Seminars this semester


   Series:


Sep 24 Thu Abhishek Rajhans (Inter-University Center for Astronomy and Astrophysics (IUCAA), Pune, India) European Solar Physics Online Seminars (ESPOS)
10:00 https://zoom.us/j/165498165 Forward modelling and energetics of Hi-C brightenings
 
  Abstract:
The Solar coronal heating problem remains a persistent challenge in astrophysics. Parker postulated back in 1988 that the heating of corona should be dominated by small energy dissipation events, referred to as nanoflares. However, there have not yet been any confirmed observations of individual nanoflares. Hi-C reported unique bright points with energies ranging between log[E(ergs)] = 24-25. Those brightenings were also identified in AIA passbands. Here, I will describe 0-D hydrodynamical simulations to forward model these tiny brightenings, study their energetics, and discuss possible implications for coronal heating.
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Sep 24 Thu Abhishek Rajhans (Inter-University Centre for Astronomy and Astrophysics, IUCAA (IN)) SP2RC/ESPOS
11:00 https://zoom.us/j/165498165 Forward modelling and energetics of Hi-C brightenings
 
  Abstract:
The Solar coronal heating problem remains a persistent challenge in astrophysics. Parker postulated back in 1988 that the heating of corona should be dominated by small energy dissipation events, referred to as nanoflares. However, there have not yet been any confirmed observations of individual nanoflares. Hi-C reported unique bright points with energies ranging between log[E(ergs)] = 24-25. Those brightenings were also identified in AIA passbands. Here, I will describe 0-D hydrodynamical simulations to forward model these tiny brightenings, study their energetics, and discuss possible implications for coronal heating.
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Sep 30 Wed Visakan Balakumar (Sheffield) Cosmology, Relativity and Gravitation
15:00 Blackboard Collaborate Quantum superradiance on static black hole space-times
 
  Abstract:
We study the quantum analogue of the classical process of superradiance for a massless charged scalar field on a charged black hole space-time. We show that an “in” vacuum state, which is devoid of particles at past null infinity, contains an outgoing flux of particles at future null infinity. This radiation is emitted in the superradiant modes only, and is nonthermal in nature.
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Oct 1 Thu Rekha Jain (Sheffield) Plasma Dynamics Group
16:00 https://meet.google.com/chc-nxsh-xcz
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Oct 2 Fri SP2RC seminar
13:00 LT 11
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Oct 7 Wed Katy Clough (Oxford) Cosmology, Relativity and Gravitation
15:00 remote TBA
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Oct 8 Thu (Physikalisch-Meteorologisches Observatorium Davos, PMOD/WRC (CH)) SP2RC/ESPOS
00:00
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Oct 14 Wed Indira Chatterji (University of Nice) Pure Maths Colloquium
14:00 online Group ring conjectures and relative hyperbolicity
 
  Abstract:
The idempotent conjecture is that there should be no idempotent in the group ring of a torsion-free group. I will discuss this conjecture, as well as associated conjectures in some geometric context, and will use them as an excuse to discuss hyperbolicity and introduce relative hyperbolicity, a context in which some of these conjectures are still open.
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Oct 14 Wed Jose Cembranos (Madrid) Cosmology, Relativity and Gravitation
15:00 remote TBA
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Oct 15 Thu SP2RC seminar
10:00 LT 11 UK Solar Online Seminar Series (UK-SOSS) monthly seminar:
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Oct 15 Thu George Haller (ETH Zurich (Switzerland)) Plasma Dynamics Group
13:00 https://meet.google.com/zxj-ofaw-guc Objective material barriers to the transport of momentum and vorticity
 
  Abstract:
I discuss a recent theory for material surfaces that maximally inhibit the diffusive transport of a dynamically active (i.e., velocity-dependent) vector field, such as the linear momentum, the angular momentum or the vorticity, in three-dimensional unsteady flows. These diffusion barriers provide physics-based, observer-independent boundaries of dynamically active coherent structures. Instantaneous limits of these Lagrangian diffusion barriers mark objective Eulerian barriers to short-term active transport. I show how active diffusion barriers can be identified with active versions of Lagrangian coherent structure (LCS) diagnostics. In comparison to their passive counterparts, however, active LCS diagnostics require no significant fluid particle separation and hence provide substantially higher-resolved Lagrangian and Eulerian coherent structure boundaries from shorter velocity data sets. I illustrate these results on two-dimensional turbulence and three-dimensional wall-bounded turbulence.
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Oct 21 Wed Atsushi Higuchi (York) Cosmology, Relativity and Gravitation
15:00 remote TBA
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Oct 22 Thu (University of Coimbra (PT)) SP2RC/ESPOS
00:00
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Oct 28 Wed Clara Loeh (University of Regensburg) Pure Maths Colloquium
14:00 J11
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Oct 28 Wed Harry Desmond (Oxford) Cosmology, Relativity and Gravitation
15:00 remote TBA
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Nov 4 Wed Ulrich Pennig (University of Cardiff) Pure Maths Colloquium
14:00 J11
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Nov 5 Thu (Institut d’Astrophysique Spatiale, IAS (FR)) SP2RC/ESPOS
00:00
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Nov 11 Wed Sira Gratz (University of Glasgow) Pure Maths Colloquium
14:00 J11
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Nov 11 Wed Lisa Glaser (Vienna) Cosmology, Relativity and Gravitation
15:00 remote TBA
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Nov 12 Thu SP2RC seminar
10:00 LT 11 UK Solar Online Seminar Series (UK-SOSS) monthly seminar:
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Nov 12 Thu Francisco Guzman (Universidad Michoacana de San Nicolas de Hidalgo, Mexico) Plasma Dynamics Group
16:00 Remote TBA
 
  Abstract:
TBA
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Nov 18 Wed Andreagiovanni Reina (CS, Sheffield)
14:00 https://meet.google.com/??? Collective Decision Making: From Bees to Robots via Multiscale Modelling
 
  Abstract:
I will give an overview of my studies on modelling and simulating collective decision making in distributed systems. Such systems, found in biology, sociology, and engineering, are composed of a large number of interacting individuals that coordinate in order to reach a consensus. The main phases of the collective decision making process consist of identifying the available options, estimating their quality, and selecting the best option or any of them. I will present the main results of my research in understanding and designing each of these phases. Collective systems are inherently difficult to analyse as the stochastic nonlinear interactions between individuals can give rise to complex emergent dynamics. Therefore, I employ a collection of advanced techniques, commonly defined as multiscale modelling. Relying on a set of methods, rather than a single one, gives the benefit of having complementary techniques addressing one another's limitations. In fact, through multiscale modelling, it is possible to analyse the systems at various levels of complexity and detail, from macroscopic group-level dynamics to microscopic individual-level behaviour, and from noise-free deterministic models to stochastic spatial descriptions. I finally shed a light on the recently developed opensource software for automated multiscale modelling. This software, called MuMoT, can also be a useful resource for remote teaching. For more info on MuMoT see (Marshall et al. PlosOne 2019) or MuMoT live notebook (https://mumot.readthedocs.io/). Bio: Dr Andreagiovanni Reina is a Research Fellow in Collective Robotics at the University of Sheffield, UK. He is currently working on the DiODe project (Distributed Algorithms for Optimal Decision-Making) led by Prof. James Marshall, and is the Principal Investigator of the Swarm Awareness project (https://swarmawareness.group.shef.ac.uk/). Andreagiovanni is the researcher responsible for more than 900 Kilobot robots and the related Augmented Reality for Kilobot (ARK) infrastructure at Sheffield Robotics. He holds a PhD in applied sciences from IRIDIA (Marco Dorigo's AI-Laboratory) of the Université Libre de Bruxelles, Belgium, and an M.Sc. in computer engineering from Politecnico di Milano, Italy. He has been a researcher in five European projects on distributed robotic systems since 2009. In December 2020, he plans to return to Brussels with an FNRS Fellowship on modelling heterogeneity in decentralised consensus. Full info at http://areina.staff.shef.ac.uk.
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Nov 18 Wed Sara Arias de Reyna (University of Seville) Pure Maths Colloquium
14:00 J11
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Nov 18 Wed Andreagiovanni Reina (CS, Sheffield) Applied Mathematics Colloquium
14:00 https://meet.google.com//kkc-jmys-uwa Collective Decision Making: From Bees to Robots via Multiscale Modelling
 
  Abstract:
Abstract: I will give an overview of my studies on modelling and simulating collective decision making in distributed systems. Such systems, found in biology, sociology, and engineering, are composed of a large number of interacting individuals that coordinate in order to reach a consensus. The main phases of the collective decision making process consist of identifying the available options, estimating their quality, and selecting the best option or any of them. I will present the main results of my research in understanding and designing each of these phases. Collective systems are inherently difficult to analyse as the stochastic nonlinear interactions between individuals can give rise to complex emergent dynamics. Therefore, I employ a collection of advanced techniques, commonly defined as multiscale modelling. Relying on a set of methods, rather than a single one, gives the benefit of having complementary techniques addressing one another's limitations. In fact, through multiscale modelling, it is possible to analyse the systems at various levels of complexity and detail, from macroscopic group-level dynamics to microscopic individual-level behaviour, and from noise-free deterministic models to stochastic spatial descriptions. I finally shed a light on the recently developed opensource software for automated multiscale modelling. This software, called MuMoT, can also be a useful resource for remote teaching. For more info on MuMoT see (Marshall et al. PlosOne 2019) or MuMoT live notebook (https://mumot.readthedocs.io/). Bio: Dr Andreagiovanni Reina is a Research Fellow in Collective Robotics at the University of Sheffield, UK. He is currently working on the DiODe project (Distributed Algorithms for Optimal Decision-Making) led by Prof. James Marshall, and is the Principal Investigator of the Swarm Awareness project (https://swarmawareness.group.shef.ac.uk/). Andreagiovanni is the researcher responsible for more than 900 Kilobot robots and the related Augmented Reality for Kilobot (ARK) infrastructure at Sheffield Robotics. He holds a PhD in applied sciences from IRIDIA (Marco Dorigo's AI-Laboratory) of the Université Libre de Bruxelles, Belgium, and an M.Sc. in computer engineering from Politecnico di Milano, Italy. He has been a researcher in five European projects on distributed robotic systems since 2009. In December 2020, he plans to return to Brussels with an FNRS Fellowship on modelling heterogeneity in decentralised consensus. Full info at http://areina.staff.shef.ac.uk.
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Nov 19 Thu (Queen’s University Belfast, Astrophysics Research Centre (UK)) SP2RC/ESPOS
00:00
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Nov 25 Wed Ailsa Keating (University of Cambridge) Pure Maths Colloquium
14:00 J11
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Dec 2 Wed Yemon Choi (University of Lancaster) Pure Maths Colloquium
14:00 J11
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Dec 3 Thu (Leibniz Institute for Astrophysics Potsdam (DE)) SP2RC/ESPOS
00:00
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Dec 9 Wed Kathryn Hess (École Polytechnique Fédérale de Lausanne) Pure Maths Colloquium
14:00 J11
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Dec 10 Thu SP2RC seminar
10:00 LT 11 UK Solar Online Seminar Series (UK-SOSS) monthly seminar:
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Dec 10 Thu Richard Morton (University of Northumbria) Plasma Dynamics Group
16:00 TBA
 
  Abstract:
TBA
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Dec 16 Wed Marina Illiopoulou (University of Kent) Pure Maths Colloquium
14:00 J11
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Dec 17 Thu (University of Sheffield, Solar Physics and Space Plasma Research Centre (UK)) SP2RC/ESPOS
00:00
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Jan 21 Thu SP2RC seminar
13:00 LT 11 UK Solar Online Seminar Series (UK-SOSS) monthly seminar:
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