Featured News
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Behavioral Ecology of Plants: their sensory system, communication, memory, and response
Editor: The Society for the Study of Species Biology Language: Japanese Ryosuke Iritani (Research Scientist, iTHEMS) is among the authors. How do plants perceive the world, and how do plants behave? This book is a compilation of the most recent plant environmental response research by up-and-coming scientists for beginners.
2023-01-30
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Become a scientist who studies what you love !! [Chapter of Universe]
Cooperation / RIKEN Language: Japanese Five scientists explain the fascinating aspects of cutting-edge space research! Shigehiro Nagataki (Deputy Program Director, iTHEMS) and Naritaka Oshita (Special Postdoctoral Researcher, iTHEMS) are among the authors.
2023-01-24
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RIKEN NEWS: The Power of Open Science to Defeat Pandemics
Catherine Beauchemin (Deputy Program Director, iTHEMS) is interviewed in the Winter issue of RIKEN NEWS 2023. COVID-19 can only transmit if an infected person infects an uninfected person. So if 100% of sick people stayed home, there would be zero new cases, and COVID-19 would be over. Since transmission relies on the behaviour of each individual, to manage or even end COVID-19 requires the cooperation of every person in society. This is the big challenge we continue to face even now. Misinformation has become a big problem in society. People trust their own opinion and that of their friends and family more than facts. There is also a tendency to distrust government officials, pharmaceutical companies, news media and scientists. Sometimes it is true that such people or organizations will lie or exaggerate, so it is reasonable and important for a person to be skeptical. In fact, skeptical thinking is essential in science: we need to open our mind to new results, especially those that contradict our assumptions and hypotheses. So what can be done? I think the best way to combat misinformation and build a lasting trust with the public is complete transparency, by openly (free/re-usable) sharing data and scientific analyses with the general public, so people around the world can independently verify the facts. To read more, please see the related link.
2023-01-04
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Ryosuke Iritani wrote an essay for The Big Issue Japan 445
Ryosuke Iritani (Research Scientist, iTHEMS) wrote an essay for The Big Issue Japan, and the latest volume (vol 445) is just published on 15th December. The Big Issue is a magazine dedicated to supporting people in difficult circumstances and helping them achieve self-reliance. Each issue costs 450 yen, out of which 230 yen is the direct income of the street sales staff. Ryosuke's comment: The essay is about my “third place,” a place separated from home and workplace for me. I hope as many people as possible take it a read and support the people!
2022-12-27
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Four Perspectives on Neutron Stars, Pulsars, and Magnetars
The recent work [1] on X-ray bursts from the neutron stars led by our colleague, Akira Dohi (Visiting Scientist, iTHEMS), was featured in the article "Four Perspectives on Neutron Stars, Pulsars, and Magnetars" appeared in Research highlights from the Journals of the American Astronomical Society (see related link below).
2022-12-05
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Universal Force Appearing in Quantum Fluids at Cryogenic Temperatures - Intermolecular Force in Atomic Superfluids Guided by Quantum Fluctuation
The concept of "forces acting between materials," as exemplified by the universal law of gravitation, has continued to occupy an important position in physics. An international research group including Masaru Hongo (Assistant Professor, Faculty of Science, Niigata University / Visiting Scientist, RIKEN iTHEMS) and Keisuke Fujii (Postdoctoral Researcher, University Heidelberg, Germany) have revealed from theoretical calculations that the same intermolecular force known as van der Waals force acts between particles floating in a quantum fluid at cryogenic temperatures over long distances. Atomic groups cooled to near absolute zero (several tens of nano-Kelvin) by laser technology have attracted attention in recent years as a system in which quantum states can be controlled with high precision, and they are an ideal stage for investigating forces in the microscopic world. This research has newly revealed that a universal long-range force due to quantum fluctuation acts on impurity particles in atomic superfluids realized at cryogenic temperatures. For more details, please visit Niigata University's website from the related link below.
2022-12-02
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Naritaka Oshita presented his talk at the 12th Koshien of Science (Oita tournament) on November 3, 2022
The 12th Koshien of Science (Oita tournament), a scientific competition for high school students in Oita prefecture, was held on 3rd November 2022 at Oita city. Naritaka Oshita from iTHEMS presented his talk on “Black Holes Veiled in Mystery” after the competition. More than 200 high school students from Oita prefecture attended. Oshita talked about the history of science, recent progress, and remaining mysteries of black holes. A student asked a unique question “What if we fall into a black hole? Can our consciousness be recovered from the hole?”. Another student asked, “How can it be possible to detect the signal from a ringing black hole?”. The audience enjoyed the stimulating talk and questions from the students. During the competition, Oshita and an iTHEMS assistant Tomoko Iwanami observed the competition, where some students built their toy cars in each group and competed in a race.
2022-11-10
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Science Agora 2022 is held November 4-6, 2022
Science Agora 2022 is held online and in person in the period Nov. 4-6, 2022. There will be many fun sessions that you can join in person or online. There are English sessions too. RIKEN will have a session "Envisioning Futures: Navigating the research landscape with senior women researchers" in which Tetsuo Hatsuda from iTHEMS is one of the speakers. Enjoy !
2022-11-04
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Probing Quark Matter with Gravitational Waves - Reading Traces of Ultra-Dense Matter from Gravitational Waves after Neutron Star Mergers
An international research group including Yongjia Huang (Student Trainee, iTHEMS) and Shigehiro Nagataki (Deputy Program Director, iTHEMS) has performed numerical simulations based on general relativity for the merger of binary neutron stars and shown that the waveform of gravitational waves emitted after the merger provides detailed readings of the properties of ultra dense matter with a density of over 1 trillion kg per cm<sup>3</sup>. This research result is expected to contribute to the clarification of the internal structure of neutron stars and the properties of ultra-dense matter in gravitational wave astronomy. For details, please see the related link.
2022-10-27
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The RIKEN-Berkeley Center was featured in RIKEN Overseas Office Newsletter
The RIKEN-Berkeley Center was featured in the Oct. 2022 issue of "News from RIKEN's Overseas Offices". The title of the article written by Adam Phillips in the RIKEN International Affairs Division is "What makes institutional international collaborations work?". Enjoy the article!
2022-10-25
Videos
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What about climate change in actuality?
Odd couples of interdisciplinary research
Khovanov homology theory - an introduction to categorification by Dr. Taketo Sano on May 13, 2022
Fundamentals Fest, mini Pre-event on Science "Exploring and Bridging: The Potential of Basic Science"
In Search of Pc pentaquark - Simulate Hadron Interactions with FUGAKU
AAS Journal Author Series: Hirotaka Ito on 2021ApJ…918...59I
Will Useless Knowledge Change the Future? - What is the Black Hole Recorder?
RIKEN 2019 (in Japanese)
Physical and local observables in gravitational theory
Can you hear the shape of a drum?
Quantum many-body physics with cold atoms
complexity in non-unitary dynamics of photons
Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) is an international research program at RIKEN. It facilitates close collaborations among researchers from different disciplines in theoretical, mathematical and computational sciences. The ultimate goal of iTHEMS is to unravel the mystery of the Universe, matter, and life, as well as to solve key problems in modern society through interdisciplinary approaches.
Upcoming Events
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SeminarWarming reduces the density-dependent divergence in emergence time for two competing parasitoid species
March 23 (Thu) at 16:00 - 17:00, 2023
Dr. Midori Tuda (Associate Professor, Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University)
Climate change is expected to directly affect ectothermic species through their sensitivity to temperature, with cascading effects on populations and communities. Here we experimentally tested predictions from two non-exclusive hypotheses concerning the impacts of elevated temperature (+2°C) on interactions between a single host species (the azuki bean beetle) and two species of parasitoid wasps. We hypothesized that increasing temperature shortens the time that the host is vulnerable to parasitoid attack. This change in available resource should heighten intra- and interspecific competition among parasitoids, which could induce divergence in emergence times. We found that intraspecific competition of both parasitoid species was more intense than interspecific competition irrespective of temperature. The difference (d) in the emergence times of the two parasitoid species increased with the density of each parasitoid but decreased at the elevated temperature. Both parasitoids emerged sooner at the elevated temperature and experienced a reduction in body size. Thus, high levels of intraspecific competition (along with the consequent reduction in body size) may have attenuated the intensity of interspecific competition at the elevated temperature despite a reduction in the differentiation of emergence times.
Venue: via Zoom
Event Official Language: English
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OthersiTHEMS NOW & NEXT FY2022
March 29 (Wed) at 9:30 - 15:45, 2023
Dr. Eiji Inoue (Special Postdoctoral Researcher, iTHEMS)
Dr. Jeffrey Fawcett (Senior Research Scientist, iTHEMS)
Dr. Hidetoshi Taya (Special Postdoctoral Researcher, iTHEMS)
Dr. Naritaka Oshita (Special Postdoctoral Researcher, iTHEMS)
Dr. Takumi Doi (Senior Research Scientist, iTHEMS)Program: 9:30-10:00 Keynote Talk by Eiji Inoue 10:00-10:30 Keynote Talk by Jeffrey Fawcett 10:35-11:05 Keynote Talk by Hidetoshi Taya 11:05-11:35 Keynote Talk by Naritaka Ohshita 11:40-12:10 Keynote Talk by Takumi Doi 12:30-13:10 Lunch Time Session on Research Ethics 13:15-13:45 Working Group Report 13:45-14:20 Study Group Report 14:30-15:30 Panel Discussion on future of iTHEMS 15:30-15:45 Concluding Remarks by the Director
Venue: via Zoom
Event Official Language: English
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Seminar
Asymmetric enzyme kinetics of F1-ATPase resulted from asymmetric allosterism
March 30 (Thu) at 16:00 - 17:00, 2023
Dr. Yohei Nakayama (Assistant Professor, Department of Applied Physics, Graduate School of Engineering, Tohoku University)
Bio-molecular machines play various roles in cells where thermal fluctuation is dominant. Since artificial molecular machines are far behind bio-molecular machines for the present, we should begin with understanding how bio-molecular machines are designed to play their roles. We examine the motion of a bio-molecular machine, F1-ATPase, in single molecule experiments. In particular, we focus on the operation of F1-ATPase as ATP synthase in addition to as molecular motor. In this seminar, I talk about the enzyme kinetics, dependence of reaction rate on substrate concentration, of F1-ATPase in ATP synthesis. The experimental result shows that the enzyme kinetics of F1-ATPase in ATP synthesis exhibits weaker dependence on substrate concentration than the ordinary Michaelis-Menten kinetics, whereas that in ATP hydrolysis follows Michaelis-Menten kinetics. Therefore, the enzyme kinetics of F1-ATPase turned out to be asymmetric between ATP synthesis and hydrolysis. We analyzed this asymmetry based on a potential switching model, totally asymmetric allosteric model, whose characteristic is asymmetry in angular dependence of binding rates of substrates. It was shown that the totally asymmetric allosteric model may reproduce the experimental results, where the asymmetry of binding rates is essential. We also discuss physiological roles that the asymmetry of enzyme kinetics may play.
Venue: via Zoom
Event Official Language: English
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Seminar
Gauge-equivariant neural networks as preconditioners in lattice QCD
April 6 (Thu) at 13:30 - 15:00, 2023
Prof. Tilo Wettig (Professor, Universität Regensburg, Germany)
We demonstrate that a state-of-the-art multi-grid preconditioner can be learned efficiently by gauge-equivariant neural networks. We show that the models require minimal re-training on different gauge configurations of the same gauge ensemble and to a large extent remain efficient under modest modifications of ensemble parameters. We also demonstrate that important paradigms such as communication avoidance are straightforward to implement in this framework.
Venue: Common Room #246-248 (Main Venue) / via Zoom
Event Official Language: English
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ColloquiumEmergence of Extreme Universe from Quantum Information
April 17 (Mon) at 16:00 - 17:30, 2023
Prof. Tadashi Takayanagi (Professor, Yukawa Institute for Theoretical Physics, Kyoto University)
Recently, a new interpretation of gravitational spacetime in terms of quantum entanglement has been obtained. The idea of holography in string theory provides a simple geometric computation of entanglement entropy. This generalizes the well-known Bekenstein-Hawking formula of black hole entropy and strongly suggests that a gravitational spacetime consists of many qubits with quantum entanglement. Also a new progress on black hole information problem has been made recently by applying this idea. I will explain these developments in this colloquium.
Venue: via Zoom
Event Official Language: English
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Seminar
Towards EeV Neutrino Astronomy with GRAND
April 18 (Tue) at 14:00 - 15:00, 2023
Dr. Kumiko Kotera (Associate Professor, Institute of Astrophysics, France)
We are living exciting times: we are now able to probe the most violent events of the Universe with diverse messengers (cosmic rays, neutrinos, photons and gravitational waves). One challenge to complete the multi-messenger picture resides in the highest energies, as no ultra-high energy neutrinos have been observed yet. This challenge could be undertaken by the GRAND (Giant Radio Array for Neutrino Detection) project, which aims at detecting ultra-high energy particles, with a colossal array of 200'000 antennas over 200'000 km2, split into ~20 sub-arrays of ~10'000 km2 deployed worldwide. In this talk, we will present preliminary designs and simulation results, plans for the ongoing, staged approach to construction, and the rich research program made possible by the proposed sensitivity and angular resolution.
Venue: Common Room #246-248 / via Zoom
Event Official Language: English
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Seminar
X-ray study on the synchrotron emission in Kepler's SNR
May 19 (Fri) at 14:00 - 15:00, 2023
Dr. Vincenzo Sapienza (Ph.D. Student, Department of Physics, Graduate School of Science, The University of Tokyo)
Synchrotron X-ray emission in young supernova remnants (SNRs) is a powerful diagnostic tool to study the population of high energy electrons accelerated at the shock front. We performed a spatially resolved spectral analysis of the young Kepler's SNR, where we identify two different regimes of particle acceleration. In the north, where the shock interacts with a dense circumstellar medium (CSM), we found a more efficient acceleration than in the south, where the shock velocity is higher and there are no signs of shock interaction with dense CSM. We also studied the temporal evolution of the synchrotron flux, from 2006 to 2014. A number of regions show a steady synchrotron flux and equal cooling and acceleration times. However, we found some regions where we measured a significant decrease in flux from 2006 to 2014. Our results display a coherent picture of the different regimes of electron acceleration observed in Kepler's SNR. Also If I will have time during the seminar it will be nice to present also some preliminary results I will have in the SN 1987A project.
Venue: Common Room #246-248 / via Zoom
Event Official Language: English
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SeminarSpectral correlations and scrambling dynamics in Sachdev-Ye-Kitaev type models
May 30 (Tue) at 13:30 - 15:00, 2023
Dr. Masaki Tezuka (Assistant Professor, Division of Physics and Astronomy, Graduate School of Science, Kyoto University)
Note: Due to unexpected trouble, we have made the decision to postpone the seminar scheduled for February 21 to May 30. Sorry for the trouble. Abstract: The Sachdev-Ye-Kitaev (SYK) model, proposed in 2015, is a quantum mechanical model of N Majorana or complex fermions with all-to-all random four-body interactions. The model has attracted significant attention over the years due to its features such as the existence of the large-N solution with maximally chaotic behavior at low temperatures and holographic correspondence to low-dimensional gravity. The sparse version of the SYK model reproduces essential features of the original model for reduced numbers of disorder parameters. We recently proposed [1] a further simplification, where we set the nonzero couplings to be +1 or -1 rather than sampling from a continuous distribution such as Gaussian. This binary-coupling model exhibits strong correlations in the spectrum, as observed in the spectral form factor, more efficiently in terms of the number of nonzero terms than in the Gaussian distribution case. We also discuss the scrambling dynamics with the binary-coupling sparse SYK model, comparing the model with the original model as well as the SYK model with random two-body terms [2], where the localization of the many-body eigenstates in the Fock space has been quantitatively studied [3,4].
Venue: Common Room #246-248 / via Zoom
Event Official Language: English
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Workshop6th Workshop on Virus Dynamics
July 4 (Tue) - 6 (Thu), 2023
Prof. Catherine Beauchemin (Deputy Program Director, iTHEMS)
Prof. Shingo Iwami (Professor, Graduate School of Science, Nagoya University)The Workshop on Virus Dynamics is an international meeting held every 2 years. It brings virologists, immunologists, and microbiologists together with mathematical and computational modellers, bioinformaticians, bioengineers, virophysicists, and systems biologists to discuss current approaches and challenges in modelling and analyzing different aspects of virus and immune system dynamics, and associated vaccines and therapeutics. This 6th version of the workshop builds on the success of previous ones held in Frankfurt (2013), Toronto (2015), Heidelberg (2017), Paris (2019) and virtually (2021). It is supported by the Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) program at RIKEN, by Nagoya University, and by the Japan Science and Technology Agency. Up-to-date information and registration is available via the website. The workshop is for in-person participation only (no virtual or hybrid option).
Venue: Noyori Conference Hall, Higashiyama Campus, Nagoya University
Event Official Language: English
Opportunities
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Seeking a few Postdoctoral Researchers (RIKEN-Berkeley Fellow associated with N3AS) (W22284)
Deadline: Open until filled
Postdoctoral Researcher (RIKEN-Berkeley Fellow associated with N3AS), a few positions. Theoretical works associated with neutrino physics, nucleosynthesis, dense matter and neutron stars, dark matter, astrophysical simulations, lattice QCD simulations and related fields. Successful applicants will work and spend the first three months at the RIKEN Wako campus, and the remainder of the years at the RIKEN Berkeley Center at the University of California, Berkeley on a long term business trip. The appointments of the RIKEN Berkeley Fellow are made through RIKEN iTHEMS.
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Seeking Postdoctoral Researcher, Research Scientist and Senior Research Scientist (W22219)
Deadline: Open until filled
Postdoctoral Researcher, Research Scientist and Senior Research Scientist, about 10 in total. Depending on experience, performance and ability, they are employed as postdoctoral researchers (3-year term), research scientists (5-year term) or senior research scientists (7-year term). This call is for researchers to work in iTHEMS in collaboration with one of the following laboratories participating in RIKEN Quantum (work concurrently with one of the following laboratories as needed), and to carry out research in quantum computational science and related fields. RIKEN Quantum aims to promote fundamental science based on quantum computational science, and the successful candidate will not only conduct top-level research on their own topic, but also contribute to building common ground in mathematics, physics, chemistry, life sciences, information sciences, computational science, humanities and social sciences through quantum computational science.
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Seeking a few Research Scientists or Senior Research Scientists (W22160)
Deadline: Open until filled
Research Scientist or Senior Research Scientist, a few positions. iTHEMS is seeking Research Scientist(s) or Senior Research Scientist(s) in theoretical astrophysics, astronomy, cosmology, and related fields. The successful applicants are expected not only to pursue top-level research in their own research focus but also to lead interdisciplinary collaborations among different fields such as mathematics, physics, chemistry, biology, information sciences, computational sciences, and social sciences, under the concept of iTHEMS.
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Seeking a few Female Research Scientists or Female Senior Research Scientists (W22158)
Deadline: Open until filled
Female Research Scientist or Female Senior Research Scientist, a few positions. iTHEMS is seeking a few Female Research Scientists or Female Senior Research Scientists to conduct theoretical research in the fields of natural sciences, mathematical sciences, or humanities and social sciences. The scope of responsibilities will be commensurate with the applicant's career level. The applicants will be expected not only to pursue top-level research in their field but also to collaborate actively with an interdisciplinary group of researchers across fields such as mathematics, physics, chemistry, life sciences, engineering, computational sciences, information sciences, and humanity and social sciences, under the concept of iTHEMS.
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Seeking a few Postdoctoral Researchers (W22157)
Deadline: Open until filled
Postdoctoral Researcher, a few positions. We invite applications for postdoctoral researcher positions at RIKEN iTHEMS in the field of theoretical cosmology. The successful applicants are expected not only to conduct high-quality research in their own field but also to participate in interdisciplinary collaborations among different fields including, but not limited to, mathematics, physics, chemistry, life sciences, engineering, computational sciences, information sciences, social sciences, and machine learning sciences, under the concept of iTHEMS.
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Seeking a few Research Scientists or Senior Research Scientists (W22142)
Deadline: Open until filled
Research Scientist or Senior Research Scientist, a few positions. iTHEMS is seeking research scientist(s) or senior research scientist(s) in quantum computational science, quantum information science and related fields. The successful applicants are expected not only to pursue top-level research in their own research focus but also to lead interdisciplinary collaborations among different fields such as mathematics, physics, chemistry, biology, information sciences, computational sciences, and social sciences, under the concept of iTHEMS.
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Seeking a few Research Scientists or Senior Research Scientists (W22141)
Deadline: Open until filled
Research Scientist or Senior Research Scientist, a few positions. iTHEMS is seeking research scientist(s) or senior research scientist(s) in theoretical or applied information science, especially as it pertains to machine learning and data analysis. The successful applicants are expected not only to pursue top-level research in their own research focus but also to lead interdisciplinary collaborations among different fields such as mathematics, physics, chemistry, biology, information sciences, computational sciences, and social sciences, under the concept of iTHEMS.
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Seeking a few Research Scientists or Senior Research Scientists (W22140)
Deadline: Open until filled
Research Scientist or Senior Research Scientist, a few positions. iTHEMS is seeking research scientist(s) or senior research scientist(s) in mathematical sciences including pure mathematics, applied and industrial mathematics. The successful applicants are expected not only to pursue top-level research in their own research focus but also to lead interdisciplinary collaborations among different fields such as mathematics, physics, chemistry, biology, information sciences, computational sciences, and social sciences, under the concept of iTHEMS. This time, we encourage junior applicants who have high ability in mathematical sciences.
Latest News
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2023-03-16
Paper of the WeekWeek 3, March 2023
Title: Coupled Hénon Map, Part II: Doubly and Singly Folded Horseshoes in Four Dimensions Author: Jizhou Li, Keisuke Fujioka, Akira Shudo arXiv: http://arxiv.org/abs/2303.06824v1 Title: Coupled Hénon Map, Part I: Topological Horseshoes and Uniform Hyperbolicity Author: Keisuke Fujioka, Ryota Kogawa, Jizhou Li, Akira Shudo arXiv: http://arxiv.org/abs/2303.05769v1
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2023-03-16
Hot Topic
Farewell message from Dr. Hiroshi Yokota
Our colleague Hiroshi Yokota has moved to the Graduate School of Human and Environmental Studies, Kyoto University as a CREST postdoctoral researcher from March 1, 2023. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Hiroshi Yokota: I had worked at iTHEMS as a postdoctoral researcher for almost 4 years. I would like to thank all the iTHEMS members for the valuable discussions on their researches including my own research. Moreover, in iTHEMS, I had very good opportunities to attend the exciting seminars and colloquiums which gave me brilliant ideas from the various fields: physics, biology, mathematics and information. I enjoyed the discussions, the seminars and the colloquiums in iTHEMS. I also would like to thank all assistants who gave us the comfortable research environment. Fortunately, I am allowed to be the visiting scientist in iTHEMS. I hope to discuss with iTHEMS members in future also.
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2023-03-15
Hot Topic
Farewell message from Dr. Naritaka Oshita
Our colleague Naritaka Oshita will move to the Kyoto University as a Hakubi assistant professor from April 1st. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Naritaka Oshita: I enjoyed studying gravity and black holes while being a part of iTHEMS and participating in some iTHEMS events and activities. As of the end of this March, it has been almost two years since I started my second postdoc at iTHEMS as an SPDR fellow in 2021 April. From 2023 April, I will be a Hakubi assistant professor at Kyoto University and will start my exciting new research to understand the mystery of gravity. I enjoyed discussing with many iTHEMS members who are working on physics, biology, mathematics, (quantum) information theory, etc. I thank all faculties, researchers, and students at iTHEMS for having exciting discussions with me! iTHEMS assistants have been contributing to this group to improve the research environment at iTHEMS and they kindly helped me a lot when I needed their help and was in trouble. I appreciate all the assistants at iTHEMS for their support and for having fun conversations! Again, thank you to all members at iTHEMS for everything! I will still be a part of iTHEMS as a visiting researcher. I hope I can have exciting discussions and conversations with you in the future. See you again!