A generalized temporal role based access control (GTRBAC) model that captures an exhaustive set of temporal constraint needs for access control has been proposed. GTRBAC’s language constructs allow one to specify various temporal constraints on role, user-role assignments and role-permission assignments. We present the notion of different types of role hierarchies based on the permission-inheritance and role activation semantics. In particular, we look at how new hierarchical relations between a pair of roles that are not directly related can be derived through other well-defined hierarchically related roles. When the different hierarchy types coexist in a role hierarchy, inferring such derived hierarchical relations between a pair of roles can be complex. The results presented provide a basis for formally analyzing the derived inheritance and activation semantics between every pair of roles in a hierarchy.

Data anonymization techniques based on the k-anonymity model have been the focus of intense research in the last few years. Although the k-anonymity model and the related techniques provide valuable solutions to data privacy, current solutions are limited only to static data release (i.e., the entire dataset is assumed to be available at the time of release). While this may be acceptable in some applications, today we see databases continuously growing everyday and even every hour. In such dynamic environments, the current techniques may suffer from poor data quality and/or vulnerability to inference. In this paper, we analyze various inference channels that may exist in multiple anonymized datasets and discuss how to avoid such inferences. We then present an approach to securely anonymizing a continuously growing dataset in an efficient manner while assuring high data quality.

Location-based services, such as finding the nearest gas station, require users to supply their location information. However, a user’s location can be tracked without her consent or knowledge. Lowering the spatial and temporal resolution of location data sent to the server has been proposed as a solution. Although this technique is effective in protecting privacy, it may be overkill and the quality of desired services can be severely affected. In this paper, we suggest a framework where uncertainty can be controlled to provide high quality and privacy-preserving services, and investigate how such a framework can be realized in the GPS and cellular network systems. Based on this framework, we suggest a data model to augment uncertainty to location data, and propose imprecise queries that hide the location of the query issuer and yields probabilistic results. We investigate the evaluation and quality aspects for a range query. We also provide novel methods to protect our solutions against trajectory-tracing. Experiments are conducted to examine the effectiveness of our approaches.

Electronic workplace surveillance is raising concerns about privacy and fairness. Integrating research on electronic performance monitoring, procedural justice, and organizational privacy, the author proposes a framework for understanding reactions to technologies used to monitor and control employees. To test the framework’s plausibility. temporary workers performed computer/Web-based tasks under varying levels of computer surveillance. Results indicated that monitoring job-relevant activities (relevance) and affording those who were monitored input into the process (participation) reduced invasion of privacy and enhanced procedural justice. Moreover, invasion of privacy fully mediated the effect of relevance and partially mediated the effect of participation on procedural justice. The findings are encouraging for integrating theory and research on procedural justice and organizational privacy.

We use uncertainty management theory (Lind & Van den Bos, 2002) as a framework to examine how the members of computer-mediated groups differ from those of face-to-face groups in their reactions to unfair events. Due to informational uncertainty surrounding interpersonal interactions in computer-mediated groups, fairness from authorities is more salient to the members of computer-mediated groups. Consequently, the members of computer-mediated groups tend to, in general, react more negatively to unfair events than do those of face-to-face groups. Moreover, the difference between the members of computer-mediated groups and face-to-face groups, in reactions to unfair events, increases over time. We present a laboratory study where we found support for these arguments.

The globalization of telecommunicative ties between nations is studied from a heterogenization perspective. A theoretical model inspired by Appadurai’s “disjuncture hypothesis,” which stipulates that global flows of communication are multidimensional and reinforce regional/local identities, is tested empirically on an international voice traffic dataset. Spatial-statistical measures (global and local versions of Moran’s I) indicate that countries that share the same linguistic (English, Spanish, or French) or civilizational (Catholic, Protestant, and Buddhist–Hindu) background are more likely to be each other’s “telecommunicative neighbors” and that this tendency has increased over time (1989–1999).

Numerous studies have identified links among culture, user preferences, and Web site usability. Most of these studies were reports of findings from a behavioral perspective in explaining how cultural factors affect processes of Web-related content design and use. Based on the research of Vygotsky and Nisbett, the authors propose a broader model, referred to as “cultural cognition theory,” by which Web design, like other types of information production, is seen as being shaped by cultural cognitive processes that impact the designers’ cognitive style. This study explores issues related to Web designers’ cultural cognitive styles and their impact on user responses. The results of an online experiment that exposed American and Chinese users to sites created by both Chinese and American designers indicate that users perform information-seeking tasks faster when using Web content created by designers from their own cultures.

The article refines the view that the Internet is increasingly incorporated in everyday life, concluding that the new medium has been partially integrated in the “communication infrastructure” of English-speaking Los Angeles neighborhoods. Here, Internet connectedness is associated with civic participation and indirectly contributes to “belonging” to a residential community. However, in predominantly Asian and Latino areas, the Internet is disengaged from communication environments that lead to belonging, being associated with mainstream media. In these communities its contribution is contradictory; although it probably contributes to the process of ethnic assimilation, it might also lead to disengagement of most educated and technologically savvy residents from their neighborhoods. A possible “magnifying glass effect” is proposed as explanation for the differential integration of new media in community life.

Claims about the emergence of a new type of social aggregation—“virtual community”—cover a type of ideological discourse about social interactions. The main cultural resource fueling this ideology is the counterculture and its social project. Virtual community, both as a discursive and as a social practice, is a culmination rather than a resolution of the modern conflict between community and individuality. Presenting virtual community as a panacea for modern social tensions, especially that between individualistic and communitarian ideals, hides from sight not only some of the negative aspects of on-line social life (cliquish behavior and incivility) but also the role played by communication technology in fragmenting modern society.

Virtual communities are discussed as expressions of the modern tension between individuality and community, emphasizing the role that counterculture and its values played in shaping the virtual community project. This article analyzes postings to the WELL conferences and the online groups that served as incubators and testing ground for the term “virtual community,” revealing how this concept was culturally shaped by the countercultural ideals of WELL users and how the tension between individualism and communitarian ideals was dealt with. The overarching conclusion is that virtual communities act both as solvent and glue in modern society, being similar to the “small group” movement.

Studies of international telecommunication networks in past years have found increases in density, centralization, and integration. More recent studies, however, have identified trends of decentralization and regionalization. The present research examines these structural changes in international telephone traffic among 110 countries between 1989 and 1999. It examines the competing theoretical models of core-periphery and cluster structures. The initial results show lowered centralization and inequality in the network of international telecommunications traffic. Statistical p* procedures demonstrate significant interactions within countries in blocks of similar economic development status, geographic region, and telecommunications infrastructure development status. Specifically, countries with less developed economic and telecommunications status showed significant increases in tendencies to connect to each other and to reciprocate ties. Altogether, the result supports the idea that the global telecommunications network is moving toward a more diversified structure with the emergence of cohesive and interconnected subgroups. The findings have implications for global digital divide and developmental gap issues.

The paper analyzes the 48 contiguous states of the Union and their ability to create and maintain online communities (Yahoo! groups). Multiple regression analysis indicates that the number of online groups and overall amount of online activity increase with amount of social capital. Also, ethnic homogeneity positively influences the number of online groups, while population density and number of IT workers are positively associated with level of online activity. in broad terms, the analyses support the idea that the Internet strengthens offline interaction, sociability online building on sociability offline.

In this demo, we present Nile-PDT, a Phenomenon Detection and Tracking framework using the Nile data stream management system. A phenomenon is characterized by a group of streams showing similar behavior over a period of time. The functionalities of Nile-PDT is split between the Nile server and the Nile-PDT application client. At the server side, Nile detects phenomenon candidate members and tracks their propagation incrementally through specific sensor network operators. Phenomenon candidate members are processed at the client side to detect phenomena of interest to a particular application. Nile-PDT is scalable in the number of sensors, the sensor data rates, and the number of phenomena. Guided by the detected phenomena, Nile-PDT tunes query processing towards sensors that heavily affect the monitoring of phenomenon propagation.

Ranking queries, also known as top-k queries, produce results that are ordered on some computed score. Typically, these queries involve joins, where users are usually interested only in the top-k join results. Top-k queries are dominant in many emerging applications, e.g., multimedia retrieval by content, Web databases, data mining, middlewares, and most information retrieval applications. Current relational query processors do not handle ranking queries efficiently, especially when joins are involved. In this paper, we address supporting top-k join queries in relational query processors. We introduce a new rank-join algorithm that makes use of the individual orders of its inputs to produce join results ordered on a user-specified scoring function. The idea is to rank the join results progressively during the join operation. We introduce two physical query operators based on variants of ripple join that implement the rank-join algorithm. The operators are nonblocking and can be integrated into pipelined execution plans. We also propose an efficient heuristic designed to optimize a top-k join query by choosing the best join order. We address several practical issues and optimization heuristics to integrate the new join operators in practical query processors. We implement the new operators inside a prototype database engine based on PREDATOR. The experimental evaluation of our approach compares recent algorithms for joining ranked inputs and shows superior performance.