セミナー
646 イベント

セミナー
Boundaryinduced transitions in Möbius quenches of holographic BCFT
2024年5月15日(水) 16:00  17:30
Dongsheng Ge (大阪大学 大学院理学研究科 特任研究員)
Boundary effects play an interesting role in finitesize physical systems. In this work, we study the boundaryinduced properties of 1+1dimensional critical systems driven by inhomogeneous Möbiuslike quenches. We focus on the entanglement entropy in BCFTs with a large central charge and a sparse spectrum of lowdimensional operators. We find that the choice of boundary conditions leads to different scenarios of dynamical phase transitions. We also derive these results in a holographic description in terms of intersecting branes in AdS3, and find a precise match.
会場: セミナー室 (359号室) (メイン会場) / via Zoom
イベント公式言語: 英語

セミナー
Quantum Computing in Omics Medicine
2024年5月10日(金) 16:00  17:15
角田 達彦 (東京大学 大学院理学系研究科 生物科学専攻 教授)
(The speaker is also the team leader of Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences. This is a joint seminar with the iTHEMS Biology Group.) In medical science, the recent explosive development of omics technologies has enabled the measurement not only of bulk data from entire tissues, but also data for individual cells and their spatial location information, and even allowed collection of such information in realtime. Meaningful interpretation of these rich data requires an ability to understand highorder and complex relationships that underpin biological phenomena such as drug response, simulating their dynamics, and selecting the optimal treatment for each patient based on these results. While these data are largescale and of ultrahigh dimensionality, they are also often sparse, with many missing values in the measurements and frequent higherorder interactions among variables, making them hard to handle with conventional statistics. To make further progress, machine learning – especially deep learning – is emerging as one of the promising ways forward. We have developed a method to transform omics data into an imagelike representation for analysis with deep learning (DeepInsight) and have successfully used it to predict drug response and to identify original cell types from singlecell RNAseq data. However, anticipation of the vast amount of medical data being accumulated gives particular urgency to addressing the problems of the time it actually takes to train deep learning models and the complexity of the necessary computational solutions. One possible way to resolve many of these problems is “quantum transcendence”, which is made possible by quantum superposition computation. Among all the different ways to apply quantum computation to medical science, we are particularly interested in quantum deep learning based on optimization and search problems, quantum modeling of single nucleotide detection by observational systems and statistical techniques such as regression analysis by inverse matrix computation and eigenvalue computation. In this seminar, I will first present an overview of how quantum machine learning and quantum deep learning can be used to formulate treatment strategies in medicine. We will discuss how to implement the quantum DeepInsight method, the challenges of noise in quantum computation when training QCNNs, feature mapping issues, problems of pretraining in quantum deep learning, and concerns relating to handling sensitive data such as genomic sequences. I hope this seminar will enhance our understanding of how to effectively facilitate medical research with quantum computing.
会場: セミナー室 (359号室) (メイン会場) / via Zoom
イベント公式言語: 英語

セミナー
Surrogate Modeling for Supernova Feedback toward StarbyStar Simulations of MilkyWaysized Galaxies
2024年5月10日(金) 14:00  15:15
Keiya Hirashima (東京大学 大学院理学系研究科 天文学専攻 博士課程)
Galaxy simulations have found the interdependence of multiscale gas physics, such as star formation, stellar feedback, inflow/outflow, and so on, by improving the physical models and resolution. The mass resolution remains capped at around 1,000 solar masses (e.g., Applebaum et al. 2021). To overcome the limitations, we are developing a new Nbody/SPH code, ASURAFDPS, to leverage exascale computing (e.g., Fugaku), handle approximately one billion particles, and simulate individual stars and stellar feedback within the galaxy. However, the emergence of communication costs hinders scalability beyond one thousand CPU cores. One of the causes is short timescale events localized in tiny regions, such as supernova explosions. In response, we have developed a surrogate model using machine learning to duplicate supernova feedback quickly (Hirashima et al., 2023a,b). In the presentation, I report the fidelity and progress of the simulations with our new machinelearning technique.
会場: セミナー室 (359号室) (メイン会場) / via Zoom
イベント公式言語: 英語

セミナー
Deep Learning for Estimating TwoBody Interactions in MixedSpecies Collective Motion
2024年5月9日(木) 16:00  17:00
上道 雅仁 (東京大学 大学院総合文化研究科 特任研究員)
(This is a joint seminar with the Information Theory Study Group.) Collective motion is a fundamental phenomenon observed in various biological systems, characterized by the coordinated movement of individual entities. Such dynamics are especially crucial in understanding cellular behaviors, which can now be observed at an individual level in complex tissue formations involving multiple types of cells, thanks to recent advancements in imaging technology. To harness this rich data and uncover the hidden mechanisms of such dynamics, we developed a deep learning framework that estimates equations of motion from observed trajectories. By integrating graph neural networks with neural differential equations, our framework effectively predicts the twobody interactions as a function of the states of the interacting entities. In this seminar, I will first introduce the structure and hyperparameters of our framework. Subsequently, I will detail two numerical experiments. The first is a simple toy model that was employed to generate data for testing our framework to refine the hyperparameters. The second explores a more complex scenario mimicking the collective motion of cellular slime molds, highlighting our model's ability to adapt to mixedspecies interactions.
会場: 研究本館 3階 359号室とZoomのハイブリッド開催
イベント公式言語: 英語

セミナー
Role of selfgravity on the central halo structure of fuzzy dark matter
2024年4月30日(火) 13:30  15:00
間仁田 侑典 (京都大学 基礎物理学研究所 協力研究員)
Fuzzy dark matter (FDM) is a dark matter model that is characterized by the ultralight masses around 10−22 eV. As FDM has the wavelike nature, the selfgravitating structure is described by the SchrödingerPoisson equation. Previous simulations based on the SchrödingerPoisson equation have demonstrated that solitonlike structure having a highdensity flat core is formed at the central region of the FDM halos, and the size of such a core is typically determined by the de Broglie wavelength. Away from the central core, the density profile of the FDM halos resembles that of the cold dark matter halos on average, and is shown to be described by the NavarroFrenkWhite (NFW) profile. In this paper, we study the role of the selfgravity of the soliton core, and its relation to the bulk halo properties by solving the SchrödingerPoisson equation in a simplified setup. The findings indicate that the contribution from the soliton selfgravity must dominate over the NFW potential in order to sustain the soliton.
会場: 研究本館 3階 359号室とZoomのハイブリッド開催
イベント公式言語: 英語

セミナー
How Stars End Their Lives
2024年4月26日(金) 14:00  15:15
Philipp Podsiadlowski (Professor, University of Oxford, UK)
While the basic evolution of stars has been understood for many decades, there are still major uncertainties in our overall understanding of how stars end their lives, both in the context of low and intermediatemass stars (including the Sun) and massive stars. I will first review some of key principles that govern the structure and evolution of stars and then present recent progress that has been made for both groups of stars. I will argue and present numerical simulations that show that all stars become dynamically unstable when they become large giant stars, which leads to sporadic, dynamical mass ejections. Low and intermediatemass stars may lose all of their envelopes as a consequence, leaving whitedwarf remnants. More massive stars experience core collapse, leaving a neutronstar or blackhole remnant, possibly associated with a supernova explosion. I will show how the dramatic recent progress on understanding the corecollapse process, for the first time, allows us to connect the late evolution of massive stars with the resulting supernova explosions and the final remnants and discuss how observations with current gravitationalwave detectors (such as LIGO) will allow us to test this theoretical connection.
会場: セミナー室 (359号室) (メイン会場) / via Zoom
イベント公式言語: 英語

Tracing link of cell ageing and disease progression: Joining factors and facilitators
2024年4月25日(木) 16:00  17:00
ラジクマール・シング カルラ (沖縄科学技術大学院大学 (OIST) 免疫シグナルユニット 研究員)
Cell ageing is an inevitable biological process. It marks declined homeostatic processes in a cell, the impact of which is reflected in the organism’s function/physiology. Ageing, thus, raises risks of disease progression in elderly people and compromises their immunity. Progression of cancer and neurodegenerative diseases and weak immune response against a pathogen(s) represent cases of ageingrelated diseases. What molecular factors/signaling could be associated with disease progression or take part in governing such decisions in aging? – remained a key focus of my research so far. In my talk, I shall shed light on the part characterizing key proteins and their signalling in ageingrelated diseases with an emphasis on cancer, neurodegenerative disease, and immunity. Taking advantage of wet lab and system biology studying gene networks, and genomic, proteomic, and metabolomic readouts, I investigated the molecular expression and processes impacted and compromised by ageing. I shall be discussing new knowledge from my work on the linkage of cell ageing and disease progression and therein role of key factors and facilitators I studied.
会場: via Zoom
イベント公式言語: 英語

セミナー
A night out with ghosts
2024年4月24日(水) 16:00  17:30
Veronica Errasti Diez (Research Fellow, Faculty of Physics, LudwigMaximiliansUniversität München, Germany)
Field theories are the chief theoretical framework for physics. For instance, the Standard Model and General Relativity are widely accepted as accounting for subatomic particle and gravitational behavior, respectively. Nonetheless, even such acclaimed field theories have their limitations, such as the mysterious neutrino masses and dark sector. A natural and popular way around the hurdles consists in generalizations of field theories, via the inclusion of nonlinear and/or higherorder corrections. Unless painstakingly avoided, these corrections lead to the propagation of negative kinetic energy modes, or ghosts for short. Ghosts have earned an appalling fame: kill, exorcise, avoid… No efforts are spared to guarantee their absence. In this talk, we will delve into the root causes for the ill name of ghosts. As a result, we will take up the cudgels for ghosts. While they do have a strong tendency to yield illbehaved theories, ghosts are not intrinsically pathological. As we will see, goodnatured ghosts open the door to multidisciplinary tantalizing opportunities…! And ghosts make excellent partygoers, so make sure not to miss this appointment!
会場: 研究本館 3階 359号室とZoomのハイブリッド開催
イベント公式言語: 英語

セミナー
Zooming into the ancient world by reconstructing the joint genealogies of modern and ancient humans
2024年4月18日(木) 16:00  18:00
Leo Speidel (Senior Research Fellow, Genetics Institute, University College London, UK)
In recent years, we have gone from databases that store the genetic differences observed between hundreds of thousands of sequenced people to using this information to build the actual genetic trees that relate individuals through their shared ancestors back in time. These genetic trees describe how our genomes have evolved up to millions of years into the past. Additionally, sequencing of DNA from ancient human bone has enabled the direct observation of genomic change over past millennia and has unlocked numerous previously hidden genetic histories. In this talk, I will illustrate how we can unearth the human past from these data, ranging from ancient migrations out of Africa and subsequent mixtures with now extinct Neanderthals to waves of ancestry transformations in a nation’s recent past.
会場: via Zoom
イベント公式言語: 英語

セミナー
Quantum FineGrained Complexity
2024年4月18日(木) 10:30  12:00
Harry Buhrman (Chief Scientist for Algorithms and Innovation, Quantinuum, UK)
(The speaker is also a professor at University of Amsterdam & QuSoft. This is a joint seminar with the iTHEMS Quantum Computation Study Group.) One of the major challenges in computer science is to establish lower bounds on the resources, typically time, that are needed to solve computational problems, especially those encountered in practice. A promising approach to this challenge is the study of finegrained complexity, which employs special reductions to prove time lower bounds for many diverse problems based on the conjectured hardness of key problems. For instance, the problem of computing the edit distance between two strings, which is of practical interest for determining the genetic distance between species based on their DNA, has an algorithm that takes O(n^2) time. Through a finegrained reduction, it can be demonstrated that a faster algorithm for edit distance would imply a faster algorithm for the Boolean Satisfiability (SAT) problem. Since faster algorithms for SAT are generally considered unlikely to exist, this implies that faster algorithms for the edit distance problem are also unlikely to exist. Other problems used for such reductions include the 3SUM problem and the All Pairs Shortest Path (APSP) problem. The quantum regime presents similar challenges; almost all known lower bounds for quantum algorithms are defined in terms of query complexity, which offers limited insight for problems where the bestknown algorithms take superlinear time. Employing finegrained reductions in the quantum setting, therefore, represents a natural progression. However, directly translating classical finegrained reductions to the quantum regime poses various challenges. In this talk, I will present recent results in which we overcome these challenges and prove quantum time lower bounds for certain problems in BQP, conditioned on the conjectured quantum hardness of, for example, SAT (and its variants), the 3SUM problem, and the APSP problem. This presentation is based on joint works with Andris Ambainis, Bruno Loff, Florian Speelman, and Subhasree Patro.
会場: セミナー室 (359号室) (メイン会場) / via Zoom
イベント公式言語: 英語

セミナー
Sustainable Organic Synthesis with Abundant Resources
2024年4月15日(月) 13:00  14:00
浅子 壮美 (理化学研究所 環境資源科学研究センター (CSRS) 機能有機合成化学研究チーム 上級研究員)
The sustainable development of modern society necessitates technologies that harness earthabundant metals and organic resources, minimizing reliance on scarce materials. This presentation will introduce our recent efforts towards this goal. We have developed sustainable organic synthesis using sodium dispersion, a molybdenumquinone species for the diazofree generation of carbene species from stable and readily available compounds, and a SpiroBpy ligand that enables the siteselective functionalization of arenes under remote steric control. I will also share some of the challenges we face in developing these reactions in order to ensure reproducibility.
会場: 研究本館 3階 共有スペース
イベント公式言語: 英語

セミナー
ShortLived Hawking Radiation Under Stringy Effects
2024年4月11日(木) 13:30  15:00
WeiHsiang Shao (Ph.D. Student, Department of Physics, National Taiwan University, Taiwan)
A UV theory is required in order to describe the origin of latetime Hawking radiation. In this talk, I will explore Hawking radiation in a nonlocal model of the radiation field inspired by Witten's open string field theory. An attempt at extracting the correlators of this theory will be discussed, which leads to a spacetime uncertainty relation. As a result, the characteristics of transPlanckian field modes differ significantly from that in the standard lowenergy effective theory, and I will argue that this ultimately results in the termination of Hawking radiation around the scrambling time of the black hole.
会場: 研究本館 3階 359号室とZoomのハイブリッド開催
イベント公式言語: 英語

セミナー
A socioecological and genomic approach to mixedspecies formation of African forest guenons
2024年4月4日(木) 16:00  17:00
北山 遼 (北海道大学 大学院環境科学院 博士課程)
While many animal groups consist of a single species, some species have been observed forming mixedspecies groups (MSGs). It is thought that by forming groups with different species, animals may reduce predation risk, improve foraging efficiency, and even gain social and reproductive benefits. Redtailed monkeys and blue monkeys, African forest guenons (Tribe Cercopithecini), are known to form MSGs in several regions in Africa, despite the large niche overlap. The underlying mechanisms driving the formation of MSGs in redtailed monkeys and blue monkeys are still unclear. One reason is that previous studies have been limited to behavioral ecological approaches. By combining field observations with genomic analyses in the laboratory, we seek to shed light on the role of genetic factors in mediating interspecies interactions within MSGs. In this talk, I will introduce our studies on genomic introgression and gut microbiome sharing within the mixedspecies population of redtailed monkeys and blue monkeys in the Kalinzu Forest Reserve, Uganda.
会場: via Zoom
イベント公式言語: 英語

Quantum simulation of QCD matter: from hadronic scattering to gauge field qubit encoding
2024年4月3日(水) 10:00  11:00
Tianyin Li (Ph.D. Student, Institute of Quantum Matter, South China Normal University, China)
Recently, quantum computing (QC) has become a new method for solving nonperturbative problems in highenergy physics. Compared to traditional Monte Carlo simulations, the QC method does not encounter the sign problem, making it an effective approach for solving dynamical and finite density problems. The first part of this talk focuses on the quantum simulation of the hadronic scattering process, including the initial state parton distribution functions, intermediate state partonic scattering amplitudes, and final state hadronization. The second part of this talk concentrates on the qubit encoding of Hamiltonian formalism in lattice gauge field theory with a Coulomb gauge. As a preliminary attempt, the qubit encoding of (3+1)dimensional Coulomb gauge QED will be discussed.
会場: via Zoom
イベント公式言語: 英語

セミナー
Coarsegraining black holes out of equilibrium with boundary observables on time slice
2024年4月1日(月) 16:00  17:30
竹田 大地 (京都大学 素粒子論研究室 博士課程)
In black hole thermodynamics, defining coarsegrained entropy for dynamical black holes has long been a challenge, and various proposals, such as generalized entropy, have been explored. Guided by the AdS/CFT, we introduce a new definition of coarsegrained entropy for a dynamical black hole in Lorentzian Einstein gravity. On each time slice, this entropy is defined as the horizon area of an auxiliary Euclidean black hole that shares the same mass, (angular) momenta, and asymptotic normalizable matter modes with the original Lorentzian solution. The entropy is shown to satisfy a generalized first law within Einstein theory and, through holography, the second law as well. This second law corresponds to the positivity of the relative entropy in the CFT. Furthermore, by applying this thermodynamics to several Vaidya models in AdS and flat spacetime, we discover a connection between the second law and the null energy condition.
会場: セミナー室 (359号室) (メイン会場) / via Zoom
イベント公式言語: 英語

A Selective Survey of Ideas, Tools and Results in Constructive QFT II
2024年4月1日(月) 13:00  14:30
クリスティ・コウジ・ケリー (数理創造プログラム 基礎科学特別研究員)
In this talk we continue to discuss the constructive programme in rigorous QFT. Our aim is discuss a few points on difficulties in relation to the definition of Euclidean path integrals and the general strategy of constructive field theory from a constructive perspective. This will motivate a discussion of the fundamental results in probability theory which are the main tools for the construction of Euclidean path integral measures. We might also discuss some points in relation to free fields, including in particular difficulties in the characterisation of massless fields.
会場: via Zoom / セミナー室 (359号室)
イベント公式言語: 英語

セミナー
Fast Rotating Neutron Stars: Spectra, Stability and Universal Relations
2024年3月27日(水) 11:00  12:30
クリスチャン・クルーガー (Postdoctoral Researcher, University of Tuebingen, Germany)
In this talk, we study rapidly rotating relativistic stars which are present in various astrophysical systems. First, we study their oscillations and instabilities by taking into account the contribution of a dynamic spacetime. The study is based on the linearised version of Einstein’s equations and via this approach the oscillation frequencies as well as the critical values for the onset of a secular instability are determined. We show asteroseismological relations for the fundamental eigenfrequency which are crucial for tackling the inverse problem. Further, we provide universal relations that allow to estimate the moment of inertia (and other bulk quantities) from the knowledge of the triple mass, radius and moment of inertia of an associated nonrotating star. The proposed universal relations facilitate computationally cheap EOS inference codes that permit the inclusion of observations of rotating neutron stars. As a demonstration, we deploy them into a recent Bayesian framework for equation of state parameter estimation that is now valid for arbitrary, uniform rotation. The results are important for all stages of a neutron star’s life but particularly interesting in pre and postmerger cases. This seminar is held by GWEOS WG in iTHEMS.
会場: セミナー室 (359号室) (メイン会場) / via Zoom
イベント公式言語: 英語

セミナー
Arrhythmic activity rhythms in ants
2024年3月26日(火) 16:00  17:00
藤岡 春菜 (岡山大学 環境生命自然科学学域 助教)
Most organisms exhibit a periodic activity of about 24 h. This circadian rhythm is considered to be an adaptation to the fluctuations of the environment. In social insects such as honeybees and ants, individual behavior, including activityrest rhythms, is influenced by interactions within the colony. However, it is challenging to monitor individual activityrest rhythms in an ant colony due to their large group size and small body size. To address this, we developed an imagebased tracking system using 2D barcodes a monomorphic ant and measured the locomotor activities of all colony members under laboratory conditions. Activityrest rhythms appeared only in isolated ants, not under colony conditions. This suggests that a mixture of social interactions, not light and temperature, induces the loss of activityrest rhythms. These findings contribute to our understanding of the diverse patterns of circadian activity rhythms in social insects.
会場: via Zoom
イベント公式言語: 英語

セミナー
Multimessenger probes of superheavy dark matter decay and annihilation
2024年3月26日(火) 10:18  11:00
Saikat Das (京都大学 基礎物理学研究所 ポスドク研究員)
We revisit constraints on decaying very heavy dark matter (VHDM) using the latest ultrahighenergy cosmicray (UHECR; E >1e18 eV) data and ultrahighenergy (UHE) gammaray flux upper limits, measured by the Pierre Auger Observatory. We present updated limits on the VHDM lifetime for masses up to ∼ 1e15 GeV, considering decay into quarks, leptons, and massive bosons. In particular, we consider not only the UHECR spectrum but their composition data that favors heavier nuclei. Such a combined analysis improves the limits at <1e12 GeV because VHDM decay does not produce UHECR nuclei. We also show that the constraints from the UHE gammaray upper limits are ∼ 10 times more stringent than that obtained from cosmic rays, for all of the Standard Model final states we consider. The latter improves our limits to VHDM lifetime by a factor of two for dark matter mass >1e12 GeV. We also provide constraints using neutrino flux from dark matter decay, including the neutrinoinduced cascades. We consider the interaction of UHE neutrinos with the cosmic neutrino background, leading to the attenuation of the extragalactic flux reaching Earth, which improves our analysis to obtain tighter constraints.
会場: via Zoom
イベント公式言語: 英語

セミナー
The evolution of unusual inheritance and chromosome behaviour in flies and other critters
2024年3月14日(木) 16:00  17:00
Laura Ross (Senior Lecturer, Institute of Evolutionary Biology, University of Edinburgh, UK)
Under Mendelian inheritance, individuals receive one set of chromosomes from each of their parents, and transmit one set of these chromosomes at random to their offspring. Yet, in thousands of animals Mendel's laws are broken and the transmission of maternal and paternal alleles becomes unequal. Why such nonMendelian reproductive systems have evolved repeatedly across the tree of life remains unclear. My lab studies a variety of arthropod species to understand why, when and how the transmission of genes from one generation to the next deviate from Mendel’s laws. We mainly focus on species with Paternal Genome Elimination: Males transmit only those chromosomes they inherited from their mother to their offspring, while paternal chromosomes are excluded from sperm through meiotic drive. I will present recent work aimed at understanding the evolution of this unusual reproductive strategy in a clade of flies. These flies arguably have one of the most bizarre and complex chromosome systems of any insect and we use this complexity to study a range of topics including the evolution of sex chromosomes, germlinerestricted chromosomes and sexual conflict.
会場: セミナー室 (359号室) / via Zoom
イベント公式言語: 英語
646 イベント
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