コロキウム

How is turbulence born: Statistical mechanics and ecological collapse in transitional fluids

2022年4月22日15:00 - 16:30

Dr. Hong-Yan Shih (Assistant Research Fellow, Institute of Physics, Academia Sinica, Taiwan)

The onset of turbulence is ubiquitous in daily life and is important in various industrial applications, yet how fluids become turbulent has remained unsolved for more than a century. Recent experiments in pipe flow finally quantified this transition, showing that non-trivial statistics and spatiotemporal complexity develop as the flow velocity is increased. Combining numerical simulations of the hydrodynamics equations and an effective theory from statistical mechanics, we discovered the surprising fact that fluid behavior at the transition is governed by the emergent predator-prey dynamics, leading to the mathematical prediction that the laminar-turbulent transition is analogous to an ecosystem on the edge of extinction. This prediction demonstrates that the laminar-turbulent transition is a non-equilibrium phase transition in the directed percolation universality class, and provides a unified picture of transition to turbulence in various systems. I will also show our recent progresses on transitional turbulence, including how an extended ecological model with energy balance successfully recapitulates the spatiotemporal patterns beyond the critical point, and the determination of the critical behavior and an emergent novel phase under interactions in the experimental collaboration.

会場: via Zoom

イベント公式言語: 英語

第19回 MACSコロキウム・2022年度MACS学生説明会

2022年4月18日15:00 - 17:40

井上 康博 (京都大学 大学院工学研究科 マイクロエンジニアリング専攻 教授)

15:00- 井上 康博 博士 「形態形成の多細胞力学シミュレーション」 16:05- 2022年度MACS学生説明会 17:10- 各スタディグループの個別説明

会場: via Zoom

イベント公式言語: 日本語

第18回 MACSコロキウム

2022年2月14日15:00 - 17:30

長田 哲也 (京都大学 大学院理学研究科 物理学・宇宙物理学専攻 宇宙物理学教室 教授)

15:00- 長田 哲也 博士 「赤外線天文学と数理－不如楽之者」 16:05- 2021年度MACS成果報告会 16:30- 各スタディグループの意見交換

会場: via Zoom

イベント公式言語: 日本語

第17回 MACSコロキウム

2021年11月19日15:00 - 18:00

早水 桃子 (早稲田大学 理工学術院 基幹理工学部 講師 (専任) / 国立研究開発法人科学技術振興機構 (JST) さきがけ研究者)
倉谷 滋 (理化学研究所 開拓研究本部 (CPR) 倉谷形態進化研究室 主任研究員 / 理化学研究所 生命機能科学研究センター (BDR) 形態進化研究チーム チームリーダー)

15:00- 早水 桃子 博士 「進化の系統樹と系統ネットワークに関する組合せ論」 16:15- 倉谷 滋 博士「進化と発生のパターンについて」 17:15- 継続討論会

会場: via Zoom

イベント公式言語: 日本語

High-Energy Neutrino Astrophysics in the Multimessenger Era

2021年10月28日15:00 - 16:30

村瀬 孔大 (Associate Professor, Pennsylvania State University, USA)

The discovery of high-energy cosmic neutrinos opened a new window of astroparticle physics. Their origin is a new mystery in the field, which is tightly connected to the long-standing puzzle about the origin of cosmic rays. I will give an overview of the latest results on high-energy neutrino and cosmic-ray observations, and demonstrate the power of "multimessenger" approaches. In particular, I will show that the observed fluxes of neutrinos, gamma rays, and extragalactic cosmic rays can be understood in a unified manner. I will also highlight the recent developments about astrophysical neutrino emission from supermassive black holes and violent transient phenomena. Possibilities of utilizing high-energy neutrinos as a probe of heavy dark matter may be discussed.

会場: via Zoom

イベント公式言語: 英語

Finding Gravitational Waves from the Early Universe

2021年9月27日16:00 - 17:30

小松 英一郎 (Director, Max Planck Institute for Astrophysics, Germany)

The Cosmic Microwave Background (CMB) gives a photographic image of the Universe when it was still an “infant”. We have been using it to test our ideas about the origin of the Universe. The CMB research told us a remarkable story: the structure we see in our Universe such as galaxies, stars, planets, and eventually ourselves originated from tiny quantum fluctuations in the period of the early Universe called cosmic inflation. While we have accumulated strong evidence for this picture, the extraordinary claim requires extraordinary evidence. The last prediction of inflation that is yet to be confirmed is the existence of primordial gravitational waves whose wavelength can be as big as billions of light years. To this end we have proposed to JAXA a new satellite mission called LiteBIRD, whose primary scientific goal is to find signatures of gravitational waves in the polarisation of the CMB. In this presentation we describe physics of gravitational waves from inflation, and the LiteBIRD proposal.

会場: via Zoom

イベント公式言語: 英語

Quantitative Population Dynamics in Interdisciplinary Biology

2021年7月8日10:30 - 12:00

岩見 真吾 (名古屋大学 大学院理学研究科 生命理学専攻 教授)

Through the course of life, from the moment of birth till death, an organism will achieve various states of equilibrium or ‘homeostasis’ which will inevitably encounter perturbations. The processes of cell growth, differentiation, infection, mutation, evolution and adaptation work together as a coordinated ‘system’, described by mathematical models for population dynamics, to maintain a healthy state. Any disruptions to this system leads to disease including infection, allergy, cancer, and aging. We are conducting interdisciplinary research to elucidate “Quantitative Population Dynamics” through the course of life with original mathematical theory and computational simulation, which are both our CORE approach. Our mathematical model-based approach has quantitatively improved a current gold-standard approach essentially relying on the statistical analysis of “snapshot data” during dynamic interaction processes in life sciences research. In this talk, I will explain how our interdisciplinary approach extends our understanding for complicated clinical data and apply real world problem with an example of the Novel Coronavirus Disease, COVID-19.

会場: via Zoom

イベント公式言語: 英語

第16回 MACSコロキウム

2021年7月5日15:00 - 18:00

谷村 吉隆 (京都大学 大学院理学研究科 教授)
西森 秀稔 (数理創造プログラム 客員主管研究員 / 東京工業大学 特任教授)

15:00- 谷村 吉隆 博士 「生物化学物理を支配する非平衡量子統計力学」 16:15- 西森 秀稔 博士 「量子アニーリングを用いた量子系のシミュレーション」 17:15- 継続討論会

会場: via Zoom

イベント公式言語: 日本語

第15回 MACSコロキウム・2021年度MACS学生説明会

2021年4月23日15:00 - 17:30

石川 博 (早稲田大学 理工学術院 基幹理工学部 情報理工学科 教授)

15:00- 石川 博 博士「機械に認識させるとはどういうことか」 16:05- 2021年度MACS学生説明会

会場: via Zoom

イベント公式言語: 日本語

Mirror symmetry and KAM theory

2021年4月16日13:30 - 15:00

深谷 賢治 (Permanent Member, Simons Center for Geometry and Physics, Stony Brook University, New York, USA)

13:30pm-15:00pm (JST) Mirror symmetry is a phenomenon discovered in String theory and is much discussed recently in mathematics especially in the field of complex (algebraic) geometry and symplectic geometry. Strominger-Yau-Zaslow found that this phenomenon is closed related to a Lagrangian torus fibration. In an integrable system in Hamiltonian dynamics, the phase space is foliated by Lagrangian tori. I would like to explain a program that the Lagrangian torus fibration found by Strominger-Yau-Zaslow could be regarded as one appearing certain integrable system and KAM theory (which describes a amiltonian dynamics that is a perturbation of an integrable system) could appear in the situation of Mirror symmetry.

会場: via Zoom

イベント公式言語: 英語

第14回 MACSコロキウム・2020年度MACS成果報告会

2021年2月17日15:00 - 17:30

金子 善宏 (京都大学 大学院理学研究科 地球惑星科学専攻 地球物理学教室 准教授)

15:00- 金子 善宏 博士「数値シミュレーションで地震現象の謎に迫る」 16:05- 2020年度MACS成果報告会 16:30- 各スタディグループの意見交換

会場: via Zoom

イベント公式言語: 日本語

Geometry (形); Inconspicuous regulator that determines the fate of cells

2020年12月14日10:00 - 11:30

Prof. Sungrim Seirin-Lee (広島大学 教授)

December 14 at 10:00-11:30, 2020 (JST) December 13 at 20:00-21:30, 2020 (EST) In the history of mathematical study in pattern formation, the effect of domain has been considered as an important factor that can regulate spatial patterning. However, it is still unknown in biology how the geometry of the domain such as nuclear or cellular shapes can directly regulate the cell fate. In this talk, I will introduce two studies of spatial reorganization in chromatin and cellular dynamics and show that the domain is likely to play a critical role in determining the cell function.

会場: via Zoom

イベント公式言語: 英語

The Unreasonable Effectiveness of Quantum Theory in Mathematics

2020年11月26日10:00 - 11:30

Prof. Robbert Dijkgraaf (Director, Institute for Advanced Study in Princeton, USA)

November 26 at 10:00-11:30, 2020 (JST) November 25 at 20:00-21:30, 2020 (EST) The physical concepts of quantum theory, in particular of quantum gravity and string theory, have proven to be extremely powerful in addressing deep problems in pure mathematics, from knot invariants to algebraic geometry. Is there such a thing as “quantum mathematics”? Should we add Feynman diagrams, strings, branes and black holes to the language of mathematics?

会場: via Zoom

イベント公式言語: 英語

第13回 MACSコロキウム

2020年11月13日15:00 - 18:00

川口 真也 (京都大学 大学院理学研究科 生物物理学教室 高次情報形成学講座 教授)
杉田 有治 (数理創造プログラム 上級研究員 / 理化学研究所 開拓研究本部 (CPR) 杉田理論分子科学研究室 主任研究員)

15:00- 川口 真也 博士「神経系のやわらかい情報処理」 16:15- 杉田 有治 博士「計算機シミュレーションで細胞の中を観る」 17:15- 継続討論会

会場: via Zoom

イベント公式言語: 日本語

第12回 MACSコロキウム・2020年度MACS学生説明会

2020年7月17日15:00 - 18:30

平岡 裕章 (京都大学 高等研究院 (KUIAS) 教授 / 理化学研究所 革新知能統合研究センター (AIP) トポロジカルデータ解析チーム チームリーダー)
田中 求

15:00- 平岡 裕章 博士「トポロジカルデータ解析：理論と応用」 16:15- 令和2年度 MACS 学生説明会 17:30- 田中 求 博士「臨床医学の課題に切り込む数物科学」

会場: via Zoom

イベント公式言語: 日本語

iTHEMS Intensive Course [4] : "Adaptive strategies of organisms, their mathematical bases" - Cancer as a mini-evolutionary process

2020年6月25日15:00 - 16:30

巌佐 庸 (数理創造プログラム 特別顧問 / 関西学院大学 教授)

Living systems exhibit features distinct from nonliving physical systems: their structure and behaviors appear to be chosen adaptive. They are the outcomes of evolution. Mathematical formalisms developed in engineering and social sciences (e.g. control theory, game theory, evolutionary game theory) are sometimes very useful in biology.

会場: via Zoom

イベント公式言語: 英語

Emergence of life in an inflationary universe

2020年5月11日15:30 - 17:00

戸谷 友則 (東京大学 大学院理学系研究科 天文学専攻 教授)

The origin of life may be the greatest mystery in natural science. Especially, we know almost nothing about how the first biological molecule (possibly an RNA) appeared from abiotic chemical processes. A widespread notion is that the abiogenesis probability is extremely low when we consider only random chemical reactions to polymerize a large biological molecule. However, we do not know any more efficient polymerization process expected to work in a realistic prebiotic environment. Here, I consider this problem from a viewpoint of cosmology. Cosmologists agree that the universe created by an inflation should extend far beyond the observable universe (13.8 billion light year radius). Then the inflationary universe may be sufficiently large to produce many abiogenesis events, even if we consider only the basic random polymerization. I will give a quantitative answer to this question, and discuss various implications about the origin-of-life studies.

会場: via Zoom

イベント公式言語: 英語

Interaction Models in Quantum Optics, Representation Theory and Number Theory

2020年4月10日15:30 - 17:00

若山 正人 (数理創造プログラム 特別顧問 / 東京理科大学 副学長)

Recently, interaction models originated in quantum optics, with the quantum Rabi model (QRM) as a distinguished representative, are appearing ubiquitously in various quantum systems including cavity and circuit quantum electrodynamics, quantum dots and artificial atoms, with potential applications to quantum information technologies such as quantum computing. Together with the integrability of QRM, demonstrated by Daniel Braak in 2011, this has led to wide discussion and development of various aspect of the QRM and its generalizations from the point of view of theoretical physics and mathematics. In this talk, firstly, we characterize the structure of the spectra of QRM and its asymmetric version via sℓ2-representations. Secondly, we introduce the non-commutative harmonic oscillator, which may be considered to be a “cover” of the QRM in the Heun ODE picture, and describe certain number theoretical aspects arising from its spectral zeta function. Further, we discuss the heat kernel and partition function of the QRM toward the number theoretical investigation of the model. In addition, a number of related open problems will be presented.

会場: via Zoom

イベント公式言語: 英語

第11回 MACSコロキウム・2019年度MACS成果報告会

2020年2月19日15:00 - 17:30

畑 浩之 (京都大学 大学院理学研究科 教授)

15:00- ティータイム 15:15- 畑 浩之 博士「弦の場の理論とその数理」 16:40- 2019年度MACS成果報告会 第11回MACSコロキウム（iTHEMS協賛）です。理研和光への配信がありますが、可能な方は是非京都で参加してください。おいしいスイーツもありますよ。

会場: 京都大学 理学部 6号館 401講義室

イベント公式言語: 日本語

Exploring the learning principle in the brain

2020年1月16日15:30 - 17:00

豊泉 太郎 (理化学研究所 脳神経科学研究センター (CBS) チームリーダー)

Animals adapt to the environment for survival. Synaptic plasticity is considered a major mechanism underlying this process. However, the best-known form of synaptic plasticity, i.e., Hebbian plasticity that depends on pre- and post-synaptic activity, can surge coincident activity in model neurons beyond a physiological range. Our lab has explored how neural circuits learn about the environment by synaptic plasticity. The instability of Hebbian plasticity could be mitigated by a global factor that modulates its outcome. For example, TNF-alpha that mediates homeostatic synaptic scaling is released by glia, reflecting the activity level of surrounding neurons. I show that a specific interaction of Hebbian plasticity with this global factor accounts for the time course of adaptation to the altered environment (Toyoizumi et al. 2015). At a more theoretical level, I ask what is the optimal synaptic plasticity rule for achieving an efficient representation of the environment. A solution is the error-gated Hebbian rule, whose update is proportional to the product of Hebbian change and a specific global factor. I show that this rule, suitable also in neuromorphic devices, robustly extracts hidden independent sources in the environment (Isomura and Toyoizumi 2016, 2018, 2019). Finally, I introduce that synapses change by intrinsic spine dynamics, even in the absence of synaptic plasticity. I show that physiological spine-volume distribution and stable cell assemblies are both achieved when intrinsic spine dynamics are augmented in a model (Humble et al.2019).

会場: 統合支援施設（第一食堂） 2階 大会議室

配信:計算科学研究棟 R311 / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

イベント公式言語: 英語