Given the popularity of Java, extending the standard Java virtual machine (JVM) to become cluster-aware effectively brings the vision of transparent horizontal scaling of applications to fruition. With a set of cluster-wide JVMs orchestrated as a virtually single system, thread-level parallelism in Java is no longer confined to one multiprocessor. An unmodified multithreaded Java application running on such a Distributed JVM (DJVM) can scale out transparently, tapping into the vast computing power of the cluster. While this notion creates an easy-to-use and powerful parallel programming paradigm, research on DJVMs has remained largely at the proof-of-concept stage where successes were proven using trivial scientific computing workloads only. Real-life Java applications with commercial server workloads have not been well-studied on DJVMs. Their natures including complex and sometimes huge object graphs, irregular access patterns and frequent synchronizations are key scalability hurdles. To design a scalable DJVM for real-life applications, we identify three major unsolved issues calling for a top-to-bottom overhaul of traditional systems. First, we need a more time- and space-efficient cache coherence protocol to support fine-grained object sharing over the distributed shared heap. The recent prevalence of concurrent data structures with heavy use of volatile fields has added complications to the matter. Second, previous generations of DJVMs lack true support for memory-intensive applications. While the network-wide aggregated physical memory can be huge, mutual sharing of huge object graphs like Java collections may cause nodes to eventually run out of local heap space because the cached copies of remote objects, linked by active references, can’t be arbitrarily discarded. Third, thread affinity, which determines the overall communication cost, is vital to the DJVM performance. Data access locality can be improved by collocating highly-correlated threads, via dynamic thread migration. Tracking inter-thread correlations trades profiling costs for reduced object misses. Unfortunately, profiling techniques like active correlation tracking used in page-based DSMs would entail prohibitively high overheads and low accuracy when ported to fine-grained object-based DJVMs. This dissertation presents technical contributions towards all these problems. We use a dual-protocol approach to address the first problem. Synchronized (lock-based) and volatile accesses are handled by a home-based lazy release consistency (HLRC) protocol and a sequential consistency (SC) protocol respectively. The two protocols’ metadata are maintained in a conflict-free, memory-efficient manner. With further techniques like hierarchical passing of lock ownerships, the overall communication overheads of fine-grained distributed object sharing are pruned to a minimal level. For the second problem, we develop a novel uncaching mechanism to safely break a huge active object graph. When a JVM instance runs low on free memory, it initiates an uncaching policy, which eagerly assigns nulls to selected reference fields, thus detaching some older or less useful cached objects from the root set for reclamation. Careful orchestration is made between uncaching, local garbage collection and the coherence protocol to avoid possible data races. Lastly, we devise lightweight sampling-based profiling methods to derive inter-thread correlations, and a profile-guided thread migration policy to boost the system performance. Extensive experiments have demonstrated the effectiveness of all our solutions. / published_or_final_version / Computer Science / Doctoral / Doctor of Philosophy

Throughout history, creature-based content has been a highly valued source of entertainment. With the introduction of evolved virtual creatures (or EVCs) by Karl Sims in 1994, a new source of creature content became available. Despite their immediate appeal, however, EVCs still lag far behind their natural counterparts: Neither their morphology nor their behavior is sufficiently complex. This dissertation presents three contributions to address this problem. First, the ESP system, which combines a human-designed syllabus with encapsulation and conflict-resolution mechanisms, is used to approximately double the state of the art in behavioral complexity for evolved virtual creatures. Second, an extension to ESP is presented that allows full morphological adaptation to continue beyond the initial skill. It produces both a greater variety of solutions and solutions with higher fitness. Third, a muscle-drive system is demonstrated to embody a significant degree of physical intelligence. It increases morphological complexity and reduces demands on the brain, thus freeing resources for more complex behaviors. Together, these contributions bring evolved virtual creatures, in both action and form, a significant step closer to matching the entertainment value of creatures from the real world. / text

While online virtual worlds draw increasingly wider audiences of players and scholars alike, offline games continue to evolve into more complex and socially layered forms as well. This dissertation argues that virtual worlds need not exist as online, digital environments alone and probes three genres of non-digital gaming for evidence of the virtual: tabletop role-playing games, murder-mystery events, and localized alternate reality games. More broadly, then, this dissertation is about deliberate make-belief: practiced by adults, taken seriously by participants, engaged with for long hours at a time, performed in public, and integrated into everyday social relationships. Drawing on scholars who study games as social activities (McGonigal 2006, Montola 2012) and social institutions (Goffman 1974, Searle 1995), I present three ethnographic case studies that illustrate how complex forms of social gaming can conjure and sustain environments best understood as analog virtual worlds. Through the widespread use of mobile technologies and the concerted efforts of innovators, game spaces are increasingly permeating our everyday lives on- and offline. This dissolving boundary demands anthropologists to revisit questions of how, where, and with whom we play games. Dovetailing Martin Heidegger’s notions of worlding and poiesis to the semiotics of C.S. Peirce, this dissertation investigates how new forms of social gaming demonstrate the same qualities of shared intentionality, intersubjectivity, and performance essential to the production of new social meaning and cultural forms. Following, I situate the bold ethnographic case studies of make-belief in dialogue with scholars who figure exclusively online virtual worlds (Castronova 2005, Taylor 2006, Boellstorff 2008) and argue that analyzing both on- and offline virtual worlds together can help scholars better understand the fundamental nature of social interaction and shared intentionality, those everyday mechanisms that both sustain personal relationships on the one hand and maintain our broadest and most serious social institutions on the other.

Client devices operating at the edges on the Internet, in homes, cars, offices, and elsewhere, are highly heterogeneous in terms of their hardware configurations, form factors, and capabilities, ranging from small sensors to wearable and mobile devices, to the stationary ones like smart TVs and desktop machines. With recent and future advances in wireless networking allowing all such devices to interact with each other and with the cloud, it becomes possible to combine and augment capabilities of individual devices via services running at the edge - in edge clouds - and/or via services running in remote datacenters. The virtual platform approach to combining and enhancing such devices developed in this research makes possible the creation of innovative end user services, using low-latency communications with nearby devices to create for each end user exactly the platform needed for current tasks, guided by permissions and policies controlled by remote, cloud-resident social network services (SNS). To end users, virtual platforms operate beyond the limitations of individual devices, as natural extensions of those devices that offer improved functionality and performance, with ease-of-use provided by cloud-level global context and knowledge.

published_or_final_version / abstract / Architecture / Doctoral / Doctor of Philosophy

Purpose: This paper explores the use of blogs as a platform for providing reference service, and discusses Lyceum, an open source software project from ibiblio.org, for this purpose. Design/methodology/approach: The following topics are explored: the evolution of libraries' uses of blogs, the advantages of conducting the reference transaction as a collaborative effort, and the use of blogs as an environment that fosters collaboration. The argument is made that blogs may be used to good effect in reference services Findings: It is argued that blogs may be used to good effect in reference services. Lyceum, an open source blogosphere application, is discussed as an environment for blog-based reference service. Originality/value: To date, blogs are not being used by a library reference services, and by few online reference service unaffiliated with libraries. This paper will be useful to libraries and other reference services interested in conducting the reference transaction as a community effort.

Research has repeatedly shown that computer-mediated communications (CMC) lead to higher levels of disclosure of personal information (Tidwell and Walther 2002). Recent studies have examined the role of increasingly common social media and social network services (SNS) on disclosure in a variety of contexts (Mazer et al. 2007; Tufekci 2008). The combination of personal demographic data, taste preferences, public disclosure of friend networks and now increasing usage of tools for instantly updating status (e.g., Twitter, Facebook) has, we believe, fundamentally altered users' understanding of the temporality of information and its (semi-)permanence. This study investigates users' willingness to disclose information with respect to how long ago that information may have been created or captured. Users were more willing to share items as time passed. Potentially, a "Later Button" should be put into practice to address this latent willingness (40% of sharing scenarios) to disclose information at a later date.

Purpose: This paper explores the use of blogs as a platform for providing reference service, and discusses Lyceum, an open source software project from ibiblio.org, for this purpose. Design/methodology/approach: The following topics are explored: the evolution of libraries' uses of blogs, the advantages of conducting the reference transaction as a collaborative effort, and the use of blogs as an environment that fosters collaboration. The argument is made that blogs may be used to good effect in reference services Findings: It is argued that blogs may be used to good effect in reference services. Lyceum, an open source blogosphere application, is discussed as an environment for blog-based reference service. Originality/value: To date, blogs are not being used by a library reference services, and by few online reference service unaffiliated with libraries. This paper will be useful to libraries and other reference services interested in conducting the reference transaction as a community effort.

This 105-page report is deposited with permission of the Digital Library Federation which retains copyright. It is freely available in html and pdf formats at the DLF Web site or may be purchased in softcover edition for $20 from DLF. / This report, commissioned by DLF, provides an overview of a diverse set of more than thirty digital library aggregation services, organizes them into functional clusters, and then evaluates them more fully from the perspective of an informed user. Most of the services under review rely wholly or partially on the Protocol for Metadata Harvesting of the Open Archives Initiative (OAI-PMH). Each service is annotated with its organizational affiliation, subject coverage, function, audience, status, and size. Critical issues surrounding each of these elements are presented in order to provide the reader with an appreciation of the nuances inherent in seemingly straightforward factual information, such as "audience" or "size." Each service is then grouped into one of five functional clusters: open access e-print archives and servers; cross-archive search services and aggregators; from digital collections to digital library environments; from peer-reviewed "referratories" to portal services; specialized search engines. This publication was deposited with permission of the publisher (Digital Library Federation Council on Library and Information Resources Washington, DC.).

This thesis proposes a new genre of theater that combines participatory and interactive narratives with virtual reality technologies and traditional theatrical elements to create a form that is capable of responding to the growing desire for interactive entertainment mediums. A series of participatory narrative events, including traditional theater productions, interactive narrative/drama and role-playing games, are analyzed for their potentialities and limitations. These elements are then used to respond to scholarly writings concerning the problems of participatory narrative forms. From this analysis conclusions are drawn about the necessary elements needed to create this new genre of theater, termed interactive virtual theater, or IVT. The elements are then synthesized into a hypothetical picture of what the IVT of the future might look like.