Thursday, June 3, 10:00- iTHEMS Biology Seminar
Friday, June 4, 11:30- Coffee Meeting

A collaborative research group, including Prof. Hideaki Aoyama (Senior Visiting Scientist, iTHEMS), has successfully used the latest big data network science to understand the structure of money flows between corporate accounts at regional banks.

See related link for details.

On May 27 (JST), we had online talk by Dr. Kouki Uchinomiya at iTHEMS Biology Seminar. He was one of active members of RIKEN iTHES, and currently he is at Central Research Institute of Electric Power Industry in Tokyo. This time, Kouki talked about radiation and cancer risk.
Radiation can cause DNA damage for which it can cause cancer in our body. In the field of radiation and cancer, there has been a mystery that cancer risk decreases as the dose rate of radiation (Gy/h) decreases while the total dose of radiation fixed. By incorporating the competition between the normal and the damaged cells by radiation into a simple mathematical model, he successfully explained the mysterious phenomena. His model revealed that the key parameters including a relative reproductive ability of the damaged cells determine the cancer risk. According to him, those parameters will be experimentally measured in the near future, and we understand that the model should contribute to the quantitative estimation of cancer risk by radiation.
During and after the talk, there were stimulating discussions as for the philosophy behind his very simple model and a possible extension to the model with the effect of immune system. We enjoyed his concise talk very much. Thanks Kouki!

Reported by Gen Kurosawa

On May 24, there was an iTHEMS math seminar by Dr. Michiya Mori.

In the first part, he explained his research on Lowebner theorems. He first described the notion of abstract order. He then introduced an order on the space of the hermitian matrix. He explained Molnar's results that the order-preserving map must be affine on a particular good subset of matrices. Lastly, he explained his results with his collaborator that a map on matrix domain is an order isomorphism if and only if it has a good extension to the upper half-space.

In the second part, the speaker introduced the projective Hilbert space, the space of all quantum states, and Fubini-Study metric, an "argument" on the projective Hilbert space. He then introduced the result by Wigner that any bijective maps preserving Fubini-Study metric are unitary or anti-unitary. The speaker introduced Uhlhorn's variant of this result: if the dimension of the space is larger than three, any bijection preserving argument π/2 is unitary or anti-unitary. The speaker also explained that Gehér extended Uhlhorn's works for other cases, but there was one open case. The speaker explained his result with Gehér that the variant of the result by Uhlhorn holds for this last case.

Reported by Keita Mikami

On May 19, Dr. Kyosuke Adachi talked about “Amino acid sequence and protein phase separation” at the journal club of information theory study group.

First, he introduced the history of protein states, from its structure observed with X-ray to intrinsically disordered region (IDR) and liquid-liquid phase separation. In this talk, the speaker focused on IDR and phase separations.
Second, he explained some biological functions of phase separation, such as compartmentalization of specific molecules, facilitation of biochemical reaction, and stress response. And the talk moved a question of what kind of sequence feature determines phase properties.
Mainly, the speaker discussed coarse-grained models, which are expected to determine phase properties.
Finally, he mentioned the problem of how to classifying IDRs and the importance of the coarse-grained sequence.

Thank you, Adachi-san, for the interesting talk!

Reported by Yukimi Goto

I'm Akira Harada, a RIKEN SPDR since April 2021. I'm interested in astrophysics, especially supernovae. The core-collapse supernova (CCSN) is the explosive death of a massive star. Because of the extreme environment realized at the center of the CCSN, the explosion mechanism involves a vast field of physics, namely hydrodynamics, nuclear physics, neutrino physics, and gravitational physics. Besides, understanding such a complicated phenomenon requires numerical simulations. I'm trying to reveal the mechanism by exploiting all these pieces of knowledge. I'd like to get stimulated from interdisciplinary conversations with iTHEMS people.