Coffee Meeting Log
Date  Speaker  Title  Abstract 

2018/04/13  Gilles Ferrand  Demonstration of VR system for RIKEN Open Day  This will serve as a rehearsal for the ABBL booth at RIKEN Open Day. I may start with a short introduction on how it works, and our goals. Then iTHEMS people can try the experience with the guidance of ABBL members. 
2018/05/11  Catherine Beauchemin  Proposed iTHEMS project in virophysics: A web tool to count infectious virus!  I want to propose a fun, simple project for any iTHEMS members to join. The plan is to build a webbased calculation tool which can estimate the concentration of virus in a sample based on some standard measurements. 
2018/05/18  Masato Taki  Arithmetic of Words  Word2Vec, proposed by googlers in 2013, is a nice numerical representation of a set of words. This vectorial representation realizes arithmetic relation between words. I will briefly explain how this representation is constructed, and demonstrate it by using a text of Plato. 
2018/05/25  Wine Meeting



2018/06/01  Tetsuo Hatsuda  Life and death of a neutron  1. What is neutron?
2. How it was born in the Universe. 3. How it survives in the Universe. 4. What is the fate of the neutron? 5. Open questions about the neutron. 
2018/06/08  No Talk 


2018/06/15 


about some misuses of statistics in science. 
2018/06/22  Tsukasa Tada  A perspective on conformal field theory from Hyperbolic geometry 

2018/08/24

Gen Kurosawa

On the unsolved mystery of biological clock


2018/10/10

Ade Irma Suriajaya

A new theorem on rational triangles


2018/10/18

Hiroki Kodama

Positive flat functions cannot be positive forever (via differentiations)


2018/11/08

Mamoru Matsuo (Kavli Institute for Theoretical Sciences, UCAS)

Spin hydrodynamic generation: A new power generation at nanoscale


2018/12/07

Catherine Beauchemin

A physicist's adventure into the field of Ergonomics


2019/01/11

Susumu Inoue

Primordial black hole


2019/01/18

Yukinobu Arata (Cellular Informatics Laboratory, RIKEN)

Stochastic and deterministic controls in ageing process


2019/02/15

Maria Dainotti

GRB Correlations for GRB Cosmology and machinelearning analysis


2019/03/28

Yoshiyuki Inoue

Power of Supermassive Black Hole Jets


2019/05/10

Nagisa Hiroshima

Ingredients of gammaray searches of dark matter in the Universe


2019/05/17

Shunji Matsuura (iQBit)

What is quantum computing?


2019/05/24

Yosuke Mizuno (Frankfurt University)  Introduction to Black Hole Shadow of M87


2019/5/31 



2019/6/14 



2019/6/21  Kohei Kamada (Univ. of Tokyo)  On the impact of the chiral anomaly and chiral magnetic effect in the early Universe 

2019/6/28  Enrico Rinaldi (Quantum Hadron Physics Lab.)  The neutron lifetime puzzle 

2019/7/12 



2019/7/19  Tetsuo Hatsuda (iTHEMS)  Preparation for Advisory Council 

2019/8/2 



2019/8/9  Molodij Guillaume (Weizmann Institute)  From astrophysics to Biophysics and back 

2019/8/23  Eren Mehmet Kıral (API/iTHEMS)  On Sensitivity Conjecture 

2019/8/30  Takahiro Doi (QHP Lab.)  Sign problem in evaluating integral of oscillating function 

2019/9/6  Takemasa Miyoshi (RCCS/iTHEMS)  On Data Assimilation 

2019/9/13 



2019/9/20  Enrico Rinaldi (QHP Lab.)  On Dark Matter 

2019/9/27  Andrew Macpherson (IPMU)  Derived geometry and topological field theory 

2019/10/4 



2019/10/11  Yoshiyuki Inoue (ITHEMS)  Nobel Prize in Physics 2019 

2019/10/18  Shingo Gibo (ITHEMS)  Biological rhythms and waveform 

2019/10/25  Ivan Kostov (Saclay) 


2019/11/1  Pascal Naidon (QHP Lab.)  The Efimov Effect 

2019/11/8  Hajime Sotani (ABBL/iTHEMS) 


2019/11/15  Hirotaka Ito (ABBL)  The photospheric origin of the Yonetoku relation in gammaray bursts 

2019/11/22  Tomoki Ozawa (ITHEMS)  The new SI units 

2019/11/29  Masato Taki (ITHEMS)  Pruning brunches of deep learning 

2019/12/6  Jeffrey Fawcett (ITHEMS) 


2019/12/13  15:30~ Nagisa Hiroshima (ITHEMS)  TBA 

2019/12/20 



2020/1/10  Gen Tatara (CEMS/CPR)  Spintronics: Spin current propagation or susceptibility? 

2020/1/17  Hideshi Ooka (CSRS)  Balancing Thermodynamics and Kinetics to Achieve Maximum Rates in Catalysis 

2020/1/24  Martin Skrodzki (iTHEMS)  Algorithms for point set processes 

2020/1/31  Keita Mikami (iTHEMS)  Report on RIKEN iTHEMS  Berkeley Math Visiting Scholar Program (Lunch Meeting) 

2020/2/7 



2020/2/14  Hiroki Kodama (iTHEMS/AIMR)  On the geodesics of regular polyhedra 

2020/2/21  Shane Kelly (Tokyo Institute of Technology)  Motivic homotopy theory and modular representation theory 

2020/3/6 



2020/3/13 



2020/3/20 



2020/3/27  Takemasa Miyoshi (RCCS/iTHEMS) 

(common room w/virtual) 
2020/4/3  Haoning He (ABBL)  Multimeesenger Search for sources of high energy neutrino  (full virtual start) 
2020/4/10  Starter Meeting 


2020/4/17  Pascal Naidon  On COVID19 spreading 

2020/4/24  Ryusuke Hamazaki (Hakubi TL / iTHEMS)  Quantum physicists now study nonHermiticity 

2020/5/1 



2020/5/8  Ryosuke Iritani (iTHEMS)  Nextgeneration method to derive the basic reproduction number of infectious disease models  In response to the recent, increasing interest in epidemiology, I will talk about the mathematical framework to derive the basic reproductive number for compartmental disease models: the NextGeneration Theorem (NGT). In general, whether diseases spread or not is determined by the leading eigenvalue (spectral radius) of a diseasefree steady state(s). For an SImodel, for instance, the conventional wisdom is that the instability of (S, I) =(S_0, 0) around the ODE for the model is determined by the real part of the eigenvalue. As the number of infectedclass compartments grows, however, it becomes increasingly difficult to determine the spectral radius of the associated matrix. NGT partially resolves this issue by (i) reducing the size of the matrix or dimension, (ii) making the matrix relatively sparse, and (iii) clarifying the biological meaning. I will talk about this theorem per se, though do not give its proof, with some illustrative applications (one of which is actually unsolved and therefore a quiz for you all!) as well as why graphtheory and stochastic analyses may be of great use in the discipline of epidemiology. The purpose of this talk is to facilitate future interactions between biologists including me and theoreticians who are interested in graph theory, matrix calculus, and/or dynamical systems. 
2020/5/15  Jeffery Fawcett (iTHEMS)  Basics of evolution and the evolution of SarsCoV2 

2020/5/22 



2020/5/29  ChinKai Chiu (iTHEMS)  Knot theory and topological semimetals  Topological nodal line semimetals host stable chained, linked, or knotted line degeneracies in momentum space protected by symmetries. We use the Jones polynomial as a general topological invariant to capture the global knot topology of the oriented nodal lines. We show that every possible change in Jones polynomial is attributed to the local evolutions around every point where two nodal lines touch. As an application of our theory, we show that nodal chain semimetals with four touching points can evolve to a Hopf link. We extend our theory to 3D nonHermitian multiband exceptional line semimetals and provide a recipe to understand the transition of the knot topology for protected nodal lines. 
2020/6/5  Tomoya Naito (U Tokyo/QHP)  Does Neutron Finite Size Affect Nuclear Structure?  Atomic nuclei consist of protons and neutrons, which interact via Coulomb and nuclear interactions. Since protons and neutrons have finite charge radii instead of point particles, these finitesize effects for the Coulomb interaction should be considered in the theoretical calculations. Nevertheless, since the contribution of the Coulomb interaction to the nuclear properties is weaker than that of the nuclear force, it was not considered properly. Recently, we have taken the finitesize effect to the Coulomb interaction into account for the calculation of nuclear structures. We found that the finitesize effects give a nonnegligible contribution to the nuclear binding energy [1].
[1] T. Naito, X. RocaMaza, G. Colò, and H. Liang. Phys. Rev. C Accepted (arXiv:2003.03177). 
2020/6/12 



2020/6/19  Akinori Tanaka (iTHEMS/AIP, Keio)  Markdown  the next generation markup language  Markdown is a lightweight markup language. Important features are easy to use, beautiful document output, and TeX rendering support. Thanks to these fascinating features, Markdown has been already one of common markup languages at least in engineering perspectives. But, I guess, there will be benefits even in scientific research perspectives. So, I would like to introduce how to use it and its applications. 
2020/6/26  Naomi Tsuji (iTHEMS)  Observational study of suprenova remnants  Supernova remnants, leftovers of supernova explosion, are believed to be factories of heavy elements and highenergy particles (cosmic rays). These ideas can be probed by observations of electromagnetic waves from supernova remnants. I will give a review talk of the observational studies; what we can learn from observations. 
2020/7/3  Masaki Taniguchi (iTHEMS)  Morse theory and Floer theory  In a study of topology, Morse theory provides a way to decompose a manifold into elementary parts. We first review a fundamental method in Morse theory. In Floer theory, we consider infinitedimensional versions of Morse theory for nice functionals. We explain an idea of Floer theory. 
2020/7/10  Catherine Beauchemin (iTHEMS)  What should we do about COVID19?  We have been analyzing and modelling the data for COVID19 cases in Tokyo and Saitama. We have built mathematical models to analyze the data and make predictions about where the case counts can be expected to go next, and what the consequences could be. For a while, things were going better and better, and daily cases were going down. With the increasing case count in Tokyo, Saitama, Osaka, etc., we now have some concerns. We would like an opportunity to show you some of our results and observations and hear your thoughts. How do you feel about the recent increases? If you were in charge, what decision would you take? As scientists, do we have a responsibility to make sure this information is provided to the general public so they have a clear understanding of the situation? We hope you will join us and share your thoughts. 
2020/7/17  Toshihiro Ota (iTHEMS)  Knots in Quantum Field Theory  In our three dimensional space knots (or links) are ubiquitous, not only in physics or mathematics, but also in biology, chemistry etc. (Rather, knots might be more common in biology and chemistry...) When knots appear in our world, they often look too complicated to be classified or distinguished. In this talk I will briefly explain a way to deal with the classification of knots using the general ideas of quantum field theory. 
2020/7/31  Yukimi Goto (iTHEMS)  On the ionization problem  From experiments, it seems that a neutral atom can only bind one or two extra electrons. This is a long standing open problem, sometimes referred to as the ionization conjecture. In this talk, I will briefly present the status of the conjecture. 
2020/8/7  Keisuke Taga (Waseda Universtiy)  Peeling tape as a reactiondiffusion system  When you peel a tape with appropriate velocity, you will find a sierpinskigascket like fractal pattern on the peeled trace. It is known that this pattern is caused by a switching of a peeling front structure. In this talk, I will introduce a new model of reactiondiffusion system, which can describe this pattern formation. 