Physical Sciences and Mathematics Commons^™

Machine Learning Prediction Of Hea Properties, Nicholas J. Beaver, Nathaniel Melisso, Travis Murphy

College of Engineering Summer Undergraduate Research Program

High-entropy alloys (HEA) are a very new development in the field of metallurgical materials. They are made up of multiple principle atoms unlike traditional alloys, which contributes to their high configurational entropy. The microstructure and properties of HEAs are are not well predicted with the models developed for more common engineering alloys, and there is not enough data available on HEAs to fully represent the complex behavior of these alloys. To that end, we explore how the use of machine learning models can be used to model the complex, high dimensional behavior in the HEA composition space. Based on our …

Dei: Exploring Academic Reflections Using Natural Language Processing To Create A Roadmap Of Student Success And Foster Inclusive Engineering Education, Rajvir H. Vyas, Nidhi Raviprasad

College of Engineering Summer Undergraduate Research Program

Every year, the College of Engineering (CENG) students and faculty reach out to admitted students through “Text-a-Thon” programs to answer their questions about being a student at Cal Poly. In order to improve CENG outreach efforts, we analyzed these text conversations to predict the likelihood of an admitted student accepting an offer of admission from Cal Poly. Through our research, we discovered key factors that play a role in a student committing to Cal Poly through data-based insights. Additionally, we successfully used a human-on-the-loop system to help create Machine Learning (ML) models that predict satisfaction of response by way of …

Integrating Human Expert Knowledge With Openai And Chatgpt: A Secure And Privacy-Enabled Knowledge Acquisition Approach, Ben Phillips

College of Engineering Summer Undergraduate Research Program

Advanced Large Language Models (LLMs) struggle to produce accurate results and preserve user privacy for use cases involving domain-specific knowledge. A privacy-preserving approach for leveraging LLM capabilities on domain-specific knowledge could greatly expand the use cases of LLMs in a variety of disciplines and industries. This project explores a method for acquiring domain-specific knowledge for use with GPT3 while protecting sensitive user information with ML-based text-sanitization.

Development Of User Interface And Testing Harness, Jacob Amezquita, William Albertini

College of Engineering Summer Undergraduate Research Program

No abstract provided.

Ai For Search And Rescue - Locating A Missing Person, David Hernandez, Sai Rama Balakrishnan, Timmy Chin, Aditya Manikonda, Vasanth Pugalenthi

College of Engineering Summer Undergraduate Research Program

Building on the work done initially as a SURP 2021 project and continued through 2021-23, the focus for this summer project will be on the use of computer technology for locating a missing person. Over the last year, we developed the digital equivalents of about 30 paper-based S&R forms and the infrastructure to collect the respective information. In their current use, these paper forms are filled out by search teams, collected in a command post, and reviewed by search coordinators. This process is time-consuming, prone to errors and loss of information, and relies heavily on the experience, skills, and mental …

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 L_bol 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 …

Ethics And Social Justice For Ai In Data Science, Arya Ramchander, Kylene Nicole Landenberger

College of Engineering Summer Undergraduate Research Program

The advances of AI raise several critical questions about human values and ethics, highlighting the need for researchers and developers to consider the ethical implications and the risks of neglecting them. In the past few years, student researchers have developed an AI model that allows users to test their surveys for possible breaches of subject confidentiality. This allows the users to gauge the ethicality of their proposal. This summer, we have expanded on this research and launched an interactive model for students and researches to assess their current work for ethical and social justice implications. Using Langchain and Figma, we …

Exploring Approaches To Engage K-12 Students In Learning Computational Thinking Using Collaborative Robots, Zoila Anuri Kanu

College of Engineering Summer Undergraduate Research Program

Minority students are largely underrepresented in the STEM field. The goal for this project was to develop a program which promotes the inclusion of computation skills among students and help them work collaboratively with the use of human – robot interaction. Robots are such a strong tool that can be used to enhance computational thinking and engage students towards a technical field. Through workshops and readings about computational thinking we worked on building a block-based program that introduces the uses of robots as teaching tool for computational thinking.

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, …

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 …

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 …

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.

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 …

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 …

The Close Agn Reference Survey (Cars): Ifu Survey Data And The Bh Mass Dependence Of Long-Term Agn Variability, B. Husemann, M. Singha, J. Scharwächter, R. Mcelroy, J. Neumann, I. Smirnova-Pinchukova, T. Urrutia, S. A. Baum, V. N. Bennert, F. Combes, S. M. Croom, T. A. Davis, Y. Fournier, A. Galkin, M. Gaspari, H. Enke, M. Krumpe, C. P. O'Dea, M. Pérez-Torres, T. Rose, G. R. Tremblay, C. J. Walcher

Physics

Context. Active galactic nuclei (AGN) are thought to be intimately connected with their host galaxies through feeding and feedback processes. A strong coupling is predicted and supported by cosmological simulations of galaxy formation, but the details of the physical mechanisms are still observationally unconstrained.

Aims. Galaxies are complex systems of stars and a multiphase interstellar medium (ISM). A spatially resolved multiwavelength survey is required to map the interaction of AGN with their host galaxies on different spatial scales and different phases of the ISM. The goal of the Close AGN Reference Survey (CARS) is to obtain the necessary spatially resolved …

The Lick Agn Monitoring Project 2016: Velocity-Resolved Hβ Lags In Luminous Seyfert Galaxies, Vivian U, Aaron J. Barth, H. Alexander Vogler, Hengxiao Guo, Tommaso Treu, Vardha N. Bennert, Gabriela Canalizo, Alexei V. Filippenko, Elinor Gates, Frederick Hamann, Michael D. Joner, Matthew A. Malkan, Anna Pancoast, Peter R. Williams, Jong-Hak Woo, Bela Abolfathi, L. E. Abramson, Stephen F. Armen, Hyun-Jin Bae, Thomas Bohn, Benjamin D. Boizelle, Azalee Bostroem, Andrew Brandel, Thomas G. Brink, Sanyum Channa, M. C. Cooper, Maren Cosens, Edward Donohue, Sean P. Fillingham, Diego González-Buitrago, Goni Halevi, Andrew Halle, Carol E. Hood, Keith Horne, J. Chuck Horst, Maxime De Kouchkovsky, Benjamin Kuhn, Sahana Kumar, Douglas C. Leonard, Donald Loveland, Christina Manzano-King, Ian Mchardy, Raúl Michel, Melanie Kae B. Olaes, Daeseong Park, Songyoun Park, Liuyi Pei, Timothy W. Ross, Jordan N. Runco, Jenna Samuel, Javier Sánchez, Bryan Scott, Remington O. Sexton, Jaejin Shin, Isaac Shivvers, Chance L. Spencer, Benjamin E. Stahl, Samantha Stegman, Isak Stomberg, Stefano Valenti, L. Villafaña, Jonelle L. Walsh, Heechan Yuk, Weikang Zheng

Physics

We carried out spectroscopic monitoring of 21 low-redshift Seyfert 1 galaxies using the Kast double spectrograph on the 3 m Shane telescope at Lick Observatory from 2016 April to 2017 May. Targeting active galactic nuclei (AGNs) with luminosities of λLλ(5100 Å) ≈ 1044 erg s−1 and predicted Hβ lags of ∼20–30 days or black hole masses of 107–108.5 M⊙, our campaign probes luminosity-dependent trends in broad-line region (BLR) structure and dynamics as well as to improve calibrations for single-epoch estimates of quasar black hole masses. Here we present the first results from the campaign, including …

The Lick Agn Monitoring Project 2016: Velocity-Resolved Hβ Lags In Luminous Seyfert Galaxies, Vivian U, Aaron J. Barth, H. Alexander Vogler, Hengxiao Guo, Tommaso Treu, Vardha N. Bennert, Gabriela Canalizo, Alexei V. Filippenko, Elinor Gates, Frederick Hamann, Michael D. Joner, Matthew A. Malkan, Anna Pancoast, Peter R. Williams, Jong-Hak Woo, Bela Abolfathi, L. E. Abramson, Stephen F. Armen, Hyun-Jin Bae, Thomas Bohn, Benjamin D. Boizelle, Azalee Bostroem, Andrew Brandel, Thomas G. Brink, Sanyum Channa, M. C. Cooper, Maren Cosens, Edward Donohue, Sean P. Fillingham, Diego González-Buitrago, Goni Halevi, Andrew Halle, Carole E. Hood, Keith Horne, J. Chuck Horst, Maxime De Kouchkovsky, Benjamin Kuhn, Sahana Kumar, Douglas C. Leonard, Donald Loveland, Christina Manzano-King, Ian Mchardy, Raúl Michel, Melanie Kae B. Olaes, Daeseong Park, Songyoun Park, Liuyi Pei, Timothy W. Ross, Jordan N. Runco, Jenna Samuel, Javier Sánchez, Bryan Scott, Remington O. Sexton, Jaejin Shin, Isaac Shivvers, Chance L. Spencer, Benjamin E. Stahl, Samantha Stegman, Isak Stomberg, Stefano Valenti, L. Villafaña, Jonelle L. Walsh, Heechan Yuk, Weikang Zheng

Physics

We carried out spectroscopic monitoring of 21 low-redshift Seyfert 1 galaxies using the Kast double spectrograph on the 3 m Shane telescope at Lick Observatory from 2016 April to 2017 May. Targeting active galactic nuclei (AGNs) with luminosities of λLλ(5100 Å) ≈ 1044 erg s−1 and predicted Hβ lags of ∼20–30 days or black hole masses of 107–108.5 M⊙, our campaign probes luminosity-dependent trends in broad-line region (BLR) structure and dynamics as well as to improve calibrations for single-epoch estimates of quasar black hole masses. Here we present the first results from the campaign, including …

Hα Reverberation Mapping Of The Intermediate-Mass Active Galactic Nucleus In Ngc 4395, Hojin Cho, Jong-Hak Woo, Tommaso Treu, Peter R. Williams, Stephen F. Armen, Aaron J. Barth, Vardha N. Bennert, Wanjin Cho, Alexei V. Filippenko, Elena Gallo, Jaehyuk Geum, Diego González-Buitrago, Kayhan Gültekin, Edmund Hodges-Kluck, John C. Horst, Seong Hyeon Hwang, Wonseok Kang, Minjin Kim, Taewoo Kim, Douglas C. Leonard, Matthew A. Malkan, Raymond P. Remigio, David J. Sand, Jaejin Shin, Donghoon Son, Hyun-Il Sung, Vivian U

Physics

We present the results of a high-cadence spectroscopic and imaging monitoring campaign of the active galactic nucleus (AGN) of NGC 4395. High signal-to-noise-ratio spectra were obtained at the Gemini-N 8 m telescope using the GMOS integral field spectrograph (IFS) on 2019 March 7 and at the Keck I 10 m telescope using the Low-Resolution Imaging Spectrometer with slit masks on 2019 March 3 and April 2. Photometric data were obtained with a number of 1 m-class telescopes during the same nights. The narrow-line region (NLR) is spatially resolved; therefore, its variable contributions to the slit spectra make the standard procedure …

A Local Baseline Of The Black Hole Mass Scaling Relations For Active Galaxies. Iv. Correlations Between MBh And Host Galaxy Σ, Stellar Mass, And Luminosity, Vardha N. Bennert, Tommaso Treu, Xuheng Ding, Isak Stomberg, Simon Birrer, Tomas Snyder, Matthew A. Malkan, Andrew W. Stephens, Matthew W. Auger

Physics

The tight correlations between the mass of supermassive black holes (M_BH) and their host-galaxy properties have been of great interest to the astrophysical community, but a clear understanding of their origin and fundamental drivers still eludes us. The local relations for active galaxies are interesting in their own right and form the foundation for any evolutionary study over cosmic time. We present Hubble Space Telescope optical imaging of a sample of 66 local active galactic nuclei (AGNs); for 14 objects, we also obtained Gemini near-infrared images. We use state-of-the-art methods to perform surface photometry of the AGN host …

Scenarios For Offshore Wind Power Production For Central California Call Areas, Yi-Hui Wang, Ryan K. Walter, Crow White, Matthew D. Kehrli, Benjamin Ruttenberg

Physics

In response to the growing interest in offshore wind energy development in California, the U.S. Bureau of Ocean Energy Management delineated three Call Areas for potential leasing. This study provides a comprehensive characterization and comparison of offshore wind power potential within the two Central California Call Areas (Diablo Canyon and Morro Bay) using 12-and 15-MW turbines under different inter-turbine spacing and wind farm size scenarios. Our analysis shows similar daily and seasonal patterns of wind power produced within the Call Areas, which peak in spring and during evening hours. Per-turbine power production is higher in the Morro Bay Call Area …

Potential Environmental Effects Of Deepwater Floating Offshore Wind Energy Facilities, Hayley Farr, Benjamin Ruttenberg, Ryan K. Walter, Yi-Hui Wang, Crow White

Physics

Over the last few decades, the offshore wind energy industry has expanded its scope from turbines mounted on foundations driven into the seafloor and standing in less than 60 m of water, to floating turbines moored in 120 m of water, to prospecting the development of floating turbines moored in ~1,000 m of water. Since there are few prototype turbines and mooring systems of these deepwater, floating offshore wind energy facilities (OWFs) currently deployed, their effects on the marine environment are speculative. Using the available scientific literature concerning appropriate analogs, including fixed-bottom OWFs, land-based wind energy facilities, wave and tidal …

Assessing Stream-Aquifer Connectivity In A Coastal California Watershed, Bwalya Malama, Devin Pritchard-Peterson, John J. Jasbinsek, Christopher Surfleet

Physics

We report the results of field and laboratory investigations of stream-aquifer interactions in a watershed along the California coast to assess the impact of groundwater pumping for irrigation on stream flows. The methods used include subsurface sediment sampling using direct-push drilling, laboratory permeability and particle size analyses of sediment, piezometer installation and instrumentation, stream discharge and stage monitoring, pumping tests for aquifer characterization, resistivity surveys, and long-term passive monitoring of stream stage and groundwater levels. Spectral analysis of long-term water level data was used to assess correlation between stream and groundwater level time series data. The investigations revealed the presence …

Space Telescope And Optical Reverberation Mapping Project. Ix. Velocity–Delay Maps For Broad Emission Lines In Ngc 5548, Keith Horne, G. De Rosa, B. M. Peterson, A. J. Barth, Vardha N. Bennert, Y. Zu

Physics

In this contribution, we achieve the primary goal of the active galactic nucleus (AGN) STORM campaign by recovering velocity–delay maps for the prominent broad emission lines (Lyα, C IV, He II, and Hβ) in the spectrum of NGC 5548. These are the most detailed velocity–delay maps ever obtained for an AGN, providing unprecedented information on the geometry, ionization structure, and kinematics of the broad-line region. Virial envelopes enclosing the emission-line responses show that the reverberating gas is bound to the black hole. A stratified ionization structure is evident. The He II response inside 5–10 lt-day has a broad single-peaked velocity …

Effects Of Estuary-Wide Seagrass Loss On Fish Populations, Jennifer K. O'Leary, Maurice C. Goodman, Ryan K. Walter, Kariss Willits, Daniel J. Pondella

Physics

Globally, habitat loss in coastal marine systems is a major driver of species decline, and estuaries are particularly susceptible to loss. Along the United States Pacific coast, monospecific eelgrass (Zostera marina) beds form the major estuarine vegetated habitat. In Morro Bay, California, eelgrass experienced an unprecedented decline of > 95%, from 139 ha in 2007 to < 6 ha by 2017. Fish populations were compared before and after the eelgrass decline using trawl surveys. Beach seines surveys were also conducted during the post-decline period to characterize species within and outside of remnant eelgrass beds.While the estuary-wide loss of eelgrass did not result in fewer fish or less biomass, it led to changes in species composition. The post-eelgrass decline period was characterized by increases in flatfish (mainly Citharichthys stigmaeus) and staghorn sculpin (Leptocottus armatus), and decreases in habitat specialists including bay pipefish (Syngnathus leptorhynchus) and shiner perch (Cymatogaster aggregata). There were similar trends inside and outside of remnant eelgrass patches. These findings support evidence across multiple ecosystems suggesting that the predominance of habitat-specialists predicts whether or not habitat loss leads to an overall decline in fish abundance. In addition, loss of critical habitats across seascapes can restrict population connectivity and lead to range contraction. For bay pipefish, the loss of eelgrass in Morro Bay is likely to create a population biogeographic divide. Currently, Morro Bay is dominated by flatfish and sculpins, and the longevity of this new ecosystem state will depend on future eelgrass recovery dynamics supported by ecosystem-based management approaches.

Machine Learning Based Predictions Of Dissolved Oxygen In A Small Coastal Embayment, Manuel Valera, Ryan K. Walter, Barbara A. Bailey, Jose E. Castillo

Physics

Coastal dissolved oxygen (DO) concentrations have a profound impact on nearshore ecosystems and, in recent years, there has been an increased prevalance of low DO hypoxic events that negatively impact nearshore organisms. Even with advanced numerical models, accurate prediction of coastal DO variability is challenging and computationally expensive. Here, we apply machine learning techniques in order to reconstruct and predict nearshore DO concentrations in a small coastal embayment while using a comprehensive set of nearshore and offshore measurements and easily measured input (training) parameters. We show that both random forest regression (RFR) and support vector regression (SVR) models accurately reproduce …

A Significant Excess In Major Merger Rate For Agns With The Highest Eddington Ratios At Z < 0.2, Victor Marian, Knud Jahnke, Irham Andika, Eduardo Bañados, Vardha N. Bennert, Seth Cohen, Bernd Husemann, Melanie Kaasinen, Anton M. Koekemoer, Mira Mechtley, Masafusa Onoue, Jan-Torge Schindler, Malte Schramm, Andreas Schulze, John D. Silverman, Irina Smirnova-Pinchukova, Arjen Van Der Wel, Carolin Villforth, Rogier A. Windhorst

Physics

Observational studies are increasingly finding evidence against major mergers being the dominant mechanism responsible for triggering an active galactic nucleus (AGN). After studying the connection between major mergers and AGNs with the highest Eddington ratios at z = 2, we here expand our analysis to z < 0.2, exploring the same AGN parameter space. Using ESO VLT/FORS2 B-, V-, and color images, we examine the morphologies of 17 galaxies hosting AGNs with Eddington ratios , and 25 mass- and redshift-matched control galaxies. To match the appearance of the two samples, we add synthetic point sources to the inactive comparison galaxies. The combined sample of AGN and inactive galaxies was …

Space Telescope And Optical Reverberation Mapping Project. Xii. Broad-Line Region Modeling Of Ngc 5548, P. R. Williams, A. Pancoast, T. Treu, B.J. Brewer, Vardha N. Bennert, Y. Zu

Physics

We present geometric and dynamical modeling of the broad line region (BLR) for the multi-wavelength reverberation mapping campaign focused on NGC 5548 in 2014. The data set includes photometric and spectroscopic monitoring in the optical and ultraviolet, covering the Hβ, C iv, and Lyα broad emission lines. We find an extended disk-like Hβ BLR with a mixture of near-circular and outflowing gas trajectories, while the C iv and Lyα BLRs are much less extended and resemble shell-like structures. There is clear radial structure in the BLR, with C iv and Lyα emission arising at …

Large-Scale Erosion Driven By Intertidal Eelgrass Loss In An Estuarine Environment, Ryan K. Walter, Jennifer K. O'Leary, Sean Vitousek, Mohsen Taherkhani, Carolyn Geraghty, Ann Kitajima

Physics

Seagrasses influence local hydrodynamics by inducing drag on the flow and dampening near-bed velocities and wave energy. When seagrasses are lost, near-bed currents and wave energy can increase, which enhances bottom shear stresses, destabilizes sediment, and promotes suspension and erosion. Though seagrasses are being lost rapidly globally, the magnitude of change in sediment stabilization following ecosystem-wide eelgrass loss has rarely been measured. In this study, we explored the geomorphological changes associated with an unprecedented estuary-wide collapse of a seagrass (eelgrass, Zostera marina) in Morro Bay, CA, USA. Morro Bay has historically suffered from accelerated sedimentation and accretion. However, following …

Abalone Recruitment In Abalone Recruitment In Low-Density And Aggregated Populations Facing Climatic Stress, Ryan K. Walter

Physics

Understanding spatial and temporal patterns in the recruitment of marine invertebrates with complex life histories remains a critical knowledge gap in marine ecology and fisheries. As marine invertebrates are facing multiple stressors from overfishing and climatic stress, it is important to evaluate the conditions that facilitate recruitment in low-density populations. The red abalone Haliolis rufescens historically supported an economically important fishery in California, but the fishery was sequentially closed as stocks declined, and the last fished area was closed in 2018 following the collapse of the kelp forests in Northern California. Here, red abalone recruitment was evaluated annually from 2012 …

Modeling The Evolution Of Differences In Variability Between Sexes, Theodore P. Hill

Research Scholars in Residence

An elementary mathematical theory based on a “selectivity-variability” principle is proposed to address a question raised by Charles Darwin, namely, how one sex of a sexually dimorphic species might tend to evolve with greater variability than the other sex. Two mathematical models of the principle are presented: a discrete-time one-step probabilistic model of the short-term behavior of the subpopulations of a given sex, with an example using normally distributed perceived fitness values; and a continuous-time deterministic coupled ODE model for the long-term asymptotic behavior of the expected sizes of the subpopulations, with an example using exponentially distributed fitness levels.