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Defending the Freedom to Read: Policies, Procedures & Civic Engagement
Get PDFAuthor of On Censorship: A Public Librarian Examines Cancel Culture in the US (Fulcrum, 2023), LaRue has dealt with over 1,200 challenges in his career as a public library director and former Executive Director of ALA’s Office for Intellectual Freedom. This talk will focus on the four reasons library resources are challenged, what tactics are used to impose censorship today, and why public engagement is essential to challenge resolution.N
The Creation of the Tribal Nations of Oklahoma Metadata Database
Get PDFIn the closing discussions of last year's symposium the impromptu creation of the Metadata Justice Collective occurred. Those that volunteered to chair, Megan Macken, Lulu Zilinskas, and Kaitlyn Palone, met shortly thereafter about possible projects that could use collaborative work. Megan presented the idea to create a database of Oklahoma Tribal Nation preferred names. The speakers presented on how this work was accomplished, problems encountered, and plans for future
Disentangling the Formation Pathways of Protostars
Get PDFStar formation occurs within dense cores within molecular clouds, often associated with filamentary structures. However, there exist isolated instances of star formation, far from nearby forming stars. As a core collapses, a rotationally supported circumstellar disk emerges around a central, gravitating potential with the accretion of gas and dust playing a vital role in regulating the subsequent stellar mass assembly. With recent studies revealing nearly half of all solar-type star systems are multiples, this raises questions about the mechanisms behind their formation. Furthermore, despite numerous discoveries of exoplanets with state-of-the-art space telescopes, the initial stages of planetary formation remain elusive. High-resolution interferometric imaging using ALMA of protoplanetary disks has ubiquitously unveiled intricate substructures, hinting at ongoing planet formation processes. To understand the formation and evolution of stars and their planetary systems, it is essential to better characterize their progenitors, known as "protostars”, particularly the youngest known phases of protostars, so-called Class 0. During the early stages of star formation, when gravitational collapse initiates, the conservation of angular momentum leads to the formation of a rotationally supported disk. However, only a handful of Class 0 protostellar disks, which are highly embedded in gas and dust, have been rigorously detailed so far. Consequently, a more comprehensive analysis of Class 0/I systems is imperative for understanding their formation and evolution. This dissertation aims to address multiple outstanding questions in star formation, beginning with a detailed investigation of an extraordinary triple-source protostellar Class 0 system, L1448 IRS3B. Expanding the focus, BHR7, an isolated Class 0 source, is studied to map the transfer of angular momentum from 1000s of au down to the disk. BHR7 serves as an ideal testbed for non-ideal MHD theory and represents a prototypical isolated Class 0 source, free from contamination by nearby forming stars. Furthermore, a high-resolution survey is conducted in the Perseus region, encompassing 12 known multiple star systems, to determine the most probable formation pathways for each of these sources. Rigorous modeling techniques and statistical tests are employed to disentangle the formation pathways of the protostars. By undertaking these investigations, I aim to enhance our understanding of star formation processes, provide observational constraints on star formation theory, and shed light on the complex formation mechanisms underlying multiple star systems, which are thought to be the early stages of exoplanet progenitors
Gridded Hail Nowcasting using UNets, Lightning Observations, and the Warn-on-Forecast System
Get PDFHailstorms cause around 1 billion dollars in damage across the United States each year. At least a portion of this cost is associated with the inability to protect personal assets from damage in the short window of time offered by a severe weather warning. To address this problem, we developed a nowcasting model that uses UNet style convolutional neural networks (CNNs) to produce gridded severe hail forecasts for the next hour. One of the advantages of machine learning models is their ability to fuse large quantities of data from traditionally disparate sources such as ground observations and model output to produce a forecast. To exploit this hybrid predictor potential, these models are trained on the high-resolution (3 km spatial, 5 min temporal) output from the Warn-on-Forecast System (WoFS) numerical weather prediction (NWP) ensemble and remote sensing observations from Vaisala’s NLDN lightning detection system. Maximum expected size of hail (MESH) from the gridded NEXRAD WSR-88D radar (GridRad) dataset is used as the model’s truth labels. In addition to traditional machine learning optimization techniques such as hyperparameter searches and predictive feature selection, several different UNet architectures are compared to obtain a better machine learning model. The high-resolution nature of this data enables strategies such as using time as an additional dimension in a 3D UNet. This 3D model is compared against the effectiveness of a traditional 2D UNet. Finally, both models are compared against HAILCAST and simple logistic regression trained on 2 to 5 km updraft helicity to investigate their effectiveness
Evolution and Stability of Ultra-Wide Trans-Neptunian Binaries
Get PDFThis research is focused around the longevity and formation of a class of binaries in the Kuiper Belt called Ultra-Wide Trans-Neptunian Binaries (Ultra-Wide TNBs). The presence of these seemingly fragile binary systems has been used to constrain various properties in both the modern Kuiper Belt and its primordial origins. By studying the evolution and potential formation of these binaries, even more can be learned and some things can be reassessed.
Using the SWIFT Regularized Mixed Variable Symplectic (RMVS) n-body integrator, we simulate the evolution of a number of binary systems perturbed by both collisions and gravitational perturbations. We show that Ultra-Wide TNBs like 2001 QW322 and 2000 CF105, which had previously been seen as stable, are unlikely to have formed in the primordial Kuiper Belt and remain intact into the modern day. We also show that these same binaries can be formed by the gradual widening of initially tighter binaries under the same perturbations. These widened binaries bear properties consistent with observations and are produced efficiently enough to explain their present day population size.
If some Ultra-Wide TNBs are not primordial, then metrics using their survival to constrain the Size Frequency Distribution (SFD) of the Kuiper Belt are not effective. If Ultra-Wide TNBs are primarily formed through widening, their population size can be used to constrain this SFD, and the mass of the initial Kuiper Belt. In addition, the presence and formation of blue Ultra-Wide TNBs in the Cold Classical Belt can indicate the nature of Neptune's migration in the early Solar System
Defining a Relatively Normal Tornado Day: An Exploration of the Climatology and Potential Use of Relative Risk Forecasts for Tornadoes
Get PDFThe risks posed by rare and severe weather events are both the most impactful to the public and the most difficult to communicate, due to their low absolute probability of occurrence but high impact at a given point. Recent research on rare risk communication has found that probabilistic information is the most effective way to communicate the risk posed by weather to members of the public, but also that small absolute probabilities can be misinterpreted due to known cognitive biases. One potential solution to communicating rare event likelihoods is a value called relative risk, which this work holistically investigates in the context of tornado risk communication. Relative risk is defined as the ratio of the forecast likelihood of an event to the background likelihood of that event occurring, the quotient of which describes how many times more likely than “normal” an event is for a given forecast. To achieve a broader understanding of how relative risk for tornadoes might impact different aspects of tornado risk communication, a 1950-2021 climatology of tornado relative risks was studied alongside focus group and survey data collection that investigated the reception of relative risk information by broadcast meteorologists and members of the public.
First, the 1950-2021 US observed tornado dataset maintained by the Storm Prediction Center (SPC) was used to calculate relative risks for tornadoes for all events across the 71 year period. Observed tornado reports were used to calculate the climatological likelihood of a tornado within 25 miles of a point for every day of the year, as well as Practically Perfect Hindcasts (PPHs) for tornadoes for every day in the 71-year dataset. Dividing these PPHs by the daily 1950-2021 tornado climatology produced a full series of relative risk values. Analysis of the 71 years of relative risk data revealed that the highest values of relative risk occur across the western and northern regions of the contiguous US where tornadoes can be rare, while the lowest values of relative risk were observed in the southern US where tornadoes occur year-round. Relative risks values of 5, 20, 50, 100, 250, and 700 times more likely than normal were observed to occur across the 71-year dataset at similar rates to the absolute likelihood values of 2, 5, 10, 15, 30, and 45% used in the SPC probabilistic outlook, and were thus chosen to be used in in mapped presentations of relative risk to potential users. Overall, these results suggest that relative risks likely have the greatest value for communicating tornado events that occur in areas with established tornado climatology when tornadoes occur during off-season times of year or in places that they are more infrequent.
Next, focus group interviews with broadcasters revealed a great deal of suspicion of towards viewers’ ability to interpret probability information in any form. Broadcasters in these interviews believed that relative risk information might be seen as overblown, potentially inducing unnecessary panic in their viewers. Relative risk was seen by broadcasters as a useful tool for their personal use in quantifying how unusual a tornado event was, and a few suggested they would present relative risk during tornado for events occurring outside of tornado season or outside of tornado-prone regions.
Finally, members of the public were also surveyed about their perceived level of concern and likelihood of response when shown different levels of relative risk information. Participants on average reported large increases in concern when shown only relative risk information but presenting both absolute and relative risk information led to better differentiation in level of concern across increasing absolute likelihood risk levels. Later experiments added nuance to these findings, and showed that although relative risk information at values as high as 500 times more likely than normal had no effect on participant trust in future forecasts if that forecast were a false alarm, there was also no change to participant concern or likelihood of response across increasing levels of relative risk with a constant absolute risk value.
Through a series of three investigations, this dissertation attempts to develop and test a potential forecast product in a rigorous and methodical way that combines key understandings from both the meteorological and social sciences. Following this process helps ensure that both the potential range of values the product may contain and the range of responses that product recipients will display are well-understood. These rigorous efforts have revealed that although relative risk information could be valuable in specific situations for communicators like broadcast meteorologists, it does not appear to have significant effects on individual risk assessment or decision-making for members of the public. Thus, relative risk does not appear to offer a silver bullet for improving the communication of rare events like tornadoes
What is guiding the health information-seeking behaviors of right-leaning Christians regarding the COVID-19 vaccines?
Get PDFResearch has shown that politics influence Americans’ religious identities (Christian, atheist, etc.) and behaviors (church attendance). However, the research on how right-leaning Christians view the Covid-19 vaccines (and other measures to control the virus) has focused mainly on religion as driving the narrative (through Christian nationalism, etc.). Research also has not been done on where right-leaning Christians are receiving (and not receiving) information on the Covid-19 vaccines. This study aims to fill this gap by analyzing 17 interviews with right-leaning Christians about their information-seeking behavior on the Covid-19 vaccines. Contrary to media reports about famous pastors discussing the Covid-19 vaccines, the participants seldom discussed them in their churches. Also, most of my participants’ information-seeking behavior was driven by politics and their preconceived notions about vaccines rather than religion. The messages they received about the vaccines from these sources had a secular and political bent, not a religious one. This study adds to the research on Covid-19 and religion by suggesting that many right-leaning Christians' negative feelings toward the vaccines were driven more by politics than religion
Collective Behaviors of Quantum Emitters Coupled to a Structured Photonic Environment
Get PDFThe study of a quantum system coupled to an environment plays an indispensable role in expanding our understanding of quantum mechanics. It has a broad impact, encompassing fundamental inquiries in quantum physics as well as applications in quantum technologies. The primary focus of our work is on a ''big'' quantum system that consists of two distinct subsystems, one characterized by spin degrees of freedom and the other by bosonic degrees of freedom. Our research falls in the realm of quantum optics, where the bosonic degrees of freedom which constitute the ''environment'' are realized by photons in cavities. The spin degrees of freedom are realized by two-level quantum emitters that represent the ''system'' under study. The collective radiative behaviors of the emitters coupled to a single mode cavity are described frequently by the Dicke model, which treats a subset of the full Hilbert space. Motivated by recent experimental developments in quantum optics and circuit quantum electrodynamics (QED) platforms, we replaced the single-mode cavity by a one-dimensional array of coupled cavities with Kerr-like non-linearity. The presence of the Kerr-like non-linearity gives rise to a nontrivial mode structure of the bath that supports two-photon bound states. Working in the weak emitter-photon coupling regime, we investigated collective behaviors exhibited by a group of quantum emitters in the two-excitation manifold. We developed a theoretical atom-optical framework that treats the emitter-photon coupled system fully quantum mechanically. We covered a wide range of theoretical approaches in our study, starting from the Schroedinger equation and extending to the Markov approximation, which is critical also for quantum master equation treatment. By using the theoretical atom-optical framework, we sought to identify the radiative pathways and effective interactions of the emitters coupled to the structured photonic environment. For two excited emitters with transition energy in resonance with the two-photon bound state band, the radiative properties were studied. It was found that when the emitters are in resonance with the band edge and are well-separated, undamped Rabi oscillations occur; Rabi oscillations do not exist without the Kerr-like nonlinearity. A photonic polaron-like state that forms as a result of all-to-all interaction in the center-of-mass momentum space of the two-photon bound states was identified. For an emitter array with a large number of emitters, operating within the band gap regime, an effective spin Hamiltonian was derived. Interestingly, a reversal in the hierarchy of interaction energy scales was observed. This led to the discovery of a series of novel correlated bound states that exhibit droplet-like characteristics. The findings of our atom-optical theory provide a guide for future experimental and theoretical studies of spin-boson coupled systems. The parameter regimes considered in this thesis can be applied to several circuit QED experimental platforms and the predictions can be tested with state-of-the-art technology
Comparing ambient-noise-based seismic velocity variations with dynamic and static strain changes associated with major earthquake rupture at Parkfield
Get PDFStress perturbations across a fault zone can change seismic wave velocity in the adjacent area, with implications for rock properties and fault mechanics. Ambient noise seismic interferometry is increasingly used to retrieve information about wave propagation between seismic stations, constrain seismic velocity changes, and potentially monitor the subsurface strain field. Comparing seismic velocity changes with strain changes in space and time may help us understand the damage and healing processes of fault rocks. Here we study the seismic velocity and strain changes in the shallow crust associated with the 2004 Mw 6.0 Parkfield earthquake in California. We process continuous seismic recordings from 13 stations of the High Resolution Seismic Network (HRSN) from 2001 to 2007. Then we use an open-source software NoisePy (Jiang and Denolle, 2020) to cut band-pass-filtered data into 1-hour chunks and perform cross-correlation, stack hourly cross-correlation functions into 30-day averages, and retrieve reference Green’s functions based on a criteria of cross-correlation coefficients. To estimate the history of relative velocity changes, dv/v, we use a moving-window cross spectrum method with a moving window of 30 days. To resolve potential spatial variations in velocity changes, we first fit the dv/v history with a parametric function with seasonal, offset, and logarithmic terms, then select better-fitting station pairs based on signal-to-residual ratios and map the coseismic velocity changes at 5 frequency bands. We also assess the relationship between dv/v estimates, peak dynamic strains from strong-motion seismograms, and static strain changes inferred from coseismic and postseismic space-geodetic measurements. Our results show larger amplitudes of coseismic velocity drops in higher frequency bands for both network-averaged and station-pair dv/v values. We attribute the instantaneous drop of dv/v to ground shaking during the earthquake and the later gradual increase of dv/v to the postseismic recovery of shallow fault zones. While the coseismic dv/v changes suggest potential spatial variations across the fault, future efforts are needed to quantify and reduce uncertainties. Our study will help improve strategies to obtain robust dv/v time series and distinguish the causes of seismic velocity changes in the subsurface