Open Access. Powered by Scholars. Published by Universities.®

Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

California Polytechnic State University, San Luis Obispo

Discipline
Keyword
Publication Year
Publication
Publication Type

Articles 31 - 60 of 920

Full-Text Articles in Physics

Exploration On Lysing Microalgae Using Pulsed Electric Fields, Fereshteh A. Bunk Apr 2024

Exploration On Lysing Microalgae Using Pulsed Electric Fields, Fereshteh A. Bunk

Physics

With a dangerously and rapidly changing climate [1], people globally are desperate to reduce CO2 emissions and protect our environment as evidenced by global initiatives such as the United Nations’ Paris Agreement [2]. Traditional fossil fuel extraction and combustion was responsible for 74% of U.S. greenhouse gas emissions in 2019, which contributes to climate change, ocean acidification, extreme weather events, sea level rise, pollution, and health issues which contributed to 350,000 premature deaths in the U.S. in 2018 [3]. This motivates the search for alternative, more sustainable fuel production. There have been many new, more sustainable solutions to traditional fossil …


Non-Relativistic Limit Of Selected Terms From The Sme Dirac Lagrangian, Quinn Reece Mar 2024

Non-Relativistic Limit Of Selected Terms From The Sme Dirac Lagrangian, Quinn Reece

Physics

We examine a selection of individual CPT/Lorentz violating terms present in the relativistic lagrangian for a free spin- 1 2 Dirac fermion of mass m in the Standard Model Extension. Euler-Lagrange relations will be applied to give Dirac-like equations including these terms and a novel procedure will be used to generate non-relativistic limits of these equations which are Schr¨odinger-Pauli-like equations. These equations will be analyzed using classical quantum mechanics toy problems to gain physical intuition for the effects of the CPT violating terms, and the results will be discussed. We will conclude with discussion on future work will include the …


Impacts Of Marine Heatwaves On Subsurface Temperatures And Dissolved Oxygen In The Chesapeake Bay, Nathan P. Shunk, Piero L. F. Mazzini, Ryan K. Walter Feb 2024

Impacts Of Marine Heatwaves On Subsurface Temperatures And Dissolved Oxygen In The Chesapeake Bay, Nathan P. Shunk, Piero L. F. Mazzini, Ryan K. Walter

Physics

Subsurface impacts associated with Marine Heatwaves (MHWs) in estuaries are not well understood, largely due to data scarcity. Using over three decades (1986–2021) of observations from several monitoring programs, this study investigates subsurface temperature and dissolved oxygen (DO) anomalies associated with surface MHWs in the Chesapeake Bay (CB). Seasonal variability in temperature anomalies followed a simple 1-D response to surface heating with downward heat transport and diffusion controlled by seasonally variable stratification and mixing. Two distinct temperature regimes were found: a thermally stratified spring-summer regime, when positive temperature anomalies were confined to the surface mixed layer (SML); and a homogeneous …


Jwst Lensed Quasar Dark Matter Survey – I. Description And First Results, A. M. Nierenberg, R. E. Keeley, D. Sluse, D. Gilman, S. Birrer, T. Treu, K. N. Abazajian, T. Anguita, A. J. Benson, Vardha N. Bennert Feb 2024

Jwst Lensed Quasar Dark Matter Survey – I. Description And First Results, A. M. Nierenberg, R. E. Keeley, D. Sluse, D. Gilman, S. Birrer, T. Treu, K. N. Abazajian, T. Anguita, A. J. Benson, Vardha N. Bennert

Physics

The flux ratios of gravitationally lensed quasars provide a powerful probe of the nature of dark matter. Importantly, these ratios are sensitive to small-scale structure, irrespective of the presence of baryons. This sensitivity may allow us to study the halo mass function even below the scales where galaxies form observable stars. For accurate measurements, it is essential that the quasar’s light is emitted from a physical region of the quasar with an angular scale of milliarcseconds or larger; this minimizes microlensing effects by stars within the deflector. The warm dust region of quasars fits this criterion, as it has parsec-size …


The Seoul National University Agn Monitoring Project. Iii. Hβ Lag Measurements Of 32 Luminous Active Galactic Nuclei And The High-Luminosity End Of The Size–Luminosity Relation, Jong-Hak Woo, Shu Wang, Suvendu Rakshit, Hojin Cho, Donghoon Son, Vardha N. Bennert, Elena Gallo, Edmund Hodges-Kluck, Tommaso Treu, Aaron J. Barth Feb 2024

The Seoul National University Agn Monitoring Project. Iii. Hβ Lag Measurements Of 32 Luminous Active Galactic Nuclei And The High-Luminosity End Of The Size–Luminosity Relation, Jong-Hak Woo, Shu Wang, Suvendu Rakshit, Hojin Cho, Donghoon Son, Vardha N. Bennert, Elena Gallo, Edmund Hodges-Kluck, Tommaso Treu, Aaron J. Barth

Physics

We present the main results from a long-term reverberation mapping campaign carried out for the Seoul National University AGN Monitoring Project (SAMP). High-quality data were obtained during 2015–2021 for 32 luminous active galactic nuclei (AGNs; i.e., continuum luminosity in the range of 1044–46 erg s−1) at a regular cadence, of 20–30 days for spectroscopy and 3–5 days for photometry. We obtain time lag measurements between the variability in the Hβ emission and the continuum for 32 AGNs; 25 of those have the best lag measurements based on our quality assessment, examining correlation strength and the posterior lag distribution. Our …


Interactive Water Vortex Exhibit, Simon Way, Emily Laing, Roqaya Naseri, Makenzie Kan Dec 2023

Interactive Water Vortex Exhibit, Simon Way, Emily Laing, Roqaya Naseri, Makenzie Kan

Mechanical Engineering

The San Luis Obispo Children’s Museum requested an interactive water vortex exhibit to both engage and entertain inquisitive guests, ages two to eight. The goal was to design and manufacture an exhibit that would educate its users on the fluid mechanics behind water vortices. They activate the mechanics by spinning a wheel, which is perceived as the catalyst to manipulate the flow of water to successfully create a whirlpool. Our team has created an interactive display that will enlighten young minds, providing the museum with an educational exhibit which shares a concept not currently taught by any other. Our project …


Decades Of Eelgrass Meadow Dynamics Across The Northeast Pacific Support Seascape-Scale Conservation, S. H. Munsch, Ryan K. Walter, B. L. Sanderson, L. Reshitnyk, J. K. O'Leary, P. M. Kiffney, M. Hessing-Lewis, T. G. Gerwing, C. A. Endris, W. B. Chesney, K. M. Beheshti, F. L. Beaty Oct 2023

Decades Of Eelgrass Meadow Dynamics Across The Northeast Pacific Support Seascape-Scale Conservation, S. H. Munsch, Ryan K. Walter, B. L. Sanderson, L. Reshitnyk, J. K. O'Leary, P. M. Kiffney, M. Hessing-Lewis, T. G. Gerwing, C. A. Endris, W. B. Chesney, K. M. Beheshti, F. L. Beaty

Physics

Eelgrass meadows provide vital nearshore habitats and ecosystem services, but they have declined from human stressors and conservation efforts are now widespread. Dynamic ecosystems like eelgrass meadows naturally rearrange as disturbance and recruitment unfold across seascapes. However, some decisions that protect eelgrass only consider extant meadows, thus ignoring the potential for change. Here, we report decades of eelgrass dynamics observed across the northeast Pacific. Our observations support conservation expanded to the seascape scale, which includes potentially inhabitable areas along with extant meadows. We found that total seascape meadow area changed over time, and changes within seascapes were often asynchronous. Some …


Signatures Of Feedback In The Spectacular Extended Emission Region Of Ngc 5972, Thomas Harvey, W. Peter Maksym, William Keel, Michael Koss, Vardha N. Bennert, S. Drew Chojnowski, Ezequiel Treister, Carolina Finlez, Chris J. Lintott, Alexei Moiseev, Brooke D. Simmons, Lia F. Sartori, Megan Urry Oct 2023

Signatures Of Feedback In The Spectacular Extended Emission Region Of Ngc 5972, Thomas Harvey, W. Peter Maksym, William Keel, Michael Koss, Vardha N. Bennert, S. Drew Chojnowski, Ezequiel Treister, Carolina Finlez, Chris J. Lintott, Alexei Moiseev, Brooke D. Simmons, Lia F. Sartori, Megan Urry

Physics

We present Chandra X-ray Observatory observations and Space Telescope Imaging Spectrograph spectra of NGC 5972, one of the 19 ‘Voorwerpjes’ galaxies. This galaxy contains an extended emission-line region (EELR) and an arcsecond scale nuclear bubble. NGC 5972 is a faded active galactic nucleus (AGN), with EELR luminosity suggesting a 2.1 dex decrease in Lbol in the last ∼5 ×104 yr. We investigate the role of AGN feedback in exciting the EELR and bubble given the long-term variability and potential accretion state changes. We detect broad-band (0.3–8 keV) X-ray emission in the near-nuclear regions, coincident with the [O III …


The Seoul National University Agn Monitoring Project. Iv. Hα Reverberation Mapping Of Six Agns And The Hα Size–Luminosity Relation, Hojin Cho, Jong-Hak Woo, Shu Wang, Donghoon Son, Jaejin Shin, Suvendu Rakshit, Aaron J. Barth, Vardha N. Bennert, Elena Gallo, Edmund Hodges-Kluck, Tommaso Treu, Hyun-Ji Bae, Wanjin Cho, Adi Foord, Jaehyuk Geum, Yashashree Jadhav, Yiseul Jeon, Kyle M. Kabasares, Daeun Kang, Wonseok Kang, Changseok Kim, Donghwa Kim, Minjin Kim, Taewoo Kim, Huynh Anh N. Lee, Matthew A. Malkan, Amit Kumar Mandal, Daeseong Park, Hyun-Il Sung, Vivian U, Peter R. Williams Aug 2023

The Seoul National University Agn Monitoring Project. Iv. Hα Reverberation Mapping Of Six Agns And The Hα Size–Luminosity Relation, Hojin Cho, Jong-Hak Woo, Shu Wang, Donghoon Son, Jaejin Shin, Suvendu Rakshit, Aaron J. Barth, Vardha N. Bennert, Elena Gallo, Edmund Hodges-Kluck, Tommaso Treu, Hyun-Ji Bae, Wanjin Cho, Adi Foord, Jaehyuk Geum, Yashashree Jadhav, Yiseul Jeon, Kyle M. Kabasares, Daeun Kang, Wonseok Kang, Changseok Kim, Donghwa Kim, Minjin Kim, Taewoo Kim, Huynh Anh N. Lee, Matthew A. Malkan, Amit Kumar Mandal, Daeseong Park, Hyun-Il Sung, Vivian U, Peter R. Williams

Physics

The broad-line region (BLR) size–luminosity relation has paramount importance for estimating the mass of black holes in active galactic nuclei (AGNs). Traditionally, the size of the Hβ BLR is often estimated from the optical continuum luminosity at 5100 Å, while the size of the Hα BLR and its correlation with the luminosity is much less constrained. As a part of the Seoul National University AGN Monitoring Project, which provides 6 yr photometric and spectroscopic monitoring data, we present our measurements of the Hα lags of high-luminosity AGNs. Combined with the measurements for 42 AGNs from the literature, …


Effects Of Basin-Scale Climate Modes And Upwelling On Nearshore Marine Heatwaves And Cold Spells In The California Current, Michael Dalsin, Ryan K. Walter, Piero L. F. Mazzini Jul 2023

Effects Of Basin-Scale Climate Modes And Upwelling On Nearshore Marine Heatwaves And Cold Spells In The California Current, Michael Dalsin, Ryan K. Walter, Piero L. F. Mazzini

Physics

Marine heatwaves and cold spells (MHWs/MCSs) have been observed to be increasing globally in frequency and intensity based on satellite remote sensing and continue to pose a major threat to marine ecosystems worldwide. Despite this, there are limited in-situ based observational studies in the very shallow nearshore region, particularly in Eastern Boundary Current Upwelling Systems (EBUS). We analyzed a unique dataset collected in shallow waters along central California spanning more than four decades (1978–2020) and assessed links with basin-scale climate modes [Pacific Decadal Oscillation (PDO) and El Niño (MEI)] and regional-scale wind-driven upwelling. We found no significant increase/decrease in MHW/MCS …


Optimization Of Flagellar Locomotion In The Low Reynolds Number Regime, Aidan M. Trodden, Aidan M. Trodden Jun 2023

Optimization Of Flagellar Locomotion In The Low Reynolds Number Regime, Aidan M. Trodden, Aidan M. Trodden

Physics

This report investigates the computational and theoretical techniques - modeled by E. Lauga and C. Eloy - used to optimize the shape of an activated flagellum for enhanced cell motility. Cell motility is ubiquitous and has a large affect on biological systems such as marine life ecosystems, reproduction, and infection. The physical principles governing flagellar propulsion are explored using computational fluid dynamics simulations, mathematical modeling, and the sequential quadratic programming (SQP) optimization algorithm. Through iterative refinement, we can identify optimized flagellar shapes that would minimize the energetic cost dependent on a single dimensionless sperm numbers (Sp). The computation of the …


Optimizing Solid Thermal Storage In Insulated Solar Electric Cookers, Stefan Avramov Jun 2023

Optimizing Solid Thermal Storage In Insulated Solar Electric Cookers, Stefan Avramov

Physics

Insulated Solar Electric Cookers, more commonly known by their acronym ISECookers, are an alternative to biomass cooking. The ISECooker in its simplest form is a solar panel connected to a heating element, in contact with a cooking pot in an insulated chamber. An aluminum puck can be heated as solid thermal storage (STS) for increased power and night time cooking. Power was limited to about 500 W by the interface between the STS and cookpot. Powdered graphite and silver were separately applied to increase thermal flow. However, the powdered graphite decreased the thermal flow, while powdered silver decreased the temperature …


Diffusion-Driven Aggregation Of Particles In Quasi-2d Membranes, Oscar Gullickson Rausis Jun 2023

Diffusion-Driven Aggregation Of Particles In Quasi-2d Membranes, Oscar Gullickson Rausis

Physics

Many biological membranes can be modeled as two-dimensional (2D) viscous fluid sheets surrounded by three-dimensional (3D) fluids of different viscosity. Such membranes are dubbed quasi-2D as they exhibit properties of both 2D and 3D fluids. The Saffman length is a parameter that describes the energy exchange between the membrane and bulk fluids and controls the cross-over from 2D to 3D hydrodynamics. We aim to model diffusion-driven aggregation of particles embedded in a quasi-2D membrane. It is known that hydrodynamic interactions between solute particles significantly reduce their aggregation rate in 3D fluids. It is expected that in quasi-2D membranes the reduction …


A Monte-Carlo Simulation Of Gamma Rays In A Sodium Iodide Detector, Ben Kessler Jun 2023

A Monte-Carlo Simulation Of Gamma Rays In A Sodium Iodide Detector, Ben Kessler

Physics

Gamma rays principally interact with matter through Compton scattering, photoelectric effect, pair production, and triplet production. The focus of this simulation is to study the theoretical energy spectrum created by gamma rays from a Cesium-137 source, which produces gamma photons with an energy of 0.662 MeV. At this energy level, most interactions are results of Compton scatters and the photoelectric effect. Therefore, this simulation only models those two effects on gamma rays. Using Monte Carlo methods and the Metropolis algorithm to sample the probability distributions of the two effects allowed for the simulation of gamma rays in a Sodium Iodide …


Flushing Time Variability In A Short, Low-Inflow Estuary, Mohsen Taherkhani, Sean Vitousek, Ryan K. Walter, Jennifer O'Leary, Amid P. Khodadoust May 2023

Flushing Time Variability In A Short, Low-Inflow Estuary, Mohsen Taherkhani, Sean Vitousek, Ryan K. Walter, Jennifer O'Leary, Amid P. Khodadoust

Physics

Flushing time, the time scale for exchange and mixing between embayed and oceanic waters in an estuary, plays an integral role in determining water quality and aquatic ecosystem health. Here, we investigated the spatiotemporal variability of flushing times throughout Morro Bay, a short, low-inflow estuary (LIE) on the California coast, using a calibrated and validated hydrodynamic model (Delft3D). Morro Bay has historically supported an extensive eelgrass (Zostera marina) habitat, which declined substantially from 139 to 5.4 ha during 2007–2017. Eelgrass decline motivated the current research into the role of changing bed roughness and oceanic drivers (i.e., tide and …


What Does The Geometry Of The Hβblr Depend On?, Lizvette Villafaña, Peter R. Williams, Tommaso Treu, Brendon J. Brewer, Aaron J. Barth, Vivian U, Vardha N. Bennert, Hengxiao Guo, Misty C. Bentz, Gabriela Canalizo, Alexei V. Filippenko, Elinor Gates, Michael D. Joner, Matthew A. Malkan, Jong-Hak Woo, Bela Abolfathi, Thomas Bohn, K. Azalee Bostroem, Goni Halevi, Carol E. Hood, J. Chuck Horst, Maxime De Kouchkovsky, Benjamin Kuhn, Douglas C. Leonard, Raúl Michel, Melanie Kae B. Olaes, Daeseong Park, Jordan N. Runco, Remington O. Sexton, Isaac Shivvers, Chance L. Spencer, Benjamin E. Stahl, Samantha Stegman, Jonelle L. Walsh, Weikang Zheng May 2023

What Does The Geometry Of The Hβblr Depend On?, Lizvette Villafaña, Peter R. Williams, Tommaso Treu, Brendon J. Brewer, Aaron J. Barth, Vivian U, Vardha N. Bennert, Hengxiao Guo, Misty C. Bentz, Gabriela Canalizo, Alexei V. Filippenko, Elinor Gates, Michael D. Joner, Matthew A. Malkan, Jong-Hak Woo, Bela Abolfathi, Thomas Bohn, K. Azalee Bostroem, Goni Halevi, Carol E. Hood, J. Chuck Horst, Maxime De Kouchkovsky, Benjamin Kuhn, Douglas C. Leonard, Raúl Michel, Melanie Kae B. Olaes, Daeseong Park, Jordan N. Runco, Remington O. Sexton, Isaac Shivvers, Chance L. Spencer, Benjamin E. Stahl, Samantha Stegman, Jonelle L. Walsh, Weikang Zheng

Physics

We combine our dynamical modeling black-hole mass measurements from the Lick AGN Monitoring Project 2016 sample with measured cross-correlation time lags and line widths to recover individual scale factors, f, used in traditional reverberation-mapping analyses. We extend our sample by including prior results from Code for AGN Reverberation and Modeling of Emission Lines (CARAMEL) studies that have utilized our methods. Aiming to improve the precision of black-hole mass estimates, as well as uncover any regularities in the behavior of the broad-line region (BLR), we search for correlations between f and other AGN/BLR parameters. We find (i) evidence for a …


Tdcosmo - Xii. Improved Hubble Constant Measurement From Lensing Time Delays Using Spatially Resolved Stellar Kinematics Of The Lens Galaxy, Anowar J. Shajib, Pritom Mozumdar, Geoff C.-F. Chen, Tommaso Treu, Michele Cappellari, Shawn Knabel, Sherry H. Suyu, Vardha N. Bennert, Joshua A. Frieman, Dominique Sluse, Simon Birrer, Frederic Courbin, Christopher D. Fassnacht, Lizvette Villafaña, Peter R. Williams May 2023

Tdcosmo - Xii. Improved Hubble Constant Measurement From Lensing Time Delays Using Spatially Resolved Stellar Kinematics Of The Lens Galaxy, Anowar J. Shajib, Pritom Mozumdar, Geoff C.-F. Chen, Tommaso Treu, Michele Cappellari, Shawn Knabel, Sherry H. Suyu, Vardha N. Bennert, Joshua A. Frieman, Dominique Sluse, Simon Birrer, Frederic Courbin, Christopher D. Fassnacht, Lizvette Villafaña, Peter R. Williams

Physics

Strong-lensing time delays enable the measurement of the Hubble constant (H0) independently of other traditional methods. The main limitation to the precision of time-delay cosmography is mass-sheet degeneracy (MSD). Some of the previous TDCOSMO analyses broke the MSD by making standard assumptions about the mass density profile of the lens galaxy, reaching 2% precision from seven lenses. However, this approach could potentially bias the H0 measurement or underestimate the errors. For this work, we broke the MSD for the first time using spatially resolved kinematics of the lens galaxy in RXJ1131−1231 obtained from the Keck Cosmic …


The Nature Of Lobal Qsos. Ii. Hst/Wfc3 Observations Reveal Host Galaxies Dominated By Mergers, Mariana S. Lazarova, Gabriela Canalizo, Mark Lacy, Wyatt Behn, Kaitlyn Raub, Vardha N. Bennert, Duncan Farrah May 2023

The Nature Of Lobal Qsos. Ii. Hst/Wfc3 Observations Reveal Host Galaxies Dominated By Mergers, Mariana S. Lazarova, Gabriela Canalizo, Mark Lacy, Wyatt Behn, Kaitlyn Raub, Vardha N. Bennert, Duncan Farrah

Physics

Low-ionization broad absorption line QSOs (LoBALs) are suspected to be merging systems in which extreme, active galactic nucleus-driven outflows have been triggered. Whether or not LoBALs are uniquely associated with mergers, however, has yet to be established. To characterize the morphologies of LoBALs, we present the first high-resolution morphological analysis of a volume-limited sample of 22 Sloan Digital Sky Survey (SDSS)-selected LoBALs at 0.5 < z < 0.6 from Hubble Space Telescope Wide Field Camera 3 observations. Host galaxies are resolved in 86% of the systems in F125W, which is sensitive to old stellar populations, while only 18% are detected in F475W, which traces young, unobscured stellar populations. Signs of recent or ongoing tidal interaction are present in 45%–64% of the hosts, including double nuclei, tidal tails, bridges, plumes, shells, and extended debris. Ongoing interaction with a companion is apparent in 27%−41% of the LoBALs, with as much as 1/3 of the sample representing late-stage mergers at projected nuclear separations <10 kpc. Detailed surface brightness modeling indicates that 41% of the hosts are bulge dominated while only 18% are disks. We discuss trends in various properties as a function of merger stage and parametric morphology. Notably, mergers are associated with slower, dustier winds than those seen in undisturbed/unresolved hosts. Our results favor an evolutionary scenario in which quasar-level accretion during various merger stages is associated with the observed outflows in low-z LoBALs. We discuss differences between LoBALs and FeLoBALs and show that selection via the traditional balnicity index would have excluded all but one of the mergers.


Application Of Deep Learning For Classification Of Intertidal Eelgrass From Drone-Acquired Imagery, Krti Tallam, Nam Nguyen, Jonathan Ventura, Andrew G. Fricker, Sadie Calhoun, Jennifer O’Leary, Mauriça Fitzgibbons, Ian C. Robbins, Ryan K. Walter Apr 2023

Application Of Deep Learning For Classification Of Intertidal Eelgrass From Drone-Acquired Imagery, Krti Tallam, Nam Nguyen, Jonathan Ventura, Andrew G. Fricker, Sadie Calhoun, Jennifer O’Leary, Mauriça Fitzgibbons, Ian C. Robbins, Ryan K. Walter

Physics

Shallow estuarine habitats are globally undergoing rapid changes due to climate change and anthropogenic influences, resulting in spatiotemporal shifts in distribution and habitat extent. Yet, scientists and managers do not always have rapidly available data to track habitat changes in real-time. In this study, we apply a novel and a state-of-the-art image segmentation machine learning technique (DeepLab) to two years of high-resolution drone-based imagery of a marine flowering plant species (eelgrass, a temperate seagrass). We apply the model to eelgrass (Zostera marina) meadows in the Morro Bay estuary, California, an estuary that has undergone large eelgrass declines and the subsequent …


Northeast Pacific Eelgrass Dynamics: Interannual Expansion Distances And Meadow Area Variation Over Time, Stuart H. Munsch, Fiona L. Beaty, Kathryn M. Beheshti, W. Bryant Chesney, Charlie A. Endris, Travis G. Gerwing, Margot Hessing-Lewis, Peter M. Kiffney, Jennifer K. O’Leary, Luba Reshitnyk, Beth L. Sanderson, Ryan K. Walter Feb 2023

Northeast Pacific Eelgrass Dynamics: Interannual Expansion Distances And Meadow Area Variation Over Time, Stuart H. Munsch, Fiona L. Beaty, Kathryn M. Beheshti, W. Bryant Chesney, Charlie A. Endris, Travis G. Gerwing, Margot Hessing-Lewis, Peter M. Kiffney, Jennifer K. O’Leary, Luba Reshitnyk, Beth L. Sanderson, Ryan K. Walter

Physics

Ecosystems constantly change, yet managers often lack information to move beyond static habitat assumptions. As human impacts and geographic information systems advance, it is important and feasible to quantify past habitat boundary shifts to inform management decisions (e.g. protective perimeters) robust to near-term habitat changes. This is the case in eelgrass (Zostera spp.), an ecosystem engineer that forms dynamic, often protected meadows. Practitioners protect areas to avoid human stress to eelgrass, but they can lack quantitative descriptions of the near-term potential for eelgrass meadows to shift into unprotected areas. Here, we quantified interannual eelgrass meadow boundary shifts within 23 sites …


Spatial Distribution Of Seawater Carbonate Chemistry And Hydrodynamic Controls In A Low-Inflow Estuary, Sarah E. Bartoloni, Ryan K. Walter, Sydney N. Wewerka, Jolie Higgins, Jennifer K. O'Leary, Emily E. Bockmon Feb 2023

Spatial Distribution Of Seawater Carbonate Chemistry And Hydrodynamic Controls In A Low-Inflow Estuary, Sarah E. Bartoloni, Ryan K. Walter, Sydney N. Wewerka, Jolie Higgins, Jennifer K. O'Leary, Emily E. Bockmon

Physics

Coastal and estuarine systems play an important role in the global carbon cycle and often have complex carbonate chemistry dynamics due to a multitude of biogeochemical and physical drivers. Compared to classic estuaries, mechanisms driving the distribution of carbonate parameters in low-inflow estuaries are understudied. The spatial distribution of carbonate chemistry and hydrodynamic parameters were characterized in Morro Bay, a short and seasonally hypersaline estuary on the Central California Coast, during the dry, low-inflow season to better understand in situ modifications. Sampling transects were completed in the main channel in June, August, and September of 2018, bracketing both a high …


The Close Agn Reference Survey (Cars): A Parsec-Scale Multi-Phase Outflow In The Super-Eddington Nls1 Mrk 1044, N. Winkel, B. Husemann, M. Singha, V. N. Bennert, F. Combes, T. A. Davis, M. Gaspari, K. Jahnke, R. Mcelroy, C. P. O'Dea, M. A. Pérez-Torres Jan 2023

The Close Agn Reference Survey (Cars): A Parsec-Scale Multi-Phase Outflow In The Super-Eddington Nls1 Mrk 1044, N. Winkel, B. Husemann, M. Singha, V. N. Bennert, F. Combes, T. A. Davis, M. Gaspari, K. Jahnke, R. Mcelroy, C. P. O'Dea, M. A. Pérez-Torres

Physics

Context. The interaction between active galactic nuclei (AGNs) and their host galaxies is scarcely resolved. Narrow-line Seyfert 1 (NLS1) galaxies are believed to represent AGN at early stages of their evolution and to allow one to observe feeding and feedback processes at high black hole accretion rates.

Aims. We aim to constrain the properties of the ionised gas outflow in Mrk 1044, a nearby super-Eddington accreting NLS1. Based on the outflow energetics and the associated timescales, we estimate the outflow’s future impact on the ongoing host galaxy star formation on different spatial scales.

Methods. We applied a spectroastrometric analysis to …


Building Structures From Mycelium, Noah M. Brown Dec 2022

Building Structures From Mycelium, Noah M. Brown

Physics

The purpose of this project was to develop a method for creating bricks from mycelium and agricultural waste. The bulk of the research happened in two parts, the first part being a period in which different substrates, strains, and methods were used build the bricks. This research took place in San Luis Obispo and was aided by a group of students in PSC392 under Dr. Pete Schwartz in early 2022. After developing a method for constructing these bricks, the research was moved to St. Thomas, Jamaica, in collaboration with an ecovillage called The Source Farm from July to September. The …


Thermal Degradation Of Erythritol, Sudheendra Gamoji Nov 2022

Thermal Degradation Of Erythritol, Sudheendra Gamoji

Physics

The Insulated Solar Electric Cooker (ISEC) is a double walled Aluminum pot with a resistive heater directly connected to a solar panel whose goal is to create and disseminate cheap solar cookers in rural areas that primarily rely on biomass for cooking. Phase Change Materials (PCMs) like Erythritol, a sugar substitute, take a tremendous amount of energy to melt, and when they solidify they release the energy. Through the use of PCMs, the ISECs will produce enough heat to cook food even after the sun sets. However, PCMs like Erythritol degrade over repeated heat exposure, so the purpose of this …


Seasonal Controls On Nearshore Dissolved Oxygen Variability And Hypoxia In A Coastal Embayment, Ryan K. Walter, Stephen A. Huie, Jon Christian P. Abraham, Alexis Pasulka, Kristen A. Davis, Thomas P. Connolly, Piero L.F. Mazzini, Ian Robbins Oct 2022

Seasonal Controls On Nearshore Dissolved Oxygen Variability And Hypoxia In A Coastal Embayment, Ryan K. Walter, Stephen A. Huie, Jon Christian P. Abraham, Alexis Pasulka, Kristen A. Davis, Thomas P. Connolly, Piero L.F. Mazzini, Ian Robbins

Physics

Declining dissolved oxygen (DO) is emerging as an increasingly important stressor in nearshore ecosystems, and there is a growing need to better understand DO dynamics and hypoxia risk in this highly variable environment. In this study, we collected data from monthly cruises on the inner shelf, continuous nearshore moorings inside and outside a small coastal upwelling embayment (San Luis Obispo Bay in Central California), and weekly phytoplankton measurements inside the bay during the upwelling season. Nearshore DO was generally dominated by low-frequency synoptic variability, with increased DO variance near the surface relative to the bottom and inside the bay compared …


Developing Positive Thermal Coefficient (Ptc) Heaters For Solar Electric Cooking, Katarina Ivana Brekalo, Andrew Shepherd Sep 2022

Developing Positive Thermal Coefficient (Ptc) Heaters For Solar Electric Cooking, Katarina Ivana Brekalo, Andrew Shepherd

Physics

Positive Thermal Coefficients, PTCs, are materials that abruptly change in resistance in response to changes in temperature. The purpose of this experiment is to explore the viability of using the switching type ceramic PTC thermistor as a replacement for current resistive heaters. These types of PTCs have a nonlinear change in resistance with increases in temperature. This device will be used as a temperature-controlling heating element intended to power an Insulated Solar Electric Cooker (ISEC). The ISEC is designed to cook meals throughout the day for impacted communities as an alternative cooking method that doesn’t require biofuel as an energy …


An Inexpensive Maximum Power Point Tracking System For An Insulated Solar Electric Cooker Using An Off-The-Shelf Buck Converter, Andrew A. Perez Sep 2022

An Inexpensive Maximum Power Point Tracking System For An Insulated Solar Electric Cooker Using An Off-The-Shelf Buck Converter, Andrew A. Perez

Physics

A specialized control circuit using an off-the-shelf buck converter is built for an Insulated Solar Electric Cooker (ISEC). Cost and efficient power delivery are the focus. An ISEC is synonymous to a direct load heat resistor, allowing a specific maximum power point tracking (MPPT) algorithm and fewer components. Only a microcontroller, voltage sensor, and digital-to-analog converter are used with the buck converter to maximize the power delivered by a 100W solar panel for the 3.3Ω load.


Spatial And Temporal Characteristics Of California Commercial Fisheries From 2005 To 2019 And Potential Overlap With Offshore Wind Energy Development, Yi-Hui Wang, Ryan K. Walter, Crow White, Benjamin I. Ruttenberg Aug 2022

Spatial And Temporal Characteristics Of California Commercial Fisheries From 2005 To 2019 And Potential Overlap With Offshore Wind Energy Development, Yi-Hui Wang, Ryan K. Walter, Crow White, Benjamin I. Ruttenberg

Physics

As climate change accelerates and fisheries management continues to evolve, California's commercial fisheries are changing. To improve the understanding of recent California fisheries dynamics, we compiled and analyzed commercial landings receipts to characterize temporal and spatial variation in landing and value of key fisheries groups within the exclusive economic zone across the state from 2005 to 2019. We found that California fisheries continue a shift first observed in the 1980s from higher‐biomass, lower‐value species, such as coastal pelagic species and market squid, toward lower‐biomass, higher‐value species, such as Dungeness crab Cancer magister and groundfish. Over the 15‐year time series analyzed, …


The Close Agn Reference Survey (Cars): Tracing The Circumnuclear Star Formation In The Super-Eddington Nls1 Mrk 1044, N. Winkel, T. A. Davis, I. Smirnova-Pinchukova, V. N. Bennert, F. Combes, M. Gaspari, K. Jahnke, J. Neumann, C. P. O'Dea, M. Pérez-Torres, M. Singha, G. R. Tremblay, H. W. Rix Jul 2022

The Close Agn Reference Survey (Cars): Tracing The Circumnuclear Star Formation In The Super-Eddington Nls1 Mrk 1044, N. Winkel, T. A. Davis, I. Smirnova-Pinchukova, V. N. Bennert, F. Combes, M. Gaspari, K. Jahnke, J. Neumann, C. P. O'Dea, M. Pérez-Torres, M. Singha, G. R. Tremblay, H. W. Rix

Physics

Context. The host galaxy conditions for rapid supermassive black hole growth are poorly understood. Narrow-line Seyfert 1 (NLS1) galaxies often exhibit high accretion rates and are hypothesized to be prototypes of active galactic nuclei (AGN) at an early stage of their evolution.

Aims. We present adaptive optics (AO) assisted VLT MUSE NFM observations of Mrk 1044, the nearest super-Eddington accreting NLS1. Together with archival MUSE WFM data, we aim to understand the host galaxy processes that drive Mrk 1044’s black hole accretion.

Methods. We extracted the faint stellar continuum emission from the AGN-deblended host and performed spatially resolved emission line …


Solid Thermal Storage As An Energy Storage Device In Insulated Solar Electric Cookers: Thermal Modeling And Experiment, Michael Antonio Fernandez Jun 2022

Solid Thermal Storage As An Energy Storage Device In Insulated Solar Electric Cookers: Thermal Modeling And Experiment, Michael Antonio Fernandez

Physics

The use of solid thermal storage (STS) as an energy storage device in insulated solar electric cookers (ISEC) was explored using a thermal simulation before retrofitting an existing cooker without energy storage and testing it under several conditions. STS sizing, material selection, and geometry were examined from both theoretical and practical perspectives and re-examined following experimental results. Characterization of the system’s thermal interfaces and methods to improve their thermal conductivities were investigated resulting in several performance enhancements to the system.