840524
Newsgroup Crowds and AuthorLines: visualizing the activity of individuals in conversational cyberspaces
We discuss the design, implementation and evaluation of two related visualizations of authors' activities in Usenet newsgroups. Current Usenet news browsers focus on messages and thread structures while disregarding valuable information about the authors of messages and the participants of the various discussions. Newsgroup Crowds graphically represents the population of authors in a particular newsgroup. Authors are displayed according to the number of messages they contribute to each thread and the number of different days they appear in the space, illustrating and contrasting the interaction patterns of participants within the newsgroup. AuthorLines visualizes a particular author's posting activity across all newsgroups over a period of one year. This visualization reveals temporal patterns of thread initiation and reply that can broadly characterize the roles authors play in Usenet. We report the results of a user study that explored the value of these interfaces for developing high-level awareness of the activity and population in these conversational spaces. We suggest that interfaces that convey information about the social histories of populations and individuals may support better selection and evaluation of newsgroup content.
5888435
Visualization components for persistent conversations
An appropriately designed interface to persistent, threaded conversations could reinforce socially beneficial behavior by prominently featuring how frequently and to what degree each user exhibits such behaviors. Based on the data generated by the Netscan data-mining project [9], we have developed a set of tools for illustrating the structure of discussion threads like those found in Usenet newsgroups and the patterns of participation within the discussions. We describe the benefits and challenges of integrating these tools into a multi-faceted dashboard for navigating and reading discussions in social cyberspaces like Usenet and related interaction media. Visualizations of the structure of online discussions have applications for research into the sociology of online groups as well as possible interface designs for their members.
10633849
Assessing differential usage of usenet social accounting meta-data
We describe a usage study of NetscanTech, a system that generates and publishes daily a range of social metrics across three dimensions: newsgroup, author, and thread, for a set of approximately 15,000 technical newsgroups in Usenet. We bring together three interlinked datasets: survey data, usage log data and social accounting data from Usenet participation, to triangulate the relationship between various user roles and differential usage of social metrics in NetscanTech. We found our most frequent users focused on information related to individual authors far more than any other information provided. In contrast, users that visited less frequently focused more on information related to newsgroups and viewing newsgroup metrics. Our results suggest features that designers and developers of online communities may wish to include in their interfaces to support the cultivation of different community roles.
402019
Conversation trees and threaded chats
Chat programs and instant messaging services are increasingly popular among Internet users. However, basic issues with the interfaces and data structures of most forms of chat limit their utility for use in formal interactions (like group meetings) and decision-making tasks. In this paper, we discuss Threaded Text Chat, a program designed to address some of the deficiencies of current chat programs. Standard forms of chat introduce ambiguity into interaction in a number of ways, most profoundly by rupturing connections between turns and replies. Threaded Chat presents a solution to this problem by supporting the basic turn-taking structure of human conversation. While the solution introduces interface design challenges of its own, usability studies show that users' patterns of interaction in Threaded Chat are equally effective, but different (and possibly more efficient) than standard chat programs.
52872904
Simulative analysis of dynamic scheduling heuristics for reconfigurable computing of parallel applications
The demand for processing power has been ever increasing with the growth of high-performance computing (HPC) applications and so have the constraints restricting the solutions to such requirements. High-performance distributed and parallel computing and custom-built, hardware-based computing have attempted to address this problem with some success but at a substantial cost. Recently, systems augmented with Field-Programmable Gate Arrays (FPGAs) offering a fusion of traditional parallel and distributed machines with customizable and dynamically reconfigurable hardware have emerged as a cost-effective alternative to traditional systems. However, providing a robust runtime environment for such systems to which HPC users have become accustomed has been fraught with numerous challenges. Dynamic scheduling of large-scale HPC applications in such parallel reconfigurable computing (RC) environments is one such challenge and has not been sufficiently studied to our knowledge. In this paper, we simulatively analyze the performance of several common HPC scheduling heuristics that can be used by an automated job management service to schedule application tasks on a parallel RC system. We also present a performance prediction model which the scheduling heuristics employ to schedule several common HPC applications on a collection of typical FPGA processing platforms.
835724
Database Support for Exploring Criminal Networks
An established method of comprehending the data gathered thus far in a criminal investigation is to incrementally visualize it as a network, such as in the diagram displayed below which is referred to as a link chart, to ascertain if, and how, objects of interest are connected.
26831752
Incrementally visualising criminal networks
Understanding the information gathered thus far in a criminal investigation is of great importance, particularly in terms of guiding its future course. Since the late 1980's the use of software tools to provide visualisations of this information has become increasingly common. The objective of such tools is to provide, in a readily comprehensible way, the social network of all the people involved. This may include the victims, suspects, witnesses, acquaintances and locations of interest in the investigation such as workplaces or nightclubs. Such diagrammatic representations often provide the focus for discussion among the investigating team and are incrementally added to as new facts are discovered. In this paper we present a brief overview of this important subject area and discuss how such software products could be further enhanced. We also present an example that illustrates the basic principles using a demonstrator we developed.
5639011
A Characterization of Lazy and Eager Semantic Solutions to the Linda Predicates Ambiguity Problem
The problems associated with Linda predicate operations inp() and rdp() are well known but not always well understood. One problem, from a purely academic standpoint, is that of semantic ambiguity in the case of failure. Despite this problem, commercial tuple space implementations all provide some version of the Linda predicate operations, and thus, problems concerning safety and liveness arise. Solutions to address these problems range from proposing extensions to an existing model of computation (CSP) to proposing alternative definitions for the Linda predicate operations themselves. While these solutions may at first appear unrelated, it is possible to relate these two disparate approaches in the context of lazy and eager semantics. The benefits of this characterization include a clearer understanding of the Linda predicates ambiguity problem, two respective solutions to this problem, and the importance of considering both lazy and eager semantic perspectives as techniques for problem solving in parallel and distributed systems.
7589048
Security considerations when designing a distributed file system using object storage devices
We present the design goals that led us to developing a distributed object-based secure file system, Brave. Brave uses mutually authenticated object storage devices, SCARED, to store file system data. Rather than require a new authentication infrastructure. we show how we use a simple authentication protocol that is bridged into existing security infrastructures, even if there is more than one authentication protocol or domain present. We position our work in the context of some of the current work going on in distributed secure file systems and present our implementation of our file system. We also present some security weaknesses that are shared with other distributed file systems that may not be apparent when designing these systems.