Philosophical Transactions of the Royal Society A最新文献_第6页

Bounds on heat flux for Rayleigh–Bénard convection between Navier-slip fixed-temperature boundaries 在Navier-slip定温边界间的rayleigh - bsamadard对流的热通量边界

Philosophical Transactions of the Royal Society A Pub Date : 2021-09-27 DOI: 10.1098/rsta.2021.0025

Theodore D. Drivas, H. Nguyen, Camilla Nobili

引用次数: 6

The broad edge of synchronization: Griffiths effects and collective phenomena in brain networks 同步的宽边:大脑网络中的格里菲斯效应和集体现象

Philosophical Transactions of the Royal Society A Pub Date : 2021-09-24 DOI: 10.1098/rsta.2020.0424

Víctor Buendía, Pablo Villegas, R. Burioni, M. A. Muñoz

{"title":"The broad edge of synchronization: Griffiths effects and collective phenomena in brain networks","authors":"Víctor Buendía, Pablo Villegas, R. Burioni, M. A. Muñoz","doi":"10.1098/rsta.2020.0424","DOIUrl":"https://doi.org/10.1098/rsta.2020.0424","url":null,"abstract":"Many of the amazing functional capabilities of the brain are collective properties stemming from the interactions of large sets of individual neurons. In particular, the most salient collective phenomena in brain activity are oscillations, which require the synchronous activation of many neurons. Here, we analyse parsimonious dynamical models of neural synchronization running on top of synthetic networks that capture essential aspects of the actual brain anatomical connectivity such as a hierarchical-modular and core-periphery structure. These models reveal the emergence of complex collective states with intermediate and flexible levels of synchronization, halfway in the synchronous–asynchronous spectrum. These states are best described as broad Griffiths-like phases, i.e. an extension of standard critical points that emerge in structurally heterogeneous systems. We analyse different routes (bifurcations) to synchronization and stress the relevance of ‘hybrid-type transitions’ to generate rich dynamical patterns. Overall, our results illustrate the complex interplay between structure and dynamics, underlining key aspects leading to rich collective states needed to sustain brain functionality. This article is part of the theme issue ‘Emergent phenomena in complex physical and socio-technical systems: from cells to societies’.","PeriodicalId":20020,"journal":{"name":"Philosophical Transactions of the Royal Society A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74266841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 13

Emergence of functional information from multivariate correlations 从多变量关联中出现功能信息

Philosophical Transactions of the Royal Society A Pub Date : 2021-09-16 DOI: 10.1098/rsta.2021.0250

C. Adami, Nitash C G

引用次数: 2

Double transition in kinetic exchange opinion models with activation dynamics 具有激活动力学的动态交换意见模型中的双跃迁

Philosophical Transactions of the Royal Society A Pub Date : 2021-09-08 DOI: 10.1098/rsta.2021.0164

Marcelo A. Pires, N. Crokidakis

引用次数: 6

Large-scale flow in a cubic Rayleigh–Bénard cell: long-term turbulence statistics and Markovianity of macrostate transitions 立方rayleigh - bsamadard单元中的大尺度流动:长期湍流统计和宏观状态转变的马尔可夫性

Philosophical Transactions of the Royal Society A Pub Date : 2021-09-06 DOI: 10.1098/rsta.2021.0042

P. Maity, P. Koltai, J. Schumacher

{"title":"Large-scale flow in a cubic Rayleigh–Bénard cell: long-term turbulence statistics and Markovianity of macrostate transitions","authors":"P. Maity, P. Koltai, J. Schumacher","doi":"10.1098/rsta.2021.0042","DOIUrl":"https://doi.org/10.1098/rsta.2021.0042","url":null,"abstract":"We investigate the large-scale circulation (LSC) in a turbulent Rayleigh-Bénard convection flow in a cubic closed convection cell by means of direct numerical simulations at a Rayleigh number Ra = 106. The numerical studies are conducted for single flow trajectories up to 105 convective free-fall times to obtain a sufficient sampling of the four discrete LSC states, which can be summarized to one macrostate, and the two crossover configurations which are taken by the flow in between for short periods. We find that large-scale dynamics depends strongly on the Prandtl number Pr of the fluid which has values of 0.1, 0.7, and 10. Alternatively, we run an ensemble of 3600 short-term direct numerical simulations to study the transition probabilities between the discrete LSC states. This second approach is also used to probe the Markov property of the dynamics. Our ensemble analysis gave strong indication of Markovianity of the transition process from one LSC state to another, even though the data are still accompanied by considerable noise. It is based on the eigenvalue spectrum of the transition probability matrix, further on the distribution of persistence times and the joint distribution of two successive microstate persistence times. This article is part of the theme issue ‘Mathematical problems in physical fluid dynamics (part 1)’.","PeriodicalId":20020,"journal":{"name":"Philosophical Transactions of the Royal Society A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76191374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Income inequality and mobility in geometric Brownian motion with stochastic resetting: theoretical results and empirical evidence of non-ergodicity 具有随机重置的几何布朗运动中的收入不平等和流动性:非遍历性的理论结果和经验证据

Philosophical Transactions of the Royal Society A Pub Date : 2021-09-04 DOI: 10.1098/rsta.2021.0157

Viktor Stojkoski, Petar Jolakoski, Arnab K. Pal, Trifce Sandev, L. Kocarev, R. Metzler

{"title":"Income inequality and mobility in geometric Brownian motion with stochastic resetting: theoretical results and empirical evidence of non-ergodicity","authors":"Viktor Stojkoski, Petar Jolakoski, Arnab K. Pal, Trifce Sandev, L. Kocarev, R. Metzler","doi":"10.1098/rsta.2021.0157","DOIUrl":"https://doi.org/10.1098/rsta.2021.0157","url":null,"abstract":"We explore the role of non-ergodicity in the relationship between income inequality, the extent of concentration in the income distribution, and income mobility, the feasibility of an individual to change their position in the income rankings. For this purpose, we use the properties of an established model for income growth that includes ‘resetting’ as a stabilizing force to ensure stationary dynamics. We find that the dynamics of inequality is regime-dependent: it may range from a strictly non-ergodic state where this phenomenon has an increasing trend, up to a stable regime where inequality is steady and the system efficiently mimics ergodicity. Mobility measures, conversely, are always stable over time, but suggest that economies become less mobile in non-ergodic regimes. By fitting the model to empirical data for the income share of the top earners in the USA, we provide evidence that the income dynamics in this country is consistently in a regime in which non-ergodicity characterizes inequality and immobility. Our results can serve as a simple rationale for the observed real-world income dynamics and as such aid in addressing non-ergodicity in various empirical settings across the globe. This article is part of the theme issue ‘Kinetic exchange models of societies and economies’.","PeriodicalId":20020,"journal":{"name":"Philosophical Transactions of the Royal Society A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88280842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 25

Extreme events in transitional turbulence 过渡性湍流中的极端事件

Philosophical Transactions of the Royal Society A Pub Date : 2021-09-03 DOI: 10.1098/rsta.2021.0036

Sébastien Gomé, L. Tuckerman, D. Barkley

引用次数: 14

Kinetic exchange income distribution models with saving propensities: inequality indices and self-organized poverty level 具有储蓄倾向的动态交换收入分配模型:不平等指数与自组织贫困水平

Philosophical Transactions of the Royal Society A Pub Date : 2021-08-27 DOI: 10.1098/rsta.2021.0163

Sanjukta Paul, Sudip Mukherjee, Biji Joseph, A. Ghosh, B. Chakrabarti

{"title":"Kinetic exchange income distribution models with saving propensities: inequality indices and self-organized poverty level","authors":"Sanjukta Paul, Sudip Mukherjee, Biji Joseph, A. Ghosh, B. Chakrabarti","doi":"10.1098/rsta.2021.0163","DOIUrl":"https://doi.org/10.1098/rsta.2021.0163","url":null,"abstract":"We report the numerical results for the steady-state income or wealth distribution P(m) and the resulting inequality measures (Gini g and Kolkata k indices) in the kinetic exchange models of market dynamics. We study the variations of P(m) and of the indices g and k with the saving propensity λ of the agents, with two different kinds of trade (kinetic exchange) dynamics. In the first case, the exchange occurs between randomly chosen pairs of agents and in the next, one of the agents in the chosen pair is the poorest of all and the other agent is randomly picked up from the rest of the population (where, in the steady state, a self-organized poverty level or SOPL appears). These studies have also been made for two different kinds of saving behaviours. One, where each agent has the same value of λ (constant over time) and the other where λ for each agent can take two values (0 and 1), changing randomly over a fraction of time ρ(<1) of choosing λ=1. We find that the inequality decreases with increasing savings (λ); inequality indices (g and k) decrease and SOPL increases with increasing λ, indicating possible applications in economic policy making. This article is part of the theme issue ‘Kinetic exchange models of societies and economies’.","PeriodicalId":20020,"journal":{"name":"Philosophical Transactions of the Royal Society A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78558147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Einstein flow with matter sources: stability and convergence 爱因斯坦流的物质来源:稳定性和收敛性

Philosophical Transactions of the Royal Society A Pub Date : 2021-08-27 DOI: 10.1098/rsta.2021.0190

V. Moncrief, P. Mondal

引用次数: 0

Some unusual wormholes in general relativity 广义相对论中一些不寻常的虫洞

Philosophical Transactions of the Royal Society A Pub Date : 2021-08-23 DOI: 10.1098/rsta.2021.0176

K. Bronnikov

引用次数: 2