Philosophical Transactions of the Royal Society A最新文献_第9页

Freeman Dyson FRS (1923–2020)

Philosophical Transactions of the Royal Society A Pub Date : 2020-05-11 DOI: 10.1098/rsta.2020.0139

J. Dainton

引用次数: 0

On the universality of the frequency spectrum and band-gap optimization of quasicrystalline-generated structured rods. 关于准晶体生成的结构棒的频谱普遍性和带隙优化。

Philosophical Transactions of the Royal Society A Pub Date : 2020-01-10 Epub Date: 2019-11-25 DOI: 10.1098/rsta.2019.0240

Lorenzo Morini, Zafer Gökay Tetik, Gal Shmuel, Massimiliano Gei

{"title":"On the universality of the frequency spectrum and band-gap optimization of quasicrystalline-generated structured rods.","authors":"Lorenzo Morini, Zafer Gökay Tetik, Gal Shmuel, Massimiliano Gei","doi":"10.1098/rsta.2019.0240","DOIUrl":"10.1098/rsta.2019.0240","url":null,"abstract":"The dynamical properties of periodic two-component phononic rods, whose elementary cells are generated adopting the Fibonacci substitution rules, are studied through the recently introduced method of the toroidal manifold. The method allows all band gaps and pass bands featuring the frequency spectrum to be represented in a compact form with a frequency-dependent flow line on the surface describing their ordered sequence. The flow lines on the torus can be either closed or open: in the former case, (i) the frequency spectrum is periodic and the elementary cell corresponds to a canonical configuration, (ii) the band gap density depends on the lengths of the two phases; in the latter, the flow lines cover ergodically the torus and the band gap density is independent of those lengths. It is then shown how the proposed compact description of the spectrum can be exploited (i) to find the widest band gap for a given configuration and (ii) to optimize the layout of the elementary cell in order to maximize the low-frequency band gap. The scaling property of the frequency spectrum, that is a distinctive feature of quasicrystalline-generated phononic media, is also confirmed by inspecting band-gap/pass-band regions on the torus for the elementary cells of different Fibonacci orders. This article is part of the theme issue 'Modelling of dynamic phenomena and localization in structured media (part 2)'.","PeriodicalId":20020,"journal":{"name":"Philosophical Transactions of the Royal Society A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6894518/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80231095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Primordial black holes and the origin of the matter-antimatter asymmetry. 原始黑洞与物质-反物质不对称的起源。

Philosophical Transactions of the Royal Society A Pub Date : 2019-12-30 Epub Date: 2019-11-11 DOI: 10.1098/rsta.2019.0091

Juan García-Bellido

{"title":"Primordial black holes and the origin of the matter-antimatter asymmetry.","authors":"Juan García-Bellido","doi":"10.1098/rsta.2019.0091","DOIUrl":"10.1098/rsta.2019.0091","url":null,"abstract":"We review here a new scenario of hot spot electroweak baryogenesis where the local energy released in the gravitational collapse to form primordial black holes (PBHs) at the quark-hadron (QCD) epoch drives over-the-barrier sphaleron transitions in a far from equilibrium environment with just the standard model CP violation. Baryons are efficiently produced in relativistic collisions around the black holes and soon redistribute to the rest of the universe, generating the observed matter-antimatter asymmetry well before primordial nucleosynthesis. Therefore, in this scenario there is a common origin of both the dark matter to baryon ratio and the photon to baryon ratio. Moreover, the sudden drop in radiation pressure of relativistic matter at H0/W±/Z0 decoupling, the QCD transition and e+e- annihilation enhances the probability of PBH formation, inducing a multi-modal broad mass distribution with characteristic peaks at 10-6, 1, 30 and 106 M⊙, rapidly falling at smaller and larger masses, which may explain the LIGO-Virgo black hole mergers as well as the OGLE-GAIA microlensing events, while constituting all of the cold dark matter today. We predict the future detection of binary black hole (BBH) mergers in LIGO with masses between 1 and 5 M⊙, as well as above 80 M⊙, with very large mass ratios. Next generation gravitational wave and microlensing experiments will be able to test this scenario thoroughly. This article is part of a discussion meeting issue 'Topological avatars of new physics'.","PeriodicalId":20020,"journal":{"name":"Philosophical Transactions of the Royal Society A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6863483/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74570488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Coupling in complex systems as information transfer across time scales 复杂系统中信息跨时间尺度传递的耦合

Philosophical Transactions of the Royal Society A Pub Date : 2019-12-16 DOI: 10.1098/rsta.2019.0094

M. Paluš

{"title":"Coupling in complex systems as information transfer across time scales","authors":"M. Paluš","doi":"10.1098/rsta.2019.0094","DOIUrl":"https://doi.org/10.1098/rsta.2019.0094","url":null,"abstract":"Complex systems such as the human brain or the Earth's climate consist of many subsystems interacting in intricate, nonlinear ways. Moreover, variability of such systems extends over broad ranges of spatial and temporal scales and dynamical phenomena on different scales also influence each other. In order to explain how to detect cross-scale causal interactions, we review information-theoretic formulation of the Granger causality in combination with computational statistics (surrogate data method) and demonstrate how this method can be used to infer driver-response relations from amplitudes and phases of coupled nonlinear dynamical systems. Considering complex systems evolving on multiple time scales, the reviewed methodology starts with a wavelet decomposition of a multi-scale signal into quasi-oscillatory modes of a limited bandwidth, described using their instantaneous phases and amplitudes. Then statistical associations, in particular, causality relations between phases or between phases and amplitudes on different time scales are tested using the conditional mutual information. As an application, we present the analysis of cross-scale interactions and information transfer in the dynamics of the El Niño Southern Oscillation. This article is part of the theme issue ‘Coupling functions: dynamical interaction mechanisms in the physical, biological and social sciences’.","PeriodicalId":20020,"journal":{"name":"Philosophical Transactions of the Royal Society A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79499098","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: 9

Coupling functions in climate. 气候中的耦合功能。

Philosophical Transactions of the Royal Society A Pub Date : 2019-12-16 Epub Date: 2019-10-28 DOI: 10.1098/rsta.2019.0006

Woosok Moon, John S Wettlaufer

{"title":"Coupling functions in climate.","authors":"Woosok Moon, John S Wettlaufer","doi":"10.1098/rsta.2019.0006","DOIUrl":"10.1098/rsta.2019.0006","url":null,"abstract":"We examine how coupling functions in the theory of dynamical systems provide a quantitative window into climate dynamics. Previously, we have shown that a one-dimensional periodic non-autonomous stochastic dynamical system can simulate the monthly statistics of surface air temperature data. Here, we expand this approach to two-dimensional dynamical systems to include interactions between two sub-systems of the climate. The relevant coupling functions are constructed from the covariance of the data from the two sub-systems. We demonstrate the method on two tropical climate indices, the El-Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD), to interpret the mutual interactions between these two air-sea interaction phenomena in the Pacific and Indian Oceans. The coupling function reveals that the ENSO mainly controls the seasonal variability of the IOD during its mature phase. This demonstrates the plausibility of constructing a network model for the seasonal variability of climate systems based on such coupling functions. This article is part of the theme issue 'Coupling functions: dynamical interaction mechanisms in the physical, biological and social sciences'.","PeriodicalId":20020,"journal":{"name":"Philosophical Transactions of the Royal Society A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6833999/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89916349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

On the concept of dynamical reduction: the case of coupled oscillators. 关于动态还原的概念：耦合振荡器的案例。

Philosophical Transactions of the Royal Society A Pub Date : 2019-12-16 Epub Date: 2019-10-28 DOI: 10.1098/rsta.2019.0041

Yoshiki Kuramoto, Hiroya Nakao

{"title":"On the concept of dynamical reduction: the case of coupled oscillators.","authors":"Yoshiki Kuramoto, Hiroya Nakao","doi":"10.1098/rsta.2019.0041","DOIUrl":"10.1098/rsta.2019.0041","url":null,"abstract":"An overview is given on two representative methods of dynamical reduction known as centre-manifold reduction and phase reduction. These theories are presented in a somewhat more unified fashion than the theories in the past. The target systems of reduction are coupled limit-cycle oscillators. Particular emphasis is placed on the remarkable structural similarity existing between these theories. While the two basic principles, i.e. (i) reduction of dynamical degrees of freedom and (ii) transformation of reduced evolution equation to a canonical form, are shared commonly by reduction methods in general, it is shown how these principles are incorporated into the above two reduction theories in a coherent manner. Regarding the phase reduction, a new formulation of perturbative expansion is presented for discrete populations of oscillators. The style of description is intended to be so informal that one may digest, without being bothered with technicalities, what has been done after all under the word reduction. This article is part of the theme issue 'Coupling functions: dynamical interaction mechanisms in the physical, biological and social sciences'.","PeriodicalId":20020,"journal":{"name":"Philosophical Transactions of the Royal Society A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6834004/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75963144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Ramanujan's legacy: the work of the SASTRA prize winners† 拉马努金的遗产:SASTRA获奖者的作品†

Philosophical Transactions of the Royal Society A Pub Date : 2019-12-09 DOI: 10.1098/rsta.2018.0438

K. Alladi

引用次数: 0

Selmer groups in Iwasawa theory and congruences Iwasawa理论中的Selmer群与同余

Philosophical Transactions of the Royal Society A Pub Date : 2019-12-09 DOI: 10.1098/rsta.2018.0442

R. Sujatha

引用次数: 3

Srinivasa Ramanujan and signal-processing problems Srinivasa Ramanujan和信号处理问题

Philosophical Transactions of the Royal Society A Pub Date : 2019-12-09 DOI: 10.1098/rsta.2018.0446

P. Vaidyanathan, S. Tenneti

引用次数: 10

Asymptotics and Ramanujan's mock theta functions: then and now 渐近性和Ramanujan的模拟函数:过去和现在

Philosophical Transactions of the Royal Society A Pub Date : 2019-12-09 DOI: 10.1098/rsta.2018.0448

A. Folsom

{"title":"Asymptotics and Ramanujan's mock theta functions: then and now","authors":"A. Folsom","doi":"10.1098/rsta.2018.0448","DOIUrl":"https://doi.org/10.1098/rsta.2018.0448","url":null,"abstract":"This article is in commemoration of Ramanujan's election as Fellow of The Royal Society 100 years ago, as celebrated at the October 2018 scientific meeting at the Royal Society in London. Ramanujan's last letter to Hardy, written shortly after his election, surrounds his mock theta functions. While these functions have been of great importance and interest in the decades following Ramanujan's death in 1920, it was unclear how exactly they fit into the theory of modular forms—Dyson called this ‘a challenge for the future’ at another centenary conference in Illinois in 1987, honouring the 100th anniversary of Ramanujan's birth. In the early 2000s, Zwegers finally recognized that Ramanujan had discovered glimpses of special families of non-holomorphic modular forms, which we now know to be Bruinier and Funke's harmonic Maass forms from 2004, the holomorphic parts of which are called mock modular forms. As of a few years ago, a fundamental question from Ramanujan's last letter remained, on a certain asymptotic relationship between mock theta functions and ordinary modular forms. The author, with Ono and Rhoades, revisited Ramanujan's asymptotic claim, and established a connection between mock theta functions and quantum modular forms, which were not defined until 90 years later in 2010 by Zagier. Here, we bring together past and present, and study the relationships between mock modular forms and quantum modular forms, with Ramanujan's mock theta functions as motivation. In particular, we highlight recent work of Bringmann–Rolen, Choi–Lim–Rhoades and Griffin–Ono–Rolen in our discussion. This article is largely expository, but not exclusively: we also establish a new interpretation of Ramanujan's radial asymptotic limits in the subject of topology. This article is part of a discussion meeting issue ‘Srinivasa Ramanujan: in celebration of the centenary of his election as FRS’.","PeriodicalId":20020,"journal":{"name":"Philosophical Transactions of the Royal Society A","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83001737","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: 0