ニュース
187件のニュース / 2020年
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2020-10-01
今週の注目人物
Self-introduction: Ken Furukawa
I am Ken Furukawa. My research area is the mathematical theory of partial differential equations related to the fluid dynamics and diffusion phenomena. More specifically, we studied mathematically rigorous justification of the derivation of the primitive equations by the Navier-Stokes equations. The primitive equations have nice properties on well-posedness and have a strong connection with the Navier-Stokes equations. We obtained some results on the well-posedness of the Navier-Stokes equations in this research. Recently, I have been interested in the mathematical aspect of data assimilation. Data assimilation is very useful to obtain a plausible forecast and is also closely related to our lives. However, mathematically rigorous studies of data assimilation from the mathematical theory of PDE are under development. I will study data assimilation from the view PDE point of view.
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2020-09-30
ホットトピック
Farewell message from Dr. Genki Ouchi
Hello. I am Genki Ouchi, a special postdoctoral researcher in iTHEMS. I am leaving iTHEMS and moving to graduate school of mathematics, Nagoya university as an assistant professor. I joined iTHEMS on April 2018. Since then, it has been two and a half years. I learned a lot of things from iTHEMS. Before I came to iTHEMS, I was just an “algebraic geometer”. I studied only algebraic geometry and related topics. After joining iTHEMS, I got opportunities to learn other topics in mathematical science. Especially, I study network science with mathematicians, physicists and network scientists now. With an experience at iTHEMS, I become a “mathematician”. I wish that interdisciplinary activities in iTHEMS bear fruit over the long run. I would like to thank all iTHEMS members for your kind support and help. I am looking forward to seeing you again.
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2020-09-30
ホットトピック
Farewell message from Dr. Kenta Sato
Hello. I am Kenta Sato, a Special Postdoctral Resercher at iTHEMS. I am moving to Kyusyu University as an assistant professor. It is a great pleasure for me to spend one and a half years at iTHEMS because I have been stimulated by the open atmosphere of iTHEMS and by the energetic activities of each member. It helps me to broaden my perspective. I would like to say thanks to everyone in iTHEMS. I am looking forward to seeing the successful development of iTHEMS in the future.
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2020-09-29
受賞情報
Dr. Ryosuke Iritani and Dr. Takashi Okada received 15th Young Scientist Award of JSMB
It is our great pleasure to inform you that 15th Young Scientist Award (Japanese Society for Mathematical Biology) was awarded to our iTHEMS colleagues, Ryosuke Iritani for his contribution to the theory of evolutionary ecology and Takashi for his contribution to the theory of chemical reaction networks. Many congratulations to Ryosuke and Takashi !!
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2020-09-25
今週の注目人物
Self-introduction: Catherine Beauchemin
Bonjour! I was already a member of iTHEMS as a Senior Visiting Scientist so probably you already know me. But since September 2020, I became a Deputy Program Director of iTHEMS. I was looking forward to spending more time at RIKEN, working more closely with everyone, but unfortunately, with COVID-19, for now I have to stay in Toronto. As you maybe know, I am a professor of physics, but my research is in the field of virophysics (ヴイルス物理学). I apply the techniques of physics to virology. More generally, I like applying the methods of physics and computational methods to fields where theoretical/quantitative analysis is less common, like biology and health research, or even ergonomics! I think the methodologies developed in physics can translate to many other fields and provide new insights. Most of my work involves/requires direct collaborations with experimental virologists. I also really enjoy convincing other physicists and mathematicians to join in solving these types of problems across disciplines. For me, iTHEMS is an ideal environment to develop such collaborative projects. In my new role as Deputy Program Director, I want to do my best to help support the young researchers in iTHEMS, and make sure they have everything they need to succeed at their goals. I want to help foster new collaborations, through which everyone can learn new skills, or get help to bring their research to the next level. I have a few ideas that I want to share with all of you over time. If you have some thoughts or concerns, or if you want to discuss something with me, please send me an email anytime. I am happy to get to know you better.
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2020-09-25
セミナーレポート
Biology Seminar by Dr. Kyosuke Adachi on September 23, 2020
On September 23rd, Kyosuke Adachi gave a talk at the iTHEMS Biology Seminar on phase transitions in Biology. He first introduced the concept of phase transition and its possible application to understanding a number of biological phenomena. Then, he talked about his research on modelling the structural transition of chromatin states, and also about equilibrium and non-equilibrium dynamics. His research is really nice in how it engages both biologists and physicists, and many people seemed to enjoy his talk. In particular, the topic of chromatin dynamics is an area many molecular biologists are interested in at the moment, and we will be looking forward to hearing about his progress in the future.
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2020-09-24
今週の論文Week 4 of September
Title: Polynomial growth of out-of-time-order correlator in arbitrary realistic long-range interacting systems Author: Tomotaka Kuwahara, Keiji Saito arXiv: http://arxiv.org/abs/2009.10124v1 Title: Rainbow Nambu-Goldstone modes under a nonequilibrium steady flow Author: Yuki Minami, Hiroyoshi Nakano, Yoshimasa Hidaka arXiv: http://arxiv.org/abs/2009.10357v1 Title: Path integral of neutrino oscillations Author: Kazuo Fujikawa arXiv: http://arxiv.org/abs/2009.08082v1
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2020-09-18
セミナーレポート
Biology Seminar by Dr. Hye Jin Park on September 16, 2020
On 16th September, Hye Jin Park (Asia Pacific Center for Theoretical Physics; APCTP) gave us a talk about her work on eco-evolutionary dynamics. She specifically looked at what if there are novel mutations that generate a nonexistent phenotype (temporal emergence of different phenotypes) and how it affects the evolution of cyclic dominance. She took advantage of introducing novel phenotypes to construct phylogenetic-alike trees, which contain some information for which types are similar or dissimilar. She found that similar types are unlikely to exhibit cyclic dominance. We discussed how we can apply the theory to real systems and what factors are important. Thank you so much, Hye Jin for the fantastic talk! -Ryosuke Iritani
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2020-09-17
今週の論文Week 3 of September
Title: Effective field theory of magnon: Dynamics in chiral magnets and Schwinger mechanism Author: Masaru Hongo, Toshiaki Fujimori, Tatsuhiro Misumi, Muneto Nitta, Norisuke Sakai arXiv: http://arxiv.org/abs/2009.06694v1 Title: Are atoms spherical? Author: Tomoya Naito, Shimpei Endo, Kouichi Hagino, Yusuke Tanimura arXiv: http://arxiv.org/abs/2009.05955v1 Title: Accuracy of relativistic Cowling approximation in protoneutron star asteroseismology Author: Hajime Sotani, Tomoya Takiwaki arXiv: http://arxiv.org/abs/2009.05206v1 Title: Effective models of a semi-quark gluon plasma Author: Yoshimasa Hidaka, Robert D. Pisarski arXiv: http://arxiv.org/abs/2009.03903v1
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2020-09-14
受賞情報
三好建正チームリーダーが「令和2年度防災功労者内閣総理大臣表彰」を受賞
It is our great pleasure to inform you that our colleague, Takemasa Miyoshi, received "Commendation by the Prime Minister for Disaster Prevention (2020)”. The awards ceremony was held on Sep.4, 2020 at the Prime Minister's Office in Tokyo.
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2020-09-11
セミナーレポート
Math Seminar by Dr. Ken Furukawa on September 8, 2020
On September 8, there was a math seminar by Dr. Ken Furukawa. He gave a talk entitled Maximal Regularity and Partial Differential Equations. In the first part of his talk, the speaker explained the maximal regularity of parabolic partial differential equations and various sufficient conditions for the maximal regularity. Especially he introduced some functional calculus to obtain the analytic semigroup. In the second part, the speaker explained his recent collaboration work on the primitive equation and its relationship to the Navier-Stokes equation. He first shows that we can formally obtain primitive equations from the Navier-Stokes equation on the thin domain. He then explained his recent collaboration work which justifies this formal derivation of the primitive equation and how the sufficient conditions in the first talk work.
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2020-09-10
今週の論文Week 2 of September
Title: 3D modeling from the onset of the SN to the full-fledged SNR: Role of an initial ejecta anisotropy on matter mixing Author: Antonio Tutone, Salvatore Orlando, Marco Miceli, Sabina Ustamujic, Masaomi Ono, Shigehiro Nagataki, Gilles Ferrand, Emanuele Greco, Giovanni Peres, Donald C. Warren arXiv: http://arxiv.org/abs/2009.01157v1 Title: Snowmass 2021 Letter of Interest: The GRAMS Project: MeV Gamma-Ray Observations and Antimatter-Based Dark Matter Searches Author: Tsuguo Aramaki, Jonathan Asaadi, Yuto Ichinohe, Yoshiyuki Inoue, Georgia Karagiorgi, Jon Leyva, Reshmi Mukherjee, Hirokazu Odaka, Kerstin Perez, William Seligman, Satoshi Takashima, Naomi Tsuji, Hiroki Yoneda arXiv: https://arxiv.org/abs/2009.03754 Title: The index theorem of lattice Wilson--Dirac operators via higher index theory Author: Yosuke Kubota arXiv: http://arxiv.org/abs/2009.03570v1 Title: Area law of non-critical ground states in 1D long-range interacting systems Author: Tomotaka Kuwahara, Keiji Saito arXiv: http://arxiv.org/abs/1908.11547v2
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2020-09-10
ホットトピック
Farewell message from Dr. Yoshiyuki Inoue
Hello colleagues. I am Yoshiyuki Inoue, a senior research scientist here at iTHEMS. I am leaving iTHEMS and joining Osaka University as an associate professor. It has been almost three years since I came here. I would like to thank all the iTHEMS friends for your kind support and help, especially Hatsuda-san, Tada-san, and assistants. The open research atmosphere allowed me to expand my research area a lot, e.g., collaboration with other RIKEN researchers. I believe the interdisciplinary and academic freedom mind in iTHEMS is essential for future research. I will bring and spread this iTHEMS spirit in Osaka. Even after moving to Osaka, I will keep visiting our precious research place, iTHEMS (the coffee room, maybe?). I wish future success of iTHEMS research activity.
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2020-09-09
セミナーレポート
Biology Seminar by Dr. Masashi Tachikawa on September 9, 2020
On 9th September, Masashi Tachikawa (Kyoto University) gave us a talk on adaptive dynamics as a framework for evolutionary dynamics. He first gave us a quick overview for modeling evolution, and then introduced adaptive dynamics toolbox and pairwise invasibility plots to visualize trait-substitution processes towards evolutionarily singular points. He finally talked about how to capture evolutionary branching (two morphs emerging) using envelope with a trait value being tuned as-if a parameter. We all excitedly learned a lot from this talk. Thank you, Masashi! -Ryosuke Iritani
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2020-09-07
リサーチニュース
RIKEN NEWS: 優駿の生産を夢見て
The article written by Dr. Jeffrey Fawcett, Senior Research Scientist, was published in this month's RIKEN News. He wrote about the genetics of Thoroughbred horses and his research using genomic data of Japanese Thoroughbreds.
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2020-09-07
受賞情報
Dr. Yosuke Kubota received 2020 Takebe Katahiro Prize for Encouragement of Young Researchers
It is our greatest pleasure to inform you that our iTHEMS colleague, Yosuke Kubota received 2020 Takebe Katahiro Prize for Encouragement of Young Researchers from The Mathematical Society of Japan (MSJ) for his contribution to the "Applications of operator K theory in geometry”. This prize was established by MSJ in honor of the renowned Japanese Mathematician in Edo period, Katahiro Takeba (1664 –1739).
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2020-09-04
セミナーレポート
Biology Seminar by Dr. Miki Ebisuya on July 17, 2020
In 1638, Galileo Galilei proposed “the square-cube law”: the ratio of two volumes is greater than the ratio of their surfaces. This law enables us to understand why large animals like elephants need longer time to cool their body temperature than small ones like human. On July 17th, Miki Ebisuya at European Molecular Biology Laboratory (EMBL) explained why human needs longer time to develop her/his body than mouse, at the iTHEMS seminar. In fact, the speed of the segment formation ("taisetsu" in Japanese) of human is twice or three times as slow as that of mouse. By combining state-of-the-art experiments and a model with two variables, her group discovered that the difference of tempos is due to the difference of biochemical parameters. The talk was clear and enjoyable. And it was accessible to the diverse audience. As a mathematician asked during the talk, their discovery raises a new fundamental question about why reactions in human are slower than those in mouse. The question might be also answered by the collaboration between biology and mathematics in a future.
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2020-09-03
今週の論文Week 1 of September
Title: Untangling the complexity of market competition in consumer goods -A complex Hilbert PCA analysis Author: Makoto Mizuno, Hideaki Aoyama, Yoshi Fujiwara arXiv: http://arxiv.org/abs/2008.11327v1 Title: Parity operation for Majorana neutrinos Author: Kazuo Fujikawa arXiv: http://arxiv.org/abs/2008.11390v1 Title: Barthelonids represent a deep-branching metamonad clade with mitochondrion-related organelles predicted to generate no ATP Author: Euki Yazaki, Keitaro Kume, Takashi Shiratori, Yana Eglit, Goro Tanifuji, Ryo Harada, Alastair G. B. Simpson, Ken-ichiro Ishida, Tetsuo Hashimoto, Yuji Inagaki URL: https://royalsocietypublishing.org/doi/10.1098/rspb.2020.1538
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2020-09-03
セミナーレポート
iTHEMS Math-Phys joint seminar was held on August 31 and September 1, 2020
The iTHEMS Math-Phys joint seminar was held on August 31st and September 1st, inviting Makiko Sasada from University of Tokyo and Kenichi Bannai from Keio university / RIKEN AIP. This was a series of lectures entitled “Geometric Perspective for the Theory of Hydrodynamic Limits”. They explained to us their recent joint work with Yukio Kametani on hydrodynamic limits from algebraic/geometric view point. On Day 1, Sasada-san gave an introduction to hydrodynamic limits, and explained the motivation of the joint work and the key ideas. One of the goals of the theory of hydrodynamic limits is to derive macroscopic dynamics from microscopic evolution equations rigorously. There have been many results to this problem, but all of them depend on specific microscopic models. The long term goal of this joint work is to construct an abstract and universal theory of hydrodynamic limits. One of the most important ingredients of the theory of hydrodynamic limits is the “decomposition of closed forms”, which have been obtained by Varadhan and other people using very technical argument depending on models. One of the aims of this work is to give a more general and clear understanding of this type of decompositions. Their strategy is as follows: the microscopic data can be divided into topological (geometric) part and stochastic (analytic) part. For discrete models, the former one is modeled by a directed graph, the set of states at each vertex, and the interaction through edges. A typical analytic datum is the jump rate, i.e., the frequency of interaction. They observed that some important feature of hydrodynamic limits depends only on the geometric data, and as a consequence, they could avoid ad-hoc analytic estimations. Moreover, they obtain a version of Varadhan’s decomposition in a very general setting. On Day 2, Bannai-san gave a precise mathematical formulation of their main results and proofs. As explained above, the geometric part of microscopic model is given by a directed graph, a pointed set of states, and a function which represents the interaction through edges. From this set of data, we can form a configuration space, each point of which corresponds to a possible state on the graph (The interaction data induce the transition structure on the configuration space). On the configuration space, they consider a special type of functions / forms called “uniformly local functions / forms”, and construct a cohomology theory (uniformly local cohomology) associated to them. Surprisingly, the uniformly local cohomology captures all conserved quantities (macroscopic observables). Moreover, from this fact, they can derive a local form version of Varadhan’s decomposition. An important ingredient of the proof is the group cohomology, which is often used in the field of number theory. They assume the existence of a free group action on the graph (which is valid in many important examples), and apply a general theory of group cohomology. It is very surprising that a fundamental result in hydrodynamic limits is derived from an abstract algebraic theory, and it will provide us a new and clear understanding of this field.
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2020-09-03
セミナーレポート
Biology Short Talk by Dr. Ryosuke Iritani on September 2, 2020
On September 2, Ryosuke Iritani gave a lecture at iTHMES Biology Seminar. In this seminar, Ryo explained the principles of evolution in an easy-to-understand way, using examples such as the diversification of pet dogs and cruciferous plants, and changes in the structure of the gecko's hands. Especially, the formulation of adaptive evolution using Fokker planck equarion was introduced. His seminar will be very useful as a basic knowledge of evolutionary biology and mathematical biology that will be covered in future seminars.
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2020-09-02
リサーチニュース
Dr. Nagisa Hiroshima and Dr. Yoshiyuki Inoue were highlighted in an article of RIKEN 2020 about Dark Matter Search
It is our great pleasure to inform you that our iTHEMS colleagues, Nagisa Hiroshima and Yoshiyuki Inoue, are highlighted in RIKEN Annual Report 2020 for their leading role in organizing the iTHEMS "Dark Matter Working Group". This working group aims at creating a new domestic and international network of theoretical and experimental physicists who are interested in dark matter search.
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2020-09-02
ホットトピック
Dr. Jason Chang was ranked in the list of the most downloaded physics papers published in Scientific Reports in 2019
It is our great pleasure to inform you that the paper on quantum annealing by our iTHEMS colleague, Jason Chang, was ranked No.14 of the most downloaded physics papers published in Scientific Reports in 2019.
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2020-08-31
受賞情報
Dr. Martin Skrodzki received the best slammer award at GAIN20 Science Slam on Aug. 28, 2020.
The GAIN Science Slam is all about science communication. The objective is to impart current research results to a diverse audience in an understandable and entertaining way. Science Slams started in German university towns in the mid-2000s: Darmstadt, Braunschweig, Hamburg. Today, Science Slams are held all over Germany on a weekly basis. The virtual GAIN20 Science Slam took place in the Auditorium of the virtual GAIN20 conference on August 28, 2020. The annual GAIN conference is the largest German science and research career fair in the US. Early career researchers and representatives from all areas of the German research landscape come together for two days of exchange, learning and networking in a virtual space. Seven international researchers from various fields presented their findings in a five-minute pitch in front of the virtual audience. This virtual GAIN audience was the Science Slam Jury. The best slammer received a cash prize of $3,000, proudly presented by the German Center for Research and Innovation (DWIH). This year's winner is Dr. Martin Skrodzki from RIKEN iTHEMS. He gave a talk on seeing, recognizing, and self-driving cars. The talk is available on YouTube.
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2020-08-28
ホットトピック
Anew Calculation of Penguin Pooing Pressure by Hiroyuki Tajima
As posted in the Ig Nobel Prize web page, our iTHEMS friend Hiroyuki Tajima (Kochi Univ., former member of RIKEN Nishina Center) has published an interesting work "Projectile Trajectory of Penguin’s Faeces and Rectal Pressure Revisited" with Fumiya Fujisawa (Katsurahama Aquarium). Find how the gauge/gravity duality in particle physics is useful to find out the incredible power of penguin’s rectum!
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2020-08-27
今週の論文Week 4 of August
Title: Two relativistic Kondo effects from two HQETs Author: Yasufumi Araki, Daiki Suenaga, Kei Suzuki, Shigehiro Yasui arXiv: http://arxiv.org/abs/2008.08434v1 Title: Gravitational wave asteroseismology for low-mass neutron stars Author: Hajime Sotani arXiv: http://arxiv.org/abs/2008.09839v1 Title: Chirality-driven edge flow and non-Hermitian topology in active nematic cells Author: Lisa Yamauchi, Tomoya Hayata, Masahito Uwamichi, Tomoki Ozawa, Kyogo Kawaguchi arXiv: http://arxiv.org/abs/2008.10852v1
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2020-08-27
セミナーレポート
Biology Seminar by Dr. Gen Kurosawa on August 26, 2020
On August 26th, Gen Kurosawa gave a talk at the iTHEMS Biology seminar. The main topic of the talk was biological timing, and he introduced his work on mathematical modelling of circadian rhythm and hibernation. In addition, he also talked about his current effort in trying to apply theories developed in biology to understand the transaction network between companies. He clearly made a lot of effort to make the seminar accessible and enjoyable to people without background knowledge, and I'm sure many people appreciated that.
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2020-08-22
セミナーレポート
iTHEMS Theoretical Physics Seminar by Dr. Takuya Shimazaki on August 21, 2020
On August 21st (Fri.), Takuya Shimazaki (The University of Tokyo) gave an iTHEMS-phys seminar on an application of the Lefschetz thimble method to the Schwinger mechanism, or a particle production problem caused by strong electric fields. In the seminar, he has demonstrated a new formulation to estimate the particle production rate. The new formulation gives a good result even in some regimes where one cannot use the Dykhne–Davis–Pechukas (DDP) formula (a commonly used approximation in a two-level quantum system equivalent to the Schwinger mechanism). There were a lot of lively discussions, and the audience looked enjoying the seminar.
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2020-08-20
今週の論文Week 3 of August
Title: Gaussian concentration bound and Ensemble equivalence in generic quantum many-body systems including long-range interaction Author: Tomotaka Kuwahara, Keiji Saito arXiv: http://arxiv.org/abs/1906.10872v2
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2020-08-20
受賞情報
Prof. Gordon Baym received 2021 APS Medal for Exceptional Achievement in Research
Prof. Gordon Baym (iTHEMS Senior Visiting Scientist / UIUC) has received 2021 APS Medal for Exceptional Achievement in Research. This is the largest Society prize to recognize the achievement of researchers from across all fields of physics. This prize was established to recognize contributions of the highest level that advance our knowledge and understanding of the physical universe in all its facets. It is intended to celebrate scientific inquiry and the pursuit of knowledge. The citation says "For major discoveries in theoretical condensed matter and many-body physics, neutron star structure and composition, quark matter and quark-gluon plasma physics, and in atomic physics and ultracold quantum gases." Many congratulations, Gordon san!!
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2020-08-17
受賞情報
Dr. Chris Bourne received Best Paper Prize 2020, Journal of Physics A: Mathematical and Theoretical
It is our great pleasure to inform you that our iTHEMS colleague, Chris Bourne (Tohoku AIMR/ RIKEN iTHEMS), received Best Paper Prize 2020: Journal of Physics A (Mathematical and Theoretical). The Journal of Physics A Best Paper Prize has been awarded annually since 2009. All original research articles from 2018 and 2019 were eligible for consideration this year 2020. The publisher says "Nominations were assessed by the Section Editors and Editor-in Chief using the criteria of novelty, achievement, potential impact and presentation. your article was highly recommended and was considered to have excelled in all of these categories." Many congratulations, Chris!
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2020-08-13
今週の論文Week 2 of August
Title: Artificial magnetic field for synthetic quantum matter without breaking time reversal symmetry Author: Tomoki Ozawa arXiv: https://arxiv.org/abs/2008.02412
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2020-08-06
今週の論文Week 1 of August
Title: The error term in the Cesàro mean of the prime pair singular series Author: D. A. Goldston, Ade Irma Suriajaya arXiv: http://arxiv.org/abs/2007.14616v1 Title: Note on the number of zeros of ζ(k)(s) Author: Fan Ge, Ade Irma Suriajaya arXiv: http://arxiv.org/abs/2007.14617v1 Title: Money flow network among firms' accounts in a regional bank of Japan Author: Yoshi Fujiwara, Hiroyasu Inoue, Takayuki Yamaguchi, Hideaki Aoyama, Takuma Tanaka arXiv: http://arxiv.org/abs/2007.14630v1 Title: Value-Distribution of the Riemann Zeta-Function along its Julia Lines Author: Jörn Steuding, Ade Irma Suriajaya arXiv: http://arxiv.org/abs/2007.14661v1 Title: A singular series average and the zeros of the Riemann zeta-function Author: D. A. Goldston, Ade Irma Suriajaya arXiv: http://arxiv.org/abs/2007.16099v1 Title: Blazar Radio and Optical Survey (BROS): A catalog of blazar candidates showing flat radio spectrum and their optical identification in Pan-STARRS1 Surveys Author: Ryosuke Itoh, Yousuke Utsumi, Yoshiyuki Inoue, Kouji Ohta, Akihiro Doi, Tomoki Morokuma, Koji S. Kawabata, Yasuyuki T. Tanaka arXiv: http://arxiv.org/abs/2008.00038v1 Title: Avoided crossing in gravitational wave spectra from protoneutron star Author: Hajime Sotani, Tomoya Takiwaki arXiv: http://arxiv.org/abs/2008.00419v1 Title: Activity-induced phase transition in a quantum many-body system Author: Kyosuke Adachi, Kazuaki Takasan, Kyogo Kawaguchi arXiv: http://arxiv.org/abs/2008.00996v1 Title: Counting Nambu-Goldstone modes of higher-form global symmetries Author: Yoshimasa Hidaka, Yuji Hirono, Ryo Yokokura arXiv: http://arxiv.org/abs/2007.15901v1 Title: Illustrations of non-Euclidean geometry in virtual reality Author: Martin Skrodzki arXiv: http://arxiv.org/abs/2008.01363v1 Title: Search for dark matter signals towards a selection of recently-detected DES dwarf galaxy satellites of the Milky Way with H.E.S.S Author: H.E.S.S. Collaboration arXiv: https://arxiv.org/abs/2008.00688
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2020-08-06
お知らせ
「『役に立たない』科学が役に立つ」が7月27日に発刊
プリンストン⾼等研究所の創⽴者フレクスナーと現在の所⻑であるダイクラーフによるエッセイ、"Usefulness of Useless Knowledge”の日本語版が、初⽥哲男プログラムディレクターの監訳により「『役に立たない』科学が役に立つ」として東京大学出版会より刊行されました。 日本語版では、豊富な訳注、研究者の解説、コラム記事などを加え、日本の読者にも読みやすいものとなっており、基礎研究の重要性に対する認識が広まる一助になると期待されます。本書の刊行を機に、基礎研究の意義に関してのオンライン座談会が8月22日に開催されます。また、基礎研究の意義を高校生にも理解してもらうために、全国のSSH指定校を対象に本書を寄贈します。
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2020-08-05
セミナーレポート
Biology Seminar by Dr. Lukasz Kusmierz on August 5, 2020
On 5th August, Ph.D. Lukasz Kusmierz ( RIKEN Center for Brain Science ) gave a talk at the iTHEMS Biology Seminar. Dr. Kusmierz introduced us to his work that modeling of heavy tails in the distribution of synaptic weights in the brain. His modeling, called "Cauchy network" which is based on the Cauchy distribution, has been successful in recreating biologically distributions. It could serve as a useful framework for checking the effects of synaptic heavy tails in various scenarios. His research will be a major step forward in the future of neuroscience. Thank you very much, Lukasz!
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2020-08-05
セミナーレポート
Math Seminar by Dr. Tadahiro Miyao
The iTHEMS Math seminar entitled "Stability of ferromagnetism in many-electron systems”, by Dr. Tadahiro Miyao, was held on 31 July. In the first part, the speaker reviewed basic properties of electron and introduced the Hubbard model, which describes interacting electrons. In addition, he constructed a model independent framework describing stabilities of ferromagnetism in strongly correlated electron systems. Especially, he reinterpreted the famous Marshall-Lieb-Mattis theorem and Lieb’s theorem. Then he showed that Lieb’s theorem still holds true even if the electron-phonon and electron-photon interactions are taken into account. As examples, he explained the Holstein-Hubbard model and the Kondo lattice model. Finally, he also mentioned other stability classes and open problems. In the second part, the speaker introduced order preserving operator inequalities and many mathematical tools, such as the Perron-Frobenius-Faris theorem, abstract reflection positivity, the hole-particle transformation, and so on. He also explained how these inequalities are applied to the mathematical study of ferromagnetism. Then Lieb's theorem of the Hubbard model and its stabilities were discussed in terms of the inequalities.
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2020-08-03
プレスリリース
「初田哲男×大隅良典×隠岐さや香 オンライン座談会 -『役に立たない』科学が役に立つ」を8/22に開催！
アカデミスト株式会社（本社：東京都新宿区、代表取締役CEO：柴藤亮介、以下アカデミスト）と理化学研究所数理創造プログラム（所在地：埼玉県和光市、プログラムディレクター：初田哲男、以下iTHEMS）は、2020年8月22日（土）13時より「初田哲男×大隅良典×隠岐さや香 オンライン座談会 -「役に立たない」科学が役に立つ」を共同開催いたします。
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2020-08-03
今週の注目人物
Self-introduction: Ching-Kai Chiu
Hello, I will officially join iTHEMS on August 1st as a senior research scientist. My name is Ching-Kai Chiu from Taiwan, and I am a condensed matter physicist. Unfortunately, I cannot enter Japan now due to the travel restriction. Hopefully, I can see everyone in person after COVID-19. Please feel to contact me anytime. My research interests are topological states of matter, superconductivity, and quantum computing. Specifically, my works are related to topological insulators, semimetals, superconductors, and non-Hermitian systems, as well as the designing of universal quantum computers. I have enjoyed using mathematics to explore condensed matter physics and collaborating with theorists and experimentalists. However, I don’t want to limit myself in condensed matter physics. I have broad interests in science. When I was in graduate school (the University of Illinois at Urbana-Champaign), I learned general relativity (Sean Caroll’s and Wheeler’s books) and field theory. Recently, I am also interested in (quantum) cryptography and cryptocurrency. It is exciting for me to work in iTHEMS to interact with scientists from different fields. About my personal life, I lived in many countries, such as USA, Canada, Taiwan, Germany, China. I have enjoyed nature and visited around 20 national parks in the United States. You name it. Yellowstone, Yosemite, and Mount Rainier. My wife and I like to travel. We have been at least 25 countries before COVID-19. My favorite habits are rock climbing and playing board games, such as Terraforming Mars and Power Grids.
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2020-07-31
セミナーレポート
Biology Seminar by Dr. Takashi Okada on July 29, 2020
On 29th July, Takashi Okada gave us a talk on his work on population genetics theory. He first explained that the classical Wright-Fisher demography cannot inherently consider the realistic situation in which the offspring-number distribution is skewed. Second, he talked about what if we extend the Wright-Fisher demography to a skewed offspring number (power low distribution), showing us that the power-low distribution can dramatically change the timescale of evolution (e.g., sojourn time of fixation of a neutral mutant) as well as large population size limits. We learned that even the classic theory arising from Sewall Wright and Ronald A Fisher entails mathematical expansion. Thank you so much, Takashi, for the great talk!
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2020-07-30
今週の論文Week 4 & 5 of July
Title: Community analysis of inter-firm networks with graph convolutional networks Author: Shunsuke Ohkoda, Yasuhiro Yamaguchi, Takeru Nitta, Yoshimasa Hidaka, Takahiro Doi, Masaki Yanaoka, Atsushi Takemasa doi: 10.11517/pjsai.JSAI2020.0_1N5GS1301 Title: Performance correlation analysis of business-to-business transactions and its application to corporate growth forecast Author: Takahiro Doi, Shunsuke Ohkoda, Takeru Nitta, Yoshimasa Hidaka, Yasuhiro Yamaguchi, Masaki Yanaoka, Atsushi Takemasa doi: 10.11517/pjsai.JSAI2020.0_1N4GS1305 Title: Dynamics of interfirm trading network based on multi-agents based model Author: oshimasa Hidaka, Shunsuke Ohkoda, Takeru Nitta, Takahiro Doi, Yasuhiro Yamaguchi, Masaki Yanaoka, Atsushi Takemasa doi: 10.11517/pjsai.JSAI2020.0_4G3GS701 Title: X-ray Hotspots in the Northwest Shell of the Supernova Remnant RX J1713.7−3946 Author: Ryota Higurashi, Naomi Tsuji, Yasunobu Uchiyama arXiv: 2006.15796 Title: Resolving acceleration to very high energies along the Jet of Centaurus A Author: The H.E.S.S. Collaboration, Tsuji, N doi: 10.1038/s41586-020-2354-1 arXiv: 2007.04823 Title: Improved thermal area law and quasi-linear time algorithm for quantum Gibbs states Author: Tomotaka Kuwahara, Álvaro M. Alhambra, Anurag Anshu arXiv: http://arxiv.org/abs/2007.11174v1 Title: Dirichlet Series with Periodic Coefficients and their Value-Distribution Near the Critical Line Author: Athanasios Sourmelidis, Jörn Steuding, Ade Irma Suriajaya arXiv: http://arxiv.org/abs/2007.14008v1
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2020-07-27
セミナーレポート
Special DMWG seminar : The latest results from the XENON1T experiment
XENON1T collaboration has reported interesting results in June, which could be the signature of the physics beyond the standard model. We held a special DMWG seminar on July 22, inviting Prof. Yamashita, who is a specialist in the XENON1T data analysis, from Nagoya University. Many people from various research fields have registered and participated in this online seminar. The number of registrants is more than 180 while the participants than 100. We first would like to apologize to our guests, especially to whom could not attend the seminar although they have registered due to our trouble with the webinar system. XENON1T is an experiment aiming to detect the scattering between dark matter (DM) and a xenon nucleus. Xenon is one of the best targets material for WIMP (Weakly Interacting Massive Particle) because of its stability and the large atomic number. By setting the detector deep underground, the cosmic-ray scattering event, which is the main source of the background, is efficiently removed. The original experiment was started in 2005 (XENON10) and after several upgrades, XENON1T has completed its first observing run in 2018. The signature of the so-called nuclear recoil event is searched to detect WIMP. There is another type of event referred to as the electronic recoil event, which is also useful to detect other DM signatures, and this seminar focuses on such a kind of event. The target region of the DM parameter space is different between these two event types. The 285 electronic recoil events over the expected 217-247 from the background are observed in the recoil energy range of 1-7keV during the 1st observing run of the XENON1T experiment. In this talk, Prof. Yamashita has explained the details of the analysis and the possible interpretation of the signature. Starting from the introductions about the possible background considered in the traditional analysis, the statistical treatments, and also the model fitting results are provided. There are several possibilities for explaining the excess: (i) tritium background, (ii) solar axion, (iii) anomalous neutrino magnetic moment, and (iv) bosonic DM. If the excess is explained by tritium (i), it means that we have detected the first tritium background events while others indicate the detection of the signatures of the new physics. Solar axion (ii) could fit the recoil spectrum beautifully, however, there may not be consistent with the results from astrophysical observations. The neutrino scenario (iii) is another possibility with less significance, and the significance of the bosonic DM scenario (iv) could not over the 3.0 sigma. The excess itself is convincing while it is difficult to conclude its origin. Abobe-mentioned possibilities are planned to be tested with further upgrades of the XENON1T experiment, XENONnT. We should be excited about the results in the near future. Stay tuned!
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2020-07-27
ホットトピックiTHEMS Science Outreach Workshop 2020 was held on July 3 and 4
On July 3 and 4, we had Journalist in Residence Workshop 2020 on Zoom. It had been planned to be held at Tambara Institute of Mathematical Sciences of the University of Tokyo as in a same way as May 31 - June 3 of the last year 2019. This year, Tambara Institute is closed because of COVID-19 but we organized it on Zoom. There were in fact much more participants than last year and those living in US also participated in the meeting. The participants included 14 journalists and 17 participants from RIKEN, 9 from universities and 2 from others. 7 iTHEMS members mainly explained their working field and recent important achievements to the nonspecialists. There were 24 talks in total in a variety of fields. The discussion among the participants continued with joy in the evening of July 3 even in ZOOM. If we organize next year, it will be necessary to include online participants.
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2020-07-20
セミナーレポート
Math seminar by Dr. Yuichi Ike on July 15, 2020
We have all heard that "data is the new oil". But just like any fossil resource, data also has to be worked with to use it effectively. In his talk, titled "Topological data analysis from a practical and mathematical perspective", Dr. Yuichi Ike from Fujitsu highlighted several mathematical aspects of data processing as well as relevant applications in the health sector. In the first part of the talk, the audience was introduced to basic concepts of topological data analysis. The goal of this technique is to infer the shape of data - i.e. topological quantities such as the number of connected components, loops, cavities, etc. - from the input data points. While the shape is represented by the homology group in the continuous case, the discrete case calls for different methodology. One possible technique is the creation of persistence diagrams to identify critical components. In a general application workflow, these approaches appear as follows. From the input data, its persistent homology is computed, visualized via a persistence diagram, and finally passed on to experts for evaluation. This has applications in material sciences and time series analysis as well as medical settings. Here, a recent work of the speaker was able to reduce misclassifications in a diagnosis setting by up to 70%. The second part of the talk was devoted to the mathematical foundations of the presented work, namely on persistence-like distance on the sheaf category and displacement energy. Starting from elements in symplectic geometry, via a Morse theory for sheaves, the speaker integrated several mathematical fields. Finally, after introducing the non-displacement theorem, the audience learned about several proofs in the field. Thus, the talk nicely tied current relevant applications to deep results in theoretical mathematics.
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2020-07-16
セミナーレポート
Biology Seminar about "Application of geometry to protein structure analysis" on July 15, 2020
In Biology Seminar on 15th July, a graduate student Haru Oono-Negami (Engineering department, University of Tokyo) talked about a general overview of the interdisciplinary topic between geometry and protein biology, as well as her own work on the protein-classification algorithms based on topological properties. Understanding and predicting the function of structurally "similar" proteins is of pivotal importance to any field of biology. Her work extends previous studies that classify the topological structure of proteins in a computationally reasonable time still with a good accuracy. We audience, after her talk, excitedly discussed extensions and background problems behind her talk. Thank you so much for the great talk, Haru-san! - Ryosuke Iritani
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2020-07-16
セミナーレポート
DMWG seminar on July 13 by Dr. Michimura
The Michelson interferometer is sensitive to the new physics as well as to the gravitational wave. The input laser beam is split in the horizontal and vertical direction, then combined again after times of the round trip in the cavity of each path. The patters of the interference give us the information about the change in path length, forces shifting the reflecting mirrors, and/or the change in the speed of light. During the observing run searching for the gravitational waves, a high-intensity laser form the input source is supplied continuously so it is highly efficient if we can make use of the laser to probe other physics simultaneously. Let us focus on the laser beams after the split. The polarization of the split laser beam changes at each time it is reflected. When axion (or axion-like particle, ALP) coupled to photon exists, the velocity of the right- and left-handed polarized waves should be different. Hence by setting the "bow-tie" cavity to realize different path-length for the right- and left-handed polarized photons, we should see the signature of the ALP in the interference pattern. This idea, which is proposed by Dr. Michimura and his colleagues, is completely new and enable us to probe the unexplored region for ALP lighter than ~0.1 micro-eV. Furthermore, this new search can be done during the gravitational-wave observations and do not affect such observations. He also has shown the expected sensitivity for scalar and vector DM picking up well-motivated examples and told us another idea for the experiment. Such new ideas should open new ways to access the nature of dark matter!
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2020-07-10
プレスリリース
自然界の「ムダの進化」が生物多様性を支える －生物種の個体数増加に寄与しない利己的な性質の進化が導く多種共存－
生物の装飾や求愛行動などの適応的特徴の進化は、その個体にとっては有利でも、種全体の増殖率への貢献は期待できないことから、種の繁栄にとっては、いうなれば「ムダの進化」です。東北大学大学院生命科学研究科の近藤教授、クイーンズランド大学 山道上級講師のほか、兵庫県立人と自然の博物館、理化学研究所数理創造プログラム、京都大学、千葉大学、琉球大学、弘前大学、東京大学の研究者からなる共同研究グループは、この「ムダの進化」こそが、自然界で競争排除を生じにくくしている要因である可能性を理論的に示しました。本研究では、これまで生物多様性との関係が省みられることのなかった要因が、種多様性の維持にとって重要であることを明らかにしたという斬新な成果を得ました。
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2020-07-09
今週の論文Week 2 of July
Title: Constraining Primordial Black Holes with Dwarf Galaxy Heating Author: Philip Lu, Volodymyr Takhistov, Graciela B. Gelmini, Kohei Hayashi, Yoshiyuki Inoue, Alexander Kusenko arXiv: http://arxiv.org/abs/2007.02213v1 Title: On origami embeddings of flat tori Author: Takashi Tsuboi arXiv: http://arxiv.org/abs/2007.03434v1
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2020-07-09
プレスリリース
蒸発するブラックホールの内部を理論的に記述
理化学研究所（理研）数理創造プログラムの横倉祐貴上級研究員らの共同研究チームは、量子力学と一般相対性理論を用いて、蒸発するブラックホールの内部を理論的に記述しました。 本研究成果は、ブラックホールの正体に迫るものであり、遠い未来、情報を蓄えるデバイスとしてブラックホールを活用する「ブラックホール工学」の基礎理論になると期待できます。 本研究は、オンライン科学雑誌『Universe』（6月4日付）に掲載されました。
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2020-07-08
セミナーレポート
Biology Seminar by Dr. Yui Uchida on July 8, 2020
On 8th July, Ph.D. Yui Uchida (RIKEN BDR) gave a talk at the iTHEMS Biology Seminar. Dr. Uchida introduced to us the research field of Evolutionary Developmentary biology (EvoDevo) and talked about her researches on embryogenesis. Her lecture gave a briefly explanation about the background of EvdDevo in general and the important evolutionary questions in vertebrate development that had been tackled by her with mathematical modeling of embryogenesis. I felt her lecture helped many audiences to understand EvoDevo and we had a good discussion. Another highlight of her talk was her talk on the evolution of the five fingers of Tetrapoda excited the physicists! Thank you very much, Dr. Uchida.
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2020-07-02
今週の論文Week 1 of July
Title: Higher-form symmetries and 3-group in axion electrodynamics Author: Yoshimasa Hidaka, Muneto Nitta, Ryo Yokokura arXiv: http://arxiv.org/abs/2006.12532v1 Title: Monte-Carlo simulations of fast Newtonian and mildly relativistic shock breakout from a stellar wind Author: Hirotaka Ito, Amir Levinson, Ehud Nakar arXiv: http://arxiv.org/abs/2006.14250v1 Title: The classification of symmetry protected topological phases of one-dimensional fermion systems Author: Chris Bourne, Yoshiko Ogata arXiv: http://arxiv.org/abs/2006.15232v1 Title: Microscopic theory of the fluctuating hydrodynamics in nonlinear lattices Author: Keiji Saito, Masaru Hongo, Abhishek Dhar, Shin-ichi Sasa arXiv: http://arxiv.org/abs/2006.15570v1 Title: Griffiths-McCoy singularity on the diluted Chimera graph: Monte Carlo simulations and experiments on the quantum hardware Author: Kohji Nishimura, Hidetoshi Nishimori, Helmut G. Katzgraber arXiv: http://arxiv.org/abs/2006.16219v1 Title: Experimental visually-guided investigation of sub-structures in three-dimensional Turing-like patterns Author: Martin Skrodzki, Ulrich Reitebuch, Eric Zimmermann arXiv: http://arxiv.org/abs/2006.16676v1 Title: Stealth dark matter confinement transition and gravitational waves Author: R. C. Brower, K. Cushman, G. T. Fleming, A. Gasbarro, A. Hasenfratz, X. Y. Jin, G. D. Kribs, E. T. Neil, J. C. Osborn, C. Rebbi, E. Rinaldi, D. Schaich, P. Vranas, O. Witzel arXiv: http://arxiv.org/abs/2006.16429v1
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2020-07-02
セミナーレポート
Biology Seminar by Dr. Shingo Gibo on July 1, 2020
On 1 July, Shingo Gibo gave a talk at the iTHEMS Biology Seminar. He talked about his research on using mathematical approaches to understand biological oscillations, such as circadian rhythms. His work is a really nice example of the synergy between different disciplines. He draws ideas from mathematics and physics to solve problems in life science, and then his results developed in life science feeds back to various areas related to mathematics and physics. Another highlight of his talk was his cute zoom background :-) -Jeffrey Fawcett
187件のニュース / 2020年