RIKEN Interdisciplinary Theoretical and
Mathematical Sciences Program
理化学研究所 数理創造プログラム

セミナー 本日開催 iTHEMS生物学セミナー

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

その他

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

その他

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: 研究本館 セミナー室（359号室）

イベント公式言語: 英語

セミナー iTHEMS生物学セミナー

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

セミナー iTHEMSセミナー

Gauge-equivariant neural networks as preconditioners in lattice QCD

2023年4月6日(木) 13:30 - 15:00

Prof. Tilo Wettig (Professor, Universität Regensburg, Germany)

We demonstrate that a state-of-the-art multi-grid preconditioner can be learned efficiently by gauge-equivariant neural networks. We show that the models require minimal re-training on different gauge configurations of the same gauge ensemble and to a large extent remain efficient under modest modifications of ensemble parameters. We also demonstrate that important paradigms such as communication avoidance are straightforward to implement in this framework.

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

コロキウム

Emergence of Extreme Universe from Quantum Information

2023年4月17日(月) 16:00 - 17:30

高柳 匡 (京都大学 基礎物理学研究所 教授)

Recently, a new interpretation of gravitational spacetime in terms of quantum entanglement has been obtained. The idea of holography in string theory provides a simple geometric computation of entanglement entropy. This generalizes the well-known Bekenstein-Hawking formula of black hole entropy and strongly suggests that a gravitational spacetime consists of many qubits with quantum entanglement. Also a new progress on black hole information problem has been made recently by applying this idea. I will explain these developments in this colloquium.

会場: via Zoom

イベント公式言語: 英語

セミナー ABBL-iTHEMSジョイントアストロセミナー

Towards EeV Neutrino Astronomy with GRAND

2023年4月18日(火) 14:00 - 15:00

クミコ・コテラ (Associate Professor, Institute of Astrophysics, France)

We are living exciting times: we are now able to probe the most violent events of the Universe with diverse messengers (cosmic rays, neutrinos, photons and gravitational waves). One challenge to complete the multi-messenger picture resides in the highest energies, as no ultra-high energy neutrinos have been observed yet. This challenge could be undertaken by the GRAND (Giant Radio Array for Neutrino Detection) project, which aims at detecting ultra-high energy particles, with a colossal array of 200'000 antennas over 200'000 km2, split into ~20 sub-arrays of ~10'000 km2 deployed worldwide. In this talk, we will present preliminary designs and simulation results, plans for the ongoing, staged approach to construction, and the rich research program made possible by the proposed sensitivity and angular resolution.

会場: コモンルーム (246-248号室) / via Zoom

イベント公式言語: 英語

セミナー ABBL-iTHEMSジョイントアストロセミナー

X-ray study on the synchrotron emission in Kepler's SNR

2023年5月19日(金) 14:00 - 15:00

Dr. Vincenzo Sapienza (東京大学 大学院理学系研究科 物理学専攻 博士課程)

Synchrotron X-ray emission in young supernova remnants (SNRs) is a powerful diagnostic tool to study the population of high energy electrons accelerated at the shock front. We performed a spatially resolved spectral analysis of the young Kepler's SNR, where we identify two different regimes of particle acceleration. In the north, where the shock interacts with a dense circumstellar medium (CSM), we found a more efficient acceleration than in the south, where the shock velocity is higher and there are no signs of shock interaction with dense CSM. We also studied the temporal evolution of the synchrotron flux, from 2006 to 2014. A number of regions show a steady synchrotron flux and equal cooling and acceleration times. However, we found some regions where we measured a significant decrease in flux from 2006 to 2014. Our results display a coherent picture of the different regimes of electron acceleration observed in Kepler's SNR. Also If I will have time during the seminar it will be nice to present also some preliminary results I will have in the SN 1987A project.

会場: コモンルーム (246-248号室) / via Zoom

イベント公式言語: 英語

セミナー 理論物理学セミナー

Spectral correlations and scrambling dynamics in Sachdev-Ye-Kitaev type models

2023年5月30日(火) 13:30 - 15:00

手塚 真樹 (京都大学 大学院理学研究科 物理学・宇宙物理学専攻 助教)

Note: Due to unexpected trouble, we have made the decision to postpone the seminar scheduled for February 21 to May 30. Sorry for the trouble. Abstract: The Sachdev-Ye-Kitaev (SYK) model, proposed in 2015, is a quantum mechanical model of N Majorana or complex fermions with all-to-all random four-body interactions. The model has attracted significant attention over the years due to its features such as the existence of the large-N solution with maximally chaotic behavior at low temperatures and holographic correspondence to low-dimensional gravity. The sparse version of the SYK model reproduces essential features of the original model for reduced numbers of disorder parameters. We recently proposed [1] a further simplification, where we set the nonzero couplings to be +1 or -1 rather than sampling from a continuous distribution such as Gaussian. This binary-coupling model exhibits strong correlations in the spectrum, as observed in the spectral form factor, more efficiently in terms of the number of nonzero terms than in the Gaussian distribution case. We also discuss the scrambling dynamics with the binary-coupling sparse SYK model, comparing the model with the original model as well as the SYK model with random two-body terms [2], where the localization of the many-body eigenstates in the Fock space has been quantitatively studied [3,4].

会場: コモンルーム (246-248号室) / via Zoom

イベント公式言語: 英語

スクール iTHEMS共催

g-RIPS-Sendai 2023

2023年6月19日(月) - 8月8日(火)

東北大学材料科学高等研究所（AIMR）では、2018年よりg-RIPS (Graduate-level Research in Industrial Projects for Students)-Sendai プログラムを開催しています。本プログラムはパートナー企業から提供された課題に、アメリカと国内からの参加者がグループとなって集中的に取り組み、解決に至る道筋を学ぶ国際インターンシッププログラムのひとつです。本年のg-RIPS-Sendai 2023の詳細は、関連リンクより本プログラムのウェブサイトをご覧ください。 主催: 東北大学・数理科学連携研究センター (RACMaS) 東北大学・知の創出センター (TFC) 東北大学・材料科学高等研究所 (AIMR) 共催: 理化学研究所・数理創造プログラム (iTHEMS) Institute for Pure & Applied Mathematics, UCLA

会場: 東北大学 片平キャンパス 材料科学高等研究所（AIMR）

ワークショップ iTHEMS協賛

6th Workshop on Virus Dynamics

2023年7月4日(火) - 6日(木)

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)
岩見 真吾 (名古屋大学 大学院理学研究科 教授)

The Workshop on Virus Dynamics is an international meeting held every 2 years. It brings virologists, immunologists, and microbiologists together with mathematical and computational modellers, bioinformaticians, bioengineers, virophysicists, and systems biologists to discuss current approaches and challenges in modelling and analyzing different aspects of virus and immune system dynamics, and associated vaccines and therapeutics. This 6th version of the workshop builds on the success of previous ones held in Frankfurt (2013), Toronto (2015), Heidelberg (2017), Paris (2019) and virtually (2021). It is supported by the Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) program at RIKEN, by Nagoya University, and by the Japan Science and Technology Agency. Up-to-date information and registration is available via the website. The workshop is for in-person participation only (no virtual or hybrid option).

会場: 名古屋大学 野依記念学術交流館 東山キャンパス

イベント公式言語: 英語