Press Release

44 news

2022-08-29
Press Release

Is it possible to shorten isolation of people infected with new coronavirus? -Development of a simulator to verify the timing of quarantine termination

Professor Shingo Iwami (Graduate School of Science, Nagoya University / Visiting Scientist, iTHEMS), in collaboration with Assistant Professor Keisuke Ejima (Indiana University, USA), has developed a new simulator (computer simulation) to verify when to end isolation of persons infected with a novel coronavirus (COVID-19) through antigen testing. This will allow us to propose a flexible and safe isolation strategy that can terminate isolation of COVID-19-infected patients as early as possible with negative results of a predetermined number of antigen tests. Isolation of infected patients is an important means of preventing the spread of infection. While prolonged isolation reduces the risk of secondary infection, it also places various burdens on the person being isolated and the society that supports them. Using the simulator they have developed, the research group has successfully calculated "the risk of (prematurely) terminating isolation of infectious patients" and "the duration of unnecessary isolation of patients who are no longer infectious (the burden associated with isolation)." As a result, we are now able to propose an appropriate isolation strategy that takes into account individual differences and uses antigen testing to simultaneously reduce risk and burden. As we enter the era of with-colonization, in which social activities are resumed and maintained while infection prevention measures are thoroughly implemented, the successful use of antigen testing will allow for the safe implementation of educational and social activities. In contrast to the current situation where different isolation standards based on clinical and epidemiological data and empirical rules are adopted in different countries, this study is expected to contribute to the establishment of flexible isolation guidelines based on mathematical models, which are required not only in Japan but also worldwide. For more details, please visit the Nagoya University research results dissemination site from the related link.
2022-06-06
Press Release

Common Laws of Evolution and Ecological Dynamics

The research team of Kyosuke Adachi (Special Postdoctoral Researcher, iTHEMS / Special Postdoctoral Researcher, Nonequilibrium Physics of Living Matter RIKEN Hakubi Research Team, RIKEN Center for Biosystems Dynamics Research (BDR)), Ryosuke Iritani (Research Scientist, iTHEMS) and Ryusuke Hamazaki (Senior Research Scientist, iTHEMS / RIKEN Hakubi Team Leader, Nonequilibrium Quantum Statistical Mechanics RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research (CPR)) have proposed a broadly valid formula for theoretical models of evolutionary and ecological population dynamics using methods from information theory and statistical physics. The results of this research are expected to lead to a unified framework for understanding complex population dynamics in evolutionary and ecological systems over time. For more information, please see the related link.
2022-05-09
Press Release

Discovering Speed Limits for Macroscopic Transitions - A Unified Approach Based on the Equation of Continuity

Ryusuke Hamazaki (RIKEN Hakubi Team Leader, Nonequilibrium Quantum Statistical Mechanics RIKEN Hakubi Research Team / Senior Research Scientist, iTHEMS) has discovered a new inequality for the “speed limit," or transition rate, which is useful for physical processes that involve "macroscopic transitions". The research results are expected to have implications for nonequilibrium statistical mechanics, including the time scale of thermalization of quantum many-body systems. They are also expected to contribute to the fundamental understanding of quantum technology, e.g., the control of macroscopic quantum systems, which has become important in recent years. Please see related link for more details.
2022-05-09
Press Release

Clear Visualization of Lamb Waves from Tonga's Undersea Volcano Eruption -The Full Picture of the Waves Captured by the Himawari-8

Takemasa Miyoshi (Deputy Program Director, iTHEMS / Team Leader, Data Assimilation Research Team, RIKEN Center for Computational Science (R-CCS)) and Shigenori Otsuka (Research Scientist, iTHEMS / Research Scientist, Data Assimilation Research Team, RIKEN Center for Computational Science (R-CCS)) have developed an original method to clearly visualize "Lamb waves," a type of sound wave associated with Tonga's undersea volcanic eruption in January 2022, using images from the Himawari 8 meteorological satellite. Furthermore, we developed a method to automatically extract the Lamb waves from this image and clarified the relationship between the distribution of arrival times and ground pressure observations. The results of this research are expected to contribute to the scientific understanding and monitoring of atmospheric waves and associated tidal fluctuations caused by volcanic eruptions, and to the development of advanced simulations and future forecasting methods by integrating observation data with large-scale atmospheric and oceanographic calculations. Please see related links for more details.
2022-04-01
Press Release

RIKEN iTHEMS, the University of Tokyo and Kyoto University Launch New Inter-University Lecture Program Using Online Classes

The RIKEN (RIKEN) Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS), the College of Arts and Sciences of the University of Tokyo and the Faculty of Science of Kyoto University will launch a new inter-university collaborative online lecture system in April 2022, offering courses on various aspects of mathematical sciences to students in both faculties. In addition to faculty members from the University of Tokyo and Kyoto University, young researchers from RIKEN and other research institutes will give a series of lectures, which students can take as courses at their respective universities and earn credits. This new lecture format allows students to learn the fundamentals and applications of mathematical science, which form the foundation of modern society, from front-line researchers as early as their undergraduate years. At the same time, it enables the development of young human resources beyond the boundaries of universities. Active discussions between young researchers and students in class are expected to lead not only to the development of basic scientific research, but also to the development of human resources who will create innovations in society in the future. For more information, please see the related link.
2022-03-31
Press Release

Chaos theory provides hints for controlling the weather

A research team led by Takemasa Miyoshi (Deputy Program Director, iTHEMS) has devised a new theory of control simulation experiments to study weather controllability. Under a project led by the RIKEN Center for Computational Science, researchers have used computer simulations to show that weather phenomena such as sudden downpours could potentially be modified by making small adjustments to certain variables in the weather system. They did this by taking advantage of a system known as a “butterfly attractor” in chaos theory, where a system can have one of two states—like the wings of a butterfly—and that it switches back and forth between the two states depending on small changes in certain conditions. To read more, please see the related link.
2022-03-09
Press Release

Negative string tension of a higher-charge Schwinger model via digital quantum simulation

It is known that particles with the same positive (negative) charge usually are repulsed, while particles with opposite positive and negative charges are attracted to each other. Recently, however, it was pointed out that such "common knowledge" that an attractive force acts between particles with opposite positive and negative charges does not always hold true under special situations. The research group succeeded in realizing a situation in which a repulsive force acts between particles with opposite charges in a one-dimensional quantum system called the Schwinger model by numerical simulation. This is a new application of the algorithm used in quantum computers (quantum algorithm), and is expected to contribute to our understanding of important problems such as the time evolution and the phase structure of the early universe in finite density regions, which have been difficult to analyze using conventional methods. For more details, please see the press release article from Kyoto University at related links.
2022-03-07
Press Release

Simulation Improves Accuracy of Forecasting Heavy Rainfall in Linear Precipitation Zones -What if the most advanced weather radar could cover all of Kyushu-

A joint research team led by Dr. Takemasa Miyoshi, Team Leader of the Data Assimilation Research Team at the RIKEN Center for Computational Science (R-CCS) (Chief Scientist, Predictive Science Laboratory, Deputy Program Director, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS)), and Dr. Yasumitsu Maejima, Postdoctoral Researcher, has announced that simulation showed significant improvement of forecasting disastrous heavy rainfall in July 2020. The results of this study showed that the state-of-the-art phased-array weather radar can significantly improve the accuracy of forecasting heavy rainfall associated with linear precipitation zones. The results of this research are expected to improve the forecasting accuracy of linear precipitation zones, which are increasingly threatened by global warming, and to lead to the proposal of new forecasting techniques and observation systems to mitigate the damage. To read more, please see the related link.
2022-01-24
Press Release
Origin of Diverse Response Patterns in Signal Transduction - Determining Response Properties by Integrating Experiment and Theory

The ERBB family of receptors, consisting of ERBB1, ERBB2, ERBB3, and ERBB4, is a group of receptors that receive external signaling molecules. When the ERBB receptors receive signaling molecules, they bind to one another and induce phosphorylation reactions, leading to macroscopic responses such as cell proliferation and differentiation. However, it is difficult to measure the details of the binding and phosphorylation reactions of the ERBBs, and it has not been known how the various responses to signals are produced. In this study, we conducted experimental measurements using cells with various compositions of ERBBs and multiple signaling molecules and constructed a mathematical model, which incorporates all possible reactions of ERBBs. By applying the mathematical model, we succeed in explaining and predicting the experimental results on phosphorylation responses. Furthermore, we identified the reactions that play an essential role in the diversity of the phosphorylation responses. Our findings may allow us to control cell responses such as proliferation and differentiation in the future. For more details, please see the press release article from Kyoto University at related links.
2021-12-27
Press Release

Simplifying Complex Chemical Reaction Networks - a reduction method using homological algebra

A team of researchers, Yuji Hirono (Visiting Scientist, iTHEMS), Takashi Okada (Senior Research Scientist, iTHEMS), Hiroyasu Miyazaki (Senior Research Scientist, iTHEMS) and Yoshimasa Hidaka (Visiting Scientist, iTHEMS), has developed a new method for simplifying complex chemical reaction networks using a mathematical technique called “homological algebra”. Using this method, complex networks can be simplified while preserving their important features and their properties can be studied more efficiently. The research is conducted by a team of physicists, a mathematician, and a biologist, and demonstrates the effectiveness of a cross-disciplinary approach. To read more, please see the related link.
2021-12-15
Press Release

Universal chords played by black holes - Toward the verification of general relativity by black hole fluctuations

Naritaka Oshita (Special Postdoctoral Researcher, iTHEMS) has revealed the "universal combination" of vibration patterns of black holes that are most easily excited from theoretical calculations. This research result is expected to contribute to the measurement of the weight and rotation speed of black holes by observational data of space-time ripples (gravitational waves) propagating immediately after the merger of a binary black hole, and to the precise test of Einstein’s general theory of relativity. To read more, please see the related link (in Japanese).
2021-10-20
Press Release

Increased number of drought-responsive genes in a tropical rainforest tree, Shorea leprosula (Dipterocarpaceae)

A collaborative research group including Dr. Jeffrey Fawcett (Senior Research Scientist, iTHEMS) has sequenced the genome of a tropical tree species, Shorea leprosula (Dipterocarpaceae), which is important for the global environment and as an imported timber. Although the trees grow in tropical East Asia, which is blessed with abundant rainfall, they unexpectedly showed an increase in drought-responsive genes, revealing the importance of rare droughts in the tropics. Global environmental change is exacerbating large-scale drought associated with El Niño Southern Oscillations (ENSO) in the tropics, and it is expected that the results of this study will be applied toward sustainable forestry and tropical rainforest conservation. For more information, please visit the Yokohama City University website.
2021-09-17
Press Release

A New Mechanism to Explain Multispecies Coexistence in Plants - Evolutionary Rescue Caused by the Evolution of Self-Fertilization before Flowering

Koki Katsuhara (Assistant Professor, Okayama University; at the time: Kobe University), Yuuya Tachiki (Assistant Professor, Tokyo Metropolitan University), Ryosuke Iritani (Research Scientist, iTHEMS; at the time: University of California, Berkeley, University of Exeter) and Atsushi Ushimaru (Professor, Kobe University) performed simulations using an individual-based model and found that in two plant species that share the same species of pollinator and are in competition, evolutionary rescue occurs in which the evolution of higher self-fertilization rates in the rarer species results in an increase in population size, thereby promoting long-term coexistence between the two species. The results of this study add a new theory to explain why multiple flowering species can coexist in the same place, and also provide a new perspective for the evolution of diverse reproductive strategies in plants. Understanding the mechanisms that create and maintain plant diversity, which supports the basis of terrestrial ecosystems, is essential not only for understanding the origin of biodiversity, but also for forming a sustainable society in harmony with ecosystems, and is an important knowledge in both basic and applied aspects. For more information, please visit the Okayama University website at the related link.
2021-08-31
Press Release

Supercomputer Predicts Fascinating New Particle Charmed Di-Omega - A new page toward solving the puzzle of the 6-quark states has been added -

An international collaboration including Takuya Sugiura (Postdoctoral Researcher, iTHEMS) , Tetsuo Hatsuda (Program Director, iTHEMS), and Takumi Doi (Senior Research Scientist, Quantum Hadron Physics Laboratory, RNC) has theoretically predicted the existence of a new particle called Charmed Di-Omega which consists of six charm quarks. To read more, please see the related link (in Japanese).
2021-05-27
Press Release

First Clarification of the Network Structure of Money Flow

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.
2021-05-11
Press Release

Mystery of Wasps That Produce Few Males Solved

A collaborative research group, including Dr. Ryosuke Iritani (Research Scientist, iTHEMS), has solved the mystery of wasps that produce only a few percent of males. See related link for details.
2021-03-12
Press Release

The future may come when each of us can carry around a black hole as information storage device

-- Imagining and prototyping future information storage devices based on scientific theories.-- The first prototype of the Useless Prototyping Studio, "Black Hole Recorder," has been completed and is now on display at the National Museum of Emerging Science and Innovation from March 14 (Sun.) to 21 (Sun.), 2021. The "Useless Prototyping Studio", which uses seemingly useless prototypes to visualize the possibility that curiosity about the unknown can create the future, has created its first prototype, the "Black Hole Recorder," a future information storage device. The outline and background information are available on a special website released today, March 12. In addition, as an opportunity for the general public to view the recorder, it will be exhibited at the National Museum of Emerging Science and Innovation (Miraikan) in Koto-ku, Tokyo, from March 14 (Sunday), the birthday of Albert Einstein and the death anniversary of Stephen Hawking, the two scientists who developed the basic theory of black holes. The Black Hole Recorder is a prototype black hole storage device developed with an eye to the future where black holes can be controlled and used as a device to store information. Based on the motif of a phonograph, it implements a device that can record huge amounts of data. In addition to storing large amounts of information, it is also capable of retrieving the information it has captured. Since the invention of writing thousands of years ago, humans have evolved the media and technologies for recording information from paper, printing, photography, phonograph, video, and data. In recent years, developments have been made to see how large a quantity of information can be stored. And in the future, we can think of the possibility of a time when black holes can be used as information storage and carried around in our pockets.
2021-02-24
Press Release

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

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."
2021-02-10
Press Release

Developed a new theory "Diagrammatic expansion of information flows in stochastic Boolean networks"

A research collaboration of Dr. Fumito Mori (Assistant Professor, Education and Research Center for Mathematical and Data Science/Faculty of Design, Kyushu University) and Dr. Takashi Okada (Senior Research Scientist, RIKEN iTHEMS) has developed a new theory for "Diagrammatic expansion of information flows in stochastic Boolean networks". For more details, please see the related links.
2021-02-04
Press Release

Untangling the complexity of market competition in consumer goods—A complex Hilbert PCA analysis

A research collaboration of Prof. Makoto Mizuno (the Faculty of Commerce, Meiji University), Prof. Hideaki Aoyama (Senior Visiting Scientist, RIKEN iTHEMS) and others has developed a new econophysics method applicable to analyze marketing data. For more details, please see the related links.
2020-12-09
Press Release

RIKEN iTHEMS Launches "Useless Prototyping Studio" Project to Inspire the Human Mind with Seemingly Useless Prototypes

RIKEN iTHEMS Launches "Useless Prototyping Studio" Project to inspire the human mind with seemingly useless prototypes. The prototypes based on the theories/hypotheses of scientists embody the potential to transform the future. The first trailer "Can the black hole be an information storage in the future?" on the teaser site Published today. RIKEN iTHEMS will launch the "Useless Prototyping Studio", a project to inspire the human mind with seemingly useless prototypes on Wednesday, December 9. We also publish a project overview and a preview of the first prototype "Can the black hole be an information storage in the future?" on the teaser site, which is available on the same day. Project Overview "Useless Prototyping Studio" is a design studio that aims to create new relationships between science and the society by creating prototypes that look useless at first glance but inspire the human mind. Based on scientific theories/hypotheses derived from the "curiosity for the unknown" of scientists, we imagine the possibility of these theories/hypotheses to change the future, and visualize the potential of science for the future by materializing the prototypes. The studio will be led by RIKEN iTHEMS, with the creative boutiques "SCHEMA" and "addict" as initial partners. As the project progresses, the number of partners and participating members will be expanded. - Overview of "Useless Prototyping Studio" - [Name] Useless Prototyping Studio [URL] https://uselessprototyping.jp [Launch date] December 9, 2020 (Wednesday) to launch the teaser site [Theme] The theme of the first prototype: "What's inside the black hole?" [Prototype first announced] Scheduled for early March 2021 [Project Participation Members] 　RIKEN iTHEMS 　SCHEMA 　addict
2020-11-19
Press Release

The longest "rulers" in the universe -- Gamma-Ray Bursts associated with Kilonovae are the new standard candles

An international collaborative research group led by Maria Dinotti (Senior Research Scientist, iTHEMS) and Shigehiko Nagataki (Deputy Program Director, iTHEMS) has discovered that gamma-ray bursts (GRBs), which occur simultaneously with kilonovae, are effective as standard candles for measuring the distance of the universe. The results of this research show the potential to make use of GRBs for cosmology in the near future, to estimate the amount of dark energy and dark matter in the universe.
2020-11-09
Press Release

Online event "Do you really know what the black hole is?" (iTHEMS x academist)

On December 6, 2020, iTHEMS and academist will have an online event "Do you really know what the black hole is?" Forefront physicists will explain theories and observations of blackholes behind the 2020 Nobel Prize in Physics.
2020-10-27
Press Release

Established RIKEN SUURI CORPORATION with investment from RIKEN, RIKEN Innovation Co., Ltd., and JSOL

-Building a New Innovation Platform through Collaboration between Academia and Business- RIKEN, RIKEN Innovation Co., Ltd. and JSOL Corporation have jointly established RIKEN SUURI CORPORATION, effective October 1, 2020. This is RIKEN's first investment in a venture. RIKEN, Japan's only research institute for the natural sciences, has a wealth of research and development capabilities that have been cultivated over its more than 100-year history, the first product to be brought to the market by RIKEN's investment was neither state-of-the-art equipment nor a drug, but "the best brains in the mathematical sciences itself". RIKEN SUURI CORPORATION aims to be a company that maximizes the use of mathematical sciences to solve the fundamental problems of society.
2020-10-27
Press Release

Research Collaboration Agreement Signed to Expand the Field of Multi-Messenger - RIKEN CPR, iTHEMS and ICRR The University of Tokyo

By October 22, RIKEN Cluster for Pioneering Research, iTHEMS and Institute for Cosmic Ray Research concluded a research collaboration agreement to further promote research cooperation in the field of multi-messenger cosmic ray physics, including joint research and personnel exchanges.
2020-08-03
Press Release

Tetsuo Hatsuda × Yoshinori Ohsumi × Sayaka Oki Online Discussion: "The Usefulness of 'Useless' Knowledge" will be held on August 22!

academist, Inc. and RIKEN iTHEMS are pleased to announce the presentation of "Tetsuo Hatsuda x Yoshinori Ohsumi x Sayaka Oki Online Discussion: "The Usefulness of ‘Useless' Knowledge" on Saturday, August 22, 2020 at 1:00 pm.
2020-07-10
Press Release

When adaptation promotes coexistence

Peafowl males have prominent ornaments, birds song for courtship, and flowers are beautiful and attractive for pollen transporters. Such characteristics appear to be adaptive at the level of individuals, but do not necessarily increase population growth rate. Therefore, these are, at the level of species, “wasteful”, making the species weaker to other species in competition for resources. Our collaboration group named this process as “intra-specific adaptation load,” and developed mathematical models, showing that strong intra-specific competition leads to a coexistence of a number of species that would have otherwise excluded each other (“competitive exclusion”). This new mechanism, which has been rarely considered in biodiversity research, may actually play a pivotal role in maintaining the biodiversity on earth.
2020-07-09
Press Release

Black Hole as a Quantum Field Configuration

A joint research team led by Yuki Yokokura, a senior researcher at the Interdisciplinary Theoretical and Mathematical Sciences Program at RIKEN, has theoretically described the interior of an evaporating black hole using quantum mechanics and general relativity. The results of this research will provide an insight into the nature of black holes, and are expected to provide a basic theory of "black hole engineering" that will utilize black holes as devices to store information in the distant future. The study was published in the online scientific journal Universe on June 4.
2020-06-26
Press Release

Light nucleus predicted to be stable despite having two strange quarks

Adding an exotic particle known as a Xi hyperon to a helium nucleus with three nucleons could produce a nucleus that is temporarily stable, calculations by RIKEN nuclear physicists have predicted1. This result will help experimentalists search for the nucleus and provide insights into both nuclear physics and the structure of neutron stars.
2020-03-19
Press Release

Merger between two stars led to iconic supernova -- Simulations suggest that two stars came together to form a blue supergiant, which subsequently exploded

A supernova in a nearby galaxy may have originated from an explosion of a blue supergiant formed by the merger of two stars, simulations by RIKEN astrophysicists suggest1. The asymmetric nature of this explosion may provide hints for where to look for the elusive neutron star birthed in this stellar cataclysm. A core-collapse supernova occurs when the core of a massive star can no longer withstand its own gravity. The core collapses in on itself, triggering a violent explosion that blasts away the star’s outer layers, leaving behind a neutron star or black hole. In 1987, astronomers saw a star explode in the Large Magellanic Cloud, one of our galaxy’s closest neighbors. Since then, scientists have intensively studied the aftermath of this supernova, known as SN 1987A, to understand the nature of the progenitor star and its fate. The progenitor of this type of supernova is usually a red supergiant, but observations have shown that SN 1987A was caused by a compact blue supergiant. “It has been a mystery why the progenitor star was a blue supergiant,” says Masaomi Ono at the RIKEN Astrophysical Big Bang Laboratory.
2020-03-05
Press Release

New Hypernucleus "Xi-Tetrabaryon" -- Unravelling the behavior of Xi-particle by high-precision computations

An international research group including Dr. Tetsuo Hatsuda (Program Director, iTHEMS), and Takumi Doi (Senior Research Scientist, iTHEMS / Quantum Hadron Physics Laboratory, RIKEN) has theoretically predicted the existence of a new hyper-nucleus (hypernucleus), the Xi-Tetrabaryon, consisting of one Xi-particle and three nucleons. Please see the related link for details
2019-09-04
Press Release

Genomic analysis of 370 Japanese Thoroughbred horses: the genetic background of why Thoroughbreds can run fast

Humans have been trying to improve Thoroughbreds by selectively breeding horses that can run fast. Each generation, a small number of males are selected to breed so that only these “elite” males can pass on their genes to the following generation. In this study, we examined how this continuous artificial selection has affected the evolution of the genomes of Thoroughbreds. First, we found that the genetic diversity is low in Thoroughbreds due to repeated inbreeding since even before the establishment of Thoroughbreds. Second, we found several regions that exhibit signatures of artificial selection. These regions typically show locally reduced genetic variation and should contain genes that are important for the athletic performance of Thoroughbreds. This study opens the way for genomic information to be utilized in the selective breeding of Thoroughbreds.
2019-08-02
Press Release

Is your Supercomputer Stumped? There May Be a Quantum Solution

The recent paper by Jason Chang* (iTHEMS/UCB/LBNL), Shigetoshi Sota* (R-CCS) and their collaborators in US, "Quantum annealing for systems of polynomial equations" (Nature Scientific Reports, 9 (2019) 10258), was press-released on Aug.1, 2019 with a headline - Is your Supercomputer Stumped? There May Be a Quantum Solution - (*) Both Jason and Shigetoshi are members of the iTHEMS QCoIn Working Group.
2019-04-11
Press Release

Observation of Quantized Heating Rate in Ultracold Topological Matter

An international collaboration of researchers from University of Hamburg, Université libre de Bruxelles, and RIKEN iTHEMS observed quantized heating rate, demonstrating a novel universal probe for topological states of matter. The experiment was performed using a gas of ultracold potassium atoms. The researchers looked for the difference in heating rate upong "shaking" the system clock-wise and counter-clock-wise, and confirmed that this different is quantized to the value of the "Chern number" of the system, a topological invariant characterizing a two-dimensional system. The experiment took place in Hamburg, with theoretical collaborations from theorists in Bruxelles and RIKEN iTHEMS.
2019-04-03
Press Release

Researchers pinpoint origin of photons in mysterious gamma-ray bursts

Scientists from the RIKEN Cluster for Pioneering Research and collaborators have used simulations to show that the photons emitted by long gamma-ray bursts—one of the most energetic events to take place in the universe—originate in the photosphere—the visible portion of the “relativistic jet” that is emitted by exploding stars.
2019-02-21
Press Release

Non-sinusoidal Waveform in Temperature-Compensated Circadian Oscillations

Shingo Gibo (Postdoctoral Researcher, iTHEMS) and Gen Kurosawa (Senior Research Scientist, iTHEMS) have published a press release.
2018-12-18
Press Release

Mystery of coronae around supermassive black holes deepens

Researchers from RIKEN and JAXA have used observations from the ALMA radio observatory located in northern Chile and managed by an international consortium including the National Astronomical Observatory of Japan (NAOJ) to measure, for the first time, the strength of magnetic fields near two supermassive black holes at the centers of an important type of active galaxies. Surprisingly, the strengths of the magnetic fields do not appear sufficient to power the “coronae,” clouds of superheated plasma that are observed around the black holes at the centers of those galaxies.
2018-10-16
Press Release

The First Telescope of a New Observatory for High-Energy Gamma-Ray Astronomy Makes its Debut

Several iTHEMS members are actively involved in a brand-new, cutting edge astronomical project, called the Cherenkov Telescope Array (CTA). CTA will be the foremost global observatory for very high-energy gamma-ray astronomy over the next decade and beyond and will be the first ground-based gamma-ray astronomy observatory open to the world-wide astronomical and particle physics communities. The scientific potential of CTA is extremely broad: from understanding the role of relativistic cosmic particles to the search for dark matter. With its ability to cover an enormous range in photon energy from 20 GeV to 300 TeV, CTA will improve on all aspects of performance with respect to current instruments. From iTHEMS, Susumu Inoue and Yoshiyuki Inoue in particular have been actively contributing to the science case studies of multi-messenger transient phenomena and supermassive black holes as members of the CTA Consortium. On Wednesday, 10 October 2018, more than 200 guests from around the world gathered on the northern array site of the CTA to celebrate the inauguration of the first prototype Large-Sized Telescope (LST). The telescope, named LST-1, is intended to become the first of four LSTs on the north site of the CTA Observatory, which is located on the existing site of the Instituto de Astrofisica de Canarias’ (IAC’s) Observatorio del Roque de los Muchachos located in the municipality of Villa de Garafia on the island of La Palma. The plan for the site also includes 15 Medium-Sized Telescopes (MSTs). The LSTs will expand the science reach to cosmological distances and fainter sources with soft energy spectra. Both the repositioning speed and the low energy threshold provided by the LSTs are critical for CTA studies of transient gamma-ray sources in our own Galaxy and for the study of active galactic nuclei and gamma-ray bursts at high redshift.
2018-09-11
Press Release

An unstable isotope Technetium-98 (98Tc) could be synthesized by neutrinos emitted from supernova explosions

A joint research group consisting of Masaomi Ono, a Research Scientist at RIKEN, and others has theoretically predicted that an unstable isotope Technetium-98 (98Tc) could be synthesized by neutrinos emitted from supernova explosions. Supernovae are important events in the evolution of stars and galaxies, but the details of how the explosions occur are still unknown. This research found a method to investigate the role of electron anti-neutrinos in supernovae. By measuring the amount of 98Ru (an isotope of Ruthenium) in meteorites, it should be possible to estimate how much of its progenitor 98Tc was present in the material at the time when the Solar System formed. The amount of 98Tc in turn is sensitive to the characteristics, such as temperature, of electron anti-neutrinos in the supernova process; as well as to how much time passed between the supernova and the formation of the Solar System. (This work appeared in Physical Review Letters on Sept. 4, 2018.) Caption: We can estimate the age of heavy elements in the primordial Solar System by measuring the traces left in meteorites by specific radioactive nuclei synthesized in certain types of supernovae. Credit: NAOJ (National Astronomical Observatory of Japan)
2018-07-26
Press Release

Diffuse x-ray emission from the northern arc of loop I observed with suzaku

The research team, including Yoshiyuki Inoue (Senior Research Scientist, iTHEMS), have published a press release.
2018-07-20
Press Release

Spatial Distribution of the Milky Way Hot Gaseous Halo Constrained by Suzaku X-Ray Observations

The research team, including Yoshiyuki Inoue (Senior Research Scientist, iTHEMS), have published a press release.
2018-06-22
Press Release

Modeling the functions of condensin in chromosome shaping and segregation

Former iTHES fellow, Yuji Sakai (Univ. Tokyo) together with Atsushi Mochizuki (iTHEMS), Masashi Tachikawa (iTHEMS), Tetsuya Hirano (RIKEN) and Kazuhisa Kinoshita (RIKEN) have published a paper and a press release. Immediately before a cell divides, chromosomal DNA in a eukaryotic cell is packaged into a discrete set of rod-shaped chromosomes. This process, known as mitotic chromosome assembly or condensation, secures the faithful segregation of genetic information into daughter cells. Central to this mechanistically complex process is a class of protein complexes known as condensins. However, how condensins support the assembly and segregation of mitotic chromosomes at a mechanistic level remains elusive. Here we construct a coarse-grained physical model of chromosomal DNA fibers and condensin molecules, and study how condensins work in the mitotic chromosome assembly using computer simulations. Our results show that two activities of condensins, formation of consecutive loops in chromosomal DNA fibers and inter-condensin attractions, are necessary for both the shaping and segregation of mitotic chromosomes, and balancing acts of these activities help to coordinate the efficient progress of the processes. Importantly, chromosome shaping and segregation in our results are strongly correlated, implying that they are controlled by the same underlying mechanism mediated by condensins.
2018-06-05
Press Release

Neutron Life from Supercomputer Simulations

Jason Chang (iTHEMS/LBNL) and his colleagues have enlisted powerful supercomputers to calculate a quantity known as the "nucleon axial coupling," – which is central to our understanding of a neutron’s lifetime – with an unprecedented precision. Their method offers a clear path to further improvements that may help to resolve the experimental discrepancy of the lifetime of neutrons as well as to learn about as-yet undiscovered physics. The paper was published was published online May 30 in the journal Nature.
2018-05-24
Press Release

Using the K computer, scientists predict exotic “di-Omega” particle

Based on complex simulations of quantum chromodynamics performed using the K computer, one of the most powerful computers in the world, the HAL QCD Collaboration, made up of scientists from the RIKEN Nishina Center for Accelerator-based Science and the RIKEN Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) program, together with colleagues from a number of universities, have predicted a new type of “dibaryon”—a particle that contains six quarks instead of the usual three. Studying how these elements form could help scientists understand the interactions among elementary particles in extreme environments such as the interiors of neutron stars or the early universe moments after the Big Bang.

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