Colloquium
72 events
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ColloquiumEfficient iBF: Balanced Integration of Fragmented Matching Markets for Welfare Improvement
September 4 (Fri) 15:30 - 17:00, 2026
Fuhito Kojima (Professor, Department of Economics, The University of Tokyo)
Matching markets often suffer from fragmentation, which leads to inefficiency. We model a fragmented market in a school-choice context and offer a practically relevant method for integration. Specifically, each student and school belong to a region, and we allow for inter-regional transfer of students with "balancedness" constraint: a matching is said to be balanced if, for each region, the outflow of students from that region to other regions is equal to the inflow of students from the latter to the former. Using a directed bipartite graph defined on students and schools, we characterize the set of Pareto efficient matchings among those that are individually rational, balanced and fair (efficient iBF). We also provide a class of polynomial-time algorithms to compute such matchings. When each region favors local students in their priority, the outcome of an algorithm from this class weakly improves student welfare upon the outcome where each region independently uses the deferred acceptance mechanism. Various real-life examples of fragmentation are discussed, and we illustrate how our method would address the issue.
Venue: Okochi Hall (Main Venue) / via Zoom
Event Official Language: English
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ColloquiumHidden Networks: From Phase Reductions to Effective Network Interactions
August 24 (Mon) 15:30 - 17:00, 2026
Christian Bick (Associate Professor, Department of Mathematics, Vrije Universiteit Amsterdam, Netherlands)
From networks of interconnected neurons in the brain to coupled electrochemical reactions: The collective dynamics of interacting dynamical systems shape the function (or dysfunction) of many systems that are critical for our everyday lives. For coupled oscillatory processes, synchronization is a prime example of emergent collective dynamics. But how oscillators interact is not necessarily obvious from (physical) connections between the oscillators. Here we look at phase reductions as a way to uncover the hidden 'effective' network interactions for coupled oscillators dynamics. On the one hand, these give insight into when oscillators do and do not interact (despite a link). On the other hand, they elucidate when and how nonpairwise higher-order interactions shape synchronization phenomena in coupled oscillator networks.
Venue: Okochi Hall (Main Venue) / via Zoom
Event Official Language: English
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ColloquiumThe 33th MACS Colloquium
July 17 (Fri) 14:45 - 18:00, 2026
Hajime Naruse (Professor, Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University)
Yohsuke Murase (Team Director, Mathematical Social Science Team, Division of Applied Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))14:45-15:00 Teatime Discussion 15:00-16:00 Hajime Naruse (Professor, Department of Geophysics, Graduate School of Science, Kyoto University) "What Do Sedimentary Layers Remember? Exploring Past Earth Environments through Machine Learning" 16:15-17:15 Yosuke Murase (Team Director, Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), RIKEN) "Mathematics of Cooperation in Society: The Evolution of Cooperation through Direct and Indirect Reciprocity" 17:15-18:00 Discussion
Venue: Science Seminar House (Map 9), Kyoto University
Event Official Language: Japanese
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ColloquiumHow did we come to be? — Particle Physics for the Next Decades —
July 10 (Fri) 15:30 - 17:00, 2026
Hitoshi Murayama (Professor, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The University of Tokyo / Professor, Department of Physics, University of California, Berkeley, USA)
Particle Physics is a study of the smallest and the biggest to uncover the fundamental laws that govern the universe. In recent years, both the United States and Europe have been through long-range planning processes. The future plans worldwide include the studies of (1) neutrinos that may have saved us from a complete annihilation, (2) the Higgs boson that keeps us in one piece, (3) dark matter that assembled us from the primordial soup, (4) inflation that created the macroscopic universe, and (5) the exploration of unknown particles and forces. It requires development of mind-boggling technologies.
Venue: Okochi Hall (Main Venue) / via Zoom
Event Official Language: English
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Colloquium
The 32th MACS Colloquium
April 17 (Fri) 14:45 - 18:30, 2026
Natsuki Tomida (Associate Professor, Center for Science Adventure and Collaborative Research Advancement (SACRA), Graduate School of Science, Kyoto University)
14:45-15:00 Tea Time Discussion 15:00-16:00 Natsuki Tomida (Associate Professor, Center for Science Adventure and Collaborative Research Advancement (SACRA), Graduate School of Science, Kyoto University) "Exploring the Origin of Mass" 16:15-17:20 2026 Study Group introduction session 17:30-18:30 Discussion
Venue: Science Seminar House (Map 9), Kyoto University
Event Official Language: Japanese
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Colloquium
The 31th MACS Colloquium & 2025 MACS Achievement Report Meeting
February 18 (Wed) 14:45 - 18:00, 2026
Yujiro Eto (Associate Professor, Center for Science Adventure and Collaborative Research Advancement (SACRA), Graduate School of Science, Kyoto University)
14:45-15:00 Teatime discussion [15:00-16:00 The 31th MACS Colloquium] Talk by Dr. Yujiro Eto (Associate Professor, Center for Science Adventure and Collaborative Research Advancement (SACRA), Graduate School of Science, Kyoto University) [16:10-18:30 2025 MACS Achievement Report Meeting] 16:10-17:10 Flash Talks to report results 17:10-18:00 Poster Session by SG participating students
Venue: ＃401, Graduate School of Science Bldg. No.6 , Kyoto University
Event Official Language: Japanese
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Colloquium
Measuring evolutionary forces of cultural change
January 13 (Tue) 14:00 - 15:30, 2026
Joshua B. Plotkin (Walter H. and Leonore C. Annenberg Professor of the Natural Sciences, University of Pennsylvania, USA)
I will describe how to measure the forces that drive cultural change, using inference tools from evolutionary theory. We study time series data from large corpora of parsed English texts to identify what drives language change over the course of centuries. We also measure frequency-dependent effects in time series of baby names and purebred dog preferences. The form of frequency dependence we infer helps to explain the diversity distribution of names, and it replicates across the United States, France, Norway and the Netherlands. We find different growth laws for male versus female names, attributable to different rates of innovation, whereas names from the bible enjoy a genuine advantage at all frequencies. Frequency dependence emerges from a host of underlying social and cultural mechanisms, including a preference for novelty that recapitulates fashion trends in dog owners. Studying culture through the lens of evolutionary theory provides a quantitative account of social pressures to conform or to be different; and it provides inference tools that may be used in biology as genetic and phenotypic time series are increasingly available.
Venue: Okochi Hall (Main Venue) / via Zoom
Event Official Language: English
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Colloquium
The 30th MACS Colloquium
November 28 (Fri) 14:45 - 18:00, 2025
Isao Ishikawa (Program-Specific Associate Professor, Center for Science Adventure and Collaborative Research Advancement (SACRA), Graduate School of Science, Kyoto University)
Ken-ichi Kurotani (Associate Professor, Center for Science Adventure and Collaborative Research Advancement (SACRA), Graduate School of Science, Kyoto University)14:45-15:00 Teatime discussion 15:00–16:00 Talk by Dr. Isao Ishikawa (Program-Specific Associate Professor, Center for Science Adventure and Collaborative Research Advancement (SACRA), Graduate School of Science, Kyoto University) 16:15–17:15 Talk by Dr. Ken-ichi Kurotani (Associate Professor, Center for Science Adventure and Collaborative Research Advancement (SACRA), Graduate School of Science, Kyoto University) 17:15-18:00 Discussion
Venue: Science Seminar House (Map 9), Kyoto University
Event Official Language: Japanese
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Colloquium
Why do we sleep? — The Role of Calcium and Phosphorylation in Sleep
October 10 (Fri) 15:30 - 17:00, 2025
Hiroki R. Ueda (Professor, Systems Pharmacology, Graduate School of Medicine, The University of Tokyo / Professor, Department of Systems Biology, Institute of Life Science, Kurume University)
Sleep remains one of greatest remaining mysteries. At the Sleep 2012 conference, we conceived a shift from the concept of “sleep substances” to “wake substances” such as calcium, suggesting that sleep homeostasis may arise from the integration of wake-related activity. Inspired by Dr. Setsuro Ebashi’s work on calcium signaling, we investigated calcium’s role in sleep regulation. Using our Triple-CRISPR method (Sunagawa et al. 2016), we screened 25 genes related to calcium channels and pumps, revealing calcium as a brake on brain activity to promote sleep (Tatsuki et al. 2016). We also developed a tissue-clearing method CUBIC (Susaki et al. 2014; Tainaka et al. 2014) to visualize calcium’s effects on neural circuits. Further work showed that calcium-dependent enzymes, CaMKIIα/β kinases, act as calcium “memory” devices, with phosphorylation sites controlling sleep onset, duration, and termination (Tone et al. 2022). Other direct and indirect calcium-dependent phosphatases, Calcineurin and PP1 (sleep-promoting), and opposing kinases, PKA (wake-promoting), function as synaptic sleep switches (Wang et al. 2024). We also identified the ryanodine receptor 1, a calcium channel, as a molecular target of inhalational anesthetics, hinting at shared pathways between anesthesia and sleep (Kanaya et al. 2025). Lastly, we proposed the WISE (Wake Inhibition Sleep Enhancement) mechanism, where quiet wakefulness suppresses and deep sleep strengthens synaptic connections, explaining links between sleep, depression, and antidepressant effects (Kinoshita et al. 2025).
Venue: Okochi Hall (Main Venue) / via Zoom
Event Official Language: English
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Colloquium
Chemical and isotopic analyses of samples returned by the Hayabusa2 mission from the asteroid Ryugu
August 1 (Fri) 14:00 - 15:30, 2025
Tetsuya Yokoyama (Professor, Department of Earth and Planetary Sciences, School of Science, Institute of Science Tokyo)
The recent success of asteroid sample return missions has led to significant advances in Solar System science. JAXA's Hayabusa2 successfully retrieved and returned to Earth a total of 5.4 grams of samples from the C-type asteroid Ryugu. Sample return missions are critical to the scientific community, as they provide pristine, terrestrially unaltered extraterrestrial material. The analytical data obtained in laboratories for samples collected by space missions will facilitate the understanding of the formation and evolution of the Solar System. I was appointed deputy leader of the Initial Analysis Chemistry team of Hayabusa2 project, and was heavily involved in analyzing the chemical and isotopic compositions of Ryugu materials. A series of analyses of these samples indicated that the mineral, chemical, and isotopic compositions of Ryugu bear a strong resemblance to those of the Ivuna-type (CI) carbonaceous chondrites. CI chondrites have been recognized as a unique group of meteorites with a chemical composition similar to that of the solar photosphere except for highly volatile elements and Li. In the seminar, I will present the meaning and significance of the compositional similarity between Ryugu and CI chondrites. I will also present our recent activities in a new project called the Ryugu Reference Project, which was initiated to maximize the potential value of the returned samples.
Venue: 2F Large Conference Room, Administrative Headquarters, RIKEN Wako Campus (Main Venue) / via Zoom
Event Official Language: English
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Colloquium
The 29th MACS Colloquium
July 4 (Fri) 14:45 - 18:00, 2025
Takashi Sakajo (Professor, Division of Mathematics and Mathematical Sciences, Graduate School of Science, Kyoto University)
Shinichi Sasa (Professor, Division of Physics and Astronomy, Graduate School of Science, Kyoto University)14:45-15:00 Teatime discussion 15:00–15:50 Talk by Prof. Takashi Sakajo (Professor, Division of Mathematics and Mathematical Sciences, Graduate School of Science, Kyoto University) 16:00–16:50 Talk by Prof. Shinichi Sasa (Professor, Division of Physics and Astronomy, Graduate School of Science, Kyoto University) 17:15-18:00 Discussion
Venue: Science Seminar House (Map 9), Kyoto University
Event Official Language: Japanese
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Colloquium
The 28th MACS Colloquium
April 25 (Fri) 14:45 - 18:30, 2025
Shizuo Kaji (Professor, Institute of Mathematics for Industry, Kyushu University / Professor, Center for Science Adventure and Collaborative Research Advancement (SACRA), Graduate School of Science, Kyoto University)
14:45-15:00 Teatime discussion 15:00-16:00 Talk by Prof. Shizuo Kaji (Professor, Institute of Mathematics for Industry, Kyushu University / Professor, Center for Science Adventure and Collaborative Research Advancement (SACRA), Graduate School of Science, Kyoto University) 16:15-17:20 2024 Study Group introduction session 17:30-18:30 Discussion
Venue: Science Seminar House (Map 9), Kyoto University
Event Official Language: Japanese
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Colloquium
Smart heuristics of a single-celled organism
March 7 (Fri) 14:00 - 15:30, 2025
Toshiyuki Nakagaki (Professor, Research Institute for Electronic Science, Hokkaido University)
Although we rarely question how smart unicellular organisms are, it has become clear that unicellular organisms are smarter than we expected. In fact, various protozoa (unicellular eukaryotes) can take actions that are advantageous for their survival even in complex environments in the wild environments. In this talk, I will introduce some typical examples of smart behaviors in a protozoan amoeba (the plasmodium of Physarum polycephalum): (1) maze-solving, (2) formation of multi-functional transport network that mimics public transportation network among cities in Tokyo region, and so on. We will propose a mathematical model of these behaviors and extract the heuristics (simple rules of behavior) that give rise to their smartness. In general, we will discuss the future potential of research into the behavioral intelligence of protozoa.
Venue: Okochi Hall (Main Venue) / via Zoom
Event Official Language: English
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Colloquium
MACS 10th Anniversary Colloquium & 2024 MACS Achievement Report Meeting
February 19 (Wed) 14:45 - 18:30, 2025
Hiroshi Kokubu (Executive Vice-President, Kyoto University)
Yoshiko Takahashi (Professor, Division of Biological Sciences, Graduate School of Science, Kyoto University)14:45-15:00 Teatime discussion [15:00-16:30 First part: MACS 10th Anniversary Colloquium] 15:05-15:05 Opening 15:05-15:30 Talk by Prof. Hiroshi KOKUBU Title: How did MACS begin? Abstract: As the MACS program, which began with a kick-off symposium in May 2016, enters its 10th year in the academic year 2025, I would like to look it back and talk about how it started, what thoughts shared by people involved at the time led to the spirit of MACS. I’d also like to share ideas and experiences in the history of MACS over the past 10 years, including what we wanted to do with MACS in the beginning but could not, or how MACS have collaborated with other subsequent activities of Kyodai RIGAKU (Kyoto U Science). 15:30-15:55 Talk by Prof. Yoshiko TAKAHASHI Title: Excitement through the MACS program Abstract: When the MACS program was launched, a research article was published by Harvard University, in which the gut looping during vertebrate development was beautifully explained by inter-disciplined science with experimental biology, physics, and mathematics. I was very impressed and motivated by this paper, and aimed at similar new waves through the MACS program. I have been running a study group, in which graduate- and undergrad students of not only life science but also physics and mathematics joined, and we enjoyed discussion and looking at real chicken embryos. Such experiences are not what we can easily obtain in conventional education program in campus life. 15:55-16:20 Discussion 16:20-16:30 Break [16:30-18:30 Second part: 2024 MACS Achievement Report Meeting] 16:30-17:30 Flash Talks to report results 17:30-18:30 Poster Session by SG participating students
Venue: Science Seminar House (Map 9), Kyoto University
Event Official Language: Japanese
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Colloquium
The 27th MACS Colloquium
November 25 (Mon) 14:45 - 18:00, 2024
Ryusuke Hamazaki (RIKEN Hakubi Team Leader, Nonequilibrium Quantum Statistical Mechanics RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research (CPR))
Teruaki Enoto (Associate Professor, Department of Physics, Division of Physics and Astronomy, Graduate School of Science, Kyoto University)14:45-15:00 Teatime discussion 15:00-16:00 Talk by Dr. Ryusuke Hamazaki (RIKEN Hakubi Team Leader, Nonequilibrium Quantum Statistical Mechanics RIKEN Hakubi Research Team) 16:15-17:15 Talk by Dr. Teruaki Enoto (Associate Professor, Department of Physics, Division of Physics and Astronomy, Graduate School of Science, Kyoto University) 17:15-18:00 Discussion
Venue: Maskawa Hall, 1F, Maskawa Building for Education and Research
Event Official Language: Japanese
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Colloquium
The 26th MACS Colloquium
July 8 (Mon) 14:45 - 18:00, 2024
Satoshi Taguchi (Professor, Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University)
Michitaka Notaguchi (Professor, Division of Biological Sciences, Graduate School of Science, Kyoto University)14:45-15:00 Teatime discussion 15:00-16:00 Talk by Prof. Satoshi Taguchi (Professor, Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University) 16:15-17:15 Talk by Prof. Yoshihiro Morishita (Professor, Division of Biological Sciences, Graduate School of Science, Kyoto University) 17:15-18:00 Discussion
Venue: Science Seminar House (Map 9), Kyoto University
Event Official Language: Japanese
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Colloquium
The New World of Spin Zero - Some Novel Approaches at QUP for Experimental Particle Cosmology -
May 28 (Tue) 13:30 - 15:00, 2024
Masashi Hazumi (Director, Professor, International Center for Quantum-field Measurement Systems for Studies of the Universe and Particles (QUP), High Energy Accelerator Research Organization (KEK))
Particle cosmology is a discipline seeking a fundamental understanding of the Universe based on particle physics. Five mysteries drive our research today: cosmic inflation, baryon asymmetry, neutrino properties, dark matter, and dark energy. Resolving any of the five mysteries will revolutionize our picture of the Universe. Numerous interesting theoretical hypotheses have been proposed to this end. Many require new scalar quantum fields, such as inflatons, axions, supersymmetric particles, etc. They are, in a sense, an attempt to expand the role of the vacuum. Since we have not found such spin-zero fields yet, we shall invent new eyes to make an experimental or observational breakthrough. The International Center for Quantum-field Measurement Systems for Studies of the Universe and Particles (QUP) was established in December 2021 at KEK under the WPI program of MEXT and JSPS. With its tagline of "bring new eyes to humanity," one of the primary missions of QUP is inventing and developing such new eyes for particle cosmology. In this seminar, after briefly introducing QUP, I focus on research topics I have contributed, including the LiteBIRD satellite to study inflatons and light scalar quantum field searches with novel methods using quantum sensing techniques.
Venue: Okochi Hall / via Zoom
Event Official Language: English
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Colloquium
The 25th MACS Colloquium
April 19 (Fri) 14:45 - 18:30, 2024
Wataru Morita (Researcher, Department of Anthropology, National Museum of Nature and Science / Associate Professor, Department of Biological Sciences, Graduate School of Science, The University of Tokyo)
14:45-15:00 Teatime discussion 15:00-16:00 Talk by Dr. Wataru Morita (Researcher, Department of Anthropology, National Museum of Nature and Science / Associate Professor, Department of Biological Sciences, Graduate School of Science, The University of Tokyo) 16:15-17:20 2024 Study Group introduction session 17:30-18:30 Discussion
Venue: Maskawa Hall, 1F, Maskawa Building for Education and Research
Event Official Language: Japanese
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Colloquium
Bridging physics and society: A case study of collective memory dynamics by socio-econophysics approach
November 20 (Mon) 15:00 - 16:30, 2023
Yukie Sano (Associate Professor, Institute of Systems and Information Engineering, University of Tsukuba)
The movements of individuals with free will are unpredictable, complex, and, needless to say, fundamentally distinct from the movements of matter. Furthermore, studying society, which forms collectives while engaging in intricate individual interactions, using mathematical models seems incredibly daunting. However, when analyzing empirical data, relatively simple mathematics often emerge in the distribution and dynamics of society at the level of collective behavior. Additionally, such mathematics often share commonalities with physical phenomena. With this background, research is progressing by applying ideas from physics to social-economic phenomena, a field known as socio-econophysics. In this presentation, I will introduce a mathematical model that addresses the decay of collective memory using access logs on the web as an example of research in socio-econophysics.
Venue: Okochi Hall / via Zoom
Event Official Language: English
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Colloquium
The 24th MACS Colloquium
November 20 (Mon) 14:45 - 18:00, 2023
Satoshi Horike (Professor, Department of Chemistry, Graduate School of Science, Kyoto University)
Yoshihiro Morishita (Team Leader, Laboratory for Developmental Morphogeometry, RIKEN Center for Biosystems Dynamics Research (BDR))14:45-15:00 Teatime discussion 15:00-16:00 Talk by Dr. Satoshi Horike (Professor, Department of Chemistry, Graduate School of Science, Kyoto University) Title: Material science of new glasses of metal-molecular architectures Abstract: The three major materials - ceramics, metals and organic polymers - all form glass phases and underpin our daily lives and industry. Unlike crystals, glasses have a random structure and designing their molecular structures and properties is still a major challenge. In this talk, I will present research on new glasses made of metals and molecules. It will discuss how the glasses are designed and synthesised, as well as the unique glass structures and functions that result from the metal-molecule chemical bonds. 16:15-17:15 Talk by Prof. Yoshihiro Morishita (RIKEN Center for Biosystems Dynamics Research, Team leader) Title: Optimal coding design of positional information and an appropriate spacetime coordinate system to capture an archetype of organ morphogenetic dynamics Abstract: We are engaged in developmental biology research at the intersection of experimentation and theory, driven by a curiosity to understand the laws governing organogenesis. Ideally, we aim to mathematically represent these laws and find commonalities across species and organs. In this seminar, I will present research on a coding design of spatial information within developing tissues, as well as propose spacetime coordinates to directly and quantitatively compare the morphogenetic dynamics of homologous organs across species with different sizes and developmental rates. Furthermore, we will introduce results suggesting the existence of speceis-independent morphogenetic dynamics (a kind of archetype) achieved by applying these methods to biological data. 17:15-18:00 Discussion
Venue: Maskawa Hall, 1F, Maskawa Building for Education and Research
Event Official Language: Japanese
72 events