scholarly journals Information transfer in QT-RR dynamics: Application to QT-correction

2018 ◽  
Author(s):  
Ilya Potapov ◽  
Joonas Latukka ◽  
Jiyeong Kim ◽  
Perttu Luukko ◽  
Katriina Aalto-Setälä ◽  
...  
Keyword(s):  
Information Flow ◽  
Qt Interval ◽  
Information Transfer ◽  
Entropy Method ◽  
Information Flows ◽  
Healthy Individuals ◽  
Rr Interval ◽  
Model Free ◽  
Flow Asymmetry ◽  
Beating Rate

ABSTRACTThe relation between the electrical properties of the heart and the beating rate is essential for the heart functioning. This relation is central when calculating the “corrected QT interval” — an important measure of the risk of potentially lethal arrhythmias. We use the transfer entropy method from information theory to quantitatively study the mutual dynamics of the ventricular action potential duration (the QT interval) and the length of the beat-to-beat (RR) interval. We show that for healthy individuals there is a strong asymmetry in the information transfer: the information flow from RR to QT dominates over the opposite flow (from QT to RR), i.e. QT depends on RR to a larger extent than RR on QT. Moreover, the history of the intervals has a strong effect on the information transfer: at sufficiently long QT history length the information flow asymmetry inverts and the RR influence on QT dynamics weakens. Finally, we demonstrate that the widely used QT correction methods cannot properly capture the changes in the information flows between QT and RR. We conclude that our results obtained through a model-free informational perspective can be utilised to improve and test the QT correction schemes in clinics.

scholarly journals Transfer entropy as a tool for inferring causality from observational studies in epidemiology

2017 ◽  
Author(s):  
N. Ahmad Aziz
Keyword(s):  
Information Flow ◽  
Observational Studies ◽  
Epidemiological Data ◽  
Entropy Method ◽  
Transfer Entropy ◽  
Theoretic Approach ◽  
Information Theoretic ◽  
Clear Cut ◽  
Model Free ◽  
Obesity And Diabetes

AbstractRecently Wiener’s causality theorem, which states that one variable could be regarded as the cause of another if the ability to predict the future of the second variable is enhanced by implementing information about the preceding values of the first variable, was linked to information theory through the development of a novel metric called ‘transfer entropy’. Intuitively, transfer entropy can be conceptualized as a model-free measure of directed information flow from one variable to another. In contrast, directionality of information flow is not reflected in traditional measures of association which are completely symmetric by design. Although information theoretic approaches have been applied before in epidemiology, their value for inferring causality from observational studies is still unknown. Therefore, in the present study we use a set of simulation experiments, reflecting the most classical and widely used epidemiological observational study design, to validate the application of transfer entropy in epidemiological research. Moreover, we illustrate the practical applicability of this information theoretic approach to ‘real-world’ epidemiological data by demonstrating that transfer entropy is able to extract the correct direction of information flow from longitudinal data concerning two well-known associations, i.e. that between smoking and lung cancer and that between obesity and diabetes risk. In conclusion, our results provide proof-of-concept that the recently developed transfer entropy method could be a welcome addition to the epidemiological armamentarium, especially to dissect those situations in which there is a well-described association between two variables but no clear-cut inclination as to the directionality of the association.

scholarly journals Photoreceptive retinal ganglion cells control the information rate of the optic nerve

2018 ◽  
Vol 115 (50) ◽  
pp. E11817-E11826 ◽  
Author(s):  
Nina Milosavljevic ◽  
Riccardo Storchi ◽  
Cyril G. Eleftheriou ◽  
Andrea Colins ◽  
Rasmus S. Petersen ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Retinal Ganglion Cells ◽  
Information Flow ◽  
Information Transfer ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Ambient Light ◽  
Visual Responses ◽  
Light Irradiance ◽  
The Brain

Information transfer in the brain relies upon energetically expensive spiking activity of neurons. Rates of information flow should therefore be carefully optimized, but mechanisms to control this parameter are poorly understood. We address this deficit in the visual system, where ambient light (irradiance) is predictive of the amount of information reaching the eye and ask whether a neural measure of irradiance can therefore be used to proactively control information flow along the optic nerve. We first show that firing rates for the retina’s output neurons [retinal ganglion cells (RGCs)] scale with irradiance and are positively correlated with rates of information and the gain of visual responses. Irradiance modulates firing in the absence of any other visual signal confirming that this is a genuine response to changing ambient light. Irradiance-driven changes in firing are observed across the population of RGCs (including in both ON and OFF units) but are disrupted in mice lacking melanopsin [the photopigment of irradiance-coding intrinsically photosensitive RGCs (ipRGCs)] and can be induced under steady light exposure by chemogenetic activation of ipRGCs. Artificially elevating firing by chemogenetic excitation of ipRGCs is sufficient to increase information flow by increasing the gain of visual responses, indicating that enhanced firing is a cause of increased information transfer at higher irradiance. Our results establish a retinal circuitry driving changes in RGC firing as an active response to alterations in ambient light to adjust the amount of visual information transmitted to the brain.

scholarly journals Non-disclosure for distributed mobile code

2011 ◽  
Vol 21 (6) ◽  
pp. 1111-1181
Author(s):  
ANA ALMEIDA MATOS ◽  
JAN CEDERQUIST
Keyword(s):  
Programming Language ◽  
Information Flow ◽  
Flow Property ◽  
Mobile Code ◽  
Information Flows ◽  
Distributed Programs ◽  
Security Issues ◽  
Code Mobility ◽  
Global Computing ◽  
Language Based Security

With the emergence of the new possibilities offered by global computing, new security issues follow from the fact that these possibilities can be equally exploited by parties with malicious intentions. Many attacks arise at the application level, and can be tackled by means of programming language techniques. For instance, confidentiality can be violated during the execution of programs that reveal secret information. This kind of program behaviour can be avoided by information flow analyses that detect the encoding of illegal flows.This paper studies information flows that occur in distributed programs with code mobility from a language-based security perspective. New forms of security leaks that are introduced by code mobility, which we callmigration leaks, are presented and compared with well-known forms of illegal flow. We propose an information flow property that is adequate for networks consisting of a generalisation of the non-disclosure policy. We design a type and effect system for enforcing it on an expressive distributed calculus, and explain a soundness proof methodology in detail.

ASSOCIATION-BASED INFORMATION FLOW CONTROL IN OBJECT-ORIENTED SYSTEMS

2004 ◽  
Vol 14 (03) ◽  
pp. 291-322
Author(s):  
SHIH-CHIEN CHOU ◽  
YING-KAI WEN
Keyword(s):  
Flow Control ◽  
Information Flow ◽  
Information Leakage ◽  
Object Oriented ◽  
Control Model ◽  
Program Execution ◽  
Information Flows ◽  
Information Flow Control ◽  
Object Oriented Systems

Controlling information flows to prevent information leakage within an application is essential. According to the maturity of object-oriented techniques, many models were developed for the control in object-oriented systems. Since objects may be dynamically instantiated during program execution, controlling information flows among objects is difficult. Our research revealed that association is useful in the control. We developed an association-based information flow control model for object-oriented systems. It precisely controls information flows among objects through associations and constraints. It also offers features such as controlling method invocation through argument sensitivity, allowing declassification, allowing purpose-oriented method invocation, and precisely controlling write access. This paper proposes the model and the implementation of the model, which is composed of the language AbFlow (association-based flow) and its supporting environment.

Supply chain information governance: toward a conceptual framework

2019 ◽  
Vol 30 (2) ◽  
pp. 506-526 ◽  
Author(s):  
Joonhwan In ◽  
Randy Bradley ◽  
Bogdan C. Bichescu ◽  
Chad W. Autry
Keyword(s):  
Supply Chain ◽  
Conceptual Framework ◽  
Information Flow ◽  
Information Quality ◽  
Theoretical Framework ◽  
Performance Outcomes ◽  
Organizational Level ◽  
Information Flows ◽  
Content Type ◽  
Information Governance

Purpose The purpose of this paper is to propose a scalable conceptual framework for governance of supply chain (SC) information flows by re-contextualizing the organizational concept of information governance as an SC concept. Design/methodology/approach This study leverages the strategy-structure-process-performance (SSPP) theory base to explain how effective SC information governance relates to improved internal SC performance. Via an in-depth literature review followed by conceptual theory building, the key features of organizational-level information governance are cast into a theoretical framework. Findings This study presents the theoretical framework that explains how SC information governance should contribute to improved internal SC performance. The proposed framework provides a theoretical basis for future research on SC information governance and would become a useful first step to extend the concept of SC information governance at the SC level. Practical implications SC managers should be aware that information governance mechanisms, rather than the management of basic, information flow-directed processes, to yield the best performance outcomes. Because of the numerous touch points information has in complex SCs, managing the quality of SC information through broader, higher-level governance standards is more important than maximizing connectivity and information flows, and information governance structures/policies across organizations should be designed accordingly. Originality/value This study theoretically links SC information governance and internal SC performance via information quality. It also advances the understanding of SC information flow by challenging the implicit but flawed assumption that uniformity of information quality within the supply chain to create the best outcomes.

scholarly journals Stroke-related alterations in inter-areal communication revealed via Granger causality analysis

2021 ◽  
Author(s):  
Michele Allegra ◽  
Chiara Favaretto ◽  
Nicholas Metcalf ◽  
Maurizio Corbetta ◽  
Andrea Brovelli
Keyword(s):  
Functional Connectivity ◽  
Granger Causality ◽  
Resting State ◽  
Information Transfer ◽  
Large Scale ◽  
Functional Organization ◽  
Information Flows ◽  
Causality Analysis ◽  
Stroke Patients ◽  
Granger Causality Analysis

ABSTRACTNeuroimaging and neurological studies suggest that stroke is a brain network syndrome. While causing local ischemia and cell damage at the site of injury, stroke strongly perturbs the functional organization of brain networks at large. Critically, functional connectivity abnormalities parallel both behavioral deficits and functional recovery across different cognitive domains. However, the reasons for such relations remain poorly understood. Here, we tested the hypothesis that alterations in inter-areal communication underlie stroke-related modulations in functional connectivity (FC). To this aim, we used resting-state fMRI and Granger causality analysis to quantify information transfer between brain areas and its alteration in stroke. Two main large-scale anomalies were observed in stroke patients. First, inter-hemispheric information transfer was strongly decreased with respect to healthy controls. Second, information transfer within the affected hemisphere, and from the affected to the intact hemisphere was reduced. Both anomalies were more prominent in resting-state networks related to attention and language, and they were correlated with impaired performance in several behavioral domains. Overall, our results support the hypothesis that stroke perturbs inter-areal communication within and across hemispheres, and suggest novel therapeutic approaches aimed at restoring normal information flow.SIGNIFICANCE STATEMENTA thorough understanding of how stroke perturbs brain function is needed to improve recovery from the severe neurological syndromes affecting stroke patients. Previous resting-state neuroimaging studies suggested that interaction between hemispheres decreases after stroke, while interaction between areas of the same hemisphere increases. Here, we used Granger causality to reconstruct information flows in the brain at rest, and analyze how stroke perturbs them. We showed that stroke causes a global reduction of inter-hemispheric communication, and an imbalance between the intact and the affected hemisphere: information flows within and from the latter are impaired. Our results may inform the design of stimulation therapies to restore the functional balance lost after stroke.

scholarly journals Cardiomyocyte Deletion of Bmal1 Exacerbates QT- and RR-Interval Prolongation in Scn5a+/ΔKPQ Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Elizabeth A. Schroder ◽  
Jennifer L. Wayland ◽  
Kaitlyn M. Samuels ◽  
Syed F. Shah ◽  
Don E. Burgess ◽  
...  
Keyword(s):  
Heart Rate ◽  
Circadian Clock ◽  
Qt Interval ◽  
Adult Mouse ◽  
Interval Prolongation ◽  
Rr Interval ◽  
Adult Cardiomyocytes ◽  
Channel Expression ◽  
Cell Type Specific

Circadian rhythms are generated by cell autonomous circadian clocks that perform a ubiquitous cellular time-keeping function and cell type-specific functions important for normal physiology. Studies show inducing the deletion of the core circadian clock transcription factor Bmal1 in adult mouse cardiomyocytes disrupts cardiac circadian clock function, cardiac ion channel expression, slows heart rate, and prolongs the QT-interval at slow heart rates. This study determined how inducing the deletion of Bmal1 in adult cardiomyocytes impacted the in vivo electrophysiological phenotype of a knock-in mouse model for the arrhythmogenic long QT syndrome (Scn5a+/ΔKPQ). Electrocardiographic telemetry showed inducing the deletion of Bmal1 in the cardiomyocytes of mice with or without the ΔKPQ-Scn5a mutation increased the QT-interval at RR-intervals that were ≥130 ms. Inducing the deletion of Bmal1 in the cardiomyocytes of mice with or without the ΔKPQ-Scn5a mutation also increased the day/night rhythm-adjusted mean in the RR-interval, but it did not change the period, phase or amplitude. Compared to mice without the ΔKPQ-Scn5a mutation, mice with the ΔKPQ-Scn5a mutation had reduced heart rate variability (HRV) during the peak of the day/night rhythm in the RR-interval. Inducing the deletion of Bmal1 in cardiomyocytes did not affect HRV in mice without the ΔKPQ-Scn5a mutation, but it did increase HRV in mice with the ΔKPQ-Scn5a mutation. The data demonstrate that deleting Bmal1 in cardiomyocytes exacerbates QT- and RR-interval prolongation in mice with the ΔKPQ-Scn5a mutation.

scholarly journals Effective transfer entropy to measure information flows in credit markets

2021 ◽  
Author(s):  
Nicoló Andrea Caserini ◽  
Paolo Pagnottoni
Keyword(s):  
Credit Risk ◽  
Bond Market ◽  
Small Sample ◽  
Transfer Entropy ◽  
Information Flows ◽  
Directional Information ◽  
Crisis Period ◽  
Model Free ◽  
Effective Transfer ◽  
Sovereign Bond Markets

AbstractIn this paper we propose to study the dynamics of financial contagion between the credit default swap (CDS) and the sovereign bond markets through effective transfer entropy, a model-free methodology which enables to overcome the required hypotheses of classical price discovery measures in the statistical and econometric literature, without being restricted to linear dynamics. By means of effective transfer entropy we correct for small sample biases which affect the traditional Shannon transfer entropy, as well as we are able to conduct inference on the estimated directional information flows. In our empirical application, we analyze the CDS and bond market data for eight countries of the European Union, and aim to discover which of the two assets is faster at incorporating the information on the credit risk of the underlying sovereign. Our results show a clear and statistically significant prominence of the bond market for pricing the sovereign credit risk, especially during the crisis period. During the post-crisis period, instead, a few countries behave dissimilarly from the others, in particular Spain and the Netherlands.

scholarly journals Applying transfer entropy approach to investigate the information flow among ASEAN stock markets

2020 ◽  
Vol 4 (1) ◽  
pp. First
Author(s):  
Tran Thi Tuan Anh
Keyword(s):  
Information Flow ◽  
Stock Markets ◽  
Investment Strategy ◽  
The Philippines ◽  
Transfer Entropy ◽  
The Other ◽  
Information Flows ◽  
Research Results ◽  
Region Data ◽  
Asean Countries

This paper uses transfer entropy to measure and identify the information flows between stock markets in the ASEAN region. Data on daily closing stock indices, including Vietnam, the Philippines, Malaysia, Indonesia, Thailand, and Singapore, are collected for the period from March 2012 to October 2019 to calculate these transfer entropies. The research results of this article can be considered in two aspects: one is, how information flow originating from one market will be accepted by other markets and secondly, information flow that markets receive. From the perspective of incoming transfer entropy, Vietnam is the country most affected by information from the other ASEAN markets while Indonesia and Malaysia are the least affected. In terms of outgoing entropy, Thailand is the largest source of information flow to the ASEAN markets. Malaysia and the Philippines are the two countries that receive minor information impact from other countries. The research also reveals that the Singapore stock market is rather separate from the other ASEAN countries. The research results also imply that, for investors and policymakers, defining the information flows among ASEAN stock markets can help to predict market movements, thereby developing a suitable investment strategy or establishing appropriate management policies.

scholarly journals Self-organization and information transfer in Antarctic krill swarms

2021 ◽  
Author(s):  
Alicia L. Burns ◽  
Timothy M. Schaerf ◽  
Joseph T. Lizier ◽  
So Kawaguchi ◽  
Martin Cox ◽  
...  
Keyword(s):  
Information Flow ◽  
Social Factors ◽  
Information Transfer ◽  
Antarctic Krill ◽  
Keystone Species ◽  
Self Organization ◽  
Detailed Understanding ◽  
Individual Level ◽  
Directional Alignment ◽  
Swarming Behavior

AbstractAntarctic krill swarms are one of the largest known animal aggregations. However, despite being the keystone species of the Southern Ocean, little is known about how swarms are formed and maintained, and we lack a detailed understanding of the local interactions between individuals that provide the basis for these swarms. Here we analyzed the trajectories of captive, wild-caught krill in 3D to determine individual level interaction rules and quantify patterns of information flow. Our results suggest krill operate a novel form of collective organization, with measures of information flow and individual movement adjustments expressed most strongly in the vertical dimension, a finding not seen in other swarming species. In addition, local directional alignment with near neighbors, and strong regulation of both direction and speed relative to the positions of groupmates suggest social factors are vital to the formation and maintenance of swarms. This research represents a first step in understanding the fundamentally important swarming behavior of krill.

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