53 research outputs found
Symbolic transfer entropy rate is equal to transfer entropy rate for bivariate finite-alphabet stationary ergodic Markov processes
Transfer entropy is a measure of the magnitude and the direction of
information flow between jointly distributed stochastic processes. In recent
years, its permutation analogues are considered in the literature to estimate
the transfer entropy by counting the number of occurrences of orderings of
values, not the values themselves. It has been suggested that the method of
permutation is easy to implement, computationally low cost and robust to noise
when applying to real world time series data. In this paper, we initiate a
theoretical treatment of the corresponding rates. In particular, we consider
the transfer entropy rate and its permutation analogue, the symbolic transfer
entropy rate, and show that they are equal for any bivariate finite-alphabet
stationary ergodic Markov process. This result is an illustration of the
duality method introduced in [T. Haruna and K. Nakajima, Physica D 240, 1370
(2011)]. We also discuss the relationship among the transfer entropy rate, the
time-delayed mutual information rate and their permutation analogues.Comment: 18 page
Symbolic local information transfer
Recently, the permutation-information theoretic approach has been used in a
broad range of research fields. In particular, in the study of highdimensional
dynamical systems, it has been shown that this approach can be effective in
characterizing global properties, including the complexity of their
spatiotemporal dynamics. Here, we show that this approach can also be applied
to reveal local spatiotemporal profiles of distributed computations existing at
each spatiotemporal point in the system. J. T. Lizier et al. have recently
introduced the concept of local information dynamics, which consists of
information storage, transfer, and modification. This concept has been
intensively studied with regard to cellular automata, and has provided
quantitative evidence of several characteristic behaviors observed in the
system. In this paper, by focusing on the local information transfer, we
demonstrate that the application of the permutation-information theoretic
approach, which introduces natural symbolization methods, makes the concept
easily extendible to systems that have continuous states. We propose measures
called symbolic local transfer entropies, and apply these measures to two test
models, the coupled map lattice (CML) system and the Bak-Sneppen model
(BS-model), to show their relevance to spatiotemporal systems that have
continuous states.Comment: 20 pages, 7 figure
Symbolic local information transfer
Recently, the permutation-information theoretic approach has been used in a broad range of research fields. In particular, in the study of high-dimensional dynamical systems, it has been shown that this approach can be effective in characterizing global properties, including the complexity of their spatiotemporal dynamics. Here, we show that this approach can also be applied to reveal local spatiotemporal profiles of distributed computations existing at each spatiotemporal point in the system. J. T. Lizier et al. have recently introduced the concept of local information dynamics, which consists of information storage, transfer, and modification. This concept has been intensively studied with regard to cellular automata, and has provided quantitative evidence of several characteristic behaviors observed in the system. In this paper, by focusing on the local information transfer, we demonstrate that the application of the permutation-information theoretic approach, which introduces natural symbolization methods, makes the concept easily extendible to systems that have continuous states. We propose measures called symbolic local transfer entropies, and apply these measures to two test models, the coupled map lattice (CML) system and the Bak-Sneppen model (BS-model), to show their relevance to spatiotemporal systems that have continuous states. In the CML, we demonstrate that it can be successfully used as a spatiotemporal filter to stress a coherent structure buried in the system. In particular, we show that the approach can clearly stress out defect turbulences or Brownian motion of defects from the background, which gives quantitative evidence suggesting that these moving patterns are the information transfer substrate in the spatiotemporal system. We then show that these measures reveal qualitatively different properties from the conventional approach using the sliding window method, and are also robust against external noise. In the BS-model, we demonstrate that these measures can provide novel insight to the model, featuring how symbolic local information transfer is related to the dynamical properties of the elements involved in a spatiotemporal dynamic
Permutation Complexity and Coupling Measures in Hidden Markov Models
In [Haruna, T. and Nakajima, K., 2011. Physica D 240, 1370-1377], the authors
introduced the duality between values (words) and orderings (permutations) as a
basis to discuss the relationship between information theoretic measures for
finite-alphabet stationary stochastic processes and their permutation
analogues. It has been used to give a simple proof of the equality between the
entropy rate and the permutation entropy rate for any finite-alphabet
stationary stochastic process and show some results on the excess entropy and
the transfer entropy for finite-alphabet stationary ergodic Markov processes.
In this paper, we extend our previous results to hidden Markov models and show
the equalities between various information theoretic complexity and coupling
measures and their permutation analogues. In particular, we show the following
two results within the realm of hidden Markov models with ergodic internal
processes: the two permutation analogues of the transfer entropy, the symbolic
transfer entropy and the transfer entropy on rank vectors, are both equivalent
to the transfer entropy if they are considered as the rates, and the directed
information theory can be captured by the permutation entropy approach.Comment: 26 page
Permutation Complexity via Duality between Values and Orderings
We study the permutation complexity of finite-state stationary stochastic
processes based on a duality between values and orderings between values.
First, we establish a duality between the set of all words of a fixed length
and the set of all permutations of the same length. Second, on this basis, we
give an elementary alternative proof of the equality between the permutation
entropy rate and the entropy rate for a finite-state stationary stochastic
processes first proved in [Amigo, J.M., Kennel, M. B., Kocarev, L., 2005.
Physica D 210, 77-95]. Third, we show that further information on the
relationship between the structure of values and the structure of orderings for
finite-state stationary stochastic processes beyond the entropy rate can be
obtained from the established duality. In particular, we prove that the
permutation excess entropy is equal to the excess entropy, which is a measure
of global correlation present in a stationary stochastic process, for
finite-state stationary ergodic Markov processes.Comment: 26 page
Oral pathobiont induces systemic inflammation and metabolic changes associated with alteration of gut microbiota.
Periodontitis has been implicated as a risk factor for metabolic disorders such as type 2 diabetes, atherosclerotic vascular diseases, and non-alcoholic fatty liver disease. Although bacteremias from dental plaque and/or elevated circulating inflammatory cytokines emanating from the inflamed gingiva are suspected mechanisms linking periodontitis and these diseases, direct evidence is lacking. We hypothesize that disturbances of the gut microbiota by swallowed bacteria induce a metabolic endotoxemia leading metabolic disorders. To investigate this hypothesis, changes in the gut microbiota, insulin and glucose intolerance, and levels of tissue inflammation were analysed in mice after oral administration of Porphyromonas gingivalis, a representative periodontopathogens. Pyrosequencing revealed that the population belonging to Bacteroidales was significantly elevated in P. gingivalis-administered mice which coincided with increases in insulin resistance and systemic inflammation. In P. gingivalis-administered mice blood endotoxin levels tended to be higher, whereas gene expression of tight junction proteins in the ileum was significantly decreased. These results provide a new paradigm for the interrelationship between periodontitis and systemic diseases
Trion confinement in monolayer MoSe2 by carbon nanotube local gating
We have successfully confined trions into a one-dimensional restricted space
of a MoSe2 device with CNT gate electrodes. The dry transfer process, including
deterministic dry transfer of aligned CNTs, has led to an hBN-encapsulated
MoSe2 device with CNT back gate electrodes. In contrast to a location without
CNT gate electrodes, applying voltage via CNT gate electrodes significantly
alters PL spectra at a location with CNT gate electrodes. PL imaging has
revealed that image contrast from trions is linear along the CNT electrode
underneath, consistent with 1D confinement of trions in response to the CNT
local gating. The confinement width obtained from the PL image is 5.5 x 10^2
nm, consistent with nanoscale 1D confined trions with the diffraction limit
broadening. This work has demonstrated electrical control of excitonic states
at the nanoscale, leading to novel optoelectronic properties and exciton
devices in the future
Non-uniform distribution of the contraction/extension (CâE) in the left ventricular myocardium related to the myocardial function
AbstractObjectiveWe attempted to disclose the microscopic characteristics of the non-uniform distribution of the contraction and extension (CâE) of the left ventricular (LV) myocardium using a new methodology (echo-dynamography).MethodsThe distributions of the âaxial strain rateâ (aSR) and the intra-mural velocity in the local areas of the free wall including the posterior wall (PW) and interventricular septum (IVS) were microscopically obtained using echo-dynamography with a high accuracy of 821ÎŒm in the spatial resolution. The results were shown by the color M-mode echocardiogram or curvilinear graph. Subjects were 10 presumably normal volunteers.Results(1)Both the CâE in the pulsating LV wall showed non-uniformity spatially and time-sequentially.(2)The CâE property was better evaluated by the aSR distribution method rather than the intra-mural velocity distribution method.(3)Two types of non-uniformity of the aSR distribution were observed: i.e. (i) the difference of its (+)SR (contraction: C) or (â)SR (extension: E) was solely the âmagnitudeâ; (ii) the coexistence of both the (+) SR and (â)SR at the same time.(4)The aSR distribution during systole was either âspotted,â or âmulti-layered,â or âtonedâ distribution, whereas âstratified,â âtoned,â or âalternatingâ distributions were observed during diastole.(5)The aSR distribution in the longitudinal section plane was varied in the individual areas of the wall even during the same timing.(6)To the mechanical function of the LV, there was a different behavior between the IVS and PW.ConclusionsThe aSR and its distribution were the major determinants of the CâE property of the LV myocardium. Spatial as well as time-sequential uniformity of either contraction or extension did not exist. The myocardial function changed depending on the assemblage of the aSR distribution, and by the synergistic effect of (+)SR and (â)SR, the non-uniformity itself potentially served to hold the smooth LV mechanical function
On-site underground background measurements for the KASKA reactor-neutrino experiment
On-site underground background measurements were performed for the planned
reactor-neutrino oscillation experiment KASKA at Kashiwazaki-Kariwa nuclear
power station in Niigata, Japan. A small-diameter boring hole was excavated
down to 70m underground level, and a detector unit for -ray and
cosmic-muon measurements was placed at various depths to take data. The data
were analyzed to obtain abundance of natural radioactive elements in the
surrounding soil and rates of cosmic muons that penetrate the overburden. The
results will be reflected in the design of the KASKA experiment.Comment: 9 pages, 7 figures, final version for publication. Table 1 and Fig.5
have change
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