Asymmetric enzyme kinetics of F1-ATPase resulted from asymmetric allosterism

2023年3月30日(木) 16:00 - 17:00

中山 洋平 (東北大学 大学院工学研究科 応用物理学専攻 助教)

Bio-molecular machines play various roles in cells where thermal fluctuation is dominant. Since artificial molecular machines are far behind bio-molecular machines for the present, we should begin with understanding how bio-molecular machines are designed to play their roles. We examine the motion of a bio-molecular machine, F1-ATPase, in single molecule experiments. In particular, we focus on the operation of F1-ATPase as ATP synthase in addition to as molecular motor. In this seminar, I talk about the enzyme kinetics, dependence of reaction rate on substrate concentration, of F1-ATPase in ATP synthesis. The experimental result shows that the enzyme kinetics of F1-ATPase in ATP synthesis exhibits weaker dependence on substrate concentration than the ordinary Michaelis-Menten kinetics, whereas that in ATP hydrolysis follows Michaelis-Menten kinetics. Therefore, the enzyme kinetics of F1-ATPase turned out to be asymmetric between ATP synthesis and hydrolysis. We analyzed this asymmetry based on a potential switching model, totally asymmetric allosteric model, whose characteristic is asymmetry in angular dependence of binding rates of substrates. It was shown that the totally asymmetric allosteric model may reproduce the experimental results, where the asymmetry of binding rates is essential. We also discuss physiological roles that the asymmetry of enzyme kinetics may play.

会場: via Zoom

イベント公式言語: 英語

First Chalk

2023年3月29日(水) 16:30 - 17:00

The occasion to celebrate the launch of the new seminar room will take place after iTHEMS NOW & NEXT.

会場: セミナー室 (359号室)

イベント公式言語: 英語

iTHEMS NOW & NEXT FY2022

2023年3月29日(水) 9:30 - 15:45

井上 瑛二 (数理創造プログラム 基礎科学特別研究員)
ジェフリ・フォーセット (数理創造プログラム 上級研究員)
田屋 英俊 (数理創造プログラム 基礎科学特別研究員)
大下 翔誉 (数理創造プログラム 基礎科学特別研究員)
土井 琢身 (数理創造プログラム 専任研究員)

Program: 9:30-10:00 Keynote Talk by Eiji Inoue 10:00-10:30 Keynote Talk by Jeffrey Fawcett 10:35-11:05 Keynote Talk by Hidetoshi Taya 11:05-11:35 Keynote Talk by Naritaka Ohshita 11:40-12:10 Keynote Talk by Takumi Doi 12:30-13:10 Lunch Time Session on Research Ethics 13:15-13:45 Working Group Report 13:45-14:20 Study Group Report 14:30-15:30 Panel Discussion on future of iTHEMS 15:30-15:45 Concluding Remarks by the Director

会場: via Zoom

イベント公式言語: 英語

Warming reduces the density-dependent divergence in emergence time for two competing parasitoid species

2023年3月23日(木) 16:00 - 17:00

津田 みどり (九州大学 大学院農学研究院 資源生物科学部門 農業生物資源学 准教授)

Climate change is expected to directly affect ectothermic species through their sensitivity to temperature, with cascading effects on populations and communities. Here we experimentally tested predictions from two non-exclusive hypotheses concerning the impacts of elevated temperature (+2°C) on interactions between a single host species (the azuki bean beetle) and two species of parasitoid wasps. We hypothesized that increasing temperature shortens the time that the host is vulnerable to parasitoid attack. This change in available resource should heighten intra- and interspecific competition among parasitoids, which could induce divergence in emergence times. We found that intraspecific competition of both parasitoid species was more intense than interspecific competition irrespective of temperature. The difference (d) in the emergence times of the two parasitoid species increased with the density of each parasitoid but decreased at the elevated temperature. Both parasitoids emerged sooner at the elevated temperature and experienced a reduction in body size. Thus, high levels of intraspecific competition (along with the consequent reduction in body size) may have attenuated the intensity of interspecific competition at the elevated temperature despite a reduction in the differentiation of emergence times.

会場: via Zoom

イベント公式言語: 英語

Lab-Theory Standing Talks #1

2023年3月16日(木) 13:00 - 13:30

大岡 英史 (理化学研究所 環境資源科学研究センター (CSRS) 生体機能触媒研究チーム 研究員)

会場: 研究本館 3階 共有スペース

イベント公式言語: 英語

Towards S-matrix theory of unstable particles

2023年3月15日(水) 13:30 - 15:00

青木 勝輝 (京都大学 基礎物理学研究所 基研特任助教)

The S-matrix is one of the central objects in quantum field theory and gains renewed interest recently to understand the possible structures of low-energy effective field theories and quantum gravity. However, most of the particles have finite decay widths and thus do not appear in asymptotic states. Therefore, the standard S-matrix arguments may not be directly applied to scatterings of such unstable particles and we need to formulate “the S-matrix theory of unstable particles” to properly understand the availability of the S-matrix arguments in realistic systems. In this talk, I will talk about the first steps towards this goal. In particular, I will discuss non-perturbative consequences of unitarity in a scattering amplitude of unstable particles and its analytic properties.

会場: コモンルーム 246-248号室 とZoomのハイブリッド開催

イベント公式言語: 英語

Neutrinos from the big bang: probing cosmic gravitational inhomogeneities & magnetic fields in the early universe

2023年3月13日(月) 13:30 - 15:00

ゴードン・ベイム (Professor Emeritus, University of Illinois, USA)

Primordial neutrinos from the Big Bang are about 100 times more prevalent than solar neutrinos, and at least two-thirds of them are now non-relativistic. These relic neutrinos, which have never been detected, decoupled in the early universe predominantly in helicity eigenstates. As I will discuss, their subsequent propagation through gravitational inhomogeneities and even background gravitational radiation, as well as cosmic and galactic magnetic fields partially flips their helicities, and can produce noticeable effects in their eventual detection. I will briefly mention future detection of relic neutrinos.

会場: コモンルーム (246-248号室) (メイン会場) / via Zoom

イベント公式言語: 英語

Cosmic magnetism and its effects on the observed properties of ultra high-energy cosmic rays

2023年3月10日(金) 14:00 - 15:00

Dr. Ellis Owen (大阪大学 大学院理学研究科 宇宙地球科学専攻 宇宙進化グループ JSPS特別研究員)

Ultra high-energy (UHE) cosmic rays (CRs) from distant sources interact with intergalactic radiation fields, leading to their spallation and attenuation through photo-hadronic processes. Their deflection and diffusion in large scale intergalactic magnetic fields (IGMFs), in particular those associated with Mpc-scale structures, alter the cumulative cooling and interactions of a CR ensemble to modify their spectral shape and composition observed on Earth. In this talk, I will demonstrate the extent to which IGMFs can affect observed UHE CRs, and show that source population models are degenerate with IGMF properties. Interpretation of observations, including the endorsement or rejection of any particular UHE CR source classes, needs careful consideration of the structural properties and evolution of IGMFs. Future observations providing tighter constraints on IGMF properties will significantly improve confidence in assessing UHE CR sources and their intrinsic CR production properties.

会場: via Zoom / コモンルーム (246-248号室)

イベント公式言語: 英語

Feynman’s proof of integrability of Calogero system from a modern point of view

2023年3月10日(金) 10:00 - 11:30

Dr. Yehao Zhou (東京大学 カブリ数物連携宇宙研究機構 (Kavli IPMU) 特任研究員)

In his last year of life Feynman was interested in integrable system, and in his study of Calogero models he came up with his own proof of the commutativity of integrals of motions of these models, which remains unpublished until it was transcribed by Polychronakos in 2018. His idea is to organize integrals of motions of a Calogero model into a generating function of differential operators which look like a correlation function in a certain free theory, then he showed that the generating function of differential operators commute for all spectral values, which leads to a proof of commutativity of integrals of motions. He commented on his proof “I learn nothing, no real clue as to why all this works, and what it means”. Recently in a joint work with Davide Gaiotto and Miroslav Rapcek we identify Feynman’s generating function as the correlation function of Miura operators in a W-algebra of type A, and in the rational and trigonometric cases we show that they equal to certain elements in the Dunkl representation of corresponding spherical Cherednik algebras in type A, which make the commutativity self-evident. This progress is a byproduct of a project in the study of M2-M5 brane junction in the M-theory.

会場: コモンルーム (246-248号室) / via Zoom

イベント公式言語: 英語

Reproductive interference can affect trait diversity of closely related animal species

2023年3月9日(木) 16:00 - 17:00

森田 慶一 (総合研究⼤学院⼤学 先導科学研究科 生命共生体進化学専攻 博士課程)

Previous theoretical studies have considered that evolution driven by resource competition is important for the creation and maintenance of biodiversity. Recently, reproductive interference caused by misrecognition of sexual traits such as calling between closely related species has been increasingly important for the creation and maintenance of diversity, but the impact of reproductive interference on trait diversity between closely related species remains unresolved. In this study, we combined population dynamics model with reproductive interference in two closely related species with an evolutionary model of traits related to reproduction to examine the impact of reproductive interference on the evolutionary consequences of reproductive traits in the two closely related species. The model assumed a trade-off in which reproductive interference weakens as reproductive traits diverge between the two species, but predation pressure increases as the reproductive traits diverge from their optimum traits in their habitat. For simplicity, we assumed that only one species evolves. Our model analysis revealed that convergence and divergence of traits of two closely related species occurs depending on initial trait divergence. Also, under the parameter condition where trait convergence occurs, large mutation makes trait divergence possible. Our model will provide a new framework for understanding evolutionary dynamics in ecological communities containing closely related species.

会場: via Zoom

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

2023年3月7日(火) 13:30 - 13:00

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17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、学生自らが研究発表を行う。 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： 3月7日（火） 13:30-14:00 開会の挨拶 初田哲男 (iTHEMS) 14:00-15:30 川上 恵里加 研究室 (RQC)（S51, 物質科学研究棟） 15:30-17:00 侯 召民 研究室 (CSRS)（S51, 物質科学研究棟） 17:00-18:30 数理創造プログラム (iTHEMS)（C01, 研究本館） 18:30-21:00 奈良女子大学学生の研究発表会（C01, 研究本館） 3月8日（水） 9:00-10:30 仁科センターRIBF施設 (RNC)（E01, 仁科RIBF棟） 10:30-12:00 宮脇 敦史 研究室 (CBS) （C51, 脳科学中央研究棟） 12:00-13:00 昼食（C61, 総合支援施設） 13:00 閉会

Topological Kondo superconductors

2023年3月2日(木) 17:00 - 18:15

Dr. Yung-Yeh Chang (Postdoctoral Researcher, National Center for Theoretical Sciences & National Chiao Tung University, Taiwan)

Spin-triplet p-wave superconductors are promising candidates for topological superconductors. They have been proposed in various heterostructures where a material with strong spin-orbit interaction is coupled to a conventional s-wave superconductor by proximity effect. However, topological superconductors existing in nature and driven purely by strong electron correlations are yet to be studied. Here we propose a realization of such a system in a class of Kondo lattice materials in the absence of proximity effect. Therein, the odd-parity Kondo hybridization mediates ferromagnetic spin-spin coupling and leads to spin-triplet resonant-valence-bond (t-RVB) pairing between local moments. Spin-triplet p±p’ wave topological superconductivity is reached when Kondo effect co-exists with t-RVB [1]. We identify the topological nature by the non-trivial topological invariant and the Majorana zero modes at edges. Our results on the superconducting transition temperature, Kondo coherent scale, and onset temperature of Kondo hybridization not only qualitatively but also quantitatively agree with the observations for UTe2, a U-based ferromagnetic heavy-electron superconductor. *This work is supported by the National Science and Technology Council, Taiwan. Field: condensed matter physics Keywords: strongly correlated systems, topological superconductor, Kondo effect, resonant valence bond, heavy-fermion compounds

会場: via Webex

イベント公式言語: 英語

How to sit Maxwell and Higgs on the boundary of AdS

2023年2月28日(火) 13:30 - 15:00

Dr. Matteo Baggioli (Associate Professor, School of Physics and Astronomy, Shanghai Jiao Tong University, China)

Within the holographic correspondence, boundary conditions play a fundamental role in determining the nature of the dual field theory. In this talk, I will show how to exploit mixed boundary conditions to obtain dynamical electromagnetism in the boundary theory. This is necessary to apply AdS-CFT to many real-world applications, e.g., magnetohydrodynamics, plasma physics, superconductors, etc. where dynamical gauge fields and Coulomb interactions are fundamental. As a proof of concept, I will show two emblematic cases. First, I will prove that the results from the 4-dimensional Einstein-Maxwell bulk theory with these deformed boundary conditions are in perfect agreement with relativistic magneto-hydrodynamics in 2+1 dimensions. Second, I will discuss the collective excitations of a bona-fide holographic superconductor and prove the existence of the Anderson-Higgs mechanism therein.

会場: 中央大学後楽園キャンパス 6号館 6209教室 (メイン会場) / via Zoom

イベント公式言語: 英語

Interdisciplinary Science Conference in Okinawa (ISCO 2023)

2023年2月27日(月) - 3月3日(金)

The scientific method of studying the natural world has persisted over the centuries. The key to its longevity and progression lies in sharing and building upon accumulated knowledge. Physics, which explores the origin of the universe and matter; biology, which studies living organisms, and their functions and evolution; and medicine, which explores health based on the structure and function of living organisms: all have made enormous advancements that impact all aspects of our lives. As the scientific study progresses, however, additional challenges have arisen which are increasingly difficult to solve. Many of the challenges that humanity faces are in achieving sustainable development. These include environmental changes due to climate change, food crises caused by the gap between population growth and food production, and pandemics caused by the spreading of resistant bacteria and viruses. To rise to these new challenges, it is important to reassess the issues from a broader perspective: to combine the knowledge and methods of different scientific fields and to look for new approaches that can bridge the boundaries and work across multiple fields The purpose of ISCO 2023 is to bring together leading researchers in their respective fields, explore methods for solving issues through the fusion of different fields, and form a new network of researchers. The workshop will bring together speakers from Japan and abroad in the fields of space science, particle and nuclear physics, quantum computing, life sciences, and medicine to discuss the challenges they face and the latest advancements in their respective fields. We call for presentations from fields related to those subjects mentioned above and on the sustainable development of humankind. In addition, we plan to hold a poster session to facilitate a wide range of discussions. We hope that the knowledge gained at this workshop will lead to the creation of new research fields that will not only advance basic science but will also help solve the various new challenges that humanity faces.

会場: OIST Auditorium / via Zoom

イベント公式言語: 英語

Algebra of symmetry in BF-like models in 3d and 4d

2023年2月22日(水) 14:00 - 15:30

Dr. Christophe Goeller (Humboldt Fellow, Ludwig-Maximilians-Universität München, Germany)

In this talk, I will discuss the construction of the boundary symmetry algebra for BF-like theories in 3D and 4D. In the 3D case, the theory corresponds to (an extension of) 3D gravity allowing for a source of curvature and torsion. I will show how the study of the current algebra and its associated Sugawara construction allows for two notions of quadratic charges (the usual diffeomorphism and its "dual") independently of boundary conditions. I will discuss their resulting algebra and its relation with the usual construction of the asymptotic boundary algebra. In the 4D case, a similar yet fundamentally different construction is possible, similarly resulting in multiple quadratic charges. I will discuss their constructions and their possible relations to 4D gravity.

会場: コモンルーム 246-248号室 とZoomのハイブリッド開催

イベント公式言語: 英語

The Electron-Ion Collider: the Ultimate Electron Microscope

2023年2月20日(月) 15:00 - 16:30

ゴードン・ベイム (Professor Emeritus, University of Illinois, USA)

How does the nucleon get its mass? Certainly not from the Higgs -- the rest masses of the quarks it contains add up to only one percent of the nucleon mass. Rather the remaining 99% comes from the zero-point energy of the quarks, antiquarks and gluons localized in the nucleon. How do nuclei differ from being a simple collection of nucleons? How are the gluons, for example, distributed in nuclei? Do they stick out, or are they clumped towards the center of the nucleon? Gluons, like dark matter unseen but playing the crucial role in gluing matter together, are strongly interacting. Do such gluons form new emergent quantum states in nuclei, as in condensed matter physics? And how is the spin of the proton -- the key to NMR imaging -- put together from the spin and orbital motion of the quarks and gluons in the proton?

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

階層をつなぐ科学：宇宙から生命まで

2023年2月20日(月) 10:00 - 16:45

横倉 祐貴 (数理創造プログラム 上級研究員)
伊藤 悦子 (数理創造プログラム 上級研究員)
カトゥリン・ボシゥメン (数理創造プログラム 副プログラムディレクター)

現代科学は、それぞれの研究分野が成熟して高度化・深化するにつれて、分野全体からみると細分化しすぎてしまっているという問題点も同時に生み出している。一方で、個々の研究テーマに目を向けると、宇宙創生と素粒子理論、中性子星と原子核理論、宇宙の大規模構造と銀河・星・惑星形成、幅広いスケールにわたる乱流現象、生命と非平衡現象、などのように異なる階層構造を跨ぐ研究も進展し、物理現象を統合的に捉える努力が研究者単位で広がっている。「階層」という言葉は、理論の階層、異なる原理や視点という解釈もできるだろう。 そこで今回のTJR研究会では、関連する講師を外部から招待し、それぞれの研究分野においてどのように階層構造を連結しようと努力しているかについて焦点をおいて講演をしてもらい、研究の視野を広げて新たな視点を今後の研究に取り入れてもらうことを狙いとする。もちろん若い世代に分野横断型の研究テーマを知らしめ、インスピレーションを与えて鼓舞する目的もある。

会場: 大阪大学 豊中キャンパス 南部陽一郎ホール / via Zoom

Coherent sheaves, quivers, and quantum groups

2023年2月17日(金) 14:00 - 16:00

Dr. Gufang Zhao (Senior Lecturer, University of Melbourne, Australia)

This talk aims to illustrate symmetries in geometry. The first half surveys a few examples of parametrizing coherent sheaves on a variety and how quantum groups control the symmetry of parametrization space. The second half aims to illustrate some special cases when the variety is a local toric 3-Calabi-Yau.

会場: コモンルーム 246-248号室 とZoomのハイブリッド開催

イベント公式言語: 英語

String theory, N=4 SYM and Riemann hypothesis

2023年2月16日(木) 14:00 - 16:10

本多 正純 (京都大学 基礎物理学研究所 助教)

We discuss new relations among string theory, four-dimensional N=4 supersymmetric Yang-Mills theory (SYM) and the Riemann hypothesis. It is known that the Riemann hypothesis is equivalent to an inequality for the sum of divisors function σ(n). Based on previous results in literature, we focus on the fact that σ(n) appears in a problem of counting supersymmetric states in the N=4 SYM with SU(3) gauge group: the Schur limit of the superconformal index plays a role of a generating function of σ(n). Then assuming the Riemann hypothesis gives bounds on information on the 1/8-BPS states in the N=4 SYM. The AdS/CFT correspondence further connects the Riemann hypothesis to the type IIB superstring theory on AdS5×S5. In particular, the Riemann hypothesis implies a miraculous cancellation among Kaluza-Klein modes of the supergravity multiplet and D3-branes wrapping supersymmetric cycles in the string theory. We also discuss possibilities to gain new insights on the Riemann hypothesis from the physics side. This talk is based on a collaboration with Takuya Yoda (arXiv:220317091).

会場: コモンルーム 246-248号室 とZoomのハイブリッド開催

イベント公式言語: 英語

Quantum groups and cohomology theories

2023年2月15日(水) 14:00 - 16:00

Dr. Yaping Yang (Senior Lecturer, University of Melbourne, Australia)

In the first half of my talk, I will review quantum groups at roots of unity and their representation theory. In the second half, I will explain a construction of new quantum groups using cohomology theories from topology. The construction uses the so-called cohomological Hall algebra associated to a quiver and an oriented cohomology theory. In examples, we obtain the Yangian, quantum loop algebra and elliptic quantum group, when the cohomology theories are the cohomology, K-theory, and elliptic cohomology respectively.

会場: コモンルーム 246-248号室 とZoomのハイブリッド開催

イベント公式言語: 英語