scholarly journals Information Geometry, Fluctuations, Non-Equilibrium Thermodynamics, and Geodesics in Complex Systems

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1393
Author(s):  
Eun-jin Kim
Keyword(s):  
Geometric Theory ◽  
Information Geometry ◽  
Mean Value ◽  
Time Dependent ◽  
Entropy Production Rate ◽  
Time Varying ◽  
Research Fields ◽  
Equilibrium Processes ◽  
Over Time ◽  
Non Equilibrium

Information theory provides an interdisciplinary method to understand important phenomena in many research fields ranging from astrophysical and laboratory fluids/plasmas to biological systems. In particular, information geometric theory enables us to envision the evolution of non-equilibrium processes in terms of a (dimensionless) distance by quantifying how information unfolds over time as a probability density function (PDF) evolves in time. Here, we discuss some recent developments in information geometric theory focusing on time-dependent dynamic aspects of non-equilibrium processes (e.g., time-varying mean value, time-varying variance, or temperature, etc.) and their thermodynamic and physical/biological implications. We compare different distances between two given PDFs and highlight the importance of a path-dependent distance for a time-dependent PDF. We then discuss the role of the information rate Γ=dLdt and relative entropy in non-equilibrium thermodynamic relations (entropy production rate, heat flux, dissipated work, non-equilibrium free energy, etc.), and various inequalities among them. Here, L is the information length representing the total number of statistically distinguishable states a PDF evolves through over time. We explore the implications of a geodesic solution in information geometry for self-organization and control.

scholarly journals A Tutorial on Evaluating the Time-Varying Discrimination Accuracy of Survival Models Used in Dynamic Decision Making

2018 ◽  
Vol 38 (8) ◽  
pp. 904-916 ◽  
Author(s):  
Aasthaa Bansal ◽  
Patrick J. Heagerty
Keyword(s):  
Decision Making ◽  
Statistical Methods ◽  
Sensitivity And Specificity ◽  
Prognostic Model ◽  
Dynamic Decision Making ◽  
Time Dependent ◽  
Survival Models ◽  
Biliary Cirrhosis ◽  
Time Varying ◽  
Over Time

Many medical decisions involve the use of dynamic information collected on individual patients toward predicting likely transitions in their future health status. If accurate predictions are developed, then a prognostic model can identify patients at greatest risk for future adverse events and may be used clinically to define populations appropriate for targeted intervention. In practice, a prognostic model is often used to guide decisions at multiple time points over the course of disease, and classification performance (i.e., sensitivity and specificity) for distinguishing high-risk v. low-risk individuals may vary over time as an individual’s disease status and prognostic information change. In this tutorial, we detail contemporary statistical methods that can characterize the time-varying accuracy of prognostic survival models when used for dynamic decision making. Although statistical methods for evaluating prognostic models with simple binary outcomes are well established, methods appropriate for survival outcomes are less well known and require time-dependent extensions of sensitivity and specificity to fully characterize longitudinal biomarkers or models. The methods we review are particularly important in that they allow for appropriate handling of censored outcomes commonly encountered with event time data. We highlight the importance of determining whether clinical interest is in predicting cumulative (or prevalent) cases over a fixed future time interval v. predicting incident cases over a range of follow-up times and whether patient information is static or updated over time. We discuss implementation of time-dependent receiver operating characteristic approaches using relevant R statistical software packages. The statistical summaries are illustrated using a liver prognostic model to guide transplantation in primary biliary cirrhosis.

Flexible Design of Systems Considering Time-Dependent Reliability

2015 ◽  
Author(s):  
Vijitashwa Pandey ◽  
Zissimos P. Mourelatos ◽  
Annette Skowronska
Keyword(s):  
Time Dependent ◽  
Time Varying ◽  
Repairable Systems ◽  
Flexible Design ◽  
Change Over Time ◽  
New Approach ◽  
Hydrokinetic Turbine ◽  
The Future ◽  
Over Time

Many repairable systems degrade with time and are subjected to time-varying loads. Their characteristics may change over time considerably, making the assessment of their performance and hence their design difficult. To address this issue, we introduce in this paper the concept of flexible design of repairable systems under time-dependent reliability considerations. In flexible design, the system can be modified in the future to accommodate uncertain events. As a result, regardless of how uncertainty resolves itself, a modification is available that will keep the system close to optimal provided failure events have been properly characterized. We discuss how flexible design of repairable systems requires a fundamentally new approach and demonstrate its advantages using the design of a hydrokinetic turbine. Our results show that long-term metrics are improved when time-dependent characteristics and flexibility are considered together.

Utility of serial measurement of biomarkers of cardiovascular stress and inflammation in systolic dysfunction

EP Europace ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 1044-1053
Author(s):  
Daniel P Morin ◽  
Ronald Chong-Yik ◽  
Sudarone Thihalolipavan ◽  
Yoaav S Krauthammer ◽  
Michael L Bernard ◽  
...  
Keyword(s):  
Time Dependent ◽  
Inflammatory Biomarkers ◽  
Left Ventricular Ejection ◽  
Time Varying ◽  
Laboratory Measurements ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Tnf Α ◽  
Ambulatory Patients ◽  
Over Time

Abstract Aims Evidence links markers of systemic inflammation and heart failure (HF) with ventricular arrhythmias (VA) and/or death. Biomarker levels, and the risk they indicate, may vary over time. We evaluated the utility of serial laboratory measurements of inflammatory biomarkers and HF, using time-dependent analysis. Methods and results We prospectively enrolled ambulatory patients with left ventricular ejection fraction (LVEF) ≤35% and a primary-prevention implanted cardioverter-defibrillator (ICD). Levels of established inflammatory biomarkers [C-reactive protein, erythrocyte sedimentation rate (ESR), suppression of tumourigenicity 2 (ST2), tumour necrosis factor alpha (TNF-α)] and brain natriuretic peptide (BNP) were assessed at 3-month intervals for 1 year. We assessed relationships between biomarkers modelled as time-dependent variables, VA, and death. Among 196 patients (66±14 years, LVEF 23±8%), 33 experienced VA, and 18 died. Using only baseline values, BNP predicted VA, and both BNP and ST2 predicted death. Using serial measurements at 3-month intervals, time-varying BNP independently predicted VA, and time-varying ST2 independently predicted death. C-statistic analysis revealed no significant benefit to repeated testing compared with baseline-only measurement. C-reactive protein, ESR, and TNF-α, either at baseline or over time, did not predict either endpoint. Conclusion In stable ambulatory patients with systolic cardiomyopathy and an ICD, BNP predicts ventricular tachyarrhythmia, and ST2 predicts death. Repeated laboratory measurements over a year’s time do not improve risk stratification beyond baseline measurement alone. Clinical Trial Registration Clinicaltrials.gov NCT01892462 (https://clinicaltrials.gov/ct2/show/NCT01892462).

Acoustic field and the entropy mode induced by it in a waveguide filled with some non-equilibrium gases

Open Physics ◽  
2013 ◽  
Vol 11 (3) ◽  
Author(s):  
Anna Perelomova
Keyword(s):  
Acoustic Field ◽  
Sound Propagation ◽  
Mean Value ◽  
Leading Order ◽  
Acoustic Beam ◽  
Weakly Nonlinear ◽  
Equilibrium Processes ◽  
Non Linear Propagation ◽  
Linear Propagation ◽  
Non Equilibrium

AbstractThe non-linear propagation of an acoustic beam in a rectangular waveguide is considered. The medium of sound propagation, is a gas where thermodynamically non-equilibrium processes take place: such as exothermic chemical reactions or excitation of vibrational degrees of a molecule’s freedom. The incident and reflected compounds of the acoustic field do not interact in the leading order in the case of periodic weakly nonlinear sound with zero mean value of velocity. The acoustic heating or cooling in a waveguide is discussed.

scholarly journals Information Geometry of Non-Equilibrium Processes in a Bistable System with a Cubic Damping

2017 ◽  
Author(s):  
Rainer Hollerbach ◽  
Eun-jin Kim
Keyword(s):  
Stochastic Systems ◽  
Entropy Change ◽  
Information Geometry ◽  
Rate Of Change ◽  
Bistable System ◽  
Equilibrium Processes ◽  
Probabilistic Description ◽  
The Difference ◽  
Comparison Of The Results ◽  
Non Equilibrium

A probabilistic description is essential for understanding the dynamics of stochastic systems far from equilibrium, given uncertainty inherent in the systems. To compare different Probability Density Functions (PDFs), it is extremely useful to quantify the difference among different PDFs by assigning an appropriate metric to probability such that the distance increases with the difference between the two PDFs. This metric structure then provides a key link between stochastic systems and information geometry. For a non-equilibrium process, we define an infinitesimal distance at any time by comparing two PDFs at times infinitesimally apart and sum these distances in time. The total distance along the trajectory of the system quantifies the total number of different states that the system undergoes in time, and is called the information length. By using this concept, we investigate the information geometry of non-equilibrium processes involved in disorder-order transitions between the critical and subcritical states in a bistable system. Specifically, we compute time-dependent PDFs, information length, the rate of change in information length, entropy change and Fisher information in disorder-to-order and order-to-disorder transitions, and discuss similarities and disparities between the two transitions. In particular, we show that the total information length in order-to-disorder transition is much larger than that in disorder-to-order transition, and elucidate the link to the drastically different evolution of entropy in both transitions. We also provide the comparison of the results with those in the case of the transition between the subcritical and supercritical states and discuss implications for fitness.

Multiplexed Laser Induced Fluorescence and Non-Equilibrium Processes in Arcjets.

1994 ◽  
Author(s):  
Dennis Keefer ◽  
Robert Rhodes ◽  
Trevor Moeller ◽  
David Burtner
Keyword(s):  
Laser Induced Fluorescence ◽  
Equilibrium Processes ◽  
Non Equilibrium

Robustness Over Time-Varying Channels in DNN-HMM ASR Based Human-Robot Interaction

2017 ◽  
Author(s):  
José Novoa ◽  
Jorge Wuth ◽  
Juan Pablo Escudero ◽  
Josué Fredes ◽  
Rodrigo Mahu ◽  
...  
Keyword(s):  
Human Robot Interaction ◽  
Time Varying ◽  
Robot Interaction ◽  
Time Varying Channels ◽  
Over Time

scholarly journals Detection of Acetaminophen and Its Glucuronide in Fingerprint by SALDI Mass Spectrometry Using Zeolite and Study of Time-Dependent Changes in Detected Ion Amount

Analytica ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 66-75
Author(s):  
Toshiki Horikoshi ◽  
Chihiro Kitaoka ◽  
Yosuke Fujii ◽  
Takashi Asano ◽  
Jiawei Xu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Glucuronic Acid ◽  
Laser Desorption ◽  
The Body ◽  
Time Dependent ◽  
Laser Desorption Ionization ◽  
Fingerprint Analysis ◽  
Desorption Ionization ◽  
Acid Conjugate ◽  
Over Time

The ingredients of an antipyretic (acetaminophen, AAP) and their metabolites excreted into fingerprint were detected by surface-assisted laser desorption ionization (SALDI) mass spectrometry using zeolite. In the fingerprint taken 4 h after AAP ingestion, not only AAP but also the glucuronic acid conjugate of AAP (GAAP), caffeine (Caf), ethenzamide (Eth), salicylamide (Sala; a metabolite of Eth), and urea were detected. Fingerprints were collected over time to determine how the amounts of AAP and its metabolite changed with time, and the time dependence of the peak intensities of protonated AAP and GAAP was measured. It was found that the increase of [GAAP+H]+ peak started later than that of [AAP+H]+ peak, reflecting the metabolism of AAP. Both AAP and GAAP reached maximum concentrations approximately 3 h after ingestion, and were excreted from the body with a half-life of approximately 3.3 h. In addition, fingerprint preservation was confirmed by optical microscopy, and fingerprint shape was retained even after laser irradiation of the fingerprint. Our method may be used in fingerprint analysis.

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