Events List for the Academic Year

Event Time: Friday, December 9, 2022 | 1:30 pm - 3:30 pm
Event Location:
Henn 318
Add to Calendar 2022-12-09T13:30:00 2022-12-09T15:30:00 Biophysics of disease and evolution: Molecules to Organisms Event Information: This thesis describes applications of computer simulation and bioinformatics techniques in conjunction with experiments to understand various biological systems.   In Chapter 2, we used molecular dynamics simulations to uncover the structural details of an experimentally observed interaction between the ALS-associated protein superoxide dismutase 1 (SOD1), and TNF receptor-associated factor 6. Residues present in their heterodimer binding interface were predicted through unbiased and metadynamics simulations and tested in cultured cells.   In Chapter 3, we used a quick computational scan to identify two de novo mutations of SOD1, A89R and K128N that were expected to be destabilizing and stabilizing respectively. Expression in cell cultures and zebrafish confirmed that A89R produces pathologies similar to the ALS-associated mutant A4V, and that K128N is WT-like. Interestingly, unlike WT-SOD1, K128N rescued the aberrant phenotype of zebrafish motor neurons when coinjected with A4V-SOD1. To explain this, we used computational alchemy to calculate heterodimerization free energies for A4V-SOD1 with WT-SOD1 and K128N-SOD1, but could not confirm a "heterodimer-rescue" mechanism.   In Chapter 4, we studied the conformational landscape of the SARS-CoV-2 spike protein. The conserved residues 980--990, normally buried under the receptor binding domain, have been reported to be transiently accessible to antibodies. Through umbrella sampling simulations we found that direct exposure of the epitope through dynamic motions is not a likely mechanism for this accessibility. Further, glycans play an important role in preventing such dynamics. During its normal function, this epitope undergoes a large-scale conformational change from a bent to an extended state. To aid development of a vaccine antigen containing the conserved fragment, we studied the free energy cost of this change and found that a bent pre-fusion-like conformation is preferred.   Moving on from protein studies, in Chapter 5 we were interested in the biophysics of genome organization, and its evolution in early ancestors of all animals. The basal metazoan Mnemiopsis leidyi is well-suited for such studies but has not been standardized as a model organism. We developed protocols for laboratory culture of this organism, and obtained a highly contiguous reference genome for an inbred lineage. Event Location: Henn 318
Event Time: Friday, December 9, 2022 | 8:30 am - 10:30 am
Event Location:
https://ubc.zoom.us/j/62811600818?pwd=WlJyS09SQ0gva3EwZ1N3dmNDdmZlQT09 Passcode: 459642
Add to Calendar 2022-12-09T08:30:00 2022-12-09T10:30:00 Magnetic resonance imaging to measure myelin: orientation dependence and application to spinal cord injury Event Information: Myelin, the lipid-rich sheath which wraps around axons, has complex and unique physical and chemical properties which can be used to produce magnetic resonance imaging (MRI) contrast. Developing MRI to quantitatively measure myelin is vital for monitoring the brain and spinal cord in health and disease. This thesis explores four MRI techniques sensitive to myelin; myelin water imaging (MWI), magnetisation transfer (MT), inhomogeneous magnetisation transfer (ihMT) and diffusion imaging. First, these metrics were measured in regions throughout the healthy adult and pediatric brain. Reproducibility, dynamic range and correlations between metrics were investigated. Healthy adult and pediatric atlases of the metrics were made publicly available for other neuroimaging researchers. Next, the orientation dependence of MWI, MT and ihMT was quantified. White matter is anisotropic, consisting of fiber bundles which vary in angle to the MRI main magnetic field. This can affect MRI metrics through the susceptibility of lipid-rich myelin, anisotropic vasculature, iron content, dipole-dipole and magic angle effects. We found that the orientation dependence curve for each metric varied between brain regions, suggesting that microstructural parameters other than fibre angle are affecting the orientation dependence. Then, we investigated the orientation dependence of ihMT in more detail, using a phospholipid bilayer sample rotated in a nuclear magnetic resonance (NMR) spectrometer to measure the variation with angle of the breadth of the lipid spectrum and dipolar order relaxation time. We found that the lipid linewidth had a greater effect on ihMT than the dipolar order relaxation time under our experimental conditions. Finally, ex vivo human spinal cord injury (SCI) tissue from the International SCI Biobank was scanned at 7 Tesla to obtain MWI, ihMT and diffusion. This tissue then underwent histological staining for myelin lipids and inflammatory cells. We performed correlations between the MRI metrics and the digitised histological staining to validate the metrics’ specificity to myelin and sensitivity to inflammation processes. We measured the MRI metrics in motor and sensory white matter tracts along the cord, which provided a first glimpse into the possible utility of these techniques as biomarkers to assess the impact of SCI on myelin and axons in vivo.  Event Location: https://ubc.zoom.us/j/62811600818?pwd=WlJyS09SQ0gva3EwZ1N3dmNDdmZlQT09 Passcode: 459642
Event Time: Thursday, December 8, 2022 | 4:00 pm - 5:00 pm
Event Location:
HEBB 114
Add to Calendar 2022-12-08T16:00:00 2022-12-08T17:00:00 Use of Indigenous Elements in Teaching Mathematics and Science Event Information:   Abstract: This presentation is based on materials collected within my research and community-based projects at the First Nations University of Canada and targets three groups of audience: learners, educators and researchers. The materials have been created in three formats: publications, Power Point Presentations and Videos. My intention is to address the importance, doability and advantage of the holistic way of teaching the Science and Mathematics in an example of the integration of modern Science and Indigenous Knowledge elements. Bio: Dr. Sardarli joined the First Nations University of Canada in 2007. He led a number of community-based projects. Dr. Sardarli uses Indigenous elements in his teaching. He co-authored the first Cree Dictionary of Mathematical with elements of Indigenous Art. In 2008, Dr. Sardarli initiated a nationwide annual Wiseman Mathematics Contest. He coordinated the research project on mathematical modeling of water quality using Indigenous knowledge. Dr. Sardarli’s projects have been supported by agencies, such as NSERC, SSHRC, Health Canada, and Canadian Heritage. He received The Recognition Event Awards of The Regional Centre of Expertise (Saskatchewan) for his innovative Indigenous community-based projects   Outline:  It is remarkable that the word "Science" that we, educators use as a title for the group of subjects (Physics, Biology, Chemistry, etc.) taught in academia, is translated into many languages (Arabian, Ukrainian, Turkish ...) as "Knowledge", giving the meaning of gaining and analysis of integrated information about both, Nature and Community. This is not just a linguistic nuance. I try to bring elements of the Indigenous Knowledge and Art to the teaching of my post-secondary Mathematics and Science courses in order to add this missing piece to the puzzle, combining the so-called "Western" and Indigenous Knowledge. My view of this integration is very close to the "Etuaptmumk" - Two-Eyed Seeing principle explained by Elder Albert Marshall, which refers to "learning to see from one eye with the strengths of Indigenous knowledge and ways of knowing, and from the other eye with the strengths of Western knowledge and ways of knowing ... and learning to use both these eyes together, for the benefit of all". In collaboration with my colleagues from the First Nations University of Canada and the University of Regina, I have developed examples with Indigenous elements for Physics, Mathematics and Statistics courses of our universities. Within my research and community-based projects I interviewed Indigenous Elders and Knowledge Keepers in order to collect the information for these examples. The examples are included in the textbooks that I co-authored and course materials offered by the First Nations University of Canada and the University of Regina. These projects were supported by The Natural Sciences and Engineering Research Council of Canada (NSERC), Health Canada, Heritage Canada, First Nations University of Canada and the University of Regina. Modern technologies allow us to incorporate the original interviews into the teaching materials in various media formats. Projects: 1. Wiseman Mathematics Contest I initiated the Wiseman Mathematics Contest was in 2008 at the First Nations University of Canada. The start-up of the project was supported by The Natural Sciences and Engineering Research Council of Canada within the PromoScience program. Since then, thousands of First Nations students from across Canada in grades 4, 5, and 6 across Canada have participated. The purpose of the Contest is to motivate young students in First Nations schools in Saskatchewan and other provinces to learn Mathematics in a competitive environment. The Wiseman Mathematics Contest meets the needs of Mathematics teachers in First Nations Schools who want to assess their students' problem-solving skills in a competitive environment. Along with the contests, First Nations University also develops and delivers preparatory materials. Mathematics teachers prepare their students for the contest using these materials, but can also use the materials to immerse the students in alternative problem-solving, expanding on curriculum. Many teachers use these materials for extracurricular activities. Students participate in the project voluntarily. The contest provides the opportunity to work on non-traditional problems in a non-mandatory but competitive environment, which is atypical for Western schools. In 2016, the Regional Centre of Expertise (Saskatchewan) on Education for Sustainable Development Recognition Program acknowledged the Wiseman Mathematics Contest as an innovative project. It noted that the project has helped increase the capacity for sustainable development in the Saskatchewan region and contributed to the advancement of the UNESCO Global Action Programme on Education for Sustainable Development. 2. Cree Dictionary of Mathematical Terms In 2015 – 2021, we developed the first explanatory Cree Dictionary of Mathematical Terms in paper (Willie Ermine, Arzu Sardarli, Ida Swan) and online (Arzu Sardarli, Ida Swan) formats. The project was supported by the First Nations University of Canada and the University of Regina. The Dictionary was reviewed by Elders George McLeod and Jerry Saddleback, Indigenous academics Solomon Ratt and Lionel Peyachew, educators Nelson Benjamin Merasty and Steven Swan. The Indigenous artist Larissa Kitchemonia participated in developing visual examples. This project was recognized by Lyle Benko Future Generations Award of the Saskatchewan Regional Centre of Expertise. Research projects I used some findings of my research projects to develop examples with Indigenous elements for my university courses. 3. Research project "Developing Mathematical Model of Water Quality Dynamics using Indigenous Knowledge." This project was conducted in collaboration with the Kahkewistahaw and Peepeekisis First Nations communities. Within the project, we interviewed Indigenous Elders and specified criteria to evaluate the water quality. Community members were asked to evaluate water quality in their communities based on the determined criteria. Using the statistical analysis of the collected data, we developed a mathematical model of the water quality dynamics using the Indigenous way of evaluating the water quality. 4. Research project " Studies of physical parameters of Indigenous artefacts; collecting and preserving the relating oral stories." This project was conducted by scholars from the First Nations University of Canada, Royal Saskatchewan Museum, University of Regina and University of Saskatchewan in collaboration with Sturgeon Lake and Pelican Narrows First Nations communities in Canada. The objectives of the project were (i) to develop a research ethics protocol for collecting, studying and preserving Indigenous artifacts; (ii) to determine physical parameters of artifacts from communities and Royal Saskatchewan Museum collections; (iii) to collect oral stories in communities. Within the project, we managed consultations with Elders and Indigenous Knowledge Keepers. Two workshops were organized in the communities. Indigenous students were trained to work in the communities. The laboratory measurements were carried out at the Scanning Electron Microscope Laboratory of the University of Alberta, the Saskatchewan Isotope Laboratory of the University of Saskatchewan and the André E. Lalonde Accelerator Mass Spectrometry Laboratory of the University of Ottawa. We analyzed the data obtained from the measurements of physical parameters of artifacts collected in these communities and selected from the Royal Saskatchewan Museum collections. The purpose of the statistical analysis was to determine the similarities of artifacts with respect to their chemical compositions. REFERENCES: Books W. Ermine, A. Sardarli, I. Swan, "Cree Dictionary of Mathematical Terms for Elementary Classes", 170 p, ISBN-13: 978-0-7731-0770-0, University of Regina, 2017 A. Sardarli, I. Swan, "Cree Dictionary of Mathematical Terms with Visual Examples, Online ISBN-13: 978-0-7731-0779-3, University of Regina, 2022 URL: https://opentextbooks.uregina.ca/creemathdictionary/ A. Sardarli, "Studies of Physical Parameters of Indigenous Artifacts. Collecting and preserving the relating oral stories", 160 p, Print ISBN-13: 978-0-7731-0767-0, Online ISBN-13: 978-0-7731-0769-4, University of Regina, 2021 URL: http://indigenous-artifacts.ca/brochure/ A. Sardarli, E. Siegfried, S. Wall, “Studies of Physical Parameters of Indigenous Artifacts. Collecting and preserving the relating oral stories. Catalogue”, 86 p, Print ISBN-13: 978-0-7731-0765-6, Online ISBN-13: 978-0-7731-0766-3, University of Regina, 2021 URL: http://indigenous-artifacts.ca/catalogue/ Articles "Two-Eyed Seeing", Mi'kmaw Elder Albert Marshall URL: http://www.integrativescience.ca/Principles/TwoEyedSeeing/ A. Sardarli, Use of Indigenous Knowledge in Modeling the Water Quality Dynamics in Peepeekisis and Kahkewistahaw First Nations Communities, Pimatiswin: A Journal of Aboriginal and Indigenous Community Health 11(1), 2013, 55-63 URL: https://journalindigenouswellbeing.co.nz/use-of-indigenous-knowledge-in-modeling-the-water-quality-dynamics-in-peepeekisis-and-kahkewistahaw-first-nations-communities/ A. Sardarli, S. Pete, T. Ngamkham, S. Suraphee, A. Volodin, The Determinants of Annual Income in Aboriginal and Non-Aboriginal Communities: Comparative Statistical Analysis, Thailand Statistician, 17(2), 2019, 235-241 URL: https://ph02.tci-thaijo.org/index.php/thaistat/article/view/202300/141174 A. Sardarli, A. Volodin, Kh. Osmanli, E. Siegfried, Statistical Analysis of Physical Parameters of Indigenous Artifacts, Lobachevskii Journal of Mathematics, 42 (13), 2021, 3224-3229 URL: https://link.springer.com/article/10.1134/S1995080222010188 Project Websites Wiseman Mathematics Contest | URL: https://www.facebook.com/WisemanContest Studies of Physical Parameters of Indigenous Artifacts. Collecting and preserving the relating oral stories | URL: http://indigenous-artifacts.ca/         Event Location: HEBB 114
Event Time: Monday, December 5, 2022 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
Add to Calendar 2022-12-05T15:00:00 2022-12-05T16:00:00 A Revolution in Stellar Astrophysics, and the Remaining Challenges Event Information: Abstract: ESA's Gaia mission has provided distances to around 1.5 billion stars and revolutionized stellar astrophysics. Gaia has finally revealed the population of faint white dwarf stars in the solar neighborhood. We use this dataset to answer fundamental questions about the nature of white dwarfs, including their mass distribution, cooling physics (crystallization), and ultracool white dwarfs. I will highlight the current challenges in the physics of white dwarf stars and our efforts to solve them. Bio: Mukremin Kilic is an associate professor in the Department of Physics & Astronomy at the University of Oklahoma.   Event Location: HENN 318
Event Time: Friday, December 2, 2022 | 1:30 pm - 3:30 pm
Event Location:
Hennings 318
Add to Calendar 2022-12-02T13:30:00 2022-12-02T15:30:00 Computational Modeling and Design of Oligomer Selective Vaccine Candidates for Parkinson’s and Alzheimer’s Disease Event Information: Protein aggregation-related diseases, in particular neurodegenerative diseases, are characterized by the aberrant perturbation of the underlying protein conformational ensemble. Effectively presenting epitopes using vaccines, to raise conformationally selective antibodies, is a central problem in treating neurodegenerative diseases. Parkinson’s and Alzheimer’s disease, which pathogenesis has been attributed to aberrant aggregates of α-synuclein and tau protein, respectively, are the two most common neurodegenerative diseases. Designing conformationally selective vaccines in silico often requires: 1.) an effective epitope scaffolding strategy that selectively targets pathologic aggregates known as oligomers while sparing the more abundant healthy monomers, with both the oligomeric and the monomeric forms having essentially identical amino acid sequences, and 2.) efficient methods and software for quantitative comparison of large conformational ensembles, which are currently not readily available.    In this thesis, we apply various computational techniques including those based on information theory and principles of physics to address these two challenges. We computationally modeled and designed cyclic peptide and β-helix protein vaccines to best mimic toxic oligomeric conformational ensembles of α-synuclein and tau protein computationally-predicted epitopes, respectively. In both Parkinson’s and Alzheimer’s disease, our designed vaccines are predicted to be conformationally selective for toxic oligomers. Additionally, we developed a new generalized method for efficient representation and comparison of protein conformational ensembles. The method is up to 88 times faster while utilizing 48 times fewer computing cores than the readily available Encore software on a molecular dynamics-generated ensemble dataset.    The methods developed and results presented in this thesis will not only accelerate the process of in silico conformation-specific vaccine design for protein aggregation-related diseases but have potential applications to antibody drug discovery and development in pharmaceutical biotechnology. Event Location: Hennings 318
Event Time: Thursday, December 1, 2022 | 4:00 pm - 5:00 pm
Event Location:
HEBB 114
Add to Calendar 2022-12-01T16:00:00 2022-12-01T17:00:00 Nanoaperture Tweezers: From Single Proteins to Single Quantum Emitters Event Information:   Abstract: There is a new class of technologies emerging for observing unmodified proteins in action and at the single molecule level. This colloquium will give an introduction to our nanoaperture optical tweezer approach and overview the developments from other groups also working in the area. I will also review our work on using these nanoapertures to isolate single Erbium emitters in nanocrystals for single photon sources at fiber optic communication wavelengths, and to study resonant energy transfer between two perovskite quantum dots. Bio: Dr. Reuven Gordon is a Professor of Electrical and Computer Engineering at the University of Victoria and a recent Canada Research Chair in Nanoplasmonics. Dr. Gordon is an expert in nanoplasmonics: the interaction of light with metal surfaces at tiny scales. See Dr. Gordon's faculty webpage here: Reuven Gordon - University of Victoria (uvic.ca) See Dr. Gordon's Nanoplasmonics Research Group here: Home (uvic.ca)   Event Location: HEBB 114
Event Time: Thursday, December 1, 2022 | 10:00 am - 11:00 am
Event Location:
BRIM 311
Add to Calendar 2022-12-01T10:00:00 2022-12-01T11:00:00 CM Seminar: How Electron Hydrodynamics Can Eliminate the Landauer-Sharvin Resistance Event Information: Thomas Scaffidi - University of California Irvine Title: How Electron Hydrodynamics Can Eliminate the Landauer-Sharvin Resistance  Abstract: What is the ultimate limit of conductance of a metallic device of lateral size W? In the ballistic limit, the answer is the Landauer-Sharvin conductance, which is associated with an abrupt reduction of the number of conducting channels when going from the contacts to the device. However, the ballistic limit is not always the best-case scenario, since adding strong electron-electron scattering can take electrons to a viscous regime of transport for which "super-ballistic" flows were recently studied. In this talk, we will show that by a proper choice of geometry which resembles a "wormhole", it is possible to spread the Landauer-Sharvin resistance throughout the bulk of the system, allowing its complete elimination by electron hydrodynamics. This effect arises due to the interplay between geometry and strong electron-electron scattering, which allows for a net transfer of carriers from reflected to transmitted channels. Finally, we will discuss a recent experiment in a Corbino geometry which realizes one half of this "wormhole" geometry. Refs: Theory: Phys. Rev. Lett. 129, 157701 (2022) Experiment: Nature 609, 276–281 (2022) Event Location: BRIM 311
Event Time: Monday, November 28, 2022 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
Add to Calendar 2022-11-28T15:00:00 2022-11-28T16:00:00 What can high-redshift, infrared-luminous galaxies tell us about galaxy formation physics and cosmology? Event Information:   Abstract: Interstellar dust is pervasive throughout the Universe, and most light from young, massive stars is absorbed by dust and reradiated as thermal emission in the infrared. Submillimeter galaxies (SMGs), a class of very infrared-luminous distant galaxies, are some of the most extreme star-forming galaxies known, forming stars at rates hundreds or even thousands of times greater than our own Milky Way. I will review our understanding of this enigmatic population, which has challenged galaxy formation theories since their discovery in the late 1990s. I will highlight how the population provides novel constraints on galaxy formation physics, cosmology, and possibly even the nature of dark matter. I will also show how they serve as beacons of galaxy clusters in the process of formation. Bio: I am a theorist who works to answer a wide variety of pressing open questions regarding galaxy formation. I emphasize bridging the gap between theory and observations by predicting observables from hydrodynamical simulations of galaxies through dust radiative transfer. I also do more traditional ‘pure’ theoretical work, ranging from developing an analytic theory for how stellar feedback simultaneously regulates star formation and drives outflows to magnetohydrodynamic simulations of galaxy mergers to detailed comparisons of numerical hydrodynamical methods and 'sub-resolution' implementations of crucial physical processes that cannot currently be treated ab initio in galaxy formation simulations, such as black hole growth. I am currently an Associate Research Scientist at the Center for Computational Astrophysics, Flatiron Institute, which is funded by the Simons Foundation. Previously, I was a Moore Prize Postdoctoral Scholar in Theoretical Astrophysics at Caltech, where I primarily worked with Prof. Phil Hopkins. From December 2011 until July 2014, I was an independent postdoctoral scholar in Prof. Volker Springel’s group at the Heidelberg Institute for Theoretical Studies. In October 2011, I earned my PhD from Harvard; my supervisor was Prof. Lars Hernquist. Prior to starting at Harvard in September 2006, I spent a year in Cambridge, England, where I earned a Master of Advanced Study in Applied Mathematics and Theoretical Physics (with honors) for surviving Part III of the Mathematical Tripos. My undergrad years were spent at the University of Michigan, where I triple-majored in Astronomy & Astrophysics (highest honors), Physics, and Mathematics (high honors). I had the great fortune to start doing astrophysics research with Prof. Joel Bregman essentially as soon as I arrived at U of M, and I haven’t looked back since! For more information, please see Dr. Hayward's research website here.   Event Location: HENN 318
Event Time: Monday, November 28, 2022 | 11:00 am - 12:00 am
Event Location:
HENN 318
Add to Calendar 2022-11-28T11:00:00 2022-11-28T00:00:00 The future of gravitational wave detectors Event Information: TALK RECORDING AVAILABLE AT: https://drive.google.com/file/d/1is7783zB9tYQksLkmcAZ5E5NQu7mZvOP/view Abstract Just seven years after their first detection, gravitational waves (GWs) have revealed the first glimpses of a previously hidden dark Universe. Using the GW signature of distant compact-object collisions, we have discovered a new population of stellar remnants and unlocked new tests of general relativity, cosmology, and ultra-dense matter. How do we go further, and what might we learn when we do? I’ll discuss planned designs for future ground-based and space-based gravitational wave detectors, and the new science we will gain from detectors that can sense black hole collisions throughout cosmic time. Event Location: HENN 318
Event Time: Thursday, November 24, 2022 | 4:00 pm - 5:00 pm
Event Location:
HEBB 114
Add to Calendar 2022-11-24T16:00:00 2022-11-24T17:00:00 Accelerators as windows to the dark sector: the DarkLight experiment and the hunt for a new boson Event Information: Link to join remotely - look for today's date. The live stream will start at 4:00pm. Abstract: The nature of dark matter and its relationship to the Standard Model is one of the highest priority open questions in particle physics today. Accelerator-based experiments are a powerful tool in the search for dark matter and the new bosons that may mediate its interactions with the known particles. The DarkLight experiment will search for such a new boson with suppressed couplings to protons in an important uncovered low-mass range. DarkLight will be based at the TRIUMF electron linear accelerator and will pave the way for this unique machine to drive other future experiments.   Bio: Kate is an experimental particle physicist whose research focuses on searches for new particles. She was a part of the ATLAS collaboration for more than 10 years but is now focusing on the new DarkLight experiment at TRIUMF.  She got her BSc from the University of Victoria and her PhD from the University of Oxford. She worked as a postdoc first at Simon Fraser University and then at Duke University before beginning her current position as a TRIUMF research scientist. For more information on the DarkLight project, see this article: DarkLight: a new particle search at TRIUMF. Event Location: HEBB 114
Event Time: Thursday, November 24, 2022 | 10:00 am - 11:00 am
Event Location:
BRIM 311
Add to Calendar 2022-11-24T10:00:00 2022-11-24T11:00:00 CM Seminar: Long Ju - Electron Correlation and Coupling with Phonon in the Trilayer Graphene/hBN Moire Superlattice Event Information: Long Ju – MIT Physics Department  Title: Electron Correlation and Coupling with Phonon in the Trilayer Graphene/hBN Moire Superlattice Abstract: ABC-stacked trilayer graphene/hexagonal boron nitride moiré superlattice (TLG/hBN) has emerged as a playground for correlated electron physics. A spectroscopy study of this system is, however, challenging due to the device configuration. In this talk, I will introduce our recent efforts on FTIR photocurrent spectroscopy measurements of dual-gated TLG/hBN. We observed strong gate-tunable optical transitions that originated from the moire flat band. At half-filling of the valence flat band, a broad absorption peak emerges at ~18 meV, indicating direct optical excitation across an emerging Mott gap. Furthermore, I will talk about a unique moire-enabled interlayer electron-phonon coupling phenomenon in this system. The ZO phonon in hBN hybridizes with electron-hole excitations in trilayer graphene and appear as an asymmetric peak in the photocurrent spectrum. This Fano line-shaped peak evolves continuously as we tune the displacement field. I’ll talk about the implications of this phenomenon to engineering the physics of moire quantum matters. Bio: Long Ju joined the MIT Physics Department as an assistant professor in January 2019. He received his B.S. in Physics in 2009 from Tsinghua University, China, and his Ph.D. in Physics in 2015 from the University of California, Berkeley. He then moved to Cornell University, where he was a Kavli postdoctoral fellow until December 2018.   Event Location: BRIM 311
Event Time: Wednesday, November 23, 2022 | 3:00 pm - 5:00 pm
Event Location:
https://ubc.zoom.us/j/61408939131?pwd=cGxvZDU4Zi9oTmVySjg1RTN2T1E5QT09, Passcode: 524103
Add to Calendar 2022-11-23T15:00:00 2022-11-23T17:00:00 Radiative Capture and Decays in Ab Initio Nuclear Theory Event Information: Atomic nuclei exhibit many phenomena not limited to excited states, decays, reactions, and clustering. Nuclear processes control the evolution of stars and explain the abundances of chemical elements in the universe. Nuclear physics can be used to answer fundamental questions about underlying particle physics and cosmology, such as the symmetry between matter and antimatter or the nature of neutrinos. The discrepancy between theoretical predictions and observations motivates improved theory and can provide evidence for new physics. A predictive model of nuclei is needed as input for experimental tests and for astrophysical models.      Nuclei are complex strongly-interacting quantum many-body systems. Accurate theoretical techniques are required to predict the rate of nuclear decay processes, the cross section of nuclear reactions and the distribution of the emitted particles. Ab initio nuclear theory takes advantage of the recent rapid increase in computing power to calculate nuclear structure and reactions solely from realistic interactions between the constituent nucleons.      In this thesis, we first present beta-decay calculations using the ab initio no-core shell model. Our calculations provide an explanation for the quenching of Gamow-Teller beta-decays, provide nuclear structure corrections to the beta-spectrum necessary to interpret experiments seeking to find new physics and provide estimates for the hypothetical process of neutrinoless double-beta decay. Second, we present radiative capture calculations using the no-core shell model with continuum, an extension which places bound and scattering states on equal footing. The rate of radiative capture reactions in big bang nucleosynthesis is required to estimate the abundance of isotopes in the early universe. In addition, anomalies in recent radiative capture experiments claim the discovery of a new boson. Comparing to these experiments requires prediction of the distribution of electron-positron pairs produced by radiative capture. Event Location: https://ubc.zoom.us/j/61408939131?pwd=cGxvZDU4Zi9oTmVySjg1RTN2T1E5QT09, Passcode: 524103
Event Time: Monday, November 21, 2022 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
Add to Calendar 2022-11-21T15:00:00 2022-11-21T16:00:00 Machine Learning in the era of Time Domain Astronomy Event Information: Abstract: Astronomy surveys like the Zwicky Transient Facility have been leading to discoveries that are orders of magnitude more than just a decade ago.  The discoveries range from the Solar System (comets, NEAs etc.) to Galactic science (CVs, YSOs, binaries etc.), to extragalactic (distant supernovae, AGN, TDEs) and possible EM counterparts to multi-messenger transients. We will provide an overview of the plethora of discoveries, and the ongoing work. We will describe our plans for ramping up discoveries even further with the aid of machine learning, especially by combining the archives with fresh alerts.  With newer surveys, as we go fainter, cover more wavelengths, and go multi-messenger, more novel objects will be found. The rarity of these objects will both push the boundaries of our understanding, and also, due to the lack of statistically significant samples sometimes lead to premature claims, especially when using cutting-edge machine learning. We explore some aspects of time domain astronomy and its inherent biases, and comment on the requirement to explain the results through various techniques often involving post-hoc interpretability. Find out more about Dr. Ashish Mahabal's research and work here: https://sites.astro.caltech.edu/~aam/ Event Location: HENN 318
Event Time: Monday, November 21, 2022 | 11:00 am - 12:00 pm
Event Location:
HENN 318
Add to Calendar 2022-11-21T11:00:00 2022-11-21T12:00:00 Black hole evaporation in the Nariai limit Event Information: Abstract: In 1974, Stephen Hawking proposed the existence of Hawking radiation -- blackbody radiation that carries energy away from a black hole. This is thought to be the mechanism behind the evaporation of black holes. But in order for evaporation to happen, the energy needs to be able to go somewhere that is not the black hole. This talk will focus on my on-going research into the evaporation of a 1+1D Schwarzschild-de Sitter spacetime in the limit where the black hole horizon and the de Sitter horizon are degenerate (known as the Nariai limit). We investigate the (de)focusing effects caused by the energy flux of a massless, conformally coupled scalar field using one-loop effective action techniques. At present, we find that the flux does not cause the degenerate horizon to split, suggesting that a SdS black hole in the Nariai limit is stuck there, and will not evaporate. Event Location: HENN 318
Event Time: Thursday, November 17, 2022 | 4:00 pm - 5:00 pm
Event Location:
HEBB 114
Add to Calendar 2022-11-17T16:00:00 2022-11-17T17:00:00 Cosmology, Galaxy Formation, and Planets with JWST Event Information: Link to join remotely - look for today's date. The live stream will start at 4:00pm. Abstract:The modern standard cosmology ΛCDM describes almost perfectly the cosmic microwave background observations, but the resulting expansion rate of the universe (the Hubble parameter) is in serious disagreement with local measurements. This Hubble tension can perhaps be resolved by a brief episode of dark energy contributing about 10% of cosmic energy density for just a few thousand years about 50,000 years after the Big Bang.  This high-redshift Early Dark Energy (EDE) scenario can be tested at lower redshifts, since new N-body simulations show that EDE predicts earlier structure formation than ΛCDM, for example 50% more clusters at redshift z ∼ 1 and 10x more galaxies at z ~ 10. Such predictions are being tested by new observations, including by James Webb Space Telescope.  JWST’s infrared capabilities allow its cameras to see starlight from even the highest-redshift galaxies.  JWST’s better resolution than Hubble Space Telescope is also revealing  new aspects of galaxy and planet formation.  Earth is a Goldilocks planet, in the Sun’s habitable zone and also with just the right amount of radioactive heating by thorium and uranium for a long-lived magnetic field and plate tectonics — both of which may be necessary for the evolution of complex life. Such Goldilocks exoplanets, taking into account the abundance of Th and U deduced from the star’s spectrum, should be among the first planets to be searched by JWST for biosignatures.   Bio:    Dr. Joel R. Primack specializes in the formation and evolution of galaxies and the nature of the dark matter that makes up most of the matter in the universe. After helping to create what is now called the "Standard Model" of particle physics, Primack began working in cosmology in the late 1970s, and he became a leader in the new field of particle astrophysics.  His 1982 paper with Heinz Pagels was the first to propose that a natural candidate for the dark matter is the lightest supersymmetric particle.  He is one of the principal originators and developers of the theory of Cold Dark Matter, which has become the basis for the standard modern picture of structure formation in the universe.  With support from the National Science Foundation, NASA, and the Department of Energy, he has been using supercomputers to simulate and visualize the evolution of the universe and the formation of galaxies under various assumptions and comparing the predictions of these theories to the latest observational data. He organized and led the University of California systemwide Center for High-Performance AstroComputing (UC-HiPACC) 2010-2015. Primack has received a multitude of accolades over the years (including the APS Forum on Physics and Society Award in 1977, APS 1988, AAAS 1995) and has served on numerous boards, executive committees and advisory panels including such organizations as the APS Division of Astrophysics, the Federation of American Scientists, AAAS Committee on Scientific Freedom and Responsibility, the AAAS Science and Human Rights program, the AAAS Program of Dialogue on Science, Ethics, and Religion and the National Academy of Sciences.  Primack was one of the main advisors for the Smithsonian Air and Space Museum's 1996 IMAX film Cosmic Voyage, and he has worked with leading planetariums to help make the invisible universe visible.  In addition to more than 240 refereed technical articles in professional journals, Primack has written a number of articles aimed at a more popular audience. For more information about Dr. Joel R. Primack, please see his UC Santa Cruz research website. Event Location: HEBB 114
Event Time: Thursday, November 17, 2022 | 10:00 am - 11:00 am
Event Location:
BRIM 311
Add to Calendar 2022-11-17T10:00:00 2022-11-17T11:00:00 CM Seminar: Professor Kai-Mei Fu - Quantum point defects: Can these defects be less defective? Event Information:   Professor Kai-Mei Fu - University of Washington Title: Quantum point defects: Can these defects be less defective? Abstract: Point defects in crystals are the solid state analog to trapped ions. Thus these “quantum defects”, which can be integrated into solid-state devices, have gained popularity as qubit candidates for scalable quantum networks. In this talk, I will introduce some of the basic quantum defect properties desirable for quantum network applications. I will highlight my own group’s efforts at understanding and controlling the properties of defects in diamond including (1) synthesis, frequency and emission control of deep-level vacancy complexes in diamond and (2) properties of shallow-level donors in ZnO, including single donors and intentionally synthesized donors in ZnO. Bio: Kai-Mei Fu is the Virginia and Prentice Bloedel Professor of Physics and Electrical and Computer Engineering at the University of Washington and holds a dual appointment with the Pacific Northwest National Laboratory. Kai-Mei received their PhD in Applied Physics in 2007 from Stanford University. Their research focuses on the synthesis, characterization and control of optically active quantum defects in crystals, with applications in quantum networks and sensing. At UW, Kai-Mei is the Director of UW’s NSF National Research Training Program: Accelerating Quantum-Enabled Technologies and the co-chair of UW’s interdisciplinary QuantumX Steering Committee.  They are also the Deputy Director of the Department of Energy National Quantum Initiative (NQI) Co-design Center for Quantum Advantage. In their free time, Kai-Mei enjoys spending time with their family outdoors in the beautiful Pacific Northwest. Event Location: BRIM 311
Event Time: Monday, November 14, 2022 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
Add to Calendar 2022-11-14T15:00:00 2022-11-14T16:00:00 Detecting Pulsars with Neural Networks Event Information:   Abstract: Pulsars are rotating neutron stars which emit faint beams of electromagnetic radiation. In pulsar searches large effort is expended to discover these pulses in time- and frequency-resolved data from radio telescopes. Simultaneously recovering the frequency-dependent delay (dispersion) and the periodicity of the signal is a complex and demanding task, which is further exacerbated by the presence of various types of radio-frequency interference (RFI) and observing-system effects. I present a novel approach for the analysis of pulsar search data. I developed a neural-network-based pipeline that is able find pulsars directly in time- and frequency resolved data. The pipeline combines a convolutional neural network using dilated convolutions with standard algorithms for periodicity search such as the Fast Fourier Transform (FFT) and the Fast Folding Algorithm (FFA). This architecture can be trained in an end-to-end manner to identify faint pulses with an unknown amount of dispersion using a combination of simulated pulsars and unlabelled survey data as the training data. I present my training approach which allows the network to detect strong pulsars after a small amount of time and increase the sensitivity in subsequent training steps. Bio: Lars Künkel is a new post-doc here at PHAS. email: lkuenkel@phas.ubc.ca  office: Hennings 324     Event Location: HENN 318
Event Time: Monday, November 14, 2022 | 11:00 am - 12:00 pm
Event Location:
HENN 318
Add to Calendar 2022-11-14T11:00:00 2022-11-14T12:00:00 Quiet Coatings: Towards high throughput testing of mirror coating materials for gravitational wave detectors Event Information: TALK RECORDING AVAILABLE AT: https://drive.google.com/file/d/1mADq5Za4GFPS_9Y9er3nZivHHMcqEn_k/view?usp=share_link Abstract: Future generations of gravitational wave detectors will need improved mirror coatings so that they can be more sensitive than current detectors. These new mirror coatings must have a low mechanical loss so that they are as low noise – or as ‘quiet’ – as possible. There is a huge number of potential materials to test, so how can we do this testing quickly and efficiently, with as little material waste as possible? One approach, which I will present, is to miniaturize the devices onto which we put the coating materials. We can fabricate tiny mechanical microresonators, with hundreds of microresonators on one chip, and use these to measure coating loss via either free-space optics or integrated (on-chip) waveguides. I will give an overview of this work including device fabrication, the measurement technique and its unique advantages, and recent progress with our measurement system.   Event Location: HENN 318
Event Time: Thursday, November 10, 2022 | 10:00 am - 11:00 am
Event Location:
BRIM 311
Add to Calendar 2022-11-10T10:00:00 2022-11-10T11:00:00 CM Seminar: Joyce Poon - Visible-light Silicon Integrated Photonics for Future Computing Event Information: Joyce Poon - Max Planck Institute of Microstructure Physics Title: Visible-light Silicon Integrated Photonics for Future Computing Abstract: The emerging demands of computing require hardware advances to realize new types of computing architectures and interfaces. Foundry silicon photonics leverages the maturity of microelectronics manufacturing to fabricate photonic integrated circuits. Today, silicon photonics is mostly used in the short-wave infrared spectrum for optical communications. I will discuss how foundry silicon photonics in the visible spectrum is an enabling technology for future computing, addressing applications such as displays, neural implants, and quantum computing. Biography: Joyce Poon is the Managing Director at the Max Planck Institute of Microstructure Physics, a Professor of Electrical and Computer Engineering at the University of Toronto, and an Honorary Professor in the Faculty of Electrical Engineering and Computer Science at the Technical University of Berlin.  She currently serves as a Director-at-Large for Optica (formerly the Optical Society, OSA). She and her team specialize in integrated photonics on silicon.  Prof. Poon obtained the Ph.D. in Electrical Engineering from Caltech in 2007. She is a Optica Fellow and a Fellow of the IEEE. Event Location: BRIM 311
Event Time: Monday, November 7, 2022 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
Add to Calendar 2022-11-07T15:00:00 2022-02-07T16:00:00 3D Hydrodynamic Simulations of Convection and Internal Gravity Waves in Massive Stars Event Information:   Abstract: It is quite satisfying to tackle old problems with new techniques and finally get answers that we previously thought impossible to get. I will report on our latest generation of simulations of massive main-sequence stars that finally reveal in unprecedented detail and realism the properties of the turbulent flow in the convective core and the topology of the convective boundary that consists of a substantial almost adiabatic penetration layer. Through these simulations we can also understand properties of recently discovered low-frequency power excess in asteroseismic satellite observations of massive stars and we can constrain mixing due to internal gravity waves excited in the stable layers above the convective core. Bio: Falk Herwig leads the Computational Stellar Astrophysics group to conduct research in a range of topics related to the evolution, hydrodynamics and nuclear astrophysics of stars and stellar explosions of single and binary stars. The CSA group participates in the NSF Physics Frontier Center Joint Institute for Nuclear Astrophysics - Chemical Evolution of the Elements and is an active member of the NuGrid collaboration. The CSA computational research is supported by Compute Canada high-performance computing time allocations on the Niagara supercomputer. Dr Falk Herwig, Professor Dept of Physics & Astronomy University of Victoria https://www.uvic.ca/research/centres/arc/people/faculty/herwig-falk.phphttps://www.ppmstar.orghttps://canpan.ca Email: fherwig@uvic.ca Tel: +1 (250) 721-7743 Twitter: @fherwig   Event Location: HENN 318