Theory of Operator Algebras (6th)

December 20 (Thu) at 15:30 - 17:00, 2018

Yosuke Kubota (Research Scientist, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS))

Title: An introduction to operator algebras Abstract: Operators are linear maps from a (usually an infinite dimensional) linear space (most frequently the Hilbert space) to itself, which is like matrices of infinite degree. Operators form an algebra by obvious addition and multiplication. Operators appear in most of the fields in mathematics, in algebra, in geometry, in analysis, ... Some of the key words at the beginning of these lectures are "spectral theory" "operator algebras" "Tomita-Takesaki theory". These lectures are for non-professional people.

Venue: Seminar Room #160

Event Official Language: Japanese

Biology Seminar

December 13 (Thu) at 14:00 - 16:00, 2018

Yusuke Kazama (Team Leader, Plant Genome Evolution Research Team, RIKEN Nishina Center for Accelerator-Based Science (RNC))
Jeffrey Fawcett (Senior Research Scientist, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS))

Speaker: Jeffrey Fawcett (iTHEMS) Title: Introduction to Genomics Abstract: The genetic information, or the genome, of almost all species are determined by the order (i.e. the "sequence") of millions of nucleotides represented by A, G, C, and T. I will first outline what we already know about the genome, how they differ across species and individuals, and how we can study them. I will then briefly introduce "3D Genomics", a topic that is becoming quite hot in biology now: the genome is not only a one dimensional "sequence" information but the chromosomes must be folded up to fit into the cell nuclei, and this 3D structure of the chromosome and the spatial positioning of the genes might be important for the biology of each species. Speaker: Yusuke Kazama (Nishina Center) Title: 大きな玉ほど大きく壊す：シロイヌナズナを用いて明らかにした重イオンビーム変異の特徴 Abstract: 重イオンビームはγ線やX線よりも線エネルギー付与（LET)が高いことで知られ、核種やビームの速度を選択することによりLETを調節して照射することもできる。私たちは、モデル植物シロイヌナズナを用いてLETが変異誘発に与える影響を調べ、変異率が最大となるLET＝30.0 keV/μm(LETmax)を発見した。突然変異体の全ゲノム解析を行ない、LETmaxでは塩基置換や小さい欠失が多いのに対し、LET=290 keV/μmでは大きな欠失や染色体再編成の頻度が高いことを明らかにした。目的や材料に合わせて「高効率で1遺伝子を破壊するにはLETmax照射」を、「2遺伝子以上の破壊や染色体再編成の誘発には高LET照射」を行うオンデマンド照射技術を確立した。今後は、染色体再編成が植物の形質に与える影響を、3Dゲノム構造の変化、クロマチン構造の変化、遺伝子発現の変化に注目して研究していきたい。

Venue: Seminar Room #160

Event Official Language: English

The physical and biological basis of tissue growth

December 12 (Wed) at 15:00 - 16:30, 2018

Kaoru Sugimura (Program-Specific Research Center Associate Professor, Kyoto University)
Shuji Ishihara (Project Associate Professor, The University of Tokyo)

15:00 - 15:40 "Physical and molecular mechanism of cell rearrangement" Kaoru Sugimura 15:50 - 16:30 "From cells to tissue: A continuum model of epithelial tissue mechanics" Shuji Ishihara

Venue: Okochi Hall

Broadcast:R511, Computational Science Research Building / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

Event Official Language: Japanese

Cosmic-ray air showers: new arrays for searching origins and link to the collider physics

December 7 (Fri) at 14:00 - 15:00, 2018

Takashi Sako (Institute for Cosmic Ray Research (ICRR), The University of Tokyo)

Venue: Seminar Room #160

Event Official Language: English

Probability density functions attached to zeta functions

December 6 (Thu) at 16:00 - 17:00, 2018

Masahiro Mine (Tokyo Institute of Technology)

The study of the value-distribution of the Riemann zeta function is a classical topic in analytic number theory. In 1930s, Bohr and Jessen proved the existence of a certain limit value regarded as the probability that values of the Riemann zeta function belong to a given region in the complex plane. After Bohr and Jessen, similar results were proved for many other zeta functions. In this talk, I'll talk about density functions of such probabilities attached to the value-distributions of zeta functions. The density functions, which were named M-functions'' by Ihara, are connected with mean values of zeta functions, distributions of zeros of zeta functions, and so on.

Venue: Seminar Room #160

Event Official Language: English

Workshop on Recent Developments of Chiral Matter and Topology

December 6 (Thu) - 9 (Sun), 2018

The aim of this workshop is to gather researchers of high-energy and condensed-matter physics working on chiral Matter and Topology, to exchange ideas and establish collaborations to tackle unsolved issues and carry out future extensions. The workshop expects to welcome 40-60 participants who are interested in the aforementioned topics. Organizers: Tomoki Ozawa, Tetsuo Hatsuda (RIKEN iTHEMS) Di-Lun Yang (RIKEN Nishina Center; YITP, Kyoto) Chang-Tse Hsieh (Kavli IPMU / ISSP, the Univ. of Tokyo) Jiunn-Wei Chen, Guang-Yu Guo (National Taiwan Univ.) Hsiang-Nan Li (Academia Sinica)

Venue: National Taiwan University, Taipei, Taiwan

Event Official Language: English

On A_2-liftings of sum formulas and Bowman-Bradley type formulas for finite multiple zeta values

November 22 (Thu) at 11:40 - 12:40, 2018

Shin-ichiro Seki (Tohoku University)

Both the sum formula and Bowman-Bradley's theorem for multiple zeta values are well known. Recently, Saito and Wakabayashi proved counterparts of these two formulas for A-finite multiple zeta values. In this talk, I will explain that A_2-liftings of some parts of Saito-Wakabayashi's results have simple forms using Seki-Bernoulli numbers. The first part of this talk is a joint work with Shuji Yamamoto. The second part is a joint work with Hideki Murahara and Tomokazu Onozuka.

Venue: Seminar Room #160

Event Official Language: English

Generating functions of CM & RM values

November 22 (Thu) at 10:30 - 11:30, 2018

Toshiki Matsusaka (Kyushu University)

The special values of the elliptic modular j function j(z) at imaginary quadratic points are known as singular moduli (CM values), and play important roles in algebraic number theory. As a real quadratic analogue, Kaneko (2009) defined the `values’ of j(z) at real quadratic points (RM values). In 2011, Duke-Imamoglu-Toth showed that the generating function of the traces of these CM & RM values becomes a harmonic Maass form of weight 1/2. In this talk, I shall introduce a new class called polyharmonic weak Maass forms, inspired by works of Lagarias-Rhoades on the Kronecker limit formula, and give a generalization of Duke-Imamoglu-Toth’s work for any polyharmonic weak Maass form.

Venue: Seminar Room #160

Event Official Language: English

iTHEMS-Kyushu WS - from particles and nuclei to cosmos -

November 21 (Wed) - 22 (Thu), 2018

Program: Nov.21 (Wed) 13:00-13:05: T. Hatsuda (RIKEN) Introduction 13:05-13:50: T. Doi (RIKEN) Lattice QCD and Baryon Interactions 13:50-14:20: T. Hirakida (Kyushu) Persistent homology and confinement-deconfinement transition 14:20-14:50: H. Takaura（Kyushu）Strong coupling constant from inter-quark potential - OPE calculation without renormalon ambiguity - 14:50-15:20: Y. Yamaguchi (RIKEN)　Short range pi J/psi-DDbar* potential 15:20-15:35: Coffee Break 15:35-16:20: Y. Hidaka (RIKEN) Nambu-Goldstone theorem and spontaneous symmetry breaking 16:20-16:50: T.M. Doi(RIKEN) PMS condition of optimized perturbation theory and anti-Stokes line 16:50-17:20: O. Morikawa（Kyushu）Numerical study of the N=2 Landau-Ginzburg model 17:20-17:50: M. Hongo (RIKEN)　Effective field theory for dissipative systems 18:00-20:00: Banquet Nov.22 (Thur) 9:30-10:15: H. Togashi (RIKEN)　Equation of state for dense matter and astrophysical phenomena at high baryon density 10:15-10:45: S. Ogawa (Kyushu) Microscopic optical potentials with projectile breakup 10:45-11:00: Coffee Break 11:00-11:30: S. Furusawa (RIKEN) Supernovae and neutrinos 11:30-12:00: K. Takami (KCCT) Simulations of neutron-star mergers Co-hosted by　 Graduate School of Science, Kyushu Univ. RIKEN iTHEMS Organized by Emiko Hiyama (Kyushu Univ. /RIKEN) Hiroshi Suzuki (Kyushu Univ.) Tetsuo Hatsuda (RIKEN iTHEMS)

Venue: Integrated Innovation Building (IIB)

Event Official Language: Japanese

Study of density dependent nuclear symmetry energy by using heavy RI collisions at RIKEN-RIBF

November 16 (Fri) at 14:00 - 16:00, 2018

Tada-aki Isobe (Senior Research Scientist, Radioactive Isotope Physics Laboratory, RIKEN Nishina Center for Accelerator-Based Science (RNC))

The nuclear Equation of State (EoS) is a fundamental property of nuclear matter. An international collaboration, named SPiRIT, to study the density dependence of asymmetry term in nuclear EoS has been formed since 2009. The main aim of this collaboration is to make the constraint on the asymmetry term of nuclear EoS for higher dense region($\rho>\rho_0$). In this talk, the conceptual idea of the project will be given in addition to some result of data analysis for the physics run performed at 2016 spring.

Venue: Seminar Room #160

Event Official Language: English

Spintronics in Non-Inertial Frames

November 15 (Thu) at 13:00 - 18:00, 2018

Mamoru Matsuo (University of Chinese Academy of Sciences, China)

Venue: Seminar Room #160

Event Official Language: Japanese

New Venues in Formation and Detection of Primordial Black Hole Dark Matter

November 12 (Mon) at 14:00 - 15:00, 2018

Volodymyr Takhistov

Abstract: Primordial black holes (PBH) provide an attractive non-particle dark matter (DM) candidate. I will discuss a novel PBH production mechanism that can appear generically in models with scalar fields. Recent re-evaluations of PBH constraints suggest that the open parameter space for PBHs to constitute all of dark matter is appreciably larger than previously thought. I will show how compact stars can serve as laboratories for probing it. The variety of resulting novel astrophysical signals are of particular interest to the vibrant field of multi-messenger astronomy. More-so, PBH-star interactions suggest an elegant resolution to some of the most puzzling questions in astrophysics, such as the origin of gold and other heavy elements.

Venue: Seminar Room #160

Event Official Language: English

Nerd Nite Tokyo

November 9 (Fri) at 20:00 - 22:00, 2018

Ade Irma Suriajaya (Special Postdoctoral Researcher, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS))

Chacha will tell us about infinities, some bad math, and some good math. Price: ¥1000, but speakers get in free Food and drinks available at the event

Venue: Nagatacho GRID (2-5-3 Hirakawa-cho, Chiyoda-ku, Tokyo 102-0093)

Event Official Language: English

The 28th QCD Club

November 9 (Fri) at 15:00 - 17:00, 2018

Title: Application of a gradient flow method to thermodynamics of QCD with dynamical quarks Language: Japanese or English

Event Official Language: English

The 6th MACS Colloquium

November 8 (Thu) at 15:00 - 17:30, 2018

Chikara Furusawa (Team Leader, Laboratory for Multiscale Biosystem Dynamics, RIKEN Center for Biosystems Dynamics Research (BDR) / Professor, The University of Tokyo)
Ken Takai (Program Director, Extremobiosphere Research Program, Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC))

15:00- Teatime 15:15- Talk by Prof. Chikara Furusawa 16:30- Talk by Dr. Ken Takai The 6th MACS colloquium supported by iTHEMS. It will be broadcasted to Wako, but if you can join the colloquium physically in Kyoto, that would be better. iTHEMS provides good cakes/cookies at Kyoto!

Venue: Lecture room #401, Graduate School of Science Building No 6, Kyoto University

Event Official Language: Japanese

Theory of Operator Algebras (5th)

November 8 (Thu) at 13:30 - 15:00, 2018

Yosuke Kubota (Research Scientist, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS))

Venue: Seminar Room #160

Event Official Language: Japanese

Spintronics: from electrons to quarks (iTHEMS-CEMS Joint Meeting)

November 7 (Wed) at 10:00 - 17:30, 2018

Program: 10:00-10:15　T. Hatsuda (RIKEN) “Opening” 10:15-10:45　S. Maekawa (RIKEN) “Introduction to Spintronics”. 10:45-11:45　M. Matsuo (KITS, Beijing) “Spintronics phenomena in non-inertial frames” (Review) 13:30-14:30　M. Hongo (Riken) “Introduction to chiral transport phenomena” (Review) 14:30-15:00　Y. Hidaka (RIKEN) “Non-Equilibrium Quantum Transport of Chiral Fluids” 15:30-16:00　Y. Tsutsumi (RIKEN) “Spin-Vorticity Coupling in Liquid He”. 16:00-16:30　T. Takiwaki (NAOJ) “Chiral magnetohydrodynamic turbulence in core-collapse supernovae” 16:30-17:30　Discussion (and Closing by T. Hatsuda)

Venue: Seminar Room #160

Event Official Language: Japanese

Population genetics of duplicated genes

November 1 (Thu) at 15:30 - 18:00, 2018

Hideki Innan (The Graduate University for Advanced Studies (SOKENDAI))

Venue: Seminar Room #160

Event Official Language: English

Assembly rules and a theory for invasion and extinction in minimal food webs

October 29 (Mon) at 15:00 - 18:00, 2018

Namiko Mitarai (Associate Professor, Niels Bohr Institute, University of Copenhagen, Denmark)

We propose a theory of the evolution of a minimal food web by sequential invasion of new species [1]. Our theory is based on the standard generalized Lotka-Volterra equations, where basal species compete through resource depletion [2]. The considered food webs are “minimal”, as each species only feeds on a single resource, leading to a hierarchical, tree-like food web [1,3]. We prove that at each invasion step there is one uniquely determined outcome: either the invader peacefully coexists with the residents and resources are re-distributed; the invader is eliminated; or one or several of the resident species are removed in a uniquely defined extinction cascade. At the end of either of these processes the resulting food web relaxes to a globally stable (and feasible) steady state. We break down the essence of our theory in the conceptual “invasion extinction model” (IEM), which allows us to analytically compute the persistence time and the extinction size distribution.

Venue: Seminar Room #160

Event Official Language: English

Relations between fractal dimensions and arithmetic progressions

October 23 (Tue) at 11:35 - 12:35, 2018

Kota Saito (Nagoya University)

In this talk we give estimates for the dimensions of sets in real numbers which uniformly avoid finite arithmetic progressions. More precisely, we say that $F$ uniformly avoids arithmetic progressions of length $k\geq 3$ if there is an $\epsilon>0$ such that one cannot find an arithmetic progression of length $k$ and gap length $\Delta>0$ inside the $\epsilon\Delta$ neighbourhood of $F$. Our main result is an explicit upper bound for the Assouad (and thus Hausdorff) dimension of such sets in terms of $k$ and $\epsilon$. In the other direction, we give examples of sets which uniformly avoid arithmetic progressions of a given length. We also consider higher dimensional analogues of these problems, where arithmetic progressions are replaced with arithmetic patches lying in a hyperplane. As a consequence, we obtain a discretised version of a `reverse Kakeya problem': we show that if the dimension of a set in $\mathbb{R}^d$ is sufficiently large, then it closely approximates arithmetic progressions in every direction. The above is a joint work with Fraser and Yu. Finally we show that the converse of `reverse Kakeya problem' does not hold. This is a single-author work.

Venue: Large Meeting Room, 2F Welfare and Conference Building (Cafeteria)

Event Official Language: English