Volume 83

iTHEMS Weekly News Letter

Hot Topic

iTHEMS end-of-the-year party, farewell party, and birthday party !

2019-12-19

iTHEMS end-of-the-year party + farewell party for Nagisa Hiroshima + birthday party for members who was born in December was held from 15:30- on Dec.13, 2019.
Before the start of the party, Nagisa who is leaving iTHEMS to become an assistant prof. at Toyama Univ. gave a 15 min. talk on the current status of Dark Matter (DM) Search and also on the activities of the iTHEMS DM Working Group. Her final conclusion was that DM would be a key scientific problem related to all iTHEMS Research Cells, i.e. Extreme Universe, Life & Evolution, Future Geometry, and Mathematics & AI. The room was full of researchers who are interested not only in dark matter but also in beautiful cakes, fruits, foods and in interesting conversations. Many thanks for iTHEMS secretaries who prepared for the wonderful party and thanks also to the people who brought sweets from all over the world!

Research News

Blasts from the past, article on RIKEN Research with reference of iTHEMS Researchers thumbnail

Blasts from the past, article on RIKEN Research with reference of iTHEMS Researchers

2019-12-18

The evolution of an exploding star begins more haphazardly than previously thought.

Reference

  1. Ferrand, G., Warren, D. C., Ono, M., Nagataki, S., Röpke, F. K. & Seitenzahl, I. R. From supernova to supernova remnant: The three-dimensional imprint of a thermonuclear explosion. , The Astrophysical Journal 877, 136 (2019)

Seminar Report

Math seminar talk by Dr. Wahei Hara

2019-12-18

The iTHEMS Math seminar was held on 4 December, inviting Wahei Hara from Waseda university. The title of the talk was “Noncommutative crepant resolutions and some higher dimensional flops”. The central topic was singularities of algebraic varieties and representation theory.
In the first part, the speaker explained the McKay correspondence as an example of connections between du Val singularities and representation theory of finite subgroups of the special linear group of degree two over the complex number field.
In the second part, the speaker talked about noncommutative crepant resolutions of singularities. There are several ways to interpret the Mckay correspondence. The derived McKay correspondence is the interpretation of the McKay correspondence in terms of derived categories. The notion of noncommutative crepant resolutions is the generalization of the derived McKay correspondence to a large class of singularities. We discussed applications of noncommutative resolutions to the study of derived categories in birational geometry.

Hot Topic

Report of Young Researcher Association for Biological Rhythms 2019

2019-12-19

Young Researcher Association for Biological Rhythms 2019, supported by RIKEN iTHEMS, was held at Kyushu University on December 7-8. In biology, there are many rhythmic phenomena, such as, circadian clocks, cell cycles, metabolic oscillations and so on. This research workshop has been a good opportunity for young researchers to get together and discuss wide field of biological rhythms. There were 6 invited lectures. The invited lectures contained various topics on biological rhythms: insulin oscillations, circadian clocks of insects, chronopharmacology, methylation cycles, mathematical biology, and cyanobacterial circadian clocks. Because these research topics attracted many participants, we enjoyed active discussions until late at night.

Upcoming Events

Seminar

ABBL-iTHEMS Joint Astro Seminar

Constraining superheavy dark matter with the multi-messenger observations of accompanying radiation

December 20 (Fri) at 14:00 - 15:00, 2019

Yana Zhezher (Institute for Cosmic Ray Research (ICRR), The University of Tokyo)

One of the main alternatives for the weakly interacting massive particles (WIMP) dark matter scenario are the super-heavy X particles with masses larger than the weak scale by orders of magnitude. We assume the experimentally more plausible scenario of decaying superheavy dark matter (SHDM), which leads to the production secondary particles: electrons, positrons, gamma rays and neutrinos. The hypothetical X-particle has two main parameters: it’s mass MX and lifetime 𝜏, which can be indirectly constrained by comparisons of predicted flux of secondary particles with the astrophysical observations. We present the limits on the SHDM parameters derived with the multi-messenger data from the Fermi-LAT, IceCube and other experiments.

Venue: Seminar Room #132, 1F Main Research Building, RIKEN

Event Official Language: English

Conference

2019 RIKEN Symposium: Understand to Predict the properties of Things and Matters through Computational Calculations ~ Data Science, Natural Intelligence and Category Theory~

December 23 (Mon) at 9:50 - 18:10, 2019

This workshop is supported by RIKEN iTHEMS (RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program).

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

Event Official Language: Japanese

Workshop

RIKEN-Kyushu workshop on particle, nuclear and astrophysics thumbnail

RIKEN-Kyushu workshop on particle, nuclear and astrophysics

December 23 (Mon) - 24 (Tue), 2019

Organizers
Emiko Hiyama (Kyushu U./RIKEN)
Hiroshi Suzuki (Kyushu U.)
Tetsuo Hatsuda (RIKEN)

Venue: Faculty of Science, Ito Campus, Kyushu University

Event Official Language: Japanese

Seminar

The 32nd QCD Club

December 26 (Thu) at 15:00 - 17:00, 2019

Event Official Language: Japanese

Seminar

Tipping point detection of nonlinear dynamics by dynamic network biomarkers, and short-term time-series data prediction by randomly distributed embedding

January 15 (Wed) at 14:00 - 16:30, 2020

Luonan Chen (Professor, Excutive director, Chinese Academy of Sciences, China)

He will talk about theoretical study on complex network data, including clinical data.

His talk consists of two parts:
14:00-15:00: Detecting the tipping points of dynamic processes by dynamic network biomarkers
15:00-15:30: Coffee break
15:30-16:30: Predicting future dynamics of short-term time-series data by randomly distributed embedding

First part of his talk is for general audience.
In second part of his talk, he will explain mathematical basis of his study in detail.

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

Event Official Language: English

Colloquium

iTHEMS Colloquium

Exploring the learning principle in the brain

January 16 (Thu) at 15:30 - 17:00, 2020

Taro Toyoizumi (Team Leader, RIKEN Center for Brain Science (CBS))

Animals adapt to the environment for survival. Synaptic plasticity is considered a major mechanism underlying this process. However, the best-known form of synaptic plasticity, i.e., Hebbian plasticity that depends on pre- and post-synaptic activity, can surge coincident activity in model neurons beyond a physiological range. Our lab has explored how neural circuits learn about the environment by synaptic plasticity. The instability of Hebbian plasticity could be mitigated by a global factor that modulates its outcome. For example, TNF-alpha that mediates homeostatic synaptic scaling is released by glia, reflecting the activity level of surrounding neurons. I show that a specific interaction of Hebbian plasticity with this global factor accounts for the time course of adaptation to the altered environment (Toyoizumi et al. 2015). At a more theoretical level, I ask what is the optimal synaptic plasticity rule for achieving an efficient representation of the environment. A solution is the error-gated Hebbian rule, whose update is proportional to the product of Hebbian change and a specific global factor. I show that this rule, suitable also in neuromorphic devices, robustly extracts hidden independent sources in the environment (Isomura and Toyoizumi 2016, 2018, 2019). Finally, I introduce that synapses change by intrinsic spine dynamics, even in the absence of synaptic plasticity. I show that physiological spine-volume distribution and stable cell assemblies are both achieved when intrinsic spine dynamics are augmented in a model (Humble et al.2019).

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

Broadcast: R311, 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

Upcoming Visitors

December 20 (Fri), 2019

Pei-Ming Ho

Distinguished Professor, Department of Physics, National Taiwan University, Taiwan

Visiting Place: #245, 2F, Main Research Building

Catherine Beauchemin thumbnail

December 23 (Mon), 2019 - January 6 (Mon), 2020

Catherine Beauchemin

Senior Visiting Scientist, iTHEMS / Professor, Department of Physics, Ryerson University, Canada

Research fields: Virophysics

Visiting Place: #231, 2F, Main Research Building

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