iTHEMS Weekly News Letter

Press Release

Dr. Shigehiro Nagataki thumbnail
Dr. Masaomi Ono thumbnail
Mr. Akira Dohi thumbnail

Press Release from Chandra, NuSTAR and INAF on 34th Happy Birthday of SN1987A

2021-02-24

The paper "Indication of a Pulsar Wind Nebula in the hard X-ray emission from SN 1987A" by Dr. Shigehiro Nagataki (Deputy Program Director, iTHEMS), Dr. Masaomi Ono (Research Scientist, iTHEMS) and Mr. Akira Dohi (Junior Research Associate, iTHEMS) was published in the NASA and INAF press releases on February 23, 2021 (SN1987A's 34th birthday!).

The following is a message from Dr. Nagataki;
"We detected high-energy X-rays by NuSTAR, which are likely to come from activities of pulsar wind nebula of SN1987A (it has been a big mystery why the neutron star in SN1987A has not been detected for 34 years since Prof. Koshiba et al. detected neutrinos at the birth of proto-neutron star in SN198A). Our paper will be published by Astrophysical Journal Letters this week."

Seminar Report

ABBL-iTHEMS Joint Seminar by Prof. Gordon Baym on February 22, 2021

2021-02-26

On Feb. 22, our iTHEMS colleague, Gordon Baym, gave an online talk from Urbana-Champaign on the detection of the primordial neutrinos created in the early Universe. We are in the sea of those neutrinos at the present day with the neutrino density of about 56/cc for each neutrino species. Although neutrinos (anti-neutrinos) are left-handed (right-handed) in early Universe, both cosmic and galactic magnetic fields as well as the gravitational inhomogeneities can flip their spins with respect to the momentum, so that the helicities (spin projection along the direction of the momentum) of the relic neutrinos could be a new probe of cosmic gravitational and magnetic fields. More that 60 participants attended this interesting seminar and there were lively discussions during and after the talk.

Seminar Report

Biology Seminar by Mr. Junichiro Iwasawa on February 18, 2021

2021-02-25

On 18th February, we invited Junichiro Iwasawa from the University of Tokyo, who gave a talk about the unique study to identify the evolutionary constraints of drug-resistance in Escherichia coli using automated high-throughput laboratory experiments. He first talked about the background of drug resistance evolution and about the well-known / novel resistance-conferring genes for E. coli that were elucidated from their data. He then moved on to the details of the data analyses and explained the combined method of random forest regression and principal component analysis on the multi-omics data. We enjoyed a long discussion on every single detail of the impressive work. We especially thank him for accepting our invitation despite the tight schedule with his dissertation. Thank you again for the great talk!
-Ryosuke Iritani

Seminar Report

Biology Seminar by Dr. Hiroshi Yokota on February 25, 2021

2021-02-25

In iTHEMS biology seminar on Feb. 25th, Dr. Hiroshi Yokota (iTHEMS) talked about the mechanism of the non-linear response of DNA under stretching force. In the introduction part, he mentioned the experimental technique using the magnetic tweezer to measure the extension of DNA under stretching force, and he also showed the experimental results of the non-linear response of DNA. He then explained the strategy to clarify the origin of non-linearity by applying mathematical modeling and statistical physics. Introducing the worm-like chain model, he transformed the Hamiltonian in an elegant way and analytically obtained the formula of the extension, which explains the experimental data. His description of the model was very clear, and there were many questions and discussions. We are thankful to Hiroshi for the intriguing talk.

Kyosuke Adachi

Seminar Report

Information Theory SG by Dr. Ryusuke Hamazaki on February 17, 2021

2021-02-19

On 17th February, we had Ryusuke Hamazaki (from RIKEN Hakubi and iTHEMS) talking about the recent studies on the large deviation principle in our journal club of the Information Theory Study Group.
He started off by demonstrating Bernoulli's process and how to compute the large deviations, and then defined the Level 2.5 large deviations in Markovian jump process, thereby providing the derivation of a recently proposed inequality (the thermodynamic uncertainty relation). Finally, he explained possible extensions to quantum systems. The talk received numerous questions in every single part, specifically from those interested in the derivation and application of the Level 2.5 large deviation. Thanks, Ryusuke, for the great and inspiring talk!
Ryosuke Iritani (iTHEMS)

Upcoming Events

Conference

Co-hosted by iTHEMS

The 8th Asia-Pacific Conference on Few-Body Problems in Physics (APFB2020)

March 1 - 5, 2021

The next Asia-Pacific conference on few-body problems in physics (APFB2020) will be held at KANAZAWA BUNKA HALL, Kanazawa, Japan, from 1 to 5 March 2021. RIKEN iTHEMS is a co-host of this conference together with RIKEN Nishina Center, Kyushu Univ., Osaka Univ. and Tohoku Univ.

The registration deadline for the online participation is Feb. 25, 2021.

Venue: KANAZAWA BUNKA HALL

Event Official Language: English

Seminar

Quantum Matter Seminar

Exceptional Topology of Non-Hermitian Systems: from Theoretical Foundations to Novel Quantum Sensors

March 3 at 17:00 - 18:15, 2021

Prof. Jan Budich (Professor, Quantum Many-Body Physics, TU Dresden, Germany)

CET: 9:00a.m. - 10:15a.m. on March 3, 2021
JST: 5:00p.m. - 6:15p.m. on March 3, 2021
EST: 3:00a.m. - 4:15a.m. on March 3, 2021

In a broad variety of physical scenarios ranging from classical meta-materials to open quantum systems, non-Hermitian (NH) Hamiltonians have proven to be a powerful and conceptually simple tool for effectively describing dissipation. Motivated by recent experimental discoveries, investigating the topological properties of such NH systems has become a major focus of current research. In this talk, I give an introduction to this rapidly growing field, and present our latest results. Specifically, we discuss the occurrence of novel gapless topological phases unique to NH systems. There, the role of spectral degeneracies familiar from Hermitian systems such as Weyl semimetals is played by exceptional points at which the effective NH Hamiltonian becomes non-diagonalizable. Furthermore, we show how guiding principles of topological matter such as the bulk boundary correspondence are qualitatively changed in the NH realm. Finally, we demonstrate that the sensitivity of NH systems to small changes in the boundary conditions may be harnessed to devise novel high-precision sensors.

Venue: via Zoom

Event Official Language: English

Seminar

iTHEMS Biology Seminar

Microeconomics of metabolism

March 10 at 10:00 - 11:00, 2021

Mr. Jumpei Yamagishi (Kaneko Laboratory, University of Tokyo)

Metabolic behaviors of proliferating cells are often explained as a rational choice to optimize cellular growth rate. In contrast, microeconomics formulates consumption behaviors as optimization problems of utilities. We pushed beyond this analogy to precisely map metabolism onto the theory of consumer choice.

We thereby revealed the correspondence between and a general mechanism for mysteries in biology and economics: the Warburg effect, a seemingly-wasteful but ubiquitous phenomenon where cells favor aerobic glycolysis over more energetically-efficient respiration, and Giffen behavior, the unexpected consumer behavior where a good is demanded more as its price rises. The correspondence implies that respiration is counterintuitively stimulated when its efficiency is decreased by drug administration.

This “microeconomics of metabolism” will serve as a macroscopic phenomenology to predict the metabolic responses against environmental operations. In particular, it offers a universal relationship between the metabolic responses against drug administrations and changes in nutrient availability.

Venue: via Zoom

Event Official Language: English

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