Entropy最新文献_第10页

Spatio-Temporal Analysis of Acute Myocardial Ischaemia Based on Entropy-Complexity Plane.

IF 2.1 3区物理与天体物理

Entropy Pub Date : 2024-12-26 DOI: 10.3390/e27010008

Esteban R Valverde, Victoria Vampa, Osvaldo A Rosso, Pedro D Arini

{"title":"Spatio-Temporal Analysis of Acute Myocardial Ischaemia Based on Entropy-Complexity Plane.","authors":"Esteban R Valverde, Victoria Vampa, Osvaldo A Rosso, Pedro D Arini","doi":"10.3390/e27010008","DOIUrl":"10.3390/e27010008","url":null,"abstract":"Myocardial ischaemia is a decompensation of the oxygen supply and demand ratio, often caused by coronary atherosclerosis. During the initial stage of ischaemia, the electrical activity of the heart is disrupted, increasing the risk of malignant arrhythmias. The aim of this study is to understand the differential behaviour of the ECG during occlusion of both the left anterior descending (LAD) and right anterior coronary artery (RCA), respectively, using spatio-temporal quantifiers from information theory. A standard 12-lead ECG was recorded for each patient in the database. The control condition was obtained initially. Then, a percutaneous transluminal coronary angioplasty procedure (PTCA), which encompassed the occlusion/reperfusion period, was performed. To evaluate information quantifiers, the Bandt and Pompe permutation method was used to estimate the probability distribution associated with the electrocardiographic vector modulus. Subsequently, we analysed the positioning in the H×C causal plane for the control and ischaemia. In LAD occlusion, decreased entropy and increased complexity can be seen, i.e., the behaviour is more predictable with an increase in the degree of complexity of the system. RCA occlusion had the opposite effects, i.e., the phenomenon is less predictable and exhibits a lower degree of organisation. Finally, both entropy and complexity decrease during the reperfusion phase in LAD and RCA cases.","PeriodicalId":11694,"journal":{"name":"Entropy","volume":"27 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11765037/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143032237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Multi-Agent Hierarchical Graph Attention Actor-Critic Reinforcement Learning.

IF 2.1 3区物理与天体物理

Entropy Pub Date : 2024-12-25 DOI: 10.3390/e27010004

Tongyue Li, Dianxi Shi, Songchang Jin, Zhen Wang, Huanhuan Yang, Yang Chen

{"title":"Multi-Agent Hierarchical Graph Attention Actor-Critic Reinforcement Learning.","authors":"Tongyue Li, Dianxi Shi, Songchang Jin, Zhen Wang, Huanhuan Yang, Yang Chen","doi":"10.3390/e27010004","DOIUrl":"10.3390/e27010004","url":null,"abstract":"Multi-agent systems often face challenges such as elevated communication demands, intricate interactions, and difficulties in transferability. To address the issues of complex information interaction and model scalability, we propose an innovative hierarchical graph attention actor-critic reinforcement learning method. This method naturally models the interactions within a multi-agent system as a graph, employing hierarchical graph attention to capture the complex cooperative and competitive relationships among agents, thereby enhancing their adaptability to dynamic environments. Specifically, graph neural networks encode agent observations as single feature-embedding vectors, maintaining a constant dimensionality irrespective of the number of agents, which improves model scalability. Through the \"inter-agent\" and \"inter-group\" attention layers, the embedding vector of each agent is updated into an information-condensed and contextualized state representation, which extracts state-dependent relationships between agents and model interactions at both individual and group levels. We conducted experiments across several multi-agent tasks to assess our proposed method's effectiveness, stability, and scalability. Furthermore, to enhance the applicability of our method in large-scale tasks, we tested and validated its performance within a curriculum learning training framework, thereby enhancing its transferability.","PeriodicalId":11694,"journal":{"name":"Entropy","volume":"27 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11764705/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143032155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Entropy Production in an Electro-Membrane Process at Underlimiting Currents-Influence of Temperature.

IF 2.1 3区物理与天体物理

Entropy Pub Date : 2024-12-25 DOI: 10.3390/e27010003

Juan Carlos Maroto, Sagrario Muñoz, Vicenta María Barragán

{"title":"Entropy Production in an Electro-Membrane Process at Underlimiting Currents-Influence of Temperature.","authors":"Juan Carlos Maroto, Sagrario Muñoz, Vicenta María Barragán","doi":"10.3390/e27010003","DOIUrl":"10.3390/e27010003","url":null,"abstract":"The entropy production in the polarization phenomena occurring in the underlimiting regime, when an electric current circulates through a single cation-exchange membrane system, has been investigated in the 3-40 °C temperature range. From the analysis of the current-voltage curves and considering the electro-membrane system as a unidimensional heterogeneous system, the total entropy generation in the system has been estimated from the contribution of each part of the system. Classical polarization theory and the irreversible thermodynamics approach have been used to determine the total electric potential drop and the entropy generation, respectively, associated with the different transport mechanisms in each part of the system. The results show that part of the electric power input is dissipated as heat due to both electric migration and diffusion ion transports, while another part is converted into chemical energy stored in the saline concentration gradient. Considering the electro-membrane process as an energy conversion process, an efficiency has been defined as the ratio between stored power and electric power input. This efficiency increases as both applied electric current and temperature increase.","PeriodicalId":11694,"journal":{"name":"Entropy","volume":"27 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11764488/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143032590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Kinetic Theory with Casimir Invariants-Toward Understanding of Self-Organization by Topological Constraints.

IF 2.1 3区物理与天体物理

Entropy Pub Date : 2024-12-25 DOI: 10.3390/e27010005

Zensho Yoshida

引用次数: 0

A Secure and Efficient White-Box Implementation of SM4.

IF 2.1 3区物理与天体物理

Entropy Pub Date : 2024-12-24 DOI: 10.3390/e27010001

Xiaobo Hu, Yanyan Yu, Yinzi Tu, Jing Wang, Shi Chen, Yuqi Bao, Tengyuan Zhang, Yaowen Xing, Shihui Zheng

{"title":"A Secure and Efficient White-Box Implementation of SM4.","authors":"Xiaobo Hu, Yanyan Yu, Yinzi Tu, Jing Wang, Shi Chen, Yuqi Bao, Tengyuan Zhang, Yaowen Xing, Shihui Zheng","doi":"10.3390/e27010001","DOIUrl":"10.3390/e27010001","url":null,"abstract":"Differential Computation Analysis (DCA) leverages memory traces to extract secret keys, bypassing countermeasures employed in white-box designs, such as encodings. Although researchers have made great efforts to enhance security against DCA, most solutions considerably decrease algorithmic efficiency. In our approach, the Feistel cipher SM4 is implemented by a series of table-lookup operations, and the input and output of each table are protected by affine transformations and nonlinear encodings generated randomly. We employ fourth-order non-linear encoding to reduce the loss of efficiency while utilizing a random sequence to shuffle lookup table access, thereby severing the potential link between memory data and the intermediate values of SM4. Experimental results indicate that the DCA procedure fails to retrieve the correct key. Furthermore, theoretical analysis shows that the techniques employed in our scheme effectively prevent existing algebraic attacks. Finally, our design requires only 1.44 MB of memory, significantly less than that of the known DCA-resistant schemes-Zhang et al.'s scheme (24.3 MB), Yuan et al.'s scheme (34.5 MB) and Zhao et al.'s scheme (7.8 MB). Thus, our SM4 white-box design effectively ensures security while maintaining a low memory cost.","PeriodicalId":11694,"journal":{"name":"Entropy","volume":"27 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11764595/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143032662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Martingale-Free Introduction to Conditional Gaussian Nonlinear Systems.

IF 2.1 3区物理与天体物理

Entropy Pub Date : 2024-12-24 DOI: 10.3390/e27010002

Marios Andreou, Nan Chen

{"title":"A Martingale-Free Introduction to Conditional Gaussian Nonlinear Systems.","authors":"Marios Andreou, Nan Chen","doi":"10.3390/e27010002","DOIUrl":"10.3390/e27010002","url":null,"abstract":"The conditional Gaussian nonlinear system (CGNS) is a broad class of nonlinear stochastic dynamical systems. Given the trajectories for a subset of state variables, the remaining follow a Gaussian distribution. Despite the conditionally linear structure, the CGNS exhibits strong nonlinearity, thus capturing many non-Gaussian characteristics observed in nature through its joint and marginal distributions. Desirably, it enjoys closed analytic formulae for the time evolution of its conditional Gaussian statistics, which facilitate the study of data assimilation and other related topics. In this paper, we develop a martingale-free approach to improve the understanding of CGNSs. This methodology provides a tractable approach to proving the time evolution of the conditional statistics by deriving results through time discretization schemes, with the continuous-time regime obtained via a formal limiting process as the discretization time-step vanishes. This discretized approach further allows for developing analytic formulae for optimal posterior sampling of unobserved state variables with correlated noise. These tools are particularly valuable for studying extreme events and intermittency and apply to high-dimensional systems. Moreover, the approach improves the understanding of different sampling methods in characterizing uncertainty. The effectiveness of the framework is demonstrated through a physics-constrained, triad-interaction climate model with cubic nonlinearity and state-dependent cross-interacting noise.","PeriodicalId":11694,"journal":{"name":"Entropy","volume":"27 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11764456/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143032660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Applications of Entropy in Data Analysis and Machine Learning: A Review. 熵在数据分析和机器学习中的应用综述。

IF 2.1 3区物理与天体物理

Entropy Pub Date : 2024-12-23 DOI: 10.3390/e26121126

Salomé A Sepúlveda-Fontaine, José M Amigó

{"title":"Applications of Entropy in Data Analysis and Machine Learning: A Review.","authors":"Salomé A Sepúlveda-Fontaine, José M Amigó","doi":"10.3390/e26121126","DOIUrl":"10.3390/e26121126","url":null,"abstract":"Since its origin in the thermodynamics of the 19th century, the concept of entropy has also permeated other fields of physics and mathematics, such as Classical and Quantum Statistical Mechanics, Information Theory, Probability Theory, Ergodic Theory and the Theory of Dynamical Systems. Specifically, we are referring to the classical entropies: the Boltzmann-Gibbs, von Neumann, Shannon, Kolmogorov-Sinai and topological entropies. In addition to their common name, which is historically justified (as we briefly describe in this review), another commonality of the classical entropies is the important role that they have played and are still playing in the theory and applications of their respective fields and beyond. Therefore, it is not surprising that, in the course of time, many other instances of the overarching concept of entropy have been proposed, most of them tailored to specific purposes. Following the current usage, we will refer to all of them, whether classical or new, simply as entropies. In particular, the subject of this review is their applications in data analysis and machine learning. The reason for these particular applications is that entropies are very well suited to characterize probability mass distributions, typically generated by finite-state processes or symbolized signals. Therefore, we will focus on entropies defined as positive functionals on probability mass distributions and provide an axiomatic characterization that goes back to Shannon and Khinchin. Given the plethora of entropies in the literature, we have selected a representative group, including the classical ones. The applications summarized in this review nicely illustrate the power and versatility of entropy in data analysis and machine learning.","PeriodicalId":11694,"journal":{"name":"Entropy","volume":"26 12","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11675792/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142946653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Refining the Allostatic Self-Efficacy Theory of Fatigue and Depression Using Causal Inference. 运用因果推理完善疲劳和抑郁的适应自我效能理论。

IF 2.1 3区物理与天体物理

Entropy Pub Date : 2024-12-23 DOI: 10.3390/e26121127

Alexander J Hess, Dina von Werder, Olivia K Harrison, Jakob Heinzle, Klaas Enno Stephan

{"title":"Refining the Allostatic Self-Efficacy Theory of Fatigue and Depression Using Causal Inference.","authors":"Alexander J Hess, Dina von Werder, Olivia K Harrison, Jakob Heinzle, Klaas Enno Stephan","doi":"10.3390/e26121127","DOIUrl":"https://doi.org/10.3390/e26121127","url":null,"abstract":"Allostatic self-efficacy (ASE) represents a computational theory of fatigue and depression. In brief, it postulates that (i) fatigue is a feeling state triggered by a metacognitive diagnosis of loss of control over bodily states (persistently elevated interoceptive surprise); and that (ii) generalization of low self-efficacy beliefs beyond bodily control induces depression. Here, we converted ASE theory into a structural causal model (SCM). This allowed identification of empirically testable hypotheses regarding causal relationships between the variables of interest. Applying conditional independence tests to questionnaire data from healthy volunteers, we sought to identify contradictions to the proposed SCM. Moreover, we estimated two causal effects proposed by ASE theory using three different methods. Our analyses identified specific aspects of the proposed SCM that were inconsistent with the available data. This enabled formulation of an updated SCM that can be tested against future data. Second, we confirmed the predicted negative average causal effect from metacognition of allostatic control to fatigue across all three different methods of estimation. Our study represents an initial attempt to refine and formalize ASE theory using methods from causal inference. Our results confirm key predictions from ASE theory but also suggest revisions which require empirical verification in future studies.","PeriodicalId":11694,"journal":{"name":"Entropy","volume":"26 12","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11675165/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142946606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Transpiling Quantum Assembly Language Circuits to a Qudit Form. 将量子汇编语言电路转换成Qudit形式。

IF 2.1 3区物理与天体物理

Entropy Pub Date : 2024-12-23 DOI: 10.3390/e26121129

Denis A Drozhzhin, Anastasiia S Nikolaeva, Evgeniy O Kiktenko, Aleksey K Fedorov

引用次数: 0

Fundamental Limits of an Irreversible Heat Engine. 不可逆热机的基本极限。

IF 2.1 3区物理与天体物理

Entropy Pub Date : 2024-12-23 DOI: 10.3390/e26121128

Rui Fu

引用次数: 0