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A Study on the Propagation and Exploitation of Structured Light in Underwater Turbulence
Get PDFThe development and optimization of optical systems will play a pivotal role in the continued exploration and exploitation of the world’s underwater environments. These systems offer advantages in many sectors, and includes applications in areas such as high-speed communication, advanced sensing and imaging, and environmental characterization and monitoring. Underwater environments offer a plethora of challenges, however, and mitigating these obstacles remains an arduous task. In this work, the inherent advantages of structured light are leveraged to optimize optical system performance through non-ideal underwater conditions. Additionally, fundamental relationships between the generation of specified structured modes and their interactions with complex environments are studied, and pertinent environmental information is presented.
An underwater turbulence emulator (UTE) is created to generate stable, repeatable, and reasonable turbulent underwater conditions. The UTE serves as a testbed for all optical propagation experiments described in this work, allowing for the detailed analysis of the interaction between generated structured modes and a dynamic underwater environment. The conditions within the UTE are characterized using optical and thermal methods.
Using a modified Higher Order Bessel Beams Integrated in Time (HOBBIT) system, reliant on an acousto-optic deflector (AOD) and coordinate transform log-polar optics, a probe and control system is demonstrated to exploit optical channels within a turbulent underwater environment. The exploitation of the channels increases system performance in both received optical power and the ability to support a high-speed optical communication link. Further, the system successfully exploits channels in a turbid and turbulent environment. The ability to exploit multiple channels simultaneously is demonstrated, providing relevant information about the density and distribution of the channels within the turbulent environment.
In an effort to experimentally realize unperturbed propagation through a turbulent volume, non-diffracting beams are rapidly generated and manipulated using the HOBBIT generation architecture. Experimental generation of arbitrary non-diffracting modes is shown through the alteration of the angular spectrum around a perfect vortex envelope. Leveraging this rapid and customizable generation method, a circular volume of underwater turbulence is probed with off-axis Bessel-Gauss (BG) beams. Due to the speed of the probing system, instantaneous realizations of the turbulence are scanned, and optimal propagation paths are determined in which the input beam closely matches the output beam, indicating relatively unperturbed transmission through the turbulent volume. It is demonstrated that the beams within these optimal channels are less affected by the turbulence than beams outside of these paths, including reduced levels of beam wander and scintillation comparatively. Within the probed volume of underwater turbulence, the prevalence and persistence of these channels is determined, proving key insights for further exploitation of the environment. The propensity for simultaneous propagation through multiple unperturbed channels is verified through the application of superposition.
Utilizing a non-diffracting beam basis, a rapid probing system determines the OAM content of an underwater turbulent environment through frequency filtering and interferometry techniques. A complex amplitude function around a perfect vortex (PV) envelope is determined. By constraining the power measurement to the on-axis portion of the Fourier transformed field at the exit of the turbulent environment, this turbulence-dependent angular spectrum represents a matched filter of the complex media. The OAM mode spectrum is determined for each angular spectrum measured, allowing insight into the OAM content of the turbulence. Consecutive scans are conducted over a time interval such that the temporal characteristics of the OAM induced by the turbulence can be studied. The results indicate an OAM spectrum that evolves in time as the environment changes, with the average OAM around the PV fluctuating as well
Strategic Implications of Responses to Security and Privacy Challenges
No full textThis dissertation investigates strategic implications of information security and privacy for organizations and society in the contexts of ransomware and mobile apps. The first study examines how organizations’ disclosures of responses to ransomware attacks affect ransomware strain survival. Ransomware attacks force organizations to make consequential decisions regarding disclosure—whether to reveal ransom payments, negotiation attempts, or coordination with external stakeholders. This study investigates how these disclosure choices influence the survival of ransomware strains. Drawing on disclosure theory and institutional theory, we theorize that disclosure behavior is shaped by dual logics and audiences: strategic signaling towards attackers and institutional conformity aimed at regulators and professionals. Public ransom payment disclosures unintentionally signal profitability to attackers, reinforcing strain persistence. In contrast, disclosures of coordination with law enforcement reflect institutional compliance and bolster collective cybersecurity defenses. Disclosures of negotiation efforts serve as legitimacy signals that may attenuate the signaling impact of ransom payments. We test these mechanisms using a longitudinal dataset of 388 publicly disclosed ransomware attacks between 2018 and 2023 and estimate strain survival via Cox proportional hazards modeling. Results show that ransom payment disclosures increase strain survival, while coordination disclosures reduce it. Negotiation disclosures weaken the signaling effect of payments. Our study contributes to information systems and cybersecurity research by demonstrating how strategically and institutionally motivated disclosures influence adversarial dynamics and threat persistence. We offer implications for organizational disclosure strategy and cybersecurity governance.
The second study leverages Apple’s introduction of app tracking transparency to the iOS platform as an exogenous shock to estimate the impacts of mobile app platform transparency policy on apps’ in-app advertising and performance. Mobile apps use in-app advertising to attract new users in the hypercompetitive app platform marketplace. In-app advertising is highly targeted and relies on detailed user data, raising privacy concerns. In response, app platforms implement transparency policies requiring apps to disclose their data collection practices and seek user consent for tracking. This study examines how advertiser apps alter their ad platform scope, which is the extent to which an advertiser’s app uses different ad platforms for in-app advertising, in response to a platform transparency policy. We find that implementing iOS app tracking transparency significantly reduces advertiser apps’ ad platform scope, which reduces advertiser apps’ new downloads. We find that treatment effects on ad platform scope are heterogeneous, i.e., significant for (1) ad platforms that use alternative user tracking identifiers but not for those that update their advertising approaches, (2) higher cost ad platforms, and (3) apps with higher complexity. We rule out alternative explanations at the app level (i.e., an app’s targeted advertising capability and innovation capability) and ad platform level (i.e., ad platform reach).
Collectively, these studies provide an understanding of the challenges organizations face when responding to information security and privacy events. This dissertation clarifies the strategic landscape for organizations and provides a roadmap for responses that bolster cybersecurity and competitiveness
Designing Multilingual (Maker) Spaces: Exploring the Intersections of Play, Posthumanism, and Pre-kindergarten
No full textIn this dissertation, I explore the posthuman play literacies of multilingual makerspaces with four-year-olds, emphasizing the need for such a study while situating my arguments within the existing literature and outlining my methodological approach. Chapter One critiques the public 4-year-old kindergarten systems, arguing institutionalized cultural and linguistic ideologies restrict multilingual learners’ (MLs) opportunities for meaning-making. I draw on the raciolinguistic perspective (Flores & Rosa, 2015) and its intersection with a posthumanist paradigm (Braidotti, 2013), framing my research questions as lines of inquiry to guide the study. Key posthumanist literacies concepts are defined, highlighting the entanglement of literacies, discourses, materials, and humans.
Chapter Two reviews the literature on play literacies, innovative learning environments, and makerspaces while interweaving multilingualism. Chapter Three presents my design-based research (DBR) study, detailing four iterative phases of data collection and three approaches to analysis. I discuss the study context, participant roles, and address issues of trustworthiness and subjectivity. This chapter concludes with qualitative and post-qualitative data collection and analysis strategies, and acknowledgement of the study’s limitations.
Chapter Four describes the qualitative findings of this project, while Chapter Five looks at these data through post-qualitative inquiry. Findings across both chapters reveal how children’s literacies emerged through multimodal play, material entanglements, spatial intra-actions, and unexpected acts of resistance and joy. Materials and tools, such as cameras, scissors, and shelves, acted as co-authors in meaning-making, while documentation became both a pedagogical practice and relational force. Children composed with bodies, languages, and objects in ways that challenged static notions of literacy and participation.
Chapter Six offers a discussion across the two data analysis approaches and implications for theory, method, research, and practitioners. Implications include new ways of designing makerspaces that recognize materials as agents, documentation as inquiry, and literacy as a distributed, relational, and multilingual practice
Using Parent Empowerment Groups to Increase Academic Success in Kindergarten Multilingual Learners
Get PDFThis study examined how parent empowerment groups influence the academic success of kindergarten multilingual learners. With increasing immigration across the United States, schools need to work with families to ensure students develop the skills required for academic achievement at each level. The identified problem is that the current multilingual learner program at Boyd Matthews Elementary does not adequately meet parents’ needs in building a strong home-school connection, placing the full responsibility of learning on the school and leaving students without critical academic support at home. Parent empowerment groups were held with multilingual kindergarten parents to share practical strategies for supporting students in reading, writing, and math. The results did not show significant improvements on standardized tests such as iReady or ACCESS. However, qualitative data from surveys and follow-up phone calls with parents indicated that teaching families how to read, write, and engage with their children improved. Based on this work, it is essential to continue researching the impact of parent empowerment. Future studies should aim to strengthen two-way communication between families and teachers
Online Multiobjective Optimization
Get PDFOnline optimization (OO) is an iterative process of decision making under uncertainty. At every step, a decision is made before the outcome of this decision is known. For the online optimization model, the objective function is unknown at the time the decision is being made. It is very likely that the taken decision is not optimal, so the decision maker incurs a loss, called regret, in every iteration. The goal of the online optimization algorithm is to compute a decision at every step so that the overall regret cost is minimized. In particular, the average regret produced by an ideal online optimization algorithm should approach zero as the process continues for an infinite number of iterations. This indicates that the algorithm is learning
In a single-objective setting, the concept of regret and an online optimization algorithm are first proposed by Zinkevich (2003). Interest in OO has grown as learning algorithms have become more prominent and resulted in extensive studies for single-objective optimization problems. However, very few have studied online multiobjective optimization (OMO). In OMO, solutions are computed before the objective functions are revealed. As a result, these solutions are not Pareto for the associated offline multiobjective problem and incur a cost, measured by regret.
First, the online multiobjective problem is scalarized using the Weighted-Sum Method (Geoffrion, 1968) and results from online single-objective optimization for scalar regret are applied to these problems. Numerical results are included for various biobjective problems.
A new concept of set-based regret (SBR) for OMO, that generalizes the scalar regret to a multiobjective case, is introduced next. This SBR recognizes that a set of efficient (nondominated, Pareto-optimal) solutions rather than a single optimal solution is inherent to multiobjective optimization problems. The SBR is defined as the region between two sets associated with OMO: the online accumulated outcome set, that is computed for all online decisions taken at every iteration, and the offline Pareto set, that is computed after all objective functions become known. The proposed definition is not specific enough to be used in computation, so we utilize multiobjective performance indicators as means of computing the SBR. We design algorithms that minimize the performance indicator at every iteration and make the average SBR go to zero. Numerical results and comparisons are provided for these set-based algorithms. These numerical results feature examples of problems where the set-based algorithms have smaller regret than scalar regret counterparts.
Lastly, the newly designed OMO techniques are applied to an engineering design problem for an autonomous vehicle. The vehicle traverses an unknown path and must decide on its acceleration before the next segment of path is revealed. A biobjective model is derived that minimizes the elapsed time of the vehicle and minimizes the energy lost by the vehicle on each segment. Numerical results are included for the single-objective problem that minimizes the elapsed time. These results highlight that online optimization results in (i) better traversal times than choosing a fixed, constant acceleration for the vehicle over the entire path; (ii) traversal times that are not significantly worse in comparison to the times achieved with non-autonomous driving
Ecomorphological Diversification of Tooth Complexity in the Oral Jaws of Marine Teleostean Fishes
No full textTeeth are essential biological tools that function as a direct interface between predator and prey, thus providing essential insights into the evolutionary history and ecological diversity of vertebrates. Historically, studies on vertebrate dentitions have been qualitative and focused on mammals. More recently, quantitative methods have been developed that can reliably measure tooth surface complexity. These methods have been applied across both mammals and saurian reptiles to test for correlations with diet, leading to the conclusion that herbivorous species generally possess higher overall tooth complexity than any other dietary group. Surprisingly, the relationship between tooth complexity and diet in the most dentally diverse and speciose group of vertebrates—teleost fishes—remains unexplored. My dissertation addresses this knowledge gap by integrating phylogenetic comparative analyses with quantitative metrics of tooth complexity applied across 211 microCT scanned dentitions of predominantly reef-associated fish species. My first chapter develops a framework to apply a quantitative tooth complexity metric to fish dentitions. I conduct tests at various steps in the framework to determine best practices for quantifying fish tooth complexity, with the goal of providing an open-source guide for other comparative fish biologists to apply in their own studies. In my second chapter I apply this framework to investigate the relationship between dental complexity and tooth function, with the expectation that herbivory-associated tooth functions will promote higher complexity, as seen in mammals. Contrary to my prediction, I find that tooth count is a better predictor of dental complexity, with tooth eco-functional groups having little predictive power once tooth number is taken into account. In my third and final chapter, I compare tooth complexity variation across jaw regions to understand whether fish dentitions exhibit patterns of adaptation comparable to mammalian dentitions with complexity increasing posteriorly. Results from this study reveal that dental complexity exhibits considerable variation along the jaws, with the highest complexity found anteriorly, and is influenced both by relative jaw size and the functional ecological role of the dentition. This dissertation provides novel contributions in understanding how patterns of dental complexity evolve in fishes, and more broadly enhances our knowledge of ecomorphological diversification in vertebrates
Traces From the Abyss: Short-Form Video, Self-Reflexivity, and Holocaust Visual Rhetoric
No full textThis dissertation examines the potential role of short-form video as a new form of Holocaust representation in the 21st century. The need to forge connections between present/future generations and this chapter in history has taken on greater urgency, given that the last remaining survivors and eyewitnesses will soon be gone while white nationalist sentiment has swelled in recent years. This work addresses the question, How can we ensure that the Holocaust remains a contemporary subject, especially for young people? For decades, the public has relied on museums, movies, classroom lectures, and recorded testimonies to learn about the Holocaust. However, these long-trusted sources of knowledge have seen their influence decline in an age of increasing interactivity. Thanks to ever-evolving communication practices and the widespread availability of smartphones and other portable devices, people have more agency than ever regarding how they interact with media. Short- form video is one result of this, and because it is a democratized practice, more voices and perspectives can contribute to Holocaust knowledge, creating a more diverse understanding of this event while inviting digital users to play an active role in prolonging Holocaust memory
Item 2: Activity 1: Ethnocharette: The History and Imagined Futures of Puerto Rico
Get PDFFor this in-class activity, students work in small groups to conduct collaborative deep thinking on the history of Puerto Rico. To do this, they will first watch the Suncoast Emmy award-winning documentary, The Last Colony to learn about the history of Puerto Rico and its complex political relationship with the United States. Then, guided by the professor, they will use a modified version of the ethnocharette experimental pedagogy, developed by the University of California at Irvine’s Center for Ethnography, to understand, organize, and think more deeply about the themes of the documentary. Finally, they use this information to imagine possible new futures for Puerto Rico. In this activity, students watch a documentary and engage in an ethnocharette that facilitates synthetic, comparative, speculative, and imaginative thinking
Item 7: Assignment 2: Reactions to Constitution
Get PDFThis is a critical reading and reflection assignment designed to have students closely read politically-relevant documents, answer questions about arguments and evidence, and reflect on them
Item 1. Course Syllabus: History of Civic Engagement and Voting Rights Since Reconstruction, American History II
No full textThis syllabus is for a survey course that combines common themes in American history since 1865 with a specific focus on civic engagement and voting rights. It is centered around the stories of everyday Americans who participated in the Progressive Movement, the Civil Rights Movement, labor rights, and other turning points in American history related to civic engagement. The syllabus and course assignments highlight the role of oral history in preserving stories and introduce students to the methods and impact of historical advocates for justice. The goal is to help students reflect on their own roles in advocacy, allyship, and civic engagement, as well as connect past struggles with today’s challenges to better understand how one’s involvement in community is rooted in history