Seminar
605 events
-
Seminar
Finding and understanding disease-causing genetic mutations
June 20 (Thu) at 16:00 - 17:00, 2024
Kojima Shohei (Special Postdoctoral Researcher, Genome Immunobiology RIKEN Hakubi Research Team, RIKEN Center for Integrative Medical Sciences (IMS))
Disease is caused by genetic factors and environmental factors. Genome-wide association study (GWAS) is a powerful method to find genetic factors associated with disease and human complex traits. One conceptual finding GWAS revealed is that many common diseases are caused by a combination of multiple genetic factors (polygenic), rather than a single causal mutation (monogenic). I have been working on finding genetic factors causing polygenic diseases by developing software that accurately finds sequence insertions and deletions from human population-scale sequencing datasets. In this talk, first, I will introduce some examples of disease-causing variants we recently discovered. Next I will also introduce my current research theme aiming to untangle how multiple genetic factors coordinately change cellular homeostasis, which I would like to have a collaboration with mathematical scientists.
Venue: Hybrid Format (3F #359 and Zoom), Main Research Building
Event Official Language: English
-
Seminar
Black hole graviton and quantum gravity
May 16 (Thu) at 15:00 - 16:30, 2024
Yusuke Kimura (Research Scientist, Analytical quantum complexity RIKEN Hakubi Research Team, RIKEN Center for Quantum Computing (RQC))
Drawing from a thought experiment that we conduct, we propose that a virtual graviton gives rise to a black hole geometry when its momentum surpasses a certain threshold value on the Planck scale. This hypothesis implies that the propagator of a virtual graviton, that possesses momentum surpassing this threshold, vanishes. Consequently, a Feynman diagram containing this type of graviton propagator does not add to the overall amplitude. This mechanism suggests the feasibility of formulating an ultraviolet-finite four-dimensional quantum gravitational theory. The elementary particles including the gravitons are treated as point particles in this formulation.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Quantum Computing in Omics Medicine
May 10 (Fri) at 16:00 - 17:15, 2024
Tatsuhiko Tsunoda (Professor, Department of Biological Sciences, Graduate School of Science, The University of Tokyo)
(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 real-time. Meaningful interpretation of these rich data requires an ability to understand high-order 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 large-scale and of ultra-high dimensionality, they are also often sparse, with many missing values in the measurements and frequent higher-order 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 image-like representation for analysis with deep learning (DeepInsight) and have successfully used it to predict drug response and to identify original cell types from single-cell RNA-seq 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.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Deep Learning for Estimating Two-Body Interactions in Mixed-Species Collective Motion
May 9 (Thu) at 16:00 - 17:00, 2024
Masahito Uwamichi (Project Researcher, Graduate School of Arts and Sciences, The University of Tokyo)
(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 two-body 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 mixed-species interactions.
Venue: Hybrid Format (3F #359 and Zoom), Main Research Building
Event Official Language: English
-
Seminar Today
How Stars End Their Lives
April 26 (Fri) at 14:00 - 15:15, 2024
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 intermediate-mass 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 intermediate-mass stars may lose all of their envelopes as a consequence, leaving white-dwarf remnants. More massive stars experience core collapse, leaving a neutron-star or black-hole remnant, possibly associated with a supernova explosion. I will show how the dramatic recent progress on understanding the core-collapse 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 gravitational-wave detectors (such as LIGO) will allow us to test this theoretical connection.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Tracing link of cell ageing and disease progression: Joining factors and facilitators
April 25 (Thu) at 16:00 - 17:00, 2024
Rajkumar Singh Kalra (Staff Scientist, Immune Signal Unit, Okinawa Institute of Science and Technology Graduate University (OIST))
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 ageing-related 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 ageing-related 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.
Venue: via Zoom
Event Official Language: English
-
Seminar
A night out with ghosts
April 24 (Wed) at 16:00 - 17:30, 2024
Veronica Errasti Diez (Research Fellow, Faculty of Physics, Ludwig-Maximilians-Universität 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 non-linear and/or higher-order 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 ill-behaved theories, ghosts are not intrinsically pathological. As we will see, good-natured ghosts open the door to multi-disciplinary tantalizing opportunities…! And ghosts make excellent party-goers, so make sure not to miss this appointment!
Venue: Hybrid Format (3F #359 and Zoom), Main Research Building
Event Official Language: English
-
Seminar
Zooming into the ancient world by reconstructing the joint genealogies of modern and ancient humans
April 18 (Thu) at 16:00 - 18:00, 2024
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.
Venue: via Zoom
Event Official Language: English
-
Seminar
Quantum Fine-Grained Complexity
April 18 (Thu) at 10:30 - 12:00, 2024
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 fine-grained 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 fine-grained 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 best-known algorithms take super-linear time. Employing fine-grained reductions in the quantum setting, therefore, represents a natural progression. However, directly translating classical fine-grained 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.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Sustainable Organic Synthesis with Abundant Resources
April 15 (Mon) at 13:00 - 14:00, 2024
Sobi Asako (Senior Scientist, Advanced Organic Synthesis Research Team, RIKEN Center for Sustainable Resource Science (CSRS))
The sustainable development of modern society necessitates technologies that harness earth-abundant 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 molybdenum-quinone species for the diazo-free generation of carbene species from stable and readily available compounds, and a SpiroBpy ligand that enables the site-selective 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.
Venue: 3rd floor public space, Main Research Building
Event Official Language: English
-
Seminar
Short-Lived Hawking Radiation Under Stringy Effects
April 11 (Thu) at 13:30 - 15:00, 2024
Wei-Hsiang Shao (Ph.D. Student, Department of Physics, National Taiwan University, Taiwan)
A UV theory is required in order to describe the origin of late-time Hawking radiation. In this talk, I will explore Hawking radiation in a non-local 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 space-time uncertainty relation. As a result, the characteristics of trans-Planckian field modes differ significantly from that in the standard low-energy effective theory, and I will argue that this ultimately results in the termination of Hawking radiation around the scrambling time of the black hole.
Venue: Hybrid Format (3F #359 and Zoom), Main Research Building
Event Official Language: English
-
Seminar
A socio-ecological and genomic approach to mixed-species formation of African forest guenons
April 4 (Thu) at 16:00 - 17:00, 2024
Haruka Kitayama (Ph.D. Student, Graduate School of Environmental Science, Hokkaido University)
While many animal groups consist of a single species, some species have been observed forming mixed-species 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. Red-tailed 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 red-tailed 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 mixed-species population of red-tailed monkeys and blue monkeys in the Kalinzu Forest Reserve, Uganda.
Venue: via Zoom
Event Official Language: English
-
Quantum simulation of QCD matter: from hadronic scattering to gauge field qubit encoding
April 3 (Wed) at 10:00 - 11:00, 2024
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 non-perturbative problems in high-energy 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.
Venue: via Zoom
Event Official Language: English
-
Seminar
Coarse-graining black holes out of equilibrium with boundary observables on time slice
April 1 (Mon) at 16:00 - 17:30, 2024
Daichi Takeda (Ph.D. Student, Theoretical Particle Physics Group, Kyoto University)
In black hole thermodynamics, defining coarse-grained 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 coarse-grained 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.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
A Selective Survey of Ideas, Tools and Results in Constructive QFT II
April 1 (Mon) at 13:00 - 14:30, 2024
Christy Koji Kelly (Special Postdoctoral Researcher, iTHEMS)
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.
Venue: via Zoom / Seminar Room #359
Event Official Language: English
-
Seminar
Fast Rotating Neutron Stars: Spectra, Stability and Universal Relations
March 27 (Wed) at 11:00 - 12:30, 2024
Christian Krueger (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 space-time. 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 non-rotating 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 post-merger cases. This seminar is held by GW-EOS WG in iTHEMS.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Arrhythmic activity rhythms in ants
March 26 (Tue) at 16:00 - 17:00, 2024
Haruna Fujioka (Assistant Professor, Faculty of Environmental, Life, Natural Science and Technology, Okayama University)
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 activity-rest rhythms, is influenced by interactions within the colony. However, it is challenging to monitor individual activity-rest rhythms in an ant colony due to their large group size and small body size. To address this, we developed an image-based tracking system using 2D barcodes a monomorphic ant and measured the locomotor activities of all colony members under laboratory conditions. Activity-rest 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 activity-rest rhythms. These findings contribute to our understanding of the diverse patterns of circadian activity rhythms in social insects.
Venue: via Zoom
Event Official Language: English
-
Seminar
Multimessenger probes of superheavy dark matter decay and annihilation
March 26 (Tue) at 10:18 - 11:00, 2024
Saikat Das (Postdoctoral Fellows, Yukawa Institute for Theoretical Physics, Kyoto University)
We revisit constraints on decaying very heavy dark matter (VHDM) using the latest ultrahigh-energy cosmic-ray (UHECR; E >1e18 eV) data and ultrahigh-energy (UHE) gamma-ray 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 gamma-ray 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 neutrino-induced 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.
Venue: via Zoom
Event Official Language: English
-
Seminar
The evolution of unusual inheritance and chromosome behaviour in flies and other critters
March 14 (Thu) at 16:00 - 17:00, 2024
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 non-Mendelian 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, germline-restricted chromosomes and sexual conflict.
Venue: Seminar Room #359 / via Zoom
Event Official Language: English
-
Seminar
Brane field theory with higher-form symmetry
March 12 (Tue) at 14:00 - 15:30, 2024
Kiyoharu Kawana (Research Fellow, Korea Institute for Advanced Study (KIAS), Republic of Korea)
We propose field theory for branes with higher-form symmetry as a generalization of ordinary Landau theory. The field \psi[C_p^{}] becomes a functional of p-dimensional closed brane Cp embedded in a spacetime. As a natural generalization of ordinary field theory, we call this theory brane field theory. In order to construct an action that is invariant under higher-form transformation, we first generalize the concept of “derivative” for higher-dimensional objects. Then, we discuss various fundamental properties of the brane field based on the higher-form invariant action. It is shown that the classical solution exhibits the area law in the unbroken phase of U(1) p-form symmetry, while it indicates a constant behavior in the broken phase for the large volume limit of Cp. In the latter case, the low-energy effective theory is described by the p-form Maxwell theory. If time permits, we also discuss brane-field theories with a discrete higher-form symmetry and show that the low-energy effective theory becomes a BF-type topological field theory, resulting in topological order.
Venue: Hybrid Format (3F #359 and Zoom), Main Research Building
Event Official Language: English
605 events
Events
Categories
series
- iTHEMS Colloquium
- MACS Colloquium
- iTHEMS Seminar
- iTHEMS Math Seminar
- DMWG Seminar
- iTHEMS Biology Seminar
- iTHEMS Theoretical Physics Seminar
- Information Theory SG Seminar
- Quantum Matter Seminar
- ABBL-iTHEMS Joint Astro Seminar
- Math-Phys Seminar
- Quantum Gravity Gatherings
- RIKEN Quantum Seminar
- Quantum Computation SG Seminar
- NEW WG Seminar
- Lab-Theory Standing Talks
- QFT-core Seminar
- STAMP Seminar
- QuCoIn Seminar
- Number Theory Seminar
- Berkeley-iTHEMS Seminar
- iTHEMS-RNC Meson Science Lab. Joint Seminar
- Academic-Industrial Innovation Lecture
- RIKEN Quantum Lecture
- Theory of Operator Algebras
- iTHEMS Intensive Course-Evolution of Cooperation
- Introduction to Public-Key Cryptography
- Knot Theory
- iTHES Theoretical Science Colloquium
- SUURI-COOL Seminar
- iTHES Seminar