コロキウム

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

2020年6月25日(木) 15:00 - 16:30

巌佐 庸 (理化学研究所 数理創造プログラム (iTHEMS) 特別顧問 / 関西学院大学 教授 / 九州大学 名誉教授)

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(月) 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(金) 15:30 - 17:00

若山 正人 (理化学研究所 数理創造プログラム (iTHEMS) 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(水) 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(木) 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) 数理脳科学研究チーム 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

第10回 MACSコロキウム

2019年11月15日(金) 14:45 - 18:45

坂井 南美 (理化学研究所 開拓研究本部 (CPR) 坂井星・惑星形成研究室 主任研究員)
渡邊 一也 (京都大学 大学院理学研究科 教授)

14:45- ティータイム 15:00- 坂井 南美 博士「21世紀の天文学　構造形成学から物質科学へ」 16:15- 渡邊 一也 博士「有機固体中の電子励起状態ダイナミクス」 17:45- 継続討論会 第10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

Topological phases of matter and operator algebras

2019年10月4日(金) 15:30 - 17:00

河東 泰之 (理化学研究所 数理創造プログラム (iTHEMS) 客員主管研究員 / 東京大学 大学院数理科学研究科 教授)

Topological phases of matter are hot topics in recent physics and related to a wide range of mathematical fields. I will talk about their aspects related to operator algebras. Our emphasis will be on theory of tensor categories which describe interactions of anyons. This theory plays an important role in topological quantum computations. In theory of operator algebras, Jones initiated theory of subfactors and discovered the Jones polynomial, a new topological invariant for knots as an application. We apply this theory to mathematical studies of anyons.

会場: 大河内記念ホール

配信:計算科学研究棟 R511 / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

イベント公式言語: 英語

第9回 MACSコロキウム

2019年7月12日(金) 16:15 - 18:50

藤田 誠 (東京大学 大学院工学系研究科 教授)
森 和俊 (京都大学 大学院理学研究科 生物科学専攻 生物物理学教室 教授)

16:15- ティータイム 16:30- 藤田 誠 博士 「ひとりでに組み上がる分子」 17:50- 森 和俊 博士「タンパク質の品質管理」 第9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

Spacetime Geometry of Black Holes, Wormholes, and Time Machines

2019年7月2日(火) 15:30 - 17:00

Pei-Ming Ho (Distinguished Professor, Department of Physics, National Taiwan University, Taiwan)

Since the advent of General Relativity, people have found many solutions with interesting spacetime geometries. Most notably, the black holes have attracted a lot of attention for their roles in generating gravitational waves, and for inducing the information loss paradox. In this talk, we consider black holes amongst other geometric structures and investigate the subtlety involved in the quantum effect such as Hawking radiation. In this context, we mention wormholes and time machines, and explain how they are conceptually related to the geometry under the horizon of a black hole. There will also be comments on my recent research result about how quantum effect must be large for observers sitting on top of the black hole horizon.

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 R511 / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

イベント公式言語: 英語

Quantum computing: current status and prospects

2019年4月25日(木) 15:00 - 16:30

藤井 啓祐 (大阪大学 大学院基礎工学研究科 教授)

Supported by extensive experimental efforts for realization of quantum computing devices, quantum computers of a hundred qubits are now within reach in the near future. This level of a quantum computer is not enough for fully fledged fault-tolerant quantum computing, but is still expected to have computational advantage against classical computers. Such a noisy intermediate scale quantum computing (NISQ) device is thought to be a testbed for proof-of-principle experiments of quantum algorithms and verification of quantum physics in the limit of extremely high complexity. In this talk, I will provide a general introduction to quantum computing starting from how and for what quantum computers work. Then I will provide an overview of the current status and prospects of the field of quantum computing. As the final part, I will also talk about our own activities on quantum-classical hybrid algorithm, which is a kind of quantum algorithms specifically designed for the NISQ devices.

会場: 鈴木梅太郎記念ホール

配信:計算科学研究棟 R511 / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

イベント公式言語: 英語

第8回 MACSコロキウム・2019年度MACS 学生説明会

2019年4月12日(金) 15:00 - 17:30

千葉 逸人 (東北大学 材料科学高等研究所 (AIMR) 教授)

15:00- ティータイム・団らん 15:15- 千葉 逸人 博士 「同期現象の数理」 16:45- 2019年度MACS学生説明会 第8回MACSコロキウムは（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

配信:研究本館 2階 235号室

イベント公式言語: 日本語

ZetaValue2019-iTHEMS Special Mathematics Colloquium

2019年3月21日(木) 14:00 - 17:30

松本 耕二 (名古屋大学 教授)
Jörn Steuding (University of Würzburg, Germany)

Prof. Kohji Matsumoto (Nagoya University) "An overview of the theory of multiple zeta-functions" Multiple zeta-functions are generalizations of the Riemann zeta-function, and its theory has been rapidly developed in these decades. It is connected with various fields of mathematics and mathematical physics. In this talk I will give an overview of some part of recent developments, mainly from the analytic viewpoint. Prof. Jörn Steuding (University of Würzburg, Germany) "On the Infinite in Number Theory" Beginning with two simple examples from elementary number theory (one of diophantine origin and one of arithmetical nature), we discuss the role of “infinity” in number theory. We touch upon topics like how to find good rational approximations to irrational quantities and the distribution of prime numbers. We conclude with a motivation of the big open question in this field, namely, the Riemann hypothesis (one of the six unsolved millennium problems) and the Langlands program.

会場: 大河内記念ホール

イベント公式言語: 英語

Tropical Rain Forest

2019年2月21日(木) 15:30 - 17:00

佐竹 暁子 (九州大学 大学院理学研究院 数理生物学研究室 教授)

In a unique phenomenon restricted to the tropical rain forests in Southeast Asia, hundreds of plant species from dozens of families reproduce synchronously at irregular, multi-year intervals. Although several hypotheses have been proposed, the proximate environmental cues that synchronize these general flowering events are uncertain. Fortunately, accumulation of long-term data and advanced statistical and modeling techniques are starting to shed new light on phenology of tropical plants. In this talk, series of studies that integrate long-term field monitoring, gene expression analyses, and modeling will be presented.

会場: 大河内記念ホール

配信:計算科学研究棟 311会議室 / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

イベント公式言語: 英語

第7回 MACSコロキウム・2018年度MACS成果報告会

2019年2月7日(木) 15:00 - 17:30

土`山 明 (京都大学 大学院理学研究科 地球惑星科学専攻 教授)

15:00- ティータイム 15:15- 2018年度MACS成果報告会 16:40- 土`山 明 博士『～鉱物に耳をあてがう、地球と宇宙が聞こえる〜「はやぶさ」サンプルから聞こえてきたこと、「はやぶさ２」サンプルへの期待』 第7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

第6回 MACSコロキウム

2018年11月8日(木) 15:00 - 17:30

古澤 力 (理化学研究所 生命機能科学研究センター (BDR) 多階層生命動態研究チーム チームリーダー / 東京大学 教授)
高井 研 (海洋研究開発機構 深海・地殻内生物圏研究分野 分野長)

15:00- ティータイム 15:15- 古澤 力 博士「生物の状態変化をどのように記述すべきか：実験室進化と理論解析」 16:30- 高井 研 博士「では、教えてくれ。生命の起源の’生命’とはなんのことだ。’生命’ が何かを知らずに、生命の起源を研究していると言うのか？（海原雄山風に）」 第6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。おいしいケーキとクッキーもありますよ。

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

Economic Networks: a Physicist's View

2018年10月3日(水) 15:00 - 16:30

青山 秀明 (理化学研究所 数理創造プログラム (iTHEMS) 客員主管研究員 / 京都大学 大学院理学研究科 教授)

Economic phenomena occur on networks formed by agents, such as firms and financial institutions. In order to understand the dynamic nature of economy, we need to understand structures of those networks and interactions between economic agents on it. In this talk, I will review several important research results on this theme, most of which uses Japanese rich, actual (not simulated) network data, including trade (production) network of about one million firms. Community structures, simulation of effect of natural disasters, new methodology required for such inquiry are some of the topics to be covered.

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 R511 / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

イベント公式言語: 英語

Bell's Theorem, Entanglement, Quantum Teleportation and All That

2018年7月19日(木) 16:00 - 17:30

Anthony James Leggett (Professor, University of Illinois at Urbana-Champaign, USA)

iTHEMS-CEMS Joint Colloquium. Professor Leggett is widely recognized as a world leader in the theory of low-temperature physics, and his pioneering work on superfluidity was recognized by the 2003 Nobel Prize in Physics. Abstract: One of the most surprising aspects of quantum mechanics is that under certain circumstances it does not allow individual physical systems, even when isolated, to possess properties in their own right. This feature, first clearly appreciated by John Bell in 1964, has over the last half-century been tested experimentally and found (in most people's opinion) to be spectacularly confirmed. More recently it has been realized that it permits various operations which are classically impossible, such as "teleportation" and secure-in-principle cryptography. This talk is a very basic introduction to the subject, which requires only elementary quantum mechanics.

会場: 大河内記念ホール

配信:計算科学研究棟 311会議室 / SUURI-COOL (Kyoto) / 東北大学 AIMR本館 2階セミナー室

イベント公式言語: 英語

第5回 MACSコロキウム

2018年7月3日(火) 15:00 - 17:30

藤井 啓祐 (京都大学 大学院理学研究科 特定准教授)
平島 崇男 (京都大学)

15:00- ティータイム 15:15- 藤井 啓祐 博士「量子コンピュータ：情報と物理、基礎と応用、理学と工学の交差点」 16:30- 平島 崇男 博士「沈み込み帯で活動する水の挙動の理解へ：青色片岩は有馬型熱水の起源」 第5回MACSコロキウム（iTHEMS協賛）です。理研和光へのSkype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。おいしいケーキとクッキーもありますよ。

会場: 京都大学 理学部 6号館 401講義室

配信:セミナー室 (160号室)

イベント公式言語: 日本語

Systems Biology of Cellular Rhythms

2018年7月2日(月) 15:00 - 16:30

Albert Goldbeter (Professor, Unit of Theoretical Chronobiology, Faculty of Sciences, Université Libre de Bruxelles, Belgium)

Rhythmic phenomena occur at all levels of biological organization, with periods ranging from milliseconds to years. Among biological rhythms, circadian clocks, of a period close to 24h, play a key role as they allow the adaptation of living organisms to the alternation of day and night. Biological rhythms represent a phenomenon of temporal self-organization in the form of sustained oscillations of the limit cycle type. Mathematical models show how the emergent property of oscillatory behavior arises from molecular interactions in cellular regulatory networks, which explains why cellular rhythms represent a major research topic in systems biology. After providing an introduction to biological rhythms and their modeling, I will focus on mathematical models for two major examples of rhythmic behavior at the cellular level : the circadian clock and the cell cycle. The coupling of these rhythms allows for their synchronization and for the occurrence of more complex patterns of oscillatory behavior. I will discuss the reasons why models for cellular rhythms tend to become more complex, upon incorporating new experimental observations. The case of cellular rhythms allows us to compare the merits of simple versus complex models for the dynamics of biological systems.

会場: 鈴木梅太郎記念ホール

配信:計算科学研究棟 305-2会議室 / SUURI-COOL (Kyoto) / 東北大学 AIMR本館 2階セミナー室

イベント公式言語: 英語

On the interplay between intrinsic and extrinsic instabilities of spatially localized patterns

2018年6月7日(木) 15:00 - 16:30

西浦 廉政 (東北大学 材料科学高等研究所 (AIMR) 教授)

Spatially localized dissipative structures are observed in various fields, such as neural signaling, chemical reactions, discharge patterns, granular materials, vegetated landscapes, binary convection and block copolymer nanoparticles. These patterns are much simpler than single living cells, however they seem to inherit several characteristic “living state” features, such as generation of new patterns, self-replication, switching to new dynamics via collisions and adaptive morphological changes to environments. These behaviors stem from an interplay between the intrinsic instability of each localized pattern and the strength of external signals. To understand such an interplay, we explore the global geometric interrelation amongst all relevant solution branches of a corresponding system with approximate unfolding parameters. For instance, it has been uncovered that large deformation via strong collision is mapped into the network of unstable patterns in infinite dimensional space, and that an organizing center for 1D pulse generators is a double homoclinicity of butterfly type. Large deformation of patterns is unavoidable so that a global geometric structure formed by all relevant solution branches gives us much more insight rather than conventional PDE approaches. We illustrate the impact of this approach for the case of pulse generators. We also report on the recent exciting finding, namely the formation of exotic 3D nanoparticles of block copolymers caused by the interplay between internal repulsion and affinity to external solvent, which is consistent with experimental results.

会場: 仁科ホール

配信:計算科学研究棟 305-2会議室 / SUURI-COOL (Kyoto)

イベント公式言語: 英語