iTHEMS Weekly News Letter

Event Schedule

Events for the 5th week of June 2021


Tuesday, June 29, 13:00- iTHEMS Theoretical Physics Seminar
Thursday, July 1, 10:00- iTHEMS Biology Seminar
Friday, July 2, 12:30- Coffee Meeting
Friday, July 2, 16:00- iTHEMS Math Seminar

Seminar Report

iTHEMS Biology Seminar by Dr. Jeffrey Fawcett on June 10, 2021


On 10 June 2021, our iTHEMS member Jeffrey Fawcett gave a talk about “the origin and dispersal of buckwheat” at the Biology Seminar. Jeffery works on or has worked on a broad range of topics related to genomics, evolution, genetics, bioinformatics, and systems biology. This time, he talked about his recent worldwide collaboration work using genomic data of wild samples from China (around Yunnan, Sichuan, and Tibet) and cultivated samples from various parts of the world to understand “when”, “where”, and “how” buckwheat originated and then spread across the world and came to Japan. He explained the significance of studying "domestication", which can contribute to research on evolution, molecular breeding and implications for human history. Buckwheat, which soba noodles is made from, is now such a familiar everyday life related plant in Japan. We are surprised how such a genomic approach about soba revealed the history of ancient world and Japan and gave us a hint about the origin of Japanese people. We are looking forward to further discovery of this interesting research topic.

Report by Yingying Xu

The origin and dispersal of buckwheat image

Seminar Report

iTHEMS Biology Seminar by Prof. Fumito Mori on June 24, 2021


In iTHEMS biology seminar on June 24, Fumito Mori (Assistant Professor, Faculty of Design, Kyushu University) gave us a talk on synchronization and variability of the periodicity. In the seminar, he introduced minimal models of coupled oscillators to discuss synchronization. Interestingly, the variability of the periodicity, in general, depends on which variables (or genes) we consider and on which timepoints we (or cells) measure the periodicity.
He demonstrated this subtlety in the so-called repressilator system. He then discussed how noise and interaction parameters can be inferred from given data of periodicity. In the talk, he showed us many general results, which were very impressive to us. Finally, I am grateful to Mori-san because I asked him to do the seminar just two weeks before it, but he kindly accepted. Thank you very much for the fantastic talk, Mori-san!

Reported by Takashi Okada

Upcoming Events

External Event

Dr. Akinori Tanaka thumbnail

RIKEN Day: Let's Talk with Researchers! "Can Artificial Intelligence Draw Pictures?"

June 25 at 18:00 - 18:30, 2021

Dr. Akinori Tanaka (Senior Research Scientist, iTHEMS)

In the June RIKEN Day, we will have a talk with Akinori Tanaka, a researcher who is researching on the theme of "Can Artificial Intelligence Draw Pictures?"

See related links for details.

Venue: via Zoom

Event Official Language: Japanese


iTHEMS Theoretical Physics Seminar

Toward QCD-based description of dense baryonic matter

June 29 at 13:00 - 14:30, 2021

Dr. Yuki Fujimoto (The University of Tokyo)

The equation of state (EoS) of dense baryonic/quark matter is the crucial ingredient for understanding neutron stars. I briefly review the current state of the high-density matter EoS based on the QCD perspectives. In this talk, I particularly focus on the perturbative QCD (pQCD) EoS, which was previously thought to be useless at realistic density because it is plagued by the large uncertainty. I introduce our recent analysis of the EoS calculated within the pQCD framework with the resummation [Fujimoto & Fukushima, 2011.10891]. I discuss our scheme for the Hard Dense Loop resummation, which turns out to reduce the uncertainty compared with the conventional pQCD estimate without resummation. Our result apparently extends the applicability of the QCD-based EoS down to densities realized inside neutron stars and infers a smooth matching with the baryonic EoS.

Venue: via Zoom

Event Official Language: English


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iTHEMS Biology Seminar

How nucleus size affects chromatin motion? - Experimental measurements and a polymer physics theory

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

Prof. Takahiro Sakaue (Associate Professor, College of Science and Engineering, Department of Physics and Mathematics, Aoyama Gakuin University)

Chromatin moves dynamically inside the cell nucleus, and its motion is often correlated with gene functions such as DNA recombination and transcription. A recent study has shown that during early embryogenesis of the nematode, Caenorhabditis elegans, the chromatin motion markedly decreases with the cell stage. However, the underlying mechanism for this transition has yet to be elucidated. Here we systematically investigate the impact of nuclear size to demonstrate that it is indeed a decisive factor in chromatin mobility. We show that a simple theoretical description, which takes into account the length and time scales of chromatin polymer solution, can quantitatively describe the relationship between the nucleus size and the chromatin motion in vivo. Our results emphasize a regulatory role of nuclear size in restricting chromatin motion, and a generic polymer physics model plays a guiding role in capturing this essential feature.

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

Venue: via Zoom

Event Official Language: English


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iTHEMS Math Seminar

An introduction to modular functions, conformal field theories, and moonshine phenomena

July 2 at 16:00 - 18:10, 2021

Mr. Mizuki Oikawa (Junior Research Associate, iTHEMS / Student Trainee, iTHEMS / Ph.D. Student, Graduate School of Mathematical Sciences, The University of Tokyo)

Moonshine phenomena are certain mysterious connections between modular functions and finite groups. The first example is the celebrated monstrous moonshine, which connects the J-invariant and the Monster group. Surprisingly, this relationship can be well understood in terms of chiral conformal field theory. In this talk, I would like to explain what is chiral conformal field theory and how it gives moonshine phenomena.
In the first part of the talk, the notion of modular function will be introduced and the precise statement of the monstrous moonshine will be given. Then the monstrous moonshine will be explained in terms of vertex operator algebra, a mathematical model of chiral conformal field theory.
In the second part of the talk, we focus on the question: what is chiral conformal field theory mathematically? In addition to vertex operator algebras, other mathematical models of chiral conformal field theory, namely conformal nets and Segal conformal field theories, will be introduced. Recent progress on the relationship among these three models, including the Carpi--Kawahigashi--Longo--Weiner correspondence and the geometric realization of conformal nets will also be reviewed.

Venue: via Zoom

Event Official Language: English


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MACS ColloquiumCo-hosted by iTHEMSSUURI-COOL (Kyoto)

The 16th MACS Colloquium

July 5 at 15:00 - 18:00, 2021

Prof. Yoshitaka Tanimura (Professor, Department of Biophysics, Kyoto University, Graduate School of Science)
Prof. Hidetoshi Nishimori (Senior Visiting Scientist, iTHEMS / Specially Appointed Professor, Tokyo Institute of Technology)

15:00- Talk by Prof. Yoshitaka Tanimura
16:15- Talk by Prof. Hidetoshi Nishimori
17:15- Discussion

Venue: via Zoom

Event Official Language: English


iTHEMS Colloquium

Quantitative Population Dynamics in Interdisciplinary Biology

July 8 at 10:30 - 12:00, 2021

Prof. Shingo Iwami (Professor, Division of Biological Science, Graduate School of Science, Nagoya University)

Through the course of life, from the moment of birth till death, an organism will achieve various states of equilibrium or ‘homeostasis’ which will inevitably encounter perturbations. The processes of cell growth, differentiation, infection, mutation, evolution and adaptation work together as a coordinated ‘system’, described by mathematical models for population dynamics, to maintain a healthy state. Any disruptions to this system leads to disease including infection, allergy, cancer, and aging. We are conducting interdisciplinary research to elucidate “Quantitative Population Dynamics” through the course of life with original mathematical theory and computational simulation, which are both our CORE approach. Our mathematical model-based approach has quantitatively improved a current gold-standard approach essentially relying on the statistical analysis of “snapshot data” during dynamic interaction processes in life sciences research. In this talk, I will explain how our interdisciplinary approach extends our understanding for complicated clinical data and apply real world problem with an example of the Novel Coronavirus Disease, COVID-19.

Venue: via Zoom

Event Official Language: English


iTHEMS Science Outreach Workshop 2021

July 11 - 12, 2021

RIKEN iTHEMS, an interdisciplinary Theoretical and Mathematical Sciences Program (RIKEN iTHEMS), was established in November 2016. RIKEN iTHEMS aims to use interdisciplinary methods with a focus on mathematics to elucidate the universe, matter and life, and to solve fundamental problems in society. Building on the achievements of the past exchanges through the Journalist in Residence Program, we will hold an outreach workshop to explore the relevance of the research of the RIKEN iTHEMS to society and to discuss how to build interactive relationships between journalists and researchers in the future. Like last year, this year's workshop will be held as a ZOOM workshop as the seminar house is closed.

Contact: Takashi Tsuboi (iTHEMS Deputy Director)

Venue: via Zoom

Event Official Language: Japanese

Upcoming Visitor

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July 1 - 5, 2021

Dr. Nagisa Hiroshima

Visiting Scientist, iTHEMS / Assistant Professor, Theoretical Physics Group, University of Toyama

Research fields: Dark Matter, High Energy Astrophysics

Visiting Place: RIKEN Wako Campus

Paper of the Week

Week 4, June 2021


Title: XRP Network and Proposal of Flow Index
Author: Hideaki Aoyama

Title: Holographic moving mirrors
Author: Ibrahim Akal, Yuya Kusuki, Noburo Shiba, Tadashi Takayanagi, Zixia Wei

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