iTHEMSコロキウム
35 イベント
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コロキウムEfficient iBF: Balanced Integration of Fragmented Matching Markets for Welfare Improvement
2026年9月4日(金) 15:30 - 17:00
小島 武仁 (東京大学 経済学研究科 教授)
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.
会場: 大河内記念ホール (メイン会場) / via Zoom
イベント公式言語: 英語
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コロキウムHidden Networks: From Phase Reductions to Effective Network Interactions
2026年8月24日(月) 15:30 - 17:00
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.
会場: 大河内記念ホール (メイン会場) / via Zoom
イベント公式言語: 英語
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コロキウムHow did we come to be? — Particle Physics for the Next Decades —
2026年7月10日(金) 15:30 - 17:00
村山 斉 (東京大学 カブリ数物連携宇宙研究機構 (Kavli IPMU) 教授 / 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.
会場: 大河内記念ホール (メイン会場) / via Zoom
イベント公式言語: 英語
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コロキウム
Measuring evolutionary forces of cultural change
2026年1月13日(火) 14:00 - 15:30
ジョシュア・プロトキン (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.
会場: 大河内記念ホール (メイン会場) / via Zoom
イベント公式言語: 英語
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コロキウム
Why do we sleep? — The Role of Calcium and Phosphorylation in Sleep
2025年10月10日(金) 15:30 - 17:00
上田 泰己 (東京大学 大学院医学系研究科 システムズ薬理学教室 教授 / 久留米大学 分子生命科学研究所 個体システム生物学研究部門 教授)
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).
会場: 大河内記念ホール (メイン会場) / via Zoom
イベント公式言語: 英語
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コロキウム
Chemical and isotopic analyses of samples returned by the Hayabusa2 mission from the asteroid Ryugu
2025年8月1日(金) 14:00 - 15:30
横山 哲也 (東京科学大学 理学院 地球惑星科学系 教授)
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.
会場: 理化学研究所和光キャンパス 本部棟2階大会議室 (メイン会場) / via Zoom
イベント公式言語: 英語
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コロキウム
Smart heuristics of a single-celled organism
2025年3月7日(金) 14:00 - 15:30
中垣 俊之 (北海道大学 電子科学研究所 教授)
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.
会場: 大河内記念ホール (メイン会場) / via Zoom
イベント公式言語: 英語
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コロキウム
The New World of Spin Zero - Some Novel Approaches at QUP for Experimental Particle Cosmology -
2024年5月28日(火) 13:30 - 15:00
羽澄 昌史 (高エネルギー加速器研究機構 (KEK) 量子場計測システム国際拠点(QUP) 拠点長)
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.
会場: 大河内記念ホール / via Zoom
イベント公式言語: 英語
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コロキウム
Bridging physics and society: A case study of collective memory dynamics by socio-econophysics approach
2023年11月20日(月) 15:00 - 16:30
佐野 幸恵 (筑波大学 システム情報系 准教授)
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.
会場: 大河内記念ホール / via Zoom
イベント公式言語: 英語
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コロキウム
The eyes have it: Influenza virus infection beyond the respiratory tract
2023年7月11日(火) 14:00 - 15:30
ジェシカ・ベルザ (Research Microbiologist, Influenza Division, US Centers for Disease Control and Prevention (CDC), USA)
Influenza viruses are typically considered a respiratory pathogen, but are nonetheless capable of causing ocular complications in infected individuals and establishing a respiratory infection following ocular exposure. While both human and zoonotic influenza A viruses can replicate in ocular tissue and use the eye as a portal of entry, many H7 subtype viruses possess an ocular tropism in humans, though the molecular determinants that confer a non-respiratory tropism to a respiratory virus are poorly understood. In this presentation, I will discuss the establishment of several mammalian models to study ocular exposure and ocular tropism, ongoing investigations conducted in vitro and in vivo to elucidate properties associated with ocular-tropic viruses, and ways in which this information can improve efforts to identify, treat, and prevent human infection following ocular exposure to influenza viruses. Continued investigation of the capacity for respiratory viruses to gain entry to the respiratory tract and to cause ocular complications will improve understanding of how these pathogens cause human disease, regardless of the virus subtype or exposure route.
会場: 大河内記念ホール / via Zoom
イベント公式言語: 英語
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コロキウム
Emergence of Extreme Universe from Quantum Information
2023年4月17日(月) 16:00 - 17:30
高柳 匡 (京都大学 基礎物理学研究所 教授)
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.
会場: via Zoom
イベント公式言語: 英語
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コロキウム
Scaling Optimal Transport for High dimensional Learning
2023年1月24日(火) 17:00 - 18:30
Gabriel Peyré (Research Director, CNRS/École Normale Supérieure, France)
iTHEMS-AIP Joint Colloquium Optimal transport (OT) has recently gained a lot of interest in machine learning. It is a natural tool to compare in a geometrically faithful way probability distributions. It finds applications in both supervised learning (using geometric loss functions) and unsupervised learning (to perform generative model fitting). OT is however plagued by the curse of dimensionality, since it might require a number of samples which grows exponentially with the dimension. In this talk, I will explain how to leverage entropic regularization methods to define computationally efficient loss functions, approximating OT with a better sample complexity. More information and references can be found on the website of our book "Computational Optimal Transport" (see related link below).
会場: via Zoom
イベント公式言語: 英語
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コロキウム
The Epidemiology and Economics of Physical Distancing during Infectious Disease Outbreaks
2022年12月14日(水) 11:00 - 12:30
Troy Day (Professor, Head of Department, Department of Mathematics and Statistics, Queen's University, Canada)
People's incentives during an infectious disease outbreak influence their behaviour, and this behaviour can impact how the outbreak unfolds. Early on during an outbreak, people are at little personal risk of infection and hence may be unwilling to change their lifestyle to slow the spread of disease. As the number of cases grows, however, people may then voluntarily take extreme measures to limit their exposure. Political leaders also respond to the welfare and changing desires of their constituents, through public health policies that themselves shape the course of the epidemic and its ultimate health and economic repercussions. In this talk I will use ideas from the study of differential games to model how individuals’ and politicians’ incentives change during an outbreak, and the epidemiological and economic consequences that ensue when these incentives are acted upon. Motivated by the COVID-19 pandemic, I focus on physical distancing behaviour and the imposition of stay-at-home orders by politicians. I show that there is a fundamental difference in the political, economic, and health consequences of an infectious disease outbreak depending on the degree of asymptomatic transmission. If transmission occurs primarily by asymptomatic carriers, then politicians will be incentivized to impose stay-at-home orders earlier and for longer than individuals would like. Despite such orders being unpopular, however, they ultimately benefit all individuals. On the other hand, if the disease is transmitted primarily by symptomatic infections, then individuals are incentivized to stay at home earlier and for longer than politicians would like. In this case, politicians will be incentivized to impose back-to-work orders that, despite being unpopular, will again ultimately be to the benefit of all individuals. This is joint work with David McAdams, Fuqua School of Business and Economics Department, Duke University.
会場: via Zoom
イベント公式言語: 英語
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コロキウム
From the Black Hole Conundrum to the Structure of Quantum Gravity
2022年7月26日(火) 15:30 - 17:00
野村 泰紀 (Professor/Director, Berkeley Center for Theoretical Physics, University of California, Berkeley, USA)
Having a complete quantum theory of gravity has long been a major goal of theoretical physics. This is because a naive merger of quantum mechanics and general relativity — though it works in certain limited regimes — suffers from major theoretical problems. A particularly acute one arises when one considers the quantum mechanics of black holes: two fundamental principles of modern physics — the conservation of probability in quantum mechanics and the equivalence principle of general relativity — seem to be incompatible with each other. I will explain how recent theoretical progress begins to address this problem and portray the emerging picture of how spacetime and gravity behave at the level of full quantum gravity.
会場: 理化学研究所 和光キャンパス RIBF棟 2階 大会議室 / via Zoom
イベント公式言語: 英語
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コロキウム
How is turbulence born: Statistical mechanics and ecological collapse in transitional fluids
2022年4月22日(金) 15:00 - 16:30
Hong-Yan Shih (Assistant Research Fellow, Institute of Physics, Academia Sinica, Taiwan)
The onset of turbulence is ubiquitous in daily life and is important in various industrial applications, yet how fluids become turbulent has remained unsolved for more than a century. Recent experiments in pipe flow finally quantified this transition, showing that non-trivial statistics and spatiotemporal complexity develop as the flow velocity is increased. Combining numerical simulations of the hydrodynamics equations and an effective theory from statistical mechanics, we discovered the surprising fact that fluid behavior at the transition is governed by the emergent predator-prey dynamics, leading to the mathematical prediction that the laminar-turbulent transition is analogous to an ecosystem on the edge of extinction. This prediction demonstrates that the laminar-turbulent transition is a non-equilibrium phase transition in the directed percolation universality class, and provides a unified picture of transition to turbulence in various systems. I will also show our recent progresses on transitional turbulence, including how an extended ecological model with energy balance successfully recapitulates the spatiotemporal patterns beyond the critical point, and the determination of the critical behavior and an emergent novel phase under interactions in the experimental collaboration.
会場: via Zoom
イベント公式言語: 英語
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コロキウム
High-Energy Neutrino Astrophysics in the Multimessenger Era
2021年10月28日(木) 15:00 - 16:30
村瀬 孔大 (Associate Professor, Pennsylvania State University, USA)
The discovery of high-energy cosmic neutrinos opened a new window of astroparticle physics. Their origin is a new mystery in the field, which is tightly connected to the long-standing puzzle about the origin of cosmic rays. I will give an overview of the latest results on high-energy neutrino and cosmic-ray observations, and demonstrate the power of "multimessenger" approaches. In particular, I will show that the observed fluxes of neutrinos, gamma rays, and extragalactic cosmic rays can be understood in a unified manner. I will also highlight the recent developments about astrophysical neutrino emission from supermassive black holes and violent transient phenomena. Possibilities of utilizing high-energy neutrinos as a probe of heavy dark matter may be discussed.
会場: via Zoom
イベント公式言語: 英語
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コロキウム
Finding Gravitational Waves from the Early Universe
2021年9月27日(月) 16:00 - 17:30
小松 英一郎 (Director, Max Planck Institute for Astrophysics, Germany)
The Cosmic Microwave Background (CMB) gives a photographic image of the Universe when it was still an “infant”. We have been using it to test our ideas about the origin of the Universe. The CMB research told us a remarkable story: the structure we see in our Universe such as galaxies, stars, planets, and eventually ourselves originated from tiny quantum fluctuations in the period of the early Universe called cosmic inflation. While we have accumulated strong evidence for this picture, the extraordinary claim requires extraordinary evidence. The last prediction of inflation that is yet to be confirmed is the existence of primordial gravitational waves whose wavelength can be as big as billions of light years. To this end we have proposed to JAXA a new satellite mission called LiteBIRD, whose primary scientific goal is to find signatures of gravitational waves in the polarisation of the CMB. In this presentation we describe physics of gravitational waves from inflation, and the LiteBIRD proposal.
会場: via Zoom
イベント公式言語: 英語
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コロキウム
Quantitative Population Dynamics in Interdisciplinary Biology
2021年7月8日(木) 10:30 - 12:00
岩見 真吾 (名古屋大学 大学院理学研究科 教授)
Through the course of life, from the moment of birth till death, an organism will achieve various states of equilibrium or ‘homeostasis’ which will inevitably encounter perturbations. The processes of cell growth, differentiation, infection, mutation, evolution and adaptation work together as a coordinated ‘system’, described by mathematical models for population dynamics, to maintain a healthy state. Any disruptions to this system leads to disease including infection, allergy, cancer, and aging. We are conducting interdisciplinary research to elucidate “Quantitative Population Dynamics” through the course of life with original mathematical theory and computational simulation, which are both our CORE approach. Our mathematical model-based approach has quantitatively improved a current gold-standard approach essentially relying on the statistical analysis of “snapshot data” during dynamic interaction processes in life sciences research. In this talk, I will explain how our interdisciplinary approach extends our understanding for complicated clinical data and apply real world problem with an example of the Novel Coronavirus Disease, COVID-19.
会場: via Zoom
イベント公式言語: 英語
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コロキウム
Mirror symmetry and KAM theory
2021年4月16日(金) 13:30 - 15:00
深谷 賢治 (Permanent Member, Simons Center for Geometry and Physics, Stony Brook University, New York, USA)
13:30pm-15:00pm (JST) Mirror symmetry is a phenomenon discovered in String theory and is much discussed recently in mathematics especially in the field of complex (algebraic) geometry and symplectic geometry. Strominger-Yau-Zaslow found that this phenomenon is closed related to a Lagrangian torus fibration. In an integrable system in Hamiltonian dynamics, the phase space is foliated by Lagrangian tori. I would like to explain a program that the Lagrangian torus fibration found by Strominger-Yau-Zaslow could be regarded as one appearing certain integrable system and KAM theory (which describes a amiltonian dynamics that is a perturbation of an integrable system) could appear in the situation of Mirror symmetry.
会場: via Zoom
イベント公式言語: 英語
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コロキウム
Geometry (形); Inconspicuous regulator that determines the fate of cells
2020年12月14日(月) 10:00 - 11:30
Sungrim Seirin-Lee (広島大学 教授)
December 14 at 10:00-11:30, 2020 (JST) December 13 at 20:00-21:30, 2020 (EST) In the history of mathematical study in pattern formation, the effect of domain has been considered as an important factor that can regulate spatial patterning. However, it is still unknown in biology how the geometry of the domain such as nuclear or cellular shapes can directly regulate the cell fate. In this talk, I will introduce two studies of spatial reorganization in chromatin and cellular dynamics and show that the domain is likely to play a critical role in determining the cell function.
会場: via Zoom
イベント公式言語: 英語
35 イベント