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User Study (user + study)
Selected AbstractsIncarceration and drug use patterns among a cohort of injection drug usersADDICTION, Issue 1 2009Kora DeBeck ABSTRACT Aims Drug law enforcement remains the dominant response to drug-related harm. However, the impact of incarceration on deterring drug use remains under-evaluated. We sought to explore the relationship between incarceration and patterns of drug use among people who inject drugs (IDU). Design Using generalized estimating equations (GEE), we examined the prevalence and correlates of injection cessation among participants in the Vancouver Injection Drug User Study followed over 9 years. In subanalyses, we used McNemar's tests and linear growth curve analyses to assess changes in drug use patterns before and after a period of incarceration among participants reporting incarceration and those not incarcerated. Findings Among 1603 IDU, 842 (53%) reported injection cessation for at least 6 months at some point during follow-up. In multivariate GEE analyses, recent incarceration was associated negatively with injection cessation [adjusted odds ratio (AOR) = 0.43, 95% confidence interval (CI) 0.37,0.50], whereas the use of methadone was associated positively with cessation (AOR = 1.38, 95% CI 1.22,1.56). In subanalyses assessing longitudinal patterns of drug use among incarcerated individuals and those not incarcerated over the study period, linear growth curve analyses indicated that there were no statistically significant differences in patterns of drug use between the two groups (all P > 0.05). Conclusions These observational data suggest that incarceration does not reduce drug use among IDU. Incarceration may inhibit access to mechanisms that promote injection cessation among IDU. In contrast, results indicate that methadone use is associated positively with injection cessation, independent of previous frequency of drug use. [source] Changes in Canadian heroin supply coinciding with the Australian heroin shortageADDICTION, Issue 5 2006Evan Wood ABSTRACT Aims Previous studies have largely attributed the Australian heroin shortage to increases in local law enforcement efforts. Because western Canada receives heroin from similar source nations, but has not measurably increased enforcement practices or funding levels, we sought to examine trends in Canadian heroin-related indices before and after the Australian heroin shortage, which began in approximately January 2001. Methods During periods before and after January 2001, we examined the number of fatal overdoses and ambulance responses to heroin-related overdoses that required the use of naloxone in British Columbia, Canada. As an overall marker of Canadian supply reduction, we also examined the quantity of heroin seized during this period. Lastly, we examined trends in daily heroin use among injection drug users enrolled in the Vancouver Injection Drug Users Study (VIDUS). Results There was a 35% reduction in overdose deaths, from an annual average of 297 deaths during the years 1998,2000 in comparison to an average of 192 deaths during 2001,03. Similarly, use of naloxone declined 45% in the period coinciding with the Australian heroin shortage. Interestingly, the weight of Canadian heroin seized declined 64% coinciding with the Australian heroin shortage, from an average of 184 kg during 1998,2000 to 67 kg on average during 2001,03. Among 1587 VIDUS participants, the period coinciding with the Australian heroin shortage was associated independently with reduced daily injection of heroin [adjusted odds ratio: 0.55 (95% CI: 0.50,0.61); P < 0.001]. Conclusions Massive decreases in three independent markers of heroin use have been observed in western Canada coinciding with the Australian heroin shortage, despite no increases in funding to Canadian enforcement efforts. Markedly reduced Canadian seizure activity also coincided with the Australian heroin shortage. These findings suggest that external global heroin supply forces deserve greater investigation and credence as a potential explanation for the Australian heroin shortage. [source] The Readability of Path-Preserving Clusterings of GraphsCOMPUTER GRAPHICS FORUM, Issue 3 2010Daniel Archambault Abstract Graph visualization systems often exploit opaque metanodes to reduce visual clutter and improve the readability of large graphs. This filtering can be done in a path-preserving way based on attribute values associated with the nodes of the graph. Despite extensive use of these representations, as far as we know, no formal experimentation exists to evaluate if they improve the readability of graphs. In this paper, we present the results of a user study that formally evaluates how such representations affect the readability of graphs. We also explore the effect of graph size and connectivity in terms of this primary research question. Overall, for our tasks, we did not find a significant difference when this clustering is used. However, if the graph is highly connected, these clusterings can improve performance. Also, if the graph is large enough and can be simplified into a few metanodes, benefits in performance on global tasks are realized. Under these same conditions, however, performance of local attribute tasks may be reduced. [source] Layered Performance Animation with Correlation MapsCOMPUTER GRAPHICS FORUM, Issue 3 2007Michael Neff Abstract Performance has a spontaneity and "aliveness" that can be difficult to capture in more methodical animation processes such as keyframing. Access to performance animation has traditionally been limited to either low degree of freedom characters or required expensive hardware. We present a performance-based animation system for humanoid characters that requires no special hardware, relying only on mouse and keyboard input. We deal with the problem of controlling such a high degree of freedom model with low degree of freedom input through the use of correlation maps which employ 2D mouse input to modify a set of expressively relevant character parameters. Control can be continuously varied by rapidly switching between these maps. We present flexible techniques for varying and combining these maps and a simple process for defining them. The tool is highly configurable, presenting suitable defaults for novices and supporting a high degree of customization and control for experts. Animation can be recorded on a single pass, or multiple layers can be used to increase detail. Results from a user study indicate that novices are able to produce reasonable animations within their first hour of using the system. We also show more complicated results for walking and a standing character that gestures and dances. [source] Face as an index: Knowing who is who using a PDAINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 1 2003Jie Yang Abstract In this article, we present a PDA-based system for extending human memory or/and information retrieval using a human face as the lookup index. The system can help a user to remember names of people whom he/she has met before and find useful information, such as names and research interests, about people whom he/she is interested in talking to. The system uses a captured face image as the lookup index to retrieve information from some available resource such as departmental directory, web sites, personal homepages, etc. We describe the development of a PDA-based face recognition system and introduce algorithms for image preprocessing to enhance the quality of the image by sharpening focus and normalizing both lighting condition and head rotation. We use a unified LDA/PCA algorithm for face recognition. We address design issues of the interface to assist in visualization and comprehension of retrieved information. We present user study and experiment results to demonstrate the feasibility of the proposed system. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13: 33,41, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10046 [source] Effects of granularity of search results on the relevance judgment behavior of engineers: Building systems for retrieval and understanding of contextJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 3 2010Panos Balatsoukas Granularity is a novel concept for presenting information in search result interfaces of hierarchical query-driven information retrieval systems in a manner that can support understanding and exploration of the context of the retrieved information (e.g., by highlighting its position in the granular hierarchy and exposing its relationship with relatives in the hierarchy). Little research, however, has been conducted on the effects of granularity of search results on the relevance judgment behavior of engineers. Engineers are highly motivated information users who are particularly interested in understanding the context of the retrieved information. Therefore, it is hypothesized that the design of systems with careful regard for granularity would improve engineers' relevance judgment behavior. To test this hypothesis, a prototype system was developed and evaluated in terms of the time needed for users to find relevant information, the accuracy of their relevance judgment, and their subjective satisfaction. To evaluate the prototype, a user study was conducted where participants were asked to complete tasks, complete a satisfaction questionnaire, and be interviewed. The findings showed that participants performed better and were more satisfied when the prototype system presented only relevant information in context. Although this study presents some novel findings about the effects of granularity and context on user relevance judgment behavior, the results should be interpreted with caution. For example, participants in this research were recruited by convenience and performed a set of simulated tasks as opposed to real ones. However, suggestions for further research are presented. [source] Prioritization strategies for video storyboard keyframesJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 5 2007Hemalata Iyer This exploratory study investigates one type of video surrogate, storyboards, in terms of their ability to summarize and communicate the themes of arts-related videos. An HTML interface containing the storyboards, videos, and instructions was developed and run in a standard browser. Three phases,consisting of storyboard evaluation, full-length video evaluation, and their comparison,were completed by each user for three different videos. The data were analyzed for issues relating to keywords, summaries, and recognition of visual style for both the storyboards and the full-length videos. The linear sequence and narrative structure of storyboards are questioned, and a three-tiered model is proposed. The first layer consists of keyframes representing the "entity" and "action" of the video's central theme, the second layer consists of "entity" and "action" keyframes with regard to background or supporting information, and the third layer is composed of keyframes representing attributes, locations, and time periods. This structure facilitates the identification of appropriate keyframes for storyboards, eliminating redundant or peripheral images, and improves the storyboard's ability to communicate the essential message of videos. The tiered model is motivated and supported by the user study as well as current research on video surrogates and classical indexing theory. [source] A semantic interface for post secondary education programsPROCEEDINGS OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE & TECHNOLOGY (ELECTRONIC), Issue 1 2008Eduardo Torres Schumann We describe a prototype for a multilingual semantic interface to the academic programs of a university. Navigating within a graph model of the academic disciplines and fields, the users are led to course and program documents. For core academic concepts, informational support is provided by language specific links to Wikipedia. The web-based prototype is currently evaluated in a user study. [source] | |||||||||||||