ニュース
202件のニュース / 2022年

20220518
セミナーレポートiTHEMS Math Seminar by Dr. Taketo Sano on May 13, 2022
In May 13, there was a math seminar by Taketo Sano. He gave an introductory talk on category theory. Reported by Keita Mikami

20220509
プレスリリース巨視的な遷移における速度限界の発見 －連続の式に基づく統一的アプローチ－
理化学研究所（理研）開拓研究本部非平衡統計力学理研白眉研究チームの濱崎立資理研白眉研究チームリーダー（数理創造プログラム上級研究員）は、「巨視的な遷移」を伴うような物理的過程において有用となる「速度限界」、すなわち遷移速度に関する不等式を新たに発見しました。 本研究成果は、量子多体系の熱平衡化の時間スケールなどをはじめとする非平衡統計力学へ示唆を与えると同時に、巨視的な量子系の制御など、近年重要となっている量子技術の基礎的な理解に貢献することが期待できます。 続きは関連リンクをご覧ください。

20220509
プレスリリーストンガ海底火山噴火のラム波を鮮明に可視化 －ひまわり8号が捉えた波の全貌－
理化学研究所（理研）計算科学研究センターデータ同化研究チームの三好建正チームリーダー（開拓研究本部三好予測科学研究室主任研究員、数理創造プログラム副プログラムディレクター）、大塚成徳研究員（開拓研究本部三好予測科学研究室研究員、数理創造プログラム研究員）の研究チームは、気象衛星ひまわり8号の画像を用いて、2022年1月に発生したトンガの海底火山噴火に伴う音波の一種である「ラム波」を鮮明に可視化する手法を独自に開発しました。さらに、この画像からラム波を自動抽出する手法を開発し、到達時刻分布や地上気圧観測との関係を明らかにしました。 本研究成果は、火山噴火などに伴う大気波動やそれに伴う潮位変動の科学的理解と実況監視、観測データと大気・海洋の大規模計算との融合によるシミュレーションの高度化や将来的な予測手法の開発に貢献すると期待できます。 続きは関連リンクをご覧ください。

20220505
今週の論文Week 2, May 2022
Title: High energy emission component, population, and contribution to the extragalactic gammaray background of gammaray emitting radio galaxies Author: Yasushi Fukazawa, Hiroto Matake, Taishu Kayanoki, Yoshiyuki Inoue, Justin Finke arXiv: http://arxiv.org/abs/2204.14019v1 Title: The $a$points of the Riemann zetafunction and the functional equation Author: Athanasios Sourmelidis, Jörn Steuding, Ade Irma Suriajaya arXiv: http://arxiv.org/abs/2204.13887v1 Title: Speed Limits for Macroscopic Transitions Author: Ryusuke Hamazaki Journal Reference: PRX Quantum 3, 020319 (2022) doi: https://doi.org/10.1103/PRXQuantum.3.020319 arXiv: http://arxiv.org/abs/2110.09716v3

20220430
セミナーレポートiTHEMS Biology Seminar by Mr. Daiki Kumakura on April 28, 2022
On April 28th, I talked about the Asgard archaea and the theory of intracellular symbiosis and discussed the mathematical modeling of the symbiosis hypothesis. First, I gave a brief of the classification of the organism as a fivekingdom system and threedomain system. Next, I talked about Asgard archaea, a group of archaea that has received much attention recently. Finally, I discussed the culture of Asgard archaea and the new theory of intracellular symbiosis that has developed as a result. In my presentation, I prepared the idea of mathematical modeling for the new theory. Audience members gave a variety of opinions on this model. In particular, I discussed points where the evolutionary model should be added, whether deterministic or stochastic dominance contributed, and why symbiosis was possible only in two specific species although a variety of symbiotic relationships were possible. I had a meaningful time exchanging opinions and having discussions with various researchers. Thank you so much. Reported by Daiki Kumakura

20220428
受賞情報Takemasa Miyoshi and Yuji Sugita received 2022 MEXT Commendation for Science and Technology
Takemasa Miyoshi (RCCS Team Leader/ iTHEMS Deputy Director) received "2022 MEXT Commendation for Science and Technology" for "Study on Big Data Assimilation to Innovate Numerical Weather Forecasting". Congratulations! Yuji Sugita (CPR Chief Scientist/ iTHEMS Senior Research Scientist) received "2022 MEXT Commendation for Science and Technology" for "Theoretical Study on Dynamic Structure of Biomolecules in the Intracellular Environment". Congratulations!

20220428
セミナーレポートiTHEMS Colloquium by Dr. HongYan Shih on April 22, 2022
On April 22 (Fri), we had the first iTHEMS colloquium of FY2022 by inviting HongYan Shih from Academia Sinica, Taiwan. After reviewing the turbulent phenomena in various area of science, she discussed how the turbulence occurs by increasing the flow velocity and how one can develop an effective theory to describe the critical region of laminarturbulent transition. Then she discussed a remarkable mathematical relation between the effective theory with the predatorprey dynamics in ecology and showed a characteristic super exponential scaling law. The topic was an ideal subject for the interdisciplinary talk, and there were many questions from the researchers with different scientific backgrounds.

20220428
今週の論文Week 5, April 2022
Title: Visualizing Lamb Waves From a Volcanic Eruption Using Meteorological Satellite Himawari8 Author: Shigenori Otsuka Journal Reference: Geophysical Research Letters, 49, e2022GL098324 (2022) doi: https://doi.org/10.1029/2022GL098324

20220428
セミナーレポートIntroduction to Topological Insulators by Dr. Tomoki Ozawa on April, 2022
In this lecture series, Professor Ozawa gave an introduction to topological insulators which are materials whose wavefunctions show nontrivial topological structures in momentum space. In the first two lectures, he introduced the socalled SuSchriefferHeeger model and the bulkedge correspondence which links edge states with winding number of certain operator in the Hamitonian. Such correspondence has its origin in mathematics called Toeplitz Index theorem which is a special case of AtiyahSinger index theorem. In the last two lectures, Chern insulators and quantum metrics are introduced. Eigenvectors of the Hamiltonian define a map from the momentum space (typically a torus) to a complex projective space. The pullback FubiniStudy metric (and standard Kahler form) defines the socalled quantum metric (and Berry curvature) on the momentum space. Using ChernWeil theory, Chern classes/characters are then defined. Chern classes which are originally notions from differential geometry/topology play an important role in topological insulators. A necessary and sufficient condition is also given when the above mentioned map is an immersion and realises momentum space as a Kahler submanifold of the projective space. Reported by Yalong Cao

20220425
セミナーレポートiTHEMS Math Seminar by Dr. Cédric Ho Thanh on April 22, 2022
On April 22, there was a math seminar by Dr. Cédric Ho Thanh. In the first half, he explained the recurrence theorems for the topological Markov chain. In the second half, he explained the sketch of the proof. Reported by Keita Mikami

20220425
リサーチニュースRIKEN Research: Quantum computing and deep learning could help solve the mysteries of quantum gravity
RIKEN physicists have put quantum computing and deep learning through their paces and found that they are powerful tools for gleaning insights into new theories of quantum gravity [1]. They could thus help solve one of the most formidable challenges in modern physics—developing a theory of gravity that jives with quantum physics. When Einstein nutted out his theory of general relativity in 1915, his only tools were pen and paper. The same was true of the pioneers of quantum theory. But the next major breakthrough in theoretical physics could be made with help from emerging technologies such as quantum computers and machine learning, Enrico Rinaldi of RIKEN Theoretical Quantum Physics Laboratory thinks. “I believe these technologies are poised to transform the way we do theoretical physics,” he says. To read more, please visit the related link.

20220425
ホットトピックiTHEMS x academist online event was held on April 24, 2022
As the alternative for the lectures at RIKEN’s annual open house, iTHEMS held another online lecture event for the general public with the help of Academist Inc., on April 24th, 2022. This year, the lectures were Masaki Taniguchi, Hidetoshi Taya, Akira Harada, Yingying and Euki Yazaki, who all gave splendid public lectures accessible even to juniorhigh school students. Each lecturer also served as a commentator to another lecture, asking questions on behalf of the audience. During the lunch break, Program Director Hatsuda showed the offices of iTHEMS and around. The event was moderated by Ms. Michibayashi from Academist; Her facilitation with a wit kept the event lively. At one time during the event, more than two hundred audiences participated.

20220425
セミナーレポートABBLiTHEMS Joint Astro Seminar by Dr. Masanori Iwamoto on April 22, 2022
Dr. Masahiro Iwamoto gave a presentation on his recent threedimensional (3D) particleincell (PIC) simulation of relativistic shocks and application of the results of the 3DPIC simulations to astrophysical phenomena. For example, the origin of fast radio bursts (FRBs; Lorimer et al. 2007) is one of the unsolved problems in astrophysics. Many observations of FRBs indicate that FRBs must be coherent emission in the sense that coherently moving electrons radiate electromagnetic waves. In relativistic shocks, it is well known that coherent electromagnetic waves are excited by synchrotron maser instability (SMI) in the shock transition (Hoshino & Arons 1991). The SMI is also known as the emission mechanism of coherent radio sources such as auroral kilometric radiation at Earth and Jovian decametric radiation. Recently, some models of fast radio burst based on the coherent emission from relativistic shock via the SMI have been proposed (e.g., Lyubarsky 2014; Beloborodov 2017; Plotnikov & Sironi 2019; Metzger et al. 2019) and the SMI in the context of relativistic shocks attracts more attention from astrophysics. In this seminar, by performing the world’s first 3DPIC simulation of relativistic shocks, he demonstrated that largeamplitude electromagnetic waves are indeed excited by the SMI even in 3D and that the wave amplitude is significantly amplified and comparable to that in pair plasmas due to a positive feedback process associated with ionelectron coupling. Based on the simulation results, he discussed the applicability of the SMI for FRBs. Reported by Shigehiro Nagataki

20220422
今週の論文Week 4, April 2022
Title: GRB Prompt Emission: Observed Correlations and Their Interpretations Author: Tyler Parsotan, Hirotaka Ito arXiv: http://arxiv.org/abs/2204.09729v1 Title: Fedder type criteria for quasi$F$splitting Author: Tatsuro Kawakami, Teppei Takamatsu, Shou Yoshikawa arXiv: http://arxiv.org/abs/2204.10076v1

20220420
今週の注目人物Selfintroduction: José Said GutiérrezOrtega
¡Hola! This is José (ホセ). I am a Mexican biologist in search of knowledge and interactions with scientists in all disciplines. I obtained my bachelor's degree in Mexico and completed my graduate studies in Japan: two countries where I grew up as a researcher, and where I also had great experiences working in science education. I joined iTHEMS as a SPDR in April 2022, and this transition represented an extraordinary chance for me to expand my research lines and interests. My scientific background is in evolutionary biology and ecology. Therefore, the main questions that motivate my studies are “how is the origin of the species?”, “why are species the way they are?”, “why do species change over time?”, “how do species interact with the environment and other species?”. To answer that kind of questions, I have gained abilities in phylogenetics, phylogeography, population genetics, plant systematics, botany, taxonomy, and population ecology. If these prior skills are useful for your research, or if you want to start something completely new, I am always available to work together with you. よろしくおねがいします！

20220418
お知らせ“科学”からの招待状『質量とは何か この宇宙に存在する物質の根本的性質とその起源を考える』放送大学（BS 231ch）にて4月24日（日）より放送！
「質量」という物理の基礎概念に焦点をあて、その理解の歴史的変遷について学ぶ4回シリーズが放送大学（BS 231ch）にて4月24日（日）より放送開始します。 初田 哲男（iTHEMS プログラムディレクター）、矢崎 紘一（iTHEMS 研究嘱託）、ゴードン・ベイム（iTHEMS 客員主管研究員）が「第4回これで物質の質量の起源はわかったか？」に出演します。放送は5月15日(日) 20:15～、6月26日(日) 8:15～（再）の予定です。 詳細は関連リンクをご覧ください。

20220418
今週の注目人物Selfintroduction: Yuto Moriwaki
Quantum field theory is a physical theory that describes a wide range of phenomena from the subatomic world to the cosmic scale, and can be regarded as a fruit of human wisdom. However, quantum field theory has not yet been mathematically formulated. This problem perhaps asks us, "How do we formulate space?" According to the philosophy of algebraic geometry, "space and algebra" are almost the same thing. Here, the algebra is a collection of functions (classical fields). So let us consider the algebra consisting of quantum fields. The "classical algebra" is associative, whereas the "quantum algebra" is nonassociative. What should be the corresponding space? I am currently studying this algebra of quantum fields in the case of twodimensional quantum field theory. In my previous research, I have worked mathematically on (1) a formulation of the algebra of twodimensional conformal field theory, (2) constructions of examples, and (3) a construction of nonperturbative deformations. More recently, I have returned to the question of "space" a bit, studying the axioms (consistency) of quantum field theory from a viewpoint of an operad structure of moduli spaces and higher categories. I was originally a pure mathematician studying representation theory. Crossing the field into physics has been fruitful for my life, although there is still a lot I don't understand. I am very happy to be here at iTHEMS and hope to have good interactions and coevolution with many researchers.

20220415
今週の注目人物Selfintroduction: Shou Yoshikawa
My name is Shou Yoshikawa. I joined RIKEN iTHEMS as an SPDR in April 2022. I am a mathematician studying algebraic geometry. I am interested in an analog of the existence of KählerEinstein metric to positive characteristic. Algebraic geometry in positive characteristic is a purely mathematical subject, however, the Einstein metric is deeply related to Physics. I hope that we find a new relation between mathematics and other sciences studying such analogies.

20220415
今週の注目人物Selfintroduction: Daiki Kumakura
My name is Daiki Kumakura. I joined iTHEMS as JRA (Junior Research Associate) in April 2022. My research fields are microbial evolutionary ecology and mathematical biology. Still undergraduate, I researched the metabolism of deep marine microbes with transcriptome analysis and comparative genome analysis. Because I am interested in the evolutionary process of microbes with the ecological interactions, I currently have researched the coevolution of microbes with theoretical analysis. Then, I do interdisciplinary research of fieldwork and theoretical simulation. The main field is a hot spring (Japanese is an onsen). I sample the sediments and water at each location and do bioinformatics. In the theoretical analysis, I construct mathematical modeling and simulation. I have the unique experience of discussing with theoretical researchers in various fields at iTHEMS. Through this interdisciplinary research and discussion, I hope to make my doctoral course meaningful.

20220415
今週の注目人物Selfintroduction: Taketo Sano
My name is Taketo Sano. I joined iTHEMS as a special postdoctoral researcher in April 2022 after I got the Ph.D. in mathematical sciences from the University of Tokyo. My research area is in lowdimensional topology and knot theory. I am interested in the intersection of (or interaction between) topology and combinatorics. Spaces are inherently infinite and beyond direct computations, while their algebraic images (under some nice mappings) are usually more tractable, and in some cases algorithmically computable. When one finds nice properties in the algebraic level, it is natural to expect that they are reflections of some hidden structures in the spacial level. My aim is to investigate the nature of the unseeable spaces through their algebraic images, by using theoretical tools (from algebraic topology, homotopy theory and category theory) together with computer powers.

20220414
今週の論文Week 3, April 2022
Title: The closest lineage of Archaeplastida is revealed by phylogenomics analyses that include Microheliella maris Author: Euki Yazaki, Akinori Yabuki, Ayaka Imaizumi, Keitaro Kume, Tetsuo Hashimoto, Yuji Inagaki Journal Reference: Open Biology 12: 210376 (2022) doi: https://doi.org/10.1098/rsob.210376 Title: Quantum Simulation for High Energy Physics Author: Christian W. Bauer. Zohreh Davoudi, A. Baha Balantekin, Tanmoy Bhattacharya, Marcela Carena, Wibe A. de Jong, Patrick Draper, Aida ElKhadra, Nate Gemelke, Masanori Hanada, Dmitri Kharzeev, Henry Lamm, YingYing Li, Junyu Liu, Mikhail Lukin, Yannick Meurice, Christopher Monroe, Benjamin Nachman, Guido Pagano, John Preskill, Enrico Rinaldi, Alessandro Roggero, David I. Santiago, Martin J. Savage, Irfan Siddiqi, George Siopsis, David Van Zanten, Nathan Wiebe, Yukari Yamauchi, Kübra YeterAydeniz, Silvia Zorzetti arXiv: http://arxiv.org/abs/2204.03381v1 Title: GoussarovPolyakViro Conjecture for degree three case Author: Noboru Ito, Yuka Kotorii, Masashi Takamura arXiv: http://arxiv.org/abs/1905.01418v3

20220414
セミナーレポートiTHEMS Biology Seminar by Dr. Hiroshi Yokota on April 14, 2022
In iTHEMS biology seminar on April 14th, I introductory talked about the coarsegrained molecular dynamics simulation by using Langevin equation which is the equation of motion including the interaction, the friction and the random force. First, I mentioned the chromosome formation dynamics as an example of the application range of the simulation. Next, I explained the Langevin equation and its intuitive picture. Then, I showed the discretized Langevin equation which keeps the stochastic properties of the random force term. Finally, I showed some examples of Langevin simulation. Many questions and discussions arose from the audience. Thank you very much!

20220411
ホットトピックiTHEMS Starter Meeting for FY2022 on April 8, 2022
The iTHEMS Starter Meeting for FY 2021 was held over Zoom as past two years’ meeting to kick off its activity for FY 2022. Over seventy iTHEMS members, frequent visitors and colleagues from other institute got together and introduced each other.

20220408
リサーチニュースRIKEN Research: Ringing black holes could put general relativity to the test
Typical overtone chords in the gravitational waves produced when black holes collide could be used to test general relativity, a mathematical analysis by a RIKEN physicist has shown [1]. When black holes merge, they generate gravitational waves, which ripple outward like sound waves from a ringing bell. In theory, these gravitational waves can be broken down into tones and overtones—like in music—based on their different frequencies and the rate at which they dampen and die out. But in practice, gravitationalwave detectors are not yet sensitive enough to definitively pick up the overtones. However, cosmologists are keen to measure the precise oscillation pattern because it can tell them more about a black hole’s properties. In particular, the mass of the black hole and the rate at which it is spinning can be calculated from the damping rate and frequency. “It’s like when you hear an instrument, you can understand if it is a guitar or a piano,” says Naritaka Oshita of the RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS). To read more, please visit the related link.

20220407
今週の注目人物Selfintroduction: Makiko Nio
She has been involved in precision calculations of Quantum Electrodynamic(QED), such as energy spectra of simple hydrogenlike atoms and the anomalous magnetic moments of the electron and the muon. The results of the calculations are used to determine the value of the finestructure constant that governs any electromagnetic phenomena. The QED results are also essential to test the Standard Model(SM) of elementary particles and to find something new beyond the SM by comparing theoretical predictions to measurements.

20220407
今週の論文Week 2, April 2022
Title: Ribbon YetterDrinfeld modules and tangle invariants Author: Kazuo Habiro, Yuka Kotorii arXiv: http://arxiv.org/abs/2204.02551v1 Title: Dominant Andreev Reflection through Nonlinear RadioFrequency Transport Author: Tingyu Zhang, Hiroyuki Tajima, Yuta Sekino, Shun Uchino, Haozhao Liang arXiv: http://arxiv.org/abs/2204.01356v2

20220406
リサーチニュースThe Horse: Breeding Mares Early in Life Might Lead to Early Fertility Decline
Jeffrey Fawcett (Senior Research Scientist, iTHEMS) and his research was featured in an article in The Horse. If you want to breed an older mare, you might consider how old she was when she was first bred. According to a new study in Japanese racehorses, broodmare fertility appears to decrease slowly over the years, on a downhill slope that follows her number of breeding years—and not just her age. “Our results suggest that the fertility of a mare is the highest at (her) first year breeding and gradually declines every year,” said Jeffrey Fawcett, PhD, a biologist and senior research scientist at RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS), in Saitama, Japan. To read more, please visit the related link.

20220406
今週の注目人物Selfintroduction: Tomoya Naito
My name is Tomoya Naito. I joined RIKEN iTHEMS as an SPDR in April 2022, while I have participated in many activities in iTHEMS including the iTHEMSphys study group and the iTHEMS mathphys working group so, probably, some of you have known me. My research topics are related to computational quantum manybody problems, especially density functional theory (DFT). In principle, one can obtain all the properties of quantum manybody problems by solving the manybody Schrödinger or Dirac equation; however, it is, in practice, difficult to solve it. DFT, developed by Hohenberg, Kohn, and Sham, is one of the efficient methods to solve such problems. DFT has been applied to the study of atomic nuclei, atoms, molecules, and solids for decades, while there are still many fundamental things to be solved or understood. My research topics are briefly divided into two parts: fundamental studies of the DFT and studies of quantum manybody problems (atomic nuclei, atoms, molecules, and solids) using DFT. Recently, I have started an astrophysical study using knowledge of nuclear physics and a study of the mathematical aspect of DFT in collaboration with iTHEMS (previous or current) members. I look forward to extending collaborations with iTHEMS colleagues!

20220406
リサーチニュースRIKEN Research: Thermal electrons play key role in determining emissions from gammarayburst afterglows
he presence of unusually energetic gamma rays seen in some afterglows from intense gammaray bursts (GRBs) could be explained by a new mathematical model developed by RIKEN researchers1. This finding could help to shed light on the origin of GRBs. A GRB is a spectacular eruption of energy produced by violent events such as the explosive death of a massive star, or the collision of two neutron stars. A GRB also shoots a jet of matter and energy into the material that surrounded the star, shocking particles such as protons and electrons and causing them to emit radiation. The emitted photons, ranging from radio waves to gamma rays, can be detected from Earth as a GRB afterglow. The vast majority of GRB afterglow observations can be explained by current theories, which should come as no surprise: they wouldn’t be the current theories if they didn’t match reality. But the afterglows of two recent GRBs produced gamma rays with unusually high energies that strain these theories. “The surprise with these two bursts was that we had never detected photons this energetic before,” says Donald Warren of the RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS). To read more, please visit the related link.

20220406
今週の注目人物Selfintroduction: Jizhou Li
My name is Jizhou (GJoe) Li. Born and raised in Beijing, got my PhD from the Washington State University, I’m now thrilled to join the RIKEN iTHEMS team as a postdoc researcher. A theoretical physicist by training, I have worked on nonlinear dynamical systems and quantum chaos during my PhD and postdoc years. After joining the RIKEN in April 2022, I will embark on a new journey in the field of computational virophysics to study the dissemination of viruses in various circumstances, as well as the interactions between the viruses and the hosts environments. Looking forward to expand my spectrum and learn from collaborators in different fields.

20220406
今週の注目人物Selfintroduction: Keiichi Morita
My name is Keiichi Morita, and I joined iTHEMS in April 2022 as a junior research associate / student trainee. I am now involved in a Ph.D. program at the SOKENDAI University. The main question of my research is how adaptive evolution can determine species coexistence and structures of ecological communities. I focus on rapid adaptation which can change the strength and directions of species interactions and finally affect population dynamics. I hope to understand how the evolution of an individual phenotype can affect species coexistence by formulating transient processes and finding conditions of coexistence from analysing and simulating my mathematical models. I consider analyzing experimental data and demonstrating my mathematical models. My final goal is to discover a general rule in ecology. I am looking forward to interacting with other members working with various interests in iTHEMS and finding a new direction of research out of it.

20220401
プレスリリース理化学研究所数理創造プログラム、東京大学教養学部と京都大学理学部 オンライン授業を用いた新しい大学間連携講義を開設
理化学研究所（理研）数理創造プログラムおよび東京大学教養学部、京都大学理学部は、2022年4月より大学間連携オンライン講義システムを新たに開設し、両学部生を対象として数理科学のさまざまな側面に関する授業を開始します。東京大学、京都大学の教員だけでなく、理研をはじめとする研究機関に所属する若手研究者が連続講義を行い、受講者はそれぞれの大学の科目として履修し、単位を取得できます。この新しい形態の講義により、受講者は学部の早い段階で現代社会の基盤となる数理科学の基礎と応用を最前線の研究者から学ぶことができます。同時に、大学の壁を越えた若手人材の育成が可能となります。授業の中で若手研究者と学生が活発な議論を行うことで、基礎科学研究の発展はもちろんのこと、将来の社会におけるイノベーションを生み出す人材育成にもつながると期待できます。 詳細は関連リンクをご覧ください。

20220401
セミナーレポートiTHEMS Biology Seminar by Dr. Euki Yazaki on March 17, 2022
At the March 17th seminar , I presented my research. It was mainly an analysis of the phylogenetic position of orphan organisms (organisms whose phylogenetic position is unknown) based on largescale sequence data, and in addition, I showed that huge lineages (Archaeplastida), including plants, are monophyletic. Although monophyly of Archaeplastida has been debated for many years, this study clarified that they are monophyletic and why they were not monophyletic in previous research. The seminar was very active, with many questions about the methods of phylogenetic analysis and biological questions.

20220401
今週の注目人物Selfintroduction: Yan Lyu
I am a Ph. D candidate in Peking University, China, and I joined iTHEMS on April 1st 2022 as a student trainee. I am interested in understanding the interactions between hadrons from the fundamental theory, i.e., quantum chromodynamics (QCD). It is in some sense similar with determining the Coulomb interaction between two objects by calculating a simple integral using a pen and a piece of paper, like highschool students usually do in their physical class. However, as far as QCD is concerned, such an integral is too complicated to be done by using a pen and a piece of paper, thus I employ the socalled lattice QCD method to calculate such an integral by supercomputers. Once the interactions are determined from QCD, one can use them to various systems from nuclei to neutron star. I am very happy to join iTHEMS, and I look forward to interacting with people from various fields.

20220401
今週の注目人物Selfintroduction: Kotaro Murakami
My name is Kotaro Murakami and have joined iTHEMS since April 2022 as a student trainee. My research is to solve the mystery of hadrons from the firstprinciple calculation of quantum chromodynamics (QCD). QCD is a theory describing the dynamics of quarks and gluons, and hadrons are composed of these particles. There are several hadrons we do not know how are created from quarks and gluons, which are called exotic hadrons. My ultimate goal is to identify all of the hadrons including exotic hadrons from QCD. I am working on the lattice QCD studies of baryon resonances from mesonbaryon scatterings. I hope to have fruitful discussions in iTHEMS with not only people in particle physics or hadron physics but people in other fields.

20220401
今週の注目人物Selfintroduction: Xun Liu
My name is Xun Liu, and I joined iTHEMS in April 2022 as a student trainee. I am now involved in a PhD program at the University of Tokyo. My current research project and interest mainly lies in the field of twodimensional conformal field theory, string theory, and string field theory. I am also interested in the relationship of these fields with formal mathematical topics, including group and representation theory, and analytical geometry. I am looking forward to interacting with mathematicians to form a more mathematical welldeveloped language in describing CFT and string theory.

20220331
受賞情報Dr. Miyazaki receives FY2021 RIKEN Excellent Achievement Award
Hiroyasu Miyazaki (Visiting Scientist, iTHEMS) received "FY2021 RIKEN Excellent Achievement Award (RIKEN BAIHO Award)" on March 23, 2022 for his achievement on "Development of generalized theory of motives". Congratulations !

20220331
今週の論文Week 5, March 2022
Title: Diffeomorphisms of 4manifolds with boundary and exotic embeddings Author: Nobuo Iida, Hokuto Konno, Anubhav Mukherjee, Masaki Taniguchi arXiv: http://arxiv.org/abs/2203.14878v1 Title: Femtoscopic study on $DD^*$ and $D\bar{D}^*$ interactions for $T_{cc}$ and $X(3872)$ Author: Yuki Kamiya, Tetsuo Hyodo, Akira Ohnishi arXiv: http://arxiv.org/abs/2203.13814v1

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プレスリリース制御シミュレーション実験 －気象制御に向けた新理論－
理化学研究所（理研）計算科学研究センターデータ同化研究チームの三好建正チームリーダー（開拓研究本部三好予測科学研究室主任研究員、数理創造プログラム副プログラムディレクター）、キウェン・ソン大学院生リサーチ・アソシエイトの研究チームは、気象制御に向けた制御シミュレーション実験の新理論を考案しました。 本研究成果は、激甚化しつつある台風や豪雨を制御し、極端風水害の脅威を軽減するための理論研究の発展に貢献すると期待できます。 続きは、関連リンクをご覧ください。

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ホットトピックiTHEMS NOW & NEXT FY2021 was held on March 25, 2022
The annual inhouse gathering entitled iTHEMS NOW and NEXT FY2021 was held on March 25th online. The gathering is an occasion that we discuss the current status and future perspectives on our research and organization. The event started with five keynote talks given by Takeru Yokota, Yalong Cao, Ryosuke Iritani, Ryo Namba, Keita Mikami. After a short break a session on the proper practices in conducting scientific researches followed during lunch time. In the session, the participants discussed their research practices in small groups and later shared their discussions with all. In the afternoon, each working group and study group made their progress reports. Program Director Hatsuda’s remarks concluded the gathering.

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セミナーレポートQuantum Matter Seminar by Dr. Tiantian Zhang on March 24, 2022
The Quantum Matter Study Group invited Dr. Tiantian Zhang from Tokyo Institute of Technology to talk about the local and global topology for Tgprotected Z_{2} Dirac points. In the beginning, by introducing the topological phase in the gapped and gapless systems, she discussed the conventional and Z_{2} Dirac points. Surprisingly, she established gaugeinvariant charge formula and bulksurface correspondence for Z_{2} Dirac points, which can give a full understanding about the topology of Tgprotected Z_{2} Dirac points. Then, she proposed the first Z_{2} Dirac material candidate Li2B4O7 for further exploration. Reported by Congcong Le

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イベントスケジュールEvents for the 5th week of March 2022
Wednesday, March 30, 13:30– 15:00 NEW WG Seminar Thursday, March 31, 10:00 11:00 iTHEMS Biology Seminar

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セミナーレポートHow is mathematics utilized in society?  Exploring the Essence of Mathematical Research Special Lecture by Shigefumi Mori and Takashi Sakajo on March 12, 2022
On March 12, a zoom discussion by two mathematicians, Takashi Sakajyo (Kyoto U./iTHEMS) and Shigefumi Mori (KUIAS/iTHEMS), was held as an iTHEMS x academist special event "How is mathematics utilized in society?" More than 380 people from academia, schools, and companies have joined online. After the introductory talks on the usefulness of mathematics in modern times by Sakajyo san, and on the beauty and joy of mathematics by Mori san, they had interesting discussions on three topics, the relation between mathematics and society, mathematics education, and how do mathematicians face mathematical problems? Reported by Tetsuo Hatsuda

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今週の論文Week 4, March 2022
Title: Quantum and classical annealing in a continuous space with multiple local minima Author: Yang Wei Koh, Hidetoshi Nishimori arXiv: http://arxiv.org/abs/2203.11417v1 Title: Dehn twists and the Nielsen realization problem for spin 4manifolds Author: Hokuto Konno arXiv: http://arxiv.org/abs/2203.11631v1 Title: Neutron star mass formula with nuclear saturation parameters Author: Hajime Sotani, Hajime Togashi Journal Reference: Phys. Rev. D 105(6), 063010 (3/2022) arXiv: http://arxiv.org/abs/2203.09004v1

20220322
ホットトピックFarewell message from Dr. Akinori Tanaka
Our colleague Akinori Tanaka moves on to a new carrier at RIKEN AIP as of April 1st. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Akinori Tanaka: First of all, I would like to thank my colleagues, assistants, and all the people for sharing time in iTHEMS. I really enjoyed discussing and chatting, even though I spent a lot of time online. In fact, this is the 2nd time for me to leave here. When I started my research as a member of iTHES, not iTHEMS at that time, I was working on theoretical physics. But, in addition to my own research, I also enjoyed chatting with my colleagues and getting new concepts: machine learning and related topics, and it opened up my next career. As a result, I returned to iTHEMS as a machine learning researcher, as you know. It was very surprising for me that all the activities were really sophisticated compared to the ones in iTHES, and I was happy to participate in the activities in information theory study group, SSP workshop, and chatting after the coffee meeting. Now I leave this message as if this was farewell, but it's not. I will move to RIKEN AIP from this April as a senior research scientist, but hold a post in iTHEMS also. I would like to deepen my thoughts on machine learning from mathematical, biological, and physical perspectives, so I'm happy if all of you discuss/chat with me as I have so far, even after April.

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ホットトピックFarewell message from Dr. Kanato Goto
Our colleague Kanato Goto moves on to a new carrier at Kyoto University as of April 1st. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Kanato Goto: I am leaving iTHEMS to move to Yukawa Institute for Theoretical Physics at Kyoto University. I have been very happy to have had the opportunity to work with you all for the past three years. The experience of discussing with scientists from various fields at iTHEMS is invaluable for my research carrier. The first year I joined iTHEMS, I stayed in the U.S. Regrettably, the Corona disaster struck during my stay, and I was deprived of the opportunity to interact with you all in person, even after returning to Japan. I hope to visit iTHEMS in the near future and discuss you again. I cannot thank the assistants enough for their great help. Thanks to them, I could devote myself to my research without any inconvenience. Thank you very much, all the iTHEMS members! See you again soon!

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ホットトピックFarewell message from Dr. Naomi Tsuji
Our colleague Naomi Tsuji moves on to a new carrier at Kanagawa University as of April 1st. We all will miss her and wish her the best of luck in her latest endeavor. Here is a message from Naomi Tsuji: Since I joined iTHEMS in April 2020, my research life at iTHEMS completely overlapped with the pandemic. At first, I found it difficult to get to know each other and communicate with the other iTHEMS members through online meeting systems, but gradually it became possible and comfortable to me. I have been working on mainly data analysis of Xray or gammaray observations from astrophysical objects at iTHEMS, a group of theorists. I was glad that some members showed their interest in my study, and it was so exciting and stimulating to discuss about it. I wish I could have more discussion with many of the iTHEMS members in person and hope those days will come in the near future. Until then, let us stay healthy and have good science!

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ホットトピックFarewell message from Dr. Yukimi Goto
Our colleague Yukimi Goto moves on to a new carrier at Kyushu University as of April 1st. We all will miss her and wish her the best of luck in her latest endeavor. Here is a message from Yukimi Goto: It may not be obvious to those in other fields, but iTHEMS is a unique place for Japanese mathematicians. Japanese mathematicians do not have many opportunities to talk with researchers in fields other than their own. I am an applied mathematician, but I did not have a chance to talk casually with physicists at university. After coming to iTHEMS and talking with physicists and biologists, I found that they are very interested in and expect a lot from mathematics. When I talked about my research, they always tried to understand it and asked me what kind of problems we could solve in mathematics. I enjoyed discussing with them, and it motivated me to do research. Although it was only two years and I met most of them online, I am grateful that I had such a wonderful time with them.

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ホットトピックFarewell message from Dr. Takashi Okada
Our colleague Takashi Okada moves on to a new carrier at Kyoto University as of April 1st. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Takashi Okada: I joined iTHEMS in 2018. My main workplace was in Hallatschek group, UC Berkeley. I researched on biophysics & evolutionary dynamics and learned a lot of things there. I also enjoyed working with iTHEMS members on interdisciplinary projects. I believe that some projects were made possible only by collaboration with wonderful iTHEMS members. I really appreciate iTHEMS' support during my longterm stay in Berkeley. Thanks to iTHEMS support, I could focus on work without any problems during this pandemic. From this spring, I am moving to Mochizuki Lab (Kyoto Univ) as a ProgramSpecific Associate Professor. The scientific atmosphere of ITHEMS is so great, and I hope that I can continue to collaborate with great members in iTHEMS. Let's keep in touch!

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セミナーレポートiTHEMS Math Seminar by Dr. Lin Li on March 18, 2022
In March 18, there was a seminar by Dr. Lin Li. He explained his theoretical research on the control of hurricane. The main difficulty is that the order of the energy of the so large that it is 10^{6} times larger than the energy we could use. To overcome this difficulty, he explained some ideas and his simulation on how his ideas will work. Reported by Keita Mikami
202件のニュース / 2022年