UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
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Item "And They Were Bedmates!": Travel and the Development of Privacy in Colonial America.(2023) Labor, Joanna; Brewer, Holly; History; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation is a study of how travelers, particularly white, elite travelers, thought about their lodgings over the course of the long eighteenth century, and how their lodging options changed as a result. Their writings about how they ate and where they slept reveal shifting cultural attitudes from both travelers and their hosts. Genteel travelers began to expect greater personal privacy, and private householders who formerly provided accommodations began to refuse to do so. The material culture of gentility spread quickly through the Atlantic world; elite homes became more compartmentalized places that allowed for people to develop new senses of personal privacy. While many Americans could partake in the trappings of gentility, they could not participate equally. Such differences in a standard of living created tensions between travelers and their hosts. Taverns, inns, and private homes were the main sources of lodging; however, most hosts were unable and increasingly unwilling to provide the individualized spaces that genteel travelers increasingly expected for their bodily privacy. Chapter one describes travelers and boarding in urban areas, and the role that boardinghouses played in affording travelers a measure of privacy. Chapter two discusses rural America during the colonial period, looking at why so many travelers ended up lodging in private homes despite their discomfort. Chapter three illustrates the standards of genteel travelers, and why they were often in opposition with the families who lived in the homes and taverns that they stayed in. Finally, chapter four discusses the reasons why householders and tavernkeepers began to deny travelers a berth overnight. If the first three chapters are about the power of elite travelers, the fourth chapter is about the power of householders to refuse entry in their homes, and the tools they used to reclaim their space from intrusive travelers. The conclusion discusses the emergence of the modern hotel, purpose-built buildings that both allowed travelers’ personal privacy as well as taking them out of domestic spaces. The rise of a tourist economy, coupled with changing ideas about who was allowed in domestic spaces, ensured both that travelers no longer sought respite in private homes, and that householders would not willingly allow strangers into their homes. However, the practice did not die out entirely, persisting in the backcountry frontier and in less settled areas where there was less travel infrastructure, into the nineteenth century.Item From Oversharing to Sharenting: How Experts Govern Parents and Their Social Media Use(2021) Kumar, Priya; Vitak, Jessica; Library & Information Services; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A newborn swaddled in a parent’s arms. A kindergartner posing on the first day of school. Such images, commonly found in family photo collections, now regularly appear on social media. At the same time, public discourse asks if—or sometimes asserts that—posting images online might put children’s privacy, dignity, and autonomy at risk. Prior research has documented the pressure, scrutiny, and judgment that parents, especially mothers, endure. It seems that parents’ use of social media is yet another cause for concern. How did this happen? This dissertation examines how power, manifesting as expertise, works through three fields of discourse to govern parents’ social media conduct. Grounding this project in post-structuralist epistemology, I study this question using the analytical technique of governmentality, which is a means of tracing how authorities intervene in the lives of individuals. First, I illustrate how a specific site of social media expertise, the once-popular blog STFU, Parents, constructs the problem of “oversharing” as a form of inappropriate social media use. Second, I explain, how news media expertise constructs the problem of “sharenting,” a portmanteau of the words “share” and “parenting,” as a form of risk to children. Third, I discern how academic expertise obliges parents to govern their own social media conduct by appealing to their subjectivity. In each field of discourse, I observe how expertise frames parents’ social media conduct as a matter of individual responsibility, even though much of what happens to information online lies outside individual control. I use this analysis to suggest future directions for research on social media and privacy that goes beyond the gendered public/private boundary and engages with the world as a site of entangled relations rather than individual entities.Item Mechanism Designs to Mitigate Disparities in Online Platforms: Evidence from Empirical Studies(2020) Mayya, Raveesh K; Viswanathan, Siva; Business and Management: Decision & Information Technologies; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)With the rising ubiquity of online platforms, there is an increasing focus on platforms’ role in enabling fair exchanges between buyers and sellers. Traditionally, platforms have inbuilt mechanisms such as screening or upfront data-gathering disclosure that encourage transactions between unfamiliar participants. Since such mechanisms can introduce power disparities between different sides, platforms have enacted policy changes to fix the imbalance. Extant literature hasn’t studied the unintended consequences of such policy changes. My dissertation seeks to fill this gap by examining platforms’ decisions to enact policy/mechanism changes that level the playing field by decentralizing choices for different sides. Using empirical studies, my dissertation seeks to causally identify the impact of such changes on outcomes for participants as well as for the platform. The first essay in my dissertation examines the impact Airbnb’s decision to make screening optional. There is increasing evidence that two-way screening mechanism has been used as a tool by users on the platform to discriminate against some users on the other side. In making screening optional, I find that African American hosts and female hosts are more likely to forgo screening and they benefit the most (in terms of occupancy, price and/or ratings) from forgoing screening, indicating that making screening optional can serve as a useful mechanism in helping alleviate reverse discrimination of hosts by guests. The second essay studies platforms’ attempts to provide smartphone users with better choice over which sensitive information can mobile apps access. In particular, I examine the timing of mobile apps' decisions to upgrade to Android 6.0, which restricts the ability of mobile apps from seeking blanket permissions to sensitive user information at download, instead requiring them to request à la carte permissions at run-time. I find that apps that over-seek (access information that are non-essential to their functionality) sensitive information from users strategically delay upgrading to Android 6.0. However, these apps suffer popularity and reputational costs in the Android marketplace. Collectively, the findings in my dissertation provides valuable theoretical as well as practical insights about the welfare implications of choice decentralization on all sides in online platforms, not just the intended side.Item Quality and Inequity in Digital Security Education(2019) Redmiles, Elissa M; Mazurek, Michelle L; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Few users have a formal, authoritative introduction to digital security. Rather, digital security skills are often learned haphazardly, as users filter through an overwhelming quantity of security education from a multitude of sources, hoping they're implementing the right set of behaviors that will keep them safe. In this thesis, I use computational, interview, and survey methods to investigate how users learn digital security behaviors, how security education impacts security outcomes, and how inequity in security education can create a digital divide. As a first step toward remedying this divide, I conduct a large-scale measurement of the quality of the digital security education content (i.e., security advice) that is available to users through one of their most cited sources of education: the Internet. The results of this evaluation suggest a security education ecosystem in crisis: security experts are unable or unwilling to narrow down which behaviors are most important for users' security, leaving end-users -- especially those with the least resources -- to attempt to implement the hundreds of security behaviors advised by educational materials.Item Modeling, Quantifying, and Limiting Adversary Knowledge(2015) Mardziel, Piotr; Hicks, Michael; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Users participating in online services are required to relinquish control over potentially sensitive personal information, exposing them to intentional or unintentional miss-use of said information by the service providers. Users wishing to avoid this must either abstain from often extremely useful services, or provide false information which is usually contrary to the terms of service they must abide by. An attractive middle-ground alternative is to maintain control in the hands of the users and provide a mechanism with which information that is necessary for useful services can be queried. Users need not trust any external party in the management of their information but are now faced with the problem of judging when queries by service providers should be answered or when they should be refused due to revealing too much sensitive information. Judging query safety is difficult. Two queries may be benign in isolation but might reveal more than a user is comfortable with in combination. Additionally malicious adversaries who wish to learn more than allowed might query in a manner that attempts to hide the flows of sensitive information. Finally, users cannot rely on human inspection of queries due to its volume and the general lack of expertise. This thesis tackles the automation of query judgment, giving the self-reliant user a means with which to discern benign queries from dangerous or exploitive ones. The approach is based on explicit modeling and tracking of the knowledge of adversaries as they learn about a user through the queries they are allowed to observe. The approach quantifies the absolute risk a user is exposed, taking into account all the information that has been revealed already when determining to answer a query. Proposed techniques for approximate but sound probabilistic inference are used to tackle the tractability of the approach, letting the user tradeoff utility (in terms of the queries judged safe) and efficiency (in terms of the expense of knowledge tracking), while maintaining the guarantee that risk to the user is never underestimated. We apply the approach to settings where user data changes over time and settings where multiple users wish to pool their data to perform useful collaborative computations without revealing too much information. By addressing one of the major obstacles preventing the viability of personal information control, this work brings the attractive proposition closer to reality.Item Energy Efficiency and Privacy Protection in Cellular Networks(2014) Ta, Tuan Minh; Baras, John S; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Smartphones have become an essential part of our society. The benefits of having an always present, highly capable device cannot be overstated. As more aspects of our life depend on our smartphones, it is more important than ever to ensure the availability of those devices. However, their big advantages also come with big risks. The fact that we have our smartphones with us all the time means that it is easier than ever to collect our information, sometimes without our consent. In this dissertation, we study the two pressing concerns in cellular communications: energy efficiency and privacy protection. We focus on LTE networks, the current most advanced global standard for cellular communications. In the first part of the dissertation, we study the energy efficiency problem from both device and network perspectives. From the device point of view, we introduce a new angle to address the battery life concern. We recognize that the value of battery for the users is not always the same, and that it depends on the user usage. We also identify, and show in real network, diversity of usage, the phenomenon that at any instant, there is a diverse distribution of smartphone usage among cellular users. We propose ``Battery Deposit Service'' (BDS), a cooperative system which makes use of device-to-device (D2D) communications underlaying cellular networks to provide energy sharing in the form of load sharing. We design BDS to take advantage of diversity of usage to maximize the utility of smartphone battery. We show that our system increases battery life of cellular users, at almost no cost to the rest of the network. BDS is designed to be compatible to LTE architecture. From the network point of view, we design an energy efficient D2D relay system underlaying LTE networks. We minimize transmission power of smartphones by considering relay selection, resource allocation and power control. The overall problem is prohibited due to its exponential search space. We develop a divide-and-conquer strategy which splits the overall problem into small sub-problems. We relate these sub-problems to well-studied graph theoretic problems, and take advantage of existing fast algorithms. We show that our algorithms meet the runtime requirement of real-time LTE operations. In the second part of the dissertation, we address a privacy concern in LTE networks. In particular, we show that user location can be leaked in current LTE paging architecture. We propose a mechanism based on signal processing to remedy this vulnerability. Our method makes use of physical layer identification, which are low-power tags embedded on the wireless waveform, to signal paging messages to user devices. We show that our method is stealthy and robust, and that it mitigates the aforementioned privacy issue.Item Prediction, evolution and privacy in social and affiliation networks(2011) Zheleva, Elena; Getoor, Lise; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In the last few years, there has been a growing interest in studying online social and affiliation networks, leading to a new category of inference problems that consider the actor characteristics and their social environments. These problems have a variety of applications, from creating more effective marketing campaigns to designing better personalized services. Predictive statistical models allow learning hidden information automatically in these networks but also bring many privacy concerns. Three of the main challenges that I address in my thesis are understanding 1) how the complex observed and unobserved relationships among actors can help in building better behavior models, and in designing more accurate predictive algorithms, 2) what are the processes that drive the network growth and link formation, and 3) what are the implications of predictive algorithms to the privacy of users who share content online. The majority of previous work in prediction, evolution and privacy in online social networks has concentrated on the single-mode networks which form around user-user links, such as friendship and email communication. However, single-mode networks often co-exist with two-mode affiliation networks in which users are linked to other entities, such as social groups, online content and events. We study the interplay between these two types of networks and show that analyzing these higher-order interactions can reveal dependencies that are difficult to extract from the pair-wise interactions alone. In particular, we present our contributions to the challenging problems of collective classification, link prediction, network evolution, anonymization and preserving privacy in social and affiliation networks. We evaluate our models on real-world data sets from well-known online social networks, such as Flickr, Facebook, Dogster and LiveJournal.Item Information Technology and Its Transformational Effect on the Health Care Industry(2007-04-25) Angst, Corey M; Agarwal, Ritu; Business and Management: Decision & Information Technologies; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation examines the adoption of health IT by addressing the barriers to adoption from the perspective of multiple stakeholders. I examine three different phenomena using alternative methodologies and theoretical lenses. Essay 1: The Impact of Firm Characteristics and Spatial Proximity on the Diffusion of Electronic Medical Records: A Hazard Modeling Analysis. This study, positioned at the inter-organizational level, draws upon adoption and diffusion literature to predict the likelihood of EMR adoption by hospitals. I theorize that adoption is driven by factors such as the concentration and experience with complementary HIT and an environmental factor, spatial proximity. Using a hazard model fitted to data from a sample drawn from almost 4,000 hospitals, I find support for a positive relationship between IT concentration and likelihood of adoption. I also find that spatial proximity explains variance in adoption and that its effect diminishes as distance increases. Essay 2: Isolating the Effects of IT on Performance: An Empirical Test of Complementarities and Learning. An issue at the organizational level is whether benefits result from investment in HIT. I apply a knowledge-based lens to the examination of IT adoption and process-level value, incorporating the effects of learning occurring through complementary IT adoption. I test hypotheses using data from almost 400 nationally-representative hospitals matched with quality and financial performance data and find that learning associated with more experience with IT leads to superior performance. Essay 3: Adoption of Electronic Medical Records in the Presence of Privacy Concerns: The Elaboration Likelihood Model and Individual Persuasion. At the individual level, privacy concerns can inhibit the adoption of EMRs. I draw from literature on attitude change to develop hypotheses that individuals can be persuaded to support the use, and ultimately opt-in to EMRs, even in the presence of significant privacy concerns if compelling arguments about the value of EMRs are presented. Using a quasi-experimental methodology, I find that privacy concerns interact with argument framing and issue involvement to affect attitudes toward the use of EMRs. In addition, results suggest that attitude towards EMR use and CFIP directly impact the likelihood of adoption of EMR technology.Item Private Communications with Chaotic Code Division Multiple Access: Performance Analysis and System Design(2004-08-04) Hwang, Yeong-Sun; Papadopoulos, Haralabos C; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In this dissertation we develop a class of pseudochaotic direct-sequence code division multiple access (DS/CDMA) systems that can provide private and reliable communication over wireless channels. These systems exploit the sensitive dependence of chaotic sequences on initial conditions together with the presence of channel noise to provide a substantial gap between the bit error probabilities achievable by intended and unintended receivers. We illustrate how a desired level of private communication can be achieved with a systematic selection of the system parameters. This type of privacy can be readily combined with traditional encryption methods to further ensure the protection of information against eavesdroppers. The systems we propose employ linear modulation of each user's symbol stream on a spreading sequence generated by iterating a distinct initial condition through a pseudochaotic map. We evaluate and compare the uncoded probability of error (Pr(e)) achievable by intended receivers that know the initial condition used to generate the spreading sequence to the associated Pr(e) of unintended receivers that know the modulation scheme but not the initial condition. We identify the map attributes that affect privacy, and construct algorithmic design methods for generating pseudochaotic spreading sequences that successively and substantially degrade the unintended user performance, while yielding intended user performance similar to that of conventional DS/CDMA systems. We develop efficient metrics for quantifying the unintended receiver Pr(e) and prove that it decays at a constant rate of 1/sqrt(SNR) in AWGN and fading channels. In addition, we show that this decaying rate is independent of the available degrees of diversity in fading channels, showing in the process that only intended receivers can harvest the available diversity benefits. Moreover, we illustrate that the pseudochaotic DS/CDMA systems can provide reliable multiuser communication that is inherently resilient to eavesdropping, even in the worst-case scenarios where all receivers in a network except the intended one collude to better eavesdrop on the targeted transmission. We also develop optimized digital implementation methods for generating practical pseudochaotic spreading sequences that preserve the privacy characteristics associated with the underlying chaotic spreading sequences.