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

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!

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.

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.

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

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

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

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

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

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