Physics Commons^™

The Role Of Local Winds And A Semi-Persistent Coastal Front On The Diurnal Heat Budget In An Upwelling Bay, April P. Thibodeau, Ryan K. Walter, Piero L.F. Mazzini, Thomas P. Connolly, Christopher A. Edwards, Ian C. Robbins

Physics

Coastal embayments in nearshore upwelling systems (“upwelling bays”) play a disproportionately large role in regional oceanography. In these systems, local diurnal wind forcing and thermal gradients associated with an upwelling shadow front that forms between warmer sheltered waters inside the bay and colder recently upwelled waters outside the bay strongly influence local temperature dynamics. Despite their importance to local ecosystems, there are no long-term studies that assess the heat budget inside upwelling bays. In this study, we analyzed approximately two years of water temperature throughout the water column using an autonomous profiler in a small upwelling bay in central California …

Ecological Insights From Field And Laboratory Studies Of Akashiwo Sanguinea, Alexis L. Pasulka, Matthew J. Harke, Jaden Hansen, Ryan K. Walter, Eva Kokkino

Physics

Blooms of the dinoflagellate Akashiwo sanguinea occur in coastal ecosystems worldwide and can have significant ecological consequences. Along the central California coast, long-term oceanographic and harmful algal bloom observations indicate that A. sanguinea has exhibited seasonal blooms since approximately 2017, coinciding with negative upwelling anomalies and warm, stratified conditions characteristic of late summer and early fall. In laboratory experiments, three A. sanguinea strains isolated from different sites and/or environmental conditions along the central California coast exhibited variation in growth rates, temperature sensitivity, and transcriptional responses. Under the conditions tested in this study, one strain exhibiting higher maximum growth rates and …

Flagellar Coordination In A Swimming Multicellular Bacterium, Erandi Sachinthanie Imiya Mudiyanselage, Melina Mati, Alexander P. Petroff

Physics

Microbial locomotion is well understood when cells use either a small number of flagella or a high density of cilia. However many microbes live in an intermediate regime where coordination strategies such as flagellar bundles and metachronal waves are not possible. The mechanisms by which such organisms coordinate the motion of their swimming appendages are not well understood. Here, we study the only known obligatory multicellular bacterium, which are of the genus Magnetoglobus. Cells of this genus live exclusively in spherical communities called consortia, which are composed of a monolayer of tens of cells. Approximately a thousand of flagella project …

Electrical Resistivity Tomography Investigation Of Hard Rock Aquifers In The Salinian Block, Roxanne C. Chambers

Physics

Identifying a productive groundwater source in hard rock terrain is often a challenge. Conventional hard rock aquifer models commonly describe a weathering derived layered system consisting of a laminated layer, an underlying fractured zone, and a competent granitic basement. This study investigates the applicability of this conceptual model at Lockshaw Ranch, a granitic site within the Salinian Block of central California located near the Rinconada Fault.

Previous electrical resistivity tomography (ERT) surveys and time domain electromagnetic (TDEM) data were integrated with a newly acquired ERT profile (ERT-06) are used to characterize the subsurface structure and identify potential groundwater bearing zones. …

Muon Lifetime: Theory, Experiment, And Simulation, Soren Agustin Munoz

Physics

This senior project investigates the muon lifetime through three complementary approaches: theoretical calculation, laboratory measurement, and computational simulation. The theoretical component develops the necessary background from relativistic field theory to the effective weak interaction, culminating in the leading-order Fermi-theory prediction of τ ≈ 2.2 μs, which explains why the muon lifetime lies on the microsecond scale.

The experimental component measures the lifetime of stopped cosmic-ray muons using a plastic scintillator, photomultiplier tube, and analog timing electronics. A binned Poisson likelihood fit to the primary 15-day acquisition run τ = 2.17^+0.03_-0.09 μs, consistent with the accepted value within the …

Validation Of Electromagnetic Shower Development In A Reduced Alice Focal-E Detector Model Using Geant4, Isaac Lara Romo

Physics

This project focuses on the preliminary simulation of a reduced FoCal-E detector model for the ALICE experiment at CERN. Beamline tests were simulated using an electron gun at various incident energies, and the results were compared with those of the FoCal group. The longitudinal charge deposition per sensor layer was compared between the two setups to verify that the reduced model exhibited expected calorimeter behavior. Additionally, the transverse signal across the high-granularity sensor layers was examined to determine whether the reduced model reproduced the expected lateral development of electromagnetic showers. The results obtained from these measurements show that the reduced …

The Implementation Of Scintillation Detectors With The Cuore/Cupid Collaboration In The Search For Neutrinoless Double Beta Decay, Reese Sandra Cormier

Physics

CUORE (Cryogenic Underground Observatory for Rare Events) is an experiment at the Gran Sasso National Laboratory in Assergi, Italy, currently searching for an answer to the matter-antimatter asymmetry problem; the question: why do we exist? One proposed explanation is neutrinoless double beta decay, a theorized exotic decay that would prove that neutrinos are their own antiparticle, violating the current Standard Model for particle physics. However, current detection methods do not distinguish different types of particle interactions, resulting in alpha decays contributing to the background. Therefore, the experimental sensitivity is too limited to make confident determinations about the data. For this …

Experimental Methods For Cryogenic Rare Event Detection: Cuore And Cupid, Alessandro Libenson

Physics

This senior project was written with the primary purpose of serving as a introductory guide for undergraduate students learning about the experimental methods used in the CUORE and CUPID Collaborations. In particular, this project is geared towards getting students in Dr. Gutierrez's research group at Cal Poly up to speed on what CUORE and CUPID actually do. I wrote this as an undergraduate aiming to help future undergraduates. For Cal Poly students, I would suggest the following prerequisites before reading this paper: Electronics and Instrumentation, Quantum Laboratory 1, and the equivalent of the coding/analysis class. It is also important to …

Spatial Extent And Vertical Structure Of Marine Heatwaves In Chesapeake Bay, Nathan P. Shunk, Piero L. F. Mazzini, Ryan K. Walter, Kyle E. Hinson, Pierre St-Laurent, Marjorie A. M. Friedrichs

Physics

Marine heatwaves (MHWs) adversely impact marine ecosystems globally, yet data scarcity limits our understanding of their subsurface extent, particularly in estuaries. Using a high-resolution regional ocean model, we characterized the horizontal extent and subsurface structure of MHWs across the Chesapeake Bay (CB). Additionally, we developed a supplementary definition for local climatology-identified MHWs, “Vertical MHWs,” which quantifies their water column presence, and developed a new MHW vertical classification scheme. Surface MHWs were generally shorter, more frequent and intense, and impacted ∼5% of the CB surface area, while the deepest MHWs were generally longer, less frequent and intense, and regularly occupied >50% …

Marine Heatwave Co-Occurrence Between Estuarine And Coastal Systems, Ricardo U. Nardi, Piero L. F. Mazzini, Ryan K. Walter

Physics

Marine heatwaves (MHWs), prolonged periods of anomalously warm ocean temperatures, pose significant threats to marine ecosystems. While MHWs in coastal and estuarine systems have been studied separately, their spatial coherence remains significantly understudied. Here we analyze over 2 decades of high-frequency in situ temperature data from 54 stations across 20 U.S. estuaries and 13 coastal buoys to assess MHW co-occurrences. We find that estuarine and coastal MHWs co-occur only ∼21% of the time, a 57% decrease compared to co-occurrence within estuaries (∼49%). Maximum co-occurrence occurs at zero lag, suggesting synchronous synoptic-scale atmospheric forcing, likely via air–sea heat fluxes. Co-occurrence shows …

Conditions Of Coherent-Phonon Excitation In Srmnsb2 Films And Crystals, Manita Rai, Sujan Subedi, Hannah E. Aguirre, Hans A. Bechtel, Renee Chapla, Javier Garcia De Castro, Dennis D. Klug, Jinyu Liu, Madison G. Masten, Trung Hieu Nguyen, Thomas J. Rehaag, Yiyi Wang, Zhiqiang Mao, Gavin R. Bell, Darius H. Torchinsky, Christopher Weber

Physics

Excitation of coherent phonons has the potential to dramatically alter the electronic structure of Dirac and Weyl semimetals, enabling sub-picosecond control of their optical and electronic properties. The Dirac semimetal SrMnSb is a candidate for such control, with a coherent-phonon mode that is predicted to close and reopen a gap at the Dirac node. Here, through a series of ultrafast pump-probe experiments, we establish suitable samples and conditions for driving the coherent phonon to high amplitude and attempting to observe the gap’s closure. Films of SrMnSb grown by molecular-beam epitaxy are shown to have phononic properties matching those of bulk …

Spatially Resolved [O Iii] Emission Line Kinematics Of Reverberation-Mapped Active Galactic Nuclei With The Keck Cosmic Web Imager, Raymond P. Remigio, Vivian U, Aaron J. Barth, Nico Winkel, Vardha N. Bennert, Tommaso Treu, Matthew A. Malkan, Sebastian Contreras, Peter R. Williams, Jordan N. Runco

Physics

We present optical integral-field spectroscopic data of ten nearby (0.02 ≤ z ≤ 0.05) Seyfert 1 galaxies taken with the Keck Cosmic Web Imager. We map the spatially resolved kinematics of the [O iii] gas and stars, and investigate the alignments between their global kinematic position angles (PAs). Large-scale gas motions are primarily dominated by rotation and are kinematically aligned with the stars (ΔPA ≤ 30°). However, eight galaxies exhibit nonrotational kinematic signatures (e.g., kinematic twists, possible outflows) in their ionized gas velocity fields near the nucleus. We compare aperture-wide measurements of the gas and stellar velocity dispersions (σ …

Gravitational Torques From Lopsided Young Stellar Component Sustain High Black Hole Accretion Rates In Ngc 4593, N. Winkel, K. Jahnke, J. A. Fernández-Ontiveros, T. A. Davis, F. Combes, M. Gaspari, J. Neumann, M. Singha, J. S. Elford, Vardha N. Bennert, M. A. Malkan

Physics

Context. Supermassive black holes (SMBHs) grow primarily through gas accretion, observed as active galactic nuclei (AGNs). While mergers can drive luminous AGN episodes, secular processes may fuel a substantial portion of cosmic black hole growth. Whether these mechanisms can sustain high black hole accretion rates remains uncertain.

Aims. The aim of this study is to identify the secular mechanism driving high SMBH accretion rates, by targeting a galaxy with a moderately massive SMBH, high central gas densities, accretion rates of a few percent of the Eddington limit, and gas kinematics resolved close to black-hole-dominated scales.

Methods. A blind search led …

Spatially Resolved Kinematics Of Slacs Lens Galaxies. I. Data And Kinematic Classification, Shawn Knabel, Tommaso Treu, Michele Cappellari, Anowar J. Shajib, Chih-Fan Chen, Simon Birrer, Vardha N. Bennert

Physics

We obtain spatially resolved kinematics with the Keck Cosmic Web Imager (KCWI) integral-field spectrograph for a sample of 14 massive (11 < log₁₀(M₍★₎/M☉) < 12) lensing early-type galaxies at z ∼ 0.15–0.35 from the Sloan Lens ACS (SLACS) Survey. We integrate kinematic maps within the galaxy effective radius and examine the rotational and dispersion velocities, showing that 11/14 can be classified as slow rotators. The data set is unprecedented for galaxy-scale strong lenses in terms of signal-to-noise ratio (S/N), sampling, and calibration, vastly superseding previous studies. We find the primary contributions to systematic uncertainties to be the stellar template library and wavelength range of the spectral fit. Systematics …

Marine Heatwaves Detected By A Network Of Buoys Along The Entire Us West Coast Shelf, Gavin Plume, Ryan K. Walter, Piero L.F. Mazzini, Michael Dalsin

Physics

Marine heatwaves (MHWs), prolonged periods of anomalously warm waters, pose an increasing threat to marine ecosystems globally. While satellite-based data offer insights into MHW patterns, coastal upwelling regions are prone to satellite biases and require long-term in-situ datasets for accurate characterization. Using two decades of temperature data from 22 surface buoys distributed along the US West Coast continental shelf (10–50 km offshore) spanning nearly 2000 km of coastline, we investigated, for the first time, coast-wide patterns of MHWs in this valuable region. The spatial extent of MHWs varied from 100% of buoys during the 2014–2016 North Pacific MHW, to less …

Spatio-Temporal Variability Of San Francisco Bay Plume From Space, Piero L. F. Mazzini, Cassia Pianca, L. Fernando Pareja-Roman, Kelly L. Cole, Ryan K. Walter, Renato M. Castelao, Elias J. Hunter, Robert J. Chant

Physics

As brackish turbid waters exit San Francisco Bay, one of the largest estuaries in the U.S. West Coast, they form the San Francisco Bay Plume (SFBP), which spreads offshore and influences the Gulf of the Farallones (GoF), an ecologically significant region in the California Current System that is also home to three National Marine Sanctuaries. This paper provides the first observationally based investigation of the spatio-temporal variability of the SFBP, using a plume tracking algorithm applied to more than two decades (2002-2023) of ocean color data from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard satellites Aqua and Terra. The …

The Gauge/Gravity Holographic Duality Between String Theory And Quantum Field Theory: A Full Introduction, Alex A. Short

Physics

The Anti-deSitter Spacetime / Conformal Field Theory (AdS/CFT) correspondence is a well known holographic duality between ten dimensional superstring theories and conformal quantum field theories. The existence of such a correspondence is fascinating and the duality provides a powerful tool-set for working out problems in both string theory and quantum field theory. The correspondence defines a dictionary of terms that exist dual to one another in each theory, allowing theorists to understand the dynamics in one system based on quantities from another. Furthermore, when one side of the duality has strong coupling (meaning the approximations of perturbation theory are no …

Gaussian Process Regression And Nested Sampling For Planetary Parameter Prediction, Alexandro Balarezo

Physics

In this project, we implemented a Gaussian Process (GP) regression framework using MATLAB to model two planetary (Earth) parameters, the surface temperature and albedo, as functions of planetary rotation rate and insolation (the amount of sunlight impinging on the planet). We used simulation data from the NASA ROCKE-3D general circulation model developed by the NASA Goddard Institute for Space Studies (GISS). The GP model generates a joint multivariate Gaussian distribution that is entirely captured by a covariance matrix and the output of a training data set. The covariance matrix is determined by the input data and the three hyperparameters a …

Seoul National University Agn Monitoring Project. V. Velocity-Resolved Hβ Reverberation Mapping And Evidence Of Kinematics Evolution, Shu Wang, Jong-Hak Woo, Aaron J. Barth, Vardha N. Bennert, Elena Gallo, Edmund Hodges-Kluck, Minjin Kim, Suvendu Rakshit, Tommaso Treu, Hojin Cho

Physics

We present velocity-resolved reverberation lags of Hβ for 20 active galactic nuclei (AGNs) from the Seoul National University AGN Monitoring Project. We detect unambiguous velocity-resolved structures in 12 AGNs, among which eight objects exhibit symmetric structures, two objects show inflow-like characteristics, and two objects display outflow-like signatures. For two AGNs, we successfully measure the velocity-resolved lags in different years, revealing evidence of evolving broad-line region (BLR) kinematics. By combining our sample with the literature velocity-resolved lags, we find that the symmetric velocity-resolved lags are the most common (40%) type among this sample. The frequency of inflow kinematics is also …

Climate Change And Variability Drive Increasing Exposure Of Marine Heatwaves Across Us Estuaries, Ricardo U. Nardi, Piero L. F. Mazzini, Ryan K. Walter

Physics

Marine heatwaves (MHWs) are among the greatest threats to marine ecosystems, and while substantial advances have been made in oceanic MHWs, little is known about estuarine MHWs. Utilizing a temperature dataset spanning over two decades and 54 stations distributed across 20 estuaries in the United States National Estuarine Research Reserve System, we present a comprehensive analysis of estuarine MHW characteristics and trends. Long-term climate-change-driven warming is driving more frequent MHWs along the East Coast, and if trends continue, this region will be in a MHW state for ~ 1/3 of the year by the end of the century. In contrast, …

Muon Veto Panel Uniformity Tests At Yale Wright Laboratory For The Cuore And Cupid Experiments And Visualizing Dirac Spinors In The Chiral Basis With The Bloch Sphere, Reagen Neeva Garcia

Physics

This senior project is divided into three sections that describe my path and experiences in under graduate research. The first provides an introduction to the field of particle physics and the search for neutrinoless double beta decay (0νββ) with the Cryogenic Underground Observatory for Rare Events (CUORE) experiment, as well as its upgrade, CUPID (CUORE Upgrade with Particle IDentification). The second section details my contributions to these experiments, including my summer working at Yale’s Wright Laboratory on R&D for the CUPID experiment. In this section I describe my work on the experiment’s muon veto system and on light detector development …

Vertical Structure Of Subsurface Marine Heatwaves In A Shallow Nearshore Upwelling System, Gavin Plume, Ryan K. Walter, Isabelle Cobb, Michael Dalsin, Piero L. F. Mazzini, Nathan P. Shunk, Ian C. Robbins, Thomas P. Connolly

Physics

Marine heatwaves (MHWs) are increasing in frequency and intensity globally and are among the greatest threats to marine ecosystems. However, limited studies have characterized subsurface MHWs, particularly in shallow waters. We utilized nearly two decades of full water-column (~ 10 m) observations from a unique automated profiler in central California to characterize, for the first time, the vertical structure of MHWs in a shallow nearshore upwelling system. We found MHWs have similar average durations and intensities across all depths, but there were ~ 17% more bottom MHW days than surface MHW days. Nearly one third of bottom MHWs occurred independently …

Offshore Wind Farms Could Impact Coastal Marine Heatwaves In Eastern Boundary Upwelling Systems, Michael Dalsin, Ryan K. Walter, Piero L.F. Mazzini

Physics

Analysis of ecosystem impacts from offshore wind (OSW) farm development has primarily focused on localized effects. However, in Eastern Boundary Current Upwelling Systems (EBUS) like the California Current, OSW farms can modify the intensity and spatial structure of wind-driven upwelling, inducing non-local (tens of kms away) changes to seawater temperature. Recent numerical modeling research determined that a hypothetical upper bound full buildout of OSW farms in central California could warm coastal waters through a reduction in upwelling. Here, we examine the sensitivity of coastal marine heatwaves (MHWs), which are prolonged extreme seawater temperatures that are among the greatest threats to …

Jwst Lensed Quasar Dark Matter Survey – Ii. Strongest Gravitational Lensing Limit On The Dark Matter Free Streaming Length To Date, Ryan E. Keeley, A. M. Nierenberg, D. Gilman, C. Gannon, S. Birrer, T. Treu, A. J. Benson, X. Du, K. N. Abazajian, Vardha N. Bennert

Physics

This is the second in a series of papers in which we use JWST Mid Infrared Instrument multiband imaging to measure the warm dust emission in a sample of 31 multiply imaged quasars, to be used as a probe of the particle nature of dark matter. We present measurements of the relative magnifications of the strongly lensed warm dust emission in a sample of nine systems. The warm dust region is compact and sensitive to perturbations by populations of haloes down to masses ~ 10⁶ M☉. Using these warm dust flux-ratio measurements in combination with five previous narrow-line flux-ratio measurements, …

Settling Of Two Rigidly Connected Spheres, Z. Maches, Morgane Houssais

Physics

Laboratory experiments and particle-resolved simulations are employed to investigate the settling dynamics of a pair of rigidly connected spherical particles of unequal size. They yield a detailed picture of the transient evolution and the terminal values of the aggregate's orientation angle and its settling and drift velocities as functions of the aspect ratio and the Galileo number, which denotes the ratio of buoyancy and viscous forces acting on the aggregate. At low to moderate values of, the aggregate's orientation and velocity converge to their terminal values monotonically, whereas for higher -values the aggregate tends to undergo a more complex motion. …

Spatial Planning Offshore Wind Energy Farms In California For Mediating Fisheries And Wildlife Conservation Impacts, Crow White, Yi-Hui Wang, Ryan K. Walter, Benjamin Ruttenberg, Danny Han, Eli Newman, Ethan R. Deyle, Sucharita Gopal, Les Kaufman

Physics

Achieving a blue economy will require reconciling the value of emerging ocean uses with their impacts on the seascape and sectors with historical access to marine resources and areas. To meet this challenge, we developed an analytical framework for conducting marine spatial planning through tradeoff analysis, and applied it to prospective offshore wind energy development in the ∼974 km2 Morro Bay, California, USA Wind Energy Area (WEA). We generated spatial data layers estimating MW power production and impacts on fisheries value and marine wildlife conservation (seabird and cetacean populations) from wind farm development. We then quantified each sector's response to …

Soft Matter Physics Of The Ground Beneath Our Feet, Anne Voigtländer, Morgane Houssais, Karol A. Bacik, Ian C. Bourg, Justin C. Burton, Karen E. Daniels, Sujit S. Datta, Emanuela Del Gado, Nakul S. Deshpande, Olivier Devauchelle, Behrooz Ferdowsi, Rachel Glade, Lucas Goehring, Ian J. Hewitt, Douglas Jerolmack, Ruben Juanes, Arshad Kudrolli, Ching Yao Lai, Wei Li, Claire Masteller, Kavinda Nissanka, Allan M. Rubin, Howard A. Stone, Jenny Suckale, Nathalie M. Vriend, John S. Wettlaufer, Judy Q. Yang

Physics

The soft part of the Earth's surface - the ground beneath our feet - constitutes the basis for life and natural resources, yet a general physical understanding of the ground is still lacking. In this critical time of climate change, cross-pollination of scientific approaches is urgently needed to better understand the behavior of our planet's surface. The major topics in current research in this area cross different disciplines, spanning geosciences, and various aspects of engineering, material sciences, physics, chemistry, and biology. Among these, soft matter physics has emerged as a fundamental nexus connecting and underpinning many research questions. This perspective …

High Resolution Assessment Of Commercial Fisheries Activity Along The Us West Coast Using Vessel Monitoring System Data With A Case Study Using California Groundfish Fisheries, Yi-Hui Wang, Benjamin Ruttenberg, Ryan K. Walter, Frank Pendleton, Jameal F. Samhouri, Owen R. Liu, Crow White

Physics

Commercial fisheries along the US West Coast are important components of local and regional economies. They use various fishing gear, target a high diversity of species, and are highly spatially heterogeneous, making it challenging to generate a synoptic picture of fisheries activity in the region. Still, understanding the spatial and temporal dynamics of US West Coast fisheries is critical to meet the US legal mandate to manage fisheries sustainably and to better coordinate activities among a growing number of users of ocean space, including offshore renewable energy, aquaculture, shipping, and interactions with habitats and key non-fishery species such as seabirds …

Identifying Ion-Scale Waves In Parker Solar Probe Sub-Alfvénic Intervals, Nicholas Henry Androski, Kristoff Paulson

Physics

Identification of coherent quasi-parallel ion-scale (1-32 Hz) wave activity in sub-Alfvénic regions of the solar wind observed by NASA's Parker Solar Probe during perihelion encounters 8 to 16. Wave activity is filtered computationally by coherency, circular polarization and propagation angle with respect to the mean magnetic field. Initial statistical results are presented with suggestions for future improvements and studies. A general overview of the heliosphere and the context of ion-cyclotron waves (an ion-scale wave) in the coronal heating problem. Along the way to identify ion-scale wave activity, tables of sub-Alfvénic intervals and current sheet crossings for encounters 8 to 16 …

Compound Marine Cold Spells And Hypoxic Events In A Nearshore Upwelling System, Ryan K. Walter, Michael Dalsin, Piero L.F. Mazzini, Cassia Pianca

Physics

Prolonged periods of extreme warm and cold seawater temperature anomalies, known as marine heatwaves (MHWs) and marine cold spells (MCSs), respectively, can have significant impacts on coastal marine ecosystems. Prior research has examined the co-occurrence of multiple extremes [low dissolved oxygen (DO) and/or low pH] during MHWs, with the impact of these compound events potentially exceeding that of a single stressor due to synergistic effects. However, we are not aware of any studies that have examined compound extreme events during MCSs, despite the ecosystem implications. Along Eastern Boundary Current Upwelling Systems (EBUS), strong-wind driven upwelling has led to …