MACS10周年記念コロキウム・2024年度MACS成果報告会

2025年2月19日(水) 14:45 - 18:30

國府 寛司 (京都大学 理事)
高橋 淑子 (京都大学 大学院理学研究科 生物科学専攻 教授)

14:45-15:00 ティータイムディスカッション [15:00-16:30 第1部 MACS10周年記念コロキウム] 15:05-15:05 はじめに（佐々真一 SACRA学際融合部門長） 15:05-15:30 講演1「MACS はどのように始まったか？」國府寛司 博士 （数学・数理解析専攻 教授） 2016年5月のキックオフシンポジウムから始まったMACSが2025年度で10年目を迎えるという時期にあたり，その立ち上げの時のことを振り返ってお話したい．特に，10年前にどのような人々がどのようなことを考えて，それがMACSプログラムに至ったのか，また当初MACSでやりたいと思っていたができなかったことなどを思い出し，この10年のMACSの歩みや，MACSとその後の京大理学の諸活動との関わりなどについて，いくつか取り上げてお話してみたい． 15:30-15:55 講演2「MACSから生まれた躍動感」高橋淑子 博士 （生物科学専攻 教授） 「MACS」は語呂がよかったせいか多くの人に覚えていただき、「名付け親」として嬉しい限りです。私はベタベタの実験発生生物学者であり数学とは縁遠かったのですが、なぜかMACSには初めから首を突っ込む形となり、以来、10年間にわたりSGを企画しました。「本物（トリ胚）をみて数理を考える」という共通テーマのもと、物理・数学の院生や学部生たちが数式を議論し、顕微鏡をのぞいて生（なま）のトリ胚を観る姿に心躍りました。当時ハーバード大から出た「腸ルーピング」論文は、実験生物―物理―数理の融合研究で世の中を驚愕させましたが、「ハーバードでできることが京大理学でできないはずがない」を合い言葉に、新しい挑戦に胸躍る10年間でした。 15:55-16:20 質疑応答 16:20-16:30 休憩 [16:30-18:30 第2部 2024年度 MACS 成果報告会] 16:30-17:30 各スタディグルーブ フラッシュトーク 17:30-18:30 参加学生によるポスター発表

会場: 京都大学 理学研究科セミナーハウス（建物配置図（北部構内）【10】の建物）

イベント公式言語: 日本語

The Topology, Geometry and Physics of non-Hausdorff manifolds

2025年2月19日(水) 15:00 - 17:00

O'Connell David (沖縄科学技術大学院大学 (OIST) 博士課程)

Non-Hausdorff manifolds are manifolds containing "doubled points" that cannot be separated by disjoint open sets. In this talk we will survey some mathematical and physical results surrounding these unusual spaces. As a theme, we will start with their fundamental description as a topological space, and slowly add in more and more structure of interest until we can meaningfully phrase questions of physics. On the mathematical side, we will see descriptions of non- Hausdorff manifolds as colimits of ordinary manifolds, which allows us to describe their geometric features without appealing to arbitrarily- existent partitions of unity. On the physical side, we will consider the inclusion of non-Hausdorff manifolds in a naïve 2d Lorentzian path integral for gravity, and (time permitting) explain how construct quantum fields on a non-Hausdorff background. Ultimately, we will see that these latter two arguments suggest that non-Hausdorff manifolds may be more appropriate than the standard "Trousers space" for the modelling of topology change in Lorentzian signature.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

How to define a Majorana fermion?

2025年2月20日(木) 13:00 - 14:30

藤川 和男 (東京大学 名誉教授)

It is fundamental in particle physics if the neutrino is a Dirac fermion or a Majorana fermion, and the seesaw model gives naturally a Majorana neutrino in an extension of the Standard Model. However, the commonly used chirality changing \(pseudo-C symmetry \) \(\nu^{\tilde C}_L=C\overline{\nu_L}^T\) of a chiral fermion is not defined in Lagrangian field theory. Precisely speaking, the neutrinoless double beta decay is not described by the pseudo-C symmetry. The Majorana neutrino obtained after a Bogoliubov-type canonical transformation, which is the one originally defined by Majorana using a Dirac-type fermion, describes consistently all the properties expected for the Majorana neutrino. Physical implication of this fact is briefly discussed.

会場: セミナー室 (359号室) 3階 359号室 (メイン会場) / via Zoom

イベント公式言語: 英語

Exploring the evolutionary fate of a mutualistic community using automated microbial culture system

2025年2月20日(木) 16:00 - 17:00

砂川 純也 (北海道大学 大学院生命科学院 生命科学専攻 博士課程)

Microbes are ubiquitous around the world, forming systems where they interact through competition or cooperation. Especially in the form of cooperation, exchange of essential metabolites, known as metabolic cross-feeding, plays a fundamental role in the assembly of microbial communities. An extreme case of metabolic cross-feeding is an obligate mutualism, where one organism can only grow with the help of a partner supplying metabolites (e.g., amino acid). When they face environmental stresses such as antibiotics, it is unclear whether the benefit that causes the formation of obligate ecological mutualism may benefit (or cost) the members to increases (inhibits) resistance through interactions at the evolutionary scale. Another fascinating question is whether an additional benefit (e.g., an enzyme that helps the community persistence against environmental change) will select the community to increase the resistance. Here, I will report my ongoing research progress of obligate cross-feedings involving β-lactamase and discuss the conditions where the benefit can overcome the cost of the obligate interaction. I have started to address this issue by conducting laboratory evolution experiments with an automated culture system which can automatically adjust the strength of the stress (i.e., concentration of the antibiotics), so that the focal microbes have to get evolved. I will also share my story about building this automated culture system.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Ubiquity of geometric Brascamp--Lieb data

2025年2月21日(金) 15:00 - 17:00

辻 寛 (埼玉大学 大学院理工学研究科 日本学術振興会 特別研究員 PD)

This talk is based on a joint work with Neal Bez (Nagoya university) and Anthony Gauvan (Saitama university). The Brascamp--Lieb inequality is a futher general inequality involving some data (we call it the Brascamp--Lieb datum), which has been studied in harmonic analysis and convex geometry. For instance, the Hölder inequality and the Young convolution inequality are particular cases. In this talk, we have an interest in geometric Brascamp--Lieb data, which are specific data satisfying nice properties, for which the best constant of the Brascamp--Lieb inequality is well-understood. Our goal in this talk is to show that geomtric Brascamp--Lieb data are dense in general Brascamp--Lieb data in certain sence. Our result substantially follows from the work by Garg, Gurvits, Oliveira and Wigderson.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Asymptotics in astrophysics iTHEMS workshop

2025年2月25日(火) - 28日(金)

This workshop will include overview talks of application of asymptotics and perturbation theory techniques in (wave transport or oscillation related) astrophysics and cosmology eigenvalue problems. In addition, there will be introductory talks about fundamental asymptotics and perturbation theory techniques used in theoretical physics. The purpose of this interdisciplinary workshop is to identify problems in astrophysics and related fields including, but not limited to, stellar structure and evolution, black holes and high-energy physics which can be solved using existing asymptotics and perturbation theory methods in theoretical physics problems (e.g. quantum field theory, gravity), and vice versa.

会場: 融合連携イノベーション推進棟（IIB） 8階

イベント公式言語: 英語

Quantum-Centric Supercomputing Software

2025年2月26日(水) 13:00 - 14:00

堀井 洋 (IBM Quantum シニア・テクニカル・スタッフ・メンバー)

A quantum-centric supercomputer represents the next generation of computing, combining a quantum computer with a classical supercomputer. It leverages error mitigation and error correction techniques to deliver results within practical timeframes. When fully developed, this system relies on advanced middleware to seamlessly integrate quantum circuits with classical computing resources. In this presentation, we will introduce IBM Quantum’s middleware for quantum-centric supercomputers, highlighting collaborative projects with our research partners.

会場: セミナー室 (359号室) 3階 359号室 (メイン会場) / via Zoom

イベント公式言語: 英語

Genome and Sex Chromosome Analyses of Japanese Frogs Carrying Both XY and ZW Chromosomes Within the Same Species

2025年2月27日(木) 16:00 - 17:00

桂 有加子 (京都大学 京都大学ヒト行動進化研究センター 助教)

The evolution of sex chromosomes, particularly sex chromosome turnover, is a complex and fascinating topic in genetics and evolutionary biology. Sex chromosome turnover refers to the process in which the sex chromosome system changes from XY to ZW (or vice versa), or in which sex chromosomes with different evolutionary origins emerge within the same system (e.g., from one XY system to another XY system). To study sex chromosome turnover, we focus on the Japanese frog (Glandirana rugosa), which possesses both XY and ZW sex chromosomes within the same species, and investigate the molecular mechanisms behind the turnover in the frog (Review: Hayashi et al. JB 2024). Previously, we sequenced the nuclear genome of the ZZ frog (Katsura et al. LSA 2021) and identified sex-linked genes in two populations of the XY and ZW frogs (Miura et al. Mol Ecol 2022). It has been suggested that sex chromosomes originating from at least three different chromosomal lineages have independently emerged within this species. The frogs have a total of 13 chromosomes, and in two populations (Tokai/Eastern Central Japan and Hokuriku-Tohoku/North-Western Japan), chromosome 7 has morphologically differentiated into both ZW and XY chromosomes. However, in other populations, sex chromosomes do not show any morphological differentiation. In this seminar, I introduce the background of our sex chromosome study and present the results of sequence comparisons of morphologically differentiated XY and ZW chromosomes, as well as findings from our analyses of populations, genome, and transcriptome.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

理化学研究所-奈良女子大学理学部合同 ダイバーシティ推進ワークショップ 2025

2025年3月3日(月) - 4日(火)

理化学研究所数理創造プログラム(iTHEMS)と奈良女子大学理学部は、理化学研究所ダイバーシティ推進室の後援を得て女性研究者育成事業を進めている。その一環として、奈良女子大学の学部生・大学院生19名が、理化学研究所和光キャンパスの複数の研究室を訪問し、研究内容について質疑を行うとともに、iTHEMSの研究者とともにワークショップを開催し、学生自らが発表を行う。 主催：理化学研究所数理創造プログラム、奈良女子大学理学部 プログラム： TBD

会場: via Zoom

iTHEMS Cosmology Forum 3 - (P)reheating the primordial Universe

2025年3月4日(火) - 5日(水)

榎本 成志 (横浜国立大学 理工学部 博士研究員)
John T. Giblin (Professor, Department of Physics, Kenyon College, USA)
向田 享平 (高エネルギー加速器研究機構 (KEK) 理論センター 助教)

iTHEMS Cosmology Forum Workshop is a series of short workshops, each focusing on an emerging topics in cosmology. The target audience is cosmologists, high-energy physicists and astronomers interested in learning about the subject, not just those who have already worked on the topic. The goal of the workshop is to provide working knowledge of the topic and leave dedicated time for discussions to encourage mutual interactions among participants. The third workshop is devoted to the 'reheating' phase of the early Universe. Reheating bridges the gap between the (almost) empty universe at the end of cosmic inflation and the thermal state of particles, required for Big-Bang nucleosynthesis, and the events of the hot Big-Bang model as a whole, to unfold. It is expected to proceed in different stages starting with a violent parametric resonant creation of particles, dubbed preheating, followed by a redistribution of energy leading to a thermal state. This phase potentially hosts rich phenomenology such as the formation of topoligical defects e.g. solitons, generation of gravitiational wave, and so on. Yet, the very non-linear nature of reheating makes it notoriously hard to describe analytically, and even numerical simulations struggle to follow the whole sequence of events in a given model. Reheating studies have thus yet to reach the degree of compherensiveness and universality that the understanding of cosmic inflation has achieved. This forum will consist of two events. The first, on March 4th, will be in conference format comprising scientific talks on research trends in (P)Reheating. The second, on March 5th, will be a tutorial on numerical aspects of reheating (both theory and hands-on with code) hosted by Tom Giblin of Kenyon College. The workshop will be in English. The workshops are organised by the iTHEMS Cosmology Forum working group, which is the successor of the Dark Matter Working Group at RIKEN iTHEMS. Important dates: Feb. 25th - Registration deadline March 4th - Workshop Day (Room #435-437, Main Research Building 4F) March 5th - Tutorial Day (Room #445-447, Main Research Building 4F) Invited Speakers: John T. Giblin - Kenyon College Kyohei Mukaida - KEK Seishi Enomoto - Yokohama National University Organisers: Kohei Hayashi, Nagisa Hiroshima, Derek Inman, Amaury Micheli, Ryo Namba

会場: 研究本館 4階 435-437号室 / 研究本館 4階 445-447号室

イベント公式言語: 英語

Smart heuristics of a single-celled organism

2025年3月7日(金) 14:00 - 15:30

中垣 俊之 (北海道大学 電子科学研究所 教授)

Although we rarely question how smart unicellular organisms are, it has become clear that unicellular organisms are smarter than we expected. In fact, various protozoa (unicellular eukaryotes) can take actions that are advantageous for their survival even in complex environments in the wild environments. In this talk, I will introduce some typical examples of smart behaviors in a protozoan amoeba (the plasmodium of Physarum polycephalum): (1) maze-solving, (2) formation of multi-functional transport network that mimics public transportation network among cities in Tokyo region, and so on. We will propose a mathematical model of these behaviors and extract the heuristics (simple rules of behavior) that give rise to their smartness. In general, we will discuss the future potential of research into the behavioral intelligence of protozoa.

会場: 大河内記念ホール (メイン会場) / via Zoom

イベント公式言語: 英語

Third Workshop on Density Functional Theory: Fundamentals, Developments, and Applications (DFT2025)

2025年3月25日(火) - 27日(木)

The density functional theory (DFT) is one of the powerful methods to solve quantum many-body problems, which, in principle, gives the exact energy and density of the ground state. The accuracy of DFT is, in practice, determined by the accuracy of an energy density functional (EDF) since the exact EDF is still unknown. Currently, DFT has been used in many communities, including nuclear physics, quantum chemistry, and condensed matter physics, while the fundamental study of DFT, such as the first principle derivations of an accurate EDF and methods to calculate many observables from obtained densities and excited states, is still ongoing. However, there has been little opportunity to have interdisciplinary communication. On December 2022, we had the first workshop on this series (DFT2022) at Yukawa Institute for Theoretical Physics, Kyoto University, and several interdisciplinary discussions and collaborations were started. On February 2024, we had the second workshop on this series (DFT2024) at RIKEN Kobe Campus, and more stimulated discussion occured. To keep and extend collaborations, we organize the third workshop. Since the third workshop, we extend the scope of the workshop to the development and application of DFT as well. In this workshop, the current status and issues of each discipline will be shared towards solving these problems by meeting together among researchers in mathematics, nuclear physics, quantum chemistry, and condensed matter physics. This workshop mainly comprises lectures/seminars on cutting-edge topics and discussion, while sessions composed of contributed talks are also planned.

会場: 融合連携イノベーション推進棟（IIB） 8階 / via Zoom

イベント公式言語: 英語

Stability of nonsingular black holes

2025年3月27日(木) 15:00 - 16:30

辻川 信二 (早稲田大学 理工学術院 先進理工学研究科 物理学及応用物理学専攻 辻川研究室 教授)

We show that nonsingular black holes (BHs) realized in nonlinear electrodynamics are always prone to Laplacian instability around the center because of a negative squared sound speed in the angular direction. This is the case for both electric and magnetic BHs, where the instability of one of the vector-field perturbations leads to enhancing a dynamical gravitational perturbation in the even-parity sector. Thus, the background regular metric is no longer maintained in a steady state. We also generalize our analysis to the case in which a scalar field is present besides the U(1) gauge field and find no explicit examples of linearly stable nonsingular BHs. Our results suggest that the construction of regular BHs without instabilities is generally challenging within the scheme of classical field theories.

会場: セミナー室 (359号室) (メイン会場) / via Zoom

イベント公式言語: 英語