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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240516T130000
DTEND;TZID=America/New_York:20240516T140000
DTSTAMP:20260405T140106
CREATED:20240416T181859Z
LAST-MODIFIED:20240510T175438Z
UID:10003377-1715864400-1715868000@cmsa.fas.harvard.edu
SUMMARY:Controlling chaotic advection in 2D active nematics
DESCRIPTION:Active Matter Seminar \nSpeaker: Kevin Mitchell\, University of California\, Merced \nTitle: Controlling chaotic advection in 2D active nematics \nAbstract: Recent years have seen a surge of interest in active materials\, in which energy injected at the microscale gives rise to mesoscale coherent motion. One prominent example is an active 2D “liquid crystal” composed of microtubules in the nematic phase. The activity is generated by molecular motors that consume ATP to generate local shearing between the microtubules. The resulting 2D fluid flow exhibits self-generated mesoscale chaotic dynamics with a characteristic folding and stretching pattern. We analyze this dynamics from the perspective of chaotic advection\, in which the fluid can be viewed as “stirred” by topological defects in the nematic order parameter. Typically\, these defects move in an irregular\, chaotic pattern. We explore conditions\, both theoretically and in experiments\, under which the topological defects can be coaxed to perform regular periodic motion\, thus bringing some degree of order to the chaos.
URL:https://cmsa.fas.harvard.edu/event/active-matter-51624/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-05.16.2024.docx-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240502T133000
DTEND;TZID=America/New_York:20240502T143000
DTSTAMP:20260405T140106
CREATED:20240416T181909Z
LAST-MODIFIED:20240430T131929Z
UID:10003376-1714656600-1714660200@cmsa.fas.harvard.edu
SUMMARY:Non-dispersive one-way signal amplification in sonic metamaterials
DESCRIPTION:Active Matter Seminar \nSpeaker: Jayson Paulose\, University of Oregon \nTitle: Control of parametric amplification in space-time modulated mechanical metamaterials \nAbstract: Active mechanical metamaterials harbor acoustic signal processing functionalities that are impossible to achieve in passive structures. Amplifying an elastic wave as it passes through the material is a prominent example\, with potential applications in acoustic signal processing and loss mitigation. The fundamental mechanism for signal amplification of this kind is the parametric amplifier–an oscillator whose stiffness is periodically modulated in time\, which can inject energy into mechanical oscillations. Typically\, parametric amplification occurs at distinct modulation frequencies that are trivially related to the resonance modes of the unmodulated system\, which restricts its utility for amplifying signals with complex spatial or spectral structure. In this talk\, I’ll show how spatial variation of the modulation phase in parametric oscillator networks enables amplification phenomena that are far richer than those achievable by uncoupled and uncoordinated parametric amplifiers. Examples include turning off parametric resonances for particular vibrational modes in small assemblies [1]\, and achieving nonreciprocal broadband amplification in periodic arrays [2]. The existence of parametric resonances is tied to the internal symmetries inherent to mechanical systems as well as the symmetries obeyed by the parametric variation in space and time\, through an exact theoretical framework that augments the standard Floquet analysis of space-time modulated systems. \n  \n[1] Melkani and Paulose\, arXiv:2310.08734 \n[2] Kruss and Paulose\, PRApplied17\, 024020 (2022)
URL:https://cmsa.fas.harvard.edu/event/active-matter-5224/
LOCATION:Jefferson 256\, 17 Oxford Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-05.02.2024-2.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240404T130000
DTEND;TZID=America/New_York:20240404T140000
DTSTAMP:20260405T140106
CREATED:20240328T161543Z
LAST-MODIFIED:20240401T210220Z
UID:10003353-1712235600-1712239200@cmsa.fas.harvard.edu
SUMMARY:Shape morphing with swelling hydrogels and expanding foams
DESCRIPTION:Active Matter Seminar \nSpeaker: Abby Plummer\, Boston University \nTitle: Shape morphing with swelling hydrogels and expanding foams \nAbstract: Materials that increase in size offer intriguing possibilities for shape-morphing applications. Here\, we explore two such systems—swelling polyacrylamide hydrogels and expanding polyurethane foams. The hydrogels swell by absorbing water into crosslinked polymer networks. They can therefore be modeled by coupling solvent migration with the deformations of a hyperelastic solid. In contrast\, the foams initially behave as liquids with viscosity and volume increasing in time\, responding elastically only when close to solidification. We investigate how these expanding materials are sculpted by complex environments with obstacles and trenches.
URL:https://cmsa.fas.harvard.edu/event/active-matter-4424/
LOCATION:Hybrid – G10
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-04.04.2024.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240321T130000
DTEND;TZID=America/New_York:20240321T140000
DTSTAMP:20260405T140106
CREATED:20240314T184932Z
LAST-MODIFIED:20240318T140916Z
UID:10002912-1711026000-1711029600@cmsa.fas.harvard.edu
SUMMARY:Decoding The Origins of Fluidity in Multicellular Systems
DESCRIPTION:Active Matter Seminar \nSpeaker: Max Bi (Northeastern University) \nTitle: Decoding The Origins of Fluidity in Multicellular Systems \nAbstract: Organisms continually adapt to mechanical forces at the cellular and tissue levels\, a process crucial for sustaining vital life functions. In pivotal physiological processes\, such as cancer progression and embryonic development\, tissues are often poised near solid-like and fluid-like states. My talk will delve into three critical aspects of this phenomenon: (1) utilizing computational models that draw parallels with soft matter physics\, we examine shear-induced rigidity and the origins of fluidity in epithelial tissues; (2) exploring the intricate relationship between external mechanical stresses and internal cellular dynamics\, unraveling a range of rheological behaviors\, such as shear thinning and thickening\, which are key for understanding rheological responses in varying physical contexts; and (3) investigating how cellular processes like division and apoptosis influence tissue states\, with a specific focus on the emergence of hexatic phases\, an intermediate state exhibiting properties of both solids and liquids.
URL:https://cmsa.fas.harvard.edu/event/activematter-32124/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-03.21.2024.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240229T130000
DTEND;TZID=America/New_York:20240229T140000
DTSTAMP:20260405T140106
CREATED:20240222T194931Z
LAST-MODIFIED:20240226T155546Z
UID:10002812-1709211600-1709215200@cmsa.fas.harvard.edu
SUMMARY:Directed motion in active matter: Frictiotaxis and flocking
DESCRIPTION:Active Matter Seminar \nSpeaker: Ricard Alert\, Max Planck Institute for the Physics of Complex Systems \nTitle: Directed motion in active matter: Frictiotaxis and flocking \nAbstract: A key feature of active matter is its ability to move directionally\, both as individual particles and collectively. I will discuss two examples of directed motion: one in cell migration\, and one in collections of self-propelled colloids. First\, I will show that cells lacking cell-substrate adhesions migrate along friction gradients. We call this phenomenon frictiotaxis\, which is a new type of cell guidance. Second\, I will present a new mechanism for flocking whereby self-propelled particles can align and move collectively despite turning away from each other.
URL:https://cmsa.fas.harvard.edu/event/active-matter-22924/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-02.29.2024.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231207T130000
DTEND;TZID=America/New_York:20231207T140000
DTSTAMP:20260405T140106
CREATED:20240223T055715Z
LAST-MODIFIED:20240223T055715Z
UID:10002823-1701954000-1701957600@cmsa.fas.harvard.edu
SUMMARY:Active structures and flows in living cells
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Michael Shelley (Flatiron) \nTitle: Active structures and flows in living cells \nAbstract: Flows in the fluidic interior of living cells can serve biological function or act as signatures of how intracellular forces are exerted. I’ll discuss examples of each. One is understanding the emergence of cell-spanning vortical flows in large developing egg cells\, while the other arises in studying the nature of force transduction in single cell embryos moving towards their first cell division. Both involve the cytoskeleton\, that set of polymers\, cross-linkers\, and molecular motors that underlie much of the active mechanics within cells\, and has led to the development of new coarse-grained active matter models and novel instabilities.
URL:https://cmsa.fas.harvard.edu/event/am-12723/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-12.07.23.docx-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231109T130000
DTEND;TZID=America/New_York:20231109T140000
DTSTAMP:20260405T140106
CREATED:20240223T060824Z
LAST-MODIFIED:20240223T060824Z
UID:10002824-1699534800-1699538400@cmsa.fas.harvard.edu
SUMMARY:Nuclear chromodynamics: non-equilibrium phase transition in the nucleus of a living cell
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Alexander Grosberg (NYU)\n\nTitle: Nuclear chromodynamics: non-equilibrium phase transition in the nucleus of a living cell \nAbstract: Nucleus of a living cell houses a cell genome – a polymer called chromatin\, which is a functional form of DNA.  It is very long\, e.g.\, 2 meters long for every human cell.  Nucleus is also an arena of incessant energy-driven activity.  Experiments show that chromatin undergoes large scale motions sustained over long times of order seconds.  In the talk\, after reviewing the phenomenology\, I will show how these flows may arise due to a phase transition in which chromatin-driving motors\, such as RNA polymerase\, form a polar (“ferromagnetic”) order controlled by hydrodynamic interactions.  The talk is based on the joint work with I.Eshghi and A.Zidovska.
URL:https://cmsa.fas.harvard.edu/event/am-11923/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-11.09.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231026T130000
DTEND;TZID=America/New_York:20231026T140000
DTSTAMP:20260405T140106
CREATED:20240223T070828Z
LAST-MODIFIED:20240223T070828Z
UID:10002825-1698325200-1698328800@cmsa.fas.harvard.edu
SUMMARY:Scaling behavior and control of nuclear wrinkling
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Nicolas Romeo (UChicago) \nTitle: Scaling behavior and control of nuclear wrinkling \nAbstract: The cell nucleus is enveloped by a complex membrane\, whose wrinkling has been implicated in disease and cellular aging. The biophysical dynamics and spectral evolution of nuclear wrinkling during multicellular development remain poorly understood due to a lack of direct quantitative measurements. We characterize the onset and dynamics of nuclear wrinkling during egg development in the fruit fly when nurse cell nuclei increase in size and display stereotypical wrinkling behaviour. A spectral analysis of three-dimensional high-resolution live-imaging data from several hundred nuclei reveals a robust asymptotic power-law scaling of angular fluctuations consistent with renormalization and scaling predictions from a nonlinear elastic shell model. We further demonstrate that nuclear wrinkling can be reversed through osmotic shock and suppressed by microtubule disruption\, providing tunable physical and biological control parameters for probing the mechanical properties of the nuclear envelope\, highlighting in passing the importance of nonlinear response to biological robustness.
URL:https://cmsa.fas.harvard.edu/event/am-102623/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-10.26.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231012T130000
DTEND;TZID=America/New_York:20231012T140000
DTSTAMP:20260405T140106
CREATED:20240223T072135Z
LAST-MODIFIED:20240223T072135Z
UID:10002826-1697115600-1697119200@cmsa.fas.harvard.edu
SUMMARY:Contractility\, structure formation and fluctuations in active gels\, with and without molecular motors
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Fred MacKintosh (Rice University) \nTitle: Contractility\, structure formation and fluctuations in active gels\, with and without molecular motors \nAbstract: Various processes in living cells depend on contractile forces that are often generated by myosin motors in concert with polar actin filaments. A textbook example of this is the actomyosin contractile ring that forms during cell division. Recent evidence\, however\, has begun to suggest alternate or redundant mechanisms that do not depend on myosin. Experiments on simplified\, reconstituted systems also point to contractility and structure formation in disordered\, apolar arrays of filaments. We propose a motor-free mechanism that can generate contraction in biopolymer networks without the need for motors such as myosin or polar filaments such as actin. This mechanism is based on active binding and unbinding of cross-linkers that breaks the principle of detailed balance\, together with the asymmetric force-extension response of semiflexible biopolymers. We discuss the resulting force-velocity relation and other implications of this\, as well as possible evidence for non-motor force generation.
URL:https://cmsa.fas.harvard.edu/event/am-101223/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-10.12.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230928T130000
DTEND;TZID=America/New_York:20230928T140000
DTSTAMP:20260405T140106
CREATED:20240223T072654Z
LAST-MODIFIED:20240223T072654Z
UID:10002827-1695906000-1695909600@cmsa.fas.harvard.edu
SUMMARY:Strongly driven mixtures and membranes: Out of equilibrium surprises 
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Max Lavrentovich\, Worcester State University \nTitle: Strongly driven mixtures and membranes: Out of equilibrium surprises \nAbstract: The more prosaic cousin of active matter\, driven inactive matter\, is still full of unexpected phenomena. I will discuss two projects involving two seemingly mundane systems\, a phase-separating colloidal mixture and a lipid membrane\, which demonstrate counterintuitive properties when driven out of equilibrium. We will see that the phase separating mixture\, when driven by a uniform force\, develops (in simulations) an intriguing pattern with a characteristic length scale set by the magnitude of the drive. We will look at some theoretical approaches to understanding the pattern formation and possible experimental realizations. The membrane\, when driven by an oscillatory electric field\, develops (in experiments) a long-lived metastable state with a decreased capacitance and increased dissipation. This state may have implications for neuronal processing and memory formation.
URL:https://cmsa.fas.harvard.edu/event/am-92823/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-09.28.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230914T130000
DTEND;TZID=America/New_York:20230914T140000
DTSTAMP:20260405T140106
CREATED:20240223T111752Z
LAST-MODIFIED:20240223T111752Z
UID:10002860-1694696400-1694700000@cmsa.fas.harvard.edu
SUMMARY:Frustration-free states of cell fate networks: the case of the epithelial-mesenchymal transition
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Herbert Levine (Northeastern)\n\nTitle: Frustration-free states of cell fate networks: the case of the epithelial-mesenchymal transition\n\nAbstract: Cell fate decisions are made by allowing external signals to govern the steady-state pattern adopted by networks of interacting regulatory factors governing transcription and translation. One of these decisions\, of importance for both developmental processes and for cancer metastasis\, is the epithelial-mesenchymal transition (EMT). In this talk\, we will argue that these biological networks have highly non-generic interaction structures such that they allow for phenotypic states with very low frustration\, i.e. where most interactions are satisfied. This property has important consequences for the allowed dynamics of these systems.
URL:https://cmsa.fas.harvard.edu/event/am-91423/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230511T130000
DTEND;TZID=America/New_York:20230511T140000
DTSTAMP:20260405T140106
CREATED:20230724T183239Z
LAST-MODIFIED:20240228T071614Z
UID:10002747-1683810000-1683813600@cmsa.fas.harvard.edu
SUMMARY:Insights from single cell lineage trees
DESCRIPTION:Active Matter Seminar\n\n\n\n\nSpeaker: Sahand Hormoz\, Harvard Medical School\, Dana-Farber Cancer Institute\n\n\n\n\nTitle: Insights from single cell lineage trees\n\n\n\n\nAbstract: In this talk\, I will discuss two recent projects from my lab that involve lineage trees of cells (the branching diagram that represents the ancestry and division history of individual cells). In the first project\, we reconstructed the lineage trees of individual cancer cells from the patterns of randomly occurring mutations in these cells. We then inferred the age at which the cancer mutation first occurred and the rate of expansion of the population of cancer cells within each patient. To our surprise\, we discovered that the cancer mutation occurs decades before diagnosis. For the second project\, we developed microfluidic ‘mother machines’ that allow us to observe mammalian cells dividing across tens of generations. Using our observations\, we calculated the correlation between the duration of cell cycle phases in pairs of cells\, as a function of their lineage distance. These correlations revealed many surprises that we are trying to understand using hidden Markov models on trees. For both projects\, I will discuss the mathematical challenges that we have faced and open problems related to inference from lineage trees.
URL:https://cmsa.fas.harvard.edu/event/am-51123/
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-05.11.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230427T130000
DTEND;TZID=America/New_York:20230427T140000
DTSTAMP:20260405T140106
CREATED:20230824T183024Z
LAST-MODIFIED:20240209T052245Z
UID:10001810-1682600400-1682604000@cmsa.fas.harvard.edu
SUMMARY:Competition at the front of expanding populations
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Mehran Kardar\, MIT \nTitle: Competition at the front of expanding populations \nAbstract: When competing species grow into new territory\, the population is dominated by descendants of successful ancestors at the expansion front. Successful ancestry depends on the reproductive advantage (fitness)\, as well as ability and opportunity to colonize new domains. (1) Based on symmetry considerations\, we present a model that  integrates both elements by coupling the classic description of one-dimensional competition (Fisher equation) to the minimal model of front shape (KPZ equation). Macroscopic manifestations of these equations on growth morphology are explored\, providing a framework to study spatial competition\, fixation\, and differentiation\, In particular\, we find that ability to expand in space may overcome reproductive advantage in colonizing new territory. (2) Variations of fitness\, as well as fixation time upon differentiation\, are shown to belong to distinct universality classes depending on limits to gain of fitness.
URL:https://cmsa.fas.harvard.edu/event/am-42723/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=:
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230413T130000
DTEND;TZID=America/New_York:20230413T140000
DTSTAMP:20260405T140106
CREATED:20230824T182821Z
LAST-MODIFIED:20240216T112442Z
UID:10001811-1681390800-1681394400@cmsa.fas.harvard.edu
SUMMARY:Control of actin cable length by decelerated growth and network geometry
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Shane McInally\, Brandeis \nTitle: Control of actin cable length by decelerated growth and network geometry \nAbstract: The sizes of many subcellular structures are coordinated with cell size to ensure that these structures meet the functional demands of the cell. In eukaryotic cells\, these subcellular structures are often membrane-bound organelles\, whose volume is the physiologically important aspect of their size. Scaling organelle volume with cell volume can be explained by limiting pool mechanisms\, wherein a constant concentration of molecular building blocks enables subcellular structures to increase in size proportionally with cell volume. However\, limiting pool mechanisms cannot explain how the size of linear subcellular structures\, such as cytoskeletal filaments\, scale with the linear dimensions of the cell. Recently\, we discovered that the length of actin cables in budding yeast (used for intracellular transport) precisely matches the length of the cell in which they are assembled. Using mathematical modeling and quantitative imaging of actin cable growth dynamics\, we found that as the actin cables grow longer\, their extension rates slow (or decelerate)\, enabling cable length to match cell length. Importantly\, this deceleration behavior is cell-length dependent\, allowing cables in longer cells to grow faster\, and therefore reach a longer length before growth stops at the back of the cell. In addition\, we have unexpectedly found that cable length is specified by cable shape. Our imaging analysis reveals that cables progressively taper as they extend from the bud neck into the mother cell\, and further\, this tapering scales with cell length. Integrating observations made for tapering actin networks in other systems\, we have developed a novel mathematical model for cable length control that recapitulates our quantitative experimental observations. Unlike other models of size control\, this model does not require length-dependent rates of assembly or disassembly. Instead\, feedback control over the length of the cable is an emergent property due to the cross-linked and bundled architecture of the actin filaments within the cable. This work reveals a new strategy that cells use to coordinate the size of their internal parts with their linear dimensions. Similar design principles may control the size and scaling of other subcellular structures whose physiologically important dimension is their length.
URL:https://cmsa.fas.harvard.edu/event/am-41323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-04.13.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230330T130000
DTEND;TZID=America/New_York:20230330T140000
DTSTAMP:20260405T140106
CREATED:20230824T182516Z
LAST-MODIFIED:20240228T084556Z
UID:10002748-1680181200-1680184800@cmsa.fas.harvard.edu
SUMMARY:The Role of Orientational Order in Development
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Mark Bowick\, Kavli Institute for Theoretical Physics\, UCSB \nTitle: The Role of Orientational Order in Development \nAbstract: Morphogenesis\, the process through which genes generate form\, establishes tissue scale order as a template for constructing the complex shapes of the body plan. The extensive growth required to build these ordered substrates is fueled by cell proliferation\, which\, naively\, should disrupt order. Understanding how active morphogenetic mechanisms couple cellular and mechanical processes to generate order remains an outstanding question in animal development. I will review the statistical mechanics of orientational order and discuss the observation of a fourfold orientationally ordered phase (tetratic) in the model organism Parhyale hawaiensis. I will also discuss theoretical mechanisms for the formation of orientational order that require both motility and cell division\, with support from self-propelled vertex models of tissue. The aim is to uncover a robust\, active mechanism for generating global orientational order in a non-equilibrium system that then sets the stage for the development of shape and form.
URL:https://cmsa.fas.harvard.edu/event/am-33023/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-03.30.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230316T130000
DTEND;TZID=America/New_York:20230316T140000
DTSTAMP:20260405T140106
CREATED:20230824T181630Z
LAST-MODIFIED:20240215T111640Z
UID:10001504-1678971600-1678975200@cmsa.fas.harvard.edu
SUMMARY:Active chemical reactions in phase-separating systems
DESCRIPTION:Active Matter Seminar \n  \n\n\nSpeaker:  Jonathan Bauermann\, Max Planck Institute for the Physics of Complex Systems \n\n\n\nTitle: Active chemical reactions in phase-separating systems \nAbstract: Motivated by the existence of membrane-less compartments in the chemically active environment of living cells\, I will discuss the dynamics of droplets in the presence of active chemical reactions. Therefore\, I will first introduce the underlying interplay between phase separation and active reactions\, which can alter the droplet dynamics compared to equilibrium systems. A key feature of such systems is the emergence of concentration gradients even at steady states. In the second part of this talk\, I will discuss how these gradients can trigger instabilities in the core of chemically active droplets\, giving rise to a new non-equilibrium steady state of liquid spherical shells. Finally\, I will present experimental and theoretical results discussing the existence and energetic cost of this non-equilibrium steady state in a coacervate system.
URL:https://cmsa.fas.harvard.edu/event/am-31623/
LOCATION:Virtual
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=:
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230216T130000
DTEND;TZID=America/New_York:20230216T140000
DTSTAMP:20260405T140106
CREATED:20230824T181345Z
LAST-MODIFIED:20240130T084532Z
UID:10001503-1676552400-1676556000@cmsa.fas.harvard.edu
SUMMARY:Towards programmable living materials and quantitative models of active matter
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Jörn Dunkel\, MIT \nTitle: Towards programmable living materials and quantitative models of active matter \nAbstract: Over the last two decades\, major progress has been made in understanding the self-organization principles of active matter.  A wide variety of experimental model systems\, from self-driven colloids to active elastic materials\, has been established\, and an extensive theoretical framework has been developed to explain many of the experimentally observed non-equilibrium pattern formation phenomena. Two key challenges for the coming years will be to translate this foundational knowledge into functional active materials\, and to identify quantitative mathematical models that can inform and guide the design and production of such materials. Here\, I will describe joint efforts with our experimental collaborators to realize self-growing bacterial materials [1]\, and to implement computational model inference schemes for active and living systems dynamics [2\,3]. \n[1] Nature 608: 324\, 2022\n[2] PNAS 120: e2206994120\, 2023\n[3] eLife 10: e68679\, 2021
URL:https://cmsa.fas.harvard.edu/event/am-21623/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-02.16.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230202T130000
DTEND;TZID=America/New_York:20230202T140000
DTSTAMP:20260405T140106
CREATED:20230824T181110Z
LAST-MODIFIED:20240215T102236Z
UID:10001317-1675342800-1675346400@cmsa.fas.harvard.edu
SUMMARY:Interacting Active Matter
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Amin Doostmohammadi\, Niels Bohr Institute\, University of Copenhagen \nTitle: Interacting Active Matter \nAbstract: I will focus on the interaction between different active matter systems. In particular\, I will describe recent experimental and modeling results that reveal how interaction forces between adhesive cells generate activity in the cell layer and lead to a potentially new mode of phase segregation. I will then discuss mechanics of how cells use finger-like protrusions\, known as filopodia\, to interact with their surrounding medium. First\, I will present experimental and theoretical results of active mirror-symmetry breaking in subcellular skeleton of filopodia that allows for rotation\, helicity\, and buckling of these cellular fingers in a wide variety of cells ranging from epithelial\, mesenchymal\, cancerous and stem cells. I will then describe in-vivo experiments together with theoretical modeling showing how during embryo development specialized active cells probe and modify other cell layers and integrate within an active epithelium.
URL:https://cmsa.fas.harvard.edu/event/am-2223/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-02.02.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221208T130000
DTEND;TZID=America/New_York:20221208T140000
DTSTAMP:20260405T140106
CREATED:20230824T180707Z
LAST-MODIFIED:20240215T094558Z
UID:10001316-1670504400-1670508000@cmsa.fas.harvard.edu
SUMMARY:Self-organization of motile cells by quorum-sensing or chemotactic interactions
DESCRIPTION:Active Matter Seminar\n\nSpeaker: Julien Tailleur (MIT) \nTitle: Self-organization of motile cells by quorum-sensing or chemotactic interactions \nAbstract: Equilibrium statistical mechanics tells us how to control the self-assembly of passive materials by tuning the competition between energy and entropy to achieve desired states of organization. Out of equilibrium\, no such principles apply and self-organization principles are scarce. Active matter describes systems in which individual units dissipate energy to exert forces on their environment. Dissipation and injection of energy are then disconnected at the microscopic scale\, hence driving the system strongly out of thermal equilibrium. This leads to a phenomenology markedly different from that of equilibrium systems\, such as the emergence of dense phases in the absence of cohesive attractive forces\, but it also leaves us without guiding principles to understand the self-organization of active matter. In this talk\, I will review the progress which has been made over the past ten years to control the organization of self-propelled agents using motility control\, either externally or through interactions. I will show that generic principles apply and illustrate the theoretical developments presented in the talk using recent experiments on the motility-induced self-organization of bacterial mixtures.
URL:https://cmsa.fas.harvard.edu/event/am-12822/
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-12.08.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221117T130000
DTEND;TZID=America/New_York:20221117T140000
DTSTAMP:20260405T140106
CREATED:20230824T175941Z
LAST-MODIFIED:20240122T172011Z
UID:10001315-1668690000-1668693600@cmsa.fas.harvard.edu
SUMMARY:Dynamic and multicolor electron microscopy
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Max Prigozhin (Harvard) \nTitle: Dynamic and multicolor electron microscopy \nAbstract: My lab is developing biophysical methods to achieve multicolor and dynamic biological imaging at the molecular scale. Our approach to capturing the dynamics of cellular processes involves cryo-vitrifying samples after known time delays following stimulation using custom cryo- plunging and high-pressure freezing instruments. To achieve multicolor electron imaging\, we are exploring the property of cathodoluminescence—optical emission induced by the electron beam. We are developing nanoprobes (“cathodophores”) that will be used as luminescent protein tags in electron microscopy. We are applying these new methods to study G-protein- coupled receptor signaling and to visualize the formation of biomolecular condensates.
URL:https://cmsa.fas.harvard.edu/event/am-111722/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-11.17.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221103T130000
DTEND;TZID=America/New_York:20221103T140000
DTSTAMP:20260405T140106
CREATED:20230824T175654Z
LAST-MODIFIED:20240215T094755Z
UID:10001314-1667480400-1667484000@cmsa.fas.harvard.edu
SUMMARY:Force transmission informs the collective behavior of active cell layers
DESCRIPTION:Active Matter Seminar \nSpeaker: Siavash Monfared\, Niels Bohr Institute\, Copenhagen \nTitle: Force transmission informs the collective behavior of active cell layers \nAbstract: Collective cell migration drives numerous physiological processes such as tissue morphogenesis\, wound healing\, tumor progression and cancer invasion. However\, how the interplay of mechanical interactions and the modes of collective self-organization among cells informs such processes is yet to be established. In this talk\, I will focus on the role of three-dimensional force transmission\, from a theoretical and computational perspective\, on two phenomena: (1) cell extrusion from a cellular monolayer and (2) density-independent solid-like to fluid-like transition of active cell layers. For the first topic\, I will focus on how increasing cell-cell adhesion relative to cell-substrate adhesion enables cells to collectively exploit distinct mechanical pathways – leveraging defects in nematic and hexatic phases associated with cellular arrangement – to eliminate an unwanted cell. For the second topic\, I will show how solid-like to fluid-like transition in active cell layers is linked to the percolation of isotropic stresses. This is achieved via two distinct and independent paths to model this transition by increasing (a) cell-cell adhesion and (b) active traction forces. Additionally\, using finite-size scaling analyses\, the phase transition associated with each path is mapped onto the 2D site percolation universality class. Our results highlight the importance of force transmission in informing the collective behavior of living cells and opens the door to new sets of questions for those interested in connecting the physics of cellular self-organization to the dynamics of biological systems. \n 
URL:https://cmsa.fas.harvard.edu/event/am-113022/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-11.03.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20221020T120000
DTEND;TZID=America/New_York:20221020T130000
DTSTAMP:20260405T140106
CREATED:20230824T175351Z
LAST-MODIFIED:20240215T094345Z
UID:10001313-1666267200-1666270800@cmsa.fas.harvard.edu
SUMMARY:Attempts at understanding human axial elongation and patterning
DESCRIPTION:Active Matter Seminar\n\n\n\n\nSpeaker: Sharad Ramanathan\, Harvard\n\n\nTitle: Attempts at understanding human axial elongation and patterning\n\nAbstract: Some of the most dramatic events during human development is the axial elongation of the embryo with concomitant changes in the geometry and composition of the underlying tissues. The posterior part of the embryo gives rise to the spinal cord\, vertebral column\, ribcage\, back muscles\, and dermis.  In this talk\, I will present our attempts at coaxing human embryonic stem cells to form these structures of the early human embryo that closely recapitulate the geometry\, relative arrangements\, composition\, and dynamics of development of the early spinal cord flanked progenitors of the musculoskeletal system. Our goal was to do so\, such that we could build hundreds of these organoids at a time. I will also present preliminary results for the use of this system to understand key events during early human development through imaging and genetic perturbations.
URL:https://cmsa.fas.harvard.edu/event/am-4/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-10.20.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220921T110000
DTEND;TZID=America/New_York:20220921T120000
DTSTAMP:20260405T140106
CREATED:20230824T174949Z
LAST-MODIFIED:20240229T104238Z
UID:10001312-1663758000-1663761600@cmsa.fas.harvard.edu
SUMMARY:Limit and potential of adaptive immunity
DESCRIPTION:Active Matter Seminar\n\nSpeaker: Shenshen Wang\, UCLA\n\n\nTitle:  Limit and potential of adaptive immunity\n\nAbstract: The adaptive immune system is able to learn from past experiences to better fit an\nunforeseen future. This is made possible by a diverse and dynamic repertoire of cells\nexpressing unique antigen receptors and capable of rapid Darwinian evolution within an\nindividual. However\, naturally occurring immune responses exhibit limits in efficacy\,\nspeed and capacity to adapt to novel challenges. In this talk\, I will discuss theoretical\nframeworks we developed to (1) explore functional impacts of non-equilibrium antigen\nrecognition\, and (2) identify conditions under which natural selection acting local in time\ncan find adaptable solutions favorable in the long run\, through exploiting environmental\nvariations and functional constraints.
URL:https://cmsa.fas.harvard.edu/event/title-tba/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-09.21.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220224T130000
DTEND;TZID=America/New_York:20220224T143000
DTSTAMP:20260405T140106
CREATED:20230824T172910Z
LAST-MODIFIED:20240213T111913Z
UID:10001308-1645707600-1645713000@cmsa.fas.harvard.edu
SUMMARY:Taming Active Matter: from ordered topological defects to autonomous shells
DESCRIPTION:Abstract: The spontaneous emergence of collective flows is a generic property of active fluids and often leads to chaotic flow patterns characterized by swirls\, jets\, and topological\ndisclinations in their orientation field. I will first discuss two examples of these collective features helping us understand biological processes: (i) to explain the tortoise & hare story in bacterial competition: how motility of Pseudomonas aeruginosa bacteria leads to a slower invasion of bacteria colonies\, which are individually faster\, and\n(ii) how self-propelled defects lead to finding an unanticipated mechanism for cell death. \nI will then discuss various strategies to tame\, otherwise chaotic\, active flows\, showing how hydrodynamic screening of active flows can act as a robust way of controlling and guiding active particles into dynamically ordered coherent structures. I will also explain how combining hydrodynamics with topological constraints can lead to further control of exotic morphologies of active shells.
URL:https://cmsa.fas.harvard.edu/event/taming-active-matter-from-ordered-topological-defects-to-autonomous-shells/
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-02.24.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220210T130000
DTEND;TZID=America/New_York:20220210T143000
DTSTAMP:20260405T140106
CREATED:20230824T172419Z
LAST-MODIFIED:20240304T083923Z
UID:10001307-1644498000-1644503400@cmsa.fas.harvard.edu
SUMMARY:Active Matter Controlling Epithelial Dynamics
DESCRIPTION:Abstract: My lab is interested in the active and adaptive materials that underlie control of cell shape.  This has centered around understanding force transmission and sensing within the actin cytoskeleton.  I will first review our current understanding of the types of active matter that can be constructed by actin polymers.  I will then turn to our recent experiments to understand how Cell shape changes in epithelial tissue.  I will describe the two sources of active stresses within these tissues\, one driven by the cell cycle and controlling cell-cell stresses and the other controlled by cell-matrix signaling controlling motility.  I will then briefly describe how we are using optogenetics to locally control active stresses to reveal adaptive and force-sensitive mechanics of the cytoskeletal machinery. Hopefully\, I will convince you that recent experimental and theoretical advances make this a very promising time to study this quite complicated form of active matter.
URL:https://cmsa.fas.harvard.edu/event/active-matter-controlling-epithelial-dynamics/
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-02.10.22-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220127T130000
DTEND;TZID=America/New_York:20220127T143000
DTSTAMP:20260405T140106
CREATED:20230824T171841Z
LAST-MODIFIED:20240304T083455Z
UID:10001306-1643288400-1643293800@cmsa.fas.harvard.edu
SUMMARY:Learning to School in the presence of hydrodynamic interactions
DESCRIPTION:Abstract: Fluids pervade complex systems\, ranging from fish schools\, to bacterial colonies and nanoparticles in drug delivery. Despite its importance\, little is known about the role of fluid mechanics in such applications. Is schooling the result of vortex dynamics synthesized by individual fish wakes or the result of behavioral traits? Is fish schooling energetically favorable?  I will present multifidelity computational studies of collective swimming in 2D and 3D flows. Our studies demonstrate that classical models of collective swimming (like the Reynolds model) fail to maintain coherence in the presence of long-range hydrodynamic interactions. We demonstrate in turn that collective swimming can be achieved through reinforcement learning. We extend these studies to 2D and 3D viscous flows governed by the Navier Stokes equations. We examine various hydrodynamic benefits with a progressive increase of the school size and demonstrate the importance of controlling the vorticity field generated by up to 300 synchronized swimmers.
URL:https://cmsa.fas.harvard.edu/event/learning-to-school-in-the-presence-of-hydrodynamic-interactions/
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Active-Matter-Seminar-01.27.2022-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211202T131500
DTEND;TZID=America/New_York:20211202T143000
DTSTAMP:20260405T140106
CREATED:20240213T113157Z
LAST-MODIFIED:20240304T084850Z
UID:10002504-1638450900-1638455400@cmsa.fas.harvard.edu
SUMMARY:Hydrodynamics and multi-scale order in confluent epithelia
DESCRIPTION:Abstract: In this talk I will review our ongoing theoretical and experimental efforts toward deciphering the hydrodynamic behavior of confluent epithelia. The ability of epithelial cells to collectively flow lies at the heart of a myriad of processes that are instrumental for life\, such as embryonic morphogenesis and wound healing\, but also of life-threatening conditions\, such as metastatic cancer. Understanding the physical origin of these mechanisms requires going beyond the current hydrodynamic theories of complex fluids and introducing a new theoretical framework\, able to account for biomechanical activity as well as for scale-dependent liquid crystalline order.
URL:https://cmsa.fas.harvard.edu/event/hydrodynamics-and-multi-scale-order-in-confluent-epithelia/
CATEGORIES:Active Matter Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211111T130000
DTEND;TZID=America/New_York:20211111T143000
DTSTAMP:20260405T140106
CREATED:20240213T112818Z
LAST-MODIFIED:20240304T084803Z
UID:10002501-1636635600-1636641000@cmsa.fas.harvard.edu
SUMMARY:Nonreciprocal matter: living chiral crystals
DESCRIPTION:Abstract: Active crystals are highly ordered structures that emerge from the nonequilibrium self-organization of motile objects\, and have been widely studied in synthetic and bacterial active matter. In this talk\, I will describe how swimming sea star embryos spontaneously assemble into chiral crystals that span thousands of spinning organisms and persist for tens of hours. Combining experiment\, hydrodynamic theory\, and simulations\, we demonstrate that the formation\, dynamics\, and dissolution of these living crystals are controlled by the natural development of the embryos. Remarkably\, due to nonreciprocal force and torque exchange between the embryos\, the living chiral crystals exhibit self-sustained oscillations with dynamic signatures recently predicted to emerge in materials with odd elasticity.
URL:https://cmsa.fas.harvard.edu/event/nonreciprocal-matter-living-chiral-crystals/
CATEGORIES:Active Matter Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211028T130000
DTEND;TZID=America/New_York:20211028T143000
DTSTAMP:20260405T140106
CREATED:20240213T112644Z
LAST-MODIFIED:20240304T084647Z
UID:10002498-1635426000-1635431400@cmsa.fas.harvard.edu
SUMMARY:Drivers of Morphological Complexity
DESCRIPTION:Abstract: During development\, organisms interact with their natural habitats while undergoing morphological changes\, yet we know little about how the interplay between developing systems and their environments impacts animal morphogenesis. Cnidaria\, a basal animal lineage that includes sea anemones\, corals\, hydras\, and jellyfish\, offers unique insight into the development and evolution of morphological complexity.  In my talk\, I will introduce our research on “ethology of morphogenesis\,” a novel concept that links the behavior of organisms to the development of their size and shape at both cellular and biophysical levels\, opening new perspectives about the design principle of soft-bodied animals. In addition\, I will discuss a fascinating feature of cnidarian biology. For humans\, our genetic code determines that we will grow two arms and two legs. The same fate is true for all mammals. Similarly\, the number of fins of a fish or legs and wings of an insect is embedded in their genetic code. I will describe how sea anemones defy this rule. \nReferences\nAnniek Stokkermans\, Aditi Chakrabarti\, Ling Wang\, Prachiti Moghe\, Kaushikaram Subramanian\, Petrus Steenbergen\, Gregor Mönke\, Takashi Hiiragi\, Robert Prevedel\, L. Mahadevan\, and Aissam Ikmi. Ethology of morphogenesis reveals the design principles of cnidarian size and shape development. bioRxiv 2021.08.19.456976 \nIkmi A\, Steenbergen P\, Anzo M\, McMullen M\, Stokkermans M\, Ellington L\, and Gibson M (2020). Feeding-dependent tentacle development in the sea anemone Nematostella vectensis. Nature communications\, Sept 02; 11:4399 \nHe S\, Del Viso F\, Chen C\, Ikmi A\, Kroesen A\, Gibson MC (2018). An axial Hox code controls tissue segmentation and body patterning in Nematostella vectensis. Science\, Vol. 361\, Issue 6409\, pp. 1377-1380.\nIkmi A\, McKinney SA\, Delventhal KM\, Gibson MC (2014). TALEN and CRISPR/Cas9 mediated genome editing in the early-branching metazoan Nematostella vectensis. Nature communications. Nov 24; 5:5486.
URL:https://cmsa.fas.harvard.edu/event/drivers-of-morphological-complexity/
CATEGORIES:Active Matter Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211014T130000
DTEND;TZID=America/New_York:20211014T143000
DTSTAMP:20260405T140106
CREATED:20240213T113426Z
LAST-MODIFIED:20240304T084942Z
UID:10002506-1634216400-1634221800@cmsa.fas.harvard.edu
SUMMARY:Stochastic PDE as scaling limits of interacting particle systems
DESCRIPTION:Abstract: Interacting particle models are often employed to gain understanding of the emergence of macroscopic phenomena from microscopic laws of nature. These individual-based models capture fine details\, including randomness and discreteness of individuals\, that are not considered in continuum models such as partial differential equations (PDE) and integral-differential equations. The challenge is how to simultaneously retain key information in microscopic models as well as efficiency and robustness of macroscopic models. In this talk\, I will illustrate how this challenge can be overcome by elucidating the probabilistic connections between models of different levels of detail. These connections explain how stochastic partial differential equations (SPDE) arise naturally from particle models. \nI will also present some novel scaling limits including SPDE on graphs and coupled SPDE. These SPDE not only interpolate between particle models and PDE\, but also quantify the source and the order of magnitude of stochasticity. Scaling limit theorems and duality formulas are obtained for these SPDE\, which connect phenomena across scales and offer insights about the genealogies and the time-asymptotic properties of the underlying population dynamics.
URL:https://cmsa.fas.harvard.edu/event/stochastic-pde-as-scaling-limits-of-interacting-particle-systems/
CATEGORIES:Active Matter Seminar
END:VEVENT
END:VCALENDAR