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Transfer entropy

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https://www.readbyqxmd.com/read/28539247/horizontal-visibility-graph-transfer-entropy-hvg-te-a-novel-metric-to-characterize-directed-connectivity-in-large-scale-brain-networks
#1
Meichen Yu, Arjan Hillebrand, Alida A Gouw, Cornelis J Stam
We propose a new measure, horizontal visibility graph transfer entropy (HVG-TE), to estimate the direction of information flow between pairs of time series. HVG-TE quantifies the transfer entropy between the degree sequences of horizontal visibility graphs derived from original time series. Twenty-one Rössler attractors unidirectionally coupled in the posterior-to-anterior direction were used to simulate 21-channel Electroencephalography (EEG) brain networks and validate the performance of the HVG-TE. We showed that the HVG-TE is robust to different levels of coupling strengths between the coupled Rössler attractors, a wide range of time delays, different sample sizes, the effects of noise and linear mixing, and the choice of reference for EEG data...
May 21, 2017: NeuroImage
https://www.readbyqxmd.com/read/28529761/developing-and-evaluating-a-mobile-driver-fatigue-detection-network-based-on-electroencephalograph-signals
#2
Jinghai Yin, Jianfeng Hu, Zhendong Mu
The rapid development of driver fatigue detection technology indicates important significance of traffic safety. The authors' main goals of this Letter are principally three: (i) A middleware architecture, defined as process unit (PU), which can communicate with personal electroencephalography (EEG) node (PEN) and cloud server (CS). The PU receives EEG signals from PEN, recognises the fatigue state of the driver, and transfer this information to CS. The CS sends notification messages to the surrounding vehicles...
February 2017: Healthcare Technology Letters
https://www.readbyqxmd.com/read/28523598/study-on-the-interaction-of-chromate-with-bovine-serum-albumin-by-spectroscopic-method
#3
Hongguang Cao, Yanli Yi
The interaction between two chromates [sodium chromate (Na2CrO4) and potassium chromate K2CrO4)] and bovine serum albumin (BSA) in physiological buffer (pH 7.4) was investigated by the fluorescence quenching technique. The results of fluorescence titration revealed that two chromates could strongly quench the intrinsic fluorescence of BSA through a static quenching procedure. The apparent binding constants K and number of binding sites n of chromate with BSA were obtained by the fluorescence quenching method...
May 18, 2017: Biometals: An International Journal on the Role of Metal Ions in Biology, Biochemistry, and Medicine
https://www.readbyqxmd.com/read/28507235/assessing-the-strength-of-cardiac-and-sympathetic-baroreflex-controls-via-transfer-entropy-during-orthostatic-challenge
#4
Alberto Porta, Andrea Marchi, Vlasta Bari, Beatrice De Maria, Murray Esler, Elisabeth Lambert, Mathias Baumert
The study assesses the strength of the causal relation along baroreflex (BR) in humans during an incremental postural challenge soliciting the BR. Both cardiac BR (cBR) and sympathetic BR (sBR) were characterized via BR sequence approaches from spontaneous fluctuations of heart period (HP), systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and muscle sympathetic nerve activity (MSNA). A model-based transfer entropy method was applied to quantify the strength of the coupling from SAP to HP and from DAP to MSNA...
June 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28505709/causal-influence-in-linear-langevin-networks-without-feedback
#5
Andrea Auconi, Andrea Giansanti, Edda Klipp
The intuition of causation is so fundamental that almost every research study in life sciences refers to this concept. However, a widely accepted formal definition of causal influence between observables is still missing. In the framework of linear Langevin networks without feedback (linear response models) we propose a measure of causal influence based on a new decomposition of information flows over time. We discuss its main properties and we compare it with other information measures like the transfer entropy...
April 2017: Physical Review. E
https://www.readbyqxmd.com/read/28504948/substructural-regularization-with-data-sensitive-granularity-for-sequence-transfer-learning
#6
Shichang Sun, Hongbo Liu, Jiana Meng, C L Philip Chen, Yu Yang
Sequence transfer learning is of interest in both academia and industry with the emergence of numerous new text domains from Twitter and other social media tools. In this paper, we put forward the data-sensitive granularity for transfer learning, and then, a novel substructural regularization transfer learning model (STLM) is proposed to preserve target domain features at substructural granularity in the light of the condition of labeled data set size. Our model is underpinned by hidden Markov model and regularization theory, where the substructural representation can be integrated as a penalty after measuring the dissimilarity of substructures between target domain and STLM with relative entropy...
May 12, 2017: IEEE Transactions on Neural Networks and Learning Systems
https://www.readbyqxmd.com/read/28470287/a-theoretical-study-on-hot-charge-transfer-states-and-dimensional-effects-of-organic-photocells-based-on-an-ideal-diode-model
#7
Tomomi Shimazaki, Takahito Nakajima
This paper discusses an ideal diode model with hot charge-transfer (CT) states to analyze the power conversion efficiency of an organic photocell. A free carrier generation mechanism via sunlight in an organic photocell consists of four microscopic processes: photon absorption, exciton dissociation, CT, and charge separation. The hot CT state effect has been actively investigated to understand the charge separation process. We previously reported a theoretical method to calculate the efficiency of the charge separation process via a hot CT state (T...
May 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28456171/on-the-role-of-the-entorhinal-cortex-in-the-effective-connectivity-of-the-hippocampal-formation
#8
Víctor J López-Madrona, Fernanda S Matias, Ernesto Pereda, Santiago Canals, Claudio R Mirasso
Inferring effective connectivity from neurophysiological data is a challenging task. In particular, only a finite (and usually small) number of sites are simultaneously recorded, while the response of one of these sites can be influenced by other sites that are not being recorded. In the hippocampal formation, for instance, the connections between areas CA1-CA3, the dentate gyrus (DG), and the entorhinal cortex (EC) are well established. However, little is known about the relations within the EC layers, which might strongly affect the resulting effective connectivity estimations...
April 2017: Chaos
https://www.readbyqxmd.com/read/28439520/relationship-between-relative-cerebral-blood-flow-relative-cerebral-blood-volume-and-relative-cerebral-metabolic-rate-of-oxygen-in-the-preterm-neonatal-brain
#9
Mina Nourhashemi, Guy Kongolo, Mahdi Mahmoudzadeh, Sabrina Goudjil, Fabrice Wallois
The mechanisms responsible for coupling between relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and relative cerebral metabolic rate of oxygen ([Formula: see text]), an important function of the microcirculation in preterm infants, remain unclear. Identification of a causal relationship between rCBF-rCBV and [Formula: see text] in preterms may, therefore, help to elucidate the principles of cortical hemodynamics during development. We simultaneously recorded rCBF and rCBV and estimated [Formula: see text] by two independent acquisition systems: diffuse correlation spectroscopy and near-infrared spectroscopy, respectively, in 10 preterms aged between 28 and 35 weeks of gestational age...
April 2017: Neurophotonics
https://www.readbyqxmd.com/read/28435963/thermodynamic-and-morphological-characterization-of-turing-patterns-in-non-isothermal-reaction-diffusion-systems
#10
Horacio Serna, Alberto P Muñuzuri, Daniel Barragán
The effect of temperature on the bifurcation diagram and Turing instability domain under non isothermal conditions is studied in the reversible Gray-Scott model. After adding the energy balance to the cubic autocatalytic model, the thermostat temperature and heat transfer coefficient are used as control parameters in the Turing pattern formation. The patterns obtained in the domain of the thermal parameter are characterized by quantifying the overall entropy generation rate and two topological indices; Shannon entropy and Minkowski functionals...
April 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28430108/a-network-physiology-approach-to-the-assessment-of-the-link-between-sinoatrial-and-ventricular-cardiac-controls
#11
Alberto Porta, Vlasta Bari, Beatrice De Maria, Mathias Baumert
A network physiology approach to evaluate the strength of the directed interactions among cardiac controls at sinoatrial and ventricular levels and respiration (R) is proposed. The network is composed of three nodes (i.e. sinoatrial and ventricular cardiac controls and R) and their activity is exemplified by the variability of heart period (HP), the variability of the duration of the electrical activity of the heart approximated as the temporal distance between Q-wave onset and T-wave end or apex (i.e. QTe or QTa) and thoracic movements respectively...
April 21, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28415203/transfer-entropy-in-continuous-time-with-applications-to-jump-and-neural-spiking-processes
#12
Richard E Spinney, Mikhail Prokopenko, Joseph T Lizier
Transfer entropy has been used to quantify the directed flow of information between source and target variables in many complex systems. While transfer entropy was originally formulated in discrete time, in this paper we provide a framework for considering transfer entropy in continuous time systems, based on Radon-Nikodym derivatives between measures of complete path realizations. To describe the information dynamics of individual path realizations, we introduce the pathwise transfer entropy, the expectation of which is the transfer entropy accumulated over a finite time interval...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28402867/functional-connectivity-and-network-analysis-during-hypoactive-delirium-and-recovery-from-anesthesia
#13
Tianne Numan, Arjen J C Slooter, Arendina W van der Kooi, Annemieke M L Hoekman, Willem J L Suyker, Cornelis J Stam, Edwin van Dellen
OBJECTIVE: To gain insight in the underlying mechanism of reduced levels of consciousness due to hypoactive delirium versus recovery from anesthesia, we studied functional connectivity and network topology using electroencephalography (EEG). METHODS: EEG recordings were performed in age and sex-matched patients with hypoactive delirium (n=18), patients recovering from anesthesia (n=20), and non-delirious control patients (n=20), all after cardiac surgery. Functional and directed connectivity were studied with phase lag index and directed phase transfer entropy...
June 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28401525/new-world-tryptamine-hallucinogens-and-the-neuroscience-of-ayahuasca
#14
Dennis McKenna, Jordi Riba
New World indigenous peoples are noted for their sophisticated use of psychedelic plants in shamanic and ethnomedical practices. The use of psychedelic plant preparations among New World tribes is far more prevalent than in the Old World. Yet, although these preparations are botanically diverse, almost all are chemically similar in that their active principles are tryptamine derivatives, either DMT or related constituents. Part 1 of this paper provides an ethnopharmacological overview of the major tryptamine-containing New World hallucinogens...
April 2, 2017: Current Topics in Behavioral Neurosciences
https://www.readbyqxmd.com/read/28392760/accelerated-recovery-of-consciousness-after-general-anesthesia-is-associated-with-increased-functional-brain-connectivity-in-the-high-gamma-bandwidth
#15
Duan Li, Viviane S Hambrecht-Wiedbusch, George A Mashour
Recent data from our laboratory demonstrate that high-frequency gamma connectivity across the cortex is present during consciousness and depressed during unconsciousness. However, these data were derived from static and well-defined states of arousal rather than during transitions that would suggest functional relevance. We also recently found that subanesthetic ketamine administered during isoflurane anesthesia accelerates recovery upon discontinuation of the primary anesthetic and increases gamma power during emergence...
2017: Frontiers in Systems Neuroscience
https://www.readbyqxmd.com/read/28378705/comparison-of-connectivity-analyses-for-resting-state-eeg-data
#16
Elzbieta Olejarczyk, Laura Marzetti, Vittorio Pizzella, Filippo Zappasodi
OBJECTIVE: In the present work, a nonlinear measure (transfer entropy, TE) was used in a multivariate approach for the analysis of effective connectivity in high density resting state EEG data in eyes open and eyes closed. Advantages of the multivariate approach in comparison to the bivariate one were tested. Moreover, the multivariate TE was compared to an effective linear measure, i.e. directed transfer function (DTF). Finally, the existence of a relationship between the information transfer and the level of brain synchronization as measured by phase synchronization value (PLV) was investigated...
June 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/28372376/a-versatile-approach-to-vacuum-injection-casting-for-materials-research-and-development
#17
Donghua Xu, Yifan Xu
Vacuum injection casting (VIC) is important for research and development (R&D) of materials that are prone to oxidation at high temperatures, particularly metals and metallic alloys (e.g., metallic glasses and high entropy alloys). VIC in R&D laboratories often involves initial melting/alloying in a prior step, transporting the sample to a dedicated vacuum chamber, re-melting the sample in a quartz tube, and finally injecting the melt with an inert gas to a dedicated mold. Here we present a new approach to laboratory VIC that requires no sample transfer (for a variety of materials), no dedicated vacuum chamber/space nor dedicated mold, and hence provides more versatility and higher efficiency and yet lowers the capital equipment cost...
March 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28372065/end-correction-model-for-the-transfer-impedance-of-microperforated-panels-using-viscothermal-wave-theory
#18
Xianhui Li
Microperforated panels (MPPs) are efficient sound absorbers featuring microperforations with low porosity. Sound absorption occurs inside the perforations and their vicinity as well, which is represented with an end correction in the transfer impedance of the MPPs. Many empirical models for the end correction were derived from experiment or numerical simulation data. In order to validate these models, this paper presents an analytical solution of the end correction for sharp-edged circular perforations using viscothermal wave theory...
March 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28365435/a-dft-b3lyp-study-of-the-mechanisms-of-the-o2-formation-reaction-catalyzed-by-the-terpy-h2o-mn-iii-o-2mn-iv-oh2-terpy-no3-3-complex-a-paradigm-for-photosystem-ii
#19
Eduardo M Sproviero
We present a theoretical study of the reaction pathway for dioxygen molecular formation catalyzed by the [(terpy)(H2O)Mn(III)(O)2Mn(IV)(OH2) (terpy)](NO3)3 (terpy=2,2':6',2″-terpyridine) complex based on DFT-B3LYP calculations. In the initial state of the reaction, a partial oxido radical (0.44 spins) is formed ligated to Mn. This radical is involved in a nucleophylic attack by bulk water in the OO bond reaction formation step, in which the oxido fractional unpaired electron is delocalized toward the outermost Mn of the μ-oxo bridge, instead of the ligated Mn center...
February 20, 2017: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/28358850/adaptive-feature-selection-using-v-shaped-binary-particle-swarm-optimization
#20
Xuyang Teng, Hongbin Dong, Xiurong Zhou
Feature selection is an important preprocessing method in machine learning and data mining. This process can be used not only to reduce the amount of data to be analyzed but also to build models with stronger interpretability based on fewer features. Traditional feature selection methods evaluate the dependency and redundancy of features separately, which leads to a lack of measurement of their combined effect. Moreover, a greedy search considers only the optimization of the current round and thus cannot be a global search...
2017: PloS One
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