iTHEMS Weekly News Letter

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Dr. Tetsuo Hatsuda thumbnail

Message from the Director at the end of FY2020


I would like to thank all the iTHEMS members and iTHEMS supporting staff for your great efforts to keep iTHEMS very active during FY2020 even under the Covid-19. Our iTHEMS mission is very simple. Good science under the environment of interdisciplinary interactions: "A+B --> A*, A+ B --> B*, A+B --> C" are all in line with this mission. We will have many newcomers joining iTHEMS from FY2021, and let us keep moving forward without boundaries.

Now, I would like to congratulate the two iTHEMS students: Toshihiro Ota (student trainee from Osaka Univ.) and Keisuke Fujii (student trainee from Tokyo Institute of Technology) who successfully defended their Ph.D. and are going to graduate from their Universities and from iTHEMS. I hope you have enjoyed your stay in iTHEMS and let us keep in touch for further interactions.

Last but not the least, I would like to thank our assistant Izumi Nagasawa who has made tremendous support for the web page, seminars, colloquiums etc and is leaving iTHEMS at the end of this March. Although we could not see her so frequently in person under Covid-19 situation, she has been really helping our activities from behind. We send her our heartfelt gratitude.


Dr. Takumi Doi thumbnail

Dr. Takumi Doi receives 12th annual RIKEN Research Incentive Award


Takumi Doi (iTHEMS Senior Research Scientist (concurrent)) received "FY2020 Researcher Incentive Award" on March 17, 2021 for his recent paper; Possible lightest Ξ Hypernucleus with Modern ΞN Interactions, published in Phys. Rev. Lett. 124, 092501(1-5) (2020), and related works. Congratulations !


Dr. Masaomi Ono receives 12th annual RIKEN Research Incentive Award


Masaomi Ono (iTHEMS Research Scientist (concurrent)) received "FY2020 Researcher Incentive Award" on March 17, 2021 for his recent paper; Matter Mixing in Aspherical Core-collapse Supernovae: Three-dimensional Simulations with Single-Star and Binary Merger Progenitor Models for SN 1987A, published in The Astrophysical Journal, 888, 111 (2020), and related works. Congratulations !

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Exhibition of "Black Hole Recorder"


At the National Museum of Emerging Science and Innovation (Miraikan) located in Tokyo, iTHEMS exhibition of "Black Hole Recorder" was held last week (March 14-15, March 17-21).

Details of this outreach activity (Black Hole Recorder) and the general concept behind (UselessPrototyping Studio) can be seen from the URLs below.

Seminar Report

Information Theory SG by Dr. Akinori Tanaka on March 24, 2021


On 24th March, Dr. Akinori Tanaka gave an introduction to the reinforcement learning (RL) in our journal club of the Information Theory Study Group. He started from simple examples of a maze and a chess game to introduce the fundamental variables (i.e., states, actions, and rewards) and their evolution as a Markov decision process.After explaining that the goal of the RL is to maximize the value function, he discussed policy improvement theorem with the application to the epsilon-greedy update. We thank Akinori for the great and clear talk!

Journal Club: Reinforcement Learning image

Upcoming Events


Prof. Yoh Iwasa thumbnail

Symposium in Commemoration of Professor Iwasa's Retirement

March 26 at 16:30 - 17:30, 2021

Prof. Yoh Iwasa (Senior Advisor, iTHEMS / Professor, Kwansei Gakuin University)

16:30 - 17:30
"Biology and Mathematical Modeling --- A Report on Fun Days at Kobe Mita Campus
Prof. Yoh Iwasa (School of Science and Technology, Kwansei Gakuin University)

Venue: via Online

Event Official Language: Japanese


iTHEMS Biology Seminar

Structural reduction of chemical reaction networks based on topology

April 1 at 10:00 - 11:00, 2021

Dr. Yuji Hirono (Assistant Professor, Asia Pacific Center for Theoretical Physics, Republic of Korea)

Chemical reactions form a complex network in living cells and they play vital roles for physiological functions. An amusing question is how the structure of a reaction network is linked to its chemical functionalities. I’ll talk about a method of the reduction of chemical reaction networks, which is convenient for extracting important substructures. Mathematical concepts such as homology and cohomology groups are found to be useful for characterizing the shapes of reaction networks and for tracking the changes of them under reductions. For a given chemical reaction network, we identify topological conditions on its subnetwork, reduction of which preserves the steady state of the remaining part of the network.

Venue: via Zoom

Event Official Language: English


Math-Phys Joint Seminar

Self-adjoint extension in quantum mechanics and non-Rydberg spectra of one-dimensional hydrogen atom

April 13 at 16:00 - 18:10, 2021

Prof. Takuju Zen (Professor, School of Environmental Science and Engineering, Kochi University of Technology)

We offer a beginner’s guide to the functional-analytical techniques in quantum mechanics, and cover its application to the 1D Coulomb problem. It is shown that the wave function at the diverging point of the Coulomb potential is mathematically described by three-parameter family of generalized connection conditions. A scheme is devised to physically implement the generalized conditions, which provides the way to experimentally realize non-Rydberg spectra in 1D Hydrogen atom.

Part 1, Self-adjoint extension of Hilbert space operator
Part 2, 1D Coulomb problem

Venue: via Zoom

Event Official Language: English


iTHEMS Colloquium

Mirror symmetry and KAM theory

April 16 at 13:30 - 15:00, 2021

Prof. Kenji Fukaya (Permanent Member, Simons Center for Geometry and Physics, Stony Brook University, New York, USA)

13:30pm-15:00pm (JST)

Mirror symmetry is a phenomenon discovered in String theory and is much discussed recently in mathematics especially in the field of complex (algebraic) geometry and symplectic geometry. Strominger-Yau-Zaslow found that this phenomenon is closed related to a Lagrangian torus fibration. In an integrable system in Hamiltonian dynamics, the phase space is foliated by Lagrangian tori. I would like to explain a program that the Lagrangian torus fibration found by Strominger-Yau-Zaslow could be regarded as one appearing certain integrable system and KAM theory (which describes a amiltonian dynamics that is a perturbation of an integrable system) could appear in the situation of Mirror symmetry.

Venue: via Zoom

Event Official Language: English


The 15th MACS Colloquium thumbnail

MACS ColloquiumSupported by iTHEMSSUURI-COOL (Kyoto)

The 15th MACS Colloquium

April 23 at 15:00 - 17:30, 2021

Prof. Hiroshi Ishikawa (Professor, Faculty of Science and Engineering, Waseda University)

15:00- Talk by Prof. Hiroshi Ishikawa
16:05- MACS Student Conference FY2021

Venue: via Zoom

Event Official Language: Japanese

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