iTHEMS Weekly News Letter

Seminar Report

Biology Seminar by Dr. Lukasz Kusmierz on August 5, 2020


On 5th August, Ph.D. Lukasz Kusmierz ( RIKEN Center for Brain Science ) gave a talk at the iTHEMS Biology Seminar. Dr. Kusmierz introduced us to his work that modeling of heavy tails in the distribution of synaptic weights in the brain. His modeling, called "Cauchy network" which is based on the Cauchy distribution, has been successful in recreating biologically distributions. It could serve as a useful framework for checking the effects of synaptic heavy tails in various scenarios. His research will be a major step forward in the future of neuroscience. Thank you very much, Lukasz!

Upcoming Events


iTHEMS Theoretical Physics Seminar

Lefschetz-thimble inspired analysis of the Dykhne–Davis–Pechukas method and an application for the Schwinger Mechanism

August 21 at 13:00 - 14:30, 2020

Dr. Takuya Shimazaki (Researcher, Hadron Theory Group, The University of Tokyo)

Dykhne–Davis–Pechukas (DDP) method is a common approximation scheme for the transition probability in two-level quantum systems, as realized in the Landau–Zener effect, leading to an exponentially damping form comparable to the Schwinger pair production rate. We analyze the foundation of the DDP method using a modern complex technique inspired by the Lefschetz-thimble method. We derive an alternative and more adaptive formula that is useful even when the DDP method is inapplicable. As a benchmark, we study the modified Landau–Zener model and compare results from the DDP and our methods. We then revisit a derivation of the Schwinger Mechanism of particle production under electric fields using the DDP and our methods. We find that the DDP method gets worse for the Sauter type of short-lived electric pulse, while our method is still a reasonable approximation. We also study the Dynamically Assisted Schwinger Mechanism in two methods.

Venue: via Zoom

Event Official Language: English

Special Lecture

Tetsuo Hatsuda × Yoshinori Ohsumi × Sayaka Oki Online Discussion: "The Usefulness of 'Useless' Knowledge" Presented by iTHEMS & academist

August 22 at 13:00 - 15:30, 2020

Dr. Tetsuo Hatsuda (Program Director, iTHEMS)
Prof. Yoshinori Ohsumi (Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology)
Prof. Sayaka Oki (Graduate School of Economics, Department of Socio-Economic System, Nagoya University)



Venue: via Zoom

Event Official Language: Japanese


Forefront of Modern Science: Frontiers in Mathematics, Astronomy, Physics, Biology and Computation thumbnail

Forefront of Modern Science: Frontiers in Mathematics, Astronomy, Physics, Biology and Computation

October 2 at 16:20 - 17:50, 2020

Dr. Tetsuo Hatsuda (Program Director, iTHEMS)
Dr. Yuka Kotorii (Visiting Scientist, iTHEMS / Associate Professor, Mathematics Program, Graduate School of Advanced Science and Engineering, Hiroshima University / Visiting Scientist, Mathematical Analysis Team, RIKEN Center for Advanced Intelligence Project (AIP))
Dr. Shigehiro Nagataki (Deputy Program Director, iTHEMS / Chief Scientist, Astrophysical Big Bang Laboratory, RIKEN Cluster for Pioneering Research (CPR))
Dr. Makiko Nio (Senior Researcher, RIKEN Nishina Center for Accelerator-Based Science (RNC))
Dr. Ryosuke Iritani (Research Scientist, iTHEMS)
Dr. Ai Niitsu
Dr. Shigenori Otsuka (Research Scientist, iTHEMS / Research Scientist, Data Assimilation Research Team, RIKEN Center for Computational Science (R-CCS))
Dr. Emi Yukawa (Assistant Professor, Department of Physics, Faculty of Science Division I, Tokyo University of Science)

Venue: Changed to Zoom

Event Official Language: Japanese

Paper of the Week

Week 2 of August


Title: Artificial magnetic field for synthetic quantum matter without breaking time reversal symmetry
Author: Tomoki Ozawa

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