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The properties of a material are often thought to be determined primarily by the elements from which it is made. But what happens when the geometry of a crystal lattice itself becomes a source of new quantum phenomena? In this talk, I will explore this question through the physics of kagome metals—materials whose atoms form a network of corner-sharing triangles. The kagome lattice provides a remarkable example of how geometry can reshape the electronic landscape of a metal. Quantum interference between electronic pathways produces nearly flat electronic bands, while the same lattice can host Dirac-like band crossings and van Hove singularities, where the density of electronic states becomes strongly enhanced. These features can dramatically amplify the effects of interactions between electrons, creating an unusually rich environment for collective quantum phenomena. Kagome materials have consequently emerged as a platform for studying charge-density waves, magnetism, unconventional superconductivity, nematicity, anomalous Hall responses, and other forms of intertwined and potentially topological order. I will discuss how these ideas emerge from the electronic structure and how they manifest experimentally in real materials. In particular, I will highlight recent work from my group using the experimental technique of angle-resolved photoemission spectroscopy (ARPES) to directly visualize the electronic states of several kagome metals and to follow their evolution across the various phase transitions. These experiments reveal an intimate connection between the underlying band structure and the collective behavior of the electrons, while also highlighting the ways in which real materials can depart from simple theoretical pictures.
| Temp: | 86 °F | N2 Boiling: | 75.9 K |
| Humidity: | 12% | H2O Boiling: | 368.4 K |
| Pressure: | 85 kPa | Sunrise: | 6:58 AM |
| Wind: | 3 m/s | Sunset: | 7:53 PM |
| Precip: | 0 mm | Sunlight: | 312 W/m² |
Selected Publications
We present You Only Stack Once (YOSO), an automated pipeline designed to detect faint, slow-moving solar system objects in wide-field astronomical surveys. The pipeline integrates a novel Gaussian motion filter (GMoF) that operates at the pixel level to enhance the signal-to-noise ratio for objects exhibiting a range of apparent rates of motion. Unlike conventional shift-and-stack methods, which rely on discrete velocity trials, GMoF amplifies trails while suppressing random noise and static background features. Applied to a subset of DEEP observations from the Dark Energy Camera, YOSO discovered 45 out of 73 previously detected objects, as well as 11 new trans-Neptunian objects. It also discovered 216 objects in the near solar system. Although alternative shift-and-stack methods are sensitive to objects about 0.88 mag fainter, YOSO’s false-positive rate is extremely low, since it detects only sources that exhibit a trail and are consistent with a point source when shifted at the right rate. We show how this method can be deployed on large surveys like LSST, and be adapted for other domains that require motion-based signal enhancement, including exoplanet imaging through angular differential imaging and near-Earth object (NEO) detection for missions like the NEO Surveyor. YOSO thus provides a versatile, scalable approach for extracting faint, motion-dependent signals in the era of data-intensive astronomy.
Glycosylation is the most common post-translational modification in the human proteome, with over half of all human proteins bearing covalently attached glycans. These glycan structures direct protein folding through ER quality control machinery, shield polypeptides from proteolytic degradation, regulate circulatory half-life via the asialoglycoprotein receptor, and serve as molecular signals for immune recognition and intracellular trafficking. For biopharmaceuticals, which constitute a rapidly growing share of approved drugs, glycan profiles are critical quality attributes that directly determine clinical efficacy and safety. Yet achieving the correct glycosylation on a therapeutic protein remains one of the field’s central challenges, as glycan biosynthesis is non-template-driven and highly sensitive to expression system and manufacturing conditions. This review connects the biological functions of glycosylation to the practical strategies of glycoengineering, examining how sequence design, expression system selection, and downstream enzymatic remodeling are used to optimize therapeutic glycoproteins. Clinical case studies spanning monoclonal antibodies, cytokines, and enzyme replacement therapies illustrate how glycan engineering translates into improved patient outcomes. We conclude by surveying emerging technologies poised to make precisely glycosylated therapeutics more accessible.
Rocket launches generate acoustic environments that impact nearby communities, motivating the need for tools to predict launch noise at the community level. RUMBLE is a computational rocket noise prediction model that produces spatial predictions of acoustic metrics but offers limited temporal resolution, complicating direct comparison with field measurements. This paper tests whether RUMBLE-predicted unweighted maximum sound levels (Lmax) agree with community-level measurements from nine Falcon 9 Block 5 launch events recorded near Cape Canaveral, Florida. Field measurements were obtained using Larson–Davis sound level meters deployed at residential distances of approximately 20–25 km from active launch pads. Because RUMBLE outputs only scalar metrics without time histories, a rolling Lmax analysis using Z-weighting and slow exponential time weighting was developed to enable direct comparison. Across nine launch events, RUMBLE-predicted Lmax values agreed with measured community levels within 5 dB, with mean absolute differences of 3.5 dB for Space Launch Complex 40 operations and 2.8 dB for Launch Complex 39A operations. These results demonstrate that Lmax is an effective scalar metric for validation of RUMBLE predictions at community locations. While the absence of time-domain and spectral outputs limits more detailed comparisons, the results provide a foundation for future model development and monitoring efforts.
It is inherently challenging to characterize long-period transiting exoplanets because the transit events are rare and last long. These systems provide unique insights into planetary formation, migration, the detection of exomoons, and primordial atmospheres by occupying a sparsely populated region of the exoplanet parameter space, however. The complexity increases further for long-period planets near mean-motion resonances, where transit timing variations (TTVs) can reach amplitudes of several hours to days. We present a coordinated space- and ground-based observing campaign using photometry from NEOSSat, multiple LCOGT sites, MuSCAT, MuSCAT3, Tierras, and NGTS to capture the 19-hour transit of the long-period giant exoplanet HIP 41378f (P ≈ 542 d, R ≈ = 9.5 R⊕) on 31 October 2025. Our transit analysis constrains the time of inferior conjunction to TC = 2460980.888 ± 0.029 BJDTDB, occurring ∼ 7 hours earlier than predicted from its linear ephemeris. This significant offset is consistent with the previously reported TTVs of HIP41378f, confirming it as the longest-period exoplanet known to exhibit measurable TTVs. By combining this new precise measurement with the transit timings of the two outer planets in the system (HIP41378d and HIP41378e), we performed a dynamical modeling of the system using the N-body integrator TRADES, refined the ephemeris of HIP41378f, and predict future transit events for all three outer transiting planets.
With the great success of stellar occultations in probing trans-Neptunian objects (TNOs), these observations have become ubiquitous, leading to significant advances in our knowledge of TNOs. As stellar occultation predictions have improved, it has become feasible to predict and observe stellar occultations by satellites of TNOs. In this work, we develop a robust methodology for predicting occultations by large TNO satellites based on the most up-to-date and accurate ephemerides available. We validated our methodology by reproducing several previously recorded occultations by Hi‘iaka, and then used it to predict—and successfully observe—stellar occultations of two other satellites, Namaka and Tinia. As a demonstration of the scientific return of such occultations, we provide the detailed prediction, observation, and analysis of the Tinia occultation. For the satellite of Uni (2002 UX25), we recorded two positive occultation chords that yielded projected circular and elliptical profiles with equivalent diameters of 180.8 ± 0.6 and 193.0 ± 1.0 km, respectively. Using the published absolute magnitude for the system and Tinia’s relative brightness with respect to the primary, we derived an absolute magnitude of HV = 6.476 ± 0.183 mag for Tinia. This corresponds to geometric albedo values of ρV = 0.139 ± 0.023 and ρV = 0.122 ± 0.02 for circular and elliptical solutions, respectively. Under the assumption of equal albedos, we obtained a diameter of D = 571 ± 53 km and D = 610 ± 53 km for the primary. Our methods provide a precise, simple, open-source technique for predicting TNO satellite occultations, enabling diverse investigations into the properties of TNOs and their satellites as demonstrated for Tinia.
Magnetic pyrochlores with non-Kramers rare-earth ions provide a platform for exploring emergent gauge physics and quantum spin-ice behavior, yet the influence of structural disorder on their ground states remains insufficiently understood. Here we combine bulk characterization and single-crystal neutron-scattering measurements to investigate the non-Kramers pyrochlore Pr2Sn2O7. At temperatures below ∼1 K, the system exhibits key hallmarks of quantum spin-ice physics, including anisotropic spin-ice correlations and two distinct dynamical timescales. Upon further cooling, however, we observe a complete spin-freezing transition at Tf≈0.15 K, accompanied by recovery of the full nuclear Schottky anomaly, the emergence of a gapped magnetic excitation, and the development of incipient (100) magnetic correlations. Comparison with related Pr-based pyrochlores places Pr2Sn2O7 near the spin-frozen boundary of a disorder-perturbed phase diagram. These results establish a disorder-driven framework for the evolution of quantum spin-ice behavior into frozen ground states, revealing how signatures of a proximate quantum spin liquid can persist despite disorder-induced spin freezing in non-Kramers pyrochlores.