization.
Variability properties and Disk dynamics in GX 339-4 during its outbursts
Gopal Dutta, Broja; Chakrabarti, Sandip Kumar
2016-07-01
In the propagating oscillatory shock model, the evolution of QPO frequency is explained by systematic variation of Compton cloud size, i.e., steady radial movement of the shock front which is triggered by cooling of the post-shock region. Studies of energy dependent temporal properties in different variability time scales can thus diagnose dynamics and geometry of accretion flows around black holes. We study time variability properties for the low inclination black hole source GX 339-4 during its 2002, 2004, 2007 and 2010 outbursts using RXTE/PCA data. We find only hard lag (i.e., hard photon lags behind soft photons) for all outbursts (2002, 2004, 2007, 2010). We study time lag with the variation of shock location. We find that lag increases as the size of the Comptonizing region increases as in two component advective flow solution. We explain all possible mechanisms and showed that if we add up the qualitative variations of lags, then the high inclination objects could have negative time lags due to reflection and focusing effects. We explain lag behaviour within the framework of a single two component advective flow model.
Kuo, Yi-Ming; Wu, Jiunn-Tzong
2016-12-01
This study was conducted to identify the key factors related to the spatiotemporal variations in phytoplankton abundance in a subtropical reservoir from 2006 to 2010 and to assist in developing strategies for water quality management. Dynamic factor analysis (DFA), a dimension-reduction technique, was used to identify interactions between explanatory variables (i.e., environmental variables) and abundance (biovolume) of predominant phytoplankton classes. The optimal DFA model significantly described the dynamic changes in abundances of predominant phytoplankton groups (including dinoflagellates, diatoms, and green algae) at five monitoring sites. Water temperature, electrical conductivity, water level, nutrients (total phosphorus, NO3-N, and NH3-N), macro-zooplankton, and zooplankton were the key factors affecting the dynamics of aforementioned phytoplankton. Therefore, transformations of nutrients and reactions between water quality variables and aforementioned processes altered by hydrological conditions may also control the abundance dynamics of phytoplankton, which may represent common trends in the DFA model. The meandering shape of Shihmen Reservoir and its surrounding rivers caused a complex interplay between hydrological conditions and abiotic and biotic variables, resulting in phytoplankton abundance that could not be estimated using certain variables. Additional water quality and hydrological variables at surrounding rivers and monitoring plans should be executed a few days before and after reservoir operations and heavy storm, which would assist in developing site-specific preventive strategies to control phytoplankton abundance.
Dynamic Analysis for a Geared Turbofan Engine with Variable Area Fan Nozzle
Csank, Jeffrey T.; Thomas, George L.
2017-01-01
Aggressive design goals have been set for future aero-propulsion systems with regards to fuel economy, noise, and emissions. To meet these challenging goals, advanced propulsion concepts are being explored and current operating margins are being re-evaluated to find additional concessions that can be made. One advanced propulsion concept being evaluated is a geared turbofan with a variable area fan nozzle (VAFN), developed by NASA. This engine features a small core, a fan driven by the low pressure turbine through a reduction gearbox, and a shape memory alloy (SMA)-actuated VAFN. The VAFN is designed to allow both a small exit area for efficient operation at cruise, while being able to open wider at high power conditions to reduce backpressure on the fan and ensure a safe level of stall margin is maintained. The VAFN is actuated via a SMA-based system instead of a conventional system to decrease overall weight of the system, however, SMA-based actuators respond relatively slowly, which introduces dynamic issues that are investigated in this work. This paper describes both a control system designed specifically for issues associated with SMAs, and dynamic analysis of the geared turbofan VAFN with the SMA actuators. Also, some future recommendations are provided for this type of propulsion system.
Montaldo, N.; Albertson, J. D.
2001-12-01
Meteorological and hydrological forecasting models share soil moisture as a critical boundary condition. Partitioning of received energy at the land surface depends directly on this variable, as does the partitioning of rainfall into its possible routes over and through the soil. In Land Surface Models (LSMs) the temporal dynamic of soil moisture spatial variability is a fundamental issue in large-scale flux predictions. From remote sensing observations soil moisture values are averaged in the horizontal over rather large regions (pixels). The averaging areas will be getting even larger as we move from aircraft mounted sensors to satellite mounting. These data are to be used ultimately to estimate spatial averages of other processes that depend on soil moisture, such as, runoff generation, drainage, evaporation, sensible heat fluxes, crop yield, microbial activity, etc. Consequently, the LSMs have to predict spatial averaged flux over large region from average values of the soil moisture. But soil moisture variances affect flux predictions, which depend nonlinearly on soil moisture, because many of the other processes possess distinct threshold aspects to their nonlinear dependence on soil moisture. Through application of well-developed Reynolds averaging rules from fluid mechanics to the equation of Richards and Darcy-Buckingham, we write a conservation equation for the horizontal variance of soil moisture. And, through closure arguments, we are able to describe the individual terms that produce and destroy spatial variance through time in terms of the mean soil moisture state and other observable system properties such as vegetation and soil properties variability. Finally, we calculate land surface fluxes from second order Taylor expansion, using our soil moisture variance closure model, and the other observable system properties. In this work, we demonstrate significant improvements in land surface large-scale flux predictions using the proposed soil moisture
Temporal Dynamics of Soil Moisture Variability: Implications For Land Surface Models
Montaldo, N.; Albertson, J. D.
Meteorological and hydrological forecasting models share soil moisture as a critical boundary condition. Partitioning of received energy at the land surface depends di- rectly on this variable, as does the partitioning of rainfall into its possible routes over and through the soil. In Land Surface Models (LSMs) the temporal dynamic of soil moisture spatial variability is a fundamental issue in large-scale flux predictions. From remote sensing observations soil moisture values are averaged in the horizontal over rather large regions (pixels). The averaging areas will be getting even larger as we move from aircraft mounted sensors to satellite mounting. These data are to be used ultimately to estimate spatial averages of other processes that depend on soil moisture, such as, runoff generation, drainage, evaporation, sensible heat fluxes, crop yield, mi- crobial activity, etc. Consequently, the LSMs have to predict spatial averaged flux over large region from average values of the soil moisture. But soil moisture variances af- fect flux predictions, which depend nonlinearly on soil moisture, because many of the other processes possess distinct threshold aspects to their nonlinear dependence on soil moisture. Through application of well-developed Reynolds averaging rules from fluid mechanics to the equation of Richards and Darcy-Buckingham, we write a con- servation equation for the horizontal variance of soil moisture. And, through closure arguments, we are able to describe the individual terms that produce and destroy spa- tial variance through time in terms of the mean soil moisture state and other observable system properties such as vegetation and soil properties variability. Finally, we calcu- late land surface fluxes from second order Taylor expansion, using our soil moisture variance closure model, and the other observable system properties. In this work, we demonstrate significant improvements in land surface large-scale flux predictions us- ing the proposed
Occurrence of a bimodal behavior in riparian vegetation dynamics driven by river flow variability
Camporeale, C.; Ridolfi, L.
2006-12-01
The riparian zone is a fluvial ecotone which exhibits very interesting interaction between hydraulics and ecology, with several important implications in the environmental management. Even though random variability is a key characteristic of the river hydrology, which plays a crucial role in the evolution of riparian vegetation, the impact of stochastic hydrologic fluctuations on the dynamics of riparian vegetation ecosystems remains for most part poorly understood. Here we propose a new approach to study the distribution of phreatophyte riparian vegetation, using a stochastic process to model the random forcing exerted by river flow on the dynamics of the overall biomass of vegetation. Growth and decrease of vegetation are modelled through a logistic and an exponential functions, respectively, which switch in a random way, depending on the flooding conditions. The time series of the river flow (described by the pdf and autocorrelation function), determines the corresponding time series of the water levels which in turn drives the statistical characteristics of the switching. In the logistic model, the carrying capacity is taken dependent on the water table depth through a quadratic optimum function with species-dependent parameters. A dimensional analysis shows that the fundamental factors are the autocorrelation function of the flow, the coefficient of variation, the ratio between growth and decrease rate of vegetation and the optimum water table depth. The switching dynamics is shown to be described by a single stochastic differential equation driven by dichotomic noise that is analytically solved herein. The main outcome is the pdf of the vegetation biomass at the steady state which allows the stability of the models and the central moments to be investigated. Bimodality of the solution and peculiar behaviors (e.g., noise-induced stability) are discussed, depending on the river geometry and the hydrological characteristics. The obtained analytical expressions
The dynamics of laterally variable subductions: laboratory models applied to the Hellenides
Directory of Open Access Journals (Sweden)
B. Guillaume
2013-04-01
Full Text Available We design three-dimensional dynamically self-consistent laboratory models of subduction to analyze the relationships between overriding plate deformation and subduction dynamics in the upper mantle. We investigate the effects of the subduction of a lithosphere of laterally variable buoyancy on the temporal evolution of trench kinematics and shape, horizontal flow at the top of the asthenosphere, dynamic topography and deformation of the overriding plate. The interface between the two units, analogue to a trench-perpendicular tear fault between a negatively buoyant oceanic plate and positively buoyant continental one, is either fully-coupled or shear-stress free. Differential rates of trench retreat, in excess of 6 cm yr−1 between the two units, trigger a more vigorous mantle flow above the oceanic slab unit than above the continental slab unit. The resulting asymmetrical sublithospheric flow shears the overriding plate in front of the tear fault, and deformation gradually switches from extension to transtension through time. The consistency between our models results and geological observations suggests that the Late Cenozoic deformation of the Aegean domain, including the formation of the North Aegean Trough and Central Hellenic Shear zone, results from the spatial variations in the buoyancy of the subducting lithosphere. In particular, the lateral changes of the subduction regime caused by the Early Pliocene subduction of the old oceanic Ionian plate redesigned mantle flow and excited an increasingly vigorous dextral shear underneath the overriding plate. The models suggest that it is the inception of the Kefalonia Fault that caused the transition between an extension dominated tectonic regime to transtension, in the North Aegean, Mainland Greece and Peloponnese. The subduction of the tear fault may also have helped the propagation of the North Anatolian Fault into the Aegean domain.
Hidden Degeneracies in Piecewise Smooth Dynamical Systems
Jeffrey, Mike R.
When a flow suffers a discontinuity in its vector field at some switching surface, the flow can cross through or slide along the surface. Sliding along the switching surface can be understood as the flow along an invariant manifold inside a switching layer. It turns out that the usual method for finding sliding modes — the Filippov convex combination or Utkin equivalent control — results in a degeneracy in the switching layer whenever the flow is tangent to the switching surface from both sides. We derive the general result and analyze the simplest case here, where the flow curves parabolically on either side of the switching surface (the so-called fold-fold or two-fold singularities). The result is a set of zeros of the fast switching flow inside the layer, which is structurally unstable to perturbation by terms nonlinear in the switching parameter, terms such as (signx)2 [where the superscript does mean “squared”]. We provide structurally stable forms, and show that in this form the layer system is equivalent to a generic singularity of a two timescale system. Finally we show that the same degeneracy arises when a discontinuity is smoothed using standard regularization methods.
Nonintentional behavioural responses to psi : hidden targets and hidden observers
Anderson, Mary-Jane Charlotte
2012-01-01
Psi is the phenomenon of apparently responding to or receiving information by means other than the recognised senses. Psi information may influence human behaviour, without the individual intending this or even being aware of it. This thesis seeks to investigate nonintentional behavioural responses to psi. We present five empirical studies that investigated nonintentional behavioural responses to psi information. In each study, the psi information was hidden from participants, ...
Nuclear scissors modes and hidden angular momenta
Balbutsev, E B; Schuck, P
2016-01-01
The coupled dynamics of low lying modes and various giant resonances are studied with the help of the Wigner Function Moments method generalized to take into account spin degrees of freedom and pair correlations simultaneously. The method is based on Time Dependent Hartree-Fock-Bogoliubov equations. The model of the harmonic oscillator including spin-orbit potential plus quadrupole-quadrupole and spin-spin interactions is considered. New low lying spin dependent modes are analyzed. Special attention is paid to the scissors modes. A new source of nuclear magnetism, connected with counter-rotation of spins up and down around the symmetry axis (hidden angular momenta), is discovered. Its inclusion into the theory allows one to improve substantially the agreement with experimental data in the description of energies and transition probabilities of scissors modes.
Itter, Malcolm S; Finley, Andrew O; D'Amato, Anthony W; Foster, Jane R; Bradford, John B
2017-06-01
Changes in the frequency, duration, and severity of climate extremes are forecast to occur under global climate change. The impacts of climate extremes on forest productivity and health remain difficult to predict due to potential interactions with disturbance events and forest dynamics-changes in forest stand composition, density, size and age structure over time. Such interactions may lead to non-linear forest growth responses to climate involving thresholds and lag effects. Understanding how forest dynamics influence growth responses to climate is particularly important given stand structure and composition can be modified through management to increase forest resistance and resilience to climate change. To inform such adaptive management, we develop a hierarchical Bayesian state space model in which climate effects on tree growth are allowed to vary over time and in relation to past climate extremes, disturbance events, and forest dynamics. The model is an important step toward integrating disturbance and forest dynamics into predictions of forest growth responses to climate extremes. We apply the model to a dendrochronology data set from forest stands of varying composition, structure, and development stage in northeastern Minnesota that have experienced extreme climate years and forest tent caterpillar defoliation events. Mean forest growth was most sensitive to water balance variables representing climatic water deficit. Forest growth responses to water deficit were partitioned into responses driven by climatic threshold exceedances and interactions with insect defoliation. Forest growth was both resistant and resilient to climate extremes with the majority of forest growth responses occurring after multiple climatic threshold exceedances across seasons and years. Interactions between climate and disturbance were observed in a subset of years with insect defoliation increasing forest growth sensitivity to water availability. Forest growth was particularly
Institute of Scientific and Technical Information of China (English)
李仁杰; 刘洋; 等
2002-01-01
We present a general approach to the construction of conservation laws for variable mass noholonmic nonconservative systems.First,we give the definition of integrating factors,and we study in detail the necessary conditions for the existence of the conserved quantities,Then,we establish the conservatioin theorem and its inverse theorem for Hamilton's canonical equations of motion of variable mass nonholonomic nonocnservative dynamical systems.Finally,we give an example to illustrate the application of the results.
Institute of Scientific and Technical Information of China (English)
李仁杰; 乔永芬; 刘洋
2002-01-01
We present a general approach to the construction of conservation laws for variable mass nonholonomic noncon-servative systems. First, we give the definition of integrating factors, and we study in detail the necessary conditionsfor the existence of the conserved quantities. Then, we establish the conservation theorem and its inverse theorem forHamilton's canonical equations of motion of variable mass nonholonomic nonconservative dynamical systems. Finally,we give an example to illustrate the application of the results.
Constable, Andrew J.; Costa, Daniel P.; Schofield, Oscar; Newman, Louise; Urban, Edward R.; Fulton, Elizabeth A.; Melbourne-Thomas, Jessica; Ballerini, Tosca; Boyd, Philip W.; Brandt, Angelika; de la Mare, Willaim K.; Edwards, Martin; Eléaume, Marc; Emmerson, Louise; Fennel, Katja; Fielding, Sophie; Griffiths, Huw; Gutt, Julian; Hindell, Mark A.; Hofmann, Eileen E.; Jennings, Simon; La, Hyoung Sul; McCurdy, Andrea; Mitchell, B. Greg; Moltmann, Tim; Muelbert, Monica; Murphy, Eugene; Press, Anthony J.; Raymond, Ben; Reid, Keith; Reiss, Christian; Rice, Jake; Salter, Ian; Smith, David C.; Song, Sun; Southwell, Colin; Swadling, Kerrie M.; Van de Putte, Anton; Willis, Zdenka
2016-09-01
Reliable statements about variability and change in marine ecosystems and their underlying causes are needed to report on their status and to guide management. Here we use the Framework on Ocean Observing (FOO) to begin developing ecosystem Essential Ocean Variables (eEOVs) for the Southern Ocean Observing System (SOOS). An eEOV is a defined biological or ecological quantity, which is derived from field observations, and which contributes significantly to assessments of Southern Ocean ecosystems. Here, assessments are concerned with estimating status and trends in ecosystem properties, attribution of trends to causes, and predicting future trajectories. eEOVs should be feasible to collect at appropriate spatial and temporal scales and are useful to the extent that they contribute to direct estimation of trends and/or attribution, and/or development of ecological (statistical or simulation) models to support assessments. In this paper we outline the rationale, including establishing a set of criteria, for selecting eEOVs for the SOOS and develop a list of candidate eEOVs for further evaluation. Other than habitat variables, nine types of eEOVs for Southern Ocean taxa are identified within three classes: state (magnitude, genetic/species, size spectrum), predator-prey (diet, foraging range), and autecology (phenology, reproductive rate, individual growth rate, detritus). Most candidates for the suite of Southern Ocean taxa relate to state or diet. Candidate autecological eEOVs have not been developed other than for marine mammals and birds. We consider some of the spatial and temporal issues that will influence the adoption and use of eEOVs in an observing system in the Southern Ocean, noting that existing operations and platforms potentially provide coverage of the four main sectors of the region - the East and West Pacific, Atlantic and Indian. Lastly, we discuss the importance of simulation modelling in helping with the design of the observing system in the long
Dysonian dynamics of the Ginibre ensemble.
Burda, Zdzislaw; Grela, Jacek; Nowak, Maciej A; Tarnowski, Wojciech; Warchoł, Piotr
2014-09-05
We study the time evolution of Ginibre matrices whose elements undergo Brownian motion. The non-Hermitian character of the Ginibre ensemble binds the dynamics of eigenvalues to the evolution of eigenvectors in a nontrivial way, leading to a system of coupled nonlinear equations resembling those for turbulent systems. We formulate a mathematical framework allowing simultaneous description of the flow of eigenvalues and eigenvectors, and we unravel a hidden dynamics as a function of a new complex variable, which in the standard description is treated as a regulator only. We solve the evolution equations for large matrices and demonstrate that the nonanalytic behavior of the Green's functions is associated with a shock wave stemming from a Burgers-like equation describing correlations of eigenvectors. We conjecture that the hidden dynamics that we observe for the Ginibre ensemble is a general feature of non-Hermitian random matrix models and is relevant to related physical applications.
Penta-Quark States with Strangeness, Hidden Charm and Beauty
Wu, Jia-Jun; Zou, Bing-Song
The classical quenched quark models with three constituent quarks provide a good description for the baryon spatial ground states, but fail to reproduce the spectrum of baryon excited states. More and more evidences suggest that unquenched effects with multi-quark dynamics are necessary ingredients to solve the problem. Several new hyperon resonances reported recently could fit in the picture of penta-quark states. Based on this picture, some new hyperon excited states were predicted to exist; meanwhile with extension from strangeness to charm and beauty, super-heavy narrow N* and Λ* resonances with hidden charm or beauty were predicted to be around 4.3 and 11 GeV, respectively. Recently, two of such N* with hidden charm might have been observed by the LHCb experiment. More of those states are expected to be observed in near future. This opens a new window in order to study hadronic dynamics for the multi-quark states.
Penta-quark States with Strangeness, Hidden Charm and Beauty
Wu, Jia-Jun
2015-01-01
The classical quenched quark models with three constituent quarks provide a good description for the baryon spatial ground states, but fail to reproduce the spectrum of baryon excited states. More and more evidences suggest that unquenched effects with multi-quark dynamics are necessary ingredients to solve the problem. Several new hyperon resonances reported recently could fit in the picture of penta-quark states. Based on this picture, some new hyperon excited states were predicted to exist; meanwhile with extension from strangeness to charm and beauty, super-heavy narrow $N^*$ and $\\Lambda^*$ resonances with hidden charm or beauty were predicted to be around 4.3 and 11 GeV, respectively. Recently, two of such $N^*$ with hidden charm might have been observed by the LHCb experiment. More of those states are expected to be observed in near future. This opens a new window in order to study hadronic dynamics for the multi-quark states.
Directory of Open Access Journals (Sweden)
Marina Cavalcanti Jales
2015-12-01
Full Text Available Abstract The Rocas Atoll Biological Reserve is located in the Atlantic Ocean, at 3º 51' S and 33º 49' W. It lies 143 nautical miles from the City of Natal, Rio Grande do Norte (Brazil. The purpose of this study was to analyze the hydrology, water masses, currents and chlorophyll a content to determine the dynamics of phytoplankton biomass around the Rocas Atoll. Samples were collected in July 2010 in the area around the Atoll, using the Research Vessel Cruzeiro do Sul of the Brazilian Navy. Two transects were established according to the surface currents, one of which at the southeast of the Atoll (SE and the other at norwest (NW. Three collection points were determined on each of these transects. Samples were collected at different depths (surface and DCM - Deep Chlorophyll Maximum and different times (day and night. According to PCA (Principal Component Analysis, the nutrients analyzed, DIN (dissolved inorganic nitrogen, DIP (dissolved inorganic phosphorus and silicate, were inversely correlated with temperature and dissolved oxygen. Most environmental variables showed a significant increase due to the turbulence on the Northwest transect. There was an increase in the concentration of chlorophyll a and nutrients when the temperature and oxygen in the mixed layer was reduced due to the influence of the SACW (South Atlantic Central Water. Despite the increase observed in some variables such as nutrient salts and chlorophyll a, the temperature in the mixed layer attained a mean value of 23.23 ºC due to the predominance of Tropical Water. The increase of the phytoplankton biomass on the NW transect was, therefore, caused by the "island effect" and not by upwelling.
Hydrologic and light variability as drivers of stream biofilm-invertebrate dynamics
Ceola, Serena; Bertuzzo, Enrico; Mari, Lorenzo; Botter, Gianluca; Hödl, Iris; Battin, Tom; Gatto, Marino; Montanari, Alberto; Rinaldo, Andrea
2013-04-01
Among all abiotic controlling factors, hydrology and light availability are the key drivers that influence and affect space and time organization, structure and function of stream ecosystems. To analyze from both an experimental and a modeling perspective the coupled effect of light and flow variability on the interactions between stream biofilm (i.e. the main component of benthic algae) and macroinvertebrates, a flume experiment and a modeling analysis have been carried out. In order to explore the impacts of flow alterations, two alternative discharge regimes have been performed, mainly a stochastic time-varying and a constant discharge sequence, reproducing the natural streamflow fluctuations of a river and an anthropogenic flow modification, respectively. In addition, given that light availability typically changes along the fluvial continuum as a function of the vegetation coverage and consequently affects biofilm primary production and macroinvertebrate foraging activity, four different light treatments characterized by 90%, 65%, 50% and 27% transmission of incident light radiation, have been introduced. Average grazing activity was significantly enhanced under variable flow conditions and highest at intermediate light availability. These results suggest that stochastic flow regime offers increased opportunity for grazing under favorable shear stress conditions, with implications for trophic carbon transfer in stream food webs. Alterations of natural streamflow regimes may have severe effects on the structure and function of stream ecosystems. Indeed future environmental impact criteria should include assessments of impacts on ecosystem processes. Our experimental evidence reveals hitherto unknown effects of flow regime changes on ecosystem functioning, and suggests that alterations simply maintaining minimum flowrates are inadequate to fully preserve ecosystem integrity. In addition, the results of a modeling analysis of the observed biofilm
Itter, Malcolm S.; Finley, Andrew O.; D'Amato, Anthony W.; Foster, Jane R.; Bradford, John B.
2017-01-01
Changes in the frequency, duration, and severity of climate extremes are forecast to occur under global climate change. The impacts of climate extremes on forest productivity and health remain difficult to predict due to potential interactions with disturbance events and forest dynamics—changes in forest stand composition, density, size and age structure over time. Such interactions may lead to non-linear forest growth responses to climate involving thresholds and lag effects. Understanding how forest dynamics influence growth responses to climate is particularly important given stand structure and composition can be modified through management to increase forest resistance and resilience to climate change. To inform such adaptive management, we develop a hierarchical Bayesian state space model in which climate effects on tree growth are allowed to vary over time and in relation to past climate extremes, disturbance events, and forest dynamics. The model is an important step toward integrating disturbance and forest dynamics into predictions of forest growth responses to climate extremes. We apply the model to a dendrochronology data set from forest stands of varying composition, structure, and development stage in northeastern Minnesota that have experienced extreme climate years and forest tent caterpillar defoliation events. Mean forest growth was most sensitive to water balance variables representing climatic water deficit. Forest growth responses to water deficit were partitioned into responses driven by climatic threshold exceedances and interactions with insect defoliation. Forest growth was both resistant and resilient to climate extremes with the majority of forest growth responses occurring after multiple climatic threshold exceedances across seasons and years. Interactions between climate and disturbance were observed in a subset of years with insect defoliation increasing forest growth sensitivity to water availability. Forest growth was particularly
Robustness of MEK-ERK Dynamics and Origins of Cell-to-Cell Variability in MAPK Signaling
Directory of Open Access Journals (Sweden)
Sarah Filippi
2016-06-01
Full Text Available Cellular signaling processes can exhibit pronounced cell-to-cell variability in genetically identical cells. This affects how individual cells respond differentially to the same environmental stimulus. However, the origins of cell-to-cell variability in cellular signaling systems remain poorly understood. Here, we measure the dynamics of phosphorylated MEK and ERK across cell populations and quantify the levels of population heterogeneity over time using high-throughput image cytometry. We use a statistical modeling framework to show that extrinsic noise, particularly that from upstream MEK, is the dominant factor causing cell-to-cell variability in ERK phosphorylation, rather than stochasticity in the phosphorylation/dephosphorylation of ERK. We furthermore show that without extrinsic noise in the core module, variable (including noisy signals would be faithfully reproduced downstream, but the within-module extrinsic variability distorts these signals and leads to a drastic reduction in the mutual information between incoming signal and ERK activity.
Bagheri, Pedram; Sun, Qiao
2016-07-01
In this paper, a novel synthesis of Nussbaum-type functions, and an adaptive radial-basis function neural network is proposed to design controllers for variable-speed, variable-pitch wind turbines. Dynamic equations of the wind turbine are highly nonlinear, uncertain, and affected by unknown disturbance sources. Furthermore, the dynamic equations are non-affine with respect to the pitch angle, which is a control input. To address these problems, a Nussbaum-type function, along with a dynamic control law are adopted to resolve the non-affine nature of the equations. Moreover, an adaptive radial-basis function neural network is designed to approximate non-parametric uncertainties. Further, the closed-loop system is made robust to unknown disturbance sources, where no prior knowledge of disturbance bound is assumed in advance. Finally, the Lyapunov stability analysis is conducted to show the stability of the entire closed-loop system. In order to verify analytical results, a simulation is presented and the results are compared to both a PI and an existing adaptive controllers.
A Stochastic Fractional Dynamics Model of Space-time Variability of Rain
Kundu, Prasun K.; Travis, James E.
2013-01-01
Rainfall varies in space and time in a highly irregular manner and is described naturally in terms of a stochastic process. A characteristic feature of rainfall statistics is that they depend strongly on the space-time scales over which rain data are averaged. A spectral model of precipitation has been developed based on a stochastic differential equation of fractional order for the point rain rate, that allows a concise description of the second moment statistics of rain at any prescribed space-time averaging scale. The model is thus capable of providing a unified description of the statistics of both radar and rain gauge data. The underlying dynamical equation can be expressed in terms of space-time derivatives of fractional orders that are adjusted together with other model parameters to fit the data. The form of the resulting spectrum gives the model adequate flexibility to capture the subtle interplay between the spatial and temporal scales of variability of rain but strongly constrains the predicted statistical behavior as a function of the averaging length and times scales. We test the model with radar and gauge data collected contemporaneously at the NASA TRMM ground validation sites located near Melbourne, Florida and in Kwajalein Atoll, Marshall Islands in the tropical Pacific. We estimate the parameters by tuning them to the second moment statistics of radar data. The model predictions are then found to fit the second moment statistics of the gauge data reasonably well without any further adjustment.
Transient and dynamic control of a variable speed wind turbine with synchronous generator
Energy Technology Data Exchange (ETDEWEB)
Jauch, Clemens [Riso National Laboratory, Wind Energy Department, PO Box 49, DK 4000 Roskilde, (Denmark)
2007-02-14
In this article, a controller for dynamic and transient control of a variable speed wind turbine with a full-scale converter-connected high-speed synchronous generator is presented. First, the phenomenon of drive train oscillations in wind turbines with full-scale converter-connected generators is discussed. Based on this discussion, a controller is presented that dampens these oscillations without impacting on the power that the wind turbine injects into the grid. Since wind turbines are increasingly demanded to take over power system stabilizing and control tasks, the presented wind turbine design is further enhanced to support the grid in transient grid events. A controller is designed that allows the wind turbine to ride through transient grid faults. Since such faults often cause power system oscillations, another controller is added that enables the turbine to participate in the damping of such oscillations. It is concluded that the controllers presented keep the wind turbine stable under any operating conditions, and that they are capable of adding substantial damping to the power system. (Author).
Carranza, Juan; Polo, Vicente
2015-07-01
While sex can be advantageous for a lineage in the long term, we still lack an explanation for its maintenance with the twofold cost per generation. Here we model an infinite diploid population where two autosomal loci determine, respectively, the reproductive mode, sexual versus asexual and the mating system, polygynous (costly sex) versus monogamous (assuming equal contribution of parents to offspring, i.e. non-costly sex). We show that alleles for costly sex can spread when non-costly sexual modes buffer the interaction between asexual and costly sexual strategies, even without twofold benefit of recombination with respect to asexuality. The three interacting strategies have intransitive fitness relationships leading to a rock-paper-scissors dynamics, so that alleles for costly sex cannot be eliminated by asexuals in most situations throughout the parameter space. Our results indicate that sexual lineages with variable mating systems can resist the invasion of asexuals and allow for long-term effects to accumulate, thus providing a solution to the persisting theoretical question of why sex was not displaced by asexuality along evolution.
Carranza, Juan; Polo, Vicente
2015-01-01
While sex can be advantageous for a lineage in the long term, we still lack an explanation for its maintenance with the twofold cost per generation. Here we model an infinite diploid population where two autosomal loci determine, respectively, the reproductive mode, sexual versus asexual and the mating system, polygynous (costly sex) versus monogamous (assuming equal contribution of parents to offspring, i.e. non-costly sex). We show that alleles for costly sex can spread when non-costly sexual modes buffer the interaction between asexual and costly sexual strategies, even without twofold benefit of recombination with respect to asexuality. The three interacting strategies have intransitive fitness relationships leading to a rock–paper–scissors dynamics, so that alleles for costly sex cannot be eliminated by asexuals in most situations throughout the parameter space. Our results indicate that sexual lineages with variable mating systems can resist the invasion of asexuals and allow for long-term effects to accumulate, thus providing a solution to the persisting theoretical question of why sex was not displaced by asexuality along evolution. PMID:26587254
Fischer, Sylvia; Schweigmann, Nicolás
2004-12-01
The study was conducted in a park of Buenos Aires City, where a total of 89 rain pools were sampled weekly for mosquito immature stages over a one-year period. The aim of the present paper was to investigate the seasonal dynamics of three Culex species breeding in temporary rain pools and to analyze the relationships of the presence of these species to pool dimensions, pool age, vegetation, and insolation degree. The three species showed differences in their seasonal patterns, Culex dolosus being present during the whole year, Culex pipiens mainly in the summer season, and Culex maxi almost exclusively during the fall. The variable explaining most of the variation among sampling dates in species composition was weekly mean temperature. A significant positive association was detected among mosquito species, as they were recorded together more frequently than expected by chance. The statistical analyses performed revealed significant positive relationships of all three mosquito species to increasing surface area, whereas no relationship to insolation degree was detected in the studied pools. Culex pipiens and Culex dolosus showed positive relationships to increasing vegetation cover, whereas the presence of Culex dolosus was also related to pool age.
Hidalgo-Gato, Rafael A Valls
2012-01-01
From a rigorous historic analysis of 1686 I. Newton and 1905 A. Einstein works where the last derived the universal mass-energy relationship, it is concluded that rest mass measures potential energy. From the same formula used to obtain that relation, it is derived the ratio Total Energy/Potential Energy is equal to the gamma relativistic factor. It is derived a formula for the variation of a body rest mass with its position in a gravity field, explaining with it the behavior of an atomic clock. It is revised the bodies free fall in a gravitational field, finding that a constant total mass is equal to the gravitational mass, while the variable rest mass is equal to the inertial mass, maintaining all an identical behavior independent of their masses. A revision of the E\\"otv\\"os experiment concludes that it is unable to detect the found difference between inertial and gravitational mass. Applying the extended 1905 relativistic dynamics to Mercury, its perihelion shift is determined; it is concluded with the co...
Utilizing multiple state variables to improve the dynamic range of analog switching in a memristor
Energy Technology Data Exchange (ETDEWEB)
Jeong, YeonJoo; Kim, Sungho; Lu, Wei D., E-mail: wluee@eecs.umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, 48109 (United States)
2015-10-26
Memristors and memristive systems have been extensively studied for data storage and computing applications such as neuromorphic systems. To act as synapses in neuromorphic systems, the memristor needs to exhibit analog resistive switching (RS) behavior with incremental conductance change. In this study, we show that the dynamic range of the analog RS behavior can be significantly enhanced in a tantalum-oxide-based memristor. By controlling different state variables enabled by different physical effects during the RS process, the gradual filament expansion stage can be selectively enhanced without strongly affecting the abrupt filament length growth stage. Detailed physics-based modeling further verified the observed experimental effects and revealed the roles of oxygen vacancy drift and diffusion processes, and how the diffusion process can be selectively enhanced during the filament expansion stage. These findings lead to more desirable and reliable memristor behaviors for analog computing applications. Additionally, the ability to selectively control different internal physical processes demonstrated in the current study provides guidance for continued device optimization of memristor devices in general.
Dynamical masses of a nova-like variable on the edge of the period gap
Rodríguez-Gil, P; Marsh, T R; Gänsicke, B T; Steeghs, D; Long, K S; Martínez-Pais, I G; Padilla, M Armas; Schwarz, R; Schreiber, M R; Torres, M A P; Koester, D; Dhillon, V S; Castellano, J; Rodríguez, D
2015-01-01
We present the first dynamical determination of the binary parameters of an eclipsing SW Sextantis star in the 3-4 hour orbital period range during a low state. We obtained time-resolved optical spectroscopy and photometry of HS 0220+0603 during its 2004-2005 low brightness state, as revealed in the combined SMARTS, IAC80 and M1 Group long-term optical light curve. The optical spectra taken during primary eclipse reveal a secondary star spectral type of M5.5 $\\pm$ 0.5 as derived from molecular band-head indices. The spectra also provide the first detection of a DAB white dwarf in a cataclysmic variable. By modelling its optical spectrum we estimate a white dwarf temperature of 30000 $\\pm$ 5000 K. By combining the results of modelling the white dwarf eclipse from ULTRACAM light curves with those obtained by simultaneously fitting the emission- and absorption-line radial velocity curves and I-band ellipsoidal light curves, we measure the stellar masses to be M$_1 = 0.87 \\pm 0.09$ M$_\\odot$ and M$_2 = 0.47 \\pm 0...
Fan, Hui Ching; Yan, Hong Sen
2012-03-01
Without modifying the cam contour, a cam mechanism with a variable input speed trajectory offers an alternative solution to flexibly achieve kinematic and dynamic characteristics, and then decrease the follower's residual vibration. Firstly, the speed trajectory of cam is derived by employing Bezier curve, and motion continuity conditions are investigated. Then the motion characteristics between the plate cam and its roller follower are derived. To analyze the residual vibration, a single degree of freedom dynamic model of the elastic cam-follower system is introduced. Based on the motion equation derived from the dynamic model, the residual vibration of the follower is yielded. The design procedure to improve the kinematic and dynamic motion characteristics is presented and two design examples with discussions are provided. Finally, the simulations of the kinematic and dynamic models by ADAMS are carried out and verified that the design models as well as the performances of the mechanism are feasible.
Anelone, Anet J N; Spurgeon, Sarah K
2016-01-01
Experimental and mathematical studies in immunology have revealed that the dynamics of the programmed T cell response to vigorous infection can be conveniently modelled using a sigmoidal or a discontinuous immune response function. This paper hypothesizes strong synergies between this existing work and the dynamical behaviour of engineering systems with a variable structure control (VSC) law. These findings motivate the interpretation of the immune system as a variable structure control system. It is shown that dynamical properties as well as conditions to analytically assess the transition from health to disease can be developed for the specific T cell response from the theory of variable structure control. In particular, it is shown that the robustness properties of the specific T cell response as observed in experiments can be explained analytically using a VSC perspective. Further, the predictive capacity of the VSC framework to determine the T cell help required to overcome chronic Lymphocytic Choriomeningitis Virus (LCMV) infection is demonstrated. The findings demonstrate that studying the immune system using variable structure control theory provides a new framework for evaluating immunological dynamics and experimental observations. A modelling and simulation tool results with predictive capacity to determine how to modify the immune response to achieve healthy outcomes which may have application in drug development and vaccine design.
Takahashi, Makoto; Nakamoto, Tomoko; Matsukawa, Kanji; Ishii, Kei; Watanabe, Tae; Sekikawa, Kiyokazu; Hamada, Hironobu
2016-03-01
What is the central question of this study? Should we use the high-frequency (HF) component of P-P interval as an index of cardiac parasympathetic nerve activity during moderate exercise? What is the main finding and its importance? The HF component of P-P interval variability remained even at a heart rate of 120-140 beats min(-1) and was further reduced by atropine, indicating incomplete cardiac vagal withdrawal during moderate exercise. The HF component of R-R interval is invalid as an estimate of cardiac parasympathetic outflow during moderate exercise; instead, the HF component of P-P interval variability should be used. The high-frequency (HF) component of R-R interval variability has been widely used as an indirect estimate of cardiac parasympathetic (vagal) outflow to the sino-atrial node of the heart. However, we have recently found that the variability of the R-R interval becomes much smaller during dynamic exercise than that of the P-P interval above a heart rate (HR) of ∼100 beats min(-1). We hypothesized that cardiac parasympathetic outflow during dynamic exercise with a higher intensity may be better estimated using the HF component of P-P interval variability. To test this hypothesis, the HF components of both P-P and R-R interval variability were analysed using a Wavelet transform during dynamic exercise. Twelve subjects performed ergometer exercise to increase HR from the baseline of 69 ± 3 beats min(-1) to three different levels of 100, 120 and 140 beats min(-1). We also examined the effect of atropine sulfate on the HF components in eight of the 12 subjects during exercise at an HR of 140 beats min(-1) . The HF component of P-P interval variability was significantly greater than that of R-R interval variability during exercise, especially at the HRs of 120 and 140 beats min(-1). The HF component of P-P interval variability was more reduced by atropine than that of R-R interval variability. We conclude that cardiac parasympathetic outflow to the
Sardeshmukh, P.
2002-12-01
formula are obtained empirically from a separate dry linear Primitive Equation (PE) model forced by steady idealized diabatic heating. The ability of this dynamical coupling formula to determine local vertical velocities from the history of local diabatic heating rates is tested in a linear PE model forced by oscillating 3-dimensional heating fields. The formula works surprisingly well over a wide range of spatial and temporal heating scales, even passing the hard test of correctly reproducing the phase shift and amplication of the response for near-resonant heating. This success suggests that to obtain the correct advective tendencies, detailed knowledge of the vertical and temporal structure of the diabatic forcing is necessary, but that of its horizontal structure is not. The single column model with vertical velocities coupled to the local temperature and humidity in this manner effectively eliminates the spurious SCM instabilities alluded to above. Such a dynamically interactive SCM would be useful in increasing the realism of simple "Box"-type models of regional climate variability. It is also argued that future SCM diagnoses of GCM physics would benefit from such a coupling.
Waldron, S.; Coleman, M.; Scott, E. M.; Drew, S.
2013-12-01
[DOC] range of 8 - 55.6 mg/l C, with the greatest shift in a single day being 23.5 mg/l C. We will present this highly dynamic [DOC] time series and also contemporaneous data from an in-situ water chemistry sonde profiling other measures of the ';riverine circulation system': pH, conductivity, temperature and stage height. The challenge now is how to allow data series of ~17,500 measurements per annum to interact to better understand and model drivers of carbon export. We are exploring the application of wavelet analysis to identify periods of coherence between [DOC] and these other variables. Our initial results indicate show that coherence with [DOC] can be intermittent and irregular, and so the challenge sensor technology presents continues.
On quantum algorithms for noncommutative hidden subgroups
Energy Technology Data Exchange (ETDEWEB)
Ettinger, M. [Los Alamos National Lab., NM (United States); Hoeyer, P. [Odense Univ. (Denmark)
1998-12-01
Quantum algorithms for factoring and discrete logarithm have previously been generalized to finding hidden subgroups of finite Abelian groups. This paper explores the possibility of extending this general viewpoint to finding hidden subgroups of noncommutative groups. The authors present a quantum algorithm for the special case of dihedral groups which determines the hidden subgroup in a linear number of calls to the input function. They also explore the difficulties of developing an algorithm to process the data to explicitly calculate a generating set for the subgroup. A general framework for the noncommutative hidden subgroup problem is discussed and they indicate future research directions.
Directory of Open Access Journals (Sweden)
Rodrigo Wiff
2012-03-01
Full Text Available Alfonsino (Beryx splendens is a species associated with seamounts, with an important fishery in Juan Fernandez archipelago, Chile (33°40'S, 79°00'W. Since 2004, this resource has been managed by catch quotas estimated from stock assessment models. The alfonsino model involves high levels of uncertainty for several reasons including a lack of knowledge of aspects of the population dynamics and poorly informative time-series that feed the proposed evaluation models. This work evaluated three hypotheses regarding population dynamics and their influence on the main state variables (biomass, recruitment of the model using age-structured and dynamic biomass models. The hypotheses corresponded to de-recruitment of older individuals, non-linearity between standardized catch per unit effort, and population abundance as well as variations of the relative importance of length structures. According to the results, the depletion of the spawning biomass between 1998 and 2008 varied between 9 and 56%, depending on the combination of hypotheses used in the model. This indicates that state variables in alfonsino are not robust to the available information; rather, they depend strongly on the hypothesis of population dynamics. The discussion is focused on interpreting the causes of the changes in the state variables in light of a conceptual model for population dynamics in alfonsino and which pieces of information would be necessary to reduce the associated uncertainty.El alfonsino (Beryx splendens es una especie asociada a montes submarinos. En Chile sustenta una importante pesquería en el archipiélago de Juan Fernández (33°40'S, 79°00'W. Desde el año 2004, este recurso es administrado a través de cuotas anuales de capturas, las cuales son estimadas desde un modelo de evaluación de stock. La modelación de la población de alfonsino se caracteriza por una alta incertidumbre, debido a diversas fuentes, como son desconocimiento de aspectos de su din
DeSmidt, Hans A.; Smith, Edward C.; Bill, Robert C.; Wang, Kon-Well
2013-01-01
This project develops comprehensive modeling and simulation tools for analysis of variable rotor speed helicopter propulsion system dynamics. The Comprehensive Variable-Speed Rotorcraft Propulsion Modeling (CVSRPM) tool developed in this research is used to investigate coupled rotor/engine/fuel control/gearbox/shaft/clutch/flight control system dynamic interactions for several variable rotor speed mission scenarios. In this investigation, a prototypical two-speed Dual-Clutch Transmission (DCT) is proposed and designed to achieve 50 percent rotor speed variation. The comprehensive modeling tool developed in this study is utilized to analyze the two-speed shift response of both a conventional single rotor helicopter and a tiltrotor drive system. In the tiltrotor system, both a Parallel Shift Control (PSC) strategy and a Sequential Shift Control (SSC) strategy for constant and variable forward speed mission profiles are analyzed. Under the PSC strategy, selecting clutch shift-rate results in a design tradeoff between transient engine surge margins and clutch frictional power dissipation. In the case of SSC, clutch power dissipation is drastically reduced in exchange for the necessity to disengage one engine at a time which requires a multi-DCT drive system topology. In addition to comprehensive simulations, several sections are dedicated to detailed analysis of driveline subsystem components under variable speed operation. In particular an aeroelastic simulation of a stiff in-plane rotor using nonlinear quasi-steady blade element theory was conducted to investigate variable speed rotor dynamics. It was found that 2/rev and 4/rev flap and lag vibrations were significant during resonance crossings with 4/rev lagwise loads being directly transferred into drive-system torque disturbances. To capture the clutch engagement dynamics, a nonlinear stick-slip clutch torque model is developed. Also, a transient gas-turbine engine model based on first principles mean
Directory of Open Access Journals (Sweden)
Trevor G. Jones
2015-08-01
Full Text Available Mangroves are found throughout the tropics, providing critical ecosystem goods and services to coastal communities and supporting rich biodiversity. Globally, mangroves are being rapidly degraded and deforested at rates exceeding loss in many tropical inland forests. Madagascar contains around 2% of the global distribution, >20% of which has been deforested since 1990, primarily from over-harvest for forest products and conversion for agriculture and aquaculture. While historically not prominent, mangrove loss in Madagascar’s Mahajamba Bay is increasing. Here, we focus on Mahajamba Bay, presenting long-term dynamics calculated using United States Geological Survey (USGS national-level mangrove maps contextualized with socio-economic research and ground observations, and the results of contemporary (circa 2011 mapping of dominant mangrove types. The analysis of the USGS data indicated 1050 hectares (3.8% lost from 2000 to 2010, which socio-economic research suggests is increasingly driven by commercial timber extraction. Contemporary mapping results permitted stratified sampling based on spectrally distinct and ecologically meaningful mangrove types, allowing for the first-ever vegetation carbon stock estimates for Mahajamba Bay. The overall mean carbon stock across all mangrove classes was estimated to be 100.97 ± 10.49 Mg C ha−1. High stature closed-canopy mangroves had the highest average carbon stock estimate (i.e., 166.82 ± 15.28 Mg C ha−1. These estimates are comparable to other published values in Madagascar and elsewhere in the Western Indian Ocean and demonstrate the ecological variability of Mahajamba Bay’s mangroves and their value towards climate change mitigation.
Directory of Open Access Journals (Sweden)
Fischer Sylvia
2002-01-01
Full Text Available The immature stages of Ochlerotatus albifasciatus develop in temporary pools. The present study aims at evaluating the seasonal dynamics of the aquatic stages of this mosquito, also analyzing the relationship among their presence and breeding success to some relevant climatic and environmental variables in the ephemeral rain pools of an urban park. Nineteen cohorts of O. albifasciatus that developed synchronously after rain events were recorded in all seasons. The proportions of mosquito-positive pools were significantly higher during the fall-winter period than in the spring-summer months (p < 0.001. The presence of this mosquito species was positively related to the amount of rain (p < 0.001, whereas negatively correlated to air temperature (p < 0.05 within a 5.2 to 29.7ºC range. The distribution of the number of cohorts per pool throughout the year was grouped (variance/mean: 3.96, indicating that these habitats were not equally suitable as breeding sites. The immature stages of O. albifasciatus were detected in pools belonging to all of the categories of surface area, depth, duration, vegetation cover, and insolation. However, the proportion of pools where immature mosquitoes were detected was positively and significantly related to surface, depth, duration, and vegetation cover. On the other hand, the proportion of mosquito-positive pools was higher at an intermediate insolation degree. Our results suggest that although preimaginal stages were present in all seasons, high temperatures may be unfavorable to larval development, and substrate vegetation may regulate water temperature. The positive relationship between the proportion of mosquito-positive pools and pool size and duration might reflect a strategy of O. albifasciatus to accomplish immature development.
Modeling Food Delivery Dynamics For Juvenile Salmonids Under Variable Flow Regimes
Harrison, L.; Utz, R.; Anderson, K.; Nisbet, R.
2010-12-01
Traditional approaches for assessing instream flow needs for salmonids have typically focused on the importance of physical habitat in determining fish habitat selection. This somewhat simplistic approach does not account for differences in food delivery rates to salmonids that arise due to spatial variability in river morphology, hydraulics and temporal variations in the flow regime. Explicitly linking how changes in the flow regime influences food delivery dynamics is an important step in advancing process-based bioenergetic models that seek to predict growth rates of salmonids across various life-stages. Here we investigate how food delivery rates for juvenile salmonids vary both spatially and with flow magnitude in a meandering reach of the Merced River, CA. We utilize a two-dimensional (2D) hydrodynamic model and discrete particle tracking algorithm to simulate invertebrate drift transport rates at baseflow and a near-bankfull discharge. Modeling results indicate that at baseflow, the maximum drift density occurs in the channel thalweg, while drift densities decrease towards the channel margins due to the process of organisms settling out of the drift. During high-flow events, typical of spring dam-releases, the invertebrate drift transport pathway follows a similar trajectory along the high velocity core and the drift concentrations are greatest in the channel centerline, though the zone of invertebrate transport occupies a greater fraction of the channel width. Based on invertebrate supply rates alone, feeding juvenile salmonids would be expected to be distributed down the channel centerline where the maximum predicted food delivery rates are located in this reach. However, flow velocities in these channel sections are beyond maximum sustainable swimming speeds for most juvenile salmonids. Our preliminary findings suggest that a lack of low velocity refuge may prevent juvenile salmonids from deriving energy from the areas with maximum drift density in this
Multi-asset Black-Scholes model as a variable second class constrained dynamical system
Bustamante, M.; Contreras, M.
2016-09-01
In this paper, we study the multi-asset Black-Scholes model from a structural point of view. For this, we interpret the multi-asset Black-Scholes equation as a multidimensional Schrödinger one particle equation. The analysis of the classical Hamiltonian and Lagrangian mechanics associated with this quantum model implies that, in this system, the canonical momentums cannot always be written in terms of the velocities. This feature is a typical characteristic of the constrained system that appears in the high-energy physics. To study this model in the proper form, one must apply Dirac's method for constrained systems. The results of the Dirac's analysis indicate that in the correlation parameters space of the multi-assets model, there exists a surface (called the Kummer surface ΣK, where the determinant of the correlation matrix is null) on which the constraint number can vary. We study in detail the cases with N = 2 and N = 3 assets. For these cases, we calculate the propagator of the multi-asset Black-Scholes equation and show that inside the Kummer ΣK surface the propagator is well defined, but outside ΣK the propagator diverges and the option price is not well defined. On ΣK the propagator is obtained as a constrained path integral and their form depends on which region of the Kummer surface the correlation parameters lie. Thus, the multi-asset Black-Scholes model is an example of a variable constrained dynamical system, and it is a new and beautiful property that had not been previously observed.
Hidden Markov Models for indirect classification of occupant behaviour
DEFF Research Database (Denmark)
Liisberg, Jon Anders Reichert; Møller, Jan Kloppenborg; Bloem, H.
2016-01-01
Even for similar residential buildings, a huge variability in the energy consumption can be observed. This variability is mainly due to the different behaviours of the occupants and this impacts the thermal (temperature setting, window opening, etc.) as well as the electrical (appliances, TV....... This paper focuses on the use of Hidden Markov Models (HMMs) to create methods for indirect observations and characterisation of occupant behaviour. By applying homogeneous HMMs on the electricity consumption of fourteen apartments, three states describing the data were found suitable. The most likely...
Mayhew, S D; Bagshaw, A P
2017-07-15
Accurate characterization of the spatiotemporal relationship between two of the most prominent neuroimaging measures of neuronal activity, the 8-13Hz, occipito-parietal EEG alpha oscillation and the BOLD fMRI signal, must encompass the intrinsically dynamic nature of both alpha power and brain function. Here, during the eyes-open resting state, we use a 16s sliding-window analysis and demonstrate that the mean spatial network of dynamic alpha-BOLD correlations is highly comparable to the static network calculated over six minutes. However, alpha-BOLD correlations showed substantial spatiotemporal variability within-subjects and passed through many different configurations such that the static network was fully represented in only ~10% of 16s epochs, with visual and parietal regions (coherent on average) often opposingly correlated with each other or with alpha. We find that the common assumption of static-alpha BOLD correlations greatly oversimplifies temporal variation in brain network dynamics. Fluctuations in alpha-BOLD coupling significantly depended upon the instantaneous amplitude of alpha power, and primary and lateral visual areas were most strongly negatively correlated with alpha during different alpha power states, possibly suggesting the action of multiple alpha mechanisms. Dynamic alpha-BOLD correlations could not be explained by eye-blinks/movements, head motion or non-neuronal physiological variability. Individual's mean alpha power and frequency were found to contribute to between-subject variability in alpha-BOLD correlations. Additionally, application to a visual stimulation dataset showed that dynamic alpha-BOLD correlations provided functional information pertaining to the brain's response to stimulation by exhibiting spatiotemporal fluctuations related to variability in the trial-by-trial BOLD response magnitude. Significantly weaker visual alpha-BOLD correlations were found both preceding and following small amplitude BOLD response trials
Reduced-Rank Hidden Markov Models
Siddiqi, Sajid M; Gordon, Geoffrey J
2009-01-01
We introduce the Reduced-Rank Hidden Markov Model (RR-HMM), a generalization of HMMs that can model smooth state evolution as in Linear Dynamical Systems (LDSs) as well as non-log-concave predictive distributions as in continuous-observation HMMs. RR-HMMs assume an m-dimensional latent state and n discrete observations, with a transition matrix of rank k <= m. This implies the dynamics evolve in a k-dimensional subspace, while the shape of the set of predictive distributions is determined by m. Latent state belief is represented with a k-dimensional state vector and inference is carried out entirely in R^k, making RR-HMMs as computationally efficient as k-state HMMs yet more expressive. To learn RR-HMMs, we relax the assumptions of a recently proposed spectral learning algorithm for HMMs (Hsu, Kakade and Zhang 2009) and apply it to learn k-dimensional observable representations of rank-k RR-HMMs. The algorithm is consistent and free of local optima, and we extend its performance guarantees to cover the RR-...
Directory of Open Access Journals (Sweden)
Joachim Almquist
Full Text Available The last decade has seen a rapid development of experimental techniques that allow data collection from individual cells. These techniques have enabled the discovery and characterization of variability within a population of genetically identical cells. Nonlinear mixed effects (NLME modeling is an established framework for studying variability between individuals in a population, frequently used in pharmacokinetics and pharmacodynamics, but its potential for studies of cell-to-cell variability in molecular cell biology is yet to be exploited. Here we take advantage of this novel application of NLME modeling to study cell-to-cell variability in the dynamic behavior of the yeast transcription repressor Mig1. In particular, we investigate a recently discovered phenomenon where Mig1 during a short and transient period exits the nucleus when cells experience a shift from high to intermediate levels of extracellular glucose. A phenomenological model based on ordinary differential equations describing the transient dynamics of nuclear Mig1 is introduced, and according to the NLME methodology the parameters of this model are in turn modeled by a multivariate probability distribution. Using time-lapse microscopy data from nearly 200 cells, we estimate this parameter distribution according to the approach of maximizing the population likelihood. Based on the estimated distribution, parameter values for individual cells are furthermore characterized and the resulting Mig1 dynamics are compared to the single cell times-series data. The proposed NLME framework is also compared to the intuitive but limited standard two-stage (STS approach. We demonstrate that the latter may overestimate variabilities by up to almost five fold. Finally, Monte Carlo simulations of the inferred population model are used to predict the distribution of key characteristics of the Mig1 transient response. We find that with decreasing levels of post-shift glucose, the transient
Almquist, Joachim; Bendrioua, Loubna; Adiels, Caroline Beck; Goksör, Mattias; Hohmann, Stefan; Jirstrand, Mats
2015-01-01
The last decade has seen a rapid development of experimental techniques that allow data collection from individual cells. These techniques have enabled the discovery and characterization of variability within a population of genetically identical cells. Nonlinear mixed effects (NLME) modeling is an established framework for studying variability between individuals in a population, frequently used in pharmacokinetics and pharmacodynamics, but its potential for studies of cell-to-cell variability in molecular cell biology is yet to be exploited. Here we take advantage of this novel application of NLME modeling to study cell-to-cell variability in the dynamic behavior of the yeast transcription repressor Mig1. In particular, we investigate a recently discovered phenomenon where Mig1 during a short and transient period exits the nucleus when cells experience a shift from high to intermediate levels of extracellular glucose. A phenomenological model based on ordinary differential equations describing the transient dynamics of nuclear Mig1 is introduced, and according to the NLME methodology the parameters of this model are in turn modeled by a multivariate probability distribution. Using time-lapse microscopy data from nearly 200 cells, we estimate this parameter distribution according to the approach of maximizing the population likelihood. Based on the estimated distribution, parameter values for individual cells are furthermore characterized and the resulting Mig1 dynamics are compared to the single cell times-series data. The proposed NLME framework is also compared to the intuitive but limited standard two-stage (STS) approach. We demonstrate that the latter may overestimate variabilities by up to almost five fold. Finally, Monte Carlo simulations of the inferred population model are used to predict the distribution of key characteristics of the Mig1 transient response. We find that with decreasing levels of post-shift glucose, the transient response of Mig1 tend
Rockcastle, Siobhan
2013-01-01
Daylight is a dynamic source of illumination in architectural space, creating diverse and ephemeral configurations of light and shadow within the built environment. Perceptual qualities of daylight, such as contrast and temporal variability, are essential to our understanding of both material and visual effects in architecture. Although spatial contrast and light variability are fundamental to the visual experience of architecture, architects still rely primarily on intuition to evaluate their designs because there are few metrics that address these factors. Through an analysis of contemporary
Richard, Jacques C.
1995-01-01
This paper presents a dynamic model of an internal combustion engine coupled to a variable pitch propeller. The low-order, nonlinear time-dependent model is useful for simulating the propulsion system of general aviation single-engine light aircraft. This model is suitable for investigating engine diagnostics and monitoring and for control design and development. Furthermore, the model may be extended to provide a tool for the study of engine emissions, fuel economy, component effects, alternative fuels, alternative engine cycles, flight simulators, sensors, and actuators. Results show that the model provides a reasonable representation of the propulsion system dynamics from zero to 10 Hertz.
Early days in complex dynamics a history of complex dynamics in one variable during 1906-1942
Alexander, Daniel S; Rosa, Alessandro
2011-01-01
The theory of complex dynamics, whose roots lie in 19th-century studies of the iteration of complex function conducted by Kœnigs, Schröder, and others, flourished remarkably during the first half of the 20th century, when many of the central ideas and techniques of the subject developed. This book by Alexander, Iavernaro, and Rosa paints a robust picture of the field of complex dynamics between 1906 and 1942 through detailed discussions of the work of Fatou, Julia, Siegel, and several others. A recurrent theme of the authors' treatment is the center problem in complex dynamics. They present its complete history during this period and, in so doing, bring out analogies between complex dynamics and the study of differential equations, in particular, the problem of stability in Hamiltonian systems. Among these analogies are the use of iteration and problems involving small divisors which the authors examine in the work of Poincaré and others, linking them to complex dynamics, principally via the work of Samuel...
Estimating an Activity Driven Hidden Markov Model
Meyer, David A.; Shakeel, Asif
2015-01-01
We define a Hidden Markov Model (HMM) in which each hidden state has time-dependent $\\textit{activity levels}$ that drive transitions and emissions, and show how to estimate its parameters. Our construction is motivated by the problem of inferring human mobility on sub-daily time scales from, for example, mobile phone records.
Insight: Exploring Hidden Roles in Collaborative Play
Directory of Open Access Journals (Sweden)
Tricia Shi
2015-06-01
Full Text Available This paper looks into interaction modes between players in co-located, collaborative games. In particular, hidden traitor games, in which one or more players is secretly working against the group mission, has the effect of increasing paranoia and distrust between players, so this paper looks into the opposite of a hidden traitor – a hidden benefactor. Rather than sabotaging the group mission, the hidden benefactor would help the group achieve the end goal while still having a reason to stay hidden. The paper explores what games with such a role can look like and how the role changes player interactions. Finally, the paper addresses the divide between video game and board game interaction modes; hidden roles are not common within video games, but they are of growing prevalence in board games. This fact, combined with the exploration of hidden benefactors, reveals that hidden roles is a mechanic that video games should develop into in order to match board games’ complexity of player interaction modes.
Toonen, Willem H. J.; Graham, Angus; Pennington, Ben; Hunter, Morag; Strutt, Kris; Barker, Dominic; Masson, Aurelia; Emery, Virginia
2016-04-01
were contemporary. The abundance of ceramic material also allowed the reconstruction of sedimentation rates across the floodplain, which ranged between 0.8-2.2 mm/yr, largely in agreement with estimates from other studies. Importantly, there seems to have been a major decrease in sedimentation rates after the New Kingdom. Furthermore, the abandonment of the secondary channel of the Nile and the formation of a well-developed calcareous palaeosol (both of which could have been forced by drought and failing Nile floods) correlate with the demise of the New Kingdom. This suggests that regionally observed cultural and natural dynamics may have been driven by hydroclimatic variability in the larger Nile basin. A lower calcareous palaeosol, located at least 1m below the New Kingdom horizon, hints at a previous period of severe drought and its age is tentatively inferred as Old Kingdom. The age of this lower palaeosol needs to be confirmed by more precise dating, but could support the idea that cultural dynamics in ancient floodwater farming cultures are strongly linked to hydroclimatic change.
Helioscope bounds on hidden sector photons
Energy Technology Data Exchange (ETDEWEB)
Redondo, J.
2007-12-15
The flux of hypothetical ''hidden photons'' from the Sun is computed under the assumption that they interact with normal matter only through kinetic mixing with the ordinary standard model photon. Requiring that the exotic luminosity is smaller than the standard photon luminosity provides limits for the mixing parameter down to {chi}
Helioscope bounds on hidden sector photons
Energy Technology Data Exchange (ETDEWEB)
Redondo, J.
2007-12-15
The flux of hypothetical ''hidden photons'' from the Sun is computed under the assumption that they interact with normal matter only through kinetic mixing with the ordinary standard model photon. Requiring that the exotic luminosity is smaller than the standard photon luminosity provides limits for the mixing parameter down to {chi}
Institute of Scientific and Technical Information of China (English)
陈珂; 陈小英; 徐科
2007-01-01
如今Web上越来越多的信息可以通过查询接口获得,但为了获取某Hidden Web站点的页面,用户不得不键入一系列的关键词.由于没有直接指向Hidden Web页面的静态链接,当前大多搜索引擎不能发现和索引这些页面.然而,研究表明,由Hidden Web站点提供的高质量的信息对许多用户来说非常有价值.文章通过研究针对特定类型的表单,建立一个有效的Hidden Web爬虫,以便获取Hidden Web后台数据库信息.
Van Wychen, Wesley; Davis, Jamie; Burgess, David O.; Copland, Luke; Gray, Laurence; Sharp, Martin; Mortimer, Colleen
2016-01-01
Landsat 7 and RADARSAT-1/RADARSAT-2 satellite images are used to produce the most comprehensive record of glacier motion in the Canadian High Arctic to date and to characterize spatial and temporal variability in ice flow over the past ~15 years. This allows us to assess whether dynamically driven glacier change can be attributed to "surging" or "pulsing," or whether other mechanisms are involved. RADAR velocity mapping allows annual regional dynamic discharge (iceberg calving) to be calculated for 2000 and the period 2011-2015 (yielding a mean regional discharge of 2.21 ± 0.68 Gt a-1), and velocities derived from feature tracking of optical imagery allow for annual dynamic discharge to be calculated for select glaciers from 1999 to 2010. Since ~2011, several of the major tidewater-terminating glaciers within the region have decelerated and their dynamic discharge has decreased. Trinity and Wykeham Glaciers (Prince of Wales Icefield) represent a notable departure from this pattern as they have generally accelerated over the study period. The resulting increase in dynamic discharge from these glaciers entirely compensates (within error limits) for the decrease in discharge from the other tidewater glaciers across the study region. These two glaciers accounted for ~62% of total regional dynamic discharge in winter 2015 (compared to ~22% in 2000), demonstrating that total ice discharge from the Canadian High Arctic can be sensitive to variations in flow of just a few tidewater glaciers.
Gerber, Edwin P.; Manzini, Elisa
2016-01-01
Diagnostics of atmospheric momentum and energy transport are needed to investigate the origin of circulation biases in climate models and to understand the atmospheric response to natural and anthropogenic forcing. Model biases in atmospheric dynamics are one of the factors that increase uncertainty in projections of regional climate, precipitation and extreme events. Here we define requirements for diagnosing the atmospheric circulation and variability across temporal scales and for evaluati...
An Energy-Based State Observer for Dynamical Subsystems with Inaccessible State Variables
Khalil, I.S.M.; Sabanovic, Asif; Misra, Sarthak
2012-01-01
This work presents an energy-based state estimation formalism for a class of dynamical systems with inaccessible/unknown outputs, and systems at which sensor utilization is impractical, or when measurements can not be taken. The power-conserving physical interconnections among most of the dynamical
Srivastava, Nilabh; Haque, Imtiaz
2009-03-01
Over the past two decades, extensive research has been conducted on developing vehicle transmissions that meet the goals of reduced exhaust emissions and increased vehicle efficiency. A continuously variable transmission is an emerging automotive transmission technology that offers a continuum of gear ratios between desired limits. A chain CVT is a friction-limited drive whose dynamic performance and torque capacity rely significantly on the friction characteristic of the contact patch between the chain and the pulley. Although a CVT helps to maximize the vehicle fuel economy, its complete potential has not been accomplished in a mass-production vehicle. The present research focuses on developing models to analyze friction-induced nonlinear dynamics of a chain CVT drive and identify possible mechanisms that cause degradation of the overall dynamic performance by inducing chaos and self-sustained vibrations in the system. Two different mathematical models of friction, which characterize different operating or loading conditions, are embedded into a detailed planar multibody model of chain CVT in order to capture the various friction-induced effects in the system. Tools such as stick-slip oscillator dynamics, Lyapunov exponents, phase-space reconstruction, and recurrence plotting are incorporated to characterize the nonlinear dynamics of such a friction-limited system. The mathematical models, the computational scheme, and the results corresponding to different loading scenarios are discussed. The results discuss the influence of friction characteristics on the nonlinear dynamics and torque transmitting capacity of a chain CVT drive.
Institute of Scientific and Technical Information of China (English)
WONG Pak-kin; TAM Lap-mou; LI Ke
2007-01-01
In modern four-stroke engine technology, variable valve timing and lift control offers potential benefits for making a high-performance engine. A novel electro-hydraulic fully variable valve train for four-stroke automotive engines is introduced. The construction of the nonlinear mathematic model of the valve train system and its dynamic analysis are also presented. Experimental and simulation results show that the novel electro-hydraulic valve train can achieve fully variable valve timing and lift control. Consequently the engine performance on different loads and speeds will be significantly increased. The technology also permits the elimination of the traditional throttle valve in the gasoline engines and increases engine design flexibility.
Directory of Open Access Journals (Sweden)
Sindhu M R
2014-12-01
Full Text Available Variable speed drives are mostly preferred in industries, while considering energy saving, smooth control, flexible operation and fast response. On the other hand, this equipment generates dynamic harmonic distortions in source currents and draws variable reactive power demand depending on variation in load condition. These distortions propagate throughout the system and affect all the loads connected to the point of common coupling. Hence a dynamic harmonic and reactive compensator is necessary to enhance power quality to meet current and voltage distortion limits at point of common coupling as per IEEE standard. The most common choice for adjustable speed drives in industries is three phase voltage source inverter based induction motor drives which uses PWM technique for voltage, frequency and current control. This paper presents harmonic analysis of an induction motor drive in an industrial plant and development of adaptive dynamic harmonic and reactive compensator to improve power quality. A digital controller which is programmed with adaptive Artificial Neural Network (ANN based control algorithm is used for controlling shunt active filter. The simulation and experimental results show that the adaptive shunt active filter provides effective harmonic and reactive compensation in the system under steady state and dynamic load conditions.
Hidden scale in quantum mechanics
Giri, Pulak Ranjan
2007-01-01
We show that the intriguing localization of a free particle wave-packet is possible due to a hidden scale present in the system. Self-adjoint extensions (SAE) is responsible for introducing this scale in quantum mechanical models through the nontrivial boundary conditions. We discuss a couple of classically scale invariant free particle systems to illustrate the issue. In this context it has been shown that a free quantum particle moving on a full line may have localized wave-packet around the origin. As a generalization, it has also been shown that particles moving on a portion of a plane or on a portion of a three dimensional space can have unusual localized wave-packet.
UV variability and accretion dynamics in the young open cluster NGC 2264
Venuti, Laura; Irwin, Jonathan; Stauffer, John; Hillenbrand, Lynne; Rebull, Luisa; Cody, Ann Marie; Alencar, Silvia; Micela, Giuseppina; Flaccomio, Ettore; Peres, Giovanni
2015-01-01
We explore UV and optical variability signatures for several hundred members of NGC 2264 (3 Myr). We performed simultaneous u- and r-band monitoring over two full weeks with CFHT/MegaCam. About 750 young stars are probed; 40% of them are accreting. Statistically distinct variability properties are observed for accreting and non-accreting cluster members. The accretors exhibit a significantly higher level of variability than the non-accretors, especially in the UV. The amount of u-band variability correlates statistically with UV excess in disk-bearing objects, which suggests that accretion and star-disk interaction are the main sources of variability. Cool magnetic spots, several hundred degrees colder than the photosphere and covering from 5 to 30% of the stellar surface, appear to be the leading factor of variability for the non-accreting stars. In contrast, accretion spots, a few thousand degrees hotter than the photosphere and covering a few percent of the stellar surface, best reproduce the variability o...
Hidden attractors in a chaotic system with an exponential nonlinear term
Pham, V.-T.; Vaidyanathan, S.; Volos, C. K.; Jafari, S.
2015-07-01
Studying systems with hidden attractors is new attractive research direction because of its practical and threoretical importance. A novel system with an exponential nonlinear term, which can exhibit hidden attractors, is proposed in this work. Although new system possesses no equilibrium points, it displays rich dynamical behaviors, like chaos. By calculating Lyapunov exponents and bifurcation diagram, the dynamical behaviors of such system are discovered. Moreover, two important features of a chaotic system, the possibility of synchronization and the feasibility of the theoretical model, are also presented by introducing an adaptive synchronization scheme and designing a digital hardware platform-based emulator.
Stochastic precipitation generator with hidden state covariates
Kim, Yongku; Lee, GyuWon
2017-08-01
Time series of daily weather such as precipitation, minimum temperature and maximum temperature are commonly required for various fields. Stochastic weather generators constitute one of the techniques to produce synthetic daily weather. The recently introduced approach for stochastic weather generators is based on generalized linear modeling (GLM) with covariates to account for seasonality and teleconnections (e.g., with the El Niño). In general, stochastic weather generators tend to underestimate the observed interannual variance of seasonally aggregated variables. To reduce this overdispersion, we incorporated time series of seasonal dry/wet indicators in the GLM weather generator as covariates. These seasonal time series were local (or global) decodings obtained by a hidden Markov model of seasonal total precipitation and implemented in the weather generator. The proposed method is applied to time series of daily weather from Seoul, Korea and Pergamino, Argentina. This method provides a straightforward translation of the uncertainty of the seasonal forecast to the corresponding conditional daily weather statistics.
ADM-CLE approach for detecting slow variables in continuous time Markov chains and dynamic data
Cucuringu, Mihai
2015-01-01
A method for detecting intrinsic slow variables in high-dimensional stochastic chemical reaction networks is developed and analyzed. It combines anisotropic diffusion maps (ADM) with approximations based on the chemical Langevin equation (CLE). The resulting approach, called ADM-CLE, has the potential of being more efficient than the ADM method for a large class of chemical reaction systems, because it replaces the computationally most expensive step of ADM (running local short bursts of simulations) by using an approximation based on the CLE. The ADM-CLE approach can be used to estimate the stationary distribution of the detected slow variable, without any a-priori knowledge of it. If the conditional distribution of the fast variables can be obtained analytically, then the resulting ADM-CLE approach does not make any use of Monte Carlo simulations to estimate the distributions of both slow and fast variables.
Dynamical Mechanisms and Variability of Dry and Wet Spells in Iberia
Liberato, Margarida L. R.; Montero, Irene; Gouveia, Célia
2014-05-01
Dry and wet spells in Iberia have widespread ecological and environmental negative impacts resulting in major socioeconomic damages such as crop yield losses or increasing forest fire risk [Gouveia et al. 2009; Amraoui et al. 2013] and flash flooding, urban inundations, landslides and associated human and infrastructure damages [Liberato et al. 2013]. The 20th century was characterized by a negative trend on precipitation and a positive trend on temperature in southern Europe. On the other hand recent results suggest that there are opposite tendencies in the duration of wet and dry spells over the Iberia. At the monthly and seasonal scales, the North Atlantic Oscillation (NAO), the Eastern Atlantic (EA) and the Scandinavian (SCAN) patterns are important large-scale variability modes that control the Iberian precipitation regime. The NAO modulates the westerly atmospheric flow by shifting the polar jet and the associated storm-tracks. At the sub-monthly scale, extratropical cyclones have a significant impact on Iberian climate and are one of the primary causes of extreme events occurrence over the region [Liberato et al. 2011; 2013]. In this work we investigate the connection between midlatitude cyclones and the onset and recurrent character of droughts, heavy precipitation and spell duration in Iberia. Our results confirm the links between unusual circulation patterns with these extreme events. Moreover we show how the frequency on the occurrence of extratropical cyclones on the Euro-Atlantic region is critical in explaining the tails of the precipitation distribution in Iberia. Acknowledgments: This work was partially supported by national funds through FCT (Fundação para a Ciência e a Tecnologia, Portugal) under project QSECA (PTDC/AAG-GLO/4155/2012). References: Amraoui M., M. L. R. Liberato, T. J. Calado, C. C. DaCamara, L. P. Coelho, R. M. Trigo, C. M. Gouveia (2013) Fire activity over Mediterranean Europe based on information from Meteosat-8. Forest
Family system dynamics and type 1 diabetic glycemic variability: a vector-auto-regressive model.
Günther, Moritz Philipp; Winker, Peter; Böttcher, Claudia; Brosig, Burkhard
2013-06-01
Statistical approaches rooted in econometric methodology, so far foreign to the psychiatric and psychological realms have provided exciting and substantial new insights into complex mind-body interactions over time and individuals. Over 120 days, this structured diary study explored the mutual interactions of emotions within a classic 3-person family system with its Type 1 diabetic adolescent's daily blood glucose variability. Glycemic variability was measured through daily standard deviations of blood glucose determinations (at least 3 per day). Emotions were captured individually utilizing the self-assessment manikin on affective valence (negative-positive), activation (calm-excited), and control (dominated-dominant). Auto- and cross-correlating the stationary absolute (level) values of the mutually interacting parallel time series data sets through vector autoregression (VAR, grounded in econometric theory) allowed for the formulation of 2 concordant models. Applying Cholesky Impulse Response Analysis at a 95% confidence interval, we provided evidence for an adolescent being happy, calm, and in control to exhibit less glycemic variability and hence diabetic derailment. A nondominating mother and a happy father seemed to also reduce glycemic variability. Random shocks increasing glycemic variability affected only the adolescent and her father: In 1 model, the male parent felt in charge; in the other, he calmed down while his daughter turned sad. All reactions to external shocks lasted for less than 4 full days. Extant literature on affect and glycemic variability in Type 1 diabetic adolescents as well as challenges arising from introducing econometric theory to the field were discussed.
Spiral orbits and oscillations in historical dynamics
Cheon, Taksu
2015-01-01
We introduce the concept of metaasabiya, the second non-material resource, to the asabiya theory of historical dynamics. We find that the resulting three variable dynamical system has peculiar features such as repelling or attracting axes and spiralling orbits in the phase space. Depending on the initial state, the system can go through series of oscillatory rises and falls, mimicking the geopolitical evolution of real-world polities. These distinctive features, absent in conventional Lotka-Volterra type biological systems, reveal the hidden richness inherent in the asabiya theory.
Variability of dynamic source parameters inferred from kinematic models of past earthquakes
Causse, M.
2013-12-24
We analyse the scaling and distribution of average dynamic source properties (fracture energy, static, dynamic and apparent stress drops) using 31 kinematic inversion models from 21 crustal earthquakes. Shear-stress histories are computed by solving the elastodynamic equations while imposing the slip velocity of a kinematic source model as a boundary condition on the fault plane. This is achieved using a 3-D finite difference method in which the rupture kinematics are modelled with the staggered-grid-split-node fault representation method of Dalguer & Day. Dynamic parameters are then estimated from the calculated stress-slip curves and averaged over the fault plane. Our results indicate that fracture energy, static, dynamic and apparent stress drops tend to increase with magnitude. The epistemic uncertainty due to uncertainties in kinematic inversions remains small (ϕ ∼ 0.1 in log10 units), showing that kinematic source models provide robust information to analyse the distribution of average dynamic source parameters. The proposed scaling relations may be useful to constrain friction law parameters in spontaneous dynamic rupture calculations for earthquake source studies, and physics-based near-source ground-motion prediction for seismic hazard and risk mitigation.
Hidden Markov models: the best models for forager movements?
Directory of Open Access Journals (Sweden)
Rocio Joo
Full Text Available One major challenge in the emerging field of movement ecology is the inference of behavioural modes from movement patterns. This has been mainly addressed through Hidden Markov models (HMMs. We propose here to evaluate two sets of alternative and state-of-the-art modelling approaches. First, we consider hidden semi-Markov models (HSMMs. They may better represent the behavioural dynamics of foragers since they explicitly model the duration of the behavioural modes. Second, we consider discriminative models which state the inference of behavioural modes as a classification issue, and may take better advantage of multivariate and non linear combinations of movement pattern descriptors. For this work, we use a dataset of >200 trips from human foragers, Peruvian fishermen targeting anchovy. Their movements were recorded through a Vessel Monitoring System (∼1 record per hour, while their behavioural modes (fishing, searching and cruising were reported by on-board observers. We compare the efficiency of hidden Markov, hidden semi-Markov, and three discriminative models (random forests, artificial neural networks and support vector machines for inferring the fishermen behavioural modes, using a cross-validation procedure. HSMMs show the highest accuracy (80%, significantly outperforming HMMs and discriminative models. Simulations show that data with higher temporal resolution, HSMMs reach nearly 100% of accuracy. Our results demonstrate to what extent the sequential nature of movement is critical for accurately inferring behavioural modes from a trajectory and we strongly recommend the use of HSMMs for such purpose. In addition, this work opens perspectives on the use of hybrid HSMM-discriminative models, where a discriminative setting for the observation process of HSMMs could greatly improve inference performance.
Hidden torsion, 3-manifolds, and homology cobordism
Cha, Jae Choon
2011-01-01
This paper continues our exploration of homology cobordism of 3-manifolds using our recent results on Cheeger-Gromov rho-invariants associated to amenable representations. We introduce a new type of torsion in 3-manifold groups we call hidden torsion, and an algebraic approximation we call local hidden torsion. We construct infinitely many hyperbolic 3-manifolds which have local hidden torsion in the transfinite lower central subgroup. By realizing Cheeger-Gromov invariants over amenable groups, we show that our hyperbolic 3-manifolds are not pairwise homology cobordant, yet remain indistinguishable by any prior known homology cobordism invariants.
Visible Effects of Invisible Hidden Valley Radiation
Carloni, Lisa
2010-01-01
Assuming there is a new gauge group in a Hidden Valley, and a new type of radiation, can we observe it through its effect on the kinematic distributions of recoiling visible particles? Specifically, what are the collider signatures of radiation in a hidden sector? We address these questions using a generic SU(N)-like Hidden Valley model that we implement in Pythia. We find that in both the e+e- and the LHC cases the kinematic distributions of the visible particles can be significantly affected by the valley radiation. Without a proper understanding of such effects, inferred masses of "communicators" and of invisible particles can be substantially off.
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Sabine eDemotes-Mainard
2013-10-01
Full Text Available Bush rose architecture, among other factors, such as plant health, determines plant visual quality. The commercial product is the individual plant and interplant variability may be high within a crop. Thus, both mean plant architecture and interplant variability should be studied. Expansion is an important feature of architecture, but it has been little studied at the level of individual organs in bush roses. We investigated the expansion kinetics of primary shoot organs, to develop a model reproducing the organ expansion of real crops from non destructive input variables. We took interplant variability in expansion kinetics and the model’s ability to simulate this variability into account. Changes in leaflet and internode dimensions over thermal time were recorded for primary shoot expansion, on 83 plants from three crops grown in different climatic conditions and densities. An empirical model was developed, to reproduce organ expansion kinetics for individual plants of a real crop of bush rose primary shoots. Leaflet or internode length was simulated as a logistic function of thermal time. The model was evaluated by cross-validation. We found that differences in leaflet or internode expansion kinetics between phytomer positions and between plants at a given phytomer position were due mostly to large differences in time of organ expansion and expansion rate, rather than differences in expansion duration. Thus, in the model, the parameters linked to expansion duration were predicted by values common to all plants, whereas variability in final size and organ expansion time was captured by input data. The model accurately simulated leaflet and internode expansion for individual plants (RMSEP = 7.3% and 10.2% of final length, respectively. Thus, this study defines the measurements required to simulate expansion and provides the first model simulating organ expansion in rosebush to capture interplant variability.
Korean Conference on Several Complex Variables
Byun, Jisoo; Gaussier, Hervé; Hirachi, Kengo; Kim, Kang-Tae; Shcherbina, Nikolay
2015-01-01
This volume includes 28 chapters by authors who are leading researchers of the world describing many of the up-to-date aspects in the field of several complex variables (SCV). These contributions are based upon their presentations at the 10th Korean Conference on Several Complex Variables (KSCV10), held as a satellite conference to the International Congress of Mathematicians (ICM) 2014 in Seoul, Korea. SCV has been the term for multidimensional complex analysis, one of the central research areas in mathematics. Studies over time have revealed a variety of rich, intriguing, new knowledge in complex analysis and geometry of analytic spaces and holomorphic functions which were "hidden" in the case of complex dimension one. These new theories have significant intersections with algebraic geometry, differential geometry, partial differential equations, dynamics, functional analysis and operator theory, and sheaves and cohomology, as well as the traditional analysis of holomorphic functions in all dimensions. This...
Yuan, Dongliang; Xu, Peng; Xu, Tengfei
2017-01-01
An experiment using the Community Climate System Model (CCSM4), a participant of the Coupled Model Intercomparison Project phase-5 (CMIP5), is analyzed to assess the skills of this model in simulating and predicting the climate variabilities associated with the oceanic channel dynamics across the Indo-Pacific Oceans. The results of these analyses suggest that the model is able to reproduce the observed lag correlation between the oceanic anomalies in the southeastern tropical Indian Ocean and those in the cold tongue in the eastern equatorial Pacific Ocean at a time lag of 1 year. This success may be largely attributed to the successful simulation of the interannual variations of the Indonesian Throughflow, which carries the anomalies of the Indian Ocean Dipole (IOD) into the western equatorial Pacific Ocean to produce subsurface temperature anomalies, which in turn propagate to the eastern equatorial Pacific to generate ENSO. This connection is termed the "oceanic channel dynamics" and is shown to be consistent with the observational analyses. However, the model simulates a weaker connection between the IOD and the interannual variability of the Indonesian Throughflow transport than found in the observations. In addition, the model overestimates the westerly wind anomalies in the western-central equatorial Pacific in the year following the IOD, which forces unrealistic upwelling Rossby waves in the western equatorial Pacific and downwelling Kelvin waves in the east. This assessment suggests that the CCSM4 coupled climate system has underestimated the oceanic channel dynamics and overestimated the atmospheric bridge processes.
Directory of Open Access Journals (Sweden)
Ajibola Arewa
2013-12-01
Full Text Available The paper investigates the long-run relationship between government expenditures and a set of macroeconomic variables (GDP, consumer price index and unemployment using annual data collected from CBN statistical bulletin for a period of 19891 to 2011. It particularly adopts Johansen multivariate co integration for its estimation procedure and discovers that there is long-run relationship between government expenditure and the specified macroeconomic variables. It also discovers that an increase in capital expenditure improves economic bliss, while recurrent expenditure is detrimental to growth. Finally, our findings show that most of the variables do not Granger cause each other, but however, recurrent expenditure Granger causes prices, in the same veil capital expenditure does granger cause unemployment.
STATIC AND DYNAMIC LOCATION OF VARIABLE IMPEDANCE DEVICES FOR STABILITY STUDIES
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N. Magaji
2013-01-01
Full Text Available This study used the concept of model controllability and observability in product form called residue factor to find the best location of Thyristor-Controlled based series and shunt devices called variable impedance devices. The success of this controller depends on its best possible location in busbar or line of power system network. The method is based on the relationship between the parameters of variable impedance devices to the vital modes. Linearization of non linear model of Power system and the thyristors based FACTS devices provide mens of computing residue factor and singular value factor. The location of variable impedance or thyristors based controllers have been calculated for the base case only. The usefulness of the these methods of placement considered 16 machines, 68 bus systems.
Langevin dynamics for vector variables driven by multiplicative white noise: A functional formalism.
Moreno, Miguel Vera; Arenas, Zochil González; Barci, Daniel G
2015-04-01
We discuss general multidimensional stochastic processes driven by a system of Langevin equations with multiplicative white noise. In particular, we address the problem of how time reversal diffusion processes are affected by the variety of conventions available to deal with stochastic integrals. We present a functional formalism to build up the generating functional of correlation functions without any type of discretization of the Langevin equations at any intermediate step. The generating functional is characterized by a functional integration over two sets of commuting variables, as well as Grassmann variables. In this representation, time reversal transformation became a linear transformation in the extended variables, simplifying in this way the complexity introduced by the mixture of prescriptions and the associated calculus rules. The stochastic calculus is codified in our formalism in the structure of the Grassmann algebra. We study some examples such as higher order derivative Langevin equations and the functional representation of the micromagnetic stochastic Landau-Lifshitz-Gilbert equation.
Hidden beauty baryon states in the local hidden gauge approach with heavy quark spin symmetry
Energy Technology Data Exchange (ETDEWEB)
Xiao, C.W.; Oset, E. [Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigacion de Paterna, Departamento de Fisica Teorica and IFIC, Valencia (Spain)
2013-11-15
Using a coupled-channel unitary approach, combining the heavy quark spin symmetry and the dynamics of the local hidden gauge, we investigate the meson-baryon interaction with hidden beauty and obtain several new states of N around 11 GeV. We consider the basis of states {eta}{sub b} N, {Upsilon};N, B {Lambda}{sub b}, B {Sigma}{sub b}, B{sup *}{Lambda}{sub b}, B{sup *}{Sigma}{sub b}, B{sup *}{Sigma}{sub b}{sup *} and find four basic bound states which correspond to B {Sigma}{sub b}, B {Sigma}{sub b}{sup *}, B{sup *}{Sigma}{sub b} and B{sup *}{Sigma}{sub b}{sup *}, decaying mostly into {eta}{sub b} N and {Upsilon}N and with a binding energy about 50-130 MeV with respect to the thresholds of the corresponding channel. All of them have isospin I = 1/2, and we find no bound states or resonances in I = 3/2. The B {Sigma}{sub b} state appears in J = 1/2, the B {Sigma}{sub b}{sup *} in J = 3/2, the B{sup *}{Sigma}{sub b} appears nearly degenerate in J = 1/2, 3/2 and the B{sup *}{Sigma}{sub b}{sup *} appears nearly degenerate in J = 1/2, 3/2, 5/2. These states have a width from 2-110 MeV, with conservative estimates of uncertainties, except for the one in J = 5/2 which has zero width since it cannot decay into any of the states of the basis chosen. We make generous estimates of the uncertainties and find that within very large margins these states appear bound. (orig.)
Inference in Hidden Markov Models with Explicit State Duration Distributions
Dewar, Michael; Wood, Frank
2012-01-01
In this letter we borrow from the inference techniques developed for unbounded state-cardinality (nonparametric) variants of the HMM and use them to develop a tuning-parameter free, black-box inference procedure for Explicit-state-duration hidden Markov models (EDHMM). EDHMMs are HMMs that have latent states consisting of both discrete state-indicator and discrete state-duration random variables. In contrast to the implicit geometric state duration distribution possessed by the standard HMM, EDHMMs allow the direct parameterisation and estimation of per-state duration distributions. As most duration distributions are defined over the positive integers, truncation or other approximations are usually required to perform EDHMM inference.
ADM-CLE Approach for Detecting Slow Variables in Continuous Time Markov Chains and Dynamic Data
2015-04-01
Max Plank ...v a ri a b le s (d) 0 50 100 150 200 0 0.2 0.4 0.6 0.8 1 Our recovered slow variables (1:201) J a c c a rd S im ila ri ty I n d e x Max matching in...250 300 0 0.2 0.4 0.6 0.8 1 Our recovered slow variables (1:314) J a c c a rd S im ila ri ty I n d e x Max matching in the Jaccard index matrix
Contribution of variable-speed pump hydro storage for power system dynamic performance
Silva, B.; Moreira, C.
2017-04-01
This paper presents the study of variable-speed Pump Storage Powerplant (PSP) in the Portuguese power system. It evaluates the progressive integration in three major locations and compares the power system performance following a severe fault event with consequent disconnection of non-Fault Ride-through (FRT) compliant Wind Farms (WF). To achieve such objective, a frequency responsive model was developed in PSS/E and was further used to substitute existing fixed-speed PSP. The results allow identifying a clear enhancement on the power system performance by the presence of frequency responsive variable-speed PSP, especially for the scenario presented, with high level of renewables integration.
Hidden systematics of fission channels
Directory of Open Access Journals (Sweden)
Schmidt Karl-Heinz
2013-12-01
of the fissioning system obey a hidden systematics that can be explained by the number of states in the vicinity of the outer fission barrier as a function of mass asymmetry, if the potential is constructed as the sum of the macroscopic contribution of the compound nucleus and empirically determined fragment shells. This hidden systematics also explains the transition from asymmetric to symmetric fission around 226Th and around 258Fm.
Exploring the dynamics of balance data - movement variability in terms of drift and diffusion
Energy Technology Data Exchange (ETDEWEB)
Gottschall, Julia [Institute of Physics, University of Oldenburg, D-26111 Oldenburg (Germany)], E-mail: julia.gottschall@uni-oldenburg.de; Peinke, Joachim [Institute of Physics, University of Oldenburg, D-26111 Oldenburg (Germany)], E-mail: peinke@uni-oldenburg.de; Lippens, Volker [Department of Human Movement, University of Hamburg, Moller Street 10, D-20148 Hamburg (Germany)], E-mail: vlippens@uni-hamburg.de; Nagel, Volker [Department of Human Movement, University of Hamburg, Moller Street 10, D-20148 Hamburg (Germany)
2009-02-23
We introduce a method to analyze postural control on a balance board by reconstructing the underlying dynamics in terms of a Langevin model. Drift and diffusion coefficients are directly estimated from the data and fitted by a suitable parametrization. The governing parameters are utilized to evaluate balance performance and the impact of supra-postural tasks on it. We show that the proposed method of analysis gives not only self-consistent results but also provides a plausible model for the reconstruction of balance dynamics.
Exploring the dynamics of balance data — movement variability in terms of drift and diffusion
Gottschall, Julia; Peinke, Joachim; Lippens, Volker; Nagel, Volker
2009-02-01
We introduce a method to analyze postural control on a balance board by reconstructing the underlying dynamics in terms of a Langevin model. Drift and diffusion coefficients are directly estimated from the data and fitted by a suitable parametrization. The governing parameters are utilized to evaluate balance performance and the impact of supra-postural tasks on it. We show that the proposed method of analysis gives not only self-consistent results but also provides a plausible model for the reconstruction of balance dynamics.
Arzeliès, Henri
1972-01-01
Relativistic Point Dynamics focuses on the principles of relativistic dynamics. The book first discusses fundamental equations. The impulse postulate and its consequences and the kinetic energy theorem are then explained. The text also touches on the transformation of main quantities and relativistic decomposition of force, and then discusses fields of force derivable from scalar potentials; fields of force derivable from a scalar potential and a vector potential; and equations of motion. Other concerns include equations for fields; transfer of the equations obtained by variational methods int
UV Photography Shows Hidden Sun Damage
... mcat1=de12", ]; for (var c = 0; c UV photography shows hidden sun damage A UV photograph gives ... developing skin cancer and prematurely aged skin. Normal photography UV photography 18 months of age: This boy's ...
Faddeev-Jackiw approach to hidden symmetries
Wotzasek, C
1994-01-01
The study of hidden symmetries within Dirac's formalism does not possess a systematic procedure due to the lack of first-class constraints to act as symmetry generators. On the other hand, in the Faddeev-Jackiw approach, gauge and reparametrization symmetries are generated by the null eigenvectors of the sympletic matrix and not by constraints, suggesting the possibility of dealing systematically with hidden symmetries through this formalism. It is shown in this paper that indeed hidden symmetries of noninvariant or gauge fixed systems are equally well described by null eigenvectors of the sympletic matrix, just as the explicit invariances. The Faddeev-Jackiw approach therefore provide a systematic algorithm for treating all sorts of symmetries in an unified way. This technique is illustrated here by the SL(2,R) Kac-Moody current algebra of the 2-D induced gravity proposed by Polyakov, which is a hidden symmetry in the canonical approach of constrained systems via Dirac's method, after conformal and reparamet...
Fibroid Tumors in Women: A Hidden Epidemic?
... Issue Past Issues Fibroid Tumors in Women: A Hidden Epidemic? Past Issues / Spring 2007 Table of Contents ... fibroids@rics.bwh.harvard.edu , or visit our Web site: www.fibroids.net . You may also write ...
Hidden Regular Variation: Detection and Estimation
Mitra, Abhimanyu
2010-01-01
Hidden regular variation defines a subfamily of distributions satisfying multivariate regular variation on $\\mathbb{E} = [0, \\infty]^d \\backslash \\{(0,0, ..., 0) \\} $ and models another regular variation on the sub-cone $\\mathbb{E}^{(2)} = \\mathbb{E} \\backslash \\cup_{i=1}^d \\mathbb{L}_i$, where $\\mathbb{L}_i$ is the $i$-th axis. We extend the concept of hidden regular variation to sub-cones of $\\mathbb{E}^{(2)}$ as well. We suggest a procedure of detecting the presence of hidden regular variation, and if it exists, propose a method of estimating the limit measure exploiting its semi-parametric structure. We exhibit examples where hidden regular variation yields better estimates of probabilities of risk sets.
Kabaca, Tolga
2013-01-01
Solution set of any inequality or compound inequality, which has one-variable, lies in the real line which is one dimensional. So a difficulty appears when computer assisted graphical representation is intended to use for teaching these topics. Sketching a one-dimensional graph by using computer software is not a straightforward work. In this…
Online dynamic flight optimisation applied to guidance of a variable-flow ducted rocket
Halswijk, W.H.C.
2009-01-01
The Variable-Flow Ducted Rocket (VFDR) is a type of ramjet that can control the fuel mass flow to the combustion chamber. It combines the high efficiency at high-speed of ramjets with the throttlability of turbofans, and this makes VFDR propulsion an excellent choice for high speed, long range missi
Dynamic traffic management on a familiar road : Failing to detect changes in variable speed limits
Harms, Ilse M.; Brookhuis, Karel A.
2016-01-01
Variable speed limits (VSL) are used more commonly around the globe lately. Although on a macroscopic level positive effects of VSLs have been reported, the caveat is that the impact of VSLs is very sensitive to the level of driver compliance. Thus far it is unknown whether all individual drivers ar
Gruber, Andreas; Baumgartner, Daniel; Zimmermann, Jolanda; Oberhuber, Walter
2009-06-01
We determined the temporal dynamic of cambial activity and xylem development of stone pine (Pinus cembra L.) throughout the treeline ecotone. Repeated micro-sampling of the developing tree ring was carried out during the growing seasons 2006 and 2007 at the timberline (1950 m a.s.l.), treeline (2110 m a.s.l.) and within the krummholz belt (2180 m a.s.l.) and the influence of climate variables on intra-annual wood formation was determined.At the beginning of both growing seasons, highest numbers of cambial and enlarging cells were observed at the treeline. Soil temperatures at time of initiation of cambial activity were c. 1.5 °C higher at treeline (open canopy) compared to timberline (closed canopy), suggesting that a threshold root-zone temperature is involved in triggering onset of above ground stem growth.The rate of xylem cell production determined in two weekly intervals during June through August 2006-2007 was significantly correlated with air temperature (temperature sums expressed as degree-days and mean daily maximum temperature) at the timberline only. Lack of significant relationships between tracheid production and temperature variables at the treeline and within the krummholz belt support past dendroclimatological studies that more extreme environmental conditions (e.g., wind exposure, frost desiccation, late frost) increasingly control tree growth above timberline.Results of this study revealed that spatial and temporal (i.e. year-to-year) variability in timing and dynamic of wood formation of Pinus cembra is strongly influenced by local site factors within the treeline ecotone and the dynamics of seasonal temperature variation, respectively.
Climatic variables and malaria transmission dynamics in Jimma town, South West Ethiopia
Directory of Open Access Journals (Sweden)
Abebe Gemeda
2011-03-01
Full Text Available Abstract Background:- In Ethiopia, malaria is seasonal and unstable, causing frequent epidemics. It usually occurs at altitudes 2,000 m above sea level. For transmission of malaria parasite, climatic factors are important determinants as well as non-climatic factors that can negate climatic influences. Indeed, there is a scarcity of information on the correlation between climatic variability and malaria transmission risk in Ethiopia in general and in the study area in particular. Therefore, the aim of this study was to determine the level of correlation between meteorological variables and malaria cases. Methods: - Time-series analysis was conducted using data on monthly meteorological variables and monthly total malaria in Jimma town, south west Ethiopia, for the period 2000-2009. All the data were entered and analyzed using SPSS-15 database program. Spearman correlation and linear regression analysis were used to asses association between the variables. Results: - During last ten years (2000-2009, a fluctuating trend of malaria transmission was observed with P.vivax becoming predominant species. Spearman correlation analysis showed that monthly minimum temperature, total rainfall and two measures of relative humidity were positively related with malaria but monthly maximum temperature negatively related. Also regression analysis suggested that monthly minimum (p = 0.008, monthly maximum temperature (p = 0.013 and monthly total rainfall (p = 0.040, at one month lagged effect, were significant meteorological factors for transmission of malaria in the study area. Conclusion: - Malaria incidences in the last decade seem to have a significant association with meteorological variables. In future, prospective and multidisciplinary cooperative research involving researchers from the fields of parasitology, epidemiology, botany, agriculture and climatology is necessary to identify the real effect of meteorological factors on vector- borne diseases like
K.T.D. Thai; B. Cazelles; N.V. Nguyen; L.T. Vo; M.F. Boni; J. Farrar; C.P. Simmons; H.R. van Doorn; P.J. de Vries
2010-01-01
Background: Dengue is a major global public health problem with increasing incidence and geographic spread. The epidemiology is complex with long inter-epidemic intervals and endemic with seasonal fluctuations. This study was initiated to investigate dengue transmission dynamics in Binh Thuan provin
Joint dynamics and intra-subject variability during countermovement jumps in children and adults
DEFF Research Database (Denmark)
Raffalt, Peter C; Alkjær, Tine; Simonsen, Erik B
2016-01-01
work, hip joint moment and hip and knee joint power. Higher intra-subject variation was observed in horizontal joint reaction force components for the children and higher intra-subject variation in the segment angular inertia components was observed for the adults. The joint dynamics of children during...
Anacleto, Osvaldo; Queen, Catriona; Albers, Casper J.
2013-01-01
Traffic flow data are routinely collected for many networks worldwide. These invariably large data sets can be used as part of a traffic management system, for which good traffic flow forecasting models are crucial. The linear multiregression dynamic model (LMDM) has been shown to be promising for f
Institute of Scientific and Technical Information of China (English)
ZHENG Fei; WANG Hui; WAN Liying
2015-01-01
In this paper, interannual variations of the ocean dynamic height over the tropical Pacific are diagnosed using three-dimensional temperature and salinity fields from Argo profiles, with a focus on the effects of interannually varying salinity on the El Ni(n)o-Southern Oscillation (ENSO) evolutions. The diagnostic analyses clearly demonstrate a significant and large role that the salinity field plays in modulating the sea surface dynamic height (SSDH) in the western tropical Pacific. In particular, the contribution of the interannually varying salinity to the interannual variations in SSDH approximately equals to that of the interannually varying temperature. Over the western equatorial Pacific, the salinity variability was responsible for a 30% to 40% reduction in SSDH anomaly in opposition to the thermal build up in SSDH anomaly, providing an important contribution to modulating the seasonal-to-interannual evolution of the tropical Pacific Ocean and affecting the developing of ENSO events.
Vincenzi, Simone
2014-08-06
One of the most dramatic consequences of climate change will be the intensification and increased frequency of extreme events. I used numerical simulations to understand and predict the consequences of directional trend (i.e. mean state) and increased variability of a climate variable (e.g. temperature), increased probability of occurrence of point extreme events (e.g. floods), selection pressure and effect size of mutations on a quantitative trait determining individual fitness, as well as the their effects on the population and genetic dynamics of a population of moderate size. The interaction among climate trend, variability and probability of point extremes had a minor effect on risk of extinction, time to extinction and distribution of the trait after accounting for their independent effects. The survival chances of a population strongly and linearly decreased with increasing strength of selection, as well as with increasing climate trend and variability. Mutation amplitude had no effects on extinction risk, time to extinction or genetic adaptation to the new climate. Climate trend and strength of selection largely determined the shift of the mean phenotype in the population. The extinction or persistence of the populations in an 'extinction window' of 10 years was well predicted by a simple model including mean population size and mean genetic variance over a 10-year time frame preceding the 'extinction window', although genetic variance had a smaller role than population size in predicting contemporary risk of extinction.
Stachnik, J. P.; Waliser, D. E.; Majda, A.; Stechmann, S.
2013-12-01
The Madden-Julian Oscillation (MJO) is the leading mode of intraseasonal variability in the tropics. Despite its importance toward determining large-scale variability at both low-latitudes and the extratropics, MJO prediction often suffers from low skill regarding event initiation and its overall simulation remains a challenge in many global climate models (GCMs). The MJO 'skeleton' model, originally developed by Majda and Stechmann (2009), is a new low-order dynamic model that is capable of reproducing several salient features of the MJO despite its many simplifications relative to higher-order GCMs. Among their successes, the newest version of the skeleton model is able to reproduce the intermittent generation of MJO events, including organization into MJO wave trains that experience both growth and decay. This study presents an analysis of initiation events in the skeleton model. Higher-order features, such as the organization into wave trains, are examined herein and we document the simulated heating and moisture variability in the model compared to satellite-derived observations and reanalyses. We likewise present a composite analysis of the thermodynamic fields related to the initiation of primary and successive MJO events, as well as those precursor conditions leading to quiescent periods of the MJO. Time permitting, we also evaluate the multi-scale structures and other aspects of heating and moisture variability in the model (e.g., asymmetry between active and inactive periods) compared to distributions of integrated heating and moisture in Tropical Rainfall Measuring Mission (TRMM) observations and other datasets.
Hidden figures are ever present.
Mens, L H; Leeuwenberg, E L
1988-11-01
Preference judgments about alternative interpretations of unambiguous patterns can be explained in terms of a rivalry between a preferred and a second-best interpretation (cf. Leeuwenberg & Buffart, 1983). We tested whether this second-best interpretation corresponds to a suppressed but concurrently present interpretation or whether it merely reflects an alternative view that happens to be preferred less often. Two patterns were present immediately following each other with a very short onset asynchrony: a complete pattern and one out of three possible subpatterns of it, corresponding to the best, the second best, or an odd interpretation of the complete pattern. Subjects indicated which subpattern was presented by choosing among the three subpatterns shown after each trial. The scores, corrected for response-bias effects, indicated a relative facilitation of the second-best interpretation, in agreement with its predicted "hidden" presence. This result is more in line with theories that capitalize on the quality of the finally selected representation than with processing models aimed at reaching one single solution as fast and as economically as possible.
Constraining solar hidden photons using HPGe detector
Energy Technology Data Exchange (ETDEWEB)
Horvat, R.; Kekez, D., E-mail: Dalibor.Kekez@irb.hr; Krčmar, M.; Krečak, Z.; Ljubičić, A.
2013-04-25
In this Letter we report on the results of our search for photons from a U(1) gauge factor in the hidden sector of the full theory. With our experimental setup we observe the single spectrum in a HPGe detector arising as a result of the photoelectric-like absorption of hidden photons emitted from the Sun on germanium atoms inside the detector. The main ingredient of the theory used in our analysis, a severely constrained kinetic mixing from the two U(1) gauge factors and massive hidden photons, entails both photon into hidden state oscillations and a minuscule coupling of hidden photons to visible matter, of which the latter our experimental setup has been designed to observe. On a theoretical side, full account was taken of the effects of refraction and damping of photons while propagating in Sun's interior as well as in the detector. We exclude hidden photons with kinetic couplings χ>(2.2×10{sup −13}–3×10{sup −7}) in the mass region 0.2 eV≲m{sub γ{sup ′}}≲30 keV. Our constraints on the mixing parameter χ in the mass region from 20 eV up to 15 keV prove even slightly better then those obtained recently by using data from the CAST experiment, albeit still somewhat weaker than those obtained from solar and HB stars lifetime arguments.
Schmidt, Burkhard; Lorenz, Ulf
2017-04-01
WavePacket is an open-source program package for the numerical simulation of quantum-mechanical dynamics. It can be used to solve time-independent or time-dependent linear Schrödinger and Liouville-von Neumann-equations in one or more dimensions. Also coupled equations can be treated, which allows to simulate molecular quantum dynamics beyond the Born-Oppenheimer approximation. Optionally accounting for the interaction with external electric fields within the semiclassical dipole approximation, WavePacket can be used to simulate experiments involving tailored light pulses in photo-induced physics or chemistry. The graphical capabilities allow visualization of quantum dynamics 'on the fly', including Wigner phase space representations. Being easy to use and highly versatile, WavePacket is well suited for the teaching of quantum mechanics as well as for research projects in atomic, molecular and optical physics or in physical or theoretical chemistry. The present Part I deals with the description of closed quantum systems in terms of Schrödinger equations. The emphasis is on discrete variable representations for spatial discretization as well as various techniques for temporal discretization. The upcoming Part II will focus on open quantum systems and dimension reduction; it also describes the codes for optimal control of quantum dynamics. The present work introduces the MATLAB version of WavePacket 5.2.1 which is hosted at the Sourceforge platform, where extensive Wiki-documentation as well as worked-out demonstration examples can be found.
Douw, Linda; Wakeman, Daniel G; Tanaka, Naoaki; Liu, Hesheng; Stufflebeam, Steven M
2016-12-17
The brain is a dynamic, flexible network that continuously reconfigures. However, the neural underpinnings of how state-dependent variability of dynamic functional connectivity (vdFC) relates to cognitive flexibility are unclear. We therefore investigated flexible functional connectivity during resting-state and task-state functional magnetic resonance imaging (rs-fMRI and t-fMRI, resp.) and performed separate, out-of-scanner neuropsychological testing. We hypothesize that state-dependent vdFC between the frontoparietal network (FPN) and the default mode network (DMN) relates to cognitive flexibility. Seventeen healthy subjects performed the Stroop color word test and underwent t-fMRI (Stroop computerized version) and rs-fMRI. Time series were extracted from a cortical atlas, and a sliding window approach was used to obtain a number of correlation matrices per subject. vdFC was defined as the standard deviation of connectivity strengths over these windows. Higher task-state FPN-DMN vdFC was associated with greater out-of-scanner cognitive flexibility, while the opposite relationship was present for resting-state FPN-DMN vdFC. Moreover, greater contrast between task-state and resting-state vdFC related to better cognitive performance. In conclusion, our results suggest that not only the dynamics of connectivity between these networks is seminal for optimal functioning, but also that the contrast between dynamics across states reflects cognitive performance.
Directory of Open Access Journals (Sweden)
William A Griffin
Full Text Available Sequential affect dynamics generated during the interaction of intimate dyads, such as married couples, are associated with a cascade of effects-some good and some bad-on each partner, close family members, and other social contacts. Although the effects are well documented, the probabilistic structures associated with micro-social processes connected to the varied outcomes remain enigmatic. Using extant data we developed a method of classifying and subsequently generating couple dynamics using a Hierarchical Dirichlet Process Hidden semi-Markov Model (HDP-HSMM. Our findings indicate that several key aspects of existing models of marital interaction are inadequate: affect state emissions and their durations, along with the expected variability differences between distressed and nondistressed couples are present but highly nuanced; and most surprisingly, heterogeneity among highly satisfied couples necessitate that they be divided into subgroups. We review how this unsupervised learning technique generates plausible dyadic sequences that are sensitive to relationship quality and provide a natural mechanism for computational models of behavioral and affective micro-social processes.
Resing, Wilma C M; Bakker, Merel; Pronk, Christine M E; Elliott, Julian G
2017-01-01
The current study investigated developmental trajectories of analogical reasoning performance of 104 7- and 8-year-old children. We employed a microgenetic research method and multilevel analysis to examine the influence of several background variables and experimental treatment on the children's developmental trajectories. Our participants were divided into two treatment groups: repeated practice alone and repeated practice with training. Each child received an initial working memory assessment and was subsequently asked to solve figural analogies on each of several sessions. We examined children's analogical problem-solving behavior and their subsequent verbal accounts of their employed solving processes. We also investigated the influence of verbal and visual-spatial working memory capacity and initial variability in strategy use on analogical reasoning development. Results indicated that children in both treatment groups improved but that gains were greater for those who had received training. Training also reduced the influence of children's initial variability in the use of analogical strategies with the degree of improvement in reasoning largely unrelated to working memory capacity. Findings from this study demonstrate the value of a microgenetic research method and the use of multilevel analysis to examine inter- and intra-individual change in problem-solving processes. Copyright © 2016 Elsevier Inc. All rights reserved.
DEFF Research Database (Denmark)
Damgaard, M.; Andersen, L.V.; Ibsen, L.B.
2015-01-01
The reliability of offshore wind turbines is highly influenced by the uncertainties related to the subsoil conditions. Traditionally, the evaluation of the dynamic structural behaviour is based on a computational model with deterministic soil properties. Using this approach, however, provides...... limited insight into the variation of the estimate of the inherent modal properties and loads. In this paper, a comprehensive study is performed on the dynamic behaviour of an offshore wind turbine installed on a monopile foundation. Based on consistent lumped-parameter models calibrated to semi......-analytical impedance functions of a monopile embedded in a stochastic linear viscoelastic soil layer, fully coupled aero-hydro-elastic simulations are conducted in the nonlinear multi-body code Hawc2. The probabilistic analysis accounts for the uncertainty of soil properties (e.g. damping and stiffness) and relies...
Modeling short-term dynamics and variability for realistic interactive facial animation.
Stoiber, Nicolas; Breton, Gaspard; Seguier, Renaud
2010-01-01
Modern modeling and rendering techniques have produced nearly photorealistic face models, but truly expressive digital faces also require natural-looking movements. Virtual characters in today's applications often display unrealistic facial expressions. Indeed, facial animation with traditional schemes such as keyframing and motion capture demands expertise. Moreover, the traditional schemes aren't adapted to interactive applications that require the real-time generation of context-dependent movements. A new animation system produces realistic expressive facial motion at interactive speed. The system relies on a set of motion models controlling facial-expression dynamics. The models are fitted on captured motion data and therefore retain the dynamic signature of human facial expressions. They also contain a nondeterministic component that ensures the variety of the long-term visual behavior. This system can efficiently animate any synthetic face. The video illustrates interactive use of a system that generates facial-animation sequences.
Climate states and variability of Arctic ice and water dynamics during 1946–1997
Proshutinsky, Andrey Y.; Polyakov, Igor V; Johnson, Mark A.
1999-01-01
Recently observed changes in the Arctic have highlighted the need for a better understanding of Arctic dynamics. This research addresses that need and is also motivated by the recent finding of two regimes of Arctic ice - ocean wind-driven circulation. In this paper, we demonstrate that during 1946-1997 the Arctic environmental parameters have oscillated with a period of 10-15 years. Our results reveal significant differences among atmosphere, ice, and ocean processes during the anticyclonic ...
Zhong, Yuru; Jan, Kung-Ming; Ju, Ki Hwan; Chon, Ki H
2006-09-01
The ratio between low-frequency (LF) and high-frequency (HF) spectral power of heart rate has been used as an approximate index for determining the autonomic nervous system (ANS) balance. An accurate assessment of the ANS balance can only be achieved if clear separation of the dynamics of the sympathetic and parasympathetic nervous activities can be obtained, which is a daunting task because they are nonlinear and have overlapping dynamics. In this study, a promising nonlinear method, termed the principal dynamic mode (PDM) method, is used to separate dynamic components of the sympathetic and parasympathetic nervous activities on the basis of ECG signal, and the results are compared with the power spectral approach to assessing the ANS balance. The PDM analysis based on the 28 subjects consistently resulted in a clear separation of the two nervous systems, which have similar frequency characteristics for parasympathetic and sympathetic activities as those reported in the literature. With the application of atropine, in 13 of 15 supine subjects there was an increase in the sympathetic-to-parasympathetic ratio (SPR) due to a greater decrease of parasympathetic than sympathetic activity (P=0.003), and all 13 subjects in the upright position had a decrease in SPR due to a greater decrease of sympathetic than parasympathetic activity (Pparasympathetic and sympathetic nervous systems. The culprit is equivalent decreases in both the sympathetic and parasympathetic activities irrespective of the pharmacological blockades. These findings suggest that the PDM shows promise as a noninvasive and quantitative marker of ANS imbalance, which has been shown to be a factor in many cardiac and stress-related diseases.
Non-Linear Dynamics of Macroeconomic Variables: The Case of Greece
Sophia Kassapi
2015-01-01
This paper is part of an ongoing doctoral dissertation. It examines the long run relationship between government spending on education, GDP growth and educational enrollments in all levels, for Greece in the years 1960-2012, leveling up to capture more complex dependent dynamics in time series. OECD Indicator A11 shows that, life satisfaction, civic engagement and health. are at the same level for adults with tertiary education and adults with upper secondary education for Greece. Having cond...
Mixa, T.; Fritts, D. C.; Laughman, B.; Wang, L.; Kantha, L. H.
2015-12-01
Multiple observations provide compelling evidence that gravity wave dissipation events often occur in multi-scale environments having highly-structured wind and stability profiles extending from the stable boundary layer into the mesosphere and lower thermosphere. Such events tend to be highly localized and thus yield local energy and momentum deposition and efficient secondary gravity wave generation expected to have strong influences at higher altitudes [e.g., Fritts et al., 2013; Baumgarten and Fritts, 2014]. Lidars, radars, and airglow imagers typically cannot achieve the spatial resolution needed to fully quantify these small-scale instability dynamics. Hence, we employ high-resolution modeling to explore these dynamics in representative environments. Specifically, we describe numerical studies of gravity wave packets impinging on a sheet of high stratification and shear and the resulting instabilities and impacts on the gravity wave amplitude and momentum flux for various flow and gravity wave parameters. References: Baumgarten, Gerd, and David C. Fritts (2014). Quantifying Kelvin-Helmholtz instability dynamics observed in noctilucent clouds: 1. Methods and observations. Journal of Geophysical Research: Atmospheres, 119.15, 9324-9337. Fritts, D. C., Wang, L., & Werne, J. A. (2013). Gravity wave-fine structure interactions. Part I: Influences of fine structure form and orientation on flow evolution and instability. Journal of the Atmospheric Sciences, 70(12), 3710-3734.
Consensus Emerging from the Bottom-up: the Role of Cognitive Variables in Opinion Dynamics
Giardini, Francesca; Vilone, Daniele; Conte, Rosaria
2015-09-01
The study of opinions - e.g., their formation and change, and their effects on our society - by means of theoretical and numerical models has been one of the main goals of sociophysics until now, but it is one of the defining topics addressed by social psychology and complexity science. Despite the flourishing of different models and theories, several key questions still remain unanswered. The aim of this paper is to provide a cognitively grounded computational model of opinions in which they are described as mental representations and defined in terms of distinctive mental features. We also define how these representations change dynamically through different processes, describing the interplay between mental and social dynamics of opinions. We present two versions of the model, one with discrete opinions (voter model-like), and one with continuous ones (Deffuant-like). By means of numerical simulations, we compare the behaviour of our cognitive model with the classical sociophysical models, and we identify interesting differences in the dynamics of consensus for each of the models considered.
Discontinuity of Gas-dynamic Variables in the Center of the Compression Wave
Directory of Open Access Journals (Sweden)
Pavel Viktorovich Bulat
2014-12-01
Full Text Available The purpose of research-the study of the flow in the center of the centered isentropic compression waves. Gas-dynamic discontinuities cover shocks, shockwaves, interfaces and sliding surfaces and also the center of the centered compression wave one-dimensional and two-dimensional. For a long time there has been no analysis of the shockwave structures arising in the center of compression waves. At the same time, the problem of development of supersonic and hypersonic air inlets demands to consider the process of the stream isentropic compression. This problem is connected (three-dimensional case to the problem of arising inside the streams of hinged shocks as opposite to the usual discontinuities not resulted by interaction of supersonic streams, waves and discontinuities, but like from nowhere. This study sets the problem for study in the terms of the developed theory of the interference of gas-dynamic discontinuities of the area of existing solutions for the structures of possible types. We have obtained the relations describing the parameters in the center of the compression wave. We have considered the neutral polar of neither compression meeting the case when in the center of the compression wave there neither shocks nor depression waves. The analysis of properties of the centered compression wave adds to the theory of stationary gas-dynamic discontinuities. We have specified the borders of the shock structure existence area optimal for development of supersonic diffusers.
Co-existing hidden attractors in a radio-physical oscillator system
DEFF Research Database (Denmark)
Kuznetsov, A. P.; Kuznetsov, S. P.; Mosekilde, Erik
2015-01-01
, this paper describes the formation of several different coexisting sets of hidden attractors, including the simultaneous presence of a pair of coinciding quasiperiodic attractors and of two mutually symmetric chaotic attractors. We follow the dynamics of the system as a function of the basic oscillator...
Variability and trends in dynamical forcing of tropical lower stratospheric temperatures
Directory of Open Access Journals (Sweden)
S. Fueglistaler
2014-05-01
Full Text Available We analyse the relation between tropical lower stratospheric temperatures and dynamical forcing over the period 1980–2011 using NCEP, MERRA and ERA-Interim reanalyses. The tropical mean thermodynamic energy equation with Newtonian cooling for radiation is forced with two dynamical predictors: (i the average eddy heat flux of both hemispheres; and (ii tropical upwelling estimated from momentum balance following Randel et al. (2002. The correlation (1995–2011 for deseasonalised tropical average temperatures at 70 hPa with the eddy heat flux based predictor is 0.84 for ERA-Interim (0.77 for the momentum balance calculation, and 0.87 for MERRA. The eddy heat flux based predictor indicates a dynamically forced cooling of the tropics of ∼−0.1 K decade−1 (∼−0.2 K decade−1 excluding volcanic periods for the period 1980–2011 in MERRA and ERA-Interim. ERA-Interim eddy heat fluxes drift slightly relative to MERRA in the 2000's, possibly due to onset of GPS temperature data assimilation. While NCEP gives a small warming trend, all 3 reanalyses show a similar seasonality, with strongest cooling in January/February (∼−0.4 K decade−1, from northern hemispheric forcing and October (∼−0.3 K decade−1, from southern hemispheric forcing. Months preceding and following the peaks in cooling trends show pronounced smaller, or even warming, trends. Consequently, the seasonality in the trends arises in part due to a temporal shift in eddy activity. Over all months, the Southern Hemisphere contributes more to the tropical cooling in both MERRA and ERA-Interim. The residual time series (observed minus estimate of dynamically forced temperature are well correlated between ERA-Interim and MERRA, with differences largely due to temperature differences. The residual time series is dominated by the modification of the radiative balance by volcanic aerosol following the eruption of El Chichon (maximum warming of ∼3 K at 70 hPa and Pinatubo
Imaginary part of action, Future functioning as hidden variables
Nielsen, H B
2009-01-01
A model -- by myself and Masao Ninomiya -- which in principle predicts the initial conditions in a way as to minimze a certain functional of the history of the Universe through both past and future -- a functional conceived of as an imaginary part of the action -- is suggested to be also helpful in solving some problems for quantum mechanics. Especially as our model almost makes it possible in principle to calculate the full history of the universe, it even makes it in principle calculable, which one among several measurement results in a quantum experiment will actually be realized! Our "complex action model" thus is a special case of superdeterminism - in Bells way - and does not have true causality, but rather even in some cases true backward causation. In fact we claim in our model that the SSC (Superconducting Supercollider) were stopped by the US Congress due to the backward causation from the big amounts of Higgs particles, which it would have produced, if it had been allowed to run. The noumenon ("das...
Imaginary part of action, Future functioning as hidden variables
Nielsen, H.B.
2009-01-01
A model -- by myself and Masao Ninomiya -- which in principle predicts the initial conditions in a way as to minimze a certain functional of the history of the Universe through both past and future -- a functional conceived of as an imaginary part of the action -- is suggested to be also helpful in solving some problems for quantum mechanics. Especially as our model almost makes it possible in principle to calculate the full history of the universe, it even makes it in principle calculable, w...
Ortega Cisneros, Kelly; Smit, Albertus J; Laudien, Jürgen; Schoeman, David S
2011-01-01
Sandy beach ecological theory states that physical features of the beach control macrobenthic community structure on all but the most dissipative beaches. However, few studies have simultaneously evaluated the relative importance of physical, chemical and biological factors as potential explanatory variables for meso-scale spatio-temporal patterns of intertidal community structure in these systems. Here, we investigate macroinfaunal community structure of a micro-tidal sandy beach that is located on an oligotrophic subtropical coast and is influenced by seasonal estuarine input. We repeatedly sampled biological and environmental variables at a series of beach transects arranged at increasing distances from the estuary mouth. Sampling took place over a period of five months, corresponding with the transition between the dry and wet season. This allowed assessment of biological-physical relationships across chemical and nutritional gradients associated with a range of estuarine inputs. Physical, chemical, and biological response variables, as well as measures of community structure, showed significant spatio-temporal patterns. In general, bivariate relationships between biological and environmental variables were rare and weak. However, multivariate correlation approaches identified a variety of environmental variables (i.e., sampling session, the C∶N ratio of particulate organic matter, dissolved inorganic nutrient concentrations, various size fractions of photopigment concentrations, salinity and, to a lesser extent, beach width and sediment kurtosis) that either alone or combined provided significant explanatory power for spatio-temporal patterns of macroinfaunal community structure. Overall, these results showed that the macrobenthic community on Mtunzini Beach was not structured primarily by physical factors, but instead by a complex and dynamic blend of nutritional, chemical and physical drivers. This emphasises the need to recognise ocean-exposed sandy
Ortega Cisneros, Kelly; Smit, Albertus J.; Laudien, Jürgen; Schoeman, David S.
2011-01-01
Sandy beach ecological theory states that physical features of the beach control macrobenthic community structure on all but the most dissipative beaches. However, few studies have simultaneously evaluated the relative importance of physical, chemical and biological factors as potential explanatory variables for meso-scale spatio-temporal patterns of intertidal community structure in these systems. Here, we investigate macroinfaunal community structure of a micro-tidal sandy beach that is located on an oligotrophic subtropical coast and is influenced by seasonal estuarine input. We repeatedly sampled biological and environmental variables at a series of beach transects arranged at increasing distances from the estuary mouth. Sampling took place over a period of five months, corresponding with the transition between the dry and wet season. This allowed assessment of biological-physical relationships across chemical and nutritional gradients associated with a range of estuarine inputs. Physical, chemical, and biological response variables, as well as measures of community structure, showed significant spatio-temporal patterns. In general, bivariate relationships between biological and environmental variables were rare and weak. However, multivariate correlation approaches identified a variety of environmental variables (i.e., sampling session, the C∶N ratio of particulate organic matter, dissolved inorganic nutrient concentrations, various size fractions of photopigment concentrations, salinity and, to a lesser extent, beach width and sediment kurtosis) that either alone or combined provided significant explanatory power for spatio-temporal patterns of macroinfaunal community structure. Overall, these results showed that the macrobenthic community on Mtunzini Beach was not structured primarily by physical factors, but instead by a complex and dynamic blend of nutritional, chemical and physical drivers. This emphasises the need to recognise ocean-exposed sandy
Davis, S.; Sudheer, K. P.; Gunthe, S. S.
2015-12-01
Indian summer monsoon rainfall (ISMR; June to September), which constitutes around 80% of India's annual rainfall, has shown an increasing trend in intensity and frequency of extreme events (Goswami et al., 2006). It is a widely recognized fact that the increasing temperature in association with anthropogenic activities can affect the hydrological cycle, which leads to extreme events. In addition a shift in extremes of the spatial pattern of ISMR has recently been observed (Ghosh et al., 2011). Such changes in rainfall on temporal and spatial scale can further affect the stream flow over a given region subsequently making water resource management a difficult task (Mondal and Mujumdar, 2015). The hydrological models used for the stream flow estimation are dependent on various climate variables as input data. These climate variables could be obtained through either observational networks or climate model outputs. Due to the scarcity of the observational data over the Indian region and the coarse resolution of global climate model output, which is used as input to hydrologic models, large uncertainties are introduced in stream flow output (Overgaard et al., 2007). In the present study we have used the Weather Research and Forecasting (WRF) model (Skamarock et al. 2008) to downscale the essential climate variables (surface temperature, precipitation, relative humidity, etc.) as an input for its coupled hydrological extension, WRF Hydro (NCAR user's guide). We will present the results obtained from the WRF-hydro simulation to estimate the stream flow over the Thamirabarani river basin in Southern Tropical Indian region. Preliminary simulations using WRF to estimate the precipitation showed the reasonable quantitative agreement with observed values. An attempt will be made to demonstrate how these results can further be used for developing flood-forecasting techniques and for local regional water resource management.
Dynamics of spectral components of heart rate variability during changes in autonomic balance
DEFF Research Database (Denmark)
Højgaard, M V; Holstein-Rathlou, N H; Agner, E;
1998-01-01
Frequency domain analysis of heart rate variability (HRV) has been proposed as a semiquantitative method for assessing activities in the autonomic nervous system. We examined whether absolute powers, normalized powers, and the low frequency-to-high frequency ratio (LF/HF) derived from the HRV power...... spectrum could detect shifts in autonomic balance in a setting with low sympathetic nervous tone. Healthy subjects were examined for 3 h in the supine position during 1) control conditions (n = 12), 2) acute beta-blockade (n = 11), and 3) chronic beta-blockade (n = 10). Heart rate fell during the first 40...
Secular spring rainfall variability at local scale over Ethiopia: trend and associated dynamics
Tsidu, Gizaw Mengistu
2016-07-01
Spring rainfall secular variability is studied using observations, reanalysis, and model simulations. The joint coherent spatio-temporal secular variability of gridded monthly gauge rainfall over Ethiopia, ERA-Interim atmospheric variables and sea surface temperature (SST) from Hadley Centre Sea Ice and SST (HadISST) data set is extracted using multi-taper method singular value decomposition (MTM-SVD). The contemporaneous associations are further examined using partial Granger causality to determine presence of causal linkage between any of the climate variables. This analysis reveals that only the northwestern Indian Ocean secular SST anomaly has direct causal links with spring rainfall over Ethiopia and mean sea level pressure (MSLP) over Africa inspite of the strong secular covariance of spring rainfall, SST in parts of subtropical Pacific, Atlantic, Indian Ocean and MSLP. High secular rainfall variance and statistically significant linear trend show consistently that there is a massive decline in spring rain over southern Ethiopia. This happened concurrently with significant buildup of MSLP over East Africa, northeastern Africa including parts of the Arabian Peninsula, some parts of central Africa and SST warming over all ocean basins with the exception of the ENSO regions. The east-west pressure gradient in response to the Indian Ocean warming led to secular southeasterly winds over the Arabian Sea, easterly over central Africa and equatorial Atlantic. These flows weakened climatological northeasterly flow over the Arabian Sea and southwesterly flow over equatorial Atlantic and Congo basins which supply moisture into the eastern Africa regions in spring. The secular divergent flow at low level is concurrent with upper level convergence due to the easterly secular anomalous flow. The mechanisms through which the northwestern Indian Ocean secular SST anomaly modulates rainfall are further explored in the context of East Africa using a simplified atmospheric
Directory of Open Access Journals (Sweden)
Blagica Novkovska
2016-12-01
Full Text Available Hidden economy presents a big concern for both developing and developed countries. Of particular interest is precise determination of the temporal pattern of hidden for small developing economies, which exhibit many peculiarities. Several methods for estimation of hidden economy are effectively used in economic research. Appropriate model based on some of these methods for small developing economies is required. Modified electric energy household consumption model is proposed in this work. Using this model, temporal variations of hidden economy in Republic of Macedonia were calculated for the period 1992–2014. For the sub-period 1999–2007 the obtained values are in excellent agreement with values reported in literature obtained by dynamic multiple indicators multiple causes method, proving that the method proposed in this work produces highly relevant results. Thus obtained temporal pattern of the hidden economy in Macedonia, using deconvolution in Gaussians, is described by five contributions: baseline at 32% and four Gaussian peaks corresponding to hyperinflation, Kosovo conflict, security crisis in Macedonia and banking crisis. After the expiration of the effects of these shocks, hidden economy approaches the baseline at about 32 %. It is proposed to use this modified method for estimating size of hidden economy in various small economies.
Probing hidden sector photons through the Higgs window
Energy Technology Data Exchange (ETDEWEB)
Ahlers, M. [Oxford Univ. (United Kingdom). Rudolf Peierls Centre for Theoretical Physics; Jaeckel, J. [Durham Univ. (United Kingdom). Inst. for Particle Physics and Phenomenology; Redondo, J.; Ringwald, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2008-07-15
We investigate the possibility that a (light) hidden sector extra photon receives its mass via spontaneous symmetry breaking of a hidden sector Higgs boson, the so-called hidden-Higgs. The hidden-photon can mix with the ordinary photon via a gauge kinetic mixing term. The hidden-Higgs can couple to the Standard Model Higgs via a renormalizable quartic term - sometimes called the Higgs Portal. We discuss the implications of this light hidden-Higgs in the context of laser polarization and light-shining-through-the-wall experiments as well as cosmological, astrophysical, and non-Newtonian force measurements. For hidden-photons receiving their mass from a hidden-Higgs we find in the small mass regime significantly stronger bounds than the bounds on massive hidden sector photons alone. (orig.)
Cloud cover anomalies at middle latitudes: Links to troposphere dynamics and solar variability
Veretenenko, S.; Ogurtsov, M.
2016-11-01
In this work we study links between low cloud anomalies (LCA) at middle latitudes of the Northern and Southern hemispheres and galactic cosmic ray (GCR) variations used as a proxy of solar variability on the decadal time scale. It was shown that these links are not direct, but realized through GCR/solar activity phenomena influence on the development of extratropical baric systems (cyclones and troughs) which form cloud field. The violation of a positive correlation between LCA and GCR intensity which was observed in the 1980s-1990s occurred simultaneously in the Northern and Southern hemispheres in the early 2000s and coincided with the sign reversal of GCR effects on troposphere circulation. It was suggested that a possible reason for the correlation reversal between cyclonic activity at middle latitudes and GCR fluxes is the change of the stratospheric polar vortex intensity which influences significantly the troposphere-stratosphere coupling. The evidences for a noticeable weakening of the polar vortices in the Arctic and Antarctic stratosphere in the early 2000s are provided. The results obtained suggest an important role of the polar vortex evolution as a reason for a temporal variability of solar activity effects on the lower atmosphere.
Impact of delayed spark restrike on the dynamics of cyclic variability in dilute SI combustion
Energy Technology Data Exchange (ETDEWEB)
Kaul, Brian C [ORNL; Wagner, Robert M [ORNL
2016-01-01
Spark-ignition (SI) engines can derive substantial efficiency gains from operation at high dilution levels. Additionally, the use of exhaust gas recirculation (EGR) for charge dilution also maintains compatibility with three-way catalysts by allowing stoichiometric operation. However, running high dilution levels increases the occurrence of misfires and partial burns, which induce higher levels of cyclic-variability in engine operation. This variability has been shown to have both stochastic and deterministic components. Factors such as in-cylinder turbulence and mixing-variations can be classified as stochastic; while, charge composition is the major source of the deterministic component through its non-linear effect on ignition and flame propagation characteristics. The use of these deterministic components has been previously explored to construct next-cycle control approaches that would allow stable operation near the edge of stability. Building on that work, this paper aims to understand the effect of spark strategies, specifically the use of a second spark (restrike) after the main spark, on engine operation at high dilution levels that were achieved using both excess air (i.e. lean combustion) and EGR.
Tornador, Cristian; Falcón, Carles; López‐Solà, Marina; Hernández‐Ribas, Rosa; Pujol, Jesús; Menchón, José M.; Ritter, Petra; Cardoner, Narcis; Soriano‐Mas, Carles; Deco, Gustavo
2016-01-01
Abstract Resting‐state fMRI (RS‐fMRI) has become a useful tool to investigate the connectivity structure of mental health disorders. In the case of major depressive disorder (MDD), recent studies regarding the RS‐fMRI have found abnormal connectivity in several regions of the brain, particularly in the default mode network (DMN). Thus, the relevance of the DMN to self‐referential thoughts and ruminations has made the use of the resting‐state approach particularly important for MDD. The majority of such research has relied on the grand averaged functional connectivity measures based on the temporal correlations between the BOLD time series of various brain regions. We, in our study, investigated the variations in the functional connectivity over time at global and local level using RS‐fMRI BOLD time series of 27 MDD patients and 27 healthy control subjects. We found that global synchronization and temporal stability were significantly increased in the MDD patients. Furthermore, the participants with MDD showed significantly increased overall average (static) functional connectivity (sFC) but decreased variability of functional connectivity (vFC) within specific networks. Static FC increased to predominance among the regions pertaining to the default mode network (DMN), while the decreased variability of FC was observed in the connections between the DMN and the frontoparietal network. Hum Brain Mapp 37:2918–2930, 2016. © 2016 Wiley Periodicals, Inc. PMID:27120982
Arain, M. A.
2015-12-01
Climate variability, extreme weather events, forest age and management history impacts carbon sequestration in forest ecosystems. A variety of measurement techniques such as eddy covariance, dendrochronology, automatic soil CO2 chambers and remote sensing are employed fully understand forest carbon dynamics. Here, we present carbon flux measurements from 2003-2014 in a 76-year old managed temperate pine ((-Pinus strobus L.) forest, near Lake Erie in southern Ontario, Canada. Forest was partially thinned (30% tree harvested) in 1983 and 2012. The thinning in 2012 did not significantly impact carbon fluxes as post-thinning fluxes were within the range of inter-annual variability. Mean annual post-thinning (2012-2104) gross ecosystem productivity (GEP) measure by the eddy covariance technique was 1518 ± 78 g C m-2 year-1 as compared to pre-thinning (2003-2011) GEP of 1384 ± 121 g C m-2·year-1. Over the same period, mean post-thinning net ecosystem productivity (NEP) was 185 ± 75 g C m-2 year-1 as compared to post-thinning NEP of 180 ± 70 g C m-2 year-1, indicating that pre-thinning NEP was not significantly different than post-thinning NEP. Only post-thinning mean annual ecosystem respiration (Re; 1322 ± 54 g C m-2 year-1) was higher than pre-thinning Re (1195 ± 101 g C m-2 year-1). Soil CO2 efflux measurements showed similar trends. We also evaluated the impacts of climate variability and management regime on the full life cycle of the forest using annual radial tree-ring growths from 15 trees and compared them with historical climate (temperature and precipitation) data. While the annual growth rates displayed weak correlation with long-term climatic records, the growth was generally reduced during years with extreme drought (-36% of mean annual precipitation) and extreme temperature variability (±0.6 - 1.0°C). Overall, forest was more sensitive to management regime than climate variability. It showed higher growth stress during low light condition after
Khandoker, Ahsan H; Taylor, Simon B; Karmakar, Chandan K; Begg, Rezaul K; Palaniswami, Marimuthu
2008-08-01
Current research applying variability measures of gait parameters has demonstrated promise for helping to solve one of the "holy grails" of geriatric research by defining markers that can be used to prospectively identify persons at risk of falling . The minimum toe clearance (MTC) event occurs during the leg swing phase of the gait cycle and is a task highly sensitive to the spatial and balance control properties of the locomotor system. The aim of this study is to build upon the current state of research by investigating the magnitude and dynamic structure from the MTC time series fluctuations due to aging and locomotor disorder. Thirty healthy young (HY), 27 healthy elderly (HE), and 10 falls risk (FR) elderly individuals (who presented a prior history of trip-related falls) participated in treadmill walking for at least 10 min at their preferred speed. Continuous MTC data were collected and the first 512 data points were analyzed. The following variability indices were quantified: 1) MTC mean and standard deviation (SD), 2) PoincarE plot indices of MTC variability (SD1, SD2, SD1/SD2), 3) a wavelet based multiscale exponent beta to describe the dynamic structure of MTC fluctuations, and 4) detrended fluctuation analysis exponent alpha to investigate the presence of long-range correlations in MTC time series data. Results showed that stride-to-stride MTC time series has a nonlinear structure in all three groups when compared against randomly shuffled surrogate MTC data. Test on aging effects showed the MTC central tendency was significantly lower (p 0.05). There were, however, significant differences between HY and FR for beta (between scale 1 and 2; p < 0.01) and alpha (p < 0.05). Out of all the variability measures applied, beta(Wv2-4), SD1/SD2, SD2 of critical MTC parameter were found to be potential markers to be able to reliably identify FR from HE subjects. Further research is required to understand the mechanisms underlying the cause of MTC variability.
Rommelfanger, D M; Offord, C P; Dev, J; Bajzer, Z; Vile, R G; Dingli, D
2012-05-01
Tumor selective, replication competent viruses are being tested for cancer gene therapy. This approach introduces a new therapeutic paradigm due to potential replication of the therapeutic agent and induction of a tumor-specific immune response. However, the experimental outcomes are quite variable, even when studies utilize highly inbred strains of mice and the same cell line and virus. Recognizing that virotherapy is an exercise in population dynamics, we utilize mathematical modeling to understand the variable outcomes observed when B16ova malignant melanoma tumors are treated with vesicular stomatitis virus in syngeneic, fully immunocompetent mice. We show how variability in the initial tumor size and the actual amount of virus delivered to the tumor have critical roles on the outcome of therapy. Virotherapy works best when tumors are small, and a robust innate immune response can lead to superior tumor control. Strategies that reduce tumor burden without suppressing the immune response and methods that maximize the amount of virus delivered to the tumor should optimize tumor control in this model system.
Laranjeira, Francisco Ferraz; Silva, Suely Xavier de Brito; de Andrade, Eduardo Chumbinho; Almeida, Décio de Oliveira; da Silva, Tibério Santos Martins; Soares, Ana Cristina Fermino; Freitas-Astúa, Juliana
2015-08-01
Brevipalpus phoenicis (Geijskes) is a cosmopolitan and polyphagous mite that transmits important phytoviruses, such as coffee ringspot virus, passion fruit green spot virus and Citrus leprosis virus C. To characterise the dynamics of the probability and the rate of B. phoenicis infestation in response to edaphic and climatic factors, monthly inspections were performed in nine orchards in a citrus region of the State of Bahia, Brazil, for 35 months. Three fruits per plant were examined using a magnifying glass (10×) on 21 plants distributed along a "W"-shaped path in each orchard. Meteorological data were collected from a conventional station. To determine the correlations among the climatic variables, the data were analysed using Spearman correlations. Variables were selected by principal component analysis, and those that contributed the most to differentiate the groups were evaluated via a Mann-Whitney test. Using the quantile-quantile method, the limit values for the following climatic variables were determined: temperature (24.5 °C), photoperiod (12 h), relative humidity (83%), evapotranspiration (71 mm) and rainy days (14 days). The combination of longer days, higher temperatures, lower relative humidity levels and lower evapotranspiration increased the probability of B. phoenicis infestation, whereas successive rain events decreased that risk. Infestation rates were negatively affected by relative humidity levels above 83% and were positively affected by a decreasing available soil-water fraction and increasing insolation and photoperiod.
Energy Technology Data Exchange (ETDEWEB)
Rockhold, M. L.; Yarwood, R. R.; Niemet, M. R.; Bottomley, Peter J.; Brockman, Fred J.; Selker, John S.
2007-06-01
An experimental and numerical investigation was conducted to study the colonization dynamics of a bioluminescent bacterium, Pseudomonas fluorescens HK44, during growth in a porous medium under steady, variably saturated flow conditions. Experiments were conducted in a thin-slab light transmission chamber filled with uniform, translucent quartz sand. Steady, variably saturated flow conditions were established using drip emitters mounted on the top of the chamber, with glucose applied through a central dripper located directly above an inoculated region of the chamber. Periodic pulses of salicylate and a dye tracer were applied to induce bioluminescence of the bacterium to monitor colony expansion and to track changes in the hydraulic and transport properties of the sand. Changes in the apparent water saturation of the sand were quantified by monitoring light transmission through the chamber with a CCD camera. The colonized region expanded laterally by about 15 cm, and upward against the flow by 7-8 cm during the 6-day experiment while apparent saturations in the colonized region decreased by 7-9% and the capillary fringe dropped by ~5 cm. The observed data were reproduced approximately using a numerical model that accounted for the processes of water flow, solute and bacterial transport, cell growth and accumulation, glucose and oxygen consumption, and gas diffusion and exchange. The results of this study illustrate some of the complexities associated with coupled flow, reactive transport, and biological processes in variably saturated porous media, which are not readily observable using other experimental techniques.
Extraordinary variability and sharp transitions in a maximally frustrated dynamic network
Liu, Wenjia; Schmittmann, Beate; Zia, R. K. P.
2013-03-01
Most previous studies of complex networks have focused on single, static networks. However, in the real world, networks are dynamic and interconnected. Inspired by the presence of extroverts and introverts in the general population, we investigate a highly simplified model of a social network, involving two types of nodes: one preferring the highest degree possible, and one preferring no connections whatsoever. There are only two control parameters in the model: the number of ``introvert'' and ``extrovert'' nodes, NI and NE. Our key findings are as follows: As a function of NI and NE, the system exhibits a highly unusual transition, displaying extraordinary fluctuations (as in 2nd order transitions) and discontinuous jumps (characteristic of 1st order transitions). Most remarkably, the system can be described by an Ising-like Hamiltonian with long-range multi-spin interactions and some of its properties can be obtained analytically. This is in stark contrast with other dynamic network models which rely almost exclusively on simulations. NSF-DMR-1005417/1244666 and and ICTAS Virginia Tech
A portable device to assess underwater changes of cardio dynamic variables by impedance cardiography
Tocco, F.; Crisafulli, A.; Marongiu, E.; Milia, R.; Kalb, A.; Concu, A.
2012-12-01
Data concerning heart rate (HR), stroke volume (SV), and cardiac output (CO) during dynamic apnoea (DA) were collected from 10 healthy male, elite divers by means of an impedance cardiograph adapted to the underwater environment (C. O. Re., from 2C Technologies Inc, Italy). Three trials were performed by the divers in a 3-m-deep pool with a water temperature of 25°C: 3-minute head-out immersion during normal breathing (A), till exhaustion immersed at the surface (B) and at 3m depth (C). Both B and C conditions did not led to changes in HR, SV and CO compared to A. Data indicate that typical diving response consisting in a reduction of HR, SV and CO was not present during DA, probably due to sympathetic activation induced by exercise during DA, which partially obscured the effects of the diving response. Moreover, this study highlights the innovative role of our portable, impedance cardiography device, i.e. the C. O. Re., in easily assessing cardiodynamic changes in subjects engaged in exercise schedules including phases of underwater, dynamic apnoea.
Quantum dynamics of a driven two-level molecule with variable dephasing
Grandi, Samuele; Major, Kyle D.; Polisseni, Claudio; Boissier, Sebastien; Clark, Alex S.; Hinds, E. A.
2016-12-01
The longitudinal (Γ1) and transverse (Γ2) decay rates of a two-level quantum system have a profound influence on its evolution. Atomic systems with Γ2=1/2 Γ1 have been studied extensively, but with the rise of solid-state quantum devices it is also important to consider the effect of stronger transverse relaxation due to interactions with the solid environment. Here we study the quantum dynamics of a single organic dye molecule driven by a laser. We measure the variation of Γ2 with temperature and determine the activation energy for thermal dephasing of the optical dipole. Then we measure the second-order correlation function g(2 )(τ ) of the light emitted by the molecule for various ratios Γ2/Γ1 and saturation parameters S . We show that the general solution to the optical Bloch equations accurately describes the observed quantum dynamics over a wide range of these parameters, and we discuss the limitations of the various approximate expressions for g(2 )(τ ) that appear in the literature.
Daliakopoulos, Ioannis; Tsanis, Ioannis
2017-04-01
Mitigating the vulnerability of Mediterranean rangelands against degradation is limited by our ability to understand and accurately characterize those impacts in space and time. The Normalized Difference Vegetation Index (NDVI) is a radiometric measure of the photosynthetically active radiation absorbed by green vegetation canopy chlorophyll and is therefore a good surrogate measure of vegetation dynamics. On the other hand, meteorological indices such as the drought assessing Standardised Precipitation Index (SPI) are can be easily estimated from historical and projected datasets at the global scale. This work investigates the potential of driving Random Forest (RF) models with meteorological indices to approximate NDVI-based vegetation dynamics. A sufficiently large number of RF models are trained using random subsets of the dataset as predictors, in a bootstrapping approach to account for the uncertainty introduced by the subset selection. The updated E-OBS-v13.1 dataset of the ENSEMBLES EU FP6 program provides observed monthly meteorological input to estimate SPI over the Mediterranean rangelands. RF models are trained to depict vegetation dynamics using the latest version (3g.v1) of the third generation GIMMS NDVI generated from NOAA's Advanced Very High Resolution Radiometer (AVHRR) sensors. Analysis is conducted for the period 1981-2015 at a gridded spatial resolution of 25 km. Preliminary results demonstrate the potential of machine learning algorithms to effectively mimic the underlying physical relationship of drought and Earth Observation vegetation indices to provide estimates based on precipitation variability.
Musammil, N M; Porsezian, K; Subha, P A; Nithyanandan, K
2017-02-01
We investigate the dynamics of vector dark solitons propagation using variable coefficient coupled nonlinear Schrödinger (Vc-CNLS) equation. The dark soliton propagation and evolution dynamics in the inhomogeneous system are studied analytically by employing the Hirota bilinear method. It is apparent from our asymptotic analysis that the collision between the dark solitons is elastic in nature. The various inhomogeneous effects on the evolution and interaction between dark solitons are explored, with a particular emphasis on nonlinear tunneling. It is found that the tunneling of the soliton depends on a condition related to the height of the barrier and the amplitude of the soliton. The intensity of the tunneling soliton either forms a peak or a valley, thus retaining its shape after tunneling. For the case of exponential background, the soliton tends to compress after tunneling through the barrier/well. Thus, a comprehensive study of dark soliton pulse evolution and propagation dynamics in Vc-CNLS equation is presented in the paper.
Vincenzi, Simone; Mangel, Marc; Jesensˇek, Dusˇan; Garza, John C; Crivelli, Alain J
2016-10-01
Understanding the causes of within- and among-population differences in vital rates, life histories, and population dynamics is a central topic in ecology. To understand how within- and among-population variation emerges, we need long-term studies that include episodic events and contrasting environmental conditions, data to characterize individual and shared variation, and statistical models that can tease apart shared and individual contribution to the observed variation. We used long-term tag-recapture data to investigate and estimate within- and among-population differences in vital rates, life histories, and population dynamics of marble trout Salmo marmoratus, an endemic freshwater salmonid with a narrow range. Only ten populations of pure marble trout persist in headwaters of Alpine rivers in western Slovenia. Marble trout populations are also threatened by floods and landslides, which have already caused the extinction of two populations in recent years. We estimated and determined causes of variation in growth, survival, and recruitment both within and among populations, and evaluated trade-offs between them. Specifically, we estimated the responses of these traits to variation in water temperature, density, sex, early life conditions, and extreme events. We found that the effects of population density on traits were mostly limited to the early stages of life and that growth trajectories were established early in life. We found no clear effects of water temperature on vital rates. Population density varied over time, with flash floods and debris flows causing massive mortalities (>55% decrease in survival with respect to years with no floods) and threatening population persistence. Apart from flood events, variation in population density within streams was largely determined by variation in recruitment, with survival of older fish being relatively constant over time within populations, but substantially different among populations. Marble trout show a fast
Impact of variable body size on pedestrian dynamics by heuristics-based model
Guo, Ning; Hu, Mao-Bin; Jiang, Rui
2017-01-01
In the real world, pedestrians can arch the shoulders or rotate their bodies actively to across the narrow space. The method is helpful to reduce the effective size of the body. In this paper, the impact of variable body size on the direction choice has been investigated by an improved heuristic-based model. In the model, it is assumed that the cost of adjusting body size is a factor in the process to evaluate the optimal direction. In a typical simulation scenario, the pedestrian reluctant to adjust body size will pass by the blocks. On the contrary, the pedestrian caring little about body size will traverse through the exit. There is a direction-choice change behavior between bypass and traverse considering block width and the initial location of the pedestrian.
ON THE DEMAND DYNAMICS OF ELECTRICITY IN GHANA: DO EXOGENOUS NON-ECONOMIC VARIABLES COUNT?
Directory of Open Access Journals (Sweden)
Ishmael Ackah
2014-04-01
Full Text Available The purpose of this study is to identify and quantify the effect of endogenous and exogenous economic factors on electricity demand in Ghana. The Structural Time Series Model is employed due to its ability to capture exogenous non-economic variables. The findings reveal that education has significant effect on electricity consumption in both the short and the long run. Education has inverse relationship with electricity consumption implying that the more consumers are educated, the less electricity they consume. The study also reveals that price changes have less impact on electricity consumption in the short run and that efficiency in electricity consumption has improved since 1971 and will continue for the next twenty years. The study recommends that more public education should be carried out to enhance energy conservation and also, realistic prices should be charge for electricity consumption to allow private investment into the sector.
Lepton mixing from the hidden sector
Ludl, P O
2015-01-01
Experimental results indicate a possible relation between the lepton and quark mixing matrices of the form U_PMNS \\approx V_CKM^\\dagger U_X, where U_X is a matrix with special structure related to the mechanism of neutrino mass generation. We propose a framework which can realize such a relation. The main ingredients of the framework are the double seesaw mechanism, SO(10) Grand Unification and a hidden sector of theory. The latter is composed of singlets (fermions and bosons) of the GUT symmetry with masses between the GUT and Planck scale. The interactions in this sector obey certain symmetries G_hidden. We explore the conditions under which symmetries G_hidden can produce flavour structures in the visible sector. Here the key elements are the basis-fixing symmetry and mediators which communicate information about properties of the hidden sector to the visible one. The interplay of SO(10) symmetry, basis-fixing symmetry identified as Z2 x Z2 and G_hidden can lead to the required form of U_X. A different kin...
Fitting Hidden Markov Models to Psychological Data
Directory of Open Access Journals (Sweden)
Ingmar Visser
2002-01-01
Full Text Available Markov models have been used extensively in psychology of learning. Applications of hidden Markov models are rare however. This is partially due to the fact that comprehensive statistics for model selection and model assessment are lacking in the psychological literature. We present model selection and model assessment statistics that are particularly useful in applying hidden Markov models in psychology. These statistics are presented and evaluated by simulation studies for a toy example. We compare AIC, BIC and related criteria and introduce a prediction error measure for assessing goodness-of-fit. In a simulation study, two methods of fitting equality constraints are compared. In two illustrative examples with experimental data we apply selection criteria, fit models with constraints and assess goodness-of-fit. First, data from a concept identification task is analyzed. Hidden Markov models provide a flexible approach to analyzing such data when compared to other modeling methods. Second, a novel application of hidden Markov models in implicit learning is presented. Hidden Markov models are used in this context to quantify knowledge that subjects express in an implicit learning task. This method of analyzing implicit learning data provides a comprehensive approach for addressing important theoretical issues in the field.
Nield, Joanna M.; McKenna Neuman, Cheryl; O'Brien, Patrick; Bryant, Robert G.; Wiggs, Giles F. S.
2016-12-01
Playas (or ephemeral lakes) can be significant sources of dust, but they are typically covered by salt crusts of variable mineralogy and these introduce uncertainty into dust emission predictions. Despite the importance of crust mineralogy to emission potential, little is known about (i) the effect of short-term changes in temperature and relative humidity on the erodibility of these crusts, and (ii) the influence of crust degradation and mineralogy on wind speed threshold for dust emission. Our understanding of systems where emission is not driven by impacts from saltators is particularly poor. This paper describes a wind tunnel study in which dust emission in the absence of saltating particles was measured for a suite of climatic conditions and salt crust types commonly found on Sua Pan, Botswana. The crusts were found to be non-emissive under climate conditions characteristic of dawn and early morning, as compared to hot and dry daytime conditions when the wind speed threshold for dust emission appears to be highly variable, depending upon salt crust physicochemistry. Significantly, sodium sulphate rich crusts were found to be more emissive than crusts formed from sodium chloride, while degraded versions of both crusts had a lower emission threshold than fresh, continuous crusts. The results from this study are in agreement with in-situ field measurements and confirm that dust emission from salt crusted surfaces can occur without saltation, although the vertical fluxes are orders of magnitude lower (∼10 μg/m/s) than for aeolian systems where entrainment is driven by particle impact.
Flight dynamics of a pterosaur-inspired aircraft utilizing a variable-placement vertical tail.
Roberts, Brian; Lind, Rick; Chatterjee, Sankar
2011-06-01
Mission performance for small aircraft is often dependent on the turn radius. Various biologically inspired concepts have demonstrated that performance can be improved by morphing the wings in a manner similar to birds and bats; however, the morphing of the vertical tail has received less attention since neither birds nor bats have an appreciable vertical tail. This paper investigates a design that incorporates the morphing of the vertical tail based on the cranial crest of a pterosaur. The aerodynamics demonstrate a reduction in the turn radius of 14% when placing the tail over the nose in comparison to a traditional aft-placed vertical tail. The flight dynamics associated with this configuration has unique characteristics such as a Dutch-roll mode with excessive roll motion and a skid divergence that replaces the roll convergence.
Flight dynamics of a pterosaur-inspired aircraft utilizing a variable-placement vertical tail
Energy Technology Data Exchange (ETDEWEB)
Roberts, Brian; Lind, Rick [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611 (United States); Chatterjee, Sankar, E-mail: ricklind@ufl.edu [Department of Geology and Paleontology Museum, Texas Tech University, Lubbock, TX 79409 (United States)
2011-06-15
Mission performance for small aircraft is often dependent on the turn radius. Various biologically inspired concepts have demonstrated that performance can be improved by morphing the wings in a manner similar to birds and bats; however, the morphing of the vertical tail has received less attention since neither birds nor bats have an appreciable vertical tail. This paper investigates a design that incorporates the morphing of the vertical tail based on the cranial crest of a pterosaur. The aerodynamics demonstrate a reduction in the turn radius of 14% when placing the tail over the nose in comparison to a traditional aft-placed vertical tail. The flight dynamics associated with this configuration has unique characteristics such as a Dutch-roll mode with excessive roll motion and a skid divergence that replaces the roll convergence.
Revisiting scalar quark hidden sector in light of 750-GeV diphoton resonance
Chiang, Cheng-Wei; Ibe, Masahiro; Yanagida, Tsutomu T.
2016-05-01
We revisit the model of a CP -even singlet scalar resonance proposed in arXiv:1507.02483 URL"/> , where the resonance appears as the lightest composite state made of scalar quarks participating in hidden strong dynamics. We show that the model can consistently explain the excess of diphoton events with an invariant mass around 750 GeV reported by both the ATLAS and CMS experiments. We also discuss the nature of the charged composite states in the TeV range which accompany to the neutral scalar. Due to inseparability of the dynamical scale and the mass of the resonance, the model also predicts signatures associated with the hidden dynamics such as leptons, jets along with multiple photons at future collider experiments. We also associate the TeV-scale dynamics behind the resonance with an explanation of dark matter.
Chemical and dynamical impacts of stratospheric sudden warmings on Arctic ozone variability
Strahan, S. E.; Douglass, A. R.; Steenrod, S. D.
2016-10-01
We use the Global Modeling Initiative (GMI) chemistry and transport model with Modern-Era Retrospective Analysis for Research and Applications (MERRA) meteorological fields to quantify heterogeneous chemical ozone loss in Arctic winters 2005-2015. Comparisons to Aura Microwave Limb Sounder N2O and O3 observations show the GMI simulation credibly represents the transport processes and net heterogeneous chemical loss necessary to simulate Arctic ozone. We find that the maximum seasonal ozone depletion varies linearly with the number of cold days and with wave driving (eddy heat flux) calculated from MERRA fields. We use this relationship and MERRA temperatures to estimate seasonal ozone loss from 1993 to 2004 when inorganic chlorine levels were in the same range as during the Aura period. Using these loss estimates and the observed March mean 63-90°N column O3, we quantify the sensitivity of the ozone dynamical resupply to wave driving, separating it from the sensitivity of ozone depletion to wave driving. The results show that about 2/3 of the deviation of the observed March Arctic O3 from an assumed climatological mean is due to variations in O3 resupply and 1/3 is due to depletion. Winters with a stratospheric sudden warming (SSW) before mid-February have about 1/3 the depletion of winters without one and export less depletion to the midlatitudes. However, a larger effect on the spring midlatitude ozone comes from dynamical differences between warm and cold Arctic winters, which can mask or add to the impact of exported depletion.
On higher ground: how well can dynamic body acceleration determine speed in variable terrain?
Directory of Open Access Journals (Sweden)
Owen R Bidder
Full Text Available INTRODUCTION: Animal travel speed is an ecologically significant parameter, with implications for the study of energetics and animal behaviour. It is also necessary for the calculation of animal paths by dead-reckoning. Dead-reckoning uses heading and speed to calculate an animal's path through its environment on a fine scale. It is often used in aquatic environments, where transmission telemetry is difficult. However, its adoption for tracking terrestrial animals is limited by our ability to measure speed accurately on a fine scale. Recently, tri-axial accelerometers have shown promise for estimating speed, but their accuracy appears affected by changes in substrate and surface gradients. The purpose of the present study was to evaluate four metrics of acceleration; Overall dynamic body acceleration (ODBA, vectorial dynamic body acceleration (VDBA, acceleration peak frequency and acceleration peak amplitude, as proxies for speed over hard, soft and inclined surfaces, using humans as a model species. RESULTS: A general linear model (GLM showed a significant difference in the relationships between the metrics and speed depending on substrate or surface gradient. When the data from all surface types were considered together, VeDBA had the highest coefficient of determination. CONCLUSIONS: All of the metrics showed some variation in their relationship with speed according to the surface type. This indicates that changes in the substrate or surface gradient during locomotion by animals would produce errors in speed estimates, and also in dead-reckoned tracks if they were calculated from speeds based entirely on a priori calibrations. However, we describe a method by which the relationship between acceleration metrics and speed can be corrected ad hoc, until tracks accord with periodic ground truthed positions, obtained via a secondary means (e.g. VHF or GPS telemetry. In this way, dead-reckoning provides a means to obtain fine scale movement data
Probing Hidden Sector Photons through the Higgs Window.
Ahlers, M.; Jaeckel, J; Redondo, J.; Ringwald, A.
2008-01-01
We investigate the possibility that a (light) hidden sector extra photon receives its mass via spontaneous symmetry breaking of a hidden sector Higgs boson, the so-called hidden-Higgs. The hidden-photon can mix with the ordinary photon via a gauge kinetic mixing term. The hidden-Higgs can couple to the Standard Model Higgs via a renormalizable quartic term - sometimes called the Higgs Portal. We discuss the implications of this light hidden-Higgs in the context of laser polarization and light...
A Dependent Hidden Markov Model of Credit Quality
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Małgorzata Wiktoria Korolkiewicz
2012-01-01
Full Text Available We propose a dependent hidden Markov model of credit quality. We suppose that the "true" credit quality is not observed directly but only through noisy observations given by posted credit ratings. The model is formulated in discrete time with a Markov chain observed in martingale noise, where "noise" terms of the state and observation processes are possibly dependent. The model provides estimates for the state of the Markov chain governing the evolution of the credit rating process and the parameters of the model, where the latter are estimated using the EM algorithm. The dependent dynamics allow for the so-called "rating momentum" discussed in the credit literature and also provide a convenient test of independence between the state and observation dynamics.
Directory of Open Access Journals (Sweden)
Ubaid Yaqoob
2017-01-01
Full Text Available Ferula jaeschkeana Vatke is an important threatened medicinal plant of the Himalayan region. The present study was carried out to determine the impact of the habitat variability and altitudinal gradient on the morphological and reproductive features of the species under study. The species exhibited great variability in its morphological traits under different environmental conditions. The plants were more vigorous and taller at a low altitude site, Kashmir University Botanical Garden (KUBG while the plants of a high altitude site, Gulmarg were shorter. With increased altitude, a significant reduction in the number of umbels per flowering stem, umbellules per umbel and flowers per umbellule occurred. An increase in the number of stigma and anthers was also observed in some plants at higher altitudes. Principal component analysis (PCA revealed that the habitat of KUBG and Dachigam proved relatively better for the growth of F. jaeschkeana. Maximum resources were allocated to the growth and development of the stem followed by root tubers, leaves and inflorescence. Reproductive success of the plant species varied along the altitudinal gradient and ranged from 64% to 72%. Increasing altitude resulted in a decrease in the allocation of biomass to reproductive structures in the form of decreasing dry weight. The total resource budget per plant was maximum in low altitude Drang (572.6 ± 158.36 g and Dachigam (568.4 ± 133.42 g populations and was least in the Gulmarg population (333.4 ± 82.89 g. The reproductive effort was higher (50.83% for the high altitude Gulmarg population. The regression analysis revealed a positive correlation and predicts that plant height has a direct impact on the umbel diameter and leaf length. Our results present a detailed account on the variation of growth characteristics, reproductive success and changes in allocation patterns in relation to the environmental conditions of this valuable medicinal plant species
Interannual and regional variability of ecosystem dynamics in the Black Sea
Fach, Bettina A.; Cannaby, Heather; Dorofeyev, Viktor L.; Kubryakov, Alexander I.; Salihoglu, Baris; Korotaev, Gennady K.; Oguz, Temel; Kideys, Ahmet E.
2013-04-01
A three-dimensional hydrodynamic ecosystem model developed for the Black Sea was used to investigate the influence of anthropogenic drivers on marine ecosystem functioning in the Black Sea with a special focus on regional differences. Data from the ECMWF 40 Year Re-analysis global atmospheric circulation model (ERA-40) were used to force a coupled hydrodynamic ecosystem model (BIMS) for a hindcast simulation from 1980-2000. Model skill was assessed by model comparisons with SeaWiFS surface chlorophyll distributions. We study the regional differences the introduction of invasive comb jelly Mnemiopsis leidyi has on modeled ecosystem dynamics as well as the regional influence of changing river nutrient loads on ecosystem dynamics. We can demonstrate clearly that the appearance of M. Leidyi changes ecosystem functioning through exerting grazing pressure on zooplankton and thereby changing the seasonal cycle of phytoplankton and zooplankton species significantly. On the north-western shelf this effect is less pronounced than in the southeast Black Sea, where zooplankton is grazed down more heavily, allowing for higher phytoplankton biomass. In addition, the Black Sea ecosystem shows strong regional nitrate limitation, and high sensitivity to increased eutrophication: A 50% increase in nutrient loading causes a 48% increase in primary production in the eastern regions of the Black Sea, while the north-western shelf reacts more moderately. Despite an increase in primary production, chlorophyll-a concentrations typically respond weakly to changes in nitrate availability. This indicates that increased grazing closely mirrors an increase in productivity. This is confirmed by an increase in zooplankton biomass. It is important to note that for this reason simulated chlorophyll concentration is not a good indicator of eutrophication in the Black Sea. The reduction in the productivity of the entire Black Sea system associated with a reduction in riverine nutrient loadings is
Millennial-Scale ITCZ Variability in the Tropical Atlantic and Dynamics of Amazonian Rain Forest
Wang, X.; Auler, A. S.; Edwards, R. L.; Cheng, H.; Shen, C.; Smart, P. L.; Richards, D. A.
2003-12-01
Precipitation in the Amazon Basin is largely related to the intertropical convergence zone (ITCZ) in the tropical Atlantic which undergoes a regular seasonal migration. We chose a site south of the present day rainforest in semiarid northeastern Brazil, in order to study the timing of pluvial periods when the southern extend of the ITCZ would have been much further south than today. Shifts in the ITCZ position may have influenced the dynamics of rain forest and species diversity. We collected speleothems from northern Bahia state, located southeast of Amazonia. Age determinations with U-series dating methods show that samples grew rapidly during relatively short intervals (several hundreds of years) of glacial periods in the last 210 kyr. In addition, paleopluvial phases delineated by speleothem growth intervals show millennial-scale variations. Pluvial phases coincide with the timing of weak East Asian summer monsoon intensities (Wang et al., 2001, Science 294: 2345-2348), which have been correlated to the timing of stadials in Greenland ice core records and Heinrich events (Bond and Lotti, 1995, Science 267: 1005-1010). Furthermore, these intervals correspond to the periods of light color reflectance of Cariaco Basin sediments from ODP Hole 1002C (Peterson et al., 2000, Science, 290: 1947-1951), which was suggested to be caused by a southward shift of the northernmost position of the ITCZ and decreased rainfall in this region. Abrupt precipitation changes in northeastern Brazil may be due to the southward displacement of the southernmost position of the ITCZ associated with atmosphere-ocean circulation changes caused by (1) an increase in northern high latitude-tropical temperature gradient (Chiang et al., 2003, Paleoceanography, in press), and/or (2) the bipolar seesaw mechanism (Broecker et al., 1998, Paleoceanography 13: 119-121) during these Heinrich events. Pluvial phases are also coincident with higher insolation at 10° S during austral autumn. This
Romero, Estela; Peters, Francesc; Arin, Laura; Guillén, Jorge
2014-04-01
Contrary to what happens in open waters, where chlorophyll values and plankton dynamics can be predicted with a reasonable accuracy on an annual basis, biological parameters analyzed for coastal waters often show slight seasonality, and are exposed to numerous and convergent forcing factors that make it difficult to draw clear patterns. On top of this large natural variability, coastal locations subjected to urban sprawl suffer further human impact that may increase the unpredictability of plankton dynamics. Here we present the results of a multi-year time series of monthly samplings carried out in a coastal location by the city of Barcelona (NW Mediterranean) that is highly exposed to anthropogenic disturbances. Our data confirm the existence of complex patterns throughout the year. Freshwater inputs proved to be an important source of nutrients, yet the response of the planktonic organisms was vague and not systematic, contrary to the results of a previous study at a nearby coastal site less affected by human activities. The severity of anthropogenic disruptions was partially masked by the co-occurrence of natural physical phenomena, e.g., waste spills often come with downpours and large river discharge. In the NW Mediterranean, there seems to be a gradient of decreasing predictability on plankton dynamics from offshore to coastal waters with little human influence, where seasonality can be largely modified by local processes but the biological response is systematic and fairly predictable, and finally to urban coastal locations, where the seasonal background is diluted by numerous perturbations and there exists a variable pattern of biological responses. Our study underlines the importance of specific coastal processes in determining the structure and dynamics of the planktonic community, and the need to characterize coastal areas setting aside some of the assumptions valid for open ocean regions (e.g., (1) in the open ocean seasonality dominates annual nutrient
THE SEAFARERS’ HUMAN CAPITAL VARIABLES AND THE CREW PROFILE DYNAMIC ADJUSTMENT
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Catalin POPA
2016-06-01
Full Text Available The human capital is one of the most relevant functional dimensions of the maritime transportation business, considering the seaborne particularities in the crossing countries, cultures and heterogeneous environment as onboard the maritime vessels. The nowadays great competitiveness in this area of transportation services has encouraged many companies to pursue new ways to maintain a competitive advantage, valuing its human capital. Thus, in spite of the propensity for standardisation in field of human resources profile, the seafaring crews’ management is still facing lots of issues in operational tasks’ fulfilment onboard to maritime ships, due to individual misalignment within the collective framework of the on-board teams. As is presented in the article, the individual profile of a seafarer has to be precisely defined to be efficiently integrated in the crew, but not only in professional matters, but also into a comprehensive manner, in order to support a proper adjustment of the individual seafarer behaviour to the group profile requirement, onboard to maritime vessels. STCW provisions are very welcomed in establishing common standards for professional variable of the seafarers’ individual profile, but is still missing to approach the organizational dimensions, apart to the leadership skills or risk behaviour. As shown in the article below, for a recruitment agent and further, for the ship Master is important to find the suitable employee, not only in terms of professional knowledge, skills and abilities, but also in cultural or psycho-sociological individual dimensions, as to adjust the individual to the group profile, accordingly and effectively.
Dynamics of protein noise can distinguish between alternate sources of gene-expression variability.
Singh, Abhyudai; Razooky, Brandon S; Dar, Roy D; Weinberger, Leor S
2012-01-01
Within individual cells, two molecular processes have been implicated as sources of noise in gene expression: (i) Poisson fluctuations in mRNA abundance arising from random birth and death of individual mRNA transcripts or (ii) promoter fluctuations arising from stochastic promoter transitions between different transcriptional states. Steady-state measurements of variance in protein levels are insufficient to discriminate between these two mechanisms, and mRNA single-molecule fluorescence in situ hybridization (smFISH) is challenging when cellular mRNA concentrations are high. Here, we present a perturbation method that discriminates mRNA birth/death fluctuations from promoter fluctuations by measuring transient changes in protein variance and that can operate in the regime of high molecular numbers. Conceptually, the method exploits the fact that transcriptional blockage results in more rapid increases in protein variability when mRNA birth/death fluctuations dominate over promoter fluctuations. We experimentally demonstrate the utility of this perturbation approach in the HIV-1 model system. Our results support promoter fluctuations as the primary noise source in HIV-1 expression. This study illustrates a relatively simple method that complements mRNA smFISH hybridization and can be used with existing GFP-tagged libraries to include or exclude alternate sources of noise in gene expression.
Optimal Use Of Spatial Variability And Complex Dynamics In Hydrology: Are We There Yet?
Foufoula-Georgiou, Efi
Hydrologic Science has witnessed significant technological advances over the last decade: many more observations have become available from remote sensors and computer power has quadrupled. One would expect then, that advances in hydrologic understanding and prediction accuracy have been commensurate with these develop- ments. But is this really so? Have we used the information empowerment with the same ingenuity as our predecessors showed to compensate for lack of information? They advanced conceptual modeling, lumped parameterization and calibration tech- niques to improve predictions. Have we, in turn, advanced our methodologies enough to deal with detailed information of process variability, interaction of processes across scales, complexity, and uncertainties? And equally important, do we have adequate methodologies to judge the degree of our progress? Hydrologic Science is now at the forefront of Earth Sciences. There are pressing questions for the new generation to ad- dress and new approaches to learning from data, modeling and assessing predictability might be in order. This talk will address some of these issues.
Intrapopulation fixation index dynamics in finite populations with variable outcrossing rates
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Coelho Alexandre Siqueira Guedes
2003-01-01
Full Text Available The intrapopulation fixation index ( f is inversely related to the outcrossing rate (t. Results obtained from data on molecular markers of natural populations have shown that these values are highly variable, even when measured in the same group of individuals. It is thus suggested that factors besides those described in Wright's genetic equilibrium must be operating. Using simulated data sets this study shows that the finite size condition of a population is sufficient to spread the estimated f values along a range at equilibrium, as opposed to keeping them at the theoretical equilibrium point. The variation in outcrossing rates can amplify this range considerably. Correlation between estimated f values obtained from different loci in this condition showed to be negatively related to the outcrossing rates, and positively related to the variance of these rates along generations. The finite size of populations associated to small fluctuations in t mean values over time may explain the usually reported high variation among estimated f values of different loci.
Genetic variability and evolutionary dynamics of viruses of the family Closteroviridae
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Luis eRubio
2013-06-01
Full Text Available RNA viruses have a great potential for genetic variation, rapid evolution and adaptation. Characterization of the genetic variation of viral populations provides relevant information on the processes involved in virus evolution and epidemiology and it is crucial for designing reliable diagnostic tools and developing efficient and durable disease control strategies. Here we performed an updated analysis of sequences available in Genbank and reviewed present knowledge on the genetic variability and evolutionary processes of viruses of the family Closteroviridae. Several factors have shaped the genetic structure and diversity of closteroviruses. I A strong negative selection seems to be responsible for the high genetic stability in space and time for some viruses. II Long distance migration, probably by human transport of infected propagative plant material, have caused that genetically similar virus isolates are found in distant geographical regions. III Recombination between divergent sequence variants have generated new genotypes and plays an important role for the evolution of some viruses of the family Closteroviridae. IV Interaction between virus strains or between different viruses in mixed infections may alter accumulation of certain strains. V Host change or virus transmission by insect vectors induced changes in the viral population structure due to positive selection of sequence variants with higher fitness for host-virus or vector-virus interaction (adaptation or by genetic drift due to random selection of sequence variants during the population bottleneck associated to the transmission process.
Climate variability, human wildlife conflict and population dynamics of lions Panthera leo
Trinkel, Martina
2013-04-01
Large carnivores are threatened by habitat loss, declining prey populations and direct persecution. Pride dynamics of eight lion prides in the centre of the Etosha National Park, Namibia are described during a 16-year study. Since the beginning of the 1980s, the number of adult and subadult lions declined continuously to two third of its initial population size, and reached a new equilibrium in the 1990s. Pride sizes decreased from 6.3 adult females in 1989 to 2.8 lionesses in 1997. While the number of adult females declined continuously, the number of adult males, subadult females and subadult males remained constant over the years. A severe drought period, lasting for more than 20 years, led to declining prey populations inside the lions' territory. Besides declining prey populations, conflict with humans at the border of Etosha puts substantial pressure onto the lion population: 82 % of all known lion mortalities were caused by humans, and most of these consisted of adult females (28 %) and subadult males (29 %). I postulate that the considerable decline in the lion population is a response to declining prey populations, and although the human predator conflict is severe, it does not seem to limit the size of Etosha's lion population.
Altieri, Nicholas; Wenger, Michael J
2013-01-01
Speech perception engages both auditory and visual modalities. Limitations of traditional accuracy-only approaches in the investigation of audiovisual speech perception have motivated the use of new methodologies. In an audiovisual speech identification task, we utilized capacity (Townsend and Nozawa, 1995), a dynamic measure of efficiency, to quantify audiovisual integration. Capacity was used to compare RT distributions from audiovisual trials to RT distributions from auditory-only and visual-only trials across three listening conditions: clear auditory signal, S/N ratio of -12 dB, and S/N ratio of -18 dB. The purpose was to obtain EEG recordings in conjunction with capacity to investigate how a late ERP co-varies with integration efficiency. Results showed efficient audiovisual integration for low auditory S/N ratios, but inefficient audiovisual integration when the auditory signal was clear. The ERP analyses showed evidence for greater audiovisual amplitude compared to the unisensory signals for lower auditory S/N ratios (higher capacity/efficiency) compared to the high S/N ratio (low capacity/inefficient integration). The data are consistent with an interactive framework of integration, where auditory recognition is influenced by speech-reading as a function of signal clarity.
Directory of Open Access Journals (Sweden)
Nicholas eAltieri
2013-09-01
Full Text Available Speech perception engages both auditory and visual modalities. Limitations of traditional accuracy-only approaches in the investigation of audiovisual speech perception have motivated the use of new methodologies. In an audiovisual speech identification task, we utilized capacity (Townsend & Nozawa, 1995, a dynamic measure of efficiency, to quantify audiovisual integration. Capacity was used to compare RT distributions from audiovisual trials to RT distributions from auditory-only and visual-only trials across three listening conditions: clear auditory signal, S/N ratio of -12 dB, and S/N ratio of -18 dB. The purpose was to obtain EEG recordings in conjunction with capacity to investigate how a late ERP co-varies with integration efficiency. Results showed efficient audiovisual integration for low auditory S/N ratios, but inefficient audiovisual integration when the auditory signal was clear. The ERP analyses showed evidence for greater audiovisual amplitude in lower auditory S/N ratios (higher capacity/efficiency compared to the high S/N ratio (low capacity/inefficient integration. The data are consistent with an interactive framework of integration, where auditory recognition is influenced by speech-reading as a function of signal clarity.
Rosenzweig, Ravid; Furman, Alex; Dosoretz, Carlos; Shavit, Uri
2014-07-01
Biofilm effects on water flow in unsaturated environments have largely been ignored in the past. However, intensive engineered systems that involve elevated organic loads such as wastewater irrigation, effluent recharge, and bioremediation processes make understanding how biofilms affect flow highly important. In the current work, we present a channel-network model that incorporates water flow, substrate transport, and biofilm dynamics to simulate the alteration of soil hydraulic properties, namely water retention and conductivity. The change in hydraulic properties due to biofilm growth is not trivial and depends highly on the spatial distribution of the biofilm development. Our results indicate that the substrate mass transfer coefficient across the water-biofilm interface dominates the spatiotemporal distribution of biofilm. High mass transfer coefficients lead to uncontrolled biofilm growth close to the substrate source, resulting in preferential clogging of the soil. Low mass transfer coefficients, on the other hand, lead to a more uniform biofilm distribution. The first scenario leads to a dramatic reduction of the hydraulic conductivity with almost no change in water retention, whereas the second scenario has a smaller effect on conductivity but a larger influence on retention. The current modeling approach identifies key factors that still need to be studied and opens the way for simulation and optimization of processes involving significant biological activity in unsaturated soils.
Geophysical Investigations at Hidden Dam, Raymond, California Flow Simulations
Minsley, Burke J.; Ikard, Scott
2010-01-01
Numerical flow modeling and analysis of observation-well data at Hidden Dam are carried out to supplement recent geophysical field investigations at the site (Minsley and others, 2010). This work also is complementary to earlier seepage-related studies at Hidden Dam documented by Cedergren (1980a, b). Known seepage areas on the northwest right abutment area of the downstream side of the dam was documented by Cedergren (1980a, b). Subsequent to the 1980 seepage study, a drainage blanket with a sub-drain system was installed to mitigate downstream seepage. Flow net analysis provided by Cedergren (1980a, b) suggests that the primary seepage mechanism involves flow through the dam foundation due to normal reservoir pool elevations, which results in upflow that intersects the ground surface in several areas on the downstream side of the dam. In addition to the reservoir pool elevations and downstream surface topography, flow is also controlled by the existing foundation geology as well as the presence or absence of a horizontal drain in the downstream portion of the dam. The current modeling study is aimed at quantifying how variability in dam and foundation hydrologic properties influences seepage as a function of reservoir stage. Flow modeling is implemented using the COMSOL Multiphysics software package, which solves the partially saturated flow equations in a two-dimensional (2D) cross-section of Hidden Dam that also incorporates true downstream topography. Use of the COMSOL software package provides a more quantitative approach than the flow net analysis by Cedergren (1980a, b), and allows for rapid evaluation of the influence of various parameters such as reservoir level, dam structure and geometry, and hydrogeologic properties of the dam and foundation materials. Historical observation-well data are used to help validate the flow simulations by comparing observed and predicted water levels for a range of reservoir elevations. The flow models are guided by, and
Hidden geometry of traffic jamming
Andjelković, Miroslav; Gupte, Neelima; Tadić, Bosiljka
2015-05-01
We introduce an approach based on algebraic topological methods that allow an accurate characterization of jamming in dynamical systems with queues. As a prototype system, we analyze the traffic of information packets with navigation and queuing at nodes on a network substrate in distinct dynamical regimes. A temporal sequence of traffic density fluctuations is mapped onto a mathematical graph in which each vertex denotes one dynamical state of the system. The coupling complexity between these states is revealed by classifying agglomerates of high-dimensional cliques that are intermingled at different topological levels and quantified by a set of geometrical and entropy measures. The free-flow, jamming, and congested traffic regimes result in graphs of different structure, while the largest geometrical complexity and minimum entropy mark the edge of the jamming region.
Energy Technology Data Exchange (ETDEWEB)
Ruiz-Navarro, A.; Barbera, G. G.; Albaladejo, J.
2009-07-01
Arid and semi-arid Mediterranean soils are particularly sensitive to degradation processes, and soil fertility could play important role in restoration/conservation practices. Our objective was to study the relationships between soil and landscape at different scales in order to understand the main drivers of soil fertility on a semiarid catchment. A stratified sampling plan was carried out to take soil and landscape representative variability. Multivariate statistic techniques were used to elucidate the relationship between both. The results showed that soil fertility are positively related with density of vegetation and topographical conditions favourable to soil moisture at small scale, while negatively with topographical factors that contributed erosion dynamic on ero debility lithologies at medium and large scale. (Author) 8 refs.
Li, Liang
2016-01-01
In coherent detection employing digital signal processing, chromatic dispersion (CD) can be compensated effectively in the electrical domain. In practical optical transport networks, the signal lightpaths between two terminal nodes can be different due to current network conditions. Accordingly, the transmission distance and the accumulated dispersion in the lightpath cannot be predicted. Therefore, the adaptive compensation of dynamic dispersion such as the use of least-mean-square (LMS) algorithm is necessary in such optical fiber networks to enable a flexible routing and switching. In this paper, we present a detailed analysis on the adaptive dispersion compensation using the LMS algorithms in coherent optical transmission networks. Numerical simulations have been carried out accordingly. It can be found that the variable-step-size LMS equalizer can achieve the adaptive CD equalization with a lower complexity, compared to the traditional LMS algorithm.
Hidden simplicity of gauge theory amplitudes
Energy Technology Data Exchange (ETDEWEB)
Drummond, J M, E-mail: drummond@lapp.in2p3.f [LAPTH, Universite de Savoie, CNRS, B.P. 110, F-74941 Annecy-le-Vieux, Cedex (France)
2010-11-07
These notes were given as lectures at the CERN Winter School on Supergravity, Strings and Gauge Theory 2010. We describe the structure of scattering amplitudes in gauge theories, focussing on the maximally supersymmetric theory to highlight the hidden symmetries which appear. Using the Britto, Cachzo, Feng and Witten (BCFW) recursion relations we solve the tree-level S-matrix in N=4 super Yang-Mills theory and describe how it produces a sum of invariants of a large symmetry algebra. We review amplitudes in the planar theory beyond tree level, describing the connection between amplitudes and Wilson loops, and discuss the implications of the hidden symmetries.
Hidden simplicity of gauge theory amplitudes
Drummond, J. M.
2010-11-01
These notes were given as lectures at the CERN Winter School on Supergravity, Strings and Gauge Theory 2010. We describe the structure of scattering amplitudes in gauge theories, focussing on the maximally supersymmetric theory to highlight the hidden symmetries which appear. Using the Britto, Cachzo, Feng and Witten (BCFW) recursion relations we solve the tree-level S-matrix in \\ {N}=4 super Yang-Mills theory and describe how it produces a sum of invariants of a large symmetry algebra. We review amplitudes in the planar theory beyond tree level, describing the connection between amplitudes and Wilson loops, and discuss the implications of the hidden symmetries.
Hidden neural networks: application to speech recognition
DEFF Research Database (Denmark)
Riis, Søren Kamaric
1998-01-01
We evaluate the hidden neural network HMM/NN hybrid on two speech recognition benchmark tasks; (1) task independent isolated word recognition on the Phonebook database, and (2) recognition of broad phoneme classes in continuous speech from the TIMIT database. It is shown how hidden neural networks...... (HNNs) with much fewer parameters than conventional HMMs and other hybrids can obtain comparable performance, and for the broad class task it is illustrated how the HNN can be applied as a purely transition based system, where acoustic context dependent transition probabilities are estimated by neural...
Dark Radiation from a hidden U(1)
Vogel, Hendrik
2015-01-01
We discuss the impact of a hidden sector consisting of Minicharged Particles (MCPs) and massless hidden photons on the expansion history of our Universe. We present parameter scans for the amount of extra relativistic particles (Neff) and the abundance of light nuclei for fermionic MCPs with masses between ~100 keV and 10 GeV and minicharges in the range 10^(-11)-1. Current CMB and BBN data significantly constrain the available parameter space of MCPs. The shown results are a valuable indicator for future experimental searches and are presented in a flexible way so that more accurate results on Neff can be easily interpreted.
Hidden Symmetries, Central Charges and All That
de Wit, Bernard; Wit, Bernard de; Nicolai, Hermann
2001-01-01
In this review we discuss hidden symmetries of toroidal compactifications of eleven-dimensional supergravity. We recall alternative versions of this theory which exhibit traces of the hidden symmetries when still retaining the massive Kaluza-Klein states. We reconsider them in the broader perspective of M-theory which incorporates a more extended variety of BPS states. We also argue for a new geometry that may underly these theories. All our arguments point towards an extension of the number of space-time coordinates beyond eleven.
Hidden Subgroup States are Almost Orthogonal
Ettinger, M; Knill, E H; Ettinger, Mark; Hoyer, Peter; Knill, Emanuel
1999-01-01
It is well known that quantum computers can efficiently find a hidden subgroup $H$ of a finite Abelian group $G$. This implies that after only a polynomial (in $\\log |G|$) number of calls to the oracle function, the states corresponding to different candidate subgroups have exponentially small inner product. We show that this is true for noncommutative groups also. We present a quantum algorithm which identifies a hidden subgroup of an arbitrary finite group $G$ in only a linear (in $\\log |G|$) number of calls to the oracle function. This is exponentially better than the best classical algorithm. However our quantum algorithm requires an exponential amount of time, as in the classical case.
DISCOVERY 2010: Spatial and temporal variability in a dynamic polar ecosystem
Tarling, G. A.; Ward, P.; Atkinson, A.; Collins, M. A.; Murphy, E. J.
2012-01-01
DIC deficits, the South Georgia bloom was found to contain the strongest seasonal carbon uptake in the ice-free zone of the Southern Ocean. The surveys also encountered low-production, iron-limited regions, a situation more typical of the wider Southern Ocean. The response of primary and secondary consumers to spatial and temporal heterogeneity in production was complex. Many of the life-cycles of small pelagic organisms showed a close coupling to the seasonal cycle of food availability. For instance, Antarctic krill showed a dependence on early, non-ice-associated blooms to facilitate early reproduction. Strategies to buffer against environmental variability were also examined, such as the prevalence of multiyear life-cycles and variability in energy storage levels. Such traits were seen to influence the way in which Scotia Sea communities were structured, with biomass levels in the larger size classes being higher than in other ocean regions. Seasonal development also altered trophic function, with the trophic level of higher predators increasing through the course of the year as additional predator-prey interactions emerged in the lower trophic levels. Finally, our studies re-emphasised the role that the simple phytoplankton-krill-higher predator food chain plays in this Southern Ocean region, particularly south of the SACCF. To the north, alternative food chains, such as those involving copepods, macrozooplankton and mesopelagic fish, were increasingly important. Continued ocean warming in this region is likely to increase the prevalence of such alternative such food chains with Antarctic krill predicted to move southwards.
Dynamic of Mutational Events in Variable Number Tandem Repeats of Escherichia coli O157:H7
Directory of Open Access Journals (Sweden)
A. V. Bustamante
2013-01-01
Full Text Available VNTRs regions have been successfully used for bacterial subtyping; however, the hypervariability in VNTR loci is problematic when trying to predict the relationships among isolates. Since few studies have examined the mutation rate of these markers, our aim was to estimate mutation rates of VNTRs specific for verotoxigenic E. coli O157:H7. The knowledge of VNTR mutational rates and the factors affecting them would make MLVA more effective for epidemiological or microbial forensic investigations. For this purpose, we analyzed nine loci performing parallel, serial passage experiments (PSPEs on 9 O157:H7 strains. The combined 9 PSPE population rates for the 8 mutating loci ranged from 4.4 × 10−05 to 1.8 × 10−03 mutations/generation, and the combined 8-loci mutation rate was of 2.5 × 10−03 mutations/generation. Mutations involved complete repeat units, with only one point mutation detected. A similar proportion between single and multiple repeat changes was detected. Of the 56 repeat mutations, 59% were insertions and 41% were deletions, and 72% of the mutation events corresponded to O157-10 locus. For alleles with up to 13 UR, a constant and low mutation rate was observed; meanwhile longer alleles were associated with higher and variable mutation rates. Our results are useful to interpret data from microevolution and population epidemiology studies and particularly point out that the inclusion or not of O157-10 locus or, alternatively, a differential weighting data according to the mutation rates of loci must be evaluated in relation with the objectives of the proposed study.
Hippotherapy acute impact on heart rate variability non-linear dynamics in neurological disorders.
Cabiddu, Ramona; Borghi-Silva, Audrey; Trimer, Renata; Trimer, Vitor; Ricci, Paula Angélica; Italiano Monteiro, Clara; Camargo Magalhães Maniglia, Marcela; Silva Pereira, Ana Maria; Rodrigues das Chagas, Gustavo; Carvalho, Eliane Maria
2016-05-15
Neurological disorders are associated with autonomic dysfunction. Hippotherapy (HT) is a therapy treatment strategy that utilizes a horse in an interdisciplinary approach for the physical and mental rehabilitation of people with physical, mental and/or psychological disabilities. However, no studies have been carried out which evaluated the effects of HT on the autonomic control in these patients. Therefore, the objective of the present study was to investigate the effects of a single HT session on cardiovascular autonomic control by time domain and non-linear analysis of heart rate variability (HRV). The HRV signal was recorded continuously in twelve children affected by neurological disorders during a HT session, consisting in a 10-minute sitting position rest (P1), a 15-minute preparatory phase sitting on the horse (P2), a 15-minute HT session (P3) and a final 10-minute sitting position recovery (P4). Time domain and non-linear HRV indices, including Sample Entropy (SampEn), Lempel-Ziv Complexity (LZC) and Detrended Fluctuation Analysis (DFA), were calculated for each treatment phase. We observed that SampEn increased during P3 (SampEn=0.56±0.10) with respect to P1 (SampEn=0.40±0.14, p<0.05), while DFA decreased during P3 (DFA=1.10±0.10) with respect to P1 (DFA=1.26±0.14, p<0.05). A significant SDRR increase (p<0.05) was observed during the recovery period P4 (SDRR=50±30ms) with respect to the HT session period P3 (SDRR=30±10ms). Our results suggest that HT might benefit children with disabilities attributable to neurological disorders by eliciting an acute autonomic response during the therapy and during the recovery period.
Ishikawa, Hiroshi; Chen, Chieh-Li; Wollstein, Gadi; Grimm, Jonathan L.; Ling, Yun; Bilonick, Richard A.; Sigal, Ian A.; Kagemann, Larry; Schuman, Joel S.
2013-01-01
Purpose. To develop and test a novel signal enhancement method for optical coherence tomography (OCT) images based on the high dynamic range (HDR) imaging concept. Methods. Three virtual channels, which represent low, medium, and high signal components, were produced for each OCT signal dataset. The dynamic range of each signal component was normalized to the full gray scale range. Finally, the three components were recombined into one image using various weights. Fourteen eyes of 14 healthy volunteers were scanned multiple times using time-domain (TD)-OCT before and while preventing blinking in order to produce a wide variety of signal strength (SS) images on the same eye scanned on the same day. For each eye, a pair of scans with the highest and lowest SS with successful retinal nerve fiber layer (RNFL) segmentation was selected to test the signal enhancement effect. In addition, spectral-domain (SD)-OCT images with poor signal qualities were also processed. Results. Mean SS of good and poor quality scans were 9.0 ± 1.1 and 4.4 ± 0.9, respectively. TD-OCT RNFL thickness showed significant differences between good and poor quality scans on the same eye (mean difference 11.9 ± 6.0 μm, P < 0.0001, paired t-test), while there was no significant difference after signal enhancement (1.7 ± 6.2 μm, P = 0.33). However, HDR had weaker RNFL compensation effect on images with SS less than or equal to 4, while it maintained good compensation effect on images with SS greater than 4. Successful signal enhancement was also confirmed subjectively on SD-OCT images. Conclusion. The HDR imaging successfully restored OCT signal and image quality and reduced RNFL thickness differences due to variable signal level to the level within the expected measurement variability. This technique can be applied to both TD- and SD-OCT images. PMID:23299477
Evaluation of the variable depth resolution of active dynamic thermography on human skin
Prindeze, Nicholas J.; Hoffman, Hilary A.; Carney, Bonnie C.; Moffatt, Lauren T.; Loew, Murray H.; Shupp, Jeffrey W.
2015-06-01
Active dynamic thermography (ADT) is an imaging technique capable of characterizing the non-homogenous thermal conductance of damaged tissues. The purpose of this study was to determine optimal stimulation parameters and quantify the optical resolution of ADT through various depths of human skin. Excised tissue from plastic surgery operations was collected immediately following excision. A total of 12 thin to thick split-thickness grafts were harvested from 3 patients. Grafts were placed on top of a 3D printed resolution chart and thermal stimulation was applied from a 300W halogen lamp array for between 0.5-10 seconds to determine optimal parameters. Video was captured with a thermal camera, and analysis was performed by reconstructing an image from thermal gradients. In this study ADT resolved 0.445+/-0 lp/mm at a depth of 0.010", 0.356+/-0.048 lp/mm at a depth of 0.015", 0.334+/-0.027 lp/mm at a depth of 0.020" and 0.265+/-0.022 lp/mm at a depth of 0.025". The stimulus energy required for maximum resolution at each depth was 3- 4s, 8s, 12s and 12s respectively. ADT is a sensitive technique for imaging dermal structure, capable of resolving detail as fine as 1124 μm, 1427 μm, 1502 μm and 1893 μm in thin to thick split-thickness skin grafts respectively. This study has characterized a correlation between stimulus input and maximal resolution at differing depths of skin. It has also defined the functional imaging depth of ADT to below the sub-cutis, well below conventional spectrophotometric techniques.
Non-Linear Dynamics of Macroeconomic Variables: The Case of Greece
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Sophia Kassapi
2015-06-01
Full Text Available This paper is part of an ongoing doctoral dissertation. It examines the long run relationship between government spending on education, GDP growth and educational enrollments in all levels, for Greece in the years 1960-2012, leveling up to capture more complex dependent dynamics in time series. OECD Indicator A11 shows that, life satisfaction, civic engagement and health. are at the same level for adults with tertiary education and adults with upper secondary education for Greece. Having conducted Linear Granger tests, this study goes beyond, following the methodology of both non-parametric testing for asymptotic Granger causality in C, and non-parametric bootstrapped bidirectional Granger causality, an MS Dos application in C. We apply a new nonparametric test for Granger non-causality by Diks and Panchenko (2005, 2006 as well as the conventional linear Granger test on the time series. The secondary data used in this present study, have been processed through MATLAB interpolation function. There is a strong symmetric nonlinear causal relationship detected between government spending on education and enrollments in higher education, and vice versa, .An even stronger, both symmetric and asymmetric nonlinear relationship between higher education enrollments and Gdp growth is validated confirming a spectacular case of “adverse causality”. Government spending in education is causally related with Gdp growth in a symmetric as much as an asymmetric nonlinear relationship. Also, lagged values of secondary enrollments are a major predictor of Gdp growth. Keywords: Economic growth, Greek economy, Granger Causality, Non-linearity.
Searching for hidden sectors in multiparticle production at the LHC
Sanchis-Lozano, Miguel-Angel; Moreno-Picot, Salvador
2015-01-01
We study the impact of a hidden sector beyond the Standard Model, e.g. a Hidden Valley model, on factorial moments and cumulants of multiplicity distributions in multiparticle production with a special emphasis on the prospects for LHC results.
Entropy Rate for Hidden Markov Chains with rare transitions
2010-01-01
We consider Hidden Markov Chains obtained by passing a Markov Chain with rare transitions through a noisy memoryless channel. We obtain asymptotic estimates for the entropy of the resulting Hidden Markov Chain as the transition rate is reduced to zero.