# Upcoming Events

## Math Lecture

### Introduction to Public-Key Cryptography (8th)

February 7 at 13:30 - 15:00, 2019

Dr. Eren Mehmet Kıral (Visiting Scientist, iTHEMS)

Venue: Seminar Room #160, 1F Main Research Building, RIKEN

Event Official Language: English

## Colloquium

### The 7th MACS colloquium

February 7 at 15:00 - 17:30, 2019

Dr. Akira Tsuchiyama (Professor, Division of Earth and Planetary Sciences, Graduate School of Science/Faculty of Science, Kyoto University)

15:00 ティータイム

15:15 2018年度MACS成果報告会

16:40 『～鉱物に耳をあてがう、地球と宇宙が聞こえる〜「はやぶさ」サンプルから聞こえてきたこと、「はやぶさ２」サンプルへの期待』土`山 明氏

The 7th MACS colloquium is 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 confectionary at Kyoto!

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

Event Official Language: Japanese

## Colloquium

### Tropical Rain Forest

February 21 at 15:30 - 17:00, 2019

Prof. Akiko Satake (Professor, Department of Biology, Faculty of Science, Kyushu University)

Venue: Okochi Hall, 1F Laser Science Laboratory, RIKEN

Broadcast: #311, Computational Science Research Building, R-CCS, Kobe Campus, RIKEN / SUURI-COOL (Kyoto), #204-205, 2F Maskawa Building for Education and Research, North Campus, Kyoto University / SUURI-COOL (Sendai), #303, 3F AIMR Main Building, Advanced Institute for Materials Research (AIMR), Tohoku University

Event Official Language: English

## Math Lecture

### Theory of Operator Algebras (8th)

March 5 at 14:00 - 15:00, 2019

Dr. Yosuke Kubota (Research Scientist, 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, 1F Main Research Building, RIKEN

Event Official Language: Japanese

## Math Lecture

### Theory of Operator Algebras (9th)

March 5 at 15:30 - 16:30, 2019

Dr. Yosuke Kubota (Research Scientist, 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, 1F Main Research Building, RIKEN

Event Official Language: Japanese

## Workshop

### Workshop of Nuclear-Astrophysics by UKAKUREN/Japan Forum of Nuclear Astrophysics (JaFNA): Nuclear data & Heavy Element Nucleosynthesis

March 6 - 8, 2019

We are pleased to announce that we will have a meeting on Nuclear-Astrophysics at Hokkaido Univ. Especially this time we will focus on the impact of nuclear data & nucleosynthesis of heavy elements. Gravitational wave is another keyword.

This workshop is held by UKAKUREN (JaFNA), together with Nuclear Reaction Data Centre, Hokkaido University (JCPRG). This workshop is supported by iTHEMS, CNS, RCNP, NAOJ, KEK, and WNSC.

You are welcomed to join us. For registration, please fill in the attached form (in Japanese) and send it to: sec-ukakuren18@kek.jp by 30th November 2018.

We are looking forward to seeing you at Hokkaido U.

Organizers

T. Kajino (Chair), T. Kawabata (Osaka), H. Utsunomiya (Konan), S. Nishimura (RIKEN), H. Yamaguchi (CNS), T.Hayakawa (QST), T.Motobayashi (RIKEN),

K.Terada(Osaka), S.Nagataki(RIKEN), S.Chiba(TIT), T.Tamagawa(RIKEN), W.Aoki(NAOJ), S.Wanajo(AEI), S.Kubono(RIKEN), T.Shima(RCNP)

Venue: Hokkaido University Conference Hall

Event Official Language: Japanese

## Colloquium

### ZetaValue2019-iTHEMS Special Mathematics Colloquium

March 21 at 14:00 - 17:30, 2019

Prof. Kohji Matsumoto (Nagoya University)

Prof. Jörn Steuding (University of Würzburg, Germany)

Venue: Okochi Hall, 1F Laser Science Laboratory, RIKEN

Event Official Language: English

## Workshop

### Value distribution of zeta and L-functions and related topics

March 22 - 27, 2019

March 22–26, 2019

Main Conference (invited talks, posters and a limited number of short contributed talks)

Welcome Reception: March 22, 2019 (18:00~20:00)

Conference Dinner: March 25, 2019 (18:30~21:00)

March 27, 2019 (9:30~17:00)

One-day Workshop (a series of short contributed talks by young researchers to facilitate active discussions)

ORGANIZING COMMITTEE

Ade Irma Suriajaya (RIKEN)

Yoshinosuke Hirakawa (Keio University)

Masataka Ono (Kyushu University)

Shin-ichiro Seki (Tohoku University)

Keiju Sono (Ehime University)

Shingo Sugiyama (Nihon University)

Yuta Suzuki (Nagoya University)

ADVISORY COMMITTEE

Tetsuo Hatsuda (RIKEN iTHEMS)

Kenichi Bannai (Keio University, RIKEN AIP Center)

Venue: Okochi Hall, 1F Laser Science Laboratory, RIKEN / Large Meeting Room, 2F Welfare and Conference Building (Cafeteria), RIKEN

Event Official Language: English

## School

### g-RIPS Sendai 2019

June 17 - August 9, 2019

GRIPS (Graduate-level Research in Industrial Projects for Students)-Sendai program was held last summer (June 18 - Aug. 10, 2018) with the support of iTHEMS as well as other institutions and companies. Two industrial projects were launched under the suggestion of TOYOTA and NEC, and two teams composed of US and Japanese students have worked intensively to find solutions of these problems. See for the details of the GRIPS program and the summary of activities at GRIPS-Sendai 2018.

This year, GRIPS-Sendai program will be held from June 17 through Aug. 9, 2019 with a larger scale under the support of iTHEMS. Stay tuned for further information.

Event Official Language: English

# Paper of the Week

## Index theory and topological phases of aperiodic lattices

2019-01-22

The paper studies the interactions between dynamical systems, represented via groupoid operator algebras, and index theory, described using Kasparov's bivariant K-functor. The key motivating example is the dynamical systems associated to Delone sets.

Delone sets give a model of aperiodic atomic configurations, where the material may be amorphous or quasi-crystalline. The atomic configuration does not have a group structure, but key properties can be encoded in a discrete groupoid. We construct bivariant K-cycles, a generalisation of K-theory classes, that encode the dynamics of the aperiodic lattice. For the case of quasi-crystalline configurations, we obtain finer information coming from the long-range aperiodic order of the material.

We then use our constructed K-cycles to define bulk topological phases of aperiodic materials. A bulk-boundary correspondence is also shown, which arises from factorisation properties of the constructed K-cycles.

Reference:

Chris Bourne, Bram Mesland

"Index theory and topological phases of aperiodic lattices"

doi: 10.1007/s00023-019-00764-9

arXiv: 1807.03972

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