# Event Schedule

## Events for the 4th week of April 2021

2021-04-15

The iTHEMS x academist online open to the public "Mathematical Science World" and the MACS Colloquium are scheduled for next week.

Sunday, April 18, 10:00- iTHEMS x academist Online open to the public "Mathematical science world"

Thursday, April 22, 10:00- iTHEMS Biology Seminar

Friday, April 23, 12:30- Coffee Meeting

Friday, April 23, 15:00- MACS Colloquium

# Book

## The Future of 'Useless' Research

2021-04-14

Authors: Tetsuo Hatsuda, Yoshinori Ohsumi and Sayaka Oki

Editor: Ryosuke Shibato

Language: Japanese

What is "useful"? What does it mean to "study"?

Thinking about science, budget, and our future with researchers on the front lines!

- The Future of 'Useless' Research | KASHIWASHOBO (in Japanese)
- The Future of 'Useless' Research | Amazon (in Japanese)
- Event: Is there a wall between "citizens" and "researchers"? | KASHIWASHOBO | note (in Japanese)
- Interview: Is 'Useless' Research and Study Unnecessary? The Historical Background and Future of Research (Ichishi Iida) | Gendai Business | KODANSHA (in Japanese)
- Review: "The Future of 'Useless' Research" Who Decides That? | HONZ (in Japanese)
- Selected as a summer vacation book: The 54th Summer Vacation Book | School Library Association (in Japanese)
- Review: The "Useless" Work Style | Otaki Binta | note (in Japanese)
- Review: Recommended for high school students seeking a career path | University News | note (in Japanese)
- Review: Moving Away from the Shackles of "Useless" | IDE Contemporary Higher Education | note (in Japanese)

# Book

## Deep Learning and Physics

2021-04-14

Author: Akinori Tanaka, Akio Tomiya and Koji Hashimoto

Language: English

Is the first machine learning textbook written by physicists so that physicists and undergraduates can learn easily. Presents applications to physics problems written so that readers can soon imagine how machine learning is to be used. Offers the starting point for researchers in the rapidly growing field of physics and machine learning.

# Hot Topic

## iTHEMS Starter Meeting for FY 2021 on April 9, 2021

2021-04-15

iTHEMS officially kicked off its activity for FY 2021 by the iTHEMS Starter Meeting for FY 2021, on April 9th 2021. The meeting was held over Zoom as last year's meeting. Over sixty iTHEMS members gathered together as well as several frequent visitors and colleagues from other institute, and introduced themselves to other members.

# Seminar Report

## Quantum Matter Seminar by Dr. Mario Flory on April 14, 2021

2021-04-16

On April 14th, from Instituto de Física Teórica, Universidad Autonoma de Madrid and Consejo Superior de Investigaciones Científicas, in Spain, Dr. Mario Flory gave a seminar talk about the connection between the AdS/CFT correspondence and condensed matter physics.

In the first half of the talk, he briefly reviewed the ideas of the correspondence and its history. The most important breakthrough is that Juan Maldacena first proposed the AdS/CFT in the late '90s. It is known that the entropy of the black hole is proportional to its area, so that this feature suggests a holographic principle. The AdS/CFT correspondence serves a better understanding of this principle by connecting strongly coupled CFTs to classical gravity.

In the second half, Dr. Flory addresses the important application of the correspondence to condensed matter physics. Because of the AdS/CFT correspondence, the problems of the Kondo model in condensed matter physics can be tackled by solving gravity problems. He specifically discussed the entanglement problem through the correspondence in detail. We thank Dr. Flory for giving an excellent talk.

Reported by Thore Posske (University of Hamburg, Germany) and Ching-Kai Chiu

What "Holography" is and how to use it

April 14 at 17:00 - 18:15, 2021

# Seminar Report

## iTHEMS Biology Seminar by Dr. Kyosuke Adachi on April 15, 2021

2021-04-15

In iTHEMS Biology Seminar on April 15th, Kyosuke Adachi (BDR/iTHEMS) talked about the formation mechanism and the biological function of liquid condensates in eucaryotic cell. First, he explained the higher-order structure of the chromatin fiber. He focused on A compartment and B compartment, in which the high and low transcription activities are shown, respectively. Then, he talked about the biomolecular condensate which is the liquid droplet composed of proteins. He talked about the important interaction on the condensate creation and explained the theoretical model based on the mean field theory. Finally, he explained the role of the condensates on the transcription activity. The transcription occurs in the condensates of some proteins coexisting on the chromatin fiber. The audience enjoyed his attractive talk. Thank you very much for great talk, Kyosuke!

Reported by Hiroshi Yokota

Liquid condensates in cell nucleus

April 15 at 10:00 - 11:00, 2021

# Seminar Report

## iTHEMS Biology Seminar by Prof. Catherine Beauchemin on April 8, 2021

2021-04-15

In iTHEMS Biology Seminar on April 8th, Catherine Beauchemin (Deputy Program Director of RIKEN iTHEMS and Professor of Ryerson University) gave us an introductory talk on Markov chain Monte Carlo (MCMC) method. Many of theoretical scientists often use mathematical models, but it is difficult to correctly estimate parameter values of the model from experimental data. In this seminar, Catherine taught us the MCMC method is a powerful tool for parameter estimation using her recent research on cancer as an example. First, she explained four simple models of cancer growth. Then, using these models, she explained the basic idea and the detail process of the MCMC method. Her talk was very clear. I think that the seminar became helpful for the many attendees because the method can be applied to various fields of science and engineering. Merci beaucoup, Catherine!

Reported by Shingo Gibo

Simple models of cancer growth, MCMC parameter estimation and identifiability

April 8 at 10:00 - 11:00, 2021

# Seminar Report

## Journal Club of Information Theory SG by Dr. Yukimi Goto on April 14, 2021

2021-04-15

On 14th April, Dr. Yukimi Goto gave an introduction to trace inequalities and related topics in our journal club of the Information Theory Study Group. She started from a simple counter example of the triangle inequality for operators on Hilbert space, and introduced density matrices, von Neumann entropy and Wigner-Yanase skew information. Then, she explained the concept of jointly convex/concave functions and Wigner-Yanase-Dyson-Lieb theorem, and discussed the sub-additivity and strong sub-additivity of von Neumann entropy and its generalizations. Thank you, Goto-san, for interesting talk!

Reported by Akinori Tanaka

Journal Club: Trace inequalities and their applications

April 14 at 14:30 - 15:30, 2021

# Seminar Report

## Math Seminar by Dr. Kai Koike on April 7, 2021

2021-04-12

On April 7, Dr. Kai Koike from Kyoto University gave a talk entitled “Long-time behavior of moving solids in a fluid and the kinetic theory of gases” at Math seminar.

In the first part, he reviewed a moving boundary problem of gases. Then he introduced some interesting results in fluid dynamics and developments concerning his research.

In the second part, the speaker explained his results about the long-time behavior of a point particle moving in a fluid. It is an explanation of related numerical results for a BGK model of the Boltzmann equation.

Reported by Yukimi Goto

Long-time behavior of moving solids in a fluid and the kinetic theory of gases

April 7 at 16:00 - 18:10, 2021

# Upcoming Events

## 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

## Special Lecture

### iTHEMS x academist online open to the public "Mathematical Science World 2021"

April 18 at 10:00 - 16:30, 2021

Dr. Kanato Goto (Special Postdoctoral Researcher, iTHEMS)

Dr. Jeffrey Fawcett (Senior Research Scientist, iTHEMS)

Dr. Takuya Sugiura (Postdoctoral Researcher, iTHEMS)

Dr. Naomi Tsuji (Postdoctoral Researcher, iTHEMS)

Dr. Keita Mikami (Research Scientist, iTHEMS)

Dr. Tetsuo Hatsuda (Program Director, iTHEMS)

Venue: via Zoom

Event Official Language: Japanese

## Seminar

### The rheotaxis mechanism of swimming ciliates

April 22 at 10:00 - 11:00, 2021

Dr. Yukinori Nishigami (Research Institute for Electronic Science, Hokkaido University)

The swimming unicellular organisms, which live in freshwater, need to resist currents in the environment. Without this ability, their habitat changes with the flow, and they cannot survive in nature for a long time. It is reported that a kind of swimming microorganism, Paramecium, exhibits upstream swimming in 1904. However, the mechanism of the behavior has been still unclear. To elucidate the mechanism, we observed the behavior of a ciliate in a flow field and performed numerical fluid calculations. My results suggest that the rheotaxis is realized by cell shape and inhibition of ciliary beating near the wall.

*Please refer to the email to get access to the Zoom meeting room.

Venue: via Zoom

Event Official Language: English

## Colloquium

### 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

## Seminar

### Thermodynamic Uncertainty Relation Connects Physics, Information Science, and Biology

April 28 at 13:30 - 16:00, 2021

Prof. Yoshihiko Hasegawa (Associate Professor, Department of Information and Communication Engineering, The University of Tokyo)

Higher precision demands more resources. Although this fact is widely accepted, it has only recently been theoretically proved. The thermodynamic uncertainty relation serves as a theoretical basis for this notion, and it states that current fluctuations are bounded from below by thermodynamic costs, such as entropy production and dynamical activity. In this seminar, I show a strong connection between the thermodynamic uncertainty relation and information theory by deriving it through information inequality known as a Cramér-Rao bound, which provides the error bound for any statistical estimator. Moreover, by using a quantum Cramér-Rao bound, I derive a quantum extension of thermodynamic uncertainty relation, which holds for general open quantum systems. The thermodynamic uncertainty relation predicts the fundamental limit of biomolecular processes, and thus it can be applied to infer the entropy production, corresponding to the consumption of adenosine triphosphate, of biological systems in the absence of detailed knowledge about them.

*Detailed information about the seminar refer to the email.

Venue: via Zoom

Event Official Language: English

# Paper of the Week

## Week 3 of April 2021

2021-04-15

Title: Approximate Bayesian Computation of Bézier Simplices

Author: Akinori Tanaka, Akiyoshi Sannai, Ken Kobayashi, Naoki Hamada

arXiv: http://arxiv.org/abs/2104.04679v2

Title: Detailed analysis of excited state systematics in a lattice QCD calculation of $g_A$

Author: Jinchen He, David A. Brantley, Chia Cheng Chang, Ivan Chernyshev, Evan Berkowitz, Dean Howarth, Christopher Körber, Aaron S. Meyer, Henry Monge-Camacho, Enrico Rinaldi, Chris Bouchard, M. A. Clark, Arjun Singh Gambhir, Christopher J. Monahan, Amy Nicholson, Pavlos Vranas, André Walker-Loud

arXiv: http://arxiv.org/abs/2104.05226v1

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