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Full-Text Articles in Physics

Memory Capacity In A System Of Swelling Particles, David T. Keating Mar 2022

Memory Capacity In A System Of Swelling Particles, David T. Keating

Physics

A system has the ability to store memory if one is able to write, retrieve, and erase information from it. Some systems are capable of storing multiple transient memories; with no noise in these systems, at long time, the memories degrade until one or two remain. The addition of noise to these systems can extend the retention of multiple memories, in some cases indefinitely [2, 3]. While this behavior was first observed in simulations of charge density waves, it has since appeared in other systems [1].

Past research has shown that sheared non-Brownian liquid suspensions of particles exhibit similar behavior …


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 Jan 2022

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 Jan 2022

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 …


Swarming Oscillators With Time-Delayed Interactions, Nicholas S. Blum Dec 2021

Swarming Oscillators With Time-Delayed Interactions, Nicholas S. Blum

Physics

We investigate the role of delay in the collective dynamics of particles that swarm in space and possess an internal oscillatory degree of freedom, called swarmalators. Swarmalators were introduced recently by O’Keeffe, Hong, and Strogatz in Nature Communications 8, 1504 (2017). The addition of a time delay into the system of swarmalators was motivated by the biology of early embryonic development. This delay leads to a rich phenomenology, which includes two new collective states, which we call "semi-static crystal" and "boiling". In the semi-static crystal state, all particles in a cluster undergo decaying radial oscillations completely in phase with one …


Rigid Aggregation Of Inclusions Embedded In Quasi 2d Fluids, Natalie Xochitl Ryan Dec 2021

Rigid Aggregation Of Inclusions Embedded In Quasi 2d Fluids, Natalie Xochitl Ryan

Physics

Diffusion is a transport process common in several biological systems. In this process particles of different species mix together through random (stochastic) motion at molecular length scales. Diffusion in fluids is unique as the coupling of the flow and fluid have been found to produce giant concentration fluctuations. The molecular length scale of these concentration fluctuations are magnitudes larger than the movement of the particles themselves, earning them the title “giant”. The diffusion of particles in bio-membranes displays a combination of 2D and 3D hydrodynamic properties; the movements of the particles are restricted to the plane of the membrane and …


Plasma-Laser Wakefield Acceleration, Jonathan Babu Dec 2021

Plasma-Laser Wakefield Acceleration, Jonathan Babu

Physics

Many texts detailing the derivations and science of Wakefield Acceleration are aimed at graduate and doctorate level scholars, and these may seem intimidating to new physics students. This paper is meant to be an introduction to the nature of plasmas, lasers, laser-plasma interactions, and Laser Wakefield Acceleration (LWFA), with sources given where extra detail may be required. I recognize that this paper is not meant to be an all-encompassing review on the nature of the topics, as these topics are complex and subject of entire textbooks. Instead, I aim to provide an introduction to these topics to a college-level scholar …


Lorentz Violations And The Casimir Effect, Samuel G. Christensen Dec 2021

Lorentz Violations And The Casimir Effect, Samuel G. Christensen

Physics

The background and calculation for the corrections to the Casimir Energy stored on parallel conducting plates due to minimal violations of Lorentz invariance are presented as a test of the Standard Model. A direction-dependent photon dispersion relation using operators of dimension 4 and higher is used in the calculation of the spacetime anisotropy correction terms to the Casimir energy. The calculation includes discussion of Riemann zeta function regularization and its equivalence to Euler-Maclaurin sum-integral formulas in a Casimir effect calculation. The two plate geometry result is mapped onto a one plate and sphere geometry to cater to modern precision tests …


Modeling Cherenkov Light Detection Timing For The Very Energetic Radiation Imaging Telescope Array System, Keilan Finn Ramirez Dec 2021

Modeling Cherenkov Light Detection Timing For The Very Energetic Radiation Imaging Telescope Array System, Keilan Finn Ramirez

Physics

The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is an array of four 12-meter telescopes which use the Imaging Atmospheric Cherenkov Technique to conduct high-energy gamma-ray astronomy. VERITAS detects magnitude and location information associated with Cherenkov light, and uses this information to indirectly observe gamma-rays through a software reconstruction process. VERITAS also records timing information corresponding to Cherenkov light detection, and this additional information could theoretically be incorporated into the reconstruction process to improve the accuracy of gamma-ray observations. The first step to including timing information is to understand when Cherenkov light detection would be expected from a known …


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 Nov 2021

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 Oct 2021

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 (MBH) 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 …


Rapid Warming Events In A Small Coastal Upwelling Embayment, Tatjana E. Ellis Jun 2021

Rapid Warming Events In A Small Coastal Upwelling Embayment, Tatjana E. Ellis

Physics

Temperature variability in the nearshore coastal ocean influences various biological processes and can drive changes in biodiversity and habitat range. Despite recent progress, there are still significant gaps in the understanding of drivers of temperature variability in upwelling bays, particularly at higher frequencies. In this study, we analyzed a decade of nearshore temperature measurements both inside and outside a small coastal embayment located in central California [San Luis Obispo (SLO) bay], as well as temperature data from satellites, to characterize rapid warming events. We found that rapid warming events, defined using rates of temperature change across different thresholds, occurred more …


Direct Drive Solar Panel Control Circuit, Marcorios Bekheit May 2021

Direct Drive Solar Panel Control Circuit, Marcorios Bekheit

Physics

A control circuit is built for insulated solar electric cookers (ISEC). Power delivery and temperature safety are the focus. Using a maximum power point tracking (MPPT) algorithm, Arduino Nano, voltage and current sensors, and a buck converter, the solar panel’s output power was maximized for a direct load heat resistor with 3.5Ω for a range of solar intensities. Using a resistance temperature detector, a temperature sensor is built for safety shutoff.


Scenarios For Offshore Wind Power Production For Central California Call Areas, Yi-Hui Wang, Ryan K. Walter, Crow White, Matthew D. Kehrli, Benjamin Ruttenberg May 2021

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 …


Quantum Computing: Resolving Myths, From Physics To Metaphysics, Jacob R. Mandel Mar 2021

Quantum Computing: Resolving Myths, From Physics To Metaphysics, Jacob R. Mandel

Physics

As the field of quantum computing becomes popularized, myths or misconceptions will inevitably come along with it. From the sci-fi genre to the casual usage of the term quantum, idealism begins to take over our projections of the technological future. But what are quantum computers? And what does quantum mean? How are they any different than the computers we use on an everyday basis? Will there be quantum computing smartphones? Are quantum computers just a faster version of conventional computing or a wholly new way of computing altogether? The objective of this paper is to resolve common myths or misconceptions …


Lorentz Violation In Neutrino Interactions, Pranav Jayaram Seetharaman Mar 2021

Lorentz Violation In Neutrino Interactions, Pranav Jayaram Seetharaman

Physics

Both the Standard Model of particle physics and General Relativity require Lorentz symmetry as a fundamental building block. In this paper, we learn about a framework called the Standard Model Extension that allows us to determine how physical phenomenon would change if we deviated from Lorentz invariance in the Standard Model and General Relativity. We use the Standard Model Extension to analyze a specific high-energy, astrophysical neutrino interaction that is only possible if Lorentz symmetry can be broken. The interaction we look at is the decay of a neutrino into an electron-positron pair, which is not possible in conventional physics. …


Potential Environmental Effects Of Deepwater Floating Offshore Wind Energy Facilities, Hayley Farr, Benjamin Ruttenberg, Ryan K. Walter, Yi-Hui Wang, Crow White Mar 2021

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 …


Ultrafast Investigation And Control Of Dirac And Weyl Semimetals, Christopher P. Weber Feb 2021

Ultrafast Investigation And Control Of Dirac And Weyl Semimetals, Christopher P. Weber

Physics

Ultrafast experiments using sub-picosecond pulses of light are poised to play an important role in the study and use of topological materials and, particularly, of the three-dimensional Dirac and Weyl semimetals. Many of these materials’ characteristic properties—their linear band dispersion, Berry curvature, near-vanishing density of states at the Fermi energy, and sensitivity to crystalline and time-reversal symmetries—are closely related to their sub- and few-picosecond response to light. Ultrafast measurements offer the opportunity to explore excitonic instabilities and transient photocurrents, the latter depending on the Berry curvature and possibly quantized by fundamental constants. Optical pulses may, through Floquet effects, controllably and …


Assessing Stream-Aquifer Connectivity In A Coastal California Watershed, Bwalya Malama, Devin Pritchard-Peterson, John J. Jasbinsek, Christopher Surfleet Feb 2021

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 Feb 2021

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 …


The Structure Function Relationship Of Disordered Networks Using Young's Modulus And Floppy Modes, Melinda Grace Tajnai Feb 2021

The Structure Function Relationship Of Disordered Networks Using Young's Modulus And Floppy Modes, Melinda Grace Tajnai

Physics

Disordered networks may have the ability to store information that can be retrieved using a Young’s modulus measurement. The effect of the number of floppy modes a network has on the value of this Young’s modulus measurement is unknown. This experiment uses 28 networks consisting of 3D printed edges in a sliding frame to determine how the Young’s modulus of a network is related to the number of floppy modes.


Effects Of Estuary-Wide Seagrass Loss On Fish Populations, Jennifer K. O'Leary, Maurice C. Goodman, Ryan K. Walter, Kariss Willits, Daniel J. Pondella Jan 2021

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 Dec 2020

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 Nov 2020

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 …


Using Current-Voltage Characteristics To Probe The Transport Mechanism In Carbon Nanotube Networks, Alejandro Jimenez Nov 2020

Using Current-Voltage Characteristics To Probe The Transport Mechanism In Carbon Nanotube Networks, Alejandro Jimenez

Physics

Carbon nanotube (CNT) random networks have shown great promise in electronic applications. For example, they have been used as the active layer in thin film transistor biosensors and as electrodes in supercapacitors (Hu, 2010). Although CNT networks applications are numerous, some of the key details of their electrical behavior are not fully understood. In particular, it is known that the junctions between tubes in CNT networks play a key role in determining the sensing properties of the network (Thanihaichelvana, et al., 2018), however, the mechanism by which metallic-semiconducting (m-s) tube junctions affect the electrical sensing properties of the network is …


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 Oct 2020

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 Sep 2020

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 …


Variability Of Active Galactic Nuclei From Differential Photometry, Nicholas Steven Yee Sep 2020

Variability Of Active Galactic Nuclei From Differential Photometry, Nicholas Steven Yee

Physics

The Seoul AGN Monitoring Project, or SAMP for short, is an international project (PI Jonghak Woo from Korea) with the goal of measuring the masses of black holes residing in the center of massive active galactic nuclei (AGNs). AGNs are some of the brightest objects in the universe. Their light is attributed to the accretion of material onto the black hole. However, these objects are too distant to spatially resolve the gravitational sphere of influence of the black hole directly. Instead, we use a technique called reverberation mapping which observes the variability of the AGN power-law continuum emission and the …


Abalone Recruitment In Abalone Recruitment In Low-Density And Aggregated Populations Facing Climatic Stress, Ryan K. Walter Aug 2020

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 …


Cooking Systems Using Aluminum Foam, Ryan Tetsuo Mizukami Aug 2020

Cooking Systems Using Aluminum Foam, Ryan Tetsuo Mizukami

Physics

In developing countries, the use of wood burning fires for cooking is cause for illness and death. With this in mind, research was conducted to develop a solar cooking device capable of cooking of soup within 15 mins in order to reduce the negative impacts of cooking with wood. Current methods of solar-based cooking, such as solar concentrators and solar tube ovens, are impractical. A small solar panel is a cost-effective way to produce energy but will not produce enough power to cook within a reasonable amount of time. Even if it is assumed that all of the energy produced …


Learning Assistant And Instructor Communication: Impacts On Perceived Efficacy, Jahangir Rassouli, Laura Ríos Jul 2020

Learning Assistant And Instructor Communication: Impacts On Perceived Efficacy, Jahangir Rassouli, Laura Ríos

Physics

The Learning Assistant (LA) Model was co-developed by Richard McCray and Valerie Otero at the University of Colorado Boulder in 2003. In this model, senior undergraduate students serve as facilitators for group discussion in lower-division courses, and employ evidenced-based practices for promoting inquiry and active learning [1]. Since its inception, the LA model has grown to various departments, disciplines, and universities.

At California Polytechnic State University San Luis Obispo (Cal Poly), the LA program in the physics department is still in its early stages. As such, it is an environment rich for exploration into the affordances, limitations, and benefits of …